title:
Scheduling of Dynamic Electric Loads Using Energy Storage and Short Term
  Power Forecasting

abstract:
  In this paper we formulate an optimization approach to schedule electrical
loads given a short term prediction of time-varying power production and the
ability to store only a limited amount of electrical energy. The proposed
approach is unique and versatile as it allows scheduling of electrical loads
that each have their own dynamic power demand during on/off switching, while
also allowing the specification of minimum on/off times for each loads
separately. The optimization approach is formulated as a parallel enumeration
of all possible on/off times of the electrical loads using a moving time
approach in which only a short term power production forecast is needed, while
at the same time taking into account constraints on electrical energy storage
and power delivery of a battery system. It is shown that the complexity of the
optimization (number of enumerations) is limited by the number of data points
in the short term power production forecast and the minimum on/off time of the
electrical loads. The limited complexity along with parallel enumeration allows
real-time operational scheduling of a large number of loads. The simulation
results shown in this paper illustrate that relatively short term power
forecast profiles can be used to effectively schedule dynamic loads with
various dynamic load profiles.


title: Groups in which every non-abelian subgroup is self-normalized

abstract:
  We study groups having the property that every non-abelian subgroup is equal
to its normalizer. This class of groups is closely related to an open problem
posed by Berkovich. We give a full classification of finite groups having the
above property. We also describe all infinite soluble groups in this class.


title:
Discontinuous Galerkin finite element methods for radiative transfer in
  spherical symmetry

abstract:
  The discontinuous Galerkin finite element method (DG-FEM) is successfully
applied to treat a broad variety of transport problems numerically. In this
work, we use the full capacity of the DG-FEM to solve the radiative transfer
equation in spherical symmetry. We present a discontinuous Galerkin method to
directly solve the spherically-symmetric radiative transfer equation as a
two-dimensional problem. The transport equation in spherical atmospheres is
more complicated than in the plane-parallel case due to the appearance of an
additional derivative with respect to the polar angle. The DG-FEM formalism
allows for the exact integration of arbitrarily complex scattering phase
functions, independent of the angular mesh resolution. We show that the
discontinuous Galerkin method is able to describe accurately the radiative
transfer in extended atmospheres and to capture discontinuities or complex
scattering behaviour which might be present in the solution of certain
radiative transfer tasks and can, therefore, cause severe numerical problems
for other radiative transfer solution methods.


title: Coherent Product Superposition for Downlink Multiuser MIMO

abstract:
  In a two-user broadcast channel where one user has full CSIR and the other
has none, a recent result showed that TDMA is strictly suboptimal and a product
superposition requiring non-coherent signaling achieves DoF gains under many
antenna configurations. This work introduces product superposition in the
domain of coherent signaling with pilots, demonstrates the advantages of
product superposition in low-SNR as well as high-SNR, and establishes DoF gains
in a wider set of receiver antenna configurations. Two classes of decoders,
with and without interference cancellation, are studied. Achievable rates are
established by analysis and illustrated by simulations.


title:
Dormant Comets Among the Near-Earth Object Population: A Meteor-Based
  Survey

abstract:
  Dormant comets in the near-Earth object (NEO) population are thought to be
involved in the terrestrial accretion of water and organic materials.
Identification of dormant comets is difficult as they are observationally
indistinguishable from their asteroidal counterparts, however they may have
produced dust during their final active stages which potentially are detectable
today as weak meteor showers at the Earth. Here we present the result of a
reconnaissance survey looking for dormant comets using 13~567~542 meteor orbits
measured by the Canadian Meteor Orbit Radar (CMOR). We simulate the dynamical
evolution of the hypothetical meteoroid streams originated from 407 near-Earth
asteroids in cometary orbits (NEACOs) that resemble orbital characteristics of
Jupiter-family comets (JFCs). Out of the 44 hypothetical showers that are
predicted to be detectable by CMOR, we identify 5 positive detections that are
statistically unlikely to be chance associations, including 3 previously known
associations. This translates to a lower limit to the dormant comet fraction of
$2.0\pm1.7\%$ in the NEO population and a dormancy rate of $\sim
10^{-5}~\mathrm{yr^{-1}}$ per comet. The low dormancy rate confirms disruption
and dynamical removal as the dominant end state for near-Earth JFCs. We also
predict the existence of a significant number of meteoroid streams whose
parents have already been disrupted or dynamically removed.


title:
Admissibility and Exact Observability of Observation Operators for
  Micro-Beam Model: Time and Frequency Domain Approaches

abstract:
  This study focuses on the exact observability of a non-classical
Euler-Bernoulli micro-beam equation. This non-classical model was derived based
on the strain gradient elasticity theory, which is intended to explain the
phenomenon of size effect at the micron scale. Spectral properties of the
corresponding state operator are studied; an asymptotic expression for
eigenvalues is calculated, and eigenfunctions are analyzed in order to check
the necessary conditions for the exact observability of the system. By
examining the eigenfunctions, it is shown that among non-collocated boundary
outputs, only measurement of the non-classical moment at the root of the beam
yields an admissible observation operator and also defines an exactly
observable system. An alternative proof based on the multiplier method, which
is commonly employed in the literature on the observability and controllability
of infinite dimensional dynamical systems, is presented to provide a comparison
between the time and frequency domain approaches.


title:
Controlling vibrational cooling with Zero-Width Resonances: An adiabatic
  Floquet approach

abstract:
  In molecular photodissociation, some specific combinations of laser
parameters (wavelength and intensity) lead to unexpected Zero-Width Resonances
(ZWR), with in principle infinite lifetimes. Their interest in inducing basic
quenching mechanisms have recently been devised in the laser control of
vibrational cooling through filtration strategies [O. Atabek et al., Phys. Rev.
A87, 031403(R) (2013)]. A full quantum adiabatic control theory based on the
adiabatic Floquet Hamiltonian is developed to show how a laser pulse could be
envelop-shaped and frequency-chirped so as to protect a given initial
vibrational state against dissociation, taking advantage from its continuous
transport on the corresponding ZWR, all along the pulse duration. As compared
with previous control scenarios actually suffering from non-adiabatic
contamination, drastically different and much more efficient filtration goals
are achieved. A semiclassical analysis helps in finding and interpreting a
complete map of ZWRs in the laser parameter plane. In addition, the choice of a
given ZWR path, among the complete series identified by the semiclassical
approach, amounts to be crucial for the cooling scheme, targeting a single
vibrational state population left at the end of the pulse, while all others
have almost completely decayed. The illustrative example, offering the
potentiality to be transposed to other diatomics, is Na2 prepared by
photoassociation in vibrationally hot but translationally and rotationally cold
states.


title: Practical quantum computing on encrypted data

abstract:
  The ability to perform computations on encrypted data is a powerful tool for
protecting a client's privacy, especially in today's era of cloud and
distributed computing. In terms of privacy, the best solutions that classical
techniques can achieve are unfortunately not unconditionally secure in the
sense that they are dependent on a hacker's computational power. Here we
theoretically investigate, and experimentally demonstrate with Gaussian
displacement and squeezing operations, a quantum solution that achieves the
unconditional security of a user's privacy using the practical technology of
continuous variables. We demonstrate losses of up to 10 km both ways between
the client and the server and show that security can still be achieved. Our
approach offers a number of practical benefits, which can ultimately allow for
the potential widespread adoption of this quantum technology in future
cloud-based computing networks.


title: An Imitation Game concerning gravitational wave physics

abstract:
  The 'Imitation Game' is a Turing Test played with a human participant instead
of a computer. Here the author, a sociologist, who has been immersed in the
field of gravitational wave physics since 1972, tried to pass an Imitation Game
as a gravitational wave physicist. He already passed such a test in mid-2000s
but this test was more elaborate and compared his performance with that of
other kinds of physicists and with other sociologists as well as gravitational
wave physicists. The test was based on 8 technical questions about
gravitational wave physics asked by Professor Sathyprakash of Cardiff
University. Collins marks compared well with that of the other gravitational
wave physicists and were markedly better than that of other classes of
respondent. Collins also marked the test and it can be seen that the way he
marked was also much closer to the gravitational wave physicists than other
categories. Though Collins's expertise can be shown to have degraded a little
in the last ten years it seems not to have degraded a lot. This is important
for his most recent book on the detection of gravitational waves from a black
hole binary, this being Chapter 14 of this book, which is due to by published
my MIT Press in February 2017.


title:
MHD stagnation point flow toward a linearly-stretching
  thermally-insulated sheet with induced magnetic field

abstract:
  The equations governing the magnetohydrodynamic stagnation point flow toward
a non-conducting, thermally insulated, nonporous, linearly stretching sheet are
cast in a self similar form. Consistent boundary conditions on the velocity,
magnetic field and temperature are invoked. The flow problem involves three
parameters- the magnetic Prandtl number, the magnetic interaction number, and
the ratio of the stretching rate to the strength of the stagnation point flow.
The energy equation includes viscous dissipation and Joule heating, and
introduces the Prandtl number as a fourth parameter. Numerical solutions are
obtained and sample results are presented.


title: Cumulants and Correlation Functions vs the QCD phase diagram

abstract:
  In this paper we discuss the relation of particle number cumulants and
correlation functions. It is argued that measuring couplings of the genuine
multi-particle correlation functions could provide cleaner information on
possible non-trivial dynamics in heavy-ion collisions. We extract integrated
multi-proton correlation functions from the presently available experimental
data on proton cumulants. We find that the STAR data contain significant
four-proton correlations, at least at the lower energies, with indication of
changing dynamics in central collisions. We also find that these correlations
are rather long-ranged in rapidity. Finally, using the Ising model, we
demonstrate how the signs of the multi-proton correlation functions may be used
to exclude certain regions of the phase diagram close to the critical point.


title:
Bilinear-biquadratic spin-1 rings: an SU(2)-symmetric MPS algorithm for
  periodic boundary conditions

abstract:
  An efficient algorithm for SU(2) symmetric matrix product states (MPS) with
periodic boundary conditions (PBC) is proposed and implemented. It is applied
to a study of the spectrum and correlation properties of the spin-1
bilinear-biquadratic Heisenberg model. We characterize the various phases of
this model by the lowest states of the spectrum with angular momentum J = 0, 1,
2 for systems of up to 100 spins. Furthermore, we provide precision results for
the dimerization correlator as well as the string correlator.


