pinecone/core-2020-05-10-deduplication huggingface dataset:
Collective Magnetic Excitations in SrCu_2(BO_3)_2

We study low temperature Raman data on phononic and magnetic excitations in
SrCu_2(BO_3)_2. Regarding the former, in the 0 to 350 cm-1 range we find
several pairs of quasi-degenerate modes which have different symmetries. Group
theoretical analysis suggests that the existence of these modes is related to
quite different atomic vibrational pattern, i.e. in-plane and c-axis.
Collective magnetic excitations are studied in terms of symmetry, resonance and
coupling mechanisms in zero and applied magnetic fields. The analysis of a
4-spin cluster allows us to understand the group symmetries of the zero field
Brillouin zone center spin gap branches around 24 cm-1 confirming the picture
of local elementary one-triplet modes. By considering an additional intra-dimer
DM interaction we are also able to understand the observed selection rules and
intensity variations of the spin gap branches in external magnetic fields
applied parallel or perpendicular to the dimer planes. We identified two
effective magnetic light scattering Hamiltonians responsible for the coupling
to the magnetic modes which allowed us to explain their resonance behavior.Comment: 16 pages, 14 figure
Magnetic and Charge Correlations in La{2-x-y}Nd_ySr_xCuO_4: Raman
  Scattering Study

Two aspects in connection with the magnetic properties of
La_{2-x-y}Nd_ySr_xCuO_4 single crystals are discussed. The first is related to
long wavelength magnetic excitations in x = 0, 0.01, and 0.03 La_{2-x}Sr_xCuO_4
detwinned crystals as a function of doping, temperature and magnetic field. Two
magnetic modes were observed within the AF region of the phase diagram. The one
at lower energies was identified with the spin-wave gap induced by the
antisymmetric DM interaction and its anisotropic properties in magnetic field
could be well explained using a canonical form of the spin Hamiltonian. A new
finding was a magnetic field induced mode whose dynamics allowed us to discover
a spin ordered state outside the AF order which was shown to persist in a 9 T
field as high as 100 K above the N\'eel temperature T_N for x = 0.01. For these
single magnon excitations we map out the Raman selection rules in magnetic
fields and demonstrate that their temperature dependent spectral weight is
peaked at the N\'eel temperature. The second aspect is related to phononic and
magnetic Raman scattering in La_{2-x-y}Nd_ySr_xCuO_4 with three doping
concentrations: x = 1/8, y = 0; x = 1/8, y = 0.4; and x = 0.01, y = 0. We
observed that around 1/8 Sr doping and independent of Nd concentration there
exists substantial disorder in the tilt pattern of the CuO_6 octahedra in both
the orthorhombic and tetragonal phases which persist down to 10 K and are
coupled to bond disorder in the cation layers. The weak magnitude of existing
charge/spin modulations in the Nd doped structure did not allow us to detect
specific Raman signatures on lattice dynamics or two-magnon scattering around
2200 cm-1.Comment: 26 pages, 22 figure
Gutzwiller-Correlated Wave Functions: Application to Ferromagnetic
  Nickel

Ferromagnetic Nickel is the most celebrated iron group metal with pronounced
discrepancies between the experimental electronic properties and predictions of
density functional theories. In this work, we show in detail that the recently
developed multi-band Gutzwiller theory provides a very good description of the
quasi-particle band structure of nickel. We obtain the correct exchange
splittings and we reproduce the experimental Fermi-surface topology. The
correct (111)-direction of the magnetic easy axis and the right order of
magnitude of the magnetic anisotropy are found. Our theory also reproduces the
experimentally observed change of the Fermi-surface topology when the magnetic
moment is oriented along the (001)-axis. In addition to the numerical study, we
give an analytical derivation for a much larger class of variational
wave-functions than in previous investigations. In particular, we cover cases
of superconductivity in multi-band lattice systems.Comment: 35 pages, 3 figure
Superconductivity of Magnesium Diboride: Theoretical Aspects

