title:
On Stochastic Geometry Modeling of Cellular Uplink Transmission with
  Truncated Channel Inversion Power Control

abstract:
  Using stochastic geometry, we develop a tractable uplink modeling paradigm
for outage probability and spectral efficiency in both single and multi-tier
cellular wireless networks. The analysis accounts for per user equipment (UE)
power control as well as the maximum power limitations for UEs. More
specifically, for interference mitigation and robust uplink communication, each
UE is required to control its transmit power such that the average received
signal power at its serving base station (BS) is equal to a certain threshold
$\rho_o$. Due to the limited transmit power, the UEs employ a truncated channel
inversion power control policy with a cutoff threshold of $\rho_o$. We show
that there exists a transfer point in the uplink system performance that
depends on the tuple: BS intensity ($\lambda$), maximum transmit power of UEs
($P_u$), and $\rho_o$. That is, when $P_u$ is a tight operational constraint
with respect to [w.r.t.] $\lambda$ and $\rho_o$, the uplink outage probability
and spectral efficiency highly depend on the values of $\lambda$ and $\rho_o$.
In this case, there exists an optimal cutoff threshold $\rho^*_o$, which
depends on the system parameters, that minimizes the outage probability. On the
other hand, when $P_u$ is not a binding operational constraint w.r.t. $\lambda$
and $\rho_o$, the uplink outage probability and spectral efficiency become
independent of $\lambda$ and $\rho_o$. We obtain approximate yet accurate
simple expressions for outage probability and spectral efficiency which reduce
to closed-forms in some special cases.


title: On the structure of $S_2$-ifications of complete local rings

abstract:
  Motivated by work of Hochster and Huneke, we investigate several
constructions related to the $S_2$-ification $T$ of a complete equidimensional
local ring $R$: the canonical module, the top local cohomology module,
topological spaces of the form $\operatorname{Spec}(R)-V(J)$, and the (finite
simple) graph $\Gamma_R$ with vertex set $\operatorname{Min}(R)$ defined by
Hochster and Huneke. We generalize one of their results by showing, e.g., that
the number of maximal ideals of $T$ is equal to the number of connected
components of $\Gamma_R$. We further investigate this graph by exhibiting a
technique for showing that a given graph $G$ can be realized as one of the form
$\Gamma_R$.


title:
Physical Constraints on a Class of Two-Higgs Doublet Models with FCNC at
  tree level

abstract:
  We analyse the constraints and some of the phenomenological implications of a
class of two Higgs doublet models where there are flavour-changing neutral
currents (FCNC) at tree level but the potentially dangerous FCNC couplings are
suppressed by small entries of the CKM matrix $V$. This class of models have
the remarkable feature that, as a result of a discrete symmetry of the
Lagrangian, the FCNC couplings are entirely fixed in the quark sector by $V$
and the ratio $v_2 /v_1$ of the vevs of the neutral Higgs. The discrete
symmetry is extended to the leptonic sector, so that there are FCNC in the
leptonic sector with their flavour structure fixed by the leptonic mixing
matrix. We analyse a large number of processes, including decays mediated by
charged Higgs at tree level, processes involving FCNC at tree level, as well as
loop induced processes. We show that in this class of models one has new
physical scalars beyond the standard Higgs boson, with masses reachable at the
next round of experiments.


title: Constraining the role of novae as progenitors of Type Ia Supernovae

abstract:
  (Abridged) White dwarfs (WDs) undergoing unstable nuclear burning on their
surfaces, resulting in the nova phenomenon, have been considered as one of the
prospective candidates for the still elusive progenitors of SNeIa. We propose
that statistics of novae in nearby galaxies may be a powerful tool to gauge the
role of such systems in producing SNeIa. Using multicycle nova evolutionary
models, we compute the number and temporal distribution of novae that would be
produced by a typical (unstably burning) SNIa progenitor before reaching the
Chandrasekhar mass limit (M_ch) and exploding. Combined with the observed nova
rates, this can be used to constrain the maximal contribution of the nova
channel to the SNIa rate in nearby galaxies. The M31 nova rate measured by the
POINT-AGAPE survey is 65/yr. Assuming that all these novae will reach M_ch, we
obtain the maximal SNIa rate novae may produce to be (1-5)x10^-4/yr. This
constrains the overall contribution of the nova channel to the SNIa rate in M31
at <2-7%. Furthermore, ~80% of novae generated by a successful SNIa progenitor
have short decay times (t2<10 days), and are produced when the WD mass is close
to M_ch. We point out that statistics of such fast novae can provide a
sensitive diagnostic of the contribution of the nova channel to the final
stages of mass accumulation by the single degenerate (SD) SNIa progenitors. To
explore the prospects of their use, we investigate the efficiency of detecting
fast novae in an M31 nova survey of the PTF class. We find that a survey with
limiting magnitude of m_R~22 observing at least every 2nd night will catch ~90%
of fast novae expected in the SD scenario. Such surveys should be detecting
fast novae in M31 at a rate of the order of >10^3xf per yr, where f is the
fraction of SNeIa which accreted in the unstable nuclear burning regime while
accumulating the final ~0.1M_sun before the SNIa explosion.


title: Bridgeland Stability of Line Bundles on Surfaces

abstract:
  We study the Bridgeland stability of line bundles on surfaces using
Bridgeland stability conditions determined by divisors. We show that given a
smooth projective surface $S$, a line bundle $L$ is always Bridgeland stable
for those stability conditions if there are no curves $C\subseteq S$ of
negative self-intersection. When a curve $C$ of negative self-intersection is
present, $L$ is destabilized by $L(-C)$ for some stability conditions. We
conjecture that line bundles of the form $L(-C)$ are the only objects that can
destabilize $L$, and that torsion sheaves of the form $L(C)|_C$ are the only
objects that can destabilize $L[1]$. We prove our conjecture in several cases,
and in particular for Hirzebruch surfaces.


title: On the generation of Heronian triangles

abstract:
  We describe several algorithms for the generation of integer Heronian
triangles with diameter at most $n$. Two of them have running time
$\mathcal{O}\left(n^{2+\varepsilon}\right)$. We enumerate all integer Heronian
triangles for $n\le 600000$ and apply the complete list on some related
problems.


title: Representation theory and cohomology of Khovanov-Lauda-Rouquier algebras

abstract:
  This expository paper is based on the lectures given at the program `Modular
Representation Theory of Finite and $p$-adic Groups' at the National University
of Singapore. We are concerned with recent results on representation theory and
cohomology of KLR algebras, with emphasis on standard module theory.


title:
The contamination of the surface of Vesta by impacts and the delivery of
  the dark material

abstract:
  The Dawn spacecraft observed the presence of dark material, which in turn
proved to be associated with OH and H-rich material, on the surface of Vesta.
The source of this dark material has been identified with the low albedo
asteroids, but it is still a matter of debate whether the delivery of the dark
material is associated with a few large impact events, to micrometeorites or to
the continuous, secular flux of impactors on Vesta. The continuous flux
scenario predicts that a significant fraction of the exogenous material
accreted by Vesta should be due to non-dark impactors likely analogous to
ordinary chondrites, which instead represent only a minor contaminant in the
HED meteorites. We explored the continuous flux scenario and its implications
for the composition of the vestan regolith, taking advantage of the data from
the Dawn mission and the HED meteorites. We used our model to show that the
stochastic events scenario and the micrometeoritic flux scenario are natural
consequences of the continuous flux scenario. We then used the model to
estimate the amounts of dark and hydroxylate materials delivered on Vesta since
the LHB and we showed how our results match well with the values estimated by
the Dawn mission. We used our model to assess the amount of Fe and siderophile
elements that the continuous flux of impactors would mix in the vestan
regolith: concerning the siderophile elements, we focused our attention on the
role of Ni. The results are in agreement with the data available on the Fe and
Ni content of the HED meteorites and can be used as a reference frame in future
studies of the data from the Dawn mission and of the HED meteorites. Our model
cannot yet provide an answer to the fate of the missing non-carbonaceous
contaminants, but we discuss possible reasons for this discrepancy.


title: Inversely Prepolarized Piezoceramic Cantilever

abstract:
  A nonuniform piezoelectric cantilever with enhanced amplitude of vibration at
resonances is proposed. The cantilever made of lead zirconate titanate (type of
PZT-5H) containing inversely poled piezoelectric domains shows an advantageous
increase in vibration amplitude when compared to a single domain device. The
amplitude of vibrations is enhanced when the domain boundaries are located at
the nodes of vibration displacement. The vibration amplitude of a cantilever
with 2 or 3 periodically inverted domains is mostly affected at the 2nd or 3rd
resonance frequency, respectively. The amplitudes are calculated using the
Finite Element method (FEM).


title: Constraints on muon-specific dark forces

abstract:
  The recent measurement of the Lamb shift in muonic hydrogen allows for the
most precise extraction of the charge radius of the proton which is currently
in conflict with other determinations based on $e-p$ scattering and hydrogen
spectroscopy. This discrepancy could be the result of some new muon-specific
force with O(1-100) MeV force carrier---in this paper we concentrate on vector
mediators. Such an explanation faces challenges from the constraints imposed by
the $g-2$ of the muon and electron as well as precision spectroscopy of muonic
atoms. In this work we complement the family of constraints by calculating the
contribution of hypothetical forces to the muonium hyperfine structure. We also
compute the two-loop contribution to the electron parity violating amplitude
due to a muon loop, which is sensitive to the muon axial-vector coupling.
Overall, we find that the combination of low-energy constraints favors the mass
of the mediator to be below 10 MeV, and that a certain degree of tuning is
required between vector and axial-vector couplings of new vector particles to
muons in order to satisfy constraints from muon $g-2$. However, we also observe
that in the absence of a consistent standard model embedding, high energy
weak-charged processes accompanied by the emission of new vector particles are
strongly enhanced by $(E/m_V)^2$, with $E$ a characteristic energy scale and
$m_V$ the mass of the mediator. In particular, leptonic $W$ decays impose the
strongest constraints on such models completely disfavoring the remainder of
the parameter space.


title: Heat Kernel on Smooth Metric Measure Spaces with Nonnegative Curvature

abstract:
  We derive a local Gaussian upper bound for the $f$-heat kernel on complete
smooth metric measure space $(M,g,e^{-f}dv)$ with nonnegative Bakry-\'{E}mery
Ricci curvature, which generalizes the classic Li-Yau estimate. As
applications, we obtain a sharp $L_f^1$-Liouville theorem for $f$-subharmonic
functions and an $L_f^1$-uniqueness property for nonnegative solutions of the
$f$-heat equation, assuming $f$ is of at most quadratic growth. In particular,
any $L_f^1$-integrable $f$-subharmonic function on gradient shrinking or steady
Ricci solitons must be constant. We also provide explicit $f$-heat kernel for
Gaussian solitons.


