title:
A simple model of complete precessing black-hole-binary gravitational
  waveforms

abstract:
  The construction of a model of the gravitational-wave (GW) signal from
generic configurations of spinning-black-hole binaries, through inspiral,
merger and ringdown, is one of the most pressing theoretical problems in the
build-up to the era of GW astronomy. We present the first such model in the
frequency domain, "PhenomP", which captures the basic phenomenology of the
seven-dimensional parameter space of binary configurations with only three key
physical parameters. Two of these (the binary's mass ratio and an effective
total spin parallel to the orbital angular momentum, which determines the
inspiral rate) define an underlying non-precessing-binary model. The
non-precessing-binary waveforms are then "twisted up" with approximate
expressions for the precessional motion, which require only one additional
physical parameter, an effective precession spin, $\chi_p$. All other
parameters (total mass, sky location, orientation and polarisation, and initial
phase) can be specified trivially. The model is constructed in the frequency
domain, which will be essential for efficient GW searches and source
measurements. We have tested the model's fidelity for GW applications by
comparison against hybrid post-Newtonian-numerical-relativity waveforms at a
variety of configurations --although we did not use these numerical simulations
in the construction of the model. Our model can be used to develop GW searches,
to study the implications for astrophysical measurements, and as a simple
conceptual framework to form the basis of generic-binary waveform modelling in
the advanced-detector era.


title:
Space-Time Interference Alignment and Degrees of Freedom Regions for the
  MISO Broadcast Channel with Periodic CSI Feedback

abstract:
  This paper characterizes the degrees of freedom (DoF) regions for the
multi-user vector broadcast channel with periodic channel state information
(CSI) feedback. As a part of the characterization, a new transmission method
called space-time interference alignment is proposed, which exploits both the
current and past CSI jointly. Using the proposed alignment technique, an inner
bound of the sum-DoF region is characterized as a function of a normalized CSI
feedback frequency, which measures CSI feedback speed compared to the speed of
user's channel variations. One consequence of the result is that the achievable
sum-DoF gain is improved significantly when a user sends back both current and
outdated CSI compared to the case where the user sends back current CSI only.
Then, a trade-off between CSI feedback delay and the sum-DoF gain is
characterized for the multi-user vector broadcast channel in terms of a
normalized CSI feedback delay that measures CSI obsoleteness compared to
channel coherence time. A crucial insight is that it is possible to achieve the
optimal DoF gain if the feedback delay is less than a derived fraction of the
channel coherence time. This precisely characterizes the intuition that a small
delay should be negligible.


title:
Nuclear Jacobi and Poincar\'e Transitions at High Spins and
  Temperatures: Account~of~Dynamic~Effects~and~Large-Amplitude Motion

abstract:
  We present a theoretical analysis of the competition between so-called
nuclear Jacobi and Poincar\'e shape transitions in function of spin - at high
temperatures. The latter condition implies the method of choice - a realistic
version of the nuclear Liquid Drop Model (LDM), here: the Lublin-Strasbourg
Drop (LSD) model. We address specifically the fact that the Jacobi and
Poincar\'e shape transitions are accompanied by the flattening of total nuclear
energy landscape as function of the relevant deformation parameters what
enforces large amplitude oscillation modes that need to be taken into account.
For that purpose we introduce an approximate form of the collective
Schr\"odinger equation whose solutions are used to calculate the most probable
deformations associated with both types of transitions and discuss the physical
consequences in terms of the associated critical-spin values and transitions
themselves.


title: Stochastic incompressible Euler equations in a two-dimensional domain

abstract:
  The aim of these notes is to give an overview of the current results about
existence and uniqueness of solutions for the stochastic Euler equation driven
by a Brownian noise in a two-dimensional bounded domain.


title:
The second quantization method for indistinguishable particles (Lecture
  Notes in Physics, UFABC 2010)

abstract:
  Contents
  1. Creation and annihilation operators for the system of indistinguishable
particles 1.1 The permutation group and the states of a system of
indistinguishable particles 1.2 Dimension of the Hilbert space of a system of
indistinguishable particles 1.3 Definition and properties of the creation and
annihilation operators 1.4 TheFockspace 1.5 The representations of state
vectors and operators 1.5.1 N-particlewave-functions 1.5.2 The
second-quantization representation of operators 1.5.3 Examples 1.6 Evolution of
operators in the Heisenberg picture 1.7 Statistical operators of
indistinguishable particles 1.7.1 The averages of the s-particle operators
1.7.2 The general structure of the one-particle statistical operator 2
Quadratic Hamiltonian and the diagonalization 2.1 Diagionalization of the
Hamiltonian quadratic in the fermion operators 2.2 Diagionalization of the
Hamiltonian quadratic in the boson operators 2.2.1 Diagonalization of the
quadratic bosonic Hamiltonian possessing a zero mode 2.3 Long range order,
condensation and the Bogoliubov spectrum of weakly interacting Bose gas 2.3.1
The excitation spectrum of weakly interacting Bose gas inabox 2.3.2 The
excitation spectrum of an interacting Bose gas in an externalpotential 2.4 The
Jordan-Wigner transformation: fermionization of interacting 1D spin chains


title:
Proper orthogonal decomposition closure models for fluid flows: Burgers
  equation

abstract:
  This paper puts forth several closure models for the proper orthogonal
decomposition (POD) reduced order modeling of fluid flows. These new closure
models, together with other standard closure models, are investigated in the
numerical simulation of the Burgers equation. This simplified setting
represents just the first step in the investigation of the new closure models.
It allows a thorough assessment of the performance of the new models, including
a parameter sensitivity study. Two challenging test problems displaying moving
shock waves are chosen in the numerical investigation. The closure models and a
standard Galerkin POD reduced order model are benchmarked against the fine
resolution numerical simulation. Both numerical accuracy and computational
efficiency are used to assess the performance of the models.


title: Astrogenomics: big data, old problems, old solutions?

abstract:
  The ominous warnings of a `data deluge' in the life sciences from
high-throughput DNA sequencing data are being supplanted by a second deluge, of
cliches bemoaning our collective scientific fate unless we address the genomic
data `tsunami'. It is imperative that we explore the many facets of the genome,
not just sequence but also transcriptional and epigenetic variability,
integrating these observations in order to attain a genuine understanding of
how genes function, towards a goal of genomics-based personalized medicine.
Determining any individual's genomic properties requires comparison to many
others, sifting out the specific from the trends, requiring access to the many
in order to yield information relevant to the few. This is the central big data
challenge in genomics that still requires some sort of resolution. Is there a
practical, feasible way of directly connecting the scientific community to this
data universe? The best answer could be in the stars overhead.


title: The Biggest Explosions in the Universe. II

abstract:
  One of the leading contenders for the origin of supermassive black holes at
$z \gtrsim$ 7 is catastrophic baryon collapse in atomically-cooled halos at $z
\sim$ 15. In this scenario, a few protogalaxies form in the presence of strong
Lyman-Werner UV backgrounds that quench H$_2$ formation in their constituent
halos, preventing them from forming stars or blowing heavy elements into the
intergalactic medium prior to formation. At masses of 10$^ 8$ \Ms\ and virial
temperatures of 10$^4$ K, gas in these halos rapidly cools by H lines, in some
cases forming 10$^4$ - 10$^6$ \Ms\ Pop III stars and, a short time later, the
seeds of supermassive black holes. Instead of collapsing directly to black
holes some of these stars died in the most energetic thermonuclear explosions
in the universe. We have modeled the explosions of such stars in the dense
cores of line-cooled protogalaxies in the presence of cosmological flows. In
stark contrast to the explosions in diffuse regions in previous simulations,
these SNe briefly engulf the protogalaxy but then collapse back into its dark
matter potential. Fallback drives turbulence that efficiently distributes
metals throughout the interior of the halo and fuels the rapid growth of
nascent black holes at its center. The accompanying starburst and x-ray
emission from these line-cooled galaxies easily distinguish them from more
slowly evolving neighbors and might reveal the birthplaces of supermassive
black holes on the sky.


title: Independent Process Approximations for Random Combinatorial Structures

abstract:
  Many random combinatorial objects have a component structure whose joint
distribution is equal to that of a process of mutually independent random
variables, conditioned on the value of a weighted sum of the variables. It is
interesting to compare the combinatorial structure directly to the independent
discrete process, without renormalizing. The quality of approximation can often
be conveniently quantified in terms of total variation distance, for
functionals which observe part, but not all, of the combinatorial and
independent processes.
  Among the examples are combinatorial assemblies (e.g. permutations, random
mapping functions, and partitions of a set), multisets (e.g. polynomials over a
finite field, mapping patterns and partitions of an integer), and selections
(e.g. partitions of an integer into distinct parts, and square-free polynomials
over finite fields).
  We consider issues common to all the above examples, including equalities and
upper bounds for total variation distances, existence of limiting processes,
heuristics for good approximations, the relation to standard generating
functions, moment formulas and recursions for computing densities, refinement
to the process which counts the number of parts of each possible type, the
effect of further conditioning on events of moderate probability, large
deviation theory and nonuniform measures on combinatorial objects, and the
possibility of getting useful results by overpowering the conditioning.


title: Lower bounds for oblivious subspace embeddings

abstract:
  An oblivious subspace embedding (OSE) for some eps, delta in (0,1/3) and d <=
m <= n is a distribution D over R^{m x n} such that for any linear subspace W
of R^n of dimension d,
  Pr_{Pi ~ D}(for all x in W, (1-eps) |x|_2 <= |Pi x|_2 <= (1+eps)|x|_2) >= 1 -
delta.
  We prove that any OSE with delta < 1/3 must have m = Omega((d +
log(1/delta))/eps^2), which is optimal. Furthermore, if every Pi in the support
of D is sparse, having at most s non-zero entries per column, then we show
tradeoff lower bounds between m and s.


title: Hyperbanana Graphs

abstract:
  A bar-and-joint framework is a finite set of points together with specified
distances between selected pairs. In rigidity theory we seek to understand when
the remaining pairwise distances are also fixed. If there exists a pair of
points which move relative to one another while maintaining the given distance
constraints, the framework is flexible; otherwise, it is rigid.
  Counting conditions due to Maxwell give a necessary combinatorial criterion
for generic minimal bar-and-joint rigidity in all dimensions. Laman showed that
these conditions are also sufficient for frameworks in R^2. However, the
flexible "double banana" shows that Maxwell's conditions are not sufficient to
guarantee rigidity in R^3. We present a generalization of the double banana to
a family of hyperbananas. In dimensions 3 and higher, these are
(infinitesimally) flexible, providing counterexamples to the natural
generalization of Laman's theorem.


