Skin diseases associated with chronic hepatitis C

The authors are discussing hepatic and extrahepatic pathologic processes caused by hepatitis C virus (HCV) infection and they focus their interest to the skin disorders appearing in the presence of chronic, active HCV infections. The trigger of the immunologic processes leading to dermatologic manifestations are the activated T cells (CD8 + cytotoxic T lymphocytes), cytokins, and also the expansion of certain B cells. Pathologic immunologic phenomena may initiate various dermatologic manifestations. Immunoglobulins, immuncomplexes generated by the disease itself are manifested as various forms of cutan vasculitis. In the present series of patients (pts), HCV related skin disorders known from the literature were diagnosed in eleven cases and they were representing 7 different disease entities. These were palpable purpura (3 pts), urticaria, prurigo and alopecia areata (2-2 pts), lichen ruber planus, pruritus and vitiligo (1-1 patient respectively). The case reports of 2 pts, one with palpable purpura (vasculitis purpurica), one with prurigo and vitiligo are presented in details.     

Axial nonuniformities and flow in columns for capillary electrochromatography

Unlike in capillary zone electrophoresis and microscale high-performance liquid chromatography, columns in capillary electrochromatography (CEC) have discontinuities of the electric field strength and the flow velocity at the interface of the packed and open segments of the column. The goal of the present work is to offer a framework for measuring and interpreting the relevant electrochromatographic parameters such as the electric field strength, the potential drop, and the flow velocity in the packed segment of a CEC column. This would help us gain further insight in the electrochromatographic process and facilitate the design of CEC separation technology and comparison of data from different sources. First, the flow of ions that is governed by the conservation of current is analyzed and the potential drop across the packed and open segments of the column calculated. Then, conservation of volumetric flow rate is used to calculate the flow velocities through the two segments and, further, to estimate the net flow velocity through such a column. To satisfy the mass conservation law, in most cases a "flow-equalizing intersegmental pressure", which is different from the pressures at the two ends of the column, develops at the interface of the packed and the open segments. The intersegmental pressure, induced to equalize the flow rates in the two segments, has been shown to have a significant effect on the magnitude as well as the radial distribution of the flow velocity in the open segment, where the net flow becomes a mixture of electroosmotic and pressure-driven flows.     

Multiple nitric oxide sources in neurogenic plasma extravasation in rat hindpaw skin

The contribution of nitric oxide (NO) to capsaicin-evoked plasma extravasation was studied in rat hindpaw skin. Two inhibitors of NO synthase were used: 7-nitroindazole, with a selectivity for nerve-derived NO, and the L-arginine derivative, N(omega)-nitro-L-arginine (L-NOARG), which is a non-selective inhibitor. Plasma extravasation was induced by intraplantar injection of 5 microg/50 microl capsaicin and measured by the Evans blue leakage technique. Both acute and chronic administration of 7-nitroindazole significantly reduced capsaicin-evoked plasma extravasation in rat hind-paw skin, whereas L-NOARG enhanced it. This enhancement was abolished non-stereospecifically by either L- or D-arginine. Our results suggest that NO production from different sources yields a complex action in maintaining the endothelial integrity in neurogenic plasma extravasation.     

Information schema constructs for defining warehouse databases of genotypes and phenotypes of system manifestation features

Our long-term objective is to develop a software toolbox for pre-embodiment design of complex and heterogeneous systems, such as cyber-physical systems. The novelty of this toolbox is that it uses system manifestation features (SMFs) for transdisciplinary modeling of these systems. The main challenges of implementation of the toolbox are functional design- and language-independent computational realization of the warehouses, and systematic development and management of the various evolving implements of SMFs (genotypes, phenotypes, and instances). Therefore, an information schema construct (ISC) based approach is proposed to create the schemata of the associated warehouse databases and the above-mentioned SMF implements. ISCs logically arrange the data contents of SMFs in a set of relational tables of varying semantics. In this article we present the ISCs necessary for creation of genotypes and phenotypes. They increase the efficiency of the database development process and make the data relationships transparent. Our follow-up research focuses on the elaboration of the SMF instances based system modeling methodology.     

Probabilistic frequent subtrees for efficient graph classification and retrieval

Frequent subgraphs proved to be powerful features for graph classification and prediction tasks. Their practical use is, however, limited by the computational intractability of pattern enumeration and that of graph embedding into frequent subgraph feature spaces. We propose a simple probabilistic technique that resolves both limitations. In particular, we restrict the pattern language to trees and relax the demand on the completeness of the mining algorithm, as well as on the correctness of the pattern matching operator by replacing transaction and query graphs with small random samples of their spanning trees. In this way we consider only a random subset of frequent subtrees, called probabilistic frequent subtrees, that can be enumerated efficiently. Our extensive empirical evaluation on artificial and benchmark molecular graph datasets shows that probabilistic frequent subtrees can be listed in practically feasible time and that their predictive and retrieval performance is very close even to those of complete sets of frequent subgraphs. We also present different fast techniques for computing the embedding of unseen graphs into (probabilistic frequent) subtree feature spaces. These algorithms utilize the partial order on tree patterns induced by subgraph isomorphism and, as we show empirically, require much less evaluations of subtree isomorphism than the standard brute-force algorithm. We also consider partial embeddings, i.e., when only a part of the feature vector has to be calculated. In particular, we propose a highly effective practical algorithm that significantly reduces the number of pattern matching evaluations required by the classical min-hashing algorithm approximating Jaccard-similarities.     

