title: Learning zero-cost portfolio selection with pattern matching

abstract:
  We consider and extend the adversarial agent-based learning approach of
Gy{\"o}rfi {\it et al} to the situation of zero-cost portfolio selection
implemented with a quadratic approximation derived from the mutual fund
separation theorems. The algorithm is applied to daily sampled sequential
Open-High-Low-Close data and sequential intraday 5-minute bar-data from the
Johannesburg Stock Exchange (JSE). Statistical tests of the algorithms are
considered. The algorithms are directly compared to standard NYSE test cases
from prior literature. The learning algorithm is used to select parameters for
agents (or experts) generated by pattern matching past dynamics using a simple
nearest-neighbour search algorithm. It is shown that there is a speed advantage
associated with using an analytic solution of the mutual fund separation
theorems. It is argued that the expected loss in performance does not undermine
the potential application to intraday quantitative trading and that when
transactions costs and slippage are considered the strategies can still remain
profitable when unleveraged. The paper demonstrates that patterns in financial
time-series on the JSE can be systematically exploited in collective but that
this does not imply predictability of the individual asset time-series
themselves.


title: Expected communication cost of distributed quantum tasks

abstract:
  A central question in classical information theory is that of source
compression, which is the task where Alice receives a sample from a known
probability distribution and needs to transmit it to the receiver Bob with
small error. This problem has a one-shot solution due to Huffman, in which the
messages are of variable length and the expected length of the messages matches
the asymptotic and i.i.d. compression rate of the Shannon entropy of the
source.
  In this work, we consider a quantum extension of above task, where Alice
receives a sample from a known probability distribution and needs to transmit a
part of a pure quantum state (that is associated to the sample) to Bob. We
allow entanglement assistance in the protocol, so that the communication is
possible through classical messages, for example using quantum teleportation.
The classical messages can have a variable length and the goal is to minimize
their expected length. We provide a characterization of the expected
communication cost of this task, by giving a lower bound that is near optimal
up to some additive factors.
  A special case of above task, and the quantum analogue of the source
compression problem, is when Alice needs to transmit the whole of her pure
quantum state. Here we show that there is no one-shot interactive scheme which
matches the asymptotic and i.i.d. compression rate of the von Neumann entropy
of the average quantum state. This is a relatively rare case in quantum
information theory where the cost of a quantum task is significantly different
from its classical analogue. Further, we also exhibit similar results for the
fully quantum task of quantum state redistribution, employing some different
techniques. We show implications for the one-shot version of the problem of
quantum channel simulation.


title:
Spectrum and Infrastructure Sharing in Millimeter Wave Cellular
  Networks: An Economic Perspective

abstract:
  The licensing model for millimeter wave bands has been the subject of
considerable debate, with some industry players advocating for unlicensed use
and others for traditional geographic area exclusive use licenses. Meanwhile,
the massive bandwidth, highly directional antennas, high penetration loss and
susceptibility to shadowing in these bands suggest certain advantages to
spectrum and infrastructure sharing. However, even when sharing is technically
beneficial (as recent research in this area suggests that it is), it may not be
profitable. In this paper, both the technical and economic implications of
resource sharing in millimeter wave networks are studied. Millimeter wave
service is considered in the economic framework of a network good, where
consumers' utility depends on the size of the network, and the strategic
decisions of consumers and service providers are connected to detailed network
simulations. The results suggest that "open" deployments of neutral small cells
that serve subscribers of any service provider encourage market entry by making
it easier for networks to reach critical mass, more than "open" (unlicensed)
spectrum would. The conditions under which competitive service providers would
prefer to share resources or not are also described.


title: Improving the Neural Algorithm of Artistic Style

abstract:
  In this work we investigate different avenues of improving the Neural
Algorithm of Artistic Style (by Leon A. Gatys, Alexander S. Ecker and Matthias
Bethge, arXiv:1508.06576).
  While showing great results when transferring homogeneous and repetitive
patterns, the original style representation often fails to capture more complex
properties, like having separate styles of foreground and background. This
leads to visual artifacts and undesirable textures appearing in unexpected
regions when performing style transfer.
  We tackle this issue with a variety of approaches, mostly by modifying the
style representation in order for it to capture more information and impose a
tighter constraint on the style transfer result.
  In our experiments, we subjectively evaluate our best method as producing
from barely noticeable to significant improvements in the quality of style
transfer.


title: A dynamical polynomial chaos approach for long-time evolution of SPDEs

abstract:
  We propose a Dynamical generalized Polynomial Chaos (DgPC) method to solve
time-dependent stochastic partial differential equations (SPDEs) with white
noise forcing. The long-time simulation of SPDE solutions by Polynomial Chaos
(PC) methods is notoriously difficult as the dimension of the stochastic
variables increases linearly with time. Exploiting the markovian property of
white noise, DgPC [1] implements a restart procedure that allows us to expand
solutions at future times in terms of orthogonal polynomials of the measure
describing the solution at a given time and the future white noise. The
dimension of the representation is kept minimal by application of a
Karhunen--Loeve (KL) expansion. Using frequent restarts and low degree
polynomials on sparse multi-index sets, the method allows us to perform long
time simulations, including the calculation of invariant measures for systems
which possess one. We apply the method to the numerical simulation of
stochastic Burgers and Navier--Stokes equations with white noise forcing. Our
method also allows us to incorporate time-independent random coefficients such
as a random viscosity. We propose several numerical simulations and show that
the algorithm compares favorably with standard Monte Carlo methods.


title:
A universal energy distribution function for repeating fast radio
  bursts?

abstract:
  Assuming: fast radio bursts (FRBs) are produced by neutron stars at
cosmological distances; FRB rate tracks core-collapse supernova rate; and all
FRBs repeat with a universal energy distribution function (EDF) dN/dE ~
E^(-beta) with a high-end cutoff at burst energy E_max. We find that
observations so far are consistent with a universal EDF with a power-law index
1.5 < beta < 2.2, high-end cutoff E_max/E_0 > 30 and normalization N_0 < 2 per
day; where N_0 is the integrated rate above the reference burst energy E_0 =
1.2e39 f_r^(-1) erg (f_r is the radio emission efficiency). Implications of
such an EDF are discussed.


title:
$\mathbf{k}_0$ of semiartinian von Neumann regular rings. Direct
  finiteness versus unit-regularity

abstract:
  If $R$ is a regular and semiartinian ring, it is proved that the following
conditions are equivalent: (1) $R$ is unit-regular, (2) every factor ring of
$R$ is directly finite, (3) the abelian group $K_0(R)$ is free and admits a
basis which is in a canonical one to one correspondence with a set of
representatives of simple right $R$-modules. For the class of semiartinian and
unit-regular rings the canonical partial order of $K_0(R)$ is investigated and
the directed abelian groups which are realizable as $K_0(R)$ of these rings are
classified.


title:
Nature and statistical properties of quasar associated absorption
  systems in the XQ-100 Legacy Survey

abstract:
  We statistically study the physical properties of a sample of narrow
absorption line (NAL) systems looking for empirical evidences to distinguish
between intrinsic and intervening NALs without taking into account any a priori
definition or velocity cut-off. We analyze the spectra of 100 quasars with 3.5
< z$\rm_{em}$ < 4.5, observed with X-shooter/VLT in the context of the XQ-100
Legacy Survey. We detect a $\sim$ 8 $\sigma$ excess in the number density of
absorbers within 10,000 km/s of the quasar emission redshift with respect to
the random occurrence of NALs. This excess does not show a dependence on the
quasar bolometric luminosity and it is not due to the redshift evolution of
NALs. It extends far beyond the standard 5000 km/s cut-off traditionally
defined for associated absorption lines. We propose to modify this definition,
extending the threshold to 10,000 km/s when also weak absorbers (equivalent
width < 0.2 \AA) are considered. We infer NV is the ion that better traces the
effects of the quasar ionization field, offering the best statistical tool to
identify intrinsic systems. Following this criterion we estimate that the
fraction of quasars in our sample hosting an intrinsic NAL system is 33
percent. Lastly, we compare the properties of the material along the quasar
line of sight, derived from our sample, with results based on close quasar
pairs investigating the transverse direction. We find a deficiency of cool gas
(traced by CII) along the line of sight associated with the quasar host galaxy,
in contrast with what is observed in the transverse direction.


title:
Search for supersymmetry in pp collisions at sqrt(s) = 13 TeV in the
  single-lepton final state using the sum of masses of large-radius jets

abstract:
  Results are reported from a search for supersymmetric particles in
proton-proton collisions in the final state with a single, high transverse
momentum lepton; multiple jets, including at least one b-tagged jet; and large
missing transverse momentum. The data sample corresponds to an integrated
luminosity of 2.3 inverse femtobarns at sqrt(s) = 13 TeV, recorded by the CMS
experiment at the LHC. The search focuses on processes leading to high jet
multiplicities, such as gluino pair production with gluinos to t t-bar
neutralino[1]. The quantity M[J], defined as the sum of the masses of the
large-radius jets in the event, is used in conjunction with other kinematic
variables to provide discrimination between signal and background and as a key
part of the background estimation method. The observed event yields in the
signal regions in data are consistent with those expected for standard model
backgrounds, estimated from control regions in data. Exclusion limits are
obtained for a simplified model corresponding to gluino pair production with
three-body decays into top quarks and neutralinos. Gluinos with a mass below
1600 GeV are excluded at a 95% confidence level for scenarios with low
neutralino[1] mass, and neutralinos with a mass below 800 GeV are excluded for
a gluino mass of about 1300 GeV. For models with two-body gluino decays
producing on-shell top squarks, the excluded region is only weakly sensitive to
the top squark mass.


title: The Stable Roommates problem with short lists

abstract:
  We consider two variants of the classical Stable Roommates problem with
Incomplete (but strictly ordered) preference lists SRI that are degree
constrained, i.e., preference lists are of bounded length. The first variant,
EGAL d-SRI, involves finding an egalitarian stable matching in solvable
instances of SRI with preference lists of length at most d. We show that this
problem is NP-hard even if d=3. On the positive side we give a
(2d+3)/7-approximation algorithm for d={3,4,5} which improves on the known
bound of 2 for the unbounded preference list case. In the second variant of
SRI, called d-SRTI, preference lists can include ties and are of length at most
d. We show that the problem of deciding whether an instance of d-SRTI admits a
stable matching is NP-complete even if d=3. We also consider the "most stable"
version of this problem and prove a strong inapproximability bound for the d=3
case. However for d=2 we show that the latter problem can be solved in
polynomial time.


