title: Melting of trapped few particle systems

abstract:
  In small confined systems predictions for the melting point strongly depend
on the choice of quantity and on the way it is computed, even yielding
divergent and ambiguous results. We present a very simple quantity which allows
to control these problems -- the variance of the block averaged interparticle
distance fluctuations.


title:
Effect of excluded volume interactions on the interfacial properties of
  colloid-polymer mixtures

abstract:
  We report a numerical study of equilibrium phase-diagrams and interfacial
properties of bulk and confined colloid-polymer mixtures using grand canonical
Monte Carlo simulations. Colloidal particles are treated as hard spheres, while
the polymer chains are described as soft repulsive spheres. The
polymer-polymer, colloid-polymer, and wall-polymer interactions are described
by density-dependent potentials derived by Bolhuis and Louis [Macromolecules,
35 (2002), p.1860]. We compared our results with those of the
Asakura-Oosawa-Vrij model, that treats the polymers as ideal particles. We find
that the number of polymers needed to drive the demixing transition is larger
for the interacting polymers, and that the gas-liquid interfacial tension is
smaller. When the system is confined between two parallel hard plates, we find
capillary condensation. Compared with the AOV model, we find that the excluded
volume interactions between the polymers suppress capillary condensation. In
order to induce capillary condensation, smaller undersaturations and smaller
plate separations are needed in comparison with ideal polymers.


title: Goldbach Conjecture and First-Order Arithmetic

abstract:
  Using the concepts of Hyperbolic Classification of Natural Numbers, Essential
Regions and Goldbach Conjecture Function we prove that the existence of a proof
of the Goldbach Conjecture in First-Order Arithmetic would imply the existence
of another proof in a certain extension that would not be valid in all states
of time associated to natural numbers created by means of adequate dynamic
processes.


title: Hypercharge-Universal Topcolor

abstract:
  We propose and discuss the phenomenology of a Topcolor-assisted Technicolor
(TC2) model with a flavor-universal hypercharge sector. After discussing the
symmetry breaking pattern and low-energy effective Lagrangian, we examine
various experimental and theoretical constraints, finding that precision
electroweak measurements yield the strongest bounds on the model. We perform a
combined fit to all available $Z$-pole and LEP2 data and find that the goodness
of fit for hypercharge-universal topcolor is comparable to that of the Standard
Model. In contrast, TC2 models with a flavor non-universal hypercharge sectors
are markedly disfavored by the data.


title: Inversion method for content-based networks

abstract:
  In this paper, we generalize a recently introduced Expectation Maximization
(EM) method for graphs and apply it to content-based networks. The EM method
provides a classification of the nodes of a graph, and allows to infer
relations between the different classes. Content-based networks are ideal
models for graphs displaying any kind of community or/and multipartite
structure. We show both numerically and analytically that the generalized EM
method is able to recover the process that led to the generation of such
networks. We also investigate the conditions under which our generalized EM
method can recover the underlying contents-based structure in the presence of
randomness in the connections. Two entropies, Sq and Sc, are defined to measure
the quality of the node classification and to what extent the connectivity of a
given network is content-based. Sq and Sc are also useful in determining the
number of classes for which the classification is optimal.


title:
Characterization of graphene through anisotropy of constant-energy maps
  in angle-resolved photoemission

abstract:
  We show theoretically how constant-energy maps of the angle-resolved
photoemission intensity can be used to test wave function symmetry in graphene.
For monolayer graphene, we demonstrate that the observed anisotropy of ARPES
spectra is a manifestation of what has been recently branded as electronic
chirality. For bilayer graphene, we show that the anisotropy of the
constant-energy maps may be used to extract information about the magnitude and
sign of interlayer coupling parameters and about symmetry breaking inflicted on
a bilayer by the underlying substrate.


title:
Random walks in a random environment on a strip: a renormalization group
  approach

abstract:
  We present a real space renormalization group scheme for the problem of
random walks in a random environment on a strip, which includes one-dimensional
random walk in random environment with bounded non-nearest-neighbor jumps. We
show that the model renormalizes to an effective one-dimensional random walk
problem with nearest-neighbor jumps and conclude that Sinai scaling is valid in
the recurrent case, while in the sub-linear transient phase, the displacement
grows as a power of the time.


title: Chemical doping-induced gap opening and spin polarization in graphene

abstract:
  By using first principles calculations we report a chemical doping induced
gap in graphene. The structural and electronic properties of CrO$_3$
interacting with graphene layer are calculated using ab initio methods based on
the density functional theory. The CrO$_3$ acts as an electron acceptor
modifying the original electronic and magnetic properties of the graphene
surface through a chemical adsorption. The changes induced in the electronic
properties are strongly dependent of the CrO$_3$ adsorption site and for some
sites it is possible to open a gap in the electronic band structure. Spin
polarization effects are also predicted for some adsorption configurations.


title: Local Geometric Langlands Correspondence: the Spherical Case

abstract:
  A module over an affine Kac--Moody algebra g^ is called spherical if the
action of the Lie subalgebra g[[t]] on it integrates to an algebraic action of
the corresponding group G[[t]]. Consider the category of spherical g^-modules
of critical level. In this paper we prove that this category is equivalent to
the category of quasi-coherent sheaves on the ind-scheme of opers on the
punctured disc which are unramified as local systems. This result is a
categorical version of the well-known description of spherical vectors in
representations of groups over local non-archimedian fields. It may be viewed
as a special case of the local geometric Langlands correspondence proposed in
arXiv:math/0508382.


title:
Decelerating microdynamics can accelerate macrodynamics in the voter
  model

abstract:
  For the voter model, we study the effect of a memory-dependent transition
rate. We assume that the transition of a spin into the opposite state decreases
with the time it has been in its current state. Counter-intuitively, we find
that the time to reach a macroscopically ordered state can be accelerated by
slowing-down the microscopic dynamics in this way. This holds for different
network topologies, including fully-connected ones. We find that the ordering
dynamics is governed by two competing processes which either stabilize the
majority or the minority state. If the first one dominates, it accelerates the
ordering of the system. The conclusions of this Letter are not restricted to
the voter model, but remain valid to many other spin systems as well.


title: Landweber exact formal group laws and smooth cohomology theories

abstract:
  The main aim of this paper is the construction of a smooth (sometimes called
differential) extension \hat{MU} of the cohomology theory complex cobordism MU,
using cycles for \hat{MU}(M) which are essentially proper maps W\to M with a
fixed U(n)-structure and U(n)-connection on the (stable) normal bundle of W\to
M. Crucial is that this model allows the construction of a product structure
and of pushdown maps for this smooth extension of MU, which have all the
expected properties. Moreover, we show, using the Landweber exact functor
principle, that \hat{R}(M):=\hat{MU}(M)\otimes_{MU^*}R defines a multiplicative
smooth extension of R(M):=MU(M)\otimes_{MU^*}R whenever R is a Landweber exact
MU*-module. An example for this construction is a new way to define a
multiplicative smooth K-theory.


title: The rank of a quiver representation

abstract:
  We define a functor which gives the "global rank of a quiver representation"
and prove that it has nice properties which make it a generalization of the
rank of a linear map. We demonstrate how to construct other "rank functors" for
a quiver Q, which induce ring homomorphisms (called "rank functions") from the
representation ring of Q to Z. These rank functions give discrete numerical
invariants of quiver representations, useful for computing tensor product
multiplicities of representations and determining some structure of the
representation ring. We also show that in characteristic 0, rank functors
commute with the Schur operations on quiver representations, and the
homomorphisms induced by rank functors are lambda-ring homomorphisms.


title: Analysis of continuous strict local martingales via h-transforms

abstract:
  We study strict local martingales via h-transforms, a method which first
appeared in Delbaen-Schachermayer. We show that strict local martingales arise
whenever there is a consistent family of change of measures where the two
measures are not equivalent to one another. Several old and new strict local
martingales are identified. We treat examples of diffusions with various
boundary behavior, size-bias sampling of diffusion paths, and non-colliding
diffusions. A multidimensional generalization to conformal strict local
martingales is achieved through Kelvin transform. As curious examples of
non-standard behavior, we show by various examples that strict local
martingales do not behave uniformly when the function (x-K)^+ is applied to
them. Implications to the recent literature on financial bubbles are discussed.


title: Dielectronic recombination and stability of warm gas in AGN

abstract:
  Understanding the thermal equilibrium (stability) curve may offer insights
into the nature of the warm absorbers often found in active galactic nuclei.
Its shape is determined by factors like the spectrum of the ionizing continuum
and the chemical composition of the gas. We find that the stability curves
obtained under the same set of the above mentioned physical factors, but using
recently derived dielectronic recombination rates, give significantly different
results, especially in the regions corresponding to warm absorbers, leading to
different physical predictions. Using the current rates we find a larger
probability of having thermally stable warm absorber at $10^5 \kel$ than
previous predictions and also a greater possibility for its multiphase nature.
the results obtained with the current dielectronic recombination rate
coefficients are more reliable because the warm absorber models along the
stability curve have computed coefficient values, whereas previous calculations
relied on guessed averages for the same due to lack of available data.


title:
Evidence for a parity doublet Delta(1920)P_{33} and Delta(1940)D_{33}$
  from \gamma p\to p\pi^0\eta

abstract:
  Evidence is reported for the existence of a parity doublet of Delta
resonances with total angular momentum J=3/2 from photoproduction of the p pi^0
eta final state. The two parity partners Delta(1920)P_{33} and
Delta(1940)D_{33} make significant contributions to the reaction. Cascades of
resonances into Delta(1232) eta, N(1535) pi, and N a_0(980) are clearly
observed.


title:
The hydrogen-deficient knot of the `born again' planetary nebula Abell
  58 (V605 Aql)

abstract:
  We have analysed deep optical spectra of the `born-again' planetary nebula
Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent
a nova-like eruption in 1919. The electron temperature we derive for the
central knot varies widely depending on the diagnostic used. The [O III]
nebular-to-auroral transition ratio gives a temperature of 20800 K, while the
ratio of the [N II] nebular and auroral lines give Te=15200 K. The helium line
ratios 5876/4471 and 6678/4471 imply temperatures of 350 K and 550 K
respectively. Weakly temperature-sensitive O II recombination line ratios imply
similarly low electron temperatures. Abundances derived from recombination
lines are vastly higher than those found from collisionally excited lines, with
the abundance discrepancy factor (adf) for O2+ reaching 89 -- the second
highest known value after that found for the hydrogen deficient knots in Abell
30. The observed temperature diagnostics and abundances support the idea that,
like Abell 30, the knot of Abell 58 contains some very cold ionised material.
Although the central star is carbon-rich (C/O>1), the knot is found to be
oxygen-rich, a situation not predicted by the single-star `born again' theory
of its formation. We argue that the abundances in the ejecta observed in A 30
and A 58 have more in common with neon novae than with Sakurai's Object, which
is believed to have undergone a final helium flash. In particular, the C/O
ratio of less than unity and presence of substantial quantities of neon in the
ejecta of both Abell 30 and Abell 58 are not predicted by very late thermal
pulse models.


