title:
On the graph-theoretical interpretation of Pearson correlations in a
  multivariate process and a novel partial correlation measure

abstract:
  The dependencies of the lagged (Pearson) correlation function on the
coefficients of multivariate autoregressive models are interpreted in the
framework of time series graphs. Time series graphs are related to the concept
of Granger causality and encode the conditional independence structure of a
multivariate process. The authors show that the complex dependencies of the
Pearson correlation coefficient complicate an interpretation and propose a
novel partial correlation measure with a straightforward graph-theoretical
interpretation. The novel measure has the additional advantage that its
sampling distribution is not affected by serial dependencies like that of the
Pearson correlation coefficient. In an application to climatological time
series the potential of the novel measure is demonstrated.


title: Ultrafast thermally induced magnetic switching in synthetic ferrimagnets

abstract:
  Synthetic ferrimagnets are composite magnetic structures formed from two or
more anti- ferromagnetically coupled magnetic sublattices with different
magnetic moments. Here we report on atomistic spin simulations of the
laser-induced magnetization dynamics on such synthetic ferrimag- nets, and
demonstrate that the application of ultrashort laser pulses leads to
sub-picoscond magnetization dynamics and all-optical switching in a similar
manner as in ferrimagnetic alloys. Moreover, we present the essential material
properties for successful laser-induced switching, demonstrating the
feasibility of using a synthetic ferrimagnet as a high density magnetic storage
element without the need of a write field.


title: Nuclear charge radii of potassium isotopes beyond N=28

abstract:
  We report on the measurement of optical isotope shifts for
$^{38,39,42,44,46\text{-}51}$K relative to $^{47}$K from which changes in the
nuclear mean square charge radii across the N=28 shell closure are deduced. The
investigation was carried out by bunched-beam collinear laser spectroscopy at
the CERN-ISOLDE radioactive ion-beam facility. Mean square charge radii are now
known from $^{37}$K to $^{51}$K, covering all $\nu f_{7/2}$-shell as well as
all $\nu p_{3/2}$-shell nuclei. These measurements, in conjunction with those
of Ca, Cr, Mn and Fe, provide a first insight into the $Z$ dependence of the
evolution of nuclear size above the shell closure at N=28.


title: Cycle-maximal triangle-free graphs

abstract:
  We conjecture that the balanced complete bipartite graph $K_{\lfloor n/2
\rfloor,\lceil n/2 \rceil}$ contains more cycles than any other $n$-vertex
triangle-free graph, and we make some progress toward proving this. We give
equivalent conditions for cycle-maximal triangle-free graphs; show bounds on
the numbers of cycles in graphs depending on numbers of vertices and edges,
girth, and homomorphisms to small fixed graphs; and use the bounds to show that
among regular graphs, the conjecture holds. We also consider graphs that are
close to being regular, with the minimum and maximum degrees differing by at
most a positive integer $k$. For $k=1$, we show that any such counterexamples
have $n\le 91$ and are not homomorphic to $C_5$; and for any fixed $k$ there
exists a finite upper bound on the number of vertices in a counterexample.
Finally, we describe an algorithm for efficiently computing the matrix
permanent (a #P-complete problem in general) in a special case used by our
bounds.


title:
A Neumann problem involving the $p(x)$-Laplacian with $p=\infty$ in a
  subdomain

abstract:
  In this paper we study a non-homogeneous Neumann problem, where the
$p(x)$-Laplacian is involved and $p=\infty$ in a subdomain. By considering a
suitable sequence $p_k$ of bounded variable exponents such that $p_k \to p$ and
replacing $p$ with $p_k$ in the original problem, we prove the existence of a
solution $u_k$ for each of those intermediate ones. We show that the limit of
the $u_k$ exists and after giving a variational characterization of it, in the
part of the domain where $p$ is bounded, we show that it is a viscosity
solution in the part where $p=\infty$. Finally, we formulate the problem of
which this limit function is a solution in the viscosity sense.


title: On the definition and K-theory realization of a modular functor

abstract:
  We present a definition of a (super)-modular functor which includes certain
interesting cases that previous definitions do not allow. We also introduce a
notion of topological twisting of a modular functor, and construct formally a
realization by a 2-dimensional topological field theory valued in twisted
K-modules. We discuss, among other things, the N=1-supersymmetric minimal
models from the point of view of this formalism.


title: On level sets of Gaussian fields

abstract:
  In this short note, we present a theorem concerning certain "additive
structure" for the level sets of non-degenerate Gaussian fields, which yields
the multiple valley phenomenon for extremal fields with exponentially many
valleys.


title: Jacobi photonic lattices and their SUSY partners

abstract:
  We present a classical analog of quantum optical deformed oscillators in
arrays of waveguides. The normal modes of these one-dimensional photonic
crystals are given in terms of Jacobi polynomials. We show that it is possible
to attack the problem via factorization by exploiting the quantum optical
analogy. This allows us to provide an unbroken supersymmetric partner of the
proposed Jacobi lattices. Thanks to the underlying SU(1,1) group symmetry of
the lattices, we present the analytic propagators and impulse functions for
these one-dimensional photonic crystals.


title:
The SWELLS Survey. VI. hierarchical inference of the initial mass
  functions of bulges and discs

abstract:
  The long-standing assumption that the stellar initial mass function (IMF) is
universal has recently been challenged by a number of observations. Several
studies have shown that a "heavy" IMF (e.g., with a Salpeter-like abundance of
low mass stars and thus normalisation) is preferred for massive early-type
galaxies, while this IMF is inconsistent with the properties of less massive,
later-type galaxies. These discoveries motivate the hypothesis that the IMF may
vary (possibly very slightly) across galaxies and across components of
individual galaxies (e.g. bulges vs discs). In this paper we use a sample of 19
late-type strong gravitational lenses from the SWELLS survey to investigate the
IMFs of the bulges and discs in late-type galaxies. We perform a joint analysis
of the galaxies' total masses (constrained by strong gravitational lensing) and
stellar masses (constrained by optical and near-infrared colours in the context
of a stellar population synthesis [SPS] model, up to an IMF normalisation
parameter). Using minimal assumptions apart from the physical constraint that
the total stellar mass within any aperture must be less than the total mass
within the aperture, we find that the bulges of the galaxies cannot have IMFs
heavier (i.e. implying high mass per unit luminosity) than Salpeter, while the
disc IMFs are not well constrained by this data set. We also discuss the
necessity for hierarchical modelling when combining incomplete information
about multiple astronomical objects. This modelling approach allows us to place
upper limits on the size of any departures from universality. More data,
including spatially resolved kinematics (as in paper V) and stellar population
diagnostics over a range of bulge and disc masses, are needed to robustly
quantify how the IMF varies within galaxies.

categories: astro-ph.IM astro-ph.GA physics.data-an stat.AP


title: Eigenvalues of the Neumann Laplacian in symmetric regions

abstract:
  In this work we are concerned with the multiplicity of the eigenvalues of the
Neumann Laplacian in regions of Rn which are invariant under the natural action
of a compact subgroup G of O(n). We give a partial positive answer (in the
Neumann case) to a conjecture of V. Arnold [1] on the transversality of the
transformation given by the Dirichlet integral to the stratification in the
space of quadratic forms according to the multiplicities of the eigenvalues. We
show, for some classes of subgroups of O(n) that, generically in the set of
G-invariant, C2-regions, the action is irreducible in each eigenspace. These
classes include finite subgroups with irreducible representations of dimension
not greater than 2 and, in the case n=2, any compact subgroup of O(2). We also
obtain some partial results for general compact subgroups of O(n).


title:
Observations of low- and intermediate-frequency-peaked BL Lacs above 100
  GeV with VERITAS

abstract:
  Most of the ~50 blazars detected to date at TeV energies (E>0.1 TeV) are
high-frequency-peaked BL Lacs (HBLs). Only a handful episodic TeV detections of
low- and intermediate-frequency-peaked BL Lacs (LBL/IBLs, with synchrotron peak
frequencies in the infrared and optical regime) have been reported, typically
during high-flux states. The VERITAS array, a ground-based TeV observatory
located in southern Arizona has observed five known TeV LBL/IBLs since 2009: 3C
66A, W Comae, PKS 1424+240, S5 0716+714 and BL Lacertae, with at least 5-10
hours/year, which so far resulted in the detection of a bright, sub-hour
timescale gamma-ray flare of BL Lacertae in June 2011. We also report the
detection and characterization of two new IBLs: VER J0521+211 and B2 1215+30.


title:
Weyl spin-orbit-coupling-induced interactions in uniform and trapped
  atomic quantum fluids

abstract:
  We establish through analytical and numerical studies of thermodynamic
quantities for noninteracting atomic gases that the isotropic three-dimensional
spin-orbit coupling, the Weyl coupling, induces interaction which counters
"effective" attraction (repulsion) of the exchange symmetry present in
zero-coupling Bose (Fermi) gas. The exact analytical expressions for the grand
potential and hence for several thermodynamic quantities have been obtained for
this purpose in both uniform and trapped cases. It is enunciated that many
interesting features of spin-orbit coupled systems revealed theoretically can
be understood in terms of coupling-induced modifications in statistical
interparticle potential. The temperature-dependence of the chemical potential,
specific heat and isothermal compressibility for a uniform Bose gas is found to
have signature of the incipient Bose-Einstein condensation in very weak
coupling regime although the system does not really go in the Bose-condensed
phase. The transition temperature in harmonically trapped case decreases with
increase of coupling strength consistent with the weakening of the statistical
attractive interaction. Anomalous behavior of some thermodynamic quantities,
partly akin to that in dimensions less than two, appears for uniform fermions
as soon as the Fermi level goes down the Dirac point on increasing the coupling
strength. It is suggested that the fluctuation-dissipation theorem can be
utilized to verify anomalous behaviors from studies of long-wavelength
fluctuations in bunching and antibunching effects.


title: Strong field electrodynamics of a thin foil

abstract:
  Exact solutions describing the nonlinear electrodynamics of a thin double
layer foil are presented. These solutions correspond to a broad range of
problems of interest for the interaction of high intensity laser pulses with
overdense plasmas such as frequency upshifting, high order harmonic generation
and high energy ion acceleration.


title: Massively parallel approximate Gaussian process regression

abstract:
  We explore how the big-three computing paradigms -- symmetric multi-processor
(SMC), graphical processing units (GPUs), and cluster computing -- can together
be brought to bare on large-data Gaussian processes (GP) regression problems
via a careful implementation of a newly developed local approximation scheme.
Our methodological contribution focuses primarily on GPU computation, as this
requires the most care and also provides the largest performance boost.
However, in our empirical work we study the relative merits of all three
paradigms to determine how best to combine them. The paper concludes with two
case studies. One is a real data fluid-dynamics computer experiment which
benefits from the local nature of our approximation; the second is a synthetic
data example designed to find the largest design for which (accurate) GP
emulation can performed on a commensurate predictive set under an hour.


