Basic Variants Research Articles

Cytotoxicity of RNases is increased by cationization and counteracted by K Ca channels

K Ca channels are involved in control of cell proliferation and differentiation. Here we have revealed their role in overcoming the RNase-induced cytotoxicity. Toxic effects of Streptomyces aureofaciens RNases Sa, Sa2, Sa3, and of RNase Sa charge reversal mutants on the human embryonic kidney cell lines differing only by the presence of K Ca channels were characterized. In contrast to other RNases, a basic variant of RNase Sa and RNase Sa3 exhibit significant cytotoxic activity of the same order of magnitude as onconase. Our data indicate the absence of a correlation between catalytic activity and stability of RNases and cytotoxicity. On the other hand, cationization enhances toxic effect of an RNase indicating the major role of a positive charge. Essentially lower sensitivity to cytotoxic microbial RNases of cells expressing K Ca channels was found. These results suggest that cells without the K Ca channel activity cannot counteract toxic effect of RNases.

Simplified non-linear seismic analysis of infilled reinforced concrete frames

The N2 method for simplified non-linear seismic analysis has been extended in order to make it applicable to infilled reinforced concrete frames. Compared to the simple basic variant of the N2 method, two important differences apply. A multi-linear idealization of the pushover curve, which takes into account the strength degradation which occurs after the infill fails, has to be made, and specific reduction factors, developed in a companion paper, have to be used for the determination of inelastic spectra. It is shown that the N2 method can also be used for the determination of approximate summarized IDA curves. The proposed method was applied to two test buildings. The results were compared with the results obtained by non-linear dynamic analyses for three sets of ground motions, and a reasonable accuracy was demonstrated. A similar extension of the N2 method can be made to any structural system, provided that an appropriate specific R–µ–T relation is available. Copyright © 2004 John Wiley & Sons, Ltd.

Regieren durch Solidarität?

References to solidarity are all but omnipresent. This high regard for solidarity is closely related to the important role which solidarity plays as a resource of the welfare state and its inclusive policies. Social insurance and the trade unions as components of the political system stood in the foreground for over a century. In an age in which globalisation intensifies the problems of stability in the welfare state, this organised solidarity also begins to falter. At the same time more basic variants of solidarity are gaining importance. The small networks of daily life, which are distant from functional systems, are increasingly coming within the range of perception of the »new welfare state« and could be planned and consumed as elements of reorganising strategies – with once again new problems appearing on the horizon.

Topologies of three-phase rectifiers with near sinusoidal input currents

Several topologies of three-phase low-harmonic diode rectifiers equipped with inductors, capacitors and diodes, based on an original solution, are presented. Inductors and capacitors are used in conjunction with the three-phase diode rectifier bridge to improve the waveform of the currents drawn from the utility grid. For the basic variant of the three-phase rectifier, representative characteristics and design elements are presented. Starting from this configuration, an AC/DC converter with small holding current and a four-quadrant frequency converter are proposed. The operation of the proposed converters is analysed and, on this basis, design considerations are reviewed. Several possible applications of the converter variants are mentioned. Analytically obtained results have bee experimentally verified.

A Comparative Functional Analysis of Plasma Membrane Ca2+ Pump Isoforms in Intact Cells

The four basic isoforms of the plasma membrane Ca2+ pump and the two C-terminally truncated spliced variants PMCA4CII(4a) and 3CII(3a) were transiently overexpressed in Chinese hamster ovary cells together with aequorin targeted to the cytosol, the endoplasmic reticulum, and the mitochondria. As PMCA3CII(3a) had not yet been cloned and studied, it was cloned for this study, partially purified, and characterized. At variance with the corresponding truncated variant of PMCA4, which had been studied previously, PMCA3CII(3a) had very high calmodulin affinity. All four basic pump variants influenced the homeostasis of Ca2+ in the native intracellular environment. The level of [Ca2+] in the endoplasmic reticulum and the height of the [Ca2+] transients generated in the cytosol and in the mitochondria by the emptying of the endoplasmic reticulum store by inositol 1,4,5-trisphosphate were all reduced by the overexpression of the pumps. The effects were much greater with the neuron-specific PMCA2 and PMCA3 than with the ubiquitously expressed isoforms 1 and 4. Unexpectedly, the truncated PMCA3 and PMCA4 were as effective as the full-length variants in influencing the homeostasis of Ca2+ in the cytosol and the organelles. In particular, PMCA4CII(4a) was as effective as PMCA4CI(4b), even if its affinity for calmodulin is much lower. The results indicate that the availability of calmodulin may not be critical for the modulation of PMCA pumps in vivo.

