title: Quantum Brownian Motion of a Macroscopic Object in a General Environment

abstract:
  For the purpose of understanding the quantum behavior such as quantum
decoherence, fluctuations, dissipation, entanglement and teleportation of a
mesoscopic or macroscopic object interacting with a general environment, we
derive here a set of exact master equations for the reduced density matrix of
$N$ interacting harmonic oscillators in a heat bath with arbitrary spectral
density and temperature. Two classes of problems of interest to us which these
equations can be usefully applied to are that of the quantum dynamics of
nanoelectromechanical oscillators and the entanglement evolution of
multi-partite macroscopic states such as quantum superposition of mirrors in a
high Q cavity. To address a key conceptual issue for macroscopic quantum
phenomena we examine the conditions for an assumption often implicitly made in
these studies to be valid, namely, that the quantum behavior of a macroscopic
object in an environment can be accurately represented by only treating the
dynamics of its center-of-mass variable. We also mention how these results can
be used to calculate the uncertainty principle governing a macroscopic object
at finite temperature.


title:
The complete LQG propagator: I. Difficulties with the Barrett-Crane
  vertex

abstract:
  Some components of the graviton two-point function have been recently
computed in the context of loop quantum gravity, using the spinfoam
Barrett-Crane vertex. We complete the calculation of the remaining components.
We find that, under our assumptions, the Barrett-Crane vertex does not yield
the correct long distance limit. We argue that the problem is general and can
be traced to the intertwiner-independence of the Barrett-Crane vertex, and
therefore to the well-known mismatch between the Barrett-Crane formalism and
the standard canonical spin networks. In a companion paper we illustrate the
asymptotic behavior of a vertex amplitude that can correct this difficulty.


title: A New Model of Agegraphic Dark Energy

abstract:
  In this note, we propose a new model of agegraphic dark energy based on the
K\'{a}rolyh\'{a}zy relation, where the time scale is chosen to be the conformal
time $\eta$ of the Friedmann-Robertson-Walker (FRW) universe. We find that in
the radiation-dominated epoch, the equation-of-state parameter of the new
agegraphic dark energy $w_q=-1/3$ whereas $\Omega_q=n^2a^2$; in the
matter-dominated epoch, $w_q=-2/3$ whereas $\Omega_q=n^2a^2/4$; eventually, the
new agegraphic dark energy dominates; in the late time $w_q\to -1$ when
$a\to\infty$, and the new agegraphic dark energy mimics a cosmological
constant. In every stage, all things are consistent. The confusion in the
original agegraphic dark energy model proposed in arXiv:0707.4049 disappears in
this new model. Furthermore, $\Omega_q\ll 1$ is naturally satisfied in both
radiation-dominated and matter-dominated epochs where $a\ll 1$. In addition, we
further extend the new agegraphic dark energy model by including the
interaction between the new agegraphic dark energy and background matter. In
this case, we find that $w_q$ can cross the phantom divide.


title:
Massive Lyman Break Galaxies at z~3 in the Spitzer Extragalactic First
  Look Survey

abstract:
  We investigate the properties of 1088 Lyman Break Galaxies (LBGs) at z~3
selected from a ~2.63$ deg2 sub-region of the First Look Survey field using the
ground-based multi-color data and the Spitzer Space Telescope mid-infrared data
at 3--8 and 24 um. With the wide area and the broad wavelength coverage, we
sample a large number of ``rare'' u-band dropouts which are massive (M* > 10^11
Msun), allowing us to perform a statistical analysis of these subsets of LBGs
that have not been studied in detail. Optically bright (R(AB) < 24.5 mag) LBGs
detected in mid-infrared (S_{3.6um} > 6 uJy) reside at the most massive and
dusty end of the LBG population, with relatively high and tight $M/L$ in
rest-frame near-infrared. Most infrared-luminous LBGs (S_{24um} > 100 uJy) are
dusty star-forming galaxies with star formation rates of 100--1000 Msun/yr,
total infrared luminosity of > 10^12 Lsun. By constructing the UV luminosity
function of massive LBGs, we estimate that the lower limit for the star
formation rate density from LBGs more massive than 10^11 Msun at z~3 is > 3.3 x
10^-3 Msun/yr/Mpc^3, showing for the first time that the UV-bright population
of massive galaxies alone contributes significantly to the global star
formation rate density at z~3. When combined with the star formation rate
densities at z < 2, our result reveals a steady increase in the contribution of
massive galaxies to the global star formation from z=0 to z=3, providing strong
support to the downsizing of galaxy formation.


title:
Deep u*- and g-band Imaging of the Spitzer Space Telescope First Look
  Survey Field : Observations and Source Catalogs

abstract:
  We present deep u*-, and g-band images taken with the MegaCam on the 3.6 m
Canada-France-Hawaii Telescope (CFHT) to support the extragalactic component of
the Spitzer First Look Survey (hereafter, FLS). In this paper we outline the
observations, present source catalogs and characterize the completeness,
reliability, astrometric accuracy and number counts of this dataset. In the
central 1 deg2 region of the FLS, we reach depths of g~26.5 mag, and u*~26.2
mag (AB magnitude, 5$\sigma$ detection over a 3" aperture) with ~4 hours of
exposure time for each filter. For the entire FLS region (~5 deg2 coverage), we
obtained u*-band images to the shallower depth of u*=25.0--25.4 mag (5$\sigma$,
3" aperture). The average seeing of the observations is 0.85" for the central
field, and ~1.00" for the other fields. Astrometric calibration of the fields
yields an absolute astrometric accuracy of 0.15" when matched with the SDSS
point sources between 18<g<22. Source catalogs have been created using
SExtractor. The catalogs are 50% complete and greater than 99.3% reliable down
to g~26.5 mag and u*~26.2 mag for the central 1 deg2 field. In the shallower
u*-band images, the catalogs are 50% complete and 98.2% reliable down to
24.8--25.4 mag. These images and source catalogs will serve as a useful
resource for studying the galaxy evolution using the FLS data.


title:
Volume-preserving mean curvature flow of revolution hypersurfaces in a
  Rotationally Symmetric Space

abstract:
  In an ambient space with rotational symmetry around an axis (which include
the Hyperbolic and Euclidean spaces), we study the evolution under the
volume-preserving mean curvature flow of a revolution hypersurface M generated
by a graph over the axis of revolution and with boundary in two totally
geodesic hypersurfaces (tgh for short). Requiring that, for each time t, the
evolving hypersurface M_t meets such tgh ortogonally, we prove that: a) the
flow exists while M_t does not touch the axis of rotation; b) throughout the
time interval of existence, b1) the generating curve of M_t remains a graph,
and b2) the averaged mean curvature is double side bounded by positive
constants; c) the singularity set (if non-empty) is finite and discrete along
the axis; d) under a suitable hypothesis relating the enclosed volume to the
n-volume of M, we achieve long time existence and convergence to a revolution
hypersurface of constant mean curvature.


title: An Action For Chan-Paton Factors

abstract:
  We show that Chan-Paton factors can be derived from a classical action
describing the dynamics of a new group-valued degree of freedom attached to the
boundary of an open bosonic string. We discuss the free and the interacting
string in the oriented and unoriented cases, as well as the coupling of the
string to an external Yang-Mills gauge field, and recover by this approach
well-known results.


title:
Improved Photometric Calibrations for Red Stars Observed with the SDSS
  Photometric Telescope

abstract:
  We present a new set of photometric transformations for red stars observed
with the Sloan Digital Sky Survey (SDSS) 0.5-m Photometric Telescope (PT) and
the SDSS 2.5-m telescope at the Apache Point Observatory in New Mexico. Nightly
PT observations of US Naval Observatory standards are used to determine
extinction corrections and calibration terms for SDSS 2.5-m photometry.
Systematic differences between the PT and native SDSS 2.5-m {\it ugriz}
photometry require conversions between the two systems which have previously
been undefined for the reddest stars. By matching $\sim 43,000$ stars observed
with both the PT and SDSS 2.5-m, we extend the present relations to include
low-mass stars with colors $0.6 \le r-i \le 1.7$. These corrections will allow
us to place photometry of bright, low-mass trigonometric parallax stars
previously observed with the PT on the 2.5-m system. We present new
transformation equations and discuss applications of these data to future
low-mass star studies using the SDSS.


title:
Operational Semantics and Type Soundness of Quantum Programming Language
  LanQ

abstract:
  We present an imperative quantum programming language LanQ which was designed
to support combination of quantum and classical programming and basic process
operations - process creation and interprocess communication. The language can
thus be used for implementing both classical and quantum algorithms and
protocols. Its syntax is similar to that of C language what makes it easy to
learn for existing programmers. In this paper, we present operational semantics
of the language and a proof of type soundness of the noncommunicating part of
the language. We provide an example run of a quantum random number generator.


title: Operad of formal homogeneous spaces and Bernoulli numbers

abstract:
  It is shown that for any morphism, i: g --> h, of Lie algebras the vector
space underlying the Lie algebra h is canonically a g-homogeneous formal
manifold with the action of g being highly nonlinear and twisted by Bernoulli
numbers. This fact is obtained from the study of a 2-coloured operad of formal
homogeneous spaces and its minimal resolution, and is used to give a new
conceptual explanation of both Ziv Ran's Jacobi-Bernoulli complex and
Fiorenza-Manetti's L-infinity algebra structure on the mapping cone of a
morphism of two Lie algebras. All these constructions are iteratively extended
to the case of a morphism of arbitrary L-infinity algebras.


title: Nonlinear screening and ballistic transport in a graphene p-n junction

abstract:
  We study the charge density distribution, the electric field profile, and the
resistance of an electrostatically created lateral p-n junction in graphene. We
show that the electric field at the interface of the electron and hole regions
is strongly enhanced due to limited screening capacity of Dirac quasiparticles.
Accordingly, the junction resistance is lower than estimated in previous
literature.


title: Uniform Sobolev inequalities for manifolds evolving by Ricci flow

abstract:
  Let M be a compact n-dimensional manifold, $n\ge 2$, with metric g(t)
evolving by the Ricci flow $\partial g_{ij}/\partial t=-2R_{ij}$ in (0,T) for
some $T\in\Bbb{R}^+\cup\{\infty\}$ with $g(0)=g_0$. Let $\lambda_0(g_0)$ be the
first eigenvalue of the operator $-\Delta_{g_0} +\frac{R(g_0)}{4}$ with respect
to g_0. We extend a recent result of R. Ye and prove uniform logarithmic
Sobolev inequality and uniform Sobolev inequalities along the Ricci flow for
any $n\ge 2$ when either $T<\infty$ or $\lambda_0(g_0)>0$. As a consequence we
extend Perelman's local $\kappa$-noncollapsing result along the Ricci flow for
any $n\ge 2$ in terms of upper bound for the scalar curvature when either
$T<\infty$ or $\lambda_0(g_0)>0$.


