title: The self-assembly of paths and squares at temperature 1

abstract:
  We prove that the number of tile types required to build squares of size n x
n, in Winfree's abstract Tile Assembly Model, when restricted to using only
non-cooperative tile bindings, is at least 2n-1, which is also the best known
upper bound. Non-cooperative self-assembly, also known as temperature 1, is
where tiles bind to each other if they match on one or more sides, whereas in
cooperative binding, some tiles can bind only if they match on multiple sides.
  Our proof introduces a new programming technique for temperature 1, that
disproves the very intuitive and commonly held belief that, in the same model,
assembling paths between two points A and B cannot be done with less tile types
than the Manhattan distance between them. Then, we prove a necessary condition
for these "efficient paths" to be assembled, and show that this necessary
condition cannot hold in completely filled squares.
  This result proves the oldest conjecture in algorithmic self-assembly,
published by Rothemund and Winfree in STOC 2000, in the case where growth
starts from a corner of the square. As a corollary, we establish n as a lower
bound on the tile complexity of the general case. The problem of determining
the minimal number of tile types to self-assemble a shape is known to be
Sigma^p_2-complete.


title: Planck 2013 results. XI. All-sky model of thermal dust emission

abstract:
  This paper presents an all-sky model of dust emission from the Planck 857,
545 and 353 GHz, and IRAS 100 micron data. Using a modified black-body fit to
the data we present all-sky maps of the dust optical depth, temperature, and
spectral index over the 353-3000 GHz range. This model is a tight
representation of the data at 5 arc min. It shows variations of the order of 30
% compared with the widely-used model of Finkbeiner, Davis, and Schlegel. The
Planck data allow us to estimate the dust temperature uniformly over the whole
sky, providing an improved estimate of the dust optical depth compared to
previous all-sky dust model, especially in high-contrast molecular regions. An
increase of the dust opacity at 353 GHz, tau_353/N_H, from the diffuse to the
denser interstellar medium (ISM) is reported. It is associated with a decrease
in the observed dust temperature, T_obs, that could be due at least in part to
the increased dust opacity. We also report an excess of dust emission at HI
column densities lower than 10^20 cm^-2 that could be the signature of dust in
the warm ionized medium. In the diffuse ISM at high Galactic latitude, we
report an anti-correlation between tau_353/N_H and T_obs while the dust
specific luminosity, i.e., the total dust emission integrated over frequency
(the radiance) per hydrogen atom, stays about constant. The implication is that
in the diffuse high-latitude ISM tau_353 is not as reliable a tracer of dust
column density as we conclude it is in molecular clouds where the correlation
of tau_353 with dust extinction estimated using colour excess measurements on
stars is strong. To estimate Galactic E(B-V) in extragalactic fields at high
latitude we develop a new method based on the thermal dust radiance, instead of
the dust optical depth, calibrated to E(B-V) using reddening measurements of
quasars deduced from Sloan Digital Sky Survey data.


title: The Eigenvector Moment Flow and local Quantum Unique Ergodicity

abstract:
  We prove that the distribution of eigenvectors of generalized Wigner matrices
is universal both in the bulk and at the edge. This includes a probabilistic
version of local quantum unique ergodicity and asymptotic normality of the
eigenvector entries. The proof relies on analyzing the eigenvector flow under
the Dyson Brownian motion. The key new ideas are: (1) the introduction of the
eigenvector moment flow, a multi-particle random walk in a random environment,
(2) an effective estimate on the regularity of this flow based on maximum
principle and (3) optimal finite speed of propagation holds for the eigenvector
moment flow with very high probability.


title:
A Comprehensive Analysis of Hadronic b->s Transitions in a Family
  Non-universal Z' Model

abstract:
  Motivated by the latest improved measurements of B-meson decays, we make a
comprehensive analysis of the impact of a family non-universal $Z^{\prime}$
boson on $B_s-\bar{B}_s$ mixing and two-body hadronic B-meson decays, all being
characterized by the quark-level $b\to s$ transition. Explicitly 22 decay modes
and the related 52 observables are considered, and some interesting
correlations between them are also carefully examined. Firstly, the allowed
oases of $b-s-Z^{\prime}$ coupling parameters $|B^{L,R}_{sb}|$ and
$\phi^{L,R}_s$ are extracted from $B_s-\bar{B}_s$ mixing. Then, in the "SM
limit"~({\it i.e.,} no new types of $Z^{\prime}$-induced four-quark operators
arise compared to the SM case), we study the $Z^{\prime}$ effects on $B\to\pi
K$, $\pi K^{\ast}$ and $\rho K$ decays. It is found that a new weak phase
$\phi^{L}_s\sim -90^{\circ}$ is crucial for resolving the observed "$\pi K$ CP
puzzle" and the allowed oases of the other $Z^{\prime}$ coupling parameters are
also strongly restricted. Moreover, the $Z^{\prime}$ effects on $\bar{B}_s\to K
K$, $K K^{\ast}$ and $\pi^0 \phi$ decays, being induced by the same quark-level
$b\to s q\bar{q}~(q=u,d)$ transitions, are also investigated. Especially, it is
found that the decay $\bar{B}_s \to \pi^0 \phi$, once measured, would play a
key role in revealing the observed "$\pi K$ CP puzzle" and probing possible new
physics hints. Finally, to check the non-universality of $Z^{\prime}$ couplings
to light-quark pairs, we have studied the $B\to \phi K$ decays in detail and
found that the left-handed $s-s-Z^{\prime}$ coupling is different from the
$d-d-Z^{\prime}$ one, which is due to the large $A_{CP}^{dir}(B^-\to\phi K^-)$
reported by the BaBar collaboration.


title:
Possible astrometric discovery of a substellar companion to the closest
  binary brown dwarf system WISE J104915.57-531906.1

abstract:
  Using FORS2 on the Very Large Telescope, we have astrometrically monitored
over a period of two months the two components of the brown dwarf system WISE
J104915.57-531906.1, the closest one to the Sun. Our astrometric measurements -
with a relative precision at the milli-arcsecond scale - allow us to detect the
orbital motion and derive more precisely the parallax of the system, leading to
a distance of 2.020+/-0.019 pc. The relative orbital motion of the two objects
is found to be perturbed, which leads us to suspect the presence of a
substellar companion around one of the two components. We also perform VRIz
photometry of both components and compare with models. We confirm the flux
reversal of the T dwarf.


title: On the asymptotic behavior of a Boltzmann-type price formation model

abstract:
  In this paper we study the asymptotic behavior of a Boltzmann type price
formation model, which describes the trading dynamics in a financial market. In
many of these markets trading happens at high frequencies and low transactions
costs. This observation motivates the study of the limit as the number of
transactions $k$ tends to infinity, the transaction cost $a$ to zero and
$ka=const$. Furthermore we illustrate the price dynamics with numerical
simulations.


title:
Nonexistence of quasiconformal maps between certain metric measure
  spaces

abstract:
  We provide new conditions that ensure that two metric measure spaces are not
quasiconformally equivalent. As an application we deduce that there exists no
quasiconformal map between the sub-Riemannian Heisenberg and roto-translation
groups.


title:
Quantum Entanglement of Complex Photon Polarization Patterns in Vector
  Beams

abstract:
  We report the efficient creation and detection of hybrid entanglement between
one photon's polarization and another photon's complex transverse polarization
pattern. The polarization measurement of the first photon triggers a
polarization sensitive imaging of its partner photon, the vector photon, using
a single-photon sensitive camera. Thereby, we reconstruct tomographically the
vector photon's complex polarization patterns dependent on the type of
polarization measurement performed on its partner. We visualize the varying
strengths of polarization entanglement for different transverse regions and
demonstrate a novel feature: each vector photon can be both entangled and not
entangled in polarization with its partner photon. We give an intuitive,
information theoretical explanation for our results.


title: On the invertibility of elementary operators

abstract:
  Let $\mathscr{X}$ be a complex Banach space and $\mathcal{L}(\mathscr{X})$ be
the algebra of all bounded linear operators on $\mathscr{X}$. For a given
elementary operator $\Phi$ of length $2$ on $\mathcal{L}(\mathscr{X})$, we
determine necessary and sufficient conditions for the existence of a solution
of the equation ${\rm X} \Phi=0$ in the algebra of all elementary operators on
$\mathcal{L}(\mathscr{X})$. Our approach allows us to characterize some
invertible elementary operators of length $2$ whose inverses are elementary
operators.


title: Closed BLD-elliptic manifolds have virtually Abelian fundamental groups

abstract:
  We show that a closed, connected, oriented, Riemannian $n$-manifold,
admitting a branched cover of bounded length distortion from $\mathbb R^n$, has
a virtually Abelian fundamental group.


title: On the DoF Region of the K-user MISO Broadcast Channel with Hybrid CSIT

abstract:
  An outer bound for the degrees of freedom (DoF) region of the K-user
multiple-input single-output (MISO) broadcast channel (BC) is developed under
the hybrid channel state information at transmitter (CSIT) model, in which the
transmitter has instantaneous CSIT of channels to a subset of the receivers and
delayed CSIT of channels to the rest of the receivers. For the 3-user MISO BC,
when the transmitter has instantaneous CSIT of the channel to one receiver and
delayed CSIT of channels to the other two, two new communication schemes are
designed, which are able to achieve the DoF tuple of
$\left(1,\frac{1}{3},\frac{1}{3}\right)$, with a sum DoF of $\frac{5}{3}$, that
is greater than the sum DoF achievable only with delayed CSIT. Another
communication scheme showing the benefit of the alternating CSIT model is also
developed, to obtain the DoF tuple of $\left(1,\frac{4}{9},\frac{4}{9}\right)$
for the 3-user MISO BC.


title: Steady-State Flow-Force Compensation in a Hydraulic Spool Valve

abstract:
  A high-speed jet flowing inside of a partially-open hydraulic valve is
accompanied by a reaction force, also referred to as flow force. The nature of
this force has remained a mystery despite an extensive research effort spanning
many decades. The momentum theory on the flow force by Lee and Blackburn (1952)
explains the origin of the flow force and offers a design solution to shape the
valve spool as a turbine bucket. It provides a model to calculate the
compensated flow force as well. This paper shows that the model applies to a
different flow case due to incorrect assumptions made. A corrected equation is
presented based on a detailed analysis of the static-pressure distribution in
the valve cavity as well as on a literature review of pressure loss in
diffusers and nozzles. The new equation is based on the compensation taking
place upstream of the valve orifice, not downstream as assumed by the momentum
theory. The new model can be applied to chamfers or notches on the valve spool
without the need to machine a complete turbine-bucket profile. Keywords: flow
force, flow-force compensation, hydraulic valve design, control volume, fluid
momentum, pressure loss, nozzles, diffusers, CFD.