title: Frames of most uniform Hubble flow

abstract:
  It has been observed that the locally measured Hubble parameter converges
quickest to the background value and the dipole structure of the velocity field
is smallest in the reference frame of the Local Group of galaxies. We study the
statistical properties of Lorentz boosts with respect to the Cosmic Microwave
Background frame which make the Hubble flow look most uniform around a
particular observer. We use a very large N-Body simulation to extract the
dependence of the boost velocities on the local environment such as
underdensities, overdensities, and bulk flows. We find that the observation is
not unexpected if we are located in an underdensity, which is indeed the case
for our position in the universe. The amplitude of the measured boost velocity
for our location is consistent with the expectation in the standard cosmology.


title: Unique Set Cover on Unit Disks and Unit Squares

abstract:
  We study the Unique Set Cover problem on unit disks and unit squares. For a
given set $P$ of $n$ points and a set $D$ of $m$ geometric objects both in the
plane, the objective of the Unique Set Cover problem is to select a subset
$D'\subseteq D$ of objects such that every point in $P$ is covered by at least
one object in $D'$ and the number of points covered uniquely is maximized,
where a point is covered uniquely if the point is covered by exactly one object
in $D'$. In this paper, (i) we show that the Unique Set Cover is NP-hard on
both unit disks and unit squares, and (ii) we give a PTAS for this problem on
unit squares by applying the mod-one approach of Chan and Hu (Comput. Geom.
48(5), 2015).


title: Room evacuation through two contiguous exits

abstract:
  Current regulations demand that at least two exits should be available for a
safe evacuation during a panic situation. Although the "faster is slower"
effect is expected to take place near the exits, the evacuation time will
improve because of the additional exits. However, rooms having contiguous doors
not always reduce the leaving time as expected. We investigated the relation
between the doors separation and the evacuation performance. We found that
there exists a separation distance range that does not really improve the
evacuation time, or it can even worsen the process performance. To our
knowledge, no attention has been given to this issue in the literature. This
work reports how the pedestrians dynamics differ when the separation distance
between two exit doors changes and how this affects the overall performance.


title: Powers of sums and their homological invariants

abstract:
  Let $R$ and $S$ be standard graded algebras over a field $k$, and $I
\subseteq R$ and $J \subseteq S$ homogeneous ideals. Denote by $P$ the sum of
the extensions of $I$ and $J$ to $R\otimes_k S$. We investigate several
important homological invariants of powers of $P$ based on the information
about $I$ and $J$, with focus on finding the exact formulas for these
invariants. Our investigation exploits certain Tor vanishing property of
natural inclusion maps between consecutive powers of $I$ and $J$. As a
consequence, we provide fairly complete information about the depth and
regularity of powers of $P$ given that $R$ and $S$ are polynomial rings and
either $\text{char}~ k=0$ or $I$ and $J$ are generated by monomials.


title: Staircase of crystal phases of hard-core bosons on the Kagome lattice

abstract:
  We study the quantum phase diagram of a system of hard-core bosons on the
Kagome lattice with nearest-neighbor repulsive interactions, for arbitrary
densities, by means of the hierarchical mean field theory and exact
diagonalization techniques. This system is isomorphic to the spin S=1/2 XXZ
model in presence of an external magnetic field, a paradigmatic example of
frustrated quantum magnetism. In the non-frustrated regime, we find two crystal
phases at densities 1/3 and 2/3 that melt into a superfluid phase when
increasing the hopping amplitude, in semi-quantitative agreement with quantum
Monte Carlo computations. In the frustrated regime and away from half-filling,
we find a series of plateaux with densities commensurate with powers of 1/3.
The broader density plateaux (at densities 1/3 and 2/3) are remnants of the
classical degeneracy in the Ising limit. For densities near half-filling, this
staircase of crystal phases melts into a superfluid, which displays finite
chiral currents when computed with clusters having an odd number of sites. Both
the staircase of crystal phases and the superfluid phase prevail in the
non-interacting limit, suggesting that the lowest dispersionless
single-particle band may be at the root of this phenomenon.


title:
Resistivity of the insulating phase approaching the 2D metal-insulator
  transition: the effect of spin polarization

abstract:
  The resistivities of the dilute, strongly-interacting 2D electron systems in
the insulating phase of a silicon MOSFET are the same for unpolarized electrons
in the absence of magnetic field and for electrons that are fully spin
polarized by the presence of an in-plane magnetic field. In both cases the
resistivity obeys Efros-Shklovskii variable range hopping $\rho(T) = \rho_0
\mbox{exp}[(T_{ES}/T)^{1/2}]$, with $T_{ES}$ and $1/\rho_0$ mapping onto each
other if one applies a shift of the critical density $n_c$ reported earlier.
With and withoug magnetic field, the parameters $T_{ES}$ and $1/\rho_0 =
\sigma_0$ exhibit scaling consistent with critical behavior approaching a
metal-insulator transition.


title: Minimizing length of billiard trajectories in hyperbolic polygons

abstract:
  Closed billiard trajectories in a polygon in the hyperbolic plane can be
coded by the order in which they hit the sides of the polygon. In this paper,
we consider the average length of cyclically related closed billiard
trajectories in ideal hyperbolic polygons and prove the conjecture that this
average length is minimized for regular hyperbolic polygons. The proof uses a
strict convexity property of the geodesic length function in Teichm\"uller
space with respect to the Weil-Petersson metric, a fundamental result
established by Wolpert.


title: Identifying Depression on Twitter

abstract:
  Social media has recently emerged as a premier method to disseminate
information online. Through these online networks, tens of millions of
individuals communicate their thoughts, personal experiences, and social
ideals. We therefore explore the potential of social media to predict, even
prior to onset, Major Depressive Disorder (MDD) in online personas. We employ a
crowdsourced method to compile a list of Twitter users who profess to being
diagnosed with depression. Using up to a year of prior social media postings,
we utilize a Bag of Words approach to quantify each tweet. Lastly, we leverage
several statistical classifiers to provide estimates to the risk of depression.
Our work posits a new methodology for constructing our classifier by treating
social as a text-classification problem, rather than a behavioral one on social
media platforms. By using a corpus of 2.5M tweets, we achieved an 81% accuracy
rate in classification, with a precision score of .86. We believe that this
method may be helpful in developing tools that estimate the risk of an
individual being depressed, can be employed by physicians, concerned
individuals, and healthcare agencies to aid in diagnosis, even possibly
enabling those suffering from depression to be more proactive about recovering
from their mental health.


title: On the role of micro-inertia in enriched continuum mechanics

abstract:
  In this paper the role of gradient micro-inertia terms
$\bar{\eta}\lVert\nabla u_{,t}\rVert^{2}$ and free micro-inertia terms
$\eta\lVert p_{,t}\rVert^{2}$ is investigated to unveil their respective effect
on the dynamical behavior of band-gap metamaterials. We show that the term
$\bar{\eta}\lVert\nabla u_{,t}\rVert^{2}$ alone is only able to disclose
relatively simplified dispersive behaviors. On the other hand, the term
$\eta\lVert p_{,t}\rVert^{2}$ is in charge of the description of the full
complex behavior of band-gap metamaterials. A suitable mixing of the two
micro-inertia terms allows to describe a new feature of the
relaxed-micromorphic model, i.e. the description of a second band-gap occurring
for higher frequencies. We also show that a split of the gradient micro-inertia
$\bar{\eta}\lVert\nabla u_{,t}\rVert^{2}$, in the sense of Cartan-Lie
decomposition of matrices, allows to flatten separately longitudinal and
transverse optic branches thus giving the possibility of a second band-gap.
Finally, we investigate the effect of the gradient inertia
$\bar{\eta}\lVert\nabla u_{,t}\rVert^{2}$ on more classical enriched models as
the Mindlin-Eringen and the internal variable ones. We find that the addition
of such gradient micro-inertia allows for the onset of one band-gap in the
Mindlin-Eringen model and of three band-gaps in the internal variable model. In
this last case, however, non-local effects cannot be accounted for which is a
too drastic simplification for most metamaterials. We conclude that, even when
adding gradient micro-inertia terms, the relaxed micromorphic model remains the
most performing one, among the considered enriched model, for the description
of non-local band-gap metamaterials.


title: Quadratic Equations in Three Variables over Gaussian Integers

abstract:
  We develop an algebraic method of studying of Diophantine quadratic equations
in three variables over the ring of Gaussian integers.


title: Symmetry-free SDP Relaxations for Affine Subspace Clustering

abstract:
  We consider clustering problems where the goal is to determine an optimal
partition of a given point set in Euclidean space in terms of a collection of
affine subspaces. While there is vast literature on heuristics for this kind of
problem, such approaches are known to be susceptible to poor initializations
and getting trapped in bad local optima. We alleviate these issues by
introducing a semidefinite relaxation based on Lasserre's method of moments.
While a similiar approach is known for classical Euclidean clustering problems,
a generalization to our more general subspace scenario is not straightforward,
due to the high symmetry of the objective function that weakens any convex
relaxation. We therefore introduce a new mechanism for symmetry breaking based
on covering the feasible region with polytopes. Additionally, we introduce and
analyze a deterministic rounding heuristic.


title: Three myths about time reversal in quantum theory

abstract:
  Many have suggested that the transformation standardly referred to as 'time
reversal' in quantum theory is not deserving of the name. I argue on the
contrary that the standard definition is perfectly appropriate, and is indeed
forced by basic considerations about the nature of time in the quantum
formalism.


title: Local orientational mobility in regular hyperbranched polymers

abstract:
  We study the dynamics of local bond orientation in regular hyperbranched
polymers modeled by Vicsek fractals. The local dynamics is investigated through
the temporal autocorrelation functions of single bonds and the corresponding
relaxation forms of the complex dielectric susceptibility. We show that the
dynamic behavior of single segments depends on their remoteness from the
periphery rather than on the size of the whole macromolecule. Remarkably, the
dynamics of the core segments (which are most remote from the periphery) shows
a scaling behavior that differs from the dynamics obtained after structural
average. We analyze the most relevant processes of single segment motion and
provide an analytic approximation for the corresponding relaxation times.
Furthermore, we describe an iterative method to calculate the orientational
dynamics in the case of very large macromolecular sizes.


title: Nonminimal Lorentz-Violating Effects in Photon Physics

abstract:
  We study an extension of QED involving a light pseudoscalar (an axion-like
particle), together with a very massive fermion which has Lorentz-violating
interactions with the photon and the pseudoscalar, including a nonminimal
Lorentz-violating coupling. We investigate the low energy effective action for
this model, after integration over the fermion field, and show that interesting
results are obtained, such as the generation of a correction to the standard
coupling between the axion-like particle and the photon, as well as
Lorentz-violating effects in the interaction energy involving electromagnetic
sources such as pointlike charges, steady line currents and Dirac strings.


