Dynamic survival analysis for non-Markovian epidemic models

We present a new method for analysing stochastic epidemic models under minimal assumptions. The method, dubbed dynamic survival analysis (DSA), is based on a simple yet powerful observation, namely that population-level mean-field trajectories described by a system of partial differential equations may also approximate individual-level times of infection and recovery. This idea gives rise to a certain non-Markovian agent-based model and provides an agent-level likelihood function for a random sample of infection and/or recovery times. Extensive numerical analyses on both synthetic and real epidemic data from foot-and-mouth disease in the UK (2001) and COVID-19 in India (2020) show good accuracy and confirm the method’s versatility in likelihood-based parameter estimation. The accompanying software package gives prospective users a practical tool for modelling, analysing and interpreting epidemic data with the help of the DSA approach.     

供电企业的生存环境及SWOT分析

通过优势分析、劣势分析机会分析、威胁分析方法,剖析供电企业的现状,提出解决困难的思路。     

WSN巡逻式强栅栏调度算法研究

无线传感器网络栅栏覆盖研究已取得丰厚成果.提出一种巡逻式栅栏调度算法,该算法将栅栏均匀分为若干子栅栏,依次轮流激活子栅栏,激活的子栅栏工作一段时间后进入休眠状态,然后下一条子栅栏由休眠进入激活状态.因此子栅栏的轮流激活形成了栅栏的巡逻状态,当入侵者穿越栅栏时有很大概率会被巡逻子栅栏检测到.在确保栅栏检测率的情况下使得栅栏的生存时间得到大幅度延长.文中计算了在理论情况下的栅栏检测率,最后通过实验验证了该算法的准确性和可靠性.     

Impact of glycated pea proteins on the activity of free‐swimming and immobilised bacteria

BACKGROUND: Glycation (non‐enzymatic glycosylation), a spontaneously occurring process, is responsible for alteration of the structures and biological activities of proteins, making them highly active. Regrettably, information regarding the impact of glycated food proteins on intestinal bacteria still remains sparse. Pea seeds are considered to be a biological material of a high nutritional value, low content of anti‐nutritional substances and proven health‐promoting action and therefore they were used in this study. Since glycated pea proteins are proven to display a lowered susceptibility to the enzymatic digestion, their impact on the activity of both free‐swimming and immobilised bacteria was studied. RESULTS: In vitro model systems were used to prove the stimulatory impact of glycated pea proteins on the proliferation rate and survival, as well as on the metabolic activity of free‐swimming and immobilised bacteria. CONCLUSIONS: This phenomenon is of great importance because glycated food proteins are not only a source of nutrients and energy but also display new properties and increased biological activities. Additionally, they are able to modify the bacterial intestinal ecosystem, thus affecting the general health status of a consumer. Copyright © 2010 Society of Chemical Industry     

Short communication: Effect of freezer storage time and thawing method on the recovery of Mycoplasma bovis from bovine colostrum

Mycoplasma bovis is an important cause of mastitis in dairy cattle, and pneumonia, arthritis, and otitis in calves. Milk and colostrum are considered important sources of infection for calves. knowledge on the effect of on-farm freezing (?18°C) and thawing methods on the recovery of M. bovis from colostrum samples is missing. In this study, 2 separate experiments were performed. The first experiment consisted of a longitudinal study examining the survival [as measured by log(10) reduction] of 2 M. bovis strains in frozen colostrum over 14 wk. The second experiment examined the effect of different thawing temperatures (45 and 20°C), thawing frequencies (once or twice), and initial colostrum titer (10⁴ or 10⁶ cfu/mL) on M. bovis survival. A single freeze-thaw cycle led to an approximate 1 log reduction of M. bovis titer, independent of the thawing temperature. Freezing for 14 wk did not significantly further reduce the titer of bacteria compared with freezing for 2 wk. A second freeze-thaw cycle further reduced the M. bovis count by approximately 0.5 log compared with a single freeze-thaw cycle. Thawing temperature and initial bacterial concentration did not significantly affect M. bovis reduction. In conclusion, storage of colostrum samples in the freezer at ?18°C during epidemiological studies, herd monitoring, or test and cull programs will probably have little influence on qualitative bacteriological test results for M. bovis. The epidemiological or clinical relevance of an approximate 1 log reduction of M. bovis in colostrum is currently unclear.     