title: Complete stability analysis of a heuristic ADP control design

abstract:
  This paper provides new stability results for Action-Dependent Heuristic
Dynamic Programming (ADHDP), using a control algorithm that iteratively
improves an internal model of the external world in the autonomous system based
on its continuous interaction with the environment. We extend previous results
by ADHDP control to the case of general multi-layer neural networks with deep
learning across all layers. In particular, we show that the introduced control
approach is uniformly ultimately bounded (UUB) under specific conditions on the
learning rates, without explicit constraints on the temporal discount factor.
We demonstrate the benefit of our results to the control of linear and
nonlinear systems, including the cart-pole balancing problem. Our results show
significantly improved learning and control performance as compared to the
state-of-art.


title:
Magnetic order in pyrochlore iridate Nd$_2$Ir$_2$O$_7$ probed by muon
  spin relaxation

abstract:
  Muon-spin relaxation results on the pyrochlore iridate Nd$_2$Ir$_2$O$_7$ are
reported. Spontaneous coherent muon-spin precession below the metal-insulator
transition (MIT) temperature of about 33 K is observed, indicating the
appearance of a long-ranged magnetic ordering of Ir$^{4+}$ moments. With
further decrease in temperature, the internal field at the muon site increases
again below about 9 K. The second increase of internal field suggests the
ordering of Nd$^{3+}$ moments, which is consistent with a previous neutron
experiment. Our results suggest that the MIT and magnetic ordering of Ir$^{4+}$
moments have a close relationship and that the large spin-orbit coupling of Ir
5\textit{d} electrons plays a key role for both MIT and the mechanism of the
magnetic ordering in pyrochlore iridates in the insulting ground state.


title: Experimentation in the Schubert Calculus

abstract:
  Many aspects of Schubert calculus are easily modeled on a computer. This
enables large-scale experimentation to investigate subtle and ill-understood
phenomena in the Schubert calculus. A well-known web of conjectures and results
in the real Schubert calculus has been inspired by this continuing
experimentation. A similarly rich story concerning intrinsic structure, or
Galois groups, of Schubert problems is also beginning to emerge from
experimentation. This showcases new possibilities for the use of computers in
mathematical research.


title:
Magnetic instability induced by Rh-doping in Kondo semiconductor
  CeRu$_2$Al$_{10}$

abstract:
  Magnetic ground state of Rh-doped Kondo semiconductor CeRu$_2$Al$_{10}$
[Ce(Ru$_{1-x}$Rh$_x$)$_2$Al$_{10}$] is investigated by muon-spin relaxation
method. Muon-spin precession with two frequencies is observed in the $x$ = 0
sample, while only one frequency is present in the $x$ = 0.05 and 0.1 samples,
which is attributed to the broad static field distribution at the muon site.
The internal field at the muon site is enhanced from about 180 G in $x$ = 0
sample to about 800 G in the Rh-doped samples, supporting the spin-flop
transition as suggested by macroscopic measurements, and the boundary of
different magnetic ground states is identified around $x$ = 0.03. The drastic
change of magnetic ground state by a small amount of Rh-doping (3%) indicates
that the magnetic structure in CeRu$_2$Al$_{10}$ is not robust and can be
easily tuned by external perturbations such as electron doping. The anomalous
temperature dependence of internal field in CeRu$_2$Al$_{10}$ is suggested to
be attributed to the hyperfine interaction between muons and conduction
electrons.


title: Normal analytic compactifications of C^2

abstract:
  This is a survey of some results on the structure and classification of
normal analytic compactifications of C^2. Mirroring the existing literature, we
especially emphasize the compactifications for which the curve at infinity is
irreducible.


title: The CHSH-type inequalities for infinite-dimensional quantum systems

abstract:
  By establishing CHSH operators and CHSH-type inequalities, we show that any
entangled pure state in infinite-dimensional systems is entangled in a
$2\otimes2$ subspace. We find that, for infinite-dimensional systems, the
corresponding properties are similar to that of the two-qubit case: (i) The
CHSH-type inequalities provide a sufficient and necessary condition for
separability of pure states; (ii) The CHSH operators satisfy the Cirel'son
inequalities; (iii) Any state which violates one of these Bell inequalities is
distillable.


title:
Ultra-short pulse transmission in a passive white light cavity based on
  chirped Bragg gratings

abstract:
  It is widely accepted that Bragg reflection from linearly chirped Bragg
gratings (LCBGs) can compensate for a chromatic dispersion by reflecting
different wavelengths at different location along the axis of the gratings for
ultra-short pulses. In this paper, we studied the possibility of making use of
such a dispersion-compensating property to construct a white light cavity
(WLC). A pair of LCBGs is suggested as the reflectors of the cavity. The
analytical and numerical analysis shows that the reflection by a LCBG does not
solely occur at the position where Bragg condition is reached. The accumulated
effect of multiple scatterings at different locations inside the LCBG produces
a positive group delay, preventing the WLC to be realized with simple LCBG.


title: Nonlinear Time-Reversal of Classical Waves: Experiment and Model

abstract:
  We consider time-reversal of electromagnetic waves in a closed, wave-chaotic
system containing a discrete, passive, harmonic-generating nonlinearity. An
experimental system is constructed as a time-reversal mirror, in which
excitations generated by the nonlinearity are gathered, time-reversed,
transmitted, and directed exclusively to the location of the nonlinearity. Here
we show that such nonlinear objects can be purely passive (as opposed to the
active nonlinearities used in previous work), and develop a high-rate secure
communication system based on nonlinear time-reversal. A model of the
experimental system is developed, using a star-graph network of transmission
lines, with one of the lines terminated by a model diode. The model simulates
time-reversal of linear and nonlinear signals, demonstrates features seen in
the experimental system, and supports our interpretation of the experimental
results.


title:
An Efficient Coarse Grid Projection Method for Quasigeostrophic Models
  of Large-Scale Ocean Circulation

abstract:
  This paper puts forth a coarse grid projection (CGP) multiscale method to
accelerate computations of quasigeostrophic (QG) models for large scale ocean
circulation. These models require solving an elliptic sub-problem at each time
step, which takes the bulk of the computational time. The method we propose
here is a modular approach that facilitates data transfer with simple
interpolations and uses black-box solvers for solving the elliptic sub-problem
and potential vorticity equations in the QG flow solvers. After solving the
elliptic sub-problem on a coarsened grid, an interpolation scheme is used to
obtain the fine data for subsequent time stepping on the full grid. The
potential vorticity field is then updated on the fine grid with savings in
computational time due to the reduced number of grid points for the elliptic
solver. The method is applied to both single layer barotropic and two-layer
stratified QG ocean models for mid-latitude oceanic basins in the beta plane,
which are standard prototypes of more realistic ocean dynamics. The method is
found to accelerate these computations while retaining the same level of
accuracy in the fine-resolution field. A linear acceleration rate is obtained
for all the cases we consider due to the efficient linear-cost fast Fourier
transform based elliptic solver used. We expect the speed-up of the CGP method
to increase dramatically for versions of the method that use other, suboptimal,
elliptic solvers, which are generally quadratic cost. It is also demonstrated
that numerical oscillations due to lower grid resolutions, in which the Munk
scales are not resolved adequately, are effectively eliminated with CGP method.


title:
Inner Disc Obscuration in GRS 1915+105 Based on Relativistic Slim Disc
  Model

abstract:
  We study the observational signatures of the relativistic slim disc of 10
M_sun black hole, in a wide range of mass accretion rate, mdot, dimensionless
spin parameter, a_ast, and viewing angle, i. In general, the innermost
temperature, T_in increases with the increase of i for a fixed value of mdot
and a_ast, due to the Doppler effect. However, for i > 50 and mdot > mdot_turn,
T_in starts to decrease with the increase of mdot. This is a result of
self-obscuration -- the radiation from the innermost hot part of the disc is
blocked by the surrounding cooler part. The value of mdot_turn and the
corresponding luminosities depend on a_ast and i. Such obscuration effects
cause an interesting behavior on the disc luminosity (L_disc) -- T_in plane for
high inclinations. In addition to the standard-disc branch which appears below
mdot_turn and which obeys L_disc propto T_in^4 -relation, another branch above
mdot_turn, which is nearly horizontal, may be observed at luminosities close to
the Eddington luminosity. We show that these features are likely observed in a
Galactic X-ray source, GRS 1915+105. We support a high spin parameter (a_ast >
0.9) for GRS 1915+105 since otherwise the high value of T_in and small size of
the emitting region (r_in < 1r_S) cannot be explained.


title: Connecting Transitions in Galaxy Properties to Refueling

abstract:
  We relate transitions in galaxy structure and gas content to refueling, here
defined to include both the external gas accretion and the internal gas
processing needed to renew reservoirs for star formation. We analyze two z=0
data sets: a high-quality ~200-galaxy sample (the Nearby Field Galaxy Survey,
data release herein) and a volume-limited ~3000-galaxy sample with reprocessed
archival data. Both reach down to baryonic masses ~10^9Msun and span
void-to-cluster environments. Two mass-dependent transitions are evident: (i)
below the "gas-richness threshold" scale (V~125km/s), gas-dominated
quasi-bulgeless Sd--Im galaxies become numerically dominant, while (ii) above
the "bimodality" scale (V~200km/s), gas-starved E/S0s become the norm.
Notwithstanding these transitions, galaxy mass (or V as its proxy) is a poor
predictor of gas-to-stellar mass ratio M_gas/M_*. Instead, M_gas/M_* correlates
well with the ratio of a galaxy's stellar mass formed in the last Gyr to its
preexisting stellar mass, such that the two ratios have numerically similar
values. This striking correspondence between past-averaged star formation and
current gas richness implies routine refueling of star-forming galaxies on Gyr
timescales. We argue that this refueling underlies the tight M_gas/M_* vs.
color correlations often used to measure "photometric gas fractions."
Furthermore, the threshold and bimodality scale transitions reflect
mass-dependent demographic shifts between three refueling regimes --- accretion
dominated, processing dominated, and quenched. In this picture, gas-dominated
dwarfs are explained not by inefficient star formation but by overwhelming gas
accretion, which fuels stellar mass doubling in <~1Gyr. Moreover, moderately
gas-rich bulged disks such as the Milky Way are transitional, becoming abundant
only in the narrow range between the threshold and bimodality scales.


title: Additive Combination Spaces

abstract:
  We introduce a class of metric spaces called $p$-additive combinations and
show that for such spaces we may deduce information about their $p$-negative
type behaviour by focusing on a relatively small collection of almost disjoint
metric subspaces, which we call the components. In particular we deduce a
formula for the $p$-negative type gap of the space in terms of the $p$-negative
type gaps of the components, independent of how the components are arranged in
the ambient space. This generalizes earlier work on metric trees by Doust and
Weston. The results hold for semi-metric spaces as well, as the triangle
inequality is not used.


