  We establish a general upper bound for $K$-fold cross-validation ($K$-CV)
errors that can be adapted to many $K$-CV-based estimators and learning
algorithms. Based on Rademacher complexity of the model and the
Orlicz-$\Psi_{\nu}$ norm of the error process, the CV error upper bound applies
to both light-tail and heavy-tail error distributions. We also extend the CV
error upper bound to $\beta$-mixing data using the technique of independent
blocking. We provide a Python package (\texttt{CVbound},
\url{https://github.com/isaac2math}) for computing the CV error upper bound in
$K$-CV-based algorithms. Using the lasso as an example, we demonstrate in
simulations that the upper bounds are tight and stable across different
parameter settings and random seeds. As well as accurately bounding the CV
errors for the lasso, the minimizer of the new upper bounds can be used as a
criterion for variable selection. Compared with the CV-error minimizer,
simulations show that tuning the lasso penalty parameter according to the
minimizer of the upper bound yields a more sparse and more stable model that
retains all of the relevant variables.


  The $\gamma$-Cambrian semilattices $\mathcal{C}_{\gamma}$ defined by Reading
and Speyer are a family of meet-semilattices associated with a Coxeter group
$W$ and a Coxeter element $\gamma\in W$, and they are lattices if and only if
$W$ is finite. In the case where $W$ is the symmetric group $\mathfrak{S}_{n}$
and $\gamma$ is the long cycle $(1\;2\;\ldots\;n)$ the corresponding
$\gamma$-Cambrian lattice is isomorphic to the well-known Tamari lattice
$\mathcal{T}_{n}$. Recently, Kallipoliti and the author have investigated
$\mathcal{C}_{\gamma}$ from a topological viewpoint, and showed that many
properties of the Tamari lattices can be generalized nicely. In the present
article this investigation is continued on a structural level using the
observation of Reading and Speyer that $\mathcal{C}_{\gamma}$ is
semidistributive. First we prove that every closed interval of
$\mathcal{C}_{\gamma}$ is a bounded-homomorphic image of a free lattice (in
fact it is a so-called $\mathcal{H\!H}$-lattice). Subsequently we prove that
each closed interval of $\mathcal{C}_{\gamma}$ is trim, we determine its
breadth, and we characterize the closed intervals that are dismantlable.


  We discuss the transverse momentum distribution of thermal and prompt photons
in ultrarelativistic heavy ion collisions. The prompt photons are mostly
produced by fragmentation of quark jets (bremsstrahlung). If these quark jets
suffer a large energy loss in heavy-ion reactions, prompt photons are
significantly suppressed. Thermal electromagnetic radiation from the
quark-gluon plasma and the hadron gas might then dominate the intermediate
k_T-range. In central Au+Au collisions at \sqrt{s}=200A GeV, and in the range 2
GeV < k_T < 4 GeV, the inverse slope of the thermal radiation is 360-460 MeV,
while that of the QCD photons is 500-1000 MeV. This large difference might
allow to disentangle the various sources of direct photons experimentally. At
\sqrt{s}=5.5A TeV, nuclear shadowing and quark-jet quenching suppresses the
QCD-photons strongly for k_T<5 GeV. Thermal radiation dominates in this
k_T-region.


  We explore what can be said on the effective temperature and sound speed of a
statistical ensemble of fluid phonons present at the onset of a conventional
inflationary phase. The phonons are the actual normal modes of the gravitating
and irrotational fluid that dominates the protoinflationary dynamics. The
bounds on the tensor to scalar ratio result in a class of novel constraints
involving the slow roll parameter, the sound speed of the phonons and the
temperature of the plasma prior to the onset of inflation. If the current size
of the Hubble radius coincides with the inflationary event horizon redshifted
down to the present epoch, the sound speed of the phonons can be assessed from
independent measurements of the tensor to scalar ratio and of the tensor
spectral index.


  Electromagnetic information theory (EIT) is an emerging interdisciplinary
subject that integrates classical Maxwell electromagnetics and Shannon
information theory. The goal of EIT is to uncover the information transmission
mechanisms from an electromagnetic (EM) perspective in wireless systems.
Existing works on EIT are mainly focused on the analysis of EM channel
characteristics, degrees-of-freedom, and system capacity. However, these works
do not clarify whether EIT can improve wireless communication systems. To fill
in this gap, in this paper, we provide a novel example that EIT can improve the
performance of classical minimum mean squared error (MMSE) channel estimators
by replacing the channel covariance matrix with an EM correlation function
(EMCF). Specifically, by averaging the solutions of Maxwell's equations over a
tunable angular distribution, we obtain a spatio-temporal correlation function
(STCF) of the EM channel, which we name as the EMCF. Since classical MMSE
estimators can exploit prior information contained in the channel covariance
matrix, the substitution of EMCF for the covariance matrix introduces EM side
information into MMSE estimators. Furthermore, we dynamically tune the EMCF
parameters to better fit the channel observations. Simulation results show that
the proposed EIT-MMSE channel estimator outperforms traditional MMSE
estimators, thus proving that EIT is beneficial to wireless communication
systems.


  We report on a recent study of the ground-state octet baryon masses using the
covariant baryon chiral perturbation theory with the extended-on-mass-shell
renormalization scheme up to next-to-next-to-next-to-leading order. By
adjusting the available 19 low-energy constants, a good fit of the $n_f=2+1$
lattice quantum chromodynamics results from the PACS-CS, LHPC, HSC, QCDSF-UKQCD
and NPLQCD collaborations is achieved.


  This note is based on my talk at ICCM 2013, Taipei. We give an exposition of
the group-theoretic method and recent results on the questions of non-emptiness
and dimension of affine Deligne-Lusztig varieties in affine flag varieties.


  We consider lepton mixing in an extension of the Standard Model with three
right-handed neutrino singlets. We require that the three lepton numbers L_e,
L_\mu, and L_\tau be separately conserved in the Yukawa couplings, and we
assume that they are softly broken only by the Majorana mass matrix M_R of the
neutrino singlets. In this framework, where lepton-number breaking occurs at a
scale much higher than the electroweak scale, deviations from
family-lepton-number conservation are calculable and finite, and lepton mixing
stems exclusively from M_R. We then show that a discrete symmetry exists such
that, in the lepton mixing matrix U, maximal atmospheric neutrino mixing
together with U_{e3}=0 can be obtained naturally. Alternatively, if one assumes
that there are two different scales in M_R and that the lepton number \bar L =
L_e - L_\mu - L_\tau is conserved in between them, then maximal solar neutrino
mixing follows naturally. If both the discrete symmetry and intermediate \bar L
conservation are introduced, bimaximal mixing is achieved.


  Data hiding has received much attention due to rapid development of internet
and multimedia technologies where security of information is a very important
concern. This is achieved by Steganography, which is the art or science of
hiding data into another data, so that human eyes cannot catch the hidden
information easily. There are many ways to hide information-like inside an
image, text, audio/ video etc. Among them image steganography is a very
attractive research area. The goal is to transmit a data within a modified
image (called stego-image)by minimizing the number of bit flips. In this paper,
a new steganography technique has been proposed using Graphical codes and also
comparison with steganography technique using BCH codes has been studied.


  In many common scenarios, programmers need to implement functionality that is
already provided by some third party library. This paper presents a tool called
Hunter that facilitates code reuse by finding relevant methods in large code
bases and automatically synthesizing any necessary wrapper code. The key
technical idea underlying our approach is to use types to both improve search
results and guide synthesis. Specifically, our method computes similarity
metrics between types and uses this information to solve an integer linear
programming (ILP) problem in which the objective is to minimize the cost of
synthesis. We have implemented Hunter as an Eclipse plug-in and evaluate it by
(a) comparing it against S6, a state-of-the-art code reuse tool, and (b)
performing a user study. Our evaluation shows that Hunter compares favorably
with S6 and significantly increases programmer productivity.


  Driver behavior profiling is one of the main issues in the insurance
industries and fleet management, thus being able to classify the driver
behavior with low-cost mobile applications remains in the spotlight of
autonomous driving. However, using mobile sensors may face the challenge of
security, privacy, and trust issues. To overcome those challenges, we propose
to collect data sensors using Carla Simulator available in smartphones
(Accelerometer, Gyroscope, GPS) in order to classify the driver behavior using
speed, acceleration, direction, the 3-axis rotation angles (Yaw, Pitch, Roll)
taking into account the speed limit of the current road and weather conditions
to better identify the risky behavior. Secondly, after fusing inter-axial data
from multiple sensors into a single file, we explore different machine learning
algorithms for time series classification to evaluate which algorithm results
in the highest performance.


  We study a new paradigm for sequential decision making, called offline policy
learning from observations (PLfO). Offline PLfO aims to learn policies using
datasets with substandard qualities: 1) only a subset of trajectories is
labeled with rewards, 2) labeled trajectories may not contain actions, 3)
labeled trajectories may not be of high quality, and 4) the data may not have
full coverage. Such imperfection is common in real-world learning scenarios,
and offline PLfO encompasses many existing offline learning setups, including
offline imitation learning (IL), offline IL from observations (ILfO), and
offline reinforcement learning (RL). In this work, we present a generic
approach to offline PLfO, called $\textbf{M}$odality-agnostic
$\textbf{A}$dversarial $\textbf{H}$ypothesis $\textbf{A}$daptation for
$\textbf{L}$earning from $\textbf{O}$bservations (MAHALO). Built upon the
pessimism concept in offline RL, MAHALO optimizes the policy using a
performance lower bound that accounts for uncertainty due to the dataset's
insufficient coverage. We implement this idea by adversarially training
data-consistent critic and reward functions, which forces the learned policy to
be robust to data deficiency. We show that MAHALO consistently outperforms or
matches specialized algorithms across a variety of offline PLfO tasks in theory
and experiments. Our code is available at https://github.com/AnqiLi/mahalo.


  We present an analysis of a variational coherent-squeezed state that has been
discussed in the literature as a potential ground state for the spin-boson
model. We show that when the system-size scaling of the spin-bath coupling is
included properly, all squeezing effects and non-universal physics vanish in
the thermodynamic limit. We also present finite-size corrections to the
renormalisation of the spin's coherence, showing that squeezing effects are
also absent to leading order in the inverse bath-size.


