2,625 research outputs found
Effects of low-level deuterium enrichment on bacterial growth
Using very precise (up to 0.05%) measurements of the growth parameters for
bacteria E. coli grown on minimal media, we aimed to determine the lowest
deuterium concentration at which the adverse effects that are prominent at
higher enrichments start to become noticeable. Such a threshold was found at
0.5% D, a surprisingly high value, while the ultralow deuterium concentrations
(up to 0.25% D) showed signs of the opposite trend. Bacterial adaptation for
400 generations in isotopically different environment confirmed preference for
ultralow (up to 0.25% D) enrichment. This effect appears to be similar to those
described in sporadic but multiple earlier reports. Possible explanations
include hormesis and isotopic resonance phenomena, with the latter explanation
being favored.Comment: Accepted to PLoS One. Press embargo applie
Dynamics of filaments of scroll waves
This has been written as a chapter for "Engineering Chemical Complexity II",
and as such does not have an abstract.Comment: 18 pages, 10 figure
A new universal law for the Liesegang pattern formation
Classical regularities describing the Liesegang phenomenon have been observed and extensively studied in laboratory experiments for a long time. These have been verified in the last two decades, both theoretically and using simulations. However, they are only applicable if the observed system is driven by reaction and diffusion. We suggest here a new universal law, which is also valid in the case of various transport dynamics (purely diffusive, purely advective, and diffusion-advection cases). We state that ptot~Xc, where ptot yields the total amount of the precipitate and Xc is the center of gravity. Besides the theoretical derivation experimental and numerical evidence for the universal law is provided. In contrast to the classical regularities, the introduced quantities are continuous functions of time
Electron-conformational transformations in nanoscopic RyR channels govern both the heart's contraction and beating
We show that a simple biophysically based electron-conformational model of
RyR channel is able to explain and describe on equal footing the oscillatory
regime of the heart's cell release unit both in sinoatrial node (pacemaker)
cells under normal physiological conditions and in ventricular myocytes under
Ca SR overload.Comment: 6 pages, 3 figure
Localization of response functions of spiral waves in the FitzHugh-Nagumo system
Dynamics of spiral waves in perturbed, e. g. slightly inhomogeneous or
subject to a small periodic external force, two-dimensional autowave media can
be described asymptotically in terms of Aristotelean dynamics, so that the
velocities of the spiral wave drift in space and time are proportional to the
forces caused by the perturbation. The forces are defined as a convolution of
the perturbation with the spiral's Response Functions, which are eigenfunctions
of the adjoint linearised problem. In this paper we find numerically the
Response Functions of a spiral wave solution in the classic excitable
FitzHugh-Nagumo model, and show that they are effectively localised in the
vicinity of the spiral core.Comment: 11 pages, 2 figure
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