pinecone/core-2020-05-10-deduplication huggingface dataset:
Reconstructions of diamond (100) and (111) surfaces: Accuracy of the
  Brenner potential

We present a detailed comparison of the structural predictions of the
effective many-body Brenner potential with those of ab-initio studies for known
reconstructions of diamond (100) and (111) surfaces. These results suggest high
reliability of the Brenner potential for dealing with carbon-based structures
where different types of bonding are present at the same time.Comment: 8 pages, 2 figures, conference paper to appear in Physica Status
  Solidi (a), we give a support of our recent predictions for diamond(111),
  [see Phys. Rev. B (Rapid Comm.), in press, cond-mat/0001397 and
  http://www.sci.kun.nl/tvs/carbon/meta.html
Renormalization of the Optical Response of Semiconductors by
  Electron-Phonon Interaction

In the past five years enormous progress has been made in the ab initio
calculations of the optical response of electrons in semiconductors. The
calculations include the Coulomb interaction between the excited electron and
the hole left behind, as well as local field effects. However, they are
performed under the assumption that the atoms occupy fixed equilibrium
positions and do not include effects of the interaction of the lattice
vibrations with the electronic states (electron-phonon interaction). This
interaction shifts and broadens the energies at which structure in the optical
spectra is observed, the corresponding shifts being of the order of the
accuracy claimed for the ab initio calculations. These shifts and broadenings
can be calculated with various degrees of reliability using a number of
semiempirical and ab initio techniques, but no full calculations of the optical
spectra including electron-phonon interaction are available to date.
  This article discusses experimental and theoretical aspects of the
renormalization of optical response functions by electron-phonon interaction,
including both temperature and isotopic mass effects. Some of the theoretical
techniques used can also be applied to analyze the renormalization of other
response functions, such as the phonon spectral functions, the lattice
parameters, and the elastic constants.Comment: Latex 2.09, 28 pages, 13 Figs., 2 Tables, submitted to Phys. Stat.
  Sol.
Two-dimensional topological solitons in rectangular magnetic dots

A general approach allowing to find the analytical expressions for
equilibrium magnetic structures in small and flat magnetic nano-sized cylinders
of arbitrary shape made of soft magnetic material is presented. The resulting
magnetization distributions are two-dimensional topological solitons and have a
non-zero topological charge. The approach is illustrated here on an example of
a thin rectangular particle.Comment: 3 pages, 2 figures, RevTex, for SCM2001 (Seeheim, Germany, 2001),
  satellite of JEMS'01 conferenc
Kirchhoff's Rule for Quantum Wires. II: The Inverse Problem with
  Possible Applications to Quantum Computers

In this article we continue our investigations of one particle quantum
scattering theory for Schroedinger operators on a set of connected (idealized
one-dimensional) wires forming a graph with an arbitrary number of open ends.
The Hamiltonian is given as minus the Laplace operator with suitable linear
boundary conditions at the vertices (the local Kirchhoff law). In ``Kirchhoff's
rule for quantum wires'' [J. Phys. A: Math. Gen. 32, 595 - 630 (1999)] we
provided an explicit algebraic expression for the resulting (on-shell) S-matrix
in terms of the boundary conditions and the lengths of the internal lines and
we also proved its unitarity. Here we address the inverse problem in the
simplest context with one vertex only but with an arbitrary number of open
ends. We provide an explicit formula for the boundary conditions in terms of
the S-matrix at a fixed, prescribed energy. We show that any unitary $n\times
n$ matrix may be realized as the S-matrix at a given energy by choosing
appropriate (unique) boundary conditions. This might possibly be used for the
design of elementary gates in quantum computing. As an illustration we
calculate the boundary conditions associated to the unitary operators of some
elementary gates for quantum computers and raise the issue whether in general
the unitary operators associated to quantum gates should rather be viewed as
scattering operators instead of time evolution operators for a given time
associated to a quantum mechanical Hamiltonian.Comment: 16 page
Non-commutative D- and M-brane Bound States

