5,344 research outputs found
From Micro to Macro: Examinations of Individual Level WorkâFamily Conflict and Organizational Level Entrepreneurial Orientation
Effect of Rotations and Shape Resonances on Photoassociation and Photoacceleration by Ultrashort Infrared Laser Pulses
A quantum dynamical description of an atomic collision pair interacting with the electric field of a short infrared laser pulse is developed. Inelastic processes in the electronic ground state are due to stimulated emission resulting in photoassociation, or absorption leading to photoacceleration. A perturbative approach based on a state space representation is compared with a numerical treatment using a grid representation in coordinate space. Special emphasis is on the role of rotations and, in particular, of shape resonances. It is shown that these quasibound states which are supported by the centrifugal barrier (for J> 0) can be used as initial states to effectively populate a selected bound state with specific vibrational and rotational quantum number (photoassociation), or a partial wave of a scattering state with defined energy and rotational quantum number (photoacceleration). Simulations are carried out for the prototype H + Cl collision pair. Also the effect of averaging over initial conditions (velocity, angular momenta) is investigated for a supersonic beam experiment. For a narrow velocity distribution, we predict the presence of a resonance structure of the association and acceleration probability as a function of the mean collision energy
Femtosecond Quantum Dynamics of Photoassociation Reactions: The Exciplex Formation of Mercury
A quantum dynamical wave packet description of photoassociation reactions induced by short laser pulses is developed including both vibrational/translation and rotational degrees of freedom. Various levels of approximation (perturbation approach, rotating wave approximation) are discussed. Simulations of the exciplex formation of mercury are performed and related to recent pump-probe experiments by Marvet and Dantus [Chem. Phys. Lett. 245 (1995) 393]. It is shown that in these experiments photoassociation is only due to bound â free transitions and does not proceed via bound â bound transitions from a van-der-Waals precursor. The calculated spectra show both vibrational and rotational coherence structure which can be interpreted in terms of quantum beats between different rovibrational states populated during the photoassociation process. The thermally averaged spectra show good qualitative agreement with the experimental data
Comment on Femtochemistry of Bimolecular Reactions from van der Waals Precursors versus Collision Pairs
Josephson effects in dilute Bose-Einstein condensates
We propose an experiment that would demonstrate the ``dc'' and ``ac''
Josephson effects in two weakly linked Bose-Einstein condensates. We consider a
time-dependent barrier, moving adiabatically across the trapping potential. The
phase dynamics are governed by a ``driven-pendulum'' equation, as in
current-driven superconducting Josephson junctions. At a critical velocity of
the barrier (proportional to the critical tunneling current), there is a sharp
transition between the ``dc'' and ``ac'' regimes. The signature is a sudden
jump of a large fraction of the relative condensate population. Analytical
predictions are compared with a full numerical solution of the time dependent
Gross-Pitaevskii equation, in an experimentally realistic situation.Comment: 4 pages, 1 figur
Integer quantum Hall effect of interacting electrons: dynamical scaling and critical conductivity
We report on a study of interaction effects on the polarization of a
disordered two-dimensional electron system in a strong magnetic field. Treating
the Coulomb interaction within the time-dependent Hartree-Fock approximation we
find numerical evidence for dynamical scaling with a dynamical critical
exponent z=1 at the integer quantum Hall plateau transition in the lowest
Landau level. Within the numerical accuracy of our data the conductivity at the
transition and the anomalous diffusion exponent are given by the values for
non-interacting electrons, independent of the strength of the interaction.Comment: Minor changes. Final version to be published in Phys. Rev. Lett. June
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Etiology, 3-Month Functional Outcome and Recurrent Events in Non-Traumatic Intracerebral Hemorrhage
BACKGROUND AND PURPOSE
Knowledge about different etiologies of non-traumatic intracerebral hemorrhage (ICH) and their outcomes is scarce.
METHODS
We assessed prevalence of pre-specified ICH etiologies and their association with outcomes in consecutive ICH patients enrolled in the prospective Swiss Stroke Registry (2014 to 2019).
RESULTS
We included 2,650 patients (mean±standard deviation age 72±14 years, 46.5% female, median National Institutes of Health Stroke Scale 8 [interquartile range, 3 to 15]). Etiology was as follows: hypertension, 1,238 (46.7%); unknown, 566 (21.4%); antithrombotic therapy, 227 (8.6%); cerebral amyloid angiopathy (CAA), 217 (8.2%); macrovascular cause, 128 (4.8%); other determined etiology, 274 patients (10.3%). At 3 months, 880 patients (33.2%) were functionally independent and 664 had died (25.1%). ICH due to hypertension had a higher odds of functional independence (adjusted odds ratio [aOR], 1.33; 95% confidence interval [CI], 1.00 to 1.77; P=0.05) and lower mortality (aOR, 0.64; 95% CI, 0.47 to 0.86; P=0.003). ICH due to antithrombotic therapy had higher mortality (aOR, 1.62; 95% CI, 1.01 to 2.61; P=0.045). Within 3 months, 4.2% of patients had cerebrovascular events. The rate of ischemic stroke was higher than that of recurrent ICH in all etiologies but CAA and unknown etiology. CAA had high odds of recurrent ICH (aOR, 3.38; 95% CI, 1.48 to 7.69; P=0.004) while the odds was lower in ICH due to hypertension (aOR, 0.42; 95% CI, 0.19 to 0.93; P=0.031).
CONCLUSIONS
Although hypertension is the leading etiology of ICH, other etiologies are frequent. One-third of ICH patients are functionally independent at 3 months. Except for patients with presumed CAA, the risk of ischemic stroke within 3 months of ICH was higher than the risk of recurrent hemorrhage
Characterization of irradiated RD53A pixel modules with passive CMOS sensors
We are investigating the feasibility of using CMOS foundries to fabricate
silicon detectors, both for pixels and for large-area strip sensors. The
availability of multi-layer routing will provide the freedom to optimize the
sensor geometry and the performance, with biasing structures in poly-silicon
layers and MIM-capacitors allowing for AC coupling. A prototyping production of
strip test-structures and RD53A compatible pixel sensors was recently completed
at LFoundry in a 150nm CMOS process. This paper will focus on the
characterization of irradiated and non-irradiated pixel modules, composed by a
CMOS passive sensor interconnected to a RD53A chip. The sensors are designed
with a pixel cell of in case of DC coupled
devices and for the AC coupled ones. Their
performance in terms of charge collection, position resolution, and hit
efficiency was studied with measurements performed in the laboratory and with
beam tests. The RD53A modules with LFoundry silicon sensors were irradiated to
fluences up to
Educational recommendations for the conduct, content and format of EULAR musculoskeletal ultrasound Teaching the Teachers Courses
To produce educational guidelines for the conduct, content and format of theoretical and practical teaching at EULAR musculoskeletal ultrasound (MSUS) Teaching the Teachers (TTT) Courses
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