title:
Density-Matrix Renormalization Group Study of Trapped Imbalanced Fermi
  Condensates

abstract:
  The density-matrix renormalization group is employed to investigate a
harmonically-trapped imbalanced Fermi condensate based on a one-dimensional
attractive Hubbard model. The obtained density profile shows a flattened
population difference of spin-up and spin-down components at the center of the
trap, and exhibits phase separation between the condensate and unpaired
majority atoms for a certain range of the interaction and population imabalance
$P$. The two-particle density matrix reveals that the sign of the order
parameter changes periodically, demonstrating the realization of the
Fulde-Ferrell-Larkin-Ovchinnikov phase. The minority spin atoms contribute to
the quasi-condensate up to at least $P \simeq 0.8$. Possible experimental
situations to test our predictions are discussed.


title:
Generation and detection of non-Abelian matrix Berry phases through
  manipulation of electric confinement potential of a semiconductor quantum dot

abstract:
  A matrix Berry phase can be generated and detected by {\it all electric
means} in II-VI or III-V n-type semiconductor quantum dots by changing the
shape of the confinement potential. This follows from general symmetry
considerations in the presence of spin-orbit coupling terms. The resulting 2 x
2 matrix Berry phase can be characterized by two numbers of geometric origin.
We investigate how these parameters depend on the shape and area of closed
adiabatic paths. We suggest how the matrix Berry phase may be detected in
transport measurements.


title:
Long term dynamics of the splitting of a doubly quantized vortex in a
  two-dimensional condensate

abstract:
  We study the nonlinear dynamics of the splitting of a doubly quantized vortex
in a trapped condensate. The dynamics is studied in detail by solving the
Gross-Pitaevskii equation. The main dynamical features are explained in terms
of a nonlinear three-level system. We find an analytical solution for the
characteristics of the dynamics. It is concluded that the time scale for the
splitting is mainly determined by the instability of the linearized system, and
nonlinear effects contribute logarithmically.


title: Brane World Inflation with Scalar and Tachyon Fields

abstract:
  We present inflationary models of the early universe in the braneworld
scenario considering both scalar field and tachyon field separately. The
technique of Chervon and Zhuravlev to obtain inflationary cosmological models
without restrictions on a scalar field potential is employed here. We note that
like scalar field, the inflationary solution obtained here with tachyon field
also does not depend on its potential. However, unlike scalar field, inflation
with tachyon is obtained for a restricted domains of the field to begin with.
We obtain potentials for which one gets inflation using both scalar field and
tachyon field separately. It is found that unlike the scalar field, the
tachyonic field inflation sceanario can be realized from t > t_o.


title:
Optimisation of the 3-body dynamics applied to extra-solar planetary
  systems

abstract:
  The body of work presented here revolves around the investigation of the
existence and nature of extra-solar planetary systems. The fitting of stellar
radial velocity time series data is attempted by constructing a model to
quantify the orbital properties of a star-planetary system. This is achieved
with the Planetary Orbit Fitting Process (POFP). Though specific to the
investigated problem, the POFP is founded on two separate, more general ideas.
One is a Solver producing the gravitational dynamics of a Three-Body system by
integrating its Newtonian equations of motion. The other is an independent
optimisation scheme. Both have been devised using MATLAB. Applying the
optimisation to the Solver results in a realistic Three-Body dynamics that best
describes the radial velocity data under the model-specific
orbital-observational constraints. Combining these aspects also allows for the
study of dynamical instability derived from interaction, which is reaffirmed as
a necessary criterion for evaluating the fit. The validity of POFP solutions
with respect to the observations and other models is discussed in this context.
The underlying generality and fundamental principles demonstrate a larger frame
of operation where problems in Physics and Mathematics can be solved with a
multitude of techniques.


title: Self-similar carpets over finite fields

abstract:
  Some linear dynamical systems over finite fields are studied and the
self-similar character of their development is proved. Connections with
aperiodic tilings, Delanoy numbers and other topics are also proved. The prime
fields F_p have a canonical presentation as sets of self-similar carpets. The
multiplicative inverse corresponds to mirroring.


title:
Spin-down of compact stars and energy release of a first-order phase
  transition

abstract:
  The deconfinement phase transition from hadronic matter to quark matter can
continuously occur during spins down of neutron stars. It will lead to the
release of latent heat if the transition is the first-order one. We have
investigated the energy release of such deconfinement phase transition for
rotating hybrid stars model which include mixed phase of hadronic matter and
quark matter. The release of latent heat per baryon is calculated through
studying a randomly process of infinitesimal compressing. Finally, we can
self-consistently get the heating luminosity of deconfinement phase transition
by imputing the EOS of mixed phase, and based on the equation of rotation
structure of stars.


title:
The Statistical Mechanics of Microscopic Long-Range Bulk-Boundary
  Dependence in Black-Hole Physics and Holography

abstract:
  We argue in the following that the entropy-area law of black-hole physics and
the various holographic bounds are the consequences of the microscopic dynamics
of elementary degrees of freedom living on or near the Planck scale. We locate
them both in the interior and on the boundary of, for example, the black hole
with the strange area-behavior of various quantities being the result of a
long-range bulk-boundary dependence among these degrees of freedom. In contrast
to other approaches we regard the vacuum fluctuations on microscopic scales as
the relevant elementary building blocks. In so far certain relations to to old
ideas of Sakharov, Zeldovich et al are acknowledged (induced gravity). Most
importantly, we prove that the existence of a large energy gap between a few
low-lying excitation patterns and the majority of the other (in principle)
possible excitation patterns in a subvolume with given boundary excitation is
crucial for this area-dependence. We also remark that this is an indication
that some particular entangled space-time geometry of a somewhat non-local
character prevails in the microscopic (Planck) regime. Our findings are
corroborated by the explanation of a number of open questions in the field (see
the table of contents at the end of the introduction).


title: Quantum multiparty key distribution protocol without use of entanglement

abstract:
  We propose a quantum key distribution (QKD) protocol that enables three
parties agree at once on a shared common random bit string in presence of an
eavesdropper without use of entanglement. We prove its unconditional security
and analyze the key rate.


title: Percolation of Vortices in the 3D Abelian Lattice Higgs Model

abstract:
  The compact Abelian Higgs model is simulated on a cubic lattice where it
possesses vortex lines and pointlike magnetic monopoles as topological defects.
The focus of this high-precision Monte Carlo study is on the vortex network,
which is investigated by means of percolation observables. In the region of the
phase diagram where the Higgs and confinement phases are separated by a
first-order transition, it is shown that the vortices percolate right at the
phase boundary, and that the first-order nature of the transition is reflected
by the network. In the crossover region, where the phase boundary ceases to be
first order, the vortices are shown to still percolate. In contrast to other
observables, the percolation observables show finite-size scaling. The
exponents characterizing the critical behavior of the vortices in this region
are shown to fall in the random percolation universality class.


title:
Improving HTc Josephson Junctions (HTc JJ) by annealing: the role of
  vacancy-interstitial annihilation

abstract:
  We have studied the annealing effect in transport properties of High
temperature Josephson Junctions (HTc JJ) made by ion irradiation. Low
temperature annealing (80 degrees Celsius) increases the JJ transition
temperature (TJ) and the Ic.Rn product, where Ic is the critical current and Rn
the normal resistance. We found that the spread in JJ characteristics can be
lowered by sufficient long annealing times. Using random walk numerical
simulations, we showed that the characteristic annealing time and the evolution
of the spread in JJ characteristics can be explained by a vacancy-interstitial
annihilation process rather than by an oxygen diffusion one.


title:
Permutation Decoding and the Stopping Redundancy Hierarchy of Cyclic and
  Extended Cyclic Codes

abstract:
  We introduce the notion of the stopping redundancy hierarchy of a linear
block code as a measure of the trade-off between performance and complexity of
iterative decoding for the binary erasure channel. We derive lower and upper
bounds for the stopping redundancy hierarchy via Lovasz's Local Lemma and
Bonferroni-type inequalities, and specialize them for codes with cyclic
parity-check matrices. Based on the observed properties of parity-check
matrices with good stopping redundancy characteristics, we develop a novel
decoding technique, termed automorphism group decoding, that combines iterative
message passing and permutation decoding. We also present bounds on the
smallest number of permutations of an automorphism group decoder needed to
correct any set of erasures up to a prescribed size. Simulation results
demonstrate that for a large number of algebraic codes, the performance of the
new decoding method is close to that of maximum likelihood decoding.


title: Spectroscopic analysis of finite size effects around a Kondo quantum dot

abstract:
  We consider a simple setup in which a small quantum dot is strongly connected
to a finite size box. This box can be either a metallic box or a finite size
quantum wire.The formation of the Kondo screening cloud in the box strongly
depends on the ratio between the Kondo temperature and the box level spacing.
By weakly connecting two metallic reservoirs to the quantum dot, a detailed
spectroscopic analysis can be performed. Since the transport channels and the
screening channels are almost decoupled, such a setup allows an easier access
to the measure of finite-size effects associated with the finite extension of
the Kondo cloud.


title: Permanents of Circulants: a Transfer Matrix Approach (Expanded Version)

abstract:
  Calculating the permanent of a (0,1) matrix is a #P-complete problem but
there are some classes of structured matrices for which the permanent is
calculable in polynomial time. The most well-known example is the fixed-jump
(0,1) circulant matrix which, using algebraic techniques, was shown by Minc to
satisfy a constant-coefficient fixed-order recurrence relation.
  In this note we show how, by interpreting the problem as calculating the
number of cycle-covers in a directed circulant graph, it is straightforward to
reprove Minc's result using combinatorial methods. This is a two step process:
the first step is to show that the cycle-covers of directed circulant graphs
can be evaluated using a transfer matrix argument. The second is to show that
the associated transfer matrices, while very large, actually have much smaller
characteristic polynomials than would a-priori be expected.
  An important consequence of this new viewpoint is that, in combination with a
new recursive decomposition of circulant-graphs, it permits extending Minc's
result to calculating the permanent of the much larger class of circulant
matrices with non-fixed (but linear) jumps. It also permits us to count other
types of structures in circulant graphs, e.g., Hamiltonian Cycles.


