title: Four-dimensional weakly self-avoiding walk with contact self-attraction

abstract:
  We consider the critical behaviour of the continuous-time weakly
self-avoiding walk with contact self-attraction on $\mathbb{Z}^4$, for
sufficiently small attraction. We prove that the susceptibility and correlation
length of order $p$ (for any $p>0$) have logarithmic corrections to mean field
scaling, and that the critical two-point function is asymptotic to a multiple
of $|x|^{-2}$. This shows that small contact self-attraction results in the
same critical behaviour as no contact self-attraction; a collapse transition is
predicted for larger self-attraction. The proof uses a supersymmetric
representation of the two-point function, and is based on a rigorous
renormalisation group method that has been used to prove the same results for
the weakly self-avoiding walk, without self-attraction.


title: Chiral Anomaly and Second Harmonic Generation in Weyl Semimetals

abstract:
  We study second harmonic generation in centrosymmetric Weyl semimetal with
broken time reversal symmetry. We calculate electric current density at the
double frequency of the propagating electromagnetic field in the presence of
applied constant magnetic field, using the method of kinetic equation for
electron distribution function. It is shown that the chiral anomaly
contribution to second harmonic generation in the lowest order is linearly
proportional to the applied magnetic field. The limit when the chiral anomaly
dominates over the Lorentz-type contribution to second harmonic generation is
discussed.


title: Minimal unsatisfiability and deficiency: recent developments

abstract:
  Starting with Aharoni and Linial in 1986, the deficiency delta(F) = c(F) -
n(F) >= 1 for minimally unsatisfiable clause-sets F, the difference of the
number of clauses and the number of variables, is playing an important role in
investigations into the structure of minimal unsatisfiability. The talk
belonging to this extended abstract, available at
http://cs.swan.ac.uk/~csoliver/papers.html#BORDEAUX2016 , gives a high-level
overview on recent developments.


title:
Accurate Reference Data for the Non-Additive Non-Interacting Kinetic
  Energy in Covalent Bonds

abstract:
  The non-additive non-interacting kinetic energy is calculated exactly for
fragments of H$_2$, Li$_2$, Be$_2$, C$_2$, N$_2$, F$_2$, and Na$_2$ within
partition density-functional theory. The resulting fragments are uniquely
determined and their sum reproduces the Kohn-Sham molecular density of the
corresponding XC functional. We compare the use of fractional orbital
occupation to the usual PDFT ensemble method for treating the fragment energies
and densities. We also compare Thomas-Fermi and von Weiz{\"a}cker approximate
kinetic energy functionals to the numerically exact solution and find
significant regions where the von Weiz{\"a}cker solution is nearly exact.


title:
Time-dependence of the threshold function in the perfect plasticity
  model

abstract:
  This paper discusses the time-dependence of the threshold function in the
perfect plasticity model. In physical terms, it is natural that the threshold
function depends on some unknown variable. Therefore, it is meaningful to
discuss the well-posedness of this function under the weaker assumption of
time-dependence. Time-dependence is also interesting from the viewpoint of the
abstract evolution equation. To prove the existence of a solution to the
perfect plasticity model, the recent abstract theory under the continuous class
with respect to time is used.


title: Mutually exclusive uncertainty relations

abstract:
  The uncertainty principle is one of the characteristic properties of quantum
theory based on incompatibility. Apart from the incompatible relation of
quantum states, mutually exclusiveness is another remarkable phenomenon in the
information-theoretic foundation of quantum theory. We investigate the role of
mutual exclusive physical states in the recent work of stronger uncertainty
relations for all incompatible observables by Mccone and Pati and generalize
the weighted uncertainty relation to the product form as well as their
multi-observable analogues. The new bounds capture both incompatibility and
mutually exclusiveness, and are tighter compared with the existing bounds.


title: Cancellations for Circle-valued Morse Functions via Spectral Sequences

abstract:
  In this article, a spectral sequence analysis of a filtered Novikov complex
$(\mathcal{N}_{\ast}(f),\Delta)$ over $\mathbb{Z}((t))$ is developed with the
goal of obtaining results relating the algebraic and dynamical settings.
Specifically, the unfolding of a spectral sequence of
$(\mathcal{N}_{\ast}(f),\Delta)$ and the cancellation of its modules is
associated to a one parameter family of circle valued Morse functions on a
surface and the dynamical cancellations of its critical points. The data of a
spectral sequence computed for $(\mathcal{N}_{\ast}(f),\Delta)$ is encoded in a
family of matrices $\Delta^r$ produced by the Spectral Sequence Sweeping
Algorithm (SSSA), which has as its initial input the differential $\Delta$. As
one turns the pages of the spectral sequence, differentials which are
isomorphisms produce cancellation of pairs of modules. Corresponding to these
cancellations, a family of circle-valued Morse functions $f^r$ is obtained by
successively removing the corresponding pairs of critical points of $f$. We
also keep track of all dynamical information on the birth and death of
connecting orbits between consecutive critical points, as well as periodic
orbits that arise within a family of negative gradient flows associated to
$f^r$.


title:
A Generalized Approach to Power Analysis for Local Average Treatment
  Effects

abstract:
  This study introduces a new approach to power analysis in the context of
estimating a local average treatment effect (LATE), where the study subjects
exhibit noncompliance with treatment assignment. As a result of distributional
complications in the LATE context, compared to the simple ATE context, there is
currently no standard method of power analysis for the LATE. Moreover, existing
methods and commonly used substitutes - which include instrumental variable
(IV), intent-to-treat (ITT), and scaled ATE power analyses - require specifying
generally unknown variance terms and/or rely upon strong and unrealistic
assumptions, thus providing unreliable guidance on the power of tests of the
LATE. This study develops a new approach that uses standardized effect sizes to
place bounds on the power for the most commonly used estimator of the LATE, the
Wald IV estimator, whereby variance terms and distributional parameters need
not be specified nor assumed. Instead, in addition to the effect size, sample
size, and error tolerance parameters, the only other parameter that must be
specified by the researcher is the compliance rate. Additional conditions can
also be introduced to further narrow the bounds on the power calculation. The
result is a generalized approach to power analysis in the LATE context that is
simple to implement.


title:
Dense core properties in the Infrared Dark cloud G14.225-0.506 revealed
  by ALMA

abstract:
  We have performed a dense core survey toward the Infrared Dark Cloud
G14.225-0.506 at 3 mm continuum emission with the Atacama Large
Millimeter/Submillimeter Array (ALMA). This survey covers the two hub-filament
systems with an angular resolution of $\sim3$\arcsec ($\sim0.03$ pc). We
identified 48 dense cores. Twenty out of the 48 cores are protostellar due to
their association with young stellar objects (YSOs) and/or X-ray point-sources,
while the other 28 cores are likely prestellar and unrelated with known IR or
X-ray emission. Using APEX 870 $\mu$m continuum emission, we also identified
the 18 clumps hosting these cores. Through virial analysis using the ALMA
N$_2$H$^+$ and VLA/Effelsberg NH$_3$ molecular line data, we found a decreasing
trend in the virial parameter with decreasing scales from filaments to clumps,
and then to cores. The virial parameters of $0.1-1.3$ in cores, indicate that
cores are likely undergoing dynamical collapse. The cumulative Core Mass
Function (CMF) for the prestellar cores candidates has a power law index of
$\alpha=1.6$, with masses ranging from 1.5 to 22 $M_\odot$. We find no massive
prestellar or protostellar cores. Previous studies suggest that massive O-tpye
stars have not been produced yet in this region. Therefore, high-mass stars
should be formed in the prestellar cores by accreting a significant amount of
gas from the surrounding medium. Another possibility is that low-mass YSOs
become massive by accreting from their parent cores that are fed by filaments.
These two possibilities might be consistent with the scenario of global
hierarchical collapse.


title:
Reviving the precision of multiple entangled probes in an open system by
  simple $\pi$-pulse sequences

abstract:
  Quantum metrology with entangled states in realistic noisy environments
always suffers from decoherence. Therefore, the measurement precision is
greatly reduced. Here we applied the dynamical decoupling method to protect the
$N$-qubit quantum metrology protocol and successfully revived the scaling of
the measurement precision as ${N^{-k}}$ with $k\in \left[{5/6,11/12}\right]$.
The degree of the precision revival, as determined by the noise spectrum
distribution, indicates that the performance of the protected protocol can be
further improved by controlling the noise spectrum. Such a protected protocol
is proved to be universal for entanglement-based quantum metrology in the pure
dephasing and relaxation noise, which should stimulate the development of
practical quantum metrology for weak signal detection of microscopic physics.


title:
The Phase-Contrast Imaging Instrument at the Matter in Extreme
  Conditions Endstation at LCLS

abstract:
  We describe the Phase-Contrast Imaging instrument at the Matter in Extreme
Conditions (MEC) endstation of the Linac Coherent Light Source. The instrument
can image phenomena with a spatial resolution of a few hundreds of nanometers
and at the same time reveal the atomic structure through X-ray diffraction,
with a temporal resolution better than 100 femtosecond. It was specifically
designed for studies relevant to High-Energy-Density Science and can monitor,
e.g., shock fronts, phase transitions, or void collapses. This versatile
instrument was commissioned last year and is now available to the MEC user
community.


title:
Near-infrared-enhanced charge state conversion for low power optical
  nanoscopy with nitrogen vacancy center in diamond

abstract:
  The near-infrared (NIR) optical pumped photophysics of nitrogen vacancy (NV)
center in diamond was experimentally studied by considering both the charge
state conversion and stimulated emission. We found that the NIR laser can help
to highly enhance the charge state conversion rate, which can be applied to
improve the performance of charge state depletion nanoscopy. Using a
doughnut-shaped visible laser beam and a Gaussian-shaped NIR laser beam for
charge state manipulation, we developed a low power charge state depletion
nanoscopy for NV center. A spatial resolution of 14 nm was achieved with the
depletion laser intensity approximately three orders lower than that used for
the stimulated emission depletion nanoscopy with NV center. With high spatial
resolution and low laser power, the nanoscopy can be used for nanoscale quantum
sensing with NV center. And our study on the charge state conversion can help
to further optimize the NV center spin state initialization and detection.


