74,366 research outputs found
W/Z + b,bbar/jets at NLO using the Monte Carlo MCFM
We summarize recent progress in next-to-leading order QCD calculations made
using the Monte Carlo MCFM. In particular, we focus on the calculations of p
anti-p -> W b-bbar, Z b-bbar and highlight the significant corrections to
background estimates for Higgs searches in the channels WH and ZH at the
Tevatron. We also report on the current progress of, and strategies for, the
calculation of the process p anti-p -> W/Z + 2 jets.Comment: 4 pages, talk presented at the XXXVI Rencontres de Moriond, QCD and
High Energy Hadronic Interactions, 17-24 March 2001, Les Arcs, Savoie, Franc
Forensic flavour
Databases often receive an uninspired and uninterested response. The curriculum content of a database module generally involves the design of entity-relationship models, SQL programming, application development and advanced database applications such as data warehousing and data mining. These are often taught within the tired and relatively worn case studies of purchase order systems, retail or health care systems. However the current trend for crime scene investigation drama and the frequent stories in the news of personal tragedies involving incorrect data, missing data or data mix-up capture the attention of many. The truth is that crimes require data investigation and expert database witnesses to provide evidence and this requires database knowledge and skill. This project involved the introduction of a ‘forensic flavour’ to the teaching of databases as part of an undergraduate Computing Degree to students. The ‘forensic flavour’ involved introducing investigative and enquiry based learning techniques as well as selecting case studies based around real-life crimes and crime data. The learning objectives remained unchanged for the modules as did the curriculum content. The initial findings are that the students engaged on average 40% better and enjoyed the experience more
Teleporting bipartite entanglement using maximally entangled mixed channels
The ability to teleport entanglement through maximally entangled mixed states
as defined by concurrence and linear entropy is studied. We show how the
teleported entanglement depends on the quality of the quantum channel used, as
defined through its entanglement and mixedness, as well as the form of the
target state to be teleported. We present new results based on the fidelity of
the teleported state as well as an experimental set-up that is immediately
implementable with currently available technology.Comment: 8 pages, 7 figures, RevTeX4, Accepted for publication in the IJQI
special issue on Distributed Quantum Information Processin
Next-to-leading order predictions for WW+jet production
In this work we report on a next-to-leading order calculation of WW + jet
production at hadron colliders, with subsequent leptonic decays of the W-bosons
included. The calculation of the one-loop contributions is performed using
generalized unitarity methods in order to derive analytic expressions for the
relevant amplitudes. These amplitudes have been implemented in the parton-level
Monte Carlo generator MCFM, which we use to provide a complete next-to-leading
order calculation. Predictions for total cross-sections, as well as
differential distributions for several key observables, are computed both for
the LHC operating at 14 TeV as well as for a possible future 100 TeV
proton-proton collider.Comment: 14 pages, 7 figures; v2: several references added, 2 typos corrected.
Corresponds to published journal versio
An NPZ Model with State-Dependent Delay due to Size-Structure in Juvenile Zooplankton
The study of planktonic ecosystems is important as they make up the bottom
trophic levels of aquatic food webs. We study a closed
Nutrient-Phytoplankton-Zooplankton (NPZ) model that includes size structure in
the juvenile zooplankton. The closed nature of the system allows the
formulation of a conservation law of biomass that governs the system. The model
consists of a system of nonlinear ordinary differential equation coupled to a
partial differential equation. We are able to transform this system into a
system of delay differential equations where the delay is of threshold type and
is state-dependent. The system of delay differential equations can be further
transformed into one with fixed delay. Using the different forms of the model
we perform a qualitative analysis of the solutions, which includes studying
existence and uniqueness, positivity and boundedness, local and global
stability, and conditions for extinction. Key parameters that are explored are
the total biomass in the system and the maturity level at which the juvenile
zooplankton reach maturity. Numerical simulations are also performed to verify
our analytical results
Aerospike thrust chamber program
An existing, but damaged, 25,000-pound thrust, flightweight, oxygen/hydrogen aerospike rocket thrust chamber was disassembled and partially repaired. A description is presented of the aerospike chamber configuration and of the damage it had suffered. Techniques for aerospike thrust chamber repair were developed, and are described, covering repair procedures for lightweight tubular nozzles, titanium thrust structures, and copper channel combustors. Effort was terminated prior to completion of the repairs and conduct of a planned hot fire test program when it was found that the copper alloy walls of many of the thrust chamber's 24 combustors had been degraded in strength and ductility during the initial fabrication of the thrust chamber. The degradation is discussed and traced to a reaction between oxygen and/or oxides diffused into the copper alloy during fabrication processes and the hydrogen utilized as a brazing furnace atmosphere during the initial assembly operation on many of the combustors. The effects of the H2/O2 reaction within the copper alloy are described
Frontier exploration and the North Atlantic Igneous Province : new insights from a 2.6 km offshore volcanic sequence in the NE Faroe–Shetland Basin
Acknowledgements and Funding This work was funded by Chevron. The authors would like to acknowledge the Chevron West of Shetlands team along with the Joint Venture partners OMV, Faroe Petroleum and Indemitsu for access to data along with permission to publish this study. PGS is thanked for access to the Corona Ridge Regional Geostreamer (CRRG) data and permission to publish the seismic line. The paper was improved thanks to insightful reviews by S. M. Jones and A. Saunders, which substantially improved an earlier draft. J. Still and F. Thompson gave invaluable technical support at the University of Aberdeen, and K. Wall helped with real-time cuttings analysis.Peer reviewedPostprin
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