title:
Atmospheric ionization by high-fluence, hard spectrum solar proton
  events and their probable appearance in the ice core archive

abstract:
  Solar energetic particles ionize the atmosphere, leading to production of
nitrogen oxides. It has been suggested that some such events are visible as
layers of nitrate in ice cores, yielding archives of energetic, high fluence
solar proton events (SPEs). There has been controversy, due to slowness of
transport for these species down from the upper stratosphere; past numerical
simulations based on an analytic calculation have shown very little ionization
below the mid stratosphere. These simulations suffer from deficiencies: they
consider only soft SPEs and narrow energy ranges; spectral fits are poorly
chosen; with few exceptions secondary particles in air showers are ignored.
Using improved simulations that follow development of the proton-induced air
shower, we find consistency with recent experiments showing substantial excess
ionization down to 5 km. We compute nitrate available from the 23 February 1956
SPE, which had a high fluence, hard spectrum, and well-resolved associated
nitrate peak in a Greenland ice core. For the first time, we find this event
can account for ice core data with timely (~ 2 months) transport downward
between 46 km and the surface, thus indicating an archive of high fluence, hard
spectrum SPE covering the last several millennia. We discuss interpretations of
this result, as well as the lack of a clearly-defined nitrate spike associated
with the soft-spectrum 3-4 August 1972 SPE. We suggest that hard-spectrum SPEs,
especially in the 6 months of polar winter, are detectable in ice cores, and
that more work needs to be done to investigate this.

categories: physics.ao-ph astro-ph.EP astro-ph.IM astro-ph.SR physics.geo-ph


title:
Green Scale Research Tool for Multi-Criteria and Multi-Metric Energy
  Analysis Performed During the Architectural Design Process

abstract:
  Prevailing computational tools available to and used by architecture and
engineering professionals purport to gather and present thorough and accurate
perspectives of the environmental impacts associated with their contributions
to the built environment. The presented research of building modeling and
analysis software used by the Architecture, Engineering, Construction, and
Operations (AECO) industry reveals that many of the most heavily relied-upon
industry tools are isolated in functionality, utilize incomplete models and
data, and are disruptive to normative design and building optimization
workflows. This paper describes the current models and tools, their primary
functions and limitations, and presents our concurrent research to develop more
advanced models to assess lifetime building energy consumption alongside
operating energy use. A series of case studies describes the current
state-of-the-art in tools and building energy analysis followed by the research
models and novel design and analysis Tool that the Green Scale Research Group
has developed in response. A fundamental goal of this effort is to increase the
use and efficacy of building impact studies conducted by architects, engineers,
and building owners and operators during the building design process.


title: Optical Kerr Spatio-Temporal Dark-Lump Dynamics of Hydrodynamic Origin

abstract:
  There is considerable fundamental and applicative interest in obtaining
non-diffractive and non-dispersive spatio-temporal localized wave packets
propagating in optical cubic nonlinear or Kerr media. Here, we analytically
predict the existence of a novel family of spatio-temporal dark lump solitary
wave solutions of the (2+1)D nonlinear Schr\"odinger equation. Dark lumps
represent multi-dimensional holes of light on a continuous wave background. We
analytically derive the dark lumps from the hydrodynamic exact soliton
solutions of the (2+1)D shallow water Kadomtsev-Petviashvili model, inheriting
their complex interaction properties. This finding opens a novel path for the
excitation and control of optical multidimensional extreme wave phenomena of
hydrodynamic footprint.


title: Seq-NMS for Video Object Detection

abstract:
  Video object detection is challenging because objects that are easily
detected in one frame may be difficult to detect in another frame within the
same clip. Recently, there have been major advances for doing object detection
in a single image. These methods typically contain three phases: (i) object
proposal generation (ii) object classification and (iii) post-processing. We
propose a modification of the post-processing phase that uses high-scoring
object detections from nearby frames to boost scores of weaker detections
within the same clip. We show that our method obtains superior results to
state-of-the-art single image object detection techniques. Our method placed
3rd in the video object detection (VID) task of the ImageNet Large Scale Visual
Recognition Challenge 2015 (ILSVRC2015).


title:
Range Assignment for Power Optimization in Load-Coupled Heterogeneous
  Networks

abstract:
  We consider the problem of transmission energy op- timization via range
assignment for Low Power Nodes (LPNs) in Long Term Evolution (LTE) Heterogenous
Networks (HetNets). The optimization is subject to the load coupling model,
where the cells interfere with one another. Each cell provides data service for
its users so as to maintain a target Quality-of-Service (QoS). We prove that,
irrespective the presence of maximum power limit or its value, operating at
full load is optimal. We perform energy minimization by optimizing the
association between User Equipments (UEs) and cells via selecting cell-
specific offsets on LPNs. Moreover, the optimization problem is proved to be
NP-hard. We propose a tabu search algorithm for offset optimization (TSO). For
each offset, TSO computes the optimal power solution such that all cells
operate at full load. Numerical results demonstrate the significant performance
improvement of TSO on optimizing the sum transmission energy, compared to the
conventional solution where uniform offset is used for all LPNs.


title: Microscopic models for the study of taxpayer audit effects

abstract:
  A microscopic dynamic model is here constructed and analyzed, describing the
evolution of the income distribution in the presence of taxation and
redistribution in a society in which also tax evasion and auditing processes
occur. The focus is on effects of enforcement regimes, characterized by
different choices of the audited taxpayer fraction and of the penalties imposed
to noncompliant individuals. A complex systems perspective is adopted: society
is considered as a system composed by a large number of heterogeneous
individuals. These are divided into income classes and may as well have
different tax evasion behaviors. The variation in time of the number of
individuals in each class is described by a system of nonlinear differential
equations of the kinetic discretized Boltzmann type involving transition
probabilities.


title: Topological conjugacy of linear systems on Lie groups

abstract:
  In this paper we study a classification of linear systems on Lie groups with
respect to the conjugacy of the corresponding flows. We also describe stability
according to Lyapunov exponents.


title:
A Performance Study of Energy Minimization for Interleaved and Localized
  FDMA

abstract:
  Optimal channel allocation is a key performance engineering aspect in
single-carrier frequency-division multiple access (SC-FDMA). It is of
significance to consider minimum sum power (Min-Power), subject to meeting
specified user's demand, since mobile users typically employ battery-powered
handsets. In this paper, we prove that Min-Power is polynomial-time solvable
for interleaved SC-FDMA (IFDMA). Then we propose a channel allocation algorithm
for IFDMA, which is guaranteed to achieve global optimum in polynomial time. We
numerically compare the proposed algorithm with optimal localized SC-FDMA
(LFDMA) for Min-Power. The results show that LFDMA outperforms IFDMA in the
maximal supported user demand. When the user demand can be satisfied in both
LFDMA and IFDMA, LFDMA performs slightly better than IFDMA. However Min- Power
is polynomial-time solvable for IFDMA whereas it is not for LFDMA.


title:
The magnetic monopole and the separation between fast and slow magnetic
  degrees of freedom

abstract:
  The Landau-Lifshitz-Gilbert (LLG) equation that describes the dynamics of a
macroscopic magnetic moment finds its limit of validity at very short times.
The reason for this limit is well understood in terms of separation of the
characteristic time scales between slow degrees of freedom (the magnetization)
and fast degrees of freedom. The fast degrees of freedom are introduced as the
variation of the angular momentum responsible for the inertia. In order to
study the effect of the fast degrees of freedom on the precession, we calculate
the geometric phase of the magnetization (i.e. the Hannay angle) and the
corresponding magnetic monopole. In the case of the pure precession (the slow
manifold), a simple expression of the magnetic monopole is given as a function
of the slowness parameter, i.e. as a function of the ratio of the slow over the
fast characteristic times.


title:
Reflection matrices, coideal subalgebras and generalized Satake diagrams
  of affine type

abstract:
  We present a generalization of the theory of quantum symmetric pairs as
developed by Kolb and Letzter. We introduce a class of generalized Satake
diagrams that give rise to (not necessarily involutive) automorphisms of the
second kind of symmetrizable Kac-Moody algebras $\mathfrak{g}$. These lead to
right coideal subalgebras $B_{\mathbf{c},\mathbf{s}}$ of quantized enveloping
algebras $U_q(\mathfrak{g})$. In the case that $\mathfrak{g}$ is a twisted or
untwisted affine Lie algebra of classical type Jimbo found intertwiners
(equivariant maps) of the vector representation of $U_q(\mathfrak{g})$ yielding
trigonometric solutions to the parameter-dependent quantum Yang-Baxter
equation. In the present paper we compute intertwiners of the vector
representation restricted to the subalgebras $B_{\mathbf{c},\mathbf{s}}$ when
$\mathfrak{g}$ is of type ${\rm A}^{(1)}_n$, ${\rm B}^{(1)}_n$, ${\rm
C}^{(1)}_n$ and ${\rm D}^{(1)}_n$. These intertwiners are matrix solutions to
the parameter-dependent quantum reflection equation known as trigonometric
reflection matrices. They are symmetric up to conjugation by a diagonal matrix
and in many cases satisfy a certain sparseness condition: there are at most two
nonzero entries in each row and column. Conjecturally, this classifies all such
solutions in vector spaces carrying this representation. A group of Hopf
algebra automorphisms of $U_q(\mathfrak{g})$ acts on these reflection matrices,
allowing us to show that each reflection matrix found is equivalent to one with
at most two additional free parameters. Additional characteristics of the
reflection matrices such as eigendecompositions and affinization relations are
also obtained. The eigendecompositions suggest that for all these matrices
there should be a natural interpretation in terms of representations of
Hecke-type algebras.


title:
ExpSOS: Secure and Verifiable Outsourcing of Exponentiation Operations
  for Mobile Cloud Computing

abstract:
  Discrete exponential operation, such as modular exponentiation and scalar
multiplication on elliptic curves, is a basic operation of many public-key
cryptosystems. However, the exponential operations are considered prohibitively
expensive for resource-constrained mobile devices. In this paper, we address
the problem of secure outsourcing of exponentiation operations to one single
untrusted server. Our proposed scheme (ExpSOS) only requires very limited
number of modular multiplications at local mobile environment thus it can
achieve impressive computational gain. ExpSOS also provides a secure
verification scheme with probability approximately 1 to ensure that the mobile
end-users can always receive valid results. The comprehensive analysis as well
as the simulation results in real mobile device demonstrates that our proposed
ExpSOS can significantly improve the existing schemes in efficiency, security
and result verifiability. We apply ExpSOS to securely outsource several
cryptographic protocols to show that ExpSOS is widely applicable to many
cryptographic computations.


