title: Virtual tangles and fiber functors

abstract:
  We define a category $v\mathcal{T}$ of tangles diagrams drawn on surfaces
with boundaries. On the one hand we show that there is a natural functor from
the category of virtual tangles to $v\mathcal{T}$ which induces an equivalence
of categories. On the other hand, we show that $v\mathcal{T}$ is universal
among ribbon categories equipped with a strong monoidal functor to a symmetric
monoidal category. This is a generalization of the Shum-Reshetikhin-Turaev
theorem characterizing the category of ordinary tangles as the free ribbon
category. This gives a straightforward proof that all quantum invariants of
links extends to framed oriented virtual links. This also provides a clear
explanation of the relation between virtual tangles and Etingof-Kazhdan
formalism suggested by Bar-Natan. We prove a similar statement for virtual
braids, and discuss the relation between our category and knotted trivalent
graphs.


title:
Frequency and time domain inspiral templates for comparable mass compact
  binaries in eccentric orbits

abstract:
  Inspiraling compact binaries with non-negligible orbital eccentricities are
plausible gravitational wave (GW) sources for the upcoming network of GW
observatories. In this paper, we present two prescriptions to compute
post-Newtonian (PN) accurate inspiral templates for such binaries. First, we
adapt and extend the post-circular scheme of Yunes {\it et al.} [Phys. Rev. D
80, 084001 (2009)] to obtain a Fourier-domain inspiral approximant that
incorporates the effects of PN-accurate orbital eccentricity evolution. This
results in a fully analytic frequency-domain inspiral waveform with Newtonian
amplitude and 2PN order Fourier phase while incorporating eccentricity effects
up to sixth order at each PN order. The importance of incorporating
eccentricity evolution contributions to the Fourier phase in a PN consistent
manner is also demonstrated. Second, we present an accurate and efficient
prescription to incorporate orbital eccentricity into the quasi-circular
time-domain {\texttt{TaylorT4}} approximant at 2PN order. New features include
the use of rational functions in orbital eccentricity to implement the 1.5PN
order tail contributions to the far-zone fluxes. This leads to closed form
PN-accurate differential equations for evolving eccentric orbits and the
resulting time-domain approximant is accurate and efficient to handle initial
orbital eccentricities $\leq 0.9$. Preliminary GW data analysis implications
are probed using match estimates.


title: Heterotic free fermionic and symmetric toroidal orbifold models

abstract:
  Free fermionic models and symmetric heterotic toroidal orbifolds both
constitute exact backgrounds that can be used effectively for phenomenological
explorations within string theory. Even though it is widely believed that for
Z2xZ2 orbifolds the two descriptions should be equivalent, a detailed
dictionary between both formulations is still lacking. This paper aims to fill
this gap: We give a detailed account of how the input data of both descriptions
can be related to each other. In particular, we show that the generalized GSO
phases of the free fermionic model correspond to generalized torsion phases
used in orbifold model building. We illustrate our translation methods by
providing free fermionic realizations for all Z2xZ2 orbifold geometries in six
dimensions.


title: A wild model of linear arithmetic and discretely ordered modules

abstract:
  Linear arithmetics are extensions of Presburger arithmetic (Pr) by one or
more unary functions, each intended as multiplication by a fixed element
(scalar), and containing the full induction schemes for their respective
languages. In this paper we construct a model M of the 2-linear arithmetic LA_2
(linear arithmetic with two scalars) in which an infinitely long initial
segment of "Peano multiplication" on M is 0-definable. This shows, in
particular, that LA_2 is not model complete in contrast to theories LA_1 and
LA_0=Pr that are known to satisfy quantifier elimination up to disjunctions of
primitive positive formulas. As an application, we show that M, as a discretely
ordered module over the discretely ordered ring generated by the two scalars,
is not NIP, answering negatively a question of Chernikov and Hils.


title: Local Codes with Cooperative Repair in Distributed Storage System

abstract:
  Recently, the research on local repair codes is mainly confined to repair the
failed nodes within each repair group. But if the extreme cases occur that the
entire repair group has failed, the local code stored in the failed group need
to be recovered as a whole. In this paper, local codes with cooperative repair,
in which the local codes are constructed based on minimum storage regeneration
(MSR) codes, is proposed to achieve repairing the failed groups. Specifically,
the proposed local codes with cooperative repair construct a kind of mutual
interleaving structure among the parity symbols, that the parity symbols of
each local code, named as distributed local parity, can be generated by the
parity symbols of the MSR codes in its two adjacent local codes. Taking
advantage of the structure given, the failed local groups can be repaired
cooperatively by their adjacent local groups with lower repair locality, and
meanwhile the minimum distance of local codes with cooperative repair is
derived. Theoretical analysis and simulation experiments show that, compared
with codes with local regeneration (such as MSR-local codes and MBR-local
codes), the proposed local codes with cooperative repair have benefits in
bandwidth overhead and repair locality for the case of local groups failure.


title:
Gravitational wave production from the decay of the Standard Model Higgs
  field after inflation

abstract:
  During or towards the end of inflation, the Standard Model (SM) Higgs forms a
condensate with a large amplitude. Following inflation, the condensate
oscillates, decaying non-perturbatively into the rest of the SM species. The
resulting out-of-equilibrium dynamics converts a fraction of the energy
available into gravitational waves (GW). We study this process using classical
lattice simulations in an expanding box, following the energetically dominant
electroweak gauge bosons $W^\pm$ and $Z$. We characterize the GW spectrum as a
function of the running couplings, Higgs initial amplitude, and
post-inflationary expansion rate. As long as the SM is decoupled from the
inflationary sector, the generation of this background is universally expected,
independently of the nature of inflation. Our study demonstrates the efficiency
of GW emission by gauge fields undergoing parametric resonance. The initial
energy of the Higgs condensate represents however, only a tiny fraction of the
inflationary energy. Consequently, the resulting background is very suppressed,
with an amplitude $h^2 \Omega_{\rm GW}^{(o)} \lesssim 10^{-29}$ today. The
amplitude can be boosted to $h^2 \Omega_{\rm GW}^{(o)} \lesssim 10^{-16}$, if
following inflation the universe undergoes a kination-domination stage; however
the background is shifted in this case to high frequencies $f_p \lesssim
10^{11} {\rm Hz}$. In all cases the signal is out of the range of current or
planned GW detectors. This background will therefore remain, most likely, as a
curiosity of the SM.


title: RECKONER: Read Error Corrector Based on KMC

abstract:
  Motivation: Next-generation sequencing tools have enabled producing of huge
amount of genomic information at low cost. Unfortunately, presence of
sequencing errors in such data affects quality of downstream analyzes. Accuracy
of them can be improved by performing error correction. Because of huge amount
of such data correction algorithms have to: be fast, memory-frugal, and provide
high accuracy of error detection and elimination for variously-sized organisms.
  Results: We introduce a new algorithm for genomic data correction, capable of
processing eucaryotic 300 Mbp-genome-size, high error-rated data using less
than 4 GB of RAM in less than 40 minutes on 16-core CPU. The algorithm allows
to correct sequencing data at better or comparable level than competitors. This
was achieved by using very robust KMC~2 $k$-mer counter, new method of
erroneous regions correction based on both $k$-mer counts and FASTQ quality
indicators as well as careful optimization. Availability: Program is freely
available at http://sun.aei.posl.pl/REFRESH/reckoner. Contact:
sebastian.deorowicz@polsl.pl


title: Irreducibility of a holomorphic eta quotient is determinable

abstract:
  We show that a holomorphic eta quotient has only finitely many factors. We
also provide an algorithm for checking irreducibility of holomorphic eta
quotients by constructing an upper bound for the minimum of the levels of the
proper factors of a reducible holomorphic eta quotient.


title: Transitions in the cloud composition of hot Jupiters

abstract:
  Over a large range of equilibrium temperatures, clouds shape the transmission
spectrum of hot Jupiter atmospheres, yet their composition remains unknown.
Recent observations show that the Kepler lightcurves of some hot Jupiters are
asymmetric: for the hottest planets, the lightcurve peaks before secondary
eclipse, whereas for planets cooler than $\sim1900\rm\,K$, it peaks after
secondary eclipse. We use the thermal structure from 3D global circulation
models to determine the expected cloud distribution and Kepler lightcurves of
hot Jupiters. We demonstrate that the change from an optical lightcurve
dominated by thermal emission to one dominated by scattering (reflection)
naturally explains the observed trend from negative to positive offset. For the
cool planets the presence of an asymmetry in the Kepler lightcurve is a
telltale sign of the cloud composition, because each cloud species can produce
an offset only over a narrow range of effective temperatures. By comparing our
models and the observations, we show that the cloud composition of hot Jupiters
likely varies with equilibrium temperature. We suggest that a transition occurs
between silicate and manganese sulfide clouds at a temperature near
$1600\rm\,K$, analogous to the L/T transition on brown dwarfs. The cold
trapping of cloud species below the photosphere naturally produces such a
transition and predicts similar transitions for other condensates, including
TiO. We predict that most hot Jupiters should have cloudy nightsides, that
partial cloudiness should be common at the limb and that the dayside hot spot
should often be cloud-free.


title: Main Parameters of LCxFCC Based Electron-Proton Colliders

abstract:
  Multi-TeV center of mass energy ep colliders based on the Future Circular
Collider (FCC) and linear colliders (LC) are proposed and corresponding
luminosity values are estimated. Parameters of upgraded versions of the FCC are
determined to optimize luminosity of electron-proton collisions keeping
beam-beam effects in mind. It is shown that L_{ep}\sim10^{32}\,cm^{-2}s^{-1}
can be achieved with moderate upgrade of the FCC parameters.


title:
Differentially Private Chi-Squared Hypothesis Testing: Goodness of Fit
  and Independence Testing

abstract:
  Hypothesis testing is a useful statistical tool in determining whether a
given model should be rejected based on a sample from the population. Sample
data may contain sensitive information about individuals, such as medical
information. Thus it is important to design statistical tests that guarantee
the privacy of subjects in the data. In this work, we study hypothesis testing
subject to differential privacy, specifically chi-squared tests for goodness of
fit for multinomial data and independence between two categorical variables.
  We propose new tests for goodness of fit and independence testing that like
the classical versions can be used to determine whether a given model should be
rejected or not, and that additionally can ensure differential privacy. We give
both Monte Carlo based hypothesis tests as well as hypothesis tests that more
closely follow the classical chi-squared goodness of fit test and the Pearson
chi-squared test for independence. Crucially, our tests account for the
distribution of the noise that is injected to ensure privacy in determining
significance.
  We show that these tests can be used to achieve desired significance levels,
in sharp contrast to direct applications of classical tests to differentially
private contingency tables which can result in wildly varying significance
levels. Moreover, we study the statistical power of these tests. We empirically
show that to achieve the same level of power as the classical non-private tests
our new tests need only a relatively modest increase in sample size.