  We report on the very low $\alpha$-element abundances of a group of
metal-poor stars with high orbital energy and with large retrograde motion in
the Milky Way halo, whose excess has been reported recently from metallicity
and kinematics. We constructed a sample of halo stars with measured abundances
and precise kinematics, including $\sim 880$ stars with [{{Fe}/{H}}]$<-0.7$, by
crossmatching the Stellar Abundances for Galactic Archaeology database to the
second data release of Gaia. Three regions in the energy-angular momentum space
have been selected: innermost halo, Gaia Enceladus/Sausage, and high-energy
retrograde halo. While the innermost halo and Gaia Enceladus regions have
chemical abundances consistent with high- and low-$\alpha$ populations in the
halo, respectively, chemical abundances of stars in the high-energy retrograde
halo are different from the two populations; their [{X}/{Fe}], where X
represents Na, Mg, and Ca, are even lower than those in Gaia Enceladus. These
abundances, as well as their low mean metallicity, provide a new support for
the idea that the retrograde component is dominated by an accreted dwarf galaxy
which has a longer star formation timescale and is less massive than Gaia
Enceladus/Sausage.


  We report the discovery of a $>1^\circ$ ($\sim50$ kpc) long stellar tidal
stream emanating from the dwarf galaxy DDO 44, a likely satellite of Local
Volume galaxy NGC 2403 located $\sim70$ kpc in projection from its companion.
NGC 2403 is a roughly Large Magellanic Cloud stellar-mass galaxy 3 Mpc away,
residing at the outer limits of the M 81 group. We are mapping a large region
around NGC 2403 as part of our MADCASH (Magellanic Analogs' Dwarf Companions
and Stellar Halos) survey, reaching point source depths (90% completeness) of
($g, i$) = (26.5, 26.2). Density maps of old, metal-poor RGB stars reveal tidal
streams extending on two sides of DDO 44, with the streams directed toward NGC
2403. We estimate total luminosities of the original DDO 44 system (dwarf and
streams combined) to be $M_{i, \rm{tot}} = -13.4$ and $M_{g, \rm{tot}} =
-12.6$, with $\sim25-30\%$ of the luminosity in the streams. Analogs of
$\sim$LMC-mass hosts with massive tidally disrupting satellites are rare in the
Illustris simulations, especially at large separations such as that of DDO 44.
The few analogs that are present in the models suggest that even low-mass hosts
can efficiently quench their massive satellites.


  We express the condition for a phase space Gaussian to be the Wigner
distribution of a mixed quantum state in terms of the symplectic capacity of
the associated Wigner ellipsoid. Our results are motivated by Hardy's
formulation of the uncertainty principle for a function and its Fourier
transform. As a consequence we are able to state a more general form of Hardy's
theorem.


  Starting from a symmetric triangular pile with a horizontal basis and
rotating the basis in the vertical plane, we have determined the evolution of
the stress distribution as a function of the basis inclination using Finite
Elements method with an elastic-perfectly plastic constitutive model, defined
by its friction angle, without cohesion. It is found that when the yield
function is the Drucker-Prager one, stress distribution satisfying equilibrium
can be found even when one of the free-surface slopes is larger than the
friction angle. This means that piles with a slope larger than the friction
angle can be (at least) marginally stable and that slope rotation is not always
a destabilising perturbation direction. On the contrary, it is found that the
slope cannot overpass the friction angle when a Mohr-Coulomb yield function is
used. Theoretical explanation of these facts is given which enlightens the role
plaid by the intermediate principal stress in both cases of the Mohr-Coulomb
criterion and of the Drucker-Prager one. It is then argued that the
Mohr-Coulomb criterion assumes a spontaneous symmetry breaking, as soon as the
two smallest principal stresses are different ; this is not physical most
likely; so this criterion shall be replaced by a Drucker-Prager criterion in
the vicinity of the equality, which leads to the previous anomalous behaviour ;
so these numerical computations enlighten the avalanche process: they show that
no dynamical angle larger than the static one is needed to understand
avalanching. It is in agreement with previous experimental results.
Furthermore, these results show that the maximum angle of repose can be
modified using cyclic rotations; we propose a procedure that allows to achieve
a maximum angle of repose to be equal to the friction angle .


  Subsequence anomaly detection in long sequences is an important problem with
applications in a wide range of domains. However, the approaches proposed so
far in the literature have severe limitations: they either require prior domain
knowledge used to design the anomaly discovery algorithms, or become cumbersome
and expensive to use in situations with recurrent anomalies of the same type.
In this work, we address these problems, and propose an unsupervised method
suitable for domain agnostic subsequence anomaly detection. Our method,
Series2Graph, is based on a graph representation of a novel low-dimensionality
embedding of subsequences. Series2Graph needs neither labeled instances (like
supervised techniques) nor anomaly-free data (like zero-positive learning
techniques), and identifies anomalies of varying lengths. The experimental
results, on the largest set of synthetic and real datasets used to date,
demonstrate that the proposed approach correctly identifies single and
recurrent anomalies without any prior knowledge of their characteristics,
outperforming by a large margin several competing approaches in accuracy, while
being up to orders of magnitude faster. This paper has appeared in VLDB 2020.


  We show how to assign initial data for the characteristic
Einstein-Yang-Mills-Higgs system on two intersecting smooth null hypersurfaces.
We successfully adapt the hierarchical method set up by A. D. Rendall to solve
the same problem for the Einstein equations in vacuum and with perfect fluid
source. Unlike the work of Rendall, many delicate calculations and expressions
are given in details so as to address, in a forthcoming work, the issue of
global resolution of the characteristic initial value problem for the
Einstein-Yang-Mills-Higgs system. The method obviously applies to the
Einstein-Maxwell and the Einstein-scalar field models.


  We prove the existence of a critical subsolution of the Hamilton-Jacobi
equation which is differentiable with Lipschitz differential, improving a
previous result of Fathi and Siconolfi. This text is a consolidated version
with a minor mistake corrected from the published version.


  This is a computational study of gravity-driven fingering instabilities in
unsaturated porous media. The governing equations and corresponding numerical
scheme are based on the work of Nieber et al. [Ch. 23 in Soil Water Repellency,
eds. C. J. Ritsema and L. W. Dekker, Elsevier, 2003] in which non-monotonic
saturation profiles are obtained by supplementing the Richards equation with a
non-equilibrium capillary pressure-saturation relationship, as well as
including hysteretic effects. The first part of the study takes an extensive
look at the sensitivity of the finger solutions to certain key parameters in
the model such as capillary shape parameter, initial saturation, and capillary
relaxation coefficient. The second part is a comparison to published
experimental results that demonstrates the ability of the model to capture
realistic fingering behaviour.


  We obtained total radiation widths of s-wave resonances through R-matrix
analysis of 147Sm(n,gamma) cross-sections. Distributions of these widths differ
markedly for resonances below and above 300 eV, in stark contrast to
long-established theory. We show that this change, as well as a similar change
in the neutron-width distribution reported previously, are reflected in abrupt
increases in both the average 147Sm(n,gamma) cross section and fluctuations
about the average near 300 eV. Such effects could have important consequences
for applications such as nuclear astrophysics and nuclear criticality safety.


  The attention-based Transformers have been increasingly applied to audio
classification because of their global receptive field and ability to handle
long-term dependency. However, the existing frameworks which are mainly
extended from the Vision Transformers are not perfectly compatible with audio
signals. In this paper, we introduce a Causal Audio Transformer (CAT)
consisting of a Multi-Resolution Multi-Feature (MRMF) feature extraction with
an acoustic attention block for more optimized audio modeling. In addition, we
propose a causal module that alleviates over-fitting, helps with knowledge
transfer, and improves interpretability. CAT obtains higher or comparable
state-of-the-art classification performance on ESC50, AudioSet and UrbanSound8K
datasets, and can be easily generalized to other Transformer-based models.


  Stein variational gradient descent (SVGD) is a deterministic particle
inference algorithm that provides an efficient alternative to Markov chain
Monte Carlo. However, SVGD has been found to suffer from variance
underestimation when the dimensionality of the target distribution is high.
Recent developments have advocated projecting both the score function and the
data onto real lines to sidestep this issue, although this can severely
overestimate the epistemic (model) uncertainty. In this work, we propose
Grassmann Stein variational gradient descent (GSVGD) as an alternative
approach, which permits projections onto arbitrary dimensional subspaces.
Compared with other variants of SVGD that rely on dimensionality reduction,
GSVGD updates the projectors simultaneously for the score function and the
data, and the optimal projectors are determined through a coupled
Grassmann-valued diffusion process which explores favourable subspaces. Both
our theoretical and experimental results suggest that GSVGD enjoys efficient
state-space exploration in high-dimensional problems that have an intrinsic
low-dimensional structure.


  Photometric properties of various spectral libraries of synthetic stellar
spectra derived from the ATLAS 9 (Castelli et al. 1997), the PHOENIX NextGen
(Hauschildt et al. 1999a, 1999b), the NMARCS (Bessell et al. 1998), and the
BaSeL (Lejeune et al. 1998, Westera et al. 2002) models are discussed in view
of their application to the definition of the GAIA photometric system.
Comparisons with empirical UBVRI calibrations show significant discrepancies at
low temperatures between the different models, and with respect to the \basel
3.1 and the Alonso et al. (1998, 1999) empirical calibrations.


  We theoretically investigate a photonic Kagome lattice which can be realized
in microwave cavity arrays using current technology. The Kagome lattice
exhibits an exotic band structure with three bands one of which can be made
completely flat. The presence of artificial gauge fields allows to emulate
topological phases and induce chiral edge modes which can coexist inside the
energy gap with the flat band that is topologically trivial. By tuning the
artificial fluxes or in the presence of disorder, the flat band can also
acquire a bandwidth in energy allowing the coexistence between chiral edge
modes and bulk extended states; in this case the chiral modes become fragile
towards scattering into the bulk. The photonic system then exhibits equivalents
of both a quantum Hall effect without Landau levels, and an anomalous Hall
effect characterized by a non-quantized Chern number. We discuss experimental
observables such as local density of states and edge currents. We show how
synthetic uniform magnetic fields can be engineered, which allows an
experimental probe of Landau levels in the photonic Kagome lattice. We then
draw on semiclassical Boltzmann equations for transport to devise a method to
measure Berry's phases around loops in the Brillouin zone. The method is based
solely on wavepacket interference and can be used to determine band Chern
numbers or the photonic equivalent of the anomalous Hall response. We
demonstrate the robustness of these measurements towards on-site and
gauge-field disorder. We also show the stability of the anomalous quantum Hall
phase for nonlinear cavities and for (artificial) atom-photon interactions.


