Comprehensive entropy weight observability-controllability risk analysis and its application to water resource decision-making

Decision making for water resource planning is often related to social, economic and environmental factors. There are various methods for making decisions about water resource planning alternatives and measures with various shortcomings. A comprehensive entropy weight observability-controllability risk analysis approach is presented in this study. Computing methods for entropy weight (EW) and subjective weight (SW) are put forward based on information entropy theory and experimental psychology principles, respectively. Comprehensive weight (CW) consisting of EW and SW is determined. The values of observability-controllability risk (Roc) and gain by comparison (Gbc) are obtained based on the CWs. The quantitative analysis of alternatives and measures is achieved based on Roc and Gbc. A case study on selection of water resource planning alternatives and measures in the Yellow River Basin, China, was performed. Results demonstrate that the approach presented in this study can achieve optimal decision-making results

Impurity states in d-wave superconductors with a competing antiferromagnetic interaction

Impurity states in d-wave superconductors with a competing antiferromagnetic (AF) order are investigated by solving the Bogoliubov-de Gennes equations. The potential scattering (PS) model with moderate strength and the Anderson impurity (AI) model with on-site hybridization are employed to describe the weak impurities. In zero external field, the impurity-induced AF order is rather weak and both models are able to give rise to impurity resonant states with close energy and similar profile of the local density of states. In the mixed state, the effect of magnetic-field-induced AF order on the impurity quasiparticle excitation is also examined. We find that the response of the impurity state to the presence of a local AF order is quite different for the two impurity models when a superconducting vortex is pinned by the impurity. For the PS model, the impurity resonance is subtly dependent on the sign and strength of the scattering potential, while for the AI model in the strong hybridization regime, the low-lying resonance is pinned near the Fermi level within the small gap opened by the AF order and is insensitive to the strength of the coupling between the impurity spin and the conduction electron. Based on our numerical results, we think that the two models give rise to different behaviors of the impurity resonances for both the nickel and zinc impurities in the magnetic field and the prospective scanning tunneling microscopic observation might give a clue to the dominant mechanism of the impurity states in the high-T c cuprates.published_or_final_versio

Electronic structure of the vortex lattice of d-, d+is-, and dx2-y2+idxy-wave superconductors

On the basis of the self-consistent Bogoliubov-de Gennes equations and a tight-binding lattice model, we investigate the quasiparticle spectrum of vortex-lattice state in pure d-, mixed d+is, and dx2-y2+idxy-wave superconductors. For a d-wave case, the local density of states (LDOS) at the vortex core shows a multipeak structure, and the positions of peaks as well as the width of splitting between peaks are sensitively dependent on both the magnetic-field strength and the orientation of the vortex lattice. For the mixed d+is- and dx2-y2+idxy-wave pairing states, we observe a double-peak structure of the local density of states at vortex center, where the two peaks are asymmetrically situated around the Fermi energy. By taking into account the matrix-element effect, the local density of states appears to be qualitatively consistent with the scanning-tunneling-microscopy experimental data.published_or_final_versio

A Study of Knowledge Construction in Virtual Product User Communities

In this research the virtual product user community is defined as a producer sponsored customer aggregation existing on the Internet to share usage experience and to collaboratively find technical solutions to problems with specific brand products. Such groups have a variety of benefits to members and organisations, one being that they are a knowledge resource for product users to look for solutions to specific problems with products and identify how to use them effectively. They are also a platform for the producer to communicate with its customers, to collect market intelligence, and to incorporate users’ innovative insights and problem solving skills. However, how knowledge is constructed and shared in such groups has been rarely studied. Previous literature that focuses on cognitive development and critical thinking stages in a formal online learning context may offer some relevant insights and methodologies but requires translation to the new context, and is not likely to provide a comprehensive understanding of this area. Accordingly, this thesis aims to explore knowledge construction in virtual product user communities. The philosophical basis of the research design was constructivism and interpretivism. A qualitative research methodology was adopted. Dozens of discussion threads of theoretical interest were chosen from a typical virtual product user community on the Dell User Support Forum (and from the Dell Idea Storm Community) and were analyzed through a qualitative content analysis method. In addition, semi-structured interviews with 20 community members of the Dell User Support Forum were conducted via e-mail. A deductive thematic analysis method was used for analysing the interview transcripts. More threads were chosen from a range of other virtual product user communities for content analysis in order to explore the influences of attributes such as language, national culture and technology platform on knowledge construction. A new content analysis tool, which is based on a combination of prior codes and new categories identified from the data, was created, in order to analyze the knowledge construction embedded in the discussion of technical problems. The research identified five types of key knowledge construction episodes that make up the knowledge building process and which are characterised by low-level cognitive engagement. A knowledge construction model which represents knowledge building in reality was developed. Furthermore, problem description episodes, non-constructive episodes, and moderation episodes were identified and their relations clarified. The problem description episodes were found to facilitate knowledge construction by providing knowledge about the problem and knowledge about its context. Following from this the peer advisor could diagnose the cause of technical problems and propose tailored solutions ideas based on the users’ experiential knowledge. The moderation episode can offset the negative influence of non-constructive episodes, maintaining social order and promoting knowledge contribution. The findings illustrate that knowledge construction needs collective contribution through various types of participation by community members at different knowledge levels. The influences of contextual attributes of a virtual product user community, including communication technology, sponsorship, national language and culture, moderation, and discussion topics, on knowledge construction, were all explored in this research. Models of different types of knowledge transfer across the boundaries between the virtual product user community and the organization, highlighting the role of moderators, were constructed. Besides the above findings, this research identified and defined this specific type of online community on the Internet, i.e. the virtual product user community. In addition, it provided a content analysis tool which is tailored to the purpose of examining low-level critical knowledge construction, which complements existing analytical frameworks, derived from formal learning contexts. The study mainly contributes to the general area of information and knowledge management, specifically knowledge construction in the virtual product user community and other low-level cognitive engagement contexts. It provides a theoretical basis for practices in managing online communities, and offers useful suggestions for educators in designing and managing formal online learning communities