In this work we review our present understanding of superconductivity in
Magnesium Diboride from the theoretical perspective as it evolves from band
structure calculations. Particular emphasis is placed on two gap
superconductivity. Some of its peculiar consequences are discussed, in
particular upper critical field anisotropy and microwave conductivity.Comment: 27 pages, 13 figures, review article to be published in: A. V.
  Narlikar (Ed.), Frontiers in Superconducting Materials, Springer, Berlin,
  200
Superconductivity in heavy fermion compounds

We review the current state of experimental and theoretical investigations of
heavy fermion superconductors. We discuss most of the Ce-based compounds like
Ce122, Ce115, Ce218 and Ce131 classes and U-based superconductors like UBe_13
and UPd_2Al_3. In the former the emphasis is on the connection to quantum
critical phenomena and non-Fermi liquid behaviour. Recent neutron scattering
and hydrostatic pressure results on SDW/SC competition in the Ce122 system are
included. For the U-compounds we discuss the significance of dual models with
both localised and itinerant 5f electrons for mass enhancement and
superconducting pair formation. Itinerant spin fluctuation theories for
unconventional superconductivity are also reviewed.Comment: 74 pages, 29 figures. For a version of the manuscript including
  higher-resolution figures, see http://www.cpfs.mpg.de/~thalm/SCMaterials.pd
Statistical properties of absolute log-returns and a stochastic model of
  stock markets with heterogeneous agents

This paper is intended as an investigation of the statistical properties of
{\it absolute log-returns}, defined as the absolute value of the logarithmic
price change, for the Nikkei 225 index in the 28-year period from January 4,
1975 to December 30, 2002. We divided the time series of the Nikkei 225 index
into two periods, an inflationary period and a deflationary period. We have
previously [18] found that the distribution of absolute log-returns can be
approximated by the power-law distribution in the inflationary period, while
the distribution of absolute log-returns is well described by the exponential
distribution in the deflationary period.\par To further explore these empirical
findings, we have introduced a model of stock markets which was proposed in
[19,20]. In this model, the stock market is composed of two groups of traders:
{\it the fundamentalists}, who believe that the asset price will return to the
fundamental price, and {\it the interacting traders}, who can be noise traders.
We show through numerical simulation of the model that when the number of
interacting traders is greater than the number of fundamentalists, the
power-law distribution of absolute log-returns is generated by the interacting
traders' herd behavior, and, inversely, when the number of fundamentalists is
greater than the number of interacting traders, the exponential distribution of
absolute log-returns is generated.Comment: 12 pages, 5 figure
The Raman response of double wall carbon nanotubes

Raman spectroscopy on carbon nanotubes (CNT) yields a rich variety of
information owing to the close interplay between electronic and vibrational
properties. In this paper, we review the properties of double wall carbon
nanotubes (DWCNTs). In particular, it is shown that SWCNT encapsulating
C$_{60}$, so-called peapods, are transformed into DWCNTs when subject to a high
temperature treatment. The inner tubes are grown in a catalyst free environment
and do not suffer from impurities or defects that are usually encountered for
as-grown SWCNTs or DWCNTs. As a consequence, the inner tubes are grown with a
high degree of perfection as deduced from the unusually narrow radial breathing
mode (RBM) lines. This apostrophizes the interior of the SWCNTs as a nano-clean
room. The mechanism of the inner nanotube production from C$_{60}$ is
discussed. We also report recent studies aimed at the simplification and
industrial scaling up of the DWCNT production process utilizing a low
temperature peapod synthesis method. A splitting of the RBMs of inner tubes is
observed. This is related to the interaction between the two shells of the
DWCNTs as the same inner tube type can be encapsulated in different outer ones.
The sharp appearance of the inner tube RBMs allows a reliable assignment of the
tube modes to (n,m) indexes and thus provides a precise determination of the
relation between the tube diameter and the RBM frequencies.Comment: A review, 15 pages, 15 figure
Specification of requirements models

