title:
Decoherence in a fermion environment: Non-Markovianity and Orthogonality
  Catastrophe

abstract:
  We analyze the non-Markovian character of the dynamics of an open two-level
atom interacting with a gas of ultra-cold fermions. In particular, we discuss
the connection between the phenomena of orthogonality catastrophe and Fermi
edge singularity occurring in such a kind of environment and the memory-keeping
effects which are displayed in the time evolution of the open system.


title:
Bolometric Corrections for optical light curves of Core-collapse
  Supernovae

abstract:
  Through the creation of spectral energy distributions for well-observed
literature core-collapse supernovae (CCSNe), we present corrections to
transform optical light curves to full bolometric light curves. These
corrections take the form of parabolic fits to optical colours, with $B - I$
and $g - r$ presented as exemplary fits, while parameters for fits to other
colours are also given. We find evolution of the corrections with colour to be
extremely homogeneous across CCSNe of all types in the majority of cases, and
also present fits for stripped-envelope and type II SNe separately. A separate
fit, appropriate for SNe exhibiting strong emission due to cooling after shock
breakout, is presented. Such a method will homogenise the creation of
bolometric light curves for CCSNe where observations cannot constrain the
emitted flux - of particular importance for current and future SN surveys where
typical follow-up of the vast majority of events will occur only in the optical
window, resulting in consistent comparisons of modelling involving bolometric
light curves. Test cases for SNe 1987A and 2009jf using the method presented
here are shown, and the bolometric light curves are recovered with excellent
accuracy in each case.


title:
Quantum phases of quadrupolar Fermi gases in coupled one-dimensional
  systems

abstract:
  Following the recent proposal to create quadrupolar gases [S.G. Bhongale et
al., Phys. Rev. Lett. 110, 155301 (2013)], we investigate what quantum phases
can be created in these systems in one dimension. We consider a geometry of two
coupled one-dimensional systems, and derive the quantum phase diagram of
ultra-cold fermionic atoms interacting via quadrupole-quadrupole interaction
within a Tomonaga-Luttinger-liquid framework. We map out the phase diagram as a
function of the distance between the two tubes and the angle between the
direction of the tubes and the quadrupolar moments. The latter can be
controlled by an external field. We show that there are two magic angles
$\theta^{c}_{B,1}$ and $\theta^{c}_{B,2}$ between $0$ to $\pi/2$, where the
intratube quadrupolar interactions vanish and change signs. Adopting a
pseudo-spin language with regards to the two 1D systems, the system undergoes a
spin-gap transition and displays a zig-zag density pattern, above
$\theta^{c}_{B,2}$ and below $\theta^{c}_{B,1}$. Between the two magic angles,
we show that polarized triplet superfluidity and a planar spin-density wave
order compete with each other. The latter corresponds to a bond order solid in
higher dimensions. We demonstrate that this order can be further stabilized by
applying a commensurate periodic potential along the tubes.


title: Stark broadening data for spectral lines of rare-earth elements: Nb III

abstract:
  The electron-impact widths for 15 doubly charged Nb ion lines have been
theoretically determined by using the modified semiempirical method. Using the
obtained results, we considered the influence of the electron-impact mechanism
on line shapes in spectra of chemically peculiar stars and white dwarfs.


title: Magnetic field of Vega

abstract:
  Recent spectropolarimetric observations of Vega have revealed a weak magnetic
field. I present here the results of spectropolarimetric study of Vega during
37 nights from 1997 to 2012


title:
Electronic, magnetic and transport properties of full and half-metallic
  thin film Heusler alloys

abstract:
  The electronic and magnetic bulk properties of half-metallic Heusler alloys
such as Co$_{2}$FeSi, Co$_{2}$FeAl, Co$_{2}$MnSi and Co$_{2}$MnAl are
investigated by means of {\em ab initio} calculations in combination with Monte
Carlo simulations. The electronic structure is analyzed using the plane wave
code Quantum Espresso and magnetic exchange interactions are determined using
the KKR method. From the magnetic exchange interactions the Curie temperature
is obtained via Monte Carlo simulations. In addition, electronic transport
properties of the trilayer systems consisting of two semi-infinite platinum
leads and a Heusler layer in between are obtained from the fully relativistic
KKR method by employing the Kubo-Greenwood formalism. The focus is on
thermoelectric properties, namely the Seebeck effect and its spin dependence.
It turns out that already thin Heusler layers provide highly polarized currents
within the systems. This is attributed to the recovery of half-metallicity with
increasing thickness. The absence of electronic states of the spin down
electrons around the Fermi level suppresses the contribution of this spin
channel to the total conductivity. This strongly influences the thermoelectric
properties of such systems and results in polarized thermoelectric currents.


title: A Search for Planetary Nebulae With the SDSS: the outer regions of M31

abstract:
  We have developed a method to identify planetary nebula (PN) candidates in
imaging data of the Sloan Digital Sky Survey (SDSS). This method exploits the
SDSS' five-band sampling of emission lines in PN spectra, which results in a
color signature distinct from that of other sources. Selection criteria based
on this signature can be applied to nearby galaxies in which PNe appear as
point sources. We applied these criteria to the whole area of M31 as scanned by
the SDSS, selecting 167 PN candidates that are located in the outer regions of
M31. The spectra of 80 selected candidates were then observed with the 2.2m
telescope at Calar Alto Observatory. These observations and cross-checks with
literature data show that our method has a selection rate efficiency of about
90%, but the efficiency is different for the different groups of PNe
candidates.
  In the outer regions of M31, PNe trace different well-known morphological
features like the Northern Spur, the NGC205 Loop, the G1 Clump, etc. In
general, the distribution of PNe in the outer region 8<R<20 kpc along the minor
axis shows the "extended disk" - a rotationally supported low surface
brightness structure with an exponential scale length of 3.21+/-0.14 kpc and a
total mass of ~10^10 M_{\sun}, which is equivalent to the mass of M33. We
report the discovery of three PN candidates with projected locations in the
center of Andromeda NE, a very low surface brightness giant stellar structure
in the outer halo of M31. Two of the PNe were spectroscopically confirmed as
genuine PNe. These two PNe are located at projected distances along the major
axis of ~48 Kpc and ~41 Kpc from the center of M31 and are the most distant PNe
in M31 found up to now.


title:
Free boundary stable hypersurfaces in manifolds with density and
  rigidity results

abstract:
  Let $M$ be a weighted manifold with boundary $\partial M$, i.e., a Riemannian
manifold where a density function is used to weight the Riemannian Hausdorff
measures. In this paper we compute the first and the second variational
formulas of the interior weighted area for deformations by hypersurfaces with
boundary in $\partial M$. As a consequence, we obtain variational
characterizations of critical points and second order minima of the weighted
area with or without a volume constraint. Moreover, in the compact case, we
obtain topological estimates and rigidity properties for free boundary stable
and area-minimizing hypersurfaces under certain curvature and boundary
assumptions on $M$. Our results and proofs extend previous ones for Riemannian
manifolds (constant densities) and for hypersurfaces with empty boundary in
weighted manifolds.


title:
Chaotic Interference and Quantum-Classical Correspondence: Mechanisms of
  Decoherence and State Mixing

abstract:
  The famous Nils Bohr's quantum-classical correspondence principle states that
the classical mechanics is a limiting case of the more general quantum
mechanics. This implies that ``under certain conditions" quantum laws of motion
become equivalent to classical laws. One of the conditions is fairly obvious:
the corresponding classical action should be very large as compared with the
Planck's constant. But this condition is not sufficient. Suppression of effects
of quantum interference ("decoherence") is the phenomenon of primary importance
for understanding of the Bohr's principle. Being, in essence, of quite general
nature, this problem takes on special significance in the case of non-linear
classically chaotic quantum systems. Whereas the rapid decay of phase
correlations is an underlying feature of the classical dynamical chaos, the
"quantum chaos" by itself is not capable of destroying the quantum phase
coherence. Strictly speaking, any initially pure quantum state remains pure
during an arbitrary long unitary evolution. Basically, formation of incoherent
mixed states (decoherence) results only from the process of preparation of a
mixed initial state or interaction with a noisy environment. Just the
decoherence brigdes the quantum and classical worlds.
  Peculiarities of the time behavior of Peres fidelity, state purity, Shanon
and von Neumann entropies are analyzed in detail. We demonstrate the ways the
decoherence shows up in periodically driven systems that can be associated with
Ramsey-type interferomentry experiments with ion traps. Finally, decoherence in
ballistic electron quantum transport caused by interaction with a disordered
environment is considered.


title: Numerical studies of ground state fidelity of the Bose-Hubbard model

abstract:
  We compute ground state fidelity of the one-dimensional Bose-Hubbard model at
unit filling factor. To this aim, we apply the DMRG algorithm to systems with
open and periodic boundary conditions. We find that fidelity differs
significantly in the two cases and study its scaling properties in the quantum
critical regime.

categories: cond-mat.str-el cond-mat.quant-gas cond-mat.stat-mech quant-ph


title: A bijection between triangulations and $312$-avoiding permutations

abstract:
  We define a bijection between triangulations of a convex polygon and
$312$-avoiding permutations through the process of "ear-clipping". This
bijection is then used to obtain a bijection between polygon dissections and a
certain class of $312$-avoiding permutations.


title: Spontaneous fission half-lives of nuclei in a phenomenological model

abstract:
  A simple phenomenological model, based on the \'Swi{\c a}tecki idea for
evaluation of the spontaneous fission half-lives is proposed. The model
contains only one adjustable parameter fixed to the data for even-even nuclei
and two additional hindrance factors to the life-times, which give the effect
of odd particles. A good agreement with the experimental data for all
fissioning nuclei is achieved.


title: Ice aggregate contacts at the nm-scale

abstract:
  Aggregation of ice particles is a fundamental process in the interstellar
medium as well as in planet formation. Dedicated to study the contact physics
of nm-ice particles we developed a thermal gradient force microscope. This
allows us and was used to measure pull-off forces with a resolution on the
nN-scale and to measure rolling. Furthermore, based on a free probe, it also
allows us to study twisting torques for the first time. The experiments show
that torques required to twist are significantly larger than that macroscopic
models scaled down to the nm-size range would predict. This implies that (ice)
aggregates in astrophysical settings with small constituents are more robust
against restructuring than previously thought. They likely grow as fractal
aggregates to larger size before they restructure and during later compact
growth they likely retain a higher porosity during further evolution towards
planetesimals.


