title: Quiescent nuclear burning in low-metallicity white dwarfs

abstract:
  We discuss the impact of residual nuclear burning in the cooling sequences of
hydrogen-rich DA white dwarfs with very low metallicity progenitors
($Z=0.0001$). These cooling sequences are appropriate for the study of very old
stellar populations. The results presented here are the product of
self-consistent, fully evolutionary calculations. Specifically, we follow the
evolution of white dwarf progenitors from the zero-age main sequence through
all the evolutionary phases, namely the core hydrogen-burning phase, the
helium-burning phase, and the thermally pulsing asymptotic giant branch phase
to the white dwarf stage. This is done for the most relevant range of main
sequence masses, covering the most usual interval of white dwarf masses ---
from $0.53\, M_{\sun}$ to $0.83\, M_{\sun}$. Due to the low metallicity of the
progenitor stars, white dwarfs are born with thicker hydrogen envelopes,
leading to more intense hydrogen burning shells as compared with their solar
metallicity counterparts. We study the phase in which nuclear reactions are
still important and find that nuclear energy sources play a key role during
long periods of time, considerably increasing the cooling times from those
predicted by standard white dwarf models. In particular, we find that for this
metallicity and for white dwarf masses smaller than about $0.6\, M_{\sun}$,
nuclear reactions are the main contributor to the stellar luminosity for
luminosities as low as $\log(L/L_{\sun})\simeq -3.2$. This, in turn, should
have a noticeable impact in the white dwarf luminosity function of
low-metallicity stellar populations.


title:
Signal Reconstruction via H-infinity Sampled-Data Control Theory: Beyond
  the Shannon Paradigm

abstract:
  This paper presents a new method for signal reconstruction by leveraging
sampled-data control theory. We formulate the signal reconstruction problem in
terms of an analog performance optimization problem using a stable
discrete-time filter. The proposed H-infinity performance criterion naturally
takes intersample behavior into account, reflecting the energy distributions of
the signal. We present methods for computing optimal solutions which are
guaranteed to be stable and causal. Detailed comparisons to alternative methods
are provided. We discuss some applications in sound and image reconstruction.


title: ALD grown zinc oxide with controllable electrical properties

abstract:
  The paper presents results for zinc oxide films grown at low temperature
regime by Atomic Layer Deposition (ALD). We discuss electrical properties of
such films and show that low temperature deposition results in oxygen-rich ZnO
layers in which free carrier concentration is very low. For optimized ALD
process it can reach the level of 10^15 cm-3, while mobility of electrons is
between 20 and 50 cm2/Vs. Electrical parameters of ZnO films deposited by ALD
at low temperature regime are appropriate for constructing of the ZnO-based p-n
and Schottky junctions. We demonstrate that such junctions are characterized by
the rectification ratio high enough to fulfill requirements of 3D memories and
are deposited at temperature 100degC which makes them appropriate for
deposition on organic substrates.


title:
A plausible (overlooked) super-luminous supernova in the SDSS Stripe 82
  data

abstract:
  We present the discovery of a plausible super-luminous supernova (SLSN),
found in the archival data of Sloan Digital Sky Survey (SDSS) Stripe 82, called
PSN 000123+000504. The supernova peaked at M_g<-21.3 mag in the second half of
September 2005, but was missed by the real-time supernova hunt. The observed
part of the light curve (17 epochs) showed that the rise to the maximum took
over 30 days, while the decline time lasted at least 70 days (observed frame),
closely resembling other SLSNe of SN2007bi type. Spectrum of the host galaxy
reveals a redshift of z=0.281 and the distance modulus of \mu=40.77 mag.
Combining this information with the SDSS photometry, we found the host galaxy
to be an LMC-like irregular dwarf galaxy with the absolute magnitude of
M_B=-18.2+/-0.2 mag and the oxygen abundance of 12+log[O/H]=8.3+/-0.2. Our SLSN
follows the relation for the most energetic/super-luminous SNe exploding in
low-metallicity environments, but we found no clear evidence for SLSNe to
explode in low-luminosity (dwarf) galaxies only. The available information on
the PSN 000123+000504 light curve suggests the magnetar-powered model as a
likely scenario of this event. This SLSN is a new addition to a quickly growing
family of super-luminous SNe.


title: Parallel Simulations for Analysing Portfolios of Catastrophic Event Risk

abstract:
  At the heart of the analytical pipeline of a modern quantitative
insurance/reinsurance company is a stochastic simulation technique for
portfolio risk analysis and pricing process referred to as Aggregate Analysis.
Support for the computation of risk measures including Probable Maximum Loss
(PML) and the Tail Value at Risk (TVAR) for a variety of types of complex
property catastrophe insurance contracts including Cat eXcess of Loss (XL), or
Per-Occurrence XL, and Aggregate XL, and contracts that combine these measures
is obtained in Aggregate Analysis.
  In this paper, we explore parallel methods for aggregate risk analysis. A
parallel aggregate risk analysis algorithm and an engine based on the algorithm
is proposed. This engine is implemented in C and OpenMP for multi-core CPUs and
in C and CUDA for many-core GPUs. Performance analysis of the algorithm
indicates that GPUs offer an alternative HPC solution for aggregate risk
analysis that is cost effective. The optimised algorithm on the GPU performs a
1 million trial aggregate simulation with 1000 catastrophic events per trial on
a typical exposure set and contract structure in just over 20 seconds which is
approximately 15x times faster than the sequential counterpart. This can
sufficiently support the real-time pricing scenario in which an underwriter
analyses different contractual terms and pricing while discussing a deal with a
client over the phone.


title: On a certain family of inverse ternary cyclotomic polynomials

abstract:
  We study a family of inverse ternary cyclotomic polynomials $\Psi_{pqr}$ in
which $r\le\varphi(pq)$ is a positive linear combination of $p$ and $q$. We
derive a formula for the height of such polynomial and characterize all flat
polynomials in this family.


title:
2d-4d Connection between q-Virasoro/W Block at Root of Unity Limit and
  Instanton Partition Function on ALE Space

abstract:
  We propose and demonstrate a limiting procedure in which, starting from the
q-lifted version (or K-theoretic five dimensional version) of the (W)AGT
conjecture to be assumed in this paper, the Virasoro/W block is generated in
the r-th root of unity limit in q in the 2d side, while the same limit
automatically generates the projection of the five dimensional instanton
partition function onto that on the ALE space R^4/Z_r. This circumvents
case-by-case conjectures to be made in a wealth of examples found so far. In
the 2d side, we successfully generate the super-Virasoro algebra and the proper
screening charge in the q -> -1, t -> -1 limit, from the defining relation of
the q-Virasoro algebra and the q-deformed Heisenberg algebra. The central
charge obtained coincides with that of the minimal series carrying odd integers
of the N=1 superconformal algebra. In the r-th root of unity limit in q in the
2d side, we give some evidence of the appearance of the parafermion-like
currents. Exploiting the q-analysis literatures, q-deformed su(n) block is
readily generated both at generic q, t and the r-th root of unity limit. In the
4d side, we derive the proper normalization function for general (n, r) that
accomplishes the automatic projection through the limit.


title:
Finite p-groups, entropy vectors and the Ingleton inequality for
  nilpotent groups

abstract:
  In this paper we study the capacity/entropy region of finite, directed,
acyclic, multiple-sources, multiple-sinks network by means of group theory and
entropy vectors coming from groups. There is a one-to-one correspondence
between the entropy vector of a collection of n random variables and a certain
group-characterizable vector obtained from a finite group and n of its
subgroups. We are looking at nilpotent group characterizable entropy vectors
and show that they are all also Abelian group characterizable, and hence they
satisfy the Ingleton inequality. It is known that not all entropic vectors can
be obtained from Abelian groups, so our result implies that in order to get
more exotic entropic vectors, one has to go at least to soluble groups or
larger nilpotency classes. The result also implies that Ingleton inequality is
satisfied by nilpotent groups of bounded class, depending on the order of the
group.


title: Tearing mode stability calculations with pressure flattening

abstract:
  Calculations of tearing mode stability in tokamaks split conveniently into an
external region, where marginally stable ideal MHD is applicable, and a
resonant layer around the rational surface where sophisticated kinetic physics
is needed. These two regions are coupled by the stability parameter. Pressure
and current perturbations localized around the rational surface alter the
stability of tearing modes. Equations governing the changes in the external
solution and - are derived for arbitrary perturbations in axisymmetric toroidal
geometry. The relationship of - with and without pressure flattening is
obtained analytically for four pressure flattening functions. Resistive MHD
codes do not contain the appropriate layer physics and therefore cannot predict
stability directly. They can, however, be used to calculate -. Existing methods
(Ham et al. 2012 Plasma Phys. Control. Fusion 54 025009) for extracting - from
resistive codes are unsatisfactory when there is a finite pressure gradient at
the rational surface and favourable average curvature because of the Glasser
stabilizing effect. To overcome this difficulty we introduce a specific
pressure flattening function that allows the earlier approach to be used. The
technique is first tested numerically in cylindrical geometry with an
artificial favourable curvature. Its application to toroidal geometry is then
demonstrated using the toroidal tokamak tearing mode stability code T7
(Fitzpatrick et al. 1993 Nucl. Fusion 33 1533) which uses an approximate
analytic equilibrium. The prospects for applying this approach to resistive MHD
codes such as MARS-F (Liu et al. 2000 Phys. Plasmas 7 3681) which utilize a
fully toroidal equilibrium are discussed.


title:
A multiple-relaxation-time lattice Boltzmann model for convection heat
  transfer in porous media

abstract:
  In this paper, a two-dimensional (2D) multiple-relaxation-time (MRT) lattice
Boltzmann (LB) model is developed for simulating convection heat transfer in
porous media at the representative elementary volume scale. In the model, a
MRT-LB equation is used to simulate the flow field, while another MRT-LB
equation is employed to simulate the temperature field. The effect of the
porous media is considered by introducing the porosity into the equilibrium
moments, and adding a forcing term to the MRT-LB equation of the flow field in
the moment space. The present MRT-LB model is validated by numerical
simulations of several 2D convection problems in porous media. The numerical
results are in good agreement with the well-documented data reported in the
literature.


title: High TMR ratio in Co2FeSi and Fe2CoSi based magnetic tunnel junctions

abstract:
  Magnetic tunnel junctions with Fe1+xCo2-xSi (0 < x < 1) electrodes and MgO
barrier were prepared on MgO substrates by magnetron co-sputtering. Maximum
tunnel magnetoresistance (TMR) ratios of 262 % at 15 K and 159 % at room
temperature were observed for x=0.75. Correlations of the annealing temperature
dependent atomic ordering and TMR amplitude are discussed. The high TMR for an
intermediate stoichiometry is ascribed to the adjustment of the Fermi energy
within a minority spin pseudo gap.


