title: Determinant computations for some classes of Toeplitz-Hankel matrices

abstract:
  The purpose of this paper is to compute the asymptotics of determinants of
finite sections of operators that are trace class perturbations of Toeplitz
operators. For example, we consider the asymptotics in the case where the
matrices are of the form $ (a_{i-j} \pm a_{i+j+1-k})_{i,j=0... N-1} $ with $k$
is fixed. We will show that this example as well as some general classes of
operators have expansions that are similar to those that appear in the Strong
Szeg\"{o} Limit Theorem. We also obtain exact identitities for some of the
determinants that are analogous to the one derived independently by Geronimo
and Case and by Borodin and Okounkov for finite Toeplitz matrices. These
problems were motivated by considering certain statistical quantities that
appear in random matrix theory.


title: (q,t)-analogues and GL_n(F_q)

abstract:
  We start with a (q,t)-generalization of a binomial coefficient. It can be
viewed as a polynomial in t that depends upon an integer q, with combinatorial
interpretations when q is a positive integer, and algebraic interpretations
when q is the order of a finite field. These (q,t)-binomial coefficients and
their interpretations generalize further in two directions, one relating to
column-strict tableaux and Macdonald's ``seventh variation'' of Schur
functions, the other relating to permutation statistics and Hilbert series from
the invariant theory of GL_n(F_q).


title: Blandford's Argument: The Strongest Continuous Gravitational Wave Signal

abstract:
  For a uniform population of neutron stars whose spin-down is dominated by the
emission of gravitational radiation, an old argument of Blandford states that
the expected gravitational-wave amplitude of the nearest source is independent
of the deformation and rotation frequency of the objects. Recent work has
improved and extended this argument to set upper limits on the expected
amplitude from neutron stars that also emit electromagnetic radiation. We
restate these arguments in a more general framework, and simulate the evolution
of such a population of stars in the gravitational potential of our galaxy. The
simulations allow us to test the assumptions of Blandford's argument on a
realistic model of our galaxy. We show that the two key assumptions of the
argument (two dimensionality of the spatial distribution and a steady-state
frequency distribution) are in general not fulfilled. The effective scaling
dimension D of the spatial distribution of neutron stars is significantly
larger than two, and for frequencies detectable by terrestrial instruments the
frequency distribution is not in a steady state unless the ellipticity is
unrealistically large. Thus, in the cases of most interest, the maximum
expected gravitational-wave amplitude does have a strong dependence on the
deformation and rotation frequency of the population. The results strengthen
the previous upper limits on the expected gravitational-wave amplitude from
neutron stars by a factor of 6 for realistic values of ellipticity.


title: Operator Imprecision and Scaling of Shor's Algorithm

abstract:
  Shor's algorithm (SA) is a quantum algorithm for factoring integers. Since SA
has polynomial complexity while the best classical factoring algorithms are
sub-exponential, SA is cited as evidence that quantum computers are more
powerful than classical computers. SA is critically dependent on the Quantum
Fourier Transform (QFT) and it is known that the QFT is sensitive to errors in
the quantum state input to it. In this paper, we show that the polynomial
scaling of SA is destroyed by input errors to the QFT part of the algorithm. We
also show that Quantum Error Correcting Codes (QECC) are not capable of
suppressing errors due to operator imprecision and that propagation of operator
precision errors is sufficient to severely degrade the effectiveness of SA.
Additionally we show that operator imprecision in the error correction circuit
for the Calderbank-Shor-Steane QECC is mathematically equivalent to decoherence
on every physical qubit in a register. We conclude that, because of the effect
of operator precision errors, it is likely that physically realizable quantum
computers will be capable of factoring integers no more efficiently than
classical computers.


title:
Steady-state nonequilibrium density of states of driven strongly
  correlated lattice models in infinite dimensions

abstract:
  The formalism for exactly calculating the retarded and advanced Green's
functions of strongly correlated lattice models in a uniform electric field is
derived within dynamical mean-field theory. To illustrate the method, we solve
for the nonequilibrium density of states of the Hubbard model in both the
metallic and Mott insulating phases at half-filling (with an arbitrary strength
electric field) by employing the numerical renormalization group as the
impurity solver. This general approach can be applied to any strongly
correlated lattice model in the limit of large dimensions.


title: Constraining Maximally Supersymmetric Membrane Actions

abstract:
  We study the recent construction of maximally supersymmetric field theory
Lagrangians in three spacetime dimensions that are based on algebras with a
triple product. Assuming that the algebra has a positive definite metric
compatible with the triple product, we prove that the only non-trivial examples
are either the well known case based on a four dimensional algebra or direct
sums thereof.


title:
First measurement of target and double spin asymmetries for polarized e-
  polarized p --> e p pi0 in the nucleon resonance region above the Delta(1232)

abstract:
  The exclusive channel polarized proton(polarized e,e prime p)pi0 was studied
in the first and second nucleon resonance regions in the Q2 range from 0.187 to
0.770 GeV2 at Jefferson Lab using the CEBAF Large Acceptance Spectrometer
(CLAS). Longitudinal target and beam-target asymmetries were extracted over a
large range of center-of-mass angles of the pi0 and compared to the unitary
isobar model MAID, the dynamic model by Sato and Lee, and the dynamic model
DMT. A strong sensitivity to individual models was observed, in particular for
the target asymmetry and in the higher invariant mass region. This data set,
once included in the global fits of the above models, is expected to place
strong constraints on the electrocoupling amplitudes A_{1/2} and S_{1/2} for
the Roper resonance N(1400)P11, and the N(1535)S11 and N(1520)D13 states.


title: Logic and String Theory

abstract:
  The unification of Quantum Mechanics and General Relativity remains the
primary goal of Theoretical Physics, with string theory appearing as the only
plausible unifying scheme. In the present work, in a search of the conceptual
foundations of string theory, we analyze the relational logic developed by C.
S. Peirce in the late nineteenth century. The Peircean logic has the
mathematical structure of a category with the relation $R_{ij}$ among two
individual terms $S_i$ and $S_j$, serving as an arrow (or morphism). We
introduce a realization of the corresponding categorical algebra of
compositions, which naturally gives rise to the fundamental quantum laws, thus
underscoring the relational character of Quantum Mechanic. The same relational
algebra generates a number of group structures, among them $W_{\infty}$. The
group $W_{\infty}$ is embodied and realized by the matrix models, themselves
closely linked with string theory. It is suggested that relational logic and in
general category theory may provide a new paradigm, within which to develop
modern physical theories.


title: Structural Evolution of the Brazilian Airport Network

abstract:
  The aviation sector is profitable, but sensitive to economic fluctuations,
geopolitical constraints and governmental regulations. As for other means of
transportation, the relation between origin and destination results in a
complex map of routes, which can be complemented by information associated to
the routes themselves, for instance, frequency, traffic load or distance. The
theory of networks provides a natural framework to investigate dynamics on the
resulting structure. Here, we investigate the structure and evolution of the
Brazilian Airport Network (BAN) for several quantities: routes, connections,
passengers and cargo. Some structural features are in accordance with previous
results of other airport networks. The analysis of the evolution of the BAN
shows that its structure is dynamic, with changes in the relative relevance of
some airports and routes. The results indicate that the connections converge to
specific routes. The network shrinks at the route level but grows in number of
passengers and amount of cargo, which more than doubled during the period
studied.


title: Squashing Models for Optical Measurements in Quantum Communication

abstract:
  Measurements with photodetectors necessarily need to be described in the
infinite dimensional Fock space of one or several modes. For some measurements
a model has been postulated which describes the full mode measurement as a
composition of a mapping (squashing) of the signal into a small dimensional
Hilbert space followed by a specified target measurement. We present a
formalism to investigate whether a given measurement pair of mode and target
measurements can be connected by a squashing model. We show that the
measurements used in the BB84 protocol do allow a squashing description,
although the six-state protocol does not. As a result, security proofs for the
BB84 protocol can be based on the assumption that the eavesdropper forwards at
most one photon, while the same does not hold for the six-state protocol.


title:
Electron and Spin Transport in the Presence of Complex Absorbing
  Potential

abstract:
  We examine the impact of a complex absorbing potential on electron transport,
both in the continuum and on a lattice. This requires the use of non-Hermitian
Hamiltonians; the required formalism is briefly outlined. The lattice
formulation allows us to study the interesting problem of an electron
interacting with a stationary spin, and the subsequent time evolution of the
electron and spin properties as the electron is absorbed after the initial
interaction. Remarkably, the properties of the localized spin are affected
'at-a-distance' by the interaction of the (now entangled) electron with a
complex potential.


title:
Neutralino Dark Matter in minimal supersymmetric standard model with
  natural light Higgs sector

abstract:
  We study the neutralino relic density in the minimal supersymmetric standard
model with natural light Higgs sector in which all Higgs masses, the
supersymmetry (SUSY) breaking parameters, and the higgsino mass parameter mu
are of order the weak scale. To realize this situation we adopt nonuniversal
Higgs masses at the grand unified scale. We show that in some parameter space
in which the SUSY breaking parameters are comparatively small, not only the
constraint from the observed relic density of dark matter but also the LEP
Higgs bound and the constraint from the b ->s gamma process are satisfied. In
most of the parameter space, the neutralino relic density becomes smaller than
the observed relic density in contrast with the results in the constrained
minimal SUSY standard model (CMSSM). The reason is that the neutralino
coannihilation processes to Higgs bosons open even if the gaugino mass is small
and the cross sections become large due to the small dimensionful parameters.
Especially small mu parameter and the light CP-odd Higgs, which are difficult
to be realized in the CMSSM, are essential for the result.


title:
Current-current correlations in the three-band model for two-leg CuO
  ladders

abstract:
  We study current-current correlations in the three-band Hubbard model for
two-leg CuO ladders using the density-matrix renormalization group method. We
find that these correlations decrease exponentially with distance for low
doping but as a power law for higher doping. Their pattern is compatible with
the circulating current (CC) phase which Varma has proposed to explain the
pseudo-gaped metallic phase in underdoped high-temperature superconductors.
However, for model parameters leading to a realistic ground state in the
undoped ladder, the current fluctuations decay faster than the d-wave-like
pairing correlations in the doped state. Thus we conclude that no phase with CC
order or dominant CC fluctuations occur in the three-band model of two-leg CuO
ladders.