抗冻酵母的筛选及发酵特性研究

采用模拟面团预发酵法筛选出应用于冷冻面团的菌株,研究菌株胞内化合物含量与其抗冷冻能力、相对发酵力的相关性,并且根据菌株菌落形态和26SrDNA序列分析法鉴定抗冻性能或发酵性能优良的菌株。结果表明,4个样品中筛选了7株酵母菌,存活率为9%~86%,相对发酵力为9%~67%,其中菌株Y-3的存活率较高,达到86%,菌株H-1的相对发酵力最高,达到67%。相关性分析结果表明,细胞存活率与海藻糖含量、甘油、脯氨酸含量呈正相关,与精氨酸、天冬氨酸、谷氨酸及相对发酵力呈负相关;相对发酵力与天冬氨酸、谷氨酸含量呈显著正相关,与海藻糖、甘油、脯氨酸、精氨酸呈负相关。菌株鉴定结果表明,菌株Y-3为汉逊德巴利酵母(Debaryomyces hansenii),菌株H-1为酿酒酵母(Saccharomyces cerevisiae)。综合抗冷冻性能、发酵力和食用安全性,后续研究拟将菌株Y-3和H-1进行混合发酵,最终应用于冷冻面团的制作。     

A deep learning approach for predicting critical events using event logs

Event logs, comprising data on the occurrence of different types of events and associated times, are commonly collected during the operation of modern industrial machines and systems. It is widely believed that the rich information embedded in event logs can be used to predict the occurrence of critical events. In this paper, we propose a recurrent neural network model using time-to-event data from event logs not only to predict the time of the occurrence of a target event of interest, but also to interpret, from the trained model, significant events leading to the target event. To improve the performance of our model, sampling techniques and methods dealing with the censored data are utilized. The proposed model is tested on both simulated data and real-world datasets. Through these comparison studies, we show that the deep learning approach can often achieve better prediction performance than the traditional statistical model, such as, the Cox proportional hazard model. The real-world case study also shows that the model interpretation algorithm proposed in this work can reveal the underlying physical relationship among events.     

凸性数据的样条修匀及其应用

借助于样条技术 ,给出了利用先验信息对初始估计进行修正的新方法 .这些先验信息可以包含数据的凸性以及增减性 .同时讨论了这种数据处理方法在生存分析尤其是精算等领域中的应用 .     

Survival in food systems of Lactobacillus rhamnosus R011 microentrapped in whey protein gel particles

ABSTRACT:  The aim of this study was to investigate the effect of whey protein isolate (WPI) gel microentrapment on the viability of Lactobacillus rhamnosus R011 during the production and storage of biscuits, frozen cranberry juice, and vegetable juice. Viability of microentrapped (ME) cells was compared to free cells freeze-dried in a milk-based protective solution as well as in a WPI-based solution (ungelled). During the production of biscuits and their storage for 2 wk at 23 °C, the highest stability was obtained with the cells ME in WPI gel particles. However, free cells prepared in the milk-based matrix were those that maintained the highest viability during storage of vegetable juice as well as during freezing and storage of cranberry juice. The culture prepared in a WPI-based solution had the highest drops in viable counts following the heating process of biscuits as well as during storage of vegetable juice and freezing and storage of cranberry juice. Although the WPI-based solution was not efficient in protecting free cells, it is concluded that the process of microentrapment in WPI can help in protecting the freeze-dried cells against subsequent acidic and alkaline pH conditions as well as heating and freezing of food products.