title: Exotic Looped Trajectories of Photons in Three-Slit Interference

abstract:
  The validity of the superposition principle and of Born's rule are
well-accepted tenants of quantum mechanics. Surprisingly, it has recently been
predicted that the intensity pattern formed in a three-slit experiment is
seemingly in contradiction with the predictions of the most conventional form
of the superposition principle when exotic looped trajectories are taken into
account. However, the probability of observing such paths is typically very
small and thus rendering them extremely difficult to measure. In this work, we
confirm the validity of Born's rule and present the first experimental
observation of these exotic trajectories as additional paths for the light by
directly measuring their contribution to the formation of optical interference
fringes. We accomplish this by enhancing the electromagnetic near-fields in the
vicinity of the slits through the excitation of surface plasmons. This process
effectively increases the probability of occurrence of these exotic
trajectories, demonstrating that they are related to the near-field component
of the photon's wavefunction.


title: Prospects for Neutrino Spin Coherence in Supernovae

abstract:
  We present neutrino bulb model simulations of Majorana neutrino coherent spin
transformation (i.e., neutrino-antineutrino transformation), coupled to
neutrino flavor evolution, for conditions corresponding to the neutronization
burst epoch of an Oxygen-Neon-Magnesium (O-Ne-Mg) core collapse supernova.
Significant neutrino spin transformation in, for example, the neutronization
burst, could alter the fluences of neutrinos and antineutrinos in a way which
is potentially detectable for a Galactic core collapse supernova. Our
calculations for the first time incorporate geometric dilution in the spin
evolution of the neutrinos and combine two-flavor and three-flavor evolution
with spin mixing physics. We find that significant spin transformations can
occur, but only with a large neutrino luminosity and an electron fraction
($Y_e$) profile which facilitates adiabatic conditions for the spin-channel
resonance. Using our adopted parameters of neutrino energy spectra, luminosity,
density and $Y_e$ profiles, our calculations require an unrealistically large
neutrino rest mass to sustain the spin transformation. It is an open question
whether examining different density profiles or incorporating other sources of
nonlinear feedback, such as $Y_e$ feedback, could mitigate this need. We find
that spin transformations are not sensitive to the flavor structure of
neutrinos, i.e., the spin transformations occur regardless of whether we
simulate two- or three-flavor transformations. In the two-flavor case, spin
transformations were insensitive to the choice of solar or atmospheric
mass-squared splitting as well as the choice of the Majorana phase.
Importantly, our three-flavor simulations, as well as our two-flavor
simulations done with the atmospheric mass-squared splitting, show that the
inclusion of spin degrees of freedom can significantly and qualitatively alter
neutrino flavor evolution.


title: Lattice Dirac Fermions on a Simplicial Riemannian Manifold

abstract:
  The lattice Dirac equation is formulated on a simplicial complex which
approximates a smooth Riemann manifold by introducing a lattice vierbein on
each site and a lattice spin connection on each link. Care is taken so the
construction applies to any smooth D-dimensional Riemannian manifold that
permits a spin connection. It is tested numerically in 2D for the projective
sphere ${\mathbb S}^2$ in the limit of an increasingly refined sequence of
triangles. The eigenspectrum and eigenvectors are shown to converge rapidly to
the exact result in the continuum limit. In addition comparison is made with
the continuum Ising conformal field theory on ${\mathbb S}^2$. Convergence is
tested for the two point, $\langle \epsilon(x_1) \epsilon(x_2) \rangle$, and
the four point, $\langle \sigma(x_1) \epsilon(x_2) \epsilon(x_3 )\sigma(x_4)
\rangle $, correlators for the energy, $\epsilon(x) = i \bar \psi(x)\psi(x)$,
and twist operators, $\sigma(x)$, respectively.


title:
New crystal structure prediction of fully hydrogenated borophene by
  first principles calculations

abstract:
  New crystal structures of fully hydrogenated borophene (borophane) have been
predicted by first principles calculation. Comparing with the chair-like
borophane (C-boropane) that has been reported in literature, we obtained four
new borophane conformers with much lower total-energy. The most stable one,
washboard-like borophane (W-borophane), has energy about 113.41 meV/atom lower
than C-borophane. In order to explain the relative stability of different
borophane conformers, the atom configuration, density of states, charge
transfer, charge density distribution and defect formation energy of B-H dimer
have been calculated. The results show that the charge transfer from B atoms to
H atoms is crucial for the stability of borophane. In different borophane
conformers, the bonding characteristics between B and H atoms are similar, but
the B-B bonds in W-borophane are much stronger than that in C-borophane or
other structures. In addition, we examined the dynamical stability of borophane
conformers by phonon dispersions and found that the four new conformers are all
dynamically stable. Finally the mechanical properties of borophane conformers
along an arbitrary direction have been discussed. W-borophane possesses unique
electronic structure (Dirac cone), good stability and superior mechanical
properties. W-borophane has broad perspective for nano electronic device.


title: Iterative Inversion of Deformation Vector Fields with Feedback Control

abstract:
  Purpose: Often, the inverse deformation vector field (DVF) is needed together
with the corresponding forward DVF in 4D reconstruction and dose calculation,
adaptive radiation therapy, and simultaneous deformable registration. This
study aims at improving both accuracy and efficiency of iterative algorithms
for DVF inversion, and advancing our understanding of divergence and latency
conditions. Method: We introduce a framework of fixed-point iteration
algorithms with active feedback control for DVF inversion. Based on rigorous
convergence analysis, we design control mechanisms for modulating the inverse
consistency (IC) residual of the current iterate, to be used as feedback into
the next iterate. The control is designed adaptively to the input DVF with the
objective to enlarge the convergence area and expedite convergence. Three
particular settings of feedback control are introduced: constant value over the
domain throughout the iteration; alternating values between iteration steps;
and spatially variant values. We also introduce three spectral measures of the
displacement Jacobian for characterizing a DVF. These measures reveal the
critical role of what we term the non-translational displacement component
(NTDC) of the DVF. We carry out inversion experiments with an analytical DVF
pair, and with DVFs associated with thoracic CT images of 6 patients at end of
expiration and end of inspiration. Results: NTDC-adaptive iterations are shown
to attain a larger convergence region at a faster pace compared to previous
non-adaptive DVF inversion iteration algorithms. By our numerical experiments,
alternating control yields smaller IC residuals and inversion errors than
constant control. Spatially variant control renders smaller residuals and
errors by at least an order of magnitude, compared to other schemes, in no more
than 10 steps. Inversion results also show remarkable quantitative agreement
with analysis-based predictions. Conclusion: Our analysis captures properties
of DVF data associated with clinical CT images, and provides new understanding
of iterative DVF inversion algorithms with a simple residual feedback control.
Adaptive control is necessary and highly effective in the presence of non-small
NTDCs. The adaptive iterations or the spectral measures, or both, may
potentially be incorporated into deformable image registration methods.


title: Classifying the Arithmetical Complexity of Teaching Models

abstract:
  This paper classifies the complexity of various teaching models by their
position in the arithmetical hierarchy. In particular, we determine the
arithmetical complexity of the index sets of the following classes: (1) the
class of uniformly r.e. families with finite teaching dimension, and (2) the
class of uniformly r.e. families with finite positive recursive teaching
dimension witnessed by a uniformly r.e. teaching sequence. We also derive the
arithmetical complexity of several other decision problems in teaching, such as
the problem of deciding, given an effective coding $\{\mathcal L_0,\mathcal
L_1,\mathcal L_2,\ldots\}$ of all uniformly r.e. families, any $e$ such that
$\mathcal L_e = \{L^e_0,L^e_1,\ldots,\}$, any $i$ and $d$, whether or not the
teaching dimension of $L^e_i$ with respect to $\mathcal L_e$ is upper bounded
by $d$.


title:
Importance of volume corrections on the net-charge distributions at the
  RHIC BES energies

abstract:
  The paper presents my recent investigations of volume corrections on the
cumulant products of net-charge distributions in statistical model,
corresponding to the data reported by the STAR collaboration. The corrected
statistical expectations, under simple Poisson approximations, can reasonably
explain the data measured in experiment. The results indicate that volume
corrections play crucial role in event-by-event multiplicity fluctuation
studies.


title:
Bounds on Herglotz functions and fundamental limits of broadband passive
  quasi-static cloaking

abstract:
  Using a sum rule, we derive new bounds on Herglotz functions that generalize
those given in (Gustafson and Sj\"oberg 2010) and (Bernland, Luger and
Gustafson 2011). These bounds apply to a wide class of linear passive systems
such as electromagnetic passive materials. Among these bounds, we describe the
optimal ones and also discuss their meaning in various physical situations like
in the case of a transparency window, where we exhibit sharp bounds. Then, we
apply these bounds in the context of broadband passive cloaking in the
quasi-static regime to negatively answer the following challenging question: is
it possible to construct a passive cloaking device that cloaks an object over a
whole frequency band? Our rigorous approach, although limited to quasi-statics,
gives quantitative limitations on the cloaking effect over a finite frequency
range by providing inequalities on the polarizabilty tensor associated with the
cloaking device. We emphasize that our results hold for a cloak or object of
any geometrical shape.


title:
Muon spin rotation and infrared spectroscopy study of magnetism and
  superconductivity in Ba$ _{1-x} $K$ _{x} $Fe$ _{2} $As$ _{2} $

abstract:
  Using muon spin rotation and infrared spectroscopy we study the relation
between magnetism and superconductivity in Ba$ _{1-x} $K$ _{x} $Fe$ _{2} $As$
_{2} $ single crystals from the underdoped to the slightly overdoped regime. We
find that the Fe magnetic moment is only moderately suppressed in most of the
underdoped region where it decreases more slowly than the N\'{e}el-temperature,
$ T^{\mathrm{N}} $. This applies for both the total Fe moment obtained from
muon spin rotation and for the itinerant component that is deduced from the
spectral weight of the spin-density-wave pair breaking peak in the infrared
response. In the moderately underdoped region, superconducting and static
magnetic orders co-exist on the nano-scale and compete for the same electronic
states. The static magnetic moment disappears rather sharply near optimal
doping, however, in the slightly overdoped region there is still an enhancement
or slowing down of spin fluctuations in the superconducting state. Similar to
the gap magnitude reported from specific heat measurements, the superconducting
condensate density is nearly constant in the optimally- and slightly overdoped
region, but exhibits a rather pronounced decrease on the underdoped side.
Several of these observations are similar to the phenomenology in the electron
doped counterpart Ba(Fe$ _{1-y} $Co$ _{y} $)$ _{2} $As$ _{2} $.