title:
QCD corrections to vector boson pair production in gluon fusion
  including interference effects with off-shell Higgs at the LHC

abstract:
  We compute next-to-leading order (NLO) QCD corrections to the production of
two massive electroweak bosons in gluon fusion. We consider both the prompt
production process $gg \to VV$ and the production mediated by an exchange of an
s-channel Higgs boson, $gg \to H^* \to V V$. We include final states with both
on- and off-shell vector bosons with leptonic decays. The gluonic production of
vector bosons is a loop-induced process, including both massless and massive
quarks in the loop. For $gg \to ZZ$ production, we obtain the NLO QCD
corrections to the massive loops through an expansion around the heavy top
limit. This approximation is valid below the top production threshold, giving a
broad range of invariant masses between the Higgs production and the top
production thresholds in which our results are valid. We explore the NLO QCD
effects in $gg \to ZZ$ focusing, in particular, on the interference between
prompt and Higgs-mediated processes. We find that the QCD corrections to the
interference are large and similar in size to the corrections to both the
signal and the background processes. At the same time, we observe that
corrections to the interference change rapidly with the four-lepton invariant
mass in the region around the ZZ production threshold. We also study the
interference effects in $gg \to WW$ production where, due to technical
limitations, we only consider contributions of massless loops. We find that the
QCD corrections to the interference in this case are somewhat larger than those
for either the signal or the background.


title:
Efficiently decodable insertion/deletion codes for high-noise and
  high-rate regimes

abstract:
  This work constructs codes that are efficiently decodable from a constant
fraction of \emph{worst-case} insertion and deletion errors in three parameter
settings: (i) Binary codes with rate approaching 1; (ii) Codes with constant
rate for error fraction approaching 1 over fixed alphabet size; and (iii)
Constant rate codes over an alphabet of size $k$ for error fraction approaching
$(k-1)/(k+1)$. When errors are constrained to deletions alone, efficiently
decodable codes in each of these regimes were constructed recently. We complete
the picture by constructing similar codes that are efficiently decodable in the
insertion/deletion regime.


title: Electrophobic Scalar Boson and Muonic Puzzles

abstract:
  A new scalar boson which couples to the muon and proton can simultaneously
solve the proton radius puzzle and the muon anomalous magnetic moment
discrepancy. Using a variety of measurements, we constrain the mass of this
scalar and its couplings to the electron, muon, neutron, and proton. Making no
assumptions about the underlying model, these constraints and the requirement
that it solve both problems limit the mass of the scalar to between about 100
keV and 100 MeV. We identify two unexplored regions in the coupling
constant-mass plane. Potential future experiments and their implications for
theories with mass-weighted lepton couplings are discussed.

categories: hep-ph hep-ex nucl-ex nucl-th physics.atom-ph


title: Nearly massless Dirac fermions hosted by Sb square net in BaMnSb2

abstract:
  Layered compounds AMnBi2 (A=Ca, Sr, Ba, or rare earth element) have been
established as Dirac materials. Dirac electrons generated by the
two-dimensional (2D) Bi square net in these materials are normally massive due
to the presence of a spin-orbital coupling (SOC) induced gap at Dirac nodes.
Here we report that the Sb square net in an isostructural compound BaMnSb2 can
host nearly massless Dirac fermions. We observed strong Shubnikov-de Haas (SdH)
oscillations in this material. From the analyses of the SdH oscillations, we
find key signatures of Dirac fermions, including light effective mass
(~0.052m0; m0, mass of free electron), high quantum mobility (1280 cm2V-1S-1)
and a Pi Berry phase accumulated along cyclotron orbit. Compared with AMnBi2,
BaMnSb2 also exhibits much more significant quasi two-dimensional (2D)
electronic structure, with the out-of-plane transport showing nonmetallic
conduction below 120K and the ratio of the out-of-plane and in-plane
resistivity reaching ~670. Additionally, BaMnSb2 also exhibits an
antiferromagnetic order with a weak ferromagnetic component. The combination of
nearly massless Dirac fermions on quasi-2D planes with a magnetic order makes
BaMnSb2 an intriguing platform for seeking novel exotic phenomena of massless
Dirac electrons.


title:
DeepLearningKit - an GPU Optimized Deep Learning Framework for Apple's
  iOS, OS X and tvOS developed in Metal and Swift

abstract:
  In this paper we present DeepLearningKit - an open source framework that
supports using pretrained deep learning models (convolutional neural networks)
for iOS, OS X and tvOS. DeepLearningKit is developed in Metal in order to
utilize the GPU efficiently and Swift for integration with applications, e.g.
iOS-based mobile apps on iPhone/iPad, tvOS-based apps for the big screen, or OS
X desktop applications. The goal is to support using deep learning models
trained with popular frameworks such as Caffe, Torch, TensorFlow, Theano,
Pylearn, Deeplearning4J and Mocha. Given the massive GPU resources and time
required to train Deep Learning models we suggest an App Store like model to
distribute and download pretrained and reusable Deep Learning models.


title: Fusion systems with some sporadic J-components

abstract:
  Aschbacher's program for the classification of simple fusion systems of "odd"
type at the prime 2 has two main stages: the classification of 2-fusion systems
of subintrinsic component type and the classification of 2-fusion systems of
J-component type. We make a contribution to the latter stage by classifying
2-fusion systems with a J-component isomorphic to the 2-fusion systems of
several sporadic groups under the assumption that the centralizer of such a
component is cyclic.


title:
The Cauchy problem for the nonlinear damped wave equation with slowly
  decaying data

abstract:
  We study the Cauchy problem for the nonlinear damped wave equation and
establish the large data local well-posedness and small data global
well-posedness with slowly decaying initial data. We also prove that the
asymptotic profile of the global solution is given by a solution of the
corresponding parabolic problem, which shows that the solution of the damped
wave equation has the diffusion phenomena. Moreover, we show blow-up of
solution and give the estimate of the lifespan for a subcritical nonlinearity.
In particular, we determine the critical exponent for any space dimension.


title:
Transformation theory and Christoffel formulas for matrix biorthogonal
  polynomials on the real line

abstract:
  In this paper transformations for matrix orthogonal polynomials in the real
line are studied. The orthogonality is understood in a broad sense, and is
given in terms of a nondegenerate continuous sesquilinear form, which in turn
is determined by a quasidefinite matrix of bivariate generalized functions with
a well defined support. The discussion of the orthogonality for such a
sesquilinear form includes, among others, matrix Hankel cases with linear
functionals, general matrix Sobolev orthogonality and discrete orthogonal
polynomials with an infinite support. The first transformation considered is
that of Geronimus type, two different methods are developed. A spectral one,
based on the spectral properties of the perturbing polynomial, and constructed
in terms of the second kind functions. Then, using spectral techniques and
spectral jets, Christoffel-Geronimus formulas for the transformed polynomials
and norms are presented. For this type of transformations, the paper also
proposes an alternative method, which does not require of spectral techniques.
A discussion on matrix spectral linear transformations is presented, as well.
These transformations can be understood as rational perturbations of the matrix
of bivariate generalized functions together with an addition of appropriate
masses, determined these last ones by the spectral properties of the polynomial
denominator. As for the Geronimus case, two techniques are applied, spectral
and mixed spectral/nonspectral. Christoffel--Geronimus--Uvarov formulas are
found with both approaches and some applications are given. The transformation
theory is finally discussed in the context of the 2D non-Abelian Toda lattice
and noncommutative KP hierarchies, understood as the theory of continuous
transformations of quasidefinite sesquilinear forms. This approach allows for
the finding of perturbed quasitau and Baker matrices.

categories: math.CA math-ph math.MP math.RA math.SP nlin.SI


title: Fine Structure Zonal Flow Excitation by Beta-induced Alfven Eigenmode

abstract:
  Nonlinear excitation of low frequency zonal structure (LFZS) by beta-induced
Alfven eigenmode (BAE) is investigated using nonlinear gyrokinetic theory. It
is found that electrostatic zonal flow (ZF), rather than zonal current, is
preferentially excited by finite amplitude BAE. In addition to the well-known
meso-scale radial envelope structure, ZF is also found to exhibit fine radial
structure due to the localization of BAE with respect to mode rational
surfaces. Specifically, the zonal electric field has an even mode structure at
the rational surface where radial envelope peaks.


title: An end-to-end assembly of the Aedes aegypti genome

abstract:
  We present an end-to-end genome assembly of a female Aedes aegypti mosquito,
which spreads viral diseases such as yellow fever, dengue, chikungunya, and
Zika to humans. The assembly is based on an earlier genome published in 2007
and improved in 2013. The new assembly has a scaffold N50 of 419Mb, with 96.9%
of the ungapped sequence anchored to chromosomes. We used the new assembly to
examine the conservation of A. aegypti chromosomes. Our results suggest that
synteny is strongly conserved between Ae. aegypti and An. gambiae. Comparison
to D. melanogaster highlights the extent to which the identity of entire
chromosome arms is preserved across dipterans.


title: A consistent flow of entropy

abstract:
  A common approach to evaluate entropy in quantum systems is to solve a
master-Bloch equation to determine density matrix and substitute it in entropy
definition. However, this method has been recently understood to lack many
energy correlators. The new correlators make entropy evaluation to be different
from the substitution method described above. The reason for such complexity
lies in the nonlinearity of entropy. In this paper we present a pedagogical
approach to evaluate the new correlators and explain their contribution in the
analysis. We show that the inherent nonlinearity in entropy makes the second
law of thermodynamics to carry new terms associated to the new correlators. Our
results show important new remarks on quantum black holes. Our formalism
reveals that the notion of degeneracy of states at the event horizon makes an
indispensable deviation from black hole entropy in the leading order.


title: Phase separation in LuFeO3 films

abstract:
  The structural transition at about 1000 {\deg}C, from the hexagonal to the
orthorhombic phase of LuFeO3, has been investigated in thin films of LuFeO3.
Separation of the two structural phases of LuFeO3 occurs on a length scale of
micrometer, as visualized in real space using X-ray photoemission electron
microscopy (X-PEEM). The results are consistent with X-ray diffraction and
atomic force microscopy obtained from LuFeO3 thin films undergoing the
irreversible structural transition from the hexagonal to the orthorhombic phase
of LuFeO3, at elevated temperatures. The sharp phase boundaries between the
structural phases are observed to align with the crystal planes of the
hexagonal LuFeO3 phase. The coexistence of different structural domains
indicates that the irreversible structural transition, from the hexagonal to
the orthorhombic phase in LuFeO3, is a first order transition, for epitaxial
hexagonal LuFeO3 films grown on Al2O3.