title:
Periodic-orbit determination of dynamical correlations in stochastic
  processes

abstract:
  It is shown that large deviation statistical quantities of the discrete time,
finite state Markov process $P_{n+1}^{(j)}=\sum_{k=1}^NH_{jk}P_n^{(k)}$, where
P_n^{(j)} is the probability for the j-state at the time step n and H_{jk} is
the transition probability, completely coincides with those from the Kalman map
corresponding to the above Markov process. Furthermore, it is demonstrated that
by using simple examples, time correlation functions in finite state Markov
processes can be well described in terms of unstable periodic orbits embedded
in the equivalent Kalman maps.


title: On the Self-stabilization of Mobile Robots in Graphs

abstract:
  Self-stabilization is a versatile technique to withstand any transient fault
in a distributed system. Mobile robots (or agents) are one of the emerging
trends in distributed computing as they mimic autonomous biologic entities. The
contribution of this paper is threefold. First, we present a new model for
studying mobile entities in networks subject to transient faults. Our model
differs from the classical robot model because robots have constraints about
the paths they are allowed to follow, and from the classical agent model
because the number of agents remains fixed throughout the execution of the
protocol. Second, in this model, we study the possibility of designing
self-stabilizing algorithms when those algorithms are run by mobile robots (or
agents) evolving on a graph. We concentrate on the core building blocks of
robot and agents problems: naming and leader election. Not surprisingly, when
no constraints are given on the network graph topology and local execution
model, both problems are impossible to solve. Finally, using minimal hypothesis
with respect to impossibility results, we provide deterministic and
probabilistic solutions to both problems, and show equivalence of these
problems by an algorithmic reduction mechanism.


title: Charge-Ordered State versus Dimer-Mott Insulator at Finite Temperatures

abstract:
  We theoretically investigate the competition between charge-ordered state and
Mott insulating state at finite temperatures in quarter-filled
quasi-one-dimensional electron systems, by studying dimerized extended Hubbard
chains with interchain Coulomb interactions. In order to take into account
one-dimensional fluctuations properly, we apply the bosonization method to an
effective model obtained by the interchain mean-field approximation. The
results show that lattice dimerization, especially in the critical region, and
frustration in the interchain Coulomb interactions reduce the charge-ordering
phase transition temperature and enlarge the dimer-Mott insulating phase. We
also derive a general formula of the Knight shift in the charge-ordered phase
and its implication to experiments is discussed.


title: Extra Dimensions and the Cosmological Constant Problem

abstract:
  This article reviews the arguments why extra dimensions provide a unique
opportunity for progress on the cosmological constant problem, and updates the
status of -- and the objections to (with replies) -- the specific proposal
using supersymmetric large extra dimensions (SLED).


title: Evidence for dust accumulation just outside the orbit of Venus

abstract:
  To contribute to the knowledge of dynamics of interplanetary dust we are
searching for structures in the spatial distribution of interplanetary dust
near the orbit of Venus. To this end we study the radial gradient of zodiacal
light brightness, as observed by the zodiacal light photometer on board the
Helios space probes on several orbits from 1975 to 1979. The cleanest data
result from Helios B (= Helios 2) launched in January 1976. With respect to the
general increase of zodiacal light brightness towards the Sun, the data show an
excess brightness of a few percent for positions of the Helios space probe just
outside the orbit of Venus. We consider this as evidence for a dust ring
associated with the orbit of Venus, somewhat similar to that found earlier
along the Earth's orbit.


title:
An explicit estimate on multiplicity truncation in the second main
  theorem for holomorphic curves encountering hypersurfaces in general position
  in projective space

abstract:
  Yan and Chen proved a weak Cartan-type second main theorem for holomorphic
curves meeting hypersurfaces in projective space that included truncated
counting functions. Here we give an explicit estimate for the level of
truncation.


title:
Transverse Energy per Charged Particle and Freeze-Out Criteria in
  Heavy-Ion Collisions

abstract:
  In relativistic nucleus-nucleus collisions the transverse energy per charged
particle, E_T/N_ch, increases rapidly with beam energy and remains
approximately constant at about 800 MeV for beam energies from SPS to RHIC. It
is shown that the hadron resonance gas model describes the energy dependence,
as well as the lack of centrality dependence, qualitatively. The values of
E_T/N_ch are related to the chemical freeze-out criterium E/N about 1 GeV valid
for primordial hadrons.


title: Two particles on a star graph I

abstract:
  We consider a two particle system on a star graph with $\delta$-function
interaction. A class of eigensolutions is described which are constructed from
appropriate one particle solutions, and hence are parametrised by two momenta.
These solutions include a family of solutions with discontinuous derivative on
the diagonal.


title: Higgs Decay to Gluons at NNLO

abstract:
  We present an analytical calculation of the next-to-next-to-leading order
corrections to the partial decay width $H\to gg$ for a Higgs boson in the
intermediate mass range. We apply an asymptotic expansion for $M_H\ll 2M_t$ and
compute three terms in the expansion. The leading term confirms the results
present in the literature. It is argued that our result is equivalent to an
exact calculation up to $M_H\approx M_t$. For a Higgs boson mass of 120 GeV the
power-suppressed terms lead to corrections of about 9% in the
next-to-next-to-leading order coefficient.


title: Test of pulse shape analysis using single Compton scattering events

abstract:
  Compton scattering is one of the dominant interaction processes in germanium
for photons with an energy of around two MeV. If a photon scatters only once
inside a germanium detector, the resulting event contains only one electron
which normally deposits its energy within a mm range. Such events are similar
to Ge-76 neutrinoless double beta-decay events with just two electrons in the
final state. Other photon interactions like pair production or multiple
scattering can result in events composed of separated energy deposits. One
method to identify the multiple energy deposits is the use of timing
information contained in the electrical response of a detector or a segment of
a detector.
  The procedures developed to separate single- and multiple-site events are
tested with specially selected event samples provided by an 18-fold segmented
prototype germanium detector for Phase II of the GERmanium Detector Array,
GERDA. The single Compton scattering, i.e. single-site, events are tagged by
coincidently detecting the scattered photon with a second detector positioned
at a defined angle. A neural network is trained to separate such events from
events which come from multi-site dominated samples. Identification
efficiencies of ~80% are achieved for both single- and multi-site events.


title: A spherical model with directional interactions: I. Static properties

abstract:
  We introduce a simple spherical model whose structural properties are similar
to the ones generated by models with directional interactions, by employing a
binary mixture of large and small hard spheres, with a square-well attraction
acting only between particles of different size. The small particles provide
the bonds between the large ones. With a proper choice of the interaction
parameters, as well as of the relative concentration of the two species, it is
possible to control the effective valence. Here we focus on a specific choice
of the parameters which favors tetrahedral ordering and study the equilibrium
static properties of the system in a large window of densities and
temperatures. Upon lowering the temperature we observe a progressive increase
in local order, accompanied by the formation of a four-coordinated network of
bonds. Three different density regions are observed: at low density the system
phase separates into a gas and a liquid phase; at intermediate densities a
network of fully bonded particles develops; at high densities -- due to the
competition between excluded volume and attractive interactions -- the system
forms a defective network. The very same behavior has been previously observed
in numerical studies of non-spherical models for molecular liquids, such as
water, and in models of patchy colloidal particles. Differently from these
models, theoretical treatments devised for spherical potentials, e.g. integral
equations and ideal mode coupling theory for the glass transition can be
applied in the present case, opening the way for a deeper understanding of the
thermodynamic and dynamic behavior of low valence molecules and particles.


title: On the superfluidity of classical liquid in nanotubes

abstract:
  In 2001, the author proposed the ultra second quantization method. The ultra
second quantization of the Schr\"odinger equation, as well as its ordinary
second quantization, is a representation of the N-particle Schr\"odinger
equation, and this means that basically the ultra second quantization of the
equation is the same as the original N-particle equation: they coincide in
3N-dimensional space.
  We consider a short action pairwise potential V(x_i -x_j). This means that as
the number of particles tends to infinity, $N\to\infty$, interaction is
possible for only a finite number of particles. Therefore, the potential
depends on N in the following way: $V_N=V((x_i-x_j)N^{1/3})$. If V(y) is finite
with support $\Omega_V$, then as $N\to\infty$ the support engulfs a finite
number of particles, and this number does not depend on N.
  As a result, it turns out that the superfluidity occurs for velocities less
than $\min(\lambda_{\text{crit}}, \frac{h}{2mR})$, where
$\lambda_{\text{crit}}$ is the critical Landau velocity and R is the radius of
the nanotube.


title: Planar graphs and covers

abstract:
  Planar locally finite graphs which are almost vertex transitive are
discussed. If the graph is 3-connected and has at most one end then the group
of automorphisms is a planar discontinuous group and its structure is
well-known. A general result is obtained for such graphs where no restriction
is put on the number of ends. It is shown that such a graph can be built up
from one ended or finite planar graphs in a precise way. The results give a
classification of the finitely generated groups with planar Cayley graphs.


title:
Evidence for gap anisotropy in CaC6 from directional point-contact
  spectroscopy

abstract:
  We present the first results of directional point-contact spectroscopy in
high quality CaC6 samples both along the ab plane and in the c-axis direction.
The superconducting order parameter \Delta(0), obtained by fitting the
Andreev-reflection (AR) conductance curves at temperatures down to 400 mK with
the single-band 3D Blonder-Tinkham-Klapwijk model, presents two different
distributions in the two directions of the main current injection, peaked at
1.35 and 1.71 meV, respectively. By ab-initio calculations of the AR
conductance spectra, we show that the experimental results are in good
agreement with the recent predictions of gap anisotropy in CaC6.


