title: BOUT++: a framework for parallel plasma fluid simulations

abstract:
  A new modular code called BOUT++ is presented, which simulates 3D fluid
equations in curvilinear coordinates. Although aimed at simulating Edge
Localised Modes (ELMs) in tokamak X-point geometry, the code is able to
simulate a wide range of fluid models (magnetised and unmagnetised) involving
an arbitrary number of scalar and vector fields, in a wide range of geometries.
Time evolution is fully implicit, and 3rd-order WENO schemes are implemented.
Benchmarks are presented for linear and non-linear problems (the Orszag-Tang
vortex) showing good agreement. Performance of the code is tested by scaling
with problem size and processor number, showing efficient scaling to thousands
of processors.
  Linear initial-value simulations of ELMs using reduced ideal MHD are
presented, and the results compared to the ELITE linear MHD eigenvalue code.
The resulting mode-structures and growth-rate are found to be in good agreement
(BOUT++ = 0.245, ELITE = 0.239). To our knowledge, this is the first time
dissipationless, initial-value simulations of ELMs have been successfully
demonstrated.


title: Non procedural language for parallel programs

abstract:
  Probably building non procedural languages is the most prospective way for
parallel programming just because non procedural means no fixed way for
execution. The article consists of 3 parts. In first part we consider formal
systems for definition a named datasets and studying an expression power of
different subclasses. In the second part we consider a complexity of algorithms
of building sets by the definitions. In third part we consider a fullness and
flexibility of the class of program based data set definitions.


title:
Magnetic resonance in the model high-temperature superconductor
  HgBa$_2$CuO$_{4+\delta}$

abstract:
  We present an inelastic neutron scattering study of the structurally simple
single-layer compound HgBa$_2$CuO$_{4+\delta}$ close to optimal doping ($T_c
\approx 96$ K). A well-defined antiferromagnetic resonance with energy
$\omega_r = 56$ meV ($\approx 6.8 k_BT_c$) is observed below the
superconducting transition temperature $T_c$. The resonance mode is
energy-resolution limited and exhibits an intrinsic momentum width of about
$0.2 \mathrm{\mathring{A}^{-1}}$, consistent with prior work on several other
cuprates. However, the unusually large value of the mode energy implies a
non-universal relationship between $\omega_r$ and $T_c$ across different
families of cuprates.


title: Period and index of genus one curves over number fields

abstract:
  The period of a curve is the smallest positive degree of Galois-invariant
divisor classes. The index is the smallest positive degree of rational
divisors. We construct examples of genus one curves with prescribed period and
index over certain number fields.


title: Protein Microarrays with Carbon Nanotubes as Multi-Color Raman Labels

abstract:
  Detection of biomolecules is important in proteomics and clinical diagnosis
and treatment of diseases. Here, we apply functionalized, macromolecular,
single walled carbon nanotubes SWNTs as multi-color Raman labels to protein
arrays for highly sensitive, multiplexed protein detection. Raman detection
utilizes the sharp peaks of SWNTs with minimal background interference,
affording a high signal to noise ratio needed for ultra-sensitive detection.
Surface-enhanced Raman scattering SERS combined with the strong resonance Raman
intensity of SWNTs, affords detection sensitivity down to 1 fM, a three order
of magnitude improvement over most of reported fluorescence-based protein
detections. We show that human autoantibodies to Proteinase 3 aPR3, a biomarker
for the autoimmune disease Wegeners granulomatosis, is detected by Raman in
human serum up to a 107 dilution. Moreover, SWNT Raman tags are stable against
photobleaching and quenching, and by conjugating different antibodies to pure
12C and 13C SWNT isotopes, we demonstrate two-color SWNT Raman-based protein
detection in a multiplexed fashion.


title: PAMELA Positron Excess as a Signal from the Hidden Sector

abstract:
  The recent positron excess observed in the PAMELA satellite experiment
strengthens previous experimental findings. We give here an analysis of this
excess in the framework of the Stueckelberg extension of the standard model
which includes an extra $U(1)_X$ gauge field and matter in the hidden sector.
Such matter can produce the right amount of dark matter consistent with the
WMAP constraints. Assuming the hidden sector matter to be Dirac fermions it is
shown that their annihilation can produce the positron excess with the right
positron energy dependence seen in the HEAT, AMS and the PAMELA experiments.
Further test of the proposed model can come at the Large Hadron Collider. The
predictions of the $\bar p/p$ flux ratio also fit the data.


title: Number of wireless sensors needed to detect a wildfire

abstract:
  The lack of extensive research in the application of inexpensive wireless
sensor nodes for the early detection of wildfires motivated us to investigate
the cost of such a network. As a first step, in this paper we present several
results which relate the time to detection and the burned area to the number of
sensor nodes in the region which is protected. We prove that the probability
distribution of the burned area at the moment of detection is approximately
exponential, given that some hypotheses hold: the positions of the sensor nodes
are independent random variables uniformly distributed and the number of sensor
nodes is large. This conclusion depends neither on the number of ignition
points nor on the propagation model of the fire.


title: Hadronic matrix elements for TAUOLA: 3 pi and KKpi channels

abstract:
  We emphasize that the motivation for including our hadronic matrix elements
in TAUOLA is not only theoretical. We also show that our expressions describe
better the tau to 3pi ALEPH data and are able to fit BABAR data on the
isovector component of e^+e^- -> KKpi. The theoretical foundations of our
framework are the large-N_C limit of QCD, the chiral structure exhibited at low
energies and the proper asymptotic behaviour, ruled by QCD, that is demanded to
the associated form factors.


title:
Threshold and Flavour Effects in the Renormalization Group Equations of
  the MSSM II: Dimensionful couplings

abstract:
  We re-examine the one-loop renormalization group equations (RGEs) for the
dimensionful parameters of the minimal supersymmetric Standard Model with
broken supersymmetry, allowing for arbitrary flavour structure of the soft SUSY
breaking (SSB) parameters. We include threshold effects by evaluating the
$\beta$-functions in a sequence of (non-supersymmetric) effective theories with
heavy particles decoupled at the scale of their mass. We present the most
general form for high scale SSB parameters that obtains if we assume that the
supersymmetry breaking mechanism does not introduce new inter-generational
couplings. This form, possibly amended to allow additional sources of
flavour-violation, serves as a boundary condition for solving the RGEs for the
dimensionful MSSM parameters. We then present illustrative examples of
numerical solutions to the RGEs. We find that in a SUSY GUT with the scale of
SUSY scalars split from that of gauginos and higgsinos, the gaugino mass
unification condition may be violated by ${\cal O}$(10%). As another
illustration, we show that in mSUGRA, the rate for the flavour-violating
$\tilde{t}_1\to c\tilde{Z}_1$ decay obtained using the complete RGE solution is
smaller than that obtained using the commonly-used "single-step" integration of
the RGEs by a factor 10-25, and so may qualitatively change expectations for
topologies from top-squark pair production at colliders. Together with the RGEs
for dimensionless couplings presented in a companion paper, the RGEs in
Appendix B of this paper form a complete set of one-loop MSSM RGEs that include
threshold and flavour-effects necessary for two-loop accuracy.


title: Local energy estimate on Kerr black hole backgrounds

abstract:
  We study dispersive properties for the wave equation in the Kerr space-time
with small angular momentum. The main result of thispaper is to establish
uniform energy bounds and local energy decay for such backgrounds.


title: E10 and Gauged Maximal Supergravity

abstract:
  We compare the dynamics of maximal three-dimensional gauged supergravity in
appropriate truncations with the equations of motion that follow from a
one-dimensional E10/K(E10) coset model at the first few levels. The constant
embedding tensor, which describes gauge deformations and also constitutes an
M-theoretic degree of freedom beyond eleven-dimensional supergravity, arises
naturally as an integration constant of the geodesic model. In a detailed
analysis, we find complete agreement at the lowest levels. At higher levels
there appear mismatches, as in previous studies. We discuss the origin of these
mismatches.


title: The Universal Kaehler Modulus in Warped Compactifications

abstract:
  We construct the effective theory of the universal Kaehler modulus in warped
compactifications using the Hamiltonian formulation of general relativity. The
spacetime dependent 10d solution is constructed at the linear level for both
the volume modulus and its axionic partner, and nontrivial cancellations of
warping effects are found in the dimensional reduction. Our main result is that
the Kaehler potential is not corrected by warping, up to an overall shift in
the background value of the volume modulus. We extend the analysis beyond the
linearized approximation by computing the fully backreacted 10d metric
corresponding to a finite volume modulus fluctuation. Also, we discuss the
behavior of the modulus in strongly warped regions and show that there are no
mixings with light Kaluza-Klein modes. These results are important for the
phenomenology and cosmology of flux compactifications.


title: Spontaneous decay of a metastable domain wall

abstract:
  We consider the decay of a metastable domain wall. The transition proceeds
through quantum tunneling, and we calculate in arbitrary number of dimensions
the preexponential factor multiplying the leading semiclassical exponential
expression for the rate of the process. We find that the effect of the motion
in transverse directions reduces to a renormalization of the tension of the
edge of the wall in the semiclassical exponent. This behavior is similar to the
one previously found for breaking of a metastable string. However this simple
property is generally lost for spontaneous decay of higher-dimensional branes.


title:
From Multi-Keyholes to Measure of Correlation and Power Imbalance in
  MIMO Channels: Outage Capacity Analysis

abstract:
  An information-theoretic analysis of a multi-keyhole channel, which includes
a number of statistically independent keyholes with possibly different
correlation matrices, is given. When the number of keyholes or/and the number
of Tx/Rx antennas is large, there is an equivalent Rayleigh-fading channel such
that the outage capacities of both channels are asymptotically equal. In the
case of a large number of antennas and for a broad class of fading
distributions, the instantaneous capacity is shown to be asymptotically
Gaussian in distribution, and compact, closed-form expressions for the mean and
variance are given. Motivated by the asymptotic analysis, a simple,
full-ordering scalar measure of spatial correlation and power imbalance in MIMO
channels is introduced, which quantifies the negative impact of these two
factors on the outage capacity in a simple and well-tractable way. It does not
require the eigenvalue decomposition, and has the full-ordering property. The
size-asymptotic results are used to prove Telatar's conjecture for
semi-correlated multi-keyhole and Rayleigh channels. Since the keyhole channel
model approximates well the relay channel in the amplify-and-forward mode in
certain scenarios, these results also apply to the latter


title: The Scalar Meson f0(980) in Heavy-Meson Decays

abstract:
  A phenomenological analysis of the scalar meson f0(980) is performed that
relies on the quasi-two body decays D and Ds -> f0(980)P, with P=pi, K. The
two-body branching ratios are deduced from experimental data on D or Ds -> pi
pi pi, K Kbar pi and from the f0(980) -> pi+ pi- and f0(980) -> K+ K- branching
fractions. Within a covariant quark model, the scalar form factors F0(q2) for
the transitions D and Ds -> f0(980) are computed. The weak D decay amplitudes,
in which these form factors enter, are obtained in the naive factorization
approach assuming a quark-antiquark state for the scalar and pseudoscalar
mesons. They allow to extract information on the f0(980) wave function in terms
of u-ubar, d-dbar and s-sbar pairs as well as on the mixing angle between the
strange and non-strange components. The weak transition form factors are
modeled by the one-loop triangular diagram using two different relativistic
approaches: covariant light-front dynamics and dispersion relations. We use the
information found on the f0(980) structure to evaluate the scalar and vector
form factors in the transitions D and Ds -> f0(980), as well as to make
predictions for B and Bs -> f0(980), for the entire kinematically allowed
momentum range of q2.


