R. A. Shelepaev

This article provides the results of reconnaissance surveys carried out in the Alagnur Depression situated in western Mongolia between the Mongolian and Gobi Altai ranges. This area is regarded as a potential corridor for human migrations linking Central Mongolia and Dzungaria during the Pleistocene. Although stratified Middle and Upper Paleolithic sites have been investigated in central Mongolia, possible sublatitudinal routes of dispersal and their connections with coeval complexes in northern China remain poorly understood. Fieldwork in the Alagnur Depression identified two clusters of Paleolithic localities with the surface assemblages exhibiting variable degrees of wind abrasion—Alag-Nur and Ailyn-Tsagaan-1. Characteristics of the lithic industries indicate a dominance of centripetal and orthogonal core reduction methods, with no evidence for blade or Levallois techniques. Despite the conventional nature of distinguishing assemblages based on the degree of aeolian surface alteration of artifacts (corrasion), this method of material differentiation makes it possible to identify a certain find grouping. The comparative analysis of artifacts based on the surface corrosion suggests the presence of distinct chronological groups: the most weathered assemblages likely correspond to the early Middle Paleolithic, whereas less abraded pieces may represent its terminal phases. These findings emphasize the high archaeological potential of the Alagnur Depression as a region preserving traces of early human presence and as a possible transit route between Mongolia and Dzungarian Gobi in China. Among the stratified sites of Mongolia, the Early Middle Paleolithic is known only from the Tsagaan Agui cave in Gobi Altai. However, comparison with the already known exposed complexes of Gobi Altai and Mongolian Altai will make it possible to trace the distribution of typologically similar assemblages.

In this article a computer model of the polariscope is regarded as a 3D scene. In this case, the interference pictures are the result of rendering. The light rays pass through several well-specified polariscope blocks. When developing a suitable renderer, algorithms are selected and estimated for calculating the behavior of the beams based on their physical correctness, speed, etc. A plane parallel plate of an anisotropic crystal is the main block of the scene that affects the resulting image. This article discusses the calculation of the interaction of light with this plate only. Two approaches to calculate orthoscopic interference pictures of optically anisotropic transparent crystals are considered. One is described in many well-known books and bases on definite simplifications. The other is a direct physically based modeling of a light ray path through a plane parallel plate made of a uniaxial crystal taking into account all losses of intensity while passing boundaries between media. The purpose of this paper is to estimate a difference between values obtained via different approaches