On the number of Mather measures of Lagrangian systems

In 1996, Ricardo Ricardo Ma\~n\'e discovered that Mather measures are in fact the minimizers of a "universal" infinite dimensional linear programming problem. This fundamental result has many applications, one of the most important is to the estimates of the generic number of Mather measures. Ma\~n\'e obtained the first estimation of that sort by using finite dimensional approximations. Recently, we were able with Gonzalo Contreras to use this method of finite dimensional approximation in order to solve a conjecture of John Mather concerning the generic number of Mather measures for families of Lagrangian systems. In the present paper we obtain finer results in that direction by applying directly some classical tools of convex analysis to the infinite dimensional problem. We use a notion of countably rectifiable sets of finite codimension in Banach (and Frechet) spaces which may deserve independent interest

Large normally hyperbolic cylinders in a priori stable Hamiltonian systems

We prove the existence of normally hyperbolic invariant cylinders in nearly integrable hamiltonian systems

Thermodynamical quantities of lattice full QCD from an efficient method

I extend to QCD an efficient method for lattice gauge theory with dynamical fermions. Once the eigenvalues of the Dirac operator and the density of states of pure gluonic configurations at a set of plaquette energies (proportional to the gauge action) are computed, thermodynamical quantities deriving from the partition function can be obtained for arbitrary flavor number, quark masses and wide range of coupling constants, without additional computational cost. Results for the chiral condensate and gauge action are presented on the $10^4$ lattice at flavor number $N_f=0$, 1, 2, 3, 4 and many quark masses and coupling constants. New results in the chiral limit for the gauge action and its correlation with the chiral condensate, which are useful for analyzing the QCD chiral phase structure, are also provided.Comment: Latex, 11 figures, version accepted for publicatio

Direct comparison of high voltage breakdown measurements in liquid argon and liquid xenon

As noble liquid time projection chambers grow in size their high voltage requirements increase, and detailed, reproducible studies of dielectric breakdown and the onset of electroluminescence are needed to inform their design. The Xenon Breakdown Apparatus (XeBrA) is a 5-liter cryogenic chamber built to characterize the DC high voltage breakdown behavior of liquid xenon and liquid argon. Electrodes with areas up to 33 cm2 were tested while varying the cathode-anode separation from 1 to 6 mm with a voltage difference up to 75 kV. A power-law relationship between breakdown field and electrode area was observed. The breakdown behavior of liquid argon and liquid xenon within the same experimental apparatus was comparable

Improvement and Taste Symmetry Breaking for Staggered Quarks

We compare several improved actions for staggered quarks. We study the effect of improvement on the taste changing interactions by calculating the splitting in the pion spectrum. We investigate the effect of the improvement on some topological properties.Comment: 3 pages, 3 figures, Lattice 2003 proceeding

On the strange quark mass with improved staggered quarks

We present results on the sum of the masses of light and strange quark using improved staggered quarks. Our calculation uses 2+1 flavours of dynamical quarks. The effects of the dynamical quarks are clearly visible.Comment: Lattice2002(spectrum) Latex 3 pages, 2 figure

Is Heavy Baryon Approach Necessary?

It is demonstrated that using an appropriately chosen renormalization condition one can respect power counting within the relativistic baryon chiral perturbation theory without appealing to the technique of the heavy baryon approach. Explicit calculations are performed for diagrams including two-loops. It is argued that the introduction of the heavy baryon chiral perturbation theory was useful but not necessary.Comment: 9 pages, 2 figures, minor changes, references adde

Axial vector form factor of nucleons in a light-cone diquark model

The nucleon axial vector form factor is investigated in a light-cone quark spectator diquark model, in which Melosh rotations are applied to both the quark and vector diquark. It is found that this model gives a very good description of available experimental data and the results have very little dependence on the parameters of the model. The relation between the nucleon axial constant and the anomalous magnetic moment of nucleons is also discussed.Comment: 8 pages, Revtex4, 1 figure, version to be published in Phys. Rev.

Why Are People Addicted to SNS? Understanding the Role of SNS Characteristics in the Formation of SNS Addiction

Research has shown that many people use social networking sites (SNS) excessively, which may lead to various negative consequences. With the aim of reducing SNS addition, this study investigates the role of SNS characteristics in the formation of SNS addiction. By applying incentive sensitization theory in the context of SNS addiction, we suggest that the compulsive motivation for using an SNS is developed by pleasurable and rewarding SNS use experiences. Social network characteristics and communication characteristics, which determine the rewards that users obtain from SNS use, moderate the relationship between habitual SNS use and SNS addiction. We develop novel behavioral measures of habitual SNS use and SNS addiction based on SNS activity logs and empirically test the research model using a large and unique dataset. Besides contributing to the theoretical development of SNS addiction, the results of this study offer practical options to help prevent SNS addiction. Moreover, the measures of SNS addiction enable the automated monitoring of user behavior on SNS, which could be useful for detecting potential SNS addicts

Tests of Profiled Steel Decks with V-stiffeners

The size and position of intermediate stiffeners in the compression flanges of thin-walled profiled steel decks exerts a strong influence on the dominant buckling mode of the flange. The ability of the deck to provide both high load carrying capacity before the onset of elastic buckling and a high ultimate load capacity may therefore be affected. A programme of tests to determine the effectiveness of intermediate stiffeners in controlling buckling modes has been undertaken. A series of specimens were loaded in pure bending resulting in various buckling waveforms prior to ultimate failure through a plastic collapse mechanism. All specimens were brake-pressed to designs that were chosen to ensure that the primary buckling took place in the elastic range and was not affected by plasticity. The experimentally determined buckling stresses were found to be comparable with studies performed using a computer analysis based on the finite strip method in which both local and distortional buckling modes were predicted. The test rig developed for the programme successfully approximated the boundary conditions implicit in the numerical model and prevented premature failure due to localised stressing at the specimen ends. A simplified design procedure for distortional buckling is proposed. The existing design procedure for local buckling in the Australian Standard AS1538-1988 is confirmed