title:
Bifurcations in a class of polycycles involving two saddle-nodes on a
  Mobius band

abstract:
  In this paper we study the bifurcations of a class of polycycles, called
lips, occurring in generic three-parameter smooth families of vector fields on
a M\"obius band. The lips consists of a set of polycycles formed by two
saddle-nodes, one attracting and the other repelling, connected by the
hyperbolic separatrices of the saddle-nodes and by orbits interior to both
nodal sectors. We determine, under certain genericity hypotheses, the maximum
number of limits cycles that may bifurcate from a graphic belonging to the lips
and we describe its bifurcation diagram.


title: Deciphering the spin of new resonances in Higgsless models

abstract:
  We study the potential of the CERN Large Hadron Collider (LHC) to probe the
spin of new massive vector boson resonances predicted by Higgsless models. We
consider its production via weak boson fusion which relies only on the coupling
between the new resonances and the weak gauge bosons. We show that the LHC will
be able to unravel the spin of the particles associated with the partial
restoration of unitarity in vector boson scattering for integrated luminosities
of 150-560 fb^-1, depending on the new state mass and on the method used in the
analyses.


title:
Structural Properties of Pseudo-Bulges, Classical Bulges and Elliptical
  Galaxies: an SDSS Perspective

abstract:
  We have performed 2D bulge/bar/disc decompositions using g, r and i-band
images of a representative sample of nearly 1000 galaxies from the Sloan
Digital Sky Survey. We show that the Petrosian concentration index is a better
proxy for bulge-to-total ratio than the global Sersic index. We show that
pseudo-bulges can be distinguished from classical bulges as outliers in the
Kormendy relation. We provide the structural parameters and distributions of
stellar masses of ellipticals, classical bulges, pseudo-bulges, discs and bars,
and find that 32 per cent of the total stellar mass in massive galaxies in the
local universe is contained in ellipticals, 36 per cent in discs, 25 per cent
in classical bulges, 3 per cent in pseudo-bulges and 4 per cent in bars.
Pseudo-bulges are currently undergoing intense star formation activity and
populate the blue cloud of the colour-magnitude diagram. Most (though not all)
classical bulges are quiescent and populate the red sequence of the diagram.
Classical bulges follow a correlation between bulge Sersic index and
bulge-to-total ratio, while pseudo-bulges do not. In addition, for a fixed
bulge-to-total ratio, pseudo-bulges are less concentrated than classical
bulges. Pseudo-bulges follow a mass-size relation similar to that followed by
bars, and different from that followed by classical bulges. In the fundamental
plane, pseudo-bulges occupy the same locus as discs. While these results point
out different formation processes for classical and pseudo-bulges, we also find
a significant overlap in their properties, indicating that the different
processes might happen concomitantly. Finally, classical bulges and ellipticals
follow offset mass-size relations, suggesting that high-mass bulges might not
be simply high-mass ellipticals surrounded by discs.


title: A Variational Study of the Nucleon Wavefunction

abstract:
  The structure of the nucleon is studied variationally on the lattice by
maximizing the overlap between the nucleon and a trial function generated by an
interpolating field containing variational parameters. We examine the effect of
the spatial extent of smeared quark sources, the degree of gauge field
smearing, the positions of smeared quark sources, inclusion of lower Dirac
components and of diquark substructure. Exploratory calculations with quenched
Wilson fermions at a pion mass of 900 MeV achieved overlaps as high as 80%, and
there was no evidence of diquark substructure.


title: Non-Abelian anyons: when Ising meets Fibonacci

abstract:
  We consider an interface between two non-Abelian quantum Hall states: the
Moore-Read state, supporting anyons of Ising type, and the k=2 NASS
(non-Abelian spin-singlet) state, supporting anyons of Fibonacci type. It is
shown that the interface supports neutral excitations described by a 1+1
dimensional conformal field theory with central charge c=7/10. We discuss
effects of the mismatch of the quantum statistical properties of the
quasi-holes between the two sides, as reflected by the interface theory.


title: Dependence of Effective Mass on Spin and Valley Degrees of Freedom

abstract:
  We measure the effective mass (m*) of interacting two-dimensional electrons
confined to an AlAs quantum well while we change the conduction-band valley
occupation and the spin polarization via the application of strain and magnetic
field, respectively. Compared to its band value, m* is enhanced unless the
electrons are fully valley and spin polarized. Incidentally, in the fully spin-
and valley-polarized regime, the electron system exhibits an insulating
behavior.


title: LES of an inclined jet into a supersonic cross-flow

abstract:
  This short article describes flow parameters, numerical method, and
animations of the fluid dynamics video LES of an Inclined Jet into a Supersonic
Cross-Flow (http://hdl.handle.net/1813/11480). Helium is injected through an
inclined round jet into a supersonic air flow at Mach 3.6. The video shows 2D
contours of Mach number and magnitude of density gradient, and 3D iso-surfaces
of Helium mass-fraction and vortical structures. Large eddy simulation with the
sub-grid scale (LES-SGS) stretched vortex model of turbulent and scalar
transport captures the main flow features: bow shock, Mach disk, shear layers,
counter-rotating vortices, and large-scale structures.


title: Regularity of Dirac-harmonic maps

abstract:
  For any $n$-dimensional compact spin Riemannian manifold $M$ with a given
spin structure and a spinor bundle $\Sigma M$, and any compact Riemannian
manifold $N$, we show an $\epsilon$-regularity theorem for weakly
Dirac-harmonic maps . As a consequence, any weakly Dirac-harmonic map is proven
to be smooth when n = 2. A weak convergence theorem for approximate
Dirac-harmonic maps is established when $n = 2$. For $n \ge 3$, we introduce
the notation of stationary Dirac-harmonic maps and obtain a Liouville theorem
for stationary Dirac-harmonic maps in $R^n$. If, additions, $\psi\in W^{1,p}$
for some $p>2n/3$, then we obtain an energy monotonicity formula and prove a
partial regularity theorem for any such a stationary Dirac-harmonic map.


title: Core-Collapse Astrophysics with a Five-Megaton Neutrino Detector

abstract:
  The legacy of solar neutrinos suggests that large neutrino detectors should
be sited underground. However, to instead go underwater bypasses the need to
move mountains, allowing much larger water Cherenkov detectors. We show that
reaching a detector mass scale of ~5 Megatons, the size of the proposed
Deep-TITAND, would permit observations of neutrino "mini-bursts" from
supernovae in nearby galaxies on a roughly yearly basis, and we develop the
immediate qualitative and quantitative consequences. Importantly, these
mini-bursts would be detected over backgrounds without the need for optical
evidence of the supernova, guaranteeing the beginning of time-domain MeV
neutrino astronomy. The ability to identify, to the second, every core collapse
in the local Universe would allow a continuous "death watch" of all stars
within ~5 Mpc, making practical many previously-impossible tasks in probing
rare outcomes and refining coordination of multi-wavelength/multi-particle
observations and analysis. These include the abilities to promptly detect
otherwise-invisible prompt black hole formation, provide advance warning for
supernova shock-breakout searches, define tight time windows for
gravitational-wave searches, and identify "supernova impostors" by the
non-detection of neutrinos. Observations of many supernovae, even with low
numbers of detected neutrinos, will help answer questions about supernovae that
cannot be resolved with a single high-statistics event in the Milky Way.


title:
Covariance of cross-correlations: towards efficient measures for
  large-scale structure

abstract:
  We study the covariance of the cross-power spectrum of different tracers for
the large-scale structure. We develop the counts-in-cells framework for the
multi-tracer approach, and use this to derive expressions for the full
non-Gaussian covariance matrix. We show, that for the usual auto-power
statistic, besides the off-diagonal covariance generated through gravitational
mode-coupling, the discreteness of the tracers and their associated sampling
distribution can generate strong off-diagonal covariance, and that this becomes
the dominant source of covariance as k>>k_f=2 pi/L. On comparison with the
derived expressions for the cross-power covariance, we show that the
off-diagonal terms can be suppressed, if one cross-correlates a high
tracer-density sample with a low one. Taking the effective estimator efficiency
to be proportional to the signal-to-noise ratio (SN), we show that, to probe
clustering as a function of physical properties of the sample, i.e. cluster
mass or galaxy luminosity, then the cross-power approach can out perform the
auto-power one by factors of a few. We confront the theory with measurements of
the mass-mass, halo-mass, and halo-halo power spectra from a large ensemble of
N-body simulations. We show that there is a significant SN advantage to be
gained from using the cross-power approach when studying the bias of rare
haloes. The analysis is repeated in configuration space and again SN
improvement is found. We estimate the covariance matrix for these samples, and
find strong off-diagonal contributions. The covariance depends on halo mass,
with higher mass samples having stronger covariance. In agreement with theory,
we show that the covariance is suppressed for the cross-power. This work points
the way towards improved estimators for clustering studies.


title: Quasi-local contribution to the scalar self-force: Non-geodesic Motion

abstract:
  We extend our previous calculation of the quasi-local contribution to the
self-force on a scalar particle to general (not necessarily geodesic) motion in
a general spacetime. In addition to the general case and the case of a particle
at rest in a stationary spacetime, we consider as examples a particle held at
rest in Reissner-Nordstrom and Kerr-Newman space-times. This allows us to most
easily analyse the effect of non-geodesic motion on our previous results and
also allows for comparison to existing results for Schwarzschild spacetime.


title:
3D vortex formation of rigid and flexible plates in impulsively starting
  motion

abstract:
  This fluid dynamics video shows three-dimensional vortex formation process
for plates in impulsive motion which is investigated experimentally by using
defocusing digital particle image velocimetry (DDPIV). Rigid and flexible plate
cases are compared in order to study the effect of flexibility on 3D vortex
formation and associated hydrodynamic forces. This study was motivated by the
general question of how the flexibility of flapping propulsors in flying and
swimming animals affects vortex formation and propulsive force. For translating
and rotating motion, the flexible plate generates a vortex morphology which is
drastically different from that of the rigid plate. We identified the
deflection of the tip region as the source of this difference. The flexible
plate does not produce a large peak for the hydrodynamic force at the impulsive
start and stop. This force trend is correlated with smooth vortex formation and
shedding processes.


