111 research outputs found
On-site number statistics of ultracold lattice bosons
We study on-site occupation number fluctuations in a system of interacting
bosons in an optical lattice. The ground-state distribution is obtained
analytically in the limiting cases of strong and weak interaction, and by means
of exact Monte Carlo simulations in the strongly correlated regime. As the
interaction is increased, the distribution evolves from Poissonian in the
non-interacting gas to a sharply peaked distribution in the Mott-insulator (MI)
regime. In the special case of large occupation numbers, we demonstrate
analytically and check numerically that there exists a wide interval of
interaction strength, in which the on-site number fluctuations remain Gaussian
and are gradually squeezed until they are of order unity near the superfluid
(SF)-MI transition. Recently, the on-site number statistics were studied
experimentally in a wide range of lattice potential depths [Phys. Rev. Lett.
\textbf{96}, 090401 (2006)]. In our simulations, we are able to directly
reproduce experimental conditions using temperature as the only free parameter.
Pronounced temperature dependence suggests that measurements of on-site atom
number fluctuations can be employed as a reliable method of thermometry in both
SF and MI regimes.Comment: 9 pages, 4 figure
Fluctuating and dissipative dynamics of dark solitons in quasi-condensates
The fluctuating and dissipative dynamics of matter-wave dark solitons within
harmonically trapped, partially condensed Bose gases is studied both
numerically and analytically. A study of the stochastic Gross-Pitaevskii
equation, which correctly accounts for density and phase fluctuations at finite
temperatures, reveals dark soliton decay times to be lognormally distributed at
each temperature, thereby characterizing the previously predicted long lived
soliton trajectories within each ensemble of numerical realizations (S.P.
Cockburn {\it et al.}, Phys. Rev. Lett. 104, 174101 (2010)). Expectation values
for the average soliton lifetimes extracted from these distributions are found
to agree well with both numerical and analytic predictions based upon the
dissipative Gross-Pitaevskii model (with the same {\it ab initio} damping).
Probing the regime for which , we find average
soliton lifetimes to scale with temperature as , in agreement
with predictions previously made for the low-temperature regime .
The model is also shown to capture the experimentally-relevant decrease in the
visibility of an oscillating soliton due to the presence of background
fluctuations.Comment: 17 pages, 14 figure
Differential approximation for Kelvin-wave turbulence
