February 2006 arXiv papers — page 11

Gang Yan, Zhong-Qian Fu, Jie Ren, Wen-Xu Wang

Much recent empirical evidence shows that \textit{community structure} is ubiquitous in the real-world networks. In this Letter, we propose a growth model to create scale-free networks with the tunable strength (noted by $Q$) of community structure and investigate the influence of community strength upon the collective synchronization induced by SIRS epidemi

Hartmann Roemer

Process Philosophy endeavours to replace the classical ontology of substances by a process ontology centered on notions of changes and transitions. We argue, that the substantial and processual approach are mutually complementary. Here, complementarity is to be understood in the sense of a "Generalized Quantum Theory", which is not restricted to physical phe

Michael A. Armen, Hideo Mabuchi

The interplay of quantum fluctuations with nonlinear dynamics is a central topic in the study of open quantum systems, connected to fundamental issues (such as decoherence and the quantum-classical transition) and practical applications (such as coherent information processing and the development of mesoscopic sensors/amplifiers). With this context in mind,

Guang-Hao Low, Zhiming Shi, Ye Yeo

We consider the collision model of Ziman {\em et al.} and study the robustness of $N$-qubit Greenberger-Horne-Zeilinger (GHZ), W, and linear cluster states. Our results show that $N$-qubit entanglement of GHZ states would be extremely fragile under collisional decoherence, and that of W states could be more robust than of linear cluster states. We indicate t

J. Y. Vaishnav, A. Itsara, E. J. Heller

This paper develops a scattering theory to examine how point impurities affect transport through quantum wires. While some of our new results apply specifically to hard-walled wires, others--for example, an effective optical theorem for two-dimensional waveguides--are more general. We apply the method of images to the hard-walled guide, explicitly showing ho

A. De Gregorio, S. Esposito

We report on theoretical courses by Fermi and Majorana, giving evidence of the first appearance and further development of Quantum Mechanics teaching in Italy. On the basis of original documents, we make a comparison between Fermi's and Majorana's approaches. A detailed analysis is carried out of Fermi's course on Theoretical Physics attended by

V. Dorobantu

As a starting point in understanding Quantum Mechanics, the postulates of Quantum Mechanics are presented, and few of the main eigenvalue problems, as well.

Francisco A. Rodrigues, Gonzalo Travieso, Luciano da F. Costa

A new method for community identification is proposed which is founded on the analysis of successive neighborhoods, reached through hierarchical growth from a starting vertex, and on the definition of communities as a subgraph whose number of inner connections is larger than outer connections. In order to determine the precision and speed of the method, it i

A. Calcaterra, R. de Sangro, G. Mannocchi, P. Patteri

In this paper we propose a new concept for streamer quenching in Resistive Plate Chambers (RPCs). In our approach, the multiplication process is quenched by the appropriate design of a mechanical structure inserted between the two resistive electrodes. We show that stable performance is achieved with binary gas mixtures based on argon and a small fraction of

Michael C. Wittmann, Jeffrey T. Morgan, Roger E. Feeley

We report on the development of students' ideas of probability and probability density in a University of Maine laboratory-based general education physics course called Intuitive Quantum Physics. Students in the course are generally math phobic with unfavorable expectations about the nature of physics and their ability to do it. We describe a set of acti

M. Tessarotto, M. Ellero

Fundamental aspects of inverse kinetic theories for the incompressible Navier-Stokes equations [Ellero and Tessarotto, 2004, 2005] include the possibility of defining uniquely the kinetic equation underlying such models and furthermore, the construction of a kinetic theory implying also the energy equation. The latter condition is consistent with the require

Xuguang Chi, Wuyi Hsiang, Ping Sheng

We present a non-variational, kinetic energy operator approach to the solution of quantum three-body problem with Coulomb interactions, based on the utilization of symmetries intrinsic to the kinetic energy operator, i.e., the three-body Laplacian operator with the respective masses. Through a four-step reduction process, the nine dimensional problem is redu

P. K. Panda, João da Providência, Constança Providência

Short range correlations are introduced using unitary correlation method in a relativistic approach to the equation of state of the infinite nuclear matter in the framework of the Hartree-Fock approximation. It is shown that the correlations give rise to an extra node in the ground-state wave-function in the nucleons, contrary to what happens in non-relativi