title: Periodic Structure of the Exponential Pseudorandom Number Generator

abstract:
  We investigate the periodic structure of the exponential pseudorandom number
generator obtained from the map $x\mapsto g^x\pmod p$ that acts on the set
$\{1, \ldots, p-1\}$.


title: Metastability and instability in holographic gauge theories

abstract:
  We review and extend previous results regarding the stability and
thermodynamics of Anti-de Sitter (AdS) spacetime at finite temperature. Using a
combination of analytic and numerical techniques, we compute the energy,
temperature, and entropy of perfect fluid stars in asymptotically AdS
spacetimes. We find that at sufficiently high temperature (in the canonical
ensemble) or energy (in the microcanonical ensemble) these configurations
develop dynamical instabilities, which presumably lead to the formation of a
black hole. We extend our analysis to the case of $AdS \times S$
compactifications stabilized by flux (such as those that arise in supergravity
and string theory), and find that the inclusion of the sphere does not
substantially alter these results. We then map out the phase structure of these
theories in the canonical and microcanonical ensembles, paying attention to
inequivalence of these ensembles for global anti-de Sitter space. With a
certain scaling limit, the critical temperature can be parametrically lower
than the string temperature, so that supergravity is a good description at the
instability point. We comment on the implications of this for the unitarity of
black holes.


title:
Analysis of a Mixed Finite Element Method for a
  Cahn-Hilliard-Darcy-Stokes System

abstract:
  In this paper we devise and analyze a mixed finite element method for a
modified Cahn-Hilliard equation coupled with a non-steady Darcy-Stokes flow
that models phase separation and coupled fluid flow in immiscible binary fluids
and diblock copolymer melts. The time discretization is based on a convex
splitting of the energy of the equation. We prove that our scheme is
unconditionally energy stable with respect to a spatially discrete analogue of
the continuous free energy of the system and unconditionally uniquely solvable.
We prove that the phase variable is bounded in $L^\infty
\left(0,T,L^\infty\right)$ and the chemical potential is bounded in $L^\infty
\left(0,T,L^2\right)$ absolutely unconditionally in two and three dimensions,
for any finite final time $T$. We subsequently prove that these variables
converge with optimal rates in the appropriate energy norms in both two and
three dimensions.


title: Ergodicity of polygonal slap maps

abstract:
  Polygonal slap maps are piecewise affine expanding maps of the interval
obtained by projecting the sides of a polygon along their normals onto the
perimeter of the polygon. These maps arise in the study of polygonal billiards
with non-specular reflections laws. We study the absolutely continuous
invariant probabilities of the slap maps for several polygons, including
regular polygons and triangles. We also present a general method for
constructing polygons with slap maps having more than one ergodic absolutely
continuous invariant probability.


title:
Atom optical shop testing of electrostatic lenses using an atom
  interferometer

abstract:
  We used an atom interferometer for atom optical shop testing of lenses for
atomic de Broglie waves. We measured focal lengths and spherical aberrations of
electrostatic lenses in three independent ways based on contrast data, phase
data, or calculations of de Broglie wavefront curvature. We report focal
lengths of -2.5 km and -21.7 km with 5% uncertainty for different lenses. All
three methods give consistent results. Understanding how lenses magnify and
distort atom interference fringes helps improve atom beam velocity measurements
made with phase choppers [New J. Phys. 13, 115007 (2011)], which in turn will
improve the accuracy of atomic polarizability measurements.


title:
Splitting the source term for the Einstein equation to classical and
  quantum parts

abstract:
  We consider the special and general relativistic extensions of the action
principle behind the Schr\"odinger equation distinguishing classical and
quantum contributions. Postulating a particular quantum correction to the
source term in the classical Einstein equation we identify the conformal
content of the above action and obtain classical gravitation for massive
particles, but with a cosmological term representing off-mass-shell
contribution to the energy-momentum tensor. In this scenario the - on the
Planck scale surprisingly small - cosmological constant stems from quantum
bound states (gravonium) having a Bohr radius $a$ as being \Lambda=3/a^2.


title:
Duality and gauge invariance of noncommutative spacetime Podolsky
  electromagnetic theory

abstract:
  The interest in higher derivatives field theories has its origin mainly in
their influence concerning the renormalization properties of physical models
and to remove ultraviolet divergences. In this letter we have introduced the
noncommutative (NC) version of the Podolsky theory and we investigated the
effect of the noncommutativity over its original gauge invariance property. We
have demonstrated precisely that the noncommutativity spoiled the gauge
invariance of the original action. After that we have used the Noether
dualization technique to obtain a dual and gauge invariant action. More than to
obtain the NC Podolsky theory, we have another motivation in this work, which
is to show that, although the introduction of noncommutativity spoils the gauge
invariance, it is possible to recover this property using a standard
dualization method which did not need any modification due to any NC effect in
the original theory, by the way


title: Topology of Kahler Ricci solitons

abstract:
  We prove that any shrinking Kahler Ricci soliton has only one end, and that
any expanding Kahler Ricci soliton with proper potential has only one end.


title: Implementing generalized measurements with superconducting qubits

abstract:
  We describe a method to perform any generalized purity-preserving measurement
of a qubit with techniques tailored to superconducting systems. First, we
consider two methods for realizing a two-outcome partial projection: using a
thresholded continuous measurement in the circuit QED setup, or using an
indirect ancilla qubit measurement. Second, we decompose an arbitrary
purity-preserving two-outcome measurement into single qubit unitary rotations
and a partial projection. Third, we systematically reduce any multiple-outcome
measurement to a sequence of such two-outcome measurements and unitary
operations. Finally, we consider how to define suitable fidelity measures for
multiple-outcome generalized measurements.


title: The Cauchy problem in hybrid metric-Palatini f(X)-gravity

abstract:
  The well-formulation and the well-posedness of the Cauchy problem is
discussed for {\it hybrid metric-Palatini gravity}, a recently proposed
modified gravitational theory consisting of adding to the Einstein-Hilbert
Lagrangian an $f(R)$ term constructed {\it \`{a} la} Palatini. The theory can
be recast as a scalar-tensor one predicting the existence of a light long-range
scalar field that evades the local Solar System tests and is able to modify
galactic and cosmological dynamics, leading to the late-time cosmic
acceleration. In this work, adopting generalized harmonic coordinates, we show
that the initial value problem can always be {\it well-formulated} and,
furthermore, can be {\it well-posed} depending on the adopted matter sources.


title: Testing Grumiller's modified gravity at galactic scales

abstract:
  Using galactic rotation curves, we test a -quantum motivated- gravity model
that at large distances modifies the Newtonian potential when spherical
symmetry is considered. In this model one adds a Rindler acceleration term to
the rotation curves of disk galaxies. Here we consider a standard and a
power-law generalization of the Rindler modified Newtonian potential that are
hypothesized to play the role of dark matter in galaxies. The new, universal
acceleration has to be -phenomenologically- determined. Our galactic model
includes the mass of the integrated gas and stars for which we consider a free
mass model. We test the model by fitting rotation curves of thirty galaxies
that has been employed to test other alternative gravity models. We find that
the Rindler parameters do not perform a suitable fit to the rotation curves in
comparison to the Burkert dark matter profile, but the models achieve a similar
fit as the NFW's profile does. However, the computed parameters of the Rindler
gravity show some spread, posing the model to be unable to consistently explain
the observed rotation curves.


title:
Cosmology with non-minimal coupled gravity: inflation and perturbation
  analysis

abstract:
  We study a scalar-tensor cosmological model where the Einstein tensor is
non-minimally coupled to the free scalar field dynamics. Using FRW metric, we
investigate the behavior of scale factor for vacuum, matter and dark energy
dominated eras. Especially, we focus on the inflationary behavior at early
universe. Moreover, we study the perturbation analysis of this model in order
to confront the inflation under consideration with the observational results.


title: The Second Law in 4D Einstein-Gauss-Bonnet Gravity

abstract:
  The topological contribution to black hole entropy of a Gauss-Bonnet term in
four dimensions opens up the possibility of a violation of the second law of
thermodynamics in black hole mergers. We show, however, that the second law is
not violated in the regime where Einstein-Gauss-Bonnet holds as an effective
theory and black holes can be treated thermodynamically. For mergers of AdS
black holes, the second law appears to be violated even in Einstein gravity; we
argue, however, that the second law holds when gravitational potential energy
is taken into account.


title:
KPZ relation does not hold for the level lines and the SLE$_\kappa$ flow
  lines of the Gaussian free field

abstract:
  In this paper we mingle the Gaussian free field, the Schramm-Loewner
evolution and the KPZ relation in a natural way, shedding new light on all of
them. Our principal result shows that the level lines and the SLE$_\kappa$ flow
lines of the Gaussian free field do not satisfy the usual KPZ relation. In
order to prove this, we have to make a technical detour: by a careful study of
a certain diffusion process, we provide exact estimates of the exponential
moments of winding of chordal SLE curves conditioned to pass nearby a fixed
point. This extends previous results on winding of SLE curves by Schramm.


title:
Permutation polynomials induced from permutations of subfields, and some
  complete sets of mutually orthogonal latin squares

abstract:
  We present a general technique for obtaining permutation polynomials over a
finite field from permutations of a subfield. By applying this technique to the
simplest classes of permutation polynomials on the subfield, we obtain several
new families of permutation polynomials. Some of these have the additional
property that both f(x) and f(x)+x induce permutations of the field, which has
combinatorial consequences. We use some of our permutation polynomials to
exhibit complete sets of mutually orthogonal latin squares. In addition, we
solve the open problem from a recent paper by Wu and Lin, and we give simpler
proofs of much more general versions of the results in two other recent papers.


title: BCJ duality and double copy in the closed string sector

abstract:
  This paper is focused on the loop-level understanding of the
Bern-Carrasco-Johansson double copy procedure that relates the integrands of
gauge theory and gravity scattering amplitudes. At four points, the first
non-trivial example of that construction is one-loop amplitudes in N=2
super-Yang-Mills theory and the symmetric realization of N=4 matter-coupled
supergravity. Our approach is to use both field and string theory in parallel
to analyze these amplitudes. The closed string provides a natural framework to
analyze the BCJ construction, in which the left- and right-moving sectors
separately create the color and kinematics at the integrand level. At tree
level, in a five-point example, we show that the Mafra-Schlotterer-Stieberger
procedure gives a new direct proof of the color-kinematics double copy. We
outline the extension of that argument to n points. At loop level, the
field-theoretic BCJ construction of N=2 SYM amplitudes introduces new terms,
unexpected from the string theory perspective. We discuss to what extent we can
relate them to the terms coming from the interactions between left- and
right-movers in the string-theoretic gravity construction.