title:
Influencia del potencial de polarizaci\'on en la deposici\'on de
  pel\'iculas delgadas de NiO

abstract:
  Nickel oxide (NiO) is a binary compound with a lot of applications in the
present technology. NiO thin films were deposited by reactive sputtering
magnetron under several voltage biases applied in the glass substrates (0, 50,
100, 200, 300, 400 and 500 V). Films were characterized by profilometry, X-ray
diffraction, elemental composition and electrical resistivity at room
temperature and at low temperatures. The present work showed that despite the
insulating behavior of substrate the residual stress was reduced at high biases
and the (111) texture was promoted. Electrical resistivity was reduced at high
bias and at low temperatures thermal activation of p-type conduction was
detected.


title:
Option pricing with fractional stochastic volatility and discontinuous
  payoff function of polynomial growth

abstract:
  We consider the pricing problem related to payoffs that can have
discontinuities of polynomial growth. The asset price dynamic is modeled within
the Black and Scholes framework characterized by a stochastic volatility term
driven by a fractional Ornstein-Uhlenbeck process. In order to solve the
aforementioned problem, we consider three approaches. The first one consists in
a suitable transformation of the initial value of the asset price, in order to
eliminate possible discontinuities. Then we discretize both the Wiener process
and the fractional Brownian motion and estimate the rate of convergence of the
related discretized price to its real value, the latter one being impossible to
be evaluated analytically. The second approach consists in considering the
conditional expectation with respect to the entire trajectory of the fractional
Brownian motion (fBm). Then we derive a closed formula which involves only
integral functional depending on the fBm trajectory, to evaluate the price;
finally we discretize the fBm and estimate the rate of convergence of the
associated numerical scheme to the option price. In both cases the rate of
convergence is the same and equals $n^{-rH}$, where $n$ is a number of the
points of discretization, $H$ is the Hurst index of fBm, and $r$ is the
H\"{o}lder exponent of volatility function. The third method consists in
calculating the density of the integral functional depending on the trajectory
of the fBm via Malliavin calculus also providing the option price in terms of
the associated probability density.


title: Johari-Goldstein Relaxation Events Are Metabasin Transitions

abstract:
  We show that by representing quasi-elastic and inelastic neutron scattering
from propylene carbonate (PC) with an explicitly heterogeneous model, we
recover two distinct dynamic signatures in addition to diffusive motion. The
intermediate scattering function provides access to the time-dependence of
these two dynamic processes, and they appear to correspond to transitions
between inherent states and between metabasins on a potential energy landscape.
By fitting the full q-dependence of inelastic scattering, we confirm that that
the Johari-Goldstein ($\beta_{JG}$) relaxation in PC is indistinguishable from
metabasin transitions.


title:
Constraints on SME Coefficients from Lunar Laser Ranging, Very Long
  Baseline Interferometry, and Asteroid Orbital Dynamics

abstract:
  Lorentz symmetry violations can be parametrized by an effective field theory
framework that contains both General Relativity and the Standard Model of
particle physics, called the Standard-Model Extension or SME. We consider in
this work only the pure gravitational sector of the minimal SME. We present new
constraints on the SME coefficients obtained from lunar laser ranging, very
long baseline interferometry, and planetary motions.


title:
Seeing the Forest from the Trees in Two Looks: Matrix Sketching by
  Cascaded Bilateral Sampling

abstract:
  Matrix sketching is aimed at finding close approximations of a matrix by
factors of much smaller dimensions, which has important applications in
optimization and machine learning. Given a matrix A of size m by n,
state-of-the-art randomized algorithms take O(m * n) time and space to obtain
its low-rank decomposition. Although quite useful, the need to store or
manipulate the entire matrix makes it a computational bottleneck for truly
large and dense inputs. Can we sketch an m-by-n matrix in O(m + n) cost by
accessing only a small fraction of its rows and columns, without knowing
anything about the remaining data? In this paper, we propose the cascaded
bilateral sampling (CABS) framework to solve this problem. We start from
demonstrating how the approximation quality of bilateral matrix sketching
depends on the encoding powers of sampling. In particular, the sampled rows and
columns should correspond to the code-vectors in the ground truth
decompositions. Motivated by this analysis, we propose to first generate a
pilot-sketch using simple random sampling, and then pursue more advanced,
"follow-up" sampling on the pilot-sketch factors seeking maximal encoding
powers. In this cascading process, the rise of approximation quality is shown
to be lower-bounded by the improvement of encoding powers in the follow-up
sampling step, thus theoretically guarantees the algorithmic boosting property.
Computationally, our framework only takes linear time and space, and at the
same time its performance rivals the quality of state-of-the-art algorithms
consuming a quadratic amount of resources. Empirical evaluations on benchmark
data fully demonstrate the potential of our methods in large scale matrix
sketching and related areas.


title:
Effect of dissipative environment on collapses and revivals of a
  nonlinear quantum oscillator

abstract:
  We study the dissipative dynamics of a wave packet passing through two
different non-linear media. The effect of dissipation on the phenomenon of
collapses and revivals of a wave packet as it evolves in a Kerr-type non-linear
medium (represented by the Hamiltonian $({a}^{\dag} a)^2$) is investigated. We
find that partial revivals do take place when dissipation values are moderate.
For a certain regime of parameters we find a solution where revivals do not die
even in the presence of dissipation and the non-linearity appears to compensate
for the energy and coherence loss. We consider the next order non-linearity,
represented by the Hamiltonian $({a}^{\dag} a)^3$, where we observe the
phenomena of super revivals. The effect of dissipation in this case has an
additional feature of number dependence for the displaced number states. While
our simulations explore the degree to which the phenomena of collapses and
revivals degrades in a dissipative environment, we also discovered the presence
of a situation where degradation is minimal.


title: Cyclotomic Gaudin models, Miura opers and flag varieties

abstract:
  Let $\mathfrak{g}$ be a semisimple Lie algebra over $\mathbb{C}$. Let $\nu
\in \text{Aut}\, \mathfrak{g}$ be a diagram automorphism whose order divides $T
\in \mathbb{Z}_{\geq 1}$. We define cyclotomic $\mathfrak{g}$-opers over the
Riemann sphere $\mathbb{P}^1$ as gauge equivalence classes of
$\mathfrak{g}$-valued connections of a certain form, equivariant under actions
of the cyclic group $\mathbb{Z}/ T\mathbb{Z}$ on $\mathfrak{g}$ and
$\mathbb{P}^1$. It reduces to the usual notion of $\mathfrak{g}$-opers when $T
= 1$.
  We also extend the notion of Miura $\mathfrak{g}$-opers to the cyclotomic
setting. To any cyclotomic Miura $\mathfrak{g}$-oper $\nabla$ we associate a
corresponding cyclotomic $\mathfrak{g}$-oper. Let $\nabla$ have residue at the
origin given by a $\nu$-invariant rational dominant coweight
$\check{\lambda}_0$ and be monodromy-free on a cover of $\mathbb{P}^1$. We
prove that the subset of all cyclotomic Miura $\mathfrak{g}$-opers associated
with the same cyclotomic $\mathfrak{g}$-oper as $\nabla$ is isomorphic to the
$\vartheta$-invariant subset of the full flag variety of the adjoint group $G$
of $\mathfrak{g}$, where the automorphism $\vartheta$ depends on $\nu$, $T$ and
$\check{\lambda}_0$. The big cell of the latter is isomorphic to $N^\vartheta$,
the $\vartheta$-invariant subgroup of the unipotent subgroup $N \subset G$,
which we identify with those cyclotomic Miura $\mathfrak{g}$-opers whose
residue at the origin is the same as that of $\nabla$. In particular, the
cyclotomic generation procedure recently introduced in [arXiv:1505.07582] is
interpreted as taking $\nabla$ to other cyclotomic Miura $\mathfrak{g}$-opers
corresponding to elements of $N^\vartheta$ associated with simple root
generators.
  We motivate the introduction of cyclotomic $\mathfrak{g}$-opers by
formulating two conjectures which relate them to the cyclotomic Gaudin model of
[arXiv:1409.6937].


title: The fallacy of evidence based policy

abstract:
  The use of science for policy is at the core of a perfect storm generated by
the insurgence of several concurrent crises: of science, of trust, of
sustainability. The modern positivistic model of science for policy, known as
evidence based policy, is based on dramatic simplifications and compressions of
available perceptions of the state of affairs and possible explanations
(hypocognition). This model can result in flawed prescriptions. The flaws
become more evident when dealing with complex issues characterized by
concomitant uncertainties in the normative, descriptive and ethical domains. In
this situation evidence-based policy may concur to the fragility of the social
system. Science plays an important role in reducing the feeling of
vulnerability of humans by projecting a promise of protection against
uncertainties. In many applications quantitative science is used to remove
uncertainty by transforming it into probability, so that mathematical modelling
can play the ritual role of haruspices. This epistemic governance arrangement
is today in crisis. The primacy of science to adjudicate political issues must
pass through an assessment of the level of maturity and effectiveness of the
various disciplines deployed. The solution implies abandoning dreams of
prediction, control and optimization obtained by relying on a limited set of
simplified narratives to define the problem and moving instead to an open
exploration of a broader set of plausible and relevant stories. Evidence based
policy has to be replaced by robust policy, where robustness is tested with
respect to feasibility (compatibility with processes outside human control);
viability (compatibility with processes under human control, in relation to
both the economic and technical dimensions), and desirability domain
(compatibility with a plurality of normative considerations relevant to a
plurality of actors).


title:
Design and development of an ambient-temperature continuously-rotating
  achromatic half-wave plate for CMB polarization modulation on the POLARBEAR-2
  experiment

abstract:
  We describe the development of an ambient-temperature continuously-rotating
half-wave plate (HWP) for study of the Cosmic Microwave Background (CMB)
polarization by the POLARBEAR-2 (PB2) experiment. Rapid polarization modulation
suppresses 1/f noise due to unpolarized atmospheric turbulence and improves
sensitivity to degree-angular-scale CMB fluctuations where the inflationary
gravitational wave signal is thought to exist. A HWP modulator rotates the
input polarization signal and therefore allows a single polarimeter to measure
both linear polarization states, eliminating systematic errors associated with
differencing of orthogonal detectors. PB2 projects a 365-mm-diameter focal
plane of 7,588 dichroic, 95/150 GHz transition-edge-sensor bolometers onto a
4-degree field of view that scans the sky at $\sim$ 1 degree per second. We
find that a 500-mm-diameter ambient-temperature sapphire achromatic HWP
rotating at 2 Hz is a suitable polarization modulator for PB2. We present the
design considerations for the PB2 HWP, the construction of the HWP optical
stack and rotation mechanism, and the performance of the fully-assembled HWP
instrument. We conclude with a discussion of HWP polarization modulation for
future Simons Array receivers.