title: Ess\'en Lectures: Representation Theory of Symmetric Groups

abstract:
  These are partial lecture notes from the fifteen Ess\'en Lectures for
graduate students at Uppsala University given (in four days!) in June 2013.


title: Exploiting citation networks for large-scale author name disambiguation

abstract:
  We present a novel algorithm and validation method for disambiguating author
names in very large bibliographic data sets and apply it to the full Web of
Science (WoS) citation index. Our algorithm relies only upon the author and
citation graphs available for the whole period covered by the WoS. A pair-wise
publication similarity metric, which is based on common co-authors,
self-citations, shared references and citations, is established to perform a
two-step agglomerative clustering that first connects individual papers and
then merges similar clusters. This parameterized model is optimized using an
h-index based recall measure, favoring the correct assignment of well-cited
publications, and a name-initials-based precision using WoS metadata and
cross-referenced Google Scholar profiles. Despite the use of limited metadata,
we reach a recall of 87% and a precision of 88% with a preference for
researchers with high h-index values. 47 million articles of WoS can be
disambiguated on a single machine in less than a day. We develop an h-index
distribution model, confirming that the prediction is in excellent agreement
with the empirical data, and yielding insight into the utility of the h-index
in real academic ranking scenarios.


title: Electronic chemical potentials of porous metal-organic frameworks

abstract:
  The binding energy of an electron in a material is a fundamental
characteristic, which determines a wealth of important chemical and physical
properties. For metal-organic frameworks this quantity is hitherto unknown. We
present a general approach for determining the vacuum level of porous
metal-organic frameworks and apply it to obtain the first ionisation energy for
six prototype materials including zeolitic, covalent and ionic frameworks. This
approach for valence band alignment can explain observations relating to the
electrochemical, optical and electrical properties of porous frameworks.


title: Spacetime approach to force-free magnetospheres

abstract:
  Force-Free Electrodynamics (FFE) describes magnetically dominated
relativistic plasma via non-linear equations for the electromagnetic field
alone. Such plasma is thought to play a key role in the physics of pulsars and
active black holes. Despite its simple covariant formulation, FFE has primarily
been studied in 3+1 frameworks, where spacetime is split into space and time.
In this article we systematically develop the theory of force-free
magnetospheres taking a spacetime perspective. Using a suite of spacetime tools
and techniques (notably exterior calculus) we cover 1) the basics of the
theory, 2) exact solutions that demonstrate the extraction and transport of the
rotational energy of a compact object (in the case of a black hole, the
Blandford-Znajek mechanism), 3) the behavior of current sheets, 4) the general
theory of stationary, axisymmetric magnetospheres and 5) general properties of
pulsar and black hole magnetospheres. We thereby synthesize, clarify and
generalize known aspects of the physics of force-free magnetospheres, while
also introducing several new results.


title: Ribbon graphs and bialgebra of Lagrangian subspaces

abstract:
  To each ribbon graph we assign a so-called L-space, which is a Lagrangian
subspace in an even-dimensional vector space with the standard symplectic form.
This invariant generalizes the notion of the intersection matrix of a chord
diagram. Moreover, the actions of Morse perestroikas (or taking a partial dual)
and Vassiliev moves on ribbon graphs are reinterpreted nicely in the language
of L-spaces, becoming changes of bases in this vector space. Finally, we define
a bialgebra structure on the span of L-spaces, which is analogous to the
4-bialgebra structure on chord diagrams.


title: Nonlinear eigenvalue problems

abstract:
  This paper presents a detailed asymptotic study of the nonlinear differential
equation y'(x)=\cos[\pi xy(x)] subject to the initial condition y(0)=a.
Although the differential equation is nonlinear, the solutions to this
initial-value problem bear a striking resemblance to solutions to the
time-independent Schroedinger eigenvalue problem. As x increases from x=0, y(x)
oscillates and thus resembles a quantum wave function in a classically allowed
region. At a critical value x=x_{crit}, where x_{crit} depends on a, the
solution y(x) undergoes a transition; the oscillations abruptly cease and y(x)
decays to 0 monotonically as x-->\infty. This transition resembles the
transition in a wave function that occurs at a turning point as one enters the
classically forbidden region. Furthermore, the initial condition a falls into
discrete classes; in the nth class of initial conditions a_{n-1}<a<a_n
(n=1,2,3,...), y(x) exhibits exactly n maxima in the oscillatory region. The
boundaries a_n of these classes are the analogs of quantum-mechanical
eigenvalues. An asymptotic calculation of $a_n$ for large $n$ is analogous to a
high-energy semiclassical (WKB) calculation of eigenvalues in quantum
mechanics. The principal result of this paper is that as n-->\infty,
a_n~A\sqrt{n}, where A=2^{5/6}. Numerical analysis reveals that the first
Painleve transcendent has an eigenvalue structure that is quite similar to that
of the equation y'(x)=\cos[\pi xy(x)] and that the nth eigenvalue grows with n
like a constant times n^{3/5} as n-->\infty. Finally, it is noted that the
constant A is numerically very close to the lower bound on the power-series
constant P in the theory of complex variables, which is associated with the
asymptotic behavior of zeros of partial sums of Taylor series.


title:
Worldsheet instantons and coupling selection rules in heterotic
  orbifolds

abstract:
  We review recent results on string coupling selection rules for heterotic
orbifolds, derived using conformal field theory. Such rules are the first step
towards understanding the viability of the recently obtained compactifications
with potentially realistic particle spectra. They arise from the properties of
the worldsheet instantons that mediate the couplings, and include stringy
effects that would seem 'miraculous' to an effective field theory observer.


title: The effects of a fast-turning trajectory in multiple-field inflation

abstract:
  The latest results from PLANCK impose strong constraints on features in the
spectrum of the curvature perturbations from inflation. We analyse the
possibility of particle production induced by sharp turns of the trajectory in
field space in inflation models with multiple fields. Although the evolution of
the background fields can be altered by particle production, we find rather
modest changes in the power spectrum even for the most extreme case in which
the entire kinetic energy of the scalar fields is converted into particles.


title: Quantization of Lie bialgebras revisited

abstract:
  We describe a new method of quantization of Lie bialgebras, based on a
construction of Hopf algebras out of a cocommutative coalgebra and a braided
comonoidal functor.


title: The Uniqueness of Signature Problem in the Non-Markov Setting

abstract:
  The goal of this paper is to simplify and strengthen the Le Jan-Qian
approximation scheme of studying the uniqueness of signature problem to the
non-Markov setting. We establish a general framework for a class of
multidimensional stochastic processes over [0,1] under which with probability
one, the signature (the collection of iterated path integrals in the sense of
rough paths) is well-defined and determines the sample paths of the process up
to reparametrization. In particular, by using the Malliavin calculus we show
that our method applies to a class of Gaussian processes including fractional
Brownian motion with Hurst parameter H>1/4, the Ornstein-Uhlenbeck process and
the Brownian bridge.


title: First observations of the Phoebe ring in optical light

abstract:
  The Phoebe ring, Saturn's largest and faintest ring, lies far beyond the
planet's well-known main rings. It is primarily sourced by collisions with
Saturn's largest irregular satellite Phoebe, perhaps through stochastic
macroscopic collisions, or through more steady micrometeoroid bombardment. The
ring was discovered with the Spitzer Space Telescope at 24 $\mu$m and has a
normal optical depth of $\sim 2 \times 10^{-8}$ (Verbiscer et al. 2009). We
report the first observations of sunlight scattered off the Phoebe ring using
the Cassini spacecraft's ISS camera at optical wavelengths. We find that
material between $\approx 130-210$ Saturnian radii ($R_S$) from the planet
produces an I/F of $1.7 \pm 0.1 \times 10^{-11}$ per $R_S$ of the line-of-sight
distance through the disk. Combining our measurements with the Spitzer infrared
data, we can place constraints on the ring-particles' light-scattering
properties. Depending on the particles' assumed phase function, the derived
single-scattering albedo can match either photometric models of Phoebe's dark
regolith or brighter sub-surface material excavated by macroscopic impacts on
Phoebe.


title: Monopoles and Wilson Lines

abstract:
  We present a semi-classical description of BPS monopoles interacting with
Wilson lines. The Wilson lines are represented as non-Abelian spin impurities.
These spins interact with the monopole degrees of freedom through a natural
connection on the moduli space. We employ this technology in N = 2 SU(2) gauge
theory to count the number of framed BPS states of a single monopole bound to
Wilson lines in different representations.


title: Oscillon Lifetime in the Presence of Quantum Fluctuations

abstract:
  We consider the stability of oscillons in 2+1 space-time dimensions, in the
presence of quantum fluctuations. Taking the oscillon to be the inhomogeneous
mean field of a self-interacting quantum scalar field, we compare its classical
evolution to the evolution in the presence of quantum fluctuations. The
evolution of these and their back reaction onto the mean field is implemented
through the inhomogeneous Hartree approximation, in turn computed as a
statistical ensemble of field realizations. We find that although the lifetime
of the oscillon is dramatically reduced compared to the classical limit, the
regions of longevity are similar in the space of Gaussian initial
configurations.


title: Parsimonious Topic Models with Salient Word Discovery

abstract:
  We propose a parsimonious topic model for text corpora. In related models
such as Latent Dirichlet Allocation (LDA), all words are modeled
topic-specifically, even though many words occur with similar frequencies
across different topics. Our modeling determines salient words for each topic,
which have topic-specific probabilities, with the rest explained by a universal
shared model. Further, in LDA all topics are in principle present in every
document. By contrast our model gives sparse topic representation, determining
the (small) subset of relevant topics for each document. We derive a Bayesian
Information Criterion (BIC), balancing model complexity and goodness of fit.
Here, interestingly, we identify an effective sample size and corresponding
penalty specific to each parameter type in our model. We minimize BIC to
jointly determine our entire model -- the topic-specific words,
document-specific topics, all model parameter values, {\it and} the total
number of topics -- in a wholly unsupervised fashion. Results on three text
corpora and an image dataset show that our model achieves higher test set
likelihood and better agreement with ground-truth class labels, compared to LDA
and to a model designed to incorporate sparsity.


title:
Fools gold? Developer dilemmas in a closed mobile application market
  platform

abstract:
  In this paper, we outline some potential conflicts that platform owners and
software developers face in mobile application markets. Our arguments are based
on comments captured in specialized online discussion forums, in which
developers gather to share knowledge and experiences. The key findings indicate
conflicts of interests, including 1) intra-platform competition, 2)
discriminative promotion, 3) entry prevention, 4) restricted monetization, 5)
restricted knowledge sharing, 6) substitution, and 7) strategic technology
selection. Opportunistic platform owners may use their power to discriminate
between third-part software developers. However, there are also potential
strategic solutions that developers can apply; for example diversification
(multi-homing), syndication and brand building.


