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1807.02725 | Numerical analysis of a discontinuous Galerkin method for
Cahn-Hilliard-Navier-Stokes equations | In this paper, we derive a theoretical analysis of an interior penalty
discontinuous Galerkin methods for solving the Cahn-Hilliard-Navier-Stokes
model problem. We prove unconditional unique solvability of the discrete
system, obtain unconditional discrete energy dissipation law, and derive
stability bounds with a generalized chemical energy density. Convergence of the
method is obtained by proving optimal a priori error estimates. Our analysis of
the unique solvability is valid for both symmetric and non-symmetric versions
of the discontinuous Galerkin formulation.
| math.NA |
1807.02726 | Variational Lagrangian formulation of the Euler equations for
incompressible flow: A simple derivation | In 1966, Arnold [1] showed that the Lagrangian flow of ideal incompressible
fluids (described by Euler equations) coincide with the geodesic flow on the
manifold of volume preserving diffeomorphisms of the fluid domain. Arnold's
proof and the subsequent work on this topic rely heavily on the properties of
Lie groups and Lie algebras which remain unfamiliar to most fluid dynamicists.
In this note, we provide a simple derivation of Arnold's result which only uses
the classical methods of calculus of variations. In particular, we show that
the Lagrangian flow maps generated by the solutions of the incompressible Euler
equations coincide with the stationary curves of an appropriate energy
functional when the extremization is carried out over the set of
volume-preserving diffeomorphisms.
| physics.flu-dyn math-ph math.MP physics.class-ph |
1807.02727 | Flavored Non-Minimal Left-Right Symmetric Model Fermion Masses and
Mixings | A complete study on the fermion masses and flavor mixing is presented in a
non-minimal left-right symmetric model (NMLRMS) where the ${\bf S}_{3}\otimes
{\bf Z}_{2}\otimes {\bf Z}^{e}_{2}$ flavor symmetry drives the Yukawa
couplings. In the quark sector, the mass matrices possess a kind of the
generalized Fritzsch textures that allow us to fit the CKM mixing matrix in
good agreement to the last experimental data. In the lepton sector, on the
other hand, a soft breaking of the $\mu\leftrightarrow \tau$ symmetry provides
a non zero and non maximal reactor and atmospheric angles, respectively. The
inverted and degenerate hierarchy are favored in the model where a set of free
parameters is found to be consistent with the current neutrino data.
| hep-ph |
1807.02728 | Abnormality Detection inside Blood Vessels with Mobile Nanomachines | Motivated by the numerous healthcare applications of molecular communication
within Internet of Bio-Nano Things (IoBNT), this work addresses the problem of
abnormality detection in a blood vessel using multiple biological embedded
computing devices called cooperative biological nanomachines (CNs), and a
common receiver called the fusion center (FC). Due to blood flow inside a
vessel, each CN and the FC are assumed to be mobile. In this work, each of the
CNs perform abnormality detection with certain probabilities of detection and
false alarm by counting the number of molecules received from a source, e.g.,
infected tissue. These CNs subsequently report their local decisions to a FC
over a diffusion-advection blood flow channel using different types of
molecules in the presence of inter-symbol interference, multi-source
interference, and counting errors. Due to limited computational capability at
the FC, OR and AND logic based fusion rules are employed to make the final
decision after obtaining each local decision based on the optimal likelihood
ratio test. For the aforementioned system, probabilities of detection and false
alarm at the FC are derived for OR and AND fusion rules. Finally, simulation
results are presented to validate the derived analytical results, which provide
important insights.
| cs.IT math.IT |
1807.02729 | Sur un syst\`eme int\'egrable \`a bord | [French] We develop new applications of Sklyanin's $K$-matrix formalism to
the study of periodic solutions of the sinh-Gordon equation.
| hep-th |
1807.02730 | Model-Independent Bounds on $R(J/\psi)$ | We present a model-independent bound on $R(J/\psi) \! \equiv \! \mathcal{BR}
(B_c^+ \rightarrow J/\psi \, \tau^+\nu_\tau)/ \mathcal{BR} (B_c^+ \rightarrow
J/\psi \, \mu^+\nu_\mu)$. This bound is constructed by constraining the form
factors through a combination of dispersive relations, heavy-quark relations at
zero-recoil, and the limited existing determinations from lattice QCD. The
resulting 95\% confidence-level bound, $0.20\leq R(J/\psi)\leq0.39$, agrees
with the recent LHCb result at $1.3 \, \sigma$, and rules out some previously
suggested model form factors.
| hep-ph hep-ex hep-lat nucl-th |
1807.02731 | Lorentzian Einstein-Ricci Flows | We study the Ricci flow for the Lorentzian Einstein-Hilbert action. We show
that Einstein gravity emerges as a fixed point of the Einstein-Ricci flow
equations and derive a renormalization group flow in Euclidean signature. By
considering linearizations near the fixed point, the dynamics of the metric
reveal that curvature deformations flow according to a forward heat equation
with the stress-energy tensor acting as a source.
| gr-qc hep-th math-ph math.MP |
1807.02732 | Simultaneously high electron and hole mobilities in cubic boron-V
compounds: BP, BAs and BSb | Through first-principles calculations, the phonon-limited transport
properties of cubic boron-V compounds (BP, BAs and BSb) are studied. We find
that the high optical phonon frequency in these compounds leads to the
substantial suppression of polar scattering and the reduction of inter-valley
transition mediated by large-wavevector optical phonons, both of which
significantly facilitate charge transport. We also discover that BAs
simultaneously has a high hole mobility (2110 cm2/V-s) and electron mobility
(1400 cm2/V-s) at room temperature, which is rare in semiconductors. Our
findings present a new insight in searching high mobility polar semiconductors,
and point to BAs as a promising material for electronic and photovoltaic
devices in addition to its predicted high thermal conductivity.
| cond-mat.mtrl-sci |
1807.02733 | Energy transfer from intense laser pulse to dielectrics in
time-dependent density functional theory | Energy transfer processes from a high-intensity ultrashort laser pulse to
electrons in simple dielectrics, silicon, diamond, and $\alpha$-quartz are
theoretically investigated by first-principles calculations based on
time-dependent density functional theory (TDDFT). Dependences on frequency as
well as intensity of the laser pulse are examined in detail, making a
comparison with the Keldysh theory. Although the Keldysh theory reliably
reproduces the main features of the TDDFT calculation, we find some deviations
between results by the two theories. The origin of the differences is examined
in detail.
| physics.optics |
1807.02734 | Homogeneous Real (2,3,5) Distributions with Isotropy | We classify multiply transitive homogeneous real (2,3,5) distributions up to
local diffeomorphism equivalence.
| math.DG |
1807.02735 | Coalgebraic Tools for Randomness-Conserving Protocols | We propose a coalgebraic model for constructing and reasoning about
state-based protocols that implement efficient reductions among random
processes. We provide basic tools that allow efficient protocols to be
constructed in a compositional way and analyzed in terms of the tradeoff
between state and loss of entropy. We show how to use these tools to construct
various entropy-conserving reductions between processes.