title: A Secure and Comparable Text Encryption Algorithm

abstract:
  This paper discloses a simple algorithm for encrypting text messages, based
on the NP-completeness of the subset sum problem, such that the similarity
between encryptions is roughly proportional to the semantic similarity between
their generating messages. This allows parties to compare encrypted messages
for semantic overlap without trusting an intermediary and might be applied, for
example, as a means of finding scientific collaborators over the Internet.


title:
Experimental realization of a quantum phase transition of polaritonic
  excitations

abstract:
  We report an experimental realization of the Jaynes-Cummings-Hubbard (JCH)
model using the internal and radial phonon states of two trapped ions. An
adiabatic transfer corresponding to a quantum phase transition from a localized
insulator ground state to a delocalized superfluid (SF) ground state is
demonstrated. The SF phase of polaritonic excitations characteristic of the
interconnected Jaynes-Cummings (JC) system is experimentally explored, where a
polaritonic excitation refers to a combination of an atomic excitation and a
phonon interchanged via a JC coupling.


title:
No compelling evidence of significant early star cluster disruption in
  the Large Magellanic Cloud

abstract:
  Whether or not the rich star cluster population in the Large Magellanic Cloud
(LMC) is affected by significant disruption during the first few x 10^8 yr of
its evolution is an open question and the subject of significant current
debate. Here, we revisit the problem, adopting a homogeneous data set of
broad-band imaging observations. We base our analysis mainly on two sets of
self-consistently determined LMC cluster ages and masses, one using standard
modelling and one which takes into account the effects of stochasticity in the
clusters' stellar mass functions. On their own, the results based on any of the
three complementary analysis approaches applied here are merely indicative of
the physical conditions governing the cluster population. However, the
combination of our results from all three different diagnostics leaves little
room for any conclusion other than that the optically selected LMC star cluster
population exhibits no compelling evidence of significant disruption -- for
clusters with masses, M_cl, of log(M_cl/M_sun) >= 3.0-3.5 -- between the age
ranges of [3-10] Myr and [30-100] Myr, either "infant mortality" or otherwise.
In fact, there is no evidence of any destruction beyond that expected from
simple models just including stellar dynamics and stellar evolution for ages up
to 1 Gyr. It seems, therefore, that the difference in environmental conditions
in the Magellanic Clouds on the one hand and significantly more massive
galaxies on the other may be the key to understanding the apparent variations
in cluster disruption behaviour at early times.


title:
Estimating Clique Composition and Size Distributions from Sampled
  Network Data

abstract:
  Cliques are defined as complete graphs or subgraphs; they are the strongest
form of cohesive subgroup, and are of interest in both social science and
engineering contexts. In this paper we show how to efficiently estimate the
distribution of clique sizes from a probability sample of nodes obtained from a
graph (e.g., by independence or link-trace sampling). We introduce two types of
unbiased estimators, one of which exploits labeling of sampled nodes neighbors
and one of which does not require this information. We compare the estimators
on a variety of real-world graphs and provide suggestions for their use. We
generalize our estimators to cases in which cliques are distinguished not only
by size but also by node attributes, allowing us to estimate clique composition
by size. Finally, we apply our methodology to a sample of Facebook users to
estimate the clique size distribution by gender over the social graph.


title: Clark model in general situation

abstract:
  For a unitary operator the family of its unitary perturbations by rank one
operators with fixed range is parametrized by a complex parameter $\gamma,
|\gamma|=1$. Namely all such unitary perturbations are $U_\gamma:=U+(\gamma-1)
(., b_1)_{\mathcal H} b$, where $b\in\mathcal H, \|b\|=1, b_1=U^{-1} b,
|\gamma|=1$. For $|\gamma|<1$ operators $U_\gamma$ are contractions with
one-dimensional defects.
  Restricting our attention on the non-trivial part of perturbation we assume
that $b$ is cyclic for $U$. Then the operator $U_\gamma$, $|\gamma|<1$ is a
completely non-unitary contraction, and thus unitarily equivalent to its
functional model $\mathcal M_\gamma$, which is the compression of the
multiplication by the independent variable $z$ onto the model space $\mathcal
K_{\theta_\gamma}$, where $\theta_\gamma$ is the characteristic function of the
contraction $U_\gamma$.
  The Clark operator $\Phi_\gamma$ is a unitary operator intertwining
$U_\gamma, |\gamma|<1$ and its model $\mathcal M_\gamma$, $\mathcal M_\gamma
\Phi_\gamma = \Phi_\gamma U_\gamma$. If spectral measure of $U$ is purely
singular (equivalently, $\theta_\gamma$ is inner), operator $\Phi_\gamma$ was
described from a slightly different point of view by D. Clark. When
$\theta_\gamma$ is extreme point of the unit ball in $H^\infty$ was treated by
D. Sarason using the sub-Hardy spaces introduced by L. de Branges.
  We treat the general case and give a systematic presentation of the subject.
We find a formula for the adjoint operator $\Phi^*_\gamma$ which is represented
by a singular integral operator, generalizing the normalized Cauchy transform
studied by A. Poltoratskii. We present a "universal" representation that works
for any transcription of the functional model. We then give the formulas
adapted for the Sz.-Nagy--Foias and de Branges--Rovnyak transcriptions, and
finally obtain the representation of $\Phi_\gamma$.


title: Low Temperature Nanoscale Electronic Transport on the MoS_2 surface

abstract:
  Two-probe electronic transport measurements on a Molybdenum Disulphide
(MoS_2) surface were performed at low temperature (30K) under ultra-high vacuum
conditions. Two scanning tunneling microscope tips were precisely positioned in
tunneling contact to measure the surface current-voltage characteristics. The
separation between the tips is controllably varied and measured using a high
resolution scanning electron microscope. The MoS_2 surface shows a surface
electronic gap (E_S) of 1.4eV measured at a probe separation of 50nm.
Furthermore, the two- probe resistance measured outside the electronic gap
shows 2D-like behavior with the two-probe separation.


title: Active Noise Control with Sampled-Data Filtered-x Adaptive Algorithm

abstract:
  Analysis and design of filtered-x adaptive algorithms are conventionally done
by assuming that the transfer function in the secondary path is a discrete-time
system. However, in real systems such as active noise control, the secondary
path is a continuous-time system. Therefore, such a system should be analyzed
and designed as a hybrid system including discrete- and continuous- time
systems and AD/DA devices. In this article, we propose a hybrid design taking
account of continuous-time behavior of the secondary path via lifting
(continuous-time polyphase decomposition) technique in sampled-data control
theory.


title:
Undecidability of $L(\mathcal{A})=L(\mathcal{B})$ recognized by measure
  many 1-way quantum automata

abstract:
  Let $L_{>\lambda}(\mathcal{A})$ and $L_{\geq\lambda}(\mathcal{A})$ be the
languages recognized by {\em measure many 1-way quantum finite automata
(MMQFA)} (or,{\em enhanced 1-way quantum finite automata(EQFA)}) $\mathcal{A}$
with strict, resp. non-strict cut-point $\lambda$. We consider the languages
equivalence problem, showing that
  \begin{itemize}
  \item {both strict and non-strict languages equivalence are undecidable;}
  \item {to do this, we provide an additional proof of the undecidability of
non-strict and strict emptiness of MMQFA(EQFA), and then reducing the languages
equivalence problem to emptiness problem;}
  \item{Finally, some other Propositions derived from the above results are
collected.}
  \end{itemize}


title: YY Filter - A Paradigm of Digital Signal Processing

abstract:
  YY filter, named after the founder Prof. Yutaka Yamamoto, is a digital filter
designed by sampled-data control theory, which can optimize the analog
performance of the signal processing system with AD/DA converters. This article
discusses problems in conventional signal processing and introduces advantages
of the YY filter.


title:
Upper Bounds On the ML Decoding Error Probability of General Codes over
  AWGN Channels

abstract:
  In this paper, parameterized Gallager's first bounding technique (GFBT) is
presented by introducing nested Gallager regions, to derive upper bounds on the
ML decoding error probability of general codes over AWGN channels. The three
well-known bounds, namely, the sphere bound (SB) of Herzberg and Poltyrev, the
tangential bound (TB) of Berlekamp, and the tangential-sphere bound (TSB) of
Poltyrev, are generalized to general codes without the properties of
geometrical uniformity and equal energy. When applied to the binary linear
codes, the three generalized bounds are reduced to the conventional ones. The
new derivation also reveals that the SB of Herzberg and Poltyrev is equivalent
to the SB of Kasami et al., which was rarely cited in the literatures.


title: On the application of McDiarmid's inequality to complex systems

abstract:
  McDiarmid's inequality has recently been proposed as a tool for setting
margin requirements for complex systems. If $F$ is the bounded output of a
complex system, depending on a vector of $n$ bounded inputs, this inequality
provides a bound $B_F(\epsilon)$, such that the probability of a deviation
exceeding $B_F(\epsilon)$ is less than $\epsilon$. I compare this bound with
the absolute bound, based on the range of $F$. I show that when $n_{eff}$, the
effective number of independent variates, is small, and when $\epsilon$ is
small, the absolute bound is smaller than $B_F(\epsilon)$, while also providing
a smaller probability of exceeding the bound, i.e., zero instead of $\epsilon$.
Thus, for $B_F(\epsilon)$ to be useful, the number of inputs must be large,
with a small dependence on any single input, which is consistent with the usual
guidance for application of concentration-of-measure results. When the number
of inputs is small, or when a small number of inputs account for much of the
uncertainty, the absolute bounds will provide better results. The use of
absolute bounds is equivalent to the original formulation of the method of
Quantification of Margins and Uncertainties (QMU).


title:
Fabrication of nanopores in a graphene sheet with heavy ions: a
  molecular dynamics study

abstract:
  Molecular dynamics (MD) simulations were performed to study the formation
process of nanopores in a suspended graphene sheet irradiated by using
energetic ions though a mask. By controlling the ion parameters including mass,
energy and incident angle, different kinds of topography were observed in the
graphene sheet. Net-like defective strucutures with carbon atom chains can be
formed at low ion fluence, which provides the possibility to functionalize the
irradiated sample with subsequent chemical methods; finally a perfect nanopore
with smooth edge appears as the ion fluence is high enough. We found that the
dependence of ion damage efficiency on ion fluence, energy and incident angle
are different from that predicted by the semi-empirical model based on the
binary-collision approximation, which results from the special structure of
graphene. Our results demonstrate that it is feasible to fabricate controlled
nanopores/nanostructures in graphene via heavy ion irradiation.