title:
Spectroscopic Studies of the Physical Origin of Environmental Aging
  Effects on Doped Graphene

abstract:
  The environmental aging effect of doped graphene is investigated as a
function of the organic doping species, humidity, and the number of graphene
layers adjacent to the dopant by studies of the Raman spectroscopy, x-ray and
ultraviolet photoelectron spectroscopy, scanning electron microscopy, infrared
spectroscopy, and electrical transport measurements. It is found that higher
humidity and structural defects induce faster degradation in doped graphene.
Detailed analysis of the spectroscopic data suggest that the physical origin of
the aging effect is associated with the continuing reaction of H2O molecules
with the hygroscopic organic dopants, which leads to formation of excess
chemical bonds, reduction in the doped graphene carrier density, and
proliferation of damages from the graphene grain boundaries. These
environmental aging effects are further shown to be significantly mitigated by
added graphene layers.


title:
Comparison between Fermion Bag Approach and Complex Langevin Dynamics
  for Massive Thirring Model at Finite Density in 0 + 1 Dimensions

abstract:
  We consider the massive Thirring model at finite density in 0+1 dimension.
The fermion bag approach, Langevin dynamics and complex Langevin dynamics are
adopted to attack the sign problem for this model. Compared with the complex
Langevin dynamics, both fermion bag approach and Langvin dynamics avoid the
sign problem. The fermion density and chiral condensate, which are obtained by
these numerical methods, are compared with the exact results. The advantages of
the fermion bag approach over the other numerical methods are also discussed.


title: Learning to Rank Personalized Search Results in Professional Networks

abstract:
  LinkedIn search is deeply personalized - for the same queries, different
searchers expect completely different results. This paper presents our approach
to achieving this by mining various data sources available in LinkedIn to infer
searchers' intents (such as hiring, job seeking, etc.), as well as extending
the concept of homophily to capture the searcher-result similarities on many
aspects. Then, learning-to-rank (LTR) is applied to combine these signals with
standard search features.


title:
Higgs bundles over cell complexes and representations of finitely
  generated groups

abstract:
  The purpose of this paper is to extend the Donaldson-Corlette theorem to the
case of vector bundles over cell complexes. We define the notion of a vector
bundle and a Higgs bundle over a complex, and describe the associated Betti, de
Rham and Higgs moduli spaces. The main theorem is that the $SL(r, \mathbb{C})$
character variety of a finitely presented group $\Gamma$ is homeomorphic to the
moduli space of rank $r$ Higgs bundles over an admissible complex $X$ with
$\pi_1(X) = \Gamma$. A key role is played by the theory of harmonic maps
defined on singular domains.


title: On the Gap Between Decentralized and Centralized Coded Caching Schemes

abstract:
  Caching is a promising solution to satisfy the ongoing explosive demands for
multi-media traffics. Recently, Maddah-Ali and Niesen proposed both centralized
and de-centralized coded caching schemes, which are able to attain significant
performance gains over uncoded caching schemes. Particular, their work
indicates that there exists a performance gap between the decentralized coded
caching scheme and the centralized coded caching scheme. In this paper, we
investigate this gap. As a result, we prove that the multiplicative gap (i.e.,
the ratio of their performances) is between 1 and 1:5. The upper bound tightens
the original one of 12 by Maddah-Ali and Niesen, while the lower bound verifies
the intuition that the centralized coded caching scheme always outperforms its
decentralized counterpart. Notably, both bounds are achievable in some cases.
Furthermore, we prove that the gap can be arbitrarily close to 1 if the number
of users is large enough, which suggests the great potential in practical
applications to use the less optimal but more practical decentralized coded
caching scheme


title:
Broadband, large-area microwave antenna for optically-detected magnetic
  resonance of nitrogen-vacancy centers in diamond

abstract:
  We report on a microwave planar ring antenna specifically designed for
optically-detected magnetic resonance (ODMR) of nitrogen-vacancy (NV) centers
in diamond. It has the resonance frequency at around 2.87 GHz with the
bandwidth of 400 MHz, ensuring that ODMR can be observed under external
magnetic fields up to 100 G without the need of adjustment of the resonance
frequency. It is also spatially uniform within the 1-mm-diameter center hole,
enabling the magnetic-field imaging in the wide spatial range. These features
facilitate the experiments on quantum sensing and imaging using NV centers at
room temperature.


title:
Equivalence of the logarithmically averaged Chowla and Sarnak
  conjectures

abstract:
  Let $\lambda$ denote the Liouville function. The Chowla conjecture asserts
that $$ \sum_{n \leq X} \lambda(a_1 n + b_1) \lambda(a_2 n+b_2) \dots
\lambda(a_k n + b_k) = o_{X \to \infty}(X) $$ for any fixed natural numbers
$a_1,a_2,\dots,a_k$ and non-negative integer $b_1,b_2,\dots,b_k$ with
$a_ib_j-a_jb_i \neq 0$ for all $1 \leq i < j \leq k$, and any $X \geq 1$. This
conjecture is open for $k \geq 2$. As is well known, this conjecture implies
the conjecture of Sarnak that $$ \sum_{n \leq X} \lambda(n) f(n) = o_{X \to
\infty}(X)$$ whenever $f : {\bf N} \to {\bf C}$ is a fixed deterministic
sequence and $X \geq 1$. In this paper, we consider the weaker logarithmically
averaged versions of these conjectures, namely that $$ \sum_{X/\omega \leq n
\leq X} \frac{\lambda(a_1 n + b_1) \lambda(a_2 n+b_2) \dots \lambda(a_k n +
b_k)}{n} = o_{\omega \to \infty}(\log \omega) $$ and $$ \sum_{X/\omega \leq n
\leq X} \frac{\lambda(n) f(n)}{n} = o_{\omega \to \infty}(\log \omega)$$ under
the same hypotheses on $a_1,\dots,a_k,b_1,\dots,b_k$ and $f$, and for any $2
\leq \omega \leq X$. Our main result is that these latter two conjectures are
logically equivalent to each other, as well as to the "local Gowers uniformity"
of the Liouville function. The main tools used here are the entropy decrement
argument of the author used recently to establish the $k=2$ case of the
logarithmically averaged Chowla conjecture, as well as the inverse conjecture
for the Gowers norms, obtained by Green, Ziegler, and the author.


title: Implementing black hole as efficient power plant

abstract:
  Treating the black hole molecules as working substance and considering its
phase structure, we study the black hole heat engine by a charged anti-de
Sitter black hole. In the reduced temperature-entropy chart, it is found that
the work, heat, and efficiency of the engine are free of the black hole charge.
Applying the Rankine cycle with or without a back pressure mechanism to the
black hole heat engine, the compact formula for the efficiency is obtained. And
the heat, work and efficiency are worked out. The result shows that the black
hole engine working along the Rankine cycle with a back pressure mechanism has
a higher efficiency. This provides a novel and efficient mechanism to produce
the useful mechanical work, and such black hole heat engine may act as a
possible energy source for the high energy astrophysical phenomena near the
black hole.


title:
Logarithmic conformal field theory, log-modular tensor categories and
  modular forms

abstract:
  The two pillars of rational conformal field theory and rational vertex
operator algebras are modularity of characters on the one hand and its
interpretation of modules as objects in a modular tensor category on the other
one. Overarching these pillars is the Verlinde formula.
  In this paper we consider the more general class of logarithmic conformal
field theories and $C_2$-cofinite vertex operator algebras. We suggest that
their modular pillar are trace functions with insertions corresponding to
intertwiners of the projective cover of the vacuum, and that the categorical
pillar are finite tensor categories $\mathcal C$ which are ribbon and whose
double is isomorphic to the Deligne product $\mathcal C\otimes \mathcal
C^{opp}$.
  Overarching these pillars is then a logarithmic variant of Verlinde's
formula. Numerical data realizing this are the modular $S$-matrix and modified
traces of open Hopf links.
  The representation categories of $C_2$-cofinite and logarithmic conformal
field theories that are fairly well understood are those of the $\mathcal
W_p$-triplet algebras and the symplectic fermions. We illustrate the ideas in
these examples and especially make the relation between logarithmic Hopf links
and modular transformations explicit.


title: On reduced stable pair invariants

abstract:
  Let $X = S \times E$ be the product of a K3 surface $S$ and an elliptic curve
$E$. Reduced stable pair invariants of $X$ can be defined via (1) cutting down
the reduced virtual class with incidence conditions or (2) the Behrend function
weighted Euler characteristic of the quotient of the moduli space by the
translation action of $E$. We show that (2) arises naturally as the degree of a
virtual class, and that the invariants (1) and (2) agree. This has applications
to deformation invariance, rationality and a DT/PT correspondence for reduced
invariants of $S \times E$.


title: Multi-step nucleation of nanocrystals in aqueous solution

abstract:
  Nucleation and growth of solids from solutions impacts many natural processes
and are fundamental to applications in materials engineering and medicine. For
a crystalline solid, the nucleus is a nanoscale cluster of ordered atoms, which
forms through mechanisms that are still poorly understood. These mechanisms
have important consequences on the morphology and nucleation rates of the
resultant crystals but it is unclear whether a nucleus forms spontaneously from
solution in a single step or through multiple steps. Using in-situ electron
microscopy, we observe and quantify how gold and silver nanocrystals nucleate
from a supersaturated aqueous gold and silver solution in three distinct steps:
(I) spinodal decomposition into solute-rich and solute-poor liquid phases, (II)
nucleation of amorphous gold nanoclusters within the gold-rich liquid phase,
followed by (III) crystallization of these amorphous clusters. Our ab-initio
calculations on gold nucleation suggest that these steps might be associated
with strong gold-gold atom coupling and water-mediated metastable gold
complexes. The understanding of intermediate steps in nuclei formation has
important implications for the formation and growth of both crystalline and
amorphous materials.


title:
Distillation of logic-qubit entanglement assisted with cross-Kerr
  nonlinearity

abstract:
  Logic-qubit entanglement has attracted much attention in both quantum
communication and quantum computation. Here, we present an efficient protocol
to distill the logic-qubit entanglement with the help of cross-Kerr
nonlinearity. This protocol not only can purify the logic bit-flip error and
logic phase-flip error, but also can correct the physical bit-flip error
completely. We use cross-Kerr nonlinearity to construct quantum nondemolition
detectors. Our distillation protocol for logic-qubit entanglement may be useful
for the practical applications in quantum information, especially in
long-distance quantum communication.