The main aim of this chapter is to present and discuss a set of modeling and specification techniques, in what concerns their ontology and support in the requirements representation of computer-based systems. A systematic classification
of meta-models, also called models of computation, is presented. This topic is highly relevant since it supports the definition of sound specification methodologies in relation to the semantic definition of the modeling views to adopt for a given system. The usage and applicability of Unified Modeling Language (UML) diagrams is also related to their corresponding meta-models. A set of desirable
characteristics for the specification methodologies is presented and justified to allow system designers and requirements engineers to more consciously define or choose a particular specification methodology. A heuristic-based approach to support
the transformation of user into system requirements is suggested, with some graphical examples in UML notation
Automatic Propagation of Uncertainties

???The original publication is available at www.springerlink.com???. Copyright Springer.Motivated by problems in metrology, we consider a numerical evaluation program y = f(x) as a model for a measurement process. We use a probability density function to represent the uncertainties in the inputs x and examine some of the consequences of using Automatic Differentiation to propagate these uncertainties to the outputs y.We show how to use a combination of Taylor series propagation and interval partitioning to obtain coverage (confidence) intervals and ellipsoids based on unbiased estimators for means and covariances of the outputs, even where f is sharply non-linear, and even when the level of probability required makes the use of Monte Carlo techniques computationally problematic
Market dynamics and agents behaviors: a computational approach

We explore market dynamics generated by the Santa-Fe Artificial Stock Market
model. It allows to study how agents adapt themselves to a market dynamic without knowing
its generation process. It was shown by Arthur and LeBaron, with the help of computer experiments, that agents in bounded rationality can make a rational global behavior emerge in this context. In the original model, agents do not ground their decision on an economic logic. Hence, we modify indicators used by agents to watch the market to give them more economic rationality. This leads us to divide agents in two groups: fundamentalists agents, who watch the market with classic economic indicators and speculator agents, who watch the market with technical indicators. This split allows us to study the influence of individual agents behaviors on global price dynamics. In this article, we show with the help of computational simulations that these two types of agents can generate classical market dynamics as well as perturbed ones (bubbles and kraches).
Comparative numerical study of Anderson localization in disordered
  electron systems

Taking into account that a proper description of disordered systems should
focus on distribution functions, the authors develop a powerful numerical
scheme for the determination of the probability distribution of the local
density of states (LDOS), which is based on a Chebyshev expansion with kernel
polynomial refinement and allows the study of large finite clusters (up to
$100^3$). For the three-dimensional Anderson model it is demonstrated that the
distribution of the LDOS shows a significant change at the disorder induced
delocalisation-localisation transition. Consequently, the so-called typical
density of states, defined as the geometric mean of the LDOS, emerges as a
natural order parameter. The calculation of the phase diagram of the Anderson
model proves the efficiency and reliability of the proposed approach in
comparison to other localisation criteria, which rely, e.g., on the decay of
the wavefunction or the inverse participation number.Comment: 13 pages, 10 figure
Evolution of Reciprocal Cooperation in the Avatamsaka Game

The Avatamsaka game is investigated both analytically and using computer simulations. The Avatamsaka game is a dependent game in which each agent’s payoff depends completely not on her own decision but on the other players’. Consequently, any combination of mixed strategies is a Nash equilibrium.Analysis and evolutionary simulations show that the socially optimal state becomes evolutionarily stable by a Pavlovian strategy in the repeated Avatamsaka game, and also in any kind of dependent game. The mechanism of the evolutionary process is investigated from the viewpoint of the agent’s memory and mutation of strategies.Book Series：Lecture Notes in Economics and Mathematical SystemsThis Book：The Complex Networks of Economic InteractionsEssays in Agent-Based Economics and Econophysic
A Direct Localization Method Using only the\ud
Bearings Extracted from Two Panoramic\ud
Views Along a Linear Trajectory