title: An algebraic approach to laying a ghost to rest

abstract:
  In the recent literature there has been a resurgence of interest in the
fourth-order field-theoretic model of Pais-Uhlenbeck \cite {Pais-Uhlenbeck 50
a}, which has not had a good reception over the last half century due to the
existence of {\em ghosts} in the properties of the quantum mechanical solution.
Bender and Mannheim \cite{Bender 08 a} were successful in persuading the
corresponding quantum operator to `give up the ghost'. Their success had the
advantage of making the model of Pais-Uhlenbeck acceptable to the physical
community and in the process added further credit to the cause of advancement
of the use of ${\cal PT} $ symmetry. We present a case for the acceptance of
the Pais-Uhlenbeck model in the context of Dirac's theory by providing an
Hamiltonian which is not quantum mechanically haunted. The essential point is
the manner in which a fourth-order equation is rendered into a system of
second-order equations. We show by means of the method of reduction of order
\cite {Nucci} that it is possible to construct an Hamiltonian which gives rise
to a satisfactory quantal description without having to abandon Dirac.


title: R-axion detection at LHC

abstract:
  Supersymmetric models with spontaneously broken approximate R-symmetry
contain a light spin 0 particle, the R-axion. The properties of the particle
can be a powerful probe of the structure of the new physics. In this paper, we
discuss the possibilities of the R-axion detection at the LHC experiments. It
is challenge to observe this light particle in the LHC environment. However,
for typical values in which the mass of the R-axion is a few hundred MeV, we
show that those particles can be detected by searching for displaced vertices
from R-axion decay.


title: Secular Evolution of HD 12661: A System Caught at an Unlikely Time

abstract:
  The eccentricity evolution of multiple planet systems can provide valuable
constraints on planet formation models. Unfortunately, the inevitable
uncertainties in the current orbital elements can lead to significant
ambiguities in the nature of the secular evolution. Integrating any single set
of orbital elements inadequately describes the full range of secular evolutions
consistent with current observations. Thus, we combine radial velocity
observations of HD 12661 with Markov Chain Monte Carlo sampling to generate
ensembles of initial conditions for direct n-body integrations. We find that
any mean motion resonances are quite weak and do not significantly impact the
secular evolution, and that current observations indicate circulation or large
amplitude libration of the periapses. The eccentricity of the outer planet
undergoes large oscillations for nearly all of the allowed two-planet orbital
solutions. This type of secular evolution would arise if planet c had been
impulsively perturbed, perhaps due to strong scattering of an additional planet
that was subsequently accreted onto the star. Finally, we note that the secular
evolution implied by the current orbital configuration implies that planet c
spends ~96% of the time following an orbit more eccentric than that presently
observed. Either this system is being observed during a relatively rare state,
or additional planets are affecting the observed radial velocities and/or the
system's secular eccentricity evolution.


title:
A Second Case of Variable Na I D Lines in a Highly-Reddened Type Ia
  Supernova (with Erratum)

abstract:
  (Original) Recent high-resolution spectra of the Type Ia SN 2006X have
revealed the presence of time-variable and blueshifted Na I D features,
interpreted by Patat et al. as originating in circumstellar material within the
progenitor system. The variation seen in SN 2006X induces relatively large
changes in the total Na I D equivalent width ($\Delta\rm{EW}\approx 0.5
\unicode{x212B}$ in just over two weeks), that would be detectable at lower
resolutions. We have used a large data set comprising 2400 low-resolution
spectra of 450 Type Ia supernovae (SNe Ia) obtained by the CfA Supernova
Program to search for variable Na I D features. Out of the 31 SNe Ia (including
SN 2006X) in which we could have detected similar EW variations, only one other
(SN 1999cl) shows variable Na I D features, with an even larger change over a
similar ~10-day timescale ($\Delta\rm{EW} = 1.66 \pm 0.21 \unicode{x212B}$).
Interestingly, both SN 1999cl and SN 2006X are the two most highly-reddened
objects in our sample, raising the possibility that the variability is
connected to dusty environments.
  (Erratum) The large variation in the Na I D equivalent width observed in SN
1999cl results in fact from a measurement error. Our new measurements show that
the EW variation is significantly lower, at $0.43 \pm 0.14 \unicode{x212B}$.
While the EW variation remains statistically significant (3.1$\sigma$ different
from zero), it is now below the detection threshold of 0.5 $\unicode{x212B}$
derived from the Monte Carlo simulations published in the original paper. As a
result, SN 1999cl should no longer be considered as an object displaying
variable Na I D lines in our study. The fraction of SNe Ia in our sample
displaying Na I D lines thus goes from $\sim$6% (2/31) in the original study to
$\sim$3% (1/31) in the revised analysis, SN 2006X being the only SN Ia in our
sample with variable Na I D lines.


title:
The Optical Variability of the Quasar 3C~279: The Signature of a
  Decelerating Jet?

abstract:
  A recent optical monitoring campaign on the prominent quasar 3C279 revealed a
period of a remarkably clean exponential decay of BVRI fluxes with time, with a
time constant of 12.8 d, over about 14 days. This is clearly too long to be
associated with radiative cooling. Here we propose that this may be the
signature of deceleration of the synchrotron emitting jet component. We develop
a model analogous to the relativistic blast wave model for GRBs, including
radiative energy losses and radiation drag, to simulate the deceleration of a
relativistically moving plasmoid in the moderately dense AGN environment.
Synchrotron, SSC and external Compton emission are evaluated self-consistently.
We show that the observed optical light curve decay can be successfully
reproduced with this model. The decelerating plasmoid model predicts a delayed
X-ray flare, about 2 - 3 weeks after the onset of the quasi-exponential light
curve decay in the optical. A robust prediction of this model, which can be
tested with Fermi and simultaneous optical monitoring, is that the peak in the
gamma-ray light curve at ~ 100 MeV is expected to be delayed by a few days with
respect to the onset of the optical decay, while the VHE gamma-rays are
expected to track the optical light curve closely with a delay of at most a few
hours.


title:
The Atomic to Molecular Transition in Galaxies. II: HI and H_2 Column
  Densities

abstract:
  Gas in galactic disks is collected by gravitational instabilities into giant
atomic-molecular complexes, but only the inner, molecular parts of these
structures are able to collapse to form stars. Determining what controls the
ratio of atomic to molecular hydrogen in complexes is therefore a significant
problem in star formation and galactic evolution. In this paper we use the
model of H_2 formation, dissociation, and shielding developed in the previous
paper in this series to make theoretical predictions for atomic to molecular
ratios as a function of galactic properties. We find that the molecular
fraction in a galaxy is determined primarily by its column density and
secondarily by its metallicity, and is to good approximation independent of the
strength of the interstellar radiation field. We show that the column of atomic
hydrogen required to shield a molecular region against dissociation is ~10 Msun
pc^-2 at solar metallicity. We compare our model to data from recent surveys of
the Milky Way and of nearby galaxies, and show that the both the primary
dependence of molecular fraction on column density and the secondary dependence
on metallicity that we predict are in good agreement with observed galaxy
properties.


title: Star Formation in the rho Ophiuchi Molecular Cloud

abstract:
  A review of star formation in the Rho Ophiuchi molecular complex is
presented, with particular emphasis on studies of the main cloud, L1688, since
1991. Recent photometric and parallax measurements of stars in the Upper
Scorpius subgroup of the Sco-Cen OB association suggest a distance for the
cloud between 120 and 140 parsecs. Star formation is ongoing in the dense cores
of L1688 with a median age for young stellar objects of 0.3 Myr. The surface
population appears to have a median age of 2-5 Myr and merges with low mass
stars in the Upper Scorpius subgroup. Making use of the most recent X-ray and
infrared photometric surveys and spectroscopic surveys of L1688, we compile a
list of over 300 association members with counterparts in the 2MASS catalog.
Membership criteria, such as lithium absorption, X-ray emission, and infrared
excess, cover the full range of evolutionary states for young stellar objects.
Spectral energy distributions are classified for many association members using
infrared photometry obtained from the Spitzer Space Telescope.


title: Atmospheric Escape from Hot Jupiters

abstract:
  Photoionization heating from UV radiation incident on the atmospheres of hot
Jupiters may drive planetary mass loss. We construct a model of escape that
includes realistic heating and cooling, ionization balance, tidal gravity, and
pressure confinement by the host star wind. We show that mass loss takes the
form of a hydrodynamic ("Parker") wind, emitted from the planet's dayside
during lulls in the stellar wind. When dayside winds are suppressed by the
confining action of the stellar wind, nightside winds might pick up if there is
sufficient horizontal transport of heat. A hot Jupiter loses mass at maximum
rates of ~2 x 10^12 g/s during its host star's pre-main-sequence phase and ~2
x10^10 g/s during the star's main sequence lifetime, for total maximum losses
of ~0.06% and ~0.6% of the planet's mass, respectively. For UV fluxes F_UV <
10^4 erg/cm^2/s, the mass loss rate is approximately energy-limited and is
proportional to F_UV^0.9. For larger UV fluxes, such as those typical of T
Tauri stars, radiative losses and plasma recombination force the mass loss rate
to increase more slowly as F_UV^0.6. Dayside winds are quenched during the T
Tauri phase because of confinement by overwhelming stellar wind pressure. We
conclude that while UV radiation can indeed drive winds from hot Jupiters, such
winds cannot significantly alter planetary masses during any evolutionary
stage. They can, however, produce observable signatures. Candidates for
explaining why the Lyman-alpha photons of HD 209458 are absorbed at
Doppler-shifted velocities of +/- 100 km/s include charge-exchange in the shock
between the planetary and stellar winds.


