title: Guided Policy Search as Approximate Mirror Descent

abstract:
  Guided policy search algorithms can be used to optimize complex nonlinear
policies, such as deep neural networks, without directly computing policy
gradients in the high-dimensional parameter space. Instead, these methods use
supervised learning to train the policy to mimic a "teacher" algorithm, such as
a trajectory optimizer or a trajectory-centric reinforcement learning method.
Guided policy search methods provide asymptotic local convergence guarantees by
construction, but it is not clear how much the policy improves within a small,
finite number of iterations. We show that guided policy search algorithms can
be interpreted as an approximate variant of mirror descent, where the
projection onto the constraint manifold is not exact. We derive a new guided
policy search algorithm that is simpler and provides appealing improvement and
convergence guarantees in simplified convex and linear settings, and show that
in the more general nonlinear setting, the error in the projection step can be
bounded. We provide empirical results on several simulated robotic navigation
and manipulation tasks that show that our method is stable and achieves similar
or better performance when compared to prior guided policy search methods, with
a simpler formulation and fewer hyperparameters.


title: Picosecond all-optical switching of magnetic tunnel junctions

abstract:
  Control of magnetism without using magnetic fields enables large-scale
integration of spintronic devices for memory, computation and communication in
the beyond-CMOS era. Mechanisms including spin torque transfer, spin Hall
effect, and electric field or strain assisted switching have been implemented
to switch magnetization in various spintronic devices. Their operation speed,
however, is fundamentally limited by the spin precession time to be longer than
10-100 picoseconds. Overcoming such a speed constraint is critical for the
prospective development of spintronics. Here we report the demonstration of
picosecond all-optical switching of a magnetic tunnel junction (MTJ)- the
building block of spintronic logic and memory -only using single telecom-band,
infrared laser pulses. This first optically switchable MTJ uses ferrimagnetic
GdFeCo as the free layer, and its switching is directly readout by measuring
its tunneling magnetoresistance with a DR/R ratio of 0.6%. An instrument
limited switching repetition rate at MHz has been demonstrated, but the
fundamental limit should be higher than tens of GHz. This result represents an
important step toward integrated opto-spintronic devices that combines
spintronics and photonics technologies to enable ultrafast conversion between
fundamental information carriers of electron spins and photons.


title: Strain Effects on Oxygen Migration in Perovskites

abstract:
  Fast oxygen transport materials are necessary for a range of technologies,
including efficient and cost-effective solid oxide fuel cells, gas separation
membranes, oxygen sensors, chemical looping devices, and memristors. Strain is
often proposed as a method to enhance the performance of oxygen transport
materials, but the magnitude of its effect and its underlying mechanisms are
not well-understood, particularly in the widely-used perovskite-structured
oxygen conductors. This work reports on an ab initio prediction of strain
effects on migration energetics for nine perovskite systems of the form LaBO3,
where B = [Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Ga]. Biaxial strain, as might be
easily produced in epitaxial systems, is predicted to lead to approximately
linear changes in migration energy. We find that tensile biaxial strain reduces
the oxygen vacancy migration barrier across the systems studied by an average
of 66 meV per percent strain for a single selected hop, with a low of 36 and a
high of 89 meV decrease in migration barrier per percent strain across all
systems. The estimated range for the change in migration barrier within each
system is approximately 25 meV per percent strain when considering all hops.
These results suggest that strain can significantly impact transport in these
materials, e.g., a 2% tensile strain can increase the diffusion coefficient by
about three orders of magnitude at 300 K (one order of magnitude at 500 {\deg}C
or 773 K) for one of the most strain-responsive materials calculated here
(LaCrO3). We show that a simple elasticity model, which assumes only dilative
or compressive strain in a cubic environment and a fixed migration volume, can
qualitatively but not quantitatively model the strain dependence of the
migration energy, suggesting that factors not captured by continuum elasticity
play a significant role in the strain response.


title: Maximizing complementary quantities by projective measurements

abstract:
  In this work we study the so-called quantitative complementarity quantities.
We focus in the following physical situation: two qubits ($q_A$ and $q_B$) are
initially in a maximally entangled state. One of them ($q_B$) interacts with a
$N$-qubit system ($R$). After the interaction, projective measurements are
performed in each of the qubits of $R$, in a basis that is chosen after
independent optimization procedures: maximization of the visibility, the
concurrence and the predictability. For a specific maximization procedure, we
study in details how each of the complementary quantities behave, conditioned
on the intensity of the coupling between $q_B$ and the $N$ qubits. We show
that, if the coupling is sufficiently "strong", independent of the maximization
procedure, the concurrence tends to decay quickly. Interestingly enough, the
behavior of the concurrence in this model is similar to the entanglement
dynamics of a two qubit system subjected to a thermal reservoir, despite that
we consider finite $N$. However the visibility shows a different behavior: its
maximization is more efficient for stronger coupling constants. Moreover, we
investigate how the distinguishability, or the information stored in different
parts of the system, is distributed for different couplings.


title:
Synchronised firing patterns in a random network of adaptive exponential
  integrate-and-fire

abstract:
  We have studied neuronal synchronisation in a random network of adaptive
exponential integrate-and-fire neurons. We study how spiking or bursting
synchronous behaviour appears as a function of the coupling strength and the
probability of connections, by constructing parameter spaces that identify
these synchronous behaviours from measurements of the inter-spike interval and
the calculation of the order parameter. Moreover, we verify the robustness of
synchronisaton by applying an external perturbation to each neuron. The
simulations show that bursting synchronisation is more robust than spike
synchronisation.


title:
Rigorous numerical enclosures for positive solutions of Lane-Emden's
  equation with sub-square exponents

abstract:
  The purpose of this paper is to obtain rigorous numerical enclosures for
solutions of Lane-Emden's equation $-\Delta u=|u|^{p-1} u$ with homogeneous
Dirichlet boundary conditions. We prove the existence of a nondegenerate
solution $u$ nearby a numerically computed approximation $\hat{u}$ together
with an explicit error bound, i.e., a bound for the difference between $ u $
and $\hat{u}$. In particular, we focus on the sub-square case in which $1<p<2$
so that the derivative $p|u|^{p-1}$ of the nonlinearity $|u|^{p-1} u$ is not
Lipschitz continuous. In this case, it is problematic to apply the classical
Newton-Kantorovich theorem for obtaining the existence proof, and moreover
several difficulties arise in the procedures to obtain numerical integrations
rigorously. We design a method for enclosing the required integrations
explicitly, proving the existence of a desired solution based on a generalized
Newton-Kantorovich theorem. A numerical example is presented where an explicit
solution-enclosure is obtained for $ p=3/2 $ on the unit square domain
$\Omega=(0,1)^2$.


title:
Collapse of the $Gd^{3+}$ ESR fine structure throughout the coherent
  temperature of the Gd-doped Kondo Semiconductor $CeFe_{4}P_{12}$

abstract:
  Experiments on the $Gd^{3+}$ Electron Spin Resonance (ESR) in the filled
skutterudite $Ce_{1-x}Gd_{x}Fe_{4}P_{12}$ ($x \approx 0.001$), at temperatures
where the host resistivity manifests a smooth insulator-metal crossover,
provides evidence of the underlying Kondo physics associated with this system.
At low temperatures (below $T \approx K$), $Ce_{1-x}Gd_{x}Fe_{4}P_{12}$ behaves
as a Kondo-insulator with a relatively large hybridization gap, and the
$Gd^{3+}$ ESR spectra displays a fine structure with lorentzian line shape,
typical of insulating media. The electronic gap is attributed to the large
hybridization present in the coherent regime of a Kondo lattice, when Ce
4f-electrons cooperate with band properties at half-filling. Mean-field
calculations suggest that the electron-phonon interaction is fundamental at
explaining the strong 4f-electron hybridization in this filled skutterudite.
The resulting electronic structure is strongly temperature dependent, and at
about $T^{*} \approx 160 K$ the system undergoes an insulator-to-metal
transition induced by the withdrawal of 4f-electrons from the Fermi volume, the
system becoming metallic and non-magnetic. The $Gd^{3+}$ ESR fine structure
coalesces into a single dysonian resonance, as in metals. Still, our
simulations suggest that exchange-narrowing via the usual Korringa mechanism,
alone, is not capable of describing the thermal behavior of the ESR spectra in
the entire temperature region ($4.2$ - $300$ K). We propose that temperature
activated fluctuating-valence of the Ce ions is the missing ingredient that,
added to the usual exchange-narrowing mechanism, fully describes this unique
temperature dependence of the $Gd^{3+}$ ESR fine structure observed in
$Ce_{1-x}Gd_{x}Fe_{4}P_{12}$.


title:
Coherent structure extraction in turbulent channel flow using boundary
  adapted wavelets

abstract:
  We present a construction of isotropic boundary adapted wavelets, which are
orthogonal and yield a multi-resolution analysis. We analyze direct numerical
simulation data of turbulent channel flow computed at a friction Reynolds
number of 395, and investigate the role of coherent vorticity. Thresholding of
the vorticity wavelet coefficients allows to split the flow into two parts,
coherent and incoherent vorticity. The coherent vorticity is reconstructed from
their few intense wavelet coefficients. The statistics of the coherent part,
i.e., energy and enstrophy spectra, are close to the statistics of the total
flow, and moreover, the nonlinear energy budgets are very well preserved. The
remaining incoherent part, represented by the large majority of the weak
wavelet coefficients, corresponds to a structureless, i.e., noise-like,
background flow whose energy is equidistributed.


title: Finite Dimensional Representations of Leavitt Path Algebras

abstract:
  When $\Gamma$ is a row-finite di(rected )graph we classify all finite
dimensional modules of the Leavitt path algebra $L(\Gamma)$ via an explicit
Morita equivalence given by an effective combinatorial (reduction) algorithm on
the digraph $\Gamma$. The category of (unital) $L(\Gamma)$-modules is
equivalent to a subcategory of quiver representations of $\Gamma$. However the
category of finite dimensional representations of $L(\Gamma)$ is tame in
contrast to the finite dimensional quiver representations of $\Gamma$ which are
almost always wild.


title: Nuclear Physics Around the Unitarity Limit

abstract:
  We argue that many features of the structure of nuclei emerge from a strictly
perturbative expansion around the unitarity limit, where the two-nucleon S
waves have bound states at zero energy. In this limit, the gross features of
states in the nuclear chart are correlated to only one dimensionful parameter,
which is related to the breaking of scale invariance to a discrete scaling
symmetry and set by the triton binding energy. Observables are moved to their
physical values by small, perturbative corrections, much like in descriptions
of the fine structure of atomic spectra. We provide evidence in favor of the
conjecture that light, and possibly heavier, nuclei are bound weakly enough to
be insensitive to the details of the interactions but strongly enough to be
insensitive to the exact size of the two-nucleon system.