title: Teaching superfluidity at the introductory level

abstract:
  Standard introductory modern physics textbooks do not exactly dwell on
superfluidity in 4He. Typically, Bose-Einstein condensation (BEC) is mentioned
in the context of an ideal Bose gas, followed by the statement that BEC happens
in 4He and that the ground state of 4He exhibits many interesting properties
such as having zero viscosity. Not only does this approach not explain in any
way why 4He becomes a superfluid, it denies students the opportunity to learn
about the far reaching consequences of energy gaps as they develop in both
superfluids and superconductors. We revisit superfluid 4He by starting with
Feynman's explanation of superfluidity based on Bose statistics as opposed to
BEC, and we present exercises for the students that allow them to arrive at a
very accurate estimate of the superfluid transition temperature and of the
energy gap separating the ground state from the first excited state. This paper
represents a self-contained account of superfluidity, which can be covered in
one or two lessons in class.


title: Controlling coherence using the internal structure of hard pi pulses

abstract:
  The tiny difference between hard pi pulses and their delta-function
approximation can be exploited to control coherence. Variants on the magic echo
that work despite a large spread in resonance offsets are demonstrated using
the zeroth- and first-order average Hamiltonian terms, for 13-C NMR in C60. The
29-Si NMR linewidth of Silicon has been reduced by a factor of about 70,000
using this approach, which also has potential applications in magnetic
resonance microscopy and imaging of solids.


title: Refined convergence for the Boolean model

abstract:
  In a previous work, two of the authors proposed a new proof of a well known
convergence result for the scaled elementary connected vacant component in the
high intensity Boolean model towards the Crofton cell of the Poisson hyperplane
process. In this paper, we consider the particular case of the two-dimensional
Boolean model where the grains are discs with random radii. We investigate the
second-order term in this convergence when the Boolean model and the Poisson
line process are coupled on the same probability space. A precise coupling
between the Boolean model and the Poisson line process is first established, a
result of directional convergence in distribution for the difference of the two
sets involved is derived as well.


title:
A characterization of dimension free concentration in terms of
  transportation inequalities

abstract:
  The aim of this paper is to show that a probability measure concentrates
independently of the dimension like a gaussian measure if and only if it
verifies Talagrand's $\T_2$ transportation-cost inequality. This theorem
permits us to give a new and very short proof of a result of Otto and Villani.
Generalizations to other types of concentration are also considered. In
particular, one shows that the Poincar\'e inequality is equivalent to a certain
form of dimension free exponential concentration. The proofs of these results
rely on simple Large Deviations techniques.


title:
On the solutions of multicomponent generalizations of the Lam{\'e}
  equation

abstract:
  We describe a class of the singular solutions to the multicomponent analogs
of the Lam{\'e} equation, arising as equations of motion of the elliptic
Calogero--Moser systems of particles carrying spin 1/2. At special value of the
coupling constant we propose the ansatz which allows one to get meromorphic
solutions with two arbitrary parameters. They are quantized upon the
requirement of the regularity of the wave function on the hyperplanes at which
particles meet and imposing periodic boundary conditions. We find also the
extra integrals of motion for three-particle systems which commute with the
Hamiltonian for arbitrary values of the coupling constant.


title: The Cosmic Evolution of Metallicity from the SDSS Fossil Record

abstract:
  We present the time evolution of the stellar metallicity for SDSS galaxies, a
sample that spans five orders of magnitude in stellar mass (10^7 - 10^{12}
Msun). Assuming the BC03 stellar population models, we find that more massive
galaxies are more metal-rich than less massive ones at all redshifts; the
mass-metallicity relation is imprinted in galaxies from the epoch of formation.
For galaxies with present stellar masses > 10^{10} Msun, the time evolution of
stellar metallicity is very weak, with at most 0.2-0.3 dex over a Hubble time-
for this reason the mass-metallicity relation evolves little with redshift.
However, for galaxies with present stellar masses < 10^{10} Msun, the evolution
is significant, with metallicity increasing by more than a decade from redshift
3 to the present. By being able to recover the metallicity history, we have
managed to identify the origin of a recent discrepancy between the metallicity
recovered from nebular lines and absorption lines. As expected, we show that
the young population dominates the former while the old population the latter.
We have investigated the dependence on the stellar models used and find that
older stellar population synthesis codes do not produce a clear result.
Finally, we have explored the relationship between cluster environment and
metallicity, and find a strong correlation in the sense that galaxies in high
density regions have high metallicity.


title:
Transforming the Einstein static Universe into physically acceptable
  static fluid spheres

abstract:
  The staid subject of exact static spherically symmetric perfect fluid
solutions of Einstein's equations has been reinvigorated in the last decade. We
now have several solution generating techniques which give rise to new exact
solutions. Here the Einstein static Universe is transformed into a physically
acceptable solution the properties of which are examined in detail. The
emphasis here is on the importance of the integration constants that these
generating techniques introduce.


title:
Non-linear magnetotransport in microwave-illuminated two-dimensional
  electron systems

abstract:
  We study magnetoresistivity oscillations in a high-mobility two-dimensional
electron system subject to both microwave and dc electric fields. First, we
observe that the oscillation amplitude is a periodic function of the inverse
magnetic field and is strongly suppressed at microwave frequencies near
half-integers of the cyclotron frequency. Second, we obtain a complete set of
conditions for the differential resistivity extrema and saddle points. These
findings indicate the importance of scattering without microwave absorption and
a special role played by microwave-induced scattering events antiparallel to
the electric field.


title:
Double Exchange Model at Low Densities: Magnetic Polarons and Coulomb
  Suppressed Phase Separation

abstract:
  We consider the double exchange model at very low densities. The conditions
for the formation of self-trapped magnetic polarons are analyzed using an
independent polaron model. The issue of phase separation in the low density
region of the temperature-density phase diagram is discussed. We show how
electrostatic and localization effects can lead to the substantial suppression
of the phase separated regime. By examining connections between the resulting
phase and the polaronic phase, we conclude that they reflect essentially the
same physical situation of a ferromagnetic droplet containing one single
electron. In the ultra diluted regime, we explore the possible stabilization of
a Wigner crystal of magnetic polarons. Our results are compared with the
experimental evidence for a polaronic phase in europium hexaboride, and we are
able to reproduce the experimental region of stability of the polaronic phase.
We further demonstrate that phase-separation is a general feature expected in
metallic ferromagnets whose bandwidth depends on the magnetization.


title: FUSE Deuterium Observations: A Strong Case For Galactic Infall

abstract:
  Measurements of deuterium in the local interstellar medium have revealed
large variations in D/H along different lines of sight. Moreover, recent {\it
Far Ultraviolet Spectroscopic Explorer} (FUSE) measurements find D/H to be
anticorrelated with several indicators of dust formation and survival,
suggesting that interstellar deuterium suffers significant depletion onto dust
grains. This in turn implies that the total deuterium abundance in the local
Galactic disk could be as high as $\sim 84 %$ of the primordial D abundance. It
was proposed that the infall/accretion of pristine gas is needed to explain
such a high deuterium abundance. However, we point out that the infall needed
to maintain a high present-day D/H is, within the preferred models, in tension
with observations that gas represents only some $\sim 20%$ of Galactic baryons,
with the balance in stars. We study this tension in the context of a wide class
of Galactic evolution models for baryonic processing through stars, which show
that deuterium destruction is strongly and cleanly correlated with the drop in
the gas fraction. We find that FUSE deuterium observations and Galactic gas
fraction estimates can be reconciled in some models; these demand a significant
infall rate of pristine material that almost completely balances the rate of
star formation. These successful models also require that the average fraction
of gas that is returned by dying stars is less than 40% of the initial stellar
mass. Cosmological implications of dust depletion of D in high-redshift systems
are discussed.


title: Theory of magnetically powered jets

abstract:
  The magnetic theory for the production of jets by accreting objects is
reviewed with emphasis on outstanding problem areas. An effort is made to show
the connections behind the occasionally diverging nomenclature in the
literature, to contrast the different points of view about basic mechanisms,
and to highlight concepts for interpreting the results of numerical
simulations. The role of dissipation of magnetic energy in accelerating the
flow is discussed, and its importance for explaining high Lorentz factors. The
collimation of jets to the observed narrow angles is discussed, including a
critical discussion of the role of `hoop stress'. The transition between disk
and outflow is one of the least understood parts of the magnetic theory; its
role in setting the mass flux in the wind, in possible modulations of the mass
flux, and the uncertainties in treating it realistically are discussed. Current
views on most of these problems are still strongly influenced by the
restriction to 2 dimensions (axisymmetry) in previous analytical and numerical
work; 3-D effects likely to be important are suggested. An interesting problem
area is the nature and origin of the strong, preferably highly ordered magnetic
fields known to work best for jet production. The observational evidence for
such fields and their behavior in numerical simulations is discussed. I argue
that the presence or absence of such fields may well be the `second parameter'
governing not only the presence of jets but also the X-ray spectra and timing
behavior of X-ray binaries.


title: Antibonding ground states in semiconductor artificial molecules

abstract:
  The spin-orbit interaction is a crucial element of many semiconductor
spintronic technologies. Here we report the first experimental observation, by
magneto-optical spectroscopy, of a remarkable consequence of the spin-orbit
interaction for holes confined in the molecular states of coupled quantum dots.
As the thickness of the barrier separating two coupled quantum dots is
increased, the molecular ground state changes character from a bonding orbital
to an antibonding orbital. This result is counterintuitive, and antibonding
molecular ground states are never observed in natural diatomic molecules. We
explain the origin of the reversal using a four band k.p model that has been
validated by numerical calculations that account for strain. The discovery of
antibonding molecular ground states provides new opportunities for the design
of artificially structured materials with complex molecular properties that
cannot be achieved in natural systems.


title:
Nuclear Structure and the Search for Collective Enhancement of
  P,T-Violation

abstract:
  The discovery of the atomic electric dipole moment (EDM) would reveal the
simultaneous violation of parity (P) and time-reversal (T) invariance. The EDM
can be induced by T-odd forces between the nucleus and atomic electrons. As the
nuclear dipole moment is screened according to the Schiff theorem, the
appropriate nuclear operator is the Schiff moment that may exist in nuclei
under PT-violation. We briefly review the current experimental situation and
discuss more in detail the ideas concerning possible collective mechanisms for
the enhancement of the nuclear Schiff moment. The most promising directions are
related to the coexistence of octupole and quadrupole collective modes, either
in the form of static deformation or as soft vibrational excitations. The
search for enhancement is important for widening the pool of nuclei as
candidates for the atomic EDM as well as for development of nuclear many-body
theory beyond standard mean-field and random phase approximations.


