title:
Temporal dynamics in immunological synapse: Role of thermal fluctuations
  in signaling

abstract:
  The article analyzes the contribution of stochastic thermal fluctuations in
the attachment times of the immature T-cell receptor TCR:
peptide-major-histocompatibility-complex pMHC immunological synapse bond. The
key question addressed here is the following: how does a synapse bond remain
stabilized in the presence of high frequency thermal noise that potentially
equates to a strong detaching force? Focusing on the average time persistence
of an immature synapse, we show that the high frequency nodes accompanying
large fluctuations are counterbalanced by low frequency nodes that evolve over
longer time periods. Our analysis shows that such a behavior could be easily
explained from the fact that the survival probability distribution is governed
by two distinct phases, for the two different time regimes. The relatively
shorter time scales correspond to the cohesion:adhesion induced immature bond
formation whereas the larger time reciprocates the association:dissociation
regime leading to TCR:pMHC signaling. From an estimation of the bond survival
probability, we show that at shorter time scales, this probability
$P_{\Delta}(\tau)$ scales with time $\tau$ as an universal function of a
rescaled noise amplitude $\frac{D}{\Delta^2}$, such that $P_{\Delta}(\tau)\sim
\tau^{-(\frac{\Delta}{\sqrt{D}}+\frac{1}{2})}$, $\Delta$ being the distance
from the mean inter-membrane (T cell:Antigen Presenting Cell) separation
distance. The crossover from this shorter to a longer time regime leads to an
universality in the dynamics, at which point the survival probability shows a
different power-law scaling compared to the one at shorter time scales. In
biological terms, such a crossover indicates that the TCR:pMHC bond has a
survival probability with a slower decay rate than the longer LFA-1:ICAM-1 bond
justifying its stability.

categories: q-bio.SC cond-mat.soft cond-mat.stat-mech q-bio.BM


title:
Total kinetic energy release in the fast neutron-induced fission of
  $^{235}$U

abstract:
  We have measured the total kinetic energy (TKE) release for the
$^{235}$U(n,f) reaction for $E_{n}$=2-100 MeV using the 2E method with an array
of Si PIN diode detectors. The neutron energies were determined by time of
flight measurements using the white spectrum neutron beam at the LANSCE
facility. To benchmark the TKE measurement, the TKE release for
$^{235}$U(n$_{th}$,f) was also measured using a thermal neutron beam from the
Oregon State University TRIGA reactor, giving pre-neutron emission
$E^*_{TKE}=170.7\pm0.4$ MeV in good agreement with known values. Our
measurements are thus absolute measurements. The TKE in $^{235}$U(n,f)
decreases non-linearly from 169 MeV to 161 MeV for $E_{n}$=2-100 MeV. The
multi-modal fission analysis of mass distributions and TKE indicates the origin
of the TKE decrease with increasing neutron energy is a consequence of the fade
out of asymmetric fission, which is associated with a higher TKE compared to
symmetric fission. The average TKE associated with the superlong, standard I
and standard II modes for a given mass is independent of neutron energy. The
widths of the TKE distributions are constant from $E_{n}$=20-100 MeV and hence
show no dependence with excitation energy.


title:
Modeling Mechanical Properties of Aluminum Composite Produced Using Stir
  Casting Method

abstract:
  ANN (Artificial Neural Networks) modeling methodology was adopted for
predicting mechanical properties of aluminum cast composite materials. For this
purpose aluminum alloy were developed using conventional foundry method. The
composite materials have complex nature which posses the nonlinear relationship
among heat treatment, processing parameters, and composition and affects their
mechanical properties. These nonlinear relation ships with properties can more
efficiently be modeled by ANNs. Neural networks modeling needs sufficient data
base consisting of mechanical properties, chemical composition and processing
parameters. Such data base is not available for modeling. Therefore, a large
range of experimental work was carried out for the development of aluminum
composite materials. Alloys containing Cu, Mg and Zn as matrix were reinforced
with 1- 15% Al2O3 particles using stir casting method. Alloys composites were
cast in a metal mold. More than eighty standard samples were prepared for
tensile tests. Sixty samples were given solution treatments at 580oC for half
an hour and tempered at 120oC for 24 hours. The samples were characterized to
investigate mechanical properties using Scanning Electron Microscope, X-Ray
Spectrometer, Optical Metallurgical Microscope, Vickers Hardness, Universal
Testing Machine and Abrasive Wear Testing Machine. A MLP (Multilayer
Perceptron) feedforward was developed and used for modeling purpose. Training,
testing and validation of the model were carried out using back propagation
learning algorithm. The modeling results show that an architecture of 14 inputs
with 9 hidden neurons and 4 outputs which includes the tensile strength,
elongation, hardness and abrasive wear resistance gives reasonably accurate
results with an error within the range of 2-7 % in training, testing and
validation.


title: Tightening the uncertainty principle for stochastic currents

abstract:
  We connect two recent advances in the stochastic analysis of nonequilibrium
systems: the (loose) uncertainty principle for the currents, which states that
statistical errors are bounded by thermodynamic dissipation; and the analysis
of thermodynamic consistency of the currents in the light of symmetries.
Employing the large deviation techniques presented in [Gingrich et al., Phys.
Rev. Lett. 2016] and [Pietzonka et al., Phys. Rev. E 2016], we provide a short
proof of the loose uncertainty principle, and prove a tighter uncertainty
relation for a class of thermodynamically consistent currents $J$. Our bound
involves a measure of partial entropy production, that we interpret as the
least amount of entropy that a system sustaining current $J$ can possibly
produce, at a given steady state. We provide a complete mathematical discussion
of quadratic bounds which allows to determine which are optimal, and finally we
argue that the relationship for the Fano factor of the entropy production rate
$\mathrm{var}\, \sigma / \mathrm{mean}\, \sigma \geq 2$ is the most significant
realization of the loose bound. We base our analysis both on the formalism of
diffusions, and of Markov jump processes in the light of Schnakenberg's cycle
analysis.


title: Index and topology of minimal hypersurfaces in R^n

abstract:
  In this paper, we consider immersed two-sided minimal hypersurfaces in
$\mathbb{R}^n$ with finite total curvature. We prove that the sum of the Morse
index and the nullity of the Jacobi operator is bounded from below by a linear
function of the number of ends and the first Betti number of the hypersurface.
When $n=4$, we are able to drop the nullity term by a careful study for the
rigidity case. Our result is the first effective generalization of Li-Wang.
Using our index estimates and ideas from the recent work of
Chodosh-Ketover-Maximo, we prove compactness and finiteness results of minimal
hypersurfaces in $\mathbb{R}^4$ with finite index.


title:
Hadronization conditions in relativistic nuclear collisions and the QCD
  pseudo-critical line

abstract:
  We compare the reconstructed hadronization conditions in relativistic nuclear
collisions in the nucleon-nucleon centre-of-mass energy range 4.7-2760 GeV in
terms of temperature and baryon-chemical potential with lattice QCD
calculations, by using hadronic multiplicities. We obtain hadronization
temperatures and baryon chemical potentials with a fit to measured
multiplicities by correcting for the effect of post-hadronization rescattering.
The post-hadronization modification factors are calculated by means of a
coupled hydrodynamical-transport model simulation under the same conditions of
approximate isothermal and isochemical decoupling as assumed in the statistical
hadronization model fits to the data. The fit quality is considerably better
than without rescattering corrections, as already found in previous work. The
curvature of the obtained "true" hadronization pseudo-critical line kappa is
found to be 0.0048 +- 0.0026, in agreement with lattice QCD estimates; the
pseudo-critical temperature at vanishing mu_B is found to be 164.3+-1.8 MeV.


title:
Finite stopping times for freely oscillating drop of a yield stress
  fluid

abstract:
  The paper addresses the question if there exists a finite stopping time for
an unforced motion of a yield stress fluid with free surface. A variation
inequality formulation is deduced for the problem of yield stress fluid
dynamics with a free surface. Free surface is assumed to evolve with a normal
velocity the flow. We also consider capillary forces acting along the free
surface. Based on the variational inequality formulation an energy equality is
obtained, where kinetic and free energy rate of change is in a balance with the
internal energy viscoplastic dissipation and the work of external forces.
Further, the paper considers free small-amplitude oscillations of a droplet of
Herschel-Bulkley fluid under the action of surface tension forces. Under
certain assumptions it is shown that the finite stopping time $T_f$ of
oscillations exists once the yield stress parameter is positive and the flow
index $\alpha$ satisfies ($\alpha\ge1$). Results of several numerical
experiments illustrate the analysis, reveal the dependence of $T_f$ on problem
parameters and suggest an instantaneous transition of the whole drop from
yielding state to the rigid one.


title:
Generalized Multi-view Embedding for Visual Recognition and Cross-modal
  Retrieval

abstract:
  In this paper, the problem of multi-view embedding from different visual cues
and modalities is considered. We propose a unified solution for subspace
learning methods using the Rayleigh quotient, which is extensible for multiple
views, supervised learning, and non-linear embeddings. Numerous methods
including Canonical Correlation Analysis, Partial Least Sqaure regression and
Linear Discriminant Analysis are studied using specific intrinsic and penalty
graphs within the same framework. Non-linear extensions based on kernels and
(deep) neural networks are derived, achieving better performance than the
linear ones. Moreover, a novel Multi-view Modular Discriminant Analysis (MvMDA)
is proposed by taking the view difference into consideration. We demonstrate
the effectiveness of the proposed multi-view embedding methods on visual object
recognition and cross-modal image retrieval, and obtain superior results in
both applications compared to related methods.


title: Mutations as Levy flights

abstract:
  Data from a long time evolution experiment with Escherichia Coli and from a
large study on copy number variations in subjects with european ancestry are
analyzed in order to argue that mutations can be described as Levy flights in
the mutation space. These Levy flights have at least two components: random
single-base substitutions and large DNA rearrangements. From the data, we get
estimations for the time rates of both events and the size distribution
function of large rearrangements.


title:
Preparation and characterization of ultra-hydrophobic calcium carbonate
  nanoparticles

abstract:
  Anionic surfactants based on fatty acids are usually used to modify the
particle surface properties of CaCO$_3$ with the aim to enhance its dispersion
and compatibility with polymer matrices. In this study sodium oleate was used
for the preparation of ultra-hydrophobic CaCO$_3$ nanoparticles using a wet
carbonation route. The effect of sodium oleate on the characteristics, particle
size, morphology, surface potential, thermal decomposition and hydrophobicity
of CaCO$_3$, was investigated using X-ray diffraction (XRD), Fourier transform
infrared spectroscopy (FTIR), transmission electron microscopy (TEM), Zeta
potential, thermogravimetric analysis (TGA) and water contact angle measurement
(WCA). The results showed that the addition of 2 wt% sodium oleate helps in
reducing the particle size from 2 {\mu}m length scalenohedral particles to 45
nm rhombohedral particles and modifying of the hydrophobic property of
CaCO$_3$.