| cs.LO cs.FL cs.IT math.IT math.PR |
1807.02736 | Robust Learning of Trimmed Estimators via Manifold Sampling | We adapt a manifold sampling algorithm for the nonsmooth, nonconvex
formulations of learning that arise when imposing robustness to outliers
present in the training data. We demonstrate the approach on objectives based
on trimmed loss. Empirical results show that the method has favorable scaling
properties. Although savings in time come at the expense of not certifying
optimality, the algorithm consistently returns high-quality solutions on the
trimmed linear regression and multiclass classification problems tested.
| math.OC |
1807.02737 | A Causal Bootstrap | The bootstrap, introduced by Efron (1982), has become a very popular method
for estimating variances and constructing confidence intervals. A key insight
is that one can approximate the properties of estimators by using the empirical
distribution function of the sample as an approximation for the true
distribution function. This approach views the uncertainty in the estimator as
coming exclusively from sampling uncertainty. We argue that for causal
estimands the uncertainty arises entirely, or partially, from a different
source, corresponding to the stochastic nature of the treatment received. We
develop a bootstrap procedure that accounts for this uncertainty, and compare
its properties to that of the classical bootstrap.
| stat.ME |
1807.02738 | Homogeneous prime elements in normal two-dimensional graded rings | We prove necessary and sufficient conditions for the existence of homogeneous
prime elements in normal N-graded rings of dimension two, in terms of rational
coefficient Weil divisors on projective curves.
| math.AC |
1807.02739 | Detecting Synapse Location and Connectivity by Signed Proximity
Estimation and Pruning with Deep Nets | Synaptic connectivity detection is a critical task for neural reconstruction
from Electron Microscopy (EM) data. Most of the existing algorithms for synapse
detection do not identify the cleft location and direction of connectivity
simultaneously. The few methods that computes direction along with contact
location have only been demonstrated to work on either dyadic (most common in
vertebrate brain) or polyadic (found in fruit fly brain) synapses, but not on
both types. In this paper, we present an algorithm to automatically predict the
location as well as the direction of both dyadic and polyadic synapses. The
proposed algorithm first generates candidate synaptic connections from
voxelwise predictions of signed proximity generated by a 3D U-net. A second 3D
CNN then prunes the set of candidates to produce the final detection of cleft
and connectivity orientation. Experimental results demonstrate that the
proposed method outperforms the existing methods for determining synapses in
both rodent and fruit fly brain.
| cs.CV |
1807.02740 | Data-driven Upsampling of Point Clouds | High quality upsampling of sparse 3D point clouds is critically useful for a
wide range of geometric operations such as reconstruction, rendering, meshing,
and analysis. In this paper, we propose a data-driven algorithm that enables an
upsampling of 3D point clouds without the need for hard-coded rules. Our
approach uses a deep network with Chamfer distance as the loss function,
capable of learning the latent features in point clouds belonging to different
object categories. We evaluate our algorithm across different amplification
factors, with upsampling learned and performed on objects belonging to the same
category as well as different categories. We also explore the desirable
characteristics of input point clouds as a function of the distribution of the
point samples. Finally, we demonstrate the performance of our algorithm in
single-category training versus multi-category training scenarios. The final
proposed model is compared against a baseline, optimization-based upsampling
method. Results indicate that our algorithm is capable of generating more
uniform and accurate upsamplings.
| cs.CV cs.CG cs.LG |
1807.02741 | Algebraic signatures of convex and non-convex codes | A convex code is a binary code generated by the pattern of intersections of a
collection of open convex sets in some Euclidean space. Convex codes are
relevant to neuroscience as they arise from the activity of neurons that have
convex receptive fields. In this paper, we use algebraic methods to determine
if a code is convex. Specifically, we use the neural ideal of a code, which is
a generalization of the Stanley-Reisner ideal. Using the neural ideal together
with its standard generating set, the canonical form, we provide algebraic
signatures of certain families of codes that are non-convex. We connect these
signatures to the precise conditions on the arrangement of sets that prevent
the codes from being convex. Finally, we also provide algebraic signatures for
some families of codes that are convex, including the class of
intersection-complete codes. These results allow us to detect convexity and
non-convexity in a variety of situations, and point to some interesting open
questions.
| q-bio.NC cs.DM math.CO |
1807.02742 | On automorphisms of algebraic curves | An irreducible, algebraic curve $\mathcal X_g$ of genus $g\geq 2$ defined
over an algebraically closed field $k$ of characteristic $\mbox{char } \, k = p
\geq 0$, has finite automorphism group $\mbox{Aut} (\mathcal X_g)$. In this
paper we describe methods of determining the list of groups $\mbox{Aut}
(\mathcal X_g)$ for a fixed $g\geq 2$. Moreover, equations of the corresponding
families of curves are given when possible.
| math.AG |
1807.02743 | Outflows in the Seyfert 2 galaxy NGC5643 traced by the [SIII] emission | We use Gemini Multi-Object Spectrograph (GMOS) Integral Field Unit (IFU)
observations of the inner 285$\times$400 pc$^2$ region of the Seyfert 2 galaxy
NGC 5643 to map the [SIII]$\lambda9069$ emission-line flux distribution and
kinematics, as well as the stellar kinematics, derived by fitting the
CaII$\lambda\lambda\lambda$8498,8542,8662 triplet, at a spatial resolution of
45 pc. The stellar velocity field shows regular rotation, with a projected
velocity of 100 km/s and kinematic major axis along Position Angle
$PA=-36^\circ$. A ring of low stellar velocity dispersion values ($\sim$70
km/s), attributed to young/intermediate age stellar populations, is seen
surrounding the nucleus with radius of 50 pc. We found that the [SIII] flux
distribution shows an elongated structure along the east-west direction and its
kinematics is dominated by outflows within a bi-cone at an ionized gas outflow
rate of 0.3 M$_\odot$ yr$^{-1}$. In addition, velocity slices across the
[SIII]$\lambda9069$ emission-line reveal a kinematic component attributed to
rotation of gas in the plane of the galaxy.
| astro-ph.GA |
1807.02744 | On Eisenstein polynomials and zeta polynomials | Eisenstein polynomials, which were defined by Oura, are analogues of the
concept of an Eisenstein series. Oura conjectured that there exist some
analogous properties between Eisenstein series and Eisenstein polynomials. In
this paper, we provide new analogous properties of Eisenstein polynomials and
zeta polynomials. These properties are finite analogies of certain properties
of Eisenstein series.
| math.CO math.NT |
1807.02745 | A Deep Generative Model of Vowel Formant Typology | What makes some types of languages more probable than others? For instance,
we know that almost all spoken languages contain the vowel phoneme /i/; why
should that be? The field of linguistic typology seeks to answer these
questions and, thereby, divine the mechanisms that underlie human language. In
our work, we tackle the problem of vowel system typology, i.e., we propose a
generative probability model of which vowels a language contains. In contrast
to previous work, we work directly with the acoustic information -- the first
two formant values -- rather than modeling discrete sets of phonemic symbols
(IPA). We develop a novel generative probability model and report results based
on a corpus of 233 languages.