title:
Star Formation in NGC 5194 (M51a). II. The Spatially-Resolved Star
  Formation Law

abstract:
  We have studied the relationship between the star formation rate (SFR)
surface density and gas surface density in the spiral galaxy M51a (NGC 5194),
using multi-wavelength data obtained as part of the Spitzer Infrared Nearby
Galaxies Survey (SINGS). We introduce a new SFR index based on a linear
combination of H-alpha emission-line and 24 micron continuum luminosities, that
provides reliable extinction-corrected ionizing fluxes and SFR densities over a
wide range of dust attenuations. The combination of these extinction-corrected
SFR densities with aperture synthesis HI and CO maps has allowed us to probe
the form of the spatially-resolved star formation law on scales of 0.5 to 2
kpc. We find that the resolved SFR vs gas surface density relation is well
represented by a Schmidt power law, which is similar in form and dispersion to
the disk-averaged Schmidt law. We observe a comparably strong correlation of
the SFR surface density with the molecular gas surface density, but no
significant correlation with the surface density of atomic gas. The
best-fitting slope of the Schmidt law varies from N = 1.37 to 1.56, with
zeropoint and slope that change systematically with the spatial sampling scale.
We tentatively attribute these variations to the effects of areal sampling and
averaging of a nonlinear intrinsic star formation law. Our data can also be
fitted by an alternative parametrization of the SFR surface density in terms of
the ratio of gas surface density to local dynamical time, but with a
considerable dispersion.


title: Spherical Nilpotent Orbits in Positive Characteristic

abstract:
  Let G be a connected reductive linear algebraic group defined over an
algebraically closed field of characteristic p. Assume that p is good for G. In
this note we classify all the spherical nilpotent G-orbits in the Lie algebra
of G. The classification is the same as in the characteristic zero case
obtained by D.I. Panyushev in 1994: for e a nilpotent element in the Lie
algebra of G, the G-orbit G.e is spherical if and only if the height of e is at
most 3.


title:
Modified non-local-F(R) gravity as the key for the inflation and dark
  energy

abstract:
  We consider FRW cosmology in non-local modified gravity. Its local
scalar-tensor formulation is developed. It is explicitly demonstrated that such
theory may lead to the unification of early-time inflation with late-time
cosmic acceleration. The quintessence or phantom era may emerge for specific
form of the action. The coupled non-local-F(R) gravity is also investigated. It
is shown that such theory being consistent with Solar System tests may lead to
the known universe history sequence: inflation, radiation/matter dominance and
dark epoch.


title: Emergence of communities in weighted networks

abstract:
  Topology and weights are closely related in weighted complex networks and
this is reflected in their modular structure. We present a simple network model
where the weights are generated dynamically and they shape the developing
topology. By tuning a model parameter governing the importance of weights, the
resulting networks undergo a gradual structural transition from a module free
topology to one with communities. The model also reproduces many features of
large social networks, including the "weak links" property.


title: Dynamical Lower Bounds for 1D Dirac Operators

abstract:
  Quantum dynamical lower bounds for continuous and discrete one-dimensional
Dirac operators are established in terms of transfer matrices. Then such
results are applied to various models, including the Bernoulli-Dirac one and,
in contrast to the discrete case, critical energies are also found for the
continuous Dirac case with positive mass.


title:
Modeling Visual Information Processing in Brain: A Computer Vision Point
  of View and Approach

abstract:
  We live in the Information Age, and information has become a critically
important component of our life. The success of the Internet made huge amounts
of it easily available and accessible to everyone. To keep the flow of this
information manageable, means for its faultless circulation and effective
handling have become urgently required. Considerable research efforts are
dedicated today to address this necessity, but they are seriously hampered by
the lack of a common agreement about "What is information?" In particular, what
is "visual information" - human's primary input from the surrounding world. The
problem is further aggravated by a long-lasting stance borrowed from the
biological vision research that assumes human-like information processing as an
enigmatic mix of perceptual and cognitive vision faculties. I am trying to find
a remedy for this bizarre situation. Relying on a new definition of
"information", which can be derived from Kolmogorov's compexity theory and
Chaitin's notion of algorithmic information, I propose a unifying framework for
visual information processing, which explicitly accounts for the perceptual and
cognitive image processing peculiarities. I believe that this framework will be
useful to overcome the difficulties that are impeding our attempts to develop
the right model of human-like intelligent image processing.


title:
Dual Bosonic Thermal Green Function and Fermion Correlators of the
  Massive Thirring Model at a Finite Temperature

abstract:
  The Euclidian thermal Green function of the two-dimensional (2D) free
massless scalar field in coordinate space is written as the real part of a
complex analytic function of a variable that conformally maps the infinite
strip $-\infty<x<\infty$ ($0<\tau<\beta$) of the $z=x+i\tau$ ($\tau$: imaginary
time) plane into the upper-half-plane. Using this fact and the Cauchy-Riemann
conditions, we identify the dual thermal Green function as the imaginary part
of that function. Using both the thermal Green function and its dual, we obtain
an explicit series expression for the fermionic correlation functions of the
massive Thirring model (MTM) at a finite temperature.


title: Relativity without tears

abstract:
  Special relativity is no longer a new revolutionary theory but a firmly
established cornerstone of modern physics. The teaching of special relativity,
however, still follows its presentation as it unfolded historically, trying to
convince the audience of this teaching that Newtonian physics is natural but
incorrect and special relativity is its paradoxical but correct amendment. I
argue in this article in favor of logical instead of historical trend in
teaching of relativity and that special relativity is neither paradoxical nor
correct (in the absolute sense of the nineteenth century) but the most natural
and expected description of the real space-time around us valid for all
practical purposes. This last circumstance constitutes a profound mystery of
modern physics better known as the cosmological constant problem.


title: Violation of Porod law in a freely cooling granular gas in one dimension

abstract:
  We study a model of freely cooling inelastic granular gas in one dimension,
with a restitution coefficient which approaches the elastic limit below a
relative velocity scale v. While at early times (t << 1/v) the gas behaves as a
completely inelastic sticky gas conforming to predictions of earlier studies,
at late times (t >> 1/v) it exhibits a new fluctuation dominated phase ordering
state. We find distinct scaling behavior for the (i) density distribution
function, (ii) occupied and empty gap distribution functions, (iii) the density
structure function and (iv) the velocity structure function, as compared to the
completely inelastic sticky gas. The spatial structure functions (iii) and (iv)
violate the Porod law. Within a mean-field approximation, the exponents
describing the structure functions are related to those describing the spatial
gap distribution functions.


title:
Spectroscopy of the a^3\Sigma_u^+ state and the coupling to the
  X^1\Sigma_g^+ state of K_2

abstract:
  We report on high resolution Fourier-transform spectroscopy of fluorescence
to the a^3\Sigma_u^+ state excited by two-photon or two-step excitation from
the X^1\Sigma_g^+ state to the 2^3\Pi_g state in the molecule K_2. These
spectroscopic data are combined with recent results of Feshbach resonances and
two-color photoassociation spectra for deriving the potential curves of
X^1\Sigma_g^+ and a^3\Sigma_u^+ up to the asymptote. The precise relative
position of the triplet levels with respect of the singlet levels was achieved
by including the excitation energies from the X^1\Sigma_g^+ state to the
2^3\Pi_g state and down to the a^3\Sigma_u^+ state in the simultaneous fit of
both potentials. The derived precise potential curves allow for reliable
modeling of cold collisions of pairs of potassium atoms in their ^2S ground
state.


title:
Inflating Fat Bubbles in Clusters of Galaxies by Precessing Massive Slow
  Jets

abstract:
  We conduct hydrodynamical numerical simulations and find that precessing
massive slow jets can inflate fat bubbles, i.e., more or less spherical
bubbles, that are attached to the center of clusters of galaxies. To inflate a
fat bubble the jet should precess fast. The precessing angle $\theta$ should be
large, or change over a large range $ 0 \le \theta \le \theta_{\max} \sim 30-70
^\circ$ (depending also on other parameters), where $\theta=0$ is the symmetry
axis. The constraints on the velocity and mass outflow rate are similar to
those on wide jets to inflate fat bubbles. The velocity should be $v_j \sim
10^4 \kms$, and the mass loss rate of the two jets should be $ 2 \dot M_j
\simeq 1-50 \dot M_\odot \yr^{-1} $. These results, and our results from a
previous paper dealing with slow wide jets, support the claim that a large
fraction of the feedback heating in cooling flow clusters and in the processes
of galaxy formation is done by slow massive jets.


title: How not to discard half of the cases in QKD

abstract:
  All known QKD protocols require the parties to discard the results when they
have chosen differen bases. In this paper we show that it is not necessary. We
give examples of QKD protocols that are as safe as standard ones but do not
involve the discarding the results when the bases are different or even that do
not require the announcement of the bases. This leads to greater communication
channel capacities and render some eavesdropping strategies useless but the
most important thing is that they provide us better insight into the general
structures that underlie the quantum cryptography and help to establish the
boundaries of what is possible and what is not.


title: Generalized Cherednik-Macdonald identities

abstract:
  We derive generalizations of the Cherednik-Macdonald constant term identities
associated to root systems which depend, besides on the usual multiplicity
function, symmetrically on two quasi-periods. They are natural analogues of the
Cherednik-Macdonald constant term q-identities in which the deformation
parameter q is allowed to have modulus one. They unite the Cherednik-Macdonald
constant term q-identities with closely related Jackson p-integral identities
due to Macdonald, where the deformation parameter p is related to q by modular
inversion.


title: Thermodynamical quantities for overlap fermions with chemical potential

abstract:
  Recently a formulation of overlap fermions at finite density based on an
analytic continuation of the sign function was proposed. We study this proposal
by analyzing the energy and number densities for free fermions as a function of
the chemical potential and the temperature. Our results show that overlap
fermions with chemical potential give rise to the correct continuum behavior.


title:
Couplings of the Rho Meson in a Holographic dual of QCD with Regge
  Trajectories

abstract:
  The couplings $g_{\rho HH}$ of the $\rho$ meson with any hadron H are
calculated in a holographic dual of QCD where the Regge trajectories for mesons
are manifest. The resulting couplings grow linearly with the exciting number of
H, thus are far from universal. A simple argument has been given for this
behavior based on quasi-classical picture of excited hadrons. It seems that in
holographic duals with exact Regge trajectories the $g_{\rho HH}$ universality
should be violated. The $\rho$-dominance for the electromagnetic form factors
of H are also strongly violated, except for the lowest state, the pion. Quite
unexpected, the form factor of the pion is completely saturated by the
contribution of the $\rho$. The asymptotic behavior of the form factors are
also calculated, and are found to be perfectly accordant with the prediction of
conformal symmetry and pertubative QCD.