title:
The "weighted ensemble" path sampling method is statistically exact for
  a broad class of stochastic processes and binning procedures

abstract:
  The "weighted ensemble" method, introduced by Huber and Kim, [G. A. Huber and
S. Kim, Biophys. J. 70, 97 (1996)], is one of a handful of rigorous approaches
to path sampling of rare events. Expanding earlier discussions, we show that
the technique is statistically exact for a wide class of Markovian and
non-Markovian dynamics. The derivation is based on standard path-integral (path
probability) ideas, but recasts the weighted-ensemble approach as simple
"resampling" in path space. Similar reasoning indicates that arbitrary
nonstatic binning procedures, which merely guide the resampling process, are
also valid. Numerical examples confirm the claims, including the use of bins
which can adaptively find the target state in a simple model.


title: Global Regularity of the 4D Restricted Euler Equations

abstract:
  We are concerned with the critical threshold phenomena in the Restricted
Euler (RE) equations. Using the spectral and trace dynamics we identify the
critical thresholds for 3D and the 4D restricted Euler equations. It is well
known that the 3D RE solutions blow up. Projected on the 3-sphere, the set of
initial eigenvalues which give rise to bounded stable solutions is reduced to a
single point, which confirms that 3D RE blowup is generic. In contrast, we
identify a surprisingly rich set of the initial spectrum on the 4-sphere which
yields global smooth solutions; thus, 4D regularity is generic.


title: Coherent Atom-Molecule Oscillations in a Bose-Fermi Mixture

abstract:
  We create atom-molecule superpositions in a Bose-Fermi mixture of Rb-87 and
K-40 atoms. The superpositions are generated by ramping an applied magnetic
field near an interspecies Fano-Feshbach resonance to coherently couple atom
and molecule states. Rabi- and Ramsey-type experiments show oscillations in the
molecule population that persist as long as 150 microseconds and have up to 50%
contrast. The frequencies of these oscillations are magnetic-field dependent
and consistent with the predicted molecule binding energy. This quantum
superposition involves a molecule and a pair of free particles with different
statistics (i.e. bosons and fermions), and furthers exploration of
atom-molecule coherence in systems without a Bose-Einstein condensate.


title: Vortex Induced Oscillations of Cylinders

abstract:
  This article submitted to the APS-DFD 2008 conference, accompanies the fluid
dynamics video depicting the various orientational dynamics of a hinged
cylinder suspended in a flow tank. The different behaviors displayed by the
cylinder range from steady orientation to periodic oscillation and even
autorotation. We illustrate these features using a phase diagram which captures
the observed phenomena as a function of Reynolds number and reduced inertia. A
hydrogen bubble flow visualization technique is also used to show vortex
shedding structure in the cylinder's wake which results in these oscillations.


title:
The q-Deformed Harmonic Oscillator, Coherent States, and the Uncertainty
  Relation

abstract:
  For a q-deformed harmonic oscillator, we find explicit coordinate
representations of the creation and annihilation operators, eigenfunctions, and
coherent states (the last being defined as eigenstates of the annihilation
operator). We calculate the product of the coordinate momentum uncertainties in
qoscillator eigenstates and in coherent states. For the oscillator, this
product is minimum in the ground state and equals 1/2, as in the standard
quantum mechanics. For coherent states, the $q$-deformation results in a
violation of the standard uncertainty relation; the product of the coordinate-
and momentumoperator uncertainties is always less than 1/2. States with the
minimum uncertainty, which tends to zero, correspond to the values of $\lambda$
near the convergence radius of the $q$-exponential.


title: A Simulation of Blood Cells in Branching Capillaries

abstract:
  The multi-cellular hydrodynamic interactions play a critical role in the
phenomenology of blood flow in the microcirculation. A fast algorithm has been
developed to simulate large numbers of cells modeled as elastic thin membranes.
For red blood cells, which are the dominant component in blood, the membrane
has strong resistance to surface dilatation but is flexible in bending. Our
numerical method solves the boundary integral equations built upon Green's
functions for Stokes flow in periodic domains. This fluid dynamics video is an
example of the capabilities of this model in handling complex geometries with a
multitude of different cells. The capillary branch geometries have been modeled
based upon observed capillary networks. The diameter of the branches varies
between 10-20 mum. A constant mean pressure gradient drives the flow. For the
purpose of this fluid dynamics video, the red blood cells are initiated as
biconcave discs and white blood cells and platelets are initiated as spheres
and ellipsoids respectively. The hematocrit as well as the average velocity
vary in the different branches due to the nonlinear interactions of the cells.
Physiologically, red blood cells enclose a concentrated solution of hemoglobin
which is about five times more viscous than plasma but for this simulation the
viscosity of the fluid inside and outside of red blood cells have been taken to
be the same.


title: Centroids and the Rapid Decay property in mapping class groups

abstract:
  We study a notion of a Lipschitz, permutation-invariant "centroid" for
triples of points in mapping class groups MCG(S), which satisfies a certain
polynomial growth bound. A consequence (via work of Drutu-Sapir or
Chatterji-Ruane) is the Rapid Decay Property for MCG(S).


title: Quantum state discrimination

abstract:
  It is a fundamental consequence of the superposition principle for quantum
states that there must exist non-orthogonal states, that is states that,
although different, have a non-zero overlap. This finite overlap means that
there is no way of determining with certainty in which of two such states a
given physical system has been prepared. We review the various strategies that
have been devised to discriminate optimally between non-orthogonal states and
some of the optical experiments that have been performed to realise these.


title:
Embeddings of vertex operator algebras associated to orthogonal affine
  Lie algebras

abstract:
  Let $L_{D_{\ell}}(-\ell +{3/2},0)$ (resp. $L_{B_{\ell}}(-\ell +{3/2},0)$) be
the simple vertex operator algebra associated to affine Lie algebra of type
$D_{\ell}^{(1)}$ (resp. $B_{\ell}^{(1)}$) with the lowest admissible
half-integer level $-\ell + {3/2}$. We show that $L_{D_{\ell}}(-\ell +{3/2},0)$
is a vertex subalgebra of $L_{B_{\ell}}(-\ell +{3/2},0)$ with the same
conformal vector. For $\ell =4$, $L_{D_{4}}(-{5/2},0)$ is a vertex subalgebra
of three copies of $L_{B_{4}}(-{5/2},0)$ contained in $L_{F_{4}}(-{5/2},0)$,
and all five of these vertex operator algebras have the same conformal vector.


title:
Black Holes in Pseudobulges and Spheroidals: A Change in the Black
  Hole-Bulge Scaling Relations at Low Mass

abstract:
  We investigate the relationship between black hole mass and host galaxy
properties for active galaxies with the lowest black hole masses currently
known in galaxy nuclei. Hubble Space Telescope imaging confirms that the host
galaxies have correspondingly low luminosity; they are ~1 mag below L*. In
terms of morphology, ~60% of the members of the sample are disk-dominated, and
all of these are consistent with containing a bulge or (more likely)
pseudobulge, while the remainder are compact systems with no discernible disk
component. In general the compact components of the galaxies do not obey the
fundamental plane of giant elliptical galaxies and classical bulges, but rather
are less centrally concentrated at a given luminosity, much like spheroidal
galaxies. Our results strongly confirm that a classical bulge is not a
requirement for a nuclear black hole. At the same time, the observed ratio of
black hole to bulge mass is nearly an order of magnitude lower in this sample
than that seen for classical bulges. While the M-sigma relation appears to
continue to low mass, it seems that black hole-galaxy scaling relations do
depend on galaxy structure.


title: Alphabet Sizes of Auxiliary Variables in Canonical Inner Bounds

abstract:
  Alphabet size of auxiliary random variables in our canonical description is
derived. Our analysis improves upon estimates known in special cases, and
generalizes to an arbitrary multiterminal setup. The salient steps include
decomposition of constituent rate polytopes into orthants, translation of a
hyperplane till it becomes tangent to the achievable region at an extreme
point, and derivation of minimum auxiliary alphabet sizes based on
Caratheodory's theorem.


title:
Unstable periodic orbits and heteroclinic connections in plane Couette
  flow

abstract:
  Equilibrium, traveling wave, and periodic orbit solutions of pipe, channel,
and plane Couette flows can now be computed precisely at Reynolds numbers above
the onset of turbulence. These invariant solutions capture the complex dynamics
of wall-bounded rolls and streaks and provide a framework for understanding
low-Reynolds turbulent shear flows as dynamical systems. We present fluid
dynamics videos of plane Couette flow illustrating periodic orbits, a close
pass of turbulent flow to a periodic orbit, and heteroclinic connections
between unstable equilibria.


title: Leaf roll-up and aquaplaning in strong winds and floods

abstract:
  Flexible plants, fungi, and sessile animals are thought to reconfigure in the
wind and water to reduce the drag forces that act upon them. In strong winds,
for example, leaves roll up into cone shapes that reduce flutter and drag when
compared to paper cut-outs with similar shapes and flexibility. During flash
floods, herbaceous broad leaves aquaplane on the surface of the water which
reduces drag. Simple mathematical models of a flexible beam immersed in a
two-dimensional flow will also reconfigure in flow. What is less understood is
how the mechanical properties of a two-dimensional leaf in a three-dimensional
flow will passively allow roll up and aquaplaning. In this study, we film leaf
roll-up and aquaplaning in tree and vine leaves in both strong winds and water
flows.


title: Vacuum-Gap Capacitors for Low-Loss Superconducting Resonant Circuits

abstract:
  Low-loss microwave components are used in many superconducting resonant
circuits from multiplexed readouts of low-temperature detector arrays to
quantum bits. Two-level system defects in amorphous dielectric materials cause
excess energy loss. In an effort to improve capacitor components, we have used
optical lithography and micromachining techniques to develop superconducting
parallel-plate capacitors in which lossy dielectrics are replaced by vacuum
gaps. Resonance measurements at 50 mK on lumped LC circuits that incorporate
these vacuum-gap capacitors (VGCs) reveal loss tangents at low powers as low as
4x10^{-5}, significantly lower than with capacitors using amorphous
dielectrics. VGCs are structurally robust, small, and easily scaled to
capacitance values above 100 pF.


title:
The homology of path spaces and Floer homology with conormal boundary
  conditions

abstract:
  We define the Floer complex for Hamiltonian orbits on the cotangent bundle of
a compact manifold satisfying non-local conormal boundary conditions. We prove
that the homology of this chain complex is isomorphic to the singular homology
of the natural path space associated to the boundary conditions.


title: Background-free propagation in loop quantum gravity

abstract:
  I review the definition of n-point functions in loop quantum gravity,
discussing what has been done and what are the main open issues. Particular
attention is dedicated to gauge aspects and renormalization.


