159 research outputs found
Binary self-similar one-dimensional quasilattices: Mutual local-derivability classification and substitution rules
Self-similar binary one-dimensional (1D) quasilattices (QLs) are classified
into mutual local-derivability (MLD) classes. It is shown that the MLD
classification is closely related to the number-theoretical classification of
parameters which specify the self-similar binary 1D QLs. An algorithm to derive
an explicit substitution rule, which prescribes the transformation of a QL into
another QL in the same MLD class, is presented. An explicit inflation rule,
which prescribes the transformation of the self-similar 1D QL into itself, is
obtained as a composition of the explicit substitution rules. Symmetric
substitution rules and symmetric inflation rules are extensively discussed.Comment: 24 pages, 4 figures, submitted to PR
Minimizing energy below the glass thresholds
Focusing on the optimization version of the random K-satisfiability problem,
the MAX-K-SAT problem, we study the performance of the finite energy version of
the Survey Propagation (SP) algorithm. We show that a simple (linear time)
backtrack decimation strategy is sufficient to reach configurations well below
the lower bound for the dynamic threshold energy and very close to the analytic
prediction for the optimal ground states. A comparative numerical study on one
of the most efficient local search procedures is also given.Comment: 12 pages, submitted to Phys. Rev. E, accepted for publicatio
Trace and antitrace maps for aperiodic sequences, their extensions and applications
We study aperiodic systems based on substitution rules by means of a
transfer-matrix approach. In addition to the well-known trace map, we
investigate the so-called `antitrace' map, which is the corresponding map for
the difference of the off-diagonal elements of the 2x2 transfer matrix. The
antitrace maps are obtained for various binary, ternary and quaternary
aperiodic sequences, such as the Fibonacci, Thue-Morse, period-doubling,
Rudin-Shapiro sequences, and certain generalizations. For arbitrary
substitution rules, we show that not only trace maps, but also antitrace maps
exist. The dimension of the our antitrace map is r(r+1)/2, where r denotes the
number of basic letters in the aperiodic sequence. Analogous maps for specific
matrix elements of the transfer matrix can also be constructed, but the maps
for the off-diagonal elements and for the difference of the diagonal elements
coincide with the antitrace map. Thus, from the trace and antitrace map, we can
determine any physical quantity related to the global transfer matrix of the
system. As examples, we employ these dynamical maps to compute the transmission
coefficients for optical multilayers, harmonic chains, and electronic systems.Comment: 13 pages, REVTeX, now also includes applications to electronic
systems, some references adde
New Cases of Universality Theorem for Gravitational Theories
The "Universality Theorem" for gravity shows that f(R) theories (in their
metric-affine formulation) in vacuum are dynamically equivalent to vacuum
Einstein equations with suitable cosmological constants. This holds true for a
generic (i.e. except sporadic degenerate cases) analytic function f(R) and
standard gravity without cosmological constant is reproduced if f is the
identity function (i.e. f(R)=R). The theorem is here extended introducing in
dimension 4 a 1-parameter family of invariants R' inspired by the
Barbero-Immirzi formulation of GR (which in the Euclidean sector includes also
selfdual formulation). It will be proven that f(R') theories so defined are
dynamically equivalent to the corresponding metric-affine f(R) theory. In
particular for the function f(R)=R the standard equivalence between GR and
Holst Lagrangian is obtained.Comment: 10 pages, few typos correcte
On an asymptotic estimate of the -loop correction in perturbative QCD
A recently proposed method of estimating the asymptotic behaviour of QCD
perturbation theory coefficients is critically reviewed and shown to contain
numerous invalid mathematical operations and unsubstantiated assumptions. We
discuss in detail why this procedure, based solely on renormalization group
(RG) considerations and analyticity constraints, cannot lead to such estimates.
