406 research outputs found
Generalized Fractal Kinetics in Complex Systems (Application to Biophysics and Biothechnology)
We derive a universal function for the kinetics of complex systems. This
kinetic function unifies and generalizes previous theoretical attempts to
describe what has been called "fractal kinetic".The concentration evolutionary
equation is formally similar to the relaxation function obtained in the
stochastic theory of relaxation, with two exponents a and n. The first one is
due to memory effects and short-range correlations and the second one finds its
origin in the long-range correlations and geometrical frustrations which give
rise to ageing behavior. These effects can be formally handled by introducing
adequate probability distributions for the rate coefficient. We show that the
distribution of rate coefficients is the consequence of local variations of the
free energy (energy landscape) appearing in the exponent of the Arrhenius
formula. We discuss briefly the relation of the (n,a) kinetic formalism with
the Tsallis theory of nonextensive systems.Comment: 15 pages, 3 figures, submitted to Physica
Structure of Extremely Nanosized and Confined In-O Species in Ordered Porous Materials
Perturbed-angular correlation, x-ray absorption, and small-angle x-ray
scattering spectroscopies were suitably combined to elucidate the local
structure of highly diluted and dispersed InOx species confined in porous of
ZSM5 zeolite. These novel approach allow us to determined the structure of
extremely nanosized In-O species exchanged inside the 10-atom-ring channel of
the zeolite, and to quantify the amount of In2O3 crystallites deposited onto
the external zeolite surface.Comment: 4 pages, 5 postscript figures, REVTEX4, published in Physical Review
Letter
p-Adic description of characteristic relaxation in complex systems
This work is a further development of an approach to the description of
relaxation processes in complex systems on the basis of the p-adic analysis. We
show that three types of relaxation fitted into the Kohlrausch-Williams-Watts
law, the power decay law, or the logarithmic decay law, are similar random
processes. Inherently, these processes are ultrametric and are described by the
p-adic master equation. The physical meaning of this equation is explained in
terms of a random walk constrained by a hierarchical energy landscape. We also
discuss relations between the relaxation kinetics and the energy landscapes.Comment: AMS-LaTeX (+iopart style), 9 pages, submitted to J.Phys.
Universal behavior of localization of residue fluctuations in globular proteins
Localization properties of residue fluctuations in globular proteins are
studied theoretically by using the Gaussian network model. Participation ratio
for each residue fluctuation mode is calculated. It is found that the
relationship between participation ratio and frequency is similar for all
globular proteins, indicating a universal behavior in spite of their different
size, shape, and architecture.Comment: 4 pages, 3 figures. To appear in Phys. Rev.
Protein sequence and structure: Is one more fundamental than the other?
We argue that protein native state structures reside in a novel "phase" of
matter which confers on proteins their many amazing characteristics. This phase
arises from the common features of all globular proteins and is characterized
by a sequence-independent free energy landscape with relatively few low energy
minima with funnel-like character. The choice of a sequence that fits well into
one of these predetermined structures facilitates rapid and cooperative
folding. Our model calculations show that this novel phase facilitates the
formation of an efficient route for sequence design starting from random
peptides.Comment: 7 pages, 4 figures, to appear in J. Stat. Phy
Efficient Analysis of High Dimensional Data in Tensor Formats
In this article we introduce new methods for the analysis of high dimensional data in tensor formats, where the underling data come from the stochastic elliptic boundary value problem. After discretisation of the deterministic operator as well as the presented random fields via KLE and PCE, the obtained high dimensional operator can be approximated via sums of elementary tensors. This tensors representation can be effectively used for computing different values of interest, such as maximum norm, level sets and cumulative distribution function. The basic concept of the data analysis in high dimensions is discussed on tensors represented in the canonical format, however the approach can be easily used in other tensor formats. As an intermediate step we describe efficient iterative algorithms for computing the characteristic and sign functions as well as pointwise inverse in the canonical tensor format. Since during majority of algebraic operations as well as during iteration steps the representation rank grows up, we use lower-rank approximation and inexact recursive iteration schemes
Recoilless Resonant Absorption of Monochromatic Neutrino Beam for Measuring Delta m^2_{31} and theta_{13}
We discuss, in the context of precision measurement of Delta m^2_{31} and
theta_{13}, physics capabilities enabled by the recoilless resonant absorption
of monochromatic antineutrino beam enhanced by the M\"ossbauer effect recently
proposed by Raghavan. Under the assumption of small relative systematic error
