title: Superfluid Response and the Neutrino Emissivity of Neutron Matter

abstract:
  {We calculate the neutrino emissivity of superfluid neutron matter in the
inner crust of neutron stars. We find that neutrino emission due to
fluctuations resulting from the formation of Cooper pairs at finite temperature
is highly suppressed in non-relativistic systems. This suppression of the pair
breaking emissivity in a simplified model of neutron matter with interactions
that conserve spin is of the order of $v_F^4$ for density fluctuations and
$v_F^2$ for spin fluctuations, where $v_F$ is the Fermi velocity of neutrons.
The larger suppression of density fluctuations arises because the dipole moment
of the density distribution of a single component system does not vary in time.
For this reason, we find that the axial current response (spin fluctuations)
dominates. In more realistic models of neutron matter which include tensor
interactions where the neutron spin is not conserved, neutrino radiation from
bremsstrahlung reactions occurs at order $v_F^0$. Consequently, even with the
suppression factors due to superfluidity, this rate dominates near $T_C$.
Present calculations of the pair-breaking emissivity are incomplete because
they neglect the tensor component of the nucleon-nucleon interaction.


title:
Accurate evolutions of inspiralling neutron-star binaries: prompt and
  delayed collapse to black hole

abstract:
  Binary neutron-star (BNS) systems represent primary sources for the
gravitational-wave (GW) detectors. We present a systematic investigation in
full GR of the dynamics and GW emission from BNS which inspiral and merge,
producing a black hole (BH) surrounded by a torus. Our results represent the
state of the art from several points of view: (i) We use HRSC methods for the
hydrodynamics equations and high-order finite-differencing techniques for the
Einstein equations; (ii) We employ AMR techniques with "moving boxes"; (iii) We
use as initial data BNSs in irrotational quasi-circular orbits; (iv) We exploit
the isolated-horizon formalism to measure the properties of the BHs produced in
the merger; (v) Finally, we use two approaches, based either on gauge-invariant
perturbations or on Weyl scalars, to calculate the GWs. These techniques allow
us to perform accurate evolutions on timescales never reported before (ie ~30
ms) and to provide the first complete description of the inspiral and merger of
a BNS leading to the prompt or delayed formation of a BH and to its ringdown.
We consider either a polytropic or an ideal fluid EOS and show that already
with this idealized EOSs a very interesting phenomenology emerges. In
particular, we show that while high-mass binaries lead to the prompt formation
of a rapidly rotating BH surrounded by a dense torus, lower-mass binaries give
rise to a differentially rotating NS, which undergoes large oscillations and
emits large amounts of GWs. Eventually, also the NS collapses to a rotating BH
surrounded by a torus. Finally, we also show that the use of a non-isentropic
EOS leads to significantly different evolutions, giving rise to a delayed
collapse also with high-mass binaries, as well as to a more intense emission of
GWs and to a geometrically thicker torus.


title: Reducing democratic type II supergravity on SU(3) x SU(3) structures

abstract:
  Type II supergravity on backgrounds admitting SU(3) x SU(3) structure and
general fluxes is considered. Using the generalized geometry formalism, we
study dimensional reductions leading to N=2 gauged supergravity in four
dimensions, possibly with tensor multiplets. In particular, a geometric formula
for the full N=2 scalar potential is given. Then we implement a truncation
ansatz, and derive the complete N=2 bosonic action. While the NSNS contribution
is obtained via a direct dimensional reduction, the contribution of the RR
sector is computed starting from the democratic formulation and demanding
consistency with the reduced equations of motion.


title: Prop profile of bi-Hamiltonian structures

abstract:
  Recently S.A. Merkulov established a link between differential geometry and
homological algebra by giving descriptions of several differential geometric
structures in terms of minimal resolutions of props. In particular he described
the prop profile of Poisson geometry. In this paper we define a prop such that
representations of its minimal resolution in a vector space V are in a
one-to-one correspondence with bi-Hamiltonian structures, i.e. pairs of
compatible Poisson structures, on the formal manifold associated to V.


title: About the embedding of Moufang loops in alternative algebras

abstract:
  It is proved that any free Moufang loop can be embedded in a loop of
invertible elements of some alternative algebra.


title:
The Unusual Distributions of Ionized Material and Molecular Hydrogen in
  NGC 6881: Signposts of Multiple Events of Bipolar Ejection in a Planetary
  Nebula

abstract:
  The planetary nebula NGC 6881 displays in the optical a quadrupolar
morphology consisting of two pairs of highly collimated bipolar lobes aligned
along different directions. An additional bipolar ejection is revealed by the
hydrogen molecular emission, but its wide hourglass morphology is very
different from that of the ionized material. To investigate in detail the
spatial distribution of molecular hydrogen and ionized material within NGC
6881, and to determine the prevalent excitation mechanism of the H2 emission,
we have obtained new near-IR Br-gamma and H2 and optical H-alpha and [N II]
images, as well as intermediate resolution JHK spectra. These observations
confirm the association of the H2 bipolar lobes to NGC 6881 and find that the
prevalent excitation mechanism is collisional. The detailed morphology and very
different collimation degree of the H2 and ionized bipolar lobes of NGC 6881
not only imply that multiple bipolar ejections have occurred in this nebula,
but also that the dominant shaping agent is different for each bipolar
ejection: a bipolar stellar wind most likely produced the H2 lobes, while
highly collimated outflows are carving out the ionized lobes into the thick
circumstellar envelope. The asymmetry between the southeast and northwest H2
bipolar lobes suggests the interaction of the nebula with an inhomogeneous
interstellar medium. We find evidence that places NGC 6881 in the H II region
Sh 2-109 along the Orion local spiral arm.


title: Symmetry Breaking for Maximum Satisfiability

abstract:
  Symmetries are intrinsic to many combinatorial problems including Boolean
Satisfiability (SAT) and Constraint Programming (CP). In SAT, the
identification of symmetry breaking predicates (SBPs) is a well-known, often
effective, technique for solving hard problems. The identification of SBPs in
SAT has been the subject of significant improvements in recent years, resulting
in more compact SBPs and more effective algorithms. The identification of SBPs
has also been applied to pseudo-Boolean (PB) constraints, showing that symmetry
breaking can also be an effective technique for PB constraints. This paper
extends further the application of SBPs, and shows that SBPs can be identified
and used in Maximum Satisfiability (MaxSAT), as well as in its most well-known
variants, including partial MaxSAT, weighted MaxSAT and weighted partial
MaxSAT. As with SAT and PB, symmetry breaking predicates for MaxSAT and
variants are shown to be effective for a representative number of problem
domains, allowing solving problem instances that current state of the art
MaxSAT solvers could not otherwise solve.


title: Special cycles on unitary Shimura varieties I. unramified local theory

abstract:
  The supersingular locus in the fiber at p of a Shimura variety attached to a
unitary similitude group GU(1,n-1) over Q is uniformized by a formal scheme
\Cal N. In the case when p is inert, we define special cycles Z(x) in \Cal N,
associated to a collection x of m `special homomorphisms' with fundamental
matrix T in Herm_m(OK). When m=n and T is nonsingular, we show that the cycle
Z(x) is a union of components of the Ekedahl-Oort stratification, and we give a
necessary and sufficient conditions, in terms of T, for Z(x) to be irreducible.
When Z(x) is zero dimensional -- in which case it reduces to a single point --
we determine the length of the corresponding local ring by using a variant of
the theory of quasi-canonical liftings. We show that this length coincides with
the derivative of a representation density for hermitian forms.


title: The fixed point property via dual space properties

abstract:
  A Banach space has the weak fixed point property if its dual space has a
weak$^*$ sequentially compact unit ball and the dual space satisfies the
weak$^*$ uniform Kadec-Klee property; and it has the \fpp if there exists
$\epsilon>0$ such that, for every infinite subset $A$ of the unit sphere of the
dual space, $A\cup (-A)$ fails to be $(2-\epsilon)$-separated. In particular,
$E$-convex Banach spaces, a class of spaces that includes the uniformly
nonsquare spaces, have the fixed point property.


title: Orbital-free effective embedding potential at nuclear cusp

abstract:
  A new approach to approximate the kinetic-energy-functional dependent
component ($v_t[\rho_A,\rho_B](\vec{r})$) of the effective potential in
one-electron equations for orbitals embedded in a frozen density environment
(Eqs. 20-21 in [Wesolowski and Warshel, {\it J. Phys. Chem.} {\bf 97}, (1993)
8050]) is proposed. The exact limit for $v_t$ at $\rho_A\longrightarrow 0$ and
$\int \rho_B d\vec{r}=2$ is enforced. The significance of this limit is
analysed formally and numerically for model systems including a numerically
solvable model and real cases where $\int \rho_B d\vec{r}=2$. A simple
approximation to $v_t[\rho_A,\rho_B](\vec{r})$ is constructed which enforces
the considered limit near nuclei in the environment. Numerical examples are
provided to illustrate the numerical significance of the considered limit for
real systems - intermolecular complexes comprising, non-polar, polar, charged
constituents. Imposing the limit improves significantly the quality of the
approximation to $v_t[\rho_A,\rho_B](\vec{r})$ for systems comprising charged
components. For complexes comprising neutral molecules or atoms the improvement
occurs as well but it is numerically insignificant.


title:
Ground state cooling of a nanomechanical resonator via a Cooper pair box
  qubit

abstract:
  In this paper we present a scheme for ground state cooling of a flexural mode
of a nanomechanical beam incorporated in a loop-shaped Cooper-pair box (CPB)
circuit. Via the Lorentz force coupling of the beam motion to circulating
CPB-circuit currents, energy is transferred to the CPB qubit which acts as a
dissipative two-level system. The cooling process is driven by a detuned
gate-voltage drive acting on the CPB. We analyze the cooling force spectrum and
present analytical expressions for the cooling rate and final occupation number
for a wide parameter regime. In particular, we find that cooling is optimized
in a strong drive regime, and we present the necessary conditions for
ground-state cooling.


title: Adiabatic approximation for many body systems and quantum computation

abstract: This paper has been withdrawn as it has been superseded by 0808.2697


title:
Riemann surfaces with boundary and natural triangulations of the
  Teichmueller space

abstract:
  We compare some natural triangulations of the Teichm\"uller space of
hyperbolic surfaces with geodesic boundary and of some bordifications. We adapt
Scannell-Wolf's proof to show that grafting semi-infinite cylinders at the ends
of hyperbolic surfaces with fixed boundary lengths is a homeomorphism. This
way, we construct a family of triangulations of the Teichm\"uller space of
punctures surfaces that interpolates between Penner-Bowditch-Epstein's (using
the spine construction) and Harer-Mumford-Thurston's (using Strebel's
differentials). Finally, we show (adapting arguments of Dumas) that on a fixed
punctured surface, when the triangulation approaches HMT's, the associated
Strebel differential is well-approximated by the Schwarzian of the associated
projective structure and by the Hopf differential of the collapsing map.