title: Normal State of the Metallic Hydrogen Sulfide

abstract:
  Generalized theory of the normal properties of the metal in the case of the
electron-phonon (EP) systems with not constant density of electronic states is
used to examine the normal state of the SH3 and SH2 phase of the hydrogen
sulfide at different pressures. The frequency dependence of the real and
imaginary part of the self-energy part (SP) of the electron Green's function,
the real and imaginary part of the complex renormalization of the electron
mass, the real and imaginary part of the complex renormalization of the
chemical potential, as well as the renormalized with the strong electron-phonon
interaction the electron density of states are calculated. The calculations are
performed for the stable orthorhombic IM-3M hydrogen sulfide SH3 structure at
three pressures P = 170 GPa, P = 180 GPa, P = 225 GPa and SH2 structure with
the symmetry I4/MMM (D4H-17) for the three values of pressure P = 150 GPa , P =
180 GPa, P = 225 GPa at the temperature of T = 200K. Key words: hydrogen
sulfide, electron-phonon system, the pressure, the electronic properties.


title: Imaging in random media with convex optimization

abstract:
  We study an inverse problem for the wave equation where localized wave
sources in random scattering media are to be determined from time resolved
measurements of the waves at an array of receivers. The sources are far from
the array, so the measurements are affected by cumulative scattering in the
medium, but they are not further than a transport mean free path, which is the
length scale characteristic of the onset of wave diffusion that prohibits
coherent imaging. The inversion is based on the Coherent Interferometric (CINT)
imaging method which mitigates the scattering effects by introducing an
appropriate smoothing operation in the image formation. This smoothing
stabilizes statistically the images, at the expense of their resolution. We
complement the CINT method with a convex ($l_1$) optimization in order to
improve the source localization and obtain quantitative estimates of the source
intensities. We analyze the method in a regime where scattering can be modeled
by large random wavefront distortions, and quantify the accuracy of the
inversion in terms of the spatial separation of individual sources or clusters
of sources. The theoretical predictions are demonstrated with numerical
simulations.


title: On harmonic Bloch-type mappings

abstract:
  Let $f$ be a complex-valued harmonic mapping defined in the unit disk
$\mathbb D$. We introduce the following notion: we say that $f$ is a Bloch-type
function if its Jacobian satisfies $$ \sup_{z\in\mathbb
D}(1-|z|^2)\sqrt{|J_f(z)|}<\infty. $$ This gives rise to a new class of
functions which generalizes and contains the well-known analytic Bloch space.
We give estimates for the schlicht radius, the growth and the coefficients of
functions in this class. We establish an analogue of the theorem which states
that an analytic $\varphi$ is Bloch if and only if there exists $c>0$ and a
univalent $\psi$ such that $\varphi = c \log \psi'$.


title:
Dynamics of water and solute transport in polymeric reverse osmosis
  membranes via molecular dynamics simulations

abstract:
  The Angstrom-scale transport characteristics of water and six different
solutes, methanol, ethanol, 2-propanol, urea, Na+, and Cl-, were studied for a
polyamide reverse osmosis (RO) membrane, FT-30, using non-equilibrium molecular
dynamics (NEMD) simulations. Results indicate that water transport increases
with an increasing fraction of connected percolated free volume, or
water-accessible open space, in the membrane polymer structure. This free
volume is enhanced by the dynamic structure of the membrane at the molecular
level as it swells when hydrated and vibrates due to molecular collisions
allowing a continuous path connecting the opposite membrane surfaces. The
tortuous paths available for transport of solutes result in Brownian motion of
solute molecules and hopping from pore to pore as they pass through the polymer
network structure of the membrane. The transport of alcohol solutes decreases
for solutes with larger Van der Waals volume, which corresponds to less
available percolated free volume, or solute-accessible space, within the
membrane polymer structure. However, the Van der Waals size of the dehydrated
solutes is generally not a good measure to predict solute transport or
rejection. Urea has reduced transport compared to ethanol, most likely due to
more complex chemistry, even though urea has a smaller Van der Waals volume
than ethanol. Na+ and Cl- experience the lowest transport, likely due to strong
ion-water and ion-ion electrostatic interactions.


title: New Evidence for (0,2) Target Space Duality

abstract:
  In the context of (0,2) gauged linear sigma models, we explore chains of
perturbatively dual heterotic string compactifications. The notion of target
space duality originates in non-geometric phases and can be used to generate
distinct GLSMs with shared geometric phases leading to apparently identical
target space theories. To date, this duality has largely been studied at the
level of counting states in the effective theories. We extend this analysis to
the effective potential and loci of enhanced symmetry in dual theories. By
engineering vector bundles with non-trivial constraints arising from
slope-stability (i.e. D-terms) and holomorphy (i.e. F-terms) the detailed
structure of the vacuum space of the dual theories can be explored. Our results
give new evidence that GLSM target space duality may provide important hints
towards a more complete understanding of (0,2) string dualities.


title: Lightweight Security Protocol for WiSense based Wireless Sensor Network

abstract:
  Wireless Sensor Networks have emerged as one of the leading technologies.
These networks are designed to monitor crucial environmental parameters of
humidity, temperature, wind speed, soil moisture content, UV index, sound, etc.
and then transfer the required information to the base station. However,
security remains the key challenge of such networks as critical data is being
transferred. Most sensor nodes currently deployed have constraints on memory
and processing power and hence operate without an efficient security protocol.
Hereby a protocol which is lightweight and is secure for wireless sensor
applications is proposed.


title:
Impulse-induced generation of stationary and moving discrete breathers
  in nonlinear oscillator networks

abstract:
  We study discrete breathers in prototypical nonlinear oscillator networks
subjected to non-harmonic zero-mean periodic excitations. We show how the
generation of stationary and moving discrete breathers are optimally controlled
by solely varying the impulse transmitted by the periodic excitations, while
keeping constant the excitation's amplitude and period. Our theoretical and
numerical results show that the enhancer effect of increasing values of the
excitation's impulse, in the sense of facilitating the generation of stationary
and moving breathers, is due to a correlative increase of the breather's action
and energy.


title:
Area bounds for minimal surfaces that pass through a prescribed point in
  a ball

abstract:
  Let $\Sigma$ be a $k$-dimensional minimal submanifold in the $n$-dimensional
unit ball $B^n$ which passes through a point $y \in B^n$ and satisfies
$\partial \Sigma \subset \partial B^n$. We show that the $k$-dimensional area
of $\Sigma$ is bounded from below by $|B^k| \, (1-|y|^2)^{\frac{k}{2}}$. This
settles a question left open by the work of Alexander and Osserman in 1973.


title: Strategic tradeoffs in competitor dynamics on adaptive networks

abstract:
  Recent empirical work highlights the heterogeneity of social competitions
such as political campaigns: proponents of some ideologies seek debate and
conversation, others create echo chambers. While symmetric and static network
structure is typically used as a substrate to study such competitor dynamics,
network structure can instead be interpreted as a signature of the competitor
strategies, yielding competition dynamics on adaptive networks. Here we
demonstrate that tradeoffs between aggressiveness and defensiveness (i.e.,
targeting adversaries vs. targeting like-minded individuals) creates
paradoxical behaviour such as non-transitive dynamics. And while there is an
optimal strategy in a two competitor system, three competitor systems have no
such solution; the introduction of extreme strategies can easily affect the
outcome of a competition, even if the extreme strategies have no chance of
winning. Not only are these results reminiscent of classic paradoxical results
from evolutionary game theory, but the structure of social networks created by
our model can be mapped to particular forms of payoff matrices. Consequently,
social structure can act as a measurable metric for social games which in turn
allows us to provide a game theoretical perspective on online political
debates.


title:
Neutrino, $\gamma$-ray and cosmic ray fluxes from the core of the
  closest radio galaxies

abstract:
  The closest radio galaxies; Centaurus A, M87 and NGC 1275, have been detected
from radio wavelengths to TeV $\gamma$-rays, and also studied as high-energy
neutrino and ultra-high-energy cosmic ray potential emitters. Their spectral
energy distributions show a double-peak feature, which is explained by
synchrotron self-Compton model. However, TeV $\gamma$-ray measured spectra
could suggest that very-high-energy $\gamma$-rays might have a hadronic origin.
We introduce a lepto-hadronic model to describe the broadband spectral energy
distribution; from radio to sub GeV photons as synchrotron self-Compton
emission and TeV $\gamma$-ray photons as neutral pion decay resulting from
p$\gamma$ interactions occurring close to the core. These photo-hadronic
interactions take place when Fermi-accelerated protons interact with the seed
photons around synchrotron self-Compton peaks. Obtaining a good description of
the TeV $\gamma$-ray fluxes, firstly, we compute neutrino fluxes and events
expected in IceCube detector and secondly, we estimate ultra-high-energy cosmic
ray fluxes and event rate expected in Telescope Array, Pierre Auger and HiRes
observatories. Within this scenario we show that the expected high-energy
neutrinos cannot explain the astrophysical flux observed by IceCube, and the
connection with ultra-high-energy cosmic rays observed by Auger experiment
around Centaurus A, might be possible only considering a heavy nuclei
composition in the observed events.


title:
Topology of representation spaces of surface groups in PSL(2,R) with
  assigned boundary monodromy and nonzero Euler number

abstract:
  In this paper we complete the topological description of the space of
representations of the fundamental group of a punctured surface in SL(2,R) with
prescribed behavior at the punctures and nonzero Euler number, following the
strategy employed by Hitchin in the unpunctured case and exploiting
Hitchin-Simpson correspondence between flat bundles and Higgs bundles in the
parabolic case. This extends previous results by Boden-Yokogawa and
Nasatyr-Steer. A relevant portion of the paper is intended to give an overview
of the subject.


title: Photon-initiated processes at high mass

abstract:
  We consider the influence of photon-initiated processes on high-mass particle
production. We discuss in detail the photon PDF at relatively high parton $x$,
relevant to such processes, and evaluate its uncertainties. In particular we
show that, as the dominant contribution to the input photon distribution is due
to coherent photon emission, at phenomenologically relevant scales the photon
PDF is already well determined in this region, with the corresponding
uncertainties under good control. We then demonstrate the implications of this
result for the example processes of high-mass lepton and $W$ boson pair
production at the LHC and FCC. While for the former process the
photon-initiated contribution is expected to be small, in the latter case we
find that it is potentially significant, in particular at larger masses.


title:
A kinetic transport-projection splitting algorithm for an hierarchy of
  moment closures of gas-kinetic equations

abstract:
  We review some geometrical properties of models of moment closures of
gas-kinetic equations, and consider a transport-projection splitting scheme for
construction of solutions of such closures. The scheme, formulated in terms of
a dual kinetic density, defines the kinetic density in successive superposition
of transport in $x$--direction and projection to a finite dimensional linear
space in a weighted $L^2$ space, in the kinetic variable $v.$ Given smooth
initial data, we show that the approximate solutions converge to a unique
classical solution of a system of moment closure PDEs.