Fetal phonocardiography--past and future possibilities

The paper presents an overview of the 15 year long development of fetal phonocardiography including the works on the applied signal processing methods for identification of sound components. Based on the improvements achieved on this field, the paper shows that beyond the traditional CTG test the phonocardiography may be successfully applied for long-term fetal measurements and home monitoring. In addition, by indication of heart murmurs based on a comprehensive analysis of the recorded heart sound congenital heart defects can also be detected together with additional features in the third trimester. This makes an early widespread screening possible combined with the prescribed CTG test even at home using a telemedicine system.     

Formal validation of domain-specific languages with derived features and well-formedness constraints

Despite the wide range of existing tool support, constructing a design environment for a complex domain-specific language (DSL) is still a tedious task as the large number of derived features and well-formedness constraints complementing the domain metamodel necessitate special handling. Such derived features and constraints are frequently defined by declarative techniques (such graph patterns or OCL invariants). However, for complex domains, derived features and constraints can easily be formalized incorrectly resulting in inconsistent, incomplete or ambiguous DSL specifications. To detect such issues, we propose an automated mapping of EMF metamodels enriched with derived features and well-formedness constraints captured as graph queries in EMF-IncQuery or (a subset of) OCL invariants into an effectively propositional fragment of first-order logic which can be efficiently analyzed by back-end reasoners. On the conceptual level, the main added value of our encoding is (1) to transform graph patterns of the EMF-IncQuery framework into FOL and (2) to introduce approximations for complex language features (e.g., transitive closure or multiplicities) which are not expressible in FOL. On the practical level, we identify and address relevant challenges and scenarios for systematically validating DSL specifications. Our approach is supported by a tool, and it will be illustrated on analyzing a DSL in the avionics domain. We also present initial performance experiments for the validation using Z3 and Alloy as back-end reasoners.     

Imaging polarimetry of the fogbow: polarization characteristics of white rainbows measured in the high Arctic

The knowledge on the optics of fogbows is scarce, and their polarization characteristics have never been measured to our knowledge. To fill this gap we measured the polarization features of 16 fogbows during the Beringia 2005 Arctic polar research expedition by imaging polarimetry in the red, green and blue spectral ranges. We present here the first polarization patterns of the fogbow. In the patterns of the degree of linear polarization p, fogbows and their supernumerary bows are best visible in the red spectral range due to the least dilution of fogbow light by light scattered in air. In the patterns of the angle of polarization α fogbows are practically not discernible because their α-pattern is the same as that of the sky: the direction of polarization is perpendicular to the plane of scattering and is parallel to the arc of the bow, independently of the wavelength. Fogbows and their supernumeraries were best seen in the patterns of the polarized radiance. In these patterns the angular distance δ between the peaks of the primary and the first supernumerary and the angular width σ of the primary bow were determined along different radii from the center of the bow. δ ranged between 6.08° and 13.41°, while σ changed from 5.25° to 19.47°. Certain fogbows were relatively homogeneous, meaning small variations of δ and σ along their bows. Other fogbows were heterogeneous, possessing quite variable δ- and σ-values along their bows. This variability could be a consequence of the characteristics of the high Arctic with open waters within the ice shield resulting in the spatiotemporal change of the droplet size within the fog.     

Capillary electrochromatography of proteins on an anion-exchanger column

Capillary electrochromatography (CEC) of proteins was carried out using 50-microm-i.d. fused-silica capillaries packed with 5-microm silica beads having strong anion-exchanger functions attached to hydrophilic spacers at the chromatographic surface. The siliceous microspheres and the capillary innerwall were treated first with a heterobifunctional silanizing agent and reacted subsequently with a vinyl monomer containing quaternary ammonium groups to form a "tentacular" anion exchanger. A mixture of bovine carbonic anhydrase, alpha-lactalbumin, soybean trypsin inhibitor, and ovalbumin was separated using CEC by isocratic elution in the codirectional mode with aqueous phosphate buffer, pH 7.0, containing sodium chloride. The retention mechanism of isocratic CEC for proteins on the anion-exchanger column was illustrated by the results of a study on the effect of salt concentration on the separation. The potential of CEC for protein separation with high resolution was also demonstrated by electrochromatograms of conalbumin and hemoglobin variants. The results shed light on the mechanism of protein separation by isocratic CEC, which is believed to be a combination of chromatographic retention by electrostatic interactions and electrophoretic migration. Assuming that the contributions of the two mechanisms to the overall migration velocity are additive, an electrochromatographic resolution equation was derived and compared to the resolution equation in HPLC to reveal the constituents responsible for the enhancement of resolution by CEC with respect to that in HPLC. The advantage of CEC was also examined by comparing peak capacities in CEC on an, isocratic platform with peak capacities obtained with isocratic and gradient elution HPLC.     

A review of reliable numerical models for three‐dimensional linear parabolic problems

The preservation of characteristic qualitative properties of different phenomena is a more and more important requirement in the construction of reliable numerical models. For phenomena that can be mathematically described by linear partial differential equations of parabolic type (such as the heat conduction, the diffusion, the pricing of options, etc.), the most important qualitative properties are: the maximum–minimum principle, the non‐negativity preservation and the maximum norm contractivity. In this paper, we analyse the discrete analogues of the above properties for finite difference and finite element models, and we give a systematic overview of conditions that guarantee the required properties a priori. We have chosen the heat conduction process to illustrate the main concepts, but engineers and scientists involved in scientific computing can easily reformulate the results for other problems too. Copyright © 2006 John Wiley & Sons, Ltd.