Computational statistics for cell survival curves. I. Evaluation of the colony-forming ability of a single cell strain by the APL function CFALINE

An interactive program for the statistical analysis of cell survival curves by a linear regression approach is described. It allows for the computational determination of the linear part of a cell survival curve and the determination of a common slope estimate in the presence of repeated experiments for a particular cell strain with the appropriate variance estimates and confidence intervals.     

Job satisfaction and job survival.

Using a job satisfaction questionnaire constructed on previous samples, mail questionnaires were sent to 2,710 insurance agents, of whom 990 made a return. From these, matched samples of 99 survivors and 99 terminated agents were compared. The results "indicated that certain attitudes held by agents are significantly related to the criterion of survival-termination. It was also found that the proportion of agents expressing dissatisfaction with a particular item was not related to whether or not that item was predictive of the criterion. The data show that the validation of signed job satisfaction questionnaires leads to a much different kind of interpretation of the responses than is obtained from anonymous questionnaires." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Survival analysis applied to genetic evaluation for female fertility in dairy cattle

The objective of this research was to study whether survival analysis results in a more accurate genetic evaluation for female fertility traits compared with the usual methodology based on linear models. The fertility trait studied was interval between calving and last insemination. A stochastic simulation describing the reproductive cycle of first-parity cows was done, in which true breeding values for conception rate were created. A model containing effects of sire and herd was used both with survival analysis and with mixed linear model analysis to predict sire breeding values. Correlations between true breeding values for conception rate and breeding values for calving to last insemination predicted by the best survival analysis model or the best linear model were 0.77 and 0.68, respectively. The results showed that when pregnancy status is known, survival analysis is a better method than linear models for genetic evaluation of conception rate when using observations on the interval between calving and last insemination.     

Modelling of Cellular Survival Following Chromosome Aberration

In order to assess the biological effectiveness of protons and heavy ions, a mechanistic model of cellular survival following radiation-induced chromosome aberrations was proposed. DNA damage repair module of nanodosimetry biophysical Monte Carlo simulation code (NASIC) was developed to simulate chromosome aberrations in nucleus induced by different types of particles at different linear densities of energy transfer (LET). Based on the analysis of radiation-induced chromosome aberration, a mechanistic model of cellular survival following radiation-induced chromosome aberrations was proposed. The parameters of the model could be obtained by fitting the experimental data of cell survival curves. For V79 cells exposed to X-rays and protons at different LET, the cell survivals calculated with the proposed model are in good agreement with the experimental data, and the correlation coefficient is 0.985 3. The proposed model was validated by experimental data of V79 cells exposed to ⁴He ions and the correlation coefficient of the cell survival calculated with the proposed model, and the experimental data is 0.931 1. The results show that the proposed model can distinguish the difference of cell survival for cells exposed to different types of particles at different LET.     

浅谈道路绿化工程的施工与管理

结合漕俞路绿化工程,从施工前准备、施工中质量控制、种植后养护管理以及施工过程安全措施等几个方面探讨了道路工程的施工管理,以提高道路绿化施工质量,营造出令市民满意、舒适而优美的道路景观工程。     

猪肉中小肠结肠炎耶尔森菌失活/存活预测模型及控制研究

目的:建立小肠结肠炎耶尔森菌在猪肉中的存活/失活预测模型,并提出其控制措施。方法:用浓度梯度稀释法计细菌总量,按对数法作出不同条件下小肠结肠炎耶尔森菌的生长曲线。采用预测微生物学的基本方法和程序,并用CurveExpert1.38软件作为辅助工具,对试验数据进行拟合。结果:50℃、-18℃及速冻条件下该菌的初始菌数与时间为T时的菌数之比关于时间T的存活/失活预测模型符合Linear关系式,分别为Log(No/Nt)=1.0477287+0.1705726T,Log(No/Nt)=0.091057233+0.036013901T,LogNt=-0.0651058+0.97683871LogNo。结论:实验表明,本菌对高温非常敏感,在冷冻,速冻过程中仍能存活。     

Modelling the survival of starter lactic acid bacteria and Bifidobacterium bifidum in single and simultaneous cultures

The inactivation kinetics at 4 degrees C of Bifidobacterium bifidum, Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, cultured alone or consociated in a laboratory medium (modified MRS broth), were modelled through the Weibull model and a second-order polynomial equation. The initial cell number of S. thermophilus and L. delbrueckii subsp. bulgaricus was approximately 6-7log (CFU/ml); the viability loss after 30 days of storage was 2.87 and 1.99log (CFU/l) for L. delbruckii subsp. bulgaricus and S. thermophilus, cultured alone, respectively; whereas the consociation of lactobacilli and streptococci with bifidobacteria reduced viability loss during storage (0.28 and 0.54log CFU/l for lactobacilli and streptococci, respectively). Finally, the consociation of lactobacilli and streptococci with B. bifidum improved their oxygen uptake.     

Performance-based modelling of long-term deterioration to support rehabilitation and investment decisions in drinking water distribution systems

Managing the urban drinking water system in the long term in order to maintain system performance can be challenging due to the difficulty of modelling future deterioration of the networks. This paper establishes a methodology for cohort survival models where historical (empirical) data on decommissioning ages of pipes are used to calibrate survival functions of pipe cohorts according to service level targets. The benefit of the approach is that remaining useful life of pipes, future renewal rates and investment needs can be governed by a required level of service in the network. A case study shows how the methodology can be applied to a cohort of drinking water pipes to create a ‘calibration curve’, which is a survival function calibrated with empirical data.     

浅谈瓦斯抽采与曲江、尚庄两矿的生存与发展

在当前煤炭行业大环境下,曲江、尚庄两矿只有进行创新改革才有发展出路。改进瓦斯抽采工艺是实现生产效率、经济效益双提高的根本途径,是实现煤矿安全高效发展的必然要求。