Temporal shifts in the biodiversity of nearshore small fishes in Lake Simcoe

Nearshore small fish species represent a large proportion of fish biodiversity in Lake Simcoe, a large inland lake in southern Ontario, Canada. Over the past 30 years, Lake Simcoe has experienced several changes to its aquatic habitat, benthic invertebrate communities and predatory fish populations. This study compared samples of the nearshore small fish community in three geographic areas of Lake Simcoe. Fish community data were grouped into two time periods: a contemporary period (2007–2009) and a historical period (1982–1995). The fish community was compared across time periods for each area to assess if observed ecological changes had an impact on the small fish community. Species richness significantly declined between time periods in two areas (Cook's Bay and the southeast shoreline), the number of individuals captured declined between time periods in one area of the lake (Kempenfelt Bay) and Simpson's diversity index declined between time periods in one area of the lake (southeast shoreline). There were no significant differences in the Shannon–Weiner evenness index between time periods in any of the study areas. Additional analyses of intra- and inter-annual variation in fish sampling results generally supported the findings that shifts in the fish community occurred between time periods. Overall, this study suggests that the nearshore small fish biodiversity of Lake Simcoe has shifted over time but these shifts are not clearly related to recent increases in water clarity, macrophyte growth and nearshore benthic invertebrate densities.     

Developmental change in the acuity of the number sense: The approximate number system in 3-, 4-, 5-, and 6-year-olds and adults.

Behavioral, neuropsychological, and brain imaging research points to a dedicated system for processing number that is shared across development and across species. This foundational Approximate Number System (ANS) operates over multiple modalities, forming representations of the number of objects, sounds, or events in a scene. This system is imprecise and hence differs from exact counting. Evidence suggests that the resolution of the ANS, as specified by a Weber fraction, increases with age such that adults can discriminate numerosities that infants cannot. However, the Weber fraction has yet to be determined for participants of any age between 9 months and adulthood, leaving its developmental trajectory unclear. Here we identify the Weber fraction of the ANS in 3-, 4-, 5-, and 6-year-old children and in adults. We show that the resolution of this system continues to increase throughout childhood, with adultlike levels of acuity attained surprisingly late in development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Minimizing the number of late jobs for the permutation flowshop problem with secondary resources

This paper considers a permutation flowshop problem with secondary resources with the objective of minimizing the number of tardy jobs. The number of secondary resources assigned to the machines (workcenters), as well as the allocation of resources among the various machines, will play a significant role in the time required to process each job by its specified due date. This problem finds application in a large number of environments including manufacturing, maintenance, warehousing operations, as well as in healthcare. The research presents a lower bound for the permutation flowshop problem and evaluates its performance against the optimal solution for small, medium, and large instances. Several heuristics, including neighborhood search and simulated annealing, are presented to generate the secondary resource assignment and the allocation of jobs to the schedule. The computational complexity of the lower bound and computational examples for the heuristics are discussed.     

民用运输机场飞行区消防给水管道选用要点分析

当前飞行区消防给水管道选材无相应的标准,影响飞行区消防给水管道选用因素较多,管道渗漏所造成的损失(尚不包括机场运营第三方损失)远远大于材料本身。结合相关机场工程实例,通过对飞行区常用消防管道的基本材料性能、公称压力、埋深、管道连接与补偿及管道单位造价的对比分析,提出管道的安全性(结构强度与低渗漏性)是设计人员应该考虑的第一要素,单位管长管道接口数是衡量管道安全性的重要指标。选择成熟稳定质量的管道(并提出原料性能限制)及连接方式,降低单位管长管道接口数,并做好管道补偿设计,对于飞行区消防给水管道防渗漏及耐压力波动、耐不均匀沉降、耐管道轴向位移等方面具有重要的意义。     