title: Mal'tsev objects, $R_1$-spaces and ultrametric spaces

abstract:
  In this paper we introduce a notion of Mal'tsev object, and the dual notion
of co-Mal'tsev object, in a general category. In particular, a category
$\mathbb{C}$ is a Mal'tsev category if and only if every object in $\mathbb{C}$
is a Mal'tsev object. We show that for a well-powered regular category
$\mathbb{C}$ which admits coproducts, the full subcategory of Mal'tsev objects
is coreflective in $\mathbb{C}$. We show that the co-Mal'tsev objects in the
category of topological spaces and continuous maps are precisely the
$R_1$-spaces, and that the co-Mal'tsev objects in the category of metric spaces
and short maps are precisely the ultrametric spaces.


title:
Modified Signed Log-Likelihood Ratio Test for Comparing the Correlation
  Coefficients of Two Independent Bivariate Normal Distributions

abstract:
  In this paper, we use the method of modified signed log-likelihood ratio test
for the problem of testing the equality of correlation coefficients in two
independent bivariate normal distributions. We compare this method with two
other %competing approaches, Fisher's Z-transform and generalized test
variable, using a Monte Carlo simulation. It indicates that the proposed method
is better than the other approaches, in terms of the actual sizes and powers
especially when the sample sizes are unequal. We illustrate performance of the
proposed approach, using a real data set.


title:
Quantization for uniform distributions on stretched Sierpi\'nski
  triangles

abstract:
  In this paper, we have considered a uniform probability distribution
supported by a stretched Sierpi\'nski triangle. For this probability measure,
the optimal sets of $n$-means and the $n$th quantization errors are determined
for all $n\geq 2$. In addition, it is shown that the quantization coefficient
for such a measure does not exist though the quantization dimension exists.


title: Rigidity and stability of Caffarelli's log-concave perturbation theorem

abstract:
  In this note we establish some rigidity and stability results for
Caffarelli's log-concave perturbation theorem. As an application we show that
if a 1-log-concave measure has almost the same Poincar\'e constant as the
Gaussian measure, then it almost splits off a Gaussian factor.


title:
Policy learning for time-bounded reachability in Continuous-Time Markov
  Decision Processes via doubly-stochastic gradient ascent

abstract:
  Continuous-time Markov decision processes are an important class of models in
a wide range of applications, ranging from cyber-physical systems to synthetic
biology. A central problem is how to devise a policy to control the system in
order to maximise the probability of satisfying a set of temporal logic
specifications. Here we present a novel approach based on statistical model
checking and an unbiased estimation of a functional gradient in the space of
possible policies. The statistical approach has several advantages over
conventional approaches based on uniformisation, as it can also be applied when
the model is replaced by a black box, and does not suffer from state-space
explosion. The use of a stochastic gradient to guide our search considerably
improves the efficiency of learning policies. We demonstrate the method on a
proof-of-principle non-linear population model, showing strong performance in a
non-trivial task.


title: Index estimates for free boundary minimal hypersurfaces

abstract:
  We show that the Morse index of a properly embedded free boundary minimal
hypersurface in a strictly mean convex domain of the Euclidean space grows
linearly with the dimension of its first relative homology group (which is at
least as big as the number of its boundary components, minus one). In ambient
dimension three, this implies a lower bound for the index of a free boundary
minimal surface which is linear both with respect to the genus and the number
of boundary components. Thereby, the compactness theorem by Fraser and Li
implies a strong compactness theorem for the space of free boundary minimal
surfaces with uniformly bounded Morse index inside a convex domain. Our
estimates also imply that the examples constructed, in the unit ball, by
Fraser-Schoen and Folha-Pacard-Zolotareva have arbitrarily large index.
Extensions of our results to more general settings (including various classes
of positively curved Riemannian manifolds and other convexity assumptions) are
discussed.


title: Embeddings of decomposition spaces

abstract:
  Many smoothness spaces in harmonic analysis are decomposition spaces. In this
paper we ask: Given two decomposition spaces, is there an embedding between the
two?
  A decomposition space $\mathcal{D}(\mathcal{Q}, L^p, Y)$ can be described
using : a covering $\mathcal{Q}=(Q_{i})_{i\in I}$ of the frequency domain, an
exponent $p$ and a sequence space $Y\subset\mathbb{C}^{I}$. Given these, the
decomp. space norm of a distribution $g$ is $\| g\| _{\mathcal{D}(\mathcal{Q},
L^p, Y)}=\left\| \left(\left\|
\mathcal{F}^{-1}\left(\varphi_{i}\widehat{g}\right)\right\|
_{L^{p}}\right)_{i\in I}\right\| _{Y}$, where $(\varphi_{i})_{i\in I}$ is a
suitable partition of unity for $\mathcal{Q}$.
  We establish readily verifiable criteria which ensure an embedding
$\mathcal{D}(\mathcal{Q}, L^{p_1}, Y)\hookrightarrow\mathcal{D}(\mathcal{P},
L^{p_2}, Z)$, mostly concentrating on the case, $Y=\ell_{w}^{q_{1}}(I)$ and
$Z=\ell_{v}^{q_{2}}(J)$.
  The relevant sufficient conditions are $p_{1}\leq p_{2}$, and finiteness of a
norm of the form \[ \left\| \left(\left\| (\alpha_{i}\,\beta_j \cdot
v_{j}/w_{i})_{i\in I_{j}}\right\| _{\ell^{t}}\right)_{j\in J}\right\|
_{\ell^{s}}<\infty, \] where the \[ I_{j}=\{ i\in I : Q_{i}\cap
P_{j}\neq\emptyset\} \qquad\text{ for }j\in J \] are defined in terms of the
two coverings $\mathcal{Q}=(Q_{i})_{i\in I}$ and $\mathcal{P}=(P_{j})_{j\in
J}$.
  We also show that these criteria are sharp: For almost arbitrary coverings
and certain ranges of $p_{1},p_{2}$, our criteria yield a complete
characterization. The same holds for arbitrary values of $p_{1},p_{2}$ under
more strict assumptions on the coverings.
  We illustrate the resulting theory by applications to $\alpha$-modulation and
Besov spaces. All known embedding results for these spaces are special cases of
our approach; often, we improve considerably upon the state of the art.


title:
Approximate Green's Function for the Conductivity Equation With Conormal
  Coefficient

abstract:
  We construct an approximate Green's function for $L_{\gamma}=\nabla \cdot
\gamma(x) \nabla u(x)$, which belongs to a class of Fourier Integral Operators
(FIOs) associated to two canonical relations. This leads to analysis of the
composition of two FIOs, associated to a canonical relation with a zero section
problem. The resulting composition is a sum of two FIOs, each associated to two
intersecting canonical relations.


title:
CSO and CARMA Observations of L1157. II. Chemical Complexity in the
  Shocked Outflow

abstract:
  L1157, a molecular dark cloud with an embedded Class 0 protostar possessing a
bipolar outflow, is an excellent source for studying shock chemistry, including
grain-surface chemistry prior to shocks, and post-shock, gas-phase processing.
The L1157-B1 and B2 positions experienced shocks at an estimated ~2000 and 4000
years ago, respectively. Prior to these shock events, temperatures were too low
for most complex organic molecules to undergo thermal desorption. Thus, the
shocks should have liberated these molecules from the ice grain-surfaces en
masse, evidenced by prior observations of SiO and multiple grain mantle species
commonly associated with shocks. Grain species, such as OCS, CH3OH, and HNCO,
all peak at different positions relative to species that are preferably formed
in higher velocity shocks or repeatedly-shocked material, such as SiO and HCN.
Here, we present high spatial resolution (~3") maps of CH3OH, HNCO, HCN, and
HCO+ in the southern portion of the outflow containing B1 and B2, as observed
with CARMA. The HNCO maps are the first interferometric observations of this
species in L1157. The maps show distinct differences in the chemistry within
the various shocked regions in L1157B. This is further supported through
constraints of the molecular abundances using the non-LTE code RADEX (Van der
Tak et al. 2007). We find the east/west chemical differentiation in C2 may be
explained by the contrast of the shock's interaction with either cold, pristine
material or warm, previously-shocked gas, as seen in enhanced HCN abundances.
In addition, the enhancement of the HNCO abundance toward the the older shock,
B2, suggests the importance of high-temperature O-chemistry in shocked regions.


title:
Belavin-Drinfeld quantum groups and Lie bialgebras: Galois cohomology
  considerations

abstract:
  We relate the Belavin--Drinfeld cohomologies (twisted and untwisted) that
have been introduced in the literature to study certain families of quantum
groups and Lie bialgebras over a non algebraically closed field $\mathbb K$ of
characteristic 0 to the standard non-abelian Galois cohomology $H^1(\mathbb K,
\mathbf H)$ for a suitable algebraic $\mathbb K$-group $\mathbf H.$ The
approach presented allows us to establish in full generality certain
conjectures that were known to hold for the classical types of the split simple
Lie algebras.


title: Codimension two holomorphic foliations

abstract:
  This paper is devoted to the study of codimension two holomorphic foliations
and distributions. We prove the stability of complete intersection of
codimension two distributions and foliations in the local case. Converserly we
show the existence of codimension two foliations which are not contained in any
codimension one foliation. We study problems related to the singular locus and
we classify homogeneous foliations of small degree.


title:
Prediction of allosteric sites and mediating interactions through
  bond-to-bond propensities

abstract:
  Allosteric regulation is central to many biochemical processes. Allosteric
sites provide a target to fine-tune protein activity, yet we lack computational
methods to predict them. Here, we present an efficient graph-theoretical
approach for identifying allosteric sites and the mediating interactions that
connect them to the active site. Using an atomistic graph with edges weighted
by covalent and non-covalent bond energies, we obtain a bond-to-bond propensity
that quantifies the effect of instantaneous bond fluctuations propagating
through the protein. We use this propensity to detect the sites and
communication pathways most strongly linked to the active site, assessing their
significance through quantile regression and comparison against a reference set
of 100 generic proteins. We exemplify our method in detail with three
well-studied allosteric proteins: caspase-1, CheY, and h-Ras, correctly
predicting the location of the allosteric site and identifying key allosteric
interactions. Consistent prediction of allosteric sites is then attained in a
further set of 17 proteins known to exhibit allostery. Because our propensity
measure runs in almost linear time, it offers a scalable approach to
high-throughput searches for candidate allosteric sites.

