title:
Evolution from Itinerant Antiferromagnet to Unconventional
  Superconductor with Fluorine Doping in La(O_{1-x}F_{x})FeAs Revealed by
  ^{75}As and ^{139}La Nuclear Magnetic Resonance

abstract:
  We report experimental results of ^{75}As and ^{139}La nuclear magnetic
resonance (NMR) in the iron-based layered La(O_{1-x}F_{x})FeAs (x= 0.0, 0.04
and 0.11) system. In the undoped LaOFeAs, 1/T_1 of ^{139}La exhibits a distinct
peak at T_N ~ 142 K below which the spectra become broadened due to the
internal magnetic field attributed to an antiferromagnetic (AFM) ordering. In
the 4% F-doped sample, 1/T_1T exhibits a Curie-Weiss temperature dependence
down to 30 K, suggesting the development of AFM spin fluctuations with
decreasing temperature. In the 11% F-doped sample, in contrast, pseudogap
behavior is observed in 1/T_1T both at the ^{75}As and ^{139}La site with a gap
value of ~172 K. The spin dynamics vary markedly with F doping, which is
ascribed to the Fermi-surface structure. As for the superconducting properties
for the 4% and 11% F-doped samples, 1/T_1 in both compounds does not exhibit a
coherence peak just below T_c and follows a T^3 dependence at low temperatures,
which suggests unconventional superconductivity with line-nodes. We discuss
similarities and differences between La(O_{1-x}F_{x})FeAs and cuprates, and
also discuss the relationship between spin dynamics and superconductivity on
the basis of F doping dependence of T_c and 1/T_1.


title:
Quantum Theory of Transmission Line Resonator-Assisted Cooling of a
  Micromechanical Resonator

abstract:
  We propose a quantum description of the cooling of a micromechanical flexural
oscillator by a one-dimensional transmission line resonator via a force that
resembles cavity radiation pressure. The mechanical oscillator is capacitively
coupled to the central conductor of the transmission line resonator. At the
optimal point, the micromechanical oscillator can be cooled close to the ground
state, and the cooling can be measured by homodyne detection of the output
microwave signal.


title: The defect of weak approximation for homogeneous spaces. II

abstract:
  Let X be a homogeneous space of a connected linear algebraic group G' over a
number field k, containing a k-point x. Assume that the stabilizer of x in G'
is connected. Using the notion of a quasi-trivial group, recently introduced by
Colliot-Th\'el\`ene, we can represent X in the form X=G/H, where G is a
quasi-trivial k-group and H is a connected k-subgroup of G. Let S be a finite
set of places of k. Applying results of [B2], we compute the defect of weak
approximation for X with respect to S in terms of the biggest toric quotient T
of H. In particular, we show that if T splits over a metacyclic extension of k,
then X has the weak approximation property. We show also that any homogeneous
space X with connected stabilizer (without assumptions on T) has the real
approximation property.


title: Crumpling under an ambient pressure

abstract:
  A pressure chamber is designed to study the crumpling process under an
ambient force. The compression force and its resulting radius for the ball obey
a power law with an exponent that is independent of the thickness and initial
size of the sheet. However, the exponent is found to be material-dependent and
less than the universal value, 0.25, claimed by the previous simulations. The
power law behavior disappears at high pressure when the compressibility drops
discontinuously, which is suggestive of a jammed state.


title: Quantum motion effects in an ultracold-atom Mach-Zehnder interferometer

abstract:
  We study the effect of quantum motion in a Mach-Zehnder interferometer where
ultracold, two-level atoms cross a $\pi/2 $-$\pi $-$\pi/2$ configuration of
separated, laser illuminated regions. Explicit and exact expressions are
obtained for transmission amplitudes of monochromatic, incident atomic waves
using recurrence relations which take into account all possible paths: the
direct ones usually considered in the simple semiclassical treatment, but
including quantum motion corrections, and the paths in which the atoms are
repeatedly reflected at the fields.


title:
Measurement of branching fractions, isospin and CP-violating asymmetries
  for exclusive \boldmath$b \to d\gamma$ modes

abstract:
  We report new measurements of the decays $B\to\rho^+ \gamma$, $B \to \rho^0
\gamma$ and $B \to \omega\gamma$ using a data sample of $657 \times 10^6$ $B$
meson pairs accumulated with the Belle detector at the KEKB $e^+ e^-$ collider.
We measure branching fractions ${\cal B}(B^+ \to \rho^+ \gamma) =
(8.7^{+2.9}_{-2.7}{}^{+0.9}_{-1.1})\times 10^{-7}$, ${\cal B}(B^0 \to \rho^0
\gamma) = (7.8^{+1.7}_{-1.6}{}^{+0.9}_{-1.0}) \times 10^{-7}$ and ${\cal B}(B^0
\to \omega \gamma) = (4.0^{+1.9}_{-1.7} \pm 1.3) \times 10^{-7}$. We also
report the isospin asymmetry $\Delta (\rho\gamma) =
-0.48^{+0.21}_{-0.19}{}^{+0.08}_{-0.09}$; and the first measurement of the
direct CP-violating asymmetry $A_{CP}(B^+ \to \rho^+ \gamma) =
-0.11\pm{0.32}\pm{0.09}$, where the first and second errors are statistical and
systematic, respectively.


title:
First-principles investigation of symmetric and antisymmetric exchange
  interactions of SrCu$_{2}$(BO$_{3}$)$_{2}$

abstract:
  We report on a first-principles investigation of the electronic structure and
of the magnetic properties of the quasi-two-dimensional Mott insulator
SrCu$_{2}$(BO$_{3}$)$_{2}$. Based on the hopping integrals and Coulomb
interactions calculated with LDA and LSDA+U, we provide a microscopic
explanation of the symmetric Heisenberg and antisymmetric Dzyaloshinskii-Moriya
exchange integrals of SrCu$_{2}$(BO$_{3}$)$_{2}$. The intra-atomic exchange
interaction of oxygen is shown to strongly contribute to the intra-dimer
isotropic exchange. The results are in good agreement with those derived from
experimental data, both regarding the orientation of the Dzyaloshinskii-Moriya
vectors and the magnitude of all exchange integrals. The microscopic analysis
is confirmed by the results of Green function's and total energies difference
methods.


title: Dimers on graphs in non-orientable surfaces

abstract:
  The main result of this paper is a Pfaffian formula for the partition
function of the dimer model on a graph G embedded in a closed, possibly
non-orientable surface S. This formula is suitable for computational purposes,
and it is obtained using purely geometrical methods. The key step in the proof
consists of a correspondence between some orientations on G and the set of
pin^- structures on S. This generalizes (and simplifies) the results of a
previous paper [2].


title: The small axial charge of the N(1535) resonance

abstract:
  There is a natural cancellation between the contributions of the $qqq$ and
$qqqq\bar q$ components to the axial charge of the N(1535) resonance. While the
probability of the former is larger than that of the latter, its coefficient in
the axial charge expression is exceptionally small. The magnitude of two of the
corresponding coefficients of the $qqqq\bar q$ components are in contrast large
and have the opposite sign. This result provides a phenomenological
illustration of the recent unquenched lattice calculation result that the axial
charge of the N(1535) resonance is very small, if not vanishing \cite{takah}.
The result sets an upper limit on the magnitude of the probability of $qqqq\bar
q$ components as well.


title:
A Projection Method for Derivation of Non-Shannon-Type Information
  Inequalities

abstract:
  In 1998, Zhang and Yeung found the first unconditional non-Shannon-type
information inequality. Recently, Dougherty, Freiling and Zeger gave six new
unconditional non-Shannon-type information inequalities. This work generalizes
their work and provides a method to systematically derive non-Shannon-type
information inequalities. An application of this method reveals new 4-variable
non-Shannon-type information inequalities.


title:
Perturbative study of the Kitaev model with spontaneous time-reversal
  symmetry breaking

abstract:
  We analyze the Kitaev model on the triangle-honeycomb lattice whose ground
state has recently been shown to be a chiral spin liquid. We consider two
perturbative expansions: the isolated-dimer limit containing Abelian anyons and
the isolated-triangle limit. In the former case, we derive the low-energy
effective theory and discuss the role played by multi-plaquette interactions.
In this phase, we also compute the spin-spin correlation functions for any
vortex configuration. In the isolated-triangle limit, we show that the
effective theory is, at lowest nontrivial order, the Kitaev honeycomb model at
the isotropic point. We also compute the next-order correction which opens a
gap and yields non-Abelian anyons.


title: Pionization and Energy Loss

abstract:
  This is a version submitted to proceedings of sqm09. The space time of hard
interaction induced radiation (collinear, double log) and
jet-QGM-interaction-induced radiation (bremsstrahlung + pionization) is more
clarified. A hand-drawing picture is attached for interested reader. To measure
y=1.2 to 2.2 more suppressed (than y=0) open charm pT spectrum is predicted and
suggested as a good test.


title: Coinage-metal capping effects on the spin-reorientations of Co/Ru(0001)

abstract:
  Thin films of Co/Ru(0001) are known to exhibit an unusual spin reorientation
transition (SRT) coupled to the completion of Co atomic layers for Co
thicknesses under 4 layers. By means of spin-polarized low-energy electron
microscopy, we follow in real space the magnetization orientation during the
growth of atomically thick capping layers on Co/Ru(0001). Capping with
coinage-metal (Cu, Ag, Au) elements modifies the SRT depending on the Co and
overlayer thickness and on the overlayer material, resulting in an expanded
range of structures with high perpendicular magnetic anisotropy. The origin of
the SRT can be explained in terms of ab-initio calculations of the
layer-resolved contributions to the magnetic anisotropy energy. Besides the
changes in the SRT introduced by the capping, a quantitative enhancement of the
magnetic anisotropy is identified. A detailed analysis of the interplay between
strain and purely electronic effects allows us to identify the conditions that
lead to a high perpendicular magnetic anisotropy in thin hcp Co films.


title:
Compact complete proper minimal immersions in strictly convex bounded
  regular domains of R^3

abstract:
  Consider a strictly convex bounded regular domain $C$ of $\R^3$. For any
arbitrary finite topological type we find a compact Riemann surface
$\mathcal{M}$, an open domain $M\subset \mathcal{M}$ with the fixed topological
type, and a conformal complete proper minimal immersion $X:M\to C$ which can be
extended to a continuous map $X:\overline{M}\to \overline{C}$.


title:
Updated SM calculations of sigma_W/sigma_Z at the Tevatron and the W
  boson width

abstract:
  The central value and theoretical uncertainties on the cross section ratio
sigma_W/sigma_Z at the Tevatron are evaluated using the NNLO calculations and
the latest MSTW PDFs. The partial width, total width and branching ratios of
the W boson in the Standard Model, in the light of the latest electroweak
calculations, are also updated.


