Bond-slip analysis via a cohesive-zone model simulating damage, friction and interlocking

A recently proposed cohesive-zone model which effectively combines damage, friction and mechanical interlocking has been revisited and further validated by numerically simulating the pull-out test, from a concrete block, of a ribbed steel bar in the post-yield deformation range. The simulated response is in good agreement with experimental measurements of the bond slip characteristics in the post-yield range of deformed bars reported in the literature. This study highlights the main features of the model: with physically justified and relatively simple arguments, and within the sound framework of thermodynamics with internal variables, the model effectively separates the three main sources of energy dissipation, i.e. loss of adhesion, friction along flat interfaces and mechanical interlocking. This study provides further evidence that the proposed approach allows easier and physically clearer procedures for the determination of the model parameters of such three elementary mechanical behaviours, and makes possible their interpretation and measurement as separate material property, as a viable alternative to lumping these parameters into single values of the fracture energy. In particular, the proposed approach allows to consider a single value of the adhesion energy for modes I and II

On the implementation of sustainability: The role of the economic development officer

Agencies involved in economic development recognize the need to take a more sustainable approach in their work. Economic Development Officers (EDOs) can play a significant role in ensuring there are processes in place within their organization to promote sustainable development. This paper provides a brief background on this subject and highlights local and regional policies to assist the EDO in developing programs designed to foster sustainable development at the local and regional levels. The author argues that EDOs with an inherent understanding of the principles of quality of life; fairness and equity; participation and partnership; care for the natural environment; and thought for the future are best positioned to effect change. However, the degree of change will largely depend on the commitment and support of the community or the region.Keywords: sustainable development, Economic Development Officer (EDO), polic

Fatty acid composition of Mediterranean buffalo milk fat

The purpose of this research was to investigate the variation in fatty acid composition of milk fat from four buffalo (Bubalus bubalis) herds under different feeding management and ration composition. Changes in milk fatty acid composition were monitored on a weekly basis. Saturated fatty acids (65.5%) predominated in buffalo milk fat; monounsaturated and polyunsaturated fatty acids were 27.0% and 4.5%, respectively. Of saturated fatty acids, the content of palmitic acid was the highest (30.6%) followed by stearic acid (12.0%) and myristic acid (10.7%). Of the unsaturated fatty acids the content of oleic acid was the highest (26.6%). The average content of conjugated linoleic acid (0.76±0.33) was higher than the maximal values generally reported for dairy cow

Effect of Enterococcus faecium SF68 on growth performance and in vivo digestibility in buffalo calves

The effect of dietary supplementation with Enterococcus faecium strain SF68 on growth performance, faecal consistency and in vivo digestibility in buffalo (Bubalus bubalis) calves was evaluated. Forty calves were randomly assigned at 10 d of age to one of four treatments: (A) milk replacer with no additive, (B) milk replacer supplemented with 0.17 g/l of viable (2 x l09 cfu/g) E. faecium bacteria daily for 3 days with an interval of 7 days throughout 11 weeks, (C) milk replacer supplemented with E. faecium daily for 4 weeks, (D) milk replacer supplemented with E. faecium daily for 11 weeks. A total mixed ration was offered ad libitum from 5th week of the experimental period. Faecal score was significantly better in E. faecium-treated calves than control ones. The use of E. faecium had no effect on average daily gain at any stage, total body weight (BW) gain, dry matter intake or total tract digestibility. Therefore, E. faecium supplementation may be able to act favourably on the health of the gastro-intestinal trac

Well quasi-orders and context-free grammars

Let G be a context-free grammar and let L be the language of all the words derived from any variable of G. We prove the following generalization of Higman's theorem: any division order on L is a well quasi-order on L. We also give applications of this result to some quasi-orders associated with unitary grammars. (C) 2004 Elsevier B.V. All rights reserved

Latency-bounded target set selection in signed networks

It is well-documented that social networks play a considerable role in information spreading. The dynamic processes governing the diffusion of information have been studied in many fields, including epidemiology, sociology, economics, and computer science. A widely studied problem in the area of viral marketing is the target set selection: in order to market a new product, hoping it will be adopted by a large fraction of individuals in the network, which set of individuals should we “target” (for instance, by offering them free samples of the product)? In this paper, we introduce a diffusion model in which some of the neighbors of a node have a negative influence on that node, namely, they induce the node to reject the feature that is supposed to be spread. We study the target set selection problem within this model, first proving a strong inapproximability result holding also when the diffusion process is required to reach all the nodes in a couple of rounds. Then, we consider a set of restrictions under which the problem is approximable to some extent

Digestive Enzymes in the Crayfish Cherax albidus: Polymorphism and Partial Characterization

We will deal with the partial characterization and the activity of the following digestive enzymes: amylase, pectinase, alginase, lipase, and protease present in the digestive tract of juvenile freshwater crayfishCherax albidus. Gastric juices, the hepatopancreas, and the intestine were sampled for enzyme analysis. Among carbohydratases, amylase activity was the highest. It was significantly higher in the intestine than in the gastric juice and hepatopancreas. Lipase activity was significantly higher in the hepatopancreas and the intestine compared to the gastric juice. Both alkaline and acid proteases were found. Alkaline proteases were characterized by employing specific protease inhibitors. Both trypsin and chymotrypsin activity was detected. The majority of alkaline protease activity was ascribable to trypsin. Several isoforms of digestive enzymes were identified by gel electrophoresis. This work provides basic information to study the digestive abilities of crayfish