title:
From diluted magnetic semiconductors to self-organized nanocolumns of
  GeMn in Germanium

abstract:
  While achieving high Curie temperatures (above room temperature) in diluted
magnetic semiconductors remains a challenge in the case of well controlled
homogeneous alloys, several systems characterized by a strongly inhomogeneous
incorporation of the magnetic component appear as promising. Incorporation of
manganese into germanium drastically alters the growth conditions, and in
certain conditions of low temperature Molecular Beam Epitaxy it leads to the
formation of well organized nanocolumns of a Mn-rich material, with a
crystalline structure in epitaxial relationship with the Mn-poor germanium
matrix. A strong interaction between the Mn atoms in these nanocolums is
demonstrated by x-ray absorption spectroscopy, giving rise to a ferromagnetic
character as observed through magnetometry and x-ray magnetic circular
dichroism. Most interesting, intense magneto-transport features are observed on
the whole structure, which strongly depend on the magnetic configuration of the
nanocolumns.


title: 1-D Harmonic Oscillator in Snyder Space, the Classic and the Quantum

abstract:
  The 1-D dimension harmonic oscillator in Snyder space is investigated in its
classical and quantum versions. The classical trajectory is obtained and the
semiclassical quantization from the phase space trajectories is discussed. In
the meanwhile, an effective cutoff to high frequencies is found. The quantum
version is developed and an equivalent usual harmonic oscillator is obtained
through an effective mass and an effective frequency introduced in the model.
This modified parameters give us an also modified energy spectra.


title: Entanglement and Mixed ness of Locally Cloned Non - Maximal W - State

abstract:
  In this work we describe a protocol by which two of three parties generate
two bipartite entangled state among themselves without involving third party,
from a non maximal W state or W - type state
$|X>=\alpha|001>_{123}+\beta|010>_{123}+\gamma|100>_{123}, \alpha^{2} +
\beta^{2} + \gamma^{2} = 1$ shared by three distant partners. Also we have
considered the case $\beta=\gamma$, to obtain a range for $\alpha^2$, for which
the local output states are separable and non local output states are
inseparable. We also find out the dependence of the mixed ness of inseparable
states with their amount of inseparability, for that range of $\alpha^2$.


title:
The $\ell$-adic Dualizing Complex on an Excellent Surface with Rational
  Singularities

abstract:
  In this article, we show that if $X$ is an excellent surface with rational
singularities, the constant sheaf $\mathbb{Q}_{\ell}$ is a dualizing complex.
In coefficient $\mathbb{Z}_{\ell}$, we also prove that the obstruction for
$\mathbb{Z}_{\ell}$ to become a dualizing complex lying on the divisor class
groups at singular points. As applications, we study the perverse sheaves and
the weights of $\ell$-adic cohomology groups on such surfaces.


title:
Full-Potential Multiple Scattering Theory with Space-Filling Cells for
  bound and continuum states

abstract:
  We present a rigorous derivation of a real space Full-Potential
Multiple-Scattering-Theory (FP-MST), valid both for continuum and bound states,
that is free from the drawbacks that up to now have impaired its development,
in particular the need to use cell shape functions and rectangular matrices. In
this connection we give a new scheme to generate local basis functions for the
truncated potential cells that is simple, fast, efficient, valid for any shape
of the cell and reduces to the minimum the number of spherical harmonics in the
expansion of the scattering wave function. The method also avoids the need for
saturating 'internal sums' due to the re-expansion of the spherical Hankel
functions around another point in space (usually another cell center). Thus
this approach, provides a straightforward extension of MST in the Muffin-Tin
(MT) approximation, with only one truncation parameter given by the classical
relation $l_{\rm max} = kR_b$, where $k$ is the excited (or ground state)
electron wave vector and $R_b$ the radius of the bounding sphere of the
scattering cell. It is shown that the theory converges absolutely in the
$l_{\rm max} \to \infty$ limit. As a consequence it provides a firm ground to
the use of FP-MST as a viable method for electronic structure calculations and
makes possible the computation of x-ray spectroscopies, notably photo-electron
diffraction, absorption and anomalous scattering among others, with the ease
and versatility of the corresponding MT theory. Some numerical applications of
the theory are presented, both for continuum and bound states.


title:
Underwater Acoustic Networks: Channel Models and Network Coding based
  Lower Bound to Transmission Power for Multicast

abstract:
  The goal of this paper is two-fold. First, to establish a tractable model for
the underwater acoustic channel useful for network optimization in terms of
convexity. Second, to propose a network coding based lower bound for
transmission power in underwater acoustic networks, and compare this bound to
the performance of several network layer schemes. The underwater acoustic
channel is characterized by a path loss that depends strongly on transmission
distance and signal frequency. The exact relationship among power, transmission
band, distance and capacity for the Gaussian noise scenario is a complicated
one. We provide a closed-form approximate model for 1) transmission power and
2) optimal frequency band to use, as functions of distance and capacity. The
model is obtained through numerical evaluation of analytical results that take
into account physical models of acoustic propagation loss and ambient noise.
Network coding is applied to determine a lower bound to transmission power for
a multicast scenario, for a variety of multicast data rates and transmission
distances of interest for practical systems, exploiting physical properties of
the underwater acoustic channel. The results quantify the performance gap in
transmission power between a variety of routing and network coding schemes and
the network coding based lower bound. We illustrate results numerically for
different network scenarios.


title: Tailored photon-pair generation in optical fibers

abstract:
  We experimentally control the spectral structure of photon pairs created via
spontaneous four-wave mixing in microstructured fibers. By fabricating fibers
with designed dispersion, one can manipulate the photons' wavelengths, joint
spectrum, and, thus, entanglement. As an example, we produce photon-pairs with
no spectral correlations, allowing direct heralding of single photons in
pure-state wave packets without filtering. We achieve an experimental purity of
$85.9\pm1.6%$, while theoretical analysis and preliminary tests suggest 94.5%
purity is possible with a much longer fiber.


title:
Comment on: Nonlocal Realistic Leggett Models Can be Considered Refuted
  by the Before-Before Experiment

abstract:
  It is shown here that Suarez [Found. Phys. 38, 583 (2008)] wrongly presents
the assumptions behind the Leggett's inequalities, and their modified form used
by Groeblacher et al. [Nature 446, 871 (2007)] for an experimental
falsification of a certain class of non-local hidden variable models.


title: Languages recognized with unbounded error by quantum finite automata

abstract: This paper has been superseded by arXiv:1007.3624


title: Group algebras of finite groups as Lie algebras

abstract:
  We consider the natural Lie algebra structure on the (associative) group
algebra of a finite group $G$, and show that the Lie subalgebras associated to
natural involutive antiautomorphisms of this group algebra are reductive ones.
We give a decomposition in simple factors of these Lie algebras, in terms of
the ordinary representations of $G$.


title:
Correlation density matrix: an unbiased analysis of exact
  diagonalizations

abstract:
  Given the ground state wavefunction for an interacting lattice model, we
define a "correlation density matrix"(CDM) for two disjoint, separated clusters
$A$ and $B$, to be the density matrix of their union, minus the direct product
of their respective density matrices. The CDM can be decomposed systematically
by a numerical singular value decomposition, to provide a systematic and
unbiased way to identify the operator(s) dominating the correlations, even
unexpected ones.


title: Matrices related to Dirichlet series

abstract:
  We attach a certain $n \times n$ matrix $A_n$ to the Dirichlet series
$L(s)=\sum_{k=1}^{\infty}a_k k^{-s}$. We study the determinant, characteristic
polynomial, eigenvalues, and eigenvectors of these matrices. The determinant of
$A_n$ can be understood as a weighted sum of the first $n$ coefficients of the
Dirichlet series $L(s)^{-1}$. We give an interpretation of the partial sum of a
Dirichlet series as a product of eigenvalues. In a special case, the
determinant of $A_n$ is the sum of the M\"obius function. We disprove a
conjecture of Barrett and Jarvis regarding the eigenvalues of $A_n$.


title: On the N=2 Supersymmetric Camassa-Holm and Hunter-Saxton Equations

abstract:
  We consider N=2 supersymmetric extensions of the Camassa-Holm and
Hunter-Saxton equations. We show that they admit geometric interpretations as
Euler equations on the superconformal algebra of contact vector fields on the
1|2-dimensional supercircle. We use the bi-Hamiltonian formulation to derive
Lax pairs. Moreover, we present some simple examples of explicit solutions. As
a by-product of our analysis we obtain a description of the bounded
traveling-wave solutions for the two-component Hunter-Saxton equation.


title:
Additive invariants on quantum channels and applications to regularized
  minimum entropy

abstract:
  We introduce two additive invariants of output quantum channels. If the value
of one these invariants is less than 1 then the logarithm of the inverse of its
value is a positive lower bound for the regularized minimum entropy of an
output quantum channel. We give a few examples in which one of these invariants
is less than 1. We also study the special cases where the above both invariants
are equal to 1.


title: Depleted pyrochlore antiferromagnets

abstract:
  I consider the class of "depleted pyrochlore" lattices of corner-sharing
triangles, made by removing spins from a pyrochlore lattice such that every
tetrahedron loses exactly one. Previously known examples are the "hyperkagome"
and "kagome staircase". I give criteria in terms of loops for whether a given
depleted lattice can order analogous to the kagome \sqrt{3} \times \sqrt{three}
state, and also show how the pseudo-dipolar correlations (due to local
constraints) generalize to even the random depleted case.


title:
First observation of the decay Bs --> Ds K and measurement of the ratio
  of branching fractions Br(Bs --> DsK)/Br(Bs --> Ds pi)

abstract:
  A combined mass and particle identification fit is used to make the first
observation of the decay Bs --> Ds K and measure the branching fraction of Bs
--> Ds K relative to Bs --> Ds pi. This analysis uses 1.2 fb^-1 integrated
luminosity of pbar-p collisions at sqrt(s) = 1.96 TeV collected with the CDF II
detector at the Fermilab Tevatron collider. We observe a Bs --> Ds K signal
with a statistical significance of 8.1 sigma and measure Br(Bs --> Ds K)/Br(Bs
--> Ds pi) = 0.097 +- 0.018(stat) +- 0.009(sys).


title: Penrose Matching Rules from Realistic Potentials in a Model System

abstract:
  We exhibit a toy model of a binary decagonal Al-Co quasicrystal -- closely
related to actual structures -- in which realistic pair potentials yield a
ground state which appears to perfectly implement Penrose's matching rules, for
Hexagon-Boat-Star (HBS) tiles of edge 2.45 A. The second minimum of the
potentials is crucial for this result.


title:
A new perspective in the dark energy puzzle from particle mixing
  phenomenon

abstract:
  We report on recent results on particle mixing and oscillations in quantum
field theory. We discuss the role played in cosmology by the vacuum condensate
induced by the neutrino mixing phenomenon. We show that it can contribute to
the dark energy of the universe.


