Plasma polypyrrole implants recover motor function in rats after spinal cord transection

We studied the use of three biocompatible materials obtained by plasma polymerization of pyrrole (PPy), pyrrole doped with iodine (PPy/I) and a copolymer formed with pyrrole and polyethylene glycol (PPy/PEG), implanted, separately, after a complete spinal cord transection in rats. Motor function assessed with the BBB scale and somatosensory evoked potentials (SEPs) in the implanted rats were studied. Results showed that the highest motor recovery was obtained in rats with PPy/I implants. They also showed a significant reduction in the latency of SEPs. Histological analyses showed no signs of implant rejection; on the contrary, implants based on PPy improved the SEPs conduction and motor function after lesion.     

Remote Detection of a Frequency Jammer Operating in the Down Link of a Cellular System

The authors propose a novel method to evaluate the interference conditions in a cellular network. The method takes advantage of the signal strength and quality measurements available at a Base Station. Measurements from both up-link and down-link are jointly processed to remotely detect the presence of a medium-range frequency jammer and other situations involving abnormal interference levels, as a malfunctioning of the power control algorithm, a bad radio optimization and planning or an outer interference, among others. The proposed method can be adapted to any cellular system. In this paper we focus on its application to GSM/GPRS system. We include some experiments where real cell data recordings were analyzed.     

Production of phytosterol esters from soybean oil deodorizer distillates

Enzymatic esterification and supercritical fluid extraction was used to produce phytosterol esters from soybean oil deodorizer distillates. The raw material was first subjected to a two‐step enzymatic reaction; the product obtained mainly comprised fatty acid ethyl esters, tocopherols and phytosterol esters, together with minor amounts of squalene, free fatty acids, free sterols and triacylglycerols. The phytosterol esters were then purified from this mixture using supercritical carbon dioxide. Experimental extractions were carried out in an isothermal countercurrent column (without reflux), with pressures ranging from 200 to 280 bar, temperatures of 45–55 °C and solvent‐to‐feed ratios from 15 to 35 kg/kg. Using these extraction conditions, the fatty acid esters were completely extracted and, thus, the fractionation of tocopherols and phytosterol esters was studied. At 250 bar, 55 °C and a solvent‐to‐feed ratio of 35, the phytosterol esters were concentrated in the raffinate up to 82.4 wt‐% with satisfactory yield (72%).     

Experimental data and numerical modelling of 1.3 and 2.3 MW fires in a 20 m cubic atrium

Atria and large spaces are common architectonical features in modern buildings such as high rises, auditoria, warehouses, airports and mass transport stations among others. There is currently an international trend towards the performance-based design for fire safety of these building elements. This design process relies heavily on fire modelling but the knowledge in fire dynamics and the movement of smoke in atria and large spaces still presents some gaps. This paper aims at contributing to close these gaps and reports the three Murcia Atrium Fire Tests conducted in a 20 m cubic enclosure using pools of 1.3 and 2.3 MW. Detailed transient measurements of gas and wall temperatures, as well as pressure drop through the exhaust fans and airflow at the inlets were recorded. The study also includes the effect of the mechanical exhaust ventilation. Results have been compared with those predicted by the computational fluid dynamics (CFD) model Fire Dynamics Simulator FDSv4. In general terms, the comparisons between experiments and simulations show good agreement, especially in the far field of the plume, but the accuracy is poor at the lower plume region and near the flame.     

Device level communication libraries for high‐performance computing in Java

Since its release, the Java programming language has attracted considerable attention from the high‐performance computing (HPC) community because of its portability, high programming productivity, and built‐in multithreading and networking support. As a consequence, several initiatives have been taken to develop a high‐performance Java message‐passing library to program distributed memory architectures, such as clusters. The performance of Java message‐passing applications relies heavily on the communications performance. Thus, the design and implementation of low‐level communication devices that support message‐passing libraries is an important research issue in Java for HPC. MPJ Express is our Java message‐passing implementation for developing high‐performance parallel Java applications. Its public release currently contains three communication devices: the first one is built using the Java New Input/Output (NIO) package for the TCP/IP; the second one is specifically designed for the Myrinet Express library on Myrinet; and the third one supports thread‐based shared memory communications. Although these devices have been successfully deployed in many production environments, previous performance evaluations of MPJ Express suggest that the buffering layer, tightly coupled with these devices, incurs a certain degree of copying overhead, which represents one of the main performance penalties. This paper presents a more efficient Java message‐passing communications device, based on Java Input/Output sockets, that avoids this buffering overhead. Moreover, this device implements several strategies, both in the communication protocol and in the HPC hardware support, which optimizes Java message‐passing communications. In order to evaluate its benefits, this paper analyzes the performance of this device comparatively with other Java and native message‐passing libraries on various high‐speed networks, such as Gigabit Ethernet, Scalable Coherent Interface, Myrinet, and InfiniBand, as well as on a shared memory multicore scenario. The reported communication overhead reduction encourages the upcoming incorporation of this device in MPJ Express ( http://mpj‐express.org ). Copyright © 2011 John Wiley & Sons, Ltd.     

