title: X-ray image separation via coupled dictionary learning

abstract:
  In support of art investigation, we propose a new source sepa- ration method
that unmixes a single X-ray scan acquired from double-sided paintings. Unlike
prior source separation meth- ods, which are based on statistical or structural
incoherence of the sources, we use visual images taken from the front- and
back-side of the panel to drive the separation process. The coupling of the two
imaging modalities is achieved via a new multi-scale dictionary learning
method. Experimental results demonstrate that our method succeeds in the
discrimination of the sources, while state-of-the-art methods fail to do so.


title:
Signatures of four-particle correlations associated with exciton-carrier
  interactions in coherent spectroscopy on bulk GaAs

abstract:
  Transient four-wave mixing studies of bulk GaAs under conditions of broad
bandwidth excitation of primarily interband transitions have enabled
four-particle correlations tied to degenerate (exciton-exciton) and
nondegenerate (exciton-carrier) interactions to be studied. Real
two-dimensional Fourier-transform spectroscopy (2DFTS) spectra reveal a complex
response at the heavy-hole exciton emission energy that varies with the
absorption energy, ranging from dispersive on the diagonal, through absorptive
for low-energy interband transitions to dispersive with the opposite sign for
interband transitions high above band gap. Simulations using a multilevel model
augmented by many-body effects provide excellent agreement with the 2DFTS
experiments and indicate that excitation-induced dephasing (EID) and
excitation-induced shift (EIS) affect degenerate and nondegenerate interactions
equivalently, with stronger exciton-carrier coupling relative to
exciton-exciton coupling by approximately an order of magnitude. These
simulations also indicate that EID effects are three times stronger than EIS in
contributing to the coherent response of the semiconductor.


title:
Two-dimensional terahertz magnetic resonance spectroscopy of collective
  spin waves

abstract:
  Nonlinear manipulation of nuclear and electron spins is the basis for all
advanced methods in magnetic resonance including multidimensional nuclear
magnetic and electron spin resonance spectroscopies, magnetic resonance
imaging, and in recent years, quantum control over individual spins. The
methodology is facilitated by the ease with which the regime of strong coupling
can be reached between radiofrequency or microwave magnetic fields and nuclear
or electron spins respectively, typified by sequences of magnetic pulses that
control the magnetic moment directions. The capabilities meet a bottleneck,
however, for far-infrared magnetic resonances characteristic of correlated
electron materials, molecular magnets, and proteins that contain high-spin
transition metal ions. Here we report the development of two-dimensional
terahertz magnetic resonance spectroscopy and its use for direct observation of
the nonlinear responses of collective spin waves (magnons). The spectra show
magnon spin echoes and 2-quantum signals that reveal pairwise correlations
between magnons at the Brillouin zone center. They also show resonance-enhanced
second-harmonic and difference-frequency signals. Our methods are readily
generalizable to multidimensional magnetic resonance spectroscopy and nonlinear
coherent control of terahertz-frequency spin systems in molecular complexes,
biomolecules, and materials.


title: Regression with n$\to$1 by Expert Knowledge Elicitation

abstract:
  We consider regression under the "extremely small $n$ large $p$" condition,
where the number of samples $n$ is so small compared to the dimensionality $p$
that predictors cannot be estimated without prior knowledge. This setup occurs
in personalized medicine, for instance, when predicting treatment outcomes for
an individual patient based on noisy high-dimensional genomics data. A
remaining source of information is expert knowledge, which has received
relatively little attention in recent years. We formulate the inference problem
of asking expert feedback on features on a budget, propose an elicitation
strategy for a simple "small $n$" setting, and derive conditions under which
the elicitation strategy is optimal. Experiments on simulated experts, both on
synthetic and genomics data, demonstrate that the proposed strategy can
drastically improve prediction accuracy.


title: Secretary Problem with quality-based payoff

abstract:
  We consider a variant of the classical Secretary Problem. In this setting,
the candidates are ranked according to some exchangeable random variable and
the quest is to maximize the expected quality of the chosen aspirant. We find
an upper bound for the optimal hiring rule, present examples showing it is
sharp, and recover the classical case, among other results.


title: Extending the Reach of Compressed Gluinos at the LHC

abstract:
  Conventional supersymmetry searches rely on large missing momentum and, on
that account, are unsuitable for discovering superpartners nearly degenerate
with the LSP. Such "compressed regions" are best probed by dedicated strategies
that exploit their unique kinematic features. We consider a case study of a
compressed gluino-bino simplified spectrum, motivated by its ability to set the
dark matter relic abundance via co-annihilation. A kinematic variable suited to
this spectrum is introduced, by which, for a gluino-bino mass splitting of 100
GeV, the discovery reach is extendable to m(gluino) = 850 GeV (1370 GeV) at LHC
center-of-mass energy 8 TeV (13 TeV) with luminosity 20 inverse fb (3000
inverse fb). The non-trivial role played by soft triggers is also discussed.


title:
Recent progress and review of issues related to Physics Dynamics
  Coupling in geophysical models

abstract:
  Geophysical models of the atmosphere and ocean invariably involve
parameterizations. These represent two distinct areas: Subgrid processes that
the model cannot resolve, and diabatic sources in the equations, due to
radiation for example. Hence, coupling between these physics parameterizations
and the resolved fluid dynamics and also between the dynamics of the air and
water, is necessary. In this paper weather and climate models are used to
illustrate the problems. Nevertheless the same applies to other geophysical
models. This coupling is an important aspect of geophysical models. However,
often model development is strictly segregated into either physics or dynamics.
As a consequence, this area has many unanswered questions. Recent developments
in the design of dynamical cores, extended process physics and predicted future
changes of the computational infrastructure are increasing complexity. This
paper reviews the state-of-the-art of the physics-dynamics coupling in
geophysical models, surveys the analysis techniques, and illustrates open
questions in this field. This paper focuses on two objectives: To illustrate
the phenomenology of the coupling problem with references to examples in the
literature and to show how the problem can be analysed. Proposals are made on
how to advance the understanding and upcoming challenges with emerging modeling
strategies. This paper is of interest to model developers who aim to improve
the models and have to make choices on and test new implementations, to users
who have to understand choices presented to them and finally users of outputs,
who have to distinguish physical features from numerical problems in the model
data.


title: The Sphere Covering Inequality and Its Applications

abstract:
  In this paper, we show that the total area of two distinct surfaces with
Gaussian curvature equal to 1, which are also conformal to the Euclidean unit
disk with the same conformal factor on the boundary, must be at least 4{\pi}.
In other words, the areas of these surfaces must cover the whole unit sphere
after a proper rearrangement. We refer to this lower bound of total area as the
Sphere Covering Inequality. The inequality and its generalizations are applied
to a number of open problems related to Moser- Trudinger type inequalities,
mean field equations and Onsager vortices, etc, and yield optimal results.


title: Volatility Forecasts Using Nonlinear Leverage Effects

abstract:
  The leverage effect-- the correlation between an asset's return and its
volatility-- has played a key role in forecasting and understanding volatility
and risk. While it is a long standing consensus that leverage effects exist and
improve forecasts, empirical evidence paradoxically do not show that most
individual stocks exhibit this phenomena, mischaracterizing risk and therefore
leading to poor predictive performance. We examine this paradox, with the goal
to improve density forecasts, by relaxing the assumption of linearity in the
leverage effect. Nonlinear generalizations of the leverage effect are proposed
within the Bayesian stochastic volatility framework in order to capture
flexible leverage structures, where small fluctuations in prices have a
different effect from large shocks. Efficient Bayesian sequential computation
is developed and implemented to estimate this effect in a practical, on-line
manner. Examining 615 stocks that comprise the S\&P500 and Nikkei 225, we find
that relaxing the linear assumption to our proposed nonlinear leverage effect
function improves predictive performances for 89\% of all stocks compared to
the conventional model assumption.


title:
Simple DRAM and Virtual Memory Abstractions to Enable Highly Efficient
  Memory Systems

abstract:
  In most modern systems, the memory subsystem is managed and accessed at
multiple different granularities at various resources. We observe that such
multi-granularity management results in significant inefficiency in the memory
subsystem. Specifically, we observe that 1) page-granularity virtual memory
unnecessarily triggers large memory operations, and 2) existing cache-line
granularity memory interface is inefficient for performing bulk data operations
and operations that exhibit poor spatial locality. To address these problems,
we present a series of techniques in this thesis.
  First, we propose page overlays, a framework augments the existing virtual
memory framework with the ability to track a new version of a subset of cache
lines within each virtual page. We show that this extension is powerful by
demonstrating its benefits on a number of applications.
  Second, we show that DRAM can be used to perform more complex operations than
just store data. We propose RowClone, a mechanism to perform bulk data copy and
initialization completely inside DRAM, and Buddy RAM, a mechanism to perform
bulk bitwise operations using DRAM. Both these techniques achieve an
order-of-magnitude improvement in the efficiency of the respective operations.
  Third, we propose Gather-Scatter DRAM, a technique that exploits DRAM
organization to effectively gather/scatter values with a power-of-2 strided
access patterns. For these access patterns, GS-DRAM achieves near-ideal
bandwidth and cache utilization, without increasing the latency of fetching
data from memory.
  Finally, we propose the Dirty-Block Index, a new way of tracking dirty
blocks. In addition to improving the efficiency of bulk data coherence, DBI has
several applications including high-performance memory scheduling, efficient
cache lookup bypassing, and enabling heterogeneous ECC.


title: P-adic Line Integrals and Cauchy's Theorems

abstract:
  Working in the p-adic analog of the complex numbers, we'll define a line
integral on a small arc of a circle. This allows new versions of the Residue
Theorem, the Cauchy-Goursat Theorem on discs with and without holes, Cauchy's
Integral Formula and the Z-P Theorem. In contrast to results in complex
analysis, these integrals allow the points on a boundary circle, the bulk of a
p-adic disc, to be treated the same as points interior to the boundary circle.
The theory of the integral is developed, especially for functions holomorphic
on an open disc, and integrals will be calculated for rational functions,
Krasner analytic functions and some well-known functions that are not Krasner
analytic. Some computations will produce values of Kubota-Leopoldt L-functions
at ordinary integers.


title: Multicolour Poisson Matching

abstract:
  Consider several independent Poisson point processes on R^d, each with a
different colour and perhaps a different intensity, and suppose we are given a
set of allowed family types, each of which is a multiset of colours such as
red-blue or red-red-green. We study translation-invariant schemes for
partitioning the points into families of allowed types. This generalizes the
1-colour and 2-colour matching schemes studied previously (where the sets of
allowed family types are the singletons {red-red} and {red-blue} respectively).
We characterize when such a scheme exists, as well as the optimal tail
behaviour of a typical family diameter. The latter has two different regimes
that are analogous to the 1-colour and 2-colour cases, and correspond to the
intensity vector lying in the interior and boundary of the existence region
respectively.
  We also address the effect of requiring the partition to be a deterministic
function (i.e. a factor) of the points. Here we find the optimal tail behaviour
in dimension 1. There is a further separation into two regimes, governed by
algebraic properties of the allowed family types.


