title: Origin of magnetism and quasiparticles properties in Cr-doped TiO$_2$

abstract:
  Combining LSDA+$U$ and an analysis of superexchange interactions beyond DFT,
we describe the magnetic ground states in rutile and anatase Cr-doped TiO$_2$.
In parallel, we correct our LSDA+$U$ ground state through GW corrections
($GW$@LSDA+$U$) that reproduce the position of impurity states and the band
gaps in satisfying agreement with experiments. Because of the different
topological coordinations of Cr-Cr bonds in the ground states of rutile and
anatase, superexchange interactions induce either ferromagnetic or
antiferromagnetic couplings of Cr ions. In Cr-doped anatase, this interaction
leads to a new mechanism which stabilizes a ferromagnetic ground state, in
keeping with experimental evidence, without the need to invoke F-center
exchange.


title:
Fast Matching by 2 Lines of Code for Large Scale Face Recognition
  Systems

abstract:
  In this paper, we propose a method to apply the popular cascade classifier
into face recognition to improve the computational efficiency while keeping
high recognition rate. In large scale face recognition systems, because the
probability of feature templates coming from different subjects is very high,
most of the matching pairs will be rejected by the early stages of the cascade.
Therefore, the cascade can improve the matching speed significantly. On the
other hand, using the nested structure of the cascade, we could drop some
stages at the end of feature to reduce the memory and bandwidth usage in some
resources intensive system while not sacrificing the performance too much. The
cascade is learned by two steps. Firstly, some kind of prepared features are
grouped into several nested stages. And then, the threshold of each stage is
learned to achieve user defined verification rate (VR). In the paper, we take a
landmark based Gabor+LDA face recognition system as baseline to illustrate the
process and advantages of the proposed method. However, the use of this method
is very generic and not limited in face recognition, which can be easily
generalized to other biometrics as a post-processing module. Experiments on the
FERET database show the good performance of our baseline and an experiment on a
self-collected large scale database illustrates that the cascade can improve
the matching speed significantly.


title:
Population synthesis of ultracompact X-ray binaries in the Galactic
  Bulge

abstract:
  [abridged] Aims. We model the number and properties of ultracompact X-ray
binaries (UCXBs) in the Galactic Bulge. The objective is to learn about the
formation of UCXBs and their evolution, such as the onset of mass transfer and
late-time behavior. Methods. The binary population synthesis code SeBa and
stellar evolutionary tracks are used to model the UCXB population. The
luminosity behavior of UCXBs is predicted using long-term X-ray observations of
the known UCXBs and the thermal-viscous disk instability model. Results. In our
model, the majority of UCXBs initially have a helium burning star donor. In the
absence of a mechanism that destroys old UCXBs, we predict (0.2 - 1.9) x 10^5
UCXBs in the Galactic Bulge, mostly at orbital periods longer than 60 min (a
large number of long-period systems also follows from the observed short-period
UCXB population). About 5 - 50 UCXBs should be brighter than 10^35 erg/s,
mostly persistent sources with orbital periods shorter than 30 min and with
degenerate helium and carbon-oxygen donors. This is one order of magnitude more
than the observed number of (probably) three. Conclusions. This overprediction
of short-period UCXBs implies that fewer systems are formed, or that a
super-Eddington mass transfer rate is more difficult to survive than assumed.
The very small number of observed long-period UCXBs with respect to
short-period UCXBs, the surprisingly high luminosity of the observed UCXBs with
orbital periods around 50 min, and the properties of the PSR J1719-1438 system
all point to much faster UCXB evolution than expected from angular momentum
loss via gravitational wave radiation alone. Old UCXBs, if they still exist,
probably have orbital periods longer than 2 h and have become very faint due to
either reduced accretion or quiescence, or have become detached. UCXBs are
promising candidate progenitors of isolated millisecond radio pulsars.


title:
Polarization dependences of terahertz radiation emitted by hot charge
  carriers in p-Te

abstract:
  Polarization dependences of the terahertz radiation emitted by hot charge
carriers in p-Te have been studied both theoretically and experimentally. The
angular dependences of the spontaneous radiation emission by hot carriers is
shown to originate from the anisotropy of their dispersion law and the
anisotropy of the dielectric permittivity of a tellurium crystal. We have shown
that the polarization dependences of radiation are determined by the angle
between the crystallographic axis C3 in p-Te and the polarization vector; they
are found to have a periodic character.


title:
Enhanced Proton Acceleration by an Ultrashort Laser Interaction with
  Structured Dynamic Plasma Targets

abstract:
  We experimentally demonstrate a notably enhanced acceleration of protons to
high energy by relatively modest ultrashort laser pulses and structured
dynamical plasma targets. Realized by special deposition of snow targets on
sapphire substrates and using carefully planned pre-pulses, high proton yield
emitted in a narrow solid angle with energy above 21MeV were detected from a
5TW laser. Our simulations predict that using the proposed scheme protons can
be accelerated to energies above 150MeV by 100TW laser systems.


title: Anisotropy in the cosmic radiation at TeV energy

abstract:
  In recent years very important results were obtained from cosmic ray
experiments about the arrival direction distribution of primaries in the TeV
energy range. As most of these particles are charged nuclei, they are deflected
by the magnetic field they pass through before reaching the Earth surface, the
effect of the Lorentz force being inversely proportional to the particle
energy. As far as the local interstellar medium is known, the gyroradius of a
10 TeV proton is expected to be only 100 a.u., small enough to make the arrival
direction distribution isotropic. Since 1930s a "large scale"
(90{\deg}-120{\deg}) anisotropy is known to exist, generally interpreted as the
combined effect of sources far away and magnetic fields nearby. Nonetheless, in
the last decade experiments like Tibet-ASg, Milagro, ARGO-YBJ and IceCube
discovered structures as wide as 10{\deg}-30{\deg} all over the sky at ~ 10 TeV
energy, what is unexplainable within the standard model of cosmic rays. In this
paper a review of the most recent experimental results about cosmic ray
anisotropy is given, together with the status of the art of theoretical efforts
aimed at interpreting them within the current cosmic-ray paradigma.


title: A Generalization of Fermat's Principle for Classical and Quantum Systems

abstract:
  The analogy between dynamics and optics had a great influence on the
development of the foundations of classical and quantum mechanics. We take this
analogy one step further and investigate the validity of Fermat's principle in
many-dimensional spaces describing dynamical systems (i.e., the quantum Hilbert
space and the classical phase and configuration space). We propose that if the
notion of a metric distance is well defined in that space and the velocity of
the representative point of the system is an invariant of motion, then a
generalized version of Fermat's principle will hold. We substantiate this
conjecture for time-independent quantum systems and for a classical system
consisting of coupled harmonic oscillators. An exception to this principle is
the configuration space of a charged particle in a constant magnetic field; in
this case the principle is valid in a frame rotating by half the Larmor
frequency, not the stationary lab frame.


title: Formation of Kinneyia via shear-induced instabilities in microbial mats

abstract:
  Kinneyia are a class of microbially mediated sedimentary fossils.
Characterised by clearly defined ripple structures, Kinneyia are generally
found in areas that were formally littoral habitats and covered by microbial
mats. To date there has been no conclusive explanation of the processes
involved in the formation of these fossils. Microbial mats behave like
viscoelastic fluids. We propose that the key mechanism involved in the
formation of Kinneyia is a Kelvin-Helmholtz type instability induced in a
viscoelastic film under flowing water. A ripple corrugation is spontaneously
induced in the film and grows in amplitude over time. Theoretical predictions
show that the ripple instability has a wavelength proportional to the thickness
of the film. Experiments carried out using viscoelastic films confirm this
prediction. The ripple pattern that forms has a wavelength roughly three times
the thickness of the film. This behaviour is independent of the viscosity of
the film and the flow conditions. Laboratory-analogue Kinneyia were formed via
the sedimentation of glass beads, which preferentially deposit in the troughs
of the ripples. Well-ordered patterns form, with both honeycomb-like and
parallel ridges being observed, depending on the flow speed. These patterns
correspond well with those found in Kinneyia, with similar morphologies,
wavelengths and amplitudes being observed.


title:
Theory of Interferometric Photon-Correlation Measurements:
  Differentiating Coherent from Chaotic Light

abstract:
  Interferometric photon-correlation measurements, which correspond to the
second-order intensity cross-correlations between the two output ports of an
unbalanced Michelson interferometer, are sensitive to both amplitude and phase
fluctuations of an incoming beam of light. Here, we present the theoretical
framework behind these measurements and show that they can be used to
unambiguously differentiate a coherent wave undergoing dynamical amplitude and
phase fluctuations from a chaotic state of light. This technique may thus be
used to characterize the output of nanolasers and monitor the onset of coherent
emission.


title: Non-separability does not relieve the problem of Bell's theorem

abstract:
  This paper addresses arguments that "separability" is an assumption of Bell's
theorem, and that abandoning this assumption in our interpretation of quantum
mechanics (a position sometimes referred to as "holism") will allow us to
restore a satisfying locality principle. Separability here means that all
events associated to the union of some set of disjoint regions are combinations
of events associated to each region taken separately.
  In this article, it is shown that: (a) localised events can be consistently
defined without implying separability; (b) the definition of Bell's locality
condition does not rely on separability in any way; (c) the proof of Bell's
theorem does not use separability as an assumption. If, inspired by
considerations of non-separability, the assumptions of Bell's theorem are
weakened, what remains no longer embodies the locality principle. Teller's
argument for "relational holism" and Howard's arguments concerning separability
are criticised in the light of these results. Howard's claim that Einstein
grounded his arguments on the incompleteness of QM with a separability
assumption is also challenged. Instead, Einstein is better interpreted as
referring merely to the existence of localised events. Finally, it is argued
that Bell rejected the idea that separability is an assumption of his theorem.


title:
On the stability of the boundary trace of the polynomial L^2-projection
  on triangles and tetrahedra (extended version)

abstract:
  For the reference triangle or tetrahedron $T$, we study the stability
properties of the $L^2(T)$-projection $\Pi_N$ onto the space of polynomials of
degree $N$. We show $\|\Pi_N u\|_{L^2(\partial T)}^2 \leq C \|u\|_{L^2(T)}
\|u\|_{H^1(T)}$. This implies optimal convergence rates for the approximation
error $\|u - \Pi_N u\|_{L^2(\partial T)}$ for all $u \in H^k(T)$, $k > 1/2$.


