Variable selection and oversampling in the use of smooth support vector machines for predicting the default risk of companies

In the era of Basel II a powerful tool for bankruptcy prognosis is vital for banks. The tool must be precise but also easily adaptable to the bank's objectives regarding the relation of false acceptances (Type I error) and false rejections (Type II error). We explore the suitability of smooth support vector machines (SSVM), and investigate how important factors such as the selection of appropriate accounting ratios (predictors), length of training period and structure of the training sample influence the precision of prediction. Moreover, we show that oversampling can be employed to control the trade‐off between error types, and we compare SSVM with both logistic and discriminant analysis. Finally, we illustrate graphically how different models can be used jointly to support the decision‐making process of loan officers. Copyright © 2008 John Wiley & Sons, Ltd.     

Lactacystin-induced apoptosis of cultured mouse cortical neurons is associated with accumulation of PTEN in the detergent-resistant membrane fraction

The tumor suppressor function of PTEN is attributed to its phospholipid phosphatase activity that dephosphorylates the plasma membrane phosphatidylinositol-(3,4,5)-triphosphate [PtdIns(3,4,5)P₃]. Implicit in this notion is that PTEN needs to be targeted to the plasma membrane to dephosphorylate PtdIns(3,4,5)P₃. However, the recruitment of PTEN to the plasma membrane is not fully understood. Here, we demonstrate PTEN accumulation in the detergent-insoluble fraction of neuronal cells in response to treatment by the proteasome inhibitor lactacystin. First, lactacystin induces apoptosis and the activation of caspase-3 in cultured cortical neurons. Second, PTEN undergoes proteolysis to form a truncated 50-kDa form that lacks parts of its C-terminal tail. Third, the truncated PTEN is stably associated with the detergent-insoluble fraction in which the plasma membrane marker protein flotillin-1 resides. Taken together, our results suggest that truncation and accumulation of PTEN to the detergent-insoluble membrane fraction are two events associated with the apoptotic signals of the proteasome inhibitor in cortical neurons.Received 24 March 2004; received after revision 26 May 2004; accepted 5 June 2004     

番木瓜细胞形态变化与蛋白酶积累过程的研究

番木瓜细胞在含0.1mg/L NAA、0.5mg/L 6—BA的B_5培养基中,25℃避光培养。随着培养的继续,细胞形态发生变化。用电子显微镜扫描观察,培养前二十天,细胞处于生长旺盛阶段,形态饱满、密度大、生命力强,代谢旺盛,大量积累木瓜蛋白酶。培养十八天的蛋白酶比活力为209.1 U/mg·蛋白,比产率为4.04 U/g·day,是天然木瓜乳汁中的6.31倍和130%。当细胞开始分化或衰老时,木瓜蛋白酶的积累能力减弱。     

Personalized Metaheuristic Clustering Onto Web Documents

Optimal clustering for the web documents is known to complicated combinatorial Optimization problem and it is hard to develop a generally applicable oplimal algorithm. An accelerated simuIated arlneaIing aIgorithm is developed for automatic web document classification. The web document classification problem is addressed as the problem of best describing a match between a web query and a hypothesized web object. The normalized term frequency and inverse document frequency coetficient is used as a measure of the match. Test beds are generated on - line during the search by transforming model web sites. As a result,web sites can be clustered optimally in terms of keyword vectors of corresponding web documents.     