title: On Enumeration of Conjugacy Classes of Coxeter Elements

abstract:
  In this paper we study the equivalence relation on the set of acyclic
orientations of a graph Y that arises through source-to-sink conversions. This
source-to-sink conversion encodes, e.g. conjugation of Coxeter elements of a
Coxeter group. We give a direct proof of a recursion for the number of
equivalence classes of this relation for an arbitrary graph Y using edge
deletion and edge contraction of non-bridge edges. We conclude by showing how
this result may also be obtained through an evaluation of the Tutte polynomial
as T(Y,1,0), and we provide bijections to two other classes of acyclic
orientations that are known to be counted in the same way. A transversal of the
set of equivalence classes is given.


title: Transcriptional pulsing and consequent stochasticity in gene expression

abstract:
  Transcriptional pulsing has been observed in both prokaryotes and eukaryotes
and plays a crucial role in cell to cell variability of protein and mRNA
numbers. The issue is how the time constants associated with episodes of
transcriptional bursting impact cellular mRNA and protein distributions and
reciprocally, to what extent experimentally observed distributions can be
attributed to transcriptional pulsing. We address these questions by
investigating the exact time-dependent solution of the Master equation for a
transcriptional pulsing model of mRNA distributions. We find a plethora of
results: we show that, among others, bimodal and long-tailed (power law)
distributions occur in the steady state as the rate constants are varied over
biologically significant time scales. Since steady state distributions may not
be reached experimentally we present results for the time evolution of the
distributions. Because cellular behavior is essentially determined by proteins,
we investigate the effect of the different mRNA distributions on the
corresponding protein distributions. We delineate the regimes of rate constants
for which the protein distribution mimics the mRNA distribution and those for
which the protein distribution deviates significantly from the mRNA
distribution.


title: An Expanding Shell and Synchrotron Jet in RS Ophiuchi

abstract:
  We report high-resolution radio imaging of the recurrent nova RS Ophiuchi (RS
Oph) during the first month of the 2006 outburst, using the Very Long Baseline
Array (VLBA). Observations made on days 20.8 and 26.8 of the outburst show a
synchrotron-emitting partial shell that is much brighter to the east than to
the west. Assuming the broad component of the infrared lines corresponds to the
outermost part of the shell seen by the VLBA, the distance to the source is
$2.45\pm0.4 kpc$. The circular shape and spectral indices of the shell emission
challenge simple models for the radio structure immediately after the outburst.
The second epoch also shows an additional, resolved, synchrotron-emitting
component well to the east of the shell. Its inferred velocity is comparable to
the escape speed from the surface of a high-mass white dwarf. This component
was not seen in the first epoch. Its appearance may be related to the outflow
reaching the edge of the nebula created by the red giant wind, which had been
re-filling the void left by the last outburst in 1985. This eastern component
is likely related to the jets previously seen in this and other symbiotic
stars, and represents the earliest clear detection of such a jet, as well as
the best case yet for synchrotron emission from a white dwarf jet.


title: Optimal intertemporal risk allocation applied to insurance pricing

abstract:
  We present a general approach to the pricing of products in finance and
insurance in the multi-period setting. It is a combination of the utility
indifference pricing and optimal intertemporal risk allocation. We give a
characterization of the optimal intertemporal risk allocation by a first order
condition. Applying this result to the exponential utility function, we obtain
an essentially new type of premium calculation method for a popular type of
multi-period insurance contract. This method is simple and can be easily
implemented numerically. We see that the results of numerical calculations are
well coincident with the risk loading level determined by traditional
practices. The results also suggest a possible implied utility approach to
insurance pricing.


title: The Origin of Radio Scintillation In the Local Interstellar Medium

abstract:
  We study three quasar radio sources (B1257-326, B1519-273, and J1819+385)
that show large amplitude intraday and annual scintillation variability
produced by the Earth's motion relative to turbulent-scattering screens located
within a few parsecs of the Sun. We find that the lines of sight to these
sources pass through the edges of partially ionized warm interstellar clouds
where two or more clouds may interact. From the gas flow vectors of these
clouds, we find that the relative radial and transverse velocities of these
clouds are large and could generate the turbulence that is responsible for the
observed scintillation. For all three sight lines the flow velocities of nearby
warm local interstellar clouds are consistent with the fits to the transverse
flows of the radio scintillation signals.


title: A critique of general relativity

abstract:
  General relativity's successes and limitations are compared to those of
special relativity.


title:
Modeling homophily and stochastic equivalence in symmetric relational
  data

abstract:
  This article discusses a latent variable model for inference and prediction
of symmetric relational data.
  The model, based on the idea of the eigenvalue decomposition, represents the
relationship between two nodes as the weighted inner-product of node-specific
vectors of latent characteristics. This ``eigenmodel'' generalizes other
popular latent variable models, such as latent class and distance models: It is
shown mathematically that any latent class or distance model has a
representation as an eigenmodel, but not vice-versa. The practical implications
of this are examined in the context of three real datasets, for which the
eigenmodel has as good or better out-of-sample predictive performance than the
other two models.


title: A discrete variational identity on semi-direct sums of Lie algebras

abstract:
  The discrete variational identity under general bilinear forms on semi-direct
sums of Lie algebras is established. The constant $\gamma$ involved in the
variational identity is determined through the corresponding solution to the
stationary discrete zero curvature equation. An application of the resulting
variational identity to a class of semi-direct sums of Lie algebras in the
Volterra lattice case furnishes Hamiltonian structures for the associated
integrable couplings of the Volterra lattice hierarchy.

categories: nlin.SI math-ph math.MP nlin.PS physics.class-ph


title: On the Kert\'esz line: Thermodynamic versus Geometric Criticality

abstract:
  The critical behaviour of the Ising model in the absence of an external
magnetic field can be specified either through spontaneous symmetry breaking
(thermal criticality) or through cluster percolation (geometric criticality).
We extend this to finite external fields for the case of the Potts' model,
showing that a geometric analysis leads to the same first order/second order
structure as found in thermodynamic studies. We calculate the Kert\'esz line,
separating percolating and non-percolating regimes, both analytically and
numerically for the Potts model in presence of an external magnetic field.


title: Stein or Milnor fillability and cohomology

abstract:
  I have withdrawn the paper, after having incorporated it into the paper
arXiv:0712.3484. In the meantime I have discovered that one of the theorems
proved in the paper had already been proved by Durfee & Hain.


title: Junction Conditions in f(R) Theories of Gravity

abstract:
  Taking advantage of the conformal equivalence of f(R) theories of gravity
with General Relativity coupled to a scalar field we generalize the Israel
junction conditions for this class of theories by direct integration of the
field equations. We suggest a specific non-minimal coupling of matter to
gravity which opens the possibility of a new class of braneworld scenarios.


title: Projections, Entropy and Sumsets

abstract:
  In this paper we have shall generalize Shearer's entropy inequality and its
recent extensions by Madiman and Tetali, and shall apply projection
inequalities to deduce extensions of some of the inequalities concerning sums
of sets of integers proved recently by Gyarmati, Matolcsi and Ruzsa. We shall
also discuss projection and entropy inequalities and their connections.


title: Near-Infrared Mapping and Physical Properties of the Dwarf-Planet Ceres

abstract:
  We study the physical characteristics (shape, dimensions, spin axis
direction, albedo maps, mineralogy) of the dwarf-planet Ceres based on
high-angular resolution near-infrared observations. We analyze adaptive optics
J/H/K imaging observations of Ceres performed at Keck II Observatory in
September 2002 with an equivalent spatial resolution of ~50 km. The spectral
behavior of the main geological features present on Ceres is compared with
laboratory samples. Ceres' shape can be described by an oblate spheroid (a = b
= 479.7 +/- 2.3 km, c = 444.4 +/- 2.1 km) with EQJ2000.0 spin vector
coordinates RA = 288 +/- 5 deg. and DEC = +66 +/- 5 deg. Ceres sidereal period
is measured to be 9.0741 +/- 0.0001 h. We image surface features with diameters
in the 50-180 km range and an albedo contrast of ~6% with respect to the
average Ceres albedo. The spectral behavior of the brightest regions on Ceres
is consistent with phyllosilicates and carbonate compounds. Darker isolated
regions could be related to the presence of frost.


title: Estimating the trace-free Ricci tensor in Ricci flow

abstract:
  An important and natural question in the analysis of Ricci flow singularity
formation in dimensions four and above is as follows: What are the weakest
conditions that provide control of the norm of the Riemann curvature tensor? In
this short note, we show that on a compact manifold, the trace-free Ricci
tensor is controlled in a precise fashion by the other components of the
irreducible decomposition of the curvature tensor, without any hypotheses on
the initial data.


title:
Bounds on the Simplest Little Higgs Model Mass Spectrum Through Z
  Leptonic Decay

abstract:
  We derive the leptonic neutral current in the simplest little Higgs model and
compute the contribution of the model to the decay width $Z \to e^+e^-$. Using
the precision electroweak data we obtain a strong lower bound $f\geq 5.6$ TeV
at 95% C.L. on the characteristic energy scale of the model. It results in a
lower bound for the new gauge bosons $W^{\prime\pm}$ and $Z^{\prime}$ as being
$M_{W^{\prime\pm}}\geq 2.6$ TeV and $M_{Z^{\prime}}\geq 3.1$ TeV, respectively.
We also present the allowed values of the $k=f_1/f_2$ which is the parameter
relating the two vacuum expectation values of the scalar triplets in the model,
and the $\mu$ parameter of a quadratic term, involving the triplets, necessary
to provide an acceptable mass range for the standard Higgs boson.


title:
L^2 Castelnuovo-de Franchis, the cup product lemma, and filtered ends of
  Kaehler manifolds

abstract:
  Simple approaches to the proofs of the L^2 Castelnuovo-de Franchis theorem
and the cup product lemma which give new versions are developed. For example,
suppose u and v are two linearly independent closed holomorphic 1-forms on a
bounded geometry connected complete Kaehler manifold X with v in L^2. According
to a version of the L^2 Castelnuovo-de Franchis theorem obtained in this paper,
if u and v are pointwise linearly dependent, then there exists a surjective
proper holomorphic mapping of X onto a Riemann surface for which u and v are
pull-backs. Previous versions required both forms to be in L^2.