有机添加剂对模拟油EACN值及动态界面张力的影响

本文通过改变两种石油磺酸盐的混合比例,配制出碳数最低值不同的一系列混合表面活性剂溶液作为标尺,考察了几种有机酸、十八醇、Ｓｐａｎ６０ 及两种卟啉（ ＯＥＰ和ＥＴＩＯ） 对正癸烷模拟油的ＥＡＣＮ 值及油水界面张力的影响。     

柴油-甲醇乳化燃料乳化剂的最佳HLB值及水含量的影响

柴油机中掺烧醇的最大难点之一在于难以获得价廉、稳定的柴油-甲醇乳化燃料。作者研究了柴油-甲醇乳化燃料乳化剂的最佳HLB值以及不同含水量对最佳HLB值的影响。研究结果表明：柴油-甲醇乳化燃料乳化剂的最佳HLB值在3．5左右,当柴油甲醇乳化燃料中含水形成了甲醇-水-柴油三元乳化燃料时,其最佳HLB值与柴油-水的最佳HLB值相同,且三元乳化燃料乳化剂的最佳HLB值不随含水量的增加而变化,但随着含水量增加,乳化燃料分层时间会产生变化;在柴油-甲醇-水乳化液中,当水在甲醇-水混合液中的比例为40％左右时,甲醇-水-柴油三元乳化燃料(柴油：甲醇 水=8：1)的分层时问最长,即在柴油-甲醇乳化燃料中加水有利于提高乳化燃料的稳定性。     

On inversive maximal period polynomials over finite fields

Over finite field GF(q) withq a power of an odd primep, we characterize inversive maximal period polynomials in terms of polynomials of orderq + 1, and then we study some properties of polynomials of orderq + 1.This paper was written while the author was visiting the Institute of Information Processing, Austrian Academy of Sciences, AustriaThe author would like to thank the Institute of Information Processing, Austrian Academy of Sciences, Austria, for its hospitality and for using its facilities     

基于部分信息泄露的Hensel提升计算问题

针对传统隐藏数仅局限于模素数或模特定形式合数的问题,利用Hensel提升和格归约技术,提出一种隐藏数问题由模素数向模一般形式合数提升的方法。将隐藏数问题由模素数向模素数方幂提升,运用中国剩余定理得到模一般形式合数下的隐藏数问题。利用该方法证明Hensel提升的离散对数计算,可归约到模素数情况下的隐藏数问题。     

Determining number of clusters and prototype locations via multi-scale clustering

In clustering algorithms, it is usually assumed that the number of clusters is known or given. In the absence of such a priori information, a procedure is needed to find an appropriate number of clusters. This paper presents a clustering algorithm that incorporates a mechanism for finding the appropriate number of clusters as well as the locations of cluster prototypes. This algorithm, called multi-scale clustering, is based on scale-space theory by considering that any prominent data structure ought to survive over many scales. The number of clusters as well as the locations of cluster prototypes are found in an objective manner by defining and using lifetime and drift speed clustering criteria. The outcome of this algorithm does not depend on the initial prototype locations that affect the outcome of many clustering algorithms. As an application of this algorithm, it is used to enhance the Hough transform technique.     

Discrete logarithms inGF(p)

Several related algorithms are presented for computing logarithms in fieldsGF(p),p a prime. Heuristic arguments predict a running time of exp((1+o(1)) ) for the initial precomputation phase that is needed for eachp, and much shorter running times for computing individual logarithms once the precomputation is done. The running time of the precomputation is roughly the same as that of the fastest known algorithms for factoring integers of size aboutp. The algorithms use the well known basic scheme of obtaining linear equations for logarithms of small primes and then solving them to obtain a database to be used for the computation of individual logarithms. The novel ingredients are new ways of obtaining linear equations and new methods of solving these linear equations by adaptations of sparse matrix methods from numerical analysis to the case of finite rings. While some of the new logarithm algorithms are adaptations of known integer factorization algorithms, others are new and can be adapted to yield integer factorization algorithms.