4,789 research outputs found
Recent progress in parton distributions and implications for LHC physics
I outline some of the most recent developments in the global fit to parton distributions
performed by the MRST collaboration
Update of MRST parton distributions.
We discuss the latest update of the MRST parton distributions in response
to the most recent data. We discuss the areas where there are hints
of difficulties in the global fit, and compare to some other updated sets of
parton distributions, particularly CTEQ6. We briefly discuss the issue of
uncertainties associated with partons
MRST global fit update.
We discuss the impact of the most recent data on the MRST global analysis -
in particular the new high-ET jet data and their implications for the gluon and
the new small x structure function data. In the light of these new data we also
consider the uncertainty in predictions for physical quantities depending on parton
distributions, concentrating on the W cross-section at hadron colliders
MRST partons and uncertainties.
We discuss uncertainties in the extraction of parton distributions from
global analyses of DIS and related data. We present conservative sets
of partons, at both NLO and NNLO, which are stable to x,Q2,W2 cuts
on the data. We give the corresponding values of S(M2
Z) and the cross
sections for W production at the Tevatron
Time to surgery for open hand injuries and the risk of surgical site infection: a prospective multicentre cohort study
Whether delaying surgery increases the risk of infection in open hand injuries is an important but unresolved topic. This prospective cohort study included 983 consecutive adults with open hand injuries treated surgically over 1 year. The risk ratio (RR) for surgical site infection was estimated by logistic regression. The median time from injury to surgery was 20 hours (range 4â90). Forty-one patients (4%) developed an infection. The risk of infection was not affected by the time to surgery (adjusted risk ratio 1.0 [95% CI: 1.0 to 1.0]) or preoperative antibiotics (adjusted risk ratio 1.8 [95% CI: 0.2 to 13]), which were provided to 95% of patients. Skin loss increased the risk of infection (adjusted risk ratio 2.6 [95% CI: 1.3 to 5.0]). Delaying surgery for open hand injuries by 4 days does not appear to increase the risk of surgical site infection
Structural parameterizations for boxicity
The boxicity of a graph is the least integer such that has an
intersection model of axis-aligned -dimensional boxes. Boxicity, the problem
of deciding whether a given graph has boxicity at most , is NP-complete
for every fixed . We show that boxicity is fixed-parameter tractable
when parameterized by the cluster vertex deletion number of the input graph.
This generalizes the result of Adiga et al., that boxicity is fixed-parameter
tractable in the vertex cover number.
Moreover, we show that boxicity admits an additive -approximation when
parameterized by the pathwidth of the input graph.
Finally, we provide evidence in favor of a conjecture of Adiga et al. that
boxicity remains NP-complete when parameterized by the treewidth.Comment: 19 page
Review and assessment of the potential of post-IR IRSL dating methods to circumvent the problem of anomalous fading in feldspar luminescence
Quartz has been the main mineral used for optically stimulated luminescence (OSL) dating of sediments over the last decade. The quartz OSL signal, however, has been shown to saturate at relatively low doses of âŒ200â400 Gy, making it difficult to be used for dating beyond about 200 thou-sand years (ka), unless the environmental dose rate is low. The infrared stimulated luminescence (IRSL) from feldspars has been shown to continue to grow to higher dose levels than quartz OSL. The application of IRSL dating of feldspars, however, has long been hampered by the anomalous fading effect. Recent progress in understanding anomalous fading of the infrared stimulated luminescence (IRSL) signals in potassium-feldspar has led to the development of post-IR IRSL (pIRIR) protocols and also a multiple elevated temperature (MET) stimulation (MET-pIRIR) protocol. These procedures have raised the prospect of isolating a non-fading IRSL component for dating Quaternary deposits containing feldspars. In this study, we review the recent progress made on (1) overcoming anomalous fading of feldspar, and (2) the development of pIRIR dating techniques for feldspar. The potential and problems associated with these methods are discussed.link_to_OA_fulltex
Review and assessment of the potential of post-IR IRSL dating methods to circumvent the problem of anomalous fading in feldspar luminescence
Quartz has been the main mineral used for optically stimulated luminescence (OSL) dating of sediments over the last decade. The quartz OSL signal, however, has been shown to saturate at relatively low doses of âŒ200â400 Gy, making it difficult to be used for dating beyond about 200 thou-sand years (ka), unless the environmental dose rate is low. The infrared stimulated luminescence (IRSL) from feldspars has been shown to continue to grow to higher dose levels than quartz OSL. The application of IRSL dating of feldspars, however, has long been hampered by the anomalous fading effect. Recent progress in understanding anomalous fading of the infrared stimulated luminescence (IRSL) signals in potassium-feldspar has led to the development of post-IR IRSL (pIRIR) protocols and also a multiple elevated temperature (MET) stimulation (MET-pIRIR) protocol. These procedures have raised the prospect of isolating a non-fading IRSL component for dating Quaternary deposits containing feldspars. In this study, we review the recent progress made on (1) overcoming anomalous fading of feldspar, and (2) the development of pIRIR dating techniques for feldspar. The potential and problems associated with these methods are discussed.link_to_OA_fulltex
Real time optimum trajectory generation for redundant/hyper-redundant serial industrial manipulators
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