title: Markov bases of binary graph models of K_4-minor free graphs

abstract:
  Markov width of a graph is a graph invariant defined as the maximum degree of
a Markov basis element for the corresponding graph model for binary contingency
tables. We show that a graph has Markov width at most four if and only if it
contains no $K_4$ as a minor, answering a question of Develin and Sullivant. We
also present a lower bound of order $\Omega(n^{2-\varepsilon})$ on the Markov
width of $K_n$.


title: Error Exponents of Optimum Decoding for the Interference Channel

abstract:
  Exponential error bounds for the finite-alphabet interference channel (IFC)
with two transmitter-receiver pairs, are investigated under the random coding
regime. Our focus is on optimum decoding, as opposed to heuristic decoding
rules that have been used in previous works, like joint typicality decoding,
decoding based on interference cancellation, and decoding that considers the
interference as additional noise. Indeed, the fact that the actual interfering
signal is a codeword and not an i.i.d. noise process complicates the
application of conventional techniques to the performance analysis of the
optimum decoder. Using analytical tools rooted in statistical physics, we
derive a single letter expression for error exponents achievable under optimum
decoding and demonstrate strict improvement over error exponents obtainable
using suboptimal decoding rules, but which are amenable to more conventional
analysis.


title: Disproving the Neighborhood Conjecture

abstract:
  We study the following Maker/Breaker game. Maker and Breaker take turns in
choosing vertices from a given n-uniform hypergraph F, with Maker going first.
Maker's goal is to completely occupy a hyperedge and Breaker tries to avoid
this. Beck conjectures that if the maximum neighborhood size of F is at most
2^(n-1) then Breaker has a winning strategy. We disprove this conjecture by
establishing an n-uniform hypergraph with maximum neighborhood size 3*2^(n-3)
where Maker has a winning strategy. Moreover, we show how to construct an
n-uniform hypergraph with maximum degree 2^(n-1)/n where Maker has a winning
strategy. Finally we show that each n-uniform hypergraph with maximum degree at
most 2^(n-2)/(en) has a proper halving 2-coloring, which solves another open
problem posed by Beck related to the Neighborhood Conjecture.


title: Tornadoes in a Microchannel

abstract:
  In non-dilute colloidal suspensions, gradients in particle volume fraction
result in gradients in electrical conductivity and permittivity. An externally
applied electric field couples with gradients in electrical conductivity and
permittivity and, under some conditions, can result in electric body forces
that drive the flow unstable forming vortices. The experiments are conducted in
square 200 micron PDMS microfluidic channels. Colloidal suspensions consisted
of 0.01 volume fraction of 2 or 3 micron diameter polystyrene particles in 0.1
mM Phosphate buffer and 409 mM sucrose to match particle-solution density. AC
electric fields at 20 Hz and strength of 430 to 600 V/cm were used. We present
a fluid dynamics video that shows the evolution of the particle aggregation and
formation of vortical flow. Upon application of the field particles aggregate
forming particle chains and three dimensional structures. These particles form
rotating bands where the axis of rotation varies with time and can collide with
other rotating bands forming increasingly larger bands. Some groups become
vortices with a stable axis of rotation. Other phenomena showed include counter
rotating vortices, colliding vortices, and non-rotating particle bands with
internal waves.


title:
A no-go theorem for a two-dimensional self-correcting quantum memory
  based on stabilizer codes

abstract:
  We study properties of stabilizer codes that permit a local description on a
regular D-dimensional lattice. Specifically, we assume that the stabilizer
group of a code (the gauge group for subsystem codes) can be generated by local
Pauli operators such that the support of any generator is bounded by a
hypercube of constant size. Our first result concerns the optimal scaling of
the distance $d$ with the linear size of the lattice $L$. We prove an upper
bound $d=O(L^{D-1})$ which is tight for D=1,2. This bound applies to both
subspace and subsystem stabilizer codes. Secondly, we analyze the suitability
of stabilizer codes for building a self-correcting quantum memory. Any
stabilizer code with geometrically local generators can be naturally
transformed to a local Hamiltonian penalizing states that violate the
stabilizer condition. A degenerate ground-state of this Hamiltonian corresponds
to the logical subspace of the code. We prove that for D=1,2 the height of the
energy barrier separating different logical states is upper bounded by a
constant independent of the lattice size L. The same result holds if there are
unused logical qubits that are treated as "gauge qubits". It demonstrates that
a self-correcting quantum memory cannot be built using stabilizer codes in
dimensions D=1,2. This result is in sharp contrast with the existence of a
classical self-correcting memory in the form of a two-dimensional ferromagnet.
Our results leave open the possibility for a self-correcting quantum memory
based on 2D subsystem codes or on 3D subspace or subsystem codes.


title: Quantum Criticality and the Alpha/Delta Puzzle

abstract:
  In this paper we suggest a novel explanation for the alpha-delta transition
in plutonium based on an analogy between the evolution of the actinide ground
state as a function of spin orbit coupling and the behaviour of thin film
superconductors in a magnetic field. The key point is that in metals with a low
carrier density spin-orbit interactions give rise to low energy monopole-like
solitons with quantized spin currents, which play much the same role as
Abrikosov vortices in thin film superconductors. In alpha-plutonium these
solitons form an ordered solid, while in impurity stabilized delta-plutonium
they form a pair condensate.


title:
Light quark energy loss in strongly-coupled N = 4 supersymmetric
  Yang-Mills plasma

abstract:
  We compute the penetration depth of a light quark moving through a large
$N_c$, strongly coupled $\mathcal N = 4$ supersymmetric Yang-Mills plasma using
gauge/gravity duality and a combination of analytic and numerical techniques.
We find that the maximum distance a quark with energy $E$ can travel through a
plasma is given by $\Delta x(E) = (\mathcal C/T) (E/T \sqrt\lambda)^{{1}/{3}}$
with $\mathcal C \approx 0.5$.


title: The bi-Hamiltonian structure and new solutions of KdV6 equation

abstract:
  We show that the KdV6 equation recently studied in [1,2] is equivalent to the
Rosochatius deformation of KdV equation with self-consistent sources
(RD-KdVESCS) recently presented in [9]. The $t$-type bi-Hamiltonian formalism
of KdV6 equation (RD-KdVESCS) is constructed by taking $x$ as evolution
parameter. Some new solutions of KdV6 equation, such as soliton, positon and
negaton solution, are presented.


title: On the infrared behavior of Landau gauge Yang-Mills theory

abstract:
  We discuss the properties of ghost and gluon propagators in the deep infrared
momentum region of Landau gauge Yang-Mills theory. Within the framework of
Dyson-Schwinger equations and the functional renormalization group we
demonstrate that it is only a matter of infrared boundary conditions whether
infrared scaling or decoupling occurs. We argue that the second possibility is
at odds with global BRST symmetry in the confining phase. For this purpose we
improve upon existing truncation schemes in particular with respect to
transversality and renormalization.


title:
Asymptotic Behavior of Stochastic Wave Equations with Critical Exponents
  on R^3

abstract:
  The existence of a random attractor in H^1(R^3) \times L^2(R^3) is proved for
the damped semilinear stochastic wave equation defined on the entire space R^3.
The nonlinearity is allowed to have a cubic growth rate which is referred to as
the critical exponent. The uniform pullback estimates on the tails of solutions
for large space variables are established. The pullback asymptotic compactness
of the random dynamical system is proved by using these tail estimates and the
energy equation method.


title: The characterizing variable for critical point in momentum space

abstract:
  The possible experimentally observable signal in momentum space for the
critical point, which is free from the contamination of statistical
fluctuations, is discussed. It is shown that the higher order scaled moment of
transverse momentum can serve as an appropriate signal for this point, provided
the transverse momentum distribution has a sudden change when energy increases
passing through the critical point. A 2-D percolation model with a linear
temperature gradient is constructed to check this suggestion. A sudden change
of third order scaled moment of transverse momentum is successfully observed.


title: Falling Jets of Particles in Viscous Fluids

abstract:
  This fluid dynamics video presents experiments and simulations of
gravity-driven particulate jets in viscous fluids at low Reynolds number. An
initially straight jet is shown to develop varicose modulations of its diameter
as it sediments under the action of gravity. While this instability is
qualitatively reminiscent of the classical Rayleigh-Plateau instability for
immiscible fluids, its mechanism has yet to be understood as neither inertia
nor surface tension play a role in the case of a dilute suspension at Re=0.


title: A global physician-oriented medical information system

abstract:
  We propose to improve medical decision making and reduce global health care
costs by employing a free Internet-based medical information system with two
main target groups: practicing physicians and medical researchers. After
acquiring patients' consent, physicians enter medical histories, physiological
data and symptoms or disorders into the system; an integrated expert system can
then assist in diagnosis and statistical software provides a list of the most
promising treatment options and medications, tailored to the patient.
Physicians later enter information about the outcomes of the chosen treatments,
data the system uses to optimize future treatment recommendations. Medical
researchers can analyze the aggregate data to compare various drugs or
treatments in defined patient populations on a large scale.


title:
Exact condition on the Kohn-Sham kinetic energy, and modern
  parametrization of the Thomas-Fermi density

abstract:
  We study the asymptotic expansion of the neutral-atom energy as the atomic
number Z goes to infinity, presenting a new method to extract the coefficients
from oscillating numerical data. We find that recovery of the correct expansion
is an exact condition on the Kohn-Sham kinetic energy that is important for the
accuracy of approximate kinetic energy functionals for atoms, molecules and
solids, when evaluated on a Kohn-Sham density. For example, this determines the
small gradient limit of any generalized gradient approximation, and conflicts
somewhat with the standard gradient expansion. Tests are performed on atoms,
molecules, and jellium clusters. We also give a modern, highly accurate
parametrization of the Thomas-Fermi density of neutral atoms.


title:
Enhanced coherent dynamics near a transition between neutral
  quantum-paraelectric and ionic ferroelectric phases in the quantum
  Blume-Emery-Griffiths model

abstract:
  Nonequilibrium dynamics are studied near the quantum phase transition point
in the one-dimensional quantum Blume-Emery-Griffiths model. Its pseudo-spin
component $ S^z $ represents an electric polarization, and $ (S^z)^2 $
corresponds to ionicity, in mixed-stack charge-transfer complexes that exhibit
a transition between neutral quantum-paraelectric and ionic ferroelectric (or
antiferroelectric) phases. The time-dependent Schr\"odinger equation is solved
for the exact many-body wave function in the quantum paraelectric phase. After
impact force is introduced on a polarization locally in space and time,
polarizations and ionicity coherently oscillate. The oscillation amplitudes are
large near the quantum phase transition point. The energy supplied by the
impact flows linearly into these oscillations, so that the nonequilibrium
behavior is uncooperative.


