76,952 research outputs found

    Mass participation user trials

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    This thesis investigates how researchers can take advantage of the rapid adoption of mobile technology that has brought with it transformations in social and cultural practice; the expectations of what computers are, what they can do, and the role of digital objects in everyday life. In particular this thesis presents and discuses the use of new App Store style software distribution methods to reduce the cost, in terms of researcher time and hardware, of recruiting a large group of participants for a trial ‘in the wild’ while increasing the potential diversity of users is becoming an attractive option for researchers pursuing the ubicomp vision. It examines the procedures for running large scale trials with the deployment of three applications released to a combined user base of over 135,000 in such a way as to keep the qualitative detail necessary to inform design while gain- ing the diversity of users for claims of generalisability. More generally, it discusses the results that can be expected from this ‘mass participation’ approach, and the ethical responsibilities they place upon researchers. The contributions of this thesis for mobile HCI show that in large-scale trials, relatively rich qualitative data can be collected along with substantial quantitative data, and that a hybrid trial methodology combining a large- scale deployment with a local trial can be a powerful tool in addressing shortcomings of trials that are either solely local or solely global. This thesis also contributes guidelines for researchers running large-scale user trials that give consideration to the established research norms and practices, in an attempt to strike a new balance between invasiveness and utility

    User Participation in Value Creation

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    This article examines HM Treasury’s proposal to account for the active participation of users in value creation in certain digital platforms. The first key question is whether there is any reason to believe, as HM Treasury suggests, that users only meaningfully or actively contribute to value creation in the context of certain digital platforms. The article accordingly explores the factors HM Treasury sets out for the attribution of income to active user participation, including features such as network effects, multisided business models, and a lack of physical presence in the jurisdiction of the user. It concludes that if a user participation concept were adopted into international tax norms, it is unlikely to be limited to digital businesses or to the business models particularly highlighted in the proposal issued by HM Treasury. The analysis proceeds by considering the factors set out by HM Treasury for the attribution of income to active user participation in the context of pharmaceuticals and biologics, the financial sector, and the “internet of things”. For example, the article concludes that under HM Treasury’s user participation theory, returns from certain London-based financial intermediation businesses would need to be reallocated to other jurisdictions. Moreover, as the internet of things develops, one would expect the range of business affected by the active user participation concept to constantly expand

    Mobility is the Message: Experiments with Mobile Media Sharing

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    This thesis explores new mobile media sharing applications by building, deploying, and studying their use. While we share media in many different ways both on the web and on mobile phones, there are few ways of sharing media with people physically near us. Studied were three designed and built systems: Push!Music, Columbus, and Portrait Catalog, as well as a fourth commercially available system – Foursquare. This thesis offers four contributions: First, it explores the design space of co-present media sharing of four test systems. Second, through user studies of these systems it reports on how these come to be used. Third, it explores new ways of conducting trials as the technical mobile landscape has changed. Last, we look at how the technical solutions demonstrate different lines of thinking from how similar solutions might look today. Through a Human-Computer Interaction methodology of design, build, and study, we look at systems through the eyes of embodied interaction and examine how the systems come to be in use. Using Goffman’s understanding of social order, we see how these mobile media sharing systems allow people to actively present themselves through these media. In turn, using McLuhan’s way of understanding media, we reflect on how these new systems enable a new type of medium distinct from the web centric media, and how this relates directly to mobility. While media sharing is something that takes place everywhere in western society, it is still tied to the way media is shared through computers. Although often mobile, they do not consider the mobile settings. The systems in this thesis treat mobility as an opportunity for design. It is still left to see how this mobile media sharing will come to present itself in people’s everyday life, and when it does, how we will come to understand it and how it will transform society as a medium distinct from those before. This thesis gives a glimpse at what this future will look like

    Estimating the impact of time-based road user charges on risk taking by drivers.

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    This study, conducted for ethical reasons on a driving simulator, has indicated that drivers take more risks when they are being charged for their use of roadspace on the basis of time, than they do when they are not subject to such charges. This effect is highly significant for some measures of risk taking (e.g. red light violation and illegal overtaking) but less so for others. The effect is apparent even at very low charge levels and is observed irrespective of whether the charge is based on total travel time or time spent below specified speeds (‘congestion charges’). There are however some differences in the types of risky behaviour engendered by these two charging regimes. These results have obvious and serious implications for the implementation of time-based road user charges

    Safety of the Deferral of Coronary Revascularization on the Basis of Instantaneous Wave-Free Ratio and Fractional Flow Reserve Measurements in Stable Coronary Artery Disease and Acute Coronary Syndromes.

