title: Lorentz gauge quantization in synchronous coordinates

abstract:
  It has been shown that the Gupta-Bleuler method of quantization can be used
to impose the Lorentz gauge condition in static space-times but not in
cosmological space-times. This implies that the Gupta-Bleuler approach fails in
general in non-static space-times. More recently, however, the Dirac method of
quantizing constrained dynamical systems has been successfully employed to
impose the Lorentz gauge in conformally flat space-times. In this paper we
generalize this result by using Dirac's method to impose the Lorentz gauge in a
general space-time region where the metric is expressed in synchronous
coordinates.


title:
Evolution of Magnetic Helicity During Eruptive Flares and Coronal Mass
  Ejections

abstract:
  During eruptive solar flares and coronal mass ejections, a non-pot{\-}ential
magnetic arcade with much excess magnetic energy goes unstable and reconnects.
It produces a twisted erupting flux rope and leaves behind a sheared arcade of
hot coronal loops. We suggest that: the twist of the erupting flux rope can be
determined from conservation of magnetic flux and magnetic helicity and
equipartition of magnetic helicity. It depends on the geometry of the initial
pre-eruptive structure.
  Two cases are considered, in the first of which a flux rope is not present
initially but is created during the eruption by the reconnection. In the second
case, a flux rope is present under the arcade in the pre-eruptive state, and
the effect of the eruption and reconnection is to add an amount of magnetic
helicity that depends on the fluxes of the rope and arcade and the geometry.


title:
Stability analysis of Lower Dimensional Gravastars in noncommutative
  geometry

abstract:
  The Ba\~{n}ados, Teitelboim and Zanelli \cite{BTZ1992}, black hole solution
is revamped from the Einstein field equations in (2 + 1)-dimensional anti-de
Sitter spacetime, in a context of noncommutative geometry \cite{Rahaman(2013)}.
In this article, we explore the exact gravastar solutions in three-dimension
anti-de Sitter space given in the same geometry. As a first step we derive BTZ
solution assuming the source of energy density as point-like structures in
favor of smeared objects, where the particle mass M, is diffused throughout a
region of linear size $\sqrt{\alpha}$ and is described by a Gaussian function
of finite width rather than a Dirac delta function. We matched our interior
solution to an exterior BTZ spacetime at a junction interface situated outside
the event horizon. Furthermore, stability analysis is carried out for the
dynamic case for the specific case when $\chi < 0. 214$ under radial
perturbations about static equilibrium solutions. To give theoretical support
we also trying to explore their physical properties and characteristics.


title:
Quantum field theory without divergence: the method of the interaction
  operators

abstract:
  The recently proposed interior boundary conditions approach [S. Teufel and R.
Tumulka: Avoiding Ultraviolet Divergence by Means of Interior Boundary
Conditions, arXiv:1506.00497] is a method for defining Hamiltonians without UV
divergence for quantum field theories. In this approach the interactions
between sectors of the Fock space with different number of particles
(inter-sector interactions) are obtained by extending the domain of the free
Hamiltonian to include functions with singularities. In this paper a similar
but alternative strategy is proposed, in which the inter-sector interactions
are implemented by specific interaction operators. In its simplest form, an
interaction operator is obtained by symmetrizing the asymmetric operator
$\|\hat{\textbf{x}} \|^{-1} \Delta \|\hat {\textbf{x}}\|^{-1}$. The
inter-sector interactions derive from the singularities generated by the
factors $\|\hat{\textbf{x}}\|^{-1}$ enclosing the Laplacian, while the domain
of the interaction operator does not include singular functions. As a
consequence the interaction operators and the free Hamiltonian have a common
dense domain, and they can be added together to form the complete Hamiltonian
with interaction.


title: Compactification of *-autonomous categories

abstract:
  We study the question when a *-autonomous (Mix-)category has a representation
as a $*$-autonomous category of a compact one. We prove that necessary and
sufficient condition is that weak distributivity maps are monic (or,
equivalently epic). For a Mix-category, this condition is, in turn, equivalent
to the requirement that Mix-maps be monic (or epic). We call categories
satisfying this property torsion-free. An important side result is that
torsion-free categories have canonical partial traces.


title:
LHC diphoton excess in a left-right symmetric model with minimal dark
  matter

abstract:
  We construct a model containing a viable dark matter candidate, in the
framework of left-right symmetry, which can explain both width and
cross-section of the observed 750 GeV diphoton excess at the LHC. We introduce
a fermion quintuplet whose neutral component can be a possible dark matter
candidate, whereas the charged components enhance the loop induced coupling of
a 750 GeV singlet scalar with a pair of photons. We study the photo-production
of the singlet scalar and its various decay modes, successfully addressing both
the ATLAS and the CMS diphoton excess.


title: Thermal transport across a continuous metal-insulator transition

abstract:
  The celebrated Wiedemann-Franz (WF) law is believed to be robust in metals as
long as interactions between electrons preserve their fermion-quasiparticle
character. We study thermal transport and the fate of the WF law close to a
continuous metal-insulator transition (MIT) in the Falicov-Kimball model (FKM)
using cluster-dynamical mean-field theory (CDMFT). Surprisingly, as for
electrical transport, we find robust and novel quantum critical scaling in
thermal transport across the MIT. We unearth the deeper reasons for these novel
findings in terms of (i) the specific structure of energy-current correlations
for the FKM and (ii) the microscopic electronic processes which facil- itate
energy transport while simultaneously blocking charge transport close to the
MIT. However, within (C)DMFT, we also find that the WF law survives at T=0 in
the incoherent metal right up to the MIT, even in absence of Landau
quasiparticles.


title:
Relativistic many-body calculation of energies, lifetimes,
  polarizabilities, blackbody radiative shift and hyperfine constants in Lu2+

abstract:
  Energy levels of 30 low-lying states of Lu2+ and allowed electric-dipole
matrix elements between these states are evaluated using a relativistic
all-order method in which all single, double and partial triple excitations of
Dirac-Fock wave functions are included to all orders of perturbation theory.
Matrix elements are critically evaluated for their accuracy and recommended
values of the matrix elements are given together with uncertainty estimates.
Line strengths, transition rates and lifetimes of the metastable 5d(3/2) and
5d(5/2) states are calculated. Recommended values are given for static
polarizabilities of the 6s, 5d and 6p states and tensor polarizabilities of the
5d and 6p(3/2) states. Uncertainties of the polarizability values are estimated
in all cases. The blackbody radiation shift of the 6s(1/2)-5d(5/2) transition
frequency of the Lu2+ ion is calculated with the aid of the recommended scalar
polarizabilities of the 6s(1/2) and 5d(5/2) states. Finally, A and B hyperfine
constants are determined for states of 175Lu2+ with n <= 9. This work provides
recommended values of transition matrix elements, polarizabilities and
hyperfine constants of Lu2+, critically evaluated for accuracy, for benchmark
tests of high-precision theoretical methodology and planning of future
experiments.


title:
Opinion Dynamics in Networks: Convergence, Stability and Lack of
  Explosion

abstract:
  Inspired by the work of [Kempe, Kleinberg, Oren, Slivkins, EC13] we introduce
and analyze a model on opinion formation; the update rule of our dynamics is a
simplified version of that of Kempe et. al. We assume that the population is
partitioned into types whose interaction pattern is specified by a graph.
Interaction leads to population mass moving from types of smaller mass to those
of bigger. We show that starting uniformly at random over all population
vectors on the simplex, our dynamics converges point-wise with probability one
to an independent set. This settles an open problem of Kempe et. al., as
applicable to our dynamics. We believe that our techniques can be used to
settle the open problem for the Kempe et. al. dynamics as well.
  Next, we extend the model of Kempe et. al. by introducing the notion of birth
and death of types, with the interaction graph evolving appropriately. Birth of
types is determined by a Bernoulli process and types die when their population
mass is less than a parameter $\epsilon$. We show that if the births are
infrequent, then there are long periods of "stability" in which there is no
population mass that moves. Finally we show that even if births are frequent
and "stability" is not attained, the total number of types does not explode: it
remains logarithmic in $1/\epsilon$.


title: Structure of numerical algorithms and advanced mechanics

abstract:
  Most elementary numerical schemes found useful for solving classical
trajectory problems are {\it canonical transformations}. This fact should be
make more widely known among teachers of computational physics and Hamiltonian
mechanics. From the perspective of advanced mechanics, there are no bewildering
number of seemingly arbitrary elementary schemes based on Taylor's expansion.
There are only {\it two} canonical first and second order algorithms, on the
basis of which one can comprehend the structures of higher order symplectic and
non-symplectic schemes. This work shows that, from the most elementary
first-order methods to the most advanced fourth-order algorithms, all can be
derived from canonical transformations and Poisson brackets of advanced
mechanics.


title:
2D cellular automaton model for the evolution of active region coronal
  plasmas

abstract:
  We study a 2D cellular automaton (CA) model for the evolution of coronal loop
plasmas. The model is based on the idea that coronal loops are made of
elementary magnetic strands that are tangled and stressed by the displacement
of their footpoints by photospheric motions. The magnetic stress accumulated
between neighbor strands is released in sudden reconnection events or
nanoflares that heat the plasma. We combine the CA model with the Enthalpy
Based Thermal Evolution of Loops (EBTEL) model to compute the response of the
plasma to the heating events. Using the known response of the XRT telescope on
board Hinode we also obtain synthetic data. The model obeys easy to understand
scaling laws relating the output (nanoflare energy, temperature, density,
intensity) to the input parameters (field strength, strand length, critical
misalignment angle). The nanoflares have a power-law distribution with a
universal slope of -2.5, independent of the input parameters. The repetition
frequency of nanoflares, expressed in terms of the plasma cooling time,
increases with strand length. We discuss the implications of our results for
the problem of heating and evolution of active region coronal plasmas.


title:
An investigation of GPU-based stiff chemical kinetics integration
  methods

abstract:
  A fifth-order implicit Runge-Kutta method and two fourth-order exponential
integration methods equipped with Krylov subspace approximations were
implemented for the GPU and paired with the analytical chemical kinetic
Jacobian software pyJac. The performance of each algorithm was evaluated by
integrating thermochemical state data sampled from stochastic partially stirred
reactor simulations and compared with the commonly used CPU-based implicit
integrator CVODE. We estimated that the implicit Runge-Kutta method running on
a single GPU is equivalent to CVODE running on 12-38 CPU cores for integration
of a single global integration time step of 1e-6 s with hydrogen and methane
models. In the stiffest case studied---the methane model with a global
integration time step of 1e-4 s---thread divergence and higher memory traffic
significantly decreased GPU performance to the equivalent of CVODE running on
approximately three CPU cores. The exponential integration algorithms performed
more slowly than the implicit integrators on both the CPU and GPU. Thread
divergence and memory traffic were identified as the main limiters of GPU
integrator performance, and techniques to mitigate these issues were discussed.
Use of a finite-difference Jacobian on the GPU---in place of the analytical
Jacobian provided by pyJac---greatly decreased integrator performance due to
thread divergence, resulting in maximum slowdowns of 7.11-240.96 times; in
comparison, the corresponding slowdowns on the CPU were just 1.39-2.61 times,
underscoring the importance of use of an analytical Jacobian for efficient GPU
integration. Finally, future research directions for working towards enabling
realistic chemistry in reactive-flow simulations via GPU\slash SIMD accelerated
stiff chemical kinetic integration were identified.