Gerald A Miller, Allena K. Opper, Edward J. Stephenson

Charge symmetry breaking (CSB) in the strong interaction occurs because of the difference between the masses of the up and down quarks. The use of effective field theories allows us to follow this influence of confined quarks in hadronic and nuclear systems. The progress in observing and understanding CSB is reviewed with particular attention to the recent s

Xavier Leoncini, Leonid Kuznetsov, George M. Zaslavsky

Advection properties of passive particles in flows generated by point vortices are considered. Transport properties are anomalous with characteristic transport exponent $μ\sim 1.5$. This behavior is linked back to the presence of coherent fractal structures within the flow. A fractional kinetic analysis allows to link the characteristic transport exponent $μ

Xavier Leoncini, George M. Zaslavsky

The problem of characterizing the origin of the non-Gaussian properties of transport resulting from Hamiltonian dynamics is addressed. For this purpose the notion of chaotic jet is revisited and leads to the definition of a diagnostic able to capture some singular properties of the dynamics. This diagnostic is applied successfully to the problem of advection

Thomas Y. Hou, Ruo Li

We study the interplay between the local geometric properties and the non-blowup of the 3D incompressible Euler equations. We consider the interaction of two perturbed antiparallel vortex tubes using Kerr's initial condition \cite{Kerr93}[Phys. Fluids {\bf 5} (1993), 1725]. We use a pseudo-spectral method with resolution up to $1536\times 1024 \times 307

Jingsong He, Yi Cheng, Rudolf A. Roemer

We present a systematic way to construct solutions of the (n=5)-reduction of the BKP and CKP hierarchies from the general tau function of the KP hierarchy. We obtain the one-soliton, two-soliton, and periodic solution for the bi-directional Sawada-Kotera (bSK), the bi-directional Kaup-Kupershmidt (bKK) and also the bi-directional Satsuma-Hirota (bSH) equatio

Ingrid Bauer, Fabrizio Catanese, Roberto Pignatelli

Chapters : Old and new inequalities; Surfaces with $χ=1$ and the bicanonical map; Surfaces with $p_g=4$; Surfaces isogeneous to a product, Beauville surfaces and the absolute Galois group;Lefschetz pencils and braid monodromies;DEF, DIFF and other equivalence relations.

Satyan L. Devadoss, John Mugno

Using a simplistic model of juggling based on physics, a natural map is constructed from the set of periodic juggling patterns (or site swaps) to links. We then show that all topological links can be juggled.

R. Hind, A. Ivrii

We show that all Lagrangian submanifolds of the cotangent bundle of a Riemann surface which are homotopic to the zero section must be smoothly isotopic to the zero section.

Zoltan I. Szabo

By a recent observation, the Laplacians on the Riemannian manifolds the author used for isospectrality constructions are nothing but the Zeeman-Hamilton operators of free charged particles. These manifolds can be considered as prototypes of the so called Zeeman manifolds. This observation allows to develop a spectral theory both on open Z-manifolds and their

Donald M. Davis

We prove the following two new optimal immersion results for complex projective space. First, if n equiv 3 mod 8 but n not equiv 3 mod 64, and alpha(n)=7, then CP^n can be immersed in R^{4n-14}. Second, if n is even and alpha(n)=3, then CP^n can be immersed in R^{4n-4}. Here alpha(n) denotes the number of 1's in the binary expansion of n. The first contr

M. J. Alvarez, A. Gasull, H. Giacomini

A solution of the Abel equation $\dot{x}=A(t)x^3+B(t)x^2$ such that $x(0)=x(1)$ is called a periodic orbit of the equation. Our main result proves that if there exist two real numbers $a$ and $b$ such that the function $aA(t)+bB(t)$ is not identically zero, and does not change sign in $[0,1]$ then the Abel differential equation has at most one non-zero perio

Richard Randell, Jonathan Simon, Joshua Tokle

The image of a polygonal knot K under a spherical inversion of R^3 (union infinity) is a simple closed curve made of arcs of circles, having the same knot type as the mirror image of K. Suppose we reconnect the vertices of the inverted polygon with straight lines, making a new polygon. This may be a different knot type. For example, a certain 7-segment figur