title:
Heart Beat Characterization from Ballistocardiogram Signals using
  Extended Functions of Multiple Instances

abstract:
  A multiple instance learning (MIL) method, extended Function of Multiple
Instances ($e$FUMI), is applied to ballistocardiogram (BCG) signals produced by
a hydraulic bed sensor. The goal of this approach is to learn a personalized
heartbeat "concept" for an individual. This heartbeat concept is a prototype
(or "signature") that characterizes the heartbeat pattern for an individual in
ballistocardiogram data. The $e$FUMI method models the problem of learning a
heartbeat concept from a BCG signal as a MIL problem. This approach elegantly
addresses the uncertainty inherent in a BCG signal e. g., misalignment between
training data and ground truth, mis-collection of heartbeat by some
transducers, etc. Given a BCG training signal coupled with a ground truth
signal (e.g., a pulse finger sensor), training "bags" labeled with only binary
labels denoting if a training bag contains a heartbeat signal or not can be
generated. Then, using these bags, $e$FUMI learns a personalized concept of
heartbeat for a subject as well as several non-heartbeat background concepts.
After learning the heartbeat concept, heartbeat detection and heart rate
estimation can be applied to test data. Experimental results show that the
estimated heartbeat concept found by $e$FUMI is more representative and a more
discriminative prototype of the heartbeat signals than those found by
comparison MIL methods in the literature.


title: Cumulative Activation in Social Networks

abstract:
  Most studies on influence maximization focus on one-shot propagation, i.e.
the influence is propagated from seed users only once following a probabilistic
diffusion model and users' activation are determined via single cascade. In
reality it is often the case that a user needs to be cumulatively impacted by
receiving enough pieces of information propagated to her before she makes the
final purchase decision. In this paper we model such cumulative activation as
the following process: first multiple pieces of information are propagated
independently in the social network following the classical independent cascade
model, then the user will be activated (and adopt the product) if the
cumulative pieces of information she received reaches her cumulative activation
threshold. Two optimization problems are investigated under this framework:
seed minimization with cumulative activation (SM-CA), which asks how to select
a seed set with minimum size such that the number of cumulatively active nodes
reaches a given requirement $\eta$; influence maximization with cumulative
activation (IM-CA), which asks how to choose a seed set with fixed budget to
maximize the number of cumulatively active nodes. For SM-CA problem, we design
a greedy algorithm that yields a bicriteria $O(\ln n)$-approximation when
$\eta=n$, where $n$ is the number of nodes in the network. For both SM-CA
problem with $\eta<n$ and IM-CA problem, we prove strong inapproximability
results. Despite the hardness results, we propose two efficient heuristic
algorithms for SM-CA and IM-CA respectively based on the reverse reachable set
approach. Experimental results on different real-world social networks show
that our algorithms significantly outperform baseline algorithms.


title:
Learning the Problem-Optimum Map: Analysis and Application to Global
  Optimization in Robotics

abstract:
  This paper describes a data-driven framework for approximate global
optimization in which precomputed solutions to a sample of problems are
retrieved and adapted during online use to solve novel problems. This approach
has promise for real-time applications in robotics, since it can produce
near-globally optimal solutions orders of magnitude faster than standard
methods. This paper establishes theoretical conditions on how many and where
samples are needed over the space of problems to achieve a given approximation
quality. The framework is applied to solve globally optimal collision-free
inverse kinematics (IK) problems, wherein large solution databases are used to
produce near-optimal solutions in sub-millisecond time on a standard PC.


title: The arithmetic geometry of resonant Rossby wave triads

abstract:
  Linear wave solutions to the Charney-Hasegawa-Mima partial differential
equation with periodic boundary conditions have two physical interpretations:
Rossby (atmospheric) waves, and drift (plasma) waves in a tokamak. These waves
display resonance in triads. In the case of infinite Rossby deformation radius,
the set of resonant triads may be described as the set of integer solutions to
a particular homogeneous Diophantine equation, or as the set of rational points
on a projective surface. We give a rational parametrization of the smooth
points on this surface, answering the question: What are all resonant triads?
We also give a fiberwise description, yielding a procedure to answer the
question: For fixed $r \in \mathbb{Q}$, what are all wavevectors $(x,y)$ that
resonate with a wavevector $(a,b)$ with $a/b = r$?

categories: math.NT math-ph math.AG math.MP physics.flu-dyn


title:
Tracking Slowly Moving Clairvoyant: Optimal Dynamic Regret of Online
  Learning with True and Noisy Gradient

abstract:
  This work focuses on dynamic regret of online convex optimization that
compares the performance of online learning to a clairvoyant who knows the
sequence of loss functions in advance and hence selects the minimizer of the
loss function at each step. By assuming that the clairvoyant moves slowly
(i.e., the minimizers change slowly), we present several improved
variation-based upper bounds of the dynamic regret under the true and noisy
gradient feedback, which are {\it optimal} in light of the presented lower
bounds. The key to our analysis is to explore a regularity metric that measures
the temporal changes in the clairvoyant's minimizers, to which we refer as {\it
path variation}. Firstly, we present a general lower bound in terms of the path
variation, and then show that under full information or gradient feedback we
are able to achieve an optimal dynamic regret. Secondly, we present a lower
bound with noisy gradient feedback and then show that we can achieve optimal
dynamic regrets under a stochastic gradient feedback and two-point bandit
feedback. Moreover, for a sequence of smooth loss functions that admit a small
variation in the gradients, our dynamic regret under the two-point bandit
feedback matches what is achieved with full information.


title:
Alternating optimization method based on nonnegative matrix
  factorizations for deep neural networks

abstract:
  The backpropagation algorithm for calculating gradients has been widely used
in computation of weights for deep neural networks (DNNs). This method requires
derivatives of objective functions and has some difficulties finding
appropriate parameters such as learning rate. In this paper, we propose a novel
approach for computing weight matrices of fully-connected DNNs by using two
types of semi-nonnegative matrix factorizations (semi-NMFs). In this method,
optimization processes are performed by calculating weight matrices
alternately, and backpropagation (BP) is not used. We also present a method to
calculate stacked autoencoder using a NMF. The output results of the
autoencoder are used as pre-training data for DNNs. The experimental results
show that our method using three types of NMFs attains similar error rates to
the conventional DNNs with BP.


title:
The WISE Detection of an Infrared Echo in Tidal Disruption Event
  ASASSN-14li

abstract:
  We report the detection of a significant infrared variability of the nearest
tidal disruption event (TDE) ASASSN-14li using Wide-field Infrared Survey
Explorer} and newly released Near-Earth Object WISE Reactivation} data. In
comparison with the quiescent state, the infrared flux is brightened by 0.12
and 0.16 magnitude in the W1 ($3.4\mu$m) and W2 ($4.6\mu$m) bands at 36 days
after the optical discovery (or $\sim110$ days after the peak disruption date).
The flux excess is still detectable $\sim170$ more days later. Assuming that
the flare-like infrared emission is from the dust around the black hole, its
blackbody temperature is estimated to be $\sim2.1\times10^3$~K, slightly higher
than the dust sublimation temperature, indicating that the dust is likely
located close to the dust sublimation radius. The equilibrium between the
heating and radiation of the dust claims a bolometric luminosity of
$\sim10^{43}-10^{45}$~\lum, comparable with the observed peak luminosity. This
result has for the first time confirmed the detection of infrared emission from
the dust echoes of TDEs.


title:
Effective Hamiltonian based Monte Carlo for the BCS to BEC crossover in
  the attractive Hubbard model

abstract:
  We present an effective Hamiltonian based real-space approach for studying
the weak-coupling Bardeen-Cooper-Schrieffer (BCS) to the strong-coupling
Bose-Einstein condensate (BEC) crossover in the two-dimensional attractive
Hubbard model at finite temperatures. We introduce and justify an effective
classical Hamiltonian to describe the thermal fluctuations of the relevant
auxiliary fields. Our results for $T_c$ and phase diagrams compare very well
with those obtained from more sophisticated and {\it cpu}-intensive numerical
methods. We demonstrate that the method works in the presence of disorder and
is useful for a real-space description of the effect of disorder on
superconductivity. From a combined analysis of the superconducting order
parameter, the distribution of auxiliary fields and the quasiparticle density
of states, we identify the regions of metallic, insulating, superconducting and
pseudogapped behavior. Our finding of the importance of phase fluctuations for
the pseudogap behavior is consistent with the conclusions drawn from recent
experiments on NbN superconductors. The method can be generalized to study
superconductors with non-trivial order parameter symmetries by identifying the
relevant auxiliary variables.


title:
Growth and characterization of CaFe$_{1-x}$Co$_x$AsF single crystals by
  CaAs flux method

abstract:
  Millimeter sized single crystals of CaFe$_{1-x}$Co$_x$AsF were grown using a
self-flux method. It is found that high-quality single crystals can be grown
from three approaches with different initial raw materials. The chemical
compositions and crystal structure were characterized carefully. The c-axis
lattice constant is suppressed by the Co substitution. Superconductivity with
the critical transition $T_c$ as high as 21 K was confirmed by both the
resistivity and magnetic susceptibility measurements in the sample with $x$ =
0.12. Moreover, it is found that $T_c$ can be enhanced for about 1 K under the
very small hydrostatic pressure of 0.22 GPa, which is more quickly than that
reported in the polycrystalline samples. Our results is a promotion for the
physical investigations of 1111 phase iron-pnictide superconductors.


title:
On a gradient maximum principle for some quasilinear parabolic equations
  on convex domains

abstract:
  We establish a spatial gradient maximum principle for classical solutions to
the initial and Neumann boundary value problem of some quasilinear parabolic
equations on smooth convex domains.


title: Abnormal Subspace Sparse PCA for Anomaly Detection and Interpretation

abstract:
  The main shortage of principle component analysis (PCA) based anomaly
detection models is their interpretability. In this paper, our goal is to
propose an interpretable PCA-based model for anomaly detection and
interpretation. The propose ASPCA model constructs principal components with
sparse and orthogonal loading vectors to represent the abnormal subspace, and
uses them to interpret detected anomalies. Our experiments on a synthetic
dataset and two real world datasets showed that the proposed ASPCA models
achieved comparable detection accuracies as the PCA model, and can provide
interpretations for individual anomalies.


title:
Engineering of many-body Majorana states in a topological
  insulator/s-wave superconductor heterostructure

abstract:
  We study a vortex chain in a thin film of a topological insulator with
proximity-induced superconductivity---a promising platform to realize Majorana
zero modes (MZMs)---by modeling it as a two-leg Majorana ladder. While each
pair of MZMs hybridizes through vortex tunneling, we hereby show that MZMs can
be stabilized on the ends of the ladder with the presence of tilted external
magnetic field and four-Majorana interaction. Furthermore, a fruitful phase
diagram is obtained by controlling the direction of magnetic field and the
thickness of the sample. We reveal many-body Majorana states and
interaction-induced topological phase transitions and also identify
trivial-superconducting and commensurate/incommensurate charge-density-wave
states in the phase diagram.