We analyze certain brane bound states in M-theory and their descendants in type IIA string theory, all involving 3-form or 2-form background fluxes. Among them are configurations which represent NCYM, NCOS and ODp-theories in the scaling limit of OM-theory. In particular, we show how the conditions for the embedding to preserve supersymmetry are modified by the presence of the flux and discuss their relations for the various different bound states. Via the formalism of geometric quantization such a deformation of a supersymmetric cycle is related to a non-commutativity of its coordinates. We also study possible non-commutative deformations of the Seiberg-Witten curve of N=2 supersymmetric gauge theories due to non-trivial H-flux
Non-commutative D- and M-brane Bound States

We analyze certain brane bound states in M-theory and their descendants in
type IIA string theory, all involving 3-form or 2-form background fluxes. Among
them are configurations which represent NCYM, NCOS and ODp-theories in the
scaling limit of OM-theory. In particular, we show how the conditions for the
embedding to preserve supersymmetry are modified by the presence of the flux
and discuss their relations for the various different bound states. Via the
formalism of geometric quantization such a deformation of a supersymmetric
cycle is related to a non-commutativity of its coordinates. We also study
possible non-commutative deformations of the Seiberg-Witten curve of N=2
supersymmetric gauge theories due to non-trivial H-flux.Comment: 21 pages, latex, 1 figure, revised version contains additional ref
Strings, Branes and Extra Dimensions

This review is devoted to strings and branes. Firstly, perturbative string theory is introduced. The appearance of various types of branes is discussed. These include orbifold fixed planes, D-branes and orientifold planes. The connection to BPS vacua of supergravity is presented afterwards. As applications, we outline the role of branes in string dualities, field theory dualities, the AdS/CFT correspondence and scenarios where the string scale is at a TeV. Some issues of warped compactifications are also addressed. These comprise corrections to gravitational interactions as well as the cosmological constant problem
Lectures on Supergravity

The text is an essentially self-contained introduction to four-dimensional N=1 supergravity, including its couplings to super Yang-Mills and chiral matter multiplets, for readers with basic knowledge of standard gauge theories and general relativity. Emphasis is put on showing how supergravity fits in the general framework of gauge theories and how it can be derived from a tensor calculus for gauge theories of a standard form. Contents: 1. Introduction, 2. Gauge symmetries in the jet space approach, 3. D=4, N=1 pure supergravity, 4. Tensor calculus for standard gauge theories, 5. Off-shell formulations of D=4, N=1 supergravity with matter, A. Lorentz algebra, spinors, Grassmann parity, B. Explicit verification of local supersymmetry
Electric microfield distribution in two-component plasmas: Theory and Simulations

The distribution of the electric microfield at a charged particle moving in a two-component plasma is calculated. The theoretical approximations are obtained via the parameter integration technique and using the screened pair approximation for the generalized radial distribution function. It is shown that the two-component plasma microfield distribution shows a larger probability of high microfield values than the corresponding distribution of the commonly used OCP model. The theory is checked by quasiclassical molecular-dynamics simulations. For the simulations a corrected Kelbg pseudopotential has been used
Electric microfield distribution in two-component plasmas. Theory and
  Simulations

The distribution of the electric microfield at a charged particle moving in a
two-component plasma is calculated. The theoretical approximations are obtained
via the parameter integration technique and using the screened pair
approximation for the generalized radial distribution function. It is shown
that the two-component plasma microfield distribution shows a larger
probability of high microfield values than the corresponding distribution of
the commonly used OCP model. The theory is checked by quasiclassical
molecular-dynamics simulations. For the simulations a corrected Kelbg
pseudopotential has been used.Comment: 24 pages, 5 figures, to be published in Contr. to Plasma Physic
Plasmon dispersion of a weakly degenerate nonideal one-component plasma

Classical Molecular Dynamics simulations (MD) for a one-component weakly
degenerate plasma are presented. Using an effective quantum pair potential
(Kelbg potential), the dynamic structure factor and the dispersion of Langmuir
waves are computed. The influence of the coupling strength
  $\Gamma$ and degree of degeneracy $\rho \Lambda^3$ on these properties is
discussed. The results are compared with predictions of mean-field theories.Comment: 5 pages, 3 eps figures, uses cpp2e style (included), submitted to
  Contrib. Plasma Phy
Magnetic deformation of the white dwarf surface structure