title: Using Read-$k$ Inequalities to Analyze a Distributed MIS Algorithm

abstract:
  Until recently, the fastest distributed MIS algorithm, even for simple
graphs, e.g., unoriented trees has been the simple randomized algorithm
discovered the 80s. This algorithm (commonly called Luby's algorithm) computes
an MIS in $O(\log n)$ rounds (with high probability). This situation changed
when Lenzen and Wattenhofer (PODC 2011) presented a randomized $O(\sqrt{\log
n}\cdot \log\log n)$-round MIS algorithm for unoriented trees. This algorithm
was improved by Barenboim et al. (FOCS 2012), resulting in an $O(\sqrt{\log n
\cdot \log\log n})$-round MIS algorithm.
  The analyses of these tree MIS algorithms depends on "near independence" of
probabilistic events, a feature of the tree structure of the network. In their
paper, Lenzen and Wattenhofer hope that their algorithm and analysis could be
extended to graphs with bounded arboricity. We show how to do this. By using a
new tail inequality for read-k families of random variables due to Gavinsky et
al. (Random Struct Algorithms, 2015), we show how to deal with dependencies
induced by the recent tree MIS algorithms when they are executed on bounded
arboricity graphs. Specifically, we analyze a version of the tree MIS algorithm
of Barenboim et al. and show that it runs in $O(\mbox{poly}(\alpha) \cdot
\sqrt{\log n \cdot \log\log n})$ rounds in the $\mathcal{CONGEST}$ model for
graphs with arboricity $\alpha$.
  While the main thrust of this paper is the new probabilistic analysis via
read-$k$ inequalities, for small values of $\alpha$, this algorithm is faster
than the bounded arboricity MIS algorithm of Barenboim et al. We also note that
recently (SODA 2016), Gaffari presented a novel MIS algorithm for general
graphs that runs in $O(\log \Delta) + 2^{O(\sqrt{\log\log n})}$ rounds; a
corollary of this algorithm is an $O(\log \alpha + \sqrt{\log n})$-round MIS
algorithm on arboricity-$\alpha$ graphs.


title: Shock fluctuations for the Hammersley process

abstract:
  We consider the Hammersley interacting particle system starting from a shock
initial profile with densities $\lambda,\rho\in\mathbb{R}$ ($\lambda > \rho$).
The microscopic shock is taken as the position of a second-class particle
initially at the origin, and the main results are: a central limit theorem for
the shock; the variance of the shock equals $2[\lambda\rho(\lambda -
\rho)]^{-1}t + O(t^{2/3})$. By using the same method of proof, we also prove
similar results for first-class particles.


title:
Bidirectionality From Cargo Thermal Fluctuations in Motor-Mediated
  Transport

abstract:
  Molecular motor proteins serve as an essential component of intracellular
transport by generating forces to haul cargoes along cytoskeletal filaments.
Two species of motors that are directed oppositely (e.g. kinesin, dynein) can
be attached to the same cargo, which is known to produce bidirectional net
motion. Although previous work focuses on the motor number as the driving noise
source for switching, we propose an alternative mechanism: cargo diffusion. A
mean-field mathematical model of mechanical interactions of two populations of
molecular motors with cargo thermal fluctuations (diffusion) is presented to
study this phenomenon. The delayed response of a motor to fluctuations in the
cargo velocity is quantified, allowing for the reduction of the full model a
single "characteristic distance", a proxy for the net force on the cargo. The
system is then found to be metastable, with switching exclusively due to cargo
diffusion between distinct directional transport states. The time to switch
between these states is then investigated using a mean first passage time
analysis. The switching time is found to be non-monotonic in the drag of the
cargo, providing an experimental test of the theory.

categories: q-bio.SC cond-mat.soft math.DS physics.bio-ph


title: Deep Roots: Improving CNN Efficiency with Hierarchical Filter Groups

abstract:
  We propose a new method for creating computationally efficient and compact
convolutional neural networks (CNNs) using a novel sparse connection structure
that resembles a tree root. This allows a significant reduction in
computational cost and number of parameters compared to state-of-the-art deep
CNNs, without compromising accuracy, by exploiting the sparsity of inter-layer
filter dependencies. We validate our approach by using it to train more
efficient variants of state-of-the-art CNN architectures, evaluated on the
CIFAR10 and ILSVRC datasets. Our results show similar or higher accuracy than
the baseline architectures with much less computation, as measured by CPU and
GPU timings. For example, for ResNet 50, our model has 40% fewer parameters,
45% fewer floating point operations, and is 31% (12%) faster on a CPU (GPU).
For the deeper ResNet 200 our model has 25% fewer floating point operations and
44% fewer parameters, while maintaining state-of-the-art accuracy. For
GoogLeNet, our model has 7% fewer parameters and is 21% (16%) faster on a CPU
(GPU).


title:
Asteroid thermal modeling in the presence of reflected sunlight with an
  application to WISE/NEOWISE observational data

abstract:
  This study addresses thermal modeling of asteroids with a new derivation of
the Near Earth Asteroid Thermal (NEATM) model which correctly accounts for the
presence of reflected sunlight in short wave IR bands. Kirchhoff's law of
thermal radiation applies to this case and has important implications. New
insight is provided into the eta parameter in the NEATM model and it is
extended to thermal models besides NEATM. The role of surface material
properties on eta is examined using laboratory spectra of meteorites and other
asteroid compositional proxies; the common assumption that emissivity e = 0.9
in asteroid thermal models may not be justified and can lead to misestimating
physical parameters. In addition, indeterminacy in thermal modeling can limit
its ability to uniquely determine temperature and other physical properties. A
new curve fitting approach allows thermal modeling to be done independent of
visible band observational parameters such as the absolute magnitude H. These
new thermal modeling techniques are applied to observational data for selected
asteroids from the WISE/NEOWISE mission. The previous NEOWISE analysis assumes
Kirchhoff's law does not apply. It also deviates strongly from established
statistical practice and systematically underestimates the sampling error
inherent in observing potentially irregular asteroids from a finite sample of
observations. As a result, the new analysis finds asteroid diameter and other
physical properties that have large differences from published NEOWISE results,
with greatly increased error estimates. NEOWISE results have a claimed +/-10%
accuracy for diameter estimates, but this is unsupported. ABSTRACT CONTINUED IN
PDF...


title:
Evolutionary mixed games in structured populations: Cooperation and the
  benefits of heterogeneity

abstract:
  Evolutionary games on networks traditionally involve the same game at each
interaction. Here we depart from this assumption by considering mixed games,
where the game played at each interaction is drawn uniformly at random from a
set of two different games. While in well-mixed populations the random mixture
of the two games is always equivalent to the average single game, in structured
populations this is not always the case. We show that the outcome is in fact
strongly dependent on the distance of separation of the two games in the
parameter space. Effectively, this distance introduces payoff heterogeneity,
and the average game is returned only if the heterogeneity is small. For higher
levels of heterogeneity the distance to the average game grows, which often
involves the promotion of cooperation. The presented results support preceding
research that highlights the favorable role of heterogeneity regardless of its
origin, and they also emphasize the importance of the population structure in
amplifying facilitators of cooperation.


title:
Linear-memory and Decomposition-invariant Linearly Convergent
  Conditional Gradient Algorithm for Structured Polytopes

abstract:
  Recently, several works have shown that natural modifications of the
classical conditional gradient method (aka Frank-Wolfe algorithm) for
constrained convex optimization, provably converge with a linear rate when: i)
the feasible set is a polytope, and ii) the objective is smooth and
strongly-convex. However, all of these results suffer from two significant
shortcomings: large memory requirement due to the need to store an explicit
convex decomposition of the current iterate, and as a consequence, large
running-time overhead per iteration, and worst case convergence rate that
depends unfavorably on the dimension.
  In this work we present a new conditional gradient variant and a
corresponding analysis that improves on both of the above shortcomings. In
particular: both memory and computation overheads are only linear in the
dimension. Moreover, in case the optimal solution is sparse, the new
convergence rate replaces a factor which is at least linear in the dimension in
previous works, with a linear dependence on the number of non-zeros in the
optimal solution.
  At the heart of our method, and corresponding analysis, is a novel way to
compute decomposition-invariant away-steps. While our theoretical guarantees do
not apply to any polytope, they apply to several important structured polytopes
that capture central concepts such as paths in graphs, perfect matchings in
bipartite graphs, marginal distributions that arise in structured prediction
tasks, and more. Our theoretical findings are complemented by empirical
evidence which shows that our method delivers state-of-the-art performance.


title: Generic non-trivial resonances for Anosov diffeomorphisms

abstract:
  We study real analytic perturbations of hyperbolic linear automorphisms on
the 2-torus. The Koopman and the transfer operator are nuclear of order 0 when
acting on a suitable Hilbert space. We show the generic existence of
non-trivial Ruelle resonances for both operators. We prove that some of the
perturbations preserve the volume and some of them do not.


title: Cryogenic rf test of the first plasma etched SRF cavity

abstract:
  Plasma etching has a potential to be an alternative processing technology for
superconducting radio frequency (SRF) cavities. An apparatus and a method are
developed for plasma etching of the inner surfaces of SRF cavities. To test the
effect of the plasma etching on the cavity rf performance, a 1497 MHz single
cell SRF cavity is used. The single cell cavity is mechanically polished,
buffer chemically etched afterwards and rf tested at cryogenic temperatures for
a baseline test. This cavity is then plasma processed. The processing was
accomplished by moving axially the inner electrode and the gas flow inlet in a
step-wise manner to establish segmented plasma processing. The cavity is rf
tested afterwards at cryogenic temperatures. The rf test and surface condition
results are presented.


title: Generation of hybrid entanglement between a mirror and a trapped ion

abstract:
  We present a scheme for cavity-assisted generation of hybrid entanglement
between a moving mirror belonging to an optomechanical cavity and a single
trapped ion located inside a second cavity. Due to radiation pressure, it is
possible to entangle the moving mirror with one of the cavity fields. Also, by
tuning the second cavity field with the internal degrees of freedom of the ion,
an entangled state of the cavity field/ion can be independently generated. The
fields leaking from each cavity are then combined in a beam-splitter, and
following the detection of the outgoing photons by conveniently placed
photodetectors, we show that it is possible to generate entangled states of the
moving mirror and the single trapped ion subsystems. In our scheme the
generated states are hybrid entangled states, in the sense that they are
constituted by discrete (Fock) states and continuous variable (coherent)
states.