title: Local origin of global contact numbers in frictional ellipsoid packings

abstract:
  In particulate soft matter systems the average number of contacts $Z$ of a
particle is an important predictor of the mechanical properties of the system.
Using X-ray tomography, we analyze packings of frictional, oblate ellipsoids of
various aspect ratios $\alpha$, prepared at different global volume fractions
$\phi_g$. We find that $Z$ is a monotonously increasing function of $\phi_g$
for all $\alpha$. We demonstrate that this functional dependence can be
explained by a local analysis where each particle is described by its local
volume fraction $\phi_l$ computed from a Voronoi tessellation. $Z$ can be
expressed as an integral over all values of $\phi_l$: $Z(\phi_g, \alpha, X) =
\int Z_l (\phi_l, \alpha, X) \; P(\phi_l | \phi_g) \; d\phi_l$. The local
contact number function $ Z_l (\phi_l, \alpha, X)$ describes the relevant
physics in term of locally defined variables only, including possible higher
order terms $X$. The conditional probability $P(\phi_l | \phi_g)$ to find a
specific value of $\phi_l$ given a global packing fraction $\phi_g$ is found to
be independent of $\alpha$ and $X$. Our results demonstrate that for frictional
particles a local approach is not only a theoretical requirement but also
feasible.


title:
Remote Life Detection Criteria, Habitable Zone Boundaries, and the
  Frequency of Earthlike Planets around M and Late-K Stars

abstract:
  The habitable zone (HZ) around a star is typically defined as the region
where a rocky planet can maintain liquid water on its surface. That definition
is appropriate, because this allows for the possibility that carbon-based,
photosynthetic life exists on the planet in sufficient abundance to modify the
planet's atmosphere in a way that might be remotely detected. Exactly what
conditions are needed, however, to maintain liquid water remains a topic for
debate. Historically, modelers have restricted themselves to water-rich planets
with CO2 and H2O as the only important greenhouse gases. More recently, some
researchers have suggested broadening the definition to include arid, 'Dune'
planets on the inner edge and planets with captured H2 atmospheres on the outer
edge, thereby greatly increasing the HZ width. Such planets could exist, but we
demonstrate that an inner edge limit of 0.59 AU or less is physically
unrealistic. We further argue that conservative HZ definitions should be used
for designing future space-based telescopes, but that optimistic definitions
may be useful in interpreting the data from such missions. In terms of
effective solar flux, Seff, the recently recalculated HZ boundaries are: recent
Venus-1.78, runaway greenhouse-1.04, moist greenhouse-1.01, maximum
greenhouse-0.35, early Mars-0.32. Based on a combination of different HZ
definitions, the frequency of potentially Earth-like planets around late-K and
M stars observed by Kepler is in the range of 0.4-0.5.


title: Quantifying quantumness via commutators: an application to quantum walk

abstract:
  The question of witnessing or quantifying nonclassicality of quantum systems
has been addressed in various ways. For a given system or theory, we propose
identifying it with the incompatibility of admissible states. We quantify the
nonclassicality of quantum systems using the Hilbert-Schmidt norm of the
commutator of two states. As a particular application of this measure, we study
the classicalization of a discrete-time quantum walk with a noisy coin.


title:
Cohomological dimension filtration and annihilators of top local
  cohomology modules

abstract:
  Let $\frak a$ denote an ideal in a commutative Noetherian ring $R$ and $M$ a
finitely generated $R$-module. In this paper, we introduce the concept of the
cohomological dimension filtration $\mathscr{M} =\{M_i\}_{i=0}^c$, where $
c={\rm cd} ({\frak a},M)$ and $M_i$ denotes the largest submodule of $M$ such
that ${\rm cd} ({\frak a}, M_i)\leq i.$ Some properties of this filtration are
investigated. In particular, in the case that $(R, \frak m)$ is local and $c=
\dim M$, we are able to determine the annihilator of the top local cohomology
module $H_{\frak a}^c(M)$. In fact, it is shown that ${\rm Ann}_R(H_{\frak
a}^c(M))= {\rm Ann}_R(M/M_{c-1}).$ As a consequence, it follows that there
exists an ideal $\frak b$ of $R$ such that ${\rm Ann}_R(H_{\frak
a}^{c}(M))={\rm Ann}_R(M/H_{\frak b}^{0}(M))$.


title:
Properties of sodium-driven bacterial flagellar motor: A two-state model
  approach

abstract:
  Bacterial flagellar motor (BFM) is one of the ion-driven molecular machines,
which drives the rotation of flagellar filaments and enable bacteria to swim in
viscous solutions. Understanding its mechanism is one challenge in biophysics.
Based on previous models and inspired by the idea used in description of motor
proteins, in this study one two-state model is provided. Meanwhile, according
to corresponding experimental data, mathematical relationship between BFM
membrane voltage and pH value of the environment, and relationship between
internal and external sodium concentrations are given. Therefore, with model
parameter values obtained by fitting theoretical results of torque-speed
relation to recent experimental data, many biophysical properties of bacterial
flagellar motor can be obtained for any pH values and any external sodium
concentrations. Including the rotation speed, stall torque (i.e. the torque
generated by BFM), rotation dispersion, and rotation randomness. In this study,
the single-stator BFM will be firstly analyzed, and then properties of
multiple-stator BFM are addressed briefly.


title:
Optimization of Radiation Therapy Fractionation Schedules in the
  Presence of Tumor Repopulation

abstract:
  We analyze the effect of tumor repopulation on optimal dose delivery in
radiation therapy. We are primarily motivated by accelerated tumor repopulation
towards the end of radiation treatment, which is believed to play a role in
treatment failure for some tumor sites. A dynamic programming framework is
developed to determine an optimal fractionation scheme based on a model of cell
kill due to radiation and tumor growth in between treatment days. We find that
faster tumor growth suggests shorter overall treatment duration. In addition,
the presence of accelerated repopulation suggests larger dose fractions later
in the treatment to compensate for the increased tumor proliferation. We prove
that the optimal dose fractions are increasing over time. Numerical simulations
indicate potential for improvement in treatment effectiveness.


title: Direct Measurement of Random Fields in the $LiHo_xY_{1-x}F_4$ Crystal

abstract:
  The random field Ising model (RFIM) is central to the study of disordered
systems. Yet, for a long time it eluded realization in ferromagnetic systems
because of the difficulty to produce locally random magnetic fields. Recently
it was shown that in anisotropic dipolar magnetic insulators, the archetypal of
which is the $LiHo_xY_{1-x}F_4$ system, the RFIM can be realized in both
ferromagnetic and spin glass phases. The interplay between an applied
transverse field and the offdiagonal terms of the dipolar interaction produce
effective longitudinal fields, which are random in sign and magnitude as a
result of spatial dilution. In this paper we use exact numerical
diagonalization of the full Hamiltonian of Ho pairs in $LiHo_xY_{1-x}F_4$ to
calculate the effective longitudinal field beyond the perturbative regime. In
particular, we find that nearby spins can experience an effective field larger
than the intrinsic dipolar broadening (of quantum states in zero field) which
can therefore be evidenced in experiments. We then calculate the magnetization
and susceptibility under several experimental protocols, and show how these
protocols can produce direct measurement of the effective longitudinal field.


title:
Cogenesis in a universe with vanishing $B-L$ within a gauged $U(1)_x$
  extension

abstract:
  We consider a gauged $U(1)_x$ extension of the standard model and of the
minimal supersymmetric standard model where the dark matter fields are charged
under $U(1)_x$ and carry lepton number while the standard model fields and
fields of the minimal supersymmetric standard model are neutral under $U(1)_x$.
We consider leptogenesis in this class of models with all fundamental
interactions having no violation of lepton number, and the total $B-L$ in the
universe vanishes. Such leptogenesis leads to equal and opposite lepton numbers
in the visible sector and in the dark sector, and thus also produces asymmetric
dark matter. Part of the lepton numbers generated in the leptonic sector
subsequently transfer to the baryonic sector via sphaleron interactions. The
stability of the dark particles is protected by the $U(1)_x$ gauge symmetry. A
kinetic mixing between the $U(1)_x$ and the $U(1)_Y$ gauge bosons allows for
dissipation of the symmetric component of dark matter. The case when $U(1)_x$
is $U(1)_{B-L}$ is also discussed for the supersymmetric case. This case is
particularly interesting in that we have a gauged $U(1)_{B-L}$ which ensures
the conservation of $B-L$ with an initial condition of a vanishing $B-L$ in the
universe. Phenomenological implications of the proposed extensions are
discussed, which include implications for electroweak physics, neutrino masses
and mixings, and lepton flavor changing processes such as $\ell_i \to \ell_j
\gamma$. We also briefly discuss the direct detection of the dark matter in the
model.


title:
Afterglow rebrightenings as a signature of a long-lasting central engine
  activity? The emblematic case of GRB 100814A

abstract:
  In the past few years the number of well-sampled optical to NIR light curves
of long Gamma-Ray Bursts (GRBs) has greatly increased particularly due to
simultaneous multi-band imagers such as GROND. Combining these densely sampled
ground-based data sets with the Swift UVOT and XRT space observations unveils a
much more complex afterglow evolution than what was predicted by the most
commonly invoked theoretical models. GRB 100814A represents a remarkable
example of these interesting well-sampled events, showing a prominent late-time
rebrightening in the optical to NIR bands and a complex spectral evolution.
This represents a unique laboratory to test the different afterglow emission
models. Here we study the nature of the complex afterglow emission of GRB
100814A in the framework of different theoretical models. Moreover, we compare
the late-time chromatic rebrightening with those observed in other well-sampled
long GRBs. We analysed the optical and NIR observations obtained with the
seven-channel Gamma-Ray burst Optical and Near-infrared Detector at the 2.2 m
MPG/ESO telescope together with the X-ray and UV data detected by the
instruments onboard the Swift observatory. The broad-band afterglow evolution,
achieved by constructing multi-instrument light curves and spectral energy
distributions, will be discussed in the framework of different theoretical
models. We find that the standard models that describe the broad-band afterglow
emission within the external shock scenario fail to describe the complex
evolution of GRB 100814A, and therefore more complex scenarios must be invoked.
[abridged]


title: Direct and indirect detection of dissipative dark matter

abstract:
  We study the constraints from direct detection and solar capture on dark
matter scenarios with a subdominant dissipative component. This dissipative
dark matter component in general has both a symmetric and asymmetric relic
abundance. Dissipative dynamics allow this subdominant dark matter component to
cool, resulting in its partial or total collapse into a smaller volume inside
the halo (e.g., a dark disk) as well as a reduced thermal velocity dispersion
compared to that of normal cold dark matter. We first show that these features
considerably relax the limits from direct detection experiments on the
couplings between standard model (SM) particles and dissipative dark matter. On
the other hand, indirect detection of the annihilation of the symmetric
dissipative dark matter component inside the Sun sets stringent and robust
constraints on the properties of the dissipative dark matter. In particular,
IceCube observations force dissipative dark matter particles with mass above 50
GeV to either have a small coupling to the SM or a low local density in the
solar system, or to have a nearly asymmetric relic abundance. Possible
helioseismology signals associated with purely asymmetric dissipative dark
matter are discussed, with no present constraints.


