11,121 research outputs found
Evaluation of Casimir energies through spectral functions
This is an introductory set of lectures on elliptic differential operators
and boundary problems, and their associated spectral functions. The role of
zeta functions and traces of heat kernels in the regularization of Casimir
energies is emphasized, and the renormalization issue is discussed through
simple examples.Comment: Lectures given at the IFSAP, St. Petersburg, Russia, December 2000.
LateX, 31 page
Foreign direct investments distribution in the Russian Federation: do spatial effects matter?
In this paper we explore the hypothesis of spatial effects in the distribution of Foreign Direct Investments (FDI) across Russian regions. We make use of a model, which describes FDI inflows as resulting from an agglomeration effect (the level of FDI in a given region depends positively on the level of FDI received by the regions in its neighbourhood) and remoteness effect (the distance of each Russian regions from the most important outflows countries). Considering a panel of 68 Russian regions over the period 2000-2004 we find that the two effects play a significant role in determining FDI inflows towards Russia. The two effects are also robust to the inclusion of other widely used explanatory variables impacting the level of FDI towards countries or regions (e.g. surrounding market potential, infrastructures, investment climate)
Ultra-High Energy Cosmic Particles studies from space: super-EUSO, a possible next-generation experiment
After the Pierre Auger Observatory, it is likely that space-based experiments
might be required for next-generation studies of Ultra-High Energy Cosmic
Particles. An overview of this challenging task is presented, emphasizing the
main design issues, the criticalities and the intermediate steps required to
make this challenging task a reality
Pore formation in fluctuating membranes
We study the nucleation of a single pore in a fluctuating lipid membrane,
specifically taking into account the membrane fluctuations, as well as the
shape fluctuations of the pore. For large enough pores, the nucleation free
energy is well-described by shifts in the effective membrane surface tension
and the pore line tension. Using our framework, we derive the stability
criteria for the various pore formation regimes. In addition to the well-known
large-tension regime from the classical nucleation theory of pores, we also
find a low-tension regime in which the effective line and surface tensions can
change sign from their bare values. The latter scenario takes place at
sufficiently high temperatures, where the opening of a stable pore of finite
size is entropically favorable.Comment: 9 pages, 3 figure
Membrane morphology induced by anisotropic proteins
There are a great many proteins that localize to and collectively generate
curvature in biological fluid membranes. We study changes in the topology of
fluid membranes due to the presence of highly anisotropic, curvature-inducing
proteins. Generically, we find a surprisingly rich phase diagram with phases of
both positive and negative Gaussian curvature. As a concrete example modeled on
experiments, we find that a lamellar phase in a negative Gaussian curvature
regime exhibits a propensity to form screw dislocations of definite burgers
scalar but of both chirality. The induced curvature depends strongly on the
membrane rigidity, suggesting membrane composition can be a factor regulating
membrane sculpting to to curvature-inducing proteins.Comment: 4 pages, 4 figure
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