title:
Detection of Alpha Particles and Low Energy Gamma Rays by Thermo-Bonded
  Micromegas in Xenon Gas

abstract:
  Micromegas is a type of micro-pattern gaseous detector currently under R&D
for applications in rare event search experiments. Here we report the
performance of a Micromegas structure constructed with a micromesh
thermo-bonded to a readout plane, motivated by its potential application in
two-phase xenon detectors for dark matter and neutrinoless double beta decay
experiments. The study is carried out in pure xenon at room temperature.
Measurements with alpha particles from the Americium-241 source showed that gas
gains larger than 200 can be obtained at xenon pressure up to 3 atm. Gamma rays
down to 8 keV were observed with such a device.


title: Low-Frequency Terrestrial Gravitational-Wave Detectors

abstract:
  Direct detection of gravitational radiation in the audio band is being
pursued with a network of kilometer-scale interferometers (LIGO, Virgo, KAGRA).
Several space missions (LISA, DECIGO, BBO) have been proposed to search for
sub-Hz radiation from massive astrophysical sources. Here we examine the
potential sensitivity of three ground-based detector concepts aimed at
radiation in the 0.1 -- 10\,Hz band. We describe the plethora of potential
astrophysical sources in this band and make estimates for their event rates and
thereby, the sensitivity requirements for these detectors. The scientific
payoff from measuring astrophysical gravitational waves in this frequency band
is great. Although we find no fundamental limits to the detector sensitivity in
this band, the remaining technical limits will be extremely challenging to
overcome.


title: The Minimum Spectral Radius of Graphs with the Independence Number

abstract:
  In this paper, we investigate some properties of the Perron vector of
connected graphs. These results are used to characterize that all extremal
connected graphs with having the minimum (maximum) spectra radius among all
connected graphs of order $n=k\alpha$ with the independence number $\alpha$,
respectively.


title:
High resolution scanning tunnelling microscopy and extended
  x-ray-absorption fine structure study of the (533) silicide structure on
  Cu(001)

abstract:
  Using low energy electron diffraction (LEED), scanning tunnelling microscopy
(STM) and x-ray absorption spectroscopy (XAS) techniques, we have studied the
first steps of silicon adsorption onto Cu (001) single crystal substrate. For
low coverage (~ 0.5 ML) and after annealing at 100{\deg}C, STM images and LEED
patterns reveal the formation of an ordered quasi commensurate superstructure.
From a quantitative analysis of XAS data, we extract the Si-Cu distance and
detail the local atomic arrangement of the structure.


title: Chern-Simons theory coupled to bifundamental scalars

abstract:
  We study the three-dimensional theory of two Chern-Simons gauge fields
coupled to a scalar field in the bifundamental representation of the $SU(N)_k
\times SU(M)_{-k}$ gauge group. At small but fixed $M \ll N$, this system
approaches the theory of a Chern-Simons field coupled to fundamental matter,
conjectured to be dual to a parity-violating version of Vasiliev's higher-spin
gauge theory in $AdS_4$. At finite $M/N$ and large 't Hooft coupling this
theory (or its SUSY version) is expected to be dual to an Einstein-like
gravity. We show at two loops that this theory possesses a line of fixed points
at any value of $M/N$. We also prove that turning on a finite but small $M/N$
gaps out the light states that Chern-Simons theory coupled to fundamental
matter develops when placed on a torus. We also comment on the higher genus
case.


title:
Microwave control electrodes for scalable, parallel, single-qubit
  operations in a surface-electrode ion trap

abstract:
  We propose a surface ion trap design incorporating microwave control
electrodes for near-field single-qubit control. The electrodes are arranged so
as to provide arbitrary frequency, amplitude and polarization control of the
microwave field in one trap zone, while a similar set of electrodes is used to
null the residual microwave field in a neighbouring zone. The geometry is
chosen to reduce the residual field to the 0.5% level without nulling fields;
with nulling, the crosstalk may be kept close to the 0.01% level for realistic
microwave amplitude and phase drift. Using standard photolithography and
electroplating techniques, we have fabricated a proof-of-principle electrode
array with two trapping zones. We discuss requirements for the microwave drive
system and prospects for scalability to a large two-dimensional trap array.


title: Stability windows at finite temperature

abstract:
  The assumption underlying the existence of quark stars is based on the
Bodmer-Witten conjecture. These authors have claimed that it is possible that
the interior of a neutron-like star does not consist primarily of hadrons, but
rather of the strange matter (SM). Strange matter is composed of deconfined
quarks, including up, down and strange quarks, plus the leptons necessary to
ensure charge neutrality and \beta-equilibrium. This possibility arises because
a phase transition from hadronic to quark phase is possible at densities
present in the interior of neutron stars. It has been argued that strange
matter is the true ground state of all matter. If this is the case, as soon as
the core of the star converts to the quark phase, the entire star converts. SM
was first considered in calculations obtained within the MIT bag model
framework. More sophisticated treatments for SM, based on the quark-mass
density dependent model is considered in this work. We discuss next the
following models for proto-quark stars: the QMDD model, and the MIT bag model.


title:
Coulomb-assisted cavity feeding in the non-resonant optical emission
  from a quantum dot

abstract:
  Recent experiments have demonstrated that for a quantum dot in an optical
resonator off-resonant cavity mode emission can occur even for detunings of the
order of 10 meV. We show that Coulomb mediated Auger processes based on
additional carriers in delocalized states can facilitate this far off-resonant
emission. Using a novel theoretical approach for a non-perturbative treatment
of the Auger-assisted quantum-dot carrier recombination, we present numerical
calculations of the far off-resonant cavity feeding rate and cavity mean photon
number confirming efficient coupling at higher densities of carriers in the
delocalized states. In comparison to fast Auger-like intraband scattering
processes, we find a reduced overall efficiency of Coulomb-mediated interband
transitions due the required electron-hole correlations for the recombination
processes.


title:
Anomalous transport in fractal media with randomly inhomogeneous
  diffusion barrier

abstract:
  We investigate a contaminant transport in fractal media with randomly
inhomogeneous diffusion barrier. The diffusion barrier is a low permeable
matrix with extremely rare high permeability pathways (punctures). At times,
less than a characteristic matrix diffusion time, the problem is effectively
barrier-free with an effective source acting during the time t<<teff. The
punctures result in a precursor contaminant concentration at short times and
additional stage of the asymptotic concentration distribution at long times. If
the size of the source surface area is large enough, the barrier can be
considered as statistical homogeneous medium; otherwise, strong fluctuations
occur.


title:
Relativistic and thermal effects on the magnon spectrum of a
  ferromagnetic monolayer

abstract:
  A spin model including magnetic anisotropy terms and Dzyaloshinsky-Moriya
interactions is studied for the case of a ferromagnetic monolayer with C2v
symmetry like Fe/W(110). Using the quasiclassical stochastic
Landau-Lifshitz-Gilbert equations, the magnon spectrum of the system is derived
using linear response theory. The Dzyaloshinsky-Moriya interaction leads to
asymmetry in the spectrum, while the anisotropy terms induce a gap. It is shown
that in the presence of lattice defects, both the Dzyaloshinsky-Moriya
interactions and the two-site anisotropy lead to a softening of the magnon
energies. Two methods are developed to investigate the magnon spectrum at
finite temperatures. The theoretical results are compared to atomistic spin
dynamics simulations and a good agreement is found between them.


title: Informationally complete sets of Gaussian measurements

abstract:
  We prove necessary and sufficient conditions for the informational
completeness of an arbitrary set of Gaussian observables on continuous variable
systems with finite number of degrees of freedom. In particular, we show that
an informationally complete set either contains a single informationally
complete observable, or includes infinitely many observables. We show that for
a single informationally complete observable, the minimal outcome space is the
phase space, and the observable can always be obtained from the quantum optical
$Q$-function by linear postprocessing and Gaussian convolution, in a suitable
symplectic coordinatization of the phase space. In the case of projection
valued Gaussian observables, e.g., generalized field quadratures, we show that
an informationally complete set of observables is necessarily infinite.
Finally, we generalize the treatment to the case where the measurement coupling
is given by a general linear bosonic channel, and characterize informational
completeness for an arbitrary set of the associated observables.


title: Universal scaling properties of extremal cohesive holographic phases

abstract:
  We show that strongly-coupled, translation-invariant holographic IR phases at
finite density can be classified according to the scaling behaviour of the
metric, the electric potential and the electric flux introducing four critical
exponents, independently of the details of the setup. Solutions fall into two
classes, depending on whether they break relativistic symmetry or not. The
critical exponents determine key properties of these phases, like thermodynamic
stability, the (ir)relevant deformations around them, the low-frequency scaling
of the optical conductivity and the nature of the spectrum for electric
perturbations. We also study the scaling behaviour of the electric flux through
bulk minimal surfaces using the Hartnoll-Radicevic order parameter, and
characterize the deviation from the Ryu-Takayanagi prescription in terms of the
critical exponents.


title:
Localized Fermions on Domain Walls and Extended Supersymmetric Quantum
  Mechanics

abstract:
  We study fermionic fields localized on topologically unstable domain walls
bounded by strings in a grand unified theory theoretical framework.
Particularly, we found that the localized fermionic degrees of freedom, which
are up and down quarks as long as charged leptons, are connected to three
independent N=2, $d=1$ supersymmetric quantum mechanics algebras. As we
demonstrate, these algebras can be combined to form higher order
representations of N=2, $d=1$ supersymmetry. Due to the uniform coupling of the
domain wall solutions to the down-quarks and leptons, we also show that a
higher order N=2, $d=1$ representation of the down-quark--lepton system is
invariant under a duality transformation between the couplings. In addition,
the two N=2, $d=1$ supersymmetries of the down-quark--lepton system, combine at
the coupling unification scale to an N=4, $d=1$ supersymmetry. Furthermore, we
present the various extra geometric and algebraic attributes that the fermionic
systems acquire, owing to the underlying N=2, $d=1$ algebras.


title:
Establishing the astrophysical origin of a signal in a neutrino
  telescope

abstract:
  Recently the IceCube collaboration has reported the observation of 28
contained events with a visible energy in the interval between 60 TeV and 1.5
PeV, and has argued that this detection is evidence, with a statistical
significance of more than four standard deviations, for the existence of an
astrophysical neutrino flux that accounts for a large fraction of the events.
In this work we analyze the arguments that allow to identify a component of
astrophysical origin in the high energy neutrino flux separating it from
atmospheric neutrinos. An astrophysical origin for a large fraction of the
IceCube contained events is the simplest and most natural explanation of the
data but, conservatively, an atmospheric origin cannot yet be entirely ruled
out. This ambiguity should soon be resolved.