title: Discriminating MSSM families in (free-field) Gepner Orientifolds

abstract:
  A complete analysis of orientifold compactifications involving Gepner models
that are free fields (k=1,2) is performed. A set of tadpole solutions is found
that are variants of a single chiral spectrum. The vacua found have the
property that different families have different U(1) charges so that one family
cannot obtain masses in perturbation theory. Its masses must come from
instantons, allowing for a hierarchy of masses. The phenomenological aspects of
such vacua are analyzed.


title: Matching rules from Al-Co potentials in an almost realistic model

abstract:
  We consider a model decagonal quasicrystal of composition
Al$_{80.1}$Co$_{19.9}$ -- closely related to actual structures, and using
realistic pair potentials -- on a quasilattice of candidate sites. Its ground
state, according to simulations, is a Hexagon-Boat-Star tiling satisfying
Penrose's matching rules. In this note, we rationalize these results in terms
of the potentials; the Al-Co second-neighbor potential well is crucial.


title: Dark energy and particle mixing

abstract:
  We show that the vacuum condensate due to particle mixing is responsible of a
dynamically evolving dark energy. In particular, we show that values of the
adiabatic index close to -1 for vacuum condensates of neutrinos and quarks
imply, at the present epoch, contributions to the vacuum energy compatible with
the estimated upper bound on the dark energy.


title:
Twisted de Rham cohomology, homological definition of the integral and
  "Physics over a ring"

abstract:
  We define the twisted de Rham cohomology and show how to use it to define the
notion of an integral of the form $\int g(x) e^{f(x)}dx$ over an arbitrary
ring. We discuss also a definition of a family of integrals and some properties
of the homological definition of integral. We show how to use the twisted de
Rham cohomology in order to define the Frobenius map on the p-adic cohomology.
Finally, we consider two-dimensional topological quantum field theories with
general coefficients.


title: Variants of the Standard Model with Electroweak-Singlet Quarks

abstract:
  The successful description of current data provided by the Standard Model
includes fundamental fermions that are color-singlets and
electroweak-nonsinglets, but no fermions that are electroweak-singlets and
color-nonsinglets. In an effort to understand the absence of such fermions, we
construct and study {\it gedanken} models that do contain electroweak-singlet
chiral quark fields. These models exhibit several distinctive properties,
including the absence of any neutral lepton and the fact that both the $(uud)$
and $(ddu)$ nucleons are electrically charged. We also explore how such models
could arise as low-energy limits of grand unified theories and, in this more
restrictive context, we show that they exhibit further exotic properties.


title:
Generalized asymptotic Euler's relation for certain families of
  polytopes

abstract:
  According to Euler's relation any polytope P has as many faces of even
dimension as it has faces of odd dimension. As a generalization of this fact
one can compare the number of faces whose dimension is congruent to i modulo m
with the number of all faces of P for some positive integer m and for some 0 <
i < m+1. We show some classes of polytopes for which the above proportion is
asymptotically equal to 1/m.


title: Viscosity at RHIC: Theory and Practice

abstract:
  Hydrodynamic behavior and the associated discussions of viscosity at RHIC has
inspired a r enaissance in modeling viscous hydrodynamics. An explanation of
Israel-Stewart hydrodynamics is presented here, with an emphasis on the
tangible benefits compared to Navier Stokes.


title:
Chemical abundances of late-type pre-main sequence stars in the
  $\sigma$-Orionis cluster

abstract:
  The young $\sigma$-Orionis cluster is an important location for understanding
the formation and evolution of stars, brown dwarfs, and planetary-mass objects.
Its metallicity, although being a fundamental parameter, has not been well
determined yet. We present the first determination of the metallicity of nine
young late-type stars in $\sigma$-Orionis. Using the optical and near-infrared
broadband photometry available in the literature we derive the effective
temperatures for these nine cluster stars, which lie in the interval 4300--6500
K (1--3 \Msuno). These parameters are employed to compute a grid of synthetic
spectra based on the code MOOG and Kurucz model atmospheres. We employ a
$\chi^2$-minimization procedure to derive the stellar surface gravity and
atmospheric abundances of Al, Ca, Si, Fe, Ni and Li, using multi-object optical
spectroscopy taken with WYFFOS+AF2 at at the William Herschel Telescope
($\lambda/\delta\lambda\sim7500$). The average metallicity of the
$\sigma$-Orionis cluster is [Fe/H] $ = -0.02\pm0.09\pm0.13$ (random and
systematic errors). The abundances of the other elements, except lithium, seem
to be consistent with solar values. Lithium abundances are in agreement with
the "cosmic" $^7$Li abundance, except for two stars which show a $\log
\epsilon(\mathrm{Li})$ in the range 3.6--3.7 (although almost consistent within
the error bars). There are also other two stars with $\log
\epsilon(\mathrm{Li})\sim 2.75$. We derived an average radial velocity of the
$\sigma$-Orionis cluster of $28\pm4$km/s. The $\sigma$-Orionis metallicity is
roughly solar.


title: A functional view of upper bounds on codes

abstract:
  Functional and linear-algebraic approaches to the Delsarte problem of upper
bounds on codes are discussed. We show that Christoffel-Darboux kernels and
Levenshtein polynomials related to them arise as stationary points of the
moment functionals of some distributions. We also show that they can be derived
as eigenfunctions of the Jacobi operator. This motivates the choice of
polynomials used to derive linear programming upper bounds on codes in
homogeneous spaces.


title:
Pressure induced superconductivity in the charge density wave compound
  TbTe3

abstract:
  A series of high-pressure resistivity measurements on single crystals of
TbTe3 reveal a complex phase diagram involving the interplay of
superconducting, antiferromagnetic and charge density wave orders. The onset of
superconductivity reaches a maximum of ~ 3.5 K (onset) near 75 kbar.


title:
Magnetization plateaux, Haldane-like gap, string order and hidden
  symmetry in a spin-1/2 tetrameric Heisenberg antiferromagnetic chain

abstract:
  The ground-state properties of a spin $S=1/2$ tetrameric Heisenberg
antiferromagnetic chain with alternating couplings AF$_{1}$-AF$_{2}$-AF$_{1}$%
-F (AF and F denote antiferromagnetic and ferromagnetic couplings,
respectively) are studied by means of the density matrix renormalization group
method. Two plateaux of magnetization $m$ are found at $m=0$ and 1/4% . It is
shown that in such a spin-1/2 AF system, there is a gap from the singlet ground
state to the triplet excited states in the absence of a magnetic field. The
spin-spin correlation function decays exponentially, and the gapped states have
a nonvanishing string order, which measures a hidden symmetry in the system. By
a dual transformation, the string order is transformed into a ferromagnetic
order and the hidden symmetry is unveiled to be a $Z_{2}\times Z_{2}$ discrete
symmetry, which is fully broken in the gapped states. This half-integer spin
Heisenberg AF chain is in a Haldane-like phase, suggesting that the present
findings extend the substance of Haldane's scenario. A valence-bond-solid state
picture is also proposed for the gapped states.


title:
Higgs boson pair production at a photon-photon collision in the two
  Higgs doublet model

abstract:
  We calculate the cross section of Higgs boson pair production at a photon
collider in the two Higgs doublet model. We focus on the scenario in which the
lightest CP even Higgs boson ($h$) has the standard model like couplings to the
gauge bosons. We take into account the one-loop correction to the $hhh$
coupling as well as additional one-loop diagrams due to charged Higgs bosons to
the $\gamma\gamma\to hh$ helicity amplitudes. It is found that the full cross
section can be enhanced by both these effects to a considerable level. We
discuss the impact of these corrections on the $hhh$ coupling measurement at
the photon collider.


title: Dualizing complex of a toric face ring

abstract:
  A "toric face ring", which generalizes both Stanley-Reisner rings and affine
semigroup rings, is studied by Bruns, Roemer and their coauthors recently. In
this paper, under the "normality" assumption, we describe a dualizing complex
of a toric face ring $R$ in a very concise way. Since $R$ is not a graded ring
in general, the proof is not straightforward. We also develop the squarefree
module theory over $R$, and show that the Buchsbaum property and the
Gorenstein* property of $R$ are topological properties of its associated cell
complex.


title:
Rearrangement of Sodium ordering and its effect on physical properties
  in $Na_xCoO_2$ system

abstract:
  We systematically study Raman spectroscopy of cleaved Na$_x$CoO$_2$ single
crystals with 0.37 $\leq$ x $\leq$ 0.80. The Raman shift of A$_{1g}$ mode is
found to be linearly dependent on Na content, while the Raman shift of E$_{1g}$
mode has an abnormal shift to high frequency around x = 0.5. The abnormal shift
is ascribed to the occurrence of Na rearrangement in O1 structure. Temperature
dependent Raman spectrum for x = 0.56 sample shows that Na rearrangement
transition from O1 structure to H1 structure occurs around 240 K. Electronic
transport and susceptibility for the sample with $x=0.56$ show a response to
the Na rearrangement transition from O1 to H1 structure, and that different Na
ordering pattern causes distinct physical properties. These results give a
direct evidence to proved Na ordering effect on physical properties of Co-O
plane.


title: The Hamiltonian formulation of General Relativity: myths and reality

abstract:
  A conventional wisdom often perpetuated in the literature states that: (i) a
3+1 decomposition of space-time into space and time is synonymous with the
canonical treatment and this decomposition is essential for any Hamiltonian
formulation of General Relativity (GR); (ii) the canonical treatment
unavoidably breaks the symmetry between space and time in GR and the resulting
algebra of constraints is not the algebra of four-dimensional diffeomorphism;
(iii) according to some authors this algebra allows one to derive only spatial
diffeomorphism or, according to others, a specific field-dependent and
non-covariant four-dimensional diffeomorphism; (iv) the analyses of Dirac
[Proc. Roy. Soc. A 246 (1958) 333] and of ADM [Arnowitt, Deser and Misner, in
"Gravitation: An Introduction to Current Research" (1962) 227] of the canonical
structure of GR are equivalent. We provide some general reasons why these
statements should be questioned. Points (i-iii) have been shown to be incorrect
in [Kiriushcheva et al., Phys. Lett. A 372 (2008) 5101] and now we thoroughly
re-examine all steps of the Dirac Hamiltonian formulation of GR. We show that
points (i-iii) above cannot be attributed to the Dirac Hamiltonian formulation
of GR. We also demonstrate that ADM and Dirac formulations are related by a
transformation of phase-space variables from the metric $g_{\mu\nu}$ to lapse
and shift functions and the three-metric $g_{km}$, which is not canonical. This
proves that point (iv) is incorrect. Points (i-iii) are mere consequences of
using a non-canonical change of variables and are not an intrinsic property of
either the Hamilton-Dirac approach to constrained systems or Einstein's theory
itself.