title:
Incorporating a contrast in the Bayesian formula: What consequences for
  the MAP estimator and the posterior distribution? Applications in spatial
  statistics

abstract:
  In order to estimate model parameters and circumvent possible difficulties
encountered with the likelihood function, we propose to replace the likelihood
in the formula of the posterior distribution by a function depending on a
contrast. The properties of the contrast-based (CB) posterior distribution and
MAP estimator are studied to understand what the consequences of incorporating
a contrast in the Bayesian formula are. We show that the proposed method can be
used to make frequentist inference and allows the reduction of analytical
calculations to get the limit variance matrix of the estimator. For specific
contrasts, the CB--posterior distribution directly approximates the limit
distribution of the estimator; the calculation of the limit variance matrix is
then avoided. Moreover, for these contrasts, the CB--posterior distribution can
also be used to make inference in the Bayesian way. The method is applied to
three spatial data sets.


title:
The symmetry of the spin Hamiltonian in herbertsmithite, a spin-1/2
  kagom\'{e} lattice

abstract:
  We present magnetization measurements on oriented powder of
ZnCu$_{3}$(OH)$_{6}$Cl$_{2}$ along and perpendicular to the orienting field. We
find a dramatic difference in the magnetization between the two directions. It
is biggest at low measurement fields $H$ or high temperatures. We show that the
difference at high temperatures must emerge from Ising-like exchange
anisotropy. This allows us to explain muon spin rotation data at $T\to 0$ in
terms of an exotic ferromagnetic ground state.


title: Vacuum Energy and Standard Model Physics

abstract:
  The conditions for the cancellation of one loop contributions to vacuum
energy (both U.V. divergent and finite) coming from the Standard Model (SM)
fields are examined. It is proven that this is not possible unless one
introduces besides several bosons, at least one massive fermion having mass
within specific ranges. On examining one of the simplest SM extensions
satisfying the constraints one finds that the mass range of the lightest
massive boson is compatible with the present Higgs mass bounds. We do not
consider effects associated with condensates or renormalization group running.


title: Effect of Pions in Cosmic Rays

abstract:
  The effects of pions for vacuum polarization in background magnetic fields
are considered. The effects of quark condensates is also briefly addresses.
Although these effects are out of the measurement accuracy of laboratory
experiments they may be relevant for gamma-ray burst propagation. In
particular, for emissions from the center of the galaxy, we show that the
mixing between the neutral pion and photons results in a deviation of the
gamma-ray spectrum from the standard power-law in the TeV range.


title: Generating functions for black hole entropy in Loop Quantum Gravity

abstract:
  We introduce, in a systematic way, a set of generating functions that solve
all the different combinatorial problems that crop up in the study of black
hole entropy in Loop Quantum Gravity. Specifically we give generating functions
for: The different sources of degeneracy related to the spectrum of the area
operator, the solutions to the projection constraint, and the black hole
degeneracy spectrum. Our methods are capable of handling the different
countings proposed and discussed in the literature. The generating functions
presented here provide the appropriate starting point to extend the results
already obtained for microscopic black holes to the macroscopic regime --in
particular those concerning the area law and the appearance of an effectively
equidistant area spectrum.


title: Higher-order Cartan symmetries in k-symplectic field theory

abstract:
  For k-symplectic Hamiltonian field theories, we study infinitesimal
transformations generated by certain kinds of vector fields which are not
Noether symmetries, but which allow us to obtain conservation laws by means of
a suitable generalization of the Noether theorem.


title: Skyrmion Vibration Modes within the Rational Map Ansatz

abstract:
  We study the vibration modes of the Skyrme model within the rational map
ansatz. We show that the vibrations of the radial profiles and the rational
maps are decoupled and we consider explicitly the case B=1, B=2 and B=4. We
then compare our results with the vibration modes obtained numerically by
Barnes et al. and show that qualitatively the rational map reproduces the
vibration modes obtained numerically but that the vibration frequencies of
these modes do not match very well.


title: Weak mirror symmetry of Lie algebras

abstract:
  The existence of a flat torsion-free connection, or left symmetric algebra
structure on a Lie algebra g gives rise to a canonically defined complex
structure on g+g and a symplectic structure on g+g^*. We verify that the
associated differential Gerstenhaber algebras controlling the deformation
theories of the complex and symplectic form are isomorphic. This provides a
class of examples of "weak mirror symmetry" as suggested by Merkulov. For
nilpotent algebras in dimension 4 and 6 the isomorphism classes of the
semi-direct products g+g and g+g^* are listed. A one-parameter family of
inequivalent pseudo-K\"ahler structures is given.


title: High Resolution Imaging of Single Atoms in a Quantum Gas

abstract:
  Our knowledge on ultracold quantum gases is strongly influenced by our
ability to probe these objects. In situ imaging combined with single atom
sensitivity is an especially appealing scenario as it can provide direct
information on the structure and the correlations of such systems. For a
precise characterization a high spatial resolution is mandatory. In particular,
the perspective to study quantum gases in optical lattices makes a resolution
well below one micrometer highly desirable. Here, we report on a novel
microscopy technique which is based on scanning electron microscopy and allows
for the detection of single atoms inside a quantum gas with a spatial
resolution of better than 150 nm. Imaging a Bose-Einstein condensate in a
one-dimensional optical lattice with 600 nm period we demonstrate single site
addressability in a sub-um optical lattice. The technique offers exciting
possibilities for the preparation, manipulation and analysis of quantum gases.


title: The abelianization of the level 2 mapping class group

abstract:
  In this paper, we determine the abelianization of the level d mapping class
group for d=2 and odd d. We also extend the homomorphism of the Torelli group
defined by Heap to a homomorphism of the level 2 mapping class group.


title: Hyperbolic graphs of small complexity

abstract:
  In this paper we enumerate and classify the ``simplest'' pairs (M,G) where M
is a closed orientable 3-manifold and G is a trivalent graph embedded in M.
  To enumerate the pairs we use a variation of Matveev's definition of
complexity for 3-manifolds, and we consider only (0,1,2)-irreducible pairs,
namely pairs (M,G) such that any 2-sphere in M intersecting G transversely in
at most 2 points bounds a ball in M either disjoint from G or intersecting G in
an unknotted arc. To classify the pairs our main tools are geometric invariants
defined using hyperbolic geometry. In most cases, the graph complement admits a
unique hyperbolic structure with parabolic meridians; this structure was
computed and studied using Heard's program Orb and Goodman's program Snap.
  We determine all (0,1,2)-irreducible pairs up to complexity 5, allowing
disconnected graphs but forbidding components without vertices in complexity 5.
The result is a list of 129 pairs, of which 123 are hyperbolic with parabolic
meridians. For these pairs we give detailed information on hyperbolic
invariants including volumes, symmetry groups and arithmetic invariants.
Pictures of all hyperbolic graphs up to complexity 4 are provided. We also
include a partial analysis of knots and links.
  The theoretical framework underlying the paper is twofold, being based on
Matveev's theory of spines and on Thurston's idea (later developed by several
authors) of constructing hyperbolic structures via triangulations. Many of our
results were obtained (or suggested) by computer investigations.


title: Detectability of gamma-ray emission from classical novae with Swift/BAT

abstract:
  Classical novae are expected to emit gamma rays during their explosions. The
most important contribution to the early gamma-ray emission comes from the
annihilation with electrons of the positrons generated by the decay of 13N and
18F. The photons are expected to be down-scattered to a few tens of keV, and
the emission is predicted to occur some days before the visual discovery and to
last ~2 days. Despite a number of attempts, no positive detections of such
emission have been made, due to lack of sensitivity and of sky coverage.
Because of its huge field of view, good sensitivity, and well-adapted energy
band, Swift/BAT offers a new opportunity for such searches. BAT data can be
retrospectively used to search for prompt gamma-ray emission from the direction
of novae after their optical discovery. We have estimated the expected success
rate for the detection with BAT of gamma rays from classical novae using a
Monte Carlo approach. Searches were performed for emission from novae occurring
since the launch of Swift. Using the actual observing program during the first
2.3 years of BAT operations as an example, and sensitivity achieved, we
estimate the expected rate of detection of classical novae with BAT as
~0.2-0.5/yr, implying that several should be seen within a 10 yr mission. The
search for emission in the directions of the 24 classical novae discovered
since the Swift launch yielded no positive results, but none of these was known
to be close enough for this to be a surprise. Detections of a recurrent nova
(RS Oph) and a nearby dwarf nova (V455 And) demonstrate the efficacy of the
technique. The absence of detections is consistent with the expectations from
the Monte Carlo simulations, but the long-term prospects are encouraging given
an anticipated Swift operating lifetime of ~10 years.


title:
Slowing light through Zeeman Coherence Oscillations in a duplicated
  two-level system

abstract:
  We present the theory of a new method to slow a linearly polarized probe
pulse as it propagates through a duplicated two-level system driven by an
orthogonally polarized control field. The method makes use of Zeeman coherence
oscillations (CZO) that arise in the atomic system because of the spatial and
temporal modulation of the total polarization. This method exhibits properties
similar to those that rely on the electromagnetically induced transparency
(EIT) but without the existence of any trapping state. We demonstrated also the
propagation of a dark polariton in the medium


title: SU(3) dibaryons in the Einstein-Skyrme model

abstract:
  SU(3) collective coordinate quantization to the regular solution of the B=2
axially symmetric Einstein-Skyrme system is performed. For the symmetry
breaking term, a perturbative treatment as well as the exact diagonalization
method called Yabu-Ando approach are used. The effect of the gravity on the
mass spectra of the SU(3) dibaryons and the symmetry breaking term is studied
in detail. In the strong gravity limit, the symmetry breaking term
significantly reduces and exact SU(3) flavor symmetry is recovered.


title: Local Magnetic Properties of a Monolayer of Mn12 Single Molecule Magnets

abstract:
  The magnetic properties of a monolayer of Mn12 single molecule magnets
grafted onto a Si substrate have been investigated using depth-controlled
$\beta$-detected nuclear magnetic resonance. A low energy beam of spin
polarized radioactive 8Li was used to probe the local static magnetic field
distribution near the Mn12 monolayer in the Si substrate. The resonance
linewidth varies strongly as a function of implantation depth as a result of
the magnetic dipolar fields generated by the Mn12 electronic magnetic moments.
The temperature dependence of the linewidth indicates that the magnetic
properties of the Mn12 moments in this low dimensional configuration differ
from bulk Mn12.


abstract:
  Let $R$ be a commutative Noetherian ring. The notion of regular sequences
with respect to a Serre class of $R$-modules is introduced and some of their
essential properties are given. Then in the local case, we explore a theory of
Cohen-Macaulayness with respect to Serre classes.


title: Heuristic model of teaching

abstract:
  A simple physical model differentiates effective from ineffective teaching
and identifies elements that make teaching productive, with specific
implications concerning training of teachers.