| cs.CL |
1807.02746 | Prompt neutrinos and intrinsic charm at SHiP | We present a new evaluation of the far-forward neutrino plus antineutrino
flux and number of events from charm hadron decays in a 400 GeV proton beam
dump experiment like the Search for Hidden Particles (SHiP). Using
next-to-leading order perturbative QCD and a model for intrinsic charm, we
include intrinsic transverse momentum effects and other kinematic angular
corrections. We compare this flux to a far-forward flux evaluated with
next-to-leading order perturbative QCD, without intrinsic transverse momentum,
that used the angular distribution of charm quarks rather than the neutrinos
from their decays. The tau neutrino plus antineutrino number of events in the
perturbative QCD evaluation is reduced by a factor of about three when
intrinsic transverse momentum and the full decay kinematics are included. We
show that intrinsic charm contributions can significantly enhance the number of
events from neutrinos from charm hadron decays. Measurements of the number of
events from tau neutrino plus antineutrino interactions and of the muon charge
asymmetry as a function of energy can be used to constrain intrinsic charm
models.
| hep-ph |
1807.02747 | On the Complexity and Typology of Inflectional Morphological Systems | We quantify the linguistic complexity of different languages' morphological
systems. We verify that there is an empirical trade-off between paradigm size
and irregularity: a language's inflectional paradigms may be either large in
size or highly irregular, but never both. Our methodology measures paradigm
irregularity as the entropy of the surface realization of a paradigm -- how
hard it is to jointly predict all the surface forms of a paradigm. We estimate
this by a variational approximation. Our measurements are taken on large
morphological paradigms from 31 typologically diverse languages.
| cs.CL |
1807.02748 | Latent Semantic Analysis Approach for Document Summarization Based on
Word Embeddings | Since the amount of information on the internet is growing rapidly, it is not
easy for a user to find relevant information for his/her query. To tackle this
issue, much attention has been paid to Automatic Document Summarization. The
key point in any successful document summarizer is a good document
representation. The traditional approaches based on word overlapping mostly
fail to produce that kind of representation. Word embedding, distributed
representation of words, has shown an excellent performance that allows words
to match on semantic level. Naively concatenating word embeddings makes the
common word dominant which in turn diminish the representation quality. In this
paper, we employ word embeddings to improve the weighting schemes for
calculating the input matrix of Latent Semantic Analysis method. Two
embedding-based weighting schemes are proposed and then combined to calculate
the values of this matrix. The new weighting schemes are modified versions of
the augment weight and the entropy frequency. The new schemes combine the
strength of the traditional weighting schemes and word embedding. The proposed
approach is experimentally evaluated on three well-known English datasets, DUC
2002, DUC 2004 and Multilingual 2015 Single-document Summarization for English.
The proposed model performs comprehensively better compared to the
state-of-the-art methods, by at least 1% ROUGE points, leading to a conclusion
that it provides a better document representation and a better document summary
as a result.
| cs.CL |
1807.02749 | A comprehensive model of the meteoroid environment around Mercury | To characterize the meteoroid environment around Mercury and its contribution
to the planet's exosphere, we combined four distinctive sources of meteoroids
in the solar system: main-belt asteroids, Jupiter family comets, Halley-type
comets, and Oort Cloud comets. All meteoroid populations are described by
currently available dynamical models. We used a recent calibration of the
meteoroid influx onto Earth as a constraint for the combined population model
on Mercury. We predict vastly different distributions of orbital elements,
impact velocities and directions of arrival for all four meteoroid populations
at Mercury. We demonstrate that the most likely model of Mercury's meteoroid
environment- in the sense of agreement with Earth -provides good agreement with
previously reported observations of Mercury's exosphere by the MESSENGER
spacecraft and is not highly sensitive to variations of uncertain parameters
such as the ratio of these populations at Earth, the size frequency
distribution, and the collisional lifetime of meteoroids. Finally, we provide a
fully calibrated model consisting of high-resolution maps of mass influx and
surface vaporization rates for different values of Mercury's true anomaly
angle.
| astro-ph.EP |
1807.02750 | Hybrid quantum system with nitrogen-vacancy centers in diamond coupled
to surface phonon polaritons in piezomagnetic superlattices | We investigate a hybrid quantum system where an ensemble of nitrogen-vacancy
(NV) centers in diamond is interfaced with a piezomagnetic superlattice that
supports surface phonon polaritons (SPhPs). We show that the strong magnetic
coupling between the collective spin waves in the NV spin ensemble and the
quantized SPhPs can be realized, thanks to the subwavelength nature of the
SPhPs and relatively long spin coherence times. The magnon-polariton coupling
allows different modes of the SPhPs to be mapped and orthogonally stored in
different spatial modes of excitation in the solid medium. Because of its easy
implementation and high tunability, the proposed hybrid structure with NV spins
and piezoactive superlattices could be used for quantum memory and quantum
computation.
| quant-ph cond-mat.mes-hall |
1807.02751 | Role of contact work function, back surface field and conduction band
offset in CZTS solar cell | We employ simulation based approach for enhancing the efficiency of Cu2ZnSnS4
(CZTS) based solar cells. Initial benchmarking of simulation with the
experimentally reported solar cell in literature is performed by incorporating
a suitable defect model. We then explore the effects of: (a) conduction band
offset (CBO) at CZTS/CdS junction, (b) back surface field (BSF) due to an
additional layer with higher carrier density, and (c) high work function back
contact. Efficiency is observed to improve by about 70% upon optimizing the
above three parameters. We also observe that utilizing BSF in the configuration
can reduce the high work function requirement of the back contact. A work
function of 5.2 eV (e.g., using Ni), a BSF layer (e.g., using SnS), and a CBO
of 0.1 eV (e.g., using ZnS) constitute an optimal configuration.
| physics.app-ph cond-mat.mtrl-sci |
1807.02752 | Real-time stereo vision-based lane detection system | The detection of multiple curved lane markings on a non-flat road surface is
still a challenging task for automotive applications. To make an improvement,
the depth information can be used to greatly enhance the robustness of the lane
detection systems. The proposed system in this paper is developed from our
previous work where the dense vanishing point Vp is estimated globally to
assist the detection of multiple curved lane markings. However, the outliers in
the optimal solution may severely affect the accuracy of the least squares
fitting when estimating Vp. Therefore, in this paper we use Random Sample
Consensus to update the inliers and outliers iteratively until the fraction of
the number of inliers versus the total number exceeds our pre-set threshold.
This significantly helps the system to overcome some suddenly changing
conditions. Furthermore, we propose a novel lane position validation approach
which provides a piecewise weight based on Vp and the gradient to reduce the
gradient magnitude of the non-lane candidates. Then, we compute the energy of
each possible solution and select all satisfying lane positions for
visualisation. The proposed system is implemented on a heterogeneous system
which consists of an Intel Core i7-4720HQ CPU and a NVIDIA GTX 970M GPU. A
processing speed of 143 fps has been achieved, which is over 38 times faster
than our previous work. Also, in order to evaluate the detection precision, we
tested 2495 frames with 5361 lanes from the KITTI database (1637 lanes more
than our previous experiment). It is shown that the overall successful
detection rate is improved from 98.7% to 99.5%.
| cs.CV |
1807.02753 | Beurling-Fourier algebras of compact quantum groups: characters and
finite dimensional representations | In this paper we study weighted versions of Fourier algebras of compact
quantum groups. We focus on the spectral aspects of these Banach algebras in
two different ways. We first investigate their Gelfand spectrum, which shows a
connection to the maximal classical closed subgroup and its complexification.