title: NMR Analog of Bell's Inequalities Violation Test

abstract:
  In this paper we present an analog of the Bell's inequalities violation test
for $N$ qubits to be performed in a nuclear magnetic resonance (NMR) quantum
computer. This can be used to simulate or predict results for different Bell's
inequalities tests, with distinct configurations and larger number of qubits.
To demonstrate our scheme, we implemented a simulation of the violation of
Clauser, Horne, Shimony and Holt (CHSH) inequality using a two qubit NMR system
and compared the results to those of a photon experiment. The experimental
results are well described by Quantum Mechanics theory and a Local Realistic
Hidden Variables model which was specially developed for NMR. That is why we
refer to this experiment as a {\it simulation} of the Bell's inequality
violation. Our result shows explicitly how both theories can be compatible to
each other due the detection loophole. In the last part of this work we discuss
the possibility of testing fundamental features of quantum mechanics using NMR
with highly polarized spins, where a strong discrepancy between quantum
mechanics and hidden variables models can be expected.


title: Toward a Unit Distance Embedding for the Heawood graph

abstract:
  The unit distance embeddability of a graph, like planarity, involves a mix of
constraints that are combinatorial and geometric. We construct a unit distance
embedding for $H-e$ in the hope that it will lead to an embedding for $H$. We
then investigate analytical methods for a general decision procedure for
testing unit distance embeddability.


title: Parsec-scale Magnetic-Field Structures in HEAO-1 BL Lacs

abstract:
  We present very long baseline interferometry polarization images of an X-ray
selected sample of BL Lacertae objects belonging to the first High Energy
Astronomy Observatory (HEAO-1) and the ROSAT-Green Bank (RGB) surveys. These
are primarily high-energy-peaked BL Lacs (HBLs) and exhibit core-jet radio
morphologies on pc-scales. They show moderately polarized jet components,
similar to those of low-energy-peaked BL Lacs (LBLs). The fractional
polarization in the unresolved cores of the HBLs is, on average, lower than in
the LBLs, while the fractional polarizations in the pc-scale jets of HBLs and
LBLs are comparable. However a difference is observed in the orientation of the
inferred jet magnetic fields -- while LBL jets are well-known to preferentially
exhibit transverse magnetic fields, the HBL jets tend to display longitudinal
magnetic fields. Although a `spine-sheath' jet velocity structure, along with
larger viewing angles for HBLs could produce the observed magnetic field
configuration, differences in other properties of LBLs and HBLs, such as their
total radio power, cannot be fully reconciled with the different-angle scenario
alone. Instead it appears that LBLs and HBLs differ intrinsically, perhaps in
the spin rates of their central black holes.


title: Entropy of String States at fixed Mass and Size

abstract:
  We provide formulas for the entropy of free-string states depending on their
mass, charges and size, both in bosonic and superstring theory (IIA or IIB). We
properly define these quantities in full-fledged string theory. We then
investigate the corrections to the entropy due to self-interactions of the
string for states with fixed mass, charge and size, both for BPS and non-BPS
configurations. Again, the analysis is performed using string theory
techniques.


title: On rigidity and the isomorphism problem for tree braid groups

abstract:
  We solve the isomorphism problem for braid groups on trees with $n = 4$ or 5
strands. We do so in three main steps, each of which is interesting in its own
right. First, we establish some tools and terminology for dealing with
computations using the cohomology of tree braid groups, couching our discussion
in the language of differential forms. Second, we show that, given a tree braid
group $B_nT$ on $n = 4$ or 5 strands, $H^*(B_nT)$ is an exterior face algebra.
Finally, we prove that one may reconstruct the tree $T$ from a tree braid group
$B_nT$ for $n = 4$ or 5. Among other corollaries, this third step shows that,
when $n = 4$ or 5, tree braid groups $B_nT$ and trees $T$ (up to homeomorphism)
are in bijective correspondence. That such a bijection exists is not true for
higher dimensional spaces, and is an artifact of the 1-dimensionality of trees.
We end by stating the results for right-angled Artin groups corresponding to
the main theorems, some of which do not yet appear in the literature.


title: Joint Source-Channel Codes for MIMO Block Fading Channels

abstract:
  We consider transmission of a continuous amplitude source over an L-block
Rayleigh fading $M_t \times M_r$ MIMO channel when the channel state
information is only available at the receiver. Since the channel is not
ergodic, Shannon's source-channel separation theorem becomes obsolete and the
optimal performance requires a joint source -channel approach. Our goal is to
minimize the expected end-to-end distortion, particularly in the high SNR
regime. The figure of merit is the distortion exponent, defined as the
exponential decay rate of the expected distortion with increasing SNR. We
provide an upper bound and lower bounds for the distortion exponent with
respect to the bandwidth ratio among the channel and source bandwidths. For the
lower bounds, we analyze three different strategies based on layered source
coding concatenated with progressive, superposition or hybrid digital/analog
transmission. In each case, by adjusting the system parameters we optimize the
distortion exponent as a function of the bandwidth ratio. We prove that the
distortion exponent upper bound can be achieved when the channel has only one
degree of freedom, that is L=1, and $\min\{M_t,M_r\}=1$. When we have more
degrees of freedom, our achievable distortion exponents meet the upper bound
for only certain ranges of the bandwidth ratio. We demonstrate that our
results, which were derived for a complex Gaussian source, can be extended to
more general source distributions as well.


title:
The formation of ultra-compact dwarf galaxies and nucleated dwarf
  galaxies

abstract:
  Ultra compact dwarf galaxies (UCDs) have similar properties as massive
globular clusters or the nuclei of nucleated galaxies. Recent observations
suggesting a high dark matter content and a steep spatial distribution within
groups and clusters provide new clues as to their origins. We perform
high-resolution N-body / smoothed particle hydrodynamics simulations designed
to elucidate two possible formation mechanisms for these systems: the merging
of globular clusters in the centre of a dark matter halo, or the massively
stripped remnant of a nucleated galaxy. Both models produce density profiles as
well as the half light radii that can fit the observational constraints.
However, we show that the first scenario results to UCDs that are underluminous
and contain no dark matter. This is because the sinking process ejects most of
the dark matter particles from the halo centre. Stripped nuclei give a more
promising explanation, especially if the nuclei form via the sinking of gas,
funneled down inner galactic bars, since this process enhances the central dark
matter content. Even when the entire disk is tidally stripped away, the nucleus
stays intact and can remain dark matter dominated even after severe stripping.
Total galaxy disruption beyond the nuclei only occurs on certain orbits and
depends on the amount of dissipation during nuclei formation. By comparing the
total disruption of CDM subhaloes in a cluster potential we demonstrate that
this model also leads to the observed spatial distribution of UCDs which can be
tested in more detail with larger data sets.


title: Implications for the Origin of GRB 070201 from LIGO Observations

abstract:
  We analyzed the available LIGO data coincident with GRB 070201, a short
duration hard spectrum gamma-ray burst whose electromagnetically determined sky
position is coincident with the spiral arms of the Andromeda galaxy (M31).
Possible progenitors of such short hard GRBs include mergers of neutron stars
or a neutron star and black hole, or soft gamma-ray repeater (SGR) flares.
These events can be accompanied by gravitational-wave emission. No plausible
gravitational wave candidates were found within a 180 s long window around the
time of GRB 070201. This result implies that a compact binary progenitor of GRB
070201, with masses in the range 1 M_sun < m_1 < 3 M_sun and 1 M_sun < m_2 < 40
M_sun, located in M31 is excluded at >99% confidence. Indeed, if GRB 070201
were caused by a binary neutron star merger, we find that D < 3.5 Mpc is
excluded, assuming random inclination, at 90% confidence. The result also
implies that an unmodeled gravitational wave burst from GRB 070201 most
probably emitted less than 4.4 x 10^(-4) M_sun c^2 (7.9 x 10^(50) ergs) in any
100 ms long period within the signal region if the source was in M31 and
radiated isotropically at the same frequency as LIGO's peak sensitivity (f ~
150 Hz). This upper limit does not exclude current models of SGRs at the M31
distance.


title: Hypervelocity A & B Stars should be slow rotators

abstract:
  The most commonly accepted explanation for the origin of hypervelocity stars
in the halo of the Milky Way is that they are the result of tidal disruption of
binaries by the massive black hole at the center of the Galaxy. We show that,
if this scenario is correct, and if the original binary properties are similar
to those in the local stellar neighbourhood, then the hypervelocity stars
should rotate with velocities measureably lower than those for field stars of
similar spectral type. This may prove to be a more direct test of the model
than trying to predict the position and velocity distributions.


title: Foundations of multiple black hole evolutions

abstract:
  We present techniques for long-term, stable, and accurate evolutions of
multiple-black-hole spacetimes using the `moving puncture' approach with
fourth- and eighth-order finite difference stencils. We use these techniques to
explore configurations of three black holes in a hierarchical system consisting
of a third black hole approaching a quasi-circular black-hole binary, and find
that, depending on the size of the binary, the resulting encounter may lead to
a prompt merger of all three black holes, production of a highly elliptical
binary (with the third black hole remaining unbound), or disruption of the
binary (leading to three free black holes). We also analyze the classical
Burrau three-body problem using full numerical evolutions. In both cases, we
find behaviors distinctly different from Newtonian predictions, which has
important implications for N-body black-hole simulations. For our simulations
we use analytic approximate data. We find that the eighth-order stencils
significantly reduce the numerical errors for our choice of grid sizes, and
that the approximate initial data produces the expected waveforms (after a
rescaling of the puncture masses) for black-hole binaries with modest initial
separations.


title: Lagrangean stability of slow dynamos in compact 3D Riemannian manifolds

abstract:
  Modifications on a recently introduced fast dynamo operator by Chiconne et al
[Comm Math Phys 173, 379 (1995)] in compact 3D Riemannian manifolds allows us
to shown that slow dynamos are Lagrangean stable, in the sense that the
sectional curvature of the Riemann manifold vanishes. The stability of the
holonomic filament in this manifold will depend upon the sign of the second
derivative of the pressure along the filament and in the non-holonomic case, to
the normal pressure of the filament. Lagrangean instability is also
investigated in this case and again an dynamo operator can be defined in this
case. Negative curvature (Anosov flows) dynamos are also discussed in their
stability aspects.


