title:
Extended hadron and two-hadron operators of definite momentum for
  spectrum calculations in lattice QCD

abstract:
  Multi-hadron operators are crucial for reliably extracting the masses of
excited states lying above multi-hadron thresholds in lattice QCD Monte Carlo
calculations. The construction of multi-hadron operators with significant
coupling to the lowest-lying multi-hadron states of interest involves combining
single hadron operators of various momenta. The design and implementation of
large sets of spatially-extended single-hadron operators of definite momentum
and their combinations into two-hadron operators are described. The single
hadron operators are all assemblages of gauge-covariantly-displaced, smeared
quark fields. Group-theoretical projections onto the irreducible
representations of the symmetry group of a cubic spatial lattice are used in
all isospin channels. Tests of these operators on 24^3 x 128 and 32^3 x 256
anisotropic lattices using a stochastic method of treating the low-lying modes
of quark propagation which exploits Laplacian Heaviside quark-field smearing
are presented. The method provides reliable estimates of all needed
correlations, even those that are particularly difficult to compute, such as
eta eta -> eta eta in the scalar channel, which involves the subtraction of a
large vacuum expectation value. A new glueball operator is introduced, and the
evaluation of the mixing of this glueball operator with a quark-antiquark
operator, pi-pi, and eta-eta operators is shown to be feasible.


title:
Modeling the interdependency of low-priority congestion control and
  active queue management

abstract:
  Recently, a negative interplay has been shown to arise when scheduling/AQM
techniques and low-priority congestion control protocols are used together:
namely, AQM resets the relative level of priority among congestion control
protocols. This work explores this issue by (i) studying a fluid model that
describes system dynamics of heterogeneous congestion control protocols
competing on a bottleneck link governed by AQM and (ii) proposing a system
level solution able to reinstate priorities among protocols.


title: Nucleon Structure using lattice QCD

abstract:
  A review of recent nucleon structure calculations within lattice QCD is
presented. The nucleon excited states, the axial charge, the isovector momentum
fraction and helicity distribution are discussed, assessing the methods applied
for their study, including approaches to evaluate the disconnected
contributions. Results on the spin carried by the quarks in the nucleon are
also presented.


title:
Status report on the analysis of inelastic neutron scattering from
  carbon, iron, yttrium and lead at 96 MeV

abstract:
  This work is part of an effort to provide more experimental data for the
(n,n'x) reaction. The experiments were carried out at The Svedberg Laboratory
in Uppsala, Sweden, at the quasi-mono-energetic neutron beam of 96 MeV, before
the facility was upgraded in 2004. Using an extended data analysis of data
primarily intended for measuring elastic neutron scattering only, it was found
to be possible to extract information on the inelastic scattering from several
nuclei. In the preliminary data analysis, an iterative forward-folding
technique was applied, in which a physically reasonable trial spectrum was
folded with the response function of the detector system and the output was
compared to the experimental data. As a result, double-differential cross
sections and angular distributions of inelastic neutron scattering from 12-C,
56-Fe, 89-Y and 208-Pb could be obtained. In this paper, a status update on the
efforts to improve the description of the detector response function is given.


title:
DeBruijn Strings, Double Helices, and the Ehrenfeucht-Mycielski
  Mechanism

abstract:
  We revisit the pseudo-random sequence introduced by Ehrenfeucht and Mycielski
and its connections with DeBruijn strings.


title:
Spontaneous symmetry breaking in 2D: Kibble-Zurek mechanism in
  temperature quenched colloidal monolayers

abstract:
  The Kibble-Zurek mechanism describes the formation of topological defects
during spontaneous symmetry breaking for quite different systems. Shortly after
the big bang, the isotropy of the Higgs-field is broken during the expansion
and cooling of the universe. Kibble proposed the formation of monopoles,
strings, and membranes in the Higgs field since the phase of the symmetry
broken field can not switch globally to gain the same value everywhere in
space. Zurek pointed out that the same mechanism is relevant for second order
phase transitions in condensed matter systems. Every finite cooling rate
induces the system to fall out of equilibrium which is due to the critical
slowing down of order parameter fluctuations: the correlation time diverges and
the symmetry of the system can not change globally but incorporates defects
between different domains. Depending on the cooling rate the heterogeneous
order parameter pattern are a fingerprint of critical fluctuations. In the
present manuscript we show that a monolayer of superparamagnetic colloidal
particles is ideally suited to investigate such phenomena. In thermal
equilibrium the system undergos continuous phase transitions according
KTHNY-theory. If cooled rapidly across the melting temperature the final state
is a polycrystal. We show, that the observations can not be explained with
nucleation of a supercooled fluid but is compatible with the Kibble-Zurek
mechanism.


title:
Strong Pauli-limiting behavior of $H_{c2}$ and uniaxial pressure
  dependencies in KFe2As2

abstract:
  KFe2As2 single crystals are studied using specific-heat, high-resolution
thermal-expansion, magnetization, and magnetostriction measurements. The
magnetization and magnetostriction data provide clear evidence for strong Pauli
limiting effects for magnetic fields parallel to the FeAs planes, suggesting
that KFe2As2 may be a good candidate to search for the
Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state. Using standard thermodynamic
relations, the uniaxial pressure derivatives of the critical temperature
($T_{c}$), the normal-state Sommerfeld coefficient ($\gamma_{n}$), the
normal-state susceptibility ($\chi$), and the thermodynamic critical field
($H_{c}$) are calculated from our data. We find that the close relationship
between doping and pressure as found in other Fe-based systems does not hold
for KFe2As2.


title: The Fisher-KPP equation with nonlinear fractional diffusion

abstract:
  We study the propagation properties of nonnegative and bounded solutions of
the class of reaction-diffusion equations with nonlinear fractional diffusion:
$u_{t} + (-\Delta)^s (u^m)=f(u)$. For all $0<s<1$ and $m> m_c=(N-2s)_+/N $, we
consider the solution of the initial-value problem with initial data having
fast decay at infinity and prove that its level sets propagate exponentially
fast in time, in contradiction to the traveling wave behaviour of the standard
KPP case, which corresponds to putting $s=1$, $m=1$ and $f(u)=u(1-u)$. The
proof of this fact uses as an essential ingredient the recently established
decay properties of the self-similar solutions of the purely diffusive
equation, $u_{t} + (-\Delta)^s u^m=0$.


title: Scalar Radiation in the Background of a Naked Singularity

abstract:
  We study scalar radiation spectra from a particle in circular orbit, in the
background of the Janis-Newman-Winicour (JNW) naked singularity. The
differences in the nature of the spectra, from what one obtains with a
Schwarzschild black hole, is established. We also compute the angular
distribution of the spectra.


title:
A direct method for the Boltzmann equation based on a pseudo-spectral
  velocity space discretization

abstract:
  A deterministic method is proposed for solving the Boltzmann equation. The
method employs a Galerkin discretization of the velocity space and adopts, as
trial and test functions, the collocation basis functions based on weights and
roots of a Gauss-Hermite quadrature. This is defined by means of half- and/or
full-range Hermite polynomials depending whether or not the distribution
function presents a discontinuity in the velocity space. The resulting
semi-discrete Boltzmann equation is in the form of a system of hyperbolic
partial differential equations whose solution can be obtained by standard
numerical approaches. The spectral rate of convergence of the results in the
velocity space is shown by solving the spatially uniform homogeneous relaxation
to equilibrium of Maxwell molecules. As an application, the two-dimensional
cavity flow of a gas composed by hard-sphere molecules is studied for different
Knudsen and Mach numbers. Although computationally demanding, the proposed
method turns out to be an effective tool for studying low-speed slightly
rarefied gas flows.


