1,461 research outputs found
Computing by nowhere increasing complexity
A cellular automaton is presented whose governing rule is that the Kolmogorov
complexity of a cell's neighborhood may not increase when the cell's present
value is substituted for its future value. Using an approximation of this
two-dimensional Kolmogorov complexity the underlying automaton is shown to be
capable of simulating logic circuits. It is also shown to capture trianry logic
described by a quandle, a non-associative algebraic structure. A similar
automaton whose rule permits at times the increase of a cell's neighborhood
complexity is shown to produce animated entities which can be used as
information carriers akin to gliders in Conway's game of life
Near-Perfect Correlation of the Resistance Components of Mesoscopic Samples at the Quantum Hall Regime
We study the four-terminal resistance fluctuations of mesoscopic samples near
the transition between the and the quantum Hall states. We
observe near-perfect correlations between the fluctuations of the longitudinal
and Hall components of the resistance. These correlated fluctuations appear in
a magnetic-field range for which the two-terminal resistance of the samples is
quantized. We discuss these findings in light of edge-state transport models of
the quantum Hall effect. We also show that our results lead to an ambiguity in
the determination of the width of quantum Hall transitions.Comment: As publishe
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Allocating Security Expenditures under Knightian Uncertainty: an Info-Gap Approach
We apply the information gap approach to resource allocation under Knightian (non-probabilistic) uncertainty in order to study how best to allocate public resources between competing defense measures. We demonstrate that when determining the level and composition of defense spending in an environment of extreme uncertainty vis-a-vis the likelihood of armed conflict and its outcomes, robust-satisficing expected utility will usually be preferable to expected utility maximization. Moreover, our analysis suggests that in environments with unreliable information about threats to national security and their consequences, a desire for robustness to model misspecification in the decision making process will imply greater expenditure on certain types of defense measures at the expense of others. Our results also provide a positivist explanation of how governments seem to allocate security expenditures in practice
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Allocating Security Expenditures under Knightian Uncertainty: an Info-Gap Approach
We apply the information gap approach to resource allocation under Knightian (non-probabilistic) uncertainty in order to study how best to allocate public resources betweencompeting defense measures. We demonstrate that when determining the level and composi-tion of defense spending in an environment of extreme uncertaintyvis-a-visthe likelihood ofarmed conflict and its outcomes, robust-satisficing expected utility will usually be preferableto expected utility maximisation. Moreover, our analysis suggests that in environments withunreliable information about threats to national security and their consequences, a desirefor robustness to model misspecification in the decision making process will imply greaterexpenditure on certain types of defense measures at the expense of others. Our results alsoprovide a positivist explanation of how governments seem to allocate security expendituresin practice
P143 Articular cartilage repair using in situ polymerizable hydrogel implant in osteochondral defects
Reversible surface aggregation in pore formation by pardaxin
The mechanism of leakage induced by surface active peptides is not yet fully understood. To gain insight into the molecular events underlying this process, the leakage induced by the peptide pardaxin from phosphatidylcholine/ phosphatidylserine/cholesterol large unilamellar vesicles was studied by monitoring the rate and extent of dye release and by theoretical modeling. The leakage occurred by an all-or-none mechanism: vesicles either leaked or retained all of their contents. We further developed a mathematical model that includes the assumption that certain peptides become incorporated into the vesicle bilayer and aggregate to form a pore. The current experimental results can be explained by the model only if the surface aggregation of the peptide is reversible. Considering this reversibility, the model can explain the final extents of calcein leakage for lipid/peptide ratios of > 2000:1 to 25:1 by assuming that only a fraction of the bound peptide forms pores consisting of M = 6 +/- 3 peptides. Interestingly, less leakage occurred at 43 degrees C, than at 30 degrees C, although peptide partitioning into the bilayer was enhanced upon elevation of the temperature. We deduced that the increased leakage at 30 degrees C was due to an increase in the extent of reversible surface aggregation at the lower temperature. Experiments employing fluorescein-labeled pardaxin demonstrated reversible aggregation of the peptide in suspension and within the membrane, and exchange of the peptide between liposomes. In summary, our experimental and theoretical results support reversible surface aggregation as the mechanism of pore formation by pardaxin
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Allocating Security Expenditures under Knightian Uncertainty: an Info-Gap Approach
We apply the information gap approach to resource allocation under Knightian (non-probabilistic) uncertainty in order to study how best to allocate public resources between competing defense measures. We demonstrate that when determining the level and composition of defense spending in an environment of extreme uncertainty vis-a-vis the likelihood of armed conflict and its outcomes, robust-satisficing expected utility will usually be preferable to expected utility maximization. Moreover, our analysis suggests that in environments with unreliable information about threats to national security and their consequences, a desire for robustness to model misspecification in the decision making process will imply greater expenditure on certain types of defense measures at the expense of others. Our results also provide a positivist explanation of how governments seem to allocate security expenditures in practice
Two-Dimensional Electron Gas in InGaAs/InAlAs Quantum Wells
We designed and performed low temperature DC transport characterization
studies on two-dimensional electron gases confined in lattice-matched
InGaAs/InAlAs quantum wells grown by
molecular beam epitaxy on InP substrates. The nearly constant mobility for
samples with the setback distance larger than 50nm and the similarity between
the quantum and transport life-time suggest that the main scattering mechanism
is due to short range scattering, such as alloy scattering, with a scattering
rate of 2.2 ps. We also obtain the Fermi level at the
InGaAs/InAlAs surface to be 0.36eV above
the conduction band, when fitting our experimental densities with a
Poisson-Schr\"odinger model.Comment: Accepted in Applied Physics Letter
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