bluuebunny/crossref_metadata_2025_split huggingface dataset:
Stability and stabilization in switched discrete‐time systems
Authors: Zhang Hui , Shi Yang , Mehr Aryan Saadat 
Published: February 2012

SUMMARYIn this paper, we investigate the stability and stabilization problem for discrete‐time switched systems. We consider a probabilistic case where the system is switched among different subsystems, and the probability of each subsystem being active is defined as its occurrence probability. The relationship between the developed model of the switched system and the Markovian jump system is analyzed. For a switched system with a known subsystem occurrence probabilities, we give a stochastic stability criterion in terms of a linear matrix inequality. Then, we extend the results to a more practical case where the subsystem occurrence probabilities of switching are known to be constant, but their specific values are only known with some uncertainty. A new iterative approach is employed to choose the switching law between the subsystems. For unstable switched systems, mode‐dependent state feedback and static output feedback controllers are developed to achieve the stabilization objective. Finally, several simulation examples are presented to show the efficacy of the proposed criteria and methods. Copyright © 2012 John Wiley & Sons, Ltd.
Biofunctional Silk/Neuron Interfaces
Authors: Benfenati Valentina , Stahl Katja , Gomis‐Perez Carolina , Toffanin Stefano , Sagnella Anna , Torp Reidun , Kaplan David L. , Ruani Giampiero , Omenetto Fiorenzo G. , Zamboni Roberto , Muccini Michele 
Published: February 2012

AbstractSilk fibroin (SF) is a biocompatible and slowly biodegradable material with excellent mechanical properties and huge potential for use as biofunctional interface in electronic devices that aim to stimulate and control neural network activity and peripheral nerve repair. It is shown that SF films act as material interfaces that support the adherence and neurite outgrowth of dorsal root ganglion (DRG) neurons and preserve neuronal functions. Silk films preserve the capability of neuronal cells to fire and DRG neurons on silk films retain the intracellular free Ca2+ concentration ([Ca2+]i) response to capsaicin, a typical noxious stimulus for this neuronal culture model. It is also demonstrated that nerve growth factor (NGF)‐functionalized silk films promote neurite outgrowth and modulate functional properties of DRG neurons. The results show that silk preserves DRG neuronal physiology and is a promising biomaterial platform for the future development of devices with goals including functional recovery of injured neurons, neurite functional outgrowth in vitro, or functional electrostimulation in vivo.
Enhanced Energy Storage in Nanocomposite Capacitors through Aligned PZT Nanowires by Uniaxial Strain Assembly
Authors: Tang Haixiong , Lin Yirong , Sodano Henry A. 
Published: February 2012

AbstractThe design of nanocomposite capacitors poses certain challenges due to the reduced dielectric strength resulting from the integration of typically high dielectric fillers into the polymer. In prior efforts it was demonstrated that increasing of the filler could lead to energy‐storage densities up to 19.3% above the neat polymer. To further enhance the energy density, a novel strategy is developed to align nanowires in a thermoplastic matrix by uniaxial stretching assembly. It is demonstrated that the energy‐storage capability of the nanocomposite can be enhanced through the alignment of lead zirconate titanate (PZT) nanowires (NWs) in the direction of the applied electric field compared to randomly oriented samples. The maximum energy density of the nanocomposites is as high as 1.28 J cm−3 at a volume fraction of 40% PZT NWs (aspect ratio around 14) with axis of alignment in the direction of the electric field. The findings of this research could lead to broader interest due to development of the piezoceramic nanocomposites with enhanced dielectric properties for use in next‐generation energy‐storage and conversion devices.
Properties of strong off‐shore Borneo vortices: a composite analysis of flow pattern and composition as captured by ERA‐Interim
Authors: Braesicke Peter , See Hai Ooi , Abu Samah Azizan 
Published: February 2012