title: The Dust Content of Galaxy Clusters

abstract:
  We report on the detection of reddening toward z ~ 0.2 galaxy clusters. This
is measured by correlating the Sloan Digital Sky Survey cluster and quasar
catalogs and by comparing the photometric and spectroscopic properties of
quasars behind the clusters to those in the field. We find mean E(B-V) values
of a few times 10^-3 mag for sight lines passing ~Mpc from the clusters'
center. The reddening curve is typical of dust but cannot be used to
distinguish between different dust types. The radial dependence of the
extinction is shallow near the cluster center suggesting that most of the
detected dust lies at the outskirts of the clusters. Gravitational
magnification of background z ~ 1.7 sources seen on Mpc (projected) scales
around the clusters is found to be of order a few per cent, in qualitative
agreement with theoretical predictions. Contamination by different spectral
properties of the lensed quasar population is unlikely but cannot be excluded.


title: Tuning impurity states in bilayer graphene

abstract:
  We study the impurity states in bilayer graphene in the unitary limit using
Green's function method. Unlike in single layer graphene, the presence of
impurities at two non-equivalent sites in bilayer graphene produce different
impurity states which is understood as the change in the band structure due to
interlayer hopping of electrons. The impurity states can also be tuned by
changing the band structure of bilayer grahene through external electric field
bias.


title:
Monte Carlo simulations of pulse propagation in massive multichannel
  optical fiber communication systems

abstract:
  We study the combined effect of delayed Raman response and bit pattern
randomness on pulse propagation in massive multichannel optical fiber
communication systems. The propagation is described by a perturbed stochastic
nonlinear Schr\"odinger equation, which takes into account changes in pulse
amplitude and frequency as well as emission of continuous radiation. We perform
extensive numerical simulations with the model, and analyze the dynamics of the
frequency moments, the bit-error-rate, and the mutual distribution of amplitude
and position. The results of our numerical simulations are in good agreement
with theoretical predictions based on the adiabatic perturbation approach.


title: The origin and evolution of dust in high-redshift galaxies

abstract:
  Dusty hyperluminous galaxies in the early universe provide unique
environments for studying the role of massive stars in the formation and
destruction of dust. At redshifts above 6, when the universe was less than 1
Gyr old, dust could have only condensed in the explosive ejecta of Type II
supernovae (SNe), since most of the progenitors of the AGB stars, the major
alternative source of interstellar dust, did not have time to evolve off the
main sequence. We present analytical models for the evolution of the gas, dust,
and metals in high redshift galaxies, with a special application to SDSS
J1148+5251, a hyperluminous quasar at z = 6.4. We show that an average SN must
condense at least 1 Msun of dust to account for the mass of dust in this
object, when grain destruction by supernova remnants (SNRs) is taken into
account. This required yield is in excess of ~0.05 Msun, the largest mass of
dust inferred from infrared observations of Cas A. If the yield of Cas A is
typical, then other processes, such as accretion onto preexisting grains in
molecular clouds is needed to produce the mass of dust in J1148+5251. For such
process to be effective, SNR must significantly increase, presumably by
non-evaporative grain-grain collisions during the late stages of their
evolution, the number of nucleation centers onto which refractory elements can
condense in molecular clouds.


title:
Spatially Resolved Galaxy Star Formation and its Environmental
  Dependence I

abstract:
  We use the photometric information contained in individual pixels of 44,964
(0.019<z<0.125 and -23.5<M_r<-20.5) galaxies in the Fourth Data Release (DR4)
of the Sloan Digital Sky Survey to investigate the effects of environment on
galaxy star formation (SF). We use the pixel-z technique, which combines
stellar population synthesis models with photometric redshift template fitting
on the scale of individual pixels in galaxy images. Spectral energy
distributions are constructed, sampling a wide range of properties such as age,
star formation rate (SFR), dust obscuration and metallicity. By summing the
SFRs in the pixels, we demonstrate that the distribution of total galaxy SFR
shifts to lower values as the local density of surrounding galaxies increases,
as found in other studies. The effect is most prominent in the galaxies with
the highest star formation, and we see the break in the SFR-density relation at
a local galaxy density of $\approx 0.05 $(Mpc/h)$^{-3}$. Since our method
allows us to spatially resolve the SF distribution within galaxies, we can
calculate the mean SFR of each galaxy as a function of radius. We find that on
average the mean SFR is dominated by SF in the central regions of galaxies, and
that the trend for suppression of SFR in high density environments is driven by
a reduction in this nuclear SF. We also find that the mean SFR in the outskirts
is largely independent of environmental effects. This trend in the mean SFR is
shared by galaxies which are highly star forming, while those which are weakly
star forming show no statistically significant correlation between their
environment and the mean SFR at any radius.


title: Transmission phase of a singly occupied quantum dot in the Kondo regime

abstract:
  We report on the phase measurements on a quantum dot containing a single
electron in the Kondo regime. Transport takes place through a single orbital
state. Although the conductance is far from the unitary limit, we measure for
the first time, a transmission phase as theoretically predicted of \pi/2. As
the dot's coupling to the leads is decreased, with the dot entering the Coulomb
blockade regime, the phase reaches a value of \pi. Temperature shows little
effect on the phase behaviour in the range 30--600 mK, even though both the
two-terminal conductance and amplitude of the Aharonov-Bohm oscillations are
strongly affected. These results confirm that previous phase measurements
involved transport through more than a single level.


title:
Equilibrium and nonequilibrium properties of systems with long-range
  interactions

abstract:
  We briefly review some equilibrium and nonequilibrium properties of systems
with long-range interactions. Such systems, which are characterized by a
potential that weakly decays at large distances, have striking properties at
equilibrium, like negative specific heat in the microcanonical ensemble,
temperature jumps at first order phase transitions, broken ergodicity. Here, we
mainly restrict our analysis to mean-field models, where particles globally
interact with the same strength. We show that relaxation to equilibrium
proceeds through quasi-stationary states whose duration increases with system
size. We propose a theoretical explanation, based on Lynden-Bell's entropy, of
this intriguing relaxation process. This allows to address problems related to
nonequilibrium using an extension of standard equilibrium statistical
mechanics. We discuss in some detail the example of the dynamics of the free
electron laser, where the existence and features of quasi-stationary states is
likely to be tested experimentally in the future. We conclude with some
perspectives to study open problems and to find applications of these ideas to
dipolar media.


title:
The space-time operator product expansion in string theory duals of
  field theories

abstract:
  We study the operator product expansion (OPE) limit of correlation functions
in field theories which possess string theory duals, from the point of view of
the string worldsheet. We show how the interesting ("single-trace") terms in
the OPE of the field theory arise in this limit from the OPE of the worldsheet
theory of the string dual, using a dominant saddle point which appears in
computations of worldsheet correlation functions in the space-time OPE limit.
The worldsheet OPE generically contains only non-physical operators, but all
the non-physical contributions are resummed by the saddle point to a
contribution similar to that of a physical operator, which exactly matches the
field theory expectations. We verify that the OPE limit of the worldsheet
theory does not have any other contributions to the OPE limit of space-time
correlation functions. Our discussion is completely general and applies to any
local field theory (conformal at high energies) that has a weakly coupled
string theory dual (with arbitrary curvature). As a first application, we
compare our results to a proposal of R. Gopakumar for the string theory dual of
free gauge theories.


title:
Energy and System-Size Dependence of Long-Range Multiplicity
  Correlations from the STAR Experiment

abstract:
  A discussion of results for short and long-range multiplicity correlations
(forward-backward) are presented for several systems (Au+Au, Cu+Cu, and pp) and
energies (e.g. $\sqrt{s_{NN}}$ = 200, 62.4, and $\approx$ 20 GeV). These
correlations are measured with increasing values of a gap in pseudorapidity,
from no gap at midrapidity to a separation of 1.6 units ($|\eta|$ = 0.8). For
the highest energy, central A+A collisions, the forward-backward correlation
strength maintains a constant value across the measurement region. In
peripheral collisions, at lower energies, and in pp data, the maximum appears
at midrapidity. This result may indicate the possible formation of high density
matter for central A+A collisions at $\sqrt{s_{NN}}$ = 200 GeV.


title:
Towards 4-loop NSPT result for a 3-dimensional condensate-contribution
  to hot QCD pressure

abstract:
  Thanks to dimensional reduction, the contributions to the hot QCD pressure
coming from so-called soft modes can be studied via an effective
three-dimensional theory named Electrostatic QCD (spatial Yang-Mills fields
plus an adjoint Higgs scalar). The poor convergence of the perturbative series
within EQCD suggests to perform lattice measurements of some of the associated
gluon condensates. These turn out, however, to be plagued by large
discretization artifacts. We discuss how Numerical Stochastic Perturbation
Theory can be exploited to determine the full lattice spacing dependence of one
of these condensates up to 4-loop order, and sharpen our tools on a concrete
2-loop example.


title: Considerations on P vs NP

abstract:
  In order to prove that the P of problems is different to the NP class, we
consider the satisfability problem of propositional calculus formulae, which is
an NP-complete problem. It is shown that, for every search algorithm A, there
is a set E(A) containing propositional calculus formulae, each of which
requires the algorithm A to take non-polynomial time to find the truth-values
of its propositional letters satisfying it. Moreover, E(A)'s size is an
exponential function of n, which makes it impossible to detect such formulae in
a polynomial time. Hence, the satisfability problem does not have a polynomial
complexity


title: Functional Determinants in Quantum Field Theory

abstract:
  Functional determinants of differential operators play a prominent role in
theoretical and mathematical physics, and in particular in quantum field
theory. They are, however, difficult to compute in non-trivial cases. For one
dimensional problems, a classical result of Gel'fand and Yaglom dramatically
simplifies the problem so that the functional determinant can be computed
without computing the spectrum of eigenvalues. Here I report recent progress in
extending this approach to higher dimensions (i.e., functional determinants of
partial differential operators), with applications in quantum field theory.


title: Holographic glueball structure

abstract:
  We derive and systematically analyze scalar glueball correlation functions in
both the hard-wall and dilaton soft-wall approximations to holographic QCD. The
dynamical content of the holographic correlators is uncovered by examining
their spectral density and by relating them to the operator product expansion,
a dilatational low-energy theorem and a recently suggested two-dimensional
power correction associated with the short-distance behavior of the heavy-quark
potential. This approach provides holographic estimates for the three
lowest-dimensional gluon condensates or alternatively their Wilson
coefficients, the two leading moments of the instanton size distribution in the
QCD vacuum and an effective UV gluon mass. A remarkable complementarity between
the nonperturbative physics of the hard- and soft-wall correlators emerges, and
their ability to describe detailed QCD results can be assessed quantitatively.
We further provide the first holographic estimates for the decay constants of
the 0++ glueball and its excitations. The hard-wall background turns out to
encode more of the relevant QCD physics, and its prediction f ~ 0.8-0.9 GeV for
the phenomenologically important ground state decay constant agrees inside
errors with recent QCD sum rule and lattice results.