title:
Enhancing the Estimation of mm-Wave Large Array Channels by Exploiting
  Spatio-Temporal Correlation and Sparse Scattering

abstract:
  In order to cope with the large path-loss exponent of mm-Wave channels, a
high beamforming gain is needed. This can be achieved with small hardware
complexity and high hardware power efficiency by Hybrid Digital-Analog (HDA)
beamforming, where a very large number $M\gg 1$ of antenna array elements
requires only a relatively small $m\ll M$ number of A/D converters and
modulators/demodulators. As such, the estimation of mm-Wave MIMO channels must
deal with two specific problems: 1) high Doppler, due to the large carrier
frequency; 2) impossibility of observing directly the M-dimensional channel
vector at the antenna array elements, due to the mentioned HDA implementation.
In this paper, we consider a novel scheme inspired by recent results on
gridless multiple measurement vectors problem in compressed sensing, that is
able to exploit the inherent mm-Wave channel sparsity in the angular domain in
order to cope with both the above problems simultaneously. Our scheme uses past
pilot-symbol observations in a window of length $T$ in order to estimate a
low-dimensional subspace that approximately contains the channel vector at the
current time. This subspace information can be used directly, in order to
separate users in the spatial domain, or indirectly, in order to improve the
estimate of the user channel vector from the current pilot-symbol observation.


title: The Tait conjecture in g(S^1xS^2)

abstract:
  The Tait conjecture states that alternating reduced diagrams of links in S^3
have the minimal number of crossings. It has been proved in 1987 by M.
Thistlethwaite, L. Kauffman and K. Murasugi studying the Jones polynomial. The
author proved an analogous result for alternating links in S^1xS^2 giving a
complete answer to this problem. In this paper we extend the result to
alternating links in the connected sum #_g(S^1xS^2) of g copies of S^1xS^2. In
S^1xS^2 and #_2(S^1xS^2) the appropriate version of the statement is true for
\Z_2-homologically trivial links, and the proof also uses the Jones polynomial.
Unfortunately in the general case the method provides just a partial result and
we are not able to say if the appropriate statement is true.


title:
The effect of environmental stochasticity on species richness in neutral
  communities

abstract:
  Environmental stochasticity is known to be a destabilizing factor, increasing
abundance fluctuations and extinction rates of populations. However, the
stability of a community may benefit from the differential response of species
to environmental variations due to the storage effect. This paper provides a
systematic and comprehensive discussion of these two contradicting tendencies,
using the metacommunity version of the recently proposed time-average neutral
model of biodiversity which incorporates environmental stochasticity and
demographic noise and allows for extinction and speciation. We show that the
incorporation of demographic noise into the model is essential to its
applicability, yielding realistic behavior of the system when fitness
variations are relatively weak. The dependence of species richness on the
strength of environmental stochasticity changes sign when the correlation time
of the environmental variations increases. This transition marks the point at
which the storage effect no longer succeeds in stabilizing the community.


title:
Analysis of new stabilized hp discontinuous Galerkin methods for
  elasticity problem

abstract:
  In the paper, we propose three new hp discontinuous Galerkin methods for the
elasticity problem and make a comparison of the three numerical methods. And we
prove the optimal order of convergence in energy norm and $L^2$-norm by the
superpenalization technique. Finally, we give a numerical example to verify our
theoretical results.


title: OpenRISC System-on-Chip Design Emulation

abstract:
  Recently the hardware emulation technique has emerged as a promising approach
to accelerating hardware verification/debugging process. To fully evaluate the
powerfulness of the emulation approach and demonstrate its potential impact, we
propose to emulate a system-on-chip (SoC) design using Mentor Graphics Veloce
emulation platform. This article presents our project setup and the results we
have achieved. The results are encouraging. ORPSoC emulation with Veloce has
more than ten times faster than hardware simulation. Our experimental results
demonstrate that Mentor Graphics Veloce has major advantages in emulation,
verification, and debugging of complicated real hardware designs, especially in
the context of SoC complexity. Through our three major tasks, we will
demonstrate that (1) Veloce can successfully emulate large-scale SoC designs;
(2) it has much better performance comparing to the state-of-the-art simulation
tools; (3) it can significantly accelerate the process of hardware verification
and debugging while maintaining full signal visibility.


title:
Correlated photon pair generation in AlGaAs nanowaveguides via
  spontaneous four-wave mixing

abstract:
  We demonstrate a source of correlated photon pairs which will have
applications in future integrated quantum photonic circuits. The source
utilizes spontaneous four-wave mixing (SFWM) in a dispersion-engineered
nanowaveguide made of AlGaAs, which has merits of negligible two-photon
absorption and low spontaneous Raman scattering (SpRS). We observe a
coincidence-to-accidental (CAR) ratio up to 177, mainly limited by propagation
losses. Experimental results agree well with theoretical predictions of the
SFWM photon pair generation and the SpRS noise photon generation. We also study
the effects from the SpRS, propagation losses, and waveguide lengths on the
quality of our source.


title: Open Sesame: The Password Hashing Competition and Argon2

abstract:
  In this document we present an overview of the background to and goals of the
Password Hashing Competition (PHC) as well as the design of its winner, Argon2,
and its security requirements and properties.


title: On the Minimum Number of Edges in Triangle-Free 5-Critical Graphs

abstract:
  Kostochka and Yancey proved that every 5-critical graph G satisfies: |E(G)|>=
(9/4)|V(G)| - 5/4. A construction of Ore gives an infinite family of graphs
meeting this bound.
  We prove that there exists e,d > 0 such that if G is a 5-critical graph, then
|E(G)| >= (9/4 + e)|V(G)|- 5/4 - dT(G), where T(G) is the maximum number of
vertex-disjoint cliques of size three or four where cliques of size four have
twice the weight of a clique of size three. As a corollary, a triangle-free
5-critical graph G satisfies: |E(G)|>=(9/4 + e)|V(G)| - 5/4.


title:
Deep observation of the NGC 1275 region with MAGIC: search of diffuse
  gamma-ray emission from cosmic rays in the Perseus cluster

abstract:
  Clusters of galaxies are expected to be reservoirs of cosmic rays (CRs) that
should produce diffuse gamma-ray emission due to their hadronic interactions
with the intra-cluster medium. The nearby Perseus cool-core cluster, identified
as the most promising target to search for such an emission, has been observed
with the MAGIC telescopes at very-high energies (VHE, E>100 GeV) for a total of
253 hr from 2009 to 2014. The active nuclei of NGC 1275, the central dominant
galaxy of the cluster, and IC 310, lying at about 0.6$^\circ$ from the centre,
have been detected as point-like VHE gamma-ray emitters during the first phase
of this campaign. We report an updated measurement of the NGC 1275 spectrum,
which is well described by a power law with a photon index of
$3.6\pm0.2_{stat}\pm0.2_{syst}$ between 90 GeV and 1.2 TeV. We do not detect
any diffuse gamma-ray emission from the cluster and set stringent constraints
on its CR population. In order to bracket the uncertainties over the CR spatial
and spectral distributions, we adopt different spatial templates and power-law
spectral indexes $\alpha$. For $\alpha=2.2$, the CR-to-thermal pressure within
the cluster virial radius is constrained to be below 1-2%, except if CRs can
propagate out of the cluster core, generating a flatter radial distribution and
releasing the CR-to-thermal pressure constraint to <20%. Assuming that the
observed radio mini-halo of Perseus is generated by secondary electrons from CR
hadronic interactions, we can derive lower limits on the central magnetic
field, $B_0$, that depend on the CR distribution. For $\alpha=2.2$,
$B_0\gtrsim5-8 \mu$G, which is below the 25 $\mu$G inferred from Faraday
rotation measurements, whereas, for $\alpha\lesssim2.1$, the hadronic
interpretation of the diffuse radio emission is in contrast with our gamma-ray
flux upper limits independently of the magnetic field strength.


title: Improving Data Quality in Intelligent Transportation Systems

abstract:
  Intelligent Transportation Systems (ITS) use data and information technology
to improve the operation of our transportation network. ITS contributes to
sustainable development by using technology to make the transportation system
more efficient; improving our environment by reducing emissions, reducing the
need for new construction and improving our daily lives through reduced
congestion. A key component of ITS is traveler information. The Oregon
Department of Transportation (ODOT) recently implemented a new traveler
information system on selected freeways to provide drivers with travel time
estimates that allow them to make more informed decisions about routing to
their destinations. The ODOT project aims to improve traffic flow and promote
efficient traffic movement, which can reduce emissions rates and improve air
quality. The new ODOT system is based on travel data collected from a
recently-increased set of sensors installed on its freeways. Our current
project investigates novel data cleaning methodologies and the integration of
those methodologies into the prediction of travel times. We use machine
learning techniques on our archive to identify suspect data, and calculate
revised travel times excluding this suspect data. We compare the resulting
travel time predictions to ground-truth data, and to predictions based on
simple, rule-based data cleaning. We report on the results of our study using
qualitative and quantitative methods.


title:
Barbara Made the News: Mining the Behavior of Crowds for Time-Aware
  Learning to Rank

abstract:
  In Twitter, and other microblogging services, the generation of new content
by the crowd is often biased towards immediacy: what is happening now. Prompted
by the propagation of commentary and information through multiple mediums,
users on the Web interact with and produce new posts about newsworthy topics
and give rise to trending topics. This paper proposes to leverage on the
behavioral dynamics of users to estimate the most relevant time periods for a
topic. Our hypothesis stems from the fact that when a real-world event occurs
it usually has peak times on the Web: a higher volume of tweets, new visits and
edits to related Wikipedia articles, and news published about the event. In
this paper, we propose a novel time-aware ranking model that leverages on
multiple sources of crowd signals. Our approach builds on two major novelties.
First, a unifying approach that given query q, mines and represents temporal
evidence from multiple sources of crowd signals. This allows us to predict the
temporal relevance of documents for query q. Second, a principled retrieval
model that integrates temporal signals in a learning to rank framework, to rank
results according to the predicted temporal relevance. Evaluation on the TREC
2013 and 2014 Microblog track datasets demonstrates that the proposed model
achieves a relative improvement of 13.2% over lexical retrieval models and 6.2%
over a learning to rank baseline.


