In pursuit for impeccable veracity

I study the institution of avoiding to hire one’s school own PhD graduates for assistant professorships. I argue that this institution is necessary to create better incentives for researchers to incorporate new information in studies, facilitating the convergence to asymptotic learning of the studied fundamentals.academic inbreeding; moral hazard; knowledge; information dissemination

Copper-Catalyzed Arylation of 1\u3cem\u3eH\u3c/em\u3e-Perfluoroalkanes

A general method has been developed for arylation of readily available 1H-perfluoroalkanes. The method employs aryl iodide and 1H-perfluoroalkane reagents, DMPU solvent, TMP2Zn base, and a copper chloride/phenanthroline catalyst. Preliminary mechanistic studies are reported

Parametric study of the conditions of supershear crack propagation in brittle materials

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in AIP Conference Proceedings 1683, 020209 (2015) and may be found at https://doi.org/10.1063/1.4932899.The paper is devoted to the numerical analysis of the conditions of acceleration of dynamically propagating longitudinal shear cracks from sub-Rayleigh to intersonic/supershear velocities. We showed that an ability of the initial crack to propagate in supershear regime can be predicted with use of the empirically derived dependence of the geometrical criterion of sub-Raleigh-to-intersonic transition on material and crack parameters

Unidirectional Amplification and Shaping of Optical Pulses by Three-Wave Mixing with Negative Phonons

A possibility to greatly enhance frequency-conversion efficiency of stimulated Raman scattering is shown by making use of extraordinary properties of three-wave mixing of ordinary and backward waves. Such processes are commonly attributed to negative-index plasmonic metamaterials. This work demonstrates the possibility to replace such metamaterials that are very challenging to engineer by readily available crystals which support elastic waves with contra-directed phase and group velocities. The main goal of this work is to investigate specific properties of indicated nonlinear optical process in short pulse regime and to show that it enables elimination of fundamental detrimental effect of fast damping of optical phonons on the process concerned. Among the applications is the possibility of creation of a family of unique photonic devices such as unidirectional Raman amplifiers and femtosecond pulse shapers with greatly improved operational properties.Comment: 6 pages, 4 figures. arXiv admin note: text overlap with arXiv:1304.681

Key role of elastic vortices in the initiation of intersonic shear cracks

Using the particle-based method of movable cellular automata, we analyze the initiation and propagation of intersonic mode II cracks along a weak interface. We show that the stress concentration in front of the crack tip, which is believed to be the mechanism of acceleration of the crack beyond the speed of shear waves, is due to the formation of an elastic vortex. The vortex develops in front of the crack during the short initial period of crack propagation. It expands and moves away from the crack tip and finally detaches from it. Maximum stress concentration in the vortex is achieved at the moment of detachment of the vortex. The crack can accelerate towards the longitudinal wave speed if the magnitude of shear stresses in the elastic vortex reaches the material shear strength before vortex detachment. We have found that for given material parameters, the condition for the unstable accelerated crack propagation depends only on the ratio of the initial crack length to its width (e.g., due to surface roughness)

On the role of scales in contact mechanics and friction between elastomers and randomly rough self-affine surfaces

The paper is devoted to a qualitative analysis of friction of elastomers from the point of view of scales contributing to the force of friction. We argue that – contrary to widespread opinion – friction between a randomly rough self-affine fractal surface and an elastomer is not a multiscale phenomenon, but is governed mostly by the interplay of only two scales – as a rule the largest and the smallest scales of roughness of the contacting bodies. The hypothesis of two-scale character of elastomer friction is illustrated by computer simulations in the framework of the paradigm of Greenwood, Tabor and Grosch using a simplified one-dimensional model

Recent Russian remote sensing investigations in Antarctica within the framework of scientific traverses

This paper includes a short historical review of Russian and Soviet scientific traverses to study the Antarctic inland. The first traverse left on April 2, 1956. It resulted in the opening of the first Russian inland research station named Pionerskaya and provided the first geophysical and glaciological data on regions inland of the Antarctic coast. By 1965, a number of regional inland scientific traverses had been completed and the first Atlas of Antarctica was published in 1966. The atlas presented the main achievements of that time. After the discovery of Lake Vostok, Russian scientists commenced remote sensing investigations to study this unique natural phenomenon. The propagation of acoustic and electromagnetic waves in the glacier near Vostok Station were measured to provide important geophysical data. Radio-echo sounding data showed that Lake Vostok is isolated and separated from the rest of the Antarctic subglacial hydrosphere. The total area of the lake is 15 790 km2, excluding 365 km2 occupied by 11 islands. Reflection seismic soundings of Lake Vostok estimated a total volume of about 6 100 km3, an average depth of about 400 m, and a maximum depth of 1 200 m. Since 2008, there have been a number of scientific traverses between Mirny and Vostok stations and between Progress and Vostok stations. The data collected during the traverses have provided new insights into sub-ice topography and ice sheet structure, and have led to the discovery of subglacial lakes near Komsomolskaya Station and under Pionerskaya Station