title:
Modeling, Minimizing and Managing the Risk of Fatigue for Mechanical
  Components

abstract:
  Mechanical components that are exposed to cyclic mechanical loading fail at
loads that are well below the ultimate tensile strength. This process is known
as fatigue. The failure time, that is the time when a first crack forms, is
highly random. In this work we review some recent developments in the modelling
of probabilistic failure times, understood as the time to the formation of a
fatigue crack.
  We also discuss the how probabilistic models can be used in shape design with
the design intent of optimizing the component's reliability. We give review a
recent existence result for optimal shapes and we discuss continuous and
discrete shape derivatives. Another application is optimal service scheduling.
The mathematical fields involved range from reliability statistics over
stochastic point processes, multiscale modeling, PDEs on variable geometries,
shape optimization and numerical analysis to operations research.


title:
On the nature of diffuse ionized gas in galaxies -- I The contribution
  of dust scattering to diffuse line emission

abstract:
  In this work, we investigate the contribution of dust scattering to the
diffuse H-alpha emission observed in nearby galaxies. As initial conditions for
the spatial distribution of HII regions, gas, and dust, we take three Milky
Way-like galaxies from state-of-the-art cosmological hydrodynamical simulations
that implement different prescriptions for star formation, feedback, and
chemical enrichment. Radiative transfer has been solved a posteriori, using the
publicly-available Monte Carlo code Sunrise to take into account dust
absorption and scattering of the H-alpha photons, originating exclusively from
the HII regions. No contribution from recombinations in the diffuse ionized gas
(DIG) component is explicitly or implicitly included in our model. Our main
result is that the flux arising from scattered light is of the order of 1-2 per
cent of the H-alpha flux coming directly from the HII regions. Building upon
previous studies, we conclude that the DIG contributes lass than 50 per cent of
the total H-alpha emission.


title: Gravitational theories with stable (anti-)de Sitter backgrounds

abstract:
  In this article we will construct the most general torsion-free
parity-invariant covariant theory of gravity that is free from ghost-like and
tachyonic nstabilities around constant curvature space-times in four
dimensions. Specifically, this includes the Minkowski, de Sitter and anti-de
Sitter backgrounds. We will first argue in details how starting from a general
covariant action for the metric one arrives at an "equivalent" action that at
most contains terms that are quadratic in curvatures but nevertheless is
sufficient for the purpose of studying stability of the original action. We
will then briefly discuss how such a "quadratic curvature action" can be
decomposed in a covariant formalism into separate sectors involving the tensor,
vector and scalar modes of the metric tensor; most of the details of the
analysis however, will be presented in an accompanying paper. We will find that
only the transverse and trace-less spin-2 graviton with its two helicity states
and possibly a spin-0 Brans-Dicke type scalar degree of freedom are left to
propagate in 4 dimensions. This will also enable us to arrive at the
consistency conditions required to make the theory perturbatively stable around
constant curvature backgrounds.
  This will be included as a chapter in the book entitled "At the Frontier of
Spacetime - Scalar-Tensor Theory, Bells Inequality, Machs Principle, Exotic
Smoothness" (Springer 2016)


title:
Holographic Conductivity for Logarithmic Charged Dilaton-Lifshitz
  Solutions

abstract:
  We disclose the effects of the logarithmic nonlinear electrodynamics on the
holographic conductivity of Lifshitz dilaton black holes/branes. We analyze
thermodynamics of these solutions as a necessary requirement for applying
gauge/gravity duality, by calculating conserved and thermodynamic quantities
such as the temperature, entropy, electric potential and mass of the black
holes/branes. We calculate the holographic conductivity for a
$(2+1)$-dimensional brane boundary and study its behavior in terms of the
frequency per temperature. Interestingly enough, we find out that, in contrast
to the Lifshitz-Maxwell-dilaton black branes which has conductivity for all
$z$, here in the presence of nonlinear gauge field, the holographic
conductivity do exist provided $z\leq3$ and vanishes for $z>3$. It is shown
that independent of the nonlinear parameter $\beta$, the real part of the
conductivity is the same for a specific value of frequency per temperature in
both AdS and Lifshitz cases. Besides, the behavior of real part of conductivity
for large frequencies has a positive slope with respect to large frequencies
for a system with Lifshitz symmetry whereas it tends to a constant for a system
with AdS symmetry. This behavior may be interpreted as existence of an
additional charge carrier rather than the AdS case, and is due to the presence
of the scalar dilaton field in model. Similar behavior for optical conductivity
of single-layer graphene induced by mild oxygen plasma exposure has been
reported.


title: Alpaka - An Abstraction Library for Parallel Kernel Acceleration

abstract:
  Porting applications to new hardware or programming models is a tedious and
error prone process. Every help that eases these burdens is saving developer
time that can then be invested into the advancement of the application itself
instead of preserving the status-quo on a new platform.
  The Alpaka library defines and implements an abstract hierarchical redundant
parallelism model. The model exploits parallelism and memory hierarchies on a
node at all levels available in current hardware. By doing so, it allows to
achieve platform and performance portability across various types of
accelerators by ignoring specific unsupported levels and utilizing only the
ones supported on a specific accelerator. All hardware types (multi- and
many-core CPUs, GPUs and other accelerators) are supported for and can be
programmed in the same way. The Alpaka C++ template interface allows for
straightforward extension of the library to support other accelerators and
specialization of its internals for optimization.
  Running Alpaka applications on a new (and supported) platform requires the
change of only one source code line instead of a lot of \#ifdefs.


title:
The AMBRE Project: Stellar Parameterisation of the ESO:UVES archived
  spectra

abstract:
  The AMBRE Project is a collaboration between the European Southern
Observatory (ESO) and the Observatoire de la Cote d'Azur (OCA) that has been
established in order to carry out the determination of stellar atmospheric
parameters for the archived spectra of four ESO spectrographs.
  The analysis of the UVES archived spectra for their stellar parameters has
been completed in the third phase of the AMBRE Project. From the complete
ESO:UVES archive dataset that was received covering the period 2000 to 2010,
51921 spectra for the six standard setups were analysed. The AMBRE analysis
pipeline uses the stellar parameterisation algorithm MATISSE to obtain the
stellar atmospheric parameters. The synthetic grid is currently constrained to
FGKM stars only.
  Stellar atmospheric parameters are reported for 12,403 of the 51,921 UVES
archived spectra analysed in AMBRE:UVES. This equates to ~23.9% of the sample
and ~3,708 stars. Effective temperature, surface gravity, metallicity and alpha
element to iron ratio abundances are provided for 10,212 spectra (~19.7%),
while at least effective temperature is provided for the remaining 2,191
spectra. Radial velocities are reported for 36,881 (~71.0%) of the analysed
archive spectra. Typical external errors of sigmaTeff~110dex,
sigmalogg~0.18dex, sigma[M/H]~0.13dex, and sigma[alpha/Fe]~0.05dex with some
reported variation between giants and dwarfs and between setups are reported.
  UVES is used to observe an extensive collection of stellar and non-stellar
objects all of which have been included in the archived dataset provided to OCA
by ESO. The AMBRE analysis extracts those objects which lie within the FGKM
parameter space of the AMBRE slow rotating synthetic spectra grid. Thus by
homogeneous blind analysis AMBRE has successfully extracted and parameterised
the targeted FGK stars (23.9% of the analysed sample) from within the ESO:UVES
archive.


title: The proper motion of HV2112: A T\.ZO candidate in the SMC

abstract:
  The candidate Thorne-\.Zytkow object (T\.ZO), HV2112, is becoming a
well-studied if enigmatic object. A key point of its candidacy as a T\.ZO is
whether or not it resides in the Small Magellanic Cloud (SMC). HV2112 has
detections in a series of photometric catalogues which have resulted in
contradictory estimates of its proper motion and, therefore, its membership
within the SMC. This letter seeks to resolve the issue of the SMC membership of
HV2112 through a reanalysis of extant photometric data. We also demonstrate the
difficulties and downfalls inherent in considering a range of catalogue proper
motions. We conclude that the proper motion, and associated ancillary radial
velocity, positional and photometric properties, are fully consistent with
HV2112 being within the SMC and thus it remains a candidate T\.ZO.


title:
Coulomb enhancement of superconducting pair-pair correlations in a
  $\frac{3}{4}$-filled model for $\kappa$-(BEDT-TTF)$_2$X

abstract:
  We present the results of precise correlated-electron calculations on the
monomer lattices of the organic charge-transfer solids $\kappa$-(BEDT-TTF)$_2$X
for 32 and 64 molecular sites. Our calculations are for band parameters
corresponding to X = Cu[N(CN)$_2$]Cl and Cu$_2$(CN)$_3$, which are
semiconducting antiferromagnetic and quantum spin liquid, respectively, at
ambient pressure. We have performed our calculations for variable electron
densities $\rho$ per BEDT-TTF molecule, with $\rho$ ranging from 1 to 2. We
find that $d$-wave superconducting pair-pair correlations are enhanced by
electron-electron interactions only for a narrow carrier concentration about
$\rho=1.5$, which is precisely the carrier concentration where
superconductivity in the charge-transfer solids occurs. Our results indicate
that the enhancement in pair-pair correlations is not related to
antiferromagnetic order, but to a proximate hidden spin-singlet state that
manifests itself as a charge-ordered state in other charge-transfer solids.
Long-range superconducting order does not appear to be present in the purely
electronic model, suggesting that electron-phonon interactions also must play a
role in a complete theory of superconductivity.


title: On the Distributed Complexity of Large-Scale Graph Computations

abstract:
  Motivated by the increasing need to understand the distributed algorithmic
foundations of large-scale graph computations, we study some fundamental graph
problems in a message-passing model for distributed computing where $k \geq 2$
machines jointly perform computations on graphs with $n$ nodes (typically, $n
\gg k$). The input graph is assumed to be initially randomly partitioned among
the $k$ machines, a common implementation in many real-world systems.
Communication is point-to-point, and the goal is to minimize the number of
communication {\em rounds} of the computation.
  Our main contribution is the {\em General Lower Bound Theorem}, a theorem
that can be used to show non-trivial lower bounds on the round complexity of
distributed large-scale data computations. The General Lower Bound Theorem is
established via an information-theoretic approach that relates the round
complexity to the minimal amount of information required by machines to solve
the problem. Our approach is generic and this theorem can be used in a
"cookbook" fashion to show distributed lower bounds in the context of several
problems, including non-graph problems. We present two applications by showing
(almost) tight lower bounds for the round complexity of two fundamental graph
problems, namely {\em PageRank computation} and {\em triangle enumeration}. Our
approach, as demonstrated in the case of PageRank, can yield tight lower bounds
for problems (including, and especially, under a stochastic partition of the
input) where communication complexity techniques are not obvious.
  Our approach, as demonstrated in the case of triangle enumeration, can yield
stronger round lower bounds as well as message-round tradeoffs compared to
approaches that use communication complexity techniques.


