The variability associated with Sibudu's Howiesons Poort Industry highlights the unpredictable trajectory of technology in the Middle Stone Age. We reach this conclusion through a study of the technology on quartz from one of the Howiesons Poort layers (Grey Sand) from Sibudu rock shelter. Quartz bifacial technology has previously been described at the site, but this new in-depth study of the q...

A b s t r a c t A n X-ray diffraction method for determining quartz in sediments is described which is both rapid and precise, with a coefficient of variation of 1.9 per cent. Samples are ignited at 950~ prior to X-ray analysis. This removes the interference of clay peaks, increases the relative intensity of the quartz peaks and reduces the initial matrix variation of samples. The peak area rat...

OpenGL is getting used more in window system as a way of improving performance and enabling new functionality. Examples of two systems using different approaches of how OpenGL is being used are Quartz Extreme and Fresco. Quartz Extreme uses window composition which assures fast redisplay and Fresco on the other hand uses a structured graphics approach which utilises OpenGL on a much lower level...

The available shock-wave data for solid .a quartz in the stishovite pressure regime are reduced to a 25øC isotherm and an adiabat, centered at standard conditions, using recent standard density, enthalpy, and coefficient of thermal expansion data. The calculated isothermal bulk modulus, 3 Mb, as determined from the Bireh-Murnaghan equation, depends critically on the value of (dK/dP)•, at zero p...

Two biodegradable quaternary ammonium salts were synthesized and used as cationic collectors in processing iron ores by froth flotation. The flotation behaviors of iron minerals with the new biodegradable quaternary ammonium collectors were investigated by micro-flotation tests of quartz (SiO2) and magnetite (Fe3O4). It was observed that the new biodegradable collectors were effective in separa...

In the preceding paper of this series (1) it was shown that carbon particles are ingested by rat leucocytes three or four times as readily as quartz particles of approximately the same size. Variations were found, however, in this ratio between the rates of ingestion of carbon and quartz during the course of a single experiment which suggested that significant variations might be produced by va...

The signature scheme Quartz is based on a trapdoor function G belonging to a family called HFEv-. It has two independent security parameters, and we claim that if d is big enough, no better method to compute an inverse of G than the exhaustive search is known. Such a (quite strong) assumption, allows to view Quartz as a general construction, that transforms a trapdoor function into a short sign...

Preferred orientation in granitic mylonites from the Santa Rosa mylonite zone in Southern California is investigated with time-of-flight neutron diffraction. Quartz and biotite display strong preferred orientation, whereas, feldspar alignment is weak. For quartz, a c-axis maximum in the intermediate fabric direction is consistent with dynamic recrystallization. Pole figures for positive and neg...