title:
Constructing Time Series Shape Association Measures: Minkowski Distance
  and Data Standardization

abstract:
  It is surprising that last two decades many works in time series data mining
and clustering were concerned with measures of similarity of time series but
not with measures of association that can be used for measuring possible direct
and inverse relationships between time series. Inverse relationships can exist
between dynamics of prices and sell volumes, between growth patterns of
competitive companies, between well production data in oilfields, between wind
velocity and air pollution concentration etc. The paper develops a theoretical
basis for analysis and construction of time series shape association measures.
Starting from the axioms of time series shape association measures it studies
the methods of construction of measures satisfying these axioms. Several
general methods of construction of such measures suitable for measuring time
series shape similarity and shape association are proposed. Time series shape
association measures based on Minkowski distance and data standardization
methods are considered. The cosine similarity and the Pearsons correlation
coefficient are obtained as particular cases of the proposed general methods
that can be used also for construction of new association measures in data
analysis.


title: Empirical likelihood on the full parameter space

abstract:
  We extend the empirical likelihood of Owen [Ann. Statist. 18 (1990) 90-120]
by partitioning its domain into the collection of its contours and mapping the
contours through a continuous sequence of similarity transformations onto the
full parameter space. The resulting extended empirical likelihood is a natural
generalization of the original empirical likelihood to the full parameter
space; it has the same asymptotic properties and identically shaped contours as
the original empirical likelihood. It can also attain the second order accuracy
of the Bartlett corrected empirical likelihood of DiCiccio, Hall and Romano
[Ann. Statist. 19 (1991) 1053-1061]. A simple first order extended empirical
likelihood is found to be substantially more accurate than the original
empirical likelihood. It is also more accurate than available second order
empirical likelihood methods in most small sample situations and competitive in
accuracy in large sample situations. Importantly, in many one-dimensional
applications this first order extended empirical likelihood is accurate for
sample sizes as small as ten, making it a practical and reliable choice for
small sample empirical likelihood inference.


title: Detection of $D^{\pm}$ mesons production in pA-interactions at 70 GeV

abstract:
  The results of analysis SERP-E-184 experiment data, obtained with 70 GeV
proton beam irradiation of active target with carbon, silicon and lead plates
are presented. For 3-prongs charged charmed mesons decays, event selection
criteria were developed and detection efficiency was calculated with detailed
simulation using FRITIOF7.02 and GEANT3.21 programs. Signals of decays were
found and charm production inclusive cross sections estimated at near threshold
energy. The lifetimes and A-dependence of cross section were measured. Yields
of D mesons and their ratios in comparison with data of other experiments and
theoretical predictions are presented.


title:
On the Lorentzian minimal surfaces in $\mathbb E^4_1$ with finite type
  Gauss map

abstract:
  In this paper, we study the Lorentzian minimal surfaces in the Minkowski
space-time with finite type Gauss map. First, we obtain the classification of
this type of surfaces with pointwise 1-type Gauss map. Then, we proved that
there are no Lorentzian minimal surface in the Minkowski space-time with null
2-type Gauss map.


title:
On the quasi-minimal surfaces in the 4-dimensional de Sitter space with
  1-type Gauss map

abstract:
  In this paper, we study the Gauss map of the surfaces in the de Sitter
space-time $\mathbb S^4_1(1)$. First, we prove that a space-like surface lying
in the de Sitter space-time has pointwise 1-type Gauss map if and only if it
has parallel mean curvature vector. Then, we obtain the complete classification
of the quasi-minimal surfaces with 1-type Gauss map.


title:
Stochastic Master Equation Analysis of Optimized Three-Qubit
  Nondemolition Parity Measurement

abstract:
  We analyze a direct parity measurement of the state of three superconducting
qubits in circuit quantum electrodynamics. The parity is inferred from a
homodyne measurement of the reflected/transmitted microwave radiation and the
measurement is direct in the sense that the parity is measured without the need
for any quantum circuit operations or for ancilla qubits. Qubits are coupled to
two resonant cavity modes, allowing the steady state of the emitted radiation
to satisfy the necessary conditions to act as a pointer state for the parity.
However, the transient dynamics violates these conditions and we analyze this
detrimental effect and show that it can be overcome in the limit of weak
measurement signal. Our analysis shows that, with a moderate degree of
post-selection, it is possible to achieve post-measurement states with fidelity
of order 95%. We believe that this type of measurement could serve as a
benchmark for future error-correction protocols in a scalable architecture.


title:
An Introduction to Microscopic Theories for Inhomogeneous Liquids:
  Getting Started with Density Functional Theory

abstract:
  Classical density functional theory (DFT) is a statistical mechanical theory
for calculating the density profiles of the molecules in a liquid. It is widely
used, for example. to calculate the density distribution of the molecules in
the vicinity of a confining wall, the interfacial tension, the wetting
behaviour and many other properties of nonuniform liquids. DFT can however be
somewhat daunting to students entering the field, because of the many
connections to other areas of liquid-state science that are required and used
to develop the theories. Here we give an introduction to some of the key ideas,
based on a lattice-gas (Ising) model fluid. This builds on knowledge covered in
most undergraduate statistical mechanics and thermodynamics courses and so
students can quickly get to the stage of calculating density profiles, etc for
themselves. We derive a simple DFT for the lattice-gas and present some typical
results that can readily be calculated using the theory.


title:
Search for the Infrared Emission Features from Deuterated Interstellar
  Polycyclic Aromatic Hydrocarbons

abstract:
  We report the results of a search for emission features from interstellar
deuterated polycyclic aromatic hydrocarbons (PAHs) in the 4um region with the
Infrared Camera (IRC) onboard AKARI. No significant excess emission is seen in
4.3-4.7um in the spectra toward the Orion Bar and M17 after the subtraction of
line emission from the ionized gas. A small excess of emission remains at
around 4.4 and 4.65um, but the ratio of their intensity to that of the band
emission from PAHs at 3.3-3.5um is estimated as 2-3%. This is an order of
magnitude smaller than the values previously reported and also those predicted
by the model of deuterium depletion onto PAHs. Since the subtraction of the
ionized gas emission introduces an uncertainty, the deuterated PAH features are
also searched for in the reflection nebula GN 18.14.0, which does not show
emission lines from ionized gas. We obtain a similar result that excess
emission in the 4um region, if present, is about 2% of the PAH band emission in
the 3um region. The present study does not find evidence for the presence of
the large amount of deuterated PAHs that the depletion model predicts. The
results are discussed in the context of deuterium depletion in the interstellar
medium.


title:
Solving the sign problem of two flavor scalar electrodynamics at finite
  chemical potential

abstract:
  We explore two flavor scalar electrodynamics on the lattice, which has a
complex phase problem at finite chemical potential. By rewriting the action in
terms of dual variables this complex phase problem can be solved exactly. The
dual variables are link- and plaquette occupation numbers, subject to local
constraints that have to be respected by the Monte Carlo algorithm. For the
simulation we use a local update as well as the newly developed "surface worm
algorithm", which is a generalization of the Prokof'ev Svistunov worm algorithm
concept for simulating the dual representation of abelian Gauge-Higgs models on
a lattice. We assess the performance of the two algorithms, present results for
the phase diagram and discuss condensation phenomena.


title: Generalized quasidisks and conformality II

abstract:
  We introduce a weaker variant of the concept of three point property, which
is equivalent to a non-linear local connectivity condition introduced in [12],
sufficient to guarantee the extendability of a conformal map f from the unit
disk onto a domain to the entire plane as a homeomorphism of locally
exponentially integrable distortion. Sufficient conditions for extendability to
a homeomorphism of locally p-integrable distortion are also given.


title: Lattice effective field theory for nuclei from A = 4 to A = 28

abstract:
  We present an overview of the extension of Nuclear Lattice Effective Field
Theory simulations to the regime of medium-mass nuclei. We focus on the
determination of the ground-state energies of the alpha nuclei $^{16}$O,
$^{20}$Ne, $^{24}$Mg and $^{28}$Si by means of Euclidean time projection.


title: Equilibrium spin pulsars unite neutron star populations

abstract:
  Many pulsars are formed with a binary companion from which they can accrete
matter. Torque exerted by accreting matter can cause the pulsar spin to
increase or decrease, and over long times, an equilibrium spin rate is
achieved. Application of accretion theory to these systems provides a probe of
the pulsar magnetic field. We compare the large number of recent torque
measurements of accreting pulsars with a high-mass companion to the standard
model for how accretion affects the pulsar spin period. We find that many long
spin period (P > 100 s) pulsars must possess either extremely weak (B < 10^10
G) or extremely strong (B > 10^14 G) magnetic fields. We argue that the
strong-field solution is more compelling, in which case these pulsars are near
spin equilibrium. Our results provide evidence for a fundamental link between
pulsars with the slowest spin periods and strong magnetic fields around
high-mass companions and pulsars with the fastest spin periods and weak fields
around low-mass companions. The strong magnetic fields also connect our pulsars
to magnetars and strong-field isolated radio/X-ray pulsars. The strong field
and old age of our sources suggests their magnetic field penetrates into the
superconducting core of the neutron star.


title: Vacuum Stability and the Higgs Boson

abstract:
  The discovery of the Higgs boson at the LHC, and especially the determination
of its mass around 125 GeV, together with the absence of any trace of new
physics make it conceivable that we live in a metastable (but long-lived)
electroweak vacuum. I will describe the state-of-the-art calculation that leads
to this conclusion, elaborate on possible implications as well as cures of this
instability of the Higgs potential and discuss some possible lines of attack
for lattice studies of such metastability.


title: Statistical properties of 1D parametrically kicked Hamilton systems

abstract:
  We study the 1D Hamilton systems and their statistical behaviour, assuming
the initial microcanonical distribution and describing its change under a
parametric kick, which by definition means a discontinuous jump of a control
parameter of the system. Following a previous work by Papamikos and Robnik (J.
Phys. A: Math. Theor. 44 (2012) 315102) we specifically analyze the change of
the adiabatic invariant (the action) of the system under a parametric kick: A
conjecture has been put forward that the change of the action at the mean
energy always increases, which means, for the given statistical ensemble, that
the entropy in the mean increases. By means of a detailed analysis of a great
number of case studies we show that the conjecture largely is satisfied, except
if either the potential is not smooth enough, or if the energy is too close to
a stationary point of the potential (separatrix in the phase space). Very fast
changes in a time dependent system quite generally can be well described by
such a picture and by the approximation of a parametric kick, if the change of
the parameter is sufficiently fast and takes place on the time scale of less
than one oscillation period.


title: Multifractal Analysis of functions on Heisenberg and Carnot Groups

abstract:
  In this article, we investigate the pointwise behaviors of functions on the
Heisenberg group. We find wavelet characterizations for the global and local
H\"older exponents. Then we prove some a priori upper bounds for the
multifractal spectrum of all functions in a given H\"older, Sobolev or Besov
space. These upper bounds turn out to be optimal, since in all cases they are
reached by typical functions in the corresponding functional spaces. We also
explain how to adapt our proof to extend our results to Carnot groups.