Neutronic features of the GT-MHR reactor

The design of a Gas Turbine–Modular Helium Reactor (GT-MHR) of 600 MWt power is being developed in frames of “The Agreement between the Government of the United States of America and the Government of the Russian Federation on Scientific and Technical Cooperation in the Management of Plutonium That Has Been Withdrawn from Nuclear Military Programs” signed on July 24, 1998. The reactor concept is based on the deep burnup of initially loaded plutonium fuel at its single use in core and the subsequent disposal of the spent fuel without additional processing. The present paper describes the analysis of the basic features of the GT-MHR reactor core fueled by plutonium: 1. The annular type core design is used to decrease fuel temperature in accidents without active heat removal. 2. Unlike other alternatives for plutonium disposition (MOX fuel), in the basic variant of GT-MHR reactor design no fertile materials such as U-238, or Th-232 are used. Erbium is used as a burnable poison and means for ensuring the negative reactivity temperature coefficient. 3. Deep fuel burnup (640 MW day/kg on the average) leads to the significant accumulation of Pu-241 during irradiation of weapons grade Pu fuel. This fact determines the specific time dependence of the multiplication factor in the end of the fuel lifetime. 4. Rather hard neutron spectrum in the annular-type active core, and the essentially thermal spectrum in the reflectors cause a peak in the power distribution near the core-reflector boundary. Fuel and burnable poison zoning are used to control power profile. 5. The movement of control rods located in the side reflector noticeably deforms the power distribution in the core. 6. The temperature coefficient of reactivity depends both on the temperature and burnup level. In the GT-MHR reactor with plutonium fuel the temperature reactivity coefficient has values close to zero for temperatures less than 400 °C at the end of the partial fuel cycle. 7. Deep fuel burnup, achievable through the use of fuel particles with multilayer coatings, and high efficiency of transforming the thermal energy into electricity allow the effective utilization of plutonium in the GT-MHR reactor.

Charge–Charge Interactions are Key Determinants of the p K Values of Ionizable Groups in Ribonuclease Sa (pI=3.5) and a Basic Variant (pI=10.2)

The p K values of the titratable groups in ribonuclease Sa (RNase Sa) (pI=3.5), and a charge-reversed variant with five carboxyl to lysine substitutions, 5K RNase Sa (pI=10.2), have been determined by NMR at 20 °C in 0.1 M NaCl. In RNase Sa, 18 p K values and in 5K, 11 p K values were measured. The carboxyl group of Asp33, which is buried and forms three intramolecular hydrogen bonds in RNase Sa, has the lowest p K (2.4), whereas Asp79, which is also buried but does not form hydrogen bonds, has the most elevated p K (7.4). These results highlight the importance of desolvation and charge–dipole interactions in perturbing p K values of buried groups. Alkaline titration revealed that the terminal amine of RNase Sa and all eight tyrosine residues have significantly increased p K values relative to model compounds. A primary objective in this study was to investigate the influence of charge–charge interactions on the p K values by comparing results from RNase Sa with those from the 5K variant. The solution structures of the two proteins are very similar as revealed by NMR and other spectroscopic data, with only small changes at the N terminus and in the α-helix. Consequently, the ionizable groups will have similar environments in the two variants and desolvation and charge–dipole interactions will have comparable effects on the p K values of both. Their p K differences, therefore, are expected to be chiefly due to the different charge–charge interactions. As anticipated from its higher net charge, all measured p K values in 5K RNase are lowered relative to wild-type RNase Sa, with the largest decrease being 2.2 pH units for Glu14. The p K differences (p K Sa−p K 5K) calculated using a simple model based on Coulomb's Law and a dielectric constant of 45 agree well with the experimental values. This demonstrates that the p K differences between wild-type and 5K RNase Sa are mainly due to changes in the electrostatic interactions between the ionizable groups. p K values calculated using Coulomb's Law also showed a good correlation ( R=0.83) with experimental values. The more complex model based on a finite-difference solution to the Poisson–Boltzmann equation, which considers desolvation and charge–dipole interactions in addition to charge–charge interactions, was also used to calculate p K values. Surprisingly, these values are more poorly correlated ( R=0.65) with the values from experiment. Taken together, the results are evidence that charge–charge interactions are the chief perturbant of the p K values of ionizable groups on the protein surface, which is where the majority of the ionizable groups are positioned in proteins.

