title: Rotating Bullets from A Variable Protostar

abstract:
  We present SMA CO(2-1) observations toward the protostellar jet driven by
SVS13A, a variable protostar in the NGC1333 star-forming region. The SMA
CO(2-1) images show an extremely high-velocity jet composed of a series of
molecular 'bullets'. Based on the SMA CO observations, we discover clear and
large systematic velocity gradients, perpendicular to the jet axis, in the
blueshifted and redshifted bullets. After discussing several alternative
interpretations, such as twin-jets, jet precession, warped disk, and internal
helical shock, we suggest that the systematic velocity gradients observed in
the bullets result from the rotation of the SVS13A jet. From the SMA CO images,
the measured rotation velocities are 11.7-13.7 km/s for the blueshifted bullet
and 4.7+/-0.5 km/s for the redshifted bullet. The estimated specific angular
momenta of the two bullets are comparable to those of dense cores, about 10
times larger than those of protostellar envelopes, and about 20 times larger
than those of circumstellar disks. If the velocity gradients are due to the
rotation of the SVS13A jet, the significant amount of specific angular momenta
of the bullets indicates that the rotation of jets/outflows is a key mechanism
to resolve the so-called 'angular momentum problem' in the field of star
formation. The kinematics of the bullets suggests that the jet launching
footprint on the disk has a radius of about 7.2-7.7 au, which appears to
support the extended disk-wind model. We note that further observations are
needed to comprehensively understand the kinematics of the SVS13A jet, in order
to confirm the rotation nature of the bullets.


title: Basmajian-type identities and Hausdorff dimension of limit sets

abstract:
  In this paper, we study Basmajian-type series identities on holomorphic
families of Cantor sets associated to one-dimensional complex dynamical
systems. We show that the series is absolutely summable if and only if the
Hausdorff dimension of the Cantor set is strictly less than one. Throughout the
domain of convergence, these identities can be analytically continued and they
exhibit nontrivial monodromy.


title: Problem Solving and Learning

abstract:
  One finding of cognitive research is that people do not automatically acquire
usable knowledge by spending lots of time on task. Because students' knowledge
hierarchy is more fragmented, "knowledge chunks" are smaller than those of
experts. The limited capacity of short term memory makes the cognitive load
high during problem solving tasks, leaving few cognitive resources available
for metacognition. The abstract nature of the laws of physics and the chain of
reasoning required to draw meaningful inferences makes these issues critical.
In order to help students, it is crucial to consider the difficulty of a
problem from the perspective of students. We are developing and evaluating
interactive problem-solving tutorials to help students in the introductory
physics courses learn effective problem-solving strategies while solidifying
physics concepts. The self-paced tutorials can provide guidance and support for
a variety of problem solving techniques, and opportunity for knowledge and
skill acquisition.


title: Flag-based Control of Orbit Dynamics in Quantum Lindblad Systems

abstract:
  In this paper, we demonstrate that the dynamics of an $n$-dimensional
Lindblad control system can be separated into its inter- and intra-orbit
dynamics when there is fast controllability. This can be viewed as a control
system on the simplex of density operator spectra, where the flag representing
the eigenspaces is viewed as a control variable. The local controllability
properties of this control system can be analyzed when the control-set of flags
is limited to a finite subset. In particular, there is a natural finite subset
of $n!$ flags that are effective for low-purity orbits.


title: Conformal constraints on defects

abstract:
  In this paper we study the constraints imposed by conformal invariance on
extended objects a.k.a defects in a conformal field theory. We identify a
particularly nice class of defects that is closed under conformal
transformations. Correlation function of the defect with a bulk local operator
is fixed by conformal invariance up to an overall constant. This gives rise to
the notion of defect expansion, where the defect itself is expanded in terms of
local operators. This expansion generalizes the idea of the boundary state. We
will show how one can fix the correlation function of two defects from the
knowledge of the defect expansion. The defect correlator admits a number of
conformal cross-ratios depending on their dimensionality. We find the
differential equation obeyed by the conformal block and solve them in certain
special cases.


title: Asteroseismology of the GW Virginis stars SDSS J0349-0059 and VV 47

abstract:
  We present an asteroseismological study of SDSS J0349-0059 and VV 47 aimed
mainly at deriving their total mass on the basis of state-of-the-art PG 1159
evolutionary models. We compute adiabatic nonradial $g$-mode pulsation periods
for PG 1159 evolutionary models with stellar masses ranging from $0.515$ to
$0.741\ M_{\sun}$, that take into account the complete evolution of the
progenitor stars. We first estimate a mean period spacing for both SDSS
J0349-0059 and VV 47. By comparing the observed period spacing with the
asymptotic period spacing we obtain $M_{\star}\sim 0.569\ M_{\sun}$ for SDSS
J0349-0059 and $M_{\star}\sim 0.523\ M_{\sun}$ for VV 47. If we compare the
observed period spacing with the average of the computed period spacings we
found $M_{\star}\sim 0.535\ M_{\sun}$ for SDSS J0349-0059 and $M_{\star}\sim
0.528 M_{\sun}$ for VV 47. Searching for the best period fit we found, in the
case of SDSS J0349-0059, an asteroseismological model with $M_{\star}= 0.542\
M_{\sun}$ and $T_{\rm eff}= 91\, 255\ $K. For VV 47, we could not find a unique
and unambiguous asteroseismological model. Finally, for SDSS J0349-0059, we
determined the rotation period as being $P_{\rm rot}= 1/\Omega \sim 0.407$
days. The results presented in this work constitute a further step in the study
of GW Vir stars through asteroseismology in the frame of fully evolutionary
models of PG 1159 stars. In particular, once again it is shown the potential of
asteroseismology to derive stellar masses of PG 1159 stars with an
unprecedented precision.


title:
Type Ia Supernova Explosions from Hybrid Carbon-Oxygen-Neon White Dwarf
  Progenitors

abstract:
  Motivated by recent results in stellar evolution that predict the existence
of hybrid white dwarf (WD) stars with a C-O core inside an O-Ne shell, we
simulate thermonuclear (Type Ia) supernovae from these hybrid progenitors. We
use the FLASH code to perform multidimensional simulations in the deflagration
to detonation transition (DDT) explosion paradigm. Our hybrid progenitor models
were produced with the MESA stellar evolution code and include the effects of
the Urca process, and we map the progenitor model to the FLASH grid. We
performed a suite of DDT simulations over a range of ignition conditions
consistent with the progenitor's thermal and convective structure assuming
multiple ignition points. To compare the results from these hybrid WD stars to
previous results from C-O white dwarfs, we construct a set of C-O WD models
with similar properties and similarly simulate a suite of explosions. We find
that despite significant variability within each suite, trends distinguishing
the explosions are apparent in their $^{56}$Ni yields and the kinetic
properties of the ejecta. We comment on the feasibility of these explosions as
the source of some classes of observed subluminous events.


title: Two confirmed class I very low-mass objects in Taurus

abstract:
  [GKH94] 41 and IRAS 04191+1523B were previously identified to be proto-brown
dwarf candidates in Taurus. [GKH94] 41 was classified to be a class I object.
The dereddened spectral energy distribution of the source was later found to be
suggestive of a class II object. IRAS 04191+1523B is a class I object that is
the secondary component of a binary. We determine the evolutionary stage of
[GKH94] 41 and estimate the final masses of the two proto-brown dwarf
candidates. We used archive millimeter observations to produce continuum maps
and collected data from the literature to construct the spectral energy
distribution of the targets. Our continuum maps revealed that both [GKH94] 41
and IRAS 04191+1523B are surrounded by envelopes. This provides direct evidence
that [GKH94] 41 is a class I object, not class II, as previously classified.
For IRAS 04191+1523B, our continuum map spatially resolved the binary. Our
estimated final masses are below 49$^{+56}_{-27}$ $M_{\rm J}$ and
75$^{+40}_{-26}$ $M_{\rm J}$ for [GKH94] 41 and IRAS 04191+1523B, respectively.
This indicates that both sources will likely become brown dwarfs or very
low-mass stars. Therefore, [GKH94] 41 and IRAS 04191+1523B are two new
confirmed class I very low-mass objects. Their existence also supports the
scenario that brown dwarfs have the same formation stages as low-mass stars.


title: Helium Stars: Towards an Understanding of Wolf-Rayet Evolution

abstract:
  Wolf-Rayet (WR) stars are massive stars that have lost most or all of their
hydrogen via powerful stellar winds. Recent observations have indicated that
hydrogen-free WR stars have cooler temperatures than those predicted by current
evolutionary models. To investigate how varying mass-loss rate affects WR
evolution, we have created a grid of pure helium star models. We compare our
results with Galactic and LMC WR observations and show that the temperature
ranges of observed WR stars can be reproduced by varying the mass-loss rate,
which effectively determines the size of the helium envelope around the core.
We also find that WN and WO stars arise from more massive stars, whereas WC
stars come from lower masses. This contradicts the standard Conti scenario by
which WN and WC stars evolve in an age sequence. We also predict the magnitudes
of our models at core-collapse and compare with observations of nearby
progenitors of Type Ib/c supernovae. We confirm the findings of previous
studies that suggest WR stars are the progenitors of core-collapse supernovae:
the progenitors would remain unobserved except in the cases where the
progenitor is a low-mass helium giant, as is the case of iPTF13bvn.


title: Text Matching as Image Recognition

abstract:
  Matching two texts is a fundamental problem in many natural language
processing tasks. An effective way is to extract meaningful matching patterns
from words, phrases, and sentences to produce the matching score. Inspired by
the success of convolutional neural network in image recognition, where neurons
can capture many complicated patterns based on the extracted elementary visual
patterns such as oriented edges and corners, we propose to model text matching
as the problem of image recognition. Firstly, a matching matrix whose entries
represent the similarities between words is constructed and viewed as an image.
Then a convolutional neural network is utilized to capture rich matching
patterns in a layer-by-layer way. We show that by resembling the compositional
hierarchies of patterns in image recognition, our model can successfully
identify salient signals such as n-gram and n-term matchings. Experimental
results demonstrate its superiority against the baselines.