title:
Further Comments on Realization of Riemann Hypothesis via Coupling
  Constant Spectrum

abstract:
  We invoke Carlson's theorem to justify and to confirm the results previously
obtained on the validity of Riemann Hypothesis via the coupling constant
spectrum of the zero energy S-wave Jost function a la N. N. Khuri, for the
real, repulsive inverse-square potential in non-relativistic quantum mechanics
in 3 dimensions.


title: Geometry of depolarizing channels

abstract:
  Depolarizing maps acting on an N dimensional system are completely positive
maps resulting into compression of the Bloch ball along the different
polarization directions. In the qubit case these maps are a convex sum of four
extremal maps and form a simplex in the space of compression coefficients along
the three polarization directions. We calculate the compression domain for
three and four level systems. For a three level system the region has curved
surfaces, but it is a simplex for a four level system. We conjecture that it is
a simplex in the case of 2^n level systems.


title: Unfolding a Codimension-Two, Discontinuous, Andronov-Hopf Bifurcation

abstract:
  We present an unfolding of the codimension-two scenario of the simultaneous
occurrence of a discontinuous bifurcation and an Andronov-Hopf bifurcation in a
piecewise-smooth, continuous system of autonomous ordinary differential
equations in the plane. We find the Hopf cycle undergoes a grazing bifurcation
that may be very shortly followed by a saddle-node bifurcation of the orbit. We
derive scaling laws for the bifurcation curves that emanate from the
codimension-two bifurcation.


title: Magnetic Component of Quark-Gluon Plasma

abstract:
  We describe recent developments of the "magnetic scenario" of sQGP. We show
that at $T=(0.8-1.3)T_c$ there is a dense plasma of monopoles, capable of
supporting metastable flux tubes. Their existence allows to quantitatively
explained the non-trivial $T$-dependence of the static $\bar Q Q$ potential
energy calculated on the lattice. By molecular dynamics simulation we derived
transport properties (shear viscosity and diffusion constant) and showed that
the best liquid is given by most symmetric plasma, with 50%-50% of electric and
magnetic charges. The results are close to those of the ``perfect liquid''
observed at RHIC.


title:
Size matters: performance declines if your pixels are too big or too
  small

abstract:
  We present a conceptual model that describes the effect of pixel size on
target acquisition. We demonstrate the use of our conceptual model by applying
it to predict and explain the results of an experiment to evaluate users'
performance in a target acquisition task involving three distinct display
sizes: standard desktop, small and large displays. The results indicate that
users are fastest on standard desktop displays, undershoots are the most common
error on small displays and overshoots are the most common error on large
displays. We propose heuristics to maintain usability when changing displays.
Finally, we contribute to the growing body of evidence that amplitude does
affect performance in a display-based pointing task.


title:
Teichm\"uller Structures and Dual Geometric Gibbs Type Measure Theory
  for Continuous Potentials

abstract:
  The Gibbs measure theory for smooth potentials is an old and beautiful
subject and has many important applications in modern dynamical systems. For
continuous potentials, it is impossible to have such a theory in general.
However, we develop a dual geometric Gibbs type measure theory for certain
continuous potentials in this paper following some ideas and techniques from
Teichm\"uller theory for Riemann surfaces. Furthermore, we prove that the space
of those continuous potentials has a Teichm\"uller structure. Moreover, this
Teichm\"uller structure is a complete structure and is the completion of the
space of smooth potentials under this Teichm\"uller structure. Thus our dual
geometric Gibbs type theory is the completion of the Gibbs measure theory for
smooth potentials from the dual geometric point of view.


title: A lower bound on web services composition

abstract:
  A web service is modeled here as a finite state machine. A composition
problem for web services is to decide if a given web service can be constructed
from a given set of web services; where the construction is understood as a
simulation of the specification by a fully asynchronous product of the given
services. We show an EXPTIME-lower bound for this problem, thus matching the
known upper bound. Our result also applies to richer models of web services,
such as the Roman model.


title:
Violation of action--reaction and self-forces induced by nonequilibrium
  fluctuations

abstract:
  We show that the extension of Casimir-like forces to fluctuating fluids
driven out of equilibrium can exhibit two interrelated phenomena forbidden at
equilibrium: self-forces can be induced on single asymmetric objects and the
action--reaction principle between two objects can be violated. These effects
originate in asymmetric restrictions imposed by the objects' boundaries on the
fluid's fluctuations. They are not ruled out by the second law of
thermodynamics since the fluid is in a nonequilibrium state. Considering a
simple reaction--diffusion model for the fluid, we explicitly calculate the
self-force induced on a deformed circle. We also show that the action--reaction
principle does not apply for the internal Casimir forces exerting between a
circle and a plate. Their sum, instead of vanishing, provides the self-force on
the circle-plate assembly.


title:
Dzyaloshinsky-Moriya Anisotropy in the Spin-1/2 Kagom\'e Compound
  ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$

abstract:
  We report the determination of the Dzyaloshinsky-Moriya interaction, the
dominant magnetic anisotropy term in the \kagome spin-1/2 compound {\herbert}.
Based on the analysis of the high-temperature electron spin resonance (ESR)
spectra, we find its main component $|D_z|=15(1)$ K to be perpendicular to the
\kagome planes. Through the temperature dependent ESR line-width we observe a
building up of nearest-neighbor spin-spin correlations below $\sim$150 K.


title:
Hydrodynamic Simulation of a nano-flare heated multi-strand solar
  atmospheric loop

abstract:
  There is a growing body of evidence that the plasma loops seen with current
instrumentation (SOHO, TRACE and Hinode) may consist of many sub-resolution
elements or strands. Thus, the overall plasma evolution we observe in these
features could be the cumulative result of numerous individual strands
undergoing sporadic heating. This paper presents a short (10^9 cm ~ 10 Mm)
``global loop'' as 125 individual strands where each strand is modelled
independently by a one-dimensional hydrodynamic simulation. The energy release
mechanism across the strands consists of localised, discrete heating events
(nano-flares). The strands are ``coupled'' together through the frequency
distribution of the total energy input to the loop which follows a power law
distribution with index alpha. The location and lifetime of each energy event
occurring is random. Although a typical strand can go through a series of
well-defined heating/cooling cycles, when the strands are combined, the overall
quasi-static emission measure weighted thermal profile for the global loop
reproduces a hot apex/cool base structure. Localised cool plasma blobs are seen
to travel along individual strands which could cause the loop to `disappear'
from coronal emission and appear in transition or chromospheric ones. As alpha
increases (from 0 to 2.29 to 3.29), more weight is given to the smallest
heating episodes. Consequently, the overall global loop apex temperature
increases while the variation of the temperature around that value decreases.
Any further increase in alpha saturates the loop apex temperature variations at
the current simulation resolution. The effect of increasing the number of
strands and the loop length as well as the implications of these results upon
possible future observing campaigns for TRACE and Hinode are discussed.


title: Partial Cross-Correlation of D-Sequences based CDMA System

abstract:
  Like other pseudorandom sequences, decimal sequences may be used in designing
a Code Division Multiple Access (CDMA) system. They appear to be ideally suited
for this since the cross-correlation of d-sequences taken over the LCM of their
periods is zero. But a practical system will not, in most likelihood, satisfy
the condition that the number of chips per bit is equal to the LCM for all
sequences that are assigned to different users. It is essential, therefore, to
determine the partial cross-correlation properties of d-sequences. This paper
has performed experiments on d-sequences and found that the partial
cross-correlation is less than for PN sequences, indicating that d-sequences
can be effective for use in CDMA.


title: Jets in strongly-coupled N = 4 super Yang-Mills theory

abstract:
  We study jets of massless particles in N=4 super Yang-Mills using the AdS/CFT
correspondence both at zero and finite temperature. We set up an initial state
corresponding to a highly energetic quark/anti-quark pair and follow its time
evolution into two jets. At finite temperature the jets stop after traveling a
finite distance, whereas at zero temperature they travel and spread forever. We
map out the corresponding baryon number charge density and identify the generic
late time behavior of the jets as well as features that depend crucially on the
initial conditions.


title: Diffuse TeV Emission at the Galactic Centre

abstract:
  The High-Energy Stereoscopic System (HESS) has detected intense diffuse TeV
emission correlated with the distribution of molecular gas along the galactic
ridge at the centre of our Galaxy. Earlier HESS observations of this region had
already revealed the presence of several point sources at these energies, one
of them (HESS J1745-290) coincident with the supermassive black hole
Sagittarius A*. It is still not entirely clear what the origin of the TeV
emission is, nor even whether it is due to hadronic or leptonic interactions.
It is reasonable to suppose, however, that at least for the diffuse emission,
the tight correlation of the intensity distribution with the molecular gas
indicates a pionic-decay process involving relativistic protons. In this paper,
we explore the possible source(s) of energetic hadrons at the galactic centre,
and their propagation through a turbulent medium. We conclude that though
Sagittarius A* itself may be the source of cosmic rays producing the emission
in HESS J1745-290, it cannot be responsible for the diffuse emission farther
out. A distribution of point sources, such as pulsar wind nebulae dispersed
along the galactic plane, similarly do not produce a TeV emission profile
consistent with the HESS map. We conclude that only a relativistic proton
distribution accelerated throughout the inter-cloud medium can account for the
TeV emission profile measured with HESS.


