25 research outputs found
Soliton dynamics at an interface between uniform medium and nonlinear optical lattice
We study trapping and propagation of a matter-wave soliton through the
interface between uniform medium and a nonlinear optical lattice (NOL).
Different regimes for transmission of a broad and a narrow soliton are
investigated. Reflections and transmissions of solitons are predicted as
function of the lattice phase. The existence of a threshold in the amplitude of
the nonlinear optical lattice, separating the transmission and reflection
regimes, is verified. The localized nonlinear surface state, corresponding to
the soliton trapped by the interface, is found. Variational approach
predictions are confirmed by numerical simulations for the original
Gross-Pitaevskii equation with nonlinear periodic potentials
Collective excitations of BEC under anharmonic trap position jittering
Collective excitations of a Bose-Einstein condensate under periodic
oscillations of a quadratic plus quartic trap position has been studied. A
coupled set of variational equations is derived for the width and the
condensate wave function center. Analytical expressions for the growth of
oscillation amplitudes in the resonance case are derived. It is shown that
jittering of an anharmonic trap position can cause double resonance of the BEC
width and the center of mass oscillation in the wide range of the BEC
parameters values. The predictions of variational approach are confirmed by
full numerical simulations of the 1D GP equation.Comment: This paper contains a manuscript - SolAnJPB.tex and figures (fig1 -
fig1a.eps and fig1b.eps, fig2 - fig2.eps, fig3 - fig3a.eps and fig3b.eps,
fig4 - fig4a.eps and fig4b.eps). The manuscript has been prepared using
LATEX2e with the iopart class and the figures in encapsulated PostScrip
Effects of quantum fluctuations on macroscopic quantum tunneling and self-trapping of BEC in a double well trap
We study the influence of quantum fluctuations on the macroscopic quantum
tunneling and self-trapping of a two-component Bose-Einstein condensate in a
double-well trap. Quantum fluctuations are described by the Lee-Huang-Yang term
in the modified Gross-Pitaevskii equation. Employing the modified
Gross-Pitaevskii equation in scalar approximation, we derive the dimer model
using a two-mode approximation. The frequencies of Josephson oscillations and
self-trapping conditions under quantum fluctuations are found analytically and
proven by numerical simulations of the modified Gross-Pitaevskii equation. The
tunneling and localization phenomena are investigated also for the case of the
Lee-Huang-Yang fluid loaded in the double-well potential.Comment: 14 pages, 9 figure
Intoxication syndrome in patients with pulmonary tuberculosis in relation to the system glutathione transferase gene polymorphism
In 178 patients with different clinical forms of pulmonary tuberculosis carried out pharmacogenetic testing to determine gene polymorphism glutathione S-transferase system (GSTM1, GSTT1). Estimated the severity and duration of clinical manifestations of the syndrome of intoxication, depending on the gene polymorphism of glutathione S-transferase system (GSTM1, GSTT1). It was found that the combination of “zero” to develop genotypes GSTM1 and GSTT1 enzyme is a predictor of the severity and duration of symptoms of intoxication persisting
Resonances in a trapped 3D Bose-Einstein condensate under periodically varying atomic scattering length
Nonlinear oscillations of a 3D radial symmetric Bose-Einstein condensate
under periodic variation in time of the atomic scattering length have been
studied analytically and numerically. The time-dependent variational approach
is used for the analysis of the characteristics of nonlinear resonances in the
oscillations of the condensate. The bistability in oscillations of the BEC
width is invistigated. The dependence of the BEC collapse threshold on the
drive amplitude and parameters of the condensate and trap is found. Predictions
of the theory are confirmed by numerical simulations of the full
Gross-Pitaevski equation.Comment: 17 pages, 10 figures, submitted to Journal of Physics
Dynamics of bright matter wave solitons in a quasi 1D Bose-Einstein condensate with a rapidly varying trap
The dynamics of a bright matter wave soliton in a quasi 1D Bose-Einstein
condensate with periodically rapidly varying trap is considered. The governing
equation is derived based on averaging over fast modulations of the
Gross-Pitaevskii (GP) equation. This equation has the form of GP equation with
effective potential of more complicated structure than unperturbed trap. For
the case of inverted (expulsive) quadratic trap corresponding to unstable GP
equation, the effective potential can be stable. For the bounded in space trap
potential it is showed that the bifurcation exists, i.e.,the single well
potential bifurcates to the triple well effective potential. Stabilization of
BEC cloud on-site state in the temporary modulated optical lattice is found.
(analogous to the Kapitza stabilization of the pendulum). The predictions of
the averaged GP equation are confirmed by the numerical simulations of GP
equation with rapid perturbations.Comment: 15 pages, 4 figure
Collective oscillations of a quasi one dimensional Bose condensate under damping
Influence of the damping on collective oscillations of a one-dimensional
trapped Bose gas in the mean field regime has been studied. Using the
phenomenological damping approach developed by L.P. Pitaevskii, modified
variational equations for the parameters of the condensate wave function is
derived. Analytical expressions for the condensate parameters in equilibrium
state have been obtained. Bistability in nonlinear oscillations of the
condensate under periodic variations of the trap potential is predicted. The
predictions of the modified variational approach are confirmed by full
numerical simulations of the 1D GP equation with the damping.Comment: It contains a manuscript - damp1DBC.tex and figures (fig1a -
fig1a.eps, fig1b - fig1b.eps, fig2 - fig2.eps, fig3 - fig3.eps and fig4 -
fig4.eps
СИНДРОМ ИНТОКСИКАЦИИ У БОЛЬНЫХ ТУБЕРКУЛЕЗОМ ЛЕГКИХ В ЗАВИСИМОСТИ ОТ ПОЛИМОРФИЗМА ГЕНОВ СИСТЕМЫ ГЛУТАТИОНТРАНСФЕРАЗ
In 178 patients with different clinical forms of pulmonary tuberculosis carried out pharmacogenetic testing to determine gene polymorphism glutathione S-transferase system (GSTM1, GSTT1). Estimated the severity and duration of clinical manifestations of the syndrome of intoxication, depending on the gene polymorphism of glutathione S-transferase system (GSTM1, GSTT1). It was found that the combination of “zero” to develop genotypes GSTM1 and GSTT1 enzyme is a predictor of the severity and duration of symptoms of intoxication persisting.У 178 пациентов с различными клиническими формами туберкулеза легких выполнено фармакогенетическое тестирование для определения полиморфизма генов системы глутатионтрансфераз (GSTM1, GSTT1). Оценена выраженность и длительность клинических проявлений синдрома интоксикации в зависимости от полиморфизма генов системы глутатионтрансфераз (GSTM1, GSTT1). Установлено, что комбинация «нулевых» генотипов по выработке ферментов GSTM1 и GSTT1 является предиктором выраженных и длительно сохраняющихся симптомов интоксикации