title:
The spin-3/2 Blume-Capel model with competing short- and long-range
  interactions

abstract:
  The phase diagrams of the spin-$3/2$ Blume-Capel model with competing short
and long-range interactions were studied through the free energy density
obtained by analytical methods. The competition emerges when positive
short-range interactions of strength $K$ arranged in a linear chain tend to
establish an anti-parallel spin order, whereas negative long-range interactions
$-J$ tend to align them in parallel. Thus, no ferromagnetic order exists for
$K/J > 0.25$. So, the phase-diagrams were scanned by varying the values of $K$
in this interval. As in other similar study done for the spin-1 case, the
second-order frontier separating the ferromagnetic and the paramagnetic phases
is transformed gradually into a first-order line, when $K/J$ is greater than a
certain critical value. Accordingly, there is a subinterval of $K$, for which
two tricritical points appear restricting the length of the second-order
frontier. Nevertheless, for greater values of $K/J$, the
ferromagnetic-paramagnetic frontier becomes wholly of first order. Also, the
tipical coexistence line, which divides two different ferromagnetic phases of
magnetization $m=3/2$ and $m=1/2$, becomes more complex by giving rise to
another line of coexistence with a reentrant behavior that encloses a third
ordered phase. In this case, the competition is such that there is a region in
the phase diagram, where for each spin $i$ with $S_{i}=3/2$ ($S_{i}=-3/2$),
there is another one spin $j$ with $S_{j}=-1/2$ ($S_{j}=1/2$), so the absolute
value of the magnetization per spin is one.


title: Centripetal Acceleration: Often Forgotten or Misinterpreted

abstract:
  Acceleration is a fundamental concept in physics which is taught in mechanics
at all levels. Here, we discuss some challenges in teaching this concept
effectively when the path along which the object is moving has a curvature and
centripetal acceleration is present. We discuss examples illustrating that both
physics teachers and students have difficulty with this concept. We conclude
with instructional strategies that may help students with this challenging
concept.


title: Time independent quantum circuits with local interactions

abstract:
  Heisenberg spin chains can act as quantum wires transferring quantum states
either perfectly or with high fidelity. Gaussian packets of excitations passing
through dual rails can encode the two states of a logical qubit, depending on
which rail is empty and which rail is carrying the packet. With extra
interactions in one or between different chains, one can introduce interaction
zones in arrays of such chains, where specific one or two qubit gates act on
any qubit which passes through these interaction zones. Therefore universal
quantum computation is made possible in a static way where no external control
is needed. This scheme will then pave the way for a scalable way of quantum
computation where specific hardwares can be connected to make large quantum
circuits. Our scheme is an improvement of a recent scheme where we have
achieved to borrow an idea from quantum electrodynamics to replace non-local
interactions between spin chains with local interactions mediated by an
ancillary chain.


title:
Solving the Strong CP Problem with High-Colour Quarks and Composite
  Axion

abstract:
  I propose a new axionic solution to the strong CP problem which involves a
hypothetical vector-like quark(s) in a high-colour representation of the
conventional QCD. There are two distinct scenarios. If the current mass of the
exotic quark is zero, the strong CP phase can be trivially rotated away. The
high-colour quark is `hidden' in various bounds states, the lightest being the
composite axion field, with properties similar to the standard invisible axion.
If the high-colour quark acquire a non-zero current mass due to the spontaneous
chiral symmetry breaking, the composite axion can be heavy, while the strong CP
phase is still cancelling out in the vacuum. The phenomenology and cosmological
implications of the heavy composite axion differs drastically from the standard
invisible axion.


title:
Isotropic Brownian motions over complex fields as a solvable model for
  May-Wigner stability analysis

abstract:
  We consider matrix-valued stochastic processes known as isotropic Brownian
motions, and show that these can be solved exactly over complex fields. While
these processes appear in a variety of questions in mathematical physics, our
main motivation is their relation to a May-Wigner-like stability analysis, for
which we obtain a stability phase diagram. The exact results establish the full
joint probability distribution of the finite-time Lyapunov exponents, and may
be used as a starting point for a more detailed analysis of the
stability-instability phase transition. Our derivations rest on an explicit
formulation of a Fokker-Planck equation for the Lyapunov exponents. This
formulation happens to coincide with an exactly solvable class of models of the
Calgero-Sutherland type, originally encountered for a model of phase-coherent
transport. The exact solution over complex fields describes a determinantal
point process of biorthogonal type similar to recent results for products of
random matrices, and is also closely related to Hermitian matrix models with an
external source.

categories: math-ph cond-mat.dis-nn cond-mat.stat-mech math.MP


title:
Distributed Power Control in Interference Channels with QoS Constraints
  and RF Energy Harvesting: A Game-Theoretic Approach

abstract:
  This paper develops a new distributed power control scheme for a power
splitting-based interference channel (IFC) with simultaneous wireless
information and power transfer (SWIPT). The considered IFC consists of multiple
source-destination pairs. Each destination splits its received signal into two
parts for information decoding and energy harvesting (EH), respectively. Each
pair adjusts its transmit power and power splitting ratio to meet both the
signal-to-interference-plus-noise ratio (SINR) and EH constraints at its
corresponding destination. To characterize rational behaviors of
source-destination pairs, we formulate a non-cooperative game for the
considered system, where each pair is modeled as a strategic player who aims to
minimize its own transmit power under both SINR and EH constraints at the
destination. We derive a sufficient and necessary condition for the existence
and uniqueness of the Nash equilibrium (NE) of the formulated game. The best
response strategy of each player is derived and then the NE can be achieved
iteratively. Numerical results show that the proposed game-theoretic approach
can achieve a near-optimal performance under various SINR and EH constraints.


title: Robust Estimation of Propensity Score Weights via Subclassification

abstract:
  Weighting estimators based on propensity scores are widely used for causal
estimation in a variety of contexts, such as observational studies, marginal
structural models and interference. They enjoy appealing theoretical properties
such as consistency and possible efficiency under correct model specification.
However, this theoretical appeal may be diminished in practice by sensitivity
to misspecification of the propensity score model. To improve on this, we
borrow an idea from an alternative approach to causal effect estimation in
observational studies, namely subclassification estimators. It is well known
that compared to weighting estimators, subclassification methods are usually
more robust to model misspecification. In this paper, we first discuss an
intrinsic connection between the seemingly unrelated weighting and
subclassification estimators, and then use this connection to construct robust
propensity score weights via subclassification. We illustrate this idea by
proposing so-called full-classification weights and accompanying estimators for
causal effect estimation in observational studies. Our novel estimators are
both consistent and robust to model misspecification, thereby combining the
strengths of traditional weighting and subclassification estimators for causal
effect estimation from observational studies. Numerical studies show that the
proposed estimators perform favorably compared to existing methods.


title:
Improving Students' Understanding of Quantum Mechanics via the
  Stern-Gerlach Experiment

abstract:
  The Stern-Gerlach experiment has played a central role in the discovery of
spin angular momentum. It can also play a pivotal role in teaching the
formalism of quantum mechanics using a concrete example involving a
finite-dimensional Hilbert space. Using this context, students can learn about
how to prepare a specific quantum state starting from an arbitrary state,
issues related to the time evolution of the wave function, and quantum
measurement. It can also be exploited to teach students about the distinction
between the physical space where one performs the experiment and the Hilbert
space where the state of the system lies and how the information about the
state of the system in the Hilbert space can be exploited to interpret the
possible outcomes of the experiment in the physical space. Students can learn
the advantages of choosing an appropriate basis to make suitable predictions
about the outcomes of experiments with different arrangements of Stern-Gerlach
devices. This experiment can also help students understand that an ensemble of
identically prepared systems, e.g., one in a linear superposition of two
stationary states, is not the same as a mixture, e.g., in which half of the
systems are in one stationary state and the other half are in the other
stationary state. Here, we discuss investigation of students' difficulties
about the Stern-Gerlach experiment by giving written tests and interviewing
advanced undergraduate and graduate students in quantum mechanics courses. We
also discuss preliminary data from two quantum mechanics courses that suggest
that a Quantum Interactive Learning Tutorial (QuILT) related to the
Stern-Gerlach experiment is helpful in improving students' understanding of
these concepts.


title:
Modeling and stabilization results for a charge or current-actuated
  active constrained layer (ACL) beam model with the electrostatic assumption

abstract:
  An infinite dimensional model for a three-layer active constrained layer
(ACL) beam model, consisting of a piezoelectric elastic layer at the top and an
elastic host layer at the bottom constraining a viscoelastic layer in the
middle, is obtained for clamped-free boundary conditions by using a thorough
variational approach. The Rao-Nakra thin compliant layer approximation is
adopted to model the sandwich structure, and the electrostatic approach
(magnetic effects are ignored) is assumed for the piezoelectric layer. Instead
of the voltage actuation of the piezoelectric layer, the piezoelectric layer is
proposed to be activated by a charge (or current) source. We show that, the
closed-loop system with all mechanical feedback is shown to be uniformly
exponentially stable. Our result is the outcome of the compact perturbation
argument and a unique continuation result for the spectral problem which relies
on the multipliers method. Finally, the modeling methodology of the paper is
generalized to the multilayer ACL beams, and the uniform exponential
stabilizability result is established analogously.


title: Improving Student Understanding of Coulomb's Law and Gauss's Law

abstract:
  We discuss the development and evaluation of five research-based tutorials on
Coulomb's law, superposition, symmetry and Gauss's Law to help students in the
calculus-based introductory physics courses learn these concepts. We discuss
the performance of students on the pre-/post-tests given before and after the
tutorials in three calculus-based introductory physics courses. We also discuss
the performance of students who used the tutorials and those who did not use it
on a multiple-choice test which employs concepts covered in the tutorials.


title:
Oscillation of Newly Formed Loops After Magnetic Reconnection in the
  Solar Chromosphere

abstract:
  With the high spatial and temporal resolution H$\alpha$ images from the New
Vacuum Solar Telescope, we focus on two groups of loops with a X-shaped
configuration in the dynamic chromosphere. We find that the anti-directed loops
approach each other and reconnect continually. The connectivity of the loops is
changed and new loops are formed and stack together. The stacked loops are
sharply bent, implying that they are greatly impacted by the magnetic tension
force. When another more reconnection process takes place, one new loop is
formed and stacks with the previously formed ones. Meanwhile, the stacked loops
retract suddenly and move toward the balance position, performing an overshoot
movement, which led to an oscillation with an average period of about 45 s. The
oscillation of newly formed loops after magnetic reconnection in the
chromosphere is observed for the first time. We suggest that the stability of
the stacked loops is destroyed due to the join of the last new loop and then
suddenly retract under the effect of magnetic tension. Because of the
retraction, another lower loop is pushed outward and performs an oscillation
with the period of about 25 s. The different oscillation periods may be due to
their difference in three parameters, i.e., loop length, plasma density, and
magnetic field strength.


