3,457 research outputs found
Household liquidity and incremental financing decisions:theory and evidence
In this paper we develop a stochastic model for household liquidity. In the model, the optimal liquidity policy takes the form of a liquidity range. Subsequently, we use the model to calibrate the upper bound of the predicted liquidity range. Equipped with knowledge about the relevant control barriers, we run a series of empirical tests on a panel data set of Dutch households covering the period 1992-2007. The results broadly validate our theoretical predictions that households (i) exhaust most of their short-term liquid assets prior to increasing net debt, and (ii) reduce outstanding net debt at the optimally selected upper liquidity barrier. However, a small minority of households appear to act sub-optimally. Poor and vulnerable households rely too frequently on expensive forms of credit (such as overdrafts) hereby incurring substantial amounts of fees and fixed borrowing costs. Elderly households and people on social benefits tend to accumulate too much liquidity. Finally, some households take on expensive short-term credit while having substantial amounts of low-yielding liquid assets
Large scale EPR correlations and cosmic gravitational waves
We study how quantum correlations survive at large scales in spite of their
exposition to stochastic backgrounds of gravitational waves. We consider
Einstein-Podolski-Rosen (EPR) correlations built up on the polarizations of
photon pairs and evaluate how they are affected by the cosmic gravitational
wave background (CGWB). We evaluate the quantum decoherence of the EPR
correlations in terms of a reduction of the violation of the Bell inequality as
written by Clauser, Horne, Shimony and Holt (CHSH). We show that this
decoherence remains small and that EPR correlations can in principle survive up
to the largest cosmic scales.Comment: 5 figure
Do the precise measurements of the Casimir force agree with the expectations?
An upper limit on the Casimir force is found using the dielectric functions
of perfect crystalline materials which depend only on well defined material
constants. The force measured with the atomic force microscope is larger than
this limit at small separations between bodies and the discrepancy is
significant. The simplest modification of the experiment is proposed allowing
to make its results more reliable and answer the question if the discrepancy
has any relation with the existence of a new force.Comment: 9 pages, LaTeX, 2 Postscript figure
Quantum Effects in the Presence of Expanding Semi-Transparent Spherical Mirrors
We study quantum effects in the presence of a spherical semi-transparent
mirror or a system of two concentric mirrors which expand with a constant
acceleration in a flat D-dimensional spacetime. Using the Euclidean approach,
we obtain expressions for fluctuations and the renormalized value of
stress-energy tensor for a scalar non-minimally coupled massless field.
Explicit expressions are obtained for the energy fluxes at the null infinity
generated by such mirrors in the physical spacetime and their properties are
discussed.Comment: 28 pages, Paper is slightly reorganized, additional references are
adde
Classical Casimir interaction in the plane-sphere geometry
We study the Casimir interaction in the plane-sphere geometry in the
classical limit of high temperatures. In this limit, the finite conductivity of
the metallic plates needs to be taken into account. For the Drude model, the
classical Casimir interaction is nevertheless found to be independent of the
conductivity so that it can be described by a single universal function
depending only on the aspect ratio where is the interplate distance
and the sphere radius. This universal function differs from the one found
for perfect reflectors and is in principle amenable to experimental tests. The
asymptotic approach of the exact result to the Proximity Force Approximation
appears to be well fitted by polynomial expansions in .Comment: Updated version with minor modifications and addition of a referenc
Surface plasmon modes and the Casimir energy
We show the influence of surface plasmons on the Casimir effect between two
plane parallel metallic mirrors at arbitrary distances. Using the plasma model
to describe the optical response of the metal, we express the Casimir energy as
a sum of contributions associated with evanescent surface plasmon modes and
propagative cavity modes. In contrast to naive expectations, the plasmonic
modes contribution is essential at all distances in order to ensure the correct
result for the Casimir energy. One of the two plasmonic modes gives rise to a
repulsive contribution, balancing out the attractive contributions from
propagating cavity modes, while both contributions taken separately are much
larger than the actual value of the Casimir energy. This also suggests
possibilities to tailor the sign of the Casimir force via surface plasmons.Comment: 4 pages, 3 figures, revtex
Exact results for classical Casimir interactions: Dirichlet and Drude model in the sphere-sphere and sphere-plane geometry
Analytic expressions that describe Casimir interactions over the entire range
of separations have been limited to planar surfaces. Here we derive analytic
expressions for the classical or high-temperature limit of Casimir interactions
between two spheres (interior and exterior configurations), including the
sphere-plane geometry as a special case, using bispherical coordinates. We
consider both Dirichlet boundary conditions and metallic boundary conditions
described by the Drude model. At short distances, closed-form expansions are
derived from the exact result, displaying an intricate structure of deviations
from the commonly employed proximity force approximation.Comment: 5 pages, 2 figure
Casimir force under the influence of real conditions
The Casimir force is calculated analytically for configurations of two
parallel plates and a spherical lens (sphere) above a plate with account of
nonzero temperature, finite conductivity of the boundary metal and surface
roughness. The permittivity of the metal is described by the plasma model. It
is proved that in case of the plasma model the scattering formalism of quantum
field theory in Matsubara formulation underlying Lifshitz formula is well
defined and no modifications are needed concerning the zero-frequency
contribution. The temperature correction to the Casimir force is found
completely with respect to temperature and perturbatively (up to the second
order in the relative penetration depth of electromagnetic zero-point
oscillations into the metal) with respect to finite conductivity. The
asymptotics of low and high temperatures are presented and contributions of
longitudinal and perpendicular modes are determined separately. Serving as an
example, aluminium test bodies are considered showing good agreement between
the obtained analytical results and previously performed numerical
computations. The roughness correction is formally included and formulas are
given permitting to calculate the Casimir force under the influence of all
relevant factors
The role of Surface Plasmon modes in the Casimir Effect
In this paper we study the role of surface plasmon modes in the Casimir
effect. First we write the Casimir energy as a sum over the modes of a real
cavity. We may identify two sorts of modes, two evanescent surface plasmon
modes and propagative modes. As one of the surface plasmon modes becomes
propagative for some choice of parameters we adopt an adiabatic mode definition
where we follow this mode into the propagative sector and count it together
with the surface plasmon contribution, calling this contribution "plasmonic".
The remaining modes are propagative cavity modes, which we call "photonic". The
Casimir energy contains two main contributions, one coming from the plasmonic,
the other from the photonic modes. Surprisingly we find that the plasmonic
contribution to the Casimir energy becomes repulsive for intermediate and large
mirror separations. Alternatively, we discuss the common surface plasmon
defintion, which includes only evanescent waves, where this effect is not
found. We show that, in contrast to an intuitive expectation, for both
definitions the Casimir energy is the sum of two very large contributions which
nearly cancel each other. The contribution of surface plasmons to the Casimir
energy plays a fundamental role not only at short but also at large distances.Comment: 10 pages, 3 figures. TQMFA200
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