title: U-boson and the HyperCP exotic events

abstract:
  We show that the very light spin-1 gauge U-boson of the extra $U(1)'$ gauge
model in the framework of the supersymmetric standard model extension can be a
good candidate of the new light particle suggested by the HyperCP experiment.
We demonstrate that the flavor changing neutral currents (FCNCs) for the
HyperCP events in the decay of $\Sigma^{+}\to p \mu^{+} \mu^{-}$ can be
generated at both tree and loop levels. In particular, we find that the loop
induced $s\to d U$ transition due to the tensor-type interaction with the
dimension-5 electric dipole operator plays a very important role on the FCNCs.
Our explanation of the HyperCP data with the spin-1 U-boson is different from
that based on a light pseudoscalar Higgs boson or sgoldstino in the literature.
In particular, the U-boson involves a rich phenomenology in particle physics as
well as cosmology.


title:
Cavity cooling of translational and ro-vibrational motion of molecules:
  ab initio-based simulations for OH and NO

abstract:
  We present detailed calculations at the basis of our recent proposal for
simultaneous cooling the rotational, vibrational and external molecular degrees
of freedom. In this method, the molecular rovibronic states are coupled by an
intense laser and an optical cavity via coherent Raman processes enhanced by
the strong coupling with the cavity modes. For a prototype system, OH, we
showed that the translational motion is cooled to few micro Kelvin and the
molecule is brought to the internal ground state in about a second. Here, we
investigate numerically the dependence of the cooling scheme on the molecular
polarizability, selecting NO as a second example. Furthermore, we demonstrate
the general applicability of the proposed cooling scheme to initially
vibrationally and rotationally hot molecular systems.


title:
Spin and charge orders and their hole-doping dependence in single
  layered cobaltate La2-xCaxCoO4(0.3<x<0.8)

abstract:
  Neutron scattering experiments were performed on single crystals of layered
cobalt-oxides La2-xCaxCoO4 (LCCO) to characterize the charge and spin orders in
a wide hole-doping range of 0.3<x<0.8. For a commensurate value of x=0.5 in
(H,0,L) plane, two types of superlattice reflections concomitantly appear at
low temperature; one corresponds to a checkerboard charge ordered pattern of
Co2+/Co3+ ions and the other is magnetic in origin. Further, the latter
magnetic-superlattice peaks show two types of symmetry in the reflections,
suggesting antiferromagnetic-stacking (AF-S) and ferromagnetic-stacking (F-S)
patterns of spins along the c direction. From the hole-doping dependence, the
in-plane correlation lengths of both charge and spin orders are found to give a
maximum at x=0.5. These features are the same with those of x=0.5 in
La1-xSr1+xMnO4 (LSMO), a typical checkerboard and spin ordered compound.
However, in (H,H,L) plane, we found a magnetic scattering peak at
Q=(1/4,1/4,1/2) position below TN. This magnetic peak can not be understood by
considering the Co2+ spin configuration, suggesting that this peak is
originated from Co3+ spin order. By analyzing these superlattice reflections,
we found that they are originated from high-spin state of Co3+ spin order.


title: Charged-Higgs Collider Signals with or without Flavor

abstract:
  A charged Higgs boson is a clear signal for an extended Higgs sector, as for
example predicted by supersymmetry. Squark mixing can significantly change the
pattern of charged-Higgs production and most notably circumvent the chiral
suppression for single Higgs production. We evaluate the LHC discovery
potential in the light of flavor physics, in the single-Higgs production
channel and in association with a hard jet for small and moderate values of tan
beta. Thoroughly examining current flavor constraints we find that non-minimal
flavor structures can have a sizeable impact, but tend to predict moderate
production rates. Nevertheless, charged-Higgs searches will probe flavor
structures not accessible to rare kaon, bottom, or charm experiments, and can
invalidate the assumption of minimal flavor violation.


title: An entire function with simply and multiply connected wandering domains

abstract:
  We modify a construction of Kisaka and Shishikura to show that there exists
an entire function which has both a simply connected and a multiply connected
wandering domain. Moreover, these domains are contained in the set of fast
escaping points.


title: Evolution of supermassive black holes

abstract:
  The cosmological evolution of supermassive black holes (SMBHs) seems to be
intimately linked to their host galaxies. Active galactic nuclei (AGN) can be
probed by deep X-ray surveys. We review results from large X-ray selected
samples including first results from the XMM-Newton COSMOS survey. A new
picture arises from the fact that high-luminosity AGN grow earlier than
low-luminosity AGN. In particular, the space density of low-luminosity AGN
exhibits a significant decline for redshifts above z=1. This
'anti--hierarchical' growth scenario of SMBHs can be explained by two modes of
accretion with different efficiency. The population of Compton-thick sources
plays a key role in our understanding of the BH growth history. Their space
density and redshift distribution is relevant to estimate the SMBH mass
function. A comparison with the relic SMBH mass distribution in the local
Universe constrains the average radiative efficiency and Eddington ratio of the
accretion. We discuss a new synthesis model of Compton-thin and Compton-thick
sources that is in concordance with deep X-ray observations and in particular
predicts the right level of contribution of the Compton-thick source population
observed in the Chandra Deep Field South observations as well as the first
INTEGRAL and Swift catalogues of AGN. Currently, one of the most important
problems is the evolution of obscuration with redshift.


title: Kinematics of the Scorpius-Centaurus OB Association

abstract:
  A fine structure related to the kinematic peculiarities of three components
of the Scorpius-Centaurus association (LCC, UCL, and US) has been revealed in
the UV-velocity distribution of Gould Belt stars. We have been able to identify
the most likely members of these groups by applying the method of analyzing the
two-dimensional probability density function of stellar UV velocities that we
developed. A kinematic analysis of the identified structural components has
shown that, in general, the center--of--mass motion of the LCC, UCL, and US
groups follows the motion characteristic of the Gould Belt, notably its
expansion. The entire Scorpius-Centaurus complex is shown to possess a proper
expansion with an angular velocity parameter of 46+-8 km/s/kpc for the
kinematic center with lo=-40 degrees and Ro=110 pc found. Based on this
velocity, we have estimated the characteristic expansion time of the complex to
be 21+-4 Myr. The proper rotation velocity of the Scorpius-Centaurus complex is
lower in magnitude, is determined less reliably, and depends markedly on the
data quality.


title:
Highly efficient single photon emission from single quantum dots within
  a two-dimensional photonic bandgap

abstract:
  We report highly efficient single photon generation from InGaAs
self-assembled quantum dots emitting within a two-dimensional photonic bandgap.
A strongly suppressed multiphoton probability is obtained for single quantum
dots in bulk GaAs and those emitting into the photonic bandgap. In the latter
case, photoluminescence saturation spectroscopy is employed to measure a ~17
times enhancement of the average photon extraction efficiency, when compared to
quantum dots in bulk GaAs. For quantum dots in the photonic crystal we measure
directly an external quantum efficiency up to 26%, much higher than for quantum
dots on the same sample without a tailored photonic environment. The results
show that highly efficient quantum dot single photon sources can be realized,
without the need for complex nanopositioning techniques.


title: An iterative tomogravity algorithm for the estimation of network traffic

abstract:
  This paper introduces an iterative tomogravity algorithm for the estimation
of a network traffic matrix based on one snapshot observation of the link loads
in the network. The proposed method does not require complete observation of
the total load on individual edge links or proper tuning of a penalty parameter
as existing methods do. Numerical results are presented to demonstrate that the
iterative tomogravity method controls the estimation error well when the link
data is fully observed and produces robust results with moderate amount of
missing link data.


title:
Asymptotics for Hermite-Pade rational approximants for two analytic
  functions with separated pairs of branch points (case of genus 0)

abstract:
  We investigate the asymptotic behavior for type II Hermite-Pade approximation
to two functions, where each function has two branch points and the pairs of
branch points are separated. We give a classification of the cases such that
the limiting counting measures for the poles of the Hermite-Pade approximants
are described by an algebraic function of order 3 and genus 0. This situation
gives rise to a vector-potential equilibrium problem for three measures and the
poles of the common denominator are asymptotically distributed like one of
these measures. We also work out the strong asymptotics for the corresponding
Hermite-Pade approximants by using a 3x3 Riemann-Hilbert problem that
characterizes this Hermite-Pade approximation problem.


title: Rational semigroup automata

abstract:
  We show that for any monoid M, the family of languages accepted by M-automata
(or equivalently, generated by regular valence grammars over M) is completely
determined by that part of M which lies outside the maximal ideal. Hence, every
such family arises as the family of languages accepted by N-automata where N is
a simple or 0-simple monoid. A consequence is that every such family is either
the class of regular languages, contains all the blind one-counter languages,
or is the family of languages accepted by G-automata for G a non-locally-finite
torsion group.
  We consider a natural extension of the usual definition which permits the
automata to utilise more of the structure of each monoid, and also allows us to
define S-automata for S an arbitrary semigroup. In the monoid case, the
resulting automata are equivalent to the valence automata with rational target
sets} which arise in the theory of regulated rewriting systems. We study the
case that the register semigroup is completely simple or completely 0-simple,
obtaining a complete characterisation of the classes of languages corresponding
to such semigroups in terms of their maximal subgroups. In the process, we
obtain a number of results about rational subsets of Rees matrix semigroups
which may be of independent interest.


title:
Pricing, Hedging and Optimally Designing Derivatives Via Minimization of
  Risk Measures

abstract:
  The question of pricing and hedging a given contingent claim has a unique
solution in a complete market framework. When some incompleteness is
introduced, the problem becomes however more difficult. Several approaches have
been adopted in the literature to provide a satisfactory answer to this
problem, for a particular choice criterion. In this paper, in order to price
and hedge a non-tradable contingent claim, we first start with a (standard)
utility maximization problem and end up with an equivalent risk measure
minimization. This hedging problem can be seen as a particular case of a more
general situation of risk transfer between different agents, one of them
consisting of the financial market. In order to provide constructive answers to
this general optimal risk transfer problem, both static and dynamic approaches
are considered. When considering a dynamic framework, our main purpose is to
find a trade-off between static and very abstract risk measures as we are more
interested in tractability issues and interpretations of the dynamic risk
measures we obtain rather than the ultimate general results. Therefore, after
introducing a general axiomatic approach to dynamic risk measures, we relate
the dynamic version of convex risk measures to BSDEs.


title: The Evolution of Galaxies

abstract:
  The evolution of galaxies results from a combination of internal and external
processes. The star formation is an internal process transforming cold and
dense cores of molecular clouds to stars. It may be triggered internally by
expanding shells, or externally, e. g. by galaxy collisions. The gas accretion
and galaxy merging events are external contributors to galaxy evolution. They
compete with another internal process of galaxy evolution, which is the secular
evolution redistributing the mass and angular momentum inside of galaxies as a
consequence of bar and spiral arms formation. As a nearby example of gas
accretion we mention the interacting system Milky Way - Large and Small
Magellanic Clouds. Stripping of ISM in galaxy clusters is reviewed as another
example of interaction of galaxies with their environment.