title:
Subellipticity of the $\bar\partial$-Neumann problem on a weakly
  $q$-pseudoconvex/concave domain

abstract:
  For a domain $D$ of $\mathbb{C}^n$ which is weakly $q$-pseudoconvex or
$q$-pseudoconcave we give a sufficient condition for subelliptic estimates for
the $\bar{\partial}$-Neumann problem. The paper extends to domains which are
not necessarily pseudoconvex, the results and the techniques of Catlin.
  MSC: 32D10, 32U05, 32V25


title: Spitzer-MIPS Observations of the eta Cha Young Association

abstract:
  We have mapped the eta Chamaeleontis young stellar association in the
far-infrared with the Multiband Imaging Photometer for Spitzer (MIPS) on the
Spitzer Space Telescope. All sixteen members within the map region were
detected at 24 um, along with five members at 70 um and two at 160 um. Ten
stars show far-infrared excess emission indicating the presence of
circumstellar disks; six of these have central clearings as evidenced by the
onset of excess emission at >5 um. No new infrared excess sources are
identified among the 113 2MASS field stars with 24 um photometry but not seen
as X-ray sources, indicating that membership lists derived from X-ray surveys
are reasonably complete. Circumstellar disks in the eta Cha association span
the range from 1e-1 to 1e-4 in their fractional infrared luminosity, with a
median Ldust /Lstar of 0.04. The presence of optically thick, optically thin,
and intermediate optical depth disks within the same stellar group, in
combination with the large fraction of disks with inner holes, indicates that
the Cha association represents a crucial stage in circumstellar disk evolution.


title: Time-dependent V-representability on lattice systems

abstract:
  We study the mapping between time-dependent densities and potentials for
noninteracting electronic systems on lattices. As discovered recently by Baer
[J. Chem. Phys. 128, 044103 (2008)], there exist well-behaved time-dependent
density functions on lattices which cannot be associated with any real
time-dependent potential. This breakdown of time-dependent V-representability
can be tracked down to problems with the continuity equation which arise from
discretization of the kinetic-energy operator. Examples are given for lattices
with two points and with N points, and implications for practical numerical
applications of time-dependent density-functional theory are discussed. In the
continuum limit, time-dependent noninteracting V-representability is restored.


title:
Field and Temperature Dependence of the Superfluid Density in
  LaO_{1-x}F_xFeAs Superconductors: A Muon Spin Relaxation Study

abstract:
  We present zero field and transverse field \muSR experiments on the recently
discovered electron doped Fe-based superconductor LaO_{1-x}F_xFeAs. The zero
field experiments on underdoped (x=0.075) and optimally doped (x=0.1) samples
rule out any static magnetic order above 1.6 K in these superconducting
samples. From transverse field experiments in the vortex phase we deduce the
temperature and field dependence of the superfluid density. Whereas the
temperature dependence is consistent with a weak coupling BCS s-wave or a dirty
d-wave gap function scenario, the field dependence strongly evidences
unconventional superconductivity. We obtain the in-plane penetration depth of
\lambda_{ab} (0) = 254(2)nm for LaO_{0.9}F_{0.1}FeAs and \lambda_{ab} (0) =
364(8)nm for LaO_{0.925}F_{0.075}FeAs. Further evidence for unconventional
superconductivity is provided by the ratio of T_c versus the superfluid
density, which is close to the Uemura line of hole doped high-T_c cuprates.


title: Differences in Impact Factor Across Fields and Over Time

abstract:
  The bibliometric measure impact factor is a leading indicator of journal
influence, and impact factors are routinely used in making decisions ranging
from selecting journal subscriptions to allocating research funding to deciding
tenure cases. Yet journal impact factors have increased gradually over time,
and moreover impact factors vary widely across academic disciplines. Here we
quantify inflation over time and differences across fields in impact factor
scores and determine the sources of these differences. We find that the average
number of citations in reference lists has increased gradually, and this is the
predominant factor responsible for the inflation of impact factor scores over
time. Field-specific variation in the fraction of citations to literature
indexed by Thomson Scientific's Journal Citation Reports is the single greatest
contributor to differences among the impact factors of journals in different
fields. The growth rate of the scientific literature as a whole, and
cross-field differences in net size and growth rate of individual fields, have
had very little influence on impact factor inflation or on cross-field
differences in impact factor.


title: Feedback Control and the Arrow of Time

abstract:
  The purpose of this paper is to highlight the central role that the time
asymmetry of stability plays in feedback control. We show that this provides a
new perspective on the use of doubly-infinite or semi-infinite time axes for
signal spaces in control theory. We then focus on the implication of this time
asymmetry in modeling uncertainty, regulation and robust control. We point out
that modeling uncertainty and the ease of control depend critically on the
direction of time. We also discuss the relationship of this control-based
time-arrow with the well known arrows of time in physics.


title: Current quark mass dependence of nucleon magnetic moments and radii

abstract:
  A calculation of the current-quark-mass-dependence of nucleon static
electromagnetic properties is necessary in order to use observational data as a
means to place constraints on the variation of Nature's fundamental parameters.
A Poincare' covariant Faddeev equation, which describes baryons as composites
of confined-quarks and -nonpointlike-diquarks, is used to calculate this
dependence The results indicate that, like observables dependent on the
nucleons' magnetic moments, quantities sensitive to their magnetic and charge
radii, such as the energy levels and transition frequencies in Hydrogen and
Deuterium, might also provide a tool with which to place limits on the allowed
variation in Nature's constants.

categories: nucl-th astro-ph hep-lat hep-ph physics.atom-ph


title: HD 203608, a quiet asteroseismic target in the old galactic disk

abstract:
  A short observing run with the spectrometer Harps at the ESO 3.6-m telescope
was conducted in order to continue exploring the asteroseismic properties of F
type stars. In fact, Doppler observations of F type on the main sequence are
demanding and remain currently limited to a single case (HD 49933). Comparison
with photometric results obtained with the CoRoT mission on similar stars will
be possible with an enhanced set of observations. We selected the 4th magnitude
F8V star HD 203608, in order to investigate the oscillating properties of a
low-metallicity star of the old galactic disk. A 5-night asteroseismic
observation program has been conducted in August 2006 with Harps. Spectra were
reduced with the on-line data reduction software provided by the instrument. A
new statistical approach has been developed for extracting the significant
peaks in the Fourier domain. The oscillation spectrum shows a significant
excess power in the frequency range [1.5, 3.0 mHz]. It exhibits a large spacing
about 120.4 $\mu$Hz at 2.5 mHz. Variations of the large spacing with frequency
are clearly identified, which require an adapted asymptotic development. The
modes identification is based on the unambiguous signature of 15 modes with
$\ell = 0$ and 1. This observation shows the potential diagnostic of
asteroseismic constraints. Including them in the stellar modeling enhances
significantly the precision on the physical parameters of \cible, resulting in
a much more precise position in the HR diagram. The age of the star is now
determined in the range $7.25\pm0.07$ Gyr.


title: The Capacity Of Two Way Relay Channel

abstract:
  This paper investigates the capacity of a wireless two way relay channel in
which two end nodes exchange information via a relay node. The capacity is
defined in the information-theoretic sense as the maximum information exchange
rate between the two end nodes. We give an upper bound of the capacity by
applying the cut-set theorem. We prove that this upper bound can be approached
in low SNR region using "separated" multiple access for uplinks from the end
nodes to the relay in which the data from the end nodes are individually
decoded at the relay; and network-coding broadcast for downlinks from the relay
to the end nodes in which the relay mixes the information from end nodes before
forwarding. We further prove that the capacity is approachable in high SNR
region using physical-layer network coding (PNC) multiple access for uplinks,
and network-coding broadcast for downlinks. From our proof and observations, we
conjecture that the upper bound may be achieved with PNC in all SNR regions.


title: Particle-like solutions to classical noncommutative gauge theory

abstract:
  We construct perturbative static solutions to the classical field equations
of noncommutative U(1) gauge theory for the three cases: a) space-time
noncommutativity, b) space-space noncommutativity and c) both a) and b). The
solutions tend to the Coulumb solution at spatial infinity and are valid for
intermediate values of the radial coordinate $r$. They yield a self-charge in a
sphere of radius $r$ centered about the origin which increases with decreasing
$r$ for case a), and decreases with decreasing $r$ for case b). For case a)
this may mean that the exact solution screens an infinite charge at the origin,
while for case b) it is plausible that the charge density is well behaved at
the origin, as happens in Born-Infeld electrodynamics. For both cases a) and b)
the self-energy in the intermediate region grows faster as $r$ tends to the
origin than that of the Coulumb solution. It then appears that the divergence
of the classical self-energy is more severe in the noncommutative theory than
it is in the corresponding commutative theory. We compute the lowest order
effects of these solutions on the hydrogen atom spectrum and use them to put
experimental bounds on the space-time and space-space noncommutative scales. We
find that cases a) and b) have different experimental signatures.


title:
GZK Horizons and the Recent Pierre Auger Result on the Anisotropy of
  Highest-energy Cosmic Ray Sources

abstract:
  Motivated by recent Pierre Auger result on the correlation of the
highest-energy cosmic rays with the nearby active galactic nuclei, we explore
possible ultrahigh energy cosmic ray (UHECR) source distributions and their
effects on GZK horizons. Effects on GZK horizons by local over-density of UHECR
sources are examined carefully with constraints on the degree of local
over-density inferred from the measured UHECR spectrum. We include the energy
calibration effect on the Pierre Auger data in our studies. We propose possible
local over-densities of UHECR sources which are testable in the future cosmic
ray astronomy.


title:
Mechanism of generation of the emission bands in the dynamic spectrum of
  the Crab pulsar

abstract:
  We show that the proportionately spaced emission bands in the dynamic
spectrum of the Crab pulsar (Hankins T. H. & Eilek J. A., 2007, ApJ, 670, 693)
fit the oscillations of the square of a Bessel function whose argument exceeds
its order. This function has already been encountered in the analysis of the
emission from a polarization current with a superluminal distribution pattern:
a current whose distribution pattern rotates (with an angular frequency
$\omega$) and oscillates (with a frequency $\Omega>\omega$ differing from an
integral multiple of $\omega$) at the same time (Ardavan H., Ardavan A. &
Singleton J., 2003, J Opt Soc Am A, 20, 2137). Using the results of our earlier
analysis, we find that the dependence on frequency of the spacing and width of
the observed emission bands can be quantitatively accounted for by an
appropriate choice of the value of the single free parameter $\Omega/\omega$.
In addition, the value of this parameter, thus implied by Hankins & Eilek's
data, places the last peak in the amplitude of the oscillating Bessel function
in question at a frequency ($\sim\Omega^3/\omega^2$) that agrees with the
position of the observed ultraviolet peak in the spectrum of the Crab pulsar.
We also show how the suppression of the emission bands by the interference of
the contributions from differring polarizations can account for the differences
in the time and frequency signatures of the interpulse and the main pulse in
the Crab pulsar. Finally, we put the emission bands in the context of the
observed continuum spectrum of the Crab pulsar by fitting this broadband
spectrum (over 16 orders of magnitude of frequency) with that generated by an
electric current with a superluminally rotating distribution pattern.


