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It is shown in this paper that the problem of reducing the number of elements for multiple-pattern arrays can be solved by a sequence of reweighted l1 optimizations under multiple linear constraints. To do so, conjugate symmetric excitations are assumed so that the upper and lower bounds for each pattern can be formulated as linear inequality constraints. In addition, we introduce an auxiliary variable for each element to define the common upper bound of both the real and imaginary parts of multiple excitations for different patterns, so that only linear inequality constraints are required. The objective function minimizes the reweighted l1-norm of these auxiliary variables for all elements. Thus, the proposed method can be efficiently implemented by the iterative linear programming. For multiple desired patterns, the proposed method can select the common elements with multiple set of optimized amplitudes and phases, consequently reducing the number of elements. The radiation characteristics for each pattern, such as the mainlobe shape, response ripple, sidelobe level and nulling region, can be accurately controlled. Several synthesis examples for linear array, rectangular/triangular-grid and randomly spaced planar arrays are presented to validate the effectiveness of the proposed method in the reduction of the number of elements. [ABSTRACT FROM AUTHOR]

Efficient and unsplit-field finite-difference time-domain (FDTD) implementation of the complex frequency-shifted perfectly matched layer (CFS-PML), based on the digital signal processing (DSP) techniques and the material independence relations via applying the electric flux density (D) and the magnetic flux density (B), is proposed for truncating three dimensional FDTD computational domain entirely composed of dispersive material realized with a Drude model. The CFS-PML implementation is introduced based on the stretched coordinate PML (SC-PML) and the uniaxial anisotropic PML (UPML), respectively. The implementation of the proposed CFS-PML formulations is based on the SC-PML due to the fact that has advantage of simple implementation in the corners and the edges of the PML regions. Moreover, these proposed formulations are completely independent of the material properties of the FDTD computational domain and hence can be applied to truncate arbitrary media without any modification because of the D-B constitutive relations used in Maxwell's equations. Besides, the DSP techniques include the Bilinear Z-transform (BZT) method and the Matched Z-transform (MZT) method, respectively. However, from the point of view of the Courant-Friedrichs-Levy (CFL) condition, to the best of our knowledge, time step based on the BZT only needs to meet CFL condition, whereas time step based on the MZT method has to make it smaller for retaining stability and desirable accuracy. Consequently, the former one is introduced into the proposed formulations. A numerical example has been carried out in a three dimensional FDTD computational domain to validate the proposed formulations. It is clearly shown that the proposed formulations with CFS scheme are efficient in attenuating evanescent waves and reducing late-time reflections. [ABSTRACT FROM AUTHOR]

Efficient Z-transform implementation of the Complex Frequency-Shifted Perfectly Matched Layer (CFS-PML) using the D-B formulations are proposed to truncate open region multi-term dispersive Finite-Difference Time-Domain (FDTD) lattices. These formulations are independent of material properties of the FDTD domains and hence can be used for modeling general media because of the D-B constitutive relations. A Three-Dimensional (3-D) simulation of the two-term Lorentz dispersive FDTD domain has been carried out to demonstrate the validity of the proposed formulations. Furthermore, in order to show the validity of the proposed algorithm, the second 3D inhomogeneous problem has also been used for validating the proposed formulations. It is clearly shown that the new formulations with the CFS-PML scheme are efficient in attenuating evanescent waves and reducing late-time reflections. [ABSTRACT FROM AUTHOR]

