Let $p:Xlo B$ be a locally trivial principal G-bundle and $wt{p}:wt{X}lo B$ be a locally trivial principal $wt{G}$-bundle. In this paper, by using the structure of principal bundles according to transition functions, we show that $wt{G}$ is a covering group of $G$ if and only if $wt{X}$ is a covering space of $X$. Then we conclude that a topological space $X$ with non-simply connected universal...

There is controversy in the literature regarding a number of topics related to anterior cruciate ligament (ACL)reconstruction. The purpose of this article is to answer the following questions: 1) Bone patellar tendon bone (BPTB) reconstruction or hamstring reconstruction (HR); 2) Double bundle or single bundle; 3) Allograft or authograft; 4) Early or late reconstruction; 5) Rate of return to sp...

the main purpose of this study is to perform numerical simulation of nanofluids as the coolant in vver-440 fuel rod bundle. the fuel rod bundle contains 60 fuel rods with length of 960 mm and 4 spacer grids. in vver-440 fuel rod bundle the coolant fluid (water) is in high pressure and temperature condition. in the present thermo-hydraulic simulation, water-al2o3 nanofluids containing various vo...

catheter ablation is an accepted, highly effective modality of treatment for cardiac arrhythmias in children. the success rate depends on the operator’s experience, especially in cases involving complex anatomies. we hereby report our recent experience of successful ablation of accessory pathways in three children with complex congenital heart diseases. the first case was a 7-year-old girl with...

The potential distribution within the internodal axon of mammalian nerve fibers is derived by applying known node potential waveforms to the ends of an equivalent circuit model of the internode. The complete spatial/temporal profile of action potentials synthesized from the internodal profiles is used to compute the node current waveforn, and the extracellular action potential around fibers cap...

Given a real-analytic Riemannian manifold M there exists a canonical complex structure on part of its tangent bundle which turns leaves of the Riemannian foliation on TM into holomorphic curves. A Grauert tube over M of radius r, denoted as T rM , is the collection of tangent vectors of M of length less than r equipped with this canonical complex structure. We say the Grauert tube T rM is rigid...

Amongst the wide range of metal foam applications, the heat exchange industry is the most notable. Heat exchangers are devices that transfer heat from one medium to another that in most cases the two media are air and water. Specifically, aircooled heat exchangers consist of a number of water tubes to transfer the heat between the pumped air and the flowing water through the tubes. Covering the...

A liquid falling between horizontal tubes can take the form of droplets, jets, or a continuous sheet mode, depending on the flow rate. The so-called falling-film flow regime is important to heat and mass transfer, and to maintaining wetted-surface conditions in a falling-film tube bundle, and the performance of such tube bundles is important in many air-conditioning systems. In this paper, we r...

In the last decades, one of main objectives pursued in field computational fluid dynamics has been development turbulent flow models and simulations techniques capable generating predictions patterns accurate enough to many industrial applications a reasonable wall-clock time at an acceptable cost. Very often, trade-off be sought between engineer’s expectations regarding accuracy model limited ...