Value of Indirect Hemagglutination and Coagglutination Tests for Serotyping Haemophilus parasuis

P. 880-882An indirect hemagglutination test (IHA) and a coagglutination test (CA) were evaluated using saline, boiled, and autoclaved extracts for serotyping Haemophilus parasuis. CA showed several cross-reactions, whereas IHA gave rise to specific reactions, with minor exceptions. IHA was further compared with the immunodiffusion test (the “gold standard”) for the serotyping of 67 field isolates. As a conclusion, IHA is recommended as a useful method for sensitive and specific serotyping of H. parasuisS

Using virtual potential fields for electric wheelchair guidance

TetraNauta is an electric wheelchair guidance system intended for people with heavy motion impairments (such as persons with tetraplegia). It is specially useful when impairments also affect wheelchair steering as it is able to automatically guide wheelchairs between different points in a known environment (a hospital, a school, etc), conditioned with track marks painted on the floor. It also provides a semiautomatic navigation mode, where control is shared between user and navigation system. It is intended for learning wheelchair manipulation and as an aid in places where navigation is difficult or dangerous (i.e. for crossing narrow corridors)

Identification and characterization of the TonB region and its role in transferrin-mediated iron acquisition in Haemophilus parasuis

12 p.Haemophilus parasuis is the causative agent of Glässer's disease, which is responsible for considerable economic losses in the pigrearing industry. The aim of the study reported here was the identification, sequencing and molecular characterization of the TonB region that includes tonB, exbBD, and tbpBA genes in H. parasuis. In addition, two fusion proteins were generated. One of them (pGEX-6P-1-GST-TbpB) contained the first 501 amino acids of H. parasuis TbpB protein, while the second (pBAD-Thio-TbpBV5- His) included the first 102 amino acids of H. parasuis TbpB N-terminus domain. A panel of 14 hybridomas secreting monoclonal antibodies was raised against the two recombinant TbpB fusion proteins. Furthermore, to assess whether the expression of the H. parasuis ExbB, TbpB, and TbpA proteins was upregulated under conditions of restricted availability of iron, a rabbit polyclonal antibody against H. parasuis TbpB-His fusion protein was produced. A rabbit polyclonal antibody against serotype 7 of Actinobacillus pleuropneumoniae ExbB and TbpA proteins was also used for the detection of the homologous proteins in H. parasuis. Overall, the data indicate that H. parasuis, like other members of the Pasteurellaceae family, possesses the genetic elements of the TonB region for iron acquisition and the transferrin-binding proteins encoded under this region are upregulated under restricted iron availabilityS

A Dynamic Equilibrium View of Caching Systems

In this paper, we present a simple analytical study of caching systems based on the idea of dynamic equilibrium of cache blocks, assuming the Independent Reference Model (IRM) of references. This method allows us to obtain simple closedform expressions for parameters that are usually excluded from cache studies, such as the mean number of reads or writes per cache block while in the cache. We finally present some simulation results in order to validate the analysis.Ministerio de Educación y Ciencia TIN2006-15617- C03-03Junta de Andalucía P06-TIC-229

Experimental Characterization of IdleTones in Second-Order Bandpass ΣΔ Modulators

This paper analyses the tonal behaviour of the quantization noise in second-order bandpass ΣΔ modulators. The analysis performed for lowpass modulators is extended to the bandpass case. As a result, closed form expressions for the frequency of idle tones are derived for different cases regarding the signal center frequency position. All these results have been validated by measurements from a silicon prototype using fully differential switched-current circuits implemented in a standard 0.8μm CMOS technology.This work has been supported by the Spanish CICYT Project TIC 97-0580.Peer reviewe

A 0.35 μm CMOS 17-bit@40-kS/s cascade 2-1 ΣΔ modulator with programmable gain and programmable chopper stabilization

This paper describes a 0.35μm CMOS chopper-stabilized Switched-Capacitor 2-1 cascade ΣDelta; modulator for automotive sensor interfaces. For a better fitting to the characteristics of different sensor outputs, the modulator includes a programmable set of gains (x0.5, x1, x2, and x4) and a programmable set of chopper frequencies (fs/16, fs/8, fs/4 and fs/2). It has also been designed to operate within the restrictive environmental conditions of automotive electronics (-40°C, 175°C). The modulator architecture has been selected after an exhaustive comparison among multiple ΣΔM topologies in terms of resolution, speed and power dissipation. The design of the modulator building blocks is based upon a top-down CAD methodology which combines simulation and statistical optimization at different levels of the modulator hierarchy. The circuit is clocked at 5.12MHz and consumes, all together, 14.7mW from a single 3.3-V supply. Experimental measurements result in 99.77dB of Dynamic Range (DR), which combined with the gain programmability leads to an overall DR of 112dB. This puts the presented design beyond the state-of-the-art according with the existing bibliography