abstract:
  Convolutions of long-tailed and subexponential distributions play a major
role in the analysis of many stochastic systems. We study these convolutions,
proving some important new results through a simple and coherent approach, and
showing also that the standard properties of such convolutions follow as easy
consequences.


title: Floer homology of cotangent bundles and the loop product

abstract:
  We prove that the pair-of-pants product on the Floer homology of the
cotangent bundle of a compact manifold M corresponds to the Chas-Sullivan loop
product on the singular homology of the loop space of M. We also prove related
results concerning the Floer homological interpretation of the Pontrjagin
product and of the Serre fibration. The techniques include a Fredholm theory
for Cauchy-Riemann operators with jumping Lagrangian boundary conditions of
conormal type, and a new cobordism argument replacing the standard gluing
technique.


title: Localization and Kosterlitz-Thouless Transition in Disordered Graphene

abstract:
  We investigate disordered graphene with strong long-range impurities.
Contrary to the common belief that delocalization should persist in such a
system against any disorder, as the system is ex-pected to be equivalent to a
disordered two-dimensional Dirac Fermionic system, we find that states near the
Dirac points are localized for sufficiently strong disorder and the transition
between the localized and delocalized states is of Kosterlitz-Thouless type.
Our results show that the transition originates from bounding and unbounding of
local current vortices.


title:
Characterizing 1-Dof Henneberg-I graphs with efficient configuration
  spaces

abstract:
  We define and study exact, efficient representations of realization spaces of
a natural class of underconstrained 2D Euclidean Distance Constraint
Systems(EDCS) or Frameworks based on 1-dof Henneberg-I graphs. Each
representation corresponds to a choice of parameters and yields a different
parametrized configuration space. Our notion of efficiency is based on the
algebraic complexities of sampling the configuration space and of obtaining a
realization from the sample (parametrized) configuration. Significantly, we
give purely combinatorial characterizations that capture (i) the class of
graphs that have efficient configuration spaces and (ii) the possible choices
of representation parameters that yield efficient configuration spaces for a
given graph. Our results automatically yield an efficient algorithm for
sampling realizations, without missing extreme or boundary realizations. In
addition, our results formally show that our definition of efficient
configuration space is robust and that our characterizations are tight. We
choose the class of 1-dof Henneberg-I graphs in order to take the next step in
a systematic and graded program of combinatorial characterizations of efficient
configuration spaces. In particular, the results presented here are the first
characterizations that go beyond graphs that have connected and convex
configuration spaces.


title:
Optical Implementation of Non-locality with Coherent Light Fields for
  Quantum Communication

abstract:
  Polarization correlations of two distant observers are observed by using
coherent light fields based on Stapp's formulation of nonlocality. Using a
50/50 beam splitter transformation, a vertically polarized coherent light field
is found to be entangled with a horizontally polarized coherent noise field.
The superposed light fields at each output port of the beam splitter are sent
to two distant observers, where the fields are interfered and manipulated at
each observer by using a quarter wave plate and an analyzer. The interference
signal contains information of the projection angle of the analyzer, which is
hidden by the phase noises. The nonlocal correlations between the projection
angles of two distant observers are established by analyzing their data through
analog signal multiplication without any post-selection technique. This scheme
can be used to implement Ekert's protocol for quantum key distribution.


title:
Complete classification of compact four-manifolds with positive
  isotropic curvature

abstract:
  In this paper, we completely classify all compact 4-manifolds with positive
isotropic curvature. We show that they are diffeomorphic to $\mathbb{S}^4,$ or
$\mathbb{R}\mathbb{P}^4$ or quotients of $\mathbb{S}^3\times \mathbb{R}$ by a
cocompact fixed point free subgroup of the isometry group of the standard
metric of $\mathbb{S}^3\times \mathbb{R}$, or a connected sum of them.


title:
Theoretical and numerical investigations on shapes of planar lipid
  monolayer domains

abstract:
  Shapes of planar lipid monolayer domains at the air-water interface are
theoretically and numerically investigated by minimizing the formation energy
of the domains which consist of the surface energy, line tension energy, and
dipole electrostatic energy. The shape equation which describes boundary curves
of the domains at equilibrium state is derived from the first order variation
of the formation energy. A relaxation method is proposed to find the numerical
solutions of the shape equation. The theoretical and numerical results are in
good agreement with previous experimental observation. Some new shapes not
observed in previous experiments are also obtained, which awaits experimental
confirmation in the future.


title: On infinitesimal Cherednik algebras of gl_2

abstract:
  We prove that the center of an infinitesimal Cherednik algebra of $\mf{gl}_2$
is the polynomial algebra of two variables over the field of characteristic 0.
In positive characteristic we show that any infinitesimal Cherednik algebra is
a finitely generated module over its center.


title: Polarization singularity anisotropy: determining monstardom

abstract:
  C points, that is isolated points of circular polarization in transverse
fields of varying polarization, are classified morphologically into three
distinct types, known as lemons, stars and monstars. These morphologies are
interpreted here according to two natural parameters associated with the
singularity, namely the anisotropy of the C point, and the polarization azimuth
on the anisotropy axis. In addition to providing insight into singularity
morphology, this observation applies to the densities of the various
morphologies in isotropic random polarization speckle fields.


title:
Dynamic anti-plane sliding of dissimilar anisotropic linear elastic
  solids

abstract:
  The stability of steady, dynamic, anti-plane slipping at a planar interface
between two dissimilar anisotropic linear elastic solids is studied. The solids
are assumed to possess a plane of symmetry normal to the slip direction, so
that in-plane displacements and normal stress changes on the slip plane do not
occur. Friction at the interface is assumed to follow a rate and state
dependent law with velocity-weakening behavior in the steady state. The
stability to spatial perturbations of the form exp(ikx_1), where k is the
wavenumber and x_1 is the coordinate along the interface is studied. The
critical wavenumber magnitude, |k|_cr, above which there is stability and the
corresponding phase velocity, c, of the neutrally stable mode are obtained from
the stability analysis. Numerical plots showing the dependence of |k|_cr and c
on the unperturbed sliding velocity, V_o, are provided for various bi-material
combinations of practical interest.

categories: math-ph cond-mat.mtrl-sci math.MP physics.geo-ph


title: Point singularities of 3D stationary Navier-Stokes flows

abstract:
  This article characterizes the singularities of very weak solutions of 3D
stationary Navier-Stokes equations in a punctured ball which are sufficiently
small in weak $L^3$.


title:
On the behavior of physical parameters of aqueous solutions affected by
  the inerton field of Teslar technology

abstract:
  We present studies of the behavior of the permittivity of such liquid systems
as pure distilled water, alcohol and 50%-aqueous solutions of alcohol as
affected by the inerton field generated by a special signal generator contained
within a wrist-watch or bracelet made by so-called Teslar technology. It has
been found that the changes in fact are significant. The method employed has
allowed us to fix the value of frequency of the field generated by the Teslar
chip. The frequency has been determined to be approximately 8 Hz. The
phenomenological consideration and submicroscopic foundations of a significant
increase of the permittivity are studied taking into account an additional
interaction, namely the mass interaction between polar water molecules, which
is caused by the inerton field of the Teslar chip. This is one more proof of
Krasnoholovets' concept regarding the existence of a substructure of the matter
waves of moving/vibrating entities, i.e. the inerton field, which has been
predicted in a series of his previous works.


title:
Classical tests of general relativity in the Newtonian limit of
  Schwarzschild-de Sitter spacetime

abstract:
  Recently it has been shown that despite previous claims the cosmological
constant affects light bending. In the present article we study light bending
and the advance of Mercury's perihelion in the context of the Newtonian limit
of Schwarzschild-de Sitter spacetime employing the special relativistic
equivalence of mass and energy. In both cases, up to a constant factor, we find
the same results as in the full general relativistic treatment of the same
phenomena. These approximate and intuitive arguments demonstrate clearly what
effects should have been expected from the presence of $\Lambda$ in the general
relativistic treatment of these phenomena.


title:
Searching for spiral features in the outer Galactic disk. The field
  towards WR38 and WR38a

abstract:
  The detailed spiral structure in the outer Galactic disk is still poorly
known, and for several Galactic directions we rely on model extrapolations. One
of these regions is the fourth Galactic quadrant, in the sector comprised
between Vela and Carina (270 <l< 300) where no spiral arms have been detected
so far in the optical beyond 270. By means of deep UBVI photometry, we search
for spiral features in known low absorption windows.U photometry, although
demanding, constitutes a powerful tool to detect and characterize distant
aggregates, and allows to derive firmer distance estimates. We studied a
direction close to the tangent (l=290) to the Carina arm, in an attempt to
detect optical spiral tracers beyond the Carina branch, where radio
observations and models predictions indicate the presence of the extension of
the Perseus and Norma-Cygnus spiral arms in the fourth quadrant.Along this line
of sight, we detect three distinct groups of young stars. Two of them, at 2.5
and 6.0 kpc, belong to the Carina spiral arm (which is crossed twice in this
particular direction).The latter is here detected for the first time. The third
group, at a distance of 12.7 kpc, is part of the Perseus arm which lies beyond
the Carina arm, and constitutes the first optical detection of this arm in the
fourth Galactic quadrant. The position of this feature is compatible with HI
observations and model predictions. We furthermore present evidence that this
extremely distant group, formerly thought to be a star cluster (Shorlin 1), is
in fact a diffuse young population. In addition, our data-set does not support
the possible presence of the Monoceros Ring toward this direction. This study
highlights how multicolor optical studies can be effective to probe the spiral
structure in the outer Galactic disk.


title: Near Flat Space limit of strings on AdS_4 x CP^3

abstract:
  The non-linear nature of string theory on non-trivial backgrounds related to
the AdS/CFT correspondence suggests to look for simplifications. Two such
simplifications proved to be useful in studying string theory. These are the
pp-wave limit which describes point-like strings and the so called "near flat
space" limit which connects two different sectors of string theory -- pp-waves
and "giant magnons". Recently another example of AdS/CFT duality emerged -
$AdS_4/CFT_3$, which suggests duality between $\mathcal N=6$ CS theory and
superstring theory on $AdS_4\times \cp$. In this paper we study the "near flat
space" limit of strings on the $AdS_4\times \cp$ background and discuss
possible applications of the reduced theory.