title:
In-situ evidence of electron energization in the electron diffusion
  region of magnetotail reconnection

abstract:
  Magnetic reconnection is an explosive energy-release process in laboratory,
space and astrophysical plasmas. While magnetic fields can `break' and
`reconnect' in a very small region called the electron diffusion region (EDR),
there have been conflicting theories as to whether this region can be a place
of rapid energization of plasmas. Here we report a fortuitous encounter of the
EDR by THEMIS in the Earth's magnetotail where significant heating and
demagnetization of electrons were observed. Additional energization was
observed on both sides (immediate upstream and downstream) of the EDR, leading
to a total of more than an order of magnitude energization across this region.
The results demonstrate that, despite its minuscule size, the EDR does indeed
contribute to the overall process of electron energization via magnetic
reconnection.


title: Electronic correlations in monolayer VS$_2$

abstract:
  The layered transition metal dichalcogenide vanadium disulfide (VS$_2$),
which nominally has one electron in the $3d$ shell, is potent for strong
correlation physics and is possibly another realization of an effective
one-band model beyond the cuprates. Here monolayer VS$_2$ in both the trigonal
prismatic and octahedral phases is investigated using density functional theory
plus Hubbard $U$ (DFT+$U$) calculations. Trigonal prismatic VS$_2$ has an
isolated low-energy band that emerges from a confluence of crystal field
splitting and direct V--V hopping. Within spin density functional theory,
ferromagnetism splits the isolated band of the trigonal prismatic structure,
leading to a low-band-gap $S=1/2$ ferromagnetic Stoner insulator; the
octahedral phase is higher in energy. Including the on-site interaction $U$
increases the band gap, leads to Mott insulating behavior, and for sufficiently
high values stabilizes the ferromagnetic octahedral phase. The validity of DFT
and DFT+$U$ for these two-dimensional materials with potential for strong
electronic correlations is discussed. A clear benchmark is given by examining
the experimentally observed charge density wave (CDW) in octahedral VS$_2$, for
which DFT grossly overestimates the bond length differences compared to known
experiments; the presence of CDWs is also probed for the trigonal prismatic
phase. Finally, we investigate why only the octahedral phase has been observed
in experiments and discuss the possibility of realizing the trigonal prismatic
phase. Our work suggests trigonal prismatic VS$_2$ is a promising candidate for
strongly correlated electron physics that, if realized, could be experimentally
probed in an unprecedented fashion due to its monolayer nature.


title: Noncommutative K\"ahler Structures on Quantum Homogeneous Spaces

abstract:
  Building on the theory of noncommutative complex structures, the notion of a
noncommutative K\"ahler structure is introduced. In the quantum homogeneous
space case many of the fundamental results of classical K\"ahler geometry are
shown to follow from the existence of such a structure, allowing for the
definition of noncommutative Lefschetz, Hodge, K\"ahler-Dirac, and Laplace
operators. Quantum projective space, endowed with its Heckenberger-Kolb
calculus, is taken as the motivating example. The general theory is then used
to show that the calculus has cohomology groups of at least classical
dimension.


title:
On a joint $(m, (q_1, ..., q_d))$-partial isometries and a joint
  $m$-invertible $d$-tuple of operators on a Hilbert space

abstract:
  The aim of the present paper is, firstly we study the concepts of (m, (q_1,
..., q_d))- partial isometries on a Hilbert space, secondly, we introduce the
notion of m- invertibility of tuples of operators as a natural generalization
of the m-invertibility in single variable operators.


title: A Single Model Explains both Visual and Auditory Precortical Coding

abstract:
  Precortical neural systems encode information collected by the senses, but
the driving principles of the encoding used have remained a subject of debate.
We present a model of retinal coding that is based on three constraints:
information preservation, minimization of the neural wiring, and response
equalization. The resulting novel version of sparse principal components
analysis successfully captures a number of known characteristics of the retinal
coding system, such as center-surround receptive fields, color opponency
channels, and spatiotemporal responses that correspond to magnocellular and
parvocellular pathways. Furthermore, when trained on auditory data, the same
model learns receptive fields well fit by gammatone filters, commonly used to
model precortical auditory coding. This suggests that efficient coding may be a
unifying principle of precortical encoding across modalities.


title:
Correspondence between phasor transforms and frequency response function
  in RLC circuits

abstract:
  The analysis of RLC circuits is usually made by considering phasor transforms
of sinusoidal signals (characterized by constant amplitude, period and phase)
that allow the calculation of the AC steady state of RLC circuits by solving
simple algebraic equations. In this paper I try to show that phasor
representation of RLC circuits is analogue to consider the frequency response
function (commonly designated by FRF) of the total impedance of the circuit. In
this way I derive accurate expressions for the resonance and anti-resonance
frequencies and their corresponding values of impedances of the parallel and
series RLC circuits respectively, notwithstanding the presence of damping
effects.


title: Dragons and Kasha

abstract:
  Kasha-eating dragons introduce advanced mathematics. The goal of this paper
is twofold: to entertain people who know advanced mathematics and inspire
people who don't.


title: The physical principles underpinning self-organization in plants

abstract:
  Based on laboratory based growth of plant-like structures from inorganic
materials, we present new theory for the emergence of plant structure at a
range of scales dictated by levels of ionization (charge density), which can be
traced directly back to proteins transcribed from genetic code and their
interaction with external sources of charge (such as CO2) in real plants.
Beyond a critical percolation threshold, individual charge induced quantum
poten- tials (driven by dissipative systems) merge to form a complex,
interconnected geometric web, creating macroscopic quantum potentials, which
lead to the emergence of macroscopic quantum processes. The assembly of
molecules into larger, ordered structures operates within these charge-induced
coherent bosonic fields, acting as a structuring force in competition with
exterior potentials. Within these processes many of the phenomena associated
with standard quantum theory are recovered, including quantization,
non-dissipation, self-organization, confinement, structuration conditioned by
the environment, environmental fluctuations leading to macroscopic quantum
decoherence and evolutionary time described by a time dependent
Schrodinger-like equation, which describes models of bifurcation and
duplication. The work provides a strong case for the existence of
quintessence-like behaviour, with macroscopic quantum potentials and associated
forces having their equivalence in standard quantum mechanics and gravitational
forces in general relativity. The theory offers new insight into evolutionary
processes in structural biology, with selection at any point in time, being
made from a wide range of spontaneously emerging potential structures
(dependent on conditions), which offer advantage for a specific organism. This
is valid for both the emergence of structures from a prebiotic medium and the
wide range of different plant structures we see today.


title: PeV-Scale Dark Matter as a Thermal Relic of a Decoupled Sector

abstract:
  In this letter, we consider a class of scenarios in which the dark matter is
part of a heavy hidden sector that is thermally decoupled from the Standard
Model in the early universe. The dark matter freezes-out by annihilating to a
lighter, metastable state, whose subsequent abundance can naturally come to
dominate the energy density of the universe. When this state decays, it reheats
the visible sector and dilutes all relic abundances, thereby allowing the dark
matter to be orders of magnitude heavier than the weak scale. For concreteness,
we consider a simple realization with a Dirac fermion dark matter candidate
coupled to a massive gauge boson that decays to the Standard Model through its
kinetic mixing with hypercharge. We identify viable parameter space in which
the dark matter can be as heavy as ~1-100 PeV without being overproduced in the
early universe.


title: Separating Galaxies from the Cluster Dark Matter Halo in Abell 611

abstract:
  We investigate the mass content of galaxies in the core of the galaxy cluster
Abell 611. We perform a strong lensing analysis of the cluster core and use
velocity dispersion measurements for individual cluster members as additional
constraints. Despite the small number of multiply-imaged systems and cluster
members with central velocity dispersions available in the core of A611, the
addition of velocity dispersion measurements leads to tighter constraints on
the mass associated with the galaxy component, and as a result, on the mass
associated with the dark matter halo. Without the spectroscopic velocity
dispersions, we would overestimate the mass of the galaxy component by a factor
of $\sim1.5$, or, equivalently, we would underestimate the mass of the cluster
dark halo by $\sim5\%$. We perform an additional lensing analysis using surface
brightness (SB) reconstruction of the tangential giant arc. This approach
improves the constraints on the mass parameters of the 5 galaxies close to the
arc by up to a factor $\sim10$. The galaxy velocity dispersions resulting from
the SB analysis are consistent at the 1$\sigma$ confidence level with the
spectroscopic measurements and with the prediction from the simple pointlike
analysis. In contrast the truncation radii for 2-3 galaxies depart
significantly from the galaxy scaling relation and suggest differences in the
stripping history from galaxy to galaxy.


title:
Localization and broadband follow-up of the gravitational-wave transient
  GW150914

abstract:
  A gravitational-wave (GW) transient was identified in data recorded by the
Advanced Laser Interferometer Gravitational-wave Observatory (LIGO) detectors
on 2015 September 14. The event, initially designated G184098 and later given
the name GW150914, is described in detail elsewhere. By prior arrangement,
preliminary estimates of the time, significance, and sky location of the event
were shared with 63 teams of observers covering radio, optical, near-infrared,
X-ray, and gamma-ray wavelengths with ground- and space-based facilities. In
this Letter we describe the low-latency analysis of the GW data and present the
sky localization of the first observed compact binary merger. We summarize the
follow-up observations reported by 25 teams via private Gamma-ray Coordinates
Network circulars, giving an overview of the participating facilities, the GW
sky localization coverage, the timeline and depth of the observations. As this
event turned out to be a binary black hole merger, there is little expectation
of a detectable electromagnetic (EM) signature. Nevertheless, this first
broadband campaign to search for a counterpart of an Advanced LIGO source
represents a milestone and highlights the broad capabilities of the transient
astronomy community and the observing strategies that have been developed to
pursue neutron star binary merger events. Detailed investigations of the EM
data and results of the EM follow-up campaign are being disseminated in papers
by the individual teams.


title:
Shape Dependence of Holographic Renyi Entropy in Conformal Field
  Theories

abstract:
  We develop a framework for studying the well-known universal term in the
Renyi entropy for an arbitrary entangling region in four-dimensional conformal
field theories that are holographically dual to gravitational theories. The
shape dependence of the Renyi entropy $S_n$ is described by two coefficients:
$f_b(n)$ for traceless extrinsic curvature deformations and $f_c(n)$ for Weyl
tensor deformations. We provide the first calculation of the coefficient
$f_b(n)$ in interacting theories by relating it to the stress tensor one-point
function in a deformed hyperboloid background. The latter is then determined by
a straightforward holographic calculation. Our results show that a previous
conjecture $f_b(n) = f_c(n)$, motivated by surprising evidence from a variety
of free field theories and studies of conical defects, fails holographically.

