Correlation Analysis of Large-Span Cable-Stayed Bridge Structural Frequencies with Environmental Factors Based on Support Vector Regression.

The dynamic characteristics of bridge structures are influenced by various environmental factors, and exploring the impact of environmental temperature and humidity on structural modal parameters is of great significance for structural health assessment. This paper utilized the Covariance-Driven Stochastic Subspace Identification method (SSI-COV) and clustering algorithms to identify modal frequencies from four months of acceleration data collected from the health monitoring system of the Jintang Hantan Twin-Island Bridge. Furthermore, a correlation analysis is conducted to examine the relationship between higher-order frequency and environmental factors, including temperature and humidity. Subsequently, a Support Vector Machine Regression (SVR) model is employed to analyze the effects of environmental temperature on structural modal frequencies. This study has obtained the following conclusions: 1. Correlation analysis revealed that temperature is the primary influencing factor in frequency variations. Frequency exhibited a strong linear correlation with temperature and little correlation with humidity. 2. SVR regression analysis was performed on frequency and temperature, and an evaluation of the fitting residuals was conducted. The model effectively fit the sample data and provided reliable predictive results. 3. The original structural frequencies underwent smoothing, eliminating the influence of temperature-induced frequency data generated by the SVR model. After eliminating the temperature effects, the fluctuations in frequency within a 24 h period significantly decreased. The data presented in this paper can serve as a reference for further health assessments of similar bridge structures.

Molecular typing of Vibrio parahaemolyticus isolates from the middle-east coastline of China.

The occurrence of outbreaks of Vibrio parahaemolyticus gastroenteritis in China highlights the need for strain characterization and subtyping of this pathogenic species. A total of 56 epidemiologically-unrelated strains of V. parahaemolyticus were isolated from clinical samples, seafood and various environmental sites in the middle-east coastline of China from 2006 to 2008. The isolates were characterized using four molecular typing methods, including ribotyping, enterobacterial repetitive intergenic consensus sequence PCR (ERIC-PCR), pulsed-field gel electrophoresis (PFGE), and sequence analysis of the gyrB gene. Genetic profiles of cluster analysis from these molecular typing tests clearly showed that there were differences in potential pathogenicity among isolates from seafood and its environments. Genetic characterization of two isolates (F13 and QS2) that originated from seafood demonstrated that they were potentially pathogenic. Discriminatory indices of four typing methods for the 56 V. parahaemolyticus isolates were differentiated by Simpson's Index of Diversity. The discriminatory index of ERIC-PCR typing was maximal (D=0.942), while that of sequence analysis of the gyrB gene was minimal (D=0.702). The discriminatory ability was greatly enhanced (D=0.966) when ERIC-PCR was coupled with sequence analysis of the gyrB gene. These results suggest that ERIC-PCR combined with sequence analysis of gyrB gene may be a reliable, rapid typing strategy for V. parahaemolyticus strains.

[Investigating the toxicity characteristics of Nassarius Sp. in Ningbo City].

OBJECTIVE: To study the type, distribution, the growth and decline of toxins in Nassarius Sp. and the source of toxins to acquire the basis for the control of Nassarius Sp. poisonings. METHODS: The toxicity of Nassarius Sp. was detected by mouse bioassay. The saxitoxin (STX), gonyau toxin (GTX), and tetrodo toxin (TTX) were detected by ELISA and HPLC. RESULTS: Sixty-three poisonous Nassarius Sp. were identified in 127 samples collected from long-term monitoring sites. The detection rate was 49.6%. The detection rate of poisonous Nassarius Sp. was different in varies habitats (P < 0.01). The toxicity of Nassarius Sp. reached a peak in 1991 and hit the rock bottom in 1988. The rate of carrying toxins and the toxicity of detected toxins (STX, GTX and TTX) in Nassarius semiplicatus, Nassa succincta A. Adams and Niotha livescens were high. CONCLUSION: The toxins of Nassarius Sp. in Ningbo City were composed of TTX, STX or GTX, or both TTX and STX. The surveillance proved that some toxins present in Nassarius Sp. in Ningbo City. Poisoning could be caused by eating Nassarius Sp.