title: Use of the median in Physics and Astronomy

abstract:
  The sample median is often used in statistical analyses of physical or
astronomical data wherein a central value must be found from samples polluted
by elements which do not belong to the population of interest or when the
underlying probability law is such that the sample mean is useless for the
stated purpose. Although it does not generally possesses the nice linearity
properties of the mean, the median has advantages of its own, some of which are
explored in this paper which elucidates analogies and differences between these
two central value descriptors. Some elementary results are shown, most of which
are certainly not new but not widely known either. It is observed that the
moment and the quantile approaches to the description of a probability
distribution are difficult to relate, but that when the quantile description is
used, the sample median can be characterized very much in the same way as the
sample mean; this opens the possibility of using it for estimation purposes
beyond what is usually done. In order to relate the two approaches, a
derivation is given of the asymptotic joint distribution of the mean and the
median for a general continuous probability law.


title: Chains with Fractal Dispersion Law

abstract:
  Chains with long-range interactions are considered. The interactions are
defined such that each nth particle interacts only with chain particles with
the numbers n+a(m) and n-a(m), where m=1,2,3,... and a(m) is an integer-valued
function. Exponential type functions a(m)=b^m, where b=2,3,.., are discussed.
The correspondent pseudodifferential equations of chain oscillations are
obtained. Dispersion laws of the suggested chains are described by the
Weierstrass and Weierstrass-Mandelbrot functions.


title: Noncommutative aspects of open/closed strings via foliations

abstract:
  We give a brief summary of algebraic aspects of string theory arising in the
noncommutative geometry setting of foliations called string diagrammatics which
we introduced jointly with Bob Penner. We furthermore discuss how this gives
rise to actions on the Hochschild complex of a Frobenius algebra. We then
explain how this leads to new quantum chains for loop spaces and a
stabilization in the semi--simple case.


title: Some addition to the generalized Riemann-Hilbert problem

abstract:
  We give some additions to the article "On the generalized Riemann-Hilbert
problem with irregular singularities" by Bolibruch, Malek, Mitschi
(math/0410483). In particular, a weak GRH-problem and the GRH-problem for
scalar differential equations are discussed.


title: Local similarities and the Haagerup property

abstract:
  A new class of groups, the locally finitely determined groups of local
similarities on compact ultrametric spaces, is introduced and it is proved that
groups in this class have the Haagerup property (that is, they are a-T-menable
in the sense of Gromov). The class includes Thompson's groups, which have
already been shown to have the Haagerup property by D. S. Farley, as well as
many other groups acting on boundaries of trees. A sufficient condition, used
in this paper, for the Haagerup property is shown in the appendix by D. S.
Farley to be equivalent to the well-known property of having a proper action on
a space with walls.


title: Channel State Feedback Schemes for Multiuser MIMO-OFDM Downlink

abstract:
  Channel state feedback schemes for the MIMO broadcast downlink have been
widely studied in the frequency-flat case. This work focuses on the more
relevant frequency selective case, where some important new aspects emerge. We
consider a MIMO-OFDM broadcast channel and compare achievable ergodic rates
under three channel state feedback schemes: analog feedback, direction
quantized feedback and "time-domain" channel quantized feedback. The first two
schemes are direct extensions of previously proposed schemes. The third scheme
is novel, and it is directly inspired by rate-distortion theory of Gaussian
correlated sources. For each scheme we derive the conditions under which the
system achieves full multiplexing gain. The key difference with respect to the
widely treated frequency-flat case is that in MIMO-OFDM the frequency-domain
channel transfer function is a Gaussian correlated source. The new time-domain
quantization scheme takes advantage of the channel frequency correlation
structure and outperforms the other schemes. Furthermore, it is by far simpler
to implement than complicated spherical vector quantization. In particular, we
observe that no structured codebook design and vector quantization is actually
needed for efficient channel state information feedback.


title:
Microcanonical quasi-stationarity of long-range interacting systems in
  contact with a heat bath

abstract:
  On the basis of analytical results and molecular dynamics simulations we
clarify the nonequilibrium dynamics of a long-range interacting system in
contact with a heat bath. For small couplings with the bath, we show that the
system can first be trapped in a Vlasov quasi-stationary state, then a
microcanonical one follows, and finally canonical equilibrium is reached at the
bath temperature. We compare a Langevin mesoscopic thermostat with Hamiltonian
reservoirs microscopically coupled with the system and demonstrate the
equivalence of the two descriptions. Our identification of the parameters
determining the quasi-stationary lifetimes could be exploited to control
experimental systems such as the Free Electron Laser, in the presence of
external noise or inherent imperfections.


title: Type IIB Flux Vacua from the String Worldsheet

abstract:
  We study type IIB string compactifications in the presence of RR and NSNS
fluxes using worldsheet techniques. Vertex operators corresponding to internal
RR and NSNS fluxes are constructed in the hybrid formalism with manifest target
space supersymmetry. In a simple class of examples, we compute various known
physical phenomena such as warping and the generation of a superpotential for
complex structure moduli. The results are in precise agreement with the
supergravity literature.


title:
Type IIA AdS4 compactifications on cosets, interpolations and domain
  walls

abstract:
  We present a classification of a large class of type IIA N=1 supersymmetric
compactifications to AdS4, based on left-invariant SU(3)-structures on coset
spaces. In the absence of sources the parameter spaces of all cosets leading to
a solution contain regions corresponding to nearly-Kaehler structure. I.e. all
these cosets can be viewed as deformations of nearly-Kaehler manifolds.
Allowing for (smeared) six-brane/orientifold sources we obtain more
possibilities. In the second part of the paper, we use a simple ansatz, which
can be applied to all six-dimensional coset manifolds considered here, to
construct explicit thick domain wall solutions separating two AdS4 vacua of
different radii. We also consider smooth interpolations between AdS4 x M6 and
R^{1,2} x M7, where M6 is a nearly-Kaehler manifold and M7 is the G2-holonomy
cone over M6.


title:
FIREWORKS U38-to-24 micron photometry of the GOODS-CDFS:
  multi-wavelength catalog and total IR properties of distant Ks-selected
  galaxies

abstract:
  We present a Ks-selected catalog, dubbed FIREWORKS, for the Chandra Deep
Field South (CDFS) containing photometry in U_38, B_435, B, V, V_606, R, i_775,
I, z_850, J, H, Ks, [3.6 um], [4.5 um], [5.8 um], [8.0 um], and the MIPS [24
um] band. The imaging has a typical Ks limit of 24.3 mag (5 sigma, AB) and
coverage over 113 arcmin^2 in all bands and 138 arcmin^2 in all bands but H. We
cross-correlate our catalog with the 1 Ms X-ray catalog by Giacconi et al.
(2002) and with all available spectroscopic redshifts to date. We find and
explain systematic differences in a comparison with the 'z_850 + Ks'-selected
GOODS-MUSIC catalog that covers ~90% of the field. We exploit the U38-to-24
micron photometry to determine which Ks-selected galaxies at 1.5<z<2.5 have the
brightest total IR luminosities and which galaxies contribute most to the
integrated total IR emission. The answer to both questions is that red galaxies
are dominating in the IR. This is true no matter whether color is defined in
the rest-frame UV, optical, or optical-to-NIR. We do find however that among
the reddest galaxies in the rest-frame optical, there is a population of
sources with only little mid-IR emission, suggesting a quiescent nature.


title: Dark spinor inflation -- theory primer and dynamics

abstract:
  Inflation driven by a single dark spinor field is discussed. We define the
notion of a dark spinor field and derive the cosmological field equations for
such a matter source. The conditions for inflation are determined and an
exactly solvable model is presented. We find the power spectrum of the quantum
fluctuation of this field and compare the results with scalar field inflation.


title: Excitons in the One-Dimensional Hubbard Model: a Real-Time Study

abstract:
  We study the real-time dynamics of a pair hole/doubly-occupied-site, namely a
holon and a doublon, in a 1D Hubbard insulator with on-site and
nearest-neighbor Coulomb repulsion. Our analysis shows that the pair is
long-lived and the expected decay mechanism to underlying spin excitations is
actually inefficient. For a nonzero inter-site Coulomb repulsion, we observe
that part of the wave-function remains in a bound state. Our study also
provides insight on the holon-doublon propagation in real space. Due to the
one-dimensional nature of the problem, these particles move in opposite
directions even in the absence of an applied electric field. The potential
relevance of our results to solar cell applications is discussed.


title: Probing doubly charged Higgs in $e^+ e^-$ Colliders in 3-3-1 Model

abstract:
  The SU(3)$_L\otimesU(1)_N$ electroweak model predicts new Higgs bosons beyond
the one of the standard model. In this work we investigate the signature and
production of doubly charged Higgs bosons in the $e^-e^+$ International Linear
Collider and in the CERN Linear Collider. We compute the branching ratios for
the doubly charged gauge bosons of the model.


title:
A model for delayed emission in a very-high energy gamma-ray flare in
  Markarian 501

abstract:
  Recently, the MAGIC collaboration reported evidence for a delay in the
arrival times of photons of different energies during a gamma-ray flare from
the blazar Markarian 501 on 2005 July 9. We apply a homogeneous synchrotron
self-Compton (SSC) model under the assumption that the blob containing
relativistic electrons was observed in its acceleration phase. This modified
SSC model predicts the appearance of a gamma-ray flare first at lower energies
and subsequently at higher energies. Based on the reported time delay of
approx. 240 s between the flare observed at 190 GeV and 2.7 TeV, we predict a
delay on the order of 1 h if observed between 10 GeV and 100 GeV. Such delay
timescales can be tested in the future by simultaneous flare observations with
the Gamma Ray Large Area Space Telescope (GLAST) and Cherenkov telescopes.


title:
Late transient acceleration of the universe in string theory on
  $S^{1}/Z_{2}$

abstract:
  Recently, in Gong {\em et al} \cite{GWW07} and Wang and Santos \cite{WS07} it
was shown that the effective cosmological constant on each of the two orbifold
branes can be easily lowered to its current observational value, by using the
large extra dimensions in the framework of both M-Theory and string theory on
$S^{1}/Z_{2}$. In this paper, we study the current acceleration of the
universe, using the formulas developed in \cite{WS07}. We first construct
explicitly time-dependent solution to the 10-dimensional bulk of the
Neveu-Schwarz/Neveu-Schwarz sector, compactified on a 5-dimensional torus.
Then, we write down the generalized Friedmann equations on each of the two
dynamical branes, and fit the models to the 182 gold supernova Ia data and the
BAO parameter from SDSS, using both of our MINUIT and Monte-Carlo Markov Chain
(MCMC) codes. With the best fitting values of the parameters involved as
initial conditions, we integrate the generalized Friedmann equations
numerically and find the future evolution of the universe. We find that it
depends on the choice of the radion potentials $V_{4}^{(I)} (I = 1, 2)$ of the
branes. In particular, when choosing them to be the Goldberger-Wise potentials,
$V_{4}^{(I)} = \lambda_{4}^{(I)} (\psi^{2} - {v_{I}}^{2})^{2}$, we find that
the current acceleration of the universe driven by the effective cosmological
constant is only temporary. Due to the effects of the potentials, the universe
will be finally in its decelerating expansion phase again. We also study the
proper distance between the two branes, and find that it remains almost
constant during the whole future evolution of the universe in all the models
considered.