title: Large gaps between random eigenvalues

abstract:
  We show that in the point process limit of the bulk eigenvalues of
$\beta$-ensembles of random matrices, the probability of having no eigenvalue
in a fixed interval of size $\lambda$ is given by \[\bigl(\
kappa_{\beta}+o(1)\bigr)\lambda^{\gamma_{\beta}}\exp\biggl(-{\bet
a}{64}\lambda^2+\biggl({\beta}{8}-{1}{4}\biggr)\lambda\biggr)\] as
$\lambda\to\infty$, where
\[\gamma_{\beta}={1}{4}\biggl({\beta}{2}+{2}{\beta}-3\biggr)\] and
$\kappa_{\beta}$ is an undetermined positive constant. This is a slightly
corrected version of a prediction by Dyson [J. Math. Phys. 3 (1962) 157--165].
Our proof uses the new Brownian carousel representation of the limit process,
as well as the Cameron--Martin--Girsanov transformation in stochastic calculus.


title:
Kolmogorov-Smirnov test as a tool to study the distribution of
  ultra-high energy cosmic ray sources

abstract:
  We analyze in detail the two-dimensional Kolmogorov-Smirnov test as a tool to
learn about the distribution of the sources of the ultra-high energy cosmic
rays. We confront in particular models based on AGN observed in X rays, on
galaxies observed in HI and isotropic distributions, discussing how this method
can be used not only to reject isotropy but also to support or reject specific
source models, extending results obtained recently in the literature.


title:
Revisiting the Global Electroweak Fit of the Standard Model and Beyond
  with Gfitter

abstract:
  The global fit of the Standard Model to electroweak precision data, routinely
performed by the LEP electroweak working group and others, demonstrated
impressively the predictive power of electroweak unification and quantum loop
corrections. We have revisited this fit in view of (i) the development of the
new generic fitting package Gfitter, (ii) the insertion of constraints from
direct Higgs searches at LEP and the Tevatron, and (iii) a more thorough
statistical interpretation of the results. Gfitter is a modular fitting
toolkit, which features predictive theoretical models as independent plugins,
and a statistical analysis of the fit results using toy Monte Carlo techniques.
The state-of-the-art electroweak Standard Model is fully implemented, as well
as generic extensions to it. This paper introduces the Gfitter project, and
presents state-of-the-art results for the global electroweak fit in the
Standard Model, and for a model with an extended Higgs sector (2HDM). Numerical
and graphical results for fits with and without including the constraints from
the direct Higgs searches at LEP and Tevatron are given. Perspectives for
future colliders are analysed and discussed. Including the direct Higgs
searches, we find M_H=(116.4 +18.3 -1.3) GeV, and the 2sigma and 3sigma allowed
regions [114,145] GeV and [[113,168] and [180,225]] GeV, respectively. For the
strong coupling strength at fourth perturbative order we obtain
alpha_S(M_Z)=0.1193 +0.0028 -0.0027(exp) +- 0.0001(theo). Finally, for the mass
of the top quark, excluding the direct measurements, we find m_t=(178.2 +9.8
-4.2) GeV. In the 2HDM we exclude a charged-Higgs mass below 240 GeV at 95%
confidence level. This limit increases towards larger tan(beta), where e.g.,
M_H+-<780 GeV is excluded for tan(beta)=70.


title:
Incoherent Landau-Zener-Stuckelberg Transitions in Single-Molecule
  Magnets

abstract:
  It is shown that in experiments on single molecule magnets (SMM's) in which
transitions between two lowest spin states are induced by sweeping the applied
magnetic field along the easy axis, the transitions are fully incoherent.
Nuclear spins and the dipolar coupling of molecular spins are identified as the
main sources of decoherence, and the form of the decoherence is calculated. The
Landau-Zener-Stuckelberg (LZS) process is examined in light of this
decoherence, and it is shown that the correct formula for the spin-flip
probability is better given by a more recent formula of Kayanuma's than that of
LZS. The two formulas are shown to be identical in the limit of rapid sweeps.
An approximate way of incorporating the molecular spin dipole field into the
rate equations for this process is developed.


title:
NMSSM in disguise: discovering singlino dark matter with soft leptons at
  the LHC

abstract:
  We suggest an NMSSM scenario, motivated by dark matter constraints, that may
disguise itself as a much simpler mSUGRA scenario at the LHC. We show how its
non-minimal nature can be revealed, and the bino--singlino mass difference
measured, by looking for soft leptons.


title:
Parallel-propagated frame along null geodesics in higher-dimensional
  black hole spacetimes

abstract:
  In [arXiv:0803.3259] the equations describing the parallel transport of
orthonormal frames along timelike (spacelike) geodesics in a spacetime
admitting a non-degenerate principal conformal Killing-Yano 2-form h were
solved. The construction employed is based on studying the Darboux subspaces of
the 2-form F obtained as a projection of h along the geodesic trajectory. In
this paper we demonstrate that, although slightly modified, a similar
construction is possible also in the case of null geodesics. In particular, we
explicitly construct the parallel-transported frames along null geodesics in
D=4,5,6 Kerr-NUT-(A)dS spacetimes. We further discuss the parallel transport
along principal null directions in these spacetimes. Such directions coincide
with the eigenvectors of the principal conformal Killing-Yano tensor. Finally,
we show how to obtain a parallel-transported frame along null geodesics in the
background of the 4D Plebanski-Demianski metric which admits only a conformal
generalization of the Killing-Yano tensor.


title:
Effect of microwave radiation on non-linear resistivity of a
  two-dimensional electron gas at large filling factors

abstract:
  We study transport properties of a two-dimensional electron gas, placed in a
classically strong perpendicular magnetic field and in constant and oscillating
in-plane electric fields. The analysis is based on a quantum Boltzmann equation
derived for a weakly disordered two-dimensional electron gas. We consider
disordered potential with both long and short range correlations. Electron
scattering off such disorder is not limited to small change in momentum
direction, but occurs on an arbitrary angle, including the backscattering. The
non-linearity of the transport in the considered system is a consequence of two
co-existing effects: formation of a non-equilibrium distribution function of
electrons and modification of the scattering rate off the disorder in the
presence of dc and ac electric fields. This work describes both effects in a
unified way. The calculated dissipative component of electric current
oscillates as a function of the electric field strength and frequency of
microwave radiation in a qualitative agreement with experiments.


title:
Astrophysical S factor for the radiative capture 12N(p,gamma)13O
  determined from the 14N(12N,13O)13C proton transfer reaction

abstract:
  The cross section of the radiative proton capture reaction on the drip line
nucleus 12N was investigated using the Asymptotic Normalization Coefficient
(ANC) method. We have used the 14N(12N,13O)13C proton transfer reaction at 12
MeV/nucleon to extract the ANC for 13O -> 12N + p and calculate from it the
direct component of the astrophysical S factor of the 12N(p,gamma)13O reaction.
The optical potentials used and the DWBA analysis of the proton transfer
reaction are discussed. For the entrance channel, the optical potential was
inferred from an elastic scattering measurement carried out at the same time
with the transfer measurement. From the transfer, we determined the square of
the ANC, C^2(13Og.s.) = 2.53 +/- 0.30 fm-1, and hence a value of 0.33(4) keVb
was obtained for the direct astrophysical S factor at zero energy. Constructive
interference at low energies between the direct and resonant captures leads to
an enhancement of Stotal(0) = 0.42(5) keVb. The 12N(p,gamma)13O reaction was
investigated in relation to the evolution of hydrogen-rich massive Population
III stars, for the role that it may play in the hot pp-chain nuclear burning
processes, possibly occurring in such objects.


title:
Perspectives for coherent optical formation of strontium molecules in
  their electronic ground state

abstract:
  Optical Feshbach resonances [Phys. Rev. Lett. 94, 193001 (2005)] and
pump-dump photoassociation with short laser pulses [Phys. Rev. A 73, 033408
(2006)] have been proposed as means to coherently form stable ultracold alkali
dimer molecules. In an optical Feshbach resonance, the intensity and possibly
frequency of a cw laser are ramped up linearly followed by a sudden switch-off
of the laser. This is applicable to tightly trapped atom pairs. In short-pulse
photoassociation, the pump pulse forms a wave-packet in an electronically
excited state. The ensuing dynamics carry the wave-packet to shorter
internuclear distances where, after half a vibrational period, it can be
deexcited to the electronic ground state by the dump pulse. Short-pulse
photoassociation is suited for both shallow and tight traps. The applicability
of these two means to produce ultracold molecules is investigated here for
$^{88}$Sr. Dipole-allowed transitions proceeding via the $B^1\Sigma_u^+$
excited state as well as transitions near the intercombination line are
studied.


title:
On the geometrical representation of the path integral reduction
  Jacobian: The case of dependent coordinates in the description of the reduced
  motion

abstract:
  The geometrical representation of the path integral reduction Jacobian
obtained in the problem of the path integral quantization of a scalar particle
motion on a smooth compact Riemannian manifold with the given free isometric
action of the compact semisimple Lie group has been found for the case when the
local reduced motion is described by means of dependent coordinates. The result
is based on the scalar curvature formula for the original manifold which is
viewed as a total space of the principal fibre bundle.


title:
On the Development and Applications of Automated Searches for Eclipsing
  Binary Stars

abstract:
  Eclipsing binary star systems provide the most accurate method of measuring
both the masses and radii of stars. Moreover, they enable testing tidal
synchronization and circularization theories, as well as constraining models of
stellar structure and dynamics. With the recent availability of large-scale
multi-epoch photometric datasets we were able to study eclipsing binary stars
en masse. In this thesis, we analyzed 185,445 light curves from ten TrES
fields, and 218,699 light curves from the OGLE II bulge fields. In order to
manage such large quantities of data, we developed a pipeline with which we
systematically identified eclipsing binaries, solved for their geometric
orientations, and then found their components' absolute properties. Following
this analysis we assembled catalogs of eclipsing binaries with their models,
computed statistical distributions of their properties, and located rare cases
for further follow-up, including T-Cyg1-03378, which has unusual eclipse timing
variations. Of particular importance are low-mass eclipsing binaries, which are
rare yet critical for resolving the ongoing mass-radius discrepancy between
theoretical models and observations. To this end, we have discovered over a
dozen new low-mass eclipsing binary candidates and spectroscopically confirmed
the masses of five of them. One of these confirmed candidates, T-Lyr1-17236, is
especially interesting because of its long orbital period. We examined
T-Lyr1-17236 in detail and found that it is consistent with the magnetic
disruption hypothesis. Both the source code of our pipeline and the complete
list of our candidates are freely available.


title: Fission decay of N = Z nuclei at high angular momentum: $^{60}$Zn

abstract:
  Using a unique two-arm detector system for heavy ions (the BRS, binary
reaction spectrometer) coincident fission events have been measured from the
decay of $^{60}$Zn compound nuclei formed at 88MeV excitation energy in the
reactions with $^{36}$Ar beams on a $^{24}$Mg target at $E_{lab}(^{36}$Ar) =
195 MeV. The detectors consisted of two large area position sensitive (x,y) gas
telescopes with Bragg-ionization chambers. From the binary coincidences in the
two detectors inclusive and exclusive cross sections for fission channels with
differing losses of charge were obtained. Narrow out-of-plane correlations
corresponding to coplanar decay are observed for two fragments emitted in
binary events, and in the data for ternary decay with missing charges from 4 up
to 8. After subtraction of broad components these narrow correlations are
interpreted as a ternary fission process at high angular momentum through an
elongated shape. The lighter mass in the neck region consists dominantly of two
or three-particles. Differential cross sections for the different mass splits
for binary and ternary fission are presented. The relative yields of the binary
and ternary events are explained using the statistical model based on the
extended Hauser-Feshbach formalism for compound nucleus decay. The ternary
fission process can be described by the decay of hyper-deformed states with
angular momentum around 45-52 $hbar$.


