Time-domain approach to microwave circuit modeling: A view of general relations between TLM and FDTD (Invited article)

The author's research on the time-domain methods for electromagnetic simulation is reported with focus on the expanded-node FDTD and TLM approaches. The theorem of formal equivalence of FDTD and TLM together with its fundamental consequences (published recently or yet unpublished) is summarized. As an example of application of the theorem, a new family of nonequidistant TLM algorithms with controlled stability margin is originally derived by transformation from FDTD. Several meshing techniques for the modeling of irregular geometries are compared, and the locally modified grids based on local integral approximations are shown to provide optimum accuracy to computer resources ratio for practical microwave problems. © 1996 John Wiley & Sons, Inc.     

Recombination and Pol ζ Rescue Defective DNA Replication upon Impaired CMG Helicase—Pol ε Interaction

The CMG complex (Cdc45, Mcm2–7, GINS (Psf1, 2, 3, and Sld5)) is crucial for both DNA replication initiation and fork progression. The CMG helicase interaction with the leading strand DNA polymerase epsilon (Pol ε) is essential for the preferential loading of Pol ε onto the leading strand, the stimulation of the polymerase, and the modulation of helicase activity. Here, we analyze the consequences of impaired interaction between Pol ε and GINS in Saccharomyces cerevisiae cells with the psf1-100 mutation. This significantly affects DNA replication activity measured in vitro, while in vivo, the psf1-100 mutation reduces replication fidelity by increasing slippage of Pol ε, which manifests as an elevated number of frameshifts. It also increases the occurrence of single-stranded DNA (ssDNA) gaps and the demand for homologous recombination. The psf1-100 mutant shows elevated recombination rates and synthetic lethality with rad52Δ. Additionally, we observe increased participation of DNA polymerase zeta (Pol ζ) in DNA synthesis. We conclude that the impaired interaction between GINS and Pol ε requires enhanced involvement of error-prone Pol ζ, and increased participation of recombination as a rescue mechanism for recovery of impaired replication forks.     

Modification of Pt nanoparticles with polyoxometallate monolayers: Competition between activation and blocking of reactive sites for the electrocatalytic oxygen reduction

Surfaces of bulk platinum and unsupported (Vulcan-free) Pt nanoparticles, that are modified and stabilized with such Keggin type heteropolyacids of molybdenum and tungsten as H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀, have been characterized using cyclic voltammetry, FTIR (by reflectance), as well as transmission and scanning electron microscopies. The presence of the polyoxometallate monolayer on platinum results in the partial suppression of the interfacial formation of PtOH/PtO oxides. Both molybdates and tungstates seem to interact with Pt surface via their corner oxygen atoms. The existence of spacious, largely hydrated, polyoxometallate monolayers on platinum does not block access of reactant (oxygen) to the catalytic Pt sites. The electrocatalytic properties of H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ modified Pt nanoparticles towards reduction of oxygen in acid medium have been examined and compared using rotating ring-disk voltammetry. Reactivity of Pt-free H₃PMo₁₂O₄₀ and H₃PW₁₂O₄₀ with respect to reduction of hydrogen peroxide has also been considered. Our results clearly show that modification of Pt nanoparticles with PW₁₂ (but not with PMo₁₂) results in the enhancement of the electrocatalytic reduction of oxygen.     

Single-mode operation of a long-pulse flashlamp pumped dye laser

We describe the achievement of single-mode operation of a flashlamp pumped long-pulse, ~700 ns dye laser, with output energy of about 350 mJ using a linear optical cavity with a “twisted mode” configuration. Measurements indicate that the laser frequency chirps by about 40 MHz over the entire pulse. Homodyne measurements indicate that the instantaneous bandwidth is close to the transform limit. This represents a significant advance in dye laser performance     

A model-based DSS for integrating the impact of learning in project control

Earned Value Method (EVM) is a popular project control technique. In this paper, we discuss the extended version of EVM (EVM/LC) that addresses the effect of learning on the performance of project teams. These effects have so far been ignored in most EVM applications. We present a spreadsheet-based decision support tool that automates the calculations and analyses in EVM/LC. Using this tool would save the project manager from having to perform complicated calculations while still taking advantage of the relatively accurate estimates generated by EVM/LC. Consequently, this paper contributes to both research and practice in project management.     

An event routing service for distributed applications: computer telephony—a case study

This paper presents an event routing service (ERS) that represents a pattern for the establishment and processing of lightweight sessions between a source and a destination of events. It is based on the CORBA notification service. To illustrate the features of the proposed service, its application in computer telephony is discussed in detail. Most of the positive features of the ERS are inherited from the CORBA notification service, but its implementation requires a novel protocol describing the lightweight session establishment mechanism. The implementation of ERS is described and its application to routing events in a computer telephony system is presented. The paper concludes with a performance measurement study. Copyright © 2002 John Wiley & Sons, Ltd.     

Elimination of microcystins by water treatment processes-examples from Sulejow Reservoir, Poland

Eutrophication is a serious problem in Polish freshwaters. Mass occurrences of toxic cyanobacteria in reservoirs cause problems in the production of safe drinking water and the diversity of produced toxins complicates monitoring of freshwaters. The aim of this study was to estimate the efficiency of water treatment processes in the removal of microcystins (MCs), cyanobacterial hepatotoxins. Elimination of microcystins was studied at two waterworks, which supply drinking water to the city of Lodz from Sulejow Reservoir. The consecutive steps of pre-oxidation, coagulation, sand filtration, ozonation and chlorination used in the water treatment showed effective elimination of microcystins in water from Sulejow Reservoir in 2002 and 2003. The highest total concentration of microcystin (variants MC-RR, MC-YR, MC-LR) amounted to 6.7 microgl(-1) in raw water and was detected on the 13th of August 2002. In 2003 the water utility decided to increase the contribution of ground water in the production of drinking water. This resulted in a decrease of microcystin in water during and after the treatment process. The current management strategy of the waterworks company includes mixing of surface water and ground water, which reduces the hazards caused by toxic cyanobacterial blooms in the reservoir.     

Prediction of Pectin Yield and Quality by FTIR and Carbohydrate Microarray Analysis

Pectin production is complex, and final product quality assessment is generally accomplished at the end of the process using time-consuming off-line laboratory analysis. In this study, pectin was extracted from lime peel either by acid or by enzymes. Fourier transform infrared spectroscopy and carbohydrate microarray analysis were performed directly on the crude lime peel extracts during the time course of the extractions. Multivariate analysis of the data was carried out to predict final pectin yields. Fourier transform infrared spectroscopy (FTIR) was found applicable for determining the optimal extraction time for the enzymatic and acidic extraction processes, respectively. The combined results of FTIR and carbohydrate microarray analysis suggested major differences in the crude pectin extracts obtained by enzymatic and acid extraction, respectively. Enzymatically extracted pectin, thus, showed a higher degree of esterification (DE 82 %) than pectin extracted by acid (DE 67 %) and was moreover found to be more heterogeneously esterified when probed with the monoclonal antibodies JIM5, JIM7, and LM20. The data infer that enzymatic pectin extraction allows for extraction of complex, high DE pectin, and that FTIR and carbohydrate microarray analysis have potential to be developed into online process analysis tools for prediction of pectin extraction yields and pectin features from measurements on crude pectin extracts.