16,266 research outputs found
Planar Two-Loop Five-Parton Amplitudes from Numerical Unitarity
We compute a complete set of independent leading-color two-loop five-parton
amplitudes in QCD. These constitute a fundamental ingredient for the
next-to-next-to-leading order QCD corrections to three-jet production at hadron
colliders. We show how to consistently consider helicity amplitudes with
external fermions in dimensional regularization, allowing the application of a
numerical variant of the unitarity approach. Amplitudes are computed by
exploiting a decomposition of the integrand into master and surface terms that
is independent of the parton type. Master integral coefficients are numerically
computed in either finite-field or floating-point arithmetic and combined with
known analytic master integrals. We recompute two-loop leading-color
four-parton amplitudes as a check of our implementation. Results are presented
for all independent four- and five-parton processes including contributions
with massless closed fermion loops.Comment: v3: corrected wrong signs for five-gluon amplitudes with
vanishing tree
No Time Asymmetry from Quantum Mechanics
With CPT-invariant initial conditions that commute with CPT-invariant final
conditions, the respective probabilities (when defined) of a set of histories
and its CPT reverse are equal, giving a CPT-symmetric universe. This leads me
to question whether the asymmetry of the Gell-Mann--Hartle decoherence
functional for ordinary quantum mechanics should be interpreted as an asymmetry
of {\it time} .Comment: 14 pages, Alberta-Thy-11-9
STUDY OF CAMELLIA SINENSIS AND BOSWELLIA SERRATA IN RESPECT TO ANTIANGIOGENIC EFFECT
Objective: The process of angiogenesis is finely balanced by Proangiogenic factors and antiangiogenic factors. Any imbalance between these factors may result in a group of diseases with varied morphologic and pathologic changes, called angiogenesis dependent diseases. One has to arrest the growth of unwanted blood vessels like in metastasis of tumour, arthritis, retinopathies, etc. As the angiogenesis is simultaneously controlled by several factors, one needs to target the whole process through a holistic approach i.e. targeting more than one mechanism at a time. Objective of our study was to evaluate antiangiogenic potentials of Camellia sinensis and Boswellia serrata in whole animal models along with their safety individually as well as in combination.
Methods: These extracts were evaluated for their antiangiogenic effect using three models – Chicken Chorioallentoic membrane assay, Rat Subcutaneous air sac and Mesenteric window angiogenesis.
Results: The results of toxicity study showed that aqueous extracts of Camellia sinensis and Boswellia serrata are safe on oral administration in acute as well as repeated dose toxicity studies. It also showed antiangiogenic effects of individual extracts as well as their combinations. The study suggests that there may be synergistic effect in these extracts particularly in mesenteric window model.
Conclusion: From the study it can be concluded that these extracts can be clinically evaluated on angiogenesis dependent diseases
Towards operational measures of computer security
Ideally, a measure of the security of a system should capture quantitatively the intuitive notion of ‘the ability of the system to resist attack’. That is, it should be operational, reflecting the degree to which the system can be expected to remain free of security breaches under particular conditions of operation (including attack). Instead, current security levels at best merely reflect the extensiveness of safeguards introduced during the design and development of a system. Whilst we might expect a system developed to a higher level than another to exhibit ‘more secure behaviour’ in operation, this cannot be guaranteed; more particularly, we cannot infer what the actual security behaviour will be from knowledge of such a level. In the paper we discuss similarities between reliability and security with the intention of working towards measures of ‘operational security’ similar to those that we have for reliability of systems. Very informally, these measures could involve expressions such as the rate of occurrence of security breaches (cf rate of occurrence of failures in reliability), or the probability that a specified ‘mission’ can be accomplished without a security breach (cf reliability function). This new approach is based on the analogy between system failure and security breach. A number of other analogies to support this view are introduced. We examine this duality critically, and have identified a number of important open questions that need to be answered before this quantitative approach can be taken further. The work described here is therefore somewhat tentative, and one of our major intentions is to invite discussion about the plausibility and feasibility of this new approach
Spinning Down a Black Hole With Scalar Fields
We study the evolution of a Kerr black hole emitting scalar radiation via the
Hawking process. We show that the rate at which mass and angular momentum are
lost by the black hole leads to a final evolutionary state with nonzero angular
momentum, namely .Comment: 4 pages (including 3 postscript figures), Revtex, uses epsf.tex,
twocolumn.sty and header.sty (included). Submitted to Physical Review Letter
Imide and isatin derivatives as β-lactam mimics of β-lactam antibiotics
Activated γ-lactams, which are derivatives of succinimide, phthalimide and isatin with suitable
elements of molecular recognition, have been synthesised as mimics of the ß-lactam antibiotics
and their chemical and biological reactivity determined
Observation of infinite-range intensity correlations above, at and below the 3D Anderson localization transition
We investigate long-range intensity correlations on both sides of the
Anderson transition of classical waves in a three-dimensional (3D) disordered
material. Our ultrasonic experiments are designed to unambiguously detect a
recently predicted infinite-range C0 contribution, due to local density of
states fluctuations near the source. We find that these C0 correlations, in
addition to C2 and C3 contributions, are significantly enhanced near mobility
edges. Separate measurements of the inverse participation ratio reveal a link
between C0 and the anomalous dimension \Delta_2, implying that C0 may also be
used to explore the critical regime of the Anderson transition.Comment: 13 pages, 11 figures (main text plus supplemental information).
Updated version includes an improved introductory paragraph, minor text
revisions, a revised title and additional supplemental information on the
experimental detail
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