title: Good Frames in the Hart-Shelah Example

abstract:
  For a fixed natural number $n \geq 1$, the Hart-Shelah example is an abstract
elementary class (AEC) with amalgamation that is categorical exactly in the
infinite cardinals less than or equal to $\aleph_n$.
  We investigate recently-isolated properties of AECs in the setting of this
example. We isolate the exact amount of type-shortness holding in the example
and show that it has a type-full good $\aleph_{n-1}$-frame which fails the
existence property for uniqueness triples. This gives the first example of such
a frame. Along the way, we develop new tools to build and analyze good frames.


title:
Kepler Flares IV: A Comprehensive Analysis of the Activity of the dM4e
  Star GJ 1243

abstract:
  We present a comprehensive study of the active dM4e star GJ 1243. We use
previous observations and ground-based echelle spectroscopy to determine that
GJ 1243 is a member of the Argus association of field stars, suggesting it is
$\sim 30-50$ Myr old. We analyze eleven months of 1-minute cadence data from
Kepler, presenting Kepler flare frequency distributions, as well as determining
correlations between flare energy, amplitude, duration, and decay time. We find
that the exponent $\alpha$ of the power-law flare energy distribution varies in
time, primarily due to completeness of sample and the low frequency of
high-energy flares. We also find a deviation from a single power law at high
energy. We use ground-based spectroscopic observations simultaneous with the
Kepler data to provide simultaneous photometric and spectroscopic analysis of
three low-energy flares, the lowest-energy dMe flares with detailed spectral
analysis to date on any star. The spectroscopic data from these flares extend
constraints for radiative hydrodynamic (RHD) flare models to a lower energy
regime than has previously been studied. We use this simultaneous spectroscopy
and Kepler photometry to develop approximate conversions from the
\textit{Kepler} bandpass to the traditional $U$ and $B$ bands. This conversion
will be a critical factor in comparing any Kepler flare analyses to the canon
of previous ground-based flare studies.


title: Bounded Gaps Between Products of Distinct Primes

abstract:
  Let $r \ge 2$ be an integer. We adapt the Maynard-Tao sieve to produce the
asymptotically best-known bounded gaps between products of $r$ distinct primes.
Our result applies to positive-density subsets of the primes that satisfy
certain equidistribution conditions. This improves on the work of Thorne and
Sono.


title:
Shift charge and spin photocurrents in Dirac surface states of
  topological insulator

abstract:
  The generation of photocurrent in condensed matter is of main interest for
photovoltaic and optoelectronic applications. Shift current, a nonlinear
photoresponse, has attracted recent intensive attention as a dominant player of
bulk photovoltaic effect in ferroelectric materials. In three dimensional
topological insulators $\text{Bi}_2\text{X}_3$ (X: Te, Se), we find that Dirac
surface states with a hexagonal warping term carry shift current by linearly
polarized light. In addition, shift spin-current is introduced with the
time-reversal symmetry breaking perturbation. The estimate for the magnitudes
of the shift charge- and spin-currents are 0.13$I_0$ and 0.21$I_0$(nA/m) with
the intensity of light $I_0$ measured in $(\text{W}/\text{m}^2)$, respectively,
which can offer a useful method to generate these currents efficiently.


title: Dimensions of multi-fan algebras

abstract:
  Given an arbitrary non-zero simplicial cycle and a generic vector coloring of
its vertices, there is a way to produce a graded Poincare duality algebra
associated with these data. The procedure relies on the theory of volume
polynomials and multi-fans. This construction includes many important examples,
such as cohomology of toric varieties and quasitoric manifolds, and Gorenstein
algebras of triangulated homology manifolds, introduced by Novik and Swartz. In
all these examples the dimensions of graded components of such duality algebras
do not depend on the vector coloring. It was conjectured that the same holds
for any simplicial cycle. We disprove this conjecture by showing that the
colors of singular points of the cycle may affect the dimensions. However, the
colors of smooth points are irrelevant. By using bistellar moves we show that
the number of different dimension vectors arising on a given 3-dimensional
pseudomanifold with isolated singularities is a topological invariant. This
invariant is trivial on manifolds, but nontrivial in general.


title: Notes on Actions of Sets and Groups and Generalized Affine Spaces

abstract:
  Some well-known and less well-known or new notions related to group actions
are surveyed. Some of these notions are used to generalize affine spaces.
Actions are seen as functions with values in transformation monoids


title:
Models of the Cosmological 21 cm Signal from the Epoch of Reionization
  Calibrated with Lyman-alpha and CMB Data

abstract:
  We present here 21 cm predictions from high dynamic range simulations for a
range of reionization histories that have been tested against available
Lyman-alpha and CMB data. We assess the observability of the predicted spatial
21 cm fluctuations by ongoing and upcoming experiments in the late stages of
reionization in the limit in which the hydrogen spin temperature is
significantly larger than the CMB temperature. Models consistent with the
available Lyman-alpha data and CMB measurement of the Thomson optical depth
predict typical values of 10--20 mK^2 for the variance of the 21 cm brightness
temperature at redshifts z=7--10 at scales accessible to ongoing and upcoming
experiments (k < 1 h/cMpc). This is only a factor of a few below the
sensitivity claimed to have been already reached by ongoing experiments in the
signal rms value. Our different models for the reionization history make
markedly different predictions for the redshift evolution and thus frequency
dependence of the 21 cm power spectrum and should be easily discernible by
LOFAR (and later HERA and SKA1) at their design sensitivity. Our simulations
have sufficient resolution to assess the effect of high-density Lyman limit
systems that can self-shield against ionizing radiation and stay 21 cm bright
even if the hydrogen in their surroundings is highly ionized. Our simulations
predict that including the effect of the self-shielded gas in highly ionized
regions reduces the large scale 21 cm power by about 30%.


title:
Charged fermions coupled to $\mathbb{Z}_2$ gauge fields: Superfluidity,
  confinement and emergent Dirac fermions

abstract:
  We consider a 2+1 dimensional model of charged fermions coupled to a
$\mathbb{Z}_2$ gauge field, and study the confinement transition in this
regime. To elucidate the phase diagram of this model, we introduce a method to
handle the Gauss law constraint within sign problem free determinantal quantum
Monte Carlo, at any charge density. For generic charge densities,
$\mathbb{Z}_2$ gauge fluctuations mediate pairing and the ground state is a
gapped superfluid. Superfluidity also appears in the confined phase. This is
reminiscent of the BCS-BEC crossover, except that a true zero temperature
transition occurs here, with the maximum $T_c$ achieved near the transition. At
half-filling also one obtains a large Fermi surface which is gapped at zero
temperature. However, on increasing fermion hopping a $\pi$-flux phase is
spontaneously generated, with emergent Dirac fermions that are stable against
pairing. In contrast to a Fermi liquid of electrons, the change in Fermi
surface volumes of the $\mathbb{Z}_2$ fermions occurs without the breaking of
translation symmetry. Unexpectedly, the numerics indicate a single continuous
transition between the deconfined Dirac phase and the confined superfluid, in
contrast to the naive expectation of a split transition, where a gap to
fermions precedes confinement.


title:
MUSE searches for galaxies near very metal-poor gas clouds at z~3: new
  constraints for cold accretion models

abstract:
  We report on the search for galaxies in the proximity of two very metal-poor
gas clouds at z~3 towards the quasar Q0956+122. With a 5-hour MUSE integration
in a ~500x500 kpc^2 region centred at the quasar position, we achieve a >80%
complete spectroscopic survey of continuum-detected galaxies with m<25 mag and
Ly{\alpha} emitters with luminosity L>3e41 erg/s. We do not identify galaxies
at the redshift of a z~3.2 Lyman limit system (LLS) with log Z/Zsun = -3.35 +/-
0.05, placing this gas cloud in the intergalactic medium or circumgalactic
medium of a galaxy below our sensitivity limits. Conversely, we detect five
Ly{\alpha} emitters at the redshift of a pristine z~3.1 LLS with log Z/Zsun <
-3.8, while ~0.4 sources were expected given the z~3 Ly{\alpha} luminosity
function. Both this high detection rate and the fact that at least three
emitters appear aligned in projection with the LLS suggest that this pristine
cloud is tracing a gas filament that is feeding one or multiple galaxies. Our
observations uncover two different environments for metal-poor LLSs, implying a
complex link between these absorbers and galaxy halos, which ongoing MUSE
surveys will soon explore in detail. Moreover, in agreement with recent MUSE
observations, we detected a ~90 kpc Ly{\alpha} nebula at the quasar redshift
and three Ly{\alpha} emitters reminiscent of a "dark galaxy" population.


title:
Shear viscosity at the Ising-nematic quantum critical point in two
  dimensional metals

abstract:
  In an isotropic strongly interacting quantum liquid without quasiparticles,
general scaling arguments imply that the dimensionless ratio $(k_B /\hbar)\,
\eta/s$, where $\eta$ is the shear viscosity and $s$ is the entropy density, is
a universal number. We compute the shear viscosity of the Ising-nematic
critical point of metals in spatial dimension $d=2$ by an expansion below
$d=5/2$. The anisotropy associated with directions parallel and normal to the
Fermi surface leads to a violation of the scaling expectations: $\eta$ scales
in the same manner as a chiral conductivity, and the ratio $\eta/s$ diverges at
low temperature ($T$) as $T^{-2/z}$, where $z$ is the dynamic critical exponent
for fermionic excitations dispersing normal to the Fermi surface.


title:
Tie-breaker: Using language models to quantify gender bias in sports
  journalism

abstract:
  Gender bias is an increasingly important issue in sports journalism. In this
work, we propose a language-model-based approach to quantify differences in
questions posed to female vs. male athletes, and apply it to tennis post-match
interviews. We find that journalists ask male players questions that are
generally more focused on the game when compared with the questions they ask
their female counterparts. We also provide a fine-grained analysis of the
extent to which the salience of this bias depends on various factors, such as
question type, game outcome or player rank.