title:
Cone of Darkness: Finding Blank-sky Positions for Multi-object
  Wide-field Observations

abstract:
  We present the Cone of Darkness, an application to automatically configure
blank-sky positions for a series of stacked, wide-field observations, such as
those carried out by the SAMI instrument on the Anglo-Australian Telescope
(AAT). The Sydney-AAO Multi-object Integral field spectrograph (SAMI) uses a
plug-plate to mount its $13 \times 61$ core imaging fibre bundles (hexabundles)
in the optical plane at the telescope's prime focus. To make the most efficient
use of each plug-plate, several observing fields are typically stacked to
produce a single plate. When choosing blank-sky positions for the observations
it is most effective to select these such that one set of 26 holes gives valid
sky positions for all fields on the plate. However, when carried out manually
this selection process is tedious and includes a significant risk of error. The
Cone of Darkness software aims to provide uniform blank-sky position coverage
over the field of observation, within the limits set by the distribution of
target positions and the chosen input catalogues. This will then facilitate the
production of the best representative median sky spectrum for use in sky
subtraction. The application, written in C++, is configurable, making it usable
for a range of instruments. Given the plate characteristics and the positions
of target holes, the software segments the unallocated space on the plate and
determines the position which best fits the uniform distribution requirement.
This position is checked, for each field, against the selected catalogue using
a TAP ADQL search. The process is then repeated until the desired number of sky
positions is attained.


title:
Spin polarization oscillations in a magnetically inhomogeneous
  conducting ring

abstract:
  The real part of the conductance of a 1D conducting ring with magnetic
properties that vary along the conductor is examined. The possibility of
exciting a new type of spin polarization oscillations in the ring with an
external emf is analyzed.


title: Adversary Lower Bounds for the Collision and the Set Equality Problems

abstract:
  We prove tight $\Omega(n^{1/3})$ lower bounds on the quantum query complexity
of the Collision and the Set Equality problems, provided that the size of the
alphabet is large enough. We do this using the negative-weight adversary
method. Thus, we reprove the result by Aaronson and Shi, as well as a more
recent development by Zhandry.


title: Strong Planck constraints on braneworld and non-commutative inflation

abstract:
  We place observational likelihood constraints on braneworld and
non-commutative inflation for a number of inflaton potentials, using Planck,
WMAP polarization and BAO data. Both braneworld and non-commutative scenarios
of the kind considered here are limited by the most recent data even more
severely than standard general-relativity models. At more than 95 % confidence
level, the monomial potential $V(\phi) \propto \phi^p$ is ruled out for $p \geq
2$ in the Randall--Sundrum (RS) braneworld cosmology and, for $p>0$, also in
the high-curvature limit of the Gauss--Bonnet (GB) braneworld and in the
infrared limit of non-commutative inflation, due to a large scalar spectral
index. Some parameter values for natural inflation, small-varying inflaton
models and Starobinsky inflation are allowed in all scenarios, although some
tuning is required for natural inflation in a non-commutative spacetime.


title: Distributed Reed-Solomon Codes for Simple Multiple Access Networks

abstract:
  We consider a simple multiple access network in which a destination node
receives information from multiple sources via a set of relay nodes. Each relay
node has access to a subset of the sources, and is connected to the destination
by a unit capacity link. We also assume that $z$ of the relay nodes are
adversarial. We propose a computationally efficient distributed coding scheme
and show that it achieves the full capacity region for up to three sources.
Specifically, the relay nodes encode in a distributed fashion such that the
overall codewords received at the destination are codewords from a single
Reed-Solomon code.


title:
The Very Young Type Ia Supernova 2013dy: Discovery, and Strong Carbon
  Absorption in Early-Time Spectra

abstract:
  The Type Ia supernova (SN Ia) 2013dy in NGC 7250 (d ~ 13.7 Mpc) was
discovered by the Lick Observatory Supernova Search. Combined with a
prediscovery detection by the Italian Supernova Search Project, we are able to
constrain the first-light time of SN 2013dy to be only 0.10 +/- 0.05 d (2.4 +/-
1.2 hr) before the first detection. This makes SN 2013dy the earliest known
detection of an SN Ia. We infer an upper limit on the radius of the progenitor
star of R_0 < 0.25 R_sun, consistent with that of a white dwarf. The light
curve exhibits a broken power law with exponents of 0.88 and then 1.80. A
spectrum taken 1.63 d after first light reveals a C II absorption line
comparable in strength to Si II. This is the strongest C II feature ever
detected in a normal SN Ia, suggesting that the progenitor star had significant
unburned material. The C II line in SN 2013dy weakens rapidly and is undetected
in a spectrum 7 days later, indicating that C II is detectable for only a very
short time in some SNe Ia. SN 2013dy reached a B-band maximum of M_B = -18.72
+/- 0.03 mag ~17.7 d after first light.


title: Report of the Snowmass 2013 energy frontier QCD working group

abstract:
  This is the summary report of the energy frontier QCD working group prepared
for Snowmass 2013. We review the status of tools, both theoretical and
experimental, for understanding the strong interactions at colliders. We
attempt to prioritize important directions that future developments should
take. Most of the efforts of the QCD working group concentrate on proton-proton
colliders, at 14 TeV as planned for the next run of the LHC, and for 33 and 100
TeV, possible energies of the colliders that will be necessary to carry on the
physics program started at 14 TeV. We also examine QCD predictions and
measurements at lepton-lepton and lepton-hadron colliders, and in particular
their ability to improve our knowledge of strong coupling constant and parton
distribution functions.


title: Neutral gas sympathetic cooling of an ion in a Paul trap

abstract:
  A single ion immersed in a neutral buffer gas is studied. An analytical model
is developed that gives a complete description of the dynamics and steady-state
properties of the ions. An extension of this model, using techniques borrowed
from the mathematics of finance, is used to explain the recent observation of
non-Maxwellian statistics for these systems. Taken together, these results
offer an explanation of the longstanding issues associated with sympathetic
cooling of an ion by a neutral buffer gas.


title: Modules with Demazure Flags and Character Formulae

abstract:
  In this paper we study a family of finite-dimensional graded representations
of the current algebra of $\mathfrak{sl}_2$ which are indexed by partitions.
  We show that these representations admit a flag where the successive
quotients are Demazure modules which occur in a level $\ell$-integrable module
for $A_1^1$ as long as $\ell$ is large. We associate to each partition and to
each $\ell$ an edge-labeled directed graph which allows us to describe in a
combinatorial way the graded multiplicity of a given level $\ell$-Demazure
module in the filtration. In the special case of the partition $1^s$ and
$\ell=2$, we give a closed formula for the graded multiplicity of level two
Demazure modules in a level one Demazure module. As an application, we use our
result along with the results of Naoi and Lenart et al., to give the character
of a $\mathfrak{g}$-stable level one Demazure module associated to $B_n^1$ as
an explicit combination of suitably specialized Macdonald polynomials. In the
case of $\mathfrak{sl}_2$, we also study the filtration of the level two
Demazure module by level three Demazure modules and compute the numerical
filtration multiplicities and show that the graded multiplicites are related to
(variants of) partial theta series.


title: Evolutionary games on the lattice: best-response dynamics

abstract:
  The best-response dynamics is an example of an evolutionary game where
players update their strategy in order to maximize their payoff. The main
objective of this paper is to study a stochastic spatial version of this game
based on the framework of interacting particle systems in which players are
located on an infinite square lattice. In the presence of two strategies, and
calling a strategy selfish or altruistic depending on a certain ordering of the
coefficients of the underlying payoff matrix, a simple analysis of the
non-spatial mean-field approximation of the spatial model shows that a strategy
is evolutionary stable if and only if it is selfish, making the system bistable
when both strategies are selfish. The spatial and non-spatial models agree when
at least one strategy is altruistic. In contrast, we prove that, in the
presence of two selfish strategies and in any spatial dimensions, only the most
selfish strategy remains evolutionary stable. The main ingredients of the proof
are monotonicity results and a coupling between the best-response dynamics
properly rescaled in space with bootstrap percolation to compare the infinite
time limits of both systems.


title: Immersions and the space of all translation structures

abstract:
  A translation structure on a surface is an atlas of charts to the plane so
that the transition functions are translations. We allow our surfaces to be
non-compact and infinite genus. We endow the space of all pointed surfaces
equipped with a translation structure with a topology, which we call the
immersive topology because it is related to the manner in which disks can be
immersed into such a surface. We prove that a number of operations typically
done to translation surfaces are continuous with respect to the topology. We
show that the topology is Hausdorff, and that the collection of surfaces with a
fixed lower bound on the injectivity radius at the basepoint is compact.


title:
Crossover between Weak Antilocalization and Weak Localization of Bulk
  States in Ultrathin Bi2Se3 Films

abstract:
  We report transport studies on the 5 nm thick Bi2Se3 topological insulator
films which are grown via molecular beam epitaxy technique. The angle-resolved
photoemission spectroscopy data show that the Fermi level of the system lies in
the bulk conduction band above the Dirac point, suggesting important
contribution of bulk states to the transport results. In particular, the
crossover from weak antilocalization to weak localization in the bulk states is
observed in the parallel magnetic field measurements up to 50 Tesla. The
measured magneto-resistance exhibits interesting anisotropy with respect to the
orientation of B// and I, signifying intrinsic spin-orbit coupling in the
Bi2Se3 films. Our work directly shows the crossover of quantum interference
effect in the bulk states from weak antilocalization to weak localization. It
presents an important step toward a better understanding of the existing
three-dimensional topological insulators and the potential applications of
nano-scale topological insulator devices.


title:
A mathematical theory of D-string world-sheet instantons, II: Moduli
  stack of $Z$-(semi)stable morphisms from Azumaya nodal curves with a
  fundamental module to a projective Calabi-Yau 3-fold

abstract:
  In this Part II, D(10.2), of D(10), we take D(10.1) (arXiv:1302.2054
[math.AG]) as the foundation to define the notion of $Z$-semistable morphisms
from general Azumaya nodal curves, of genus $\ge 2$, with a fundamental module
to a projective Calabi-Yau 3-fold and show that the moduli stack of such
$Z$-semistable morphisms of a fixed type is compact. This gives us a counter
moduli stack to D-strings as the moduli stack of stable maps in Gromov-Witten
theory to the fundamental string. It serves and prepares for us the basis
toward a new invariant of Calabi-Yau 3-fold that captures soft-D-string
world-sheet instanton numbers in superstring theory. This note is written
hand-in-hand with D(10.1) and is to be read side-by-side with ibidem.