title: Magnetoresistance and robust resistivity plateau in MoAs2

abstract:
  We have grown the MoAs$_2$ single crystal which crystallizes in a monoclinic
structure with C2/m space group. Transport measurements show that MoAs$_2$
displays a metallic behavior at zero field and undergoes a
metal-to-semiconductor crossover at low temperatures when the applied magnetic
field is over 5 T. A robust resistivity plateau appears below 18 K and persists
for the field up to 9 T. A large positive magnetoresistance (MR), reaching
about 2600\% at 2 K and 9 T, is observed when the field is perpendicular to the
current.The MR becomes negative below 40 K when the field is rotated to be
parallel to the current. The Hall resistivity shows the non-linear
field-dependence below 70 K. The analysis using two-band model indicates a
compensated electron-hole carrier density at low temperatures. A combination of
the breakdown of Kohler's rule, the abnormal drop and the cross point in Hall
data implies that a possible Lifshitz transition has occurred between 30 K and
60 K, likely driving the compensated electron-hole density, the large MR as
well as the metal-semiconductor transition in MoAs$_2$. Our results indicate
that the family of centrosymmetric transition-metal dipnictides has rich
transport behavior which can in general exhibit variable metallic and
topological features.


title: A Direct Construction of Non-Transitive Dice Sets

abstract:
  In this paper, we give a direct construction for a set of dice realizing any
given tournament $T$. The construction for a tournament with $n$ vertices
requires a number of sides on the order of $n$, which appears to be the best
general construction to date. Our construction relies only on a standard
theorem from graph theory.


title:
Quantifying the Interstellar Medium and Cosmic Rays in the MBM 53, 54,
  and 55 Molecular Clouds and the Pegasus Loop using Fermi-LAT Gamma-ray
  Observations

abstract:
  A study of the interstellar medium (ISM) and cosmic rays (CRs) using Fermi
Large Area Telescope (LAT) data, in a region encompassing the nearby molecular
clouds MBM 53, 54, and 55 and a far-infrared loop-like structure in Pegasus, is
reported. By comparing Planck dust thermal emission model with Fermi-LAT
gamma-ray data, it was found that neither the dust radiance (R) nor the dust
opacity at 353 GHz (tau353) were proportional to the total gas column density
N(Htot) primarily because N(Htot)/R and N(Htot)/tau353 depend on the dust
temperature (Td). The N(Htot) distribution was evaluated using gamma-ray data
by assuming the regions of high Td} to be dominated by optically thin atomic
hydrogen (HI) and by employing an empirical linear relation of N(Htot)/R to Td.
It was determined that the mass of the gas not traced by the 21-cm or 2.6-mm
surveys is ~25% of the mass of HI in the optically thin case and is larger than
the mass of the molecular gas traced by carbon monoxide by a factor of up to 5.
The measured gamma-ray emissivity spectrum is consistent with a model based on
CR spectra measured at the Earth and the nuclear enhancement factor of <=1.5.
It is, however, lower than local HI emissivities reported by previous Fermi-LAT
studies employing different analysis methods and assumptions on ISM properties
by 15%-20% in energies below a few GeV, even if we take account of the
statistical and systematic uncertainties. The origin of the discrepancy is also
discussed.


title: Word Embeddings to Enhance Twitter Gang Member Profile Identification

abstract:
  Gang affiliates have joined the masses who use social media to share thoughts
and actions publicly. Interestingly, they use this public medium to express
recent illegal actions, to intimidate others, and to share outrageous images
and statements. Agencies able to unearth these profiles may thus be able to
anticipate, stop, or hasten the investigation of gang-related crimes. This
paper investigates the use of word embeddings to help identify gang members on
Twitter. Building on our previous work, we generate word embeddings that
translate what Twitter users post in their profile descriptions, tweets,
profile images, and linked YouTube content to a real vector format amenable for
machine learning classification. Our experimental results show that pre-trained
word embeddings can boost the accuracy of supervised learning algorithms
trained over gang members social media posts.


title:
Strong-coupling Properties of a $p$-wave Interacting Fermi Gas on the
  Viewpoint of Specific Heat at Constant Volume

abstract:
  We theoretically investigate the specific heat $C_V$ at constant volume in
the normal state of a $p$-wave interacting Fermi gas. Including fluctuations in
the $p$-wave Cooper channel within the framework of the strong-coupling theory
developed by Nozi\`eres and Schmitt-Rink, we clarify how $C_V$ as a function of
temperature varies, as one moves from the weak-coupling regime to the
strong-coupling limit. In the weak-coupling regime, $C_V$ is shown to be
enhanced by $p$-wave pairing fluctuations, near the superfluid phase transition
temperature $T_{\rm c}$. Similar enhancement of $C_V(T\simeq T_{\rm c})$ is
also obtained in the strong-coupling regime, which, however, reflects that
system is close an ideal Bose gas of $p$-wave two-body bound molecules. Using
these results, we classify the normal state into (1) the normal Fermi gas
regime, (2) the $p$-wave molecular Bose gas regime, and (3) the region between
the two, where $p$-wave pairing fluctuations are dominant. Since the current
experiments can only access the normal phase of a $p$-wave interacting Fermi
gas, our results would be useful for experiments to understand strong-coupling
properties of this Fermi system above $T_{\rm c}$.


title: Relative Weak Injectivity for C*-algebras

abstract:
  We study the order theoretic properties of relative weak injectivity, w.r.i.,
in short, in the category of C*-algebras. We prove that Arveson's extension
theorem, with additional order assumption on the morphisms, is tightly
connected with relative weak injectivity. We prove that (2,3)-Riesz-Arveson
property, defined below, is equivalent to w.r.i. Likewise tight Riesz
interpolation property yields another characterization of w.r.i. We exhibit,
with examples, that these C*-algebraic properties fail in general operator
systems. Several order theoretic characterization of Connes' embedding problem
is given.


title: Observations of the Structure and Dynamics of the Inner M87 Jet

abstract:
  M87 is the best source in which to study a jet at high resolution in
gravitational units because it has a very high mass black hole and is nearby.
The angular size of the black hole is second only to Sgr A*, which does not
have a strong jet. The jet structure is edge brightened with a wide opening
angle base and a weak counterjet. We have roughly annual observations for 17
years plus intensive monitoring at three week intervals for a year and five day
intervals for 2.5 months made with the Very Long Baseline Array (VLBA) at 43
GHz. The inner jet shows very complex dynamics, with apparent motions both
along and across the jet. Speeds from zero to over 2c are seen, with
acceleration observed over the first 3 milli-arcseconds. The counterjet
decreases in brightness much more rapidly than the main jet, as is expected
from relativistic beaming in an accelerating jet oriented near the
line-of-sight. Details of the structure and dynamics are discussed. The roughly
annual observations show side-to-side motion of the whole jet with a
characteristic time scale of about 9 years.


title:
Hybridization gap in the heavy-fermion compound UPd$_2$Al$_3$ via
  quasiparticle scattering spectroscopy

abstract:
  We present results from point-contact spectroscopy of the antiferromagnetic
heavy-fermion superconductor UPd$_2$Al$_3$: conductance spectra are taken from
single crystals with two major surface orientations as a function of
temperature and magnetic field, and analyzed using a theory of co-tunneling
into an Anderson lattice. Spectroscopic signatures are clearly identified
including the distinct asymmetric double-peak structure arising from the
opening of a hybridization gap when a coherent heavy Fermi liquid is formed.
Both the hybridization gap, found to be 7.2 $\pm$ 0.3 meV at 4 K, and the
conductance enhancement above a flat background decrease upon increasing
temperature. While the hybridization gap is extrapolated to remain finite up to
$\sim$28 K, close to the temperature around which the magnetic susceptibility
displays a broad peak, the conductance enhancement vanishes at $\sim$18 K,
slightly above the antiferromagnetic transition temperature ($T_\textrm{N}$
$\approx$ 14 K). This rapid decrease of the conductance enhancement is
understood as a consequence of the junction drifting away from the ballistic
regime due to increased scattering off magnons associated with the localized U
5$f$ electrons. This shows that while the hybridization gap opening is not
directly associated with the antiferromagnetic ordering, its visibility in the
conductance is greatly affected by the temperature-dependent magnetic
excitations. Our findings are not only consistent with the 5$f$ dual-nature
picture in the literature but also shed new light on the interplay between the
itinerant and localized electrons in UPd$_2$Al$_3$.


title:
A Review of 40 Years of Cognitive Architecture Research: Core Cognitive
  Abilities and Practical Applications

abstract:
  In this paper we present a broad overview of the last 40 years of research on
cognitive architectures. Although the number of existing architectures is
nearing several hundred, most of the existing surveys do not reflect this
growth and focus on a handful of well-established architectures. Thus, in this
survey we wanted to shift the focus towards a more inclusive and high-level
overview of the research on cognitive architectures. Our final set of 84
architectures includes 49 that are still actively developed, and borrow from a
diverse set of disciplines, spanning areas from psychoanalysis to neuroscience.
To keep the length of this paper within reasonable limits we discuss only the
core cognitive abilities, such as perception, attention mechanisms, action
selection, memory, learning and reasoning. In order to assess the breadth of
practical applications of cognitive architectures we gathered information on
over 900 practical projects implemented using the cognitive architectures in
our list. We use various visualization techniques to highlight overall trends
in the development of the field. In addition to summarizing the current
state-of-the-art in the cognitive architecture research, this survey describes
a variety of methods and ideas that have been tried and their relative success
in modeling human cognitive abilities, as well as which aspects of cognitive
behavior need more research with respect to their mechanistic counterparts and
thus can further inform how cognitive science might progress.


title: Ordered Kinematic Endpoints for 5-body Cascade Decays

abstract:
  We present expressions for the kinematic endpoints of 5-body cascade decay
chains proceeding through all possible combinations of 2-body and 3-body
decays, with one stable invisible particle in the final decay stage. When an
invariant mass can be formed in multiple ways by choosing different final state
particles from a common vertex, we introduce techniques for finding the
sub-leading endpoints for all indistinguishable versions of the invariant mass.
In contrast to short decay chains, where sub-leading endpoints are linearly
related to the leading endpoints, we find that in 5-body decays, they provide
additional independent constraints on the mass spectrum.


title:
Surpassing the no-cloning limit with a heralded hybrid linear amplifier
  for coherent states

abstract:
  The no-cloning theorem states that an unknown quantum state cannot be cloned
exactly and deterministically due to the linearity of quantum mechanics.
Associated with this theorem is the quantitative no-cloning limit that sets an
upper bound to the quality of the generated clones. However, this limit can be
circumvented by abandoning determinism and using probabilistic methods. Here,
we report an experimental demonstration of probabilistic cloning of arbitrary
coherent states that clearly surpasses the no-cloning limit. Our scheme is
based on a hybrid linear amplifier that combines an ideal deterministic linear
amplifier with a heralded measurement-based noiseless amplifier. We demonstrate
the production of up to five clones with the fidelity of each clone clearly
exceeding the corresponding no-cloning limit. Moreover, since successful
cloning events are heralded, our scheme has the potential to be adopted in
quantum repeater, teleportation and computing applications.