title:
SUSY breaking by nonperturbative dynamics in a matrix model for 2D type
  IIA superstrings

abstract:
  We explicitly compute nonperturbative effects in a supersymmetric double-well
matrix model corresponding to two-dimensional type IIA superstring theory on a
nontrivial Ramond-Ramond background. We analytically determine the full
one-instanton contribution to the free energy and one-point function, including
all perturbative fluctuations around the one-instanton background. The leading
order two-instanton contribution is determined as well. We see that
supersymmetry is spontaneously broken by instantons, and that the breaking
persists after taking a double scaling limit which realizes the type IIA theory
from the matrix model. The result implies that spontaneous supersymmetry
breaking occurs by nonperturbative dynamics in the target space of the IIA
theory. Furthermore, we numerically determine the full nonperturbative effects
by recursive evaluation of orthogonal polynomials. The free energy of the
matrix model appears well-defined and finite even in the strongly coupled limit
of the corresponding type IIA theory. The result might suggest a weakly coupled
theory appearing as an S-dual to the two-dimensional type IIA superstring
theory.


title: Existence of Minimizers for Non-Level Convex Supremal Functionals

abstract:
  The paper is devoted to determine necessary and sufficient conditions for
existence of solutions to the problem ${\rm inf}{{\rm ess sup}_{x \in \Omega}
f(\nabla u(x)): u \in u_0 + W^{1,\infty}_0(\Omega)}$ when the supremand $f$ is
not necessarily level convex. These conditions are obtained through a
comparison with the related level convex problem and are written in terms of a
differential inclusion involving the boundary datum. Several conditions of
convexity for the supremand $f$ are also investigated.


title: Quasi-local characteristics of dynamical extreme black holes

abstract:
  Introducing the concept of the extreme trapping horizon, we discuss geometric
features of dynamical extreme black holes in four dimensions and then derive
the integral identities which hold for the dynamical extreme black holes. We
address the causal/geometrical features too.


title: Search-Space Characterization for Real-time Heuristic Search

abstract:
  Recent real-time heuristic search algorithms have demonstrated outstanding
performance in video-game pathfinding. However, their applications have been
thus far limited to that domain. We proceed with the aim of facilitating wider
applications of real-time search by fostering a greater understanding of the
performance of recent algorithms. We first introduce eight
algorithm-independent complexity measures for search spaces and correlate their
values with algorithm performance. The complexity measures are statistically
shown to be significant predictors of algorithm performance across a set of
commercial video-game maps. We then extend this analysis to a wider variety of
search spaces in the first application of database-driven real-time search to
domains outside of video-game pathfinding. In doing so, we gain insight into
algorithm performance and possible enhancement as well as into search space
complexity.


title:
On the Capacity and Degrees of Freedom Regions of MIMO Interference
  Channels with Limited Receiver Cooperation

abstract:
  This paper gives the approximate capacity region of a two-user MIMO
interference channel with limited receiver cooperation, where the gap between
the inner and outer bounds is in terms of the total number of receive antennas
at the two receivers and is independent of the actual channel values. The
approximate capacity region is then used to find the degrees of freedom region.
For the special case of symmetric interference channels, we also find the
amount of receiver cooperation in terms of the backhaul capacity beyond which
the degrees of freedom do not improve. Further, the generalized degrees of
freedom are found for MIMO interference channels with equal number of antennas
at all nodes. It is shown that the generalized degrees of freedom improve
gradually from a "W" curve to a "V" curve with increase in cooperation in terms
of the backhaul capacity.


abstract:
  Models of the magnetic field enhancement at pits are discussed. In order to
build a model of pit, parameters that characterize a geometry of edges of pit,
such as a curvature radius and a slope angle of edge, should be included,
because the magnetic field is enhanced at an edge of a pit. A shape of the
bottom of the pit is not important, because the magnetic field attenuates at
the bottom. The simplest model of the pit is given by the two-dimensional pit
with a triangular section. The well-like pit, which is known to many
researchers, is a special case of this model. In this paper, idea and methods
to analytically evaluate the magnetic field enhancement factor of such models
are mentioned in detail. The well-like pit is considered as an instructive
exercise, where the famous results by Shemelin and Padamsee are reproduced
analytically. The triangular pit model, which is practically important for
studies of the quench of SRF cavity, are discussed in detail. Comparisons
between the prediction of the triangular-pit model and the vertical test
results are also shown.


title:
Designing secure clustering protocol with the approach of reducing
  energy consumption in wireless sensor networks

abstract:
  In recent years, many researchers have focused on wireless sensor networks
and their applications. To obtain scalability potential in these networks most
of the nodes are categorized as distinct groups named cluster and the node
which is selected as cluster head or Aggregation Node offers the operation of
data collection from other cluster nodes and aggregation and sending it to the
rest of the network. Clustering and data aggregation increase network
scalability and cause that limited resources of the network are used well.
However, these mechanisms also make several breaches in the network, for
example in clustered networks cluster head nodes are considered Desirable and
attractive targets for attackers since reaching their information whether by
physical attack and node capturing or by other attacks, the attacker can obtain
the whole information of corresponding cluster. In this study secure clustering
of the nodes are considered with the approach of reducing energy consumption of
nodes and a protocol is presented that in addition to satisfying Advanced
security needs of wireless sensor networks reduces the amount of energy
consumption by the nodes. Due to network clustering there is scalability
potential in such a network and According to frequent change of cluster head
nodes load distribution is performed in the cluster and eventually increase the
network lifetime.


title:
Periodic approximations of the ergodic constants in the stochastic
  homogenization of nonlinear second-order (degenerate) equations

abstract:
  We prove that the effective nonlinearities (ergodic constants) obtained in
the stochastic homogenization of Hamilton-Jacobi, "viscous" Hamilton-Jacobi and
nonlinear uniformly elliptic pde are approximated by the analogous quantities
of appropriate "periodizations" of the equations. We also obtain an error
estimate, when there is a rate of convergence for the stochastic
homogenization.


title: The algorithm of noisy k-means

abstract:
  In this note, we introduce a new algorithm to deal with finite dimensional
clustering with errors in variables. The design of this algorithm is based on
recent theoretical advances (see Loustau (2013a,b)) in statistical learning
with errors in variables. As the previous mentioned papers, the algorithm mixes
different tools from the inverse problem literature and the machine learning
community. Coarsely, it is based on a two-step procedure: (1) a deconvolution
step to deal with noisy inputs and (2) Newton's iterations as the popular
k-means.


title:
Some exact values of the Harborth constant and its plus-minus weighted
  analogue

abstract:
  The Harborth constant of a finite abelian group is the smallest integer
$\ell$ such that each subset of $G$ of cardinality $\ell$ has a subset of
cardinality equal to the exponent of the group whose elements sum to the
neutral element of the group. The plus-minus weighted analogue of this constant
is defined in the same way except that instead of considering the sum of all
elements of the subset one can choose to add either the element or its inverse.
We determine these constants for certain groups, mainly groups that are the
direct sum of a cyclic group and a group of order 2. Moreover, we contrast
these results with existing results and conjectures on these problems.


title: Remarks on the plus-minus weighted Davenport constant

abstract:
  For $(G,+)$ a finite abelian group the plus-minus weighted Davenport
constant, denoted $\mathsf{D}_{\pm}(G)$, is the smallest $\ell$ such that each
sequence $g_1 ... g_{\ell}$ over $G$ has a weighted zero-subsum with weights +1
and -1, i.e., there is a non-empty subset $I \subset \{1,..., \ell\}$ such that
$\sum_{i \in I} a_i g_i =0$ for $a_i \in \{+1,-1\}$. We present new bounds for
this constant, mainly lower bounds, and also obtain the exact value of this
constant for various additional types of groups.


title: Orbits in a stochastic Goodwin-Lotka-Volterra model

abstract:
  This paper examines the cycling behavior of a deterministic and a stochastic
version of the economic interpretation of the Lotka-Volterra model, the Goodwin
model. We provide a characterization of orbits in the deterministic highly
non-linear model. We then study the cycling behavior for a stochastic version,
where a Brownian noise is introduced via an heterogeneous productivity factor.
Sufficient conditions for existence of the system are provided. We prove that
the system produces cycles around an equilibrium point in finite time for
general volatility levels, using stochastic Lyapunov techniques for recurent
domains. Numerical insights are provided.


title: Entanglement and tensor network states

abstract:
  These lecture notes provide a brief overview of methods of entanglement
theory applied to the study of quantum many-body systems, as well as of tensor
network states capturing quantum states naturally appearing in condensed-matter
systems.


title: Affecting Non-Markovian behaviour by changing bath structures

abstract:
  For many open quantum systems, a master equation approach employing the
Markov approximation cannot reliably describe the dynamical behaviour. This is
the case, for example, in a number of solid state or biological systems, and it
has motivated a line of research aimed at quantifying the amount of
non-Markovian behaviour in a given model. Within this framework, we investigate
the dynamics of a quantum harmonic oscillator linearly coupled to a bosonic
bath. We focus on Gaussian states, which are suitably treated using a
covariance matrix approach. Concentrating on an entanglement based
non-Markovian behaviour quantifier (NMBQ) proposed by Rivas et. al. [1], we
consider the role that near resonant and off-resonant modes play in affecting
the NMBQ. By using a large but finite bath of oscillators for both Ohmic and
super Ohmic spectral densities we find, by systematically increasing the
coupling strength, initially the near resonant modes provide the most
significant non-Markovian effects, while after a certain threshold of coupling
strength the off-resonant modes play the dominant role. We also consider the
NMBQ for two other models where we add a single strongly coupled oscillator to
the model in extra bath mode and 'buffer' configurations, which affects the
modes that determine non-Markovian behaviour.