title: Convergence of Diagonal Ergodic Averages

abstract:
  Tao has recently proved that if $T_1,...,T_l$ are commuting, invertible,
measure-preserving transformations on a dynamical system then for any
$L^\infty$ functions $f_1,...,f_l$, the average
$\frac{1}{N}\sum_{n=0}^{N-1}\prod_{i\leq l}f_i\circ T^n_i$ converges in the
$L^2$ norm. Tao's proof is unusual in that it translates the problem into a
more complicated statement about the combinatorics of finite spaces by using
the Furstenberg correspondence "backwards". In this paper, we give an ergodic
proof of this theorem, essentially a translation of Tao's argument to the
ergodic setting. In order to do this, we develop two new variations on the
usual Furstenberg correspondence, both of which take recurrence-type statements
in one dynamical system and give equivalent statements in a different dynamical
system with desirable properties.


title: Gorenstein categories and Tate cohomology on projective schemes

abstract:
  We study Gorenstein categories. We show that such a category has Tate
cohomological functors and Avramov-Martsinkovsky exact sequences connecting the
Gorenstein relative, the absolute and the Tate cohomological functors. We show
that such a category has what Hovey calls an injective model structure and also
a projective model structure in case the category has enough projectives. As
examples we show that if X is a locally Gorenstein projective scheme then the
category Qco(X) of quasi-coherent sheaves on $X$ is such a category and so has
these features.


title: Conformal Graph Directed Markov Systems

abstract:
  We present the main concepts and results for Graph Directed Markov Systems
that have a finitely irreducible incidence matrix. We then see how these
results change when the incidence matrix is not assumed to be finitely
irreducible.


title:
A Precise Measurement of the Muon Neutrino-Nucleon Inclusive Charged
  Current Cross-Section off an Isoscalar Target in the Energy Range 2.5 < E_\nu
  < 40 GeV by NOMAD

abstract:
  We present a measurement of the muon neutrino-nucleon inclusive charged
current cross-section, off an isoscalar target, in the neutrino energy range
$2.5 \leq E_\nu \leq 40$ GeV. The significance of this measurement is its
precision, $\pm 4$% in $2.5 \leq E_\nu \leq 10$ GeV, and $\pm 2.6$% in $10 \leq
E_\nu \leq 40$ GeV regions, where significant uncertainties in previous
experiments still exist, and its importance to the current and proposed long
baseline neutrino oscillation experiments.


title: Muonic atoms with extreme nuclear charge

abstract:
  Bound muons (also pions, kaons, etc) increase the fission barrier and produce
some stabilizing effects for highly charged nuclei. If the binding energy of
the muon exceeds $mc^2$, it becomes stable. The $1s$ state of a muon inside an
exotic nucleus with atomic number $A= 5Z/2$ and such large charge $Z$ that the
$1s$ energy $E$ is in the range $0\le E<-mc^2$ is considered.


title: Complete r-partite subgraphs of dense r-graphs

abstract:
  We determine how large r-partite graphs can be found in r-uniform graphs with
n vertices and Cn^r edges, where C is a slowly decreasing function of n. This
refines results of Erdos from 1964.


title: Degree Complexity of a Family of Birational Maps

abstract:
  We compute the degree complexity of a family of birational mappings of the
plane with high order singularities.


title: Anti-solar differential rotation and surface flow pattern on UZ Librae

abstract:
  We re-investigate UZ Librae spectra obtained at KPNO in 1998 and 2000. From
the 1998 data we compose 11 consecutive Doppler images using the Ca I-6439, Fe
I-6393 and Fe I-6411 lines. Applying the method of average cross-correlation of
contiguous Doppler images we find anti-solar differential rotation with a
surface shear of alpha ~ -0.03. The pilot application of the local correlation
tracking technique for the same data qualitatively confirms this result and
indicates complex flow pattern on the stellar surface. From the
cross-correlation of the two available Doppler images in 2000 we also get
anti-solar differential rotation but with a much weaker shear of alpha ~
-0.004.


title: Spatial random permutations and infinite cycles

abstract:
  We consider systems of spatial random permutations, where permutations are
weighed according to the point locations. Infinite cycles are present at high
densities. The critical density is given by an exact expression. We discuss the
relation between the model of spatial permutations and the ideal and
interacting quantum Bose gas.


title: Clique Minors in Cartesian Products of Graphs

abstract:
  A "clique minor" in a graph G can be thought of as a set of connected
subgraphs in G that are pairwise disjoint and pairwise adjacent. The "Hadwiger
number" h(G) is the maximum cardinality of a clique minor in G. This paper
studies clique minors in the Cartesian product G*H.
  Our main result is a rough structural characterisation theorem for Cartesian
products with bounded Hadwiger number. It implies that if the product of two
sufficiently large graphs has bounded Hadwiger number then it is one of the
following graphs:
  - a planar grid with a vortex of bounded width in the outerface,
  - a cylindrical grid with a vortex of bounded width in each of the two `big'
faces, or
  - a toroidal grid.
  Motivation for studying the Hadwiger number of a graph includes Hadwiger's
Conjecture, which states that the chromatic number chi(G) <= h(G). It is open
whether Hadwiger's Conjecture holds for every Cartesian product. We prove that
if |V(H)|-1 >= chi(G) >= chi(H) then Hadwiger's Conjecture holds for G*H. On
the other hand, we prove that Hadwiger's Conjecture holds for all Cartesian
products if and only if it holds for all G * K_2. We then show that h(G * K_2)
is tied to the treewidth of G.
  We also develop connections with pseudoachromatic colourings and connected
dominating sets that imply near-tight bounds on the Hadwiger number of grid
graphs (Cartesian products of paths) and Hamming graphs (Cartesian products of
cliques).


title:
Pushnitski's $\mu$-invariant and Schr\"odinger operators with embedded
  eigenvalues

abstract:
  In this note, under a certain assumption on an affine space of operators,
which admit embedded eigenvalues, it is shown that the singular part of the
spectral shift function of any pair of operators from this space is an
integer-valued function. The proof uses a natural decomposition of Pushnitski's
$\mu$-invariant into "absolutely continuous" and "singular" parts. As a
corollary, the Birman-Krein formula follows.


title:
High Strain and Strain-Rate Behaviour of PTFE/Aluminium/Tungsten
  Mixtures

abstract:
  Conventional drop-weight techniques were modified to accommodate
low-amplitude force transducer signals from low-strength, cold isostatically
pressed 'heavy' composites of polytetrafluoroethylene, aluminum and tungsten.
The failure strength, strain and the post-critical behavior of failed samples
were measured for samples of different porosity and tungsten grain size.
Unusual phenomenon of significantly higher strength (55 MPa) of porous
composites (density 5.9 g/cc) with small W particles (less than 1 micron) in
comparison with strength (32 MPa) of dense composites (7.1 g/cc) with larger W
particles (44 microns) at the same volume content of components was observed.
This is attributed to force chains created by a network of small W particles.
Interrupted tests at different levels of strain revealed the mechanisms of
fracture under dynamic compression.


title:
Superfluid Density in High-$T_c$ Superconductors: Enabled by Holes or
  Suppressed by Electrons?

abstract:
  The critical temperature of an underdoped cuprate superconductor is limited
by its phase stiffness $\rho$. In this Letter we argue that the dependence of
$\rho$ on doping $x$ should be understood as a consequence of deleterious
competition with antiferromagnetism at large electron densities, rather than as
evidence for pairing of holes in the $x =0$ Mott insulator state. Our proposal
is based on the observation that the correlation energy of a d-wave
superconductor increases in magnitude at finite pairing wavevector when
antiferromagnetic fluctuations are strong.


title:
Imposition of Different Optimizing Object with Non-Linear Constraints on
  Flux Sampling and Elimination of Free Futile Pathways

abstract:
  Constraint-based modeling has been widely used on metabolic networks
analysis, such as biosynthetic prediction and flux optimization. The linear
constraints, like mass conservation constraint, reversibility constraint,
biological capacity constraint, can be imposed on linear algorithms. However,
recently a non-linear constraint based on the second thermodynamic law, known
as "loop law", has emerged and challenged the existing algorithms. Proven to be
unfeasible with linear solutions, this non-linear constraint has been
successfully imposed on the sampling process. In this place, Monte - Carlo
sampling with Metropolis criterion and Simulated Annealing has been introduced
to optimize the Biomass synthesis of genome scale metabolic network of
Helicobacter pylori (iIT341 GSM / GPR) under mass conservation constraint,
biological capacity constraint, and thermodynamic constraints including
reversibility and "loop law". The sampling method has also been employed to
optimize a non-linear objective function, the Biomass synthetic rate, which is
unified by the total income number of reducible electrons. To verify whether a
sample contains internal loops, an automatic solution has been developed based
on solving a set of inequalities. In addition, a new type of pathway has been
proposed here, the Futile Pathway, which has three properties: 1) its mass flow
could be self-balanced; 2) it has exchange reactions; 3) it is independent to
the biomass synthesis. To eliminate the fluxes of the Futile Pathways in the
sampling results, a linear programming based method has been suggested and the
results have showed improved correlations among the reaction fluxes in the
pathways related to Biomass synthesis.


title:
On $pp \to p K \Lambda, N K \Sigma, pp \phi$ -- the basic ingredients
  for strangeness production in heavy ion collisions

abstract:
  The strangeness production in heavy ion collisions was proposed to be probes
of the nuclear equation of state, Kaon potential in nuclear medium, strange
quark matter and quark-gluon plasma, etc. However, to act as reliable probes,
proper understanding of the basic ingredients for the strangeness production,
such as $pp \to pK^+\Lambda$, $pp \to pp \phi$ and $pp \to nK^+\Sigma^+$ is
necessary. Recent study of these reactions clearly shows that previously
ignored contributions from the spin-parity $1/2^-$ resonances, $N^*(1535)$ and
$\Delta^*(1620)$, are in fact very important for these reactions, especially
for near-threshold energies. It is necessary to include these contributions for
getting reliable calculation for the strangeness production in heavy ion
collisions.


