Towards an efficient failure detection in MANETs

Mobile ad hoc networks (MANETs) are characterized by a dynamic topology and generally deployed in a hostile environment with limited resources. As a result, the nodes are more vulnerable and are often subject to failures. Therefore, the design of an efficient failure detector in MANETs is a very challenging issue as the detection is proved to be unreliable. Such an achievement amounts to balance between the performances of the accuracy, the completeness and the resource consumption. We present and discuss in this paper a solution for an efficient failure detection in MANETs. This new protocol, called efficient failure detection for MANETs, exploits different mechanisms to improve the completeness and the accuracy of the detection while reducing the traffic overhead. The number of used timers are limited to two for each node thus reducing the complexity of the algorithm. The simulations performed on NS2 platform show the efficiency of efficient failure detection for MANETs comparing with other protocols. Copyright © 2016 John Wiley & Sons, Ltd.     

Microstructured ZnO coatings combined with antireflective layers for light management in photovoltaic devices

We describe microstructured ZnO coatings that improve photovoltaic (PV) device performance through their antireflective properties and their tendency to scatter incoming light at large angles. In many PV devices, reflection from the transparent conductive top contact significantly degrades performance. Traditional quarter‐wave antireflective (AR) coatings reduce surface reflection but perform optimally for only a narrow spectral range and incident illumination angle. Furthermore, in some types of devices, absorption far from the junction increases the rate of recombination, and light management strategies are required to remedy this. The randomly patterned, microstructured ZnO coatings described in this paper, formed via a simple wet etch process, serve as both an AR layer with superior performance to that of a thin film AR coating alone as well as a large angle forward scatterer. We model formation of the coatings and evaluate their AR properties. When combined with a traditional quarter‐wave MgF₂ coating, these microstructured ZnO coatings increase short circuit currents of example Cu(In,Ga)Se₂ (CIGS) devices by over 20% in comparison to those of uncoated devices at normal incidence. A similar improvement is observed for illumination angles of up to 60°. While demonstrated here for CIGS, these structures may prove useful for other PV technologies as well. Published 2016. This article is a U.S. Government work and is in the public domain in the USA. Progress in Photovoltaics: Research and Applications Published by John Wiley & Sons Ltd.     

The times they are a-changin'

Change is the one constant in a constantly changing world, including the world of dietetic practice. Over a 40-year career, I have witnessed and participated in many such changes. Key lessons from my early career with Manitoba Agriculture and Manitoba Health include an understanding of the power of teamwork, of the importance of communication skills, of the need for shared knowledge and expertise, and of ways to connect nutrition messages with food and eating. Later, my work as director of education in a family medicine residency program taught me the value of building a portfolio of knowledge and skills and of working with families. Similarly, my work with the Organization for Cooperation in Overseas Development led me to appreciate the need for cultural sensitivity in our work. Opportunities with Dietitians of Canada have shown me that future directions must include continued interdisciplinary development of policy and position papers. Other important challenges include determining issues relevant to various areas of dietetic practice, working to achieve Vision 2020 goals, and inspiring and nurturing new leadership among younger Dietitians of Canada members.     

Concentrations and fluxes of salmon-derived polychlorinated biphenyls (PCBs) in lake sediments

Fourteen sediment cores were collected from 10 lakes spanning a large gradient of sockeye salmon returns (0-40 000 spawners km(-2)) in Alaska and British Columbia in 1995-98 and 2002/03. The cores were analyzed for 210Pb to determine sedimentation rates and focusing factors. Polychlorinated biphenyl (PCBs) concentrations in the surface sediments (0-2 cm) were highly correlated with the number of sockeye salmon returns to each nursery lake. For 2002/03, the correlation between PCB concentration and number of salmon spawners was best with no correction factors applied, but decreased considerably when corrected for sedimentation rates, and was improved again by correcting for sediment focusing. Although sigmaPCB concentrations were similar in 1995-98 and 2002/03, the congener patterns varied. Because salmon are the dominant source of PCBs for most of these lakes, variation in sediment congener pattern likely derives from variation in congener patterns carried by the salmon. Overall, total PCB input by salmon has remained relatively constant since 1995. Unlike temperate Great Lakes contaminant studies, the North American west-coast lakes dominated by salmon bio-transport showed no sign of recent decrease in PCBs.     

