A Theory for the Mortality Curve of Filament Lamps

We demonstrate for the first time that the ejection of tungsten atoms from a hot filament can be modeled by a binomial distribution. The relevant ejection chance per atom may have an arbitrary temporal profile depending on the presence of uniform Richardson evaporation, hot spots and temperature variation along the wire. A normal approximation is made and the lamp is supposed to fail if the undecayed atomic fraction drops below a critical value. The resulting formula for the lamp’s survival probability in terms of error function has one free parameter and is shown to be in excellent agreement with the experimental mortality curve.     

乳酸乳球菌乳脂亚种冷冻干燥保护剂优化及其贮藏稳定性

采用单因素试验、Plackett-Burman试验设计和Box-Behnken响应面法,筛选和优化乳酸乳球菌乳脂亚种KLDS4.0326真空冷冻干燥保护剂工艺,并分析冻干菌粉在不同温度下的贮藏稳定性。结果表明：脱脂乳粉、海藻糖和甘油含量是影响菌体细胞存活率的关键因素;以菌体细胞存活率为响应值,对3 个因素进行优化分析,保护剂最佳配比为：脱脂乳粉10.77 g/100 mL、海藻糖7.81 g/100 mL、甘油3.31 g/100 mL,此条件下菌体细胞存活率为（87.43±1.62）%,与理论预测值接近。在4 ℃和25 ℃条件下保藏12 个月后,菌体细胞存活率分别为40.63%和8.67%,冻干菌粉在4 ℃条件下具有更高贮藏稳定性。     

改进粒子滤波在汽轮机故障诊断中的应用

针对汽轮机的振动信号容易受到较为复杂的随机噪声污染,提出了一种改进粒子滤波的振动信号降噪方法;首先建立采集振动信号的数学模型,将其作为粒子滤波的状态方程;然后利用小波分析提取采集振动信号的背景噪声,将其和状态信号一起作为观测信号,得到观测方程,把降噪问题转化成在状态空间模型下的滤波问题;由于采用序贯重要性采样的粒子滤波存在着样本退化问题,在重采样阶段采用了一种权值排序、优胜劣汰的重采样算法,就是对各粒子的归一化权值从小到大的排列顺序,并根据权值方差大小淘汰粒子,从而得到了改进的粒子滤波算法,在一定程度上解决了标准粒子滤波的退化问题;进而运用改进粒子滤波算法对振动信号进行降噪处理,降噪前信号和降噪后信号分别通过小波包分解系数求取频带能量,根据各个频带能量的变化提取故障特征向量浓缩了汽轮机振动故障的全部信息,对提取的故障特征向量应用诊断识别算法进行故障模式识别;通过对比降噪前信号和降噪后信号的故障诊断识别率,证明了改进粒子滤波在汽轮机故障诊断中的应用效果更佳。     

大肠杆菌在茶叶中的存活及相关抑制效应的研究

本文对大肠杆菌在红茶、绿茶和乌龙茶中不同时间的存活率进行了研究。结果表明,不同品种的茶叶对大肠杆菌的抑制效应有显著差异。大肠杆菌在红茶中的存活时间最短,为36h,在乌龙茶中存活的时间最长,为144h。对多批茶叶生产过程中污染的大肠杆菌,24h后跟踪检测,其结果证实了红茶和绿茶对大肠杆菌显著的抑制效应。对茶叶抑制大肠杆菌作用机理进行了探讨,为当前控制茶叶中大肠杆菌的污染问题提出了新的证据和启示。     

‘To Go Beyond or Not to Be’ Unsolicited Architecture: An Interview with Ole Bourman

The complex dynamics of today's architecture require a deep intellectual freedom. This is something that Dutch architectural critic Ole Bouman espouses through his provocative writings and lectures and his advocacy of ‘unsolicited architecture’. Luca Guido invited Bouman to reflect on what it means to be an architect today and how it might be possible to pursue critical practice beyond the conventional construction processes. Copyright © 2009 John Wiley & Sons, Ltd.     