title:
Improving the Testability of Object-oriented Software during Testing and
  Debugging Processes

abstract:
  Testability is the probability whether tests will detect a fault, given that
a fault in the program exists. How efficiently the faults will be uncovered
depends upon the testability of the software. Various researchers have proposed
qualitative and quantitative techniques to improve and measure the testability
of software. In literature, a plethora of reliability growth models have been
used to assess and measure the quantitative quality assessment of software
during testing and operational phase. The knowledge about failure distribution
and their complexity can improve the testability of software. Testing effort
allocation can be made easy by knowing the failure distribution and complexity
of faults, and this will ease the process of revealing faults from the
software. As a result, the testability of the software will be improved. The
parameters of the model along with the proportion of faults of different
complexity to be removed from the software have been presented in the paper .We
have used failure data of two object oriented software developed under open
source environment namely MySQL for python and Squirrel SQL Client for
estimation purpose


title: Reheating dynamics affects non-perturbative decay of spectator fields

abstract:
  The behaviour of oscillating scalar spectator fields after inflation depends
on the thermal background produced by inflaton decay. Resonant decay of the
spectator is often blocked by large induced thermal masses. We account for the
finite decay width of the inflaton and the protracted build-up of the thermal
bath to determine the early evolution of a homogeneous spectator field, \sigma,
coupled to the Higgs Boson, \Phi, through the term g^2 \sigma^2 \Phi^2, the
only renormalisable coupling of a new scalar to the Standard Model. We find
that for very large higgs-spectator coupling g > 10^{-3}, the resonance is not
always blocked as was previously suggested. As a consequence, the oscillating
spectator can decay quickly. For other parameter values, we find that although
qualitative features of the thermal blocking still hold, the dynamics are
altered compared to the instant decay case. These findings are important for
curvaton models, where the oscillating field must be relatively long lived in
order to produce the curvature perturbation. They are also relevant for other
spectator fields, which must decay sufficiently early to avoid spoiling the
predictions of baryogenesis and nucleosynthesis.


title: Some remarks on relations between the $\mu$-parameters of regular graphs

abstract:
  For an undirected, simple, finite, connected graph $G$, we denote by $V(G)$
and $E(G)$ the sets of its vertices and edges, respectively. A function
$\varphi:E(G)\rightarrow \{1,...,t\}$ is called a proper edge $t$-coloring of a
graph $G$, if adjacent edges are colored differently and each of $t$ colors is
used. The least value of $t$ for which there exists a proper edge $t$-coloring
of a graph $G$ is denoted by $\chi'(G)$. For any graph $G$, and for any integer
$t$ satisfying the inequality $\chi'(G)\leq t\leq |E(G)|$, we denote by
$\alpha(G,t)$ the set of all proper edge $t$-colorings of $G$. Let us also
define a set $\alpha(G)$ of all proper edge colorings of a graph $G$: $$
\alpha(G)\equiv\bigcup_{t=\chi'(G)}^{|E(G)|}\alpha(G,t). $$
  An arbitrary nonempty finite subset of consecutive integers is called an
interval. If $\varphi\in\alpha(G)$ and $x\in V(G)$, then the set of colors of
edges of $G$ which are incident with $x$ is denoted by $S_G(x,\varphi)$ and is
called a spectrum of the vertex $x$ of the graph $G$ at the proper edge
coloring $\varphi$. If $G$ is a graph and $\varphi\in\alpha(G)$, then define
$f_G(\varphi)\equiv|\{x\in V(G)/S_G(x,\varphi) \textrm{is an interval}\}|$.
  For a graph $G$ and any integer $t$, satisfying the inequality $\chi'(G)\leq
t\leq |E(G)|$, we define: $$
\mu_1(G,t)\equiv\min_{\varphi\in\alpha(G,t)}f_G(\varphi),\qquad
\mu_2(G,t)\equiv\max_{\varphi\in\alpha(G,t)}f_G(\varphi). $$
  For any graph $G$, we set: $$ \mu_{11}(G)\equiv\min_{\chi'(G)\leq
t\leq|E(G)|}\mu_1(G,t),\qquad \mu_{12}(G)\equiv\max_{\chi'(G)\leq
t\leq|E(G)|}\mu_1(G,t), $$ $$ \mu_{21}(G)\equiv\min_{\chi'(G)\leq
t\leq|E(G)|}\mu_2(G,t),\qquad \mu_{22}(G)\equiv\max_{\chi'(G)\leq
t\leq|E(G)|}\mu_2(G,t). $$
  For regular graphs, some relations between the $\mu$-parameters are obtained.


title: E-Governance: Past, Present and Future in India

abstract:
  Due to widespread demand of E-governance and exponentially increasing size of
data, new technologies like Open source solutions and cloud computing need to
be incorporated. In this paper, the latest trends of technology that the
government of most of the country has adopted have been discussed. While
working on this project we have concluded that E-Governance has made the
working of government more efficient and more transparent to its citizens We
have also presented an exhaustive list of E-Governance projects which is
currently being used in India and in international scenario. We have provided a
mechanism for improving E-Governance by including technologies such as Open
Source and Cloud Computing.


title: History Based Coalition Formation in Hedonic Context Using Trust

abstract:
  In this paper we address the problem of coalition formation in hedonic
context. Our modelling tries to be as realistic as possible. In previous
models, once an agent joins a coalition it would not be able to leave the
coalition and join the new one; in this research we made it possible to leave a
coalition but put some restrictions to control the behavior of agents. Leaving
or staying of an agent in a coalition will affect on the trust of the other
agents included in this coalition. Agents will use the trust values in
computing the expected utility of coalitions. Three different risk behaviors
are introduced for agents that want to initiate a coalition. Using these risk
behaviors, some simulations are made and results are analyzed.


title: Lectures on Minimal Surface Theory

abstract:
  An article based on a four-lecture introductory minicourse on minimal surface
theory given at the 2013 summer program of the Institute for Advanced Study and
the Park City Mathematics Institute.


title: Sorted Range Reporting Revisited

abstract:
  We consider the two-dimensional sorted range reporting problem. Our data
structure requires O(n lglg n) words of space and O(lglg n + k lglg n) query
time, where k is the number of points in the query range. This data structure
improves a recent result of Nekrich and Navarro [8] by a factor of O(lglg n) in
query time, and matches the state of the art for unsorted range reporting [1].


title: Shape-induced anisotropy in antiferromagnetic nanoparticles

abstract:
  High fraction of the surface atoms considerably enhances the influence of
size and shape on the magnetic and electronic properties of nanoparticles.
Shape effects in ferromagnetic nanoparticles are well understood and allow to
set and control the parameters of a sample that affect its magnetic anisotropy
during production. In the present paper we study the shape effects in the other
widely used magnetic materials -- antiferromagnets, -- which possess
vanishingly small or zero macroscopic magnetization. We take into account the
difference between the surface and bulk magnetic anisotropy of a nanoparticle
and show that the effective magnetic anisotropy depends on the particle shape
and crystallographic orientation of its faces. Corresponding shape-induced
contribution to the magnetic anisotropy energy is proportional to the particle
volume, depends on magnetostriction, and can cause formation of equilibrium
domain structure. Crystallographic orientation of the nanoparticle surface
determines the type of domain structure. The proposed model allows to predict
the magnetic properties of antiferromagnetic nanoparticles depending on their
shape and treatment.


title:
Exploring the QCD phase diagram through high energy nuclear collisions:
  An overview

abstract:
  We present an overview of the status of the studies related to the phase
diagram of strong interactions through high-energy nuclear collisions. We
discuss both the theoretical and experimental status of establishing the
various QCD phase structures in the phase diagram, such as, quark-gluon phase,
quark-hadron crossover, crossover temperature, phase boundary and critical
point.


title: On Linear Congestion Games with Altruistic Social Context

abstract:
  We study the issues of existence and inefficiency of pure Nash equilibria in
linear congestion games with altruistic social context, in the spirit of the
model recently proposed by de Keijzer {\em et al.} \cite{DSAB13}. In such a
framework, given a real matrix $\Gamma=(\gamma_{ij})$ specifying a particular
social context, each player $i$ aims at optimizing a linear combination of the
payoffs of all the players in the game, where, for each player $j$, the
multiplicative coefficient is given by the value $\gamma_{ij}$. We give a broad
characterization of the social contexts for which pure Nash equilibria are
always guaranteed to exist and provide tight or almost tight bounds on their
prices of anarchy and stability. In some of the considered cases, our
achievements either improve or extend results previously known in the
literature.


title: Curvature and geometric modules of noncommutative spheres and tori

abstract:
  When considered as submanifolds of Euclidean space, the Riemannian geometry
of the round sphere and the Clifford torus may be formulated in terms of
Poisson algebraic expressions involving the embedding coordinates, and a
central object is the projection operator, projecting tangent vectors in the
ambient space onto the tangent space of the submanifold. In this note, we point
out that there exist noncommutative analogues of these projection operators,
which implies a very natural definition of noncommutative tangent spaces as
particular projective modules. These modules carry an induced connection from
Euclidean space, and we compute its scalar curvature.


title: Measuring risk with multiple eligible assets

abstract:
  The risk of financial positions is measured by the minimum amount of capital
to raise and invest in eligible portfolios of traded assets in order to meet a
prescribed acceptability constraint. We investigate nondegeneracy, finiteness
and continuity properties of these risk measures with respect to multiple
eligible assets. Our finiteness and continuity results highlight the interplay
between the acceptance set and the class of eligible portfolios. We present a
simple, alternative approach to the dual representation of convex risk measures
by directly applying to the acceptance set the external characterization of
closed, convex sets. We prove that risk measures are nondegenerate if and only
if the pricing functional admits a positive extension which is a supporting
functional for the underlying acceptance set, and provide a characterization of
when such extensions exist. Finally, we discuss applications to set-valued risk
measures, superhedging with shortfall risk, and optimal risk sharing.


title:
A decomposition theorem for positive maps, and the projection onto a
  spin factor

abstract:
  It is shown that each positive map between matrix algebras is the sum of a
maximal decomposable map and an atomic map which is both optimal and
co-optimal. The result is analyzed in detail for the positive projection onto a
spin factor.


title: A high-order electromagnetic gyrokinetic model

abstract:
  A high-order extension is presented for the electromagnetic gyrokinetic
formulation in which the parallel canonical momentum is taken as one of phase
space coordinates. The high-order displacement vector associated with the
guiding-center transformation should be considered in the long wavelength
regime. This yields addtional terms in the gyrokinetic Hamiltonian which lead
to modifications to the gyrokinetic Poisson and Amp\`ere equations. In
addition, the high-order piece of the guiding-center transformation for the
parallel canonical momentum should be also kept in the electromagnetic model.
The high-order piece contains the Ba\~nos drift effect and further modifies the
gyrokinetic Amp\`ere equation.


title:
A numerical study of the window condition for Chern numbers of
  Hofstadter Butterflies

abstract:
  The Chern numbers for Hofstadter models with rational flux 2*pi*p/q are
partially determined by a Diophantine equation. A Mod q ambiguity remains. The
resolution of this ambiguity is only known for the rectangular lattice with
nearest neighbors hopping where it has the form of a "window condition". We
study a Hofstadter butterfly on the triangular lattice for which the resolution
of ambiguity is open. In the model many pairs (p,q) satisfy a window condition
which is shifted relative to the window of the square model. However, we also
find pairs (p,q) where the Chern numbers do not belong to any contiguous
window. This shows that the rectangular model and the one we study on the
triangular lattice are not adiabatically connected: Many gaps must close. Our
results suggest the conjecture that the mod q ambiguity in the Diophantine
equation generically reduces to a sign ambiguity.