Liqing Yan

A Milstein-type scheme was proposed to improve the rate of convergence of its approximation of the solution to a stochastic differential equation driven by a vector of continuous semimartingales. A necessary and sufficient condition was provided for this rate to be $1/n$ when the SDE is driven by a vector of continuous local martingales, or continuous semima

Vincent Schmitt

We use a generic notion of flatness in the enriched context to define various completions of metric spaces -- enrichments over [0,\infty] -- and preorders -- enrichments over 2. We characterize the weights of colimits commuting in [0,\infty] with the terminal object and cotensors. These weights can be intrepreted in metric terms as peculiar filters, the so-c

Bruno Bouchard, Nicole El Karoui, Nizar Touzi

We study a maturity randomization technique for approximating optimal control problems. The algorithm is based on a sequence of control problems with random terminal horizon which converges to the original one. This is a generalization of the so-called Canadization procedure suggested by Carr [Review of Financial Studies II (1998) 597--626] for the fast comp

Henrik Hult, Filip Lindskog, Thomas Mikosch, Gennady Samorodnitsky

We extend classical results by A. V. Nagaev [Izv. Akad. Nauk UzSSR Ser. Fiz.--Mat. Nauk 6 (1969) 17--22, Theory Probab. Appl. 14 (1969) 51--64, 193--208] on large deviations for sums of i.i.d. regularly varying random variables to partial sum processes of i.i.d. regularly varying vectors. The results are stated in terms of a heavy-tailed large deviation prin

Bernard Delyon, Ying Hu

In this paper, we propose some algorithms for the simulation of the distribution of certain diffusions conditioned on terminal point. We prove that the conditional distribution is absolutely continuous with respect to the distribution of another diffusion which is easy for simulation, and the formula for the density is given explicitly.

Mark Kambites, Pedro V. Silva, Benjamin Steinberg

We use language theory to study the rational subset problem for groups and monoids. We show that the decidability of this problem is preserved under graph of groups constructions with finite edge groups. In particular, it passes through free products amalgamated over finite subgroups and HNN extensions with finite associated subgroups. We provide a simple pr

Patrick Cheridito, H. Mete Soner, Nizar Touzi

We study the small time path behavior of double stochastic integrals of the form $\int_0^t(\int_0^rb(u) dW(u))^T dW(r)$, where $W$ is a $d$-dimensional Brownian motion and $b$ is an integrable progressively measurable stochastic process taking values in the set of $d\times d$-matrices. We prove a law of the iterated logarithm that holds for all bounded progr

Marek Golasinski, Daciberg Lima Goncalves

Let G be a finite group given in one of the forms listed in the title with period 2d and X(n) an n-dimensional CW-complex with the homotopy type of an n-sphere. We study the automorphism group Aut(G) to compute the number of distinct homotopy types of orbit spaces X(2dn-1)/μwith respect to free and cellular G-actions μon all CW-complexes X(2dn-1). At the end

Bruno Bouchard, Huyên Pham

We consider a general discrete-time financial market with proportional transaction costs as in [Kabanov, Stricker and Rásonyi Finance and Stochastics 7 (2003) 403--411] and [Schachermayer Math. Finance 14 (2004) 19--48]. In addition to the usual investment in financial assets, we assume that the agents can invest part of their wealth in industrial projects t

Nadia S. Larsen, Iain Raeburn

We present a new proof of a theorem of Mallat which describes a construction of wavelets starting from a quadrature mirror filter. Our main innovation is to show how the scaling function associated to the filter can be used to identify a certain direct limit of Hilbert spaces with $L^2(\R)$ in such a way that one can immediately identify the wavelet basis. O

Aaron Lauve

We present two new proofs of the the important q-commuting property holding among certain pairs of quantum minors of an n x n q-generic matrix. The first uses elementary quasideterminantal arithmetic; the second involves paths in an edge-weighted directed graph.

Nobuya Watanabe

We obtain results on the growth sequences of the differential for iterations of circle diffeomorphisms without periodic points.

