526 research outputs found

    The Tinsley Diagram Revisited

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    Motivated by the recent determinations of the Hubble constant (H0)(H_0) from observations of Cepheid variables in NGC4571 and M100, we plot the Tinsley diagram with level curves of the cosmological constant (Λ)(\Lambda). Based on current estimates of the absolute ages of globular clusters we conclude that Λ>0\Lambda > 0 and, irrespective of the background spatial curvature, the universe will not recollapse. These conclusions hold for both relativistic and Newtonian models and are {\it independent} of the density parameter.Comment: 8 pages, uses aasms.sty, 1 uuencoded PostScript figure appended, (accepted to appear in Ap.J.Letters

    Force and acceleration characteristics of military foot drill: implications for injury risk in recruits

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    Background: Foot drill involving marching and drill manoeuvres is conducted regularly during basic military recruit training. Characterising the biomechanical loading of foot drill will improve our understanding of the contributory factors to lower limb overuse injuries in recruits. Aim: Quantify and compare forces, loading rates and accelerations of British Army foot drill, within and between trained and untrained personnel. Methods: 24 trained soldiers (12 men and 12 women; TRAINED) and 12 civilian men (UNTRAINED) performed marching and five drill manoeuvres on force platforms; motion capture recorded tibial position. Peak vertical impact force (PF), peak vertical loading rate (PLR), expressed as multiples of body weight (BW) and peak tibial impact acceleration (PTA) were recorded. Results: Drill manoeuvre PF, PLR and PTA were similar, but higher in TRAINED men (PF, PLR: p<0.01; PTA: p<0.05). Peak values in TRAINED men were shown for the halt (mean (SD); PF: 6.5 (1.5) BW; PLR: 983 (333) BW/s PTA; PTA: 207 (57) m/s2) and left turn (PF: 6.6 (1.7) BW; PLR: 928 (300) BW/s; 184 (62) m/s2). Marching PF, PLR, PTA were similar between groups and lower than all drill manoeuvres (PF: 1.1–1.3 BW; PLR: 42–70 BW/s; p<0.01; PTA: 23–38 m/s2; p<0.05). Conclusions: Army foot drill generates higher forces, loading rates and accelerations than activities such as running and load carriage, while marching is comparable to moderate running (10.8 km/h). The large biomechanical loading of foot drill may contribute to the high rate of overuse injuries during initial military training, and strategies to regulate/reduce this loading should be explored

    Local Evolutionary Debunking Arguments

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    Evolutionary debunking arguments in ethics aim to use facts about the evolutionary causes of ethical beliefs to undermine their justification. Global Evolutionary Debunking Arguments (GDAs) are arguments made in metaethics that aim to undermine the justification of all ethical beliefs. Local Evolutionary Debunking Arguments (LDAs) are arguments made in first‐order normative ethics that aim to undermine the justification of only some of our ethical beliefs. Guy Kahane, Regina Rini, Folke Tersman, and Katia Vavova argue for skepticism about the possibility of LDAs. They argue that LDAs cannot be successful because they over‐extend in a way that makes them self‐undermining and yield a form of moral skepticism. In this paper I argue that this skepticism about the possibility of LDAs is misplaced

    Open Educational Resources in Kentucky

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    Open educational resources (OER) play an increasingly important role in the education landscape, with increased awareness and use year over year (Coffey). Often, academic libraries play a supporting role for instructors as they locate, adopt, and create OER for their courses. In this article, we will provide an introduction to OER, outline some current trends in open education, and describe a few of the OER initiatives currently underway in Kentucky’s college and university libraries

    Monitoring the US ATLAS Network Infrastructure with perfSONAR-PS

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    Global scientific collaborations, such as ATLAS, continue to push the network requirements envelope. Data movement in this collaboration is routinely including the regular exchange of petabytes of datasets between the collection and analysis facilities in the coming years. These requirements place a high emphasis on networks functioning at peak efficiency and availability; the lack thereof could mean critical delays in the overall scientific progress of distributed data-intensive experiments like ATLAS. Network operations staff routinely must deal with problems deep in the infrastructure; this may be as benign as replacing a failing piece of equipment, or as complex as dealing with a multi-domain path that is experiencing data loss. In either case, it is crucial that effective monitoring and performance analysis tools are available to ease the burden of management. We will report on our experiences deploying and using the perfSONAR-PS Performance Toolkit at ATLAS sites in the United States. This software creates a dedicated monitoring server, capable of collecting and performing a wide range of passive and active network measurements. Each independent instance is managed locally, but able to federate on a global scale; enabling a full view of the network infrastructure that spans domain boundaries. This information, available through web service interfaces, can easily be retrieved to create customized applications. The US ATLAS collaboration has developed a centralized ñ€ơÄÃÂșdashboardñ€ơÄÃÂč offering network administrators, users, and decision makers the ability to see the performance of the network at a glance. The dashboard framework includes the ability to notify users (alarm) when problems are found, thus allowing rapid response to potential problems and making perfSONAR-PS crucial to the operation of our distributed computing infrastructure.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98635/1/1742-6596_396_4_042038.pd
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