title: Metric stability of trees and tight spans

abstract:
  In this note, we prove optimal extension results for roughly isometric
relations between metric (R-)trees and injective metric spaces. This yields
sharp stability estimates, in terms of the Gromov-Hausdorff (GH) distance, for
certain metric spanning constructions: The GH distance of two metric trees
spanned by some subsets is smaller than or equal to the GH distance of these
sets. The GH distance of the injective hulls, or tight spans, of two metric
spaces is at most twice the GH distance between themselves.


title:
Periodic and Asymptotically Periodic Solutions of Systems of Nonlinear
  Difference Equations with Infinite Delay

abstract:
  In this work we study the existence of periodic and asymptotically periodic
solutions of a system of nonlinear Volterra difference equations with infinite
delay. By means of fixed point theory, we furnish conditions that guarantee the
existence of such periodic solutions.


title: Cosmological perturbations in $F(R)$ gravity

abstract:
  The quasi-static solutions of the matter density perturbation in $F(R)$
gravity models have been investigated in numerous papers. However, the
oscillating solutions in $F(R)$ gravity models have not been investigated
enough so far. In this paper, the oscillating solutions are also examined by
using appropriate approximations. And the behaviors of the matter density
perturbation in F(R) gravity models with singular evolutions of the physical
parameters are shortly investigated as applications of the approximated
calculations.


title:
Observables of a test-mass along an inclined orbit in a post-Newtonian
  approximated Kerr spacetime to leading-order-quadratic-in-spin

abstract:
  The orbital motion is derived for a non-spinning test-mass in the
relativistic, gravitational field of a rotationally deformed body not
restricted to the equatorial plane or spherical orbit. The gravitational field
of the central body is represented by the Kerr metric, expanded to second
post-Newtonian order including the linear and quadratic spin terms. The orbital
period, the intrinsic periastron advance, and the precession of the orbital
plane are derived with the aid of novel canonical variables and action-based
methods.


title:
Stochastic excitation during the decay of a two-level emitter subject to
  homodyne and heterodyne detection

abstract:
  We study the dynamics of an atomic two-level system decaying by spontaneous
emission of light. Subject to continuous detection of the radiated field, the
system tends with certainty to the ground state in the long time limit, but at
initial times the excited state population exhibits non-trivial stochastic
behavior. Employing methods from Ito calculus, we characterize this behavior,
and we show, for example, that the emitter, as a result of in-phase homodyne
measurements, may become fully excited during the decay process while
heterodyne and out of phase homodyne measurements do not drive the atom
completely into the excited state.


title: Qunatum Parrondo's games constructed by quantum random walk

abstract:
  We construct a Parrondo's game using discrete time quantum walks. Two lossing
games are represented by two different coin operators. By mixing the two coin
operators $U_{A}(\alpha_{A},\beta_{A},\gamma_{A})$ and
$U_{B}(\alpha_{B},\beta_{B},\gamma_{B})$, we may win the game. Here we mix the
two games in position instead of time. With a number of selections of the
parameters, we can win the game with sequences ABB, ABBB, \emph{et al}. If we
set $\beta_{A}=45^{\circ},\gamma_{A}=0,\alpha_{B}=0,\beta_{B}=88^{\circ}$, we
find the game 1\emph{}with {\normalsize
$U_{A}^{S}=U^{S}(-51^{\circ},45^{\circ},0)$,
$U_{B}^{S}=U^{S}(0,88^{\circ},-16^{\circ})$ will win and get the most
profit.}If we set
$\alpha_{A}=0,\beta_{A}=45^{\circ},\alpha_{B}=0,\beta_{B}=88^{\circ}$
and{\normalsize{} the game 2 with $U_{A}^{S}=U^{S}(0,45^{\circ},-51^{\circ})$,
$U_{B}^{S}=U^{S}(0,88^{\circ},-67^{\circ})$, will win most. And}game
1\emph{}{\normalsize is equivalent to the}game\emph{}2\emph{}with the changes
of sequences and steps. But at a large enough steps, the game will loss at
last.


title:
Stabilization of a fluid-solid system, by the deformation of the
  self-propelled solid. Part I: The linearized system

abstract:
  This paper is the first part of a work which consists in proving the
stabilization to zero of a fluid-solid system, in dimension 2 and 3. The
considered system couples a deformable solid and a viscous incompressible fluid
which satisfies the incompressible Navier-Stokes equations. By deforming
itself, the solid can interact with the environing fluid and then move itself.
The control function represents nothing else than the deformation of the solid
in its own frame of reference. We there prove that the velocities of the
linearized system are stabilizable to zero with an arbitrary exponential decay
rate, by a boundary deformation velocity which can be chosen in the form of a
feedback operator. We then show that this boundary feedback operator can be
obtained from an internal deformation of the solid which satisfies the
linearized physical constraints that a self-propelled solid has to satisfy.


title:
Short range magnetic order and effective suppression of
  superconductivity by manganese-doping in LaFe1-xMnxAsO1-yFy

abstract:
  We present a study of the structural and physical properties of directly hole
doped LaFe1-xMnxAsO (x = 0.0-0.2) and the influence of charge compensation /
electron-doping by additional F doping in LaFe0.9Mn0.1AsO1-yFy (y = 0.1-0.5).
High quality polycrystalline samples were prepared using a solid state
metathesis reaction. The unit cell increases upon Mn doping, but decreases
again when additional F is inserted. The semiconducting character of
LaFe1-xMnxAsO decreases with additional F doping. Muon spin relaxation (muSR)
measurements reveal short range magnetic order in LaFe1-xMnxAsO and a
suppression of magnetism by additional electron-doping with fluoride in
LaFe0.9Mn0.1AsO1-yFy. Superconductivity remains absent even though the
electronic preconditions are fulfilled in electron-doped LaFe0.9Mn0.1AsO1-yFy
at x > 0.1, which is suggestive of effective pair breaking by Mn in this
system.


title:
Stabilization of a fluid-solid system, by the deformation of the
  self-propelled solid. Part II: The nonlinear system

abstract:
  In this second part we prove that the full nonlinear fluid-solid system
introduced in Part I is stabilizable by deformations of the solid that have to
satisfy nonlinear constraints. Some of these constraints are physical and
guarantee the self-propelled nature of the solid. The proof is based on the
boundary feedback stabilization of the linearized system. From this boundary
feedback operator we construct a deformation of the solid which satisfies the
aforementioned constraints and which stabilizes the nonlinear system. The proof
is made by a fixed point method.


title: Pulse profiles from thermally emitting neutron stars

abstract:
  The problem of computing the pulse profiles from thermally emitting spots on
the surface of a neutron star in general relativity is reconsidered. We show
that it is possible to extend Beloborodov (2002) approach to include (multiple)
spots of finite size in different positions on the star surface. Results for
the pulse profiles are expressed by comparatively simple analytical formulas
which involve only elementary functions.


