Chaotic Diffusion on Periodic Orbits: The Perturbed Arnol'd Cat Map

Chaotic diffusion on periodic orbits (POs) is studied for the perturbed Arnol'd cat map on a cylinder, in a range of perturbation parameters corresponding to an extended structural-stability regime of the system on the torus. The diffusion coefficient is calculated using the following PO formulas: (a) The curvature expansion of the Ruelle zeta function. (b) The average of the PO winding-number squared, $w^{2}$, weighted by a stability factor. (c) The uniform (nonweighted) average of $w^{2}$. The results from formulas (a) and (b) agree very well with those obtained by standard methods, for all the perturbation parameters considered. Formula (c) gives reasonably accurate results for sufficiently small parameters corresponding also to cases of a considerably nonuniform hyperbolicity. This is due to {\em uniformity sum rules} satisfied by the PO Lyapunov eigenvalues at {\em fixed} $w$. These sum rules follow from general arguments and are supported by much numerical evidence.Comment: 6 Tables, 2 Figures (postscript); To appear in Physical Review

Direct multiplex imaging and optogenetics of Rho GTPases enabled by near-infrared FRET

Direct visualization and light control of several cellular processes is a challenge, owing to the spectral overlap of available genetically encoded probes. Here we report the most red-shifted monomeric near-infrared (NIR) fluorescent protein, miRFP720, and the fully NIR Forster resonance energy transfer (FRET) pair miRFP670-miRFP720, which together enabled design of biosensors compatible with CFP-YFP imaging and blue-green optogenetic tools. We developed a NIR biosensor for Rac1 GTPase and demonstrated its use in multiplexed imaging and light control of Rho GTPase signaling pathways. Specifically, we combined the Rac1 biosensor with CFP-YFP FRET biosensors for RhoA and for Rac1-GDI binding, and concurrently used the LOV-TRAP tool for upstream Rac1 activation. We directly observed and quantified antagonism between RhoA and Rac1 dependent on the RhoA-downstream effector ROCK; showed that Rac1 activity and GDI binding closely depend on the spatiotemporal coordination between these two molecules; and simultaneously observed Rac1 activity during optogenetic manipulation of Rac1.Peer reviewe

Modification of Vibrational Parameters of a CO₂ Molecule by a Laser Field: Impact on Tunnel Ionization

In this paper, we theoretically study the laser-induced modification of the vibrational parameters of a carbon dioxide molecule regarding its tunnel ionization. Our study predicts a 5% increase in the ionization rate in anti-Stokes channels that corresponds to pumping the Σu mode up to vai=10. The molecule is imparted with an additional energy from the pre-pumped vibrational states, which is absorbed during ionization. As a result, the tunneling rate increases. This amplification of tunnel ionization of the CO2 gas target can potentially be used for the laser separation of carbon isotopes

Modification of Vibrational Parameters of a <i>D</i>_∞<i>h</i>-Symmetric Triatomic Molecule in a Laser Plasma

We estimate theoretically the strong-field-modified vibrational parameters of three-atomic ABA molecules with D∞h symmetry in a laser-induced plasma. The linear CO2 and CS2 molecules in the X1Σg state are considered as examples. We show that double degeneracy of the Πu mode is removed due to reduction of the ABA molecule symmetry by the laser field. The linear form of ABA molecule is preserved, the bond length being elongated

Priešpaskutinio (vėlyvojo vidurinio pleistoceno) tarpledynmečio urano-torio izochroninio datavimo rezultatai Mardasavo pjūvio nuoguluose Lietuvoje

The Snaigupėlėe Interglacial gyttja was dated first by the uranium- thorium isochron method in the Mardasavas parastratotype section,. Southeastern Lithuania. The isochron-corrected 230Th / U ages are 202.4 + 38.6/-22.9 ka (TSD method) and 220.6 + 35.3 / 20.5 ka (L/L method). Theses dates correspond to the second part of the Interglacial. The range of the obtained ages is close to the age limit of the MOIS 7 stage of deep sea sediments (186-242 ka). The 230Th / U dates obtained on gyttja from the Mardasavas section are in fact the corresponding deposits of the penultimate (Snaigupėlė) Interglacial within MOIS 7 present in Lithuania. One more Interglacial warming (Snaigupėlė = Drenthe-Wartha - Cherepet) is recognized between the Butėnai = Holsteinian = Likhvinian Interglacial of the Middle Pleistocene and the Merkine = Eemian = Mikulino = Kazantsovian Interglacial of the Late Pleistocene. The warm climate event of MOIS 7 is of broad transcontinental or even hemispheral significance rather than a local phenomenon in the Last European Plain

Absolute Double-Differential Cross Sections of Ultrasoft Isochromatic X-ray Radiation in Electron Scattering on Atoms

We calculate double-differential cross sections of ultrasoft X-ray bremsstrahlung in electron scattering by Ar, Kr, and Xe atoms in the soft-photon approximation. The calculations are done for the isochromatic spectra (i.e., dependence on the electron energy at a fixed photon energy of 165 and 177 eV). The results are consistent with the absolute values of the differential cross sections measured by Gnatchenko et al. (Phys. Rev. A 80, 022707 (2009)) for the above-mentioned photon energies. For low electron energies, our theoretical isochromatic spectra are in quantitative agreement with the experimental data for Ar. For Kr, the agreement is qualitative while agreement with the Xe data is poor

Absolute Double-Differential Cross Sections of Ultrasoft Isochromatic X-ray Radiation in Electron Scattering on Atoms

We calculate double-differential cross sections of ultrasoft X-ray bremsstrahlung in electron scattering by Ar, Kr, and Xe atoms in the soft-photon approximation. The calculations are done for the isochromatic spectra (i.e., dependence on the electron energy at a fixed photon energy of 165 and 177 eV). The results are consistent with the absolute values of the differential cross sections measured by Gnatchenko et al. (Phys. Rev. A 80, 022707 (2009)) for the above-mentioned photon energies. For low electron energies, our theoretical isochromatic spectra are in quantitative agreement with the experimental data for Ar. For Kr, the agreement is qualitative while agreement with the Xe data is poor