1,199 research outputs found
On Multistage Learning a Hidden Hypergraph
Learning a hidden hypergraph is a natural generalization of the classical
group testing problem that consists in detecting unknown hypergraph
by carrying out edge-detecting tests. In the given paper we
focus our attention only on a specific family of localized
hypergraphs for which the total number of vertices , the number of
edges , , and the cardinality of any edge ,
. Our goal is to identify all edges of by
using the minimal number of tests. We develop an adaptive algorithm that
matches the information theory bound, i.e., the total number of tests of the
algorithm in the worst case is at most . We also discuss
a probabilistic generalization of the problem.Comment: 5 pages, IEEE conferenc
Multipartite minimum uncertainty products
In our previous work we have found a lower bound for the multipartite
uncertainty product of the position and momentum observables over all separable
states. In this work we are trying to minimize this uncertainty product over a
broader class of states to find the fundamental limits imposed by nature on the
observable quantites. We show that it is necessary to consider pure states only
and find the infimum of the uncertainty product over a special class of pure
states (states with spherically symmetric wave functions). It is shown that
this infimum is not attained. We also explicitly construct a parametrized
family of states that approaches the infimum by varying the parameter. Since
the constructed states beat the lower bound for separable states, they are
entangled. We thus show that there is a gap that separates the values of a
simple measurable quantity for separable states from entangled ones and we also
try to find the size of this gap.Comment: 18 pages, 5 figure
Formation and stability of self-assembled coherent islands in highly mismatched heteroepitaxy
We study the energetics of island formation in Stranski-Krastanow growth
within a parameter-free approach. It is shown that an optimum island size
exists for a given coverage and island density if changes in the wetting layer
morphology after the 3D transition are properly taken into account. Our
approach reproduces well the experimental island size dependence on coverage,
and indicates that the critical layer thickness depends on growth conditions.
The present study provides a new explanation for the (frequently found) rather
narrow size distribution of self-assembled coherent islands.Comment: 4 pages, 5 figures, In print, Phys. Rev. Lett. Other related
publications can be found at http://www.fhi-berlin.mpg.de/th/paper.htm
Johnson-Kendall-Roberts theory applied to living cells
Johnson-Kendall-Roberts (JKR) theory is an accurate model for strong adhesion
energies of soft slightly deformable material. Little is known about the
validity of this theory on complex systems such as living cells. We have
addressed this problem using a depletion controlled cell adhesion and measured
the force necessary to separate the cells with a micropipette technique. We
show that the cytoskeleton can provide the cells with a 3D structure that is
sufficiently elastic and has a sufficiently low deformability for JKR theory to
be valid. When the cytoskeleton is disrupted, JKR theory is no longer
applicable
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