categories: q-bio.BM physics.bio-ph physics.data-an q-bio.QM


title:
Multi-layer Mechanism for Multicast Routing in Multihop Cognitive Radio
  Networks

abstract:
  Multicast routing is considered as one of the most important process in
Mobile Ad hoc Networks (MANETs) to enable video sharing and data dissemination.
Multicast routing can be used without any difficulties if a medium can be
accessed by any transmitter at any given time. Unfortunately, challenges such
as the unexpected behavior of primary users (PUs) and their access priority as
well as network heterogeneity may appear in cognitive radio networks (CRNs). In
this thesis, we propose a multi-layer multicast routing protocol for multi-hop
mobile Ad Hoc CRN based on the concept of the minimum spanning tree (MST) and
the shortest path tree (SPT). The proposed algorithm employs the probability of
success (POS) metric in performing the channel assignment process. Simulations
experiments were conducted, to investigate the effectiveness of the proposed
scheme, compare the performance of the proposed scheme with
the-state-of-the-art schemes, and study the performance of the proposed scheme
under various network conditions in terms of throughput and packet delivery
rate (PDR). Simulations results show that the SPT outperforms MST in term of
throughput all the time.


title:
Motion of Patterns Modeled by the Gray-Scott Autocatalysis System in One
  Dimension

abstract:
  Occupation of an interval by self-replicating initial pulses is studied
numerically. Two different approximates in different categories are proposed
for the numerical solutions of some initial-boundary value problems. The sinc
differential quadrature combined with third-fourth order implicit Rosenbrock
and exponential B-spline collocation methods are setup to obtain the numerical
solutions of the mentioned problems. The numerical simulations containing
occupation of single initial pulse, non or slow occupation model and covering
the domain with two initial pulses are demonstrated by using both proposed
methods.


title: Mechanics and polarity in cell motility

abstract:
  The motility of a fish keratocyte on a flat substrate exhibits two distinct
regimes: the non-migrating and the migrating one. In both configurations the
shape is fixed in time and, when the cell is moving, the velocity is constant
in magnitude and direction. Transition from a stable configuration to the other
one can be produced by a mechanical or chemotactic perturbation. In order to
point out the mechanical nature of such a bistable behaviour, we focus on the
actin dynamics inside the cell using a minimal mathematical model. While the
protein diffusion, recruitment and segregation govern the polarization process,
we show that the free actin mass balance, driven by diffusion, and the
polymerized actin retrograde flow, regulated by the active stress, are
sufficient ingredients to account for the motile bistability. The length and
velocity of the cell are predicted on the basis of the parameters of the
substrate and of the cell itself. The key physical ingredient of the theory is
the exchange among actin phases at the edges of the cell, that plays a central
role both in kinematics and in dynamics.


title:
Magnetic excitations and electronic interactions in Sr$_2$CuTeO$_6$: a
  spin-1/2 square lattice Heisenberg antiferromagnet

abstract:
  Sr$_2$CuTeO$_6$ presents an opportunity for exploring low-dimensional
magnetism on a square lattice of $S=1/2$ Cu$^{2+}$ ions. We employ ab initio
multi-reference configuration interaction calculations to unravel the Cu$^{2+}$
electronic structure and to evaluate exchange interactions in Sr$_2$CuTeO$_6$.
The latter results are validated by inelastic neutron scattering using linear
spin-wave theory and series-expansion corrections for quantum effects to
extract true coupling parameters. Using this methodology, which is quite
general, we demonstrate that Sr$_2$CuTeO$_6$ is an almost realization of a
nearest-neighbor Heisenberg antiferromagnet but with relatively weak coupling
of 7.18(5) meV.


title:
Analysis of Key Generation Rate from Wireless Channel in In-Band
  Full-Duplex Communications

abstract:
  In this paper, the impact of in-band full-duplex (IBFD) wireless
communications on secret key generation via physical layer channel state
information is investigated. A key generation strategy for IBFD wireless
devices to increase the rate of generated secret keys over multipath fading
channels is proposed. Conventionally, due to the half-duplex (HD) constraint on
wireless transmissions, sensing simultaneous reciprocal channel measurements is
not possible, which leads to a degraded key generation rate. However, with the
advent of IBFD wireless devices, the legitimate nodes can sense the shared
wireless link simultaneously at the possible cost of a self-interference (SI)
channel estimation and some residual self-interference (RSI). As we
demonstrate, with HD correlated observations the key rate is upper bounded by a
constant, while with IBFD the key rate is only limited by the SI cancellation
performance and is in general greater than that of its HD counterpart. Our
analysis shows that with reasonable levels of SI cancellation, in the high SNR
regime the key rate of IBFD is much higher, while in low SNRs, the HD system
performs better. Finally, the key rate loss due to the overhead imposed by the
SI channel estimation phase is discussed.


title:
RCFD: A Frequency Based Channel Access Scheme for Full Duplex Wireless
  Networks

abstract:
  Recently, several working implementations of in--band full--duplex wireless
systems have been presented, where the same node can transmit and receive
simultaneously in the same frequency band. The introduction of such a
possibility at the physical layer could lead to improved performance but also
poses several challenges at the MAC layer. In this paper, an innovative
mechanism of channel contention in full--duplex OFDM wireless networks is
proposed. This strategy is able to ensure efficient transmission scheduling
with the result of avoiding collisions and effectively exploiting full--duplex
opportunities. As a consequence, considerable performance improvements are
observed with respect to standard and state--of--the--art MAC protocols for
wireless networks, as highlighted by extensive simulations performed in ad hoc
wireless networks with varying number of nodes.


title: Detecting dark matter waves with precision measurement tools

abstract:
  Virialized Ultra-Light Fields (VULFs) are viable cold dark matter candidates
and include scalar and pseudo-scalar bosonic fields, such as axions and
dilatons. Direct searches for VULFs rely on low-energy precision measurement
tools. While the previous proposals have focused on detecting coherent
oscillations of the VULF signals at the VULF Compton frequencies at individual
devices, here I consider a network of such devices. VULFs are essentially dark
matter {\em waves} and as such they carry both temporal and spatial phase
information. Thereby, the discovery reach can be improved by using networks of
precision measurement tools. To formalize this idea, I derive a spatio-temporal
two-point correlation function for the ultralight dark matter fields in the
framework of the standard halo model. Due to VULFs being Gaussian random
fields, the derived two-point correlation function fully determines $N$-point
correlation functions. For a network of $N_{d}$ devices within the coherence
length of the field, the sensitivity compared to a single device can be
improved by a factor of $\sqrt{N_{d}}$. Further, I derive a VULF dark matter
signal profile for an individual device. The resulting line shape is strongly
asymmetric due to the parabolic dispersion relation for massive
non-relativistic bosons. I discuss the aliasing effect that extends the
discovery reach to VULF frequencies higher than the experimental sampling rate.
I present sensitivity estimates and develop a stochastic field SNR statistic.
Finally, I consider an application of the developed formalism to atomic clocks
and their networks.

categories: physics.atom-ph astro-ph.CO astro-ph.IM hep-ph physics.ins-det


title:
Recent Advances in the Theory and Simulation of Model Colloidal
  Microphase Formers

abstract:
  This mini-review synthesizes our understanding of the equilibrium behavior of
particle models with short-range attractive and long-range repulsive (SALR)
interactions. These models, which can form stable periodic microphases, aim to
reproduce the essence of colloidal suspensions with competing interactions.
Ordered structures, however, have yet to be obtained in experiments. In order
to better understand the hurdles to periodic microphase assembly, marked
theoretical and simulation advances have been made over the last few years.
Here, we present recent progress in the study of microphases in models with
SALR interactions using liquid-state theory and density-functional theory as
well as numerical simulations. Combining these various approaches provides a
description of periodic microphases, and give insights into the rich
phenomenology of the surrounding disordered regime. Three additional ongoing
research directions in the thermodynamics of models with SALR interactions are
also presented.


title: Modified perturbation theory for the Yukawa model

abstract:
  A new formulation of perturbation theory for a description of the Dirac and
scalar fields (the Yukawa model) is suggested. As the main approximation the
self-consistent field model is chosen, which allows in a certain degree to
account for the effects caused by the interaction of fields. Such choice of the
main approximation leads to a normally ordered form of the interaction
Hamiltonian. Generation of the fermion mass due to the interaction with
exchange of the scalar boson is investigated. It is demonstrated that, for zero
bare mass, the fermion can acquire mass only if the coupling constant exceeds
the critical value determined by the boson mass. In this connection, the
problem of the neutrino mass is discussed.


title: Endogenous Formation of Limit Order Books: Dynamics Between Trades

abstract:
  In this work, we present a continuous-time large-population game for modeling
market microstructure betweentwo consecutive trades. The proposed modeling
framework is inspired by our previous work [23]. In this framework, the Limit
Order Book (LOB) arises as an outcome of an equilibrium between multiple agents
who have different beliefs about the future demand for the asset. The agents'
beliefs may change according to the information they observe, triggering
changes in their behavior. We present an example illustrating how the proposed
models can be used to quantify the consequences of changes in relevant
information signals. If these signals, themselves, depend on the LOB, then, our
approach allows one to model the "indirect" market impact (as opposed to the
"direct" impact that a market order makes on the LOB, by eliminating certain
limit orders). On the mathematical side, we formulate the proposed modeling
framework as a continuum-player control-stopping game. We manage to split the
equilibrium problem into two parts. The first one is described by a
two-dimensional system of Reflected Backward Stochastic Differential Equations
(RBSDEs), whose solution components reflect against each other. The second one
leads to an infinite-dimensional fixed-point problem for a discontinuous
mapping. Both problems are non-standard, and we prove the existence of their
solutions in the paper.


title: CYCLADES: Conflict-free Asynchronous Machine Learning

abstract:
  We present CYCLADES, a general framework for parallelizing stochastic
optimization algorithms in a shared memory setting. CYCLADES is asynchronous
during shared model updates, and requires no memory locking mechanisms, similar
to HOGWILD!-type algorithms. Unlike HOGWILD!, CYCLADES introduces no conflicts
during the parallel execution, and offers a black-box analysis for provable
speedups across a large family of algorithms. Due to its inherent conflict-free
nature and cache locality, our multi-core implementation of CYCLADES
consistently outperforms HOGWILD!-type algorithms on sufficiently sparse
datasets, leading to up to 40% speedup gains compared to the HOGWILD!
implementation of SGD, and up to 5x gains over asynchronous implementations of
variance reduction algorithms.