title:
Hypersurfaces in $CP^2$ and $CH^2$ with two distinct principal
  curvatures

abstract:
  It is known that hypersurfaces in $CP^n$ or $CH^n$ for which the number $g$
of distinct principal curvatures satisfied $g \le 2$ must belong to a standard
list of Hopf hypersurfaces with constant principal curvatures, provided that $n
\ge 3$. In this paper, we construct a 2-parameter family of non-Hopf
hypersurfaces in $CP^2$ and $CH^2$ with $g=2$ and show that every non-Hopf
hypersurface with $g=2$ is locally of this form.


title:
Nuclear deformation and neutron excess as competing effects for pygmy
  dipole strength

abstract:
  The electromagnetic dipole strength below the neutron-separation energy has
been studied for the xenon isotopes with mass numbers A = 124, 128, 132, and
134 in nuclear resonance fluorescence experiments using the ELBE bremsstrahlung
facility at Helmholtz-Zentrum Dresden-Rossendorf and the HIgS facility at
Triangle Universities Nuclear Laboratory Durham. The systematic study gained
new information about the influence of the neutron excess as well as of nuclear
deformation on the strength in the region of the pygmy dipole resonance. The
results are compared with those obtained for the chain of molybdenum isotopes
and with predictions of a random-phase approximation in a deformed basis. It
turned out that the effect of nuclear deformation plays a minor role compared
with the one caused by neutron excess. A global parametrization of the strength
in terms of neutron and proton numbers allowed us to derive a formula capable
of predicting the summed E1 strengths in the pygmy region for a wide mass range
of nuclides.


title: Grassmannians and Koszul duality

abstract:
  Let $X$ be a partial flag variety, stratified by orbits of the Borel. We give
a criterion for the category of modular perverse sheaves to be equivalent to
modules over a Koszul ring. This implies that modular category $\mathcal O$ is
governed by a Koszul-algebra in small examples.


title: On the Number of Edges of Fan-Crossing Free Graphs

abstract:
  A graph drawn in the plane with n vertices is k-fan-crossing free for k > 1
if there are no k+1 edges $g,e_1,...e_k$, such that $e_1,e_2,...e_k$ have a
common endpoint and $g$ crosses all $e_i$. We prove a tight bound of 4n-8 on
the maximum number of edges of a 2-fan-crossing free graph, and a tight 4n-9
bound for a straight-edge drawing. For k > 2, we prove an upper bound of
3(k-1)(n-2) edges. We also discuss generalizations to monotone graph
properties.


title: Spatially extended OH+ emission from the Orion Bar and Ridge

abstract:
  We report the first detection of a Galactic source of OH+ line emission: the
Orion Bar, a bright nearby photon-dominated region. Line emission is detected
over ~1' (0.12 pc), tracing the Bar itself as well as the Southern tip of the
Orion Ridge. The line width of ~4 km/s suggests an origin of the OH+ emission
close to the PDR surface, at a depth of A_V ~0.3-0.5 into the cloud where most
hydrogen is in atomic form. Steady-state collisional and radiative excitation
models require unrealistically high OH+ column densities to match the observed
line intensity, indicating that the formation of OH+ in the Bar is rapid enough
to influence its excitation. Our best-fit OH+ column density of ~1x10^14 cm^-2
is similar to that in previous absorption line studies, while our limits on the
ratios of OH+/H2O+ (>~40) and OH+/H3O+ (>~15) are higher than seen before.
  The column density of OH+ is consistent with estimates from a thermo-chemical
model for parameters applicable to the Orion Bar, given the current
uncertainties in the local gas pressure and the spectral shape of the ionizing
radiation field. The unusually high OH+/H2O+ and OH+/H3O+ ratios are probably
due to the high UV radiation field and electron density in this object. In the
Bar, photodissociation and electron recombination are more effective destroyers
of OH+ than the reaction with H2, which limits the production of H2O+. The
appearance of the OH+ lines in emission is the result of the high density of
electrons and H atoms in the Orion Bar, since for these species, inelastic
collisions with OH+ are faster than reactive ones. In addition, chemical
pumping, far-infrared pumping by local dust, and near-UV pumping by Trapezium
starlight contribute to the OH+ excitation. Similar conditions may apply to
extragalactic nuclei where OH+ lines are seen in emission.


title: Locating Star-Forming Regions in Quasar Host Galaxies

abstract:
  We present a study of the morphology and intensity of star formation in the
host galaxies of eight Palomar-Green quasars using observations with the Hubble
Space Telescope. Our observations are motivated by recent evidence for a close
relationship between black hole growth and the stellar mass evolution in its
host galaxy. We use narrow-band [O II] $\lambda$3727, H$\beta$, [O III]
$\lambda$5007 and Pa$\alpha$ images, taken with the WFPC2 and NICMOS
instruments, to map the morphology of line-emitting regions, and, after
extinction corrections, diagnose the excitation mechanism and infer
star-formation rates. Significant challenges in this type of work are the
separation of the quasar light from the stellar continuum and the
quasar-excited gas from the star-forming regions. To this end, we present a
novel technique for image decomposition and subtraction of quasar light. Our
primary result is the detection of extended line-emitting regions with sizes
ranging from 0.5 to 5 kpc and distributed symmetrically around the nucleus,
powered primarily by star formation. We determine star-formation rates of order
a few tens of M$_\odot$/yr. The host galaxies of our target quasars have
stellar masses of order $10^{11}$ M$_\odot$ and specific star formation rates
on a par with those of M82 and luminous infrared galaxies. As such they fall at
the upper envelope or just above the star-formation mass sequence in the
specific star formation vs stellar mass diagram. We see a clear trend of
increasing star formation rate with quasar luminosity, reinforcing the link
between the growth of the stellar mass of the host and the black hole mass
found by other authors.


title:
Ultra long spin decoherence times in graphene quantum dots with a small
  number of nuclear spins

abstract:
  We study the dynamics of an electron spin in a graphene quantum dot, which is
interacting with a bath of less than ten nuclear spins via the anisotropic
hyperfine interaction. Due to substantial progress in the fabrication of
graphene quantum dots, the consideration of such a small number of nuclear
spins is experimentally relevant. This choice allows us to use exact
diagonalization to calculate the longtime average of the electron spin as well
as its decoherence time. We investigate the dependence of spin observables on
the initial states of nuclear spins and on the position of nuclear spins in the
quantum dot. Moreover, we analyze the effects of the anisotropy of the
hyperfine interaction for different orientations of the spin quantization axis
with respect to the graphene plane. Interestingly, we then predict remarkable
long decoherence times of more than 10ms in the limit of few nuclear spins.


title: Factorization of exclusive electroinduced two-nucleon knockout

abstract:
  We investigate the factorization properties of the exclusive electroinduced
two-nucleon knockout reaction $A(e,e'pN)$. A factorized expression for the
cross section is derived and the conditions for factorization are studied. The
$A(e,e'pN)$ cross section is shown to be proportional to the conditional
center-of-mass (c.m.) momentum distribution for close-proximity pairs in a
state with zero relative orbital momentum and zero radial quantum number. The
width of this conditional c.m. momentum distribution is larger than the one
corresponding with the full c.m. momentum distribution. It is shown that the
final-state interactions (FSIs) only moderately affect the shape of the
factorization function for the $A(e,e'pN)$ cross sections. Another prediction
of the proposed factorization is that the mass dependence of the $A(e,e'pp)$
$[A(e,e'pn)]$ cross sections is much softer than $\frac{Z(Z-1)}{2}$ $[NZ]$.


title:
A space-time covariance function for spatio-temporal random processes
  and spatio-temporal prediction (kriging)

abstract:
  We consider a stationary spatio-temporal random process and assume that we
have a sample. By defining a sequence of discrete Fourier transforms at
canonical frequencies at each location, and using these complex valued random
varables as observed sample, we obtain expressions for the spatio-temporal
covariance functions and the spectral density functions of the spatio-temporal
random processes. These spectra correspond to non separable class of random
processes. The spatio-temporal covariance functions, obtained here are
functions of the spatial distance and the temporal frequency and are similar to
Matern class. These are in terms of modified Bessel functions of the second
kind. and the parameters are in terms of the second order spectral density
functions of the random proces and the spatial distances. We consider the
estimation of the parameters of the covariance function and also briefly
mention their asymptotic properties. The estimation of the entire data at a
known location, and also the estimation of a value given the above sample is
also considered. The predictors are obtained using the vectors of Discrete
Fourier Transforms. We also describe a statistical test for testing the
independence of the m spatial time series (testing for spatial independence)
using the Finite Fourier Transforms and it is based on the likelihood ratio
test of complex valued random variables The methods are illustrated with real
data.
  Keywords: Discrete Fourier Transforms, Covariance functions, Spectral density
functions, Space-Time Processses, Prediction(kriging) Laplacian operators,
Frequency Variogram, Tests for independence, Whittle likelihood.


title: Efficient saturation of an ion in free space

abstract:
  We report on the demonstration of a light-matter interface coupling light to
a single $^{174}\textrm{Yb}^+$ ion in free space. The interface is realized
through a parabolic mirror partially surrounding the ion. It transforms a
Laguerre-Gaussian beam into a linear dipole wave converging at the mirror's
focus. By measuring the non-linear response of the atomic transition we deduce
the power required for reaching an upper-level population of $1/4$ to be
$692\pm20~\textrm{pW}$ at half linewidth detuning from the atomic resonance.
Performing this measurement while scanning the ion through the focus provides a
map of the focal intensity distribution. From the measured power we infer a
coupling efficiency of $7.2\pm0.2~\%$ on the linear dipole transition when
illuminating from half solid angle, being among the best coupling efficiencies
reported for a single atom in free space.


title:
Strong tip-sample coupling in thermal radiation scanning tunneling
  microscopy

abstract:
  We analyze how a probing particle modifies the infrared electromagnetic near
field of a sample. The particle, described by electric and magnetic
polarizabilities, represents the tip of an apertureless scanning optical
near-field microscope (SNOM). We show that the interaction with the sample can
be accounted for by ascribing to the particle dressed polarizabilities that
combine the effects of image dipoles with retardation. When calculated from
these polarizabilities, the SNOM signal depends only on the fields without the
perturbing tip. If the studied surface is not illuminated by an external source
but heated instead, the signal is closely related to the projected
electromagnetic local density of states (EM-LDOS). Our calculations provide the
link between the measured far-field spectra and the sample's optical
properties.We also analyze the case where the probing particle is hotter than
the sample and evaluate the impact of the dressed polarizabilities on
near-field radiative heat transfer. We show that such a heated probe above a
surface performs a surface spectroscopy, in the sense that the spectrum of the
heat current is closely related to the local electromagnetic density of states.
The calculations agree well with available experimental data.