title: Star Formation and Substructure in Galaxy Clusters

abstract:
  We investigate the relationship between star formation (SF) and substructure
in a sample of 107 nearby galaxy clusters using data from the Sloan Digital Sky
Survey (SDSS). Several past studies of individual galaxy clusters have
suggested that cluster mergers enhance cluster SF, while others find no such
relationship. The SF fraction in multi-component clusters (0.228 +/- 0.007) is
higher than that in single-component clusters (0.175 +/- 0.016) for galaxies
with M^0.1_r < -20.5. In both single- and multi-component clusters, the
fraction of star-forming galaxies increases with clustercentric distance and
decreases with local galaxy number density, and multi-component clusters show a
higher SF fraction than single-component clusters at almost all clustercentric
distances and local densities. Comparing the SF fraction in individual clusters
to several statistical measures of substructure, we find weak, but in most
cases significant at greater than 2 sigma, correlations between substructure
and SF fraction. These results could indicate that cluster mergers may cause
weak but significant SF enhancement in clusters, or unrelaxed clusters exhibit
slightly stronger SF due to their less evolved states relative to relaxed
clusters.


title: Reversible first-order transition in Pauli percolation

abstract:
  Percolation plays an important role in fields and phenomena as diverse as the
study of social networks, the dynamics of epidemics, the robustness of
electricity grids, conduction in disordered media, and geometric properties in
statistical physics. We analyse a new percolation problem in which the first
order nature of an equilibrium percolation transition can be established
analytically and verified numerically. The rules for this site percolation
model are physical and very simple, requiring only the introduction of a weight
$W(n)=n+1$ for a cluster of size $n$. This establishes that a discontinuous
percolation transition can occur with qualitatively more local interactions
than in all currently considered examples of explosive percolation; and that,
unlike these, it can be reversible. This greatly extends both the applicability
of such percolation models in principle, and their reach in practice.


title:
Stochastic accretion of planetesimals onto white dwarfs: constraints on
  the mass distribution of accreted material from atmospheric pollution

abstract:
  This paper explores how the stochastic accretion of planetesimals onto white
dwarfs would be manifested in observations of their atmospheric pollution.
Archival observations of pollution levels for unbiased samples of DA and non-DA
white dwarfs are used to derive the distribution of accretion rates, confirming
that rates become systematically lower as sinking time is decreased, with no
discernable dependence on cooling age. The accretion rates expected from
planetesimals that are all the same mass (ie, a mono-mass distribution) are
explored both analytically and using a Monte Carlo model, quantifying how
measured accretion rates inevitably depend on sinking time, since different
sinking times probe different times since the last accretion event. However,
that dependence is so dramatic that a mono-mass distribution can be excluded.
Consideration of accretion from a broad distribution of planetesimal masses
uncovers an important conceptual difference: accretion is continuous (rather
than stochastic) for planetesimals below a certain mass, and the accretion of
such planetesimals determines the rate typically inferred from observations;
smaller planetesimals dominate the rates for shorter sinking times. A
reasonable fit to the observationally inferred accretion rate distributions is
found with model parameters consistent with a collisionally evolved mass
distribution up to Pluto-mass, and an underlying accretion rate distribution
consistent with that expected from descendants of debris discs of main sequence
A stars. With these parameters, while both DA and non-DA white dwarfs accrete
from the same broad planetesimal distribution, this model predicts that the
pollution seen in DAs is dominated by the continuous accretion of <35km
objects, and that in non-DAs by >35km objects (though the dominant size varies
between stars by around an order of magnitude from this value)...


title: Persistence of locality in systems with power-law interactions

abstract:
  Motivated by recent experiments with ultra-cold matter, we derive a new bound
on the propagation of information in $D$-dimensional lattice models exhibiting
$1/r^{\alpha}$ interactions with $\alpha>D$. The bound contains two terms: One
accounts for the short-ranged part of the interactions, giving rise to a
bounded velocity and reflecting the persistence of locality out to intermediate
distances, while the other contributes a power-law decay at longer distances.
We demonstrate that these two contributions not only bound but, except at long
times, \emph{qualitatively reproduce} the short- and long-distance dynamical
behavior following a local quench in an $XY$ chain and a transverse-field Ising
chain. In addition to describing dynamics in numerous intractable long-range
interacting lattice models, our results can be experimentally verified in a
variety of ultracold-atomic and solid-state systems.


title: The discovery of a radio halo in PLCK G147.3-16.6 at z=0.65

abstract:
  Recent X-ray and Sunyaev-Zel'dovich (SZ) observations have dramatically
increased the number of known distant galaxy clusters. In some merging,
low-redshift (z<0.4) clusters, centrally-located, diffuse, extended radio
emission (called radio halos) has been found. Using the Giant Metrewave Radio
Telescope (GMRT), we report the detection of diffuse radio emission in the
binary-merging cluster PLCK G147.3-16.6 located at z = 0.65. We classify the
emission as a giant radio halo due to the large physical extent of about 0.9
Mpc and low-surface brightness. We measure an integrated flux density of
$7.3\pm1.1$ mJy at 610 MHz for the radio halo, resulting in a 1.4 GHz radio
power of $5.1 \times 10^{24}$ W/Hz. The radio halo power is consistent with
that expected from the known correlation between X-ray luminosity or the
cluster integrated SZ signal and radio power. Our observations also suggest
that more of these distant radio halos could be discovered with the GMRT.


title: Young AGN outburst running over older X-ray cavities

abstract:
  Although the energetic feedback from active galactic nuclei (AGN) is believed
to have a profound effect on the evolution of galaxies and clusters of
galaxies, details of the AGN heating remain elusive. Here, we study NGC 193 - a
nearby lenticular galaxy - based on X-ray (Chandra) and radio (VLA and GMRT)
observations. These data reveal the complex AGN outburst history of the galaxy:
we detect a pair of inner X-ray cavities, an outer X-ray cavity, a shock front,
and radio lobes extending beyond the inner cavities. We suggest that the inner
cavities were produced ~78 Myr ago by a weaker AGN outburst, while the outer
cavity, the radio lobes, and the shock front are due to a younger (13-26 Myr)
and (4-8) times more powerful outburst. Combining this with the observed
morphology of NGC 193, we conclude that NGC 193 likely represents the first
example of a second, more powerful, AGN outburst overrunning an older, weaker
outburst. These results help to understand how the outburst energy is
dissipated uniformly in the core of galaxies, and therefore may play a crucial
role in resolving how AGN outbursts suppress the formation of large cooling
flows at cluster centers.


title:
Effect of a spin-active interface on proximity-induced superconductivity
  in topological insulators

abstract:
  We examine the effect of a spin-active interface on the symmetry of
proximity-induced superconducting pairing amplitudes in topological insulators.
We develop a model to investigate the leading order contribution to the pairing
amplitude considering 3 different kinds of spin-active interfaces: 1) those
that induce spin-dependent scattering phases, 2) those that flip the spin of
incident electrons, and 3) interfaces that both induce spin-dependent phases
and flip the spins of incident electrons. We find that in cases (1) and (3)
odd-frequency triplet pairing is induced in the TI while for case (2) no
odd-frequency pairing is induced to leading order. We compare our results to
those for normal metals and ferromagnetic materials finding that the nontrivial
spin structure of the TI leads to qualitatively different behavior.


title:
Charge transport in two dimensions limited by strong short-range
  scatterers: Going beyond parabolic dispersion and Born approximation

abstract:
  We investigate the conductivity of charge carriers confined to a
two-dimensional system with the non-parabolic dispersion $k^N$ with $N$ being
an arbitrary natural number. A delta-shaped scattering potential is assumed as
the major source of disorder. We employ the exact solution of the
Lippmann-Schwinger equation to derive an analytical Boltzmann conductivity
formula valid for an arbitrary scattering potential strength. The range of
applicability of our analytical results is assessed by a numerical study based
on the finite size Kubo formula. We find that for any $N>1$, the conductivity
demonstrates a linear dependence on the carrier concentration in the limit of a
strong scattering potential strength. This finding agrees with the conductivity
measurements performed recently on chirally stacked multilayer graphene where
the lowest two bands are non-parabolic and the adsorbed hydrocarbons might act
as strong short-range scatterers.


title:
Harmonics in the Dark-Matter Sky: Directional Detection in the
  Fourier-Bessel Basis

abstract:
  Details about the velocity distribution of weakly interacting massive
particle (WIMP) dark matter in our galaxy may be revealed by nuclear-recoil
detectors with directional sensitivity. Previous studies have assumed that the
velocity distribution takes a simple functional form characterized by a small
number of parameters. More recent work has shown that basis-function expansions
may allow for more general parameterization; such an approach has been
considered for both the one-dimensional speed and momentum distributions, and
also for three-dimensional velocity distributions obeying certain equilibrium
conditions. In this work, I extend this basis-function approach to allow for
arbitrary velocity distributions by working in the Fourier-Bessel basis,
deriving an analytic expression for the directional recoil spectrum. Such an
approach is completely general, and may be useful if the velocity distribution
is too complex to be characterized by simple functional forms or is not
completely virialized. Results concerning the three-dimensional Radon transform
of the Fourier-Bessel basis functions may be of general interest for
tomographic applications.


title: Effects of the initial conditions on cosmological $N$-body simulations

abstract:
  Cosmology is entering an era of percent level precision due to current large
observational surveys. This precision in observation is now demanding more
accuracy from numerical methods and cosmological simulations. In this paper, we
study the accuracy of $N$-body numerical simulations and their dependence on
changes in the initial conditions and in the simulation algorithms. For this
purpose, we use a series of cosmological $N$-body simulations with varying
initial conditions. We test the influence of the initial conditions, namely the
pre-initial configuration (preIC), the order of the Lagrangian perturbation
theory (LPT), and the initial redshift, on the statistics associated with the
large scale structures of the universe such as the halo mass function, the
density power spectrum, and the maximal extent of the large scale structures.
We find that glass or grid pre-initial conditions give similar results at
$z\lesssim 2$. However, the initial excess of power in the glass initial
conditions yields a subtle difference in the power spectra and the mass
function at high redshifts. The LPT order used to generate the ICs of the
simulations is found to play a crucial role. First-order LPT (1LPT) simulations
underestimate the number of massive haloes with respect to second-order (2LPT)
ones, typically by 2% at $10^{14} h^{-1} M_\odot$ for an initial redshift of
23, and the small-scale power with an underestimation of 6% near the Nyquist
frequency for $z_\mathrm{ini} = 23$. Moreover, at higher redshifts, the
high-mass end of the mass function is significantly underestimated in 1LPT
simulations. On the other hand, when the LPT order is fixed, the starting
redshift has a systematic impact on the low-mass end of the halo mass function.