title:
Reliability test for the experimental results of electric quadrupole
  hyperfine structure constants and new assessment of nuclear quadrupole
  moments in $^{135,137}$Ba

abstract:
  We investigate electric quadrupole hyperfine structure constant ($B$) results
in $^{135}$Ba$^+$ and $^{137}$Ba$^+$ and compare their ratios with the reported
measurements of the ratio between the nuclear quadrupole moment ($Q$) values of
these isotopes. We carry out confidence tests for the reported experimental $B$
values and calculations of $B/Q$ from the present work. Inconsistencies in the
experimental $B$ values are observed in both the isotopes from different
experiments performed using the same techniques. The present calculations are
carried out using an all order relativistic many-body theory considering only
single and double excitations in the coupled-cluster ansatz. After a detailed
analysis of the results, the values of $Q$ we obtain for $^{135}$Ba and
$^{137}$Ba are 0.153(2)$b$ and 0.236(3)$b$, respectively, which differ by about
4% from the currently referred precise values.


title:
Deterministic and Stochastic Approaches to Supervisory Control Design
  for Networked Systems with Time-Varying Communication Delays

abstract:
  This paper proposes a supervisory control structure for networked systems
with time-varying delays. The control structure, in which a supervisor triggers
the most appropriate controller from a multi-controller unit, aims at improving
the closed-loop performance relative to what can be obtained using a single
robust controller. Our analysis considers average dwell-time switching and is
based on a novel multiple Lyapunov-Krasovskii functional. We develop stability
conditions that can be verified by semi-definite programming, and show that the
associated state feedback synthesis problem also can be solved using convex
optimization tools. Extensions of the analysis and synthesis procedures to the
case when the evolution of the delay mode is described by a Markov chain are
also developed. Simulations on small and large-scale networked control systems
are used to illustrate the effectiveness of our approach.


title:
Spectral line asymmetries in the metal-poor red giant HD 122563: CO5BOLD
  predictions versus observations

abstract:
  We study the influence of convection on the asymmetries and Doppler shifts of
Fe I spectral lines in the metal-poor red giant HD 122563. To this end, we
compute theoretical Fe I line shifts and line bisectors using 3D hydrodynamical
model atmosphere of HD 122563 calculated with the CO5BOLD code. We then make a
detailed comparison of the theoretical line shifts and bisectors with those
derived from the high quality HARPS spectrum of HD 122563 taken from the ESO
Science Archive Facility (R = 115 000, average signal-to-noise ratio, S/N =
310). In general, we find a good agreement between the theoretically predicted
and observed Doppler shifts of Fe I line cores, with somewhat larger
discrepancies seen in the case of weaker (equivalent width W < 5 pm) and
stronger lines (W > 11 pm). Both observed and theoretical coreshifts cover a
range between 0 and -1 km/s, with increasingly stronger blueshifts for weaker
lines and slight hints of a coreshift dependence on wavelength. Theoretical
bisectors reproduce the observed ones reasonably well too, however, theoretical
bisectors of the weak red (lambda > 600 nm) Fe I lines have blueshifts that are
by up to 200 m/s larger than observed. The obtained results therefore suggest
that the current CO5BOLD models are capable of reproducing the large-scale
velocity fields in the atmosphere of HD 122563 suficiently well. Nevertheless,
further efforts are needed in order to understand the physical reasons behind
the discrepancies in theoretical predictions and observed properties of the
weakest and strongest Fe I lines.


title: Forecasting Full-Path Network Congestion Using One Bit Signalling

abstract:
  In this paper, we propose a mechanism for packet marking called Probabilistic
Congestion Notification (PCN). This scheme makes use of the 1-bit Explicit
Congestion Notification (ECN) field in the Internet Protocol (IP) header. It
allows the source to estimate the exact level of congestion at each
intermediate queue. By knowing this, the source could take avoiding action
either by adapting its sending rate or by using alternate routes. The
estimation mechanism makes use of time series analysis both to improve the
quality of the congestion estimation and to predict, ahead of time, the
congestion level which subsequent packets will encounter.
  The proposed protocol is tested in ns-2 simulator using a background of real
Internet traffic traces. Results show that the methods can successfully
calculate the congestion at any queue along the path with low error levels.


title: A 26 ps RMS time-to-digital converter core for Spartan-6 FPGAs

abstract:
  We have designed, implemented and tested a time-to-digital converter core in
a low-cost Spartan-6 FPGA. Our design exploits the finite propagation speed in
carry chains to realize a delay line in which the propagation distance of the
incoming signal's edges is measured using hundreds of taps. This technique
enables the core to reach a precision far better than the minimum switching
period of the FPGA flip-flops. To compensate for process, voltage and
temperature (PVT) effects, our design uses a combination of two techniques:
startup calibration and online calibration. The startup calibration uses a
statistical method to estimate the delay between the taps of the delay line and
helps eliminate the effect of process variations. The online calibration, which
takes place without disruption of the core's operation, uses a ring oscillator
whose frequency instability is measured and used to compensate for subsequent
voltage and temperature effects on the delay line. Our tests show that our
design reaches a precision of 26 ps RMS over a temperature range of 37C to 48C.


title:
Criticisms of modelling packet traffic using long-range dependence
  (extended version)

abstract:
  This paper criticises the notion that long-range dependence is an important
contributor to the queuing behaviour of real Internet traffic. The idea is
questioned in two different ways. Firstly, a class of models used to simulate
Internet traffic is shown to have important theoretical flaws. It is shown that
this behaviour is inconsistent with the behaviour of real traffic traces.
Secondly, the notion that long-range correlations significantly affects the
queuing performance of traffic is investigated by destroying those correlations
in real traffic traces (by reordering). It is shown that the longer ranges of
correlations are not important except in one case with an extremely high load.


title:
Predictions of charged charmonium-like structures with hidden-charm and
  open-strange channels

abstract:
  We propose the initial single chiral particle emission mechanism, with which
the hidden-charm di-kaon decays of higher charmonia and charmonium-like states
are studied. Calculating the distributions of differential decay width, we
obtain the line shape of the $J/\psi K^+$ invariant mass spectrum of $\psi_i\to
J/\psi K^+K^-$, where $\psi_i=\psi(4415), Y(4660)$, and $\psi(4790)$. Our
numerical results show that there exist enhancement structures with both
hidden-charm and open-strange decays, which are near the
$D\bar{D}_s^*/D^*\bar{D}_s$ and $D^*\bar{D}_s^*/\bar{D}^*{D}_s^*$ thresholds.
These charged charmonium-like structures predicted in this Letter can be
accessible in future experiments, especially BESIII, BelleII, and SuperB.


title: The final log canonical model of $\bar{M}_6$

abstract:
  We describe the birational model of $\bar{M}_6$ given by quadric hyperplane
sections of the degree 5 del Pezzo surface. In the spirit of the genus 4 case
treated by Fedorchuk, we show that it is the last non-trivial space in the log
minimal model program for $\bar{M}_6$. We also obtain a new upper bound for the
moving slope of the moduli space.