I present a nonlinear differential equation model (DAM) for the spectrum of
Kelvin waves on a thin vortex filament. This model preserves the original
scaling of the six-wave kinetic equation, its direct and inverse cascade
solutions, as well as the thermodynamic equilibrium spectra. Further, I extend
DAM to include the effect of sound radiation by Kelvin waves. I show that,
because of the phonon radiation, the turbulence spectrum ends at a maximum
frequency where
is the total energy injection rate, is the speed of sound and
is the quantum of circulation.Comment: Prepared of publication in JETP Letter
ΠΠ΅Π»ΡΠ½ΠΎΠΊΠ°ΠΌΠ΅Π½Π½Π°Ρ Π±ΠΎΠ»Π΅Π·Π½Ρ ΡΡΠ΅Π΄ΠΈ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΎΠ³ΠΎ ΠΏΠ΅ΡΡΠΎΠ½Π°Π»Π° ΠΏΠΎΠ»ΠΈΠΊΠ»ΠΈΠ½ΠΈΠΊΠΈ: ΡΠ°ΠΊΡΠΎΡΡ ΡΠΈΡΠΊΠ° Π΅Π΅ ΡΠ°Π·Π²ΠΈΡΠΈΡ Π² ΡΠ°Π·Π½ΡΡ ΠΏΡΠΎΡΠ΅ΡΡΠΈΠΎΠ½Π°Π»ΡΠ½ΡΡ Π³ΡΡΠΏΠΏΠ°Ρ
The aim. Identification of risk factors for gallstone disease (GDS) development between different professional groups of polyclinic medical staff. Material and methods. 75 medical staff members were divided into two groups (1st group: 30 doctors; 2nd group: 45 nurses). All of them were interviewed fo r information about profession, gender, age, waist circumference (WC), body mass index (BMI), smoking, arterial hypertension (AH), diabetes mellitus (DM) and hypercholesterolemia. In addition, women were interviewed about the number of pregnancies, ostmenopause and taking oral contraceptive pills (OCPs). To assess physical activity, a short international questionnaire on physical activity (IPAQ) was used. To identify the presence of professional burnout (PB) syndrome we applied the Maslach Burnout Inventory (MBI) questionnaire, adapted by N.Π. Vodopianova for medical staff. At the final stage, the data of abdominal organs ultrasound examination were analyzed based on the materials of medical staff outpatient records. Results. The GSD prevalence among doctors was 33.3%, and 24.4% among nurses. In both groups age, AH, weight, WC and BMI contribute to GSD formation. In the first group of individuals with GSD, the level of total cholesterol (TC) was significantly higher. In the same group extremely high PB, postmenopause (p <0.05) and hypodynamia (p <0.1) were much more common. In the second group, there were more DM cases and pregnancies (p <0.05). Conclusion. The medical staff of the clinic has a high GSD incidence, whose frequency depends not only on classical risk factors prevalence, but is also determined by profession peculiarities, characterized by high psychological stress and lower physical activity of physicians, compared to nurses.Π¦Π΅Π»Ρ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ. ΠΡΡΠ²ΠΈΡΡ ΡΠ°ΠΊΡΠΎΡΡ ΡΠΈΡΠΊΠ° ΡΠ°Π·Π²ΠΈΡΠΈΡ ΠΆΠ΅Π»ΡΠ½ΠΎΠΊΠ°ΠΌΠ΅Π½Π½ΠΎΠΉ Π±ΠΎΠ»Π΅Π·Π½ΠΈ (ΠΠΠ) ΡΡΠ΅Π΄ΠΈ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΎΠ³ΠΎ ΠΏΠ΅ΡΡΠΎΠ½Π°Π»Π° ΠΏΠΎΠ»ΠΈΠΊΠ»ΠΈΠ½ΠΈΠΊΠΈ Π² ΡΠ°Π·Π½ΡΡ