title: Quantum states for perfectly secure secret sharing

abstract:
  In this work, we investigate what kinds of quantum states are feasible to
perform perfectly secure secret sharing, and present its necessary and
sufficient conditions. We also show that the states are bipartite distillable
for all bipartite splits, and hence the states could be distillable into the
Greenberger-Horne-Zeilinger state. We finally exhibit a class of secret-sharing
states, which have an arbitrarily small amount of bipartite distillable
entanglement for a certain split.


title:
Clusters of Galaxies in the First Half of the Universe from the IRAC
  Shallow Survey

abstract:
  We have identified 335 galaxy cluster and group candidates, 106 of which are
at z > 1, using a 4.5 um selected sample of objects from a 7.25 deg^2 region in
the Spitzer Infrared Array Camera (IRAC) Shallow Survey. Clusters were
identified as 3-dimensional overdensities using a wavelet algorithm, based on
photometric redshift probability distributions derived from IRAC and NOAO Deep
Wide-Field Survey data. We estimate only ~10% of the detections are spurious.
To date 12 of the z > 1 candidates have been confirmed spectroscopically, at
redshifts from 1.06 to 1.41. Velocity dispersions of ~750 km/s for two of these
argue for total cluster masses well above 10^14 M_sun, as does the mass
estimated from the rest frame near infrared stellar luminosity. Although not
selected to contain a red sequence, some evidence for red sequences is present
in the spectroscopically confirmed clusters, and brighter galaxies are
systematically redder than the mean galaxy color in clusters at all redshifts.
The mean I - [3.6] color for cluster galaxies up to z ~ 1 is well matched by a
passively evolving model in which stars are formed in a 0.1 Gyr burst starting
at redshift z_f = 3. At z > 1, a wider range of formation histories is needed,
but higher formation redshifts (i.e. z_f > 3) are favored for most clusters.


title: A Few More Quadratic APN Functions

abstract:
  We present two infinite families of APN functions where the degree of the
field is divisible by 3 but not 9. Our families contain two already known
families as special cases. We also discuss the inequivalence proof (by
computation) which shows that these functions are new.


title: Borel-amenable Reducibilities for Sets of Reals

abstract:
  We show that if $\mathcal{F}$ is any "well-behaved" subset of the Borel
functions and we assume the Axiom of Determinacy then the hierarchy of degrees
on $\pow(\mathbb{R})$ induced by $\mathcal{F}$ turns out to look like the Wadge
hierarchy (which is the special case where $\mathcal{F}$ is the set of
continuous functions).


title:
Role of Tachyonic Field in Accelerating Universe in Presence of Perfect
  Fluid

abstract:
  Recently tachyonic field has been depicted as dark energy model to represent
the present acceleration of the Universe. In this paper we have considered
mixture of tachyonic fluid with a perfect fluid. For this purpose we have
considered barotropic fluid and Generalized Chaplygin gas(G.C.G.). We have
considered a particular form of the scale factor. We have solved the equations
of motion to get the exact solutions of the density, tachyonic potential and
the tachyonic field. We have introduced a coupling term to show that the
interaction decays with time. Also we have shown that the nature of the
potentials vary so as the interaction term reduces the potential in both the
cases.


title: Principles of the motion of fluids

abstract:
  This is an English translation of Euler's article "Principia motus fluidorum"
in which the Euler equation (in two three dimensions) has been established for
the first time in 1752. The actual publication has been delayed by nine years.
Finally, this article has been published in 1761 in Novi Commentarii Academiae
Scientiarum Petropolitanae.


title: Rolling ferrofluid drop on the surface of a liquid

abstract:
  We report on the controlled transport of drops of magnetic liquid, which are
swimming on top of a non-magnetic liquid layer. A magnetic field which is
rotating in a vertical plane creates a torque on the drop. Due to surface
stresses within the immiscible liquid beneath, the drop is propelled forward.
We measure the drop speed for different field amplitudes, field frequencies and
drop volumes. Simplifying theoretical models describe the drop either as a
solid sphere with a Navier slip boundary condition, or as a liquid half-sphere.
An analytical expression for the drop speed is obtained which is free of any
fitting parameters and is well in accordance with the experimental
measurements. Possible microfluidic applications of the rolling drop are also
discussed.


title:
From cellular properties to population asymptotics in the Population
  Balance Equation

abstract:
  Proliferating cell populations at steady state growth often exhibit broad
protein distributions with exponential tails. The sources of this variation and
its universality are of much theoretical interest. Here we address the problem
by asymptotic analysis of the Population Balance Equation. We show that the
steady state distribution tail is determined by a combination of protein
production and cell division and is insensitive to other model details. Under
general conditions this tail is exponential with a dependence on parameters
consistent with experiment. We discuss the conditions for this effect to be
dominant over other sources of variation and the relation to experiments.


title:
Local supersymmetric extensions of the Poincare and AdS invariant
  gravity

abstract:
  In all the odd dimensions which allow Majorana spinors, we consider a
gravitational Lagrangian possessing local Poincare invariance and given by the
dimensional continuation of the Euler density in one dimension less. We show
that the local supersymmetric extension of this Lagrangian requires the algebra
to be the maximal extension of the N=1 super-Poincare algebra. By maximal, we
mean that in the right hand side of the anticommutator of the Majorana super
charge appear all the possible central charges. The resulting action defines a
Chern-Simons gauge theory for the maximal extension of the super-Poincare
algebra. In these dimensions, we address the same problem for the AdS invariant
gravity and we derive its supersymmetric extension for the minimal super-AdS
algebra. The connection between both models is realized at the algebraic level
through an expansion of their corresponding Lie super algebras. Within a
procedure consistent with the expansion of the algebras, the local
supersymmetric extension of the Poincare invariant gravity Lagrangian is
derived from the super AdS one.


title: Accelerator Disaster Scenarios, the Unabomber, and Scientific Risks

abstract:
  The possibility that experiments at high-energy accelerators could create new
forms of matter that would ultimately destroy the Earth has been considered
several times in the past quarter century. One consequence of the earliest of
these disaster scenarios was that the authors of a 1993 article in "Physics
Today" who reviewed the experiments that had been carried out at the Bevalac at
Lawrence Berkeley Laboratory were placed on the FBI's Unabomber watch list.
Later, concerns that experiments at the Relativistic Heavy Ion Collider at
Brookhaven National Laboratory might create mini black holes or nuggets of
stable strange quark matter resulted in a flurry of articles in the popular
press. I discuss this history, as well as Richard A. Posner's provocative
analysis and recommendations on how to deal with such scientific risks. I
conclude that better communication between scientists and nonscientists would
serve to assuage unreasonable fears and focus attention on truly serious
potential threats to humankind.


title: Tachyon condensation and quark mass in modified Sakai-Sugimoto model

abstract:
  This paper continues the investigation of the modified Sakai-Sugimoto model
proposed in arXiv:0708.3233. Here we discuss in detail numerical solutions to
the classical equations for the brane profile and the tachyon condensate. An
ultraviolet cut-off turns out to be essential because the numerical solutions
tend to rapidly diverge from the desired asymptotic solutions, beyond a
sufficiently large value of the holographic coordinate. The required cut-off is
determined by the non-normalizable part of the tachyon and is parametrically
far smaller than that dictated by consistency of a description in terms of
10-dimensional bulk gravity. In arXiv:0708.3233 we had argued that the solution
in which the tachyon field goes to infinity at the point where the brane and
antibrane meet has only one free parameter, which may be taken to be the
asymptotic brane-antibrane separation. Here we present numerical evidence in
favour of this observation. We also present evidence that the non-normalizable
part of the asymptotic tachyon solution, which is identified with quark mass in
the QCD-like boundary theory, is determined by this parameter. We show that the
normalizable part of the asymptotic tachyon solution determines the quark
condensate, but this requires holographic renormalization of the on-shell
boundary brane action because of the presence of infinite cut-off dependent
terms. Our renormalization scheme gives an exponential dependence on the
cut-off to the quark mass. We also discuss meson spectra in detail and show
that the pion mass is nonzero and satisfies the Gell-Mann-Oakes-Renner relation
when a small quark mass is switched on.


title: Solving Time of Least Square Systems in Sigma-Pi Unit Networks

abstract:
  The solving of least square systems is a useful operation in
neurocomputational modeling of learning, pattern matching, and pattern
recognition. In these last two cases, the solution must be obtained on-line,
thus the time required to solve a system in a plausible neural architecture is
critical. This paper presents a recurrent network of Sigma-Pi neurons, whose
solving time increases at most like the logarithm of the system size, and of
its condition number, which provides plausible computation times for biological
systems.


title: Fast Computation of Moore-Penrose Inverse Matrices

abstract:
  Many neural learning algorithms require to solve large least square systems
in order to obtain synaptic weights. Moore-Penrose inverse matrices allow for
solving such systems, even with rank deficiency, and they provide minimum-norm
vectors of synaptic weights, which contribute to the regularization of the
input-output mapping. It is thus of interest to develop fast and accurate
algorithms for computing Moore-Penrose inverse matrices. In this paper, an
algorithm based on a full rank Cholesky factorization is proposed. The
resulting pseudoinverse matrices are similar to those provided by other
algorithms. However the computation time is substantially shorter, particularly
for large systems.


title: Phase diagram of the t-U-J1-J2 chain at half filling

abstract:
  We investigate the half-filled Hubbard chain with additional nearest- and
next-nearest-neighbor spin exchange, J1 and J2, using bosonization and the
density-matrix renormalization group. For J2 = 0 we find a spin-density-wave
phase for all positive values of the Hubbard interaction U and the Heisenberg
exchange J1. A frustrating spin exchange J2 induces a bond-order-wave phase.
For some values of J1, J2 and U, we observe a spin-gapped metallic Luther-Emery
phase.


title: Intrinsic pseudo-volume forms for logarithmic pairs

abstract:
  We study an adaptation to the logarithmic case of the Kobayashi-Eisenman
pseudo-volume form, or rather an adaptation of its variant defined by Claire
Voisin, for which she replaces holomorphic maps by holomorphic
K-correspondences. We define an intrinsic logarithmic pseudo-volume form
\Phi_{X,D} for every pair (X,D) consisting of a complex manifold X and a normal
crossing Weil divisor, the positive part of which is reduced. We then prove
that \Phi_{X,D} is generically non-degenerate when X is projective and K_X+D is
ample. This result is analogous to the classical Kobayashi-Ochiai theorem. We
also show the vanishing of \Phi_{X,D} for a large class of log-K-trivial pairs,
which is an important step in the direction of the Kobayashi conjecture about
infinitesimal measure hyperbolicity in the logarithmic case.