title: anti-K anti-K N molecule state in three-body calculation

abstract:
  A $\bar{K}\bar{K}N$ system with $I=1/2$ and $J^P=1/2^+$ is investigated with
non-relativistic three-body calculations by using effective $\bar{K}N$ and
$\bar K \bar K$ interactions. The present investigation suggests that a weakly
bound state for the $\bar{K}\bar{K}N$ system can be formed below the two-body
threshold of $\bar{K}$ and quasibound $\bar{K}N$ with a $40 \sim 60$ MeV decay
width of $\bar{K}\bar{K}N\to \pi Y\bar{K}$. This corresponds to an excited
$\Xi$ baryon with $J^P=1/2^+$ located around 1.9 GeV. Studying the wave
function of the $\bar{K}\bar{K}N$ system obtained in this formulation, we find
that the three-body bound system has a characteristic structure of $\bar K
N$+$\bar K$ cluster with spatial extent.


title: On the deconfining limit in (2+1)-dimensional Yang-Mills theory

abstract:
  We consider (2+1)-dimensional Yang-Mills theory on $S^1 \times S^1 \times
{\bf R}$ in the framework of a Hamiltonian approach developed by Karabali, Kim
and Nair. The deconfining limit in the theory can be discussed in terms of one
of the $S^1$ radii of the torus ($S^1 \times S^1$), while the other radius goes
to infinity. We find that the limit agrees with the previously known result for
a dynamical propagator mass of a gluon. We also make comparisons with numerical
data.


title:
Photometric Studies of New Southern SU UMa-type dwarf novae, FL
  Triangulum Australe and CTCV J0549-4921

abstract:
  We report time-resolved optical CCD photometry on newly discovered SU
UMa-type dwarf novae, FL TrA and CTCV J0549-4921. During the 2006 August
outburst, we detected superhumps with a period of 0.59897(11) days for FL TrA,
clarifying the SU UMa nature of the system. On the first night of our
observations on FL TrA, the object showed no superhumps. This implies that it
takes a few days for full development of superhumps. The superhump period
variation diagram of FL TrA was similar to that observed in some WZ Sge stars
and short period SU UMa-type stars. This indicates that the system is closely
related to WZ Sge stars and SU UMa stars having short orbital periods. For CTCV
J0549-4921, the candidates of the mean superhump period are 0.083249(10) days
and 0.084257(8) days, respectively. Due to a lack of the observations, we
cannot determine the true superhump period, but the latter period is favorable.
Using the ASAS-3 archive, it turned out that the system shows only four
outbursts over the past 6 years. The outburst amplitude of CTCV J0549-4921 was
relatively small, with about 4.5 mag. One possibility is that mass evaporation
may play a role during quiescence.


title: Minimum Disturbance Measurement without Post-Selection

abstract:
  We propose and demonstrate a linear optical device which deterministically
performs optimal quantum measurement or minimum disturbance measurement on a
single-photon polarization qubit with the help of an ancillary path qubit
introduced to the same photon. We show theoretically and experimentally that
this device satisfies the minimum disturbance measurement condition by
investigating the relation between the information gain (estimation fidelity)
and the state disturbance due to measurement (operation fidelity). Our
implementation of minimum disturbance measurement is postselection-free in the
sense that all detection events are counted toward evaluation of the estimation
fidelity and the operation fidelity, i.e., there is no need for coincidence
postselection of the detection events.


title:
Developing a Theoretical Framework for Optofluidic Device Designing for
  System Identification in Systems Biology: the EGFR Study Case

abstract:
  Identification of dynamics underlying biochemical pathways of interest in
oncology is a primary goal in current systems biology. Understanding structures
and interactions that govern the evolution of such systems is believed to be a
cornerstone in this research. Systems theory and systems identification theory
are primary resources for this task since they both provide a self consistent
framework for modelling and manipulating models of dynamical systems that are
best suited for the problem under investigation. We address herein the issue of
obtaining an informative dataset ZN to be used as starting point for
identification of EGFR pathway dynamics. In order to match experimental
identifiability criteria we propose a theoretical framework for input stimulus
design based on dynamical properties of the system under investigation. A
feasible optofluidic design has been designed on the basis of the spectral
properties of the driving inputs that maximize information content after the
theoretical studies.


title:
Computer simulation of model cohesive powders: Plastic consolidation,
  structural changes and elasticity under isotropic loads

abstract:
  The quasistatic behavior of a simple 2D model of a cohesive powder under
isotropic loads is investigated by Discrete Element simulations. The loose
packing states, as studied in a previous paper, undergo important structural
changes under growing confining pressure P, while solid fraction \Phi
irreversibly increases by large amounts. The system state goes through three
stages, with different forms of the plastic consolidation curve \Phi(P*), under
growing reduced pressure P* = Pa/F0, defined with adhesion force F0 and grain
diameter a. In the low-confinement regime (I), plastic compaction is
negligible, and the structure is influenced by the assembling process. The
following stage (regime II) is independent of initial conditions. The void
ratio varies linearly with log P, as described in the engineering literature.
In the last stage of compaction (III), a maximum solid fraction is approached,
and properties of cohesionless granular packs are retrieved. Under
consolidation, while the fractal range of density correlations decreases, force
patterns reorganize, and elastic moduli increase by a large factor. Plastic
deformation events correspond to very small changes in the network topology,
while the denser regions tend to move like rigid bodies. Elastic properties are
dominated by the bending of thin junctions in loose systems. For growing RR
those tend to reduce to particle chains, the folding of which, rather than
tensile ruptures, controls plastic compaction.


title: Optical solitons as quantum objects

abstract:
  The intensity of classical bright solitons propagating in linearly coupled
identical fibers can be distributed either in a stable symmetric state at
strong coupling or in a stable asymmetric state if the coupling is small
enough. In the first case, if the initial state is not the equilibrium state,
the intensity may switch periodically from fiber to fiber, while in the second
case the a-symmetrical state remains forever, with most of its energy in either
fiber. The latter situation makes a state of propagation with two exactly
reciprocal realizations. In the quantum case, such a situation does not exist
as an eigenstate because of the quantum tunneling between the two fibers. Such
a tunneling is a purely quantum phenomenon which does not not exist in the
classical theory. We estimate the rate of tunneling by quantizing a simplified
dynamics derived from the original Lagrangian equations with test functions.
This tunneling could be within reach of the experiments, particularly if the
quantum coherence of the soliton can be maintained over a sufficient amount of
time.


title:
A unified construction yielding precisely Hilbert and James sequences
  spaces

abstract:
  Following James' approach, we shall define the Banach space $J(e)$ for each
vector $e=(e_1,e_2,...,e_d) \in \Bbb{R}^d$ with $ e_1 \ne 0$.
  The construction immediately implies that J(1) coincides with the Hilbert
space $i_2$ and that $J(1;-1)$ coincides with the celebrated quasireflexive
James space $J$. The results of this paper show that, up to an isomorphism,
there are only the following two possibilities: (i) either $J(e)$ is isomorphic
to $l_2$, if $e_1+e_2+...+e_d\ne 0$ (ii) or $J(e)$ is isomorphic to $J$. Such a
dichotomy also holds for every separable Orlicz sequence space $l_M$.


title:
Retarded Interaction of Electromagnetic field and Symmetry Violation of
  Time Reversal in Non-linear Optics

abstract:
  Based on Document (1), by considering the retarded interaction of radiation
fields, the third order transition probabilities of stimulated radiations and
absorptions of light are calculated. The revised formulas of nonlinear
polarizations are provided. The results show that that the general processes of
non-linear optics violate time reversal symmetry. The phenomena of non-linear
optics violating time reversal symmetry just as sum frequency, double
frequency, different frequencies, double stable states, self-focusing and
self-defocusing, echo phenomena, as well as optical self-transparence and self
absorptions and so on are analyzed.


title:
Search for a Signal on QCD Critical Point in Central Nucleus-Nucleus
  Collisions

abstract:
  We discuss that the QCD critical point could appear in central collisions in
percolation cluster. We suggest using the nuclear transparency effect and the
one of the light nuclear production to identify the critical point.


title: Siegel modular forms mod p

abstract:
  We prove a vanishing theorem for one forms on the moduli stack of principally
polarized abelian varieties of genus g>1 with level structure N over fields of
characteristic p different from two. This is used to compute the Picard groups
of these stacks. As an application we obtain results one congruences between
integral Siegel modular forms.


title:
Cosmological Constraints from Hubble parameter $H(z)$ and SN Ia
  observations

abstract:
  In this paper, we use a set of observational $H(z)$ data (OHD) to constrain
the $\Lambda$CDM cosmology. This data set can be derived from the differential
ages of the passively evolving galaxies. Meanwhile, the $\mathcal
{A}$-parameter, which describes the Baryonic Acoustic Oscillation (BAO) peak,
and the newly measured value of the Cosmic Microwave Background (CMB) shift
parameter $\mathcal {R}$ are used to present combinational constraints on the
same cosmology. The combinational constraints favor an accelerating flat
universe while the flat $\Lambda$CDM cosmology is also analyzed in the same
way. We obtain a result compatible with that by many other independent
cosmological observations. We find that the observational $H(z)$ data set is a
complementarity to other cosmological probes.


title: Some applications of the Beta function

abstract: This short note deals with some applications of the Beta function


title: Resonances of low orders in the planetary system of HD37124

abstract:
  The full set of published radial velocity data (52 measurements from Keck +
58 ones from ELODIE + 17 ones from CORALIE) for the star HD37124 is analysed.
Two families of dynamically stable high-eccentricity orbital solutions for the
planetary system are found. In the first one, the outer planets c and d are
trapped in the 2/1 mean-motion resonance. The second family of solutions
corresponds to the 5/2 mean-motion resonance between these planets. In both
families, the planets are locked in (or close to) an apsidal corotation
resonance. In the case of the 2/1 MMR, it is an asymmetric apsidal corotation
(with the difference between the longitudes of periastra $\Delta\omega\sim
60^\circ$), whereas in the case of the 5/2 MMR it is a symmetric antialigned
one ($\Delta\omega = 180^\circ$).
  It remains also possible that the two outer planets are not trapped in an
orbital resonance. Then their orbital eccentricities should be relatively small
(less than, say, 0.15) and the ratio of their orbital periods is unlikely to
exceed $2.3-2.5$.