title:
The bifurcation periods in low-mass X-ray binaries: the effect of
  magnetic braking and mass loss

abstract:
  The bifurcation period in low-mass X-ray binaries is the initial orbital pe-
riod which separates the formation of converging systems (which evolve with
decreasing orbital periods until the donor becomes degenerate) from the
diverging systems (which evolve with increasing orbital periods until the donor
star loses its envelope and a wide detached binary is formed). We calculate
systematically the bifurcation periods of binary systems with a 1.4M_\sun
neutron star and a 0.5-2M_\sun donor star, taking into account different kinds
of magnetic braking and mass loss mechanisms. Our results show that the
saturated magnetic braking can considerably decrease the values of bifurcation
period compared to the traditional magnetic braking, while the influence of
mass loss mechanisms on bifurcation periods is quite weak. We also develop a
semi-analytical method to compute the bifurcation period, the result of which
agrees well with the numerical method in the leading order.


title:
A note on conditional Akaike information for Poisson regression with
  random effects

abstract:
  A popular model selection approach for generalized linear mixed-effects
models is the Akaike information criterion, or AIC. Among others,
\cite{vaida05} pointed out the distinction between the marginal and conditional
inference depending on the focus of research. The conditional AIC was derived
for the linear mixed-effects model which was later generalized by
\cite{liang08}. We show that the similar strategy extends to Poisson regression
with random effects, where condition AIC can be obtained based on our
observations. Simulation studies demonstrate the usage of the criterion.


title:
Modified entanglement purification scheme with doubly entangled photon
  state

abstract:
  Recently Xiao et al. proposed a scheme for entanglement purification based on
doubly entangled photon states (Phys. Rev. A 77(2008) 042315). We modify their
scheme for improving the efficiency of entanglement purification. This modified
scheme contains two steps, i.e., the bit-flip error correction and the
entanglement purification of phase-flip errors. All the photon pairs in the
first step can be kept as all the bit-flip errors are corrected. For purifying
the phase-flip errors, a wavelength conversion process is needed. This scheme
has the advantage of high efficiency and it requires the original fidelity of
the entangled state wanted fay lower than other schemes, which makes it more
feasible in a practical application.


title: The Normal Distribution as a Limit of Generalized Sato-Tate Measures

abstract:
  With suitable order of limits, as p, m, and n all tend to infinity, the
distribution of the normalized trace of Frobenius on H^1 of a "random" plane
curve of degree n over the field with p^m elements, tends to a Gaussian
distribution. The same is true of a "random" curve of genus g over the field
with p^m elements.


title:
Quantum Communications with Compressed Decoherence Using Bright Squeezed
  Light

abstract:
  We propose a scheme for long-distance distribution of quantum entanglement in
which the entanglement between qubits at intermediate stations of the channel
is established by using bright light pulses in squeezed states coupled to the
qubits in cavities with a weak dispersive interaction. The fidelity of the
entanglement between qubits at the neighbor stations (10 km apart from each
other) obtained by postselection through the balanced homodyne detection of 7
dB squeezed pulses can reach F=0.99 without using entanglement purification, at
same time, the probability of successful generation of entanglement is 0.34.


title:
Nonlinear theory of fractional microwave-induced magnetoresistance
  oscillations in a dc-driven two-dimensional electron system

abstract:
  Microwave-induced nonlinear magnetoresistance in a dc-driven two-dimensional
electron system is examined using a multi-photon-assisted transport scheme
direct controlled by the current. It is shown that near the 2nd subharmonic of
the cyclotron resonance, the frequency of the resistivity oscillation with the
magnetic-field-normalized current-density is double that at the cyclotron
resonance and its harmonics, in excellent agreement with recent experimental
findings by Hatke {\it et al.} [Phys. Rev. Lett. {\bf 101}, 246811 (2008)]. The
current-induced alternative emergence of resonant two-photon and single-photon
processes is responsible for this frequency doubling. Near the third
subharmonic of the cyclotron resonance, the current-induced consecutive
appearance of resonant 0-/3-photon, two-photon, and single-photon processes may
lead to the frequency tripling of the resistivity oscillation.


title: N = 2 SUSY QED in nonlinear/linear SUSY relation

abstract:
  We show systematically the relation between a N = 2 nonlinear supersymmetric
(NLSUSY) model and a N = 2 SUSY QED theory by means of the superfield
formulation in two dimensional spacetime without imposing a priori any special
gauge conditions for a gauge superfield.


title: Hedging of claims with physical delivery under convex transaction costs

abstract:
  We study superhedging of contingent claims with physical delivery in a
discrete-time market model with convex transaction costs. Our model extends
Kabanov's currency market model by allowing for nonlinear illiquidity effects.
We show that an appropriate generalization of Schachermayer's robust no
arbitrage condition implies that the set of claims hedgeable with zero cost is
closed in probability. Combined with classical techniques of convex analysis,
the closedness yields a dual characterization of premium processes that are
sufficient to superhedge a given claim process. We also extend the fundamental
theorem of asset pricing for general conical models.


title: Dendrite fragmentation by catastrophic elastic remelting

abstract:
  The paper proposes a new fragmentation mechanism of dendrite arms. The
theoretical basis of this mechanism is a shift in the thermodynamical
equilibrium at the solid-liquid interface due to the presence of elastic
energy. This effect is modelled by the generalized Gibbs-Thomson condition [1],
where each term is calculated analytically using a simple Bernoulli-Euler beam
model. The resulting nonlinear system of ordinary differential equations is
integrated in time using a fully implicit scheme. It is demonstrated that there
is a critical level of loading, exceeding which causes a catastrophic reduction
of the neck cross section leading to dendrite detachment.


title:
Optical Identifications of Five INTEGRAL Hard X-ray Sources in the
  Galactic Plane Region

abstract:
  The results of optical identifications of five hard X-ray sources in the
Galactic plane region from the INTEGRAL all-sky survey are presented. The X-ray
data on one source (IGRJ20216+4359) are published for the first time. The
optical observations were performed with 1.5-m RTT-150 telescope (TUBITAK
National Observatory, Antalya, Turkey) and 6-m BTA telescope (Special
Astrophysical Observatory, Nizhny Arkhyz, Russia). A blazar, three Seyfert
galaxies, and a high-mass X-ray binary are among the identified sources.


title: Local tube realizations of CR-manifolds and maximal abelian subalgebras

abstract:
  For every CR-manifold germ (M,a) local tube realizations are characterized by
certain abelian subalgebras of the real Lie algebra hol(M,a) of all germs of
(real-analytic) infinitesimal transformations. For instance, if M is
holomorphically non-degenerate, every such subalgebra is maximal abelian and
the classification of all local tube realizations for (M,a) reduces to a purely
algebraic problem.


title: Volume of Separable States for Arbitrary $N$-dimensional System

abstract:
  In a celebrated paper ([Phys. Rev. A 58, 883 (1998)]), K. Zyczkowski, P.
Horodecki, A. Sanpera,and M. Lewenstein proved for the frst time a very
interesting theorem that the volume of separable quantum states is nonzero.
Inspired by their ideas, we obtain a general analytical lower bound of the
volume of separable states (VOSS) for arbitrary N-dimensional system. Our
results give quite simple and computable suffcient conditions for separability.
Moreover, for bipartite system, an upper bound of the VOSS is also presented.


title: Visualization Optimization : Application to the RoboCup Rescue Domain

abstract:
  In this paper we demonstrate the use of intelligent optimization
methodologies on the visualization optimization of virtual / simulated
environments. The problem of automatic selection of an optimized set of views,
which better describes an on-going simulation over a virtual environment is
addressed in the context of the RoboCup Rescue Simulation domain. A generic
architecture for optimization is proposed and described. We outline the
possible extensions of this architecture and argue on how several problems
within the fields of Interactive Rendering and Visualization can benefit from
it.


title: Muon Flux Limits for Majorana Dark Matter Particles

abstract:
  We analyze the effects of capture of dark matter (DM) particles, with
successive annihilations, predicted in the minimal walking technicolor model
(MWT) by the Sun and the Earth. We show that the Super-Kamiokande (SK) upper
limit on excessive muon flux disfavors the mass interval between 100-200 GeV
for MWT DM with a suppressed Standard Model interaction (due to a mixing
angle), and the mass interval between 0-1500 GeV for MWT DM without such
suppression, upon making the standard assumption about the value of the local
DM distribution. In the first case, the exclusion interval is found to be very
sensitive to the DM distribution parameters and can vanish at the extreme of
the acceptable values.


title:
High-resolution X-ray spectroscopy of the evolving shock in the 2006
  outburst of RS Ophiuchi

abstract:
  The evolution of the 2006 outburst of the recurrent nova RS Ophiuchi was
followed with 12 X-ray grating observations with Chandra and XMM-Newton. We
present detailed spectral analyses using two independent approaches. From the
best dataset, taken on day 13.8 after outburst, we reconstruct the temperature
distribution and derive elemental abundances. We find evidence for at least two
distinct temperature components on day 13.8 and a reduction of temperature with
time. The X-ray flux decreases as a power-law, and the power-law index changes
from -5/3 to -8/3 around day 70 after outburst. This can be explained by
different decay mechanisms for the hot and cool components. The decay of the
hot component and the decrease in temperature are consistent with radiative
cooling, while the decay of the cool component can be explained by the
expansion of the ejecta. We find overabundances of N and of alpha-elements,
which could either represent the composition of the secondary that provides the
accreted material or that of the ejecta. The N overabundance indicates
CNO-cycled material. From comparisons to abundances for the secondary taken
from the literature, we conclude that 20-40% of the observed nitrogen could
originate from the outburst. The overabundance of the alpha-elements is not
typical for stars of the spectral type of the secondary in the RS Oph system,
and white dwarf material might have been mixed into the ejecta. However, no
direct measurements of the alpha-elements in the secondary are available, and
the continuous accretion may have changed the observable surface composition.


title: Tori Embedded in S3 with Dense Asymptotic Lines

abstract:
  In this paper are given examples of tori T^2 embedded in S^3 with all their
asymptotic lines dense.


title:
Dynamical simulation of heavy-ion collisions in the energy range from a
  few tens MeV/A to a few hundreds MeV/A

abstract:
  The overlapping stage of heavy-ion reactions can be simulated by dynamical
microscopical models, such as those built on the basis of the Molecular
Dynamics (MD) approaches, allowing to study the fragment formation process. The
present performances of the Quantum MD (QMD) code developed at the University
of Milano are discussed, showing results concerning fragment and particle
production at bombarding energies up to $\lsim$ 700 MeV/A, as well as a
preliminary analysis on the isoscaling behaviour of isotopic yield ratios for
reactions with isospin composition N/Z in the (1 - 1.2) range, at a 45 MeV/A
bombarding energy.