title:
Revisiting constraints on small scale perturbations from big-bang
  nucleosynthesis

abstract:
  We revisit the constraints on the small scale density perturbations
($10^4\,\mathrm{Mpc}^{-1}\lesssim k \lesssim10^5\,\mathrm{Mpc}^{-1}$) from the
modification of the freeze-out value of the neutron-proton ratio at big-bang
nucleosynthesis era. Around the freeze-out temperature $T\sim
0.5\,\mathrm{MeV}$, the universe can be divided into several local patches
which have different temperatures since any perturbation which enters the
horizon after the neutrino decoupling has not diffused yet. Taking account of
this situation, we calculate the freeze-out value in detail. We find that the
small scale perturbations decrease the n-p ratio in contrast to previous works.
With use of the latest observed $^4$He abundance, we obtain the constraint on
the power spectrum of the curvature perturbations as
$\Delta^2_\mathcal{R}\lesssim 0.018$ on $10^4\,\mathrm{Mpc}^{-1}\lesssim k
\lesssim 10^5\,\mathrm{Mpc}^{-1}$.


title: Influence of Ni doping on critical parameters of PdTe superconductor

abstract:
  We report the effect of Ni doping on superconductivity of PdTe. The
superconducting parameters like critical temperature (Tc), upper critical field
(Hc2) and normalized specific-heat jump are reported for Ni doped Pd1-xNixTe.
The samples of series Pd1-xNixTe with nominal compositions x=0, 0.01, 0.05,
0.07, 0.1, 0.15, 0.2, 0.3 and 1.0 are synthesized via vacuum shield solid state
reaction route. All the studied samples of Pd1-xNixTe series are crystallized
in hexagonal crystal structure as refined by Rietveld method to space group
P63/mmc. Both the electrical resistivity and magnetic measurements revealed
that Tc decreases with increase of Ni concentration in Pd1-xNixTe. The
magneto-transport measurements suggest that flux is better pinned for 20% Ni
doped PdTe as compared to other compositions of Pd1-xNixTe. The effect and
contribution of Ni 3d electron to electronic structure and density of states
near Fermi level in Pd1-xNixTe are also studied using first-principle
calculations within spin polarized local density approximation. The overlap of
bands at Fermi level for NiTe is larger as compared to PdTe. Also the density
of states just below Fermi level (in conduction band) drops much lower for PdTe
than as for NiTe. Summarily, Ni doping in Pd1-xNixTe superconductor suppresses
superconductivity moderately and also Ni is of non magnetic character in these
compounds.


title: Do spikes persist in a quantum treatment of spacetime singularities?

abstract:
  The classical approach to spacetime singularities leads to a simplified
dynamics in which spatial derivatives become unimportant compared to time
derivatives, and thus each spatial point essentially becomes uncoupled from its
neighbors. This uncoupled dynamics leads to sharp features (called "spikes") as
follows: particular spatial points follow an exceptional dynamical path that
differs from that of their neighbors, with the consequence that, in the
neighborhood of these exceptional points, the spatial profile becomes ever more
sharp. Spikes are consequences of the BKL-type oscillatory evolution towards
generic singularities of spacetime. Do spikes persist when the spacetime
dynamics is treated using quantum mechanics? To address this question, we treat
a Hamiltonian system that describes the dynamics of the approach to the
singularity and consider how to quantize that system. We argue that this
particular system is best treated using an affine quantization approach (rather
than the more familiar methods of canonical quantization) and we set up the
formalism needed for this treatment. Our investigation, based on this affine
approach, shows the nonexistence of quantum spikes.


title:
$L^p$ boundedness of non-homogeneous Littlewood-Paley
  $g^*_{\lambda,\mu}$-function with non-doubling measures

abstract:
  It is well-known that the $L^p$ boundedness and weak $(1,1)$ estiamte
$(\lambda>2)$ of the classical Littlewood-Paley $g_{\lambda}^{*}$-function was
first studied by Stein, and the weak $(p,p)$ $(p>1)$ estimate was later given
by Fefferman for $\lambda=2/p$. In this paper, we investigated the $L^p(\mu)$
boundedness of the non-homogeneous Littlewood-Paley
$g_{\lambda,\mu}^{*}$-function with non-convolution type kernels and a power
bounded measure $\mu$: $$ g_{\lambda,\mu}^*(f)(x) = \bigg(\iint_{{\mathbb
R}^{n+1}_{+}} \Big(\frac{t}{t + |x - y|}\Big)^{m \lambda} |\theta_t^\mu f(y)|^2
\frac{d\mu(y) dt}{t^{m+1}}\bigg)^{1/2},\ x \in {\mathbb R}^n,\ \lambda > 1, $$
where $\theta_t^\mu f(y) = \int_{{\mathbb R}^n} s_t(y,z) f(z) d\mu(z)$, and
$s_t$ is a non-convolution type kernel. Based on a big piece prior boundedness,
we first gave a sufficient condition for the $L^p(\mu)$ boundedness of
$g_{\lambda,\mu}^*$. This was done by means of the non-homogeneous good lambda
method. Then, using the methods of dyadic analysis, we demonstrated a big piece
global $Tb$ theorem. Finally, we obtaind a sufficient and necessary condition
for $L^p(\mu)$ boundedness of $g_{\lambda,\mu}^*$-function. It is worth noting
that our testing conditions are weak $(1,1)$ type with respect to measures.


title: Higher-order theories from the minimal length

abstract:
  We show that the introduction of a minimal length in the context of
non-commutative spacetime gives rise (after some considerations) to
higher-order theories. We then explicitly demonstrate how these
higher-derivative theories appear as a generalization of the standard
electromagnetism and general relativity by applying a consistent procedure that
modifies the original Maxwell and Einstein-Hilbert actions. In order to set a
bound on the minimal length, we compare the deviations from the inverse-square
law with the potentials obtained in the higher-order theories and discuss the
validity of the results. The introduction of a quantum bound for the minimal
length parameter $\sqrt{\beta}$ in the higher-order QED allows us to lower the
actual limits on the parameters of higher-derivative gravity by almost half of
their order of magnitude.


title: Efficient Construction of Probabilistic Tree Embeddings

abstract:
  In this paper we describe an algorithm that embeds a graph metric $(V,d_G)$
on an undirected weighted graph $G=(V,E)$ into a distribution of tree metrics
$(T,D_T)$ such that for every pair $u,v\in V$, $d_G(u,v)\leq d_T(u,v)$ and
${\bf{E}}_{T}[d_T(u,v)]\leq O(\log n)\cdot d_G(u,v)$. Such embeddings have
proved highly useful in designing fast approximation algorithms, as many hard
problems on graphs are easy to solve on tree instances. For a graph with $n$
vertices and $m$ edges, our algorithm runs in $O(m\log n)$ time with high
probability, which improves the previous upper bound of $O(m\log^3 n)$ shown by
Mendel et al.\,in 2009.
  The key component of our algorithm is a new approximate single-source
shortest-path algorithm, which implements the priority queue with a new data
structure, the "bucket-tree structure". The algorithm has three properties: it
only requires linear time in the number of edges in the input graph; the
computed distances have a distance preserving property; and when computing the
shortest-paths to the $k$-nearest vertices from the source, it only requires to
visit these vertices and their edge lists. These properties are essential to
guarantee the correctness and the stated time bound.
  Using this shortest-path algorithm, we show how to generate an intermediate
structure, the approximate dominance sequences of the input graph, in $O(m \log
n)$ time, and further propose a simple yet efficient algorithm to converted
this sequence to a tree embedding in $O(n\log n)$ time, both with high
probability. Combining the three subroutines gives the stated time bound of the
algorithm.
  Then we show that this efficient construction can facilitate some
applications. We proved that FRT trees (the generated tree embedding) are
Ramsey partitions with asymptotically tight bound, so the construction of a
series of distance oracles can be accelerated.


title: Fast and Accurate Performance Analysis of LTE Radio Access Networks

abstract:
  An increasing amount of analytics is performed on data that is procured in a
real-time fashion to make real-time decisions. Such tasks include simple
reporting on streams to sophisticated model building. However, the practicality
of such analyses are impeded in several domains because they are faced with a
fundamental trade-off between data collection latency and analysis accuracy.
  In this paper, we study this trade-off in the context of a specific domain,
Cellular Radio Access Networks (RAN). Our choice of this domain is influenced
by its commonalities with several other domains that produce real-time data,
our access to a large live dataset, and their real-time nature and
dimensionality which makes it a natural fit for a popular analysis technique,
machine learning (ML). We find that the latency accuracy trade-off can be
resolved using two broad, general techniques: intelligent data grouping and
task formulations that leverage domain characteristics. Based on this, we
present CellScope, a system that addresses this challenge by applying a domain
specific formulation and application of Multi-task Learning (MTL) to RAN
performance analysis. It achieves this goal using three techniques: feature
engineering to transform raw data into effective features, a PCA inspired
similarity metric to group data from geographically nearby base stations
sharing performance commonalities, and a hybrid online-offline model for
efficient model updates. Our evaluation of CellScope shows that its accuracy
improvements over direct application of ML range from 2.5x to 4.4x while
reducing the model update overhead by up to 4.8x. We have also used CellScope
to analyze a live LTE consisting of over 2 million subscribers for a period of
over 10 months, where it uncovered several problems and insights, some of them
previously unknown.


title: Triple Point Topological Metals

abstract:
  Topologically protected fermionic quasiparticles appear in metals, where band
degeneracies occur at the Fermi level, dictated by the band structure topology.
While in some metals these quasiparticles are direct analogues of elementary
fermionic particles of the relativistic quantum field theory, other metals can
have symmetries that give rise to quasiparticles, fundamentally different from
those known in high-energy physics. Here we report on a new type of topological
quasiparticles -- triple point fermions -- realized in metals with symmorphic
crystal structure, which host crossings of three bands in the vicinity of the
Fermi level protected by point group symmetries. We find two topologically
different types of triple point fermions, both distinct from any other
topological quasiparticles reported to date. We provide examples of existing
materials that host triple point fermions of both types, and discuss a variety
of physical phenomena associated with these quasiparticles, such as the
occurrence of topological surface Fermi arcs, transport anomalies and
topological Lifshitz transitions.


title: Wavelet Scattering Regression of Quantum Chemical Energies

abstract:
  We introduce multiscale invariant dictionaries to estimate quantum chemical
energies of organic molecules, from training databases. Molecular energies are
invariant to isometric atomic displacements, and are Lipschitz continuous to
molecular deformations. Similarly to density functional theory (DFT), the
molecule is represented by an electronic density function. A multiscale
invariant dictionary is calculated with wavelet scattering invariants. It
cascades a first wavelet transform which separates scales, with a second
wavelet transform which computes interactions across scales. Sparse scattering
regressions give state of the art results over two databases of organic planar
molecules. On these databases, the regression error is of the order of the
error produced by DFT codes, but at a fraction of the computational cost.