title:
Many-body topological invariants for fermionic symmetry-protected
  topological phases

abstract:
  We define and compute many-body topological invariants of interacting
fermionic symmetry-protected topological phases, protected by an
orientation-reversing symmetry, such as time-reversal or reflection symmetry.
The topological invariants are given by partition functions obtained by a path
integral on unoriented spacetime which, as we show, can be computed for a given
ground state wave function by considering a non-local operation, "partial"
reflection or transpose. As an application of our scheme, we study the
$\mathbb{Z}_8$ and $\mathbb{Z}_{16}$ classification of topological
superconductors in one and three dimensions.


title:
Shift-symmetries and gauge coupling functions in orientifolds and
  F-theory

abstract:
  We investigate the field dependence of the gauge coupling functions of
four-dimensional Type IIB orientifold and F-theory compactifications with
space-time filling seven-branes. In particular, we analyze the constraints
imposed by holomorphicity and covariance under shift-symmetries of the bulk and
brane axions. This requires introducing quantum corrections that necessarily
contain Riemann theta functions on the complex torus spanned by the D7-brane
Wilson line moduli. Our findings hint towards a new underlying geometric
structure for gauge coupling functions in string compactifications. We
generalize this discussion to a genuine F-theory compactification on an
elliptically fibered Calabi-Yau fourfold. We perform the first general
dimensional reduction of eleven-dimensional supergravity and dualization to the
F-theory frame. The resulting effective action is compared with the circle
reduction of a four-dimensional N=1 supergravity theory. The F-theory geometry
elegantly unifies bulk and brane degrees of freedom and allows us to infer
non-trivial results about holomorphicity and shift-symmetries. For instance, we
gain new insight into kinetic mixing of bulk and brane gauge fields.


title:
Bethe-Heitler cascades as a plausible origin of hard spectra in distant
  TeV blazars

abstract:
  Context. Very high-energy (VHE) $\gamma$-ray measurements of distant TeV
blazars can be nicely explained by TeV spectra induced by ultra high-energy
cosmic rays.
  Aims. We develop a model for a plausible origin of hard spectra in distant
TeV blazars. Methods. In the model, the TeV emission in distant TeV blazars is
dominated by two mixed components. The first is the internal component with the
photon energy around 1 TeV produced by inverse Compton scattering of the
relativistic electrons on the synchrotron photons (SSC) with a correction for
extragalactic background light absorbtion and the other is the external
component with the photon energy more than 1 TeV produced by the cascade
emission from high-energy protons propagating through intergalactic space.
  Results. Assuming suitable model parameters, we apply the model to observed
spectra of distant TeV blazars of 1ES 0229+200. Our results show that 1) the
observed spectrum properties of 1ES 0229+200, especially the TeV $\gamma$-ray
tail of the observed spectra, could be reproduced in our model and 2) an
expected TeV $\gamma$-ray spectrum with photon energy $>$1 TeV of 1ES 0229+200
should be comparable with the 50-hour sensitivity goal of the Cherenkov
Telescope Array (CTA) and the differential sensitivity curve for the one-year
observation with the Large High Altitude Air Shower Observatory (LHAASO).
  Conclusions. We argue that strong evidence for the Bethe-Heitler cascades
along the line of sight as a plausible origin of hard spectra in distant TeV
blazars could be obtained from VHE observations with CTA, LHAASO, HAWC, and
HiSCORE.


title: Half-Metallic Superconducting Triplet Spin Valve

abstract:
  We theoretically study a finite size $SF_1NF_2$ spin valve, where a normal
metal ($N$) insert separates a thin standard ferromagnet ($F_1$) and a thick
half-metallic ferromagnet ($F_2$). For sufficiently thin superconductor ($S$)
widths close to the coherence length $\xi_0$, we find that changes to the
relative magnetization orientations in the ferromagnets can result in
substantial variations in the transition temperature $T_c$, consistent with
experiment [Singh et al., Phys. Rev. X 5, 021019 (2015)]. Our results
demonstrate that, in good agreement with the experiment, the variations are
largest in the case where $F_2$ is in a half-metallic phase and thus supports
only one spin direction. To pinpoint the origins of this strong spin-valve
effect, both the equal-spin $f_1$ and opposite-spin $f_0$ triplet correlations
are calculated using a self-consistent microscopic technique. We find that when
the magnetization in $F_1$ is tilted slightly out-of-plane, the $f_1$ component
can be the dominant triplet component in the superconductor. The coupling
between the two ferromagnets is discussed in terms of the underlying spin
currents present in the system. We go further and show that the zero energy
peaks of the local density of states probed on the $S$ side of the valve can be
another signature of the presence of superconducting triplet correlations. Our
findings reveal that for sufficiently thin $S$ layers, the zero energy peak at
the $S$ side can be larger than its counterpart in the $F_2$ side.


title:
The primordial deuterium abundance of the most metal-poor damped
  Lyman-alpha system

abstract:
  We report the discovery and analysis of the most metal-poor damped
Lyman-alpha (DLA) system currently known, which also displays the Lyman series
absorption lines of neutral deuterium. The average [O/H] abundance of this
system is [O/H] = -2.804 +/- 0.015, which includes an absorption component with
[O/H] = -3.07 +/- 0.03. Despite the unfortunate blending of many weak D I
absorption lines, we report a precise measurement of the deuterium abundance of
this system. Using the six highest quality and self-consistently analyzed
measures of D/H in DLAs, we report tentative evidence for a subtle decrease of
D/H with increasing metallicity. This trend must be confirmed with future high
precision D/H measurements spanning a range of metallicity. A weighted mean of
these six independent measures provides our best estimate of the primordial
abundance of deuterium, 10^5 (D/H)_P = 2.547 +/- 0.033 (log_10 (D/H)_P =
-4.5940 +/- 0.0056). We perform a series of detailed Monte Carlo calculations
of Big Bang nucleosynthesis (BBN) that incorporate the latest determinations of
several key nuclear cross sections, and propagate their associated uncertainty.
Combining our measurement of (D/H)_P with these BBN calculations yields an
estimate of the cosmic baryon density, 100 Omega_B,0 h^2(BBN) = 2.156 +/-
0.020, if we adopt the most recent theoretical determination of the
d(p,gamma)3He reaction rate. This measure of Omega_B,0 h^2 differs by ~2.3
sigma from the Standard Model value estimated from the Planck observations of
the cosmic microwave background. Using instead a d(p,gamma)3He reaction rate
that is based on the best available experimental cross section data, we
estimate 100 Omega_B,0 h^2(BBN) = 2.260 +/- 0.034, which is in somewhat better
agreement with the Planck value. Forthcoming measurements of the crucial
d(p,gamma)3He cross section may shed further light on this discrepancy.


title: The Ryu-Takayanagi Formula from Quantum Error Correction

abstract:
  I argue that a version of the quantum-corrected Ryu-Takayanagi formula holds
in any quantum error-correcting code. I present this result as a series of
theorems of increasing generality, with the final statement expressed in the
language of operator-algebra quantum error correction. In AdS/CFT this gives a
"purely boundary" interpretation of the formula. I also extend a recent
theorem, which established entanglement-wedge reconstruction in AdS/CFT, when
interpreted as a subsystem code, to the more general, and I argue more
physical, case of subalgebra codes. For completeness, I include a
self-contained presentation of the theory of von Neumann algebras on
finite-dimensional Hilbert spaces, as well as the algebraic definition of
entropy. The results confirm a close relationship between bulk gauge
transformations, edge-modes/soft-hair on black holes, and the Ryu-Takayanagi
formula. They also suggest a new perspective on the homology constraint, which
basically is to get rid of it in a way that preserves the validity of the
formula, but which removes any tension with the linearity of quantum mechanics.
Moreover they suggest a boundary interpretation of the "bit threads" recently
introduced by Freedman and Headrick.


title: Topological Quantum Matter with Ultracold Gases in Optical Lattices

abstract:
  Since the discovery of topological insulators, many topological phases have
been predicted and realized in a range of different systems, providing both
fascinating physics and exciting opportunities for devices. And although new
materials are being developed and explored all the time, the prospects for
probing exotic topological phases would be greatly enhanced if they could be
realized in systems that were easily tuned. The flexibility offered by
ultracold atoms could provide such a platform. Here, we review the tools
available for creating topological states using ultracold atoms in optical
lattices, give an overview of the theoretical and experimental advances and
provide an outlook towards realizing strongly correlated topological phases.


title:
A broadband X-ray spectral study of the intermediate-mass black hole
  candidate M82 X-1 with NuSTAR, Chandra and Swift

abstract:
  M82 X-1 is one of the brightest ultraluminous X-ray sources (ULXs) known,
which, assuming Eddington-limited accretion and other considerations, makes it
one of the best intermediate-mass black hole (IMBH) candidates. However, the
ULX may still be explained by super-Eddington accretion onto a stellar-remnant
black hole. We present simultaneous NuSTAR, Chandra and Swift/XRT observations
during the peak of a flaring episode with the aim of modeling the emission of
M82 X-1 and yielding insights into its nature. We find that thin-accretion disk
models all require accretion rates at or above the Eddington limit in order to
reproduce the spectral shape, given a range of black hole masses and spins.
Since at these high Eddington ratios the thin-disk model breaks down due to
radial advection in the disk, we discard the results of the thin-disk models as
unphysical. We find that the temperature profile as a function of disk radius
($T(r)\propto r^{-p}$) is significantly flatter ($p=0.55^{+ 0.07}_{- 0.04}$)
than expected for a standard thin disk ($p=0.75$). A flatter profile is instead
characteristic of a slim disk which is highly suggestive of super-Eddington
accretion. Furthermore, radiation hydrodynamical simulations of super-Eddington
accretion have shown that the predicted spectra of these systems are very
similar to what we observe for M82 X-1. We therefore conclude that M82 X-1 is a
super-Eddington accretor. Our mass estimates inferred from the inner disk
radius imply a stellar-remnant black hole ($M_{\rm BH}=26^{+9}_{-6} M_{\odot}$)
when assuming zero spin, or an IMBH ($M_{\rm BH}=125^{+45}_{-30} M_{\odot}$)
when assuming maximal spin.