categories: quant-ph cond-mat.mes-hall physics.atom-ph physics.optics


title:
High-efficiency diphenylsulfon derivatives-based organic light-emitting
  diode exhibiting thermally activated delayed fluorescence

abstract:
  Novel thermally activated delayed fluorescence (TADF) material with diphenyl
sulfone (DPS) as an electron acceptor and 3,6-dimethoxycarbazole (DMOC) and
1,3,6,8-Tetramethyl-9H-carbazole (TMC) as electron donors were investigated
theoretically for a blue organic light emitting diode (OLED) emitter. We
calculate the energies of the first singlet (S1) and first triplet (T1)-excited
states of TADF materials by performing density functional theory (DFT) and
time-dependent DFT (TD-DFT) calculations on the ground state using a dependence
on charge transfer amounts for the optimal Hartree-Fock percentage in the
exchange-correlation of TD-DFT. The calculated {\Delta}EST values of TMC-DPS
(0.094 eV) was smaller than DMOC-DPS (0.386 eV) because of the large dihedral
angles between the donor and accepter moieties. We show that TMC-DPS would have
a suitable blue OLED emitter, because it has a large dihedral angle that
creates a small spatial overlap between the HOMO and the LUMO and,
consequently, the small {\Delta}EST and the emission wavelength of 2.82 eV
(439.9 nm).


title:
Theoretical study of asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched
  organic sensitizer for Dye-sensitized solar cells

abstract:
  An asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched organic dye (dye1) with
a cyanoacrylic acid and an indolinum carboxyl acid as electron acceptors and a
triphenylamine as an electron donor was designed and theoretically investigated
for dye-sensitized solar cells (DSSCs). Dye1 was compared to reference
well-known dyes with single electron acceptors (D5 and JYL-SQ6). Density
functional theory and time-dependent density functional theory calculations
were used to estimate the photovoltaic properties of the dyes. Due to the
different lowest unoccupied molecular orbital levels of each acceptor and the
energy antenna of the dual electron donor (D-{\pi}-D), the absorption spectrum
of each branch displayed different shapes. Considering the overall properties,
the asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched organic dye exhibited
high conversion efficiency performance for DSSCs. The findings of this work
suggest that optimizing the branch of electron donors and acceptors in dye
sensitizers based on asymmetric A-{\pi}-D-{\pi}-D-{\pi}-A' tribranched organic
dye produces good photovoltaic properties for DSSCs.


title:
Free fermions on a piecewise linear four-manifold. I: Exotic chain
  complex

abstract:
  Recently, an algebraic realization of the four-dimensional Pachner move 3--3
was found in terms of Grassmann--Gaussian exponentials, and a remarkable
nonlinear parameterization for it, going in terms of a $\mathbb C$-valued
2-cocycle. Here we define, for a given triangulated four-dimensional manifold
and a 2-cocycle on it, an `exotic' chain complex intimately related to the
mentioned parameterization, thus providing a basis for algebraic realizations
of all four-dimensional Pachner moves.


title: Theory of graphene saturable absorption

abstract:
  Saturable absorption is a non-perturbative nonlinear optical phenomenon that
plays a pivotal role in the generation of ultrafast light pulses. Here we show
that this effect emerges in graphene at unprecedentedly low light intensities,
thus opening avenues to new nonlinear physics and applications in optical
technology. Specifically, we theoretically investigate saturable absorption in
extended graphene by developing a non-perturbative single-particle approach,
describing conduction-electron dynamics in the atomically-thin material using
the two-dimensional Dirac equation for massless Dirac fermions, which is recast
in the form of generalized Bloch equations. By solving the electron dynamics
non-perturbatively, we account for both interband and intraband contributions
to the intensity-dependent saturated conductivity and conclude that the former
dominates regardless of the intrinsic doping state of the material. The results
are in excellent agreement with atomistic quantum-mechanical simulations
including higher-band effects. Additionally, we find that the modulation depth
of saturable absorption in graphene can be electrically manipulated through an
externally applied gate voltage. Our results are relevant for the development
of graphene-based optoelectronic devices, as well as for applications in
mode-locking and random lasers.


title:
The BaLROG project - II. Quantifying the influence of bars on the
  stellar populations of nearby galaxies

abstract:
  We continue the exploration of the BaLROG (Bars in Low Redshift Optical
Galaxies) sample: 16 large mosaics of barred galaxies observed with the
integral field unit SAURON. We quantify the influence of bars on the
composition of the stellar component. We derive linestrength indices of
H${\beta}$, Fe5015 and Mgb. Based on single stellar population (SSP) models, we
calculate ages, metallicities and [Mg/Fe] abundances and their gradients along
the bar major and minor axes. The high spatial resolution of our data allows us
to identify breaks among index and SSP profiles, commonly at 0.13$\pm$0.06 bar
length, consistent with kinematic features. Inner gradients are about ten times
steeper than outer gradients and become larger when there is a central rotating
component, implying that the gradients are not independent of dynamics and
orbits. Central ages appear to be younger for stronger bars. Yet, the bar
regions are usually old. We find a flattening of the iron (Fe5015) and
magnesium (Mgb) outer gradients along the bar major axis, translating into a
flattening of the metallicity gradient. This gradient is found to be
0.03$\pm$0.07 dex/kpc along the bar major axis while the mean value of the bar
minor axis compares well with that of an unbarred control sample and is
significantly steeper, namely -0.20$\pm$0.04 dex/kpc. These results confirm
recent simulations and discern the important localized influence of bars. The
elevated [Mg/Fe] abundances of bars and bulges compared to the lower values of
discs suggest an early formation, in particular for early type galaxies.


title: Analytic Representations of Yang-Mills Amplitudes

abstract:
  Scattering amplitudes in Yang-Mills theory can be represented in the
formalism of Cachazo, He and Yuan (CHY) as integrals over an auxiliary
projective space---fully localized on the support of the scattering equations.
Because solving the scattering equations is difficult and summing over the
solutions algebraically complex, a method of directly integrating the terms
that appear in this representation has long been sought. We solve this
important open problem by first rewriting the terms in a manifestly
Mobius-invariant form and then using monodromy relations (inspired by analogy
to string theory) to decompose terms into those for which combinatorial rules
of integration are known. The result is a systematic procedure to obtain
analytic, covariant forms of Yang-Mills tree-amplitudes for any number of
external legs and in any number of dimensions. As examples, we provide compact
analytic expressions for amplitudes involving up to six gluons of arbitrary
helicities.


title:
Updated constraints on velocity and momentum-dependent asymmetric dark
  matter

abstract:
  We present updated constraints on dark matter models with momentum-dependent
or velocity-dependent interactions with nuclei, based on direct detection and
solar physics. We improve our previous treatment of energy transport in the
solar interior by dark matter scattering, leading to significant changes in
fits to many observables. Based on solar physics alone, DM with a
spin-independent $q^{4}$ coupling provides the best fit to data, and a
statistically satisfactory solution to the solar abundance problem. Once direct
detection limits are accounted for however, the best solution is spin-dependent
$v^2$ scattering with a reference cross-section of 10$^{-35}$ cm$^2$ (at a
reference velocity of $v_0=220$ km s$^{-1}$), and a dark matter mass of about 5
GeV.


title: Massive relic galaxies prefer dense environments

abstract:
  We study the preferred environments of $z \sim 0$ massive relic galaxies
($M_\star \gtrsim 10^{10}~\mathrm{M_\odot}$ galaxies with little or no growth
from star formation or mergers since $z \sim 2$). Significantly, we carry out
our analysis on both a large cosmological simulation and an observed galaxy
catalogue.
  Working on the Millennium I-WMAP7 simulation we show that the fraction of
today massive objects which have grown less than 10 per cent in mass since $z
\sim 2$ is ~0.04 per cent for the whole massive galaxy population with $M_\star
> 10^{10}~\mathrm{M_\odot}$. This fraction rises to ~0.18 per cent in galaxy
clusters, confirming that clusters help massive galaxies remain unaltered.
Simulations also show that massive relic galaxies tend to be closer to cluster
centres than other massive galaxies.
  Using the New York University Value-Added Galaxy Catalogue, and defining
relics as $M_\star \gtrsim 10^{10}~\mathrm{M_\odot}$ early-type galaxies with
colours compatible with single-stellar population ages older than 10 Gyr, and
which occupy the bottom 5-percentile in the stellar mass-size distribution, we
find $1.11 \pm 0.05$ per cent of relics among massive galaxies. This fraction
rises to $2.4 \pm 0.4$ per cent in high-density environments.
  Our findings point in the same direction as the works by Poggianti et al. and
Stringer et al. Our results may reflect the fact that the cores of the clusters
are created very early on, hence the centres host the first cluster members.
Near the centres, high-velocity dispersions and harassment help cluster core
members avoid the growth of an accreted stellar envelope via mergers, while a
hot intracluster medium prevents cold gas from reaching the galaxies,
inhibiting star formation.


title:
A Case for Radio Galaxies as the Sources of IceCube's Astrophysical
  Neutrino Flux

abstract:
  We present an argument that radio galaxies (active galaxies with mis-aligned
jets) are likely to be the primary sources of the high-energy astrophysical
neutrinos observed by IceCube. In particular, if the gamma-ray emission
observed from radio galaxies is generated through the interactions of
cosmic-ray protons with gas, these interactions can also produce a population
of neutrinos with a flux and spectral shape similar to that measured by
IceCube. We present a simple physical model in which high-energy cosmic rays
are confined within the volumes of radio galaxies, where they interact with gas
to generate the observed diffuse fluxes of neutrinos and gamma rays. In
addition to simultaneously accounting for the observations of Fermi and
IceCube, radio galaxies in this model also represent an attractive class of
sources for the highest energy cosmic rays.


title:
Spatial Correlation Between Dust and H$\alpha$ Emission in Dwarf
  Irregular Galaxies

abstract:
  Using a sample of dwarf irregular galaxies selected from the ALFALFA blind
HI-survey and observed using the VIMOS IFU, we investigate the relationship
between H$\alpha$ emission and Balmer optical depth ($\tau_{\text{b}}$). We
find a positive correlation between H$\alpha$ luminosity surface density and
Balmer optical depth in 8 of 11 at $\geq$ 0.8$\sigma$ significance (6 of 11 at
$\geq$ 1.0$\sigma$) galaxies. Our spaxels have physical scales ranging from 30
to 80 pc, demonstrating that the correlation between these two variables
continues to hold down to spatial scales as low as 30 pc. Using the Spearman's
rank correlation coefficient to test for correlation between
$\Sigma_{\text{H}\alpha}$ and $\tau_{\text{b}}$ in all the galaxies combined,
we find $\rho = 0.39$, indicating a positive correlation at 4$\sigma$
significance. Our low stellar-mass galaxy results are in agreement with
observations of emission line regions in larger spiral galaxies, indicating
that this relationship is independent of the size of the galaxy hosting the
emission line region. The positive correlation between H$\alpha$ luminosity and
Balmer optical depth within spaxels is consistent with the hypothesis that
young star-forming regions are surrounded by dusty birth-clouds.


