title:
Ordered, disordered and coexistent stable vortex lattices in NbSe_2
  single crystals

abstract:
  It is commonly accepted that the peak effect (PE) in the critical current
density of type II superconductors is a consequence of an order-disorder
transition in the vortex lattice (VL). Examination of vortex lattice
configurations (VLCs) in its vicinity requires the use of experimental
techniques that exclude current induced VL reorganization. By means of linear
ac susceptibility experiments in the Campbell regime, where vortices are forced
to oscillate (harmonically) around their effective pinning potentials, we
explore quasi-static stable and metastable VLCs in NbSe_{2} single crystals
near the PE. We identify three different regions: for T<T_{1}(H), stable VLCs
are maximally ordered. For T>T_{2}(H) configurations are fully disordered and
no metastability is observed. In the T_{1}<T<T_{2} region we find temperature
dependent stable configurations with intermediate degree of disorder, possibly
associated to coexistence of ordered and disordered lattices throughout the PE.
A simple estimation of the equilibrium proportion of ordered and disordered
domains is provided.


title:
A Coordinate-Free Construction for a Class of Integrable
  Hydrodynamic-Type Systems

abstract:
  Using a (1,1)-tensor L with zero Nijenhuis torsion and maximal possible
number (equal to the number of dependent variables) of distinct, functionally
independent eigenvalues we define, in a coordinate-free fashion, the seed
systems which are weakly nonlinear semi-Hamiltonian systems of a special form,
and an infinite set of conservation laws for the seed systems.
  The reciprocal transformations constructed from these conservation laws yield
a considerably larger class of hydrodynamic-type systems from the seed systems,
and we show that these new systems are again defined in a coordinate-free
manner, using the tensor L alone, and, moreover, are weakly nonlinear and
semi-Hamiltonian, so their general solution can be obtained by means of the
generalized hodograph method of Tsarev.


title:
Development and Numerical Analysis of "Black-box" Counterpropagating
  Wave Algorithm for Exact Quantum Scattering Calculations

abstract:
  In a recent series of papers [J. Chem. Phys. 121 4501 (2004), J. Chem. Phys.
124 034115 (2006), J. Chem. Phys. 124 034116 (2006)] a bipolar
counter-propagating wave decomposition, Psi = Psi+ + Psi-, was presented for
stationary bound states Psi of the one-dimensional Shrodinger equation, such
that the components Psi+- approach their semiclassical WKB analogs in the large
action limit. The corresponding bipolar quantum trajectories are classical-like
and well-behaved, even when Psi has many nodes, or is wildly oscillatory. In
this paper, the earlier results are used to construct a universal ``black-box''
algorithm, numerically robust, stable and efficient, for computing accurate
scattering quantities of any quantum dynamical system in one degree of freedom.


title:
Direct observation of a Fermi surface and superconducting gap in
  LuNi2B2C

abstract:
  We measured the Fermi surface (FS), band dispersion and superconducting gap
in LuNi2B2C using Angle Resolved Photoemission Spectroscopy. Experimental data
were compared with the tight-binding version of the Linear Muffin-Tin Orbital
(LMTO) method and Linearized Augmented Plane-Wave (LAPW) calculations. We found
reasonable agreement between the two calculations and experimental data. The
measured FS exhibits large parallel regions with a nesting vector that agrees
with a previous positron annihilation study and calculations of the generalized
susceptibility. The measured dispersion curves also agree reasonably well with
the TB-LMTO calculations, albeit with some differences in the strength of the
hybridization. In addition, the spectrum in the superconducting state revealed
a 2meV superconducting gap. The data also clearly shows the presence of a
coherent peak above the chemical potential, that originates from thermally
excited electrons above the energy of 2 delta. This feature was not previously
observed in the Lu-based material.


title: Non-linear dispersive regime of cavity QED: The dressed dephasing model

abstract:
  Systems in the dispersive regime of cavity quantum electrodynamics (QED) are
approaching the limits of validity of the dispersive approximation. We present
a model which takes into account nonlinear corrections to the dressing of the
atom by the field. We find that in the presence of pure dephasing, photons
populating the cavity act as a heat bath on the atom, inducing incoherent
relaxation and excitation. These effects are shown to reduce the achievable
signal-to-noise ratio in cavity QED realizations where the atom is measured
indirectly through cavity transmission and in particular in circuit QED.


title:
LOOC UP: Locating and observing optical counterparts to gravitational
  wave bursts

abstract:
  Gravitational wave (GW) bursts (short duration signals) are expected to be
associated with highly energetic astrophysical processes. With such high
energies present, it is likely these astrophysical events will have signatures
in the EM spectrum as well as in gravitational radiation. We have initiated a
program, "Locating and Observing Optical Counterparts to Unmodeled Pulses in
Gravitational Waves" (LOOC UP) to promptly search for counterparts to GW burst
candidates. The proposed method analyzes near real-time data from the
LIGO-Virgo network, and then uses a telescope network to seek optical-transient
counterparts to candidate GW signals. We carried out a pilot study using
S5/VSR1 data from the LIGO-Virgo network to develop methods and software tools
for such a search. We will present the method, with an emphasis on the
potential for such a search to be carried out during the next science run of
LIGO and Virgo, expected to begin in 2009.


title: Localized Gravity on Topological Abelian Higgs Strings

abstract:
  In this work there are proposed several new 6D brane worlds based on exact
topological solutions to the vortex equations for the Abelian Higgs model, with
suitable boundary conditions and symmetry breaking potentials similar to the
mexican hat. Just as happens for RS domain wall brane worlds, it is shown that
the massless mode of linearized gravity is localized in the neighborhood of the
string-vortex solution while there are not massive bounded states. The
correction to the newtonian limit of the effective 4D gravity is calculated.


title:
Prospects for identifying the sources of the Galactic cosmic rays with
  IceCube

abstract:
  We quantitatively address whether IceCube, a kilometer-scale neutrino
detector under construction at the South Pole, can observe neutrinos pointing
back at the accelerators of the Galactic cosmic rays. The photon flux from
candidate sources identified by the Milagro detector in a survey of the TeV sky
is consistent with the flux expected from a typical cosmic-ray generating
supernova remnant interacting with the interstellar medium. We show here that
IceCube can provide incontrovertible evidence of cosmic-ray acceleration in
these sources by detecting neutrinos. We find that the signal is optimally
identified by specializing to events with energies above 30 TeV where the
atmospheric neutrino background is low. We conclude that evidence for a
correlation between the Milagro and IceCube sky maps should be conclusive after
several years.


title:
Matching the circular Wilson loop with dual open string solution at
  1-loop in strong coupling

abstract:
  We compute the 1-loop correction to the effective action for the string
solution in AdS_5 x S^5 dual to the circular Wilson loop. More generically, the
method we use can be applied whenever the two dimensional spectral problem
factorizes, to regularize and define the fluctuation determinants in terms of
solutions of one-dimensional differential equations. A such it can be applied
to non-homogeneous solutions both for open and closed strings and to various
boundary conditions. In the case of the circular Wilson loop, we obtain, for
the 1-loop partition function a result which up to a factor of two matches the
expectation from the exact gauge theory computation. The discrepancy can be
attributed to an overall constant in the string partition function coming from
the normalization of zero modes, which we have not fixed.


title: Staged Self-Assembly:Nanomanufacture of Arbitrary Shapes with O(1) Glues

abstract:
  We introduce staged self-assembly of Wang tiles, where tiles can be added
dynamically in sequence and where intermediate constructions can be stored for
later mixing. This model and its various constraints and performance measures
are motivated by a practical nanofabrication scenario through protein-based
bioengineering. Staging allows us to break through the traditional lower bounds
in tile self-assembly by encoding the shape in the staging algorithm instead of
the tiles. All of our results are based on the practical assumption that only a
constant number of glues, and thus only a constant number of tiles, can be
engineered, as each new glue type requires significant biochemical research and
experiments. Under this assumption, traditional tile self-assembly cannot even
manufacture an n*n square; in contrast, we show how staged assembly enables
manufacture of arbitrary orthogonal shapes in a variety of precise formulations
of the model.


title:
Towards adiabatic waveforms for inspiral into Kerr black holes: II.
  Dynamical sources and generic orbits

abstract:
  This is the second in a series of papers whose aim is to generate
``adiabatic'' gravitational waveforms from the inspiral of stellar-mass compact
objects into massive black holes. In earlier work, we presented an accurate
(2+1)D finite-difference time-domain code to solve the Teukolsky equation,
which evolves curvature perturbations near rotating (Kerr) black holes. The key
new ingredient there was a simple but accurate model of the singular source
term based on a discrete representation of the Dirac-delta function and its
derivatives. Our earlier work was intended as a proof of concept, using simple
circular, equatorial geodesic orbits as a testbed. Such a source is effectively
static, in that the smaller body remains at the same coordinate radius and
orbital inclination over an orbit. (It of course moves through axial angle, but
we separate that degree of freedom from the problem. Our numerical grid has
only radial, polar, and time coordinates.) We now extend the time-domain code
so that it can accommodate dynamic sources that move on a variety of physically
interesting world lines. We validate the code with extensive comparison to
frequency-domain waveforms for cases in which the source moves along generic
(inclined and eccentric) bound geodesic orbits. We also demonstrate the ability
of the time-domain code to accommodate sources moving on interesting
non-geodesic worldlines. We do this by computing the waveform produced by a
test mass following a ``kludged'' inspiral trajectory, made of bound geodesic
segments driven toward merger by an approximate radiation loss formula.


title: Dense and Hot Holographic QCD: Finite Baryonic E Field

abstract:
  We investigate the response of dense and hot holographic QCD (hQCD) to a
static and baryonic electric field E using the chiral model of Sakai and
Sugimoto. Strong fields with E>(\sqrt\lambda M_{KK})^2 free quark pairs,
causing the confined vacuum and matter state to decay. We generalize
Schwinger's QED persistence function to dense hQCD. At high temperature and
density, Ohm's law is derived generalizing a recent result by Karch and
O'Bannon to the chiral case.


title: Infrared QCD

abstract:
  We prove that Nambu-Jona-Lasinio model is an exact description of infrared
QCD deriving it from QCD Lagrangian. The model we obtain is renormalizable and
confining but, taking very small momenta fixes completely all the parameters of
the Nambu-Jona-Lasinio model through those of QCD. The choice of the infrared
propagator is done consistently with recent numerical results from lattice and
Dyson-Schwinger equations for Yang-Mills theory. The model we get coincides,
once the ultraviolet contribution is removed, with the one proposed by
Langfeld, Kettner and Reinhardt [Nucl. Phys. A {\bf 608}, 331 (1996)].