The influence of strong, large-scale magnetic fields on the structure and temperature distribution in white dwarf atmospheres is investigated. Magnetic fields may provide an additional component of pressure support, thus possibly inflating the atmosphere compared to the non-magnetic case. Since the magnetic forces are not isotropic, atmospheric properties may significantly deviate from spherical symmetry. In this paper the magnetohydrostatic equilibrium is calculated numerically in the radial direction for either for small deviations from different assumptions for the poloidal current distribution. We generally find indication that the scale height of the magnetic white dwarf atmosphere enlarges with magnetic field strength and/or poloidal current strength. This is in qualitative agreement with recent spectropolarimetric observations of Grw$+10\degr8247$. Quantitatively, we find for e.g. a mean surface poloidal field strength of 100 MG and a toroidal field strength of 2-10 MG an increase of scale height by a factor of 10. This is indicating that already a small deviation from the initial force-free dipolar magnetic field may lead to observable effects. We further propose the method of finite elements for the solution of the two-dimensional magnetohydrostatic equilibrium including radiation transport in the diffusive approximation. We present and discuss preliminary solutions, again indicating on an expansion of the magnetized atmosphere
Distribution of Dark Matter around a Central Body, Pioneer Effect and
  Fifth Force

Within the framework of the Projective Unified Field Theory the distribution
of a dark matter gas around a central body is calculated. As a result the
well-known formulas of the Newtonian gravitational interaction are altered.
This dark matter effect leads to an additional radial force (towards the
center) in the equation of motion of a test body, being used for the
explanation of the so-called ``Pioneer effect'', measured in the solar system,
but without a convincing theoretical basis up to now. Further the relationship
of the occurring new force to the so-called ``fifth force'' is discussed.Comment: 11 pages, 7 figures, LaTe
Occurrence of crude oil degrading bacteria in gasoline and diesel station soils

Microbial enumeration and identification were carried out on several oil contaminated soil samples collected from gasoline and diesel stations. Bacteria were the most dominant microbiota and were therefore classified to generic level. Eleven main genera were detected and Corynebacterium was the predominant genus in all the samples. Biochemical characterisation and substrate utilisation showed high percentage of lipolytic ability combined with high inorganic nitrogen utilisers. The ability of these cultures to degrade crude oil was tested individually and in mixed bacterial consortium at different temperatures and pH values. Maximum crude oil biodegradation of 78% was achieved using a bacterial consortium containing five cultures (Micrococcus sp. GS2-22, Corynebacterium sp. GS5-66, Flavobacterium sp. DS5-73, Bacillus sp. DS6-86 and Pseudomonas sp. DS10-129) with 1% crude oil at 30 °C and pH 7.5. Such a consortium may be useful for bioaugmentation of oil contaminated environments
Line-Fitting by rotation: A nonparametric method for bivariate allometric analysis

The choice of an appropriate method for fitting a straight line to data is one of the major procedural problems in bivariate allometric analysis. Commonly used techniques, such as ordinary least-squares regression and major axis, are derived from the general structural relationship model and thus require some knowledge about the distribution of the data. In this paper, we explore a nonparametric alternative, referred to as “rotation method”, which involves no assumptions about error distributions. It is symmetrical in the two variables and highly resistant against the influence of outlying data points. In this initial study, eight alternative versions of line-fitting by rotation are compared, using simulated data. The versions with the best overall performance are applied to empirical data from selected examples in biological anthropology. A comparison with conventional parametric methods reveals some marked advantages of the rotation method for descriptive allometric studies, indicating that further investigation into procedures of this kind is clearly warranted
A comparative analysis of graphical interaction and logistic regression modelling: self-care and coping with a chronic illness in later life