title: Is there anything special about GRB 080319B?

abstract:
  We show that the properties of gamma ray burst 080319B and its afterglow are
well reproduced by the cannonball model of long gamma ray bursts (GRBs). It was
an ordinary GRB, produced by a jet of highly relativistic plasmoids (CBs),
ejected in a core-collapse supernova (SN) and viewed, as some others before,
particularly close to the CB-emission axis. It still remains to be seen whether
GRB 080319B was associated with an SN akin to SN1998bw, the SN type ordinarily
associated with GRBs, or with a much more luminous SN.


title:
A Weakly Coupled Ultraviolet Completion of the Littlest Higgs with
  T-parity

abstract:
  We construct a weakly coupled, renormalizable ultraviolet completion of the
Littlest Higgs model with T-parity (LHT), based on an SU(5)xSU(2)xU(1) gauge
theory with a discrete Z_2 symmetry. Our model reproduces the complete
structure of the LHT below the 10 TeV scale, including the collective symmetry
breaking mechanism which solves the little hierarchy problem. The model is
manifestly free of anomalies, including both gauge/gravitational anomalies and
anomalies involving T-parity. At the TeV scale, the model contains additional
states not present in the LHT. We estimate the impact of these states on
precision electroweak observables, and show that the model is realistic. We
also discuss how our model can be embedded into a supersymmetric theory or a
five-dimensional setup with a warped extra dimension, stabilyzing the hierarchy
between the 10 TeV and the Planck scale.


title: K-vacancy levels in Ne, Mg, Si, S, Ar, and Ca

abstract:
  The HFR and AUTOSTRUCTURE atomic structure codes are used to compute complete
data sets of level energies, wavelengths, A-values, and radiative and Auger
widths for K-vacancy states of the Ne, Mg, Si, S, Ar, and Ca isonuclear
sequences. Ions with electron number N>9 are treated for the first time.
Detailed comparisons with previous measurements and theoretical data for ions
with N<=9 are carried out in order to estimate reliable accuracy ratings.


title:
The Number of Pseudo-Anosov Elements in the Mapping Class Group of a
  Four-Holed Sphere

abstract:
  We compute the growth series and the growth functions of reducible and
pseudo-Anosov elements of the pure mapping class group of the sphere with four
holes with respect to a certain generating set. We prove that the ratio of the
number of pseudo-Anosov elements to that of all elements in a ball with center
at the identity tends to one as the radius of the ball tends to infinity.


title: Topological order from quantum loops and nets

abstract:
  I define models of quantum loops and nets which have ground states with
topological order. These make possible excited states comprised of deconfined
anyons with non-abelian braiding. With the appropriate inner product, these
quantum loop models are equivalent to net models whose topological weight
involves the chromatic polynomial. A useful consequence is that the models have
a quantum self-duality, making it possible to find a simple Hamiltonian
preserving the topological order. For the square lattice, this Hamiltonian has
only four-spin interactions.


title: Geometric spaces from arbitrary convex polytopes

abstract:
  We associate a geometric space to an arbitrary convex polytope. Our
construction parallels the construction by D. Cox of a toric variety as a GIT
quotient. The spaces that we obtain are endowed with a natural stratification
and perfectly mimic the features of toric varieties associated to rational
convex polytopes.


title:
A Numerical Model for Brownian Particles Fluctuating in Incompressible
  Fluids

abstract:
  We present a numerical method that consistently implements thermal
fluctuations and hydrodynamic interactions to the motion of Brownian particles
dispersed in incompressible host fluids. In this method, the thermal
fluctuations are introduced as random forces acting on the Brownian particles.
The hydrodynamic interactions are introduced by directly resolving the fluid
motions with the particle motion as a boundary condition to be satisfied. The
validity of the method has been examined carefully by comparing the present
numerical results with the fluctuation-dissipation theorem whose analytical
form is known for dispersions of a single spherical particle. Simulations are
then performed for more complicated systems, such as a dispersion composed of
many spherical particles and a single polymeric chain in a solvent.


title:
Wormholes and trumpets: the Schwarzschild spacetime for the
  moving-puncture generation

abstract:
  We expand upon our previous analysis of numerical moving-puncture simulations
of the Schwarzschild spacetime. We present a derivation of the family of
analytic stationary 1+log foliations of the Schwarzschild solution, and outline
a transformation to isotropic-like coordinates. We discuss in detail the
numerical evolution of standard Schwarzschild puncture data, and the new
time-independent 1+log data. Finally, we demonstrate that the moving-puncture
method can locate the appropriate stationary geometry in a robust manner when a
numerical code alternates between two forms of 1+log slicing during a
simulation.


title:
Short expressions of permutations as products and cryptanalysis of the
  Algebraic Eraser

abstract:
  On March 2004, Anshel, Anshel, Goldfeld, and Lemieux introduced the
\emph{Algebraic Eraser} scheme for key agreement over an insecure channel,
using a novel hybrid of infinite and finite noncommutative groups. They also
introduced the \emph{Colored Burau Key Agreement Protocol (CBKAP)}, a concrete
realization of this scheme.
  We present general, efficient heuristic algorithms, which extract the shared
key out of the public information provided by CBKAP. These algorithms are,
according to heuristic reasoning and according to massive experiments,
successful for all sizes of the security parameters, assuming that the keys are
chosen with standard distributions.
  Our methods come from probabilistic group theory (permutation group actions
and expander graphs). In particular, we provide a simple algorithm for finding
short expressions of permutations in $S_n$, as products of given random
permutations. Heuristically, our algorithm gives expressions of length
$O(n^2\log n)$, in time and space $O(n^3)$. Moreover, this is provable from
\emph{the Minimal Cycle Conjecture}, a simply stated hypothesis concerning the
uniform distribution on $S_n$. Experiments show that the constants in these
estimations are small. This is the first practical algorithm for this problem
for $n\ge 256$.
  Remark: \emph{Algebraic Eraser} is a trademark of SecureRF. The variant of
CBKAP actually implemented by SecureRF uses proprietary distributions, and thus
our results do not imply its vulnerability. See also arXiv:abs/12020598


title: Polarization Saturation in Strained Ferroelectrics

abstract:
  Using density-functional calculations we study the structure and polarization
response of tetragonal PbTiO3, BaTiO3 and SrTiO3 in a strain regime that is
previously overlooked. Different from common expectations, we find that the
polarizations in all three substances saturate at large strains, demonstrating
a universal phenomenon. The saturation is shown to originate from an unusual
and strong electron-ion correlation that leads to cancellation between
electronic and ionic polarizations. Our results shed new insight on the
polarization properties, and reveal the existence of a fundamental limit to the
strain-induced polarization enhancement.


title:
An application of the Casoratian technique to the 2D Toda lattice
  equation

abstract:
  A general Casoratian formulation is proposed for the 2D Toda lattice
equation, which involves coupled eigenfunction systems. Various Casoratian type
solutions are generated, through solving the resulting linear conditions and
using a Baecklund transformation.


title: Reconstructing AdS/CFT

abstract:
  In this note we clarify the dictionary between pure quantum gravity on the
bulk in the presence of a cosmological constant and a CFT on the boundary. We
show for instance that there is a general correspondence between quantum
gravity ``radial states'' and a pair of CFT's. Restricting to one CFT is argued
to correspond to states possessing an asymptotic infinity. This point of view
allows us to address the problem of reconstructing the bulk from the boundary.
And in the second part of this paper we present an explicit formula which
gives, from the partition function of any 2 dimensional conformal field theory,
a wave functional solution to the 3-dimensional Wheeler-DeWitt equation. This
establishes at the quantum level a precise dictionary between 2d CFT and pure
gravity.


title: Non-Commutative Partial Matrix Convexity

abstract:
  Let $p$ be a polynomial in the non-commuting variables
$(a,x)=(a_1,...,a_{g_a},x_1,...,x_{g_x})$. If $p$ is convex in the variables
$x$, then $p$ has degree two in $x$ and moreover, $p$ has the form $p = L +
\Lambda ^T \Lambda,$ where $L$ has degree at most one in $x$ and $\Lambda$ is a
(column) vector which is linear in $x,$ so that $\Lambda^T\Lambda$ is a both
sum of squares and homogeneous of degree two. Of course the converse is true
also. Further results involving various convexity hypotheses on the $x$ and $a$
variables separately are presented.


title: Initial Conditions of Closed Classical Orbits from Quantum Spectra

abstract:
  A method is presented for determining the initial conditions of classical
orbits from the quantum spectra of the diamagnetic hydrogen atom. Each
classical trajectory which is closed at the nucleus produces a sinusoidal
fluctuation in the photoabsorption spectrum. The amplitude of each orbit's
contribution appears in the Fourier transform of a spectrum computed at
constant scaled energy. For a given initial state, closed-orbit theory gives
the dependence of this recurrence amplitude on the initial angle of an orbit.
By comparing the recurrence amplitudes for different initial states, the
initial conditions of closed classical orbits are determined from quantum
spectra.

categories: physics.atom-ph nlin.CD physics.class-ph quant-ph


title: Source Coding with Mismatched Distortion Measures

abstract:
  We consider the problem of lossy source coding with a mismatched distortion
measure. That is, we investigate what distortion guarantees can be made with
respect to distortion measure $\tilde{\rho}$, for a source code designed such
that it achieves distortion less than $D$ with respect to distortion measure
$\rho$. We find a single-letter characterization of this mismatch distortion
and study properties of this quantity. These results give insight into the
robustness of lossy source coding with respect to modeling errors in the
distortion measure. They also provide guidelines on how to choose a good
tractable approximation of an intractable distortion measure.


title: Conformal Gauge Mediation and Light Gravitino of Mass m_{3/2} <O(10) eV

abstract:
  We discuss a class of gauge mediated supersymmetry breaking models with
conformal invariance above the messenger mass scale (conformal gauge
mediation). The spectrum of the supersymmetric particles including the
gravitino is uniquely determined by the messenger mass. When the conformal
fixed point is strongly interacting, it predicts a light gravitino of mass
m_{3/2}<O(10) eV, which is attractive since such a light gravitino causes no
problem in cosmology.


title: A Complete Classification of Ternary Self-Dual Codes of Length 24

abstract:
  Ternary self-dual codes have been classified for lengths up to 20. At length
24, a classification of only extremal self-dual codes is known. In this paper,
we give a complete classification of ternary self-dual codes of length 24 using
the classification of 24-dimensional odd unimodular lattices.


