A MOMENT MATCHING APPROACH FOR MODELLING ATM CELL ARRIVAL PROCESSES

This paper presents a moment matching approach for constructing an equivalent model of an ATM cell arrival process based on inter-cell arrival time measurement. As compared to a renowned parameter-matching technique proposed by Heffes and Lucatoni, the advantage of this approach is that the matching parameters are more easily obtained in real traffic situation. This approach has been tested on an MMBP^[Poisson] process, and results show that only the first four moments are required to capture the key characteristics in this process.     

Application of a Novel Method for Machine Performance Degradation Assessment Based on Gaussian Mixture Model and Logistic Regression

The currently prevalent machine performance degradation assessment techniques involve estimating a machine’s current condition based upon the recognition of indications of failure features,which entail complete data collected in different conditions.However,failure data are always hard to acquire,thus making those techniques hard to be applied.In this paper,a novel method which does not need failure history data is introduced.Wavelet packet decomposition(WPD) is used to extract features from raw signals,principal component analysis(PCA) is utilized to reduce feature dimensions,and Gaussian mixture model(GMM) is then applied to approximate the feature space distributions.Single-channel confidence value(SCV) is calculated by the overlap between GMM of the monitoring condition and that of the normal condition,which can indicate the performance of single-channel.Furthermore,multi-channel confidence value(MCV),which can be deemed as the overall performance index of multi-channel,is calculated via logistic regression(LR) and that the task of decision-level sensor fusion is also completed.Both SCV and MCV can serve as the basis on which proactive maintenance measures can be taken,thus preventing machine breakdown.The method has been adopted to assess the performance of the turbine of a centrifugal compressor in a factory of Petro-China,and the result shows that it can effectively complete this task.The proposed method has engineering significance for machine performance degradation assessment.     

Purification and characterization of MAR1. A mitochondrial associated ribonuclease from Leishmania tarentolae

A relatively thermostable 22-kDa endoribonuclease (MAR1) was purified more than 10,000-fold from a mitochondrial extract of Leishmania tarentolae and the gene cloned. The purified nuclease has a Km of 100-145 +/- 33 nM and a Vmax of 1.8-2.9 +/- 2 nmol/min, depending on the RNA substrate, and yields a 3'-OH and a 5'-phosphate. Cleavage was limited to several specific sites in the substrate RNAs tested, but cleavage of pre-edited RNAs was generally independent of the addition of cognate guide RNA. The MAR1 gene was expressed in Escherichia coli or in L. tarentolae cells, and the recombinant protein was affinity-purified. The cleavage specificity of the recombinant enzyme from L. tarentolae was identical to that of the native enzyme. The single copy MAR1 gene maps to an 820-kilobase pair chromosome and contains an open reading frame of 579 nucleotides. The 18-amino acid N-terminal sequence shows characteristics of an uncleaved mitochondrial targeting sequence. Data base searching revealed two homologues of MAR1 corresponding to unidentified open reading frames in Caenorhabditis elegans (GenBankTM accession number Z69637) and Archaeoglobus fulgidus (GenBankTM accession number AE000943). The function of MAR1 in mitochondrial RNA metabolism in L. tarentolae remains to be determined.     

Expression of E-selectin, sialyl Lewis X, and macrophage inflammatory protein-1alpha by colonic epithelial cells in ulcerative colitis

The pathogenic significance of cell adhesion molecules (CAMs) in ulcerative colitis (UC) is largely unknown. Colonic expression of E-selectin, sialyl Lewis X (sLe(x)), and macrophage inflammatory protein-1x (MIP-1alpha) as well as serum concentrations of E-selectin and MIP-1alpha in UC were studied. Thirty patients with UC, 10 patients with irritable bowel syndrome, and 10 healthy subjects were included. Colonic biopsies were stained immunohistochemically, and blood concentrations were measured with an ELISA technique. Soluble E-selectin did not correlate with diagnosis or disease activity. MIP-1alpha was below the detection limit. Epithelial cells expressed all three molecules, both on surface membranes and intracellularly. sLe(x) staining was weaker (P = 0.0002) and MIP-1alpha staining stronger (P = 0.014) in UC patients than in controls. Leukocyte MIP-alpha staining correlated with diagnosis (P = 0.021), sLe(x) staining (P = 0.023), and colonoscopy (P = 0.018). It is shown that E-selectin, sLe(x), and MIP-1alpha are synthesized and expressed by epithelial cells, indicating that CAMs are not only involved in leukocyte extravasation and migration, but also in the interaction between leukocytes and colonic epithelium. This knowledge might contribute to the development of improved treatments in UC.     