  We find a new class of spiky solutions for closed strings in flat,
$AdS_3\subset AdS_5$ and $R\times S^2(\subset S^5)$ backgrounds. In the flat
case the new solutions turn out to be T-dual configurations of spiky strings
found by Kruczenski hep-th/0410226. In the case of solutions living in $AdS$,
we make a semi classical analysis by taking the large angular momentum limit.
The anomalous dimension for these dual spikes is similar to that for rotating
and pulsating circular strings in AdS with angular momentum playing the role of
the level number. This replaces the well known logarithmic dependence for
spinning strings. For the dual spikes living on sphere we find that no large
angular momentum limit exists.


  A recent paper [F. Radicchi and A. Arenas, Nature Phys. 9, 717 (2013)]
presented the finding of an abrupt transition in the structure of
interconnected networks. This transition was said to be generic and to occur
even in networks of finite size. Furthermore, it was remarked that this
singular behaviour could be understood in the spirit of a first-order phase
transition. We show here that the generic singularity found in that paper is a
trivial consequence of the reducibility of the "supra-Laplacian" operator
studied. The singular changes observed are therefore not related to any
collective abrupt structural transformation in the interconnected networks.


  For a fixed graph $H$, in the graph homomorphism problem, denoted by
$Hom(H)$, we are given a graph $G$ and we have to determine whether there
exists an edge-preserving mapping $\varphi: V(G) \to V(H)$. Note that
$Hom(C_3)$, where $C_3$ is the cycle of length $3$, is equivalent to
$3$-Coloring. The question whether $3$-Coloring is polynomial-time solvable on
diameter-$2$ graphs is a well-known open problem. In this paper we study the
$Hom(C_{2k+1})$ problem on bounded-diameter graphs for $k\geq 2$, so we
consider all other odd cycles than $C_3$. We prove that for $k\geq 2$, the
$Hom(C_{2k+1})$ problem is polynomial-time solvable on diameter-$(k+1)$ graphs
-- note that such a result for $k=1$ would be precisely a polynomial-time
algorithm for $3$-Coloring of diameter-$2$ graphs.
  Furthermore, we give subexponential-time algorithms for diameter-$(k+2)$ and
-$(k+3)$ graphs.
  We complement these results with a lower bound for diameter-$(2k+2)$ graphs
-- in this class of graphs the $Hom(C_{2k+1})$ problem is NP-hard and cannot be
solved in subexponential-time, unless the ETH fails.
  Finally, we consider another direction of generalizing $3$-Coloring on
diameter-$2$ graphs. We consider other target graphs $H$ than odd cycles but we
restrict ourselves to diameter $2$. We show that if $H$ is triangle-free, then
$Hom(H)$ is polynomial-time solvable on diameter-$2$ graphs.


  We endow twisted tensor products with a natural notion of counit and
comultiplication, and we provide sufficient and necessary conditions making the
twisted tensor product a counital coassociative coalgebra. We then characterize
when the twisted tensor product of bialgebras is a bialgebra, and when the
twisted tensor product of Frobenius algebras is a Frobenius algebra. Our
methods are purely diagrammatic, so these results hold for (braided) monoidal
categories. As an application, we recover that some quantum complete
intersections are Frobenius algebras, and we construct families of
noncommutative symmetric Frobenius algebras. Along the way, we also
characterize when twisted tensor products of separable algebras are separable,
and we prove that twisted tensor products of special Frobenius algebras are
special Frobenius.


  Renyi and von Neumann entropies quantifying the amount of entanglement in
ground states of critical spin chains are known to satisfy a universal law
which is given by the Conformal Field Theory (CFT) describing their scaling
regime. This law can be generalized to excitations described by primary fields
in CFT, as was done in reference (Alcaraz et. al., Phys. Rev. Lett. 106, 201601
(2011)), of which this work is a completion. An alternative derivation is
presented, together with numerical verifications of our results in different
models belonging to the c=1,1/2 universality classes. Oscillations of the Renyi
entropy in excited states and descendant fields are also discussed.


  The most precise realization of inertial reference frame in astronomy is the
catalogue of 212 defining extragalactic radiosources with coordinates obtained
during VLBI observation runs in 1979-1995. IAU decided on the development of
the second realization of the ICRF2 catalogue. The criteria of best sources
selection (in terms of coordinates stability) must be defined as the first aim.
The selected sources have to keep stable the coordinate axes of inertial
astronomical frame.
  Here we propose new criteria of source selection for the new ICRF catalogue.
The first one we call as "cosmological" and the second one as "kinematical".
The physical basis of these criteria is based on the assumption that apparent
motion of quasars (at angular scale of the order of hundred microarcseconds) is
connected with real motion inside quasars. Therefore apparent angular motion
corresponds to real physical motion of a "hot spot" inside a radio source. It
is shown that interval of redshift $0.8 \div 3.0$ is the most favorable in
terms that physical shift inside such sources corresponds to minimal apparent
angular shift of a "hot spot". Among "cosmologically" selected sources we
propose to select motionless sources and sources with linear motion which are
predictable and stable over long time interval.
  To select sources which satisfies such conditions we analyzed known redshifts
of sources and time series obtained by our code and by different centers of
analysis of VLBI data. As a result of these analyses we select 137 sources as a
basis for the ICRF2 catalogue.


  Pinning of superfluid vortices to magnetic flux tubes in the outer core of a
neutron star supports a velocity difference of $\sim 10^5$ \cms\ between the
neutron superfluid and the proton-electron fluid as the star spins down. Under
the Magnus force that arises on the vortex array, vortices undergo {\em vortex
creep} through thermal activation or quantum tunneling. We examine the
hydrodynamic stability of this situation. Vortex creep introduces two
low-frequency modes, one of which is unstable above a critical wavenumber for
any non-zero flow velocity of the neutron superfluid with respect to the
charged fluid. For typical pinning parameters of the outer core, the superfluid
flow is unstable over wavelengths $\lambda\lap 10$ m and over timescales of
$\sim (\lambda/{1 m})^{1/2}$ yr down to $\sim 1$ d. The vortex lattice could
degenerate into a tangle, and the superfluid flow would become turbulent. We
suggest that superfluid turbulence could be responsible for the red timing
noise seen in many neutron stars, and find a predicted spectrum that is
generally consistent with observations.


  A suitable coupling of the inflaton phi to a vector kinetic term F^2 gives
frozen and scale invariant vector perturbations. We compute the cosmological
perturbations zeta that result from such coupling by taking into account the
classical vector field that unavoidably gets generated at large scales during
inflation. This generically results in a too anisotropic power spectrum of
zeta. Specifically, the anisotropy exceeds the 1% level (10% level) if
inflation lasted ~5 e-folds (~50 e-folds) more than the minimal amount required
to produce the CMB modes. This conclusion applies, among others, to the
application of this mechanism for magnetogenesis, for anisotropic inflation,
and for the generation of anisotropic perturbations at the end of inflation
through a waterfall field coupled to the vector (in this case, the unavoidable
contribution that we obtain is effective all throughout inflation, and it is
independent of the waterfall field). For a tuned duration of inflation, a 1%
(10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum
which is enhanced like the local one in the squeezed limit, and with an
effective local f_{NL} ~3 (~30). More in general, a significant anisotropy of
the perturbations may be a natural outcome of all models that sustain higher
than 0 spin fields during inflation.


  For certain orientations of Josephson junctions between two p_x-wave or two
d-wave superconductors, the subgap Andreev bound states produce a 4pi-periodic
relation between the Josephson current I and the phase difference phi: I
sin(phi/2). Consequently, the ac Josephson current has the fractional frequency
eV/h, where V is the dc voltage. In the tunneling limit, the Josephson current
is proportional to the first power (not square) of the electron tunneling
amplitude. Thus, the Josephson current between unconventional superconductors
is carried by single electrons, rather than by Cooper pairs. The fractional ac
Josephson effect can be observed experimentally by measuring frequency spectrum
of microwave radiation from the junction. We also study junctions between
singlet s-wave and triplet p_x-wave, as well as between chiral p_x + ip_y-wave
superconductors.


  Internet of Things (IoT) is a system that consists of a large number of smart
devices connected through a network. The number of these devices is increasing
rapidly, which creates a massive and complex network with a vast amount of data
communicated over that network. One way to protect this data in transit, i.e.,
to achieve data confidentiality, is to use lightweight encryption algorithms
for IoT protocols. However, the design and implementation of such protocols is
an error-prone task; flaws in the implementation can lead to devastating
security vulnerabilities. These vulnerabilities can be exploited by an attacker
and affect users' privacy. There exist various techniques to verify software
and detect vulnerabilities. Bounded Model Checking (BMC) and Fuzzing are useful
techniques to check the correctness of a software system concerning its
specifications. Here we describe a framework called Encryption-BMC and Fuzzing
(EBF) using combined BMC and fuzzing techniques. We evaluate the application of
EBF verification framework on a case study, i.e., the S-MQTT protocol, to check
security vulnerabilities in cryptographic protocols for IoT.


  The generation of high-order harmonics in quasi-one-dimensional graphene
nanoribbons (GNRs) initiated by intense coherent radiation is investigated. A
microscopic theory describing the extreme nonlinear optical response of GNRs is
developed. The closed set of differential equations for the single-particle
density matrix at the GNR-strong laser field multiphoton interaction is solved
numerically. The obtained solutions indicate the significance of the bandgap
width and Fermi energy level on the high-order harmonic generation process in
GNRs.


  For over a century, reduced order models (ROMs) have been a fundamental
discipline of theoretical fluid mechanics. Early examples include Galerkin
models inspired by the Orr-Sommerfeld stability equation and numerous vortex
models, of which the von K\'arm\'an vortex street is one of the most prominent.
Subsequent ROMs typically relied on first principles, like mathematical
Galerkin models, weakly nonlinear stability theory, and two- and
three-dimensional vortex models. Aubry et al. [N. Aubry, P. Holmes, J. Lumley,
and E. Stone, Journal of Fluid Mechanics, 192, 115-173 (1988)] pioneered
data-driven proper orthogonal decomposition (POD) modeling. In early POD
modeling, available data was used to build an optimal basis, which was then
utilized in a classical Galerkin procedure to construct the ROM. But data has
made a profound impact on ROMs beyond the Galerkin expansion. In this paper, we
take a modest step and illustrate the impact of data-driven modeling on one
significant ROM area. Specifically, we focus on ROM closures, which are
correction terms that are added to classical ROMs in order to model the effect
of the discarded ROM modes in under-resolved simulations. Through simple
examples, we illustrate the main modeling principles used to construct
classical ROMs, motivate and introduce modern ROM closures, and show how
data-driven modeling, artificial intelligence, and machine learning have
changed the standard ROM methodology over the last two decades. Finally, we
outline our vision on how state-of-the-art data-driven modeling can continue to
reshape the field of reduced order modeling.