Cascade Electronuclear Systems with a Liquid-Cadmium Rectifier

Three basic variants of bireactor electronuclear systems are discussed. It is shown that the most effective, from the standpoint of the best output characteristics and safe operating regimes, are bireactor systems with a booster operating on enriched uranium and a liquid-cadmium rectifier. Monte Carlo simulation is used to show that during operation of the setup conditions can be created under which the destruction of an intermediate layer makes such systems supercritical (keff > 1). This can be avoided using a special construction of the rectifier with liquid cadmium. Cascade nuclear systems possess substantial advantages over other nuclear setups (critical reactors, single-reactor electronuclear systems), making it possible to decrease the proton current by approximately a factor of 10 and ensure in the process the required power level and neutron flux, and the presence of a fast and thermal cores makes it possible to burn efficiently not only transuranium elements but also to transmute fission products – cesium, iodine, technetium, which have a high capacity for penetrating into the biosphere.

Effect of increasing selenite concentrations, vitamin E supplementation and different fetal calf serum content on GPx1 activity in primary cultured rabbit hepatocytes

Primary rabbit hepatocytes from 6 week old female New Zealand White rabbits (3.0 × 10 6 viable hepatocytes per treatment) were incubated for 24 h or 48 h with two basic variants of the selenium and vitamin E free DMEM/F12-HAM nutrition medium containing 2.5% or 10% fetal calf serum (FCS). Selenium and vitamin E concentrations of the media were varied by the addition of 0, 10, 50 and 100 ng Se/mL medium as sodium selenite and 100 μg α-tocopheryl acetate/mL. Lactic dehydrogenase (LDH) leakage of the hepatocytes was not influenced by the various selenium concentrations of the media, whereas vitamin E addition significantly inhibited LDH release. The activity of cellular glutathione peroxidase (GPx1) was markedly induced by increasing the selenium supplementation of the culture media. Vitamin E supply further enhanced GPx1 induction. In hepatocytes cultivated at the lower serum concentration (2.5% FCS), increasing the selenite concentration of the media raised GPx1 and reduced the intracellular levels of the reduced tripeptide glutathione (GSH). No vectored relation between the selenium concentration of the media and the activity of superoxide dismutase (SOD) could be observed. After both incubation periods (24 h and 48 h) SOD activity was significantly higher in the cytosol of hepatocytes grown in media containing 10% FCS as compared to cells incubated at the 2.5% FCS level. Furthermore, SOD activity was reduced by the addition of vitamin E to the media. In conclusion the results indicate an effective metabolism of rabbit hepatocytes for selenite even in amounts as low as nanograms. A general cytoprotective role for vitamin E can be shown by its ability to decrease LDH leakage and by the reduction of SOD activity.

Launch vehicles for low-cost planetary missions

Delta has been synonymous with the launch of planetary missions for several decades. To make launches of all missions, including planetary missions, more affordable, launch vehicle evolution is necessary. The history of the Delta expendable launch vehicle has been one of constant evolution for almost 40 years and continues to evolve. Delta expendable launch vehicles include three basic variants: Delta II, Delta III, and Delta IV. Each vehicle is described and performance capabilities given for escape missions, GTO missions, and LEO missions. Injection accuracy for the Delta II has been better than 3 sigma. Actual injection accuracy performance figures for several planetary missions are presented. Data on launch environments are presented as well as the cleanliness environment available in the fairing and mobile service tower. Since many planetary missions depend on rather restricted launch windows, data are presented showing Delta's launch record within the launch window requirements. Delta has launched approximately 30 secondary missions over the past several years. Boeing is developing dual-payload capabilities for Delta II, Delta III, and Delta IV Heavy. Boeing also is evaluating auxiliary launch concepts for Delta IV. Over the past 40 years, Delta has significantly increased overall capability while reducing launch costs. Delta IV will continue this tradition with dramatic cost reductions while providing a more robust expendable launch vehicle.