title: Laser-induced Precession of Magnetization in GaMnAs

abstract:
  We report on the photo-induced precession of the ferromagnetically coupled Mn
spins in (Ga,Mn)As, which is observed even with no external magnetic field
applied. We concentrate on various experimental aspects of the time-resolved
magneto-optical Kerr effect (TR-MOKE) technique that can be used to clarify the
origin of the detected signals. We show that the measured data typically
consist of several different contributions, among which only the oscillatory
signal is directly connected with the ferromagnetic order in the sample.


title: Preheating after N-flation

abstract:
  We study preheating in N-flation, assuming the Mar\v{c}enko-Pastur mass
distribution, equal energy initial conditions at the beginning of inflation and
equal axion-matter couplings, where matter is taken to be a single, massless
bosonic field. By numerical analysis we find that preheating via parametric
resonance is suppressed, indicating that the old theory of perturbative
preheating is applicable. While the tensor-to-scalar ratio, the non-Gaussianity
parameters and the scalar spectral index computed for N-flation are similar to
those in single field inflation (at least within an observationally viable
parameter region), our results suggest that the physics of preheating can
differ significantly from the single field case.


title: Advection-Dominated Accretion and the Black Hole Event Horizon

abstract:
  As the luminosity of an accreting black hole drops to a few percent of
Eddington, the spectrum switches from the familiar soft state to a hard state
that is well-described by a distended and tenuous advection-dominated accretion
flow (ADAF). An ADAF is a poor radiator, and the ion temperature can approach
10^{12} K near the center, although the electrons are cooler, with their
temperature typically capped at ~10^{9-11} K. The foundational papers predicted
that the large thermal energy in an ADAF would drive strong winds and jets, as
later observed and also confirmed in computer simulations. Of chief interest,
however, is the accreting gas that races inward. It carries the bulk of the
accretion energy as stored thermal energy, which vanishes without a trace as
the gas passes through the hole's event horizon. One thus expects black holes
in the ADAF regime to be unusually faint. Indeed, this is confirmed by a
comparison of accreting stellar-mass black holes and neutron stars, which
reside in very similar transient X-ray binary systems. The black holes are on
average observed to be fainter by a factor of ~100-1000. The natural
explanation is that a neutron star must radiate the advected thermal energy
from its surface, whereas a black hole can hide the energy behind its event
horizon. The case for an event horizon in Sagittarius A*, which is immune to
caveats on jet outflows and is furthermore independent of the ADAF model, is
especially compelling. These two lines of evidence for event horizons are
impervious to counterarguments that invoke strong gravity or exotic stars.


title:
The Dynamics of Students' Behaviors and Reasoning during Collaborative
  Physics Tutorial Sessions

abstract:
  We investigate the dynamics of student behaviors (posture, gesture, vocal
register, visual focus) and the substance of their reasoning during
collaborative work on inquiry-based physics tutorials. Scherr has characterized
student activity during tutorials as observable clusters of behaviors separated
by sharp transitions, and has argued that these behavioral modes reflect
students' epistemological framing of what they are doing, i.e., their sense of
what is taking place with respect to knowledge. We analyze students' verbal
reasoning during several tutorial sessions using the framework of Russ, and
find a strong correlation between certain behavioral modes and the scientific
quality of students' explanations. We suggest that this is due to a dynamic
coupling of how students behave, how they frame an activity, and how they
reason during that activity. This analysis supports the earlier claims of a
dynamic between behavior and epistemology. We discuss implications for research
and instruction.


title: Discovery of the Dust-Enshrouded Progenitor of SN 2008S with Spitzer

abstract:
  We report the discovery of the progenitor of the recent type IIn SN 2008S in
the nearby galaxy NGC 6946. Surprisingly, it was not found in deep,
pre-explosion optical images of its host galaxy taken with the Large Binocular
Telescope, but only through examination of archival Spitzer mid-IR data. A
source coincident with the SN 2008S position is clearly detected in the 4.5,
5.8, and 8.0 micron IRAC bands, showing no evident variability in the three
years prior to the explosion, yet is undetected at 3.6 and 24 micron. The
distinct presence of ~440 K dust, along with stringent LBT limits on the
optical fluxes, suggests that the progenitor of SN 2008S was engulfed in a
shroud of its own dust. The inferred luminosity of 3.5x10^4 Lsun implies a
modest mass of ~10 Msun. We conclude that objects like SN 2008S are not
exclusively associated with the deaths or outbursts of very massive eta
Carinae-like objects. This conclusion holds based solely on the optical flux
limits even if our identification of the progenitor with the mid-IR source is
incorrect.


title: Radio-loud high-redshift protogalaxy candidates in Bootes

abstract:
  We used the Near Infrared Camera on Keck I to obtain Ks-band images of four
candidate high-redshift radio galaxies selected using optical and radio data in
the NOAO Deep Wide-Field Survey in Bootes. Our targets have 1.4 GHz radio flux
densities greater than 1 mJy, but are undetected in the optical to fainter than
24 Vega mag. Spectral energy distribution fitting suggests that three of these
objects are at z > 3, with radio luminosities near the FR-I / FR-II break. The
other has photometric redshift 1.2, but may in fact be at higher redshift. Two
of the four objects exhibit diffuse morphologies in Ks -band, suggesting that
they are still in the process of forming.


title: The Quasar-frame Velocity Distribution of Narrow CIV Absorbers

abstract:
  We report on a survey for narrow (FWHM < 600 km/s) CIV absorption lines in a
sample of bright quasars at redshifts $1.8 \le z < 2.25$ in the Sloan Digital
Sky Survey. Our main goal is to understand the relationship of narrow CIV
absorbers to quasar outflows and, more generally, to quasar environments. We
determine velocity zero-points using the broad MgII emission line, and then
measure the absorbers' quasar-frame velocity distribution. We examine the
distribution of lines arising in quasar outflows by subtracting model fits to
the contributions from cosmologically intervening absorbers and absorption due
to the quasar host galaxy or cluster environment. We find a substantial number
($\ge 43\pm6$ per cent) of absorbers with REW $> 0.3$ \AA in the velocity range
+750 km/s $\la v \la $ +12000 km/s are intrinsic to the AGN outflow. This
`outflow fraction' peaks near $v=+2000$ km/s with a value of $f_{outflow}
\simeq 0.81 \pm 0.13$. At velocities below $v \approx +2000$ km/s the incidence
of outflowing systems drops, possibly due to geometric effects or to the
over-ionization of gas that is nearer the accretion disk. Furthermore, we find
that outflow-absorbers are on average broader and stronger than
cosmologically-intervening systems. Finally, we find that $\sim 14$ per cent of
the quasars in our sample exhibit narrow, outflowing CIV absorption with REW $>
0.3$\AA, slightly larger than that for broad absorption line systems.


title:
A large population of recently-quenched red-sequence dwarf galaxies in
  the outskirts of the Coma Cluster

abstract:
  We analyse the stellar populations of 75 red-sequence dwarf galaxies in the
Coma cluster, based on high signal-to-noise spectroscopy from the 6.5m MMT. The
sample covers a luminosity range 3-4 magnitudes below M*, in the cluster core
and in a field centred 1 deg to the south-west. We find a strong dependence of
the absorption line strengths with location in the cluster. Galaxies further
from the cluster centre have stronger Balmer lines than inner-field galaxies of
the same luminosity. The magnesium lines are weaker at large radius, while the
iron lines are not correlated with radius. Converting the line strengths into
estimates of stellar age, metallicity and abundance ratios, we find the
gradients are driven by variations in age (>6 sigma significance) and in the
iron abundance Fe/H (~2.7 sigma significance). The light element (Mg, C, N, Ca)
abundances are almost independent of radius. At radius of 0.4-1.3 degree
(~0.3-1.0x the virial radius), dwarf galaxies have ages ~3.8 Gyr on average,
compared to ~6 Gyr near the cluster centre. The outer dwarfs are also ~50% more
iron-enriched, at given luminosity. Our results confirm earlier indications
that the ages of red-sequence galaxies depend on location within clusters, and
in Coma in particular. The exceptionally strong trends found here suggest that
dwarf galaxies are especially susceptible to environmental "quenching", and/or
that the south-west part of Coma is a particularly clear example of recent
quenching in an infalling subcluster.


title:
Slipping friction of an optically and magnetically manipulated
  microsphere rolling at a glass-water interface

abstract:
  The motion of submerged magnetic microspheres rolling at a glass-water
interface has been studied using magnetic rotation and optical tweezers
combined with bright-field microscopy particle tracking techniques. Individual
microspheres of varying surface roughness were magnetically rotated both in and
out of an optical trap to induce rolling, along either plain glass cover slides
or glass cover slides functionalized with polyethylene glycol. It has been
observed that the manipulated microspheres exhibited nonlinear dynamic
rolling-while-slipping motion characterized by two motional regimes: At low
rotational frequencies, the speed of microspheres free-rolling along the
surface increased proportionately with magnetic rotation rate; however, a
further increase in the rotation frequency beyond a certain threshold revealed
a sharp transition to a motion in which the microspheres slipped with respect
to the external magnetic field resulting in decreased rolling speeds. The
effects of surface-microsphere interactions on the position of this threshold
frequency are posed and investigated. Similar experiments with microspheres
rolling while slipping in an optical trap showed congruent results.


title:
The Ratio of Retrograde to Prograde Orbits: A Test for Kuiper Belt
  Binary Formation Theories

abstract:
  With the discovery of Kuiper Belt binaries that have wide separations and
roughly equal masses new theories were proposed to explain their formation. Two
formation scenarios were suggested by Goldreich and collaborators: In the
first, dynamical friction that is generated by a sea of small bodies enables a
transient binary to become bound ($L^2s$ mechanism); in the second, a transient
binary gets bound by an encounter with a third body ($L^3$ mechanism).
  We show that these different binary formation scenarios leave their own
unique signatures in the relative abundance of prograde to retrograde binary
orbits. This signature is due to stable retrograde orbits that exist much
further out in the Hill sphere than prograde orbits. It provides an excellent
opportunity to distinguish between the different binary formation scenarios
observationally.
  We predict that if binary formation proceeded while sub-Hill velocities
prevailed, the vast majority of all comparable mass ratio binaries have
retrograde orbits. This dominance of retrograde binary orbits is a result of
binary formation via the $L^2s$ mechanism, or any other mechanism that
dissipates energy in a smooth and gradual manner. For super-Hill velocities
binary formation proceeds via the $L^3$ mechanism which produces a roughly
equal number of prograde and retrograde binaries. These predictions assume that
subsequent orbital evolution due to dynamical friction and dynamical stirring
of the Kuiper belt did not alter the sense of the binary orbit after formation.