title:
Influence of aggregate size and volume fraction on shrinkage induced
  micro-cracking of concrete and mortar

abstract:
  In this paper, the influence of aggregate size and volume fraction on
shrinkage induced micro-cracking and permeability of concrete and mortar was
investigated. Nonlinear finite element analyses of model concrete and mortar
specimens with regular and random aggregate arrangements were performed. The
aggregate diameter was varied between 2 and 16 mm. Furthermore, a range of
volume fractions between 0.1 and 0.5 was studied. The nonlinear analyses were
based on a 2D lattice approach in which aggregates were simplified as monosized
cylindrical inclusions. The analysis results were interpreted by means of crack
length, crack width and change of permeability. The results show that
increasing aggregate diameter (at equal volume fraction) and decreasing volume
fraction (at equal aggregate diameter), increases crack width and consequently
greatly increases permeability.


title: The minimum stellar metallicity observable in the Galaxy

abstract:
  The first stars fundamentally transformed the early Universe through their
production of energetic radiation and the first heavy chemical elements. The
impact on cosmic evolution sensitively depends on their initial mass function
(IMF), which can be empirically constrained through detailed studies of
ancient, metal-poor halo stars in our Galaxy. We compare the lowest magnesium
and iron abundances measured in Galactic halo stars with theoretical
predictions for the minimum stellar enrichment provided by Population III stars
under the assumption of a top-heavy IMF. To demonstrate that abundances
measured in metal-poor stars reflect the chemical conditions at their
formation, and that they can thus be used to derive constraints on the
primordial IMF, we carry out a detailed kinematic analysis of a large sample of
metal-poor stars drawn from the SDSS survey. We assess whether interstellar
accretion has altered their surface abundances. We find that accretion is
generally negligible, even at the extremely low levels where the primordial IMF
can be tested. We conclude that the majority of the first stars were very
massive, but had likely masses below ~140 M.


title: N=4 Mechanics, WDVV Equations and Polytopes

abstract:
  N=4 superconformal n-particle quantum mechanics on the real line is governed
by two prepotentials, U and F, which obey a system of partial nonlinear
differential equations generalizing the Witten-Dijkgraaf-Verlinde-Verlinde
(WDVV) equation for F. The solutions are encoded by the finite Coxeter systems
and certain deformations thereof, which can be encoded by particular polytopes.
We provide A_n and B_3 examples in some detail. Turning on the prepotential U
in a given F background is very constrained for more than three particles and
nonzero central charge. The standard ansatz for U is shown to fail for all
finite Coxeter systems. Three-particle models are more flexible and based on
the dihedral root systems.


title:
Multi-Satellite Observations of Cygnus X-1 to Study the Focused Wind and
  Absorption Dips

abstract:
  High-mass X-ray binary systems are powered by the stellar wind of their donor
stars. The X-ray state of Cygnus X-1 is correlated with the properties of the
wind which defines the environment of mass accretion. Chandra-HETGS
observations close to orbital phase 0 allow for an analysis of the photoionzed
stellar wind at high resolution, but because of the strong variability due to
soft X-ray absorption dips, simultaneous multi-satellite observations are
required to track and understand the continuum, too. Besides an earlier joint
Chandra and RXTE observation, we present first results from a recent campaign
which represents the best broad-band spectrum of Cyg X-1 ever achieved: On 2008
April 18/19 we observed this source with XMM-Newton, Chandra, Suzaku, RXTE,
INTEGRAL, Swift, and AGILE in X- and gamma-rays, as well as with VLA in the
radio. After superior conjunction of the black hole, we detect soft X-ray
absorption dips likely due to clumps in the focused wind covering >95 % of the
X-ray source, with column densities likely to be of several 10^23 cm^-2, which
also affect photon energies above 20 keV via Compton scattering.


title: A note on the eigenvalues of double band matrices

abstract:
  We consider matrices containing two diagonal bands of positive entries. We
show that all eigenvalues of such matrices are of the form $r \zeta$, where $r$
is a nonnegative real number and $\zeta$ is a $p$th root of unity, where $p$ is
the period of the matrix, which is computed from the distance between the
bands.


title:
Search for neutral Higgs bosons at high tan(beta) in the
  b(h/H/A)->btautau channel

abstract:
  The first search in ppbar collisions at sqrt(s)=1.96 GeV for the production
of neutral Higgs bosons in association with bottom quarks and decaying in two
tau leptons is presented. The cross section for this process is enhanced in
many extensions of the Standard Model (SM), such as its minimal supersymmetric
extension (MSSM) at large tan(beta). The data, corresponding to an integrated
luminosity of 328 pb-1, were collected with the D0 detector at the Fermilab
Tevatron Collider. An upper limit is set on the production cross section of
neutral Higgs bosons in the mass range of 90 to 150 GeV, and this limit is used
to exclude part of the MSSM parameter space.


title: Quenched-Vacancy Induced Spin-Glass Order

abstract:
  The ferromagnetic phase of an Ising model in d=3, with any amount of quenched
antiferromagnetic bond randomness, is shown to undergo a transition to a
spin-glass phase under sufficient quenched bond dilution. This general result,
demonstrated here with the numerically exact renormalization-group solution of
a d=3 hierarchical lattice, is expected to hold true generally, for the cubic
lattice and for quenched site dilution. Conversely, in the
ferromagnetic-spinglass-antiferromagnetic phase diagram, the spin-glass phase
expands under quenched dilution at the expense of the ferromagnetic and
antiferromagnetic phases. In the ferro-spinglass phase transition induced by
quenched dilution reentrance is seen, as previously found for the
ferro-spinglass transition induced by increasing the antiferromagnetic bond
concentration.


title:
Long range order in the classical kagome antiferromagnet: effective
  Hamiltonian approach

abstract:
  Following Huse and Rutenberg [Phys. Rev. B 45, 7536 (1992)], I argue the
classical Heisenberg antiferromagnet on the kagom\'e lattice has long-range
spin order of the $\sqrt{3}\times\sqrt{3}$ type (modulo gradual orientation
fluctuations of the spins' plane). I start from the effective quartic
Hamiltonian for the soft (out of plane) spin fluctuation modes, and treat as a
perturbation those terms which depend on the discrete coplanar state. Soft mode
correlations, which become the coefficients of a discrete effective
Hamiltonian, are estimated analytically.


title: Detector decoy quantum key distribution

abstract:
  Photon number resolving detectors can enhance the performance of many
practical quantum cryptographic setups. In this paper, we employ a simple
method to estimate the statistics provided by such a photon number resolving
detector using only a threshold detector together with a variable attenuator.
This idea is similar in spirit to that of the decoy state technique, and is
specially suited for those scenarios where only a few parameters of the photon
number statistics of the incoming signals have to be estimated. As an
illustration of the potential applicability of the method in quantum
communication protocols, we use it to prove security of an entanglement based
quantum key distribution scheme with an untrusted source without the need of a
squash model and by solely using this extra idea. In this sense, this detector
decoy method can be seen as a different conceptual approach to adapt a single
photon security proof to its physical, full optical implementation. We show
that in this scenario the legitimate users can now even discard the double
click events from the raw key data without compromising the security of the
scheme, and we present simulations on the performance of the BB84 and the
6-state quantum key distribution protocols.


title:
Accelerated expansion of a universe containing a self-interacting
  Bose-Einstein gas

abstract:
  Acceleration of the universe is obtained from a model of non-relativistic
particles with a short-range attractive interaction, at low enough temperature
to produce a Bose-Einstein condensate. Conditions are derived for
negative-pressure behavior. In particular, we show that a phantom-accelerated
regime at the beginning of the universe solves the horizon problem,
consistently with nucleosynthesis.


title:
Cartan--Helgason theorem, Poisson transform, and Furstenberg--Satake
  compactifications

abstract:
  The connections between the objects mentioned in the title are used to give a
short proof of the Cartan--Helgason theorem and a natural construction of the
compactifications.


title: Asymptotic Positivity of Hurwitz Product Traces: Two Proofs

abstract:
  Consider the polynomial $tr (A + tB)^m$ in $t$ for positive hermitian
matrices $A$ and $B$ with $m \in \N$. The Bessis-Moussa-Villani conjecture (in
the equivalent form of Lieb and Seiringer) states that this polynomial has
nonnegative coefficients only. We prove that they are at least asymptotically
positive, for the nontrivial case of $AB \neq 0$. More precisely, we show -
once complex-analytically, once combinatorially - that the $k$-th coefficient
is positive for all integer $m \geq m_0$, where $m_0$ depends on $A$, $B$ and
$k$.


title: Riemannian metrics having common geodesics with Berwald metrics

abstract:
  In Theorem 1, we generalize the results of Szabo for Berwald metrics that are
not necessary strictly convex: we show that for every Berwald metric F there
always exists a Riemannian metric affine equivalent to F. As an application we
show (Corollary 3) that every Berwald projectively flat metric is a Minkowski
metric; this statement is a "Berwald" version of Hilbert's 4th problem.
  Further, we investigate geodesic equivalence of Berwald metrics. Theorem 2
gives a system of PDE that has a (nontrivial) solution if and only if the given
essentially Berwald metric admits a Riemannian metric that is (nontrivially)
geodesically equivalent to it. The system of PDE is linear and of
Cauchy-Frobenius type, i.e., the derivatives of unknown functions are explicit
expressions of the unknown functions.
  As an application (Corollary 2), we obtain that geodesic equivalence of an
essentially Berwald metric and a Riemannian metric is always affine equivalence
provided both metrics are complete.


title:
Alpha-particle optical potential proofs at astrophysically relevant
  energies

abstract:
  $(\alpha,\gamma)$ and $(\alpha$,n) reaction cross sections recently measured
close to the reaction thresholds are rather well described by a previously
developed regional optical potential. Thus, particular features of the
$\alpha$-particle optical potential at energies below the Coulomb barrier,
besides parameters describing $\alpha$-particle elastic scattering at higher
energies are confirmed. Additional limitations of similar statistical model
calculations for minor reaction channels are shown to be most likely due to an
overlooked process or critical values of statistical model parameters around
closed nuclear shells.