title:
The Mystery of the $\sigma$-Bump -- A new Signature for Major Mergers in
  Early-type Galaxies?

abstract:
  The stellar velocity dispersion as a function of the galactocentric radius of
an early-type galaxy can generally be well approximated by a power law $\sigma
\propto r^{\beta}$. However, some observed dispersion profiles show a deviation
from this fit at intermediate radii, usually between one and three
$R_{\mathrm{eff}}$, where the velocity dispersion remains constant with radius,
showing a bump-like behavior, which we term the "$\sigma$-"bump. To understand
the origin of this $\sigma$-bump, we study a set of simulated early-type
galaxies formed in major mergers. We find the $\sigma$-bump in all of our
simulated early-type galaxies, with the size and position of the bump slightly
varying from galaxy to galaxy, leading to the assumption that the bump is a
characteristic of the major merger formation scenario. The feature can be seen
both in the intrinsic and projected stellar velocity dispersions. In contrast
to shells that form during the merger event but evolve with time and finally
disappear, the $\sigma$-bump stays nearly constant with radius and is a
permanent feature that is preserved until the end of the simulation. The
$\sigma$-bump is not seen in the dark matter and gas components and we
therefore conclude that it is a purely stellar feature of merger remnants.


title: Magnetically Aligned HI Fibers and the Rolling Hough Transform

abstract:
  We present observations of a new group of structures in the diffuse Galactic
ISM: slender, linear HI features we dub "fibers" that extend for many degrees
at high Galactic latitude. To characterize and measure the extent and strength
of these fibers, we present the Rolling Hough Transform (RHT), a new machine
vision method for parameterizing the coherent linearity of structures in the
image plane. With this powerful new tool we show the fibers are oriented along
the interstellar magnetic field as probed by starlight polarization. We find
that these low column density (N(HI) ~ 5 x 10^18 cm^-2) fiber features are most
likely a component of the local cavity wall, about 100 pc away. The HI data we
use to demonstrate this alignment at high latitude are from the Galactic
Arecibo L-Band Feed Array HI (GALFA-HI) Survey and the Parkes Galactic All Sky
Survey (GASS). We find better alignment in the higher resolution GALFA-HI data,
where the fibers are more visually evident. This trend continues in our
investigation of magnetically aligned linear features in the Riegel-Crutcher HI
cold cloud, detected in the Southern Galactic Plane Survey (SGPS). We propose
an application of the RHT for estimating the field strength in such a cloud,
based on the Chandrasekhar-Fermi method. We conclude that data-driven,
quantitative studies of ISM morphology can be very powerful predictors of
underlying physical quantities.


title: Discovery of a new black hole transient within 100" (400 pc) of M31*

abstract:
  We identified a new X-ray transient CXOM31 004252.457+411631.17 (T13) in M31
during a 2013 June Chandra observation. This system is particularly exciting
because it is located within 100" of M31*; it is thought that this region of
the bulge is sufficiently dense to form X-ray binaries dynamicaly, but only
systems with black hole accretors and/or short periods are expected to survive.
A follow-up XMM-Newton observation yielded a soft spectrum, well described by a
0.39+/-0.02 keV disk blackbody; applying this model to the Chandra observation
yielded an observed 0.3--10 keV luminosity peak of 6.2+/-0.6 E+37 erg/s (4.7
E+36 erg/s in the 2.0--10 keV band). Observing with HST/ACS did not reveal an
optical counterpart, but allowed us to place an upper limit of B >26.9,
corresponding to an absolute V band magnitude >2.0. From the 2--10 keV
luminosity and absolute V magnitude, we estimate an orbital period $<$5 h from
an empirical relation. Fitting a disk blackbody + blackbody model allows us to
reject a neutron star accretor at a 14 sigma level.


title:
More than just halo mass: Modelling how the red galaxy fraction depends
  on multiscale density in a HOD framework

abstract:
  The fraction of galaxies with red colours depends sensitively on environment,
and on the way in which environment is measured. To distinguish competing
theories for the quenching of star formation, a robust and complete description
of environment is required, to be applied to a large sample of galaxies. The
environment of galaxies can be described using the density field of neighbours
on multiple scales - the multiscale density field. We are using the Millennium
simulation and a simple HOD prescription which describes the multiscale density
field of Sloan Digital Sky Survey DR7 galaxies to investigate the dependence of
the fraction of red galaxies on the environment. Using a volume limited sample
where we have sufficient galaxies in narrow density bins, we have more dynamic
range in halo mass and density for satellite galaxies than for central
galaxies. Therefore we model the red fraction of central galaxies as a constant
while we use a functional form to describe the red fraction of satellites as a
function of halo mass which allows us to distinguish a sharp from a gradual
transition. While it is clear that the data can only be explained by a gradual
transition, an analysis of the multiscale density field on different scales
suggests that colour segregation within the haloes is needed to explain the
results. We also rule out a sharp transition for central galaxies, within the
halo mass range sampled.


title: Doubling down on naturalness with a supersymmetric twin Higgs

abstract:
  We show that naturalness of the weak scale can be comfortably reconciled with
both LHC null results and observed Higgs properties provided the double
protection of supersymmetry and the twin Higgs mechanism. This double
protection radically alters conventional signs of naturalness at the LHC while
respecting gauge coupling unification and precision electroweak limits. We find
the measured Higgs mass, couplings, and percent-level naturalness of the weak
scale are compatible with stops at ~3.5 TeV and higgsinos at ~1 TeV. The
primary signs of naturalness in this scenario include modifications of Higgs
couplings, a modest invisible Higgs width, resonant Higgs pair production, and
an invisibly-decaying heavy Higgs.


title:
Distinguishing models of reionization using future radio observations of
  21-cm 1-point statistics

abstract:
  We explore the impact of reionization topology on 21-cm statistics. Four
reionization models are presented which emulate large ionized bubbles around
over-dense regions (21CMFAST/ global-inside- out), small ionized bubbles in
over-dense regions (local-inside-out), large ionized bubbles around under-dense
regions (global-outside-in) and small ionized bubbles around under-dense
regions (local-outside-in). We show that first-generation instruments might
struggle to distinguish global models using the shape of the power spectrum
alone. All instruments considered are capable of breaking this degeneracy with
the variance, which is higher in outside-in models. Global models can also be
distinguished at small scales from a boost in the power spectrum from a
positive correlation between the density and neutral-fraction fields in
outside-in models. Negative skewness is found to be unique to inside-out models
and we find that pre-SKA instruments could detect this feature in maps smoothed
to reduce noise errors. The early, mid and late phases of reionization imprint
signatures in the brightness-temperature moments, we examine their model
dependence and find pre-SKA instruments capable of exploiting these timing
constraints in smoothed maps. The dimensional skewness is introduced and is
shown to have stronger signatures of the early and mid-phase timing if the
inside-out scenario is correct.


title: Charge order driven by Fermi-arc instability in Bi2201

abstract:
  The understanding of the origin of superconductivity in cuprates has been
hindered by the apparent diversity of intertwining electronic orders in these
materials. We combined resonant x-ray scattering (REXS), scanning-tunneling
microscopy (STM), and angle-resolved photoemission spectroscopy (ARPES) to
observe a charge order that appears consistently in surface and bulk, and in
momentum and real space within one cuprate family, Bi2201. The observed wave
vectors rule out simple antinodal nesting in the single-particle limit but
match well with a phenomenological model of a many-body instability of the
Fermi arcs. Combined with earlier observations of electronic order in other
cuprate families, these findings suggest the existence of a generic
charge-ordered state in underdoped cuprates and uncover its intimate connection
to the pseudogap regime.


title: Do the spectral energy distributions of type 1 AGN show diversity?

abstract:
  We create broadband SEDs of 761 type 1 AGN. The Scott et al. sample, created
by a cross-correlation of the optical SDSS DR5 quasar catalogue and the 2XMMi
catalogue of serendipitous X-ray sources, is further matched with the FIRST
catalogue of radio sources, the WISE MIR all-sky data release, the 2MASS NIR
point source catalogue, the UKIDSS DR9 Large Area Survey and the GALEX all-sky
and medium UV imaging surveys. This allows broadband SEDs covering
log(nu)~9.2-18.1 to be created. We investigate variations in the SED shape by
binning a subsample of 237 AGN with the best quality SEDs according to their
X-ray spectral parameters, their AGN sub-type and their luminosity, black hole
mass and Eddington ratio. The AGN sub-populations show some significant
differences in their SEDs; X-ray absorbed AGN show a deficit of emission at
X-ray/UV frequencies and an excess in the MIR consistent with absorption and
re-emission, radio-loud AGN show increased radio and X-ray emission, consistent
with the presence of a jet component in addition to the emission seen from
radio-quiet AGN and the SEDs of NLS1s only differ from other type 1s in the
X-ray regime, suggesting any physical differences are limited to their X-ray
emitting region. Binning the AGN according to underlying physical parameters
reveals more subtle differences in the SEDs. The X-ray spectral slope does not
appear to have any influence or dependence on the multiwavelength emission in
the rest of the SED. The contribution of X-rays to Lbol is lower in higher
luminosity sources, and relatively more emission in the optical/UV is seen in
AGN with higher Lx. Variations in the relative flux and peak frequency of the
BBB are observed and may suggest higher inner disc temperatures with increasing
accretion rates. Overall, we find that the diversity in the SED shapes is
relatively small, and we find no apparent single driver for the variations.


