title: Variations in a Universal Density Profile

abstract:
  Using a newly-developed modeling technique, we present orbit-based dynamical
models of the Carina, Draco, Fornax, Sculptor, and Sextans dwarf spheroidal
(dSph) galaxies. These models calculate the dark matter profiles
non-parametrically without requiring any assumptions to be made about their
profile shapes. By lifting this restriction we discover a host of dark matter
profiles in the dSphs that are different from the typical profiles suggested by
both theorists and observers. However, when we scale these profiles
appropriately and plot them on a common axis they appear to follow an
approximate r^-1 power law with considerable scatter.


title:
Spectral Sum Rules and Magneto-Roton as Emergent Graviton in Fractional
  Quantum Hall Effect

abstract:
  We consider gapped fractional quantum Hall states on the lowest Landau level
when the Coulomb energy is much smaller than the cyclotron energy. We introduce
two spectral densities, \rho_T(\omega) and \bar \rho_T(\omega), which are
proportional to the probabilities of absorption of circularly polarized
gravitons by the quantum Hall system. We prove three sum rules relating these
spectral densities with the shift S, the q^4 coefficient of the static
structure factor S_4, and the high-frequency shear modulus of the ground state
\mu_\infty, which is precisely defined. We confirm an inequality, first
suggested by Haldane, that S_4 is bounded from below by |S-1|/8. The Laughlin
wavefunction saturates this bound, which we argue to imply that systems with
ground state wavefunctions close to Laughlin's absorb gravitons of
predominantly one circular polarization. We consider a nonlinear model where
the sum rules are saturated by a single magneto-roton mode. In this model, the
magneto-roton arises from the mixing between oscillations of an internal metric
and the hydrodynamic motion. Implications for experiments are briefly
discussed.


title: Mapping our Universe in 3D with MITEoR

abstract:
  Mapping our universe in 3D by imaging the redshifted 21 cm line from neutral
hydrogen has the potential to overtake the cosmic microwave background as our
most powerful cosmological probe, because it can map a much larger volume of
our Universe, shedding new light on the epoch of reionization, inflation, dark
matter, dark energy, and neutrino masses. We report on MITEoR, a pathfinder
low-frequency radio interferometer whose goal is to test technologies that
greatly reduce the cost of such 3D mapping for a given sensitivity. MITEoR
accomplishes this by using massive baseline redundancy both to enable automated
precision calibration and to cut the correlator cost scaling from N^2 to NlogN,
where N is the number of antennas. The success of MITEoR with its 64
dual-polarization elements bodes well for the more ambitious HERA project,
which would incorporate many identical or similar technologies using an order
of magnitude more antennas, each with dramatically larger collecting area.


title: A note on M2-branes in opposite charge

abstract:
  The flux singularity that arise when branes are put in an oppositely charged
background is a wildly discussed issue and in this paper the problem is
investigated further. New AdS world volume (anti-)M2-brane solutions are
constructed by placing the brane in a background where the charge dissolved in
the flux is opposite that of the brane. A topological obstruction is derived to
show how the singularity develops during localisation of this solution and any
similarly constructed solution. Furthermore the singularity is shown not to be
possible to hide behind a horizon, which would have given credence to a
possible M-theory resolution.


title:
A Robust Determination of Milky Way Satellite Properties using
  Hierarchical Mass Modeling

abstract:
  We introduce a new methodology to robustly determine the mass profile, as
well as the overall distribution, of Local Group satellite galaxies.
Specifically we employ a statistical multilevel modelling technique, Bayesian
hierarchical modelling, to simultaneously constrain the properties of
individual Local Group Milky Way satellite galaxies and the characteristics of
the Milky Way satellite population. We show that this methodology reduces the
uncertainty in individual dwarf galaxy mass measurements up to a factor of a
few for the faintest galaxies. We find that the distribution of Milky Way
satellites inferred by this analysis, with the exception of the apparent lack
of high-mass haloes, is consistent with the Lambda cold dark matter
(Lambda-CDM) paradigm. In particular we find that both the measured
relationship between the maximum circular velocity and the radius at this
velocity, as well as the inferred relationship between the mass within 300 pc
and luminosity, match the values predicted by Lambda-CDM simulations for halos
with maximum circular velocities below 20 km/sec. Perhaps more striking is that
this analysis seems to suggest a more cusped "average" halo shape that is
shared by these galaxies. While this study reconciles many of the observed
properties of the Milky Way satellite distribution with that of Lambda-CDM
simulations, we find that there is still a deficit of satellites with maximum
circular velocities of 20-40 km/sec.


title: Do gravitational lens galaxies have an excess of luminous substructure?

abstract:
  Strong gravitational lensing can be used to directly measure the mass
function of their satellites, thus testing one of the fundamental predictions
of cold dark matter cosmological models. Given the importance of this test it
is essential to ensure that galaxies acting as strong lenses have dark and
luminous satellites which are representative of the overall galaxy population.
We address this issue by measuring the number and spatial distribution of
luminous satellites in ACS imaging around lens galaxies from the Sloan Lens
Advanced Camera for Surveys (SLACS) lenses, and comparing them with the
satellite population in ACS imaging of non lens galaxies selected from COSMOS,
which has similar depth and resolution to the ACS images of SLACS lenses. In
order to compare the samples of lens and non lens galaxies, which have
intrinsically different stellar mass distributions, we measure, for the first
time, the number of satellites per host as a continuous function of host
stellar mass for both populations. We find that the number of satellites as a
function of host stellar mass, as well as the spatial distribution are
consistent between the samples. Using these results, we predict the number of
satellites we would expect to find around a subset of the Cosmic Lens All Sky
Survey (CLASS) lenses, and find a result consistent with the the number
observed by Jackson et al. 2010. Thus we conclude that within our measurement
uncertainties there is no significant difference in the satellite populations
of lens and non lens galaxies.


title: Noisy Interactive Quantum Communication

abstract:
  We study the problem of simulating protocols in a quantum communication
setting over noisy channels. This problem falls at the intersection of quantum
information theory and quantum communication complexity, and it will be of
importance for eventual real-world applications of interactive quantum
protocols, which can be proved to have exponentially lower communication costs
than their classical counterparts for some problems. These are the first
results concerning the quantum version of this problem, originally studied by
Schulman in a classical setting (FOCS '92, STOC '93). We simulate a length $N$
quantum communication protocol by a length $O(N)$ protocol with arbitrarily
small error. Under adversarial noise, our strategy can withstand, for
arbitrarily small $\epsilon > 0$, error rates as high as $1/2 -\epsilon$ when
parties pre-share perfect entanglement, but the classical channel is noisy. We
show that this is optimal. We provide extension of these results in several
other models of communication, including when also the entanglement is noisy,
and when there is no pre-shared entanglement but communication is quantum and
noisy. We also study the case of random noise, for which we provide simulation
protocols with positive communication rates and no pre-shared entanglement over
some quantum channels with quantum capacity $C_Q=0$, proving that $C_Q$ is in
general not the right characterization of a channel's capacity for interactive
quantum communication. Our results are stated for a general quantum
communication protocol in which Alice and Bob collaborate, and these results
hold in particular in the quantum communication complexity settings of the Yao
and Cleve--Buhrman models.


title: Vortices and Impurities

abstract:
  We describe the BPS dynamics of vortices in the presence of impurities. We
argue that a moduli space of solitons survives the addition of both electric
and magnetic impurities. However, dynamics on the moduli space is altered. In
the case of electric impurities, the metric remains unchanged but the dynamics
is accompanied by a connection term, acting as an effective magnetic field over
the moduli space. We give an expression for this connection and compute the
vortex-impurity bound states in simple cases. In contrast, magnetic impurities
distort the metric on the moduli space. We show that magnetic impurities can be
viewed as vortices associated to a second, frozen, gauge group. We provide a
D-brane description of the dynamics of vortices in product gauge groups and
show how one can take the limit such that a subset of the vortices freeze.


title:
Understanding the Unusual X-Ray Emission Properties of the Massive,
  Close Binary WR 20a: A High Energy Window into the Stellar Wind Initiation
  Region

abstract:
  The problem of explaining the X-ray emission properties of the massive, close
binary WR 20a is discussed. Located near the cluster core of Westerlund 2, WR
20a is composed of two nearly identical Wolf- Rayet stars of 82 and 83 solar
masses orbiting with a period of only 3.7 days. Although Chandra observations
were taken during the secondary optical eclipse, the X-ray light curve shows no
signs of a flux decrement. In fact, WR 20a appears slightly more X-ray luminous
and softer during the optical eclipse, opposite to what has been observed in
other binary systems. To aid in our interpretation of the data, we compare with
the results of hydrodynamical simulations using the adaptive mesh refinement
code Mezcal that includes radiative cooling and a radiative acceleration force
term. It is shown that the X-ray emission can be successfully explained in
models where the wind-wind collision interface in this system occurs while the
outflowing material is still being accelerated. Consequently, WR 20a serves as
a critical test-case for how radiatively-driven stellar winds initiate and
interact. Our models not only procure a robust description of current Chandra
data, which cover the orbital phases between 0.3 to 0.6, but provide detailed
predictions over the entire orbit.


title:
AdS/CFT as classical to quantum correspondence in a Virtual Extra
  Dimension

abstract:
  The correspondence between classical extra dimensional geometry and quantum
behavior, typical of the AdS/CFT, has a heuristic semiclassical interpretation
in terms of undulatory mechanics and relativistic geometrodynamics. We note, in
fact, that the quantum recurrence of ordinary particles enters into the
equations of motions in formal duality with the extra dimensional dynamics of a
Kaluza-Klein theory. The kinematics of the particle in a generic interaction
scheme can be described as modulations of the spacetime recurrences and encoded
in corresponding geometrodynamics. The quantization can be obtained
semiclassically by means of boundary conditions, so that the interference of
the classical paths with different windings numbers associated to the resulting
recurrences turns out to be described by the ordinary Feynman Path Integral.
This description applied to the Quark-Gluon-Plasma freeze-out yields basic
aspects of AdS/QCD phenomenology.


title:
Kinetics of mobile impurities and correlation functions in
  one-dimensional superfluids at finite temperature

abstract:
  We scrutinize the hydrodynamic approach for calculating dynamical
correlations in one-dimensional superfluids near integrability and calculate
the characteristic time scale {\tau} beyond which this approach is valid. For
time scales shorter than {\tau} hydrodynamics fails and we develop an approach
based on kinetics of fermionic quasiparticles described as mobile impurities.
New universal results for the dynamical structure factor relevant to
experiments in ultracold atomic gases are obtained.


title:
Resurrecting My Revolution: Using Social Link Neighborhood in Bringing
  Context to the Disappearing Web

abstract:
  In previous work we reported that resources linked in tweets disappeared at
the rate of 11% in the first year followed by 7.3% each year afterwards. We
also found that in the first year 6.7%, and 14.6% in each subsequent year, of
the resources were archived in public web archives. In this paper we revisit
the same dataset of tweets and find that our prior model still holds and the
calculated error for estimating percentages missing was about 4%, but we found
the rate of archiving produced a higher error of about 11.5%. We also
discovered that resources have disappeared from the archives themselves (7.89%)
as well as reappeared on the live web after being declared missing (6.54%). We
have also tested the availability of the tweets themselves and found that
10.34% have disappeared from the live web. To mitigate the loss of resources on
the live web, we propose the use of a "tweet signature". Using the Topsy API,
we extract the top five most frequent terms from the union of all tweets about
a resource, and use these five terms as a query to Google. We found that using
tweet signatures results in discovering replacement resources with 70+% textual
similarity to the missing resource 41% of the time.