To operate successfully in any environment, mobile robots must be\ud
able to localize themselves accurately. In this paper, we describe a direct method\ud
(in the sense it does not use an iterative search) based on vision for localizing a\ud
mobile robot in an environment with only two observations along a linear trajectory.\ud
We only assume that the robot can visually identify landmarks and measure their\ud
bearings. Contrary to other existing approaches to landmark based navigation, we\ud
do not require any other sensors (like range sensors or wheel encoders) or the prior\ud
knowledge of relative distances between the landmarks. Given its low cost, the range\ud
of potential applications of our localization system is very wide. In particular, this\ud
system is ideally suited for domestic robots such as autonomous lawn-mowers and\ud
vacuum cleaners
Locomotion of a modular worm-like robot using a FPGA-based embedded microBlaze soft-processor

The final publication is available at Springer via http://dx.doi.org/10.1007/3-540-29461-9_85Modular reconfigurable robots offer the promise of more versatility, robustness, and low cost. They are composed of simple and small modules, capable of attach and detach one to each other. In this paper, a modular worm-like robot composed of a chain of 8 similar modules is presented. A travelling wave, that moves from the tail to the head, propels the robot forward. The positions of the articulations are calculated using the following parameters: waveform, amplitude, and wavelength. Instead of a conventional architecture, a FPGA-based soft-processor core is utilized. It includes a set of custom peripheral cores, written in VHDL. FPGAs make modular robots more versatile, adding some new featureas to the design of robots like reconfigurable control, hardware reuse, lower cost, fault-recovering, and software/hardware co-design.This research is supported by Project Number 07T/0052/2003-3 of the Consejería de
Educación de la Comunidad Autónoma de Madrid, Spain
Construction of Good Rank-1 Lattice Rules Based on the Weighted Star Discrepancy

The ‘goodness’ of a set of quadrature points in [0, 1]d may be measured by the weighted star discrepancy. If the weights for the weighted star discrepancy are summable, then we show that for n prime there exist n-point rank-1 lattice rules whose weighted star discrepancy is O(n−1+δ) for any δ>0, where the implied constant depends on δ and the weights, but is independent of d and n. Further, we show that the generating vector z for such lattice rules may be obtained using a component-by-component construction. The results given here for the weighted star discrepancy are used to derive corresponding results for a weighted Lp discrepancy
Random noise in Diffusion Tensor Imaging, its Destructive Impact and Some Corrections

The empirical origin of random noise is described, its influence on DTI variables is illustrated by a review of numerical and in vivo studies supplemented by new simulations investigating high noise levels. A stochastic model of noise propagation is presented to structure noise impact in DTI. Finally, basics of voxelwise and spatial denoising procedures are presented. Recent denoising procedures are reviewed and consequences of the stochastic model for convenient denoising strategies are discussed.
Semiparametric Stepwise Regression to Estimate Sales Promotion Effects

Kalyanam and Shively (1998) and van Heerde et al. (2001) have proposed semiparametric models to estimate the influence of price promotions on brand sales, and both obtained superior performance for their models compared to strictly parametric modeling. Following these researchers, we suggest another semiparametric framework which is based on penalized B-splines to analyze sales promotion effects flexibly. Unlike these researchers, we introduce a stepwise procedure with simultaneous smoothing parameter choice for variable selection. Applying this stepwise routine enables us to deal with product categories with many competitive items without imposing restrictions on the competitive market structure in advance. We illustrate the new methodology in an empirical application using weekly store-level scanner data.
Current-Induced Effects in Nanoscale Conductors

We present an overview of current-induced effects in nanoscale conductors
with emphasis on their description at the atomic level. In particular, we
discuss steady-state current fluctuations, current-induced forces, inelastic
scattering and local heating. All of these properties are calculated in terms
of single-particle wavefunctions computed using a scattering approach within
the static density-functional theory of many-electron systems. Examples of
current-induced effects in atomic and molecular wires will be given and
comparison with experimental results will be provided when available.Comment: revtex, 10 pages, 8 figure
Sthenic incompatibilities in rigid bodies motion