title:
The whole is greater than the sum of the parts: on the possibility of
  purely statistical interpretations of quantum theory

abstract:
  The Pusey-Barrett-Rudolph theorem (PBR) claims to rule out the possibility of
a purely statistical interpretation of the quantum state under an assumption of
how to represent independent operations in any hidden variable model. We show
that PBR's assumption of independence encodes an assumption of local causality,
which is already known to conflict with the predictions of quantum theory via
Bell-type inequalities. We devise a weaker formulation of independence within a
general hidden variable model that is empirically indistinguishable from the
PBR assumption in situations where certain hidden variables are inaccessible.
Under this weaker principle we are able to construct an explicit hidden
variable model that is purely statistical and also reproduces the quantum
predictions. Our results suggest that the assumption of a purely statistical
interpretation is actually an innocent bystander in the PBR argument, rather
than the driving force behind their contradiction.


title:
Star formation activity and gas stripping in the Cluster Projected
  Phase-Space (CPPS)

abstract:
  This work is focused on the study of the distribution in the CPPS of passive
and star-forming galaxy populations and also, the intense and quiescent
star-forming populations for a set of 9 nearby z<0.05 galaxy clusters.
Furthermore, we compare the CPPS distribution of the passive galaxy population
with the accreted halo population of a set of 28 simulated clusters and the
star-forming population with the non-accreted population. We consider various
cluster accretion epochs and accretion radii where it is assumed that star
formation in galaxies becomes quenched, in order to segregate the accreted
population from the non-accreted population. Just applying this segregation in
simulations, we get a qualitative agreement between the CPPS distributions of
the passive and the accreted populations and also between the star-forming and
the non-accreted populations. The uncertainty in cluster centering strongly
affects the pronounced cuspy profiles of the projected density and also, it can
explain the main difference (i.e. inner slope) between the CPPS distribution of
passive and accreted populations. The CPPS density of star-forming galaxies and
the intensity of ram-pressure stripping present an opposite trend throughout
the CPPS. This implies that ram-pressure stripping significantly contributes to
modulate the observed CPPS distribution of star-forming galaxies inside and
around cluster virial regions. The significant fraction of star-forming
galaxies at the projected center of clusters are mainly those galaxies with low
l-o-s velocities and they can be mainly identified as those galaxies with a
remaining star formation activity (quiescent star-forming galaxies) inside the
physical virial region or, in a lower degree, as galaxy interlopers i.e.
outside the physical virial region.(abridged)


title:
Ubiquitous Interplay between Charge Ordering and High-Temperature
  Superconductivity in Cuprates

abstract:
  Besides superconductivity, copper-oxide high temperature superconductors are
susceptible to other types of ordering. We use scanning tunneling microscopy
and resonant elastic x-ray scattering measurements to establish the formation
of charge ordering in the high-temperature superconductor Bi2Sr2CaCu2O8+x.
Depending on the hole concentration, the charge ordering in this system occurs
with the same period as those found in Y-based or La-based cuprates, and
displays the analogous competition with superconductivity. These results
indicate the similarity of charge organization competing with superconductivity
across different families of cuprates. We observe this charge ordering to leave
a distinct electron-hole asymmetric signature (and a broad resonance centered
at +20 meV) in spectroscopic measurements, thereby indicating that it is likely
related to the organization of holes in a doped Mott insulator.


title: Probing Compressed Top Squarks at the LHC at 14 TeV

abstract:
  A feasibility study is presented for the search of the lightest top squark in
a compressed scenario, where its mass is approximately equal to the sum of the
masses of the top quark and the lightest neutralino. The study is performed in
the final state of two b-jets, one lepton, large missing energy, and two
high-$E_{\rm T}$ jets with large separation in pseudo-rapidity, in opposite
hemispheres, and with large dijet mass. The LHC could discover compressed top
squarks with mass up to approximately 340 GeV (390 GeV) with an integrated
luminosity of 1000 ifb (3000 ifb).


title: Improving self-calibration

abstract:
  Response calibration is the process of inferring how much the measured data
depend on the signal one is interested in. It is essential for any quantitative
signal estimation on the basis of the data. Here, we investigate
self-calibration methods for linear signal measurements and linear dependence
of the response on the calibration parameters. The common practice is to
augment an external calibration solution using a known reference signal with an
internal calibration on the unknown measurement signal itself. Contemporary
self-calibration schemes try to find a self-consistent solution for signal and
calibration by exploiting redundancies in the measurements. This can be
understood in terms of maximizing the joint probability of signal and
calibration. However, the full uncertainty structure of this joint probability
around its maximum is thereby not taken into account by these schemes.
Therefore better schemes -- in sense of minimal square error -- can be designed
by accounting for asymmetries in the uncertainty of signal and calibration. We
argue that at least a systematic correction of the common self-calibration
scheme should be applied in many measurement situations in order to properly
treat uncertainties of the signal on which one calibrates. Otherwise the
calibration solutions suffer from a systematic bias, which consequently
distorts the signal reconstruction. Furthermore, we argue that non-parametric,
signal-to-noise filtered calibration should provide more accurate
reconstructions than the common bin averages and provide a new, improved
self-calibration scheme. We illustrate our findings with a simplistic numerical
example.

categories: astro-ph.IM cs.IT math.IT physics.data-an stat.ML


title:
Yang-Mills mass gap, Floer homology, glueball spectrum, and conformal
  window in large-N QCD

abstract:
  Morse-Smale-Floer homology associates the critical points of the action
functional of a classical field theory over a manifold to its homology. We
associate to the intersection homology of certain Lagrangian submanifolds of
R^4 the critical points of a quantum effective action of large-N SU(N) YM. For
this purpose we construct in YM a trivial Topological Field Theory defined by
twistor Wilson loops whose v.e.v. is 1 in the large-N limit for any shape of
the loops supported on certain punctured Lagrangian submanifolds. We derive a
new holomorphic loop equation for the twistor Wilson loops, that involves the
change of variables in the YM functional integral from the connection to the
anti-selfdual part of the curvature and the choice of a holomorphic gauge.
Employing the holomorphic loop equation, and viewing Floer homology the other
way around, we associate to arcs asymptotic in both directions to the cusps of
the Lagrangian submanifolds the critical points of an effective action, that
turn out to be surface operators of Z(N) holonomy. At the next-to-leading 1/N
order a certain correlator of surface operators is non-topological and
non-trivial, controls the mass gap of YM theory, and is saturated by an
infinite sum of pure poles of scalar and pseudoscalar glueballs with positive
charge conjugation. It satisfies asymptotically for large momentum fundamental
universal constraints arising from the asymptotic freedom and the
renormalization group. We predict at large-N the ratio of the masses of the two
lower-mass scalar glueballs r=\sqrt 2=1.414, to be compared with the measure in
lattice SU(8) YM by Meyer-Teper r=1.42(11), and with the value implied by
PDG(2014) r=1.397(008). The construction extends to massless Veneziano large-N
limit of QCD, for which we determine the lower edge of the conformal window
N_f/N=5/2 and the corresponding quark-mass anomalous dimension gamma=-4/5.


title:
Kinetic theory of nonlinear diffusion in a weakly disordered nonlinear
  Schr\"odinger chain in the regime of homogeneous chaos

abstract:
  We study the discrete nonlinear Schr\"oinger equation with weak disorder,
focusing on the regime when the nonlinearity is, on the one hand, weak enough
for the normal modes of the linear problem to remain well resolved, but on the
other, strong enough for the dynamics of the normal mode amplitudes to be
chaotic for almost all modes. We show that in this regime and in the limit of
high temperature, the macroscopic density $\rho$ satisfies the nonlinear
diffusion equation with a density-dependent diffusion coefficient,
$D(\rho)=D_0\rho^2$. An explicit expression for $D_0$ is obtained in terms of
the eigenfunctions and eigenvalues of the linear problem, which is then
evaluated numerically. The role of the second conserved quantity (energy) in
the transport is also quantitatively discussed.


title:
Absolute properties of the eclipsing binary system AQ Serpentis: A
  stringent test of convective core overshooting in stellar evolution models

abstract:
  We report differential photometric observations and radial-velocity
measurements of the detached, 1.69-day period, double-lined eclipsing binary AQ
Ser. Accurate masses and radii for the components are determined to better than
1.8% and 1.1%, respectively, and are M1 = 1.417 +/- 0.021 MSun, M2 = 1.346 +/-
0.024 MSun, R1 = 2.451 +/- 0.027 RSun, and R2 = 2.281 +/- 0.014 RSun. The
temperatures are 6340 +/- 100 K (spectral type F6) and 6430 +/- 100 K (F5),
respectively. Both stars are considerably evolved, such that predictions from
stellar evolution theory are particularly sensitive to the degree of extra
mixing above the convective core (overshoot). The component masses are
different enough to exclude a location in the H-R diagram past the point of
central hydrogen exhaustion, which implies the need for extra mixing. Moreover,
we find that current main-sequence models are unable to match the observed
properties at a single age even when allowing the unknown metallicity, mixing
length parameter, and convective overshooting parameter to vary freely and
independently for the two components. The age of the more massive star appears
systematically younger. AQ Ser and other similarly evolved eclipsing binaries
showing the same discrepancy highlight an outstanding and largely overlooked
problem with the description of overshooting in current stellar theory.


title: Rescuing Quadratic Inflation

abstract:
  Inflationary models based on a single scalar field $\phi$ with a quadratic
potential $V = \frac{1}{2} m^2 \phi^2$ are disfavoured by the recent Planck
constraints on the scalar index, $n_s$, and the tensor-to-scalar ratio for
cosmological density perturbations, $r_T$. In this paper we study how such a
quadratic inflationary model can be rescued by postulating additional fields
with quadratic potentials, such as might occur in sneutrino models, which might
serve as either curvatons or supplementary inflatons. Introducing a second
scalar field reduces but does not remove the pressure on quadratic inflation,
but we find a sample of three-field models that are highly compatible with the
Planck data on $n_s$ and $r_T$. We exhibit a specific three-sneutrino example
that is also compatible with the data on neutrino mass difference and mixing
angles.