AbstractThe Borneo vortex (BV) is an important source of extreme weather for Malaysia. We describe climatological properties of strong off‐shore BVs using a potential vorticity (PV) threshold analysis of ERA‐Interim data. The composite BV at the location of most likely high PV occurrence has a warm core with enhanced specific humidity between 800 and 200 hPa, and a dry layer above. Two effects contribute to this structure: Air is vertically transported upwards in the BV whilst precipitating and the large scale flow in which the BV is embedded advect dry, ozone‐rich air from the equatorial tropical tropopause layer towards higher latitudes. Copyright © 2012 Royal Meteorological Society
Blocking roads to increase the evacuation efficiency
Authors: Huibregtse Olga , Hegyi Andreas , Hoogendoorn Serge 
Published: February 2012

SUMMARYIn order to evacuate as many people as possible in case of an approaching disaster, evacuation plans have to be made in advance. These plans usually consist of optimized traffic flows. Theoretically, these flows lead to an efficient evacuation, but in practice evacuees will most probably not behave like these flows without any intervention. This difference is partly caused by evacuees using roads that are unused in the optimized traffic flows case. In this paper, a new approach is investigated that can be applied to approach these flows during an evacuation: blocking the roads (i.e., making the roads inaccessible) that have a flow equal to zero in the optimal traffic flows. This approach is expected to be effective because the people are forced to behave in the direction of the optimized traffic flows. In a case study, this approach turns out to be effective. For two different cases, the efficiency of the evacuation (a function of the arrivals) improves with respectively 10.0% and 13.4% when the zero‐flow links are blocked compared with an evacuation without any intervention. Copyright © 2012 John Wiley & Sons, Ltd.
A probability model and sampling algorithm for the inter‐day stochastic traffic assignment problem
Authors: Wei Chong , Asakura Yasuo , Iryo Takamasa 
Published: February 2012

SUMMARYIn this study, we consider that inter‐day traffic flow fluctuations in a network are caused by stochastic travel behavior. We treat route traffic flows at each time interval as random variables. Therefore, the solution of the stochastic assignment problem should be the conditional joint probability distribution of the route flows given that the network is in stochastic user equilibrium. We formulate the conditional joint distribution and develop a Gibbs sampler to draw samples from the conditional joint distribution. The characteristics of the route flows at each time interval during the time horizon can be estimated on the basis of the simulated samples. Copyright © 2012 John Wiley & Sons, Ltd.
Trip generation modeling using data collected in single and repeated cross‐sectional surveys
Authors: Mwakalonge Judith L. , Badoe Daniel A. 
Published: February 2012

SUMMARYThe majority of US metropolitan regions still use the four‐step urban transportation modeling system to develop their travel forecasts. Trip generation, the first step of this system, has as objective of predicting the expected total travel demand in a region. The commonly used methods in planning practice for predicting this expected total travel demand typically use only the most recent cross‐sectional data available from a study region for model development, which ties the resulting travel‐forecast model to the economic environment prevailing at the time of data collection. Applying such models to generate forecasts of travel in economic environments significantly different from those embodied in the estimated model parameters could result in greater errors than would otherwise be the case.To address the aforementioned problem, this paper proposes the development of trip generation models estimated on multiple independent cross‐sectional datasets collected in the same urban region but at different times representing different economic environments. Data used in the research were collected in cross‐sectional household travel behavior surveys undertaken in the Greater Toronto Area, Canada in 1986, 1996, 2001, and 2006.The results lead to the conclusion that well‐specified models, estimated on pooled multiple cross‐sectional datasets, yield travel predictions in the base and horizon years, respectively, that have smaller error compared with corresponding travel predictions generated with single cross‐sectional models. Copyright © 2012 John Wiley & Sons, Ltd.
Identification of the First Known Inhibitors of O‐Acetylpeptidoglycan Esterase: A Potential New Antibacterial Target
Authors: Pfeffer John M. , Clarke Anthony J. 
Published: February 2012