title: Stability of Metallic Structure in Compressed Solid GeH4

abstract:
  We study the electronic and lattice dynamical properties of compressed solid
germane in the pressure range up to 200 GPa with density functional theory. A
stable metallic structure, Aba2, with a base-centered orthorhombic symmetry was
found to be the lowest enthalpy phase for pressure from 23 to 177 GPa,
suggesting an insulator to metal phase transition around 23 GPa. The Aba2
structure is predicted to have higher superconducting transition temperature
than SiH4 reported recently, thus presenting new possibilities for exploring
high temperature superconductivity in this hydrogen-rich system.


title: Muon pair creation from positronium in a linearly polarized laser field

abstract:
  Positronium decay into a muon-antimuon pair by virtue of the interaction with
a superintense laser field of linear polarization is considered. The minimum
laser intensity required amounts to a few 10^22 W/cm^2 in the near-infrared
frequency range. Within the framework of laser-dressed quantum electrodynamics,
the total reaction rate is calculated and related to the cross section for
field-free electron-positron annihilation into muons. The muons are created
with ultrarelativistic energies and emitted under narrow angles along the laser
propagation direction. The dynamical properties of the muons are interpreted in
terms of a classical simple man's model for the production process. We show
that the most promising setup for an experimental investigation of the process
employs two counterpropagating laser beams impinging on a positronium target,
where the advantage of the coherent electron-positron collisions becomes
evident.


title: The spectrum of the random environment and localization of noise

abstract:
  We consider random walk on a mildly random environment on finite transitive
d- regular graphs of increasing girth. After scaling and centering, the
analytic spectrum of the transition matrix converges in distribution to a
Gaussian noise. An interesting phenomenon occurs at d = 2: as the limit graph
changes from a regular tree to the integers, the noise becomes localized.


title: Tight local approximation results for max-min linear programs

abstract:
  In a bipartite max-min LP, we are given a bipartite graph $\myG = (V \cup I
\cup K, E)$, where each agent $v \in V$ is adjacent to exactly one constraint
$i \in I$ and exactly one objective $k \in K$. Each agent $v$ controls a
variable $x_v$. For each $i \in I$ we have a nonnegative linear constraint on
the variables of adjacent agents. For each $k \in K$ we have a nonnegative
linear objective function of the variables of adjacent agents. The task is to
maximise the minimum of the objective functions. We study local algorithms
where each agent $v$ must choose $x_v$ based on input within its
constant-radius neighbourhood in $\myG$. We show that for every $\epsilon>0$
there exists a local algorithm achieving the approximation ratio ${\Delta_I (1
- 1/\Delta_K)} + \epsilon$. We also show that this result is the best possible
-- no local algorithm can achieve the approximation ratio ${\Delta_I (1 -
1/\Delta_K)}$. Here $\Delta_I$ is the maximum degree of a vertex $i \in I$, and
$\Delta_K$ is the maximum degree of a vertex $k \in K$. As a methodological
contribution, we introduce the technique of graph unfolding for the design of
local approximation algorithms.


title:
A geometric algorithm for efficient coincident detection of
  gravitational waves

abstract:
  Data from a network of gravitational wave detectors can be analyzed in
coincidence to increase detection confidence and reduce non-stationarity of the
background. We propose and explore a geometric algorithm to combine the data
from a network of detectors. The algorithm makes optimal use of the variances
and covariances that exist amongst the different parameters of a signal in a
coincident detection of events. The new algorithm essentially associates with
each trigger ellipsoidal regions in parameter space defined by the covariance
matrix. Triggers from different detectors are deemed to be in coincidence if
their ellipsoids have a non-zero overlap. Compared to an algorithm that uses
uncorrelated windows separately for each of the signal parameters, the new
algorithm greatly reduces the background rate thereby increasing detection
efficiency at a given false alarm rate.


title: QCD sum rules study of the $J^{PC}=1^{--}$ charmonium $Y$ mesons

abstract:
  We use QCD sum rules to test the nature of the recently observed mesons
Y(4260), Y(4350) and Y(4660), assumed to be exotic four-quark
$(c\bar{c}q\bar{q})$ or $(c\bar{c}s\bar{s})$ states with $J^{PC}=1^{--}$. We
work at leading order in $\alpha_s$, consider the contributions of higher
dimension condensates and keep terms which are linear in the strange quark mass
$m_s$. We find for the $(c\bar{c}s\bar{s})$ state a mass $m_Y=(4.65\pm 0.10)$
GeV which is compatible with the experimental candidate Y(4660), while for the
$(c\bar{c}q\bar{q})$ state we find a mass $m_Y=(4.49\pm 0.11)$ GeV, which is
higger than the mass of the experimental candidate Y(4350). With the tetraquark
structure we are working we can not explain the Y(4260) as a tetraquark state.
We also consider molecular $D_{s0}\bar{D}_s^*$ and $D_{0}\bar{D}^*$ states. For
the $D_{s0}\bar{D}_s^*$ molecular state we get $m_{D_{s0}\bar{D}_s^*}=(4.42\pm
0.10)$ GeV which is consistent, considering the errors, with the mass of the
meson Y(4350) and for the $D_{0}\bar{D}^*$ molecular state we get
$m_{D_{0}\bar{D}^*}=(4.27\pm 0.10)$ GeV in excelent agreement with the mass of
the meson Y(4260).


title: Relevant First-Order Logic $LP^\#$ and Curry's Paradox resolution

abstract:
  In 1942 Haskell B.Curry presented what is now called Curry paradox which can
be found in a logic independently of its stand on negation.In recent years
there has been a revitalised interest in non-classical solutions to the
semantic paradoxes. In this article the non-classical resolution of Curry's
Paradox and Shaw-Kwei paradox without rejection any contraction postulate is
proposed.


title: The Minimum Backlog Problem

abstract:
  We study the minimum backlog problem (MBP). This online problem arises, e.g.,
in the context of sensor networks. We focus on two main variants of MBP.
  The discrete MBP is a 2-person game played on a graph $G=(V,E)$. The player
is initially located at a vertex of the graph. In each time step, the adversary
pours a total of one unit of water into cups that are located on the vertices
of the graph, arbitrarily distributing the water among the cups. The player
then moves from her current vertex to an adjacent vertex and empties the cup at
that vertex. The player's objective is to minimize the backlog, i.e., the
maximum amount of water in any cup at any time.
  The geometric MBP is a continuous-time version of the MBP: the cups are
points in the two-dimensional plane, the adversary pours water continuously at
a constant rate, and the player moves in the plane with unit speed. Again, the
player's objective is to minimize the backlog.
  We show that the competitive ratio of any algorithm for the MBP has a lower
bound of $\Omega(D)$, where $D$ is the diameter of the graph (for the discrete
MBP) or the diameter of the point set (for the geometric MBP). Therefore we
focus on determining a strategy for the player that guarantees a uniform upper
bound on the absolute value of the backlog.
  For the absolute value of the backlog there is a trivial lower bound of
$\Omega(D)$, and the deamortization analysis of Dietz and Sleator gives an
upper bound of $O(D\log N)$ for $N$ cups. Our main result is a tight upper
bound for the geometric MBP: we show that there is a strategy for the player
that guarantees a backlog of $O(D)$, independently of the number of cups.


title:
Thermal entanglement in the anisotropic Heisenberg XXZ model with the
  Dzyaloshinskii-Moriya interaction

abstract:
  The thermal entanglement is investigated in a two-qubit Heisenberg XXZ system
with Dzyaloshinskii-Moriya (DM) interaction. It is shown that the entanglement
can be efficiently controlled by the DM interaction parameter and coupling
coefficient $J_{z}$. $D_{x}$(the x-component parameter of the DM interaction)
has a more remarkable influence on the entanglement and the critical
temperature than $D_{z}$(the z-component parameter of the DM interaction).
Thus, by the change of DM interaction direction, we can get a more efficient
control parameter to increase the entanglement and the critical temperature.


title: Relativistic Universe Scenario

abstract:
  The luminocity-distance -- redshift SN Ia data and the Cosmic Microwave
Background power spectrum are discussed in the context of the results and ideas
of the eminent Russian physicist-theorist N.A. Chernikov. His results include
the Boltzmann-Chernikov distribution in the kinetic theory of relativistic gas,
conformal invariant theory of scalar field, and the vacuum cosmological
creation of particles. We use these results for explanation of the origin of
matter content of the Universe in the modern relativistic physics.


title:
Optical control of non-equilibrium superconducting phase transition
  below Tc in a cuprate

abstract:
  Photoinduced phase transitions from insulating to metallic states,
accompanied by structural re-arrangements, have been recently reported in
complex transition-metal oxides. However, the optical control of a purely
electronic phase transition, where the thermodynamic phase is determined by the
distribution of excitations, has remained elusive. Here we report optical
control of the electronic phase in an underdoped Bi2212 crystal through
impulsive photoinjection of quasiparticles (QP) via ultrashort laser pulses,
avoiding significant laser heating. An abrupt transition of the transient
optical electronic response is observed at a critical fluence of Ipump=70
uJ/cm^2. We show that the measured dynamics is consistent with an inhomogenous
first-order superconducting-to-normal state phase transition, triggered by a
sudden shift of the chemical potential.


title: On Einstein Metrics on 4-Manifolds with Finite Cyclic Fundamental Group

abstract:
  The existence or non-existence of Einstein metrics on 4-manifolds with
non-trivial fundamental group and the relation with the underlying differential
structure are analyzed. For most points $(n,m)$ in a large region of the
integer lattice, the manifold $n\mathbb C \mathbb P^2\#m \overline{\mathbb C
\mathbb P^2}$ is shown to admit infinitely many inequivalent free actions of
finite cyclic groups and there are no Einstein metrics which are invariant
under any of these actions. The main tools are Seiberg-Witten theory, cyclic
branched coverings of complex surfaces and symplectic surgeries.


title: Motivic renormalization and singularities

abstract:
  We consider parametric Feynman integrals and their dimensional regularization
from the point of view of differential forms on hypersurface complements and
the approach to mixed Hodge structures via oscillatory integrals. We consider
restrictions to linear subspaces that slice the singular locus, to handle the
presence of non-isolated singularities. In order to account for all possible
choices of slicing, we encode this extra datum as an enrichment of the Hopf
algebra of Feynman graphs. We introduce a new regularization method for
parametric Feynman integrals, which is based on Leray coboundaries and, like
dimensional regularization, replaces a divergent integral with a Laurent series
in a complex parameter. The Connes--Kreimer formulation of renormalization can
be applied to this regularization method. We relate the dimensional
regularization of the Feynman integral to the Mellin transforms of certain
Gelfand--Leray forms and we show that, upon varying the external momenta, the
Feynman integrals for a given graph span a family of subspaces in the
cohomological Milnor fibration. We show how to pass from regular singular
Picard--Fuchs equations to irregular singular flat equisingular connections. In
the last section, which is more speculative in nature, we propose a geometric
model for dimensional regularization in terms of logarithmic motives and
motivic sheaves.