title: Log-transforming the matter power spectrum

abstract:
  We investigate whether non-linear effects on the large-scale power spectrum
of dark matter, namely the increase in small-scale power and the smearing of
baryon acoustic oscillations, can be decreased by a log-transformation or
emulated by an exponential transformation of the linear spectrum. To that end
we present a formalism to convert the power spectrum of a log-normal field to
the power spectrum of the logarithmic Gaussian field and vice versa. All
ingredients of our derivation can already be found in various publications in
cosmology and other fields. We follow a more pedagogical approach providing a
detailed derivation, application examples, and a discussion of implementation
subtleties in one text. We use the formalism to show that the non-linear
increase in small-scale power in the matter power spectrum is significantly
smaller for the log-transformed spectrum which fits the linear spectrum (with
less than 20% error) for redshifts down to 1 and $k\leq1.0\,h\,\mathrm{Mpc}$.
For lower redshifts the fit to the linear spectrum is not as good, but the
reduction of non-linear effects is still significant. Similarly, we show that
applying the linear growth factor to the logarithmic density leads to an
automatic increase in small-scale power for low redshifts fitting to
third-order perturbation spectra and Cosmic Emulator spectra with an error of
less than $20%$. Smearing of baryon acoustic oscillations is at least three
times weaker, but still present.


title: The Earth's velocity for direct detection experiments

abstract:
  The Earth's velocity relative to the Sun in galactic coordinates is required
in the rate calculation for direct detection experiments. We provide a rigorous
derivation of this quantity to first order in the eccentricity of the Earth's
orbit. We also discuss the effect of the precession of the equinoxes, which has
hitherto received little explicit discussion. Comparing with other expressions
in the literature, we confirm that the expression of Lee, Lisanti and Safdi is
correct, while the expression of Lewin and Smith, the de facto standard
expression, contains an error. For calculations of the absolute event rate, the
leading order expression is sufficient while for modulation searches, an
expression with the eccentricity is required for accurate predictions of the
modulation phase.


title:
Quantum Fisher Information: Variational principle and simple iterative
  algorithm for its efficient computation

abstract:
  We derive a new variational principle for the quantum Fisher information
leading to a simple iterative alternating algorithm, the convergence of which
is proved. The case of a fixed measurement, i.e. the classical Fisher
information, is also discussed.


title:
Simulating the universe(s): from cosmic bubble collisions to
  cosmological observables with numerical relativity

abstract:
  The theory of eternal inflation in an inflaton potential with multiple vacua
predicts that our universe is one of many bubble universes nucleating and
growing inside an ever-expanding false vacuum. The collision of our bubble with
another could provide an important observational signature to test this
scenario. We develop and implement an algorithm for accurately computing the
cosmological observables arising from bubble collisions directly from the
Lagrangian of a single scalar field. We first simulate the collision spacetime
by solving Einstein's equations, starting from nucleation and ending at
reheating. Taking advantage of the collision's hyperbolic symmetry, simulations
are performed with a 1+1-dimensional fully relativistic code that uses adaptive
mesh refinement. We then calculate the comoving curvature perturbation in an
open Friedmann-Robertson-Walker universe, which is used to determine the
temperature anisotropies of the cosmic microwave background radiation. For a
fiducial Lagrangian, the anisotropies are well described by a power law in the
cosine of the angular distance from the center of the collision signature. For
a given form of the Lagrangian, the resulting observational predictions are
inherently statistical due to stochastic elements of the bubble nucleation
process. Further uncertainties arise due to our imperfect knowledge about
inflationary and pre-recombination physics. We characterize observational
predictions by computing the probability distributions over four
phenomenological parameters which capture these intrinsic and model
uncertainties. This represents the first fully-relativistic set of predictions
from an ensemble of scalar field models giving rise to eternal inflation,
yielding significant differences from previous non-relativistic approximations.
Thus, our results provide a basis for a rigorous confrontation of these
theories with cosmological data.


title:
On the contribution of active galactic nuclei to reionization (Research
  Note)

abstract:
  The electron scattering optical depth constraints on reionization suggest
that there may be other sources that contribute to the ionization of hydrogen
aside from observable star forming galaxies. Often the calculated value of the
electron scattering optical depth, \tau_{es}, falls below the measurements
derived from observations of the CMB or an assumption about non-observable
sources must be made in order to reach agreement. Here, we calculate the
hydrogen ionization fraction as a function of redshift and the electron
scattering optical depth from both galaxies and active galactic nuclei (AGN)
factoring in the secondary collisional ionizations from the AGN X-ray emission.
In this paper we use the most current determination of the evolving hard X-ray
luminosity function and extrapolate its evolution beyond z = 6. The AGN
spectral energy distributions (SEDs) include both UV and X-ray ionizing
photons. To search for the largest possible effect, all AGN are assumed to have
\lambda_{Edd} = 1.0 and be completely unobscured. The results show that AGNs
produce a perturbative effect on the reionization of hydrogen and remains in
agreement with current constraints. Our calculations find the epoch of
reionization still ends at z \approx 6 and only increases the electron
scattering optical depth by ~2.3% under the most optimal conditions. This can
only be moderately increased by assuming a constant black hole mass of M_{BH} =
10^(5) solar masses. As a result, we conclude that there is a need for other
sources beyond observable galaxies and AGNs that contribute to the reionization
of hydrogen at z > 6.


title:
Extensions of Representable Positive Linear Functionals to Unitized
  Quasi *-Algebras

abstract:
  It is known that, under certain conditions, *-representability and
extensibility to the unitized *-algebra of a positive linear functional,
defined on a *-algebra without unit, are equivalent. In this paper, a new
condition for an analogous result is given for the case of a hermitian linear
functional defined on a quasi *-algebra $(\A,\Ao)$ without unit.


title:
A Search for Methane in the Atmosphere of GJ 1214b via GTC Narrow-Band
  Transmission Spectrophotometry

abstract:
  We present narrow-band photometric measurements of the exoplanet GJ 1214b
using the 10.4 m Gran Telescopio Canarias (GTC) and the OSIRIS instrument.
Using tuneable filters we observed a total of five transits, three of which
were observed at two wavelengths nearly simultaneously, producing a total of
eight individual light curves, six of these probed the possible existence of a
methane absorption feature in the 8770 - 8850 {\AA} region at high resolution.
We detect no increase in the planet-to-star radius ratio across the methane
feature with a change in radius ratio of $\Delta$R = -0.0007 $\pm$ 0.0017
corresponding to a scale height (H) change of -0.5 $\pm$ 1.2 H across the
methane feature, assuming a hydrogen dominated atmosphere. We find a variety of
water and cloudy atmospheric models fit the data well, but find that cloud-free
models provide poor fits. These observations support a flat transmission
spectrum resulting from the presence of a high-altitude haze or a water-rich
atmosphere, in agreement with previous studies. In this study the observations
are predominantly limited by the photometric quality and the limited number of
data points (resulting from a long observing cadence), which make the
determination of the systematic noise challenging. With tuneable filters
capable of high resolution measurements (R ~ 600 - 750) of narrow absorption
features, the interpretation of our results are also limited by the absence of
high resolution methane models below 1 $\mu$m.


title: Excited spectroscopy of mesons containing charm quarks from lattice QCD

abstract:
  We present highly excited spectra of charmonium, charm-light and
charm-strange mesons using the dynamical anisotropic lattices of the Hadron
Spectrum Collaboration. The use of novel techniques has allowed us to extract
these spectra with a high degree of statistical precision, while also enabling
us to observe states as high as spin-4, states with exotic quantum numbers and
candidate gluonic excitations. We discuss the phenomenology of these spectra,
and also present preliminary results of D{\pi} scattering considering only the
lowest partial wave in the isospin-3/2 channel.


title: Nonextreme de Branges-Rovnyak spaces as models for contractions

abstract:
  The de Branges--Rovnyak spaces are known to provide an alternate functional
model for contractions on a Hilbert space, equivalent to the Sz.-Nagy--Foias
model. The scalar de Branges--Rovnyak spaces $\mathcal{H}(b)$ have essentially
different properties, according to whether the defining function $b$ is or not
extreme in the unit ball of $H^\infty$. For $b$ extreme the model space is just
$\mathcal{H}(b)$, while for $b$ nonextreme an additional construction is
required. In the present paper we identify the precise class of contractions
which have as a model $\mathcal{H}(b)$ with $b$ nonextreme.


title: Dark matter detection in two easy steps

abstract:
  Multi-component dark matter particles may have a more intricate direct
detection signal than simple elastic scattering on nuclei. In a broad class of
well-motivated models the inelastic excitation of dark matter particles is
followed by de-excitation via $\gamma$-decay. In experiments with fine energy
resolution, such as many $0\nu 2\beta$ decay experiments, this motivates a
highly model-independent search for the sidereal daily modulation of an
unexpected $\gamma$ line. Such a signal arises from two-step WIMP interaction:
the WIMP is first excited in the lead shielding and subsequently decays back to
the ground state via the emission of a monochromatic $\gamma$ within the
detector volume. We explore this idea in detail by considering the model of
magnetic inelastic WIMPs, and take a sequence of CUORE-type detectors as an
example. We find that under reasonable assumptions about detector performance
it is possible to efficiently explore mass splittings of up to few hundreds of
keV for a WIMP of weak-scale mass and transitional magnetic moments. The
modulation can be cheaply and easily enhanced by the presence of additional
asymmetric lead shielding. We devise a toy simulation to show that a specially
designed asymmetric shielding may result in up to $30\%$ diurnal modulations of
the two-step WIMP signal, leading to additional strong gains in sensitivity.


title:
Computation of the Halo Mass Function Using Physical Collapse
  Parameters: Application to Non-Standard Cosmologies

abstract:
  In this article we compare the halo mass function predicted by the excursion
set theory with a drifting diffusive barrier against the results of N-body
simulations for several cosmological models. This includes the standard LCDM
case for a large range of halo masses, models with different types of
primordial non-Gaussianity, and the Ratra-Peebles quintessence model of Dark
Energy. We show that in all those cosmological scenarios, the abundance of dark
matter halos can be described by a drifting diffusive barrier, where the two
parameters describing the barrier have physical content. In the case of the
Gaussian LCDM, the statistics are precise enough to actually predict those
parameters at different redshifts from the initial conditions. Furthermore, we
found that the stochasticity in the barrier is nonnegligible making the simple
deterministic spherical collapse model a bad approximation even at very high
halo masses. We also show that using the standard excursion set approach with a
barrier inspired by peak patches leads to inconsistent predictions of the halo
mass function.


title: Observational Constraints From Binary Stars on Stellar Evolution Models

abstract:
  Accurate determinations of masses and radii in binary stars, along with
estimates of the effective temperatures, metallicities, and other properties,
have long been used to test models of stellar evolution. As might be expected,
observational constraints are plentiful for main-sequence stars, although some
problems with theory remain even in this regime. Models in other areas of the
H-R diagram are considerably less well constrained, or not constrained at all.
I summarize the status of the field, and provide examples of how accurate
measurements can supply stringent tests of stellar theory, including aspects
such as the treatment of convection. I call attention to the apparent failure
of current models to match the properties of stars with masses of 1.1-1.7 MSun
that are near the point of central hydrogen exhaustion, possibly connected with
the simplified treatment of convective core overshooting.