title:
The SCUBA-2 Cosmology Legacy Survey: 850um maps, catalogues and number
  counts

abstract:
  We present a catalogue of nearly 3,000 submillimetre sources detected at
850um over ~5 square degrees surveyed as part of the James Clerk Maxwell
Telescope (JCMT) SCUBA-2 Cosmology Legacy Survey (S2CLS). This is the largest
survey of its kind at 850um, probing a meaningful cosmic volume at the peak of
star formation activity and increasing the sample size of submillimetre
galaxies selected at 850um by an order of magnitude. We describe the wide 850um
survey component of S2CLS, which covers the key extragalactic survey fields:
UKIDSS-UDS, COSMOS, Akari-NEP, Extended Groth Strip, Lockman Hole North, SSA22
and GOODS-North. The average 1-sigma depth of S2CLS is 1.2 mJy/beam,
approaching the SCUBA-2 850um confusion limit, which we determine to be ~0.8
mJy/beam. We measure the single dish 850um number counts to unprecedented
accuracy, reducing the Poisson errors on the differential counts to
approximately 4% at S_850~3mJy. With several independent fields, we investigate
field-to-field variance, finding that the number counts on 0.5-1 degree scales
are generally within 50% of the S2CLS mean for S_850>3mJy, with scatter
consistent with the Poisson and estimated cosmic variance uncertainties,
although there is a marginal (2-sigma) density enhancement in the GOODS-North
field. The observed number counts are in reasonable agreement with recent
phenomenological and semi-analytic models. Finally, the large solid angle of
S2CLS allows us to measure the bright-end counts: at S_850>10mJy there are
approximately ten sources per square degree, and we detect the distinctive
up-turn in the number counts indicative of the detection of local sources of
850um emission and strongly lensed high-redshift galaxies. Here we describe the
data collection and reduction procedures and present calibrated maps and a
catalogue of sources; these are made publicly available.


title: Bilinear condensate in three-dimensional large-$N_c$ QCD

abstract:
  We find clear numerical evidence for a bilinear condensate in
three-dimensional QCD in the 't Hooft limit. We use a non-chiral random matrix
model to extract the value of the condensate $\Sigma$ from the low-lying
eigenvalues of the massless anti-Hermitian overlap Dirac operator. We estimate
$\Sigma/\lambda^2 = 0.0042 \pm 0.0004$ in units of the physical 't Hooft
coupling.


title: Predictions of the atmospheric composition of GJ 1132b

abstract:
  GJ 1132 b is a nearby Earth-sized exoplanet transiting an M dwarf, and is
amongst the most highly characterizable small exoplanets currently known. In
this paper we study the interaction of a magma ocean with a water-rich
atmosphere on GJ 1132b and determine that it must have begun with more than 5
wt% initial water in order to still retain a water-based atmosphere. We also
determine the amount of O2 that can build up in the atmosphere as a result of
hydrogen dissociation and loss. We find that the magma ocean absorbs at most
~10% of the O2 produced, whereas more than 90% is lost to space through
hydrodynamic drag. The most common outcome for GJ 1132 b from our simulations
is a tenuous atmosphere dominated by O2, although for very large initial water
abundances atmospheres with several thousands of bars of O2 are possible. A
substantial steam envelope would indicate either the existence of an earlier H2
envelope or low XUV flux over the system's lifetime. A steam atmosphere would
also imply the continued existence of a magma ocean on GJ 1132 b. Further
modeling is needed to study the evolution of CO2 or N2-rich atmospheres on GJ
1132 b.


title:
External Compton Scattering in Blazar Jets and the Location of the
  Gamma-Ray Emitting Region

abstract:
  I study the location of the $\gamma$-ray emission in blazar jets by creating
a Compton-scattering approximation valid for all anisotropic radiation fields
in the Thomson through Klein-Nishina regimes, which is highly accurate and can
speed up numerical calculations by up to a factor $\sim10$. I apply this
approximation to synchrotron self-Compton, and external Compton-scattering of
photons from the accretion disk, broad-line region (BLR), and dust torus. I use
a stratified BLR model and include detailed Compton-scattering calculations of
a spherical and flattened BLR. I create two dust torus models, one where the
torus is an annulus, and one where it is an extended disk. I present detailed
calculations of the photoabsorption optical depth using my detailed BLR and
dust torus models, including the full angle dependence. I apply these
calculations to the emission from a relativistically moving blob traveling
through these radiation fields. The ratio of $\gamma$-ray to optical flux
produces a predictable pattern that could help locate the $\gamma$-ray emission
region. I show that the bright flare from 3C 454.3 in 2010 November detected by
the Fermi Large Area Telescope is unlikely to originate from a single blob
inside the BLR since it moves outside the BLR in a time shorter than the flare
duration, although emission by multiple blobs inside the BLR is possible; and
$\gamma$-rays are unlikely to originate from outside the BLR from scattering of
photons from an extended dust torus, since then the cooling timescale would be
too long to explain the observed short variability.


title: Smooth horizonless geometries deep inside the black-hole regime

abstract:
  We construct the first family of horizonless supergravity solutions that have
the same mass, charges and angular momenta as general supersymmetric rotating
D1-D5-P black holes in five dimensions. This family includes solutions with
arbitrarily small angular momenta, deep within the regime of quantum numbers
and couplings for which a large classical black hole exists. These geometries
are well-approximated by the black-hole solution, and in particular exhibit the
same near-horizon throat. Deep in this throat, the black-hole singularity is
resolved into a smooth cap. We also identify the holographically-dual states in
the N=(4,4) D1-D5 orbifold CFT. Our solutions are among the states counted by
the CFT elliptic genus, and provide examples of smooth microstate geometries
within the ensemble of supersymmetric black-hole microstates.


title: The Evolution of Galaxy Number Density at z < 8 and its Implications

abstract:
  The evolution of the number density of galaxies in the universe, and thus
also the total number of galaxies, is a fundamental question with implications
for a host of astrophysical problems including galaxy evolution and cosmology.
However there has never been a detailed study of this important measurement,
nor a clear path to answer it. To address this we use observed galaxy stellar
mass functions up to $z\sim8$ to determine how the number densities of galaxies
changes as a function of time and mass limit. We show that the increase in the
total number density of galaxies ($\phi_{\rm T}$), more massive than M$_{*} =
10^{6}$ M_0, decreases as $\phi_{\rm T} \sim t^{-1}$, where $t$ is the age of
the universe. We further show that this evolution turns-over and rather
increases with time at higher mass lower limits of M$_{*}>10^{7}$ M_0. By using
the M$_{*}=10^{6}$ M_0 lower limit we further show that the total number of
galaxies in the universe up to $z = 8$ is $2.0^{+0.7}_{-0.6} \times 10^{12}$
(two trillion), almost a factor of ten higher than would be seen in an all sky
survey at Hubble Ultra-Deep Field depth. We discuss the implications for these
results for galaxy evolution, as well as compare our results with the latest
models of galaxy formation. These results also reveal that the cosmic
background light in the optical and near-infrared likely arise from these
unobserved faint galaxies. We also show how these results solve the question of
why the sky at night is dark, otherwise known as Olbers' paradox.


title:
Finite-temperature modification of heavy particle decay and dark matter
  annihilation

abstract:
  We apply the operator product expansion (OPE) technique to the decay and
annihilation of heavy particles in a thermal medium with temperature below the
heavy particle mass, m_chi. This allows us to explain two interesting
observations made before: a) that the leading thermal correction to the decay
width of a charged particle is the same multiplicative factor of the
zero-temperature width for a two-body decay and muon decay, and b) that the
leading thermal correction to fermionic dark matter annihilation arises only at
order T^4/m_chi^4. The OPE further considerably simplifies the computation and
factorizes it into model-independent matrix elements in the thermal background,
and short-distance coefficients to be computed in zero-temperature field
theory.


title: Thermal diode made by nematic liquid crystal

abstract:
  This work investigates how a thermal diode can be designed from a nematic
liquid crystal confined inside a cylindrical capillary. In the case of
homeotropic anchoring, a defect structure called escaped radial disclination
arises. The asymmetry of such structure causes thermal rectification rates up
to 3.5\% at room temperature, comparable to thermal diodes made from carbon
nanotubes. Sensitivity of the system with respect the heat power supply, the
geometry of the capillary tube and the molecular anchoring angle is also
discussed.


title: A simple fermionic model of deconfined phases and phase transitions

abstract:
  Using Quantum Monte Carlo simulations, we study a series of models of
fermions coupled to quantum Ising spins on a square lattice with $N$ flavors of
fermions per site for $N=1,2$ and $3$. The models have an extensive number of
conserved quantities but are not integrable, and have rather rich phase
diagrams consisting of several exotic phases and phase transitions that lie
beyond Landau-Ginzburg paradigm. In particular, one of the prominent phase for
$N>1$ corresponds to $2N$ gapless Dirac fermions coupled to an emergent
$\mathbb{Z}_2$ gauge field in its deconfined phase. However, unlike a
conventional $\mathbb{Z}_2$ gauge theory, we do not impose the `Gauss's Law' by
hand and instead, it emerges due to spontaneous symmetry breaking.
Correspondingly, unlike a conventional $\mathbb{Z}_2$ gauge theory in two
spatial dimensions, our models have a finite temperature phase transition
associated with the melting of the order parameter that dynamically imposes the
Gauss's law constraint at zero temperature. By tuning a parameter, the
deconfined phase undergoes a transition into a short range entangled phase,
which corresponds to N\'eel/Superconductor for $N=2$ and a Valence Bond Solid
for $N=3$. Furthermore, for $N=3$, the Valence Bond Solid further undergoes a
transition to a N\'eel phase consistent with the deconfined quantum critical
phenomenon studied earlier in the context of quantum magnets.


title: On four-derivative terms in IIB Calabi-Yau orientifold reductions

abstract:
  We perform a Kaluza-Klein reduction of IIB supergravity including purely
gravitational $\alpha '^3$-corrections on a Calabi-Yau threefold, and perform
the orientifold projection accounting for the presence of $O3/O7$-planes. We
consider infinitesimal K\"{a}hler deformations of the Calabi-Yau background and
derive the complete set of four-derivative couplings quadratic in these
fluctuations coupled to gravity. In particular, we find four-derivative
couplings of the K\"{a}hler moduli fields in the four-dimensional effective
supergravity theory, which are referred to as friction couplings in the context
of inflation.


title: A simple multiforce layout for multiplex networks

abstract:
  We introduce multiforce, a force-directed layout for multiplex networks,
where the nodes of the network are organized into multiple layers and both
in-layer and inter-layer relationships among nodes are used to compute node
coordinates. The proposed approach generalizes existing work, providing a range
of intermediate layouts in-between the ones produced by known methods. Our
experiments on real data show that multiforce can keep nodes well aligned
across different layers without significantly affecting their internal layouts
when the layers have similar or compatible topologies. As a consequence,
multiforce enriches the benefits of force-directed layouts by also supporting
the identification of topological correspondences between layers.


