Absolute Configuration of 4-Methyl-3-Heptanone and 4-Methyl-3-Heptanol from Mandibular Glands of Virgin Males and Females ofAtta sexdens rubropilosa

(S)-;(+)-4-Methyl-3-heptanone is the principal component in the secretion from the mandibular glands of unmated and mated males and females ofAtta sexdens rubropilosa. In mated and unmated females, it is essentially the only component in the glandular secretion. In unmated males up to 50% of the secretion is a mixture of (3S, 4S)- and (3R, 4S)-4-methyl-3-heptanol. After mating, the amount of alcohol in the males decreases markedly.     

Characterization of polymer‐layered silicate (clay) nanocomposites by transmission electron microscopy and X‐ray diffraction: A comparative study

Several polymer‐layered silicate (clay) nanocomposites (PLSNs) were analyzed by transmission electron microscopy (TEM) and wide‐angle X‐ray diffraction (XRD) in an effort to characterize the nanoscale dispersion of the layered silicate. The PLSNs investigated included thermoset (cyanate esters) and thermoplastic polymers (polystyrene, nylon 6, and polypropylene‐g‐maleic anhydride). The results of this study reveal that the overall nanoscale dispersion of the clay in the polymer is best described by TEM, especially when mixed morphologies are present. XRD is useful for the measurement of d‐spacings in intercalated systems but cannot always observe low clay loadings (<5%) or be used as a method to identify an exfoliated nanocomposite where no XRD peaks are present (constituting a negative result). Most importantly, the study showed that XRD is not a stand‐alone technique, and it should be used in conjunction with TEM. Our studies suggest that new definitions, or a clarification of existing definitions, are needed to properly describe the diversity of PLSN nanostructures seen in various materials. Published 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1329–1338, 2003     

深刻的对比：蒙特利尔的新学院大楼

很多大学都坐落在蒙特利尔，如康考迪亚大学、魁北克大学蒙特利尔分校（UQAM）以及蒙特利尔大学（UdeM）。自从这些大学建校以来，其校园就是一直是主要建筑作品的栖息地。本文将围绕着康考迪亚大学的工程学、计算机科学和视觉艺术这几个学科的综合大楼（EV-Complex）、UQAM市区校园的扩建建筑以及作为UdeM的扩建项目——高等综合理工学院一部分的Claudette MacKay Lessonde和Pierre Lassonde馆展开论述。虽然这些工程都拥有相似的建筑感，但它们也展示了极为不同的设计技巧。     

Clearing the Air on EPA's New Chief

On November 8, 2016, the citizens of the United States elected not just a new government, but a very different government. With the election of Donald Trump as the 45th president of the United States and the results in the many contested congressional races, the pendulum of politics swung, perhaps harder than it has swung in at least several decades.     

A stochastic performance model for pipelined Krylov methods

Pipelined Krylov methods seek to ameliorate the latency due to inner products necessary for projection by overlapping it with the computation associated with sparse matrix‐vector multiplication. We clarify a folk theorem that this can only result in a speedup of 2× over the naive implementation. Examining many repeated runs, we show that stochastic noise also contributes to the latency, and we model this using an analytical probability distribution. Our analysis shows that speedups greater than 2× are possible with these algorithms. Copyright © 2016 John Wiley & Sons, Ltd.     

Cracking processes in Barre granite: fracture process zones and crack coalescence

This paper presents a comprehensive study of the cracking and coalescence behavior of granite specimens with pre-existing flaw pairs. Uniaxial compressions tests were conducted on Barre granite with pre-existing flaw pairs of varying inclination angles $(\upbeta )$ , bridging angles $(\alpha )$ and ligament lengths (L). The cracking processes were recorded using a high speed camera to capture crack initiation and determine the mode (tensile or shear) of cracking. Visible fracture process zones of grain lightening, referred to as “white patching”, were also observed. White patching corresponded to fracture process zones that developed before visible cracks appeared. Cracks were typically preceded by a corresponding linear white patching. Diffusive area white patching was also observed near locations where surface spalling eventually occurred. Shear cracks occurred less often when compared to other brittle materials such as gypsum and marble and tensile cracks were typically much more jagged in shape (saw-toothed) due to the larger size and higher strength mineral grains of granite. Crack coalescence behavior trended from indirect to direct shear and combined shear-tensile to direct tensile coalescence as the flaw pair bridging angle $(\alpha )$ or flaw angle $(\upbeta )$ increased. As the ligament length (L) between flaws increased, more indirect coalescence was observed. As expected, due to the increased occurrence of tensile cracking in granite, more indirect tensile coalescence was observed in granite compared to other materials previously studied.     

