4,059 research outputs found
Quantifying Timing Leaks and Cost Optimisation
We develop a new notion of security against timing attacks where the attacker
is able to simultaneously observe the execution time of a program and the
probability of the values of low variables. We then show how to measure the
security of a program with respect to this notion via a computable estimate of
the timing leakage and use this estimate for cost optimisation.Comment: 16 pages, 2 figures, 4 tables. A shorter version is included in the
proceedings of ICICS'08 - 10th International Conference on Information and
Communications Security, 20-22 October, 2008 Birmingham, U
An Algorithmic Approach to Quantum Field Theory
The lattice formulation provides a way to regularize, define and compute the
Path Integral in a Quantum Field Theory. In this paper we review the
theoretical foundations and the most basic algorithms required to implement a
typical lattice computation, including the Metropolis, the Gibbs sampling, the
Minimal Residual, and the Stabilized Biconjugate inverters. The main emphasis
is on gauge theories with fermions such as QCD. We also provide examples of
typical results from lattice QCD computations for quantities of
phenomenological interest.Comment: 44 pages, to be published in IJMP
Properties of charmonium in lattice QCD with 2+1 flavors of improved staggered sea quarks
We use the dynamical gluon configurations provided by the MILC collaboration
in a study of the charmonium spectrum and psi leptonic width. We examine sea
quark effects on mass splitting and on the leptonic decay matrix element for
light masses as low as m_s/5, while keeping the strange quark mass fixed and
the lattice spacing nearly constant.Comment: Lattice2003(heavy
Light hadrons with improved staggered quarks: approaching the continuum limit
We have extended our program of QCD simulations with an improved
Kogut-Susskind quark action to a smaller lattice spacing, approximately 0.09
fm. Also, the simulations with a approximately 0.12 fm have been extended to
smaller quark masses. In this paper we describe the new simulations and
computations of the static quark potential and light hadron spectrum. These
results give information about the remaining dependences on the lattice
spacing. We examine the dependence of computed quantities on the spatial size
of the lattice, on the numerical precision in the computations, and on the step
size used in the numerical integrations. We examine the effects of
autocorrelations in "simulation time" on the potential and spectrum. We see
effects of decays, or coupling to two-meson states, in the 0++, 1+, and 0-
meson propagators, and we make a preliminary mass computation for a radially
excited 0- meson.Comment: 43 pages, 16 figure
Lifetimes of b-flavoured hadrons
I discuss the heavy quark expansion for the inclusive widths of heavy-light
hadrons, which predicts quite well the experimental ratios of B_q meson
lifetimes. As for , current determinations of
contribution to do not allow to explain the small measured
value of . As a final topic, I discuss the
implications of the measurement of the B_c lifetime.Comment: LaTex, 4 pages, 1 figure. Talk given at the "U.K. Phenomenology
Workshop on Heavy Flavours and CP violation" Durham, 17-22 Sep. 2000 (Mixing
and Lifetimes Working Group
Transglutaminase-catalyzed preparation of chitosan-ovalbumin films
Microbial transglutaminase was employed as catalyst for preparing chitosan–ovalbumin films. The films showed low solubility at a wide range
of pH and underwent to a good enzymatic hydrolysis with trypsin. The degree of swelling was reduced and the mechanical resistance of the
chitosan–ovalbumin films increased from 24 to 35MPa after enzymatic treatment with transglutaminase. The barrier efficiency toward water
vapour was slightly improved for the films prepared by transglutaminase-mediated cross-linking
Putrescine-polysaccharide conjugate as transglutaminase substrates and their possible use in producing crosslinked films
Putrescine (1,4-diaminobutane) was covalently linked to alginate and low-methoxyl pectin to synthesize new aminated polysaccharides. Both putrescine-pectin and -alginate conjugates, although the latter at higher concentrations, were found to be able to act as effective acyl acceptor transglutaminase substrates in vitro using both dimethylated casein and soy flour proteins as acyl donors. Monodansylcadaverine, a well known acyl acceptor transglutaminase substrate, dose-dependently counteracted the covalent binding of the aminated polysaccharides to the proteins. Putrescine-pectin conjugate was also tested to prepare, in combination with soy flour proteins, edible films in the presence of purified microbial transglutaminase. Characterization of the enzymatically crosslinked films showed a significant decreased water vapor permeability, with respect to the ones obtained with non-aminated pectin in the presence of transglutaminase, as well as improved mechanical properties, such as high extensibility. Possible biotechnological applications of hydrocolloid films containing putrescine-polysaccharide derivatives enzymatically crosslinked to proteins were suggested
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