title:
Star formation and AGN activity in the most luminous LINERs in the local
  universe

abstract:
  This work presents the properties of 42 objects in the group of the most
luminous, highest star formation rate LINERs at z = 0.04 - 0.11. We obtained
long-slit spectroscopy of the nuclear regions for all sources, and FIR data
(Herschel and IRAS) for 13 of them. We measured emission line intensities,
extinction, stellar populations, stellar masses, ages, AGN luminosities, and
star-formation rates. We find considerable differences from other low-redshift
LINERs, in terms of extinction, and general similarity to star forming (SF)
galaxies. We confirm the existence of such luminous LINERs in the local
universe, after being previously detected at z ~ 0.3 by Tommasin et al. (2012).
The median stellar mass of these LINERs corresponds to 6 - 7 $\times$
10$^{10}$M$_{\odot}$ which was found in previous work to correspond to the peak
of relative growth rate of stellar populations and therefore for the highest
SFRs. Other LINERs although showing similar AGN luminosities have lower SFR. We
find that most of these sources have LAGN ~ LSF suggesting co-evolution of
black hole and stellar mass. In general among local LINERs being on the
main-sequence of SF galaxies is related to their AGN luminosity.


title: Chiral Gravitational Waves from Chiral Fermions

abstract:
  We report on a new mechanism that leads to the generation of primordial
chiral gravitational waves, and hence, the violation of the parity symmetry in
the Universe. We show that nonperturbative production of fermions with a
definite helicity is accompanied by the generation of chiral gravitational
waves. This is a generic and model-independent phenomenon that can occur during
inflation, reheating and radiation eras, and can leave imprints in the cosmic
microwave background polarization and may be observed in future ground- and
space-based interferometers. We also discuss a specific model where chiral
gravitational waves are generated via the production of light chiral fermions
during pseudoscalar inflation.


title:
A nanoflare based cellular automaton model and the observed properties
  of the coronal plasma

abstract:
  We use the cellular automaton model described in L\'opez Fuentes \& Klimchuk
(2015, ApJ, 799, 128) to study the evolution of coronal loop plasmas. The
model, based on the idea of a critical misalignment angle in tangled magnetic
fields, produces nanoflares of varying frequency with respect to the plasma
cooling time. We compare the results of the model with active region (AR)
observations obtained with the Hinode/XRT and SDO/AIA instruments. The
comparison is based on the statistical properties of synthetic and observed
loop lightcurves. Our results show that the model reproduces the main
observational characteristics of the evolution of the plasma in AR coronal
loops. The typical intensity fluctuations have an amplitude of 10 to 15\% both
for the model and the observations. The sign of the skewness of the intensity
distributions indicates the presence of cooling plasma in the loops. We also
study the emission measure (EM) distribution predicted by the model and obtain
slopes in log(EM) versus log(T) between 2.7 and 4.3, in agreement with
published observational values.


title: Graph Isomorphism Restricted by Lists

abstract:
  The complexity of graph isomorphism (GraphIso) is a famous unresolved problem
in theoretical computer science. For graphs $G$ and $H$, it asks whether they
are the same up to a relabeling of vertices. In 1981, Lubiw proved that list
restricted graph isomorphism (ListIso) is NP-complete: for each $u \in V(G)$,
we are given a list ${\mathfrak L}(u) \subseteq V(H)$ of possible images of
$u$. After 35 years, we revive the study of this problem and consider which
results for GraphIso translate to ListIso.
  We prove the following: 1) When GraphIso is GI-complete for a class of
graphs, it translates into NP-completeness of ListIso. 2) Combinatorial
algorithms for GraphIso translate into algorithms for ListIso: for trees,
planar graphs, interval graphs, circle graphs, permutation graphs, bounded
genus graphs, and bounded treewidth graphs. 3) Algorithms based on group theory
do not translate: ListIso remains NP-complete for cubic colored graphs with
sizes of color classes bounded by 8.
  Also, ListIso allows to classify results for the graph isomorphism problem.
Some algorithms are robust and translate to ListIso. A fundamental problem is
to construct a combinatorial polynomial-time algorithm for cubic graph
isomorphism, avoiding group theory. By the 3rd result, ListIso is NP-hard for
them, so no robust algorithm for cubic graph isomorphism exists, unless P = NP.


title: Instability of mass transfer in a planet-star system

abstract:
  We show that the angular momentum exchange mechanism governing the evolution
of mass transferring binary stars does not apply to Roche-lobe filling planets,
because most of the angular momentum of the mass transferring stream is
absorbed by the host star. Apart from a correction for the difference in
specific angular momentum of the stream and the centre of mass of the planet,
the orbit does not expand much on Roche-lobe overflow. We explore the
conditions for dynamically unstable Roche-lobe overflow as a function of planet
mass and mass and radius (age) of host star and equation of state of planet.
For a Sun-like host, gas giant planets in a range of mass and entropy can
undergo dynamical mass transfer. Examples of the evolution of the mass transfer
process are given. Dynamic mass transfer of rocky planets depend somewhat
sensitively on equation of state used. Silicate planets in the range $1
M_{\oplus} <M_{\mathrm{p}} < 10 M_{\oplus} $ typically go through a phase of
dynamical mass transfer before settling to slow overflow when their mass drops
to less than $1 M_{\oplus}$.


title: Dynamical renormalization group approach to the spin-boson model

abstract:
  We develop a semi-analytical approach beyond the Born-Markov approximation to
study the quench dynamics of the spin-boson model in the strong-coupling regime
($\alpha\leq1/2$) for the Ohmic bath. The basic idea in our approach is to
write an effective time-dependent model for the dynamics of the system coupled
to the bosonic bath after integrating out high-frequency bath modes. By
applying this procedure to the Heisenberg equations of motion, we derive a set
of flow equations for the system parameters as a function of time. The final
flow equations look similar to those of the equilibrium renormalization-group
theory; however, in our derivation the scaling parameter is set by the real
time. We solve the equations of motion with time-dependent renormalized
parameters and show that the resulting dynamics is in decent agreement with the
exact NRG calculations as well as the non-interacting blip approximation that
is a well-known good solution in this limit.


title: Multiple scattering dynamics of fermions at an isolated p-wave resonance

abstract:
  The wavefunction for indistinguishable fermions is anti-symmetric under
particle exchange, which directly leads to the Pauli exclusion principle, and
hence underlies the structure of atoms and the properties of almost all
materials. In the dynamics of collisions between two indistinguishable fermions
this requirement strictly prohibits scattering into 90 degree angles. Here we
experimentally investigate the collisions of ultracold clouds fermionic
$\rm^{40}K$ atoms by directly measuring scattering distributions. With
increasing collision energy we identify the Wigner threshold for p-wave
scattering with its tell-tale dumb-bell shape and no $90^\circ$ yield. Above
this threshold effects of multiple scattering become manifest as deviations
from the underlying binary p-wave shape, adding particles either isotropically
or axially. A shape resonance for $\rm^{40}K$ facilitates the separate
observation of these two processes. The isotropically enhanced multiple
scattering mode is a generic p-wave threshold phenomenon, while the axially
enhanced mode should occur in any colliding particle system with an elastic
scattering resonance.


title: Development of Graphical User Interface For Microwave Filter Design

abstract:
  This research project aims at developing a low-cost, time-effective and a
stand-alone graphical user interface (GUI) that will be used to design
microwave filters. Throughout the projects, the main theory behind the
technology of microwave filters, their generalized mathematical equations and
the analysis of their different circuit topologies have been reviewed. This
review helps to extract the necessary information needed for the design of
microwave filters. Besides, the guiding principles and the underlying
engineering factors for a successful and information-oriented GUI were also
highlighted. To carry out the project, the High-Level GUI Development
Environment (GUIDE) together with a structured programming approach have been
used to design the GUI, and to program its related functionalities. The
frequency responses are generated by using the generalized equation of each
filter class and type; and by using their different circuit topologies (Shunt
or Series topology). The GUI can also provide reactive element values from
given specification. Moreover, the features for the design of ultra-wideband
(UWB) band-pass filter, capacitively coupled and combline filter are also
incorporated into the stand-alone application. The finalized prototype will
serve both industries and educational institutions.


title: Nonlinear Electromagnetic Fields As a Source of Universe Acceleration

abstract:
  A model of nonlinear electromagnetic fields with a dimensional parameter
$\beta$ is proposed. From PVLAS experiment the bound on the parameter $\beta$
was obtained. Electromagnetic fields are coupled with the gravitation field and
we show that the universe accelerates due to nonlinear electromagnetic fields.
The magnetic universe is considered and the stochastic magnetic field is a
background. After inflation the universe decelerates and approaches to the
radiation era. The range of the scale factor, when the causality of the model
and a classical stability take place, was obtained. The spectral index, the
tensor-to-scalar ratio, and the running of the spectral index were estimated
which are in approximate agreement with the PLANCK, WMAP, and BICEP2 data.


title:
Measurement of Target and Double-spin Asymmetries for the $\vec e\vec
  p\to e\pi^+ (n)$ Reaction in the Nucleon Resonance Region at Low $Q^2$

abstract:
  We report measurements of target- and double-spin asymmetries for the
exclusive channel $\vec e\vec p\to e\pi^+ (n)$ in the nucleon resonance region
at Jefferson Lab using the CEBAF Large Acceptance Spectrometer (CLAS). These
asymmetries were extracted from data obtained using a longitudinally polarized
NH$_3$ target and a longitudinally polarized electron beam with energies 1.1,
1.3, 2.0, 2.3 and 3.0 GeV. The new results are consistent with previous CLAS
publications but are extended to a low $Q^2$ range from $0.0065$ to $0.35$
(GeV$/c$)$^2$. The $Q^2$ access was made possible by a custom-built Cherenkov
detector that allowed the detection of electrons for scattering angles as low
as $6^\circ$. These results are compared with the unitary isobar models JANR
and MAID, the partial-wave analysis prediction from SAID and the dynamic model
DMT. In many kinematic regions our results, in particular results on the target
asymmetry, help to constrain the polarization-dependent components of these
models.


title: Microfocus small-angle X-ray scattering at SSRF BL16B1

abstract:
  Offering high-brilliance X-ray beams on micrometer length scales, the
microfocus-SAXS at SSRF BL16B1 was established with a KB mirror system for
studying small sample volumes, or probing micro-scopic morphologies. The SAXS
minimum q value was 0.1nm-1 with a flux of 1.5 * 10^10 photons/s. Two
position-resolved scanning experimental methods were combined with
microfocus-SAXS that include STXM and CT. To improve the significant smearing
effect in the horizontal direction, an effective and easy-to-use desmearing
procedure for two-dimensional SAXS pattern based on the blind deconvolution was
developed and the deblurring results demonstrated the good restoration effect
for the defocus image. Finally, a bamboo sample was selected for SAXS-CT
experiment which illustrated the performance of the microfocus-SAXS method.