Competition between ferromagnetic metallic and paramagnetic insulating phases in manganites

La 0.67Ca 0.33Mn 1-xCu xO 3 (x=0 and 0.15) epitaxial thin films were grown on the (100) LaAlO 3 substrates, and the temperature dependence of their resistivity was measured in magnetic fields up to 12 T by a four-probe technique. We found that the competition between the ferromagnetic metallic (FM) and paramagnetic insulating (PI) phases plays an important role in the observed colossal magnetoresistance (CMR) effect. Based on a scenario that the doped manganites approximately consist of phase-separated FM and PI regions, a simple phenomenological model was proposed to describe the CMR effect. Using this model, we calculated the resistivity as functions of temperature and magnetic field. The model not only qualitatively accounts for some main features related to the CMR effect, but also quantitatively agrees with the experimental observations. © 2002 American Institute of Physics.published_or_final_versio

Hole dispersions in the G- and C-type orbital ordering backgrounds: Doped manganese oxides

In the framework of the linear spin-wave theory and orbital-charge separation, we calculate quasiparticle (QP) dispersions for two different antiferromagnetic orbital structures in the fully saturated spin phase of manganese oxides. Although with the same orbital wave excitations, the QP bands of C- and G-type orbital structures exhibit completely different shapes. The pseudogap observed in the density of states and spectral functions around ω=0 is related with the large antiferromagnetic orbital fluctuation. The minimal band energy for G-type is lower than that for C-type orbital order, while these band curves almost coincide in some momentum points. Larger energy splitting occurs between the two branches of k z=0 and k z=π when increasing the superexchange coupling J, suggesting that the orbital scattering plays an essential role in the QP dispersions. ©2000 The American Physical Society.published_or_final_versio

Effect of Al addition on the microstructure and electronic structure of HfO₂film

Author name used in this publication: P. F. LeeAuthor name used in this publication: J. Y. Dai2006-2007 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Human ether-à-go-go gene potassium channels are regulated by EGFR tyrosine kinase

Human ether á-go-go gene potassium channels (hEAG1 or Kv10.1) are expressed in brain and various human cancers and play a role in neuronal excitement and tumor progression. However, the functional regulation of hEAG channels by signal transduction is not fully understood. The present study was therefore designed to investigate whether hEAG1 channels are regulated by protein tyrosine kinases (PTKs) in HEK 293 cells stably expressing hEAG1 gene using whole-cell patch voltage-clamp, immunoprecipitation, Western blot, and mutagenesis approaches. We found that the selective epidermal growth factor receptor (EGFR) kinase inhibitor AG556 (10μM), but not the platelet growth factor receptor (PDGFR) kinase inhibitor AG1295 (10μM) or the Src-family inhibitor PP2 (10μM), can inhibit hEAG1 current, and the inhibitory effect can be reversed by the protein tyrosine phosphatase (PTP) inhibitor orthovanadate. Immunoprecipitation and Western blot analysis revealed that tyrosine phosphorylation level of hEAG1 channels was reduced by AG556, and the reduction was significantly countered by orthovanadate. The hEAG1 mutants Y90A, Y344A and Y485A, but not Y376A and Y479A, exhibited reduced response to AG556. Interestingly, the inhibition effect of AG556 was lost in triple mutant hEAG1 channels at Y90, Y344, and Y485 with alanine. These results demonstrate for the first time that hEAG1 channel activity is regulated by EGFR kinase at the tyrosine residues Tyr 90, Try 344, and Try 485. This effect is likely involved in regulating neuronal activity and/or tumor growth. © 2011 Elsevier B.V.postprin

Resistive switching and threshold switching behaviors in La 0.1Bi 0.9Fe 1-xCo xO 3 ceramics

The effects of cobalt doping on the electrical conductivity of La 0.1Bi 0.9Fe 1-xCo xO 3 (LBFCO, x=0, 0.01, 0.03) ceramics were investigated. It is found that the leakage current increases with cobalt dopant concentration in LBFCO. On the application of bias voltage LBFCO ceramics with cobalt doping exhibits resistive switching effects at room temperature and threshold switching effects at elevated temperatures (50°C and 80°C). X-ray photoelectron spectroscopy of LBFCO ceramics show that cobalt dopant is bivalent as an acceptor, which induces an enhancement of oxygen vacancy concentration in LBFCO ceramics. Possible mechanisms for both resistive switching and threshold switching effects are discussed on the basis of the interplay of bound ferroelectric charges and mobile charged defects. © 2012 American Institute of Physics.published_or_final_versio