title:
Are Planetary Systems Filled to Capacity? A Study Based on Kepler
  Results

abstract:
  We used a sample of Kepler candidate planets with orbital periods less than
200 days and radii between 1.5 and 30 Earth radii to determine the typical
dynamical spacing of neighboring planets. To derive the intrinsic (i.e., free
of observational bias) dynamical spacing of neighboring planets, we generated
populations of planetary systems following various dynamical spacing
distributions, subjected them to synthetic observations by the Kepler
spacecraft, and compared the properties of observed planets in our simulations
with actual Kepler detections. We found that, on average, neighboring planets
are spaced 21.7 mutual Hill radii apart with a standard deviation of 9.5. This
dynamical spacing distribution is consistent with that of adjacent planets in
the Solar System. To test the packed planetary systems hypothesis, the idea
that all planetary systems are dynamically packed or filled to capacity, we
determined the fraction of systems that are dynamically packed by performing
long-term (10^8 years) numerical simulations. In each simulation, we integrated
a system with planets spaced according to our best-fit dynamical spacing
distribution but containing an additional planet on an intermediate orbit. The
fraction of simulations exhibiting signs of instability provides an approximate
lower bound on the fraction of systems that are dynamically packed; we found
that >31%, >35%, and >45% of 2-planet, 3-planet, and 4-planet systems are
dynamically packed, respectively. Such sizeable fractions suggest that many
planetary systems are indeed filled to capacity. This feature of planetary
systems is another profound constraint that formation and evolution models must
satisfy.


title:
The Rise and Fall of a Central Contributor: Dynamics of Social
  Organization and Performance in the Gentoo Community

abstract:
  Social organization and division of labor crucially influence the performance
of collaborative software engineering efforts. In this paper, we provide a
quantitative analysis of the relation between social organization and
performance in Gentoo, an Open Source community developing a Linux
distribution. We study the structure and dynamics of collaborations as recorded
in the project's bug tracking system over a period of ten years. We identify a
period of increasing centralization after which most interactions in the
community were mediated by a single central contributor. In this period of
maximum centralization, the central contributor unexpectedly left the project,
thus posing a significant challenge for the community. We quantify how the
rise, the activity as well as the subsequent sudden dropout of this central
contributor affected both the social organization and the bug handling
performance of the Gentoo community. We analyze social organization from the
perspective of network theory and augment our quantitative findings by
interviews with prominent members of the Gentoo community which shared their
personal insights.


title: Weak and strong no-arbitrage conditions for continuous financial markets

abstract:
  We propose a unified analysis of a whole spectrum of no-arbitrage conditions
for financial market models based on continuous semimartingales. In particular,
we focus on no-arbitrage conditions weaker than the classical notions of No
Arbitrage and No Free Lunch with Vanishing Risk. We provide a complete
characterisation of the considered no-arbitrage conditions, linking their
validity to the characteristics of the discounted asset price process and to
the existence and the properties of (weak) martingale deflators, and review
classical as well as recent results.


title:
Matrix-free GPU implementation of a preconditioned conjugate gradient
  solver for anisotropic elliptic PDEs

abstract:
  Many problems in geophysical and atmospheric modelling require the fast
solution of elliptic partial differential equations (PDEs) in "flat" three
dimensional geometries. In particular, an anisotropic elliptic PDE for the
pressure correction has to be solved at every time step in the dynamical core
of many numerical weather prediction models, and equations of a very similar
structure arise in global ocean models, subsurface flow simulations and gas and
oil reservoir modelling. The elliptic solve is often the bottleneck of the
forecast, and an algorithmically optimal method has to be used and implemented
efficiently. Graphics Processing Units have been shown to be highly efficient
for a wide range of applications in scientific computing, and recently
iterative solvers have been parallelised on these architectures. We describe
the GPU implementation and optimisation of a Preconditioned Conjugate Gradient
(PCG) algorithm for the solution of a three dimensional anisotropic elliptic
PDE for the pressure correction in NWP. Our implementation exploits the strong
vertical anisotropy of the elliptic operator in the construction of a suitable
preconditioner. As the algorithm is memory bound, performance can be improved
significantly by reducing the amount of global memory access. We achieve this
by using a matrix-free implementation which does not require explicit storage
of the matrix and instead recalculates the local stencil. Global memory access
can also be reduced by rewriting the algorithm using loop fusion and we show
that this further reduces the runtime on the GPU. We demonstrate the
performance of our matrix-free GPU code by comparing it to a sequential CPU
implementation and to a matrix-explicit GPU code which uses existing libraries.
The absolute performance of the algorithm for different problem sizes is
quantified in terms of floating point throughput and global memory bandwidth.


title:
Normalization of Polynomials in Algebraic Invariants of
  Three-Dimensional Orthogonal Geometry

abstract:
  In classical invariant theory, the Gr\"obner base of the ideal of syzygies
and the normal forms of polynomials of invariants are two core contents. To
improve the performance of invariant theory in symbolic computing of classical
geometry, advanced invariants are introduced via Clifford product. This paper
addresses and solves the two key problems in advanced invariant theory: the
Gr\"obner base of the ideal of syzygies among advanced invariants, and the
normal forms of polynomials of advanced invariants. These results beautifully
extend the straightening of Young tableaux to advanced invariants.


title:
Coalitional Game Theoretic Approach for Cooperative Transmission in
  Vehicular Networks

abstract:
  Cooperative transmission in vehicular networks is studied by using
coalitional game and pricing in this paper. There are several vehicles and
roadside units (RSUs) in the networks. Each vehicle has a desire to transmit
with a certain probability, which represents its data burtiness. The RSUs can
enhance the vehicles' transmissions by cooperatively relaying the vehicles'
data. We consider two kinds of cooperations: cooperation among the vehicles and
cooperation between the vehicle and RSU. First, vehicles cooperate to avoid
interfering transmissions by scheduling the transmissions of the vehicles in
each coalition. Second, a RSU can join some coalition to cooperate the
transmissions of the vehicles in that coalition. Moreover, due to the mobility
of the vehicles, we introduce the notion of encounter between the vehicle and
RSU to indicate the availability of the relay in space. To stimulate the RSU's
cooperative relaying for the vehicles, the pricing mechanism is applied. A
non-transferable utility (NTU) game is developed to analyze the behaviors of
the vehicles and RSUs. The stability of the formulated game is studied.
Finally, we present and discuss the numerical results for the 2-vehicle and
2-RSU scenario, and the numerical results verify the theoretical analysis.


title: Synthesis of New Layered Oxypnictides Sr2CrO2(FeAs)2

abstract:
  We successfully synthesized new layered iron oxypnictide Sr2CrO2(FeAs)2 by
solid-state-reaction techniques. This is the first report on the Fe-substituted
Sr2Mn3As2O2-type oxypnictides to our knowledge. A pellet of stoichiometric
mixtures of SrO, Cr and FeAs wrapped with tantalum foil was sintered at
900{\deg}C for 96 h. Results of x-ray diffraction measurement and Rietveld
refinements show that the structure of the sample belongs to the space group of
I4/mmm with the lattice constants of a = 3.9948(1) {\AA} and c = 18.447(1)
{\AA}. Temperature dependence of the resistivity for Sr2CrO2(FeAs)2 shows
semiconductor-like behavior. Additionally, the sample does not exhibit
superconducting transition in measurements of resistivity and magnetization
even in the low temperature down to 3 K.


title:
Yang-Lee zeros and the critical behavior of the infinite-range two- and
  three-state Potts models

abstract:
  The phase diagram of the two- and three-state Potts model with infinite-range
interactions, in the external field is analyzed by studying the partition
function zeros in the complex field plane. The tricritical point of the
three-state model is observed as the approach of the zeros to the real axis at
the nonzero field value. Different regimes, involving several first- and
second-order transitions of the complicated phase diagram of the three state
model are identified from the scaling properties of the zeros closest to the
real axis. The critical exponents related to the tricritical point and the
Yang-Lee edge singularity are well reproduced. Calculations are extended to the
negative fields, where the exact implicit expression for the transition line is
derived.


title: Difference Galois theory of linear differential equations

abstract:
  We develop a Galois theory for linear differential equations equipped with
the action of an endomorphism. This theory is aimed at studying the difference
algebraic relations among the solutions of a linear differential equation. The
Galois groups here are linear difference algebraic groups, i.e., matrix groups
defined by algebraic difference equations.


title:
A strong law of large numbers for branching processes: almost sure spine
  events

abstract:
  We demonstrate a novel strong law of large numbers for branching processes,
with a simple proof via measure-theoretic manipulations and spine theory.
Roughly speaking, any sequence of events that eventually occurs almost surely
for the spine entails the almost sure convergence of a certain sum over
particles in the population.


title:
The Born series for $S$-wave quartet $nd$ scattering at small cutoff
  values

abstract:
  Perturbative expansions, the Born series, of the scattering length and the
amplitude of $S$-wave neutron-deuteron scattering for spin quartet channel
below deuteron breakup threshold are studied in pionless effective field theory
at small cutoff values. A three-body contact interaction is introduced when the
integral equation is solved using the small cutoffs. After renormalizing the
three-body interaction by using the scattering length, we expand the integral
equation as the ordinary and inverted Born series. We find that the scattering
length and the phase shift are considerably well reproduced with a few terms of
the inverted Born series at relatively large cutoff values, $\Lambda\simeq 100$
MeV.


title:
Analytical treatment of long-term observations of the day-night
  asymmetry for solar neutrinos

abstract:
  The Earth's density distribution can be approximately considered piecewise
continuous at the scale of two-flavor oscillations of typical solar neutrinos,
such as the beryllium-7 and boron-8 neutrinos. This quite general assumption
appears to be enough to analytically calculate the day-night asymmetry factor
for such neutrinos. Using the explicit time averaging procedure, we show that,
within the leading-order approximation, this factor is determined by the
electron density within about one oscillation length under the detector,
namely, in the Earth's crust (and upper mantle for high-energy neutrinos). We
also evaluate the effect of the inner Earth's structure on the observed
asymmetry and show that it is suppressed and mainly comes from the neutrinos
observed near the winter and summer solstices. As a result, we arrive at the
strict interval constraint on the asymmetry, which is valid within quite a wide
class of Earth models.


title:
Phenomenology of QCD threshold resummation for gluino pair production at
  NNLL

abstract:
  We examine the impact of threshold resummation for the inclusive hadronic
production cross section of gluino pairs at next-to-next-to-leading-logarithmic
accuracy, compared to the exact next-to-leading-order cross section and the
next-to-next-to-leading-order approximation. Here, we apply formulas derived
recently in the classical Mellin-space formalism. Moreover, we give the
analytic input for the alternative momentum-space formalism and discuss the
crucial points of the numeric implementation. We find that soft resummation
keeps the hadronic cross section close to the fixed next-to-leading-order
result.