  In 1990, Lind, Schmidt and Ward gave a formula for the entropy of certain
$\mathbb{Z}^n$-dynamical systems attached to Laurent polynomials $P$, in terms
of the (logarithmic) Mahler measure of $P$. We extend the expansive case of
their result to the noncommutative setting where $\mathbb{Z}^n$ gets replaced
by suitable discrete amenable groups. Generalizing the Mahler measure,
Fuglede-Kadison determinants from the theory of group von Neumann algebras
appear in the entropy formula.


  In this article, I calculate the contributions of the nuclear matter induced
condensates up to dimension 5, take into account the next-to-leading order
contributions of the nuclear matter induced quark condensate, study the
properties of the scalar, pseudoscalar, vector and axial-vector heavy mesons in
the nuclear matter with the QCD sum rules in a systematic way, and obtain the
shifts of the masses and decay constants. Furthermore, I study the
heavy-meson-nucleon scattering lengths as a byproduct, and obtain the
conclusion qualitatively about the possible existence of heavy-meson-nucleon
bound states.


  Cherenkov Telescopes are equipped with optical dishes of large diameter -- in
general based on segmented mirrors -- with typical angular resolution of a few
arc-minutes. To evaluate the mirror's quality specific metrological systems are
required that possibly take into account the environmental conditions in which
typically these telescopes operate (in open air without dome protection). For
this purpose a new facility for the characterization of mirrors has been
developed at the labs of the Osservatorio Astronomico di Brera of the Italian
National Institute of Astrophysics. The facility allows the precise measurement
of the radius of curvature and the distribution of the concentred light in
terms of focused and scattered components and it works in open air. In this
paper we describe the facility and report some examples of its measuring
capabilities.


  We study stochastic Korteweg - de Vries equation driven by L\'evy noise
consisting of the compensated time homogeneous Poisson random measure and a
cylindrical Wiener process. We prove the existence of a martingale solution to
the equation studied. In proof of the existence theorem we use the Galerkin
approximation and several auxiliary results suitable for the problem
considered.


  I discuss the derivation and applications of Moving NRQCD (MNRQCD), a
generalization of NRQCD which allows the treatment of heavy quarks moving with
a finite velocity. This formalism is vital in reducing discretization errors in
calculations of large recoil decays, such as B --> K^* + gamma or the
Isgur-Wise function at large w.


  Can temporary subsidies to bundles induce long-run changes in demand due to
learning about the quality of one of the constituent goods? This paper provides
theoretical support and empirical evidence on this mechanism. Theoretically, we
introduce a model where an agent learns about the quality of an innovation
through repeated consumption. We then assess the predictions of our theory in a
randomised experiment in a ridesharing platform. The experiment subsidised car
trips integrating with a train or metro station, which we interpret as a
bundle. Given the heavy-tailed nature of our data, we propose a semiparametric
specification for treatment effects that enables the construction of more
efficient estimators. We then introduce an efficient estimator for our
specification by relying on L-moments. Our results indicate that a ten-weekday
50\% discount on integrated trips leads to a large contemporaneous increase in
the demand for integration, and, consistent with our model, persistent changes
in the mean and dispersion of nonintegrated app rides. These effects last for
over four months. A calibration of our theoretical model suggests that around
40\% of the contemporaneous increase in integrated rides may be attributable to
increased incentives to learning. Our results have nontrivial policy
implications for the design of public transit systems.


  Cooperation between individuals is emergent in all parts of society, yet
mechanistic reasons for this emergence is ill understood in the literature. A
specific example of this is insurance. Recent work has, though, shown that
assuming the risk individuals face is proportional to their wealth and
optimising the time average growth rate rather than the ensemble average
results in a non-zero-sum game, where both parties benefit from cooperation
through insurance contracts. In a recent paper, Peters and Skjold present a
simple agent-based model and show how, over time, agents that enter into such
cooperatives outperform agents that do not. Here, we extend this work by
restricting the possible connections between agents via a lattice network.
Under these restrictions, we still find that all agents profit from cooperating
through insurance. We, though, further find that clusters of poor and rich
agents emerge endogenously on the two-dimensional map and that wealth
inequalities persist for a long duration, consistent with the phenomenon known
as the poverty trap. By tuning the parameters which control the risk levels, we
simulate both highly advantageous and extremely risky gambles and show that
despite the qualitative shift in the type of risk, the findings are consistent.


  We discuss rotating wormholes in general relativity with a scalar field with
negative kinetic energy. To solve the problem, we use the assumption about slow
rotation. The role of a small dimensionless parameter plays the ratio of the
linear velocity of rotation of the wormhole's throat and the velocity of light.
We construct the rotating wormhole solution in the second order approximation
with respect to the small parameter. The analysis shows that the asymptotical
mass of the rotating wormhole is greater than that of the non-rotating one, and
the NEC violation in the rotating wormhole spacetime is weaker than that in the
non-rotating one.


  We calculate the cosmic microwave background (CMB) bispectrum due to
inhomogeneous reionization. We calculate all the terms that can contribute to
the bispectrum that are products of first order terms on all scales in
conformal Newtonian gauge. We also correctly account for the de-correlation
between the matter density and initial conditions using perturbation theory up
to third order. We find that the bispectrum is of local type as expected. For a
reasonable model of reionization, in which the Universe is completely ionized
by redshift z_{ri} ~ 8 with optical depth to the last scattering surface
\tau_0=0.087 the signal to noise for detection of the CMB temperature
bispectrum is S/N ~ 0.1 and confusion in the estimation of primordial
non-Gaussianity is f_{NL} ~ -0.1. For an extreme model with z_{ri} ~ 12.5,
\tau_0=0.14 we get S/N ~ 0.5 and f_{NL} ~ -0.2.


  The pixel-to-pixel spectral fitting technique is often used in studies of
stellar populations. It enables the user to infer several parameters from
integrated light spectra such as ages and chemical abundances. In this paper,
we examine the question of how the inferred parameters change with the choice
of wavelength range used. We have employed two different libraries of
integrated light spectra of globular clusters (GCs) from the literature and
fitted them to stellar population models using the code Starlight. We performed
tests using different regions of the spectra to infer reddening, ages, [Fe/H]
and [alpha/Fe]. Comparing our results to age values obtained from isochrone
fitting and chemical abundances from high resolution spectroscopy, we find
that: (1) The inferred parameters change with the wavelength range used; (2)
The method in general retrieves good reddening estimates, specially when a
wider wavelength range is fitted; (3) The ideal spectral regions for
determination of age, [Fe/H], and [alpha/Fe] are: 4170-5540A, 5280-7020A, and
4828-5364A, respectively; (4) The retrieved age values for old metal-poor
objects can be several Gyr younger than those resulting from isochrone fitting.
We conclude that, depending on the parameter of interest and the accuracy
requirements, fitting the largest possible wavelength range may not necessarily
be the best strategy.


  We represent a computer cluster as a multi-server queue with some arbitrary
bipartite graph of compatibilities between jobs and servers. Each server
processes its jobs sequentially in FCFS order. The service rate of a job at any
given time is the sum of the service rates of all servers processing this job.
We show that the corresponding queue is quasi-reversible and use this property
to design a scheduling algorithm achieving balanced fair sharing of the service
capacity.


  The low-power radio technologies open up many opportunities to facilitate
Internet-of-Things (IoT) into our daily life, while their minimalist design
also makes IoT devices vulnerable to many active attacks. Recent advances use
an antenna array to extract fine-grained physical-layer signatures to identify
the attackers, which adds burdens in terms of energy and hardware cost to IoT
devices. In this paper, we present ShieldScatter, a lightweight system that
attaches low-cost tags to single-antenna devices to shield the system from
active attacks. The key insight of ShieldScatter is to intentionally create
multi-path propagation signatures with the careful deployment of tags. These
signatures can be used to construct a sensitive profile to identify the
location of the signals' arrival, and thus detect the threat. In addition, we
also design a tag-random scheme and a multiple receivers combination approach
to detect a powerful attacker who has the strong priori knowledge of the
legitimate user. We prototype ShieldScatter with USRPs and tags to evaluate our
system in various environments. The results show that even when the powerful
attacker is close to the legitimate device, ShieldScatter can mitigate 95% of
attack attempts while triggering false alarms on just 7% of legitimate traffic.


  The mystery of where and how Nature accelerates the cosmic rays is still
unresolved a century after their discovery. Gamma ray bursts (GRBs) have been
proposed as one of the more plausible sources of extragalactic cosmic rays. A
positive observation of neutrinos in coincidence with a GRB would identify
these objects as sources of the highest-energy cosmic rays and provide
invaluable information about the processes occurring inside these phenomena.
Calculations show that a kilometer-scale neutrino telescope is necessary for
this task. The idea of such a detector is now becoming reality as IceCube at
the South Pole nears completion. The contribution reviews the status of the
construction and operation of IceCube and summarize the results from searches
for neutrinos from GRBs and similar phenomena with IceCube and its predecessor,
AMANDA. At the end, an outline of future plans and perspectives for IceCube is
given.


  The orbital distribution of the S-star cluster surrounding the supermassive
black hole in the center of the Milky Way is analyzed. A tight, roughly
exponential dependence of the pericenter distance r$_{p}$ on orbital
eccentricity e$_{\star}$ is found, $\log ($r$_p)\sim$(1-e$_{\star}$), which
cannot be explained simply by a random distribution of semi-major axes and
eccentricities. No stars are found in the region with high e$_{\star}$ and
large log r$_{p}$ or in the region with low e$_{\star}$ and small log r$_{p}$.
G-clouds follow the same correlation. The likelihood P(log
r$_p$,(1-e$_{\star}$)) to determine the orbital parameters of S-stars is
determined. P is very small for stars with large e$_{\star}$ and large log
r$_{p}$. S-stars might exist in this region. To determine their orbital
parameters, one however needs observations over a longer time period. On the
other hand, if stars would exist in the region of low log r$_{p}$ and small
e$_{\star}$, their orbital parameters should by now have been determined. That
this region is unpopulated therefore indicates that no S-stars exist with these
orbital characteristics, providing constraints for their formation. We call
this region, defined by $\log$ (r$_p$/AU) $<$ 1.57+2.6(1-e$_{\star})$, the zone
of avoidance. Finally, it is shown that the observed frequency of
eccentricities and pericenter distances is consistent with a random sampling of
log r$_{p}$ and e$_{\star}$. However, only if one takes into account that no
stars exist in the zone of avoidance and that orbital parameters cannot yet be
determined for stars with large r$_{p}$ and large e$_{\star}$.


