Simplicial gauge theory on spacetime

We define a discrete gauge-invariant Yang-Mills-Higgs action on spacetime simplicial meshes. The formulation is a generalization of classical lattice gauge theory, and we prove consistency of the action in the sense of approximation theory. In addition, we perform numerical tests of convergence towards exact continuum results for several choices of gauge fields in pure gauge theory.Comment: 18 pages, 2 figure

Spatial imaging of Zn and other elements in Huanglongbing-affected grapefruit by synchrotron-based micro X-ray fluorescence investigation

Huanglongbing (HLB) is a highly destructive, fast-spreading disease of citrus, causing substantial economic losses to the citrus industry worldwide. Nutrient levels and their cellular distribution patterns in stems and leaves of grapefruit were analysed after graft-inoculation with lemon scions containing 'Candidatus Liberibacter asiaticus' (Las), the heat-tolerant Asian type of the HLB bacterium. After 12 months, affected plants showed typical HLB symptoms and significantly reduced Zn concentrations in leaves. Micro-XRF imaging of Zn and other nutrients showed that preferential localization of Zn to phloem tissues was observed in the stems and leaves collected from healthy grapefruit plants, but was absent from HLB-affected samples. Quantitative analysis by using standard references revealed that Zn concentration in the phloem of veins in healthy leaves was more than 10 times higher than that in HLB-affected leaves. No significant variation was observed in the distribution patterns of other elements such as Ca in stems and leaves of grapefruit plants with or without graft-inoculation of infected lemon scions. These results suggest that reduced phloem transport of Zn is an important factor contributing to HLB-induced Zn deficiency in grapefruit. Our report provides the first in situ, cellular level visualization of elemental variations within the tissues of HLB-affected citrus. © 2014 © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology

Fault tolerant control using Gaussian processes and model predictive control

Abstract Essential ingredients for fault-tolerant control are the ability to represent system behaviour following the occurrence of a fault, and the ability to exploit this representation for deciding control actions. Gaussian processes seem to be very promising candidates for the first of these, and model predictive control has a proven capability for the second. We therefore propose to use the two together to obtain fault-tolerant control functionality. Our proposal is illustrated by several reasonably realistic examples drawn from flight control.This research was supported by EU Framework Programme 7, project 314544, RECONFIGURE: Reconfiguration of Control in Flight for Integral Global Upset Recovery, as well as the China Scholarship Council and the Cambridge Overseas Trust.This is the final published version. It first appeared at http://www.degruyter.com/view/j/amcs.2015.25.issue-1/amcs-2015-0010/amcs-2015-0010.xml

Application of a meshless method in electromagnetics

Author name used in this publication: S. L. HoAuthor name used in this publication: J. M. MachadoAuthor name used in this publication: H. C. Wong2001-2002 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

A modified ant colony optimization algorithm modeled on tabu-search methods

Author name used in this publication: S. L. Ho2005-2006 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Flexible coping psychotherapy for functional dyspeptic patients: A randomized, controlled trial

OBJECTIVE: This study tested the efficacy of a new psychotherapy, flexible coping psychotherapy (FCP), specifically designed for enhancing coping flexibility of patients with functional dyspepsia (FD). The design of this psychotherapy is based on the general cognitive-behavioral model and previous findings on FD. METHODS: We adopted a randomized, controlled design to examine the differences between the target (FCP) and control (supportive psychotherapy [SPP]) conditions. Coping flexibility and outcome measures reported by 75 Chinese FD patients (18-65 years; 35% men) were assessed before and 12 months after treatment. RESULTS: Results revealed that participants who received the FCP reported an increase in coping flexibility as well as reductions in self-rated dyspeptic symptom severity (SDSS), gastroenterologist-rated dyspeptic symptom severity, and anxiety levels (p values <.01). Participants who received the SPP reported reductions in SDSS and anxiety levels (p values <.0001). Although both groups reported a decrease in SDSS, only the SDSS level of the FCP group was comparable to that of a healthy community sample (p = .28). CONCLUSIONS: These findings suggest that FCP is a potentially effective intervention for treating FD symptoms. Its effectiveness may be attributable to the specific components of FCP rather than common psychotherapeutic factors such as emotional support and empathy per se. Copyright © 2007 by American Psychosomatic Society.postprin

Systems approaches and algorithms for discovery of combinatorial therapies

Effective therapy of complex diseases requires control of highly non-linear complex networks that remain incompletely characterized. In particular, drug intervention can be seen as control of signaling in cellular networks. Identification of control parameters presents an extreme challenge due to the combinatorial explosion of control possibilities in combination therapy and to the incomplete knowledge of the systems biology of cells. In this review paper we describe the main current and proposed approaches to the design of combinatorial therapies, including the empirical methods used now by clinicians and alternative approaches suggested recently by several authors. New approaches for designing combinations arising from systems biology are described. We discuss in special detail the design of algorithms that identify optimal control parameters in cellular networks based on a quantitative characterization of control landscapes, maximizing utilization of incomplete knowledge of the state and structure of intracellular networks. The use of new technology for high-throughput measurements is key to these new approaches to combination therapy and essential for the characterization of control landscapes and implementation of the algorithms. Combinatorial optimization in medical therapy is also compared with the combinatorial optimization of engineering and materials science and similarities and differences are delineated.Comment: 25 page

Secure pseudo-random linear binary sequences generators based on arithmetic polynoms

We present a new approach to constructing of pseudo-random binary sequences (PRS) generators for the purpose of cryptographic data protection, secured from the perpetrator's attacks, caused by generation of masses of hardware errors and faults. The new method is based on use of linear polynomial arithmetic for the realization of systems of boolean characteristic functions of PRS' generators. "Arithmetizatio" of systems of logic formulas has allowed to apply mathematical apparatus of residue systems for multisequencing of the process of PRS generation and organizing control of computing errors, caused by hardware faults. This has guaranteed high security of PRS generator's functioning and, consequently, security of tools for cryptographic data protection based on those PRSs

Superfluid vs Ferromagnetic Behaviour in a Bose Gas of Spin-1/2 Atoms

We study the thermodynamic phases of a gas of spin-1/2 atoms in the Hartree-Fock approximation. Our main result is that, for repulsive or weakly-attractive inter-component interaction strength, the superfluid and ferromagnetic phase transitions occur at the same temperature. For strongly-attractive inter-component interaction strength, however, the ferromagnetic phase transition occurs at a higher temperature than the superfluid phase transition. We also find that the presence of a condensate acts as an effective magnetic field that polarizes the normal cloud. We finally comment on the validity of the Hartree-Fock approximation in describing different phenomena in this system.Comment: 10 pages, 2 figure