title: Shortcuts to adiabaticity for quantum annealing

abstract:
  We study the Ising Hamiltonian with a transverse field term to simulate the
quantum annealing. Using shortcuts to adiabaticity, we design the time
dependence of the Hamiltonian. The dynamical invariant is obtained by the
mean-field ansatz, and the Hamiltonian is designed by the inverse engineering.
We show that the time dependence of physical quantities such as the
magnetization is independent of the speed of the Hamiltonian variation in the
infinite-range model. We also show that rotating transverse magnetic fields are
useful to achieve the ideal time evolution.


title: Fast Low-rank Shared Dictionary Learning for Image Classification

abstract:
  Despite the fact that different objects possess distinct class-specific
features, they also usually share common patterns. This observation has been
exploited partially in a recently proposed dictionary learning framework by
separating the particularity and the commonality (COPAR). Inspired by this, we
propose a novel method to explicitly and simultaneously learn a set of common
patterns as well as class-specific features for classification with more
intuitive constraints. Our dictionary learning framework is hence characterized
by both a shared dictionary and particular (class-specific) dictionaries. For
the shared dictionary, we enforce a low-rank constraint, i.e. claim that its
spanning subspace should have low dimension and the coefficients corresponding
to this dictionary should be similar. For the particular dictionaries, we
impose on them the well-known constraints stated in the Fisher discrimination
dictionary learning (FDDL). Further, we develop new fast and accurate
algorithms to solve the subproblems in the learning step, accelerating its
convergence. The said algorithms could also be applied to FDDL and its
extensions. The efficiencies of these algorithms are theoretically and
experimentally verified by comparing their complexities and running time with
those of other well-known dictionary learning methods. Experimental results on
widely used image datasets establish the advantages of our method over
state-of-the-art dictionary learning methods.


title: Learning Likely Invariants to Explain Why a Program Fails

abstract:
  Debugging is difficult. Recent studies show that automatic bug localization
techniques have limited usefulness. One of the reasons is that programmers
typically have to understand why the program fails before fixing it. In this
work, we aim to help programmers understand a bug by automatically generating
likely invariants which are violated in the failed tests. Given a program with
an initial assertion and at least one test case failing the assertion, we first
generate random test cases, identify potential bug locations through bug
localization, and then generate program state mutation based on active learning
techniques to identify a predicate "explaining" the cause of the bug. The
predicate is a classifier for the passed test cases and failed test cases. Our
main contribution is the application of invariant learning for bug explanation,
as well as a novel approach to overcome the problem of lack of test cases in
practice. We apply our method to real-world bugs and show the generated
invariants are often correlated to the actual bug fixes.


title:
A Petrov-Galerkin Spectral Element Method for Fractional Elliptic
  Problems

abstract:
  We develop a new $C^{\,0}$-continuous Petrov-Galerkin spectral element method
for one-dimensional fractional elliptic problems of the form
${}_{0}{\mathcal{D}}_{x}^{\alpha} u(x) - \lambda u(x) = f(x)$, $\alpha \in
(1,2]$, subject to homogeneous boundary conditions. We employ the standard
(modal) spectral element bases and the Jacobi poly-fractonomials as the test
functions [1]. We formulate a new procedure for assembling the global linear
system from elemental (local) mass and stiffness matrices. The Petrov-Galerkin
formulation requires performing elemental (local) construction of mass and
stiffness matrices in the standard domain only once. Moreover, we efficiently
obtain the non-local (history) stiffness matrices, in which the non-locality is
presented analytically for uniform grids. We also investigate two distinct
choices of basis/test functions: i) local basis/test functions, and ii) local
basis with global test functions. We show that the former choice leads to a
better-conditioned system and accuracy. We consider smooth and singular
solutions, where the singularity can occur at boundary points as well as in the
interior domain. We also construct two non-uniform grids over the whole
computational domain in order to capture singular solutions. Finally, we
perform a systematic numerical study of non-local effects via full and partial
history fading in order to further enhance the efficiency of the scheme.


title:
Systems of Delay Differential Equations: Analysis of a model with
  feedback

abstract:
  Self-regulatory models are common in nature, as described e.g. in
(\cite{mur}), (\cite{ha}) and (\cite{Gb}).\\ Let us consider a system made up
of a number of glands as a motivation. Each gland secretes a hormone that
allows secretion in the {next} gland, which successively generates another
hormone to stimulate the next one and so on. In the end, a final hormone is
released which, by increasing its concentration, will inhibit the secretion of
previous hormones that allowed the production process. This generates the decay
of this hormone to a minimum threshold that re-activates the cycle again.\\
This behavior can be seen in other biochemical processes, such as enzymatic or
bacterial models.\\ Topological degree is a useful tool to find stable
equilibria in a wide variety of models with constant parameters and,
furthermore, allows to deduce the existence of periodic solutions when the
constant parameters are replaced by periodic functions.


title:
The physical environment around IRAS 17599-2148: infrared dark cloud and
  bipolar nebula

abstract:
  We present a multi-scale and multi-wavelength study to investigate the star
formation process around IRAS 17599$-$2148 that is part of an elongated
filamentary structure (EFS) (extension $\sim$21 pc) seen in the {\it Herschel}
maps. Using the {\it Herschel} data analysis, at least six massive clumps
(M$_{clump}$ $\sim$777 -- 7024 M$_{\odot}$) are found in the EFS with a range
of temperature and column density of $\sim$16--39~K and
$\sim$0.6--11~$\times$~10$^{22}$ cm$^{-2}$ (A$_{V}$ $\sim$7--117 mag),
respectively. The EFS hosts cold gas regions (i.e. infrared dark cloud) without
any radio detection and a bipolar nebula (BN) linked with the H\,{\sc ii}
region IRAS 17599$-$2148, tracing two distinct environments inferred through
the temperature distribution and ionized emission. Based on virial analysis and
higher values of self-gravitating pressure, the clumps are found unstable
against gravitational collapse. We find 474 young stellar objects (YSOs) in the
selected region and $\sim$72\% of these YSOs are found in the clusters
distributed mainly toward the clumps in the EFS. These YSOs might have
spontaneously formed due to processes not related to the expanding H\,{\sc ii}
region. At the edges of BN, four additional clumps are also associated with
YSOs clusters, which appear to be influenced by the expanding H\,{\sc ii}
region. The most massive clump in the EFS contains two compact radio sources
traced in the GMRT 1.28 GHz map and a massive protostar candidate, IRS~1 prior
to an ultracompact H\,{\sc ii} phase. Using the VLT/NACO near-infrared images,
IRS~1 is resolved with a jet-like feature within a 4200~AU scale.


title:
Causal Network Learning from Multiple Interventions of Unknown
  Manipulated Targets

abstract:
  In this paper, we discuss structure learning of causal networks from multiple
data sets obtained by external intervention experiments where we do not know
what variables are manipulated. For example, the conditions in these
experiments are changed by changing temperature or using drugs, but we do not
know what target variables are manipulated by the external interventions. From
such data sets, the structure learning becomes more difficult. For this case,
we first discuss the identifiability of causal structures. Next we present a
graph-merging method for learning causal networks for the case that the sample
sizes are large for these interventions. Then for the case that the sample
sizes of these interventions are relatively small, we propose a data-pooling
method for learning causal networks in which we pool all data sets of these
interventions together for the learning. Further we propose a re-sampling
approach to evaluate the edges of the causal network learned by the
data-pooling method. Finally we illustrate the proposed learning methods by
simulations.


title:
Multiresolution decomposition of quantum field theories using wavelet
  bases

abstract:
  We investigate both theoretical and computational aspects of using wavelet
bases to decouple physics on different scales in quantum field theory.


title: Can Active Memory Replace Attention?

abstract:
  Several mechanisms to focus attention of a neural network on selected parts
of its input or memory have been used successfully in deep learning models in
recent years. Attention has improved image classification, image captioning,
speech recognition, generative models, and learning algorithmic tasks, but it
had probably the largest impact on neural machine translation.
  Recently, similar improvements have been obtained using alternative
mechanisms that do not focus on a single part of a memory but operate on all of
it in parallel, in a uniform way. Such mechanism, which we call active memory,
improved over attention in algorithmic tasks, image processing, and in
generative modelling.
  So far, however, active memory has not improved over attention for most
natural language processing tasks, in particular for machine translation. We
analyze this shortcoming in this paper and propose an extended model of active
memory that matches existing attention models on neural machine translation and
generalizes better to longer sentences. We investigate this model and explain
why previous active memory models did not succeed. Finally, we discuss when
active memory brings most benefits and where attention can be a better choice.


title: The Conley-Zehnder Index of Brownian Paths on Sp(2, R)

abstract:
  We investigate the probability distribution of Conley-Zehnder indices
associated with Brownian random paths on Sp(2n, R) that start at the identity.
In the case of n = 1, we prove that the distribution has the same moment
asymptotics as the standard random walk on the real line. We also present
numerical evidence suggesting that the same asymptotics should hold for general
n.


title: Effective bi-immunity and randomness

abstract:
  We study the relationship between randomness and effective bi-immunity.
Greenberg and Miller have shown that for any oracle X, there are arbitrarily
slow-growing DNR functions relative to X that compute no ML random set. We show
that the same holds when ML randomness is replaced with effective bi-immunity.
It follows that there are sequences of effective Hausdorff dimension 1 that
compute no effectively bi-immune set.
  We also establish an important difference between the two properties. The
class Low(MLR, EBI) of oracles relative to which every ML random is effectively
bi-immune contains the jump-traceable sets, and is therefore of cardinality
continuum.


title:
Joint Target Detection and Tracking in Multipath Environment: A
  Variational Bayesian Approach

abstract:
  We consider multitarget detection and tracking problem for a class of
multipath detection system where one target may generate multiple measurements
via multiple propagation paths, and the association relationship among targets,
measurements and propagation paths is unknown. In order to effectively utilize
multipath measurements from one target to improve detection and tracking
performance, a tracker has to handle high-dimensional estimation of latent
variables including target active/dormant meta-state, target kinematic state,
and multipath data association. Based on variational Bayesian inference, we
propose a novel joint detection and tracking algorithm that incorporates
multipath data association, target detection and target state estimation in a
unified Bayesian framework. The posterior probabilities of these latent
variables are derived in a closed-form iterative manner, which is effective for
reducing the performance deterioration caused by the coupling between
estimation errors and identification errors. Loopy belief propagation is
exploited to approximately calculate the probability of multipath data
association, saving the computational cost significantly. Simulation results of
over-the-horizon radar multitarget tracking show that the proposed algorithm
outperforms multihypothesis multipath track fusion and multi-detection
(hypothesis-oriented) multiple hypothesis tracker, especially under low
signal-to-noise ratio circumstance.