  Grain Boundaries govern many properties of polycrystalline materials,
including the vast majority of engineering materials. Evolutionary algorithm
can be applied to predict the grain boundary structures in different systems.
However, the recognition and classification of thousands of predicted
structures is a very challenging work for eye detection in terms of efficiency
and accuracy. A data pipeline is developed to accelerate the classification and
recognition of grain boundary structures predicted by Evolutionary Algorithm.
The data pipeline has three main components including feature engineering of
grain boundary structures, density-based clustering analysis and parallel
K-Means clustering analysis. With this data pipeline, we could automate the
structure analysis and develop better structural and physical understanding of
grain boundaries.


  We estimate strong coupling constant between the negative parity nucleons
with $\pi$ meson within the light cone QCD sum rules. A method for eliminating
the unwanted contributions coming from the nucleon--nucleon and
nucleon--negative parity nucleon transition is presented. It is observed that
the value strong coupling constant of the negative parity nucleon $N^\ast
N^\ast \pi$ transition is considerably different from the one predicted by the
3--point QCD sum rules, but is quite close to the coupling constant of the
positive parity $N N \pi$ transition.


  Recent experiments show a strong rotational-diffusion enhancement for
self-propelled microrheological probes in colloidal glasses. Here, we provide
microscopic understanding using simulations with a frictional probe-medium
coupling that converts active translation into rotation. Diffusive enhancement
emerges from the medium's disordered structure and peaks at a second-order
transition in the number of contacts. Our results reproduce the salient
features of the colloidal glass experiment and support an effective description
that is applicable to a broader class of viscoelastic suspensions.


  Resonant vibrational strong coupling (VSC) between molecular vibrations and
quantized field modes of low-frequency optical cavities constitutes the
conceptual cornerstone of vibro-polaritonic chemistry. In this work, we
theoretically investigate complementary nonresonant electron-cavity
mode-interactions in the cavity Born-Oppenheimer (CBO) approximation. We focus
on cavity-induced modifications of local and non-local electronic interactions
in dipole-coupled molecular ensembles under VSC. Methodologically, we combine
CBO perturbation theory (CBO-PT) [Fischer, Saalfrank, JCTC 19, 7215 (2023)]
with non-perturbative CBO Hartree-Fock and coupled cluster theories. Wave
function approaches are reformulated to self-consistently address a cavity
reaction potential (CRP), which minimizes the electronic energy in the cavity
subspace. We derive up to second-order CBO-PT corrections of intra- and
intermolecular energies revealing non-trivial corrections to dipole-dipole,
dipole-induced-dipole and van-der-Waals interactions, and provide analytical
second-order CRP for unimolecular and interacting bimolecular scenarios. In the
unimolecular case, we find small local modifications of molecular PES for
selected isomerization reactions dominantly captured by the first-order dipole
fluctuation. Excellent agreement between CBO-PT and non-perturbative wave
function results is obtained indicating minor VSC-induced state relaxation
effects in the single-molecule limit. In the bimolecular scenario, CBO-PT
reveals an explicit coupling of interacting dimers to cavity modes besides
cavity-polarization dependent dipole-induced-dipole and van-der-Waals
interactions with enhanced long-range character. An illustrative CBO-CCSD-based
numerical analysis of selected molecular dimer models provides a complementary
non-perturbative perspective on cavity-modified intermolecular interactions
under VSC.


  In this Thesis I studied the formation of the four giant planets of the Solar
System in the framework of the nucleated instability hypothesis. The model
considers that solids and gas accretion are coupled in an interactive fashion,
taking into account detailed constitutive physics for the envelope. The
accretion rate of the core corresponds to the oligarchic growth regime. I also
considered that accreted planetesimals follow a size distribution. One of the
main results of this Thesis is that I was able to compute the formation of
Jupiter, Saturn, Uranus and Neptune in less than 10 million years, which is
considered to be the protoplanetary disk mean lifetime.


  The transport of non-thermal particles across a large-scale magnetic field in
the presence of magnetised turbulence has been a long-standing issue in
high-energy astrophysics. Of particular interest is the dependence of the
parallel and perpendicular mean free paths $\lambda_{\parallel}$ and
$\lambda_{\perp}$ on rigidity $\mathcal{R}$. We have revisited this important
issue with a view to applications from the transport of Galactic cosmic rays to
acceleration at astrophysical shocks. We have run test particle simulations of
cosmic ray transport in synthetic, isotropic Kolmogorov turbulence at
unprecedentedly low reduced rigidites $r_g/L_c \simeq 10^{-4}$, corresponding
to $\mathcal{R} \simeq 10 \, \text{TV}$ for a turbulent magnetic field of
$B_{rms} = 4 \, \mu\text{G}$ and correlation length $L_c = 30 \, \text{pc}$.
Extracting the (asymptotic) parallel and perpendicular mean free paths
$\lambda_{\parallel}$ and $\lambda_{\perp}$, we have found $\lambda_{\parallel}
\propto (r_g/L_c)^{1/3}$ as expected for a Kolmogorov turbulence spectrum. In
contrast, $\lambda_{\perp}$ has a faster dependence on $r_g/L_c$ for $10^{-2}
\lesssim r_g/L_c \lesssim 1$, but for $r_g/L_c \ll 10^{-2}$, also
$\lambda_{\perp} \propto (r_g/L_c)^{1/3}$. Our results have important
implications for the transport of Galactic cosmic rays.


  In particle physics, scalar potentials have to be bounded from below in order
for the physics to make sense. The precise expressions of checking lower bound
of scalar potentials are essential, which is an analytical expression of
checking copositivity and positive definiteness of tensors given by such scalar
potentials. Because the tensors given by general scalar potential are 4th order
and symmetric, our work mainly focuses on finding precise expressions to test
copositivity and positive definiteness of 4th order tensors in this paper.
First of all, an analytically sufficient and necessary condition of positive
definiteness is provided for 4th order 2 dimensional symmetric tensors. For 4th
order 3 dimensional symmetric tensors, we give two analytically sufficient
conditions of (strictly) cpositivity by using proof technique of reducing
orders or dimensions of such a tensor. Furthermore, an analytically sufficient
and necessary condition of copositivity is showed for 4th order 2 dimensional
symmetric tensors. We also give several distinctly analytically sufficient
conditions of (strict) copositivity for 4th order 2 dimensional symmetric
tensors. Finally, we apply these results to check lower bound of scalar
potentials, and to present analytical vacuum stability conditions for
potentials of two real scalar fields and the Higgs boson.


  Neutron imaging is an invaluable noninvasive technique for exploring new
science and assisting industrial manufacture. However, state-of-the-art neutron
facilities are extremely expensive and inconvenient to access, while the flux
of portable neutron sources is not strong enough to form even a static image
within an acceptable time frame. It is hard to obtain images with both high
spatial resolution and energy resolution together. Here, based on classical
amplitude modulation, we demonstrate single-pixel imaging with neutrons with
specially designed masks and, further, obtain energy-selective images with a
spallation neutron source. Images of real complex objects with 100 {\mu}m
spatial resolution and 10 {\mu}s time resolution (corresponding to 0.4% at 1
{\AA}) have been obtained using a 3He single-pixel detector. Even when the
neutron counts in the detector plane were lowered to 1000 per modulation
pattern on average, a clear image was still obtained. The experimental setup is
simple, inexpensive and easy to operate, thus our scheme points to a new path
for neutron imaging, especially for portable radioactive neutron sources of low
intensity, which should be of great benefit for diagnostic analysis in biology,
materials science, and industrial processes.


  Two different microscopic phases have been observed via inelastic neutron
scattering for superfluid helium confined within highly monodisperse, smooth,
and unidimensional silica pores. When the helium forms a thin film on the pore
walls, it supports a dramatically modified phonon-roton spectrum as well as a
2D surface roton. The energies of these modified phonon-roton modes are
consistent with predictions for a dilute, low-density film, while the energy of
the 2D surface roton corresponds to that of a dense film. The relatively smooth
and weak surface potential of the substrate permits the formation of a film
with large dilute regions and only small compressed regions. When the pores are
saturated with liquid, the modified phonon-roton spectrum disappears, and
bulk-like modes coexist with the 2D surface roton. Presumably, bulk-like liquid
occupies the core volume of the pores and high density liquid layers are
present at the liquid-solid interface. These findings clearly connect the
nature of the excitations to the local density of the liquid.


  We investigate the ability of basis function expansions to reproduce the
evolution of a Milky Way-like dark matter halo, extracted from a cosmological
zoom-in simulation. For each snapshot, the density of the halo is reduced to a
basis function expansion, with interpolation used to recreate the evolution
between snapshots. The angular variation of the halo density is described by
spherical harmonics, and the radial variation either by biorthonormal basis
functions adapted to handle truncated haloes or by splines. High fidelity orbit
reconstructions are attainable using either method with similar computational
expense. We quantify how the error in the reconstructed orbits varies with
expansion order and snapshot spacing. Despite the many possible biorthonormal
expansions, it is hard to beat a conventional Hernquist-Ostriker expansion with
a moderate number of terms ($\gtrsim15$ radial and $\gtrsim6$ angular). As two
applications of the developed machinery, we assess the impact of the
time-dependence of the potential on (i) the orbits of Milky Way satellites, and
(ii) planes of satellites as observed in the Milky Way and other nearby
galaxies. Time evolution over the last 5 Gyr introduces an uncertainty in the
Milky Way satellites' orbital parameters of $\sim 15$ per cent, comparable to
that induced by the observational errors or the uncertainty in the present-day
Milky Way potential. On average, planes of satellites grow at similar rates in
evolving and time-independent potentials. There can be more, or less, growth in
the plane's thickness, if the plane becomes less, or more, aligned with the
major or minor axis of the evolving halo.