AbstractThe O‐acetylation of peptidoglycan (PG) is now known to occur in 53 species, including numerous human pathogens such as, Staphylococcus aureus, Bacillus anthracis, species of Enterococcus, Campylobacter jejuni, Helicobacter pylori, Neisseria gonorrhoeae and N. meningitidis. This modification, which occurs at the C‐6 hydroxyl of N‐acetylmuramoyl residues within PG, serves to regulate autolytic activity during PG metabolism and contributes to pathogenesis and persistence within a host. O‐Acetylpeptidoglycan esterase (Ape) was recently discovered as an enzyme responsible for the removal of O‐acetyl groups from PG, thus permitting the continued maintenance and metabolism of the sacculus. Recombinant Ape1 from N. gonorrhoeae was purified to apparent homogeneity and optimal storage conditions for the enzyme were determined. Using 4‐methylumbelliferyl acetate as substrate, a fluorogenic assay amenable for the high‐throughput screening for potential inhibitors was developed and Ape1 was screened against a subset of compounds of the Canadian Compound Collection. The overall Z′ score for the screen was 0.62, indicative of a well‐suited assay with a sufficient signal window, and the threshold was set at 65 %. After eliminating a number of false‐positives, seven compounds were identified as true inhibitors of Ape1, the first to be identified for this class of enzyme. Dose–response curves were generated leading to the identification of five of these compounds with IC50 values ranging between 0.3 and 23 μM. Of these, purpurin was selected for further analysis and it was found to inhibit the growth of both Gram‐positive and Gram‐negative bacteria that produce both O‐acetylated PG and Ape.
Structure–Activity Relationships of Organofluorine Inhibitors of β‐Amyloid Self‐Assembly
Authors: Török Béla , Sood Abha , Bag Seema , Kulkarni Aditya , Borkin Dmitry , Lawler Elizabeth , Dasgupta Sujaya , Landge Shainaz , Abid Mohammed , Zhou Weihong , Foster Michelle , LeVine Harry , Török Marianna 
Published: February 2012

AbstractA broad group of structurally diverse small organofluorine compounds were synthesized and evaluated as inhibitors of β‐amyloid (Aβ) self‐assembly. The main goal was to generate a diverse library of compounds with the same functional group and to observe general structural features that characterize inhibitors of Aβ oligomer and fibril formation, ultimately identifying structures for further focused inhibitor design. The common structural motifs in these compounds are CF3‐C‐OH and CF3‐C‐NH groups that were proposed to be binding units in our previous studies. A broad range of potential small‐molecule inhibitors were synthesized by combining various carbocyclic and heteroaromatic rings with an array of substituents, generating a total of 106 molecules. The compounds were tested by standard methods such as thioflavin‐T fluorescence spectroscopy for monitoring fibril formation, biotinyl Aβ1–42 single‐site streptavidin‐based assays for observing oligomer formation, and atomic force microscopy for morphological studies. These assays revealed a number of structures that show significant inhibition against either Aβ fibril or oligomer formation. A detailed analysis of the structure–activity relationship of anti‐fibril and ‐oligomer properties is provided. These data present further experimental evidence for the distinct nature of fibril versus oligomer formation and indicate that the interaction of the Aβ peptide with chiral small molecules is not stereospecific in nature.
Arc mRNA docks precisely at the base of individual dendritic spines indicating the existence of a specialized microdomain for synapse‐specific mRNA translation
Authors: Dynes Joseph L. , Steward Oswald 
Published: February 2012

AbstractArc (aka Arg 3.1) is induced by neural activity and learning experience. Arc mRNA is rapidly exported into dendrites where it localizes near activated synapses. By imaging green fluorescent protein (GFP)‐tagged mRNA in living neurons in culture, we show that fusion transcripts containing the Arc 3′UTR (untranslated region) localize with remarkable precision in a microdomain at the base of dendritic spines. Transcripts with the Arc 3′UTR that encode a reporter protein rather than Arc show precise localization. Localization persists in the presence of translation inhibitors, indicating that localization does not require ongoing translation. Similarly, polyribosome complexes remained stably positioned at spine bases in brain tissue treated with the translation inhibitor (puromycin) that releases ribosomes from mRNA. Single particle tracking revealed that Arc mRNA particles positioned at spine bases exhibited highly constrained submicron movements. These observations imply the existence of a microdomain at the spine base where Arc mRNA docks in association with a previously unknown mRNA‐binding structural element. J. Comp. Neurol., 520:3105–3119, 2012. © 2012 Wiley Periodicals, Inc.
A multilevel fault model for integrated parallel fault‐tolerant systems
Authors: Fechner Bernhard 
Published: February 2012