title: Accurate eigenvalue decomposition of arrowhead matrices and applications

abstract:
  We present a new algorithm for solving an eigenvalue problem for a real
symmetric arrowhead matrix. The algorithm computes all eigenvalues and all
components of the corresponding eigenvectors with high relative accuracy in
$O(n^{2})$ operations. The algorithm is based on a shift-and-invert approach.
Double precision is eventually needed to compute only one element of the
inverse of the shifted matrix. Each eigenvalue and the corresponding
eigenvector can be computed separately, which makes the algorithm adaptable for
parallel computing. Our results extend to Hermitian arrowhead matrices, real
symmetric diagonal-plus-rank-one matrices and singular value decomposition of
real triangular arrowhead matrices.


title: Polynomial over Associative D-Algebra

abstract:
  In the paper I considered algebra of polynomials over associative D-algebra
with unit. Using the tensor notation allows to simplify the representation of
polynomial. I considered questions related to divisibility of polynomial of any
power over polynomial of power 1.


title:
Competition/Enhancement of Two Probe Order Parameters in the Unbalanced
  Holographic Superconductor

abstract:
  We introduce and study a simple unbalanced holographic superconductor model
with two scalar order parameters. The attention is focused on the possibility
of coexisting orderings corresponding to the concomitant condensation of two
scalar operators. Through a probe analysis we show that an attractive or
repulsive direct interaction between the two bulk scalars leads respectively to
competition and enhancement of the associated condensates. The system at hand
is a toy model for studying generic multiple ordering in a strongly coupled
context and some comments are given about its applicability to the
ferromagnetic unconventional superconductors.


title:
Quantum Key Distribution With several intercept-resend attacks Via A
  Depolarizing Channel

abstract:
  The disturbance effect of a depolarizing channel on the security of the
quantum key distribution of the four state BB84 protocol with multiple
sequentiel intercept and resend attacks of many eavesdroppers, has been
studied. The quantum bit error rate and the mutual information are computed for
arbitray number of attacks.


title: G-convergence of linear differential equations

abstract:
  We discuss $G$-convergence of linear integro-differential-algebaric equations
in Hilbert spaces. We show under which assumptions it is generic for the limit
equation to exhibit memory effects. Moreover, we investigate which classes of
equations are closed under the process of $G$-convergence. The results have
applications to the theory of homogenization. As an example we treat Maxwell's
equation with the Drude-Born-Fedorov constitutive relation.


title: Sharper estimates for Chebyshev's functions $\vartheta$ and $\psi$

abstract:
  In this article we present some improved results for Chebyshev's functions
$\vartheta$ and $\psi$ using the new zero-free region obtained by H. Kadiri and
the calculated the first $10^{13}$ zeros of the Riemann zeta function on the
critical line by Xavier Gourdon. The methods in the proofs are similar to those
of Rosser-Shoenfeld papers on this subject.


title: Exponential Stability for Linear Evolutionary Equations

abstract:
  We give an approach to exponential stability within the framework of
evolutionary equations due to [R. Picard. A structural observation for linear
material laws in classical mathematical physics. Math. Methods Appl. Sci.,
32(14):1768-1803,2009]. We derive sufficient conditions for exponential
stability in terms of the material law operator, which is defined via an
analytic and bounded operator-valued function and give an estimate for the
expected decay rate. The results are illustrated by three examples:
differential-algebraic equations, partial differential equations with finite
delay and parabolic integro-differential equations.


title:
The production of K+K- pairs in proton-proton collisions below the phi
  meson threshold

abstract:
  The pp -> ppK+K- reaction was measured below the phi threshold at a beam
energy of 2.568 GeV using the COSY-ANKE magnetic spectrometer. By assuming that
the four-body phase space is distorted only by the product of two-body final
state interactions, fits to a variety of one-dimensional distributions permit
the evaluation of differential and total cross sections. The shapes of the
distributions in the Kp and Kpp invariant masses are reproduced only if the K-p
interaction is even stronger than that found at higher energy. The cusp effect
in the K+K- distribution at the K0K0bar threshold is much more clear and some
evidence is also found for coupling between the K-p and K0bar n channels.
However, the energy dependence of the total cross section cannot be reproduced
by considering only a simple product of such pair-wise final state
interactions.


title:
Speckle temporal stability in XAO coronagraphic images II. Refine model
  for quasi-static speckle temporal evolution for VLT/SPHERE

abstract:
  Observing sequences have shown that the major noise source limitation in
high-contrast imaging is due to the presence of quasi-static speckles. The
timescale on which quasi-static speckles evolve, is determined by various
factors, among others mechanical or thermal deformations. Understanding of
these time-variable instrumental speckles, and especially their interaction
with other aberrations, referred to as the pinning effect, is paramount for the
search of faint stellar companions. The temporal evolution of quasi-static
speckles is for instance required for a quantification of the gain expected
when using angular differential imaging (ADI), and to determine the interval on
which speckle nulling techniques must be carried out. Following an early
analysis of a time series of adaptively corrected, coronagraphic images
obtained in a laboratory condition with the High-Order Test bench (HOT) at ESO
Headquarters, we confirm our results with new measurements carried out with the
SPHERE instrument during its final test phase in Europe. The analysis of the
residual speckle pattern in both direct and differential coronagraphic images
enables the characterization of the temporal stability of quasi-static
speckles. Data were obtained in a thermally actively controlled environment
reproducing realistic conditions encountered at the telescope. The temporal
evolution of the quasi-static wavefront error exhibits linear power law, which
can be used to model quasi-static speckle evolution in the context of
forthcoming high-contrast imaging instruments, with implications for
instrumentation (design, observing strategies, data reduction). Such a model
can be used for instance to derive the timescale on which non-common path
aberrations must be sensed and corrected. We found in our data that
quasi-static wavefront error increases with ~0.7 angstrom per minute.


title:
DroidAnalytics: A Signature Based Analytic System to Collect, Extract,
  Analyze and Associate Android Malware

abstract:
  Smartphones and mobile devices are rapidly becoming indispensable devices for
many users. Unfortunately, they also become fertile grounds for hackers to
deploy malware and to spread virus. There is an urgent need to have a "security
analytic & forensic system" which can facilitate analysts to examine, dissect,
associate and correlate large number of mobile applications. An effective
analytic system needs to address the following questions: How to automatically
collect and manage a high volume of mobile malware? How to analyze a zero-day
suspicious application, and compare or associate it with existing malware
families in the database? How to perform information retrieval so to reveal
similar malicious logic with existing malware, and to quickly identify the new
malicious code segment? In this paper, we present the design and implementation
of DroidAnalytics, a signature based analytic system to automatically collect,
manage, analyze and extract android malware. The system facilitates analysts to
retrieve, associate and reveal malicious logics at the "opcode level". We
demonstrate the efficacy of DroidAnalytics using 150,368 Android applications,
and successfully determine 2,494 Android malware from 102 different families,
with 342 of them being zero-day malware samples from six different families. To
the best of our knowledge, this is the first reported case in showing such a
large Android malware analysis/detection. The evaluation shows the
DroidAnalytics is a valuable tool and is effective in analyzing malware
repackaging and mutations.


title:
Gromov width of non-regular coadjoint orbits of U(n), SO(2n) and
  SO(2n+1)

abstract:
  Let G be a compact connected Lie group G and T its maximal torus. The
coadjoint orbit O_lambda through lambda in Lie(T)^* is canonically a symplectic
manifold. Therefore we can ask the question about its Gromov width. In many
known cases the Gromov width is exactly the minimum over the set {<
alpha_j^{\vee},lambda > ; alpha_j^{\vee} a coroot and < alpha_j^{\vee},lambda >
positive}. We show that the Gromov width of coadjoint orbits of the unitary
group and of most of the coadjoint orbits of the special orthogonal group is at
least the above minimum. The proof uses the torus action coming from the
Gelfand-Tsetlin system.


title:
Sine-Gordon model coupled with a free scalar field emergent in the
  low-energy phase dynamics of a mixture of pseudospin-1/2 Bose gases with
  interspecies spin exchange

abstract:
  Using the approach of low-energy effective field theory, the phase diagram is
studied for a mixture of two species of pseudospin-$\1/2$ Bose atoms with
interspecies spin-exchange. There are four mean-field regimes on the parameter
plane of $g_e$ and $g_z$, where $g_e$ is the interspecies spin-exchange
interaction strength, while $g_z$ is the difference between the interaction
strength of interspecies scattering without spin-exchange of equal spins and
that of unequal spins. Two regimes, with $|g_z| > |g_e|$, correspond to ground
states with the total spins of the two species parallel or antiparallel along
$z$ direction, and the low energy excitations are equivalent to those of
two-component spinless Bosons. The other two regimes, with $|g_e| > |g_z|$,
correspond to ground states with the total spins of the two species parallel or
antiparallel on $xy$ plane, and the low energy excitations are described by a
sine-Gordon model coupled with a free scalar field, where the effective fields
are combinations of the phases of the original four Boson fields. In
(1+1)-dimension, they are described by Kosterlitz-Thouless renormalization
group (RG) equations, and there are three sectors in the phase plane of a
scaling dimension and a dimensionless parameter proportional to the strength of
the cosine interaction, both depending on the densities. The gaps of these
elementary excitations are experimental probes of the underlying many-body
ground states.


title: A tale of two Higgs

abstract:
  A new boson with mass ~125 GeV and properties similar to the Standard Model
Higgs has been discovered by both the ATLAS and CMS collaborations, with
significant observation in the ZZ* to 4 leptons and the diphoton channels. In
this work we ask whether the signals in these two channels can be due primarily
to two distinct resonances, each contributing dominantly to one channel. We
investigate this question in the framework of a 2HDM and several of its
extensions. We conservatively find that such a scenario is not possible in a
pure 2HDM, nor under the addition of vector-like quarks, but is allowed when
adding one or two top-like scalars, if one allows for sub-one tan\beta. The
resonances in the diboson and diphoton channels can then be two scalars, or a
scalar and a pseudoscalar, respectively. In each viable case, we further find
the expected future deviations in the diboson, diphoton, b \bar b and tau tau
rates, which will be useful in excluding the two-resonance scenario.