ΠΏΡΠΎΡΠ΅ΡΡΠΈΠΎΠ½Π°Π»ΡΠ½ΡΡ
Π³ΡΡΠΏΠΏΠ°Ρ
. ΠΠ°ΡΠ΅ΡΠΈΠ°Π»Ρ ΠΈ ΠΌΠ΅ΡΠΎΠ΄Ρ. Π ΠΏΠΎΠ»ΠΈΠΊΠ»ΠΈΠ½ΠΈΠΊΠ΅ Π±ΡΠ»ΠΎ ΠΎΡΠΌΠΎΡΡΠ΅Π½ΠΎ ΠΈ Π°Π½ΠΊΠ΅ΡΠΈΡΠΎΠ²Π°Π½ΠΎ 75 ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΡ
ΡΠΎΡΡΡΠ΄Π½ΠΈΠΊΠΎΠ² ΠΏΠΎΠ»ΠΈΠΊΠ»ΠΈΠ½ΠΈΠΊΠΈ, ΠΊΠΎΡΠΎΡΡΠ΅ Π±ΡΠ»ΠΈ ΡΠ°Π·Π΄Π΅Π»Π΅Π½Ρ Π½Π° Π΄Π²Π΅ Π³ΡΡΠΏΠΏΡ. Π 1-Ρ Π±ΡΠ»ΠΈ Π²ΠΊΠ»ΡΡΠ΅Π½Ρ 30 Π²ΡΠ°ΡΠ΅ΠΉ; Π²ΠΎ 2-Ρ - 45 ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΡ
ΡΠ΅ΡΡΠ΅Ρ. ΠΠ½Π°Π»ΠΈΠ·Ρ ΠΏΠΎΠ΄Π²Π΅ΡΠ³Π°Π»ΠΈΡΡ ΡΠ°ΠΊΠΈΠ΅ ΠΏΠΎΠΊΠ°Π·Π°ΡΠ΅Π»ΠΈ, ΠΊΠ°ΠΊ ΠΏΡΠΎΡΠ΅ΡΡΠΈΡ, ΠΏΠΎΠ», Π²ΠΎΠ·ΡΠ°ΡΡ, ΠΎΠ±ΡΠ΅ΠΌ ΡΠ°Π»ΠΈΠΈ (ΠΠ’), ΠΈΠ½Π΄Π΅ΠΊΡ ΠΌΠ°ΡΡΡ ΡΠ΅Π»Π° (ΠΠΠ’), ΠΊΡΡΠ΅Π½ΠΈΠ΅, Π½Π°Π»ΠΈΡΠΈΠ΅ Π°ΡΡΠ΅ΡΠΈΠ°Π»ΡΠ½ΠΎΠΉ Π³ΠΈΠΏΠ΅ΡΡΠ΅Π½Π·ΠΈΠΈ (ΠΠ), ΡΠ°Ρ
Π°ΡΠ½ΠΎΠ³ΠΎ Π΄ΠΈΠ°Π±Π΅ΡΠ° (Π‘Π), Π³ΠΈΠΏΠ΅ΡΡ
ΠΎΠ»Π΅ΡΡΠ΅ΡΠΈΠ½Π΅ΠΌΠΈΠΈ, ΠΏΠΎΡΡΠΌΠ΅Π½ΠΎΠΏΠ°ΡΠ·Ρ; Ρ ΠΆΠ΅Π½ΡΠΈΠ½ β ΠΊΠΎΠ»ΠΈΡΠ΅ΡΡΠ²ΠΎ Π±Π΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΡΡΠ΅ΠΉ ΠΈ ΠΏΡΠΈΠ΅ΠΌ ΠΎΡΠ°Π»ΡΠ½ΡΡ
ΠΊΠΎΠ½ΡΡΠ°ΡΠ΅ΠΏΡΠΈΠ²ΠΎΠ² (ΠΠ). ΠΠ»Ρ ΠΎΡΠ΅Π½ΠΊΠΈ ΡΠΈΠ·ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ ΠΏΡΠΈΠΌΠ΅Π½ΡΠ»ΠΈ ΠΊΡΠ°ΡΠΊΠΈΠΉ ΠΌΠ΅ΠΆΠ΄ΡΠ½Π°ΡΠΎΠ΄Π½ΡΠΉ ΠΎΠΏΡΠΎΡΠ½ΠΈΠΊ ΠΏΠΎ ΡΠΈΠ·ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΠΈ (IPAQ). ΠΠ»Ρ Π²ΡΡΠ²Π»Π΅Π½ΠΈΡ ΡΠΈΠΌΠΏΡΠΎΠΌΠΎΠ² ΠΏΡΠΎΡΠ΅ΡΡΠΈΠΎΠ½Π°Π»ΡΠ½ΠΎΠ³ΠΎ Π²ΡΠ³ΠΎΡΠ°Π½ΠΈΡ (ΠΠ) ΠΈΡΠΏΠΎΠ»ΡΠ·ΠΎΠ²Π°Π»ΠΈ ΠΎΠΏΡΠΎΡΠ½ΠΈΠΊ Maslach Burnout Inventory (MBI), Π°Π΄Π°ΠΏΡΠΈΡΠΎΠ²Π°Π½Π½ΡΠΉ Π.Π. ΠΠΎΠ΄ΠΎΠΏΡΡΠ½ΠΎΠ²ΠΎΠΉ Π΄Π»Ρ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΡ
ΡΠΎΡΡΡΠ΄Π½ΠΈΠΊΠΎΠ². ΠΠ° ΠΊΠΎΠ½Π΅ΡΠ½ΠΎΠΌ ΡΡΠ°ΠΏΠ΅ Π°Π½Π°Π»ΠΈΠ·ΠΈΡΠΎΠ²Π°Π»ΠΈΡΡ Π΄Π°Π½Π½ΡΠ΅ ΡΠ»ΡΡΡΠ°Π·Π²ΡΠΊΠΎΠ²ΠΎΠ³ΠΎ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΎΡΠ³Π°Π½ΠΎΠ² Π±ΡΡΡΠ½ΠΎΠΉ ΠΏΠΎΠ»ΠΎΡΡΠΈ ΠΏΠΎ Π°ΠΌΠ±ΡΠ»Π°ΡΠΎΡΠ½ΡΠΌ ΠΊΠ°ΡΡΠ°ΠΌ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΡ
ΡΠ°Π±ΠΎΡΠ½ΠΈΠΊΠΎΠ². Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. Π Π°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½Π½ΠΎΡΡΡ ΠΠΠ ΡΡΠ΅Π΄ΠΈ Π²ΡΠ°ΡΠ΅ΠΉ ΡΠΎΡΡΠ°Π²ΠΈΠ»Π° 33,3%, ΠΈ 24,4% ΡΡΠ΅Π΄ΠΈ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΡ
ΡΠ΅ΡΡΠ΅Ρ. Π ΠΎΠ±Π΅ΠΈΡ
Π³ΡΡΠΏΠΏΠ°Ρ
Π½Π° ΡΠΎΡΠΌΠΈΡΠΎΠ²Π°Π½ΠΈΠ΅ ΠΠΠ Π²Π»ΠΈΡΡΡ Π²ΠΎΠ·ΡΠ°ΡΡ, Π½Π°Π»ΠΈΡΠΈΠ΅ ΠΠ, Π²Π΅Ρ, ΠΠ’, ΠΠΠ’. Π ΠΏΠ΅ΡΠ²ΠΎΠΉ Π³ΡΡΠΏΠΏΠ΅ Π»ΠΈΡ Ρ ΠΠΠ ΡΡΠΎΠ²Π΅Π½Ρ ΠΎΠ±ΡΠ΅Π³ΠΎ Ρ
ΠΎΠ»Π΅ΡΡΠ΅ΡΠΈΠ½Π° Π±ΡΠ» Π΄ΠΎΡΡΠΎΠ²Π΅ΡΠ½ΠΎ Π²ΡΡΠ΅ (ΠΠ₯). Π ΡΡΠΎΠΉ ΠΆΠ΅ Π³ΡΡΠΏΠΏΠ΅ ΠΠ ΠΊΡΠ°ΠΉΠ½Π΅ Π²ΡΡΠΎΠΊΠΎΠΉ ΡΡΠ΅ΠΏΠ΅Π½ΠΈ, ΠΏΠΎΡΡΠΌΠ΅Π½ΠΎΠΏΠ°ΡΠ·Π° (p<0,05) ΠΈ Π³ΠΈΠΏΠΎΠ΄ΠΈΠ½Π°ΠΌΠΈΡ (p<0,1) Π²ΡΡΡΠ΅ΡΠ°Π»ΠΈΡΡ Π·Π½Π°ΡΠΈΡΠ΅Π»ΡΠ½ΠΎ ΡΠ°ΡΠ΅. Π Π³ΡΡΠΏΠΏΠ΅ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΡ
ΡΠ΅ΡΡΠ΅Ρ Ρ ΠΠΠ ΠΎΡΠΌΠ΅ΡΠ°Π»ΠΎΡΡ ΠΏΡΠ΅ΠΎΠ±Π»Π°Π΄Π°Π½ΠΈΠ΅ Π»ΠΈΡ Ρ Π‘Π ΠΈ Π±ΠΎΠ»ΡΡΠ΅Π΅ ΡΠΈΡΠ»ΠΎ Π±Π΅ΡΠ΅ΠΌΠ΅Π½Π½ΠΎΡΡΠ΅ΠΉ (p<0,05). ΠΠ°ΠΊΠ»ΡΡΠ΅Π½ΠΈΠ΅. Π£ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΎΠ³ΠΎ ΠΏΠ΅ΡΡΠΎΠ½Π°Π»Π° ΠΏΠΎΠ»ΠΈΠΊΠ»ΠΈΠ½ΠΈΠΊΠΈ ΠΈΠΌΠ΅Π΅Ρ ΠΌΠ΅ΡΡΠΎ Π²ΡΡΠΎΠΊΠ°Ρ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½Π½ΠΎΡΡΡ ΠΠΠ, ΡΠ°ΡΡΠΎΡΠ° ΠΊΠΎΡΠΎΡΠΎΠΉ Π·Π°Π²ΠΈΡΠΈΡ Π½Π΅ ΡΠΎΠ»ΡΠΊΠΎ ΠΎΡ ΡΠ°ΡΠΏΡΠΎΡΡΡΠ°Π½Π΅Π½Π½ΠΎΡΡΠΈ ΠΊΠ»Π°ΡΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠ°ΠΊΡΠΎΡΠΎΠ² ΡΠΈΡΠΊΠ°, Π½ΠΎ ΠΈ ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΡΡΡ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΡΠΌΠΈ ΠΏΡΠΎΡΠ΅ΡΡΠΈΠΎΠ½Π°Π»ΡΠ½ΠΎΠΉ Π΄Π΅ΡΡΠ΅Π»ΡΠ½ΠΎΡΡΠΈ, Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΡΡΠ΅ΠΉΡΡ Π²ΡΡΠΎΠΊΠΎΠΉ ΠΏΡΠΈΡ
ΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π½Π°Π³ΡΡΠ·ΠΊΠΎΠΉ ΠΈ Π±ΠΎΠ»Π΅Π΅ Π½ΠΈΠ·ΠΊΠΎΠΉ ΡΠΈΠ·ΠΈΡΠ΅ΡΠΊΠΎΠΉ Π°ΠΊΡΠΈΠ²Π½ΠΎΡΡΡΡ Π²ΡΠ°ΡΠ΅Π±Π½ΠΎΠ³ΠΎ ΠΏΠ΅ΡΡΠΎΠ½Π°Π»Π°, ΠΏΠΎ ΡΡΠ°Π²Π½Π΅Π½ΠΈΡ Ρ ΠΌΠ΅Π΄ΠΈΡΠΈΠ½ΡΠΊΠΈΠΌΠΈ ΡΠ΅ΡΡΡΠ°ΠΌΠΈ
Decay of quantised vorticity by sound emission
It is thought that in a quantum fluid sound generation is the ultimate sink
of turbulent kinetic energy in the absence of any other dissipation mechanism
near absolute zero. We show that a suitably trapped Bose-Einstein condensate
provides a model system to study the sound emitted by accelerating vortices in
a controlled way.Comment: 6 pages, 3 figure
Ultracold Dipolar Gases in Optical Lattices
This tutorial is a theoretical work, in which we study the physics of
ultra-cold dipolar bosonic gases in optical lattices. Such gases consist of
bosonic atoms or molecules that interact via dipolar forces, and that are
cooled below the quantum degeneracy temperature, typically in the nK range.
When such a degenerate quantum gas is loaded into an optical lattice produced
by standing waves of laser light, new kinds of physical phenomena occur. These
systems realize then extended Hubbard-type models, and can be brought to a
strongly correlated regime. The physical properties of such gases, dominated by
the long-range, anisotropic dipole-dipole interactions, are discussed using the
mean-field approximations, and exact Quantum Monte Carlo techniques (the Worm
algorithm).Comment: 56 pages, 26 figure
Phase diagram of two-component bosons on an optical lattice
We present a theoretical analysis of the phase diagram of two--component
bosons on an optical lattice. A new formalism is developed which treats the
effective spin interactions in the Mott and superfluid phases on the same
footing. Using the new approach we chart the phase boundaries of the broken
spin symmetry states up to the Mott to superfluid transition and beyond. Near
the transition point, the magnitude of spin exchange can be very large, which