title:
An Efficient Policy Iteration Algorithm for Dynamic Programming
  Equations

abstract:
  We present an accelerated algorithm for the solution of static
Hamilton-Jacobi-Bellman equations related to optimal control problems. Our
scheme is based on a classic policy iteration procedure, which is known to have
superlinear convergence in many relevant cases provided the initial guess is
sufficiently close to the solution. In many cases, this limitation degenerates
into a behavior similar to a value iteration method, with an increased
computation time. The new scheme circumvents this problem by combining the
advantages of both algorithms with an efficient coupling. The method starts
with a value iteration phase and then switches to a policy iteration procedure
when a certain error threshold is reached. A delicate point is to determine
this threshold in order to avoid cumbersome computation with the value
iteration and, at the same time, to be reasonably sure that the policy
iteration method will finally converge to the optimal solution. We analyze the
methods and efficient coupling in a number of examples in dimension two, three
and four illustrating its properties.


title: Scaffolds and Generalized Integral Galois Module Structure

abstract:
  Let $L/K$ be a finite, totally ramified $p$-extension of complete local
fields with residue fields of characteristic $p > 0$, and let $A$ be a
$K$-algebra acting on $L$. We define the concept of an $A$-scaffold on $L$,
thereby extending and refining the notion of a Galois scaffold considered in
several previous papers, where $L/K$ was Galois and $A=K[G]$ for
$G=\mathrm{Gal}(L/K)$. When a suitable $A$-scaffold exists, we show how to
answer questions generalizing those of classical integral Galois module theory.
We give a necessary and sufficient condition, involving only numerical
parameters, for a given fractional ideal to be free over its associated order
in $A$. We also show how to determine the number of generators required when it
is not free, along with the embedding dimension of the associated order. In the
Galois case, the numerical parameters are the ramification breaks associated
with $L/K$. We apply these results to biquadratic Galois extensions in
characteristic 2, and to totally and weakly ramified Galois $p$-extensions in
characteristic $p$. We also apply our results to the non-classical situation
where $L/K$ is a finite primitive purely inseparable extension of arbitrary
exponent that is acted on, via a higher derivation (but in many different
ways), by the divided power $K$-Hopf algebra.


title:
Pre- and post-selected quantum states: density matrices, tomography, and
  Kraus operators

abstract:
  We present a general formalism for charecterizing 2-time quantum states,
describing pre- and post-selected quantum systems. The most general 2-time
state is characterized by a `density vector' that is independent of
measurements performed between the preparation and post-selection. We provide a
method for performing tomography of an unknown 2-time density vector. This
procedure, which cannot be implemented by weak or projective measurements,
brings new insight to the fundamental role played by Kraus operators in quantum
measurements. Finally, after showing that general states and measurements are
isomorphic, we show that any measurement on a 2-time state can be mapped to a
measurement on a preselected bipartite state.


title: An XMM-Newton view of the merging activity in the Centaurus cluster

abstract:
  We report the results of XMM-Newton observations of the regions around the
core of the Centaurus cluster where evidence for merging activity between the
subgroup Cen 45 and the main Centaurus cluster has previously been observed
using ASCA and ROSAT data. We confirm the ASCA findings of a temperature excess
surrounding Cen 45. We find that this temperature excess can be explained using
simple shock heating given the large line of sight velocity difference between
Cen 45 and the surrounding main Centaurus cluster. We find that there is a
statistically significant excess in metallicity around Cen 45, showing that Cen
45 has managed to retain its gas as it has interacted with the main Centaurus
cluster. There is a pressure excess to the east in the direction of the merger,
and there is also an entropy excess around the central galaxy of Cen 45. The
metallicity between 50-100 kpc to the north of NGC 4696 is higher than to the
south, which may be the result of the asymmetric distribution of metals due to
previous sloshing of the core, or which may be associated with the filamentary
structure we detect between NGC 4696 and NGC 4696B.


title:
On the number of integral quadratic polynomials with bounded heights and
  discriminants

abstract:
  In the paper we obtain the asymtotic number of integral quadratic polynomials
with bounded heights and discriminants as the upper bound of heights tends to
infinity.


title: Sufficient Conditions for Large Galois Scaffolds

abstract:
  Let $L/K$ be a finite Galois, totally ramified $p$-extension of complete
local fields with perfect residue fields of characteristic $p>0$. In this
paper, we give conditions, valid for any Galois $p$-group $G={Gal}(L/K)$
(abelian or not) and for $K$ of either possible characteristic (0 or $p$), that
are sufficient for the existence of a Galois scaffold. The existence of a
Galois scaffold makes it possible to address questions of integral Galois
module structure, which is done in a separate paper. But since our conditions
can be difficult to check, we specialize to elementary abelian extensions and
extend the main result of [G.G. Elder, Proc. A.M.S. 137 (2009), 1193-1203] from
characteristic $p$ to characteristic 0. This result is then applied, using a
result of Bondarko, to the construction of new Hopf orders over the valuation
ring $\mathfrak{O}_K$ that lie in $K[G]$ for $G$ an elementary abelian
$p$-group.


title: Aharonov-Bohm effect, local field interaction, and Lorentz invariance

abstract:
  A field-interaction scheme is introduced for describing the Aharonov-Bohm
effect, fully consistent with the principle of relativity. Our theory is based
on the fact that local field interactions are present even when a particle
moves only in a field-free region. The interaction Lagrangian between a charge
and a flux is uniquely constructed from three principles: Lorentz covariance,
linearity in the interaction strength, and a correct stationary limit of
charge. Our result resolves fundamental questions raised on the standard
interpretation of the Aharonov-Bohm effect, concerning its duality with the
Aharonov-Casher effect and the equivalence between the potential and the
field-interaction models for describing the electromagnetic interaction. Most
of all, potential is eliminated in our theory, and all kind of the force-free
Aharonov-Bohm effect is understood in a unified framework of the
Lorentz-covariant local interaction of electromagnetic fields.


title:
The influence of defects on the conductivity of graphene within the
  effective theory approach

abstract:
  The results of the simulations by Monte Carlo method of graphene with
structural defects are presented.
  The calculations are performed within an effective quantum field theory with
non-compact $3\hm + 1$--dimensional Abelian gauge field and $2\hm +
1$--dimensional Kogut-Susskind fermions. It was found that defects shift the
phase transition point semimetal-insulator towards higher values of a substrate
permittivity.


title:
Observation of transverse condensation via Hanbury Brown--Twiss
  correlations

abstract:
  A fundamental property of a three-dimensional Bose-Einstein condensate (BEC)
is long-range coherence, however, in systems of lower dimensionality, not only
is the long range coherence destroyed, but additional states of matter are
predicted to exist. One such state is a `transverse condensate', first
predicted by van Druten and Ketterle [Phys. Rev. Lett. 79, 549 (1997)], in
which the gas condenses in the transverse dimensions of a highly anisotropic
trap while remaining thermal in the longitudinal dimension. Here we detect the
transition from a three-dimensional thermal gas to a gas undergoing transverse
condensation by probing Hanbury Brown--Twiss correlations.


title: Defensive alliances in graphs: a survey

abstract:
  A set $S$ of vertices of a graph $G$ is a defensive $k$-alliance in $G$ if
every vertex of $S$ has at least $k$ more neighbors inside of $S$ than outside.
This is primarily an expository article surveying the principal known results
on defensive alliances in graph. Its seven sections are: Introduction,
Computational complexity and realizability, Defensive $k$-alliance number,
Boundary defensive $k$-alliances, Defensive alliances in Cartesian product
graphs, Partitioning a graph into defensive $k$-alliances, and Defensive
$k$-alliance free sets.


title: Search for Z_c^+(3900) in the 1^+- channel on the lattice

abstract:
  Recently three experiments reported a discovery of manifestly exotic
Z_c^+(3900) in the decay to J/psi pi+, while J and P are experimentally
unknown. We search for this state on the lattice by simulating the channel with
J^PC=1^+- and I=1, and we do not find a candidate for Z_c^+(3900). Instead, we
only find discrete scattering states D D* and J/psi pi, which inevitably have
to be present in a dynamical QCD. The possible reasons for not finding $Z_c^+$
may be that its quantum numbers are not $1^{+-}$ or that the employed
interpolating fields are not diverse enough. Simulations with additional types
of interpolators will be needed to reach a more definite conclusion.


title:
KASCADE-Grande measurements of energy spectra for elemental groups of
  cosmic rays

abstract:
  The KASCADE-Grande experiment, located at KIT-Karlsruhe, Germany, consists of
a large scintillator array for measurements of charged particles, N_ch, and of
an array of shielded scintillation counters used for muon counting, N_mu.
KASCADE-Grande is optimized for cosmic ray measurements in the energy range 10
PeV to 1000 PeV, thereby enabling the verification of a knee in the iron
spectrum expected at approximately 100 PeV. Exploring the composition in this
energy range is of fundamental importance for understanding the transition from
galactic to extragalactic cosmic rays. Following earlier studies of elemental
spectra reconstructed in the knee energy range from KASCADE data, we have now
extended these measurements to beyond 100 PeV. By analysing the two-dimensional
shower size spectrum N_ch vs. N_mu, we reconstruct the energy spectra of
different mass groups by means of unfolding methods. The procedure and its
results, giving evidence for a knee-like structure in the spectrum of iron
nuclei, will be presented.


title: Synchrotron radiation from a runaway electron distribution in tokamaks

abstract:
  The synchrotron radiation emitted by runaway electrons in a fusion plasma
provides information regarding the particle momenta and pitch-angles of the
runaway electron population through the strong dependence of the synchrotron
spectrum on these parameters. Information about the runaway density and its
spatial distribution, as well as the time evolution of the above quantities,
can also be deduced. In this paper we present the synchrotron radiation spectra
for typical avalanching runaway electron distributions. Spectra obtained for a
distribution of electrons are compared to the emission of mono-energetic
electrons with a prescribed pitch-angle. We also examine the effects of
magnetic field curvature and analyse the sensitivity of the resulting spectrum
to perturbations to the runaway distribution. The implications for the deduced
runaway electron parameters are discussed. We compare our calculations to
experimental data from DIII-D and estimate the maximum observed runaway energy.