title: Measurements of heavy quark production via single leptons at PHENIX

abstract:
  The measurement of single leptons from the semi-leptonic decay of
heavy-flavor hadrons has long been a means for studying heavy-quark production.
PHENIX has measured single muons in pp collisions at forward rapidity and
single electrons in both pp and AuAu collisions at mid-rapidity at
sqrt(s_NN)=200 GeV. The most recent PHENIX single lepton results are presented
in the context of state-of-the-art pQCD calculations. An updated azimuthal
anisotropy, v2(pT), measurement for heavy-flavor single electrons in AuAu
collisions is also presented.


title:
Finite size effects in the Gross-Neveu model with isospin chemical
  potential

abstract:
  The properties of the two-flavored Gross-Neveu model in the (1+1)-dimensional
$R^1\times S^1$ spacetime with compactified space coordinate are investigated
in the presence of the isospin chemical potential $\mu_I$. The consideration is
performed in the limit $N_c\to\infty$, i.e. in the case with infinite number of
colored quarks. It is shown that at $L=\infty$ ($L$ is the length of the
circumference $S^1$) the pion condensation phase is realized for arbitrary
small nonzero $\mu_I$. At finite values of $L$, the phase portraits of the
model in terms of parameters $\nu\sim\mu_I$ and $\lambda\sim 1/L$ are obtained
both for periodic and antiperiodic boundary conditions of the quark field. It
turns out that in the plane $(\lambda,\nu)$ there is a strip
$0\le\lambda<\lambda_c$ which lies as a whole inside the pion condensed phase.
In this phase the pion condensation gap is an oscillating function vs both
$\lambda$ (at fixed $\nu$) and $\nu$ (at fixed $\lambda$).


title:
Charge amplification concepts for direction-sensitive dark matter
  detectors

abstract:
  Direction measurement of weakly interacting massive particles in
time-projection chambers can provide definite evidence of their existence and
help to determine their properties. This article demonstrates several concepts
for charge amplification in time-projection chambers that can be used in
direction-sensitive dark matter search experiments. We demonstrate
reconstruction of the 'head-tail' effect for nuclear recoils above 100keV, and
discuss the detector performance in the context of dark matter detection and
scaling to large detector volumes.


title: Chemical Gas Sensors Based On Nanowires

abstract:
  Chemical gas sensors based on nanowires can find a wide range of applications
in clinical assaying, environmental emission control, explosive detection,
agricultural storage and shipping, and workplace hazard monitoring. Sensors in
the forms of nanowires are expected to have significantly enhanced performance
due to high surface-volume ratio and quasi-one-dimensional confinement in
nanowires. Indeed, chemical gas sensors based on nanowires with a ppb level
sensitivity have been demonstrated. In this review, the fundamental aspects on
(i) methods of nanowire synthesis (ii) performance of nanowire sensors, (iii)
chemiresistors, transistor sensors, and their sensing mechanism, and (iv)
assembly technologies will be summarized and discussed. The prospects of the
future research on chemical gas sensors based on nanowires will be also
addressed.


title: Logarithmic Fourier integrals for the Riemann Zeta Function

abstract:
  We use symmetric Poisson-Schwarz formulas for analytic functions $f$ in the
half-plane ${Re}(s)>\frac12$ with $\bar{f(\bar{s})}=f(s)$ in order to derive
factorisation theorems for the Riemann zeta function. We prove a variant of the
Balazard-Saias-Yor theorem and obtain explicit formulas for functions which are
important for the distribution of prime numbers. In contrast to Riemann's
classical explicit formula, these representations use integrals along the
critical line ${Re}(s)=\frac12$ and Blaschke zeta zeroes.


title:
Sparse Spike Coding : applications of Neuroscience to the processing of
  natural images

abstract:
  If modern computers are sometimes superior to humans in some specialized
tasks such as playing chess or browsing a large database, they can't beat the
efficiency of biological vision for such simple tasks as recognizing and
following an object in a complex cluttered background. We present in this paper
our attempt at outlining the dynamical, parallel and event-based representation
for vision in the architecture of the central nervous system. We will
illustrate this on static natural images by showing that in a signal matching
framework, a L/LN (linear/non-linear) cascade may efficiently transform a
sensory signal into a neural spiking signal and we will apply this framework to
a model retina. However, this code gets redundant when using an over-complete
basis as is necessary for modeling the primary visual cortex: we therefore
optimize the efficiency cost by increasing the sparseness of the code. This is
implemented by propagating and canceling redundant information using lateral
interactions. We compare the efficiency of this representation in terms of
compression as the reconstruction quality as a function of the coding length.
This will correspond to a modification of the Matching Pursuit algorithm where
the ArgMax function is optimized for competition, or Competition Optimized
Matching Pursuit (COMP). We will in particular focus on bridging neuroscience
and image processing and on the advantages of such an interdisciplinary
approach.


title: Global properties of the HI distribution in the outer Milky Way

abstract:
  Aims: We derive the 3-D HI volume density distribution for the Galactic disk
out to R = 60 kpc. Methods: Our analysis is based on parameters for the warp
and rotation curve derived previously. The data are taken from the
Leiden/Argentine/Bonn all sky 21-cm line survey. Results: The Milky Way HI disk
is significantly warped but shows a coherent structure out to R = 35 kpc. The
radial surface density distribution, the densities in the middle of the warped
plane, and the HI scale heights all follow exponential relations. The radial
scale length for the surface density distribution of the HI disk is 3.75 kpc.
Gas at the outskirts for 40 < R < 60 kpc is described best by a distribution
with an exponential radial scale length of 7.5 kpc and a velocity dispersion of
74 km/s. Such a highly turbulent medium fits also well with the average shape
of the high velocity profile wings observed at high latitudes. The turbulent
pressure gradient of such extra-planar gas is on average in balance with the
gravitational forces. About 10% of the Milky Way HI gas is in this state. The
large scale HI distribution is lopsided; for R < 15 kpc there is more gas in
the south. The HI flaring indicates that this asymmetry is caused by a dark
matter wake, located at R = 25 kpc in direction of the Magellanic System.
Conclusions: The HI disk is made up of two major components. Most prominent is
the normal HI disk which can be traced to R = 35 kpc. This is surrounded by a
patchy distribution of highly turbulent gas reaching large scale heights but
also large radial distances. At the position of the Sun the exponential scale
height in the z direction is 3.9 kpc. This component resembles the anomalous
gas discovered previously in some galaxies.


title:
Phase and amplitude response of "0.7 feature" caused by holes in silicon
  one-dimensional wires and rings

abstract:
  We present the findings of the 0.7(2e2/h) feature in the hole quantum
conductance staircase that is caused by silicon one-dimensional channels
prepared by the split-gate method inside the p-type silicon quantum well (SQW)
on the n-type Si (100) surface. Firstly, the interplay of the spin
depolarisation with the evolution of the 0.7(2e2/h) feature from the e2/h to
3/2 e2/h values as a function of the sheet density of holes is revealed by the
quantum point contact connecting two 2D reservoirs in the p-type SQW. The 1D
holes are demonstrated to be spin-polarised at low sheet density, because the
0.7(2e2/h) feature is close to the value of 0.5(2e2/h) that indicates the spin
degeneracy lifting for the first step of the quantum conductance staircase. The
0.7(2e2/h) feature is found to take however the value of 0.75(2e2/h) when the
sheet density increases thereby giving rise to the spin depolarisation of the
1D holes. Secondly, the amplitude and phase sensitivity of the 0.7(2e2/h)
feature are studied by varying the value of the external magnetic field and the
top gate voltage that are applied perpendicularly to the plane of the
double-slit ring embedded in the p-type SQW, with the extra quantum point
contact inserted in the one of its arms. The Aharonov-Bohm (AB) and the
Aharonov-Casher (AC) conductance oscillations obtained are evidence of the
interplay of the spontaneous spin polarisation and the Rashba spin-orbit
interaction (SOI) in the formation of the 0.7(2e2/h) feature. Finally, the
variations of the 0.7(2e2/h) feature caused by the Rashba SOI are found to take
in the fractional form with both the plateaux and steps as a function of the
top gate voltage.


title: Diffusion and localization in carbon nanotubes and graphene nanoribbons

abstract:
  We study transport length scales in carbon nanotubes and graphene ribbons
under the influence of Anderson disorder. We present generalized analytical
expressions for the density of states, the elastic mean free path and the
localization length in arbitrarily structured quantum wires. These allow us to
analyze the electrical response over the full energy range, including the
regions around van Hove singularies, traditionally difficult to access by
alternative approaches. Comparing with the results of numerical simulations, we
demonstrate that both the diffusive and the localized regime are well
represented by the analytical approximations over a wide range of the energy
spectrum. The approach works well for both metallic and semiconducting
nanotubes and nanoribbons but breaks down near the edge states of zigzag
ribbons.


title:
Energetic and Entropic Analysis of Mirror Symmetry Breaking Processes in
  a Recycled Microreversible Chemical System

abstract:
  Understanding how biological homochirality emerged remains a challenge for
the researchers interested in the origin of life. During the last decades,
stable non-racemic steady states of nonequilibrium chemical systems have been
discussed as a possible response to this problem. In line with this framework,
a description of recycled systems was provided in which stable products can be
activated back to reactive compounds. The dynamical behaviour of such systems
relies on the presence of a source of energy, leading to the continuous
maintaining of unidirectional reaction loops. A full thermodynamic study of
recycled systems, composed of microreversible reactions only, is presented
here, showing how the energy is transferred and distributed through the system,
leading to cycle competitions and the stabilization of asymmetric states.


title: Multiplicative Bundle Gerbes with Connection

abstract:
  Multiplicative bundle gerbes are gerbes over a Lie group which are compatible
with the group structure. In this article connections on such bundle gerbes are
introduced and studied. It is shown that multiplicative bundle gerbes with
connection furnish geometrical constructions of the following objects: smooth
central extensions of loop groups, Chern-Simons actions for arbitrary gauge
groups, and symmetric bi-branes for WZW models with topological defect lines.


title: String Dual of N=1 Super Yang-Mills on the Cylinder

abstract:
  We study the stringy description of N=1 supersymmetric SU(N) gauge theory on
R^{1,2}xS^1. Our description is based on the known Maldacena-Nunez solution,
properly modified to account for the compact dimension. The most interesting of
its properties is that extra BPS M-branes are present, which generate a
non-perturbative superpotential that we explicitly compute.


title: Computation of Selberg zeta functions on Hecke triangle groups

abstract:
  In this paper, a heuristic method to compute the Selberg zeta function for
Hecke triangle groups, $G_q$ ($q>=3$) is described. The algorithm is based on
the transfer operator method and an overview of the relevant background is
given. We give numerical support for the claim that the method works and can be
used to compute the Selberg Zeta function for $G_q$ to any desired precision.
We also present some numerical results obtained by implementing the algorithm.