title: Formality and Kontsevich--Duflo type theorems for Lie pairs

abstract:
  $\newcommand{\poly}{_{\operatorname{poly}}^{\bullet}}\newcommand{\td}{(\operatorname{td}_{L/A}^{\nabla})^{\frac{1}{2}}}\newcommand{\cx}[1]{\operatorname{tot}\big(\Gamma(\Lambda^\bullet
A^\vee)\otimes_R\mathcal{#1}\poly\big)}\newcommand{\cy}[1]{\mathbb{H}^\bullet_{\operatorname{CE}}(A,\mathcal{#1}\poly)}$Kontsevich's
formality theorem states that there exists an $L_\infty$ quasi-isomorphism from
the dgla $T\poly(M)$ of polyvector fields on a smooth manifold $M$ to the dgla
$D\poly(M)$ of polydifferential operators on $M$, which extends the classical
Hochschild--Kostant--Rosenberg map. In this paper, we extend Kontsevich's
formality theorem to Lie pairs, a framework which includes a range of diverse
geometric contexts such as complex manifolds, foliations, and
$\mathfrak{g}$-manifolds. The spaces $\cx{T}$ and $\cx{D}$ associated with a
Lie pair $(L,A)$ each carry an $L_\infty$ algebra structure canonical up to
$L_\infty$ isomorphism. These two spaces serve as replacements for the spaces
of polyvector fields and polydifferential operators, respectively. Their
corresponding cohomology groups $\cy{T}$ and $\cy{D}$ admit canonical
Gerstenhaber algebra structures. We establish the following formality theorem
for Lie pairs: there exists an $L_\infty$ quasi isomorphism from $\cx{T}$ to
$\cx{D}$ whose first Taylor coefficient is equal to
$\operatorname{hkr}\circ\td$. Here $\td$ acts on $\cx{T}$ by contraction.
Furthermore, we prove a Kontsevich--Duflo type theorem for Lie pairs: the
Hochschild--Kostant--Rosenberg map twisted by the square root of the Todd class
of the Lie pair $(L,A)$ is an isomorphism of Gerstenhaber algebras from
$\cy{T}$ to $\cy{D}$. As applications, we establish formality theorems and
Kontsevich--Duflo type theorems for complex manifolds, foliations, and
$\mathfrak{g}$-manifolds. In the case of complex manifolds, we recover the
Kontsevich--Duflo theorem of complex geometry.


title: Evidence of strong dynamic core excitation in $^{19}$C resonant break-up

abstract:
  The resonant break-up of $^{19}$C on protons measured at RIKEN [Phys. Lett. B
660, 320 (2008)] is analyzed in terms of a valence-core model for $^{19}$C
including possible core excitations. The analysis of the angular distribution
of a prominent peak appearing in the relative-energy spectrum could be well
described with this model and is consistent with the previous assignment of
$5/2^{+}$ for this state. Inclusion of core-excitation effects are found to be
essential to give the correct magnitude of the cross section for this state. By
contrast, the calculation assuming an inert $^{18}$C core is found to largely
underestimate the data.


title:
Understanding polyethylene surface functionalization by an atmospheric
  He-O$_2$ plasma through combined experiments and simulation

abstract:
  High density polyethylene surfaces were exposed to the atmospheric
post-discharge of a radiofrequency plasma torch supplied in helium and oxygen.
Dynamic water contact angle measurements were performed to evaluate changes in
surface hydrophilicity and angle resolved x-ray photoelectron spectroscopy was
carried out to identify the functional groups responsible for wettability
changes and to study their subsurface depth profiles, up to 9 nm in depth. The
reactions leading to the formation of C-O, C=O and O-C=O groups were simulated
by molecular dynamics. These simulations demonstrate that impinging oxygen
atoms do not react immediately upon impact but rather remain at or close to the
surface before eventually reacting. The simulations also explain the release of
gaseous species in the ambient environment as well as the ejection of low
molecular weight oxidized materials from the surface.


title:
Competitive and synergistic effects between excimer VUV radiation and O
  radicals on the etching mechanisms of polyethylene and fluoropolymer surfaces
  treated by atmospheric He-O$_2$ post-discharge

abstract:
  Among various surface modification techniques, plasma can be used as a source
for tailoring the surface properties of diverse materials. HDPE and
fluoropolymer surfaces have been treated by the post-discharge of an
atmospheric RF-plasma torch supplied with helium and oxygen gases. The
plasma-treated surfaces were characterized by measurements of mass losses,
water contact angles, x-ray photoelectron spectroscopy and atomic force
microscopy. This experimental approach correlated with an optical
characterization of the plasma phase allowed us to propose etching mechanisms
occurring at the post-discharge/polymer interface. We discuss how competitive
and synergistic effects can result from the oxidation and/or the roughening of
the surface but also from the excimer VUV radiation, the He metastable species
and the O radicals reaching the plasma-polymer interface.


title: Decomposition of exact pfd persistence bimodules

abstract:
  We characterize the class of persistence modules indexed over $\mathbb{R}^2$
that are decomposable into summands whose support have the shape of a {\em
block}---i.e. a horizontal band, a vertical band, an upper-right quadrant, or a
lower-left quadrant. Assuming the modules are pointwise finite dimensional
(pfd), we show that they are decomposable into block summands if and only if
they satisfy a certain local property called {\em exactness}. Our proof follows
the same scheme as the proof of decomposition for pfd persistence modules
indexed over $\mathbb{R}$, yet it departs from it at key stages due to the
product order on $\mathbb{R}^2$ not being a total order, which leaves some
important gaps open. These gaps are filled in using more direct arguments. Our
work is motivated primarily by the stability theory for zigzags and
interlevel-sets persistence modules, in which block-decomposable bimodules play
a key part. Our results allow us to drop some of the conditions under which
that theory holds, in particular the Morse-type conditions.


title: A Mathematical Model of the Rainwater Flows in a Green Roof

abstract:
  A model is presented for the gravity-driven flow of rainwater descending
through the soil layer of a green roof, treated as a porous medium on a flat
permeable surface representing an efficient drainage layer. A fully saturated
zone is shown to occur. It is typically a thin layer, relative to the total
soil thickness, and lies at the bottom of the soil layer. This provides a
bottom boundary condition for the partially saturated upper zone. It is shown
that after the onset of rainfall, well-defined fronts of water can descend
through the soil layer. Also the rainwater flow is relatively quick compared
with the moisture uptake by the roots of the plants in the roof. In separate
models the exchanges of water are described between the (smaller-scale) porous
granules of soil, the roots and the rainwater in the inter-granule pores.


title: Differential expansion and rectangular HOMFLY for the figure eight knot

abstract:
  Differential expansion (DE) for a Wilson loop average in representation $R$
is built to respect degenerations of representations for small groups. At the
same time it behaves nicely under some changes of the loop, e.g. of some knots
in the case of $3d$ Chern-Simons theory. Especially simple is the relation
between the DE for the trefoil $3_1$ and for the figure eight knot $4_1$. Since
arbitrary colored HOMFLY for the trefoil are known from the Rosso-Jones
formula, it is therefore enough to find their DE in order to make a conjecture
for the figure eight. We fulfil this program for all rectangular representation
$R=[r^s]$, i.e. make a plausible conjecture for the rectangularly colored
HOMFLY of the figure eight knot, which generalizes the old result for totally
symmetric and antisymmetric representations.


title: Quantum Image Matching

abstract:
  Quantum image processing (QIP) means the quantum based methods to speed up
image processing algorithms. Many quantum image processing schemes claim that
their efficiency are theoretically higher than their corresponding classical
schemes. However, most of them do not consider the problem of measurement. As
we all know, measurement will lead to collapse. That is to say, executing the
algorithm once, users can only measure the final state one time. Therefore, if
users want to regain the results (the processed images), they must execute the
algorithms many times and then measure the final state many times to get all
the pixels' values. If the measurement process is taken into account, whether
or not the algorithms are really efficient needs to be reconsidered. In this
paper, we try to solve the problem of measurement and give a quantum image
matching algorithm. Unlike most of the QIP algorithms, our scheme interests
only one pixel (the target pixel) instead of the whole image. It modifies the
probability of pixels based on Grover's algorithm to make the target pixel to
be measured with higher probability, and the measurement step is executed only
once. An example is given to explain the algorithm more vividly. Complexity
analysis indicates that the quantum scheme's complexity is $O(2^{n})$ in
contradistinction to the classical scheme's complexity $O(2^{2n+2m})$, where
$m$ and $n$ are integers related to the size of images.


title:
Dynamic atmospheres and winds of cool luminous giants, I. Al$_2$O$_3$
  and silicate dust in the close vicinity of M-type AGB stars

abstract:
  High spatial resolution techniques have given valuable insights into the mass
loss mechanism of AGB stars, which presumably involves a combination of
atmospheric levitation by pulsation-induced shock waves and radiation pressure
on dust. Observations indicate that Al$_2$O$_3$ condenses at distances of about
2 stellar radii or less, prior to the formation of silicates. Al$_2$O$_3$
grains are therefore prime candidates for producing the scattered light
observed in the close vicinity of several M-type AGB stars, and they may be
seed particles for the condensation of silicates at lower temperatures. We have
constructed a new generation of Dynamic Atmosphere & Radiation-driven Wind
models based on Implicit Numerics (DARWIN), including a time-dependent
treatment of grain growth & evaporation for both Al$_2$O$_3$ and Fe-free
silicates (Mg$_2$SiO$_4$). The equations describing these dust species are
solved in the framework of a frequency-dependent radiation-hydrodynamical model
for the atmosphere & wind structure, taking pulsation-induced shock waves and
periodic luminosity variations into account. Condensation of Al$_2$O$_3$ at the
close distances and in the high concentrations implied by observations requires
high transparency of the grains in the visual and near-IR region to avoid
destruction by radiative heating. For solar abundances, radiation pressure due
to Al$_2$O$_3$ is too low to drive a wind. Nevertheless, this dust species may
have indirect effects on mass loss. The formation of composite grains with an
Al$_2$O$_3$ core and a silicate mantle can give grain growth a head start,
increasing both mass loss rates and wind velocities. Furthermore, our
experimental core-mantle grain models lead to variations of visual and near-IR
colors during a pulsation cycle which are in excellent agreement with
observations.


title: Remarks on Asymptotic Symmetries and the Sub-leading Soft Photon Theorem

abstract:
  A deep connection has been recently established between soft theorems and
symmetries at null infinity in gravity and gauge theories, recasting the former
as Ward identities of the latter. In particular, different orders (in the
frequency of the soft particle) in the soft theorems are believed to be
controlled by different asymptotic symmetries. In this paper we argue that this
needs not be the case by focusing on the soft photon theorem. We argue that the
sub-leading soft factor follows from the same symmetry responsible for the
leading one, namely certain residual (large) gauge transformations of the gauge
theory. In particular, expanding the associated charge in inverse powers of the
radial coordinate, the (sub-)leading charge yields the (sub-)leading soft
factor.


title: The ISW effect and the lack of large-angle CMB temperature correlations

abstract:
  It is by now well established that the magnitude of the two-point
angular-correlation function of the cosmic microwave background temperature
anisotropies is anomalously low for angular separations greater than about 60
degrees. Physics explanations of this anomaly typically focus on the properties
of the Universe at the surface of last scattering, relying on the fact that
large-angle temperature fluctuations are dominated by the Sachs-Wolfe effect
(SW). However, these fluctuations also receive important contributions from the
integrated Sachs-Wolfe effect (ISW) at both early (eISW) and late ($\ell$ISW)
times. Here we study the correlations in those large-angle temperature
fluctuations and their relative contributions to $S_{1/2}$ -- the standard
measure of the correlations on large angular scales. We find that in the
best-fitting $\Lambda$CDM cosmology, while the auto-correlation of the early
contributions (SW plus eISW) dominates $S_{1/2}$, there are also significant
contributions originating from cross-terms between the early and late
contributions. In particular, realizations of $\Lambda$CDM with low $S_{1/2}$
are typically produced from a combination of somewhat low pure-early
correlations and accidental cancellations among early-late correlations. We
also find that if the pure $\ell$ISW auto-correlations were the only
contribution to $S_{1/2}$ in $\Lambda$CDM, then the $p$-value of the observed
cut-sky $S_{1/2}$ would be unremarkable. This suggests that physical mechanisms
operating only at or near the last scattering surface could explain the
observed lack of large-angle correlations, though this is not the typical
resolution within $\Lambda$CDM.