title:
Inference of Unresolved Point Sources At High Galactic Latitudes Using
  Probabilistic Catalogs

abstract:
  Detection of point sources in images is a fundamental operation in
astrophysics, and is crucial for constraining population models of the
underlying point sources or characterizing the background emission. Standard
techniques fall short in the crowded-field limit, losing sensitivity to faint
sources and failing to track their covariance with close neighbors. We
construct a Bayesian framework to perform inference of faint or overlapping
point sources. The method involves probabilistic cataloging, where samples are
taken from the posterior probability distribution of catalogs consistent with
an observed photon count map. In order to validate our method we sample random
catalogs of the gamma-ray sky in the direction of the North Galactic Pole (NGP)
by binning the data in energy and Point Spread Function (PSF) classes. Using
three energy bins spanning $0.3 - 1$, $1 - 3$ and $3 - 10$ GeV, we identify
$270\substack{+30 \\ -10}$ point sources inside a $40^\circ \times 40^\circ$
region around the NGP above our point-source inclusion limit of $3 \times
10^{-11}$/cm$^2$/s/sr/GeV at the $1-3$ GeV energy bin. Modeling the flux
distribution as a power law, we infer the slope to be $-1.92\substack{+0.07 \\
-0.05}$ and estimate the contribution of point sources to the total emission as
$18\substack{+2 \\ -2}$\%. These uncertainties in the flux distribution are
fully marginalized over the number as well as the spatial and spectral
properties of the unresolved point sources. This marginalization allows a
robust test of whether the apparently isotropic emission in an image is due to
unresolved point sources or of truly diffuse origin.

categories: astro-ph.IM astro-ph.CO astro-ph.GA astro-ph.HE hep-ph


title: Dynamically Correcting a CNOT Gate for any Systematic Logical Error

abstract:
  We derive a set of composite pulse sequences that generates CNOT gates and
correct all systematic errors within the logical subspace to arbitrary order.
These sequences are applicable for any two-qubit interaction Hamiltonian, and
make no assumptions about the underlying noise mechanism except that it is
constant on the timescale of the operation. We do assume access to error-free
single-qubit gates, so single-qubit gate imperfections eventually limit the
achievable fidelity. However, since single-qubit gates generally have much
higher fidelities than two-qubit gates in practice, these pulse sequences offer
useful dynamical correction for a wide range of coupled qubit systems.


title:
Extinction law in the range 0.4-4.8 $\mu$m and the 8620 $\AA$ DIB
  towards the stellar cluster Westerlund 1

abstract:
  The young stellar cluster Westerlund 1 (Wd 1: $l$=339.6$^\circ$,
b=$-$0.4$^\circ$) is one of the most massive in the local Universe, but
accurate parameters are pending on better determination of its extinction and
distance. Based on our photometry and data collected from other sources, we
have derived a reddening law for the cluster line-of-sight representative of
the Galactic Plane (-5$^\circ<$b$<$+5$^\circ$) in the window 0.4-4.8 $\mu$m:
The power law exponent $\alpha$=2.13$\pm$0.08 is much steeper than those
published a decade ago (1.6-1.8) and our index $R_V$=2.50$\pm$0.04 also differs
from them, but in very good agreement with recent works based on deep surveys
in the inner Galaxy. As a consequence, the total extinction $A_{Ks}$=0.74$ \pm
$0.08 ($A_V$=11.40$ \pm$ 2.40) is substantially smaller than previous
results(0.91-1.13), part of which ($A_{Ks}$=0.63 or $A_V$=9.66) is from the
ISM. The extinction in front of the cluster spans a range of $\Delta
A_V\sim$8.7\,mag with a gradient increasing from SW to NE across the cluster
face, following the same general trend of warm dust distribution. The map of
the $J-Ks$ colour index also shows a trend of reddening in this direction. We
measured the equivalent width of the diffuse interstellar band at 8620 $\AA$
(the "GAIA DIB") for Wd 1 cluster members and derived the relation
$A_{Ks}$=0.612 $EW$ $-$ 0.191 $EW^2$. This extends the Munari et al. (2008)
relation, valid for $E_{B-V}$ $<$ 1, to the non-linear regime ($A_V$ $>$ 4).


title:
Honeycomb-lattice Heisenberg-Kitaev model in a magnetic field: Spin
  canting, metamagnetism, and vortex crystals

abstract:
  The Heisenberg-Kitaev model is a paradigmatic model to describe the magnetism
in honeycomb-lattice Mott insulators with strong spin-orbit coupling, such as
A$_2$IrO$_3$ (A = Na, Li) and $\alpha$-RuCl$_3$. Here we study in detail the
physics of the Heisenberg-Kitaev model in an external magnetic field. Using a
combination of Monte-Carlo simulations and spin-wave theory we map out the
classical phase diagram for different directions of the magnetic field. Broken
SU(2) spin symmetry renders the magnetization process rather complex, with
sequences of phases and metamagnetic transitions. In particular, we find
various large-unit-cell and multi-Q phases including a vortex-crystal phase for
a field in the [111] direction. We also discuss quantum corrections in the
high-field phase.


title:
A $\mathcal{M}\gtrsim3$ shock in `El Gordo' cluster and the origin of
  the radio relic

abstract:
  We present an X-ray and radio study of the famous `El Gordo', a massive and
distant ($z=0.87$) galaxy cluster. In the deep (340 ks) Chandra observation,
the cluster appears with an elongated and cometary morphology, a sign of its
current merging state. The GMRT radio observations at 610 MHz reveal the
presence of a radio halo which remarkably overlaps the X-ray cluster emission
and connects a couple of radio relics. We detect a strong shock
($\mathcal{M}\gtrsim3$) in the NW periphery of the cluster, co-spatially
located with the radio relic. This is the most distant ($z=0.87$) and one of
the strongest shock detected in a galaxy cluster. This work supports the
relic-shock connection and allows to investigate the origin of these radio
sources in a uncommon regime of $\mathcal{M}\gtrsim3$. For this particular case
we found that shock acceleration from the thermal pool is still a viable
possibility.


title:
Qubit Transport Model for Unitary Black Hole Evaporation without
  Firewalls

abstract:
  We give an explicit toy qubit transport model for transferring information
from the gravitational field of a black hole to the Hawking radiation by a
continuous unitary transformation of the outgoing radiation and the black hole
gravitational field. The model has no firewalls or other drama at the event
horizon, and it avoids a counterargument that has been raised for subsystem
transfer models as resolutions of the firewall paradox. Furthermore, it fits
the set of six physical constraints that Giddings has proposed for models of
black hole evaporation. It does utilize nonlocal qubits for the gravitational
field but assumes that the radiation interacts locally with these nonlocal
qubits, so in some sense the nonlocality is confined to the gravitational
sector. Although the qubit model is too crude to be quantitively correct for
the detailed spectrum of Hawking radiation, it fits qualitatively with what is
expected.


title:
Chiral heavy fermions in a two Higgs doublet model: 750 GeV resonance or
  not

abstract:
  We revisit models where a heavy chiral 4th generation doublet of fermions is
embedded in a class of two Higgs doublets models (2HDM) with a discrete $Z_2$
symmetry, which couples the "heavy" scalar doublet only to the 4th generation
fermions and the "light" one to the Standard Model (SM) fermions - the
so-called 4G2HDM introduced by us several years ago. We study the constraints
imposed on the 4G2HDM from direct searches of heavy fermions, from precision
electroweak data (PEWD) and from the measured production and decay signals of
the 125 GeV scalar, which in the 4G2HDM corresponds to the lightest CP-even
scalar h. We then show that the recently reported excess in the $\gamma\gamma$
spectrum around 750 GeV can be accommodated by the heavy CP-even scalar of the
4G2HDM, H, resulting in a unique choice of parameter space: negligible mixing
(sin\alpha ~ O(0.001)) between the two CP-even scalars h,H and heavy 4th
generation quark and lepton masses m_t',m_b' < 400 GeV and $m_{\nu'},m_{\tau'}$
> 900 GeV, respectively. Whether or not the 750 GeV \gamma \gamma resonance is
confirmed, interesting phenomenology emerges in q' - Higgs systems (q'=t',b'),
that can be searched for at the LHC. For example, the heavy scalar states of
the model, S=H,A,H^+, may have BR(S -> q'q') ~ O(1), giving rise to observable
q'q' signals on resonance, followed by the flavor changing q' decays t'->uh
(u=u,c) and/or b'->dh (d=d,s,b). This leads to distinct high jet-multiplicity
signatures, with or without charged leptons, of the form q'q' -> (nj + mb +
lW)_S (j and b being light and b-quark jets, respectively), with n+m+l =6-8 and
unique kinematic features. It is also shown that the 4G2HDM can easily
accommodate the interesting recent indications of a percent-level branching
ratio in the lepton-flavor-violating (LFV) decay $h \to \tau \mu$ of the 125
GeV Higgs, if confirmed.


title:
A Neural Network Gravitational Arc Finder based on the Mediatrix
  filamentation Method

abstract:
  Automated arc detection methods are needed to scan the ongoing and
next-generation wide-field imaging surveys, which are expected to contain
thousands of strong lensing systems. Arc finders are also required for a
quantitative comparison between predictions and observations of arc abundance.
Several algorithms have been proposed to this end, but machine learning methods
have remained as a relatively unexplored step in the arc finding process. In
this work we introduce a new arc finder based on pattern recognition, which
uses a set of morphological measurements derived from the Mediatrix
Filamentation Method as entries to an Artificial Neural Network (ANN). We show
a full example of the application of the arc finder, first training and
validating the ANN on simulated arcs and then applying the code on four Hubble
Space Telescope (HST) images of strong lensing systems. The simulated arcs use
simple prescriptions for the lens and the source, while mimicking HST
observational conditions. We also consider a sample of objects from HST images
with no arcs in the training of the ANN classification. We use the training and
validation process to determine a suitable set of ANN configurations, including
the combination of inputs from the Mediatrix method, so as to maximize the
completeness while keeping the false positives low. In the simulations the
method was able to achieve a completeness of about 90% with respect to the arcs
that are input to the ANN after a preselection. However, this completeness
drops to $\sim$ 70% on the HST images. The false detections are of the order of
3% of the objects detected in these images. The combination of Mediatrix
measurements with an ANN is a promising tool for the pattern recognition phase
of arc finding. More realistic simulations and a larger set of real systems are
needed for a better training and assessment of the efficiency of the method.


