306 research outputs found
Structure Determination of Oligosaccharides Isolated from A + , H + and A â H â Hog-Submaxillary-Gland Mucin Glyoproteins, by 360-MHz 1 H-NMR Spectroscopy, Permethylation Analysis and Mass Spectrometry
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65915/1/j.1432-1033.1981.tb05545.x.pd
A quantum mechanical description of the experiment on the observation of gravitationally bound states
Quantum states in the Earth's gravitational field were observed, when
ultra-cold neutrons fall under gravity. The experimental results can be
described by the quantum mechanical scattering model as it is presented here.
We also discuss other geometries of the experimental setup which correspond to
the absence or the reversion of gravity. Since our quantum mechanical model
describes, particularly, the experimentally realized situation of reversed
gravity quantitatively, we can practically rule out alternative explanations of
the quantum states in terms of pure confinement effects.Comment: LaTeX, 10 pages, 4 figures, v2: references adde
Quantum Revivals in Periodically Driven Systems close to nonlinear resonance
We calculate the quantum revival time for a wave-packet initially well
localized in a one-dimensional potential in the presence of an external
periodic modulating field. The dependence of the revival time on various
parameters of the driven system is shown analytically. As an example of
application of our approach, we compare the analytically obtained values of the
revival time for various modulation strengths with the numerically computed
ones in the case of a driven gravitational cavity. We show that they are in
very good agreement.Comment: 14 pages, 1 figur
Coherent Evolution of Bouncing Bose-Einstein Condensates
We investigate the evolution of Bose-Einstein condensates falling under
gravity and bouncing off a mirror formed by a far-detuned sheet of light. After
reflection, the atomic density profile develops splitting and interference
structures which depend on the drop height, on the strength of the light sheet,
as well as on the initial mean field energy and size of the condensate. We
compare experimental results with simulations of the Gross-Pitaevski equation.
A comparison with the behaviour of bouncing thermal clouds allows to identify
quantum features specific for condensates.Comment: 4 page
Optics with an Atom Laser Beam
We report on the atom optical manipulation of an atom laser beam. Reflection,
focusing and its storage in a resonator are demonstrated. Precise and versatile
mechanical control over an atom laser beam propagating in an inhomogeneous
magnetic field is achieved by optically inducing spin-flips between atomic
ground states with different magnetic moment. The magnetic force acting on the
atoms can thereby be effectively switched on and off. The surface of the atom
optical element is determined by the resonance condition for the spin-flip in
the inhomogeneous magnetic field. A mirror reflectivity of more than 98% is
measured
Quantum damping of position due to energy measurements
Quantum theory for measurements of energy is introduced and its consequences
for the average position of monitored dynamical systems are analyzed. It turns
out that energy measurements lead to a localization of the expectation values
of other observables. This is manifested, in the case of position, as a damping
of the motion without classical analogue. Quantum damping of position for an
atom bouncing on a reflecting surface in presence of a homogeneous
gravitational field is dealt in detail and the connection with an experiment
already performed in the classical regime is studied. We show that quantum
damping is testable provided that the same measurement strength obtained in the
experimental verification of the quantum Zeno effect in atomic spectroscopy [W.
M. Itano et al., Phys. Rev. A {\bf 41}, 2295 (1990)] is made available.Comment: 19 pages + 4 figures available upon request; Plain REVTeX; To be
published in Phys. Rev.
Creating a low-dimensional quantum gas using dark states in an inelastic evanescent-wave mirror
We discuss an experimental scheme to create a low-dimensional gas of
ultracold atoms, based on inelastic bouncing on an evanescent-wave mirror.