title: Groebner-Shirshov bases for dialgebras

abstract:
  In this paper, we define the Gr\"obner-Shirshov basis for a dialgebra. The
Composition-Diamond lemma for dialgebras is given then. As results, we give
Gr\"obner-Shirshov bases for the universal enveloping algebra of a Leibniz
algebra, the bar extension of a dialgebra, the free product of two dialgebras,
and Clifford dialgebra. We obtain some normal forms for algebras mentioned the
above.


title: Groebner-Shirshov bases for extensions of algebras

abstract:
  An algebra $\cal{R}$ is called an extension of the algebra $M$ by $B$ if
$M^2=0$, $M$ is an ideal of $\cal{R}$ and $\cal{R}$$/M\cong B$ as algebras. In
this paper, by using the Gr\"{o}bner-Shirshov bases, we characterize completely
the extensions of $M$ by $B$. An algorithm to find the conditions of an algebra
$A$ to be an extension of $M$ by $B$ is obtained.


title: Further Hopping with Toads and Frogs

abstract:
  We show the value of positions of the combinatorial game ``Toads and Frogs''.
  We present new values of starting positions. Moreover, we discuss the values
of all positions with exactly one $\Box, \regT^{a}\Box\Box \regF^{a}, \regT^{a}
\Box \Box \Box \regF \regF \regF,\regT^{a}\Box\Box \regF^{b}$,
$\regT^{a}\Box\Box\Box \regF^{b}$. At the end, we post five new conjectures and
discuss the possible future work.


title: Groebner-Shirshov bases for Schreier extensions of groups

abstract:
  In this paper, by using the Groebner-Shirshov bases, we give
characterizations of the Schreier extensions of groups when the group is
presented by generators and relations. An algorithm to find the conditions of a
group to be a Schreier extension is obtained. By introducing a special total
order, we obtain the structure of the Schreier extension by an HNN group.


title:
Groebner-Shirshov basis for HNN extensions of groups and for the
  alternating group

abstract:
  In this paper, we generalize the Shirshov's Composition Lemma by replacing
the monomial order for others. By using Groebner-Shirshov bases, the normal
forms of HNN extension of a group and the alternating group are obtained.


title: Groebner-Shirshov bases for some one-relator groups

abstract:
  In this paper, we prove that two-generator one-relator groups with depth less
than or equal to 3 can be effectively embedded into a tower of HNN-extensions
in which each group has the effective standard normal form. We give an example
to show how to deal with some general cases for one-relator groups. By using
the Magnus method and Composition-Diamond Lemma, we reprove the G. Higman, B.
H. Neumann and H. Neumann's embedding theorem.


title: Star Forming Galaxies at z > 5

abstract:
  We present recent progress in searching for galaxies at redshift from z = 5
to z = 10. Wide-field and senstive surveys with 8m class telescopes have been
providing more than several hundreds of star forming galaxies at z =5 - 7 that
are probed in the optical window. These galaxies are used to study the early
cosmic star formation activity as well as the early structure formation in the
universe. Moreover, near infrared deep imaging and spectropscopic surveys have
found probable candidates of galaxies from z = 7 to z = 10. Although these
candidates are too faint to be identified unambiguously, we human being are now
going to the universe beyond 13 billion light years, close to the epoch of
first-generations stars; i.e., Population III stars. We also mention about
challanges to find Population III-dominated galaxies in the early universe.


title: Finite Trigonometric Character Sums Via Discrete Fourier Analysis

abstract:
  We prove several old and new theorems about finite sums involving characters
and trigonometric functions. These sums can be traced back to theta function
identities from Ramanujan's notebooks and were systematically first studied by
Berndt and Zaharescu; their proofs involved complex contour integration. We
show how to prove most of Berndt-Zaharescu's and some new identities by
elementary methods of discrete Fourier Analysis.


title: Homological mirror symmetry is T-duality for $\mathbb P^n$

abstract:
  In this paper, we apply the idea of T-duality to projective spaces. From a
connection on a line bundle on $\mathbb P^n$, a Lagrangian in the mirror
Landau-Ginzburg model is constructed. Under this correspondence, the full
strong exceptional collection $\mathcal O_{\mathbb P^n}(-n-1),...,\mathcal
O_{\mathbb P^n}(-1)$ is mapped to standard Lagrangians in the sense of
\cite{nz}. Passing to constructible sheaves, we explicitly compute the quiver
structure of these Lagrangians, and find that they match the quiver structure
of this exceptional collection of $\mathbb P^n$. In this way, T-duality
provides quasi-equivalence of the Fukaya category generated by these
Lagrangians and the category of coherent sheaves on $\mathbb P^n$, which is a
kind of homological mirror symmetry.


title: Scalar Mesons in Charm Decays

abstract:
  Results on light scalar mesons in charmed particle decays studied by the CLEO
Collaboration at the Cornell Electron Storage Ring are reviewed.


title:
Rare Decays of \Lambda_b->\Lambda + \gamma and \Lambda_b ->\Lambda +
  l^{+} l^{-} in the Light-cone Sum Rules

abstract:
  Within the Standard Model, we investigate the weak decays of $\Lambda_b \to
\Lambda + \gamma$ and $\Lambda_b \to \Lambda + l^{+} l^{-}$ with the light-cone
sum rules approach. The higher twist distribution amplitudes of $\Lambda$
baryon to the leading conformal spin are included in the sum rules for
transition form factors. Our results indicate that the higher twist
distribution amplitudes almost have no influences on the transition form
factors retaining the heavy quark spin symmetry, while such corrections can
result in significant impacts on the form factors breaking the heavy quark spin
symmetry. Two phenomenological models (COZ and FZOZ) for the wave function of
$\Lambda$ baryon are also employed in the sum rules for a comparison, which can
give rise to the form factors approximately 5 times larger than that in terms
of conformal expansion. Utilizing the form factors calculated in LCSR, we then
perform a careful study on the decay rate, polarization asymmetry and
forward-backward asymmetry, with respect to the decays of $\Lambda_b \to
\Lambda \gamma$, $\Lambda l^{+}l^{-}$.


title: Panel Discussion on Scalar Mesons

abstract:
  A panel discussion on scalar mesons was held with the participation of David
Bugg, Yulia Kalashnikova, Keh-Fei Liu, Michael Scadron, the author, and members
of the audience. Some introductory remarks are noted here.


title:
Storms prediction : Logistic regression vs random forest for unbalanced
  data

abstract:
  The aim of this study is to compare two supervised classification methods on
a crucial meteorological problem. The data consist of satellite measurements of
cloud systems which are to be classified either in convective or non convective
systems. Convective cloud systems correspond to lightning and detecting such
systems is of main importance for thunderstorm monitoring and warning. Because
the problem is highly unbalanced, we consider specific performance criteria and
different strategies. This case study can be used in an advanced course of data
mining in order to illustrate the use of logistic regression and random forest
on a real data set with unbalanced classes.


title: U-duality Invariant Dyon Spectrum in type II on T^6

abstract:
  We give a manifestly U-duality invariant formula for the degeneracy of 1/8
BPS dyons in type II string theory on T^6 for a U-duality invariant subset of
charge vectors. Besides depending on the Cremmer-Julia invariant the degeneracy
also depends on other discrete invariants of E_{7(7)}(Z).


title:
Hawking Radiation, Gravitational Anomaly and Conformal Symmetry - the
  Origin of Universality -

abstract:
  The universal behavior of Hawking radiation is originated in the conformal
symmetries of matter fields near the black hole horizon. We explain the origin
of this universality based on (1) the gravitational anomaly and its higher-spin
generalizations and (2) conformal transformation properties of fluxes.


title:
MOA-cam3: a wide-field mosaic CCD camera for a gravitational
  microlensing survey in New Zealand

abstract:
  We have developed a wide-field mosaic CCD camera, MOA-cam3, mounted at the
prime focus of the Microlensing Observations in Astrophysics (MOA) 1.8-m
telescope. The camera consists of ten E2V CCD4482 chips, each having 2kx4k
pixels, and covers a 2.2 deg^2 field of view with a single exposure. The
optical system is well optimized to realize uniform image quality over this
wide field. The chips are constantly cooled by a cryocooler at -80C, at which
temperature dark current noise is negligible for a typical 1-3 minute exposure.
The CCD output charge is converted to a 16-bit digital signal by the GenIII
system (Astronomical Research Cameras Inc.) and readout is within 25 seconds.
Readout noise of 2--3 ADU (rms) is also negligible. We prepared a wide-band red
filter for an effective microlensing survey and also Bessell V, I filters for
standard astronomical studies. Microlensing studies have entered into a new
era, which requires more statistics, and more rapid alerts to catch exotic
light curves. Our new system is a powerful tool to realize both these
requirements.


title: Little Randall-Sundrum Model and a Multiply Warped Spacetime

abstract:
  A recent work has investigated the possibility that the mass scale for the
ultraviolet (UV) brane in the Randall-Sundrum (RS) model is of the order 10^3
TeV. In this so called ``Little Randall-Sundrum'' (LRS) model the bounds on the
gauge sector are less severe, permitting a lower Kaluza-Klein scale and cleaner
discovery channels. However employing a low UV scale nullifies one major appeal
of the RS model; namely the elegant explanation of the hierarchy between the
Planck and weak scales. In this work we show that by localizing the gauge,
fermion and scalar sector of the LRS model on a five dimensional slice of a
doubly warped spacetime one may obtain the low UV brane scale employed in the
LRS model and motivate the weak-Planck hierarchy. We also consider the
generalization to an n-warped spacetime.


title: Identities between Appell's and hypergeometric functions

abstract:
  Univariate specializations of Appell's hypergeometric functions F1, F2, F3,
F4 satisfy ordinary Fuchsian equations of order at most 4. In special cases,
these differential equations are of order 2, and could be simple (pullback)
transformations of Euler's differential equation for the Gauss hypergeometric
function. The paper classifies these cases, and presents corresponding
relations between univariate specializations of Appell's functions and
univariate hypergeometric functions. The computational aspect and interesting
identities are discussed.


title: The role of $N^{*}(1535)$ in $\eta '$ production

abstract:
  We study the near-threshold $\eta '$ production mechanism in nucleon-nucleon
and $\pi N$ collisions under the assumption that sub-threshold resonance
$N^{*}(1535)$ is predominant. In an effective Lagrangian approach which gives a
reasonable description to the $pN \to pN \eta$ and $\pi p \to p \eta$
reactions, it is found that t-channel $\pi$ exchange make the dominate
contribution to the $pN \to pN \eta '$ process, and a value of 6.5 for the
ratio of $\sigma (pn \to pn \eta ')$ to $\sigma (pp \to pp \eta ')$ is
predicted. A strong coupling strength of $N^{*}(1535)$ to $\eta ' N$ ($g_{\eta
' NN^*}^2 /4\pi = 1.1$) is extracted from a combined analysis to $pp \to pp
\eta '$ and $\pi N \to N \eta '$, and the possible implication to the intrinsic
component of $N^{*}(1535)$ is explored.