title:
Characteristic Energy of the Coulomb Interactions and the Pileup of
  States

abstract:
  Tunneling data on $\mathrm{La_{1.28}Sr_{1.72}Mn_2O_7}$ crystals confirm
Coulomb interaction effects through the $\sqrt{\mathrm{E}}$ dependence of the
density of states. Importantly, the data and analysis at high energy, E, show a
pileup of states: most of the states removed from near the Fermi level are
found between ~40 and 130 meV, from which we infer the possibility of universal
behavior. The agreement of our tunneling data with recent photoemission results
further confirms our analysis.


title:
Smooth matter and source size in microlensing simulations of
  gravitationally lensed quasars

abstract:
  Several gravitationally lensed quasars are observed with anomalous
magnifications in pairs of images that straddle a critical curve. Simple
theoretical arguments suggest that the magnification of these images should be
approximately equivalent, whereas one image is observed to be significantly
demagnified. Microlensing provides a possible explanation for this discrepancy.
There are two key parameters when modelling this effect. The first, the
fraction of smooth matter in the lens at the image positions, has been explored
by Schechter and Wambsganss (2002). They have shown that the anomalous flux
ratio observed in the lensed quasar MG 0414+0534 is a priori a factor of 5 more
likely if the assumed smooth matter content in the lens model is increased from
0% to 93%. The second parameter, the size of the emission region, is explored
in this paper, and shown to be more significant. We find that the broadening of
the magnification probability distributions due to smooth matter content is
washed out for source sizes that are predicted by standard models for quasars.
We apply our model to the anomalous lensed quasar MG 0414+0534, and find a 95%
upper limit of 2.62 x 10^(16) h^(-1/2) (M/Msun)^(1/2) cm on the radius of the
I-band emission region. The smooth matter percentage in the lens is
unconstrained.


title: Law of Large Numbers Limits for Many Server Queues

abstract:
  This work considers a many-server queueing system in which customers with
i.i.d., generally distributed service times enter service in the order of
arrival. The dynamics of the system is represented in terms of a process that
describes the total number of customers in the system, as well as a
measure-valued process that keeps track of the ages of customers in service.
Under mild assumptions on the service time distribution, as the number of
servers goes to infinity, a law of large numbers (or fluid) limit is
established for this pair of processes. The limit is characterised as the
unique solution to a coupled pair of integral equations, which admits a fairly
explicit representation. As a corollary, the fluid limits of several other
functionals of interest, such as the waiting time, are also obtained.
Furthermore, in the time-homogeneous setting, the fluid limit is shown to
converge to its equilibrium. Along the way, some results of independent
interest are obtained, including a continuous mapping result and a maximality
property of the fluid limit. A motivation for studying these systems is that
they arise as models of computer data systems and call centers.


title:
Chandra View of DA 530: A Sub-Energetic Supernova Remnant with a Pulsar
  Wind Nebula?

abstract:
  Based on a Chandra ACIS observation, we report the detection of an extended
X-ray feature close to the center of the remnant DA 530 with 5.3 sigma above
the background within a circle of 20'' radius. This feature, characterized by a
power-law with the photon index gamma=1.6+-0.8 and spatially coinciding with a
nonthermal radiosource, most likely represents a pulsar wind nebula. We have
further examined the spectrum of the diffuse X-ray emission from the remnant
interior with a background-subtracted count rate of ~0.06 counts s^-1 in
0.3-3.5 keV. The spectrum of the emission can be described by a thermal plasma
with a temperature of ~0.3-0.6 keV and a Si over-abundance of >~7 solar. These
spectral characteristics, together with the extremely low X-ray luminosity,
suggest that the remnant arises from a supernova with an anomalously low
mechanical energy (<10^50 ergs). The centrally-filled thermal X-ray emission of
the remnant may indicate an early thermalization of the SN ejecta by the
circum-stellar medium. Our results suggest that the remnant is likely the
product of a core-collapsed SN with a progenitor mass of 8-12 Msun. Similar
remnants are probably common in the Galaxy, but have rarely been studied.


title:
The HARPS search for southern extra-solar planets XII. A giant planet
  orbiting the metal-poor star HD171028

abstract:
  In this paper we present the detection of a 1.8 M_Jup planet in a 538 day
period trajectory orbiting the metal-poor star HD171028 ([Fe/H]=-0.49). This
planet is the first to be discovered in the context of a HARPS program
searching for planets around metal-poor stars. Interestingly, HD171028 is one
of the least metal-poor stars in the sample. This discovery is placed in the
context of the models of planet formation and evolution.


title: Formal Maurer-Cartan Structures: from CFT to Classical Field Equations

abstract:
  We show how the well-known classical field equations as Einstein and
Yang-Mills ones, which arise as the conformal invariance conditions of certain
two-dimensional theories, expanded up to the second order in the formal
parameter, can be reformulated as Generalized/formal Maurer-Cartan equations
(GMC), where the differential is the BRST operator of String theory. We
introduce the bilinear operations which are present in GMC, and study their
properties, allowing us to find the symmetries of the resulting equations which
will be naturally identified with the diffeomorphism and gauge symmetries of
Einstein and Yang-Mills equations correspondingly.


title: Quantum estimation via minimum Kullback entropy principle

abstract:
  We address quantum estimation in situations where one has at disposal data
from the measurement of an incomplete set of observables and some a priori
information on the state itself. By expressing the a priori information in
terms of a bias toward a given state the problem may be faced by minimizing the
quantum relative entropy (Kullback entropy) with the constraint of reproducing
the data. We exploit the resulting minimum Kullback entropy principle for the
estimation of a quantum state from the measurement of a single observable,
either from the sole mean value or from the complete probability distribution,
and apply it as a tool for the estimation of weak Hamiltonian processes. Qubit
and harmonic oscillator systems are analyzed in some details.


title: Stanilov-Tsankov-Videv Theory

abstract:
  We survey some recent results concerning Stanilov-Tsankov-Videv theory,
conformal Osserman geometry, and Walker geometry which relate algebraic
properties of the curvature operator to the underlying geometry of the
manifold.


title: Role models for complex networks

abstract:
  We present a framework for automatically decomposing ("block-modeling") the
functional classes of agents within a complex network. These classes are
represented by the nodes of an image graph ("block model") depicting the main
patterns of connectivity and thus functional roles in the network. Using a
first principles approach, we derive a measure for the fit of a network to any
given image graph allowing objective hypothesis testing. From the properties of
an optimal fit, we derive how to find the best fitting image graph directly
from the network and present a criterion to avoid overfitting. The method can
handle both two-mode and one-mode data, directed and undirected as well as
weighted networks and allows for different types of links to be dealt with
simultaneously. It is non-parametric and computationally efficient. The
concepts of structural equivalence and modularity are found as special cases of
our approach. We apply our method to the world trade network and analyze the
roles individual countries play in the global economy.


title:
A flexible Bayesian generalized linear model for dichotomous response
  data with an application to text categorization

abstract:
  We present a class of sparse generalized linear models that include probit
and logistic regression as special cases and offer some extra flexibility. We
provide an EM algorithm for learning the parameters of these models from data.
We apply our method in text classification and in simulated data and show that
our method outperforms the logistic and probit models and also the elastic net,
in general by a substantial margin.


title:
Experimental Demonstration of Decoherence-Free One-Way Information
  Transfer

abstract:
  We report the experimental demonstration of a one-way quantum protocol
reliably operating in the presence of decoherence. Information is protected by
designing an appropriate decoherence-free subspace for a cluster state
resource. We demonstrate our scheme in an all-optical setup, encoding the
information into the polarization states of four photons. A measurement-based
one-way information-transfer protocol is performed with the photons exposed to
severe symmetric phase-damping noise. Remarkable protection of information is
accomplished, delivering nearly ideal outcomes.


title: Visualization of Cosmological Particle-Based Datasets

abstract:
  We describe our visualization process for a particle-based simulation of the
formation of the first stars and their impact on cosmic history. The dataset
consists of several hundred time-steps of point simulation data, with each
time-step containing approximately two million point particles. For each
time-step, we interpolate the point data onto a regular grid using a method
taken from the radiance estimate of photon mapping. We import the resulting
regular grid representation into ParaView, with which we extract isosurfaces
across multiple variables. Our images provide insights into the evolution of
the early universe, tracing the cosmic transition from an initially homogeneous
state to one of increasing complexity. Specifically, our visualizations capture
the build-up of regions of ionized gas around the first stars, their evolution,
and their complex interactions with the surrounding matter. These observations
will guide the upcoming James Webb Space Telescope, the key astronomy mission
of the next decade.


title: Overconvergence and classicality: the case of curves

abstract:
  Given our set-up of a system of curves and maps between them satisfying
certain assumptions, we prove a classicality criterion for overconvergent
sections of line bundles over these curves. As a result, we prove such criteria
for overconvergent modular forms over various Shimura curves. In particular, we
provide a classicality criterion for overconvergent modular forms studied in
[Kassaei: P-adic modular forms over Shimura curves over totally real fields,
Compositio Math. 140 (2004), no 2, 359-395] and their higher-level
generalizations.


title: Search for the rare charmless hadronic decay B+ -> a0+ pi0

abstract:
  We present a search for B decays to a charged scalar meson a0+ and a pi0
where the a0+ decays to an eta meson and a pi+. The analysis was performed on a
data sample consisting of 383x10-6 BBbar pairs collected with the Babar
detector at the PEP-II asymmetric-energy B Factory at SLAC. We find no
significant signal and set an upper limit on the product branching fraction
BF[(B+ -> a0+ pi0) x (a0+ -> eta pi+)] of 1.4x10-6 at the 90% confidence level.


title: Nodally 3-connected planar graphs and convex combination mappings

abstract:
  A convex combination mapping of a planar graph is a plane mapping in which
the external vertices are mapped to the corners of a convex polygon and every
internal vertex is a proper weighted average of its neighbours. If a planar
graph is nodally 3-connected or triangulated then every such mapping is an
embedding (Tutte, Floater).
  We give a simple characterisation of nodally 3-connected planar graphs, and
generalise the above result to any planar graph which admits any convex
embedding.