title:
The ACS Virgo Cluster Survey XV. The Formation Efficiencies of Globular
  Clusters in Early-Type Galaxies: The Effects of Mass and Environment

abstract:
  The fraction of stellar mass contained in globular clusters (GCs), also
measured by number as the specific frequency, is a fundamental quantity that
reflects both a galaxy's early star formation and its entire merging history.
We present specific frequencies, luminosities, and mass fractions for the
globular cluster systems of 100 early-type galaxies in the ACS Virgo Cluster
Survey, the largest homogeneous catalog of its kind. We find that 1) GC mass
fractions can be high in both giants and dwarfs, but are universally low in
galaxies with intermediate luminosities. 2) The behavior of specific frequency
across galaxy mass is dominated by the blue GCs. 3) The GC fractions of
low-mass galaxies exhibit a dependence on environment. Nearly all dwarf
galaxies with high GC fractions are within 1 Mpc of the cD galaxy M87,
presenting the first strong evidence that GC formation in dwarfs is biased
toward dense environments. 4) GC formation in central dwarfs is biased because
their stars form earliest and most intensely. Comparisons to the Millennium
Simulation show that central dwarfs have older stellar populations and form
more stars at higher star formation rates (SFRs) and SFR surface densities. The
SFR surface density in simulated dwarfs peaks before the total SFR, naturally
producing GC populations that are older and more metal-poor than the field
stars. 5) Dwarfs within ~40 kpc of the giant ellipticals M87 and M49 are red
and have few or no GCs, suggesting that they have been tidally stripped and
have contributed their GCs to the halos of their giant neighbors. The central
dwarfs with high GC mass fractions are thus likely to be the survivors most
similar to the protogalaxies that assembled the rich M87 globular cluster
system.(Abridged)


abstract:
  Explicit formulae for Weber-Schafheitlin's type integrals with exponent 1 are
derived. The results of these integrals are distributions on R_+.


title:
The high energy semiclassical asymptotics of loci of roots of
  fundamental solutions for polynomial potentials

abstract:
  In the case of polynomial potentials all solutions to 1-D Schroedinger
equation are entire functions totally determined by loci of their roots and
their behaviour at infinity. In this paper a description of the first of the
two properties is given for fundamental solutions for the high complex energy
limit when the energy is quantized or not. In particular due to the fact that
the limit considered is semiclassical it is shown that loci of roots of
fundamental solutions are collected of selected Stokes lines (called
exceptional) specific for the solution considered and are distributed along
these lines in a specific way. A stable asymptotic limit of loci of zeros of
fundamental solutions on their exceptional Stokes lines has island forms and
there are infintely many of such roots islands on exceptional Stokes lines
escaping to infinity and a finite number of them on exceptional Stokes lines
which connect pairs of turning points. The results obtained for asymptotic
roots distributions of fundamental solutions in the semiclassical high
(complex) energy limit are of a general nature for polynomial potentials.


title: A class of variational functionals in conformal geometry

abstract:
  We derive a class of variational functionals which arise naturally in
conformal geometry. In the special case when the Riemannian manifold is locally
conformal flat, the functional coincides with the well studied functional which
is the integration over the manifold of the k-symmetric function of the
Schouten tensor of the metric on the manifold.


title: Strongly Hyperbolic Extensions of the ADM Hamiltonian

abstract:
  The ADM Hamiltonian formulation of general relativity with prescribed lapse
and shift is a weakly hyperbolic system of partial differential equations. In
general weakly hyperbolic systems are not mathematically well posed. For well
posedness, the theory should be reformulated so that the complete system,
evolution equations plus gauge conditions, is (at least) strongly hyperbolic.
Traditionally, reformulation has been carried out at the level of equations of
motion. This typically destroys the variational and Hamiltonian structures of
the theory. Here I show that one can extend the ADM formalism to (i)
incorporate the gauge conditions as dynamical equations and (ii) affect the
hyperbolicity of the complete system, all while maintaining a Hamiltonian
description. The extended ADM formulation is used to obtain a strongly
hyperbolic Hamiltonian description of Einstein's theory that is generally
covariant under spatial diffeomorphisms and time reparametrizations, and has
physical characteristics. The extended Hamiltonian formulation with 1+log
slicing and gamma--driver shift conditions is weakly hyperbolic.


title:
The AMIGA sample of isolated galaxies. VII. Far-infrared and radio
  continuum study of nuclear activity

abstract:
  We present a study of the nuclear activity in a well-defined sample of the
most isolated galaxies in the local Universe traced by their far-infrared (FIR)
and radio continuum emission. We use the well-known radio continuum-FIR
correlation to select radio-excess galaxies that are candidates to host an
active galactic nucleus (AGN), as well as the FIR colours to find obscured AGN
candidates. The existing information on nuclear activity in the V\'eron-Cetty
catalogue and in the NASA Extragalactic Database are also used. A final
catalogue of AGN-candidate galaxies has been produced. It contains 89 AGN
candidates and is publicly available on the AMIGA web page
(http://www.iaa.csic.es/AMIGA.html). At most ~ 1.5 % of the galaxies shows a
radio-excess with respect to the radio-FIR correlation, and this fraction even
goes down to less than 0.8 % after rejection of back/foreground sources. We
find that the fraction of FIR colour selected AGN-candidates is ~ 28 % with a
lower limit of ~ 7 %. A comparison with the results from the literature shows
that the AMIGA sample has the lowest ratio of AGN candidates, both globally and
separated into early and late types. Field galaxies as well as poor cluster and
group environments show intermediate values, while the highest rates of AGN
candidates are found in the central parts of clusters and in pair/merger
dominated samples. We conclude that the environment plays a crucial and direct
role in triggering radio nuclear activity and not only via the
density-morphology relation. Isolated, early-type galaxies show a particularly
low level of activity at radio wavelengths hence constituting the most
nurture-free population of luminous early-type galaxies.


title: The \bar{\partial}_b Neumann problem on noncharacteristic domains

abstract:
  We study the $\bar{\partial}_b$-Neumann problem for domains $\Omega$
contained in a strictly pseudoconvex manifold M^{2n+1} whose boundaries are
noncharacteristic and have defining functions depending solely on the real and
imaginary parts of a single CR function w. When the Kohn Laplacian is a priori
known to have closed range in L^2, we prove sharp regularity and estimates for
solutions. We establish a condition on the boundary which is sufficient for the
Kohn Laplacian to be Fredholm on $L^2_{(0,q)}(\Omega)$ and show that this
condition always holds when M is embedded as a hypersurface in C^{n+1}. We
present examples where the inhomogeneous $\bar{\partial}_b$ equation can always
be solved smoothly up to the boundary on (p,q)-forms with 0<q<n-1.


title:
Statistical Description of a Magnetized Corona above a Turbulent
  Accretion Disk

abstract:
  We present a physics-based statistical theory of a force-free magnetic field
in the corona above a turbulent accretion disk. The field is represented by a
statistical ensemble of loops tied to the disk. Each loop evolves under several
physical processes: Keplerian shear, turbulent random walk of the disk
footpoints, and reconnection with other loops. To build a statistical
description, we introduce the distribution function of loops over their sizes
and construct a kinetic equation that governs its evolution. This loop kinetic
equation is formally analogous to Boltzmann's kinetic equation, with loop-loop
reconnection described by a binary collision integral. A dimensionless
parameter is introduced to scale the (unknown) overall rate of reconnection
relative to Keplerian shear. After solving for the loop distribution function
numerically, we calculate self-consistently the distribution of the mean
magnetic pressure and dissipation rate with height, and the equilibrium shapes
of loops of different sizes. We also compute the energy and torque associated
with a given loop, as well as the total magnetic energy and torque in the
corona. We explore the dependence of these quantities on the reconnection
parameter and find that they can be greatly enhanced if reconnection between
loops is suppressed.


title:
Adaptive boundary conditions for exterior stationary flows in three
  dimensions

abstract:
  Recently there has been an increasing interest for a better understanding of
ultra low Reynolds number flows. In this context we present a new setup which
allows to efficiently solve the stationary incompressible Navier-Stokes
equations in an exterior domain in three dimensions numerically. The main point
is that the necessity to truncate for numerical purposes the exterior domain to
a finite sub-domain leads to the problem of finding so called "artificial
boundary conditions" to replace the conditions at infinity. To solve this
problem we provide a vector filed that describes the leading asymptotic
behavior of the solution at large distances. This vector field depends
explicitly on drag and lift which are determined in a self-consistent way as
part of the solution process. When compared with other numerical schemes the
size of the computational domain that is needed to obtain the hydrodynamic
forces with a given precision is drastically reduced, which in turn leads to an
overall gain in computational efficiency of typically several orders of
magnitude.


title: Instability of large solitary water waves

abstract:
  We consider the linearized instability of 2D irrotational solitary water
waves. The maxima of energy and the travel speed of solitary waves are not
obtained at the highest wave, which has a 120 degree angle at the crest. Under
the assumption of non-existence of secondary bifurcation which is confirmed
numerically, we prove linear instability of solitary waves which are higher
than the wave of maximal energy and lower than the wave of maximal travel
speed. It is also shown that there exist unstable solitary waves approaching
the highest wave. The unstable waves are of large amplitude and therefore this
type of instability can not be captured by the approximate models derived under
small amplitude assumptions. For the proof, we introduce a family of nonlocal
dispersion operators to relate the linear instability problem with the elliptic
nature of solitary waves. A continuity argument with a moving kernel formula is
used to study these dispersion operators to yield the instability criterion.


title: Dynamical Creation of Fractionalized Vortices and Vortex Lattices

abstract:
  We investigate dynamic creation of fractionalized half-quantum vortices in
Bose-Einstein condensates of sodium atoms. Our simulations show that both
individual half-quantum vortices and vortex lattices can be created in rotating
optical traps when additional pulsed magnetic trapping potentials are applied.
We also find that a distinct periodically modulated spin-density-wave spatial
structure is always embedded in square half-quantum vortex lattices; this
structure can be conveniently probed by taking absorption images of
ballistically expanding cold atoms in a Stern-Gerlach field.