title: Entanglement Continuous Unitary Transformations

abstract:
  Continuous unitary transformations are a powerful tool to extract valuable
information out of quantum many-body Hamiltonians, in which the so-called flow
equation transforms the Hamiltonian to a diagonal or block-diagonal form in
second quantization. Yet, one of their main challenges is how to approximate
the infinitely-many coupled differential equations that are produced throughout
this flow. Here we show that tensor networks offer a natural and
non-perturbative truncation scheme in terms of entanglement. The corresponding
scheme is called "entanglement-CUT" or eCUT. It can be used to extract the
low-energy physics of quantum many-body Hamiltonians, including quasiparticle
energy gaps. We provide the general idea behind eCUT and explain its
implementation for finite 1d systems using the formalism of matrix product
operators. We also present proof-of-principle results for the spin-1/2 1d
quantum Ising model and the 3-state quantum Potts model in a transverse field.
Entanglement-CUTs can also be generalized to higher dimensions and to the
thermodynamic limit.


title: Optimal and Secure Measurement Protocols for Quantum Sensor Networks

abstract:
  Studies of quantum metrology have shown that the use of many-body entangled
states can lead to an enhancement in sensitivity when compared to product
states. In this paper, we quantify the metrological advantage of entanglement
in a setting where the quantity to be measured is a linear function of
parameters coupled to each qubit individually. We first generalize the
Heisenberg limit to the measurement of non-local observables in a quantum
network, deriving a bound based on the multi-parameter quantum Fisher
information. We then propose a protocol that can make use of GHZ states or
spin-squeezed states, and show that in the case of GHZ states the procedure is
optimal, i.e., it saturates our bound.


title:
Tunable spin-orbit coupling and symmetry-protected edge states in
  graphene/WS$_2$

abstract:
  We demonstrate clear weak anti-localization (WAL) effect arising from induced
Rashba spin-orbit coupling (SOC) in WS$_2$-covered single-layer and bilayer
graphene devices. Contrary to the uncovered region of a shared single-layer
graphene flake, WAL in WS$_2$-covered graphene occurs over a wide range of
carrier densities on both electron and hole sides. At high carrier densities,
we estimate the Rashba SOC relaxation rate to be $\sim 0.2 \rm{ps}^{-1}$ and
show that it can be tuned by transverse electric fields. In addition to the
Rashba SOC, we also predict the existence of a `valley-Zeeman' SOC from
first-principles calculations. The interplay between these two SOC's can open a
non-topological but interesting gap in graphene; in particular, zigzag
boundaries host four sub-gap edge states protected by time-reversal and
crystalline symmetries. The graphene/WS$_2$ system provides a possible platform
for these novel edge states.


title:
Context Matters: Refining Object Detection in Video with Recurrent
  Neural Networks

abstract:
  Given the vast amounts of video available online, and recent breakthroughs in
object detection with static images, object detection in video offers a
promising new frontier. However, motion blur and compression artifacts cause
substantial frame-level variability, even in videos that appear smooth to the
eye. Additionally, video datasets tend to have sparsely annotated frames. We
present a new framework for improving object detection in videos that captures
temporal context and encourages consistency of predictions. First, we train a
pseudo-labeler, that is, a domain-adapted convolutional neural network for
object detection. The pseudo-labeler is first trained individually on the
subset of labeled frames, and then subsequently applied to all frames. Then we
train a recurrent neural network that takes as input sequences of
pseudo-labeled frames and optimizes an objective that encourages both accuracy
on the target frame and consistency across consecutive frames. The approach
incorporates strong supervision of target frames, weak-supervision on context
frames, and regularization via a smoothness penalty. Our approach achieves mean
Average Precision (mAP) of 68.73, an improvement of 7.1 over the strongest
image-based baselines for the Youtube-Video Objects dataset. Our experiments
demonstrate that neighboring frames can provide valuable information, even
absent labels.


title:
Electrified magnetic catalysis in three-dimensional topological
  insulators

abstract:
  The gap equations for the surface quasiparticle propagators in a slab of
three-dimensional topological insulator in external electric and magnetic
fields perpendicular to the slab surfaces are analyzed and solved. A different
type of magnetic catalysis is revealed with the dynamical generation of both
Haldane and Dirac gaps. Its characteristic feature manifests itself in the
crucial role that the electric field plays in dynamical symmetry breaking and
the generation of a Dirac gap in the slab. It is argued that, for a
sufficiently large external electric field, the ground state of the system is a
phase with a homogeneous surface charge density.


title:
Enhanced association and dissociation of heteronuclear Feshbach
  molecules in a microgravity environment

abstract:
  We study the association and dissociation dynamics of weakly bound
heteronuclear Feshbach molecules using transverse RF-fields for expected
parameters accessible through the microgravity environment of NASA's Cold Atom
Laboratory (CAL) aboard the International Space Station, including temperatures
at or below nK and atomic densities as low as $10^8$/cm$^3$. We show that under
such conditions, thermal and loss effects can be greatly suppressed resulting
in high efficiency in both association and dissociation of Feshbach molecules
with mean size exceeding 10$^4a_0$, and allowing for the coherence in
atom-molecule transitions to be clearly observable. Our theoretical model for
heteronuclear mixtures includes thermal, loss, and density effects in a simple
and conceptually clear manner. We derive the temperature, density and
scattering length regimes of $^{41}$K-$^{87}$Rb that allow optimal
association/dissociation efficiency with minimal heating and loss to guide
future experiments with ultracold atomic gases in space.


title: Phone-sized whispering-gallery microresonator sensing system

abstract:
  We develop a compact whispering-gallery-mode (WGM) sensing system by
integrating multiple components, including a tunable laser, a temperature
controller, a function generator, an oscilloscope, a photodiode detector, and a
testing computer, into a phone-sized embedded system. We demonstrate a thermal
sensing experiment by using this portable system. Such a system successfully
eliminates bulky measurement equipment required for characterizing optical
resonators and will open up new avenues for practical sensing applications by
using ultra-high Q WGM resonators.


title:
Many-Body Localization in System with a Completely Delocalized
  Single-Particle Spectrum

abstract:
  Many-body localization (MBL) in a one-dimensional Fermi Hubbard model with
random on-site interactions is studied. While for this model all
single-particle states are trivially delocalized, it is shown that for
sufficiently strong disordered interactions the model is many-body localized.
It is therefore argued that MBL does not necessary rely on localization of the
single-particle spectrum. This model provides a convenient platform to study
pure MBL phenomenology, since Anderson localization in this model does not
exist. By examining various forms of the interaction term a dramatic effect of
symmetries on charge transport is demonstrated. A possible realization in a
cold atom experiments is proposed.


title:
Assessing the differences between numerical methods, CAD evaluations and
  real experiments for the assessement of reach envelopes of the human body

abstract:
  Numerical models and computer-aided modeling software are tools commonly used
to assess the accessibility of an environment, based on static human body
dimensions. In this paper, the limits of validity of these approaches are
assessed by comparing the reach envelopes obtained by these methods to those
obtained experimentally. First, the accessibility areas of forty adult
subjects, which may correspond to the distance of reachability of products,
were evaluated by performing an accessibility task comprising 168 reach points.
Second, anthropometric characteristics of participants were recorded and used
to perform the reach assessment by a numerical method, and then by a CAD-based
analysis, where the reach was predicted using the software's maximum
reach-envelope generation. In spite of the simple nature of the presented
design problem (two-dimensional), the results show important differences
between the three methods. The study of the number of reached points shows that
the CAD-based assessment provides more accurate results than the numerical
model. Nevertheless, the shapes envelopes comparison indicates that the maximum
reach envelopes obtained with the CAD analysis are not always consistent with
those obtained experimentally, closely linked to the hand location. Results
indicate that the CAD model used to obtain maximum reaches gave predictions
that underestimate the reach ability.


title: Supernova Remnant Evolution: from explosion to dissipation

abstract:
  Here is considered the full evolution of a spherical supernova remnant. We
start by calculating the early time ejecta dominated stage and continue through
the different phases of interaction with the circumstellar medium, and end with
the dissipation and merger phase. The physical connection between the phases
reveals new results. One is that the blast wave radius during the adiabatic
phase is significantly smaller than it would be, if one does notaccount for the
blast wave interaction with the ejecta.


title:
Prediction of the vibroacoustic response of a structure-liner-fluid
  system based on a patch transfer function approach and direct experimental
  subsystem characterisation

abstract:
  The vibro-acoustic response of a structure-liner-fluid system is predicted by
application of a patch impedance coupling methodology. In contrast to existing
numerical approaches, impedance matrices of structure and liner are determined
by a direct experimental approach, avoiding the requirement of material
parameters. Emphasis is placed on poroelastic lining materials. The method
accounts for surface input and transfer terms and for cross and cross-transfer
terms through the specimen. A single test-rig characterisation procedure for
layered poroelastic media is proposed. The specimen is considered as a single
component -- no separation of layers is necessary. Problem specific boundary
conditions for skeleton and fluid, which may cause non-reciprocal cross terms,
are dealt with by the procedure. Methods of measurement for the assessment of
impedance matrices are presented and their accuracy and limitations are
discussed. An air gap correction method for surface impedance measurements is
presented.


title:
Stochastic dynamics of three competing clones: Conditions and times for
  invasion, coexistence and fixation

abstract:
  In large clonal populations, several clones generally compete which results
in complex evolutionary and ecological dynamics: experiments show successive
selective sweeps of favorable mutations as well as long-term coexistence of
multiple clonal strains. The mechanisms underlying either coexistence or
fixation of several competing strains have rarely been studied altogether.
Conditions for coexistence have mostly been studied by population and community
ecology, while rates of invasion and fixation have mostly been studied by
population genetics. In order to provide a global understanding of the
complexity of the dynamics observed in large clonal populations, we develop a
stochastic model where three clones compete. Competitive interactions can be
intransitive and we suppose that strains enter the population via mutations or
rare immigrations. We first describe all possible final states of the
population, including stable coexistence of two or three strains, or the
fixation of a single strain. Second, we give estimate of the invasion and
fixation times of a favorable mutant (or immigrant) entering the population in
a single copy. We show that invasion and fixation can be slower or faster when
considering complex competitive interactions. Third, we explore the parameter
space assuming prior distributions of reproduction, death and competitive rates
and we estimate the likelihood of the possible dynamics. We show that when
mutations can affect competitive interactions, even slightly, stable
coexistence is likely. We discuss our results in the context of the
evolutionary dynamics of large clonal populations.


title:
Entropy as a function of magnetization for a 2D spin-ice model
  exhibiting a Kasteleyn transition

abstract:
  We present a combined analytical and numerical study of the entropy as a
function of magnetization for an orientable 2D spin-ice model that exhibits a
Kasteleyn transition. The model that we use is related to the well known
six-vertex model but, as we show, our representation of it is more convenient
for constructing approximate expressions for the entropy at fixed
magnetization. We also discuss directions for further work, including the
possibility of deforming our model into one exhibiting a quantum Kasteleyn
transition.