title: Twisting of the Quantum double and the Weyl algebra

abstract:
  Quantum double construction, originally due to Drinfeld and has been since
generalized even to the operator algebra framework, is naturally associated
with a certain (quasitriangular) $R$-matrix ${\mathcal R}$. It turns out that
${\mathcal R}$ determines a twisting of the comultiplication on the quantum
double. It then suggests a twisting of the algebra structure on the dual of the
quantum double. For $D(G)$, the $C^*$-algebraic quantum double of an ordinary
group $G$, the "twisted $\hat{D(G)}$" turns out to be the Weyl algebra
$C_0(G)\times_{\tau}G$, which is in turn isomorphic to ${\mathcal K}(L^2(G))$.
This is the $C^*$-algebraic counterpart to an earlier (finite-dimensional)
result by Lu. It is not so easy technically to extend this program to the
general locally compact quantum group case, but we propose here some possible
approaches, using the notion of the (generalized) Fourier transform.


title:
Degrees of Freedom of the $K$ User $M \times N$ MIMO Interference
  Channel

abstract:
  We provide innerbound and outerbound for the total number of degrees of
freedom of the $K$ user multiple input multiple output (MIMO) Gaussian
interference channel with $M$ antennas at each transmitter and $N$ antennas at
each receiver if the channel coefficients are time-varying and drawn from a
continuous distribution. The bounds are tight when the ratio
$\frac{\max(M,N)}{\min(M,N)}=R$ is equal to an integer. For this case, we show
that the total number of degrees of freedom is equal to $\min(M,N)K$ if $K \leq
R$ and $\min(M,N)\frac{R}{R+1}K$ if $K > R$. Achievability is based on
interference alignment. We also provide examples where using interference
alignment combined with zero forcing can achieve more degrees of freedom than
merely zero forcing for some MIMO interference channels with constant channel
coefficients.


title:
Searching Higgs in Noncommutative Electroweak Model at Photon-Photon
  Collider

abstract:
  We discuss the process of Higgs boson production in $\gamma\gamma$ collider
on noncommutative spacetime and compare the results with large extra dimension
in KK graviton channel. Summing all KK mode on IR brane, the affections are in
the same order by comparing noncommutatve model prediction. This process is
completely forbidden in standard model on unitarity condition and bosonic
distribution. In noncommutative theory, the effect is induced by the
coordinates noncommutable relation, $[x^{\mu}, x^{\nu}]$ = $i\theta^{\mu\nu}$.
Due to the constant background strength tensor does not contain any conserved
quantum number, hence, this effort is indicated into particle power spectrum.
Particle mass spectrum is corrected by radiational and anisotropic
surroundings. The process of $\gamma\gamma\to H^{0}H^{0}$ restricts the
unitarity condition in noncommutative field theory. Under power law
conservation condition, the neutral Higgs mass below gauge boson resonance will
produce a accelerated phenomena as the central energy is higher than $Z_{0}$
gauge boson creation scale. The effects generated from the vast light Higgs
particles descend the power rate energy distribution as far as the ambient is
under a balance. The fractional rate on polarized polars are very small
embedded into the unpolarized surroundings depend on background electric field
couplings.


title:
Evidence of dispersion relations for the nonlinear response of the
  Lorenz 63 system

abstract:
  Along the lines of the nonlinear response theory developed by Ruelle, in a
previous paper we have proved under rather general conditions that
Kramers-Kronig dispersion relations and sum rules apply for a class of
susceptibilities describing at any order of perturbation the response of Axiom
A non equilibrium steady state systems to weak monochromatic forcings. We
present here the first evidence of the validity of these integral relations for
the linear and the second harmonic response for the perturbed Lorenz 63 system,
by showing that numerical simulations agree up to high degree of accuracy with
the theoretical predictions. Some new theoretical results, showing how to
obtain recursively harmonic generation susceptibilities for general
observables, are also presented. Our findings confirm the conceptual validity
of the nonlinear response theory, suggest that the theory can be extended for
more general non equilibrium steady state systems, and shed new light on the
applicability of very general tools, based only upon the principle of
causality, for diagnosing the behavior of perturbed chaotic systems and
reconstructing their output signals, in situations where the
fluctuation-dissipation relation is not of great help.

categories: cond-mat.stat-mech cond-mat.other math-ph math.DS math.MP nlin.CD physics.flu-dyn


title: Maxwell electromagnetic theory from a viewpoint of differential forms

abstract:
  In this paper, we discuss the Maxwell equations in terms of differential
forms, both in the 3-dimensional space and in the 4-dimensional space-time
manifold. Further, we view the classical electrodynamics as the curvature of a
line bundle, and fit it into gauge theory.


title: On the nature of long-range letter correlations in texts

abstract:
  The origin of long-range letter correlations in natural texts is studied
using random walk analysis and Jensen-Shannon divergence. It is concluded that
they result from slow variations in letter frequency distribution, which are a
consequence of slow variations in lexical composition within the text. These
correlations are preserved by random letter shuffling within a moving window.
As such, they do reflect structural properties of the text, but in a very
indirect manner.


title:
Some families of supersingular Artin-Schreier curves in characteristic >
  2

abstract:
  In this short paper we prove that the following two 1-dimensional families of
Artin-Schreier curves are supersingular: y^7 - y = x^5 + c.x^2 over F_7 y^5 - y
= x^7 + c.x over F_5 (for some parameter c). Our method is developed upon the
p-adic Dwork's method.


title: Finite Sets and Counting

abstract:
  We start by presenting a theory of finite sets using the approach which is
essentially that taken by Whitehead and Russell in Principia Mathematica}, and
which does not involve the natural numbers (or any other infinite set). This
theory is then applied to prove results about structures which, like the
natural numbers, satisfy the principle of mathematical induction, but do not
necessarily satisfy the remaining Peano axioms.


title: Overlap Interfaces in Hierarchical Spin-Glass models

abstract:
  We discuss interfaces in spin glasses. We present new theoretical results and
a numerical method to characterize overlap interfaces and the stability of the
spin-glass phase in extended disordered systems. We use this definition to
characterize the low temperature phase of hierarchical spin-glass models. We
use the Replica Symmetry Breaking theory to evaluate the cost for an overlap
interface, which in these models is particularly simple. A comparison of our
results from numerical simulations with the theoretical predictions shows good
agreement.


title:
Local-Ansatz Approach with Momentum Dependent Variational Parameters to
  Correlated Electron Systems

abstract:
  A new wavefunction which improves the Gutzwiller-type local ansatz method has
been proposed to describe the correlated electron system. The ground-state
energy, double occupation number, momentum distribution function, and
quasiparticle weight have been calculated for the half-filled band Hubbard
model in infinite dimensions. It is shown that the new wavefunction improves
the local-ansatz approach (LA) proposed by Stollhoff and Fulde. Especially,
calculated momentum distribution functions show a reasonable momentum
dependence. The result qualitatively differs from those obtained by the LA and
the Gutzwiller wavefunction. Furthermore, the present approach combined with
the projection operator method CPA is shown to describe quantitatively the
excitation spectra in the insulator regime as well as the critical Coulomb
interactions for a gap formation in infinite dimensions.


title: Bodies of zero resistance and bodies invisible in one direction

abstract:
  We consider a body in a parallel flow of non-interacting particles. The
interaction of particles with the body is perfectly elastic. We introduce the
notions of a body of zero resistance, a body that leaves no trace, and an
invisible body, and prove that all such bodies do exist.


title: X-ray Halo Around the Spiral Galaxy NGC 4631 Observed with Suzaku

abstract:
  Suzaku observation of the edge-on spiral galaxy NGC 4631 confirmed its X-ray
halo extending out to about 10 kpc from the galactic disk. The XIS spectra
yielded the temperature and metal abundance for the disk and the halo regions.
The observed abundance pattern for O, Ne, Mg, Si and Fe is consistent with the
metal yield from type II supernovae, with an O mass of about 1E6 Msun contained
in the halo. These features imply that metal-rich gas produced by type II
supernova is brought into the halo region very effectively, most likely through
a galactic wind. Temperature and metal abundance may be affected by charge
exchange and dust. An upper limit for the hard X-ray flux was obtained,
corresponding to a magnetic field higher than 0.5 uG.


title: On Nakhleh's latest metric for phylogenetic networks

abstract:
  We prove that Nakhleh's latest dissimilarity measure for phylogenetic
networks is a metric on the classes of tree-child phylogenetic networks, of
semi-binary time consistent tree-sibling phylogenetic networks, and of
multi-labeled phylogenetic trees. We also prove that it distinguishes
phylogenetic networks with different reduced versions. In this way, it becomes
the dissimilarity measure for phylogenetic networks with the strongest
separation power available so far.


title: Standard Model scales from warped extra dimensions

abstract:
  If in the Randall and Sundrum RS1 model the inverse of the compactification
radius, the AdS curvature scale, and the five and four-dimensional Planck
scales are equal in size, as is natural, then the warp factor at the location
of the low energy brane is of value 1/pi. So that all scales derive from
locations in the space, we identify the extra dimension with the infinite
covering space of the S1/Z2 orbifold. The extra dimension is then essentially a
series of connected line intervals, punctuated by branes. Scales on successive
branes in the extra dimension descend from Planck scale in a geometric sequence
of common ratio 1/pi. Evidence is provided for such a sequence within the
spectrum of particle masses, and of a second geometric sequence, of common
ratio 2/pi, which suggests that the AdS spacetime is six-dimensional and doubly
warped. The scales of the Standard Model lie at coincident levels within the
two sequences. A third sequence, of common ratio 1/e, provides a symmetrical
framework for the Standard Model and points to a warped product spacetime.


title: Decay of turbulence generated by spin-down to rest in superfluid 4He

abstract:
  We report on the extension of the experiments (P. M. Walmsley et al., Phys.
Rev. Lett. 99, 265302 (2007)) on the decay of quasiclassical turbulence
generated by an impulsive spin-down from angular velocity Omega to rest of
superfluid 4He in a cubic container at temperatures 0.15 K - 1.6 K. The density
of quantized vortex lines L is measured by scattering negative ions. Following
the spin-down, the maximal density of vortices is observed after time t ~ 10
Omega^-1. By observing the propagation of ions along the axis of the initial
rotation, the transient dynamics of the turbulence spreading from the perimeter
of the container into its central region is investigated. Nearly homogeneous
turbulence develops after time t ~ 100 Omega^-1 and decays as L proportional to
t^(-3/2). The effective kinematic viscosity in T=0 limit is nu = 0.003 kappa,
where kappa=10^-3 cm^2 / s is the circulation quantum.