title:
The screening of the 11.3 micron SiC feature by carbonaceous mantles in
  circumstellar shells

abstract:
  Silicon carbide, a refractory material, condenses near the photospheres of
C-rich AGB stars, giving rise to a conspicuous emission feature at 11.3 mu. In
the presence of a stellar wind, the SiC grains are carried outwards to colder
regions, where less refractory carbonaceous material can condense, either by
itself or in mantles upon SiC grains. Enough carbon can condense on the latter
that their specific feature is completely veiled. Thus may be explained a) the
coexistence of the SiC feature protruding above a carbonaceous continuum, with
a range of contrasts, corresponding to various volume ratios of mantle to core;
b) the ultimate disappearance of the 11.3-$\mu$m feature from the interstellar
medium, where the mantle has become completely opaque due to the much higher
cosmic abundance of carbon.


title: Ground state study of simple atoms within a nano-scale box

abstract:
  Ground state energies for confined hydrogen (H) and helium (He) atoms, inside
a penetrable/impenetrable compartment have been calculated using Diffusion
Monte Carlo (DMC) method. Specifically, we have investigated spherical and
ellipsoidal encompassing compartments of a few nanometer size. The potential is
held fixed at a constant value on the surface of the compartment and beyond.
The dependence of ground state energy on the geometrical characteristics of the
compartment as well as the potential value on its surface has been thoroughly
explored. In addition, we have investigated the cases where the nucleus
location is off the geometrical centre of the compartment.


title: Biased quasi ballistic spin torque magnetization reversal

abstract:
  We explore the fundamental time limit of ultra fast spin torque induced
magnetization reversal of a magnetic memory cell. Spin torque precession during
a spin torque current pulse and free precessional magnetization ringing after
spin torque pulse excitation is detected by time resolved magneto transport.
Adapting the duration of the spin torque excitation pulse to the spin torque
precession period allows suppression of the magnetization ringing and thus
coherent control of the final orientation of the magnetization. In the presence
of a hard axis bias field such coherent control enables an optimum ultra fast,
quasi ballistic spin torque magnetization reversal by a single precessional
turn directly from the initial to the reversed equilibrium state.


title: Quasi-free photoproduction of eta-mesons of the neutron

abstract:
  Quasi-free photoproduction of eta-mesons off nucleons bound in the deuteron
has been measured with the CBELSA/TAPS detector for incident photon energies up
to 2.5 GeV at the Bonn ELSA accelerator. The eta-mesons have been detected in
coincidence with recoil protons and recoil neutrons, which allows a detailed
comparison of the quasi-free n(gamma,eta)n and p(gamma,eta)p reactions. The
excitation function for eta-production off the neutron shows a pronounced
bump-like structure at W=1.68 GeV (E_g ~ 1 GeV), which is absent for the
proton.


title:
On the Index and the Order of Quasi-regular Implicit Systems of
  Differential Equations

abstract:
  This paper is mainly devoted to the study of the differentiation index and
the order for quasi-regular implicit ordinary differential algebraic equation
(DAE) systems. We give an algebraic definition of the differentiation index and
prove a Jacobi-type upper bound for the sum of the order and the
differentiation index. Our techniques also enable us to obtain an alternative
proof of a combinatorial bound proposed by Jacobi for the order.
  As a consequence of our approach we deduce an upper bound for the
Hilbert-Kolchin regularity and an effective ideal membership test for
quasi-regular implicit systems. Finally, we prove a theorem of existence and
uniqueness of solutions for implicit differential systems.


title: Families of prudent self-avoiding walks

abstract:
  A self-avoiding walk (SAW) on the square lattice is prudent if it never takes
a step towards a vertex it has already visited. Prudent walks differ from most
classes of SAW that have been counted so far in that they can wind around their
starting point. Their enumeration was first addressed by Pr\'ea in 1997. He
defined 4 classes of prudent walks, of increasing generality, and wrote a
system of recurrence relations for each of them . However, these relations
involve more and more parameters as the generality of the class increases. The
first class actually consists of partially directed walks, and its generating
function is well-known to be rational. The second class was proved to have an
algebraic (quadratic) generating function by Duchi (2005). Here, we solve
exactly the third class, which turns out to be much more complex: its
generating function is not algebraic, nor even D-finite. The fourth class --
general prudent walks -- is the only isotropic one, and still defeats us.
However, we design an isotropic family of prudent walks on the triangular
lattice, which we count exactly. Again, the generating function is proved to be
non-D-finite. We also study the asymptotic properties of these classes of
walks, with the (somewhat disappointing) conclusion that their endpoint moves
away from the origin at a positive speed. This is confirmed visually by the
random generation procedures we have designed.


title:
Polarization preserving ultra fast optical shutter for quantum
  information processing

abstract:
  We present the realization of a ultra fast shutter for optical fields, which
allows to preserve a generic polarization state, based on a self-stabilized
interferometer. It exhibits high (or low) transmittivity when turned on (or
inactive), while the fidelity of the polarization state is high. The shutter is
realized through two beam displacing prisms and a longitudinal Pockels cell.
This can represent a useful tool for controlling light-atom interfaces in
quantum information processing.


title:
The effect of a nonresonant radiative field on low-energy rotationally
  inelastic $\text{Na}^{+} + \text{N}_2$ collisions

abstract:
  We examine the effects of a linearly polarized nonresonant radiative field on
the dynamics of rotationally inelastic $\text{Na}^{+} + \text{N}_2$ collisions
at eV collision energies. Our treatment is based on the Fraunhofer model of
matter wave scattering and its recent extension to collisions in electric
fields [arXiv:0804.3318v1]. The nonresonant radiative field changes the
effective shape of the target molecule by aligning it in the space-fixed frame.
This markedly alters the differential and integral scattering cross sections.
As the cross sections can be evaluated for a polarization of the radiative
field collinear or perpendicular to the relative velocity vector, the model
also offers predictions about steric asymmetry of the collisions.


title: J/psi production at high pT in p+p and A+A collisions at STAR

abstract:
  The preliminary results of J/psi spectra at high transverse momentum
(5<p_T<14 GeV/c) in p+p and Cu+Cu collisions at s_NN = 200 GeV are reported.
The nuclear modification factor is measured to be 0.9+/-0.2 at p_T>5 GeV/c. The
correlations between J/psi and charged hadrons are also studied in p+p
collisions to understand the J/psi production mechanism at high p_T.


title: A combinatorial proof of the Removal Lemma for Groups

abstract:
  Green [Geometric and Functional Analysis 15 (2005), 340--376] established a
version of the Szemer\'edi Regularity Lemma for abelian groups and derived the
Removal Lemma for abelian groups as its corollary. We provide another proof of
his Removal Lemma that allows us to extend its statement to all finite groups.
We also discuss possible extensions of the Removal Lemma to systems of
equations.


title: Theory of the Elementary Particles

abstract:
  Lattice theory is used to explain the rest masses of the stable mesons and
baryons and their spin. From the mass of the charged pi-mesons follows the mass
of the muons. From the mass of the muons follows the mass of the electron. We
do not use hypothetical particles. Only photons, neutrinos and charge are
needed to explain the mass of the elementary particles.


title: Macroscopic observables and the Born rule

abstract:
  We clarify the role of the Born rule in the Copenhagen Interpretation of
quantum mechanics by deriving it from Bohr's doctrine of classical concepts,
translated into the following mathematical statement: a quantum system
described by a noncommutative C*-algebra of observables is empirically
accessible only through associated commutative C*-algebras. The Born
probabilities emerge as the relative frequencies of outcomes in long runs of
measurements on a quantum system; it is not necessary to adopt the frequency
interpretation of single-case probabilities (which will be the subject of a
sequel paper). Our derivation of the Born rule uses ideas from a program begun
by Finkelstein (1965) and Hartle (1968), intending to remove the Born rule as a
separate postulate of quantum mechanics. Mathematically speaking, our approach
refines previous elaborations of this program - notably the one due to Farhi,
Goldstone, and Gutmann (1989) as completed by Van Wesep (2006) - in replacing
infinite tensor products of Hilbert spaces by continuous fields of C*-algebras.
In combination with our interpretational context, this technical improvement
circumvents valid criticisms that earlier derivations of the Born rule have
provoked, especially to the effect that such derivations were mathematically
flawed as well as circular. Furthermore, instead of relying on the
controversial eigenvector-eigenvalue link in quantum theory, our derivation
just assumes that pure states in classical physics have the usual
interpretation as truthmakers that assign sharp values to observables.


title:
Driver Choice Compared to Controlled Diversion for a Freeway Double
  On-Ramp

abstract:
  Two diversion schemes that apportion demand between two on-ramps to reduce
congestion and improve throughput on a freeway are analyzed. In the first
scheme, drivers choose to merge or to divert to a downstream on-ramp based on
information about average travel times for the two routes: (1) merge and travel
on the freeway or (2) divert and travel on a surface street with merging
downstream. The flow, rate of merging at the ramps, and the travel times
oscillate strongly, but irregularly, due to delayed feedback. In the second
scheme, diversion is controlled by the average mainline velocities just
upstream of the on-ramps. Driver choice is not involved. If the average
upstream velocity on the mainline drops below a predetermined value (20 m/s)
vehicles are diverted to the downstream ramp. When the average mainline
velocity downstream becomes too low, diversion is no longer permitted. The
resultant oscillations in this scheme are nearly periodic. The period is
dominated by the response time of the mainline to interruption of merging
rather than delayed feedback, which contributes only a minor component linear
in the distance separating the on-ramps. In general the second scheme produces
more effective congestion reduction and greater throughput. Also the travel
times for on-ramp drivers are less than that obtained by drivers who attempt to
minimize their own travel times (first scheme).


title:
On the Possibility of Development of the Explosion Instability in a
  Two-Component Gravitating System

abstract:
  We obtain an expression for the energy of the density wave propagating in a
multicomponent gravitating medium in the form well known from electrodynamics.
Using the above, the possibility of "triple production" of the quasi-particles,
or waves, with their energies summing up to zero, in a non-equilibrium medium
is demonstrated. That kind of resonance wave interaction is shown to result in
the development of an explosion instability. By the method developed in plasma
physics, the characteristic time of the instability is evaluated.


title: Dynamics of Functions with an Eventual Negative Schwarzian Derivative

abstract:
  In the study of one dimensional dynamical systems one often assumes that the
functions involved have a negative Schwarzian derivative. In this paper we
consider a generalization of this condition. Specifically, we consider the
interval functions of a real variable having some iterate with a negative
Schwarzian derivative and show that many known results generalize to this
larger class of functions. The introduction of this class was motivated by some
maps arising in neuroscience.