of a few tenth of percent level between measurement at different detector
locations, we give analytical and numerical estimates of the sensitivities to
Delta m^2_{31} and sin^2 2theta_{13}. The accuracies of determination of them
are enormous; The fractional uncertainty in Delta m^2_{31} achievable by 10
point measurement is 0.6% (2.4%) for sin^2 2theta_{13} = 0.05, and the
uncertainty of sin^2 2theta_{13} is 0.002 (0.008) both at 1 sigma CL with the
optimistic (pessimistic) assumption of systematic error of 0.2% (1%). The
former opens a new possibility of determining the neutrino mass hierarchy by
comparing the measured value of Delta m^2_{31} with the one by accelerator
experiments, while the latter will help resolving the theta_{23} octant
degeneracy.Comment: 23 pages, 3 figures, version to appear in New Journal of Physic
Quantum dynamics in strong fluctuating fields
A large number of multifaceted quantum transport processes in molecular
systems and physical nanosystems can be treated in terms of quantum relaxation
processes which couple to one or several fluctuating environments. A thermal
equilibrium environment can conveniently be modelled by a thermal bath of
harmonic oscillators. An archetype situation provides a two-state dissipative
quantum dynamics, commonly known under the label of a spin-boson dynamics. An
interesting and nontrivial physical situation emerges, however, when the
quantum dynamics evolves far away from thermal equilibrium. This occurs, for
example, when a charge transferring medium possesses nonequilibrium degrees of
freedom, or when a strong time-dependent control field is applied externally.
Accordingly, certain parameters of underlying quantum subsystem acquire
stochastic character. Herein, we review the general theoretical framework which
is based on the method of projector operators, yielding the quantum master
equations for systems that are exposed to strong external fields. This allows
one to investigate on a common basis the influence of nonequilibrium
fluctuations and periodic electrical fields on quantum transport processes.
Most importantly, such strong fluctuating fields induce a whole variety of
nonlinear and nonequilibrium phenomena. A characteristic feature of such
dynamics is the absence of thermal (quantum) detailed balance.Comment: review article, Advances in Physics (2005), in pres
Homological Mirror Symmetry for Calabi-Yau hypersurfaces in projective space
We prove Homological Mirror Symmetry for a smooth d-dimensional Calabi-Yau
hypersurface in projective space, for any d > 2 (for example, d = 3 is the
quintic three-fold). The main techniques involved in the proof are: the
construction of an immersed Lagrangian sphere in the `d-dimensional pair of
pants'; the introduction of the `relative Fukaya category', and an
understanding of its grading structure; a description of the behaviour of this
category with respect to branched covers (via an `orbifold' Fukaya category); a
Morse-Bott model for the relative Fukaya category that allows one to make
explicit computations; and the introduction of certain graded categories of
matrix factorizations mirror to the relative Fukaya category.Comment: 133 pages, 17 figures. Changes to the argument ruling out sphere
bubbling in the relative Fukaya category, and dealing with the behaviour of
the symplectic form under branched covers. Other minor changes suggested by
the referee. List of notation include
Neuer Kopf, alte Ideen? : "Normalisierung" des Front National unter Marine Le Pen
In this article, it is investigated
whether vibrational entropy
(VE) is an important contribution to the free energy of globular proteins
at ambient conditions. VE represents the major configurational-entropy
contribution of these proteins. By definition, it is an average of
the configurational entropies of the protein within single minima
of the energy landscape, weighted by their occupation probabilities.
Its large part originates from thermal motion of flexible torsion
angles giving rise to the finite peak widths observed in torsion angle
distributions. While VE may affect the equilibrium properties of proteins,
it is usually neglected in numerical calculations as its consideration
is difficult. Moreover, it is sometimes believed that all well-packed
conformations of a globular protein have similar VE anyway. Here, we measure explicitly the VE for six different conformations from simulation data of a test protein. Estimates
are obtained using the quasi-harmonic approximation for three coordinate
sets, Cartesian, bond-angle-torsion (BAT), and a new set termed rotamer-degeneracy
lifted BAT coordinates by us. The new set gives improved estimates
as it overcomes a known shortcoming of the quasi-harmonic approximation
caused by multiply populated rotamer states, and it may serve for
VE estimation of macromolecules in a very general context. The obtained
VE values depend considerably on the type of coordinates used. However,
for all coordinate sets we find large entropy differences between
the conformations, of the order of the overall stability of the protein.
This result may have important implications on the choice of free
energy expressions used in software for protein structure prediction,
protein design, and NMR refinement
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