title: Constraining Exoplanet Mass from Transmission Spectroscopy

abstract:
  Determination of an exoplanet's mass is a key to understanding its basic
properties, including its potential for supporting life. To date, mass
constraints for exoplanets are predominantly based on radial velocity (RV)
measurements, which are not suited for planets with low masses, large
semi-major axes, or those orbiting faint or active stars. Here, we present a
method to extract an exoplanet's mass solely from its transmission spectrum. We
find good agreement between the mass retrieved for the hot Jupiter HD189733b
from transmission spectroscopy with that from RV measurements. Our method will
be able to retrieve the masses of Earth-sized and super-Earth planets using
data from future space telescopes that were initially designed for atmospheric
characterization.


title:
Non-local (but also non-singular) physics at the last stages of
  gravitational collapse

abstract:
  We study the end stages of gravitational collapse of the thin shell of matter
in ingoing Eddington-Finkelstein coordinates. We use the functional Schrodinger
formalism to capture quantum effects in the near singularity limit. We find
that that the equations of motion which govern the behavior of the collapsing
shell near the classical singularity become strongly non-local. This reinforces
previous arguments that quantum gravity in the strong field regime might be
non-local. We managed to solve the non-local equation of motion for the dust
shell case, and found an explicit form of the wavefunction describing the
collapsing shell. This wavefunction and the corresponding probability density
are non-singular at the origin, thus indicating that quantization should be
able to rid gravity of singularities, just as it was the case with the singular
Coulomb potential.


title: Nonlinear stability of laboratory quasi-Keplerian flows

abstract:
  Experiments in a modified Taylor-Couette device, spanning Reynolds numbers of
$10^5$ to greater than $10^6$, reveal the nonlinear stability of
astrophysically-relevant flows. Nearly ideal rotation, expected in the absence
of axial boundaries, is achieved for a narrow range of operating parameters.
Departures from the optimal control space identify centrifugal instability of
boundary layers as the primary source of turbulence likely observed in former
experiments. By driving turbulence from a series of jets we demonstrate the
robustly quiescent nature of quasi-Keplerian flows, indicating that sustained
turbulence does not exist.


title:
Molecular Dynamics in the Multicanonical Ensemble: Equivalence of
  Wang-Landau Sampling, Statistical Temperature Molecular Dynamics, and
  Metadynamics

abstract:
  We show direct formal relationship between the Wang-Landau iteration [PRL 86,
2050 (2001)], metadynamics [PNAS 99, 12562 (2002)] and statistical temperature
molecular dynamics [PRL 97, 050601 (2006)], the major Monte Carlo and molecular
dynamics work-horses for sampling from a generalized, multicanonical ensemble.
We demonstrate that statistical temperature molecular dynamics (which is
formally derived from the Wang-Landau method), augmented by the introduction of
kernel updates of the statistical temperature, generates dynamics which are
indistinguishable from a corresponding metadynamics simulation. We also show
that the use of a Gaussian kernel significantly improves the performance of
statistical temperature molecular dynamics, highlighting the practical benefits
of this improved formal understanding.

categories: cond-mat.stat-mech cond-mat.mtrl-sci cond-mat.soft physics.comp-ph


title: Strong thermal leptogenesis and the absolute neutrino mass scale

abstract:
  We show that successful strong thermal leptogenesis, where the final
asymmetry is independent of the initial conditions and in particular a large
pre-existing asymmetry is efficiently washed-out, favours values of the
lightest neutrino mass $m_1 \gtrsim 10\,{\rm meV}$ for normal ordering (NO) and
$m_1 \gtrsim 3\,{\rm meV}$ for inverted ordering (IO) for models with
orthogonal matrix entries respecting $|\Omega_{ij}^2| \lesssim 2$. . We show
analytically why lower values of $m_1$ require a high level of fine tuning in
the seesaw formula and/or in the flavoured decay parameters (in the electronic
for NO, in the muonic for IO). We also show how this constraint exists thanks
to the measured values of the neutrino mixing angles and can be tighten by a
future determination of the Dirac phase. Our analysis also allows to place more
stringent constraint for a specific model or class of models, such as
$SO(10)$-inspired models, and shows that some models cannot realise strong
thermal leptogenesis for any value of $m_1$. A scatter plot analysis fully
supports the analytical results. We also briefly discuss the interplay with
absolute neutrino mass scale experiments concluding that they will be able in
the coming years to either corner strong thermal leptogenesis or find positive
signals pointing to a non-vanishing $m_1$. Since the constraint is much
stronger for NO than for IO, it is very important that new data from planned
neutrino oscillation experiments will be able to solve the ambiguity.


title:
Ammonia observations in the LBV nebula G79.29+0.46. Discovery of a cold
  ring and some warm spots

abstract:
  The surroundings of Luminous Blue Variable (LBV) stars are excellent
laboratories to study the effects of their high UV radiation, powerful winds,
and strong ejection events onto the surrounding gas and dust. The LBV
G79.29+0.46 powered two concentric infrared rings which may interact with the
infrared dark cloud (IRDC) G79.3+0.3. The Effelsberg 100m telescope was used to
observe the NH_3 (1,1), (2,2) emission surrounding G79.29+0.46 and the IRDC. In
addition, we observed particular positions in the (3,3) transition toward the
strongest region of the IRDC. We report here the first coherent shell-like
structure of dense NH_3 gas associated with an evolved massive star. The shell,
two or three orders of magnitude more tenuous than the IRDC, is well traced in
both ammonia lines, and surrounds the ionized nebula. The NH_3 emission in the
IRDC is characterized by a low and uniform rotational temperature (T_rot ~ 10
K) and moderately high opacities in the (1,1) line. The rest of the observed
field is spotted by warm or hot zones (T_rot > 30 K) and characterized by
optically thin emission of the (1,1) line. The NH_3 abundances are about
10^{-8} in the IRDC, and 10^{-10}-10^{-9} elsewhere. The warm temperatures and
low abundances of NH_3 in the shell suggest that the gas is being heated and
photo-dissociated by the intense UV field of the LBV star. An outstanding
region is found to the south-west (SW) of the LBV star within the IRDC. The
NH_3 (3,3) emission at the centre of the SW region reveals two velocity
components tracing gas at temperatures > 30K. The northern edge of the SW
region agrees with the border of the ring nebula and a region of continuum
enhancement; here, the opacity of the (1,1) line and the NH_3 abundance do not
decrease as expected in a typical clump of an isolated cold dark cloud. This
strongly suggests some kind of interaction between the ring nebula and the
IRDC.


title: On Gaussian Random Supergravity

abstract:
  We study the distribution of metastable vacua and the likelihood of slow roll
inflation in high dimensional random landscapes. We consider two examples of
landscapes: a Gaussian random potential and an effective supergravity potential
defined via a Gaussian random superpotential and a trivial K\"ahler potential.
To examine these landscapes we introduce a random matrix model that describes
the correlations between various derivatives and we propose an efficient
algorithm that allows for a numerical study of high dimensional random fields.
Using these novel tools, we find that the vast majority of metastable critical
points in $N$ dimensional random supergravities are either approximately
supersymmetric with $|F|\ll M_{\text{susy}}$ or supersymmetric. Such
approximately supersymmetric points are dynamical attractors in the landscape
and the probability that a randomly chosen critical point is metastable scales
as $\log(P)\propto -N$. We argue that random supergravities lead to potentially
interesting inflationary dynamics.


title: On the local convergence of the Douglas-Rachford algorithm

abstract:
  We discuss the Douglas-Rachford algorithm to solve the feasibility problem
for two closed sets $A,B$ in $\mathbb{R}^d$. We prove its local convergence to
a fixed point when $A,B$ are finite unions of convex sets. We also show that
for more general nonconvex sets the scheme may fail to converge and start to
cycle, and may then even fail to solve the feasibility problem.


title: Affine extractors over large fields with exponential error

abstract:
  We describe a construction of explicit affine extractors over large finite
fields with exponentially small error and linear output length. Our
construction relies on a deep theorem of Deligne giving tight estimates for
exponential sums over smooth varieties in high dimensions.


title: Probabilistic Signal Shaping for Bit-Metric Decoding

abstract:
  A scheme is proposed that combines probabilistic signal shaping with
bit-metric decoding. The transmitter generates symbols according to a
distribution on the channel input alphabet. The symbols are labeled by bit
strings. At the receiver, the channel output is decoded with respect to a
bit-metric. An achievable rate is derived using random coding arguments. For
the 8-ASK AWGN channel, numerical results show that at a spectral efficiency of
2 bits/s/Hz, the new scheme outperforms bit-interleaved coded modulation (BICM)
without shaping and BICM with bit shaping (i Fabregas and Martinez, 2010) by
0.87 dB and 0.15 dB, respectively, and is within 0.0094 dB of the coded
modulation capacity. The new scheme is implemented by combining a distribution
matcher with a systematic binary low-density parity-check code. The measured
finite-length gains are very close to the gains predicted by the asymptotic
theory.


title:
The suppression of electron correlations in the collapsed tetragonal
  phase of CaFe2As2 under ambient pressure demonstrated by 75As NMR-NQR
  measurements

abstract:
  The static and the dynamic spin correlations in the low temperature collapsed
tetragonal and the high temperature tetragonal phase in CaFe2As2 have been
investigated by 75As nuclear magnetic resonance (NMR) and nuclear quadrupole
resonance (NQR) measurements.
  Through the temperature (T) dependence of the nuclear spin lattice relaxation
rates (1/T1) and the Knight shifts, although stripe-type antiferromagnetic
(AFM) spin correlations are realized in the high temperature tetragonal phase,
no trace of the AFM spin correlations can be found in the non-superconducting,
low temperature, collapsed tetragonal (cT) phase.
  Given that there is no magnetic broadening in 75As NMR spectra, together with
the T-independent behavior of magnetic susceptibility (x) and the T dependence
of 1/T1Tx, we conclude that Fe spin correlations are completely quenched
statically and dynamically in the non-superconducting cT phase in CaFe2As2.