title: Condorcet-Consistent and Approximately Strategyproof Tournament Rules

abstract:
  We consider the manipulability of tournament rules for round-robin
tournaments of $n$ competitors. Specifically, $n$ competitors are competing for
a prize, and a tournament rule $r$ maps the result of all $\binom{n}{2}$
pairwise matches (called a tournament, $T$) to a distribution over winners.
Rule $r$ is Condorcet-consistent if whenever $i$ wins all $n-1$ of her matches,
$r$ selects $i$ with probability $1$.
  We consider strategic manipulation of tournaments where player $j$ might
throw their match to player $i$ in order to increase the likelihood that one of
them wins the tournament. Regardless of the reason why $j$ chooses to do this,
the potential for manipulation exists as long as $\Pr[r(T) = i]$ increases by
more than $\Pr[r(T) = j]$ decreases. Unfortunately, it is known that every
Condorcet-consistent rule is manipulable (Altman and Kleinberg). In this work,
we address the question of how manipulable Condorcet-consistent rules must
necessarily be - by trying to minimize the difference between the increase in
$\Pr[r(T) = i]$ and decrease in $\Pr[r(T) = j]$ for any potential manipulating
pair.
  We show that every Condorcet-consistent rule is in fact $1/3$-manipulable,
and that selecting a winner according to a random single elimination bracket is
not $\alpha$-manipulable for any $\alpha > 1/3$. We also show that many
previously studied tournament formats are all $1/2$-manipulable, and the
popular class of Copeland rules (any rule that selects a player with the most
wins) are all in fact $1$-manipulable, the worst possible. Finally, we consider
extensions to match-fixing among sets of more than two players.


title:
Compact E+A Galaxies as a Progenitor of Massive Compact Quiescent
  Galaxies at 0.2<z< 0.8

abstract:
  We search the Sloan Digital Sky Survey and the Baryon Oscillation Sky Survey
to identify ~5500 massive compact quiescent galaxy candidates at 0.2<z<0.8. We
robustly classify a subsample of 438 E+A galaxies based on their spectral
properties and make this catalog publicly available. We examine sizes, stellar
population ages and kinematics of galaxies in the sample and show that the
physical properties of compact E+A galaxies suggest that they are a progenitor
of massive compact quiescent galaxies. Thus, two classes of objects-compact E+A
and compact quiescent galaxies-may be linked by a common formation scenario.
The typical stellar population age of compact E+A galaxies is <1 Gyr. The
existence of compact E+A galaxies with young stellar populations at 0.2<z<0.8
means that some compact quiescent galaxies first appear at intermediate
redshifts. We derive a lower limit for the number density of compact E+A
galaxies. Assuming passive evolution, we convert this number density into an
appearance rate of new compact quiescent galaxies at 0.2<z<0.8. The lower limit
number density of compact quiescent galaxies which may appear at z<0.8 is
comparable to the lower limit of the total number density of compact quiescent
galaxies at these intermediate redshifts. Thus, a substantial fraction of the
z<0.8 massive compact quiescent galaxy population may descend from compact E+A
galaxies at intermediate redshifts.


title:
Information Theoretically Aided Reinforcement Learning for Embodied
  Agents

abstract:
  Reinforcement learning for embodied agents is a challenging problem. The
accumulated reward to be optimized is often a very rugged function, and
gradient methods are impaired by many local optimizers. We demonstrate, in an
experimental setting, that incorporating an intrinsic reward can smoothen the
optimization landscape while preserving the global optimizers of interest. We
show that policy gradient optimization for locomotion in a complex morphology
is significantly improved when supplementing the extrinsic reward by an
intrinsic reward defined in terms of the mutual information of time consecutive
sensor readings.


title:
Trigonometric and elliptic Ruijsenaars-Schneider systems on the complex
  projective space

abstract:
  We present a direct construction of compact real forms of the trigonometric
and elliptic $n$-particle Ruijsenaars-Schneider systems whose completed
center-of-mass phase space is the complex projective space $\mathbb{CP}^{n-1}$
with the Fubini-Study symplectic structure. These systems are labelled by an
integer $p\in\{1,\dots,n-1\}$ relative prime to $n$ and a coupling parameter
$y$ varying in a certain punctured interval around $p\pi/n$. Our work extends
Ruijsenaars's pioneering study of compactifications that imposed the
restriction $0<y<\pi/n$, and also builds on an earlier derivation of more
general compact trigonometric systems by Hamiltonian reduction.


title: 3D Printed Stencils for Texturing Flat Surfaces

abstract:
  We address the problem of texturing flat surfaces by spray-painting through
3D printed stencils. We propose a system that (1) decomposes an image into
alpha-blended layers; (2) computes a stippling given a transparency channel;
(3) generates a 3D printed stencil given a stippling and (4) simulates the
effects of spray-painting through the stencil.


title: The First Focused Hard X-ray Images of the Sun with NuSTAR

abstract:
  We present results from the the first campaign of dedicated solar
observations undertaken by the \textit{Nuclear Spectroscopic Telescope ARray}
({\em NuSTAR}) hard X-ray telescope. Designed as an astrophysics mission, {\em
NuSTAR} nonetheless has the capability of directly imaging the Sun at hard
X-ray energies ($>$3~keV) with an increase in sensitivity of at least two
magnitude compared to current non-focusing telescopes. In this paper we
describe the scientific areas where \textit{NuSTAR} will make major
improvements on existing solar measurements. We report on the techniques used
to observe the Sun with \textit{NuSTAR}, their limitations and complications,
and the procedures developed to optimize solar data quality derived from our
experience with the initial solar observations. These first observations are
briefly described, including the measurement of the Fe K-shell lines in a
decaying X-class flare, hard X-ray emission from high in the solar corona, and
full-disk hard X-ray images of the Sun.


title: Path Planning for Cooperative Routing of Air-Ground Vehicles

abstract:
  We consider a cooperative vehicle routing problem for surveillance and
reconnaissance missions with communication constraints between the vehicles. We
propose a framework which involves a ground vehicle and an aerial vehicle; the
vehicles travel cooperatively satisfying the communication limits, and visit a
set of targets. We present a mixed integer linear programming (MILP)
formulation and develop a branch-and-cut algorithm to solve the path planning
problem for the ground and air vehicles. The effectiveness of the proposed
approach is corroborated through extensive computational experiments on several
randomly generated instances.


title: Two Generalizations of the Wedderburn-Artin Theorem with Applications

abstract:
  We say that an $R$-module $M$ is {\it virtually simple} if $M\neq (0)$ and
$N\cong M$ for every non-zero submodule $N$ of $M$, and {\it virtually
semisimple} if each submodule of $M$ is isomorphic to a direct summand of $M$.
We carry out a study of virtually semisimple modules and modules which are
direct sums of virtually simple modules. Our theory provides two natural
generalizations of the Wedderburn-Artin Theorem and an analogous to the
classical Krull-Schmidt Theorem. Some applications of these theorems are
indicated. For instance, it is shown that the following statements are
equivalent for a ring $R$: (i) Every finitely generated left (right)
$R$-modules is virtually semisimple; (ii) Every finitely generated left (right)
$R$-modules is a direct sum of virtually simple modules; (iii)
$R\cong\prod_{i=1}^{k} M_{n_i}(D_i)$ where $k, n_1,\ldots,n_k\in \Bbb{N}$ and
each $D_i$ is a principal ideal V-domain; and {\rm (iv)} Every non-zero
finitely generated left $R$-module can be written uniquely (up to isomorphism
and order of the factors) in the form $ Rm_1 \oplus\ldots\oplus Rm_k$ where
each $Rm_i$ is either a simple $R$-module or a left virtually simple direct
summand of $R$.


title:
Long tailed trions in monolayer MoS$_2$: Temperature dependent asymmetry
  and red-shift of trion photoluminescence spectra

abstract:
  Monolayer molybdenum disulfide (MoS$_2$) has emerged as an excellent 2D model
system because of its two inequivalent, direct-gap valleys that lead to exotic
bound and excited states. Here we focus on one such bound state, the negatively
charged trion. Unlike excitons, trions can radiatively decay with non-zero
momentum by kicking out an electron, resulting in an asymmetric trion
photoluminescence (PL) peak with a long low-energy tail. As a consequence, the
peak position does not correspond to the zero momentum trion energy. By
including the trion's long tail in our analysis we are able to accurately
separate the exciton from the trion contributions to the PL spectra. According
to theory, the asymmetric energy tail has both a size-dependent and a
temperature-dependent contribution. Analysis of the temperature-dependent data
reveals the effective trion size, consistent with literature, and the
temperature dependence of the band gap and spin-orbit splitting of the valence
band. Finally, we observe signatures of Pauli-blocking of the trion decay.


title:
Constraint on a cosmological variation in the proton-to-electron mass
  ratio from electronic CO absorption

abstract:
  Carbon monoxide (CO) absorption in the sub-damped Lyman-$\alpha$ absorber at
redshift $z_{abs} \simeq 2.69$, toward the background quasar SDSS
J123714.60+064759.5 (J1237+0647), was investigated for the first time in order
to search for a possible variation of the proton-to-electron mass ratio, $\mu$,
over a cosmological time-scale. The observations were performed with the Very
Large Telescope/Ultraviolet and Visual Echelle Spectrograph with a
signal-to-noise ratio of 40 per 2.5 kms$^{-1}$ per pixel at $\sim 5000$ \AA.
Thirteen CO vibrational bands in this absorber are detected: the A$^{1}\Pi$ -
X$^{1}\Sigma^{+}$ ($\nu'$,0) for $\nu' = 0 - 8$, B$^{1}\Sigma^{+}$ -
X$^{1}\Sigma^{+}$ (0,0), C$^{1}\Sigma^{+}$ - X$^{1}\Sigma^{+}$ (0,0), and
E$^{1}\Pi$ - X$^{1}\Sigma^{+}$ (0,0) singlet-singlet bands and the
d$^{3}\Delta$ - X$^{1}\Sigma^{+}$ (5,0) singlet-triplet band. An updated
database including the most precise molecular inputs needed for a
$\mu$-variation analysis is presented for rotational levels $J = 0 - 5$,
consisting of transition wavelengths, oscillator strengths, natural lifetime
damping parameters, and sensitivity coefficients to a variation of the
proton-to-electron mass ratio. A comprehensive fitting method was used to fit
all the CO bands at once and an independent constraint of $\Delta\mu/\mu = (0.7
\pm 1.6_{stat} \pm 0.5_{syst}) \times 10^{-5}$ was derived from CO only. A
combined analysis using both molecular hydrogen and CO in the same J1237+0647
absorber returned a final constraint on the relative variation of
$\Delta\mu/\mu = (-5.6 \pm 5.6_{stat} \pm 3.1_{syst}) \times 10^{-6}$, which is
consistent with no variation over a look-back time of $\sim 11.4$ Gyrs.