title: Magnetic effects in curved quantum waveguides

abstract:
  The interplay among the spectrum, geometry and magnetic field in tubular
neighbourhoods of curves in Euclidean spaces is investigated in the limit when
the cross section shrinks to a point. Proving a norm resolvent convergence, we
derive effective, lower-dimensional models which depend on the intensity of the
magnetic field and curvatures. The results are used to establish complete
asymptotic expansions for eigenvalues. Spectral stability properties based on
Hardy-type inequalities induced by magnetic fields are also analysed.


title:
D6-Brane Model Building and Discrete Symmetries on T6/Z(2)xZ(6')xOR with
  Discrete Torsion

abstract:
  We review several geometric aspects and properties of the orbifold
T6/Z(2)xZ(6')xOR with discrete torsion, that are crucial with respect to global
model building and the search for discrete gauge symmetries in the context of
intersecting D6-brane models. A global six-stack Pati-Salam model is used for
illustration, and various characteristics of its effective field theory are
discussed.


title:
On entropy, regularity and rigidity for convex representations of
  hyperbolic manifolds

abstract:
  Given a convex representation $\rho:\Gamma\to\textrm{PGL}(d,\mathbb{R})$ of a
convex co-compact group $\Gamma$ of $\mathbb{H}^k$ we find upper bounds for the
quantity $\alpha h_\rho,$ where $h_\rho$ is the entropy of $\rho$ and $\alpha$
is the H\"older exponent of the equivariant map
$\partial\Gamma\to\mathbb{P}(\mathbb{R}^d).$ We also give rigidity statements
when the upper bound is attained. We then study Hitchin representations and
prove that if $\rho:\pi_1\Sigma\to\textrm{PSL}(d,\mathbb{R})$ is in the Hitchin
component then $\alpha h_\rho\leq 2/(d-1)$ (where $\alpha$ is the H\"older
exponent of the map $\zeta:\partial\mathbb{H}^2\to\mathscr{F}$) with equality
if and only if $\rho$ is Fuchsian.


title: Zeta Functions of F1-buildings

abstract:
  The analogue of the Bruhat-Tits building of a p-adic group in F1-geometry is
a single apartment. In this setting, the trace formula gives rise to a several
variable zeta function analogously to the p-adic case. The analogy carries on
to the fact that the restriction to certain lines yield zeta functions which
are defined in geometrical terms. Also, the classical formula of Ihara has an
analogue in this setting.


title: Geometric zeta functions for higher rank p-adic groups

abstract:
  The higher rank Lefschetz formula for p-adic groups is used to prove
rationality of a several-variable zeta function attached to the action of a
p-adic group on its Bruhat-Tits building. By specializing to certain lines one
gets one-variable zeta functions, which then can be related to geometrically
defined zeta functions


title: A Fast Improved Fat Tree Encoder for Wave Union TDC in an FPGA

abstract:
  Up to the present, the wave union method can achieve the best timing
performance in FPGA based TDC designs. However, it should be guaranteed in such
a structure that the non-thermometer code to binary code (NTH2B) encoding
process should be finished within just one system clock cycle. So the
implementation of the NTH2B encoder is quite challenging considering the high
speed requirement. Besides, the high resolution wave union TDC also demands the
encoder to convert an ultra-wide input code to a binary code. We present a fast
improved fat tree encoder (IFTE) to fulfill such requirements, in which bubble
error suppression is also integrated. With this encoder scheme, a wave union
TDC with 7.7 ps RMS and 3.8 ps effective bin size was implemented in an FPGA
from Xilinx Virtex 5 family. An encoding time of 8.33 ns was achieved for a
276-bit non-thermometer code to a 9-bit binary code conversion. We conducted a
series of tests on the oscillating period of the wave union launcher, as well
as the overall performance of the TDC; test results indicate that the IFTE
works well. In fact, in the implementation of this encoder, no manual routing
or special constrains were required; therefore, this IFTE structure could also
be further applied in other delay chain based FPGA TDCs.


title:
A fictitious domain approach for the Stokes problem based on the
  extended finite element method

abstract:
  In the present work, we propose to extend to the Stokes problem a fictitious
domain approach inspired by eXtended Finite Element Method and studied for
Poisson problem in [Renard]. The method allows computations in domains whose
boundaries do not match. A mixed finite element method is used for fluid flow.
The interface between the fluid and the structure is localized by a level-set
function. Dirichlet boundary conditions are taken into account using Lagrange
multiplier. A stabilization term is introduced to improve the approximation of
the normal trace of the Cauchy stress tensor at the interface and avoid the
inf-sup condition between the spaces for velocity and the Lagrange multiplier.
Convergence analysis is given and several numerical tests are performed to
illustrate the capabilities of the method.


title: Uncertainty Principle Respects Locality

abstract:
  The notion of nonlocality implicitly implies there might be some kind of
spooky action at a distance in nature, however, the validity of quantum
mechanics has been well tested up to now. In this work it is argued that the
notion of nonlocality is physically improper, the basic principle of locality
in nature is well respected by quantum mechanics, namely, the uncertainty
principle. We show that the quantum bound on the Clauser, Horne, Shimony, and
Holt (CHSH) inequality can be recovered from the uncertainty relation in a
multipartite setting. We further argue that the super-quantum correlation
demonstrated by the nonlocal box is not physically comparable with the quantum
one. The origin of the quantum structure of nature still remains to be
explained, some post-quantum theory which is more complete in some sense than
quantum mechanics is possible and might not necessarily be a hidden variable
theory.


title:
Dissipation enhancement from a single vortex reconnection in superfluid
  helium

abstract:
  We investigate a single vortex reconnection event in superfluid helium at
finite temperatures using the vortex filament model. The reconnection induces
Kelvin waves which strongly increase energy dissipation. We evaluate the mutual
friction dissipation from the reconnection and show that the dissipation power
has universal form, which is seen by scaling both time (measured from the
reconnection event) and power by the mutual friction parameter alpha. This
observation allows us to conclude that the Kelvin-wave cascade is not important
in the energy dissipation process within the range alpha > 0.001. Rather, the
energy is directly transferred from Kelvin waves to the normal component.
Moreover, while the excited Kelvin waves greatly enhance energy dissipation, no
similar change is seen in angular momentum from the reconnection event. This
result has similarities with recent 3He-B measurements. Our results also
confirm another earlier observation that the minimum distance between vortices
scales approximately as d ~ sqrt(|t-trec|), both before and after the
reconnection event.


title: Chern-Simons terms in Lifshitz like quantum electrodynamics

abstract:
  In this work the generation of generalized Chern-Simons terms in three
dimensional quantum electrodynamics with high spatial derivatives is studied.
We analyze the self-energy corrections to the gauge field propagator by
considering an expansion of the amplitude up to third order in the external
momenta. The divergences of the corrections are determined and explicit forms
for the Chern-Simons terms with high derivatives are obtained. Some unusual
aspects of the calculation are stressed and the existence of a smooth isotropic
limit is proved. The transversality of the anisotropic gauge propagator is also
discussed.