title: Solitons in one-dimensional photonic crystals

abstract:
  We report results of a systematic analysis of spatial solitons in the model
of 1D photonic crystals, built as a periodic lattice of waveguiding channels,
of width D, separated by empty channels of width L-D. The system is
characterized by its structural "duty cycle", DC = D/L. In the case of the
self-defocusing (SDF) intrinsic nonlinearity in the channels, one can predict
new effects caused by competition between the linear trapping potential and the
effective nonlinear repulsive one. Several species of solitons are found in the
first two finite bandgaps of the SDF model, as well as a family of fundamental
solitons in the semi-infinite gap of the system with the self-focusing
nonlinearity. At moderate values of DC (such as 0.50), both fundamental and
higher-order solitons populating the second bandgap of the SDF model suffer
destabilization with the increase of the total power. Passing the
destabilization point, the solitons assume a flat-top shape, while the shape of
unstable solitons gets inverted, with local maxima appearing in empty layers.
In the model with narrow channels (around DC =0.25), fundamental and
higher-order solitons exist only in the first finite bandgap, where they are
stable, despite the fact that they also feature the inverted shape.


title: Quintom model with O($N$) symmetry

abstract:
  We investigate the quintom model of dark energy in the generalized case where
the corresponding canonical and phantom fields possess O($N$) symmetries.
Assuming exponential potentials we find that this O$(N)$ quintom paradigm
exhibits novel properties comparing to the simple canonical and phantom
scenarios. In particular, we find that the universe cannot result in a
quintessence-type solution with $w>-1$, even in the cases where the phantom
field seems to be irrelevant. On the contrary, there are always late-time
attractors which correspond to accelerating universes with $w<-1$ and with a
recent crossing of the phantom divide, and for a very large area of the
parameter space they are the only ones. This is in contrast with the previous
simple-quintom results, where an accelerating universe is a possible late-time
stable solution but it is not guaranteed.


title: Unexpected reemergence of von Neumann theorem

abstract:
  Is is shown here that the "simple test of quantumness for a single system" of
arXiv:0704.1962 (for a recent experimental realization see arXiv:0804.1646) has
exactly the same relation to the discussion of to the problem of describing the
quantum system via a classical probabilistic scheme (that is in terms of hidden
variables, or within a realistic theory) as the von Neumann theorem (1932). The
latter one was shown by Bell (1966) to stem from an assumption that the hidden
variable values for a sum of two non-commuting observables (which is an
observable too) have to be, for each individual system, equal to sums of
eigenvalues of the two operators. One cannot find a physical justification for
such an assumption to hold for non-commeasurable variables. On the positive
side. the criterion may be useful in rejecting models which are based on
stochastic classical fields. Nevertheless the example used by the Authors has a
classical optical realization.


title: Toward Expressive and Scalable Sponsored Search Auctions

abstract:
  Internet search results are a growing and highly profitable advertising
platform. Search providers auction advertising slots to advertisers on their
search result pages. Due to the high volume of searches and the users' low
tolerance for search result latency, it is imperative to resolve these auctions
fast. Current approaches restrict the expressiveness of bids in order to
achieve fast winner determination, which is the problem of allocating slots to
advertisers so as to maximize the expected revenue given the advertisers' bids.
The goal of our work is to permit more expressive bidding, thus allowing
advertisers to achieve complex advertising goals, while still providing fast
and scalable techniques for winner determination.


title:
On the noncommutative Donaldson-Thomas invariants arising from brane
  tilings

abstract:
  Given a brane tiling, that is a bipartite graph on a torus, we can associate
with it a quiver potential and a quiver potential algebra. Under certain
consistency conditions on a brane tiling, we prove a formula for the
Donaldson-Thomas type invariants of the moduli space of framed cyclic modules
over the corresponding quiver potential algebra. We relate this formula with
the counting of perfect matchings of the periodic plane tiling corresponding to
the brane tiling. We prove that the same consistency conditions imply that the
quiver potential algebra is a 3-Calabi-Yau algebra. We also formulate a
rationality conjecture for the generating functions of the Donaldson-Thomas
type invariants.


title: A New Description of Cosmic Strings in Brane World Scenario

abstract:
  In the light of $\phi$-mapping topological current theory, the structure of
cosmic strings are obtained from the Abelian Higgs model, which is an effective
description to the brane world cosmic string system. In this topological
description of the cosmic string, combining the result of decomposition of U(1)
gauge potential, we analytically reach the familiar conclusions that in the
brane world scenario the magnetic flux of the cosmic string is quantized and
the RR charge of it is screened.


title: Nonsmoothable group actions on spin 4-manifolds

abstract:
  We show that every closed, simply connected, spin topological 4-manifold
except $S^4$ and $S^2\times S^2$ admits a homologically trivial, pseudofree,
locally linear action of $\mathbb{Z}_p$ for any sufficiently large prime number
$p$ which is nonsmoothable for any possible smooth structure.


title: Magnetic Monopoles in Ferromagnetic Spin-Triplet Superconductors

abstract:
  Using the $\phi$-mapping method, we argue that ferromagnetic spin-triplet
superconductors allow formation of unstable magnetic monopoles. In particular,
we show that the limit points and the bifurcation points of the $\phi$-mapping
will serve as the interaction points of these magnetic monopoles.


title:
On the distribution of linear combinations of eigenvalues of the
  Anderson model

abstract:
  Probabilistic estimates on linear combinations of eigenvalues of the one
dimensional Anderson model are derived. So far only estimates on the density of
eigenvalues and of pairs were found by Wegner and by Minami. Our work was
motivated by perturbative explorations of the Nonlinear Schroedinger Equation,
where linear combinations of eigenvalues are the denominators and evaluation of
their smallness is crucial.


title: Recent Developments in Heavy-Quarkonium Phenomenology

abstract:
  We review recent developments in heavy-quarkonium phenomenology within the
nonrelativistic QCD factorization approach. Main issues we consider in this
work include the polarization of prompt J/psi at the Fermilab Tevatron and the
large relativistic and QCD corrections to double-charmonium production at the B
factories. We also consider inclusive charm production in bottomonia decays.


title:
Modified London Equation, Abrikosov-Like Vortices and Knot Solitons in
  Two-Gap Superconductors

abstract:
  We derive the exact modified London equation for the two-gap superconductor,
compare it with its single-gap counterpart. We show that the vortices in the
two-gap superconductor are soft (or continuous) core vortices. In particular,
we discuss the topological structure of the finite energy vortices
(Abrikosov-like vortices), and find that they can be viewed as the incarnation
of the baby skyrmion stretched in the third direction. Besides, we point out
that the knot soliton in the two-gap superconductor is the twisted
Abrikosov-like vortex with its two periodic ends connected smoothly. The
relation between the magnetic monopoles and the Abrikosov-like vortices is also
discussed briefly.


title: A Uniform Approach to Analogies, Synonyms, Antonyms, and Associations

abstract:
  Recognizing analogies, synonyms, antonyms, and associations appear to be four
distinct tasks, requiring distinct NLP algorithms. In the past, the four tasks
have been treated independently, using a wide variety of algorithms. These four
semantic classes, however, are a tiny sample of the full range of semantic
phenomena, and we cannot afford to create ad hoc algorithms for each semantic
phenomenon; we need to seek a unified approach. We propose to subsume a broad
range of phenomena under analogies. To limit the scope of this paper, we
restrict our attention to the subsumption of synonyms, antonyms, and
associations. We introduce a supervised corpus-based machine learning algorithm
for classifying analogous word pairs, and we show that it can solve
multiple-choice SAT analogy questions, TOEFL synonym questions, ESL
synonym-antonym questions, and similar-associated-both questions from cognitive
psychology.


title:
What Hubble really meant by late and early type: simply more or less
  complex in appearance

abstract:
  It is widely written and believed that Edwin Hubble introduced the terms
`early' and `late types' to suggest an evolutionary sequence for galaxies. This
is incorrect. Hubble took these terms from spectral classification of stars to
signify a sequence related to complexity of appearance, albeit based on images
rather than spectra. The temporal connotations of the terms had been abandoned
prior to his 1926 paper on classification of galaxies.


title: Coordinate transformations in quaternion spaces

abstract:
  The quaternion spaces can be used to describe the property of electromagnetic
field and gravitational field. In the quaternion space, some coordinate
transformations can be deduced from the feature of quaternions, including
Lorentz transformation and Galilean transformation etc., when the coordinate
system is transformed into others. And some coordinate transformations with
variable speed of light can be obtained in the electromagnetic field and
gravitational field.


title: The Reverse Ultra Log-Concavity of the Boros-Moll Polynomials

abstract:
  We prove the reverse ultra log-concavity of the Boros-Moll polynomials. We
further establish an inequality which implies the log-concavity of the sequence
$\{i!d_i(m)\}$ for any $m\geq 2$, where $d_i(m)$ are the coefficients of the
Boros-Moll polynomials $P_m(a)$. This inequality also leads to the fact that in
the asymptotic sense, the Boros-Moll sequences are just on the borderline
between ultra log-concavity and reverse ultra log-concavity. We propose two
conjectures on the log-concavity and reverse ultra log-concavity of the
sequence $\{d_{i-1}(m) d_{i+1}(m)/d_i(m)^2\}$ for $m\geq 2$.


title: Pressure effect on superconductivity and magnetism in FeSex

abstract:
  In this paper, pressure effect on superconductivity and magnetism has been
investigated in FeSex (x = 0.80, 0.88). The magnetization curves display
anomaly at Ts1 106 K and Ts2 78 K except for the superconducting diamagnetic
transition around Tc 8 K. The magnetic anomaly at Ts1 and Ts2 can be related to
a ferromagnetic and an antiferromagnetic phase transition, respectively, as
revealed by specific heat measurements. The application of pressure not only
raises Tc, but also increases both Ts1 and Ts2. This system shows clear
evidence that superconductivity arises in a phase with strong magnetic
character and the superconductivity coexists with magnetism. In addition, the
specific heat anomaly associated with the superconducting transition seems to
be absent.


title:
The transition to irreversibility in sheared suspensions: An analysis
  based on a mesoscopic entropy production

abstract:
  We study the shear-induced diffusion effect and the transition to
irreversibility in suspensions under oscillatory shear flow by performing an
analysis of the entropy production associated to the motion of the particles.
We show that the Onsager coupling between different contributions to the
entropy production is responsible for the scaling of the mean square
displacement on particle diameter and applied strain. We also show that the
shear-induced effective diffusion coefficient depends on the volume fraction
and use Lattice-Boltzmann simulations to characterize the effect through the
power spectrum of particle positions for different Reynolds numbers and volume
fractions. Our study gives a thermodynamic explanation of the the transition to
irreversibility through a pertinent analysis of the second law of
thermodynamics.


title:
Heavy-to-light transition form factors and their relations in light-cone
  QCD sum rules

abstract:
  The improved light-cone QCD sum rules by using chiral current correlator is
systematically reviewed and applied to the calculation of all the
heavy-to-light form factors, including all the semileptonic and penguin ones.
By choosing suitable chiral currents, the light-cone sum rules for all the form
factors are greatly simplified and depend mainly on one leading twist
distribution amplitude of the light meson. As a result, relations between these
form factors arise naturally. At the considered accuracy these relations
reproduce the results obtained in the literature. Moreover, since the explicit
dependence on the leading twist distribution amplitudes is preserved, these
relations may be more useful to simulate the experimental data and extract the
information on the distribution amplitude.