title:
The nonlinear stability of rotationally symmetric spaces with low
  regularity

abstract:
  We consider rotationally symmetric spaces with low regularity, which we
regard as integral currents spaces or manifolds with Sobolev regularity and are
assumed to have nonnegative scalar curvature. Relying on the flat distance and
on Sobolev norms, we establish several nonlinear stability estimates about the
``distance'' between a rotationally symmetric manifold and the Euclidian space,
which are stated in terms of the ADM mass of the manifold. Importantly, we make
explicit the dependencies and scales involved in this problem, particularly the
ADM mass, the depth, and the CMC reference hypersurface. Several notions of
independent interest are introduced in the course of our analysis, including
the notion of depth of a manifold and a scaled version of the flat-distance,
the D-flat distance as we call it, which involves the diameter of the manifold.
Finally we prove a compactness theorem for sequences of regions with uniformly
bounded depth, whose outer boundaries have fixed area and an upper bound on
Hawking mass.


title:
Reversible dynamics of single quantum emitters near metal-dielectric
  interfaces

abstract:
  Here we present a systematic study of the dynamics of a single quantum
emitter near a flat metal-dielectric interface. We identify the key elements
that determine the onset of reversibility in these systems by using a formalism
suited for absorbing media and through an exact integration of the dynamics.
Moreover, when the quantum emitter separation from the surface is small, we are
able to describe the dynamics within a pseudomode description that yields
analytical understanding and allows more powerful calculations.


title: Plasmonic Brownian ratchet

abstract:
  Here we present a Brownian ratchet based on plasmonic interactions. By
periodically turning on and off a laser beam that illuminates a periodic array
of plasmonic nanostructures with broken spatial symmetry, the random thermal
motion of a subwavelength dielectric bead is rectified into one direction. By
means of the Molecular Dynamics technique we show a statistical directed drift
in particle flow.


title:
On the dark matter profile in Sculptor: Breaking the $\beta$ degeneracy
  with Virial shape parameters

abstract:
  We present a new method for studying tracers in gravitational systems where
higher moments of the line-of-sight velocity distribution are introduced via
Virial equations rather than the Jeans equations. Unlike the fourth order Jeans
equations, the fourth order Virial equations can simply be added to the
standard second order Jeans equation without introducing a new anisotropy
parameter $\beta^{\prime}$. We introduce two new global shape parameters
$\zeta_A$ and $\zeta_B$ which replace the kurtosis as a more statistically
robust measure of the shape of the line of sight velocity distribution. We show
that in the case of stars in dwarf spheroidal galaxies these new parameters can
significantly reduce the range of density profiles that are otherwise
consistent with the observed stellar kinematics (a problem sometimes known as
the $\beta$ degeneracy). Specifically, we find that $\zeta_A$ focuses tightly
on a subset of solutions where cusped density profiles are degenerate with more
concentrated cored dark matter halos. If the number density of stars $\nu(r)$
is fixed, then introducing $\zeta_B$ can further reduce the space of solutions
by constraining the outer slope of the dark matter density profile. Assuming a
Plummer profile for $\nu(r)$ we recover the surprising result that the dark
matter in Sculptor may be cuspy after all, in contrast to the conclusions of
other approaches.


title:
Spatially regularized reconstruction of fibre orientation distributions
  in the presence of isotropic diffusion

abstract:
  The connectivity and structural integrity of the white matter of the brain is
nowadays known to be implicated into a wide range of brain-related disorders.
However, it was not before the advent of diffusion Magnetic Resonance Imaging
(dMRI) that researches have been able to examine the properties of white matter
in vivo. Presently, among a range of various methods of dMRI, high angular
resolution diffusion imaging (HARDI) is known to excel in its ability to
provide reliable information about the local orientations of neural fasciculi
(aka fibre tracts). Moreover, as opposed to the more traditional diffusion
tensor imaging (DTI), HARDI is capable of distinguishing the orientations of
multiple fibres passing through a given spatial voxel. Unfortunately, the
ability of HARDI to discriminate between neural fibres that cross each other at
acute angles is always limited, which is the main reason behind the development
of numerous post-processing tools, aiming at the improvement of the directional
resolution of HARDI. Among such tools is spherical deconvolution (SD). Due to
its ill-posed nature, however, SD standardly relies on a number of a priori
assumptions which are to render its results unique and stable. In this paper,
we propose a different approach to the problem of SD in HARDI, which accounts
for the spatial continuity of neural fibres as well as the presence of
isotropic diffusion. Subsequently, we demonstrate how the proposed solution can
be used to successfully overcome the effect of partial voluming, while
preserving the spatial coherency of cerebral diffusion at moderate-to-severe
noise levels. In a series of both in silico and in vivo experiments, the
performance of the proposed method is compared with that of several available
alternatives, with the comparative results clearly supporting the viability and
usefulness of our approach.


title:
Comment on 'Uniqueness of the Equation for Quantum State Vector
  Collapse' [arXiv:1303.4284]

abstract:
  A diffusive stochastic Schr\"odinger equation (SSE) is shown for the first
time, such that contributes to a non-completely positive dynamics. This
contradicts to a recent Letter [arXiv:1303.4284] claiming that SSEs, under most
general conditions, enforce complete-positivity. The general form and
parametrization of the SSE in the Letter is different from an alternative
simpler result, the difference is shown to be completely redundant because of
the gauge-freedom of the state vector's phase.


title:
On a Class of Stochastic Differential Equations With Jumps and Its
  Properties

abstract:
  We study stochastic differential equations with jumps with no diffusion part.
We provide some basic stochastic characterizations of solutions of the
corresponding non-local partial differential equations and prove the Harnack
inequality for a class of these operators. We also establish key connections
between the recurrence properties of these jump processes and the non-local
partial differential operator. One of the key results is the regularity of
solutions of the Dirichlet problem for a class of operators with locally weakly
H\"older continuous kernels.


title: Weak Polarized Electron Scattering

abstract:
  Scattering polarized electrons provides an important probe of the weak
interactions. Precisely measuring the parity-violating left-right cross section
asymmetry is the goal of a number of experiments recently completed or in
progress. The experiments are challenging, since A_{LR} is small, typically
between 10^(-4) and 10^(-8). By carefully choosing appropriate targets and
kinematics, various pieces of the weak Lagrangian can be isolated, providing a
search for physics beyond the Standard Model. For other choices, unique
features of the strong interaction are studied, including the radius of the
neutron density in heavy nuclei, charge symmetry violation, and higher twist
terms. This article reviews the theory behind the experiments, as well as the
general techniques used in the experimental program.


title: Three Series for the Generalized Golden Mean

abstract:
  As is well-known, the ratio of adjacent Fibonacci numbers tends to phi = (1 +
sqrt(5))/2, and the ratio of adjacent Tribonacci numbers (where each term is
the sum of the three preceding numbers) tends to the real root eta of X^3 - X^2
- X - 1 = 0. Letting alpha(n) denote the corresponding ratio for the
generalized Fibonacci numbers, where each term is the sum of the n preceding,
we obtain rapidly converging series for alpha(n), 1/alpha(n), and
1/(2-alpha(n)).


title: z~1 Lya Emitters I. The Luminosity Function

abstract:
  We construct a flux-limited sample of 135 candidate z~1 Lya emitters (LAEs)
from Galaxy Evolution Explorer (GALEX) grism data using a new data cube search
method. These LAEs have luminosities comparable to those at high redshifts and
lie within a 7 Gyr gap present in existing LAE samples. We use archival and
newly obtained optical spectra to verify the UV redshifts of these LAEs. We use
the combination of the GALEX UV spectra, optical spectra, and X-ray imaging
data to estimate the active galactic nucleus (AGN) fraction and its dependence
on Lya luminosity. We remove the AGNs and compute the luminosity function (LF)
from 60 z~1 LAE galaxies. We find that the best fit LF implies a luminosity
density increase by a factor of ~1.5 from z~0.3 to z~1 and ~20 from z~1 to z~2.
We find a z~1 volumetric Lya escape fraction of 0.7+/-0.4%.


title: P\'olya theory for species with an equivariant group action

abstract:
  Joyal's theory of combiantorial species provides a rich and elegant framework
for enumerating combinatorial structures by translating structural information
into algebraic functional equations. We present some classical and folklore
results which interpret the species-theoretic cycle index series in terms of
the P\'{o}lya theory of the action of the symmetric group on the label set,
allowing the enumeration of "partially-labeled" structures and providing an
alternate foundation for several proofs. We also extend the theory to
incorporate information about "structural" group actions (i.e. those which
commute with the label permutation action) on combinatorial species, using the
$\Gamma$-species of Henderson, and present P\'{o}lya-theoretic interpretations
of the associated formal power series. We define the appropriate operations
$+$, $\cdot$, $\circ$, and $\square$ on $\Gamma$-species, give formulas for the
associated operations on $\Gamma$-cycle indices, and illustrate the use of this
theory to study several important examples of combinatorial structures.
Finally, we demonstrate the use of the Sage computer algebra system to
enumerate $\Gamma$-species and their quotients.


title: Subgroup conjugacy separability for surface groups

abstract:
  A group $G$ is called subgroup conjugacy separable (abbreviated as SCS), if
any two finitely generated and non-conjugate subgroups of $G$ remain
non-conjugate in some finite quotient of $G$. We prove that free groups and the
fundamental groups of orientable closed compact surfaces are SCS.


title:
Sign-changing solutions to elliptic second order equations: glueing a
  peak to a degenerate critical manifold

abstract:
  We construct blowing-up sign-changing solutions to some nonlinear critical
equations by glueing a standard bubble to a degenerate function. We develop a
method based on analyticity to perform the glueing when the critical manifold
of solutions is degenerate and no Bianchi--Egnell type condition holds.


title: X-ray mapping the outer regions of galaxy clusters at z= 0.23 and 0.45

abstract:
  The thermal, chemical, and kinematic properties of the potentially
multi-phase circum/inter-galactic medium at the virial radii of galaxy clusters
remain largely uncertain. We present an X-ray study of Abell 2246 and GMBCG
J255.34805+64.23661 (z=0.23 and 0.45), two foreground clusters of the UV-bright
QSO HS 1700+6416, based on 240 ks Chandra/ACIS-I observations. We detect
enhanced diffuse X-ray emission to the projected distances beyond r_{200} radii
of these two clusters. The large-scale X-ray emission is consistent with being
azimuthally symmetric at the projected radii of the QSO (0.36 and 0.8 times the
radii of the two clusters). Assuming a spherical symmetry, we obtain the
de-projected temperature and density profiles of the X-ray-emitting gas.
Excluding the cool cores that are detected, we find that the mean temperature
of the hot gas is about 4.0 keV for Abell 2246 and 5.5 keV for GMBCG
J255.34805+64.23661, although there are indications for temperature drop at
large radii. From these results, we can estimate the density and pressure
distributions of the hot gas along the QSO sightline. We further infer the
radial entropy profile of Abell 2246 and compare it with the one expected from
purely gravitational hierarchical structure formation. This comparison shows
that the ICM in the outer region of the clusters is likely in a clumpy and
multi-phased state. These results, together with the upcoming HST/COS
observations of the QSO sightline, will enable a comprehensive investigation of
the multi-phase medium associated with the clusters.


