Generalized hill climbing (GHC) algorithms provide a framework for modeling local search algorithms to address intractable discrete optimization problems. This paper introduces a measure for determining the expected number of iterations to visit a predetermined objective function level, given that an inferior objective function level has been reached in a finite number of iterations. A variation of simulated annealing (SA), termed static simulated annealing (S2A), is analyzed using this measure. S2A uses a fixed cooling schedule during the algorithm execution. Though S2A is probably nonconvergent, its finite-time performance can be assessed using the finite-time performance measure defined in this paper. 相似文献
We discuss the notion of spin squeezing considering two mutually exclusive classes of spin-s states, namely, oriented and non-oriented states. Our analysis shows that the oriented states are not squeezed while non-oriented
states exhibit squeezing. We also present a new scheme for construction of spin-s states using 2s spinors oriented along different axes. Taking the case of s=1, we show that the ‘non-oriented’ nature and hence squeezing arise from the intrinsic quantum correlations that exist among
the spinors in the coupled state. 相似文献
Generalized hill climbing (GHC) algorithms provide a framework for modeling local search algorithms for addressing intractable discrete optimization problems. Measures for assessing the finite-time performance of GHC algorithms have been developed using this framework, including the expected number of iterations to visit a predetermined objective function value level. This paper analyzes how the expected number of iterations to visit a predetermined objective function value level can be estimated for cyclical simulated annealing. Cyclical simulated annealing uses a cooling schedule that cycles through a set of temperature values. Computational results with traveling salesman problem instances taken from TSPLIB show how the expected number of iterations to visit solutions with predetermined objective function levels can be estimated for cyclical simulated annealing.AMS 2000 Subject Classification 90-08 Computational Methods: Local Search, 90C59 Heuristics: Simulated Annealing 相似文献
Starting from commercially available and relatively cheap chemicals first enantiopure dimethyl-substituted monoaza-18-crown-6 ether (R,R)-21 containing a diphenylamine unit was prepared, which was then transformed to dimethyl-substituted acridino-18-crown-6 ligand (R,R)-19 having an N-allyl-carbamoyl linker by several steps. The terminal double bond of the latter made possible to attach (R,R)-19 to γ-mercaptopropyl-functionalized spherical HPLC quality silica gel obtaining a new chiral stationary phase (R,R)-CSP-37. Based on electronic circular dichroism (ECD) studies the N-allyl-carbamoyl group attached to the acridine ring of the chiral host (R,R)-19 does weaken exciton interaction between the host and guest molecules, but does not destroy the discriminating power of the chiral host. An HPLC column filled with (R,R)-CSP-37 was tested for the enantioseparation of racemic 1-(1-naphthyl)- and 1-(2-naphthyl)ethylamine hydrogenperchlorates using isocratic conditions. 相似文献
The cell-free lysate of free-living amebae Naegleria gruberi and Naegleria fowleri were reported to elicit cytopathic effect in various cell lines that could be indefinitely transmitted by the culture media.
The causative agent showed sensitivity to treatments detrimental to proteins while resisted exposures damaging to nucleic
acids. Here we demonstrate that subsequent to exposure to N. gruberi lysate mild digestion with proteinase K reveals the presence of a protein band in HeLa cells absent from control cell lines.
Though the small quantity of this protein with enhanced resistance to proteinase K relative to the total protein content of
the sample has proved to date insufficient for its purification, we suppose that it is a human cellular protein that assumed
altered conformation in a prion-like fashion. The conformational conversion could have been trigerred by an ameba protein
in the lysate. In addition, we showed that HeLa cells treated with N. gruberi lysate display elevated cathepsin B activity which is assumed to be a secondary response to the accumulation of the proteinase
K-resistant protein. We propose that a number of degenerative sequelae following previous microbial infections in mammals
could have a similar pathomechanism. Moreover, epidemiological data strongly suggest that natural prion disease in sheep,
goat and cervids may also have an etiology linked to prior infection/colonization with a microbe, as it had already been proposed
by one of us. 相似文献
Summary: A new, simple, and effective synthetic method for the preparation of glucose‐terminated polyisobutylenes starting from the corresponding hydroxyl‐terminated polymers is reported. Detailed NMR and matrix‐assisted laser desorption/ionization mass spectrometric (MALDI‐TOF MS) investigations showed the exclusive presence of bis(glucopyranosyl) polyisobutylene. Dynamic light scattering (DLS) investigations of this polymer in solution in both tetrahydrofuran and water showed that microphase separation takes place by the formation of micelles and/or vesicles.
Representative structure of the glucose‐terminated polyisobutylenes synthesized here. 相似文献
The aim of this brief report is to study the behaviour of sheath structure in a multi-component plasma with dust-neutral collisions.
The plasma consists of electrons, ions, micron size negatively charged dust particles and neutrals. The sheath-edge potential
and sheath width are calculated for collisionally dominated sheath. Comparison of collisionless and collisionally dominated
sheath are made. 相似文献
The formerly discribed [1] unknown substance CHT 208, which was obtained as side product when 3β-benzoyloxy-Δ1-cholestene ( 3 ) was treated with ‘neutral’ activated alumina in an unpolar solvent, has been recognized as consisting of ca. 67% 3β-hydroxy-Δ1-cholestene ( 6 ) and of ca. 33% 3β-hydroxy-Δ1-cholestene ( 4 ) (molecular compound 2:1). Analogous treatment of 3β-chloro-Δ1-cholestene ( 5 ) with alumina yielded the same mixture of the allylic alcohols 4 and 6 as substitution products and of Δ1,3-cholestadiene ( 2 ) as elimination product in equal amounts. 相似文献