Continuum models, based upon both the Volterra and the Peierls descriptions of a screw dislocation ahead of a mode III crack, are used to evaluate the critical loading for dislocation nucleation at the tip of a ® nite pre-blunted crack. Results are presented for various crack tip root radii, for several crack lengths. Moreover, the e€ ect of ledge formation at the crack tip is evaluated. It is ...

Spirocamallanus cricotus sp. n. (= S. pereirai, in part) and S. halitrophus sp. n. are described from marine fishes of the northern Gulf of Mexico. Spirocamallanus cricotus has a ledge anterior to the basal ring in the buccal capsule, similar spicules with a ratio of 1:1.4 to 2.1, 3 pre- and 5 postcloacal papillae, and 8 rectal glands in the female; S. halitrophus lacks the ledge and possesses ...

We study the onset and development of ledge instabilities during growth of vicinal metal surfaces using kinetic Monte Carlo simulations. We observe the formation of periodic patterns at [110] close packed step edges on surfaces vicinal to fcc(001) under realistic molecular beam epitaxy conditions. The corresponding wavelength and its temperature dependence are studied in detail. Simulations sug...

It is necessary to control the size, shape, and uniformity of self-assembled and self-organized nanocrystals in order to use them in real devices. The way to achieve this in epitaxial nanocrystal arrays is by manipulating the bulk stress and/or the surface stress. In this work, an additional and fundamentally different mechanism of CoSi2 nanocrystal size selection is reported, based on a prefer...

INTRODUCTION This study was carried out to evaluate the technical quality of root canal treatment (RCT) performed by undergraduate dental students at the Islamic Azad University in Tehran, Iran. MATERIALS AND METHODS Four-hundred records of patients who had received RCT at faculty of dentistry, between the years 2004-2006 were evaluated. For each treated tooth at least three periapical x-rays...

introduction: this study was carried out to evaluate the technical quality of root canal treatment (rct) performed by undergraduate dental students at the islamic azad university in tehran, iran. materials and methods: four-hundred records of patients who had received rct at faculty of dentistry, between the years 2004-2006 were evaluated. for each treated tooth at least three periapical x-rays...

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We present an analytical, elastic analysis for the energy and relaxation of stepped surfaces. The analysis is based upon the observation that the most prominent feature of the non-reconstructive surface relaxation consists of the atoms at the top of the ledges relaxing inwards toward the bulk. This is modeled by replacing the true atomic structure with a continuum elastic half space subjected t...

The evolution of alternative life-history strategies in fish has largely been overlooked by fisheries managers, although differences in the biology of life-history variants can have important implications for the scale and productivity of fisheries. Cod display strikingly variable colouration in the Gulf of Maine, with redand olive-coloured cod found in close sympatry. Colour types from Cashes ...