categories: hep-th cond-mat.stat-mech gr-qc quant-ph


title: A new look at the theory uncertainty of epsilon_K

abstract:
  The observable epsilon_K is sensitive to flavor violation at some of the
highest scales. While its experimental uncertainty is at the half percent
level, the theoretical one is in the ballpark of 15%. We explore the nontrivial
dependence of the theory prediction and uncertainty on various conventions,
like the phase of the kaon fields. In particular, we show how such a rephasing
allows to make the short-distance contribution of the box diagram with two
charm quarks, eta_cc, purely real. Our results allow to slightly reduce the
total theoretical uncertainty of epsilon_K, while increasing the relative
impact of the imaginary part of the long distance contribution, underlining the
need to compute it reliably. We also give updated bounds on the new physics
operators that contribute to epsilon_K.


title: Protostars: Forges of cosmic rays?

abstract:
  Galactic cosmic rays (CR) are particles presumably accelerated in supernova
remnant shocks that propagate in the interstellar medium up to the densest
parts of molecular clouds, losing energy and their ionisation efficiency
because of the presence of magnetic fields and collisions with molecular
hydrogen. Recent observations hint at high levels of ionisation and at the
presence of synchrotron emission in protostellar systems, which leads to an
apparent contradiction. We want to explain the origin of these CRs accelerated
within young protostars as suggested by observations. Our modelling consists of
a set of conditions that has to be satisfied in order to have an efficient CR
acceleration through diffusive shock acceleration. We analyse three main
acceleration sites, then we follow the propagation of these particles through
the protostellar system up to the hot spot region. We find that jet shocks can
be strong accelerators of CR protons, which can be boosted up to relativistic
energies. Other promising acceleration sites are protostellar surfaces, where
shocks caused by impacting material during the collapse phase are strong enough
to accelerate CR protons. In contrast, accretion flow shocks are too weak to
efficiently accelerate CRs. Though CR electrons are weakly accelerated, they
can gain a strong boost to relativistic energies through re-acceleration in
successive shocks. We suggest a mechanism able to accelerate both CR protons
and electrons through the diffusive shock acceleration mechanism, which can be
used to explain the high ionisation rate and the synchrotron emission observed
towards protostellar sources. The existence of an internal source of energetic
particles can have a strong and unforeseen impact on the ionisation of the
protostellar disc, on the star and planet formation processes, and on the
formation of pre-biotic molecules.


title:
Interaction Cross Sections and Survival Rates for Proposed Solar System
  Member Planet Nine

abstract:
  Motivated by the report of a possible new planetary member of the Solar
System, this work calculates cross sections for interactions between passing
stars and this proposed Planet Nine. Evidence for the new planet is provided by
the orbital alignment of Kuiper Belt objects, and other Solar System
properties, which suggest a Neptune-mass object on an eccentric orbit with
semimajor axis $a_9\approx400-1500$ AU. With such a wide orbit, Planet Nine has
a large interaction cross section, and is susceptible to disruption by passing
stars. Using a large ensemble of numerical simulations (several million), and
Monte Carlo sampling, we calculate the cross sections for different classes of
orbit-altering events: [A] scattering the planet into its proposed orbit from a
smaller orbit, [B] ejecting it from the Solar System from its current orbit,
[C] capturing the planet from another system, and [D] capturing a free-floating
planet. Results are presented for a range of orbital elements with planetary
mass $m_9=10M_{earth}$. Removing Planet Nine from the Solar System is the most
likely outcome. Specifically, we obtain ejection cross sections
$\sigma_{int}\sim5\times10^6$ AU$^2$ ($5\times10^4$ AU$^2$) for environments
corresponding to the birth cluster (field). With these cross sections, Planet
Nine is likely to be ejected if the Sun resides within its birth cluster longer
than $\Delta{t} \gtrsim 100$ Myr. The probability of ejecting Planet Nine due
to passing field stars is $\lesssim 3\%$ over the age of the Sun. Probabilities
for producing the inferred Planet Nine orbit are low $(\lesssim 5\%)$.


title:
SOMBI: Bayesian identification of parameter relations in unstructured
  cosmological data

abstract:
  This work describes the implementation and application of a correlation
determination method based on Self Organizing Maps and Bayesian Inference
(SOMBI). SOMBI aims to automatically identify relations between different
observed parameters in unstructured cosmological or astrophysical surveys by
automatically identifying data clusters in high-dimensional datasets via the
Self Organizing Map neural network algorithm. Parameter relations are then
revealed by means of a Bayesian inference within respective identified data
clusters. Specifically such relations are assumed to be parametrized as a
polynomial of unknown order. The Bayesian approach results in a posterior
probability distribution function for respective polynomial coefficients. To
decide which polynomial order suffices to describe correlation structures in
data, we include a method for model selection, the Bayesian Information
Criterion, to the analysis. The performance of the SOMBI algorithm is tested
with mock data. As illustration we also provide applications of our method to
cosmological data. In particular, we present results of a correlation analysis
between galaxy and AGN properties provided by the SDSS catalog with the cosmic
large-scale-structure (LSS). The results indicate that the combined galaxy and
LSS dataset indeed is clustered into several sub-samples of data with different
average properties (for example different stellar masses or web-type
classifications). The majority of data clusters appear to have a similar
correlation structure between galaxy properties and the LSS. In particular we
revealed a positive and linear dependency between the stellar mass, the
absolute magnitude and the color of a galaxy with the corresponding cosmic
density field. A remaining subset of data shows inverted correlations, which
might be an artifact of non-linear redshift distortions.


title: Discovery of a massive supercluster system at $z \sim 0.47$

abstract:
  Superclusters are the largest relatively isolated systems in the cosmic web.
Using the SDSS BOSS survey we search for the largest superclusters in the
redshift range $0.43<z<0.71$.
  We generate a luminosity-density field smoothed over $8 h^{-1}\mathrm{Mpc}$
to detect the large-scale over-density regions. Each individual over-density
region is defined as single supercluster in the survey. We define the
superclusters in the way that they are comparable with the superclusters found
in the SDSS main survey.
  We found a system we call the BOSS Great Wall (BGW), which consists of two
walls with diameters 186 and 173 $h^{-1}$Mpc, and two other major superclusters
with diameters of 64 and 91 $h^{-1}$Mpc. As a whole, this system consists of
830 galaxies with the mean redshift 0.47. We estimate the total mass to be
approximately $2\times10^{17}h^{-1}M_\odot$. The morphology of the
superclusters in the BGW system is similar to the morphology of the
superclusters in the Sloan Great Wall region.
  The BGW is one of the most extended and massive system of superclusters yet
found in the Universe.


title: Higher-Spin Theory of the Magnetorotons

abstract:
  Fractional quantum Hall liquids exhibit a rich set of excitations, the
lowest-energy of which are the magnetorotons with dispersion minima at a finite
momentum. We propose a theory of the magnetorotons on the quantum Hall plateaux
near half filling, namely, at filling fractions $\nu=N/(2N+1)$ at large $N$.
The theory involves an infinite number of bosonic fields arising from
bosonizing the fluctuations of the shape of the composite Fermi surface. At
zero momentum there are $O(N)$ neutral excitations, each carrying a
well-defined spin that runs integer values $2,3,\ldots$. The mixing of modes at
nonzero momentum $q$ leads to the characteristic bending down of the lowest
excitation and the appearance of the magnetoroton minima. A purely algebraic
argument shows that the magnetoroton minima are located at
$q\ell_B=z_i/(2N+1)$, where $\ell_B$ is the magnetic length and $z_i$ are the
zeros of the Bessel function $J_1$, independent of the microscopic details. We
argue that these minima are universal features of any two-dimensional Fermi
surface coupled to a gauge field in a small background magnetic field.


title: Morphological Classification of Local Luminous Infrared Galaxies

abstract:
  We present an analysis of the morphological classification of 89 luminous
infrared galaxies (LIRGs) from the Great Observatories All-sky LIRG Survey
(GOALS) sample using non-parametric coefficients and compare their morphology
as a function of wavelength. We rely on images obtained in the optical (B- and
I-band) as well as in the infrared (H-band and 5.8$\mu$m). Our classification
is based on the calculation of $Gini$ and the second order of light ($M_{20}$)
non-parametric coefficients which we explore as a function of stellar mass
($M_\star$), infrared luminosity ($L_{IR}$) and star formation rate (SFR). We
investigate the relation between $M_{20}$, the specific SFR (sSFR) and the dust
temperature ($T_{dust}$) in our galaxy sample. We find that $M_{20}$ is a
better morphological tracer than $Gini$, as it allows to distinguish systems
formed by double systems from isolated and post-merger LIRGs. The
multi-wavelength analysis allows us to identify a region in the $Gini$-$M_{20}$
parameter space where ongoing mergers reside, regardless of the band used to
calculate the coefficients. In particular when measured in the H-band, this
region can be used to identify ongoing mergers, with a minimal contamination
from LIRGs in other stages. We also find that while the sSFR is positively
correlated with $M_{20}$ when measured in the mid-infrared, i.e. star-bursting
galaxies show more compact emission, it is anti-correlated with the B-band
based $M_{20}$. We interpret this as the spatial decoupling between obscured
and un-obscured star formation, whereby the ultraviolet/optical size of a LIRGs
experience an intense dust enshrouded central starburst is larger than in the
one in the mid-infrared since the contrast between the nuclear to the extended
disk emission is smaller in the mid-infrared. This has important implications
for high redshift surveys of dusty sources. [abridged]


title:
Extending Fermi-LAT and H.E.S.S. Limits on Gamma-ray Lines from Dark
  Matter Annihilation

abstract:
  Gamma-ray lines from dark matter annihilation ($\chi\chi\to \gamma X$, where
$X=\gamma,h,Z$) are always accompanied, at lower energies, by a continuum
gamma-ray spectrum stemming both from radiative corrections ($X=\gamma$) and
from the decay debris of the second particle possibly present in the final
state ($X=h,Z$). This model-independent gamma-ray emission can be exploited to
derive novel limits on gamma-ray lines that do not rely on the line-feature.
Although such limits are not expected to be as stringent, they can be used to
probe the existence of $\gamma$-ray lines for dark matter masses beyond the
largest energies accessible to current telescopes. Here, we use continuous
gamma-ray searches from Fermi-LAT observations of Milky Way dwarf spheroidal
galaxies and from H.E.S.S. observations of the Galactic Halo to extend the
limits on the annihilation cross sections into monochromatic photons to dark
matter masses well beyond $500$ GeV (Fermi-LAT) and $20$ TeV (H.E.S.S.). In
this large mass regime, our results provide the first constraints on
$\gamma$-ray lines from dark matter annihilation.


