Real-time guidewire simulation in complex vascular models

The base of all training in interventional radiology aims at the development of the core skills in manipulating the instruments. Computer simulators are emerging to help in this task. This paper extends our previous framework with more realistic instrument behaviour and more complex vascular models. The instrument is modelled as a hybrid mass–spring particle system while the vasculature is a triangulated surface mesh segmented from patient data sets. A specially designed commercial haptic device allows the trainee to use real instruments to guide the simulation through the vasculature selected from a database of 23 different patients. A new collision detection algorithm allows an efficient computation of the contacts, therefore leaving more time to deal with the collision response for a realistic simulation in real time. The behaviour of our simulated instruments has been visually compared with the real ones and assessed by experienced interventional radiologists. Preliminary results show close correlations and a realistic behaviour.

Adaptive Synthesis of Functional Amphiphilic Dendrons as a Novel Approach to Artificial Supramolecular Objects

Supramolecular structures, such as micelles, liposomes, polymerosomes or dendrimerosomes, are widely studied and used as drug delivery systems. The behavior of amphiphilic building blocks strongly depends on their spatial distribution and shape of polar and nonpolar component. This report is focused on the development of new versatile synthetic protocols for amphiphilic carbosilane dendrons (amp-CS-DDNs) capable of self-assembly to regular micelles and other supramolecular objects. The presented strategy enables the fine modification of amphiphilic structure in several ways and also enables the facile connection of a desired functionality. DLS experiments demonstrated correlations between structural parameters of amp-CS-DDNs and the size of formed nanoparticles. For detailed information about the organization and spatial distribution of amp-CS-DDNs assemblies, computer simulation models were studied by using molecular dynamics in explicit water.     

Cytochrome c Catalyzes the Hydrogen Peroxide‐Assisted Oxidative Desulfuration of 2‐Thiouridines in Transfer RNAs

The 5‐substituted 2‐thiouridines (R5S2Us) present in the first (wobble) position of the anticodon of transfer RNAs (tRNAs) contribute to accuracy in reading mRNA codons and tuning protein synthesis. Previously, we showed that, under oxidative stress conditions in vitro, R5S2Us were sensitive to hydrogen peroxide (H₂O₂) and that their oxidative desulfuration produced 5‐substituted uridines (R5Us) and 4‐pyrimidinone nucleosides (R5H2Us) at a ratio that depended on the pH and an R5 substituent. Here, we demonstrate that the desulfuration of 2‐thiouridines, either alone or within an RNA/tRNA chain, is catalyzed by cytochrome c (cyt c). Its kinetics are similar to those of Fenton‐type catalytic 2‐thiouridine (S2U) desulfuration. Cyt c/H₂O₂‐ and Fe^II‐mediated reactions deliver predominantly 4‐pyrimidinone nucleoside (H2U)‐type products. The pathway of the cyt c/H₂O₂‐peroxidase‐mediated S2U→H2U transformation through uridine sulfenic (U‐SOH), sulfinic (U‐SO₂H), and sulfonic (U‐SO₃H) intermediates is confirmed by LC–MS. The cyt c/H₂O₂‐mediated oxidative damage of S2U‐tRNA may have biological relevance through alteration of the cellular functions of transfer RNA.     

Effect of patient age and gender on clinical decisions.

Examined the effect of patient age and gender on clinical decisions of 209 licensed clinical psychologists. Ss read vignettes describing a patient with symptoms of depression. Age and gender of the patient were varied in a between-Ss design. Ss made decisions regarding the diagnosis, treatment mode, treatment setting, and prognosis. Ss were also asked to list information that was influential in their decision regarding treatment setting. Age had a significant effect on diagnostic and treatment decisions, whereas the sex of the patient affected only diagnostic decision. As predicted, the age and sex of the patient had an impact on the information clinicians focused on in making their decisions. Discussion focuses on the theoretical rationale and implications of these findings. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concept Formation During Interactive Theory Revision

This article examines the problem of concept formation in machine learning, and focuses in particular on the problem of aggregation, i .e., the decision of which objects are to be grouped together into a new concept. While existing concept formation approaches have mainly concentrated on aggregation constraints that rely on structural or correlational properties of the concepts themselves, we argue that in an integrated learning system, other learning activities can provide an additional context that focuses concept formation before structural criteria are applied. In particular, we present the concept formation method realized by the KRT and CLT components of the integrated learning system MOBAL. In MOBAL, a concept formation attempt is triggered whenever no existing concept can adequately capture the rule instance and exception sets as they arise from the theory revision activities of the system. We describe how the so-proposed aggregate is characterized by a set of (function-free) first-order Horn clauses and how these are evaluated according to structural criteria to decide about the introduction of the concept into the representation. We show how a structural criterion can be used to ensure that any new concept improves the structure of the knowledge base, and we empirically evaluate how the introduction of new concepts according to different criteria affects the classification accuracy of learned rules.     