Stable numerical coupling of exterior and interior problems for the wave
  equation


title:
Magnetized Epsilon-Near-Zero (ENZ) Structures: Hall Opacity, Hall
  Transparency, and One-Way Photonic Surface States

abstract:
  We study propagation of transverse-magnetic (TM) electromagnetic waves in the
bulk and at the surface of magnetized epsilon-near-zero (ENZ) medium in a Voigt
configuration. We reveal that in a certain range of material parameters novel
regimes of wave propagation emerge: we show that the transparency of the medium
can be altered with the magnetization leading either to magnetically induced
Hall opacity or Hall transparency of the ENZ. In our theoretical study, we
demonstrate that surface waves at the interface between either a transparent or
an opaque Hall medium and a homogeneous medium may, under certain conditions,
be predominantly one-way. Moreover, we predict that one-way photonic surface
states may exist at the interface of an opaque Hall ENZ and a regular metal,
giving rise to a possibility for backscattering immune wave propagation and
isolation.


title: Single-photon nonlinear optics with graphene plasmons

abstract:
  We show that it is possible to realize significant nonlinear optical
interactions at the few photon level in graphene nanostructures. Our approach
takes advantage of the electric field enhancement associated with the strong
confinement of graphene plasmons and the large intrinsic nonlinearity of
graphene. Such a system could provide a powerful platform for quantum nonlinear
optical control of light. As an example, we consider an integrated optical
device that exploits this large nonlinearity to realize a single photon switch.


title: Functional limit theorems for processes pieced together from excursions

abstract:
  A notion of convergence of excursion measures is introduced. It is proved
that convergence of excursion measures implies convergence in law of the
processes pieced together from excursions. This result is applied to obtain
homogenization theorems of jumping-in extensions for positive self-similar
Markov processes, for Walsh diffusions and for the Brownian motion on the
Sierpi\'nski gasket.


title: Effective actions of non-geometric fivebranes

abstract:
  An interesting consequence of string dualities is that they reveal situations
where the geometry of a string background appears to be globally ill-defined, a
phenomenon usually referred to as non-geometry. On the other hand, string
theory contains extended objects with non-trivial monodromy around them, often
dubbed defect or exotic branes in co-dimension two. We determine and examine
the worldvolume actions and the couplings of certain such branes. In
particular, based on specific chains of T and S-dualities, we derive the DBI
and WZ actions, which describe the dynamics of type IIB fivebranes as well as
their couplings to the appropriate gauge potentials associated to mixed
symmetry tensors. Based on these actions we discuss how these branes act as
sources of non-geometric fluxes. In one case this flux is what is usually
termed Q flux, associated to a T-fold compactification, while in the S-dual
case a type of non-geometry related to the Ramond-Ramond sector is encountered.


title:
Construction of Basis Vectors For Symmetric Irreducible Representations
  of O(5) supset O(3)

abstract:
  A recursive method for construction of symmetric irreducible representations
of O(2l+1) in the O(2l + 1) supset O(3) basis for identical boson systems is
proposed. The formalism is realized based on the group chain U(2l + 1) supset
U(2l- 1) x U(2), of which the symmetric irreducible representations are simply
reducible. The basis vectors of the O(2l+1) supset O(2l-1) x U(1) can easily be
constructed from those of U(2l + 1) supset U(2l-1) x U(2) supset O(2l-1) x U(1)
with no boson pairs, from which one can construct symmetric irreducible
representations of O(2l+1) in the O(2l-1) x U(1) basis when all symmetric
irreducible representations of O(2l-1) are known. As a starting point, basis
vectors of symmetric irreducible representations of O(5) are constructed in the
O1(3) x U(1) basis. Matrix representations of O(5) supset O1(3) x U(1),
together with the elementary Wigner coefficients, are presented. After the
angular momentum projection, a three-term relation in determining the expansion
coefficients of the O(5) supset O(3) basis vectors in terms of those of the
O1(3) x U(1) is derived. The eigenvectors of the projection matrix with zero
eigenvalues constructed according to the three-term relation completely
determine the basis vectors of O(5) supset O(3). Formulae for evaluating the
elementary Wigner coefficients of O(5) supset O(3) are derived explicitly.
Analytical expressions of some elementary Wigner coefficients of O(5) supset
O(3) for the coupling (tau, 0) x (1,0) with resultant angular momentum quantum
number L = 2 tau+ 2 - k for k = 0, 2, 3,...,6 with a multiplicity 2 case for k
= 6 are presented.


title: First-Order Provenance Games

abstract:
  We propose a new model of provenance, based on a game-theoretic approach to
query evaluation. First, we study games G in their own right, and ask how to
explain that a position x in G is won, lost, or drawn. The resulting notion of
game provenance is closely related to winning strategies, and excludes from
provenance all "bad moves", i.e., those which unnecessarily allow the opponent
to improve the outcome of a play. In this way, the value of a position is
determined by its game provenance. We then define provenance games by viewing
the evaluation of a first-order query as a game between two players who argue
whether a tuple is in the query answer. For RA+ queries, we show that game
provenance is equivalent to the most general semiring of provenance polynomials
N[X]. Variants of our game yield other known semirings. However, unlike
semiring provenance, game provenance also provides a "built-in" way to handle
negation and thus to answer why-not questions: In (provenance) games, the
reason why x is not won, is the same as why x is lost or drawn (the latter is
possible for games with draws). Since first-order provenance games are
draw-free, they yield a new provenance model that combines how- and why-not
provenance.


title: Initial state propagators

abstract:
  It is possible to define a general initial state for a quantum field by
introducing a contribution to the action defined at an initial-time boundary.
The propagator for this theory is composed of two parts, one associated with
the free propagation of fields and another produced by the operators of this
initial action. The derivation of this propagator is shown for the case of a
translationally and rotationally invariant initial state. In addition to being
able to treat more general states, these techniques can also be applied to
effective field theories that start from an initial time. The eigenstates of a
theory with interacting heavy and light fields are different from the
eigenstates of the theory in the limit where the interactions vanish.
Therefore, a product of states of the noninteracting heavy and light theories
will usually contain excitations of the heavier state once the interactions are
included. Such excitations appear as nonlocal effects in the effective theory,
which are suppressed by powers of the mass of the heavy field. By appropriately
choosing the initial action, these excitations can be excised from the state
leaving just effects that would be produced by a local action of the lighter
fields.


title:
Monopole operators and Hilbert series of Coulomb branches of 3d N = 4
  gauge theories

abstract:
  This paper addresses a long standing problem - to identify the chiral ring
and moduli space (i.e. as an algebraic variety) on the Coulomb branch of an N =
4 superconformal field theory in 2+1 dimensions. Previous techniques involved a
computation of the metric on the moduli space and/or mirror symmetry. These
methods are limited to sufficiently small moduli spaces, with enough symmetry,
or to Higgs branches of sufficiently small gauge theories. We introduce a
simple formula for the Hilbert series of the Coulomb branch, which applies to
any good or ugly three-dimensional N = 4 gauge theory. The formula counts
monopole operators which are dressed by classical operators, the Casimir
invariants of the residual gauge group that is left unbroken by the magnetic
flux. We apply our formula to several classes of gauge theories. Along the way
we make various tests of mirror symmetry, successfully comparing the Hilbert
series of the Coulomb branch with the Hilbert series of the Higgs branch of the
mirror theory.


title:
XMM-Newton observation of the highly magnetised accreting pulsar Swift
  J045106.8-694803: Evidence of a hot thermal excess

abstract:
  Several persistent, low luminosity (L_X 10^{34} erg s^{-1}), long spin period
(P>100 s) High Mass X-ray Binaries have been reported with blackbody components
with temperatures >1 keV. These hot thermal excesses have correspondingly small
emitting regions (<1 km^2) and are attributed to the neutron star polar caps.
We present a recent XMM-Newton target of opportunity observation of the newest
member of this class, Swift J045106.8-694803. The period was determined to be
168.5+/-0.2 s as of 17 July 2012 (MJD = 56125.0). At $L_X 10^{36} erg s^{-1},
Swift J045106.8-694803 is the brightest member of this new class, as well as
the one with the shortest period. The spectral analysis reveals for the first
time the presence of a blackbody with temperature kT_{BB}=1.8^{+0.2}_{-0.3} keV
and radius R_{BB}=0.5+/-0.2 km. The pulsed fraction decreases with increasing
energy and the ratio between the hard (>2 keV) and soft (<2 keV) light curves
is anticorrelated with the pulse profile. Simulations of the spectrum suggest
that this is caused by the pulsations of the blackbody being pi out of phase
with those of the power law component. Using a simple model for emission from
hot spots on the neutron star surface, we fit the pulse profile of the
blackbody component to obtain an indication of the geometry of the system.


title: Strongly anisotropic Dirac quasiparticles in irradiated graphene

abstract:
  We study quasiparticle dynamics in graphene exposed to a linearly-polarized
electromagnetic wave of very large intensity. Low-energy transport in such
system can be described by an effective time-independent Hamiltonian,
characterized by multiple Dirac points in the first Brillouin zone. Around each
Dirac point the spectrum is anisotropic: the velocity along the polarization of
the radiation significantly exceeds the velocity in the perpendicular
direction. Moreover, in some of the points the transverse velocity oscillates
as a function of the radiation intensity. We find that the conductance of a
graphene p-n junction in the regime of strong irradiation depends on the
polarization as $G(\theta)\propto|\sin\theta|^{3/2}$, where $\theta$ is the
angle between the polarization and the p-n interface, and oscillates as a
function of the radiation intensity.