title: Gap-bridging enhancement of modified Urca processes in nuclear matter

abstract:
  In nuclear matter at neutron-star densities and temperatures, Cooper pairing
leads to the formation of a gap in the nucleon excitation spectra resulting in
exponentially strong Boltzmann suppression of many transport coefficients.
Previous calculations have shown evidence that density oscillations of
sufficiently large amplitude can overcome this suppression for flavor-changing
$\beta$ processes, via the mechanism of "gap bridging". We address the
simplifications made in that initial work, and show that gap bridging can
counteract Boltzmann suppression of neutrino emissivity for the realistic case
of modified Urca processes in matter with $^3P_2$ neutron pairing.


title:
Impact of International Cooperation for Sustaining Space-Science
  Programs

abstract:
  Space-science programs provide a wide range of application to a nation's key
sectors of development: science-technology infrastructure, education, economy
and national security. However, the cost of sustaining a space-science program
has discouraged developing nations from participating in space activities,
while developed nations have steadily cut down their space-science budget in
past decade. In this study I investigate the role of international cooperation
in building ambitious space-science programs, particularly in the context of
developing nations. I devise a framework to quantify the impact of
international collaborations in achieving the space-science goals as well as in
enhancing the key sectors of development of a nation. I apply this framework on
two case studies, (i) Indian Space Research Organization - a case of
space-science program from a developing nation that has historically engaged in
international collaborations, and (ii) International Space Station - a case for
a long term collaboration between matured space-science programs. My study
concludes that international cooperation in space can significantly enhance
scope of science goals, but has relatively little return of investment towards
science education and national security. I also highlight limitations of such
space diplomacy in the case of China and SAARC nations, and list criteria for
future investigation and case studies.


title: Exploiting Structure Sparsity for Covariance-based Visual Representation

abstract:
  The past few years have witnessed increasing research interest on
covariance-based feature representation. A variety of methods have been
proposed to boost its efficacy, with some recent ones resorting to nonlinear
kernel technique. Noting that the essence of this feature representation is to
characterise the underlying structure of visual features, this paper argues
that an equally, if not more, important approach to boosting its efficacy shall
be to improve the quality of this characterisation. Following this idea, we
propose to exploit the structure sparsity of visual features in skeletal human
action recognition, and compute sparse inverse covariance estimate (SICE) as
feature representation. We discuss the advantage of this new representation on
dealing with small sample, high dimensionality, and modelling capability.
Furthermore, utilising the monotonicity property of SICE, we efficiently
generate a hierarchy of SICE matrices to characterise the structure of visual
features at different sparsity levels, and two discriminative learning
algorithms are then developed to adaptively integrate them to perform
recognition. As demonstrated by extensive experiments, the proposed
representation leads to significantly improved recognition performance over the
state-of-the-art comparable methods. In particular, as a method fully based on
linear technique, it is comparable or even better than those employing
nonlinear kernel technique. This result well demonstrates the value of
exploiting structure sparsity for covariance-based feature representation.


title: Weak prediction principles

abstract:
  We prove the consistency of the failure of the weak diamond $\Phi_\lambda$ at
strongly inaccessible cardinals. On the other hand, we show that the very weak
diamond $\Psi_\lambda$ is equivalent to the statement $2^{<\lambda}<2^\lambda$
and hence holds at every strongly inaccessible cardinal.


title:
Estimator Augmentation with Applications in High-Dimensional Group
  Inference

abstract:
  To make inference about a group of parameters on high-dimensional data, we
develop the method of estimator augmentation for the block Lasso, which is
defined via the block norm. By augmenting a block Lasso estimator $\hat{\beta}$
with the subgradient $S$ of the block norm evaluated at $\hat{\beta}$, we
derive a closed-form density for the joint distribution of $(\hat{\beta},S)$
under a high-dimensional setting. This allows us to draw from an estimated
sampling distribution of $\hat{\beta}$, or more generally any function of
$(\hat{\beta},S)$, by Monte Carlo algorithms. We demonstrate the application of
estimator augmentation in group inference with the group Lasso and a de-biased
group Lasso constructed as a function of $(\hat{\beta},S)$. Our numerical
results show that importance sampling via estimator augmentation can be orders
of magnitude more efficient than parametric bootstrap in estimating tail
probabilities for significance tests. This work also brings new insights into
the geometry of the sample space and the solution uniqueness of the block
Lasso.


title:
Dynamical instability of a driven-dissipative electron-hole condensate
  in the BCS-BEC-crossover region

abstract:
  We present a stability analysis on a driven-dissipative electron-hole
condensate in the BCS (Bardeen-Cooper-Schrieffer)-BEC
(Bose-Einstein-condensation)-crossover region. Extending the combined
BCS-Leggett theory with the generalized random phase approximation (GRPA) to
the non-equilibrium case by employing the Keldysh formalism, we show that the
pumping-and-decay of carriers causes a depairing effect on excitons. This
phenomenon gives rise to an attractive interaction between excitons in the BEC
regime, as well as a supercurrent that anomalously flows anti-parallel to
$\nabla \theta({\bf r})$ (where $\theta({\bf r})$ is the phase of the
condensate) in the BCS regime, both leading to dynamical instabilities of an
exciton-BEC. Our result suggests that substantial region of the exciton-BEC
phase in the phase diagram (in terms of the interaction strength and the decay
rate) is unstable.

categories: cond-mat.str-el cond-mat.mes-hall cond-mat.other cond-mat.quant-gas cond-mat.supr-con


title: Poisson intensity estimation with reproducing kernels

abstract:
  Despite the fundamental nature of the inhomogeneous Poisson process in the
theory and application of stochastic processes, and its attractive
generalizations (e.g. Cox process), few tractable nonparametric modeling
approaches of intensity functions exist, especially when observed points lie in
a high-dimensional space. In this paper we develop a new, computationally
tractable Reproducing Kernel Hilbert Space (RKHS) formulation for the
inhomogeneous Poisson process. We model the square root of the intensity as an
RKHS function. Whereas RKHS models used in supervised learning rely on the
so-called representer theorem, the form of the inhomogeneous Poisson process
likelihood means that the representer theorem does not apply. However, we prove
that the representer theorem does hold in an appropriately transformed RKHS,
guaranteeing that the optimization of the penalized likelihood can be cast as a
tractable finite-dimensional problem. The resulting approach is simple to
implement, and readily scales to high dimensions and large-scale datasets.


title: PCM and APCM Revisited: An Uncertainty Perspective

abstract:
  In this paper, we take a new look at the possibilistic c-means (PCM) and
adaptive PCM (APCM) clustering algorithms from the perspective of uncertainty.
This new perspective offers us insights into the clustering process, and also
provides us greater degree of flexibility. We analyze the clustering behavior
of PCM-based algorithms and introduce parameters $\sigma_v$ and $\alpha$ to
characterize uncertainty of estimated bandwidth and noise level of the dataset
respectively. Then uncertainty (fuzziness) of membership values caused by
uncertainty of the estimated bandwidth parameter is modeled by a conditional
fuzzy set, which is a new formulation of the type-2 fuzzy set. Experiments show
that parameters $\sigma_v$ and $\alpha$ make the clustering process more easy
to control, and main features of PCM and APCM are unified in this new
clustering framework (UPCM). More specifically, UPCM reduces to PCM when we set
a small $\alpha$ or a large $\sigma_v$, and UPCM reduces to APCM when clusters
are confined in their physical clusters and possible cluster elimination are
ensured. Finally we present further researches of this paper.


title: The Planetary Nebulae Luminosity Function (PNLF): current perspectives

abstract:
  This paper starts with a brief historical review about the PNLF and its use
as a distance indicator. Then the PNLF distances are compared with Surface
Brightness Fluctuations (SBF) distances and Tip of the Red Giant Branch (TRGB)
distances. A Monte Carlo method to generate simulated PNLFs is described,
leading to the last subject: recent progress in reproducing the expected
maximum final mass in old stellar populations, a stellar astrophysics enigma
that has been challenging us for quite some time.


title:
Non-trivial role of interlayer cation states in iron-based
  superconductors

abstract:
  Unconventional superconductivity in iron pnictides and chalcogenides has been
suggested to be controlled by the interplay of low-energy antiferromagnetic
spin fluctuations and the particular topology of the Fermi surface in these
materials. Based on this premise, one would also expect the large class of
isostructural and isoelectronic iron germanide compounds to be good
superconductors. As a matter of fact, they, however, superconduct at very low
temperatures or not at all. In this work we establish that superconductivity in
iron germanides is suppressed by strong ferromagnetic tendencies, which
surprisingly do not originate from changes in bond-angles or -distances with
respect to iron pnictides and chalcogenides, but are due to changes in the
electronic structure in a wide range of energies happening upon substitution of
atom species (As by Ge and the corresponding spacer cations). Our results
indicate that superconductivity in iron-based materials may not always be fully
understood based on $d$ or $dp$ model Hamiltonians only.


title:
Estimation of Bandlimited Grayscale Images From the Single Bit
  Observations of Pixels Affected by Additive Gaussian Noise

abstract:
  The estimation of grayscale images using their single-bit zero mean Gaussian
noise-affected pixels is presented in this paper. The images are assumed to be
bandlimited in the Fourier Cosine transform (FCT) domain. The images are
oversampled over their Nyquist rate in the FCT domain. We propose a
non-recursive approach based on first order approximation of Cumulative
Distribution Function (CDF) to estimate the image from single bit pixels which
itself is based on Banach's contraction theorem. The decay rate for mean
squared error of estimating such images is found to be independent of the
precision of the quantizer and it varies as $O(1/N)$ where $N$ is the
"effective" oversampling ratio with respect to the Nyquist rate in the FCT
domain.