title: Upper bounds on the k-forcing number of a graph

abstract:
  Given a simple undirected graph $G$ and a positive integer $k$, the
$k$-forcing number of $G$, denoted $F_k(G)$, is the minimum number of vertices
that need to be initially colored so that all vertices eventually become
colored during the discrete dynamical process described by the following rule.
Starting from an initial set of colored vertices and stopping when all vertices
are colored: if a colored vertex has at most $k$ non-colored neighbors, then
each of its non-colored neighbors becomes colored. When $k=1$, this is
equivalent to the zero forcing number, usually denoted with $Z(G)$, a recently
introduced invariant that gives an upper bound on the maximum nullity of a
graph. In this paper, we give several upper bounds on the $k$-forcing number.
Notable among these, we show that if $G$ is a graph with order $n \ge 2$ and
maximum degree $\Delta \ge k$, then $F_k(G) \le \frac{(\Delta-k+1)n}{\Delta - k
+ 1 +\min{\{\delta,k\}}}$. This simplifies to, for the zero forcing number case
of $k=1$, $Z(G)=F_1(G) \le \frac{\Delta n}{\Delta+1}$. Moreover, when $\Delta
\ge 2$ and the graph is $k$-connected, we prove that $F_k(G) \leq
\frac{(\Delta-2)n+2}{\Delta+k-2}$, which is an improvement when $k\leq 2$, and
specializes to, for the zero forcing number case, $Z(G)= F_1(G) \le
\frac{(\Delta -2)n+2}{\Delta -1}$. These results resolve a problem posed by
Meyer about regular bipartite circulant graphs. Finally, we present a
relationship between the $k$-forcing number and the connected $k$-domination
number. As a corollary, we find that the sum of the zero forcing number and
connected domination number is at most the order for connected graphs.


title:
Synaptotagmin 7 Functions as a Ca2+-sensor for Synaptic Vesicle
  Replenishment

abstract:
  Synaptotagmin (syt) 7 is one of three syt isoforms found in all metazoans; it
is ubiquitously expressed, yet its function in neurons remains obscure. Here,
we resolved Ca2+-dependent and Ca2+-independent synaptic vesicle (SV)
replenishment pathways, and found that syt 7 plays a selective and critical
role in the Ca2+-dependent pathway. Mutations that disrupt Ca2+-binding to syt
7 abolish this function, suggesting that syt 7 functions as a Ca2+-sensor for
replenishment. The Ca2+-binding protein calmodulin (CaM) has also been
implicated in SV replenishment, and we found that loss of syt 7 was phenocopied
by a CaM antagonist. Moreover, we discovered that syt 7 binds to CaM in a
highly specific and Ca2+-dependent manner; this interaction requires intact
Ca2+-binding sites within syt 7. Together, these data indicate that a complex
of two conserved Ca2+-binding proteins, syt 7 and CaM, serve as a key regulator
of SV replenishment in presynaptic nerve terminals.


title:
Saturated-absorption spectroscopy revisited: atomic transitions in
  strong magnetic fields ($>$20 mT) with a micrometer-thin cell

abstract:
  The existence of cross-over resonances makes saturated-absorption spectra
very complicated when external magnetic field B is applied. It is demonstrated
for the first time that the use of micrometric-thin cells (MTC,
$L\approx40\,\mu$m) allows application of SA for quantitative studies of
frequency splittings and shifts of the Rb atomic transitions in a wide range of
external magnetic fields, from 0.2 up to 6 kG (20-600 mT). We compare the SA
spectra obtained with the MTC with those obtained with other techniques, and
present applications for optical magnetometry with micrometer spatial
resolution and a broadly tunable optical frequency reference.


title: Supernovae and the Galactic Ecosystem

abstract:
  Supernovae are the dominant source of stellar feedback, which plays an
important role in regulating galaxy formation and evolution. While this
feedback process is still quite uncertain, it is probably not due to individual
supernova remnants as commonly observed. Most supernovae likely take place in
low-density, hot gaseous environments, such as superbubbles and galactic
bulges, and typically produce no long-lasting bright remnants. I review recent
observational and theoretical work on the impact of such supernovae on galaxy
ecosystems, particularly on hot gas in superbubbles and galactic spheroids.


title:
A Semi Distributed Approach for Min-Max Fair Car-Parking Slot Assignment
  Problem

abstract:
  Designing efficient car parking mechanisms that can be potentially integrated
into future intelligent transportation systems is of crucial importance.
Usually, the related design problems are combinatorial and the worst-case
complexity of optimal solution approaches grows exponentially with the problem
sizes. Therefore, such optimal approaches are not scalable and practically
undesirable. As a result, almost all existing methods for parking slot
assignment are simple and greedy approaches, where each car is assigned a free
parking slot, which is closer to its destination. Moreover, no emphasis is
placed to optimize the social benefit of the users during the parking slot
assignment. In this paper, the fairness as a metric for modeling the aggregate
social benefit of the users is considered and a distributed algorithm based on
Lagrange duality theory is developed. The proposed algorithm is gracefully
scalable compared to the optimal methods. In addition, it is shown that the
proposed car parking mechanism preserves privacy in the sense that any car
involved in the algorithm will not be able to discover the destination of any
other car during the algorithm iterations. Numerical results illustrate the
performance of the proposed algorithm compared to the optimal assignment and a
greedy method. They show that our algorithm yields a good tradeoff between the
implementation-level simplicity and the performance. Even though the main
emphasis in this paper resides in the car parking slot assignment problem, our
formulation and the algorithms, in general, can also be applied or adopted in
fair agent-target assignment problems in other application domains.


title: On linear dependence over complete differential algebraic varieties

abstract:
  We extend Kolchin's results on linear dependence over projective varieties in
the constants, to linear dependence over arbitrary complete differential
varieties. We show that in this more general setting, the notion of linear
dependence still has necessary and sufficient conditions given by the vanishing
of a certain system of differential polynomials equations. We also discuss some
conjectural questions around completeness and the catenary problem.


title: Indirect Detection Analysis: Wino Dark Matter Case Study

abstract:
  We perform a multichannel analysis of the indirect signals for the Wino Dark
Matter, including one-loop electroweak and Sommerfeld enhancement corrections.
We derive limits from cosmic ray antiprotons and positrons, from continuum
galactic and extragalactic diffuse gamma-ray spectra, from the absence of
gamma-ray line features at the galactic center above 500 GeV in energy, from
gamma-rays toward nearby dwarf spheroidal galaxies and galaxy clusters, and
from CMB power-spectra. Additionally, we show the future prospects for neutrino
observations toward the inner Galaxy and from antideuteron searches. For each
of these indirect detection probes we include and discuss the relevance of the
most important astrophysical uncertainties that can impact the strength of the
derived limits. We find that the Wino as a dark matter candidate is excluded in
the mass range bellow ~800 GeV from antiprotons and between 1.8 and 3.5 TeV
from the absence of a gamma-ray line feature toward the galactic center. Limits
from other indirect detection probes confirm the main bulk of the excluded mass
ranges.

categories: astro-ph.HE astro-ph.CO astro-ph.GA hep-ph


title:
Sharp Weyl Law for Signed Counting Function of Positive Interior
  Transmission Eigenvalues

abstract:
  We consider the interior transmission eigenvalue (ITE) problem, which arises
when scattering by inhomogeneous media is studied. The ITE problem is not
self-adjoint. We show that positive ITEs are observable together with plus or
minus signs that are defined by the direction of motion of the corresponding
eigenvalues of the scattering matrix (when the latter approach {\bf$z=1$)}. We
obtain a Weyl type formula for the counting function of positive ITEs, which
are taken together with ascribed signs.


title: Almost every vector valued modular form is an oldform

abstract:
  In this article we show that 'most' of the vector valued modular forms w.r.t.
the Weil representation on the groups rings $\mathbb{C}[D]$ of discriminant
forms D are oldforms. The precise meaning of oldform is that the form can be
represented as a sum of lifts of vector valued modular forms on group rings of
quotients $H^\bot/H$ for isotropic subgroups H of D. In this context, 'most'
means that all forms are oldforms if there is a part $\mathbb{Z}/p^e
\mathbb{Z}$ inside a p-part of D that is repeated several times (i.e. >=
4,5,7,9 depending on p and e). We will proceed by giving an oldform detection
mechanism. This criterion also gives rise to an efficient algorithm for
computing the decomposition of cusp forms into their spaces of old- and
newforms when only given the Fourier coefficients of a basis of the space of
cusp forms.


title:
Detuned Mechanical Parametric Amplification as a Quantum Non-Demolition
  Measurement

abstract:
  Recently it has been demonstrated that the combination of weak-continuous
position detection with detuned parametric driving can lead to significant
steady-state mechanical squeezing, far beyond the 3 dB limit normally
associated with parametric driving. In this work, we show the close connection
between this detuned scheme and quantum non-demolition (QND) measurement of a
single mechanical quadrature. In particular, we show that applying an
experimentally realistic detuned parametric drive to a cavity optomechanical
system allows one to effectively realize a QND measurement despite being in the
bad-cavity limit. In the limit of strong squeezing, we show that this scheme
offers significant advantages over standard backaction evasion, not only by
allowing operation in the weak measurement and low efficiency regimes, but also
in terms of the purity of the mechanical state.


title:
A multiplicity bound for graded rings and a criterion for the
  Cohen-Macaulay property

abstract:
  Let $R$ be a polynomial ring over a field. We prove an upper bound for the
multiplicity of $R/I$ when $I$ is a homogeneous ideal of the form $I=J+(F)$,
where $J$ is a Cohen-Macaulay ideal and $F\notin J$. The bound is given in
terms of two invariants of $R/J$ and the degree of $F$. We show that ideals
achieving this upper bound have high depth, and provide a purely numerical
criterion for the Cohen-Macaulay property. Applications to quasi-Gorenstein
rings and almost complete intersections are given.