title: Data-Driven Grasp Synthesis - A Survey

abstract:
  We review the work on data-driven grasp synthesis and the methodologies for
sampling and ranking candidate grasps. We divide the approaches into three
groups based on whether they synthesize grasps for known, familiar or unknown
objects. This structure allows us to identify common object representations and
perceptual processes that facilitate the employed data-driven grasp synthesis
technique. In the case of known objects, we concentrate on the approaches that
are based on object recognition and pose estimation. In the case of familiar
objects, the techniques use some form of a similarity matching to a set of
previously encountered objects. Finally for the approaches dealing with unknown
objects, the core part is the extraction of specific features that are
indicative of good grasps. Our survey provides an overview of the different
methodologies and discusses open problems in the area of robot grasping. We
also draw a parallel to the classical approaches that rely on analytic
formulations.


title: Supercritical problems on manifolds

abstract:
  Let $(M,g)$ be a $m$-dimensional compact Riemannian manifold without
boundary. Assume $\kappa\in C^2(M)$ is such that $-\Delta_g+\kappa$ is
coercive. We prove the existence of a solution to the supercritical problems $$
-\Delta_gu+\kappa u= u^p,\ u>0\quad\hbox{in}\
(M,g)\quad\hbox{and}\quad-\Delta_gu+\kappa u=\lambda e^u\quad\hbox{in}\ (M,g)
$$ which concentrate s along a $(m-1)-$dimensional submanifold of $M$ as
$p\to\infty$ and $\lambda\to0$, respectively, under suitable symmetry
assumptions on the manifold $M$.


title: Complexity in surfaces of densest packings for families of polyhedra

abstract:
  Packings of hard polyhedra have been studied for centuries due to their
mathematical aesthetic and more recently for their applications in fields such
as nanoscience, granular and colloidal matter, and biology. In all these
fields, particle shape is important for structure and properties, especially
upon crowding. Here, we explore packing as a function of shape. By combining
simulations and analytic calculations, we study three 2-parameter families of
hard polyhedra and report an extensive and systematic analysis of the densest
packings of more than 55,000 convex shapes. The three families have the
symmetries of triangle groups (icosahedral, octahedral, tetrahedral) and
interpolate between various symmetric solids (Platonic, Archimedean, Catalan).
We find that optimal (maximum) packing density surfaces that reveal unexpected
richness and complexity, containing as many as 130 different structures within
a single family. Our results demonstrate the utility of thinking of shape not
as a static property of an object in the context of packings, but rather as but
one point in a higher dimensional shape space whose neighbors in that space may
have identical or markedly different packings. Finally, we present and
interpret our packing results in a consistent and generally applicable way by
proposing a method to distinguish regions of packings and classify types of
transitions between them.


title: DNS of the very large anisotropic scales in a turbulent channel

abstract:
  The large structures in the outer layer of turbulent wall flows are of great
physical importance, because they contain a substantial fraction of the
streamwise kinetic energy and of the Reynolds stresses. Nevertheless, the
organization of the outer region of wall turbulence has historically received
less attention than that of the inner region, and as a consequence, it is still
the subject of many open experimental and theoretical questions. In order to
address some of those questions, we have performed direct numerical simulations
of the turbulent incompressible flow in plane channels at Reynolds numbers 185
- 550. This paper presents some of the results of this simulation, focusing on
the statistical description of the size of the large structures of the
streamwise velocity and on its scaling with Reynolds number.


title:
Thermodynamic interpretation of reactive processes in Ni-Al nanolayers
  from atomistic simulations

abstract:
  Metals which can form intermetallic compounds by an exothermic reaction
constitute a class of reactive materials with multiple applications. Ni-Al
laminates of thin alternating layers are being considered as model nanometric
metallic multilayers for studying various reaction processes. However, the
reaction kinetics at short timescales after mixing are not entirely understood.
In this work, we calculate the free energies of Ni-Al alloys as a function of
composition and temperature for different solid phases using thermodynamic
integration based on state-of-the-art interatomic potentials. We use this
information to interpret molecular dynamics (MD) simulations of bilayer systems
at 800 K and zero pressure, both in isothermal and isenthalpic conditions. We
find that a disordered phase always forms upon mixing as a precursor to a more
stable nano crystalline B2 phase. We construe the reactions observed in terms
of thermodynamic trajectories governed by the state variables computed.
Simulated times of up to 30 ns were achieved, which provides a window to
phenomena not previously observed in MD simulations. Our results provide
insight into the early experimental reaction timescales and suggest that the
path (segregated reactants)$\rightarrow$(disordered phase)$\rightarrow$(B2
structure) is always realized irrespective of the imposed boundary conditions.


title: Universal monomer dynamics of a two dimensional semi-flexible chain

abstract:
  We present a unified scaling theory for the dynamics of monomers for dilute
solutions of semiflexible polymers under good solvent conditions in the free
draining limit. Our theory encompasses the well-known regimes of mean square
displacements (MSDs) of stiff chains growing like t^{3/4} with time due to
bending motions, and the Rouse-like regime t^{2 \nu / (1+ 2\nu)} where \nu is
the Flory exponent describing the radius R of a swollen flexible coil. We
identify how the prefactors of these laws scale with the persistence length
l_p, and show that a crossover from stiff to flexible behavior occurs at a MSD
of order l^2_p (at a time proportional to l^3_p). A second crossover (to
diffusive motion) occurs when the MSD is of order R^2. Large scale Molecular
Dynamics simulations of a bead-spring model with a bond bending potential
(allowing to vary l_p from 1 to 200 Lennard-Jones units) provide compelling
evidence for the theory, in D=2 dimensions where \nu=3/4. Our results should be
valuable for understanding the dynamics of DNA (and other semiflexible
biopolymers) adsorbed on substrates.


title: A lower bound for Torelli-K-quasiconformal homogeneity

abstract:
  A closed hyperbolic Riemann surface M is said to be K-quasiconformally
homogeneous if there exists a transitive family F of K-quasiconformal
homeomorphisms. Further, if all [f] in F act trivially on H1(M;Z), we say M is
Torelli-K-quasiconformally homogeneous. We prove the existence of a uniform
lower bound on K for Torelli-K-quasiconformally homogeneous Riemann surfaces.
This is a special case of the open problem of the existence of a lower bound on
K for (in general non-Torelli) K-quasiconformally homogeneous Riemann surfaces.


title:
Multisections of Lefschetz fibrations and topology of symplectic
  4-manifolds

abstract:
  We initiate a study of positive multisections of Lefschetz fibrations via
positive factorizations in framed mapping class groups of surfaces. Using our
methods, one can effectively capture various interesting symplectic surfaces in
symplectic 4-manifolds as multisections, such as Seiberg-Witten basic classes
and exceptional classes, or branched loci of compact Stein surfaces as branched
coverings of the 4-ball. Various problems regarding the topology of symplectic
4-manifolds, such as the smooth classification of symplectic Calabi-Yau
4-manifolds, can be translated to combinatorial problems in this manner. After
producing special monodromy factorizations of Lefschetz pencils on symplectic
Calabi-Yau K3 and Enriques surfaces, and introducing monodromy substitutions
tailored for generating multisections, we obtain several novel applications,
allowing us to construct: new counter-examples to Stipsicz's conjecture on
fiber sum indecomposable Lefschetz fibrations, non-isomorphic Lefschetz pencils
of the same genera on the same new symplectic 4-manifolds, the very first
examples of exotic Lefschetz pencils, and new exotic embeddings of surfaces.


title: Scaling of the energy spectra of wall-bounded turbulence

abstract:
  By using new results from direct simulations of turbulent channels at
moderate friction Reynolds numbers (Retau <= 1900) and in very large numerical
boxes, we examine the corrections to the similarity assumptions in the overlap
and outer regions of wall-bounded turbulence.


title: Statistics of the work distribution for a quenched Fermi gas

abstract:
  The local quench of a Fermi gas, giving rise to the Fermi edge singularity
and the Anderson orthogonality catastrophe, is a rare example of an
analytically tractable out of equilibrium problem in condensed matter. It
describes the universal physics which occurs when a localized scattering
potential is suddenly introduced in a Fermi sea leading to a brutal disturbance
of the quantum state. It has recently been proposed that the effect could be
efficiently simulated in a controlled manner using the tunability of ultra-cold
atoms. In this work, we analyze the quench problem in a gas of trapped
ultra-cold fermions from a thermodynamic perspective using the full statistics
of the so called work distribution. The statistics of work are shown to provide
an accurate insight into the fundamental physics of the process.


title:
Quantum-to-classical transition of primordial cosmological perturbations
  in de Broglie-Bohm quantum theory: the bouncing scenario

abstract:
  In a previous work we have exhibited a clear description of the
quantum-to-classical transition of cosmological quantum fluctuations in the
inflationary scenario using the de Broglie-Bohm quantum theory. These
fluctuations are believed to seed the small inhomogeneities, which are then
responsible for the formation of large scale structures. In this work we show
that using the de Broglie-Bohm theory it is also possible to describe the
quantum-to-classical transition of primordial perturbations which takes place
around a bouncing phase, even if the latter is caused by quantum effects due to
the quantization of the background geometry.


title: Mathieu Moonshine and the Geometry of K3 Surfaces

abstract:
  We compare the moonshine observation of Eguchi, Ooguri and Tachikawa relating
the Mathieu group M_24 and the complex elliptic genus of a K3 surface with the
symmetries of geometric structures on K3 surfaces.
  Two main results are that the complex elliptic genus of a K3 surface is a
virtual module for the Mathieu group M_24 and also for a certain vertex
operator superalgebra V^G where G is the holonomy group.


title:
Mueller Navelet jets at LHC: a clean test of QCD resummation effects at
  high energy?

abstract:
  Mueller Navelet jets were proposed more than 25 years ago as a decisive test
of BFKL dynamics at hadron colliders. We here present a complete
next-to-leading BFKL study of the azimuthal decorrelation of these jets. This
includes both next-to-leading corrections to the Green's function and
next-to-leading corrections to the jet vertices. We compare our results with
recent data taken at the LHC and results obtained in a fixed order
next-to-leading-order (NLO) calculation.


