Improved Compartmental Modeling and Application to Three-Phase Contaminant Transport in Unsaturated Porous Media

The compartmental modeling approach has been widely used for simulating contaminant transport in porous media and surface waters. Yet a commonly used compartmental model that has only first-order accuracy may introduce considerable numerical errors under certain circumstances. Following a review of compartmental systems and compartmental modeling methodologies, performance and limitations of such a compartmental model are discussed. In particular, improvement approaches, including multipoint, high-order, linear, and nonlinear methods, are presented in detail. Finally, a number of testing problems are examined and various compartmental models that describe three-phase (dissolved, adsorbed, and vapor phases) contaminant transport in unsaturated porous media are compared with each other and also with standard numerical and analytical counterparts. The comparisons highlight the accuracy, applicability, and limitations of different compartmental models.     

CD10 is expressed on human thymic epithelial cell lines and modulates thymopentin-induced cell proliferation

Thymic hormones such as thymopoietin (TP) have been shown to regulate thymocyte differentiation and lymphocyte activation. However, it is not known whether thymopoietin affects thymic epithelial cell (TEC) functions. In this study we have examined the effect of a five amino acid active peptide (TP5), corresponding to amino acids 32-36 of TP, on the proliferation of nontransformed clones of human TEC. Our results indicate that TP5 induced reinitiation of DNA synthesis and potentiated fetal calf serum (FCS)-induced cell growth in postnatal and fetal-derived human TEC. We also found that TEC lines express high levels of endopeptidase 24.11, a cell-surface metallopeptidase also known as the CD10 antigen. We show that TP5 is cleaved by CD10 at the surface of TEC lines, indicating that this endopeptidase may regulate TP5-induced TEC proliferation. Phosphoramidon, a specific endopeptidase 24.11 inhibitor, consistently acts in synergy with TP5 to enhance FCS-induced TEC growth. Hence, we conclude that 1) TP5 alone or in combination with FCS supports the growth of TEC lines, and 2) TEC lines express high levels of CD10, which regulates TP5-induced TEC proliferation by acting as a thymic peptide degrading enzyme.     

The N-terminal half of the influenza virus NS1 protein is sufficient for nuclear retention of mRNA and enhancement of viral mRNA translation

A collection of C-terminal deletion mutants of the influenza A virus NS1 gene has been used to define the regions of the NS1 protein involved in its functionality. Immunofluorescence analyses showed that the NS1 protein sequences downstream from position 81 are not required for nuclear transport. The capacity of these mutants to bind RNA was studied by in vitro binding tests using a model vRNA probe. These experiments showed that the N-terminal 81 amino acids of NS1 protein are sufficient for RNA binding activity. The collection of mutants also served to map the NS1 sequences required for nuclear retention of mRNA and for stimulation of viral mRNA translation, using the NP gene as reporter. The results obtained indicated that the N-terminal 113 amino acids of NS1 protein are sufficient for nuclear retention of mRNA and stimulation of viral mRNA translation. The possibility that this region of the protein may be sufficient for virus viability is discussed in relation to the sequences of NS1 genes of field isolates and to the phenotype of known viral mutants affected in the NS1 gene.     

A counterexample in power signals space

The present author points out that in the paper by Vidyasagar (1993) on nonlinear system analysis, some of the results obtained are false. The purpose of this paper is to give a counterexample. It is shown that the set of power signals is not a vector space     

High temperature deformation mechanisms in cemented carbides and cermets studied by mechanical spectroscopy

Two model hardmetals, a pure WC–Co and a TiWCN–Co, have been studied by mechanical spectroscopy. In this work, the materials are studied up to 0.85T_m of cobalt. A parallel analysis of the materials shows that three domains are characterized by similar internal friction peaks. A region characterized by relaxations in Co, a region characterized by relaxations in the ceramics and a high-temperature region characterized by relaxations at grain boundaries are found. Two peaks are located at high temperatures in both materials. The first located at 1420 K in WC–Co and at 1520 K in TiWCN–Co for 1 Hz is attributed to grain boundary sliding. A very broad and high peak estimated for 1 Hz around 1600 K in WC–Co and above 1700 K in TiWCN–Co has only been directly observed in frequency. It is thermally activated and shows a high, apparent activation energy.     

Optimization of a K-on-N configuration

A new class of redundant systems called the K-on-N configuration is introduced here. Realistic design features are developed for the available resources to build a highly reliable system. An easily programmed algorithm due to Lawler and Bell is adapted to solve the optimization problem. The method is applied for reliability improvement of a real-life system problem.     

Review of the Stanford-Binet Intelligence Scale: Fourth edition.

This article discusses the Stanford-Binet, Fourth Edition (1986). Psychologists using it for the first time may be surprised to discover that the test resembles a new test more than a revision of the old instrument. Differences between this edition and earlier versions are noted. For example, reliance on age levels is gone from the new test. Other changes in test format are discussed. Also noted are problems the test presents for the examiner. For example, instructions and scoring guidelines are sometimes inadequate. The article reviews the adequacy of the technical manual, standardization of the test, the internal consistency reliability of this Fourth Edition, and its validity. The reviewers suggest that practitioners may wish to become well-acquainted with the new Stanford-Binet so that its use might be an option for them, but they should not give the test a superior rating just because of its name. Given the hefty cost of the instrument and the time needed to master it, potential users with limited budgets and limited time may well find that their evaluation needs can be adequately filled by using another test of cognitive ability already in their possession. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

On the accurate calibration of an electrochemical oxygen meter in the 10−7 bar range

A method for the accurate standardization of an electrochemical oxygen meter, in the 10^–6-10^–7 bar range is described. The method is based on the use of an electrochemical oxygen leak and a chemical getter pump. In this manner problems connected with traces of hydrogen, originating from the pyrolysis of water, and traces of oxygen of unknown origin are overcome.