Analysis of error mechanisms in switched-current Sigma-Delta modulators

El pdf del artículo es la versión post-print.This paper presents a systematic analysis of the major switched-current (SI) errors and their influence on the performance degradation of ΣΔ Modulators (ΣΔMs). The study is presented in a hierarchical systematic way. First, the physical mechanisms behind SI errors are explained and a precise modeling of the memory cell is derived. Based on this modeling, the analysis is extended to other circuits of higher level in the modulator hierarchy such as integrators and resonators. After that, the study is extended to the modulator level, considering two fundamental architectures: a 2nd-order LowPass ΣΔM (2nd-LPΣΔM) and a 4th-order BandPass ΣΔM (4th-BPΣΔM). The noise shaping degradation caused by the linear part of SI errors is studied in the first part of the paper. This study classifies SI non-idealities in different categories depending on how they modify the zeroes of the quantization noise transfer function. As a result, closed-form expressions are found for the degradation of the signal-to-noise ratio and for the change of the notch frequency position in the case of 4th-BPΣΔMs. The analysis is treated considering both the isolated and the cumulative effect of errors. In the second part of the paper the impact of non-linear errors on the modulator performance is investigated. Closed-form expressions are derived for the third-order harmonic distortion and the third-order intermodulation distortion at the output of the modulator as a function of the different error mechanisms. In addition to the mentioned effects, thermal noise is also considered. The most significant noise sources of SI ΣΔMs are identified and their contributions to the input equivalent noise are calculated. All these analyses have been validated by SPICE electrical simulations at the memory cell level and by time-domain behavioural simulations at the modulator level. As an experimental illustration, measurements taken from a 0.8 μm CMOS SI 4th-BPΣΔM silicon prototype validate our approach.This work has been partially supported by the EU ESPRIT Program in the framework of the Project IST 2001-34283 (TAMES-2), and by the Spanish CICYT under contract TIC2001-0929 (ADAVERE).Peer reviewe

Transfer of innovation - using research tools for engineering education

In this article, the authors show how, in the pursuit of research results, they can obtain excellent tools and data for engineering education. In particular, they describe one example of computer architecture in the Computer Engineering Degree Programme at the University of Cádiz in Spain. This research topic is of particular importance as it influences the execution of a range of the computer’s I/O operations, due to operations of peripherals and information devices, and determines processor performance. The simulator used in research and teaching in several engineering degree programmes at the University of Cádiz is also demonstrated in this article

Molecular characterization of Haemophilus parasuis ferric hydroxamate uptake (fhu) genes and constitutive expression of the FhuA receptor

P. 49-59Bacteria have evolved a set of highly specialized proteins to capture iron in irondepleted environments. The acquisition and uptake of iron present in the extracellular milieu of eukaryotic organisms is indispensable for the growth and survival of microbial pathogens in the course of infection. Haemophilus parasuis is the causative agent of Glässer disease, which is responsible for considerable financial losses in pig-rearing worldwide. To gain insight into the mechanisms involved in siderophore-mediated iron uptake in H. parasuis, genes in the H. parasuis ferric hydroxamate uptake (Fhu) region were amplified in the work being reported here. As has been described in A. pleuropneumoniae, an Fhu genomic region was also present in H. parasuis, being composed of four potential consecutive open reading frames (ORF) designated as fhuC, fhuD, fhuB, and fhuA, respectively. By immunoblotting, using a cross-reactive polyclonal antibody raised against Actinobacillus pleuropneumoniae FhuA protein, it was demonstrated that this protein was constitutively expressed in H. parasuis and its level of expression was not modified under conditions of restricted iron availability. This is the first report describing the presence of the fhu genes in H. parasuis. Our results indicate that FhuA protein expression is not affected under ironrestricted conditions, however, it is one of the targets of the humoral immune responseS

TetraNauta: a intelligent wheelchair for users with very severe mobility restrictions

The TetraNauta project is a low cost, fully open steering system to allow people with heavy motor impairments to move in a known environments (hospitals, schools, home, etc.). It minimizes the steering effort, especially in long paths, while caring for user safety. Every TetraNauta wheelchair has a general map of the environment wherein it navigates in automatic mode. It also knows its actual position in the map using on-board sensors that detect absolute positioning marks. The system consists of a traffic management subsystem and wheelchair motion control subsystem. Virtual potential fields as a tool for implementing automatic guidance in the intelligent electric wheelchair are considere