title: Slopes of modular forms and the ghost conjecture (unabridged version)

abstract:
  We formulate a conjecture on slopes of overconvergent p-adic cuspforms of any
p-adic weight in the Gamma_0(N)-regular case. This conjecture unifies a
conjecture of Buzzard on classical slopes and more recent conjectures on slopes
"at the boundary of weight space".


title:
New orbits of irregular satellites designed for the predictions of
  stellar occultations up to 2020, based on thousands of new observations

abstract:
  Gomes-J\'unior et al. (2015) published 3613 positions for the 8 largest
irregular satellites of Jupiter and 1787 positions for the largest irregular
satellite of Saturn, Phoebe. These observations were made between 1995 and 2014
and have an estimated error of about 60 to 80 mas. Based on this set of
positions, we derived new orbits for the eight largest irregular satellites of
Jupiter: Himalia, Elara, Pasiphae, Carme, Lysithea, Sinope, Ananke and Leda.
For Phoebe we updated the ephemeris from Desmars et al. (2013) using 75% more
positions than the previous one. Due to their orbital characteristics, it is
common belief that the irregular satellites were captured by the giant planets
in the early Solar System, but there is no consensus for a single model
explaining where they were formed. Size, shape, albedo and composition would
help to trace back their true origin, but these physical parameters are yet
poorly known for irregular satellites. The observation of stellar occultations
would allow for the determination of such parameters. Indeed Jupiter will cross
the galactic plane in 2019-2020 and Saturn in 2018, improving a lot the chances
of observing such events in the near future. Using the derived ephemerides and
the UCAC4 catalogue we managed to identify 5442 candidate stellar occultations
between January 2016 and December 2020 for the 9 satellites studied here. We
discussed how the successful observation of a stellar occultation by these
objects is possible and present some potential occultations.


title:
Identification of promising research directions using machine learning
  aided medical literature analysis

abstract:
  The rapidly expanding corpus of medical research literature presents major
challenges in the understanding of previous work, the extraction of maximum
information from collected data, and the identification of promising research
directions. We present a case for the use of advanced machine learning
techniques as an aide in this task and introduce a novel methodology that is
shown to be capable of extracting meaningful information from large
longitudinal corpora, and of tracking complex temporal changes within it.


title: Confining Metal-Halide Perovskites in Nanoporous Thin Films

abstract:
  Controlling size and shape of semiconducting nanocrystals advances
nanoelectronics and photonics. Quantum confined, inexpensive, solution derived
metal halide perovskites offer narrow band, color-pure emitters as integral
parts of next-generation displays and optoelectronic devices. We use nanoporous
silicon and alumina thin films as templates for the growth of perovskite
nanocrystallites directly within device-relevant architectures without the use
of colloidal stabilization. We find significantly blue shifted
photoluminescence emission by reducing the pore size; normally
infrared-emitting materials become visibly red, green-emitting materials cyan
and blue. Confining perovskite nanocrystals within porous oxide thin films
drastically increases photoluminescence stability as the templates auspiciously
serve as encapsulation. We quantify the template-induced size of the perovskite
crystals in nanoporous silicon with microfocus high-energy X-ray depth
profiling in transmission geometry, verifying the growth of perovskite
nanocrystals throughout the entire thickness of the nanoporous films.
Low-voltage electroluminescent diodes with narrow, blue-shifted emission
fabricated from nanocrystalline perovskites grown in embedded nanoporous
alumina thin films substantiate our general concept for next generation
photonic devices.


title: Student understanding of electric and magnetic fields in materials

abstract:
  We discuss the clusters of resources that emerge when upper-division students
write about electromagnetic fields in linear materials. The data analyzed for
this paper comes from students' written tests in an upper-division electricity
and magnetism course. We examine how these clusters change with time and
context. The evidence shows that students benefit from activating resources
related to the internal structure of the atom when thinking about electric
fields and their effect on materials. We argue that facilitating activation of
certain resources by the instructor in the classroom can affect the plasticity
of those resources in the student, making them more solid and easily activated.
We find that the wording of the questions posed to students affects which
resources are activated, and that students often fill in resources to link
known phenomena to phenomena described by the question when lacking detailed
mental models.


title:
Inter-Technology Backscatter: Towards Internet Connectivity for
  Implanted Devices

abstract:
  We introduce inter-technology backscatter, a novel approach that transforms
wireless transmissions from one technology to another, on the air.
Specifically, we show for the first time that Bluetooth transmissions can be
used to create Wi-Fi and ZigBee-compatible signals using backscatter
communication. Since Bluetooth, Wi-Fi and ZigBee radios are widely available,
this approach enables a backscatter design that works using only commodity
devices.
  We build prototype backscatter hardware using an FPGA and experiment with
various Wi-Fi, Bluetooth and ZigBee devices. Our experiments show we can create
2-11 Mbps Wi-Fi standards-compliant signals by backscattering Bluetooth
transmissions. To show the generality of our approach, we also demonstrate
generation of standards-complaint ZigBee signals by backscattering Bluetooth
transmissions. Finally, we build proof-of-concepts for previously infeasible
applications including the first contact lens form-factor antenna prototype and
an implantable neural recording interface that communicate directly with
commodity devices such as smartphones and watches, thus enabling the vision of
Internet connected implanted devices.


title: Guided-wave Brillouin scattering in air

abstract:
  Here we identify a new form of optomechanical coupling in gas-filled
hollow-core fibers. Stimulated forward Brillouin scattering is observed in air
in the core of a photonic bandgap fiber. A single resonance is observed at 35
MHz, which corresponds to the first excited axial-radial acoustic mode in the
air-filled core. The linewidth and coupling strengths are determined by the
acoustic loss and electrostrictive coupling in air, respectively. A simple
analytical model, refined by numerical simulations, is developed that
accurately predicts the Brillouin coupling strength and frequency from the gas
and fiber parameters. Since this form of Brillouin coupling depends strongly on
both the acoustic and dispersive optical properties of the gas within the
fiber, this new type of optomechanical interaction is highly tailorable. These
results allow for forward Brillouin spectroscopy in dilute gases, could be
useful for sensing and will present a power and noise limitation for certain
applications.


title:
Evaluation of toroidal torque by non-resonant magnetic perturbations in
  tokamaks for resonant transport regimes using a Hamiltonian approach

abstract:
  Toroidal torque generated by neoclassical viscosity caused by external
non-resonant, non-axisymmetric perturbations has a significant influence on
toroidal plasma rotation in tokamaks. In this article, a derivation for the
expressions of toroidal torque and radial transport in resonant regimes is
provided within quasilinear theory in canonical action-angle variables. The
proposed approach treats all low-collisional quasilinear resonant NTV regimes
including superbanana plateau and drift-orbit resonances in a unified way and
allows for magnetic drift in all regimes. It is valid for perturbations on
toroidally symmetric flux surfaces of the unperturbed equilibrium without
specific assumptions on geometry or aspect ratio. The resulting expressions are
shown to match existing analytical results in the large aspect ratio limit.
Numerical results from the newly developed code NEO-RT are compared to
calculations by the quasilinear version of the code NEO-2 at low
collisionalities. The importance of the magnetic shear term in the magnetic
drift frequency and a significant effect of the magnetic drift on drift-orbit
resonances are demonstrated.


title:
Flow-Through Porous Silicon Membranes for Real-Time Label-Free
  Biosensing

abstract:
  A flow-through sensing platform based on open-ended porous silicon (PSi)
microcavity membranes that are compatible with integration in on-chip sensor
arrays is demonstrated. Due to the high aspect ratio of PSi nanopores, the
performance of closed-ended PSi sensors is limited by infiltration challenges
and slow sensor responses when detecting large molecules such as proteins and
nucleic acids. In order to improve molecule transport efficiency and reduce
sensor response time, open-ended PSi nanopore membranes were used in a
flow-through sensing scheme, allowing analyte solutions to pass through the
nanopores. The molecular binding kinetics in these PSi membranes were compared
through experiments and simulation with those from closed-ended PSi films of
comparable thickness in a conventional flow-over sensing scheme. The
flow-through PSi membrane resulted in a six-fold improvement in sensor response
time when detecting a high molecular weight analyte (streptavidin) versus in
the flow-over PSi approach. This work demonstrates the possibility of
integrating multiple flow-through PSi sensor membranes within parallel
microarrays for rapid and multiplexed label-free biosensing.


title:
Distribution of Formation and migration energies of point defects in
  concentrated solid-solution alloys: Ni_{0.5}Co_{0.5}, Ni_{0.5}Fe_{0.5},
  Ni_{0.8}Fe_{0.2} and Ni_{0.8}Cr_{0.2}

abstract:
  Using ab initio calculations and special quasirandom structures, we have
characterized the distribution of defect formation energy and migration barrier
in Ni-based solid-solution alloys: Ni_{0.5}Co_{0.5}, Ni_{0.5}Fe_{0.5},
Ni_{0.8}Fe_{0.2} and Ni_{0.8}Cr_{0.2}. As defect formation energies depend
sensitively on elemental chemical potential, we have developed a
computationally efficient method for determining it which takes into account
the global composition and local short-range order. We find that Fe has the
biggest alloy effects for Ni among these four elements. Our results show that
the distribution of migration energies for vacancies and interstitial have a
region of overlap, which will facilitate the recombination between them.


title: BICEP3 performance overview and planned Keck Array upgrade

abstract:
  BICEP3 is a 520 mm aperture, compact two-lens refractor designed to observe
the polarization of the cosmic microwave background (CMB) at 95 GHz. Its focal
plane consists of modularized tiles of antenna-coupled transition edge sensors
(TESs), similar to those used in BICEP2 and the Keck Array. The increased
per-receiver optical throughput compared to BICEP2/Keck Array, due to both its
faster f/1.7 optics and the larger aperture, more than doubles the combined
mapping speed of the BICEP/Keck program. The BICEP3 receiver was recently
upgraded to a full complement of 20 tiles of detectors (2560 TESs) and is now
beginning its second year of observation (and first science season) at the
South Pole. We report on its current performance and observing plans. Given its
high per-receiver throughput while maintaining the advantages of a compact
design, BICEP3-class receivers are ideally suited as building blocks for a
3rd-generation CMB experiment, consisting of multiple receivers spanning 35 GHz
to 270 GHz with total detector count in the tens of thousands. We present plans
for such an array, the new "BICEP Array" that will replace the Keck Array at
the South Pole, including design optimization, frequency coverage, and
deployment/observing strategies.