title: Two-dimensional gradient Ricci solitons revisited

abstract:
  In this note, we complete the classification of the geometry of non-compact
two-dimensional gradient Ricci solitons. As a consequence, we obtain two
corollaries: First, a complete two-dimensional gradient Ricci soliton has
bounded curvature. Second, we give examples of complete two-dimensional
expanding Ricci solitons with negative curvature that are topologically disks
and are not hyperbolic space.


title: Automorphisms of a non-type I C*-algebra

abstract:
  Glimm's theorem says that a UHF algebra is almost embedded in a separable
$C^*$-algebra not of type I. Applying his methods we obtain a covariant version
of his result; a UHF algebra with a product type automorphism is covariantly
embedded in such a $C^*$-algebra equipped with an automorphism with full Connes
spectrum.


title: From Fourier to Gegenbauer: Dimension walks on spheres

abstract:
  We show that the even- resp. odd-dimensional Schoenberg coefficients in
Gegenbauer expansions of isotropic positive definite functions on the d-sphere
can be expressed as linear combinations of Fourier resp. Legendre coefficients,
and we give closed form expressions for the coefficients involved in these
expansions.


title: A J^PG=1++ Charged Resonance in the Y(4260) to pi+pi- J/psi Decay?

abstract:
  New BES and Belle data show a peak in the Y(4260) decay into J/psi plus one
charged pion. We point out that the peak might correspond to a charged
resonance at about 3880 MeV predicted time ago within a tetraquark model. The
same tetraquark model predicts another peak at about 100 MeV below the observed
one. We discuss the possibility of having it in present data. On the other hand
we expect that if the molecular picture were the correct one, a peak
corresponding to a D* D*bar state should appear at about 4020 MeV.


title:
The (2+1)-d U(1) Quantum Link Model Masquerading as Deconfined
  Criticality

abstract:
  The $(2+1)$-d U(1) quantum link model is a gauge theory, amenable to quantum
simulation, with a spontaneously broken SO(2) symmetry emerging at a quantum
phase transition. Its low-energy physics is described by a $(2+1)$-d $\RP(1)$
effective field theory, perturbed by a dangerously irrelevant SO(2) breaking
operator, which prevents the interpretation of the emergent pseudo-Goldstone
boson as a dual photon. At the quantum phase transition, the model mimics some
features of deconfined quantum criticality, but remains linearly confining.
Deconfinement only sets in at high temperature.


title:
A practical system for improved efficiency in frequency division
  multiplexed wireless networks

abstract:
  Spectral efficiency is a key design issue for all wireless communication
systems. Orthogonal frequency division multiplexing (OFDM) is a very well-known
technique for efficient data transmission over many carriers overlapped in
frequency. Recently, several papers have appeared which describe spectrally
efficient variations of multi-carrier systems where the condition of
orthogonality is dropped. Proposed techniques suffer from two weaknesses:
Firstly, the complexity of generating the signal is increased. Secondly, the
signal detection is computationally demanding. Known methods suffer either
unusably high complexity or high error rates because of the inter-carrier
interference. This work addresses both problems by proposing new transmitter
and receiver arch itectures whose design is based on using the simplification
that a rational Spectrally Efficient Frequency Division Multiplexing (SEFDM)
system can be treated as a set of overlapped and interleaving OFDM systems.
  The efficacy of the proposed designs is shown through detailed simulation of
sys tems with different signal types and carrier dimensions. The decoder is
heuristic but in practice produces very good results which are close to the
theoretical best performance in a variety of settings. The system is able to
produce efficiency gains of up to 20% with negligible impact on the required
signal to noise ratio.


title:
Diamagnetism of YBa$_{2}$Cu$_{3}$O$_{6+x}$ crystals above $T_c$~:
  evidence for Gaussian fluctuations

abstract:
  The magnetization of three high-quality single crystals of
YBa$_{2}$Cu$_{3}$O$_{6+x}$, from slightly overdoped to heavily underdoped,has
been measured using torque magnetometry. Striking effects in the angular
dependence of the torque for the two underdoped crystals, a few degrees above
the superconducting transition temperature ($T_c$) are described well by the
theory of Gaussian superconducting fluctuations using a single adjustable
parameter. The data at higher temperatures ($T$) are consistent with a strong
cut-off in the fluctuations for $T\gtrsim1.1T_c$. Numerical estimates suggest
that inelastic scattering could be responsible for this cut-off.


title: Study of B0 -> D*- pi+ pi- pi+ and B0 -> D*- K+ pi- pi+ decays

abstract:
  Using proton-proton collision data collected by the LHCb experiment at
sqrt(s) = 7 TeV, corresponding to an integrated luminosity of 1.0 fb^{-1}, the
ratio of branching fractions of the B0 -> D*- pi+ pi- pi+ decay relative to the
B0 -> D*- pi+ decay is measured to be B(B0 -> D*- pi+ pi- pi+) / B(B0 -> D*-
pi+) = 2.64 \pm 0.04 (stat.) \pm 0.13 (syst.). The Cabibbo-suppressed decay B0
-> D*- K+ pi- pi+ is observed for the first time and the measured ratio of
branching fractions is B(B0 -> D*- K+ pi- pi+) / B(B0 -> D*- pi+ pi- pi+) =
(6.47 \pm 0.37 (stat.) \pm 0.35 (syst.)) x 10^{-2}. A search for orbital
excitations of charm mesons contributing to the B0 -> D*- pi+ pi- pi+ final
state is also performed, and the first observation of the B0 ->
Dbar_{1}(2420)^0 pi+ pi- decay is reported with the ratio of branching
fractions B(B0 -> (Dbar_{1}(2420)^0 -> D*- pi+) pi- pi+) / B(B0 -> D*- pi+ pi-
pi+) = (2.04 \pm 0.42 (stat.) \pm 0.22 (syst.)) x 10^{-2}, where the numerator
represents a product of the branching fractions B(B0 -> Dbar_{1}(2420)^0 pi-
pi+) and B(Dbar_{1}(2420)^0 -> D*- pi+).


title: Primal implication as encryption

abstract:
  We propose a "cryptographic" interpretation for the propositional connectives
of primal infon logic introduced by Y. Gurevich and I. Neeman and prove the
corresponding soundness and completeness results. Primal implication
$\imp{\varphi}{\psi}$ corresponds to the encryption of $\psi$ with a secret key
$\varphi$, primal disjunction $\vp{\varphi}{\psi}$ is a group key and $\bot$
reflects some backdoor constructions such as full superuser permissions or a
universal decryption key. For the logic of $\bot$ as a universal key (it was
never considered before) we prove that the derivability problem has linear time
complexity. We also show that the universal key can be emulated using primal
disjunction.


title: Geodesic motion in the (rotating) black string spacetime

abstract:
  In this article we study the geodesic motion of test particles and light in
the five-dimensional (rotating) black string spacetime. If a compact dimension
is added to the four-dimensional Schwarzschild or Kerr spacetime, the new
five-dimensional metric describes a (rotating) black string. The geodesics in
the Schwarzschild and Kerr spacetime have been studied in great detail,
however, when a compact dimension is added new behaviour occurs. We present the
analytical solutions of the geodesic equations and discuss the possible orbits.
The motion in the ordinary four-dimensional Schwarzschild and Kerr spacetime is
compared to the motion in the (rotating) black string spacetime.