title:
Demonstration of quantum synchronization based on second-order quantum
  coherence of entangled photons

abstract:
  Based on the second-order quantum interference between frequency entangled
photons that are generated by parametric down conversion, a quantum strategic
algorithm for synchronizing two spatially separated clocks has been recently
presented. In the reference frame of a Hong-Ou-Mandel (HOM) interferometer,
photon correlations are used to define simultaneous events. Once the HOM
interferometer is balanced by use of an adjustable optical delay in one arm,
arrival times of simultaneously generated photons are recorded by each clock.
The clock offset is determined by correlation measurement of the recorded
arrival times. Utilizing this algorithm, we demonstrate a proof-of-principle
experiment for synchronizing two clocks separated by 4km fiber link. A minimum
timing stability of 0.4 ps at averaging time of 16000 s is achieved with an
absolute time accuracy of 59.4 ps. The timing stability is verified to be
limited by the correlation measurement device and ideally can be better than 10
fs. Such results shine a light to the application of quantum clock
synchronization in the real high-accuracy timing system.


title: Convex Polygons for Aperiodic Tiling

abstract:
  If all tiles in a tiling are congruent, the tiling is called monohedral.
Tiling by convex polygons is called edge-to-edge if any two convex polygons are
either disjoint or share one vertex or one entire edge in common. In this
paper, we prove that a convex polygon that can generate an edge-to-edge
monohedral tiling must be able to generate a periodic tiling.


title:
Cross Validation in Compressive Sensing and its Application of OMP-CV
  Algorithm

abstract:
  Compressive sensing (CS) is a data acquisition technique that measures sparse
or compressible signals at a sampling rate lower than their Nyquist rate.
Results show that sparse signals can be reconstructed using greedy algorithms,
often requiring prior knowledge such as the signal sparsity or the noise level.
As a substitute to prior knowledge, cross validation (CV), a statistical method
that examines whether a model overfits its data, has been proposed to determine
the stopping condition of greedy algorithms. This paper first analyzes cross
validation in a general compressive sensing framework and developed general
cross validation techniques which could be used to understand CV-based sparse
recovery algorithms. Furthermore, we provide theoretical analysis for OMP-CV, a
cross validation modification of orthogonal matching pursuit, which has very
good sparse recovery performance. Finally, numerical experiments are given to
validate our theoretical results and investigate the behaviors of OMP-CV.


title: Students' Understanding of Stern Gerlach Experiment

abstract:
  The Stern Gerlach experiment has played a central role in the discovery of
spin angular momentum and it has also played a pivotal role in elucidating
foundational issues in quantum mechanics. Here, we discuss investigation of
students' difficulties related to the Stern Gerlach experiment by giving
written tests and interviewing advanced undergraduate and graduate students in
quantum mechanics. We also discuss preliminary data that suggest that the
Quantum Interactive Learning Tutorial (QuILT) related to the Stern Gerlach
experiment is helpful in improving students' understanding of these concepts.


title: Power-Distortion Metrics for Path Planning over Gaussian Sensor Networks

abstract:
  Path planning is an important component of au- tonomous mobile sensing
systems. This paper studies upper and lower bounds of communication performance
over Gaussian sen- sor networks, to drive power-distortion metrics for path
planning problems. The Gaussian multiple-access channel is employed as a
channel model and two source models are considered. In the first setting, the
underlying source is estimated with minimum mean squared error, while in the
second, reconstruction of a random spatial field is considered. For both
problem settings, the upper and the lower bounds of sensor power-distortion
curve are derived. For both settings, the upper bounds follow from the
amplify-and-forward scheme and the lower bounds admit a unified derivation
based on data processing inequality and tensorization property of the maximal
correlation measure. Next, closed-form solutions of the optimal power
allocation problems are obtained under a weighted sum-power constraint. The gap
between the upper and the lower bounds is analyzed for both weighted sum and
individual power constrained settings. Finally, these metrics are used to drive
a path planning algorithm and the effects of power-distortion metrics, network
parameters, and power optimization on the optimized path selection are
analyzed.


title: Movement of time-delayed hot spots in Euclidean space

abstract:
  We investigate the shape of the solution of the Cauchy problem for the damped
wave equation. In particular, we study the existence, location and number of
spatial maximizers of the solution. Studying the shape of the solution of the
damped wave equation, we prepare a decomposed form of the solution into the
heat part and the wave part. Moreover, as its another application, we give
$L^p$-$L^q$ estimates of the solution.


title:
Test of the universality of free fall with atoms in different spin
  orientations

abstract:
  We report a test of the universality of free fall (UFF) by comparing the
gravity acceleration of the $^{87}$Rb atoms in $m_F=+1$ versus that in
$m_F=-1$, where the corresponding spin orientations are opposite. A
Mach-Zehnder-type atom interferometer is exploited to sequentially measure the
free fall acceleration of the atoms in these two magnetic sublevels, and the
resultant E$\rm{\ddot{o}}$tv$\rm{\ddot{o}}$s ratio is ${\eta _S}
=(0.2\pm1.2)\times 10^{-7}$. This also gives an upper limit of $1.1\times
10^{-21}$ GeV/m for possible gradient field of the spacetime torsion. The
interferometer using atoms in $m_F=\pm 1$ is highly sensitive to the magnetic
field inhomogeneity, and a double differential measurement method is developed
to alleviate the inhomogeneity influence. Moreover, a proof experiment by
modulating the magnetic field is performed, which validates the alleviation of
the inhomogeneity influence in our test.


title:
Understanding the negative binomial multiplicity fluctuations in
  relativistic heavy ion collisions

abstract:
  By deriving a general expression for multiplicity distribution (a conditional
probability distribution) in statistical model, we demonstrate the mismatches
between experimental measurements and previous theoretical calculations on
multiplicity fluctuations. From the corrected formula, we develop an improved
baseline measure for multiplicity distribution under Poisson approximation in
statistical model to replace the traditional Poisson expectations. We find that
the ratio of the mean multiplicity to the corresponding reference multiplicity
are crucial to systemically explaining the measured scale variances of total
charge distributions in different experiments, as well as understanding the
centrality resolution effect observed in experiment. The improved statistical
expectations, albeit simple, work well in describing the negative binomial
multiplicity distribution measured in experiments, e.g. the cumulants (cumulant
products) of total (net) electric charge distributions.


title:
First-forbidden transitions and stellar $\beta$-decay rates of Zn and Ge
  isotopes

abstract:
  First-forbidden (FF) charge-changing transitions become relatively important
for nuclei as their proton number increases. This is because the strength of
allowed Gamow-Teller (GT) transitions decreases with increasing Z. The FF
transitions play an important role in reducing the half-lives as against those
calculated from taking the GT transitions alone into account. In this paper we
calculate allowed GT as well as $0^{+} \rightarrow 0^{-}$ and $0^{+}
\rightarrow 2^{-}$ transitions for neutron-rich Zn and Ge isotopes. Two
different pn-QRPA models were used with a schematic separable interaction to
calculate GT and FF transitions. Half-lives calculated after inclusion of FF
transitions were in excellent agreement with the experimental data. Our
calculations were also compared to previous QRPA calculations and were found to
be in better agreement with measured data. Stellar $\beta$-decay rates were
calculated for these nuclei including allowed GT and unique FF transitions for
astrophysical applications. $^{86,88}$Ge has a sizeable contribution to the
total stellar rate from unique FF transitions.


title:
Note: a counterexample to a conjecture of Jackson about hamiltonicity of
  diregular digraphs

abstract:
  $3$-diregular circulant digraph on $12$ vertices is a counterexample of
Jackson's conjecture about hamiltonicity of diregular digraphs


title:
First-forbidden $\mathbf{\beta}$-decay rates, energy rates of
  $\beta$-delayed neutrons and probability of $\beta$-delayed neutron emissions
  for neutron-rich nickel isotopes

abstract:
  First-forbidden (FF) transitions can play an important role in decreasing the
calculated half-lives specially in environments where allowed Gamow-Teller (GT)
transitions are unfavored. Of special mention is the case of neutron-rich
nuclei where, due to phase-space amplification, FF transitions are much
favored. We calculate the allowed GT transitions in various pn-QRPA models for
even-even neutron-rich isotopes of nickel. Here we also study the effect of
deformation on the calculated GT strengths. The FF transitions for even-even
neutron-rich isotopes of nickel are calculated assuming the nuclei to be
spherical. Later we take into account deformation of nuclei and calculate GT +
unique FF transitions, stellar $\beta$-decay rates, energy rate of
$\beta$-delayed neutrons and probability of $\beta$-delayed neutron emissions.
The calculated half-lives are in excellent agreement with measured ones and
might contribute in speeding-up of the $r$-matter flow.


title: Synchronization of two couple pendula in absence of escapement

abstract:
  A model of two oscillating pendula placed on a mobile support is studied.
Once an overall scheme of equations, under general assumptions, is formulated
via the Lagrangian equations of motion, the specific case of absence of
escapement is examined. The mechanical models consists of two coupled pendula
both oscillating on a moving board attached to a spring. The final result
performs a selection among the peculiar parameters of the physical process
(lenghts, ratio of masses, friction and damping coefficients, stiffness of the
spring) which provide a tendency to synchronization.


title:
Testing hypotheses about mixture distributions using not identically
  distributed data

abstract:
  Testing hypotheses of goodness-of-fit about mixture distributions on the
basis of independent but not necessarily identically distributed random vectors
is considered. The hypotheses are given by a specific distribution or by a
family of distributions. Moreover, testing hypotheses formulated by Hadamard
differentiable functionals is discussed in this situation, in particular the
hypothesis of central symmetry, homogeneity and independence.
Kolmogorov-Smirnov or Cram\'er-von-Mises type statistics are suggested as well
as methods to determine critical values. The focus of the investigation is on
asymptotic properties of the test statistics. Further, outcomes of simulations
for finite sample sizes are given. Applications to models with not identically
distributed errors are presented. The results imply that the tests are of
asymptotically exact size and consistent.