title:
When Viscous Jets Collide; Liquid Chains, Threads, Webs, Fishbones and
  Balloons

abstract:
  In this fluid dynamics video prepared for the APS-DFD Gallery of Fluid Motion
we study the collision of two identical viscous jets at different jet speeds
and collision eccentricities. The dynamics of the jet motion are slowed down by
orders of magnitude using a synchronized strobe effect coupled with precise
timing control of the perturbation frequency imposed on one of the jets. Our
results show that different shapes and morphologies appear as we change the
collision eccentricity. At low jet speeds ($We_j = 45$) viscous threads and
filaments are formed as the jets begin to impinge on each other. As the
propagation axis of one of the jets (jet A) is moved closer to the center of
the other stream (jet B) they exert a torque on each other. Because of the
resulting swirl, jet A rotates around the axis of jet B and finally breaks into
droplets through the action of capillary forces; the pinch off of droplets is
similar to a stream of balloons which are released in the air. At zero
eccentricity the two jets unite into one jet at low speed and the unified jet
breaks up after undergoing Rayleigh-Plateau instability. For higher jet
velocities ($We_j=125$) different morphologies develop; at high eccentricities
of impact (0.95), threads will appear; triangular sheets or webs form at
eccentricities close to 0.9 and as one jet moves closer to the center of the
other one first partial/incomplete fishbones appear and eventually
periodically-dancing fishbones develop.


title: Vector cross product in n-dimensional vector space

abstract:
  The definition of vector cross product (VCP) introduced by Eckmann only
exists in thethree- and the seven- dimensional vector space. In this paper,
according to the orthogonal completeness, magnitude of basis vector cross
product and all kinds of combinations of basis vector $\hat{e}_i$, the
generalized definition of VCP in the odd n-dimensional vector space is given by
introducing a cross term $X_{AB}$. In addition, the definition is validated by
reducing the generalization definition to the fundamental three- and
seven-dimensional vector space.


title: Artin prime producing polynomials

abstract:
  We define an Artin prime for an integer $g$ to be a prime such that $g$ is a
primitive root modulo that prime. Let $g\in \mathbb{Z}\setminus\{-1\}$ and not
be a perfect square. A conjecture of Artin states that the set of Artin primes
for $g$ has a positive density. In this paper we study a generalization of this
conjecture for the primes produced by a polynomial and explore its connection
with the problem of finding a fixed integer $g$ and a prime producing
polynomial $f(x)$ with the property that a long string of consecutive primes
produced by $f(x)$ are Artin primes for $g$. By employing some results of
Moree, we propose a general method for finding such polynomials $f(x)$ and
integers $g$. We then apply this general procedure for linear, quadratic, and
cubic polynomials to generate many examples of polynomials with very large
Artin prime production length. More specifically, among many other examples, we
exhibit linear, quadratic, and cubic (respectively) polynomials with 6355,
37951, and 10011 (respectively) consecutive Artin primes for certain integers
$g$.


title: A Notion of Robustness for Cyber-Physical Systems

abstract:
  Robustness as a system property describes the degree to which a system is
able to function correctly in the presence of disturbances, i.e., unforeseen or
erroneous inputs. In this paper, we introduce a notion of robustness termed
input-output dynamical stability for cyber-physical systems (CPS) which merges
existing notions of robustness for continuous systems and discrete systems. The
notion captures two intuitive aims of robustness: bounded disturbances have
bounded effects and the consequences of a sporadic disturbance disappear over
time. We present a design methodology for robust CPS which is based on an
abstraction and refinement process. We suggest several novel notions of
simulation relations to ensure the soundness of the approach. In addition, we
show how such simulation relations can be constructed compositionally. The
different concepts and results are illustrated throughout the paper with
examples.


title:
Magic mass ratios of complete energy-momentum transfer in
  one-dimensional elastic three-body collisions

abstract:
  We consider the one-dimensional scattering of two identical blocks of mass
$M$ that exchange energy and momentum via elastic collisions with an
intermediary ball of mass $m=\alpha M$. Initially, one block is incident upon
the ball with the other block at rest. For $\alpha<1$, the three objects will
make multiple collisions with one another. In our analysis, we construct a
Euclidean vector $\textbf{V}_n$ whose components are proportional to the
velocities of the objects. Energy-momentum conservation then requires a
covariant recurrence relation for $\textbf{V}_n$ that transforms like a pure
rotation in three dimensions. The analytic solutions of the terminal velocities
result in a remarkable prediction for values of $\alpha$, in cases where the
initial energy and momentum of the incident block are completely transferred to
the scattered block. We call these values for $\alpha$ "magic mass ratios."


title: Homomesy in products of two chains

abstract:
  Many invertible actions $\tau$ on a set ${\mathcal{S}}$ of combinatorial
objects, along with a natural statistic $f$ on ${\mathcal{S}}$, exhibit the
following property which we dub \textbf{homomesy}: the average of $f$ over each
$\tau$-orbit in ${\mathcal{S}}$ is the same as the average of $f$ over the
whole set ${\mathcal{S}}$. This phenomenon was first noticed by Panyushev in
2007 in the context of the rowmotion action on the set of antichains of a root
poset; Armstrong, Stump, and Thomas proved Panyushev's conjecture in 2011. We
describe a theoretical framework for results of this kind that applies more
broadly, giving examples in a variety of contexts. These include linear actions
on vector spaces, sandpile dynamics, Suter's action on certain subposets of
Young's Lattice, Lyness 5-cycles, promotion of rectangular semi-standard Young
tableaux, and the rowmotion and promotion actions on certain posets. We give a
detailed description of the latter situation for products of two chains.


title: Discriminative Measures for Comparison of Phylogenetic Trees

abstract:
  In this paper we introduce and study three new measures for efficient
discriminative comparison of phylogenetic trees. The NNI navigation
dissimilarity $d_{nav}$ counts the steps along a "combing" of the Nearest
Neighbor Interchange (NNI) graph of binary hierarchies, providing an efficient
approximation to the (NP-hard) NNI distance in terms of "edit length". At the
same time, a closed form formula for $d_{nav}$ presents it as a weighted count
of pairwise incompatibilities between clusters, lending it the character of an
edge dissimilarity measure as well. A relaxation of this formula to a simple
count yields another measure on all trees --- the crossing dissimilarity
$d_{CM}$. Both dissimilarities are symmetric and positive definite (vanish only
between identical trees) on binary hierarchies but they fail to satisfy the
triangle inequality. Nevertheless, both are bounded below by the widely used
Robinson-Foulds metric and bounded above by a closely related true metric, the
cluster-cardinality metric $d_{CC}$. We show that each of the three proposed
new dissimilarities is computable in time $O(n^2)$ in the number of leaves $n$,
and conclude the paper with a brief numerical exploration of the distribution
over tree space of these dissimilarities in comparison with the Robinson-Foulds
metric and the more recently introduced matching-split distance.


title:
Application of Group Analysis to Classification of Systems of Three
  Second-Order Ordinary Differential Equations

abstract:
  Here we give a complete group classification of the general case of linear
systems of three second-order ordinary differential equations excluding the
case of systems which are studied in the literature. This is given as the
initial step in the study of nonlinear systems of three second-order ordinary
differential equations. In addition the complete group classification of a
system of three linear second-order ordinary differential equations is done.
Four cases of linear systems of equations are obtained.


title:
Amplification without inversion, fast light and optical bistability in a
  duplicated two-level system

abstract:
  The optical properties of a weak probe field in a duplicated two-level system
are investigated in multiphoton resonance (MPR) condition and beyond it. It is
shown that, by changing the relative phase of applied fields, the absorption
switches to the amplification without inversion in MPR condition. By applying
the Floquet decomposition to the equation of motion beyond MPR condition, it is
shown that the phase-dependent behavior is valid only in MPR condition.
Moreover, it is demonstrated that the group velocity of light pulse can be
controlled by the intensity of applied fields and the gain-assisted
superluminal light propagation (fast light) is obtained in this system. In
addition, the optical bistability (OB) behavior of the system is studied beyond
MPR condition. We apply an indirect incoherent pumping field to the system and
it is found that the group velocity and OB behavior of the system can be
controlled by incoherent pumping rate.


title:
Robustness of Network of Networks with Interdependent and Interconnected
  links

abstract:
  Robustness of network of networks (NON) has been studied only for dependency
coupling (J.X. Gao et. al., Nature Physics, 2012) and only for connectivity
coupling (E.A. Leicht and R.M. D Souza, arxiv:0907.0894). The case of network
of n networks with both interdependent and interconnected links is more
complicated, and also more closely to real-life coupled network systems. Here
we develop a framework to study analytically and numerically the robustness of
this system. For the case of starlike network of n ER networks, we find that
the system undergoes from second order to first order phase transition as
coupling strength q increases. We find that increasing intra-connectivity links
or inter-connectivity links can increase the robustness of the system, while
the interdependency links decrease its robustness. Especially when q=1, we find
exact analytical solutions of the giant component and the first order
transition point. Understanding the robustness of network of networks with
interdependent and interconnected links is helpful to design resilient
infrastructures.


title:
Linearized stability for a multi-dimensional free boundary problem
  modeling two-phase tumor growth

abstract:
  This paper is concerned with a multi-dimensional free boundary problem
modeling the growth of a tumor with two species of cells: proliferating cells
and quiescent cells. This free boundary problem has a unique radial stationary
solution. By using the Fourier expansion of functions on unit sphere via
spherical harmonics, we establish some decay estimates for the solution of the
linearized system of this tumor model at the radial stationary solution, so
that proving that the radial stationary solution is linearly asymptotically
stable when neglecting translations.


title:
A Radial Basis Function (RBF)-Finite Difference Method for the
  Simulation of Reaction-Diffusion Equations on Stationary Platelets within the
  Augmented Forcing Method

abstract:
  We present a computational method for solving the coupled problem of chemical
transport in a fluid (blood) with binding/unbinding of the chemical to/from
cellular (platelet) surfaces in contact with the fluid, and with transport of
the chemical on the cellular surfaces. The overall framework is the Augmented
Forcing Point Method (AFM) (\emph{L. Yao and A.L. Fogelson, Simulations of
chemical transport and reaction in a suspension of cells I: An augmented
forcing point method for the stationary case, IJNMF (2012) 69, 1736-52.}) for
solving fluid-phase transport in a region outside of a collection of cells
suspended in the fluid. We introduce a novel Radial Basis Function-Finite
Difference (RBF-FD) method to solve reaction-diffusion equations on the surface
of each of a collection of 2D stationary platelets suspended in blood.
Parametric RBFs are used to represent the geometry of the platelets and give
accurate geometric information needed for the RBF-FD method. Symmetric
Hermite-RBF interpolants are used for enforcing the boundary conditions on the
fluid-phase chemical concentration, and their use removes a significant
limitation of the original AFM. The efficacy of the new methods are shown
through a series of numerical experiments; in particular, second order
convergence for the coupled problem is demonstrated.