Probabilistic inverse problem to characterize tissue-equivalent material mechanical properties

The understanding of internal processes that affect the changes of consistency of soft tissue is a challenging problem. An ultrasound-monitoring Petri dish has been designed to monitor the evolution of relevant mechanical parameters during engineered tissue formation processes in real time. A better understanding of the measured ultrasonic signals required the use of numerical models of the ultrasound-tissue interactions. The extraction of relevant data and its evolution with sufficient sensitivity and accuracy is addressed by applying well-known signal processing techniques to both the experimental and numerically predicted measurements. In addition, a stochastic model-class selection formulation is used to rank which of the proposed interaction models are more plausible. The sensitivity of the system is verified by monitoring a gelation process.     

Study of peptide fingerprints of parasite proteins and drug-DNA interactions with Markov-Mean-Energy invariants of biopolymer molecular-dynamic lattice networks

Since the advent of Molecular Dynamics (MD) in biopolymers science with the study by Karplus et al. on protein dynamics, MD has become the by foremost well established, computational technique to investigate structure and function of biomolecules and their respective complexes and interactions. The analysis of the MD trajectories (MDTs) remains, however, the greatest challenge and requires a great deal of insight, experience, and effort. Here, we introduce a new class of invariants for MDTs based on the spatial distribution of Mean-Energy values ξ_k(L) on a 2D Euclidean space representation of the MDTs. The procedure forces one MD trajectory to fold into a 2D Cartesian coordinates system using a step-by-step procedure driven by simple rules. The ξ_k(L) values are invariants of a Markov matrix (¹Π), which describes the probabilities of transition between two states in the new 2D space; which is associated to a graph representation of MDTs similar to the lattice networks (LNs) of DNA and protein sequences. We also introduce a new algorithm to perform phylogenetic analysis of peptides based on MDTs instead of the sequence of the polypeptide. In a first experiment, we illustrate this algorithm for 35 peptides present on the Peptide Mass Fingerprint (PMF) of a new protein of Leishmania infantum studied in this work. We report, by the first time, 2D Electrophoresis isolation, MALDI TOF Mass Spectroscopy characterization, and MASCOT search results for this PMF. In a second experiment, we construct the LNs for 422 MDTs obtained in DNA-Drug Docking simulations of the interaction of 57 anticancer furocoumarins with a DNA oligonucleotide. We calculated the respective ξ_k(L) values for all these LNs and used them as inputs to train a new classifier with Accuracy = 85.44% and 84.91% in training and validation respectively. The new model can be used as scoring function to guide DNA-Drug Docking studies in drug design of new coumarins for PUVA therapy. The new phylogenetics analysis algorithms encode information different from sequence similarity and may be used to analyze MDTs obtained in Docking or modeling experiments for any classes of biopolymers. The work opens new perspective on the analysis and applications of MD in polymer sciences.     

Constant stress intensity factors through closed-loop control

A new way of obtaining a constant stress intensity factor is achieved for any test specimen geometry subjected to closed-loop control loading. In contrast to using only load or displacement control the method draws on combined feedback from both displacement and load sensing, reducing the variation in the stress intensity factor by two decades compared to that if tested under constant load or displacement. A change in the signal mix ratio for a rectangular compact tension specimen is equivalent to changing the angle of a tapered compact tension specimen. This method can eliminate the need for the use of ‘complex’ geometries or for geometries in which measured crack lengths are used in conjunction with a computer or some other means to adjust the loading continuously for achieving a constant stress intensity factor.     

Fourier analysis of semi-discrete and space-time stabilized methods for the advective-diffusive-reactive equation: I. SUPG

The goal of this paper is twofold. One the one side, the most common transient Galerkin and SUPG methods are analyzed for the one-dimensional advection-diffusion-reaction equation. The methods analyzed include semi-discrete, time-discontinuous space-time stabilized finite element methods and several predictor multi-corrector versions of them. On the other hand, in the framework of explicit predictor multi-corrector algorithms a novel treatment of the source terms is proposed and analyzed. The technique consists of the diagonally implicit treatment of the negative or dissipative source terms. This technique increases dramatically the phase and damping accuracy of classical explicit methods and, at the same time, removes the source terms from stability considerations for low viscosity flows, thus, leading to very economic procedures.