title: Excited State Mass spectra of Singly Charmed Baryons

abstract:
  Mass spectra of excited states of the singly charmed baryons are calculated
using the hypercentral description of three body system. The baryon consist of
a charm quark and light quarks (u, d and s) are studied in the framework of QCD
motivated constituent quark model. The form of confinement potential is hyper
coloumb plus power potential with potential index $\nu$, varying from 0.5 to
2.0. The first order correction to the confinement potential is also
incorporated in this approach. The radial as well as orbital excited state
masses of $\Sigma_{c}^{++}, \Sigma_{c}^+, \Sigma_{c}^0, \Xi_c^+, \Xi_c^0,
\Lambda_c^+, \Omega_c^0$ baryons, are reported in this paper. We have
incorporated spin-spin, spin-orbit and tensor interactions perturbatively in
the present study. The semi-electronic decay of $\Omega_c$ and $\Xi_c$ are also
calculated using the spectroscopic parameters of these baryons. The computed
results are compared with other theoretical predictions as well as with the
available experimental observations. We also construct the Regge trajectory in
($n_r$, $M^{2}$) and (J, $M^{2}$) plane for these baryons.


title:
Gamow-Teller strength distributions and neutrino energy loss rates due
  to chromium isotopes in stellar matter

abstract:
  Gamow-Teller transitions in isotopes of chromium play a consequential role in
the presupernova evolution of massive stars. $\beta$-decay and electron capture
rates on chromium isotopes significantly affect the time rate of change of
lepton fraction ($\dot{Y_{e}}$). Fine-tuning of this parameter is one of the
key for simulating a successful supernova explosion. The (anti)neutrinos
produced as a result of electron capture and $\beta$-decay are transparent to
stellar matter during presupernova phases. They carry away energy and this
result in cooling the stellar core. In this paper we present the calculations
of Gamow-Teller strength distributions and (anti)neutrino energy loss rates due
to weak interactions on chromium isotopes of astrophysical importance. We
compare our results with measured data and previous calculations wherever
available.


title:
Reachable sheaves on ribbons and deformations of moduli spaces of
  sheaves

abstract:
  A primitive multiple curve is a Cohen-Macaulay irreducible projective curve Y
that can be locally embedded in a smooth surface, and such that C=Y_red is
smooth. In this case, L=I_C/I_C^2 is a line bundle on C. If Y is of
multiplicity 2, i.e. if I_C^2=0, Y is called a ribbon. If Y is a ribbon and
h^0(L^{-2})>0, then Y can be deformed to smooth curves, but in general a
coherent sheaf on Y cannot be deformed in coherent sheaves on the smooth
curves.
  A ribbon with associated line bundle L such that deg(L)=-d<0 can be deformed
to reduced curves having 2 irreducible components if L can be written as
L=O_C(-P1-...-Pd)$, where P1,...,P_d are distinct points of C. In this case we
prove that quasi locally free sheaves on Y can be deformed to torsion free
sheaves on the reducible curves with two components. This has some consequences
on the structure and deformations of the moduli spaces of semi-stable sheaves
on Y.


title:
Gamow-Teller (GT$\pm$) strength distributions of $^{56}Ni$ for ground
  and excited states

abstract:
  Gamow-Teller (GT) transitions play an important and consequential role in
many astrophysical phenomena. These include, but are not limited to, electron
and positron capture rates which determine the fate of massive stars and play
an intricate role in the dynamics of core collapse. These $GT_{\pm}$
transitions rates are the significant inputs in the description of supernova
explosions. $GT_{\pm}$ strength function values are sensitive to the $^{56}Ni$
core excitation in the middle \textit{pf}-shell region and to the size of the
model space as well. We used the pn-QRPA theory for extracting the GT strength
for ground and excited states of $^{56}Ni$. We then used these GT strength
distributions to calculate the electron \textit{and} positron capture rates
which show differences with the earlier calculations. One curious finding of
this paper is our enhanced electron capture rates on $^{56}Ni$ at presupernova
temperatures. These differences need to be taken into account for the modeling
of the early stages of Type II supernova evolution.


title: Using Analogies to Learn Introductory Physics

abstract:
  Identifying the relevant physics principles is a central component of problem
solving. A major goal of most introductory physics courses is to help students
discern the deep similarities between problems based upon the physics
principles so that they can transfer what they learned by solving one problem
to solve another problem which involves the same principle. We conducted an
investigation in which 251 calculus- and algebra-based introductory physics
students were asked explicitly in the recitation quiz to learn from a solved
problem and then solve another problem that has different surface features but
the same underlying physics principles. We find that many students were able to
discern the deep similarities between the problems. When the solved problem was
provided, students were likely to invoke the correct principles; however, more
scaffolding is needed to help students apply these principles correctly.


title: Using Analogy to Solve a Three-Step Physics Problem

abstract:
  In a companion paper, we discuss students' ability to take advantage of what
they learn from a solved problem and transfer their learning to solve a quiz
problem that has different surface features but the same underlying physics
principles. Here, we discuss students' ability to perform analogical reasoning
between another pair of problems. Both the problems can be solved using the
same physics principles. However, the solved problem provided was a two- step
problem (which can be solved by decomposing it into two sub-problems) while the
quiz problem was a three-step problem. We find that it is challenging for
students to extend what they learned from a two-step problem to solve a
three-step problem.


title:
Using Analogical Problem Solving with Different Scaffolding Supports to
  Learn about Friction

abstract:
  Prior research suggests that many students believe that the magnitude of the
static frictional force is always equal to its maximum value. Here, we examine
introductory students' ability to learn from analogical reasoning (with
different scaffolding supports provided) between two problems that are similar
in terms of the physics principle involved but one problem involves static
friction, which often triggers the misleading notion. To help students process
through the analogy deeply and contemplate whether the static frictional force
was at its maximum value, students in different recitation classrooms received
different scaffolding support. We discuss students' performance in different
groups.


title:
The group administered interactive questionnaire: An alternative to
  individual interviews

abstract:
  Individual interviews are often considered to be the gold standard for
researchers to understand how people think about phenomena. However, conducting
and analyzing interviews is very time consuming. This paper presents the Group
Administered Interactive Questionnaire (GAIQ) as an alternative to individual
interviews and discusses the pros and cons of each data collection method. Use
of GAIQ will be discussed in the context of a study that seeks to understand
teaching assistants' reasons for the design of problem solutions for
introductory physics.


title: TA-designed vs. research-oriented problem solutions

abstract:
  In order to study graduate teaching assistants (TAs) beliefs and values about
the design of instructor problem solutions, twenty-four TAs were provided with
different solutions and asked to discuss their preferences for prominent
solution features. TAs preferences for solution features were examined in light
of the modeling of expert-like problem solving process as recommended in the
literature. Results suggest that while many of the features TAs valued align
with expert-like problem solving approaches, they noticed primarily "surface
features" of solutions. Moreover, self-reported preferences did not match well
with the solutions TAs wrote on their own.


title: On presymplectic structures for massless higher-spin fields

abstract:
  A natural presymplectic structure for non-Lagrangian equations of motion
governing the dynamics of free higher-spin fields in four-dimensional anti-de
Sitter space is proposed. This presymplectic structure is then used to the
derivation of the conserved currents associated with the relativistic
invariance and to the construction of local functionals of fields that are
gauge invariant on shell.


title: Ooid growth: Uniqueness of time-invariant, smooth shapes in 2D

abstract:
  Evolution of planar curves under a nonlocal geometric equation is
investigated. It models the simultaneous contraction and growth of carbonate
particles called ooids in geosciences. Using classical ODE results and a
bijective mapping we demonstrate that the steady parameters associated with the
physical environment determine a unique, time-invariant, compact shape among
smooth, convex curves embedded in $R^2$. It is also revealed that any
time-invariant solution possesses $D_2$ symmetry. The model predictions
remarkably agree with ooid shapes observed in nature.


title: Computing halting probabilities from other halting probabilities

abstract:
  The halting probability of a Turing machine is the probability that the
machine will halt if it starts with a random stream written on its one-way
input tape. When the machine is universal, this probability is referred to as
Chaitin's omega number, and is the most well known example of a real which is
random in the sense of Martin-L\"{o}f. Although omega numbers depend on the
underlying universal Turing machine, they are robust in the sense that they all
have the same Turing degree, namely the degree of the halting problem. In this
paper we give precise bounds on the redundancy growth rate that is generally
required for the computation of an omega number from another omega number. We
show that for each $\epsilon >1$, any pair of omega numbers compute each other
with redundancy $\epsilon \log n$. On the other hand, this is not true for
$\epsilon=1$. In fact, we show that for each omega number there exists another
omega number which is not computable from the first one with redundancy $\log
n$. This latter result improves an older result of Frank Stephan.


title:
Effect of disorder on the dimer transition of the honeycomb-lattice
  compound Li$_{2}$RuO$_3$

abstract:
  We report the dependence of magnetic properties on the crystalline disorder
in Li$_{2}$RuO$_3$ with Ru honeycomb lattice. This oxide exhibits
unconventional Ru-dimer transition below $T_\text{d} \sim$ 540 K. We
demonstrate that the cell parameters, related to the coherence of the dimer
formation, are strongly dependent on the synthesis procedure. We show that the
magnetic behavior at the dimer transition is closely related to the lattice
parameters. In particular, we revealed that samples with well-ordered dimers
exhibit a first-order magnetic transition with the onset exceeding 550~K,
higher than that reported previously. We discuss possible dimer configurations
leading to this magneto-lattice coupling.


title:
High solar cycle spectral variations inconsistent with stratospheric
  ozone observations

abstract:
  Some of the natural variability in climate is understood to come from changes
in the Sun. A key route whereby the Sun may influence surface climate is
initiated in the tropical stratosphere by the absorption of solar ultraviolet
(UV) radiation by ozone, leading to a modification of the temperature and wind
structures and consequently to the surface through changes in wave propagation
and circulation. While changes in total, spectrally-integrated, solar
irradiance lead to small variations in global mean surface temperature, the
`top-down' UV effect preferentially influences on regional scales at
mid-to-high latitudes with, in particular, a solar signal noted in the North
Atlantic Oscillation (NAO). The amplitude of the UV variability is fundamental
in determining the magnitude of the climate response but understanding of the
UV variations has been challenged recently by measurements from the SOlar
Radiation and Climate Experiment (SORCE) satellite, which show UV solar cycle
changes up to 10 times larger than previously thought. Indeed, climate models
using these larger UV variations show a much greater response, similar to NAO
observations. Here we present estimates of the ozone solar cycle response using
a chemistry-climate model (CCM) in which the effects of transport are
constrained by observations. Thus the photolytic response to different spectral
solar irradiance (SSI) datasets can be isolated. Comparison of the results with
the solar signal in ozone extracted from observational datasets yields
significantly discriminable responses. According to our evaluation the SORCE UV
dataset is not consistent with the observed ozone response whereas the smaller
variations suggested by earlier satellite datasets, and by UV data from
empirical solar models, are in closer agreement with the measured stratospheric
variations. Determining the most appropriate SSI variability to apply in
models...