title:
The evolution of planetesimal swarms in self-gravitating protoplanetary
  discs

abstract:
  We investigate the kinematic evolution of planetesimals in self-gravitating
discs, combining Smoothed Particle Hydrodynamical (SPH) simulations of the disc
gas with a gravitationally coupled population of test particle planetesimals.
We find that at radii of 10s of au (which is where we expect planetesimals to
be possibly formed in such discs) the planetesimals' eccentricities are rapidly
pumped to values $>$ 0.1 within the timescales for which the disc is in the
self-gravitating regime. The high resulting velocity dispersion and the lack of
planetesimal concentration in the spiral arms means that the collision
timescale is very long and that the effect of those collisions that do occur is
destructive rather than leading to further planetesimal growth. We also use the
SPH simulations to calibrate Monte Carlo dynamical experiments: these can be
used to evolve the system over long timescales and can be compared with
analytical solutions of the diffusion equation in particle angular momentum
space. We find that if planetesimals are only formed in a belt at large radius
then there is significant scattering of objects to small radii; nevertheless
the majority of planetesimals remain at large radii. If planetesimals indeed
form at early evolutionary stages, when the disc is strongly self-gravitating,
then the results of this study constrain their spatial and kinematic
distribution at the end of the self-gravitating phase.


title:
Number and spin densities in the ground state of a trapped mixture of
  two pseudospin-1/2 Bose gases with interspecies spin-exchange interaction

abstract:
  We consider the ground state of a mixture of two pseudospin-$\1/2$ Bose gases
with interspecies spin exchange in a trapping potential. In the mean field
approach, the ground state can be described in terms of four wave functions
governed by a set of coupled Gross-Pitaevskii-like (GP-like) equations, which
differ from the usual GP equations in the existence of an interference term due
to spin-exchange coupling between the two species. Using these GP-like
equations, we calculate such ground state properties as chemical potentials,
density profiles and spin density profiles, which are directly observable in
experiments. We compare the cases with and without spin exchange. It is
demonstrated that the spin exchange between the two species lowers the chemical
potentials, tends to equalize the wave functions of the two pseudospin
components of each species, and thus homogenizes the spin density. The novel
features of the density and spin density profiles can serve as experimental
probes of this novel Bose system.


title: Testing the Pauli Exclusion Principle for Electrons

abstract:
  One of the fundamental rules of nature and a pillar in the foundation of
quantum theory and thus of modern physics is represented by the Pauli Exclusion
Principle. We know that this principle is extremely well fulfilled due to many
observations. Numerous experiments were performed to search for tiny violation
of this rule in various systems. The experiment VIP at the Gran Sasso
underground laboratory is searching for possible small violations of the Pauli
Exclusion Principle for electrons leading to forbidden X-ray transitions in
copper atoms. VIP is aiming at a test of the Pauli Exclusion Principle for
electrons with high accuracy, down to the level of 10$^{-29}$ - 10$^{-30}$,
thus improving the previous limit by 3-4 orders of magnitude. The experimental
method, results obtained so far and new developments within VIP2 (follow-up
experiment at Gran Sasso, in preparation) to further increase the precision by
2 orders of magnitude will be presented.


title:
Nonlocal porous medium equation: Barenblatt profiles and other weak
  solutions

abstract:
  A degenerate nonlinear nonlocal evolution equation is considered; it can be
understood as a porous medium equation whose pressure law is nonlinear and
nonlocal. We show the existence of sign changing weak solutions to the
corresponding Cauchy problem. Moreover, we construct explicit compactly
supported self-similar solutions which generalize Barenblatt profiles --- the
well-known solutions of the classical porous medium equation.


title:
A New Monte Carlo Based Algorithm for the Gaussian Process
  Classification Problem

abstract:
  Gaussian process is a very promising novel technology that has been applied
to both the regression problem and the classification problem. While for the
regression problem it yields simple exact solutions, this is not the case for
the classification problem, because we encounter intractable integrals. In this
paper we develop a new derivation that transforms the problem into that of
evaluating the ratio of multivariate Gaussian orthant integrals. Moreover, we
develop a new Monte Carlo procedure that evaluates these integrals. It is based
on some aspects of bootstrap sampling and acceptancerejection. The proposed
approach has beneficial properties compared to the existing Markov Chain Monte
Carlo approach, such as simplicity, reliability, and speed.


title: Control and ultrafast dynamics of a two-fluid polariton switch

abstract:
  We investigate the cross-interactions in a two-component polariton quantum
fluid coherently driven by two independent pumping lasers tuned at different
energies and momenta. We show that both the hysteresis cycles and the ON/OFF
threshold of one polariton signal can be entirely controlled by a second
polariton fluid. Furthermore, we study the ultrafast switching dynamics of a
driven polariton state, demonstrating the ability to control the polariton
population with an external laser pulse, in less than a few picoseconds.


title:
Homogenization of high-contrast and non symmetric conductivities for non
  periodic columnar structures

abstract:
  In this paper we determine, in dimension three, the effective conductivities
of non periodic high-contrast two-phase cylindrical composites, placed in a
constant magnetic field, without any assumption on the geometry of their cross
sections. Our method, in the spirit of the H-convergence of Murat-Tartar, is
based on a compactness result and the cylindrical nature of the microstructure.
The homogenized laws we obtain extend those of the periodic fibre-reinforcing
case of [M. Briane and L. Pater. Homogenization of high-contrast two-phase
conductivities perturbed by a magnetic field. Comparison between dimension two
and dimension three. J. Math. Anal. Appl., 393 (2) (2012), 563 -589] to the
case of periodic and non periodic composites with more general transversal
geometries.


title: Restriction Theorems for Principal Bundles and Some Consequences

abstract:
  The aim of this paper is to give a proof of the restriction theorems for
principal bundles with a reductive algebraic group as structure group in
arbitrary characteristic. Let $G$ be a reductive algebraic group over any field
$k=\bar{k}$, let $X$ be a smooth projective variety over $k$, let $H$ be a very
ample line bundle on $X$ and let $E$ be a semistable (resp. stable) principal
$G$-bundle on $X$ w.r.t. $H$. The main result of this paper is that the
restriction of $E$ to a general smooth curve which is a complete intersection
of ample hypersurfaces of sufficiently high degree's is again semistable (resp.
stable).


title:
Phase Stabilization of a Frequency Comb using Multipulse Quantum
  Interferometry

abstract:
  From the interaction between a frequency comb and an atomic qubit, we derive
quantum protocols for the determination of the carrier-envelope offset phase,
using the qubit coherence as a reference, and without the need of frequency
doubling or an octave spanning comb. Compared with a trivial interference
protocol, the multipulse protocol results in a polynomial enhancement of the
sensitivity O(N^{-2}) with the number N of laser pulses involved. We present
specializations of the protocols using optical or hyperfine qubits,
Lambda-schemes and Raman transitions, and introduce methods where the reference
is another phase-stable cw-laser or frequency comb.


title:
The high strain-rate behaviour of three molecular weights of
  polyethylene examined with a magnesium alloy split-Hopkinson pressure bar

abstract:
  A traditional split-Hopkinson pressure bar system has been modified by the
addition of ZK60A magnesium alloy pressure bars in order to increase the
resolution of data when examining specimens of low-density, high-density and
ultra-high molecular weight polyethylene. It was found that the low density of
the ZK60A allowed a decent increase in transmitted pulse amplitude, whilst its
relatively high yield strength afforded long-term reliability of the system.
The accuracy of data obtained from the fitted strain gauges was verified with
the use of a high-speed video camera, and was found to be an excellent match.


title:
Measurement of neutron yield by 62 MeV proton beam on a thick Beryllium
  target

abstract:
  The design of a low-power prototype of neutron amplifier recently proposed
within the INFN-E project indicated the need for more accurate called for
detailed data on the neutron yield produced by a proton beam with energy of
about 70 MeV impinging on a thick Beryllium target. Such measurement was
performed at the LNS superconducting cyclotron, covering a wide angular range
from 0 to 150 degrees and a complete neutron energy interval from thermal to
beam energy. Neutrons with energy above 0.5 MeV were measured by liquid
scintillators exploiting their Time of Flight to determine the kinetic energy.
For lower energy neutrons, down to thermal energy, a $^3$He detector was used.
The obtained data are in good agreement with previous measurements at 0 degree
with 66 MeV proton beam, covering neutron energies >10 MeV, as well as with
measurements at few selected angles with protons of 46, 55 and 113 MeV energy.
The present results extend the neutron yield data in the 60-70 MeV beam energy
range. A comparison of measured yields to MCNP and Geant4 Monte Carlo
simulations was performed.


title: Randomly trapped random walks

abstract:
  We introduce a general model of trapping for random walks on graphs. We give
the possible scaling limits of these Randomly Trapped Random Walks on $\mathbb
{Z}$. These scaling limits include the well-known fractional kinetics process,
the Fontes-Isopi-Newman singular diffusion as well as a new broad class we call
spatially subordinated Brownian motions. We give sufficient conditions for
convergence and illustrate these on two important examples.


title: Applications of a new separator theorem for string graphs

abstract:
  An intersection graph of curves in the plane is called a string graph.
Matousek almost completely settled a conjecture of the authors by showing that
every string graph of m edges admits a vertex separator of size O(\sqrt{m}\log
m). In the present note, this bound is combined with a result of the authors,
according to which every dense string graph contains a large complete balanced
bipartite graph. Three applications are given concerning string graphs G with n
vertices: (i) if K_t is not a subgraph of G for some t, then the chromatic
number of G is at most (\log n)^{O(\log t)}; (ii) if K_{t,t} is not a subgraph
of G, then G has at most t(\log t)^{O(1)}n edges,; and (iii) a lopsided
Ramsey-type result, which shows that the Erdos-Hajnal conjecture almost holds
for string graphs.


title: A p-adic Eisenstein measure for vector-weight automorphic forms

abstract:
  We construct a p-adic Eisenstein measure with values in the space of
vector-weight p-adic automorphic forms on certain unitary groups. This measure
allows us to p-adically interpolate special values of certain vector-weight
C-infinity automorphic forms, including Eisenstein series, as their weights
vary.
  We also explain how to extend our methods to the case of Siegel modular forms
and how to recover Nicholas Katz's p-adic families of Eisenstein series for
Hilbert modular forms.


