1,911 research outputs found

    Static Potential and Local Color Fields in Unquenched Three-Dimensional Lattice QCD

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    String breaking by dynamical quarks in (2+1)-d lattice QCD is demonstrated in this project, by measuring the static potential and the local color-electric field strength between a heavy quark and antiquark pair at large separations. Simulations are done for unquenched SU(2) color with two flavors of staggered quarks. An improved gluon action is used which allows simulations to be done on coarse lattices, providing an extremely efficient means to access the quark separations and propagation times at which string breaking occurs. The static quark potential is extracted using only Wilson loop operators and hence no valence quarks are present in the trial states. Results give unambiguous evidence for string breaking as the static quark potential completely saturates at twice the heavy-light meson mass at large separations. It is also shown that the local color-electric field strength between the quark pair tends toward vacuum values at large separations. Implications of these results for unquenched simulations of QCD in 4-d are drawn.Comment: 3 pages, contribution to Lattice 2002 proceedings (Confinement

    On the screening of the potential between adjoint sources in QCD3QCD_3

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    We calculate the potential between adjoint sources in SU(2)SU(2) pure gauge theory in three dimensions. We investigate whether the potential saturates at large separations due to the creation of a pair of gluelumps, colour-singlet states formed when glue binds to an adjoint source.Comment: 3 pages, uuencoded Z-compressed postscript file, contribution to Lattice '9

    Towards a Theoretical Model of Social Media Surveillance in Contemporary Society.

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    'Social media’ like Facebook or Twitter have become tremendously popular in recent years. Their popularity provides new opportunities for data collection by state and private companies, which requires a critical and theoretical focus on social media surveillance. The task of this paper is to outline a theoretical framework for defining social media surveillance in the context of contemporary society, identifying its principal characteristics, and understanding its broader societal implications. Social media surveillance is a form of surveillance in which different forms of sociality and individuals different social roles converge, so that surveillance becomes a monitoring of different activities in different social roles with the help of profiles that hold a complex networked multitude of data about humans

    Internet Surveillance after Snowden: A Critical Empirical Study of Computer Experts' Attitudes on Commercial and State Surveillance of the Internet and Social Media post-Edward Snowden

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    Acknowledgement: The research presented in this paper was conducted as part of the EU FP7 research project PACT (http://www.projectpact.eu), grant agreement number 285635

    Accurate Dynamic Response Predictions of PnPSAT I

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    Researchers at the Air Force Institute of Technology (AFIT) and the Operationally Responsive Space (ORS) Office have conducted extensive vibration testing and structural modeling on the first ORS Plug-and-Play Satellite (PnPSAT I). The intent of this research effort is to evaluate the premise that current post-integration spacecraft environmental test requirements can be reduced or modified using accurately tuned finite element (FE) models. As part of this research, modal testing was conducted on the PnPSAT I structural panels at AFIT. The modal testing was part of a much larger series of experimental trials on various configurations of PnPSAT I at the Air Force Research Laboratory (AFRL) facilities at Kirtland Air Force Base (KAFB). Multiple sets of vibration data were also collected from accelerometers on PnPSAT I from standard and modified spacecraft prelaunch sine sweep and random vibration tests. The modal data collected at AFIT is used to tune two PnPSAT I panel FE models and the random vibration data collected at KAFB is used to tune the complete satellite for one configuration. The goal is to create an accurate FE model capable of predicting the dynamic response in a frequency range of 0-300 Hz of various PnPSAT configurations. This modeling and tuning effort will be validated by comparing FE model predictions with measured vibrational response from the previously mentioned experimental trial
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