title:
Magnetic Properties of RFe2Si2 and R(Fe1-xMx)2Si2 Systems (R=La, Y and
  Lu, M= Ni, Mn and Cu)

abstract:
  Due to the similarity to BaFe2As2 and SrFe2As2 the RFe2Si2 (R=La, Y and Lu)
system has been proposed as a potential candidate for a new superconducting
family containing Fe-Si layers as a structural unit. Various R(Fe1-xMx)2Si2
M=Ni, Mn and Cu) materials were synthesized and measured for their magnetic
properties. None of these materials is superconducting down to 5 K. Fe in
RFe2Si2 is paramagnetic. A pronounced peak at 232 K was observed in the
magnetization curve of YFe2Si2. 57Fe M\"ossbauer studies confirm the absence of
any magnetic ordering at low temperatures. Similar peaks at various
temperatures also appear in R(Fe1-xMx)2Si2 samples. Four independent factors
affect the peak position and shift it to lower temperatures: (i) the lattice
parameters, (ii) the concentration of x, (iii) the applied magnetic field, and
(iv) the magnetic nature of M. The peak position is dramatically affected by
the magnetic Mn dopants. It is propose that the magnetic peaks observed in
RFe2Si2 and in R(Fe1-xMx)2Si2 represent a new nearly ferromagnetic Fermi liquid
(NFFL) system and their nature is yet to be determined.


title:
Null holomorphic curves in $\mathbb C^3$ and the conformal Calabi-Yau
  problem

abstract:
  In this paper we survey some recent contributions by the authors to the
theory of null holomorphic curves in the complex Euclidean space $\mathbb C^3$,
as well as their applications to null holomorphic curves in the special linear
group $SL_2(\mathbb C)$, minimal surfaces in the Euclidean space $\mathbb R^3$,
and constant mean curvature one surfaces (Bryant surfaces) in the hyperbolic
3-space $\mathbb H^3$. The paper is an expanded version of the lecture given by
the second named author at the Abel Symposium in Trondheim, Norway, in July
2013.


title: Temperature response of the polarizable SWM4-NDP water model

abstract:
  Introduction of polarizability in classical molecular simulations holds the
promise to increase accuracy as well as prediction power to computer modeling.
To introduce polarizability in a straight-forward way one strategy is based on
Drude particles: dummy atoms whose displacements mimic polarizability. In this
work, molecular dynamics simulations of SWM4-NDP, a Drude-based water model,
were performed for a wide range of temperatures going from 170 K to 340 K. We
found that the density maximum is located far down in the supercooled region at
around 200 K, roughly 80 K below the experimental value. Very long relaxation
times together with a new increase in the density were found at even lower
temperatures. On the other hand, both hydrogen-bond coordination up to the
second solvation shell and tetrahedral order resembled very much what was found
for TIP4P/2005, a very good performer at the reproduction of the density curve
and other properties of bulk water in temperature space. Such a discrepancy
between the density curve and the hydrogen bond propensity was not observed in
other conventional water models. Our results suggest that while the simplicity
of the SWM4 model is appealing, its current parametrization needs improvements
in order to correctly reproduce water behavior beyond ambient conditions.


title:
Laplacian coefficients of unicyclic graphs with the number of leaves and
  girth

abstract:
  Let $G$ be a graph of order $n$ and let $\mathcal{L}(G,\lambda)=\sum_{k=0}^n
(-1)^{k}c_{k}(G)\lambda^{n-k}$ be the characteristic polynomial of its
Laplacian matrix. Motivated by Ili\'{c} and Ili\'{c}'s conjecture [A. Ili\'{c},
M. Ili\'{c}, Laplacian coefficients of trees with given number of leaves or
vertices of degree two, Linear Algebra and its Applications
431(2009)2195-2202.] on all extremal graphs which minimize all the Laplacian
coefficients in the set $\mathcal{U}_{n,l}$ of all $n$-vertex unicyclic graphs
with the number of leaves $l$, we investigate properties of the minimal
elements in the partial set $(\mathcal{U}_{n,l}^g, \preceq)$ of the Laplacian
coefficients, where $\mathcal{U}_{n,l}^g$ denote the set of $n$-vertex
unicyclic graphs with the number of leaves $l$ and girth $g$. These results are
used to disprove their conjecture. Moreover, the graphs with minimum
Laplacian-like energy in $\mathcal{U}_{n,l}^g$ are also studied.


title: Frobenius vectors, Hilbert series and gluings

abstract:
  Let $S_1$ and $S_2$ be two affine semigroups and let $S$ be the gluing of
$S_1$ and $S_2$. Several invariants of $S$ are then related to those of $S_1$
and $S_2$; we review some of the most important properties preserved under
gluings. The aim of this paper is to prove that this is the case for the
Frobenius vector and the Hilbert series. Applications to complete intersection
affine semigroups are also given.


title:
Ab-initio self-consistent Gorkov-Green's function calculations of
  semi-magic nuclei - II. Numerical implementation at second order with a
  two-nucleon interaction

abstract:
  The newly developed Gorkov-Green's function approach represents a promising
path to the ab initio description of medium-mass open-shell nuclei. We discuss
the implementation of the method at second order with a two-body interaction,
with particular attention to the numerical solution of Gorkov's equation.
Different sources of theoretical error and degrees of self-consistency are
investigated. We show that Krylov projection techniques with a multi-pivot
Lanczos algorithm efficiently handle the growth of poles in the one-body
Green's function when Gorkov's equation is solved self-consistently. The end
result is a tractable, accurate and gently scaling ab initio scheme applicable
to full isotopic chains in the medium-mass region.


title: Field Theory in the Imaginary-time Formulation

abstract:
  The imaginary-time formulation is investigated in the field theory. The Dirac
and photon's Lagrangians are treated in the imaginary-time and space and are
invariant under scale transformations, which are motivated by the
Tolman-Ehrenfest relation and Wilson's approach in the renormalization group.
With the functional approaches, the propagators of leptons and photons can be
derived both for the real- and the imaginary-time. The theory is free of UV
divergence in the integration range of the imaginary-time, $(0,\beta\,]$, which
is required by the KMS condition. The results of one-loop radiative corrections
are proved to be consistent with those in QED. The renormalization group
equations with respect to vacuum's temperature give no Landau pole and show
identical renormalization coefficients as those from the $\overline{MS}$ scheme
of the renormalization in the limit of zero temperature.


title:
Limitations of long term stability in a coherent population trapping Cs
  clock

abstract:
  Vapor cell atomic clocks exhibit reduced frequency stability for averaging
time between about one hundred and a few thousand seconds. Here we report a
study on the impact of the main parameters on the mid-to-long term instability
of a buffer-gas vapor cell Cs clock, based on coherent population trapping
(CPT). The CPT signal is observed on the Cs D1 line transmission, using a
double $\Lambda$ scheme and a Ramsey interrogation technique. The effects on
the clock frequency of the magnetic field, the cell temperature, and the laser
intensities are reported. We show in particular that the laser intensity shift
is temperature dependent. Along with the laser intensity ratio and laser
polarization properties, this is one of the most important parameters.


title:
Sequencing and characterisation of rearrangements in three S.
  pastorianus strains reveals the presence of chimeric genes and gives evidence
  of breakpoint reuse

abstract:
  Gross chromosomal rearrangements have the potential to be evolutionarily
advantageous to an adapting organism. The generation of a hybrid species
increases opportunity for recombination by bringing together two homologous
genomes. We sought to define the location of genomic rearrangements in three
strains of Saccharomyces pastorianus, a natural lager-brewing yeast hybrid of
Saccharomyces cerevisiae and Saccharomyces eubayanus, using whole genome
shotgun sequencing. Each strain of S. pastorianus has lost species-specific
portions of its genome and has undergone extensive recombination, producing
chimeric chromosomes. We predicted 30 breakpoints that we confirmed at the
single nucleotide level by designing species-specific primers that flank each
breakpoint, and then sequencing the PCR product. These rearrangements are the
result of recombination between areas of homology between the two subgenomes,
rather than repetitive elements such as transposons or tRNAs. Interestingly,
28/30 S. cerevisiae- S. eubayanus recombination breakpoints are located within
genic regions, generating chimeric genes. Furthermore we show evidence for the
reuse of two breakpoints, located in HSP82 and KEM1, in strains of proposed
independent origin.


title: A Catalogue of Temperatures for Kepler Eclipsing Binary Stars

abstract:
  We have combined the Kepler Eclipsing Binary Catalogue with information from
the HES, KIS and 2MASS photometric surveys to produce spectral energy
distribution fits to over 2600 eclipsing binaries in the catalogue over a
wavelength range of 0.36 to 2.16\AA. We present primary ($T_1$) and secondary
($T_2$) stellar temperatures, plus information on the stellar radii and system
distance ratios. The derived temperatures are on average accurate to 370K in
$T_1$ and 620K in $T_2$. Our results improve on the similarly derived physical
parameters of the Kepler Input Catalogue through consideration of both stars of
the binary system rather than a single star model, and inclusion of additional
U band photometry. We expect these results to aid future uses of the Kepler
Eclipsing Binary data, both in target selection and to inform users of the
extremely high precision light curves available. We do not include surface
gravities or system metallicities, as these were found to have an insignificant
effect on the observed photometric bands.


title:
Drawing complete multipartite graphs on the plane with restrictions on
  crossings

abstract:
  We introduce the concept of NIC-planar graphs and present the full
characterization of NIC-planar complete k-partite graphs.


title:
Integrated CARS Source based on Seeded Four-wave Mixing in Silicon
  Nitride

abstract:
  We present a theoretical investigation of an integrated nonlinear light
source for coherent anti-Stokes Raman scattering (CARS) based on silicon
nitride waveguides. Wavelength tunable and temporally synchronized signal and
idler pulses are obtained by using seeded four-wave mixing. We find that the
calculated input pump power needed for nonlinear wavelength generation is more
than one order of magnitude lower than in previously reported approaches based
on optical fibers. The tuning range of the wavelength conversion was calculated
to be 1418 nm to 1518 nm (idler) and 788 nm to 857 nm (signal), which
corresponds to a coverage of vibrational transitions from 2350 cm$^{-1}$ to
2810 cm$^{-1}$. A maximum conversion efficiency of 19.1% at a peak pump power
of 300 W was obtained.


title: Plasticity of a colloidal polycrystal under cyclic shear

abstract:
  We use confocal microscopy and time-resolved light scattering to investigate
plasticity in a col- loidal polycrystal, following the evolution of the network
of grain boundaries as the sample is submitted to thousands of shear
deformation cycles. The grain boundary motion is found to be ballistic, with a
velocity distribution function exhibiting non-trivial power law tails. The
shear- induced dynamics initially slow down, similarly to the aging of the
spontaneous dynamics in glassy materials, but eventually reach a steady state.
Surprisingly, the cross-over time between the ini- tial aging regime and the
steady state decreases with increasing probed length scale, hinting at a
hierarchical organization of the grain boundary dynamics.