title:
A posteriori analysis of low-pass spatial filters for approximate
  deconvolution large eddy simulations of homogeneous incompressible flows

abstract:
  The goal of this paper is twofold: first, it investigates the effect of
low-pass spatial filters for approximate deconvolution large eddy simulation
(AD-LES) of turbulent incompressible flows. Second, it proposes the
hyper-differential filter as a means of increasing the accuracy of the AD-LES
model without increasing the computational cost. Box filters, Pad\'{e} filters,
and differential filters with a wide range of parameters are studied in the
AD-LES framework. The AD-LES model, in conjunction with these spatial filters,
is tested in the numerical simulation of the three-dimensional Taylor-Green
vortex problem. The numerical results are benchmarked against direct numerical
simulation (DNS) data. An under-resolved numerical simulation is also used for
comparison purposes. Four criteria are used to investigate the AD-LES model
equipped with these spatial filters: (i) the time series of the volume-averaged
enstrophy; (ii) the volume-averaged third-order structure function; (iii) the
$L^2$-norm of the velocity and vorticity errors; and (iv) the volume-averaged
velocity and vorticity correlation coefficients. According to these criteria,
the numerical results yield the following two conclusions: first, the AD-LES
model equipped with any of these spatial filters yields accurate results at a
fraction of the computational cost of DNS. Second, the most accurate results
are obtained with the hyper-differential filter, followed by the differential
filter. We demonstrate that the results highly depend on the selection of the
filtering procedure. Although a careful parameter choice makes each class of
filters used in this study competitive, it seems that filters whose transfer
function resembles that of the Fourier cut-off filter (such as the
hyper-differential filters) tend to perform best.


title:
A stabilized proper orthogonal decomposition reduced-order model for
  large scale quasigeostrophic ocean circulation

abstract:
  In this paper, a stabilized proper orthogonal decomposition (POD)
reduced-order model (ROM) is presented for the barotropic vorticity equation.
We apply the POD-ROM model to mid-latitude simplified oceanic basins, which are
standard prototypes of more realistic large-scale ocean dynamics. A mode
dependent eddy viscosity closure scheme is used to model the effects of the
discarded POD modes. A sensitivity analysis with respect to the free eddy
viscosity stabilization parameter is performed for various POD-ROMs with
different numbers of POD modes. The POD-ROM results are validated against the
Munk layer resolving direct numerical simulations using a fully conservative
fourth-order Arakawa scheme. A comparison with the standard Galerkin POD-ROM
without any stabilization is also included in our investigation. Significant
improvements in the accuracy over the standard Galerkin model are shown for a
four-gyre ocean circulation problem. This first step in the numerical
assessment of the POD-ROM shows that it could represent a computationally
efficient tool for large scale oceanic simulations over long time intervals.


title:
Coding Schemes with Rate-Limited Feedback that Improve over the
  Nofeedback Capacity for a Large Class of Broadcast Channels

abstract:
  We propose two coding schemes for the two-receiver discrete memoryless
broadcast channel (BC) with rate-limited feedback from one or both receivers.
They improve over the nofeedback capacity region for a large class of channels,
including the class of \emph{strictly essentially less-noisy BCs} that we
introduce in this article. Examples of strictly essentially less-noisy BCs are
the binary symmetric BC (BSBC) or the binary erasure BC (BEBC) with unequal
cross-over or erasure probabilities at the two receivers. When the feedback
rates are sufficiently large, our schemes recover all previously known capacity
results for discrete memoryless BCs with feedback.
  In both our schemes, we let the receivers feed back quantization messages
about their receive signals. In the first scheme, the transmitter simply
\emph{relays} the quantization information obtained from Receiver 1 to Receiver
2, and vice versa. This provides each receiver with a second observation of the
input signal and can thus improve its decoding performance unless the BC is
physically degraded. Moreover, each receiver uses its knowledge of the
quantization message describing its own outputs so as to attain the same
performance as if this message had not been transmitted at all.
  In our second scheme the transmitter first \emph{reconstructs and processes}
the quantized output signals, and then sends the outcome as a common update
information to both receivers. A special case of our second scheme applies also
to memoryless BCs without feedback but with strictly-causal state-information
at the transmitter and causal state-information at the receivers. It recovers
all previous achievable regions also for this setup with state-information.


title: Maximally persistent connections for the periodic type

abstract:
  This paper considers the optimal control problem of connecting two periodic
trajectories with maximal persistence. A maximally persistent trajectory is
close to the periodic type in the sense that the norm of the image of this
trajectory under the operator defining the periodic type is minimal among all
trajectories. A solution is obtained in this paper for the case when the two
trajectories have the same period but it turns out to be only piecewise
continuous and so an alternate norm is employed to obtain a continuous
connection. The case when the two trajectories have different but rational
periods is also solved. The problem of connecting periodic trajectories is of
interest because of the observation that the operating points of many
biological and artificial systems are limit cycles and so there is a need for a
unified optimal framework of connections between different operating points.
This paper is a first step towards that goal.


title:
Error Estimates of the Bloch Band-Based Gaussian Beam Superposition for
  the Schr\"odinger Equation

abstract:
  This work is concerned with asymptotic approximations of the semi-classical
Schr\"odinger equation in periodic media using Gaussian beams. For the
underlying equation, subject to a highly oscillatory initial data, a hybrid of
the Gaussian beam approximation and homogenization leads to the Bloch
eigenvalue problem and associated evolution equations for Gaussian beam
components in each Bloch band. We formulate a superposition of Bloch-band based
Gaussian beams to generate high frequency approximate solutions to the original
wave field. For initial data of a sum of finite number of band eigen-functions,
we prove that the first-order Gaussian beam superposition converges to the
original wave field at a rate of $\epsilon^{1/2}$, with $\epsilon$ the
semiclassically scaled constant, as long as the initial data for Gaussian beam
components in each band are prepared with same order of error or smaller. For a
natural choice of initial approximation, a rate of $\epsilon^{1/2}$ of initial
error is verified.


title:
Amplification of electromagnetic waves excited by a chain of propagating
  magnetic vortices in YBaCuO Josephson-junction arrays at 77K and above

abstract:
  When a soliton propagates in a discrete lattice it excites small-amplitude
linear waves in its wake. In a dc current-biased Josephson-junction (JJ) array
these manifest as electromagnetic (EM) waves excited by a (magnetic field
induced) chain of propagating magnetic vortices. When the vortex velocity and
the phase velocity of one of the excited EM waves match, phase-locking occurs.
This produces resonant steps in the current-voltage characteristics where
amplification of EM radiation occurs. We report the first observation of
phase-locking-induced amplification of EM radiation at 77K and above in JJ
arrays made of high temperature superconductors.


title:
The search for shock-excited H2 in Virgo spirals experiencing ram
  pressure stripping

abstract:
  We investigate the presence of shock-excited H2 in four Virgo cluster
galaxies that show clear evidence of ongoing ram pressure stripping.
Mid-infrared (MIR) spectral mapping of the rotational H2 emission lines were
performed using the Infrared Spectrograph (IRS) on board the Spitzer space
telescope. We target four regions along the leading side of galaxies where the
intracluster medium (ICM) appears to be pushing back the individual galaxy's
interstellar medium (ISM). For comparison purposes, we also study two regions
on the trailing side of these galaxies, a region within an edge-on disk and an
extraplanar star-forming region. We find a factor of 2.6 excess of warm H2/PAH
in our sample relative to the observed fractions in other nearby galaxies. We
attribute the H2/PAH excess to contributions of shock-excited H2 which is
likely to have been triggered by ongoing ram pressure interaction in our sample
galaxies. Ram pressure driven shocks may also be responsible for the elevated
fractions of [FeII/NeII] found in our sample.


title: Word-length entropies and correlations of natural language written texts

abstract:
  We study the frequency distributions and correlations of the word lengths of
ten European languages. Our findings indicate that a) the word-length
distribution of short words quantified by the mean value and the entropy
distinguishes the Uralic (Finnish) corpus from the others, b) the tails at long
words, manifested in the high-order moments of the distributions, differentiate
the Germanic languages (except for English) from the Romanic languages and
Greek and c) the correlations between nearby word lengths measured by the
comparison of the real entropies with those of the shuffled texts are found to
be smaller in the case of Germanic and Finnish languages.


title: Transition To Order After Hilltop Inflation

abstract:
  We investigate the rich nonlinear dynamics during the end of hilltop
inflation by numerically solving the coupled Klein-Gordon-Friedmann equations
in a expanding universe. In particular, we search for coherent, nonperturbative
configurations that may emerge due to the combination of nontrivial couplings
between the fields and resonant effects from the cosmological expansion. We
couple a massless field to the inflaton to investigate its effect on the
existence and stability of coherent configurations and the effective equation
of state at reheating. For parameters consistent with data from the Planck and
WMAP satellites, and for a wide range of couplings between the inflaton and the
massless field, we identify a transition from disorder to order characterized
by emergent oscillon-like configurations. We verify that these configurations
can contribute a maximum of roughly 30% of the energy density in the universe.
At late times their contribution to the energy density drops to about 3%, but
they remain long-lived on cosmological time-scales, being stable throughout our
simulations. Cosmological oscillon emergence is described using a new measure
of order in field theory known as relative configurational entropy.


title: Using Neural Network to Propose Solutions to Threats in Attack Patterns

abstract:
  In the last decade, a lot of effort has been put into securing software
application during development in the software industry. Software security is a
research field in this area which looks at how security can be weaved into
software at each phase of software development lifecycle (SDLC). The use of
attack patterns is one of the approaches that have been proposed for
integrating security during the design phase of SDLC. While this approach help
developers in identify security flaws in their software designs, the need to
apply the proper security capability that will mitigate the threat identified
is very important. To assist in this area, the uses of security patterns have
been proposed to help developers to identify solutions to recurring security
problems. However due to different types of security patterns and their
taxonomy, software developers are faced with the challenge of finding and
selecting appropriate security patterns that addresses the security risks in
their design. In this paper, we propose a tool based on Neural Network for
proposing solutions in form of security patterns to threats in attack patterns
matching attacking patterns. From the result of performance of the neural
network, we found out that the neural network was able to match attack patterns
to security patterns that can mitigate the threat in the attack pattern. With
this information developers are better informed in making decision on the
solution for securing their application.


title:
From Safety To Termination And Back: SMT-Based Verification For Lazy
  Languages

abstract:
  SMT-based verifiers have long been an effective means of ensuring safety
properties of programs. While these techniques are well understood, we show
that they implicitly require eager semantics; directly applying them to a lazy
language is unsound due to the presence of divergent sub-computations. We
recover soundness by composing the safety analysis with a termination analysis.
Of course, termination is itself a challenging problem, but we show how the
safety analysis can be used to ensure termination, thereby bootstrapping
soundness for the entire system. Thus, while safety invariants have long been
required to prove termination, we show how termination proofs can be to soundly
establish safety. We have implemented our approach in liquidHaskell, a
Refinement Type-based verifier for Haskell. We demonstrate its effectiveness
via an experimental evaluation using liquidHaskell to verify safety, functional
correctness and termination properties of real-world Haskell libraries,
totaling over 10,000 lines of code.