Secondly, we study specific finite dimensional representations coming from the
complexification of the underlying quantum group. We demonstrate that the
weighted Fourier algebras can detect the complexification structure in the
special case of $SU_q(2)$, whose complexification is the quantum Lorentz group
$SL_q(2,\mathbb{C})$.
| math.OA math.FA |
1807.02754 | Model-Free Optimization Using Eagle Perching Optimizer | The paper proposes a novel nature-inspired technique of optimization. It
mimics the perching nature of eagles and uses mathematical formulations to
introduce a new addition to metaheuristic algorithms. The nature of the
proposed algorithm is based on exploration and exploitation. The proposed
algorithm is developed into two versions with some modifications. In the first
phase, it undergoes a rigorous analysis to find out their performance. In the
second phase it is benchmarked using ten functions of two categories; uni-modal
functions and multi-modal functions. In the third phase, we conducted a
detailed analysis of the algorithm by exploiting its controlling units or
variables. In the fourth and last phase, we consider real world optimization
problems with constraints. Both versions of the algorithm show an appreciable
performance, but analysis puts more weight to the modified version. The
competitive analysis shows that the proposed algorithm outperforms the other
tested metaheuristic algorithms. The proposed method has better robustness and
computational efficiency.
| cs.NE |
1807.02755 | An ALE meta-analytic comparison of verbal working memory tasks | Background: The n-back and Paced Auditory Serial Addition Test (PASAT) are
commonly used verbal working memory tasks that have partially overlapping uses
in clinical and experimental psychology. We performed three activation
likelihood estimation (ALE) meta-analyses, comparing two load levels of the
n-back task (2-back, 3-back) to the PASAT and to each-other. These analyses
aimed to determine the involvement of cognitive and emotional brain regions for
these tasks. Results: We observed higher overall likelihood of activation the
frontal eye fields in the 3-back. The PASAT exhibited higher overall activation
in the bilateral supplementary motor areas (SMA), left supramarginal gyrus, and
left superior parietal lobule. Furthermore, the 3-back exhibited higher
activation in the right SMA, and anterior mid-cingulate cortex versus the
2-back, and the PASAT exhibited higher activation in a cluster near the right
premotor area versus the 2-back. A laterality effect was observed in the
dorsolateral prefrontal cortex between the PASAT (left) and 3-back(right).
These data suggest greater activation of regions traditionally associated with
the phonological loop during the PASAT, compared to the 2- and 3-back tasks.
Furthermore, individual ALE analyses suggest involvement of emotional
processing and salience network regions (insula, cingulate) in addition to the
well-established verbal working memory regions (Broca's region, bilateral SMA,
premotor, posterior parietal cortices) in all 3 tasks. Conclusions: Here we
identify regions activated by the PASAT, which has not been meta-analytically
reviewed prior to this study. Using ALE meta-analysis, we have also identified
meaningful differences in activation associated with specific cognitive and
emotional aspects of verbal working memory during these tasks.
| q-bio.NC |
1807.02756 | Asymptotic behavior of spectral of Neumann-Poincare operator in Helmhotz
system | In this paper, we are concerned with the asymptotic behavior of the
Neumann-Poincare operator for Helmholtz system. By analyzing the asymptotic
behavior of spherical Bessel function near the origin and/or approach higher
order, we prove the asymptotic behavior of spectral of Neumann-Poincare
operator when frequency is small enough and/or the order is large enough. The
results show that spectral of Neumann-Poincare operator is continuous at the
origin and converges to zero from the complex plane in general.
| math.AP |
1807.02757 | Fringe pattern analysis using deep learning | In many optical metrology techniques, fringe pattern analysis is the central
algorithm for recovering the underlying phase distribution from the recorded
fringe patterns. Despite extensive research efforts for decades, how to extract
the desired phase information, with the highest possible accuracy, from the
minimum number of fringe patterns remains one of the most challenging open
problems. Inspired by recent successes of deep learning techniques for computer
vision and other applications, here, we demonstrate for the first time, to our
knowledge, that the deep neural networks can be trained to perform fringe
analysis, which substantially enhances the accuracy of phase demodulation from
a single fringe pattern. The effectiveness of the proposed method is
experimentally verified using carrier fringe patterns under the scenario of
fringe projection profilometry. Experimental results demonstrate its superior
performance in terms of high accuracy and edge-preserving over two
representative single-frame techniques: Fourier transform profilometry and
Windowed Fourier profilometry.
| eess.IV |
1807.02758 | Image Super-Resolution Using Very Deep Residual Channel Attention
Networks | Convolutional neural network (CNN) depth is of crucial importance for image
super-resolution (SR). However, we observe that deeper networks for image SR
are more difficult to train. The low-resolution inputs and features contain
abundant low-frequency information, which is treated equally across channels,
hence hindering the representational ability of CNNs. To solve these problems,
we propose the very deep residual channel attention networks (RCAN).
Specifically, we propose a residual in residual (RIR) structure to form very
deep network, which consists of several residual groups with long skip
connections. Each residual group contains some residual blocks with short skip
connections. Meanwhile, RIR allows abundant low-frequency information to be
bypassed through multiple skip connections, making the main network focus on
learning high-frequency information. Furthermore, we propose a channel
attention mechanism to adaptively rescale channel-wise features by considering
interdependencies among channels. Extensive experiments show that our RCAN
achieves better accuracy and visual improvements against state-of-the-art
methods.
| cs.CV |
1807.02759 | The role of angle dependent phase rotations of reaction amplitudes in
$\eta$ photoproduction on protons | It has recently been proven that the invariance of observables with respect
to angle dependent phase rotations of reaction amplitudes mixes multipoles
changing also their relative strength [1]. All contemporary partial wave
analyses (PWA) in $\eta$ photoproduction on protons, either energy dependent
(ED) [2-5] or single energy (SE) [6] do not take this effect into
consideration. It is commonly accepted that there exist quite some similarity
in the $E0+$ multipole for all PWA, but notable differences in this, but also
in remaining partial waves still remain. In this paper we demonstrate that once
this phase rotations are properly taken into account, all contemporary ED and
SE partial wave analysis become almost identical for the dominant $E0+$
multipole, and the agreement among all other multipoles becomes much better. We
also show that the the measured observables are almost equally well reproduced
for all PWA, and the remaining differences among multipoles can be attributed
solely to the difference of predictions for unmeasured observables. So, new
measurements are needed.
| nucl-th nucl-ex |
1807.02760 | Deterministic positioning of colloidal quantum dots on silicon nitride
nanobeam cavities | Engineering an array of precisely located cavity-coupled active media poses a
major experimental challenge in the field of hybrid integrated photonics. We
deterministically position solution processed colloidal quantum dots (QDs) on
high quality-factor silicon nitride nanobeam cavities and demonstrate
light-matter coupling. By lithographically defining a window on top of an
encapsulated cavity that is cladded in a polymer resist, and spin coating QD
solution, we can precisely control the placement of the QDs, which subsequently
couple to the cavity. We show that the number of QDs coupled to the cavity can
be controlled by the size of the window. Furthermore, we demonstrate Purcell
enhancement and saturable photoluminescence in this QD-cavity platform.