title: The discrete square peg problem

abstract:
  The square peg problem asks whether every Jordan curve in the plane has four
points which form a square. The problem has been resolved (positively) for
various classes of curves, but remains open in full generality. We present two
new direct proofs for the case of piecewise linear curves.


title:
Estimating the Number of Components in a Mixture of Multilayer
  Perceptrons

abstract:
  BIC criterion is widely used by the neural-network community for model
selection tasks, although its convergence properties are not always
theoretically established. In this paper we will focus on estimating the number
of components in a mixture of multilayer perceptrons and proving the
convergence of the BIC criterion in this frame. The penalized
marginal-likelihood for mixture models and hidden Markov models introduced by
Keribin (2000) and, respectively, Gassiat (2002) is extended to mixtures of
multilayer perceptrons for which a penalized-likelihood criterion is proposed.
We prove its convergence under some hypothesis which involve essentially the
bracketing entropy of the generalized score-functions class and illustrate it
by some numerical examples.


title: Steganography from weak cryptography

abstract:
  We introduce a problem setting which we call ``the freedom fighters'
problem''. It subtly differs from the prisoners' problem. We propose a
steganographic method that allows Alice and Bob to fool Wendy the warden in
this setting. Their messages are hidden in encryption keys. The recipient has
no prior knowledge of these keys, and has to cryptanalyze ciphertexts in order
to recover them. We show an example of the protocol and give a partial security
analysis.


title:
Weak Affine Light Typing is complete with respect to Safe Recursion on
  Notation

abstract:
  Weak affine light typing (WALT) assigns light affine linear formulae as types
to a subset of lambda-terms of System F. WALT is poly-time sound: if a
lambda-term M has type in WALT, M can be evaluated with a polynomial cost in
the dimension of the derivation that gives it a type. The evaluation proceeds
under any strategy of a rewriting relation which is a mix of both call-by-name
and call-by-value beta-reductions. WALT weakens, namely generalizes, the notion
of "stratification of deductions", common to some Light Systems -- those
logical systems, derived from Linear logic, to characterize the set of
Polynomial functions -- . A weaker stratification allows to define a
compositional embedding of Safe recursion on notation (SRN) into WALT. It turns
out that the expressivity of WALT is strictly stronger than the one of the
known Light Systems. The embedding passes through the representation of a
subsystem of SRN. It is obtained by restricting the composition scheme of SRN
to one that can only use its safe variables linearly. On one side, this
suggests that SRN, in fact, can be redefined in terms of more primitive
constructs. On the other, the embedding of SRN into WALT enjoys the two
following remarkable aspects. Every datatype, required by the embedding, is
represented from scratch, showing the strong structural proof-theoretical roots
of WALT. Moreover, the embedding highlights a stratification structure of the
normal and safe arguments, normally hidden inside the world of SRN-normal/safe
variables: the less an argument is "polyomially impredicative", the deeper, in
a formal, proof-theoretical sense, it is represented inside WALT. Finally,
since WALT is SRN-complete it is also polynomial-time complete since SRN is.


title:
Astrophysical Implications of Equation of State for Hadron-Quark Mixed
  Phase: Compact Stars and Stellar Collapses

abstract:
  We construct an equation of state including the hadron-quark phase
transition. The mixed phase is obtained by the Gibbs conditions for finite
temperature. We adopt the equation of state based on the relativistic mean
field theory for the hadronic phase taking into account pions. As for the quark
phase, the MIT bag model of the deconfined 3-flavor strange quark matter is
used. As a result, our equation of state is thermodynamically stable and
exhibits qualitatively the desired properties of hadron-quark mixed matter,
such as the temperature dependence of the transition density. The pions raise
the transition density because they make the equation of state softer. Using
the equation of state constructed here, we study its astrophysical
implications. The maximum mass of compact stars is investigated, and our
equation of state is consistent with recent observations. We also compute the
collapse of a massive star with 100 solar masses using our equation of state
and find that the interval time from the bounce to the black hole formation
becomes shorter for the model with pions and quarks. The pions and quarks
affect the total energy of the emitted neutrinos because the duration time of
the neutrino emission becomes shorter. The neutrino luminosity rises under the
effect of pions since the density of the proto-neutron star becomes high.


title:
To the construction of symmetry-dependent inhomogeneity Landau theory of
  state and its relationship to field theory

abstract:
  The paper shows that inhomogeneity of translation properties of condensate
leads to the interaction of local order parameter (OP) and its compensating
field which is similar to gauge fields in the field theory. Dynamic models were
considered in the theory of phase transitions to inhomogeneous state with local
translational symmetry, generalizing analogous models of static description
[A.Ya Braginsky, Phys. Rev. B66, 054202 (2002); A.Ya. Braginsky, Zh. Eksp.
Teor. Fiz. 132, 30 (2007)], where internal stress inevitably arises. In dynamic
models, symmetry-dependent stress tensor defines force, and continuous group
parameters of the local Landau potential are linked with the laws of
conservation and equations of continuity. Equations of continuity for momentum
in the present model are in agreement with the second Newton's law and result
from the equations of state, by analogy with equations of continuity for
current, obtained from Maxwell equations in electrodynamics. It is shown that
the principle of local homogeneity corresponds to the model of continuum with
fibering of space into locally homogeneous subspaces in each of its points,
resulting in the gauge model with minimal interaction in the Landau theory.
Phenomenological charge responsible for minimal interaction of an order
parameter (OP) and its compensating field linearly enters the expression for
momentum, that being in agreement with the principle of equivalence of masses.
Local Landau theory is consistent with ideas of quantum mechanics, because
condensate, in a small volume, has wave properties and describes the wave
function, which is transformed to local irreducible representation (IR) of the
subgroup of translations.


title:
Cavity-enhanced radiative emission rate in a single-photon-emitting
  diode operating at 0.5 GHz

abstract:
  We report the observation of a Purcell enhancement in the electroluminescence
decay rate of a single quantum dot, embedded in a microcavity
light-emitting-diode structure. Lateral confinement of the optical mode was
achieved using an annulus of low-refractive-index aluminium oxide, formed by
wet oxidation. The same layer acts as a current aperture, reducing the active
area of the device without impeding the electrical properties of the p-i-n
diode. This allowed single photon electroluminescence to be demonstrated at
repetition rates up to 0.5 GHz.


title:
Wide-Field Infrared Imaging Polarimetry of the NGC 6334 Region: A Nest
  of Infrared Reflection Nebulae

abstract:
  We report the detection of eighteen infrared reflection nebulae (IRNe) in the
$J$, $H$, & $Ks$ linear polarimetric observations of the NGC 6334 massive
star-formation complex, of which 16 IRNe are new discoveries. Our images cover
$\sim$180 square arcminutes, one of the widest near-infrared polarization data
in star-formation regions so far. These IRNe are most likely associated with
embedded young OB stars at different evolutionary phases, showing a variety of
sizes, morphologies, and polarization properties, which can be divided into
four categories. We argue the different nebula characteristics to be a possible
evolutionary sequence of circumstellar structures around young massive stars.


title:
Comment on ``Self-organized criticality and absorbing states: Lessons
  from the Ising model"

abstract:
  According to Pruessner and Peters [Phys. Rev. E {\bf 73}, 025106(R) (2006)],
the finite size scaling exponents of the order parameter in sandpile models
depend on the tuning of driving and dissipation rates with system size. We
point out that the same is not true for {\em avalanches} in the slow driving
limit.


title: On a secondary invariant of the hyperelliptic mapping class group

abstract:
  In this paper, we discuss relations among several invariants of 3-manifolds
including Meyer's function, the eta-invariant, the von Neumann rho-invariant
and the Casson invariant from the viewpoint of the mapping class group of a
surface.


title:
Computation of the temperature dependence of the heat capacity of
  complex molecular systems using random color noise

abstract:
  We propose a new method for computing the temperature dependence of the heat
capacity in complex molecular systems. The proposed scheme is based on the use
of the Langevin equation with low frequency color noise. We obtain the
temperature dependence of the correlation time of random noises, which enables
to model the partial thermalization of high-frequency vibrations, which is a
pure quantum effect. By applying the method to carbon nanotubes, we show that
the consideration of the color noise in the Langevin equation allows to
reproduce the temperature evolution of the specific heat with good accuracy.


title: Small Resolutions and Non-Liftable Calabi-Yau threefolds

abstract:
  We use properties of small resolutions of the ordinary double point in
dimension three to construct smooth non-liftable Calabi-Yau threefolds. In
particular, we construct a smooth projective Calabi-Yau threefold over $\F_3$
that does not lift to characteristic zero and a smooth projective Calabi-Yau
threefold over $\F_5$ having an obstructed deformation. We also construct many
examples of smooth Calabi-Yau algebraic spaces over $\F_p$ that do not lift to
algebraic spaces in characteristic zero.


title: Quantum Dynamics of Multiferroic Helimagnets: a Schwinger-Boson Approach

abstract:
  We study the quantum dynamics/fluctuation of the cycloidal helical magnet in
terms of the Schwinger boson approach. In sharp contrast to the classical
fluctuation, the quantum fluctuation is collinear in nature which gives rise to
the collinear spin density wave state slightly above the helical cycloidal
state as the temperature is lowered. Physical properties such as the reduced
elliptic ratio of the spiral, the neutron scattering and infrared absorption
spectra are discussed from this viewpoint with the possible relevance to the
quasi-one dimensional LiCu$_2$O$_2$ and LiCuVO$_4$.


title:
Diffuse neutron reflectivity and AFM study of interface morphology of an
  electro-deposited Ni/Cu film

abstract:
  We present a detailed study of the interface morphology of an
electro-deposited (ED) Ni/Cu bilayer film by using off-specular (diffuse)
neutron reflectivity technique and Atomic Force Microscopy (AFM). The Ni/Cu
bilayer has been electro-deposited on seed layers of Ti/Cu. These two seed
layers were deposited by magnetron sputtering. The depth profile of density in
the sample has been obtained from specular neutron reflectivity data. AFM image
of the air-film interface shows that the surface is covered by globular islands
of different sizes. The AFM height distribution of the surface clearly shows
two peaks [Fig. 3] and the relief structure (islands) on the surface in the
film can be treated as a quasi-two-level random rough surface structure. We
have demonstrated that the detailed morphology of air-film interfaces, the
quasi-two level surface structure as well as morphology of the buried
interfaces can be obtained from off-specular neutron reflectivity data. We have
shown from AFM and off-specular neutron reflectivity data that the morphologies
of electro-deposited surface is distinctly different from that of
sputter-deposited interface in this sample. To the best of our knowledge this
is the first attempt to microscopically quantify the differences in
morphologies of metallic interfaces deposited by two different techniques viz.
electro-deposition and sputtering.