title: Short-baseline neutrino oscillations, Planck, and IceCube

abstract:
  We examine a framework with light new physics, which couples to the Standard
Model only via neutrino mixing. Taking the hints from the short-baseline
anomalies seriously and combining them with modern cosmological data and recent
IceCube measurements, we obtain surprisingly effective constraints on the
hidden force: keV $\lesssim M \lesssim0.3$ GeV for the mediator mass and
$g_{h}>10^{-6}-10^{-3}$ for the coupling constant. Flavor equilibration between
the hidden and active neutrinos can be delayed until temperatures of $\sim 1$
MeV, but not below $\sim 100$ keV. This scenario can be tested with
next-generation Cosmic Microwave Background, IceCube, and oscillation
experiments.


title:
Revisiting the Lyman Continuum Escape Crisis: Predictions for z > 6 from
  Local Galaxies

abstract:
  The intrinsic escape fraction of ionizing Lyman continuum photons ($f_{esc}$)
is crucial to understand whether galaxies are capable of reionizing the neutral
hydrogen in the early universe at z>6. Unfortunately, it is not possible to
access $f_{esc}$ at z>4 with direct observations and the handful of
measurements from low redshift galaxies consistently find $f_{esc}$ < 10%,
while at least $f_{esc}$ ~ 10% is necessary for galaxies dominate reionization.
Here, we present the first empirical prediction of $f_{esc}$ at z>6 by
combining the (sparsely populated) relation between [OIII]/[OII] and $f_{esc}$
with the redshift evolution of [OIII]/[OII] as predicted from local high-z
analogs selected by their H$\alpha$ equivalent-width. We find $f_{esc}$ =
$5.7_{-3.3}^{+8.3}$% at z=6 and $f_{esc}$ = $10.4_{-6.3}^{+15.5}$% at z=9 for
galaxies with log(M/M$_{sun}$) ~ 9.0 (errors given as 1$\sigma$). However,
there is a negative correlation with stellar mass and we find up to 50% larger
$f_{esc}$ per 0.5 dex decrease in stellar mass. The population averaged escape
fraction increases according to $f_{esc}$ = $f_{esc,0} ((1+z)/3)^a$, with
$f_{esc,0} = 2.3 \pm 0.05$% and $a=1.17 \pm 0.02$ at z > 2 for log(M/M$_{sun}$)
~ 9.0. With our empirical prediction of $f_{esc}$ (thus fixing an important
previously unknown variable) and further reasonable assumption on clumping
factor and the production efficiency of Lyman continuum photons, we conclude
that the average population of galaxies is just capable to reionize the
universe by z ~ 6.


title:
The rational stable homology of mapping class groups of universal
  nil-manifolds

abstract:
  We compute the rational stable homology of the automorphism groups of free
nilpotent groups. These groups interpolate between the general linear groups
over the ring of integers and the automorphism groups of free groups, and we
employ functor homology to reduce to the abelian case. As an application, we
also compute the rational stable homology of the outer automorphism groups and
of the mapping class groups of the associated aspherical nil-manifolds in the
TOP, PL, and DIFF categories.


title:
Electroweakino pair production at the LHC: NLO SUSY-QCD corrections and
  parton-shower effects

abstract:
  We present a set of NLO SUSY-QCD calculations for the pair production of
neutralinos and charginos at the LHC, and their matching to parton-shower
programs in the framework of the POWHEG-BOX program package. The code we have
developed provides a SUSY Les Houches Accord interface for setting
supersymmetric input parameters. Decays of the neutralinos and charginos and
parton-shower effects can be simulated with PYTHIA. To illustrate the
capabilities of our program, we present phenomenological results for a
representative SUSY parameter point. We find that NLO-QCD corrections increase
the production rates for neutralinos and charginos significantly. The impact of
parton-shower effects on distributions of the weakinos is small, but
non-negligible for jet distributions.


title: The dynamics of z~1 clusters of galaxies from the GCLASS survey

abstract:
  We constrain the internal dynamics of a stack of 10 clusters from the GCLASS
survey at 0.87<z<1.34. We determine the stack cluster mass profile M(r) using
the MAMPOSSt algorithm of Mamon et al., the velocity anisotropy profile beta(r)
from the inversion of the Jeans equation, and the pseudo-phase-space density
profiles Q(r) and Qr(r), obtained from the ratio between the mass density
profile and the third power of the (total and, respectively, radial) velocity
dispersion profiles of cluster galaxies. Several M(r) models are statistically
acceptable for the stack cluster (Burkert, Einasto, Hernquist, NFW). The total
mass distribution has a concentration c=r200/r-2=4.0-0.6+1.0, in agreement with
theoretical expectations, and is less concentrated than the cluster
stellar-mass distribution. The stack cluster beta(r) is similar for passive and
star-forming galaxies and indicates isotropic galaxy orbits near the cluster
center and increasingly radially elongated with increasing cluster-centric
distance. Q(r) and Qr(r) are almost power-law relations with slopes similar to
those predicted from numerical simulations of dark matter halos. Combined with
results obtained for lower-z clusters we determine the dynamical evolution of
galaxy clusters, and compare it with theoretical predictions. We discuss
possible physical mechanisms responsible for the differential evolution of
total and stellar mass concentrations, and of passive and star-forming galaxy
orbits [abridged].


title: A "Universal" Density Profile for the Outer Stellar Halos of Galaxies

abstract:
  The outer stellar halos of galaxies contain vital information about the
formation history of galaxies, since the relaxation timescales in the outskirts
are long enough to keep the memory, while the information about individual
formation events in the central parts has long been lost due to mixing, star
formation and relaxation. To unveil some of the information encoded in these
faint outer halo regions, we study the stellar outskirts of galaxies selected
from a fully hydrodynamical high resolution cosmological simulation, called
Magneticum. We find that the density profiles of the outer stellar halos of
galaxies over a broad mass range can be well described by an Einasto profile.
For a fixed total mass range, the free parameters of the Einasto fits are
closely correlated. Galaxies which had more (dry) merger events tend to have
lesser curved outer stellar halos, however, we find no indication that the
amount of curvature is correlated with galaxy morphology. The Einasto-like
shape of the outer stellar halo densities can also explain the observed
differences between the Milky Way and Andromeda outer stellar halos.


title: Search for Molecular Outflows in Local Volume AGN with Herschel-PACS

abstract:
  We present the results from a systematic search for galactic-scale, molecular
(OH 119 $\mu$m) outflows in a sample of 52 Local Volume ($d < 50$ Mpc) Burst
Alert Telescope detected active galactic nuclei (BAT AGN) with
\emph{Herschel}-PACS. We combine the results from our analysis of the BAT AGN
with the published \emph{Herschel}/PACS data of 43 nearby ($z<0.3$) galaxy
mergers, mostly ultraluminous infrared galaxies (ULIRGs) and QSOs. The objects
in our sample of BAT AGN have, on average, $\sim 10-100$ times lower AGN
luminosities, star formation rates (SFRs), and stellar masses than those of the
ULIRG and QSO sample. OH 119 $\mu$m is detected in 42 of our BAT AGN targets.
Evidence for molecular outflows (i.e. OH absorption profiles with median
velocities more blueshifted than $-$50 km s$^{-1}$ and/or blueshifted wings
with 84-percentile velocities less than $-$300 km s$^{-1}$) is seen in only
four BAT AGN (NGC~7479 is the most convincing case). Evidence for molecular
inflows (i.e. OH absorption profiles with median velocities more redshifted
than 50 km s$^{-1}$) is seen in seven objects, although an inverted P-Cygni
profile is detected unambiguously in only one object (Circinus). Our data show
that both the starburst and AGN contribute to driving OH outflows, but the
fastest OH winds require AGN with quasar-like luminosities. We also confirm
that the total absorption strength of OH 119 $\mu$m is a good proxy for dust
optical depth as it correlates strongly with the 9.7 $\mu$m silicate absorption
feature, a measure of obscuration originating in both the nuclear torus and
host galaxy disk.


title:
Complementarity of DM Searches in a Consistent Simplified Model: the
  Case of Z'

abstract:
  We analyze the constraints from direct and indirect detection on fermionic
Majorana Dark Matter (DM). Because the interaction with the Standard Model (SM)
particles is spin-dependent, a priori the constraints that one gets from
neutrino telescopes, the LHC, direct and indirect detection experiments are
comparable. We study the complementarity of these searches in a particular
example, in which a heavy $Z'$ mediates the interactions between the SM and the
DM. We find that for heavy dark matter indirect detection provides the
strongest bounds on this scenario, while IceCube bounds are typically stronger
than those from direct detection. The LHC constraints are dominant for smaller
dark matter masses. These light masses are less motivated by thermal relic
abundance considerations. We show that the dominant annihilation channels of
the light DM in the Sun and the Galactic Center are either $b\bar b$ or $t\bar
t$, while the heavy DM annihilation is completely dominated by $Zh$ channel.
The latter produces a hard neutrino spectrum which has not been previously
analyzed. We study the neutrino spectrum yielded by DM and recast IceCube
constraints to allow proper comparison with constraints from direct and
indirect detection experiments and LHC exclusions. Note that the original
version of the paper contains an important error: the contribution of the
$Z$-mediated processes was overlooked. This changes some of the results of the
paper. For the details and the correct results please see the erratum attached
to this file as an appendix.


title:
Localization for the Ising model in a transverse field with generic
  aperiodic disorder

abstract:
  We show that the transverse field Ising model undergoes a zero temperature
phase transition for a $G_\delta$ set of ergodic transverse fields. We apply
our results to the special case of quasiperiodic transverse fields, in one
dimension we find a sharp condition for the existence of a phase transition.