title:
Models of Type I X-ray Bursts from GS 1826-24: A Probe of rp-Process
  Hydrogen Burning

abstract:
  The X-ray burster GS 1826-24 shows extremely regular Type I X-ray bursts
whose energetics and recurrence times agree well with thermonuclear ignition
models. We present calculations of sequences of burst lightcurves using
multizone models which follow the rp-process nucleosynthesis with an extensive
nuclear reaction network. The theoretical and observed burst lightcurves show
remarkable agreement. The models naturally explain the slow ~5s rise and long
~100s tails of these bursts, as well as their dependence on mass accretion
rate. This comparison provides further evidence for solar metallicity in the
accreted material in this source, and constrains the distance to the source.
The main difference is that the observed lightcurves do not show the distinct
two-stage rise of the models. This may reflect the time for burning to spread
over the stellar surface, or may indicate that our treatment of heat transport
or nuclear physics needs to be revised. The trends in burst properties with
accretion rate are well-reproduced by our spherically symmetric models which
include chemical and thermal inertia from the ashes of previous bursts. Changes
in the covering fraction of the accreted fuel are not required.


title: Observations of Six Glitches in PSR B1737-30

abstract:
  Six glitches have been recently observed in the rotational frequency of the
young pulsar PSR B1737-30 (J1740-3015) using the 25-m Nanshan telescope of
Urumqi Observatory. With a total of 20 glitches in 20 years, it is one of the
most frequently glitching pulsars of the about 1750 known pulsars. Glitch
amplitudes are very variable with fractional increases in rotation rate ranging
from 10^{-9} to 10^{-6}. Inter-glitch intervals are also very variable, but no
relationship is observed between interval and the size of the preceding glitch.
There is a persistent increase in |\dot\nu|, opposite in sign to that expected
from slowdown with a positive braking index, which may result from changes in
the effective magnetic dipole moment of the star during the glitch.


title: "Gravitational mass" of information?

abstract:
  We hypothesize possible new types of forces that would be the result of new
types of interactions, static and a slow transient, between objects with
related information contents (pattern). Such mechanism could make material
composition dependence claimed by Fishbach, et al in Eotvos type experiments
plausible. We carried out experiments by using a high-resolution scale with the
following memories: USB-2 flash drives (1-16GB), DVD and CD disks to determine
if such an interaction exist/detectable with a scale resolution of 10 microgram
with these test objects. We applied zero information, white noise and 1/f noise
type data. Writing or deleting the information in any of these devices causes
peculiar negative weight transients, up to milligrams (mass fraction around
10^-5), which is followed by various types of relaxation processes. These
relaxations have significantly different dynamics compared to transients
observed during cooling after stationary external heating. Interestingly, a
USB-1 MP3 player has also developed comparable transient mass loss during
playing music. A classical interpretation of the negative weight transients
could be absorbed water in hygroscopic components however comparison of
relaxation time constants with air humidity data does not support an obvious
explanation. Another classical interpretation with certain contribution is the
lifting Bernoulli force caused by the circulation due to convection of the warm
air. However, in this case all observed time constants with a device should
have been the same unless some hidden parameter causes the observed variations.
Further studies are warranted to clarify if there is indeed a new force, which
is showing up as negative mass at weight measurement when high-density
structural information is changed or read out (measured).


title:
Prospects of cold dark matter searches with an ultra-low-energy
  germanium detector

abstract:
  The report describes the research program on the development of
ultra-low-energy germanium detectors, with emphasis on WIMP dark matter
searches. A threshold of 100 eV is achieved with a 20 g detector array,
providing a unique probe to the low-mas WIMP. Present data at a surface
laboratory is expected to give rise to comparable sensitivities with the
existing limits at the $\rm{5 - 10 GeV}$ WIMP-mass range. The projected
parameter space to be probed with a full-scale, kilogram mass-range experiment
is presented. Such a detector would also allow the studies of neutrino-nucleus
coherent scattering and neutrino magnetic moments.


title: Continuous Opinions and Discrete Actions in Opinion Dynamics Problems

abstract:
  A model where agents show discrete behavior regarding their actions, but have
continuous opinions that are updated by interacting with other agents is
presented. This new updating rule is applied to both the voter and Sznajd
models for interaction between neighbors and its consequences are discussed.
The appearance of extremists is naturally observed and it seems to be a
characteristic of this model.


title:
The classification of $\bf Z$-graded modules of the intermediate series
  over the $q$-analog Virasoro-like algebra

abstract:
  In this paper, we complete the classification of the {\bf Z}-graded modules
of the intermediate series over the $q$-analog Virasoro-like algebra $L$. We
first construct four classes of irreducible {\bf Z}-graded $L$-modules of the
intermediate series. Then we prove that any {\bf Z}-graded $L$-modules of the
intermediate series must be the direct sum of some trivial $L$-modules or one
of the modules constructed by us.


title: Suzaku Detection of an Intense X-Ray Flare from an A-type Star HD161084

abstract:
  We report a serendipitous detection of an intense X-ray flare from the Tycho
reference source HD 161084 during a Suzaku observation of the Galactic Center
region for 20 ks. The X-ray Imaging Spectrometer (XIS) recorded a flare from
this A1-type dwarf or subgiant star with a flux of 1.4x10^{-12} erg s^{-1}
cm^{-2} (0.5--10 keV) and a decay time scale of 0.5 hr. The spectrum is hard
with a prominent Fe XXV K alpha emission line at 6.7 keV, which is explained by
a 5 keV thin-thermal plasma model attenuated by a 1.4x10^{21} cm^{-2}
extinction. The low extinction, which is consistent with the optical reddening,
indicates that the source is a foreground star toward the Galactic Center
region. Based on the spectroscopic parallax distance of 530 pc, the peak X-ray
luminosity amounts to 1x10^{32} erg s^{-1} (0.5--10 keV). This is much larger
than the X-ray luminosity of ordinary late-type main-sequence stars, and the
X-ray emission is unattributable to a hidden late-type companion that comprises
a wide binary system with the A-star. We discuss possible natures of HD 161084
and suggest that it is most likely an interacting binary with elevated magnetic
activity in the companion such as the Algol-type system. The flux detected by
Suzaku during the burst is 100 times larger than the quiescent level measured
using the archived XMM-Newton and Chandra data. The large flux amplification
makes this star a unique example among sources of this class.


title: Resonant Transmission of a Light Pulse through a Quantum Well

abstract:
  Reflectance, transmittance and absorbance of a symmetric light pulse, the
carrying frequency of which is close to the frequency of interband transitions
in a quantum well, are calculated. Energy levels of the quantum well are
assumed discrete, and two closely located excited levels are taken into
account. The theory is applicable for the quantum wells of arbitrary widths
when the size quantization is preserved. A distinction of refraction indices of
barriers and quantum well is taken into account. In such a case, some
additional reflection from the quantum well borders appears which changes
essentially a shape of the reflected pulse in comparison to homogeneous medium.
The reflection from the borders disappears at some definite ratios of the
carrying frequency of the stimulating pulse and quantum well width.


title: Introduction to the theory of quasi-log varieties

abstract:
  This paper is a gentle introduction to the theory of quasi-log varieties by
Ambro. We explain the fundamental theorems for the log minimal model program
for log canonical pairs. More precisely, we give a proof of the base point free
theorem for log canonical pairs in the framework of the theory of quasi-log
varieties.


title: Relationship between Magnetic Structure and Ferroelectricity of LiVCuO4

abstract:
  Neutron scattering studies and measurements of the dielectric susceptibility
and ferroelectric polarization P have been carried out in various magnetic
fields H for single-crystal samples of the multiferroic system LiVCuO4 with
quasi one-dimensional spin 1/2 Cu2+ chains formed of edge-sharing CuO4 square
planes, and the relationship between the magnetic structure and
ferroelectricity has been studied. The ferroelectric polarization is
significantly suppressed by the magnetic field H above 2 T applied along a and
b axes. The helical magnetic structure with the helical axis parallel to c has
been confirmed in H=0, and for H//a, the spin flop transition takes place at
H=2 T with increasing H, where the helical axis changes to the direction
parallel to H. The ferroelectric polarization along a at H=0 is found to be
proportional to the neutron magnetic scattering intensity, indicating that the
magnetic order is closely related to the appearance of the ferroelectricity.
The relationship between the magnetic structure and ferroelectricity of LiVCuO4
is discussed by considering the existing theories.


title:
Rational Integrals of the second kind on a complex projective manifold
  and its primitive cohomology

abstract:
  Let X be a complex algebraic manifold of dimension n+1 embedded in a
sufficiently higher dimensional complex projective space, and Y a generic
hyperplane section of X. We describe the mixed Hodge structure on H^p(X-Y,C)
and the Hodge filtration of the middle primitive cohomology group H^n(Y,C)_0 of
Y in terms of rational integrals on X. (Key words: Primitive cohomology,
Rational integral of the 2nd kind, Generalized Poincare residue map, Hodge
filtration, Mixed Hodge structure)


title: How does Casimir energy fall? III. Inertial forces on vacuum energy

abstract:
  We have recently demonstrated that Casimir energy due to parallel plates,
including its divergent parts, falls like conventional mass in a weak
gravitational field. The divergent parts were suitably interpreted as
renormalizing the bare masses of the plates. Here we corroborate our result
regarding the inertial nature of Casimir energy by calculating the centripetal
force on a Casimir apparatus rotating with constant angular speed. We show that
the centripetal force is independent of the orientation of the Casimir
apparatus in a frame whose origin is at the center of inertia of the apparatus.


title:
A note on proper conformal vector fields in cylindrically symmetric
  static space-times

abstract:
  A study of proper conformal vector field in non conformally flat
cylindrically symmetric static space-times is given by using direct integration
technique. Using the above mentioned technique we have shown that a very
special class of the above space-time admits proper conformal vector field.


title: Finite dimensional subspaces of noncommutative $L_p$ spaces

abstract:
  We prove the following noncommutative version of Lewis's classical result.
Every n-dimensional subspace E of Lp(M) (1<p<\infty) for a von Neumann algebra
M satisfies d_{cb}(E, RC^n_{p'}) \leq c_p n^{\abs{1/2-1/p}} for some constant
c_p depending only on $p$, where $1/p +1/p' =1$ and $RC^n_{p'} = [R_n\cap C_n,
R_n+C_n]_{1/p'}$. Moreover, there is a projection $P:Lp(M) --> Lp(M)$ onto E
with $\norm{P}_{cb} \leq c_p n^{\abs{1/2-1/p}}.$ We follow the classical change
of density argument with appropriate noncommutative variations in addition to
the opposite trick.


title: Thermodynamics on the apparent horizon in generalized gravity theories

abstract:
  We present a general procedure to construct the first law of thermodynamics
on the apparent horizon and illustrate its validity by examining it in some
extended gravity theories. Applying this procedure, we can describe the
thermodynamics on the apparent horizon in Randall-Sundrum braneworld imbedded
in a nontrivial bulk. We discuss the mass-like function which was used to link
Friedmann equation to the first law of thermodynamics and obtain its special
case which gives the generalized Misner-Sharp mass in Lovelock gravity.