title: Finite presentability and isomorphism of Cayley graphs of monoids

abstract:
  Two finitely generated monoids are constructed, one finitely presented the
other not, whose (directed, unlabelled) Cayley graphs are isomorphic.


title: Improving lognormal models for cosmological fields

abstract:
  It is common practice in cosmology to model large-scale structure observables
as lognormal random fields, and this approach has been successfully applied in
the past to the matter density and weak lensing convergence fields separately.
We argue that this approach has fundamental limitations which prevent its use
for jointly modelling these two fields since the lognormal distribution's shape
can prevent certain correlations to be attainable. Given the need of ongoing
and future large-scale structure surveys for fast joint simulations of
clustering and weak lensing, we propose two ways of overcoming these
limitations. The first approach slightly distorts the power spectra of the
fields using one of two algorithms that minimises either the absolute or the
fractional distortions. The second one is by obtaining more accurate
convergence marginal distributions, for which we provide a fitting function, by
integrating the lognormal density along the line of sight. The latter approach
also provides a way to determine directly from theory the skewness of the
convergence distribution and, therefore, the parameters for a lognormal fit. We
present the public code Full-sky Lognormal Astro-fields Simulation Kit (FLASK)
which can make tomographic realisations on the sphere of an arbitrary number of
correlated lognormal or Gaussian random fields by applying either of the two
proposed solutions, and show that it can create joint simulations of clustering
and lensing with sub-per-cent accuracy over relevant angular scales and
redshift ranges.


title: Algebraic Presentations of Dependent Type Theories

abstract:
  In this paper, we propose an abstract definition of dependent type theories
as essentially algebraic theories. One of the main advantages of this
definition is its composability: simple theories can be combined into more
complex ones, and different properties of the resulting theory may be deduced
from properties of the basic ones. We define a category of algebraic dependent
type theories which allows us not only to combine theories but also to consider
equivalences between them. We also study models of such theories and show that
one can think of them as contextual categories with additional structure.


title: Neutral gas outflows in nearby [U]LIRGs via optical NaD feature

abstract:
  We studied the properties of the neutral gas in a sample of 38 local
[U]LIRGs, which mainly covers the less explored LIRG luminosity range. This
study is based on the analysis of the spatially integrated and spatially
resolved spectra of the NaD feature obtained with the VIMOS/VLT-IFS. Analyzing
spatially integrated spectra, we find that the contribution of stars to the
observed NaD-EWs is generally small (<35%), and therefore this feature is
dominated by ISM absorption. After subtracting the stellar contribution, we
find that the pure-ISM integrated spectra generally show blueshifted NaD
profiles, indicating neutral gas outflow velocities V in the range 65-260 km/s.
Excluding galaxies with AGNs, V shows a dependency with the SFR of the type V
\propto SFR^0.15 (in rather good agreement with previous results). The
spatially resolved analysis was performed for 40 galaxies, 22 of which have
neutral gas velocity fields dominated by noncircular motions with signatures of
cone-like winds. However, a modest number of targets (11/40) show disk
rotation. We found that the wind masses are in the range (0.4-7.5)x10^8 Msun,
reaching up to 3% of the dynamical mass of the host. The mass rates are
typically only 0.2-0.4 times the SFR indicating that, the mass loss is too
small to slow down the SF significantly. In the majority of cases, the velocity
of the outflowing gas is not sufficient to escape the host potential well and,
therefore, most of the gas rains back into the disk. On average V/v(esc) is
higher in less massive galaxies, confirming that the galaxy mass has a primary
role in shaping the recycling of gas and metals. The comparison between the
wind power and kinetic power of the starburst associated with SNe indicates
that the starburst could drive the outflows in nearly all the [U]LIRGs
galaxies, as the wind power is generally lower than 20% of the kinetic power
supplied by the starburst.


title: Minimal Models of Loop-Induced Higgs Lepton Flavor Violation

abstract:
  The LHC has recently reported a slight excess in the $h\rightarrow \tau \mu$
channel. If this lepton flavor violating (LFV) decay is confirmed, an extension
of the Standard Model (SM) will be required to explain it. In this paper we
investigate two different possibilities to accommodate such a LFV process: the
first scenario is based on flavor off-diagonal $A$-terms in the Minimal
Supersymmetric Standard Model (MSSM), and the second is a model where the Higgs
couples to new vectorlike fermions that couple to the SM leptons through a LFV
four fermion interaction. In the supersymmetric model, we find that the sizes
of the $A$-terms needed to accommodate the $h\rightarrow \tau\mu$ excess are in
conflict with charge- and color-breaking vacuum constraints. In the second
model, the excess can be successfully explained while satisfying all other
flavor constrains, with order one couplings, vectorlike fermion masses as low
as 15 TeV, and a UV scale higher than 35 TeV.


title:
Occupancy Estimation in Smart Buildings using Audio-Processing
  Techniques

abstract:
  In the past few years, several case studies have illustrated that the use of
occupancy information in buildings leads to energy-efficient and low-cost HVAC
operation. The widely presented techniques for occupancy estimation include
temperature, humidity, CO2 concentration, image camera, motion sensor and
passive infrared (PIR) sensor. So far little studies have been reported in
literature to utilize audio and speech processing as indoor occupancy
prediction technique. With rapid advances of audio and speech processing
technologies, nowadays it is more feasible and attractive to integrate
audio-based signal processing component into smart buildings. In this work, we
propose to utilize audio processing techniques (i.e., speaker recognition and
background audio energy estimation) to estimate room occupancy (i.e., the
number of people inside a room). Theoretical analysis and simulation results
demonstrate the accuracy and effectiveness of this proposed occupancy
estimation technique. Based on the occupancy estimation, smart buildings will
adjust the thermostat setups and HVAC operations, thus, achieving greater
quality of service and drastic cost savings.


title: A joint routing and speed optimization problem

abstract:
  Fuel cost contributes to a significant portion of operating cost in cargo
transportation. Though classic routing models usually treat fuel cost as input
data, fuel consumption heavily depends on the travel speed, which has led to
the study of optimizing speeds over a given fixed route. In this paper, we
propose a joint routing and speed optimization problem to minimize the total
cost, which includes the fuel consumption cost. The only assumption made on the
dependence between the fuel cost and travel speed is that it is a strictly
convex differentiable function. This problem is very challenging, with
medium-sized instances already difficult for a general mixed-integer convex
optimization solver. We propose a novel set partitioning formulation and a
branch-cut-and-price algorithm to solve this problem. Our algorithm clearly
outperforms the off-the-shelf optimization solver, and is able to solve some
benchmark instances to optimality for the first time.


title:
Estimating Distribution Grid Topologies: A Graphical Learning based
  Approach

abstract:
  Distribution grids represent the final tier in electric networks consisting
of medium and low voltage lines that connect the distribution substations to
the end-users. Traditionally, distribution networks have been operated in a
radial topology that may be changed from time to time. Due to absence of a
significant number of real-time line monitoring devices in the distribution
grid, estimation of the topology is a problem critical for its observability
and control. This paper develops a novel graphical learning based approach to
estimate the radial operational grid structure using voltage measurements
collected from the grid loads. The learning algorithm is based on conditional
independence tests for continuous variables over chordal graphs and has wide
applicability. It is proven that the scheme can be used for several power flow
laws (DC or AC approximations) and more importantly is independent of the
specific probability distribution controlling individual bus power usage. The
complexity of the algorithm is discussed and its performance is demonstrated by
simulations on distribution test cases.


title:
Patch-Ordering as a Regularization for Inverse Problems in Image
  Processing

abstract:
  Recent work in image processing suggests that operating on (overlapping)
patches in an image may lead to state-of-the-art results. This has been
demonstrated for a variety of problems including denoising, inpainting,
deblurring, and super-resolution. The work reported in [1,2] takes an extra
step forward by showing that ordering these patches to form an approximate
shortest path can be leveraged for better processing. The core idea is to apply
a simple filter on the resulting 1D smoothed signal obtained after the
patch-permutation. This idea has been also explored in combination with a
wavelet pyramid, leading eventually to a sophisticated and highly effective
regularizer for inverse problems in imaging. In this work we further study the
patch-permutation concept, and harness it to propose a new simple yet effective
regularization for image restoration problems. Our approach builds on the
classic Maximum A'posteriori probability (MAP), with a penalty function
consisting of a regular log-likelihood term and a novel permutation-based
regularization term. Using a plain 1D Laplacian, the proposed regularization
forces robust smoothness (L1) on the permuted pixels. Since the permutation
originates from patch-ordering, we propose to accumulate the smoothness terms
over all the patches' pixels. Furthermore, we take into account the found
distances between adjacent patches in the ordering, by weighting the Laplacian
outcome. We demonstrate the proposed scheme on a diverse set of problems: (i)
severe Poisson image denoising, (ii) Gaussian image denoising, (iii) image
deblurring, and (iv) single image super-resolution. In all these cases, we use
recent methods that handle these problems as initialization to our scheme. This
is followed by an L-BFGS optimization of the above-described penalty function,
leading to state-of-the-art results, and especially so for highly ill-posed
cases.


title:
High-precision timing of 42 millisecond pulsars with the European Pulsar
  Timing Array

abstract:
  We report on the high-precision timing of 42 radio millisecond pulsars (MSPs)
observed by the European Pulsar Timing Array (EPTA). This EPTA Data Release 1.0
extends up to mid-2014 and baselines range from 7-18 years. It forms the basis
for the stochastic gravitational-wave background, anisotropic background, and
continuous-wave limits recently presented by the EPTA elsewhere. The Bayesian
timing analysis performed with TempoNest yields the detection of several new
parameters: seven parallaxes, nine proper motions and, in the case of six
binary pulsars, an apparent change of the semi-major axis. We find the NE2001
Galactic electron density model to be a better match to our parallax distances
(after correction from the Lutz-Kelker bias) than the M2 and M3 models by
Schnitzeler (2012). However, we measure an average uncertainty of 80\%
(fractional) for NE2001, three times larger than what is typically assumed in
the literature. We revisit the transverse velocity distribution for a set of 19
isolated and 57 binary MSPs and find no statistical difference between these
two populations. We detect Shapiro delay in the timing residuals of PSRs
J1600$-$3053 and J1918$-$0642, implying pulsar and companion masses
$m_p=1.22_{-0.35}^{+0.5} \text{M}_{\odot}$, $m_c = 0.21_{-0.04}^{+0.06}
\text{M}_{\odot }$ and $m_p=1.25_{-0.4}^{+0.6} \text{M}_{\odot}$, $m_c =
0.23_{-0.05}^{+0.07} \text{M}_{\odot }$, respectively. Finally, we use the
measurement of the orbital period derivative to set a stringent constraint on
the distance to PSRs J1012$+$5307 and J1909$-$3744, and set limits on the
longitude of ascending node through the search of the annual-orbital parallax
for PSRs J1600$-$3053 and J1909$-$3744.