title: Representation zeta functions of wreath products with finite groups

abstract:
  Let G be a group which has for all n a finite number r_n(G) of irreducible
complex linear representations of dimension n. Let $\zeta(G,s) =
\sum_{n=1}^{\infty} r_n(G) n^{-s}$ be its representation zeta function.
  First, in case G is a permutational wreath product of H with a permutation
group Q acting on a finite set X, we establish a formula for $\zeta(G,s)$ in
terms of the zeta functions of H and of subgroups of Q, and of the Moebius
function associated with the lattice of partitions of X in orbits under
subgroups of Q.
  Then, we consider groups W(Q,k) which are k-fold iterated wreath products of
Q, and several related infinite groups W(Q), including the profinite group, a
locally finite group, and several finitely generated groups, which are all
isomorphic to a wreath product of themselves with Q. Under convenient
hypotheses (in particular Q should be perfect), we show that r_n(W(Q)) is
finite for all n, and we establish that the Dirichlet series $\zeta(W(Q),s)$
has a finite and positive abscissa of convergence s_0.
  Moreover, the function $\zeta(W(Q),s)$ satisfies a remarkable functional
equation involving $\zeta(W(Q),es)$ for e=1,...,|X|. As a consequence of this,
we exhibit some properties of the function, in particular that $\zeta(W(Q),s)$
has a singularity at s_0, a finite value at s_0, and a Puiseux expansion around
s_0.
  We finally report some numerical computations for Q the simple groups of
order 60 and 168.


title: Preparation of ODA-clay hybrid films by Langmuir-Blodgett technique

abstract:
  Hybrid monolayers of clay minerals (hectorite) and Octadecyamine (ODA) were
prepared using the Langmuir-Blodgett (LB) technique. Surface pressure-area per
molecule isotherm, FTIR and atomic force microscopy were used to confirm and
analyze the ODA-hectorite hybrid films. The monolayer thickness is 2 nm and
average height, length and width of individual clay platelets ranges between
1.5 to 2 nm, 500 to 1250 nm and 100 to 115 nm respectively. The surface
coverage was more than 80%.


title: Soliton-based discriminator of non-coherent optical pulses

abstract:
  We introduce a concept of noncoherent optical pulse discrimination from a
coherent (or partially coherent) signal of the same energy using a phenomenon
of soliton generation. The impact of randomisation of the optical signal
content on the observable characteristics of solitons generation is examined
and quantified for a particular example of rectangular pulse.


title: Hodge polynomials of some moduli spaces of Coherent Systems

abstract:
  When $k<n$, we study the coherent systems that come from a BGN extension in
which the quotient bundle is strictly semistable. In this case we describe a
stratification of the moduli space of coherent systems. We also describe the
strata as complements of determinantal varieties and we prove that these are
irreducible and smooth. These descriptions allow us to compute the Hodge
polynomials of this moduli space in some cases. In particular, we give explicit
computations for the cases in which $(n,d,k)=(3,d,1)$ and $d$ is even,
obtaining from them the usual Poincar\'e polynomials.


title:
On Hamiltonian potentials with quartic polynomial normal variational
  equations

abstract:
  In this paper we prove that there exists only one family of classical
Hamiltonian systems of two degrees of freedom with invariant plane
$\Gamma=\{q_2=p_2=0\}$ whose normal variational equation around integral curves
in $\Gamma$ is generically a Hill-Schr\"odinger equation with quartic
polynomial potential. In particular, by means of the Morales-Ramis theory,
these Hamiltonian systems are non-integrable through rational first integrals.


title: Effective Temperature in a Colloidal Glass

abstract:
  We study the Brownian motion of particles trapped by optical tweezers inside
a colloidal glass (Laponite) during the sol-gel transition. We use two methods
based on passive rheology to extract the effective temperature from the
fluctuations of the Brownian particles. All of them give a temperature that,
within experimental errors, is equal to the heat bath temperature. Several
interesting features concerning the statistical properties and the long time
correlations of the particles are observed during the transition.


title:
High-Dimensional Menger-Type Curvatures-Part II: d-Separation and a
  Menagerie of Curvatures

abstract:
  This is the second of two papers wherein we estimate multiscale least squares
approximations of certain measures by Menger-type curvatures. More
specifically, we study an arbitrary d-regular measure on a real separable
Hilbert space. The main result of the paper bounds the least squares error of
approximation at any ball by an average of the discrete Menger-type curvature
over certain simplices in in the ball. A consequent result bounds the
Jones-type flatness by an integral of the discrete curvature over all
simplices. The preceding paper provided the opposite inequalities. Furthermore,
we demonstrate some other discrete curvatures for characterizing uniform
rectifiability and additional continuous curvatures for characterizing special
instances of the (p, q)-geometric property. We also show that a curvature
suggested by Leger (Annals of Math, 149(3), p. 831-869, 1999) does not fit
within our framework.


title:
Imaging Observations of Quasi-Periodic Pulsatory Non-Thermal Emission in
  Ribbon Solar Flares

abstract:
  Using RHESSI and some auxiliary observations we examine possible connections
between spatial and temporal morphology of the sources of non-thermal hard
X-ray (HXR) emission which revealed minute quasi-periodic pulsations (QPPs)
during the two-ribbon flares on 2003 May 29 and 2005 January 19. Microwave
emission also reveals the same quasi-periodicity. The sources of non-thermal
HXR emission are situated mainly inside the footpoints of the flare arcade
loops observed by the TRACE and SOHO instruments. At least one of the sources
moves systematically both during the QPP-phase and after it in each flare that
allows to examine the sources velocities and the energy release rate via the
process of magnetic reconnection. The sources move predominantly parallel to
the magnetic inversion line or the appropriate flare ribbon during the
QPP-phase whereas the movement slightly changes to more perpendicular regime
after the QPPs. Each QPP is emitted from its own position. It is also seen that
the velocity and the energy release rate don't correlate well with the flux of
the HXR emission calculated from the sources. The sources of microwaves and
thermal HXRs are situated near the apex of the loop arcade and are not
stationary either. Almost all QPPs and some spikes of HXR emission during the
post-QPP-phase reveal the soft-hard-soft spectral behavior indicating separate
acts of electrons acceleration and injection, rather than modulation of
emission flux by some kinds of magnetohydrodynamic (MHD) oscillations of
coronal loops. In all likelihood, the flare scenarios based on the successively
firing arcade loops are more preferable to interpret the observations, although
we can not conclude exactly what mechanism forces these loops to flare up.


title: Critical Behavior of Ferromagnetic Ising Model on Triangular Lattice

abstract:
  We apply a new updating algorithm scheme to investigate the critical behavior
of the two-dimensional ferromagnetic Ising model on a triangular lattice with
nearest neighbour interactions. The transition is examined by generating
accurate data for large lattices with $L=8,10,12,15,20,25,30,40,50$. The spin
updating algorithm we employ has the advantages of both metropolis and
single-update methods. Our study indicates that the transition to be continuous
at $T_c=3.6403(2)$. A convincing finite-size scaling analysis of the model
yield $\nu=0.9995(21)$, $\beta/\nu=0.12400(18)$, $\gamma/\nu=1.75223(22)$,
$\gamma'/\nu=1.7555(22)$, $\alpha/\nu=0.00077(420)$ (scaling) and
$\alpha/\nu=0.0010(42)$(hyperscaling) respectively. Estimates of present scheme
yield accurate estimates for all critical exponents than those obtained with
Monte Carlo methods and show an excellent agreement with their well-established
predicted values.


title: The Weinstein conjecture for stable Hamiltonian structures

abstract:
  We use the equivalence between embedded contact homology and Seiberg-Witten
Floer homology to obtain the following improvements on the Weinstein
conjecture. Let Y be a closed oriented connected 3-manifold with a stable
Hamiltonian structure, and let R denote the associated Reeb vector field on Y.
We prove that if Y is not a T^2-bundle over S^1, then R has a closed orbit.
Along the way we prove that if Y is a closed oriented connected 3-manifold with
a contact form such that all Reeb orbits are nondegenerate and elliptic, then Y
is a lens space. Related arguments show that if Y is a closed oriented
3-manifold with a contact form such that all Reeb orbits are nondegenerate, and
if Y is not a lens space, then there exist at least three distinct embedded
Reeb orbits.


title: The t-stability number of a random graph

abstract:
  Given a graph G = (V,E), a vertex subset S is called t-stable (or
t-dependent) if the subgraph G[S] induced on S has maximum degree at most t.
The t-stability number of G is the maximum order of a t-stable set in G. We
investigate the typical values that this parameter takes on a random graph on n
vertices and edge probability equal to p. For any fixed 0 < p < 1 and fixed
non-negative integer t, we show that, with probability tending to 1 as n grows,
the t-stability number takes on at most two values which we identify as
functions of t, p and n. The main tool we use is an asymptotic expression for
the expected number of t-stable sets of order k. We derive this expression by
performing a precise count of the number of graphs on k vertices that have
maximum degree at most k. Using the above results, we also obtain asymptotic
bounds on the t-improper chromatic number of a random graph (this is the
generalisation of the chromatic number, where we partition of the vertex set of
the graph into t-stable sets).


title: Quantum chaos and its kinetic stage of evolution

abstract:
  Usually reason of irreversibility in open quantum-mechanical system is
interaction with a thermal bath, consisting form infinite number of degrees of
freedom. Irreversibility in the system appears due to the averaging over all
possible realizations of the environment states. But, in case of open
quantum-mechanical system with few degrees of freedom situation is much more
complicated. Should one still expect irreversibility, if external perturbation
is just an adiabatic force without any random features? Problem is not clear
yet. This is main question we address in this review paper. We prove that key
point in the formation of irreversibility in chaotic quantum-mechanical systems
with few degrees of freedom, is the complicated structure of energy spectrum.
We shall consider quantum mechanical-system with parametrically dependent
energy spectrum. In particular, we study energy spectrum of the
Mathieu-Schrodinger equation. Structure of the spectrum is quite non-trivial,
consists from the domains of non-degenerated and degenerated stats, separated
from each other by branch points.


title: The Adjoint L-function of SU(2,1)

abstract:
  We modify Ginzburg's construction for the Adjoint L function of GL(3)
(unfolding and unramified computations only) to accomodate quasisplit unitary
groups.