title:
Resonant tunnelling and negative differential conductance in graphene
  transistors

abstract:
  The chemical stability of graphene and other free-standing two-dimensional
crystals means that they can be stacked in different combinations to produce a
new class of functional materials, designed for specific device applications.
Here we report resonant tunnelling of Dirac fermions through a boron nitride
barrier, a few atomic layers thick, sandwiched between two graphene electrodes.
The resonant peak in the device characteristics occurs when the electronic
spectra of the two electrodes are aligned. The resulting negative differential
conductance persists up to room temperature and is gate voltage-tuneable due to
graphene's unique Dirac-like spectrum. Whereas conventional resonant tunnelling
devices comprising a quantum well sandwiched between two tunnel barriers are
tens of nanometres thick, the tunnelling carriers in our devices cross only a
few atomic layers, offering the prospect of ultra-fast transit times. This
feature, combined with the multi-valued form of the device characteristics, has
potential for applications in high-frequency and logic devices.


title:
Renormalized perturbation theory and scaling for an impurity Anderson
  model

abstract:
  We demonstrate the effectiveness of a generalized renormalized perturbational
approach to calculate the induced magnetization for the single impurity
Anderson model with a strong on-site interaction, using flow equations for
renormalized parameters to scale from a weak correlation to a strong
correlation regime. We show that, using simple approximation schemes in
different parameter regimes, remarkably accurate results can be obtained for
all magnetic field values by comparing the results with those from direct
numerical renormalization group and Bethe ansatz calculations.


title:
The Multiphase Structure and Power Sources of Galactic Winds in Major
  Mergers

abstract:
  Massive, galaxy-scale outflows are known to be ubiquitous in major mergers of
disk galaxies in the local universe. In this paper, we explore the multiphase
structure and power sources of galactic winds in six ultraluminous infrared
galaxies (ULIRGs) at z < 0.06 using deep integral field spectroscopy with the
Gemini Multi-Object Spectrograph (GMOS) on Gemini North. We probe the neutral,
ionized, and dusty gas phases using Na I D, strong emission lines ([O I],
Halpha, and [N II]), and continuum colors, respectively. We separate outflow
motions from those due to rotation and tidal perturbations, and find that all
of the galaxies in our sample host high-velocity flows on kiloparsec scales.
The properties of these outflows are consistent with multiphase (ionized,
neutral, and dusty) collimated bipolar winds emerging along the minor axis of
the nuclear disk to scales of 1-2 kpc. In two cases, these collimated winds
take the form of bipolar superbubbles, identified by clear kinematic
signatures. Less collimated (but still high-velocity) flows are also present on
scales up to 5 kpc in most systems. The three galaxies in our sample with
obscured QSOs host higher velocity outflows than those in the three galaxies
with no evidence for an AGN. The peak outflow velocity in each of the QSOs is
in the range 1450-3350 km/s, and the highest velocities (2000-3000 km/s) are
seen only in ionized gas. The outflow energy and momentum in the QSOs are
difficult to produce from a starburst alone, but are consistent with the QSO
contributing significantly to the driving of the flow. Finally, when all gas
phases are accounted for, the outflows are massive enough to provide negative
feedback to star formation.


title:
Parameterized algorithms for the 2-clustering problem with minimum sum
  and minimum sum of squares objective functions

abstract:
  In the {\sc Min-Sum 2-Clustering} problem, we are given a graph and a
parameter $k$, and the goal is to determine if there exists a 2-partition of
the vertex set such that the total conflict number is at most $k$, where the
conflict number of a vertex is the number of its non-neighbors in the same
cluster and neighbors in the different cluster. The problem is equivalent to
{\sc 2-Cluster Editing} and {\sc 2-Correlation Clustering} with an additional
multiplicative factor two in the cost function. In this paper we show an
algorithm for {\sc Min-Sum 2-Clustering} with time complexity $O(n\cdot
2.619^{r/(1-4r/n)}+n^3)$, where $n$ is the number of vertices and $r=k/n$.
Particularly, the time complexity is $O^*(2.619^{k/n})$ for $k\in o(n^2)$ and
polynomial for $k\in O(n\log n)$, which implies that the problem can be solved
in subexponential time for $k\in o(n^2)$. We also design a parameterized
algorithm for a variant in which the cost is the sum of the squared
conflict-numbers. For $k\in o(n^3)$, the algorithm runs in subexponential
$O(n^3\cdot 5.171^{\theta})$ time, where $\theta=\sqrt{k/n}$.


title:
Model independent determination of the dark matter mass from direct
  detection experiments

abstract:
  Determining the dark matter (DM) mass is of paramount importance for
understanding dark matter. We present a novel parametrization of the DM speed
distribution which will allow the DM mass to be accurately measured using data
from Weakly Interacting Massive Particle (WIMP) direct detection experiments.
Specifically, we parametrize the natural logarithm of the speed distribution as
a polynomial in the speed v. We demonstrate, using mock data from upcoming
experiments, that by fitting the WIMP mass and interaction cross-section, along
with the polynomial coefficients, we can accurately reconstruct both the WIMP
mass and speed distribution. This new method is the first demonstration that an
accurate, unbiased reconstruction of the WIMP mass is possible without prior
assumptions about the distribution function. We anticipate that this technique
will be invaluable in the analysis of future experimental data.


title:
The influence of transcription factor competition on the relationship
  between occupancy and affinity

abstract:
  Transcription factors (TFs) are proteins that bind to specific sites on the
DNA and regulate gene activity. Identifying where TF molecules bind and how
much time they spend on their target sites is key for understanding
transcriptional regulation. It is usually assumed that the free energy of
binding of a TF to the DNA (the affinity of the site) is highly correlated to
the amount of time the TF remains bound (the occupancy of the site). However,
knowing the binding energy is not sufficient to infer actual binding site
occupancy. This mismatch between the occupancy predicted by the affinity and
the observed occupancy may be caused by various factors, such as TF abundance,
competition between TFs or the arrangement of the sites on the DNA. We
investigated the relationship between the affinity of a TF for a set of binding
sites and their occupancy. In particular, we considered the case of lac
repressor (lacI) in E.coli and performed stochastic simulations of the TF
dynamics on the DNA for various combinations of lacI abundance in competition
with TFs that contribute to macromolecular crowding. Our results showed that
for medium and high affinity sites, TF competition does not play a significant
role in genomic occupancy, except in cases when the abundance of lacI is
significantly increased or when a low-information content PWM was used.
Nevertheless, for medium and low affinity sites, an increase in TF abundance
(for both lacI or other molecules) leads to an increase in occupancy at several
sites. Keywords: facilitated diffusion, Position Weight Matrix, thermodynamic
equilibrium, motif information content, molecular crowding


title:
A Demonstration of Accurate Wide-field V-band Photometry Using a
  Consumer-grade DSLR Camera

abstract:
  The authors examined the suitability of using a Digital Single Lens Reflex
(DSLR) camera for stellar photometry and, in particular, investigated wide
field exposures made with minimal equipment for analysis of bright variable
stars. A magnitude-limited sample of stars was evaluated exhibiting a wide
range of (B-V) colors taken from four fields between Cygnus and Draco.
Experiments comparing green channel DSLR photometry with VT photometry of the
Tycho 2 catalogue showed very good agreement. Encouraged by the results of
these comparisons, a method for performing color-based transformations to the
more widely used Johnson V filter band was developed and tested. This method is
similar to that recommended for Tycho 2 VT data. The experimental evaluation of
the proposed method led to recommendations concerning the feasibility of high
precision DSLR photometry for certain types of variable star projects. Most
importantly, we have demonstrated that DSLR cameras can be used as accurate,
wide field photometers with only a minimal investment of funds and time.