title:
Defects and hyperfine interactions in binary Fe-Al alloys studied by
  positron annihilation and Mossbauer spectroscopies

abstract:
  The defects, the behavior of 3d electrons and the hyperfine interactions in
binary Fe-Al alloys with different Al contents have been studied by the
measurements of positron lifetime spectra, coincidence Doppler broadening
spectra of positron annihilation radiation and Mossbauer spectra. The results
show that on increasing the Al content in Fe-Al alloys, the mean positron
lifetime of the alloys increase, while the mean electron density of the alloys
decrease. The increase of Al content in binary Fe-Al alloys will decrease the
amount of unpaired 3d electrons; as a consequence the probability of positron
annihilation with 3d electrons and the hyperfine field decrease rapidly.
Mossbauer spectra of binary Fe-Al alloys with Al content less than 25at% show
discrete sextets, these alloys give ferromagnetic contribution at room
temperature. The M\"ossbauer spectrum of Fe70Al30 shows a broad singlet. As Al
content higher than 40 at%, the M\"ossbauer spectra of these alloys are
singlet, that is, the alloys are paramagnetic. The behavior of 3d electron and
its effect on the hyperfine field of the binary Fe-Al alloy has been discussed.


title: Artificial magnetic field induced by an evanescent wave

abstract:
  Cold atomic gases are perfect laboratories for realization of quantum
simulators. In order to simulate solid state systems in the presence of
magnetic fields special effort has to be made because atoms are charge neutral.
There are different methods for realization of artificial magnetic fields, that
is the creation of specific conditions so that the motion of neutral particles
mimics the dynamics of charged particles in an effective magnetic field. Here,
we consider adiabatic motion of atoms in the presence of an evanescent wave.
Theoretical description of the adiabatic motion involves artificial vector and
scalar potentials related to the Berry phases. Due to the large gradient of the
evanescent field amplitude, the potentials can be strong enough to induce
measurable effects in cold atomic gases. We show that the resulting artificial
magnetic field is able to induce vortices in a Bose-Einstein condensate trapped
close to a surface of a prism where the evanescent wave is created. We also
analyze motion of an atomic cloud released from a magneto-optical trap that
falls down on the surface of the prism. The artificial magnetic field is able
to reflect falling atoms that can be observed experimentally.


title: A Brief Study of Open Source Graph Databases

abstract:
  With the proliferation of large irregular sparse relational datasets, new
storage and analysis platforms have arisen to fill gaps in performance and
capability left by conventional approaches built on traditional database
technologies and query languages. Many of these platforms apply graph
structures and analysis techniques to enable users to ingest, update, query and
compute on the topological structure of these relationships represented as
set(s) of edges between set(s) of vertices. To store and process Facebook-scale
datasets, they must be able to support data sources with billions of edges,
update rates of millions of updates per second, and complex analysis kernels.
These platforms must provide intuitive interfaces that enable graph experts and
novice programmers to write implementations of common graph algorithms. In this
paper, we explore a variety of graph analysis and storage platforms. We compare
their capabil- ities, interfaces, and performance by implementing and computing
a set of real-world graph algorithms on synthetic graphs with up to 256 million
edges. In the spirit of full disclosure, several authors are affiliated with
the development of STINGER.


title: Greedy Signal Space Methods for incoherence and beyond

abstract:
  Compressive sampling (CoSa) has provided many methods for signal recovery of
signals compressible with respect to an orthonormal basis. However, modern
applications have sparked the emergence of approaches for signals not sparse in
an orthonormal basis but in some arbitrary, perhaps highly overcomplete,
dictionary. Recently, several "signal-space" greedy methods have been proposed
to address signal recovery in this setting. However, such methods inherently
rely on the existence of fast and accurate projections which allow one to
identify the most relevant atoms in a dictionary for any given signal, up to a
very strict accuracy. When the dictionary is highly overcomplete, no such
projections are currently known; the requirements on such projections do not
even hold for incoherent or well-behaved dictionaries. In this work, we provide
an alternate analysis for signal space greedy methods which enforce assumptions
on these projections which hold in several settings including those when the
dictionary is incoherent or structurally coherent. These results align more
closely with traditional results in the standard CoSa literature and improve
upon previous work in the signal space setting.


title: Language change in a multiple group society

abstract:
  The processes leading to change in languages are manifold. In order to reduce
ambiguity in the transmission of information, agreement on a set of conventions
for recurring problems is favored. In addition to that, speakers tend to use
particular linguistic variants associated with the social groups they identify
with. The influence of other groups propagating across the speech community as
new variant forms sustains the competition between linguistic variants. With
the utterance selection model, an evolutionary description of language change,
Baxter et al. [Phys. Rev. E 73, 046118 (2006)] have provided a mathematical
formulation of the interactions inside a group of speakers, exploring the
mechanisms that lead to or inhibit the fixation of linguistic variants. In this
paper, we take the utterance selection model one step further by describing a
speech community consisting of multiple interacting groups. Tuning the
interaction strength between groups allows us to gain deeper understanding
about the way in which linguistic variants propagate and how their distribution
depends on the group partitioning. Both for the group size and the number of
groups we find scaling behaviors with two asymptotic regimes. If groups are
strongly connected, the dynamics is that of the standard utterance selection
model, whereas if their coupling is weak, the magnitude of the latter along
with the system size governs the way consensus is reached. Furthermore, we find
that a high influence of the interlocutor on a speaker's utterances can act as
a counterweight to group segregation.


title:
How HF solutions for the TB interacting electrons in 2D predict SCES
  properties and suggest phenomenology for attaining RTS

abstract:
  Former results for a Tight-Binding (TB) model of CuO planes in La2CuO4 are
reinterpreted here to underline their wider implications. It is noted that
physical systems being appropriately described by the TB model can exhibit the
main strongly correlated electron system (SCES) properties, when they are
solved in the HF approximation, by also allowing crystal symmetry breaking
effects and non-collinear spin orientations of the HF orbitals. It is argued
how a simple 2D square lattice system of Coulomb interacting electrons can
exhibit insulator gaps and pseudogap states, and quantum phase transitions as
illustrated by the mentioned former works. A discussion is also presented here
indicating the possibility of attaining room temperature superconductivity, by
means of a surface coating with water molecules of cleaved planes of graphite,
being orthogonal to its c-axis. The possibility that 2D arrays of quantum dots
can give rise to the same effect is also proposed to consideration. The
analysis also furnishes theoretical insight to solve the Mott-Slater debate, at
least for the La2CuO4 and TMO band structures. The idea is to apply a properly
non-collinear GW scheme to the electronic structure calculation of these
materials. The fact is that the GW approach can be viewed as a HF procedure in
which the screening polarization is also determined. This directly indicates
the possibility of predicting the assumed dielectric constant in the previous
works. Thus, the results seem to identify that the main correlation properties
in these materials are determined by screening. Finally, the conclusions also
seem to be of help for the description of the experimental observations of
metal-insulator transitions and Mott properties in atoms trapped in planar
photonic lattices.


title: Caracterizando la Web Chilena

abstract:
  This article presents a characterization of the web space from Chile in 2007.
The characterization shows distributions of sites and domains, analysis of
document content and server configuration. In addition, the network structure
of the chilean Web is analyzed, determining components based on hyperlink
structure at the document and site levels.
  Original Abstract: En este art\'iculo se muestra una caracterizaci\'on del
espacio web de Chile para el a\~no 2007. Se muestran distribuciones de sitios y
dominios, caracterizaci\'on del contenido en base a tipos de documento, asi
como configuraci\'on de los servidores. Se estudia la estructura de la red
creada mediante hiperv\'inculos en los documentos y c\'omo las diferentes
componentes de esta estructura var\'ian cuando los hiperv\'inculos son
agregados a nivel de sitios.


title: Self-Correcting Quantum Memories Beyond the Percolation Threshold

abstract:
  We analyze several high dimensional generalizations of the toric code at
nonzero temperature. We find that in large enough dimension, there can be a
distinct separation between the critical temperature $T_c$, given by
thermodynamic singularities, and the percolation temperature $T_p$, given by
the percolation of defects. We argue that the regime $T_p<T<T_c$ is a range of
temperatures where a self-correcting quantum memory can operate despite having
percolating defects. We present analytic arguments and numerical evidence in
support of this scenario, including a mean-field treatment and Monte Carlo
simulations. Near $T_c$, simulations observe a large hysteretic behavior, which
may have applications by allowing the self-correcting phase to survive in a
"superheated" regime.


title: Gamma-ray emission from early-type stars interacting with AGN jets

abstract:
  We study the interaction of early-type stars with the jets of active galactic
nuclei. A bow-shock will form as a consequence of the interaction of the jet
with the winds of stars and particles can be accelerated up to relativistic
energies in these shocks. We compute the non-thermal radiation produced by
relativistic electrons from radio to gamma-rays. This radiation may be
significant, and its detection might yield information on the properties of the
stellar population in the galaxy nucleus, as well as on the relativistic jet.
This emission is expected to be relevant for nearby non-blazar sources.


title:
All functions g:N-->N which have a single-fold Diophantine
  representation are dominated by a limit-computable function f:N\{0}-->N which
  is implemented in MuPAD and whose computability is an open problem

abstract:
  Let E_n={x_k=1, x_i+x_j=x_k, x_i \cdot x_j=x_k: i,j,k \in {1,...,n}}. For any
integer n \geq 2214, we define a system T \subseteq E_n which has a unique
integer solution (a_1,...,a_n). We prove that the numbers a_1,...,a_n are
positive and max(a_1,...,a_n)>2^(2^n). For a positive integer n, let f(n)
denote the smallest non-negative integer b such that for each system S
\subseteq E_n with a unique solution in non-negative integers x_1,...,x_n, this
solution belongs to [0,b]^n. We prove that if a function g:N-->N has a
single-fold Diophantine representation, then f dominates g. We present a MuPAD
code which takes as input a positive integer n, performs an infinite loop,
returns a non-negative integer on each iteration, and returns f(n) on each
sufficiently high iteration.


title: Viscoelastic Properties of Vascular Endothelial Cells Exposed to Stretch

abstract:
  In this paper, we study how cytoskeletal remodeling is correlated to changes
in subcellular microrheology. We analyze the changes in the magnitude and
directionality of the shear and elastic moduli of bovine aortic endothelial
cells (BAECs) exposed to cyclical, uniaxial stretch. We find that, when
stretched, BAECs stiffen and align their softest direction of mechanical
polarization perpendicular to stretch. We hypothesize that the response of VECs
to stretch acts to minimize intracellular strain in response to stress.

