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W Z Lu

Publications and source records attributed to W Z Lu.

6 recordsLinked to original sources
PubMed2003

Using improved neural network model to analyze RSP, NOx and NO2 levels in urban air in Mong Kok, Hong Kong.

As the health impact of air pollutants existing in ambient addresses much attention in recent years, forecasting of air pollutant parameters becomes an important and popular topic in environmental science. Airborne pollution is a serious, and will be a major problem in Hong Kong within the next few years. In Hong Kong, Respirable Suspended Particulate (RSP) and Nitrogen Oxides NOx and NO2 are major air pollutants due to the dominant diesel fuel usage by public transportation and heavy vehicles. Hence, the investigation and prediction of the influence and the tendency of these pollutants are of significance to public and the city image. The multi-layer perceptron (MLP) neural network is regarded as a reliable and cost-effective method to achieve such tasks. The works presented here involve developing an improved neural network model, which combines the principal component analysis (PCA) technique and the radial basis function (RBF) network, and forecasting the pollutant levels and tendencies based in the recorded data. In the study, the PCA is firstly used to reduce and orthogonalize the original input variables (data), these treated variables are then used as new input vectors in RBF neural network model established for forecasting the pollutant tendencies. Comparing with the general neural network models, the proposed model possesses simpler network architecture, faster training speed, and more satisfactory predicting performance. This improved model is evaluated by using hourly time series of RSP, NOx and NO2 concentrations collected at Mong Kok Roadside Gaseous Monitory Station in Hong Kong during the year 2000. By comparing the predicted RSP. NOx and NO2 concentrations with the actual data of these pollutants recorded at the monitory station, the effectiveness of the proposed model has been proven. Therefore, in authors' opinion, the model presented in the paper is a potential tool in forecasting air quality parameters and has advantages over the traditional neural network methods.

Air Pollutants↗
PubMed2002

Analysis of pollutant levels in central Hong Kong applying neural network method with particle swarm optimization.

Air pollution has emerged as an imminent issue in modern society. Prediction of pollutant levels is an important research topic in atmospheric environment today. For fulfilling such prediction, the use of neural network (NN), and in particular the multi-layer perceptrons, has presented to be a cost-effective technique superior to traditional statistical methods. But their training, usually with back-propagation (BP) algorithm or other gradient algorithms, is often with certain drawbacks, such as: 1) very slow convergence, and 2) easily getting stuck in a local minimum. In this paper, a newly developed method, particle swarm optimization (PSO) model, is adopted to train perceptrons, to predict pollutant levels, and as a result, a PSO-based neural network approach is presented. The approach is demonstrated to be feasible and effective by predicting some real air-quality problems.

Air Pollutants↗
PubMed2001

[Model transfer in multivariate calibration].

This paper introduces the backgrounds, principles and some popular algorithms used for resolving calibration transfer in multivariate calibration of chemometrics. The algorithms include S/B, DS, PDS, FIR, and Shenk's algorithm. The recent development of calibration transfer in the past two years is also reviewed. A number of key applications of different calibration transfer algorithms are summarized, which will be helpful for the further research of calibration transfer principles and algorithms. 51 references are cited.

Algorithms↗
PubMed1994

BCL2 translocations in leukemias of mature B cells.

Although translocations of the BCL2 gene are frequent in B-cell non-Hodgkin's lymphomas (B-NHL) the incidence, nature, and prognostic significance of similar translocations in the phenotypically related chronic leukemias of mature B cells are unknown. Therefore, we examined 170 cases of B-cell chronic lymphocytic leukemia (B-CLL), 7 cases of B-cell prolymphocytic leukemia (B-PLL), 25 cases of hairy cell leukemia (HCL) and 22 cases of splenic lymphoma with villous lymphocytes (SLVL) with defined cytogenetic abnormalities by DNA blot using both 5' and 3' BCL2 probes to search for rearrangement of the BCL2 locus. Translocation t(14;18) (q32.3;q21.3) was detected cytogenetically in 3 cases of B-CLL. All had breakpoints in the 3' region of BCL2, mapping between the major breakpoint region (MBR) and the minor cluster region (mcr), the breakpoint clusters commonly detected in B-NHL. In 2 of the 3 cases, the breakpoint within BCL2 was mapped to a 1.0-kb EcoRI-HindIII fragment indicating a clustering of breakpoints. Two cases of B-CLL had cytogenetically detectable t(2;18)(p11;q21.3) or t(18;22)(q21.3;q11). Both had rearranged the 5' region of the BCL2 gene to the corresponding lg light-chain gene. Molecular cloning of the t(18;22)(q21.3;q11) showed that the translocation disrupted the BCL2 promoter region and the first untranslated BCL2 exon. Nevertheless, high levels of BCL2 protein were seen in this case. Only 2 other cases in whom cytogenetic analysis was not successful showed rearrangement of the 5' region of BCL2, an overall incidence of 2.3%. No cases of B-PLL, HCL, or SLVL showed either 5' or 3' BCL2 rearrangement. These data confirm the cytogenetic observations that translocations involving the BCL2 locus in all forms of leukemia of mature B cells are rare, and limited to a minor subset of B-CLL. BCL2 translocations in B-CLL involve hot spots of recombination of both the 5' and 3' regions of the BCL2 gene, which are distinct from those commonly seen in B-NHL, suggesting distinct pathogenic mechanisms.

Aged↗
PubMed1991

Production of antigen-specific human monoclonal antibodies from in vitro-primed human splenocytes.

We have developed culture conditions for human lymphocytes that support primary in vitro immune responses to protein Ag of either human or nonhuman origin. We now show that these primed B cells can be efficiently immortalized by fusion with a heterohybrid fusion partner to generate human, Ag-specific IgM or IgG antibody-producing heterohybridomas at a rate of 17 to 50 hybrids/10(6) lymphocytes fused. Approximately 50% of the Ig-secreting clones were stable with respect to Ig secretion. Levels of secretion attained with terminal cultures ranged from less than 1 to 100 micrograms/ml. Fusions of cells between 2 and 5 days after initiation of in vitro exposure to Ag produced more Ag-reactive and Ag-specific antibodies than fusions at 1 day or fusions performed after 5 days. Ag-reactive hybrids could be isolated at frequencies of 3 to 10%, depending on antigenicity of the immunogen. Foreign proteins, horse spleen ferritin, and a murine monoclonal Ig, induced higher percentages of Ag-reactive mAb than immunization with the human-derived ferritin. Ag-reactive IgG mAb were produced at relatively high frequency, depending on immunization conditions and the nature of the Ag. The strategy for identification of the best hybrids included early elimination of unstable hybridomas and of hybridomas producing broadly cross-reactive antibody, followed by evaluation of units of Ag reactivity/micrograms Ig. Ferritin-specific mAb selected according to these criteria showed immunocytochemical reactivity with ferritin-containing tissues and apparent affinities in the range of 10(7) to 10(8)/mol.

Animals↗