title:
Clear evidence of charge conjugation and parity violation in K atoms
  from atomic permanent electric dipole moment experiments

abstract:
  Quantum mechanics thinks that atoms do not have permanent electric dipole
moment (EDM) because of their spherical symmetry. Therefore, there is no polar
atom in nature except for polar molecules. The electric susceptibility Xe
caused by the orientation of polar substances is inversely proportional to the
absolute temperature T while the induced susceptibility of atoms is temperature
independent. This difference in temperature dependence offers a means of
separating the polar and non-polar substances experimentally. Using special
capacitor our experiments discovered that the relationship between Xe of
Potassium atom and T is just Xe=B/T, where the slope B is approximately 283(K)
as polar molecules, but appears to be disordered using the traditional
capacitor. Its capacitance C at different voltage V was measured. The C-V curve
shows that the saturation polarization of K vapor has be observed when E more
than 105V/m and nearly all K atoms (over 98.9 per cent) are lined up with the
field! The ground state neutral K atom is polar atom with a large EDM: dK more
than 2.3*10-9e.cm.The results gave clear evidence for CP (charge conjugation
and parity) violation in K atoms. If K atom has a large EDM, why the linear
Stark effect has not been observed? The article discussed the question
thoroughly. Our results are easy to be repeated because the details of the
experiment are described in the article.


title: Normal Subgroups of Profinite Groups of Non-negative Deficiency

abstract:
  We initiate the study of profinite groups of non-negative deficiency. The
principal focus of the paper is to show that the existence of a finitely
generated normal subgroup of infinite index in a profinite group $G$ of
non-negative deficiency gives rather strong consequences for the structure of
$G$. To make this precise we introduce the notion of $p$-deficiency ($p$ a
prime) for a profinite group $G$. This concept is more useful in the study of
profinite groups then the notion of deficiency. We prove that if the
$p$-deficiency of $G$ is positive and $N$ is a finitely generated normal
subgroup such that the $p$-Sylow subgroup of $G/N$ is infinite and $p$ divides
the order of $N$ then we have $\cd_p(G)=2$, $\cd_p(N)=1$ and $\vcd_p(G/N)=1$
for the cohomological $p$-dimensions; moreover either the $p$-Sylow subgroup of
$G/N$ is virtually cyclic or the $p$-Sylow subgroup of $N$ is cyclic. A
profinite Poincar\'e duality group $G$ of dimension 3 at a prime $p$
($PD^3$-group) has deficiency 0. In this case we show that for $N$ and $p$ as
above either $N$ is $PD^1$ at $p$ and $G/N$ is virtually $PD^2$ at $p$ or $N$
is $PD^2$ at $p$ and $G/N$ is virtually $PD^1$ at $p$. In particular if $G$ is
pro-$p$ then either $N$ is infinite cyclic and $G/N$ is virtually Demushkin or
$N$ is Demushkin and $G/N$ is virtually infinite cyclic. We apply this results
to deduce structural information on the profinite completions of ascending
HNN-extensions of free groups. We also give some implications of our theory to
the congruence kernels of certain arithmetic groups.


title:
Structure formation during the collapse of a dipolar atomic
  Bose-Einstein condensate

abstract:
  We investigate the collapse of a trapped dipolar Bose-Einstein condensate.
This is performed by numerical simulations of the Gross-Pitaevskii equation and
the novel application of the Thomas-Fermi hydrodynamic equations to collapse.
We observe regimes of both global collapse, where the system evolves to a
highly elongated or flattened state depending on the sign of the dipolar
interaction, and local collapse, which arises due to dynamically unstable
phonon modes and leads to a periodic arrangement of density shells, disks or
stripes. In the adiabatic regime, where ground states are followed, collapse
can occur globally or locally, while in the non-adiabatic regime, where
collapse is initiated suddenly, local collapse commonly occurs. We analyse the
dependence on the dipolar interactions and trap geometry, the length and time
scales for collapse, and relate our findings to recent experiments.


title:
Stars and brown dwarfs, spatial distribution, multiplicity, X-rays,
  discs, and the complete mass function of the sigma Orionis cluster

abstract:
  The young sigma Orionis cluster in the Orion Belt is an incomparable site for
studying the formation and evolution of high-mass, solar-like, and low-mass
stars, brown dwarfs, and substellar objects below the deuterium burning mass
limit. The first version of the Mayrit catalogue was a thorough data
compilation of cluster members and candidates, which is regularly used by many
authors of different disciplines. I show two new applications of the catalogue
and advance preliminar results on very wide binarity and the initial mass
function from 18 to 0.035 Msol in sigma Orionis. The making-up of a new version
of the Mayrit catalogue with additional useful data is in progress.


title:
Preliminary results on a Virtual Observatory search for companions to
  Luyten stars

abstract:
  The Aladin sky atlas of the Virtual Observatory has shown to be a powerful
and easy-handling tool for the discovery, confirmation, and characterisation of
high proper-motion, multiple stellar systems of large separation in the solar
vicinity. Some of these systems have very low mass components (at the
star/brown dwarf boundary) and are amongst the least bound systems found to
date. With projected physical separations of up to tens of thousands
astronomical units, these systems represent a challenge for theoretical
scenarios of formation of very low-mass stars and brown dwarfs. Here we show
preliminary results of a novel "virtual" search of binary systems and
companions to Luyten stars with proper motions between 0.5 and 1.0 arcsec/a.


title:
What can we learn on the structure and the dynamics of the solar core
  with g modes?

abstract:
  The detection of the signature of dipole gravity modes has opened the path to
study the solar inner radiative zone. Indeed, g modes should be the best probes
to infer the properties of the solar nuclear core that represents more than
half of the total mass of the Sun. Concerning the dynamics of the solar core,
we can study how future observations of individual g modes could enhance our
knowledge of the rotation profile of the deep radiative zone. Applying
inversions on a set of real p-mode splittings coupled with either one or
several g modes, we have checked the improvement of the inferred rotation
profile when different error bars are considered for the g modes. Moreover,
using a new methodology based on the analysis of the almost constant separation
of the dipole gravity modes, we can introduce new constraints on solar models.
For that purpose, we can compare g-mode predictions computed from several
models including different physical inputs with the g-mode asymptotic signature
detected in GOLF data and calculate the correlation. This work shows the great
consistency between the signature of dipole gravity modes and our knowledge of
p-modes: incompatibility of data with a present standard model including the
Asplund composition


title: Music and Astronomy

abstract:
  What do Brian May (the Queen's lead guitarist), William Herschel and the
Jupiter Symphony have in common? And a white dwarf, a piano and Lagartija Nick?
At first glance, there is no connection between them, nor between Music and
Astronomy. However, there are many revealing examples of musical Astronomy and
astronomical Music. This four-page proceeding describes the sonorous poster
that we showed during the VIII Scientific Meeting of the Spanish Astronomical
Society.


title:
Formation, evolution and multiplicity of brown dwarfs and giant
  exoplanets

abstract:
  This proceeding summarises the talk of the awardee of the Spanish
Astronomical Society award to the the best Spanish thesis in Astronomy and
Astrophysics in the two-year period 2006-2007. The thesis required a tremendous
observational effort and covered many different topics related to brown dwarfs
and exoplanets, such as the study of the mass function in the substellar domain
of the young sigma Orionis cluster down to a few Jupiter masses, the relation
between the cluster stellar and substellar populations, the accretion discs in
cluster brown dwarfs, the frequency of very low-mass companions to nearby young
stars at intermediate and wide separations, or the detectability of Earth-like
planets in habitable zones around ultracool (L- and T-type) dwarfs in the solar
neighbourhood.


title:
Solar Energetic Particle Spectrum on 13 December 2006 Determined by
  IceTop

abstract:
  On 13 December 2006 the IceTop air shower array at the South Pole detected a
major solar particle event. By numerically simulating the response of the
IceTop tanks, which are thick Cherenkov detectors with multiple thresholds
deployed at high altitude with no geomagnetic cut-off, we determined the
particle energy spectrum in the energy range 0.6 to 7.6 GeV. This is the first
such spectral measurement using a single instrument with a well defined viewing
direction. We compare the IceTop spectrum and its time evolution with
previously published results and outline plans for improved resolution of
future solar particle spectra.


title: The Nature of Unresolved Soft X-ray Emission from the Galactic Disk

abstract:
  Although about 40% of the soft X-ray background emission in 0.4 to 1 keV
range has extragalactic origins and thus is totally blocked by the Galactic
absorption in midplane directions, it decreases at most by about 20 % in
midplane. Suzaku observation of the direction, (l, b) = (235, 0), showed an
OVII Kalpha emission intensity comparable with that of the MBM-12 on cloud
Suzaku observation, but revealed a narrow bump peaked at ~ 0.9 keV. The latter
component is partly filling the decrease of the extragalactic component in
midplane. The feature can be well represented by a thin thermal emission with a
temperature of about 0.8 keV. Because of the high pressure implied for
spatially extended hot gas, the emission is likely a sum of unresolved faint
sources. We consider a large fraction of the emission originates from faint dM
stars. We constructed a model spectrum for spatially unresolved dM stars that
consistently explains the observed spectrum and the surface brightness. The
model also suggests that the emission from dM stars decreases very rapidly with
increasing b, and thus that it cannot compensate entirely the decrease of the
extragalactic component at b ~ 2 - 10 deg.


title:
Parity Dependence in Strong Lens Systems as a Probe of Dark Matter
  Substructure

abstract:
  The amount of mass in small, dark matter clumps within galaxies
(substructure) is an important test of cold dark matter. One approach to
measuring the substructure mass fraction is to analyze the fluxes of images
that have been strongly lensed by a galaxy. Flux ratios between images that are
anomalous with respect to smooth (no substructure) models have previously
suggested that there is a greater amount of substructure than found in dark
matter simulations. One measure of anomalous flux ratios is parity dependence
-- that the fluxes of different images of a source are perturbed differently.
In this paper, we discuss parity dependence as a probe of dark matter
substructure. We find that reproducing the observed parity dependence requires
a significant alignment between concentrated dark matter clumps and images. The
results may imply a larger fraction of mass in substructures than suggested by
some dark matter simulations and that the observed parity dependence is
unlikely to be reproduced by luminous satellites of lens galaxies.


title:
Tilting, deformations and representations of linear groups over
  Euclidean algebras

abstract:
  We consider the dual space of linear groups over Dynkinian and Euclidean
algebras, i.e. finite dimensional algebras derived equivalent to the path
algebra of Dynkin or Euclidean quiver. We prove that this space contains an
open dense subset isomorphic to the product of dual spaces of full linear
groups and, perhaps, one more (explicitly described) space. The proof uses the
technique of bimodule categories, deformations and representations of quivers.


