Assessment of the colorimetric and fluorometric assays for alkaline phosphatase activity in cow's, goat's, and sheep's milk

Raw milk is a well-established vehicle for the carriage of human pathogens, and many regulatory bodies have consequently mandated compulsory pasteurization as a food safety intervention. The residual activity of alkaline phosphatase (ALP) has historically been used to verify the adequacy of pasteurization of cow's milk. However, there is uncertainty on how the current ALP standards and methods of analysis can be applied to sheep's and goat's milk, which naturally contain different levels of the enzyme than that found in cow's milk. The official ALP methods applied in Canada (colorimetric assay; MFO-3) and in the United States (Fluorophos) were assessed for their ability to detect enzyme activity in raw and pasteurized milk derived from cows, sheep, and goats. The detection limit and the limit of quantitation were 0.8 and 2.02 microg/ml phenol, respectively, for the MFO-3 method and 43 and 85 mU/liter, respectively, for the Fluorophos method. The average ALP levels in raw goat's, cow's, and sheep's milk were 165, 1,562, and 3,512 microg/ml phenol, respectively. Raw milk detection limits, which correspond to raw milk phosphatase levels, were 0.051, 0.485, and 0.023% in cow's, goat's, and sheep's milk, respectively, for the MFO-3 method and 0.007, 0.070, and 0.004%, respectively, for the Fluorophos method. Although both methods can be used for ALP determination in cow's, goat's, and sheep's milk, the Fluorophos assay was superior to the colorimetric MFO-3 method based on sensitivity and time required to complete the analysis.     

Fracture behaviour of thermosetting polymers for ophthalmic lenses

In the worldwide market we found strongly positioned two thermosetting materials for ophthalmic lenses: CR-39 and Superfin. In this work, the fracture behaviour of both materials is studied through the application of Linear Elastic Fracture Mechanics (LEFM) using two geometries: double torsion and three point bending. The fracture toughness has been determined by the double torsion technique. CR-39 showed a continuous and stable crack propagation, whereas Superfin exhibited a stick-slip behaviour whose instability decreased when the strain rate increased. The values at crack initiation agreed with the fracture toughness results of single edge notched tests in bending geometry.     

Optimal control of demand-paging systems

Demand-paging systems are characterized as stochastic control processes, and optimal page replacement decisions are determined by means of dynamic programming. This approach is distinguished from others by its utilization of page structure information, which may be either supplied a priori or else dynamically learned. The main result is an optimal realizable solution for a general class of replacement problems. The resulting algorithm subsumes others (including “A₀”) as special cases.     

《德伯家的苔丝》叙事风格谈片

《德伯家的苔丝》是一部震撼人心的悲剧作品,其艺术成就人们多有论及。本文试从环境描写、细节安排方面略作如下研讨:优美的环境描写与惨痛的故事情节形成鲜明的反差,奇妙而和谐地达到统一,构成小说无与伦比的奇特魅力;环境描写成功地为刻画人物心理活动服务;在细节的处理上显示出作者独具匠心;《圣经》故事的引用,使得整部作品充满了浓烈的浪漫主义气息。     

Juice characteristics related to woolliness and ripening during postharvest storage of peaches

 The effect of up to three cycles of intermittent warming (IW) for one day at 20  °C every 6 days of storage at 0.5  °C on the development of woolliness and on the changes in juice characteristics during post-storage ripening of "Paraguayo" peaches at two ripening stages was studied. By subjecting the peaches to IW, woolliness was strongly reduced concomitantly with a sudden reduction in flesh firmness due to normal fruit ripening. During post-storage ripening, extractable juice and juiciness only decreased in conventionally stored (CS) fruit as a result of woolliness. However, the liquid phase of the juice extracted (clear juice) decreased in IW but not in woolly CS fruit. Clear juice reduction appeared to be related to normal advanced ripening, with differences between woolly and sound fruit associated with the ripening stage during storage. The technological and physiological implications of these quality indices, mainly related to ripening, senescence, and woolliness, are discussed. These results support the hypothesis that IW maintains cellular membrane integrity and helps the recovery of pectolytic enzymatic activity. It has been stated that the incidence of woolliness was more closely related to the juice release mechanism than to the clear juice content. Received: 30 April 1998 / Revised version: 1 July 1998     

Polynomials Irreducible by Eisenstein's Criterion

We compute the probability for a monic univariate integer polynomial to be irreducible by Eisenstein's Criterion. In particular, it follows that less than 1% of the polynomials with at least seven non-zero coefficients are irreducible by Eisenstein. Keywords:Irreducible polynomial, Eisenstein's Criterion.     

从工具走向新理论的信息设计

信息设计作为一种新生事物,倍受质疑:它扮演的仅仅是一种新工具,还是意味着一个新的设计理论的诞生。文中试图从工具和理论的衡量标准,即信息设计是否能够进行设计思考,是否引起或即将引起设计方法、设计过程、设计的形态空间理论的变革出发,揭示信息设计已不仅仅停留在设计工具阶段,正走向构建自己理论体系之路。     

网络与新媒体艺术

从分析网络与媒体技术入手,讨论了新媒体艺术与网络的关系,指出了网络新技术与新媒体艺术要互相促进才能求得共同发展。为推动新媒体艺术不断向前进步,需要艺术家、计算机程序员和网络工程师互相协作发挥各自的聪明才智。     

Optimal control of demand-paging systems

Demand-paging systems are characterized as stochastic control processes, and optimal page replacement decisions are determined by means of dynamic programming. This approach is distinguished from others by its utilization of page structure information, which may be either supplied a priori or else dynamically learned. The main result is an optimal realizable solution for a general class of replacement problems. The resulting algorithm subsumes others (including “A₀”) as special cases.     

Eye movements of young and older adults while reading with distraction.

The authors used eye-tracking technology to examine young and older adults' online performance in the reading in distraction paradigm. Participants read target sentences and answered comprehension questions following each sentence. In some sentences, single-word distracters were presented in either italic or red font. Distracters could be related or unrelated to the target text. Online measures, including probability of fixation, fixation duration, and number of fixations to distracting text, revealed no age differences in text processing. However, young adults did have an advantage over older adults in overall reading time and text comprehension. These results provide no support for an inhibition deficit account of age differences in the reading in distraction paradigm, but are consistent with J. Dywan and W. E. Murphy's (1996) suggestion that older adults are less able than the young to distinguish target and distracter information held in working memory. (PsycINFO Database Record (c) 2010 APA, all rights reserved)