9,308 research outputs found
Hybrid exciton-polaritons in a bad microcavity containing the organic and inorganic quantum wells
We study the hybrid exciton-polaritons in a bad microcavity containing the
organic and inorganic quantum wells. The corresponding polariton states are
given. The analytical solution and the numerical result of the stationary
spectrum for the cavity field are finishedComment: 3 pages, 1 figure. appear in Communications in Theoretical Physic
Cooperative co-evolution with differential grouping for large scale optimization
Cooperative co-evolution has been introduced into evolutionary algorithms with the aim of solving increasingly complex optimization problems through a divide-and-conquer paradigm. In theory, the idea of co-adapted subcomponents is desirable for solving large-scale optimization problems. However, in practice, without prior knowledge about the problem, it is not clear how the problem should be decomposed. In this paper, we propose an automatic decomposition strategy called differential grouping that can uncover the underlying interaction structure of the decision variables and form subcomponents such that the interdependence between them is kept to a minimum. We show mathematically how such a decomposition strategy can be derived from a definition of partial separability. The empirical studies show that such near-optimal decomposition can greatly improve the solution quality on large-scale global optimization problems. Finally, we show how such an automated decomposition allows for a better approximation of the contribution of various subcomponents, leading to a more efficient assignment of the computational budget to various subcomponents
An analysis of the inertia weight parameter for binary particle swarm optimization
In particle swarm optimization, the inertia weight is an important parameter for controlling its search capability. There have been intensive studies of the inertia weight in continuous optimization, but little attention has been paid to the binary case. This study comprehensively investigates the effect of the inertia weight on the performance of binary particle swarm optimization, from both theoretical and empirical perspectives. A mathematical model is proposed to analyze the behavior of binary particle swarm optimization, based on which several lemmas and theorems on the effect of the inertia weight are derived. Our research findings suggest that in the binary case, a smaller inertia weight enhances the exploration capability while a larger inertia weight encourages exploitation. Consequently, this paper proposes a new adaptive inertia weight scheme for binary particle swarm optimization. This scheme allows the search process to start first with exploration and gradually move towards exploitation by linearly increasing the inertia weight. The experimental results on 0/1 knapsack problems show that the binary particle swarm optimization with the new increasing inertia weight scheme performs significantly better than that with the conventional decreasing and constant inertia weight schemes. This study verifies the efficacy of increasing inertia weight in binary particle swarm optimization
Triaxially deformed relativistic point-coupling model for hypernuclei: a quantitative analysis of hyperon impurity effect on nuclear collective properties
The impurity effect of hyperon on atomic nuclei has received a renewed
interest in nuclear physics since the first experimental observation of
appreciable reduction of transition strength in low-lying states of
hypernucleus Li. Many more data on low-lying states of
hypernuclei will be measured soon for -shell nuclei, providing good
opportunities to study the impurity effect on nuclear low-energy
excitations. We carry out a quantitative analysis of hyperon impurity
effect on the low-lying states of -shell nuclei at the beyond-mean-field
level based on a relativistic point-coupling energy density functional (EDF),
considering that the hyperon is injected into the lowest
positive-parity () and negative-parity () states. We
adopt a triaxially deformed relativistic mean-field (RMF) approach for
hypernuclei and calculate the binding energies of hypernuclei as well
as the potential energy surfaces (PESs) in deformation plane.
We also calculate the PESs for the hypernuclei with good quantum
numbers using a microscopic particle rotor model (PRM) with the same
relativistic EDF. The triaxially deformed RMF approach is further applied in
order to determine the parameters of a five-dimensional collective Hamiltonian
(5DCH) for the collective excitations of triaxially deformed core nuclei.
Taking Mg and Si as examples, we analyse
the impurity effects of and on the low-lying states of
the core nuclei...Comment: 15 pages with 18 figures and 1 table (version to be published in
Physical Review C
Mitochondrial function assessed by 31P MRS and BOLD MRI in non-obese type 2 diabetic rats
The study aims to characterize ageâassociated changes in skeletal muscle bioenergetics by evaluating the response to ischemiaâreperfusion in the skeletal muscle of the GotoâKakizaki (GK) rats, a rat model of nonâobese type 2 diabetes (T2D). 31P magnetic resonance spectroscopy (MRS) and blood oxygen levelâdependent (BOLD) MRI was performed on the hindlimb of young (12 weeks) and adult (20 weeks) GK and Wistar (control) rats. 31PâMRS and BOLDâMRI data were acquired continuously during an ischemia and reperfusion protocol to quantify changes in phosphate metabolites and muscle oxygenation. The time constant of phosphocreatine recovery, an index of mitochondrial oxidative capacity, was not statistically different between GK rats (60.8 ± 13.9 sec in young group, 83.7 ± 13.0 sec in adult group) and their ageâmatched controls (62.4 ± 11.6 sec in young group, 77.5 ± 7.1 sec in adult group). During ischemia, baselineânormalized BOLDâMRI signal was significantly lower in GK rats than in their ageâmatched controls. These results suggest that insulin resistance leads to alterations in tissue metabolism without impaired mitochondrial oxidative capacity in GK rats
Distribution of Spectral Lags in Gamma Ray Bursts
Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray
bursts (GRBs) collected by the Burst and Transient Source Experiment on board
the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured
spectral lags in time between the low (25-55 keV) and high (110-320 keV) energy
bands of individual pulses contained in 64 multi-peak GRBs. We find that the
temporal lead by higher-energy gamma-ray photons (i.e., positive lags) is the
norm in this selected sample set of long GRBs. While relatively few in number,
some pulses of several long GRBs do show negative lags. This distribution of
spectral lags in long GRBs is in contrast to that in short GRBs. This apparent
difference poses challenges and constraints on the physical mechanism(s) of
producing long and short GRBs. The relation between the pulse peak count rates
and the spectral lags is also examined. Observationally, there seems to be no
clear evidence for systematic spectral lag-luminosity connection for pulses
within a given long GRB.Comment: 20 pages, 4 figure
An Ontology-based Two-Stage Approach to Medical Text Classification with Feature Selection by Particle Swarm Optimisation
© 2019 IEEE. Document classification (DC) is the task of assigning pre-defined labels to unseen documents by utilizing a model trained on the available labeled documents. DC has attracted much attention in medical fields recently because many issues can be formulated as a classification problem. It can assist doctors in decision making and correct decisions can reduce the medical expenses. Medical documents have special attributes that distinguish them from other texts and make them difficult to analyze. For example, many acronyms and abbreviations, and short expressions make it more challenging to extract information. The classification accuracy of the current medical DC methods is not satisfactory. The goal of this work is to enhance the input feature sets of the DC method to improve the accuracy. To approach this goal, a novel two-stage approach is proposed. In the first stage, a domain-specific dictionary, namely the Unified Medical Language System (UMLS), is employed to extract the key features belonging to the most relevant concepts such as diseases or symptoms. In the second stage, PSO is applied to select more related features from the extracted features in the first stage. The performance of the proposed approach is evaluated on the 2010 Informatics for Integrating Biology and the Bedside (i2b2) data set which is a widely used medical text dataset. The experimental results show substantial improvement by the proposed method on the accuracy of classification
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