title: Hilbert schemes of 8 points

abstract:
  The Hilbert scheme H^d_n of n points in A^d contains an irreducible component
R^d_n which generically represents n distinct points in A^d. We show that when
n is at most 8, the Hilbert scheme H^d_n is reducible if and only if n = 8 and
d >= 4. In the simplest case of reducibility, the component R^4_8 \subset H^4_8
is defined by a single explicit equation which serves as a criterion for
deciding whether a given ideal is a limit of distinct points.
  To understand the components of the Hilbert scheme, we study the closed
subschemes of H_n^d which parametrize those ideals which are homogeneous and
have a fixed Hilbert function. These subschemes are a special case of
multigraded Hilbert schemes, and we describe their components when the colength
is at most 8. In particular, we show that the scheme corresponding to the
Hilbert function (1,3,2,1) is the minimal reducible example.


title:
A precise determination of alpha_s from LEP thrust data using effective
  field theory

abstract:
  Starting from a factorization theorem in Soft-Collinear Effective Theory, the
thrust distribution in e+e- collisions is calculated including resummation of
the next-to-next-to-next-to leading logarithms. This is a significant
improvement over previous calculations which were only valid to next-to-leading
logarithmic order. The fixed-order expansion of the resummed result approaches
the exact fixed-order distribution towards the kinematic endpoint. This close
agreement provides a verification of both the effective field theory expression
and recently completed next-to-next-to-leading fixed order event shapes. The
resummed distribution is then matched to fixed order, resulting in a
distribution valid over a large range of thrust. A fit to ALEPH and OPAL data
from LEP 1 and LEP 2 produces alpha_s(m_Z)= 0.1172 +/- 0.0010 +/- 0.0008
+/-0.0012 +/- 0.0012, where the uncertainties are respectively statistical,
systematic, hadronic, and perturbative. This is one of the world's most precise
extractions of alpha_s to date.


title: CP-violation in Compton scattering

abstract:
  I consider Compton scattering off the nucleon in the presence of $CP$
violation. I construct the Compton tensor which possesses these features and
consider low energy expansion (LEX) of the corresponding amplitudes. It allows
to separate out the Born contribution which only depends on the static
properties of the nucleon, such as the electric charge, the mass, the magnetic
moment, and the electric dipole moment (EDM). I introduce new structure
constants, the $T$-odd nucleon polarizabilities which parametrize the unknown
non-Born part. These constants describe the response of the $T$-violating
content of the nucleon to the external quasistatic electromagnetic field. As an
estimate, I provide a HBChPT calculation for these new polarizabilities and
discuss the implications for the experiment.


title:
Center-stabilized Yang-Mills theory: confinement and large $N$ volume
  independence

abstract:
  We examine a double trace deformation of SU(N) Yang-Mills theory which, for
large $N$ and large volume, is equivalent to unmodified Yang-Mills theory up to
$O(1/N^2)$ corrections. In contrast to the unmodified theory, large $N$ volume
independence is valid in the deformed theory down to arbitrarily small volumes.
The double trace deformation prevents the spontaneous breaking of center
symmetry which would otherwise disrupt large $N$ volume independence in small
volumes. For small values of $N$, if the theory is formulated on $\R^3 \times
S^1$ with a sufficiently small compactification size $L$, then an analytic
treatment of the non-perturbative dynamics of the deformed theory is possible.
In this regime, we show that the deformed Yang-Mills theory has a mass gap and
exhibits linear confinement. Increasing the circumference $L$ or number of
colors $N$ decreases the separation of scales on which the analytic treatment
relies. However, there are no order parameters which distinguish the small and
large radius regimes. Consequently, for small $N$ the deformed theory provides
a novel example of a locally four-dimensional pure gauge theory in which one
has analytic control over confinement, while for large $N$ it provides a simple
fully reduced model for Yang-Mills theory. The construction is easily
generalized to QCD and other QCD-like theories.


title: Secret key distillation from shielded two-qubit states

abstract:
  The quantum states corresponding to a secret key are characterized using the
so-called private states, where the key part consisting of a secret key is
shielded by the additional systems. Based on the construction, it was shown
that a secret key can be distilled from bound entangled states. In this work, I
consider the shielded two-qubit states in a key-distillation scenario and
derive the conditions under which a secret key can be distilled using the
recurrence protocol or the two-way classical distillation, advantage
distillation together with one-way postprocessing. From the security
conditions, it is shown that a secret key can be distilled from bound entangled
states in a much wider range. In addition, I consider the case that in which
white noise is added to quantum states and show that the classical distillation
protocol still works despite a certain amount of noise although the recurrence
protocol does not.


title:
Superlattice Patterns in the Complex Ginzburg-Landau Equation with
  Multi-Resonant Forcing

abstract:
  Motivated by the rich variety of complex patterns observed on the surface of
fluid layers that are vibrated at multiple frequencies, we investigate the
effect of such resonant forcing on systems undergoing a Hopf bifurcation to
spatially homogeneous oscillations. We use an extension of the complex
Ginzburg-Landau equation that systematically captures weak forcing functions
with a spectrum consisting of frequencies close to the 1:1-, the 1:2-, and the
1:3-resonance. By slowly modulating the amplitude of the 1:2-forcing component
we render the bifurcation to subharmonic patterns supercritical despite the
quadratic interaction introduced by the 1:3-forcing. Our weakly nonlinear
analysis shows that quite generally the forcing function can be tuned such that
resonant triad interactions with weakly damped modes stabilize subharmonic
patterns comprised of four or five Fourier modes, which are similar to
quasi-patterns with 4-fold and 5-fold rotational symmetry, respectively. Using
direct simulations of the extended complex Ginzburg-Landau equation we confirm
our weakly nonlinear analysis. In simulations domains of different complex
patterns compete with each other on a slow time scale. As expected from energy
arguments, with increasing strength of the triad interaction the more complex
patterns eventually win out against the simpler patterns. We characterize these
ordering dynamics using the spectral entropy of the patterns. For system
parameters reported for experiments on the oscillatory Belousov-Zhabotinsky
reaction we explicitly show that the forcing parameters can be tuned such that
4-mode patterns are the preferred patterns.


title:
Can pulsational instabilities impact a massive star's rotational
  evolution?

abstract:
  We investigate whether angular momentum transport due to unstable pulsation
modes can play a significant role in the rotational evolution of massive stars.
We find that these modes can redistribute appreciable angular momentum, and
moreover trigger shear-instability mixing in the molecular weight gradient zone
adjacent to stellar cores, with significant evolutionary impact.


title: Quantum Energy Teleportation in Spin Chain Systems

abstract:
  We propose a protocol for quantum energy teleportation which transports
energy in spin chains to distant sites only by local operations and classical
communication. By utilizing ground-state entanglement and notion of negative
energy density region, energy is teleported without breaking any physical laws
including causality and local energy conservation. Because not excited physical
entity but classical information is transported in the protocol, the
dissipation rate of energy in transport is expected to be strongly suppressed.


title: The limits of filopodium stability

abstract:
  Filopodia are long, finger-like membrane tubes supported by cytoskeletal
filaments. Their shape is determined by the stiffness of the actin filament
bundles found inside them and by the interplay between the surface tension and
bending rigidity of the membrane. Although one might expect the Euler buckling
instability to limit the length of filopodia, we show through simple energetic
considerations that this is in general not the case. By further analyzing the
statics of filaments inside membrane tubes, and through computer simulations
that capture membrane and filament fluctuations, we show under which conditions
filopodia of arbitrary lengths are stable. We discuss several in vitro
experiments where this kind of stability has already been observed.
Furthermore, we predict that the filaments in long, stable filopodia adopt a
helical shape.

categories: q-bio.SC cond-mat.soft physics.bio-ph q-bio.CB


title:
X-ray Polarization Signatures of Compton Scattering in Magnetic
  Cataclysmic Variables

abstract:
  Compton scattering within the accretion column of magnetic cataclysmic
variables (mCVs) can induce a net polarization in the X-ray emission. We
investigate this process using Monte Carlo simulations and find that
significant polarization can arise as a result of the stratified flow structure
in the shock-ionized column. We find that the degree of linear polarization can
reach levels up to ~8% for systems with high accretion rates and low
white-dwarf masses, when viewed at large inclination angles with respect to the
accretion column axis. These levels are substantially higher than previously
predicted estimates using an accretion column model with uniform density and
temperature. We also find that for systems with a relatively low-mass white
dwarf accreting at a high accretion rate, the polarization properties may be
insensitive to the magnetic field, since most of the scattering occurs at the
base of the accretion column where the density structure is determined mainly
by bremsstrahlung cooling instead of cyclotron cooling.


title:
Extra-Large Remnant Recoil Velocities and Spins from
  Near-Extremal-Bowen-York-Spin Black-Hole Binaries

abstract:
  We evolve equal-mass, equal-spin black-hole binaries with specific spins of
a/mH 0.925, the highest spins simulated thus far and nearly the largest
possible for Bowen-York black holes, in a set of configurations with the spins
counter-aligned and pointing in the orbital plane, which maximizes the recoil
velocities of the merger remnant, as well as a configuration where the two
spins point in the same direction as the orbital angular momentum, which
maximizes the orbital hang-up effect and remnant spin. The coordinate radii of
the individual apparent horizons in these cases are very small and the
simulations require very high central resolutions (h ~ M/320). We find that
these highly spinning holes reach a maximum recoil velocity of ~3300 km/s (the
largest simulated so far) and, for the hangup configuration, a remnant spin of
a/mH 0.922. These results are consistent with our previous predictions for the
maximum recoil velocity of ~4000 km/s and remnant spin; the latter reinforcing
the prediction that cosmic censorship is not violated by merging
highly-spinning black-hole binaries. We also numerically solve the initial data
for, and evolve, a single maximal-Bowen-York-spin black hole, and confirm that
the 3-metric has an O(1/r^2) singularity at the puncture, rather than the usual
O(1/r^4) singularity seen for non-maximal spins.


title:
Strong spin-orbit coupling effects on the Fermi surface of Sr2RuO4 and
  Sr2RhO4

abstract:
  We present a first-principle study of spin-orbit coupling effects on the
Fermi surface of Sr2RuO4 and Sr2RhO4. For nearly degenerate bands, spin-orbit
coupling leads to a dramatic change of the Fermi surface with respect to
non-relativistic calculations; as evidenced by the comparison with experiments
on Sr2RhO4, it cannot be disregarded. For Sr2RuO4, the Fermi surface
modifications are more subtle but equally dramatic in the detail: spin-orbit
coupling induces a strong momentum dependence, normal to the RuO2 planes, for
both orbital and spin character of the low-energy electronic states. These
findings have profound implications for the understanding of unconventional
superconductivity in Sr2RuO4.