Finally, we deterministically position QDs on a photonic molecule and observe
QD-coupled cavity super-modes. Our results pave the way for controlling the
number of QDs coupled to a cavity by engineering the window size, and the QD
dimension, and will allow advanced studies in cavity enhanced single photon
emission, ultralow power nonlinear optics, and quantum many-body simulations
with interacting photons.
| physics.optics quant-ph |
1807.02761 | Topological Characterization of Rigid-Nonrigid Transition across the
Frenkel Line | The dynamics of supercritical fluids, a state of matter beyond the gas-liquid
critical point, changes from diffusive to oscillatory motions at high pressure.
This transition is believed to occur across a locus of thermodynamic states
called the Frenkel line. The Frenkel line has been extensively investigated
from the viewpoint of the dynamics, but its structural meaning is not still
well understood. This letter interprets the mesoscopic picture of the Frenkel
line entirely based on a topological and geometrical framework. This discovery
makes it possible to understand the mechanism of rigid/non-rigid transition
based not on the dynamics of individual atoms, but on their instantaneous
configurations. The topological classification method reveals that the
percolation of solid-like structures occurs above the rigid-nonrigid crossover
densities.
| cond-mat.stat-mech |
1807.02762 | Arbitrarily large violations of non-contextuality in single mode photon
states with positive Wigner function | Banaszek, W\'odkiewicz and others
(\cite{Banaszek},\cite{Chen},\cite{Chen-Zhang}) made the surprising discovery
that Einstein-Bell locality inequalities can be violated by the two mode
squeezed vacuum by a factor $\sqrt{2}$, in spite of the fact that the state has
a positive Wigner function. I use here the more general Gleason-Kochen-Specker
assumption of non-contextuality \cite{Gleason} to express classicality. I then
derive non-contextuality Bell inequalities for correlations of $N$ pseudo spins
embedded in an infinite dimensional continuous variable Hilbert space, and show
that their maximum possible quantum violation is by a factor $2^{(N-1)/2}$. I
find quantum states for which this maximum violation is reached. I also show
that the familiar displaced squeezed vacuum for a single optical mode, which
has a positive Wigner function, can violate the inequality by a factor $0.842
(\sqrt{2})^{N-1} $ for odd $N \geq 3$ . The arbitrarily large non-classicality
means that realizations of the pseudo-spin measurements even in a single mode
photon state might afford similar opportunities in quantum information tasks as
entangled $N$ qubit systems with large $N$.
| quant-ph |
1807.02763 | Inference of Population History using Coalescent HMMs: Review and
Outlook | Studying how diverse human populations are related is of historical and
anthropological interest, in addition to providing a realistic null model for
testing for signatures of natural selection or disease associations.
Furthermore, understanding the demographic histories of other species is
playing an increasingly important role in conservation genetics. A number of
statistical methods have been developed to infer population demographic
histories using whole-genome sequence data, with recent advances focusing on
allowing for more flexible modeling choices, scaling to larger data sets, and
increasing statistical power. Here we review coalescent hidden Markov models, a
powerful class of population genetic inference methods that can effectively
utilize linkage disequilibrium information. We highlight recent advances, give
advice for practitioners, point out potential pitfalls, and present possible
future research directions.
| q-bio.PE |
1807.02764 | Privacy-aware Distributed Hypothesis Testing | A distributed binary hypothesis testing (HT) problem involving two parties, a
remote observer and a detector, is studied. The remote observer has access to a
discrete memoryless source, and communicates its observations to the detector
via a rate-limited noiseless channel. The detector observes another discrete
memoryless source, and performs a binary hypothesis test on the joint
distribution of its own observations with those of the observer. While the goal
of the observer is to maximize the type II error exponent of the test for a
given type I error probability constraint, it also wants to keep a private part
of its observations as oblivious to the detector as possible. Considering both
equivocation and average distortion under a causal disclosure assumption as
possible measures of privacy, the trade-off between the communication rate from
the observer to the detector, the type II error exponent, and privacy is
studied. For the general HT problem, we establish single-letter inner bounds on
both the rate-error exponent-equivocation and rate-error exponent-distortion
trade-offs. Subsequently, single-letter characterizations for both trade-offs
are obtained (i) for testing against conditional independence of the observer's
observations from those of the detector, given some additional side-information
at the detector; and (ii) when the communication rate constraint over the
channel is zero. Finally, we show by providing a counterexample that, the
strong converse which holds for distributed HT without a privacy constraint,
does not hold when a privacy constraint is imposed. This implies that, in
general, the rate-error exponent-equivocation and rate-error
exponent-distortion trade-offs are not independent of the type I error
probability constraint.
| cs.IT math.IT |
1807.02765 | Conditional limit measure of one-dimensional quantum walk with absorbing
sink | We consider a two-state quantum walk on a line where after the first step an
absorbing sink is placed at the origin. The probability of finding the walker
at position $j$, conditioned on that it has not returned to the origin, is
investigated in the asymptotic limit. We prove a limit theorem for the
conditional probability distribution and show that it is given by the Konno's
density function modified by a pre-factor ensuring that the distribution
vanishes at the origin. In addition, we discuss the relation to the problem of
recurrence of a quantum walk and determine the Polya number. Our approach is
based on path counting and stationary phase approximation.
| quant-ph |
1807.02766 | The components of the singular locus of a component of a Springer fiber
over x^2 = 0 | For $x\in End(K^n)$ satisfying $x^2 = 0$ let $F_x$ be the variety of full
flags stable under the action of $x$ (Springer fiber over $x$). The full
classification of the components of $F_x$ according to their smoothness was
provided in a paper of Fresse-Melnikov in terms of both Young tableaux and link
patterns. Moreover in a paper of Fresse the purely combinatorial algorithm to
compute the singular locus of a singular components of $F_x$ is provided.
However this algorithm involves the computation of the graph of the component,
and the complexity of computations grows very quickly, so that in practice it
is impossible to use it. In this paper, we construct another algorithm, derived
from the algorithm of Fresse, providing all the components of the singular
locus of a singular component of $F_x$ in terms of link patterns constructed
straightforwardly from its link pattern.
| math.CO |
1807.02767 | Bounded linear operators in PN-spaces | In this paper, first we present a new useful way of formulating probabilistic
normed spaces. Then by using this formulation and probabilistic normed space
version of the Baire category theorem, we prove four important results of
functional analysis, i.e. the open mapping, closed graph, principle of uniform
boundedness and Banach-Steinhaus theorem in PN-spaces.
| math.FA |
1807.02768 | Quasilinear convexity and quasilinear stars in the ray space of a
supertropical quadratic form | Relying on rays, we search for submodules of a module V over a supertropical
semiring on which a given anisotropic quadratic form is quasilinear. Rays are
classes of a certain equivalence relation on V, that carry a notion of
convexity, which is consistent with quasilinearity. A criterion for
quasilinearity is specified by a Cauchy-Schwartz ratio which paves the way to a
convex geometry on Ray(V), supported by a "supertropical trigonometry".
