28,593 research outputs found
Statistical Mechanics of Time Independent Non-Dissipative Nonequilibrium States
We examine the question of whether the formal expressions of equilibrium
statistical mechanics can be applied to time independent non-dissipative
systems that are not in true thermodynamic equilibrium and are nonergodic. By
assuming the phase space may be divided into time independent, locally ergodic
domains, we argue that within such domains the relative probabilities of
microstates are given by the standard Boltzmann weights. In contrast to
previous energy landscape treatments, that have been developed specifically for
the glass transition, we do not impose an a priori knowledge of the
inter-domain population distribution. Assuming that these domains are robust
with respect to small changes in thermodynamic state variables we derive a
variety of fluctuation formulae for these systems. We verify our theoretical
results using molecular dynamics simulations on a model glass forming system.
Non-equilibrium Transient Fluctuation Relations are derived for the
fluctuations resulting from a sudden finite change to the system's temperature
or pressure and these are shown to be consistent with the simulation results.
The necessary and sufficient conditions for these relations to be valid are
that the domains are internally populated by Boltzmann statistics and that the
domains are robust. The Transient Fluctuation Relations thus provide an
independent quantitative justification for the assumptions used in our
statistical mechanical treatment of these systems.Comment: 17 pages, 4 figures, minor amendment
Thermodynamics of small superconductors with fixed particle number
The Variation After Projection approach is applied for the first time to the
pairing hamiltonian to describe the thermodynamics of small systems with fixed
particle number. The minimization of the free energy is made by a direct
diagonalization of the entropy. The Variation After Projection applied at
finite temperature provides a perfect reproduction of the exact canonical
properties of odd or even systems from very low to high temperature.Comment: 4 pages, 3 figure
Landauer-B\"uttiker equation for bosonic carriers
We study the current of Bose particles between two reservoirs connected by a
one-dimensional channel. We analyze the problem from first principles by
considering a microscopic model of conductivity in the noninteracting limit.
Equations for the transient and the stationary current are derived
analytically. The asymptotic current has a form similar to the
Landauer-B\"uttiker equation for electronic current in mesoscopic devices
On a generalization of Valiron's inequality for k-hypermonogenic functions on upper half-space
We present some results on the asymptotic growth behavior of periodic k-hypermonogenic functions on upper half-space. A generalization of the classical Valiron inequality for this class of functions and some basic properties are discussed
Supply chain integration in New Zealand: benchmark comparisons with the UK automotive sector
Supply chain integration is a promising approach to cross-enterprise process improvement that is still not well understood. This research investigates the level of sophistication (maturity) of supply chain integration in New Zealand from the systems uncertainty perspective. Uncertainty levels of value streams are evaluated using the 'uncertainty circle' concept, thereby enabling benchmark comparisons of value stream performance. A sample of 21 NZ process industry value streams is assessed using a so-called Quick Scan Audit Methodology (QSAM). and the uncertainty results compared with those obtained from 21 value streams in the UK automotive sector. This benchmarking revealed that value streams in New Zealand are weakly integrated and have control mechanisms which are significantly looser than those of the UK sample, even though they face higher uncertainty on the control and demand sides. In contrast, crosscountry differences in supply and process uncertainty are marginal. While providing insights into the general health of New Zealand value streams, the authors acknowledge that the sample is not a comprehensive representation of every NZ value stream
Exotic matter on singular divisors in F-theory
We analyze exotic matter representations that arise on singular seven-brane
configurations in F-theory. We develop a general framework for analyzing such
representations, and work out explicit descriptions for models with matter in
the 2-index and 3-index symmetric representations of SU() and SU(2)
respectively, associated with double and triple point singularities in the
seven-brane locus. These matter representations are associated with Weierstrass
models whose discriminants vanish to high order thanks to nontrivial
cancellations possible only in the presence of a non-UFD algebraic structure.
This structure can be described using the normalization of the ring of
intrinsic local functions on a singular divisor. We consider the connection
between geometric constraints on singular curves and corresponding constraints
on the low-energy spectrum of 6D theories, identifying some new examples of
apparent "swampland" theories that cannot be realized in F-theory but have no
apparent low-energy inconsistency.Comment: 71 page
The Lisbon Strategy and the EU's structural productivity problem
The structural nature of the EU's productivity downturn is confirmed by the analysis in this paper, with the bulk of the deterioration emanating from an outdated and inflexible industrial structure which has been slow to adapt to the intensifying pressures of globalisation and rapid technological change. The EU's productivity problems are driven by the combined effect ofan excessive focus on low and medium-technology industries (with declining productivity growth rates and a globalisation-induced contraction in investment levels); an inability to seriously challenge the US's dominance in large areas of the ICT industry, as reflected in the relatively small size of its ICT production sector; and finally, its apparent slowness in reaping the productivity enhancing benefits of ICT in a range of ICT-using industries, although measurement issues severely complicate an assessment of the gains from ICT production and diffusion.lisbon strategy, productivity, growth, labour market, Denis, Mc Morrow, R�ger, Veugelers, structural productivity
Hypervelocity runaways from the Large Magellanic Cloud
We explore the possibility that the observed population of Galactic
hypervelocity stars (HVSs) originate as runaway stars from the Large Magellanic
Cloud (LMC). Pairing a binary evolution code with an N-body simulation of the
interaction of the LMC with the Milky Way, we predict the spatial distribution
and kinematics of an LMC runaway population. We find that runaway stars from
the LMC can contribute Galactic HVSs at a rate of . This is composed of stars at different points of
stellar evolution, ranging from the main-sequence to those at the tip of the
asymptotic giant branch. We find that the known B-type HVSs have kinematics
which are consistent with an LMC origin. There is an additional population of
hypervelocity white dwarfs whose progenitors were massive runaway stars.
Runaways which are even more massive will themselves go supernova, producing a
remnant whose velocity will be modulated by a supernova kick. This latter
scenario has some exotic consequences, such as pulsars and supernovae far from
star-forming regions, and a small rate of microlensing from compact sources
around the halo of the LMC.Comment: MNRAS, in pres
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