食品微生物检测技术研究

随着社会的不断发展,人们对食品安全问题越来越重视,食品在加工过程中,病菌很容易侵袭到食品中,威胁到消费者的饮食安全,因此,食品微生物检测工作显得尤为重要。我国食品微生物检测最常用的方法是琼脂平板培养法,近年来,在各国机构和学者的努力下,食品微生物检测技术有了新的发展,其能更快速、简洁地进行食品微生物检测。食品微生物检验的特点要求高、范围广首先,食品微生物检测范围非常广。

解放思想 开拓创新 为杭州交通跨越式发展保驾护航 杭州市交通工程质量安全监督局

杭州市交通工程质量安全监督局(以下简称质量安监局)成立于1991年4月16日,原名为杭州市交通工程质量监督总站。

Method of spillover identification in urban street networks using loop detector outputs

Quick and reliable identification of the traffic state is of critical importance to traffic control systems, especially when spillovers appear. Firstly, a calculation method for the occupancy per cycle under different traffic conditions were presented, based on the relationship between the three basic traffic flow parameters, speed, traffic flow and density. Secondly, the times at which the stopping and starting waves approach a loop detector were confirmed using the traffic wave models modified by a kinematic equation. Then, the threshold of occupancy, which characterizes the appearance of spillovers, was determined by the premise that the stopping and starting waves had the same speed. At last, the accuracy and usability of the new method were verified by VISSIM simulation, using the ratio of misjudgment as the evaluation index. The results show that the ratio of misjudgment of the new method is about 11.36% compared to 17.65% of the previous method.

Using Impervious Surfaces to Detect Urban Expansion in Beijing of China in 2000s

The change of impervious surface area(ISA) can effectively reveal the gradual process of urbanization and act as a key index for monitoring urban expansion. Experiencing rapid growth of the built environment in the 2000 s, urban expansion of Beijing has not been fully characterized through ISA. In this study, Landsat TM images of Beijing in 2001 and 2009 were obtained, and the eight-year urban expansion process in Beijing was analyzed using the ISA extracted by means of the vegetation-imperious surface-soil(V-I-S) model. From the spatial variation in ISA, the ring structure of urban expansion in Beijing was significant during the study period, with decreasing urban density from the city center to the periphery. In the ring road analysis, the most dramatic changes of ISA were found between the fifth ring and the sixth ring. This area has experienced the most new residential development, and is currently the main source of urban expansion. The typical profile lines revealed the directional characteristics of urban expansion. The east-west profile was the most urbanized axes in Beijing, while ISA change in the east-north profile was more significant than in the other five profiles. Moreover, the transition matrix of ISA levels revealed an increase in urban density in the low density built areas; the Moran′s I index showed a clear expansion of the central urban area, which spread contiguously; and the standard deviational ellipse indicated the northeast was the dominant direction of urban expansion. These findings can provide important spatial control guidelines in the next round of national economic and social development planning, overall urban and rural planning, and land use planning.

Detection of HPV Types and Neutralizing Antibodies in Women with Genital Warts in Tianjin City,China

The serum samples and corresponding cervical swabs were collected from 50 women with genital warts from Tianjin city, China. The neutralizing antibodies against HPV-16, -18, -58, -45, -6 and -11 in serum samples were tested by using pseudovirus-based neutralization assays and HPV DNAs in cervical swabs were also tested by using a typing kit that can detect 21 types of HPV. The results revealed that 36% （18/50） of sera were positive for type-specific neutralizing antibodies with a titer range of 160-2560, of which 22%（11/50）, 12%（6/50）, 10%（5/50）, 4%（2/50）, 4%（2/50） and 2%（1/50） were against HPVs -6, -16, -18, -58, -45 and -1 l, respectively. Additionally, 60% （30/50） of samples were HPV DNA-positive, in which the most common types detected were HPV-68（18%）, HPV-16（14%）, HPV-58（12%）, HPV-33（8%） and HPV-6, HPV-11, HPV-18 and HPV-52 （6% each）. The concordance between HPV DNA and corresponding neutralizing antibodies was 56% （28/50） with a significant difference （P〈0.05）. The full-length sequences of five HPV types （HPV -42, -52, -53, -58 and -68） were determined and exhibited 98%-100% identities with their reported genomes. The present data may have utility for investigating the natural history of HPV infection and promote the development of HPV vaccines.