title: The ABJM Model is a Higher Gauge Theory

abstract:
  M2-branes couple to a 3-form potential, which suggests that their description
involves a non-abelian 2-gerbe or, equivalently, a principal 3-bundle. We show
that current M2-brane models fit this expectation: they can be reformulated as
higher gauge theories on such categorified bundles. We thus add to the still
very sparse list of physically interesting higher gauge theories.


title: Comptonization signatures in the prompt emission of Gamma Ray Bursts

abstract:
  We report results of a systematic study of the broad--band (2--2000 keV)
time--resolved prompt emission spectra of a sample of Gamma-Ray Bursts (GRBs)
detected with both the Wide Field Cameras (WFCs) aboard the BeppoSAX satellite
and the BATSE experiment aboard CGRO. The main goal of the paper is to test
spectral models of the GRB prompt emission that have recently been proposed. In
particular, we test the photospheric model proposed by Ryde and Pe'er (2009),
i.e., blackbody plus power--law, the addition of a blackbody emission to the
Band function in the cases in which this function does not fit the data, and
the Comptonization model developed by Titarchuk et al. (2012). By considering
the few spectra for which the simple Band function does not provide a fully
acceptable fit to the data (Frontera et al. 2012), only in one case we find a
statistically significant better fit by adding a blackbody to this function. We
confirm the results found fitting the BATSE spectra alone with a blackbody plus
a power law. Instead when the BATSE GRB spectra are joined to those obtained
with WFCs (2--28 keV), this model becomes unacceptable in most of time
intervals in which we subdivide the GRB light curves. We find instead that the
Comptonization model is always acceptable, even in the few cases in which the
Band function is inconsistent with the data. We discuss the implications of
these results.


title: Smooth Embeddings for the Suzuki and Ree Curves

abstract:
  The Hermitian, Suzuki and Ree curves form three special families of curves
with unique properties. They arise as the Deligne-Lusztig varieties of
dimension one and their automorphism groups are the algebraic groups of type
2A2, 2B2 and 2G2, respectively. For the Hermitian and Suzuki curves very ample
divisors are known that yield smooth projective embeddings of the curves. In
this paper we establish a very ample divisor for the Ree curves. Moreover, for
all three families of curves we find a symmetric set of equations for a smooth
projective model, in dimensions 2, 4 and 13, respectively. Using the smooth
model we determine the unknown nongaps in the Weierstrass semigroup for a
rational point on the Ree curve.


title: Tightness of the recentered maximum of log-correlated Gaussian fields

abstract:
  We consider a family of centered Gaussian fields on the d-dimensional unit
box, whose covariance decreases logarithmically in the distance between points.
We prove tightness of the recentered maximum of the Gaussian fields and provide
exponentially decaying bounds on the right and left tails. We then apply this
result to a version of the two-dimensional continuous Gaussian free field.


title: Regularity theory for nonlinear systems of SPDEs

abstract:
  We consider systems of stochastic evolutionary equations of the type
$$du=\mathrm{div}\,S(\nabla u)\,dt+\Phi(u)dW_t$$ where $S$ is a non-linear
operator, for instance the $p$-Laplacian $$S(\xi)=(1+|\xi|)^{p-2}\xi,\quad
\xi\in\mathbb R^{d\times D},$$ with $p\in(1,\infty)$ and $\Phi$ grows linearly.
We extend known results about the deterministic problem to the stochastic
situation. First we verify the natural regularity: $$\mathbb
E\bigg[\sup_{t\in(0,T)}\int_{G'}|\nabla u(t)|^2\,dx+\int_0^T\int_{G'}|\nabla
F(\nabla u)|^2\,dx\,dt\bigg]<\infty,$$ where
$F(\xi)=(1+|\xi|)^{\frac{p-2}{2}}\xi$. If we have Uhlenbeck-structure then
$\mathbb E\big[\|\nabla u\|_q^q\big]$ is finite for all $q<\infty$.


title: Multivariate distributions with fixed marginals and correlations

abstract:
  Consider the problem of drawing random variates $(X_1,\ldots,X_n)$ from a
distribution where the marginal of each $X_i$ is specified, as well as the
correlation between every pair $X_i$ and $X_j$. For given marginals, the
Fr\'echet-Hoeffding bounds put a lower and upper bound on the correlation
between $X_i$ and $X_j$. Any achievable correlation between $X_i$ and $X_j$ is
a convex combinations of these bounds. The value $\lambda(X_i,X_j) \in [0,1]$
of this convex combination is called here the convexity parameter of
$(X_i,X_j),$ with $\lambda(X_i,X_j) = 1$ corresponding to the upper bound and
maximal correlation. For given marginal distributions functions
$F_1,\ldots,F_n$ of $(X_1,\ldots,X_n)$ we show that $\lambda(X_i,X_j) =
\lambda_{ij}$ if and only if there exist symmetric Bernoulli random variables
$(B_1,\ldots,B_n)$ (that is $\{0,1\}$ random variables with mean 1/2) such that
$\lambda(B_i,B_j) = \lambda_{ij}$. In addition, we characterize completely the
set of convexity parameters for symmetric Bernoulli marginals in two, three and
four dimensions.


title:
Threshold Saturation for Nonbinary SC-LDPC Codes on the Binary Erasure
  Channel

abstract:
  We analyze the asymptotic performance of nonbinary spatially-coupled
low-density parity-check (SC-LDPC) code ensembles defined over the general
linear group on the binary erasure channel. In particular, we prove threshold
saturation of belief propagation decoding to the so called potential threshold,
using the proof technique based on potential functions introduced by Yedla
\textit{et al.}, assuming that the potential function exists. We rewrite the
density evolution of nonbinary SC-LDPC codes in an equivalent vector recursion
form which is suited for the use of the potential function. We then discuss the
existence of the potential function for the general case of vector recursions
defined by multivariate polynomials, and give a method to construct it. We
define a potential function in a slightly more general form than one by Yedla
\textit{et al.}, in order to make the technique based on potential functions
applicable to the case of nonbinary LDPC codes. We show that the potential
function exists if a solution to a carefully designed system of linear
equations exists. Furthermore, we show numerically the existence of a solution
to the system of linear equations for a large number of nonbinary LDPC code
ensembles, which allows us to define their potential function and thus prove
threshold saturation.


title:
Bootstrap kernel for organic low dimensional systems; PPV, pentacene and
  picene

abstract:
  We apply the bootstrap kernel within time dependent density functional theory
to study one-dimensional chain of organic polymer poly-phenylene-vinylene and
molecular crystals of picene and pentacene. The behaviour of this kernel in the
presence and absence of local field effects is studied. The absorption spectra
of poly-phenylene-vinylene has a bound excitonic peak which is well reproduced
by the bootstrap kernel. Pentacene and picene, electronically similar
materials, have remarkably different excitonic physics which is also captured
properly by the bootstrap kernel. Inclusion of local-field effects dramatically
change the spectra for both picene and pentacene. We highlight the reason
behind this change. This also sheds light on the reasons behind the discrepancy
in results between two different previous Bethe-Salpeter calculations.


title: Entropy and sampling numbers of classes of ridge functions

abstract:
  We study properties of ridge functions $f(x)=g(a\cdot x)$ in high dimensions
$d$ from the viewpoint of approximation theory. The considered function classes
consist of ridge functions such that the profile $g$ is a member of a
univariate Lipschitz class with smoothness $\alpha > 0$ (including infinite
smoothness), and the ridge direction $a$ has $p$-norm $\|a\|_p \leq 1$. First,
we investigate entropy numbers in order to quantify the compactness of these
ridge function classes in $L_{\infty}$. We show that they are essentially as
compact as the class of univariate Lipschitz functions. Second, we examine
sampling numbers and face two extreme cases. In case $p=2$, sampling ridge
functions on the Euclidean unit ball faces the curse of dimensionality. It is
thus as difficult as sampling general multivariate Lipschitz functions, a
result in sharp contrast to the result on entropy numbers. When we additionally
assume that all feasible profiles have a first derivative uniformly bounded
away from zero in the origin, then the complexity of sampling ridge functions
reduces drastically to the complexity of sampling univariate Lipschitz
functions. In between, the sampling problem's degree of difficulty varies,
depending on the values of $\alpha$ and $p$. Surprisingly, we see almost the
entire hierarchy of tractability levels as introduced in the recent monographs
by Novak and Wo\'zniakowski.


title:
Search for Quantum Black-Hole Production in High-Invariant-Mass
  Lepton+Jet Final States Using Proton-Proton Collisions at sqrt(s) = 8 TeV and
  the ATLAS Detector

abstract:
  This Letter presents a search for quantum black-hole production using 20.3
inverse fb of data collected with the ATLAS detector in pp collisions at the
LHC at sqrt(s) = 8 TeV. The quantum black holes are assumed to decay into a
lepton (electron or muon) and a jet. In either channel, no event with a
lepton-jet invariant mass of 3.5 TeV or more is observed, consistent with the
expected background. Limits are set on the product of cross sections and
branching fractions for the lepton+jet final states of quantum black holes
produced in a search region for invariant masses above 1 TeV. The combined 95%
confidence level upper limit on this product for quantum black holes with
threshold mass above 3.5 TeV is 0.18 fb. This limit constrains the threshold
quantum black-hole mass to be above 5.3 TeV in the model considered.


title:
Micro-coil detection of Nuclear Magnetic Resonance for nanofluidic
  samples

abstract:
  We have developed a novel dc SQUID system with a micro-coil input circuit to
act as a local probe of quantum matter and nanosystems. The planar niobium
micro-coil pickup loop is located remotely from the SQUID, coupled through a
superconducting twisted pair, enabling the sample to be at microkelvin
temperatures. A high degree of coupling between the coil and the region of
interest of similar dimensions (up to ~ 100 microns) can be achieved. We report
nuclear magnetic resonance (NMR) measurements to characterise the sensitivity
of these coils to 3He in the gas phase at 4.2 K in a 30 mT magnetic field.


title: Statistical validation of high-dimensional models of growing networks

abstract:
  The abundance of models of complex networks and the current insufficient
validation standards make it difficult to judge which models are strongly
supported by data and which are not. We focus here on likelihood maximization
methods for models of growing networks with many parameters and compare their
performance on artificial and real datasets. While high dimensionality of the
parameter space harms the performance of direct likelihood maximization on
artificial data, this can be improved by introducing a suitable penalization
term. Likelihood maximization on real data shows that the presented approach is
able to discriminate among available network models. To make large-scale
datasets accessible to this kind of analysis, we propose a subset sampling
technique and show that it yields substantial model evidence in a fraction of
time necessary for the analysis of the complete data.