categories: math.CA physics.chem-ph quant-ph stat.ML


title: Joint Learning of Sentence Embeddings for Relevance and Entailment

abstract:
  We consider the problem of Recognizing Textual Entailment within an
Information Retrieval context, where we must simultaneously determine the
relevancy as well as degree of entailment for individual pieces of evidence to
determine a yes/no answer to a binary natural language question.
  We compare several variants of neural networks for sentence embeddings in a
setting of decision-making based on evidence of varying relevance. We propose a
basic model to integrate evidence for entailment, show that joint training of
the sentence embeddings to model relevance and entailment is feasible even with
no explicit per-evidence supervision, and show the importance of evaluating
strong baselines. We also demonstrate the benefit of carrying over text
comprehension model trained on an unrelated task for our small datasets.
  Our research is motivated primarily by a new open dataset we introduce,
consisting of binary questions and news-based evidence snippets. We also apply
the proposed relevance-entailment model on a similar task of ranking
multiple-choice test answers, evaluating it on a preliminary dataset of school
test questions as well as the standard MCTest dataset, where we improve the
neural model state-of-art.


title: On the quantum spin Hall gap of monolayer 1T'-WTe2

abstract:
  Quantum spin Hall (QSH) materials are two-dimensional systems exhibiting
insulating bulk and helical edge states simultaneously. A QSH insulator
processes topologically non-trivial edge states protected by time-reversal
symmetry, so that electrons can propagate unscattered. Realization of such
topological phases enables promising applications in spintronics,
dissipationless transport and quantum computations. Presently, realization of
such QSH-based devices are limited to complicated heterostructures. Monolayer
1T'-WTe2 was predicted to be semimetallic QSH materials, though with a negative
band gap. The quasi-particle spectrum obtained using hybrid functional approach
shows directly that the quantum spin Hall gap is positive for monolayer
1T'-WTe2. Optical measurement shows a systematic increase in the interband
relaxation time with decreasing number of layers, whereas transport measurement
reveals Schottcky barrier in ultrathin samples, which is absent for thicker
samples. These three independent pieces of evidence indicate that monolayer
1T'-WTe2 is likely a truly 2-dimensional quantum spin Hall insulator.


title: Solve-Select-Scale: A Three Step Process For Sparse Signal Estimation

abstract:
  In the theory of compressed sensing (CS), the sparsity $\|x\|_0$ of the
unknown signal $\mathbf{x} \in \mathcal{R}^n$ is of prime importance and the
focus of reconstruction algorithms has mainly been either $\|x\|_0$ or its
convex relaxation (via $\|x\|_1$). However, it is typically unknown in practice
and has remained a challenge when nothing about the size of the support is
known. As pointed recently, $\|x\|_0$ might not be the best metric to minimize
directly, both due to its inherent complexity as well as its noise performance.
Recently a novel stable measure of sparsity $s(\mathbf{x}) :=
\|\mathbf{x}\|_1^2/\|\mathbf{x}\|_2^2$ has been investigated by Lopes
\cite{Lopes2012}, which is a sharp lower bound on $\|\mathbf{x}\|_0$. The
estimation procedure for this measure uses only a small number of linear
measurements, does not rely on any sparsity assumptions, and requires very
little computation. The usage of the quantity $s(\mathbf{x})$ in sparse signal
estimation problems has not received much importance yet. We develop the idea
of incorporating $s(\mathbf{x})$ into the signal estimation framework. We also
provide a three step algorithm to solve problems of the form $\mathbf{Ax=b}$
with no additional assumptions on the original signal $\mathbf{x}$.


title: Diffusion of Rb atoms in paraffin - coated resonant vapor cells

abstract:
  We present the results of a study of the diffusion of Rb atoms in paraffin -
coated resonant vapor cells. We have modeled the Rb diffusion both in the cell
and in the coating, assuming that the main loss of Rb atoms is due to the
physical absorption of the atoms by the glass substrate. It is demonstrated
that the equilibrium atomic density in the cell is a monotonic function of the
thickness of the paraffin coating: the density increases with an increase in
the thickness of the coating. The diffusion coefficient for rubidium in
paraffin thin films has been determined to be equal to 4,7*10^-7 cm^2/s. The
results of the experiment might be useful for a better understanding of the
details involved in the processes of the interaction of alkali atoms with a
paraffin coating.


title:
Critical endline of the finite temperature phase transition for 2+1
  flavor QCD around the SU(3)-flavor symmetric point

abstract:
  We investigate the critical endline of the finite temperature phase
transition of QCD around the SU(3)-flavor symmetric point at zero chemical
potential. We employ the renormalization-group improved Iwasaki gauge action
and non-perturbatively $O(a)$-improved Wilson-clover fermion action. The
critical endline is determined by using the intersection point of kurtosis,
employing the multi-parameter, multi-ensemble reweighting method to calculate
observables off the SU(3)-symmetric point, at the temporal size $N_{\rm T}$=6
and lattice spacing as low as $a \approx 0.19$ fm. We confirm that the slope of
the critical endline takes the value of $-2$, and find that the second
derivative is positive, at the SU(3)-flavor symmetric point on the Columbia
plot parametrized with the strange quark mass $m_s$ and degenerated up-down
quark mass $m_{\rm l}$.


title:
Black hole central engine for ultra-long gamma-ray burst 111209A and its
  associated supernova 2011kl

abstract:
  Recently, the first association between an ultra-long gamma-ray burst (GRB)
and a supernova is reported, i.e., GRB 111209A/SN 2011kl, which enables us to
investigate the physics of central engines or even progenitors for ultra-long
GRBs. In this paper, we inspect the broad-band data of GRB 111209A/SN 2011kl.
The late-time X-ray lightcurve exhibits a GRB 121027A-like fall-back bump,
suggesting a black hole central engine. We thus propose a collapsar model with
fall-back accretion for GRB 111209A/SN 2011kl. The required model parameters,
such as the total mass and radius of the progenitor star, suggest that the
progenitor of GRB 111209A is more likely a Wolf-Rayet star instead of blue
supergiant, and the central engine of this ultra-long burst is a black hole.
The implications of our results is discussed.


title: Optimization of Graph Based Codes for Belief Propagation Decoding

abstract:
  A low-density parity-check (LDPC) code is a linear block code described by a
sparse parity-check matrix, which can be efficiently represented by a bipartite
Tanner graph. The standard iterative decoding algorithm, known as belief
propagation, passes messages along the edges of this Tanner graph. Density
evolution is an efficient method to analyze the performance of the belief
propagation decoding algorithm for a particular LDPC code ensemble, enabling
the determination of a decoding threshold. The basic problem addressed in this
work is how to optimize the Tanner graph so that the decoding threshold is as
large as possible. We introduce a new code optimization technique which
involves the search space range which can be thought of as minimizing
randomness in differential evolution or limiting the search range in exhaustive
search. This technique is applied to the design of good irregular LDPC codes
and multiedge type LDPC codes.


title: Forman curvature for directed networks

abstract:
  A goal in network science is the geometrical characterization of complex
networks. In this direction, we (arXiv:1603.00386; J. Stat. Mech. (2016)
P063206) have recently introduced the Forman's discretization of Ricci
curvature to the realm of undirected networks. Investigation of Forman
curvature in diverse model and real-world undirected networks revealed that
this measure captures several aspects of the organization of complex undirected
networks. However, many important real-world networks are inherently directed
in nature, and the Forman curvature for undirected networks is unsuitable for
analysis of such directed networks. Hence, we here extend the Forman curvature
for undirected networks to the case of directed networks. The simple
mathematical formula for the Forman curvature in directed networks elegantly
incorporates node weights, edge weights and edge direction. By applying the
Forman curvature for directed networks to a variety of model and real-world
directed networks, we show that the measure can be used to characterize the
structure of complex directed networks. Furthermore, our results also hold in
real directed networks which are weighted or spatial in nature. These results
in combination with our previous results suggest that the Forman curvature can
be readily employed to study the organization of both directed and undirected
complex networks.


title:
On the problem of non-zero word error rates for fixed-rate error
  correction codes in continuous variable quantum key distribution

abstract:
  The maximum operational range of continuous variable quantum key distribution
protocols has shown to be improved by employing high-efficiency forward error
correction codes. Typically, the secret key rate model for such protocols is
modified to account for the non-zero word error rate of such codes. In this
paper, we demonstrate that this model is incorrect: Firstly, we show by example
that fixed-rate error correction codes, as currently defined, can exhibit
efficiencies greater than unity. Secondly, we show that using this secret key
model combined with greater than unity efficiency codes, implies that it is
possible to achieve a positive secret key over an entanglement breaking channel
- an impossible scenario. We then consider the secret key model from a
post-selection perspective, and examine the implications for key rate if we
constrain the forward error correction codes to operate at low word error
rates.


title: A Joint Optimization Technique for Multi-Edge Type LDPC Codes

abstract:
  This paper considers the optimization of multi-edge type low-density
parity-check (METLDPC) codes to maximize the decoding threshold. We propose an
algorithm to jointly optimize the node degree distribution and the multi-edge
structure of MET-LDPC codes for given values of the maximum number of
edge-types and maximum node degrees. This joint optimization is particularly
important for MET-LDPC codes as it is not clear a priori which structures will
be good. Using several examples, we demonstrate that the MET-LDPC codes
designed by the proposed joint optimization algorithm exhibit improved decoding
thresholds compared to previously reported MET-LDPC codes.


title:
New Density Evolution Approximation for LDPC and Multi-Edge Type LDPC
  Codes

abstract:
  This paper considers density evolution for lowdensity parity-check (LDPC) and
multi-edge type low-density parity-check (MET-LDPC) codes over the binary input
additive white Gaussian noise channel. We first analyze three singleparameter
Gaussian approximations for density evolution and discuss their accuracy under
several conditions, namely at low rates, with punctured and degree-one variable
nodes. We observe that the assumption of symmetric Gaussian distribution for
the density-evolution messages is not accurate in the early decoding
iterations, particularly at low rates and with punctured variable nodes. Thus
single-parameter Gaussian approximation methods produce very poor results in
these cases. Based on these observations, we then introduce a new density
evolution approximation algorithm for LDPC and MET-LDPC codes. Our method is a
combination of full density evolution and a single-parameter Gaussian
approximation, where we assume a symmetric Gaussian distribution only after
density-evolution messages closely follow a symmetric Gaussian distribution.
Our method significantly improves the accuracy of the code threshold
estimation. Additionally, the proposed method significantly reduces the
computational time of evaluating the code threshold compared to full density
evolution thereby making it more suitable for code design.


