5,630 research outputs found
Flat wormholes from straight cosmic strings
Special multi-cosmic string metrics are analytically extended to describe
configurations of Wheeler-Misner wormholes and ordinary cosmic strings. I
investigate in detail the case of flat, asymptotically Minkowskian,
Wheeler-Misner wormhole spacetimes generated by two cosmic strings, each with
tension .Comment: 5 pages, latex, no figure
Financial integration, international portfolio choice and the European Monetary Union
We investigate the determinants of bilateral international equity and bond portfolio reallocation across a large cross section of countries over the 1997 to 2001 period. We first argue that financial integration is not a global phenomenon, as equity and bond home biases declined significantly only among European countries, Australia, New Zealand and Singapore. Then, we show that the European Economic and Monetary Union (EMU) eased the access to the equity market and, to a larger extent, the bond market; thereby, enhancing regional financial integration in the euro area. Beside the effect of the EMU, the strongest determinants of the changes in portfolio weights are expected diversification benefits and the initial degree of underweight. JEL Classification: C13, C21, F37, G11EMU, home bias, International portfolio weights, Risk diversification
Rational Hadamard products via Quantum Diagonal Operators
We use the remark that, through Bargmann-Fock representation, diagonal
operators of the Heisenberg-Weyl algebra are scalars for the Hadamard product
to give some properties (like the stability of periodic fonctions) of the
Hadamard product by a rational fraction. In particular, we provide through this
way explicit formulas for the multiplication table of the Hadamard product in
the algebra of rational functions in \C[[z]]
Relaxed Operational Semantics of Concurrent Programming Languages
We propose a novel, operational framework to formally describe the semantics
of concurrent programs running within the context of a relaxed memory model.
Our framework features a "temporary store" where the memory operations issued
by the threads are recorded, in program order. A memory model then specifies
the conditions under which a pending operation from this sequence is allowed to
be globally performed, possibly out of order. The memory model also involves a
"write grain," accounting for architectures where a thread may read a write
that is not yet globally visible. Our formal model is supported by a software
simulator, allowing us to run litmus tests in our semantics.Comment: In Proceedings EXPRESS/SOS 2012, arXiv:1208.244
"Material" mechanics of materials
The paper outlines recent developments and prospects in the application of the continuum mechanics expressed intrinsically on the material manifold itself. This includes applications to materially inhomogeneous materials physical effects which, in this vision, manifest themselves as quasi-in homogeneities, and the notion of thermo dynamical driving force of the dissipative progress of singular point sets on the material manifold with special emphasis on fracture, shock waves and phase-transition fronts.
Non-Arrhenius conduction due to the interface-trap-induced disorder in X-doped amorphous InXZnO thin-film transistors
Thin film transistors, with channels composed of In-X-Zn oxides, IXZO, with X
dopants: Ga, Sb, Be, Mg, Ag, Ca, Al, Ni, and Cu, were fabricated and their I-V
characteristics were taken at selected temperatures in the 77K<T<300K range.
The low field mobility, mu, and the interface defect density, Nst were
extracted from the characteristics for each of the studied IXZOs. At higher T
the mobility follows the Arrhenius law with an upward distortion, increasing as
T was lowered, gradually transforming into the exp [-(T0/T)1/4] variation. We
showed that mu(T, Nst) follows mu0exp[-Eaeff(T,Nst)/kT], with T-dependent
effective activation energy Eaeff(T, Nst) accounts for the data, revealing a
linear correlation between Eaeff and Nst at higher T. Temperature variation of
Eaeff(T, Nst) was evaluated using a model assuming a random distribution of
conduction mobility edge Ec values in the oxides, stemming from spatial
fluctuations induced by disorder in the interface traps distribution. For a
Gaussian distribution of Ec, the activation energy Eaeff(T, Nst) varies
linearly with 1/T, which accounts satisfactorily for the data obtained on all
the studied IXZOs. The model also shows that Eaeff(T, Nst) is a linear function
of Nst at a fixed T, which explains the exponential decrease of mu with NST
Smoothed Affine Wigner Transform
We study a generalization of Husimi function in the context of wavelets. This
leads to a nonnegative density on phase-space for which we compute the
evolution equation corresponding to a Schr\"Aodinger equation
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