Out of Context: NMDA Receptor Antagonism in the Avian 'Prefrontal Cortex' Impairs Context Processing in a Conditional Discrimination Task.

Processing of context information is implicated in prefrontal functions as response selection or attention. N-methyl-D-aspartate (NMDA) receptors in the mammalian prefrontal cortex (PFC) and in the nidopallium caudolaterale (NCL) of birds, the avian functional equivalent of the PFC, are involved in learning, which also requires processing of context. The authors investigated the role of NMDA receptors in the pigeon (Columba livia) NCL for context processing and response selection in a simultaneous-matching-to-sample task with 2 trial types, requiring either processing of context information, delivered by a conditional stimulus (context dependent), or only recall of a stimulus-response association (fixed response). The competitive NMDA antagonist DL-2-amino-5-phosphonovaleric acid impaired performance only in context-dependent trials. Therefore, NMDA receptors in the avian PFC participate in response selection requiring context processing rather than in response selection per se. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of deflection amplification factor in steel moment‐resisting frames

Steel moment‐resisting frames (SMRFs) are the most common type of structural systems used in steel structures. The first step of structural design for SMRFs starts with the selection of the structural sections on the basis of story drift limitation. ASCE 7 (2010) requires that the inelastic story drifts be obtained by multiplying the deflections determined by elastic analysis under design earthquake forces with a deflection amplification factor (C_d). For special moment‐resisting frames, C_d is given as 5.5 in ASCE 7 (2010). Lower C_d values will increase the overall inelastic response of the structure. On the other hand, the inelastic response of the structure is expected to be less severe when designed for higher C_d values. The performance objective is that the structure should sustain the inelastic deformation demand imposed due to design earthquake ground motions. This study aims at investigating the inelastic seismic response that low‐rise, medium‐rise and high‐rise SMRFs can experience under design earthquake ground motions and maximum considered earthquake (MCE) level ground motions and evaluating the deflection amplification factors (C_d) for SMRFs in a rational way. For this purpose, nonlinear dynamic time history and pushover analyses will be carried out on SMRFs with 4, 9 and 20 stories. The results indicate that the current practice for computing the inelastic story drifts for SMRFs is rational and the frames designed complying with the current code requirements can sustain the inelastic deformations imposed during design earthquake ground motions when seismically designed and detailed. Copyright © 2013 John Wiley & Sons, Ltd.     

A review: Fibre metal laminates,background, bonding types and applied test methods

During the past decades, increasing demand in aircraft industry for high-performance, lightweight structures have stimulated a strong trend towards the development of refined models for fibre-metal laminates (FMLs). Fibre metal laminates are hybrid composite materials built up from interlacing layers of thin metals and fibre reinforced adhesives. The most commercially available fibre metal laminates (FMLs) are ARALL (Aramid Reinforced Aluminium Laminate), based on aramid fibres, GLARE (Glass Reinforced Aluminium Laminate), based on high strength glass fibres and CARALL (Carbon Reinforced Aluminium Laminate), based on carbon fibres. Taking advantage of the hybrid nature from their two key constituents: metals (mostly aluminium) and fibre-reinforced laminate, these composites offer several advantages such as better damage tolerance to fatigue crack growth and impact damage especially for aircraft applications. Metallic layers and fibre reinforced laminate can be bonded by classical techniques, i.e. mechanically and adhesively. Adhesively bonded fibre metal laminates have been shown to be far more fatigue resistant than equivalent mechanically bonded structures.     

Node pacing for small optical RAM-buffered packet-switching networks

One of the difficulties with optical packet switched (OPS) networks is buffering optical packets in the network. The only available solution that can currently be used for buffering in the optical domain is using long fiber lines called fiber delay lines (FDLs), which have severe limitations. Moreover, the research on optical RAM presently being done is not expected to achieve a large capacity soon. However, the burstiness of Internet traffic causes high packet drop rates and low utilization in very small buffered OPS networks. We therefore propose a new node-based pacing algorithm for decreasing burstiness. We show that by applying some simple pacing at the edge or core backbone nodes, the performance of very small optical RAM buffered core OPS networks with variable-length packets can be notably increased.     