Energy-dependent regulation of cell structure by AMP-activated protein kinase

AMP-activated protein kinase (AMPK, also known as SNF1A) has been primarily studied as a metabolic regulator that is activated in response to energy deprivation. Although there is relatively ample information on the biochemical characteristics of AMPK, not enough data exist on the in vivo function of the kinase. Here, using the Drosophila model system, we generated the first animal model with no AMPK activity and discovered physiological functions of the kinase. Surprisingly, AMPK-null mutants were lethal with severe abnormalities in cell polarity and mitosis, similar to those of lkb1-null mutants. Constitutive activation of AMPK restored many of the phenotypes of lkb1-null mutants, suggesting that AMPK mediates the polarity- and mitosis-controlling functions of the LKB1 serine/threonine kinase. Interestingly, the regulatory site of non-muscle myosin regulatory light chain (MRLC; also known as MLC2) was directly phosphorylated by AMPK. Moreover, the phosphomimetic mutant of MRLC rescued the AMPK-null defects in cell polarity and mitosis, suggesting MRLC is a critical downstream target of AMPK. Furthermore, the activation of AMPK by energy deprivation was sufficient to cause dramatic changes in cell shape, inducing complete polarization and brush border formation in the human LS174T cell line, through the phosphorylation of MRLC. Taken together, our results demonstrate that AMPK has highly conserved roles across metazoan species not only in the control of metabolism, but also in the regulation of cellular structures.     

Operator scheduling strategy for LBS based intelligent transportation system

With the development of location technologies, advanced LBSbased ITS increasingly requires the capability of database technologies to manage the continuously arrived vehicles' location, traffic jam and other interrelated information of large amounts of traffic in the following years. And some burst arrival stream data will challenge the realtime performance and the allocation of limited resource. However, choosing a desirable database operator scheduling strategy can significantly improve the performance of the system. The path capability strategy was chosen and improved as ITS' operator scheduling strategy to meet the realtime response and the minimal memory requirement of the system.      

A cellular protein that competes with SV40 T antigen for binding to the retinoblastoma gene product

Tumour-suppressor genes, such as the human retinoblastoma susceptibility gene (Rb), are widely recognized as being vital in the control of cell growth and tumour formation. This role is indicated, in part, by the suppression of tumorigenicity of human tumour cells after retrovirus-mediated Rb replacement. How Rb acts to bring about this suppression is not clear but one clue is that the Rb protein forms complexes with the transforming oncoproteins of several DNA tumour viruses, and that two regions of Rb essential for such binding frequently contain mutations in tumour cells. These observations suggest that endogenous cellular proteins might exist that bind to the same regions of Rb and thereby mediate its function. We report here the identification of one such human cellular Rb-associated protein of relative molecular mass 46,000 (46K) (RbAP46). Two lines of evidence support the notion that RbAP46 and simian virus 40 T antigen have homologous Rb-binding properties: first, several mutated Rb proteins that failed to bind to T also did not associate with RbAP46; and second, both T antigen and T peptide (amino acids 101-118) were able to compete with RbAP46 for binding to Rb. The apparent targeting of the RbAP46-Rb interaction by oncoproteins of DNA tumour viruses strongly suggests that formation of this complex is functionally important.     

Inter-domain routing and wavelength assignment based on source routing in ASON

The inter-domain and intra-domain routings are treated jointly with dynamically distributed algorithms in automatically switched optical networks （ASON） based on source routing. The proposed algorithms are discussed through numerical calculations. The routing loops can be avoided efficiently and the inter-domain signaling complexity is reduced significantly. The performance of the blocking probability is also improved.     

Probing the penicillin sidechain selectivity of recombinant deacetoxycephalosporin C synthase

Deacetoxycephalosporin C synthase from Streptomyces clavuligerus catalyses the conversion of the five-membered penicillin ring to the unsaturated six-membered cephem ring of deacetoxycephalosporin C. The effects on enzyme activity of the penicillin substrate sidechain and various cofactors were investigated using a continuous spectrophotometric assay. The conversion of penicillin G to phenylacetyl-7-aminodeacetoxycephalo sporanic acid (G-7-ADCA) was confirmed, and further details of the reaction were elucidated. The conversion of ampicillin to cephalexin was faster than that of acetyl-6-APA to acetyl-7-ADCA kcat = 0.120 +/- 0.001 s(-1) versus 0.035 +/- 0.001 s(-1), but they had similar Km values: 4.86 +/- 0.12 and 3.28 +/- 0.26 mM, respectively. Amoxycillin and penicillin V were also converted at low levels. Conversion was not detected for penicillanate, 6-aminopenicillanate, carbenicillin, temocillin, ticarcillin or benzylpenicilloic acid, suggesting that the enzyme has a relatively strict selectivity for the sidechain of the penicillin substrate.