title: On conjugate times of LQ optimal control problems

abstract:
  Motivated by the study of linear quadratic optimal control problems, we
consider a dynamical system with a constant, quadratic Hamiltonian, and we
characterize the number of conjugate times in terms of the spectrum of the
Hamiltonian vector field $\vec{H}$. We prove the following dichotomy: the
number of conjugate times is identically zero or grows to infinity. The latter
case occurs if and only if $\vec{H}$ has at least one Jordan block of odd
dimension corresponding to a purely imaginary eigenvalue. As a byproduct, we
obtain bounds from below on the number of conjugate times contained in an
interval in terms of the spectrum of $\vec{H}$.


title: Natural Factors of the Medvedev Lattice Capturing IPC

abstract:
  Skvortsova showed that there is a factor of the Medvedev lattice which
captures intuitionistic propositional logic (IPC). However, her factor is
unnatural in the sense that it is constructed in an ad hoc manner. We present a
more natural example of such a factor. We also show that for every non-trivial
factor of the Medvedev lattice its theory is contained in Jankov's logic, the
deductive closure of IPC plus the weak law of the excluded middle. This answers
a question by Sorbi and Terwijn.


title: Productively countably tight spaces of the form C_k(X)

abstract:
  Some results in C_k-theory are obtained with the use of bornologies. We
investigate under which conditions the space of the continuous real functions
with the compact-open topology is a productively countably tight space, which
yields some applications on Alster spaces.


title: Quasi-Static Multiple-Antenna Fading Channels at Finite Blocklength

abstract:
  This paper investigates the maximal achievable rate for a given blocklength
and error probability over quasi-static multiple-input multiple-output (MIMO)
fading channels, with and without channel state information (CSI) at the
transmitter and/or the receiver. The principal finding is that outage capacity,
despite being an asymptotic quantity, is a sharp proxy for the
finite-blocklength fundamental limits of slow-fading channels. Specifically,
the channel dispersion is shown to be zero regardless of whether the fading
realizations are available at both transmitter and receiver, at only one of
them, or at neither of them. These results follow from analytically tractable
converse and achievability bounds. Numerical evaluation of these bounds
verifies that zero dispersion may indeed imply fast convergence to the outage
capacity as the blocklength increases. In the example of a particular $1 \times
2$ single-input multiple-output (SIMO) Rician fading channel, the blocklength
required to achieve $90\%$ of capacity is about an order of magnitude smaller
compared to the blocklength required for an AWGN channel with the same
capacity. For this specific scenario, the coding/decoding schemes adopted in
the LTE-Advanced standard are benchmarked against the finite-blocklength
achievability and converse bounds.


title: Google matrix analysis of C.elegans neural network

abstract:
  We study the structural properties of the neural network of the C.elegans
(worm) from a directed graph point of view. The Google matrix analysis is used
to characterize the neuron connectivity structure and node classifications are
discussed and compared with physiological properties of the cells. Our results
are obtained by a proper definition of neural directed network and subsequent
eigenvector analysis which recovers some results of previous studies. Our
analysis highlights particular sets of important neurons constituting the core
of the neural system. The applications of PageRank, CheiRank and ImpactRank to
characterization of interdependency of neurons are discussed.


title: A new stopping criterion for the mean shift iterative algorithm

abstract:
  The mean shift iterative algorithm was proposed in 2006, for using the
entropy as a stopping criterion. From then on, a theoretical base has been
developed and a group of applications has been carried out using this
algorithm. This paper proposes a new stopping criterion for the mean shift
iterative algorithm, where stopping threshold via entropy is used now, but in
another way. Many segmentation experiments were carried out by utilizing
standard images and it was verified that a better segmentation was reached, and
that the algorithm had better stability. An analysis on the convergence,
through a theorem, with the new stopping criterion was carried out. The goal of
this paper is to compare the new stopping criterion with the old criterion. For
this reason, the obtained results were not compared with other segmentation
approaches, since with the old stopping criterion were previously carried out.


title:
Self-similarity, conservation of entropy/bits and the black hole
  information puzzle

abstract:
  John Wheeler coined the phrase "it from bit" or "bit from it" in the 1980s.
However, much of the interest in the connection between information, i.e.
"bits", and physical objects, i.e. "its", stems from the discovery that black
holes have characteristics of thermodynamic systems having entropies and
temperatures. This insight led to the information loss problem -- what happens
to the "bits" when the black hole has evaporated away due to the energy loss
from Hawking radiation? In this essay we speculate on a radical answer to this
question using the assumption of self-similarity of quantum correction to the
gravitational action and the requirement that the quantum corrected entropy be
well behaved in the limit when the black hole mass goes to zero.


title: Local semicircle law with imprimitive variance matrix

abstract:
  We extend the proof of the local semicircle law for generalized Wigner
matrices given in [4] to the case when the matrix of variances has an
eigenvalue $ -1 $. In particular, this result provides a short proof of the
optimal local Marchenko-Pastur law at the hard edge (i.e. around zero) for
sample covariance matrices $ \boldsymbol{\mathrm{X}}^\ast
\boldsymbol{\mathrm{X}} $, where the variances of the entries of $
\boldsymbol{\mathrm{X}} $ may vary.


title:
Emergence of macroscopic directed motion in populations of motile
  colloids

abstract:
  From the formation of animal flocks to the emergence of coordinate motion in
bacterial swarms, at all scales populations of motile organisms display
coherent collective motion. This consistent behavior strongly contrasts with
the difference in communication abilities between the individuals. Guided by
this universal feature, physicists have proposed that solely alignment rules at
the individual level could account for the emergence of unidirectional motion
at the group level. This hypothesis has been supported by agent-based
simulations. However, more complex collective behaviors have been
systematically found in experiments including the formation of vortices,
fluctuating swarms, clustering and swirling. All these model systems
predominantly rely on actual collisions to display collective motion. As a
result, the potential local alignment rules are entangled with more complex,
often unknown, interactions. The large-scale behavior of the populations
therefore depends on these uncontrolled microscopic couplings. Here, we
demonstrate a new phase of active matter. We reveal that dilute populations of
millions of colloidal rollers self-organize to achieve coherent motion along a
unique direction, with very few density and velocity fluctuations. Identifying
the microscopic interactions between the rollers allows a theoretical
description of this polar-liquid state. Comparison of the theory with
experiment suggests that hydrodynamic interactions promote the emergence of
collective motion either in the form of a single macroscopic flock at low
densities, or in that of a homogenous polar phase at higher densities.
Furthermore, hydrodynamics protects the polar-liquid state from the giant
density fluctuations. Our experiments demonstrate that genuine physical
interactions at the individual level are sufficient to set homogeneous active
populations into stable directed motion.


title: Bounds for the Euclidean minima of function fields

abstract:
  In this paper, we define Euclidean minima for function fields and give some
bound for this invariant. We furthermore show that the results are analogous to
those obtained in the number field case.


title: Symmetric Interconnection Networks from Cubic Crystal Lattices

abstract:
  Torus networks of moderate degree have been widely used in the supercomputer
industry. Tori are superb when used for executing applications that require
near-neighbor communications. Nevertheless, they are not so good when dealing
with global communications. Hence, typical 3D implementations have evolved to
5D networks, among other reasons, to reduce network distances. Most of these
big systems are mixed-radix tori which are not the best option for minimizing
distances and efficiently using network resources. This paper is focused on
improving the topological properties of these networks.
  By using integral matrices to deal with Cayley graphs over Abelian groups, we
have been able to propose and analyze a family of high-dimensional grid-based
interconnection networks. As they are built over $n$-dimensional grids that
induce a regular tiling of the space, these topologies have been denoted
\textsl{lattice graphs}. We will focus on cubic crystal lattices for modeling
symmetric 3D networks. Other higher dimensional networks can be composed over
these graphs, as illustrated in this research. Easy network partitioning can
also take advantage of this network composition operation. Minimal routing
algorithms are also provided for these new topologies. Finally, some practical
issues such as implementability and preliminary performance evaluations have
been addressed.


title: On H\"ormander's solution of the dbar-equation

abstract:
  We explain how H\"ormander's classical solution of the dbar-equation in the
plane with a weight which permits growth near infinity carries over to the
rather opposite situation when we ask for decay near infinity. Here, however, a
natural condition on the datum needs to be imposed. The condition is not only
natural but also necessary to have the result at least in the Fock weight case.


title: Graphene physics via the Dirac oscillator in (2+1) dimensions

abstract:
  We show how the two-dimensional Dirac oscillator model can describe some
properties of electrons in graphene. This model explains the origin of the
left-handed chirality observed for charge carriers in monolayer and bilayer
graphene. The relativistic dispersion relation observed for monolayer graphene
is obtained directly from the energy spectrum, while the parabolic dispersion
relation observed for the case of bilayer graphene is obtained in the
non-relativistic limit. Additionally, if an external magnetic field is applied,
the unusual Landau-level spectrum for monolayer graphene is obtained, but for
bilayer graphene the model predicts the existence of a magnetic field-dependent
gap. Finally, this model also leads to the existence of a chiral phase
transition.


title: New constructions and bounds for Winkler's hat game

abstract:
  Hat problems have recently become a popular topic in combinatorics and
discrete mathematics. These have been shown to be strongly related to coding
theory, network coding, and auctions. We consider the following version of the
hat game, introduced by Winkler and studied by Butler et al. A team is composed
of several players; each player is assigned a hat of a given colour; they do
not see their own colour, but can see some other hats, according to a directed
graph. The team wins if they have a strategy such that, for any possible
assignment of colours to their hats, at least one player guesses their own hat
colour correctly. In this paper, we discover some new classes of graphs which
allow a winning strategy, thus answering some of the open questions in Butler
et al. We also derive upper bounds on the maximal number of possible hat
colours that allow for a winning strategy for a given graph.


title: Information dissemination processes in directed social networks

abstract:
  Social networks can have asymmetric relationships. In the online social
network Twitter, a follower receives tweets from a followed person but the
followed person is not obliged to subscribe to the channel of the follower.
Thus, it is natural to consider the dissemination of information in directed
networks. In this work we use the mean-field approach to derive differential
equations that describe the dissemination of information in a social network
with asymmetric relationships. In particular, our model reflects the impact of
the degree distribution on the information propagation process. We further show
that for an important subclass of our model, the differential equations can be
solved analytically.