Quantitative research especially in the social, but also in the biological sciences has been limited by the availability and applicability of analytic techniques that elaborate interactions among behaviours, treatment effects, and mediating variables. This gap has been filled by a newly developed statistical technique, known as graphical interaction modelling. The merit of graphical models for analyzing highly structured data is explored in this paper by an empirical study on coping with a chronic condition as a function of interrelationships between three sets of factors. These include background factors, illness context factors and four self--care practices. Based on a graphical chain model, the direct and indirect dependencies are revealed and discussed in comparison to the results obtained from a simple logistic regression model ignoring possible interaction effects. Both techniques are introduced from a more tutorial point of view instead of going far into technical details.
Hybrid Organic-Inorganic Materials - In Search of Synergic Activity

This review surveys the work developed in the field of functional hybrid materials, especially those containing conducting organic polymers (COPs), in combination with a variety of inorganic species, from molecular to extended phases, including clusters and nano-sized inorganic particles. Depending on the dominating structural matrix, we distinguish and analyze organic-inorganic (OI) hybrids, nanocomposite materials, and inorganic-organic (IO) phases. These materials have been used in a wide variety of applications, including energy-storage applications, electrocatalysis, the harnessing of electrochromic and photoelectrochromic properties, application in display devices, photovoltaics, and novel energy-conversion systems, proton-pump electrodes, sensors, or chemiresistive detectors, which work as artificial noses.Financial support from CICYT (Spain) (MAT98-0807-C02-02) is acknowledged.Peer reviewe
Kinetics of electrocrystallization of PbO2 on glassy carbon electrodes: influence of electrode rotation

Electrodeposition of PbO2 on glassy carbon electrodes was studied in stationary conditions and on the rotating disk electrode using chronoamperometric technique. The kinetics of electrodeposition was significantly retarded by the hydrodynamic mass transport flow. This observation is in agreement with the mechanism involving formation of soluble Pb(III) or Pb(IV) species, which may, subsequently, form PbO2. The kinetics of the nucleation and crystal growth was determined by the analysis of the initial part of the transients and of the whole curves. This process proceeds through the 3 dimensional progressive nucleation and crystal growth mechanism with an induction time. The growth rate constant is strongly affected by convection while the nucleation process and the induction time are much less influenced.Consellería de Cultura, Educación y Ciencia (project GV-2231-94)
Surface Catalytic Mechanism in Square-Wave Voltammetry

A pseudo-first-order catalytic mechanism in which both reactant and product of the redox reaction are strongly immobilized on the electrode\ud
surface is theoretically analyzed under conditions of square-wave voltammetry (SWV). A mathematical procedure is developed for diffusionless\ud
conditions. The relationships between the properties of the voltammetric response and both the kinetic parameters of the redox\ud
reaction and the parameters of the excitement signal are studied. The phenomenon of the quasireversible maximum is discussed. The\ud
theoretical results are confirmed with the experiments of azobenzene performed in a presence of hydrogen peroxide. In acetate buffer with\ud
pH 4.2 the standard rate constant of charge transfer of azobenzene is ks ¼ 12 s�1 and the catalytic rate constant in the presence of hydrogen\ud
peroxide is kc ¼ 2.246104 s�1 mol�1 L
Square-Wave Voltammetry of a Second Order Cathodic Stripping Process Coupled by Adsorption of the Reacting Ligand

A new theory of a second order cathodic stripping reaction accompanied by adsorption of the reacting ligand is\ud
developed under conditions of square-wave voltammetry. In the mathematical model, the following reaction is\ud
considered:\ud
2L� (ads)�2L�(aq)�Hg(l)�HgL2(s)�2e�\ud
The relationships between the properties of the voltammetric response and both the kinetic parameters as well as the\ud
parameters of the excitement signal were analyzed. Both reversible and quasireversible redox reactions were\ud
examined. Criterions for distinguishing the studied mechanism from the other types of cathodic stripping reactions\ud
were established. The phenomenon of a quasireversible maximum was studied in details. The theoretical results are\ud
qualitatively compared with the SW voltammograms of 6-propyl-2-thiouracil
Characterization of airborne particles and droplets: Relation to amount of airborne dust and dust collection efficiency