Pascal Hubert, Martin Schmoll, Serge Troubetzkoy

For a Veech surface (x,ω), we characterize subspaces of X^n, invariant under the diagonal action of the affine group of X. We prove that non-arithmetic Veech surfaces have only finitely many invariant subspaces of very particular shape (in any dimension). Among other consequences we find copies of (X,ω) embedded in the moduli-space of translation surfaces. W

J. C. González- Dávila

This paper has been withdrawn by the author due to a crucial error related with the consideration of regular points

Leonardo Biliotti, Claudio Gorodski

We prove that the orbits of a polar action of a compact Lie group on a compact rank one symmetric space are tautly embedded with respect to Z_2-coefficients.

G. Bogveradze, L. P. Castro

Wiener-Hopf plus Hankel operators acting between Lebesgue spaces on the real line are studied in view of their invertibility, one sided-invertibility, Fredholm, and semi-Fredholm properties. This is done in two different cases: (i) when the Fourier symbols of the operators are unitary functions, and (ii) when the Fourier symbols are related with sectorial el

Vesselin Drensky

This is an improved version of the talk of the author given at the Antalya Algebra Days VII on May 21, 2005. We present an introduction to the theory of the invariants under the action of GL(n,C) by simultaneous conjugation of d matrices of size n x n. Then we survey some results, old or recent, obtained by a dozen of mathematicians, on minimal sets of gener

Thomas Krainer

This paper is a continuation of the investigation of resolvents of elliptic operators on conic manifolds from math.AP/0410178 and math.AP/0410176 to the case of manifolds with boundary and realizations of operators under boundary conditions. We prove the existence of sectors of minimal growth for realizations of boundary value problems for cone operators und

Frederik Witt

The primary aim of this thesis is to investigate metrics which are induced by a differential form and arise as a critical point of Hitchin's variational principle. Firstly, we investigate metrics associated with the structure group PSU(3) acting in its adjoint representation. We derive various obstructions to the existence of a topological reduction to P

Oliver C. Schnürer

We show that strictly convex surfaces expanding by the inverse Gauss curvature flow converge to infinity in finite time. After appropriate rescaling, they converge to spheres. We describe the algorithm to find our main test function.

Oliver C. Schnürer

We show that strictly convex surfaces contracting with normal velocity equal to |A|^2 shrink to a point in finite time. After appropriate rescaling, they converge to spheres. We indicate how we used a computer to find the main test function.

Roger Alperin, Benson Farb

Let G be a finitely generated linear group over a field of characteristic 0. Suppose that every solvable subgroup of G is polycyclic. Then the claim is made that any solvable subgroup of G is separable. This is proven for G=SL_n(Z). However, the proof of the main theorem in section 4 is incomplete.

Roman Bezrukavnikov

The paper is concerned with cohomology of the small quantum group at a root of unity, and of its upper triangular subalgebra, with coefficients in a tilting module. We relate it to a certain t-structure on the derived category of equivariant coherent sheaves on the Springer resolution, and to equivariant coherent IC sheaves on the nil-cone. The support of th

Shogo Aoyama

We discuss 2-dimmensional non-linear sigma-models on the Kaehler manifold G/H in the first order formalisim. Using the Berkovits method we explicitly construct the G-symmetry currents and primaries, when G/H are irreducible. It is a variant of the Wakimoto realization of the affine Lie algebra using a particular reducible Kaehler manifold G/U(1)^r with r the

Gerald V. Dunne, Marek Krasnansky

We develop integration-by-parts rules for Feynman diagrams involving massive scalar propagators in a constant background electromagnetic field, and use these to show that there is a simple diagrammatic interpretation of mass renormalization in the two-loop scalar QED Heisenberg-Euler effective action for a general constant background field. This explains why

Sakura Schafer-Nameki

The one-loop worldsheet quantum corrections to the energy of spinning strings on R x S^3 within AdS_5 x S^5 are reexamined. The explicit expansion in the effective 't Hooft coupling λ'= λ/J^2 is rigorously derived. The expansion contains both analytic and non-analytic terms in λ', as well as exponential corrections. Furthermore, we pin down the o

D. Bashkirov, G. Sardanashvily

The Ward identities are the relations which the complete Green functions of quantum fields satisfy if an original classical Lagrangian system is degenerate. A generic degenerate Lagrangian system of even and odd fields is considered. It is characterized by a hierarchy of reducible Noether identities and gauge supersymmetries parameterized by antifields and g

Pietro Menotti, Erik Tonni

We work out the perturbative expansion of quantum Liouville theory on the pseudosphere starting from the semiclassical limit of a background generated by heavy charges. By solving perturbatively the Riemann-Hilbert problem for the Poincare' accessory parameters, we give in closed form the exact Green function on the background generated by one finite cha

Li-Jie Zhang, Yu-Xiao Liu

In this paper, we investigate the spinor field realizations of the $W_{2,4}$ algebra, making use of the fact that the $W_{2,4}$ algebra can be linearized through the addition of a spin-1 current. And then the nilpotent BRST charges of the spinor non-critical $W_{2,4}$ string were built with these realizations.