title: Improved Error-Tradeoff and Error-Disturbance Relations

abstract:
  Heisenberg's uncertainty principle is quantified by error-disturbance
tradeoff relations, which have been tested experimentally in various scenarios.
Here we shall report improved new versions of various error-disturbance
tradeoff relations by decomposing the measurement errors into two different
components, namely, operator bias and fuzziness. Our improved uncertainty
relations reveal the tradeoffs between these two components of errors, and
imply various conditionally valid error-tradeoff relations for the unbiased and
projective measurements. We also design a quantum circuit to measure the two
components of the error and disturbance.


title:
Observability of Heavy Charged Higgs through s-channel Single Top Events
  at LHC

abstract:
  The charged Higgs bosons can be produced as a resonance in s-channel single
top events. The light charged Higgs in such events preferably decays to a pair
of $\tau \nu$ thus making it difficult to distinguish from the large single W
events producing the same final state. However, the heavy charged Higgs decay
to a pair of $t \bar{b}$ can be extracted from the SM background events. The
final state under consideration in this paper contains the top quark decay to
$W^+ b$ followed by $W^+$ decay to electrons or muons. It is shown that this
signal can be observed at LHC at a large area of MSSM phase space ($m(H^+),
tan\beta$). Finally $5\sigma$ and 95% CL exclusion contours are presented at
different integrated luminosities of LHC assuming a nominal center of mass
energy of $\sqrt{s}$ = 14 TeV.


title:
First-principles studies of the structural, electronic, and optical
  properties of a novel thorium compound Rb2Th7Se15

abstract:
  The structural, electronic, and optical properties of a recently synthesized
thorium compound Rb2Th7Se15 have been calculated in the density functional
theory framework for the first time. The calculated direct band gap was 1.471
eV (generalized gradient approximation) and 1.171 eV (local density
approximation), with both results being close to the experimental result of
1.83 eV. High covalency/iconicity of the Th-Se/Rb-Se bonds was demonstrated by
calculating effective Mulliken charges of all ions. The polarized calculations
of the complex dielectric function are presented; dependence of the calculated
index of refraction was fitted to the Sellmeyer equation in the wavelength
range from 500 to 2500 nm.


title: Searching for a preferred direction with Union2.1 data

abstract:
  A cosmological preferred direction was reported from the type Ia supernovae
(SNe Ia) data in recent years. We use the Union2.1 data to give a simple
classification of such studies for the first time. Because the maximum
anisotropic direction is independent of isotropic dark energy models, we adopt
two cosmological models ($\Lambda$CDM, $w$CDM) for the hemisphere comparison
analysis and $\Lambda$CDM model for dipole fit approach. In hemisphere
comparison method, the matter density and the equation of state of dark energy
are adopted as the diagnostic qualities in the $\Lambda$CDM model and $w$CDM
model, respectively. In dipole fit approach, we fit the fluctuation of distance
modulus. We find that there is a null signal for the hemisphere comparison
method, while a preferred direction ($b=-14.3^\circ \pm 10.1^\circ,
l=307.1^\circ \pm 16.2^\circ$) for the dipole fit method. This result indicates
that the dipole fit is more sensitive than the hemisphere comparison method.


title: Interacting Viscous Dark Energy in Bianchi Type-I Universe

abstract:
  A solution to the coincidence and Big Rip problems on the bases of an
anisotropic space-time is proposed. To do so, we study the interaction between
viscous dark energy and dark matter in the scope of the Bianchi type-I
Universe. We parameterize the viscosity and the interaction between the two
fluids by constants $\zeta_{0}$ and $\sigma$ respectively. A detailed
investigation on the cosmological implications of this parametrization has been
made. We have also performed a geometrical diagnostic by using the statefinder
pairs $\{s, r\}$ and $\{q, r\}$ in order to differentiate between different
dark energy models. Moreover, we fit the coupling parameter $\sigma$ as well as
the Hubble's parameter $H_{0}$ of our model by minimizing the $\chi^{2}$
through the age differential method, involving a direct measurement of $H$.


title: The gonality and the Clifford index of curves on a toric surface

abstract:
  We determine the gonality and the Clifford index for curves on a compact
smooth toric surface. Moreover, it is shown that their gonality are computed by
pencils on the ambient surface. From the geometrical view point, this means
that the gonality can be read off from the lattice polygon associated to the
curve.


title: Designing Fe Nanostructures at Graphene/h-BN Interfaces

abstract:
  Tailor-made magnetic nanostructures offer a variety of functionalities useful
for technological applications. In this work, we explore the possibilities of
realizing Fe nanostructures at the interfaces of 2D graphene and h-BN by ab
initio density functional calculations. With the aid of ab initio
Born-Oppenheimer molecular dynamics simulations and diffusion barriers
calculated by nudged elastic band method, we find that (i) diffusion barriers
of Fe on BN are much smaller than those on graphene, (ii) the Fe adatoms form
clusters within a short time interval (~2.1 ps) and (iii) Fe clusters diffuse
easily across the C-N interface but become immobile at the C-B interface. The
calculated magnetic exchange coupling between Fe clusters at C-B interfaces
varies non-monotonically as a function of the width of BN separating the
graphene parts. One may envisage design of magnetic nanostructures at the C-B
interface of 2D graphene/h-BN hybrids to realize interesting applications
related to spintronics.


title:
Numerical study of blow-up in solutions to generalized
  Kadomtsev-Petviashvili equations

abstract:
  We present a numerical study of solutions to the generalized
Kadomtsev-Petviashvili equations with critical and supercritical nonlinearity
for localized initial data with a single minimum and single maximum. In the
cases with blow-up, we use a dynamic rescaling to identify the type of the
singularity. We present a discussion of the observed blow-up scenarios.


title:
Structural simplicity and complexity of compressed calcium: electronic
  origin

abstract:
  Simple cubic structure with one atom in the unit cell found in compressed
calcium is contrintuitive with regards to traditional view on tendency of
transition to densely packed structures on the increase of pressure. To
understand this unusual transformation it is necessary to assume electron
transfer from outer core to the valence band and increase of valence electron
number for calcium from 2 to ~3,5. This assumption is supported by the model of
the Fermi sphere - Brillouin zone interaction that increases under compression.
Recently found structure of Ca-VII with tetragonal cell containing 32 atoms
(tI32) is similar to the intermetallic compound In5Bi3 with 3,75 valence
electrons per atom. Structural relations are analyzed in regard to a
resemblance of the electronic structure. Correlations of structure and physical
properties of Ca are discussed.


title: Dark Matter 2013

abstract:
  This article reviews the status of the exciting and fastly evolving field of
dark matter research as of summer 2013, when it was discussed at ICRC 2013 in
Rio de Janeiro. It focuses on the three main avenues to detect WIMP dark
matter: direct detection, indirect detection and collider searches. The article
is based on the dark matter rapporteur talk summarizing the presentations given
at the conference, filling some gaps for completeness.


title: Characteristics of conservations laws of chiral-type systems

abstract:
  In this note a new way to construct the characteristics of conservations laws
of integrable chiral-type systems is proposed.


title: Semi-equivelar maps on the surface of Euler characteristic -1

abstract:
  Semi-Equivelar maps are generalizations of Archimedean solids to the surfaces
other than 2-sphere. In earlier work a complete classification of
semi-equivelar map of type $(3^5, 4)$ on the surface of Euler characteristic -1
was given. In the meantime Karabas an Nedela classified vertex transitive
semi-equivelar maps on the double torus. In this article we study the types of
semi-equivelar maps on double torus that are also available on the surface of
Euler characteristic -1. We classify them and show that none of them are vertex
transitive.


title:
Multi criteria decision making approach for selecting effort estimation
  model

abstract:
  Effort Estimation has always been a challenging task for the Project
managers. Many researchers have tried to help them by creating different types
of models. This has been already proved that none is successful for all types
of projects and every type of environment. Analytic Hierarchy Process has been
identified as the tool that would help in Multi Criteria Decision Making.
Researchers have identified that Analytic Hierarchy Process can be used for the
comparison of effort estimation of different models and techniques. But the
problem with traditional Analytic Hierarchy Process is its inability to deal
with the imprecision and subjectivity in the pairwise comparison process. The
motive of this paper is to propose Fuzzy Analytic Hierarchy Process, which can
be used to rectify the subjectivity and imprecision of Analytic Hierarchy
Process and can be used for selecting the type of Model best suited for
estimating the effort for a given problem type or environment. Instead of
single crisp value, Fuzzy Analytic Hierarchy Process uses a range of values to
incorporate decision maker uncertainty. From this range, decision maker can
select the value that reflects his confidence and also he can specify his
attitude like optimistic, pessimistic or moderate. In this work, the comparison
of Analytic Hierarchy Process and Fuzzy Analytic Hierarchy Process is concluded
using a case study of selection of effort estimation model.


title: Soft computing techniques for software effort estimation

abstract:
  The effort invested in a software project is probably one of the most
important and most analyzed variables in recent years in the process of project
management. The limitation of algorithmic effort prediction models is their
inability to cope with uncertainties and imprecision surrounding software
projects at the early development stage. More recently attention has turned to
a variety of machine learning methods, and soft computing in particular to
predict software development effort. Soft computing is a consortium of
methodologies centering in fuzzy logic, artificial neural networks, and
evolutionary computation. It is important, to mention here, that these
methodologies are complementary and synergistic, rather than competitive. They
provide in one form or another flexible information processing capability for
handling real life ambiguous situations. These methodologies are currently used
for reliable and accurate estimate of software development effort, which has
always been a challenge for both the software industry and academia. The aim of
this study is to analyze soft computing techniques in the existing models and
to provide in depth review of software and project estimation techniques
existing in industry and literature based on the different test datasets along
with their strength and weaknesses


title: Effect of data preprocessing on software effort estimation

abstract:
  Software effort estimation requires high accuracy, but accurate estimations
are difficult to achieve. Increasingly, data mining is used to improve an
organization's software process quality, e. g. the accuracy of effort
estimations . There are a large number of different method combination exists
for software effort estimation, selecting the most suitable combination becomes
the subject of research in this paper. In this study, three simple
preprocessors are taken (none, norm, log) and effort is measured using COCOMO
model. Then results obtained from different preprocessors are compared and norm
preprocessor proves to be more accurate as compared to other preprocessors.