title: On thermal stability of topological qubit in Kitaev's 4D model

abstract:
  We analyse stability of the four-dimensional Kitaev model - a candidate for
scalable quantum memory - in finite temperature within the weak coupling
Markovian limit. It is shown that, below a critical temperature, certain
topological qubit observables X and Z possess relaxation times exponentially
long in the size of the system. Their construction involves polynomial in
system's size algorithm which uses as an input the results of measurements
performed on all individual spins. We also discuss the drawbacks of such
candidate for quantum memory and mention the implications of the stability of
qubit for statistical mechanics.


title:
Anisotropy, Itineracy, and Magnetic Frustration in High-Tc Iron
  Pnictides

abstract:
  Using first-principle density functional theory calculations combined with
insight from a tight-binding representation, dynamical mean field theory, and
linear response theory, we have extensively investigated the electronic
structures and magnetic interactions of nine ferropnictides representing three
different structural classes. The calculated magnetic interactions are found to
be short-range, and the nearest ($J_{1a}$) and next-nearest ($J_{2}$) exchange
constants follow the universal trend of J_{1a}/2J_{2}\sim 1, despite their
itinerant origin and extreme sensitivity to the z-position of As. These results
bear on the discussion of itineracy versus magnetic frustration as the key
factor in stabilizing the superconducting ground state. The calculated spin
wave dispersions show strong magnetic anisotropy in the Fe plane, in contrast
to cuprates.


title: Very Twisted Stable Maps

abstract:
  Let X be a smooth projective Deligne-Mumford stack over an algebraically
closed field k of characteristic 0. In this paper we construct the moduli stack
of very twisted stable maps, extending the notion of twisted stable maps by
Abramovich and Vistoli to allow for generic stabilizers on the source curves.
We also consider the Gromov-Witten theory given by this construction.


title: A sufficient condition for intrinsic knotting of bipartite graphs

abstract:
  We present evidence in support of a conjecture that a bipartite graph with at
least five vertices in each part and |E(G)| \geq 4 |V(G)| - 17 is intrinsically
knotted. We prove the conjecture for graphs that have exactly five or exactly
six vertices in one part. We also show that there is a constant C_n such that a
bipartite graph with exactly n \geq 5 vertices in one part and |E(G)| \geq 4
|V(G)| + C_n is intrinsically knotted. Finally, we classify bipartite graphs
with ten or fewer vertices with respect to intrinsic knotting.


title: A complexity dichotomy for hypergraph partition functions

abstract:
  We consider the complexity of counting homomorphisms from an $r$-uniform
hypergraph $G$ to a symmetric $r$-ary relation $H$. We give a dichotomy theorem
for $r>2$, showing for which $H$ this problem is in FP and for which $H$ it is
#P-complete. This generalises a theorem of Dyer and Greenhill (2000) for the
case $r=2$, which corresponds to counting graph homomorphisms. Our dichotomy
theorem extends to the case in which the relation $H$ is weighted, and the goal
is to compute the \emph{partition function}, which is the sum of weights of the
homomorphisms. This problem is motivated by statistical physics, where it
arises as computing the partition function for particle models in which certain
combinations of $r$ sites interact symmetrically. In the weighted case, our
dichotomy theorem generalises a result of Bulatov and Grohe (2005) for graphs,
where $r=2$. When $r=2$, the polynomial time cases of the dichotomy correspond
simply to rank-1 weights. Surprisingly, for all $r>2$ the polynomial time cases
of the dichotomy have rather more structure. It turns out that the weights must
be superimposed on a combinatorial structure defined by solutions of an
equation over an Abelian group. Our result also gives a dichotomy for a closely
related constraint satisfaction problem.


title:
Supernova Explosions and the Triggering of Galactic Fountains and
  Outflows

abstract:
  We review here the effects of supernovae (SNe) explosions on the environment
of star-forming galaxies. Randomly distributed, clustered SNe explosions cause
the formation of hot superbubbles that drive either galactic fountains or
supersonic winds out of the galactic disk. In a galactic fountain, the ejected
gas is re-captured by the gravitational potential and falls back onto the disk.
  From 3D non-equilibrium radiative cooling hydrodynamical simulations of these
fountains, we find that they may reach altitudes smaller than 5 kpc in the halo
and hence explain the formation of the so-called intermediate-velocity-clouds
(IVCs). On the other hand, the high-velocity-clouds (HVCs) that are observed at
higher altitudes (of up to 12 kpc) require another mechanism to explain their
production. We argue that they could be formed either by the capture of gas
from the intergalactic medium and/or by the action of magnetic fields that are
carried out to the halo with the gas in the fountains. Due to angular momentum
losses (of 10-15%) to the halo, we find that the fountain material falls back
to smaller radii and is not largely spread over the galactic disk, as
previously expected. This result is consistent with the metal distribution
derived from recent chemical models of the galaxy. We also find that after
about 150 Myr, the gas circulation between the halo and the disk in the
fountains reaches a steady state regime (abridged).


title: Control of spin injection by direct current in lateral spin valves

abstract:
  The spin injection and accumulation in metallic lateral spin valves with
transparent interfaces is studied using d.c. injection current. Unlike
a.c.-based techniques, this allows investigating the effects of the direction
and magnitude of the injected current. We find that the spin accumulation is
reversed by changing the direction of the injected current, whereas its
magnitude does not change. The injection mechanism for both current directions
is thus perfectly symmetric, leading to the same spin injection efficiency for
both spin types. This result is accounted for by a spin-dependent diffusion
model. Joule heating increases considerably the local temperature in the spin
valves when high current densities are injected ($\sim$80--105 K for
1--2$\times10^{7}$A cm$^{-2}$), strongly affecting the spin accumulation.


title: Inverse Optimization Techniques for Targeted Self-Assembly

abstract:
  This article reviews recent inverse statistical-mechanical methodologies that
we have devised to optimize interaction potentials in soft matter systems that
correspond to stable "target" structures. We are interested in finding the
interaction potential, not necessarily pairwise additive or spherically
symmetric, that stabilizes a targeted many-body system by generally
incorporating complete configurational information. Unlike previous work, our
primary interest is in the possible many-body structures that may be generated,
some of which may include interesting but known structures, while others may
represent entirely new structural motifs. Soft matter systems, such as colloids
and polymers, offer a versatile means of realizing the optimized interactions.
It is shown that these inverse approaches hold great promise for controlling
self-assembly to a degree that surpasses the less-than-optimal path that nature
has provided. Indeed, we envision being able to "tailor" potentials that
produce varying degrees of disorder, thus extending the traditional idea of
self-assembly to incorporate both amorphous and crystalline structures as well
as quasicrystals. The notion of tailoring potentials that correspond to
targeted structures is motivated by the rich fundamental statistical-mechanical
issues and questions offered by this fascinating inverse problem as well as our
recent ability to identify structures that have optimal bulk properties or
desirable performance characteristics. Recent results have already led to a
deeper basic understanding of the mathematical relationship between the
collective structural behavior of many-body systems and their interactions, as
well as optimized potentials that enable self-assembly of ordered and
disordered particle configurations with novel structural and bulk properties.


title: Quark-Novae, cosmic reionization, and early r-process element production

abstract:
  We examine the case for Quark-Novae (QNe) as possible sources for the
reionization and early metal enrichment of the universe. Quark-Novae are
predicted to arise from the explosive collapse (and conversion) of sufficiently
massive neutron stars into quark stars. A Quark-Nova (QN) can occur over a
range of time scales following the supernova event. For QNe that arise days to
weeks after the supernovae, we show that dual-shock that arises as the QN
ejecta encounter the supernova ejecta can produce enough photons to reionize
hydrogen in most of the Inter-Galactic medium (IGM) by z ~ 6. Such events can
explain the large optical depth tau_e ~ 0.1 as measured by WMAP, if the
clumping factor, C, of the material being ionized is smaller than 10. We
suggest a way in which a normal initial mass function (IMF) for the oldest
stars can be reconciled with a large optical depth as well as the mean
metallicity of the early IGM post reionization. We find that QN also make a
contribution to r-process element abundances for atomic numbers A > 130. We
predict that the main cosmological signatures of Quark-Novae are the gamma-ray
bursts that announce their birth. These will be clustered at redshifts in the
range z ~ 7-8 in our model.


title: Summation of Hyperharmonic Series

abstract:
  We shall show that the sum of the series formed by the so-called
hyperharmonic numbers can be expressed in terms of the Riemann zeta function.
More exactly, we give summation formula for the general hyperharmonic series.


title: About the Non-Integer Property of Hyperharmonic Numbers

abstract:
  It was proven in 1915 by Leopold Theisinger that the $H_n$ harmonic numbers
are never integers. In 1996 Conway and Guy have defined the concept of
hyperharmonic numbers. The question naturally arises: are there any integer
hyperharmonic numbers? The author gives a partial answer to this question and
conjectures that the answer is "no".


title: On the Harary-Kauffman Conjecture and Turk's Head Knots

abstract:
  The m,n Turk's Head Knot, THK(m,n), is an "alternating (m,n) torus knot." We
prove the Harary-Kauffman conjecture for all THK(m,n) except for the case where
m \geq 5 is odd and n \geq 3 is relatively prime to m. We also give evidence in
support of the conjecture in that case. Our proof rests on the observation that
none of these knots have prime determinant except for THK(m,2) when P_m is a
Pell prime.


title:
Cavity QED characterization of many-body atomic states in double-well
  potentials -- The role of dissipation

abstract:
  When an incident light beam is scattered off a sample of ultracold atoms
trapped in an optical lattice, the statistical properties of the
retro-reflected field contain information about the quantum state of the atoms,
and permit for example to distinguish between atoms in a superfluid and a Mott
insulator state. This paper extends our previous analysis of this problem to
include the effects of cavity damping. We use a Monte Carlo wave function
method to determine the two-time correlation function and time-dependent
physical spectrum of the retro-reflected field in the case of a simple two-well
lattice. We also analyze quantitatively the entanglement between the atoms and
the light field for atoms in a Mott insulator and a superfluid state.


title:
Effective Kbar N interaction with strong pi Sigma dynamics constrained
  by chiral SU(3) symmetry

abstract:
  We derive a single-channel effective Kbar N interaction from chiral SU(3)
coupled-channel dynamics, emphasizing the important role of the pi Sigma
channel and the structure of the Lambda(1405) resonance. The chiral low energy
theorem requires strongly attractive interaction not only in the Kbar N channel
but also in the pi Sigma channel. As a consequence of the strong pi Sigma
dynamics, the equivalent potential in single Kbar N channel turns out to be
less attractive than the one used in a purely phenomenological approach.


title: Effect of high pressure on multiferroic BiFeO3

abstract:
  We report experimental evidence for pressure instabilities in the model
multiferroic BiFeO3 and namely reveal two structural phase transitions around 3
GPa and 10 GPa by using diffraction and far-infrared spectroscopy at a
synchrotron source. The intermediate phase from 3 to 9 GPa crystallizes in a
monoclinic space group, with octahedra tilts and small cation displacements.
When the pressure is further increased the cation displacements (and thus the
polar character) of BiFeO3 is suppressed above 10 GPa. The above 10 GPa
observed non-polar orthorhombic Pnma structure is in agreement with recent
theoretical ab-initio prediction, while the intermediate monoclinic phase was
not predicted theoretically.


