The role of the neural crest in the normal and abnormal heart development

The data about participation of the neural crest in the normal and abnormal cardiogenesis are summarized in the review. The main morphological phenomena which accompany the interaction of the neural crest cells and embryonic heart are the migration of the dense mesenchyme originated from neural crest from pharyngeal arches to the trunk of heart as well as apoptotic processes. After chemical teratogens treatment such as retinoic acid and ethyl alcohol the distant relationship between neural crest and heart and also the migration of neural crest cells to the heart were changed. The decrease of inten-sity of the apoptotic processes in the heart, the delay of reduction of the conotruncal and atrioventricular myocardium and lesion of mesenchyme structures were determined morphologically. The ethanol and retinoic acid treatment cause also the abnormalities in the interventricular foramen closure, in the development of conductive system, and heart valves. We suggest that these abnormalities are mediated by the neural crest cells

E1 amplitudes, lifetimes, and polarizabilities of the low-lying levels of atomic ytterbium

The results of ab initio calculation of E1 amplitudes, lifetimes,and polarizabilities for several low-lying levels of ytterbium are reported. The effective Hamiltonian for the valence electrons has been constructed in the frame of CI+MBPT method and solutions of many electron equation are found.Comment: 11 pages, submitted to Phys.Rev.

Closed Abrikosov Vortices in a Superconducting Cylinder

The new type of solutions of the London equation for type-II superconductors is obtained to describe the ring-shaped (toroidal) Abrikosov vortices. The specific feature of these solutions is the self-consistent localization of both the supercurrent and the magnetic field, enabling one to construct compact magnetic structures inside a superconductor. The torus vortex contraction caused by the vortex instability leads to the destruction of the Cooper pairing and the formation of a normal electron stream in the vicinity of the torus axis. The thermodynamic condition for the excitation of a small closed vortex by a bunch of charged particles contains the fine-structure constant as a determining parameter.Comment: LaTex using revtex, 12 pages. 5 Figures available upon request from [email protected] Accepted for publication in Physica

Electric dipole moments of Hg, Xe, Rn, Ra, Pu, and TlF induced by the nuclear Schiff moment and limits on time-reversal violating interactions

We have calculated the atomic electric dipole moments (EDMs) induced in ^{199}Hg, ^{129}Xe, ^{223}Rn, ^{225}Ra, and ^{239}Pu by their respective nuclear Schiff moments S. The results are (in units 10^{-17}S(e {fm}^{3})^{-1}e cm): d(^{199}Hg)=-2.8, d(^{129}Xe)=0.38, d(^{223}Rn)=3.3, d(^{225}Ra)=-8.5, d(^{239}Pu)=-11. We have also calculated corrections to the parity- and time-invariance-violating (P,T-odd) spin-axis interaction constant in TlF. These results are important for the interpretation of atomic and molecular experiments on EDMs in terms of fundamental P,T-odd parameters.Comment: 16 page

Calculation of nuclear spin-dependent parity-nonconserving amplitude for (7s,F=4) --> (7s,F=5) transition in Fr

Many-body calculation of nuclear spin-dependent parity-nonconserving amplitude for (7s,F=4) --> (7s,F=5) transition between hyperfine sublevels of the ground state of $^{211}$Fr is carried out. The final result is <7s,F=5 ||d_PNC|| 7s,F=4> = -0.49 10^{-10} i kappa a.u., where kappa is the dimensionless coupling constant. This is approximately an order of magnitude larger than similar amplitude in Cs. The dominant contribution to kappa is associated with the anapole moment of the nucleus.Comment: 4 pages, submitted to Phys.Rev.

Measurement of the 6s - 7p transition probabilities in atomic cesium and a revised value for the weak charge Q_W

We have measured the 6s - 7p_{1/2,3/2} transition probabilities in atomic cesium using a direct absorption technique. We use our result plus other previously measured transition rates to derive an accurate value of the vector transition polarizability \beta and, consequently, re-evaluate the weak charge Q_W. Our derived value Q_W=-72.65(49) agrees with the prediction of the standard model to within one standard deviation.Comment: 4 pages, 2 figure

Reevaluation of the role of nuclear uncertainties in experiments on atomic parity violation with isotopic chains

In light of new data on neutron distributions from experiments with antiprotonic atoms [ Trzcinska {\it et al.}, Phys. Rev. Lett. 87, 082501 (2001)], we reexamine the role of nuclear-structure uncertainties in the interpretation of measurements of parity violation in atoms using chains of isotopes of the same element. With these new nuclear data, we find an improvement in the sensitivity of isotopic chain measurements to ``new physics'' beyond the standard model. We compare possible constraints on ``new physics'' with the most accurate to date single-isotope probe of parity violation in the Cs atom. We conclude that presently isotopic chain experiments employing atoms with nuclear charges Z < 50 may result in more accurate tests of the weak interaction.Comment: 6 pages, 1 fig., submitted to Phys. Rev.

Parity nonconservation in heavy atoms: The radiative correction enhanced by the strong electric field of the nucleus

Parity nonconservation due to the nuclear weak charge is considered. We demonstrate that the radiative corrections to this effect due to the vacuum fluctuations of the characteristic size larger than the nuclear radius $r_0$ and smaller than the electron Compton wave-length $\lambda_C$ are enhanced because of the strong electric field of the nucleus. The parameter that allows one to classify the corrections is the large logarithm $\ln(\lambda_C/r_0)$. The vacuum polarization contribution is enhanced by the second power of the logarithm. Although the self-energy and the vertex corrections do not vanish, they contain only the first power of the logarithm. The value of the radiative correction is 0.4% for Cs and 0.9% for Tl, Pb, and Bi. We discuss also how the correction affects the interpretation of the experimental data on parity nonconservation in atoms.Comment: 4 pages, 3 figures, RevTe