title:
Fourier coefficients of GL(N) automorphic forms in arithmetic
  progressions

abstract:
  We show that the multiple divisor functions of integers in invertible residue
classes modulo a prime number, as well as the Fourier coefficients of GL(N)
Maass cusp forms for all N larger than 2, satisfy a central limit theorem in a
suitable range, generalizing the case N=2 treated by E. Fouvry, S. Ganguly, E.
Kowalski and P. Michel. Such universal Gaussian behaviour relies on a deep
equidistribution result of products of hyper-Kloosterman sums.


title:
Off-shell effects on the interaction of Nambu-Goldstone bosons and $D$
  mesons

abstract:
  The Bethe-Salpeter equation in unitarized chiral perturbation theory is
usually solved with the so-called on-shell approximation. The underlying
argument is that the off-shell effects can be absorbed by the corresponding
coupling constants and physical masses, which has been corroborated by the
success of unitarized chiral perturbation theory in describing a variety of
physical phenomena. Such an approximation needs to be scrutinized when applied
to study the light-quark mass evolution of physical observables, as routinely
performed nowadays. In the present work, we propose to solve the Bethe-Salpeter
equation with the full off-shell terms of the chiral potentials and apply this
formalism to the description of the latest $n_f=2+1$ lattice QCD (LQCD) data on
the scattering lengths of Nambu-Goldstone bosons off $D$ mesons. It is shown
that the LQCD data can be better described in this formalism than in the widely
used on-shell approximation. On the other hand, no qualitative difference
between the on-shell and off-shell approaches is observed for the light-quark
mass evolution of the scattering lengths, given the limited LQCD data and their
relatively large uncertainties. We also show that the light-quark mass
dependence of the $D^*_{s0}(2317)$ remains essentially the same in both
approaches.


title:
Generalized Extended Hamming Codes over Galois Ring of Characteristic
  $2^{n}$

abstract:
  In this paper, we introduce generalized extended Hamming codes over Galois
rings $GR(2^n,m)$ of characteristic $2^n$ with extension degree $m$.
Furthermore we prove that the minimum Hamming weight of generalized extended
Hamming codes over $GR(2^n,m)$ is 4 and the minimum Lee weight of generalized
extended Hamming codes over $GR(8,m)$ is 6 for all $m \geq 3$.


title: Time-optimal control of SU(2) quantum operations

abstract:
  We propose an analysis of the time-optimal control of SU(2) quantum
operations. By using the Pontryagin Maximum Principle, we show how to determine
the optimal trajectory reaching a given target state. Explicit analytical
solutions are given for two specific examples. We discuss the role of the
detuning in the construction of the optimal synthesis.


title: Reformulating the Kriging Algorithm to the Practicing Miner

abstract:
  The main aim of applied geostatistics is to derive `mean' and `variance' of
ore to the practicing miner. This paper suggests brand-new approach to the
problem.


title:
Superstructures of Cubic and Hexagonal Diamonds Comprising a Family of
  Novel $sp^3$ Superhard Carbon Allotropes

abstract:
  Superstructures of cubic and hexagonal diamonds (h- and c-diamond) comprising
a family of stable diamond-like $sp^3$ hybridized novel carbon allotropes are
proposed, which are referred to as U$_n$-carbon where $n \geq 2$ denotes the
number of structural layers in a unit cell. The conventional h- and c-diamond
are included in this family as members with $n=2$ and 3, respectively.
U$_n$-carbon ($n=4-6$), which are unveiled energetically and thermodynamically
more stable than h-diamond and possess remarkable kinetic stabilities, are
shown to be insulators with indirect gaps of $5.6 \sim 5.8$ eV, densities of $
3.5 \sim 3.6$ g/cm$^3$, bulk modulus of $4.3 \sim 4.4 \times 10^{2}$ GPa, and
Vickers hardness of $92.9 \sim 97.5$ GPa even harder than h- and c-diamond. The
simulated x-ray diffraction and Raman spectra are presented for experimental
characterization. These new structures of carbon would have a compelling impact
in physics, chemistry, materials science and geophysics.


title:
Eigenvalues and eigenfunctions of the anharmonic oscillator
  $V(x,y)=x^{2}y^{2}$

abstract:
  We obtain sufficiently accurate eigenvalues and eigenfunctions for the
anharmonic oscillator with potential $V(x,y)=x^{2}y^{2}$ by means of three
different methods. Our results strongly suggest that the spectrum of this
oscillator is discrete in agreement with early rigorous mathematical proofs and
against a recent statement that cast doubts about it.


title:
Prefix and plain Kolmogorov complexity characterizations of
  2-randomness: simple proofs

abstract:
  Joseph Miller [16] and independently Andre Nies, Frank Stephan and Sebastiaan
Terwijn [18] gave a complexity characterization of 2-random sequences in terms
of plain Kolmogorov complexity C: they are sequences that have infinitely many
initial segments with O(1)-maximal plain complexity (among the strings of the
same length). Later Miller [17] showed that prefix complexity K can also be
used in a similar way: a sequence is 2-random if and only if it has infinitely
many initial segments with O(1)-maximal prefix complexity (which is n + K (n)
for strings of length n). The known proofs of these results are quite involved;
in this paper we provide simple direct proofs for both of them.
  In [16] Miller also gave a quantitative version of the first result: the
0'-randomness deficiency of a sequence {\omega} equals lim inf [n - C
({\omega}1 . . . {\omega}n)] + O(1). (Our simplified proof can also be used to
prove this.) We show (and this seems to be a new result) that a similar
quantitative result is also true for prefix complexity: 0'-randomness
deficiency equals lim inf [n + K (n) -- K ({\omega}1 . . . {\omega}n)] + O(1).


title: Fault Tolerant Synthesis of Reversible Circuits

abstract:
  Reversible computing has emerged as a possible low cost alternative to
conventional computing in terms of speed, power consumption and computing
capability. In order to achieve reliable circuits in reversible computing,
provision for fault tolerance is necessary. A number of fault models, fault
tolerant techniques (such as parity-preserving) and testing approaches have
proposed in literature. This dissertation exploits parity-preserving
characteristics of two reversible gates which provide low cost
parity-preserving based fault tolerance. In order to extend online testability
of reversible circuits, the substitution of Peres gate has been presented. The
online testing capabilities of MCF including Swap and Fredkin gates were also
identifies. Finally a tool was developed to implement all above substitutions
and converting any reversible circuit to parity-preserving based fault tolerant
circuit.


title: Voltage interval mappings for an elliptic bursting model

abstract:
  We employed Poincar\'e return mappings for a parameter interval to an
exemplary elliptic bursting model, the FitzHugh-Nagumo-Rinzel model.
  Using the interval mappings, we were able to examine in detail the
bifurcations that underlie the complex activity transitions between: tonic
spiking and bursting, bursting and mixed-mode oscillations, and finally,
mixed-mode oscillations and quiescence in the FitzHugh-Nagumo-Rinzel model. We
illustrate the wealth of information, qualitative and quantitative, that was
derived from the Poincar\'e mappings, for the neuronal models and for similar
(electro)chemical systems.


title: Showcase of Blue Sky Catastrophes

abstract:
  Let a system of differential equations possess a saddle-node periodic orbit
such that every orbit in its unstable manifold is homoclinic, i.e. the unstable
manifold is a subset of the (global) stable manifold. We study several
bifurcation cases where the splitting of such a homoclinic connection causes
the Blue Sky Catastrophe, including the onset of complex dynamics. The birth of
an invariant torus or a Klein bottle is also described.


title: A Critical Assessment of the Boltzmann Approach for Active Systems

abstract:
  Generic models of propelled particle systems posit that the emergence of
polar order is driven by the competition between local alignment and noise.
Although this notion has been confirmed employing the Boltzmann equation, the
range of applicability of this equation remains elusive. We introduce a broad
class of mesoscopic collision rules and analyze the prerequisites for the
emergence of polar order in the framework of kinetic theory. Our findings
suggest that a Boltzmann approach is appropriate for weakly aligning systems
but is incompatible with experiments on cluster forming systems.


title:
HERMES at Mercator, competitive high-resolution spectroscopy with a
  small telescope

abstract:
  HERMES, a fibre-fed high-resolution (R=85000) echelle spectrograph with good
stability and excellent throughput, is the work-horse instrument of the 1.2-m
Mercator telescope on La Palma. HERMES targets building up time series of
high-quality data of variable stellar phenomena, mainly for asteroseismology
and binary-evolution research. In this paper we present the HERMES project and
discuss the instrument design, performance, and a future upgrade. We also
present some results of the first four years of HERMES observations. We
illustrate the value of small telescopes, equipped with efficient
instrumentation, for high-resolution spectroscopy.


title: The Hodge group and endomorphism algebra of an Abelian variety

abstract:
  This is an English translation of the author's 1981 note in Russian,
published in a Yaroslavl collection. We prove that if an Abelian variety over C
has no nontrivial endomorphisms, then its Hodge group is Q-simple.


title:
Sex-specific recombination rates and allele frequencies affect the
  invasion of sexually antagonistic variation on autosomes

abstract:
  The introduction and persistence of novel sexually antagonistic alleles can
depend upon factors that differ between males and females. Understanding the
conditions for invasion in a two-locus model can elucidate these processes. For
instance, selection can act differently upon the sexes, or sex-linkage can
facilitate the invasion of genetic variation with opposing fitness effects
between the sexes. Two factors that deserve further attention are recombination
rates and allele frequencies -- both of which can vary substantially between
the sexes. We find that sex-specific recombination rates in a two-locus diploid
model can affect the invasion outcome of sexually antagonistic alleles and that
the sex-averaged recombination rate is not necessarily sufficient to predict
invasion. We confirm that the range of permissible recombination rates is
smaller in the sex benefitting from invasion and larger in the sex harmed by
invasion. However, within the invasion space, male recombination rate can be
greater than, equal to, or less than female recombination rate in order for a
male-benefit, female-detriment allele to invade (and similarly for a
female-benefit, male-detriment allele). We further show that a novel, sexually
antagonistic allele that is also associated with a lowered recombination rate
can invade more easily when present in the double heterozygote genotype.
Finally, we find that sexual dimorphism in resident allele frequencies can
impact the invasion of new sexually antagonistic alleles at a second locus. Our
results suggest that accounting for sex-specific recombination rates and allele
frequencies can determine the difference between invasion and non-invasion of
novel sexually antagonistic alleles in a two-locus model.


