55,344 research outputs found
A Comment on "Memory Effects in an Interacting Magnetic Nanoparticle System"
Recently, Sun et al reported that striking memory effects had been clearly
observed in their new experiments on an interacting nanoparticle system [1].
They claimed that the phenomena evidenced the existence of a spin-glass-like
phase and supported the hierarchical model. No doubt that a particle system may
display spin-glass-like behaviors [2]. However, in our opinion, the experiments
in Ref. [1] cannot evidence the existence of spin-glass-like phase at all. We
will demonstrate below that all the phenomena in Ref. [1] can be observed in a
non-interacting particle system with a size distribution. Numerical simulations
of our experiments also display the same features.Comment: A comment on "Phys. Rev. Lett. 91, 167206
Optimal Geo-Indistinguishable Mechanisms for Location Privacy
We consider the geo-indistinguishability approach to location privacy, and
the trade-off with respect to utility. We show that, given a desired degree of
geo-indistinguishability, it is possible to construct a mechanism that
minimizes the service quality loss, using linear programming techniques. In
addition we show that, under certain conditions, such mechanism also provides
optimal privacy in the sense of Shokri et al. Furthermore, we propose a method
to reduce the number of constraints of the linear program from cubic to
quadratic, maintaining the privacy guarantees and without affecting
significantly the utility of the generated mechanism. This reduces considerably
the time required to solve the linear program, thus enlarging significantly the
location sets for which the optimal mechanisms can be computed.Comment: 13 page
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Older female mice lacking triggering recepter expressed on myeloid cells-2 have worse post-stroke neurological function and enhanced pro-inflammatory responses
Higher Order Corrections to Density and Temperature of Fermions from Quantum Fluctuations
A novel method to determine the density and temperature of a system based on
quantum Fermionic fluctuations is generalized to the limit where the reached
temperature T is large compared to the Fermi energy {\epsilon}f . Quadrupole
and particle multiplicity fluctuations relations are derived in terms of T .
The relevant Fermi integrals are numerically solved for any values of T and
compared to the analytical approximations. The classical limit is obtained, as
expected, in the limit of large temperatures and small densities. We propose
simple analytical formulas which reproduce the numerical results, valid for all
values of T . The entropy can also be easily derived from quantum fluctuations
and give important insight for the behavior of the system near a phase
transition. A comparison of the quantum entropy to the entropy derived from the
ratio of the number of deuterons to neutrons gives a very good agreement
especially when the density of the system is very low
Short-time critical dynamics at perfect and non-perfect surface
We report Monte Carlo simulations of critical dynamics far from equilibrium
on a perfect and non-perfect surface in the 3d Ising model. For an ordered
initial state, the dynamic relaxation of the surface magnetization, the line
magnetization of the defect line, and the corresponding susceptibilities and
appropriate cumulant is carefully examined at the ordinary, special and surface
phase transitions. The universal dynamic scaling behavior including a dynamic
crossover scaling form is identified. The exponent of the surface
magnetization and of the line magnetization are extracted. The impact
of the defect line on the surface universality classes is investigated.Comment: 11figure
Auxiliary potential in no-core shell-model calculations
The Lee-Suzuki iteration method is used to include the folded diagrams in the
calculation of the two-body effective interaction between
two nucleons in a no-core model space. This effective interaction still depends
upon the choice of single-particle basis utilized in the shell-model
calculation. Using a harmonic-oscillator single-particle basis and the
Reid-soft-core {\it NN} potential, we find that overbinds
^4\mbox{He} in 0, 2, and model spaces. As the size of the
model space increases, the amount of overbinding decreases significantly. This
problem of overbinding in small model spaces is due to neglecting effective
three- and four-body forces. Contributions of effective many-body forces are
suppressed by using the Brueckner-Hartree-Fock single-particle Hamiltonian.Comment: 14 text pages and 4 figures (in postscript, available upon request).
AZ-PH-TH/94-2
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