title: Regret Bounds for Lifelong Learning

abstract:
  We consider the problem of transfer learning in an online setting. Different
tasks are presented sequentially and processed by a within-task algorithm. We
propose a lifelong learning strategy which refines the underlying data
representation used by the within-task algorithm, thereby transferring
information from one task to the next. We show that when the within-task
algorithm comes with some regret bound, our strategy inherits this good
property. Our bounds are in expectation for a general loss function, and
uniform for a convex loss. We discuss applications to dictionary learning and
finite set of predictors. In the latter case, we improve previous
$O(1/\sqrt{m})$ bounds to $O(1/m)$ where $m$ is the per task sample size.


title: The Promise and Prejudice of Big Data in Intelligence Community

abstract:
  Big data holds critical importance in the current generation of information
technology, with applications ranging from financial, industrial, academic to
defense sectors. With the exponential rise of open source data from social
media and increasing government monitoring, big data is now also linked with
national security, and subsequently to the intelligence community. In this
study I review the scope of big data sciences in the functioning of
intelligence community. The major part of my study focuses on the inherent
limitations of big data, which affects the intelligence agencies from gathering
of information to anticipating surprises. The limiting factors range from
technical to ethical issues connected with big data. My study concludes the
need of experts with domain knowledge from intelligence community to
efficiently guide big data analysis for timely filling the knowledge gaps. As a
case study on limitations of using big data, I narrate some of the ongoing work
in nuclear intelligence using simple analytics and argue on why big data
analysis in that case would lead to unnecessary complications. For further
investigation, I highlight cases of crowdsource forecasting tournaments and
predicting unrest from social media.


title: Two-dimensional Excitonic Photoluminescence in Graphene on Cu surface

abstract:
  Despite having outstanding electrical properties, graphene is unsuitable for
optical devices because of its zero band gap. Here, we report two-dimensional
excitonic photoluminescence (PL) from graphene grown on Cu(111) surface, which
shows an unexpected remarkably sharp and strong emission near 3.16 eV
(full-width at half-maximum $\leq$ 3meV) and multiple emissions around 3.18 eV.
As temperature increases, these emissions blue-shift, showing the
characteristic negative thermal coefficient of graphene. Observed PLs originate
from significantly suppressed dispersion of excited electrons in graphene
caused by hybridization of graphene $\pi$ and Cu d orbitals of the 1st and 2nd
Cu layers at a shifted saddle point 0.525(M+K) of Brillouin zone. This finding
provides a new pathway to engineering novel optoelectronic graphene devices,
whilst maintaining the outstanding electrical properties of graphene.


title: Random matrix analysis for gene interaction networks in cancer cells

abstract:
  Investigations of topological uniqueness of gene interaction networks in
cancer cells are essential for understanding this disease. Based on the random
matrix theory, we study the distribution of the nearest neighbor level spacings
$P(s)$ of interaction matrices for gene networks in human cancer cells. The
interaction matrices are computed using the Cancer Network Galaxy (TCNG)
database, which is a repository of gene interactions inferred by a Bayesian
network model. 256 NCBI GEO entries regarding gene expressions in human cancer
cells have been selected for the Bayesian network calculations in TCNG. We
observe the Wigner distribution of $P(s)$ when the gene networks are dense
networks that have more than $\sim 38,000$ edges. In the opposite case, when
the networks have smaller numbers of edges, the distribution $P(s)$ becomes the
Poisson distribution. We investigate relevance of $P(s)$ both to the size of
the networks and to edge frequencies that manifest reliance of the inferred
gene interactions.


title:
The effect of hydrodynamical simulation inspired dark matter velocity
  profile on directional detection of dark matter

abstract:
  Directional detection is an important way to detect dark matter. An input to
these experiments is the dark matter velocity distribution. Recent
hydrodynamical simulations have shown that the dark matter velocity
distribution differs substantially from the Standard Halo Model. We study the
impact of some of these updated velocity distribution in dark matter
directional detection experiments. We calculate the ratio of events required to
confirm the forward-backward asymmetry and the existence of the ring of maximum
recoil rate using different dark matter velocity distributions for $^{19}$F and
Xe targets. We show that with the use of updated dark matter velocity profiles,
the forward-backward asymmetry and the ring of maximum recoil rate can be
confirmed using a factor of $\sim$2 - 3 less events when compared to that using
the Standard Halo Model.

categories: astro-ph.CO astro-ph.GA hep-ex hep-ph nucl-ex


title:
$U(1)$ Fermi liquid theory - A Fermi liquid state that supports
  exclusion statistics

abstract:
  We propose in this paper an effective low-energy theory for interacting
fermion systems which supports exclusion statistics. The theory can be viewed
as an extension of Landau Fermi liquid theory where besides quasi-particle
energy $\xi_{\mathbf{k}}$, the kinetic momentum $\mathbf{k}$ of quasi-particles
depends also on quasi-particle occupation numbers as a result of momentum
($k$)-dependent current-current interaction. The dependence of kinetic momentum
on quasi-particles excitations leads to change in density of states and
exclusion statistics. The properties of this new Fermi liquid state is studied
where we show that the state (which we call $U(1)$-Fermi liquid state) has
Fermi-liquid like properties except that the quasi-particles are {\em not}
adiabatically connected to bare fermions in the system and the state may not
satisfy Luttinger theorem.


title:
Light-Cone Singularities and Transverse-Momentum-Dependent Factorization
  at Twist-3

abstract:
  We study transverse-momentum-dependent factorization at twist-3 for Drell-Yan
processes. The factorization can be derived straightforwardly at leading order
of $\alpha_s$. But at this order we find that light-cone singularities already
exist and effects of soft gluons are not correctly factorized. We regularize
the singularities with gauge links off the light-cone and introduce a soft
factor to factorize the effects of soft gluons. Interestingly, the soft factor
must be included in the definition of subtracted TMD parton distributions to
correctly factorize the effects of soft gluons. We derive the Collins-Soper
equation for one of twist-3 TMD parton distributions. The equation can be
useful for resummation of large logarithms terms appearing in the corresponding
structure function in collinear factorization. However, the derived equation is
nonhomogeneous. This will make the resummation complicated.


title:
High energy neutrinos produced in the accretion disks by neutrons from
  nuclei disintegrated in the AGN jets

abstract:
  We investigate the consequences of acceleration of nuclei in jets of active
galaxies not far from the surface of an accretion disk. The nuclei can be
accelerated in the re-connection regions in the jet and/or at the jet boundary,
between the relativistic jet and its cocoon. It is shown that the relativistic
nuclei can efficiently fragment onto specific nucleons in collisions with the
disk radiation. Neutrons, directed towards the accretion disk, take a
significant part of energy from the relativistic nuclei. These neutrons develop
a cascade in the dense accretion disk. We calculate the neutrino spectra
produced in such hadronic cascade within the accretion disk. We propose that
the neutrinos produced in such scenario from the whole population of
super-massive black holes in active galaxies can explain the extragalactic
neutrino background recently measured by the IceCube neutrino detector,
provided that $5\%$ fraction of galaxies is AGN and a few percent of neutrons
reach the accretion disk. It is predicted that the neutrino signals in the
present neutrino detectors, produced in terms of such a model, are not expected
to be detectable even from the nearby radio galaxies similar to M87.


title:
{\delta}-phosphorene: a two dimensional material with high negative
  Poisson's ratio

abstract:
  As a basic mechanical parameter, Poisson's ratio ({\nu}) measures the
mechanical responses of solids against external loads. In rare cases, materials
have a negative Poisson's ratio (NPR), and present an interesting auxetic
effect. That is, when a material is stretched in one direction, it will expand
in the perpendicular direction. To design modern nanoscale electromechanical
devices with special functions, two dimensional (2D) auxetic materials are
highly desirable. In this work, based on first principles calculations, we
rediscover the previously proposed {\delta}-phosphorene ({\delta}-P) nanosheets
[Jie Guan et al., Phys. Rev. Lett. 2014, 113, 046804] are good auxetic
materials with a high NPR. The results show that the Young's modulus and
Poisson's ratio of {\delta}-P are all anisotropic. The NPR value along the
grooved direction is up to -0.267, which is much higher than the recently
reported 2D auxetic materials. The auxetic effect of {\delta}-P originated from
its puckered structure is robust and insensitive to the number of layers due to
weak interlayer interactions. Moreover, {\delta}-P possesses good flexibility
because of its relatively small Young's modulus and high critical crack strain.
If {\delta}-P can be synthesized, these extraordinary properties would endow it
great potential in designing low dimensional electromechanical devices.


title:
Statistical Inference for Model Parameters in Stochastic Gradient
  Descent

abstract:
  The stochastic gradient descent (SGD) algorithm has been widely used in
statistical estimation for large-scale data due to its computational and memory
efficiency. While most existing works focus on the convergence of the objective
function or the error of the obtained solution, we investigate the problem of
statistical inference of true model parameters based on SGD when the population
loss function is strongly convex and satisfies certain smoothness conditions.
Our main contributions are two-fold. First, in the fixed dimension setup, we
propose two consistent estimators of the asymptotic covariance of the average
iterate from SGD: (1) a plug-in estimator, and (2) a batch-means estimator,
which is computationally more efficient and only uses the iterates from SGD.
Both proposed estimators allow us to construct asymptotically exact confidence
intervals and hypothesis tests. Second, for high-dimensional linear regression,
using a variant of the SGD algorithm, we construct a debiased estimator of each
regression coefficient that is asymptotically normal. This gives a one-pass
algorithm for computing both the sparse regression coefficients and confidence
intervals, which is computationally attractive and applicable to online data.


title: Path to Low Cost Microfluidics

abstract:
  The paper describes a novel concept for a low cost microfluidic platform
utilizing materials and processes used in low cost thermal inkjet printing. The
concept re-purposes the jetting elements to create pumps, mixers, and valves
all necessary components for the transport of fluids in a broad range of
microfluidic applications.


title:
A Simplified Model for Fast Optimization of Free-Electron Laser
  Oscillator

abstract:
  A simplified theoretical model for free-electron laser oscillator (FELO)
simulation which reserves the main physics is proposed. In stead of using
traditional macro particles sampling method, the theoretical model takes
advantages of low gain theory to calculate the optical power single-pass gain
in the undulator analytically, and some reasonable approximations are made to
simplify the calculation of power growth in the cavity. The theoretical
analysis of single-pass gain, power growth, time-dependent laser profile
evolution and cavity desynchronism are accomplished more efficiently. We
present the results of infrared wavelength FELO and X-ray FELO with the new
model. The results is checked by simulation with GENESIS and OPC which
demonstrates the validity of the theoretical model.