title: Liquid flow-focused by a gas: jetting, dripping and recirculation

abstract:
  The liquid cone-jet mode can be produced upon stimulation by a co-flowing gas
sheath. Most applications deal with the jet breakup, leading to either of two
droplet generation regimes: jetting and dripping. The cone-jet flow pattern is
explored by direct axisymmetric VOF numerical simulation; its evolution is
studied as the liquid flow-rate is increased around the jetting-dripping
transition. As observed in other focused flows such as electrospraying cones
upon steady thread emission, the flow displays a strong recirculating pattern
within the conical meniscus; it is shown to play a role on the stability of the
system, being a precursor to the onset of dripping. Close to the minimum liquid
flow rate for steady jetting, the recirculation cell penetrates into the feed
tube. Both the jet diameter and the size of the cell are accurately estimated
by a simple theoretical model. In addition, the transition from jetting to
dripping is numerically analyzed in detail in some illustrative cases, and
compared, to good agreement, with a set of experiments.


title:
Primordial fluctuations and non-Gaussianities in multi-field DBI
  inflation

abstract:
  We study Dirac-Born-Infeld (DBI) inflation models with multiple scalar
fields. We show that the adiabatic and entropy modes propagate with a common
effective sound speed and are thus amplified at the sound horizon crossing. In
the small sound speed limit, we find that the amplitude of the entropy modes is
much higher than that of the adiabatic modes. We show that this could strongly
affect the observable curvature power spectrum as well as the amplitude of
non-Gaussianities, although their shape remains as in the single-field DBI
case.


title:
The pecular magnetic field morphology of the white dwarf WD 1953-011:
  evidence for a large-scale magnetic flux tube?

abstract:
  We present and interpret new spectropolarimetric observations of the magnetic
white dwarf WD 1953-011. Circular polarization and intensity spectra of the
H$\alpha$ spectral line demonstrate the presence of two-component magnetic
field in the photosphere of this star. The geometry consists of a weak, large
scale component, and a strong, localized component. Analyzing the rotationally
modulated low-field component, we establish a rotation period $P_{rot} = 1.4480
\pm 0.0001$ days. Modeling the measured magnetic observables, we find that the
low-field component can be described by the superposition of a dipole and
quadrupole. According to the best-fit model, the inclination of the stellar
rotation axis with respect to the line of sight is $i \approx 20^\circ$, and
the angle between the rotation axis and the dipolar axis is $\beta \approx
10^\circ$. The dipole strength at the pole is about 180 kG, and the quadrupolar
strength is about 230 kG. These data suggest a fossil origin of the low-field
component. In contrast, the strong-field component exhibits a peculiar,
localized structure (``magnetic spot'') that confirms the conclusions of Maxted
and co-workers. The mean field modulus of the spot ($|B_{spot}| = 520 \pm 7$
kG) together with its variable longitudinal magnetic field having a maximum of
about +400 kG make it difficult to describe it naturally as a high-order
component of the star's global poloidal field. Instead, we suggest that the
observed strong-field region has a geometry similar to a magnetic flux tube.


title:
Can Supermassive Black Holes Form in Metal-Enriched High-Redshift
  Protogalaxies ?

abstract:
  Primordial gas in protogalactic dark matter (DM) halos with virial
temperatures Tvir > 10^4 K begins to cool and condense via atomic hydrogen.
Provided this gas is irradiated by a strong ultraviolet (UV) flux and remains
free of H2 and other molecules, it has been proposed that the halo with Tvir
~10^4 K may avoid fragmentation, and lead to the rapid formation of a
supermassive black hole (SMBH) as massive as M=10^5-10^6 Msun. This
``head--start'' would help explain the presence of SMBHs with inferred masses
of several x 10^9 Msun, powering the bright quasars discovered in the Sloan
Digital Sky Survey at redshift z>~6. However, high-redshift DM halos with
Tvir~10^4K are likely already enriched with at least trace amounts of metals
and dust produced by prior star-formation in their progenitors. Here we study
the thermal and chemical evolution of low-metallicity gas exposed to extremely
strong UV radiation fields. Our results, obtained in one-zone models, suggest
that gas fragmentation is inevitable above a critical metallicity, whose value
is between Zcr~3x10^{-4} Zsun (in the absence of dust) and as low as Zcr~ 5 x
10^{-6} Zsun (with a dust-to-gas mass ratio of about 0.01 Z/Zsun). We propose
that when the metallicity exceeds these critical values, dense clusters of
low--mass stars may form at the halo nucleus. Relatively massive stars in such
a cluster can then rapidly coalesce into a single more massive object, which
may produce an intermediate-mass BH remnant with a mass up to M <~10^2-10^3
Msun.


title: Interlaced processes on the circle

abstract:
  When two Markov operators commute, it suggests that we can couple two copies
of one of the corresponding processes. We explicitly construct a number of
couplings of this type for a commuting family of Markov processes on the set of
conjugacy classes of the unitary group, using a dynamical rule inspired by the
RSK algorithm. Our motivation for doing this is to develop a parallel
programme, on the circle, to some recently discovered connections in random
matrix theory between reflected and conditioned systems of particles on the
line. One of the Markov chains we consider gives rise to a family of Gibbs
measures on `bead configurations' on the infinite cylinder. We show that these
measures have determinantal structure and compute the corresponding space-time
correlation kernel.


title: Ruan's Conjecture on Singular symplectic flops

abstract:
  We prove that the orbifold quantum ring is preserved under singular
symplectic flops. Hence we verify Ruan's conjecture for this case.


title: Singular symplectic flops and Ruan cohomology

abstract:
  In this paper, we study the symplectic geometry of singular conifolds of the
finite group quotient $$ W_r=\{(x,y,z,t)|xy-z^{2r}+t^2=0 \}/\mu_r(a,-a,1,0),
r\geq 1, $$ which we call orbi-conifolds. The related orbifold symplectic
conifold transition and orbifold symplectic flops are constructed. Let $X$ and
$Y$ be two symplectic orbifolds connected by such a flop. We study orbifold
Gromov-Witten invariants of exceptional classes on $X$ and $Y$ and show that
they have isomorphic Ruan cohomologies. Hence, we verify a conjecture of Ruan.


title:
A density functional theory for symmetric radical cations from bonding
  to dissociation

abstract:
  It is known for quite some time that approximate density functional (ADF)
theories fail disastrously when describing the dis-sociative symmetric radical
cations R2+. Considering this dissociation limit, previous work has shown that
Hartree-Fock (HF) theory favors the R+1--R0 charge distribution while DF
approximations favor the R+0.5 -- R+0.5. Yet, general quantum mechanical
principles indicate that both these (as well as all intermediate) average
charge distributions are asymptotically energy degenerate. Thus HF and ADF
theories mistakenly break the symmetry but in a contradicting way. In this
letter we show how to construct system-dependent long-range corrected (LC)
density functionals that can successfully treat this class of molecules,
avoiding the spurious symmetry breaking. Examples and comparisons to
experimental data is given for R=H, He and Ne and it is shown that the new LC
theory improves considerably the theoretical description of the R2+ bond
properties, the long range form of the asymptotic potential curve as well as
the atomic polarizability. The broader impact of this finding is discussed as
well and it is argued that the widespread semi-empirical approach which
advocates treating the LC parameter as a system-independent parameter is in
fact inappropriate under general circumstances.


title: The relativity of inertia and reality of nothing

abstract:
  We first see that the inertia of Newtonian mechanics is absolute and
troublesome. General relativity can be viewed as Einstein's attempt to remedy,
by making inertia relative, to matter---perhaps imperfectly though, as at least
a couple of freedom degrees separate inertia from matter in his theory. We
consider ways the relationist (for whom it is of course unwelcome) can try to
overcome such undetermination, dismissing it as physically meaningless,
especially by insisting on the right transformation properties.


title: Elastic proton-deuteron scattering at intermediate energies

abstract:
  Observables in elastic proton-deuteron scattering are sensitive probes of the
nucleon-nucleon interaction and three-nucleon force effects. The present
experimental data base for this reaction is large, but contains a large
discrepancy between data sets for the differential cross section taken at 135
MeV/nucleon by two experimental research groups. This paper reviews the
background of this problem and presents new data taken at KVI. Differential
cross sections and analyzing powers for the $^{2}{\rm H}(\vec p,d){p}$ and
${\rm H}(\vec d,d){p}$ reactions at 135 MeV/nucleon and 65 MeV/nucleon,
respectively, have been measured. The data differ significantly from previous
measurements and consistently follow the energy dependence as expected from an
interpolation of published data taken over a large range at intermediate
energies.


title: Fano-Type Resonance of Waves in Periodic Slabs

abstract:
  We investigate Fano-type anomalous transmission of energy of plane waves
across lossless slab scatterers with periodic structure in the presence of
non-robust guided modes. Our approach is based on rigorous analytic
perturbation of the scattering problem near a guided mode and applies to very
general structures, continuous and discrete.


title:
Energy distributions and effective temperatures in the packing of
  elastic sheets

abstract:
  The packing of elastic sheets is investigated in a quasi two-dimensional
experimental setup: a sheet is pulled through a rigid hole acting as a
container, so that its configuration is mostly prescribed by the cross-section
of the sheet in the plane of the hole. The characterisation of the packed
configuration is made possible by using refined image analysis. The geometrical
properties and energies of the branches forming the cross-section are broadly
distributed. We find distributions of energy with exponential tails. This setup
naturally divides the system into two sub-systems: in contact with the
container and within the bulk. While the geometrical properties of the
sub-systems differ, their energy distributions are identical, indicating
'thermal' homogeneity and allowing the definition of effective temperatures
from the characteristic scales of the energy distributions.


title: Derived Categories and Birational Geometry

abstract: A survey article for AMS Summer Institute at Seattle in 2005.


title: Finite generation of a canonical ring

abstract:
  The purpose of this note is to review an algebraic proof of the finite
generation theorem due to Birkar-Cascini-Hacon-McKernan whose method is based
on the Minimal Model Program. A survey article for Current Development in
Mathematics 2007.