title:
The Electrostatic Screening Length in Concentrated Electrolytes
  Increases with Concentration

abstract:
  According to classical electrolyte theories interactions in dilute (low ion
density) electrolytes decay exponentially with distance, with the Debye
screening length the characteristic length-scale. This decay length decreases
monotonically with increasing ion concentration, due to effective screening of
charges over short distances. Thus within the Debye model no long-range forces
are expected in concentrated electrolytes. Here we reveal, using experimental
detection of the interaction between two planar charged surfaces across a wide
range of electrolytes, that beyond the dilute (Debye-Huuckel) regime the
screening length increases with increasing concentration. The screening lengths
for all electrolytes studied - including aqueous NaCl solutions, ionic liquids
diluted with propylene carbonate, and pure ionic liquids - collapse onto a
single curve when scaled by the dielectric constant. This non-monotonic
variation of the screening length with concentration, and its generality across
ionic liquids and aqueous salt solutions, demonstrates an important
characteristic of concentrated electrolytes of substantial relevance from
biology to energy storage.


title: An experimental review on heavy flavor $v_{2}$ in heavy-ion collision

abstract:
  For over a decade now, the primary purpose of relativistic heavy-ion
collisions at the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron
Collider (LHC) has been to study the properties of QCD matter under extreme
conditions -high temperature and high density. The heavy-ion experiments at
both RHIC and LHC have recorded a wealth of data in p+p, p+Pb, d+Au, Cu+Cu,
Cu+Au, Au+Au, Pb+Pb and U+U collisions at energies ranging from $\sqrt{s_{NN}}$
= 7.7 GeV to 7 TeV. Heavy quarks are considered good probe to study the QCD
matter created in relativistic collisions due to their very large mass and
other unique properties. A precise measurement of various properties of heavy
flavor hadrons provides an insight into the fundamental properties of the hot
and dense medium created in these nuclei-nuclei collisions, such as transport
coefficient and thermalization and hadronization mechanisms. The main focus of
this paper is to present a review on the measurements of azimuthal anisotropy
of heavy flavor hadrons and to outline the scientific opportunities in this
sector due to future detector upgrade. We will mainly discuss the elliptic flow
of open charmed meson ($D$-meson), $J/\psi$ and leptons from heavy flavor decay
at RHIC and LHC energy.


title:
Interacting dark matter and q-deformed dark energy non-minimally coupled
  to gravity

abstract:
  In this paper, we propose a new approach to study the dark sector of the
universe by considering the dark energy as emerging a q-deformed bosonic scalar
field which is not only interacting with the dark matter, but also
non-minimally coupled to gravity, in the framework of standard Einsteinian
gravity. In order to analyze the dynamic of the system, we first give the
quantum field theoretical description of the q-deformed scalar field dark
energy, then construct the action and the dynamical structure of these
interacting and non-minimally coupled dark sector. As a second issue, we
perform the phase space analysis of the model to check the reliability of our
proposal by searching the stable attractor solutions implying the late-time
accelerating expansion phase of the universe.


title: The interaction of a magnetohydrodynamical shock with a filament

abstract:
  We present 3D magnetohydrodynamic numerical simulations of the adiabatic
interaction of a shock with a dense, filamentary cloud. We investigate the
effects of various filament lengths and orientations on the interaction using
different orientations of the magnetic field, and vary the Mach number of the
shock, the density contrast of the filament, and the plasma beta, in order to
determine their effect on the evolution and lifetime of the filament. We find
that in a parallel magnetic field filaments have longer lifetimes if they are
orientated more 'broadside' to the shock front, and that an increase in the
density contrast hastens the destruction of the cloud, in terms of the modified
cloud-crushing time-scale, tcs. The combination of a mild shock and a
perpendicular or oblique field provides the best condition for extending the
life of the filament, with some filaments able to survive almost indefinitely
since they are cocooned by the magnetic field. A high value for the density
contrast does not initiate large turbulent instabilities in either the
perpendicular or oblique field cases but rather draws the filament out into
long tendrils which may eventually fragment. In addition, flux ropes are only
formed in parallel magnetic fields. The length of the filament is, however, not
as important for the evolution and destruction of a filament.


title:
Multicritical behavior of the two-dimensional transverse Ising
  metamagnet in a longitudinal magnetic field

abstract:
  Magnetic phenomena of the superantiferromagnetic Ising model in both uniform
longitudinal ($H$) and transverse ($\Omega $) magnetic fields are studied by
employing a mean-field variational approach based on Peierls-Bogoliubov
inequality for the free energy. A single-spin cluster is used to get the
approximate thermodynamic properties of the model. The phase diagrams in the
magnetic fields and temperature ($T$) planes, namely, $H-T$ and $\Omega-T$, are
analyzed on an anisotropic square lattice for some values of the ratio
$\alpha=J_{y}/J_{x}$, where $J_x$ and $J_y$ are the exchange interactions along
the $x$ and $y$ directions, respectively. Depending on the range of the
Hamiltonian parameters, one has only second-order transition lines, only
first-order transition lines, or first- and second-order transition lines with
the presence of tricritical points. The corresponding phase diagrams show no
reentrant behavior along the first-order transition lines at low temperatures.
These results are different from those obtained by using Effective Field Theory
with the same cluster size.


title: Two-loop Dirac neutrino mass and WIMP dark matter

abstract:
  We propose a "scotogenic" mechanism relating small neutrino mass and
cosmological dark matter. Neutrinos are Dirac fermions with masses arising only
in two--loop order through the sector responsible for dark matter. Two triality
symmetries ensure both dark matter stability and strict lepton number
conservation at higher orders. A global spontaneously broken U(1) symmetry
leads to a physical $Diracon$ that induces invisible Higgs decays which add up
to the Higgs to dark matter mode. This enhances sensitivities to
spin-independent WIMP dark matter search below $m_h/2$.


title: A simple method to construct Flat Band lattices

abstract:
  We develop a simple and general method to construct arbitrary Flat Band
lattices. We identify the basic ingredients behind zero-dispersion bands and
develop a method to construct extended lattices based on a consecutive
repetition of a given mini-array. The number of degenerated localized states is
defined by the number of connected mini-arrays times the number of modes
preserving the symmetry at a given connector site. In this way, we create one
or more (depending on the lattice geometry) complete degenerated Flat Bands for
quasi-one and two-dimensional systems. We probe our method by studying several
examples, and discuss the effect of additional interactions like anisotropy or
nonlinearity. At the end, we test our method by studying numerically a ribbon
lattice using a continuous description.


title:
Luminosity dependence of the cyclotron line and evidence for the
  accretion regime transition in V 0332+53

abstract:
  We report on the analysis of NuSTAR observations of the Be-transient X-ray
pulsar V 0332+53 during the giant outburst in 2015 and another minor outburst
in 2016. We confirm the cyclotron-line energy-luminosity correlation previously
reported in the source and the line energy decrease during the giant outburst.
Based on 2016 observations, we find that a year later the line energy has
increased again essentially reaching the pre-outburst values. We discuss this
behaviour and conclude that it is likely caused by a change of the emission
region geometry rather than previously suggested accretion-induced decay of the
neutron stars magnetic field. At lower luminosities, we find for the first time
a hint of departure from the anticorrelation of line energy with flux, which we
interpret as a transition from super- to sub-critical accretion associated with
the disappearance of the accretion column. Finally, we confirm and briefly
discuss the orbital modulation observed in the outburst light curve of the
source.


title:
Physics of the fundamental limits of nonlinear optics: A theoretical
  perspective

abstract:
  The theory of the fundamental limits (TFL) of nonlinear optics is a powerful
tool for experimentalists seeking to create molecules and materials with large
responses, and for theorists who are seeking to understand how the basic
elements of quantum theory delineate the boundaries within which these searches
should be conducted. On a practical level, the TFL provides a metric for
measuring the performance or 'goodness' of new molecules, relative to what is
possible. Explorations of large sets of structures within the theory provide
insight into new design rules for creating more active molecules. This article
is a review of the TFL, starting with a history of its development and its
first use to discover that all molecules as of the year 2000 fell a factor of
30 below the limits, and continuing to the present day where the theory
continues to provide research opportunities and challenges. The review focuses
on off-resonant nonlinear optics in order to sharply focus on the key elements
of the TFL, but pointers are provided to the literature for near- and
on-resonance applications.


title: Quantum Computing: Linear Optics Implementations

abstract:
  One of the main problems that optical quantum computing has to overcome is
the efficient construction of two-photon gates. Theoretically these gates can
be realized using Kerr-nonlinearities, but the techniques involved are
experimentally very difficult. We therefore employ linear optics with
projective measurements to generate these non-linearities. The downside is that
the measurement-induced nonlinearities achieved with linear optics are less
versatile and the success rate can be quite low. This project is mainly the
result of a literature study but also a theoretical work on the physics behind
quantum optical multiports which is essential for realizing two-photon gates.
By applying different postcorrection techniques we increase the probability of
success in a modifed non-linear sign shift gate which is foundational for the
two photon controlled-NOT gate. We prove that it's not possible to correct the
states by only using a single beam splitter. We show that it might be possible
to increase the probability of success using a more complex setup with at least
two error-correcting beam splitters.


title:
Weighted BFBT Preconditioner for Stokes Flow Problems with Highly
  Heterogeneous Viscosity

abstract:
  We present a weighted BFBT approximation (w-BFBT) to the inverse Schur
complement of a Stokes system with highly heterogeneous viscosity. When used as
part of a Schur complement-based Stokes preconditioner, we observe robust fast
convergence for Stokes problems with smooth but highly varying (up to 10 orders
of magnitude) viscosities, optimal algorithmic scalability with respect to mesh
refinement, and only a mild dependence on the polynomial order of high-order
finite element discretizations ($Q_k \times P_{k-1}^{disc}$, order $k \ge 2$).
For certain difficult problems, we demonstrate numerically that w-BFBT
significantly improves Stokes solver convergence over the widely used inverse
viscosity-weighted pressure mass matrix approximation of the Schur complement.
In addition, we derive theoretical eigenvalue bounds to prove spectral
equivalence of w-BFBT. Using detailed numerical experiments, we discuss
modifications to w-BFBT at Dirichlet boundaries that decrease the number of
iterations. The overall algorithmic performance of the Stokes solver is
governed by the efficacy of w-BFBT as a Schur complement approximation and, in
addition, by our parallel hybrid spectral-geometric-algebraic multigrid (HMG)
method, which we use to approximate the inverses of the viscous block and
variable-coefficient pressure Poisson operators within w-BFBT. Building on the
scalability of HMG, our Stokes solver achieves a parallel efficiency of 90%
while weak scaling over a more than 600-fold increase from 48 to all 30,000
cores of TACC's Lonestar 5 supercomputer.