  Shifts from the expected nuclear magnetic resonance frequencies of antimony
and bismuth donors in silicon of greater than a megahertz are observed in
electrically detected magnetic resonance spectra. Defects created by ion
implantation of the donors are discussed as the source of effective electric
field gradients generating these shifts via quadrupole interaction with the
nuclear spins. The experimental results are modeled quantitatively by molecular
orbital theory for a coupled pair consisting of a donor and a spin-dependent
recombination readout center.


  We present results from multifrequency polarimetry of NRAO 140 using the Very
Long Baseline Array. These observations allow us to reveal the distributions of
both the polarization position angle and the Faraday rotation measure (RM).
These distributions are powerful tools to discern the projected and
line-of-sight components of the magnetic field, respectively. We find a
systematic gradient in the RM distribution, with its sign being opposite at
either side of the jet with respect to the jet axis. The sign of the RM changes
only with the direction of the magnetic field component along the line of
sight, so this can be explained by the existence of helical magnetic components
associated with the jet itself. We derive two constraints for the pitch angle
of the helical magnetic field from the distributions of the RM and the
projected magnetic field; the RM distribution indicates that the helical fields
are tightly wound, while that of the projected magnetic field suggests they are
loosely wound around the jet axis. This inconsistency may be explained if the
Faraday rotator is not cospatial with theemitting region. Our results may point
toward a physical picture in which an ultra-relativistic jet (spine) with a
loosely wound helical magnetic field is surrounded by a sub-relativistic wind
layer (sheath) with a tightly wound helical magnetic field.


  Reproducibility has been increasingly encouraged by communities of science in
order to validate experimental conclusions, and replication studies represent a
significant opportunity to vision scientists wishing contribute new perceptual
models, methods, or insights to the visualization community. Unfortunately, the
notion of replication of previous studies does not lend itself to how we
communicate research findings. Simple put, studies that re-conduct and confirm
earlier results do not hold any novelty, a key element to the modern research
publication system. Nevertheless, savvy researchers have discovered ways to
produce replication studies by embedding them into other sufficiently novel
studies. In this position paper, we define three methods -- re-evaluation,
expansion, and specialization -- for embedding a replication study into a novel
published work. Within this context, we provide a non-exhaustive case study on
replications of Cleveland and McGill's seminal work on graphical perception. As
it turns out, numerous replication studies have been carried out based on that
work, which have both confirmed prior findings and shined new light on our
understanding of human perception. Finally, we discuss how publishing a true
replication study should be avoided, while providing suggestions for how vision
scientists and others can still use replication studies as a vehicle to
producing visualization research publications.


  Asteroids and meteorites provide key evidence on the formation of
planetesimals in the Solar System. Asteroids are traditionally thought to form
in a bottom-up process by coagulation within a population of initially km-scale
planetesimals. However, new models challenge this idea by demonstrating that
asteroids of sizes from 100 to 1000 km can form directly from the gravitational
collapse of small particles which have organised themselves in dense filaments
and clusters in the turbulent gas. Particles concentrate passively between
eddies down to the smallest scales of the turbulent gas flow and inside
large-scale pressure bumps and vortices. The streaming instability causes
particles to take an active role in the concentration, by piling up in dense
filaments whose friction on the gas reduces the radial drift compared to that
of isolated particles. In this chapter we review new paradigms for asteroid
formation and compare critically against the observed properties of asteroids
as well as constraints from meteorites. Chondrules of typical sizes from 0.1 to
1 mm are ubiquitous in primitive meteorites and likely represent the primary
building blocks of asteroids. Chondrule-sized particles are nevertheless
tightly coupled to the gas via friction and are therefore hard to concentrate
in large amounts in the turbulent gas. We review recent progress on
understanding the incorporation of chondrules into the asteroids, including
layered accretion models where chondrules are accreted onto asteroids over
millions of years. We highlight in the end ten unsolved questions in asteroid
formation where we expect that progress will be made over the next decade.


  Technological advances are in part enabled by the development of novel
manufacturing processes that give rise to new materials or material property
improvements. Development and evaluation of new manufacturing methodologies is
labor-, time-, and resource-intensive expensive due to complex, poorly defined
relationships between advanced manufacturing process parameters and the
resulting microstructures. In this work, we present a topological
representation of temper (heat-treatment) dependent material micro-structure,
as captured by scanning electron microscopy, called TopTemp. We show that this
topological representation is able to support temper classification of
microstructures in a data limited setting, generalizes well to previously
unseen samples, is robust to image perturbations, and captures domain
interpretable features. The presented work outperforms conventional deep
learning baselines and is a first step towards improving understanding of
process parameters and resulting material properties.


  Forecasting models have been influential in shaping decision-making in the
COVID-19 pandemic. However, there is concern that their predictions may have
been misleading. Here, we dissect the predictions made by four models for the
daily COVID-19 death counts between March 25 and June 5 in New York state, as
well as the predictions of ICU bed utilisation made by the influential IHME
model. We evaluated the accuracy of the point estimates and the accuracy of the
uncertainty estimates of the model predictions. First, we compared the "ground
truth" data sources on daily deaths against which these models were trained.
Three different data sources were used by these models, and these had
substantial differences in recorded daily death counts. Two additional data
sources that we examined also provided different death counts per day. For
accuracy of prediction, all models fared very poorly. Only 10.2% of the
predictions fell within 10% of their training ground truth, irrespective of
distance into the future. For accurate assessment of uncertainty, only one
model matched relatively well the nominal 95% coverage, but that model did not
start predictions until April 16, thus had no impact on early, major decisions.
For ICU bed utilisation, the IHME model was highly inaccurate; the point
estimates only started to match ground truth after the pandemic wave had
started to wane. We conclude that trustworthy models require trustworthy input
data to be trained upon. Moreover, models need to be subjected to prespecified
real time performance tests, before their results are provided to policy makers
and public health officials.


  Recently, a geometric approach to operator mixing in massless QCD-like
theories -- that involves canonical forms based on the Poincare'-Dulac theorem
for the linear system that defines the renormalized mixing matrix in the
coordinate representation $Z(x,\mu)$ -- has been advocated in arXiv:2103.15527
. As a consequence, a classification of operator mixing in four cases --
depending on the canonical forms of $- \frac{\gamma(g)}{\beta(g)}$, with
$\gamma(g)=\gamma_0 g^2+\cdots$ the matrix of the anomalous dimensions and
$\beta(g)=-\beta_0 g^3 + \cdots$ the beta function -- has been proposed: (I)
nonresonant $\frac{\gamma_0}{\beta_0}$ diagonalizable, (II) resonant
$\frac{\gamma_0}{\beta_0}$ diagonalizable, (III) nonresonant
$\frac{\gamma_0}{\beta_0}$ nondiagonalizable, (IV) resonant
$\frac{\gamma_0}{\beta_0}$ nondiagonalizable. In particular, in
arXiv:2103.15527 a detailed analysis of the case (I) -- where operator mixing
reduces to all orders of perturbation theory to the multiplicatively
renormalizable case -- has been provided. In the present paper, following the
aforementioned approach, we work out in the remaining three cases the canonical
forms for $- \frac{\gamma(g)}{\beta(g)}$ to all orders of perturbation theory,
the corresponding UV asymptotics of $Z(x,\mu)$, and the physics interpretation.
We also work out in detail physical realizations of the cases (I) and (II).


  The mid-term fractional frequency stability of miniaturized atomic clocks can
be limited by light-shift effects. In this Letter, we demonstrate the
implementation of a symmetric Auto-Balanced Ramsey (SABR) interrogation
sequence in a microcell-based atomic clock based on coherent population
trapping (CPT). Using this advanced protocol, the sensitivity of the clock
frequency to laser power, microwave power and laser frequency variations is
reduced, at least by one order of magnitude, in comparison with continuous-wave
(CW) or Ramsey interrogation schemes. Light-shift mitigation obtained with the
SABR sequence benefits greatly to the clock Allan deviation for integration
times between 10$^2$ and 10$^5$ s. These results demonstrate that such
interrogation techniques are of interest to enhance timekeeping performances of
chip-scale atomic clocks.


  We present brief review of two probable physical mechanisms that can explain
the results of photometric and spectropolarimetric observations of magnetic
white dwarfs: vacuum polarization effect into a strong magnetic field and,
so-called, magnetic collision induced absorption (magnetic CIA). Both
mechanisms provide observed rotation of polarization ellipse and suppression of
spectral energy distributions. The results of spectropolarimetric observations
of magnetic white dwarfs made at Russian BTA-6m and the results of the near
infrared photometric observations with Russian-Italian AZT-24 telescope located
at Campo Imperatore are also presented.


  The construction of 3D geological models is an essential task in oil/gas
exploration, development and production. However, it is a cumbersome,
time-consuming and error-prone task mainly because of the model's geometric and
topological complexity. The models construction is usually separated into
interpretation and 3D modeling, performed by different highly specialized
individuals, which leads to inconsistencies and intensifies the challenges. In
addition, the creation of models following geological rules is paramount for
properly depicting static and dynamic properties of oil/gas reservoirs. In this
work, we propose a sketch-based approach to expedite the creation of valid 3D
geological models by mimicking how domain experts interpret geological
structures, allowing creating models directly from interpretation sketches. Our
sketch-based modeler (Geo-Sketcher) is based on sketches of standard 2D
topographic and geological maps, comprised of lines, symbols and annotations.
We developed a graph-based representation to enable (1) the automatic
computation of the relative ages of rock series and layers, and (2) the
embedding of specific geological rules directly in the sketching. We introduce
the use of Hermite-Birkhoff Radial Basis Functions to interpolate the
geological map constraints, and demonstrate the capabilities of our approach
with a variety of results with different levels of complexity.


  We re-examine the respective roles played by supernovae (SNe) Types Ia and II
in enriching the intracluster medium (ICM) of galaxy clusters, in light of the
recent downward shift of the ASCA abundance ratios of alpha-elements to iron
favoured by Ishimaru & Arimoto (1997, PASJ, 49, 1). Because of this shift,
Ishimaru & Arimoto conclude that >50% of the ICM iron must have originated from
within Type Ia SNe progenitors. A point not appreciated in their study, nor in
most previous analyses, is the crucial dependence of such a conclusion upon the
adopted massive star physics. Employing several alternative Type II SN yield
compilations, we demonstrate how uncertainties in the treatment of convection
and mass-loss can radically alter our perception of the relative importance of
Type Ia and II SNe as ICM polluters. If mass-loss of the form favoured by
Maeder (1992, A&A, 264, 105) or convection of the form favoured by Arnett
(1996, Supernovae and Nucleosynthesis) is assumed, the effect upon the oxygen
yields would lead us to conclude that Type Ia SNe play no part in polluting the
ICM, in contradiction with Ishimaru & Arimoto. Apparent dichotomies still exist
(e.g. the mean ICM neon-to-iron ratio implies a 100% Type II Fe origin, while
the mean sulphur ratio indicates a 100% Type Ia origin) that cannot be
reconciled with the currently available yield tables.