title:
Bayesian computation for statistical models with intractable normalizing
  constants

abstract:
  This paper deals with some computational aspects in the Bayesian analysis of
statistical models with intractable normalizing constants. In the presence of
intractable normalizing constants in the likelihood function, traditional MCMC
methods cannot be applied. We propose an approach to sample from such posterior
distributions. The method can be thought as a Bayesian version of the MCMC-MLE
approach of Geyer and Thompson (1992). To the best of our knowledge, this is
the first general and asymptotically consistent Monte Carlo method for such
problems. We illustrate the method with examples from image segmentation and
social network modeling. We study as well the asymptotic behavior of the
algorithm and obtain a strong law of large numbers for empirical averages.


abstract:
  Thermodynamics of quasianti-Hermitian quaternionic systems with constant
number of particles in equilibrium is studied. A toy model is introduced and
the physically relevant quantities are derived. The energy fluctuation which
shows that for large N the relative r.m.s fluctuation in the values of E is
quite negligible is derived. The negative temperature for such systems is also
studied. Finally a physical example is discussed and physical explanations in
the context of quantum physics are given.


title: Discriminating multi-partite entangled states

abstract:
  The variety of multi-partite entangled states enables numerous applications
in novel quantum information tasks. In order to compare the suitability of
different states from a theoretical point of view classifications have been
introduced. Accordingly, here we derive criteria and demonstrate how to
experimentally discriminate an observed state against the ones of certain other
classes of multi-partite entangled states. Our method, originating in Bell
inequalities, adds an important tool for the characterization of multi-party
entanglement.


title:
Leveraging Coherent Distributed Space-Time Codes for Noncoherent
  Communication in Relay Networks via Training

abstract:
  For point to point multiple input multiple output systems,
Dayal-Brehler-Varanasi have proved that training codes achieve the same
diversity order as that of the underlying coherent space time block code (STBC)
if a simple minimum mean squared error estimate of the channel formed using the
training part is employed for coherent detection of the underlying STBC. In
this letter, a similar strategy involving a combination of training, channel
estimation and detection in conjunction with existing coherent distributed
STBCs is proposed for noncoherent communication in AF relay networks.
Simulation results show that the proposed simple strategy outperforms
distributed differential space-time coding for AF relay networks. Finally, the
proposed strategy is extended to asynchronous relay networks using orthogonal
frequency division multiplexing.


title: A Lost Theorem: Definite Integrals in Asymptotic Setting

abstract:
  We present a simple yet rigorous theory of integration that is based on two
axioms rather than on a construction involving Riemann sums. With several
examples we demonstrate how to set up integrals in applications of calculus
without using Riemann sums. In our axiomatic approach even the proof of the
existence of the definite integral (which does use Riemann sums) becomes
slightly more elegant than the conventional one. We also discuss an interesting
connection between our approach and the history of calculus. The article is
written for readers who teach calculus and its applications. It might be
accessible to students under a teacher's supervision and suitable for senior
projects on calculus, real analysis, or history of mathematics.


title: Loop Quantization of Vacuum Bianchi I Cosmology

abstract:
  We analyze the loop quantization of the family of vacuum Bianchi I
spacetimes, a gravitational system whose classical solutions describe
homogeneous anisotropic cosmologies. We rigorously construct the operator that
represents the Hamiltonian constraint, showing that the states of zero volume
completely decouple from the rest of quantum states. This fact ensures that the
classical cosmological singularity is resolved in the quantum theory. In
addition, this allows us to adopt an equivalent quantum description in terms of
a well defined densitized Hamiltonian constraint. This latter constraint can be
regarded in a certain sense as a difference evolution equation in an internal
time provided by one of the triad components, which is polymerically quantized.
Generically, this evolution equation is a relation between the projection of
the quantum states in three different sections of constant internal time.
Nevertheless, around the initial singularity the equation involves only the two
closest sections with the same orientation of the triad. This has a double
effect: on the one hand, physical states are determined just by the data on one
section, on the other hand, the evolution defined in this way never crosses the
singularity, without the need of any special boundary condition. Finally, we
provide these physical states with a Hilbert structure, completing the
quantization.


title: Wires with Quantum Memory

abstract:
  We show that quantum particles constrained to move along curves undergoing
cyclic deformations acquire, in general, geometric phases. We treat explicitly
an example, involving particular deformations of a circle, and ponder on
potential applications.


title: Maximally entangling tripartite protocols for Josephson phase qubits

abstract:
  We introduce a suit of simple entangling protocols for generating tripartite
GHZ and W states in systems with anisotropic exchange interaction
g(XX+YY)+g'ZZ. An interesting example is provided by macroscopic entanglement
in Josephson phase qubits with capacitive (g'=0) and inductive (0<|g'/g|<0.1)
couplings.


title: On the performance of approximate equilibria in congestion games

abstract:
  We study the performance of approximate Nash equilibria for linear congestion
games. We consider how much the price of anarchy worsens and how much the price
of stability improves as a function of the approximation factor $\epsilon$. We
give (almost) tight upper and lower bounds for both the price of anarchy and
the price of stability for atomic and non-atomic congestion games. Our results
not only encompass and generalize the existing results of exact equilibria to
$\epsilon$-Nash equilibria, but they also provide a unified approach which
reveals the common threads of the atomic and non-atomic price of anarchy
results. By expanding the spectrum, we also cast the existing results in a new
light. For example, the Pigou network, which gives tight results for exact Nash
equilibria of selfish routing, remains tight for the price of stability of
$\epsilon$-Nash equilibria but not for the price of anarchy.


title: Shear viscosity of CFT plasma at finite coupling

abstract:
  We present evidence for the universality of the shear viscosity of conformal
gauge theory plasmas beyond infinite coupling. We comment of subtleties of
computing the shear viscosity in effective models of gauge/gravity
correspondence rather than in string theory.


title:
On the problem of synchronization of identical dynamical systems: The
  Huygens's clocks

abstract:
  In 1665, Christiaan Huygens reported the observation of the synchronization
of two pendulum clocks hanged on the wall of his workshop. After
synchronization, the clocks swung exactly in the same frequency and $180^{o}$
out of phase -- anti-phase synchronization. Here, we propose and analyze a new
interaction mechanism between oscillators leading to exact anti-phase and
in-phase synchronization of pendulum clocks, and we determine a sufficient
condition for the existence of an exact anti-phase synchronization state. We
show that exact anti-phase and in-phase synchronization states can coexist in
phase space, and the periods of the synchronized states are different from the
eigen-periods of the individual oscillators. We analyze the robustness of the
system when the parameters of the individual pendulum clocks are varied, and we
show numerically that exact anti-phase and in-phase synchronization states
exist in systems of coupled oscillators with different parameters.


title: Hartman-Mycielski functor of non-metrizable compacta

abstract:
  We investigate some topological properties of a normal functor $H$ introduced
earlier by Radul which is a certain functorial compactification of the
Hartman-Mycielski construction $HM$. We show that $H$ is open and find the
condition when $HX$ is an absolute retract homeomorphic to the Tychonov cube.


title:
The Arf-Kervaire invariant of framed manifolds as an obstruction to
  embeddability

abstract:
  We define a quadratic form which gives an obstruction to embedding $N^{4k+2}
\subset \R^{6k+4}$ of a smooth highly connected manifold into Euclidean space,
with sufficiently many nondegenerate sections of the normal bundle. As the main
corollary we prove that no 14-connected (resp. 30-connected) stably
parallelizable manifold $N^{30}$ (resp. $N^{62}$) with Arf-Kervaire invariant
one is smoothly embeddable into $\R^{36}$ (resp. $\R^{83}$).


title: Bulk Universality for Unitary Matrix Models

abstract:
  We give a proof of universality in the bulk of spectrum of unitary matrix
models, assuming that the potential is globally $C^{2}$ and locally $C^{3}$
function. The proof is based on the determinant formulas for correlation
functions in terms of polynomials orthogonal on the unit circle. We do not use
asymptotics of orthogonal polynomials. We obtain the $sin$-kernel as a unique
solution of a certain non-linear integro-differential equation.


title: Analysis of comparative data with hierarchical autocorrelation

abstract:
  The asymptotic behavior of estimates and information criteria in linear
models are studied in the context of hierarchically correlated sampling units.
The work is motivated by biological data collected on species where
autocorrelation is based on the species' genealogical tree. Hierarchical
autocorrelation is also found in many other kinds of data, such as from
microarray experiments or human languages. Similar correlation also arises in
ANOVA models with nested effects. I show that the best linear unbiased
estimators are almost surely convergent but may not be consistent for some
parameters such as the intercept and lineage effects, in the context of
Brownian motion evolution on the genealogical tree. For the purpose of model
selection I show that the usual BIC does not provide an appropriate
approximation to the posterior probability of a model. To correct for this, an
effective sample size is introduced for parameters that are inconsistently
estimated. For biological studies, this work implies that tree-aware sampling
design is desirable; adding more sampling units may not help ancestral
reconstruction and only strong lineage effects may be detected with high power.


title: NSR Superstring Measures Revisited

abstract:
  Review of remarkable progress in evaluating of NSR superstring measures,
originated by E.D'Hoker and D.Phong. These recent results are presented in the
old-fashioned form, which allows to highlight the options that have been
overlooked in original considerations in late 1980's.


title: Preprojective algebras and cluster algebras

abstract:
  We use the representation theory of preprojective algebras to construct and
study certain cluster algebras related to semisimple algebraic groups.


title:
Cram\'{e}r asymptotics for finite time first passage probabilities of
  general L\'{e}vy processes

abstract:
  We derive the exact asymptotics of $P(\sup_{u\leq t}X(u) > x)$ if $x$ and $t$
tend to infinity with $x/t$ constant, for a L\'{e}vy process $X$ that admits
exponential moments. The proof is based on a renewal argument and a
two-dimensional renewal theorem of H\"{o}glund (1990).


title: From loops to trees by-passing Feynman's theorem

abstract:
  We derive a duality relation between one-loop integrals and phase-space
integrals emerging from them through single cuts. The duality relation is
realized by a modification of the customary +i0 prescription of the Feynman
propagators. The new prescription regularizing the propagators, which we write
in a Lorentz covariant form, compensates for the absence of multiple-cut
contributions that appear in the Feynman Tree Theorem. The duality relation can
be applied to generic one-loop quantities in any relativistic, local and
unitary field theories. %It is suitable for applications to the analytical
calculation of %one-loop scattering amplitudes, and to the numerical evaluation
of %cross-sections at next-to-leading order. We discuss in detail the duality
that relates one-loop and tree-level Green's functions. We comment on
applications to the analytical calculation of one-loop scattering amplitudes,
and to the numerical evaluation of cross-sections at next-to-leading order.