title:
Primordial 4He abundance: a determination based on the largest sample of
  HII regions with a methodology tested on model HII regions

abstract:
  We verified the validity of the empirical method to derive the 4He abundance
used in our previous papers by applying it to CLOUDY (v13.01) models. Using
newly published HeI emissivities, for which we present convenient fits as well
as the output CLOUDY case B hydrogen and HeI line intensities, we found that
the empirical method is able to reproduce the input CLOUDY 4He abundance with
an accuracy of better than 1%. The CLOUDY output data also allowed us to derive
the non-recombination contribution to the intensities of the strongest Balmer
hydrogen Halpha, Hbeta, Hgamma, and Hdelta emission lines and the ionisation
correction factors for He. With these improvements we used our updated
empirical method to derive the 4He abundances and to test corrections for
several systematic effects in a sample of 1610 spectra of low-metallicity
extragalactic HII regions, the largest sample used so far. From this sample we
extracted a subsample of 111 HII regions with Hbeta equivalent width EW(Hbeta)
> 150A, with excitation parameter x = O^{2+}/O > 0.8, and with helium mass
fraction Y derived with an accuracy better than 3%. With this subsample we
derived the primordial 4He mass fraction Yp = 0.254+/-0.003 from linear
regression Y-O/H. The derived value of Yp is higher at the 68% confidence level
(CL) than that predicted by the standard big bang nucleosynthesis (SBBN) model,
possibly implying the existence of different types of neutrino species in
addition to the three known types of active neutrinos. Using the most recently
derived primordial abundances D/H = (2.60+/-0.12)x10^{-5} and Yp =
0.254+/-0.003 and the chi^2 technique, we found that the best agreement between
abundances of these light elements is achieved in a cosmological model with
baryon mass density Omegab h^2 = 0.0234+/-0.0019 (68% CL) and an effective
number of the neutrino species Neff = 3.51+/-0.35 (68% CL).


title: Fast Recognition of Partial Star Products and Quasi Cartesian Products

abstract:
  This paper is concerned with the fast computation of a relation $\R$ on the
edge set of connected graphs that plays a decisive role in the recognition of
approximate Cartesian products, the weak reconstruction of Cartesian products,
and the recognition of Cartesian graph bundles with a triangle free basis.
  A special case of $\R$ is the relation $\delta^\ast$, whose convex closure
yields the product relation $\sigma$ that induces the prime factor
decomposition of connected graphs with respect to the Cartesian product. For
the construction of $\R$ so-called Partial Star Products are of particular
interest. Several special data structures are used that allow to compute
Partial Star Products in constant time. These computations are tuned to the
recognition of approximate graph products, but also lead to a linear time
algorithm for the computation of $\delta^\ast$ for graphs with maximum bounded
degree.
  Furthermore, we define \emph{quasi Cartesian products} as graphs with
non-trivial $\delta^\ast$. We provide several examples, and show that quasi
Cartesian products can be recognized in linear time for graphs with bounded
maximum degree. Finally, we note that quasi products can be recognized in
sublinear time with a parallelized algorithm.


title:
Gaussian error correction of quantum states in a correlated noisy
  channel

abstract:
  Noise is the main obstacle for the realization of fault tolerant quantum
information processing and secure communication over long distances. In this
work, we propose a communication protocol relying on simple linear optics that
optimally protects quantum states from non-Markovian or corre- lated noise. We
implement the protocol experimentally and demonstrate the near ideal protection
of coherent and entangled states in an extremely noisy channel. Since all
real-life channels are exhibit- ing pronounced non-Markovian behavior, the
proposed protocol will have immediate implications in improving the performance
of various quantum information protocols.


title:
Probing the ejecta of evolved massive stars in transition: A VLT/SINFONI
  K-band survey

abstract:
  Massive evolved stars in transition phases, such as Luminous Blue Variables
(LBVs), B[e] Supergiants (B[e]SGs), and Yellow Hypergiants (YHGs), are not well
understood, and yet crucial steps in determining accurate stellar and galactic
evolution models. The circumstellar environments of these stars reveal their
mass-loss history, identifying clues to both their individual evolutionary
status and the connection between objects of different phases. Here we present
a survey of 25 such evolved massive stars (16 B[e]SGs, 6 LBVs, 2 YHGs, and 1
Peculiar Oe star), observed in the K-band with the Spectrograph for INtegral
Field Observation in the Near-Infrared (SINFONI; R = 4500) on the ESO VLT UT4 8
m telescope. The sample can be split into two categories based on spectral
morphology: one group includes all of the B[e]SGs, the Peculiar Oe star, and
two of the LBVs, while the other includes the YHGs and the rest of the LBVs.
The difference in LBV spectral appearance is due to some objects being in a
quiescent phase and some objects being in an active or outburst phase. CO
emission features are found in 13 of our targets, with first time detections
for MWC 137, LHA 120-S 35, and LHA 115-S 65. From model fits to the CO band
heads, the emitting regions appear to be detached from the stellar surface.
Each star with ^12CO features also shows ^13CO emission, signaling an evolved
nature. Based on the level of ^13C enrichment, we conclude that many of the
B[e]SGs are likely in a pre-Red Supergiant phase of their evolution. There
appears to be a lower luminosity limit of log L/L_solar = 5.0 below which CO is
not detected. The lack of CO features in several high luminosity B[e]SGs and
variability in others suggests that they may in fact be LBV candidates,
strengthening the connection between these two very similar transition phases.


title:
Variables suitable for constructing quantum states for the Teleparallel
  Equivalent of General Relativity II

abstract:
  We present the second (and final) part of an analysis aimed at introducing
variables which are suitable for constructing a space of quantum states for the
Teleparallel Equivalent of General Relativity. In the first part of the
analysis we introduced a family of variables on the "position" sector of the
phase space. In this paper we distinguish differentiable variables in the
family. Then we define momenta conjugate to the distinguished variables and
express constraints of the theory in terms of the variables and the momenta.
Finally, we exclude variables which generate an obstacle for further steps of
the Dirac's procedure of canonical quantization of constrained systems we are
going to apply to the theory. As a result we obtain two collections of
variables on the phase space which will be used (in a subsequent paper) to
construct the desired space of quantum states.


title:
Absolute density measurement of SD radicals in a supersonic jet at the
  quantum-noise limit

abstract:
  The absolute density of SD radicals in a supersonic jet has been measured
down to $(1.1\pm0.1)\times10^5$ cm$^{-3}$ in a modestly specified apparatus
that uses a cross-correlated combination of cavity ring-down and laser-induced
fluorescence detection. Such a density corresponds to $215\pm21$ molecules in
the probe volume at any given time. The minimum detectable absorption
coefficient was quantum-noise-limited and measured to be
$(7.9\pm0.6)\times10^{-11}$ cm$^{-1}$, in 200 s of acquisition time,
corresponding to a noise-equivalent absorption sensitivity for the apparatus of
$(1.6\pm0.1)\times10^{-9}$ cm$^{-1}$ Hz$^{-1/2}$.


title:
Hubble Space Telescope hot Jupiter Transmission Spectral Survey:
  detection of water in HAT-P-1b from Wide Field Camera 3 near-infrared spatial
  scan observations

abstract:
  We present Hubble Space Telescope near-infrared transmission spectroscopy of
the transiting hot-Jupiter HAT-P-1b. We observed one transit with Wide Field
Camera 3 using the G141 low-resolution grism to cover the wavelength range
1.087- 1.678 {\mu}m. These time series observations were taken with the newly
available spatial scan mode that increases the duty cycle by nearly a factor of
two, thus improving the resulting photometric precision of the data. We measure
a planet-to-star radius ratio of Rp/R*=0.11709+/-0.00038 in the white light
curve with the centre of transit occurring at 2456114.345+/-0.000133 (JD). We
achieve S/N levels per exposure of 1840 (0.061%) at a resolution of
{\Delta\lambda}=19.2nm (R~70) in the 1.1173 - 1.6549{\mu}m spectral region,
providing the precision necessary to probe the transmission spectrum of the
planet at close to the resolution limit of the instrument. We compute the
transmission spectrum using both single target and differential photometry with
similar results. The resultant transmission spectrum shows a significant
absorption above the 5-{\sigma} level matching the 1.4{\mu}m water absorption
band. In solar composition models, the water absorption is sensitive to the ~1
mbar pressure levels at the terminator. The detected absorption agrees with
that predicted by an 1000 K isothermal model, as well as with that predicted by
a planetary-averaged temperature model.


title:
Genetic information, physical interpreters and thermodynamics; the
  material-informatic basis of biosemiosis

abstract:
  The sequence of nucleotide bases occurring in an organism's DNA is often
regarded as a codescript for its construction. However, information in a DNA
sequence can only be regarded as a codescript relative to an operational
biochemical machine, which the information constrains in such a way as to
direct the process of construction. In reality, any biochemical machine for
which a DNA codescript is efficacious is itself produced through the mechanical
interpretation of an identical or very similar codescript. In these terms the
origin of life can be described as a bootstrap process involving the
simultaneous accumulation of genetic information and the generation of a
machine that interprets it as instructions for its own construction. This
problem is discussed within the theoretical frameworks of thermodynamics,
informatics and self-reproducing automata, paying special attention to the
physico-chemical origin of genetic coding and the conditions, both
thermodynamic and informatic, which a system must fulfil in order for it to
sustain semiosis. The origin of life is equated with biosemiosis


title: The nonexistence of an additive quaternary [15,5,9]-code

abstract:
  We show that no additive [15,5,9]_4-code exists. As a consequence the largest
dimension k such that an additive quaternary [15,k,9]_4-code exists is k=4.5.


title:
Stripe, gossamer, and glassy phases in systems with strong non-pairwise
  interactions

abstract:
  We study structure formation in systems of classical particles in two
dimensions with long-range attractive short-range repulsive two-body
interactions and repulsive three-body interactions. Stripe, gossamer, and glass
phases are found as a result of nonpairwise interaction.


title: Optical tweezers for vortex rings in Bose-Einstein condensates

abstract:
  We study formation and stabilization of vortex rings in atomic Bose-Einstein
condensates. We suggest a novel approach for generating and trapping of vortex
rings by 'optical tweezers'--two blue-detuned optical beams forming a toroidal
void in the bulk of a magnetically or optically confined condensate cloud. We
demonstrate that matter-wave vortex rings trapped within the void are
energetically and dynamically stable. Our theoretical findings suggest the
possibility for generation, stabilization, and nondestructive manipulation of
quantized vortex rings in experimentally feasible trapping configurations.


title: Anisotropic flow of thermal photons as a quark-gluon plasma viscometer

abstract:
  We present state-of-the-art calculations of viscous photon emission from
nuclear collisions at RHIC and LHC. Fluctuating initial density profiles are
evolved with event-by-event viscous hydrodynamics. Momentum spectra of thermal
photons radiated by these explosively expanding fireballs and their
$p_T$-differential anisotropic flow coefficients $v_n(p_T)$ are computed, both
with and without accounting for viscous corrections to the standard thermal
emission rates. Viscous corrections to the rates are found to have a larger
effect on the $v_n$ coefficients than the viscous suppression of hydrodynamic
flow anisotropies. The benefits of taking the ratio of elliptic to triangular
flow, $v_2/v_3$, are discussed, and the spacetime regions which contribute
dominantly to the photon flow harmonics are identified. The directed flow $v_1$
of thermal photons is predicted for RHIC and LHC energies.