title: Local Equivalence of Rank-Two Quantum Mixed States

abstract:
  We investigate the equivalence of quantum mixed states under local unitary
transformations. For a class of rank-two mixed states, a sufficient and
necessary condition of local equivalence is obtained by giving a complete set
of invariants under local unitary transformations, such that two states in this
class are locally equivalent if and only if all these invariants have equal
values for them.


title: Differential Geometry of Bipartite Quantum States

abstract:
  We investigate the differential geometry of bipartite quantum states. In
particular the manifold structures of pure bipartite states are studied in
detail. The manifolds with respect to all normalized pure states of arbitrarily
given Schmidt ranks or Schmidt coefficients are explicitly presented. The
dimensions of the related manifolds are calculated.


title:
Johnson-Cousins magnitudes of comparison stars in the fields of ten
  Seyfert galaxies

abstract:
  We present UBVRcIc magnitudes of 49 comparison stars in the fields of the
Seyfert galaxies Mrk 335, Mrk 79, Mrk 279, Mrk 506, 3C 382, 3C 390.3, NGC 6814,
Mrk 304, Ark 564, and NGC 7469 in order to facilitate the photometric
monitoring of these objects; 36 of the stars have not been calibrated before.
The comparison stars are situated in 5x5 arcmin fields centred on the Seyfert
galaxies, their V band flux ranges from 11.7 to 18.2 mag with a median value of
16.3 mag, and their B-V colour index ranges from 0.4 to 1.6 mag with a median
value of 0.8 mag. The median errors of the calibrated UBVRcIc magnitudes are
0.08, 0.04, 0.03, 0.04, and 0.06 mag, respectively. Comparison stars were
calibrated for the first time in three of the fields (Mrk 506, 3C 382, and Mrk
304). The comparison sequences in the other fields were improved in various
aspects. Extra stars were calibrated in four fields (Mrk 335, Mrk 79, NGC 6814,
and NGC 7469) - most of these stars are fainter and are situated closer to the
Seyfert galaxies compared to the existing comparison stars. The passband
coverage of the sequences in five fields (Mrk 335, Mrk 79, Mrk 279, NGC 6814,
and Ark 564) was complemented with U band.


title:
Invariant Linearization Criteria for Systems of Cubically Semi-Linear
  Second-Order Ordinary Differential Equations

abstract:
  Invariant linearization criteria of square systems of second-order
quadratically semi-linear ordinary differential equations (ODEs) that can be
represented as geodesic equations are extended to square systems of ODEs
cubically nonlinear in the first derivatives. It is shown that there are two
branches for the linearization problem via point transformations for an
arbitrary system of second-order ODEs. One is when the system is at most cubic
in the first derivatives. We solve this branch of the linearization problem by
point transformations in the case of a square sytem of two second-order ODEs.
Necessary and sufficient conditions for linearization by means of point
transformations are given in terms of coefficient functions of the system of
two second-order ODEs cubically nonlinear in the first derivatives. A
consequence of our geometric approach of projection is a re-derivation of Lie's
conditions for a single second-order ODE and sheds light on more recent results
on them. In particular, we show here how one can construct point
transformations for reduction to the simplest linear equation by going to the
higher space and just utilising the coefficients of the original ODE. We also
obtain invariant criteria for the reduction of a linear square system to the
simplest system. Moreover, these results contain the quadratic case as a
special case. Examples are given to illustrate our results.


title: Linearizability Criteria for a Class of Third Order Semi-Linear ODEs

abstract:
  Using geometric methods for linearizing systems of second order cubically
semi-linear ordinary differential equations, we extend to the third order by
differentiating the second order equation. This yields criteria for
linearizability of a class of third order semi-linear ordinary differential
equations, which is distinct from the classes available in the literature. Some
examples are given and discussed.


title:
Conditional linearizability criteria for a system of third-order
  ordinary differential equations

abstract:
  We provide linearizability criteria for a class of systems of third-order
ordinary differential equations (ODEs) that is cubically semi-linear in the
first derivative, by differentiating a system of second-order quadratically
semi-linear ODEs and using the original system to replace the second
derivative. The procedure developed splits into two cases, those where the
coefficients are constant and those where they are variables. Both cases are
discussed and examples given.


title: Pseudospin Soliton in the $\nu=1$ Bilayer Quantum Hall State

abstract:
  We investigate a domain structure of pseudospins, a soliton lattice in the
bilayer quantum Hall state at total Landau level filling factor $\nu =1$, in a
tilted magnetic field, where the pseudospin represents the layer degree of
freedom. An anomalous peak in the magnetoresistance $R_{xx}$ appears at the
transition point between the commensurate and incommensurate phases. The
$R_{xx}$ at the peak is highly anisotropic for the angle between the in-plain
magnetic field $B_\parallel $ and the current, and indicates a formation of the
soliton lattice aligned parallel to $B_\parallel $. Temperature dependence of
the $R_{xx}$ peak reveals that the dissipation is caused by thermal
fluctuations of pseudospin solitons. We construct a phase diagram of the
bilayer $\nu =1$ system as a function of $B_\parallel$ and the total electron
density. We also study effects of density imbalance between the two layers.


title: Constructing a Space from the System of Geodesic Equations

abstract:
  Given a space it is easy to obtain the system of geodesic equations on it. In
this paper the inverse problem of reconstructing the space from the geodesic
equations is addressed. A procedure is developed for obtaining the metric
tensor from the Christoffel symbols. The procedure is extended for determining
if a second order quadratically semi-linear system can be expressed as a system
of geodesic equations, provided it has terms only quadratic in the first
derivative apart from the second derivative term. A computer code has been
developed for dealing with larger systems of geodesic equations.


title:
The two-body random spin ensemble and a new type of quantum phase
  transition

abstract:
  We study the properties of a two-body random matrix ensemble for
distinguishable spins. We require the ensemble to be invariant under the group
of local transformations and analyze a parametrization in terms of the group
parameters and the remaining parameters associated with the "entangling" part
of the interaction. We then specialize to a spin chain with nearest neighbour
interactions and numerically find a new type of quantum phase transition
related to the strength of a random external field i.e. the time reversal
breaking one body interaction term.


title:
Adaptive Speckle Imaging Interferometry: a new technique for the
  analysis of microstructure dynamics, drying processes and coating formation

abstract:
  We describe an extension of multi-speckle diffusing wave spectroscopy adapted
to follow the non-stationary microscopic dynamics in drying films and coatings
in a very reactive way and with a high dynamic range. We call this technique
"Adaptive Speckle Imaging Interferometry". We introduce an efficient tool, the
inter-image distance, to evaluate the speckle dynamics, and the concept of
"speckle rate" (SR, in Hz) to quantify this dynamics. The adaptive algorithm
plots a simple kinetics, the time evolution of the SR, providing a non-invasive
characterization of drying phenomena. A new commercial instrument, called
HORUS(R), based on ASII and specialized in the analysis of film formation and
drying processes is presented.


title: Structure and organization in inclusion-containing bilayer membranes

abstract:
  Membrane organization is essential for cellular functions such as signal
transduction and membrane trafficking. A major challenge is to understand the
lateral heterogeneous structures in membranes and membrane fluidity in the
presence of inclusions. Based on a considerable amount of experimental evidence
for lateral organization of lipid membranes which share astonishingly similar
features in the presence of different inclusions, we first present a general
model system of bilayer membranes embedded by nanosized inclusions, and explain
experimental findings. Here, the hydrophobic inclusions are simple models of
intrinsic membrane proteins, cholesterol embedded in the membrane, hydrophobic
drugs, or other nanoparticles for bio-medical applications. It is found that
lipid/inclusion-rich raft domains are formed at moderate inclusion
concentrations, and disappear with the increase of inclusions. At high
inclusion content, chaining of inclusions occurs due to the effective
attraction between inclusions mediated by lipids. Meanwhile, increasing
inclusions can also cause thickening of the membrane, and the distribution of
inclusions undergoes a layering transition from one-layer located in the
bilayer midplane to two-layer structure arranged into the two leaflets of a
bilayer. Our theoretical predictions address the complex interactions between
membranes and inclusions, suggesting a unifying mechanism which reflects the
competition between the conformational entropy of lipids favoring the formation
of lipid-rich rafts and the steric repulsion of inclusions leading to the
uniform dispersion.


title: Entanglement Entropy in Quantum Gravity and the Plateau Problem

abstract:
  In a quantum gravity theory the entropy of entanglement $S$ between the
fundamental degrees of freedom spatially divided by a surface is discussed. The
classical gravity is considered as an emergent phenomenon and arguments are
presented that: 1) $S$ is a macroscopical quantity which can be determined
without knowing a real microscopical content of the fundamental theory; 2) $S$
is given by the Bekenstein-Hawking formula in terms of the area of a
co-dimension 2 hypesurface $\cal B$; 3) in static space-times $\cal B$ can be
defined as a minimal hypersurface of a least volume separating the system in a
constant time slice. It is shown that properties of $S$ are in agreement with
basic properties of the von Neumann entropy. Explicit variational formulae for
$S$ in different physical examples are considered.


title:
Conditional Linearizability Criteria for Scalar Fourth Order Semi-Linear
  Ordinary Differential Equations

abstract:
  Using geometric methods for linearizing systems of second order cubically
semi-linear ordinary differential equations and third order quintically
semi-linear ordinary differential equations, we extend to the fourth order by
differentiating the third order equation. This yields criteria for
linearizability of a class of fourth order semi-linear ordinary differential
equations, which have not been discussed in the literature previously. It is
shown that the procedure can be extended to higher order. Though the results
for the higher orders are complicated, they are doable by algebraic computing.
The standard Lie approach, as developed at present does not seem to be amenable
to giving results that can be handled even by algebraic computing.


title:
Spectral Spatial Fluctuations of CMBR: Strategy and Concept of the
  Experiment

abstract:
  Spectral Spatial Fluctuations (SSF) of the Cosmic Microwave Background
Radiation (CMBR) temperature are considered as a result of an interaction of
primordial atoms and molecules with CMBR in proto-objects moving with peculiar
velocities relative to the CMBR. Expected optimistic values of $\Delta T/T$ are
2x10^{-5}--2x10^{-6}$ for SSF caused by HeH$^+$ at z =20-30 which are possible
redshifts of early reionization scenario. The bandwidth of the lines is 0.1-2%
depending on the scale of proto-objects and redshifts. For the SSF search CMBR
maps in different spectral channels are to be observed and then processed by
the Difference method. Simulation of the experiment is made for MSRT (Tuorla
Observatory, Finland) equipped with a 7x4 beam cryo-microbolometer array with a
chopping flat and frequency multiplexer providing up to 7 spectral channels in
each beam (88-100 GHz). Expected $\Delta $T/T limit in the experiment is 2x10
$^{-5}$ with 6'-7' angular and 2% frequency resolution. Simulation shows that
SSF may be recognized in the angular power spectrum when S/N in single
frequency CMBR maps is as small as 1.17 or even something less for white noise.
Such an experiment gives us a possibility to set upper limit of SSF in MM band
and prepare future SSF observations.