Adaptive business intelligence based on evolution strategies: some application examples of self-adaptive software

Self-adaptive software is one of the key discoveries in the field of evolutionary computation, originally invented in the framework of so-called Evolution Strategies in Germany. Self-adaptivity enables the algorithm to dynamically adapt to the problem characteristics and even to cope with changing environmental conditions – as they occur in unforeseeable ways in many real-world business applications. In evolution strategies, self-adaptability is generated by means of an evolutionary search process that operates on the solutions generated by the method as well as on the evolution strategy’s parameters, i.e., the algorithm itself. By focusing on a basic algorithmic variant of evolution strategies, the fundamental idea of self-adaptation is outlined in this paper. Applications of evolution strategies for NuTech’s clients include the whole range of business tasks, including R&D, technical design, control, production, quality control, logistics, and management decision support. While such examples can of course not be disclosed, we illustrate the capabilities of evolution strategies by giving some simpler application examples to problems occurring in traffic control and engineering.

Polyhedral results for the edge capacity polytope

Network loading problems occur in the design of telecommunication networks, in many different settings. For instance, bifurcated or non-bifurcated routing (also called splittable and unsplittable) can be considered. In most settings, the same polyhedral structures return. A better understanding of these structures therefore can have a major impact on the tractability of polyhedral-guided solution methods. In this paper, we investigate the polytopes of the problem restricted to one arc/edge of the network (the undirected/directed edge capacity problem) for the non-bifurcated routing case. As an example, one of the basic variants of network loading is described, including an integer linear programming formulation. As the edge capacity problems are relaxations of this network loading problem, their polytopes are intimately related. We give conditions under which the inequalities of the edge capacity polytopes define facets of the network loading polytope. We describe classes of strong valid inequalities for the edge capacity polytopes, and we derive conditions under which these constraints define facets. For the diverse classes the complexity of lifting projected variables is stated. The derived inequalities are tested on (i) the edge capacity problem itself and (ii) the described variant of the network loading problem. The results show that the inequalities substantially reduce the number of nodes needed in a branch-and-cut approach. Moreover, they show the importance of the edge subproblem for solving network loading problems.

Synthesis of Arabic from short sound clusters

This article describes an unrestricted vocabulary text-to-speech (TTS) conversion system for the synthesis of Standard Arabic (SA) speech. The system uses short phonetic clusters that are derived from the Arabic syllables to synthesize Arabic. Basic and phonetic variants of the synthesis units are defined after qualitative and quantitative analyses of the phonetics of SA. A speech database of the synthesis units and their phonetic variations is created and the units are tested to control their segmental quality. Besides the types of synthesis unit used, their enhancement with phonetic variants, and their segmental quality control, the production of good quality speech also depends on waveform analysis and the method used to concatenate the synthesis units together. Waveform analysis is needed to condition the selected synthesis units at their junctures to produce synthesized speech of better quality. The types of speech juncture between contiguous units, the phonetic characteristics of the sounds surrounding the junctures and the concatenation artifacts occurring across the junctures are important and will be discussed. The results of waveform analysis and smoothing algorithms will be presented. The intelligibility of synthesized Arabic by a standard intelligibility test method that is adapted to suit the Arabic phonetic characteristics and scoring the results of the tests will also be dealt with.