title: 'Bs --> Ds l nu' near zero recoil in and beyond the Standard Model

abstract:
  We compute the normalization of the form factor entering the Bs --> Ds l nu
decay amplitude by using numerical simulations of QCD on the lattice. From our
study with Nf=2 dynamical light quarks, and by employing the maximally twisted
Wilson quark action, we obtain in the continuum limit G(1) = 1.052(46). We also
compute the scalar and tensor form factors in the region near zero recoil and
find f0(t0)/f+(t0)=0.77(2), fT(t0,mb)/f+(t0)=1.08(7), for t0=11.5 GeV^2. These
latter results are useful for searching the effects of physics beyond the
Standard Model in Bs --> Ds l nu decays. Our results for the similar form
factors relevant to the non-strange case indicate that the method employed here
can be used to achieve the precision determination of the B --> D l nu decay
amplitude as well.


title:
Controlled assembly of graphene sheets and nanotubes: fabrication of
  suspended multi-element all-carbon vibrational structures

abstract:
  We report on the fabrication and operation of a multi-element vibrational
structure consisting of two graphene mechanical resonators coupled by a
nanotube beam. The whole structure is suspended. Each graphene resonator is
clamped by two metal electrodes. The structure is fabricated using a
combination of electron-beam lithography and atomic-force microscopy
nano-manipulation. This layout allows us to detect the mechanical vibrations
electrically. The measured eigenmodes are localized in either one of the
graphene resonators. The coupling due to the nanotube is studied by measuring
the shift of the resonance frequency of one graphene resonator as a function of
the vibration amplitude of the other resonator. Coupled graphene resonators
hold promise for the study of nonlinear dynamics, the manipulation of
mechanical states, and quantum non-demolition measurements.


title: Complete Mixed Doubles Round Robin Tournaments

abstract:
  We present a new type of tournament design that we call a complete mixed
doubles round robin tournament, CMDRR(n,k), that generalizes spouse-avoiding
mixed doubles round robin tournaments and strict Mitchell mixed doubles round
robin tournaments. We show that CMDRR(n,k) exist for all allowed values of n
and k apart from 4 exceptions and 31 possible exceptions. We show that a fully
resolvable CMDRR(2n,0) exists for all n $\ge$ 5 and a fully resolvable
CMDRR(3n,n) exists for all n $\ge$ 5 and n odd. We prove a product theorem for
constructing CMDRR(n,k).


title: Some Residually Solvable One-Relator Groups

abstract:
  This communication records some observations made in the course of studying
one-relator groups from the point of view of residual solvability. As a
contribution to clas- sification efforts we single out some relator types that
render the corresponding one-relator groups residually solvable.


title: Groups and Semigroups Defined by Colorings of Synchronizing Automata

abstract:
  In this paper we combine the algebraic properties of Mealy machines
generating self-similar groups and the combinatorial properties of the
corresponding deterministic finite automata (DFA). In particular, we relate
bounded automata to finitely generated synchronizing automata and characterize
finite automata groups in terms of nilpotency of the corresponding DFA.
Moreover, we present a decidable sufficient condition to have free semigroups
in an automaton group. A series of examples and applications is widely
discussed, in particular we show a way to color the De Bruijn automata into
Mealy automata whose associated semigroups are free, and we present some
structural results related to the associated groups.


title:
Composite Bound States and Broken U(1) symmetry in the Chemical Master
  Equation derivation of the Gray-Scott Model

abstract:
  We give a first principles derivation of the stochastic partial differential
equations that describe the chemical reactions of the Gray-Scott model (GS):
$U+2V {\stackrel {\lambda}{\rightarrow}} 3 V;$ and $V {\stackrel
{\mu}{\rightarrow}} P$, $U {\stackrel {\nu}{\rightarrow}} Q$, with a constant
feed rate for $U$. We find that the conservation of probability ensured by the
chemical master equation leads to a modification of the usual differential
equations for the GS model which now involves two composite fields and also
intrinsic noise terms. One of the composites is $\psi_1 = \phi_v^2$, where $ <
\phi_v >_{\eta} = v$ is the concentration of the species $V$ and the averaging
is over the internal noise $\eta_{u,v,\psi_1}$. The second composite field is
the product of three fields $ \chi = \lambda \phi_u \phi_v^2$ and requires a
noise source to ensure probability conservation. A third composite $\psi_2 =
\phi_{u} \phi_{v}$ can be also be identified from the noise-induced reactions.
The Hamiltonian that governs the time evolution of the many-body wave function,
associated with the master equation, has a broken U(1) symmetry related to
particle number conservation. By expanding around the (broken symmetry) zero
energy solution of the Hamiltonian (by performing a Doi shift) one obtains from
our path integral formulation the usual reaction diffusion equation, at the
classical level. The Langevin equations that are derived from the chemical
master equation have multiplicative noise sources for the density fields
$\phi_u, \phi_v, \chi$ that induce higher order processes such as $n
\rightarrow n$ scattering for $n > 3$. The amplitude of the noise acting on $
\phi_v$ is itself stochastic in nature.


title:
New bounds for the discrete Fourier restriction to the sphere in four
  and five dimensions

abstract:
  We improve the range for the discrete Fourier restriction to the four and
five dimensional spheres. We rely on two new ingredients, incidence theory and
Siegel's mass formula.


title:
The Discrete and Semi-continuous Fr\'echet Distance with Shortcuts via
  Approximate Distance Counting and Selection Techniques

abstract:
  The \emph{Fr\'echet distance} is a well studied similarity measures between
curves. The \emph{discrete Fr\'echet distance} is an analogous similarity
measure, defined for a sequence $A$ of $m$ points and a sequence $B$ of $n$
points, where the points are usually sampled from input curves. In this paper
we consider a variant, called the \emph{discrete Fr\'echet distance with
shortcuts}, which captures the similarity between (sampled) curves in the
presence of outliers. For the \emph{two-sided} case, where shortcuts are
allowed in both curves, we give an $O((m^{2/3}n^{2/3}+m+n)\log^3 (m+n))$-time
algorithm for computing this distance. When shortcuts are allowed only in one
noise-containing curve, we give an even faster randomized algorithm that runs
in $O((m+n)^{6/5+\varepsilon})$ expected time, for any $\varepsilon>0$.
  Our techniques are novel and may find further applications. One of the main
new technical results is: Given two sets of points $A$ and $B$ and an interval
$I$, we develop an algorithm that decides whether the number of pairs $(x,y)\in
A\times B$ whose distance ${\rm dist}(x,y)$ is in $I$, is less than some given
threshold $L$. The running time of this algorithm decreases as $L$ increases.
In case there are more than $L$ pairs of points whose distance is in $I$, we
can get a small sample of pairs that contains a pair at approximate median
distance (i.e., we can approximately "bisect" $I$). We combine this procedure
with additional ideas to search, with a small overhead, for the optimal
one-sided Fr\'echet distance with shortcuts, using a very fast decision
procedure. We also show how to apply this technique for approximating distance
selection (with respect to rank), and for computing the semi-continuous
Fr\'echet distance with one-sided shortcuts.


title: The Post correspondence problem in groups

abstract:
  We generalize the classical Post correspondence problem ($\mathbf{PCP}_n$)
and its non-homogeneous variation ($\mathbf{GPCP}_n$) to non-commutative groups
and study the computational complexity of these new problems. We observe that
$\mathbf{PCP}_n$ is closely related to the equalizer problem in groups, while
$\mathbf{GPCP}_n$ is connected to the double twisted conjugacy problem for
endomorphisms. Furthermore, it is shown that one of the strongest forms of the
word problem in a group $G$ (we call it the {\em hereditary word problem}) can
be reduced to $\mathbf{GPCP}_n$ in $G$ in polynomial time.
  The main results are that $\mathbf{PCP}_n$ is decidable in a finitely
generated nilpotent group in polynomial time, while $\mathbf{GPCP}_n$ is
undecidable in any group containing free non-abelian subgroup (though the
argument is very different from the classical case of free semigroups). We show
that the double endomorphism twisted conjugacy problem is undecidable in free
groups of sufficiently large finite rank. We also consider the bounded
$\mathbf{PCP}$ and observe that it is in $\mathbf{NP}$ for any group with
$\mathbf{P}$-time decidable word problem, meanwhile it is $\mathbf{NP}$-hard in
any group containing free non-abelian subgroup. In particular, the bounded
$\mathbf{PCP}$ is $\mathbf{NP}$-complete in non-elementary hyperbolic groups
and non-abelian right angle Artin groups.


title: Superconductivity and magnetism on flux grown single crystals of NiBi3

abstract:
  We present resistivity, magnetization and specific heat measurements on flux
grown single crystals of NiBi3. We find typical behavior of a type-II
superconductor, with, however, a sizable magnetic signal in the superconducting
phase. There is a hysteretic magnetization characteristic of a ferromagnetic
compound. By following the magnetization as a function of temperature, we find
a drop at temperatures corresponding to the Curie temperature of ferromagnetic
amorphous Ni. Thus, we assign the magnetism in NiBi$_3$ crystals to amorphous
Ni impurities.


title: Probing many-body interactions in an optical lattice clock

abstract:
  We present a unifying theoretical framework that describes recently observed
many-body effects during the interrogation of an optical lattice clock operated
with thousands of fermionic alkaline earth atoms. The framework is based on a
many-body master equation that accounts for the interplay between elastic and
inelastic p-wave and s-wave interactions, finite temperature effects and
excitation inhomogeneity during the quantum dynamics of the interrogated atoms.
Solutions of the master equation in different parameter regimes are presented
and compared. It is shown that a general solution can be obtained by using the
so called Truncated Wigner Approximation which is applied in our case in the
context of an open quantum system. We use the developed framework to model the
density shift and decay of the fringes observed during Ramsey spectroscopy in
the JILA 87Sr and NIST 171Yb optical lattice clocks. The developed framework
opens a suitable path for dealing with a variety of strongly-correlated and
driven open-quantum spin systems.


title: Graph-Based Approaches to Clustering Network-Constrained Trajectory Data

abstract:
  Clustering trajectory data attracted considerable attention in the last few
years. Most of prior work assumed that moving objects can move freely in an
euclidean space and did not consider the eventual presence of an underlying
road network and its influence on evaluating the similarity between
trajectories. In this paper, we present an approach to clustering such
network-constrained trajectory data. More precisely we aim at discovering
groups of road segments that are often travelled by the same trajectories. To
achieve this end, we model the interactions between segments w.r.t. their
similarity as a weighted graph to which we apply a community detection
algorithm to discover meaningful clusters. We showcase our proposition through
experimental results obtained on synthetic datasets.