title: R-parity Violating Supersymmetry at IceCube

abstract:
  The presence of $R$-parity violating (RPV) supersymmetric interactions
involving high-energy neutrinos can lead to resonant production of TeV-scale
squarks inside large-volume neutrino detectors. Using the ultra-high energy
neutrino events observed recently at the IceCube, with the fact that for a
given power-law flux of astrophysical neutrinos, there is no statistically
significant deviation in the current data from the Standard Model expectations,
we derive robust upper limits on the RPV couplings as a function of the
resonantly-produced squark mass, independent of the other unknown model
parameters, as long as the squarks decay dominantly to 2-body final states
involving leptons and quarks through the RPV couplings. With more statistics,
we expect these limits to be comparable/complementary to the existing limits
from direct collider searches and other low-energy processes.


title: Quasilinear SPDEs via rough paths

abstract:
  We are interested in (uniformly) parabolic PDEs with a nonlinear dependance
of the leading-order coefficients, driven by a rough right hand side. For
simplicity, we consider a space-time periodic setting with a single spatial
variable: \begin{equation*} \partial_2u -P( a(u)\partial_1^2u - \sigma(u)f ) =0
  \end{equation*} where $P$ is the projection on mean-zero functions, and $f$
is a distribution and only controlled in the low regularity norm of $
C^{\alpha-2}$ for $\alpha > \frac{2}{3}$ on the parabolic H\"older scale.
  The example we have in mind is a random forcing $f$ and our assumptions
allow, for example, for an $f$ which is white in the time variable $x_2$ and
only mildly coloured in the space variable $x_1$; any spatial covariance
operator $(1 + |\partial_1|)^{-\lambda_1 }$ with $\lambda_1 > \frac13$ is
admissible.
  On the deterministic side we obtain a $C^\alpha$-estimate for $u$, assuming
that we control products of the form $v\partial_1^2v$ and $vf$ with $v$ solving
the constant-coefficient equation $\partial_2 v-a_0\partial_1^2v=f$. As a
consequence, we obtain existence, uniqueness and stability with respect to $(f,
vf, v \partial_1^2v)$ of small space-time periodic solutions for small data. We
then demonstrate how the required products can be bounded in the case of a
random forcing $f$ using stochastic arguments.
  For this we extend the treatment of the singular product $\sigma(u)f$ via a
space-time version of Gubinelli's notion of controlled rough paths to the
product $a(u)\partial_1^2u$, which has the same degree of singularity but is
more nonlinear since the solution $u$ appears in both factors. The PDE
ingredient mimics the (kernel-free) Krylov-Safanov approach to ordinary
Schauder theory.


title:
The Clustering of Galaxies in the Completed SDSS-III Baryon Oscillation
  Spectroscopic Survey: Cosmic Flows and Cosmic Web from Luminous Red Galaxies

abstract:
  We present a Bayesian phase-space reconstruction of the cosmic large-scale
matter density and velocity fields from the SDSS-III Baryon Oscillations
Spectroscopic Survey Data Release 12 (BOSS DR12) CMASS galaxy clustering
catalogue. We rely on a given $\Lambda$CDM cosmology, a mesh resolution in the
range of 6-10 $h^{-1}$ Mpc, and a lognormal-Poisson model with a redshift
dependent nonlinear bias. The bias parameters are derived from the data and a
general renormalised perturbation theory approach. We use combined Gibbs and
Hamiltonian sampling, implemented in the \textsc{argo} code, to iteratively
reconstruct the dark matter density field and the coherent peculiar velocities
of individual galaxies, correcting hereby for coherent redshift space
distortions (RSD). Our tests relying on accurate $N$-body based mock galaxy
catalogues, show unbiased real space power spectra of the nonlinear density
field up to $k\sim0.2\, h$ Mpc$^{-1}$, and vanishing quadrupoles down to
$r\sim20\,h^{-1}$ Mpc. We also demonstrate that the nonlinear cosmic web can be
obtained from the tidal field tensor based on the Gaussian component of the
reconstructed density field. We find that the reconstructed velocities have a
statistical correlation coefficient compared to the true velocities of each
individual lightcone mock galaxy of $r\sim0.68$ including about 10% of
satellite galaxies with virial motions (about $r=0.75$ without satellites). The
power spectra of the velocity divergence agree well with theoretical
predictions up to $k\sim0.2\,h\,{\rm Mpc}^{-1}$. This work will be especially
useful to improve, e.g. BAO reconstructions, kinematic Sunyaev-Zeldovich (kSZ),
integrated Sachs-Wolfe (ISW) measurements, or environmental studies.


title:
Universal deformation rings for a class of self-injective special
  biserial algebras

abstract:
  Let $\mathbf{k}$ be an algebraically closed field of arbitrary
characteristic, let $\Lambda$ be a finite dimensional $\mathbf{k}$-algebra and
let $V$ be a $\Lambda$-module with stable endomorphism ring isomorphic to
$\mathbf{k}$. If $\Lambda$ is self-injective, then $V$ has a universal
deformation ring $R(\Lambda,V)$, which is a complete local commutative
Noetherian $\mathbf{k}$-algebra with residue field $\mathbf{k}$. Moreover, if
$\Lambda$ is further a Frobenius $\mathbf{k}$-algebra, then $R(\Lambda,V)$ is
stable under syzygies. We use these facts to determine the universal
deformation rings of string $\Lambda_{m,N}$-modules whose corresponding stable
endomorphism ring is isomorphic to $\mathbf{k}$, and which lie either in a
connected component of the stable Auslander-Reiten quiver of $\Lambda_{m,N}$
containing a module with endomorphism ring isomorphic to $\mathbf{k}$ or in a
periodic component containing only string $\Lambda_{m,N}$-modules, where $m\geq
3$ and $N\geq 1$ are integers, and $\Lambda_{m,N}$ is a self-injective special
biserial $\mathbf{k}$-algebra.


title:
Non-perturbative BRST quantization of Euclidean Yang-Mills theories in
  Curci-Ferrari gauges

abstract:
  In this paper we address the issue of the non-perturbative quantization of
Euclidean Yang-Mills theories in the Curci-Ferrari gauge. In particular, we
construct a Refined Gribov-Zwanziger action for this gauge which takes into
account the presence of gauge copies as well as the dynamical formation of
dimension two condensates. This action enjoys a non-perturbative BRST symmetry
recently proposed in \cite{Capri:2015ixa}. Finally, we give attention to the
gluon propagator in different space-time dimensions.


title:
Betti categories of graded modules and applications to monomial ideals
  and toric rings

abstract:
  We introduce the notion of Betti category for graded modules over suitably
graded polynomial rings, and more generally for modules over certain small
categories. Our categorical approach allows us to treat simultaneously many
important cases, such as monomial ideals and toric rings. We prove that in
these cases the Betti category is a finite combinatorial object that completely
determines the structure of the minimal free resolution. For monomial ideals,
the Betti category is the same as the Betti poset that we studied in a previous
article. We describe in detail and with examples how the theory applies to the
toric case, and provide an analog for toric rings of the lcm-lattice for
monomial ideals.


title: Matroid multiple cyclic exchange property

abstract:
  We prove a new exchange property for bases of a matroid that generalizes the
multiple symmetric exchange property. For every bases $B_1,\dots,B_k$ of a
matroid and a subset $A_1\subset B_1$ there exist subsets $A_2\subset
B_2,\dots,A_k\subset B_k$ such that all sets $(B_i\setminus A_i)\cup A_{i-1}$
achieved by a cyclic shift of $A_i$'s by one are bases.


title:
Nonconvex penalization of switching control of partial differential
  equations

abstract:
  This paper is concerned with optimal control problems for parabolic partial
differential equations with pointwise in time switching constraints on the
control. A standard approach to treat constraints in nonlinear optimization is
penalization, in particular using $L^1$-type norms. Applying this approach to
the switching constraint leads to a nonsmooth and nonconvex
infinite-dimensional minimization problem which is challenging both
analytically and numerically. Adding $H^1$ regularization or restricting to a
finite-dimensional control space allows showing existence of optimal controls.
First-order necessary optimality conditions are then derived using tools of
nonsmooth analysis. Their solution can be computed using a combination of
Moreau-Yosida regularization and a semismooth Newton method. Numerical examples
illustrate the properties of this approach.


title: An adaptive interpolation scheme for molecular potential energy surfaces

abstract:
  The calculation of potential energy surfaces for quantum dynamics can be a
time consuming task -- especially when a high level of theory for the
electronic structure calculation is required. We propose an adaptive
interpolation algorithm based on polyharmonic splines combined with a partition
of unity approach. The adaptive node refinement allows to greatly reduce the
number of sample points by employing a local error estimate. The algorithm and
its scaling behavior is evaluated for a model function in 2, 3 and 4
dimensions. The developed algorithm allows for a more rapid and reliable
interpolation of a potential energy surface within a given accuracy compared to
the non-adaptive version.


title:
Phonon spectrum and correlations in a transonic flow of an atomic Bose
  gas

abstract:
  Motivated by a recent experiment of J.~Steinhauer, we reconsider the spectrum
and the correlations of the phonons spontaneously emitted in stationary
transonic flows. The latter are described by "waterfall" configurations which
form a one-parameter family of stable flows. For parameters close to their
experimental values, in spite of high gradients near the sonic horizon, the
spectrum is accurately planckian in the relevant frequency domain, where the
temperature differs from the relativistic prediction by less than $10 \%$. We
then study the density correlations across the horizon and the non-separable
character of the final state. We show that the relativistic expressions provide
accurate approximations when the initial temperature is not too high. We also
show that the phases of the scattering coefficients introduce a finite shift of
the location of the correlations which was so far overlooked. This shift is due
to the asymmetry of the flow across the horizon, and persists in the
dispersion-less regime. Finally we show how the formation of the sonic horizon
modifies both local and non-local density correlations.


title:
PerfEnforce: A Dynamic Scaling Engine for Analytics with Performance
  Guarantees

abstract:
  In this paper, we present PerfEnforce, a scaling engine designed to enable
cloud providers to sell performance levels for data analytics cloud services.
PerfEnforce scales a cluster of virtual machines allocated to a user in a way
that minimizes cost while probabilistically meeting the query runtime
guarantees offered by a service level agreement. With PerfEnforce, we show how
to scale a cluster in a way that minimally disrupts a user's query session. We
further show when to scale the cluster using one of three methods: feedback
control, reinforcement learning, or perceptron learning. We find that
perceptron learning outperforms the other two methods when making cluster
scaling decisions.