[Epidemiological and etiological characteristics of typhoid and paratyphoid fever in Ningbo during 1988 - 2007].

OBJECTIVE: To study the epidemiological and etiological characteristics of typhoid and paratyphoid fever in high epidemic areas. METHODS: Reported data on typhoid and paratyphoid fever during 1988-2007 in Ningbo were analyzed epidemiologically. Shellfish from the market was collected for laboratory testing and Salmonella typhi strains collected from the patients were also studied. RESULTS: Number of reported cases on both typhoid and paratyphoid fever was 19 404 with 7 deaths, from 1988 to 2007. The annual mean incidence was 17.68 per one hundred thousand with the fatality rate as 0.36 per thousand. Most cases were among adults aged 20-50 years and an obvious regional distribution was observed with high incidence seen in winter and spring. Since 1990s, the advantage strain had changed from Salmonella typhi to Salmonella paratyphi A. Etiologic studies showed that raw Anadara subcrenata and oyster were the main risk factors. One Salmonella paratyphi A strain was detected in both Anadara subcrenata and oysters collected from the market, which contained TEM-1 drug resistance gene. PFGE genotyping showed that PFGE-X2 was the strain which causing pandemic in Ningbo. CONCLUSION: Eating contaminated raw shellfish like oysters and hairy clams was the primary risk factor, responsible for the outbreaks. Salmonella paratyphi A was the advantages pandemic strain in Ningbo. Strategies as supervision on personal hygiene and health education should be strengthened.

[Study of ALAD and VDR gene polymorphisms associated with lead nephrotoxicity susceptibility].

OBJECTIVE: To explore lead nephrotoxicity associated with delta-aminolevulinic acid dehydratase, vitamin D receptor gene polymorphism as well as joint effect of gene-gene, gene-environment. METHODS: 233 occupational lead-exposed workers were involved in this study. Then blood lead was detected as lead exposure biomarker. Urinary N-acetyl-beta-D-glucosamindase and beta2-microglobin of those workers were measured as biomarkers of nephrotoxicity. PCR-RFLP method was used for gene polymorphism analysing. RESULTS: Lead exposure concentration was higher than national limit, NAG acticity were (2.12 +/- 0.07) U/mmol Cr in workers with ALAD1-2/ALAD2-2 genotype and (1.73 +/- 0.03) U/mmol Cr in workers with ALAD1-1 genotype (P < 0.05). In the same condition, beta2-MG were (20.94 +/- 1.12) microg/mmol Cr in workers with VDR-Bb genotype and (15.28 +/- 0.09) microg/mmol Cr in workers with VDR-bb genotype (P = 0.01). Analysis of logistic regression confirmed that lead exposure and high blood lead as well as combined effect of gene-environment were responsible for lead nephrotoxicity in workers (OR = 6.58, 2.41, 3.01). CONCLUSION: Polymorphisms of ALAD and VDR gene may play an important role in lead nephrotoxicity in high lead-exposed workers. Joint effect of gene-environment could be involved in lead nephrotoxicity in workers.

[Analysis of beta-lactams-resistance genes in Pseudomonas aeruginosa in burn ward].

OBJECTIVE: To investigate the resistance genes and antibiotic resistance patterns against beta-lactams in Pseudomonas aeruginosa prevalent in burn ward. METHODS: K-B method was performed to test bacterial resistance patterns against 9 species of beta-lactams in Pseudomonas aeruginosa isolated from wounds and dressings of the patient in burn wards. Seven species of resistance genes against beta-lactams were detected with PCR. Tazobactam-inhibited piperacillin resistance test was performed to study whether the above strains produce extended spectrum beta-lactams. RESULTS: All 12 strains of bacteria with resistance genes detected were resistant to penicillin and cephalosporins (100%), among them 11 were resistant to all antibiotics. Tazobactam-inhibited piperacillin resistance test demonstrated that all strains with resistance genes were ESBLs. CONCLUSION: High incidence of beta-lactams resistance genes is found in Pseudomonas aeruginosa isolated from burn ward, and they have close relationship with the occurrence of multiple drug-resistance.