title:
Easy scalar decompositions for efficient scalar multiplication on
  elliptic curves and genus 2 Jacobians

abstract:
  The first step in elliptic curve scalar multiplication algorithms based on
scalar decompositions using efficient endomorphisms-including
Gallant-Lambert-Vanstone (GLV) and Galbraith-Lin-Scott (GLS) multiplication, as
well as higher-dimensional and higher-genus constructions-is to produce a short
basis of a certain integer lattice involving the eigenvalues of the
endomorphisms. The shorter the basis vectors, the shorter the decomposed scalar
coefficients, and the faster the resulting scalar multiplication. Typically,
knowledge of the eigenvalues allows us to write down a long basis, which we
then reduce using the Euclidean algorithm, Gauss reduction, LLL, or even a more
specialized algorithm. In this work, we use elementary facts about quadratic
rings to immediately write down a short basis of the lattice for the GLV, GLS,
GLV+GLS, and Q-curve constructions on elliptic curves, and for genus 2 real
multiplication constructions. We do not pretend that this represents a
significant optimization in scalar multiplication, since the lattice reduction
step is always an offline precomputation---but it does give a better insight
into the structure of scalar decompositions. In any case, it is always more
convenient to use a ready-made short basis than it is to compute a new one.


title: Sparsity-Promoting Sensor Selection for Non-linear Measurement Models

abstract:
  Sensor selection is an important design problem in large-scale sensor
networks. Sensor selection can be interpreted as the problem of selecting the
best subset of sensors that guarantees a certain estimation performance. We
focus on observations that are related to a general non-linear model. The
proposed framework is valid as long as the observations are independent, and
its likelihood satisfies the regularity conditions. We use several functions of
the Cram\'er-Rao bound (CRB) as a performance measure. We formulate the sensor
selection problem as the design of a selection vector, which in its original
form is a nonconvex l0-(quasi) norm optimization problem. We present relaxed
sensor selection solvers that can be efficiently solved in polynomial time. We
also propose a projected subgradient algorithm that is attractive for
large-scale problems and also show how the algorithm can be easily distributed.
The proposed framework is illustrated with a number of examples related to
sensor placement design for localization.


title: Direct numerical simulation of the dynamics of sliding rough surfaces

abstract:
  The noise generated by the friction of two rough surfaces under weak contact
pressure is usually called roughness noise. The underlying vibration which
produces the noise stems from numerous instantaneous shocks (in the microsecond
range) between surface micro-asperities. The numerical simulation of this
problem using classical mechanics requires a fine discretization in both space
and time. This is why the finite element method takes much CPU time. In this
study, we propose an alternative numerical approach which is based on a
truncated modal decomposition of the vibration, a central difference
integration scheme and two algorithms for contact: The penalty algorithm and
the Lagrange multiplier algorithm. Not only does it reproduce the empirical
laws of vibration level versus roughness and sliding speed found experimentally
but it also provides the statistical properties of local events which are not
accessible by experiment. The CPU time reduction is typically a factor of 10.


title:
Stability properties for quasilinear parabolic equations with measure
  data and applications

abstract:
  Let $\Omega$ be a bounded domain of $\mathbb{R}^{N}$, and $Q=\Omega
\times(0,T).$ We first study the problem \[ \left\{ \begin{array} [c]{l}%
{u_{t}}-{\Delta_{p}}u=\mu\qquad\text{in }Q,\\ {u}=0\qquad\text{on
}\partial\Omega\times(0,T),\\ u(0)=u_{0}\qquad\text{in }\Omega, \end{array}
\right. \] where $p>1$, $\mu\in\mathcal{M}_{b}(\Omega)$ and $u_{0}\in
L^{1}(\Omega).$ Our main result is a \textit{stability theorem }extending the
results of Dal Maso, Murat, Orsina, Prignet, for the elliptic case\textit{. }
As an application, we consider the perturbed problem\textit{ } \[ \left\{
\begin{array} [c]{l}% {u_{t}}-{\Delta_{p}}u+\mathcal{G}(u)=\mu\qquad\text{in
}Q,\\ {u}=0\qquad\text{on }\partial\Omega\times(0,T),\\
u(0)=u_{0}\qquad\text{in }\Omega, \end{array} \right. \] where $\mathcal{G}(u)$
may be an absorption or a source term$.$ In the model case
$\mathcal{G}(u)=\pm\left\vert u\right\vert ^{q-1}u$ $(q>p-1),$ or $\mathcal{G}$
has an exponential type. We give existence results when $q$ is subcritical, or
when the measure $\mu$ is good in time and satisfies suitable capacity
conditions.


title: Real Time Data Warehouse

abstract:
  Data Warehouse (DW) is an essential part of Business Intelligence. DW emerged
as a fast growing reporting and analysis technique in early 1980s. Today, it
has almost replaced relational databases. However, with passage of time, static
and historic data of DWs could not produce Real Time reporting and analysis,
thus giving a way to emerge the Idea of Real Time Data Warehouse (RTDW).
Although, there are problems with RTDWs, but with advancement in technology and
researchers focus, RTDWs will be able to generate real time reports, analysis
and forecasting.


title:
Efficient and Robust Allocation Algorithms in Clouds under Memory
  Constraints

abstract:
  We consider robust resource allocation of services in Clouds. More
specifically, we consider the case of a large public or private Cloud platform
that runs a relatively small set of large and independent services. These
services are characterized by their demand along several dimensions (CPU,
memory,...) and by their quality of service requirements, that have been
defined through an SLA in the case of a public Cloud or fixed by the
administrator in the case of a private Cloud. This quality of service defines
the required robustness of the service, by setting an upper limit on the
probability that the provider fails to allocate the required quantity of
resources. This maximum probability of failure can be transparently turned into
a pair (price,penalty). Failures can indeed hit the platform, and resilience is
provided through service replication. Our contribution is two-fold. First, we
propose a resource allocation strategy whose complexity is logarithmic in the
number of resources, what makes it very efficient for large platforms. Second,
we propose an efficient algorithm based on rare events detection techniques in
order to estimate the robustness of an allocation, a problem that has been
proven to be P-complete. Finally, we provide an analysis of the proposed
strategy through an extensive set of simulations, both in terms of the overall
number of allocated resources and in terms of time necessary to compute the
allocation.


title:
On a conjecture on sparse binomial-type polynomials by Brown, Dilcher
  and Manna

abstract:
  We prove a conjecture by Brown, Dilcher and Manna on the asymptotic behavior
of sparse binomial-type polynomials arising naturally in a graph theoretical
context in connection with the expected number of independent sets of a graph.


title:
Joint temporal and contemporaneous aggregation of random-coefficient
  AR(1) processes

abstract:
  We discuss joint temporal and contemporaneous aggregation of $N$ independent
copies of AR(1) process with random-coefficient $a \in [0,1)$ when $N$ and time
scale $n$ increase at different rate. Assuming that $a$ has a density,
regularly varying at $a = 1$ with exponent $-1 < \beta < 1$, different joint
limits of normalized aggregated partial sums are shown to exist when
$N^{1/(1+\beta)}/n$ tends to (i) $\infty$, (ii) 0, (iii) $0 < \mu < \infty$.
The limit process arising under (iii) admits a Poisson integral representation
on $(0,\infty) \times C(\mathbb{R})$ and enjoys "intermediate" properties
between fractional Brownian motion limit in (i) and sub-Gaussian limit in (ii).


title: Lattice study of the Schwinger model at fixed topology

abstract:
  At small lattice spacing QCD simulations are expected to become stuck in a
single topological sector. Observables evaluated in a fixed topological sector
differ from their counterparts in full QCD, i.e. at unfixed topology, by volume
dependent corrections. We investigate these corrections in the two-flavor
Schwinger model, which is in several aspects similar to QCD, using Wilson
fermions. We also try to remove these corrections by suitable extrapolations to
infinite volume.


title:
Stochastic Resonance and Dynamic First-Order Pseudo-Phase Transitions in
  the Irreversible Growth of Thin Films under Spatially Periodic Magnetic
  Fields

abstract:
  We study the irreversible growth of magnetic thin films under the influence
of spatially periodic fields by means of extensive Monte Carlo simulations. We
find first-order pseudo-phase transitions that separate a dynamically
disordered phase from a dynamically ordered phase. By analogy with
time-dependent oscillating fields applied to Ising-type models, we
qualitatively associate this dynamic transition with the
localization/delocalization transition of "spatial hysteresis" loops. Depending
on the relative width of the magnetic film, $L$, compared to the wavelength of
the external field, $\lambda$, different transition regimes are observed. For
small systems ($L<\lambda$), the transition is associated with the Standard
Stochastic Resonance regime, while, for large systems ($L>\lambda$), the
transition is driven by Anomalous Stochastic Resonance. The origin of the
latter is identified as due to the emergence of an additional relevant
lengthscale, namely the roughness of the spin domain switching interface. The
distinction between different stochastic resonance regimes is discussed at
length, both qualitatively by means of snapshot configurations, as well as
quantitatively via residence-length and order-parameter probability
distributions.


title:
Limit properties of exceedances point processes of scaled stationary
  Gaussian sequences

abstract:
  We derive the limiting distributions of exceedances point processes of
randomly scaled weakly dependent stationary Gaussian sequences under some mild
asymptotic conditions. In the literature analogous results are available only
for contracted stationary Gaussian sequences. In this paper, we include
additionally the case of randomly inflated stationary Gaussian sequences with a
Weibullian type random scaling. It turns out that the maxima and minima of both
contracted and inflated weakly dependent stationary Gaussian sequences are
asymptotically independent.


title: On types of matrices and centralizers of matrices and permutations

abstract:
  It is known that that the centralizer of a matrix over a finite field
depends, up to conjugacy, only on the type of the matrix, in the sense defined
by J. A. Green. In this paper an analogue of the type invariant is defined that
in general captures more information; using this invariant the result on
centralizers is extended to arbitrary fields. The converse is also proved: thus
two matrices have conjugate centralizers if and only if they have the same
generalized type. The paper ends with the analogous results for symmetric and
alternating groups.


title:
Embedding binary sequences into Bernoulli site percolation on
  $\mathbb{Z}^3$

abstract:
  We investigate the problem of embedding infinite binary sequences into
Bernoulli site percolation on $\mathbb{Z}^d$ with parameter $p$, known also as
percolation of words.\ In 1995, I.\ Benjamini and H.\ Kesten proved that, for
$d \geq 10$ and $p=1/2$, all sequences can be embedded, almost surely. They
conjectured that the same should hold for $d \geq 3$. In this paper we consider
$d \geq 3$ and $p \in (p_c(d), 1-p_c(d))$, where $p_c(d)<1/2$ is the critical
threshold for site percolation on $\mathbb{Z}^d$. We show that there exists an
integer $M = M (p)$, such that, a.s., every binary sequence, for which every
run of consecutive {0s} or {1s} contains at least $M$ digits, can be embedded.