title: Application of two dimensional Frenkel-Kontorova model to nanotribology

abstract:
  A two-dimensional Frenkel-Kontorova model is set up. Its application to the
tribology is considered. The materials and the commensurability between two
layers strongly affect the static friction force. It is found that the static
friction force is larger between two layer of same materials than that for
different materials. For two-dimensional case the averaged static friction
force is larger for the uncommensurate case than that for the commensurate
case, which is completely different from one-dimensional case. The directions
of the propagation of the center of mass and the external driving force are
usually different except at some special symmetric directions. The possibility
to obtain superlubricity is suggested.


title: Particle production and reheating in the inflationary universe

abstract:
  Thermal field theory is applied to particle production rates in inflationary
models, leading to new results for catalysed, or two-stage decay, where massive
fields act as decay channels for the production of light fields. A numerical
investigation of the Bolztmann equation in an expanding universe shows that the
particle distributions produced during small amplitude inflaton oscillations or
alongside slowly moving inflaton fields can thermalise.


title:
Lattice and electronic anomalies of CaFe_2As_2 studied by Raman
  spectroscopy

abstract:
  We report inelastic light scattering experiments on CaFe_2As_2 in the
temperature range of 4 to 290 K. In in-plane polarizations two Raman-active
phonon modes are observed at 189 and 211 cm-1, displaying A_1g and B_1g
symmetries, respectively. Upon heating through the tetragonal-to-orthorhombic
transition at about T_S=173 K, the B_1g phonon undergoes a discontinuous drop
of the frequency by 4 cm-1 whereas the A_1g phonon shows a suppression of the
integrated intensity. Their linewidth increases strongly with increasing
temperature and saturates above T_S. This suggests (i) a first-order structural
phase transition and (ii) a drastic change of charge distribution within the
FeAs plane through T_S.


title: Entanglement-Enhanced Classical Communication

abstract:
  This thesis will be focused on the classical capacity of quantum channels,
one of the first areas treated by quantum information theorists. The problem is
fairly solved since some years. Nevertheless, this work will give me a reason
to introduce a consistent formalism of the quantum theory, as well as to review
fundamental facts about quantum non-locality and how it can be used to enhance
communication. Moreover, this reflects my dwelling in the spirit of classical
information theory, and it is intended to be a starting point towards a
thorough study of how quantum technologies can help to shape the future of
telecommunications.
  Whenever it was possible, heuristic reasonings were introduced instead of
rigorous mathematical proofs. This finds an explanation in that I am a
self-taught neophyte in the field, and just about every time I came across a
new concept, physical arguments were always more compelling to me than just
maths. The technical content of the thesis is twofold. On one hand, a quadratic
classification based on optimization programs that I devised for distinguishing
entangled states is presented in Chapter 4. In second place, a less difficult
yet I hope equally interesting technical part consists of versions of some
proofs throughout the text.


title: Counting cocircuits and convex two-colourings is #P-complete

abstract:
  We prove that the problem of counting the number of colourings of the
vertices of a graph with at most two colours, such that the colour classes
induce connected subgraphs is #P-complete. We also show that the closely
related problem of counting the number of cocircuits of a graph is #P-complete.


title:
Model for Tunneling-mediated Impurity Resonances in Bilayer Cuprate
  Superconductors

abstract:
  We have studied tunneling-mediated local density of states (LDOS) of the
surface layer of a bilayer cuprate, where a Zn impurity is located on the
second Cu-O layer. When the tunneling strength between two Cu-O layers is
larger than a critical value, the LDOS on the site just above the Zn impurity
first exhibits a resonant peak near the Fermi surface. The larger the tunneling
strength, the stronger the resonant peak. It is also shown that the height of
the resonant peak oscillates decreasingly with the distance from the site just
above the Zn impurity. The location of the resonant peak in the surface LDOS
depends on doping, energy gap, and the tunneling strength, and has an opposite
bias voltage to that on its nearest neighboring sites. The results could be
tested by the STM experiments and be used to further understand the electronic
properties of high temperature superconductors.


title: Wave Localization and Density Bunching in Pair Ion Plasmas

abstract:
  By investigating the nonlinear propagation of high intensity electromagnetic
(EM) waves in a pair ion plasma, whose symmetry is broken via contamination by
a small fraction of high mass immobile ions, it is shown that this new and
interesting state of (laboratory created) matter is capable of supporting
structures that strongly localize and bunch the EM radiation with density
excess in the region of localization. Testing of this prediction in controlled
laboratory experiments can lend credence, inter alia, to conjectures on
structure formation (via the same mechanism) in the MEV era of the early
universe.


title:
Supermassive black holes, star formation and downsizing of elliptical
  galaxies

abstract:
  The overabundance of Mg relative to Fe, observed in the nuclei of bright
ellipticals, and its increase with galactic mass, poses a serious problem for
all current models of galaxy formation. Here we improve on the one-zone
chemical evolution models for elliptical galaxies by taking into account
positive feedback produced in the early stages of super-massive central black
hole growth. We can account for both the observed correlation and the scatter
if the observed anti-hierarchical behaviour of the AGN population couples to
galaxy assembly and results in an enhancement of the star formation efficiency
which is proportional to galactic mass. At low and intermediate galactic
masses, however, a slower mode for star formation suffices to account for the
observational properties.


title: Modeling of Social Transitions Using Intelligent Systems

abstract:
  In this study, we reproduce two new hybrid intelligent systems, involve three
prominent intelligent computing and approximate reasoning methods: Self
Organizing feature Map (SOM), Neruo-Fuzzy Inference System and Rough Set Theory
(RST),called SONFIS and SORST. We show how our algorithms can be construed as a
linkage of government-society interactions, where government catches various
states of behaviors: solid (absolute) or flexible. So, transition of society,
by changing of connectivity parameters (noise) from order to disorder is
inferred.


title:
Interactions Between Mn_12-ac and Thin Gold Films: Using Mn_12-ac as
  Scattering Centers

abstract:
  We explore the electronic interactions between a thin gold film and a surface
layer of the molecular magnet Mn_12-acetate. Magnetoresistance measurements of
the gold allow characterization of the interactions by comparison with the
theoretical predictions of weak localization. We find that the presence of
Mn_12-acetate on the surface of the gold film leads to a reduction in elastic
scattering while increasing the spin scattering of the conduction electrons.
This is the first experimental evidence of molecular magnets being used as
scattering centers for an adjacent metallic film.


title: Robust ergodic properties in partially hyperbolic dynamics

abstract:
  We study ergodic properties of partially hyperbolic systems whose central
direction is mostly contracting. Earlier work of Bonatti, Viana about existence
and finitude of physical measures is extended to the case of local
diffeomorphisms. Moreover, we prove that such systems constitute a C^2-open set
in which statistical stability is a dense property. In contrast, all mostly
contracting systems are shown to be stable under small random perturbations.


title:
Hydrophobic Interactions and Dewetting between Plates with Hydrophobic
  and Hydrophilic Domains

abstract:
  We study by molecular dynamics simulations the wetting/dewetting transition
and the dependence of the free energy on distance between plates that contain
both hydrophobic and hydrophilic particles. We show that dewetting and strength
of hydrophobic interaction is very sensitive to the distribution of hydrophobic
and hydrophilic domains. In particular, we find that plates characterized by a
large domain of hydrophobic sites induce a dewetting transition and an
attractive solvent-induced interaction. On the other hand, a homogeneous
distribution of the hydrophobic and hydrophilic particles on the plates
prevents the dewetting transition and produces a repulsive solvent-induced
interaction. We also present results for a kind of Janus interface in which one
plate consists of hydrophobic particles and the other of hydrophilic particles
showing that the inter-plate gap remains wet until steric constraints at small
separations eject the water molecules. Our results indicate that the Cassie
equation, for the contact angle of a heterogeneous plate, can not be used to
predict the critical distance of dewetting. These results indicate that
hydrophobic interactions between nanoscale surfaces with strong large
length-scale hydrophobicity can be highly cooperative and thus they argue
against additivity of the hydrophobic interactions between different surface
domains in these cases. These findings are pertinent to certain protein-protein
interactions where additivity is commonly assumed.


title: Spectroscopy of Hadrons with b Quarks

abstract:
  Recent experimental results on the spectroscopy of B hadrons are presented.
The focus is primarily on the heavier states currently accessible only at the
Tevatron and the B factories running at the Upsilon(5S) resonance, i.e., Bs*,
the L = 1 orbitally excited states B** and $Bs**, and the new b-baryon states
Sigma(*)_b, Xi_b, and Omega_b.


title: A Remark on Nonlinear Dirac Equations

abstract:
  For a $n$-dimensional spin manifold $M$ with a fixed spin structure and a
spinor bundle $\Sigma M$, we prove an $\epsilon$-regularity theorem for weak
solutions to the nonlinear Dirac equation of cubic nonlinearity. This, in
particular, answers a regularity question raised by Chen-Jost-Wang when $n=2$.


title: Structural fuzziness of large gold clusters

abstract:
  The energetic ground state of gold clusters with up to 314 atoms consists of
rather complicated geometries that have only a weak resemblance to the perfect
icosahedra, decahedra and octahedra that are encountered for some magic
numbers. The structure changes in most cases completely by the addition of a
single atom. Other low energy structures are so close in energy that their
Boltzmann weight is not negligible at room temperature.


title: High degree graphs contain large-star factors

abstract:
  We show that any finite simple graph with minimum degree $d$ contains a
spanning star forest in which every connected component is of size at least
$\Omega((d/\log d)^{1/3})$. This settles a problem of J. Kratochvil.


title: Continued Fraction Expansions of Matrix Eigenvectors

abstract:
  We examine various properties of the continued fraction expansions of matrix
eigenvector slopes of matrices from the SL(2, Z) group. We calculate the
average period length, maximum period length, average period sum, maximum
period sum and the distributions of 1s 2s and 3s in the periods versus the
radius of the Ball within which the matrices are located. We also prove that
the periods of continued fraction expansions from the real irrational roots of
x2 + px + q = 0 are always palindromes.