title: A Determination of the Charm Content of the Proton

abstract:
  We present an unbiased determination of the charm content of the proton, in
which the charm parton distribution function (PDF) is parametrized on the same
footing as the light quarks and the gluon in a global PDF analysis. This
determination relies on the calculation of deep-inelastic structure functions
in the FONLL scheme, generalized to account for massive charm-initiated
contributions. In contrast to the usual situation in which the charm PDF is
assumed to be generated perturbatively by pair radiation off gluons and light
quarks, vanishing at a scale set by the value of the charm mass m_c, we find
that the fitted charm PDF vanishes within uncertainties at a scale Q~1.5 GeV
for all x<~0.1, independent of the value of m_c used in the coefficient
functions. We also find some evidence that the charm PDF at large x>~0.1 and
low scales does not vanish, but rather has an "intrinsic" component, very
weakly scale dependent and almost independent of the value of m_c, carrying
about 1% of the total momentum of the proton. The uncertainties in all other
PDFs are only slightly increased by the inclusion of fitted charm, while the
dependence of these PDFs on m_c is significantly reduced. When the EMC charm
structure function dataset is included, it is well described by the fit, and
PDF uncertainties in the fitted charm PDF are significantly reduced, though we
verify that excluding the EMC data does not qualitatively modify any of our
findings. The increased stability with respect to m_c persists at high scales
and is the main implication of our results for LHC phenomenology. Fitting the
charm PDF modifies the predictions for processes such as high p_T and large
rapidity charm pair production and Z+c production, and thus we expect that
future LHC data will further constrain the charm content of the proton.


title: Evidence for a CO desorption front in the outer AS 209 disk

abstract:
  Millimeter observations of CO isotopologues are often used to make inferences
about protoplanetary disk gas density and temperature structures. The accuracy
of these estimates depends on our understanding of CO freezeout and desorption
from dust grains. Most models of these processes indicate that CO column
density decreases monotonically with distance from the central star due to a
decrease in gas density and freezeout beyond the CO snowline. We present ALMA
Cycle 2 observations of $^{12}$CO, $^{13}$CO, and C$^{18}$O $J=2-1$ emission
that instead suggest CO enhancement in the outer disk of T Tauri star AS 209.
Most notably, the C$^{18}$O emission consists of a central peak and a ring at a
radius of $\sim1''$ (120 AU), well outside the expected CO snowline. We propose
that the ring arises from the onset of CO desorption near the edge of the
millimeter dust disk. CO desorption exterior to a CO snowline may occur via
non-thermal processes involving cosmic rays or high-energy photons, or via a
radial thermal inversion arising from dust migration.


title: An AO-assisted variability study of four globular clusters

abstract:
  The image subtraction technique applied to study variable stars in globular
clusters represented a leap in the number of new detections, with the drawback
that many of these new light curves could not be transformed to magnitudes due
to the severe crowding. In this paper we present observations of four Galactic
globular clusters, M 2 (NGC 7089), M 10 (NGC 6254), M 80 (NGC 6093) and NGC
1261, taken with the ground-layer adaptive optics module at the SOAR Telescope,
SAM. We show that the higher image quality provided by SAM allows the
calibration of the light curves of the great majority of the variables near the
cores of these clusters as well as the detection of new variables even in
clusters where image-subtraction searches were already conducted. We report the
discovery of 15 new variables in M 2 (12 RR Lyrae stars and 3 SX Phe stars), 12
new variables in M 10 (11 SX Phe and one long-period variable) and one new W
UMa-type variable in NGC 1261. No new detections are found in M 80, but
previous uncertain detections are confirmed and the corresponding light curves
are calibrated into magnitudes. Additionally, based on the number of detected
variables and new HST/UVIS photometry, we revisit a previous suggestion that M
80 may be the globular cluster with the richest population of blue stragglers
in our Galaxy.


title: Thermal Light as a Mixture of Sets of Pulses: the Quasi-1D Example

abstract:
  The relationship between thermal light and coherent pulses is of fundamental
and practical interest. We now know that thermal light cannot be represented as
a statistical mixture of single pulses. In this paper we ask whether or not
thermal light can be represented as a statistical mixture of sets of pulses. We
consider thermal light in a one-dimensional wave-guide, and find a convex
decomposition into products of orthonormal coherent states of localized,
nonmonochromatic modes.


title:
First results from Faint Infrared Grism Survey (FIGS): first
  simultaneous detection of Lyman-alpha emission and Lyman break from a galaxy
  at z=7.51

abstract:
  Galaxies at high redshifts provide a valuable tool to study cosmic dawn, and
therefore it is crucial to reliably identify these galaxies. Here, we present
an unambiguous and first simultaneous detection of both the Lyman-alpha
emission and the Lyman break from a z = 7.512+/- 0.004 galaxy, observed in the
Faint Infrared Grism Survey (FIGS). These spectra, taken with G102 grism on
Hubble Space Telescope (HST), show a significant emission line detection (6
sigma) in multiple observational position angles (PA), with total integrated
Ly{\alpha} line flux of 1.06+/- 0.12 e10-17erg s-1cm-2. The line flux is nearly
a factor of four higher than the previous MOSFIRE spectroscopic observations of
faint Ly{\alpha} emission at {\lambda} = 1.0347{\mu}m, yielding z = 7.5078+/-
0.0004. This is consistent with other recent observations implying that
ground-based near-infrared spectroscopy underestimates total emission line
fluxes, and if confirmed, can have strong implications for reionization studies
that are based on ground-based Lyman-{\alpha} measurements. A 4-{\sigma}
detection of the NV line in one PA also suggests a weak Active Galactic Nucleus
(AGN), potentially making this source the highest-redshift AGN yet found. Thus,
this observation from the Hubble Space Telescope clearly demonstrates the
sensitivity of the FIGS survey, and the capability of grism spectroscopy to
study the epoch of reionization.


title: Plasma electron-hole kinematics: momentum conservation

abstract:
  We analyse the kinematic properties of a plasma electron hole: a non-linear
self-sustained localized positive electric potential perturbation, trapping
electrons, that behaves as a coherent entity. When a hole accelerates or grows
in depth, ion and electron plasma momentum is changed both within the hole and
outside it, by an energization process we call jetting. We present a
comprehensive analytic calculation of the momentum changes of an isolated
general one-dimensional hole. The conservation of the total momentum gives the
hole's kinematics, determining its velocity evolution. Our results explain many
features of the behavior of hole speed observed in numerical simulations,
including self-acceleration at formation, and hole pushing and trapping by ion
streams.


title: Hilbert $C^*$-modules over $\Sigma^*$-algebras

abstract:
  A $\Sigma^*$-algebra is a concrete $C^*$-algebra that is sequentially closed
in the weak operator topology. We study an appropriate class of $C^*$-modules
over $\Sigma^*$-algebras analogous to the class of $W^*$-modules (selfdual
$C^*$-modules over $W^*$-algebras), and we are able to obtain
$\Sigma^*$-versions of virtually all the results in the basic theory of $C^*$-
and $W^*$-modules. In the second half of the paper, we study modules possessing
a weak sequential form of the condition of being countably generated. A
particular highlight of the paper is the "$\Sigma^*$-module completion," a
$\Sigma^*$-analogue of the selfdual completion of a $C^*$-module over a
$W^*$-algebra, which has an elegant uniqueness condition in the countably
generated case.


title: Self-organization of atoms coupled to a chiral reservoir

abstract:
  Tightly confined modes of light, as in optical nanofibers or photonic crystal
waveguides, can lead to large optical coupling in atomic systems, which
mediates long-range interactions between atoms. These one-dimensional systems
can naturally possess couplings that are asymmetric between modes propagating
in different directions. Strong long-range interaction among atoms via these
modes can drive them to a self-organized periodic distribution. In this paper,
we examine the self-organizing behavior of atoms in one dimension coupled to a
chiral reservoir. We determine the solution to the equations of motion in
different parameter regimes, relative to both the detuning of the pump laser
that initializes the atomic dipole-dipole interactions and the degree of
reservoir chirality. In addition, we calculate possible experimental signatures
such as reflectivity from self-organized atoms and motional sidebands.


title: TensorLog: A Differentiable Deductive Database

abstract:
  Large knowledge bases (KBs) are useful in many tasks, but it is unclear how
to integrate this sort of knowledge into "deep" gradient-based learning
systems. To address this problem, we describe a probabilistic deductive
database, called TensorLog, in which reasoning uses a differentiable process.
In TensorLog, each clause in a logical theory is first converted into certain
type of factor graph. Then, for each type of query to the factor graph, the
message-passing steps required to perform belief propagation (BP) are
"unrolled" into a function, which is differentiable. We show that these
functions can be composed recursively to perform inference in non-trivial
logical theories containing multiple interrelated clauses and predicates. Both
compilation and inference in TensorLog are efficient: compilation is linear in
theory size and proof depth, and inference is linear in database size and the
number of message-passing steps used in BP. We also present experimental
results with TensorLog and discuss its relationship to other first-order
probabilistic logics.


title: Quantum Fisher information on two manifolds of two-mode Gaussian states

abstract:
  We investigate two special classes of two-mode Gaussian states of light that
are important from both the experimental and theoretical points of view: the
mode-mixed thermal states and the squeezed thermal ones. Aiming to a parallel
study, we write the Uhlmann fidelity between pairs of states belonging to each
class in terms of their defining parameters. The quantum Fisher information
matrices on the corresponding four-dimensional manifolds are diagonal and allow
insightful parameter estimation. The scalar curvatures of the Bures metric on
both Riemannian manifolds of special two-mode Gaussian states are evaluated and
discussed. They are functions of two variables, namely, the mean numbers of
photons in the incident thermal modes. Our comparative analysis opens the door
to further investigation of the interplay between geometry and statistics for
Gaussian states produced in simple optical devices.


title:
Structure and thermodynamics of a mixture of patchy and spherical
  colloids: a multi-body association theory with complete reference fluid
  information

abstract:
  A mixture of solvent particles with short-range, directional interactions and
solute particles with short-range, isotropic interactions that can bond
multiple times is of fundamental interest in understanding liquids and
colloidal mixtures. Because of multi-body correlations predicting the structure
and thermodynamics of such systems remains a challenge. Earlier Marshall and
Chapman developed a theory wherein association effects due to interactions
multiply the partition function for clustering of particles in a reference
hard-sphere system. The multi-body effects are incorporated in the clustering
process, which in their work was obtained in the absence of the bulk medium.
The bulk solvent effects were then modeled approximately within a second order
perturbation approach. However, their approach is inadequate at high densities
and for large association strengths. Based on the idea that the clustering of
solvent in a defined coordination volume around the solute is related to
occupancy statistics in that defined coordination volume, we develop an
approach to incorporate the complete information about hard-sphere clustering
in a bulk solvent at the density of interest. The occupancy probabilities are
obtained from enhanced sampling simulations but we also develop a concise
parametric form to model these probabilities using the quasichemical theory of
solutions. We show that incorporating the complete reference information
results in an approach that can predict the bonding state and thermodynamics of
the colloidal solute for a wide range of system conditions.