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    OBJECTIVES: The aim of this study was to investigate the clinical outcomes of patients deferred from coronary revascularization on the basis of instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) measurements in stable angina pectoris (SAP) and acute coronary syndromes (ACS). BACKGROUND: Assessment of coronary stenosis severity with pressure guidewires is recommended to determine the need for myocardial revascularization. METHODS: The safety of deferral of coronary revascularization in the pooled per-protocol population (n = 4,486) of the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) and iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) randomized clinical trials was investigated. Patients were stratified according to revascularization decision making on the basis of iFR or FFR and to clinical presentation (SAP or ACS). The primary endpoint was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year. RESULTS: Coronary revascularization was deferred in 2,130 patients. Deferral was performed in 1,117 patients (50%) in the iFR group and 1,013 patients (45%) in the FFR group (p < 0.01). At 1 year, the MACE rate in the deferred population was similar between the iFR and FFR groups (4.12% vs. 4.05%; fully adjusted hazard ratio: 1.13; 95% confidence interval: 0.72 to 1.79; p = 0.60). A clinical presentation with ACS was associated with a higher MACE rate compared with SAP in deferred patients (5.91% vs. 3.64% in ACS and SAP, respectively; fully adjusted hazard ratio: 0.61 in favor of SAP; 95% confidence interval: 0.38 to 0.99; p = 0.04). CONCLUSIONS: Overall, deferral of revascularization is equally safe with both iFR and FFR, with a low MACE rate of about 4%. Lesions were more frequently deferred when iFR was used to assess physiological significance. In deferred patients presenting with ACS, the event rate was significantly increased compared with SAP at 1 year.info:eu-repo/semantics/publishedVersio

    How should we assess the mechanical properties of lower-limb prosthesis technology used in elite sport?: An initial investigation

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    Despite recent controversy, it is not yet formally recognised how lower-limb prosthesis should be assessed for their performance. To assist in this process, experiments are undertaken to investigate the linearity, stiffness and assessment of feet based energy return prosthesis technology typically used for elite level high speed running. Through initial investigations, it is concluded that static load testing would not be recommended to specify or regulate energy return prostheses for athletes with a lower-limb amputation. Furthermore, an assessment of energy return technology when loaded under dynamic conditions demonstrates changes in mechanical stiffness due to bending and effective blade length variation during motion. Such radical changes of boundary conditions due to loading suggest that any assessment of lower-limb prosthesis technology in the future should use methods that do not assume linear mechanical stiffness. The research into such effects warrants further investigation in the future

    QuPARA: Query-Driven Large-Scale Portfolio Aggregate Risk Analysis on MapReduce

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    Stochastic simulation techniques are used for portfolio risk analysis. Risk portfolios may consist of thousands of reinsurance contracts covering millions of insured locations. To quantify risk each portfolio must be evaluated in up to a million simulation trials, each capturing a different possible sequence of catastrophic events over the course of a contractual year. In this paper, we explore the design of a flexible framework for portfolio risk analysis that facilitates answering a rich variety of catastrophic risk queries. Rather than aggregating simulation data in order to produce a small set of high-level risk metrics efficiently (as is often done in production risk management systems), the focus here is on allowing the user to pose queries on unaggregated or partially aggregated data. The goal is to provide a flexible framework that can be used by analysts to answer a wide variety of unanticipated but natural ad hoc queries. Such detailed queries can help actuaries or underwriters to better understand the multiple dimensions (e.g., spatial correlation, seasonality, peril features, construction features, and financial terms) that can impact portfolio risk. We implemented a prototype system, called QuPARA (Query-Driven Large-Scale Portfolio Aggregate Risk Analysis), using Hadoop, which is Apache's implementation of the MapReduce paradigm. This allows the user to take advantage of large parallel compute servers in order to answer ad hoc risk analysis queries efficiently even on very large data sets typically encountered in practice. We describe the design and implementation of QuPARA and present experimental results that demonstrate its feasibility. A full portfolio risk analysis run consisting of a 1,000,000 trial simulation, with 1,000 events per trial, and 3,200 risk transfer contracts can be completed on a 16-node Hadoop cluster in just over 20 minutes.Comment: 9 pages, IEEE International Conference on Big Data (BigData), Santa Clara, USA, 201