title:
Anisotropies of ultra-high energy cosmic rays diffusing from
  extragalactic sources

abstract:
  We obtain the dipolar anisotropies in the arrival directions of ultra-high
energy cosmic rays diffusing from nearby extragalactic sources. We discuss both
the energy regime of spatial diffusion and the quasi-rectilinear one leading to
just angular diffusion at higher energies. We obtain analytic results for the
anisotropies from a single source which are validated using two different
numerical simulations. For a scenario with a few sources in the local
supercluster (with the closest source at a typical distance of few to tens of
Mpc), we discuss the possible transition between the case in which the
anisotropies are dominated by a few sources at energies below few EeV towards
the regime in which many sources contribute at higher energies. The effect of a
non-isotropic source distribution is also discussed, showing that it can
significantly affect the observed dipole.


title: On Gravitational Entropy of de Sitter Universe

abstract:
  The paper deals with the calculation of the gravitational entropy in the
context of teleparallel gravity for de Sitter space-time. In such a theory it
is possible to define gravitational energy and pressure, thus we use those
expressions to construct the gravitational entropy. We interpret the
cosmological constant as the temperature and write the first law of
thermodynamics. In the limit $\Lambda\ll 1$ we find that the entropy is
proportional to volume and $\Delta S\geq 0$.


title:
Noncommutative Quantum Mechanics based in Representations of Exotic
  Galilei Group

abstract:
  Using elements of symmetry, we constructed the Noncommutative Schr\"odinger
Equation from a representation of Exotic Galilei Group. As consequence, we
derive the Ehrenfest theorem using noncommutative coordinates. We also have
showed others features of quantum mechanics in such a manifold. As an important
result, we find out that a linear potential in the noncommutative Schr\"odinger
equation is completely analogous to the ordinary case. We also worked with
harmonic and anharmonic oscillators, giving corrections in the energy for each
one.


title:
Quasi-Polynomial Time Approximation Scheme for Sparse Subsets of
  Polygons

abstract:
  We describe how to approximate, in quasi-polynomial time, the largest
independent set of polygons, in a given set of polygons. Our algorithm works by
extending the result of Adamaszek and Wiese \cite{aw-asmwi-13, aw-qmwis-14} to
polygons of arbitrary complexity. Surprisingly, the algorithm also works or
computing the largest subset of the given set of polygons that has some
sparsity condition. For example, we show that one can approximate the largest
subset of polygons, such that the intersection graph of the subset does not
contain a cycle of length $4$ (i.e., $K_{2,2}$).


title: On Non-commutative Geodesic Motion

abstract:
  In this work we study the geodesic motion on a noncommutative space-time. As
a result we find a non-commutative geodesic equation and then we derive
corrections of the deviation angle per revolution in terms of the
non-commutative parameter when we specify the problem of Mercury's perihelion.
In this way, we estimate the noncommutative parameter based in experimental
data.


title: Rigged Hilbert spaces and contractive families of Hilbert spaces

abstract:
  The existence of a rigged Hilbert space whose extreme spaces are,
respectively, the projective and the inductive limit of a directed contractive
family of Hilbert spaces is investigated. It is proved that, when it exists,
this rigged Hilbert space is the same as the canonical rigged Hilbert space
associated to a family of closable operators in the central Hilbert space.


title: Tidal Flows in asynchronous binaries: The beta-factor

abstract:
  We discuss the potential role that tidal flows in asynchronous binary stars
may play in transporting chemically enriched material from deep layers towards
the surface and the corresponding observational consequences of these
processes. We suggest that the time-dependent velocity field induced by
asynchronous rotation may contribute significantly to the mixing, thus
providing a channel for the formation of chemically enriched slowly rotating
massive stars.


title:
A Comparison of Fick and Maxwell-Stefan Diffusion Formulations in PEMFC
  Cathode Gas Diffusion Layers

abstract:
  This paper explores the mathematical formulations of Fick and Maxwell-Stefan
diffusion in the context of polymer electrolyte membrane fuel cell cathode gas
diffusion layers. Formulations of diffusion combined with mass-averaged Darcy
flow are considered for three component gases. Fick formulations can be
considered as approximations of Maxwell-Stefan in a certain sense. For this
application, the formulations can be compared computationally in a simple, one
dimensional setting. We observe that the predictions of the formulations are
very similar, despite their seemingly different structure. Analytic insight is
given to the result. In addition, it is seen that for both formulations,
diffusion laws are small perturbations from bulk flow. The work is also
intended as a reference to multi-component gas diffusion formulations in the
fuel cell setting.


title: A swirling flare-related EUV jet

abstract:
  {We report our observations of a swirling flare-related EUV jet on 2011
October 15.} {We utilised the EUV observations from SDO/AIA. We extracted a
wide slit along the jet axis and 12 thin slits across its axis to investigate
the longitudinal motion and transverse rotation. We also used data from
STEREO/EUVI to investigate the 3D structure of the jet. Gound-based H$\alpha$
images provide a good opportunity to explore the relationship between the cool
surge and hot jet. LOS magnetograms from SDO/HMI enable us to study the
magnetic evolution of the flare/jet event.} {The onset of jet eruption
coincided with the start time of C1.6 flare impulsive phase. The initial
velocity and acceleration of the longitudinal motion were 254$\pm10$ km
s$^{-1}$ and $-97\pm5$ m s$^{-2}$, respectively. The jet presented helical
structure and transverse swirling motion at the beginning of its eruption. The
counter-clockwise rotation slowed down from an average velocity of $\sim$122 km
s$^{-1}$ to $\sim$80 km s$^{-1}$. The interwinding thick threads of the jet
untwisted into multiple thin threads during the rotation that lasted for 1
cycle with a period of $\sim$7 min and an amplitude that increases from
$\sim$3.2 Mm at the bottom to $\sim$11 Mm at the upper part. Afterwards, the
curtain-like leading edge of the jet continued rising without rotation, leaving
a dimming region behind before falling back to the solar surface. The
appearance/disappearance of dimming corresponded to the longitudinal
ascending/descending motions of jet. Cospatial H$\alpha$ surge and EUV dimming
imply that the dimming resulted from the absorption of hot EUV emission by cool
surge. The flare/jet event was caused by continuous magnetic cancellation
before the start of flare. The jet was associated with the open magnetic fields
at the edge of AR 11314.}


title:
Impact of receiver reaction mechanisms on the performance of molecular
  communication networks

abstract:
  In a molecular communication network, transmitters and receivers communicate
by using signalling molecules. At the receivers, the signalling molecules
react, via a chain of chemical reactions, to produce output molecules. The
counts of output molecules over time is considered to be the output signal of
the receiver. This output signal is used to detect the presence of signalling
molecules at the receiver. The output signal is noisy due to the stochastic
nature of diffusion and chemical reactions. The aim of this paper is to
characterise the properties of the output signals for two types of receivers,
which are based on two different types of reaction mechanisms. We derive
analytical expressions for the mean, variance and frequency properties of these
two types of receivers. These expressions allow us to study the properties of
these two types of receivers. In addition, our model allows us to study the
effect of the diffusibility of the receiver membrane on the performance of the
receivers.


title: From M-theory higher curvature terms to \alpha' corrections in F-theory

abstract:
  We perform a Kaluza-Klein reduction of eleven-dimensional supergravity on a
Calabi-Yau fourfold including terms quartic and cubic in the Riemann curvature
and determine the induced corrections to the three-dimensional N=2 effective
action. We focus on the effective Einstein-Hilbert term and the kinetic terms
for vectors. Dualizing the vectors into scalars, we derive the resulting Kahler
potential and complex coordinates. The classical expressions for the Kahler
coordinates are non-trivially modified, while the functional form of the Kahler
potential is shown to be uncorrected. For elliptically fibered Calabi-Yau
fourfolds the corrections can be uplifted to a four-dimensional F-theory
compactification. We argue that also the four-dimensional N=1 Kahler
coordinates receive non-trivial corrections. We find a simple expression for
the induced corrections for different Abelian and non-Abelian seven-brane
configurations by scanning over many Calabi-Yau fourfolds with resolved
singularities. The interpretation of this expression leads us to conjecture
that the higher-curvature corrections correspond to \alpha'^2 corrections that
arise from open strings at the self-intersection of seven-branes.


title: Klein Paradox in the Pilot Wave Interpretation

abstract:
  The de Broglie-Bohm pilot wave interpretation of quantum mechanics is shown
to provide a consistent explanation for a single relativistic particle (more
accurately, a single particle process since pair production is addressed). This
is accomplished by incorporating the Feynman-Stueckelberg interpretation of
anti-matter. The lack of conserved probability and existence of negative energy
solutions is studied through this interpretation. We discuss the resolution of
Klein's original paradox through the pilot wave interpretation, and similarly
analyze the potential barrier problem. Simulations are presented for a wave
packet incident on potential steps & barriers of various heights.


title: An Analytical Model for Loc/ID Mappings Caches

abstract:
  Concerns regarding the scalability of the inter-domain routing have
encouraged researchers to start elaborating a more robust Internet
architecture. While consensus on the exact form of the solution is yet to be
found, the need for a semantic decoupling of a node's location and identity is
generally accepted as a promising way forward. However, this typically requires
the use of caches that store temporal bindings between the two namespaces, to
avoid hampering router packet forwarding speeds. In this article, we propose a
methodology for an analytical analysis of cache performance that relies on the
working-set theory. We first identify the conditions that network traffic must
comply with for the theory to be applicable and then develop a model that
predicts average cache miss rates relying on easily measurable traffic
parameters. We validate the result by emulation, using real packet traces
collected at the egress points of a campus and an academic network. To prove
its versatility, we extend the model to consider cache polluting user traffic
and observe that simple, low intensity attacks drastically reduce performance,
whereby manufacturers should either overprovision router memory or implement
more complex cache eviction policies.


title: Criticality of counterexamples to toroidal edge-hamiltonicity

abstract:
  A well-known conjecture of Gr\"unbaum and Nash-Williams proposes that
4-connected toroidal graphs are hamiltonian. The corresponding results for
4-connected planar and projective-planar graphs were proved by Tutte and by
Thomas and Yu, respectively, using induction arguments that proved a stronger
result, that every edge is on a hamilton cycle. However, this stronger property
does not hold for 4-connected toroidal graphs: Thomassen constructed
counterexamples. Thus, the standard inductive approach will not work for the
torus. One possible way to modify it is by characterizing the situations where
some edge is not on a hamilton cycle. We provide a contribution in this
direction, by showing that the obvious generalizations of Thomassen's
counterexamples are critical in a certain sense.