title:
A Letter of Intent to Install a milli-charged Particle Detector at LHC
  P5

abstract:
  In this LOI we propose a dedicated experiment that would detect
"milli-charged" particles produced by pp collisions at LHC Point 5. The
experiment would be installed during LS2 in the vestigial drainage gallery
above UXC and would not interfere with CMS operations. With 300 fb$^{-1}$ of
integrated luminosity, sensitivity to a particle with charge
$\mathcal{O}(10^{-3})~e$ can be achieved for masses of $\mathcal{O}(1)$ GeV,
and charge $\mathcal{O}(10^{-2})~e$ for masses of $\mathcal{O}(10)$ GeV,
greatly extending the parameter space explored for particles with small charge
and masses above 100 MeV.


title: The tidal filament of NGC 4660

abstract:
  NGC 4660, in the Virgo cluster, is a well-studied elliptical galaxy which has
a strong disk component (D/T about 0.2-0.3). The central regions including the
disk component have stellar populations with ages about 12-13 Gyr from SAURON
studies. However we report the discovery of a long narrow tidal filament
associated with the galaxy in deep co-added Schmidt plate images and deep CCD
frames, implying that the galaxy has undergone a tidal interaction and merger
within the last few Gyr. The relative narrowness of the filament implies a wet
merger with at least one spiral galaxy involved, but the current state of the
system has little evidence for this. However a 2-component photometric fit
using GALFIT shows much bluer B-V colours for the disk component than for the
elliptical component, which may represent a residual trace of enhanced star
formation in the disk caused by the interaction 1-2 Gyr ago. There are brighter
concentrations within the filament which resemble Tidal Dwarf Galaxies,
although they are at least 40 times fainter. These may represent faint, evolved
versions of these galaxies. A previously detected stripped satellite galaxy
south of the nucleus is seen in our residual image and may imply that the
filament is a tidal stream produced by perigalactic passages of this satellite.


title:
Matter Neutrino Resonance Transitions above a Neutron Star Merger
  Remnant

abstract:
  The Matter-Neutrino Resonance (MNR) phenomenon has the potential to
significantly alter the flavor content of neutrinos emitted from compact object
mergers. We present the first calculations of MNR transitions using neutrino
self interaction potentials and matter potentials generated selfconsistently
from a dynamical model of a three-dimensional neutron star merger. In the
context of the single angle approximation, we find that Symmetric and Standard
MNR transitions occur in both normal and inverted hierarchy scenarios. We
examine the spatial regions above the merger remnant where propagating
neutrinos will encounter the matter neutrino resonance and find that a
significant fraction of the neutrinos are likely to undergo MNR transitions.


title:
Uniaxial strain-induced Kohn anomaly and electron-phonon coupling in
  acoustic phonons of graphene

abstract:
  Recent advances in strain engineering at the nanoscale have shown the
feasibility to modulate the properties of graphene. Although the
electron-phonon (e-ph) coupling and Kohn anomalies in graphene define the
phonon branches contributing to the resonance Raman scattering, and is relevant
to the electronic and thermal transport as a scattering source, the evolution
of the e-ph coupling as a function of strain has been less studied. In this
work, the Kohn anomalies and the e-ph coupling in uniaxially strained graphene
along armchair (AC) and zigzag (ZZ) directions were studied by means of density
functional perturbation theory calculations. In addition to the phonon anomaly
at the transversal optical (TO) phonon branch in the K point for pristine
graphene, we found that uniaxial strain induces a discontinuity in the
frequency derivative of the longitudinal acoustic (LA) phonon branch. This
behavior corresponds to the emergence of a Kohn anomaly, as a consequence of a
strain-enhanced e-ph coupling. Thus, the present results for uniaxially
strained graphene contrast with the commonly assumed view that the e-ph
coupling around the K point is only present in the TO phonon branch.


title:
Unifying Registration based Tracking: A Case Study with Structural
  Similarity

abstract:
  This paper adapts a popular image quality measure called structural
similarity for high precision registration based tracking while also
introducing a simpler and faster variant of the same. Further, these are
evaluated comprehensively against existing measures using a unified approach to
study registration based trackers that decomposes them into three constituent
sub modules - appearance model, state space model and search method. Several
popular trackers in literature are broken down using this method so that their
contributions - as of this paper - are shown to be limited to only one or two
of these submodules. An open source tracking framework is made available that
follows this decomposition closely through extensive use of generic
programming. It is used to perform all experiments on four publicly available
datasets so the results are easily reproducible. This framework provides a
convenient interface to plug in a new method for any sub module and combine it
with existing methods for the other two. It can also serve as a fast and
flexible solution for practical tracking needs due to its highly efficient
implementation.


title: Merger Hydrodynamics of the Luminous Cluster RXJ1347.5-1145

abstract:
  We present an analysis of the complex gas hydrodynamics in the X-ray luminous
galaxy cluster RXJ1347.5-1145 caught in the act of merging with a subcluster to
its southeast using a combined $186$ ks Chandra exposure, $2.5$ times greater
than previous analyses. The primary cluster hosts a sloshing cold front spiral
traced by four surface brightness edges $5.^{\prime \prime}85^{+0.04}_{-0.03}$
west, $7.^{\prime \prime}10^{+0.07}_{-0.03}$ southeast, $11.^{\prime
\prime}5^{+1.3}_{-1.2}$ east, and $16.^{\prime \prime}7^{+0.3}_{-0.5}$
northeast from the primary central dominant galaxy, suggesting the merger is in
the plane of the sky. We measure temperature and density ratios across these
edges, confirming they are sloshing cold fronts. We observe the eastern edge of
the subcluster infall shock, confirming the observed subcluster is traveling
from the southwest to the northeast in a clockwise orbit. We measure a shock
density contrast of $1.38^{+0.16}_{-0.15}$ and infer a Mach number
$1.25\pm0.08$ and a shock velocity of $2810^{+210}_{-240}$ km s$^{-1}$.
Temperature and entropy maps show cool, low entropy gas trailing the subcluster
in a southwestern tail, consistent with core shredding. Simulations suggest a
perturber in the plane of the sky on a clockwise orbit would produce a sloshing
spiral winding counterclockwise, opposite to that observed. The most compelling
solution to this discrepancy is that the observed southeastern subcluster is on
its first passage, shock heating gas during its clockwise infall, while the
main cluster's clockwise cold front spiral formed from earlier encounters with
a second perturber orbiting counterclockwise.


title:
Certain uncertainty: using pointwise error estimates in super-resolution
  microscopy

abstract:
  Point-wise localization of individual fluorophores is a critical step in
super-resolution microscopy and single particle tracking. Although the methods
are limited by the accuracy in localizing individual flourophores, this
point-wise accuracy has so far only been estimated by theoretical best case
approximations, disregarding for example motional blur, out of focus broadening
of the point spread function and time varying changes in the fluorescence
background. Here, we show that pointwise localization uncertainty can be
accurately estimated directly from imaging data using a Laplace approximation
constrained by simple mircoscope properties. We further demonstrate that the
estimated localization uncertainty can be used to improve downstream
quantitative analysis, such as estimation of diffusion constants and detection
of changes in molecular motion patterns. Most importantly, the accuracy of
actual point localizations in live cell super-resolution microscopy can be
improved beyond the information theoretic lower bound for localization errors
in individual images, by modeling the fluorophores' movement and accounting for
their point-wise localization uncertainty.

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


title:
Analytic torsion of arithmetic quotients of the symmetric space
  SL(n,R)/SO(n)

abstract:
  In this paper we define a regularized version of the analytic torsion for
arithmetic quotients of the symmetric space SL(n,R)/\SO(n). The definition is
based on the study of the renormalized trace of the corresponding heat
operators, which is defined as the geometric side of the Arthur trace formula
applied to the heat operator


title: Hektor - an exceptional D-type family among Jovian Trojans

abstract:
  In this work, we analyze Jovian Trojans in the space of suitable resonant
elements and we identify clusters of possible collisional origin by two
independent methods: the hierarchical clustering and a so-called "randombox".
Compared to our previous work (Bro\v{z} and Rozehnal 2011), we study a twice
larger sample. Apart from Eurybates, Ennomos and $1996\,\rm RJ$ families, we
have found three more clusters --- namely families around asteroids
(20961)~Arkesilaos, (624)~Hektor in the $L_4$ libration zone and
(247341)~$2001\,\rm UV_{209}$ in $L_5$. The families fulfill our stringent
criteria, i.e. a high statistical significance, an albedo homogeneity and a
steeper size-frequency distribution than that of background. In order to
understand their nature, we simulate their long term collisional evolution with
the Boulder code (Morbidelli et al. 2009) and dynamical evolution using a
modified SWIFT integrator (Levison and Duncan, 1994). Within the framework of
our evolutionary model, we were able to constrain the the age of the Hektor
family to be either 1 to 4 Gyr or, less likely, 0.1 to 2.5 Gyr, depending on
initial impact geometry. Since (624) Hektor itself seems to be a bilobed--shape
body with a satellite (Marchis et al. 2014), i.e. an exceptional object, we
address its association with the D--type family and we demonstrate that the
moon and family could be created during a single impact event. We simulated the
cratering event using a Smoothed Particle Hydrodynamics (SPH, Benz and Asphaug,
1994). This is also the first case of a family associated with a D--type parent
body.


title:
The Correlation Between Halo Mass and Stellar Mass for the Most Massive
  Galaxies in the Universe

abstract:
  We present measurements of the clustering of galaxies as a function of their
stellar mass in the Baryon Oscillation Spectroscopic Survey. We compare the
clustering of samples using 12 different methods for estimating stellar mass,
isolating the method that has the smallest scatter at fixed halo mass. In this
test, the stellar mass estimate with the smallest errors yields the highest
amplitude of clustering at fixed number density. We find that the PCA stellar
masses of Chen etal (2012) clearly have the tightest correlation with halo
mass. The PCA masses use the full galaxy spectrum, differentiating them from
other estimates that only use optical photometric information. Using the PCA
masses, we measure the large-scale bias as a function of Mgal for galaxies with
logMgal>=11.4, correcting for incompleteness at the low-mass end of our
measurements. Using the abundance-matching ansatz to connect dark matter halo
mass to stellar mass, we construct theoretical models of b(Mgal) that match the
same stellar mass function but have different amounts of scatter in stellar
mass at fixed halo mass, sigma_logM. Using this approach, we find
sigma_logM=0.18^{+0.01}_{-0.02}. This value includes both intrinsic scatter as
well as random errors in the stellar masses. To partially remove the latter, we
use repeated spectra to estimate statistical errors on the stellar masses,
yielding an upper limit to the intrinsic scatter of 0.16 dex.