title: Cycle-based Cluster Variational Method for Direct and Inverse Inference

abstract:
  We elaborate on the idea that loop corrections to belief propagation could be
dealt with in a systematic way on pairwise Markov random fields, by using the
elements of a cycle basis to define region in a generalized belief propagation
setting. The region graph is specified in such a way as to avoid dual loops as
much as possible, by discarding redundant Lagrange multipliers, in order to
facilitate the convergence, while avoiding instabilities associated to minimal
factor graph construction. We end up with a two-level algorithm, where a belief
propagation algorithm is run alternatively at the level of each cycle and at
the inter-region level. The inverse problem of finding the couplings of a
Markov random field from empirical covariances can be addressed region wise. It
turns out that this can be done efficiently in particular in the Ising context,
where fixed point equations can be derived along with a one-parameter log
likelihood function to minimize. Numerical experiments confirm the
effectiveness of these considerations both for the direct and inverse MRF
inference.


title: Embedding Graphs in Lorentzian Spacetime

abstract:
  Geometric approaches to network analysis combine simply defined models with
great descriptive power. In this work we provide a method for embedding
directed acyclic graphs into Minkowski spacetime using Multidimensional scaling
(MDS). First we generalise the classical MDS algorithm, defined only for
metrics with a Euclidean signature, to manifolds of any metric signature. We
then use this general method to develop an algorithm to be used on networks
which have causal structure allowing them to be embedded in Lorentzian
manifolds. The method is demonstrated by calculating embeddings for both causal
sets and citation networks in Minkowski spacetime. We finally suggest a number
of applications in citation analysis such as paper recommendation, identifying
missing citations and fitting citation models to data using this geometric
approach.


title:
A Graph Isomorphism-based Decentralized Algorithm for Modular Robot
  Configuration Formation

abstract:
  We consider the problem of configuration formation in modular robot systems
where a set of modules that are initially in different configurations and
located at different locations are required to assume appropriate positions so
that they can get into a new, user-specified, target configuration. We propose
a novel algorithm based on graph isomorphism, where the modules select
locations or spots in the target configuration using a utility-based framework,
while retaining their original configuration to the greatest extent possible,
to reduce the time and energy required by the modules to assume the target
configuration. We have shown analytically that our proposed algorithm is
complete and guarantees a Pareto-optimal allocation. Experimental simulations
of our algorithm with different number of modules in different initial
configurations and located initially at different locations, show that the
planning time of our algorithm is nominal (order of msec. for 100 modules). We
have also compared our algorithm against a market-based allocation algorithm
and shown that our proposed algorithm performs better in terms of time and
number of messages exchanged.


title: Graphical Model Sketch

abstract:
  Structured high-cardinality data arises in many domains, and poses a major
challenge for both modeling and inference. Graphical models are a popular
approach to modeling structured data but they are unsuitable for
high-cardinality variables. The count-min (CM) sketch is a popular approach to
estimating probabilities in high-cardinality data but it does not scale well
beyond a few variables. In this work, we bring together the ideas of graphical
models and count sketches; and propose and analyze several approaches to
estimating probabilities in structured high-cardinality streams of data. The
key idea of our approximations is to use the structure of a graphical model and
approximately estimate its factors by "sketches", which hash high-cardinality
variables using random projections. Our approximations are computationally
efficient and their space complexity is independent of the cardinality of
variables. Our error bounds are multiplicative and significantly improve upon
those of the CM sketch, a state-of-the-art approach to estimating probabilities
in streams. We evaluate our approximations on synthetic and real-world
problems, and report an order of magnitude improvements over the CM sketch.


title: Optimal Entry to an Irreversible Investment Plan with Non Convex Costs

abstract:
  A problem of optimally purchasing electricity at a real-valued spot price
(that is, with potentially negative cost) has been recently addressed in De
Angelis, Ferrari and Moriarty (2015) [SIAM J. Control Optim. 53(3)]. This
problem can be considered one of irreversible investment with a cost functional
which is non convex with respect to the control variable. In this paper we
study the optimal entry into this investment plan. The optimal entry policy can
have an irregular boundary arising from this non convexity, with a kinked
shape.


title: Range of (1,2) random walk in random environment

abstract:
  Consider $(1,2)$ random walk in random environment $\{X_n\}_{n\ge0}.$ In each
step, the walk jumps at most a distance $2$ to the right or a distance $1$ to
the left. For the walk transient to the right, it is proved that almost surely
$\lim_{x\rightarrow\infty}\frac{\#\{X_n:\ 0\le X_n\le x,\ n\ge0\}}{x}=\theta$
for some $0<\theta<1.$ The result shows that the range of the walk covers only
a linear proportion of the lattice of the positive half line. For the nearest
neighbor random walk in random or non-random environment, this phenomenon could
not appear in any circumstance.


title:
Investigations of non-hydrostatic, stably stratified and rapidly
  rotating flows

abstract:
  We present an investigation of rapidly rotating (small Rossby number $Ro\ll
1$) and stratified turbulence where the stratification strength is varied from
weak (large Froude number $Fr\gg1$) to strong ($Fr\ll1$). The investigation is
set in the context of a reduced model derived from the Boussinesq equations
that efficiently retains anisotropic inertia-gravity waves with order-one
frequencies and highlights a regime of wave-eddy interactions. Numerical
simulations of the reduced model are performed where energy is injected by a
stochastic forcing of vertical velocity, which forces wave modes only. The
simulations reveal two regimes characterized by the presence of well-formed,
persistent and thin turbulent layers of locally-weakened stratification at
small Froude numbers, and by the absence of layers at large Froude numbers.
Both regimes are characterized by a large-scale barotropic dipole enclosed by
small-scale turbulence. When the Reynolds number is not too large a direct
cascade of barotropic kinetic energy is observed, leading to total energy
equilibration. We examine net energy exchanges that occur through vortex
stretching and vertical buoyancy flux and diagnose the horizontal scales active
in these exchanges. We find that the baroclinic motions inject energy directly
to the largest scales of the barotropic mode, implying that the large-scale
barotropic dipole is not the end result of an inverse cascade within the
barotropic mode.


title: Number of fixed points and disjoint cycles in monotone Boolean networks

abstract:
  Given a digraph $G$, a lot of attention has been deserved on the maximum
number $\phi(G)$ of fixed points in a Boolean network $f:\{0,1\}^n\to\{0,1\}^n$
with $G$ as interaction graph. In particular, a central problem in network
coding consists in studying the optimality of the classical upper bound
$\phi(G)\leq 2^{\tau}$, where $\tau$ is the minimum size of a feedback vertex
set of $G$. In this paper, we study the maximum number $\phi_m(G)$ of fixed
points in a {\em monotone} Boolean network with interaction graph $G$. We
establish new upper and lower bounds on $\phi_m(G)$ that depends on the cycle
structure of $G$. In addition to $\tau$, the involved parameters are the
maximum number $\nu$ of vertex-disjoint cycles, and the maximum number
$\nu^{*}$ of vertex-disjoint cycles verifying some additional technical
conditions. We improve the classical upper bound $2^\tau$ by proving that
$\phi_m(G)$ is at most the largest sub-lattice of $\{0,1\}^\tau$ without chain
of size $\nu+1$, and without another forbidden-pattern of size $2\nu^{*}$.
Then, we prove two optimal lower bounds: $\phi_m(G)\geq \nu+1$ and
$\phi_m(G)\geq 2^{\nu^{*}}$. As a consequence, we get the following
characterization: $\phi_m(G)=2^\tau$ if and only if $\nu^{*}=\tau$. As another
consequence, we get that if $c$ is the maximum length of a chordless cycle of
$G$ then $2^{\nu/3^c}\leq\phi_m(G)\leq 2^{c\nu}$. Finally, with the technics
introduced, we establish an upper bound on the number of fixed points of any
Boolean network according to its signed interaction graph.


title:
Holistic Influence Maximization: Combining Scalability and Efficiency
  with Opinion-Aware Models

abstract:
  The steady growth of graph data from social networks has resulted in
wide-spread research in finding solutions to the influence maximization
problem. In this paper, we propose a holistic solution to the influence
maximization (IM) problem. (1) We introduce an opinion-cum-interaction (OI)
model that closely mirrors the real-world scenarios. Under the OI model, we
introduce a novel problem of Maximizing the Effective Opinion (MEO) of
influenced users. We prove that the MEO problem is NP-hard and cannot be
approximated within a constant ratio unless P=NP. (2) We propose a heuristic
algorithm OSIM to efficiently solve the MEO problem. To better explain the OSIM
heuristic, we first introduce EaSyIM - the opinion-oblivious version of OSIM, a
scalable algorithm capable of running within practical compute times on
commodity hardware. In addition to serving as a fundamental building block for
OSIM, EaSyIM is capable of addressing the scalability aspect - memory
consumption and running time, of the IM problem as well.
  Empirically, our algorithms are capable of maintaining the deviation in the
spread always within 5% of the best known methods in the literature. In
addition, our experiments show that both OSIM and EaSyIM are effective,
efficient, scalable and significantly enhance the ability to analyze real
datasets.


title: Boosting Information Spread: An Algorithmic Approach

abstract:
  The majority of influence maximization (IM) studies focus on targeting
influential seeders to trigger substantial information spread in social
networks. In this paper, we consider a new and complementary problem of how to
further increase the influence spread of given seeders. Our study is motivated
by the observation that direct incentives could "boost" users so that they are
more likely to be influenced by friends. We study the $k$-boosting problem
which aims to find $k$ users to boost so that the final "boosted" influence
spread is maximized. The $k$-boosting problem is different from the IM problem
because boosted users behave differently from seeders: boosted users are
initially uninfluenced and we only increase their probability to be influenced.
Our work also complements the IM studies because we focus on triggering larger
influence spread on the basis of given seeders. Both the NP-hardness of the
problem and the non-submodularity of the objective function pose challenges to
the $k$-boosting problem. To tackle the problem on general graphs, we devise
two efficient algorithms with the data-dependent approximation ratio. For the
$k$-boosting problem on bidirected trees, we present an efficient greedy
algorithm and a rounded dynamic programming that is a fully polynomial-time
approximation scheme. We conduct extensive experiments using real social
networks and synthetic bidirected trees. We show that boosting solutions
returned by our algorithms achieves boosts of influence that are up to several
times higher than those achieved by boosting solutions returned by intuitive
baselines, which have no guarantee of solution quality. We also explore the
"budget allocation" problem in our experiments. Compared with targeting seeders
with all budget, larger influence spread is achieved when we allocation the
budget to both seeders and boosted users.