Comparative investigations of gluten proteins from different wheat species

Flours of different wheat species (common wheats including winter wheat, spring wheat, and wheat rye hybrid, spelt, durum wheat, emmer, and einkorn) were successively extracted with a salt solution and 60% (v/v) aqueous ethanol. The alcohol extracts (gliadins) were separated by reversed-phase HPLC. Six to nine different ω-gliadins were obtained for each wheat sample and were characterized by their relative amounts, the amino acid compositions, the N-terminal amino acid sequences, and the molecular masses. The wheats investigated showed typical differences in the qualitative and quantitative HPLC patterns. The amino acid compositions of all ω-type gliadins revealed significantly higher proportions of glutamine, proline, and phenylalanine compared with other gluten proteins. These three amino acids accounted for 70 to 86% of the total composition. Typical differences in amino acid compositions, N-terminal sequences, and molecular masses allowed a clear differentiation of the proteins into ω5- and ω1,2-type gliadins; the gliadin fractions of emmer and einkorn contained only the ω5-type, but not the ω1,2-type. ω5-Gliadins were characterized by extremely high proportions of glutamine (52–57 mol %) and relatively high proportions of proline (18–21 mol %) and phenylalanine (9–10 mol %). ω1,2-Gliadins had less glutamine (39–45 mol %) and phenylalanine (6–8 mol %), but much more proline (22–31 mol %). ω5-Gliadins of all wheats except emmer could be assigned to the N-terminal sequence variants SRQLSP or SRLLSP; the typical sequence of emmer ω5-gliadins was SMELQT. The N-terminal sequences of ω1,2-gliadins were characterized by two basic variants beginning with KELQSP or ARQLNP. The wheat rye hybrid had additionally components with the sequence RQLNPS known from ω-secalins of rye. The determination of molecular masses by MALDI-TOF mass spectrometry revealed a range of 44,000–55,000 for the ω5-type and a range of 36,000–44,000 for the ω1,2-type. Thus, the actual masses were by far lower than the values derived from SDS-PAGE mobility.

Dynamic experimentation on the confocal laser scanning microscope: application to soft‐solid, composite food materials

Confocal laser scanning microscopy (CLSM) is used to follow the dynamic structural evolution of several phase-separated mixed biopolymer gel composites. Two protein/polysaccharide mixed gel systems were examined: gelatin/maltodextrin and gelatin/agarose. These materials exhibit 'emulsion-like' structures, with included spherical particles of one phase (i.e. polymer A) within a continuous matrix of the second (i.e. polymer B). Compositional control of these materials allows the phase order to be inverted (i.e. polymer B included and polymer A continuous), giving four basic variants for the present composites. Tension and compression mechanical tests were conducted dynamically on the CLSM, with crack/microstructure interactions investigated using a notched compact tension geometry. Gelatin/maltodextrin composites exhibit a 'pseudo-yielding' stress/strain response in both tension and compression, when the gelatin-rich phase is continuous, which was attributed to debonding of the particle/matrix interface. This behaviour is significantly less apparent for both the gelatin/agarose composites, and the maltodextrin continuous gelatin/maltodextrin composites, with these materials responding in a nominally linear elastic manner. Values of the interfacial fracture energy for selected compositions of the two biopolymer systems were determined by 90 degrees peel testing, where a gelatin layer was peeled from either a maltodextrin or agarose substrate. For biopolymer layers 'cast' together, a value of 0.2 +/- 0.2 J m-2 was obtained for the fracture energy of a gelatin/maltodextrin interface, while a significantly higher value of 6.5 +/- 0.2 J m-2 was determined for a gelatin/agarose interface. The interfacial fracture energy of the two mixed systems was also determined following an indirect elastomer composite debonding model. An interfacial fracture energy of approximately 0.25 J m-2 was determined using this approach for the gelatin continuous gelatin/maltodextrin composite, which compares favourably with the value calculated directly by peel testing (i.e. approximately 0.2 J m-2). A somewhat higher value was estimated for the gelatin continuous gelatin/agarose system (1.0-2.0 J m-2), using this model, although there are severe limitations to this approach for this mixed gel system. In the present case, it is believed that the differing mechanical response of the two mixed biopolymer systems, when the gelatin phase is continuous, arises from the order of magnitude difference in interfacial fracture energy. It is postulated that polymer interdiffusion may occur across the interface for the gelatin/agarose system, to a significantly greater extent than for interfaces between gelatin and maltodextrin, resulting in a higher interfacial fracture energy.

