443 research outputs found
On the zero mass limit of tagged particle diffusion in the 1-d Rayleigh-gas
We consider the M -> 0 limit for tagged particle diffusion in a 1-dimensional
Rayleigh-gas, studied originaly by Sinai and Soloveichik (1986), respectively
by Szasz and Toth (1986). In this limit we derive a new type of model for
tagged paricle diffusion, with Calogero-Moser-Sutherland (i.e. inverse
quadratic) interaction potential between the two central particles. Computer
simulations on this new model reproduce exactly the numerical value of the
limiting variance obtained by Boldrighini, Frigio and Tognetti (2002).Comment: Dedicated to Domokos Szasz on his 65th birthda
Limit theorems in the stadium billiard
We prove that the Birkhoff sums for ``almost every'' relevant observable in
the stadium billiard obey a non-standard limit law. More precisely, the usual
central limit theorem holds for an observable if and only if its integral along
a one-codimensional invariant set vanishes, otherwise a
normalization is needed. As one of the two key steps in the argument, we obtain
a limit theorem that holds in Young towers with exponential return time
statistics in general, an abstract result that seems to be applicable to many
other situations.Comment: 46 page
Efficient Antihydrogen Detection in Antimatter Physics by Deep Learning
Antihydrogen is at the forefront of antimatter research at the CERN
Antiproton Decelerator. Experiments aiming to test the fundamental CPT symmetry
and antigravity effects require the efficient detection of antihydrogen
annihilation events, which is performed using highly granular tracking
detectors installed around an antimatter trap. Improving the efficiency of the
antihydrogen annihilation detection plays a central role in the final
sensitivity of the experiments. We propose deep learning as a novel technique
to analyze antihydrogen annihilation data, and compare its performance with a
traditional track and vertex reconstruction method. We report that the deep
learning approach yields significant improvement, tripling event coverage while
simultaneously improving performance by over 5% in terms of Area Under Curve
(AUC)
Statistical properties for flows with unbounded roof function, including the Lorenz attractor
For geometric Lorenz attractors (including the classical Lorenz attractor) we
obtain a greatly simplified proof of the central limit theorem which applies
also to the more general class of codimension two singular hyperbolic
attractors. We also obtain the functional central limit theorem and moment
estimates, as well as iterated versions of these results. A consequence is
deterministic homogenisation (convergence to a stochastic differential
equation) for fast-slow dynamical systems whenever the fast dynamics is
singularly hyperbolic of codimension two.Comment: Minor corrections. Published online in J. Stat. Phy
A practical review on the measurement tools for cellular adhesion force
Cell cell and cell matrix adhesions are fundamental in all multicellular
organisms. They play a key role in cellular growth, differentiation, pattern
formation and migration. Cell-cell adhesion is substantial in the immune
response, pathogen host interactions, and tumor development. The success of
tissue engineering and stem cell implantations strongly depends on the fine
control of live cell adhesion on the surface of natural or biomimetic
scaffolds. Therefore, the quantitative and precise measurement of the adhesion
strength of living cells is critical, not only in basic research but in modern
technologies, too. Several techniques have been developed or are under
development to quantify cell adhesion. All of them have their pros and cons,
which has to be carefully considered before the experiments and interpretation
of the recorded data. Current review provides a guide to choose the appropriate
technique to answer a specific biological question or to complete a biomedical
test by measuring cell adhesion
Building Protein Domain Based Composite Biobricks for Mammalian Expression Systems
The purpose of this RFC is to describe a method that allows the design of protein domain based parts, starting with gene centered information and translate these informations into BBF RFC 25 compatible part. The method is designed to be used in mammalian expression systems
Colour changes upon cooling of Lepidoptera scales containing photonic nanoarchitectures
The effects produced by the condensation of water vapours from the ambient in
the various intricate nanoarchitectures occurring in the wing scales of several
Lepidoptera species were investigated by controlled cooling (from room
temperature to -5 - -10 {\deg}C) combined with in situ measurement of changes
in the reflectance spectra. It was determined that, due to this procedure, all
photonic nanoarchitectures giving a reflectance maximum in the visible range
and having an open nanostructure exhibited alteration of the position of the
reflectance maximum associated with the photonic nanoarchitectures. The
photonic nanoarchitectures with a closed structure exhibited little to no
alteration in colour. Similarly, control specimens coloured by pigments did not
exhibit a colour change under the same conditions. Hence, this effect can be
used to identify species with open photonic nanoarchitectures in their scales.
For certain species, an almost complete disappearance of the reflectance
maximum was found. All specimens recovered their original colours following
warming and drying. Cooling experiments using thin copper wires demonstrated
that colour alterations could be limited to a millimetre, or below. Dried
museum specimens do not exhibit colour changes when cooled in the absence of a
heat sink due to the low heat capacity of the wings.Comment: 18 pages, 9 figures, including supplemen
Flow Routing with Unknown Rating Curves Using a State-Space Reservoir-Cascade-Type Formulation
Room temperature manipulation of long lifetime spins in metallic-like carbon nanospheres
The time-window for processing electron spin information (spintronics) in
solid-state quantum electronic devices is determined by the spinâlattice and
spinâspin relaxation times of electrons. Minimizing the effects of spinâorbit
coupling and the local magnetic contributions of neighbouring atoms on
spinâlattice and spinâspin relaxation times at room temperature remain
substantial challenges to practical spintronics. Here we report conduction
electron spinâlattice and spinâspin relaxation times of 175âns at 300âK in
37±7ânm carbon spheres, which is remarkably long for any conducting solid-
state material of comparable size. Following the observation of spin
polarization by electron spin resonance, we control the quantum state of the
electron spin by applying short bursts of an oscillating magnetic field and
observe coherent oscillations of the spin state. These results demonstrate the
feasibility of operating electron spins in conducting carbon nanospheres as
quantum bits at room temperature
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