facilitates the experimental realization of spin-ordered states. We find that
spin and quantum fluctuations have a dramatic effect on the transition making
it first order in extended regions of the phase diagram. For Mott states with
even occupation we find that the competition between effective Heisenberg
exchange and spin-dependent on--site interaction leads to an additional phase
transition from a Mott insulator with no broken symmetries into a spin-ordered
insulator
The approach to vortex reconnection
We present numerical solutions of the Gross--Pitaevskii equation
corresponding to reconnecting vortex lines. We determine the separation of
vortices as a function of time during the approach to reconnection, and study
the formation of pyramidal vortex structures. Results are compared with
analytical work and numerical studies based on the vortex filament method.Comment: 11 pages, 9 figure
Identification of Kelvin waves: numerical challenges
Kelvin waves are expected to play an essential role in the energy dissipation
for quantized vortices. However, the identification of these helical
distortions is not straightforward, especially in case of vortex tangle. Here
we review several numerical methods that have been used to identify Kelvin
waves within the vortex filament model. We test their validity using several
examples and estimate whether these methods are accurate enough to verify the
correct Kelvin spectrum. We also illustrate how the correlation dimension is
related to different Kelvin spectra and remind that the 3D energy spectrum E(k)
takes the form 1/k in the high-k region, even in the presence of Kelvin waves.Comment: 6 pages, 5 figures. The final publication is available at
http://www.springerlink.co
Influence of nearly resonant light on the scattering length in low-temperature atomic gases
We develop the idea of manipulating the scattering length in
low-temperature atomic gases by using nearly resonant light. As found, if the
incident light is close to resonance with one of the bound levels of
electronically excited molecule, then virtual radiative transitions of a pair
of interacting atoms to this level can significantly change the value and even
reverse the sign of . The decay of the gas due to photon recoil, resulting
from the scattering of light by single atoms, and due to photoassociation can
be minimized by selecting the frequency detuning and the Rabi frequency. Our
calculations show the feasibility of optical manipulations of trapped Bose
condensates through a light-induced change in the mean field interaction
between atoms, which is illustrated for Li.Comment: 12 pages, 1 Postscript figur
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