11 research outputs found
Two-photon driven nonlinear dynamics and entanglement of an atom in a non uniform cavity
In this paper we study the dynamics in the general case for a Tavis Cummings
atom in a non-uniform cavity. In addition to the dynamical Stark shift, the
center-of-mass motion of the atom and the recoil effect are considered in both
- the weak and the strong cavity atom coupling regimes. It is shown that the
spatial motion of the atom inside the cavity in the resonant case leads to a
transition between topologically different solutions. This effect is manifested
by a singularity in the inter-level transition spectrum. In the non-resonant
case, the spatial motion of the atom leads to a switching of the spin
orientation. In both effects, the key factor is the relation between the values
of the Stark shift and the cavity field coupling constant. We also investigate
the entanglement of an atom in the cavity with the radiation field. It is shown
that the entanglement between the atom and the field, usually quantified in
terms of purity, decreases with increasing the Stark shift.Comment: to appear in Phys. Rev.
Silencing Agrobacterium oncogenes in transgenic grapevine results in strain-specific crown gall resistance
Crown gall disease of grapevine induced by Agrobacterium vitis or Agrobacterium tumefaciens causes serious
economic losses in viticulture. To establish crown gall-resistant lines, somatic proembryos of Vitis
berlandieri Ă— V. rupestris cv. 'Richter 110' rootstock were transformed with an oncogene-silencing transgene
based on iaaM and ipt oncogene sequences from octopine-type, tumor-inducing (Ti) plasmid pTiA6. Twentyone
transgenic lines were selected, and their transgenic nature was confirmed by polymerase chain reaction
(PCR). These lines were inoculated with two A. tumefaciens and three A. vitis strains. Eight lines showed
resistance to octopine-type A. tumefaciens A348. Resistance correlated with the expression of the silencing
genes. However, oncogene silencing was mostly sequence specific because these lines did not abolish
tumorigenesis by A. vitis strains or nopaline-type A. tumefaciens C58