Estimating the initial freezing point of foods from composition data

The initial freezing point of food was estimated from the mole fractions of individual solutes in the aqueous phase (ions, sugars, acids and alcohol), derivable from information given in nutritional tables. Predicted values were compared with experimental measurements taken from the literature. Predicted and experimental values generally agreed to within 1 °C, despite the solute concentrations of the measured foods being assumed to be those of the average compositions given in nutritional tables. The effects of the addition of salt to meat and of dehydration of various foods on freezing point depression, and the effect of temperature on the ice content of frozen foods were also successfully predicted.     

单一型聚醚改性有机硅消泡剂的研制

研制了一种不添加助剂的聚醚改性有机硅消泡剂，考察了反应温度以及催化剂用量对接枝反应的影响，得出了较为合理的实验条件；重点研究了泉硅氧烷结构（含氢量和分子质量）对接枝反应及消泡剂浊点的影响．     

Estimating microbial growth parameters from non-isothermal data: a case study with Clostridium perfringens

Microbial growth parameters are usually calculated from the fit of a growth model to a set of isothermal growth data gathered at several temperatures. In principle at least, it is also possible to derive them from non-isothermal ('dynamic') growth data. This requires the numerical solution of a rate model whose coefficients are nested terms that include the temperature profile. The methodology is demonstrated with simulated non-isothermal growth data on which random noise had been superimposed to emulate the scatter found in experimental microbial counts. The procedure has been validated by successful retrieval of the known generation parameters from the simulated growth curves. The method was then applied to experimental non-isothermal growth data of C. perfringens cells in cooled ground beef. The growth data collected under one cooling regime were used to predict the organism's growth patterns under different temperature histories. The practicality of the method is currently limited because of the relatively large scatter found in experimental microbial growth data and the relatively low frequency at which they are collected. But if and when the scatter could be reduced and the counts taken at short time intervals, the method could be used to determine the growth model in situ thus enabling to translate the changing temperature during processing, transportation or storage into a corresponding growth curve of the organism in question.     

Estimating microbial survival parameters from dynamic survival data using Microsoft Excel

Reliable survival parameter estimation is an essential part of building predictive models for microbial survival. It has been demonstrated that these parameters can be accurately identified using a one‐step regression approach that fits a survival model to multiple dynamic data sets at once. However, the existing methods are not quite user‐friendly because their application requires relatively high computer skills. In this study, a recursive equation for the Weibull model was used to construct microbial survival curves under dynamic conditions. Based on this, a procedure was developed to estimate survival parameters by fitting the equation to dynamic survival data sets using the built‐in functions and Solver of Microsoft Excel. The results showed that the method provided an easy and accurate way for estimating microbial survival parameters.     

Estimating bacterial density from tube dilution data by a Bayesian method

We have developed a statistical computer program based on a Bayesian approach to estimate bacterial density from tube dilution data. The program calculates an expectation, a mode (equivalent to the traditional most probable number (MPN)) and a median as point estimates of the bacterial density. The Bayesian analysis provides a probability density function which reflects the knowledge accumulated about the bacterial density by observing the data. Its expectation is a summary value that incorporates the shape and skewness of the distribution. On the other hand, the MPN (mode) only uses the single most likely value and ignores other values that are consistent with the data. As a result the MPN consistently underestimates the bacterial density and is likely to produce large errors. Thus we recommend the use of the expectation as an estimator for most problems. The theoretical basis of the Bayesian approach and its application toSalmonelladata is discussed. Tables of results for different combinations of tube dilutions are also presented.     

Quantification of variability and uncertainty for air toxic emission inventories with censored emission factor data

Probabilistic emission inventories were developed for urban air toxic emissions of benzene, formaldehyde, chromium, and arsenic for the example of Houston. Variability and uncertainty in emission factors were quantified for 71-97% of total emissions, depending upon the pollutant and data availability. Parametric distributions for interunit variability were fit using maximum likelihood estimation (MLE), and uncertainty in mean emission factors was estimated using parametric bootstrap simulation. For data sets containing one or more nondetected values, empirical bootstrap simulation was used to randomly sample detection limits for nondetected values and observations for sample values, and parametric distributions for variability were fit using MLE estimators for censored data. The goodness-of-fit for censored data was evaluated by comparison of cumulative distributions of bootstrap confidence intervals and empirical data. The emission inventory 95% uncertainty ranges are as small as -25% to +42% for chromium to as large as -75% to +224% for arsenic with correlated surrogates. Uncertainty was dominated by only a few source categories. Recommendations are made for future improvements to the analysis.     

Analysis of censored data for such as colostral immunoglobulin transfer in calves.

Passive immunity in the neonatal calf is dependent upon colostral immunoglobulin transfer into the systemic circulation. Critical in this transfer is the period of absorption, which is dependent upon age of initial feeding of the calf and amount fed. For some calves known only was that absorption extended beyond duration of the experiment, causing the data to be censored. Analysis of the length of absorption showed a two-phase regression model when censored data were used with uncensored data. Incorrect inferences may be drawn if censored data are not incorporated into the analysis.     