Wang Shuang, Wu Shuang-Qing, Xie Fei, Dan Lin

We investigate the first law of thermodynamics in the case of the (2+1)-dimensional BTZ black holes and Kerr-de Sitter spacetimes, in particular, we focus on the integral mass formulas. It is found that by assuming the cosmological constant as a variable state parameter, both the differential and integral mass formulas of the first law of black hole thermody

S. Hossenfelder

The aim of this paper is to clarify the relation between three different approaches of theories with a minimal length scale: A modification of the Lorentz-group in the 'Deformed Special Relativity', theories with a 'Generalized Uncertainty Principle' and those with 'Modified Dispersion Relations'. It is shown that the first two are eq

B. C. Allanach, C. Grojean, P. Skands, E. Accomando

The work contained herein constitutes a report of the "Beyond the Standard Model'' working group for the Workshop "Physics at TeV Colliders", Les Houches, France, 2-20 May, 2005. We present reviews of current topics as well as original research carried out for the workshop. Supersymmetric and non-supersymmetric models are studied, as well

J. P. Lansberg, B. Pire, L. Szymanowski

We study the exclusive production of pi pi and rho pi in hard gamma* gamma scattering in the forward kinematical region where the virtuality of one photon provides us with a hard scale in the process. The newly introduced concept of Transition Distribution Amplitudes (TDA) is used to perform a QCD calculation of these reactions thanks to two simple models fo

Oscar Cata, Maarten Golterman, Santi Peris

We examine whether the fact that QCD is chirally invariant at short distances necessarily leads to the prediction that hadrons form approximate parity doublets, as has been recently put forward by Glozman and collaborators. We show that this is not the case, and we exhibit some of the pitfalls of trying to link the operator product expansion to the hadron sp

Gennaro Corcella, Volker Drollinger

We present the energy distribution of b-flavoured hadrons in top quark decay using the PYTHIA and HERWIG event generators, which we tune to LEP and SLD data. We find that fitting the string and cluster models is essential to reproduce the e+e- data and to reliably predict B-hadron production in top decay. We also compare the PYTHIA and HERWIG results with th

Kuang-Ta Chao

BES Collaboration has recently observed an enhancement near the $ωϕ$ threshold in the double OZI suppressed decay $J/ψ\toγωϕ$. This $ωϕ$ enhancement is probably due to a new $J^{PC}=0^{++}$ X(1812) state. We discuss a possible assignment that the X(1812) is a $ 1/\sqrt{2}(u\bar u+d\bar d)g$ (or $s\bar sg$) hybrid meson. We suggest further measurements to tes

Peter Z Skands

The last decade has seen the emergence of a wide range of automated calculations for supersymmetric extensions of the Standard Model. This guide contains a brief summary of these, with the main focus on hadron collider phenomenology, as well as a brief introduction to the so-called SUSY Les Houches Accord. See also the Les Houches Web Repository for BSM Tool

S. Balestra, S. Cecchini, F. Fabbri, G. Giacomelli

The search for rare particles in the cosmic radiation remains one of the main aims of non-accelerator particle astrophysics. Experiments at high altitude allow lower mass thresholds with respect to detectors at sea level or underground. The SLIM experiment is a large array of nuclear track detectors located at the Chacaltaya High Altitude Laboratory (5290 m

Marcin Jankiewicz, Anjan A. Sen

We study the possibility of occurrence of scalar hair with a non-canonical kinetic term for a static, spherically symmetric asymptotically flat black hole spacetime. We first obtain a general equation for this purpose and then consider various examples for the kinetic term $F(X)$ with $X=-{1\over{2}}\partial^μϕ\partial_μϕ$. Our study shows that for a tachyon