title:
Geometric Flows and Perelman's Thermodynamics for Black Ellipsoids in
  $R^2$ and Einstein Gravity Theories

abstract:
  We study geometric relativistic flow and Ricci soliton equations which (for
respective nonholonomic constraints and self-similarity conditions) are
equivalent to the gravitational field equations of $R^2$ gravity and/or to the
Einstein equations with scalar field in general relativity, GR. Perelman's
functionals are generalized for modified gravity theories, MGTs, which allows
to formulate an analogous statistical thermodynamics for geometric flows and
Ricci solitons. There are constructed and analyzed generic off-diagonal black
ellipsoid, black hole and solitonic exact solutions in MGTs and GR encoding
geometric flow evolution scenarios and nonlinear parametric interactions. Such
new classes of solutions in MGTs can be with polarized and/or running
constants, nonholonomically deformed horizons and/or imbedded self-consistently
into solitonic backgrounds. They exist also in GR as generic off-diagonal
vacuum configurations with effective cosmological constant and/or mimicking
effective scalar field interactions. Finally, we compute Perelman's energy and
entropy for black ellipsoids and evolution solitons in $R^2$ gravity.


title:
Non-trivial static, spherically symmetric vacuum solution in a
  non-conservative theory of gravity

abstract:
  We analyse the vacuum static spherically symmetric space-time for a specific
class of non-conservative theories of gravity based on the Rastall's theory. We
obtain a new vacuum solution which has the same structure as the
Schwarzschild-de Sitter solution in the General Relativity theory obtained with
a cosmological constant playing the r\^ole of source. We further discuss the
structure (in particular, the coupling to matter fields) and some cosmological
aspects of the underline non-conservative theory


title:
Gravitational collapse of dissipative fluid as a source of gravitational
  waves

abstract:
  Gravitational collapse of cylindrical anisotropic fluid has been considered
in analogy with the work of Misner and Sharp. Using Darmois matching
conditions, the interior cylindrical dissipative fluid (in the form of shear
viscosity and heat flux )is matched to an exterior vacuum Einstein--Rosen
space-time. It is found that on the bounding 3-surface the radial pressure of
the anisotropic perfect fluid is linearly related to the shear viscosity and
the heat flux of the dissipative fluid on the boundary. This non-zero radial
pressure on the bounding surface may be considered as the source of
gravitational waves outside the collapsing matter distribution.


title:
On the computational complexity of minimum-concave-cost flow in a
  two-dimensional grid

abstract:
  We study the minimum-concave-cost flow problem on a two-dimensional grid. We
characterize the computational complexity of this problem based on the number
of rows and columns of the grid, the number of different capacities over all
arcs, and the location of sources and sinks. The concave cost over each arc is
assumed to be evaluated through an oracle machine, i.e., the oracle machine
returns the cost over an arc in a single computational step, given the flow
value and the arc index. We propose an algorithm whose running time is
polynomial in the number of columns of the grid, for the following cases: (1)
the grid has a constant number of rows, a constant number of different
capacities over all arcs, and sources and sinks in at most two rows; (2) the
grid has two rows and a constant number of different capacities over all arcs
connecting rows; (3) the grid has a constant number of rows and all sources in
one row, with infinite capacity over each arc. These are presumably the most
general polynomially solvable cases, since we show the problem becomes NP-hard
when any condition in these cases is removed. Our results apply to abundant
variants and generalizations of the dynamic lot sizing model, and answer
several questions raised in serial supply chain optimization.


title: The Relationship Between Inertial and Gravitational Mass

abstract:
  I will argue that the inertial mass is greater than the gravitational mass
for all objects which are held together primarily by gravitational forces.
Thus, for celestial objects, like planets, stars and galaxies, their inertial
mass is greater than their gravitational mass. The analysis used to arrive at
this conclusion shows that there should, in principle, exist classical objects
with non-zero inertial mass and vanishing gravitational mass. Implications for
Quantum Gravity and Quantum Cosmology, are briefly discussed.


title: Evaluating Stochastic Methods in Power System Operations with Wind Power

abstract:
  Wind power is playing an increasingly important role in electricity markets.
However, it's inherent variability and uncertainty cause operational challenges
and costs as more operating reserves are needed to maintain system reliability.
Several operational strategies have been proposed to address these challenges,
including advanced probabilistic wind forecasting techniques, dynamic operating
reserves, and various unit commitment (UC) and economic dispatch (ED)
strategies under uncertainty. This paper presents a consistent framework to
evaluate different operational strategies in power system operations with
renewable energy. We use conditional Kernel Density Estimation (KDE) for
probabilistic wind power forecasting. Forecast scenarios are generated
considering spatio-temporal correlations, and further reduced to lower the
computational burden. Scenario-based stochastic programming with different
decomposition techniques and interval optimization are tested to examine
economic, reliability, and computational performance compared to deterministic
UC/ED benchmarks. We present numerical results for a modified IEEE-118 bus
system with realistic system load and wind data.


title:
Rotationally Induced Surface Slope-Instabilities and the Activation of
  CO2 Activity on Comet 103P/Hartley 2

abstract:
  Comet 103P/Hartley 2 has diurnally controlled, CO2-driven activity on the tip
of the small lobe of its bilobate nucleus. Such activity is unique among the
comet nuclei visited by spacecraft, and suggests that CO2 ice is very near the
surface, which is inconsistent with our expectations of an object that
thermophysically evolved for ~45 million years prior to entering the Jupiter
Family of comets. Here we explain this pattern of activity by showing that a
very plausible recent episode of rapid rotation (rotation period of ~11 [10-13]
hours) would have induced avalanches in Hartley 2's currently active regions
that excavated down to CO2-rich ices and activated the small lobe of the
nucleus. At Hartley 2's current rate of spindown about its principal axis, the
nucleus would have been spinning fast enough to induce avalanches ~3-4 orbits
prior to the DIXI flyby (~1984-1991). This coincides with Hartley 2's discovery
in 1986, and implies that the initiation of CO2 activity facilitated the
comet's discovery. During the avalanches, the sliding material would either be
lofted off the surface by gas activity, or possibly gained enough momentum
moving downhill (toward the tip of the small lobe) to slide off the nucleus.
Much of this material would have failed to reach escape velocity, and would
reimpact the nucleus, forming debris deposits. The similar size frequency
distribution of the mounds observed on the surface of Hartley 2 and chunks of
material in its inner coma suggest that the 20-40 meter mounds observed by the
DIXI mission on the surface of Hartley 2 are potentially these fallback debris
deposits. As the nucleus spun down from a rotation period of ~11 hours to 18.34
hours at the time of the DIXI flyby, the location of potential minima, where
materials preferentially settle, migrated about the surface, allowing us to
place relative ages on most of the imaged terrains of the nucleus.


title: Analysing Survey Propagation Guided Decimation on Random Formulas

abstract:
  Let $\varPhi$ be a uniformly distributed random $k$-SAT formula with $n$
variables and $m$ clauses. For clauses/variables ratio $m/n \leq
r_{k\text{-SAT}} \sim 2^k\ln2$ the formula $\varPhi$ is satisfiable with high
probability. However, no efficient algorithm is known to provably find a
satisfying assignment beyond $m/n \sim 2k \ln(k)/k$ with a non-vanishing
probability. Non-rigorous statistical mechanics work on $k$-CNF led to the
development of a new efficient "message passing algorithm" called \emph{Survey
Propagation Guided Decimation} [M\'ezard et al., Science 2002]. Experiments
conducted for $k=3,4,5$ suggest that the algorithm finds satisfying assignments
close to $r_{k\text{-SAT}}$. However, in the present paper we prove that the
basic version of Survey Propagation Guided Decimation fails to solve random
$k$-SAT formulas efficiently already for $m/n=2^k(1+\varepsilon_k)\ln(k)/k$
with $\lim_{k\to\infty}\varepsilon_k= 0$ almost a factor $k$ below
$r_{k\text{-SAT}}$.


title: Homogenization of a mean field game system in the small noise limit

abstract:
  This paper concerns the simultaneous effect of homogenization and of the
small noise limit for a $2^{\textrm {nd}}$ order mean field games (MFG) system
with local coupling and quadratic Hamiltonian. We show under some additional
assumptions that the solutions of our system converge to a solution of an
effective $1^{\textrm {st}}$ order system whose effective operators are defined
through a cell problem which is a $2^{\textrm {nd}}$ order system of ergodic
MFG type. We provide several properties of the effective operators and we show
that in general the effective system looses the MFG structure.


title:
Theoretical Properties and Practical Performance of Fully Robust
  One-Sided Cross-Validation

abstract:
  Fully robust OSCV is a modification of the OSCV method that produces
consistent bandwidth in the cases of smooth and nonsmooth regression functions.
The current implementation of the method uses the kernel $H_I$ that is almost
indistinguishable from the Gaussian kernel on the interval $[-4,4]$, but has
negative tails. The theoretical properties and practical performances of the
$H_I$- and $\phi$-based OSCV versions are compared. The kernel $H_I$ tends to
produce too low bandwidths in the smooth case. The $H_I$-based OSCV curves are
shown to have wiggles appearing in the neighborhood of zero. The kernel $H_I$
uncovers sensitivity of the OSCV method to a tiny modification of the kernel
used for the cross-validation purposes. The recently found robust bimodal
kernels tend to produce OSCV curves with multiple local minima. The problem of
finding a robust unimodal nonnegative kernel remains open.