title:
Existence of multi-bump solutions for a class of elliptic problems
  involving the biharmonic operator

abstract:
  Using variational methods, we establish existence of multi-bump solutions for
the following class of problems
  $$
  \left\{
  \begin{array}{l}
  \Delta^2 u +(\lambda V(x)+1)u = f(u), \quad \mbox{in} \quad \mathbb{R}^{N}, u
\in H^{2}(\mathbb{R}^{N}),
  \end{array}
  \right.
  $$ where $N \geq 1$, $\Delta^2$ is the biharmonic operator, $f$ is a
continuous function with subcritical growth and $V : \mathbb{R}^N \rightarrow
\mathbb{R}$ is a continuous function verifying some conditions.


title: Rank 2 wall-crossing and the Serre correspondence

abstract:
  We study Quot schemes of 0-dimensional quotients of sheaves on 3-folds $X$.
When the sheaf $\mathcal{R}$ is rank 2 and reflexive, we prove that the
generating function of Euler characteristics of these Quot schemes is a power
of the MacMahon function times a polynomial. This polynomial is itself the
generating function of Euler characteristics of Quot schemes of a certain
0-dimensional sheaf, which is supported on the locus where $\mathcal{R}$ is not
locally free.
  In the case $X = \mathbb{C}^3$ and $\mathcal{R}$ is equivariant, we use our
result to prove an explicit product formula for the generating function. This
formula was first found using localization techniques in previous joint work
with B. Young. Our results follow from R. Hartshorne's Serre correspondence and
a rank 2 version of a Hall algebra calculation by J. Stoppa and R.P. Thomas.


title:
Regularity of weak minimizers of the K-energy and applications to
  properness and K-stability

abstract:
  Let $(X,\omega)$ be a compact K\"ahler manifold and $\mathcal H$ the space of
K\"ahler metrics cohomologous to $\omega$. If a cscK metric exists in $\mathcal
H$, we show that all finite energy minimizers of the extended K-energy are
smooth cscK metrics, partially confirming a conjecture of Y.A. Rubinstein and
the second author. As an immediate application, we obtain that existence of a
cscK metric in $\mathcal H$ implies J-properness of the K-energy, thus
confirming one direction of a conjecture of Tian. Exploiting this properness
result we prove that an ample line bundle $(X,L)$ admitting a cscK metric in
$c_1(L)$ is $K$-polystable.


title: Towards Robustness in Residue Number Systems

abstract:
  The problem of robustly reconstructing a large number from its erroneous
remainders with respect to several moduli, namely the robust remaindering
problem, may occur in many applications including phase unwrapping, frequency
detection from several undersampled waveforms, wireless sensor networks, etc.
Assuming that the dynamic range of the large number is the maximal possible
one, i.e., the least common multiple (lcm) of all the moduli, a method called
robust Chinese remainder theorem (CRT) for solving the robust remaindering
problem has been recently proposed. In this paper, by relaxing the assumption
that the dynamic range is fixed to be the lcm of all the moduli, a trade-off
between the dynamic range and the robustness bound for two-modular systems is
studied. It basically says that a decrease in the dynamic range may lead to an
increase of the robustness bound. We first obtain a general condition on the
remainder errors and derive the exact dynamic range with a closed-form formula
for the robustness to hold. We then propose simple closed-form reconstruction
algorithms. Furthermore, the newly obtained two-modular results are applied to
the robust reconstruction for multi-modular systems and generalized to real
numbers. Finally, some simulations are carried out to verify our proposed
theoretical results.


title:
Charge transport and mobility engineering in two-dimensional transition
  metal chalcogenide semiconductors

abstract:
  Two-dimensional (2D) van der Waals semiconductors represent the thinnest, air
stable semiconducting materials known. Their unique optical, electronic and
mechanical properties hold great potential for harnessing them as key
components in novel applications for electronics and optoelectronics. However,
the charge transport behavior in 2D semiconductors is more susceptible to
external surroundings (e.g. gaseous adsorbates from air and trapped charges in
substrates) and their electronic performance is generally lower than
corresponding bulk materials due to the fact that surface and bulk coincide. In
this article, we review recent progress on the charge transport properties and
carrier mobility engineering of 2D transition metal chalcogenides, with a
particular focus on the markedly high dependence of carrier mobility on
thickness. We unveil the origin of this unique thickness dependence and
elaborate the devised strategies to master it for carrier mobility
optimization. Specifically, physical and chemical methods towards the
optimization of the major factors influencing the extrinsic transport such as
electrode/semiconductor contacts, interfacial Coulomb impurities and atomic
defects are discussed. In particular, the use of \textit{ad-hoc} molecules
makes it possible to engineer the interface with the dielectric and heal the
vacancies in such materials. By casting fresh light onto the theoretical and
experimental works, we provide a guide for improving the electronic performance
of the 2D semiconductors, with the ultimate goal of achieving technologically
viable atomically thin (opto)electronics.


title: Layering of Communication Networks and a Forward-Backward Duality

abstract:
  In layered communication networks there are only connections between
intermediate nodes in adjacent layers. Applying network coding to such networks
provides a number of benefits in theory as well as in practice. We propose a
"layering procedure" to transform an arbitrary network into a layered
structure. Furthermore, we derive a "forward-backward duality" for linear
network codes, which can be seen as an analogon to the "uplink-downlink
duality" in MIMO communication systems.


title: On integral points on degree four del Pezzo surfaces

abstract:
  We report on our investigations concerning algebraic and transcendental
Brauer-Manin obstructions to integral points on complements of a hyperplane
section in degree four del Pezzo surfaces. We discuss moreover two concepts of
an obstruction at an archimedean place. Concrete examples are given of pairs of
non-homogeneous quadratic polynomials in four variables representing (0,0) over
Q and over Z_p for all primes p, but not over Z. By blow-up, these yield cubic
polynomials in three variables all integral solutions of which satisfy a gcd
condition.


title: Extended Scalar-Tensor Theories of Gravity

abstract:
  We study new consistent scalar-tensor theories of gravity recently introduced
by Langlois and Noui with potentially interesting cosmological applications. We
derive the conditions for the existence of a primary constraint that prevents
the propagation of an additional dangerous mode associated with higher order
equations of motion. We then classify the most general, consistent
scalar-tensor theories that are at most quadratic in the second derivatives of
the scalar field. In addition, we investigate the possible connection between
these theories and (beyond) Horndeski through conformal and disformal
transformations. Finally, we point out that these theories can be associated
with new operators in the effective field theory of dark energy, which might
open up new possibilities to test dark energy models in future surveys.


title:
Characterizing the parent Hamiltonian for a complete set of orthogonal
  wave functions: An inverse quantum problem

abstract:
  We study the inverse problem of constructing an appropriate Hamiltonian from
a physically reasonable set of orthogonal wave functions for a quantum spin
system. Usually, we are given a local Hamiltonian and try to characterize the
relevant wave functions and energies (the spectrum) of the system. Here, we
take the opposite approach; starting from a collection of orthogonal wave
functions, our goal is to characterize the associated parent Hamiltonian, to
see how the wave functions and the energy values determine the structure of the
parent Hamiltonian. Specifically, we obtain (quasi) local Hamiltonians by a
complete set of (multilayer) product states and a local mapping of the energy
values to the wave functions. On the other hand, a complete set of tree wave
functions (having a tree structure) results to nonlocal Hamiltonians and
operators which flip simultaneously all the spins in a single branch of the
tree graph. We observe that even for a given set of wave functions, the energy
spectrum can significantly change the nature of interactions in the
Hamiltonian. These effects can be exploited in a quantum engineering problem
optimizing an objective functional of the Hamiltonian.


title:
Probing the sparse tails of redshift distributions with Voronoi
  tessellations

abstract:
  We introduce an algorithm to estimate the redshift distribution of a sample
of galaxies selected photometrically given a subsample with measured
spectroscopic redshifts. The approach uses a non-parametric Voronoi
tessellation density estimator to interpolate the galaxy distribution in the
redshift and photometric color space. We test the method on a mock dataset with
a known color-redshift distribution. We find that the Voronoi tessellation
estimator performs well at reconstructing the tails of the redshift
distribution of individual galaxies and gives unbiased estimates of the first
and second moments. The source code is publicly available at
http://bitbucket.org/bengranett/tailz.


title:
Robustness of quantum key distribution with discrete and continuous
  variables to channel noise

abstract:
  We study the robustness of quantum key distribution protocols using discrete
or continuous variables to the channel noise. We introduce the model of such
noise based on coupling of the signal to a thermal reservoir, typical for
continuous-variable quantum key distribution, to the discrete-variable case.
Then we perform a comparison of the bounds on the tolerable channel noise
between these two kinds of protocols using the same noise parametrization, in
the case of implementation which is perfect otherwise. Obtained results show
that continuous-variable protocols can exhibit similar robustness to the
channel noise when the transmittance of the channel is relatively high.
However, for strong loss discrete-variable protocols are superior and can
overcome even the infinite-squeezing continuous-variable protocol while using
limited nonclassical resources. The requirement on the probability of a
single-photon production which would have to be fulfilled by a practical source
of photons in order to demonstrate such superiority is feasible thanks to the
recent rapid development in this field.


title: Impact detections of temporarily captured natural satellites

abstract:
  Temporarily Captured Orbiters (TCOs) are Near-Earth Objects (NEOs) which make
a few orbits of Earth before returning to heliocentric orbits. Only one TCO has
been observed to date, 2006 RH120, captured by Earth for one year before
escaping. Detailed modeling predicts capture should occur from the NEO
population predominantly through the Sun-Earth L1 and L2 points, with 1% of
TCOs impacting Earth and approximately 0.1% of meteoroids being TCOs. Although
thousands of meteoroid orbits have been measured, none until now have
conclusively exhibited TCO behaviour, largely due to difficulties in measuring
initial meteoroid speed with sufficient precision. We report on a precise
meteor observation of January 13, 2014 by a new generation of all-sky fireball
digital camera systems operated in the Czech Republic as part of the European
Fireball Network, providing the lowest natural object entry speed observed in
decades long monitoring by networks world-wide. Modeling atmospheric
deceleration and fragmentation yields an initial mass of ~5 kg and diameter of
15 cm, with a maximum Earth-relative velocity just over 11.0 km/s. Spectral
observations prove its natural origin. Back-integration across observational
uncertainties yields a 92 - 98% probability of TCO behaviour, with close lunar
dynamical interaction. The capture duration varies across observational
uncertainties from 48 days to 5+ years. We also report on two low-speed impacts
recorded by US Government sensors, and we examine Prairie Network event PN39078
from 1965 having an extremely low entry speed of 10.9 km/s. In these cases
uncertainties in measurement and origin make TCO designation uncertain.