Tuning and implementation variants of discrete-time ADRC

Practical implementations of active disturbance rejection control (ADRC) will almost always take place in discretized form. Since applications may have quite different needs regarding their discrete-time controllers, this article summarizes and extends the available set of ADRC implementations to provide a suitable variant for as many as possible use cases. In doing so, the gap between quasi-continuous and discrete-time controller tuning is closed for applications with low sampling frequencies. The main contribution of this article is the derivation of three different discrete-time implementations of error-based ADRC. It is shown that these are almost one-to-one counterparts of existing output-based implementations, to the point where transfer functions and coefficients can be reused in unaltered form. In this way, error-based implementations become firmly rooted in the established landscape of discrete-time ADRC. Furthermore, it becomes possible to equip error-based variants with windup protection abilities known from output-based ADRC.     

Attribute-oriented fuzzy generalization in proximity- and similarity-based relational database systems

In this article we investigate an attribute-oriented induction approach for acquisition of abstract knowledge from data stored in a fuzzy database environment. We utilize a proximity-based fuzzy database schema as the medium carrying the original information, where lack of precise information about an entity can be reflected via multiple attribute values, and the classical equivalence relation is replaced with the broader fuzzy proximity relation. We analyze in detail the process of attribute-oriented induction by concept hierarchies, utilizing the original properties of fuzzy databases to support this established data mining technique. In our approach we take full advantage of the implicit knowledge about the similarity of original attribute values, included by default in the investigated fuzzy database schemas. © 2007 Wiley Periodicals, Inc. Int J Int Syst 22: 763–779, 2007.     

Optimization of a Multipolar Permanent-Magnet Rotor Comprising Two Arc Segments per Pole

This paper investigates the optimal design of a brushless machine with an internal rotor comprising a permanent magnet (PM) array that is made up from discrete anisotropic arc segments. The particular case where the magnet array is constructed from two arc segments per pole is considered, where the magnets are alternately magnetized normally and tangentially to the rotor surface. The influence of the relative magnetic airgap and magnet thickness on the optimal PM array arrangement is analyzed, and it is shown that the optimal arrangement is largely independent of the airgap width. Both analytical and numerical approaches to the optimization problem are presented, the latter using a 2-D parametric finite-element model.     

Dual boundary element method for axisymmetric crack analysis

In this paper a dual boundary element formulation is developed and applied to the evaluation of stress intensity factors in, and propagation of, axisymmetric cracks. The displacement and stress boundary integral equations are reviewed and the asymptotic behaviour of their singular and hypersingular kernels is discussed. The modified crack closure integral method is employed to evaluate the stress intensity factors. The combination of the dual formulation with this method requires the adoption of an interpolating function for stresses after the crack tip. Different functions are tested under a conservative criterion for the evaluation of the stress intensity factors. A crack propagation procedure is implemented using the maximum principal stress direction rule. The robustness of the technique is assessed through several examples where results are compared either to analytical ones or to BEM and FEM formulations.     

A central fission pathway in alkylphenol ethoxylate biodegradation

A representative alkylphenol Triton X-100 (having 9.5 oxyethylene subunits) was treated over 40 days under the conditions of the continuous flow activated sludge simulation test in a plant with aeration and denitrification chambers. Treated sewage was separated by sequential extraction with ethyl acetate and chloroform. The extracts were analysed by high-performance liquid chromatography-electrospray ionisation-mass spectrometry (HPLC-ESI-MS). Single ion chromatograms of the chloroform extracts showed the presence of neutral, mono- and di-carboxylated poly(ethylene glycols). This is evidence of the central fission of alkylphenol ethoxylates (APE). Simultaneously, the APE having omega-carboxylated oxyethylene chains were identified. This is the evidence that apart from central fission, the omega-oxidation oxyethylene chain pathway also occurs.