title: Optimization Approach for Detecting the Critical Data on a Database

abstract:
  Through purposeful introduction of malicious transactions (tracking
transactions) into randomly select nodes of a (database) graph, soiled and
clean segments are identified. Soiled and clean measures corresponding those
segments are then computed. These measures are used to repose the problem of
critical database elements detection as an optimization problem over the graph.
This method is universally applicable over a large class of graphs (including
directed, weighted, disconnected, cyclic) that occur in several contexts of
databases. A generalization argument is presented which extends the critical
data problem to abstract settings.


title: Plane Jacobian Conjecture for rational polynomials

abstract:
  A non-zero constant Jacobian polynomial maps $F=(P,Q)$ of $\mathbb{C}^2$ is
invertible if $P$ and $Q$ are rational polynomials.


title: Harold Jeffreys's Theory of Probability Revisited

abstract:
  Published exactly seventy years ago, Jeffreys's Theory of Probability (1939)
has had a unique impact on the Bayesian community and is now considered to be
one of the main classics in Bayesian Statistics as well as the initiator of the
objective Bayes school. In particular, its advances on the derivation of
noninformative priors as well as on the scaling of Bayes factors have had a
lasting impact on the field. However, the book reflects the characteristics of
the time, especially in terms of mathematical rigor. In this paper we point out
the fundamental aspects of this reference work, especially the thorough
coverage of testing problems and the construction of both estimation and
testing noninformative priors based on functional divergences. Our major aim
here is to help modern readers in navigating in this difficult text and in
concentrating on passages that are still relevant today.


title: Phase Transitions in Parallel Replication Process

abstract:
  The one-dimensional kinetic contact process with parallel update is
introduced and studied by Monte Carlo simulations. This process is proposed to
describe the plant population replication and epidemic disease spreading among
them. The phase diagram of the model features the line of the second order
transitions between absorbing and active phases. The numerical results for the
critical index beta demonstrate its continuous variation along the transition
line accompanied by the variations of the structural characteristics of
limiting steady states. We conjecture the non-universality of the critical
behavior of the model.


title:
Topological multicritical point in the Toric Code and 3D gauge Higgs
  Models

abstract:
  We report a new type of multicritical point that arises from competition
between the Higgs and confinement transitions in a Z_2 gauge system. The phase
diagram of the 3d gauge Higgs model has been obtained by Monte-Carlo simulation
on large (up to 60^3) lattices. We find the transition lines continue as
2nd-order until merging into a 1st-order line. These findings pose the question
of an effective field theory for a multicritical point involving noncommuting
order parameters. A similar phase diagram is predicted for the 2-dimensional
quantum toric code model with two external fields, h_z and h_x; this problem
can be mapped onto an anisotropic 3D gauge Higgs model.


title:
Model of the hippocampal formation explains the coexistence of grid
  cells and place cells

abstract:
  In this paper we explain the strikingly regular activity of the 'grid' cells
in rodent dorsal medial entorhinal cortex (dMEC) and the spatially localized
activity of the hippocampal place cells in CA3 and CA1 by assuming that the
hippocampal region is constructed to support an internal dynamical model of the
sensory information. The functioning of the different areas of the
hippocampal-entorhinal loop and their interaction are derived from a set of
information theoretical principles. We demonstrate through simple
transformations of the stimulus representations that the double form of space
representation (i.e. place field and regular grid tiling) can be seen as a
computational 'by-product' of the circuit. In contrast to other theoretical or
computational models we can also explain how place and grid activity may emerge
at the respective areas simultaneously. In accord with recent views, our
results point toward a close relation between the formation of episodic memory
and spatial navigation.


title:
Wave-breaking and generic singularities of nonlinear hyperbolic
  equations

abstract:
  Wave-breaking is studied analytically first and the results are compared with
accurate numerical simulations of 3D wave-breaking. We focus on the time
dependence of various quantities becoming singular at the onset of breaking.
The power laws derived from general arguments and the singular behavior of
solutions of nonlinear hyperbolic differential equations are in excellent
agreement with the numerical results. This shows the power of the analysis by
methods using generic concepts of nonlinear science.


title: The "Top Priority" at the LHC

abstract:
  The LHC will be a top-quark factory. With 80 million pairs of top quarks and
an additional 34 million single tops produced annually at the designed high
luminosity, the properties of this particle will be studied to a great
accuracy. The fact that the top quark is the heaviest elementary particle in
the Standard Model with a mass right at the electroweak scale makes it tempting
to contemplate its role in electroweak symmetry breaking, as well as its
potential as a window to unknown new physics at the TeV scale. We summarize the
expectations for top-quark physics at the LHC, and outline new physics
scenarios in which the top quark is crucially involved.


title:
Yang-Lee and Fisher zeros generalized on some far-from-equilibrium
  systems

abstract:
  A generalization of the Yang-Lee and Fisher zeros on far-from-equilibrium
systems coupled with two thermal baths is proposed. The Yang-Lee zeros were
obtained for minimal models which exhibit complicated behavior in the context
of the partition function zeros and provide an analitycal treatment. This type
of models may be considered as a simplest one and analogous to Ising model for
equilibrium. The obtained distributions of generalized Yang-Lee zeros show
nontrivial behavior for these simple models.


title: Critical magnetic field in AdS/CFT superconductor

abstract:
  We have studied a holographically dual description of superconductor in
(2+1)-dimensions in the presence of applied magnetic field, and observed that
there exists a critical value of magnetic field, below which a charged
condensate can form via a second order phase transition.


title:
Dynamics-Driven Evolution to Structural Heterogeneity in Complex
  Networks

abstract:
  The mutual influence of dynamics and structure is a central issue in complex
systems. In this paper we study by simulation slow evolution of network under
the feedback of a local-majority-rule opinion process. If performance-enhancing
local mutations have higher chances of getting integrated into its structure,
the system can evolve into a highly heterogeneous small-world with a global hub
(whose connectivity is proportional to the network size), strong local
connection correlations and power law-like degree distribution. Networks with
better dynamical performance are achieved if structural evolution occurs much
slower than the network dynamics. Structural heterogeneity of many biological
and social dynamical systems may also be driven by various dynamics-structure
coupling mechanisms.


title: Model independent determination of the sigma pole

abstract:
  The first part of this report reviews recent developments at the interface
between lattice work on QCD with light dynamical quarks, effective field theory
and low energy precision experiments. Then I discuss how dispersion theory can
be used to analyze the low energy structure of the $\pi\pi$ scattering
amplitude in a model independent manner. This leads to an exact formula for the
mass and width of the lowest few resonances, in terms of observable quantities.
As an application, I consider the pole position of the $\sigma$, paying
particular to error propagation in the numerical analysis. The report is based
on work done in collaboration with Irinel Caprini and Gilberto Colangelo.


title:
A Modified Y-M Action with Three Families of Fermionic Solitons and
  Perturbative Confinement

abstract:
  The dynamics of a four dimensional generally covariant modified SU(N)
Yang-Mills action, which depends on the complex structure of spacetime and not
its metric, is studied. A general solution of the complex structure
integrability conditions is found in the context of the G{2,2) Grassmannian
manifold, which admits a global SL(4,C) symmetry group. A convenient definition
of the physical energy and momentum permits the study of the vacuum and soliton
sectors. The model has a set of conformally SU(2,2) invariant vacua and a set
of Poincare invariant vacua. An algebraic integrability condition of the
complex structure classifies the solitonic surfaces into three classes
(families). The first class (spacetimes with two principal null directions)
contains the Kerr-Newman complex structure, which has fermionic (electron-like)
properties. That is the correct fermionic gyromagnetic ratio (g=2) and it
satisfies the correct electron equations of motion. The conjugate complex
structure determines the antisoliton, which has the same mass and opposite
charge. The fermionic solitons are differentiated from the complex structure
bosonic modes by the periodicity condition on compactified spacetime. The
non-periodicity of the found solitonic complex structures is proved. The
modification of the Yang-Mills action has an essential consequence to the
classical potential. It generates a linear static potential instead of the
Coulomb-like (1/r) potential of the ordinary Yang-Mills action. This linear
potential implies that for every pure geometric soliton there are N solitonic
gauge field excitations, which are perturbatively confined. The present model
advocates a solitonic unification scheme without supersymmetry and/or
superstrings.


title: Higher Green's functions for modular forms

abstract:
  Higher Green functions are real-valued functions of two variables on the
upper half plane which are bi-invariant under the action of a congruence
subgroup, have logarithmic singularity along the diagonal, but instead of the
usual equation $\Delta f=0$ we have equation $\Delta f = k(1-k) f$. Here $k$ is
a positive integer. Properties of these functions are related to the space of
modular forms of weight $2k$. In the case when there are no cusp forms of
weight $2k$ it was conjectured that the values of the Green function at points
of complex multiplication are algebraic multiples of logarithms of algebraic
numbers. We show that this conjecture can be proved in any particular case if
one constructs a family of elements of certain higher Chow groups on the power
of a family of elliptic curves. These families have to satisfy certain
properties. A different family of elements of Higher Chow groups is needed for
a different point of complex multiplication. We give an example of such
families, thereby proving the conjecture for the case when the group is
$PSL_2(\mathbf Z)$, $k=2$ and one of the arguments is $\sqrt{-1}$.


title:
$\pi N$ and $\pi\pi N$ Couplings of the $\Delta(1232)$ and its Chiral
  Partners

abstract:
  We investigate the interactions and chiral properties of the four
spin-$\thalf$-baryons : $N^-(D_{13})$, $N^+(P_{13})$, $\Delta^+(P_{33})$ and
$\Delta^-(D_{33})$ together with the nucleon. We construct the $SU(2)_R \times
SU(2)_L$ invariant interactions between the spin-$\half$ and -$\thalf$ baryons
with the aid of a new, specially developed spin and isospin projection
technique for these baryon fields, where the chiral invariant interactions
contain one- and two-pion couplings. We obtain simple relations for the
coupling constants of the one- and two-pion spin $\half-\thalf$ transitions
terms. The relation for the one-pion interactions reasonably agrees with the
experiments, which suggests that these spin-$\thalf$ baryons are chiral
partners.