title: Even Delta-Matroids and the Complexity of Planar Boolean CSPs

abstract:
  The main result of this paper is a generalization of the classical blossom
algorithm for finding perfect matchings. Our algorithm can efficiently solve
Boolean CSPs where each variable appears in exactly two constraints (we call it
edge CSP) and all constraints are even $\Delta$-matroid relations (represented
by lists of tuples). As a consequence of this, we settle the complexity
classification of planar Boolean CSPs started by Dvorak and Kupec.
  Using a reduction to even $\Delta$-matroids, we then extend the tractability
result to larger classes of $\Delta$-matroids that we call efficiently
coverable. It properly includes classes that were known to be tractable before,
namely co-independent, compact, local, linear and binary, with the following
caveat: we represent $\Delta$-matroids by lists of tuples, while the last two
use a representation by matrices. Since an $n\times n$ matrix can represent
exponentially many tuples, our tractability result is not strictly stronger
than the known algorithm for linear and binary $\Delta$-matroids.


title: Singularity formation of the Yang-Mills flow

abstract:
  We study singularity structure of Yang-Mills flow in dimensions $n \geq 4$.
First we obtain a description of the singular set in terms of concentration for
a localized entropy quantity, which leads to an estimate of its Hausdorff
dimension. We develop a theory of tangent measures for the flow, which leads to
a stratification of the singular set. By a refined blowup analysis we obtain
Yang-Mills connections or solitons as blowup limits at any point in the
singular set.


title:
PIC Simulations of the Effect of Velocity Space Instabilities on
  Electron Viscosity and Thermal Conduction

abstract:
  In low-collisionality plasmas, velocity-space instabilities are a key
mechanism providing an effective collisionality for the plasma. We use
particle-in-cell (PIC) simulations to study the interplay between electron and
ion-scale velocity-space instabilities and their effect on electron pressure
anisotropy, viscous heating, and thermal conduction. The adiabatic invariance
of the magnetic moment in low-collisionality plasmas leads to pressure
anisotropy, $p_{\perp,j} > p_{||,j}$, if the magnetic field $\vec{B}$ is
amplified ($p_{\perp,j}$ and $p_{||,j}$ denote the pressure of species $j$
[electron, ion] perpendicular and parallel to $\vec{B}$). If the resulting
anisotropy is large enough, it can in turn trigger small-scale plasma
instabilities. Our PIC simulations explore the nonlinear regime of the mirror,
ion-cyclotron, and electron whistler instabilities, through continuous
amplification of the magnetic field $|\vec{B}|$ by an imposed shear in the
plasma. In the regime $1 \lesssim \beta_j \lesssim 20$ ($\beta_j \equiv 8\pi
p_j/|\vec{B}|^2$), the saturated electron pressure anisotropy, $\Delta
p_e/p_{||,e}$, is determined mainly by the (electron-lengthscale) whistler
marginal stability condition, with a modest factor of $\sim 1.5-2$ decrease due
to the trapping of electrons by the mirrors. We explicitly calculate the mean
free path of the electrons and ions along the mean magnetic field and provide a
simple physical prescription for the mean free path and thermal conductivity in
low-collisionality $\beta_j \gtrsim 1$ plasmas. Our results imply that
velocity-space instabilities likely decrease the thermal conductivity of plasma
in the outer parts of massive, hot, galaxy clusters. We also discuss the
implications of our results for electron heating and thermal conduction in
low-collisionality accretion flows onto black holes, including Sgr A* in the
Galactic Center.


title: Almost Minimal Systems and Periodicity in Hyperspaces

abstract:
  Given a self-map of a compact metric space $X$, we study periodic points of
the map induced on the hyperspace of closed subsets of $X$. We give some
necessary conditions on admissible sets of periods for these maps. Seemingly
unrelated to this, we construct an almost totally minimal homeomorphism of the
Cantor set. We also apply our theory to give a full description of admissible
period sets for induced maps of the interval maps. The description of
admissible periods is also given for maps induced on symmetric products.


title:
Room-temperature quantum transport signatures in graphene/LaAlO3/SrTiO3
  heterostructures

abstract:
  The pseudospin quantum degree of freedom is one of the most remarkable
properties of graphene that distinguishes it from ordinary two-dimensional
metals and semiconductors. Pseudospin quantum interference leads to weak
antilocalization (WAL) and is influenced strongly by point defects and thermal
perturbations that break chirality and destroy phase coherence. Preserving and
manipulating quantum transport properties up to room temperature is key to
realizing practical pseudospin-based graphene devices. Here we report
fabrication and transport characterization of graphene field-effect devices on
a complex-oxide heterostructure, LaAlO3/SrTiO3. Signatures of WAL, a
consequence of pseudospin quantum interference, persist up to room temperature.
The LaAlO3/SrTiO3 substrate plays a critical role in suppressing short-range
impurity scattering and electron-phonon coupling. The observation of quantum
transport signatures at room temperature is unique to this system and presents
new opportunities for the development of pseudospin-based devices and novel
multifunctional devices that couple to the complex-oxide interface.


title:
On Fourier time-splitting methods for nonlinear Schrodinger equations in
  the semi-classical limit II. Analytic regularity

abstract:
  We consider the time discretization based on Lie-Trotter splitting, for the
nonlinear Schrodinger equation, in the semi-classical limit, with initial data
under the form of WKB states. We show that both the exact and the numerical
solutions keep a WKB structure, on a time interval independent of the Planck
constant. We prove error estimates, which show that the quadratic observables
can be computed with a time step independent of the Planck constant. The
functional framework is based on time-dependent analytic spaces, in order to
overcome a previously encountered loss of regularity phenomenon.


title:
Hydrodynamic Simulations of the Interaction between Giant Stars and
  Planets

abstract:
  We present the results of hydrodynamic simulations of the interaction between
a 10 Jupiter mass planet and a red or asymptotic giant branch stars, both with
a zero-age main sequence mass of 3.5 $M_\odot$. Dynamic in-spiral timescales
are of the order of few years and a few decades for the red and asymptotic
giant branch stars, respectively. The planets will eventually be destroyed at a
separation from the core of the giants smaller than the resolution of our
simulations, either through evaporation or tidal disruption. As the planets
in-spiral, the giant stars' envelopes are somewhat puffed up. Based on
relatively long timescales and even considering the fact that further in-spiral
should take place before the planets are destroyed, we predict that the merger
would be difficult to observe, with only a relatively small, slow brightening.
Very little mass is unbound in the process. These conclusions may change if the
planet's orbit enhances the star's main pulsation modes. Based on the angular
momentum transfer, we also suspect that this star-planet interaction may be
unable to lead to large scale outflows via the rotation-mediated dynamo effect
of Nordhaus and Blackman. Detectable pollution from the destroyed planets would
only result for the lightest, lowest metallicity stars. We furthermore find
that in both simulations the planets move through the outer stellar envelopes
at Mach-3 to Mach-5, reaching Mach-1 towards the end of the simulations. The
gravitational drag force decreases and the in-spiral slows down at the sonic
transition, as predicted analytically.


title:
Large scale multi-objective optimization: Theoretical and practical
  challenges

abstract:
  Multi-objective optimization (MOO) is a well-studied problem for several
important recommendation problems. While multiple approaches have been
proposed, in this work, we focus on using constrained optimization formulations
(e.g., quadratic and linear programs) to formulate and solve MOO problems. This
approach can be used to pick desired operating points on the trade-off curve
between multiple objectives. It also works well for internet applications which
serve large volumes of online traffic, by working with Lagrangian duality
formulation to connect dual solutions (computed offline) with the primal
solutions (computed online).
  We identify some key limitations of this approach -- namely the inability to
handle user and item level constraints, scalability considerations and variance
of dual estimates introduced by sampling processes. We propose solutions for
each of the problems and demonstrate how through these solutions we
significantly advance the state-of-the-art in this realm. Our proposed methods
can exactly handle user and item (and other such local) constraints, achieve a
$100\times$ scalability boost over existing packages in R and reduce variance
of dual estimates by two orders of magnitude.


title:
Note on Covariant St\"uckelberg Formalism and Absence of Boulware-Deser
  Ghost in Bi-gravity

abstract:
  The covariant St\"{u}ckelberg formalism is applied to bi-gravity in order to
revisit the issue of absence of the Boulware-Deser (BD) ghost. We first confirm
that the leading order action in the decoupling limit for helicity-2 modes of
metrics and helicity-0 mode of St\"{u}ckelberg perturbations does not lead to
higher time derivative in equations of motion, which suggests the absence of
the BD ghost. By extending this method, we reconfirm that the BD ghost does not
appear for arbitrary order of the perturbations at the decoupling limit in
bi-gravity.


title:
Generalized guidance equation for peaked quantum solitons: the single
  particle case

abstract:
  We study certain non-linear generalisations of the Schr{\"o}dinger equation
which admit static solitonic 2 solutions in absence of external potential
acting on the particle. We consider a class of solutions that can be written as
a product of a solution of the linear Schr{\"o}dinger equation with a peaked
quantum soliton, in a regime where the size of the soliton is quite smaller
than the typical scale of variation of the linear wave. In the non-relativistic
limit, the solitons obey a generalized de Broglie-Bohm (dB-B) guidance
equation. In first approximation, this guidance equation reduces to the dB-B
guidance equation according to which they move at the so-called de Broglie-Bohm
velocity along the hydrodynamical flow lines of the linear Schr{\"o}dinger
wave. If we consider a spinorial electronic wave function a la Dirac, its
barycentre is predicted to move exactly in accordance with the dB-B guidance
equation.


title:
Minimum energy and the end of the inspiral in the post-Newtonian
  approximation

abstract:
  The early inspiral phase of a compact binary coalescence is well modelled by
the post-Newtonian (PN) approximation to the orbital energy and gravitational
wave flux. The transition from the inspiral phase to the plunge can be defined
by the minimum energy circular orbit (MECO). In the extreme mass-ratio limit,
up to the highest PN order known, the PN energy equals the energy of the exact
Kerr solution. However, for comparable-mass systems the MECO of the PN energy
does not exist when bodies have large spins. By including the exact Kerr limit
and recently published post-Newtonian terms we extract a well-defined minimum
of the orbital energy beyond which the plunge or merger occurs. We study the
hybrid condition for a number of cases of both black hole and neutron stars and
compare to other commonly employed definitions. Our method can be used for any
known order of the post-Newtonian series and enables the MECO condition to be
used to define the end of the inspiral phase for highly spinning, comparable
mass systems.