title:
Investigation of the electron-phonon interaction in $N{{b}_{3}}Sn$ with
  the aid of microcontacts

abstract:
  The method of microcontact spectroscopy in the superconducting state was used
to investigate weak nonlinearities of the current-voltage characteristics of
point contacts made of $N{{b}_{3}}Sn$ single crystals. The nature of the
spectrum of the electron-phonon interaction was found to vary considerably from
contact to contact, indicating considerable deviations of the composition of
the surface of $N{{b}_{3}}Sn$ from stoichiometry. A correlation was established
between the nature of the spectrum and the magnitude of the gap singularities
of the current-voltage characteristics. In the case of "dirty" high-resistance
contacts with strong gap singularities the microcontact spectra were reasonably
reproducible, which made it possible to relate them sufficiently closely to the
microcontact function of the electron-phonon interaction in the bulk material.
It was found that microcontact spectroscopy of this interaction was possible in
the superconducting state not only in dirty $S-c-S$ contacts, but also in dirty
$S-c-N$ contacts.


title:
Restricted $q$-Isometry Properties Adapted to Frames for Nonconvex
  $l_q$-Analysis

abstract:
  This paper discusses reconstruction of signals from few measurements in the
situation that signals are sparse or approximately sparse in terms of a general
frame via the $l_q$-analysis optimization with $0<q\leq 1$. We first introduce
a notion of restricted $q$-isometry property ($q$-RIP) adapted to a dictionary,
which is a natural extension of the standard $q$-RIP, and establish a
generalized $q$-RIP condition for approximate reconstruction of signals via the
$l_q$-analysis optimization. We then determine how many random, Gaussian
measurements are needed for the condition to hold with high probability. The
resulting sufficient condition is met by fewer measurements for smaller $q$
than when $q=1$.
  The introduced generalized $q$-RIP is also useful in compressed data
separation. In compressed data separation, one considers the problem of
reconstruction of signals' distinct subcomponents, which are (approximately)
sparse in morphologically different dictionaries, from few measurements. With
the notion of generalized $q$-RIP, we show that under an usual assumption that
the dictionaries satisfy a mutual coherence condition, the $l_q$ split analysis
with $0<q\leq1 $ can approximately reconstruct the distinct components from
fewer random Gaussian measurements with small $q$ than when $q=1$


title: Numerical study of the Kerr solution in rotating coordinates

abstract:
  The Kerr solution in coordinates corotating with the horizon is studied as a
testbed for a spacetime with a helical Killing vector in the Ernst picture. The
solution is numerically constructed by solving the Ernst equation with a
spectral method and a Newton iteration. We discuss convergence of the iteration
for several initial iterates and different values of the Kerr parameters.


title:
graphVizdb: A Scalable Platform for Interactive Large Graph
  Visualization

abstract:
  We present a novel platform for the interactive visualization of very large
graphs. The platform enables the user to interact with the visualized graph in
a way that is very similar to the exploration of maps at multiple levels. Our
approach involves an offline preprocessing phase that builds the layout of the
graph by assigning coordinates to its nodes with respect to a Euclidean plane.
The respective points are indexed with a spatial data structure, i.e., an
R-tree, and stored in a database. Multiple abstraction layers of the graph
based on various criteria are also created offline, and they are indexed
similarly so that the user can explore the dataset at different levels of
granularity, depending on her particular needs. Then, our system translates
user operations into simple and very efficient spatial operations (i.e., window
queries) in the backend. This technique allows for a fine-grained access to
very large graphs with extremely low latency and memory requirements and
without compromising the functionality of the tool. Our web-based prototype
supports three main operations: (1) interactive navigation, (2) multi-level
exploration, and (3) keyword search on the graph metadata.


title: Band structure diagram paths based on crystallography

abstract:
  Systematic and automatic calculations of the electronic band structure are a
crucial component of computationally-driven high-throughput materials
screening. An algorithm, for any crystal, to derive a unique description of the
crystal structure together with a recommended band path is indispensable for
this task. The electronic band structure is typically sampled along a path
within the first Brillouin zone including the surface in reciprocal space. Some
points in reciprocal space have higher site symmetries and/or have higher
constraints than other points regarding the electronic band structure and
therefore are likely to be more important than other points. This work
categorizes points in reciprocal space according to their symmetry and provides
recommended band paths that cover all special wavevector (k-vector) points and
lines necessarily and sufficiently. Points in reciprocal space are labeled such
that there is no conflict with the crystallographic convention. The k-vector
coefficients of labeled points, which are located at Brillouin zone face and
edge centers as well as vertices, are derived based on a primitive cell
compatible with the crystallographic convention, including those with axial
ratio-dependent coordinates. Furthermore, we provide an open-source
implementation of the algorithms within our SeeK-path python code, to allow
researchers to obtain k-vector coefficients and recommended band paths in an
automated fashion. Finally, we created a free online service to compute and
visualise Brillouin Zone, labeled k-points and suggested band paths for any
crystal structure, that we made available at
http://www.materialscloud.org/tools/seekpath/ .


title: The motive of the Fano surface of lines

abstract:
  The purpose of this note is to prove that the Chow motive of the Fano surface
of lines on the smooth cubic threefold is finite-dimensional in the sense of
Kimura. This gives an example of a smooth projective variety that is not
dominated by a product of curves but whose Chow motive is of Abelian type.


title: Control of epidemics via social partnership adjustment

abstract:
  Epidemic control is of great importance for human society. Adjusting
interacting partners is an effective individualized control strategy.
Intuitively, it is done either by shortening the interaction time between
susceptible and infected individuals or by increasing the opportunities for
contact between susceptible individuals. Here, we provide a comparative study
on these two control strategies by establishing an epidemic model with
non-uniform stochastic interactions. It seems that the two strategies should be
similar, since shortening the interaction time between susceptible and infected
individuals somehow increases the chances for contact between susceptible
individuals. However, analytical results indicate that the effectiveness of the
former strategy sensitively depends on the infectious intensity and the
combinations of different interaction rates, whereas the latter one is quite
robust and efficient. Simulations are shown in comparison with our analytical
predictions. Our work may shed light on the strategic choice of disease
control.


title:
Interaction of atom with non-paraxial Laguerre-Gaussian beam:Forming
  superposition of vortex states in Bose-Einstein condensates

abstract:
  The exchange of orbital angular momentum (OAM) between paraxial optical
vortex and a Bose-Einstein condensate (BEC) of atomic gases is well known. In
this paper, we develop a theory for the microscopic interaction between matter
and an optical vortex beyond paraxial approximation. We show how superposition
of vortex states of BEC can be created with a focused optical vortex. Since,
the polarization or spin angular momentum (SAM) of the optical field is coupled
with OAM of the field, in this case, these angular momenta can be transferred
to the internal electronic and external center-of-mass (c.m.) motion of atoms
provided both the motions are coupled. We propose a scheme for producing the
superposition of matter-wave vortices using Gaussian and a focused
Laguerre-Gaussian (LG) beam. We study how two-photon Rabi frequencies of
stimulated Raman transitions vary with focusing angles for different
combinations of OAM and SAM of optical states. We demonstrate the formation of
vortex-antivortex structure and discuss interference of three vortex states in
a BEC.


title: On the Role of Side Information In Strategic Communication

abstract:
  This paper analyzes the fundamental limits of strate- gic communication in
network settings. Strategic communication differs from the conventional
communication paradigms in in- formation theory since it involves different
objectives for the encoder and the decoder, which are aware of this mismatch
and act accordingly. This leads to a Stackelberg game where both agents commit
to their mappings ex-ante. Building on our prior work on the point-to-point
setting, this paper studies the compression and communication problems with the
receiver and/or transmitter side information setting. The equilibrium
strategies and associated costs are characterized for the Gaussian variables
with quadratic cost functions. Several questions on the benefit of side
information in source and joint source-channel coding in such strategic
settings are analyzed. Our analysis has uncovered an interesting result on
optimality of uncoded mappings in strategic source-channel coding in networks.


title: A Reduction System for Optimal 1-Planar Graphs

abstract:
  There is a graph reduction system so that every optimal 1-planar graph can be
reduced to an irreducible extended wheel graph, provided the reductions are
applied such that the given graph class is preserved. A graph is optimal
1-planar if it can be drawn in the plane with at most one crossing per edge and
is optimal if it has the maximum of 4n-8 edges.
  We show that the reduction system is context-sensitive so that the
preservation of the graph class can be granted by local conditions which can be
tested in constant time. Every optimal 1-planar graph G can be reduced to every
extended wheel graph whose size is in a range from the (second) smallest one to
some upper bound that depends on G. There is a reduction to the smallest
extended wheel graph if G is not 5-connected, but not conversely. The reduction
system has side effects and is non-deterministic and non-confluent.
Nevertheless, reductions can be computed in linear time.


title: Universality in boundary domain growth by sudden bridging

abstract:
  We report on universality in boundary domain growth in cluster aggregation in
the limit of maximum concentration. Maximal concentration means that the
diffusivity of the clusters is effectively zero and, instead, clusters merge
successively in a percolation process, which leads to a sudden growth of the
boundary domains. For two-dimensional square lattices of linear dimension L,
independent of the models studied here, we find that the maximum of the
boundary interface width, the susceptibility $\chi$, exhibits the scaling $\chi
\sim L^{\gamma}$ with the universal exponent $\gamma = 1$. The rapid growth of
the boundary domain at the percolation threshold, which is guaranteed to occur
for almost {\em any} cluster percolation process, underlies the universal
scaling of $\chi$.


title:
Effects of finite size and symmetry energy on the phase transition of
  stellar matter at subnuclear densities

abstract:
  We study the liquid-gas phase transition of stellar matter with the inclusion
of the finite-size effect from surface and Coulomb energies. The equilibrium
conditions for two coexisting phases are determined by minimizing the total
free energy including the surface and Coulomb contributions, which are
different from the Gibbs conditions used in the bulk calculations. The
finite-size effect can significantly reduce the region of the liquid-gas mixed
phase. The influence of the symmetry energy on the liquid-gas phase transition
is investigated with the inclusion of finite-size effects. It is found that the
slope of the symmetry energy plays an important role in determining the
boundary and properties of the mixed phase.