title:
Dynamics of Stellar Spin Driven by Planets Undergoing Lidov-Kozai
  Migration: Paths to Spin-Orbit Misalignment

abstract:
  Many exoplanetary systems containing hot Jupiters (HJs) exhibit significant
misalignment between the spin axes of the host stars and the orbital angular
momentum axes of the planets ("spin-orbit misalignment"). High-eccentricity
migration involving Lidov-Kozai oscillations of the planet's orbit induced by a
distant perturber is a possible channel for producing such misaligned HJ
systems. Previous works have shown that the dynamical evolution of the stellar
spin axis during the high-$e$ migration plays a dominant role in generating the
observed spin-orbit misalignment. Numerical studies have also revealed various
patterns of the evolution of the stellar spin axis leading to the final
misalignment. Here we develop an analytic theory to elucidate the evolution of
spin-orbit misalignment during the Lidov-Kozai migration of planets in stellar
binaries. Secular spin-orbit resonances play a key role in the misalignment
evolution. We include the effects of short-range forces and tidal dissipation,
and categorize the different possible paths to spin-orbit misalignment as a
function of various physical parameters (e.g. planet mass and stellar rotation
period). We identify five distinct spin-orbit evolution paths and outcomes,
only two of which are capable of producing retrograde orbits. We show that
these paths to misalignment and the outcomes depend only on two dimensionless
parameters, which compare the stellar spin precession frequency with the rate
of change of the planet's orbital axis, and the Lidov-Kozai oscillation
frequency. Our analysis reveals a number of novel phenomena for the stellar
spin evolution, ranging from bifurcation, adiabatic advection, to fully chaotic
evolution of spin-orbit angles.


title:
Tolerant Junta Testing and the Connection to Submodular Optimization and
  Function Isomorphism

abstract:
  A function $f\colon \{-1,1\}^n \to \{-1,1\}$ is a $k$-junta if it depends on
at most $k$ of its variables. We consider the problem of tolerant testing of
$k$-juntas, where the testing algorithm must accept any function that is
$\epsilon$-close to some $k$-junta and reject any function that is
$\epsilon'$-far from every $k'$-junta for some $\epsilon'= O(\epsilon)$ and $k'
= O(k)$.
  Our first result is an algorithm that solves this problem with query
complexity polynomial in $k$ and $1/\epsilon$. This result is obtained via a
new polynomial-time approximation algorithm for submodular function
minimization (SFM) under large cardinality constraints, which holds even when
only given an approximate oracle access to the function.
  Our second result considers the case where $k'=k$. We show how to obtain a
smooth tradeoff between the amount of tolerance and the query complexity in
this setting. Specifically, we design an algorithm that given $\rho\in(0,1/2)$
accepts any function that is $\frac{\epsilon\rho}{16}$-close to some $k$-junta
and rejects any function that is $\epsilon$-far from every $k$-junta. The query
complexity of the algorithm is $O\big( \frac{k\log k}{\epsilon\rho(1-\rho)^k}
\big)$.
  Finally, we show how to apply the second result to the problem of tolerant
isomorphism testing between two unknown Boolean functions $f$ and $g$. We give
an algorithm for this problem whose query complexity only depends on the
(unknown) smallest $k$ such that either $f$ or $g$ is close to being a
$k$-junta.


title: Suppressed $B \to PV $ CP asymmetry: CPT constraint

abstract:
  Charge Parity asymmetry in charmless B meson decays is a key issue to be
understood. Many theoretical calculations have been performed using short
distance factorization approaches which, in general, do not take into account
the CPT invariance constraint. For each channel with CP violation there is an
equal amount of CP asymmetry in another channel or other channels, with an
opposite sign. This happens if these channels are coupled through final state
interactions (FSI). In the specific process $B\to PV$, involving one
pseudo-scalar and one vector particle in the final state, we argue that the CP
asymmetry, inherent from a short distance mechanism, could be suppressed due to
the CPT constraint. In this case, we propose a sensitive and practical
experimental method to identify even a small CP asymmetry, which provides the
values for $A_{CP}$ without the need for an amplitude analysis. This method, if
applied directly to data, will enable to extract the CP asymmetry information
in a model independent way and check to which extend the suggested suppression
due to the CPT constraint is verified.


title: Quasinonlocal coupling of nonlocal diffusions

abstract:
  We developed a new self-adjoint, consistent, and stable coupling strategy for
nonlocal diffusion models, inspired by the quasinonlocal atomistic-to-continuum
method for crystalline solids. The proposed coupling model is coercive with
respect to the energy norms induced by the nonlocal diffusion kernels as well
as the $L^2$ norm, and it satisfies the maximum principle. A finite difference
approximation is used to discretize the coupled system, which inherits the
property from the continuous formulation. Furthermore, we design a numerical
example which shows the discrepancy between the fully nonlocal and fully local
diffusions, whereas the result of the coupled diffusion agrees with that of the
fully nonlocal diffusion.


title: Coherence Constraints and the Last Hidden Optical Coherence

abstract:
  We have discovered a new domain of optical coherence, and show that it is the
third and last member of a previously unreported fundamental triad of
coherences. These are unified by our derivation of a parallel triad of
coherence constraints that take the form of complementarity relations. We have
been able to enter this new coherence domain experimentally and we describe the
novel tomographic approach devised for that purpose.


title:
Primeness property for graded central polynomials of verbally prime
  algebras

abstract:
  Let $F$ be an infinite field. The primeness property for central polynomials
of $M_n(F)$ was proved by A. Regev, i.e., if the product of two polynomials in
distinct variables is central then each factor is also central. In this paper
we consider the analogous property for $M_n(F)$ and determine, within the
elementary gradings with commutative neutral component, the ones that satisfy
this property, namely the crossed product gradings. Next we consider $M_n(R)$,
where $R$ admits a regular grading, with a grading such that $M_n(F)$ is a
homogeneous subalgebra and provide sufficient conditions - satisfied by
$M_n(E)$ with the trivial grading - to prove that $M_n(R)$ has the primeness
property if $M_n(F)$ does. We also prove that the algebras $M_{a,b}(E)$ satisfy
this property for ordinary central polynomials. Hence over a field of
characteristic zero every verbally prime algebra as the primeness property.


title:
Generalized hybrid iterative methods for large-scale Bayesian inverse
  problems

abstract:
  We develop a generalized hybrid iterative approach for computing solutions to
large-scale Bayesian inverse problems. We consider a hybrid algorithm based on
the generalized Golub-Kahan bidiagonalization for computing Tikhonov
regularized solutions to problems where explicit computation of the square root
and inverse of the covariance kernel for the prior covariance matrix is not
feasible. This is useful for large-scale problems where covariance kernels are
defined on irregular grids or are only available via matrix-vector
multiplication, e.g., those from the Mat\'{e}rn class. We show that iterates
are equivalent to LSQR iterates applied to a directly regularized Tikhonov
problem, after a transformation of variables, and we provide connections to a
generalized singular value decomposition filtered solution. Our approach shares
many benefits of standard hybrid methods such as avoiding semi-convergence and
automatically estimating the regularization parameter. Numerical examples from
image processing demonstrate the effectiveness of the described approaches.


title:
Formulation and convergence of the finite volume method for conservation
  laws on spacetimes with boundary

abstract:
  We study nonlinear hyperbolic conservation laws posed on a differential
(n+1)-manifold with boundary referred to as a spacetime, and defined from a
prescribed flux field of n-forms depending on a parameter (the unknown
variable), a class of equations proposed by LeFloch and Okutmustur in 2008. Our
main result is a proof of the convergence of the finite volume method for weak
solutions satisfying suitable entropy inequalities. A main difference with
previous work is that we allow for slices with a boundary and, in addition,
introduce a new formulation of the finite volume method involving the notion of
total flux functions. Under a natural global hyperbolicity condition on the
flux field and the spacetime and by assuming that the spacetime admits a
foliation by compact slices with boundary, we establish an existence and
uniqueness theory for the initial and boundary value problem, and we prove a
contraction property in a geometrically natural L1-type distance.


title: Electronic properties of LaAlO3/SrTiO3 n-type interfaces: A GGA+U study

abstract:
  The role of electronic correlation effects for a realistic description of the
electronic properties of LaAlO3/SrTiO3 heterostructures as covered by the
on-site Coulomb repulsion within the GGA+U approach is investigated. Performing
a systematic variation of the values of the Coulomb parameters applied to the
Ti 3d and La 4f orbitals we put previous suggestions to include a large value
for the La 4f states into perspective. Furthermore, our calculations provide
deeper insight into the band gap landscape in the space spanned by these
Coulomb parameters and the resulting complex interference effects. In addition,
we identify important correlations between the local Coulomb interaction within
the La 4f shell, the band gap, and the atomic displacements at the interface.
In particular, these on-site Coulomb interactions influence buckling within the
LaO interface layer, which via its strong coupling to the electrostatic
potential in the LAO overlayer causes considerable shifts of the electronic
states at the surface and eventually controls the band gap.


title: VisiSploit: An Optical Covert-Channel to Leak Data through an Air-Gap

abstract:
  In recent years, various out-of-band covert channels have been proposed that
demonstrate the feasibility of leaking data out of computers without the need
for network connectivity. The methods proposed have been based on different
type of electromagnetic, acoustic, and thermal emissions. However, optical
channels have largely been considered less covert: because they are visible to
the human eye and hence can be detected, they have received less attention from
researchers. In this paper, we introduce VisiSploit, a new type of optical
covert channel which, unlike other optical methods, is also stealthy. Our
method exploits the limitations of human visual perception in order to
unobtrusively leak data through a standard computer LCD display. Our
experiments show that very low contrast or fast flickering images which are
invisible to human subjects, can be recovered from photos taken by a camera.
Consequentially, we show that malicious code on a compromised computer can
obtain sensitive data (e.g., images, encryption keys, passwords), and project
it onto a computer LCD screen, invisible and unbeknownst to users, allowing an
attacker to reconstruct the data using a photo taken by a nearby (possibly
hidden) camera. In order to demonstrate the feasibility of this type of attack
and evaluate the channel's stealth, we conducted a battery of tests with 40
human subjects. We also examined the channel's boundaries under various
parameters, with different types of encoded objects, at several distances, and
using several kinds of cameras. Our results show that binary data can be leaked
via our covert channel. Further research and discussion may widen the scope of
this field beyond its current boundaries, yielding novel attack paradigms that
exploit the subtle mechanisms of human visual perception.


title:
Symbolic Representation and Classification of N=1 Supersymmetric
  Evolutionary Equations

abstract:
  We extend the symbolic representation to the ring of N=1 supersymmetric
differential polynomials, and demonstrate that operations on the ring, such as
the super derivative, Frechet derivative and super commutator, can be carried
out in the symbolic way. Using the symbolic representation, we classify scalar
$\lambda$-homogeneous N=1 supersymmetric evolutionary equations with nonzero
linear term when $\lambda>0$ for arbitrary order and give a comprehensive
description of all such integrable equations.


