Estimating change-points in biological sequences via the cross-entropy method

The genomes of complex organisms, including the human genome, are known to vary in GC content along their length. That is, they vary in the local proportion of the nucleotides G and C, as opposed to the nucleotides A and T. Changes in GC content are often abrupt, producing well-defined regions.     

Manifestation of the superconducting pairing of repulsive particles with a large total momentum in Andreev reflection

Features of Andreev reflection at the normal metal-superconductor interface in the presence of repulsive-interaction-induced pairing with a large total momentum K have been analyzed. When the direction of the motion of a hole arising upon the formation of a pair with K ≠ 0 by an incident electron corresponds to transmission, the intensity of Andreev reflection decreases compared to the case K = 0. Another cause of the decrease in the intensity is that, owing to the repulsive interaction, the superconducting order parameter has a zero line, and the quasiparticle energy minimum, which determines the turning point, does not coincide with the Fermi contour on which the quasiparticle charge changes its sign (charge asymmetry).     

Emission of terahertz radiation from GaAsN/GaAs heterostructures in an electric field

Emission of terahertz radiation from strained Be-doped GaAsN layers has been revealed at 4.2 K in postbreakdown electric fields. Heavy and light hole subbands are split in strained layers, and, along with localized acceptor states, resonant states arise. The spectrum of terahertz radiation has been obtained, the current-voltage characteristics of the samples were investigated, and the energy spectra of acceptors were calculated. Peaks in the spontaneous emission spectrum correlate well with the results of the energy spectrum calculations. The transitions between the resonant and localized states of the acceptors make the main contribution to the terahertz radiation intensity.     

Electrochemical determination of synthetic antioxidants of bisdithiophosphonic acids

It has been found that bisdithiophosphonic acids with aryl substituents at the phosphorus atom quantitatively interact with electrogenerated halogens under the conditions of galvanostatic coulometry. Stoichiometric coefficients of the reaction between synthetic antioxidants and coulometric titrants-halogens have been determined. The corresponding reaction schemes have been proposed. The total antioxidant capacity (TAC) of the analytes has been estimated by their reaction with electrogenerated bromine. It has been demonstrated that bisdithiophosphonic acids bearing ionolic fragments demonstrate the highest TAC. It has been established that bisdithiophosphonic acids are irreversibly oxidized on a glassy carbon electrode at a potential of 800 mV with 0.1 M NaClO₄ in acetonitrile as the supporting electrolyte. The quantification limit and the analytical range of the analyte determination have been found.     

Monoterpenoids dithiophosphates. Synthesis and biological activity

O,O-Dialkyldithiophosphoric acids adds at the double bond of the racemic camphene and (+)- limonene in the presence of Lewis acids in accordance with the Markownikoff rule with the formation of Sterpenyl esters of dithiophosphoric acids. The reaction with camphene is accompanied by the rearrangement of camphane structure to that of bornane. Addition of dithiophosphoric acid to (+)-limonene proceeds with the participation of the exocyclic double bond. Toxic and genotoxic properties of the monoterpenoid dithiophosphates were studied.     

Cyclopropanation and epoxidation of 2-ylidene derivatives of lupane series

Russian Journal of Organic Chemistry - Crotone condensation of allobetulone with fluorine-containing benzaldehydes afforded new α,β-unsaturated ketones of lupane series. Their...     

Optimal Exercise Strategies for Operational Risk Insurance via Multiple Stopping Times

In this paper we demonstrate how to develop analytic closed form solutions to optimal multiple stopping time problems arising in the setting in which the value function acts on a compound process that is modified by the actions taken at the stopping times. This class of problem is particularly relevant in insurance and risk management settings and we demonstrate this on an important application domain based on insurance strategies in Operational Risk management for financial institutions. In this area of risk management the most prevalent class of loss process models is the Loss Distribution Approach (LDA) framework which involves modelling annual losses via a compound process. Given an LDA model framework, we consider Operational Risk insurance products that mitigate the risk for such loss processes and may reduce capital requirements. In particular, we consider insurance products that grant the policy holder the right to insure k of its annual Operational losses in a horizon of T years. We consider two insurance product structures and two general model settings, the first are families of relevant LDA loss models that we can obtain closed form optimal stopping rules for under each generic insurance mitigation structure and then secondly classes of LDA models for which we can develop closed form approximations of the optimal stopping rules. In particular, for losses following a compound Poisson process with jump size given by an Inverse-Gaussian distribution and two generic types of insurance mitigation, we are able to derive analytic expressions for the loss process modified by the insurance application, as well as closed form solutions for the optimal multiple stopping rules in discrete time (annually). When the combination of insurance mitigation and jump size distribution does not lead to tractable stopping rules we develop a principled class of closed form approximations to the optimal decision rule. These approximations are developed based on a class of orthogonal Askey polynomial series basis expansion representations of the annual loss compound process distribution and functions of this annual loss.     

Strength of single-layer and multilayer cylindrical vessels loaded internally by pulses of various lengths

Technological processes and experimental research involving the detonation of explosives must ensure the containment of the detonation products, the safety of personnel, and the protection of equipment. Frequently the test conditions impose rigid requirements on the size and weight of the vessels designed to localize the effect of pulsed loads of various kinds. Pressure vessels for operation under static loads, where the controlling parameter is the pressure, are commonly of multilayer construction. As a consequence of the stopping of cracks in the separate layers [1, 2] this construction can increase the level of the working pressure and avert the catastrophic rupture of the whole structure. It is of interest to investigate the behavior of multilayer shells under pulsed loads of various duration.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, pp. 152–58, September–October, 1978.