Tomohiro Inagaki

A scalar self-interacting theory non-linearly coupled with some power of the curvature have a possibility to explain the current smallness of the cosmological constant. Here one concentrate on a massless scalar field in the four-dimensional Fridmann-Robertson-Walker (FRW) spacetime with flat spatial part. One show the phase structure of radiative symmetry br

S. Thirukkanesh, S. D. Maharaj

We study the Einstein-Maxwell system of equations in spherically symmetric gravitational fields for static interior spacetimes. The condition for pressure isotropy is reduced to a recurrence equation with variable, rational coefficients. We demonstrate that this difference equation can be solved in general using mathematical induction. Consequently we can fi

Lev V. Prokhorov

It is shown that in the model [3,4] of quantum mechanics besides probability amplitudes, the Planck constant and the Fock space, the cosmological constant also appear in the natural way. The Poisson brackets are generalized for the case of kinetics.

Vincent Schmitt, Krzysztof Worytkiewicz

In this paper we show that classical notions from automata theory such as simulation and bisimulation can be lifted to the context of enriched categories. The usual properties of bisimulation are nearly all preserved in this new context. The class of enriched functors that correspond to functionnal bisimulations surjective on objects is investigated and appe

Ioannis Antonellis, Efstratios Gallopoulos

We explore a matrix-space model, that is a natural extension to the vector space model for Information Retrieval. Each document can be represented by a matrix that is based on document extracts (e.g. sentences, paragraphs, sections). We focus on the performance of this model for the specific case in which documents are originally represented as term-by-sente

Vladimir Deineko, Peter Jonsson, Mikael Klasson, Andrei Krokhin

In the maximum constraint satisfaction problem (MAX CSP), one is given a finite collection of (possibly weighted) constraints on overlapping sets of variables, and the goal is to assign values from a given finite domain to the variables so as to maximize the number (or the total weight, for the weighted case) of satisfied constraints. This problem is NP-hard

D. Di Castro, E. Cappelluti, M. Lavagnini, A. Sacchetti

We carried out Raman measurements on neutron-irradiated and Al-doped MgB$_2$ samples. The irradiation-induced topological disorder causes an unexpected appearance of high frequency spectral structures, similar to those observed in lightly Al-doped samples. Our results show that disorder-induced violations of the selection rules are responsible for the modifi

Luis Brey, H. A. Fertig

We study edges states of graphene ribbons in the quantized Hall regime, and show that they can be described within a continuum model (the Dirac equation) when appropriate boundary conditions are adopted. The two simplest terminations, zigzag and armchair edges, are studied in detail. For zigzag edges, we find that the lowest Landau level states terminate in

Pinaki Sengupta, Aditya Raghavan, Stephan Haas

The consequences of disorder on interacting bosons trapped in optical lattices are investigated by quantum Monte Carlo simulations. At small to moderate strengths of potential disorder a unique effect is observed: if there is a Mott plateau at the center of the trap in the clean limit, phase coherence {\it increases} as a result of disorder. The localization

Craig J. Fennie, Karin M. Rabe

We have studied the influence of magnetic order on the optical phonons of the geometrically frustrated spinel ZnCr$_2$O$_4$ from first-principles. By mapping the first-principles phonon calculations onto a Heisenberg-like model, we developed a method to calculate exchange derivatives and subsequently the spin-phonon couping parameter from first-principles. A

M. I. Auslender, M. I. Katsnelson

Using Feynman path integral technique estimations of the ground state energy have been found for a conduction electron interacting with order parameter fluctuations near quantum critical points. In some cases only \textit{singular} perturbation theory in the coupling constant emerges for the electron ground state energy. It is shown that an autolocalized sta

V. V. Dobrovitski, J. M. Taylor, M. D. Lukin

Techniques for coherent control of electron spin-nuclear spin interactions in quantum dots can be directly applied in spintronics and in quantum information processing. In this work we study numerically the interaction of electron and nuclear spins in the context of storing the spin-state of an electron in a collective state of nuclear spins. We take into ac