Employing a (partial) quasiordering on Ray(V), this approach allows for
producing convex quasilinear sets of rays, as well as paths, containing a given
quasilinear set in a systematic way. Minimal paths are endowed with a
surprisingly rich combinatorial structure, delivered to the graph determined by
pairs of quasilinear rays -- apparently a fundamental object in the theory of
supertropical quadratic forms.
| math.RA |
1807.02769 | Degenerate Hamiltonian operator in higher-order canonical gravity -- the
problem and a remedy | Different routes towards the canonical formulation of a classical theory
result in different canonically equivalent Hamiltonians, while their quantum
counterparts are related through appropriate unitary transformation. However,
for higher-order theory of gravity, although two Hamiltonians emerging from the
same action differing by total derivative terms are related through canonical
transformation, the difference transpires while attempting canonical
quantization, which is predominant in non-minimally coupled higher-order theory
of gravity. We follow Dirac's constraint analysis to formulate phase-space
structures, in the presence (case-I) and absence (case-II) of total derivative
terms. While the coupling parameter plays no significant role as such for
case-I, quantization depends on its form explicitly in case-II, and as a
result, unitary transformation relating the two is not unique. We find certain
mathematical inconsistency in case-I, for modified Gauss-Bonnet-Dilatonic
coupled action, in particular. Thus, we conclude that total derivative terms
indeed play a major role in the quantum domain and should be taken care of
a-priori, for consistency.
| gr-qc hep-th |
1807.02770 | Universal entire functions that define order isomorphisms of countable
real sets | In 1895, Cantor showed that between every two countable dense real sets,
there is an order isomorphism. In fact, there is always such an order
isomorphism, which is the restriction of a universal entire function.
| math.CV |
1807.02771 | Ribosome self-assembly leads to overlapping reproduction cycles and
increases growth rate | In permissive environments, E. coli can double its dry mass every 21 minutes.
During this time, ribosomes, RNA polymerases, and the proteome are all doubled.
Yet, the question of how to relate bacterial doubling time to other
biologically relevant time scales in the growth process remains illusive, due
to the complex temporal nesting pattern of these processes. In particular, the
relation between the cell's doubling time and the ribosome assembly time is not
known. Here we develop a model that connects growth rate to ribosome assembly
time and show that the existence of a self-assembly step increases the overall
growth rate, because during ribosome self-assembly existing ribosomes can start
a new round of reproduction, by making a new batch of ribosomal proteins prior
to the completion of the previous round. This overlapping of ribosome
reproduction cycles increases growth rate beyond the serial-limit that is
typically assumed to hold. Using recent data from ribosome profiling and well
known measurements of the average translation rate, rigid bounds on the in-vivo
ribosome self-assembly time are set, which are robust to the assumptions
regarding the biological noises involved. At 21 minutes doubling time, the
ribosome assembly time is found to be approximately 6 minutes --- three fold
larger than the common estimate. We further use our model to explain the
detrimental effect of a recently discovered ribosome assembly inhibitor drug,
and predict the effect of limiting the expression of ribosome assembly
chaperons on the overall growth rate.
| q-bio.SC |
1807.02772 | Blow-up of solutions to critical semilinear wave equations with variable
coefficients | We verify the critical case $p=p_0(n)$ of Strauss' conjecture (1981)
concerning the blow-up of solutions to semilinear wave equations with variable
coefficients in $\mathbf{R}^n$, where $n\geq 2$. The perturbations of Laplace
operator are assumed to be smooth and decay exponentially fast at infinity. We
also obtain a sharp lifespan upper bound for solutions with compactly supported
data when $p=p_0(n)$. The unified approach to blow-up problems in all
dimensions combines several classical ideas in order to generalize and simplify
the method of Zhou(2007) and Zhou and Han (2014): exponential "eigenfunctions"
of the Laplacian are used to construct the test function $\phi_q$ for linear
wave equation with variable coefficients and John's method of iterations (1979)
is augmented with the "slicing method" of Agemi, Kurokawa and Takamura (2000)
for lower bounds in the critical case.
| math.AP |
1807.02773 | Online exploration outside a convex obstacle | A watchman path is a path such that a direct line of sight exists between
each point in some region and some point along the path. Here, we study the
online watchman path problem outside a convex polygon, i.e., in
$\mathbb{R}^2\setminus \Omega$, where $\Omega$ is a convex polygon that is not
known in advance. We present an algorithm for the exploration of the region
outside the polygon. We prove that the presented algorithms guarantees a
$\approx 22.77$ competitive ratio compared to the optimal offline watchman
path.
| cs.CG |
1807.02774 | Evolution and spatial distribution of Brillouin backscattering
associated to hybrid acoustic modes in sub-wavelength silica microfibers | The spectral evolution and spatial distribution of backscattered Brillouin
signals is experimentally investigated in sub-wavelength silica microfibers.
The Brillouin spectrum evolution reveals the different dynamics of the various
peaks, offering evidence of backscattering signals induced by acoustic waves
with phase velocity greater than that of the longitudinal wave. The spatial
distribution is found to have significant influence on the response of
Brillouin scattering under tensile load, with hybrid acoustic modes providing a
smaller response under axial strain. This insight into interactions between
optical and hybrid acoustic modes at sub-wavelength confinements could help
understand ultrasonic waves in tapered waveguides, and have potential
applications in optical sensing and detection.
| physics.optics |
1807.02775 | RBF-LOI: Augmenting Radial Basis Functions (RBFs) with Least Orthogonal
Interpolation (LOI) for Solving PDEs on Surfaces | We present a new method for the solution of PDEs on manifolds $\mathbb{M}
\subset \mathbb{R}^d$ of co-dimension one using stable scale-free radial basis
function (RBF) interpolation. Our method involves augmenting polyharmonic
spline (PHS) RBFs with polynomials to generate RBF-finite difference (RBF-FD)
formulas. These polynomial basis elements are obtained using the
recently-developed \emph{least orthogonal interpolation} technique (LOI) on
each RBF-FD stencil to obtain \emph{local} restrictions of polynomials in
$\mathbb{R}^3$ to stencils on $\mathbb{M}$. The resulting RBF-LOI method uses
Cartesian coordinates, does not require any intrinsic coordinate systems or
projections of points onto tangent planes, and our tests illustrate robustness
to stagnation errors. We show that our method produces high orders of
convergence for PDEs on the sphere and torus, and present some applications to
reaction-diffusion PDEs motivated by biology.
| math.NA cs.NA |
1807.02776 | Densely Connected CNNs for Bird Audio Detection | Detecting bird sounds in audio recordings automatically, if accurate enough,
is expected to be of great help to the research community working in bio- and
ecoacoustics, interested in monitoring biodiversity based on audio field
recordings. To estimate how accurate the state-of-the-art machine learning
approaches are, the Bird Audio Detection challenge involving large audio
datasets was recently organized. In this paper, experiments using several types
of convolutional neural networks (i.e. standard CNNs, residual nets and densely
connected nets) are reported in the framework of this challenge. DenseNets were
the preferred solution since they were the best performing and most compact
models, leading to a 88.22% area under the receiver operator curve score on the
test set of the challenge. Performance gains were obtained thank to data
augmentation through time and frequency shifting, model parameter averaging
during training and ensemble methods using the geometric mean. On the contrary,
the attempts to enlarge the training dataset with samples of the test set with
automatic predictions used as pseudo-groundtruth labels consistently degraded
performance.