abstract:
  This paper explores a novel definition of Schnorr randomness for
noncomputable measures. We say $x$ is uniformly Schnorr $\mu$-random if
$t(\mu,x)<\infty$ for all lower semicomputable functions $t(\mu,x)$ such that
$\mu\mapsto\int t(\mu,x)\,d\mu(x)$ is computable. We prove a number of theorems
demonstrating that this is the correct definition which enjoys many of the same
properties as Martin-L\"of randomness for noncomputable measures. Nonetheless,
a number of our proofs significantly differ from the Martin-L\"of case,
requiring new ideas from computable analysis.


title:
Rejection mechanisms for contaminants in polymeric reverse osmosis
  membranes

abstract:
  Despite the success of reverse osmosis (RO) for water purification, the
molecular-level physico-chemical processes of contaminant rejection are not
well understood. Here we carry out NEMD simulations on a model polyamide RO
membrane to understand the mechanisms of transport and rejection of both ionic
and neutral contaminants in water. We observe that the rejection changes
non-monotonously with ion sizes. In particular, the rejection of urea, 2.4 A
radius, is higher than ethanol, 2.6 A radius, and the rejections for organic
solutes, 2.2-2.8 A radius, are lower than Na+, 1.4 A radius, or Cl-, 2.3 A
radius. We show that this can be explained in terms of the solute accessible
intermolecular volume in the membrane and the solute-water pair interaction
energy. If the smallest open spaces in the membrane's molecular structure are
all larger than the hydrated solute, then the solute-water pair interaction
energy does not matter. However, when the open spaces in the polymeric
structure are such that solutes have to shed at least one water molecule to
pass through a portion of the membrane molecular structure, the pair
interaction energy governs solute rejection. The high pair interaction energy
for water molecules in the solvation shell for ions makes the water molecules
difficult to shed, thus enhancing the rejection of ions. On the other hand, the
organic solute-water interaction energies are governed by the water molecules
that are hydrogen bonded to the solute. Urea molecules have more
hydrogen-bonding sites than alcohol molecules, leading to a higher rejection of
urea than occurs for ethanol, a molecule of similar size but with fewer
hydrogen bonding sites. These findings underline the importance of the solute's
solvation shell and solute-water-membrane chemistry in the context of reverse
osmosis, thus providing new insights into solute transport and rejection in RO
membranes.


title: Structure of Porous Sets in Carnot Groups

abstract:
  We show that any Carnot group contains a closed nowhere dense set which has
measure zero but is not $\sigma$-porous with respect to the
Carnot-Carath\'eodory (CC) distance. In the first Heisenberg group we observe
that there exist sets which are porous with respect to the CC distance but not
the Euclidean distance and vice-versa. In Carnot groups we then construct a
Lipschitz function which is Pansu differentiable at no point of a given
$\sigma$-porous set and show preimages of open sets under the horizontal
gradient are far from being porous.


title:
Effect of interface on mid-infrared photothermal response of MoS2 thin
  film grown by pulsed laser deposition

abstract:
  Here we report mid infrared (mid-IR) photothermal response of multi layer
MoS2 thin film grown on crystalline (p-type silicon and c-axis oriented single
crystal sapphire) and amorphous substrates (Si/SiO2 and Si/SiN) by pulsed laser
deposition (PLD) technique. The photothermal response of the MoS2 films was
measured as changes in the resistance of MoS2 films when irradiated with mid IR
(7 to 8.2 {\mu}m) source. We show that it is possible to enhance the
temperature coefficient of resistance (TCR) of the MoS2 thin film by
controlling the interface through proper choice of substrate and growth
conditions. The thin films grown by PLD were characterized using XRD, Raman,
AFM, XPS and TEM. High-resolution transmission electron microscopy (HRTEM)
images show that the MoS2 films grow on sapphire substrate in a layer-by-layer
manner with misfit dislocations. Layer growth morphology is disrupted when
grown on substrates with diamond cubic structure such as silicon due to growth
twin formation. The growth morphology is very different on amorphous substrates
such as Si/SiO2 or Si/SiN. The MoS2 film grown on silicon shows a very high TCR
(-2.9% K-1), mid IR sensitivity (delR/R=5.2 %) and responsivity (8.7 V/W) as
compared to films on other substrates.


title: On the efficient representation and execution of deep acoustic models

abstract:
  In this paper we present a simple and computationally efficient quantization
scheme that enables us to reduce the resolution of the parameters of a neural
network from 32-bit floating point values to 8-bit integer values. The proposed
quantization scheme leads to significant memory savings and enables the use of
optimized hardware instructions for integer arithmetic, thus significantly
reducing the cost of inference. Finally, we propose a "quantization aware"
training process that applies the proposed scheme during network training and
find that it allows us to recover most of the loss in accuracy introduced by
quantization. We validate the proposed techniques by applying them to a long
short-term memory-based acoustic model on an open-ended large vocabulary speech
recognition task.


title: Koll\'ar--Nadel type vanishing theorem

abstract:
  We prove an analytic generalization of Koll\'ar's vanishing theorem, which
contains the Nadel vanishing theorem as a special case.


title: The geometric approach for constructing Sinai-Ruelle-Bowen measures

abstract:
  An important class of `physically relevant' measures for dynamical systems
with hyperbolic behavior is given by Sinai-Ruelle-Bowen (SRB) measures. We
survey various techniques for constructing SRB measures and studying their
properties, paying special attention to the geometric `push-forward' approach.
After describing this approach in the uniformly hyperbolic setting, we review
recent work that extends it to non-uniformly hyperbolic systems.


title:
Cosmology and Astrophysics from Relaxed Galaxy Clusters V: Consistency
  with Cold Dark Matter Structure Formation

abstract:
  This is the fifth in a series of papers studying the astrophysics and
cosmology of massive, dynamically relaxed galaxy clusters. Our sample comprises
40 clusters identified as being dynamically relaxed and hot in Papers I and II
of this series. Here we use constraints on cluster mass profiles from X-ray
data to test some of the basic predictions of cosmological structure formation
in the Cold Dark Matter (CDM) paradigm. We present constraints on the
concentration--mass relation for massive clusters, finding a power-law mass
dependence with a slope of $\kappa_m=-0.16\pm0.07$, in agreement with CDM
predictions. For this relaxed sample, the relation is consistent with a
constant as a function of redshift (power-law slope with $1+z$ of
$\kappa_\zeta=-0.17\pm0.26$), with an intrinsic scatter of $\sigma_{\ln
c}=0.16\pm0.03$. We investigate the shape of cluster mass profiles over the
radial range probed by the data (typically $\sim50$kpc--1Mpc), and test for
departures from the simple Navarro, Frenk & White (NFW) form, for which the
logarithmic slope of the density profile tends to $-1$ at small radii.
Specifically, we consider as alternatives the generalized NFW (GNFW) and
Einasto parametrizations. For the GNFW model, we find an average value of
(minus) the logarithmic inner slope of $\beta=1.02\pm0.08$, with an intrinsic
scatter of $\sigma_\beta=0.22\pm0.07$, while in the Einasto case we constrain
the average shape parameter to be $\alpha=0.29\pm0.04$ with an intrinsic
scatter of $\sigma_\alpha=0.12\pm0.04$. Our results are thus consistent with
the simple NFW model on average, but we clearly detect the presence of
intrinsic, cluster-to-cluster scatter about the average.


title: A new astrobiological model of the atmosphere of Titan

abstract:
  We present results of an investigation into the formation of nitrogen-bearing
molecules in the atmosphere of Titan. We extend a previous model (Li et al.
2015, 2016) to cover the region below the tropopause, so the new model treats
the atmosphere from Titan's surface to an altitude of 1500 km. We consider the
effects of condensation and sublimation using a continuous, numerically stable
method. This is coupled with parameterized treatments of the sedimentation of
the aerosols and their condensates, and the formation of haze particles. These
processes affect the abundances of heavier species such as the nitrogen-bearing
molecules, but have less effect on the abundances of lighter molecules. Removal
of molecules to form aerosols also plays a role in determining the mixing
ratios, in particular of HNC, HC3N and HCN. We find good agreement with the
recently detected mixing ratios of C2H5CN, with condensation playing an
important role in determining the abundance of this molecule below 500 km. Of
particular interest is the chemistry of acrylonitrile (C2H3CN) which has been
suggested by Stevenson et al. (2015) as a molecule that could form biological
membranes in an oxygen-deficient environment. With the inclusion of haze
formation we find good agreement of our model predictions of acrylonitrile with
the available observations.


title: On the definability of Menger spaces which are not /sigma-compact

abstract:
  Hurewicz proved completely metrizable Menger spaces are /sigma-compact. We
extend this to Cech-complete Menger spaces and consistently to projective
Menger metrizable spaces. On the other hand, it is consistent that there is a
co-analytic Menger space that is not /sigma-compact.


title:
Automated construction of maximally localized Wannier functions for
  bands with nontrivial topology

abstract:
  We show that an optimized projection functions method can automatically
construct maximally localized Wannier functions even for bands with nontrivial
topology. We demonstrate this method on a tight-binding model of a
two-dimensional $\mathbb{Z}_2$ topological insulator, on a three-dimensional
strong $\mathbb{Z}_2$ topological insulator, as well as on first-principles
density functional theory calculated valence states of Bi$_2$Se$_3$. In all
cases, the resulting Wannier functions contain large imaginary components and
are more extended than those in the topologically trivial phase.


title: Probabilistic call by push value

abstract:
  We introduce a probabilistic extension of Levy's Call-By-Push-Value. This
extension consists simply in adding a " flipping coin " boolean closed atomic
expression. This language can be understood as a major generalization of
Scott's PCF encompassing both call-by-name and call-by-value and featuring
recursive (possibly lazy) data types. We interpret the language in the
previously introduced denotational model of probabilistic coherence spaces, a
categorical model of full classical Linear Logic, interpreting data types as
coalgebras for the resource comonad. We prove adequacy and full abstraction,
generalizing earlier results to a much more realistic and powerful programming
language.


title: Frequency Shifts Induced by Field Gradients in Muon $g-2$ Experiments

abstract:
  Two prominent efforts aimed at probing beyond Standard Model physics,
searches for a neutron electric dipole moment (EDM) and measurements of the
muon $g-2$ anomalous magnetic moment, employ spin precession techniques. In the
most recent neutron EDM experiment, frequency shifts induced by magnetic field
gradients and $\mathbf{E} \times \mathbf{v}$ motional fields were a significant
source of systematic error. We consider the possibility of a similar effect in
the most recent muon $g-2$ experiment, and find that such an effect could
potentially be as large as $\sim 1$ ppm fractional error, to be compared with
the reported $\sim 0.5$ ppm error.