title:
Dislocation mutual interactions mediated by mobile impurities and the
  conditions for plastic instabilities

abstract:
  Matallic alloys, such as Al or Cu, or mild steel, display plastic
instabilities in a well defined range of temperatures and deformation rates, a
phenomenon known as the Portevin-Le Chatelelier (PLC) effect. The stick-slip
behavior, or serration, typical of this effect is due to the discontinuous
motion of dislocations as they interact with solute atoms. Here we study a
simple model of interacting dislocations and show how the classical Einstein
fluctuation-dissipation relation can be used to define the temperature in a
range of model parameters and to construct a phase diagram of serration that
can be compared to experimental results. Furthermore, performing analytical
calculations and numerically integrating the equations of motion, we clarify
the crucial role played by dislocation mutual interactions in serration.


title: "Stellar Prominences" on OB stars to explain wind-line variability

abstract:
  Many O and B stars show unexplained cyclical variability in their winds, i.e.
modulation of absorption features on the rotational timescale, but not strictly
periodic over longer timescales. For these stars no dipolar magnetic fields
have been detected, with upper limits below 300 G. Similar cyclical variability
is also found in many optical lines, which are formed at the base of the wind.
We propose that these cyclical variations are caused by the presence of
multiple, transient, short-lived, corotating magnetic loops, which we call
"stellar prominences". We present a simplified model representing these
prominences to explain the cyclical optical wind-line variability in the O
supergiant lambda Cephei. Other supporting evidence for such prominences comes
from the recent discovery of photometric variability in a comparable O star,
which was explained by the presence of multiple transient bright spots,
presumably of magnetic origin as well.


title:
Stokes IQUV mapping of $\alpha^2$ CVn & other Ap stars using ESPaDOnS
  and NARVAL

abstract:
  New spectral line polarisation observations of 7 bright Ap stars have been
obtained with the ESPaDOnS and Narval high resolution spectropolarimeters
(Silvester et al. 2012). The aim of this data set is produce a series of
surface magnetic field and surface chemistry maps for these Ap stars. We
present new magnetic maps for the Ap star $\alpha^2$ CVn using these new data
and the MDI inversion code INVERS10. $\alpha^2$ CVn is the first Ap star to be
observed during two separate epochs using high resolution phase resolved
spectropolarimetric $IQUV$ observations and as such allows us an insight into
how stable the surface magnetic structure is over a decade timescale. We show
that the new maps give a magnetic field structure consistent with the previous
maps obtained by Kochukhov and Wade (2010) from lower quality MuSiCoS spectra
taken a decade ago and that the field topology cannot be described by a dipolar
or quadrupolar field.


title: A Clue To Magnetic Activity Occurring On Near-Contact Binary V1003 Her

abstract:
  Taking into account results obtained from models and analyses, we determined
the nature and structures of V1003 Her. We analysed the light curves obtained
in this study together with the available radial velocity curve. The analysis
revealed that the inclination (i) of the system was found to be 45.82 (2.71),
while the semi-major axis (a) was computed as 2.925 (0.143) Rsun. The mass of
the primary component was found to be 1.204 (0.004) Msun, while it was obtained
as 0.450 (0.006) Msun for the secondary component. The radius of the primary
component was computed as 1.424 (0.001) Rsun, while it was computed as 0.904
(0.001) Rsun for the secondary component. The analysis indicates that there are
two spotted areas close to each other on the surface of the secondary
component. In addition, B-band light and B-V colour curves reveal that there is
a radiation excess toward the phase of 0.40. This should be caused due to some
heating of the surface by the events like thermal flare, or the structures like
plage. Finally, the analysis and model demonstrated that V1003 Her should be a
near-contact binary with high level


title: Variational Methods and Planar Elliptic Growth

abstract:
  A nested family of growing or shrinking planar domains is called a Laplacian
growth process if the normal velocity of each domain's boundary is proportional
to the gradient of the domain's Green function with a fixed singularity on the
interior. In this paper we review the Laplacian growth model and its key
underlying assumptions, so that we may consider a generalization to so-called
elliptic growth, wherein the Green function is replaced with that of a more
general elliptic operator--this models, for example, inhomogeneities in the
underlying plane. In this paper we continue the development of the underlying
mathematics for elliptic growth, considering perturbations of the Green
function due to those of the driving operator, deriving characterizations and
examples of growth, developing a weak formulation of growth via balayage, and
discussing of a couple of inverse problems in the spirit of Calder\'on. We
conclude with a derivation of a more delicate, reregularized model for
Hele-Shaw flow.


title: From Webs to Polylogarithms

abstract:
  We compute a class of diagrams contributing to the multi-leg soft anomalous
dimension through three loops, by renormalizing a product of semi-infinite
non-lightlike Wilson lines in dimensional regularization. Using non-Abelian
exponentiation we directly compute contributions to the exponent in terms of
webs. We develop a general strategy to compute webs with multiple gluon
exchanges between Wilson lines in configuration space, and explore their
analytic structure in terms of $\alpha_{ij}$, the exponential of the Minkowski
cusp angle formed between the lines $i$ and $j$. We show that beyond the
obvious inversion symmetry $\alpha_{ij}\to 1/\alpha_{ij}$, at the level of the
symbol the result also admits a crossing symmetry $\alpha_{ij}\to
-\alpha_{ij}$, relating spacelike and timelike kinematics, and hence argue that
in this class of webs the symbol alphabet is restricted to $\alpha_{ij}$ and
$1-\alpha_{ij}^2$. We carry out the calculation up to three gluons connecting
four Wilson lines, finding that the contributions to the soft anomalous
dimension are remarkably simple: they involve pure functions of uniform weight,
which are written as a sum of products of polylogarithms, each depending on a
single cusp angle. We conjecture that this type of factorization extends to all
multiple-gluon-exchange contributions to the anomalous dimension.


title:
Bipolar spin blockade and coherent state superpositions in a triple
  quantum dot

abstract:
  Spin qubits based on interacting spins in double quantum dots have been
successfully demonstrated. Readout of the qubit state involves a conversion of
spin to charge information, universally achieved by taking advantage of a spin
blockade phenomenon resulting from Pauli's exclusion principle. The archetypal
spin blockade transport signature in double quantum dots takes the form of a
rectified current. Currently more complex spin qubit circuits including triple
quantum dots are being developed. Here we show both experimentally and
theoretically (a) that in a linear triple quantum dot circuit, the spin
blockade becomes bipolar with current strongly suppressed in both bias
directions and (b) that a new quantum coherent mechanism becomes relevant.
Within this mechanism charge is transferred non-intuitively via coherent states
from one end of the linear triple dot circuit to the other without involving
the centre site. Our results have implications in future complex
nano-spintronic circuits.


title: K-theory of weight varieties

abstract:
  Let $T$ be a compact torus and $(M,\omega)$ a Hamiltonian $T$-space. We give
a new proof of the $K$-theoretic analogue of the Kirwan surjectivity theorem in
symplectic geometry by using the equivariant version of the Kirwan map
introduced in one of R. Goldin's papers. We compute the kernel of this
equivariant Kirwan map, and hence give a computation of the kernel of the
Kirwan map. As an application, we find the presentation of the kernel of the
Kirwan map for the $T$-equivariant $K$-theory of flag varieties $G/T$ where $G$
is a compact, connected and simply-connected Lie group. In the last section, we
find explicit formulae for the $K$-theory of weight varieties.


title: Cosmogenic 7Be in ground level air in Rostov-on-Don (Russia) (2001-2011)

abstract:
  The deposition flux of cosmogenic 7Be in the industrial city Rostov-on-Don
(Russia) from 2001 to 2011 has been measured. The variations of annual 7Be
deposition flux appear to be mainly correlated with the number of the
meteorological parameters and solar activity. For the first time correlations
of the volume activity of cosmogenic 7Be with such meteorological parameters as
temperature, precipitation, wind speed, atmospheric pressure, relative humidity
are identified.


title:
Molecular branch of a small highly-elongated Fermi gas with an impurity:
  Full three-dimensional versus effective one-dimensional description

abstract:
  We consider an impurity immersed in a small Fermi gas under highly-elongated
harmonic confinement. The impurity interacts with the atoms of the Fermi gas
through an isotropic short-range potential with three-dimensional free-space
s-wave scattering length $a_{3\text{d}}$. We investigate the energies of the
molecular branch, i.e., the energies of the state that corresponds to a gas
consisting of a weakly-bound diatomic molecule and "unpaired" atoms, as a
function of the s-wave scattering length $a_{3\text{d}}$ and the ratio $\eta$
between the angular trapping frequencies in the tight and weak confinement
directions. The energies obtained from our three-dimensional description that
accounts for the dynamics in the weak and tight confinement directions are
compared with those obtained within an effective one-dimensional framework,
which accounts for the dynamics in the tight confinement direction via a
renormalized one-dimensional coupling constant. Our theoretical results are
related to recent experimental measurements.


title:
Thread-shaped intensity field after light propagation through the
  convective cell

abstract:
  A thread-shaped intensity field has been observed at 2 m distance when a
laser beam passed through a water convection cell with characteristic Rayleigh
number about 10^{8}. Similar intensity fields were simulated by using phase
screen method for various turbulent spectrum in the cell. We show that
experimental result can be described by Tatarskii spectrum which take into
account the inner scale.


title: Regularization in the Restricted Four Body Problem

abstract:
  The restricted (equilateral) four-body problem consists of three bodies of
masses m1, m2 and m3 (called primaries) lying in a Lagrangian config- uration
of the three-body problem, i,e,. they remain fixed at the apices of an
equilateral triangle in a rotating coordinate system. A massless fourth body
moves under the Newtonian gravitation law due to the three pri- maries; as in
the restricted three-body problem the fourth mass does not affect the motion of
the three primaries. In this paper we show a global regularization of binary
collisions of the infinitesimal body with two of the primaries.


title:
Polynomials and Primes in Generalized Arithmetic Progressions (Revised
  Version)

abstract:
  We provide upper bounds on the density of a symmetric generalized arithmetic
progression lacking nonzero elements of the form h(n) for natural numbers n, or
h(p) with p prime, for appropriate polynomials h with integer coefficients. The
prime variant can be interpreted as a multi-dimensional, polynomial extension
of Linnik's Theorem. This version is a revision of the published version. Most
notably, the properness hypotheses have been removed from Theorems 2 and 3, and
the numerology in Theorem 2 has been improved.