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Search Results: 1 - 10 of 201493 matches for " Shawn P. McKee "
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ATLAS Great Lakes Tier-2 Computing and Muon Calibration Center Commissioning
Shawn McKee
Physics , 2009,
Abstract: Large-scale computing in ATLAS is based on a grid-linked system of tiered computing centers. The ATLAS Great Lakes Tier-2 came online in September 2006 and now is commissioning with full capacity to provide significant computing power and services to the USATLAS community. Our Tier-2 Center also host the Michigan Muon Calibration Center which is responsible for daily calibrations of the ATLAS Monitored Drift Tubes for ATLAS endcap muon system. During the first LHC beam period in 2008 and following ATLAS global cosmic ray data taking period, the Calibration Center received a large data stream from the muon detector to derive the drift tube timing offsets and time-to-space functions with a turn-around time of 24 hours. We will present the Calibration Center commissioning status and our plan for the first LHC beam collisions in 2009.
Cosmic-Ray Positrons: Are There Primary Sources?
Stephane Coutu,Steven W. Barwick,James J. Beatty,Amit Bhattacharyya,Chuck R. Bower,Christopher J. Chaput,Georgia A. de Nolfo,Michael A. DuVernois,Allan Labrador,Shawn P. McKee,Dietrich Muller,James A. Musser,Scott L. Nutter,Eric Schneider,Simon P. Swordy,Gregory Tarle,Andrew D. Tomasch,Eric Torbet
Physics , 1999, DOI: 10.1016/S0927-6505(99)00011-0
Abstract: Cosmic rays at the Earth include a secondary component originating in collisions of primary particles with the diffuse interstellar gas. The secondary cosmic rays are relatively rare but carry important information on the Galactic propagation of the primary particles. The secondary component includes a small fraction of antimatter particles, positrons and antiprotons. In addition, positrons and antiprotons may also come from unusual sources and possibly provide insight into new physics. For instance, the annihilation of heavy supersymmetric dark matter particles within the Galactic halo could lead to positrons or antiprotons with distinctive energy signatures. With the High-Energy Antimatter Telescope (HEAT) balloon-borne instrument, we have measured the abundances of positrons and electrons at energies between 1 and 50 GeV. The data suggest that indeed a small additional antimatter component may be present that cannot be explained by a purely secondary production mechanism. Here we describe the signature of the effect and discuss its possible origin.
Interpreting the Atmospheric Neutrino Anomaly
R. P. Thun,S. McKee
Physics , 1998, DOI: 10.1016/S0370-2693(98)01021-1
Abstract: We suggest that the atmospheric neutrino anomaly observed in the Super-Kamiokande (and other) experiments results from the combined effects of muon-neutrino to tau-neutrino oscillations with a Delta m^2 value of approximately 0.4 eV^2 and oscillations between muon neutrinos and electron neutrinos (and vice-versa) with 0.0001 < Delta m^2 < 0.001 eV^2. With an appropriate choice of a three-neutrino mixing matrix, such a hypothesis is consistent with essentially all neutrino observations.
The application of Dempster-Shafer theory demonstrated with justification provided by legal evidence
Shawn P. Curley
Judgment and Decision Making , 2007,
Abstract: In forecasting and decision making, people can and often do represent a degree of belief in some proposition. At least two separate constructs capture such degrees of belief: likelihoods capturing evidential balance and support capturing evidential weight. This paper explores the weight or justification that evidence affords propositions, with subjects communicating using a belief function in hypothetical legal situations, where justification is a relevant goal. Subjects evaluated the impact of sets of 1--3 pieces of evidence, varying in complexity, within a hypothetical legal situation. The study demonstrates the potential usefulness of this evidential weight measure as an alternative or complement to the more-studied probability measure. Subjects' responses indicated that weight and likelihood were distinguished; that subjects' evidential weight tended toward single elements in a targeted fashion; and, that there were identifiable individual differences in reactions to conflicting evidence. Specifically, most subjects reacted to conflicting evidence that supported disjoint sets of suspects with continued support in the implicated sets, although an identifiable minority reacted by pulling back their support, expressing indecisiveness. Such individuals would likely require a greater amount of evidence than the others to counteract this tendency in support. Thus, the study identifies the value of understanding evidential weight as distinct from likelihood, informs our understanding of the psychology of individuals' judgments of evidential weight, and furthers the application and meaningfulness of belief functions as a communication language.
Charting the Course for Sustainable Small Island Tourist Development  [PDF]
Teresa L. McKee
Journal of Environmental Protection (JEP) , 2013, DOI: 10.4236/jep.2013.43030
Abstract:

This article, Charting the Course for Sustainable Small Island Tourist Development, addresses sustainability criteria for small island tourist development drawing on the history of development in the last decade in the Bocas del Toro archipelago of the Republic of Panama in the Caribbean Sea near the border of Costa Rica. Tax deferments for the development of vacation and resort properties spurred a boom in this island locale since the late 1980’s. Tourist Law 8 of the Panamanian constitution is referenced. Sustainability criteria of water supply and availability are suggested and outer island projects are discussed. Lessons are outlined and recommendations are made for permit qualifications that promote sustainable small island tourist development.