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


title:
Liquid general anesthetics lower critical temperatures in plasma
  membrane vesicles

abstract:
  A large and diverse array of small hydrophobic molecules induce general
anesthesia. Their efficacy as anesthetics has been shown to correlate both with
their affinity for a hydrophobic environment and with their potency in
inhibiting certain ligand gated ion channels. Here we explore the effects that
n-alcohols and other liquid anesthetics have on the two-dimensional miscibility
critical point observed in cell derived giant plasma membrane vesicles (GPMVs).
We show that anesthetics depress the critical temperature (Tc) of these GPMVs
without strongly altering the ratio of the two liquid phases found below Tc.
The magnitude of this affect is consistent across n-alcohols when their
concentration is rescaled by the median anesthetic concentration (AC50) for
tadpole anesthesia, but not when plotted against the overall concentration in
solution. At AC50 we see a 4{\deg}C downward shift in Tc, much larger than is
typically seen in the main chain transition at these anesthetic concentrations.
GPMV miscibility critical temperatures are also lowered to a similar extent by
propofol, phenylethanol, and isopropanol when added at anesthetic
concentrations, but not by tetradecanol or 2,6 diterbutylphenol, two structural
analogs of general anesthetics that are hydrophobic but have no anesthetic
potency. We propose that liquid general anesthetics provide an experimental
tool for lowering critical temperatures in plasma membranes of intact cells,
which we predict will reduce lipid-mediated heterogeneity in a way that is
complimentary to increasing or decreasing cholesterol. Also, several possible
implications of our results are discussed in the context of current models of
anesthetic action on ligand gated ion channels.

categories: physics.bio-ph cond-mat.soft q-bio.BM q-bio.OT


title: Complete Valuations on Finite Distributive Lattices

abstract:
  We characterize the finite distributive lattices which admit a complete
valuation, that is bijective over a set of consecutive natural numbers, with
the additional conditions of completeness (Definition 2.3). We prove that such
lattices are downset lattices of finite posets of dimension at most two, and
determine a realizer through a recursive relation between weights on the poset
associated to valuation. The relation shows that the weights count chains in
the complementary poset. Conversely, we prove that a valuation defined on a
poset of dimension at most two, through the weight function which counts chains
in the complementary poset, is complete.


title:
Distribution of Traction Forces and Intracellular Markers Associated
  with Shape Changes During Amoeboid Cell Migration

abstract:
  During migration, amoeboid cells perform a cycle of quasi-periodic repetitive
events (motility cycle). the cell length and the strain energy exchanged with
the substrate oscillate in time with an average frequency, f, on top of which
are imposed smaller random fluctuations. the fact that a considerable portion
of the changes in cell shape are due to periodic repetitive events enables the
use of conditional statistics methods to analyze the network of biochemical
processes involved in cell motility. taking advan- tage of this cyclic nature,
we apply Principal Component analysis (PCa) and phase- average statistics to
analyze the dominant modes of shape change and their association to the
activity and localization of molecular motors. We analyze time-lapse measure-
ments of cell shape, traction forces and fluorescence from green fluorescent
protein (GfP) reporters for f-actin in Dictyostelium cells undergoing guided
chemotactic migration. using wild-type cells (wt) as reference, we investigated
the contractile and actin crosslinking functions of myosin II by studying
myosin II heavy chain null mutant cells (mhcA-) and myosin II essential light
chain null cells (mlcE-).


title: CrowdPlanner: A Crowd-Based Route Recommendation System

abstract:
  CrowdPlanner -- a novel crowd-based route recommendation system has been
developed, which requests human workers to evaluate candidates routes
recommended by different sources and methods, and determine the best route
based on the feedbacks of these workers. Our system addresses two critical
issues in its core components: a) task generation component generates a series
of informative and concise questions with optimized ordering for a given
candidate route set so that workers feel comfortable and easy to answer; and b)
worker selection component utilizes a set of selection criteria and an
efficient algorithm to find the most eligible workers to answer the questions
with high accuracy.


title: Outgassing Behavior of C/2012 S1 (ISON) From September 2011 to June 2013

abstract:
  We report photometric observations for comet C/2012 S1 (ISON) obtained during
the time period immediately after discovery (r=6.28 AU) until it moved into
solar conjunction in mid-2013 June using the UH2.2m, and Gemini North 8-m
telescopes on Mauna Kea, the Lowell 1.8m in Flagstaff, the Calar Alto 1.2m
telescope in Spain, the VYSOS-5 telescopes on Mauna Loa Hawaii and data from
the CARA network. Additional pre-discovery data from the Pan STARRS1 survey
extends the light curve back to 2011 September 30 (r=9.4 AU). The images showed
a similar tail morphology due to small micron sized particles throughout 2013.
Observations at sub-mm wavelengths using the JCMT on 15 nights between 2013
March 9 (r=4.52 AU) and June 16 (r=3.35 AU) were used to search for CO and HCN
rotation lines. No gas was detected, with upper limits for CO ranging between
(3.5-4.5)E27 molec/s. Combined with published water production rate estimates
we have generated ice sublimation models consistent with the photometric light
curve. The inbound light curve is likely controlled by sublimation of CO2. At
these distances water is not a strong contributor to the outgassing. We also
infer that there was a long slow outburst of activity beginning in late 2011
peaking in mid-2013 January (r~5 AU) at which point the activity decreased
again through 2013 June. We suggest that this outburst was driven by CO
injecting large water ice grains into the coma. Observations as the comet came
out of solar conjunction seem to confirm our models.


title: Construction of KP solitons from wave patterns

abstract:
  We often observe that waves on the surface of shallow water form complex
web-like patterns. They are examples of nonlinear waves, and these patterns are
generated by nonlinear interactions among several obliquely propagating waves.
In this note, we discuss how to construct an exact soliton solution of the KP
equation from such web-pattern of shallow water wave. This can be regarded as
an "inverse problem" in the sense that by measuring certain metric data of the
solitary waves in the given pattern, it is possible to construct an exact KP
soliton solution which can describe the non-stationary dynamics of the pattern.

categories: nlin.SI math-ph math.MP nlin.PS physics.flu-dyn


title: Energt Efficient MAC Protocols for Wireless Sensor Network: A Survey

abstract:
  Wireless Sensor Network (WSN) is an attractive choice for a variety of
applications as no wired infrastructure is needed. Other wireless networks are
not as energy constrained as WSNs, because they may be plugged into the mains
supply or equipped with batteries that are rechargeable and replaceable. Among
others, one of the main sources of energy depletion in WSN is communications
controlled by the Medium Access Control (MAC) protocols. An extensive survey of
energy efficient MAC protocols is presented in this article. We categorise WSN
MAC protocols in the following categories: controlled access (CA), random
access (RA), slotted protocols (SP) and hybrid protocols (HP). We further
discuss how energy efficient MAC protocols have developed from fixed sleep/wake
cycles through adaptive to dynamic cycles, thus becoming more responsive to
traffic load variations. Finally we present open research questions on MAC
layer design for WSNs in terms of energy efficiency


title: Relaxation pathway confinement in glassy dynamics

abstract:
  We compute for an archetypical glass-forming system the excess of particle
mobility distributions over the corresponding distribution of dynamic
propensity, a quantity that measures the tendency of the particles to be mobile
and reflects the local structural constraints. This enables us to demonstrate
that, on supercooling, the dynamical trajectory in search for a relaxation
event must deal with an increasing confinement of relaxation pathways. This
``entropic funnel'' of relaxation pathways built upon a restricted set of
mobile particles is also made evident from the decay and further collapse of
the associated Shannon entropy.


title:
Equivariant, string and leading order characteristic classes associated
  to fibrations

abstract:
  We construct equivariant, string and leading order characteristic classes and
Chern-Simons classes for certain infinite rank bundles associated to fibrations
occurring in loop spaces, Gromov-Witten theory and gauge theory. Results
include a restatement of the S^1 index theorem using equivariant classes on the
tangent bundle to loop space; the expression of some GW invariants in terms of
string and leading order classes for infinite rank bundles over moduli spaces
of pseudoholomorphic curves for semipositive symplectic manifolds; the
identification of the real cohomology of a loop group with certain string and
leading order classes; the identification of Donaldson's nu-class for
4-manifolds with a leading order class for the fibration of irreducible
connections A over the quotient A/G by the gauge group.


title: A Conflict-Based Path-Generation Heuristic for Evacuation Planning

abstract:
  Evacuation planning and scheduling is a critical aspect of disaster
management and national security applications. This paper proposes a
conflict-based path-generation approach for evacuation planning. Its key idea
is to generate evacuation routes lazily for evacuated areas and to optimize the
evacuation over these routes in a master problem. Each new path is generated to
remedy conflicts in the evacuation and adds new columns and a new row in the
master problem. The algorithm is applied to massive flood scenarios in the
Hawkesbury-Nepean river (West Sydney, Australia) which require evacuating in
the order of 70,000 persons. The proposed approach reduces the number of
variables from 4,500,000 in a Mixed Integer Programming (MIP) formulation to
30,000 in the case study. With this approach, realistic evacuations scenarios
can be solved near-optimally in real time, supporting both evacuation planning
in strategic, tactical, and operational environments.


title: Classical and Quantum Superintegrability with Applications

abstract:
  A superintegrable system is, roughly speaking, a system that allows more
integrals of motion than degrees of freedom. This review is devoted to finite
dimensional classical and quantum superintegrable systems with scalar
potentials and integrals of motion that are polynomials in the momenta. We
present a classification of second-order superintegrable systems in
two-dimensional Riemannian and pseudo-Riemannian spaces. It is based on the
study of the quadratic algebras of the integrals of motion and on the
equivalence of different systems under coupling constant metamorphosis. The
determining equations for the existence of integrals of motion of arbitrary
order in real Euclidean space $E_2$ are presented and partially solved for the
case of third-order integrals. A systematic exposition is given of systems in
two and higher dimensional space that allow integrals of arbitrary order. The
algebras of integrals of motions are not necessarily quadratic but close
polynomially or rationally. The relation between superintegrability and the
classification of orthogonal polynomials is analyzed.