title: A differential U-module algebra for U=U_q sl(2) at an even root of unity

abstract:
  We show that the full matrix algebra Mat_p(C) is a U-module algebra for U =
U_q sl(2), a 2p^3-dimensional quantum sl(2) group at the 2p-th root of unity.
Mat_p(C) decomposes into a direct sum of projective U-modules P^+_n with all
odd n, 1<=n<=p. In terms of generators and relations, this U-module algebra is
described as the algebra of q-differential operators "in one variable" with the
relations D z = q - q^{-1} + q^{-2} z D and z^p = D^p = 0. These relations
define a "parafermionic" statistics that generalizes the fermionic commutation
relations. By the Kazhdan--Lusztig duality, it is to be realized in a
manifestly quantum-group-symmetric description of (p,1) logarithmic conformal
field models. We extend the Kazhdan--Lusztig duality between U and the (p,1)
logarithmic models by constructing a quantum de Rham complex of the new
U-module algebra.


title:
Two pressure-induced transitions in TiOCl: Mott insulator to anisotropic
  metal

abstract:
  Using Car-Parrinello molecular dynamics calculations we investigate the
behavior of the low-dimensional multiorbital Mott insulator TiOCl under
pressure. We show that the system undergoes {\it two} consecutive phase
transitions, first at $P_\text{c}$ from a Mott-insulator to a metallic phase in
the $ab$ plane with a strong Ti-Ti dimerization along $b$. At a pressure
$P'_\text{c} > P_\text{c}$ the dimerization disappears and the system behaves
as a uniform metal. This second transition has not yet been reported
experimentally. We show that the insulator-to-metal transition at $P_\text{c}$
is driven by the widening of the bandwidth rather than structural changes or
reduction of crystal field splittings and it shows a redistribution of the
electronic occupation within the $t_{2g}$ bands. Our computed
pressure-dependent lattice parameters are consistent with experimental
observations and the existing controversy on the change of crystal symmetry at
high pressures is discussed.


title:
Rotational molecular dynamics of laser-manipulated bromotrifluoromethane
  studied by x-ray absorption

abstract:
  We present a computational study of the rotational molecular dynamics of
bromotrifluoromethane (CF3Br) molecules in gas phase. The rotation is
manipulated with an offresonant, 800nm laser. The molecules are treated as
rigid rotors. Frequently, we use a computationally efficient linear rotor model
for CF3Br which we compare with selected results for full symmetric-rotor
computations. The expectation value <cos^2 theta>(t) is discussed. Especially,
the transition from impulsive to adiabatic alignment, the temperature
dependence of the maximally achievable alignment and its intensity dependence
are investigated. In a next step, we examine resonant x-ray absorption as an
accurate tool to study laser manipulation of molecular rotation. Specifically,
we investigate the impact of the x-ray pulse duration on the signal
(particularly its temporal resolution), and study the temperature dependence of
the achievable absorption. Most importantly, we demonstrated that using
picosecond x-ray pulses, one can accurately measure the expectation value
<cos^2 theta>(t) for impulsively aligned CF3Br molecules. We point out that a
control of the rotational dynamics opens up a novel way to imprint shapes onto
long x-ray pulses on a picosecond time scale. For our computations, we
determine the dynamic polarizability tensor of CF3Br using ab initio molecular
linear-response theory in conjunction with wave function models of increasing
sophistication: coupled-cluster singles (CCS), second-order approximate
coupled-cluster singles and doubles (CC2), and coupled-cluster singles and
doubles (CCSD).


title: Fragment Formation in Biased Random Walks

abstract:
  We analyse a biased random walk on a 1D lattice with unequal step lengths.
Such a walk was recently shown to undergo a phase transition from a state
containing a single connected cluster of visited sites to one with several
clusters of visited sites (fragments) separated by unvisited sites at a
critical probability p_c, [PRL 99, 180602 (2007)]. The behaviour of rho(l), the
probability of formation of fragments of length l is analysed. An exact
expression for the generating function of rho(l) at the critical point is
derived. We prove that the asymptotic behaviour is of the form rho(l) ~
3/[l(log l)^2].


title: Remarks on Power Spectra of Chaotic Dynamical Systems

abstract:
  We develop novel methods to compute auto-correlation functions, or power
spectral densities, for chaotic dynamical systems generated by an inverse
method whose starting point is an invariant distribution and a two-form. In
general, the inverse method makes some aspects of chaotic dynamics calculable
by methods familiar in quantum field theory. This approach has the numerical
advantage of being amenable to Monte-Carlo parallel computation. We demonstrate
the approach on a specific example, and show how auto-correlation functions can
be computed without any direct numerical simulation, by Pade approximants of a
short time expansion.

categories: nlin.CD cond-mat.stat-mech hep-th physics.flu-dyn


title: Off-resonant Raman transitions impact in an atom interferometer

abstract:
  We study the influence of off-resonant two photon transitions on high
precision measurements with atom interferometers based on stimulated Raman
transitions. These resonances induce a two photon light shift on the resonant
Raman condition. The impact of this effect is investigated in two highly
sensitive experiments: a gravimeter and a gyroscope-accelerometer. We show that
it can lead to significant systematic phase shifts, which have to be taken into
account in order to achieve best performances in term of accuracy and
stability.


title:
Asymptotic behaviour of self-contracted planar curves and gradient
  orbits of convex functions

abstract:
  We hereby introduce and study the notion of self-contracted curves, which
encompasses orbits of gradient systems of convex and quasiconvex functions. Our
main result shows that bounded self-contracted planar curves have a finite
length. We also give an example of a convex function defined in the plane whose
gradient orbits spiral infinitely many times around the unique minimum of the
function.


title: More Really is Different

abstract:
  In 1972, P.W.Anderson suggested that `More is Different', meaning that
complex physical systems may exhibit behavior that cannot be understood only in
terms of the laws governing their microscopic constituents. We strengthen this
claim by proving that many macroscopic observable properties of a simple class
of physical systems (the infinite periodic Ising lattice) cannot in general be
derived from a microscopic description. This provides evidence that emergent
behavior occurs in such systems, and indicates that even if a `theory of
everything' governing all microscopic interactions were discovered, the
understanding of macroscopic order is likely to require additional insights.


title: Extreme Value Statistics in Silicon Photonics

abstract:
  We show that fluctuations of Raman amplified pulses, in the presence of a
noisy pump, follow extreme value statistics, and provide mathematical insight
into the origin of this perplexing behavior.


title:
Maximizers for the Strichartz inequalities and the Sobolev-Strichartz
  inequalities for the Schr\"odinger equation

abstract:
  In this paper, we first show that there exists a maximizer for the
non-endpoint Strichartz inequalities for the Schr\"odinger equation in all
dimensions based on the recent linear profile decomposition results. We then
present a new proof of the linear profile decomposition for the Schr\"oindger
equation with initial data in the homogeneous Sobolev space; as a consequence,
there exists a maximizer for the Sobolev-Strichartz inequality.


title: Charging Black Saturn?

abstract:
  We construct new charged static solutions of the Einstein-Maxwell field
equations in five dimensions via a solution generation technique utilizing the
symmetries of the reduced Lagrangian. By applying our method on the
multi-Reissner-Nordstrom solution in four dimensions, we generate the
multi-Reissner-Nordstrom solution in five dimensions. We focus on the
five-dimensional solution describing a pair of charged black objects with
general masses and electric charges. This solution includes the double
Reissner-Nordstrom solution as well as the charged version of the
five-dimensional static black Saturn. However, all the black Saturn
configurations that we could find present either a conical singularity or a
naked singularity. We also obtain a non-extremal configuration of charged black
strings that reduces in the extremal limit to a Majumdar-Papapetrou like
solution in five dimensions.


title: Instanton counting on Hirzebruch surfaces

abstract:
  We perform a study of the moduli space of framed torsion free sheaves on
Hirzebruch surfaces by using localization techniques. After discussing general
properties of this moduli space, we classify its fixed points under the
appropriate toric action and compute its Poincare' polynomial. From the
physical viewpoint, our results provide the partition function of N=4
Vafa-Witten theory on Hirzebruch surfaces, which is relevant in black hole
entropy counting problems according to a conjecture due to Ooguri, Strominger
and Vafa.


title: Optimal Betti numbers of forest ideals

abstract:
  We prove a tight lower bound on the Betti numbers of tree and forest ideals
and a tight upper bound on certain graded Betti numbers of squarefree monomial
ideals.


title:
The linear profile decomposition for the Airy equation and the existence
  of maximizers for the Airy Strichartz inequality

abstract:
  In this paper, we establish the linear profile decomposition for the Airy
equation with complex or real initial data in $L^2$, respectively. As an
application, we obtain a dichotomy result on the existence of maximizers for
the symmetric Airy-Strichartz inequality.


title: Network Tomography Based on Additive Metrics

abstract:
  Inference of the network structure (e.g., routing topology) and dynamics
(e.g., link performance) is an essential component in many network design and
management tasks. In this paper we propose a new, general framework for
analyzing and designing routing topology and link performance inference
algorithms using ideas and tools from phylogenetic inference in evolutionary
biology. The framework is applicable to a variety of measurement techniques.
Based on the framework we introduce and develop several polynomial-time
distance-based inference algorithms with provable performance. We provide
sufficient conditions for the correctness of the algorithms. We show that the
algorithms are consistent (return correct topology and link performance with an
increasing sample size) and robust (can tolerate a certain level of measurement
errors). In addition, we establish certain optimality properties of the
algorithms (i.e., they achieve the optimal $l_\infty$-radius) and demonstrate
their effectiveness via model simulation.


title: Improved Approximations for Guarding 1.5-Dimensional Terrains

abstract:
  We present a 4-approximation algorithm for the problem of placing a fewest
guards on a 1.5D terrain so that every point of the terrain is seen by at least
one guard. This improves on the currently best approximation factor of 5. Our
method is based on rounding the linear programming relaxation of the
corresponding covering problem. Besides the simplicity of the analysis, which
mainly relies on decomposing the constraint matrix of the LP into totally
balanced matrices, our algorithm, unlike previous work, generalizes to the
weighted and partial versions of the basic problem.


title: On the causal gauge principle

abstract:
  Work by the Zurich school of causal (Epstein-Glaser) renormalization has
shown that renormalizability in the presence of massless or massive gauge
fields (as primary entities) explains gauge invariance and, in some instances,
the presence of a Higgs-like particle, without the Brout-Englert-Higgs-Kibble
(BEHK) mechanism. We review that work, in a pedagogical vein, with a pointer to
go beyond.


title: An Instability in Triaxial Stellar Systems

abstract:
  The radial-orbit instability is a collective phenomenon that has heretofore
only been observed in spherical systems. We find that this instability occurs
also in triaxial systems, as we checked by performing extensive N-body
simulations whose initial conditions were obtained by sampling a
self-consistent triaxial model of a cuspy galaxy composed of luminous and dark
matter. N-body simulations show a time evolution of the galaxy that is not due
to the development of chaotic motions but, rather, to the collective
instability induced by an excess of box-like orbits. The instability quickly
transforms such models into a more prolate configuration, with 0.64<b/a<0.77
and 0.6<c/a<0.7 for the dark halo and 0.64<b/a<0.77 and 0.59<c/a<0.67 for the
luminous matter. Stable triaxial, cuspy galaxies with dark matter halos are
obtained when the contribution of radially-biased orbits to the solution is
reduced. These results constitute the first evidence of the radial-orbit
instability in triaxial galaxy models.