| cs.SD eess.AS |
1807.02777 | A Review of Beam-Driven Plasma Wakefield Experiments | In the past decades, beam-driven plasma wakefield acceleration (PWFA)
experiments have seen remarkable progress by using high-energy particle beams
such as electron, positron and proton beams to drive wakes in neutral gas or
pre-ionized plasma. This review highlights a few recent experiments in the
world to compare experiment parameters and results.
| physics.plasm-ph physics.acc-ph |
1807.02778 | Microcavity enhanced single photon emission from two-dimensional WSe2 | Atomically flat semiconducting materials such as monolayer WSe$_2$ hold great
promise for novel optoelectronic devices. Recently, quantum light emission has
been observed from bound excitons in exfoliated WSe$_2$. As part of developing
optoelectronic devices, the control of the radiative properties of such
emitters is an important step. Here we report the coupling of a bound exciton
in WSe$_2$ to open microcavities. We use a range of radii of curvature in the
plano-concave cavity geometry with mode volumes in the $\lambda^3$ regime,
giving Purcell factors of up to 8 while increasing the photon flux five-fold.
Additionally we determine the quantum efficiency of the single photon emitter
to be $\eta = 0.46 \pm 0.03$. Our findings pave the way to cavity-enhanced
monolayer based single photon sources for a wide range of applications in
nanophotonics and quantum information technologies.
| cond-mat.mes-hall physics.optics |
1807.02779 | Dynamical Systems with a Cyclic Sign Variation Diminishing Property | Several studies analyzed certain nonlinear dynamical systems by showing that
the cyclic number of sign variations in the vector of derivatives is an
integer-valued Lyapunov function. These results are based on direct analysis of
the dynamical equation satisfied by the vector of derivatives, i.e. the
variational system. However, it is natural to assume that they follow from the
fact that the transition matrix in the variational system satisfies a variation
diminishing property (VDP) with respect to the cyclic number of sign variations
in a vector. Motivated by this, we develop the theoretical framework of linear
time-varying systems whose solution satisfies a VDP with respect to the cyclic
number of sign variations. This provides an analogue of the work of Schwarz on
totally positive differential systems, i.e. linear time-varying systems whose
solution satisfies a VDP with respect to the standard (non-cyclic) number of
sign variations.
| math.DS |
1807.02780 | Finding unavoidable colorful patterns in multicolored graphs | We provide multicolored and infinite generalizations for a Ramsey-type
problem raised by Bollob\'as, concerning colorings of $K_n$ where each color is
well-represented. Let $\chi$ be a coloring of the edges of a complete graph on
$n$ vertices into $r$ colors. We call $\chi$ $\varepsilon$-balanced if all
color classes have $\varepsilon$ fraction of the edges. Fix some graph $H$,
together with an $r$-coloring of its edges. Consider the smallest natural
number $R_\varepsilon^r(H)$ such that for all $n\geq R_\varepsilon^r(H)$, all
$\varepsilon$-balanced colorings $\chi$ of $K_n$ contain a subgraph isomorphic
to $H$ in its coloring. Bollob\'as conjectured a simple characterization of $H$
for which $R_\varepsilon^2(H)$ is finite, which was later proved by Cutler and
Mont\'agh. Here, we obtain a characterization for arbitrary values of $r$, as
well as asymptotically tight bounds. We also discuss generalizations to graphs
defined on perfect Polish spaces, where the corresponding notion of
balancedness is each color class being non-meagre.
| math.CO |
1807.02781 | Displacements of automorphisms of free groups I: Displacement functions,
minpoints and train tracks | This is the first of two papers in which we investigate the properties of the
displacement functions of automorphisms of free groups (more generally, free
products) on Culler-Vogtmann Outer space and its simplicial bordification - the
free splitting complex - with respect to the Lipschitz metric. The theory for
irreducible automorphisms being well-developed, we concentrate on the reducible
case. Since we deal with the bordification, we develop all the needed tools in
the more general setting of deformation spaces, and their associated free
splitting complexes.
In the present paper we study the local properties of the displacement
function. In particular, we study its convexity properties and the behaviour at
bordification points, by geometrically characterising its continuity-points. We
prove that the global-simplex-displacement spectrum of $Aut(F_n)$ is a
well-ordered subset of $\mathbb R$, this being helpful for algorithmic
purposes. We introduce a weaker notion of train tracks, which we call {\em
partial train tracks} (which coincides with the usual one for irreducible
automorphisms) and we prove that, for any automorphism, points of minimal
displacement - minpoints - coincide with the marked metric graphs that support
partial train tracks. We show that any automorphism, reducible or not, has a
partial train track (hence a minpoint) either in the outer space or its
bordification. We show that, given an automorphism, any of its invariant free
factors is seen in a partial train track map. In a subsequent paper we will
prove that level sets of the displacement functions are connected, and we will
apply that result to solve certain decision problems.
| math.GR |
1807.02782 | Displacements of automorphisms of free groups II: Connectivity of level
sets and decision problems | This is the second of two papers in which we investigate the properties of
displacement functions of automorphisms of free groups (more generally, free
products) on the Culler-Vogtmann Outer space $CV_n$ and its simplicial
bordification. We develop a theory for both reducible and irreducible
autormorphisms. As we reach the bordification of $CV_n$ we have to deal with
general deformation spaces, for this reason we developed the theory in such
generality. In first paper~\cite{FMpartI} we studied general properties of the
displacement functions, such as well-orderability of the spectrum and the
topological characterization of min-points via partial train tracks (possibly
at infinity). This paper is devoted to proving that for any automorphism
(reducible or not) any level set of the displacement function is connected. As
an application, this result provides a stopping procedure for brute force
search algorithms in $CV_n$. We use this to reprove two known algorithmic
results: the conjugacy problem for irreducible automorphisms and detecting
irreducibility of automorphisms. Note: the two papers were originally packed
together in the preprint arxiv:1703.09945. We decided to split that paper
following the recommendations of a referee.
| math.GR |
1807.02783 | CGC/saturation approach: re-visiting the problem of odd harmonics in
angular correlations | In this paper we demonstrate that the selection of events with different
multiplicities of produced particles, leads to the violation of the azimuthal
angular symmetry, $\phi \to \pi - \phi$. We find for LHC and lower energies,
that this violation can be so large for the events with multiplicities $n \geq
2 \bar{n}$, where $\bar{n}$ is the mean multiplicity, that it leads to almostno
suppression of $v_n$, with odd $n$. However, this can only occur if the typical
size of the dipole in DIS with a nuclear target is small, or $Q^2 \,>\,Q^2_s\Lb
A, Y_{\rm min},b\Rb$, where $Q_s$ is the saturation momentum of the nucleus at
$Y = Y_{\rm min}$. In the case of large sizes of dipoles, when $Q^2
\,<\,Q^2_s\Lb A, Y_{\rm min},b\Rb$, we show that $v_n =0$ for odd $n$.