title: Diagnosing a strong topological insulator by quantum oscillations

abstract:
  We show how quantum oscillation measurements of surface states in an
insulator may allow to diagnose a strong topological insulator and distinguish
it from its weak or topologically trivial counterpart. The criterion is defined
by the parity of the number of fundamental frequencies in the surface-state
quantum oscillation spectrum: an even number of frequencies implies a weak or a
topologically trivial insulator, whereas an odd number points to a strong
topological insulator. We also discuss various aspects and issues related to
applying this criterion in practice.


title: Cavity-loss induced plateau in coupled cavity QED array

abstract:
  Nonequilibrium steady states are investigated in a coupled cavity QED array
system which is pumped by a thermal bath and dissipated through cavity loss. In
the coherent (non-zero photon amplitude) phase, plateau regions appear, where
the steady states become unchanged against the variation of the chemical
potential of the thermal bath. The cavity loss plays a crucial role for the
plateaus: the plateaus appear only if the cavity loss exists, and the photon
leakage current, which is induced by the loss, is essential to the mechanism of
the plateaus.


title: Structure of Random 312-Avoiding Permutations

abstract:
  We evaluate the probabilities of various events under the uniform
distribution on the set of 312-avoiding permutations of 1,...,N. We derive
exact formulas for the probability that the ith element of a random permutation
is a specific value less than i, and for joint probabilities of two such
events. In addition, we obtain asymptotic approximations to these probabilities
for large N when the elements are not close to the boundaries or to each other.
We also evaluate the probability that the graph of a random 312-avoiding
permutation has k specified decreasing points, and we show that for large N the
points below the diagonal look like trajectories of a random walk.


title:
A study on the turbulent transport of an advective nature in the fluid
  plasma

abstract:
  Advective nature of the electrostatic turbulent flux of plasma energy is
studied numerically in a nearly adiabatic state. Such a state is represented by
the Hasegawa-Mima equation that is driven by a noise that may model the
destabilization due to the phase mismatch of the plasma density and the
electric potential. The noise is assumed to be Gaussian and not to be invariant
under reflection along a direction $\hat s$. It is found that the flux density
induced by such noise is anisotropic: While it is random along $\hat s$, it is
not along the perpendicular direction ${\hat s}_\perp$ and the flux is not
diffusive. The renormalized response may be approximated as advective with the
velocity being proportional to $(k\rho_s)^2$ in the Fourier space $\vec k$.


title:
Discrete maximum principle for the weak Galerkin method for anisotropic
  diffusion problems

abstract:
  A weak Galerkin discretization of the boundary value problem of a general
anisotropic diffusion problem is studied for preservation of the maximum
principle. It is shown that the direct application of the $M$-matrix theory to
the stiffness matrix of the weak Galerkin discretization leads to a strong mesh
condition requiring all of the mesh dihedral angles to be strictly acute (a
constant-order away from 90 degrees). To avoid this difficulty, a reduced
system is considered and shown to satisfy the discrete maximum principle under
weaker mesh conditions. The discrete maximum principle is then established for
the full weak Galerkin approximation using the relations between the degrees of
freedom located on elements and edges. Sufficient mesh conditions for both
piecewise constant and general anisotropic diffusion matrices are obtained.
These conditions provide a guideline for practical mesh generation for
preservation of the maximum principle. Numerical examples are presented.


title:
Attosecond streaking of Cohen-Fano interferences in the photoionization
  of H$_2^+$

abstract:
  We present the first numerical simulation of the time delay in the
photoionization of the simplest diatomic molecule H$_2^+$ as observed by
attosecond streaking. We show that the strong variation of the
Eisenbud-Wigner-Smith time delay as a function of energy and emission angle
becomes observable in the streaking time shift provided laser field-induced
components are accounted for. The strongly enhanced photoemission time shifts
are traced to destructive Cohen-Fano (or two-center) interferences. Signatures
of these interferences in the streaking trace are shown to be enhanced when the
ionic fragments are detected in coincidence.


title:
Maximum Likelihood Signal Extraction Method Applied to 3.4 years of
  CoGeNT Data

abstract:
  CoGeNT has taken data for over 3 years, with 1136 live days of data
accumulated as of April 23, 2013. We report on the results of a maximum
likelihood analysis to extract any possible dark matter signal present in the
collected data. The maximum likelihood signal extraction uses 2-dimensional
probability density functions (PDFs) to characterize the anticipated variations
in dark matter interaction rates for given observable nuclear recoil energies
during differing periods of the Earth's annual orbit around the Sun. Cosmogenic
and primordial radioactivity backgrounds are characterized by their energy
signatures and in some cases decay half-lives. A third parameterizing variable
-- pulse rise-time -- is added to the likelihood analysis to characterize slow
rising pulses described in prior analyses. The contribution to each event
category is analyzed for various dark matter signal hypotheses including a dark
matter standard halo model and a case with free oscillation parameters (i.e.,
amplitude, period, and phase). The best-fit dark matter signal is in close
proximity to previously reported results. We find that the significance of the
extracted dark matter signal remains well below evidentiary at 1.7 $\sigma$.


title: Twofold fast arithmetic

abstract:
  Can we assure math computations by automatic verifying floating-point
accuracy? We define fast arithmetic (based on Dekker [1971]) over twofold
approximations $z\approx z_0+z_1$, such that $z_0$ is standard result and $z_1$
assesses inaccuracy $\Delta z_0=z-z_0$. We propose on-fly tracking $z_1$,
detecting if $\Delta z_0$ appears too high. We believe permanent tracking is
worth its cost. C++ test code for Intel AVX available via web.


title: Preconditioning in Expectation

abstract:
  We show that preconditioners constructed by random sampling can perform well
without meeting the standard requirements of iterative methods. When applied to
graph Laplacians, this leads to ultra-sparsifiers that in expectation behave as
the nearly-optimal ones given by [Kolla-Makarychev-Saberi-Teng STOC`10].
Combining this with the recursive preconditioning framework by [Spielman-Teng
STOC`04] and improved embedding algorithms, this leads to algorithms that solve
symmetric diagonally dominant linear systems and electrical flow problems in
expected time close to $m\log^{1/2}n$ .


title: A remark on the two-dimensional magneto-hydrodynamics-alpha system

abstract:
  We study the two-dimensional generalized magnetohydrodynamics-$\alpha$ system
with fractional Laplacians in the dissipative and diffusive terms. We show that
the solution pair of velocity and magnetic fields preserves their initial
regularity in all cases when the powers add up to one. This settles the global
regularity issue in the general case which was remarked by the authors in [33]
to be a problem.


title:
Fast Hankel Tensor-Vector Products and Application to Exponential Data
  Fitting

abstract:
  This paper is contributed to a fast algorithm for Hankel tensor-vector
products. For this purpose, we first discuss a special class of Hankel tensors
that can be diagonalized by the Fourier matrix, which is called
\emph{anti-circulant} tensors. Then we obtain a fast algorithm for Hankel
tensor-vector products by embedding a Hankel tensor into a larger
anti-circulant tensor. The computational complexity is about $\mathcal{O}(m^2 n
\log mn)$ for a square Hankel tensor of order $m$ and dimension $n$, and the
numerical examples also show the efficiency of this scheme. Moreover, the block
version for multi-level block Hankel tensors is discussed as well. Finally, we
apply the fast algorithm to exponential data fitting and the block version to
2D exponential data fitting for higher performance.


title:
Local perturbations of the upper layers of a Sun-like star: the impact
  on the acoustic oscillation spectrum

abstract:
  In the last decade the quality and the amount of observational asteroseismic
data that has been made available by space based missions had a tremendous
upgrowth. The determination of asteroseismic parameters to estimate the
fundamental physical processes occurring in stars' interiors, can be done today
in a way that has never been possible before. In this work we propose to
compute the seismic observable $\beta$, which is a proxy of the phase shift of
the acoustic modes propagating in the envelope of the Sun-like stars. This
seismic parameter $\beta$ can be used to identify rapid variation regions
usually known as glitches. We show that a small variation in the structure,
smaller than 1% in the sound speed, produces a glitch in the acoustic potential
that could explain the oscillatory character of $\beta$. This method allows us
to determine the location and the thickness of the glitch with precision. We
applied this idea to the Sun-like star $\alpha$ Centauri A and found a glitch
located at approximately $0.94\,R$ (1400 s) and with a thickness of 0.2% of the
stars' radius. This is fully consistent with the data and also validates other
seismic tests.


title: Is Extreme Learning Machine Feasible? A Theoretical Assessment (Part II)

abstract:
  An extreme learning machine (ELM) can be regarded as a two stage feed-forward
neural network (FNN) learning system which randomly assigns the connections
with and within hidden neurons in the first stage and tunes the connections
with output neurons in the second stage. Therefore, ELM training is essentially
a linear learning problem, which significantly reduces the computational
burden. Numerous applications show that such a computation burden reduction
does not degrade the generalization capability. It has, however, been open that
whether this is true in theory. The aim of our work is to study the theoretical
feasibility of ELM by analyzing the pros and cons of ELM. In the previous part
on this topic, we pointed out that via appropriate selection of the activation
function, ELM does not degrade the generalization capability in the expectation
sense. In this paper, we launch the study in a different direction and show
that the randomness of ELM also leads to certain negative consequences. On one
hand, we find that the randomness causes an additional uncertainty problem of
ELM, both in approximation and learning. On the other hand, we theoretically
justify that there also exists an activation function such that the
corresponding ELM degrades the generalization capability. In particular, we
prove that the generalization capability of ELM with Gaussian kernel is
essentially worse than that of FNN with Gaussian kernel. To facilitate the use
of ELM, we also provide a remedy to such a degradation. We find that the
well-developed coefficient regularization technique can essentially improve the
generalization capability. The obtained results reveal the essential
characteristic of ELM and give theoretical guidance concerning how to use ELM.


title:
Photo-oxidative tuning of individual and coupled GaAs photonic crystal
  cavities

abstract:
  We demonstrate a new photo-induced oxidation technique for tuning GaAs
photonic crystal cavities using a $390~\mathrm{nm}$ pulsed laser with an
average power of $10~\mathrm{\mu W}$. The laser oxidizes a small $\left(\sim
500~\mathrm{nm}\right)$ diameter spot, reducing the local index of refraction
and blueshifting the cavity. The tuning progress can be actively monitored in
real time. We also demonstrate tuning an individual cavity within a pair of
proximity-coupled cavities, showing that this method can be used to correct
undesired frequency shifts caused by fabrication imperfections in cavity
arrays.