Determination of the rational parameters for reinforcing elements of composite ribbed structures

Ribbed elements of thin walled structures with supports in the form of inhomogeneous ribs made of composite materials are studied. It is found that with a lower mass, reinforced panels can have higher rigidity characteristics compared to the basic three-layer variant. A strategy is introduced for determining the parameters of the reinforcements which is based on solving a system of nonlinear inequalities using a LPτ-search procedure within a chosen range of variation of the geometric and physical-mechanical characteristics of the structural materials. Results from a study using this method are described.

Constrained multi-object auctions and [formula omitted] -matching

Auctions become a most popular tool in various computational and e-commerce settings. Most auction theory deals either with auctions of a single object, or with multi-object setups where each good is sold by an independent auction. However, multi-object auctions might not satisfy such independence assumptions, either because the agents' valuations for the allocation of goods might be non-additive, or because there are (social) constraints on the set of possible allocations. In such cases the determination of an optimal allocation of the goods is a nontrivial computational problem. Some recent work in Operations Research (OR) and Artificial Intelligence (AI) have dealt with computational aspects of multi-object auctions, and relates to the non-additive nature of valuations. This paper deals with the complementary part, where there are simple constraints on the possible allocations of goods. We deal with the complexity of constrained multi-object auctions, and expose a connection of the related computational problem with the optimal b -matching problem. In particular, we show that a basic variant of the constrained multi-object auction is polynomially solvable. Then we deal with two natural extensions of this basic problem; we prove the NP-hardness of one of them, and use b -matching techniques for presenting a polynomial algorithm for the other.

New-generation space thermionic nuclear power systems with out-of-core electricity generating systems

The basic problems of the development of long service life thermionic nuclear power systems for space applications for supplying power to transport power modules, intended for placing spacecraft in a geostationary orbit using electrorocket motors and for providing prolonged operation of onboard systems for up to 10–15 years, are examined. Concepts for power systems with multi- and single-element thermionic low-temperature energy-conversion systems, which are placed outside the reactor core and in which heat is delivered to the emitters using molybdenum-lithium heat pipes at 1600–1670 K, are discussed as an example. Computational results are presented for the electro- and thermophysical characteristics of electricity generating systems and power systems with different variants of the design-technological solutions, including the possibility of increasing the service life by reserving a part of the thermionic electrical power. The mass/size characteristics of the power systems with basic variants of the systems are obtained and recommendations based on research and development work are made, 8 figures, 8 references.

COMPUTING WITH MEMBRANES (P SYSTEMS): A VARIANT

Membrane Computing is a recently introduced area of Molecular Computing, where a computation takes place in a membrane structure where multisets of objects evolve according to given rules (they can also pass through membranes). The obtained computing models were called P systems. In basic variants of P systems, the use of objects evolution rules is regulated by a given priority relation; moreover, each membrane has a label and one can send objects to precise membranes, identified by their labels. We propose here a variant where we get rid of both there rather artificial (non-biochemical) features. Instead, we add to membranes and to objects an "electrical charge" and the objects are passed through membranes according to their charge. We prove that such systems are able to characterize the one-letter recursively enumerable languages (equivalently, the recursively enumerable sets of natural numbers), providing that an extra feature is considered: the membranes can be made thicker or thinner (also dissolved) and the communication through a membrane is possible only when its thickness is equal to 1. Several open problems are formulated.

On Technomorphic Modelling and Classification of Biological Joints

Biological motion systems are of particular interest to engineers in robotics, prosthetics and micromechanics. Since biological motion systems show a high degree of mobility, smooth movements and minimal deployment of material, the analysis of such systems might help to invent or optimize technical motion systems. To enable the transfer of explanatory techniques, biomechanics and engineering need a shared terminology. Generally, a reference limb, muscles, tendons, a joint and a driven limb are forming two closed mechanisms with different transfer functions. The direction of the forces applied to links is influenced by guiding structures. Movable connections can be constructed by form closure, force closure, and compliance of an anisotropic segment between two rigid segments. Eleven different basic variants of rigid-body joint structures can be classified by the possible relative translatory and rotatory movements in orthogonal co-ordinates. If classified by the form of their rigid parts, biological rigid-body joints (diarthroses) show some similarities to technical joints, but occur in fewer basic variants. The functioning of exoskeletal joints can involve hydrostatic forces, depending on the structure of the rigid elements and the type of linkage between them.