359 research outputs found
Imaging a single atom in a time-of-flight experiment
We perform fluorescence imaging of a single 87Rb atom after its release from
an optical dipole trap. The time-of-flight expansion of the atomic spatial
density distribution is observed by accumulating many single atom images. The
position of the atom is revealed with a spatial resolution close to 1
micrometer by a single photon event, induced by a short resonant probe. The
expansion yields a measure of the temperature of a single atom, which is in
very good agreement with the value obtained by an independent measurement based
on a release-and-recapture method. The analysis presented in this paper
provides a way of calibrating an imaging system useful for experimental studies
involving a few atoms confined in a dipole trap.Comment: 14 pages, 8 figure
Tilivalline- and Tilimycin-Independent Effects of Klebsiella oxytoca on Tight Junction-Mediated Intestinal Barrier Impairment
Klebsiella oxytoca causes antibiotic-associated hemorrhagic colitis and diarrhea. This was attributed largely to its secreted cytotoxins tilivalline and tilimycin, inductors of epithelial apoptosis. To study whether Klebsiella oxytoca exerts further barrier effects, T84 monolayers were challenged with bacterial supernatants derived from tilivalline/tilimycin-producing AHC6 or its isogeneic tilivalline/tilimycin-deficient strain Mut-89. Both preparations decreased transepithelial resistance, enhanced fluorescein and FITC-dextran-4kDa permeabilities, and reduced expression of barrier-forming tight junction proteins claudin-5 and -8. Laser scanning microscopy indicated redistribution of both claudins off the tight junction region in T84 monolayers as well as in colon crypts of mice infected with AHC6 or Mut-89, indicating that these effects are tilivalline/tilimycin-independent. Furthermore, claudin-1 was affected, but only in a tilivalline/tilimycin-dependent manner. In conclusion, Klebsiella oxytoca induced intestinal barrier impairment by two mechanisms: the tilivalline/tilimycin-dependent one, acting by increasing cellular apoptosis and a tilivalline/tilimycin-independent one, acting by weakening the paracellular pathway through the tight junction proteins claudin-5 and -8
Two-point density correlations of quasicondensates in free expansion
We measure the two-point density correlation function of freely expanding
quasicondensates in the weakly interacting quasi-one-dimensional (1D) regime.
While initially suppressed in the trap, density fluctuations emerge gradually
during expansion as a result of initial phase fluctuations present in the
trapped quasicondensate. Asymptotically, they are governed by the thermal
coherence length of the system. Our measurements take place in an intermediate
regime where density correlations are related to near-field diffraction effects
and anomalous correlations play an important role. Comparison with a recent
theoretical approach described by Imambekov et al. yields good agreement with
our experimental results and shows that density correlations can be used for
thermometry of quasicondensates.Comment: 4 pages, 4 figures, minor change
Application of carbon4humic preparations for detoxification of industrial waste and industrial waters from uranium and mercury
Анализ влияния технологических параметров на процессы промысловой подготовки нефти
Результаты испытаний различных деэмульгаторов при подготовке нефти.Объектом исследования: технология подготовки нефти Вынгапуровского месторождения, влияние деэмульгаторов на качество подготовки нефти.
Цель работы Определение возможности применения деэмульгаторов марки UnidemES при подготовке нефти на ДНС-2 с УПСВ Вынгапуровского месторождения ОАО «Газпромнефть-Ноябрьскнефтегаз».Object of research: technology of preparation of oil of the Vyngapurovsky field, influence of deemulgator on oil quality of training.
The work purpose Definition of a possibility of application of deemulgator of the UnidemES brand by preparation of oil on DNS-2 with UPSV of the Vyngapurovsky field of joint stock company "Gazpromneft-Noyabrskneftega
Two-point phase correlations of a one-dimensional bosonic Josephson junction
We realize a one-dimensional Josephson junction using quantum degenerate Bose
gases in a tunable double well potential on an atom chip. Matter wave
interferometry gives direct access to the relative phase field, which reflects
the interplay of thermally driven fluctuations and phase locking due to
tunneling. The thermal equilibrium state is characterized by probing the full
statistical distribution function of the two-point phase correlation.
Comparison to a stochastic model allows to measure the coupling strength and
temperature and hence a full characterization of the system
Single-particle-sensitive imaging of freely propagating ultracold atoms
We present a novel imaging system for ultracold quantum gases in expansion.
After release from a confining potential, atoms fall through a sheet of
resonant excitation laser light and the emitted fluorescence photons are imaged
onto an amplified CCD camera using a high numerical aperture optical system.
The imaging system reaches an extraordinary dynamic range, not attainable with
conventional absorption imaging. We demonstrate single-atom detection for
dilute atomic clouds with high efficiency where at the same time dense
Bose-Einstein condensates can be imaged without saturation or distortion. The
spatial resolution can reach the sampling limit as given by the 8 \mu m pixel
size in object space. Pulsed operation of the detector allows for slice images,
a first step toward a 3D tomography of the measured object. The scheme can
easily be implemented for any atomic species and all optical components are
situated outside the vacuum system. As a first application we perform
thermometry on rubidium Bose-Einstein condensates created on an atom chip.Comment: 24 pages, 10 figures. v2: as publishe
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