Close to the turning point of the mirror, the atoms are transferred into an
optical dipole trap. This scheme can compress the phase-space density and can
ultimately yield an optically-driven atom laser. An important issue is the
suppression of photon scattering due to ``cross-talk'' between the mirror
potential and the trapping potential. We propose that for alkali atoms the
photon scattering rate can be suppressed by several orders of magnitude if the
atoms are decoupled from the evanescent-wave light. We discuss how such dark
states can be achieved by making use of circularly-polarized evanescent waves.Comment: 8 pages, 4 figure
Lifetime and point prevalence of psychotic symptoms in adults with bipolar disorders: a systematic review and meta-analysis
Psychotic symptoms, that we defined as delusions or hallucinations, are common in bipolar
disorders (BD). This systematic review and meta-analysis aims to synthesise the literature on
both lifetime and point prevalence rates of psychotic symptoms across different BD subtypes,
including both BD type I (BDI) and BD type II (BDII). We performed a systematic search of
Medline, PsycINFO, Embase and Cochrane Library until 5 August 2021. Fifty-four studies
(N = 23 461) of adults with BD met the predefined inclusion criteria for evaluating lifetime
prevalence, and 24 studies (N = 6480) for evaluating point prevalence. Quality assessment
and assessment of publication bias were performed. Prevalence rates were calculated using
random effects meta-analysis, here expressed as percentages with a 95% confidence interval
(CI). In studies of at least moderate quality, the pooled lifetime prevalence of psychotic
symptoms in BDI was 63% (95% CI 57.5â68) and 22% (95% CI 14â33) in BDII. For BDI
inpatients, the pooled lifetime prevalence was 71% (95% CI 61â79). There were no studies
of community samples or inpatient BDII. The pooled point prevalence of psychotic symptoms
in BDI was 54% (95 CI 41â67). The point prevalence was 57% (95% CI 47â66) in manic
episodes and 13% (95% CI 7â23.5) in depressive episodes. There were not enough studies
in BDII, BDI depression, mixed episodes and outpatient BDI. The pooled prevalence of
psychotic symptoms in BDI may be higher than previously reported. More studies are needed
for depressive and mixed episodes and community samples.
Prospero registration number: CRD 42017052706
Substrate-based atom waveguide using guided two-color evanescent light fields
We propose a dipole-force linear waveguide which confines neutral atoms up to
lambda/2 above a microfabricated single-mode dielectric optical guide. The
optical guide carries far blue-detuned light in the horizontally-polarized TE
mode and far red-detuned light in the vertically-polarized TM mode, with both
modes close to optical cut-off. A trapping minimum in the transverse plane is
formed above the optical guide due to the differing evanescent decay lengths of
the two modes. This design allows manufacture of mechanically stable
atom-optical elements on a substrate. We calculate the full vector bound modes
for an arbitrary guide shape using two-dimensional non-uniform finite elements
in the frequency-domain, allowing us to optimize atom waveguide properties. We
find that a rectangular optical guide of 0.8um by 0.2um carrying 6mW of total
laser power (detuning +-15nm about the D2 line) gives a trap depth of 200uK for
cesium atoms (m_F = 0), transverse oscillation frequencies of f_x = 40kHz and
f_y = 160kHz, collection area ~ 1um^2 and coherence time of 9ms. We discuss the
effects of non-zero m_F, surface interactions, heating rate, the substrate
refractive index, and the limits on waveguide bending radius.Comment: 12 pages, 4 figures, revtex, submitted to Phys. Rev. A Replaced:
final version accepted by PRA v.61 Feb 2000. (2 paragraphs added
European consensus meeting of ARM-Net members concerning diagnosis and early management of newborns with anorectal malformations.
The ARM-Net (anorectal malformation network) consortium held a consensus meeting in which the classification of ARM and preoperative workup were evaluated with the aim of improving monitoring of treatment and outcome. The Krickenbeck classification of ARM and preoperative workup suggested by Levitt and Peña, used as a template, were discussed, and a collaborative consensus was achieved. The Krickenbeck classification is appropriate in describing ARM for clinical use. The preoperative workup was slightly modified. In males with a visible fistula, no cross-table lateral X-ray is needed and an anoplasty or (mini-) posterior sagittal anorectoplasty can directly be performed. In females with a small vestibular fistula (Hegar size 5 mm, and in the meantime, gentle painless dilatations can be performed. In both male and female perineal fistula and either a low birth weight (<2,000 g) or severe associated congenital anomalies, prolonged preoperative painless dilatations might be indicated to decrease perioperative morbidity caused by general anesthesia. The Krickenbeck classification is appropriate in describing ARM for clinical use. Some minor modifications to the preoperative workup by Levitt and Peña have been introduced in order to refine terminology and establish a comprehensive preoperative workup
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