title:
Three-body calculation of the Delta-Delta dibaryon candidate D(03) at
  2.37 GeV

abstract:
  The D(03) dibaryon is generated dynamically as a resonance pole in a
pion-nucleon-Delta' three-body model, where Delta' is a stable Delta baryon.
Using separable interactions dominated by the Delta(1232) isobar for
pion-nucleon and by the D(12) isobar for nucleon-Delta', where D(12) is the
nucleon-Delta 2150 MeV dibaryon deduced in and constrained by 1D2 pp
scattering, the model reduces to an effective two-body problem for Delta-Delta'
which is solved. The mass and width of D(03) are found close to those of the
I(JP)=0(3+) resonance peak observed by WASA@COSY in pion-production pn
collisions at 2.37 GeV.


title: On the circumradius condition for piecewise linear triangular elements

abstract:
  We discuss the error analysis of linear interpolation on triangular elements.
We claim that the circumradius condition is more essential then the well-known
maximum angle condition for convergence of the finite element method. Numerical
experiments show that this condition is the best possible.
  We also point out that the circumradius condition is closely related to the
definition of surface area.


title: Extending Romanovski polynomials in quantum mechanics

abstract:
  Some extensions of the (third-class) Romanovski polynomials (also called
Romanovski/pseudo-Jacobi polynomials), which appear in bound-state
wavefunctions of rationally-extended Scarf II and Rosen-Morse I potentials, are
considered. For the former potentials, the generalized polynomials satisfy a
finite orthogonality relation, while for the latter an infinite set of
relations among polynomials with degree-dependent parameters is obtained. Both
types of relations are counterparts of those known for conventional
polynomials. In the absence of any direct information on the zeros of the
Romanovski polynomials present in denominators, the regularity of the
constructed potentials is checked by taking advantage of the disconjugacy
properties of second-order differential equations of Schr\"odinger type. It is
also shown that on going from Scarf I to Scarf II or from Rosen-Morse II to
Rosen-Morse I potentials, the variety of rational extensions is narrowed down
from types I, II, and III to type III only.


title:
Higher-order Cauchy of the first kind and poly-Cauchy of the first kind
  mixed type polynomials

abstract:
  In this paper, we study higher-order Cauchy of the first kind and poly-Cauchy
of the first kind mixed type polynomials with viewpoint of umbral calculus and
give some interesting identities and formulae of those polynomials which are
derived from umbral calculus.


title: MaLeS: A Framework for Automatic Tuning of Automated Theorem Provers

abstract:
  MaLeS is an automatic tuning framework for automated theorem provers. It
provides solutions for both the strategy finding as well as the strategy
scheduling problem. This paper describes the tool and the methods used in it,
and evaluates its performance on three automated theorem provers: E, LEO-II and
Satallax. An evaluation on a subset of the TPTP library problems shows that on
average a MaLeS-tuned prover solves 8.67% more problems than the prover with
its default settings.


title:
Carrier-envelope phase stability of hollow-fibers used for high-energy,
  few-cycle pulse generation

abstract:
  We investigated the carrier-envelope phase (CEP) stability of a hollow-fiber
setup used for high-energy, few-cycle pulse generation. Saturation of the
output pulse energy is observed at 0.6 mJ for a 260 um inner-diameter, 1 m long
fiber, statically filled with neon, with the pressure adjusted to achieve an
output spectrum capable of supporting sub-4fs pulses. The maximum output pulse
energy can be increased to 0.8mJ by using either differential pumping, or
circularly polarized input pulses. We observe the onset of an
ionization-induced CEP instability, which does not increase beyond an input
pulse energy of 1.25 mJ due to losses in the fiber caused by ionization. There
is no significant difference in the CEP stability with differential pumping
compared to static-fill, demonstrating that gas flow in differentially pumped
fibers does not degrade the CEP stabilization.


title: Lie Dimension Subrings

abstract:
  We compare, for L a Lie ring over the integers, its lower central series
(\gamma_n(L))_{n>0} and its dimension series defined by \delta_n(L):=L\cap
\varpi^n(L) in the universal enveloping algebra of L. We show that
\gamma_n(L)=\delta_n(L) for all n<4, but give an example showing that they may
differ if n=4. We introduce simplicial methods to describe these results, and
to serve as a possible tool for further study of the dimension series.


title: Deconstructing analogy

abstract:
  Analogy has been shown to be important in many key cognitive abilities,
including learning, problem solving, creativity and language change. For
cognitive models of analogy, the fundamental computational question is how its
inherent complexity (its NP-hardness) is solved by the human cognitive system.
Indeed, different models of analogical processing can be categorized by the
simplification strategies they adopt to make this computational problem more
tractable. In this paper, I deconstruct several of these models in terms of the
simplification-strategies they use; a deconstruction that provides some
interesting perspectives on the relative differences between them. Later, I
consider whether any of these computational simplifications reflect the actual
strategies used by people and sketch a new cognitive model that tries to
present a closer fit to the psychological evidence.


title:
High order volume preserving integrators for three kinds of
  divergence-free vector fields via commutator

abstract:
  In this paper, we focus on the construction of high order volume preserving
in- tegrators for divergence-free vector fields: the monomial basis, the
exponential basis and tensor product of the monomial and the exponential basis.
We first prove that the commutators of elementary divergence-free vector fields
(EDFVF) of those three kinds are still divergence-free vector fields of the
same kind. Assuming then there is only diagonal part of divergence-free vector
field of the monomial basis, for those three kinds of divergence-free vector
fields, we construct high order volume-preserving inte- grators using the
multi-commutators for EDFVFs. Moreover, we consider the ordering of the EDFVFs
and their commutators to reduce the error of the schemes, showing by numerical
tests that the strategy in [9] works very well.


title:
Electronic transport through ordered and disordered graphene grain
  boundaries

abstract:
  The evolution of electronic wave packets (WPs) through grain boundaries (GBs)
of various structures in graphene was investigated by the numerical solution of
the time-dependent Schroedinger equation. WPs were injected from a simulated
STM tip placed above one of the grains. Electronic structure of the GBs was
calculated by ab-initio and tight-binding methods. Two main factors governing
the energy dependence of the transport have been identified: the misorientation
angle of the two adjacent graphene grains and the atomic structure of the GB.
In case of an ordered GB made of a periodic repetition of pentagon-heptagon
pairs, it was found that the transport at high and low energies is mainly
determined by the misorientation angle, but the transport around the Fermi
energy is correlated with the electronic structure of the GB. A particular line
defect with zero misorientation angle (Lahiri et al, Nat Nanotechnol
2010,5:326) behaves as a metallic nanowire and shows electron-hole asymmetry
for hot electrons or holes. To generate disordered GBs, found experimentally in
CVD graphene samples, a Monte-Carlo-like procedure has been developed. Results
show a reduced transport for the disordered GBs, primarily attributed to
electronic localized states caused by C atoms with only two covalent bonds.


title:
Tropical Fourier-Motzkin elimination, with an application to real-time
  verification

abstract:
  We introduce a generalization of tropical polyhedra able to express both
strict and non-strict inequalities. Such inequalities are handled by means of a
semiring of germs (encoding infinitesimal perturbations). We develop a tropical
analogue of Fourier-Motzkin elimination from which we derive geometrical
properties of these polyhedra. In particular, we show that they coincide with
the tropically convex union of (non-necessarily closed) cells that are convex
both classically and tropically. We also prove that the redundant inequalities
produced when performing successive elimination steps can be dynamically
deleted by reduction to mean payoff game problems. As a complement, we provide
a coarser (polynomial time) deletion procedure which is enough to arrive at a
simply exponential bound for the total execution time. These algorithms are
illustrated by an application to real-time systems (reachability analysis of
timed automata).


title: The Control of Branching Morphogenesis

abstract:
  Many organs of higher organisms are heavily branched structures and arise by
an at first sight similar process of branching morphogenesis. Yet the
regulatory components and local interactions that have been identified differ
greatly in these organs. It is an open question whether the regulatory
processes work according to a common principle and in how far physical and
geometric constraints determine the branching process. Here we review the known
regulatory factors and physical constraints in lung, kidney, pancreas,
prostate, mammary and salivary gland branching morphogenesis, and describe the
models that have been formulated to analyse their impacts.


title: Space as an invention of biological organisms

abstract:
  The question of the nature of space around us has occupied thinkers since the
dawn of humanity, with scientists and philosophers today implicitly assuming
that space is something that exists objectively. Here we show that this does
not have to be the case: the notion of space could emerge when biological
organisms seek an economic representation of their sensorimotor flow. The
emergence of spatial notions does not necessitate the existence of real
physical space, but only requires the presence of sensorimotor invariants
called `compensable' sensory changes. We show mathematically and then in
simulations that na\"ive agents making no assumptions about the existence of
space are able to learn these invariants and to build the abstract notion that
physicists call rigid displacement, which is independent of what is being
displaced. Rigid displacements may underly perception of space as an unchanging
medium within which objects are described by their relative positions. Our
findings suggest that the question of the nature of space, currently exclusive
to philosophy and physics, should also be addressed from the standpoint of
neuroscience and artificial intelligence.


title:
Detection of antiferromagnetic ordering in heavily doped LaFeAsO1-xHx
  pnictide superconductors using nuclear-magnetic-resonance techniques

abstract:
  We studied double superconducting (SC) domes in LaFeAsO1-xHx by using 75As-
and 1H-nuclear magnetic resonance techniques, and unexpectedly discovered that
a new antiferromagnetic (AF) phase follows the double SC domes on further H
doping, forming a symmetric alignment of AF and SC phases in the electronic
phase diagram. We demonstrated that the new AF ordering originates from the
nesting between electron pockets, unlike the nesting between electron and hole
pockets as seen in the majority of undoped pnictides. The new AF ordering is
derived from the features common to high-Tc pnictides: however, it has not been
reported so far for other high-Tc pnictides because of their poor electron
doping capability.


title: Classification of certain continuous fields of Kirchberg algebras

abstract:
  We show that the K-theory cosheaf is a complete invariant for separable
continuous fields with vanishing boundary maps over a finite-dimensional
compact metrizable topological space whose fibers are stable Kirchberg algebras
with rational K-theory groups satisfying the universal coefficient theorem. We
provide a range result for fields in this class with finite-dimensional
K-theory. There are versions of both results for unital continuous fields.