title: Composite Boson Mapping for Lattice Boson Systems

abstract:
  We present a canonical mapping transforming physical boson operators into
quadratic products of cluster composite bosons that preserves matrix elements
of operators when a physical constraint is enforced. We map the 2D lattice
Bose-Hubbard Hamiltonian into $2\times 2$ composite bosons and solve it at mean
field. The resulting Mott insulator-superfluid phase diagram reproduces well
Quantum Monte Carlo results. The Higgs boson behavior along the particle-hole
symmetry line is unraveled and in remarkable agreement with experiment. Results
for the properties of the ground and excited states are competitive with other
state-of-the-art approaches, but at a fraction of their computational cost. The
composite boson mapping here introduced can be readily applied to frustrated
many-body systems where most methodologies face significant hurdles.


title: Thermally activated magnetization reversal in bulk BiFe0.5Mn0.5O3

abstract:
  We report on the synthesis and characterization of BiFe0.5Mn0.5O3, a
potential type-I multiferroic compound displaying temperature induced
magnetization reversal. Bulk samples were obtained by means of solid state
reaction carried out under the application of hydrostatic pressure at 6 GPa and
1100{\deg}C. The crystal structure is an highly distorted perovskite with no
cation order on the B site, where, besides a complex scheme of tilt and
rotations of the TM-O6 octahedra, large off-centering of the bismuth ions is
detected. Below T1 = 420 K the compound undergoes a first weak ferromagnetic
transition related to the ordering of iron rich clusters. At lower temperatures
(just below RT) two distinct thermally activated mechanisms are superimposed,
inducing at first an enhancement of the magnetization at T2 = 288 K, then a
spontaneous reversal process centered at T3 = 250 K, finally giving rise to a
negative response. The application of fields higher than 1500 Oe suppresses the
process, yielding a ferromagnetic like behaviour. The complementary use of
SQuID magnetometry and M\"ossbauer spectroscopy allowed the interpretation of
the overall magnetic behaviour in terms of an uncompensated weak competitive
coupling between non-equivalent clusters of interactions characterized by
different critical temperatures and resultant magnetizations. PACS numbers:
75.85.+t, 75.60.Jk, 76.80.+y, 75.30.Et, 75.30.Kz


title: Flavoured Naturalness

abstract:
  We show that a large mixing between the right-handed charm and top squarks
(i) is allowed by low-energy flavour constraints; (ii) reduces the experimental
bound on the stop mass; (iii) has a mild, but beneficial, effect on
fine-tuning; (iv) leads to interesting signatures at the LHC not presently
investigated by experiments. We estimate the current bound on the stop mass, in
presence of flavour mixing, and discuss the new collider signatures. The signal
in the t anti-c (c anti-t) + missing E_T channel is large enough that it can be
immediately searched for experimentally, while the signature with same-sign
tops and missing E_T requires a luminosity upgrade of the LHC.


title: Optical Conductivity of Twisted Bilayer Graphene

abstract:
  We calculate the finite-frequency conductivity of bilayer graphene with a
relative twist between the layers. The low frequency response at zero doping
shows a flat conductivity with value twice that of the monolayer case and at
higher frequency a strong absorption peak occurs. For finite doping, the low
frequency flat absorption is modified into a peak about zero frequency (the
Drude response) accompanied by an interband edge which results from the
transfer of spectral weight from interband to intraband absorption due to Pauli
blocking. If the system is doped sufficiently such that the chemical potential
reaches beyond the low-energy saddle point in the twisted bilayer band
structure, a strong low frequency absorption peak appears at an energy related
to an effective interlayer hopping energy, which may be used to identify this
parameter and confirm the existence of the saddle point which gives rise to a
low energy van Hove singularity in the electronic density of states.


title: Source integrals of asymptotic multipole moments

abstract:
  We derive source integrals for multipole moments that describe the behaviour
of static and axially symmetric spacetimes close to spatial infinity. We assume
isolated non-singular sources but will not restrict the matter content
otherwise. Some future applications of these source integrals of the asymptotic
multipole moments are outlined as well.


title:
Existence and Destruction of Kantorovich Main Continuous Solutions of
  Nonlinear Integral Equations

abstract:
  The sufficient conditions are obtained for existence of the main solution of
the nonlinear Volterra integral equation of the second kind on the semi-axis
and on a finite interval. The method for computation of this boundary interval
is designed. Beyond such integral the solution has the blow-up. The efficiency
of proposed technique is demonstrated on concrete examples.


title:
The spin-orbit interaction and the spin-spin interaction of photons in
  an inhomogeneous medium

abstract:
  By means of the optical metric, we investigate the propagation of a polarized
light in an inhomogeneous medium in this paper. We find that the evolution of
photons is affected by the spin-spin interaction of photons, besides the
spin-orbit interaction. Due to the spin-spin interaction, there is a small
deflection of the ray trajectory of the polarized light along the direction of
the inhomogeneity gradient of the medium. It is different from the transverse
deflection described by the spin Hall effect of photons.


title: Stability of Asymptotics of Christoffel-Darboux Kernels

abstract:
  We study the stability of convergence of the Christoffel-Darboux kernel,
associated with a compactly supported measure, to the sine kernel, under
perturbations of the Jacobi coefficients of the measure. We prove stability
under variations of the boundary conditions and stability in a weak sense under
$\ell^1$ and random $\ell^2$ diagonal perturbations. We also show that
convergence to the sine kernel at $x$ implies that $\mu(\{x\})=0$.


title:
On the Preference Relations with Negatively Transitive Asymmetric Part.
  I

abstract:
  Given a linearly ordered set I, every surjective map p: A --> I endows the
set A with a structure of set of preferences by "replacing" the elements of I
with their inverse images via p considered as "balloons" (sets endowed with an
equivalence relation), lifting the linear order on A, and "agglutinating" this
structure with the balloons. Every ballooning A of a structure of linearly
ordered set I is a set of preferences whose preference relation (not
necessarily complete) is negatively transitive and every such structure on a
given set A can be obtained by ballooning of certain structure of a linearly
ordered set I, intrinsically encoded in A. In other words, the difference
between linearity and negative transitivity is constituted of balloons. As a
consequence of this characterization, under certain natural topological
conditions on the set of preferences A furnished with its interval topology,
the existence of a continuous generalized utility function on A is proved.


title:
Effect of potential fluctuations on shot noise suppression in mesoscopic
  cavities

abstract:
  We perform a numerical investigation of the effect of the disorder associated
with randomly located impurities on shot noise in mesoscopic cavities. We show
that such a disorder becomes dominant in determining the noise behavior when
the amplitude of the potential fluctuations is comparable to the value of the
Fermi energy and for a large enough density of impurities. In contrast to
existing conjectures, random potential fluctuations are shown not to contribute
to achieving the chaotic regime whose signature is a Fano factor of 1/4, but,
rather, to the diffusive behavior typical of disordered conductors. In
particular, the 1/4 suppression factor expected for a symmetric cavity can be
achieved only in high-quality material, with a very low density of impurities.
As the disorder strength is increased, a relatively rapid transition of the
suppression factor from 1/4 to values typical of diffusive or quasi-diffusive
transport is observed. Finally, on the basis of a comparison between a
hard-wall and a realistic model of the cavity, we conclude that the specific
details of the confinement potential have a minor influence on noise.


title:
Bounds on the compactification scale of two universal extra dimensions
  from exclusive $b \to s \gamma$ decays

abstract:
  The exclusive radiative $B \to K^* \gamma$, $B \to K^*_2 \gamma$, $B_s \to
\phi \gamma$ and $\Lambda_b \to \Lambda \gamma$ decays are studied in a new
physics scenario with two universal extra dimensions compactified on a chiral
square. The computed branching fractions depend on the size $R$ of the extra
dimensions, and a comparison with the available measurements allows us to put
bounds on such a fundamental parameter. From the mode $B^0 \to K^{*0} \gamma$
we obtain the most stringent bound: $1 \over R>710$ GeV.


title:
Optical absorption in highly-strained Ge/SiGe quantum wells: the role of
  \Gamma-to-\Delta{} scattering

abstract:
  We report the observation of the quantum-confined Stark effect in Ge/SiGe
multiple quantum well heterostructures grown on Si(0.22)Ge(0.78) virtual
substrates. The large compressive strain in the Ge quantum well layers caused
by the lattice mismatch with the virtual substrate results in a blue shift of
the direct absorption edge, as well as a reduction in the \Gamma-valley
scattering lifetime because of strain-induced splittings of the conduction band
valleys. We investigate theoretically the \Gamma-valley carrier lifetimes by
evaluating the \Gamma-to-L and \Gamma-to-\Delta{} scattering rates in strained
Ge/SiGe semiconductor heterostructures. These scattering rates are used to
determine the lifetime broadening of excitonic peaks and the indirect
absorption in simulated absorption spectra, which are compared with measured
absorption spectra for quantum well structures with systematically-varied
dimensions. We find that \Gamma-to-\Delta{} scattering is significant in
compressively strained Ge quantum wells and that the \Gamma-valley electron
lifetime is less than 50 fs in the highly-strained structures reported here,
where \Gamma-to-\Delta{} scattering accounted for approximately half of the
total scattering rate.


title:
An R-matrix with pseudo-state (RMPS) approach to the single photon
  double ionization and excitation of the He-like Li$^{+}$ ion

abstract:
  The success of the R-matrix with pseudo-state (RMPS) method to model single
photoionization processes, benchmarked against dedicated synchrotron light
source measurements, is exploited and extended to investigate, single photon
double ionization cross-sections for the He-like, Li$^+$ ion. We investigate
these processes from both the ground state and the excited $\rm 1s2s^{1,3}S$
metastable levels of this He-like system. Comparisons of the results from the
R-matrix plus pseudo-state (RMPS) method are made with other state-of-the-art
theoretical approaches such as time-dependent close-coupling (TDCC), B-splines
and the convergent close-coupling (CCC). Excellent agreement with various other
theoretical approaches are achieved but differences occur which are
high-lighted and discussed. For the ground state the peak of the cross section
is $\sim$ 2 kilo-barns (Kb), that for the $\rm 1s2s^{1}S$ state is $\sim$ 6 Kb
and $\sim$ 1 Kb for the corresponding $\rm 1s2s^{3}S$ state. All the cross
sections for single photon double ionization are extremely small, being in the
region of 2Kb -- 10 Kb, or less, rendering their experimental determination
extremely challenging.