title: Cox rings of degree one del Pezzo surfaces

abstract:
  Let X be a del Pezzo surface of degree one over an algebraically closed field
(of any characteristic), and let Cox(X) be its total coordinate ring. We prove
the missing case of a conjecture of Batyrev and Popov, which states that Cox(X)
is a quadratic algebra. We use a complex of vector spaces whose homology
determines part of the structure of the minimal free Pic(X)-graded resolution
of Cox(X) over a polynomial ring. We show that sufficiently many Betti numbers
of this minimal free resolution vanish to establish the conjecture.


title:
Terascale Physics Opportunities at a High Statistics, High Energy
  Neutrino Scattering Experiment: NuSOnG

abstract:
  This article presents the physics case for a new high-energy, ultra-high
statistics neutrino scattering experiment, NuSOnG (Neutrino Scattering on
Glass). This experiment uses a Tevatron-based neutrino beam to obtain over an
order of magnitude higher statistics than presently available for the purely
weak processes $\nu_{\mu}+e^- \to \nu_{\mu}+ e^-$ and $\nu_{\mu}+ e^- \to \nu_e
+ \mu^-$. A sample of Deep Inelastic Scattering events which is over two orders
of magnitude larger than past samples will also be obtained. As a result,
NuSOnG will be unique among present and planned experiments for its ability to
probe neutrino couplings to Beyond the Standard Model physics. Many Beyond
Standard Model theories physics predict a rich hierarchy of TeV-scale new
states that can correct neutrino cross-sections, through modifications of
$Z\nu\nu$ couplings, tree-level exchanges of new particles such as $Z^\prime$s,
or through loop-level oblique corrections to gauge boson propagators. These
corrections are generic in theories of extra dimensions, extended gauge
symmetries, supersymmetry, and more. The sensitivity of NuSOnG to this new
physics extends beyond 5 TeV mass scales. This article reviews these physics
opportunities.


title: The uniform Korn - Poincar\'e inequality in thin domains

abstract:
  We study the Korn-Poincar\'e inequality: \|u\|_{W^{1,2}(S^h)} < C_h
\|D(u)\|_{L^2(S^h)}, in domains S^h that are shells of small thickness of order
h, around an arbitrary smooth and closed hypersurface S in R^n. By D(u) we
denote the symmetric part of the gradient \nabla u, and we assume the
tangential boundary conditions: u\vec n^h = 0 on \partial S^h. We prove that
C_h remains uniformly bounded as h tends to 0, for vector fields u in any
family of cones (with angle <\pi/2, uniform in h) around the orthogonal
complement of extensions of Killing vector fields on S. We also show that this
condition is optimal, as in turn every Killing field admits a family of
extensions u^h, for which the ratio: \|u^h\|_{W^{1,2}(S^h)} /
\|D(u^h)\|_{L^2(S^h)} blows up as h tends to 0, even if the domains S^h are not
rotationally symmetric.


title:
Tests for Standard Accretion Disk Models by Variability in Active
  Galactic Nuclei

abstract:
  In this paper, standard accretion disk models of AGNs are tested using light
curves of 26 objects well observed for reverberation mapping. Time scales of
variations are estimated by the most common definition of the variability time
scale and the zero-crossing time of the autocorrelation function of the optical
light curves for each source. The measured time scales of variations by the two
methods are consistent with each other. If the typical value of the viscosity
parameter $\alpha \sim 0.1$ is adopted, the measured optical variability time
scales are most close to the thermal time scales of the standard disks. If
$\alpha$ is allowed to range from $\sim 0.03$ to $\sim 0.2$, the measured time
scales are consistent with the thermal time scales of the standard disks. There
is a linear relation between the measured variability time scales and black
hole masses, and this linear relation is qualitatively consistent with
expectation of the standard accretion disk models. The time lags measured by
the ZDCF between different bands are on the order of days. The measured time
lags of NGC 4151 and NGC 7469 are marginally consistent with the time lags
estimated in the case of continuum thermal reprocessing for the standard
accretion disk models. However, the measured time lags of NGC 5548 and Fairall
9 are unlikely to be the case of continuum thermal reprocessing. Our results
are unlikely to be inconsistent with or are likely to be conditionally in favor
of the standard accretion disk models of AGNs.


title: The Mid-Infrared Properties of X-ray Sources

abstract:
  We combine the results of the Spitzer IRAC Shallow Survey and the Chandra
XBootes Survey of the 8.5 square degrees Bootes field of the NOAO Deep Wide-
Field Survey to produce the largest comparison of mid-IR and X-ray sources to
date. The comparison is limited to sources with X-ray fluxes >8x10-15 erg
cm-2s-1 in the 0.5-7.0 keV range and mid-IR sources with 3.6 um fluxes brighter
than 18.4 mag (12.3 uJy). In this most sensitive IRAC band, 85% of the 3086
X-ray sources have mid-IR counterparts at an 80% confidence level based on a
Bayesian matching technique. Only 2.5% of the sample have no IRAC counterpart
at all based on visual inspection. Even for a smaller but a significantly
deeper Chandra survey in the same field, the IRAC Shallow Survey recovers most
of the X-ray sources. A majority (65%) of the Chandra sources detected in all
four IRAC bands occupy a well-defined region of IRAC [3.6] - [4.5] vs [5.8] -
[8.0] color-color space. These X-ray sources are likely infrared luminous,
unobscured type I AGN with little mid-infrared flux contributed by the AGN host
galaxy. Of the remaining Chandra sources, most are lower luminosity type I and
type II AGN whose mid-IR emission is dominated by the host galaxy, while
approximately 5% are either Galactic stars or very local galaxies.


title:
Shell theories arising as low energy \Gamma-limit of 3d nonlinear
  elasticity

abstract:
  We discuss the limiting behavior (using the notion of \Gamma-limit) of the 3d
nonlinear elasticity for thin shells around an arbitrary smooth 2d surface. In
particular, under the assumption that the elastic energy of deformations scales
like h^4 (where h is the thickness of a shell), we derive a limiting theory
which is a generalization of the von K\'arm\'an theory for plates.


title: Stochastic Hard-Sphere Dynamics for Hydrodynamics of Non-Ideal Fluids

abstract:
  A novel stochastic fluid model is proposed with non-ideal structure factor
consistent with compressibility, and adjustable transport coefficients. This
Stochastic Hard Sphere Dynamics (SHSD) algorithm is a modification of the
Direct Simulation Monte Carlo (DSMC) algorithm and has several computational
advantages over event-driven hard-sphere molecular dynamics. Surprisingly, SHSD
results in an equation of state and pair correlation function identical to that
of a deterministic Hamiltonian system of penetrable spheres interacting with
linear core pair potentials. The fluctuating hydrodynamic behavior of the SHSD
fluid is verified for the Brownian motion of a nano-particle suspended in a
compressible solvent.


title:
A trajectory approach to two-state kinetics of single particles on
  sculpted energy landscapes

abstract:
  We study the trajectories of a single colloidal particle as it hops between
two energy wells A and B, which are sculpted using adjacent optical traps by
controlling their respective power levels and separation. Whereas the dynamical
behaviors of such systems are often treated by master-equation methods that
focus on particles as actors, we analyze them here instead using a
trajectory-based variational method called Maximum Caliber, which utilizes a
dynamical partition function. We show that the Caliber strategy accurately
predicts the full dynamics that we observe in the experiments: from the
observed averages, it predicts second and third moments and covariances, with
no free parameters. The covariances are the dynamical equivalents of
Maxwell-like equilibrium reciprocal relations and Onsager-like dynamical
relations. In short, this work describes an experimental model system for
exploring full trajectory distributions in one-particle two-state systems, and
it validates the Caliber approach as a useful way to understand
trajectory-based dynamical distribution functions in this system.


title: Finite epidemic thresholds in fractal scale-free `large-world' networks

abstract:
  It is generally accepted that scale-free networks is prone to epidemic
spreading allowing the onset of large epidemics whatever the spreading rate of
the infection. In the paper, we show that disease propagation may be suppressed
in particular fractal scale-free networks. We first study analytically the
topological characteristics of a network model and show that it is
simultaneously scale-free, highly clustered, "large-world", fractal and
disassortative. Any previous model does not have all the properties as the one
under consideration. Then, by using the renormalization group technique we
analyze the dynamic susceptible-infected-removed (SIR) model for spreading of
infections. Interestingly, we find the existence of an epidemic threshold, as
compared to the usual epidemic behavior without a finite threshold in
uncorrelated scale-free networks. This phenomenon indicates that degree
distribution of scale-free networks does not suffice to characterize the
epidemic dynamics on top of them. Our results may shed light in the
understanding of the epidemics and other spreading phenomena on real-life
networks with similar structural features as the considered model.


title:
Q-systems as cluster algebras II: Cartan matrix of finite type and the
  polynomial property

abstract:
  We define the cluster algebra associated with the Q-system for the
Kirillov-Reshetikhin characters of the quantum affine algebra $U_q(\hat{\g})$
for any simple Lie algebra g, generalizing the simply-laced case treated in
[Kedem 2007]. We describe some special properties of this cluster algebra, and
explain its relation to the deformed Q-systems which appeared on our proof of
the combinatorial-KR conjecture. We prove that the polynomiality of the cluster
variables in terms of the ``initial cluster seeds'', including solutions of the
Q-system, is a consequence of the Laurent phenomenon and the boundary
conditions. We also give a formulation of both Q-systems and generalized
T-systems as cluster algebras with coefficients. This provides a proof of the
polynomiality of solutions of generalized T-systems with appropriate boundary
conditions.


title: Maximaland Primitive Elements in Baby Verma Modules for Type $B_2$

abstract:
  The purpose of this paper is to find maximal and primitive elements of baby
Verma modules for a quantum group of type $B_2$. As a consequence the
composition factors of the baby Verma modules are determined. Similar approach
can be used to find find maximal and primitive elements of Weyl modules for
type $B_2$.


title: Induced decoherence and entanglement by interacting quantum spin baths

abstract:
  The reduced dynamics of a single or two qubits coupled to an interacting
quantum spin bath modeled by a XXZ spin chain is investigated. By using the
method of time-dependent density matrix renormalization group (t-DMRG), we go
beyond the uniform coupling central spin model and evaluate nonperturbatively
the induced decoherence and entanglement. It is shown that both decoherence and
entanglement strongly depend on the phase of the underlying spin bath. We show
that in general, spin baths can induce entanglement for an initially
disentangled pair of qubits. Furthermore, when the spin bath is in the
ferromagnetic phase, because qubits directly couple to the order parameter, the
reduced dynamics shows oscillatory type behavior. On the other hand, only for
paramagnetic and antiferromagnetic phases, initially entangled states suffer
from the entanglement sudden death. By calculating concurrence, the finite
disentanglement time is mapped out for all phases in the phase diagram of the
spin bath.