E. S. Hernández, F. Ancilotto, M. Barranco, R. Mayol

We present a complete calculation of the structure of liquid $^4$He confined to a concave nanoscopic wedge, as a function of the opening angle of the walls. This is achieved within a finite-range density functional formalism. The results here presented, restricted to alkali metal substrates, illustrate the change in meniscus shape from rather broad to narrow

H. Jirari, W. Pötz

A Markovian master equation describing the evolution of open quantum systems in the presence of a time-dependent external field is derived within the Bloch-Redfield formalism. It leads to a system--bath interaction which depends on the control field. Optimal control theory is used to select control fields which allow accelerated or decelerated system relaxat

Audrius Alkauskas, Alexis Baratoff, C. Bruder

The mechanism of adsorption of the 1,4,5,8-naphthalene-tetracarboxylic-dianhydride (NTCDA) molecule on the Ag(110) surface is elucidated on the basis of extensive density functional theory calculations. This molecule, together with its perylene counterpart, PTCDA, are archetype organic semiconductors investigated experimentally over the past 20 years. We fin

A. Fontana, F. Rossi, G. Viliani, S. Caponi

We report new inelastic Raman and neutron scattering spectra for glasses with different degrees of fragility; the data are compared for each sample to obtain the Raman coupling function $C(ω)$. The study indicates a general linear behaviour of the $C(ω)$ near the Boson peak maximum, and evidence a correlation between vibrational and relaxational properties,

Cyril Dubus, Ken Sekimoto, Jean-Baptiste Fournier

We establish the most general form of the discrete elasticity of a 2D triangular lattice embedded in three dimensions, taking into account up to next-nearest neighbour interactions. Besides crystalline system, this is relevant to biological physics (e.g., red blood cell cytoskeleton) and soft matter (e.g., percolating gels, etc.). In order to correctly impos

Andrzej Drzewinski, J. M. J. van Leeuwen

We discuss the exact solution for the properties of the recently introduced ``necklace'' model for reptation. The solution gives the drift velocity, diffusion constant and renewal time for asymptotically long chains. Its properties are also related to a special case of the Rubinstein-Duke model in one dimension.

Ryszard Zygadło

It is shown analytically that the flashing annihilation term of a Verhulst kinetic leads to the power--law distribution in the stationary state. For the frequency of switching slower than twice the free growth rate this provides the quasideterministic source of a Levy noises at the macroscopic level.

Alvaro Corral

Spatiotemporal properties of seismicity are investigated for a worldwide (WW) catalog and for Southern California in the stationary case (SC), showing a nearly universal scaling behavior. Distributions of distances between consecutive earthquakes (jumps) are magnitude independent and show two power-law regimes, separated by jump values about 200 km (WW) and

Kaifu Luo

The morphology and dynamics of polymerization-induced phase separation in the initially homogeneous solution of a non-reactive component in reactive monomers are investigated by incorporating the reaction kinetics into the time-dependent Ginzburg Landau equation. Analytical results show that there is a reduction of the initial length scale in the early stage

Raoul Dillenschneider, Jean Richert

We study the effect of site occupation in 2d quantum spin systems at finite temperature in a $π$-flux state description at the mean-field level. We impose each lattice site to be occupied by a single SU(2) spin. This is realized by means of a specific prescription. We consider the low-energy Hamiltonian which is mapped into a $QED_3$ Lagrangian of spinons. W

Kaifu Luo, Mikko-Pekka Kuittu, Chaohui Tong, Sami Majaniemi

We study the dynamics and equilibrium profile shapes of contact lines for wetting in the case of a spatially inhomogeneous solid wall with stripe defects. Using a phase-field model with conserved dynamics, we first numerically determine the contact line behavior in the case of a stripe defect of varying width. For narrow defects, we find that the maximum dis

S. V. Kuplevakhsky, A. M. Glukhov

The problem of vortex structure in a single Josephson junction in an external magnetic field, in the absence of transport currents, is reconsidered from a new mathematical point of view. In particular, we derive a complete set of exact analytical solutions representing all the stationary points (minima and saddle-points) of the relevant Gibbs free-energy fun

Shi Xue Dou, Waikong Yeoh, Olga Shcherbakova, David Wexler

The rapid progress on MgB2 superconductor since its discovery[1] has made this material a strong competitor to low and high temperature superconductors (HTS) for applications with a great potential to catch the niche market such as in magnetic resonant imaging (MRI). Thanks to the lack of weak links and the two-gap superconductivity of MgB2 [2,3] a number of