title: Motivic Weight Complexes for Arithmetic Varieties

abstract:
  We associate weight complexes of (homological) motives, and hence Euler
characteristics in the Grothendieck group of motives, to arithmetic varieties
and Deligne-Mumford stacks; this extends the results in the paper "Descent,
Motives and K-theory" in volume 478 of Crelle, where a similar result was
proved for varieties over a field of characteristic zero. We use K_0-motives
with rational coefficients, rather than Chow motives, because we cannot appeal
to resolution of singularities, but rather must use de Jong's results. In
addition, for varieties over a field we prove a general result on
contravariance of weight complexes, in particular showing that any morphism of
finite tor-dimension between varieties induces a morphism of weight complexes.


title: Highly-symmetric travelling waves in pipe flow

abstract:
  The recent theoretical discovery of finite-amplitude travelling waves in pipe
flow has re-ignited interest in the transitional phenomena that Osborne
Reynolds studied 125 years ago. Despite all being unstable, these waves are
providing fresh insight into the flow dynamics. Here we describe two new
classes of highly-symmetric travelling waves (possessing rotational,
shift-&-reflect and mirror symmetries) and report a new family of
mirror-symmetric waves which is the first found in pipe flow not to have
shift-&-reflect symmetry. The highly-symmetric waves appear at lower Reynolds
numbers than the originally-discovered non-mirror-symmetric waves found by
Faisst & Eckhardt 2003 and Wedin & Kerswell 2004 and have much higher wall
shear stresses. The first M-class comprises of the various
discrete-rotationally-symmetric analogues of the mirror-symmetric wave found in
Pringle & Kerswell (2007) and have a distinctive double layer structure of fast
and slow streaks across the pipe radius. The second N-class has the more
familiar separation of fast streaks to the exterior and slow streaks to the
interior and looks the precursor to the class of non-mirror-symmetric waves
already known.


title:
Impact of the electrical connection of N Spin Transfer Oscillators on
  their synchronization : an analytical study

abstract:
  Spin Transfer Nano-Oscillators (STNOs) are good candidates for applications
to telecommunications, but their output power is very low, under the nW. A
possible solution to overcome this problem is to synchronize an assembly of
STNOs. For manufacturing purposes, large number of STNOs will have to be
electrically connected. In this letter, we study analytically the impact of
electrical connection on the synchronization of STNOs. Our analysis shows that
the phase dynamics of the coupled STNOs can be described in the framework of
the Kuramoto model. The conditions for successful synchronization of an
assembly of STNOs are derived.


title: Arithmetic partial differential equations, II: modular curves

abstract:
  We classify ``arithmetic convection equations'' on modular curves, and
describe their space of solutions. Certain of these solutions involve the
Fourier expansions of the Eisenstein modular forms of weight 4 and 6, while
others involve the Serre-Tate expansions of the same modular forms; in this
sense, our arithmetic convection equations can be seen as "unifying" the two
types of expansions. The theory can be generalized to one of
  ``arithmetic heat equations'' on modular curves, but we prove that modular
curves do not carry ``arithmetic wave equations.'' Finally, we prove an
instability result for families of arithmetic heat equations converging to an
arithmetic convection equation.


title: Neutrino Oscillation Parameters After High Statistics KamLAND Results

abstract:
  We do a re-analysis to asses the impact of the results of the Borexino
experiment and the recent 2.8 KTy KamLAND data on the solar neutrino
oscillation parameters. The current Borexino results are found to have no
impact on the allowed solar neutrino parameter space. The new KamLAND data
causes a significant reduction of the allowed range of $\Delta m^2_{21}$,
determining it with an unprecedented precision of 8.3% at 3$\sigma$. The
precision of $\Delta m^2_{21}$ is controlled practically by the KamLAND data
alone. Inclusion of new KamLAND results also improves the upper bound on
$\sin^2\theta_{12}$, but the precision of this parameter continues to be
controlled by the solar data. The third mixing angle is constrained to be
$\sin^2\theta_{13} < 0.063$ at $3\sigma$ from a combined fit to the solar,
KamLAND, atmospheric and CHOOZ results. We also address the issue of how much
further reduction of allowed range of $\Delta m^2_{21}$ and $\sin^2\theta_{12}$
is possible with increased statistics from KamLAND. We find that there is a
sharp reduction of the $3\sigma$ ``spread'' with enhanced statistics till about
10 KTy after which the spread tends to flatten out reaching to less than 4%
with 15 KTy data. For $\sin^2\theta_{12}$ however, the spread is more than 25%
even after 20 KTy exposure and assuming $\theta_{12} < \pi/4$, as dictated by
the solar data. We show that with a KamLAND like reactor ``SPMIN'' experiment
at a distance of $\sim$ 60 km, the spread of $\sin^2\theta_{12}$ could be
reduced to about 5% at $3\sigma$ level while $\Delta m_{21}^2$ could be
determined to within 4%, with just 3 KTy exposure.


title: Closedness of the tangent spaces to the orbits of proper actions

abstract:
  In this note we show that for any proper action of a Banach--Lie group $G$ on
a Banach manifold $M$, the corresponding tangent maps $\g \to T_x(M)$ have
closed range for each $x \in M$, i.e., the tangent spaces of the orbits are
closed. As a consequence, for each free proper action on a Hilbert manifold,
the quotient $M/G$ carries a natural manifold structure.


title: The communication complexity of non-signaling distributions

abstract:
  We study a model of communication complexity that encompasses many
well-studied problems, including classical and quantum communication
complexity, the complexity of simulating distributions arising from bipartite
measurements of shared quantum states, and XOR games. In this model, Alice gets
an input x, Bob gets an input y, and their goal is to each produce an output
a,b distributed according to some pre-specified joint distribution p(a,b|x,y).
  We introduce a new technique based on affine combinations of lower-complexity
distributions. Specifically, we introduce two complexity measures, one which
gives lower bounds on classical communication, and one for quantum
communication. These measures can be expressed as convex optimization problems.
We show that the dual formulations have a striking interpretation, since they
coincide with maximum violations of Bell and Tsirelson inequalities. The dual
expressions are closely related to the winning probability of XOR games. These
lower bounds subsume many known communication complexity lower bound methods,
most notably the recent lower bounds of Linial and Shraibman for the special
case of Boolean functions.
  We show that the gap between the quantum and classical lower bounds is at
most linear in the size of the support of the distribution, and does not depend
on the size of the inputs. This translates into a bound on the gap between
maximal Bell and Tsirelson inequality violations, which was previously known
only for the case of distributions with Boolean outcomes and uniform marginals.
  Finally, we give an exponential upper bound on quantum and classical
communication complexity in the simultaneous messages model, for any
non-signaling distribution. One consequence is a simple proof that any quantum
distribution can be approximated with a constant number of bits of
communication.


title:
Synthesis of maximally entangled mixed states and disentanglement in
  coupled Josephson charge qubits

abstract:
  We analyze a controllable generation of maximally entangled mixed states of a
circuit containing two-coupled superconducting charge qubits. Each qubit is
based on a Cooper pair box connected to a reservoir electrode through a
Josephson junction. Illustrative variational calculations were performed to
demonstrate the effect on the two-qubits entanglement. At sufficiently
deviation between the Josephson energies of the qubits and/or strong coupling
regime, maximally entangled mixed states at certain instances of time is
synthesized. We show that entanglement has an interesting subsequent time
evolution, including the sudden death effect. This enables us to completely
characterize the phenomenon of entanglement sharing in the coupling of two
superconducting charge qubits, a system of both theoretical and experimental
interest.


title: Interfacing light and single atoms with a lens

abstract:
  We characterize the interaction between a single atom or similar microscopic
system and a light field via the scattering ratio. For that, we first derive
the electrical field in a strongly focused Gaussian light beam, and then
consider the atomic response. Following the simple scattering model, the
fraction of scattered optical power for a weak coherent probe field leads to
unphysical scattering ratios above 1 in the strong focusing regime. A refined
model considering interference between exciting and scattered field into
finite-sized detectors or optical fibers is presented, and compared to
experimental extinction measurements for various focusing strengths.


title:
STEREO/SECCHI Stereoscopic Observations Constraining the Initiation of
  Polar Coronal Jets

abstract:
  We report on the first stereoscopic observations of polar coronal jets made
by the EUVI/SECCHI imagers on board the twin STEREO spacecraft. The
significantly separated viewpoints ($\sim$ 11$^\circ$) allowed us to infer the
3D dynamics and morphology of a well-defined EUV coronal jet for the first
time. Triangulations of the jet's location in simultaneous image pairs led to
the true 3D position and thereby its kinematics. Initially the jet ascends
slowly at $\approx$10-20 $\mathrm{{km} {s}^{-1}}$ and then, after an apparent
'jump' takes place, it accelerates impulsively to velocities exceeding 300
$\mathrm{{km} {s}^{-1}}$ with accelerations exceeding the solar gravity.
Helical structure is the most important geometrical feature of the jet which
shows evidence of untwisting. The jet structure appears strikingly different
from each of the two STEREO viewpoints: face-on in the one viewpoint and
edge-on in the other. This provides conclusive evidence that the observed
helical structure is real and is not resulting from possible projection effects
of single viewpoint observations. The clear demonstration of twisted structure
in polar jets compares favorably with synthetic images from a recent MHD
simulation of jets invoking magnetic untwisting as their driving mechanism.
Therefore, the latter can be considered as a viable mechanism for the
initiation of polar jets.


title: Glueballs and the superfluid phase of Two-Color QCD

abstract:
  We present the first results on scalar glueballs in cold, dense matter using
lattice simulations of two color QCD. The simulations are carried out on a $6^3
\times 12$ lattice and use a standard hybrid molecular dynamics algorithm for
staggered fermions for two values of quark mass. The glueball correlators are
evaluated via a multi-step smearing procedure. The amplitude of the glueball
correlator peaks in correspondence with the zero temperature chiral transition,
$\mu_c = m_\pi/2$, and the propagators change in a significant way in the
superfluid phase, while the Polyakov loop is mearly insensitive to the
transition. Standard analysis suggest that lowest mass in the $0^{++}$ gluonic
channel decreases in the superfluid phase, but these observations need to be
confirmed on larger and more elongated lattices These results indicate that a
nonzero density induces nontrivial modifications of the gluonic medium.


title:
Measurements of high $p_{T}$ identified particles $v_{2}$ and $v_{4}$ in
  $\sqrt{s_{NN}} = 200$ GeV Au+Au collisions by PHENIX

abstract:
  The $v_{2}$ and $v_{4}$ of pions, kaons and protons have been measured by
PHENIX in 200 GeV Au+Au collisions up to $p_{T}$$\sim$6 GeV/c and 4 GeV/c,
respectively. The $v_{4}$ of all these identified particles have been found to
scale with the number of constituent quarks and all these particles have a
similar $v_{4}$/$v_{2}^{2}$ ratio which is close to 0.9. The scaling behavior
of $v_2$ is studied at high-$p_{T}$ and a deviations from the universal scaling
is observed for transverse kinetic energy ($K_{ET}/nq$) higher than 1 GeV.