title: Convergence of adaptive finite element methods for eigenvalue problems

abstract:
  In this article we prove convergence of adaptive finite element methods for
second order elliptic eigenvalue problems. We consider Lagrange finite elements
of any degree and prove convergence for simple as well as multiple eigenvalues
under a minimal refinement of marked elements, for all reasonable marking
strategies, and starting from any initial triangulation.


title:
59Co, 23Na, and 1H NMR Studies of Double-Layer Hydrated Superconductors
  NaxCoO2-yH2O

abstract:
  We present our NMR studies of double-layer hydrated cobalt oxides
NaxCoO2-yH2O (x ~ 0.35, y ~ 1.3) with various Tc = 0 - 4.8 K and magnetic
transition temperatures. High-resolution $^{1}$H NMR spectrum served as an
evidence for the existence of H$_{3}$O$^{+}$ oxonium ions. $^{23}$Na nuclear
spin-lattice relaxation rates served to detect local field fluctuations
sensitive to Tc. $^{59}$Co nuclear quadrupole resonance (NQR) spectra served to
classify the various Tc samples. From the classification by $^{59}$Co NQR
frequency, the double-layer hydrated compounds were found to have two
superconducting phases closely located to a magnetic phase. In the normal state
and at a magnetic field in the $ab$-plane, two $^{59}$Co NMR signals with
different Knight shifts and different $^{59}$Co nuclear spin-lattice relaxation
times $^{59}T_{1}$ were observed. The two $^{59}$Co NMR signals suggest
magnetic disproportionation of two Co sites or in-plane (XY) anisotropy of a
single Co site. Non Korringa behavior and power law behavior in zero-field NQR
1/$^{59}T_{1}$ above and below Tc suggest non-Fermi liquid and unconventional
superconductivity.


title: Plant-Mycorrhiza Percent Infection as Evidence of Coupled Metabolism

abstract:
  A common feature of mycorrhizal observation is the growth of the infection on
the plant root as a percent of the infected root or root tip length. Often,
this is measured as a logistic curve with an eventual, though usually
transient, plateau. It is shown in this paper that the periods of stable
percent infection in the mycorrhizal growth cycle correspond to periods where
both the plant and mycorrhiza growth rates and likely metabolism are tightly
coupled.


title:
Correlated electron-phonon transport from molecular dynamics with
  quantum baths

abstract:
  Based on generalized quantum Langevin equations for the tight-binding wave
function amplitudes and lattice displacements, electron and phonon quantum
transport are obtained exactly using molecular dynamics (MD) in the ballistic
regime. The electron-phonon interactions can be handled with a quasi-classical
approximation. Both charge and energy transport and their interplay can be
studied. We compare the MD results with that of a fully quantum mechanical
nonequilibrium Green's function (NEGF) approach for the electron currents. We
find a ballistic to diffusive transition of the electron conduction in one
dimensional chains as the chain length increases.


title:
Deformation around neutron-rich Cr isotopes in axially symmetric
  Skyrme-Hatree-Fock-Bogoliubov method

abstract:
  We analyse deformation mechanism in neutron-rich Cr, Fe and Ti isotopes with
N=32-44 by means of a Skyrme-Hartree-Fock-Bogoliubov mean-field code employing
a two-dimensional mesh representation in the cylindrical coordinate system.
Evaluating systematically the quadrupole deformation energy, we show that the
Skyrme parameter set SkM* gives a quadrupole instability around the neutron
number N$\sim$38-42 in Cr isotopes, where the deformation energy curve suggests
a transitional behavior with a shallow minimum extending to a large prolate
deformation. Roles of a deformed N=38 gap and the position of the neutron g9/2
orbit are analysed in detail.


title: The Energy Cascade from Warm Dark Matter Decays

abstract:
  We use a set of Monte Carlo simulations to follow the cascade produced by a
primary electron of energy E_in in the intergalactic medium. We choose
E_in=3-10 keV as expected from the decay of one of the most popular Warm Dark
Matter (WDM) candidates, sterile neutrinos. Our simulation takes into account
processes previously neglected such as free-free interactions with ions and
recombinations and uses the best available cross sections for collisional
ionizations and excitations with H and He and for electron-electron collisions.
We precisely derive the fraction of the primary electron energy that heats the
gas, ionizes atoms and produces line and continuum photons as a function of the
ionization fraction. Handy fitting formulae for all the above energy
depositions are provided. By keeping track of the individual photons we can
distinguish between photons in the Ly-alpha resonance and those with energy E <
10.2 eV that do not interact further with gas. This separation is important
because a Ly-alpha background can heat or cool the gas depending on the nature
of the photons, and can have effects on the 21 cm radiation emitted by neutral
H, which will probably become detectable at z > 6 in the near future by the
next generation radio interferometers.


title:
Bifurcation diagrams and critical subsystems of the Kowalevski gyrostat
  in two constant fields

abstract:
  The Kowalevski gyrostat in two constant fields is known as the unique example
of an integrable Hamiltonian system with three degrees of freedom not reducible
to a family of systems in fewer dimensions and still having the clear
mechanical interpretation. The practical explicit integration of this system
can hardly be obtained by the existing techniques. Then the challenging problem
becomes to fulfil the qualitative investigation based on the study of the
Liouville foliation of the phase space. As the first approach to topological
analysis of this system we find the stratified critical set of the momentum
map; this set consists of the trajectories with number of frequencies less than
three. We obtain the equations of the bifurcation diagram in three-dimensional
space. These equations have the form convenient for the classification of the
bifurcation sets induced on 5-dimensional iso-energetic levels.


title: Multifield model for Cosserat media

abstract:
  We construct a two-field higher-order gradient micropolar model for Cosserat
media on the basis of a square lattice of elements with rotational degrees of
freedom. This model includes equations of single-field higher-order gradient
micropolar theory, and additional ones, which allow modelling of short
wavelength phenomena. We demonstrate an example of short wavelength spatially
localized static deformations in a structural system, which could not be
obtained in the classical single-field framework, but which are captured by the
proposed two-field model.


title:
Significant improvement of flux pinning and irreversibility field in
  nano-Carbon doped MgB2 superconductor

abstract:
  We report the synthesis and variation of superconductivity parameters such as
transition temperature Tc, upper critical field Hc, critical current density
Jc, irreversibility field Hirr and flux pinning parameter (Fp) for the MgB2-xCx
system with nano-Carbon doping up to x=0.20. Carbon substitutes successfully on
boron site and results in significant enhancement of Hirr and Jc(H).
Resistivity measurements reveal a continuous decrease in Tc under zero applied
field, while the same improves remarkably at higher fields with an increase in
nano-C content for MgB2-xCx system. The irreversibility field value (Hirr) is
7.6 & 6.6 Tesla at 5 and 10K respectively for the pristine sample, which is
enhanced to 13.4 and 11.0 Tesla for x = .08 sample at same temperatures.
Compared to undoped sample, critical current density (Jc) for the x=0.08
nano-Carbon doped sample is increased by a factor of 24 at 10K at 6 Tesla
field.


title:
Evolution of Dipole-Type Blocking Life Cycles: Analytical Diagnoses and
  Observations

abstract:
  A variable coefficient Korteweg de Vries (VCKdV) system is derived by
considering the time-dependent basic flow and boundary conditions from a
nonlinear, inviscid, nondissipative, and equivalent barotropic vorticity
equation in a beta-plane. One analytical solution obtained from the VCKdV
equation can be successfully used to explain the evolution of atmospheric
dipole-type blocking (DB) life cycles. Analytical diagnoses show that
background mean westerlies have great influence on evolution of DB during its
life cycle. A weak westerly is necessary for blocking development and the
blocking life period shortens, accompanied with the enhanced westerlies. The
shear of the background westerlies also plays an important role in the
evolution of blocking. The cyclonic shear is preferable for the development of
blocking but when the cyclonic shear increases, the intensity of blocking
decreases and the life period of DB becomes shorter. Weak anticyclonic shear
below a critical threshold is also favorable for DB formation. Time-dependent
background westerly (TDW) in the life cycle of DB has some modulations on the
blocking life period and intensity due to the behavior of the mean westerlies.
Statistical analysis regarding the climatological features of observed DB is
also investigated. The Pacific is a preferred region for DB, especially at high
latitudes. These features may associate with the weakest westerlies and the
particular westerly shear structure over the northwestern Pacific.


title: Octonic relativistic quantum mechanics

abstract:
  In this paper we represent the generalization of relativistic quantum
mechanics on the base of eght-component values "octons", generating associative
noncommutative spatial algebra. It is shown that the octonic second-order
equation for the eight-component octonic wave function, obtained from the
Einshtein relation for energy and momentum, describes particles with spin of
1/2. It is established that the octonic wave function of a particle in the
state with defined spin projection has the specific spatial structure in the
form of octonic oscillator with two spatial polarizations: longitudinal linear
and transversal circular. The relations between bispinor and octonic
descriptions of relativistic particles are established. We propose the
eight-component spinors, which are octonic generalisation of two-component
Pauli spinors and four-component Dirac bispinors. It is shown that proposed
eight-component spinors separate the states with different spin projection,
different particle-antiparticle state as well as different polarization of the
octonic oscillator. We demonstrate that in the frames of octonic relativistic
quantum mechanics the second-order equation for octonic wave function can be
reformulated in the form of the system of first-order equations for quantum
fields, which is analogous to the system of Maxwell equations for the
electromagnetic field. It is established that for the special type of wave
functions the second-order equation can be reduced to the single first-order
equation, which is analogous to the Dirac equation. At the same time it is
shown that this first-order equation describes particles, which do not create
quantum fields.


