It has been suggested that asteroids between ~100 m and ~100 km in size may be gravitational aggregates of loosely consolidated material. Recently evidence has been mounting to support this idea. Comet breakups, crater chains, doublet craters, giant craters, grooves, asteroid spins, underdense asteroids, asteroid satellites, and unusual asteroid shapes can all be explained to some degree by the...

STATEMENT OF PROBLEM Crowns cemented on short implant abutments may have insufficient retention. PURPOSE The purpose of this study was to evaluate the effect of circumferential grooves on the retention of cemented cast copings on implant abutments. MATERIAL AND METHODS Sixty similarly-shaped implant abutments were divided into 4 groups (n=15): without grooves, with 1 groove, with 2 grooves,...

Analysis of x-ray diagrams of oriented hydrated cytoplasmic microtubules shows that the tubule wall extends from about 70 to 150 A radially. The central region of the wall appears homogeneous, but the outside surface is subdivided by vertical grooves separating the 13 protofilaments and by a steep 10-fold family of grooves. The inside surface is dominated by the 10-start grooves with no clear s...

The amount of scattering of solar radiation by grooves machined into the surfaces of the MMA antenna panels is estimated. Circular cross-section grooves are found to be much more effective than triangular grooves since they scatter over a wider range of angles. The groove pitch should be comparable to or smaller than the wavelength at the highest operating frequency, or about 100300 μm, and ha...

For parallel surfaces, i.e. the oil control ring, micro-geometry completely determines hydrodynamic lubrication (HL). The cross-hatched grooves provide a certain load carrying capacity (LCC) and surface (plateau) roughness can be an additional source. This paper extends earlier work to numerically solve pressure LCC of surfaces with random and/or grooves. influence groove spacing, width depth o...

Phobos’ parallel grooves, which are such a striking feature of its surface, have attracted interest since their discovery on Viking images in 1976 (Veverka and Duxbury, 1977. J. Geophys. Res. 82, 4213–4223.), but their origin is still in dispute today. The great increase in knowledge of Phobos’ surface features effected by images from the High Resolution Stereo Camera (HRSC) onboard the E.S.A. ...

BACKGROUND The resistance form is a key factor for a successful crown fabrication. This in vitro study evaluates the effects of proximal grooves and abutment height on the resistance of single cast crowns in molars with inadequate resistance. METHODS Sixty extracted human molars were prepared to possess 20° of total occlusal convergence for single crown fabrication. All of the prepared teeth ...

OBJECTIVE Polyaxial pedicle screws are a safe, useful adjunct to transpedicular fixation. However, the large screw head size can cause soft tissue irritation, high rod positioning, and facet joint injury. However, the mechanical resistance provided by small and low profile pedicle screws is very limited. We therefore developed a novel, low profile pedicle screw using grooving and blasting treat...