title: Massless and Massive Higher Spins from Anti-de Sitter Space Waveguide

abstract:
  Higgs mechanism to massive higher-spin gauge fields is an outstanding open
problem. We investigate this issue in the context of Kaluza-Klein
compactification. Starting from a free massless higher-spin field in
$(d+2)$-dimensional anti-de Sitter space and compactifying over a finite
angular wedge, we obtain an infinite tower of heavy, light and massless
higher-spin fields in $(d+1)$-dimensional anti-de Sitter space. All massive
higher-spin fields are described gauge invariantly in terms of St\"ueckelberg
fields. The spectrum depends on the boundary conditions imposed at both ends of
the wedges. We obseved that higher-derivative boundary condition is inevitable
for spin greater than three. For some higher-derivative boundary conditions,
equivalently, spectrum-dependent boundary conditions, we get a non-unitary
representation of partially-massless higher-spin fields of varying depth. We
present intuitive picture which higher-derivative boundary conditions yield
non-unitary system in terms of boundary action. We argue that isotropic
Lifshitz interfaces in $O(N)$ Heisenberg magnet or $O(N)$ Gross-Neveu model
provides the holographic dual conformal field theory and propose experimental
test of (inverse) Higgs mechanism for massive and partially massless
higher-spin fields.


title: Generic freeness in frame bundle prolongations of $C^\infty$ actions

abstract:
  Let a real Lie group $G$ act on a $C^\infty$ real manifold $M$. Assume that
the action is $C^\infty$ and that every nontrivial element of $G$ has a nowhere
dense fixpoint set in $M$. We show that, in~some higher order frame bundle $F$
of $M$, there exists a $G$-invariant meager subset $Z$ of $F$ such that the
$G$-action on $F\backslash Z$ is free. A similar result holds for submanifold
jet bundles.


title:
Equivariant Verlinde algebra from superconformal index and
  Argyres-Seiberg duality

abstract:
  In this paper, we show the equivalence between two seemingly distinct 2d
TQFTs: one comes from the "Coulomb branch index" of the class S theory
$T[\Sigma,G]$ on $L(k,1) \times S^1$, the other is the $^LG$ "equivariant
Verlinde formula", or equivalently partition function of $^LG_{\mathbb{C}}$
complex Chern-Simons theory on $\Sigma\times S^1$. We first derive this
equivalence using the M-theory geometry and show that the gauge groups
appearing on the two sides are naturally $G$ and its Langlands dual $^LG$. When
$G$ is not simply-connected, we provide a recipe of computing the index of
$T[\Sigma,G]$ as summation over indices of $T[\Sigma,\tilde{G}]$ with
non-trivial background 't Hooft fluxes, where $\tilde{G}$ is the
simply-connected group with the same Lie algebra. Then we check explicitly this
relation between the Coulomb index and the equivariant Verlinde formula for
$G=SU(2)$ or $SO(3)$. In the end, as an application of this newly found
relation, we consider the more general case where $G$ is $SU(N)$ or $PSU(N)$
and show that equivariant Verlinde algebra can be derived using field theory
via (generalized) Argyres-Seiberg duality. We also attach a Mathematica
notebook that can be used to compute the $SU(3)$ equivariant Verlinde
coefficients.


title: Flow of finite-dimensional algebras

abstract:
  Each finite-dimensional algebra can be identified to the cubic matrix given
by structural constants defining the multiplication between the basis elements
of the algebra. In this paper we introduce the notion of flow (depending on
time) of finite-dimensional algebras. This flow can be considered as a
particular case of (continuous-time) dynamical system whose states are
finite-dimensional algebras with matrices of structural constants satisfying an
analogue of Kolmogorov-Chapman equation. These flows of algebras (FA) can also
be considered as deformations of algebras with the rule (the evolution
equation) given by Kolmogorov-Chapman equation. We mainly use the
multiplications of cubic matrices which were introduced by Maksimov and
consider Kolmogorov-Chapman equation with respect to these multiplications. If
all cubic matrices of structural constants are stochastic (there are several
kinds of stochasticity) then the corresponding FA is called stochastic FA
(SFA). We define SFA generated by known quadratic stochastic processes. For
some multiplications of cubic matrices we reduce Kolmogorov-Chapman equation
given for cubic matrices to the equation given for square matrices. Using this
result many FAs are given (time homogenous, time non-homogenous, periodic,
etc.). For a periodic FA we construct a continuum set of finite-dimensional
algebras and show that the corresponding discrete time FA is dense in the set.
Moreover, we give a construction of an FA which contains algebras of arbitrary
(finite) dimension. For several FAs we describe the time depending behavior
(dynamics) of the properties to be baric, limit algebras, commutative,
evolution algebras or associative algebras.


title: Evolutionary dynamics on any population structure

abstract:
  Evolution occurs in populations of reproducing individuals. The structure of
a biological population affects which traits evolve. Understanding evolutionary
game dynamics in structured populations is difficult. Precise results have been
absent for a long time, but have recently emerged for special structures where
all individuals have the same number of neighbors. But the problem of
determining which trait is favored by selection in the natural case where the
number of neighbors can vary, has remained open. For arbitrary selection
intensity, the problem is in a computational complexity class which suggests
there is no efficient algorithm. Whether there exists a simple solution for
weak selection was unanswered. Here we provide, surprisingly, a general formula
for weak selection that applies to any graph or social network. Our method uses
coalescent theory and relies on calculating the meeting times of random walks.
We can now evaluate large numbers of diverse and heterogeneous population
structures for their propensity to favor cooperation. We can also study how
small changes in population structure---graph surgery---affect evolutionary
outcomes. We find that cooperation flourishes most in societies that are based
on strong pairwise ties.


title: Comments on twisted indices in 3d supersymmetric gauge theories

abstract:
  We study three-dimensional ${\mathcal N}=2$ supersymmetric gauge theories on
${\Sigma_g \times S^1}$ with a topological twist along $\Sigma_g$, a genus-$g$
Riemann surface. The twisted supersymmetric index at genus $g$ and the
correlation functions of half-BPS loop operators on $S^1$ can be computed
exactly by supersymmetric localization. For $g=1$, this gives a simple UV
computation of the 3d Witten index. Twisted indices provide us with a clean
derivation of the quantum algebra of supersymmetric Wilson loops, for any
Yang-Mills-Chern-Simons-matter theory, in terms of the associated Bethe
equations for the theory on ${\mathbb R}^2 \times S^1$. This also provides a
powerful and simple tool to study 3d ${\mathcal N}=2$ Seiberg dualities.
Finally, we study A- and B-twisted indices for ${\mathcal N}=4$ supersymmetric
gauge theories, which turns out to be very useful for quantitative studies of
three-dimensional mirror symmetry. We also briefly comment on a relation
between the $S^2 \times S^1$ twisted indices and the Hilbert series of
${\mathcal N}=4$ moduli spaces.


title: A Posteriori Error Estimation for the p-curl Problem

abstract:
  We derive a posteriori error estimates for a semi-discrete finite element
approximation of a nonlinear eddy current problem arising from applied
superconductivity, known as the $p$-curl problem. In particular, we show the
reliability for non-conforming N\'{e}d\'{e}lec elements based on a residual
type argument and a Helmholtz-Weyl decomposition of
$W^p_0(\text{curl};\Omega)$. As a consequence, we are also able to derive an a
posteriori error estimate for a quantity of interest called the AC loss. The
nonlinearity for this form of Maxwell's equation is an analogue of the one
found in the $p$-Laplacian. It is handled without linearizing around the
approximate solution. The non-conformity is dealt by adapting error
decomposition techniques of Carstensen, Hu and Orlando. Geometric
non-conformities also appear because the continuous problem is defined over a
bounded $C^{1,1}$ domain while the discrete problem is formulated over a weaker
polyhedral domain. The semi-discrete formulation studied in this paper is often
encountered in commercial codes and is shown to be well-posed. The paper
concludes with numerical results confirming the reliability of the a posteriori
error estimate.


title:
Potential mass surveillance and privacy violations in proximity-based
  social applications

abstract:
  Proximity-based social applications let users interact with people that are
currently close to them, by revealing some information about their preferences
and whereabouts. This information is acquired through passive geo-localisation
and used to build a sense of serendipitous discovery of people, places and
interests. Unfortunately, while this class of applications opens different
interactions possibilities for people in urban settings, obtaining access to
certain identity information could lead a possible privacy attacker to identify
and follow a user in their movements in a specific period of time. The same
information shared through the platform could also help an attacker to link the
victim's online profiles to physical identities. We analyse a set of popular
dating application that shares users relative distances within a certain radius
and show how, by using the information shared on these platforms, it is
possible to formalise a multilateration attack, able to identify the user
actual position. The same attack can also be used to follow a user in all their
movements within a certain period of time, therefore identifying their habits
and Points of Interest across the city. Furthermore we introduce a social
attack which uses common Facebook likes to profile a person and finally
identify their real identity.


title:
Emergent non-Hermitian contributions to the Ehrenfest and
  Hellmann-Feynman theorems

abstract:
  We point out that two of the most important theorems of Quantum Mechanics,
the Ehrenfest theorem and the Hellmann-Feynman theorem, lack in their standard
form important information: there are cases where non-Hermitian boundary
contributions emerge. These contributions actually appear naturally, in order
for the above theorems to be valid and applicable (i.e. in multiply-connected
spaces), and this occurs for physical quantities that are not represented by
well-defined self-adjoint operators (such as the position operator in a
periodic potential, or in general Aharonov-Bohm configurations, either in real
or in an arbitrary parameter-space, in the sense of Berry's adiabatic and
cyclic procedures). In this short note, we report modifications of these two
theorems when such non-Hermiticities appear, and we demonstrate how they
resolve certain Quantum Mechanical paradoxes (most of them having been noticed
in the past as violations of the so-called Hypervirial theorem in Quantum
Chemistry). This resolution of paradoxes (essentially the re-establishment of
applicability of the Ehrenfest theorem even in multiply-connected spaces)
always proceeds through the appearance of certain generalized currents, in a
theoretical picture with interesting structure (where a generalized continuity
equation with a sink term shows up naturally).