Human monocyte-derived macrophages express an approximately 120-kD Ox-LDL binding protein with strong identity to CD68

A protein that specifically binds oxidized LDL (Ox-LDL) has recently been characterized in mouse peritoneal macrophages and identified as macrosialin, a protein with a molecular weight of 95 kD. First, the present work shows that human monocyte-derived macrophages express a membrane protein with a molecular weight of approximately 120 kD that selectively binds Ox-LDL. Second, we tested whether this approximately 120-kD Ox-LDL binding protein had any relation to CD68, the human homologue of macrosialin. The following evidence was obtained to support the role of CD68 as an Ox-LDL binding protein: (1) Ligand blots with Ox-LDL and Western blots with Ki-M6, an anti-human CD68 monoclonal antibody, revealed a single band with a molecular weight of approximately 120 kD under reducing and nonreducing condition. (2) The expression patterns of the approximately 120-kD Ox-LDL binding membrane protein and of CD68 paralleled each other during monocyte/macrophage differentiation. (3) Digestion with N-glycosidase F demonstrated that both CD68 and the Ox-LDL binding protein are glycoproteins; both showed a similar shift of approximately 18 kD in apparent molecular weight. (4) CD68, probed with monoclonal antibody Ki-M6, and the approximately 120-kD Ox-LDL binding protein were coprecipitated with EMB11, another anti-CD68 antibody. About 5000 molecules of CD68 are expressed on the cell surface of human macrophages. Ligation of 125I-Ki-M6 to cells leads to its internalization and degradation. This capacity would be sufficient to allow for the specific uptake and degradation of Ox-LDL. Taken together, these data support a role for CD68 as a specific Ox-LDL binding protein in human monocyte-derived macrophages.     

Edible mushroom (Agaricus bisporus) lectin, which reversibly inhibits epithelial cell proliferation, blocks nuclear localization sequence-dependent nuclear protein import

The Galbeta1-3GalNAcalpha (TF antigen)-binding lectin (ABL) from the common edible mushroom (Agaricus bisporus) has a potent anti-proliferative effect without any apparent cytotoxicity. This unusual combination of properties prompted investigation of its mechanism of action. In contrast to soluble lectin, agarose-immobilized, and hence noninternalizable ABL had no effect on proliferation of HT29 colon cancer cells. Electron microscopy of HT29 cells incubated with fluorescein- and gold-conjugated ABL showed internalization of the lectin into endocytotic vesicles and multivesicular bodies. Confocal microscopy showed perinuclear accumulation of fluorescein isothiocyanate-conjugated lectin, which also inhibits HT29 cell proliferation, raising the possibility that the lectin might interfere with nuclear pore function. Transport of heat shock protein 70 into the nucleus in response to heat shock was blocked by preincubation of HT29 cells for 6 h with 40 micrograms/ml ABL. In digitonin-permeabilized cells, nuclear uptake of bovine albumin conjugated to a nuclear localization sequence (NLS)-containing peptide was also inhibited by a 15-min preincubation with 40-100 micrograms/ml ABL. In contrast, serum-stimulated nuclear translocation of mitogen-activated protein kinase, which is NLS-independent, was not affected by pretreatment of cells with the lectin. These results suggest that the anti-proliferative effect of ABL is likely to be a consequence of the lectin trafficking to the nuclear periphery, where it blocks NLS-dependent protein uptake into the nucleus.