title: Dark Matter Results from First 98.7-day Data of PandaX-II Experiment

abstract:
  We report the WIMP dark matter search results using the first physics-run
data of the PandaX-II 500 kg liquid xenon dual-phase time-projection chamber,
operating at the China JinPing Underground Laboratory. No dark matter candidate
is identified above background. In combination with the data set during the
commissioning run, with a total exposure of 3.3$\times10^4$ kg-day,the most
stringent limit to the spin-independent interaction between the ordinary and
WIMP dark matter is set for a range of dark matter mass between 3.5 and 1000
GeV/c$^2$. The best upper limit on the scattering cross section is found
$2.5\times 10^{-46}$ cm$^2$ for the WIMP mass 40 GeV/c$^2$ at 90% confidence
level.


title:
Nanostructures mechanically stable with desirable characteristic field
  enhancement factor: a response from scale invariance in electrostatics

abstract:
  This work presents an accurate numerical study of the electrostatics of
systems formed by individual nanostructure mounted on support substrate tip, a
theoretical prototype for applications in field electron emission or for
construction of tips in probe microscopy requiring high resolution. We modeled
substrate tip with height $h_1$, radius $r_{1}$ and characteristic field
enhancement factor (FEF) $\gamma_1$, and the top nanostructure with height
$h_2$, radius $r_{2}<r_{1}$ and FEF $\gamma_2$, both hemisphere on post-like
structures. Then, nanostructure mounted on support substrate tip has
characteristic FEF, $\gamma_{C}$. Defining the relative difference $\eta_R
\equiv (\gamma_{C} - \gamma_{1})/ (\gamma_{3} - \gamma_{1})$, where
$\gamma_{3}$ corresponds to reference FEF for a hemisphere on post structure
with radius $r_3=r_2$ and height $h_3=h_1 + h_2$, our results suggest, from
numerical solution of Laplace's equation using a finite element scheme, a
scaling $\eta_R = f(u\equiv\lambda\theta^{-1})$, where $\lambda\equiv
h_{2}/h_1$ and $\theta \equiv r_1/r_2$. Given a characteristic variable
$u_{c}$, we found, for $u \ll u_{c}$, a power law $\eta_{R} \sim u^{\kappa}$
with $\kappa \approx 0.55$. For $u \gg u_{c}$, $\eta_{R} \approx 1$ providing
conditions where $\gamma_C \rightarrow \gamma_3$. As a consequence of scaling
invariance, it's possible to derive a simple expression for $\gamma_C$, being
possible to predict conditions to produce related systems with a desirable FEF
and that, at the same time, are mechanically stable by presence of substrate
tip. Finally, we also discuss the validity of Schottky's conjecture (SC) for
these systems showing that, while to obey SC is a indicative of scale
invariance, the opposite is not necessarily satisfied. This suggest that a
careful analysis must be done before attribute the SC as a origin of giant FEF
in experiments.


title:
Semi-global Output Feedback Stabilization of Non-Minimum Phase Nonlinear
  Systems

abstract:
  We solve the problem of output feedback stabilization of a class of nonlinear
systems, which may have unstable zero dynamics. We allow for any globally
stabilizing full state feedback control scheme to be used as long as it
satisfies a particular ISS condition. We show semi-global stability of the
origin of the closed-loop system and also the recovery of the performance of an
auxiliary system using a full-order observer. This observer is based on the use
of an extended high-gain observer to provide estimates of the output and its
derivatives plus a signal used by an extended Kalman filter to provide
estimates of the remaining states. Finally, we provide a simulation example
that illustrates the design procedure.


title: On the Ubiquity of Web Tracking: Insights from a Billion-Page Web Crawl

abstract:
  We perform a large-scale analysis of third-party trackers on the World Wide
Web from more than 3.5 billion web pages of the CommonCrawl 2012 corpus. We
extract a dataset containing more than 140 million third-party embeddings in
over 41 million domains. To the best of our knowledge, this constitutes the
largest web tracking dataset collected so far, and exceeds related studies by
more than an order of magnitude in the number of domains and web pages
analyzed. We perform a large-scale study of online tracking, on three levels:
(1) On a global level, we give a precise figure for the extent of tracking,
give insights into the structure of the `online tracking sphere' and analyse
which trackers are used by how many websites. (2) On a country-specific level,
we analyse which trackers are used by websites in different countries, and
identify the countries in which websites choose significantly different
trackers than in the rest of the world. (3) We answer the question whether the
content of websites influences the choice of trackers they use, leveraging more
than 90 thousand categorized domains. In particular, we analyse whether highly
privacy-critical websites make different choices of trackers than other
websites. Based on the performed analyses, we confirm that trackers are
widespread (as expected), and that a small number of trackers dominates the web
(Google, Facebook and Twitter). In particular, the three tracking domains with
the highest PageRank are all owned by Google. The only exception to this
pattern are a few countries such as China and Russia. Our results suggest that
this dominance is strongly associated with country-specific political factors
such as freedom of the press. We also confirm that websites with highly
privacy-critical content are less likely to contain trackers (60% vs 90% for
other websites), even though the majority of them still do contain trackers.


title: Evolution of density and velocity profiles of matter in large voids

abstract:
  We analyse the evolution of cosmological perturbations which leads to the
formation of large voids in the distribution of galaxies. We assume that
perturbations are spherical and all components of the Universe - radiation,
matter and dark energy - are continuous media with ideal fluid energy-momentum
tensors, which interact only gravitationally. Equations of the evolution of
perturbations in the comoving to cosmological background reference frame for
every component are obtained from equations of conservation and Einstein's ones
and are integrated by modified Euler method. Initial conditions are set at the
early stage of evolution in the radiation-dominated epoch, when the scale of
perturbation is mush larger than the particle horizon. Results show how the
profiles of density and velocity of matter in spherical voids with different
overdensity shells are formed.


title: gvnn: Neural Network Library for Geometric Computer Vision

abstract:
  We introduce gvnn, a neural network library in Torch aimed towards bridging
the gap between classic geometric computer vision and deep learning. Inspired
by the recent success of Spatial Transformer Networks, we propose several new
layers which are often used as parametric transformations on the data in
geometric computer vision. These layers can be inserted within a neural network
much in the spirit of the original spatial transformers and allow
backpropagation to enable end-to-end learning of a network involving any domain
knowledge in geometric computer vision. This opens up applications in learning
invariance to 3D geometric transformation for place recognition, end-to-end
visual odometry, depth estimation and unsupervised learning through warping
with a parametric transformation for image reconstruction error.


title: Modes of the Kerr geometry with purely imaginary frequencies

abstract:
  In this paper, we examine the behavior of modes of the Kerr geometry when the
mode's frequency is purely imaginary. We demonstrate that quasinormal modes
must be polynomial in nature if their frequency is purely imaginary, and
present a method for computing such modes. The nature of these modes, however,
is not always easy to determine. Some of the polynomial modes we compute are
quasinormal modes. However, some are simultaneously quasinormal modes and total
transmission modes, while others fail to satisfy the requisite boundary
conditions for either. This analysis is, in part, an extension of the results
known for Schwarzschild black holes, but clarifies misconceptions for the
behavior of modes when the black hole has angular momentum. We also show that
the algebraically special modes of Kerr with m=0 have an additional branch of
solutions not seen before in the literature. All of these results are in
precise agreement with new numerical solutions for sequences of gravitational
quasinormal modes of Kerr. However, we show that some prior numerical and
analytic results concerning the existence of quasinormal modes of Kerr with
purely imaginary frequencies were incorrect.


title: Model Structures on Categories of Models of Type Theories

abstract:
  Models of dependent type theories are contextual categories with some
additional structure. We prove that if a theory $T$ has enough structure, then
the category $T\text{-}\mathbf{Mod}$ of its models carries the structure of a
model category. We also show that if $T$ has $\Sigma$ types, then weak
equivalences can be characterized in terms of homotopy categories of models.


title: On the dark matter haloes inner structure and galaxy morphology

abstract:
  In the present paper, we extend the study of Del Popolo (2010) to determine
the slope of the inner density profile of galaxy haloes with different
morphologies. We study how galaxy morphology changes the relation between the
inner slope of the galaxy halo density profile, $\alpha$, and the stellar mass,
$M_{*}$, or rotation velocity $V_{\rm rot}$. For this, we use the model of Del
Popolo (2009) in combination with observed data from the Romanowsky \& Fall
(2012) sample of elliptical and spiral galaxies, the Local Group sample
compiled by McConnachie (2012), and the simulation results by Cloet-Osselaer et
al. (2014). We find that the slope $\alpha$ flattens monotonically, from
$\alpha \simeq -1 $ at $V_{\rm rot} \simeq 250$ km/s, to $\alpha \simeq 0 $.
After $V_{\rm rot}\simeq 25$ km/s the slope starts to steepen. The steepening
happens in the mass range dominated by non-rotationally supported galaxies
(e.g., dSphs) and depends on the level of offset in the angular momentum of
rotationally and non-rotationally dominated galaxies. The steepening is a
consequence of the decrease in baryons content, and angular momentum in
spheroidal dwarf galaxies. We finally compare our result to the SPH simulations
of Di Cintio. Our result is in qualitatively agreement with their simulations,
with the main difference that the inner slope $\alpha$ at small stellar masses
($M_* \lesssim10^{8} M_{\odot}$) is flatter than that in their simulations. As
a result, the claim that finding a core in dwarf galaxies with masses slightly
smaller than $\simeq 10^6 M_{\odot}$, (as in the Di Cintio, or Governato,
supernovae feedback mechanism) would be a problem for the $\Lambda$CDM model
must be probably revised.


title:
Conservative Multi-Dimensional Semi-Lagrangian Finite Difference Scheme:
  Stability and Applications to the Kinetic and Fluid Simulations

abstract:
  In this paper, we propose a mass conservative semi-Lagrangian finite
difference scheme for multi-dimensional problems without dimensional splitting.
The semi-Lagrangian scheme, based on tracing characteristics backward in time
from grid points, does not necessarily conserve the total mass. To ensure mass
conservation, we propose a conservative correction procedure based on a flux
difference form. Such procedure guarantees local mass conservation, while
introducing time step constraints for stability. We theoretically investigate
such stability constraints from an ODE point of view by assuming exact
evaluation of spatial differential operators and from the Fourier analysis for
linear PDEs.
  The scheme is tested by classical two dimensional linear passive-transport
problems, such as linear advection, rotation and swirling deformation. The
scheme is applied to solve the nonlinear Vlasov-Poisson system using a a high
order tracing mechanism proposed in [Qiu and Russo, 2016]. Such high order
characteristics tracing scheme is generalized to the nonlinear guiding center
Vlasov model and incompressible Euler system. The effectiveness of the proposed
conservative semi-Lagrangian scheme is demonstrated numerically by our
extensive numerical tests.


title:
Search for low-mass WIMPs in a 0.6 kg day exposure of the DAMIC
  experiment at SNOLAB

abstract:
  We present results of a dark matter search performed with a 0.6 kg day
exposure of the DAMIC experiment at the SNOLAB underground laboratory. We
measure the energy spectrum of ionization events in the bulk silicon of
charge-coupled devices down to a signal of 60 eV electron equivalent. The data
are consistent with radiogenic backgrounds, and constraints on the
spin-independent WIMP-nucleon elastic-scattering cross section are accordingly
placed. A region of parameter space relevant to the potential signal from the
CDMS-II Si experiment is excluded using the same target for the first time.
This result obtained with a limited exposure demonstrates the potential to
explore the low-mass WIMP region (<10 GeV/$c^{2}$) of the upcoming DAMIC100, a
100 g detector currently being installed in SNOLAB.