title: Mixtures of Variance-Gamma Distributions

abstract:
  A mixture of variance-gamma distributions is introduced and developed for
model-based clustering and classification. The latest in a growing line of
non-Gaussian mixture approaches to clustering and classification, the proposed
mixture of variance-gamma distributions is a special case of the recently
developed mixture of generalized hyperbolic distributions, and a restriction is
required to ensure identifiability. Our mixture of variance-gamma distributions
is perhaps the most useful such special case and, we will contend, may be more
useful than the mixture of generalized hyperbolic distributions in some cases.
In addition to being an alternative to the mixture of generalized hyperbolic
distributions, our mixture of variance-gamma distributions serves as an
alternative to the ubiquitous mixture of Gaussian distributions, which is a
special case, as well as several non-Gaussian approaches, some of which are
special cases. The mathematical development of our mixture of variance-gamma
distributions model relies on its relationship with the generalized inverse
Gaussian distribution; accordingly, the latter is reviewed before our mixture
of variance-gamma distributions is presented. Parameter estimation carried out
within the expectation-maximization framework.


title: Dynamics of electrochemical flows 1 Motion of electrochemical flows

abstract:
  The motion of the electrolyte, comprising of solute ions and solvent
molecules, is a frequently-occurring natural phenomenon. The motion of the
electrolyte leads to the flows of ions and solvent molecules, known as
electrochemical flows. In this study, we establish a general theory to describe
the motion of the electrochemical flows. Our theory provides a different
approach from others to clarify the details of the transport phenomena for the
electrochemical flows. We derive the governing equations in the electrolyte
fluid from mass, charge, momentum, energy, and concentration conservations. In
addition, we normalize the governing equations to derive the dimensionless
parameters, known as Reynolds, Thompson, Peclet, Prandtl and X numbers. The
physical meaning of these parameter numbers in the electrochemical flow is
discussed in detail. A new number, named X number, appears in the Navier-Stokes
equation symbolizing the balance between the inertia force and the electric
force.


title: Circular Planar Electrical Networks I: The Electrical Poset EP_{n}

abstract:
  Following de Verdi\`{e}re-Gitler-Vertigan and Curtis-Ingerman-Morrow, we
prove a host of new results on circular planar electrical networks. We
introduce a poset EP_{n} of electrical networks with n boundary vertices,
giving two equivalent characterizations, one combinatorial and the other
topological. We then investigate various properties of the EP_{n}, proving that
it is graded by number of edges of critical representatives. Finally, we answer
various enumerative questions related to EP_{n}, adapting methods of Callan and
Stein-Everett.


title: No further gravitational wave modes in $F(T)$ gravity

abstract:
  We explore the possibility of further gravitational wave modes in $F(T)$
gravity, where $T$ is the torsion scalar in teleparallelism. It is explicitly
demonstrated that gravitational wave modes in $F(T)$ gravity are equivalent to
those in General Relativity. This result is achieved by calculating the
Minkowskian limit for a class of analytic function of $F(T)$. This consequence
is also confirmed by the preservative analysis around the flat background in
the weak field limit with the scalar-tensor representation of $F(T)$ gravity.


title:
Dynamics of electrochemical flows 2 Electrochemical flows-through porous
  electrode

abstract:
  The electrolyte (comprising of solute ions and solvents) flow-through the
porous media is frequently encountered in nature or in many engineering
applications, such as the electrochemical systems, manufacturing of composites,
geothermal engineering, soil pollution. In this study, we provide a new general
theory for the electrochemical flows-through porous media. We use static method
and set up two representative elementary volumes (REVs). One is the macroscopic
REV of the mixture of the porous media and the electrolyte, while the other is
the microscopic REV in the electrolyte fluid. The establishment of two REVs
enables us to investigate the details of transports of mass, heat, electric
flied, or momentum in the process of the electrochemical flows-through porous
electrode. In this work, the macroscopic governing equations are derived from
the conservation laws in the macroscopic REV to describe the electrochemical
flows-through porous media. At first, we define the porosity by the volume and
surface and divide the porous media into various categories. Then the
superficial average is transformed into intrinsic averages to derive the
interaction terms between the solid and the fluid, known as terms of
dispersion, tortuosity and interfacial transfer. The macroscopic governing
equations are derived by performing the intrinsic average on the microscopic
governing equations. After done that, the unknown terms related to the
dispersion, tortuosity and interfacial transfer are emerged in the governing
equations.


title:
On the Sojourn Time Distribution in a Finite Population Markovian
  Processor Sharing Queue

abstract:
  We consider a finite population processor-sharing (PS) queue, with Markovian
arrivals and an exponential server. Such a queue can model an interactive
computer system consisting of a bank of terminals in series with a central
processing unit (CPU). For systems with a large population $N$ and a
commensurately rapid service rate, or infrequent arrivals, we obtain various
asymptotic results. We analyze the conditional sojourn time distribution of a
tagged customer, conditioned on the number $n$ of others in the system at the
tagged customer's arrival instant, and also the unconditional distribution. The
asymptotics are obtained by a combination of singular perturbation methods and
spectral methods. We consider several space/time scales and parameter ranges,
which lead to different asymptotic behaviors. We also identify precisely when
the finite population model can be approximated by the standard infinite
population $M/M/1$-PS queue.


title: On Spectral Properties of Finite Population Processor Shared Queues

abstract:
  We consider sojourn or response times in processor-shared queues that have a
finite population of potential users. Computing the response time of a tagged
customer involves solving a finite system of linear ODEs. Writing the system in
matrix form, we study the eigenvectors and eigenvalues in the limit as the size
of the matrix becomes large. This corresponds to finite population models where
the total population is $N\gg 1$. Using asymptotic methods we reduce the
eigenvalue problem to that of a standard differential equation, such as the
Hermite equation. The dominant eigenvalue leads to the tail of a customer's
sojourn time distribution.


title:
Asymptotic Analysis of Spectral Properties of Finite Capacity Processor
  Shared Queues

abstract:
  We consider sojourn (or response) times in processor-shared queues that have
a finite customer capacity. Computing the response time of a tagged customer
involves solving a finite system of linear ODEs. Writing the system in matrix
form, we study the eigenvectors and eigenvalues in the limit as the size of the
matrix becomes large. This corresponds to finite capacity models where the
system can only hold a large number $K$ of customers. Using asymptotic methods
we reduce the eigenvalue problem to that of a standard differential equation,
such as the Airy equation. The dominant eigenvalue leads to the tail of a
customer's sojourn time distribution. Some numerical results are given to
assess the accuracy of the asymptotic results.


title:
Conversion efficiency in the process of co-polarized spontaneous
  four-wave mixing

abstract:
  We study the process of co-polarized spontaneous four-wave mixing in
single-mode optical fibers, with an emphasis on an analysis of the conversion
efficiency. We consider both the monochromatic-pumps and pulsed-pumps regimes,
as well as both the degenerate-pumps and non-degenerate-pumps configurations.
We present analytical expressions for the conversion efficiency, which are
given in terms of double integrals. In the case of pulsed pumps we take these
expressions to closed analytical form with the help of certain approximations.
We present results of numerical simulations, and compare them to values
obtained from our analytical expressions, for the conversion efficiency as a
function of several key experimental parameters.


title:
Some Asymptotic Results for the Transient Distribution of the
  Halfin-Whitt Diffusion Process

abstract:
  We consider the Halfin-Whitt diffusion process $X_d(t)$, which is used, for
example, as an approximation to the $m$-server $M/M/m$ queue. We use recently
obtained integral representations for the transient density $p(x,t)$ of this
diffusion process, and obtain various asymptotic results for the density. The
asymptotic limit assumes that a drift parameter $\beta$ in the model is large,
and the state variable $x$ and the initial condition $x_0$ (with
$X_d(0)=x_0>0$) are also large. We obtain some alternate representations for
the density, which involve sums and/or contour integrals, and expand these
using a combination of the saddle point method, Laplace method and singularity
analysis. The results give some insight into how steady state is achieved, and
how if $x_0>0$ the probability mass migrates from $X_d(t)>0$ to the range
$X_d(t)<0$, which is where it concentrates as $t\to\infty$, in the limit we
consider. We also discuss an alternate approach to the asymptotics, based on
geometrical optics and singular perturbation techniques.


title: Theory of cavity-enhanced spontaneous four wave mixing

abstract:
  In this paper we study the generation of photon pairs through the process of
spontaneous four wave mixing (SFWM) in a $\chi^{(3)}$ cavity. Our key interest
is the generation of photon pairs in a guided-wave configuration - fiber or
waveguide - where at least one of the photons in a given pair is matched in
frequency and bandwidth to a particular atomic transition, as required for the
implementation of photon-atom interfaces. We present expressions, along with
plots, for the two-photon joint intensity both in the spectral and temporal
domains. We also present expressions for the absolute brightness, along with
numerical simulations, and show that the presence of the cavity can result in a
flux enhancement relative to an equivalent source without a cavity.


title: Dynamics of electrochemical flows 3 Closure models

abstract:
  The electrolyte (comprising of solute ions and solvents) flow-through the
porous media is frequently encountered in nature or in many engineering
applications, such as the electrochemical systems, manufacturing of composites,
oil production, geothermal engineering, nuclear thermal disposal, soil
pollution. Our previous work derived the interfacial interaction terms between
the solid and the fluid, which can be used to investigate the details of
transports of mass, heat, electric flied, potential, or momentum in the process
of the electrochemical flows-through porous electrode. In this work, we
establish the closure models for these interfacial interaction terms to close
the governing equations from mathematical algebra. The interfacial interaction
terms regard to the electric field, potential and electric force are firstly
revealed. Our new theory provides a new approach to describe the
electrochemical flows-through porous media.


title: On 1/Z expansion for two-electron systems

abstract:
  The $1/Z$-expansion for the Coulomb system of infinitely massive center of
charge Z and two electrons is discussed. Numerical deficiency in Baker et al,
{\em Phys. Rev. \bf A41}, 1247 (1990) is indicated which continue to raise
doubts in correctness of their calculations of the higher order coefficients in
$1/Z$-expansion expressed in Refs.[4-5]. It is shown that a minor modification
of a few first coefficients found in Ref.[3] allows to calculate the ground
state energies at $Z\ =\ 1, 2,\ldots \ 10$ (as well as at $Z > 10$) with a
portion of 15th decimal digit in comparison with highly accurate calculations
by C. Schwartz and by Nakashima-Nakatsuji. Ground state energies of
two-electron ions $Z=11\ (Na^{9+})$ and $Z=12\ (Mg^{10+})$ are found with 14
decimal digits.


title: Jacobian algebras with periodic module category and exponential growth

abstract:
  The Jacobian algebra associated to a triangulation of a closed surface $S$
with a collection of marked points $M$ is (weakly) symmetric and tame. We show
that for these algebras the Auslander-Reiten translate acts 2-periodical on
objects. Moreover, we show that excluding only the case of a sphere with $4$
(or less) punctures, these algebras are of exponential growth. These four
properties implies that there is a new family of algebras symmetric, tame and
with periodic module category.
  As a consequence of the 2-periodical actions of the Auslander-Reiten
translate on objects, we have that the Auslander-Reiten quiver of the
generalized cluster category $\cC_{(S,M)}$ consists only of stable tubes of
rank $1$ or $2$.