title:
Search for gravitational waves associated with GRB 050915a using the
  Virgo detector

abstract:
  In the framework of the expected association between gamma-ray bursts and
gravitational waves, we present results of an analysis aimed to search for a
burst of gravitational waves in coincidence with gamma-ray burst 050915a. This
was a long duration gamma-ray burst detected by Swift during September 2005,
when the Virgo gravitational wave detector was engaged in a commissioning run
during which the best sensitivity attained in 2005 was exhibited. This offered
the opportunity for Virgo's first search for a gravitational wave signal in
coincidence with a gamma-ray burst. The result of our study is a set of strain
amplitude upper-limits, based on the loudest event approach, for different but
quite general types of burst signal waveforms. The best upper-limit strain
amplitudes we obtain are h_{rss}=O(10^{-20})Hz^{-1/2} around 200-1500 Hz. These
upper-limits allow us to evaluate the level up to which Virgo, when reaching
nominal sensitivity, will be able to constrain the gravitational wave output
associated with a long burst. Moreover, the analysis here presented plays the
role of a prototype, crucial in defining a methodology for gamma-ray burst
triggered searches with Virgo and opening the way for future joint analyses
with LIGO.


title: Modular Forms and Elliptic Genera for ALE Spaces

abstract:
  When we describe string propagation on non-compact or singular Calabi-Yau
manifolds by CFT, continuous as well as discrete representations appear in the
theory. These representations mix in an intricate way under the modular
transformations. In this article, we propose a method of combining discrete and
continuous representations so that the resulting combinations have a simpler
modular behavior and can be used as conformal blocks of the theory. We compute
elliptic genera of ALE spaces and obtain results which agree with those
suggested from the decompactification of K3 surface. Consistency of our
approach is assured by some remarkable identity of theta functions.
  We include in the appendix some new materials on the representation theory of
${\cal N}=4$ superconformal algebra.


title: Thread algebra for poly-threading

abstract:
  Threads as considered in basic thread algebra are primarily looked upon as
behaviours exhibited by sequential programs on execution. It is a fact of life
that sequential programs are often fragmented. Consequently, fragmented program
behaviours are frequently found. In this paper, we consider this phenomenon. We
extend basic thread algebra with the barest mechanism for sequencing of threads
that are taken for fragments. This mechanism, called poly-threading, supports
both autonomous and non-autonomous thread selection in sequencing. We relate
the resulting theory to the algebraic theory of processes known as ACP and use
it to describe analytic execution architectures suited for fragmented programs.
We also consider the case where the steps of fragmented program behaviours are
interleaved in the ways of non-distributed and distributed multi-threading.


title: A coarse classification of countable abelian groups

abstract:
  We classify up to coarse equivalence all countable abelian groups of finite
torsion free rank. The Q-cohomological dimension and the torsion free rank are
the two invariants that give us such classification. We also prove that any
countable abelian group of finite torsion free rank is coarsely equivalent to
Z^n + H where H is a direct sum (possibly infinite) of cyclic groups. A partial
generalization to countable abelian groups of the Gromov rigidity theorem for
abelian groups is shown.


title: Finite Gluon Fusion Amplitude in the Gauge-Higgs Unification

abstract:
  We show that the gluon fusion amplitude in the gauge-Higgs unification
scenario is finite in any dimension regardless of its nonrenormalizability.
This result is supported by the fact that the local operator describing the
gluon fusion process is forbidden by the higher dimensional gauge invariance.
We explicitly calculate the gluon fusion amplitude in an arbitrary dimensional
gauge-Higgs unification model and indeed obtain the finite result.


title: Naturalness and Electro-weak Symmetry Breaking

abstract:
  The Principle of Naturalness of small parameters of a theory is reviewed.
While quantum field theories constructed from gauge fields and fermions only
are natural, those containing elementary scalar fields are not. In particular
the Higgs boson mass in the Standard Model of electro-weak forces is not stable
against radiative corrections. Two old canonical solutions of this problem are:
(i) where the Higgs boson is a fermion-antifermion composite (technicolour
solution) or otherwise (ii) we need supersymmetry to protect the mass of
elementary Higgs boson from possible large radiative corrections. In recent
years some other mechanisms for electroweak symmetry breaking have been under
intense investigation. These include the little Higgs models and the
gauge-Higgs unification models where the Higgs boson is the zero mode of the
extra-dimensional component of a higher dimensional gauge field. Naturalness
issues of such models are also briefly reviewed.


title: Climate Prediction through Statistical Methods

abstract:
  Climate change is a reality of today. Paleoclimatic proxies and climate
predictions based on coupled atmosphere-ocean general circulation models
provide us with temperature data. Using Detrended Fluctuation Analysis, we are
investigating the statistical connection between the climate types of the
present and these local temperatures. We are relating this issue to some
well-known historic climate shifts. Our main result is that the temperature
fluctuations with or without a temperature scale attached to them, can be used
to classify climates in the absence of other indicators such as pan evaporation
and precipitation.


title: The Blind Watchmaker Network: Scale-freeness and Evolution

abstract:
  It is suggested that the degree distribution for networks of the
cell-metabolism for simple organisms reflects an ubiquitous randomness. This
implies that natural selection has exerted no or very little pressure on the
network degree distribution during evolution. The corresponding random network,
here termed the blind watchmaker network has a power-law degree distribution
with an exponent gamma >= 2. It is random with respect to a complete set of
network states characterized by a description of which links are attached to a
node as well as a time-ordering of these links. No a priory assumption of any
growth mechanism or evolution process is made. It is found that the degree
distribution of the blind watchmaker network agrees very precisely with that of
the metabolic networks. This implies that the evolutionary pathway of the
cell-metabolism, when projected onto a metabolic network representation, has
remained statistically random with respect to a complete set of network states.
This suggests that even a biological system, which due to natural selection has
developed an enormous specificity like the cellular metabolism, nevertheless
can, at the same time, display well defined characteristics emanating from the
ubiquitous inherent random element of Darwinian evolution. The fact that also
completely random networks may have scale-free node distributions gives a new
perspective on the origin of scale-free networks in general.


title: Some results on cosymplectic manifolds

abstract:
  We obtain a generalization of the Kodaira-Morrow stability theorem for
cosymplectic structures. We investigate cosymplectic geometry on Lie groups and
on their compact quotients by uniform discrete subgroups. In this way we show
that a compact solvmanifold admits a cosymplectic structure if and only if it
is a finite quotient of a torus.


title:
The Chemical Evolution of Dwarf Spheroidal Galaxies: Dissecting the
  Inner Regions and their Stellar Populations

abstract:
  Using 3-dimensional hydrodynamical simulations of isolated dwarf spheroidal
galaxies (dSphs), we undertake an analysis of the chemical properties of their
inner regions, identifying the respective roles played by Type Ia (SNe Ia) and
Type II (SNe II) supernovae. The effect of inhomogeneous pollution from SNe Ia
is shown to be prominent within two core radii, with the stars forming therein
amounting to ~20% of the total. These stars are relatively iron-rich and
alpha-element-depleted compared to the stars forming in the rest of the galaxy.
At odds with the projected stellar velocity dispersion radial profile, the
actual 3-dimensional one shows a depression in the central region, where the
most metal-rich (ie. [Fe/H]-rich) stars are partly segregated. This naturally
results in two different stellar populations, with an anti-correlation between
[Fe/H] and velocity dispersion, in the same sense as that observed in the
Sculptor and Fornax dSphs. Because the most iron-rich stars in our model are
also the most alpha-depleted, a natural prediction and test of our model is
that the same radial segregation effects should exist between [alpha/Fe] and
velocity dispersion.


title: Thomas-Fermi model yields condensed phase of molecular metallic oxygen

abstract:
  Calculations, performed in Thomas-Fermi approximation, show that the energy
of a condensed phase of molecular metallic oxygen is lower by 496 kJ/mol than
that of an insulator oxygen phase. The insulator phase is separated from a
metallic one by energetic barrier of 1165 kJ/mol. This barrier could be
overcome by means of electromagnetic irradiation with quantum energy of 12.071
eV or a bit higher. During such a transition the amount of energy equal to 496
kJ/mol is released. It should be extracted from a sample to secure the
existence of a metallic phase.


title: Lie Symmetries and Solutions of KdV Equation

abstract:
  Symmetries of a differential equations is one of the most important concepts
in theory of differential equations and physics. One of the most prominent
equations is KdV (Kortwege-de Vries) equation with application in shallow water
theory. In this paper we are going to explain a particular method for finding
symmetries of KdV equation, which is called Harrison method. Our tools in this
method are Lie derivatives and differential forms, which will be discussed in
the first section more precisely. In second chapter we will have some analysis
on the solutions of KdV equation and we give a method, which is called first
integral method for finding the solutions of KdV equation.


title:
Seoul National University Bright Quasar Survey in Optical (SNUQSO) I:
  First Phase Observations and Results

abstract:
  We present results from the first phase of the Seoul National University
Bright Quasar Survey in Optical (SNUQSO) as well as its basic observational
setup. Previous and current large-area surveys have been successful in
identifying many quasars, but they could have missed bright quasars due to
their survey design. In order to help complete the census of bright quasars, we
have performed spectroscopic observations of new bright quasar candidates
selected from various methods based on optical colors, near-infrared colors,
radio, and X-ray data. In 2005/2006, we observed 55 bright quasar candidates
using the Bohyunsan Optical Echelle Spectrograph (BOES) on the 1.8 m telescope
at the Bohyunsan Optical Astronomy Observatory in Korea. We identify 14
quasars/Seyferts from our observation, including an optically bright quasar
with i=14.98 mag at z=0.092 (SDSS J003236.59-091026.2). Non-quasar/Seyfert
objects are found to be mostly stars, among which there are five M-type stars
and one cataclysmic variable. Our result shows that there still exist bright
quasars to be discovered. However, at the same time, we conclude that finding
new bright quasars in high Galactic latitude regions is very challenging and
that the existing compilation of optically bright quasars is nearly complete in
the northern hemisphere.


title:
The effect of the noncentral impurity-matrix interaction upon the
  thermal expansion and polyamorphism of solid CO-C60 solutions at low
  temperatures

abstract:
  Orientational glasses with CO molecules occupying 26% and 90% of the
octahedral interstitial sites in the C60 lattice have been investigated by the
dilatometric method in a temperature interval of 2.5 - 23 K. At temperatures 4
- 6 K the glasses undergo a first-order phase transition which is evident from
the hysteresis of the thermal expansion and the maxima in the temperature
dependences of the linear thermal expansion coefficients, and the
thermalization times of the samples. The effect of the noncentral CO-C60
interaction upon the thermal expansion and the phase transition in these
glasses was clarified by comparing the behavior of the properties of the CO-C60
and N2-C60 solutions.


title: Gravitational induction

abstract:
  We study the linear post-Newtonian approximation to general relativity known
as gravitoelectromagnetism (GEM); in particular, we examine the similarities
and differences between GEM and electrodynamics. Notwithstanding some
significant differences between them, we find that a special nonstationary
metric in GEM can be employed to show {\it explicitly} that it is possible to
introduce gravitational induction within GEM in close analogy with Faraday's
law of induction and Lenz's law in electrodynamics. Some of the physical
implications of gravitational induction are briefly discussed.