title: Light-cone gauge superstring field theory in linear dilaton background

abstract:
  The Feynman amplitudes of light-cone gauge superstring field theory suffer
from various divergences. In order to regularize them, we study the theory in
linear dilaton background $\Phi =-iQX^1$ with the number of spacetime
dimensions fixed. We show that the theory with the Feynman
$i\varepsilon\,(\varepsilon>0)$ and $Q^{2}>10$ yields finite results.


title: Walking from 750 GeV to 950 GeV in the Technipion Zoo

abstract:
  If the 750 GeV diphoton excess is identified with the color-singlet
isosinglet-technipion, $P^0$ (750), in the one-family walking technicolor, as
in our previous paper, then there should exist another color-singlet
technipion, isotriplet one, $P^{\pm,3}$, definitely predicted at around 950 GeV
independently of the dynamical details. The $P^{\pm,3}(950)$ are produced at
the LHC via vector boson and photon fusion processes, predominantly decaying to
$W \gamma$, and $\gamma\gamma$, respectively. Those walking technicolor signals
can be explored at the Run 2, or 3, which would further open a way to a
plethora of yet other (colored) technipions.


abstract:
  We study the massive ODE/IM correspondence for modified $B_2^{(1)}$ affine
Toda field equation. Based on the $\psi$-system for the solutions of the
associated linear problem, we obtain the Bethe ansatz equations. We also
discuss the T-Q relations, the T-system and the Y-system, which are shown to be
related to those of the $A_3/{\bf Z}_2$ integrable system. We consider the case
that the solution of the linear problem has a monodromy around the origin,
which imposes nontrivial boundary conditions for the T-/Y-system. The
high-temperature limit of the T- and Y-system and their monodromy dependence
are studied numerically.


title: Electronic specific heat in BaFe$_{2-x}$Ni$_x$As$_2$

abstract:
  We have systematically studied the low-temperature specific heat of the
BaFe$_{2-x}$Ni$_x$As$_2$ single crystals covering the whole superconducting
dome. Using the nonsuperconducting heavily overdoped x = 0.3 sample as a
reference for the phonon contribution to the specific heat, we find that the
normal-state electronic specific heats in the superconducting samples may have
a nonlinear temperature dependence, which challenges previous results in the
electron-doped Ba-122 iron-based superconductors. A model based on the presence
of ferromagnetic spin fluctuations may explain the data between x = 0.1 and x =
0.15, suggesting the important role of Fermi-surface topology in understanding
the normal-state electronic states.


title: Particle Production in Ekpyrotic Scenarios

abstract:
  We consider Parker particle production in the Ekpyrotic scenario (in
particular in the New Ekpyrotic model) and show that the density of particles
produced by the end of the phase of Ekpyrotic contraction is sufficient to lead
to a hot state of matter after the bounce. Hence, no separate reheating
mechanism is necessary.


title: Wilkie's conjecture for restricted elementary functions

abstract:
  We consider the structure ${\mathbb R}^{\mathrm{RE}}$ obtained from
$({\mathbb R},<,+,\cdot)$ by adjoining the restricted exponential and sine
functions. We prove Wilkie's conjecture for sets definable in this structure:
the number of rational points of height $H$ in the transcendental part of any
definable set is bounded by a polynomial in $\log H$. We also prove two refined
conjectures due to Pila concerning the density of algebraic points from a fixed
number field, or with a fixed algebraic degree, for ${\mathbb
R}^{\mathrm{RE}}$-definable sets.


title:
A Critical Examination of RESCAL for Completion of Knowledge Bases with
  Transitive Relations

abstract:
  Link prediction in large knowledge graphs has received a lot of attention
recently because of its importance for inferring missing relations and for
completing and improving noisily extracted knowledge graphs. Over the years a
number of machine learning researchers have presented various models for
predicting the presence of missing relations in a knowledge base. Although all
the previous methods are presented with empirical results that show high
performance on select datasets, there is almost no previous work on
understanding the connection between properties of a knowledge base and the
performance of a model. In this paper we analyze the RESCAL method and prove
that it can not encode asymmetric transitive relations in knowledge bases.


title:
Simultaneous Identification of Coefficient and Initial State for
  One-Dimensional Heat Equation from Boundary Control and Measurement

abstract:
  In this paper, we consider simultaneous reconstruction of the diffusion
coefficient and initial state for a one-dimensional heat equation through
boundary control and measurement. The boundary measurement is known to make the
system exactly observable, and both coefficient and initial state are shown to
be identifiable by this measurement. By a Dirichlet series representation for
observation, we can transform the problem into an inverse process of
reconstruction of the spectrum and coefficients for Dirichlet series in terms
of observation. This happens to be the reconstruction of spectral data for an
exponential sequence with measurement error. This enables us to develop an
algorithm based on the matrix pencil method in signal analysis. An error
analysis is made for the proposed method. The numerical simulations are
presented to verify the proposed algorithm.


title: An almost ideal coordination mechanism for unrelated machine scheduling

abstract:
  Coordination mechanisms aim to mitigate the impact of selfishness when
scheduling jobs to different machines. Such a mechanism defines a scheduling
policy within each machine and naturally induces a game among the selfish job
owners. The desirable properties of a coordination mechanism includes
simplicity in its definition and efficiency of the outcomes of the induced
game. We present a broad class of coordination mechanisms for unrelated machine
scheduling that are simple to define and we identify one of its members
(mechanism \Dcoord) that is superior to all known mechanisms. \Dcoord\ induces
potential games with logarithmic price of anarchy and only constant price of
stability. Both bounds are almost optimal.


title: Magnetic susceptibility of the QCD vacuum in a nonlocal SU(3) PNJL model

abstract:
  The magnetic susceptibility of the QCD vacuum is analyzed in the framework of
a nonlocal SU(3) Polyakov-Nambu-Jona-Lasinio model. Considering two different
model parametrizations, we estimate the values of the $u$ and $s$-quark tensor
coefficients and magnetic susceptibilities and then we extend the analysis to
finite temperature systems. Our numerical results are compared to those
obtained in other theoretical approaches and in lattice QCD calculations.


title: Modified Bekenstein-Hawking system in $f(R)$ gravity

abstract:
  The present work deals with four alternative formulation of Bekenstein system
on event horizon in $f(R)$ gravity. While thermodynamical laws holds in
universe bounded by apparent horizon, these laws break down on event horizon.
With alternative formulation of thermodynamical parameters (temperature and
entropy), thermodynamical laws hold on event horizon in Einstein Gravity. With
this motivation, we extend the idea of generalised Hawking temperature and
modified Bekenstein entropy in homogeneous and isotropic model of universe on
event horizon and examine whether thermodynamical laws hold in f(R) gravity.
Specifically, we examine and compare validity of generalised second law of
thermodynamics (GSLT) and thermodynamical equilibrium (TE) in four alternative
modified Bekenstein scenarios. As Dark energy is a possible dominant candidate
for matter in the univerese and Holographic Dark Energy (HDE) can give
effective description of f(R) gravity, so matter in the universe is taken as in
the form interacting HDE. In order to understand the complicated expressions,
finally the above laws are examined from graphical representation using three
Planck data sets and it is found that generalised/modified Hawking temperature
has a crucial role in making perfect thermodynamical system.


title:
An easy proof of the general Neron desingularization in dimension $\leq
  1$

abstract:
  In this paper we give an easy proof of the general Neron desingularization in
the frame of regular morphism between Artinian local rings and Noetherian local
rings of dimension one.


title:
Fourier Transform Ultrasound Spectroscopy For the Determination of Wave
  Propagation Parameters

abstract:
  The reported results for ultrasonic wave attenuation constant ({\alpha}) in
pure water show noticeable inconsistency in magnitude. A "Propagating-Wave"
model analysis of the most popular pulse-echo technique indicates that this is
a consequence of the inherent wave propagation characteristics in a bounded
medium. In the present work Fourier Transform Ultrasound Spectroscopy (FTUS) is
adopted to determine ultrasonic wave propagation parameters, the wave number
(k) and attenuation constant ({\alpha}) at 1MHz frequency in tri-distilled
water at room temperature (25oC). Pulse-echo signals obtained under same
experimental conditions regarding the exciting input signal and reflecting
boundary wall of the water container for various lengths of water columns are
captured. The Fast Fourier Transform (FFT) components of the echo signals are
taken to compute k, {\alpha} and r, the reflection constant at the boundary,
using Oak Ridge and Oxford method. The results are compared with existing
literature values.


title: Typical Performance of Approximation Algorithms for NP-hard Problems

abstract:
  Typical performance of approximation algorithms is studied for randomized
minimum vertex cover problems. A wide class of random graph ensembles
characterized by an arbitrary degree distribution is discussed with some
theoretical frameworks. Here three approximation algorithms are examined; the
linear-programming relaxation, the loopy-belief propagation, and the
leaf-removal algorithm. The former two algorithms are analyzed using the
statistical-mechanical technique while the average-case analysis of the last
one is studied by the generating function method. These algorithms have a
threshold in the typical performance with increasing the average degree of the
random graph, below which they find true optimal solutions with high
probability. Our study reveals that there exist only three cases determined by
the order of the typical-performance thresholds. We provide some conditions for
classifying the graph ensembles and demonstrate explicitly examples for the
difference in the threshold.


title: Extremal rays and nefness of tangent bundles

abstract:
  In view of Mori theory, rational homogenous manifolds satisfy a recursive
condition: every elementary contraction is a rational homogeneous fibration and
the image of any elementary contraction also satisfies the same property. In
this paper, we show that a smooth Fano $n$-fold with the same condition and
Picard number greater than $n-6$ is either a rational homogeneous manifold or
the product of $n-7$ copies of $\mathbb{P}^1$ and a Fano $7$-fold $X_0$
constructed by G. Ottaviani. We also clarify that $X_0$ has non-nef tangent
bundle and in particular is not rational homogeneous.


title: Nonlinear waves in the terrestrial quasi-parallel foreshock

abstract:
  We study the applicability of the derivative nonlinear Schr\"{o}dinger (DNLS)
equation, for the evolution of high frequency nonlinear waves, observed at the
foreshock region of the terrestrial quasi-parallel bow shock. The use of a
pseudo-potential is elucidated and, in particular, the importance of canonical
representation in the correct interpretation of solutions in this formulation
is discussed. Numerical solutions of the DNLS equation are then compared
directly with the wave forms observed by Cluster spacecraft. Non harmonic slow
variations are filtered out by applying the empirical mode decomposition. We
find large amplitude nonlinear wave trains at frequencies above the proton
cyclotron frequency, followed in time by nearly harmonic low amplitude
fluctuations. The approximate phase speed of these nonlinear waves, indicated
by the parameters of numerical solutions, is of the order of the local
Alfv\'{e}n speed.