title:
Impact of interparticle dipole-dipole interactions on optical
  nonlinearity of nanocomposites

abstract:
  In this paper, effect of dipole-dipole interactions on nonlinear optical
properties of the system of randomly located semiconductor nanoparticles
embedded in bulk dielectric matrix is investigated. This effect results from
the nonzero variance of the net dipole field in an ensemble. The analytical
expressions describing the contribution of the dipole-dipole coupling to
nonlinear dielectric susceptibility are obtained. The derived relationships are
applicable over the full range of nanoparticle volume fractions. The factors
entering into the contribution and depending on configuration of the dipoles
are calculated for several cases. It is shown that for the different
arrangements of dipole alignments the relative change of this contribution does
not exceed 1/3.


title:
Accelerating moderately stiff chemical kinetics in reactive-flow
  simulations using GPUs

abstract:
  The chemical kinetics ODEs arising from operator-split reactive-flow
simulations were solved on GPUs using explicit integration algorithms. Nonstiff
chemical kinetics of a hydrogen oxidation mechanism (9 species and 38
irreversible reactions) were computed using the explicit fifth-order
Runge-Kutta-Cash-Karp method, and the GPU-accelerated version performed faster
than single- and six-core CPU versions by factors of 126 and 25, respectively,
for 524,288 ODEs. Moderately stiff kinetics, represented with mechanisms for
hydrogen/carbon-monoxide (13 species and 54 irreversible reactions) and methane
(53 species and 634 irreversible reactions) oxidation, were computed using the
stabilized explicit second-order Runge-Kutta-Chebyshev (RKC) algorithm. The
GPU-based RKC implementation demonstrated an increase in performance of nearly
59 and 10 times, for problem sizes consisting of 262,144 ODEs and larger, than
the single- and six-core CPU-based RKC algorithms using the
hydrogen/carbon-monoxide mechanism. With the methane mechanism, RKC-GPU
performed more than 65 and 11 times faster, for problem sizes consisting of
131,072 ODEs and larger, than the single- and six-core RKC-CPU versions, and up
to 57 times faster than the six-core CPU-based implicit VODE algorithm on
65,536 ODEs. In the presence of more severe stiffness, such as ethylene
oxidation (111 species and 1566 irreversible reactions), RKC-GPU performed more
than 17 times faster than RKC-CPU on six cores for 32,768 ODEs and larger, and
at best 4.5 times faster than VODE on six CPU cores for 65,536 ODEs. With a
larger time step size, RKC-GPU performed at best 2.5 times slower than six-core
VODE for 8192 ODEs and larger. Therefore, the need for developing new
strategies for integrating stiff chemistry on GPUs was discussed.


title: Intrinsic-Correlation Quantum Key Generation

abstract:
  A new conceptual key generation scheme is presented by using intrinsic
quantum correlations of single photons between Alice and Bob. The intrinsic
bi-partite correlation functions allow key bit to be generated through high
level communication language i.e. a key bit is directly encoded to shared
correlation functions not to the state and detection of a photon at Bob does
not mean key bit. These make the scheme robust against intercept-resend attack
because Alice and Bob can always check the errors in their measurements and
reveal the presence of Eve in their channel without leaking any key bit
information. The laser source is located in the middle of Alice and Bob,
consists of two modes (x,y), relatively random phase-modulated $(\pm
\frac{\pi}{2})$ weak coherent states combined in a perfect 50/50 beam splitter.
The scheme is strictly relied on the perfect beam splitter and mean photon
number less than 1, where more than one photon in a coherent pulse will
introduce more errors in Bob even without the presence of Eve. From the
percentage of errors in Bob, we can estimate the amount of information will be
leaked to Eve in the photon-number splitting attack. This scheme can preserve
the randomness of phase-randomized light source for doubling the communication
distance as in original Ekert's protocol and providing the raw key generation
rate a factor of 2 higher than weak coherent light protocols.


title:
On Block Security of Regenerating Codes at the MBR Point for Distributed
  Storage Systems

abstract:
  A passive adversary can eavesdrop stored content or downloaded content of
some storage nodes, in order to learn illegally about the file stored across a
distributed storage system (DSS). Previous work in the literature focuses on
code constructions that trade storage capacity for perfect security. In other
words, by decreasing the amount of original data that it can store, the system
can guarantee that the adversary, which eavesdrops up to a certain number of
storage nodes, obtains no information (in Shannon's sense) about the original
data. In this work we introduce the concept of block security for DSS and
investigate minimum bandwidth regenerating (MBR) codes that are block secure
against adversaries of varied eavesdropping strengths. Such MBR codes guarantee
that no information about any group of original data units up to a certain size
is revealed, without sacrificing the storage capacity of the system. The size
of such secure groups varies according to the number of nodes that the
adversary can eavesdrop. We show that code constructions based on Cauchy
matrices provide block security. The opposite conclusion is drawn for codes
based on Vandermonde matrices.


title: Genuine Four Tangle for Four Qubit States

abstract:
  We report a four qubit polynomial invariant that quantifies genuine four-body
correlations. The four qubit invariants are obtained from transformation
properties of three qubit invariants under a local unitary on the fourth qubit.


title: Umklapp Superradiance from a Collisionless Quantum Degenerate Fermi Gas

abstract:
  The quantum dynamics of the electromagnetic light mode of an optical cavity
filled with a coherently driven Fermi gas of ultracold atoms strongly depends
on geometry of the Fermi surface. Superradiant light generation and
self-organization of the atoms can be achieved at low pumping threshold due to
resonant atom-photon Umklapp processes, where the fermions are scattered from
one side of the Fermi surface to the other by exchanging photon momenta. The
cavity spectrum exhibits sidebands, that, despite strong atom-light coupling
and cavity decay, retain narrow linewidth, due to absorptionless transparency
windows outside the atomic particle-hole continuum and the suppression of
inhomogeneous broadening and thermal fluctuations in the collisionless Fermi
gas.


title: The Kac Model Coupled to a Thermostat

abstract:
  In this paper we study a model of randomly colliding particles interacting
with a thermal bath. Collisions between particles are modeled via the Kac
master equation while the thermostat is seen as an infinite gas at thermal
equilibrium at inverse temperature $\beta$. The system admits the canonical
distribution at inverse temperature $\beta$ as the unique equilibrium state. We
prove that any initial distribution approaches the equilibrium distribution
exponentially fast both by computing the gap of the generator of the evolution,
in a proper function space, as well as by proving exponential decay in relative
entropy. We also show that the evolution propagates chaos and that the
one-particle marginal, in the large-system limit, satisfies an effective
Boltzmann-type equation.


title: Abel Summation of Ramanujan-Fourier Series

abstract:
  Using Abel summation the paper proves a weak form of the Wiener-Khinchin
formula for arithmetic functions with point-wise convergent Ramanujan-Fourier
expansions. The main result is that the convolution of most arithmetic
functions possessing an R-F expansion are Abel-summable to a result involving
only the Ramanujan-Fourier coefficients of the R-F expansion(s).


title:
Molecular Beam Epitaxy of Ultra-High Quality AlGaAs/GaAs
  Heterostructures: Enabling Physics in Low-Dimensional Electronic Systems

abstract:
  Among very low disorder systems of condensed matter, the high mobility
two-dimensional electron gas confined in gallium arsenide/aluminum gallium
arsenide heterostructures holds a privileged position as platform for the
discovery of new electronic states driven by strong Coulomb interactions.
Molecular beam epitaxy (MBE), an ultra-high vacuum thin-film deposition
technique, produces the highest quality 2DEGs and has played a central role in
a number of discoveries that have at their root the interplay of reduced
dimensionality, strong electron-electron interactions, and disorder. This
review attempts to describe the latest developments in heterostructure design,
MBE technology, and our evolving understanding of disorder that result in
improved material quality and facilitate discovery of new phenomena at ever
finer energy scales.


title:
Neutron Scattering Evidence for a Periodically-Modulated Superconducting
  Phase in the Underdoped Cuprate La$_{1.905}$Ba$_{0.095}$CuO$_4$

abstract:
  The role of antiferromagnetic spin correlations in high-temperature
superconductors remains a matter of debate. We present inelastic neutron
scattering evidence that gapless spin fluctuations coexist with
superconductivity in La$_{1.905}$Ba$_{0.095}$CuO$_4$. Furthermore, we observe
that both the low-energy magnetic spectral weight and the spin
incommensurability are enhanced by the onset of superconducting correlations.
We propose that the coexistence occurs through intertwining of spatial
modulations of the pair wave function and the antiferromagnetic correlations.
This proposal is also directly relevant to sufficiently underdoped
La$_{2-x}$Sr$_x$CuO$_4$ and YBa$_2$Cu$_3$O$_{6+x}$.


title:
Concepts relating magnetic interactions, intertwined electronic orders
  and strongly correlated superconductivity

abstract:
  Unconventional superconductivity (SC) is said to occur when Cooper pair
formation is dominated by repulsive electron-electron interactions, so that the
symmetry of the pair wavefunction is other than isotropic s-wave. The strong,
on-site, repulsive electron-electron interactions that are the proximate cause
of such superconductivity are more typically drivers of commensurate magnetism.
Indeed, it is the suppression of commensurate antiferromagnetism (AF) that
usually allows this type of unconventional superconductivity to emerge.
Importantly, however, intervening between these AF and SC phases, intertwined
electronic ordered phases of an unexpected nature are frequently discovered.
For this reason, it has been extremely difficult to distinguish the microscopic
essence of the correlated superconductivity from the often spectacular
phenomenology of the intertwined phases. Here we introduce a model conceptual
framework within which to understand the relationship between antiferromagnetic
electron-electron interactions, intertwined ordered phases and correlated
superconductivity. We demonstrate its effectiveness in simultaneously
explaining the consequences of antiferromagnetic interactions for the
copper-based, iron-based and heavy-fermion superconductors, as well as for
their quite distinct intertwined phases.


title:
Stability analysis of positive semi-Markovian jump linear systems with
  state resets

abstract:
  This paper studies the mean stability of positive semi-Markovian jump linear
systems. We show that their mean stability is characterized by the spectral
radius of a matrix that is easy to compute. In deriving the condition we use a
certain discretization of a semi-Markovian jump linear system that preserves
stability. Also we show a characterization for the exponential mean stability
of continuous-time positive Markovian jump linear systems. Numerical examples
are given to illustrate the results.