title:
Contact homology of left-handed stabilizations and plumbing of open
  books

abstract:
  We show that on any closed contact manifold of dimension greater than 1 a
contact structure with vanishing contact homology can be constructed. The basic
idea for the construction comes from Giroux. We use a special open book
decomposition for spheres. The page is the cotangent bundle of a sphere and the
monodromy is given by a left-handed Dehn twist. In the resulting contact
manifold we exhibit a closed Reeb orbit that bounds a single finite energy
plane. As a result, the unit element of the contact homology algebra is exact
and so the contact homology vanishes. This result can be extended to other
contact manifolds by using connected sums. The latter is related to the
plumbing- or 2-Murasugi sum of the contact open books. We shall give a possible
description of this construction and some conjectures about the plumbing
operation.


title: Multiscale Inference for High-Frequency Data

abstract:
  This paper proposes a novel multiscale estimator for the integrated
volatility of an Ito process, in the presence of market microstructure noise
(observation error). The multiscale structure of the observed process is
represented frequency-by-frequency and the concept of the multiscale ratio is
introduced to quantify the bias in the realized integrated volatility due to
the observation error. The multiscale ratio is estimated from a single sample
path, and a frequency-by-frequency bias correction procedure is proposed, which
simultaneously reduces variance. We extend the method to include correlated
observation errors and provide the implied time domain form of the estimation
procedure. The new method is implemented to estimate the integrated volatility
for the Heston and other models, and the improved performance of our method
over existing methods is illustrated by simulation studies.


title: Low frequency m=1 normal mode oscillations of a self-gravitating disc

abstract:
  A continuous system such as a galactic disc is shown to be well approximated
by an N-ring differentially rotating self-gravitating system. Lowest order
(m=1) non-axisymmetric features such as lopsidedness and warps are global in
nature and quite common in the discs of spiral galaxies. Apparently these two
features of the galactic discs have been treated like two completely disjoint
phenomena. The present analysis based on an eigenvalue approach brings out
clearly that these two features are fundamentally similar in nature and they
are shown to be very Low frequency Normal Mode (LNM) oscillations manifested in
different symmetry planes of the galactic disc. Our analysis also show that
these features are actually long-lived oscillating pattern of the N-ring
self-gravitating system.


title:
Magneto-Dielectric phenomena in charge and spin frustrated system of
  layered iron oxide

abstract:
  Dielectric and magnetic phenomena in spin and charge frustrated system RFe2O4
(R is a rare-earth metal ion) are studied. An electronic model for charge, spin
and orbital degrees in a pair of triangular-lattice planes is derived. We
analyze this model by utilizing the mean-field approximation and the
Monte-Carlo simulation in a finite size cluster. A three fold-type charge
ordered structure with charge imbalance between the planes is stabilized in
finite temperatures. This polar charge order is reinforced by spin ordering of
Fe ions. This novel magneto-dielectric phenomenon is caused by spin frustration
and charge-spin coupling in the exchange interaction. We show cross-correlation
effect in magnetic- and electric-field responses. Oxygen deficiency effect as
an impurity effect in a frustrated charge-spin coupled system is also examined.


title:
Efficiency of the centrifugally induced curvature drift instability in
  AGN winds

abstract:
  For studying how the field lines are twisting nearby the light cylinder
surface, which provides the free motion of AGN winds through the mentioned
area, the investigation of the centrifugally driven curvature drift instability
is presented. Studying the dynamics of the relativistic MHD flow close to the
light cylinder surface, by applying a single particle approach based on the
centrifugal acceleration, the dispersion relation of the instability is derived
and analytically solved. Considering the typical values of AGN winds, it is
shown that the time scale of the curvature drift instability is much less than
the accretion process time scale, indicating that the present instability is
very efficient and might strongly influence processes in AGN plasmas.


title:
Asymptotic behaviour of a rapidly rotating fluid with random stationary
  surface stress

abstract:
  The goal of this paper is to describe in mathematical terms the effect on the
ocean circulation of a random stationary wind stress at the surface of the
ocean. In order to avoid singular behaviour, non-resonance hypotheses are
introduced, which ensure that the time frequencies of the wind-stress are
different from that of the Earth rotation. We prove a convergence result for a
three-dimensional Navier-Stokes-Coriolis system in a bounded domain, in the
asymptotic of fast rotation and vanishing vertical viscosity, and we exhibit
some random and stationary boundary layer profiles. At last, an average
equation is derived for the limit system in the case of the non-resonant torus.


title:
Entanglement of superconducting qubits via microwave fields: classical
  and quantum regimes

abstract:
  We study analytically and numerically the problem of two qubits with fixed
coupling irradiated with quantum or classical fields. In the classical case, we
derive an effective Hamiltonian, and construct composite pulse sequences
leading to a CNOT gate. In the quantum case, we show that qubit-qubit-photon
multiparticle entanglement and maximally entangled two-qubit state can be
obtained by driving the system at very low powers (one quanta of excitation).
Our results can be applied to a variety of systems of two superconducting
qubits coupled to resonators.


title:
In-depth analysis of the Naming Game dynamics: the homogeneous mixing
  case

abstract:
  Language emergence and evolution has recently gained growing attention
through multi-agent models and mathematical frameworks to study their behavior.
Here we investigate further the Naming Game, a model able to account for the
emergence of a shared vocabulary of form-meaning associations through
social/cultural learning. Due to the simplicity of both the structure of the
agents and their interaction rules, the dynamics of this model can be analyzed
in great detail using numerical simulations and analytical arguments. This
paper first reviews some existing results and then presents a new overall
understanding.

categories: physics.soc-ph cond-mat.stat-mech cs.GT cs.MA


title: Semicosimplicial DGLAs in deformation theory

abstract:
  We identify Cech cocycles in nonabelian (formal) group cohomology with
Maurer-Cartan elements in a suitable L-infinity algebra. Applications to
deformation theory are described.


title: Bijective counting of plane bipolar orientations and Schnyder woods

abstract:
  A bijection $\Phi$ is presented between plane bipolar orientations with
prescribed numbers of vertices and faces, and non-intersecting triples of
upright lattice paths with prescribed extremities. This yields a combinatorial
proof of the following formula due to R. Baxter for the number $\Theta_{ij}$ of
plane bipolar orientations with $i$ non-polar vertices and $j$ inner faces:
$\Theta_{ij}=2\frac{(i+j)!(i+j+1)!(i+j+2)!}{i!(i+1)!(i+2)!j!(j+1)!(j+2)!}$. In
addition, it is shown that $\Phi$ specializes into the bijection of Bernardi
and Bonichon between Schnyder woods and non-crossing pairs of Dyck words.


title: Thermal orientation of electron spins

abstract:
  It is shown that the spin orientation of free electrons occurs in
low-symmetry semiconductor structures if only the electron gas is driven out of
thermal equilibrium with the crystal lattice. The proposed mechanism of such a
thermal orientation of electron spins is based on spin dependence of the
electron-phonon interaction which tends to restore equilibrium. The microscopic
theory of the effect is developed here for asymmetric (110)-grown quantum wells
where the electron gas heating leads to the spin orientation along the [1-10]
axis in the quantum well plane.


title:
A note on sensitivity of principal component subspaces and the efficient
  detection of influential observations in high dimensions

abstract:
  In this paper we introduce an influence measure based on second order
expansion of the RV and GCD measures for the comparison between unperturbed and
perturbed eigenvectors of a symmetric matrix estimator. Example estimators are
considered to highlight how this measure compliments recent influence analysis.
Importantly, we also show how a sample based version of this measure can be
used to accurately and efficiently detect influential observations in practice.


title: Identification of observables in quantum toboggans

abstract:
  Quantum systems with real energies generated by an apparently non-Hermitian
Hamiltonian may re-acquire the consistent probabilistic interpretation via an
ad hoc metric which specifies the set of observables in the updated Hilbert
space of states. The recipe is extended here to quantum toboggans. In the first
step the tobogganic integration path is rectified and the Schroedinger equation
is given the generalized eigenvalue-problem form. In the second step the
general double-series representation of the eligible metric operators is
derived.


title: The Complexity of Testing Properties of Simple Games

abstract:
  Simple games cover voting systems in which a single alternative, such as a
bill or an amendment, is pitted against the status quo. A simple game or a
yes-no voting system is a set of rules that specifies exactly which collections
of ``yea'' votes yield passage of the issue at hand. A collection of ``yea''
voters forms a winning coalition.
  We are interested on performing a complexity analysis of problems on such
games depending on the game representation. We consider four natural explicit
representations, winning, loosing, minimal winning, and maximal loosing. We
first analyze the computational complexity of obtaining a particular
representation of a simple game from a different one. We show that some cases
this transformation can be done in polynomial time while the others require
exponential time. The second question is classifying the complexity for testing
whether a game is simple or weighted. We show that for the four types of
representation both problem can be solved in polynomial time. Finally, we
provide results on the complexity of testing whether a simple game or a
weighted game is of a special type. In this way, we analyze strongness,
properness, decisiveness and homogeneity, which are desirable properties to be
fulfilled for a simple game.


title: Multi-dimensional sparse time series: feature extraction

abstract:
  We show an analysis of multi-dimensional time series via entropy and
statistical linguistic techniques. We define three markers encoding the
behavior of the series, after it has been translated into a multi-dimensional
symbolic sequence. The leading component and the trend of the series with
respect to a mobile window analysis result from the entropy analysis and label
the dynamical evolution of the series. The diversification formalizes the
differentiation in the use of recurrent patterns, from a Zipf law point of
view. These markers are the starting point of further analysis such as
classification or clustering of large database of multi-dimensional time
series, prediction of future behavior and attribution of new data. We also
present an application to economic data. We deal with measurements of money
investments of some business companies in advertising market for different
media sources.


title:
Quantum error correction may delay, but also cause, entanglement sudden
  death

abstract:
  Dissipation may cause two initially entangled qubits to evolve into a
separable state in a finite time. This behavior is called entanglement sudden
death (ESD). We study to what extent quantum error correction can combat ESD.
We find that in some cases quantum error correction can delay entanglement
sudden death but in other cases quantum error correction may cause ESD for
states that otherwise do not suffer from it. Our analysis also shows that
fidelity may not be the best measure to compare the efficiency of different
error correction codes since the fidelity is not directly coupled to a state's
remaining entanglement.