Hierarchical Bayesian analysis of censored microbiological contamination data for use in risk assessment and mitigation

Microbiological contamination data often is censored because of the presence of non-detects or because measurement outcomes are known only to be smaller than, greater than, or between certain boundary values imposed by the laboratory procedures. Therefore, it is not straightforward to fit distributions that summarize contamination data for use in quantitative microbiological risk assessment, especially when variability and uncertainty are to be characterized separately. In this paper, distributions are fit using Bayesian analysis, and results are compared to results obtained with a methodology based on maximum likelihood estimation and the non-parametric bootstrap method. The Bayesian model is also extended hierarchically to estimate the effects of the individual elements of a covariate such as, for example, on a national level, the food processing company where the analyzed food samples were processed, or, on an international level, the geographical origin of contamination data. Including this extra information allows a risk assessor to differentiate between several scenario’s and increase the specificity of the estimate of risk of illness, or compare different scenario’s to each other. Furthermore, inference is made on the predictive importance of several different covariates while taking into account uncertainty, allowing to indicate which covariates are influential factors determining contamination.     

我国甜菜糖相关数据统计分析

以SPSS和Excel软件对世界及我国甜菜糖相关数据——甜菜种植面积、单产、总产、产糖量和食糖消费量等进行作图、统计、分析，寻找其规律性，为我国糖业尤其是甜菜糖业的发展提供依据或参考。     

Analysis of fertility and dystocia in Holsteins using recursive models to handle censored and categorical data

A method based on the analysis of recursive multiple-trait models was used to 1) estimate genetic and phenotypic relationships of calving ease (CE) with fertility traits and 2) analyze whether dystocia negatively affects reproductive performance in the next reproductive cycle. Data were collected from 1995 through 2002, and contained 33,532 records of CE and reproductive data of 17,558 Holstein cows distributed across 560 herds in official milk recording from the Basque Country Autonomous Community (Spain). The following fertility traits were considered: days open (DO), days to first service, number of services per pregnancy (NINS), and outcome of first insemination (OFI). Four bivariate sire and sire-maternal grandsire models were used for the analyses. Censoring existed in DO (26.49% of the data) and NINS (12.22% of the data) because of cows having been sold or culled before reaching the next parturition. To avoid bias, a data augmentation technique was applied to censored data. Threshold models were used for CE and OFI. To consider that CE affects fertility and the genetic determination of CE and fertility traits, recursive models were applied, which simultaneously considered CE as a fixed effect on fertility performance and the existence of a genetic correlation between CE and fertility traits. The effects of CE score 3 (difficult birth) with respect to score 1 (no problem) for days to first service, DO, NINS, and OFI were 8 d, 31 d, 0.5 services, and - 12% success at first insemination, respectively. These results showed poorer fertility after dystocia. Genetic correlations between genetic effects of fertility traits and CE were close to zero, except for the genetic correlations between direct effects of DO and CE, which were positive, moderate, and statistically different from 0 (0.47 ± 0.24), showing that genes associated with difficult births also reduce reproductive success.     

芹菜中黄酮类化合物及其生物活性研究进展

芹菜是一种常见的蔬菜,在我国分布广泛。通常含有多种黄酮类物质,包括芹菜素及其糖苷、槲皮素、山奈酚、木犀草素等。本文综述了芹菜中的总黄酮含量与品种,取样部位,生长期等因素的关系。在生物活性方面,芹菜黄酮具有抗氧化、抗癌、抵抗心血管疾病功效,在生殖系统方面有抑制雌激素和孕激素分泌等作用。      

协变量Ⅰ型截尾时线性模型的非参数估计

对截断变量适当修正后,给出了协变量Ⅰ型截尾时期望的无偏估计.并证明了其方差在一定条件下小于开窗法得到的方差,从而提高了线型模型参数的估计精度.     

Genetic evaluation for length of productive life with censored records.

This study was conducted to investigate the impact of censoring on the accuracy of sire evaluation for the length of productive life estimated by means of survival analysis using simulated and real dairy cattle data from the Swiss Braunvieh population. Data were simulated under a Weibull model with two fixed effects and a random sire effect with a sire variance of 0.04. Two different family structures investigated were 1000 sires with 10 daughters each and 200 sires with 50 daughters each. Sires were assumed to be related through their sires. The reference data were generated assuming no censoring. Sire effects were estimated from the reference data with and without considering the relationships among sires and referred to as the estimated transmitting abilities (ETA) of sires. The impact of censoring on accuracy of ETA and ranking of sires was investigated by computing rank correlations among true and estimated sire effects and among estimated sire effects from the reference data and from several different data files with increased proportion of censored records. Estimated transmitting abilities were generally more accurate with a large number of daughters. The rank correlations among the ETA of sires from the data with censored records and the ETA from the reference data decreased with an increased proportion of censored records. Considering relationships among sires resulted in higher rank correlations when the proportion of censored records was large. With 50 daughters per sire, accuracy of 70% can be achieved approximately 2 yr after first calving of the daughters with about 50% censored records. With the real data, a rank correlation with the ETA of sires from the reference data of 0.70 to 0.80 can be achieved with about 65% of records censored and about 2.5 yr after the first calving of the youngest daughters of the sires.     

