News Update on Squirrel : April 21

[1] Squirrel: a decentralized peer-to-peer web cache

This paper presents a decentralized, peer-to-peer web cache called Squirrel. The key idea is to enable web browsers on desktop machines to share their local caches, to form an efficient and scalable web cache, without the need for dedicated hardware and the associated administrative cost. We propose and evaluate decentralized web caching algorithms for Squirrel, and discover that it exhibits performance comparable to a centralized web cache in terms of hit ratio, bandwidth usage and latency. It also achieves the benefits of decentralization, such as being scalable, self-organizing and resilient to node failures, while imposing low overhead on the participating nodes.

[2] On the spatial spread of the grey squirrel in Britain

We present a diffusion–competition model to describe the interaction between the externally introduced grey squirrel and the indigenous red squirrel in Britain. We estimate the model parameters from field data. Solution of the model predicts waves of grey squirrel invasion with speed of invasion typical of that observed in the field. Numerical solution of the model on a two-dimensional domain gives population distributions qualitatively similar to those observed. We suggest that competition alone could account for the observed displacement of the red squirrel by the grey in large regions of Britain. The solutions are qualitatively similar to those for a single species spreading in the absence of competition. The quantitative difference is because competition slows down the speed of advance of the invading species.

[3] Multiple paternity in Belding’s ground squirrel litters

Sexually receptive female Spermophilus beldingi (Rodentia: Sciuridae) usually mate with several different males. The paternity of 27 litters born in 1977 and 1978 was ascertained by combining field observations of mating with laboratory paternity exclusion analyses. Most of the litters (78 percent) were multiply sired, usually by two or three males. This may be the highest frequency of multiple paternity ever directly demonstrated in a natural population.

[4] Oesophageal and Gastric Morphology of the African Rope Squirrel Funisciurus anerythrus (Thomas, 1890)

Aim: The aim of this study is to evaluate the gross, histological and histochemical features of the oesophagus and stomach of the African rope squirrel (Funisciurus anerythrus) were studied.

Study Design: Experimental morphological study was carried out.

Methodology: Gross dissection, routine histological technique and histochemistry using PAS and AB stains were conducted.

Results: Grossly the oesophagus was a simple musculo-membranous short tube weighing 0.17±0.02 g and measured 8.5±0.1 cm in length and the stomach was visibly uncompartmentalized, it weighed 4.98±0.05 g and measured 4.32±0.3 cm in length. Histologically, the oesophagus showed a non-keratinized stratified squamous epithelium with longitudinal folds in the cervical part. The laminae muscularis mucosa was prominent with a thick smooth muscle layer in the thoracic part. Submucosal glands were absent. The muscularis externa were typical consisting of inner circular and outer longitudinal smooth muscle layers as in many rodents. The internal lining mucous cells were PAS- positive and AB- negative. The gastric mucosa exhibited typical gastric pits, throughout the three regions of the stomach (cardia, fundus, and pylorus) which lead to gastric glands. Well developed gastric glands were more abundant in the fundic part than in other regions and these glands showed mucoid cells lining the upper neck regions and distinct chief and parietal cells. The surface mucosal lining was PAS-positive and weakly AB –positive. The pyloric glands were weakly PAS-positive and strongly AB-negative.

Conclusions: These findings indicated similarities to most omnivorous rodent species.


[5] Approximate Solutions for a Couple of Reaction-diffusion Equations with Self-diffusion


In this paper, a competition model of a reaction diffusion system with self-diffusion has been studied using homotopy perturbation method, variational iteration method and Finite element method FEM (COMSOL package). The traveling wave solutions for this system are found and compared numerically.It was shown that the competition will lead at the end of the winning of one species. The effect of self diffusion is shown in the dispersing of traveling wave solution. Also, it was shown that the solution of finite element method and homotopy perturbation method are convergent to each other compared to the variation iteration method.

 


Reference

[1] Iyer, S., Rowstron, A. and Druschel, P., 2002, July. Squirrel: A decentralized peer-to-peer web cache. In Proceedings of the twenty-first annual symposium on Principles of distributed computing (pp. 213-222).

[2] Okubo, A., Maini, P.K., Williamson, M.H. and Murray, J.D., 1989. On the spatial spread of the grey squirrel in Britain. Proceedings of the Royal Society of London. B. Biological Sciences238(1291), pp.113-125.

[3] Hanken, J. and Sherman, P.W., 1981. Multiple paternity in Belding’s ground squirrel litters. Science212(4492), pp.351-353.

[4] Igbokwe, C.O. and Obinna, S.J., 2016. Oesophageal and gastric morphology of the African Rope Squirrel Funisciurus anerythrus (Thomas, 1890). Journal of Applied Life Sciences International, pp.1-9.

[5] Rasheed, S.M., Yousif, M.A. and Mahmood, B.A., 2015. Approximate Solutions for a Couple of Reaction-diffusion Equations with Self-diffusion. Journal of Advances in Mathematics and Computer Science, pp.1-11.

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