title:
Asymptotically Optimal Beamforming for Video Streaming in Multi-Antenna
  Interference Networks

abstract:
  In this paper, we consider queue-aware beamforming control for video
streaming applications in multi-antenna interference network. Using heavy
traffic approximation technique, we first derive the diffusion limit for the
discrete time queuing system. Based on the diffusion limit, we formulate an
infinite horizon ergodic control problem to minimize the average power costs of
the base stations subject to the constraints on the playback interruption costs
and buffer overflow costs of the mobile users. To deal with the queue coupling
challenge, we utilize the weak interference coupling property in the network to
derive a closed-form approximate value function of the optimality equation as
well as the associated error bound using perturbation analysis. Based on the
closed-form approximate value function, we propose a low complexity queue-aware
beamforming control algorithm, which is asymptotically optimal for sufficiently
small cross-channel path gain. Finally, the proposed scheme is compared with
various baselines through simulations and it is shown that significant
performance gain can be achieved.


title: Spyhoppers and Stargazers: Can Whales See the Stars?

abstract:
  In Moby Dick, Herman Melville wondered how - or what - whales see with eyes
on opposite sides of their heads. "It is plain that he can never see an object
which is exactly ahead... Is his brain so much more comprehensive, combining
and subtle than man's that he can at the same moment of time attentively
examine two distinct prospects, one on one side of him, and the other in an
exactly opposite direction?" he asked. It's a good question. But if Melville
were alive today he might have pondered something perhaps even more intriguing:
Can whales see the stars?


title: Beyond Planck-Einstein quanta: amplitude driven quantum excitation

abstract:
  Linear-response quantum excitation is proportional to the amplitude of the
field, with the energy of the excitation given by the driving frequency. As the
amplitude is increased, there is a crossover, where the excitation energy is
governed by the amplitude of the driving field, not its frequency. As the
amplitude is increased even further, then complex quantum oscillations develop,
whose origin is related to Wannier-Stark physics, but has no simple
explanation. We illustrate this phenomena with the exact solution of the
simplest model of a charge-density-wave insulator driven by a uniform
time-dependent electric field.


title:
Injection terahertz laser using the resonant inter-layer radiative
  transitions in double-graphene-layer structure

abstract:
  We propose and substantiate the concept of terahertz (THz) laser enabled by
the resonant electron radiative transitions between graphene layers (GLs) in
double-GL structures. We estimate the THz gain for TM-mode exhibiting very low
Drude absorption in GLs and show that the gain can exceed the losses in
metal-metal waveguides at the low end of the THz range. The spectrum of the
emitted photons can be tuned by the applied voltage. A weak temperature
dependence of the THz gain promotes an effective operation at room temperature.


title: Optical diode based on exciton-polaritons

abstract:
  We propose theoretically an optical diode based on exciton-polaritons in
semiconductor microcavities. A flow of polaritons in the bistable regime is
used to send signals through an asymmetric fixed potential that favours the
tunneling of particles in one direction. Through dynamic modelling of the
coherent polariton field, we demonstrate the characteristics of an ideal diode,
namely that the forward signal is fully transmitted while the transmission in
the reverse direction tends to zero, without any additional external control.
Moreover, the system proves to be robust to the presence of disorder, intrinsic
to microcavities, and can function at gigahertz repetition rates.


title:
Lift Enhancement by Dynamically Changing Wingspan in Forward Flapping
  Flight

abstract:
  Stretching and retracting wingspan has been widely observed in the flight of
birds and bats, and its effects on the aerodynamic performance particularly
lift generation are intriguing. The rectangular flat-plate flapping wing with a
sinusoidally stretching and retracting wingspan is proposed as a simple model
of biologically-inspired dynamic morphing wings. Direct numerical simulations
of the low-Reynolds-number flows around the flapping morphing wing in a
parametric space are conducted by using immersed boundary method. It is found
that the instantaneous and time-averaged lift coefficients of the wing can be
significantly enhanced by dynamically changing wingspan in a flapping cycle.
The lift enhancement is caused not only by changing the lifting surface area,
but also manipulating the flow structures that are responsible to the
generation of the vortex lift. The physical mechanisms behind the lift
enhancement are explored by examining the three-dimensional flow structures
around the flapping wing.


title: A connection of the Brascamp-Lieb inequality with Skorokhod embedding

abstract:
  We reveal a connection of the Brascamp-Lieb inequality with Skorokhod
embedding. Error bounds for the inequality in terms of variance are also
provided.


title:
A note on the Fundamental Theorem of Asset Pricing under model
  uncertainty

abstract:
  We show that the results of ArXiv:1305.6008 on the Fundamental Theorem of
Asset Pricing and the super-hedging theorem can be extended to the case in
which the options available for static hedging (\emph{hedging options}) are
quoted with bid-ask spreads. In this set-up, we need to work with the notion of
\emph{robust no-arbitrage} which turns out to be equivalent to no-arbitrage
under the additional assumption that hedging options with non-zero spread are
\emph{non-redundant}. A key result is the closedness of the set of attainable
claims, which requires a new proof in our setting.


title:
Multiway Cut, Pairwise Realizable Distributions, and Descending
  Thresholds

abstract:
  We design new approximation algorithms for the Multiway Cut problem,
improving the previously known factor of 1.32388 [Buchbinder et al., 2013].
  We proceed in three steps. First, we analyze the rounding scheme of
Buchbinder et al., 2013 and design a modification that improves the
approximation to (3+sqrt(5))/4 (approximately 1.309017). We also present a
tight example showing that this is the best approximation one can achieve with
the type of cuts considered by Buchbinder et al., 2013: (1) partitioning by
exponential clocks, and (2) single-coordinate cuts with equal thresholds.
  Then, we prove that this factor can be improved by introducing a new rounding
scheme: (3) single-coordinate cuts with descending thresholds. By combining
these three schemes, we design an algorithm that achieves a factor of (10 + 4
sqrt(3))/13 (approximately 1.30217). This is the best approximation factor that
we are able to verify by hand.
  Finally, we show that by combining these three rounding schemes with the
scheme of independent thresholds from Karger et al., 2004, the approximation
factor can be further improved to 1.2965. This approximation factor has been
verified only by computer.


title:
A variant of the Bombieri-Vinogradov theorem with explicit constants and
  applications

abstract:
  We give an effective version with explicit constants of a mean value theorem
of Vaughan related to the values of \psi(y, \chi), the twisted summatory
function associated to the von Mangoldt function \Lambda and a Dirichlet
character \chi. As a consequence of this result we prove an effective variant
of the Bombieri-Vinogradov theorem with explicit constants. This effective
variant has the potential to provide explicit results in many problems. We give
examples of such results in several number theoretical problems related to
shifted primes.


title:
The Characteristic Mapping Method for the Linear Advection of Arbitrary
  Sets

abstract:
  We present a new numerical method for transporting arbitrary sets in a
velocity field. The method computes a deformation mapping of the domain and
advects particular sets by function composition with the map. This also allows
for the transport of multiple sets at low computational cost. Our strategy is
to separate the computation of short time advection from the storage and
representation of long time deformation maps, employing appropriate grid
resolution for each of these two parts. We show through numerical experiments
that the resulting algorithm is accurate and exhibits significant reductions in
computational time over other methods. Results are presented in two and three
dimensions, and accuracy and efficiency are studied.


title: Non-singular AdS-dS transitions in a landscape scenario

abstract:
  Understanding transitions between different vacua of a multiverse allowing
eternal inflation is an open problem whose resolution is important to gain
insights on the global structure of the spacetime as well as the problem of
measure. In the classical theory, transitions from the anti-deSitter to
deSitter vacua are forbidden due to the big crunch singularity. In this
article, we consider toy landscape potentials: a double well and a triple well
potential allowing anti-deSitter and de-Sitter vacua, in the effective dynamics
of loop quantum cosmology for the $k=-1$ FRW model. We show that due to the
non-perturbative quantum gravity effects as understood in loop quantum
cosmology, non-singular anti-deSitter to de-Sitter transitions are possible. In
the future evolution, an anti-deSitter bubble universe does not encounter a big
crunch singularity but undergoes a big bounce occurring at a scale determined
by the underlying quantum geometry. These non-singular transitions provide a
mechanism through which a probe or a `watcher', used to define a local measure,
can safely evolve through the bounce and geodesics can be smoothly extended
from anti-deSitter to de-Sitter vacua.


title: Two limiting regimes of interacting Bessel processes

abstract:
  We consider the interacting Bessel processes, a family of multiple-particle
systems in one dimension where particles evolve as individual Bessel processes
and repel each other via a log-potential. We consider two limiting regimes for
this family on its two main parameters: the inverse temperature beta and the
Bessel index nu. We obtain the time-scaled steady-state distributions of the
processes for the cases where beta or nu are large but finite. In particular,
for large beta we show that the steady-state distribution of the system
corresponds to the eigenvalue distribution of the beta-Laguerre ensembles of
random matrices. We also estimate the relaxation time to the steady state in
both cases. We find that in the freezing regime beta->infinity, the scaled
final positions of the particles are locked at the square root of the zeroes of
the Laguerre polynomial of parameter nu-1/2 for any initial configuration,
while in the regime nu->infinity, we prove that the scaled final positions of
the particles converge to a single point. In order to obtain our results, we
use the theory of Dunkl operators, in particular the intertwining operator of
type B. We derive a previously unknown expression for this operator and study
its behaviour in both limiting regimes. By using these limiting forms of the
intertwining operator, we derive the steady-state distributions, the
estimations of the relaxation times and the limiting behaviour of the
processes.

categories: math-ph cond-mat.stat-mech math.MP math.PR nlin.SI


title:
Fast computation of computer-generated hologram using Xeon Phi
  coprocessor

abstract:
  We report fast computation of computer-generated holograms (CGHs) using Xeon
Phi coprocessors, which have massively x86-based processors on one chip,
recently released by Intel. CGHs can generate arbitrary light wavefronts, and
therefore, are promising technology for many applications: for example,
three-dimensional displays, diffractive optical elements, and the generation of
arbitrary beams. CGHs incur enormous computational cost. In this paper, we
describe the implementations of several CGH generating algorithms on the Xeon
Phi, and the comparisons in terms of the performance and the ease of
programming between the Xeon Phi, a CPU and graphics processing unit (GPU).