Parasite lineages commonly diverge when host lineages diverge. However, when large clades of hosts and parasites are analyzed, some cases suggest host switching as another major diversification mechanism. The first step in host switching is the appearance of a parasite on an atypical host, or "straggling." We analyze the conditions associated with straggling events. We use five species of colon...

Energy loss straggling of 5.486 MeV alpha particles passing through Melinex, Al, Ni and Cu has been studied as a function of energy loss. The reduction in straggling towards the end of the particle range is predicted by considering the reduction of the stopping power and of the effective charge in the capture and loss of electrons at lower energies. These measurements are compared with theoreti...

background: the advantages of proton beam in radiation therapy- like small lateral scattering as well as absence of exit dose tail in the organs which are after the tumor- make it capable of delivering more treatment doses to the target and much lesser to the critical tissues near it. materials and methods: in this study, the monte carlo mcnpx code has been used to simulate a slab head phantom ...

Background: The advantages of proton beam in radiation therapy- like small lateral scattering as well as absence of exit dose tail in the organs which are after the tumor- make it capable of delivering more treatment doses to the target and much lesser to the critical tissues near it. Materials and Methods: In this study, the Monte Carlo MCNPX code has been used to simulate a slab head phantom ...

The energy-loss straggling of partially ionized heavy ions is determined by the stochastic fluctuations of the energy loss in atomic collisions remaining in a fixed charge state, (collisional straggling) and by the influence of charge-state fluctuations (charge-exchange straggling) [1, 2]. Besides the charge-changing cross sections the charge-exchange straggling depends critically on the differ...

The stopping of Ar beams at energies up to 100 MeV/nucleon in a combination of Al energy degrader and He gas volume was investigated. The range straggling was not largely enhanced by the energy degrader. A Monte Carlo simulation was applied in order to calculate the spatial distribution of stopped ions in the gas.  2002 Elsevier Science B.V. All rights reserved.

Accurate knowledge of ion energy deposition in materials is imperative for a wealth scientific and technological applications. Here, the authors measure energy-loss straggling, i.e., distribution variance transmitted ions, $k\phantom{\rule{0}{0ex}}e\phantom{\rule{0}{0ex}}V$ ions H, He, B, Si membranes. Straggling exhibits significant trajectory dependence all ions. Studying velocity electronic ...

New analytical formulas for the electronic stopping power and the energy loss straggling of low velocity extended charge projectiles in the degenerate electron gas are calculated within the dielectric function method. The stopping and straggling effective charges Zeff of a projectile were analysed. They are found to differ one from the other and to depend on the electron gas density rs, on the ...