title: Conjectural Equilibrium in Water-filling Games

abstract:
  This paper considers a non-cooperative game in which competing users sharing
a frequency-selective interference channel selfishly optimize their power
allocation in order to improve their achievable rates. Previously, it was shown
that a user having the knowledge of its opponents' channel state information
can make foresighted decisions and substantially improve its performance
compared with the case in which it deploys the conventional iterative
water-filling algorithm, which does not exploit such knowledge. This paper
discusses how a foresighted user can acquire this knowledge by modeling its
experienced interference as a function of its own power allocation. To
characterize the outcome of the multi-user interaction, the conjectural
equilibrium is introduced, and the existence of this equilibrium for the
investigated water-filling game is proved. Interestingly, both the Nash
equilibrium and the Stackelberg equilibrium are shown to be special cases of
the generalization of conjectural equilibrium. We develop practical algorithms
to form accurate beliefs and search desirable power allocation strategies.
Numerical simulations indicate that a foresighted user without any a priori
knowledge of its competitors' private information can effectively learn the
required information, and induce the entire system to an operating point that
improves both its own achievable rate as well as the rates of the other
participants in the water-filling game.


title:
Can disk-magnetosphere interaction models and beat frequency models for
  quasi-periodic oscillation in accreting X-ray pulsars be reconciled?

abstract:
  In this paper we review some aspects of the theory of magnetic threaded
disks. We discuss in particular the equations that determine the position of
the inner disk boundary by using different prescriptions for the neutron
star-accretion disk interaction. We apply the results to several accretion
powered X-ray pulsars that showed both quasi-periodic oscillations in their
X-ray flux and spin-up/spin-down torque reversals. Under the hypothesis that
the beat-frequency model is applicable to the quasi-periodic oscillations, we
show that these sources provide an excellent opportunity to test models of the
disk-magnetosphere interaction. A comparison is carried out between the
magnetospheric radius obtained with all the prescriptions used in threaded disk
models; this shows that none of those prescriptions is able to reproduce the
combination of quasi-periodic oscillations and torque behaviour observed for
different X-ray luminosity levels in the X-ray pulsars in the present sample.
  This suggests that the problem of accretion disk threading by stellar
magnetic field is still lacking a comprehensive solution. We discuss briefly an
outline of possible future developments in this field.


title:
Efficient polarization entanglement concentration for electrons with
  charge detection

abstract:
  We present an entanglement concentration protocol for electrons based on
their spins and their charges. The combination of an electronic polarizing beam
splitter and a charge detector functions as a parity check device for two
electrons, with which the parties can reconstruct maximally entangled electron
pairs from those in a less-entanglement state nonlocally. This protocol has a
higher efficiency than those based on linear optics and it does not require the
parties to know accurately the information about the less-entanglement state,
which makes it more convenient in a practical application of solid quantum
computation and communication.


title: Can lattices in SL(n,R) act on the circle?

abstract:
  This expository paper describes the various methods that have yielded partial
results on the conjecture that if n > 2, then no lattice in SL(n,R) has a
faithful action on the circle (by homeomorphisms). Topics include amenability,
Kazhdan's property (T), bounded cohomology, bounded generation, and the
Reeb-Thurston Stability Theorem.


title:
Tensor interaction constraints from beta decay recoil spin asymmetry of
  trapped atoms

abstract:
  We have measured the angular distribution of recoiling daughter nuclei
emitted from the Gamow-Teller $\beta$ decay of spin-polarized $^{80}$Rb. The
asymmetry of this distribution vanishes to lowest order in the Standard Model
(SM) in pure Gamow-Teller decays, producing an observable very sensitive to new
interactions. We measure the non-SM contribution to the asymmetry to be
$A_{T}$= 0.015 $\pm$ 0.029 (stat) $\pm$ 0.019 (syst), consistent with the SM
prediction. We constrain higher-order SM corrections using the measured
momentum dependence of the asymmetry, and their remaining uncertainty dominates
the systematic error. Future progress in determining the weak magnetism term
theoretically or experimentally would reduce the final errors. We describe the
resulting constraints on fundamental 4-Fermi tensor interactions.


title: A search for high-mass resonances decaying to dimuons at CDF

abstract:
  We present a search for high-mass neutral resonances using dimuon data
corresponding to an integrated luminosity of 2.3 fb$^{-1}$ collected in {$p\bar
p$} collisions at {$\sqrt{s}$ = 1.96 TeV} by the CDF II detector at the
Fermilab Tevatron. No significant excess above the standard model expectation
is observed in the dimuon invariant-mass spectrum. We set 95% confidence level
upper limits on $\sigma \cdot BR (p \bar{p} \to X \to \mu \bar{\mu})$, where
$X$ is a boson with spin 0, 1, or 2. Using these cross section limits, we
determine lower mass limits on sneutrinos in R-parity-violating supersymmetric
models, $Z'$ bosons, and Kaluza-Klein gravitons in the Randall-Sundrum model.


title:
Vector Magnetic Fields and Electric Currents from the Imaging Vector
  Magnetograph

abstract:
  First, we describe a general procedure to produce high quality vector
magnetograms using the Imaging Vector Magnetograph (IVM) at Mees Solar
Observatory. At the spatial resolution 2"x2", the Stokes Q,U,V uncertainty
reaches 0.001-0.0005 in time-averaged data over 1-hour in the quiet Sun. When
vector magnetic fields are inferred from the time-averaged Stokes spectral
images of FeI 6302.5A, the resulting uncertainties are on the order of 10 G for
the longitudinal fields, 40 G for the transverse field strength and 9 degree
for the magnetic azimuth. The magnetic field inversion used in this work is the
"Triplet" code, which was developed and implemented in the IVM software package
by the late Barry J. LaBonte. The inversion code is described in detail in the
Appendix.
  Second, we solve for the absolute value of the vertical electric current
density, |Jz|, accounting for the above IVM problems, for two different active
regions. One is a single sunspot region (NOAA 10001 observed on 20 June 2002)
while the other is a more complex, quadrupolar region (NOAA10030 observed on 15
July 2002). We use a calculation that does not require disambiguation of 180
degree in the transverse field directions. The |Jz| uncertainty is on the order
of 7.0 mA m^-2. The vertical current density increases with increasing vertical
magnetic field. The rate of increase is about 1 -2 times as large in the
quadrupolar NOAA 10030 region as in the simple NOAA 10001, and it is more
spatially variable over NOAA 10030 than over NOAA 10001.


title:
Possible mechanisms for initiating macroscopic left-right asymmetry in
  developing organisms

abstract:
  How might systematic left-right (L/R) asymmetry of the body plan originate in
multicellular animals (and plants)? Somehow, the microscopic handedness of
biological molecules must be brought up to macroscopic scales. Basic symmetry
principles suggest that the usual "biological" mechanisms -- diffusion and gene
regulation -- are insufficient to implement the "right-hand rule" defining a
third body axis from the other two. Instead, on the cellular level, "physical"
mechanisms (forces and collective dynamic states) are needed involving the long
stiff fibers of the cytoskeleton. I discuss some possible scenarios; only in
the case of vertebrate internal organs is the answer currently known (and even
that is in dispute).


title: On the Exel crossed product of topological covering maps

abstract:
  For dynamical systems defined by a covering map of a compact Hausdorff space
and the corresponding transfer operator, the associated crossed product
$C^*$-algebras $\cros$ introduced by Exel and Vershik are considered. An
important property for homeomorphism dynamical systems is topological freeness.
It can be extended in a natural way to in general non-invertible dynamical
systems generated by covering maps. In this article, it is shown that the
following four properties are equivalent: the dynamical system generated by a
covering map is topologically free; the canonical imbedding of $C(X)$ into
$\cros$ is a maximal abelian $C^*$-subalgebra of $\cros$; any nontrivial two
sided ideal of $\cros$ has non-zero intersection with the imbedded copy of
$C(X)$; a certain natural representation of $\cros$ is faithful. This result is
a generalization to non-invertible dynamics of the corresponding results for
crossed product $C^*$-algebras of homeomorphism dynamical systems.


title:
The Sub-parsec Scale Radio Properties of Southern Starburst Galaxies.
  II. Supernova Remnants, the Supernova Rate, and the Ionised Medium in the NGC
  4945 Starburst

abstract:
  Wide-field VLBI observations of the nearby starburst galaxy NGC 4945,
obtained with the Australian LBA, have produced 2.3 GHz images over two epochs
with a maximum spatial resolution of 0.3 pc. 15 sources were detected, 13 of
which correspond to sources identified in higher frequency (3 cm and 12 mm)
ATCA images. Four of the sources are resolved into shell-like structures
ranging between 1.1 to 2.1 pc in diameter. From these data the spectra of 13
compact radio sources in NGC 4945 were modelled; nine were found to be
consistent with free-free absorbed power laws and four with a simple power law
spectrum. The free-free opacity is highest toward the nucleus but varies
significantly throughout the nuclear region, implying that the overall
structure of the ionised medium is clumpy. Of the 13 sources, 10 have steep
intrinsic spectra associated with synchrotron emission from supernova remnants,
the remaining sources have flat intrinsic spectra which may be associated with
thermal radio emission. A non-thermal source with a jet-like morphology is
detected ~1" from the assumed location of the AGN. A type II supernova (SN)
rate upper limit of 15.3/yr is determined for the inner 250 pc region of the
galaxy at the 95% confidence level, based on the lack of detection of new
sources in observations spanning 1.9 years and a simple model for the evolution
of supernova remnants. A type II SN rate of >0.1(v/1e4)/yr is implied from
estimates of supernova remnant source counts, sizes and expansion rates, where
v is the radial expansion velocity of the supernova remnant in km/s. A SFR of
2.4(v/1e4)<SFR(M>=5Msun)<370 Msun/yr has been estimated directly from the SN
rate limits and is of the same order of magnitude as rates determined from
integrated FIR and radio luminosities.


title: Product-type non-commutative polynomial states

abstract:
  In math/0702157, arXiv:0712.4185, we investigated monic multivariate
non-commutative orthogonal polynomials, their recursions, states of
orthogonality, and corresponding continued fraction expansions. In this note,
we collect a number of examples, demonstrating what these general results look
like for the most important states on non-commutative polynomials, namely for
various product states. In particular, we introduce a notion of a product-type
state on polynomials, which covers all the non-commutative universal products
and excludes some other familiar non-commutative products, and which guarantees
a number of nice properties for the corresponding polynomials.