We stress the importance of correct renormalization scheme (RS) dependence of
any meaningful asymptotic estimate and argue that the unambiguous summation of
QCD perturbation expansions for physical quantities requires information from
outside of perturbation theory itself.Comment: PRA-HEP-92/17, Latex, 20 pages of text plus 5 figures contained in 5
separate PS files. Four of them (corresponding to Figs.1,2,3,5) are appended
at the end of this file, the (somewhat larger one) corresponding to Fig.4 can
be obtained from any of the mentioned E-mail addresses upon request. E-mail
connections: J. Chyla - [email protected]) or h1kchy@dhhdesy3 P. Kolar -
[email protected]
Natural and projectively equivariant quantizations by means of Cartan Connections
The existence of a natural and projectively equivariant quantization in the
sense of Lecomte [20] was proved recently by M. Bordemann [4], using the
framework of Thomas-Whitehead connections. We give a new proof of existence
using the notion of Cartan projective connections and we obtain an explicit
formula in terms of these connections. Our method yields the existence of a
projectively equivariant quantization if and only if an \sl(m+1,\R)-equivariant
quantization exists in the flat situation in the sense of [18], thus solving
one of the problems left open by M. Bordemann.Comment: 13 page
Morita base change in Hopf-cyclic (co)homology
In this paper, we establish the invariance of cyclic (co)homology of left
Hopf algebroids under the change of Morita equivalent base algebras. The
classical result on Morita invariance for cyclic homology of associative
algebras appears as a special example of this theory. In our main application
we consider the Morita equivalence between the algebra of complex-valued smooth
functions on the classical 2-torus and the coordinate algebra of the
noncommutative 2-torus with rational parameter. We then construct a Morita base
change left Hopf algebroid over this noncommutative 2-torus and show that its
cyclic (co)homology can be computed by means of the homology of the Lie
algebroid of vector fields on the classical 2-torus.Comment: Final version to appear in Lett. Math. Phy
Recent growth coherence in long-term oak (Quercus spp.) ring width chronologies in the Czech Republic
Oak ring width measurements compiled from 44 sampling sites throughout the territory of the Czech Republic are analysed for the 1655-2013 period. Measurements taken at all these sites are sorted into 10 sub-chronologies on the basis of 5 environmental factors: soil moisture (dry/wet), elevation (low/high), age (young/old), species (Quercus robur or Q. petraea), and geographical position (east/west). Several statistical tests are applied to investigate existing significant differences between chronologies during 1920-2013. Further, the sensitivities of individual sub-chronologies to precipitation are compared. Three tests indicate 5 pairs of very similar sub-chronologies. Moreover, the growth-response to May-July precipitation totals is very much the same in these sub-chronologies. This analysis demonstrates that, even in the absence of certainty about age structure, species composition and some environmental factors in the earlier parts of oak ring width chronologies, the internal homogeneity of the chronology remains essentially unaffected, and the lack of such information does not preclude their use in dendroclimatology
Science with a small two-band UV-photometry mission II: Observations of stars and stellar systems
We outline the impact of a small two-band UV-photometry satellite mission on
the field of stellar physics, magnetospheres of stars, binaries, stellar
clusters, interstellar matter, and exoplanets. On specific examples of
different types of stars and stellar systems, we discuss particular
requirements for such satellite missions in terms of specific mission
parameters such as bandpass, precision, cadence, and mission duration. We show
that such a mission may provide crucial data not only for hot stars that emit
most of their light in UV, but also for cool stars, where UV traces their
activity. This is important, for instance, for exoplanetary studies, because
the level of stellar activity influences habitability. While the main asset of
the two-band UV mission rests in time-domain astronomy, an example of open
clusters proves that such a mission would be important also for the study of
stellar populations. Properties of the interstellar dust are best explored when
combining optical and IR information with observations in UV. It is well known
that dust absorbs UV radiation efficiently. Consequently, we outline how such a
UV mission can be used to detect eclipses of sufficiently hot stars by various
dusty objects and study disks, rings, clouds, disintegrating exoplanets or
exoasteroids. Furthermore, UV radiation can be used to study the cooling of
neutron stars providing information about the extreme states of matter in the
interiors of neutron stars and used for mapping heated spots on their surfaces.Comment: Submitted to Space Science Review
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