title:
X-ray and $\gamma$-ray Studies of the Millisecond Pulsar and Possible
  X-ray Binary/Radio Pulsar Transition Object PSR J1723-2837

abstract:
  We present X-ray observations of the "redback" eclipsing radio millisecond
pulsar and candidate radio pulsar/X-ray binary transition object PSR
J1723-2837. The X-ray emission from the system is predominantly non-thermal and
exhibits pronounced variability as a function of orbital phase, with a factor
of ~2 reduction in brightness around superior conjunction. Such temporal
behavior appears to be a defining characteristic of this variety of peculiar
millisecond pulsar binaries and is likely caused by a partial geometric
occultation by the main-sequence-like companion of a shock within the binary.
There is no indication of diffuse X-ray emission from a bow shock or pulsar
wind nebula associated with the pulsar. We also report on a search for point
source emission and $\gamma$-ray pulsations in Fermi Large Area Telescope data
using a likelihood analysis and photon probability weighting. Although PSR
J1723-2837 is consistent with being a $\gamma$-ray point source, due to the
strong Galactic diffuse emission at its position a definitive association
cannot be established. No statistically significant pulsations or modulation at
the orbital period are detected. For a presumed source detection, the implied
$\gamma$-ray luminosity is $\lesssim$5% of its spin-down power. This indicates
that PSR J1723-2837 is either one of the least efficient $\gamma$-ray producing
millisecond pulsars or, if the detection is spurious, the $\gamma$-ray emission
pattern is not directed towards us.


title:
Colloidal templating at a cholesteric - oil interface: Assembly guided
  by an array of disclination lines

abstract:
  We simulate colloids (radius $R \sim 1\mu$m) trapped at the interface between
a cholesteric liquid crystal and an immiscible oil, at which the helical order
(pitch p) in the bulk conflicts with the orientation induced at the interface,
stabilizing an ordered array of disclinations. For weak anchoring strength W of
the director field at the colloidal surface, this creates a template, favoring
particle positions eitheron top of or midway between defect lines, depending on
$\alpha = R/p$. For small $\alpha$, optical microscopy experiments confirm this
picture, but for larger $\alpha$ no templating is seen. This may stem from the
emergence at moderate W of a rugged energy landscape associated with defect
reconnections.


title: Curvature effects in statics and dynamics of a thin magnetic shell

abstract:
  Equations of the magnetization dynamics are derived for an arbitrary curved
2D surface. General static solutions are obtained in the limit of a strong
anisotropy of both signs (easy-surface and easy-normal cases). It is shown that
the effect of the curvature can be treated as appearance of an effective
magnetic field which is aligned along the surface normal for the case of
easy-surface anisotropy and it is tangential to the surface for the case of
easy-normal anisotropy. In general, the existence of such a field denies the
solutions strictly tangential as well as strictly normal to the surface. As an
example we consider static equilibrium solutions and linear dynamics for a cone
surface magnetization.


title: Rapid coherent control of population transfer in lattice systems

abstract:
  We derive the driving potential that accelerates adiabatic population
transfer from an initial state to a target state in a lattice system without
unwanted excitation of other states by extending to discrete systems the
fast-forward theory of adiabatic transfer. As an example we apply the theory to
a model that describes a Bose-Einstein condensate in a quasi one-dimensional
optical lattice, and show that modulation of the tilting of the lattice
potential can transfer the population of the Bose-Einstein condensate from site
to site with high fidelity and without unwanted excitations.


title: Snowmass 2013 Top quark working group report

abstract:
  This report summarizes the work of the Energy Frontier Top Quark working
group of the 2013 Community Summer Study (Snowmass).


title: Stochastic homogenization of a nonconvex Hamilton-Jacobi equation

abstract:
  We present a proof of qualitative stochastic homogenization for a nonconvex
Hamilton-Jacobi equation. The new idea is to introduce a family of
"sub-equations" and to control solutions of the original equation by the
maximal subsolutions of the latter, which have deterministic limits by the
subadditive ergodic theorem and maximality.


title: Spin-noise in the anisotropic central spin model

abstract:
  Spin-noise measurements can serve as direct probe for the microscopic
decoherence mechanism of an electronic spin in semiconductor quantum dots
(QD).We have calculated the spin-noise spectrum in the anisotropic central spin
model using a Chebyshev expansion technique which exactly accounts for the
dynamics up to an arbitrary long but fixed time in a finite size system. In the
isotropic case, describing QD charged with a single electron, the short-time
dynamics is in good agreement with a quasi-static approximation for the
thermodynamic limit. The spin-noise spectrum, however, shows strong deviations
at low frequencies with a power-law behavior. In the Ising limit, applicable to
QDs with heavy-hole spins, the spin-noise spectrum exhibits a threshold
behavior above the Larmor frequency. In the generic anisotropic central spin
model we have found a crossover from a Gaussian type of spin-noise spectrum to
a more Ising-type spectrum with increasing anisotropy in a finite magnetic
field. In order to make contact with experiments, we present ensemble averaged
spin-noise spectra for QD ensembles charged with single electrons or holes. The
Gaussian-type noise spectrum evolves to a more Lorentzian shape spectrum with
increasing spread of characteristic time-scales and g-factors of the individual
QDs.


title:
The nebular spectra of SN 2012aw and constraints on stellar
  nucleosynthesis from oxygen emission lines

abstract:
  We present nebular phase optical and near-infrared spectroscopy of the Type
IIP supernova SN 2012aw combined with NLTE radiative transfer calculations
applied to ejecta from stellar evolution/explosion models. Our spectral
synthesis models generally show good agreement with the ejecta from a MZAMS =
15 Msun progenitor star. The emission lines of oxygen, sodium, and magnesium
are all consistent with the nucleosynthesis in a progenitor in the 14 - 18 Msun
range. We also demonstrate how the evolution of the oxygen cooling lines of [O
I] 5577 A, [O I] 6300 A, and [O I] 6364 A can be used to constrain the mass of
oxygen in the non-molecularly cooled ashes to < 1 Msun, independent of the
mixing in the ejecta. This constraint implies that any progenitor model of
initial mass greater than 20 Msun would be difficult to reconcile with the
observed line strengths. A stellar progenitor of around MZAMS = 15 Msun can
consistently explain the directly measured luminosity of the progenitor star,
the observed nebular spectra, and the inferred pre-supernova mass-loss rate. We
conclude that there is still no convincing example of a Type IIP explosion
showing the nucleosynthesis expected from a MZAMS > 20 Msun progenitor.


title: A Simple, Faster Method for Kinetic Proximity Problems

abstract:
  For a set of $n$ points in the plane, this paper presents simple kinetic data
structures (KDS's) for solutions to some fundamental proximity problems,
namely, the all nearest neighbors problem, the closest pair problem, and the
Euclidean minimum spanning tree (EMST) problem. Also, the paper introduces
KDS's for maintenance of two well-studied sparse proximity graphs, the Yao
graph and the Semi-Yao graph.
  We use sparse graph representations, the Pie Delaunay graph and the
Equilateral Delaunay graph, to provide new solutions for the proximity
problems. Then we design KDS's that efficiently maintain these sparse graphs on
a set of $n$ moving points, where the trajectory of each point is assumed to be
an algebraic function of constant maximum degree $s$. We use the kinetic Pie
Delaunay graph and the kinetic Equilateral Delaunay graph to create KDS's for
maintenance of the Yao graph, the Semi-Yao graph, all the nearest neighbors,
the closest pair, and the EMST. Our KDS's use $O(n)$ space and $O(n\log n)$
preprocessing time.
  We provide the first KDS's for maintenance of the Semi-Yao graph and the Yao
graph. Our KDS processes $O(n^2\beta_{2s+2}(n))$ (resp.
$O(n^3\beta_{2s+2}^2(n)\log n)$) events to maintain the Semi-Yao graph (resp.
the Yao graph); each event can be processed in time $O(\log n)$ in an amortized
sense. Here, $\beta_s(n)$ is an extremely slow-growing function.
  Our KDS for maintenance of all the nearest neighbors and the closest pair
processes $O(n^2\beta^2_{2s+2}(n)\log n)$ events. For maintenance of the EMST,
our KDS processes $O(n^3\beta_{2s+2}^2(n)\log n)$ events. For all three of
these problems, each event can be handled in time $O(\log n)$ in an amortized
sense.
  We improve the previous randomized kinetic algorithm for maintenance of all
the nearest neighbors by Agarwal, Kaplan, and Sharir, and the previous EMST KDS
by Rahmati and Zarei.


title:
Tuning between singlet, triplet, and mixed pairing states in an extended
  Hubbard chain

abstract:
  We study spin-half fermions in a one-dimensional extended Hubbard chain at
low filling. We identify three triplet and one singlet pairing channels in the
system, which are independently tunable as a function of nearest-neighbor
charge and spin interactions. In a large-size system with translational
invariance, we derive gap equations for the corresponding pairing gaps and
obtain a Bogoliubov-de Gennes Hamiltonian with its non-trivial topology
determined by the interplay of these gaps. In an open-end system with a fixed
number of particles, we compute the exact many-body ground state and identify
the dominant pairing revealed by the pair density matrix. Both cases show
competition between the four pairing states, resulting in broad regions for
each of them and relatively narrow regions for mixed-pairing states in the
parameter space. Our results enable the possibility of tuning a nanowire
between singlet and triplet pairing states without breaking time-reversal or
SU(2) symmetry, accompanied by a change in the system's topology.


title:
A robust plasma-based laser amplifier via stimulated Brillouin
  scattering

abstract:
  It is shown here that Brillouin amplification can be used to produce
picosecond pulses of petawatt power. Brillouin amplification is far more
resilient to fluctuations in the laser and plasma parameters than Raman
amplification, making it an attractive alternative to Raman amplification.
Through analytic theory and multi-dimensional computer simulations, a novel,
well-defined parameter regime has been found, distinct from that of Raman
amplification, where pump-to-probe compression ratios of up to 100 and peak
laser fluences over 1 kJ/cm$^2$ with 30\% efficiency have been achieved. High
pulse quality has been maintained through control of parasitic instabilities.


title:
Numerical methods of solutions of boundary value problems for the
  multi-term variable-distributed order diffusion equation

abstract:
  Solutions of the Dirichlet and Robin boundary value problems for the
multi-term variable-distributed order diffusion equation are studied. A priori
estimates for the corresponding differential and difference problems are
obtained by using the method of the energy inequalities. The stability and
convergence of the difference schemes follow from these a priory estimates. The
credibility of the obtained results is verified by performing numerical
calculations for test problems.


title: On the surface paramagnetism of diamond

abstract:
  We present measurements of spin relaxation times (T_1, T_1,rho, T_2) on very
shallow (<5 nm) nitrogen-vacancy (NV) centers in high-purity diamond single
crystals. We find a reduction of spin relaxation times up to 30x compared to
bulk values, indicating the presence of ubiquitous magnetic impurities
associated with the surface. Our measurements yield a density of 0.01-0.1 Bohr
magnetons per nm^2 and a characteristic correlation time of 0.28(3) ns of
surface states, with little variation between samples (implanted, N-doped) and
surface terminations (H, F and O). A low temperature measurement further
confirms that fluctuations are thermally activated. The data support the
atomistic picture where impurities are associated with the top carbon layers,
and not with terminating surface atoms or adsorbate molecules. The low spin
density implies that the presence of a single surface impurity is sufficient to
cause spin relaxation of a shallow NV center.