title: Semidefinite Programs for Exact Recovery of a Hidden Community

abstract:
  We study a semidefinite programming (SDP) relaxation of the maximum
likelihood estimation for exactly recovering a hidden community of cardinality
$K$ from an $n \times n$ symmetric data matrix $A$, where for distinct indices
$i,j$, $A_{ij} \sim P$ if $i, j$ are both in the community and $A_{ij} \sim Q$
otherwise, for two known probability distributions $P$ and $Q$. We identify a
sufficient condition and a necessary condition for the success of SDP for the
general model. For both the Bernoulli case ($P={{\rm Bern}}(p)$ and $Q={{\rm
Bern}}(q)$ with $p>q$) and the Gaussian case ($P=\mathcal{N}(\mu,1)$ and
$Q=\mathcal{N}(0,1)$ with $\mu>0$), which correspond to the problem of planted
dense subgraph recovery and submatrix localization respectively, the general
results lead to the following findings: (1) If $K=\omega( n /\log n)$, SDP
attains the information-theoretic recovery limits with sharp constants; (2) If
$K=\Theta(n/\log n)$, SDP is order-wise optimal, but strictly suboptimal by a
constant factor; (3) If $K=o(n/\log n)$ and $K \to \infty$, SDP is order-wise
suboptimal. The same critical scaling for $K$ is found to hold, up to constant
factors, for the performance of SDP on the stochastic block model of $n$
vertices partitioned into multiple communities of equal size $K$. A key
ingredient in the proof of the necessary condition is a construction of a
primal feasible solution based on random perturbation of the true cluster
matrix.

categories: stat.ML cs.IT cs.SI math.IT math.ST stat.TH


title:
On the Size and the Approximability of Minimum Temporally Connected
  Subgraphs

abstract:
  We consider temporal graphs with discrete time labels and investigate the
size and the approximability of minimum temporally connected spanning
subgraphs. We present a family of minimally connected temporal graphs with $n$
vertices and $\Omega(n^2)$ edges, thus resolving an open question of (Kempe,
Kleinberg, Kumar, JCSS 64, 2002) about the existence of sparse temporal
connectivity certificates. Next, we consider the problem of computing a minimum
weight subset of temporal edges that preserve connectivity of a given temporal
graph either from a given vertex r (r-MTC problem) or among all vertex pairs
(MTC problem). We show that the approximability of r-MTC is closely related to
the approximability of Directed Steiner Tree and that r-MTC can be solved in
polynomial time if the underlying graph has bounded treewidth. We also show
that the best approximation ratio for MTC is at least $O(2^{\log^{1-\epsilon}
n})$ and at most $O(\min\{n^{1+\epsilon}, (\Delta M)^{2/3+\epsilon}\})$, for
any constant $\epsilon > 0$, where $M$ is the number of temporal edges and
$\Delta$ is the maximum degree of the underlying graph. Furthermore, we prove
that the unweighted version of MTC is APX-hard and that MTC is efficiently
solvable in trees and $2$-approximable in cycles.


title:
A pulsation analysis of K2 observations of the subdwarf B star
  PG1142-037 during Campaign 1: A subsynchronously rotating ellipsoidal
  variable

abstract:
  We report a new subdwarf B (sdB) pulsator, PG1142-037, discovered during the
first full-length campaign of K2, the two-gyro mission of the Kepler space
telescope. Fourteen periodicities have been detected between 0.9 and 2.5 hours
with amplitudes below 0.35 ppt. We have been able to associate all of the
pulsations with low-degree, ell<=2 modes. Follow-up spectroscopy of PG1142 has
revealed it to be in a binary with a period of 0.54 days. Phase-folding the K2
photometry reveals a two-component variation including both Doppler boosting
and ellipsoidal deformation. Perhaps the most surprising and interesting result
is the detection of an ellipsoidal, tidally distorted variable with no
indication of rotationally-induced pulsation multiplets. This indicates that
the rotation period is longer than 45 days, even though the binary period is
near 13 hours.


title: Determination of the symmetry classes of orientational ordering tensors

abstract:
  The orientational order of nematic liquid crystals is traditionally studied
by means of the second-rank ordering tensor $\mathbb{S}$. When this is
calculated through experiments or simulations, the symmetry group of the phase
is not known \emph{a-priori}, but needs to be deduced from the numerical
realisation of $\mathbb{S}$, which is affected by numerical errors. There is no
generally accepted procedure to perform this analysis. Here, we provide a new
algorithm suited to identifying the symmetry group of the phase. As a by
product, we prove that there are only five phase-symmetry classes of the
second-rank ordering tensor and give a canonical representation of $\mathbb{S}$
for each class. The nearest tensor of the assigned symmetry is determined by
group-projection. In order to test our procedure, we generate uniaxial and
biaxial phases in a system of interacting particles, endowed with $D_{\infty
h}$ or $D_{2h}$, which mimic the outcome of Monte-Carlo simulations. The actual
symmetry of the phases is correctly identified, along with the optimal choice
of laboratory frame.


title: A "high-hard" outburst of the black hole X-ray binary GS 1354-64

abstract:
  We study in detail the evolution of the 2015 outburst of GS 1354-64 (BW Cir)
at optical, UV and X-ray wavelengths using Faulkes Telescope South/LCOGT,
SMARTS and Swift. The outburst was found to stay in the hard X-ray state,
albeit being anomalously luminous with a peak luminosity of L$_{X} >$ 0.15
L$_{Edd}$, which could be the most luminous hard state observed in a black hole
X-ray binary. We found that the optical/UV emission is tightly correlated with
the X-ray emission, consistent with accretion disc irradiation and/or a jet
producing the optical emission. The X-ray spectra can be fitted well with a
Comptonisation model, and show softening towards the end of the outburst. In
addition, we detect a QPO in the X-ray lightcurves with increasing centroid
frequency during the peak and decay periods of the outburst. The long-term
optical lightcurves during quiescence show a statistically significant, slow
rise of the source brightness over the 7 years prior to the 2015 outburst. This
behaviour as well as the outburst evolution at all wavelengths studied can be
explained by the disc instability model with irradiation and disc
evaporation/condensation.


title:
Proton entry into the near-lunar plasma wake for magnetic field aligned
  flow

abstract:
  We report the first observation of protons in the near (100--200 km from
surface) and deeper (near anti-subsolar point) lunar plasma wake when the
interplanetary magnetic field (IMF) and solar wind velocity ($v_{sw}$) are
parallel (aligned flow, angle between IMF and ($v_{sw} \le 10^\circ$). More
than 98% of the observations during aligned flow condition showed the presence
of protons in the wake. These observations are obtained by the SWIM sensor of
the SARA experiment on Chandrayaan-1. The observation cannot be explained by
the conventional fluid models for aligned flow. Back-tracing of the observed
protons suggests that their source is the solar wind. The larger gyro-radii of
the wake protons compared to that of solar wind suggest that they were part of
the tail of the solar wind velocity distribution function. Such protons could
enter the wake due to their large gyro-radii even when the flow is aligned to
IMF. However, the wake boundary electric field may also play a role in the
entry of the protons in to the wake.


title: A lattice model of reduced jamming by barrier

abstract:
  We study an asymmetric simple exclusion process in a strip in the presence of
a solid impenetrable barrier. We focus on the effect of the barrier on the
residence time of the particles, namely, the typical time needed by the
particles to cross the whole strip. We explore the conditions for reduced
jamming when varying the environment (different drifts, reservoir densities,
horizontal diffusion walks, etc.). Particularly, we discover an interesting
non--monotonic behavior of the residence time as a function of the barrier
length. Besides recovering by means of both the lattice dynamics and mean-field
model well-known aspects like faster-is-slower effect and the intermittence of
the flow, we propose also a birth-and-death process and a reduced
one-dimensional model with variable barrier permeability to capture
qualitatively the behavior of the residence time with respect to the
parameters. We report our first steps towards the understanding to which extent
the presence of obstacles can fluidize pedestrian and biological transport in
crowded heterogeneous environments.

categories: cond-mat.stat-mech math-ph math.MP nlin.CG


title:
Order-Reduction Abstractions for Safety Verification of High-Dimensional
  Linear Systems

abstract:
  Order-reduction is a standard automated approximation technique for
computer-aided design, analysis, and simulation of many classes of systems,
from circuits to buildings. For a given system, these methods produce a
reduced-order system where the dimension of the state-space is smaller, while
attempting to preserve behaviors similar to those of the full-order original
system. To be used as a sound abstraction for formal verification, a measure of
the similarity of behavior must be formalized and computed, which we develop in
a computational way for a class of linear systems and periodically-switched
systems as the main contributions of this paper. We have implemented the
order-reduction as a sound abstraction process through a source-to-source model
transformation in the HyST tool and use SpaceEx to compute sets of reachable
states to verify properties of the full-order system through analysis of the
reduced-order system. Our experimental results suggest systems with on the
order of a thousand state variables can be reduced to systems with tens of
state variables such that the order-reduction overapproximation error is small
enough to prove or disprove safety properties of interest using current
reachability analysis tools. Our results illustrate this approach is effective
to alleviate the state-space explosion problem for verification of
high-dimensional linear systems.


title:
Pad\'e Approximant and Minimax Rational Approximation in Standard
  Cosmology

abstract:
  The luminosity distance in the standard cosmology as given by $\Lambda$CDM
and consequently the distance modulus for supernovae can be defined by the
Pad\'e approximant. A comparison with a known analytical solution shows that
the Pad\'e approximant for the luminosity distance has an error of $4\%$ at
redshift $= 10$. A similar procedure for the Taylor expansion of the luminosity
distance gives an error of $4\%$ at redshift $=0.7 $; this means that for the
luminosity distance, the Pad\'e approximation is superior to the Taylor series.
The availability of an analytical expression for the distance modulus allows
applying the Levenberg--Marquardt method to derive the fundamental parameters
from the available compilations for supernovae. A new luminosity function for
galaxies derived from the truncated gamma probability density function models
the observed luminosity function for galaxies when the observed range in
absolute magnitude is modeled by the Pad\'e approximant. A comparison of
$\Lambda$CDM with other cosmologies is done adopting a statistical point of
view.