Reduced order mesh optimisation using proper orthogonal decomposition and a modified cuckoo search

A new mesh optimisation scheme, reduced order mesh optimisation, is introduced. The technique uses proper orthogonal decomposition to reduce the number of dimensions in a mesh optimisation problem. This reduction in dimensionality allows the expression of the optimisation problem globally rather than the more traditional local mesh optimisation or smoothing algorithms. To perform the optimisation, the recently developed gradient‐free technique modified cuckoo search is applied. The effectiveness of the algorithm is shown by considering the problem of optimising meshes for use in co‐volume techniques. Co‐volume techniques require the existence of two mutually orthogonal meshes; this is achieved by utilising the Delaunay–Voronoi dual. A combination of considering the problem globally and the use of a gradient‐free technique results in a scheme that significantly outperforms previous methods in solving this particular problem. Although the examples presented in this paper are specific to optimising dual meshes, the technique is general and can be simply modified to any mesh optimisation problem. Copyright © 2012 John Wiley & Sons, Ltd.     

An analysis of driving and working hour on commercial motor vehicle driver safety using naturalistic data collection

Current hours-of-service (HOS) regulations prescribe limits to commercial motor vehicle (CMV) drivers’ operating hours. By using naturalistic-data-collection, researchers were able to assess activities performed in the 14-h workday and the relationship between safety-critical events (SCEs) and driving hours, work hours, and breaks. The data used in the analyses were collected in the Naturalistic Truck Driving Study and included 97 drivers and about 735,000 miles of continuous driving data. An assessment of the drivers’ workday determined that, on average, drivers spent 66% of their shift driving, 23% in non-driving work, and 11% resting. Analyses evaluating the relationship between driving hours (i.e., driving only) and SCE risk found a time-on-task effect across hours, with no significant difference in safety outcomes between 11th driving hour and driving hours 8, 9 or 10. Analyses on work hours (i.e., driving in addition to non-driving work) found that risk of being involved in an SCE generally increased as work hours increased. This suggests that time-on-task effects may not be related to driving hours alone, but implies an interaction between driving hours and work hours: if a driver begins the day with several hours of non-driving work, followed by driving that goes deep into the 14-h workday, SCE risk was found to increase. Breaks from driving were found to be beneficial in reducing SCEs (during 1-h window after a break) and were effective in counteracting the negative effects of time-on-task.     

Intraspecies diversity of Lactobacillus sakei response to oxidative stress and variability of strain performance in mixed strains challenges

Lactobacillus sakei is a meat-borne lactic acid bacterium species exhibiting a wide genomic diversity. We have investigated the diversity of response to various oxidative compounds, between L. sakei strains, among a collection representing the genomic diversity. We observed various responses to the different compounds as well as a diversity of response depending on the aeration conditions used for cell growth. A principal component analysis revealed two main phenotypic groups, partially correlating with previously described genomic clusters. We designed strains mixes composed of three different strains, in order to examine the behavior of each strain, when cultured alone or in the presence of other strains. The strains composing the mixtures were chosen as diverse as possible, i.e. exhibiting diverse responses to oxidative stress and belonging to different genomic clusters. Growth and survival rates of each strain were monitored under various aeration conditions, with or without heme supplementation. The results obtained suggest that some strains may act as “helper” or “burden” strains depending on the oxidative conditions encountered during incubation. This study confirms that resistance to oxidative stress is extremely variable within the L. sakei species and that this property should be considered when investigating starter performance in the complex meat bacterial ecosystems.