title: Simple Multi-Party Set Reconciliation

abstract:
  As users migrate information to cloud storage, many distributed cloud-based
services use multiple loosely consistent replicas of user information to avoid
the high overhead of more tightly coupled synchronization. Periodically, the
information must be synchronized, or reconciled. One can place this problem in
the theoretical framework of {\em set reconciliation}: two parties $A_1$ and
$A_2$ each hold a set of keys, named $S_1$ and $S_2$ respectively, and the goal
is for both parties to obtain $S_1 \cup S_2$. Typically, set reconciliation is
interesting algorithmically when sets are large but the set difference
$|S_1-S_2|+|S_2-S_1|$ is small. In this setting the focus is on accomplishing
reconciliation efficiently in terms of communication; ideally, the
communication should depend on the size of the set difference, and not on the
size of the sets.
  In this paper, we extend recent approaches using Invertible Bloom Lookup
Tables (IBLTs) for set reconciliation to the multi-party setting. In this
setting there are three or more parties $A_1,A_2,\ldots,A_n$ holding sets of
keys $S_1,S_2,\ldots,S_n$ respectively, and the goal is for all parties to
obtain $\cup_i S_i$. This could of course be done by pairwise reconciliations,
but we seek more effective methods.
  Our methodology uses network coding techniques in conjunction with IBLTs,
allowing efficiency in network utilization along with efficiency obtained by
passing messages of size $O(|\cup_i S_i - \cap_i S_i|)$. Further, our approach
can function even if the number of parties is not exactly known in advance, and
in many cases can be used to determine which parties contain keys not in the
joint union. By connecting reconciliation with network coding, we can allow for
substantially more efficient reconciliation methods that apply to a number of
natural distributed computing problems.


title: The Rate of Convergence for Approximate Bayesian Computation

abstract:
  Approximate Bayesian Computation (ABC) is a popular computational method for
likelihood-free Bayesian inference. The term "likelihood-free" refers to
problems where the likelihood is intractable to compute or estimate directly,
but where it is possible to generate simulated data $X$ relatively easily given
a candidate set of parameters $\theta$ simulated from a prior distribution.
Parameters which generate simulated data within some tolerance $\delta$ of the
observed data $x^*$ are regarded as plausible, and a collection of such
$\theta$ is used to estimate the posterior distribution $\theta\,|\,X\!=\!x^*$.
Suitable choice of $\delta$ is vital for ABC methods to return good
approximations to $\theta$ in reasonable computational time.
  While ABC methods are widely used in practice, particularly in population
genetics, study of the mathematical properties of ABC estimators is still in
its infancy. We prove that ABC estimates converge to the exact solution under
very weak assumptions and, under slightly stronger assumptions, quantify the
rate of this convergence. Our results can be used to guide the choice of the
tolerance parameter $\delta$.


title: Recent VERITAS Results

abstract:
  VERITAS is an array of four imaging atmospheric Cherenkov telescopes near
Tucson, Arizona and is one of the world's most sensitive detectors of very high
energy (VHE: >100 GeV) gamma rays. The scientific reach of VERITAS covers the
study of both extragalactic and Galactic objects as well as the search for
astrophysical dark matter. In these proceedings we will discuss the status of
VERITAS operations and upgrades and present a selection of recent results.


title: External Sources in Lee-Wick Theories

abstract:
  We investigate some peculiar aspects of the so called Lee-Wick
Electrodynamics focusing on physical effects produced by the presence of
sources for the vector field. The interactions between stationary charges
distributions along parallel branes with arbitrary dimensions is investigated
and the energy of a point charge is discussed. Some physical phenomena produced
in the vicinity of a Dirac string are also investigated. We consider the
Lee-Wick theory for the scalar field, where it can emerge some interesting
effects with no counterpart for the vector gauge field theory.


title:
The circumnuclear environment of NGC613: a nuclear starburst caught in
  the act?

abstract:
  We present near-infrared ($H$- and $K$-band) integral-field observations of
the inner $\sim$700pc of the active spiral galaxy NGC613, obtained with SINFONI
on the Very Large Telescope. We use emission-line ratios to determine the
dominant excitation mechanisms in different regions within our field-of-view,
in particular the active nucleus and the star-forming circum-nuclear ring.
Diagnostic diagrams involving [FeII] and H$_2$ fluxes indicate that the gas is
not only photoionized by the AGN in the nucleus of NGC613, but also
shock-heated. On the other hand, the emission line ratios measured in the ``hot
spots'' along the ring are fully consistent with them being young star forming
regions. We find no sign of radial gas transport from the ring into the core
region dominated by the AGN. The ring morphology appears disturbed by a radial
outflow of material from the AGN, which is confirmed by the existence of a weak
jet in archival radio maps. However, this jet does not seem to have any
significant effect on the morphology of the large ($\sim$8$\times$10$^7$ solar
masses) reservoir of molecular gas that has accumulated inside the central
$\sim$100pc. Such a concentration of molecular gas around an AGN is unusual,
and supports a scenario in which star formation is recurrent and episodic in
spiral galaxies. In this context, NGC613 appears to be in final stages of the
gas accumulation phase, and is likely to undergo a nuclear starburst in the
near future.


title: A Single-Cooper-Pair Josephson Laser

abstract:
  The advent of quantum optical techniques based on superconducting circuits
has opened new regimes in the study of the non-linear interaction of light with
matter. Of particular interest has been the creation of non-classical states of
light, which are essential for continuous-variable quantum information
processing, and could enable quantum-enhanced measurement sensitivity. Here we
demonstrate a device consisting of a superconducting artificial atom, the
Cooper pair transistor, embedded in a superconducting microwave cavity that may
offer a path toward simple, continual production of non-classical photons. By
applying a dc voltage to the atom, we use the ac Josephson effect to inject
photons into the cavity. The backaction of the photons on single-Cooper-pair
tunneling events results in a new regime of simultaneous quantum coherent
transport of Cooper pairs and microwave photons. This single-pair Josephson
laser offers great potential for the production of amplitude-squeezed photon
states and a rich environment for the study of the quantum dynamics of
nonlinear systems.


title:
Time Reversal Symmetric Topological Exciton Condensate in Bilayer HgTe
  Quantum Wells

abstract:
  We investigate a bilayer system of critical HgTe quantum wells each featuring
a spin-degenerate pair of massless Dirac fermions. In the presence of an
electrostatic inter-layer Coulomb coupling, we determine the exciton condensate
order parameter of the system self-consistently. Calculating the bulk
topological $\mathbb Z_2$ invariant of the resulting mean field Hamiltonian, we
discover a novel time reversal symmetric topological exciton condensate state
coined the helical topological exciton condensate. We argue that this phase can
exist for experimentally relevant parameters. Interestingly, due to its
multi-band nature, the present bilayer model exhibits a nontrivial interplay
between spontaneous symmetry breaking and topology: Depending on which symmetry
the condensate order parameter spontaneously picks in combined orbital and spin
space, stable minima in the free energy corresponding to both trivial and
nontrivial gapped states can be found.


title:
Testing the Newborn Pulsar Origin of Ultrahigh Energy Cosmic Rays with
  EeV Neutrinos

abstract:
  Fast-spinning newborn pulsars are intriguing candidate sources of ultrahigh
energy cosmic rays (UHECRs). The acceleration of particles with a given
composition in a fraction of the extragalactic pulsar population can give a
consistent explanation for the measurements of the Auger Observatory. We
calculate the associated diffuse neutrino flux produced while particles cross
the supernova ejecta surrounding the stars. We show that in the minimal pulsar
scenario that are compatible with the UHECR data, the effective optical depth
to hadronuclear interactions is larger than unity at ultrahigh energies. Thus,
even in the most pessimistic case, one expects energy fluxes of $\sim 0.1 - 1
\,\rm EeV$ neutrinos that should be detectable with IceCube or Askaryan Radio
Array within a decade.


title:
Competition between memory-keeping and memory-erasing decoherence
  channels

abstract:
  We study the competing effects of simultaneous Markovian and non-Markovian
decoherence mechanisms acting on a single spin. We show the existence of a
threshold in the relative strength of such mechanisms above which the spin
dynamics becomes fully Markovian, as revealed by the use of several
non-Markovianity measures. We identify a measure-dependent nested structure of
such thresholds, hinting at a causality relationship amongst the various
non-Markovianity witnesses used in our analysis. Our considerations are then
used to argue the unavoidably non-Markovian evolution of a single-electron
quantum dot exposed to both intrinsic and Markovian technical noise, the latter
of arbitrary strength.


title: Extremizers and sharp weak-type estimates for positive dyadic shifts

abstract:
  We find the exact Bellman function for the weak $L^1$ norm of local positive
dyadic shifts. We also describe a sequence of functions, self-similar in
nature, which in the limit extremize the local weak-type (1,1) inequality.


title: Optical coherences and wavelength mismatch in ladder systems

abstract:
  We investigate experimentally and theoretically the coherent and incoherent
processes in open 3-level ladder systems in room temperature gases and identify
in which regime electromagnetically induced transparency (EIT) occurs. The
peculiarity of this work lies in the unusual situation where the wavelength of
the probe field is shorter than that of the coupling field. The nature of the
observed spectral features depends considerably on the total response of
different velocity classes, the varying Doppler shifts for bichromatic
excitation fields, on optical pumping to additional electronic states and
transit time effects. All these ingredients can be absorbed in a model based on
optical Bloch equations with only five electronic states.


title: No Transit Timing Variations in WASP-4

abstract:
  We present 6 new transits of the system WASP-4. Together with 28 light curves
published in the literature, we perform an homogeneous study of its parameters
and search for variations in the transit's central times. The final values
agree with those previously reported, except for a slightly lower inclination.
We find no significant long-term variations in $i$ or $R_{P}/R_{\star}$. The
$O-C$ mid-transit times do not show signs of TTVs greater than 54 s.


title: Anomalous minimum in the shear viscosity of a Fermi gas

abstract:
  We measure the static shear viscosity $\eta$ in a two-component Fermi gas
near a broad collisional (Feshbach) resonance, as a function of interaction
strength and energy. We find that $\eta$ has both a quadratic and a linear
dependence on the interaction strength $1/({k_{FI}a})$, where $a$ is the s-wave
scattering length and $k_{FI}$ is the Fermi wave vector for an ideal gas at the
trap center. For energies above the superfluid transition, the minimum in
$\eta$ as a function of interaction strength is significantly shifted toward
the BEC side of resonance, to $1/(k_{FI}a)\simeq 0.25$.