title: Dephasing of a particle in a dissipative environment

abstract:
  The motion of a particle in a ring of length L is influenced by a dirty metal
environment whose fluctuations are characterized by a short correlation
distance $\ell << L$. We analyze the induced decoherence process, and compare
the results with those obtained in the opposing Caldeira-Leggett limit ($\ell
>> L$). A proper definition of the dephasing factor that does not depend on a
vague semiclassical picture is employed. Some recent Monte-Carlo results about
the effect of finite temperatures on "mass renormalization" in this system are
illuminated.


title:
The Aspherical Properties of the Energetic Type Ic SN 2002ap as Inferred
  from its Nebular Spectra

abstract:
  The nebular spectra of the broad-lined, SN 1998bw-like Type Ic SN 2002ap are
studied by means of synthetic spectra. Two different modelling techniques are
employed. In one technique, the SN ejecta are treated as a single zone, while
in the other a density and abundance distribution in velocity is used from an
explosion model. In both cases, heating caused by gamma-ray and positron
deposition is computed (in the latter case using a Monte Carlo technique to
describe the propagation of gamma-rays and positrons), as is cooling via
forbidden-line emission. The results are compared, and although general
agreement is found, the stratified models are shown to reproduce the observed
line profiles much more accurately than the single-zone model. The explosion
produced ~ 0.1 Msun of 56Ni. The distribution in velocity of the various
elements is in agreement with that obtained from the early-time models, which
indicated an ejected mass of ~ 2.5 Msun with a kinetic energy of 4 x 10^{51}
erg. Nebular spectroscopy confirms that most of the ejected mass (~ 1.2 Msun)
was oxygen. The presence of an oxygen-rich inner core, combined with that of
56Ni at high velocities as deduced from early-time models, suggests that the
explosion was asymmetric, especially in the inner part.


title: How to play a disc brake

abstract:
  We consider a gyroscopic system under the action of small dissipative and
non-conservative positional forces, which has its origin in the models of
rotating bodies of revolution being in frictional contact. The spectrum of the
unperturbed gyroscopic system forms a "spectral mesh" in the plane "frequency
-gyroscopic parameter" with double semi-simple purely imaginary eigenvalues at
zero value of the gyroscopic parameter. It is shown that dissipative forces
lead to the splitting of the semi-simple eigenvalue with the creation of the
so-called "bubble of instability" - a ring in the three-dimensional space of
the gyroscopic parameter and real and imaginary parts of eigenvalues, which
corresponds to complex eigenvalues. In case of full dissipation with a
positive-definite damping matrix the eigenvalues of the ring have negative real
parts making the bubble a latent source of instability because it can "emerge"
to the region of eigenvalues with positive real parts due to action of both
indefinite damping and non-conservative positional forces. In the paper, the
instability mechanism is analytically described with the use of the
perturbation theory of multiple eigenvalues. As an example stability of a
rotating circular string constrained by a stationary load system is studied in
detail. The theory developed seems to give a first clear explanation of the
mechanism of self-excited vibrations in the rotating structures in frictional
contact, that is responsible for such well-known phenomena of acoustics of
friction as the squealing disc brake and the singing wine glass.

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


title:
Estimating the proportion of differentially expressed genes in
  comparative DNA microarray experiments

abstract:
  DNA microarray experiments, a well-established experimental technique, aim at
understanding the function of genes in some biological processes. One of the
most common experiments in functional genomics research is to compare two
groups of microarray data to determine which genes are differentially
expressed. In this paper, we propose a methodology to estimate the proportion
of differentially expressed genes in such experiments. We study the performance
of our method in a simulation study where we compare it to other standard
methods. Finally we compare the methods in real data from two toxicology
experiments with mice.


title: One-way quantum computing in a decoherence-free subspace

abstract:
  We introduce a novel scheme for one-way quantum computing (QC) based on the
use of information encoded qubits in an effective cluster state resource. With
the correct encoding structure, we show that it is possible to protect the
entangled resource from phase damping decoherence, where the effective cluster
state can be described as residing in a Decoherence-Free Subspace (DFS) of its
supporting quantum system. One-way QC then requires either single or two-qubit
adaptive measurements. As an example where this proposal can be realized, we
describe an optical lattice setup where the scheme provides robust quantum
information processing. We also outline how one can adapt the model to provide
protection from other types of decoherence.


title: Supernovae in Three-Dimension: A Link to Gamma-Ray Bursts

abstract:
  Observational consequences of a jet-driven supernova (SN) explosion model are
presented. The results are compared in detail with optical observations of SN
1998bw associated with a Gamma-Ray Burst. It is shown that the jet model is
able to reproduce virtually all the optical observations available for this SN,
although a spherical model fails to explain some of observed features. Because
of the viewing angle effect, the required kinetic energy of the SN ejecta is
reduced to ~ 2 x 10^{52} erg as compared to that obtained by the previous
spherical model (~ 5 x 10^{52} erg), but this is still much larger than that of
a canonical SN (~10^{51} erg).


title: Ward Identities for the 2PI effective action in QED

abstract:
  We study the issue of symmetries and associated Ward-like identities in the
context of two-particle-irreducible (2PI) functional techniques for abelian
gauge theories. In the 2PI framework, the $n$-point proper vertices of the
theory can be obtained in various different ways which, although equivalent in
the exact theory, differ in general at finite approximation order. We derive
generalized (2PI) Ward identities for these various $n$-point functions and
show that such identities are exactly satisfied at any approximation order in
2PI QED. In particular, we show that 2PI-resummed vertex functions, i.e.
field-derivatives of the so-called 2PI-resummed effective action, exactly
satisfy standard Ward identities. We identify another set of $n$-point
functions in the 2PI framework which exactly satisfy the standard Ward
identities at any approximation order. These are obtained as field-derivatives
of the two-point function $\bcG^{-1}[\phi]$, which defines the extremum of the
2PI effective action. We point out that the latter is not constrained by the
underlying symmetry. As a consequence, the well-known fact that the
corresponding gauge-field polarization tensor is not transverse in momentum
space for generic approximations does not constitute a violation of (2PI) Ward
identities. More generally, our analysis demonstrates that approximation
schemes based on 2PI functional techniques respect all the Ward identities
associated with the underlying abelian gauge symmetry. Our results apply to
arbitrary linearly realized global symmetries as well.


title:
Probing the Explosion Mechanism of Supernovae by Radioactive Decay
  Gamma- and X-Rays

abstract:
  Gamma- and X-rays resulting from radioactive decays provide a potentially
powerful tool to investigate the explosion physics of supernovae, since the
distribution and the amount of radioactive isotopes are strongly dependent on
properties of the explosion. In this paper, expected features of these high
energy emissions are presented for bipolar jet-induced explosion models, which
are recently favored for very energetic supernovae and even for typical Type
Ib/c supernovae. It is shown that combination of various observations, i.e.,
line-to-continuum ratio, photoelectric absorption cut-off energy, line profiles
and luminosities, allows the unique determination of the explosion energy, the
amount of radioactive 56Ni, the explosion geometry, and even the viewing
orientation.


title:
Systematic {\it ab initio} study of the magnetic and electronic
  properties of all 3d transition metal linear and zigzag nanowires

abstract:
  It is found that all the zigzag chains except the nonmagnetic (NM) Ni and
antiferromagnetic (AF) Fe chains which form a twisted two-legger ladder, look
like a corner-sharing triangle ribbon, and have a lower total energy than the
corresponding linear chains. All the 3d transition metals in both linear and
zigzag structures have a stable or metastable ferromagnetic (FM) state. The
electronic spin-polarization at the Fermi level in the FM Sc, V, Mn, Fe, Co and
Ni linear chains is close to 90% or above. In the zigzag structure, the AF
state is more stable than the FM state only in the Cr chain. It is found that
the shape anisotropy energy may be comparable to the electronic one and always
prefers the axial magnetization in both the linear and zigzag structures. In
the zigzag chains, there is also a pronounced shape anisotropy in the plane
perpendicular to the chain axis. Remarkably, the axial magnetic anisotropy in
the FM Ni linear chain is gigantic, being ~12 meV/atom. Interestingly, there is
a spin-reorientation transition in the FM Fe and Co linear chains when the
chains are compressed or elongated. Large orbital magnetic moment is found in
the FM Fe, Co and Ni linear chains.


title: A representative sampling plan for auditing health insurance claims

abstract:
  A stratified sampling plan to audit health insurance claims is offered. The
stratification is by dollar amount of the claim. The plan is representative in
the sense that with high probability for each stratum, the difference in the
average dollar amount of the claim in the sample and the average dollar amount
in the population, is ``small.'' Several notions of ``small'' are presented.
The plan then yields a relatively small total sample size with the property
that the overall average dollar amount in the sample is close to the average
dollar amount in the population. Three different estimators and corresponding
lower confidence bounds for over (under) payments are studied.


title: Near Optimal Broadcast with Network Coding in Large Sensor Networks

abstract:
  We study efficient broadcasting for wireless sensor networks, with network
coding. We address this issue for homogeneous sensor networks in the plane. Our
results are based on a simple principle (IREN/IRON), which sets the same rate
on most of the nodes (wireless links) of the network. With this rate selection,
we give a value of the maximum achievable broadcast rate of the source: our
central result is a proof of the value of the min-cut for such networks, viewed
as hypergraphs. Our metric for efficiency is the number of transmissions
necessary to transmit one packet from the source to every destination: we show
that IREN/IRON achieves near optimality for large networks; that is,
asymptotically, nearly every transmission brings new information from the
source to the receiver. As a consequence, network coding asymptotically
outperforms any scheme that does not use network coding.


title: Confidence distribution (CD) -- distribution estimator of a parameter

abstract:
  The notion of confidence distribution (CD), an entirely frequentist concept,
is in essence a Neymanian interpretation of Fisher's Fiducial distribution. It
contains information related to every kind of frequentist inference. In this
article, a CD is viewed as a distribution estimator of a parameter. This leads
naturally to consideration of the information contained in CD, comparison of
CDs and optimal CDs, and connection of the CD concept to the (profile)
likelihood function. A formal development of a multiparameter CD is also
presented.