    The Influence of CrossFit Training on Running Mechanics

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    Introduction 40 million Americans run regularly.1 Contrary to many runner’s beliefs, increased strength may be beneficial while not adding body mass. An increase in strength in specific muscles may improve running gait and performance. 9,6 Strength training may also play an important role in preventing common overuse injuries in running 11,12 Depending on the style of strength training, it may also have an enhanced benefit on running economy.4,16 Participation in CrossFit is also widely popular, with an increase in participation of 923% in the past ten years.2 CrossFit is a type of strength training in which most movements performed utilize the hip to generate a majority of the power for successful completion.8 Muscles of the hip and knee are imperative during many CrossFit movements, but also during running. Purpose The purpose of this study is to investigate the influence that CrossFit training has on running mechanics. Methods 18 recreational runners between the ages of 18-65 were recruited in each of two groups: 9 runners that also participate in CrossFit 3 times per week, and 9 runners that do not do any strength training. Inclusion criteria included running at least 10 miles a week. Participants gave written consent and completed a demographic questionnaire and Physical Activity Readiness Questionnaire. Following consent, InBody (570, InBody USA, Cerritos, CA) bioelectric impedance body composition was collected. Participants then completed a 5-minute treadmill warm-up. Retro-reflective markers were placed bilaterally on the shoulders and hips and unilaterally on the leg and foot. Data collection was completed over ground along a 10-meter runway with three embedded force platforms (1000 Hz, AMTI Optima, Watertown, MA). Preferred running velocity was then determined. Participants performed two separate conditions; preferred running velocity (C1) and a set velocity of 3.5 m/s (C2). Trials were collected via three-dimensional motion capture system (200 Hz, Vicon, MX and Vantage, Oxfordshire, UK) and photoelectric timing gates. Eight successful trials were collected for each condition. Participants then performed strength testing of the hip and knee to determine peak torque using the isokinetic dynamometer (Biodex System 3, Biodex Medical Systems Shirley, NY) each consisting of one set of five reps at 120 °/s . Data Analysis Following collection, trials were individually processed using Vicon Nexus software (version 2.2.3, Oxfrodshire, UK). Trials were then exported to Visual 3D (version 5, Germantown, MD) and further processed. Statistics Kinematic and kinetic variables were analyzed with a 2x2 repeated measures ANOVA. Strength variables were analyzed with independent t-tests. Alpha level was set to 0.05. Results There was a significant difference between the CF group and the RO group in all of the strength measures, with the CF group having greater strength. For hip ROM, there were no significant differences between the groups, but there was a significant difference between the conditions. Discussion Although there were few differences between the two groups, the main finding of this study is that the CrossFit group was significantly stronger than the run-only group. This is of importance because it demonstrates that even though the CrossFit group was stronger, the running mechanics of the two groups were similar

    Determination of step rate thresholds corresponding to physical activity intensity classifications in adults

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    Current recommendations call for adults to be physically active at moderate and/or vigorous intensities. Given the popularity of walking and running, the use of step rates may provide a practical and inexpensive means to evaluate ambulatory intensity. Thus, the purpose of this study was to identify step rate thresholds that correspond to various intensity classifications. Methods: Oxygen consumption was measured at rest and during 10 minute treadmill walking and running trials at 6 standardized speeds (54, 80, 107, 134, 161, and 188 m∙min-1) in 9 men and 10 women (28.8 ± 6.8 yrs). Two observers counted the participants’ steps at each treadmill speed. Linear and nonlinear regression analyses were used to develop prediction equations to ascertain step rate thresholds at various intensities. Results: Nonlinear regression analysis of the metabolic cost versus step rates across all treadmill speeds yielded the highest R2 values for men (R2 = .91) and women (R2 = .79). For men, the nonlinear analysis yielded 94 and 125 step∙min-1 for moderate and vigorous intensities, respectively. For women, 99 and 135 step∙min-1 corresponded with moderate and vigorous intensities, respectively. Conclusions: Promoting a step rate of 100 step∙min-1 may serve as a practical public health recommendation to exercise at moderate intensity
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