title:
A theoretical comparison of the data augmentation, marginal augmentation
  and PX-DA algorithms

abstract:
  The data augmentation (DA) algorithm is a widely used Markov chain Monte
Carlo (MCMC) algorithm that is based on a Markov transition density of the form
$p(x|x')=\int_{\mathsf{Y}}f_{X|Y}(x|y)f_{Y|X}(y|x') dy$, where $f_{X|Y}$ and
$f_{Y|X}$ are conditional densities. The PX-DA and marginal augmentation
algorithms of Liu and Wu [J. Amer. Statist. Assoc. 94 (1999) 1264--1274] and
Meng and van Dyk [Biometrika 86 (1999) 301--320] are alternatives to DA that
often converge much faster and are only slightly more computationally
demanding. The transition densities of these alternative algorithms can be
written in the form $p_R(x|x')=\int_{\mathsf{Y}}\int
_{\mathsf{Y}}f_{X|Y}(x|y')R(y,dy')f_{Y|X}(y|x') dy$, where $R$ is a Markov
transition function on $\mathsf{Y}$. We prove that when $R$ satisfies certain
conditions, the MCMC algorithm driven by $p_R$ is at least as good as that
driven by $p$ in terms of performance in the central limit theorem and in the
operator norm sense. These results are brought to bear on a theoretical
comparison of the DA, PX-DA and marginal augmentation algorithms. Our focus is
on situations where the group structure exploited by Liu and Wu is available.
We show that the PX-DA algorithm based on Haar measure is at least as good as
any PX-DA algorithm constructed using a proper prior on the group.


title: Quantum Cosmology

abstract:
  We give an introduction into quantum cosmology with emphasis on its
conceptual parts. After a general motivation we review the formalism of
canonical quantum gravity on which discussions of quantum cosmology are usually
based. We then present the minisuperspace Wheeler--DeWitt equation and
elaborate on the problem of time, the imposition of boundary conditions, the
semiclassical approximation, the origin of irreversibility, and singularity
avoidance. Restriction is made to quantum geometrodynamics; loop quantum
gravity and string theory are discussed in other contributions to this volume.


title: Generalizing Hartogs' Trichotomy Theorem

abstract:
  A celebrated argument of F. Hartogs (1915) deduces the Axiom of Choice from
the hypothesis of comparability for any pair of cardinals. We show how each of
a sequence of seemingly much weaker hypotheses suffices. Fixing a finite number
$k>1$, the Axiom of Choice follows if merely any family of $k$ cardinals
contains at least one comparable pair.


title: Differential invariants of 2--order ODEs, I

abstract:
  In this paper, we investigate the action of pseudogroup of all point
transformations on the natural bundle of equations
$y''=a^3(x,y)(y')^3+a^2(x,y)(y')^2+a^1(x,y)y'+a^0(x,y)$. We construct
differential invariants of this action and solve the equivalence problem for
some classes of these equations in particular for generic equations.


title: Sum rules and density wave spectrum for non relativistic fermions

abstract:
  Frequency sum rules are derived in extended quantum systems of non
relativistic fermions from a minimal set of assumptions on dynamics in infinite
volume, for ground and thermal states invariant under space translations or a
lattice subgroup. For the jellium Coulomb model, they imply the one point
result for the plasmon energy spectrum in the zero momentum limit. In general,
the density waves energy spectrum is shown to converge, in the limit of large
wavelenght, to a point measure at zero frequency, for any number of fermion
fields and potentials with integrable second derivatives. For low momentum,
<\omega^2(k)> ~ k^2 for potentials V with r^2 d_i d_j V integrable,
<\omega^2(k)> ~ k^{a-d+2} for potentials decaying at infinity as 1/r^a, d-2 < a
< d, d the space dimensions. For one component models with short range
interactions, the fourth momentum of the frequency is expressed, at lowest
order in k, purely in terms of the three point correlation function of the
density.


title:
Second-order asymptotic expansion for a non-synchronous covariation
  estimator

abstract:
  In this paper, we consider the problem of estimating the covariation of two
diffusion processes when observations are subject to non-synchronicity.
Building on recent papers \cite{Hay-Yos03, Hay-Yos04}, we derive second-order
asymptotic expansions for the distribution of the Hayashi-Yoshida estimator in
a fairly general setup including random sampling schemes and non-anticipative
random drifts. The key steps leading to our results are a second-order
decomposition of the estimator's distribution in the Gaussian set-up, a
stochastic decomposition of the estimator itself and an accurate evaluation of
the Malliavin covariance. To give a concrete example, we compute the constants
involved in the resulting expansions for the particular case of sampling scheme
generated by two independent Poisson processes.


title: A rigidity theorem for Moor-bialgebras

abstract:
  We introduce the operad Moor, dual of the operad NAP and the notion of
Moor-bialgebras. We warn the reader that the compatibility relation linking the
Moor-operation with the Moor-cooperation is not distributive in the sense of
Loday. Nevertheless, a rigidity theorem (\`a la Hopf-Borel) for the category of
connected Moor-bialgebras is given. We show also that free permutative algebras
can be equipped with a Moor-cooperation whose compatibility with the
permutative product looks like the infinitesimal relation.


title: Consistency of spectral clustering

abstract:
  Consistency is a key property of all statistical procedures analyzing
randomly sampled data. Surprisingly, despite decades of work, little is known
about consistency of most clustering algorithms. In this paper we investigate
consistency of the popular family of spectral clustering algorithms, which
clusters the data with the help of eigenvectors of graph Laplacian matrices. We
develop new methods to establish that, for increasing sample size, those
eigenvectors converge to the eigenvectors of certain limit operators. As a
result, we can prove that one of the two major classes of spectral clustering
(normalized clustering) converges under very general conditions, while the
other (unnormalized clustering) is only consistent under strong additional
assumptions, which are not always satisfied in real data. We conclude that our
analysis provides strong evidence for the superiority of normalized spectral
clustering.


title: Virial equation-of-state for the hard-disk fluid

abstract:
  Virial coefficients for the two-dimensional hard-disk fluid, when expressed
in powers of density relative to maximum close packing, lead to an accurate
closed equation-of-state for the equilibrium fluid, analogous to that recently
found for hard spheres. The 2D series also converges for all densities up to a
negative pole at close packing density. The virial pressure begins to deviate
from the thermodynamic fluid in the approach to the ordering transition.


title:
Spin-charge coupling in a band ferromagnet: magnon-energy reduction,
  anomalous softening, and damping

abstract:
  The effects of correlation-induced coupling between spin and charge
fluctuations on spin-wave excitations in a band ferromagnet are investigated by
including self-energy and vertex corrections within a systematic
inverse-degeneracy expansion scheme which explicitly preserves the Goldstone
mode. Arising from the scattering of a magnon into intermediate spin-excitation
states (including both magnon and Stoner excitations) accompanied with charge
fluctuations in the majority spin band, this spin-charge coupling results not
only in a substantial reduction of magnon energies but also in anomalous
softening and significant magnon damping for zone-boundary modes lying within
the Stoner gap. Our results are in good qualitative agreement with recent
spin-wave excitation measurements in colossal magneto-resistive manganites and
ferromagnetic ultrathin films of transition metals.


title: Improved Slater approximation to SIC-OEP

abstract:
  We propose a simplification of the Optimized Effective Potential (OEP)
applied to the Self Interaction Correction (SIC) scheme of Density Functional
Theory (DFT). The new scheme fulfills several key formal properties and turns
out to be both simple and accurate. We show examples of applications on model
molecules in terms of observables known to be especially sensitive to details
of the SIC-OEP approach.


title: Reverse Engineering of Proteasomal Translocation Rates

abstract:
  We address the problem of proteasomal protein translocation and introduce a
new stochastic model of the proteasomal digestion (cleavage) of proteins. In
this model we account for the protein translocation and the positioning of
cleavage sites of a proteasome from first principles. We show by test examples
and by processing experimental data that our model allows reconstruction of the
translocation and cleavage rates from mass spectroscopy data on digestion
patterns and can be used to investigate the properties of transport in
different experimental set-ups. Detailed investigation with this model will
enable theoretical quantitative prediction of the proteasomal activity.


title:
Accretion discs, low-mass protostars and planets: probing the impact of
  magnetic fields on stellar formation

abstract:
  Whereas the understanding of most phases of stellar evolution made
considerable progress throughout the whole of the twentieth century, stellar
formation remained rather enigmatic and poorly constrained by observations
until about three decades ago, when major discoveries (e.g., that protostars
are often associated with highly collimated jets) revolutionized the field. At
this time, it became increasingly clearer that magnetic fields were playing a
major role at all stages of stellar formation.
  We describe herein a quick overview of the main breakthroughs that
observations and theoretical modelling yielded for our understanding of how
stars (and their planetary systems) are formed and on how much these new worlds
are shaped by the presence of magnetic fields, either those pervading the
interstellar medium and threading molecular clouds or those produced through
dynamo processes in the convective envelopes of protostars or in the accretion
discs from which they feed.


title: Self-interaction correction in a simple model

abstract:
  We discuss various ways to handle self-interaction corrections (SIC) to
Density Functional Theory (DFT) calculations. To that end, we use a simple
model of few particles in a finite number of states together with a simple
zero-range interaction for which full Hartree-Fock can easily be computed as a
benchmark. The model allows to shed some light on the balance between
orthonormality of the involved states and energy variance.


title:
Electronic structure and heat transport in multivortex configurations in
  mesoscopic superconductors

abstract:
  On the basis of the Bogoliubov--de Gennes theory we study the transformation
of the quasiparticle spectrum in the mixed state of a mesoscopic
superconductor, governed by an external magnetic field. We analyze the low
energy part of the excitation spectrum and investigate the field--dependent
behavior of anomalous spectral branches crossing the Fermi level. Generalizing
the Caroli--de Gennes--Matricon approach we present an analytical solution
describing the anomalous branches in a vortex with an arbitrary winding number.
We also study the spectrum transformation caused by the splitting of a
multiquantum vortex into a set of well separated vortices focusing mainly on a
generic example of a two--vortex system. For vortices positioned rather close
to the sample surface we investigate the effect of the quasiparticle reflection
at the boundary on the spectrum and the density of states at the Fermi level.
Considering an arbitrary surface curvature we study the disappearance of an
anomalous spectral branch for a vortex leaving the sample. The changes in the
vortex configuration and resulting transformation of the anomalous branches are
shown to affect strongly the density of states and the heat conductance along
the magnetic field direction.