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


title: Set-Valued Tableaux & Generalized Catalan Numbers

abstract:
  Standard set-valued Young tableaux are a generalization of standard Young
tableaux in which cells may contain more than one integer, with the added
conditions that every integer at position $(i,j)$ must be smaller than every
integer at positions $(i,j+1)$ and $(i+1,j)$. This paper explores the
combinatorics of standard set-valued Young tableaux with two-rows, and how
those tableaux may be used to provide new combinatorial interpretations of
generalized Catalan numbers. New combinatorial interpretations are provided for
the two-parameter Fuss-Catalan numbers (Raney numbers), the rational Catalan
numbers, and the solution to the so-called "generalized tennis ball problem".
Methodologies are then introduced for the enumeration of standard set-valued
Young tableaux, prompting explicit formulas for the general two-row case. The
paper closes by drawing a bijection between arbitrary classes of two-row
standard set-valued Young tableaux and collections of two-dimensional lattice
paths that lie weakly below a unique maximal path.


title: \'Etale dynamical systems and topological entropy

abstract:
  In this paper, we consider two questions about topological entropy of
dynamical systems. We propose to resolve these questions by the same approach
of using \'etale analogs of topological and algebraic dynamical systems.
  The first question is to define topological entropy for a topological
dynamical system $(f,X,\Omega )$. The main idea is to make use - in addition to
invariant compact subspaces of $(X,\Omega )$ - of compactifications of \'etale
covers $\pi :(f',X',\Omega ')\rightarrow (f,X,\Omega )$, that is $\pi \circ
f'=f\circ \pi$ and the fibers of $\pi $ are all finite. We prove some basic
results and propose a conjecture, whose validity allows us to prove further
results.
  The second question is to define topological entropy for algebraic dynamical
systems, with the requirement that it should be as close to the pullback on
cohomology groups as possible. To this end, we develop an \'etale analog of
algebraic dynamical systems.


title: Gauge anomalies in Lorentz-violating QED

abstract:
  In this work we study the issue of gauge anomalies in Lorentz-violating QED.
To do so, we opt to use the Becchi-Rouet-Stora-Tyutin formalism within the
algebraic renormalization approach, reducing our study to a cohomology problem.
Since this approach is independent of the renormalization scheme, the results
obtained here are expected to be general. We find that the Lorentz-violating
QED is free of gauge anomalies to all orders in perturbation theory.


title:
Quantifying Uncertainties in Fault Slip Distribution during the T\=ohoku
  Tsunami using Polynomial Chaos

abstract:
  An efficient method for inferring Manning's $n$ coefficients using water
surface elevation data was presented in Sraj et al. (2014) focusing on a test
case based on data collected during the $T\=ohoku$ earthquake and tsunami.
Polynomial chaos expansions were used to build an inexpensive surrogate for the
numerical model Geoclaw, which were then used to perform a sensitivity analysis
in addition to the inversion. In this paper, a new analysis is performed with
the goal of inferring the fault slip distribution of the $T\=ohoku$ earthquake
using a similar problem setup. The same approach to constructing the PC
surrogate did not lead to a converging expansion, however an alternative
approach based on Basis-Pursuit DeNoising was found to be suitable. Our result
shows that the fault slip distribution can be inferred using water surface
elevation data whereas the inferred values minimizes the error between
observations and the numerical model. The numerical approach and the resulting
inversion are presented in this work.


title: On the structure of $\mathcal{N}_p$-spaces in the ball

abstract:
  We study the structure of $\mathcal{N}_p$-spaces in the ball. In particular,
we show that any such space is Moebius-invariant and for $0<p \leq n$, all
$\mathcal{N}_p$-spaces are different. Our results will be of important uses in
the study of operator theory on $\mathcal{N}_p$-spaces.


title:
Three New Results on Continuation Criteria for the 3D Relativistic
  Vlasov-Maxwell System

abstract:
  In this paper, we consider sufficient conditions, called continuation
criteria, for global existence and uniqueness of classical solutions to the
three-dimensional relativistic Vlasov-Maxwell system. In the compact momentum
support setting, we prove that $\|p_{0}^{\frac{18}{5r} -
1+\beta}f\|_{L^{\infty}_{t}L^{r}_{x}L^{1}_{p}} \lesssim 1$, where $1\leq r \leq
2$ and $\beta >0$ is arbitrarily small, is a continuation criteria. The
previously best known continuation criteria in the compact setting is
$\|p_{0}^{\frac{4}{r} - 1+\beta}f\|_{L^{\infty}_{t}L^{r}_{x}L^{1}_{p}} \lesssim
1$, where $1\leq r < \infty$ and $\beta >0$ is arbitrarily small, is due to
work by Kunze. Thus, our continuation criteria is an improvement in the $1\leq
r \leq 2$ range. In addition, we consider also sufficient conditions for a
global existence result to the three-dimensional relativistic Vlasov-Maxwell
system without compact support in momentum space, building on previous work by
Luk-Strain. In their work, it was shown that
$\|p_{0}^{\theta}f\|_{L^{1}_{x}L^{1}_{p}} \lesssim 1$ is a continuation
criteria for the relativistic Vlasov-Maxwell system without compact support in
momentum space for $\theta > 5$. We improve this result to $\theta > 3$. We
also build on another result by Luk-Strain, in which the authors proved the
existence of a global classical solution in the compact momentum support
setting given the condition that there exists a two-dimensional plane on which
the momentum support of the particle density remains fixed. We prove
well-posedness even if the plane varies continuously in time.


title: Evidences of Mott physics in iron pnictides from x-ray spectroscopy

abstract:
  X-ray emission and absorption spectroscopies are jointly used as fast probes
to determine the evolution as a function of doping of the fluctuating local
magnetic moments in K- and Cr- hole-doped BaFe2As2. An increase in the local
moment with hole-doping is found, supporting the theoretical scenario in which
a Mott insulating state that would be realized for half-filled conduction bands
has an influence throughout the phase diagram of these iron-pnictides.


title: Shape Dependence of Holographic R\'enyi Entropy in General Dimensions

abstract:
  We present a holographic method for computing the response of R\'enyi
entropies in conformal field theories to small shape deformations around a flat
(or spherical) entangling surface. Our strategy employs the stress tensor
one-point function in a deformed hyperboloid background and relates it to the
coefficient in the two-point function of the displacement operator. We obtain
explicit numerical results for $d=3,\dots,6$ spacetime dimensions, and also
evaluate analytically the limits where the R\'enyi index approaches 1 and 0 in
general dimensions. We use our results to extend the work of 1602.08493 and
disprove a set of conjectures in the literature regarding the relations between
the R\'enyi shape dependence and the conformal weight of the twist operator. We
also extend our analysis beyond leading order in derivatives in the bulk theory
by studying Gauss-Bonnet gravity.


title: Thermoelectric effects in topological crystalline insulators

abstract:
  We investigate the electrical conductivity and thermoelectric effects in
topological crystalline insulators in the presence of short- and long-range
impurity interactions. We employ the generalized Boltzmann formalism for
anisotropic Fermi surface systems. The conductivity exhibits a local minimum as
doping varies owing to the Van Hove singularity in the density of states
originated from the saddle point in the surface states band structure.
Suppression of the interband scattering of the charge carriers at high-energy
Dirac points results in a maximum in the electrical conductivity. Whenever the
Fermi level passes an extremum in the conductivity, Seebeck coefficient changes
sign. In addition, it is revealed that profound thermoelectric effects can be
attained around these extrema points.


title: Hitomi constraints on the 3.5 keV line in the Perseus galaxy cluster

abstract:
  High-resolution X-ray spectroscopy with Hitomi was expected to resolve the
origin of the faint unidentified E=3.5 keV emission line reported in several
low-resolution studies of various massive systems, such as galaxies and
clusters, including the Perseus cluster. We have analyzed the Hitomi
first-light observation of the Perseus cluster. The emission line expected for
Perseus based on the XMM-Newton signal from the large cluster sample under the
dark matter decay scenario is too faint to be detectable in the Hitomi data.
However, the previously reported 3.5 keV flux from Perseus was anomalously high
compared to the sample-based prediction. We find no unidentified line at the
reported high flux level. Taking into account the XMM measurement uncertainties
for this region, the inconsistency with Hitomi is at a 99% significance for a
broad dark-matter line and at 99.7% for a narrow line from the gas. We do not
find anomalously high fluxes of the nearby faint K line or the Ar satellite
line that were proposed as explanations for the earlier 3.5 keV detections. We
do find a hint of a broad excess near the energies of high-n transitions of
Sxvi (E=3.44 keV rest-frame) -- a possible signature of charge exchange in the
molecular nebula and another proposed explanation for the unidentified line.
While its energy is consistent with XMM pn detections, it is unlikely to
explain the MOS signal. A confirmation of this interesting feature has to wait
for a more sensitive observation with a future calorimeter experiment.


title: Unfolding Convex Polyhedra via Radially Monotone Cut Trees

abstract:
  A notion of "radially monotone" cut paths is introduced as an effective
choice for finding a non-overlapping edge-unfolding of a convex polyhedron.
These paths have the property that the two sides of the cut avoid overlap
locally as the cut is infinitesimally opened by the curvature at the vertices
along the path. It is shown that a class of planar, triangulated convex domains
always have a radially monotone spanning forest, a forest that can be found by
an essentially greedy algorithm. This algorithm can be mimicked in 3D and
applied to polyhedra inscribed in a sphere. Although the algorithm does not
provably find a radially monotone cut tree, it in fact does find such a tree
with high frequency, and after cutting unfolds without overlap. This
performance of a greedy algorithm leads to the conjecture that spherical
polyhedra always have a radially monotone cut tree and unfold without overlap.