Water sprays have been commonly used to suppress airborne dust. Water is doped with surface-active agents to enhance the dust capture efficiency through a reduction of surface tension. Nevertheless, dust collection efficiencies have been less than satisfactory historically. A detailed characterization of freshly generated airborne dust particles and spray droplets was carried out in order to explain this observation. Such properties as the agglomeration state of the freshly generated airborne dust particles and the airborne dust production capacity of various materials were defined and quantified. Electrostatic charges on individual airborne particles and spray droplets were measured. It was demonstrated that freshly generated airborne dust particles were extensively agglomerated. The magnitude of agglomeration was a function of material type and decided the amount of dust becoming airborne from a given material. This explains why certain materials such as quartz and anthracite produce more dust than some others. It was demonstrated that surfactants could be employed to charge the spray droplets selectively. The sign and magnitude of the droplet charge was a function of surfactant type and concentration. A strong correlation between the droplet charge and dust collection efficiencies by spray droplets was observed for cationic surfactants, suggesting that surfactants affected collection efficiency in addition to enhancing wetting
Moment Sets of Bell-Shaped Distributions: Extreme Points, Extremal Decomposition and Chebysheff Inequalities

The paper deals with sets of distributions which are given by moment conditions for the distributions and convex constraints on derivatives of their c.d.fs. A general albeit simple method for the study of their extremal structure, extremal decomposition and topological or measure theoretical properties is developed. Its power is demonstrated by the application to bell-shaped distributions. Extreme points of their moment sets  are characterized completely (thus filling a gap in the previous theory) and inequalities of Tchebysheff type are derived by means of general integral representation theorems. 
 Some key words: Moment sets, Tschebysheff inequalities, extremal bell-shaped distributions
Measures of Fermi surfaces and absence of singular continuous spectrum
  for magnetic Schroedinger operators

Fermi surfaces are basic objects in solid state physics and in the spectral
theory of periodic operators. We define several measures connected to Fermi
surfaces and study their measure theoretic properties. From this we get absence
of singular continuous spectrum and of singular continuous components in the
density of states for symmetric periodic elliptic differential operators acting
on vector bundles. This includes Schroedinger operators with periodic magnetic
field and rational flux, as well as the corresponding Pauli and Dirac-type
operators.Comment: 19 page
Dual group actions on C*-algebras and their description by Hilbert extensions

17 pages, no figures.-- MSC1991 codes: 47L65, 22D25, 46L40 (primary), 81T05 (secondary).MR#: MR1905661 (2003m:46101)Zbl#: Zbl 1002.22002Given a C*-algebra $A$, a discrete abelian group $X$ and a homomorphism $\Theta: X\to$ Out$A$ defining the dual action group $\Gamma\subset$ aut$A$, the paper contains results on existence and characterization of Hilbert $\{A,\Gamma\}$, where the action is given by $\hat{X}$. They are stated at the (abstract) C*-level and can therefore be considered as a refinement of the extension results given for von Neumann algebras for example by Jones [Mem.Am.Math.Soc. 28 Nr 237 (1980)] or Sutherland [Publ.Res.Inst.Math.Sci. 16 (1980) 135]. A Hilbert extension exists iff there is a generalized 2-cocycle. These results generalize those in [Commun.Math.Phys. 15 (1969) 173], which are formulated in the context of superselection theory, where it is assumed that the algebra $A$ has a trivial center, i.e. $Z=C1$. In particular the well-known ``outer characterization'' of the second cohomology $H^2(X,{\cal U}(Z),\alpha_X)$ can be reformulated: there is a bijection to the set of all $A$-module isomorphy classes of Hilbert extensions. Finally, a Hilbert space representation (due to Sutherland in the von Neumann case) is mentioned. The C*-norm of the Hilbert extension is expressed in terms of the norm of this representation and it is linked to the so-called regular representation appearing in superselection theory.The second author (F.Ll.) expresses his gratitude to Sergio Doplicher for his hospitality at the ‘Dipartamento di Matematica dell’Università di Roma "La Sapienza" in october’99. The visit was supported by a EU TMR network "Implementation of concept and methods from Non–Commutative Geometry to Operator Algebras and its applications”, contract no. ERB FMRXCT 96-0073.Publicad