title: An Analysis of the Long-term Photometric Behavior of epsilon Aurigae

abstract:
  The lure of a 50 percent reduction in light has brought a multitude of
observers and researchers to epsilon Aur every twenty-seven years, but few have
paid attention to the system outside of eclipse. As early as the late 1800s, it
was clear that the system undergoes some form of quasi-periodic variation
outside of totality, but few considered this effect in their research until the
mid-1950s. In this work we focus exclusively on the out-of-eclipse (OOE)
variations seen in this system. We have digitized twenty-seven sources of
historic photometry from eighty-one different observers. Two of these sources
provide twenty-seven years of inter-eclipse UBV photometry which we have
analyzed using modern period finding techniques. We have discovered the F-star
variations are multiperiodic with at least two periods that evolve in time at
delta(Period) approximately -1.5 day/year. These periods are detected when they
manifest as near-sinusoidal variations at 3,200-day intervals. We discuss our
work in an evolutionary context by comparing the behavior found in e Aur with
bona-fide supergiant and post-AGB stars of similar spectral type. Based upon
our qualitative comparison, we find the photometric behavior of the F-star in
the e Aur system is more indicative of supergiant behavior. Therefore the star
is more likely to be a "traditional supergiant" than a post-AGB object. We
encourage continued photometric monitoring of this system to test our
predictions.


title: Order-Preserving Suffix Trees and Their Algorithmic Applications

abstract:
  Recently Kubica et al. (Inf. Process. Let., 2013) and Kim et al. (submitted
to Theor. Comp. Sci.) introduced order-preserving pattern matching. In this
problem we are looking for consecutive substrings of the text that have the
same "shape" as a given pattern. These results include a linear-time
order-preserving pattern matching algorithm for polynomially-bounded alphabet
and an extension of this result to pattern matching with multiple patterns. We
make one step forward in the analysis and give an
$O(\frac{n\log{n}}{\log\log{n}})$ time randomized algorithm constructing suffix
trees in the order-preserving setting. We show a number of applications of
order-preserving suffix trees to identify patterns and repetitions in time
series.


title: General Fragmentation Trees

abstract:
  We show that the genealogy of any self-similar fragmentation process can be
encoded in a compact measured real tree. Under some Malthusian hypotheses, we
compute the fractal Hausdorff dimension of this tree through the use of a
natural measure on the set of its leaves. This generalizes previous work of
Haas and Miermont which was restricted to conservative fragmentation processes.


title: Invariants of ideals generated by pfaffians

abstract:
  Ideals generated by pfaffians are of interest in commutative algebra and
algebraic geometry, as well as in combinatorics. In this article we compute
multiplicity and Castelnuovo-Mumford regularity of pfaffian ideals of ladders.
We give explicit formulas for some families of ideals, and indicate a procedure
that allows to recursively compute the invariants of any pfaffian ideal of
ladder. Our approach makes an essential use of liaison theory.


title: Fused Mackey functors

abstract:
  Let $G$ be a finite group. In [HTW], Hambleton, Taylor and Williams have
considered the question of comparing Mackey functors for $G$ and biset functors
defined on subgroups of $G$ and bifree bisets as morphisms. This paper proposes
a different approach to this problem, from the point of view of various
categories of $G$-sets. In particular, the category of fused $G$-sets is
introduced, as well its category of spans. The fused Mackey functors for $G$
over a commutative ring $R$ are defined as $R$-linear functors from this
($R$-linearized) category of spans to $R$-modules. They form an abelian
subcategory of the category of Mackey functors for $G$ over $R$, equivalent
(for $R=Z$) to the category to the category of conjugation Mackey functors of
[HTW]. The category of fused Mackey functors is also equivalent to the category
of modules over the fused Mackey algebra, which is a quotient of the usual
Mackey algebra of $G$ over $R$. Reference: [HTW] I. Hambleton, L. R. Taylor,
and E. B. Williams. Mackey functors and bisets. Geom. Dedicata, 148:157--174,
2010.


title: Four band tunneling in bilayer graphene

abstract:
  The conductance, the transmission and the reflection probabilities through
rectangular potential barriers and pn-junctions are obtained for bilayer
graphene taking into account the four bands of the energy spectrum. We have
evaluated the importance of the skew hopping parameters {\gamma}3 and {\gamma}4
to these properties and show that for energies E>{\gamma}1/100 their effect is
negligible. For high energies two modes of propagation exist and we investigate
scattering between these modes. For perpendicular incidence both propagation
modes are decoupled and scattering between them is forbidden. This extends the
concept of pseudospin as defined within the two band approximation to a four
band model and corresponds to the (anti)symmetry of the wavefunctions under
in-plane mirroring. New transmission resonances are found that appear as sharp
peaks in the conductance which are absent in the two band approximation. The
application of an interlayer bias to the system: 1) breaks the pseudospin
structure, 2) opens a bandgap that results in a distinct feature of suppressed
transmission in the conductance, and 3) breaks the angular symmetry with
respect to normal incidence in the transmission and reflection.


title: Acoustic Calibration for the KM3NeT Pre-Production Module

abstract:
  The proposed large scale Cherenkov neutrino telescope KM3NeT will carry
photo-sensors on flexible structures, the detection units. The Mediterranean
Sea, where KM3NeT will be installed, constitutes a highly dynamic environment
in which the detection units are constantly in motion. Thus it is necessary to
monitor the exact sensor positions continuously to achieve the desired
resolution for the neutrino telescope. A common way to perform this monitoring
is the use of acoustic positioning systems with emitters and receivers based on
the piezoelectric effect. The acoustic receivers are attached to detection
units whereas the emitters are located at known positions on the sea floor.
There are complete commercial systems for this application with sufficient
precision. But these systems are limited in the use of their data and
inefficient as they were designed to perform only this single task. Several
working groups in the KM3NeT consortium are cooperating to custom-design a
positioning system for the specific requirements of KM3NeT. Most of the studied
solutions hold the possibility to extend the application area from positioning
to additional tasks like acoustic particle detection or monitoring of the
deep-sea acoustic environment. The KM3NeT Pre-Production Module (PPM) is a test
system to verify the correct operation and interoperability of the major
involved hardware and software components developed for KM3NeT. In the context
of the PPM, alternative designs of acoustic sensors including small
piezoelectric elements equipped with preamplifiers inside the same housing as
the optical sensors will be tested. These will be described in this article.