title:
Discrimination of two channels by adaptive methods and its application
  to quantum system

abstract:
  The optimal exponential error rate for adaptive discrimination of two
channels is discussed. In this problem, adaptive choice of input signal is
allowed. This problem is discussed in various settings. It is proved that
adaptive choice does not improve the exponential error rate in these settings.
These results are applied to quantum state discrimination.


title: Generalizations of product-free subsets

abstract:
  For any group G of order n, a subset A of G is said to be product-free if
there is no solution of the equation ab=c with a,b,c in A. Previous results of
Gowers showed that the size of any product-free subset of G is at most
n/d^(1/3), where d is the smallest dimension of a nontrivial representation of
G. However, this upper bound does not match the best lower bound. We will
generalize the upper bound to the case of product-poor subsets A, in which the
equation ab=c is allowed to have a few solutions with a,b,c in A. We prove that
the upper bound for the size of product-poor subsets matches the best lower
bound in many families of groups. We will also generalize the concept of
product-free to the case in which we have many subsets of a group, and
different constraints about products of the elements in the subsets.


title:
Spin-transfer switching and thermal stability in an FePt/Au/FePt
  nanopillar prepared by alternate monatomic layer deposition

abstract:
  We fabricated a current-perpendicular-to-plane giant magnetoresistance
(CPP-GMR) nanopillar with a 1-nm-thick FePt free layer having perpendicular
anisotropy using the alternate monatomic layer deposition method. Nanopillars
consisting of [Fe (1 monolayer (ML))/Pt (1 ML)]n (n: the number of the
alternation period) ferromagnetic layers and an Au spacer layer showed
spin-transfer induced switching at room temperature.


title:
Transverse rectification in density-modulated two-dimensional electron
  gases

abstract:
  We demonstrate tunable transverse rectification in a density-modulated
two-dimensional electron gas (2DEG). The density modulation is induced by two
surface gates, running in parallel along a narrow stripe of 2DEG. A transverse
voltage in the direction of the density modulation is observed, i.e.
perpendicular to the applied source-drain voltage. The polarity of the
transverse voltage is independent of the polarity of the source-drain voltage,
demonstrating rectification in the device. We find that the transverse voltage
$U_{y}$ depends quadratically on the applied source-drain voltage and
non-monotonically on the density modulation. The experimental results are
discussed in the framework of a diffusion thermopower model.


title: On the obstruction to integrability of almost-complex structures

abstract:
  The natural bundle $\pi:E\to M$ of almost-complex structures is considered.
The action of the pseudogroup of all diffeomorphisms of $M$ on the total space
$E$ is investigated. A nontrivial 1-st order differential invariant of this
action is constructed. It is proved that the Nijenhuise tensor of an
almost-complex structures is equal to zero iff the constructed invariant for
this structure is zero.


title:
Non-relativistic bound states at finite temperature (I): the hydrogen
  atom

abstract:
  We illustrate how to apply modern effective field theory techniques and
dimensional regularization to factorize the various scales which appear in
non-relativistic bound states at finite temperature. We focus here on the
simplest case: the hydrogen atom. We discuss in detail the interplay of the
hard, soft and ultrasoft scales of the non-relativistic system at zero
temperature with the additional scales induced at finite temperature. We also
comment on the implications of our results for heavy quarkonium bound states in
the quark gluon plasma.


title:
The Hubble constant from galaxy lenses: impacts of triaxiality and model
  degeneracies

abstract:
  The Hubble constant can be constrained using the time delays between multiple
images of gravitationally lensed sources. In some notable cases, typical
lensing analyses assuming isothermal galaxy density profiles produce low values
for the Hubble constant, inconsistent with the result of the HST Key Project
(72 +- 8 km/s/Mpc). Possible systematics in the values of the Hubble constant
derived from galaxy lensing systems can result from a number of factors, e.g.
neglect of environmental effects, assumption of isothermality, or contamination
by line-of-sight structures. One additional potentially important factor is the
triaxial structure of the lensing galaxy halo; most lens models account for
halo shape simply by perturbing the projected spherical lensing potential, an
approximation that is often necessary but that is inadequate at the levels of
triaxiality predicted in the CDM paradigm. To quantify the potential error
introduced by this assumption in estimates of the Hubble parameter, we strongly
lens a distant galaxy through a sample of triaxial softened isothermal halos
and use an MCMC method to constrain the lensing halo profile and the Hubble
parameter from the resulting multiple image systems. We explore the major
degeneracies between the Hubble parameter and several parameters of the lensing
model, finding that without a way to accurately break these degeneracies
accurate estimates of the Hubble parameter are not possible. Crucially, we find
that triaxiality does not significantly bias estimates of the Hubble constant,
and offer an analytic explanation for this behaviour in the case of isothermal
profiles. Neglected triaxial halo shape cannot contribute to the low Hubble
constant values derived in a number of galaxy lens systems.


title:
Asymptotic properties of bridge estimators in sparse high-dimensional
  regression models

abstract:
  We study the asymptotic properties of bridge estimators in sparse,
high-dimensional, linear regression models when the number of covariates may
increase to infinity with the sample size. We are particularly interested in
the use of bridge estimators to distinguish between covariates whose
coefficients are zero and covariates whose coefficients are nonzero. We show
that under appropriate conditions, bridge estimators correctly select
covariates with nonzero coefficients with probability converging to one and
that the estimators of nonzero coefficients have the same asymptotic
distribution that they would have if the zero coefficients were known in
advance. Thus, bridge estimators have an oracle property in the sense of Fan
and Li [J. Amer. Statist. Assoc. 96 (2001) 1348--1360] and Fan and Peng [Ann.
Statist. 32 (2004) 928--961]. In general, the oracle property holds only if the
number of covariates is smaller than the sample size. However, under a partial
orthogonality condition in which the covariates of the zero coefficients are
uncorrelated or weakly correlated with the covariates of nonzero coefficients,
we show that marginal bridge estimators can correctly distinguish between
covariates with nonzero and zero coefficients with probability converging to
one even when the number of covariates is greater than the sample size.


title: Observations of CO in the eastern filaments of NGC 1275

abstract:
  We recently found extended CO(2-1) emission from cold molecular gas embedded
in the network of Halpha filaments surrounding the galaxy NGC 1275 (Salome et
al. 2006). We now present CO(2-1) interferometer maps of the eastern filaments,
at high spatial and spectral resolutions. The cold molecular gas is detected by
the Plateau de Bure Interferometer along the eastern filaments over an extent
of 15'', or with a projected length of 5kpc. In our 2.5'' beam, the main CO
filament is mostly unresolved along its minor axis. The multiple peaks along
the CO filaments and the low values of the observed CO brightness temperatures
imply further unresolved structures that may be giant molecular clouds. These
clouds have very narrow line-width emission lines (~30 km/s). The CO emission
is optically thick. It very likely traces cold clouds bound under their own
self-gravity that may be falling back in the gravitational potential well of
the galaxy. Such a picture would agree with current models of ``positive
feedback'' in which some of the hot gas around NGC 1275 (a) is trapped by
buoyantly rising bubbles inflated by the energy input of the 3C84 AGN, (b)
subsequently cools efficiently at a larger radius around the edges of the hot
bubbles, and (c) then falls back in self-gravitating clouds of molecular gas
toward the center of the galaxy.


title: A 3-manifold complexity via immersed surfaces

abstract:
  We define an invariant, which we call surface-complexity, of closed
3-manifolds by means of Dehn surfaces. The surface-complexity of a manifold is
a natural number measuring how much the manifold is complicated. We prove that
it fulfils interesting properties: it is subadditive under connected sum and
finite-to-one on P2-irreducible manifolds. Moreover, for P2-irreducible
manifolds, it equals the minimal number of cubes in a cubulation of the
manifold, except for the sphere S3, the projective space RP3 and the lens space
L41, which have surface-complexity zero. We will also give estimations of the
surface-complexity by means of triangulations, Heegaard splittings, surgery
presentations and Matveev complexity.


title:
Inference of genetic networks from time course expression data using
  functional regression with lasso penalty

abstract:
  Statistical inference of genetic regulatory networks is essential for
understanding temporal interactions of regulatory elements inside the cells.
For inferences of large networks, identification of network structure is
typical achieved under the assumption of sparsity of the networks.
  When the number of time points in the expression experiment is not too small,
we propose to infer the parameters in the ordinary differential equations using
the techniques from functional data analysis (FDA) by regarding the observed
time course expression data as continuous-time curves. For networks with a
large number of genes, we take advantage of the sparsity of the networks by
penalizing the linear coefficients with a L_1 norm. The ability of the
algorithm to infer network structure is demonstrated using the cell-cycle time
course data for Saccharomyces cerevisiae.


title: A tachyon lump in closed string field theory

abstract:
  We find a codimension one lump solution of closed bosonic string field
theory. We consider vertices up to quartic order and include in the string
field the tachyon, the ghost dilaton, and a metric fluctuation. While the
tachyon profile clearly is that of a lump, we observe that the ghost dilaton is
roughly constant in the direction transverse to the lump, equal to the value it
takes in the nonperturbative tachyon vacuum. We explain, with a simple model,
why this should be expected.


title: Orbit of Binary 15 Monocerotis

abstract:
  In the paper new orbital elements obtained from speckle interferometric
measurements only for 15 Mon are reported. For this binary they were determined
earlier by combining spectroscopic and speckle measurements and spectroscopic
and astrometric measurements. A new speckle measurement dating after the
periastron passage of the secondary has a significant discrepancy from the
ephemeridal value. Our revised orbit has a period significantly longer than the
earlier ones. With regard that in the case of the earlier orbits the period was
determined from spectroscopic measurements, i.e. from radial velocity data, the
existing data of such kind for this binary are analyzed here and combined with
our orbital elements. The first speckle measurement originates from 1988 and up
to now three more speckle measurements have been made. This pair is bright
(apparent magnitude of primary 4.66, i.e. 5.9 of secondary), of an early
spectral type (primary O7V, secondary O9.5Vn) and is a member of open cluster
NGC 2264. The distance to this cluster has been determined many times and
different values have been reported. By analyzing the available data we find
that the distance to 15 Mon is most likely about 750 pc, i.e. the total mass
most likely about 53.4${\cal M}_{\odot}$. The new orbital elements combined
with this distance yield a total mass expected for the spectral types of the
components.


title:
Self-indexing energy function for Morse-Smale diffeomorphisms on
  3-manifolds

abstract:
  The paper is devoted to finding conditions to the existence of a
self-indexing energy function for Morse-Smale diffeomorphisms on a 3-manifold.
These conditions involve how the stable and unstable manifolds of saddle points
are embedded in the ambient manifold. We also show that the existence of a
self-indexing energy function is equivalent to the existence of a Heegaard
splitting of a special type with respect to the considered diffeomorphism.