title: On the Asymptotic Behavior of Variance of PLRS Decompositions

abstract:
  A positive linear recurrence sequence is of the form $H_{n+1} = c_1 H_n +
\cdots + c_L H_{n+1-L}$ with each $c_i \ge 0$ and $c_1 c_L > 0$, with
appropriately chosen initial conditions. There is a notion of a legal
decomposition (roughly, given a sum of terms in the sequence we cannot use the
recurrence relation to reduce it) such that every positive integer has a unique
legal decomposition using terms in the sequence; this generalizes the
Zeckendorf decomposition, which states any positive integer can be written
uniquely as a sum of non-adjacent Fibonacci numbers. Previous work proved not
only that a decomposition exists, but that the number of summands $K_n(m)$ in
legal decompositions of $m \in [H_n, H_{n+1})$ converges to a Gaussian. Using
partial fractions and generating functions it is easy to show the mean and
variance grow linearly in $n$: $a n + b + o(1)$ and $C n + d + o(1)$,
respectively; the difficulty is proving $a$ and $C$ are positive. Previous
approaches relied on delicate analysis of polynomials related to the generating
functions and characteristic polynomials, and is algebraically cumbersome. We
introduce new, elementary techniques that bypass these issues. The key insight
is to use induction and bootstrap bounds through conditional probability
expansions to show the variance is unbounded, and hence $C > 0$ (the mean is
handled easily through a simple counting argument).


title: Generalzed Bessel Recursion Relations

abstract:
  This paper presents the equality of finite index sums of Bessel func- tions
containing arbitrary numbers of terms. These reduce to the familiar three term
recursion formulas in simple cases.


title: Pulse Width Modulation for Speeding Up Quantum Optimal Control Design

abstract:
  This paper focuses on accelerating quantum optimal control design for complex
quantum systems. Based on our previous work [{arXiv:1607.04054}], we combine
Pulse Width Modulation (PWM) and gradient descent algorithm into solving
quantum optimal control problems, which shows distinct improvement of
computational efficiency in various cases. To further apply this algorithm to
potential experiments, we also propose the smooth realization of the optimized
control solution, e.g. using Gaussian pulse train to replace rectangular
pulses. Based on the experimental data of the D-Norleucine molecule, we
numerically find optimal control functions in $3$-qubit and $6$-qubit systems,
and demonstrate its efficiency advantage compared with basic GRAPE algorithm.


title:
On QoS-assured degraded provisioning in service-differentiated
  multi-layer elastic optical networks

abstract:
  The emergence of new network applications is driving network operators to not
only fulfill dynamic bandwidth requirements, but offer various grades of
service. Degraded provisioning provides an effective solution to flexibly
allocate resources in various dimensions to reduce blocking for differentiated
demands when network congestion occurs. In this work, we investigate the novel
problem of online degraded provisioning in service-differentiated multi-layer
networks with optical elasticity. Quality of Service (QoS) is assured by
service-holding-time prolongation and immediate access as soon as the service
arrives without set-up delay. We decompose the problem into degraded routing
and degraded resource allocation stages, and design polynomial-time algorithms
with the enhanced multi-layer architecture to increase the network flexibility
in temporal and spectral dimensions. Illustrative results verify that we can
achieve significant reduction of network service failures, especially for
requests with higher priorities. The results also indicate that degradation in
optical layer can increase the network capacity, while the degradation in
electric layer provides flexible time-bandwidth exchange.


title: Spectrum and electromagnetic transitions of bottomonium

abstract:
  Stimulated by the exciting progress in the observation of new bottomonium
states, we study the bottomonium spectrum. To calculate the mass spectrum, we
adopt a nonrelativistic screened potential model. The radial Schr\"{o}dinger
equation is solved with the three-point difference central method, where the
spin-dependent potentials are dealt with non-perturbatively. With this
treatment, the corrections of the spin-dependent potentials to the wave
functions can be included successfully. Furthermore, we calculate the
electromagnetic transitions of the $nS$ ($n\leq 4$), $nP$ ($n\leq 3$), and $nD$
($n\leq 2$) bottomonium states with a nonrelativistic electromagnetic
transition operator widely applied to meson photoproduction reactions. Our
predicted masses, hyperfine and fine splittings, electromagnetic transition
widths and branching ratios of the bottomonium states are in good agreement
with the available experimental data. Especially, the EM transitions of
$\Upsilon(3S)\to \chi_{b1,2}(1P)\gamma$, which were not well understood in
previous studies, can be reasonably explained by considering the corrections of
the spin-dependent interactions to the wave functions. We also discuss the
observations of the missing bottomonium states by using radiative transitions.
Some important radiative decay chains involving the missing bottomonium states
are suggested to be observed. We hope our study can provide some useful
references to observe and measure the properties of bottomonium mesons in
forthcoming experiments.


title: Test the chiral magnetic effect with isobaric collisions

abstract:
  The quark-gluon matter produced in relativistic heavy-ion collisions may
contain local domains in which P and CP symmetries are not preserved. When
coupled with an external magnetic field, such P- and CP-odd domains will
generate electric currents along the magnetic field --- a phenomenon called the
chiral magnetic effect (CME). Recently, the STAR Collaboration at RHIC and the
ALICE Collaboration at the LHC released data of charge-dependent
azimuthal-angle correlators with features consistent with the CME expectation.
However, the experimental observable is contaminated with significant
background contributions from elliptic-flow-driven effects, which makes the
interpretation of the data ambiguous. In this Letter, we show that the
collisions of isobaric nuclei, $^{96}_{44}$Ru + $^{96}_{44}$Ru and
$^{96}_{40}$Zr + $^{96}_{40}$Zr, provide an ideal tool to disentangle the CME
signal from the background effects. Our simulation demonstrates that the two
collision types at $\sqrt{s_{\rm NN}}=200$ GeV have more than $10\%$ difference
in the CME signal and less than $2\%$ difference in the elliptic-flow-driven
backgrounds for the centrality range of $20-60\%$.


title:
Lifting Subgroups of Symplectic Groups over $\mathbb{Z} / \ell
  \mathbb{Z}$

abstract:
  For a positive integer $g$, let $\mathrm{Sp}_{2g}(R)$ denote the group of $2g
\times 2g$ symplectic matrices over a ring $R$. Assume $g \ge 2$. For a prime
number $\ell$, we give a self-contained proof that any closed subgroup of
$\mathrm{Sp}_{2g}(\mathbb{Z}_\ell)$ which surjects onto
$\mathrm{Sp}_{2g}(\mathbb{Z}/\ell\mathbb{Z})$ must in fact equal all of
$\mathrm{Sp}_{2g}(\mathbb{Z}_\ell)$. The result and the method of proof are
both motivated by group-theoretic considerations that arise in the study of
Galois representations associated to abelian varieties.


title:
The "Riemann Hypothesis" is True for Period Polynomials of Almost All
  Newforms

abstract:
  The period polynomial $r_f(z)$ for a weight $k \geq 3$ newform $f \in
S_k(\Gamma_0(N),\chi)$ is the generating function for special values of
$L(s,f)$. The functional equation for $L(s, f)$ induces a functional equation
on $r_f(z)$. Jin, Ma, Ono, and Soundararajan proved that for all newforms $f$
of even weight $k \ge 4$ and trivial nebetypus, the "Riemann Hypothesis" holds
for $r_f(z)$: that is, all roots of $r_f(z)$ lie on the circle of symmetry $|z|
=1/\sqrt{N}$. We generalize their methods to prove that this phenomenon holds
for all but possibly finitely many newforms $f$ of weight $k \ge 3$ with any
nebentypus. We also show that the roots of $r_f(z)$ are equidistributed if $N$
or $k$ is sufficiently large.


title: Multiuser Energy Diversity in Energy Harvesting Wireless Communications

abstract:
  Energy harvesting communication has raised great research interests due to
its wide applications and feasibility of commercialization. In this paper, we
investigate the multiuser energy diversity. Specifically, we reveal the
throughput gain coming from the increase of total available energy harvested
over time/space and from the combined dynamics of batteries. Considering both
centralized and distributed access schemes, the scaling of the average
throughput over the number of transmitters is studied, along with the scaling
of corresponding available energy in the batteries.


title: Optimal control of many-body quantum dynamics: chaos and complexity

abstract:
  Achieving full control of the time-evolution of a many-body quantum system is
currently a major goal in physics. In this work we investigate the different
ways in which the controllability of a quantum system can be influenced by its
complexity, or even its chaotic properties. By using optimal control theory, we
are able to derive the control fields necessary to drive various physical
processes in a spin chain. Then, we study the spectral properties of such
fields and how they relate to different aspects of the system complexity. We
find that the spectral bandwidth of the fields is, quite generally, independent
of the system dimension. Conversely, the spectral complexity of such fields
does increase with the number of particles. Nevertheless, we find that the
regular o chaotic nature of the system does not affect signficantly its
controllability.


title: Ultra-Weak Time Operators of Schroedinger Operators

abstract:
  In an abstract framework, a new concept on time operator, ultra-weak time
operator, is introduced, which is a concept weaker than that of weak time
operator. Theorems on the existence of an ultra-weak time operator are
established. As an application of the theorems, it is shown that Schroedinger
operators H with potentials V obeying suitable conditions, including the
Hamiltonian of the hydrogen atom, have ultra-weak time operators. Moreover, a
class of Borel measurable functions $f$ such that $f(H)$ has an ultra-weak time
operator is found.


title:
Graph Hausdorff dimension, Kolmogorov complexity and construction of
  fractal graphs

abstract:
  In this paper we introduce and study discrete analogues of Lebesgue and
Hausdorff dimensions for graphs. It turned out that they are closely related to
well-known graph characteristics such as rank dimension and Prague (or
Ne\v{s}et\v{r}il-R\"odl) dimension. It allows us to formally define fractal
graphs and establish fractality of some graph classes. We show, how Hausdorff
dimension of graphs is related to their Kolmogorov complexity. We also
demonstrate fruitfulness of this interdisciplinary approach by discovering a
novel property of general compact metric spaces using ideas from hypergraphs
theory and by proving an estimation for Prague dimension of almost all graphs
using methods from algorithmic information theory.


title:
Mechanical behavior of composite double wall nanotubes from carbon and
  phosphorous

abstract:
  Black phosphorus is not stable when it is exposed to air. When covered or
terminated by single layer carbon atoms, such as graphene carbon nanotube, it
is more strongly protected in the rapid degradation than the bare black
phosphorus. Moreover, due to weak interaction between phosphorus atoms in black
phosphorene, the nanotube obtained by curling single layer black phosphorus is
not as stable as a carbon nanotube at finite temperature. In present work, we
recommend a new 1D material, i.e., composite double wall nanotubes from a black
phosphorus nanotube with a CNT. The dynamic response of the composite DWNTs is
simulated using molecular dynamics approach. The effects of such factors as
temperature, slenderness and configurations of DWNTs are discussed. Comparing
with a single wall BPNT, the composite DWNTs under uniaxial compression shows
some peculiar properties. When the BPNT is embedded in a CNT, the system will
not collapse rapidly even if the BPNT has been damaged seriously.