Spaces of Freedom

The predicaments of the current global climate bring a new poignancy and focus to architecture. Emiliano Gandolfi , the curator of the much lauded ‘Experimental Architecture’ exhibition in the Padiglione Italia at the 2008 Venice Biennale, outlines how an emerging group of designers are redefining architecture as they seek to provide solutions that identify people's needs and address the exigencies of global warning, the environmental crisis and migration. Copyright © 2009 John Wiley & Sons, Ltd.     

The association between foot lesions and culling risk in Ontario Holstein cows

The objective was to determine the association between specific foot lesions and culling in dairy cows. Using 5 trained professional hoof trimmers, data from 6,513 cows in 157 herds were recorded for analysis. During the study period, 1,293 cows (19.9%) were culled. Infectious lesions were most frequent in nonculled cows, whereas hoof horn lesions were most common in the culled cows. Median time to culling was 188 d [95% confidence interval (CI): 175-198 d] for cows without a lesion and 157 d (CI: 149-168 d) for cows with a lesion. Time from hoof trimming to culling was used to model the association between foot lesions and culling hazard. The final multivariate Cox proportional hazards model included heifers, infectious lesions, white line lesions, hemorrhages, sole ulcers, other lesions, and free-stall housing as covariates. Results of the final model showed that infectious hoof lesions had no significant association with culling. Yet, the hazard ratios for white line lesions, ulcers, and hemorrhage were 1.72 (CI: 1.39−2.11), 1.26 (CI: 1.05−1.52), and 1.36 (CI: 1.16−1.59), respectively. The association with culling for the grouped variable “other lesions” was time dependent and decreased with time. These results illustrate that there were significant associations with cow productivity for hoof horn lesions found at routine hoof trimming and that emphasis should be placed on proper treatment and earlier detection of these foot lesions.     

Modeling microbial populations with the original and modified versions of the continuous and discrete logistic equations

The life histories of microbial populations, under favorable and adverse conditions, exhibit a variety of growth, decay, and fluctuation patterns. They have been described by numerous mathematical models that varies considerably in structure and number of constants. The continuous logistic equation alone and combined with itself or with its mirror image, the Fermi function, can produce many of the observed growth patterns. They include those that are traditionally described by the Gompertz equation and peaked curves, with the peak being symmetric or asymmetric narrow or wide. The shape of survival and dose response curves appears to be determined by the distribution of the resistance's to the lethal agent among the individual organisms. Thus, exponential decay and Fermian or Gompertz‐type curves can be considered manifestations of skewed to the right, symmetric, and skewed to the left distributions, respectively.

Because of the mathematical constraints and determinism, the original discrete logistic equation can rarely be an adequate model of real microbial populations. However, by making its proportionality constant a normal‐random variate it can simulate realistic histories of fluctuating microbial populations, including scenarios of aperiodic population explosions of varying intensities of the kind found in food‐poisoning episodes.     

The red flour beetle Tribolium castaneum allows for the convenient determination of fitness and survival as a measure of toxic effects of the food contaminant acrylamide

Acrylamide is a toxic ingredient generated as a by-product of the Maillard reaction in starchy foods processed at temperatures above 120°C. Here we used the red flour beetle Tribolium castaneum as a model organism to test the effects of acrylamide on fitness and survival. Beetles were fed on flour spiked with acrylamide between 0.5% and 10% at 32°C over 2 weeks. Fitness of the beetles was tested by measuring the running distance and survival was recorded after 2 weeks of feeding at increased temperatures at 42°C. Both parameters were dose-dependent reduced by acrylamide. Knockdown of gene homologues of ahr, the arylhydrocarbon receptor, and of nrf-2, the nuclear factor erythroid 2-related factor 2, both reduced fitness and survival. Application of 0.5% acrylamide under knockdown of each factor further reduced fitness and survival, suggesting that ahr and nrf-2 are important for an adequate response to the toxicant. RNA-interference for ahr blocked completely the increase in nrf-2 mRNA levels, suggesting that the actions of ahr on acrylamide detoxification are mediated via Nrf-2.