title: Turbulence-induced magnetic fields in shock precursors

abstract:
  Galactic cosmic rays are believed to be mostly accelerated at supernova
shocks. However, the interstellar magnetic field is too weak to efficiently
accelerate galactic cosmic rays up to the highest energies, i.e. $10^{15}$ eV.
A stronger magnetic field in the pre-shock region could provide the efficiency
required. Bell's cosmic-ray nonresonant streaming instability has been claimed
to be responsible for the amplification of precursor magnetic fields. However,
an alternative mechanism has been proposed in which the cosmic-ray pressure
gradient forms the shock precursor and drives turbulence, amplifying the
magnetic field via the small-scale dynamo. A key ingredient for the mechanism
to operate are the inhomogeneities present in the interstellar medium (ISM).
These inhomogeneities are the consequence of turbulence. In this work we
explore the magnetic field amplification in different ISM conditions through 3D
MHD numerical simulations.


title: Solvable multistate model of Landau-Zener transitions in cavity QED

abstract:
  We consider the model of a single optical cavity mode interacting with
two-level systems (spins) driven by a linearly time-dependent field. When this
field passes through values at which spin energy level splittings become
comparable to spin coupling to the optical mode, a cascade of Landau-Zener (LZ)
transitions leads to co-flips of spins in exchange for photons of the cavity.
We derive exact transition probabilities between different diabatic states
induced by such a sweep of the field.

categories: cond-mat.mes-hall math-ph math.MP quant-ph


title:
Ultra Low-Frequency Oscillations of a Solar Filament in H{\alpha}
  Revealed With the Data of the Global Oscillation Network Group (Gong)

abstract:
  The data of ground-based telescopes of Global Oscillation Network Group
(GONG) obtained in the H-alpha line provide an opportunity to study the
long-period oscillations of chromospheric filaments (quiescent prominence). For
the first time, on the base of time-series of 5 days duration, combined from
the observations of three observatories of the GONG, a new ultra-low mode, with
period between 20 and 30 hours, was reliably detected in oscillations of a
long-lived dark filament on the solar disc.


title:
Field-driven Mott gap collapse and resistive switch in correlated
  insulators

abstract:
  Mott insulators can be portrayed as "unsuccessful metals": systems in which a
strong Coulomb repulsion prevents charge conduction notwithstanding the
metal-like density of conduction electrons. The possibility to unlock such
large density of frozen carriers with an electric field offers a tantalizing
opportunity to realize new Mott-based microelectronic devices. Here we
explicitly unveil how such unlocking happens by solving a simple, yet generic,
model for correlated insulators using dynamical mean-field theory.
Specifically, we show that the electric breakdown of a Mott insulator can occur
via a first-order insulator-to-metal transition, characterized by an abrupt
gap-collapse in sharp contrast to the Zener tunneling mechanism. The switch-on
of charge conduction is due to the energetic stabilization of a metallic phase
that preexists as metastable state in equilibrium and is disconnected from the
stable insulator. Our findings rationalize recent experimental observations and
offer a guideline for future technological research.


title: Hazard analysis of human--robot interactions with HAZOP--UML

abstract:
  New safety critical systems are about to appear in our everyday life:
advanced robots able to interact with humans and perform tasks at home, in
hospitals , or at work. A hazardous behavior of those systems, induced by
failures or extreme environment conditions, may lead to catastrophic
consequences. Well-known risk analysis methods used in other critical domains
(e.g., avion-ics, nuclear, medical, transportation), have to be extended or
adapted due to the non-deterministic behavior of those systems, evolving in
unstructured environments. One major challenge is thus to develop methods that
can be applied at the very beginning of the development process, to identify
hazards induced by robot tasks and their interactions with humans. In this
paper we present a method which is based on an adaptation of a hazard
identification technique, HAZOP (Hazard Operability), coupled with a system
description notation, UML (Unified Modeling Language). This systematic approach
has been applied successfully in research projects, and is now applied by robot
manufacturers. Some results of those studies are presented and discussed to
explain the benefits and limits of our method.


title: Serre's problem on the density of isotropic fibres in conic bundles

abstract:
  Let $\pi:X\to \mathbb{P}^1_{\mathbb{Q}}$ be a non-singular conic bundle over
$\mathbb{Q}$ having $n$ non-split fibres and denote by $N(\pi,B)$ the
cardinality of the fibres of Weil height at most $B$ that possess a rational
point. Serre showed in $1990$ that a direct application of the large sieve
yields $$N(\pi,B)\ll B^2(\log B)^{-n/2}$$ and raised the problem of proving
that this is the true order of magnitude of $N(\pi,B)$ under the necessary
assumption that there exists at least one smooth fibre with a rational point.
We solve this problem for all non-singular conic bundles of rank at most $3$.
Our method comprises the use of Hooley neutralisers, estimating divisor sums
over values of binary forms, and an application of the Rosser-Iwaniec sieve.


title:
Magnetocrystalline anisotropy of Fe and Co slabs and clusters on
  SrTiO$\_3$ by first-principles

abstract:
  In this work, we present a detailed theoretical investigation of the
electronic and magnetic properties of ferromagnetic slabs and clusters
deposited on SrTiO$\_3$ via first-principles, with a particular emphasis on the
magneto-crystalline anisotropy (MCA). We found that in the case of Fe films
deposited on SrTiO$\_3$ the effect of the interface is to quench the MCA
whereas for Cobalt we observe a change of sign of the MCA from in-plane to
out-of-plane as compared to the free surface. We also find a strong enhancement
of MCA for small clusters upon deposition on a SrTiO$\_3$ substrate. The
hybridization between the substrate and the $d$-orbitals of the cluster
extending in-plane for Fe and out-of-plane for Co is at the origin of this
enhancement of MCA. As a consequence, we predict that the Fe nanocrystals (even
rather small) should be magnetically stable and are thus good potential
candidates for magnetic storage devices.


title: A problem of Ulam about magnetic fields generated by knotted wires

abstract:
  In the context of magnetic fields generated by wires, we study the connection
between the topology of the wire and the topology of the magnetic lines. We
show that a generic knotted wire has a magnetic line of the same knot type, but
that given any pair of knots there is a wire isotopic to the first knot having
a magnetic line isotopic to the second. These questions can be traced back to
Ulam in 1935.


title:
A census of dense cores in the Taurus L1495 cloud from the Herschel
  Gould Belt Survey

abstract:
  We present a catalogue of dense cores in a $\sim 4^\circ\times2^\circ$ field
of the Taurus star-forming region, inclusive of the L1495 cloud, derived from
Herschel SPIRE and PACS observations in the 70 $\mu$m, 160 $\mu$m, 250 $\mu$m,
350 $\mu$m, and 500 $\mu$m continuum bands. Estimates of mean dust temperature
and total mass are derived using modified blackbody fits to the spectral energy
distributions. We detect 525 starless cores of which $\sim10$-20% are
gravitationally bound and therefore presumably prestellar. Our census of
unbound objects is $\sim85$% complete for $M>0.015\,M_\odot$ in low density
regions ($A_V\stackrel{<}{_\sim}5$ mag), while the bound (prestellar) subset is
$\sim85$% complete for $M>0.1\,M_\odot$ overall. The prestellar core mass
function (CMF) is consistent with lognormal form, resembling the stellar system
initial mass function, as has been reported previously. All of the inferred
prestellar cores lie on filamentary structures whose column densities exceed
the expected threshold for filamentary collapse, in agreement with previous
reports. Unlike the prestellar CMF, the unbound starless CMF is not lognormal,
but instead is consistent with a power-law form below $0.3\,M_\odot$ and shows
no evidence for a low-mass turnover. It resembles previously reported mass
distributions for CO clumps at low masses ($M\stackrel{<}{_\sim}0.3\,M_\odot$).
The volume density PDF, however, is accurately lognormal except at high
densities. It is consistent with the effects of self-gravity on magnetized
supersonic turbulence. The only significant deviation from lognormality is a
high-density tail which can be attributed unambiguously to prestellar cores.


title: Regular supercuspidal representations

abstract:
  We show that, in good residual characteristic, most supercuspidal
representations of a tamely ramified reductive p-adic group G arise from pairs
(S,\theta), where S is a tame elliptic maximal torus of G, and \theta is a
character of S satisfying a simple root-theoretic property. We then give a new
expression for the roots of unity that appear in the Adler-DeBacker-Spice
character formula for these supercuspidal representations and use it to show
that this formula bears a striking resemblance to the character formula for
discrete series representations of real reductive groups. Led by this, we
explicitly construct the local Langlands correspondence for these supercuspidal
representations and prove stability and endoscopic transfer in the case of
toral representations. In large residual characteristic this gives a
construction of the local Langlands correspondence for almost all supercuspidal
representations of reductive p-adic groups.


title:
A New Spatio-Spectral Morphological Segmentation For Multi-Spectral
  Remote-Sensing Images

abstract:
  A general framework of spatio-spectral segmentation for multi-spectral images
is introduced in this paper. The method is based on classification-driven
stochastic watershed (WS) by Monte Carlo simulations, and it gives more regular
and reliable contours than standard WS. The present approach is decomposed into
several sequential steps. First, a dimensionality-reduction stage is performed
using the factor-correspondence analysis method. In this context, a new way to
select the factor axes (eigenvectors) according to their spatial information is
introduced. Then, a spectral classification produces a spectral
pre-segmentation of the image. Subsequently, a probability density function
(pdf) of contours containing spatial and spectral information is estimated by
simulation using a stochastic WS approach driven by the spectral
classification. The pdf of the contours is finally segmented by a WS controlled
by markers from a regularization of the initial classification.


title: DCM Bandits: Learning to Rank with Multiple Clicks

abstract:
  A search engine recommends to the user a list of web pages. The user examines
this list, from the first page to the last, and clicks on all attractive pages
until the user is satisfied. This behavior of the user can be described by the
dependent click model (DCM). We propose DCM bandits, an online learning variant
of the DCM where the goal is to maximize the probability of recommending
satisfactory items, such as web pages. The main challenge of our learning
problem is that we do not observe which attractive item is satisfactory. We
propose a computationally-efficient learning algorithm for solving our problem,
dcmKL-UCB; derive gap-dependent upper bounds on its regret under reasonable
assumptions; and also prove a matching lower bound up to logarithmic factors.
We evaluate our algorithm on synthetic and real-world problems, and show that
it performs well even when our model is misspecified. This work presents the
first practical and regret-optimal online algorithm for learning to rank with
multiple clicks in a cascade-like click model.