Endre Kovacs, Zsolt Gulacsi

In the case of a two-leg Hubbard ladder we present a procedure which allows the exact deduction of the ground state for the four particle problem in arbitrary large lattice system, in a tractable manner, which involves only a reduced Hilbert space region containing the ground state. In the presented case, the method leads to nine analytic, linear, and couple

H. Seto, M. Hishida, H. Nobutou, N. L. Yamada

A swollen phase, in which the mean repeat distance of lipid bilayers is larger than the other phases, is found between the liquid-crystalline phase and the interdigitated gel phase in DPPC aqueous solution. Temperature, pressure and ethanol concentration dependences of the structure were investigated by small-angle neutron scattering, and a bending rigidity

Motohiko Ezawa

Nanoribbons (nanographite ribbons) are carbon systems analogous to carbon nanotubes. We characterize a wide class of nanoribbons by a set of two integers $<p,q>$, and then define the width $w$ in terms of $p$ and $q$. Electronic properties are explored for this class of nanoribbons. Zigzag (armchair) nanoribbons have similar electronic properties to armchair

Ching-Kit Chan, Tai-Kai Ng

The Gaussian fluctuations in slave-boson mean-field theory of $t-J$ model is analyzed in this paper in the low-doping regime where the superconducting to normal (pseudo-gap phase) transition is driven by vanishing of bose-condensation amplitude. By eliminating the boson and constraint fields exactly in the linear response regime we show that the Gaussian the

Cary Pint

This work reports an investigation into the solid phase behavior and melting behavior of tetracosane (C24H50) monolayers and bilayers physisorbed onto the graphite basal plane using molecular dynamics simulations performed in the constant (N,V,T) ensemble. This study is conducted in order to perform an in-depth analysis of the melting process in the quasi-2D

G. T. liu, J. L. Luo, Z. Li, Y. Q. Guo

A high quality superconducting Li$_{0.68}$NbO$_2$ polycrystalline sample was synthesized by deintercalation of Li ions from Li$_{0.93}$NbO$_2$. The field dependent resistivity and specific heat were measured down to 0.5 K. The upper critical field $H_{c2} (T)$ is deduced from the resistivity data and $H_{c2}(0)$ is estimated to be $\sim 2.98$ T. A notable sp

C. M. Varma

Recently, the time-reversal violation predicted for the pseudogap phase of the cuprates, which was observed by dichroism experiments using Angle-Resolved Photoemission has also been observed by polarized neutron diffraction. Earlier derivation of dichroism in angle resolved photoemission due to time-reversal violation relied on existence of mirror planes in

J. Lu, L. J. Qiao, X. Q. Ma, W. Y. Chu

Good quality and fine grain Bi6Fe2Ti3O18 magnetic ferroelectric films with single-phase layered perovskite structure have been successfully prepared via metal organic decomposition (MOD) method. Results of low-temperature magnetocapacitance measurements reveal that an ultra-low magnetic field of 10 Oe can produce a nontrivial magnetodielectric (MD) response

A. Rapisarda, A. Pluchino, C. Tsallis

In a recent letter (PRL 95, 190601 (2005)), T.M. Rocha Filho and coworkers address the very interesting issue of the entropic form to be used for Hamiltonians with long-range interactions. In our opinion the letter misses several points quite debated in the recent literature which are of fundamental importance for a complete discussion of this problem. Moreo

Nicolas Laflorencie, Stefan Wessel, Andreas Laeuchli, Heiko Rieger

The ground state properties of random-exchange spin-1/2 Heisenberg antiferromagnets on the square lattice are investigated using a combination of quantum Monte Carlo simulations, exact numerical diagonalizations, and spin wave calculations. Whereas arbirarily weak disorder has a drastic effect on 1d Heisenberg AFM, we find that in two dimensions the characte

F. E. Hudson, A. J. Ferguson, C. Yang, D. N. Jamieson

We study the low temperature electrical transport behaviour of a silicon single electron transistor. The island and leads are defined by patterned phosphorus doped regions achieved by ion implantation through a polymer resist mask. In the device a 50 nm diameter island, containing ~600 donors and having a metallic density of states, is separated from source