title: Evaluation of the CHY Gauge Amplitude

abstract:
  The Cachazo-He-Yuan (CHY) formula for $n$-gluon scattering is known to give
the same amplitude as the one obtained from Feynman diagrams, though the former
contains neither vertices nor propagators explicitly. The equivalence was shown
by indirect means, not by a direct evaluation of the $(n\! - \!3)$-dimensional
integral in the CHY formula. The purpose of this paper is to discuss how such a
direct evaluation can be carried out. There are two basic difficulties in the
calculation: how to handle the large number of terms in the reduced Pfaffian,
and how to carry out the integrations in the presence of a $\sigma$-dependence
much more complicated than the Parke-Taylor form found in a CHY double-color
scalar amplitude. We have solved both of these problems, and have formulated a
method that can be applied to any $n$. Many examples are provided to illustrate
these calculations.


title:
A Probabilistic Dependent Type System based on Non-Deterministic Beta
  Reduction

abstract:
  We introduce Probabilistic Dependent Type Systems (PDTS) via a functional
language based on a subsystem of intuitionistic type theory including dependent
sums and products, which is expanded to include stochastic functions. We
provide a sampling-based semantics for the language based on non-deterministic
beta reduction. Further, we derive a probabilistic logic from the PDTS
introduced as a direct result of the Curry-Howard isomorphism. The
probabilistic logic derived is shown to provide a universal representation for
finite discrete distributions.


title: Localizations of inductively factored arrangements

abstract:
  We show that the class of inductively factored arrangements is closed under
taking localizations. We illustrate the usefulness of this with an application.


title: Four-point function in the IOP matrix model

abstract:
  The IOP model is a quantum mechanical system of a large-$N$ matrix oscillator
and a fundamental oscillator, coupled through a quartic interaction. It was
introduced previously as a toy model of the gauge dual of an AdS black hole,
and captures a key property that at infinite $N$ the two-point function decays
to zero on long time scales. Motivated by recent work on quantum chaos, we sum
all planar Feynman diagrams contributing to the four-point function. We find
that the IOP model does not satisfy the more refined criteria of exponential
growth of the out-of-time-order four-point function.


title: Challenges in Analogical Reasoning

abstract:
  Learning physics requires understanding the applicability of fundamental
principles in a variety of contexts that share deep features. One way to help
students learn physics is via analogical reasoning. Students can be taught to
make an analogy between situations that are more familiar or easier to
understand and another situation where the same physics principle is involved
but that is more difficult to handle. Here, we examine introductory physics
students' ability to use analogies in solving problems involving Newton's
second law. Students enrolled in an algebra-based introductory physics course
were given a solved problem involving tension in a rope and were then asked to
solve another problem for which the physics is very similar but involved a
frictional force. They were asked to point out the similarities between the two
problems and then use the analogy to solve the friction problem.


title:
Characteristics of proton velocity distribution functions in the
  near-lunar wake from Chandrayaan-1/SWIM observations

abstract:
  Due to the high absorption of solar wind plasma on the lunar dayside, a large
scale wake structure is formed downstream of the Moon. However, recent in-situ
observations have revealed the presence of protons in the near-lunar wake (100
km to 200 km from the surface). The solar wind, either directly or after
interaction with the lunar surface (including magnetic anomalies), is the
source of these protons in the near-wake region. Using the entire data from the
SWIM sensor of the SARA experiment onboard Chandrayaan-1, we analysed the
velocity distribution of the protons observed in the near-lunar wake. The
average velocity distribution functions, computed in the solar wind rest frame,
were further separated based on the angle between the upstream solar wind
velocity and the IMF. Several proton populations were identified from the
velocity distribution and their possible entry mechanism were inferred based on
the characteristics of the velocity distribution. These entry mechanisms
include (i) diffusion of solar wind protons into the wake along IMF, (ii) the
solar wind protons with finite gyro-radii that are aided by the wake boundary
electric field, (iii) solar wind protons with gyro-radii larger than lunar
radii from the tail of the solar wind velocity distribution, and (iv)
scattering of solar wind protons from the dayside lunar surface or from
magnetic anomalies. In order to gain more insight into the entry mechanisms
associated with different populations, backtracing is carried out for each of
these populations. For most of the populations, the source of the protons
obtained from backtracing is found to be in agreement with that inferred from
the velocity distribution. There are few populations that could not be
explained by the known mechanisms and remain unknown.


title: Covalent bonds against magnetism in transition metal compounds

abstract:
  Magnetism in transition metal compounds is usually considered starting from a
description of isolated ions, as exact as possible, and treating their
(exchange) interaction at a later stage. We show that this standard approach
may break down in many cases, especially in $4d$ and $5d$ compounds. We argue
that there is an important intersite effect -- an orbital-selective formation
of covalent metal-metal bonds, which leads to an "exclusion" of corresponding
electrons from the magnetic subsystem, and thus strongly affects magnetic
properties of the system. This effect is especially prominent for noninteger
electron number, when it results in suppression of the famous double exchange,
the main mechanism of ferromagnetism in transition metal compounds. We study
this novel mechanism analytically and numerically and show that it explains
magnetic properties of not only several $4d-5d$ materials, including
Nb$_2$O$_2$F$_3$ and Ba$_5$AlIr$_2$O$_{11}$, but can also be operative in $3d$
transition metal oxides, e.g. in CrO$_2$ under pressure. We also discuss the
role of spin-orbit coupling on the competition between covalency and magnetism.
Our results demonstrate that strong intersite coupling may invalidate the
standard single-site starting point for considering magnetism, and can lead to
a qualitatively new behaviour.


title:
A loopless and branchless $O(1)$ algorithm to generate the next Dyck
  word

abstract:
  Let integer be any C/C++ unsigned integer type up to 64-bits long. Given a
Dyck word the following code returns the next Dyck word of the same size,
provided it exists.
  integer next_dyck_word(integer w) {
  integer const a = w & -w;
  integer const b = w + a;
  integer c = w ^ b;
  c = (c / a >> 2) + 1;
  c = ((c * c - 1) & 0xaaaaaaaaaaaaaaaa) | b;
  return c;
  }


title: Correspondence between 2 Calabi-Yau Categories and Quivers

abstract:
  This note gives a one-to-one correspondence between the equivalence classes
of a certain type of 2-dimensional Calabi-Yau categories, and certain type of
quivers, This is an analogue of the result in Stability structures, motivic
Donaldson-Thomas invariants and cluster transformations, arXiv: 0811.2435, by
M. Kontsevich, Y. Soibelman.


title:
Mathematical modeling of interdigitated electrode arrays in finite
  electrochemical cells

abstract:
  Accurate theoretical results for interdigitated array of electrodes (IDAE) in
semi-infinite cells can be found in the literature. However, these results are
not always applicable when using finite cells. In this study, theoretical
expressions for IDAE in a finite geometry cell are presented. At known current
density, transient and steady state concentration profiles were obtained as
well as the response time to a current step. Concerning the diffusion limited
current, a lower bound was derived from the concentration profile and an upper
bound was obtained from the limiting current of the semi-infinite case. The
lower bound, which is valid when Kirchhoff's current law applies to the unit
cell, can be useful to ensure a minimum current level during the design of the
electrochemical cell. Finally, a criterion was developed defining when the
behaviors of finite and semi-infinite cells are comparable. This allows to
obtain higher current levels in finite cells, approaching that of the
semi-infinite case. Examples with simulations were performed in order to
illustrate and validate the theoretical results.


title:
Generalized Statistical Tests for mRNA and Protein Subcellular Spatial
  Patterning against Complete Spatial Randomness

abstract:
  We derive generalized estimators for a number of spatial statistics that have
been used in the analysis of spatially resolved omics data, such as Ripley's K,
H and L functions, clustering index, and degree of clustering, which allow
these statistics to be calculated on data modelled by arbitrary random measures
(RMs). Our estimators generalize those typically used to calculate these
statistics on point process data, allowing them to be calculated on RMs which
assign continuous values to spatial regions, for instance to model protein
intensity. The clustering index (H*) compares Ripley's H function calculated
empirically to its distribution under complete spatial randomness (CSR),
leading us to consider CSR null hypotheses for RMs which are not
point-processes when generalizing this statistic. We thus consider restricted
classes of completely random measures which can be simulated directly (Gamma
processes and Marked Poisson Processes), as well as the general class of all
CSR RMs, for which we derive an exact permutation-based H* estimator. We
establish several properties of the estimators, including bounds on the
accuracy of our general Ripley K estimator, its relationship to a previous
estimator for the cross-correlation measure, and the relationship of our
generalized H* estimator to previous statistics. To test the ability of our
approach to identify spatial patterning, we use Fluorescent In Situ
Hybridization (FISH) and Immunofluorescence (IF) data to probe for mRNA and
protein subcellular localization patterns respectively in polarizing mouse
fibroblasts on micropattened cells. We observe correlated patterns of
clustering over time for corresponding mRNAs and proteins, suggesting a
deterministic effect of mRNA localization on protein localization for several
pairs tested, including one case in which spatial patterning at the mRNA level
has not been previously demonstrated.


title:
More on the metric projection onto a closed convex set in a Hilbert
  space

abstract:
  In this note, we highlight some properties of the metric projection onto a
closed convex in a Hilbert space. In particular, we use some recent results on
fixed points of nonexpansive potential operators.


title:
Burstiness Scale: a highly parsimonious model for characterizing random
  series of events

abstract:
  The problem to accurately and parsimoniously characterize random series of
events (RSEs) present in the Web, such as e-mail conversations or Twitter
hashtags, is not trivial. Reports found in the literature reveal two apparent
conflicting visions of how RSEs should be modeled. From one side, the
Poissonian processes, of which consecutive events follow each other at a
relatively regular time and should not be correlated. On the other side, the
self-exciting processes, which are able to generate bursts of correlated events
and periods of inactivities. The existence of many and sometimes conflicting
approaches to model RSEs is a consequence of the unpredictability of the
aggregated dynamics of our individual and routine activities, which sometimes
show simple patterns, but sometimes results in irregular rising and falling
trends. In this paper we propose a highly parsimonious way to characterize
general RSEs, namely the Burstiness Scale (BuSca) model. BuSca views each RSE
as a mix of two independent process: a Poissonian and a self-exciting one. Here
we describe a fast method to extract the two parameters of BuSca that,
together, gives the burstyness scale, which represents how much of the RSE is
due to bursty and viral effects. We validated our method in eight diverse and
large datasets containing real random series of events seen in Twitter, Yelp,
e-mail conversations, Digg, and online forums. Results showed that, even using
only two parameters, BuSca is able to accurately describe RSEs seen in these
diverse systems, what can leverage many applications.