title: Topological entropy of minimal geodesics and volume growth on surfaces

abstract:
  Let (M,g) be a compact Riemannian manifold of hyperbolic type, i.e M is a
manifold admitting another metric of strictly negative curvature. In this paper
we study the geodesic flow restricted to the set of geodesics which are minimal
on the universal covering. In particular for surfaces we show that the
topological entropy of the minimal geodesics coincides with the volume entropy
of (M, g) generalizing work of Freire and Mane.


title:
The contact property for nowhere vanishing magnetic fields on the
  two-sphere

abstract:
  In this paper we give some positive and negative results about the contact
property for the energy levels $\Sigma_c$ of a symplectic magnetic field on
$S^2$. In the first part we focus on the case of the area form on a surface of
revolution. We state a sufficient condition for an energy level to be of
contact type and give an example where the contact property fails. If the
magnetic curvature is positive, the dynamics and the action of invariant
measures can be numerically computed. This hints at the conjecture that an
energy level of a symplectic magnetic field with positive magnetic curvature
should be of contact type. In the second part we show that, for small energies,
there exists a convex hypersurface $N_c$ in $\mathbb C^2$ and a covering map
$p_c:N_c \rightarrow \Sigma_c$ such that the pull-back via $p_c$ of the
characteristic distribution on $\Sigma_c$ is the standard characteristic
distribution on $N_c$. As a corollary we prove that there are either two or
infinitely many periodic orbits on $\Sigma_c$. The second alternative holds if
there exists a contractible prime periodic orbit.


title:
Yukawaon Model with Anomaly Free Set of Quarks and Leptons in a U(3)
  Family Symmetry

abstract:
  In the so-called "yukawaon" model, the (effective) Yukawa coupling constants
$Y_f^{eff}$ are given by vacuum expectation values (VEVs) of scalars $Y_f$
(yukawaons) with $3\times 3$ components. So far, yukawaons $Y_f$ have been
assigned to ${\bf 6}$ or ${\bf 6}^*$ of U(3) family symmetry, so that quarks
and leptons were not anomaly free in U(3). In this paper, yukawaons are
assigned to ${\bf 8}+{\bf 1}$ of U(3), so that quarks and leptons are anomaly
free. Since VEV relations among yukawaons are also considerably changed,
parameter fitting of the model is renewed. After fixing our free parameters by
observed mass ratios, we have only two and one remaining free parameters for
quark and lepton mixings, respectively. We obtain successful predictions for
the quark and lepton mixing parameters including magnitudes of $CP$ violation.
The effective Majorana neutrino mass is also predicted.


title: Multi-pomeron repulsion and the Neutron-star mass

abstract:
  A multi-pomeron exchange potential (MPP) is proposed as a model for the
three-body repulsion indicated in neutron-star matter, which works universally
among three- and four-baryons. Its strength is determined by analyzing the
nucleus-nucleus scattering with the G-matrix folding model. The EoS in neutron
matter is obtained including the MPP contribution. The neutron-star mass is
calculated by solving the TOV equation. The maximum mass is obtained to be
larger than the observed one $1.97 M_{solar}$ on the basis of the experimental
data.


title:
Optomechanics with Cavity Polaritons: Dissipative Coupling and
  Unconventional Bistability

abstract:
  We study a hybrid system formed from an optomechanical resonator and a cavity
mode strongly coupled to an excitonic transition inside a quantum well. We show
that due to the mixing of cavity photon and exciton states, the emergent
quasiparticles - polaritons - possess coupling to the mechanical mode of both
dispersive and dissipative nature. We calculate the occupancies of polariton
modes and reveal bistable behavior, which deviates from conventional Kerr
nonlinearity or dispersive coupling cases due to the dissipative coupling. The
described system serves as a good candidate for future polaritonic devices and
solid state quantum information processing.


title: On periodically driven AdS/CFT

abstract:
  We use the AdS/CFT correspondence to study a thermally isolated conformal
field theory in four dimensions which undergoes a repeated deformation by an
external periodic time-dependent source coupled to an operator of dimension
Delta. The initial state of the theory is taken to be at a finite temperature.
We compute the energy dissipated in the system as a function of the frequency
and of the dimension Delta of the perturbing operator. This is done in the
linear response regime. In order to study the details of thermalization in the
dual field theory, the leading-order backreaction on the AdS black brane metric
is computed. The evolution of the event and the apparent horizons is monitored;
the increase of area in each cycle coincides with the increase in the
equilibrium entropy corresponding to the amount of energy dissipated. The time
evolution of the entanglement entropy of a spherical region and that of the
two-points function of a probe operator with a large dimension are also
inspected; we find a delay in the thermalization of these quantities which is
proportional to the size of the region which is being probed. Thus, the delay
is more pronounced in the infrared. We comment on a possible transition in the
time evolution of the energy fluctuations.


title: Three-nucleon forces in exotic open-shell isotopes

abstract:
  Advances in the self-consistent Green's function approach to finite nuclei
are discussed, including the implementation of three-nucleon forces and the
extension to the Gorkov formalism. We report results on binding energies in the
nitrogen and fluorine isotopic chains, as well as spectral functions of 22O.
The application to medium-mass open-shell systems is illustrated by separation
energy spectra of two argon isotopes, which are compared to one-neutron removal
experiments.


title:
Predicting genome-wide DNA methylation using methylation marks, genomic
  position, and DNA regulatory elements

abstract:
  Background: Recent assays for individual-specific genome-wide DNA methylation
profiles have enabled epigenome-wide association studies to identify specific
CpG sites associated with a phenotype. Computational prediction of CpG
site-specific methylation levels is important, but current approaches tackle
average methylation within a genomic locus and are often limited to specific
genomic regions. Results: We characterize genome-wide DNA methylation patterns,
and show that correlation among CpG sites decays rapidly, making predictions
solely based on neighboring sites challenging. We built a random forest
classifier to predict CpG site methylation levels using as features neighboring
CpG site methylation levels and genomic distance, and co-localization with
coding regions, CGIs, and regulatory elements from the ENCODE project, among
others. Our approach achieves 91% -- 94% prediction accuracy of genome-wide
methylation levels at single CpG site precision. The accuracy increases to 98%
when restricted to CpG sites within CGIs. Our classifier outperforms
state-of-the-art methylation classifiers and identifies features that
contribute to prediction accuracy: neighboring CpG site methylation status, CpG
island status, co-localized DNase I hypersensitive sites, and specific
transcription factor binding sites were found to be most predictive of
methylation levels. Conclusions: Our observations of DNA methylation patterns
led us to develop a classifier to predict site-specific methylation levels that
achieves the best DNA methylation predictive accuracy to date. Furthermore, our
method identified genomic features that interact with DNA methylation,
elucidating mechanisms involved in DNA methylation modification and regulation,
and linking different epigenetic processes.


title: The dynamics of alternative pathways to compensatory substitution

abstract:
  The role of epistatic interactions among loci is a central question in
evolutionary biology and is increasingly relevant in the genomic age. While the
population genetics of compensatory substitution have received considerable
attention, most studies have focused on the case when natural selection is very
strong against deleterious intermediates. In the biologically-plausible
scenario of weak to moderate selection there exist two alternate pathways for
compensatory substitution. In one pathway, a deleterious mutation becomes fixed
prior to occurrence of the compensatory mutation. In the other, the two loci
are simultaneously polymorphic. The rates of compensatory substitution along
these two pathways and their relative probabilities are functions of the
population size, selection strength, mutation rate, and recombination rate. In
this paper these rates and path probabilities are derived analytically and
verified using population genetic simulations. The expected time durations of
these two paths are similar when selection is moderate, but not when selection
is weak. The effect of recombination on the dynamics of the substitution
process are explored using simulation. Using the derived rates, a phylogenetic
substitution model of the compensatory evolution process is presented that
could be used for inference of population genetic parameters from interspecific
data.


title:
Behavior of Gaussian curvature and mean curvature near non-degenerate
  singular points on wave fronts

abstract:
  We define cuspidal curvature $\kappa_c$ (resp. normalized cuspidal curvature
$\mu_c$) along cuspidal edges (resp. at swallowtail singularity) in Riemannian
$3$-manifolds, and show that it gives a coefficient of the divergent term of
the mean curvature function. Moreover, we show that the product $\kappa_\Pi$
called the product curvature (resp. $\mu_\Pi$ called normalized product
curvature) of $\kappa_c$ (resp. $\mu_c$) and the limiting normal curvature
$\kappa_\nu$ is an intrinsic invariant of the surface, and is closely related
to the boundedness of the Gaussian curvature. We also consider the limiting
behavior of $\kappa_\Pi$ when cuspidal edges accumulate to other singularities.
Moreover, several new geometric invariants of cuspidal edges and swallowtails
are given.


title:
The cooling of the Cassiopeia A neutron star as a probe of the nuclear
  symmetry energy and nuclear pasta

abstract:
  X-ray observations of the neutron star in the Cas A supernova remnant over
the past decade suggest the star is undergoing a rapid drop in surface
temperature of $\approx$ $2-5.5\%$. One explanation suggests the rapid cooling
is triggered by the onset of neutron superfluidity in the core of the star,
causing enhanced neutrino emission from neutron Cooper pair breaking and
formation (PBF). Using consistent neutron star crust and core equations of
state (EOSs) and compositions, we explore the sensitivity of this
interpretation to the density dependence of the symmetry energy $L$ of the EOS
used, and to the presence of enhanced neutrino cooling in the bubble phases of
crustal "nuclear pasta". Modeling cooling over a conservative range of neutron
star masses and envelope compositions, we find $L\lesssim70$ MeV, competitive
with terrestrial experimental constraints and other astrophysical observations.
For masses near the most likely mass of $M\gtrsim 1.65 M_{\odot}$, the
constraint becomes more restrictive $35\lesssim L\lesssim 55$ MeV. The
inclusion of the bubble cooling processes decreases the cooling rate of the
star during the PBF phase, matching the observed rate only when $L\lesssim45$
MeV, taking all masses into consideration, corresponding to neutron star radii
$\lesssim 11$km.


title:
Two-loop QED corrections with closed fermion loops for the
  bound-electron g factor

abstract:
  Two-loop QED corrections with closed fermion loops are calculated for the 1s
bound-electron g factor. Calculations are performed to all orders in the
nuclear binding strength parameter Z\alpha (where Z is the nuclear charge and
\alpha is the fine structure constant) except for the closed fermion loop,
which is treated within the free-loop (Uehling) approximation in some cases.
Comparison with previous Z\alpha-expansion calculations is made and the
higher-order remainder of order \alpha^2(Z\alpha)^5 and higher is separated out
from the numerical results.