title: TeV Gamma-ray Observations of The Galactic Center Ridge By VERITAS

abstract:
  The Galactic Center Ridge has been observed extensively in the past by both
GeV and TeV gamma-ray instruments revealing a wealth of structure, including a
diffuse component as well as the point sources G0.9+0.1 (a composite supernova
remnant) and Sgr A* (believed to be associated with the supermassive black hole
located at the center of our Galaxy). Previous very high energy (VHE) gamma-ray
observations with the H.E.S.S. experiment have also detected an extended TeV
gamma-ray component along the Galactic plane in the >300 GeV gamma-ray regime.
Here we report on observations of the Galactic Center Ridge from 2010-2014 by
the VERITAS telescope array in the >2 TeV energy range. From these observations
we 1.) provide improved measurements of the differential energy spectrum for
Sgr A* in the >2 TeV gamma-ray regime, 2.) provide a detection in the >2 TeV
gamma-ray emission from the composite SNR G0.9+0.1 and an improved
determination of its multi-TeV gamma-ray energy spectrum, 3.) report on the
detection of VER J1746-289, a localized enhancement of >2 TeV gamma-ray
emission along the Galactic plane.


title: Self-synchronization of Kerr-nonlinear Optical Parametric Oscillators

abstract:
  We introduce a new, reduced nonlinear oscillator model governing the
spontaneous creation of sharp pulses in a damped, driven, cubic nonlinear
Schroedinger equation. The reduced model embodies the fundamental connection
between mode synchronization and spatiotemporal pulse formation. We identify
attracting solutions corresponding to stable cavity solitons and Turing
patterns. Viewed in the optical context, our results explain the recently
reported $\pi$ and $\pi/2$ steps in the phase spectrum of microresonator-based
optical frequency combs.


title:
Using the Automata Processor for Fast Pattern Recognition in High Energy
  Physics Experiments - A Proof of Concept

abstract:
  We explore the Micron Automata Processor (AP) as a suitable commodity
technology that can address the growing computational needs of pattern
recognition in High Energy Physics (HEP) experiments. A toy detector model is
developed for which an electron track confirmation trigger based on the Micron
AP serves as a test case. Although primarily meant for high speed text-based
searches, we demonstrate a proof of concept for the use of the Micron AP in a
HEP trigger application.


title:
Two types of all-optical magnetization switching mechanisms using
  femtosecond laser pulses

abstract:
  Magnetization manipulation in the absence of an external magnetic field is a
topic of great interest, since many novel physical phenomena need to be
understood and promising new applications can be imagined. Cutting-edge
experiments have shown the capability to switch the magnetization of magnetic
thin films using ultrashort polarized laser pulses. In 2007, it was first
observed that the magnetization switching for GdFeCo alloy thin films was
helicity-dependent and later helicity-independent switching was also
demonstrated on the same material. Recently, all-optical switching has also
been discovered for a much larger variety of magnetic materials (ferrimagnetic,
ferromagnetic films and granular nanostructures), where the theoretical models
explaining the switching in GdFeCo films do not appear to apply, thus
questioning the uniqueness of the microscopic origin of all-optical switching.
Here, we show that two different all-optical switching mechanisms can be
distinguished; a "single pulse" switching and a "cumulative" switching process
whose rich microscopic origin is discussed. We demonstrate that the latter is a
two-step mechanism; a heat-driven demagnetization followed by a
helicity-dependent remagnetization. This is achieved by an all-electrical and
time-dependent investigation of the all-optical switching in ferrimagnetic and
ferromagnetic Hall crosses via the anomalous Hall effect, enabling to probe the
all-optical switching on different timescales.


title: Progress towards quantitative design principles of multicellular systems

abstract:
  Living systems, particularly multicellular systems, often seem hopelessly
complex. But recent studies have suggested that beneath this complexity, there
may be unifying quantitative principles that we are only now starting to
unravel. All cells interact with their environments and with other cells.
Communication among cells is a primary means for cells to interact with each
other. The complexity of these multicellular systems, due to the large numbers
of cells and the diversity of intracellular and intercellular interactions,
makes understanding multicellular systems a daunting task. To overcome this
challenge, we will likely need judicious simplifications and conceptual
frameworks that can reveal design principles that are shared among diverse
multicellular systems. Here we review some recent progress towards developing
such frameworks.


title:
The Energy Balance Relation for Weak solutions of the Density-Dependent
  Navier-Stokes Equations

abstract:
  We consider the incompressible inhomogeneous Navier-Stokes equations with
constant viscosity coefficient and density which is bounded and bounded away
from zero. We show that the energy balance relation for this system holds for
weak solutions if the velocity, density, and pressure belong to a range Besov
spaces of smoothness $1/3$. A density-dependent version of the classical
K\'arm\'an-Howarth-Monin relation is derived.


title:
Toward a Comprehensive Model of Snow Crystal Growth: 5. Measurements of
  Changes in Attachment Kinetics from Background Gas Interactions at -5 C

abstract:
  We present measurements of the diffusion-limited growth of ice crystals from
water vapor at a temperature of -5 C, in air at a pressure of $p_{air}=1$ bar.
Starting with thin, c-axis ice needle crystals, the subsequent growth
morphologies ranged from solid prismatic columns to hollow columns to complex
"fishbone" dendritic structures as the supersaturation was increased. We
modeled the simpler morphologies using analytical techniques together with a
cellular-automata method that yields faceted crystalline structures in
diffusion-limited growth. We found that the molecular attachment coefficient
$\alpha_{prism}$ on faceted prism surfaces in air at -5 C is substantially
lower than that measured at low background air pressure. Our data show that
increasing $p_{air}$ from 0.01 to 1 bar reduces $\alpha_{prism}$ by nearly two
orders of magnitude at this temperature. In contrast, we find that
$\alpha_{basil}$ is essentially unaffected by air pressure over this range.
These and other measurements indicate that ice surfaces near the melting point
undergo a series of complex structural and dynamical changes with temperature
that remain largely unexplained at even a qualitative level.


title: Finding a Large Submatrix of a Gaussian Random Matrix

abstract:
  We consider the problem of finding a $k\times k$ submatrix of an $n\times n$
matrix with i.i.d. standard Gaussian entries, which has a large average entry.
It was shown earlier by Bhamidi et al. that the largest average value of such a
matrix is $2\sqrt{\log n/k}$ with high probability. In the same paper an
evidence was provided that a natural greedy algorithm called Largest Average
Submatrix ($\LAS$) should produce a matrix with average entry approximately
$\sqrt{2}$ smaller.
  In this paper we show that the matrix produced by the $\LAS$ algorithm is
indeed $\sqrt{2\log n/k}$ w.h.p. Then by drawing an analogy with the problem of
finding cliques in random graphs, we propose a simple greedy algorithm which
produces a $k\times k$ matrix with asymptotically the same average value. Since
the greedy algorithm is the best known algorithm for finding cliques in random
graphs, it is tempting to believe that beating the factor $\sqrt{2}$
performance gap suffered by both algorithms might be very challenging.
Surprisingly, we show the existence of a very simple algorithm which produces a
matrix with average value $(4/3)\sqrt{2\log n/k}$.
  To get an insight into the algorithmic hardness of this problem, and
motivated by methods originating in the theory of spin glasses, we conduct the
so-called expected overlap analysis of matrices with average value
asymptotically $\alpha\sqrt{2\log n/k}$. The overlap corresponds to the number
of common rows and common columns for pairs of matrices achieving this value.
We discover numerically an intriguing phase transition at $\alpha^*\approx
1.3608..$: when $\alpha<\alpha^*$ the space of overlaps is a continuous subset
of $[0,1]^2$, whereas $\alpha=\alpha^*$ marks the onset of discontinuity, and
the model exhibits the Overlap Gap Property when $\alpha>\alpha^*$. We
conjecture that $\alpha>\alpha^*$ marks the onset of the algorithmic hardness.

categories: math.PR cond-mat.stat-mech math.ST physics.data-an stat.TH


title:
Extrinsic and intrinsic correlations in molecular information
  transmission

abstract:
  Cells measure concentrations of external ligands by capturing ligand
molecules with cell surface receptors. The numbers of molecules captured by
different receptors co-vary because they depend on the same extrinsic ligand
fluctuations. However, these numbers also counter-vary due to the intrinsic
stochasticity of chemical processes because a single molecule randomly captured
by a receptor cannot be captured by another. Such structure of receptor
correlations is generally believed to lead to an increase in information about
the external signal compared to the case of independent receptors. We analyze a
solvable model of two molecular receptors and show that, contrary to this
widespread expectation, the correlations have a small and negative effect on
the information about the ligand concentration. Further, we show that
measurements that average over multiple receptors are almost as informative as
those that track the states of every individual one.


title: Generation of spin-dependent coherent states in a quantum wire

abstract:
  We propose an all-electrically controlled nanodevice - a gated semiconductor
nanowire - capable of generating a coherent state of a single electron trapped
in a harmonic oscillator or superposition of such coherent states - the
Schr\"odinger cat state. In the proposed scheme, electron in the ground state
of the harmonic potential is driven by resonantly oscillating Rashba spin-orbit
coupling. This allows for the creation of the Schr\"odinger cat state with
superposition amplitudes depending on the initial electron spin state. Such a
method can be used for initialization of a single spin qubit defined in a
coherent state. The harmonic confinement potential along the InSb nanowire and
the modulation of the Rashba spin-orbit coupling is obtained by proper gating.
The results are supported by realistic three-dimensional time-dependent self
consistent Poisson-Schr\"odinger calculations.


title: A better lower bound on average degree of 4-list-critical graphs

abstract:
  This short note proves that every incomplete $k$-list-critical graph has
average degree at least $k-1 + \frac{k-3}{k^2-2k+2}$. This improves the best
known bound for $k = 4,5,6$. The same bound holds for online $k$-list-critical
graphs.


title: A Rank-Based Approach to Zipf's Law

abstract:
  An Atlas model is a rank-based system of continuous semimartingales for which
the steady-state values of the processes follow a power law, or Pareto
distribution. For a power law, the log-log plot of these steady-state values
versus rank is a straight line. Zipf's law is a power law for which the slope
of this line is -1. In this note, rank-based conditions are found under which
an Atlas model will follow Zipf's law. An advantage of this rank-based approach
is that it provides information about the dynamics of systems that result in
Zipf's law.


title:
Analysis and Design of Secure Massive MIMO Systems in the Presence of
  Hardware Impairments

abstract:
  To keep the hardware costs of future communications systems manageable, the
use of low-cost hardware components is desirable. This is particularly true for
the emerging massive multiple-input multiple-output (MIMO) systems which equip
base stations (BSs) with a large number of antenna elements. However, low-cost
transceiver designs will further accentuate the hardware impairments which are
present in any practical communication system. In this paper, we investigate
the impact of hardware impairments on the secrecy performance of downlink
massive MIMO systems in the presence of a passive multiple-antenna
eavesdropper. Thereby, for the BS and the legitimate users, the joint effects
of multiplicative phase noise, additive distortion noise, and amplified
receiver noise are taken into account, whereas the eavesdropper is assumed to
employ ideal hardware. We derive a lower bound for the ergodic secrecy rate of
a given user when matched filter (MF) data precoding and artificial noise (AN)
transmission are employed at the BS. Based on the derived analytical
expression, we investigate the impact of the various system parameters on the
secrecy rate and optimize both the pilot sets used for uplink training and the
AN precoding. Our analytical and simulation results reveal that 1) the additive
distortion noise at the BS may be beneficial for the secrecy performance,
especially if the power assigned for AN emission is not sufficient; 2) all
other hardware impairments have a negative impact on the secrecy performance;
3) {\textcolor{blue}{despite their susceptibility to pilot interference in the
presence of phase noise}}, so-called spatially orthogonal pilot sequences are
preferable unless the phase noise is very strong; 4) the proposed generalized
null-space (NS) AN precoding method can efficiently mitigate the negative
effects of phase noise.