title: Family of Subharmonic Functions and Separately Subharmonic Functions

abstract:
  We prove that the upper envelope of a family of subharmonic functions defined
on an open subset of $\mathbb{R}^{N}$, $(N\geq2)$, that is finite every where,
is locally bounded above outside a closed nowhere dense set with no bounded
components. Then we conclude as a consequence that a separately subharmonic
function is subharmonic outside a closed nowhere dense set with no bounded
components. It generalizes a result due to Cegrell and Sadullaev.


title:
Exact form of the exponential Foldy-Wouthuysen transformation operator
  for an arbitrary-spin particle

abstract:
  The exact exponential Foldy-Wouthuysen transformation operator applicable for
a particle with an arbitrary spin is derived. It can be successfully utilized
for verifying any Foldy-Wouthuysen transformation method based on the
exponential operator. When a verified method is relativistic, the relativistic
exponential operator should be expanded in the semirelativistic power series.
The use of the obtained exponential operator for a derivation of the
Foldy-Wouthuysen Hamiltonian makes it possible to check the validity of any
other method of the Foldy-Wouthuysen transformation, while this possibility may
need a greater computational effort.


title:
Studies of the Origin of High-Frequency Quasi-Periodic Oscillations of
  Mass Accreting Black Holes in X-ray Binaries with Next-Generation X-ray
  Telescopes

abstract:
  Observations with RXTE (Rossi X-ray Timing Explorer) revealed the presence of
High Frequency Quasi-Periodic Oscillations (HFQPOs) of the X-ray flux from
several accreting stellar mass Black Holes. HFQPOs (and their counterparts at
lower frequencies) may allow us to study general relativity in the strong
gravity regime. However, the observational evidence today does not yet allow us
to distinguish between different HFQPO models. In this paper we use a general
relativistic ray-tracing code to investigate X-ray timing-spectroscopy and
polarization properties of HFQPOs in the orbiting Hotspot model. We study
observational signatures for the particular case of the 166 Hz quasi-periodic
oscillation (QPO) in the galactic binary GRS 1915+105. We conclude with a
discussion of the observability of spectral signatures with a
timing-spectroscopy experiment like the LOFT (Large Observatory for X-ray
Timing) and polarization signatures with space-borne X-ray polarimeters such as
IXPE (Imaging X-ray Polarimetry Explorer), PolSTAR (Polarization Spectroscopic
Telescope Array), PRAXyS (Polarimetry of Relativistic X-ray Sources), or XIPE
(X-ray Imaging Polarimetry Explorer). A high count-rate mission like LOFT would
make it possible to get a QPO phase for each photon, enabling the study of the
QPO-phase-resolved spectral shape and the correlation between this and the flux
level. Owing to the short periods of the HFQPOs, first-generation X-ray
polarimeters would not be able to assign a QPO phase to each photon. The study
of QPO-phase-resolved polarization energy spectra would thus require
simultaneous observations with a first-generation X-ray polarimeter and a
LOFT-type mission.


title: Towards ontology driven learning of visual concept detectors

abstract:
  The maturity of deep learning techniques has led in recent years to a
breakthrough in object recognition in visual media. While for some specific
benchmarks, neural techniques seem to match if not outperform human judgement,
challenges are still open for detecting arbitrary concepts in arbitrary videos.
In this paper, we propose a system that combines neural techniques, a large
scale visual concepts ontology, and an active learning loop, to provide on the
fly model learning of arbitrary concepts. We give an overview of the system as
a whole, and focus on the central role of the ontology for guiding and
bootstrapping the learning of new concepts, improving the recall of concept
detection, and, on the user end, providing semantic search on a library of
annotated videos.


title: Selective Trapping of DNA using Glass Microcapillaries

abstract:
  We show experimentally that a cheap glass microcapillary can accumulate
{\lambda}-phage DNA at its tip and deliver the DNA into the capillary using a
combination of electro-osmotic flow, pressure-driven flow, and electrophoresis.
We develop an efficient simulation model for this phenomenon based on the
electrokinetic equations and the finite-element method. Using our model, we
explore the large parameter space of the trapping mechanism by varying the salt
concentration, the capillary surface charge, the applied voltage, the pressure
difference, and the mobility of the analyte molecules. Our simulation results
show that this system can be tuned to capture a wide range of analyte
molecules, such as DNA or proteins, based on their electrophoretic mobility.
Our method for separation and pre-concentration of analytes has implications
for the development of low-cost lab-on-a-chip devices.


title: Fast Zero-Shot Image Tagging

abstract:
  The well-known word analogy experiments show that the recent word vectors
capture fine-grained linguistic regularities in words by linear vector offsets,
but it is unclear how well the simple vector offsets can encode visual
regularities over words. We study a particular image-word relevance relation in
this paper. Our results show that the word vectors of relevant tags for a given
image rank ahead of the irrelevant tags, along a principal direction in the
word vector space. Inspired by this observation, we propose to solve image
tagging by estimating the principal direction for an image. Particularly, we
exploit linear mappings and nonlinear deep neural networks to approximate the
principal direction from an input image. We arrive at a quite versatile tagging
model. It runs fast given a test image, in constant time w.r.t.\ the training
set size. It not only gives superior performance for the conventional tagging
task on the NUS-WIDE dataset, but also outperforms competitive baselines on
annotating images with previously unseen tags


title:
Long-range Ordering of Topological Excitations in a Two-Dimensional
  Superfluid Far From Equilibrium

abstract:
  We study the relaxation of a 2D ultracold Bose-gas from a nonequilibrium
initial state containing vortex excitations in experimentally realizable square
and rectangular traps. We show that the subsystem of vortex gas excitations
results in the spontaneous emergence of a coherent superfluid flow with a
non-zero coarse-grained vorticity field. The streamfunction of this emergent
quasi-classical 2D flow is governed by a Boltzmann-Poisson equation. This
equation reveals that maximum entropy states of a neutral vortex gas that
describe the spectral condensation of energy can be classified into types of
flow depending on whether or not the flow spontaneously acquires angular
momentum. Numerical simulations of a neutral point vortex model and a Bose gas
governed by the 2D Gross-Pitaevskii equation in a square reveal that a large
scale monopole flow field with net angular momentum emerges that is consistent
with predictions of the Boltzmann-Poisson equation. The results allow us to
characterise the spectral energy condensate in a 2D quantum fluid that bears
striking similarity with similar flows observed in experiments of 2D classical
turbulence. By deforming the square into a rectangular region, the resulting
maximum entropy state switches to a dipolar flow field with zero net angular
momentum.


title: A characterization of combinatorial demand

abstract:
  We prove that combinatorial demand functions are characterized by two
properties: continuity and the law of demand.


title:
Energy-conserving time-discretisation of abstract dynamic problems with
  applications in continuum mechanics of solids

abstract:
  An abstract 2nd-order evolution equation or inclusion is discretised in time
in such a way that the energy is conserved at least in qualified cases,
typically in the cases when the governing energy is component-wise quadratic or
"slightly-perturbed" quadratic. Specific applications in continuum mechanics of
solids possibly with various internal variables cover vibrations or waves in
linear viscoelastic materials at small strains, coupled with some inelastic
processes as plasticity, damage, or phase transformations, and also some
surface variants related to contact mechanics. The applicability is illustrated
by numerical simulations of vibrations interacting with a frictional contact or
waves emitted by an adhesive contact of a 2-dimensional viscoelastic body.


title: On conservation laws of Navier-Stokes Galerkin discretizations

abstract:
  We study conservation properties of Galerkin methods for the incompressible
Navier-Stokes equations, without the divergence constraint strongly enforced.
In typical discretizations such as the mixed finite element method, the
conservation of mass is enforced only weakly, and this leads to discrete
solutions which may not conserve energy, momentum, angular momentum, helicity,
or vorticity, even though the physics of the Navier-Stokes equations dictate
that they should. We aim in this work to construct discrete formulations that
conserve as many physical laws as possible without utilizing a strong
enforcement of the divergence constraint, and doing so leads us to a new
formulation that conserves each of energy, momentum, angular momentum,
enstrophy in 2D, helicity and vorticity (for reference, the usual convective
formulation does not conserve most of these quantities). Several numerical
experiments are performed, which verify the theory and test the new
formulation.


title:
The role of electron and phonon temperatures in the helicity-independent
  all-optical switching of GdFeCo

abstract:
  Ultrafast optical heating of the electrons in ferrimagnetic metals can result
in all-optical switching (AOS) of the magnetization. Here we report
quantitative measurements of the temperature rise of GdFeCo thin films during
helicity-independent AOS. Critical switching fluences are obtained as a
function of the initial temperature of the sample and for laser pulse durations
from 55 fs to 15 ps. We conclude that non-equilibrium phenomena are necessary
for helicity-independent AOS, although the peak electron temperature does not
play a critical role. Pump-probe time-resolved experiments show that the
switching time increases as the pulse duration increases, with 10 ps pulses
resulting in switching times of ~sim 13 ps. These results raise new questions
about the fundamental mechanism of helicity-independent AOS.


title:
Global existence for a bulk/surface model for active-transport-induced
  polarisation in biological cells

abstract:
  We consider a coupled bulk/surface model for advection and diffusion of
interacting chemical species in biological cells. Specifically, we consider a
signalling protein that can exist in both a cytosolic and a membrane-bound
state, along with a variable that gives a coarse-grained description of the
cytoskeleton. The main focus of our work is on the well-posedness of the model,
whereby the coupling at the boundary is the main source of analytical
difficulty. A priori $L^p$-estimates, together with classical Schauder theory,
deliver global existence of classical solutions for small data on bounded,
Lipschitz domains. For two physically reasonable regularised versions of the
boundary coupling, we are able to prove global existence of solutions for
arbitrary data. In addition, we prove the existence of a family of steady-state
solutions of the main model which are parametrised by the total mass of the
membrane-bound signal molecule.


abstract:
  In this paper we study the behaviour of the Igusa-Todorov functions for Artin
algebras A with finite injective dimension, and Gorenstein algebras as a
particular case. We show that the $\phi$-dimension and $\psi$-dimension are
finite in both cases. Also we prove that monomial, gentle and cluster tilted
algebras have finite $\phi$-dimension and finite $\psi$-dimension.


title: High energy density in the collision of $N$ kinks in the $\phi^4$ model

abstract:
  Recently for the sine-Gordon equation it has been established that during
collisions of $N$ slow kinks maximal energy density increases as $N^2$. In this
numerical study, the same scaling rule is established for the non-integrable
$\phi^4$ model for $N\le 5$. For odd (even) $N$ the maximal energy density is
in the form of potential (kinetic) energy density. Maximal elastic strain is
also calculated. In addition, the effect of the kink's internal modes on the
maximal energy density is analysed for $N=1, 2, 3$. Our results suggest that in
multi-soliton collisions very high energy density can be achieved in a
controllable manner.