SUMMARYThe appearance of multithreaded, multicore, and manycore systems has led to a performance leap. Such systems are denoted as integrated, when there are electrical and physical dependencies between different functional units, that is, multiple cores integrated on a single die. Typically, such systems have a common, shared interface to the outside world, bearing the potential of a single point of failure. In this work, several questions concerning fault propagation shall be tackled. First, if one component within a core fails, how likely is a faulty behavior of other components on the same or other cores? Second, what is the overall reliability of such a system? It is important to answer these questions prior to an implementation, because the total costs of a reliable product shall be as small as possible. Our approach combines different abstraction levels in one multilevel fault model. The first stage is the physical level, covering the physical effects of a fault. Validation on this level can be omitted, if the modeling is precise enough. The second stage is a component and routing model where current is represented as logic value. The last level is the behavioral modeling of components by finite state machines. Because of the different number and nature of existing parallel systems, a theoretical approach is followed. The model can cover the whole range of parallel devices from field programmable gate arrays to multicore CPUs and manycore graphics processing units. Therefore, it can help to improve the reliability of current and future parallel fault‐tolerant systems by identifying the underlying bottlenecks. The function of the model is exemplarily shown by applying it to a field programmable gate array, identifying switchboxes as the main reliability bottleneck. Copyright © 2012 John Wiley & Sons, Ltd.
Lattice‐based signcryption
Authors: Li Fagen , Bin Muhaya Fahad T. , Khan Muhammad Khurram , Takagi Tsuyoshi 
Published: February 2012

SUMMARYSigncryption is a cryptographic primitive that performs simultaneously both the functions of digital signature and public‐key encryption, at a cost significantly lower than that required by the traditional signature‐ then‐encryption approach. In this paper, we provide a positive answer to the question of if it is possible to construct signcryption based on lattice problems. More precisely, we design an efficient signcryption scheme that can send a message of length l one time. We prove that the proposed scheme has the indistinguishability against adaptive chosen ciphertext attacks under the learning with errors assumption and strong unforgeability against adaptive chosen messages attacks under the inhomogeneous small integer solution assumption in the random oracle model. Copyright © 2012 John Wiley & Sons, Ltd.
Even‐order passive filters: Pascal versus Chebyshev
Authors: Dimopoulos Hercules G. 
Published: February 2012

ABSTRACTThe recently reported Pascal approximation with non‐equiripple magnitude response leads to transfer functions of order equal or comparable to that of the Chebyshev approximation, offering an alternative to the equiripple Chebyshev approximation. Both approximations can be used in passive filter design and have similar design limitations when the order turns out to be even. In this paper, these design issues are thoroughly addressed, and the exact conditions are set under which even‐order passive Chebyshev and Pascal filters cannot be directly synthesised and either the order has to be increased to the next odd integer value or the modified filter must be designed. Pascal approximation is used for the first time for the design of doubly resistively terminated passive LC filters, and it is shown that the even‐order design issue is much less restricting making Pascal superior to Chebyshev filters in that even‐order filters can be directly designed to meet specifications that cannot be met by Chebyshev filters of the same even order. The theoretical results are confirmed through several design examples. Copyright © 2012 John Wiley & Sons, Ltd.
Personally customizable content authoring service for Internet Protocol television subscribers
Authors: Kim Nac‐Woo , Lee Byung‐Tak , Kim Young‐Sun 
Published: February 2012