title:
A Stable Parametric Finite Element Discretization of Two-Phase
  Navier--Stokes Flow

abstract:
  We present a parametric finite element approximation of two-phase flow. This
free boundary problem is given by the Navier--Stokes equations in the two
phases, which are coupled via jump conditions across the interface. Using a
novel variational formulation for the interface evolution gives rise to a
natural discretization of the mean curvature of the interface. The parametric
finite element approximation of the evolving interface is then coupled to a
standard finite element approximation of the two-phase Navier--Stokes equations
in the bulk. Here enriching the pressure approximation space with the help of
an XFEM function ensures good volume conservation properties for the two phase
regions. In addition, the mesh quality of the parametric approximation of the
interface in general does not deteriorate over time, and an equidistribution
property can be shown for a semidiscrete continuous-in-time variant of our
scheme in two space dimensions. Moreover, our finite element approximation can
be shown to be unconditionally stable. We demonstrate the applicability of our
method with some numerical results in two and three space dimensions.


title:
The Power of Dynamic Distance Oracles: Efficient Dynamic Algorithms for
  the Steiner Tree

abstract:
  In this paper we study the Steiner tree problem over a dynamic set of
terminals. We consider the model where we are given an $n$-vertex graph
$G=(V,E,w)$ with positive real edge weights, and our goal is to maintain a tree
which is a good approximation of the minimum Steiner tree spanning a terminal
set $S \subseteq V$, which changes over time. The changes applied to the
terminal set are either terminal additions (incremental scenario), terminal
removals (decremental scenario), or both (fully dynamic scenario). Our task
here is twofold. We want to support updates in sublinear $o(n)$ time, and keep
the approximation factor of the algorithm as small as possible. We show that we
can maintain a $(6+\varepsilon)$-approximate Steiner tree of a general graph in
$\tilde{O}(\sqrt{n} \log D)$ time per terminal addition or removal. Here, $D$
denotes the stretch of the metric induced by $G$. For planar graphs we achieve
the same running time and the approximation ratio of $(2+\varepsilon)$.
Moreover, we show faster algorithms for incremental and decremental scenarios.
Finally, we show that if we allow higher approximation ratio, even more
efficient algorithms are possible. In particular we show a polylogarithmic time
$(4+\varepsilon)$-approximate algorithm for planar graphs.
  One of the main building blocks of our algorithms are dynamic distance
oracles for vertex-labeled graphs, which are of independent interest. We also
improve and use the online algorithms for the Steiner tree problem.


title: Information-Based Physics and the Influence Network

abstract:
  This essay considers a simple model of observers that are influenced by the
world around them. Consistent quantification of information about such
influences results in a great deal of familiar physics. The end result is a new
perspective on relativistic quantum mechanics, which includes both a way of
conceiving of spacetime as well as particle "properties" that may be amenable
to a unification of quantum mechanics and gravity. Rather than thinking about
the universe as a computer, perhaps it is more accurate to think about it as a
network of influences where the laws of physics derive from both consistent
descriptions and optimal information-based inferences made by embedded
observers.


title: Measurements of the top-quark properties at CMS

abstract:
  Measurements of several top-quark properties, obtained from the CMS data
collected in 2011 and 2012 at centre-of-mass energies of 7 and 8 TeV are
presented. The results include measurements of the top pair charge asymmetry,
the W helicity in top quark decays and the search for anomalous couplings, the
top quark charge, and of the ttbar spin correlation. The fraction of top quarks
decaying into a W-boson and a b-quark relative to all top quark decays,
R=Br(t->Wb)/Br(t->Wq), as well as, the cross sections of ttbar events produced
in association with a photon or a W or a Z boson are also presented.


title:
Fast Multipole Preconditioners for Sparse Matrices Arising from Elliptic
  Equations

abstract:
  Among optimal hierarchical algorithms for the computational solution of
elliptic problems, the Fast Multipole Method (FMM) stands out for its
adaptability to emerging architectures, having high arithmetic intensity,
tunable accuracy, and relaxable global synchronization requirements. We
demonstrate that, beyond its traditional use as a solver in problems for which
explicit free-space kernel representations are available, the FMM has
applicability as a preconditioner in finite domain elliptic boundary value
problems, by equipping it with boundary integral capability for satisfying
conditions at finite boundaries and by wrapping it in a Krylov method for
extensibility to more general operators. Here, we do not discuss the well
developed applications of FMM to implement matrix-vector multiplications within
Krylov solvers of boundary element methods. Instead, we propose using FMM for
the volume-to-volume contribution of inhomogeneous Poisson-like problems, where
the boundary integral is a small part of the overall computation. Our method
may be used to precondition sparse matrices arising from finite
difference/element discretizations, and can handle a broader range of
scientific applications. Compared with multigrid methods, it is capable of
comparable algebraic convergence rates down to the truncation error of the
discretized PDE, and it offers potentially superior multicore and distributed
memory scalability properties on commodity architecture supercomputers.
Compared with other methods exploiting the low rank character of off-diagonal
blocks of the dense resolvent operator, FMM-preconditioned Krylov iteration may
reduce the amount of communication because it is matrix-free and exploits the
tree structure of FMM. We describe our tests in reproducible detail with freely
available codes and outline directions for further extensibility.


title: Overlapping modularity at the critical point of k-clique percolation

abstract:
  One of the most remarkable social phenomena is the formation of communities
in social networks corresponding to families, friendship circles, work teams,
etc. Since people usually belong to several different communities at the same
time, the induced overlaps result in an extremely complicated web of the
communities themselves. Thus, uncovering the intricate community structure of
social networks is a non-trivial task with great potential for practical
applications, gaining a notable interest in the recent years. The Clique
Percolation Method (CPM) is one of the earliest overlapping community finding
methods, which was already used in the analysis of several different social
networks. In this approach the communities correspond to k-clique percolation
clusters, and the general heuristic for setting the parameters of the method is
to tune the system just below the critical point of k-clique percolation.
However, this rule is based on simple physical principles and its validity was
never subject to quantitative analysis. Here we examine the quality of the
partitioning in the vicinity of the critical point using recently introduced
overlapping modularity measures. According to our results on real social- and
other networks, the overlapping modularities show a maximum close to the
critical point, justifying the original criteria for the optimal parameter
settings.


title:
Spin-Wave Propagation in the Presence of Interfacial
  Dzyaloshinskii-Moriya Interaction

abstract:
  In ferromagnetic thin films, broken inversion symmetry and spin-orbit
coupling give rise to interfacial Dzyaloshinskii-Moriya interactions. Analytic
expressions for spin-wave properties show that the interfacial
Dzyaloshinskii-Moriya interaction leads to non-reciprocal spin-wave
propagation, i.e. different properties for spin waves propagating in opposite
directions. In favorable situations, it can increase the spin-wave attenuation
length. Comparing measured spin wave properties in ferromagnet$|$normal metal
bilayers and other artificial layered structures with these calculations can
provide a useful characterization of the interfacial Dzyaloshinskii-Moriya
interactions.


title:
Obtaining high degree of circular polarization at X-ray FELs via a
  reverse undulator taper

abstract:
  Baseline design of a typical X-ray FEL undulator assumes a planar
configuration which results in a linear polarization of the FEL radiation.
However, many experiments at X-ray FEL user facilities would profit from using
a circularly polarized radiation. As a cheap upgrade one can consider an
installation of a short helical (or cross-planar) afterburner, but then one
should have an efficient method to suppress powerful linearly polarized
background from the main undulator. In this paper we propose a new method for
such a suppression: an application of the reverse taper in the main undulator.
We discover that in a certain range of the taper strength, the density
modulation (bunching) at saturation is practically the same as in the case of
non-tapered undulator while the power of linearly polarized radiation is
suppressed by orders of magnitude. Then strongly modulated electron beam
radiates at full power in the afterburner. Considering SASE3 undulator of the
European XFEL as a practical example, we demonstrate that soft X-ray radiation
pulses with peak power in excess of 100 GW and an ultimately high degree of
circular polarization can be produced. The proposed method is rather universal,
i.e. it can be used at SASE FELs and seeded (self-seeded) FELs, with any
wavelength of interest, in a wide range of electron beam parameters, and with
any repetition rate. It can be used at different X-ray FEL facilities, in
particular at LCLS after installation of the helical afterburner in the near
future.


title: Putting the Diffuse Interstellar Bands on the map - literally!

abstract:
  In a quest to further our understanding of the diffuse interstellar medium
(ISM) as well as the unidentified carriers of the diffuse interstellar bands
(DIBs), we are mapping DIBs across the sky using hundreds of hot stars as
background torches - globular clusters (in particular omega Centauri), nearby
stars in and around the Local Bubble, and stars within the Magellanic Clouds. I
describe the results so far obtained and our current experiments.


title:
How Channel Segregates Originates: The Flow of Accumulated Impurity
  Clusters in Solidifying Steels

abstract:
  The phenomenon, channel segregates (CS) as a result of gravity-driven flow
due to density contrast occurred in the solid-liquid mushy zones1during
solidification, often causes the severe destruction of homogeneity and even
some fatal damages. Investigation on its mechanism sheds light on the
understanding and controlling of the formation of solidifying metals,earth's
core, igneous rock and sea ice. Until now, it still remains controversial what
composes the density contrasts and, to what extent, how it affects channel
segregates. Here, we show that in experimental 500kg and 100 ton commercial
cast steel ingots CS originates from oxide Al2O3/MnS impurity clusters (OICs)
initially nucleated from the oxide (Al2O3) particles, which induce an extra
flow due to sharp density contrast between clusters and melt. The results
uncover that, as OICs enrich and grow, their driven flow becomes stronger than
the traditionally recognized inter-dendritic thermo-solutal convection,
dominating the subsequent opening of the channels. This study extends the
classical macrosegregation theory, highlights a significant technological
breakthrough to control CS, and could quickly yield practical benefits to the
worldwide manufacture of over 50 million tons of ingots, super-thick slab and
heavy castings annually, as well as has general implications for the
elaboration of other related natural phenomena.