title: Microwave study of superconducting Sn films above and below percolation

abstract:
  The electronic properties of superconducting Sn films ($T_c \approx$ 3.8 K)
change significantly when reducing the film thickness down to a few nm, in
particular close to the percolation threshold. The low-energy electrodynamics
of such Sn samples can be probed via microwave spectroscopy, e.g. with
superconducting stripline resonators.
  Here we study Sn thin films, deposited via thermal evaporation -ranging in
thickness between 38 nm and 842 nm- which encompasses the percolation
transition. We use superconducting Pb stripline resonators to probe the
microwave response of these Sn films in a frequency range between 4 GHz and 20
GHz at temperatures from 7.2 K down to 1.5 K. The measured quality factor of
the resonators decreases with rising temperature due to enhanced losses. As a
function of the sample thickness we observe three regimes with significantly
different properties: samples below percolation, i.e. ensembles of disconnected
superconducting islands, exhibit dielectric properties with negligible losses,
demonstrating that macroscopic current paths are required for appreciable
dynamical conductivity of Sn at GHz frequencies. Thick Sn films, as the other
limit, lead to low-loss resonances both above and below $T_c$ of Sn, as
expected for bulk conductors. But in an intermediate thickness regime, just
above percolation and with labyrinth-like morphology of the Sn, we observe a
quite different behavior: the superconducting state has a microwave response
similar to the thicker, completely covering films with low microwave losses;
but the metallic state of these Sn films is so lossy that resonator operation
is suppressed completely.


title: Integral p-adic Hodge theory

abstract:
  We construct a new cohomology theory for proper smooth (formal) schemes over
the ring of integers of C_p. It takes values in a mixed-characteristic analogue
of Dieudonne modules, which was previously defined by Fargues as a version of
Breuil-Kisin modules. Notably, this cohomology theory specializes to all other
known p-adic cohomology theories, such as crystalline, de Rham and etale
cohomology, which allows us to prove strong integral comparison theorems.
  The construction of the cohomology theory relies on Faltings's almost purity
theorem, along with a certain functor $L\eta$ on the derived category, defined
previously by Berthelot-Ogus. On affine pieces, our cohomology theory admits a
relation to the theory of de Rham-Witt complexes of Langer-Zink, and can be
computed as a q-deformation of de Rham cohomology.


title:
Conformal Laplace superintegrable systems in 2D: polynomial invariant
  subspaces

abstract:
  2nd-order conformal superintegrable systems in $n$ dimensions are Laplace
equations on a manifold with an added scalar potential and $2n - 1$ independent
2nd order conformal symmetry operators. They encode all the information about
Helmholtz (eigenvalue) superintegrable systems in an efficient manner: there is
a 1-1 correspondence between Laplace superintegrable systems and Stackel
equivalence classes of Helmholtz superintegrable systems. In this paper we
focus on superintegrable systems in two dimensions, $n = 2$, where there are 44
Helmholtz systems, corresponding to 12 Laplace systems. For each Laplace
equation we determine the possible 2-variate polynomial subspaces that are
invariant under the action of the Laplace operator, thus leading to families of
polynomial eigenfunctions. We also study the behavior of the polynomial
invariant subspaces under a Stackel transform. The principal new results are
the details of the polynomial variables and the conditions on parameters of the
potential corresponding to polynomial solutions. The hidden gl_3-algebraic
structure is exhibited for the exact and quasi-exact systems. For physically
meaningful solutions, the orthogonality properties and normalizability of the
polynomials are presented as well. Finally, for all Helmholtz superintegrable
solvable systems we give a unified construction of 1D and 2D quasi-exactly
solvable potentials possessing polynomial solutions, and a construction of new
2D PT-symmetric potentials is established.


title:
Model Independent Approach to the Single Photoelectron Calibration of
  Photomultiplier Tubes

abstract:
  The accurate calibration of photomultiplier tubes is critical in a wide
variety of applications for which it is necessary to know the absolute number
of detected photons or precisely determine the resolution of the signal.
Conventional calibration methods rely on fitting the photomultiplier response
to a low intensity light source with analytical approximations to the single
photoelectron distribution. We show that this approach often leads to biased
estimates due to an inability to model the full distribution accurately,
especially at low charge values. We present a simple statistical method to
extract the relevant single photoelectron calibration parameters (first two
central moments) without making any assumptions about the underlying single
photoelectron distribution. We illustrate the use of this method through the
calibration of a Hamamatsu R11410 photomultiplier tube and study the accuracy
and precision of the method using Monte Carlo simulations. The method is found
to have significantly reduced bias compared to conventional methods and works
under a wide range of light intensities, making it suitable for the
simultaneous calibration of large arrays of photomultiplier tubes where uniform
illumination may not be possible.


title:
Sedna and the cloud of comets surrounding the Solar System in Milgromian
  dynamics

abstract:
  We reconsider the hypothesis of a vast cometary reservoir surrounding the
Solar System - the Oort cloud of comets - within the framework of Milgromian
Dynamics (MD or MOND). For this purpose we built a numerical model of the cloud
assuming QUMOND, a modified gravity theory of MD. In the modified gravity
versions of MD, the internal dynamics of a system is influenced by the external
gravitational field in which the system is embedded, even when this external
field is constant and uniform, a phenomenon dubbed the external field effect
(EFE). Adopting the popular pair $\nu(x)=[1-\exp(-x^{1/2})]^{-1}$ for the MD
interpolating function and $a_{0}=1.2\times10^{-10}$ m s$^{-2}$ for the MD
acceleration scale, we found that the observationally inferred Milgromian cloud
of comets is much more radially compact than its Newtonian counterpart. The
comets of the Milgromian cloud stay away from the zone where the Galactic tide
can torque their orbits significantly. However, this does not need to be an
obstacle for the injection of the comets into the inner solar system as the EFE
can induce significant change in perihelion distance during one revolution of a
comet around the Sun. Adopting constraints on different interpolating function
families and a revised value of $a_{0}$ (provided recently by the Cassini
spacecraft), the aforementioned qualitative results no longer hold, and, in
conclusion, the Milgromian cloud is very similar to the Newtonian in its
overall size, binding energies of comets and hence the operation of the
Jupiter-Saturn barrier. However, EFE torquing of perihelia still play a
significant role in the inner parts of the cloud. Consequently Sedna-like
orbits and orbits of large semi-major axis Centaurs are easily comprehensible
in MD. In MD, they both belong to the same population, just in different modes
of their evolution.


title:
The structural, elastic and optical properties of ScM (M = Rh, Cu, Ag,
  Hg) intermetallic compounds under pressure by ab initio simulations

abstract:
  The influence of pressure on the structural and elastic properties of ScM (M
= Rh, Cu, Ag, Hg) compounds has been performed by using ab initio approach
pseudopotential plane- wave method based on the density functional theory
within the generalized gradient approximation (GGA). The optical properties
have been investigated under zero pressure. It is found that the optimized
lattice parameters for all metals are in good agreement with the experimental
data and other available theoretical values.


title:
Limiting Self-Propagating Malware Based on Connection Failure Behavior
  through Hyper-Compact Estimators

abstract:
  Self-propagating malware (e.g., an Internet worm) exploits security loopholes
in software to infect servers and then use them to scan the Internet for more
vulnerable servers. While the mechanisms of worm infection and their
propagation models are well understood, defense against worms remains an open
problem. One branch of defense research investigates the behavioral difference
between worm-infected hosts and normal hosts to set them apart. One particular
observation is that a worm-infected host, which scans the Internet with
randomly selected addresses, has a much higher connection-failure rate than a
normal host. Rate-limit algorithms have been proposed to control the spread of
worms by traffic shaping based on connection failure rate. However, these
rate-limit algorithms can work properly only if it is possible to measure
failure rates of individual hosts efficiently and accurately. This paper points
out a serious problem in the prior method. To address this problem, we first
propose a solution based on a highly efficient double-bitmap data structure,
which places only a small memory footprint on the routers, while providing good
measurement of connection failure rates whose accuracy can be tuned by system
parameters. Furthermore, we propose another solution based on shared register
array data structure, achieving better memory efficiency and much larger
estimation range than our double-bitmap solution.


title:
Constraints on large-$x$ parton distributions from new weak boson
  production and deep-inelastic scattering data

abstract:
  We present a new set of leading twist parton distribution functions, referred
to as "CJ15", which take advantage of developments in the theoretical treatment
of nuclear corrections as well as new data. The analysis includes for the first
time data on the free neutron structure function from Jefferson Lab, and new
high-precision charged lepton and W-boson asymmetry data from Fermilab. These
significantly reduce the uncertainty on the d/u ratio at large values of x and
provide new insights into the partonic structure of bound nucleons.


title:
From K.A.M. Tori to Isospectral Invariants and Spectral Rigidity of
  Billiard Tables

abstract:
  This article is a part of a project investigating the relationship between
the dynamics of completely integrable or close to completely integrable
billiard tables, the integral geometry on them, and the spectrum of the
corresponding Laplace-Beltrami operators. It is concerned with new isospectral
invariants and with the spectral rigidity problem for families of
Laplace-Beltrami operators with Dirichlet, Neumann or Robin boundary
conditions, associated with C^1 families of billiard tables. We introduce a
notion of weak isospectrality for such deformations. The main dynamical
assumption on the initial billiard table is that the corresponding billiard
ball map or an iterate of it has a Kronecker invariant torus with a Diophantine
frequency and that the corresponding Birkhoff Normal Form is nondegenerate in
Kolmogorov sense. Then we obtain C^1 families of Kronecker tori with
Diophantine frequencies. If the family of the Laplace-Beltrami operators
satisfies the weak isospectral condition, we prove that the average action on
the tori and the Birkhoff Normal Form of the billiard ball maps remain the same
along the perturbation. As an application we obtain infinitesimal spectral
rigidity for Liouville billiard tables in dimensions two and three.
Applications are obtained also for strictly convex billiard tables of dimension
two as well as in the case when the initial billiard table admits an elliptic
periodic billiard trajectory. Spectral rigidity of billard tables close
elliptical billiard tables is obtained. The results are based on a construction
of C^1 families of quasi-modes associated with the Kronecker tori and on
suitable KAM theorems for C^1 families of Hamiltonians.


title:
Dielectric response and novel electromagnetic modes in three-dimensional
  Dirac semimetal films

abstract:
  Using the Kubo formalism we have calculated the local dynamic conductivity of
a bulk, i.e., three-dimensional (3D), Dirac semimetal (BDS). We obtain that at
frequencies lower than Fermi energy the metallic response in a BDS film
manifests in the existence of surface-plasmon polaritons, but at higher
frequencies the dielectric response is dominated and it occurs that a BDS film
behaves as a dielectric waveguide. At this dielectric regime we predict the
existence inside a BDS film of novel electromagnetic modes, a 3D analog of the
transverse electric waves in graphene. We also find that the dielectric
response manifests as the wide-angle passband in the mid-infrared (IR)
transmission spectrum of light incident on a BDS film, which can be used for
the interferenceless omnidirectional mid-IR filtering. The tuning of the Fermi
level of the system allows us to switch between the metallic and the dielectric
regimes and to change the frequency range of the predicted modes. This makes
BDSs promising materials for photonics and plasmonics.