title:
On the problem of large-scale magnetic field generation in rotating
  compressible convection

abstract:
  Mean-field dynamo theory suggests that turbulent convection in a rotating
layer of electrically-conducting fluid produces a significant alpha-effect,
which is one of the key ingredients in any mean-field dynamo model. Provided
that this alpha-effect operates more efficiently than (turbulent) magnetic
diffusion, such a system should be capable of sustaining a large-scale dynamo.
However, in the Boussinesq model that was considered by Cattaneo&Hughes (2006)
the dynamo produced small-scale, intermittent magnetic fields with no
significant large-scale component. In this paper, we consider the compressible
analogue of the rotating convective layer that was considered by
Cattaneo&Hughes (2006). Varying the horizontal scale of the computational
domain, we investigate the dependence of the dynamo upon the rotation rate. Our
simulations indicate that these turbulent compressible flows can drive a
small-scale dynamo but, even when the layer is rotating very rapidly (with a
mid-layer Taylor number of Ta=10^8), we find no evidence for the generation of
a significant large-scale component of the magnetic field on a dynamical
timescale. Like Cattaneo&Hughes(2006), we measure a negligible (time-averaged)
alpha-effect when a uniform horizontal magnetic field is imposed across the
computational domain. Although the total horizontal magnetic flux is a
conserved quantity in these simulations, the (depth-dependent)
horizontally-averaged magnetic field always exhibits strong fluctuations. If
these fluctuations are artificially suppressed within the code, we measure a
significant mean electromotive force that is comparable to that found in
related calculations in which the alpha-effect is measured using the test-field
method, even though we observe no large-scale dynamo action.


title:
One-loop Kaehler potential in 5D gauged supergravity with generic
  prepotential

abstract:
  We calculate one-loop contributions to the Kaehler potential in 4D effective
theory of 5D gauged supergravity (SUGRA) on S^1/Z_2 with a generic form of the
prepotential and arbitrary boundary terms. Our result is applicable to a wide
class of 5D SUGRA models. The derivation is systematically performed by means
of an N=1 superfield formalism based on the superconformal formulation of 5D
SUGRA. As an illustrative example, we provide an explicit expression of the
Kaehler potential in the case of 5D flat spacetime.


title:
Prospects for high-resolution microwave spectroscopy of methanol in a
  Stark-deflected molecular beam

abstract:
  Recently, the extremely sensitive torsion-rotation transitions in methanol
have been used to set a tight constraint on a possible variation of the
proton-to-electron mass ratio over cosmological time scales. In order to
improve this constraint, laboratory data of increased accuracy will be
required. Here, we explore the possibility for performing high-resolution
spectroscopy on methanol in a Stark-deflected molecular beam. We have
calculated the Stark shift of the lower rotational levels in the ground
torsion-vibrational state of CH3OH and CD3OH molecules, and have used this to
simulate trajectories through a typical molecular beam resonance setup.
Furthermore, we have determined the efficiency of non-resonant multi-photon
ionization of methanol molecules using a femtosecond laser pulse. The described
setup is in principle suited to measure microwave transitions in CH3OH at an
accuracy below 10^{-8}.


title:
An analytic multi-currency model with stochastic volatility and
  stochastic interest rates

abstract:
  We introduce a tractable multi-currency model with stochastic volatility and
correlated stochastic interest rates that takes into account the smile in the
FX market and the evolution of yield curves. The pricing of vanilla options on
FX rates can be performed effciently through the FFT methodology thanks to the
affinity of the model Our framework is also able to describe many non trivial
links between FX rates and interest rates: a second calibration exercise
highlights the ability of the model to fit simultaneously FX implied
volatilities while being coherent with interest rate products.


title: Stopping strategies and gambler's ruin problem

abstract:
  We obtain absorption probabilities and expected time until absorption for
different stopping strategies in gambler's ruin problem using the concept of
multiple function barriers


title:
The Quasi-Maxwellian Equations of General Relativity: Applications to
  the Perturbation Theory

abstract:
  A comprehensive review of the equations of general relativity in the
quasi-Maxwellian (QM) formalism introduced by Jordan, Ehlers and Kundt is made.
Our main interest concerns its applications to the analysis of the perturbation
of standard cosmology in the Friedman-Lema\^itre-Robertson-Walker framework.
The major achievement of the QM scheme is its use of completely gauge
independent quantities. We shall see that in the QM-scheme we deal directly
with observable quantities. This reveals its advantage over the old method
introduced by Lifshitz et al that deals with perturbation in the standard
Einstein framework. For completeness, we compare the QM-scheme to the
gauge-independent method of Bardeen, a procedure consisting on particular
choices of the perturbed variables as a combination of gauge dependent
quantities.


title: The dynamics of semigroups of transcendental entire functions I

abstract:
  We consider the dynamics associated with an arbitrary semigroup of
transcendental entire functions. Fatou-Julia theory is used to investigate the
dynamics of these semigroups. Several results of the dynamics associated with
iteration of a transcendental entire function have been extended to
transcendental semigroup case. We also investigate the dynamics of conjugate
semigroups, Abelian transcendental semigroups and wandering and Baker domains
of transcendental semigroups.


title: Mechanically induced metal-insulator transition in carbyne

abstract:
  First-principles calculations for carbyne under strain predict that the
Peierls transition from symmetric cumulene to broken-symmetry polyyne structure
is enhanced as the material is stretched. Interpretation within a simple and
instructive analytical model suggests that this behavior is valid for arbitrary
1D metals. Further, numerical calculations of the anharmonic quantum
vibrational structure of carbyne show that zero-point atomic vibrations alone
eliminate the Peierls distortion in a mechanically free chain, preserving the
cumulene symmetry. The emergence and increase of Peierls dimerization under
tension then implies a qualitative transition between the two forms, which our
computations place around 3% strain. Thus, zero-point vibrations and mechanical
strain jointly produce a change in symmetry resulting in the transition from
metallic to insulating state. In any practical realization, it is important
that the effect is also chemically modulated by the choice of terminating
groups. Our findings are promising for applications such as electromechanical
switching and band gap tuning via strain, and besides carbyne itself, they
directly extend to numerous other systems that show Peierls distortion.


title: Modeling Stable Matching Problems with Answer Set Programming

abstract:
  The Stable Marriage Problem (SMP) is a well-known matching problem first
introduced and solved by Gale and Shapley (1962). Several variants and
extensions to this problem have since been investigated to cover a wider set of
applications. Each time a new variant is considered, however, a new algorithm
needs to be developed and implemented. As an alternative, in this paper we
propose an encoding of the SMP using Answer Set Programming (ASP). Our encoding
can easily be extended and adapted to the needs of specific applications. As an
illustration we show how stable matchings can be found when individuals may
designate unacceptable partners and ties between preferences are allowed.
Subsequently, we show how our ASP based encoding naturally allows us to select
specific stable matchings which are optimal according to a given criterion.
Each time, we can rely on generic and efficient off-the-shelf answer set
solvers to find (optimal) stable matchings.


title: Stability results for some fully nonlinear eigenvalue estimates

abstract:
  In this paper, we give some stability estimates for the Faber-Krahn
inequality relative to the eigenvalues of Hessian operators


title: Magnetic fields: Impact on the rotation curve of the Galaxy

abstract:
  We quantify the effects of magnetic fields, cosmic rays and gas pressure on
the rotational velocity of HI gas in the Milky Way, at galactic distances
between Rsun and 2Rsun. The magnetic field is modelled by two components; a
mainly azimuthal magnetic component and a small-scale tangled field. We
construct a range of plausible axisymmetric models consistent with the strength
of the total magnetic field as inferred from radio synchrotron data. In a
realistic Galactic disk, the pressure by turbulent motions, cosmic rays and the
tangled turbulent field provide radial support to the disk. Large-scale
(ordered) magnetic fields may or may not provide support to the disk, depending
on the local radial gradient of the azimuthal field. We show that for
observationally constrained models, magnetic forces cannot appreciably alter
the tangential velocity of HI gas within a galactic distance of 2Rsun.


title: Turbulent buoyant confined jet with variable source temperature

abstract:
  In this work, experimental and numerical investigations are considered for
confined buoyant turbulent jet with varying inlet temperatures. Results of the
experimental work and numerical simulations for the problem under consideration
are presented. Four cases of different variable inlet temperatures and
different flow rates are considered. The realizable k-epsilon turbulence model
is used to model the turbulent flow. Comparisons show good agreements between
simulated and measured results. The results indicate that temperatures along
the vertical axis vary, generally, in nonlinear fashion as opposed to the
approximately linear variation that was observed for the constant inlet
temperature that was done in a previous work. Furthermore, thermal
stratification exits particularly closer to the entrance region. Further away
from the entrance region the variation in temperatures becomes relatively
smaller. The stratification is observed since the start of the experiment and
continues during whole time. Numerical experiments for constant, monotone
increasing and monotone decreasing of inlet temperature are done to show its
effect on the buoyancy force in terms of Richardson number


title:
Determining the neutron star surface magnetic field strength of two Z
  sources

abstract:
  From the extreme position of disk motion, we infer the neutron star (NS)
surface magnetic field strength B_0 of Z-source GX 17+2 and Cyg X-2. The
inferred B_0 of GX 17+2 and Cyg X-2 are ~(1-5)X10^8 G and ~(1--3)X10^8 G},
respectively, which are not inferior to that of millisecond X-ray pulsars or
atoll sources. It is likely that the NS magnetic axis of Z sources is parallel
to the axis of rotation, which could result in the lack of pulsations in these
sources.


title: Continuous-Time Quantum Algorithms for Unstructured Problems

abstract:
  We consider a family of unstructured problems, for which we propose a method
for constructing analog, continuous-time quantum algorithms that are more
efficient than their classical counterparts. In this family of problems, which
we refer to as `scrambled output' problems, one has to find a minimum-cost
configuration of a given integer-valued n-bit function whose output values have
been scrambled in some arbitrary way. Special cases within this set of problems
are Grover's search problem of finding a marked item in an unstructured
database, certain random energy models, and the functions of the Deutsch-Josza
problem. We consider a couple of examples in detail. In the first, we provide a
deterministic analog quantum algorithm to solve the seminal problem of Deutsch
and Josza, in which one has to determine whether an n-bit boolean function is
constant (gives 0 on all inputs or 1 on all inputs) or balanced (returns 0 on
half the input states and 1 on the other half). We also study one variant of
the random energy model, and show that, as one might expect, its minimum energy
configuration can be found quadratically faster with a quantum adiabatic
algorithm than with classical algorithms.