title:
High-Performance Computing for Scheduling Decision Support: A Parallel
  Depth-First Search Heuristic

abstract:
  Many academic disciplines - including information systems, computer science,
and operations management - face scheduling problems as important decision
making tasks. Since many scheduling problems are NP-hard in the strong sense,
there is a need for developing solution heuristics. For scheduling problems
with setup times on unrelated parallel machines, there is limited research on
solution methods and to the best of our knowledge, parallel computer
architectures have not yet been taken advantage of. We address this gap by
proposing and implementing a new solution heuristic and by testing different
parallelization strategies. In our computational experiments, we show that our
heuristic calculates near-optimal solutions even for large instances and that
computing time can be reduced substantially by our parallelization approach.


title:
Empirical probability model of the cold plasma environment in Jovian
  inner magnetosphere

abstract:
  A new empirical, analytical model of cold plasma (< 10 keV) in the Jovian
inner magnetosphere is constructed. Plasmas in this energy range impact surface
charging. A new feature of this model is predicting each plasma parameter for a
specified probability (percentile). The new model was produced as follows. We
start from a reference model for each plasma parameter, which was scaled to fit
the data of Galileo plasma spectrometer. The scaled model was then represented
as a function of radial distance, magnetic local time, and magnetic latitude,
presumably describing the mean states. Then, the deviation of the observed
values from the model were attribute to the variability in the environment,
which was accounted for by the percentile at a given location.The input
parameters for this model are the spacecraft position and the percentile. The
model is inteded to be used for the JUICE mission analysis.


title: Pole shape optimization using a Tabu search scheme

abstract:
  The pole shape optimization of an electromagnet typical of an MRI type
application is investigated. We compare the use of different parameterizations
of the pole shape and compare the convergence of the optimizations using a
discrete variable step length Tabu Search scheme.


title:
Spin-polarization in the vicinity of quantum point contact with
  spin-orbit interaction

abstract:
  We have developed a novel technique for detection of spin polarization with a
quantum dot weakly coupled to the objective device. The disturbance to the
object in this technique is very small since the detection is performed through
sampling of single electrons in the object with very slow rate. We have applied
the method to a quantum point contact (QPC) under a spin-orbit interaction. A
high degree of spin polarization in the vicinity of the QPC was detected when
the conductance stayed on a plateau at a half of the unit conductance quantum
($G_{\rm q}/2\equiv e^2/h$), and also on another plateau at $2e^2/h$. On the
half-quantum plateau, the degree of polarization $P$ decreased with the bias
source-drain voltage of the QPC while $P$ increased on the single-quantum
plateau, manifesting that different mechanisms of polarization were working on
these plateaus. Very long spin relaxation times in the detector quantum dot
probably due to dynamical nuclear spin polarization were observed. Anomalous
decrease of $P$ around zero-bias was observed at a Kondo-like resonance peak.


title: GMD-Based Hybrid Precoding For Millimeter-Wave Massive MIMO Systems

abstract:
  Hybrid precoding can significantly reduce the number of required radio
frequency (RF) chains and relieve the huge energy consumption in mmWave massive
MIMO systems, thus attracting much interests from academic and industry.
However, most existing hybrid precoding schemes are based on singular value
decomposition (SVD). Due to the very different sub-channel signal-to-noise
ratios (SNRs) after SVD, complicated bit allocations is usually required to
match the sub-channel SNRs. To solve this problem, we propose a geometric mean
decomposition (GMD)-based hybrid precoding scheme to avoid the complicated bit
allocation. Its basic idea is to seek a pair of analog and digital precoding
matrices that are sufficiently close to the optimal unconstrained GMD precoding
matrix. Specifically, we design the analog (digital) precoding matrix while
keeping the digital (analog) precoding matrix fixed. Further, the principle of
basis pursuit is utilized in the design of analog precoding matrix, while we
obtain the digital precoding matrix by projecting the GMD operation on the
digital precoding matrix. Simulation results verify that the proposed GMD-based
hybird precoding scheme outperforms conventional SVD-based hybrid precoding
schemes and achieves much better bit error rate (BER) performance with low
complexity.


title: Architecting Data Quality for Continuous Student Behaviour Management

abstract:
  Data capture and use is vital for the continuous improvement of both student
learning and behavior management. Previous studies on data use in the education
sector have highlighted a number of problems associated with data quality and
its subsequent use. These include the accuracy, consistency, completeness, and
timeliness of data. Engagement issues with data have centred on the
interpretation and application of the knowledge that data can provide. No study
to date has investigated the link between IS design and the production of
quality data that captures student progression and outcomes in either the
learning or behavior management environments. This study reports on the design,
development, implementation and evaluation of a novel artefact facilitating
quality data for one classroom based education service: pastoral care. This
study, using design science research methods, shows that Information Systems
Design is a major barrier to teacher adoption and use of classroom based
Information Systems.


title:
Suitable weak solutions to the 3D Navier-Stokes equations are
  constructed with the Voigt Approximation

abstract:
  In this paper we consider the Navier-Stokes equations supplemented with
either the Dirichlet or vorticity-based Navier boundary conditions. We prove
that weak solutions obtained as limits of solutions to the Navier-Stokes-Voigt
model satisfy the local energy inequality. Moreover, in the periodic setting we
prove that if the parameters are chosen in an appropriate way, then we can
construct suitable weak solutions trough a Fourier-Galerkin finite-dimensional
approximation in the space variables.


title:
Manifestation of extrinsic spin Hall effect in superconducting
  structures: Non-dissipative magnetoelectric effects

abstract:
  We present a comprehensive quasiclassical approach for studying transport
properties of superconducting diffusive hybrid structures in the presence of
extrinsic spin-orbit coupling. We derive a generalized Usadel equation and
boundary conditions that in the normal state reduce to the drift-diffusion
theory governing the spin-Hall effect in inversion symmetric materials. These
equations predict the non-dissipative spin-galvanic effect, that is the
generation of supercurrents by a spin-splitting field, and its inverse -- the
creation of magnetic moment by a supercurrent. These effects can be seen as
counterparts of the spin-Hall, anomalous Hall and their inverse effects in the
superconducting state. Our theory opens numerous possibilities for using
superconducting structures in magnetoelectronics.


title: Multiple list colouring of planar graphs

abstract:
  This paper proves that for each positive integer $m$, there is a planar graph
$G$ which is not $(4m+\lfloor \frac{2m-1}{9}\rfloor,m)$-choosable. Then we pose
some conjectures concerning multiple list colouring of planar graphs.


title: On Avoidance Learning with Partial Observability

abstract:
  We study a framework where agents have to avoid aversive signals. The agents
are given only partial information, in the form of features that are
projections of task states. Additionally, the agents have to cope with
non-determinism, defined as unpredictability on the way that actions are
executed. The goal of each agent is to define its behavior based on
feature-action pairs that reliably avoid aversive signals. We study a learning
algorithm, called A-learning, that exhibits fixpoint convergence, where the
belief of the allowed feature-action pairs eventually becomes fixed. A-learning
is parameter-free and easy to implement.


title:
Les Houches 2015: Physics at TeV Colliders Standard Model Working Group
  Report

abstract:
  This Report summarizes the proceedings of the 2015 Les Houches workshop on
Physics at TeV Colliders. Session 1 dealt with (I) new developments relevant
for high precision Standard Model calculations, (II) the new PDF4LHC parton
distributions, (III) issues in the theoretical description of the production of
Standard Model Higgs bosons and how to relate experimental measurements, (IV) a
host of phenomenological studies essential for comparing LHC data from Run I
with theoretical predictions and projections for future measurements in Run II,
and (V) new developments in Monte Carlo event generators.


title:
Overcoming the language barrier in mobile user interface design: A case
  study on a mobile health app

abstract:
  This research report proposes a structured solution to address the need for
awareness of cultural and language in user design. It will include evaluated
research on established methods that already exist. Discussed ideas about how
to address this situation include: what others have found to take into
consideration when using design principles to develop an interface, detailed
troubles and critical issues that have been previously identified and also ways
that have been found already to overcome such issues. This will also involve
designing a prototype application catering to resolving these issues.
Overcoming the language barrier plays an important role in the process of
implementing a user design interface that will satisfy users. This issue must
be researched and examined to identify the issues and concerns associated in
order to provide a solution in an ethical manner.


title: Ehrhart polynomials of 3-dimensional simple integral convex polytopes

abstract:
  We give an explicit formula on the Ehrhart polynomial of a 3-dimensional
simple integral convex polytope by using toric geometry.


title:
A Process Model for Crowdsourcing: Insights from the Literature on
  Implementation

abstract:
  The purpose of the current study is to systematically review the
crowdsourcing literature, extract the activities which have been cited, and
synthesise these activities into a general process model. For this to happen,
we reviewed the related literature on crowdsourcing methods as well as relevant
case studies and extracted the activities which they referred to as part of
crowdsourcing projects. The systematic review of the related literature and an
in-depth analysis of the steps in those papers were followed by a synthesis of
the extracted activities resulting in an eleven-phase process model. This
process model covers all of the activities suggested by the literature. This
paper then briefly discusses activities in each phase and concludes with a
number of implications for both academics and practitioners.


title: The Case for Dynamic Key Distribution for PKI-Based VANETs

abstract:
  Vehicular Ad hoc Networks (VANETs) are becoming a reality where secure
communication is a prerequisite. Public key infrastructure (PKI) can be used to
secure VANETs where an onboard tamper proof device (TPD) stores a number of
encryption keys which are renewed upon visiting a certificate authority (CA).
We previously proposed a dynamic key distribution protocol for PKI-based VANETs
[1] to reduce the role of the TPD. A vehicle dynamically requests a key from
its nearest road side unit. This request is propagated through network
infrastructure to reach a CA cloud and a key is securely returned. A proposed
key revocation mechanism reduced the number of messages needed for revocation
through Certificate Revocation List (CRL) distribution. In this paper,
performance evaluation and security of the proposed dynamic key distribution is
investigated analytically and through network simulation. Furthermore,
extensive analysis is performed to demonstrate how the proposed protocol can
dynamically support efficient and cost-reduced key distribution. Analysis and
performance evaluation results clearly make the case for dynamic key
distribution for PKI-based VANETS.