Using acoustic technique to detect leakage in city gas pipelines

For solving the difficult problem of leakage detection in city gas pipelines, a method using acoustic technique based on instantaneous energy (IE) distribution and correlation analysis was proposed. Firstly, the basic theory of leakage detection and location was introduced. Then the physical relationship between instantaneous energy and structural state variation of a system was analyzed theoretically. With HILBERT-HUANG transformation (HHT), the instantaneous energy distribution feature of an unstable acoustic signal was obtained. According to the relative contribution method of the instantaneous energy, the noise in signal was eliminated effectively. Furthermore, in order to judge the leakage, the typical characteristic of the instantaneous energy of signal in the input and output end was discussed using correlative analysis. A number of experiments were carried out to classify the leakage from normal operations, and the results show that the leakages are successfully detected and the average recognition rate reaches 93.3% among three group samples. It is shown that the method using acoustic technique with IED and correlative analysis is effective and it may be referred in other pipelines.

The Importance of Earnings Management Detection Models to Identify Fraud： A Case From Italian Listed Firms

Markets can get the confidence of investors enhancing the quality of governance and audit systems surrounding a firm. Financial reporting is a main component of them, being the basis for information necessary to investors＇ decisions. Managers have a chance to manipulate information provided in financial statements, in order to offer a better image of a firm to its potential and effective investors. The objective of this study is to evaluate the possibility of detecting extreme cases of earnings management and to check the predictive ability of the discretionary accruals models on the event of fraudulent earnings restatement. Through the abuse of reporting incentives, a manager gives out false information that should be averted and punished by regulators in a fair market system. The authors check the efficacy of different earnings management detection models in predicting discretionary manipulations and study the correlation between the frequency of manipulation and the event of fraud.

The weak form market efficiency investigation of American, European and Asian stock markets

This paper investigates the empirical validity of the Weak Form Efficient Market Hypothesis for American, European and Asian stock markets. Random Walk Hypothesis is used to prove weak form efficiency in American, European and Asian stock indices. ADF and PP Unit Root Tests have been used to test unit root in time series of daily data of American, European and Asian stock indices. Results show that sample of stock markets are weak-form efficient in terms of the Random Walk Hypothesis.

Analysis of the Bovespa Futures and Spot Indexes With High Frequency Data

Data from the World Federation of Exchanges show that Brazil＇s Sao Paulo stock exchange is one of the largest worldwide in terms of market value. Thus, the objective of this study is to obtain univariate and bivariate forecasting models based on intraday data from the futures and spot markets of the BOVESPA index. The interest is to verify if there exist arbitrage opportunities in Brazilian financial market. To this end, three econometric forecasting models were built： ARFIMA, vector autoregressive （VAR）, and vector error correction （VEC）. Furthermore, it presents the results of a Granger causality test for the aforementioned series. This type of study shows that it is important to identify arbitrage opportunities in financial markets and, in particular, in the application of these models on data of this nature. In terms of the forecasts made with these models, VEC showed better results. The causality test shows that futures BOVESPA index Granger causes spot BOVESPA index. This result may indicate arbitrage opportunities in Brazil.

一起不典型症状宋内志贺菌暴发疫情的实验室诊断

目的分析本实验室对1起由宋内志贺菌引起的不典型临床症状、疑似不明原因发热暴发疫情的实验室检测过程,为类似事件的实验室诊断提供参考。探讨通过增菌前后Ct值变化,荧光PCR用作病原菌确诊方法的可能性。方法采用总大肠菌群酶底物法测定总大肠菌群和大肠埃希菌,常规培养法和荧光PCR法测定患者咽拭和肛拭样品以及水样中病原微生物,用MIC法对分离菌株进行体外药敏试验。结果 10份饮用水中6份总大肠菌群和大肠埃希菌,不符合GB5749-2006的要求。常规培养9份肛拭均检出宋内志贺菌,而10份水样均未检出肠道致病菌。荧光PCR结果 9份肛拭和5份水样检出志贺菌核酸,5份水样增菌后Ct值较增菌前有明显下降。肛拭中分离的9株菌对青霉素类抗生素中的阿莫西林、哌拉西林、替卡西林100%耐药,对磺胺类、β-内酰胺类、头孢菌素类(1-4代)、氨基糖苷类等存在不同程度耐药。结论实验室应用指标菌检测、常规培养和荧光PCR技术,48 h即找到引起疫情暴发的原因,为疫情的控制提供了及时科学的依据。药敏试验为患者治疗提供了正确的药物选择依据。