  We consider inhomogeneous percolation on a hierarchical configuration model
with a heavy-tailed degree distribution. This graph is the configuration model
where all the half-edges are colored either black or white, and edges are
formed by uniformly matching edges of the same color. When only the white
half-edges are paired, we provide sufficient conditions for the size and total
number of incident black half-edges of the connected components to converge in
an $\ell^2$-sense. The limiting vector is described by an $\mathbb{R}^2$-valued
thinned L\'{e}vy process. We also establish an $\ell^2$-limit for the number of
vertices in connected components when a critical proportion of the black edges
are included. A key part of our analysis is establishing a Feller-type property
for the multiplicative coalescent with mass and weight recently studied in
(Dhara et. al 2017, Dhara et. al 2020).


  We investigate the coupling between individual tubes in a rope of single-wall
carbon nanotubes using four probe resistance measurements. By introducing
defects through the controlled sputtering of the rope we generate a strong
non-monotonic temperature dependence of the four terminal resistance. This
behavior reflects the interplay between localization in the intentionally
damaged tubes and coupling to undamaged tubes in the same rope. Using a simple
model we obtain the coherence length and the coupling resistance. The coupling
mechanism is argued to involve direct tunneling between tubes.


  Using the model theory of metric structures, I give an alternative proof of
the following result by Thomas: If the Continuum Hypothesis fails then there
are power of the continuum many universal sofic groups up to isomorphism. This
method is also applicable to universal hyperlinear groups, giving a positive
answer to a question posed by Thomas.


  Higher-order structures of networks, namely, small subgraphs of networks
(also called network motifs), are widely known to be crucial and essential to
the organization of networks. There has been a few work studying the community
detection problem -- a fundamental problem in network analysis, at the level of
motifs. In particular, higher-order spectral clustering has been developed,
where the notion of motif adjacency matrix is introduced as the input of the
algorithm. However, it remains largely unknown that how higher-order spectral
clustering works and when it performs better than its edge-based counterpart.
To elucidate these problems, we investigate higher-order spectral clustering
from a statistical perspective. In particular, we theoretically study the
clustering performance of higher-order spectral clustering under a weighted
stochastic block model and compare the resulting bounds with the corresponding
results of edge-based spectral clustering. It turns out that when the network
is dense with weak signal of weights, higher-order spectral clustering can
really lead to the performance gain in clustering. We also use simulations and
real data experiments to support the findings.


  We define geodesic normal forms for the general series of complex reflection
groups G(e,e,n). This requires the elaboration of a combinatorial technique in
order to explicitly determine minimal word representatives of the elements of
G(e,e,n) over the generating set of the presentation of Corran-Picantin. Using
these geodesic normal forms, we construct intervals in G(e,e,n) that are
lattices. This gives rise to interval Garside groups. We determine which of
these groups are isomorphic to the complex braid group B(e,e,n) and get a
complete classification. For the other Garside groups that appear in our
construction, we provide some of their properties and compute their second
integral homology groups in order to understand these new structures.


  Gaussian Splatting has emerged as a prominent model for constructing 3D
representations from images across diverse domains. However, the efficiency of
the 3D Gaussian Splatting rendering pipeline relies on several simplifications.
Notably, reducing Gaussian to 2D splats with a single view-space depth
introduces popping and blending artifacts during view rotation. Addressing this
issue requires accurate per-pixel depth computation, yet a full per-pixel sort
proves excessively costly compared to a global sort operation. In this paper,
we present a novel hierarchical rasterization approach that systematically
resorts and culls splats with minimal processing overhead. Our software
rasterizer effectively eliminates popping artifacts and view inconsistencies,
as demonstrated through both quantitative and qualitative measurements.
Simultaneously, our method mitigates the potential for cheating view-dependent
effects with popping, ensuring a more authentic representation. Despite the
elimination of cheating, our approach achieves comparable quantitative results
for test images, while increasing the consistency for novel view synthesis in
motion. Due to its design, our hierarchical approach is only 4% slower on
average than the original Gaussian Splatting. Notably, enforcing consistency
enables a reduction in the number of Gaussians by approximately half with
nearly identical quality and view-consistency. Consequently, rendering
performance is nearly doubled, making our approach 1.6x faster than the
original Gaussian Splatting, with a 50% reduction in memory requirements.


  Absence of nearby light sources while capturing an image will degrade the
visibility and quality of the captured image, making computer vision tasks
difficult. In this paper, a color-wise attention network (CWAN) is proposed for
low-light image enhancement based on convolutional neural networks. Motivated
by the human visual system when looking at dark images, CWAN learns an
end-to-end mapping between low-light and enhanced images while searching for
any useful color cues in the low-light image to aid in the color enhancement
process. Once these regions are identified, CWAN attention will be mainly
focused to synthesize these local regions, as well as the global image. Both
quantitative and qualitative experiments on challenging datasets demonstrate
the advantages of our method in comparison with state-of-the-art methods.


  We propose a MAP Bayesian approach to perform and evaluate a co-clustering of
mixed-type data tables. The proposed model infers an optimal segmentation of
all variables then performs a co-clustering by minimizing a Bayesian model
selection cost function. One advantage of this approach is that it is user
parameter-free. Another main advantage is the proposed criterion which gives an
exact measure of the model quality, measured by probability of fitting it to
the data. Continuous optimization of this criterion ensures finding better and
better models while avoiding data over-fitting. The experiments conducted on
real data show the interest of this co-clustering approach in exploratory data
analysis of large data sets.


  We present generalizations of the Newton-Raphson-Simpson method.
Specifically, for a positive integer $m$ and the sequence of coefficients of a
Taylor series of a function $f(z)$, we define an algorithm we denote by
NRS($m$) which is a way to evaluate, in our terminology, a sum of $m$ formal
zeros of $f(z)$. We prove that NRS(1) yields the familiar iterations of the
Newton-Raphson-Simpson method. We also prove that NRS($m$) is way to evaluate
certain $\mathscr{A}$-hypergeometric series defined by Sturmfels. In order to
define these algorithms, we make use of combinatorial objects which we call
trees with negative vertex degree.


  We consider a problem of interference between two independent condensates,
which lack true long range order. We show that their interference pattern
contains information about correlation functions within each condensate. As an
example we analyze the interference between a pair of one dimensional
interacting Bose liquids. We find universal scaling of the average fringe
contrast with system size and temperature that depends only on the Luttinger
parameter. Moreover the full distribution of the fringe contrast, which is also
equivalent to the full counting statistics of the interfering atoms, changes
with interaction strength and lends information on high order correlation
functions. We also demonstrate that the interference between two-dimensional
condensates at finite temperature can be used as a direct probe of the
Kosterlitz-Thouless transition. Finally, we discuss generalization of our
results to describe the intereference of a periodic array of independent
fluctuating condensates.


  A new class of orbital-dependent exchange-correlation (xc) potentials for
applications in noncollinear spin-density-functional theory is developed.
Starting from the optimized effective potential (OEP) formalism for the exact
exchange potential - generalized to the noncollinear case - correlation effects
are added via a self-consistent procedure inspired by the
Singwi-Tosi-Land-Sjolander (STLS) method. The orbital-dependent xc potentials
are applied to the Hubbard dimer in uniform and noncollinear magnetic fields
and compared to exact diagonalization and to the Bethe-ansatz local
spin-density approximation. The STLS gives the overall best performance for
total energies, densities and magnetizations, particularly in the weakly to
moderately correlated regime.


  The concept of realism in quantum mechanics means that results of measurement
are caused by physical variables, hidden or observable. Local hidden variables
were proved unable to explain results of measurements on entangled particles
tested far away from one another. Then, some physicists embraced the idea of
nonlocal hidden variables. The present article proves that this idea is
problematic, that it runs into an impasse vis-\`a-vis the special relativity.


  Based on $k\cdot p$ analysis and realistic tight-binding calculations, we
find that time-reversal-breaking Weyl semimetals can be realized in
magnetically-doped (Mn, Eu, Cr etc.) Sn$_{1-x}$Pb$_x$(Te,Se) class of
topological crystalline insulators. All the Weyl points are well separated in
momentum space and possess nearly the same energy due to high crystalline
symmetry. Moreover, both the Weyl points and Fermi arcs are highly tunable by
varying Pb/Sn composition, pressure, magnetization, temperature, surface
potential etc., opening up the possibility of manipulating Weyl points and
rewiring the Fermi arcs.


  Miniaturization of force probes into nanomechanical oscillators enables
ultrasensitive investigations of forces on dimensions smaller than their
characteristic length scale. Meanwhile it also unravels the force field
vectorial character and how its topology impacts the measurement. Here we
expose an ultrasensitive method to image 2D vectorial force fields by
optomechanically following the bidimensional Brownian motion of a singly
clamped nanowire. This novel approach relies on angular and spectral tomography
of its quasi frequency-degenerated transverse mechanical polarizations:
immersing the nanoresonator in a vectorial force field does not only shift its
eigenfrequencies but also rotate eigenmodes orientation as a nano-compass. This
universal method is employed to map a tunable electrostatic force field whose
spatial gradients can even take precedence over the intrinsic nanowire
properties. Enabling vectorial force fields imaging with demonstrated
sensitivities of attonewton variations over the nanoprobe Brownian trajectory
will have strong impact on scientific exploration at the nanoscale.


  Capillary rise is one of the most well-known capillarity; however, no single
and complete analytic solution has ever been obtained yet. This paper used the
singularity-free equation, and successfully obtained its Taylor's series
solution. The solution revealed that capillary rise dynamics is mainly
controlled by the Bond number and the Galileo number, while the Bond number is
a key parameter within the solution. To avoid the poor rate of convergence of
Taylor's series solution, an approximate analytic solution was proposed, which
was verified numerically.