title: Photovoltage in curved 1D systems

abstract:
  Curvature of quantum wire results in intrasubband absorption of
  IR radiation that induces stationary photovoltage in presence of circular
polarization. This effect is studied in ballistic (collisionless) and kinetic
regimes. The consideration is concentrated on quantum wires with curved central
part. It is shown, that if mean free path is shorter than length of the curved
part the photovoltage does not depend on the wire shape, but on the total angle
of rotation of wire tangent. It is not the case when mean free path is finite
or large. This situation was studied for three specific shapes of wires: "hard
angle", "open book" and "$\Omega$-like".


title:
Optical photometry and spectroscopy of the type Ibn supernova SN 2006jc
  until the onset of dust formation

abstract:
  We present optical UBVRI photometric and spectroscopic data of the type Ibn
supernova SN 2006jc, until the onset of the dust forming phase. The optical
spectrum shows a blue continuum and is dominated by the presence of moderately
narrow (velocity ~2500 km/s) He I emission lines superimposed over a relatively
weak supernova spectrum. The helium lines are produced in a pre-existing He
rich circumstellar shell. The observed helium line fluxes indicate the
circumstellar shell is dense, with a density of ~10^9 - 10^{10} cm^{-3}. The
helium mass in this shell is estimated to be <~0.07 Msun. The optical light
curves show a clear signature of dust formation, indicated by a sharp decrease
in the magnitudes around day 50, accompanied by a reddening of the colours. The
evolution of the optical light curves during the early phase and that of the
uvoir bolometric light curve at all phases is reasonably similar to normal Ib/c
supernovae.


title:
Feedback Stabilization Methods for the Numerical Solution of Systems of
  Ordinary Differential Equations

abstract:
  In this work we study the problem of step size selection for numerical
schemes, which guarantees that the numerical solution presents the same
qualitative behavior as the original system of ordinary differential equations,
by means of tools from nonlinear control theory. Lyapunov-based and Small-Gain
feedback stabilization methods are exploited and numerous illustrating
applications are presented for systems with a globally asymptotically stable
equilibrium point. The obtained results can be used for the control of the
global discretization error as well.


title: The complex Lorentzian Leech lattice and the bimonster (II)

abstract:
  Let $D$ be the incidence graph of the projective plane over $\FF_3$. The
Artin group of the graph $D$ maps onto the bimonster and a complex hyperbolic
reflection group $\Gamma$ acting on 13 dimensional complex hyperbolic space
$Y$. The generators of the Artin group are mapped to elements of order 2 (resp.
3) in the bimonster (resp. $\Gamma$). Let $Y^{\circ} \subseteq Y$ be the
complement of the union of the mirrors of $\Gamma$. Daniel Allcock has
conjectured that the orbifold fundamental group of $Y^{\circ}/\Gamma$ surjects
onto bimonster. In this article we study the reflection group $\Gamma$. Our
main result shows that there is homomorphism from the Artin group of $D$ to the
orbifold fundamental group of $Y^{\circ}/\Gamma$, obtained by sending the Artin
generators to the generators of monodromy around the mirrors of the generating
reflections in $\Gamma$. This answers a question in Allcock's article "A
monstrous proposal" and takes a step towards the proof of Allcock's conjecture.
The finite group $\op{PGL}(3, \FF_3) \subseteq \Aut(D)$ acts on $Y$ and fixes a
complex hyperbolic line pointwise. We show that the restriction of
$\Gamma$-invariant meromorphic automorphic forms on $Y$ to the complex
hyperbolic line fixed by $\op{PGL}(3, \FF_3)$ gives meromorphic modular forms
of level 13.


title: A variant of Wiener's attack on RSA

abstract:
  Wiener's attack is a well-known polynomial-time attack on a RSA cryptosystem
with small secret decryption exponent d, which works if d<n^{0.25}, where n=pq
is the modulus of the cryptosystem. Namely, in that case, d is the denominator
of some convergent p_m/q_m of the continued fraction expansion of e/n, and
therefore d can be computed efficiently from the public key (n,e).
  There are several extensions of Wiener's attack that allow the RSA
cryptosystem to be broken when d is a few bits longer than n^{0.25}. They all
have the run-time complexity (at least) O(D^2), where d=Dn^{0.25}. Here we
propose a new variant of Wiener's attack, which uses results on Diophantine
approximations of the form |\alpha - p/q| < c/q^2, and "meet-in-the-middle"
variant for testing the candidates (of the form rq_{m+1} + sq_m) for the secret
exponent. This decreases the run-time complexity of the attack to O(D log(D))
(with the space complexity O(D)).


title:
Calculation of the Norm of the Error Functional of Optimal Quadrature
  Formulas in the Space $W_2^{(2,1)}(0,1)$

abstract:
  In this paper in the space $W_2^{(2,1)}(0,1)$ square of the norm of the error
functional of a optimal quadrature formula is calculated.


title:
Structural Transitions in A Crystalline Bilayer : The Case of Lennard
  Jones and Gaussian Core Models

abstract:
  We study structural transitions in a system of interacting particles arranged
as a crystalline bilayer, as a function of the density $\rho$ and the distance
$d$ between the layers. As $d$ is decreased a sequence of transitions involving
triangular, rhombic, square and centered rectangular lattices is observed. The
sequence of phases and the order of transitions depends on the nature of
interactions.


title: Scalar invariants in gravitational and electromagnetic fields

abstract:
  The paper discusses some scalar invariants in the gravitational field and
electromagnetic field by means of the characteristics of the quaternions. When
we emphasize some definitions of quaternion physical quantities, the speed of
light, mass density, energy density, power density, charge density, and spin
magnetic moment density etc. will remain the same respectively in the
gravitational and electromagnetic fields under the coordinate transformation.
The results explain why there are some relationships among different invariants
in the gravitational and electromagnetic fields.


title: Einstein metrics and GIT stability

abstract:
  In this expository article we review the problem of finding Einstein metrics
on compact K\"ahler manifolds and Sasaki manifolds. In the former half of this
article we see that, in the K\"ahler case, the problem fits better with the
notion of stability in Geometric Invariant Theory if we extend the problem to
that of finding extremal K\"ahler metrics or constant scalar curvature K\"ahler
(cscK) metrics. In the latter half of this paper we see that most of ideas in
K\"ahler geometry extend to Sasaki geometry as transverse K\"ahler geometry. We
also summarize recent results about the existence of toric Sasaki-Einstein
metrics.


title: Chaplygin electron gas model

abstract:
  We provide a new electromagnetic mass model admitting Chaplygin gas equation
of state. We investigate three specializations, the first characterized by a
vanishing effective pressure, the second provided with a constant effective
density and the third is described by a constant effective pressure. For these
specializations two particular cases are discussed. In addition, for
specialization I, case I we found isotropic coordinate as well as Kretschmann
scalar, and for specialization III, case II two special scenarios have been
studied.


title:
Peculiar nature of hard X-ray eclipse in SS433 from INTEGRAL
  observations

abstract:
  The analysis of INTEGRAL observations (2003-2008) of superaccreting galactic
microquasar SS433 at precessional phases with the maximum disk opening angle is
carried out. The shape and width of the primary X-ray eclipse is found to be
strongly variable suggesting additional absorption in dense stellar wind and
gas outflows from the optical A7I-component. The joint modeling of X-ray
eclipse and precessional X-ray variability by a geometrical model suggests the
binary mass ratio q=m_x/m_v=0.3, allowing an explnation of peculiarities of the
optical variability of SS433, in particular, the substantial precessional
variability at the primary optical eclipse minimum. For the mass function of
the optical star f_v=0.268 M_\odot as derived from Hillwig and Gies (2008)
data, the obtained q yields the masses of the components m_x=5 M_\odot, m_v=15
M_\odot, confirming the black hole nature of the relativistic object in SS433.
The independence of the observed hard X-ray spectrum on the precession phase
suggests that hard X-ray emission is formed in an extended hot corona. The
Monte-Carlo simulations of the broadband X-ray spectrum of SS433 at the maximum
disk opening precessional phases allowed us to determine physical parameters of
the corona (temperature T_{cor}=20 keV, Thomson optical depth \tau=0.2), and to
estimate the jet mass outflow rate \dot M_j=3\times 10^{19} g/s yielding the
kinetic power of the jets \sim 10^{39} erg/s.


title: Aleph-zero-categorical groups and their completions

abstract:
  We embed a countably categorical group G into a locally compact group c(G)
with a non-trivial topology and study how topological properties of c(G) are
connected with the structure of definable subgroups of G.


title: Conversion/Preference Games

abstract:
  We introduce the concept of Conversion/Preference Games, or CP games for
short. CP games generalize the standard notion of strategic games. First we
exemplify the use of CP games. Second we formally introduce and define the
CP-games formalism. Then we sketch two `real-life' applications, namely a
connection between CP games and gene regulation networks, and the use of CP
games to formalize implied information in Chinese Wall security. We end with a
study of a particular fixed-point construction over CP games and of the
resulting existence of equilibria in possibly infinite games.


title:
Generalization of l1 constraints for high dimensional regression
  problems

abstract:
  We focus on the high dimensional linear regression
$Y\sim\mathcal{N}(X\beta^{*},\sigma^{2}I_{n})$, where
$\beta^{*}\in\mathds{R}^{p}$ is the parameter of interest. In this setting,
several estimators such as the LASSO and the Dantzig Selector are known to
satisfy interesting properties whenever the vector $\beta^{*}$ is sparse.
Interestingly both of the LASSO and the Dantzig Selector can be seen as
orthogonal projections of 0 into
$\mathcal{DC}(s)=\{\beta\in\mathds{R}^{p},\|X'(Y-X\beta)\|_{\infty}\leq s\}$ -
using an $\ell_{1}$ distance for the Dantzig Selector and $\ell_{2}$ for the
LASSO. For a well chosen $s>0$, this set is actually a confidence region for
$\beta^{*}$. In this paper, we investigate the properties of estimators defined
as projections on $\mathcal{DC}(s)$ using general distances. We prove that the
obtained estimators satisfy oracle properties close to the one of the LASSO and
Dantzig Selector. On top of that, it turns out that these estimators can be
tuned to exploit a different sparsity or/and slightly different estimation
objectives.


title:
Room Temperature Ferromagnetic Semiconductor Rutile Ti1-xCoxO2-\delta
  Epitaxial Thin Films Grown by Sputtering Method

abstract:
  Room temperature ferromagnetic semiconductor rutile Ti1-xCoxO2-\delta (101)
epitaxial thin films were grown on r-sapphire substrates by a dc sputtering
method. Ferromagnetic magnetization, magnetic circular dichroism, and anomalous
Hall effect were clearly observed at room temperature in sputter-grown films
for the first time. The magnetization value is nearly as large as 3\mu B/Co
that is consistent with the high spin state Co2+ in this compound recently
established by spectroscopic methods. Consequently, its originally large
magneto-optical response is further enhanced.