title: Characterizing Video Responses in Social Networks

abstract:
  Video sharing sites, such as YouTube, use video responses to enhance the
social interactions among their users. The video response feature allows users
to interact and converse through video, by creating a video sequence that
begins with an opening video and followed by video responses from other users.
Our characterization is over 3.4 million videos and 400,000 video responses
collected from YouTube during a 7-day period. We first analyze the
characteristics of the video responses, such as popularity, duration, and
geography. We then examine the social networks that emerge from the video
response interactions.


title:
Sum-Capacity of Ergodic Fading Interference and Compound Multiaccess
  Channels

abstract:
  The problem of resource allocation is studied for two-sender two-receiver
fading Gaussian interference channels (IFCs) and compound multiaccess channels
(C-MACs). The senders in an IFC communicate with their own receiver (unicast)
while those in a C-MAC communicate with both receivers (multicast). The
instantaneous fading state between every transmit-receive pair in this network
is assumed to be known at all transmitters and receivers. Under an average
power constraint at each source, the sum-capacity of the C-MAC and the power
policy that achieves this capacity is developed. The conditions defining the
classes of strong and very strong ergodic IFCs are presented and the multicast
sum-capacity is shown to be tight for both classes.


title: Thermal bound entanglement in macroscopic systems and area laws

abstract:
  Does bound entanglement naturally appear in quantum many-body systems? We
address this question by showing the existence of bound-entangled thermal
states for harmonic oscillator systems consisting of an arbitrary number of
particles. By explicit calculations of the negativity for different partitions,
we find a range of temperatures for which no entanglement can be distilled by
means of local operations, despite the system being globally entangled. We
offer an interpretation of this result in terms of entanglement-area laws,
typical of these systems. Finally, we discuss generalizations of this result to
other systems, including spin chains.


title: Tagged particle process in continuum with singular interactions

abstract:
  By using Dirichlet form techniques we construct the dynamics of a tagged
particle in an infinite particle environment of interacting particles for a
large class of interaction potentials. In particular, we can treat interaction
potentials having a singularity at the origin, non-trivial negative part and
infinite range, as e.g., the Lennard-Jones potential.


title: Quantum dynamics in nonequilibrium environments

abstract:
  We present a formalism for studying the behaviour of quantum systems coupled
to nonequilibrium environments exhibiting nonGaussian fluctuations. We discuss
the role of a qubit as a detector of the statistics of environmental
fluctuations, as well as nonMarkovian effects in both weak and strong coupling
limits. We also discuss the differences between the influences of classical and
quantum environments. As examples of the application of this formalism we study
the dephasing and relaxation of a charge qubit coupled to nonequillibrium
electron transport through single and double quantum dots.


title: The Nagata automorphism is shifted linearizable

abstract:
  A polynomial automorphism $F$ is called {\em shifted linearizable} if there
exists a linear map $L$ such that $LF$ is linearizable. We prove that the
Nagata automorphism $N:=(X-Y\Delta -Z\Delta^2,Y+Z\Delta, Z)$ where
$\Delta=XZ+Y^2$ is shifted linearizable. More precisely, defining $L_{(a,b,c)}$
as the diagonal linear map having $a,b,c$ on its diagonal, we prove that if
$ac=b^2$, then $L_{(a,b,c)}N$ is linearizable if and only if $bc\not = 1$. We
do this as part of a significantly larger theory: for example, any exponent of
a homogeneous locally finite derivation is shifted linearizable. We pose the
conjecture that the group generated by the linearizable automorphisms may
generate the group of automorphisms, and explain why this is a natural
question.


title: Multiple X-ray bursts from long discharges in air

abstract:
  A lightning surge generator generates a high voltage surge with 1.2 microsec.
rise time. The generator fed a spark gap of two pointed electrodes at 0.7 to
1.2 m distances. Gap breakdown occurred between 0.1 and 3 microsec. after the
maximum generator voltage of approximately 850 kV. Various scintillator
detectors with different response time recorded bursts of hard radiation in
nearly all surges. The bursts were detected over the time span between
approximately half of the maximum surge voltage and full gap breakdown. The
consistent timing of the bursts with the high-voltage surge excluded background
radiation as source for the high intensity pulses. In spite of the symmetry of
the gap, negative surges produced more intense radiation than positive. This
has been attributed to additional positive discharges from the measurement
cabinet which occurred for negative surges. Some hard radiation signals were
equivalent to several MeV. Pile-up occurs of lesser energy X-ray quanta, but
still with a large fraction of these with an energy of the order of 100 keV.
The bursts occurred within the 4 nanosec. time resolution of the fastest
detector. The relation between the energy of the X-ray quanta and the signal
from the scintillation detector is quite complicated, as shown by the
measurements.


title: Quantum Zeno effect in atomic spin-exchange collisions

abstract:
  The suppression of spin-exchange relaxation in dense alkali-metal vapors
discovered in 1973 and governing modern atomic magnetometers is here
reformulated in terms of quantum measurement theory and the quantum Zeno
effect. This provides a new perspective of understanding decoherence in
spin-polarized atomic vapors.


title: A right inverse of the divergence for planar H\"older-$\alpha$ domains

abstract:
  If $\Omega\subset\R^n$ is a bounded domain, the existence of solutions ${\bf
u}\in H^1_0(\Omega)^n$ of ${div} {\bf u} = f$ for $f\in L^2(\Omega)$ with
vanishing mean value, is a basic result in the analysis of the Stokes
equations.
  In particular it allows to show the existence of a solution $({\bf u},p)\in
H^1_0(\Omega)^n\times L^2(\Omega)$, where ${\bf u}$ is the velocity and $p$ the
pressure.
  It is known that the above mentioned result holds when $\Omega$ is a
Lipschitz domain and that it is not valid for arbitrary H\"older-$\alpha$
domains.
  In this paper we prove that if $\Omega$ is a planar simply connected
H\"older-$\alpha$ domain, there exist right inverses of the divergence which
are continuous in appropriate weighted spaces, where the weights are powers of
the distance to the boundary. Moreover, we show that the powers of the distance
in the results obtained are optimal.
  In our results, the zero boundary condition is replaced by a weaker one. For
the particular case of domains with an external cusp of power type, we prove
that our weaker boundary condition is equivalent to the standard one. In this
case we show the well posedness of the Stokes equations in appropriate weighted
Sobolev spaces obtaining as a consequence the existence of a solution $({\bf
u},p)\in H^1_0(\Omega)^n\times L^r(\Omega)$ for some $r<2$ depending on the
power of the cusp.


title:
The UDF05 Follow-up of the HUDF: II. Constraints on Reionization from
  z-dropout Galaxies

abstract:
  [Abridged] We detect three (plus one less certain) z-dropout sources in two
separate fields of our UDF05 HST NICMOS images. These z~7 Lyman-Break Galaxy
(LBG) candidates allow us to constrain the Luminosity Function (LF) of the star
forming galaxy population at those epochs. By assuming a change in only M* and
adopting a linear evolution in redshift, anchored to the measured values at
z~6, the best fit evolution coefficient is found to be 0.43+-0.19 mag per unit
redshift (0.36+-0.18, if including all four candidates), which provides a value
of M*(z=7.2)=-19.7+-0.3. This implies a steady evolution for the LBG LF out to
z~7, at the same rate that is observed throughout the z~3 to 6 period. This
puts a strong constraint on the star-formation histories of z~6 galaxies, whose
ensemble star-formation rate density must be lower by a factor 2 at ~170 Myr
before the epoch at which they are observed. In particular, a large fraction of
stars in the z~6 LBG population must form at redshifts well above z~7.
Extrapolating this steady evolution of the LF out to higher redshifts, we
estimate that galaxies would be able to reionize the universe by z~6, provided
that the faint-end slope of the z>7 LF steepens to alpha~-1.9, and that faint
galaxies, with luminosities below the current detection limits, contribute a
substantial fraction of the required ionizing photons. This scenario gives
however an integrated optical depth to electron scattering that is ~2sigma
below the WMAP-5 measurement. Therefore, altogether, our results indicate that,
should galaxies be the primary contributors to reionization, either the
currently detected evolution of the galaxy population slows down at z>7, or the
LF evolution must be compensated by a decrease in metallicity and a
corresponding increase in ionization efficiency at these early epochs.


title:
On the field intersection problem of solvable quintic generic
  polynomials

abstract:
  We study a general method of the field intersection problem of generic
polynomials over an arbitrary field $k$ via formal Tschirnhausen
transformation. In the case of solvable quintic, we give an explicit answer to
the problem by using multi-resolvent polynomials.


title:
On Splitting Types, Discriminant Bounds, and Conclusive Tests for the
  Galois Group

abstract:
  Using the action of the Galois group of a normal extension of number fields,
we generalize and symmetrize various fundamental statements in algebra and
algebraic number theory concerning splitting types of prime ideals,
factorization types of polynomials modulo primes, and cycle types of the Galois
groups of polynomials. One remarkable example is the removal of all artificial
constraints from the Kummer-Dedekind Theorem that relates splitting and
factorization patterns. Finally, we present an elementary proof that the
discriminant of the splitting field of a monic irreducible polynomial with
integer coefficients has a computable upper bound in terms of the coefficients.
This result, combined with one of Lagarias et al., shows that tests of
polynomials for the cycle types of the Galois group are conclusive. In
particular, the Galois groups of monic irreducible cubics, quartics, and
quintics with integer coefficients can be completely determined in finitely
many steps (though not necessarily in one's lifetime).


title:
Structure analysis of interstellar clouds: II. Applying the
  Delta-variance method to interstellar turbulence

abstract:
  The Delta-variance analysis is an efficient tool for measuring the structural
scaling behaviour of interstellar turbulence in astronomical maps. In paper I
we proposed essential improvements to the Delta-variance analysis.
  In this paper we apply the improved Delta-variance analysis to i) a
hydrodynamic turbulence simulation with prominent density and velocity
structures, ii) an observed intensity map of rho Oph with irregular boundaries
and variable uncertainties of the different data points, and iii) a map of the
turbulent velocity structure in the Polaris Flare affected by the intensity
dependence on the centroid velocity determination.
  The tests confirm the extended capabilities of the improved Delta-variance
analysis. Prominent spatial scales were accurately identified and artifacts
from a variable reliability of the data were removed. The analysis of the
hydrodynamic simulations showed that the injection of a turbulent velocity
structure creates the most prominent density structures are produced on a scale
somewhat below the injection scale. The new analysis of a rho Oph continuum map
reveals an intermediate stage in the molecular cloud evolution showing both
signatures of the typical molecular cloud scaling behaviour and the formation
of condensed cores. When analysing the velocity structure of the Polaris Flare
we show that a universal power law connects scales from 0.03 pc to 3 pc.
However, a plateau in the Delta-variance spectrum around 5 pc indicates that
the visible large-scale velocity gradient is not converted directly into a
turbulent cascade.