title: Fractional Klein-Gordon equations and related stochastic processes

abstract:
  This paper presents finite-velocity random motions driven by fractional
Klein-Gordon equations of order $\alpha \in (0,1]$. A key tool in the analysis
is played by the McBride's theory which converts fractional hyper-Bessel
operators into Erdelyi-Kober integral operators. Special attention is payed to
the fractional telegraph process whose space-dependent distribution solves a
non-homogeneous fractional Klein-Gordon equation. The distribution of the
fractional telegraph process for $\alpha = 1$ coincides with that of the
classical telegraph process and its driving equation converts into the
homogeneous Klein-Gordon equation. Fractional planar random motions at finite
velocity are also investigated, the corresponding distributions obtained as
well as the explicit form of the governing equations. Fractionality is
reflected into the underlying random motion because in each time interval a
binomial number of deviations $B(n,\alpha)$ (with uniformly-distributed
orientation) are considered. The parameter $n$ of $B(n,\alpha)$ is itself a
random variable with fractional Poisson distribution, so that fractionality
acts as a subsampling of the changes of directions. Finally the behaviour of
each coordinate of the planar motion is examined and the corresponding
densities obtained. Extensions to $N$-dimensional fractional random flights are
envisaged as well as the fractional counterpart of the Euler-Poisson-Darboux
equation to which our theory applies.


title: Axioms for Centrality

abstract:
  Given a social network, which of its nodes are more central? This question
has been asked many times in sociology, psychology and computer science, and a
whole plethora of centrality measures (a.k.a. centrality indices, or rankings)
were proposed to account for the importance of the nodes of a network. In this
paper, we try to provide a mathematically sound survey of the most important
classic centrality measures known from the literature and propose an axiomatic
approach to establish whether they are actually doing what they have been
designed for. Our axioms suggest some simple, basic properties that a
centrality measure should exhibit.
  Surprisingly, only a new simple measure based on distances, harmonic
centrality, turns out to satisfy all axioms; essentially, harmonic centrality
is a correction to Bavelas's classic closeness centrality designed to take
unreachable nodes into account in a natural way.
  As a sanity check, we examine in turn each measure under the lens of
information retrieval, leveraging state-of-the-art knowledge in the discipline
to measure the effectiveness of the various indices in locating web pages that
are relevant to a query. While there are some examples of this comparisons in
the literature, here for the first time we take into consideration centrality
measures based on distances, such as closeness, in an information-retrieval
setting. The results match closely the data we gathered using our axiomatic
approach.
  Our results suggest that centrality measures based on distances, which have
been neglected in information retrieval in favour of spectral centrality
measures in the last years, are actually of very high quality; moreover,
harmonic centrality pops up as an excellent general-purpose centrality index
for arbitrary directed graphs.


title:
The Hour-Glass Magnetic Spectrum Arising from a Striped, Cluster Spin
  Glass Ground State in La1.75Sr0.25CoO4

abstract:
  We report inelastic neutron scattering results that reveal an hour-glass
magnetic excitation spectrum in La1.75Sr0.25CoO4. The magnetic spectrum is
similar to that observed previously in La1.67Sr0.33CoO4, but the spectral
features are broader. We show that the spectrum of La1.75Sr0.25CoO4 can be
modeled by the spin dynamics of a system with a disordered cluster spin glass
ground state. Bulk magnetization measurements are presented which support the
proposed glassy ground state. The observations reiterate the importance of
quasi-one-dimensional magnetic correlations and disorder for the hour-glass
spectrum, and suggest that disordered spin and charge stripes exist at lower
doping in La2-xSrxCoO4 than previously thought.


title: Some notes on model rotation

abstract:
  Model rotation is an efficient technique for improving MUS finding
algorithms. In previous work we have studied model rotation as an algorithm
that traverses a graph which is induced by the input formula. This document
introduces the notion of blocked edges, which are edges in this graph that can
never be traversed. We show the existence of irredundant CNF formulas in which
some clauses are unreachable by model rotation. Additionally, we proof a
conjecture by Belov, Lynce and Marques-Silva.


title: Muon Collider Higgs Factory for Snowmass 2013

abstract:
  We propose the construction of, and describe in detail, a compact Muon
Collider s-channel Higgs Factory.

categories: hep-ph hep-ex physics.acc-ph physics.ins-det


title:
In-Core Computation of Geometric Centralities with HyperBall: A Hundred
  Billion Nodes and Beyond

abstract:
  Given a social network, which of its nodes are more central? This question
has been asked many times in sociology, psychology and computer science, and a
whole plethora of centrality measures (a.k.a. centrality indices, or rankings)
were proposed to account for the importance of the nodes of a network. In this
paper, we approach the problem of computing geometric centralities, such as
closeness and harmonic centrality, on very large graphs; traditionally this
task requires an all-pairs shortest-path computation in the exact case, or a
number of breadth-first traversals for approximated computations, but these
techniques yield very weak statistical guarantees on highly disconnected
graphs. We rather assume that the graph is accessed in a semi-streaming
fashion, that is, that adjacency lists are scanned almost sequentially, and
that a very small amount of memory (in the order of a dozen bytes) per node is
available in core memory. We leverage the newly discovered algorithms based on
HyperLogLog counters, making it possible to approximate a number of geometric
centralities at a very high speed and with high accuracy. While the application
of similar algorithms for the approximation of closeness was attempted in the
MapReduce framework, our exploitation of HyperLogLog counters reduces
exponentially the memory footprint, paving the way for in-core processing of
networks with a hundred billion nodes using "just" 2TiB of RAM. Moreover, the
computations we describe are inherently parallelizable, and scale linearly with
the number of available cores.


title:
Universal distribution of component frequencies in biological and
  technological systems

abstract:
  Bacterial genomes and large-scale computer software projects both consist of
a large number of components (genes or software packages) connected via a
network of mutual dependencies. Components can be easily added or removed from
individual systems and their usage frequencies vary over many orders of
magnitude. We study this frequency distribution in genomes of ~500 bacterial
species and in over 2 million of Linux computers and find that in both cases it
is described by the same scale-free power law distribution with an additional
peak near the tail of the distribution corresponding to nearly universal
components. We argue that this is a general property of any modular system with
a multi-layered dependency network. We demonstrate that the frequency of a
component is positively correlated with its dependency degree given by the
total number of upstream components whose operation directly or indirectly
depends on the selected component. The observed frequency/dependency degree
distributions are reproduced in a simple mathematically tractable model
introduced and analyzed in this study.


title: Quantum benchmarks for pure single-mode Gaussian states

abstract:
  Teleportation and storage of continuous variable states of light and atoms
are essential building blocks for the realization of large scale quantum
networks. Rigorous validation of these implementations require identifying, and
surpassing, benchmarks set by the most effective strategies attainable without
the use of quantum resources. Such benchmarks have been established for special
families of input states, like coherent states and particular subclasses of
squeezed states. Here we solve the longstanding problem of defining quantum
benchmarks for general pure Gaussian single-mode states with arbitrary phase,
displacement, and squeezing, randomly sampled according to a realistic prior
distribution. As a special case, we show that the fidelity benchmark for
teleporting squeezed states with totally random phase and squeezing degree is
1/2, equal to the corresponding one for coherent states. We discuss the use of
entangled resources to beat the benchmarks in experiments.

categories: quant-ph cond-mat.quant-gas math-ph math.MP physics.data-an physics.optics


title:
Exploiting Locality in Lease-Based Replicated Transactional Memory via
  Task Migration

abstract:
  We present Lilac-TM, the first locality-aware Distributed Software
Transactional Memory (DSTM) implementation. Lilac-TM is a fully decentralized
lease-based replicated DSTM. It employs a novel self- optimizing lease
circulation scheme based on the idea of dynamically determining whether to
migrate transactions to the nodes that own the leases required for their
validation, or to demand the acquisition of these leases by the node that
originated the transaction. Our experimental evaluation establishes that
Lilac-TM provides significant performance gains for distributed workloads
exhibiting data locality, while typically incurring no overhead for non-data
local workloads.


title:
Surface plasmon resonances of protein-conjugated gold nanoparticles on
  graphitic substrates

abstract:
  We present theoretical calculations for the absorption properties of
protein-coated gold nanoparticles on graphene and graphite substrates. As the
substrate is far away from nanoparticles, numerical results show that the
number of protein bovine serum molecules molecules aggregating on gold surfaces
can be quantitatively determined for gold nanoparticles with arbitrary size by
means of the Mie theory and the absorption spectra. The presence of graphitic
substrate near protein-conjugated gold nanoparticles substantially enhances the
red shift of the surface plasmon resonances of the nanoparticles. Our findings
show that graphene and graphite provide the same absorption band when the
distance between the nanoparticles and the substrate is large. However at
shorter distances, the resonant wavelength peak of graphene-particle system
differs from that of graphite-particle system. Furthermore, the influence of
the chemical potential of graphene on the optical spectra is also investigated.


title:
Frameworks for Reasoning about Syntax that Utilize Quotation and
  Evaluation

abstract:
  It is often useful, if not necessary, to reason about the syntactic structure
of an expression in an interpreted language (i.e., a language with a
semantics). This paper introduces a mathematical structure called a syntax
framework that is intended to be an abstract model of a system for reasoning
about the syntax of an interpreted language. Like many concrete systems for
reasoning about syntax, a syntax framework contains a mapping of expressions in
the interpreted language to syntactic values that represent the syntactic
structures of the expressions; a language for reasoning about the syntactic
values; a mechanism called quotation to refer to the syntactic value of an
expression; and a mechanism called evaluation to refer to the value of the
expression represented by a syntactic value. A syntax framework provides a
basis for integrating reasoning about the syntax of the expressions with
reasoning about what the expressions mean. The notion of a syntax framework is
used to discuss how quotation and evaluation can be built into a language and
to define what quasiquotation is. Several examples of syntax frameworks are
presented.


title:
GeneZip: A software package for storage-efficient processing of genotype
  data

abstract:
  Genome wide association studies directly assay 10^6 single nucleotide
polymorphisms (SNPs) across a study cohort. Probabilistic estimation of
additional sites by genotype imputation can increase this set of variants by
10- to 40-fold. Even with modest sample sizes (10^3-10^4), these resulting
imputed datasets, containing 10^10-10^11 double-precision values, are
incompatible with simultaneous lossless storage in RAM using standard methods.
Existing solutions for this problem require compromises in either genotype
accuracy or complexity of permissible statistical methods. Here, we present a
C/C++ library that dynamically compresses probabilistic genotype data as they
are loaded into memory. This method uses a customization of the DEFLATE (gzip)
algorithm, and maintains constant-time access to any SNP. Average compression
ratios of more than 9-fold are observed in test data.