title: About Adaptive Singular Systems with External Delay

abstract:
  This paper is mainly concerned with the robustly stable adaptive control of
single-input single-output impulse-free linear time-invariant singular dynamic
systems of known order and unknown parameterizations subject to single external
point delays. The control law is of pole-placement type and based on
input/output measurements and parametrical estimation only. The parametrical
estimation incorporates adaptation dead zones to prevent against potential
instability caused by disturbances and unmodeled dynamics. The Weierstrass
canonical form is investigated in detail to discuss controllability and
observability via testable conditions of the given arbitrary state-space
realization of the same order.


title: A_k singularities of wave fronts

abstract:
  In this paper, we discuss the recognition problem for A_k-type singularities
on wave fronts. We give computable and simple criteria of these singularities,
which will play a fundamental role in generalizing the authors' previous work
"the geometry of fronts" for surfaces. The crucial point to prove our criteria
for A_k-singularities is to introduce a suitable parametrization of the
singularities called the "k-th KRSUY-coordinates". Using them, we can directly
construct a versal unfolding for a given singularity. As an application, we
prove that a given nondegenerate singular point p on a real (resp. complex)
hypersurface (as a wave front) in R^{n+1} (resp. C^{n+1}) is differentiably
(resp. holomorphically) right-left equivalent to the A_{k+1}-type singular
point if and only if the linear projection of the singular set around p into a
generic hyperplane R^n (resp. C^n) is right-left equivalent to the A_k-type
singular point in R^n (resp. C^{n}). Moreover, we show that the restriction of
a C-infinity-map f:R^n --> R^n to its Morin singular set gives a wave front
consisting of only A_k-type singularities. Furthermore, we shall give a
relationship between the normal curvature map and the zig-zag numbers (the
Maslov indices) of wave fronts.


title:
Effect of pair-breaking on mesoscopic persistent currents well above the
  superconducting transition temperature

abstract:
  We consider the mesoscopic normal persistent current (PC) in a very
low-temperature superconductor with a bare transition temperature $T_c^0$ much
smaller than the Thouless energy $E_c$. We show that in a rather broad range of
pair-breaking strength, $T_c^0 \lesssim \hbar/\tau_s \lesssim E_c$, the
transition temperature is renormalized to zero, but the PC is hardly affected.
This may provide an explanation for the magnitude of the average PC's in the
noble metals, as well as a way to determine their $T_c^0$'s.


title: High-dimensional generalized linear models and the lasso

abstract:
  We consider high-dimensional generalized linear models with Lipschitz loss
functions, and prove a nonasymptotic oracle inequality for the empirical risk
minimizer with Lasso penalty. The penalty is based on the coefficients in the
linear predictor, after normalization with the empirical norm. The examples
include logistic regression, density estimation and classification with hinge
loss. Least squares regression is also discussed.


title: Admissible submonoids of Artin-Tits monoids

abstract:
  We show the analogue of Muhlherr's [Coxeter groups in Coxeter groups, Finite
Geom. and Combinatorics, Cambridge Univ. Press (1993), 277-287] for Artin-Tits
monoids, and for Artin-Tits groups of spherical type. That is, the submonoid
(resp. subgroup) of an Artin-Tits monoid (resp. group of spherical type)
induced by an admissible partition of the Coxeter graph is an Artin-Tits monoid
(resp. group). This generalizes and unifies the situation of the submonoid
(resp. subgroup) of fixed elements of an Artin-Tits monoid (resp. group of
spherical type) under the action of graph automorphisms, and the notion of
LCM-homomorphisms defined by Crisp in [Injective maps between Artin groups,
Geom. Group Theory Down Under, Canberra (1996) 119-137] and generalized by
Godelle in [Morphismes injectifs entre groupes d'Artin-Tits, Algebr. Geom.
Topol. 2 (2002), 519--536]. We then complete the classification of the
admissible partitions for which the Coxeter graphs involved have no infinite
label, started by Muhlherr in [Some contributions to the theory of buildings
based on the gate property, Dissertation, T\"ubingen (1994)]. This leads us to
the classification of Crisp's LCM-homomorphisms.


title: Weak Finsler Strutures and the Funk Metric

abstract:
  We discuss general notions of metrics and of Finsler structures which we call
weak metrics and weak Finsler structures. Any convex domain carries a canonical
weak Finsler structure, which we call its tautological weak Finsler structure.
We compute distances in the tautological weak Finsler structure of a domain and
we show that these are given by the so-called Funk weak metric. We conclude the
paper with a discussion of geodesics, of metric balls and of convexity
properties of the Funk weak metric.


title: Moves for standard skeleta of 3-manifolds with marked boundary

abstract:
  We prove that the classical set of moves for standard spines of 3-manifolds
(i.e. the MP-move and the V-move) does not suffice to relate to each other any
two standard skeleta of a 3-manifold with marked boundary. We also describe a
condition on the 3-manifold with marked boundary that tells whether the
generalised set of moves, made up of the MP-move and the L-move, suffices to
relate to each other any two standard skeleta of the 3-manifold with marked
boundary.
  For the 3-manifolds with marked boundary that do not fulfil this condition,
we give three other moves: the CR-move, the T1-move and the T2-move. The first
one is local and, with the MP-move and the L-move, suffices to relate to each
other any two standard skeleta of a 3-manifold with marked boundary fulfilling
another condition. For the universal case, we prove that the non-local T1-move
and T2-move, with the MP-move and the L-move, suffice to relate to each other
any two standard skeleta of a generic 3-manifold with marked boundary.
  As a corollary, we get that disc-replacements suffice to relate to each other
any two standard skeleta of a 3-manifold with marked boundary.


title: Viscous Fingering-like Instability of Cell Fragments

abstract:
  We present a novel flow instability that can arise in thin films of
cytoskeletal fluids if the friction with the substrate on which the film lies
is sufficiently strong. We consider a two dimensional, membrane-bound fragment
containing actin filaments that is perturbed from its initially circular state,
where actin polymerizes at the edge and flows radially inward while
depolymerizing in the fragment. Performing a linear stability analysis of the
initial state due to perturbations of the fragment boundary, we find, in the
limit of very large friction, that the perturbed actin velocity and pressure
fields obey the very same laws governing the viscous fingering instability of
an interface between immiscible fluids in a Hele-Shaw cell. A feature of this
instability that is remarkable in the context of cell motility, is that its
existence is independent of the strength of the interaction between
cytoskeletal filaments and myosin motors, and moreover that it is completely
driven by the free energy of actin polymerization at the fragment edge.


title:
Ultra-High-Energy Cosmic Rays from a Magnetized Strange Star Central
  Engine for Gamma-Ray Bursts

abstract:
  Ultra-high-energy cosmic rays (UHECRs) have been tried to be related to the
most varied and powerful sources known in the universe. Gamma-ray bursts (GRBs)
are natural candidates. Here, we argue that cosmic rays can be accelerated by
large amplitude electromagnetic waves (LAEMWs) when the MHD approximation of
the field in the wind generated by the GRB's magnetized central engine breaks
down. The central engine considered here is a strange star born with
differential rotation from the accretion induced conversion of a neutron star
into a strange star in a low-mass X-ray binary system. The LAEMWs generated
this way accelerate light ions to the highest energies $E =
q\eta\Delta\Phi_{max}$ with an efficiency $\eta \sim 10^{-1}$ that accounts for
all plausible energy losses. Alternatively, we also consider the possibility
that, once formed, the LAEMWs are unstable to creation of a relativistically
strong electromagnetic turbulence due to an overturn instability. Under this
assumption, a lower limit to the efficiency of acceleration is estimated to be
about $\eta \sim 10^{-2.5}$. Due to their age, low mass X-ray binary systems
can be located in regions of low interstellar medium density as, e.g., globular
clusters or even intergalactic medium in case of high proper motion systems,
and cosmic ray energy losses due to proton collisions with photons at the
decelerating region are avoided, thus opening the possibility for particles to
exploit the full voltage available, well beyond that currently observed.


title:
Effect of mean on variance function estimation in nonparametric
  regression

abstract:
  Variance function estimation in nonparametric regression is considered and
the minimax rate of convergence is derived. We are particularly interested in
the effect of the unknown mean on the estimation of the variance function. Our
results indicate that, contrary to the common practice, it is not desirable to
base the estimator of the variance function on the residuals from an optimal
estimator of the mean when the mean function is not smooth. Instead it is more
desirable to use estimators of the mean with minimal bias. On the other hand,
when the mean function is very smooth, our numerical results show that the
residual-based method performs better, but not substantial better than the
first-order-difference-based estimator. In addition our asymptotic results also
correct the optimal rate claimed in Hall and Carroll [J. Roy. Statist. Soc.
Ser. B 51 (1989) 3--14].


title:
Two Qubit Entanglement in Magnetic Chains with DM Antisymmetric
  Anisotropic Exchange Interaction

abstract:
  In the present paper an influence of the anisotropic antisymmetric exchange
interaction, the Dzialoshinskii-Moriya (DM) interaction, on entanglement of two
qubits in various magnetic spin models, including the pure DM model and the
most general XYZ model are studied. We find that the time evolution generated
by DM interaction can implement the SWAP gate and discuss realistic
quasi-one-dimensional magnets where it can be realized. It is shown that
inclusion of the DM interaction to any Heisenberg model creates, when it does
not exist, or strengthens, when it exists, the entanglement. We give physical
explanation of these results by studying the ground state of the systems at
T=0. Nonanalytic dependence of the concurrence on the DM interaction and its
relation with quantum phase transition is indicated. Our results show that spin
models with the DM coupling have some potential applications in quantum
computations and the DM interaction could be an efficient control parameter of
entanglement.


title: The evolution of Ap stars

abstract:
  The many peculiarities of Ap stars (not only chemical ones, but also magnetic
field and slow rotation) may vary during the main-sequence evolution of these
stars. We review here briefly the evidences found in the last thirty years for
such evolution, with an emphasis on the more recent research. The position in
the HR diagram of low mass Ap stars with a significant surface magnetic field
(as measured by us) is reviewed as well.


title:
Elastic properties of quaternary oxyarsenide LaOFeAs as basic phase for
  new 26-52K superconductors

abstract:
  The full-potential linearized augmented plane wave (FP-LAPW) method with the
generalized gradient approximation (GGA) for the exchange-correlation potential
has been applied to predict the elastic properties of quaternary oxyarsenide
LaOFeAs - the basic phase for the newly discovered 26-52K superconductors. The
optimized lattice parameters, independent elastic constants (Cij), bulk modulus
B, compressibility betta, and shear modulus G are evaluated and discussed. For
the first time the numerical estimates of the elastic parameters for
polycrystalline LaOFeAs ceramics are performed. Our analysis shows that LaOFeAs
belong to the anisotropic mechanically stable systems; a parameter limiting the
mechanical stability of this material is the shear modulus. In addition,
LaOFeAs is a soft material (B -98 GPa) with high compressibility (betta -
0.0102 1/GPa); lays at the border of a brittle behavior and adopts a high ionic
contribution in intra-atomic bonding.