RNAs that localize to the vegetal cortex during Xenopus laevis oogenesis have been reported to function in germ layer patterning, axis determination, and development of the primordial germ cells. Here we report on the genome-wide, comparative analysis of differentially localizing RNAs in Xenopus laevis and Xenopus tropicalis oocytes, revealing a surprisingly weak degree of conservation in respe...

High rates of erosion (1-15 mm/yr) of fluvial strata have persisted over intervals of 0.2-1.5 m.y. and across areas of 60-2000 km 2 in the Cenozoic foreland basin of northern Pakistan. These rates occur in areas associated with thrust shortening, and they indicate that erosion nearly kept pace with the rates of latest Miocene to Pleistocene uplift. Such high rates of erosion are predicted to pr...

The Saint Petersburg Society of Naturalists has reinstated the Alexander O. Kowalevsky Medal. This article announces the winners of the first medals and briefly reviews the achievements of A.O. Kowalevsky, the Russian comparative embryologist whose studies on amphioxus, tunicates and germ layer homologies pioneered evolutionary embryology and confirmed the evolutionary continuity between invert...

The objective of this paper is to provide a robust representation of moving images based on layers. To that goal, we have designed e cient motion estimation and segmentation techniques by a ne model tting suitable for the construction of layers. Layered representations, originally introduced in [4] are important in several applications. In particular, they are very appropriate for object tracki...

We study the Tukey layers and convex of a planar point set, which consists n points independently uniformly sampled from polygon with k vertices. show that expected number vertices on first t is O ( log ⁡ / ) 3 2 . also lower bound Ω for both quantities in special cases where = , 4 The implications those results average-case analysis two computational geometry algorithms are then discussed.