  Ray tracing on GPUs is becoming quite common these days. There are many
publicly available documents on how to implement basic ray tracing on GPUs for
spheres and implicit surfaces. We even have some general frameworks for ray
tracing on GPUs. We however hardly find details on how to implement more
complex ray tracing algorithms themselves that are commonly used for
photorealistic rendering. This paper explains an implementation of a
stand-alone rendering system on GPUs which supports the bounding volume
hierarchy and stochastic progressive photon mapping. The key characteristic of
the system is that it uses only GLSL shaders without relying on any platform
dependent feature. The system can thus run on many platforms that support
OpenGL, making photorealistic rendering on GPUs widely accessible. This paper
also sketches practical ideas for stackless traversal and pseudorandom number
generation which both fit well with the limited system configuration.


  Memory consistency models (MCMs) specify the legal ordering and visibility of
shared memory accesses in a parallel program. Traditionally, instruction set
architecture (ISA) MCMs assume that relevant program-visible memory ordering
behaviors only result from shared memory interactions that take place between
user-level program instructions. This assumption fails to account for virtual
memory (VM) implementations that may result in additional shared memory
interactions between user-level program instructions and both 1) system-level
operations (e.g., address remappings and translation lookaside buffer
invalidations initiated by system calls) and 2) hardware-level operations
(e.g., hardware page table walks and dirty bit updates) during a user-level
program's execution. These additional shared memory interactions can impact the
observable memory ordering behaviors of user-level programs. Thus, memory
transistency models (MTMs) have been coined as a superset of MCMs to
additionally articulate VM-aware consistency rules. However, no prior work has
enabled formal MTM specifications, nor methods to support their automated
analysis.
  To fill the above gap, this paper presents the TransForm framework. First,
TransForm features an axiomatic vocabulary for formally specifying MTMs.
Second, TransForm includes a synthesis engine to support the automated
generation of litmus tests enhanced with MTM features (i.e., enhanced litmus
tests, or ELTs) when supplied with a TransForm MTM specification. As a case
study, we formally define an estimated MTM for Intel x86 processors, called
x86t_elt, that is based on observations made by an ELT-based evaluation of an
Intel x86 MTM implementation from prior work and available public
documentation. Given x86t_elt and a synthesis bound as input, TransForm's
synthesis engine successfully produces a set of ELTs including relevant ELTs
from prior work.


  Nowadays the development of high-field magnets strongly relies on the
performance of superconducting materials. Iron-based superconductors exhibit
high upper critical fields and low electromagnetic anisotropy, making them
particularly attractive for high-field applications, especially in particle
accelerator magnets, nuclear magnetic resonance spectrometers, medical magnetic
resonance imaging systems and nuclear fusion reactors. Herein, through an
industrially scalable and cost-effective manufacturing strategy, a practical
level critical current density up to 1.1x10^5 A/cm2 at 4.2 K in an external
magnetic field of 10 T was achieved in Cu/Ag composite sheathed Ba0.6K0.4Fe2As2
superconducting tapes. The preparation strategy combines flat rolling to induce
grain texture and a subsequent hot-isostatic-pressing densification. By varying
the parameters of rolling, the degree of grain texture was engineered. It is
found that the transport properties of the Ba1-xKxFe2As2 tapes can be enhanced
by applying a large amount of deformation during rolling, which can be
attributed to the improved degree of c-axis texture. Microstructure
characterizations on the highest-performance tape demonstrate that the
Ba1-xKxFe2As2 phase has a uniform element distribution and small grains with
good connectivity. Grain boundary pinning is consequently enhanced as proved by
large currents circulating through the sample even at 25 K. Our work proves
that Cu/Ag composite sheathed Ba1-xKxFe2As2 superconducting tapes can be a
promising competitor for practical high-field applications in terms of the
viable, scalable and cost-effective fabrication strategy applied and the high
transport properties achieved in this work.


  Synthesizing photo-realistic images from text descriptions is a challenging
problem. Previous studies have shown remarkable progresses on visual quality of
the generated images. In this paper, we consider semantics from the input text
descriptions in helping render photo-realistic images. However, diverse
linguistic expressions pose challenges in extracting consistent semantics even
they depict the same thing. To this end, we propose a novel photo-realistic
text-to-image generation model that implicitly disentangles semantics to both
fulfill the high-level semantic consistency and low-level semantic diversity.
To be specific, we design (1) a Siamese mechanism in the discriminator to learn
consistent high-level semantics, and (2) a visual-semantic embedding strategy
by semantic-conditioned batch normalization to find diverse low-level
semantics. Extensive experiments and ablation studies on CUB and MS-COCO
datasets demonstrate the superiority of the proposed method in comparison to
state-of-the-art methods.


  It is shown that a very simple three-body monopole term can solve practically
all the spectroscopic problems--in the $p$, $sd$ and $pf$ shells--that were
hitherto assumed to need drastic revisions of the realistic potentials.


  In this paper, we study heliospheric Ly-$\alpha$ absorption toward nearby
stars in different lines of sight. We use the Baranov-Malama model of the solar
wind interaction with a two-component (charged component and H atoms)
interstellar medium. Interstellar atoms are described kinetically in the model.
The code allows us to separate the heliospheric absorption into two components,
produced by H atoms originating in the hydrogen wall and heliosheath regions,
respectively. We study the sensitivity of the heliospheric absorption to the
assumed interstellar proton and H atom number densities. These theoretical
results are compared with interstellar absorption toward six nearby stars
observed by the Hubble Space Telescope.


  By monitoring changes in excitonic photoluminescence (PL) that are induced by
terahertz (THz) radiation, we observe resonant THz absorption by
magnetoexcitons in GaAs/AlGaAs quantum wells. Changes in the PL spectrum are
explored as a function of temperature and magnetic field, providing insight
into the mechanisms which allow THz absorption to modulate PL. The strongest
PL-quenching occurs at the heavy hole $1s\to 2p^+$ resonance where heavy hole
excitons are photo-thermally converted into light hole excitons.


  Supernovae, with their diversity of compositions, velocities, envelope
masses, and interactions are good testing grounds for probing the importance of
NLTE in expanding atmospheres. In addition to treating H, He, Li I, O I, Ne I,
Na I, and Mg II in NLTE, we use a very large model atom of Fe II to test the
importance of NLTE processes in both SNe Ia and II. Since the total number of
potential line transitions that one has to include is enormous ($\approx 40$
million), approximations and simplifications are required to treat the problem
accurately and in finite computer time. With our large Fe II model atom (617
levels, 13,675 primary NLTE line transitions) we are able to test several
assumptions for treating the background opacity that are needed to obtain
correct UV line blanketing which determines the shape of near-maximum light
supernova spectra. We find that, due to interactions within the multiplets,
treating the background lines as pure scattering (thermalization parameter
$\epsilon = 0$) is a poor approximation and that an overall mean value of
$\epsilon \sim 0.05 - 0.10 $ is a far better approximation. This is true even
in SNe Ia, where the continuum absorption optical depth at 5000 \AA\ ($\equiv
\tau_{\rm std}$) is $<< 1$. We also demonstrate that a detailed treatment of
NLTE effects is required to properly determine the ionization states of both
abundant and trace elements.


  Using 55 years of daily average temperatures from a local weather station, I
made a least-absolute-deviations (LAD) regression model that accounts for three
effects: seasonal variations, the 11-year solar cycle, and a linear trend. The
model was formulated as a linear programming problem and solved using widely
available optimization software. The solution indicates that temperatures have
gone up by about 2 degrees Fahrenheit over the 55 years covered by the data. It
also correctly identifies the known phase of the solar cycle; i.e., the date of
the last solar minimum. It turns out that the maximum slope of the solar cycle
sinusoid in the regression model is about the same size as the slope produced
by the linear trend. The fact that the solar cycle was correctly extracted by
the model is a strong indicator that effects of this size, in particular the
slope of the linear trend, can be accurately determined from the 55 years of
data analyzed.
  The main purpose for doing this analysis is to demonstrate that it is easy to
find and analyze archived temperature data for oneself. In particular, this
problem makes a good class project for upper-level undergraduate courses in
optimization or in statistics.
  It is worth noting that a similar least-squares model failed to characterize
the solar cycle correctly and hence even though it too indicates that
temperatures have been rising locally, one can be less confident in this
result.
  The paper ends with a section presenting similar results from a few thousand
sites distributed world-wide, some results from a modification of the model
that includes both temperature and humidity, as well as a number of suggestions
for future work and/or ideas for enhancements that could be used as classroom
projects.


  Massive Internet of Things (mIoT) has provided an auspicious opportunity to
build powerful and ubiquitous connections that faces a plethora of new
challenges, where cellular networks are potential solutions due to their high
scalability, reliability, and efficiency. The Random Access CHannel (RACH)
procedure is the first step of connection establishment between IoT devices and
Base Stations (BSs) in the cellular-based mIoT network, where modelling the
interactions between static properties of physical layer network and dynamic
properties of queue evolving in each IoT device are challenging. To tackle
this, we provide a novel traffic-aware spatio-temporal model to analyze RACH in
cellular-based mIoT networks, where the physical layer network is modelled and
analyzed based on stochastic geometry in the spatial domain, and the queue
evolution is analyzed based on probability theory in the time domain. For
performance evaluation, we derive the exact expressions for the preamble
transmission success probabilities of a randomly chosen IoT device with
different RACH schemes in each time slot, which offer insights into
effectiveness of each RACH scheme. Our derived analytical results are verified
by the realistic simulations capturing the evolution of packets in each IoT
device. This mathematical model and analytical framework can be applied to
evaluate the performance of other types of RACH schemes in the cellular-based
networks by simply integrating its preamble transmission principle.


  Some of the accreting X-ray pulsars are reported to exhibit a peculiar
spectral feature at $\sim$10 keV, known as the "10 keV feature". The feature
has been characterized as either an emission line or an absorption line, and
its origin is unknown. It has been found in multiple observations of the same
source by different observatories, but not all the observations of any
particular source consistently showed the presence of it. In this work, we have
carried out a systematic investigation for the presence of the "10 keV feature"
using data from NuSTAR, a low background spectroscopic observatory having
uninterrupted wide band coverage on either side of 10 keV. We performed a
systematic spectral analysis on 58 archival NuSTAR observations of 30 bright
X-ray pulsars. The 3$-$79 keV spectral continua of these selected sources were
fitted with a model chosen on the basis of its fitting quality in 3$-$15 keV
and model simplicity, and then inspected for the presence of the "10 keV
feature". Our analysis indicates the presence of such a feature in 16 out of 58
the NuSTAR observations of 11 different sources and is fitted with a Gaussian
absorption model centered around 10 keV. Our analysis also suggests that such a
feature could be wrongly detected if flare data is not analyzed separately from
persistent emission.