When a rigid body slides with friction on a surface, hopping motion is observed: this is an everyday phenomenon. In rigid bodies mechanics, this phenomenon appears when it is no longer possible to compute the reaction contact forces. The difficulty is overcome by a motion theory involving velocity discontinuities. Velocity discontinuities may result either from an obstacle which makes impossible to compute the acceleration: this is a cinematic incompatibility or from the impossibility to compute the reaction forces: this is a sthenic incompatibility. We describe two examples: the Klein and PainlevÃ© sthenic incompatibilities. Springer 2006
Manifestation of Chaos in Real Complex Systems: Case of Parkinson's
  Disease

In this chapter we present a new approach to the study of manifestations of
chaos in real complex system. Recently we have achieved the following result.
In real complex systems the informational measure of chaotic chatacter (IMC)
can serve as a reliable quantitative estimation of the state of a complex
system and help to estimate the deviation of this state from its normal
condition. As the IMC we suggest the statistical spectrum of the non-Markovity
parameter (NMP) and its frequency behavior. Our preliminary studies of real
complex systems in cardiology, neurophysiology and seismology have shown that
the NMP has diverse frequency dependence. It testifies to the competition
between Markovian and non-Markovian, random and regular processes and makes a
crossover from one relaxation scenario to the other possible. On this basis we
can formulate the new concept in the study of the manifestation of chaoticity.
We suggest the statistical theory of discrete non-Markov stochastic processes
to calculate the NMP and the quantitative evaluation of the IMC in real complex
systems. With the help of the IMC we have found out the evident manifestation
of chaosity in a normal (healthy) state of the studied system, its sharp
reduction in the period of crises, catastrophes and various human diseases. It
means that one can appreciably improve the state of a patient (of any system)
by increasing the IMC of the studied live system. The given observation creates
a reliable basis for predicting crises and catastrophes, as well as for
diagnosing and treating various human diseases, Parkinson's disease in
particular.Comment: 20 pages, 8 figures, 3 tables. To be published in "The Logistic Map
  and the Route to Chaos: From the Beginnings to the Modern Applications", eds.
  by M. Ausloos, M. Dirickx, pp. 175-196, Springer-Verlag, Berlin (2006
Influence of information flow in the formation of economic cycles

A microscopic approach to macroeconomic features is intended. A model for
macroeconomic behavior based on the Ausloos-Clippe-Pekalski model is built and
investigated. The influence of a discrete time information transfer is
investigated. The formation of economic cycles is observed as a function of the
time of information delay. Three regions of delay time are recognized: short
$t_d \in (2 IS, 4 IS)$ (IS - iteration steps) - the system evolves toward a
unique stable equilibrium state, medium $t_d =5 IS $ or $t_d =6 IS $, the
system undergoes oscillations: stable concentration cycles appear in the
system. For long information flow delay times, $t_d \geq 7$, the systems may
crash for most initial concentrations. However, even in the case of long delay
time the crash time may be long enough to allow observation of the system
evolution and to introduce an appropriate strategy in order to avoid the
collapse of the e.g. company concentration. In the long time delay it is also
possible to observe an "economy resonance" where despite a long delay time the
system evolves for a long time or can even reach a stable state, which insures
its existence.Comment: 18 pages,16 figures, to be published in Verhulst 200 Proceedings, M.
  Ausloos and M. Dirickx, Eds. (in press
A recent appreciation of the singular dynamics at the edge of chaos

We study the dynamics of iterates at the transition to chaos in the logistic
map and find that it is constituted by an infinite family of Mori's $q$-phase
transitions. Starting from Feigenbaum's $\sigma $ function for the diameters
ratio, we determine the atypical weak sensitivity to initial conditions $\xi
_{t}$ associated to each $q$-phase transition and find that it obeys the form
suggested by the Tsallis statistics. The specific values of the variable $q$ at
which the $q$-phase transitions take place are identified with the specific
values for the Tsallis entropic index $q$ in the corresponding $\xi_{t}$. We
describe too the bifurcation gap induced by external noise and show that its
properties exhibit the characteristic elements of glassy dynamics close to
vitrification in supercooled liquids, e.g. two-step relaxation, aging and a
relationship between relaxation time and entropy.Comment: Proceedings of: Verhulst 200 on Chaos, Brussels 16-18 September 2004,
  Springer Verlag, in pres