title: Strong Coupling and Classicalization

abstract:
  Classicalization is a phenomenon in which a theory prevents itself from
entering into a strong-coupling regime, by redistributing the energy among many
weakly-interacting soft quanta. In this way, the scattering process of some
initial hard quanta splits into a large number of soft elementary processes. In
short, the theory trades the strong coupling for a high-multiplicity of quanta.
At very high energies, the outcome of such a scattering experiment is a
production of soft states of high occupation number that are approximately
classical. It is evident that black hole creation in particle collision at
super-Planckian energies is a result of classicalization, but there is no a
priory reason why this phenomenon must be limited to gravity. If the hierarchy
problem is solved by classicalization, the LHC has a chance of detecting a
tower of new resonances. The lowest-lying resonances must appear right at the
strong coupling scale in form of short-lived elementary particles. The heavier
members of the tower must behave more and more classically: they must be longer
lived and decay into higher numbers of soft quanta.


title: A Non-Parametric Control Chart For High Frequency Multivariate Data

abstract:
  Support Vector Data Description (SVDD) is a machine learning technique used
for single class classification and outlier detection. SVDD based K-chart was
first introduced by Sun and Tsung for monitoring multivariate processes when
underlying distribution of process parameters or quality characteristics depart
from Normality. The method first trains a SVDD model on data obtained from
stable or in-control operations of the process to obtain a threshold $R^2$ and
kernel center a. For each new observation, its Kernel distance from the Kernel
center a is calculated. The kernel distance is compared against the threshold
$R^2$ to determine if the observation is within the control limits. The
non-parametric K-chart provides an attractive alternative to the traditional
control charts such as the Hotelling's $T^2$ charts when distribution of the
underlying multivariate data is either non-normal or is unknown. But there are
challenges when K-chart is deployed in practice. The K-chart requires
calculating kernel distance of each new observation but there are no guidelines
on how to interpret the kernel distance plot and infer about shifts in process
mean or changes in process variation. This limits the application of K-charts
in big-data applications such as equipment health monitoring, where
observations are generated at a very high frequency. In this scenario, the
analyst using the K-chart is inundated with kernel distance results at a very
high frequency, generally without any recourse for detecting presence of any
assignable causes of variation. We propose a new SVDD based control chart,
called as $K_T$ chart, which addresses challenges encountered when using
K-chart for big-data applications. The $K_T$ charts can be used to
simultaneously track process variation and central tendency. We illustrate the
successful use of $K_T$ chart using the Tennessee Eastman process data.


title:
Goos-Hanchen shift of a spin-wave beam transmitted through anisotropic
  interface between two ferromagnets

abstract:
  The main object of investigation in magnonics, spin waves (SWs) are promising
information carriers. Presently the most commonly studied are plane wave-like
SWs and SWs propagating in confined structures, such as waveguides. Here we
consider a Gaussian SW beam obliquely incident on an ultra-narrow interface
between two identical ferromagnetic materials. We use an analytical model and
micromagnetic simulations for an in-depth analysis of the influence of the
interface properties, in particular the magnetic anisotropy, on the
transmission of the SW beam. We derive analytical formulas for the reflectance,
transmittance, phase shift and Goos-Hanchen (GH) shift for beams reflected and
refracted by an interface between two semi-infinite ferromagnetic media; the
results for the refracted beam are the first to be reported to date. The GH
shifts in SW beam reflection and transmission are confirmed by micromagnetic
simulations in the thin-film geometry. We demonstrate the dependence of the
characteristic properties on the magnetic anisotropy at the interface, the
angle of incidence and the frequency of the SWs. We also propose a method for
the excitation of high-quality SW beams in micromagnetic simulations.


title:
A geometric approach to optimal nonequilibrium control: Minimizing
  dissipation in nanomagnetic spin systems

abstract:
  Optimal control of nanomagnets has become an urgent problem for the field of
spintronics as technological tools approach thermodynamically determined limits
of efficiency. In complex, fluctuating systems, like nanomagnetic bits, finding
optimal protocols is challenging, requiring detailed information about the
dynamical fluctuations of the controlled system. We provide a new, physically
transparent derivation of a metric tensor for which the length of a protocol is
proportional to its dissipation. This perspective simplifies nonequilibrium
optimization problems by recasting them in a geometric language. We then
describe a numerical method, an instance of geometric minimum action methods,
that enables computation of geodesics even when the number of control
parameters is large. We apply these methods to two models of nanomagnetic bits:
a simple Landau-Lifshitz-Gilbert description of a single magnetic spin
controlled by two orthogonal magnetic fields and a two dimensional Ising model
in which the field is spatially controlled. These calculations reveal
nontrivial protocols for bit erasure and reversal, providing important,
experimentally testable predictions for ultra-low power computing.


title: Symmetric Graphs have symmetric Matchings

abstract:
  Assume that there is a free group action of automorphisms on a bipartite
graph. If there is a perfect matching on the factor graph, then obviously there
is a perfect matching on the graph. Surprisingly, the reversed is also true for
amenable groups: if there is a perfect matching on the graph, there is also a
perfect matching on the factor graph, i. e. a group invariant ("symmetric")
perfect matching on the graph.


title: Mesh Denoising based on Normal Voting Tensor and Binary Optimization

abstract:
  This paper presents a tensor multiplication based smoothing algorithm that
follows a two step denoising method. Unlike other traditional averaging
approaches, our approach uses an element based normal voting tensor to compute
smooth surfaces. By introducing a binary optimization on the proposed tensor
together with a local binary neighborhood concept, our algorithm better retains
sharp features and produces smoother umbilical regions than previous
approaches. On top of that, we provide a stochastic analysis on the different
kinds of noise based on the average edge length. The quantitative and visual
results demonstrate the performance our method is better compared to state of
the art smoothing approaches.


title:
Classifying Poincar\'e Inequalities and the local geometry of
  RNP-Differentiability Spaces

abstract:
  We characterize complete RNP-differentiability spaces as those spaces which
are rectifiable in terms of doubling metric measure spaces satisfying some
local $(1, p)$-Poincar\'e inequalities. This gives a full characterization of
spaces admitting a strong form of a differentiability structure in the sense of
Cheeger, and provides a partial converse to his theorem. The proof is based on
a new `thickening' construction, which can be used to enlarge subsets into
spaces admitting Poincar\'e inequalities. We also introduce a new notion of
quantitative connectivity which characterizes spaces satisfying local
Poincar\'e inequalities. This characterization is of independent interest, and
has several applications separate from differentiability spaces. We resolve a
question of Tapio Rajala on the existence of Poincar\'e inequalities for the
class of $MCP(K, n)$-spaces which satisfy a weak Ricci-bound. We show that
deforming a geodesic metric measure space by Muckenhoupt weights preserves the
property of possessing a Poincar\'e inequality. Finally, the new condition
allows us to show that many classes of weak, Orlicz and non-homogeneous
Poincar\'e inequalities `self-improve' to classical $(1, q)$-Poincar\'e
inequalities for some $q \in [1,\infty)$, which is related to Keith's and
Zhong's theorem on self-improvement of Poincar\'e inequalities.


title: Much Ado About Time: Exhaustive Annotation of Temporal Data

abstract:
  Large-scale annotated datasets allow AI systems to learn from and build upon
the knowledge of the crowd. Many crowdsourcing techniques have been developed
for collecting image annotations. These techniques often implicitly rely on the
fact that a new input image takes a negligible amount of time to perceive. In
contrast, we investigate and determine the most cost-effective way of obtaining
high-quality multi-label annotations for temporal data such as videos. Watching
even a short 30-second video clip requires a significant time investment from a
crowd worker; thus, requesting multiple annotations following a single viewing
is an important cost-saving strategy. But how many questions should we ask per
video? We conclude that the optimal strategy is to ask as many questions as
possible in a HIT (up to 52 binary questions after watching a 30-second video
clip in our experiments). We demonstrate that while workers may not correctly
answer all questions, the cost-benefit analysis nevertheless favors consensus
from multiple such cheap-yet-imperfect iterations over more complex
alternatives. When compared with a one-question-per-video baseline, our method
is able to achieve a 10% improvement in recall 76.7% ours versus 66.7%
baseline) at comparable precision (83.8% ours versus 83.0% baseline) in about
half the annotation time (3.8 minutes ours compared to 7.1 minutes baseline).
We demonstrate the effectiveness of our method by collecting multi-label
annotations of 157 human activities on 1,815 videos.


title:
Stiff-spring approximation revisited: inertial effects in
  non-equilibrium trajectories

abstract:
  Use of harmonic guiding potentials is the most common method for implementing
steered molecular dynamics (SMD) simulations, performed to obtain potentials of
mean force (PMFs) of molecular systems using non-equilibrium work (NEW)
theorems. Harmonic guiding potentials are also the natural choice in single
molecule force spectroscopy experiments. The stiff spring approximation (SSA)
of Schulten and coworkers enables to use the work performed along SMD
trajectories to obtain the PMF.
  We discuss and demonstrate how a high spring constant, k, required for the
validity of the SSA can violate another requirement of this theory, i.e., the
validity of Brownian dynamics of the system. Violation of the Brownian
condition results in the introduction of kinetic energy contributions to the
external work, performed during SMD simulations. These inertial effects result
in skewed work distributions, rather than the Gaussian distributions predicted
by SSA. The inertial effects also result in broader work distributions, which
worsen the effect of the skewness when calculating work averages. Remarkably,
our results strongly suggest that the skew and width of work distributions are
independent of the average drift velocity and physical asymmetries.
  The skew and broadening of work distributions result in biased estimation of
the PMF. The bias manifests itself in the form of a systematic error that
increases with simulation time. We discuss the proper upper limit for k, such
that the inertial effects are avoided. This limit, used together with the
relation for the lower limit of k, enables to conduct accurate steering while
satisfying the Brownian dynamics. Furthermore, we argue and demonstrate that
using the peak-value (rather than the statistical mean) of the work
distributions vastly reduces the bias in the calculated PMFs and improves the
accuracy.