Hadron-nucleus scattering is discussed.
| hep-ph |
1807.02784 | Discrete quotients of 3-dimensional N = 4 Coulomb branches via the cycle
index | The study of Coulomb branches of 3-dimensional N=4 gauge theories via the
associated Hilbert series, the so-called monopole formula, has been proven
useful not only for 3-dimensional theories, but also for Higgs branches of 5
and 6-dimensional gauge theories with 8 supercharges. Recently, a conjecture
connected different phases of 6-dimensional Higgs branches via gauging of a
discrete global $S_n$ symmetry. On the corresponding 3-dimensional Coulomb
branch, this amounts to a geometric $S_n$-quotient. In this note, we prove the
conjecture on Coulomb branches with unitary nodes and, moreover, extend it to
Coulomb branches with other classical groups. The results promote discrete
$S_n$-quotients to a versatile tool in the study of Coulomb branches.
| hep-th |
1807.02785 | Flowing from 16 to 32 Supercharges | We initiate a study of an infinite set of renormalization group flows with
accidental supersymmetry enhancement. The ultraviolet fixed points are strongly
interacting four-dimensional $\mathcal{N}=2$ superconformal field theories
(SCFTs) with no known Lagrangian descriptions, and the infrared fixed points
are SCFTs with thirty-two (Poincar\'e plus special) supercharges.
| hep-th |
1807.02786 | Graduality from Embedding-projection Pairs (Extended Version) | Gradually typed languages allow statically typed and dynamically typed code
to interact while maintaining benefits of both styles. The key to reasoning
about these mixed programs is Siek-Vitousek-Cimini-Boyland's (dynamic) gradual
guarantee, which says that giving components of a program more precise types
only adds runtime type checking, and does not otherwise change behavior. In
this paper, we give a semantic reformulation of the gradual guarantee called
graduality. We change the name to promote the analogy that graduality is to
gradual typing what parametricity is to polymorphism. Each gives a
local-to-global, syntactic-to-semantic reasoning principle that is formulated
in terms of a kind of observational approximation.
Utilizing the analogy, we develop a novel logical relation for proving
graduality. We show that embedding-projection pairs (ep pairs) are to
graduality what relations are to parametricity. We argue that casts between two
types where one is "more dynamic" (less precise) than the other necessarily
form an ep pair, and we use this to cleanly prove the graduality cases for
casts from the ep-pair property. To construct ep pairs, we give an analysis of
the type dynamism relation (also known as type precision or naive subtyping)
that interprets the rules for type dynamism as compositional constructions on
ep pairs, analogous to the coercion interpretation of subtyping.
| cs.PL |
1807.02787 | Financial Trading as a Game: A Deep Reinforcement Learning Approach | An automatic program that generates constant profit from the financial market
is lucrative for every market practitioner. Recent advance in deep
reinforcement learning provides a framework toward end-to-end training of such
trading agent. In this paper, we propose an Markov Decision Process (MDP) model
suitable for the financial trading task and solve it with the state-of-the-art
deep recurrent Q-network (DRQN) algorithm. We propose several modifications to
the existing learning algorithm to make it more suitable under the financial
trading setting, namely 1. We employ a substantially small replay memory (only
a few hundreds in size) compared to ones used in modern deep reinforcement
learning algorithms (often millions in size.) 2. We develop an action
augmentation technique to mitigate the need for random exploration by providing
extra feedback signals for all actions to the agent. This enables us to use
greedy policy over the course of learning and shows strong empirical
performance compared to more commonly used epsilon-greedy exploration. However,
this technique is specific to financial trading under a few market assumptions.
3. We sample a longer sequence for recurrent neural network training. A side
product of this mechanism is that we can now train the agent for every T steps.
This greatly reduces training time since the overall computation is down by a
factor of T. We combine all of the above into a complete online learning
algorithm and validate our approach on the spot foreign exchange market.
| q-fin.TR cs.LG stat.ML |
1807.02788 | Bioadhesive Graft-Antenna for Stimulation and Repair of Peripheral
Nerves | Peripheral nerve injuries are difficult to treat due to limited axon
regeneration; brief electrical stimulation of injured nerves is an emerging
therapy that can relieve pain and enhance regeneration. We report an original
wireless stimulator based on a metal loop (diameter ~1 mm) that is powered by a
transcranial magnetic stimulator (TMS). The loop can be integrated in a
chitosan scaffold that functions as a graft when applied onto transected nerves
(graft-antenna). The graft-antenna was bonded to rat sciatic nerves by a laser
without sutures; it did not migrate after implantation and was able to trigger
steady compound muscle action potentials for 12 weeks (CMAP ~1.3 mV). Eight
weeks post-operatively, axon regeneration was facilitated in transected nerves
that were repaired with the graft-antenna and stimulated by the TMS for 1
hour/week. The graft-antenna is an innovative and minimally-invasive device
that functions concurrently as a wireless stimulator and adhesive scaffold for
nerve repair.
| physics.med-ph |
1807.02789 | The modal age of Statistics | Recently, a number of statistical problems have found an unexpected solution
by inspecting them through a "modal point of view". These include classical
tasks such as clustering or regression. This has led to a renewed interest in
estimation and inference for the mode. This paper offers an extensive survey of
the traditional approaches to mode estimation and explores the consequences of
applying this modern modal methodology to other, seemingly unrelated, fields.
| stat.ME stat.ML |
1807.02790 | On the complexity of quasiconvex integer minimization problem | In this paper, we consider the class of quasiconvex functions and its proper
subclass of conic functions. The integer minimization problem of these
functions is considered in the paper, assuming that an optimized function is
defined by the comparison oracle. We will show that there is no a polynomial
algorithm on $\log R$ to optimize quasiconvex functions in the ball of integer
radius $R$ using only the comparison oracle. On the other hand, if an optimized
function is conic, then we show that there is a polynomial on $\log R$
algorithm. We also present an exponential on the dimension lower bound for the
oracle complexity of the conic function integer optimization problem.
Additionally, we give examples of known problems that can be polynomially
reduced to the minimization problem of functions in our classes.
| math.OC cs.CC |
1807.02791 | Is breaking of ensemble equivalence monotone in the number of
constraints? | Breaking of ensemble equivalence between the microcanonical ensemble and the
canonical ensemble may occur for random graphs whose size tends to infinity,
and is signaled by a non-zero specific relative entropy of the two ensembles.
In [3] and [4] it was shown that breaking occurs when the constraint is put on
the degree sequence (configuration model). It is not known what is the effect
on the relative entropy when the number of constraints is reduced, i.e., when
only part of the nodes are constrained in their degree (and the remaining nodes
are left unconstrained). Intuitively, the relative entropy is expected to
decrease. However, this is not a trivial issue because when constraints are
removed both the microcanonical ensemble and the canonical ensemble change. In
this paper a formula for the relative entropy valid for generic discrete random
structures, recently formulated by Squartini and Garlaschelli, is used to prove
that the relative entropy is monotone in the number of constraints when the
constraint is on the degrees of the nodes. It is further shown that the
expression for the relative entropy corresponds, in the dense regime, to the
degrees in the microcanonical ensemble being asymptotically multivariate Dirac
and in the canonical ensemble being asymptotically Gaussian.
| cond-mat.stat-mech math-ph math.MP |