title: Logical tools for handling change in agent-based systems

abstract:
  We give a unified approach to various results and problems of nonclassical
logics


title: Defeasible inheritance systems and reactive diagrams

abstract:
  We give an analysis of defeasible inheritance diagrams, also from the
perspective of reactive diagrams.


title: Galois groups over function fields of positive characteristic

abstract: We describe examples motivated by the work of Serre and Abhyankar.


title:
Approximation of a Fractional Order System by an Integer Order Model
  Using Particle Swarm Optimization Technique

abstract:
  System identification is a necessity in control theory. Classical control
theory usually considers processes with integer order transfer functions. Real
processes are usually of fractional order as opposed to the ideal integral
order models. A simple and elegant scheme is presented for approximation of
such a real world fractional order process by an ideal integral order model. A
population of integral order process models is generated and updated by PSO
technique, the fitness function being the sum of squared deviations from the
set of observations obtained from the actual fractional order process. Results
show that the proposed scheme offers a high degree of accuracy.


title:
A Swarm Intelligence Based Scheme for Complete and Fault-tolerant
  Identification of a Dynamical Fractional Order Process

abstract:
  System identification refers to estimation of process parameters and is a
necessity in control theory. Physical systems usually have varying parameters.
For such processes, accurate identification is particularly important. Online
identification schemes are also needed for designing adaptive controllers. Real
processes are usually of fractional order as opposed to the ideal integral
order models. In this paper, we propose a simple and elegant scheme of
estimating the parameters for such a fractional order process. A population of
process models is generated and updated by particle swarm optimization (PSO)
technique, the fitness function being the sum of squared deviations from the
actual set of observations. Results show that the proposed scheme offers a high
degree of accuracy even when the observations are corrupted to a significant
degree. Additional schemes to improve the accuracy still further are also
proposed and analyzed.


title:
The Application of Stochastic Optimization Algorithms to the Design of a
  Fractional-order PID Controller

abstract:
  The Proportional-Integral-Derivative Controller is widely used in industries
for process control applications. Fractional-order PID controllers are known to
outperform their integer-order counterparts. In this paper, we propose a new
technique of fractional-order PID controller synthesis based on peak overshoot
and rise-time specifications. Our approach is to construct an objective
function, the optimization of which yields a possible solution to the design
problem. This objective function is optimized using two popular bio-inspired
stochastic search algorithms, namely Particle Swarm Optimization and
Differential Evolution. With the help of a suitable example, the superiority of
the designed fractional-order PID controller to an integer-order PID controller
is affirmed and a comparative study of the efficacy of the two above algorithms
in solving the optimization problem is also presented.


title:
A Deterministic Model for Analyzing the Dynamics of Ant System Algorithm
  and Performance Amelioration through a New Pheromone Deposition Approach

abstract:
  Ant Colony Optimization (ACO) is a metaheuristic for solving difficult
discrete optimization problems. This paper presents a deterministic model based
on differential equation to analyze the dynamics of basic Ant System algorithm.
Traditionally, the deposition of pheromone on different parts of the tour of a
particular ant is always kept unvarying. Thus the pheromone concentration
remains uniform throughout the entire path of an ant. This article introduces
an exponentially increasing pheromone deposition approach by artificial ants to
improve the performance of basic Ant System algorithm. The idea here is to
introduce an additional attracting force to guide the ants towards destination
more easily by constructing an artificial potential field identified by
increasing pheromone concentration towards the goal. Apart from carrying out
analysis of Ant System dynamics with both traditional and the newly proposed
deposition rules, the paper presents an exhaustive set of experiments performed
to find out suitable parameter ranges for best performance of Ant System with
the proposed deposition approach. Simulations reveal that the proposed
deposition rule outperforms the traditional one by a large extent both in terms
of solution quality and algorithm convergence. Thus, the contributions of the
article can be presented as follows: i) it introduces differential equation and
explores a novel method of analyzing the dynamics of ant system algorithms, ii)
it initiates an exponentially increasing pheromone deposition approach by
artificial ants to improve the performance of algorithm in terms of solution
quality and convergence time, iii) exhaustive experimentation performed
facilitates the discovery of an algebraic relationship between the parameter
set of the algorithm and feature of the problem environment.


title: Adequacy of Link Families

abstract:
  Using computer calculations and working with representatives of pretzel
tangles we established general adequacy criteria for different classes of knots
and links. Based on adequate graphs obtained from all Kauffman states of an
alternating link we defined a new numerical invariant: adequacy number, and
computed adequacy polynomial which is the invariant of alternating link
families. Adequacy polynomial distinguishes (up to mutation) all families of
alternating knots and links whose generating link has at most $n=12$ crossings.


title:
Quantum random number generator based on the photon number decision of
  weak laser pulses

abstract:
  We propose an approach to realize a quantum random number generator (QRNG)
based on the photon number decision of weak laser pulses. This type of QRNG can
generate true random numbers at a high speed and can be adjusted to zero bias
conveniently, thus is suitable for the applications in quantum cryptography.


title:
Tuning PID and FOPID Controllers using the Integral Time Absolute Error
  Criterion

abstract:
  Particle swarm optimization (PSO) is extensively used for real parameter
optimization in diverse fields of study. This paper describes an application of
PSO to the problem of designing a fractional-order
proportional-integral-derivative (FOPID) controller whose parameters comprise
proportionality constant, integral constant, derivative constant, integral
order (lambda) and derivative order (delta). The presence of five optimizable
parameters makes the task of designing a FOPID controller more challenging than
conventional PID controller design. Our design method focuses on minimizing the
Integral Time Absolute Error (ITAE) criterion. The digital realization of the
deigned system utilizes the Tustin operator-based continued fraction expansion
scheme. We carry out a simulation that illustrates the effectiveness of the
proposed approach especially for realizing fractional-order plants. This paper
also attempts to study the behavior of fractional PID controller vis-a-vis that
of its integer order counterpart and demonstrates the superiority of the former
to the latter.


title:
Symmetry and reciprocity constraints on diffraction by gratings of
  quasi-planar particles

abstract:
  Symmetry and reciprocity constraints on polarization state of the field
diffracted by gratings of quasi-planar particles are considered. It is shown
that the optical activity effects observed recently in arrays of quasi-planar
plasmonic particles on a dielectric substrate are due to the reflection of the
field at the air-dielectric slab interface and are proportional to this
reflection coefficient.


title:
Definition and evolution of quantum cellular automata with two qubits
  per cell

abstract:
  Studies of quantum computer implementations suggest cellular quantum computer
architectures. These architectures can simulate the evolution of quantum
cellular automata, which can possibly simulate both quantum and classical
physical systems and processes. It is however known that except for the trivial
case, unitary evolution of one-dimensional homogeneous quantum cellular
automata with one qubit per cell is not possible. Quantum cellular automata
that comprise two qubits per cell are defined and their evolution is studied
using a quantum computer simulator. The evolution is unitary and its linearity
manifests itself as a periodic structure in the probability distribution
patterns.


title:
Electroweak Chiral Lagrangian from Natural Topcolor-assisted Technicolor
  Model

abstract:
  Based on previous studies computing coefficients of the electroweak chiral
Lagrangian from C.T.Hill's schematic topcolor-assisted technicolor model, we
generalize the calculation to K.Lane's prototype natural topcolor-assisted
technicolor model. We find that typical features of the model are qualitatively
similar as those of Hill's model, but Lane's model prefers smaller technicolor
group and Z' mass must be smaller than 400GeV, further S parameter is around
order of +1 mainly due to existence of three doublets of techniquarks. We
obtain the values for all coefficients of the electroweak chiral Lagrangian up
to order of p^4. Apart from negative large four fermion coupling values, ETC
impacts on the electroweak chiral Lagrangian coefficients are small, since
techniquark self energy which determines these coefficients in general receives
almost no influence from ETC induced four fermion interactions except for its
large momentum tail.


title: The Liquid Argon Jet Trigger of the H1 Experiment at HERA

abstract:
  The Liquid Argon Jet Trigger, installed in the H1 experiment at HERA,
implements in 800 ns a real-time cluster algorithm by finding local energy
maxima, summing their immediate neighbors, sorting the resulting "jets" by
energy, and applying topological conditions. It operated since the year 2006
and drastically reduced the thresholds for triggering on electrons and jets.


title: Precise measurement of hadronic tau-decays with an eta meson

abstract:
  We have studied hadronic tau decay modes involving an eta meson using 490
fb^{-1} of data collected with the Belle detector at the KEKB asymmetric-energy
e+e- collider. The following branching fractions have been measured: B(tau- ->
K- eta nu)=(1.58 +- 0.05 +- 0.09)x 10^{-4}, B(tau- -> K- pi0 eta nu)=(4.6 +-
1.1 +- 0.4)x 10^{-5}, B(tau- -> pi- pi0 eta nu)=(1.35 +- 0.03 +- 0.07)x
10^{-3}, B(tau- -> pi- KS eta nu)=(4.4 +- 0.7 +- 0.2)x 10^{-5}, and B(tau- ->
K^{*-} eta nu)=(1.34 +- 0.12 +- 0.09)x 10^{-4}. These results are substantially
more precise than previous measurements. The new measurements are compared with
theoretical calculations based on the CVC hypothesis or the chiral perturbation
theory. We also set upper limits on branching fractions for tau decays into K-
KS eta nu, pi- KS pi0 eta nu, K- eta eta nu, pi- eta eta nu and non-resonant K-
pi^0 eta nu final states.


title:
On central extensions and definably compact groups in o-minimal
  structures

abstract:
  We prove several structural results on definably compact groups G in
o-minimal expansions of real closed fields, such as (i) G is definably an
almost direct product of a semisimple group and a commutative group, and (ii)
the group (G, .) is elementarily equivalent to (G/G^00, .). We also prove
results on the internality of finite covers of G in an o-minimal environment,
as well as the full compact domination conjecture. These results depend on key
theorems about the interpretability of central and finite extensions of
definable groups, in the o-minimal context. These methods and others also yield
interpretability results for universal covers of arbitrary definable real Lie
groups, from which we can deduce the semialgebraicity of finite covers of Lie
groups such as SL(2,R).


title: Switching rates of multi-step reactions

abstract:
  We consider a switching rate of a meta-stable reaction scheme, which includes
reactions with arbitrary steps, e.g. $kA\to(k+r)A$. Employing WKB
approximation, controlled by a large system size, we evaluate both the exponent
and the pre-exponential factor for the rate. The results are illustrated on a
number of examples.


title:
Product formula for Atiyah-Patodi-Singer index classes and higher
  signatures

abstract:
  We define generalized Atiyah-Patodi-Singer boundary conditions of product
type for Dirac operators associated to C*-vector bundles on the product of a
compact manifold with boundary and a closed manifold. We prove a product
formula for the K-theoretic index classes, which we use to generalize the
product formula for the topological signature to higher signatures.