143 research outputs found
Extended Kramers-Moyal analysis applied to optical trapping
The Kramers-Moyal analysis is a well established approach to analyze
stochastic time series from complex systems. If the sampling interval of a
measured time series is too low, systematic errors occur in the analysis
results. These errors are labeled as finite time effects in the literature. In
the present article, we present some new insights about these effects and
discuss the limitations of a previously published method to estimate
Kramers-Moyal coefficients at the presence of finite time effects. To increase
the reliability of this method and to avoid misinterpretations, we extend it by
the computation of error estimates for estimated parameters using a Monte Carlo
error propagation technique. Finally, the extended method is applied to a data
set of an optical trapping experiment yielding estimations of the forces acting
on a Brownian particle trapped by optical tweezers. We find an increased
Markov-Einstein time scale of the order of the relaxation time of the process
which can be traced back to memory effects caused by the interaction of the
particle and the fluid. Above the Markov-Einstein time scale, the process can
be very well described by the classical overdamped Markov model for Brownian
motion.Comment: 14 pages, 18 figure
Observation of Nonspreading Wave Packets in an Imaginary Potential
We propose and experimentally demonstrate a method to prepare a nonspreading
atomic wave packet. Our technique relies on a spatially modulated absorption
constantly chiseling away from an initially broad de Broglie wave. The
resulting contraction is balanced by dispersion due to Heisenberg's uncertainty
principle. This quantum evolution results in the formation of a nonspreading
wave packet of Gaussian form with a spatially quadratic phase. Experimentally,
we confirm these predictions by observing the evolution of the momentum
distribution. Moreover, by employing interferometric techniques, we measure the
predicted quadratic phase across the wave packet. Nonspreading wave packets of
this kind also exist in two space dimensions and we can control their amplitude
and phase using optical elements.Comment: 4 figure
Macromolecular theory of solvation and structure in mixtures of colloids and polymers
The structural and thermodynamic properties of mixtures of colloidal spheres
and non-adsorbing polymer chains are studied within a novel general
two-component macromolecular liquid state approach applicable for all size
asymmetry ratios. The dilute limits, when one of the components is at infinite
dilution but the other concentrated, are presented and compared to field theory
and models which replace polymer coils with spheres. Whereas the derived
analytical results compare well, qualitatively and quantitatively, with
mean-field scaling laws where available, important differences from ``effective
sphere'' approaches are found for large polymer sizes or semi-dilute
concentrations.Comment: 23 pages, 10 figure
Spinal Cord Ischemia after Endovascular Repair of the Descending Thoracic Aorta in a Sheep Model
In vivo evidence of htid suppressive activity on ErbB-2 in breast cancers over expressing the receptor
Staphylococcal scalded skin syndrome in a premature newborn caused by methicillin-resistant Staphylococcus aureus: case report
Vaccine-associated enhanced respiratory pathology in COVID-19 hamsters after T(H)2-biased immunization
Vaccine-associated enhanced respiratory disease (VAERD) is a severe complication for some respiratory infections. To investigate the potential for VAERD induction in coronavirus disease 2019 (COVID-19), we evaluate two vaccine leads utilizing a severe hamster infection model: a T helper type 1 (T(H)1)-biased measles vaccine-derived candidate and a T(H)2-biased alum-adjuvanted, non-stabilized spike protein. The measles virus (MeV)-derived vaccine protects the animals, but the protein lead induces VAERD, which can be alleviated by dexamethasone treatment. Bulk transcriptomic analysis reveals that our protein vaccine prepares enhanced host gene dysregulation in the lung, exclusively up-regulating mRNAs encoding the eosinophil attractant CCL-11, T(H)2-driving interleukin (IL)-19, or T(H)2 cytokines IL-4, IL-5, and IL-13. Single-cell RNA sequencing (scRNA-seq) identifies lung macrophages or lymphoid cells as sources, respectively. Our findings imply that VAERD is caused by the concerted action of hyperstimulated macrophages and T(H)2 cytokine-secreting lymphoid cells and potentially links VAERD to antibody-dependent enhancement (ADE). In summary, we identify the cytokine drivers and cellular contributors that mediate VAERD after T(H)2-biased vaccination
Markov Stationary Equilibria in Stochastic Supermodular Games with Imperfect Private and Public Information
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