4,158 research outputs found
Chartier Daniel, 2010, La spectaculaire déroute de l’Islande. Montréal, Presses de l’Université du Québec, 234 p., chron., bibliogr. (Maxime Robert)
Effects of Increased Step Width on Knee Joint Biomechanics in Healthy and Knee Osteoarthritis Older Adults During Stair Descent
Stair negotiation is one of the most challenging tasks for older adults especially for those suffering from knee osteoarthritis (OA). To date, no studies have investigated the effects of increased step width (SW) on knee joint biomechanics. The purpose of Study One was to investigate the effects of increased SW on peak internal knee abduction moment and other lower extremity variables during stair descent in healthy older adults. The purpose of Study Two was to investigate the effects of increased SW on peak internal knee abduction moment, knee pain and other lower extremity variables during stair descent in medial compartment knee OA adults. A motion analysis system and an instrumented staircase were used to collect lower extremity joint biomechanics in both studies. Participants performed five stair descent trials at their self-selected speed at preferred, wide and wider SW.
Study One: Twenty healthy adults (54.9±9.1 years) were recruited for this study. The preferred normalized SW in healthy adults during stair descent was 20% of leg length. The results indicated that increased SW during stair descent reduced 1st and 2nd peak internal knee abduction moments in healthy adults. These abduction moment reductions may be caused by a less adducted knee with increased SW. These results may have implications in reducing medial compartment knee loads in stair descent in healthy adults to potentially help prevent medial compartment knee OA onset.
Study Two: Thirteen medial compartment knee OA patients (62.5±9.0 years) were recruited for this study. Increased SW did not change subjective knee pain in knee OA patients. Preferred SW in knee OA adults during stair descent was 20% of leg length. The increased SW during stair descent reduced 2nd peak knee adduction angle but did not reduce peak internal knee abduction moments in knee OA patients. It appears that earlier timing of 2nd peak adduction angle with increased SW may be related to the unchanged 2nd peak abduction moment. Further studies investigating simulated muscle forces and compartmentalized joint forces in medial compartment knee OA patients during stair negotiation are warranted to obtain a more accurate depiction of medial knee joint loads
La neutralité de l'internet, la gestion du trafic et les services gérés:à la recherche de définitions
Temperature can enhance coherent oscillations at a Landau-Zener transition
We consider sweeping a system through a Landau-Zener avoided-crossing, when
that system is also coupled to an environment or noise. Unsurprisingly, we find
that decoherence suppresses the coherent oscillations of quantum superpositions
of system states, as superpositions decohere into mixed states. However, we
also find an effect we call "Lamb-assisted coherent oscillations", in which a
Lamb shift exponentially enhances the coherent oscillation amplitude. This
dominates for high-frequency environments such as super-Ohmic environments,
where the coherent oscillations can grow exponentially as either the
environment coupling or temperature are increased. The effect could be used as
an experimental probe for high-frequency environments in such systems as
molecular magnets, solid-state qubits, spin-polarized gases (neutrons or He3)
or Bose-condensates.Comment: 4 Pages & 4 Figs - New version: introduction extended & citations
adde
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Robust model-based analysis of single-particle tracking experiments with Spot-On.
Single-particle tracking (SPT) has become an important method to bridge biochemistry and cell biology since it allows direct observation of protein binding and diffusion dynamics in live cells. However, accurately inferring information from SPT studies is challenging due to biases in both data analysis and experimental design. To address analysis bias, we introduce 'Spot-On', an intuitive web-interface. Spot-On implements a kinetic modeling framework that accounts for known biases, including molecules moving out-of-focus, and robustly infers diffusion constants and subpopulations from pooled single-molecule trajectories. To minimize inherent experimental biases, we implement and validate stroboscopic photo-activation SPT (spaSPT), which minimizes motion-blur bias and tracking errors. We validate Spot-On using experimentally realistic simulations and show that Spot-On outperforms other methods. We then apply Spot-On to spaSPT data from live mammalian cells spanning a wide range of nuclear dynamics and demonstrate that Spot-On consistently and robustly infers subpopulation fractions and diffusion constants
Descartes: Generating Short Descriptions of Wikipedia Articles
Wikipedia is one of the richest knowledge sources on the Web today. In order
to facilitate navigating, searching, and maintaining its content, Wikipedia's
guidelines state that all articles should be annotated with a so-called short
description indicating the article's topic (e.g., the short description of beer
is "Alcoholic drink made from fermented cereal grains"). Nonetheless, a large
fraction of articles (ranging from 10.2% in Dutch to 99.7% in Kazakh) have no
short description yet, with detrimental effects for millions of Wikipedia
users. Motivated by this problem, we introduce the novel task of automatically
generating short descriptions for Wikipedia articles and propose Descartes, a
multilingual model for tackling it. Descartes integrates three sources of
information to generate an article description in a target language: the text
of the article in all its language versions, the already-existing descriptions
(if any) of the article in other languages, and semantic type information
obtained from a knowledge graph. We evaluate a Descartes model trained for
handling 25 languages simultaneously, showing that it beats baselines
(including a strong translation-based baseline) and performs on par with
monolingual models tailored for specific languages. A human evaluation on three
languages further shows that the quality of Descartes's descriptions is largely
indistinguishable from that of human-written descriptions; e.g., 91.3% of our
English descriptions (vs. 92.1% of human-written descriptions) pass the bar for
inclusion in Wikipedia, suggesting that Descartes is ready for production, with
the potential to support human editors in filling a major gap in today's
Wikipedia across languages
It’s All Rocket Science: On the Equivalence of Development Timelines for Aerospace and Nuclear Technologies
Early in the lifecycle of a system development, systems engineers must execute
trade studies to allocate resources between different research and development efforts that are
developing technologies to be deployed into the system, and they must prepare risk
management plans for the selected technologies. We have been developing a statistical model
for schedule and cost uncertainty based on a small number of inputs that are quite objective
and are already integrated with technology readiness assessment. An algorithm that
transforms Technical Maturity (TM) scores from Department of Energy projects into a
Technology Readiness Level (TRL) score was created, allowing us to add data from a US
Department of Energy to an existing set of data from NASA. We statistically tested whether
the two samples (i.e. the DoE and NASA datasets) were randomly drawn from the same
population and concluded that the transition times for developing aerospace and nuclear
technologies are very similar
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