Dynamic Analysis of Epicyclic Gear Trains by Means of Computer Algebra

The paper illustrates the application of a systematic technique for thededuction of dynamic equations of epicyclic gear trains. The use of theproposed method is particularly amenable in conjuction with proceduresfor the computerized enumeration of geared kinematic chains. Thediscussed examples illustrate how the presented approach can be extendedfor computing the equivalent inertia of an epicyclic gear train or forthe stability analysis of 2 d.o.f. gear trains.     

Topographic visualization of prefix propagation in the internet

We propose a new metaphor for the visualization of prefixes propagation in the Internet. Such a metaphor is based on the concept of topographic map and allows to put in evidence the relative importance of the Internet Service Providers (ISPs) involved in the routing of the prefix. Based on the new metaphor we propose an algorithm for computing layouts and experiment with such algorithm on a test suite taken from the real Internet. The paper extends the visualization approach of the BGPlay service, which is an Internet routing monitoring tool widely used by ISP operators     

Problem solution sustenance in XCS: Markov chain analysis of niche support distributions and the impact on computational complexity

Michigan-style learning classifier systems iteratively evolve a distributed solution to a problem in the form of potentially overlapping subsolutions. Each problem niche is covered by subsolutions that are represented by a set of predictive rules, termed classifiers. The genetic algorithm is designed to evolve classifier structures that together cover the whole problem space and represent a complete problem solution. An obvious challenge for such an online evolving, distributed knowledge representation is to continuously sustain all problem subsolutions covering all problem niches, that is, to ensure niche support. Effective niche support depends both on the probability of reproduction and on the probability of deletion of classifiers in a niche. In XCS, reproduction is occurrence-based whereas deletion is support-based. In combination, niche support is assured effectively. In this paper we present a Markov chain analysis of the niche support in XCS, which we validate experimentally. Evaluations in diverse Boolean function settings, which require non-overlapping and overlapping solution structures, support the theoretical derivations. We also consider the effects of mutation and crossover on niche support. With respect to computational complexity, the paper shows that XCS is able to maintain (partially overlapping) niches with a computational effort that is linear in the inverse of the niche occurrence frequency.

Cerebrospinal fluid biomarkers in clinically isolated syndromes and multiple sclerosis

A panel of three cerebrospinal fluid (CSF) markers for clinically isolated syndromes (CIS) and multiple sclerosis (MS), based on SDS-PAGE, 2-D maps, and immunoblot results, is here proposed. No individual marker has any specificity, though, since they appear in a number of other neurological diseases. However the set of three, with the respective modulation sign (up-regulated or maintained at constant level), appears to be unique for MS. These proteins are: tau protein (levels remaining constant and undistinguishable from controls, contrary to up- and downregulation in other neurological disorders); 14-3-3 protein (strong upregulation of distinct isoforms) and cystatin C (changing in accordance to disease stage and progression). As an additional evidence, one can rely in the pattern of isoforms of 14-3-3, as obtained by 2-D maps and Western blot analysis: this pattern further distinguishes the variation of this protein from other neurological syndromes, notably sporadic Creutzfeldt-Jakob disease (sCJD), motor neuron diseases and other dementias. In contrast, a similar qualitative and quantitative upregulation of 14-3-3 is observed in Guillain-Barré syndrome (GBS), a demyelinating condition affecting the peripheral nervous system. To the best of our knowledge, this is the first time in which such a panel of biomarkers is reported in MS.     

The effect of sotalol hydrochloride therapy on atrial signal-averaged ECG in patients with paroxysmal atrial fibrillation

BACKGROUND: There has been a continuing public debate about assisted suicide and the proper role, if any, of physicians in this practice. Legislative bans and various forms of legalization have been proposed. METHODS: We mailed questionnaires to three stratified random samples of Michigan physicians in specialties likely to involve the care of terminally ill patients: 500 in the spring of 1994, 500 in the summer of 1994, and 600 in the spring of 1995. Similar questionnaires were mailed to stratified random samples of Michigan adults: 449 in the spring of 1994 and 899 in the summer of 1994. Several different questionnaire forms were used, all of which included questions about whether physician-assisted suicide should be banned in Michigan or legalized under certain conditions. RESULTS: Usable questionnaires were returned by 1119 of 1518 physicians eligible for the study (74 percent), and 998 of 1307 eligible adults in the sample of the general public (76 percent). Asked to choose between legalization of physician-assisted suicide and an explicit ban, 56 percent of physicians and 66 percent of the public support legalization, 37 percent of physicians and 26 percent of the public preferred a ban, and 8 percent of each group were uncertain. When the physicians were given a wider range of choices, 40 percent preferred legalization, 37 percent preferred "no law" (i.e., no government regulation), 17 percent favored prohibition, and 5 percent were uncertain. If physician-assisted suicide were legal, 35 percent of physicians said they might participate if requested--22 percent would participate in either assisted suicide or voluntary euthanasia, and 13 percent would participate only in assisted suicide. Support for physician-assisted suicide was lowest among the strongly religious. CONCLUSIONS: Most Michigan physicians prefer either the legalization of physician-assisted suicide or no law at all; fewer than one fifth prefer a complete ban on the practice. Given a choice between legalization and a ban, two thirds of the Michigan public prefer legalization and one quarter prefer a ban.     