title: Quandle Identities and Homology

abstract:
  Quandle homology was defined from rack homology as the quotient by a
subcomplex corresponding to the idempotency, for invariance under the type I
Reidemeister move. Similar subcomplexes have been considered for various
identities of racks and moves on diagrams. We observe common aspects of these
identities and subcomplexes; a quandle identity gives rise to a $2$-cycle, the
abelian extension with a $2$-cocycle that vanishes on the $2$-cycle inherits
the identity, and a subcomplex is constructed from the identity. Specific
identities are examined among small connected quandles.


title:
Qubit representations of the braid groups from generalized Yang-Baxter
  matrices

abstract:
  Generalized Yang-Baxter matrices sometimes give rise to braid group
representations. We identify the exact images of some qubit representations of
the braid groups from generalized Yang-Baxter matrices obtained from anyons in
the metaplectic modular categories.


title: Fishlike Rheotaxis

abstract:
  Fish rheotaxis, or alignment into flow currents, results from intertwined
sensory, neural and actuation mechanisms, all coupled with hydrodynamics to
produce a behavior that is critical for upstream migration and position holding
in oncoming flows. Among several sensory modalities, the lateral line sensory
system is thought to play a major role in the fish ability to sense minute
water motions in their vicinity and, thus, in their rheotactic behavior. Here,
we propose a theoretical model consisting of a fishlike body equipped with
lateral pressure sensors in oncoming uniform flows. We compute the optimal
sensor locations that maximize the sensory output. Our results confirm recent
experimental findings that correlate the layout of the lateral line sensors
with the distribution of hydrodynamic information at the fish surface. We then
examine the behavioral response of the fishlike model as a function of its
orientation and swimming speed relative to the background flow. Our working
hypothesis is that fish respond to sensory information by adjusting their
orientation according to the perceived difference in pressure. We find that, as
in fish rheotaxis, the fishlike body responds by aligning into the oncoming
flow. These findings may have significant implications on understanding the
interplay between the sensory output and fish behavior.


title: Random Chain Complexes

abstract:
  We study random, finite-dimensional, ungraded chain complexes over a finite
field and show that for a uniformly distributed differential a complex has the
smallest possible homology with the highest probability: either zero or
one-dimensional homology depending on the parity of the dimension of the
complex. We prove that as the order of the field goes to infinity the
probability distribution concentrates in the smallest possible dimension of the
homology. On the other hand, the limit probability distribution, as the
dimension of the complex goes to infinity, is a super-exponentially decreasing,
but strictly positive, function of the dimension of the homology.


title:
Beams of particles and papers. How digital preprint archives shape
  authorship and credit

abstract:
  In high energy physics, scholarly papers circulate primarily through online
preprint archives based on a centralized repository, arXiv, that physicists
simply refer to as "the archive". This is not just a tool for preservation and
memory, but also a space of flows where written objects are detected and their
authors made available for scrutiny. In this work I analyze the reading and
publishing practices of two subsets of high energy physicists: theorists and
experimentalists. In order to be recognized as legitimate and productive
members of their community, they need to abide by the temporalities and
authorial practices structured by the archive. Theorists live in a state of
accelerated time that shapes their reading and publishing practices around
precise cycles. Experimentalists turn to tactics that allow them to circumvent
the slowed-down time and invisibility they experience as members of large
collaborations. As digital platforms for the exchange of scholarly articles
emerge in other fields, high energy physics could help shed light on general
transformations of contemporary scholarly communication systems.


title: Improving on the Cut-Set Bound via Geometric Analysis of Typical Sets

abstract:
  We consider the discrete memoryless symmetric primitive relay channel, where,
a source $X$ wants to send information to a destination $Y$ with the help of a
relay $Z$ and the relay can communicate to the destination via an error-free
digital link of rate $R_0$, while $Y$ and $Z$ are conditionally independent and
identically distributed given $X$. We develop two new upper bounds on the
capacity of this channel that are tighter than existing bounds, including the
celebrated cut-set bound. Our approach significantly deviates from the standard
information-theoretic approach for proving upper bounds on the capacity of
multi-user channels. We build on the blowing-up lemma to analyze the
probabilistic geometric relations between the typical sets of the $n$-letter
random variables associated with a reliable code for communicating over this
channel. These relations translate to new entropy inequalities between the
$n$-letter random variables involved.
  As an application of our bounds, we study an open question posed by (Cover,
1987), namely, what is the minimum needed $Z$-$Y$ link rate $R_0^*$ in order
for the capacity of the relay channel to be equal to that of the broadcast cut.
We consider the special case when the $X$-$Y$ and $X$-$Z$ links are both binary
symmetric channels. Our tighter bounds on the capacity of the relay channel
immediately translate to tighter lower bounds for $R_0^*$. More interestingly,
we show that when $p\to 1/2$, $R_0^*\geq 0.1803$; even though the broadcast
channel becomes completely noisy as $p\to 1/2$ and its capacity, and therefore
the capacity of the relay channel, goes to zero, a strictly positive rate $R_0$
is required for the relay channel capacity to be equal to the broadcast bound.


title: Voids in cosmological simulations over cosmic time

abstract:
  We study evolution of voids in cosmological simulations using a new method
for tracing voids over cosmic time. The method is based on tracking watershed
basins (contiguous regions around density minima) of well developed voids at
low redshift, on a regular grid of density field. It enables us to construct a
robust and continuous mapping between voids at different redshifts, from
initial conditions to the present time. We discuss how the new approach
eliminates strong spurious effects of numerical origin when voids evolution is
traced by matching voids between successive snapshots (by analogy to halo
merger trees). We apply the new method to a cosmological simulation of a
standard LambdaCDM cosmological model and study evolution of basic properties
of typical voids (with effective radii between 6Mpc/h and 20Mpc/h at redshift
z=0) such as volumes, shapes, matter density distributions and relative
alignments. The final voids at low redshifts appear to retain a significant
part of the configuration acquired in initial conditions. Shapes of voids
evolve in a collective way which barely modifies the overall distribution of
the axial ratios. The evolution appears to have a weak impact on mutual
alignments of voids implying that the present state is in large part set up by
the primordial density field. We present evolution of dark matter density
profiles computed on iso-density surfaces which comply with the actual shapes
of voids. Unlike spherical density profiles, this approach enables us to
demonstrate development of theoretically predicted bucket-like shape of the
final density profiles indicating a wide flat core and a sharp transition to
high-density void walls.


title: Exact Solutions of a Fully Nonlinear Two-Fluid Model

abstract:
  A nonlinear coupled Choi-Camassa model describing one-dimensional
incompressible motion of two non-mixing fluid layers in a horizontal channel
has been derived in Ref.1. An equivalence transformation is presented, leading
to a special dimensionless form of the system, with the number of constant
physical parameters reduced from five to one. A first-order dimensionless
ordinary differential equation describing traveling wave solutions is analyzed.
Several multi-parameter families of exact closed-form solutions of the
Choi-Camassa model are obtained, describing periodic, solitary, and kink-type
bidirectional traveling waves.


title: Hydrodynamic modes of conducting liquid in random magnetic field

abstract:
  Hydrodynamics of plasma in the random magnetic field is considered, which is
characterized by the second moment of magnetic induction. Equations of ideal
magnetic hydrodynamics in such field are received for an adiabatic process. It
is shown that in Euler Equation a new variable is second moment of magnetic
induction enters, for which is received time Equation on the basis of Maxwell
Equations in the magnetohydrodynamic approximation. The one dimension plane
waves in this system are studied and the values of their phase velocities are
received.


title: Minimal energy problems for strongly singular Riesz kernels

abstract:
  We study minimal energy problems for strongly singular Riesz kernels on a
manifold. Based on the spatial energy of harmonic double layer potentials, we
are motivated to formulate the natural regularization of such problems by
switching to Hadamard's partie finie integral operator which defines a strongly
elliptic pseudodifferential operator on the manifold. The measures with finite
energy are shown to be elements from the corresponding Sobolev space, and the
associated minimal energy problem admits a unique solution. We relate our
continuous approach also to the discrete one, which has been worked out earlier
by D.P. Hardin and E.B. Saff.


title: The Bernstein inequality for slice regular polynomials

abstract:
  Due to the invalidation of the Gauss-Lucas type result for quaternionic
polynomials, we first give in this paper an alternative proof of the Bernstein
inequality in $L^{p} (1\leq p \leq+\infty)$ for slice regular polynomials by
the Fej\'er kernel and the Minkowski inequality. Secondly, we extend a result
of Ankeny-Rivlin to the quaternionic setting via the Hopf lemma. By the way,
some Turan inequalities are established for slice regular polynomials.


title: Locality of correlation in density functional theory

abstract:
  The Hohenberg-Kohn density functional was long ago shown to reduce to the
Thomas-Fermi approximation in the non-relativistic semiclassical (or large-$Z$)
limit for all matter, i.e, the kinetic energy becomes local. Exchange also
becomes local in this limit. Numerical data on the correlation energy of atoms
supports the conjecture that this is also true for correlation, but much less
relevant to atoms. We illustrate how expansions around large particle number
are equivalent to local density approximations and their strong relevance to
density functional approximations. Analyzing highly accurate atomic correlation
energies, we show that the correlation energy tends to $-A_c Z ln Z + B_c Z$ as
$Z$ tends to infinity, where $Z$ is the atomic number, $A_c$ is known, and we
estimate $B_c$ to be about 37 millihartrees. The local density approximation
yields $A_c$ exactly, but a very incorrect value for $B_c$, showing that the
local approximation is less relevant for correlation alone. This limit is a
benchmark for the non-empirical construction of density functional
approximations. We conjecture that, beyond atoms, the leading correction to the
local density approximation in the large-$Z$ limit generally takes this form,
but with $B_c$ a functional of the TF density for the system. The implications
for construction of approximate density functionals are discussed.