title:
From symmetry break to Poisson point process in 2D Voronoi
  tessellations: the generic nature of hexagons

abstract:
  We bridge the properties of the regular square and honeycomb Voronoi
tessellations of the plane to those of the Poisson-Voronoi case, thus analyzing
in a common framework symmetry-break processes and the approach to uniformly
random distributions of tessellation-generating points. We consider ensemble
simulations of tessellations generated by points whose regular positions are
perturbed through a Gaussian noise controlled by the parameter alpha. We study
the number of sides, the area, and the perimeter of the Voronoi cells. For
alpha>0, hexagons are the most common class of cells, and 2-parameter gamma
distributions describe well the statistics of the geometrical characteristics.
The symmetry break due to noise destroys the square tessellation, whereas the
honeycomb hexagonal tessellation is very stable and all Voronoi cells are
hexagon for small but finite noise with alpha<0.1. For a moderate amount of
Gaussian noise, memory of the specific unperturbed tessellation is lost,
because the statistics of the two perturbed tessellations is indistinguishable.
When alpha>2, results converge to those of Poisson-Voronoi tessellations. The
properties of n-sided cells change with alpha until the Poisson-Voronoi limit
is reached for alpha>2. The Desch law for perimeters is confirmed to be not
valid and a square root dependence on n is established. The ensemble mean of
the cells area and perimeter restricted to the hexagonal cells coincides with
the full ensemble mean; this might imply that the number of sides acts as a
thermodynamic state variable fluctuating about n=6; this reinforces the idea
that hexagons, beyond their ubiquitous numerical prominence, can be taken as
generic polygons in 2D Voronoi tessellations.

categories: cond-mat.stat-mech cond-mat.dis-nn cs.CG math-ph math.MP physics.data-an


title:
Empirical Bayes methods for controlling the false discovery rate with
  dependent data

abstract:
  False discovery rate (FDR) has been widely used as an error measure in large
scale multiple testing problems, but most research in the area has been focused
on procedures for controlling the FDR based on independent test statistics or
the properties of such procedures for test statistics with certain types of
stochastic dependence. Based on an approach proposed in Tang and Zhang (2005),
we further develop in this paper empirical Bayes methods for controlling the
FDR with dependent data. We implement our methodology in a time series model
and report the results of a simulation study to demonstrate the advantages of
the empirical Bayes approach.


title:
A new doubly discrete analogue of smoke ring flow and the real time
  simulation of fluid flow

abstract:
  Modelling incompressible ideal fluids as a finite collection of vortex
filaments is important in physics (super-fluidity, models for the onset of
turbulence) as well as for numerical algorithms used in computer graphics for
the real time simulation of smoke. Here we introduce a time-discrete evolution
equation for arbitrary closed polygons in 3-space that is a discretisation of
the localised induction approximation of filament motion. This discretisation
shares with its continuum limit the property that it is a completely integrable
system. We apply this polygon evolution to a significant improvement of the
numerical algorithms used in Computer Graphics.


title: A smoothing model for sample disclosure risk estimation

abstract:
  When a sample frequency table is published, disclosure risk arises when some
individuals can be identified on the basis of their values in certain
attributes in the table called key variables, and then their values in other
attributes may be inferred, and their privacy is violated. On the basis of the
sample to be released, and possibly some partial knowledge of the whole
population, an agency which considers releasing the sample, has to estimate the
disclosure risk. Risk arises from non-empty sample cells which represent small
population cells and from population uniques in particular. Therefore risk
estimation requires assessing how many of the relevant population cells are
likely to be small. Various methods have been proposed for this task, and we
present a method in which estimation of a population cell frequency is based on
smoothing using a local neighborhood of this cell, that is, cells having
similar or close values in all attributes. We provide some preliminary results
and experiments with this method. Comparisons are made to two other methods: 1.
a log-linear models approach in which inference on a given cell is based on a
``neighborhood'' of cells determined by the log-linear model. Such
neighborhoods have one or some common attributes with the cell in question, but
some other attributes may differ significantly. 2 The Argus method in which
inference on a given cell is based only on the sample frequency in the specific
cell, on the sample design and on some known marginal distributions of the
population, without learning from any type of ``neighborhood'' of the given
cell, nor from any model which uses the structure of the table.


title: A note on the U,V method of estimation

abstract:
  The U,V method of estimation provides unbiased estimators or predictors of
random quantities. The method was introduced by Robbins \citer3 and
subsequently studied in a series of papers by Robbins and Zhang. (See Zhang
\citer5.) Practical applications of the method are featured in these papers. We
demonstrate that for one U function (one for which there is an important
application) the V estimator is inadmissible for a wide class of loss
functions. For another important U function the V estimator is admissible for
the squared error loss function.


title:
Low-power radio galaxy environments in the Subaru/XMM-Newton Deep Field
  at z~0.5

abstract:
  We present multi-object spectroscopy of galaxies in the immediate (Mpc-scale)
environments of four low-power (L_1.4 GHz < 10^25 W/Hz) radio galaxies at
z~0.5, selected from the Subaru/XMM-Newton Deep Field. We use the spectra to
calculate velocity dispersions and central redshifts of the groups the radio
galaxies inhabit, and combined with XMM-Newton (0.3-10 keV) X-ray observations
investigate the L_X--sigma_v and T_X--sigma_v scaling relationships. All the
radio galaxies reside in moderately rich groups -- intermediate environments
between poor groups and rich clusters, with remarkably similar X-ray
properties. We concentrate our discussion on our best statistical example that
we interpret as a low-power (FRI) source triggered within a sub-group, which in
turn is interacting with a nearby group of galaxies, containing the bulk of the
X-ray emission for the system -- a basic scenario which can be compared to more
powerful radio sources at both high (z>4) and low (z<0.1) redshifts. This
suggests that galaxy-galaxy interactions triggered by group mergers may play an
important role in the life-cycle of radio galaxies at all epochs and
luminosities.


title: Local polynomial regression on unknown manifolds

abstract:
  We reveal the phenomenon that ``naive'' multivariate local polynomial
regression can adapt to local smooth lower dimensional structure in the sense
that it achieves the optimal convergence rate for nonparametric estimation of
regression functions belonging to a Sobolev space when the predictor variables
live on or close to a lower dimensional manifold.


title: Microscopic quark study of the eta and eta' masses

abstract:
  We show that it is necessary to go beyond the BCS (rainbow-ladder)
approximation to split the $\eta$ and $\eta'$ masses from the $\pi$ and K
masses. We determine the self-consistent set of one-quark-loop diagrams both
for the Schwinger-Dyson quark mass gap equation and for the Bethe-Salpeter
quark-antiquark boundstate equation. We identify the dominant diagrams, and we
focus on the boundstate equation. We detail the Bethe-Salpeter equation, adding
the dominant new diagram to the BCS kernel. The relevant numerical techniques
are also discussed. The ideal cases of one, two and three light flavors,
relevant to lattice QCD are also explored, together with the case of realistic
current quark masses.


title: Formal punctured ribbons and two-dimensional local fields

abstract:
  We investigate formal ribbons on curves. Roughly speaking, formal ribbon is a
family of locally linearly compact vector spaces on a curve. We establish a
one-to-one correspondence between formal ribbons on curves plus some geometric
data and some subspaces of two-dimensional local field.


title:
Accurate early positions for Swift GRBS: enhancing X-ray positions with
  UVOT astrometry

abstract:
  Here we describe an autonomous way of producing more accurate prompt XRT
positions for Swift-detected GRBs and their afterglows, based on UVOT
astrometry and a detailed mapping between the XRT and UVOT detectors. The
latter significantly reduces the dominant systematic error -- the star-tracker
solution to the World Coordinate System. This technique, which is limited to
times when there is significant overlap between UVOT and XRT PC-mode data,
provides a factor of 2 improvement in the localisation of XRT refined positions
on timescales of less than a few hours. Furthermore, the accuracy achieved is
superior to astrometrically corrected XRT PC mode images at early times (for up
to 24 hours), for the majority of bursts, and is comparable to the accuracy
achieved by astrometrically corrected X-ray positions based on deep XRT PC-mode
imaging at later times (abridged).


title: Darwinian Dynamics Implies Developmental Ascendency

abstract:
  A tendency in biological theorizing is to formulate principles above or equal
to Evolution by Variation and Selection of Darwin and Wallace. In this letter I
analyze one such recent proposal which did so for the developmental ascendency.
I show that though the idea of developmental ascendency is brilliant, this is
in wrong order in the hierarchical structure of biological theories and can
easily generate confusing. Several other examples are also briefly discussed in
the note added.


title: The role of the two postulates of special relativity

abstract:
  Students are often mystified by the reasoning that leads from the postulates
of special relativity to the requirement of covariance. This is partly due to
the lack of transparency resulting from the failure to clearly separate the
roles the postulates of the constancy of the speed of light and of relativity
play. Their roles are elucidated here by mainly geometric means. Finally some
standard derivations found in textbooks are analyzed in order to sort out the
basic physical ingredients.


title:
Proton Hexality from an Anomalous Flavor U(1) and Neutrino Masses -
  Linking to the String Scale

abstract:
  We devise minimalistic gauged U(1)_X Froggatt-Nielsen models which at
low-energy give rise to the recently suggested discrete gauge Z_6 symmetry,
proton hexality, thus stabilizing the proton. Assuming three generations of
right-handed neutrinos, with the proper choice of X-charges, we obtain viable
neutrino masses. Furthermore, we find scenarios such that no X-charged hidden
sector superfields are needed, which from a bottom-up perspective allows the
calculation of g_string, g_X and G_SM's Kac-Moody levels. The only mass scale
apart from M_grav is m_soft.


title:
Matrice magique associ\'ee \`a un germe de courbe plane et division par
  l'id\'eal Jacobien

abstract:
  In the ring of holomorphic functions at the origin of C^2, we consider the
equation uf'_x+vf'_y=wf where f and w are given. We introduce intersection
multiplicities relative to w and f'_y along the branches of f, and we study the
solutions (u,v) using these valuations. As an application, we construct an
explicit functional equation satisfied by f.


title: Full transmission through perfect-conductor subwavelength hole arrays

abstract:
  Light transmission through 2D subwavelength hole arrays in perfect-conductor
films is shown to be complete (100%) at some resonant wavelengths even for
arbitrarily narrow holes. Conversely, the reflection on a 2D planar array of
non-absorbing scatterers is shown to be complete at some wavelengths regardless
how weak the scatterers are. These results are proven analytically and
corroborated by rigorous numerical solution of Maxwell's equations. This work
supports the central role played by dynamical diffraction during light
transmission through subwavelength hole arrays and it provides a systematics to
analyze more complex geometries and many of the features observed in connection
with transmission through hole arrays.