title: PAMELA and dark matter

abstract:
  Assuming that the positron excess in PAMELA satellite data is a consequence
of annihilations of cold dark matter, we consider from a model-independent
perspective if the data show a preference for the spin of dark matter. We then
perform a general analysis of annihilations into two-body final states to
determine what weighted combination of channels best describes the data.


title:
Coupling/decoupling between translational and rotational dynamics in a
  supercooled molecular liquid

abstract:
  We use molecular dynamics computer simulations to investigate the
coupling/decoupling between translational and rotational dynamics in a
glass-forming liquid of dumbbells. This is done via a careful analysis of the
$\alpha$-relaxation time $\tau_{q^{*}}^{\rm C}$ of the incoherent
center-of-mass density correlator at the structure factor peak, the
$\alpha$-relaxation time $\tau_{2}$ of the reorientational correlator, and the
translational ($D_{t}$) and rotational ($D_{r}$) diffusion constants. We find
that the coupling between the relaxation times $\tau_{q^{*}}^{\rm C}$ and
$\tau_{2}$ increases with decreasing temperature $T$, whereas the coupling
decreases between the diffusivities $D_{t}$ and $D_{r}$. In addition, the
$T$-dependence of $D_{t}$ decouples from that of $1/\tau_{2}$, which is
consistent with previous experiments and has been interpreted as a signature of
the "translation-rotation decoupling." We trace back these apparently
contradicting observations to the dynamical heterogeneities in the system. We
show that the decreasing coupling in the diffusivities $D_{t}$ and $D_{r}$ is
only apparent due to the inadequacy of the concept of the rotational diffusion
constant for describing the reorientational dynamics in the supercooled state.
We also argue that the coupling between $\tau_{q^{*}}^{\rm C}$ and $\tau_{2}$
and the decoupling between $D_{t}$ and $1/\tau_{2}$, both of which strengthen
upon cooling, can be consistently understood in terms of the growing dynamic
length scale.


title:
Graph algebras, Exel-Laca algebras, and ultragraph algebras coincide up
  to Morita equivalence

abstract:
  We prove that the classes of graph algebras, Exel-Laca algebras, and
ultragraph algebras coincide up to Morita equivalence. This result answers the
long-standing open question of whether every Exel-Laca algebra is Morita
equivalent to a graph algebra. Given an ultragraph G we construct a directed
graph E such that C*(G) is isomorphic to a full corner of C*(E). As
applications, we characterize real rank zero for ultragraph algebras and
describe quotients of ultragraph algebras by gauge-invariant ideals.


title:
Reduced Dynamics from the Unitary Group to Some Flag Manifolds :
  Interacting Matrix Riccati Equations

abstract:
  In this paper we treat the time evolution of unitary elements in the N level
system and consider the reduced dynamics from the unitary group U(N) to flag
manifolds of the second type (in our terminology). Then we derive a set of
differential equations of matrix Riccati types interacting with one another and
present an important problem on a nonlinear superposition formula that the
Riccati equation satisfies.
  Our result is a natural generalization of the paper {\bf Chaturvedi et al}
(arXiv : 0706.0964 [quant-ph]).


title: Some Hecke Algebra Products and Corresponding Random Walks

abstract:
  Let $\bm{i}=1+q+...+q^{i-1}$. For certain sequences $(r_1,...,r_l)$ of
positive integers, we show that in the Hecke algebra $\mathscr{H}_n(q)$ of the
symmetric group $\mathfrak{S}_n$, the product $(1+\bm{r_1}T_{r_1})...
(1+\bm{r_l}T_{r_l})$ has a simple explicit expansion in terms of the standard
basis $\{T_w\}$. An interpretation is given in terms of random walks on
$\mathfrak{S}_n$.


title:
Experimental demonstration of self-collimation beaming and splitting in
  photonic crystals

abstract:
  I studied experimentally the beam self-collimation and splitting in
two-dimensional microwave photonic crystals. Using a microwave photonic crystal
fabricated from alumina rods, I present an experimental proof of principle for
an earlier theoretical proposal [A. Matthews et al., Opt. Commun. 279, 313
(2007)] of a photonic crystal beam splitter based on the self-collimation
effect.


title:
Phase transition from quark-meson coupling hyperonic matter to
  deconfined quark matter

abstract:
  We investigate the possibility and consequences of phase transitions from an
equation of state (EOS) describing nucleons and hyperons interacting via mean
fields of sigma, omega, and rho mesons in the recently improved quark-meson
coupling (QMC) model to an EOS describing a Fermi gas of quarks in an MIT bag.
The transition to a mixed phase of baryons and deconfined quarks, and
subsequently to a pure deconfined quark phase, is described using the method of
Glendenning. The overall EOS for the three phases is calculated for various
scenarios and used to calculate stellar solutions using the
Tolman-Oppenheimer-Volkoff equations. The results are compared with recent
experimental data, and the validity of each case is discussed with consequences
for determining the species content of the interior of neutron stars.


title:
Deformed quasiparticle-random-phase approximation for neutron-rich
  nuclei using the Skyrme energy density functional

abstract:
  We develop a new framework of the deformed quasiparticle-random-phase
approximation (QRPA) where the Skyrme density functional and the
density-dependent pairing functional are consistently treated. Numerical
applications are carried out for the isovector dipole and the isoscalar
quadrupole modes in the spherical $^{20}$O and in the deformed $^{26}$Ne
nuclei, and the effect of the momentum dependent terms of the Skyrme effective
interaction for the energy-weighted sum rule is discussed. As a further
application, we present for the first time the moments of inertia of $^{34}$Mg
and $^{36}$Mg using the Thouless-Valatin procedure based on the self-consistent
deformed QRPA, and show the applicability of our new calculation scheme not
only for the vibrational modes but also for the rotational modes in
neutron-rich nuclei.


title: Bimodality and Coulomb effects with a canonical thermodynamic model

abstract:
  The effect of the Coulomb interaction on the phase diagram of finite nuclei
is studied within the Canonical Thermodynamic Model. If Coulomb effects are
artificially switched off, this model shows a phenomenology consistent with the
liquid-gas phase transition. The inclusion of Coulomb does not significantly
affect the phase diagram but it drastically modifies the nature and order
parameter of the transition. A clear understanding of the phenomenon can be
achieved looking at the distribution of the largest fragment produced in each
fragmentation event. Possible connections with experimental observations are
outlined.


title: Universal scaling for the jamming transition

abstract:
  The existence of universal scaling in the vicinity of the jamming transition
of sheared granular materials is predicted by a phenomenology. The critical
exponents are explicitly determined, which are independent of the spatial
dimension. The validity of the theory is verified by the molecular dynamics
simulation.


title: A Jupiter-like Planet Orbiting the Nearby M Dwarf GJ832

abstract:
  Precision Doppler velocity measurements from the Anglo-Australian Tele- scope
reveal a planet with a 9.4+/-0.4 year period orbiting the M1.5 dwarf GJ 832.
Within measurement uncertainty the orbit is circular, and the minimum mass (m
sin i) of the planet is 0.64+/-0.06 MJUP. GJ 832 appears to be depleted in met-
als by at least 50% relative to the Sun, as are a significant fraction of the M
dwarfs known to host exoplanets. GJ 832 adds another Jupiter-mass planet to the
known census of M dwarf exoplanets, which currently includes a significant
number of Neptune-mass planets. GJ 832 is an excellent candidate for astromet-
ric orbit determination with alpha sin i = 0.95 mas. GJ 832b has the second
largest angular distance from its star among radial velocity detected
exoplanets (0.69 arc sec) making it a potentially interesting target for future
direct detection.


title:
Quantum phase diagram of a spin-1/2 antiferromagnetic chain with
  magnetic impurity

abstract:
  We present the renormalization group (RG) flow diagram of a spin-half
antiferromagnetic chain with magnetic impurity and one altered link. In this
two parameters (competing interactions) model, one can find the complex phase
diagram with many interesting fixed points. There is no evidence of
intermediate stable fixed point in weak coupling phase. It may arise at the
strong coupling phase. Depending on the strength of couplings the phases
correspond either to a decoupled spin with Curie law behavior or a
logarithmically diverging impurity susceptibility as in the two channel Kondo
problem.


title: Heisenberg relations in the general case

abstract:
  The Heisenberg relations are derived in a quite general setting when the
field transformations are induced by three representations of a given group.
They are considered also in the fibre bundle approach. The results are
illustrated in a case of transformations induced by the Poincare group.


title: Superconformal defects in the tricritical Ising model

abstract:
  We study superconformal defect lines in the tricritical Ising model in 2
dimensions. By the folding trick, a superconformal defect is mapped to a
superconformal boundary of the N=1 superconformal unitary minimal model of
c=7/5 with D_6-E_6 modular invariant. It turns out that the complete set of the
boundary states of c=7/5 D_6-E_6 model cannot be interpreted as the consistent
set of superconformal defects in the tricritical Ising model since it does not
contain the "no defect" boundary state. Instead, we find a set of 18 consistent
superconformal defects including "no defect" and satisfying the Cardy
condition. This set also includes some defects which are not purely
transmissive or purely reflective.


title:
Diophantine Exponents of Affine Subspaces: The Simultaneous
  Approximation Case

abstract:
  We apply nondivergence estimates for flows on homogeneous spaces to compute
Diophantine exponents of affine subspaces of $\R^n$ and their nondegenerate
submanifolds.


title: Limit theorems for additive functionals of a Markov chain

abstract:
  Consider a Markov chain $\{X_n\}_{n\ge 0}$ with an ergodic probability
measure $\pi$. Let $\Psi$ a function on the state space of the chain, with
$\alpha$-tails with respect to $\pi$, $\alpha\in (0,2)$. We find sufficient
conditions on the probability transition to prove convergence in law of
$N^{1/\alpha}\sum_n^N \Psi(X_n)$ to a $\alpha$-stable law. ``Martingale
approximation'' approach and ``coupling'' approach give two different sets of
conditions. We extend these results to continuous time Markov jump processes
$X_t$, whose skeleton chain satisfies our assumptions. If waiting time between
jumps has finite expectation, we prove convergence of $N^{-1/\alpha}\int_0^{Nt}
V(X_s) ds$ to a stable process. In the case of waiting times with infinite
average, we prove convergence to a Mittag-Leffler process.


title:
Functions measuring smoothness and the constants in Jackson--Stechkin
  theorem

abstract:
  This paper is devoted to the equivalence of two type direct theorems in
Approximation Theory: a) for smooth functions (Favard's estimates). b) for
arbitrary continuous function (Jackson--Stechkin estimates). Specifically, we
will show that Jackson--Stechkin inequality with optimal respect to the order
of smoothness constants follows from Favard's inequality.