title: Scheme for accelerating quantum tunneling dynamics

abstract:
  We propose a scheme of the exact fast-forwarding of standard quantum dynamics
for a charged particle. The present idea allows the acceleration of both the
amplitude and phase of the wave function throughout the fast-forward time range
and is distinct from that of Masuda-Nakamura (e.g., Proc. R. Soc. A {\bf 466},
1135 (2010)) which enabled acceleration of only the amplitude of the wave
function on the way. We shall apply the proposed method to the quantum
tunneling phenomena and obtain the electro-magnetic field to ensure the rapid
penetration of wave functions through a tunneling barrier. Typical examples
described here are: 1) an exponential wave packet passing through the
delta-function barrier; 2) the opened Moshinsky shutter with a delta-function
barrier just behind the shutter. We elucidate the tunneling current in the
vicinity of the barrier and find the remarkable enhancement of the tunneling
rate (: tunneling power) due to the fast-forwarding. In the case of a very high
barrier, in particular, we present the asymptotic analysis and exhibit a
suitable driving force to recover a recognizable tunneling current. The
analysis is also carried out on the exact acceleration of macroscopic quantum
tunneling with use of the nonlinear Schr\"odinger equation which accommodates a
tunneling barrier.


title: Polish globalization of Polish group partial actions

abstract:
  Let $X$ be a separable metrizable space. We establish a criteria for the
existence of a metrizable globalization for a given continuous partial action
of a separable metrizable group $G$ on $X.$ If $G$ and $X$ are Polish spaces,
we show that the globalization is also a Polish space. We also show the
existence of an universal globalization for partial actions of Polish groups.


title:
Energy Conservation and Power Bonds in Co-Simulations: Non-Iterative
  Adaptive Step Size Control and Error Estimation

abstract:
  Here, we study the flow of energy between coupled simulators in a
co-simulation environment using the concept of power bonds. We introduce energy
residuals which are a direct expression of the coupling errors and hence the
accuracy of co-simulation results. We propose a novel Energy-Conservation-based
Co-Simulation method (ECCO) for adaptive macro step size control to improve
accuracy and efficiency. In contrast to most other co-simulation algorithms,
this method is non-iterative and only requires knowledge of the current
coupling data. Consequently, it allows for significant speed ups and the
protection of sensitive information contained within simulator models. A
quarter car model with linear and nonlinear damping serves as a co-simulation
benchmark and verifies the capabilities of the energy residual concept:
Reductions in the errors of up to 93% are achieved at no additional
computational cost.


title: Nonstandard homology theory for uniform spaces

abstract:
  We introduce a new homology theory of uniform spaces, provisionally called
$\mu$-homology theory. Our homology theory is based on hyperfinite chains of
microsimplices. This idea is due to McCord. We prove that $\mu$-homology theory
satisfies the Eilenberg-Steenrod axioms. The characterization of
chain-connectedness in terms of $\mu$-homology is provided. We also introduce
the notion of S-homotopy, which is weaker than uniform homotopy. We prove that
$\mu$-homology theory satisfies the S-homotopy axiom, and that every uniform
space can be S-deformation retracted to a dense subset. It follows that for
every uniform space $X$ and any dense subset $A$ of $X$, $X$ and $A$ have the
same $\mu$-homology. We briefly discuss the difference and similarity between
$\mu$-homology and McCord homology.


title: On a Lattice-Independent Formulation of Quantum Holonomy Theory

abstract:
  Quantum holonomy theory is a candidate for a non-perturbative theory of
quantum gravity coupled to fermions. The theory is based on the QHD(M) algebra,
which essentially encodes how matter degrees of freedom are moved on a
three-dimensional manifold. In this paper we commence the development of a
lattice-independent formulation. We first introduce a flow-dependent version of
the QHD(M) algebra and formulate necessary conditions for a state to exist
hereon. We then use the GNS construction to build a kinematical Hilbert space.
Finally we find that operators, that correspond to the Dirac and gravitational
Hamiltonians in a semi-classical limit, are background independent.


title: Perturbative Unitarity Bounds in Composite 2-Higgs Doublet Models

abstract:
  We study bounds from perturbative unitarity in a Composite 2-Higgs Doublet
Model (C2HDM) based on the spontaneous breakdown of a global symmetry $SO(6)\to
SO(4)\times SO(2)$ at the compositeness scale $f$. The eight pseudo
Nambu-Goldstone Bosons (pNGBs) emerging from such a dynamics are identified as
two isospin doublet Higgs fields. We calculate the $S$-wave amplitude for all
possible 2-to-2-body elastic (pseudo)scalar boson scatterings at energy scales
$\sqrt{s}$ reachable at the Large Hadron Collider (LHC) and beyond it,
including the longitudinal components of weak gauge boson states as the
corresponding pNGB states. In our calculation, the Higgs potential is assumed
to have the same form as that in the Elementary 2-Higgs Doublet Model (E2HDM)
with a discrete $Z_2$ symmetry, which is expected to be generated at the
one-loop level via the Coleman-Weinberg (CW) mechanism. We find that the
$S$-wave amplitude matrix can be block-diagonalized with maximally $2\times 2$
submatrices in a way similar to the E2HDM case as long as we only keep the
contributions from ${\cal O }(\xi s)$ and ${\cal O }(\xi^0 s^0)$ in the
amplitudes, where $\xi=v_{\text{SM}}^2/f^2$ and $v_{\text{SM}}^{}\simeq 246$
GeV, which is an appropriate approximation for our analysis. By requiring the
C2HDM to satisfy perturbative unitarity at energies reachable by the LHC, we
derive bounds on its parameters such as $\xi$ and the masses of extra Higgs
bosons present in the scenario alongside the Standard Model (SM)-like Higgs
state discovered in 2012.


title:
Iteration scheme for initial value problem for PDEs: Existence,
  convergence and comparison

abstract:
  Results about existence and uniqueness of solutions of initial value problem
for certain types of partial differential equations are recalled as well as
iterative scheme and an error estimate for approximate solutions obtained using
this scheme. Several numerical examples are presented to demonstrate how the
proposed iterative scheme can be applied, with emphasis given to verifying
assumptions of using the scheme. Comparison to other recently presented results
is done in this respect.


title: Context-guided diffusion for label propagation on graphs

abstract:
  Existing approaches for diffusion on graphs, e.g., for label propagation, are
mainly focused on isotropic diffusion, which is induced by the commonly-used
graph Laplacian regularizer. Inspired by the success of diffusivity tensors for
anisotropic diffusion in image processing, we presents anisotropic diffusion on
graphs and the corresponding label propagation algorithm. We develop positive
definite diffusivity operators on the vector bundles of Riemannian manifolds,
and discretize them to diffusivity operators on graphs. This enables us to
easily define new robust diffusivity operators which significantly improve
semi-supervised learning performance over existing diffusion algorithms.


title: Lower bounds for codimension-1 measure in metric manifolds

abstract:
  We establish Euclidean-type lower bounds for the codimension-1 Hausdorff
measure of sets that separate points in doubling and linearly locally
contractible metric manifolds. This gives a quantitative topological
isoperimetric inequality in the setting of metric manifolds, in the sense that
lower bounds for the codimension-1 measure of a set depend not on some notion
of filling or volume but rather on in-radii of complementary components. As a
consequence, we show that balls in a closed, connected, doubling, and linearly
locally contractible metric $n$-manifold $(M,d)$ with radius $0<r \leq
\text{diam}(M)$ have $n$-dimensional Hausdorff measure at least $c \cdot r^n$,
where $c>0$ depends only on $n$ and on the doubling and linear local
contractibility constants.


title: What Can Learn from PER: Physics Education Research?

abstract:
  I believe that most teachers develop a belief in a set of pedagogical
practices. As we teach, we try different ways to teach topics and then judge
how successful the methods were. After several years, we have a compilation of
techniques in our teaching toolbox. New teachers are at a disadvantage because
they have fewer prior experiences to draw upon. Luckily, there is a group of
physicists and physics educators who are researching how students learn
physics, and have been able to show evidence of effective education practices
in physics. They field of study is called PER: Physics Education Research. I
asked Chandralekha Singh, one of the leaders in PER, to summarize some of the
most relevant PER findings and her response follows.


title: Robust Recognition of Simultaneous Speech By a Mobile Robot

abstract:
  This paper describes a system that gives a mobile robot the ability to
perform automatic speech recognition with simultaneous speakers. A microphone
array is used along with a real-time implementation of Geometric Source
Separation and a post-filter that gives a further reduction of interference
from other sources. The post-filter is also used to estimate the reliability of
spectral features and compute a missing feature mask. The mask is used in a
missing feature theory-based speech recognition system to recognize the speech
from simultaneous Japanese speakers in the context of a humanoid robot.
Recognition rates are presented for three simultaneous speakers located at 2
meters from the robot. The system was evaluated on a 200 word vocabulary at
different azimuths between sources, ranging from 10 to 90 degrees. Compared to
the use of the microphone array source separation alone, we demonstrate an
average reduction in relative recognition error rate of 24% with the
post-filter and of 42% when the missing features approach is combined with the
post-filter. We demonstrate the effectiveness of our multi-source microphone
array post-filter and the improvement it provides when used in conjunction with
the missing features theory.


title: Random Walks in a Sparse Random Environment

abstract:
  We introduce random walks in a sparse random environment on $\mathbb Z$ and
investigate basic asymptotic properties of this model, such as
recurrence-transience, asymptotic speed, and limit theorems in both the
transient and recurrent regimes. The new model combines features of several
existing models of random motion in random media and admits a transparent
physical interpretation. More specifically, a random walk in a sparse random
environment can be characterized as a "locally strong" perturbation of a simple
random walk by a random potential induced by "rare impurities," which are
randomly distributed over the integer lattice. Interestingly, in the critical
(recurrent) regime, our model generalizes Sinai's scaling of $(\log n)^2$ for
the location of the random walk after $n$ steps to $(\log n)^\alpha,$ where
$\alpha>0$ is a parameter determined by the distribution of the distance
between two successive impurities. Similar scaling factors have appeared in the
literature in different contexts and have been discussed in [28] and [30].