The Limits to Authority: Developer Interventions and Neighbour Problems on a Master Planned Estate

Master planned estates are large suburban developments built by a private sector developer. As part of its pursuit of building ready-made communities, the Developer becomes active in the management of the estate for years after its completion, subsequently finding itself in the difficult position of running, rather than simply building, new communities. In this paper, this challenge facing the Developer is explored with reference to Foucault’s writing on the problematics of governing under liberalism and the question of what is within the competence of the state and what is not. This paper shows how corporate property developers pose themselves similar questions and face the effects of demarcating certain spheres of residential life as not within their domain. The example addressed here is the issue of managing problems between neighbours and the tensions arising from residents’ expectations that this is indeed a matter of development control.     

Implacing Architecture into the Practice of Placemaking

To place architecture beyond expert culture into the practice of placemaking is an attempt to make the profession and discipline a more relevant, responsible, complex, and contradictory practice. The proposed relocation moves the practice of architecture into the borders between modern and postmodern theories of knowledge and social/cultural practices that require, but do not privilege expert knowledges. One aspect of this relocation is the requirement of more open and collaborative processes that can create profound opportunities for democratic action and the celebration of everyday life.     

Survival of Campylobacter jejuni on beef and pork under vacuum packaged and retail storage conditions: examination of the role of natural meat microflora on C. jejuni survival

The ability of Campylobacter jejuni ATCC 11168 to survive on beef and pork stored under chilled, vacuum packaged and retail display conditions were examined. In addition, the effect of natural microflora on commercial beef and pork on the survival of C. jejuni under these storage conditions was examined. When sterile cores of beef and pork were inoculated with ∼10⁵ to 10⁶ cfu cm⁻²C. jejuni, and were stored under aerobic or vacuum packaged conditions at −1.5 or 4 °C, its numbers dropped significantly and C. jejuni could not be enumerated by direct plating after 21 d of the 6 wks study. In contrast, survival of C. jejuni on commercial vacuum packaged beef and pork was significantly enhanced, resulting in only 1 log cfu cm⁻² reduction at the end of 6 wks. During 7 d of display in a retail case, numbers of C. jejuni dropped quickly, but could be enumerated by direct plating even after the 7 d. The presence of high numbers of inoculated C. jejuni on beef and pork had no significant effect on the natural microflora numbers compared to uninoculated controls when the meat was stored either in vacuum or in a retail display case. These results show that natural microflora on vacuum packaged meat afford enhanced survival of C. jejuni present on the surfaces of both beef and pork when stored at refrigeration temperatures. Hence, strict hygienic practices or the implementation of decontamination technologies are recommended to ensure safety of meat with respect to this pathogen.     

Assessment of taxonomic encoding categories in different populations.

Assessed the degree of taxonomic category encoding in 160 low-socioeconomic status (SES) Black and middle SES White children. D. D Wickens's (see record 1970-04540-001) release from proactive interference task was used to index categorical encoding of animal and clothing items. Build-up and release from proactive interference was observed for each population at 2 different grade levels (2nd and 4th). The degree of proactive interference build-up and release was not affected by either population membership or grade level. These results provide conclusive evidence of the availability of taxonomic encoding categories in the groups sampled. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

An anion exchange resin from soybean hulls

Agricultural by‐products are generally poor adsorbents of anions in solution. Therefore, modification of the by‐product could enhance its anion exchange capabilities. The objective of this study was to increase the anion exchange properties of the agricultural by‐product, soybean hulls, by chemical modification. Soybean hulls were quaternized with the quaternizing agent, N‐(3‐chloro‐2‐hydroxypropyl) trimethylammonium chloride, in the presence of a strongly alkaline environment. This modification increased the amount of positive charge on the hulls as evidenced by increased nitrogen content and increased uptake of anions compared with the unmodified hulls. A method to optimize the anion exchange properties of the hulls was developed. Ion exchange properties of the hulls toward anions of environmental significance, namely arsenate (As), chromate (Cr), dichromate (Cr₂), phosphate (P) and selenate (Se) were determined. The modified hulls were also compared with commercial cellulose‐based and synthetic anion exchange resins in their ability to remove these anions from solution. The experimental and commercial resins were also compared for their ability to remove a mixture of arsenate, chromate, dichromate and selenate from laboratory prepared solutions to levels below the maximum contaminant levels for these anions in drinking water as specified by the US Environmental Protection Agency (US EPA). Our results demonstrate that the soy hull resin is more efficient in anion removal than the commercial cellulose‐based resin but not as effective as the commercial synthetic resin. Published in 2003 for SCI by John Wiley & Sons, Ltd.