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


title: One shot profilometry using iterative two-step temporal phase-unwrapping

abstract:
  This paper reviews two techniques that have been recently published for 3D
profilometry and proposes one shot profilometry using iterative two-step
temporal phase-unwrapping by combining the composite fringe projection and the
iterative two-step temporal phase unwrapping algorithm. In temporal phase
unwrapping, many images with different frequency fringe pattern are needed to
project which would take much time. In order to solve this problem, Ochoa
proposed a phase unwrapping algorithm based on phase partitions using a
composite fringe, which only needs projecting one composite fringe pattern with
four kinds of frequency information to complete the process of 3D profilometry.
However, we found that the fringe order determined through the construction of
phase partitions tended to be imprecise. Recently, we proposed an iterative
two-step temporal phase unwrapping algorithm, which can achieve high
sensitivity and high precision shape measurement. But it needs multiple frames
of fringe images which would take much time. In order to take into account both
the speed and accuracy of 3D shape measurement, we get a new, and more accurate
unwrapping method based on composite fringe pattern by combining these two
techniques. This method not only retains the speed advantage of Ochoa's
algorithm, but also greatly improves its measurement accuracy. Finally, the
experimental evaluation is conducted to prove the validity of the proposed
method, and the experimental results show that this method is feasible.


title:
MobilitApp: Analysing mobility data of citizens in the metropolitan area
  of Barcelona

abstract:
  MobilitApp is a platform designed to provide smart mobility services in urban
areas. It is designed to help citizens and transport authorities alike.
Citizens will be able to access the MobilitApp mobile application and decide
their optimal transportation strategy by visualising their usual routes, their
carbon footprint, receiving tips, analytics and general mobility information,
such as traffic and incident alerts. Transport authorities and service
providers will be able to access information about the mobility pattern of
citizens to o er their best services, improve costs and planning. The
MobilitApp client runs on Android devices and records synchronously, while
running in the background, periodic location updates from its users. The
information obtained is processed and analysed to understand the mobility
patterns of our users in the city of Barcelona, Spain.


title: You never surf alone. Ubiquitous tracking of users' browsing habits

abstract:
  In the early age of the internet users enjoyed a large level of anonymity. At
the time web pages were just hypertext documents; almost no personalisation of
the user experience was o ered. The Web today has evolved as a world wide
distributed system following specific architectural paradigms. On the web now,
an enormous quantity of user generated data is shared and consumed by a network
of applications and services, reasoning upon users expressed preferences and
their social and physical connections. Advertising networks follow users'
browsing habits while they surf the web, continuously collecting their traces
and surfing patterns. We analyse how users tracking happens on the web by
measuring their online footprint and estimating how quickly advertising
networks are able to pro le users by their browsing habits.


title:
On Content-Based Recommendation and User Privacy in Social-Tagging
  Systems

abstract:
  Recommendation systems and content filtering approaches based on annotations
and ratings, essentially rely on users expressing their preferences and
interests through their actions, in order to provide personalised content. This
activity, in which users engage collectively, has been named social tagging.
Although it has opened a myriad of new possibilities for application
interoperability on the semantic web, it is also posing new privacy threats.
Social tagging consists in describing online or online resources by using
free-text labels (i.e. tags), therefore exposing the user's profile and
activity to privacy attacks. Tag forgery is a privacy enhancing technology
consisting of generating tags for categories or resources that do not reflect
the user's actual preferences. By modifying their profile, tag forgery may have
a negative impact on the quality of the recommendation system, thus protecting
user privacy to a certain extent but at the expenses of utility loss. The
impact of tag forgery on content-based recommendation is, therefore,
investigated in a real-world application scenario where different forgery
strategies are evaluated, and the consequent loss in utility is measured and
compared.


title:
Effective Passivant Pseudopotentials for semiconductors: beyond the
  spherical approximation

abstract:
  A new type of effective atomic pseudopotential for passivation of
semiconductor surfaces is presented. It is shown that the spherical
approximation used in the effective and empirical pseudopotential methods is
not suitable for describing passivants and that, instead, they have to be
regarded as complex quantities. Since the new seudopotentials cannot be handled
as usual bulk ones, the way of implementing them in atomistic methods is
described here, together with a methodology for extracting them trough an
analytic connection to density functional theory, meaning that the new type of
surface potential keeps the {\it ab inito} identity. The effectiveness and high
transferability of this new approach is demonstrated by generating passivant
potentials for six different semiconductor compounds (GaAs, AlAs, Si, Ge, CdSe
and ZnO) and testing them on different kinds of surfaces, including a
passivated 68 atoms CdSe quantum wire in wurtzite structure, obtaining always
an excellent agreement to density functional theory calculations done on the
same systems.


title:
High visibility time-energy entangled photons from a silicon
  nanophotonic chip

abstract:
  Advances in quantum photonics have shown that chip-scale quantum devices are
translating from the realm of basic research to applied technologies. Recent
developments in integrated photonic circuits and single photon detectors
indicate that the bottleneck for fidelity in quantum photonic processes will
ultimately lie with the photon sources. We present and demonstrate a silicon
nanophotonic chip capable of emitting telecommunication band photon pairs that
exhibit the highest raw degree of time-energy entanglement from a
micro/nanoscale source, to date. Biphotons are generated through
cavity-enhanced spontaneous four-wave mixing (SFWM) in a high-Q silicon
microdisk resonator, wherein the nature of the triply-resonant generation
process leads to a dramatic Purcell enhancement, resulting in highly efficient
pair creation rates as well as extreme suppression of the photon noise
background. The combination of the excellent photon source and a new phase
locking technique, allow for the observation of a nearly perfect coincidence
visibility of (96.6 $\pm$ 1.1)$\%$, without any background subtraction, at a
large pair generation rate of (4.40 $\pm$ 0.07) $\times$ 10$^5$ pairs/s.


title: Multimode optomechanical system in the quantum regime

abstract:
  We realise a simple and robust optomechanical system with a multitude of
long-lived ($Q>10^7$) mechanical modes in a phononic-bandgap shielded membrane
resonator. An optical mode of a compact Fabry-Perot resonator detects these
modes' motion with a measurement rate ($96~\mathrm{kHz}$) that exceeds the
mechanical decoherence rates already at moderate cryogenic temperatures
($10\,\mathrm{K}$). Reaching this quantum regime entails, i.~a., quantum
measurement backaction exceeding thermal forces, and thus detectable
optomechanical quantum correlations. In particular, we observe ponderomotive
squeezing of the output light mediated by a multitude of mechanical resonator
modes, with quantum noise suppression up to -2.4 dB (-3.6 dB if corrected for
detection losses) and bandwidths $\lesssim 90\,\mathrm{ kHz}$. The multi-mode
nature of the employed membrane and Fabry-Perot resonators lends itself to
hybrid entanglement schemes involving multiple electromagnetic, mechanical, and
spin degrees of freedom.


title:
Direct reconstruction of the two-dimensional pair distribution function
  in systems with angular correlations

abstract:
  An x-ray scattering approach to determine the two-dimensional (2D) pair
distribution function (PDF) in partially ordered 2D systems is proposed. We
derive relations between the structure factor and PDF that enable quantitative
studies of positional and bond-orientational (BO) order in real space. We apply
this approach in the x-ray study of a liquid crystal (LC) film undergoing the
smectic-hexatic phase transition, to analyze the interplay between the
positional and BO order during the temperature evolution of the LC film. We
analyze the positional correlation length in different directions in real
space.


title:
Dimensions of irreducible modules for partition algebras and tensor
  power multiplicities for symmetric and alternating groups

abstract:
  The partition algebra $\mathsf{P}_k(n)$ and the symmetric group
$\mathsf{S}_n$ are in Schur-Weyl duality on the $k$-fold tensor power
$\mathsf{M}_n^{\otimes k}$ of the permutation module $\mathsf{M}_n$ of
$\mathsf{S}_n$, so there is a surjection $\mathsf{P}_k(n) \to \mathsf{Z}_k(n)
:= \mathsf{End}_{\mathsf{S}_n}(\mathsf{M}_n^{\otimes k}),$ which is an
isomorphism when $n \ge 2k$. We prove a dimension formula for the irreducible
modules of the centralizer algebra $\mathsf{Z}_k(n)$ in terms of Stirling
numbers of the second kind. Via Schur-Weyl duality, these dimensions equal the
multiplicities of the irreducible $\mathsf{S}_n$-modules in
$\mathsf{M}_n^{\otimes k}$. Our dimension expressions hold for any $n \geq 1$
and $k\ge0$. Our methods are based on an analog of Frobenius reciprocity that
we show holds for the centralizer algebras of arbitrary finite groups and their
subgroups acting on a finite-dimensional module. This enables us to generalize
the above result to various analogs of the partition algebra including the
centralizer algebra for the alternating group acting on $\mathsf{M}_n^{\otimes
k}$ and the quasi-partition algebra corresponding to tensor powers of the
reflection representation of $\mathsf{S}_n$.


title: Inference by Reparameterization in Neural Population Codes

abstract:
  Behavioral experiments on humans and animals suggest that the brain performs
probabilistic inference to interpret its environment. Here we present a new
general-purpose, biologically-plausible neural implementation of approximate
inference. The neural network represents uncertainty using Probabilistic
Population Codes (PPCs), which are distributed neural representations that
naturally encode probability distributions, and support marginalization and
evidence integration in a biologically-plausible manner. By connecting multiple
PPCs together as a probabilistic graphical model, we represent multivariate
probability distributions. Approximate inference in graphical models can be
accomplished by message-passing algorithms that disseminate local information
throughout the graph. An attractive and often accurate example of such an
algorithm is Loopy Belief Propagation (LBP), which uses local marginalization
and evidence integration operations to perform approximate inference
efficiently even for complex models. Unfortunately, a subtle feature of LBP
renders it neurally implausible. However, LBP can be elegantly reformulated as
a sequence of Tree-based Reparameterizations (TRP) of the graphical model. We
re-express the TRP updates as a nonlinear dynamical system with both fast and
slow timescales, and show that this produces a neurally plausible solution. By
combining all of these ideas, we show that a network of PPCs can represent
multivariate probability distributions and implement the TRP updates to perform
probabilistic inference. Simulations with Gaussian graphical models demonstrate
that the neural network inference quality is comparable to the direct
evaluation of LBP and robust to noise, and thus provides a promising mechanism
for general probabilistic inference in the population codes of the brain.


title:
Modeling of Inelastic Collisions in a Multifluid Plasma: Ionization and
  Recombination

abstract:
  A model for ionization and recombination collisions in a multifluid plasma is
formulated using the framework introduced in previous work [{Phys. Plasmas}
\textbf{22}, 093512 (2015)]. The exchange source terms for density, momentum
and energy are detailed for the case of electron induced ionization and three
body recombination collisions with isotropic scattering. The principle of
detailed balance is enforced at the microscopic level. We describe how to
incorporate the standard collisional-radiative model into the multifluid
equations using the current formulation. Numerical solutions of the
collisional-radiative rate equations for atomic hydrogen are presented to
highlight the impact of the multifluid effect on the kinetics.