title: Anomaly Detection with the Voronoi Diagram Evolutionary Algorithm

abstract:
  This paper presents the Voronoi diagram-based evolutionary algorithm
(VorEAl). VorEAl partitions input space in abnormal/normal subsets using
Voronoi diagrams. Diagrams are evolved using a multi-objective bio-inspired
approach in order to conjointly optimize classification metrics while also
being able to represent areas of the data space that are not present in the
training dataset. As part of the paper VorEAl is experimentally validated and
contrasted with similar approaches.


title:
Upper critical field in the model with finite range interaction between
  electrons

abstract:
  We develop a theory of the upper critical field in a BCS superconductor with
a nonlocal interaction between electrons. We have shown that the nonlocal
interaction is characterized by the parameter $k_F\rho_0$ where $k_F$ is the
Fermi momentum and $\rho_0$ is the radius of electron-electron interaction. The
presence of the external magnetic field leads to the generation of additional
components of the order parameter with different angular momentum. This effect
leads to the enhancement of the upper critical field above the orbital limiting
field. In addition the upward curvature in the temperature dependence of
$H_{c2}(T)$ in the clean limit is predicted. The impurity scattering suppresses
the effect in the dirty limit.


title: Patterning Superconductivity in a Topological Insulator

abstract:
  While topological superconductors are predicted to provide building blocks
for fault-tolerant quantum computing, one of the remaining challenges is to
find a convenient experimental platform that would allow patterning of
circuits. We find that superconductivity can be patterned directly into
Bi$_2$Se$_3$ nanostructures by selective doping with palladium (Pd).
Superconducting regions are defined by depositing Pd on top of the
nanostructures using electron beam lithography, followed by in-situ annealing.
Electrical transport measurements at low temperatures show either partial or
full superconducting transition, depending on the doping conditions. Structural
characterization techniques indicate that Pd remains localized in the targeted
areas, making it possible to pattern superconducting circuits of arbitrary
shapes in this topological material.


title:
Corrected knife-edge-based reconstruction of tightly focused higher
  order beams

abstract:
  The knife-edge method is an established technique for profiling of even
tightly focused light beams. However the straightforward implementation of this
method fails if the materials and geometry of the knife-edges are not chosen
carefully or in particular if knife-edges are used that are made of pure
materials. In these cases artifacts are introduced in the shape and position of
the reconstructed beam profile due to the interaction of the light beam under
study with the knife. Hence, corrections to the standard knife-edge evaluation
method are required. Here we investigate the knife-edge method for highly
focused radially and azimuthally polarized beams and their linearly polarized
constituents. We introduce relative shifts for those constituents and report on
the consistency with the case of a linearly polarized Gaussian beam. An adapted
knife-edge reconstruction technique is presented and proof-of-concept tests
demonstrating the reconstruction of beam profiles are shown.


title:
Utility Maximization and Indifference Value under Risk and Information
  Constraints for a Market with a Change Point

abstract:
  In this article we consider an optimization problem of expected utility
maximization of continuous-time trading in a financial market. This trading is
constrained by a benchmark for a utility-based shortfall risk measure. The
market consists of one asset whose price process is modeled by a Geometric
Brownian motion where the market parameters change at a random time. The
information flow is modeled by initially and progressively enlarged filtrations
which represent the knowledge about the price process, the Brownian motion and
the random time. We solve the maximization problem and give the optimal
terminal wealth depending on these different filtrations for general utility
functions by using martingale representation results for the corresponding
filtration. Moreover, for a special utility function and risk measure we
calculate the utility indifference value which measures the gain of further
information for the investor.


title:
Three-dimensional anomalous twisted gauge theories with global symmetry:
  Implications for quantum spin liquids

abstract:
  Topological spin liquids can be described by topological gauge theories with
global symmetry. Due to the presence of both nontrivial bulk deconfined gauge
fluxes and global symmetry, topological spin liquids are examples of the
so-called "Symmetry Enriched Topological phases" (SET). In this paper, we find
that, in some twisted versions of topological gauge theories (with discrete
Abelian gauge group $G_g$), implementing a global symmetry (denoted by $G_s$)
is anomalous although symmetry charge carried by topological point-like
excitations is normally fractionalized and classified by the second cohomology
group. To demonstrate the anomaly, we fully gauge the global symmetry,
rendering a new gauge theory that is not gauge invariant. Therefore, the SET
order of the ground state is anomalous, which cannot exist in 3D system alone.
Such anomalous state construction generalizes the "2D surface topological
order" to 3D. A concrete example with $G_g=\mathbb{Z}_2\times\mathbb{Z}_4$ and
$G_s=\mathbb{Z}_2$ is calculated.


title: On the solvability of the Brinkman-Forchheimer-extended Darcy equation

abstract:
  The nonlinear Brinkman-Forchheimer-extended Darcy equation is used to model
some porous medium flow in chemical reactors of packed bed type. The results
concerning the existence and uniqueness of a weak solution are presented for
nonlinear convective flows in medium with nonconstant porosity and for small
data. Furthermore, the finite element approximations to the flow profiles in
the fixed bed reactor are presented for several Reynolds numbers at the
non-Darcy's range.


title:
Spectral-Galerkin Approximation and Optimal Error Estimate for Stokes
  Eigenvalue Problems in Polar Geometries

abstract:
  In this paper we propose and analyze spectral-Galerkin methods for the Stokes
eigenvalue problem based on the stream function formulation in polar
geometries. We first analyze the stream function} formulated fourth-order
equation under the polar coordinates, then we derive the pole condition and
reduce the problem on a circular disk to a sequence of equivalent
one-dimensional eigenvalue problems that can be solved in parallel. The novelty
of our approach lies in the construction} of suitably weighted Sobolev spaces
according to the pole conditions, based on which, the optimal error estimate
for approximated eigenvalue of each one dimensional problem can be obtained.
Further, we extend our method to the non-separable Stokes eigenvalue problem in
an elliptic domain and establish the optimal error bounds. Finally, we provide
some numerical experiments to validate our theoretical results and algorithms.


title: Optimality certificates for convex minimization and Helly numbers

abstract:
  We consider the problem of minimizing a convex function over a subset of R^n
that is not necessarily convex (minimization of a convex function over the
integer points in a polytope is a special case). We define a family of duals
for this problem and show that, under some natural conditions, strong duality
holds for a dual problem in this family that is more restrictive than
previously considered duals.


title: Minkowski Endomorphisms

abstract:
  Several open problems concerning Minkowski endomorphisms and Minkowski
valuations are solved. More precisely, it is proved that all Minkowski
endomorphisms are uniformly continuous but that there exist Minkowski
endomorphisms that are not weakly-monotone. This answers questions posed
repeatedly by various authors. Furthermore, a recent representation result for
Minkowski valuations by Schuster and Wannerer is improved under additional
homogeneity assumptions. Also a question related to the structure of Minkowski
endomorphisms by the same authors is answered. Finally, it is shown that there
exists no McMullen decomposition in the class of continuous, even,
$SO(n)$-equivariant and translation invariant Minkowski valuations extending a
result by Parapatits and Wannerer.


title: Electrostatics of quadrupolarizable media

abstract:
  The classical macroscopic Maxwell equations are approximated. They are a
corollary of the multipole expansion of the local electrostatic potential up to
dipolar terms. But quadrupolarization of the medium should not be neglected if
the molecules which build up the medium possess large quadrupole moment or do
not have any dipole moment. If we include the quadrupolar terms in Maxwell
equations we obtain the quadrupolar analogue of Poisson's equation: $\nabla^2
\phi - L^2_Q\nabla^4 \phi = - \rho / \varepsilon$. This equation is of the
fourth order and it requires not only the two classical boundary conditions but
also two additional ones: continuous electric field and the relation of the
jump of the normal quadrupolarizability at the surface to the intrinsic normal
surface dipole moment. The account of the quadrupole moment of the molecules
leads to significant differences compared to the classical electrostatic
theory.


title: On holomorphic Artin L-functions

abstract:
  Let $K/\mathbb Q$ be a finite Galois extension, $s_0\in \mathbb C\setminus
\{1\}$, ${\it Hol}(s_0)$ the semigroup of Artin L-functions holomorphic at
$s_0$. If the Galois group is almost monomial then Artin's L-functions are
holomorphic at $s_0$ if and only if $ {\it Hol}(s_0)$ is factorial. This holds
also if $s_0$ is a zero of an irreducible L-function of dimension $\leq 2$,
without any condition on the Galois group.


title: Scale-invariant radio jets and varying black hole spin

abstract:
  Compact radio cores associated with relativistic jets are often observed in
both active galactic nuclei and X-ray binaries. Their radiative properties
follow some general scaling laws which primarily depend on their masses and
accretion rates. However, it has been suggested that the black hole spin can
also strongly influence the power and radio flux of these. Here, we attempt to
estimate the dependency of the radio luminosity of steady jets launched by
accretion disks on black hole mass, accretion rate and spin using numerical
simulations. We make use of 3D GRMHD simulations of accretion disks around
low-luminosity black holes in which the jet radio emission is produced by the
jet sheath. We find that the radio flux increases roughly by a factor of 6 as
the back hole spin increases from a~0 to a=0.98. This is comparable to the
increase in accretion power with spin, meaning that the ratio between radio jet
and accretion power is hardly changing. Although our jet spine power scales as
expected for the Blandford-Znajek process, the dependency of jet radio
luminosity on the black hole spin is somewhat weaker. Also weakly rotating
black holes can produce visible radio jets. The overall scaling of the radio
emission with black hole mass and accretion rate is consistent with the
scale-invariant analytical models used to explain the fundamental plane of
black hole activity. Spin does not introduce a significant scatter in this
model. The jet-sheath model can describe well resolved accreting systems, such
as SgrA* and M87, as well as the general scaling behavior of low-luminosity
black holes. Hence the model should be applicable to a wide range of radio jets
in sub-Eddington black holes. The black hole spin has an effect on the
production of visible radio jet, but it may not be the main driver to produce
visible radio jets. An extension of our findings to powerful quasars remains
speculative.