An experimental and three-dimensional numerical study of natural convection heat transfer between two horizontal parallel plates

In this study, experimental and three-dimensional numerical studies were performed to investigate the effects of plate spacing and temperature difference on natural convection between isothermally heated upward-facing lower horizontal plate and externally insulated horizontal upper plate. Air is used as the heat transfer medium. Rayleigh number varied in the 1108–2.339 × 10⁵ range. Several numerical simulations for three-dimensional steady laminar and turbulent flows heat transfer were carried out using a commercial CFD code Fluent 6.2. Results have shown that there is a good agreement between the numerical and present experimental results as well as with available data in literature.     

Weighted averaging for denoising with overcomplete dictionaries.

We consider the scenario where additive, independent, and identically distributed (i.i.d) noise in an image is removed using an overcomplete set of linear transforms and thresholding. Rather than the standard approach, where one obtains the denoised signal by ad hoc averaging of the denoised estimates provided by denoising with each of the transforms, we formulate the optimal combination as a conditional linear estimation problem and solve it for optimal estimates. Our approach is independent of the utilized transforms and the thresholding scheme, and as we illustrate using oracle-based denoisers, it extends established work by exploiting a separate degree of freedom that is, in general, not reachable using previous techniques. Our derivation of the optimal estimates specifically relies on the assumption that the utilized transforms provide sparse decompositions. At the same time, our work is robust as it does not require any assumptions about image statistics beyond sparsity. Unlike existing work, which tries to devise ever more sophisticated transforms and thresholding algorithms to deal with the myriad types of image singularities, our work uses basic tools to obtain very high performance on singularities by taking better advantage of the sparsity that surrounds them. With well-established transforms, we obtain results that are competitive with state-of-the-art methods.     

The influence of annealing on the crystallization and tribological behavior of MWNT/PEEK nanocomposites

In this study, annealing influence on crystallization and scratch behavior of neat and multi‐wall carbon nanotube (MWNT) reinforced poly(ether ether ketone) (PEEK) nanocomposites have been investigated. Crystallization behavior of normal and annealed samples was investigated by using differential scanning calorimeter (DSC). Scratch behavior of normal and annealed samples was investigated by using micro scratch tester. In DSC analysis, it was detected that, melting enthalpy of annealed neat PEEK was increased sharply when compared to neat PEEK. Melting enthalpies of annealed PEEK nanocomposites prepared with addition of up to 1 wt% MWNT were increased with a decreased trend. However, nanocomposites with higher contents of MWNTs (>1 wt%) were dramatically affected by annealing process and melting enthalpy decreased sharply. Friction coefficient values of “annealed MWNT reinforced PEEK composites” were found to be lower than “normal PEEK composites.” Annealing process affects scratch hardness of both annealed and MWNT reinforced PEEK. Annealed nanocomposites with various MWNT concentrations showed higher scratch hardness values than normal PEEK nanocomposites. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers     

Wake-up receivers for wireless sensor networks: benefits and challenges - [Accepted from open call]

For successful data delivery, the destination nodes should be listening to the medium to receive data when the sender node starts data communication. To achieve this synchronization, there are different rendezvous schemes, among which the most energy-efficient is utilizing wakeup receivers. Current hardware technologies of wake-up receivers enable us to evaluate them as a promising solution for wireless sensor networks. In this article the benefits achieved with wake-up receivers are investigated along with the challenges observed. In addition, an overview of state-of-the-art hardware and networking protocol proposals is presented. As wake-up receivers offer new opportunities, new potential application areas are also presented and discussed.     

Activation of glassy carbon electrodes by photocatalytic pretreatment

This paper describes a simple and rapid photocatalytic pretreatment procedure that removes contaminants from glassy carbon (GC) surfaces. The effectiveness of TiO₂ mediated photocatalytic pretreatment procedure was compared to commonly used alumina polishing procedure. Cyclic voltammetric and chronocoulometric measurements were carried out to assess the changes in electrode reactivity by using four redox systems. Electrochemical measurements obtained on photocatalytically treated GC electrodes showed a more active surface relative to polished GC. In cyclic voltammograms of epinephrine, Fe(CN)₆^3−/4− and ferrocene redox systems, higher oxidation and reduction currents were observed. The heterogeneous electron transfer rate constants (k^o) were calculated for Fe(CN)₆^3−/4− and ferrocene which were greater for photocatalytic pretreatment. Chronocoulometry was performed in order to find the amount of adsorbed methylene blue onto the electrode and was calculated as 0.34 pmol cm⁻² for photocatalytically pretreated GC. The proposed photocatalytic GC electrode cleansing and activating pretreatment procedure was more effective than classical alumina polishing.