title:
The performance of Minima Hopping and Evolutionary Algorithms for
  cluster structure prediction

abstract:
  We compare Evolutionary Algorithms with Minima Hopping for global
optimization in the field of cluster structure prediction. We introduce a new
{\em average offspring} recombination operator and compare it with previously
used operators. Minima Hopping is improved with a {\em softening} method and a
stronger feedback mechanism. Test systems are atomic clusters with
Lennard-Jones interaction as well as silicon and gold clusters described by
force fields. The improved Minima Hopping is found to be well-suited to all
these homoatomic problems. The evolutionary algorithm is more efficient for
systems with compact and symmetric ground states, including LJ$_{150}$, but it
fails for systems with very complex energy landscapes and asymmetric ground
states, such as LJ$_{75}$ and silicon clusters with more than 30 atoms. Both
successes and failures of the evolutionary algorithm suggest ways for its
improvement.


title: Cohomology rings of certain seven dimensional manifolds

abstract:
  We calculate the cohomology rings of a collection of seven dimensional
manifolds supporting an S^3 x S^3-action with one dimensional orbit space.
These manifolds are of interest to differential geometers studying non-negative
and positive sectional curvature. From this collection, we identify several
families of manifolds for which there exist well-known topological invariants
distinguishing homeomorphism and diffeomorphism types.


title: Nonadiabatic wavepacket dynamics: k-space formulation

abstract:
  The time evolution of wavepackets in crystals in the presence of a
homogeneous electric field is formulated in k-space in a numerically tractable
form. The dynamics is governed by separate equations for the motion of the
waveform in k-space and for the evolution of the underlying Bloch-like states.
A one-dimensional tight-binding model is studied numerically, and both Bloch
oscillations and Zener tunneling are observed. The long-lived Bloch
oscillations of the wavepacket center under weak fields are accompanied by
oscillations in its spatial spread. These are analyzed in terms of a k-space
expression for the spread having contributions from both the quantum metric and
the Berry connection of the Bloch states. We find that when sizeable spread
oscillations do occur, they are mostly due to the latter term.


title: Integral Deligne Cohomology for Real Varieties

abstract:
  We develop an integral version of Deligne cohomology for smooth proper real
varieties. For this purpose the role played by singular cohomology in the
complex case has to be replaced by ordinary bigraded G-equivariant cohomology,
where G=Gal(C/R). This is the G-equivariant counterpart of singular cohomology.
We establish the basic properties of the theory and give a geometric
interpretation for the groups in dimension 2 in weights 1 and 2.


title:
Search for High-Mass \boldmath$e^+e^-$ Resonances in \boldmath$p\bar{p}$
  Collisions at \boldmath$\sqrt{s}=$1.96 TeV

abstract:
  A search for high-mass resonances in the $e^+e^-$ final state is presented
based on 2.5 fb$^{-1}$ of $\sqrt{s}=$1.96 TeV $p\bar{p}$ collision data from
the CDF II detector at the Fermilab Tevatron. The largest excess over the
standard model prediction is at an $e^+e^-$ invariant mass of 240 GeV/$c^2$.
The probability of observing such an excess arising from fluctuations in the
standard model anywhere in the mass range of 150--1,000 GeV/$c^2$ is 0.6%
(equivalent to 2.5 $\sigma$). We exclude the standard model coupling $Z'$ and
the Randall-Sundrum graviton for $k/\overline{M}_{Pl}=0.1$ with masses below
963 and 848 GeV/$c^2$ at the 95% credibility level, respectively.


title: Abstract commensurators of profinite groups

abstract:
  In this paper we initiate a systematic study of the abstract commensurators
of profinite groups. The abstract commensurator of a profinite group $G$ is a
group $Comm(G)$ which depends only on the commensurability class of $G$. We
study various properties of $Comm(G)$; in particular, we find two natural ways
to turn it into a topological group. We also use $Comm(G)$ to study topological
groups which contain $G$ as an open subgroup (all such groups are totally
disconnected and locally compact). For instance, we construct a topologically
simple group which contains the pro-2 completion of the Grigorchuk group as an
open subgroup. On the other hand, we show that some profinite groups cannot be
embedded as open subgroups of compactly generated topologically simple groups.
Several celebrated rigidity theorems, like Pink's analogue of Mostow's strong
rigidity theorem for simple algebraic groups defined over local fields and the
Neukirch-Uchida theorem, can be reformulated as structure theorems for the
commensurators of certain profinite groups.


title:
On characterising strong bisimilarity in a fragment of CCS with
  replication

abstract:
  We provide a characterisation of strong bisimilarity in a fragment of CCS
that contains only prefix, parallel composition, synchronisation and a limited
form of replication. The characterisation is not an axiomatisation, but is
instead presented as a rewriting system. We discuss how our method allows us to
derive a new congruence result in the $\pi$-calculus: congruence holds in the
sub-calculus that does not include restriction nor sum, and features a limited
form of replication. We have not formalised the latter result in all details.


title: Electromagnetic origin of mass due to folded pseudo-coordinates

abstract:
  Nullification of the Einstein tensor curvature for the elementary material
space with active gravitational field (radial source) and passive field
distribution of its inertial particle (radial sink) maintains the conceptual
equivalence of collinear active and passive energy-momentum densities of the
nonlocal energy-matter carrier in General Relativity (GR). The Ricci scalar
curvature in the Lagrangian for electron's material space is related to active
and passive real mass densities with residual positive energy, while
electromagnetic (EM) active and passive imaginary mass densities produce a
traceless energy density. One four-potential in geometrical sink-source
identities universally forms gravitational and electromagnetic fields of the
complex mass current. EM vector equalities balance anti-collinear four flows of
active and passive imaginary masses (called electric charges). Similar GR
vector equalities take into account twin coupling of inseparable unlike mass
densities existing due to the forth-coordinate symmetry, $ dt = |\pm idx^4/c|$,
in the Minkowski four-interval. Two equal pseudo-coordinates $\pm ix^o\equiv
\pm x^4 $ serve for equal unlike masses of the same inertial body that results
in collinear active and passive four-currents of real masses with net
energy-momentum for collisions and measurements. Couples of unlike twin masses
can simultaneously radiate-absorb paired vector waves with zero-balanced
Poynting flows for real-time observations in the two-body gravitational system.
Such paired vector waves form tensor gravitons which cannot be screened by
third bodies or intercepted by interferometers.


title: Initial Offset Placement in p2p Live Streaming Systems

abstract:
  Initial offset placement in p2p streaming systems is studied in this paper.
Proportional placement (PP) scheme is proposed. In this scheme, peer places the
initial offset as the offset reported by other reference peer with a shift
proportional to the buffer width or offset lag of this reference peer. This
will introduce a stable placement that supports larger buffer width for peers
and small buffer width for tracker. Real deployed placement method in PPLive is
studied through measurement. It shows that, instead of based on offset lag, the
placement is based on buffer width of the reference peer to facilitate the
initial chunk fetching. We will prove that, such a PP scheme may not be stable
under arbitrary buffer occupation in the reference peer. The required average
buffer width then is derived. A simple good peer selection mechanism to check
the buffer occupation of reference peer is proposed for a stable PP scheme
based on buffer width


title: Global existence and long term behavior of 2d electro-hydrodynamics

abstract:
  We study the equations of a two dimensional incompressible Newtonian fluid
coupled with a dispersive parabolic-elliptic system on bounded domains. Global
in time weak solutions are shown to exist and converge with a rate to the
stationary solution for L^2 initial data. This paper extends and improves on a
body of work surrounding the Debye-Huckel system to the hydrodyanamical case.


title: On Dimensional Degression in AdS(d)

abstract:
  We analyze the pattern of fields in d+1 dimensional anti-de Sitter space in
terms of those in d dimensional anti-de Sitter space. The procedure, which is
neither dimensional reduction nor dimensional compactification, is called
dimensional degression. The analysis is performed group-theoretically for all
totally symmetric bosonic and fermionic representations of the anti-de Sitter
algebra. The field-theoretical analysis is done for a massive scalar field in
AdS(d+d$^\prime$) and massless spin one-half, spin one, and spin two fields in
AdS(d+1). The mass spectra of the resulting towers of fields in AdS(d) are
found. For the scalar field case, the obtained results extend to the shadow
sector those obtained by Metsaev in [1] by a different method.


title: The Equitable Basis for sl_2

abstract:
  This article contains an investigation of the equitable basis for the Lie
algebra sl_2. Denoting this basis by {x,y,z}, we have
  [x,y] = 2x + 2y, [y,z] = 2y + 2z, [z, x] = 2z + 2x.
  One focus of our study is the group of automorphisms G generated by exp(ad
x*), exp(ad y*), exp(ad z*), where {x*,y*,z*} is the basis for sl_2 dual to
{x,y,z} with respect to the trace form (u,v) = tr(uv). We show that G is
isomorphic to the modular group PSL_2(Z). Another focus of our investigation is
the lattice L=Zx+Zy+Zz. We prove that the orbit G(x) equals {u in L |(u,u)=2}.
We determine the precise relationship between (i) the group G, (ii) the group
of automorphisms for sl_2 that preserve L, (iii) the group of automorphisms and
antiautomorphisms for sl_2 that preserve L, and (iv) the group of isometries
for (,) that preserve L. We obtain analogous results for the lattice L*
=Zx*+Zy*+Zz*. Relative to the equitable basis, the matrix of the trace form is
a Cartan matrix of hyperbolic type; consequently,we identify the equitable
basis with the set of simple roots of the corresponding Kac-Moody Lie algebra
g. Then L is the root lattice for g and 1/2L* is the weight lattice, and G(x)
coincides with the set of real roots for g. Using L, L*, and G, we give several
descriptions of the isotropic roots for g and show that each isotropic root has
multiplicity 1. We describe the finite-dimensional sl_2-modules from the point
of view of the equitable basis. In the final section, we establish a connection
between the Weyl group orbit of the fundamental weights of g and Pythagorean
triples.


title: Divisibility, Smoothness and Cryptographic Applications

abstract:
  This paper deals with products of moderate-size primes, familiarly known as
smooth numbers. Smooth numbers play a crucial role in information theory,
signal processing and cryptography.
  We present various properties of smooth numbers relating to their
enumeration, distribution and occurrence in various integer sequences. We then
turn our attention to cryptographic applications in which smooth numbers play a
pivotal role.


title:
Hecke-Clifford Algebras and Spin Hecke Algebras IV: Odd Double Affine
  Type

abstract:
  We introduce an odd double affine Hecke algebra (DaHa) generated by a
classical Weyl group W and two skew-polynomial subalgebras of anticommuting
generators. This algebra is shown to be Morita equivalent to another new DaHa
which are generated by W and two polynomial-Clifford subalgebras. There is yet
a third algebra containing a spin Weyl group algebra which is Morita
(super)equivalent to the above two algebras. We establish the PBW properties
and construct Verma-type representations via Dunkl operators for these
algebras.