title:
Probing TeV Left-Right Seesaw at Energy and Intensity Frontiers: a
  Snowmass White Paper

abstract:
  We discuss ways to probe the origin of neutrino masses at the Energy and
Intensity frontiers, in TeV-scale left-right seesaw models where small neutrino
masses arise via type-I seesaw mechanism. We consider generic ('vanilla')
version of such models as well as a version which leads to 'large' light-heavy
neutrino mixing while keeping the neutrino masses small in a natural manner. We
point out specific observable implications of these classes of models at the
LHC as well as in searches for lepton flavor violating processes such as
$\mu\to e\gamma$ and $\mu\to 3e$, and also in searches for lepton number
violating neutrinoless double beta decay.


title: Intervention in Ornstein-Uhlenbeck SDEs

abstract:
  We introduce a notion of intervention for stochastic differential equations
and a corresponding causal interpretation. For the case of the
Ornstein-Uhlenbeck SDE, we show that the SDE resulting from a simple type of
intervention again is an Ornstein-Uhlenbeck SDE. We discuss criteria for the
existence of a stationary distribution for the solution to the intervened SDE.
We illustrate the effect of interventions by calculating the mean and variance
in the stationary distribution of an intervened process in a particularly
simple case.


title:
Supersymmetry with Light Dark Matter confronting the recent CDMS and LHC
  Results

abstract:
  We revisit MSSM scenarios with light neutralino as a dark matter candidate in
view of the latest LHC and dark matter direct and indirect detection
experiments. We show that scenarios with a very light neutralino (~ 10 GeV) and
a scalar bottom quark close in mass, can satisfy all the available constraints
from LEP, Tevatron, LHC, flavour and low energy experiments and provide
solutions in agreement with the bulk of dark matter direct detection
experiments, and in particular with the recent CDMS results.


title:
An elementary proof that the first hitting time of an $F_\sigma$ set by
  a jump process is a stopping time

abstract:
  We give a short and elementary proof that the first hitting time of a
$F_\sigma$ set by the jump process of a c\`{a}dl\`{a}g adapted process is a
stopping time.


title: Imaging the Electron-Boson Coupling in Superconducting FeSe

abstract:
  Scanning tunneling spectroscopy has been used to reveal signatures of a
bosonic mode in the local quasiparticle density of states of superconducting
FeSe films. The mode appears below Tc as a 'dip-hump' feature at energy \Omega
~ 4.7 kBTc beyond the superconducting gap \Delta. Spectra on strained regions
of the FeSe films reveal simultaneous decreases in \Delta and \Omega. This
contrasts with all previous reports on other high-Tc superconductors, where
\Delta locally anti-correlates with \Omega. A local strong coupling model is
found to reconcile the discrepancy well, and to provide a unified picture of
the electron-boson coupling in unconventional superconductors.


title:
A short proof for the Descartes-Frenicle-Sorli conjecture on odd perfect
  numbers

abstract:
  If $N={q^k}{n^2}$ is an odd perfect number given in Eulerian form, then the
Descartes-Frenicle-Sorli conjecture predicts that $k=\nu_{q}(N)=1$. In this
article, we give a short proof for this conjecture.


title: Perturbative Corrections to Kahler Moduli Spaces

abstract:
  We propose a general formula for perturbative-in-alpha' corrections to the
Kahler potential on the quantum Kahler moduli space of Calabi-Yau n-folds, for
any n, in their asymptotic large volume regime. The knowledge of such
perturbative corrections provides an important ingredient needed to analyze the
full structure of this Kahler potential, including nonperturbative corrections
such as the Gromov-Witten invariants of the Calabi-Yau n-folds. We argue that
the perturbative corrections take a universal form, and we find that this form
is encapsulated in a specific additive characteristic class of the Calabi-Yau
n-fold which we call the log Gamma class, and which arises naturally in a
generalization of Mukai's modified Chern character map. Our proposal is
inspired heavily by the recent observation of an equality between the partition
function of certain supersymmetric, two-dimensional gauge theories on a
two-sphere, and the aforementioned Kahler potential. We further strengthen our
proposal by comparing our findings on the quantum Kahler moduli space to the
complex structure moduli space of the corresponding mirror Calabi-Yau geometry.


title:
On the Theory of Self-Adjoint Extensions of the Laplace-Beltrami
  Operator, Quadratic Forms and Symmetry

abstract:
  The main objective of this dissertation is to analyse thoroughly the
construction of self-adjoint extensions of the Laplace-Beltrami operator
defined on a compact Riemannian manifold with boundary and the role that
quadratic forms play to describe them. Moreover, we want to emphasise the role
that quadratic forms can play in the description of quantum systems. A
characterisation of the self-adjoint extensions of the Laplace-Beltrami
operator in terms of unitary operators acting on the Hilbert space at the
boundary is given. Using this description we are able to characterise a wide
class of self-adjoint extensions that go beyond the usual ones, i.e. Dirichlet,
Neumann, Robin,.. and that are semi-bounded below. A numerical scheme to
compute the eigenvalues and eigenvectors in any dimension is proposed and its
convergence is proved. The role of invariance under the action of symmetry
groups is analysed in the general context of the theory of self-adjoint
extensions of symmetric operators and in the context of closed quadratic forms.
The self-adjoint extensions possessing the same invariance than the symmetric
operator that they extend are characterised in the most abstract setting. The
case of the Laplace-Beltrami operator is analysed also in this case. Finally, a
way to generalise Kato's representation theorem for not semi-bounded, closed
quadratic forms is proposed.

categories: math-ph math.FA math.MP math.NA math.SP quant-ph


title: Hawking radiation with dispersion versus breakdown of WKB

abstract:
  Inspired by the condensed matter analogues of black holes (a.k.a. dumb
holes), we study Hawking radiation in the presence of a modified dispersion
relation which becomes super-luminal at large wave-numbers. In the usual
stationary coordinates $(t,x)$, one can describe the asymptotic evolution of
the wave-packets in WKB, but this WKB approximation breaks down in the vicinity
of the horizon, thereby allowing for a mixing between initial and final
creation and annihilation operators. Thus, one might be tempted to identify
this point where WKB breaks down with the moment of particle creation. However,
using different coordinates $(\tau,U)$, we find that one can evolve the waves
so that WKB in these coordinates is valid throughout this transition region --
which contradicts the above identification of the breakdown of WKB as the cause
of the radiation. Instead, our analysis suggests that the tearing apart of the
waves into two different asymptotic regions (inside and outside the horizon) is
the major ingredient of Hawking radiation.


title: Taylor Expansion Proof of the Matrix Tree Theorem - Part II

abstract:
  The All Minors Matrix Tree Theorem states that the determinant of any
submatrix of a matrix whose columns sum to zero can be computed as a sum over
certain oriented forests. We offer a particularly short proof of this result,
which amounts to comparing Taylor series expansions.


title: Etched graphene quantum dots on hexagonal boron nitride

abstract:
  We report on the fabrication and characterization of etched graphene quantum
dots (QDs) on hexagonal boron nitride (hBN) and SiO2 with different island
diameters. We perform a statistical analysis of Coulomb peak spacings over a
wide energy range. For graphene QDs on hBN, the standard deviation of the
normalized peak spacing distribution decreases with increasing QD diameter,
whereas for QDs on SiO2 no diameter dependency is observed. In addition, QDs on
hBN are more stable under the influence of perpendicular magnetic fields up to
9T. Both results indicate a substantially reduced substrate induced disorder
potential in graphene QDs on hBN.


title: Approximate cone factorizations and lifts of polytopes

abstract:
  In this paper we show how to construct inner and outer convex approximations
of a polytope from an approximate cone factorization of its slack matrix. This
provides a robust generalization of the famous result of Yannakakis that
polyhedral lifts of a polytope are controlled by (exact) nonnegative
factorizations of its slack matrix. Our approximations behave well under
polarity and have efficient representations using second order cones. We
establish a direct relationship between the quality of the factorization and
the quality of the approximations, and our results extend to generalized slack
matrices that arise from a polytope contained in a polyhedron.


title: Concerning Kurosaki's squarefree word

abstract:
  In 2008, Kurosaki gave a new construction of a (bi-)infinite squarefree word
over three letters. We show that in fact Kurosaki's word avoids 7/4+-powers,
which, as shown by Dejean, is optimal over a 3-letter alphabet.


title:
Superfluid Optomechanics: Coupling of a Superfluid to a Superconducting
  Condensate

abstract:
  We investigate the low loss acoustic motion of superfluid $^4$He
parametrically coupled to a very low loss, superconducting Nb, TE$_{011}$
microwave resonator, forming a gram-scale, sideband resolved, optomechanical
system. We demonstrate the detection of a series of acoustic modes with quality
factors as high as $7\cdot 10^6$. At higher temperatures, the lowest
dissipation modes are limited by an intrinsic three phonon process. Acoustic
quality factors approaching $10^{11}$ may be possible in isotopically purified
samples at temperatures below 10 mK. A system of this type may be utilized to
study macroscopic quantized motion and as an ultra-sensitive sensor of
extremely weak displacements and forces, such as continuous gravity wave
sources.


title: Exciton-Trion Coherent Interactions in a CdTe/CdMgTe Quantum Well

abstract:
  We present a collection of zero-, one- and two-quantum two-dimensional
coherent spectra of excitons and trions in a CdTe/(Cd,Mg)Te quantum well. The
set of spectra provides a unique and comprehensive picture of the exciton and
trion nonlinear optical response. Exciton-exciton and exciton-trion coherent
coupling is manifest as distinct peaks in the spectra, whereas signatures of
trion-trion interactions are absent. Excellent agreement using density matrix
calculations is obtained, which highlights the essential role of many-body
effects on coherent interactions in the quantum well.


title: Parallel Triangle Counting in Massive Streaming Graphs

abstract:
  The number of triangles in a graph is a fundamental metric, used in social
network analysis, link classification and recommendation, and more. Driven by
these applications and the trend that modern graph datasets are both large and
dynamic, we present the design and implementation of a fast and cache-efficient
parallel algorithm for estimating the number of triangles in a massive
undirected graph whose edges arrive as a stream. It brings together the
benefits of streaming algorithms and parallel algorithms. By building on the
streaming algorithms framework, the algorithm has a small memory footprint. By
leveraging the paralell cache-oblivious framework, it makes efficient use of
the memory hierarchy of modern multicore machines without needing to know its
specific parameters. We prove theoretical bounds on accuracy, memory access
cost, and parallel runtime complexity, as well as showing empirically that the
algorithm yields accurate results and substantial speedups compared to an
optimized sequential implementation.
  (This is an expanded version of a CIKM'13 paper of the same title.)