title:
Optical-to-Near-Infrared Simultaneous Observations for the Hot Uranus
  GJ3470b: A Hint for Cloud-free Atmosphere

abstract:
  We present optical (g', R_c, and I_c) to near-infrared (J) simultaneous
photometric observations for a primary transit of GJ3470b, a Uranus-mass
transiting planet around a nearby M dwarf, by using the 50-cm MITSuME telescope
and the 188-cm telescope, both at Okayama Astrophysical Observatory. From these
data, we derive the planetary mass, radius, and density as 14.1 \pm 1.3
M_earth, 4.32^{+0.21}_{-0.10} R_earth, and 0.94 \pm 0.12 g cm^{-3},
respectively, thus confirming the low density that was reported by Demory et
al. based on the Spitzer/IRAC 4.5-micron photometry (0.72^{+0.13}_{-0.12} g
cm^{-3}). Although the planetary radius is about 10% smaller than that reported
by Demory et al., this difference does not alter their conclusion that the
planet possesses a hydrogen-rich envelope whose mass is approximately 10% of
the planetary total mass. On the other hand, we find that the planet-to-star
radius ratio (R_p/R_s) in the J band (0.07577^{+0.00072}_{-0.00075}) is smaller
than that in the I_c (0.0802 \pm 0.0013) and 4.5-micron
(0.07806^{+0.00052}_{-0.00054}) bands by 5.9% \pm 2.0% and 3.0% \pm 1.2%,
respectively. A plausible explanation for the differences is that the planetary
atmospheric opacity varies with wavelength due to absorption and/or scattering
by atmospheric molecules. Although the significance of the observed R_p/R_s
variations is low, if confirmed, this fact would suggest that GJ3470b does not
have a thick cloud layer in the atmosphere. This property would offer a wealth
of opportunity for future transmission-spectroscopic observations of this
planet to search for certain molecular features, such as H2O, CH4, and CO,
without being prevented by clouds.


title:
Fermi surface reconstruction of superoxygenated La$_2$CuO$_{4}$ with
  ordered oxygen interstitials

abstract:
  Novel imaging methods show that the mobile dopants in optimum doped
La$_2$CuO$_{4+y}$ (LCO) get self-organized, instead of randomly distributed.
Rigid-band models fail because of ordering of dopants and supercell
calculations are required to obtain the Fermi surface reconstruction. We have
performed advanced band calculations for a large supercell
La$_{16}$Cu$_8$O$_{32+N}$ where $N$=1 or 2 oxygen interstitials form rows in
the spacer La$_{16}$O$_{16+N}$ layers intercalated between the CuO$_2$ layers
as determined by scanning nano x-ray diffraction. The additional oc cupied
states made by interstitial oxygen orbitals sit well below the Fermi level
($E_F$) and lead to hole doping as expect ed. The unexpected results show that
in the heavily doped puddles the altered Cu(3d)-O(2p) band hybridization at
$E_F$ indu ces a multiband electronic structure with the formation of multiple
Fermi surface spots: a) small gaps appear in the folde d Fermi surface, b)
three mini-bands cross $E_F$ with reduced Fermi energies of 60, 150, and 240
meV respectively, c) the d ensity-of-states and band mass at $E_F$ show
substantial increases, and d) spin-polarized calculations show a moderate incr
ease of antiferromagnetic spin fluctuations. All calculated features are
favorable to enhance superconductivity however the comparison with experimental
methods probing the average electronic structure of cuprates will require the
description of the electronics of a network of multigap superconducting
puddles.


title: Immune networks: multi-tasking capabilities at medium load

abstract:
  Associative network models featuring multi-tasking properties have been
introduced recently and studied in the low load regime, where the number $P$ of
simultaneously retrievable patterns scales with the number $N$ of nodes as
$P\sim \log N$. In addition to their relevance in artificial intelligence,
these models are increasingly important in immunology, where stored patterns
represent strategies to fight pathogens and nodes represent lymphocyte clones.
They allow us to understand the crucial ability of the immune system to respond
simultaneously to multiple distinct antigen invasions. Here we develop further
the statistical mechanical analysis of such systems, by studying the medium
load regime, $P \sim N^{\delta}$ with $\delta \in (0,1]$. We derive three main
results. First, we reveal the nontrivial architecture of these networks: they
exhibit a high degree of modularity and clustering, which is linked to their
retrieval abilities. Second, by solving the model we demonstrate for $\delta<1$
the existence of large regions in the phase diagram where the network can
retrieve all stored patterns simultaneously. Finally, in the high load regime
$\delta=1$ we find that the system behaves as a spin glass, suggesting that
finite-connectivity frameworks are required to achieve effective retrieval.


title: Enhanced lepton flavour violation in the supersymmetric inverse seesaw

abstract:
  In minimal supersymmetric seesaw models, the contribution to lepton flavour
violation from Z-penguins is usually negligible. In this study, we consider the
supersymmetric inverse seesaw and show that, in this case, the Z-penguin
contribution dominates in several lepton flavour violating observables due to
the low scale of the inverse seesaw mechanism. Among the observables
considered, we find that the most constraining one is the muon to electron
conversion rate which is already restricting the otherwise allowed parameter
space of the model. Moreover, in this framework, the Z-penguins exhibit a
non-decoupling behaviour, which has previously been noticed in lepton flavour
violating Higgs decays.


title:
On the structure of phase transition maps for three or more coexisting
  phases

abstract:
  This paper is partly based on a lecture delivered by the author at the ERC
workshop "Geometric Partial Differential Equations" held in Pisa in September
2012. What is presented here is an expanded version of that lecture.


title: Towards a provably resilient scheme for graph-based watermarking

abstract:
  Digital watermarks have been considered a promising way to fight software
piracy. Graph-based watermarking schemes encode authorship/ownership data as
control-flow graph of dummy code. In 2012, Chroni and Nikolopoulos developed an
ingenious such scheme which was claimed to withstand attacks in the form of a
single edge removal. We extend the work of those authors in various aspects.
First, we give a formal characterization of the class of graphs generated by
their encoding function. Then, we formulate a linear-time algorithm which
recovers from ill-intentioned removals of $k \leq 2$ edges, therefore proving
their claim. Furthermore, we provide a simpler decoding function and an
algorithm to restore watermarks with an arbitrary number of missing edges
whenever at all possible. By disclosing and improving upon the resilience of
Chroni and Nikolopoulos's watermark, our results reinforce the interest in
regarding it as a possible solution to numerous applications.


title:
Online Similarity Prediction of Networked Data from Known and Unknown
  Graphs

abstract:
  We consider online similarity prediction problems over networked data. We
begin by relating this task to the more standard class prediction problem,
showing that, given an arbitrary algorithm for class prediction, we can
construct an algorithm for similarity prediction with "nearly" the same mistake
bound, and vice versa. After noticing that this general construction is
computationally infeasible, we target our study to {\em feasible} similarity
prediction algorithms on networked data. We initially assume that the network
structure is {\em known} to the learner. Here we observe that Matrix Winnow
\cite{w07} has a near-optimal mistake guarantee, at the price of cubic
prediction time per round. This motivates our effort for an efficient
implementation of a Perceptron algorithm with a weaker mistake guarantee but
with only poly-logarithmic prediction time. Our focus then turns to the
challenging case of networks whose structure is initially {\em unknown} to the
learner. In this novel setting, where the network structure is only
incrementally revealed, we obtain a mistake-bounded algorithm with a quadratic
prediction time per round.


title:
A Practical Cooperative Multicell MIMO-OFDMA Network Based on Rank
  Coordination

abstract:
  An important challenge of wireless networks is to boost the cell edge
performance and enable multi-stream transmissions to cell edge users.
Interference mitigation techniques relying on multiple antennas and
coordination among cells are nowadays heavily studied in the literature.
Typical strategies in OFDMA networks include coordinated scheduling,
beamforming and power control. In this paper, we propose a novel and practical
type of coordination for OFDMA downlink networks relying on multiple antennas
at the transmitter and the receiver. The transmission ranks, i.e.\ the number
of transmitted streams, and the user scheduling in all cells are jointly
optimized in order to maximize a network utility function accounting for
fairness among users. A distributed coordinated scheduler motivated by an
interference pricing mechanism and relying on a master-slave architecture is
introduced. The proposed scheme is operated based on the user report of a
recommended rank for the interfering cells accounting for the receiver
interference suppression capability. It incurs a very low feedback and backhaul
overhead and enables efficient link adaptation. It is moreover robust to
channel measurement errors and applicable to both open-loop and closed-loop
MIMO operations. A 20% cell edge performance gain over uncoordinated LTE-A
system is shown through system level simulations.


title:
An Inverse problem for the Magnetic Schr\"odinger Operator on a Half
  Space with partial data

abstract:
  In this paper we prove uniqueness for an inverse boundary value problem for
the magnetic Schr\"odinger equation in a half space, with partial data. We
prove that the curl of the magnetic potential $A$, when $A\in
W_{comp}^{1,\infty}(\ov{\R^3_{-}},\R^3)$, and the electric pontetial $q \in
L_{comp}^{\infty}(\ov{\R^3_{-}},\C)$ are uniquely determined by the knowledge
of the Dirichlet-to-Neumann map on parts of the boundary of the half space.


title:
Coherence creation in an optically thick medium by matched propagation
  of a chirped laser pulse pair

abstract:
  We consider the simultaneous propagation of a pair of Raman-resonant,
frequency-modulated (chirped) laser pulses in an optically thick medium,
modeled by an ensemble of $\Lambda$-atoms. A self-organization ('matching`)
effect is shown for the chirped pulse pair, which leads to a quasi-lossless
propagation. Furthermore, we demonstrate that a well-defined coherent
superposition of the atomic ground states and, correspondingly, a coherence is
robustly created in the medium that can be controlled by amplitudes of the
laser pulses. The proposed scheme can be applied to substantially increase the
efficiency of the optical wave mixing processes, as well as in other nonlinear
processes where the initial preparation of a spatially extended medium in a
coherent superposition state is required.


title: Rank change in Poisson dynamical systems

abstract:
  It is shown in this paper how a connection may be made between the symmetry
generators of the Hamiltonian (or potential) invariant under a symmetry group
$G$, and the subcasimirs that come about when the rank of the Poisson structure
of a dynamical system drops by an even integer. This {\em kinematics-dynamics}
connection is made by using the algebraic geometry of the orbit space in the
vicinity of rank change, and the extra null eigenvectors of the mass matrix
(Hessian with respect to symmetry generators) of the Hamiltonian (or
potential). Some physical interpretations of this point of view include a
control-theoretic prescription to study stability on various symplectic leaves
of the Poisson structure. Methods of Invariant Theory are utilized to provide
parametrization for the leaves of a Poisson dynamical system for the case where
a compact Lie group acts properly on the phase space, which is assumed to be
modeled by Poisson geometry.