title:
Electron Photoemission in Plasmonic Nanoparticle Arrays: Analysis of
  Collective Resonances and Embedding Effects

abstract:
  We theoretically study the characteristics of photoelectron emission in
plasmonic nanoparticle arrays. Nanoparticles are partially embedded in a
semiconductor, forming Schottky barriers at metal/semiconductor interfaces
through which photoelectrons can tunnel from the nanoparticle into the
semiconductor; photodetection in the infrared range, where photon energies are
below the semiconductor band gap (insufficient for band-to-band absorption in
semiconductor), is therefore possible. The nanoparticles are arranged in a
sparse rectangular lattice so that the wavelength of the lattice-induced
Rayleigh anomalies can overlap the wavelength of the localized surface plasmon
resonance of the individual particles, bringing about collective effects from
the nanoparticle array. Using full-wave numerical simulations, we analyze the
effects of lattice constant, embedding depth, and refractive index step between
the semiconductor layer and an adjacent transparent conductive oxide layer. We
show that the presence of refractive index mismatch between media surrounding
the nanoparticles disrupts the formation of a narrow absorption peak associated
with the Rayleigh anomaly, so the role of collective lattice effects in the
formation of plasmonic resonance is diminished. We also show that 5 to 20-times
increase of photoemission can be achieved on embedding of nanoparticles without
taking into account dynamics of ballistic electrons. The results obtained can
be used to increase efficiency of plasmon-based photodetectors and photovoltaic
devices. The results may provide clues to designing an experiment where the
contributions of surface and volume photoelectric effects to the overall
photocurrent would be defined.


title:
Probing the Sun's inner core using solar neutrinos: a new diagnostic
  method

abstract:
  The electronic density in the Sun's inner core is inferred from the 8B, 7Be
and pep neutrino flux measurements of the Super-Kamiokande, SNO and Borexino
experiments. We have developed a new method in which we use the KamLAND
detector determinations of the neutrino fundamental oscillation parameters: the
mass difference and the vacuum oscillation angle. Our results suggest that the
solar electronic density in the Sun's inner core (for a radius smaller than 10%
of the solar radius) is well above the current prediction of the standard solar
model, and by as much as 25%. A potential confirmation of these preliminary
findings can be achieved when neutrino detectors are able to reduce the error
of the electron-neutrino survival probability by a factor of 15.


title:
Phase-encoded measurement device independent quantum key distribution
  with practical spontaneous parametric-down-conversion sources

abstract:
  Measurement-device-independent quantum key distribution (MDI-QKD) with weak
coherent sources has been widely and meticulously analyzed. However, the
analysis for MDI-QKD with spontaneous parametric-down-conversion sources
(SPDCS) is incomplete. In this paper, by accounting for practical parameters of
SPDCS with thermal distribution, we presents an investigation on the
performances of MDI-QKD under the active three-intensity decoy protocol and the
passive one-intensity decoy protocol respectively. Phase randomization,
inherently prerequisite for decoy protocol, is taken into consideration for
evaluating the overall quantum bit gain and quantum bit error rate. The
numerical simulations show that MDI-QKD using SPDCS with practical decoy
protocols can be demonstrated comparable to the asymptotical case with infinite
decoy states and has apparent superiority both in transmission distance and key
generation rate compared to the MDI-QKD using weak coherent sources. Our
results also indicate that MDI-QKD using thermal distributed SPDCS with active
three-intensity decoy protocol performs better than the one with passive
one-intensity decoy protocol.


title: Magnetic fields from inflation: The CMB temperature anisotropies

abstract:
  The cosmic microwave background (CMB) temperature anisotropies from
primordial magnetic fields are studied. In addition to the known passive and
the compensated mode we discuss an inflationary magnetic mode in the curvature
perturbation, present when magnetic fields are generated during inflation. This
mode is absent if the generation mechanism is causal, e.g. a phase transition.
We compute and discuss the effect of this mode on the observed CMB anisotropy
spectrum, in comparison with the passive and compensated ones. We find that it
dominates the CMB anisotropy, and consequently leads to stronger constraints on
the amplitude $B_{1\,{\rm Mpc}}$ and spectral index $n_B$ of the magnetic field
than what usually found in CMB analyses from the compensated mode. This happens
in particular for spectral indexes $n_B>-3$: the inflationary magnetic mode is
always scale invariant, therefore through this mode even a magnetic field with
a spectrum which is not scale invariant can leave a detectable signal in the
CMB at large scales.


title: High Ecliptic Latitude Survey for Small Main-Belt Asteroids

abstract:
  Main-belt asteroids have been continuously colliding with one another since
they were formed. Its size distribution is primarily determined by the size
dependence of asteroid strength against catastrophic impacts. The strength
scaling law as a function of body size could depend on collision velocity, but
the relationship remains unknown especially under hypervelocity collisions
comparable to 10 km/sec. We present a wide-field imaging survey at ecliptic
latitude of around 25 deg for investigating the size distribution of small
main-belt asteroids which have highly inclined orbits. The analysis technique
allowing for efficient asteroid detections and high-accuracy photometric
measurements provide sufficient sample data to estimate the size distribution
of sub-km asteroids with inclinations larger than 14 deg. The best-fit
power-law slopes of the cumulative size distribution is 1.25 +/- 0.03 in the
diameter range of 0.6-1.0 km and 1.84 +/- 0.27 in 1.0-3.0 km. We provide a
simple size distribution model that takes into consideration the oscillations
of the power-law slope due to the transition from the gravity-scaled regime to
the strength-scaled regime. We find that the high-inclination population has a
shallow slope of the primary components of the size distribution compared to
the low-inclination populations. The asteroid population exposed to
hypervelocity impacts undergoes collisional processes that large bodies have a
higher disruptive strength and longer life-span relative to tiny bodies than
the ecliptic asteroids.


title:
Exploring the capabilities of the Anti-Coincidence Shield of the
  INTEGRAL spectrometer to study solar flares

abstract:
  INTEGRAL is a hard X-ray/gamma-ray observatory for astrophysics (ESA)
covering photon energies from 15 keV to 10 MeV. It was launched in 2002 and
since then the BGO detectors of the Anti-Coincidence shield (ACS) of the SPI
spectrometer have detected many hard X-ray (HXR) bursts from the Sun, producing
lightcurves at photon energies above ~ 100 keV. The spacecraft has a highly
elliptical orbit, providing a long uninterrupted observing time (about 90% of
the orbital period) with nearly constant background due to the reduction of the
crossing time of the Earth's radiation belts. However, due to technical
constraints, INTEGRAL cannot point to the Sun and high-energy solar photons are
always detected in non-standard observation conditions. To make the data useful
for solar studies, we have undertaken a major effort to specify the observing
conditions through Monte-Carlo simulations of the response of ACS for several
selected flares. We check the performance of the model employed for the
Monte-Carlo simulations using RHESSI observations for the same sample of solar
flares. We conclude that, despite the fact that INTEGRAL was not designed to
perform solar observations, ACS is a useful instrument in solar flare research.
In particular, its relatively large effective area allows the determination of
good-quality HXR/gamma-ray lightcurves for X- and M-class solar flares and, in
some cases, probably also for C-class flares.


title:
Neighbour-dependent point shifts and random exchange models: invariance
  and attractors

abstract:
  Consider a stationary renewal point process on the real line and divide each
of the segments it defines in a proportion given by \iid realisations of a
fixed distribution $G$ supported by [0,1]. We ask ourselves for which
interpoint distribution $F$ and which division distributions $G$, the division
points is again a renewal process with the same $F$? An evident case is that of
degenerate $F$ and $G$. Interestingly, the only other possibility is when $F$
is Gamma and $G$ is Beta with related parameters. In particular, the division
points of a Poisson process is again Poisson, if the division distribution is
Beta: B$(r,1-r)$ for some $0<r<1$. We show a similar behaviour of random
exchange models when a countable number of `agents' exchange randomly
distributed parts of their `masses' with neighbours. More generally, a
Dirichlet distribution arises in these models as a fixed point distribution
preserving independence of the masses at each step. We also show that for each
$G$ there is a unique attractor, a distribution of the infinite sequence of
masses, which is a fixed point of the random exchange and to which iterations
of a non-equilibrium configuration of masses converge weakly. In particular,
iteratively applying B$(r,1-r)$-divisions to a realisation of any renewal
process with finite second moment of $F$ yields a Poisson process of the same
intensity in the limit.


title: Holographic Brownian Motion in 1+1 Dimensions

abstract:
  We study the motion of a stochastic string in the background of a BTZ black
hole. In the 1+1 dimensional boundary theory this corresponds to a very heavy
external particle (e.g, a quark), interacting with the fields of a CFT at
finite temperature, and describing Brownian motion. The equations of motion for
a string in the BTZ background can be solved exactly. Thus we can use
holographic techniques to obtain the Schwinger-Keldysh Green function for the
boundary theory for the force acting on the quark. We write down the
generalized Langevin equation describing the motion of the external particle
and calculate the drag and the thermal mass shift. Interestingly we obtain
dissipation even at zero temperature for this 1+1 system. Even so, this does
not violate boost (Lorentz) invariance because the drag force on a constant
velocity quark continues to be zero. Furthermore since the Green function is
exact, it is possible to write down an effective membrane action, and thus a
Langevin equation, located at a "stretched horizon" at an arbitrary finite
distance from the horizon.


title:
On the symplectic structure over a moduli space of orbifold projective
  structures

abstract:
  Let S be a compact connected oriented orbifold surface We show that using
Bers simultaneous uniformization, the moduli space of projective structure on S
can be mapped biholomorphically onto the total space of the holomorphic
cotangent bundle of the Teichm\"uller space for S. The total space of the
holomorphic cotangent bundle of the Teichm\"uller space is equipped with the
Liouville symplectic form, and the moduli space of projective structures also
has a natural holomorphic symplectic form. The above identification is proved
to be compatible with these symplectic structures. Similar results are obtained
for biholomorphisms constructed using uniformizations provided by Schottky
groups and Earle's version of simultaneous uniformization.


title: The capture time of the hypercube

abstract:
  In the game of Cops and Robbers, the capture time of a graph is the minimum
number of moves needed by the cops to capture the robber, assuming optimal
play. We prove that the capture time of the $n$-dimensional hypercube is
$\Theta (n\ln n).$ Our methods include a novel randomized strategy for the
players, which involves the analysis of the coupon-collector problem.


title:
$\mathcal{P}\mathcal{S}$ bent functions constructed from finite
  pre-quasifield spreads

abstract:
  Bent functions are of great importance in both mathematics and information
science. The $\mathcal{P}\mathcal{S}$ class of bent functions was introduced by
Dillon in 1974, but functions belonging to this class that can be explicitly
represented are only the $\mathcal{P}\mathcal{S}_{\text{ap}}$ functions, which
were also constructed by Dillon after his introduction of the
$\mathcal{P}\mathcal{S}$ class. In this paper, a technique of using finite
pre-quasifield spread from finite geometry to construct
$\mathcal{P}\mathcal{S}$ bent functions is proposed. The constructed functions
are in similar styles with the $\mathcal{P}\mathcal{S}_{\text{ap}}$ functions.
To explicitly represent them in bivariate forms, the main task is to compute
compositional inverses of certain parametric permutation polynomials over
finite fields of characteristic 2. Concentrated on the Dempwolff-M\"uller
pre-quasifield, the Knuth pre-semifield and the Kantor pre-semifield, three new
subclasses of the $\mathcal{P}\mathcal{S}$ class are obtained. They are the
only sub-classes that can be explicitly constructed more than 30 years after
the $\mathcal{P}\mathcal{S}_{\text{ap}}$ subclass was introduced.


