Synthesis of novel pyrimidine nucleoside analogues

Two new tetrazolopyrimidinedeoxynucleosides were synthesized and their physico-chemical data are described. Results of preliminary analyses of their biological properties are also reported.     

Hardy inequalities related to Grushin type operators

We prove some Hardy type inequalities related to the Grushin type operator .

     

On the Possibility of Testing the Weak Equivalence Principle with Artificial Earth Satellites

In this paper we examine the possibility of testing the equivalence principle, in its weak form, by analyzing the orbital motion of a pair of artificial satellites of different composition moving along orbits of identical shape and size in the gravitational field of the Earth. It turns out that the obtainable level of accuracy is, realistically, of the order of 10^–10 or slightly better. It is limited mainly by the fact that, due to the unavoidable orbital injection errors, it would not be possible to insert the satellites in orbits with exactly the same radius and that such difference could be known only with a finite precision. The present–day level of accuracy, obtained with torsion balance Earth–based measurements and the analysis of the Earth–Moon motion in the gravitational field of the Sun with the Lunar Laser Ranging technique, is of the order of 10^–13. The proposed space–based missions STEP, SCOPE, GG and SEE aim to reach a 10^–15–10^–18 precision level.     

Oort's conjecture for

We prove the conjecture of Oort that a compact subvariety of the moduli space of principally polarized Abelian varieties of genus has codimension strictly greater than , in characteristic zero, for .

     

Letter: A Reassessment of the Systematic Gravitational Error in the LARES Mission

In this letter we reexamine the evaluation of the error due to the even zonal harmonics of the geopotential in some proposed tests of relativistic gravitomagnetism with existing and proposed laser–ranged LAGEOS–like satellites in the gravitational field of the Earth. It is particularly important because the error due to the even zonal harmonics of the geopotential is one of the major sources of systematic errors in this kind of measurements. A conservative, although maybe pessimistic, approach is followed by using the diagonal part only of the covariance matrix of the EGM96 Earth's gravity model up to degree l = 20. It turns out that, within this context and according to the present level of knowledge of the terrestrial gravitational field, the best choice would be the use of a recently proposed combination which involves the nodes of LAGEOS, LAGEOS II and LARES and the perigees of LAGEOS II and LARES. Indeed, it turns out that the unavoidable orbital injection errors in the inclination of LARES would not affect the gravitational error which would also be insensitive to the correlations among the even zonal harmonics of geopotential.     

Micro-transitions or breathers in L-alanine?

Within mean field approximation, a procedure is elaborated to consider noise induced phase transitions with arbitrary relations between the noises of different degrees of freedom. The proposed approach is applied to investigate effects of cross correlation between noises in the generalized synergetic model of Lorenz type. This cross correlation is shown to induce phase transitions of the dynamical system under consideration. Additionally, we find the correlation between noises transforms a synergetic behavior to a thermodynamic one. Received 13 November 2002 Published online 11 April 2003 RID="a" ID="a"e-mail: dikh@sumdu.edu.ua     

Nontrivial fixed point in a twofold orbitally degenerate Anderson impurity model

We study a twofold orbitally degenerate Anderson impurity model which shows a nontrivial fixed point similar to that of the two-impurity Kondo model, but remarkably more robust, as it can only be destabilized by orbital- or gauge-symmetry breaking. The impurity model is interesting per se, but here our interest is rather in the possibility that it might be representative of a strongly correlated lattice model close to a Mott transition. We argue that this lattice model should unavoidably encounter the nontrivial fixed point just before the Mott transition and react to its instability by spontaneous generation of an orbital, spin-orbital or superconducting order parameter.     

Entanglement assisted capacity of the broadband Lossy channel

We calculate the entanglement assisted capacity of a multimode bosonic channel with loss. As long as the efficiency of the channel is above 50%, the superdense coding effect can be used to transmit more bits than those that can be stored in the message sent down the channel. Bounds for the other capacities of the multimode channel are also provided.     

Oxidative diphosphonylation of 1,4-dihydropyridines and pyridinium salts

An oxidative double phosphonylation of dihydropyridines 1 and pyridinium salts 2 is achieved through the use of dialkyl phosphites, DDQ, and triethylamine. Acceptable to good yields of 2, 6-diphosphonylated-1,2-dihydropyridines 3 are obtained in a one-pot reaction involving tandem nucleophilic addition/oxidation processes. Isomerization of 3 to the more stable 2,4-diphosphonylated-1, 4-dihydropyridine 4 was observed in some cases.