title: The Cambrian impact hypothesis

abstract:
  After a thorough research on the circumstantial changes and the great
evolution of life in the Cambrian period, the author propounds such a
hypothesis: During the Late Precambrian, about 500-600Ma, a celestial body
impacted the Earth. The high temperature ended the great glaciation,
facilitated the communication of biological information. The rapid change of
Earth environment enkindled the genesis-control system, and released the HSP-90
variations. After the impact, benefited from the protection of the new ozone
layer and the energy supplement of the aerobic respiration, those survived
underground life exploded. They generated carapaces and complex metabolism to
adjust to the new circumstance of high temperature and high pressure.
  This article uses a large amount of analyses and calculations, and
illustrates that this hypothesis fits well with most of the important
incidences in astronomic and geologic discoveries.


title: Local Fourier transform and epsilon factors

abstract:
  Laumon introduced the local Fourier transform for $\ell$-adic Galois
representations of local fields, of equal characteristic $p$ different from
$\ell$, as a powerful tool to study the Fourier-Deligne transform of
$\ell$-adic sheaves over the affine line. In this article, we compute
explicitly the local Fourier transform of monomial representations satisfying a
certain ramification condition, and deduce Laumon's formula relating the
epsilon factor to the determinant of the local Fourier transform under the same
condition.


title:
Application of the level-set method to the implicit solvation of
  nonpolar molecules

abstract:
  A level-set method is developed for numerically capturing the equilibrium
solute-solvent interface that is defined by the recently proposed variational
implicit solvent model (Dzubiella, Swanson, and McCammon, Phys. Rev. Lett. {\bf
104}, 527 (2006) and J. Chem.\Phys. {\bf 124}, 084905 (2006)). In the level-set
method, a possible solute-solvent interface is represented by the zero
level-set (i.e., the zero level surface) of a level-set function and is
eventually evolved into the equilibrium solute-solvent interface. The evolution
law is determined by minimization of a solvation free energy {\it functional}
that couples both the interfacial energy and the van der Waals type
solute-solvent interaction energy. The surface evolution is thus an energy
minimizing process, and the equilibrium solute-solvent interface is an output
of this process. The method is implemented and applied to the solvation of
nonpolar molecules such as two xenon atoms, two parallel paraffin plates,
helical alkane chains, and a single fullerene $C_{60}$. The level-set solutions
show good agreement for the solvation energies when compared to available
molecular dynamics simulations. In particular, the method captures solvent
dewetting (nanobubble formation) and quantitatively describes the interaction
in the strongly hydrophobic plate system.


title: Second Renormalization of Tensor-Network States

abstract:
  We propose a second renormalization group method to handle the tensor-network
states or models. This method reduces dramatically the truncation error of the
tensor renormalization group. It allows physical quantities of classical
tensor-network models or tensor-network ground states of quantum systems to be
accurately and efficiently determined.

categories: cond-mat.str-el cond-mat.stat-mech physics.comp-ph quant-ph


title: Unknotting sequences for torus knots

abstract:
  The unknotting number of a knot is bounded from below by its slice genus. It
is a well-known fact that the genera and unknotting numbers of torus knots
coincide. In this note we characterize quasipositive knots for which the genus
bound is sharp: the slice genus of a quasipositive knot equals its unknotting
number, if and only if the given knot appears in an unknotting sequence of a
torus knot.


title: Relaxing Lorentz invariance in general perturbative anomalies

abstract:
  We analyze the role of Lorentz symmetry in the perturbative non-gravitational
anomalies for a single family of fermions. The theory is assumed to be
translational invariant, power-counting renormalizable and based on a local
action, but is allowed to have general Lorentz violating operators. We study
the conservation of global and gauge currents associate with general internal
symmetry groups and find, by using a perturbative approach, that Lorentz
symmetry does not participate in the clash of symmetries that leads to the
anomalies. We first analyze the triangle graphs and prove that there are
regulators for which the anomalous part of the Ward identities exactly
reproduces the Lorentz invariant case. Then we show, by means of a regulator
independent argument, that the anomaly cancellation conditions derived in
Lorentz invariant theories remain necessary ingredients for anomaly freedom.


title:
Monitoring the Bragg peak location of 73 MeV/u carbon ions by means of
  prompt $\gamma$-ray measurements

abstract:
  By means of a time-of-flight technique, we measured the longitudinal profile
of prompt $\gamma$-rays emitted by 73 MeV/u $^{13}$C ions irradiating a PMMA
target. This technique allowed us to minimize the shielding against neutrons
and scattered $\gamma$-rays, and to correlate prompt gamma emission to the ion
path. This correlation, together with a high counting rate, paves the way
toward real-time monitoring of the longitudinal dose profile during ion therapy
treatments. Moreover, the time correlation between the prompt gamma detection
and the transverse position of the incident ions measured by a beam monitor can
provide real-time 3D control of the irradiation.


title: Subelliptic Estimates for Quadratic Differential Operators

abstract:
  We prove global subelliptic estimates for quadratic differential operators.
Quadratic differential operators are operators defined in the Weyl quantization
by complex-valued quadratic symbols. In a previous joint work with M. Hitrik,
we pointed out the existence of a particular linear subvector space in the
phase space intrinsically associated to their Weyl symbols, called singular
space, which rules spectral properties of non-elliptic quadratic operators. The
purpose of the present paper is to prove that quadratic operators whose
singular spaces are reduced to zero, are subelliptic with a loss of
"derivatives" depending directly on particular algebraic properties of the
Hamilton maps of their Weyl symbols. More generally, when singular spaces are
symplectic spaces, we prove that quadratic operators are subelliptic in any
direction of the symplectic orthogonal complements of their singular spaces.


title:
CoRoT and stellar activity: preliminary results from the modelling of
  CoRoT-Exo-2a

abstract:
  We present a preliminary analysis of the photospheric activity of
CoRoT-Exo-2a, a young G7V star accompanied by a transiting hot Jupiter recently
discovered by CoRoT. We apply spot modelling techniques developed for the
analysis of the Sun as a star and capable to extract from CoRoT high precision
light curves information on the variation of the total spotted area and the
longitude of active regions along the 142 days of the observations. This
preliminary analysis shows that the active regions form within two active
longitudes separated by about 180 degrees and rotating with periods of 4.5221
and 4.5543 days, respectively, and that the total spotted area oscillates with
a period of about 28.9 days.


title: Approximating Transitivity in Directed Networks

abstract:
  We study the problem of computing a minimum equivalent digraph (also known as
the problem of computing a strong transitive reduction) and its maximum
objective function variant, with two types of extensions. First, we allow to
declare a set $D\subset E$ and require that a valid solution $A$ satisfies
$D\subset A$ (it is sometimes called transitive reduction problem). In the
second extension (called $p$-ary transitive reduction), we have integer edge
labeling and we view two paths as equivalent if they have the same beginning,
ending and the sum of labels modulo $p$. A solution $A\subseteq E$ is valid if
it gives an equivalent path for every original path. For all problems we
establish the following: polynomial time minimization of $|A|$ within ratio
1.5, maximization of $|E-A|$ within ratio 2, MAX-SNP hardness even of the
length of simple cycles is limited to 5. Furthermore, we believe that the
combinatorial technique behind the approximation algorithm for the minimization
version might be of interest to other graph connectivity problems as well.


title:
Temporal variability of GRB early X-ray afterglows and GRB080319B prompt
  emission

abstract:
  We performed the first systematic search for the minimum variability time
scale between 0.3 and 10 keV studying the 28 brightest early (<3000 s)
afterglows detected by Swift-XRT up to March 2008. We adopt the power spectrum
analysis in the time domain: unlike the Fourier spectrum, this is suitable to
study the rms variations at different time-scales. We find that early XRT
afterglows show variability in excess of the Poissonian noise level on
time-scales as short as about 1 s (rest frame value), with the shortest t_{min}
associated with the highest energy band. The gamma-ray prompt emission of
GRB080319B shows a characteristic average variability time-scale t_{var} of
about 1s; this parameter undergoes a remarkable evolution during the prompt
emission (BAT observation).


title: The Concepts of "Age" and "Universality" in Cosmic Ray Showers

abstract:
  The concept of "age" as a parameter for the description of the state of
development of high energy showers in the atmosphere has been in use in cosmic
ray studies for several decades. In this work we briefly discuss how this
concept, originally introduced to describe the average behavior of
electromagnetic cascades, can be fruitfully applied to describe individual
showers generated by primary particles of different nature, including protons,
nuclei and neutrinos. Showers with the same age share three different important
properties: (i) their electron size has the same fractional rate of change with
increasing depth, (ii) the bulk of the electrons and photons in the shower
(excluding high energy particles) have energy spectra with shapes and relative
normalization uniquely determined by the age parameter, (iii) the electrons and
photons in the shower have also the same angular and lateral distributions
sufficiently far from the shower axis. In this work we discuss how the
properties associated with the shower age can be understood with simple
arguments, and how the shapes of the electron and photon spectra and the
relative normalization that correspond to a certain age can be calculated
analytically.


title: Towards a model independent approach to fragmentation functions

abstract:
  We show that the difference cross sections in unpolarized SIDIS e+N\to e+h+X
and pp hadron production p+p\to h+X determine independently in a model
independent way, in any order in QCD, the two FFs: D_u^{h-\bar h} and
D_d^{h-\bar h}, h=\pi^\pm, K^\pm or a sum over charged hadrons. If both K^\pm
and K_s^0 are measured, then e+e-\toK+X, e+N\to e+K+X and p+p\to K+X present
independent measurements of just one FF: D_{u-d}^{K^++K^-}. The above results
allow to test the existing parametrizations, obtained with various different
assumptions about the FFs, and to test the $Q^2$ evolution and factorization.


title: Quantum transport in ferromagnetic Permalloy nanostructures

abstract:
  We studied phase coherent phenomena in mesoscopic Permalloy samples by
exploring low temperature transport. Both, differential conductance as a
function of bias voltage and magnetoconductance of individual wires display
conductance fluctuations. Analysis of these fluctuations yields a phase
coherence length of $\sim250$ nm at 25 mK as well as a $1/\sqrt{T}$ temperature
dependence. To suppress conductance fluctuations by ensemble averaging we
investigated low temperature transport in wire arrays and extended Permalloy
films. In these samples we have measured conductance corrections which stem
from electron-electron interaction (EEI) but attempts to detect signatures of
weak localization were without success.


title: The 1,2-coloured HOMFLY-PT link homology

abstract:
  In this paper we define the 1,2-coloured HOMFLY-PT link homology and prove
that it is a link invariant. We conjecture that this homology categorifies the
coloured HOMFLY-PT polynomial for links whose components are labelled 1 or 2.