title: Measurement of the $CP$ asymmetry in $B_s^0-\overline{B}{}_s^0$ mixing

abstract:
  The $CP$ asymmetry in the mixing of $B_s^0$ and $\overline{B}{}_s^0$ mesons
is measured in proton-proton collision data corresponding to an integrated
luminosity of 3.0 fb$^{-1}$, recorded by the LHCb experiment at centre-of-mass
energies of 7 and 8 TeV. Semileptonic $B_s^0$ and $\overline{B}{}_s^0$ decays
are studied in the inclusive mode $D_s^{\mp} \mu^{\pm} \nu_{\mu} X$ with the
$D_s^{\mp}$ mesons reconstructed in the $K^+ K^- \pi^{\mp}$ final state.
Correcting the observed charge asymmetry for detection and background effects,
the $CP$ asymmetry is found to be $a_{\text{sl}}^s = (0.39 \pm 0.26 \pm 0.20)
\% $, where the first uncertainty is statistical and the second systematic.
This is the most precise measurement of $a_{\text{sl}}^s$ to date. It is
consistent with the prediction from the Standard Model and will constrain new
models of particle physics.


title:
Towards Usable openEHR-aware Clinical Decision Support: A User-centered
  Design Approach

abstract:
  This thesis addresses the question of how usable openEHR-aware clinical
decision support can be designed and developed in order to improve the quality
of health care. To answer this research question, several sub-questions were
identified and investigated. This included analyzing state of the art in two
different aspects of design and development and evaluation of Clinical Decision
Support (CDS) and also investigating application of a customized user-centered
design (UCD) process in developing openEHR-based clinical applications.
Analysis of state of the art in interplay between Human-Computer Interaction
(HCI) and CDS and also the intersection between CDS and Electronic Health
Records (EHR) revealed that consideration of both HCI and integration of CDS
into EHR is more appreciated in theory than in practice and there is still a
long way to go before reaching an acceptable level in these two success factors
of CDS. Moreover, the experience in designing an openEHR-based clinical
application revealed that apart from benefits offered by openEHR approach, such
as specifying different roles and involvement of domain experts in defining
domain concepts, there are various shortcomings that need to be improved, for
instance the limited support for openEHR application developers. Additionally,
this study revealed that there are characteristics of the domain, tasks and
users in the domain that developers should be informed about while applying UCD
methods.


title:
Ultra-long-range dynamic correlations in a microscopic model for aging
  gels

abstract:
  We use large-scale computer simulations to explore the non-equilibrium aging
dynamics in a microscopic model for colloidal gels. We find that gelation
resulting from a kinetically-arrested phase separation is accompanied by
`anomalous' particle dynamics revealed by superdiffusive particle motion and
compressed exponential relaxation of time correlation functions.
Spatio-temporal analysis of the dynamics reveals intermittent heterogeneities
producing spatial correlations over extremely large length scales. Our study is
the first microscopically-resolved model reproducing all features of the
spontaneous aging dynamics observed experimentally in soft materials.


title: Security Protocols in a Nutshell

abstract:
  Security protocols are building blocks in secure communications. They deploy
some security mechanisms to provide certain security services. Security
protocols are considered abstract when analyzed, but they can have extra
vulnerabilities when implemented. This manuscript provides a holistic study on
security protocols. It reviews foundations of security protocols, taxonomy of
attacks on security protocols and their implementations, and different methods
and models for security analysis of protocols. Specifically, it clarifies
differences between information-theoretic and computational security, and
computational and symbolic models. Furthermore, a survey on computational
security models for authenticated key exchange (AKE) and password-authenticated
key exchange (PAKE) protocols, as the most important and well-studied type of
security protocols, is provided.


title:
Technical Report: Directed Controller Synthesis of Discrete Event
  Systems

abstract:
  This paper presents a Directed Controller Synthesis (DCS) technique for
discrete event systems. The DCS method explores the solution space for reactive
controllers guided by a domain-independent heuristic. The heuristic is derived
from an efficient abstraction of the environment based on the componentized way
in which complex environments are described. Then by building the composition
of the components on-the-fly DCS obtains a solution by exploring a reduced
portion of the state space. This work focuses on untimed discrete event systems
with safety and co-safety (i.e. reachability) goals. An evaluation for the
technique is presented comparing it to other well-known approaches to
controller synthesis (based on symbolic representation and compositional
analyses).


title: Causal Inference by Quantile Regression Kink Designs

abstract:
  The quantile regression kink design (QRKD) is proposed by empirical
researchers as a potential method to assess heterogeneous treatment effects
under suitable research designs, but its causal interpretation remains unknown.
We propose a causal interpretation of the QRKD estimand. Under flexible
heterogeneity and endogeneity, the QRKD estimand measures a weighted average of
heterogeneous marginal effects at respective conditional quantiles of outcome
given a designed kink point. In addition, we develop weak convergence results
for the QRKD estimator as a local quantile process for the purpose of
conducting statistical inference on heterogeneous treatment effects using the
QRKD. Applying our methods to the Continuous Wage and Benefit History Project
(CWBH) data, we find significantly heterogeneous positive causal effects of
unemployment insurance benefits on unemployment durations in Louisiana between
1981 and 1983. These effects are larger for individuals with longer
unemployment durations.


title: Asynchrony begets Momentum, with an Application to Deep Learning

abstract:
  Asynchronous methods are widely used in deep learning, but have limited
theoretical justification when applied to non-convex problems. We show that
running stochastic gradient descent (SGD) in an asynchronous manner can be
viewed as adding a momentum-like term to the SGD iteration. Our result does not
assume convexity of the objective function, so it is applicable to deep
learning systems. We observe that a standard queuing model of asynchrony
results in a form of momentum that is commonly used by deep learning
practitioners. This forges a link between queuing theory and asynchrony in deep
learning systems, which could be useful for systems builders. For convolutional
neural networks, we experimentally validate that the degree of asynchrony
directly correlates with the momentum, confirming our main result. An important
implication is that tuning the momentum parameter is important when considering
different levels of asynchrony. We assert that properly tuned momentum reduces
the number of steps required for convergence. Finally, our theory suggests new
ways of counteracting the adverse effects of asynchrony: a simple mechanism
like using negative algorithmic momentum can improve performance under high
asynchrony. Since asynchronous methods have better hardware efficiency, this
result may shed light on when asynchronous execution is more efficient for deep
learning systems.


title: Strictly Positive Definite Kernels on a Product of Spheres II

abstract:
  We present, among other things, a necessary and sufficient condition for the
strict positive definiteness of an isotropic and positive definite kernel on
the cartesian product of a circle and a higher dimensional sphere. The result
complements similar results previously obtained for strict positive
definiteness on a product of circles [Positivity, to appear, arXiv:1505.01169]
and on a product of high dimensional spheres [J. Math. Anal. Appl. 435 (2016),
286-301, arXiv:1505.03695].


title:
Waddling Random Walk: Fast and Accurate Mining of Motif Statistics in
  Large Graphs

abstract:
  Algorithms for mining very large graphs, such as those representing online
social networks, to discover the relative frequency of small subgraphs within
them are of high interest to sociologists, computer scientists and marketeers
alike. However, the computation of these network motif statistics via naive
enumeration is infeasible for either its prohibitive computational costs or
access restrictions on the full graph data. Methods to estimate the motif
statistics based on random walks by sampling only a small fraction of the
subgraphs in the large graph address both of these challenges. In this paper,
we present a new algorithm, called the Waddling Random Walk (WRW), which
estimates the concentration of motifs of any size. It derives its name from the
fact that it sways a little to the left and to the right, thus also sampling
nodes not directly on the path of the random walk. The WRW algorithm achieves
its computational efficiency by not trying to enumerate subgraphs around the
random walk but instead using a randomized protocol to sample subgraphs in the
neighborhood of the nodes visited by the walk. In addition, WRW achieves
significantly higher accuracy (measured by the closeness of its estimate to the
correct value) and higher precision (measured by the low variance in its
estimations) than the current state-of-the-art algorithms for mining subgraph
statistics. We illustrate these advantages in speed, accuracy and precision
using simulations on well-known and widely used graph datasets representing
real networks.


title: Local limit of the fixed point forest

abstract:
  Consider the following partial "sorting algorithm" on permutations: take the
first entry of the permutation in one-line notation and insert it into the
position of its own value. Continue until the first entry is 1. This process
imposes a forest structure on the set of all permutations of size $n$, where
the roots are the permutations starting with 1 and the leaves are derangements.
Viewing the process in the opposite direction towards the leaves, one picks a
fixed point and moves it to the beginning. Despite its simplicity, this "fixed
point forest" exhibits a rich structure. In this paper, we consider the fixed
point forest in the limit $n\to \infty$ and show using Stein's method that at a
random permutation the local structure weakly converges to a tree defined in
terms of independent Poisson point processes. We also show that the
distribution of the length of the longest path to a leaf converges to the
geometric distribution with mean $e-1$, and the length of the shortest path
converges to the Poisson distribution with mean 1. In addition, the higher
moments are bounded and hence the expectations converge as well.


title: More about scalar gravity

abstract:
  We discuss a class of models for gravity based on a scalar field. The models
include and generalize the old approach by Nordstr\"om which predated and in
some way inspired General Relativity. The class include also a model that we
have recently introduced and discussed in its cosmological aspects (GSG). We
present here a complete characterisation of the Schwarschild geometry as a
vacuum solution of GSG and sketch a discussion of the first Post-Newtonian
approximation.


title: ObliviSync: Practical Oblivious File Backup and Synchronization

abstract:
  Oblivious RAM (ORAM) protocols are powerful techniques that hide a client's
data as well as access patterns from untrusted service providers. We present an
oblivious cloud storage system, ObliviSync, that specifically targets one of
the most widely-used personal cloud storage paradigms: synchronization and
backup services, popular examples of which are Dropbox, iCloud Drive, and
Google Drive. This setting provides a unique opportunity because the above
privacy properties can be achieved with a simpler form of ORAM called
write-only ORAM, which allows for dramatically increased efficiency compared to
related work. Our solution is asymptotically optimal and practically efficient,
with a small constant overhead of approximately 4x compared with non-private
file storage, depending only on the total data size and parameters chosen
according to the usage rate, and not on the number or size of individual files.
Our construction also offers protection against timing-channel attacks, which
has not been previously considered in ORAM protocols. We built and evaluated a
full implementation of ObliviSync that supports multiple simultaneous read-only
clients and a single concurrent read/write client whose edits automatically and
seamlessly propagate to the readers. We show that our system functions under
high work loads, with realistic file size distributions, and with small
additional latency (as compared to a baseline encrypted file system) when
paired with Dropbox as the synchronization service.