title: Spatiotemporal dynamics in 2D Kolmogorov flow over large domains

abstract:
  Kolmogorov flow in two dimensions - the two-dimensional Navier-Stokes
equations with a sinusoidal body force - is considered over extended periodic
domains to reveal localised spatiotemporal complexity. The flow response
mimicks the forcing at small forcing amplitudes but beyond a critical value
develops a long wavelength instability. The ensuing state is described by a
Cahn-Hilliard-type equation and as a result coarsening dynamics are observed
for random initial data. After further bifurcations, this regime gives way to
multiple attractors, some of which possess spatially-localised time dependence.
Co-existence of such attractors in a large domain gives rise to interesting
collisional dynamics which is captured by a system of 5 (1-space and 1-time)
PDEs based on a long wavelength limit. The coarsening regime reinstates itself
at yet higher forcing amplitudes in the sense that only longest-wavelength
solutions remain attractors. Eventually, there is one global longest-wavelength
attractor which possesses two localised chaotic regions - a kink and antikink -
which connect two steady one-dimensional flow regions of essentially half the
domain width each. The wealth of spatiotemporal complexity uncovered presents a
bountiful arena in which to study the existence of simple invariant localised
solutions which presumably underpin all of the observed behaviour.


title:
The Entity Registry System: Implementing 5-Star Linked Data Without the
  Web

abstract:
  Linked Data applications often assume that connectivity to data repositories
and entity resolution services are always available. This may not be a valid
assumption in many cases. Indeed, there are about 4.5 billion people in the
world who have no or limited Web access. Many data-driven applications may have
a critical impact on the life of those people, but are inaccessible to those
populations due to the architecture of today's data registries. In this paper,
we propose and evaluate a new open-source system that can be used as a
general-purpose entity registry suitable for deployment in poorly-connected or
ad-hoc environments.


title:
Cloaks, editors, and bubbles: applications of spacetime transformation
  theory

abstract:
  Spacetime or `event' cloaking was recently introduced as a concept, and the
theoretical design for such a cloak was presented for illumination by
electromagnetic waves [McCall, Favaro, Kinsler, Boardman 2011]. Here we
describe how event cloaks can be designed for simple wave systems, using either
an approximate `speed cloak' method, or an exact full-wave one. Further, we
discuss in detail many of the implications of spacetime transformation devices,
covering their (usually) directional nature, spacetime distortions (as opposed
to cloaks), and how leaky cloaks manifest themselves. We also address more
exotic concepts that follow naturally on from considerations of simple
spacetime transformation devices, such as spacetime modeling and causality
editors; and describe a proposal for implementing the
interrupt-without-interrupt concept suggested by McCall et al. We also describe
how we might make a simple time-dependent `bubbleverse' by embedding a
modulated Maxwell's Fisheye transformation device (T-device) in a flat
background spacetime.


title:
An improved maximal inequality for 2D fractional order Schr\"{o}dinger
  operators

abstract:
  The local maximal inequality for the Schr\"{o}dinger operators of order
$\a>1$ is shown to be bounded from $H^s(\R^2)$ to $L^2$ for any $s>\frac38$.
This improves the previous result of Sj\"{o}lin on the regularity of solutions
to fractional order Schr\"{o}dinger equations. Our method is inspired by
Bourgain's argument in case of $\a=2$. The extension from $\a=2$ to general
$\a>1$ confronts three essential obstacles: the lack of Lee's reduction lemma,
the absence of the algebraic structure of the symbol and the inapplicable
Galilean transformation in the deduction of the main theorem. We get around
these difficulties by establishing a new reduction lemma at our disposal and
analyzing all the possibilities in using the separateness of the segments to
obtain the analogous bilinear $L^2-$estimates. To compensate the absence of
Galilean invariance, we resort to Taylor's expansion for the phase function.
The Bourgain-Guth inequality in \cite{ref Bourgain Guth} is also rebuilt to
dominate the solution of fractional order Schr\"{o}dinger equations.


title:
Ground-state 12CO emission and a resolved jet at 115 GHz (rest-frame) in
  the radio loud quasar 3C318

abstract:
  An analysis of 44 GHz VLA observations of the z = 1.574 radio-loud quasar
3C318 has revealed emission from the redshifted J = 1 - 0 transition of the CO
molecule and spatially resolved the 6.3 kpc radio jet associated with the
quasar at 115 GHz rest-frame. The continuum-subtracted line emitter is
spatially offset from the quasar nucleus by 0.33" (2.82 kpc in projection).
This spatial offset has a significance of >8-sigma and, together with a
previously published -400 km/s velocity offset measured in the J = 2 - 1 CO
line relative to the systemic redshift of the quasar, rules out a circumnuclear
starburst or molecular gas ring and suggests that the quasar host galaxy is
either undergoing a major merger with a gas-rich galaxy or is otherwise a
highly disrupted system. If the merger scenario is correct then the event may
be in its early stages, acting as the trigger for both the young radio jets in
the quasar and a starburst in the merging galaxy. The total molecular gas mass
in the spatially offset line emitter as measured from the ground-state CO line
M_H2 = 3.7 (+/-0.4) x 10^10 (alpha_CO/0.8) M_solar. Assuming that the
line-emitter can be modelled as a rotating disk, an inclination-dependent upper
limit is derived for its dynamical mass M_dyn sin^2(i) < 3.2 x 10^9 M_solar,
suggesting that for M_H2 to remain less than M_dyn the inclination angle must
be i < 16 degrees. The far infrared and CO luminosities of 246 extragalactic
systems are collated from the literature for comparison. The high molecular gas
content of 3C318 is consistent with that of the general population of high
redshift quasars and sub-millimetre galaxies.


title:
Analytical Modelling of the Spread of Disease in Confined and Crowded
  Spaces

abstract:
  Since 1927, until recently, models describing the spread of disease have
mostly been of the SIR-compartmental type, based on the assumption that
populations are homogeneous and well-mixed. The focus of these models have
typically been on large-scale analysis of scenarios such as cities, nations or
even world scale. SIR models are appealing because of their simplicity, but
their parameters, especially the transmission rate, are complex and depend on a
number of factors, which makes it hard to predict how a change of a single
environmental, demographic, or epidemiological factor will affect the
population. Therefore, in this contribution we start to unpick the
transmission-rate parameter. Analysing the implications that arise when taking
crowd behaviour explicitly into account, we show how both the rate of infection
as well as the walking speed depend on the local crowd density around an
infected individual. The combined effect is that the rate of infection at a
population scale has an analytically tractable non-linear dependency on crowd
density. We model the spread of a hypothetical disease in a corridor and
compare our new model with a typical compartmental model, which highlights the
regime in which current models may not produce credible results.


title: Guiding synchrony through random networks

abstract:
  Sparse random networks contain structures that can be considered as diluted
feed-forward networks. Modeling of cortical circuits has shown that
feed-forward structures, if strongly pronounced compared to the embedding
random network, enable reliable signal transmission by propagating localized
(sub-network) synchrony. This assumed prominence, however, is not
experimentally observed in local cortical circuits. Here we show that nonlinear
dendritic interactions as discovered in recent single neuron experiments,
naturally enable guided synchrony propagation already in random recurrent
neural networks exhibiting mildly enhanced, biologically plausible
sub-structures.


title: How Chaotic is the Balanced State?

abstract:
  Large sparse circuits of spiking neurons exhibit a balanced state of highly
irregular activity under a wide range of conditions. It occurs likewise in
sparsely connected random networks that receive excitatory external inputs and
recurrent inhibition as well as in networks with mixed recurrent inhibition and
excitation. Here we analytically investigate this irregular dynamics in finite
networks keeping track of all individual spike times and the identities of
individual neurons. For delayed, purely inhibitory interactions we show that
the irregular dynamics is not chaotic but in fact stable. Moreover, we
demonstrate that after long transients the dynamics converges towards periodic
orbits and that every generic periodic orbit of these dynamical systems is
stable. We investigate the collective irregular dynamics upon increasing the
time scale of synaptic responses and upon iteratively replacing inhibitory by
excitatory interactions. Whereas for small and moderate time scales as well as
for few excitatory interactions, the dynamics stays stable, there is a smooth
transition to chaos if the synaptic response becomes sufficiently slow (even in
purely inhibitory networks) or the number of excitatory interactions becomes
too large. These results indicate that chaotic and stable dynamics are equally
capable of generating the irregular neuronal activity. More generally, chaos
apparently is not essential for generating high irregularity of balanced
activity, and we suggest that a mechanism different from chaos and
stochasticity significantly contributes to irregular activity in cortical
circuits.


title: Dynamics of defects in active nematics

abstract:
  Defect dynamics in a thin active nematic layer is studied by asymptotic
matching of solutions in the defect core and the far field. The analysis is
facilitated by the correspondence between the 2D nematic and complex scalar
field models. Self-propulsion and topological interactions are identified as
the primary drivers of the defect motion, surpassing the influence of both
passive backflow and active flow induced by other defects.


title: Spin heat accumulation induced by tunneling from a ferromagnet

abstract:
  An electric current from a ferromagnet into a non-magnetic material can
induce a spin-dependent electron temperature. Here it is shown that this spin
heat accumulation, when created by tunneling from a ferromagnet, produces a
non-negligible voltage signal that is comparable to that due to the coexisting
electrical spin accumulation and can give a different Hanle spin precession
signature. The effect is governed by the spin polarization of the Peltier
coefficient of the tunnel contact, its Seebeck coefficient, and the spin heat
resistance of the non-magnetic material, which is related to the electrical
spin resistance by a spin-Wiedemann-Franz law. Moreover, spin heat injection is
subject to a heat conductivity mismatch that is overcome if the tunnel
interface has a sufficiently large resistance.


title: The kaon mass in 2+1+1 flavor twisted mass Wilson ChPT

abstract:
  We construct the chiral low-energy effective theory for 2+1+1 flavor lattice
QCD with twisted mass Wilson fermions. In contrast to existing results we
assume a heavy charm quark mass such that the D mesons are too heavy to appear
as degrees of freedom in the effective theory. As an application we compute the
kaon mass to 1-loop order in the LCE regime. The result contains a chiral
logarithm involving the neutral pion mass which has no analogue in continuum
ChPT.