title:
Proportionality of components, Liouville theorems and a priori estimates
  for noncooperative elliptic systems

abstract:
  We study qualitative properties of positive solutions of noncooperative,
possibly nonvariational, elliptic systems. We obtain new classification and
Liouville type theorems in the whole Euclidean space, as well as in
half-spaces, and deduce a priori estimates and existence of positive solutions
for related Dirichlet problems. We significantly improve the known results for
a large class of systems involving a balance between repulsive and attractive
terms. This class contains systems arising in biological models of
Lotka-Volterra type, in physical models of Bose-Einstein condensates and in
models of chemical reactions.


title:
Depolarized light scattering and dielectric response of a peptide
  dissolved in water

abstract:
  The density and orientational relaxation of bulk water can be separately
studied by depolarized light scattering (DLS) and dielectric spectroscopy (DS),
respectively. Here we ask the question of what are the leading collective modes
responsible for polarization anisotropy relaxation (DLS) and dipole moment
relaxation (DS) of solutions involving mostly hydrophobic solute-water
interfaces. We study, by atomistic molecular dynamics simulations, the dynamics
and structure of hydration water interfacing N-Acetyl-leucine-methylamide
(NALMA) dipeptide. The DLS response of the solution is consistent with three
relaxation processes: bulk water, rotations of single solutes, and collective
dipole-induced-dipole polarizability of the solutes, with the time-scale of
130-200 ps. No separate DLS response of the hydration shell has been identified
by our simulations. Density fluctuations of the hydration layer, which largely
contribute to the response, do not produce a dynamical process distinct from
bulk water. We find that the structural perturbation of the orientational
distribution of hydration waters by the dipeptide solute is quite significant
and propagates 3-5 hydration layers into the bulk. This perturbation is still
below that produced by hydrated globular proteins. Despite this structural
perturbation, there is little change in the orientational dynamics of the
hydration layers, compared to the bulk, as probed by both single-particle
orientational dynamics and collective dynamics of the dipole moment of the
shells. There is a clear distinction between the perturbation of the
interfacial structure by the solute-solvent interaction potential and the
perturbation of the interfacial dynamics by the corresponding forces.


title: Orienting Fully Dynamic Graphs with Worst-Case Time Bounds

abstract:
  In edge orientations, the goal is usually to orient (direct) the edges of an
undirected $n$-vertex graph $G$ such that all out-degrees are bounded. When the
graph $G$ is fully dynamic, i.e., admits edge insertions and deletions, we wish
to maintain such an orientation while keeping a tab on the update time. Low
out-degree orientations turned out to be a surprisingly useful tool, with
several algorithmic applications involving static or dynamic graphs.
  Brodal and Fagerberg (1999) initiated the study of the edge orientation
problem in terms of the graph's arboricity, which is very natural in this
context. They provided a solution with constant out-degree and \emph{amortized}
logarithmic update time for all graphs with constant arboricity, which include
all planar and excluded-minor graphs. However, it remained an open question
(first proposed by Brodal and Fagerberg, later by others) to obtain similar
bounds with worst-case update time.
  We resolve this 15 year old question in the affirmative, by providing a
simple algorithm with worst-case bounds that nearly match the previous
amortized bounds. Our algorithm is based on a new approach of a combinatorial
invariant, and achieves a logarithmic out-degree with logarithmic worst-case
update times. This result has applications in various dynamic graph problems
such as maintaining a maximal matching, where we obtain $O(\log n)$ worst-case
update time compared to the $O(\frac{\log n}{\log\log n})$ amortized update
time of Neiman and Solomon (2013).


title: Apollonian circle packings: Dynamics and Number theory

abstract:
  We give an overview of various counting problems for Apollonian circle
packings, which turn out to be related to problems in dynamics and number
theory for thin groups. This survey article is an expanded version of my
lecture notes prepared for the 13th Takagi lectures given at RIMS, Kyoto in the
fall of 2013.


title: Total diameter and area of closed submanifolds

abstract:
  The total diameter of a closed planar curve $C\subset R^2$ is the integral of
its antipodal chord lengths. We show that this quantity is bounded below by
twice the area of $C$. Furthermore, when $C$ is convex or centrally symmetric,
the lower bound is twice as large. Both inequalities are sharp and the equality
holds in the convex case only when $C$ is a circle. We also generalize these
results to $m$ dimensional submanifolds of $R^n$, where the "area" will be
defined in terms of the mod $2$ winding numbers of the submanifold about the
$n-m-1$ dimensional affine subspaces of $R^n$.


title:
The Mellon Fedora Project: Digital Library Architecture Meets XML and
  Web Services

abstract:
  The University of Virginia received a grant of $1,000,000 from the Andrew W.
Mellon Foundation to enable the Library, in collaboration with Cornell
University, to build a digital object repository system based on the Flexible
Extensible Digital Object and Repository Architecture (Fedora). The new system
demonstrates how distributed digital library architecture can be deployed using
web-based technologies, including XML and Web services. The new system is
designed to be a foundation upon which interoperable web-based digital
libraries can be built. Virginia and collaborating partners in the US and UK
will evaluate the system using a diverse set of digital collections. The
software will be made available to the public as an open-source release.


title: Conformal scattering on the Schwarzschild metric

abstract:
  We show that existing decay results for scalar fields on the Schwarzschild
metric are sufficient to obtain a conformal scattering theory. Then we
re-interpret this as an analytic scattering theory defined in terms of wave
operators, with an explicit comparison dynamics associated with the principal
null geodesic congruences. The case of the Kerr metric is also discussed.


title: Decomposable stationary distribution of a multidimensional SRBM

abstract:
  We call a multidimensional distribution to be decomposable with respect to a
partition of two sets of coordinates if the original distribution is the
product of the marginal distributions associated with these two sets. We focus
on the stationary distribution of a multidimensional semimartingale reflecting
Brownian motion (SRBM) on a nonnegative orthant. An SRBM is uniquely determined
(in distribution) by its data that consists of a covariance matrix, a drift
vector, and a reflection matrix. Assume that the stationary distribution of an
SRBM exists. We first characterize two marginal distributions under the
decomposability assumption. We prove that they are the stationary distributions
of some lower dimensional SRBMs. We also identify the data for these lower
dimensional SRBMs. Thus, under the decomposability assumption, we can obtain
the stationary distribution of the original SRBM by computing those of the
lower dimensional ones. However, this characterization of the marginal
distributions is not sufficient for the decomposability. So, we next consider
necessary and sufficient conditions for the decomposability. We obtain those
conditions for several classes of SRBMs. These classes include SRBMs arising
from Brownian models of queueing networks that have two sets of stations with
feed-forward routing between these two sets. This work is motivated by
applications of SRBMs and geometric interpretations of the product form
stationary distributions.


title: Comment on "Quantum Quasicrystals of Spin-Orbit-Coupled Dipolar Bosons"

abstract:
  In a recent Letter, Gopalakrishnan, Martin, and Demler [Phys. Rev. Lett. 111
(2013) 185304] show that quasi-two-dimensional dipolar Bose gases, subject to a
Rashba spin-orbit coupling, exhibit a variety of spatially ordered, or
crystalline, ground states, including a pentagonal quasicrystal. Indeed, as the
authors say, realizing quasicrystalline condensates would provide new ways to
explore the physics of quasicrystals, and in particular to study the quantum
dynamics of their unique collective phason modes. Yet, the authors conclude
that "there are typically additional phasons in quantum-mechanical
quasicrystals, when compared with their classical equivalents." In this Comment
I review the notion of phason modes in quasicrystals, and explain why their
number does not depend on whether they are classical or quantum.


title:
Convergence analysis of a fractional time-stepping technique for
  incompressible fluids with microstructure

abstract:
  We present and analyze a fully discrete fractional time stepping technique
for the solution of the micropolar Navier Stokes equations, which is a system
of equations that describes the evolution of an incompressible fluid whose
material particles possess both translational and rotational degrees of
freedom. The proposed scheme uncouples the computation of the linear and
angular velocity and the pressure. It is unconditionally stable and delivers
optimal convergence rates.


title:
An Analysis of Finite Element Approximation in Electrical Impedance
  Tomography

abstract:
  We present a finite element analysis of electrical impedance tomography for
reconstructing the conductivity distribution from electrode voltage
measurements by means of Tikhonov regularization. Two popular choices of the
penalty term, i.e., $H^1(\Omega)$-norm smoothness penalty and total variation
seminorm penalty, are considered. A piecewise linear finite element method is
employed for discretizing the forward model, i.e., the complete electrode
model, the conductivity, and the penalty functional. The convergence of the
finite element approximations for the Tikhonov model on both polyhedral and
smooth curved domains is established. This provides rigorous justifications for
the ad hoc discretization procedures in the literature.


title: High redshift supermassive blackholes: accretion through cold flows

abstract:
  We use zoom-in techniques to re-simulate three high-redshift (z > 5.5) halos
which host 10^9 solar mass blackholes from the ~ Gpc volume, MassiveBlack
cosmological hydrodynamic simulation. We examine a number of factors
potentially affecting supermassive blackhole growth at high redshift in
cosmological simulations. These include numerical resolution, feedback
prescriptions and formulation of smoothed particle hydrodynamics. We find that
varying the size of the region over which feedback energy is deposited
directly, either for fixed number of neighbours or fixed volume makes very
little difference to the accretion history of blackholes. Changing mass
resolution by factors of up to 64 also does not change the blackhole growth
history significantly. We find that switching from the density-entropy
formulation to the pressure-entropy formulation of smoothed particle
hydrodynamics slightly increases the accretion rate onto blackholes. In general
numerical details appear to have small effects on the main fueling mechanism
for blackholes at these high redshifts. We examine the fashion by which this
occurs, finding that the insensitivity to simulation technique seems to be a
hallmark of the cold flow feeding picture of these high-z supermassive
blackholes. We show that the gas that participates in critical accretion
phases, in these massive objects at z > 6~7 is in all cases colder, denser, and
forms more coherent streams than the average gas in the halo. This is also
mostly the case when the blackhole accretion is feedback regulated (z < 6),
however the distinction is less prominent. For our resimulated halos, cold
flows appear to be a viable mechanism for forming the most massive blackholes
in the early universe, occurring naturally in LambdaCDM models of structure
formation. Not requiring fine tuning of numerical parameters, they seem to be
physically inevitable in these objects.