title: Forster mechanism of electron-driven proton pump

abstract:
  We examine a simple model of proton pumping through the inner membrane of
mitochondria in the living cell. We demonstrate that the pumping process can be
described using approaches of condensed matter physics. In the framework of
this model, we show that the resonant F\"orster-type energy exchange due to
electron-proton Coulomb interaction can provide an unidirectional flow of
protons against an electrochemical proton gradient, thereby accomplishing
proton pumping. The dependence of this effect on temperature as well as
electron and proton voltage build-ups are obtained taking into account
electrostatic forces and noise in the environment. We find that the proton pump
works with maximum efficiency in the range of temperatures and transmembrane
electrochemical potentials which correspond to the parameters of living cells.


title:
Comment on ``Phase Transitions in Systems of Self-Propelled Agents and
  Related Network Models''

abstract:
  In this comment we show that the transition to collective motion in
Vicsek-like systems with angular noise remain discontinuous for large velocity
values. Thus, the networks studied by Aldana {\et al.} [Phys. Rev. Lett. {\bf
98}, 095702 (2007)] at best constitute a singular, large velocity limit of
these systems.


title:
Dynamic aspects of individual design activities. A cognitive ergonomics
  viewpoint

abstract:
  This paper focuses on the use of knowledge possessed by designers. Data
collection was based on observations (by the cognitive ergonomics researcher)
and simultaneous verbalisations (by the designers) in empirical studies
conducted in the context of industrial design projects. The contribution of
this research is typical of cognitive ergonomics, in that it provides data on
actual activities implemented by designers in their actual work situation
(rather than on prescribed and/or idealised processes and methods). Data
presented concern global strategies (the way in which designers actually
organise their activity) and local strategies (reuse in design). Results from
cognitive ergonomics and other research that challenges the way in which people
are supposed to work with existing systems are generally not received warmly.
Abundant corroboration of such results is required before industry may consider
taking them into account. The opportunistic organisation of design activity is
taken here as an example of this reluctance. The results concerning this aspect
of design have been verified repeatedly, but only prototypes and experimental
systems implementing some of the requirements formulated on their basis, are
under development.


title:
Designing as Construction of Representations: A Dynamic Viewpoint in
  Cognitive Design Research

abstract:
  This article presents a cognitively oriented viewpoint on design. It focuses
on cognitive, dynamic aspects of real design, i.e., the actual cognitive
activity implemented by designers during their work on professional design
projects. Rather than conceiving de-signing as problem solving - Simon's
symbolic information processing (SIP) approach - or as a reflective practice or
some other form of situated activity - the situativity (SIT) approach - we
consider that, from a cognitive viewpoint, designing is most appropriately
characterised as a construction of representations. After a critical discussion
of the SIP and SIT approaches to design, we present our view-point. This
presentation concerns the evolving nature of representations regarding levels
of abstraction and degrees of precision, the function of external
representations, and specific qualities of representation in collective design.
Designing is described at three levels: the organisation of the activity, its
strategies, and its design-representation construction activities (different
ways to generate, trans-form, and evaluate representations). Even if we adopt a
"generic design" stance, we claim that design can take different forms
depending on the nature of the artefact, and we propose some candidates for
dimensions that allow a distinction to be made between these forms of design.
We discuss the potential specificity of HCI design, and the lack of cognitive
design research occupied with the quality of design. We close our discussion of
representational structures and activities by an outline of some directions
regarding their functional linkages.


title:
Recovering the mass and the charge of a Reissner-Nordstr\"om black hole
  by an inverse scattering experiment

abstract:
  In this paper, we study inverse scattering of massless Dirac fields that
propagate in the exterior region of a Reissner-Nordstr\"om black hole. Using a
stationary approach we determine precisely the leading terms of the high-energy
asymptotic expansion of the scattering matrix that, in turn, permit us to
recover uniquely the mass of the black hole and its charge up to a sign.


title: A Zoll counterexample to a geodesic length conjecture

abstract:
  We construct a counterexample to a conjectured inequality L<2D, relating the
diameter D and the least length L of a nontrivial closed geodesic, for a
Riemannian metric on the 2-sphere. The construction relies on Guillemin's
theorem concerning the existence of Zoll surfaces integrating an arbitrary
infinitesimal odd deformation of the round metric. Thus the round metric is not
optimal for the ratio L/D.


title:
An algebraic and graph theoretical framework to study monomial dynamical
  systems over a finite field

abstract:
  An n dimensional monomial dynamical system over a finite field K is a
nonlinear deterministic time discrete dynamical system with the property that
each of the n component functions is a monic nonzero monomial function in n
variables. In this paper we provide an algebraic and graph theoretic framework
to study the dynamic properties of monomial dynamical systems over a finite
field. Within this framework, characterization theorems for fixed point systems
(systems in which all trajectories end in steady states) are proved. In
particular, we present an algorithm of polynomial complexity to test whether a
given monomial dynamical system over a finite field is a fixed point system.
Furthermore, theorems that complement previous work are presented and
alternative proofs to previous results are supplied.


title: Optimizing Latency and Reliability of Pipeline Workflow Applications

abstract:
  Mapping applications onto heterogeneous platforms is a difficult challenge,
even for simple application patterns such as pipeline graphs. The problem is
even more complex when processors are subject to failure during the execution
of the application. In this paper, we study the complexity of a bi-criteria
mapping which aims at optimizing the latency (i.e., the response time) and the
reliability (i.e., the probability that the computation will be successful) of
the application. Latency is minimized by using faster processors, while
reliability is increased by replicating computations on a set of processors.
However, replication increases latency (additional communications, slower
processors). The application fails to be executed only if all the processors
fail during execution. While simple polynomial algorithms can be found for
fully homogeneous platforms, the problem becomes NP-hard when tackling
heterogeneous platforms. This is yet another illustration of the additional
complexity added by heterogeneity.


title:
Wide-Field Survey of Globular Clusters in M31. II. Kinematics of the
  Globular Cluster System

abstract:
  We present a kinematic analysis of the globular cluster(GC) system in M31.
Using the photometric and spectroscopic database of 504 GCs, we have
investigated the kinematics of the M31 GC system. We find that the all GC
system shows strong rotation, with rotation amplitude of v_rot~190km/s, and
that a weak rotation persists even for the outermost samples at |Y|>5kpc. The
rotation-corrected velocity dispersion for the GC system is estimated to be
sigma_{p,r}~130km/s, and it increases from sigma_{p,r}~120km/s at |Y|<1kpc to
sigma_{p,r}~150km/s at |Y|>5kpc. These results are very similar to those for
the metal-poor GCs. This shows that there is a dynamically hot halo in M31 that
is rotating but primarily pressure-supported. We have identified 50
"friendless" GCs, and they appear to rotate around the major axis of M31. For
the subsamples of metal-poor and metal-rich GCs, we have found that the
metal-rich GCs are more centrally concentrated than the metal-poor GCs, and
both subsamples show strong rotation. For the subsamples of bright and faint
GCs, it is found that the rotation for the faint GCs is stronger than that for
the bright GCs. We have identified 56 GCs and GC candidates with X-ray
detection. It is found that the majority of X-ray emitting GCs follow the disk
rotation, and that the redder, more metal-rich, and brighter GCs are more
likely to be detected as X-ray emitting GCs. We have derived a rotation curve
of M31 using the GCs at |Y|<0.6kpc. We have estimated the dynamical mass of M31
using `Projected Mass Estimator(PME)' and `Tracer Mass Estimator(TME)'. We
finally discuss the implication of these results and compare the kinematics of
GCs with that of planetary nebulae in M31.


title:
Estimating the number of negative eigenvalues of a relativistic
  Hamiltonian with regular magnetic field

abstract:
  We prove the analog of the Cwickel-Lieb-Rosenblum estimation for the number
of negative eigenvalues of a relativistic Hamiltonian with magnetic field $B\in
C^\infty_{\rm{pol}}(\mathbb R^d)$ and an electric potential $V\in
L^1_{\rm{loc}}(\mathbb R^d)$, $V_-\in L^d(\mathbb R^d)\cap L^{d/2}(\mathbb
R^d)$. Compared to the nonrelativistic case, this estimation involves both
norms of $V_-$ in $L^{d/2}(\mathbb R^d)$ and in $L^{d}(\mathbb R^d)$. A direct
consequence is a Lieb-Thirring inequality for the sum of powers of the absolute
values of the negative eigenvalues.


title: HI power spectrum of the spiral galaxy NGC628

abstract:
  We have measured the HI power spectrum of the nearly face-on spiral galaxy
NGC628 (M74) using a visibility based estimator. The power spectrum is well
fitted by a power law $P(U)=AU^{\alpha}$, with $\alpha =- 1.6\pm0.2$ over the
length scale $800 {\rm pc} {\rm to} 8 {\rm kpc}$. The slope is found to be
independent of the width of the velocity channel. This value of the slope is a
little more than one in excess of what has been seen at considerably smaller
length scales in the Milky-Way, Small Magellanic Cloud (LMC), Large Magellanic
Cloud (SMC) and the dwarf galaxy DDO210. We interpret this difference as
indicating a transition from three dimensional turbulence at small scales to
two dimensional turbulence in the plane of the galaxy's disk at length scales
larger than galaxy's HI scale height.
  The slope measured here is similar to that found at large scales in the LMC.
Our analysis also places an upper limit to the galaxy's scale height at $800\
{\rm pc}$ .


title: A theory of web traffic

abstract:
  We analyze access statistics of several popular webpages for a period of
several years. The graphs of daily downloads are highly non-homogeneous with
long periods of low activity interrupted by bursts of heavy traffic. These
bursts are due to avalanches of blog entries, referring to the page. We
quantitatively explain this behavior using the theory of branching processes.
We extrapolate these findings to construct a model of the entire web. According
to the model, the competition between webpages for viewers pushes the web into
a self-organized critical state. In this regime, the most interesting webpages
are in a near-critical state, with a power law distribution of traffic
intensity.