Spatio-Temporal Prediction of Root Zone Soil Moisture Using Multivariate Relevance Vector Machines  [PDF]
Bushra Zaman, Mac McKee
Open Journal of Modern Hydrology (OJMH) , 2014, DOI: 10.4236/ojmh.2014.43007
Abstract:
Root zone soil moisture at one and two meter depths are forecasted four days into the future. In this article, we propose a new multivariate output prediction approach to root zone soil moisture assessment using learning machine models. These models are known for their robustness, efficiency, and sparseness; they provide a statistically sound approach to solving the inverse problem and thus to building statistical models. The multivariate relevance vector machine (MVRVM) is used to build a model that forecasts soil moisture states based upon current soil moisture and soil temperature conditions. The methodology combines the data at different depths from 5 cm to 50 cm, the largest of which corresponds to the depth at which the soil moisture sensors are generally operational, to produce soil moisture predictions at larger depths. The MVRVM test results for soil moisture predictions at 1 m and 2 m depth on the 4th day are excellent with RMSE = 0.0131 m3/m3 for 1 m; and RMSE = 0.0015 m3/m3 for 2 m forecasted values. The statistics of predictions for 4th day (CoE = 0.87 for 1 m and CoE = 0.96 for 2 m) indicate good model generalization capability and computations show good agreement with actual measurements with R2 = 0.88 and R2 = 0.97 for 1 m and 2 m depths, respectively. The MVRVM produces good results for all four days. Bootstrapping is used to check over/under-fitting and uncertainty in model estimates.
Factors limiting productivity of the Central Arctic Caribou Herd of Alaska
Shawn P. Haskell,Warren B. Ballard
Rangifer , 2004,
Abstract: Many biotic and abiotic factors can limit productivity and growth of caribou (Rangifer tarandus) herds, but limiting factors typically vary by region. Identifying limiting factors may help to indicate which seasons are of relative importance to a caribou herd and possibly to suggest general life history strategies. Using regression techniques, we found that despite previous suggestions, net productivity of Alaska’s Central Arctic Caribou Herd (CAH) did not respond to early summer forage biomass or summer insect severity from the previous year. Abiotic factors that did have apparent effects on CAH productivity included early fall snow deposition, winter snow condition, and spring snow ablation. To achieve a suitable weight for conception, caribou of the CAH may exhibit a seasonal time-minimizing foraging strategy by moderating weight gain during the warm summer insect season and feeding more intensively during the insect-free weeks before the autumn rut. A long-term trend of the Northern Hemisphere annular mode (NAM) may be linked to anthropogenic climate change and may have negative implications for the future success of the CAH.
A Numerical Investigation of Heat Transfer Cardiac Output Measurements
P. Fotheringham,A. R. Gourlay,S. Mckee,S. Andrews
Computational and Mathematical Methods in Medicine , 2005, DOI: 10.1080/10273660500158712
Abstract: Measurement of cardiac output is often investigated using a technique based on hot-film anemometry. Here, we discuss a modification to hot-film anemometry, which involves a cylindrical heating element mounted flush on the surface of a typical Swan-Ganz catheter. In contrast to traditional thermodilution, the method discussed here has the potential to allow continuous monitoring of cardiac output.
Star Formation in Cold, Spherical, Magnetized Molecular Clouds
P. N. Safier,C. F. McKee,S. W. Stahler
Physics , 1997, DOI: 10.1086/304439
Abstract: We present an idealized, spherical model of the evolution of a magnetized molecular cloud due to ambipolar diffusion. This model allows us to follow the quasi-static evolution of the cloud's core prior to collapse and the subsequent evolution of the remaining envelope. By neglecting the thermal pressure gradients in comparison with magnetic stresses and by assuming that the ion velocity is small compared with the neutral velocity, we are able to find exact analytic solutions to the MHD equations. We show that, in the case of a centrally condensed cloud, a core of finite mass collapses into the origin leaving behind a quasi-static envelope, whereas initially homogeneous clouds never develop any structure in the absence of thermal stresses, and collapse as a whole. Prior to the collapse of the core, the cloud's evolution is characterized by two phases: a long, quasi-static phase where the relevant timescale is the ambipolar diffusion time (treated in this paper), and a short, dynamical phase where the characteristic timescale is the free-fall time. The collapse of the core is an "outside-in" collapse. The quasi-static evolution terminates when the cloud becomes magnetically supercritical; thereafter its evolution is dynamical, and a singularity develops at the origin-a protostar. After the initial formation of the protostar, the outer envelope continues to evolve quasi-statically, while the region of dynamical infall grows with time-an "inside-out" collapse. We use our solution to estimate the magnetic flux trapped in the collapsing core and the mass accretion rate onto the newly formed protostar. Our results agree, within factors of order unity, with the numerical results of Fiedler & Mouschovias (1992) for the physical quantities in the midplane of
The Structure and Evolution of Molecular Clouds: from Clumps to Cores to the IMF
Jonathan P. Williams,Leo Blitz,Christopher F. McKee
Physics , 1999,
Abstract: We review the progress that has been made in observing and analyzing molecular cloud structure in recent years. Structures are self-similar over a wide range of scales with similar power law indices independent of the star forming nature of a cloud. Comparison of structures at parsec-scale resolution in a star forming and non-star forming cloud show that the average densities in the former are higher but the structural characteristics in each cloud are much the same. In gravitationally bound regions of a cloud, however, and at higher densities and resolution, the self-similar scaling relationships break down and it is possible to observe the first steps toward star formation. High resolution observations of the dense individual star forming cores within the clumps hold the key to an empirical understanding of the origins of the stellar initial mass function.
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