Background: The equine infectious anemia virus (EIAV) is a lentivirus of the Retrovirus family, which causes persistent infection in horses often characterized by recurrent episodes of high fever. It has a similar morphology and life cycle to the human immunodeficiency virus (HIV). Its transmembrane glycoprotein, gp45 (analogous to gp41 in HIV), mediates membrane fusion during the infection. However, the post-fusion conformation of EIAV gp45 has not yet been determined. EIAV is the first member of the lentiviruses for which an effective vaccine has been successfully developed. The attenuated vaccine strain, FDDV, has been produced from a pathogenic strain by a series of passages in donkey dermal cells. We have previously reported that a V/I505T mutation in gp45, in combination with other mutations in gp90, may potentially contribute to the success of the vaccine strain. To this end, we now report on our structural and biochemical studies of the gp45 protein from both wide type and vaccine strain, providing a valuable structural model for the advancement of the EIAV vaccine. Results: We resolved crystal structures of the ecto-domain of gp45 from both the wild-type EIAV and the vaccine strain FDDV. We found that the V/I505T mutation in gp45 was located in a highly conserved d position within the heptad repeat, which protruded into a 3-fold symmetry axis within the six-helix bundle. Our crystal structure analyses revealed a shift of a hydrophobic to hydrophilic interaction due to this specific mutation, and further biochemical and virological studies confirmed that the mutation reduced the overall stability of the six-helix bundle in post-fusion conformation. Moreover, we found that altering the temperatures drastically affected the viral infectivity. Conclusions: Our high-resolution crystal structures of gp45 exhibited high conservation between the gp45/gp41 structures of lentiviruses. In addition, a hydrophobic to hydrophilic interaction change in the EIAV vaccine strain was found to modulate the stability and thermal-sensitivity of the overall gp45 structure. Our observations suggest that lowering the stability of the six-helix bundle (post-fusion), which may stabilizes the pre-fusion conformation, might be one of the reasons of acquired dominance for FDDV in viral attenuation. [ABSTRACT FROM AUTHOR]

This article presents an overview of the IEEE project 802.15.5 that targets providing mesh capabilities to both high-rate and low-rate wireless personal area networks. Low-rate mesh is built on IEEE 802.15.4 MAC, while high-rate mesh utilizes IEEE 802.15.3 MAC. We seek to share our insights and motivations of the approach adopted in the major components of the standard instead of presenting a Ia carte items drawn in the specification. We hope this article helps readers of the 802.15.5 standard to better understand the rationale and intent of the protocol design. [ABSTRACT FROM AUTHOR]

Over the past decade, wireless multihop ad hoc networks have received a tremendous amount of research focus, at the core of which lies the design problem for efficient routing algorithms to meet various scenarios and applications. The axiom, ‘One size doesn't fit all,’ continues to stand firmly to this day. In light of this, we introduce a new routing design concept — the component approach. We examine existing routing protocols and break them down into smaller building blocks, namely, routing components. The component analysis and classification results show that most routing protocols can be functionally decomposed into several basic routing components. This fact indicates that it is feasible to design a component-based routing (CBR) protocol. With a different realization for each basic routing component, it is expected that the routing behavior of CBR can be tailored to different application profiles and time-varying environment parameters at a reasonable cost. [ABSTRACT FROM AUTHOR]

This paper describes an AI planner assisted approach to generate test cases for system testing based on high level test objectives. We use four levels of test generation: the metaprocessor, the preprocessor, the AI planner, and the postprocessor levels. Test generation is based on an extended UML model of the system under test and a mapping of high-level test objectives into initial and goal conditions of the planner. Test objectives are derived from a series of interviews with professional testers. We suggest various options for test criteria related to test objectives. The AI planner was used to generate hundreds of test cases for a robot controlled tape silo. The planner generated tests within a reasonable time. It was successful for each test objective given. [ABSTRACT FROM AUTHOR]

The problem of synthesising a sparse linear array with multiple patterns is formulated as an extended reweighted l1-norm minimisation with multiple convex constraints. Synthesis results show that the proposed method can find the common sparse element positions with optimised excitations for multiple-pattern requirements, and the mainlobe, sidelobe as well as nulling region for each pattern can be accurately controlled. [ABSTRACT FROM AUTHOR]

The article offers information on a study regarding hidden charge density wave (CDW) states and insulator-to-metal transition after a pulsed femtosecond laser excitation in layered chalcogenide. It mentions that layered transition-metal dichalcogenides (TMDs) have been extensively studied because they exhibit a number of intriguing electronic phases from various textured charge density waves (CDWs).