title: Polynomial Time Algorithm for $2$-Stable Clustering Instances

abstract:
  Clustering with most objective functions is NP-Hard, even to approximate well
in the worst case. Recently, there has been work on exploring different notions
of stability which lend structure to the problem. The notion of stability,
$\alpha$-perturbation resilience, that we study in this paper was originally
introduced by Bilu et al.~\cite{Bilu10}. The works of Awasthi et
al~\cite{Awasthi12} and Balcan et al.~\cite{Balcan12} provide a polynomial time
algorithm for $3$-stable and $(1+\sqrt{2})$-stable instances respectively. This
paper provides a polynomial time algorithm for $2$-stable instances, improving
on and answering an open question in ~\cite{Balcan12}.


title: Chromatic Number of Random Kneser Hypergraphs

abstract:
  Recently, Kupavskii~[{\it On random subgraphs of {K}neser and {S}chrijver
graphs. J. Combin. Theory Ser. A, {\rm 2016}.}] investigated the chromatic
number of random Kneser graphs $\KG_{n,k}(\rho)$ and proved that, in many
cases, the chromatic numbers of the random Kneser graph $\KG_{n,k}(\rho)$ and
the Kneser graph $\KG_{n,k}$ are almost surely closed. He also marked the
studying of the chromatic number of random Kneser hypergraphs
$\KG^r_{n,k}(\rho)$ as a very interesting problem. With the help of
$\Z_p$-Tucker lemma, a combinatorial generalization of the Borsuk-Ulam theorem,
we generalize Kupavskii's result to random general Kneser hypergraphs by
introducing an almost surely lower bound for the chromatic number of them.
Roughly speaking, as a special case of our result, we show that the chromatic
numbers of the random Kneser hypergraph $\KG^r_{n,k}(\rho)$ and the Kneser
hypergraph $\KG^r_{n,k}$ are almost surely closed in many cases. Moreover,
restricting to the Kneser and {S}chrijver graphs, we present a purely
combinatorial proof for an improvement of Kupavskii's results.
  Also, for any hypergraph $\HH$, we present a lower bound for the minimum
number of colors required in a coloring of $\KG^r(\mathcal{H})$ with no
monochromatic $K_{t,\ldots,t}^r$ subhypergraph, where $K_{t,\ldots,t}^r$ is the
complete $r$-uniform $r$-partite hypergraph with $t r$ vertices such that each
of its parts has $t$ vertices. This result generalizes the lower bound for the
chromatic number of $\KG^r(\mathcal{H})$ found by the present authors~[{\it On
the chromatic number of general {K}neser hypergraphs. J. Combin. Theory, Ser.
B, {\rm 2015}.}].


title:
Oscillation-free method for semilinear diffusion equations under noisy
  initial conditions

abstract:
  Noise in initial conditions from measurement errors can create unwanted
oscillations which propagate in numerical solutions. We present a technique of
prohibiting such oscillation errors when solving initial-boundary-value
problems of semilinear diffusion equations. Symmetric Strang splitting is
applied to the equation for solving the linear diffusion and nonlinear
remainder separately. An oscillation-free scheme is developed for overcoming
any oscillatory behavior when numerically solving the linear diffusion portion.
To demonstrate the ills of stable oscillations, we compare our method using a
weighted implicit Euler scheme to the Crank-Nicolson method. The
oscillation-free feature and stability of our method are analyzed through a
local linearization. The accuracy of our oscillation-free method is proved and
its usefulness is further verified through solving a Fisher-type equation where
oscillation-free solutions are successfully produced in spite of random errors
in the initial conditions.


title: Progress Towards a Muonium Gravity Experiment

abstract:
  The gravitational acceleration of antimatter, $\bar g$, has yet to be
directly measured but could change our understanding of gravity, the Universe,
and the possibility of a fifth force. Three avenues are apparent for such a
measurement: antihydrogen, positronium, and muonium, the last requiring a
precision atom interferometer and benefiting from a novel muonium beam under
development. The interferometer and its few-picometer alignment and calibration
systems appear to be feasible. With 100 nm grating pitch, measurements of $\bar
g$ to 10%, 1%, or better can be envisioned. This could constitute the first
gravitational measurement of leptonic matter, of second-generation matter and,
possibly, the first measurement of the gravitational acceleration of
antimatter.


title: Attosecond delays in molecular photoionization

abstract:
  We report measurements of energy-dependent attosecond photoionization delays
between the two outer-most valence shells of N$_2$O and H$_2$O. The combination
of single-shot signal referencing with the use of different metal foils to
filter the attosecond pulse train enables us to extract delays from congested
spectra. Remarkably large delays up to 160 as are observed in N$_2$O, whereas
the delays in H$_2$O are all smaller than 50 as in the photon-energy range of
20-40 eV. These results are interpreted by developing a theory of molecular
photoionization delays. The long delays measured in N$_2$O are shown to reflect
the population of molecular shape resonances that trap the photoelectron for a
duration of up to $\sim$110 as. The unstructured continua of H$_2$O result in
much smaller delays at the same photon energies. Our experimental and
theoretical methods make the study of molecular attosecond photoionization
dynamics accessible.


title:
An exponential B-spline collocation method for fractional sub-diffusion
  equation

abstract:
  In this article, we propose an exponential B-spline collocation method to
approximate the solution of the fractional sub-diffusion equation of Caputo
type. The present method is generated by use of the
Gorenflo-Mainardi-Moretti-Paradisi (GMMP) scheme in time and an efficient
exponential B-spline based method in space. The unique solvability is
rigorously discussed. Its stability is well illustrated via a procedure closely
resembling the classic von Neumann approach. The resulting algebraic system is
tri-diagonal that can rapidly be solved by the known algebraic solver with low
cost and storage. A series of numerical examples are finally carried out and by
contrast to the other algorithms available in the literature, numerical results
confirm the validity and superiority of our method.


title: Symbols of a cosmic order

abstract:
  The world runs on communicated sequences of symbols, e.g. numerals. Examining
both engineered and natural communications networks reveals an unsuspected
order that depends on contact with an unpredictable entity. This order has
three roots. The first is a proof within quantum theory that no evidence can
ever determine its explanation, so that an agent choosing an explanation must
do so unpredictably. The second root is the showing that clocks that step
computers do not "tell time" but serve as self-adjusting symbol-handling agents
that regulate "logically synchronized" motion in response to unpredictable
disturbances. Such a clock-agent has a certain independence as well as the
capacity to communicate via unpredictable symbols with other clock-agents and
to adjust its own tick rate in response to that communication. The third root
is the noticing of unpredictable symbol exchange in natural systems, including
the transmission of symbols found in molecular biology. We introduce a
symbol-handling agent as a role played in some cases by a person, for example a
physicist who chooses an explanation of given experimental outcomes, and in
other cases by some other biological entity, and in still other cases by an
inanimate device, such as a computer-based detector used in physical
measurements. While we forbear to try to explain the propensity of agents at
all levels from cells to civilizations to form and operate networks of
logically synchronized symbol-handling agents, we point to this propensity as
an overlooked cosmic order, an order structured by the unpredictability ensuing
from the proof. Appreciating the cosmic order leads to a conception of agency
that replaces volition by unpredictability and re-conceives the notion of
objectivity in a way that makes a place for agency in the world as described by
physics. Some specific implications for physics are outlined.


title: Dynamics of tidally captured planets in the Galactic Center

abstract:
  Recent observations suggest ongoing planet formation in the innermost parsec
of our Galaxy. The super-massive black hole (SMBH) might strip planets or
planetary embryos from their parent star, bringing them close enough to be
tidally disrupted. We investigate the chance of planet tidal captures by
running three-body encounters of SMBH-star-planet systems with a high-accuracy
regularized code. We show that tidally captured planets have orbits close to
those of their parent star. We conclude that the final periapsis distance of
the captured planet from the SMBH will be much larger than 200 AU, unless its
parent star was already on a highly eccentric orbit.


title: Free box^k Scalar Conformal Field Theory

abstract:
  We consider the generalizations of the free U(N) and O(N) scalar conformal
field theories to actions with higher powers of the Laplacian box^k, in general
dimension d. We study the spectra, Verma modules, anomalies and OPE of these
theories. We argue that in certain d and k, the spectrum contains zero norm
operators which are both primary and descendant, as well as extension operators
which are neither primary nor descendant. In addition, we argue that in even
dimensions d <= 2k, there are well-defined operator algebras which are related
to the box^k theories and are novel in that they have a finite number of
single-trace states.


title:
Electromagnetic Response of Three-dimensional Topological Crystalline
  Insulators

abstract:
  Topological crystalline insulators (TCI) are a new class of materials which
have metallic surface states on select surfaces due to point group crystalline
symmetries. In this letter, we consider a model for a three-dimensional (3D)
topological crystalline insulator with Dirac nodes occurring on a surface that
are protected by the mirror and time reversal symmetry. We demonstrate that the
electromagnetic response for such a system is characterized by a $1$-form
$b_{\mu}$. $b_{\mu}$ can be inferred from the locations of the surface Dirac
nodes in energy-momentum space and couples to the surface Dirac nodes like a
valley gauge field. From both the effective action and analytical band
structure calculations, we show that the vortex core of $\vec b$ or a domain
wall of a component of $\vec b$ can trap surface charges.


title: Mad-Maximized Higgs Pair Analyses

abstract:
  We study Higgs pair production with a subsequent decay to a pair of photons
and a pair of bottoms at the LHC. We use the log-likelihood ratio to identify
the kinematic regions which either allow us to separate the di-Higgs signal
from backgrounds or to determine the Higgs self-coupling. We find that both
regions are separate enough to ensure that details of the background modelling
will not affect the determination of the self-coupling. Assuming dominant
statistical uncertainties we determine the best precision with which the Higgs
self- coupling can be probed in this channel. We finally comment on the same
questions at a future 100 TeV collider.


title:
Particles trajectories in Weibel magnetic filaments with a flow-aligned
  magnetic field

abstract:
  For a Weibel shock to form, two plasma shells have to collide and trigger the
Weibel instability. At saturation, this instability generates in the
overlapping region magnetic filaments with peak field $B_f$. In the absence of
an external guiding magnetic field, these filaments can block the incoming
flow, initiating the shock formation, if their size is larger than the Larmor
radius of the incoming particles in the peak field. Here we show that this
results still holds in the presence of an external magnetic field $B_0$,
provided it is not too high. Yet, for $B_0 \gtrsim B_f/2$, the filaments become
unable to stop any particle, regardless of its initially velocity.


