714,862 research outputs found

    Polyakov Loops and Magnetic Screening from Monopoles in SU(2) Lattice Gauge Theory

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    We present results from magnetic monopoles in SU(2)SU(2) lattice gauge theory at finite temperature. The lattices are 163×Nt16^{3}\times N_{t}, for Nt=4,6,8,12N_{t}=4,6,8,12, at β=2.5115\beta=2.5115. Quantities discussed are: the spacial string tension, Polyakov loops, and the screening of timelike and spacelike magnetic currents.Comment: 5 pages, four Postscript figures, Late

    Tribology matters

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    Tribology touches every aspect of our day to day existence and the wonder of this is that we are completely unaware how central it is to how we function. Take a snapshot of thebeginning of a normal working day for example. A typical morning start will involve brushing one's teeth with toothpaste containing mild abrasive (with a toothbrush with an optimized design for brushing efficiency), using a shampoo and conditioner which have been tested for frictional properties on a wide range of hair types, and for those who have the traditional morning fry up - lubricating the pan in advance with cooking oil to provide a boundary layer between the food and the pan and to reduce adhesion and heat transfer. It is clear that tribology plays a major role in our everyday lives. Whether starting out for work by foot, bicycle or car, friction will define whether our shoes or tyres can grip the road surface and whether the brake or clutch will do their job. If it is raining, the speed limit is modified in some countries, testifying to the influence of tribologists in decision making in the transport industries

    There's something in the way you move : horse racing and skiing are two sports where a better understanding of friction could work

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    Have you ever had the experience of gliding effortlessly across a dance floor with a partner of rugby-player proportions, yet endured a swollen ankle minutes later from the quickstep of someone half the size? Why does one twin sister seem to be "hard" on shoes while the other can make a pair last twice as long? The explanation for counterintuitive phenomena like these lies in the study of friction and wear - a field known as tribology - and an increasingly rich source of tribological data come from the science of sport

    Tribo-corrosion maps for application in bio-tribology : some new approaches

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    Advances in the study of tribo-corrosion of materials in recent years have included the development of mechanistic maps, showing the transitions between the regimes as a function of the main process parameters. In such cases, maps have been constructed in both two and three dimensions. There are now a variety of modelling algorithms which may be used to map a range of performance indicators over a multi-parameter space. The interactions of tribo-corrosion in biological environments are becoming of increasing importance

    Bio-inspired call-stack reconstruction for performance analysis

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    The correlation of performance bottlenecks and their associated source code has become a cornerstone of performance analysis. It allows understanding why the efficiency of an application falls behind the computer's peak performance and enabling optimizations on the code ultimately. To this end, performance analysis tools collect the processor call-stack and then combine this information with measurements to allow the analyst comprehend the application behavior. Some tools modify the call-stack during run-time to diminish the collection expense but at the cost of resulting in non-portable solutions. In this paper, we present a novel portable approach to associate performance issues with their source code counterpart. To address it, we capture a reduced segment of the call-stack (up to three levels) and then process the segments using an algorithm inspired by multi-sequence alignment techniques. The results of our approach are easily mapped to detailed performance views, enabling the analyst to unveil the application behavior and its corresponding region of code. To demonstrate the usefulness of our approach, we have applied the algorithm to several first-time seen in-production applications to describe them finely, and optimize them by using tiny modifications based on the analyses.We thankfully acknowledge Mathis Bode for giving us access to the Arts CF binaries, and Miguel Castrillo and Kim Serradell for their valuable insight regarding Nemo. We would like to thank Forschungszentrum Jülich for the computation time on their Blue Gene/Q system. This research has been partially funded by the CICYT under contracts No. TIN2012-34557 and TIN2015-65316-P.Peer ReviewedPostprint (author's final draft

    Inertia and delocalized twisted cohomology

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    We show that the inertia stack of a topological stack is again a topological stack. We further observe that the inertia stack of an orbispace is again an orbispace. We show how a U(1)-banded gerbe over an orbispace gives rise to a flat line bundle over its inertia stack. Via sheaf theory over topological stacks it gives rise to the twisted delocalized cohomology of the orbispace. With these results and constructions we generalize concepts, which are well-known in the smooth framework, to the topological case. In the smooth case we show, that our sheaf-theoretic definition of twisted delocalized cohomology of orbispaces coincides with former definitions using a twisted de Rham complex.Comment: 42 page

    Heating-compensated constant-temperature tunneling measurements on stacks of Bi2_2Sr2_2CaCu2_2O8+x_{8+x} intrinsic junctions

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    In highly anisotropic layered cuprates such as Bi2_2Sr2_2CaCu2_2O8+x_{8+x} tunneling measurements on a stack of intrinsic junctions in a high-bias range are often susceptible to self-heating. In this study we monitored the temperature variation of a stack ("sample stack") of intrinsic junctions by measuring the resistance change of a nearby stack ("thermometer stack") of intrinsic junctions, which was strongly thermal-coupled to the sample stack through a common Au electrode. We then adopted a proportional-integral-derivative scheme incorporated with a substrate-holder heater to compensate the temperature variation. This in-situ temperature monitoring and controlling technique allows one to get rid of spurious tunneling effects arising from the self-heating in a high bias range.Comment: 3 pages, 3 figure
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