title:
Evidence for Energy Supply by Active Region Spicules to the Solar
  Atmosphere

abstract:
  We investigate the role of active region spicules in the mass balance of the
solar wind and energy supply for heating the solar atmosphere. We use high
cadence observations from the Solar Optical Telescope (SOT) onboard the Hinode
satellite in the Ca II H line filter obtained on 26 January 2007. The
observational technique provides the high spatio-temporal resolution required
to detect fine structures such as spicules. We apply Fourier power spectrum and
wavelet analysis to SOT/Hinode time series of an active region data to explore
the existence of coherent intensity oscillations. The presence of coherent
waves could be an evidence for energy transport to heat the solar atmosphere.
Using time series, we measure the phase difference between two intensity
profiles obtained at two different heights, which gives information about the
phase difference between oscillations at those heights as a function of
frequency. The results of a fast Fourier transform (FFT) show peaks in the
power spectrum at frequencies in the range from 2 to 8 mHz at four different
heights (above the limb), while the wavelet analysis indicate dominant
frequencies similar to those of the Fourier power spectrum results. A coherency
study indicates the presence of coherent oscillations at about 5.5 mHz (3 min).
We measure mean phase speeds in the range 250 to 425 km/s increasing with
height.


title: The facial weak order and its lattice quotients

abstract:
  We investigate a poset structure that extends the weak order on a finite
Coxeter group $W$ to the set of all faces of the permutahedron of $W$. We call
this order the facial weak order. We first provide two alternative
characterizations of this poset: a first one, geometric, that generalizes the
notion of inversion sets of roots, and a second one, combinatorial, that uses
comparisons of the minimal and maximal length representatives of the cosets.
These characterizations are then used to show that the facial weak order is in
fact a lattice, generalizing a well-known result of A. Bj\"orner for the
classical weak order. Finally, we show that any lattice congruence of the
classical weak order induces a lattice congruence of the facial weak order, and
we give a geometric interpretation of their classes. As application, we
describe the facial boolean lattice on the faces of the cube and the facial
Cambrian lattice on the faces of the corresponding generalized associahedron.


title: Massless sunset diagrams in finite asymmetric volumes

abstract:
  This paper discusses the methods and the results used in an accompanying
paper describing the matching of effective chiral Lagrangians in dimensional
and lattice regularizations. We present methods to compute 2-loop massless
sunset diagrams in finite asymmetric volumes in the framework of these
regularizations. We also consider 1-loop sums in both regularizations,
extending the results of Hasenfratz and Leutwyler for the case of dimensional
regularization and we introduce a new method to calculate precisely the
expansion coefficients of the 1-loop lattice sums.


title:
Measurement of the difference of time-integrated CP asymmetries in $D^0
  \rightarrow K^{-} K^{+} $ and $D^0 \rightarrow \pi^{-} \pi^{+} $ decays

abstract:
  A search for CP violation in $D^0 \rightarrow K^{-} K^{+} $ and $D^0
\rightarrow \pi^{-} \pi^{+} $ decays is performed using $pp$ collision data,
corresponding to an integrated luminosity of $3~fb^{-1}$, collected using the
LHCb detector at centre-of-mass energies of 7 and $8~$TeV. The flavour of the
charm meson is inferred from the charge of the pion in $D^{*+}\rightarrow
D^0\pi^+$ and $D^{*-}\rightarrow \bar{D^0}\pi^{-}$ decays. The difference
between the CP asymmetries in $D^0 \rightarrow K^{-} K^{+} $ and $D^0
\rightarrow \pi^{-} \pi^{+} $ decays, $\Delta A_{CP} \equiv A_{CP}(K^{-} K^{+})
- A_{CP}(\pi^{-} \pi^{+})$, is measured to be $\left( -0.10 \pm 0.08(stat) \pm
0.03(syst) \right) \%$. This is the most precise measurement of a
time-integrated CP asymmetry in the charm sector from a single experiment.


title: BCJ Identities and $d$-Dimensional Generalized Unitarity

abstract:
  We present a set of relations between one-loop integral coefficients for
dimensionally regulated QCD amplitudes. Within dimensional regularization, the
combined use of color-kinematics duality and integrand reduction yields the
existence of relations between the integrand residues of partial amplitudes
with different orderings of the external particles. These relations can be
established for the cut-constructible contributions as well for the ones
responsible for rational terms. Starting from the general parametrization of
one-loop residues and applying Laurent expansion in order to extract the
coefficients of the amplitude decomposition in terms of master integrals, we
show that the full set of relations can be obtained by considering BCJ
identities between d-dimensional tree-levels. We provide explicit examples for
multi-gluon scattering amplitudes at one-loop.


title: On Kazhdan's property (T) for isotropic reductive groups

abstract:
  We show that the standard set of elementary generators of an elementary
isotropic reductive group over a connected finitely generated ring is a Kazhdan
subset. This generalizes the corresponding result of M. Ershov, A.
Jaikin-Zapirain, and M. Kassabov for Chevalley and twisted Chevalley groups.


title: Stokes Waves Revisited: Exact Solutions in the Asymptotic Limit

abstract:
  Stokes perturbative solution of the nonlinear (boundary value dependent)
surface gravity wave problem is known to provide results of reasonable accuracy
to engineers in estimating the phase speed and amplitudes of such nonlinear
waves. The weakling in this structure though is the presence of aperiodic
secular variation in the solution that does not agree with the known periodic
propagation of surface waves. This has historically necessitated increasingly
higher ordered (perturbative) approximations in the representation of the
velocity profile. The present article ameliorates this long standing
theoretical insufficiency by invoking a compact exact $n$-ordered solution in
the asymptotic infinite depth limit, primarily based on a representation
structured around the third ordered perturbative solution, that leads to a
seamless extension to higher order (e.g. fifth order) forms existing in the
literature. The result from this study is expected to improve phenomenological
engineering estimates, now that any desired higher ordered expansion may be
compacted within the same representation, but without any aperiodicity in the
spectral pattern of the wave guides.


title:
Universal deformation rings for extensions of finite subgoups of
  $Gl_2(\mathbb{C})$

abstract:
  In this paper we expand on previous results, studying the extent to which one
can detect fusion in certain finite groups $\Gamma$, from information about the
universal deformation rings of absolutely irreducible
$\mathbb{F}_p\Gamma$-modules. We consider groups which are extensions of finite
irreducible subgroups of $Gl_2({\mathbb{C}})$ by elementary abelian $p$-groups
of rank $2$.


title: Spectra for cubes in products of finite cyclic groups

abstract:
  We consider "cubes" in products of finite cyclic groups and we study their
tiling and spectral properties. (A set in a finite group is called a tile if
some of its translates form a partition of the group and is called spectral if
it admits an orhogonal basis of characters for the functions supported on the
set.) We show an analog of a theorem due to Iosevich and Pedersen, Lagarias,
Reeds and Wang, and the third author of this paper, which identified the tiling
complements of the unit cube in Euclidean space with the spectra of the same
cube.


title:
Proceedings, 2011 European School of High-Energy Physics (ESHEP 2011):
  Cheile Gradistei, Romania, September 7-20, 2011

abstract:
  The European School of High-Energy Physics is intended to give young
physicists an introduction to the theoretical aspects of recent advances in
elementary particle physics. These proceedings contain lecture notes on quantum
field theory and the Standard Model, quantum chromodynamics, flavour physics,
neutrino physics, physics beyond the Standard Model, cosmology, heavy ion
physics, statistical data analysis, as well as an account for the physics
results with the data accumulated during the first run of the LHC.


title:
Finding the effective structure parameters for suspensions of nano-sized
  insulating particles from low-frequency impedance measurements

abstract:
  Based on the method of compact groups of inhomogeneities, we formulate new
mixing rules for suspensions of charged insulating particles. They express the
quasistatic conductivity and permittivity of a suspension in terms of the
effective geometric and dielectric parameters of the particles, electric double
layers (EDLs), and suspending liquid. Also, we present our low-frequency
impedance measurements of the conductivity and permittivity of Al2O3-isopropyl
alcohol nanofluids as functions of Al2O3-particle volume concentration. Our
rules give good fits for most of these data and allow us to estimate, among
other things, the effective thickness, conductivity, and permittivity of the
EDLs. The experimentally-recovered values agree well with elementary
theoretical estimates suggesting the charging of the particles through
preferential adsorption of contaminant ions. The possible effects of other
mechanisms on the effective conductivity and permittivity of suspensions are
also discussed.


title:
A statistical physics perspective on alignment-independent protein
  sequence comparison

abstract:
  Within bioinformatics, the textual alignment of amino acid sequences has long
dominated the determination of similarity between proteins, with all that
implies for shared structure, function and evolutionary descent. Despite the
relative success of modern-day sequence alignment algorithms, so-called
alignment-free approaches offer a complementary means of determining and
expressing similarity, with potential benefits in certain key applications,
such as regression analysis of protein structure-function studies, where
alignment-base similarity has performed poorly. Here, we offer a fresh,
statistical physics-based perspective focusing on the question of
alignment-free comparison, in the process adapting results from 'first passage
probability distribution' to summarize statistics of ensemble averaged amino
acid propensity values. In this article, we introduce and elaborate this
approach.


title:
Search for direct pair production of scalar top quarks in the single-
  and dilepton channels in proton-proton collisions at sqrt(s) = 8 TeV

abstract:
  Results are reported from a search for the top squark, the lighter of the two
supersymmetric partners of the top quark. The data sample corresponds to 19.7
inverse femtobarns of proton-proton collisions at sqrt(s) = 8 TeV collected
with the CMS detector at the LHC. The search targets top squark to b chi+/- and
top squark to t(*) chi0 decay modes, where chi+/- and chi0 are the lightest
chargino and neutralino, respectively. The reconstructed final state consists
of jets, b jets, missing transverse energy, and either one or two leptons.
Leading backgrounds are determined from data. No significant excess in data is
observed above the expectation from standard model processes. The results
exclude a region of the two-dimensional plane of possible top squark and chi0
masses. The highest excluded top squark and chi0 masses are about 700 GeV and
250 GeV, respectively.