title:
Detection of Very Low-Frequency Quasi-Periodic Oscillations in the 2015
  Outburst of V404 Cygni

abstract:
  In June 2015, the black hole X-ray binary (BHXRB) V404 Cygni went into
outburst for the first time since 1989. Here, we present a comprehensive search
for quasi-periodic oscillations (QPOs) of V404 Cygni during its recent
outburst, utilizing data from six instruments on board five different X-ray
missions: Swift/XRT, Fermi/GBM, Chandra/ACIS, INTEGRAL's IBIS/ISGRI and JEM-X,
and NuSTAR. We report the detection of a QPO at 18 mHz simultaneously with both
Fermi/GBM and Swift/XRT, another example of a rare but slowly growing new class
of mHz-QPOs in BHXRBs linked to sources with a high orbital inclination.
Additionally, we find a duo of QPOs in a Chandra/ACIS observation at 73 mHz and
1.03 Hz, as well as a QPO at 136 mHz in a single Swift/XRT observation that can
be interpreted as standard Type-C QPOs. Aside from the detected QPOs, there is
significant structure in the broadband power, with a strong feature observable
in the Chandra observations between 0.1 and 1 Hz. We discuss our results in the
context of current models for QPO formation.


title:
A Four-Body Convex Central Configuration with Perpendicular Diagonals Is
  Necessarily a Kite

abstract:
  We prove that any four-body convex central configuration with perpendicular
diagonals must be a kite configuration. The result extends to general power-law
potential functions, including the planar four-vortex problem.


title:
Pacific Neutrinos: Towards a High Precision Measurement of CP Violation
  ?

abstract:
  The application of deep sea low energy neutrino detection techniques to long
baseline neutrino physics is investigated, with a focus on a possible
configuration based on a FNAL neutrino beam impinging a detector hosted by the
NEPTUNE/OOI submarine observatories offshore of British Columbia.


title: Coherence depletion in the Grover quantum search algorithm

abstract:
  We investigate the role of quantum coherence depletion (QCD) in Grover search
algorithm (GA) by using several typical measures of quantum coherence and
quantum correlations. By using the relative entropy of coherence measure
($\mathcal{C}_r$), we show that the success probability depends on the QCD. The
same phenomenon is also found by using the $l_1$ norm of coherence measure
($\mathcal{C}_{l_1}$). In the limit case, the cost performance is defined to
characterize the behavior about QCD in enhancing the success probability of GA,
which is only related to the number of searcher items and the scale of
database, no matter using $\mathcal{C}_r$ or $\mathcal{C}_{l_1}$. In
generalized Grover search algorithm (GGA), the QCD for a class of states
increases with the required optimal measurement time. In comparison, the
quantification of other quantum correlations in GA, such as pairwise
entanglement, multipartite entanglement, pairwise discord and genuine
multipartite discord, cannot be directly related to the success probability or
the optimal measurement time. Additionally, we do not detect pairwise
nonlocality or genuine tripartite nonlocality in GA since
Clauser-Horne-Shimony-Holt inequality and Svetlichny's inequality are not
violated.


title: Critical properties of the eight-vertex model in a field

abstract:
  The general eight-vertex model on a square lattice is studied numerically by
using the Corner Transfer Matrix Renormalization Group method. The method is
tested on the symmetric (zero-field) version of the model, the obtained
dependence of critical exponents on model's parameters is in agreement with
Baxter's exact solution and weak universality is verified with a high accuracy.
It was suggested longtime ago that the symmetric eight-vertex model is a
special exceptional case and in the presence of external fields the
eight-vertex model falls into the Ising universality class. We confirm
numerically this conjecture in a subspace of vertex weights, except for two
specific combinations of vertical and horizontal fields for which the system
still exhibits weak universality.


title: Extended Particles and the Exterior Calculus

abstract:
  These notes were delivered as a series of NIMROD lectures at the Rutherford
Appleton Laboratory by the author in February 1976 (RL-76-022). The purpose of
these lectures was primarily two-fold: to discuss the classical theory of free
point particles, free strings and free membranes from a unified viewpoint; and
to present in the process of doing this the rudiments of an intrinsic
geometrical calculus that the author has found of immense value in
investigating these systems. It is shown how the equations of motion for such
classically extended relativistic systems arise in a very simple manner from a
principle of stationary action and furthermore how the boundary conditions for
finite systems may be derived in a gauge invariant way. Momenta are naturally
introduced and the primary constraints that exist in a Hamiltonian description
follow simply. Calculations may proceed in an index-free manner until
components are required. It is at this stage that one can, if one desires,
impose gauge conditions and remove non-independent degrees of freedom. Such
methods can be applied in any spacetime of any dimension and metric, and
examples are given throughout.


title:
A rational use of BCA code MARLOWE for ballistic effects of ion beam
  irradiation in the ion mixing formalism: comparison to Molecular Dynamics

abstract:
  Understanding ballistic effects caused by ion beam irradiation, and linking
them with induced structure can be a key point for controlling and predicting
the microstructure of irradiated materials. For this purpose, we have
investigated ballistic effects from an ion mixing formalism point of view. The
displacement cascades in copper and AgCu alloy were obtained using binary
collision approximation (BCA) and molecular dynamics (MD) simulations. We
employed BCA-based code MARLOWE for its ability to simulate high energy
displacement cascades. A first set of simulations was performed using both
methods on pure copper for energies ranging from 0.5 keV to 20 keV. The results
of BCA and MD simulations are compared, evidencing rationally parametrized
MARLOWE to be predictive. A second set of simulations was then carried out
using BCA only. Following experimental studies, AgCu alloy was subjected to 1
MeV krypton ions. MARLOW simulations are found to be in good agreement with
experimental results.


title:
Spin transfer driven resonant expulsion of a magnetic vortex core for
  efficient rf detector

abstract:
  Spin transfer magnetization dynamics have led to considerable advances in
Spintronics, including opportunities for new nanoscale radiofrequency devices.
Among the new functionalities is the radiofrequency(rf) detection using the
spin diode rectification effect in spin torque nano-oscillators (STNOs). In
this study, we focus on a new phenomenon, the resonant expulsion of a magnetic
vortex in STNOs. This effect is observed when the excitation vortex radius, due
to spin torques associated to rf currents, becomes larger than the actual
radius of the STNO. This vortex expulsion is leading to a sharp variation of
the voltage at the resonant frequency. Here we show that the detected frequency
can be tuned by different parameters; furthermore, a simultaneous detection of
different rf signals can be achieved by real time measurements with several
STNOs having different diameters. This result constitutes a first
proof-of-principle towards the development of a new kind of nanoscale rf
threshold detector.


title:
Adiabatic physics of an exchange-coupled spin-dimer system:
  magnetocaloric effect, zero-point fluctuations, and possible two-dimensional
  universal behavior

abstract:
  We present the magnetic and thermal properties of the bosonic-superfluid
phase in a spin-dimer network using both quasistatic and rapidly-changing
pulsed magnetic fields. The entropy derived from a heat-capacity study reveals
that the pulsed-field measurements are strongly adiabatic in nature and are
responsible for the onset of a significant magnetocaloric effect (MCE). In
contrast to previous predictions we show that the MCE is not just confined to
the critical regions, but occurs for all fields greater than zero at
sufficiently low temperatures. We explain the MCE using a model of the thermal
occupation of exchange-coupled dimer spin-states and highlight that failure to
take this effect into account inevitably leads to incorrect interpretations of
experimental results. In addition, the heat capacity in our material is
suggestive of an extraordinary contribution from zero-point fluctuations and
appears to indicate universal behavior with different critical exponents at the
two field-induced critical points. The data are consistent with a
two-dimensional nature of spin excitations in the system.


title:
Functional limit theorems for the number of busy servers in a
  $G/G/\infty$ queue

abstract:
  We discuss weak convergence of the number of busy servers in a $G/G/\infty$
queue in the $J_1$-topology on the Skorokhod space. We prove two functional
limit theorems, with random and nonrandom centering, respectively, thereby
solving two open problems stated in Mikosch and Resnick (2006}. A new integral
representation for the limit Gaussian process is given.


title:
Regularization parameter selection in indirect regression by residual
  based bootstrap

abstract:
  Residual-based analysis is generally considered a cornerstone of statistical
methodology. For a special case of indirect regression, we investigate the
residual-based empirical distribution function and provide a uniform expansion
of this estimator, which is also shown to be asymptotically most precise. This
investigation naturally leads to a completely data-driven technique for
selecting a regularization parameter used in our indirect regression function
estimator. The resulting methodology is based on a smooth bootstrap of the
model residuals. A simulation study demonstrates the effectiveness of our
approach.


title: A random version of principal component analysis in data clustering

abstract:
  Principal component analysis (PCA) is a widespread technique for data
analysis that relies on the covariance-correlation matrix of the analyzed data.
However to properly work with high-dimensional data, PCA poses severe
mathematical constraints on the minimum number of different replicates or
samples that must be included in the analysis. Here we show that a modified
algorithm works not only on well dimensioned datasets, but also on degenerated
ones.


title:
Direct semi-parametric estimation of the state price density implied in
  option prices

abstract:
  We present a model for direct semi-parametric estimation of the State Price
Density (SPD) implied in quoted option prices. We treat the observed prices as
expected values of possible pay-offs at maturity, weighted by the unknown
probability density function. We model the logarithm of the latter as a smooth
function while matching the expected values of the potential pay-offs with the
observed prices. This leads to a special case of the penalized composite link
model. Our estimates do not rely on any parametric assumption on the underlying
asset price dynamics and are consistent with no-arbitrage conditions. The model
shows excellent performance in simulations and in application to real data.


title:
Performance Assessment of Variational Integrators for Thermomechanical
  Problems

abstract:
  Structure-preserving integrators are in the focus of ongoing research because
of their distinguished features of robustness and long time stability. In
particular, their formulation for coupled problems that include dissipative
mechanisms is still an active topic. Conservative formulations, such as the
thermo-elastic case without heat conduction, fit well into a variational
framework and have been solved with variational integrators, whereas the
inclusions of viscosity and heat transfer are still under investigation. To
encompass viscous forces and heat transfer, an extension of Hamilton's
principle is required. In this contribution we derive variational integrators
for thermo-viscoelastic systems with classical heat transfer. Their results are
compared for two discrete model problems vs. Energy-Entropy-Momentum methods.
Such comparisons allow to draw conclusions about their relative performance,
weaknesses and strengths.


title: Heat flux of a granular gas with homogeneous temperature

abstract:
  A steady state of a granular gas with homogeneous granular temperature, no
mass flow, and nonzero heat flux is studied. The state is created by applying
an external position--dependent force or by enclosing the grains inside a
curved two--dimensional silo. At a macroscopic level, the state is identified
with one solution to the inelastic Navier--Stokes equations, due to the
coupling between the heat flux induced by the density gradient and the external
force. On the contrary, at the mesoscopic level, by exactly solving a BGK model
or the inelastic Boltzmann equation in an approximate way, a one--parametric
family of solutions is found. Molecular dynamics simulations of the system in
the quasi--elastic limit are in agreement with the theoretical results.