title: Dense PG(n-1,2)-free binary matroids

abstract:
  For each integer $n \geq 2$, we prove that, if $M$ is a simple rank-$r$
$PG(n-1,2)$-free binary matroid with $|M|>\left(1-\frac{3}{2^n}\right)2^r$,
then there is a triangle-free corank-$(n-2)$ flat of $M$.


title: Texture zeros in neutrino mass matrix

abstract:
  The Standard Model does not explain the hierarchy problem. Before the
discovery of nonzero lepton mixing angle {\theta}13 high hopes in explanation
of the shape of the lepton mixing matrix were combined with non abelian
symmetries. Nowadays, assuming one Higgs doublet, it is unlikely that this is
still valid. Texture zeroes, that are combined with abelian symmetries, are
intensively studied. The neutrino mass matrix is a natural way to study such
symmetries.


title: Isothermal and Adiabatic Elastic Tensors

abstract:
  The adiabatic elastic modulus is often useful in the high frequency response
of materials. Unfortunately, it can be much more difficult to directly measure
the adiabatic elastic modulus of material than the isothermal elastic modulus.
We derive the relationship between the adiabatic and isothermal elastic tensors
from the first law of thermodynamics.


title: A stochastic integral of operator-valued functions

abstract:
  In this note we define and study a Hilbert space-valued stochastic integral
of operator-valued functions with respect to Hilbert space-valued measures. We
show that this integral generalizes the classical Ito stochastic integral of
adapted processes with respect to normal martingales and the Ito integral in a
Fock space


title: The flavour problem and family symmetry beyond the Standard Model

abstract:
  In the frame of two Higgs doublet model we try to explain the lepton masses
and mixing matrix elements assuming that neutrinos are Dirac particles.
Discrete family symmetry groups, which are subgroups of U(3) up to the 1025
order are considered. Like in the one Higgs Standard Model, we found that
discrete family symmetries do not give satisfactory answer for this basic
questions in the flavour problem.


title:
Unraveling the Planar-Globular Transition in Gold Nanoclusters through
  Evolutionary Search

abstract:
  Au nanoclusters are of technological relevance for catalysis, photonics,
sensors, and of fundamental scientific interest owing to planar to globular
structural transformation at an anomalously high number of atoms i.e. in the
range 12-14. The nature and causes of this transition remain a mystery. In
order to unravel this conundrum, high throughput density functional theory
(DFT) calculations, coupled with a global structural optimization scheme based
on a modified genetic algorithm (GA) are conducted. More than 20,000 Au$_{12}$,
Au$_{13}$, and Au$_{14}$ nanoclusters are evaluated. With any DFT functional,
globular and planar structures coexist across the size range of interest. The
planar-globular transition is gradual at room temperature rather than a sharp
transition as previously believed. The effects of anionicity, $\textit{s-d}$
band hybridization and long range interactions on the dimensional transition
are quantified by using the structures adjacent to minima. Anionicity
marginally changes the relative stability of the clusters. The degree of
$\textit{s-d}$ hybridization is varied via changing the Hubbard U value which
corroborate that $\textit{s-d}$ hybridization alone does not stabilize planar
structures. van der Waals interactions, on the other hand, stabilize globular
structures. These results elucidate the balance between the different reasons
of the dimensional transition in gold nanoclusters.


title:
An Optimal Energy Estimator to Reduce Correlated Noise for the EXO-200
  Light Readout

abstract:
  The energy resolution of the EXO-200 detector is limited by electronics noise
in the measurement of the scintillation response. Here we present a new
technique to extract optimal scintillation energy measurements for signals
split across multiple channels in the presence of correlated noise. The
implementation of these techniques improves the energy resolution of the
detector at the neutrinoless double beta decay Q-value from $\left[1.9641\pm
0.0039\right]\%$ to $\left[1.5820\pm 0.0044\right]\%$.


title: How semiconductor nanoplatelets form

abstract:
  Colloidal nanoplatelets - quasi-two-dimensional sheets of semiconductor
exhibiting efficient, spectrally pure fluorescence - form when liquid-phase
syntheses of spherical quantum dots are modified. Despite intense interest in
their properties, the mechanism behind their anisotropic shape and precise
atomic-scale thickness remains unclear, and even counterintuitive when their
crystal structure is isotropic. One commonly accepted explanation is that
nanoclusters nucleate within molecular templates and then fuse. Here, we test
this mechanism for zincblende nanoplatelets and show that they form instead due
to an intrinsic instability in growth kinetics. We synthesize CdSe and
CdS1-xSex nanoplatelets in template- and solvent-free isotropic melts
containing only cadmium carboxylate and chalcogen, a finding incompatible with
previous explanations. Our model, based on theoretical results showing enhanced
growth on narrow surface facets, rationalizes nanoplatelet formation and
experimental dependencies on temperature, time, and carboxylate length. Such
understanding should lead to improved syntheses, controlled growth on surfaces,
and broader libraries of nanoplatelet materials.


title: Quantum Collapse of a Charged $n$-dimensional BTZ-like Domain Wall

abstract:
  We investigate both the classical and quantum gravitational collapse of a
charged, non-rotating $n$-dimensional BTZ black hole in AdS space. This is done
by first deriving the conserved mass of a "spherically" symmetric domain wall,
which is then taken as the classical Hamiltonian of the domain wall.
  In the classical picture, we show that, as far as the asymptotic observer is
concerned, the details of the collapse depend on the amount of charge present
in the domain wall. In the both the extremal and non-extremal cases, the
collapse takes an infinite amount of observer time to complete. However, in the
over-charged case, the collapse never actually occurs, instead one finds an
oscillatory solution which prevents the formation of a naked singularity. As
far as the infalling observer is concerned, the collapse is completed within a
finite amount of proper time. Thus, the gravitational collapse follows that of
the typical formation of a black hole via gravitational collapse.
  Quantum mechanically, in the absence of induced quasi-particle production and
fluctuations of the metric geometry, we take primary interest in the behavior
of the collapse near the horizon and near the classical singularity from the
point of view of both asymptotic and infalling observers. For the asymptotic
observer, we find that quantum effects near the horizon do not change the
classical conclusions. For the infalling observer, the most interesting quantum
mechanical effect are when the collapsing shell approaches the classical
singularity. Here, we find, that the quantum effects in this region display
non-local effects, which depend on the energy density of the domain wall.


title: Bot or Not? Deciphering Time Maps for Tweet Interarrivals

abstract:
  This exploratory study used the R Statistical Software to perform Monte Carlo
simulation of time maps, which characterize events based on the elapsed time
since the last event and the time that will transpire until the next event, and
compare them to time maps from real Twitter users. Time maps are used to
explore differences in the interarrival patterns of Tweets between human users,
humans who use scheduling services like TweetDeck and HootSuite, and non-human
(bot) users. The results indicate that there are differences between the tweet
interarrival patterns across these categories of users, and that time maps
could potentially be used to automate the detection of bot accounts on Twitter.
This could enhance social media intelligence capabilities, help bot developers
build more human-like Twitter bots to avoid detection, or both.


title:
A Quantum Enigma Machine: Experimentally Demonstrating Quantum Data
  Locking

abstract:
  Claude Shannon proved in 1949 that information-theoretic-secure encryption is
possible if the encryption key is used only once, is random, and is at least as
long as the message itself. Notwithstanding, when information is encoded in a
quantum system, the phenomenon of quantum data locking allows one to encrypt a
message with a shorter key and still provide information-theoretic security. We
present one of the first feasible experimental demonstrations of quantum data
locking for direct communication and propose a scheme for a quantum enigma
machine that encrypts 6 bits per photon (containing messages, new encryption
keys, and forward error correction bits) with less than 6 bits per photon of
encryption key while remaining information-theoretically secure.


title:
Evaluating Power System Vulnerability to False Data Injection Attacks
  via Scalable Optimization

abstract:
  Physical consequences to power systems of false data injection cyber-attacks
are considered. Prior work has shown that the worst-case consequences of such
an attack can be determined using a bi-level optimization problem, wherein an
attack is chosen to maximize the physical power flow on a target line
subsequent to re-dispatch. This problem can be solved as a mixed-integer linear
program, but it is difficult to scale to large systems due to numerical
challenges. Three new computationally efficient algorithms to solve this
problem are presented. These algorithms provide lower and upper bounds on the
system vulnerability measured as the maximum power flow subsequent to an
attack. Using these techniques, vulnerability assessments are conducted for
IEEE 118-bus system and Polish system with 2383 buses.


title: An Elliptic Free Boundary Arising From the Jump of Conductivity

abstract:
  In this paper we consider a quasilinear elliptic PDE, $\text{div} (A(x,u)
\nabla u) =0$, where the underlying physical problem gives rise to a jump for
the conductivity $A(x,u)$, across a level surface for $u$. Our analysis
concerns Lipschitz regularity for the solution $u$, and the regularity of the
level surfaces, where $A(x,u)$ has a jump and the solution $u$ does not
degenerate.
  In proving Lipschitz regularity of solutions, we introduce a new and
unexpected type of ACF-monotonicity formula with two different operators, that
might be of independent interest, and surely can be applied in other related
situations. The proof of the monotonicity formula is done through careful
computations, and (as a byproduct) a slight generalization to a specific type
of variable matrix-valued conductivity is presented.


title:
Comment on "Negative Differential Conductivity in an Interacting Quantum
  Gas."

abstract:
  Labouvie \etal (\prl {\bf 115}, 050601, (20015)) recently demonstrated
negative differential conductivity (NDC) in a multi-well Bose-Einstein
condensate. They stated "we demonstrate that NDC originates from a nonlinear,
atom number dependent tunneling coupling in combination with fast collisional
decoherence." We show theoretically how the essential feature of NDC, a
reduction in atomic current caused by an increase in chemical potential, is
present in unitary dynamics through the well-known mechanism of macroscopic
self-trapping (MST), and that the collisional decoherence merely serves as a
quantitative modification of this.


title: Functional Hashing for Compressing Neural Networks

abstract:
  As the complexity of deep neural networks (DNNs) trend to grow to absorb the
increasing sizes of data, memory and energy consumption has been receiving more
and more attentions for industrial applications, especially on mobile devices.
This paper presents a novel structure based on functional hashing to compress
DNNs, namely FunHashNN. For each entry in a deep net, FunHashNN uses multiple
low-cost hash functions to fetch values in the compression space, and then
employs a small reconstruction network to recover that entry. The
reconstruction network is plugged into the whole network and trained jointly.
FunHashNN includes the recently proposed HashedNets as a degenerated case, and
benefits from larger value capacity and less reconstruction loss. We further
discuss extensions with dual space hashing and multi-hops. On several benchmark
datasets, FunHashNN demonstrates high compression ratios with little loss on
prediction accuracy.