title: Sedimentation and polar order of active bottom-heavy particles

abstract:
  Self-propelled particles in an external gravitational field have been shown
to display both an increased sedimentation length and polar order even without
particle interactions. Here, we investigate self-propelled particles which
additionally are bottom-heavy, that is they feel a torque aligning them to swim
against the gravitational field. For bottom-heavy particles the gravitational
field has the two opposite effects of i) sedimentation and ii) upward alignment
of the particles' swimming direction. We perform a multipole expansion of the
one-particle distribution with respect to orientation and derive expressions
for sedimentation length and mean particle orientation which we check against
Brownian Dynamics simulations. For large strength of gravity or small particle
speeds and aligning torque, we observe sedimentation with increased
sedimentation length compared with passive colloids but also active colloids
without bottom-heaviness. Increasing, for example, swimming speed the
sedimentation profile is inverted and the particles swim towards the top wall
of the enclosing box. We find maximal orientational order at intermediate
swimming speeds for both cases of particles with bottom-heaviness and those
without. Ordering unsurprisingly is increased for the bottom-heavy particles,
but this difference disappears at higher levels of activity and for very high
activities ordering goes to zero in both cases.


title: Conformal symmetry superalgebras

abstract:
  We show how the rigid conformal supersymmetries associated with a certain
class of pseudo-Riemannian spin manifolds define a Lie superalgebra. The even
part of this superalgebra contains conformal isometries and constant
R-symmetries. The odd part is generated by twistor spinors valued in a
particular R-symmetry representation. We prove that any manifold which admits a
conformal symmetry superalgebra of this type must generically have dimension
less than seven. Moreover, in dimensions three, four, five and six, we provide
the generic data from which the conformal symmetry superalgebra is prescribed.
For conformally flat metrics in these dimensions, and compact R-symmetry, we
identify each of the associated conformal symmetry superalgebras with one of
the conformal superalgebras classified by Nahm. We also describe several
examples for Lorentzian metrics that are not conformally flat.


title: A polynomial-time approximation scheme for Euclidean Steiner forest

abstract:
  We give a randomized O(n polylog n)-time approximation scheme for the Steiner
forest problem in the Euclidean plane. For every fixed eps > 0 and given n
terminals in the plane with connection requests between some pairs of
terminals, our scheme finds a (1 + eps)-approximation to the minimum-length
forest that connects every requested pair of terminals.


title: On the Orbits of the Magnetized Kepler Problems in Dimension 2k+1

abstract:
  It is demonstrated that, for the recently introduced classical magnetized
Kepler problems in dimension $2k+1$, the non-colliding orbits in the "external
configuration space" $\mathbb R^{2k+1}\setminus\{\mathbf 0\}$ are all conics,
moreover, a conic orbit is an ellipse, a parabola, and a branch of a hyperbola
according as the total energy is negative, zero, and positive. It is also
demonstrated that the Lie group ${\mr {SO}}^+(1,2k+1)\times {\bb R}_+$ acts
transitively on both the set of oriented elliptic orbits and the set of
oriented parabolic orbits.


title: Gauge-free Coleman-Weinberg Potential

abstract:
  The gauge-dependence of the one loop Coleman-Weinberg effective potential in
scalar electrodynamics is resolved using a gauge-free approach not requiring
any gauge-fixing of quantum fluctuations of the photon degrees of freedom. This
leads to a unique dynamical ratio at one loop of the Higgs mass to the photon
mass. We compare our approach and results with those obtained in geometric
framework of DeWitt and Vilkovisky, which maintains invariance under field
redefinitions as well as invariance under background gauge transformations, but
{\it requires}, in contrast to our approach, gauge fixing of {\it fluctuating}
photon fields. We also discuss possible modifications of the Coleman-Weinberg
potential if we adapt the DeWitt-Vilkovisky method to our gauge-free approach
for scalar QED.


title: Molecular content of polar-ring galaxies

abstract:
  We have searched for CO lines in a sample of 21 new morphologically
determined polar-ring galaxies (of which nine are kinematically confirmed),
obtained from a wide search in the Galaxy Zoo project by Moiseev and
collaborators. Polar-ring galaxies (PRG) are a unique class of objects, tracing
special episodes in the galaxy mass assembly: they can be formed through galaxy
interaction and merging, but also through accretion from cosmic filaments.
Furthermore, they enable the study of dark matter haloes in three dimensions.
The polar ring itself is a sub-system rich in gas, where molecular gas is
expected, and new stars are formed. Among the sample of 21 PRG, we have
detected five CO-rich systems, that can now be followed up with higher spatial
resolution. Their average molecular mass is 9.4 10**9 Mo, and their average gas
fraction is 27% of their baryonic mass, with a range from 15 to 43%, implying
that they just accreted a large amount of gas. The position of the detected
objects in the velocity-magnitude diagram is offset from the Tully-Fisher
relation of normal spirals, as was already found for PRGs. This work is part of
our multi-wavelength project to determine the detailed morphology and dynamics
of polar-ring galaxies, test through numerical models their formation scenario,
and deduce their dark matter content and 3D-shape.


title: A measure for the impact of research

abstract:
  The last few years have seen the proliferation of measures that quantify the
scientific output of researches. Yet, these measures focus on productivity,
thus fostering the "publish or perish" paradigm. This article proposes a
measure that aims at quantifying the impact of research de-emphasizing
productivity, thus providing scientists an alternative, conceivably fairer,
evaluation of their work. Emphasis is placed on the scientist rather than on
quantities that can grow unbounded. The measure, defined initially for
manuscripts, is then extended to researchers and institutions.


title: Ramond-Ramond corrections to type II supergravity at order $\alpha'^3$

abstract:
  Recently, it has been shown that the NS-NS corrections to the type II
supergravity given by Gross and Sloan are invariant under the linear T-duality.
In this paper, we study the invariance of this action under sequence of
S-duality and linear T-duality to find the R-R corrections to the supergravity
at order $\alpha'^3$, up to field redefinition.


title:
Role of genetic polymorphisms in transgenerational inheritance in
  budding yeast

abstract:
  Transgenerational inheritance of a trait is presumably affected by both
genetic and environmental factors but remains poorly understood. We studied the
effect of genetic polymorphisms on transgenerational inheritance of yeast
segregants that were derived from a cross between a laboratory strain and a
wild strain of Saccharomyces cerevisiae. For each SNP analyzed, the parental
allele present in less than half of the segregants panel was called the minor
allele (MA). We found a nonrandom distribution of MAs in the segregants,
indicating natural selection. We compared segregants with high MA content (MAC)
relative to those with less and found a more dramatic shortening of the lag
phase length for the high MAC group in response to 14 days of ethanol training.
Also, the short lag phase as acquired and epigenetically memorized by ethanol
training was more dramatically lost after 7 days of recovery in ethanol free
medium for the high MAC group. Sodium chloride treatment produced similar
observations. Using public datasets, we found MAC linkage to mRNA expression of
hundreds of genes. Finally, we found preferential effect of MAC on traits with
high number of known additive quantitative trait loci (QTLs). These results
provide evidence for the slightly deleterious nature of most MAs and a lower
capacity to maintain inheritance of traits in individuals or cells with greater
MAC, which have implications for disease prevention and treatment and the
"missing heritability" problem in complex traits and diseases.


title:
Synchronization and scaling properties of chaotic networks with multiple
  delays

abstract:
  We study chaotic systems with multiple time delays that range over several
orders of magnitude. We show that the spectrum of Lyapunov exponents (LE) in
such systems possesses a hierarchical structure, with different parts scaling
with the different delays. This leads to different types of chaos, depending on
the scaling of the maximal LE. Our results are relevant, in particular, for the
synchronization properties of hierarchical networks (networks of networks)
where the nodes of subnetworks are coupled with shorter delays and couplings
between different subnetworks are realized with longer delay times. Units
within a subnetwork can synchronize if the maximal exponent scales with the
shorter delay, long range synchronization between different subnetworks is only
possible if the maximal exponent scales with the long delay. The results are
illustrated analytically for Bernoulli maps and numerically for tent maps.


title:
Using cascading Bloom filters to improve the memory usage for de Brujin
  graphs

abstract:
  De Brujin graphs are widely used in bioinformatics for processing
next-generation sequencing data. Due to a very large size of NGS datasets, it
is essential to represent de Bruijn graphs compactly, and several approaches to
this problem have been proposed recently. In this work, we show how to reduce
the memory required by the algorithm of [3] that represents de Brujin graphs
using Bloom filters. Our method requires 30% to 40% less memory with respect to
the method of [3], with insignificant impact to construction time. At the same
time, our experiments showed a better query time compared to [3]. This is, to
our knowledge, the best practical representation for de Bruijn graphs.


title:
Can active-sterile neutrino oscillations lead to chaotic behavior of the
  cosmological lepton asymmetry?

abstract:
  While the cosmic baryon asymmetry has been measured at high accuracy to be
6.1*10^-10, a corresponding lepton asymmetry could be as large as 10^-2 if it
hides in the neutrino sector. It has been known for some time that a large
asymmetry can be generated from a small initial asymmetry given the existence
of a sterile neutrino with a mass less than the mass of the active neutrino.
While the magnitude of the final lepton asymmetry is deterministic, its sign
has been conjectured to be chaotic in nature. This has been proven in the
single momentum approximation, also known as the quantum rate equations, but
has up to now not been established using the full momentum dependent quantum
kinetic equations. Here we investigate this problem by solving the quantum
kinetic equations for a system of 1 active and 1 sterile neutrino on an
adaptive grid. We show that by increasing the resolution oscillations in the
lepton asymmetry are eliminated and that the sign of the lepton asymmetry is in
fact deterministic. This paper also serves as a launch paper for the adaptive
solver LASAGNA which is available at http://users-phys.au.dk/steen.


title: Bayesian Consensus Clustering

abstract:
  The task of clustering a set of objects based on multiple sources of data
arises in several modern applications. We propose an integrative statistical
model that permits a separate clustering of the objects for each data source.
These separate clusterings adhere loosely to an overall consensus clustering,
and hence they are not independent. We describe a computationally scalable
Bayesian framework for simultaneous estimation of both the consensus clustering
and the source-specific clusterings. We demonstrate that this flexible approach
is more robust than joint clustering of all data sources, and is more powerful
than clustering each data source separately. This work is motivated by the
integrated analysis of heterogeneous biomedical data, and we present an
application to subtype identification of breast cancer tumor samples using
publicly available data from The Cancer Genome Atlas. Software is available at
http://people.duke.edu/~el113/software.html.