Genetic analyses of mastitis data using animal threshold models and genetic correlation with production traits

In the present study, 6 different mastitis data sets of 3 dairy herds with an overall herd size of 3200 German Holstein cows were analyzed. Data collection periods included the first 50, 100, or 300 d of lactation. The 3 data collection periods were analyzed with a lactation model and a test-day model. All models were animal threshold models. Mastitis frequencies in the lactation model data sets varied between 29 and 45%, and varied between 3 and 6% in the test-day model data sets. Depending on the period of data collection, heritabilities of liability to mastitis in the lactation models were 0.05 (50 d), 0.06 (100 d), and 0.07 (300 d). In the test-day models, heritabilities were slightly higher with values of 0.09 (50 and 100 d), and 0.06 (300 d). Between lactation models, the rank correlations between the relative breeding values were high and varied between 0.86 and 0.94. Rank correlations between the relative breeding values of the test-day models ranged from 0.68 to 0.87. The rank correlations between the relative breeding values of lactation models and test-day models varied from 0.51 and 0.80. Genetic correlations between mastitis and milk production traits were estimated with a linear animal test-day model. The correlations with mastitis were 0.29 (milk yield), 0.30 (fat yield), 0.20 (fat content), 0.34 (protein yield), and 0.20 (protein content). The estimated genetic correlation between mastitis and somatic cell score was 0.84.     

后整理剂的生态环保问题分析

纺织品后整理加工作为一个典型的化学处理过程，后整理刺中有一些品种有可能危及人体健康或破坏生态环境。文中概述了国际、国内生态纺织品标准，并对七大类后整理制进行生态评估．对已知晓化学结构并经安全性试验的后整理剂进行综合分析，指出了安全的后整理剂品种。七大类后整理剂包括：聚氨酯涂层剂、耐久压烫整理剂、柔软剂、阻燃剂、抗菌卫生整理剂、防蛀整理剂和防螨整理剂．     

The interpretation of rate curves arising from membrane permeation studies

The evaluation of rate curves arising from the permeation of salicylic acid through human and pig skin is discussed. The approaches based upon steady state and time lag analyses are commented on in comparison with a more complete mathematical model.
Some model zeolite/polystyrene membranes are also discussed.
Interprétation des courbes découlant d'études de perméabilité des membranes     

Pre-slaughter stress arising from on-farm handling and its interactions with electrical stimulation on tenderness of lambs

The effect of electrical stimulation of lamb carcasses (n=269) or its absence (n=257) on shear force of m. longissimus thoracis et lumborum (LT) was monitored during ageing in pasture-fed merino lambs (n=526). The lambs were slaughtered on four different days allowing durations of between one to 10 days of recovery from pre-slaughter handling (yarding, weighing and crutching) that affected ultimate pH (pH(u)). The right LT was removed 20-40min post-slaughter, tightly-wrapped in cling film (prevents the muscle cross-section increasing and thus minimising shortening) and rapidly cooled to 15°C to enter rigor mortis and age. At 0, 4, 24 and 72h post-slaughter, pH measurements and samples for shear force measurement were taken. Pre-slaughter handling had a significant negative effect on pH(u) and several days recovery were required for pH(u) to reach values associated with optimal meat quality as reflected by pH(u). Lambs with one and three days recovery (no significant difference between them) had a pH(u)>5.7 in 50% of the muscles and 19.4%>pH(u) 5.8. Whereas, in lambs with 8-10 days recovery (no significant difference between them), only 8% had a pH(u)>5.7 and 3.1%>pH(u) 5.8. Within each slaughter day electrically stimulated lambs were always more tender than non-stimulated lambs. For non-stimulated muscles at 72h, shear force values >40N occurred for 11.2% of the muscles: for electrically stimulated muscles at 72h, shear force values >40N occurred for 1.9% of the muscles. The rates of tenderisation were slower for intermediate pH(u) values resulting in higher shear force values at all ageing durations. With ageing at 72h for intermediate pH(u), non-stimulated muscles (n=38) 17.64% were >40N and for stimulated muscles (n=34), 7.9% were >40N.     

Estimating the health consequences of replacing cigarettes with nicotine inhalers

Background: A fast acting, clean nicotine delivery system might substantially displace cigarettes. Public health consequences would depend on the subsequent prevalence of nicotine use, hazards of delivery systems, and intrinsic hazards of nicotine.