title: Making recommendations bandwidth aware

abstract:
  This paper asks how much we can gain in terms of bandwidth and user
satisfaction, if recommender systems became bandwidth aware and took into
account not only the user preferences, but also the fact that they may need to
serve these users under bandwidth constraints, as is the case over wireless
networks. We formulate this as a new problem in the context of index coding: we
relax the index coding requirements to capture scenarios where each client has
preferences associated with messages. The client is satisfied to receive any
message she does not already have, with a satisfaction proportional to her
preference for that message. We consistently find, over a number of scenarios
we sample, that although the optimization problems are in general NP-hard,
significant bandwidth savings are possible even when restricted to polynomial
time algorithms.


title: Large Scale SfM with the Distributed Camera Model

abstract:
  We introduce the distributed camera model, a novel model for
Structure-from-Motion (SfM). This model describes image observations in terms
of light rays with ray origins and directions rather than pixels. As such, the
proposed model is capable of describing a single camera or multiple cameras
simultaneously as the collection of all light rays observed. We show how the
distributed camera model is a generalization of the standard camera model and
describe a general formulation and solution to the absolute camera pose problem
that works for standard or distributed cameras. The proposed method computes a
solution that is up to 8 times more efficient and robust to rotation
singularities in comparison with gDLS. Finally, this method is used in an novel
large-scale incremental SfM pipeline where distributed cameras are accurately
and robustly merged together. This pipeline is a direct generalization of
traditional incremental SfM; however, instead of incrementally adding one
camera at a time to grow the reconstruction the reconstruction is grown by
adding a distributed camera. Our pipeline produces highly accurate
reconstructions efficiently by avoiding the need for many bundle adjustment
iterations and is capable of computing a 3D model of Rome from over 15,000
images in just 22 minutes.


title: The response of small SQUID pickup loops to magnetic fields

abstract:
  In the past, magnetic images acquired using scanning Superconducting Quantum
Interference Device (SQUID) microscopy have been interpreted using simple
models for the sensor point spread function. However, more complicated modeling
is needed when the characteristic dimensions of the field sensitive areas in
these sensors become comparable to the London penetration depth. In this paper
we calculate the response of SQUIDs with deep sub-micron pickup loops to
different sources of magnetic fields by solving coupled London's and Maxwell's
equations using the full sensor geometry. Tests of these calculations using
various field sources are in reasonable agreement with experiments. These
calculations allow us to more accurately interpret sub-micron spatial
resolution data obtained using scanning SQUID microscopy.


title:
Large-Scale Arrays of Single- and Few-Layer MoS2 Nanomechanical
  Resonators

abstract:
  We report on fabrication of large-scale arrays of suspended molybdenum
disulfide (MoS2) atomic layers, as two-dimensional (2D) MoS2 nanomechanical
resonators. We employ a water-assisted lift-off process to release chemical
vapor deposited (CVD) MoS2 atomic layers from a donor substrate, followed by an
all-dry transfer onto microtrench arrays. The resultant large arrays of
suspended single- and few-layer MoS2 drumhead resonators (0.5 to 2um in
diameter) offer fundamental resonances (f_0) in the very high frequency (VHF)
band (up to ~120MHz) and excellent figures-of-merit up to f_0*Q ~ 3*10^10Hz. A
stretched circular diaphragm model allows us to estimate low pre-tension levels
of typically ~15mN/m in these devices. Compared to previous approaches, our
transfer process features high yield and uniformity with minimal liquid and
chemical exposure (only involving DI water), resulting in high-quality MoS2
crystals and exceptional device performance and homogeneity; and our process is
readily applicable to other 2D materials.


title: Scalar-tensor extension of the $\Lambda$CDM model

abstract:
  We construct a cosmological scalar-tensor-theory model in which the
Brans-Dicke type scalar $\Phi$ enters the effective (Jordan-frame) Hubble rate
as a simple modification of the Hubble rate of the $\Lambda$CDM model. This
allows us to quantify differences between the background dynamics of
scalar-tensor theories and general relativity (GR) in a transparent and
observationally testable manner in terms of one single parameter. Problems of
the mapping of the scalar-field degrees of freedom on an effective fluid
description in a GR context are discused. Data from supernovae, the
differential age of old galaxies and baryon acoustic oscillations are shown to
strongly limit potential deviations from the standard model.


title:
Probing 5f-state configurations in URu2Si2 with U L3-edge resonant x-ray
  emission spectroscopy

abstract:
  Resonant x-ray emission spectroscopy (RXES) was employed at the U L3
absorption edge and the La1 emission line to explore the 5f occupancy, nf, and
the degree of 5f orbital delocalization in the hidden order compound URu2Si2.
By comparing to suitable reference materials such as UF4, UCd11, and alpha-U,
we conclude that the 5f orbital in URu2Si2 is at least partially delocalized
with nf = 2.87 +/- 0.08, and does not change with temperature down to 10 K
within the estimated error. These results place further constraints on
theoretical explanations of the hidden order, especially those requiring a
localized f2 ground state.


title: Ensemble preconditioning for Markov chain Monte Carlo simulation

abstract:
  We describe parallel Markov chain Monte Carlo methods that propagate a
collective ensemble of paths, with local covariance information calculated from
neighboring replicas. The use of collective dynamics eliminates multiplicative
noise and stabilizes the dynamics thus providing a practical approach to
difficult anisotropic sampling problems in high dimensions. Numerical
experiments with model problems demonstrate that dramatic potential speedups,
compared to various alternative schemes, are attainable.


title: A draft genome assembly of southern bluefin tuna Thunnus maccoyii

abstract:
  Tuna are large pelagic fish whose populations are close to panmixia. In
addition, they are threatened species, so it is important for the maintenance
and monitoring of genetic diversity that genetic information at a genome level
be obtained. Here we report the draft assembly of the southern bluefin tuna
genome and the collection of genome-wide sequence data for five other tuna
species. We sampled five tuna species of the genus Thunnus, the northern and
southern bluefin, yellowfin, albacore, and bigeye, as well as the skipjack
(Katsuwonis pelamis), a tuna-like species. Genome assembly was facilitated at
k-mer=25 while k-mer=51 generated assembly artefacts. The estimated size of the
southern bluefin tuna genome was 795 Mb. We assembled two southern bluefin tuna
individuals independently using both paired end and mate pair sequence. This
resulted in scaffolds with N50>174,000 bp and maximum scaffold lengths>1.4 Mb.
Our estimate of the size of the assembled genome was the scaffolded sequences
in common to both assemblies, which amounted to 721 Mb of the 795 Mb of the
southern bluefin tuna genome sequence. Using BLAST, there were matches between
13,039 of 14,341 (91%) refseq mRNA of the zebrafish Danio rerio to the tuna
assembly indicating that most of a generic fish transcriptome was covered by
the assembly.


title:
Morphing of 2D Hole Systems at $\nu=3/2$ in Parallel Magnetic Fields:
  Compressible, Stripe, and Fractional Quantum Hall Phases

abstract:
  A transport study of two-dimensional (2D) holes confined to wide GaAs quantum
wells provides a glimpse of a subtle competition between different many-body
phases at Landau level filling $\nu=3/2$ in tilted magnetic fields. At large
tilt angles ($\theta$), an anisotropic, stripe (or nematic) phase replaces the
isotropic compressible Fermi sea at $\nu=3/2$ if the quantum well has a
symmetric charge distribution. When the charge distribution is made asymmetric,
instead of the stripe phase, an even-denominator fractional quantum state
appears at $\nu=3/2$ in a range of large $\theta$, and reverts back to a
compressible state at even higher $\theta$. We attribute this remarkable
evolution to the significant mixing of the excited and ground-state Landau
levels of 2D hole systems in tilted fields.


title:
Precision of readout at the hunchback gene: analyzing short
  transcription time traces in living fly embryos

abstract:
  The simultaneous expression of the hunchback gene in the numerous nuclei of
the developing fly embryo gives us a unique opportunity to study how
transcription is regulated in living organisms. A recently developed MS2-MCP
technique for imaging nascent messenger RNA in living Drosophila embryos allows
us to quantify the dynamics of the developmental transcription process. The
initial measurement of the morphogens by the hunchback promoter takes place
during very short cell cycles, not only giving each nucleus little time for a
precise readout, but also resulting in short time traces of transcription.
Additionally, the relationship between the measured signal and the promoter
state depends on the molecular design of the reporting probe. We develop an
analysis approach based on tailor made autocorrelation functions that overcomes
the short trace problems and quantifies the dynamics of transcription
initiation. Based on live imaging data, we identify signatures of bursty
transcription initiation from the hunchback promoter. We show that the
precision of the expression of the hunchback gene to measure its position along
the anterior-posterior axis is low both at the boundary and in the anterior
even at cycle 13, suggesting additional post-transcriptional averaging
mechanisms to provide the precision observed in fixed embryos.


title:
An Extremum-Seeking Co-Simulation Based Framework for Passivation Theory
  and its Application in Adaptive Cruise Control Systems

abstract:
  In this report, we apply an input-output transformation passivation method,
described in our previous works, to an Adaptive Cruise Control system. We
analyze the system's performance under a co-simulation framework that makes use
of an online optimization method called extremum-seeking to achieve the
optimized behavior. The matrix for passivation method encompasses commonly used
methods of series, feedback and feed-forward interconnections for passivating
the system. We have previously shown that passivity levels can be guaranteed
for a system using our passivation method. In this work, an extremum-seeking
algorithm was used to determine the passivation parameters. It is known that
systems with input-output time-delays are not passive. On the other hand,
time-delays are unavoidable in automotive systems and commonly emerge in
software implementations and communication units as well as driver's behavior.
We show that by using our passivation method, we can passivate the system and
improve its overall performance. Our simulation examples in CarSim and Simulink
will show that the passive system has a considerably better performance.


title: Gr\"unbaum coloring and its generalization to arbitrary dimension

abstract:
  This paper is a collection of thoughts and observations, being partly a
review and partly a report of current research, on recent work in various
aspects of Gr\"unbaum colorings, their existence and usage. In particular, one
of the most striking significances of Gr\"unbaum's Conjecture in the
2-dimensional case is its equivalence to the 4-Color Theorem. The notion of
Gr\"unbaum coloring is extended from the 2-dimensional case to the case of
arbitrary finite hyper-dimensions.


title:
Examining Student Participation in Two-Phase Collaborative Exams through
  Video Analysis

abstract:
  In this study we coded, for individual student participation on each
question, the video of twenty-seven groups interacting in the group phase of a
variety of two-phase exams. We found that maximum group participation occurred
on questions where at least one person in the group had answered that question
incorrectly during the solo phase of the exam. We also observed that those
students that were correct on a question during the solo phase have higher
participation than those that were incorrect. Finally we observed that, from a
participation standpoint, the strongest (weakest) students seem to benefit the
most (least) from heterogeneous groups, while homogeneous groups do not seem to
favor students of any particular performance level.