title:
HIDE & SEEK: End-to-End Packages to Simulate and Process Radio Survey
  Data

abstract:
  As several large single-dish radio surveys begin operation within the coming
decade, a wealth of radio data will become available and provide a new window
to the Universe. In order to fully exploit the potential of these data sets, it
is important to understand the systematic effects associated with the
instrument and the analysis pipeline. A common approach to tackle this is to
forward-model the entire system - from the hardware to the analysis of the data
products. For this purpose, we introduce two newly developed, open-source
Python packages: the HI Data Emulator (HIDE) and the Signal Extraction and
Emission Kartographer (SEEK) for simulating and processing single-dish radio
survey data. HIDE forward-models the process of collecting astronomical radio
signals in a single-dish radio telescope instrument and outputs pixel-level
time-ordered-data. SEEK processes the time-ordered-data, removes artifacts from
Radio Frequency Interference (RFI), automatically applies flux calibration, and
aims to recover the astronomical radio signal. The two packages can be used
separately or together depending on the application. Their modular and flexible
nature allows easy adaptation to other instruments and data sets. We describe
the basic architecture of the two packages and examine in detail the noise and
RFI modeling in HIDE, as well as the implementation of gain calibration and RFI
mitigation in SEEK. We then apply HIDE & SEEK to forward-model a Galactic
survey in the frequency range 990 - 1260 MHz based on data taken at the Bleien
Observatory. For this survey, we expect to cover 70% of the full sky and
achieve a median signal-to-noise ratio of approximately 5 - 6 in the cleanest
channels including systematic uncertainties. However, we also point out the
potential challenges of high RFI contamination and baseline removal when
examining the early data from the Bleien Observatory.


title:
Observations of asymmetric velocity fields and gas cooling in the NGC
  4636 galaxy group X-ray halo

abstract:
  This study aims to probe the thermodynamic properties of the hot intragroup
medium (IGM) plasma in the core regions of the NGC 4636 galaxy group by
detailed measurements of several emission lines and their relative intensities.
We analyzed deep XMM-Newton Reflection Grating Spectrometer (RGS) data in five
adjacent spectral regions in the central parts of the NGC 4636 galaxy group. We
examined the suppression of the Fe xvii resonance line (15.01 {\AA}) as
compared to the forbidden lines of the same ion (17.05 {\AA} and 17.10 {\AA}).
The presence and radial dependence of the cooling flow was investigated through
spectral modeling. In addition, a parallel analysis with deep Chandra Advances
CCD Imaging Spectrometer (ACIS) data was conducted to gain additional
information about the thermodynamical properties of the IGM. We find that the
plasma at the group center to the north shows efficient Fe xvii ion resonant
scattering, wheras no resonant scattering was detected at the south side. The
regions featuring resonant scattering coincide with those embodying large
amounts of cool ($kT\lesssim0.4$ keV) gas phases, and the spectral imprints of
cooling gas with a total mass deposition rate of $\sim0.8$ M$_{\odot}$
yr$^{-1}$ within the examined region of $2.4^{\prime}\times 5.0^{\prime}$. We
interpret the results as possible evidence of asymmetric turbulence
distribution in the NGC 4636 IGM: Turbulence dominates the gas dynamics to the
south, while collective gas motions characterize the dynamics to the north.
X-ray images show imprints of energetic AGN at both sides, yet we find evidence
of turbulence heating at the south and gas cooling at the north of the core. We
infer that the observed asymmetry may be the result of the specific observation
angle to the source, or arise from the turbulence driven by core sloshing at
south side.


title:
The dark nemesis of galaxy formation: why hot haloes trigger black hole
  growth and bring star formation to an end

abstract:
  Galaxies fall into two clearly distinct types: `blue-sequence' galaxies that
are rapidly forming young stars, and `red-sequence' galaxies in which star
formation has almost completely ceased. Most galaxies more massive than
$3\times10^{10} M_\odot$ follow the red-sequence while less massive central
galaxies lie on the blue sequence. We show that these sequences are created by
a competition between star formation-driven outflows and gas accretion on to
the supermassive black hole at the galaxy's center. We develop a simple
analytic model for this interaction. In galaxies less massive than
$3\times10^{10} M_\odot$, young stars and supernovae drive a high entropy
outflow that is more buoyant that any diffuse corona. The outflow balances the
rate of gas inflow, preventing high gas densities building up in the central
regions. More massive galaxies, however, are surrounded by a hot corona. We
argue that above a halo mass of $\sim 10^{12} M_\odot$, the supernova-driven
outflow is no longer buoyant and star formation is unable to prevent the build
up of gas in the central regions. This triggers a strongly non-linear response
from the black hole. Its accretion rate rises rapidly, heating the galaxy's
corona, disrupting the incoming supply of cool gas and starving the galaxy of
the fuel for star formation. The host galaxy makes a transition to the red
sequence, and further growth predominantly occurs through galaxy mergers. We
show that the analytic model provides a good description of galaxy evolution in
the EAGLE hydrodynamic simulations, and demonstrate that, so long as star
formation-driven outflows are present, the transition mass scale is almost
independent of subgrid parameter choice. The transition mass disappears
entirely, however, if star formation driven outflows are absent.


title:
Naturalness made easy: two-loop naturalness bounds on minimal SM
  extensions

abstract:
  The main result of this paper is a collection of conservative naturalness
bounds on minimal extensions of the standard model by (vector-like) fermionic
or scalar gauge multiplets. Within, we advocate for an intuitive and physical
concept of naturalness built upon the renormalisation group equations. In the
effective field theory of the standard model plus a gauge multiplet with mass
$M$, the low scale Higgs mass parameter is a calculable function of
$\overline{\rm MS}$ input parameters defined at some high scale $\Lambda_h >
M$. If the Higgs mass is very sensitive to these input parameters, then this
signifies a naturalness problem. To sensibly capture the sensitivity, it is
shown how a sensitivity measure can be rigorously derived as a Bayesian model
comparison, which reduces in a relevant limit to a Barbieri--Giudice-like
fine-tuning measure. This measure is fully generalisable to any perturbative
EFT. The interesting results of our two-loop renormalisation group study are as
follows: for $\Lambda_h=\Lambda_{Pl}$ we find "$10\%$ fine-tuning" bounds on
the masses of various gauge multiplets of $M<\mathcal{O}(1$--$10)$ TeV, with
bounds on fermionic gauge multiplets significantly weaker than for scalars;
these bounds remain finite in the limit $\Lambda_h\to M^+$, weakening to
$M<\mathcal{O}(10$--$100)$ TeV; and bounds on coloured multiplets are no more
severe than for electroweak multiplets, since they only directly correct the
Higgs mass at three-loop.


title:
Complete element abundances of nine stars in the r-process galaxy
  Reticulum II

abstract:
  We present chemical abundances derived from high-resolution Magellan/MIKE
spectra of the nine brightest known red giant members of the ultra-faint dwarf
galaxy Reticulum II. These stars span the full metallicity range of Ret II
(-3.5 < [Fe/H] < -2). Seven of the nine stars have extremely high levels of
r-process material ([Eu/Fe]~1.7), in contrast to the extremely low
neutron-capture element abundances found in every other ultra-faint dwarf
galaxy studied to date. The other two stars are the most metal-poor stars in
the system ([Fe/H] < -3), and they have neutron-capture element abundance
limits similar to those in other ultra-faint dwarf galaxies. We confirm that
the relative abundances of Sr, Y, and Zr in these stars are similar to those
found in r-process halo stars but ~0.5 dex lower than the solar r-process
pattern. If the universal r-process pattern extends to those elements, the
stars in Ret II display the least contaminated known r-process pattern. The
abundances of lighter elements up to the iron peak are otherwise similar to
abundances of stars in the halo and in other ultra-faint dwarf galaxies.
However, the scatter in abundance ratios is large enough to suggest that
inhomogeneous metal mixing is required to explain the chemical evolution of
this galaxy. The presence of low amounts of neutron-capture elements in other
ultra-faint dwarf galaxies may imply the existence of additional r-process
sites besides the source of r-process elements in Ret II. Galaxies like Ret II
may be the original birth sites of r-process enhanced stars now found in the
halo.


title: A 78 Day X-ray Period Detected from NGC 5907 ULX1 by Swift

abstract:
  We report the detection of a $78.1\pm0.5$ day period in the X-ray lightcurve
of the extreme ultraluminous X-ray source NGC 5907 ULX1
($L_{\rm{X,peak}}\sim5\times10^{40}$ erg s$^{-1}$), discovered during an
extensive monitoring program with Swift. These periodic variations are strong,
with the observed flux changing by a factor of $\sim$3-4 between the peaks and
the troughs of the cycle; our simulations suggest that the observed periodicity
is detected comfortably in excess of 3$\sigma$ significance. We discuss
possible origins for this X-ray period, but conclude that at the current time
we cannot robustly distinguish between orbital and super-orbital variations.


title: Classical and quantum particle dynamics in univariate background fields

abstract:
  We investigate deviations from the plane wave model in the interaction of
charged particles with strong electromagnetic fields. A general result is that
integrability of the dynamics is lost when going from lightlike to timelike or
spacelike field dependence. For a special scenario in the classical regime we
show how the radiation spectrum in the spacelike (undulator) case becomes
well-approximated by the plane wave model in the high energy limit, despite the
two systems being Lorentz inequivalent. In the quantum problem, there is no
analogue of the WKB-exact Volkov solution. Nevertheless, WKB and uniform-WKB
approaches give good approximations in all cases considered. Other approaches
that reduce the underlying differential equations from second to first order
are found to miss the correct physics for situations corresponding to barrier
transmission and wide-angle scattering.


title:
Impact of an improved neutrino energy estimate on outflows in neutron
  star merger simulations

abstract:
  Binary neutron star mergers are promising sources of gravitational waves for
ground-based detectors such as Advanced LIGO. Neutron-rich material ejected by
these mergers may also be the main source of r-process elements in the
Universe, while radioactive decays in the ejecta can power bright
electromagnetic post-merger signals. Neutrino-matter interactions play a
critical role in the evolution of the composition of the ejected material,
which significantly impacts the outcome of nucleosynthesis and the properties
of the associated electromagnetic signal. In this work, we present a simulation
of a binary neutron star merger using an improved method for estimating the
average neutrino energies in our energy-integrated neutrino transport scheme.
These energy estimates are obtained by evolving the neutrino number density in
addition to the neutrino energy and flux densities. We show that significant
changes are observed in the composition of the polar ejecta when comparing our
new results with earlier simulations in which the neutrino spectrum was assumed
to be the same everywhere in optically thin regions. In particular, we find
that material ejected in the polar regions is less neutron rich than previously
estimated. Our new estimates of the composition of the polar ejecta make it
more likely that the color and timescale of the electromagnetic signal depend
on the orientation of the binary with respect to an observer's line-of-sight.
These results also indicate that important observable properties of neutron
star mergers are sensitive to the neutrino energy spectrum, and may need to be
studied through simulations including a more accurate, energy-dependent
neutrino transport scheme.