Cellulosic materials: Structure and enzymatic hydrolysis relationships

Structural and morphological features of four different cellulosic materials have been deeped by X-ray, CP–MAS NMR, water retention, and specific surface area analysis. Hydrolysis time courses of two of these celluloses were followed by employing an enzymatic system consisting of a cellulase from Trichoderma viride and a cellobiase from Aspergillus niger. Experimental results were rationalized on the basis of a methematical model previously verified on the other two substrates. All the celluloses presented the same mechanistic framework involving product inhibitions. The most efficient pretreatment was found to be the dissolution of cellulosic material in the dimethyl sulfoxide–paraformaldehyde system and regeneration with ammonia. This treatment cancelled the memory of the initial structural order.     

Thermal cis-trans isomerization and photofading of some azo dyes in poly(ethylene terephthalate) matrices: A kinetic study

The thermal cis-trans isomerization of azo dyes XC₆H₄N=NC₆H₄N(C₂H₅)₂ (where X is H, OCH₃, CN, and NO₂) in poly(ethylene terephthalate) matrices, below the glass transition temperature, and in dibutylphthalate solutions has been studied kinetically in the temperature range 20–60°C. Kinetic behavior in the polymer is characterized by two or three simultaneous first-order processes with similar activation enthalpies. These processes reflect an unequal distribution of “tie-molecules,” “folds,” and “cilia” in the amorphous region of the polymer. Lightfastness of the dyes in poly(ethylene terephthalate) films has been investigated. Polymer morphology strongly affected the photofading, but no significant influence was observed in the kinetic experiments.     

Cell-free protein synthesis through solubilisate exchange in water/oil emulsion compartments

This work is aimed at finding conditions under which synthetic compartments used as cell models can fuse with each other and allow reagents contained in the different compartments to react. This goal seems to be best achieved by the use of water in oil emulsions (w/o) with dimensions in the range of 30-60 microm. In particular, cell-free EGFP (enhanced green fluorescent protein) synthesis takes place in Tween 80/Span 80 w/o emulsions, and the extent of the reaction can be monitored directly by fluorescence. The medium is mineral oil, containing 0.5 % v/v aqueous solution. Different premixing configurations of the components (plasmid, amino acids, E. Coli extract) are used and compared. The in vitro synthesis of EGFP in emulsion droplets proceeds for 1 h, and the yield is 7.5 ng microL(-1) protein. EGFP synthesis in aqueous solution takes place for at least 5 h. The yield is 10.5 ng microL(-1) protein after 1 h and 15.8 ng microL(-1) protein after 5 h. The results with the w/o emulsions show that solubilisate exchange takes place among the different water droplets, but it is not possible to demonstrate clearly that a true fusion takes place.     

Control and Virtual Reality Simulation of Tendon Driven Mechanisms

In this paper the authors present a control strategy for tendon driven mechanisms. The aim of the control system is to find the correct torques which the motors have to exert to make the end effector describe a specific trajectory. In robotic assemblies this problem is often solved with closed loop algorithm, but here a simpler method, based on a open loop strategy, is developed. The difficulties in the actuation are in keeping the belt tight during all working conditions. So an innovative solution of this problem is presented here. This methodology can be easily applied in real time monitoring or very fast operations. For this reason several virtual reality simulations, developed using codes written in Virtual Reality Markup Language, are also presented. This approach is very efficient because it requires a very low cpu computation time, small size files, and the manipulator can be easily put into different simulated scenarios.     

Analisys of Electric Arc Furnace Slag

The black slag produced during the melting process in electric arc furnace can be used as adjunct in the operation of land filling, building operation of road grounds, and production of concrete. Their use limitation is due to the presence of polluting chemical elements, including Cr, Ba, V, Mo, etc, that can be dangerous for human and environment, resulting by using of polluted scraps (i.e., painted, lubricated, or polymeric compound scraps). The release extent of polluting elements appears to behave as a function of the constituent phases, i.e., CaO, SiO₂, Al₂O₃, MgO, etc. The main tools employed in the characterization of the black slag consists in optical basicity calculation, SEM‐EBS and SEM‐EDS analysis. The combination of the data coming from chemical analysis, micro‐structural examination and releasing tests allows to identify the correct chemical range avoiding dangerous chemical release and to develop a working disposal procedure for the investigated slag.