SUMMARYIn this paper, we propose a personally customizable content authoring service (C2Channel) using an Internet Protocol television (IPTV) platform, in which a user terminal such as a PC or set‐top box sends various kinds of multimedia files from a camera or camcorder to a remotely located authoring server (C2Channel server). The C2Channel server creates personalized content in real time by combining special effects with the multimedia files transmitted from the user terminal and then retransmits them to a predefined relevant service group as a personal IPTV channel through an IPTV network provider. This content authoring service supplies an automatic multimedia editing/composition service and offers unicast, multicast, and groupcast services for a large number of interested groups via an IPTV‐based real‐time media delivery platform (Open Live IPTV Engine [OLIVE]), in which a service management server is used for user identification through the IPTV personal channel. Because this platform uses a remote server resource when authoring personally customizable content, resources remaining at the user's terminal can be variously utilized. Copyright © 2012 John Wiley & Sons, Ltd.
Investigation on the evolutionary algorithms with their applications in MIMO detecting systems
Authors: Hei Yong‐Qiang , Li Xiao-Hui , Li Wen‐Tao 
Published: February 2012

SUMMARYIn this paper, with the purpose of integrating the advantages of both the genetic algorithm and the particle swarm optimization, a new genetic particle swarm optimization (GPSO) algorithm is proposed. Furthermore, these three evolutionary algorithms are successfully applied to address the MIMO detection problem. Simulation results reveal that the GPSO‐based detection algorithm takes much less population size and iteration number when compared with the particle swarm optimization‐based detection method and the genetic algorithm‐based detection method. Besides, when compared with the optimal maximum likelihood detection method, the GPSO‐based detection algorithm can strike a much better balance between the BER performance and the computational complexity. Copyright © 2012 John Wiley & Sons, Ltd.
Gamma random waypoint mobility model for wireless ad hoc networks
Authors: Sabah Nasser , Hocanin Aykut 
Published: February 2012

SUMMARYRandom waypoint (RWP) mobility model is widely used in ad hoc network simulation. The model suffers from speed decay as the simulation progresses and may not reach the steady state in terms of instantaneous average node speed. Furthermore, the convergence of the average speed to its steady state value is delayed. This usually leads to inaccurate results in protocol validation of mobile ad hoc networks modeling. Moreover, the probability distributions of speed vary over the simulation time, such that the node speed distribution at the initial state is different from the corresponding distribution at the end of the simulation. In order to overcome these problems, this paper proposes a modified RWP mobility model with a more precise distribution of the nodes' speed. In the modified model, the speeds of nodes are sampled from gamma distribution. The results obtained from both analysis and simulation experiments of the average speed and the density of nodes' speed indicate that the proposed gamma random waypoint mobility model outperforms the existing RWP mobility models. It is shown that a significant performance improvement in achieving higher steady state speed values that closely model the pre‐assumed average speeds are possible with the proposed model. Additionally, the model allows faster convergence to the steady state, and probability distribution of speed is steady over the simulation time. Copyright © 2012 John Wiley & Sons, Ltd.
Enhanced switch combining for spatial diversity with a switch window over correlated Nakagami‐m fading channels
Authors: Chau Yawgeng A. , Chen Yao‐Hua 
Published: February 2012

SUMMARYOn the basis of a mixture of the selection combining and switch‐and‐stay combining schemes, the enhanced switch combining (ESC) scheme is proposed for antenna diversity over multiple correlated Nakagami‐m fading channels, where a switch window with upper and lower switch thresholds are used. Compared with the existing select‐and‐stay combining or switch with post‐examining, the ESC scheme reduces simultaneous multiantenna observations and hence saves processing time and energy from multibranch observations, while achieving matched receiver performance. Thus, ESC also has better performance than switch‐and‐examine combining (SEC). To assess the reduction of simultaneous observations, a dual‐observation rate is defined. Moreover, the ESC unifies some well‐known switch‐based combining schemes (for example selection combining, switch‐and‐stay combining, or SEC) in the sense that, by adjusting switch thresholds, these combining schemes become different special cases of ESC. The CDF, PDF, and moment generating function of the combined signal‐to‐noise ratio for ESC are derived for general fading channels. Then, the outage probability and the average BER of different binary modulations over correlated Nakagami‐m fading channels are evaluated. Numerical results from analysis and simulation are presented to demonstrate ESC performance. Copyright © 2012 John Wiley & Sons, Ltd.