title: A Universe without expansion

abstract:
  We discuss a cosmological model where the universe shrinks rather than
expands during the radiation and matter dominated periods. Instead, the Planck
mass and all particle masses grow exponentially, with the size of atoms
shrinking correspondingly. Only dimensionless ratios as the distance between
galaxies divided by the atom radius are observable. Then the cosmological
increase of this ratio can also be attributed to shrinking atoms. We present a
simple model where the masses of particles arise from a scalar "cosmon" field,
similar to the Higgs scalar. The potential of the cosmon is responsible for
inflation and the present dark energy. Our model is compatible with all present
observations. While the value of the cosmon field increases, the curvature
scalar is almost constant during all cosmological epochs. Cosmology has no big
bang singularity. There exist other, equivalent choices of field variables for
which the universe shows the usual expansion or is static during the radiation
or matter dominated epochs. For those "field coordinates" the big bang is
singular. Thus the big bang singularity turns out to be related to a singular
choice of field coordinates.


title: Invertible polynomial mappings via Newton non-degeneracy

abstract:
  We prove a sufficient condition for the Jacobian problem in the setting of
real, complex and mixed polynomial mappings. This follows from the study of the
bifurcation locus of a mapping subject to a new Newton non-degeneracy
condition.


title:
Multi-sample Receivers Increase Information Rates for Wiener Phase Noise
  Channels

abstract:
  A waveform channel is considered where the transmitted signal is corrupted by
Wiener phase noise and additive white Gaussian noise (AWGN). A discrete-time
channel model is introduced that is based on a multi-sample receiver. Tight
lower bounds on the information rates achieved by the multi-sample receiver are
computed by means of numerical simulations. The results show that oversampling
at the receiver is beneficial for both strong and weak phase noise at high
signal-to-noise ratios. The results are compared with results obtained when
using other discrete-time models.


title: Distributed Overlay Anycast Table using Space filling curves

abstract:
  In this paper we present the \emph{Distributed Overlay Anycast Table}, a
structured overlay that implements application-layer anycast, allowing the
discovery of the closest host that is a member of a given group. One
application is in locality-aware peer-to-peer networks, where peers need to
discover low-latency peers participating in the distribution of a particular
file or stream. The DOAT makes use of network delay coordinates and a space
filling curve to achieve locality-aware routing across the overlay, and Bloom
filters to aggregate group identifiers. The solution is designed to optimise
both accuracy and query time, which are essential for real-time applications.
We simulated DOAT using both random and realistic node distributions. The
results show that accuracy is high and query time is low.


title: $\beta$-coalescents and stable Galton-Watson trees

abstract:
  Representation of coalescent process using pruning of trees has been used by
Goldschmidt and Martin for the Bolthausen-Sznitman coalescent and by Abraham
and Delmas for the $\beta(3/2,1/2)$-coalescent. By considering a pruning
procedure on stable Galton-Watson tree with $n$ labeled leaves, we give a
representation of the discrete $\beta(1+\alpha,1-\alpha)$-coalescent, with
$\alpha\in [1/2,1)$ starting from the trivial partition of the $n$ first
integers. The construction can also be made directly on the stable continuum
L{\'e}vy tree, with parameter $1/\alpha$, simultaneously for all $n$. This
representation allows to use results on the asymptotic number of coalescence
events to get the asymptotic number of cuts in stable Galton-Watson tree (with
infinite variance for the reproduction law) needed to isolate the root. Using
convergence of the stable Galton-Watson tree conditioned to have infinitely
many leaves, one can get the asymptotic distribution of blocks in the last
coalescence event in the $\beta(1+\alpha,1-\alpha)$-coalescent.


title:
ARAS: Fully algebraic Two-level domain decomposition precondition
  technique with approximation on course interfaces Fully

abstract:
  This paper focuses on the development of a two-level preconditioner based on
a fully algebraical enhancement of a Schwarz domain decomposition method. We
consider the purely divergence of a Restricted Additive Scwharz iterative
process leading to the preconditioner developped by X.-C. Cai and M. Sarkis in
SIAM Journal of Scientific Computing, Vol. 21 no. 2, 1999. The convergence of
vectorial sequence of traces of this process on the artificial interface can be
accelerated by an Aitken acceleration technique as proposed in the work of M.
Garbey and D. Tromeur-Dervout, in International Journal for Numerical Methods
in Fluids, Vol. 40, no. 12,2002. We propose a formulation of the Aitken-Schwarz
technique as a preconditioning technique called Aitken-RAS 1 . The Aitken
acceleration is performed in a reduced space to save computing or permit fully
algebraic computation of the accelerated solution without knowledge of the
underlying equations. A convergence study of the Aitken-RAS preconditioner is
proposed also application on industrial problem.


title: Semi Log-Concave Markov Diffusions

abstract:
  In this paper we intend to give a comprehensive approach of functional
inequalities for diffusion processes under some "curvature" assumptions. Our
notion of curvature coincides with the usual $\Gamma_2$ curvature of Bakry and
Emery in the case of a (reversible) drifted Brownian motion, but differs for
more general diffusion processes. Our approach using simple coupling arguments
together with classical stochastic tools, allows us to obtain new results, to
recover and to extend already known results, giving in many situations explicit
(though non optimal) bounds. In particular, we show new results for
gradient/semigroup commutation in the log concave case. Some new convergence to
equilibrium in the granular media equation is also exhibited.


title:
Exponential-Condition-Based Barrier Certificate Generation for Safety
  Verification of Hybrid Systems

abstract:
  A barrier certificate is an inductive invariant function which can be used
for the safety verification of a hybrid system. Safety verification based on
barrier certificate has the benefit of avoiding explicit computation of the
exact reachable set which is usually intractable for nonlinear hybrid systems.
In this paper, we propose a new barrier certificate condition, called
Exponential Condition, for the safety verification of semi-algebraic hybrid
systems. The most important benefit of Exponential Condition is that it has a
lower conservativeness than the existing convex condition and meanwhile it
possesses the property of convexity. On the one hand, a less conservative
barrier certificate forms a tighter over-approximation for the reachable set
and hence is able to verify critical safety properties. On the other hand, the
property of convexity guarantees its solvability by semidefinite programming
method. Some examples are presented to illustrate the effectiveness and
practicality of our method.


title: Galaxy Zoo: Motivations of Citizen Scientists

abstract:
  Citizen science, in which volunteers work with professional scientists to
conduct research, is expanding due to large online datasets. To plan projects,
it is important to understand volunteers' motivations for participating. This
paper analyzes results from an online survey of nearly 11,000 volunteers in
Galaxy Zoo, an astronomy citizen science project. Results show that volunteers'
primary motivation is a desire to contribute to scientific research. We
encourage other citizen science projects to study the motivations of their
volunteers, to see whether and how these results may be generalized to inform
the field of citizen science.


title: Scalable peer-to-peer streaming for live entertainment content

abstract:
  We present a system for streaming live entertainment content over the
Internet originating from a single source to a scalable number of consumers
without resorting to centralised or provider- provisioned resources. The system
creates a peer-to-peer overlay network, which attempts to optimise use of
existing capacity to ensure quality of service, delivering low start-up delay
and lag in playout of the live content. There are three main aspects of our
solution. Firstly, a swarming mechanism that constructs an overlay topology for
minimising propagation delays from the source to end consumers. Secondly, a
distributed overlay anycast system that uses a location-based search algorithm
for peers to quickly find the closest peers in a given stream. Finally, a novel
incentives mechanism that encourages peers to donate capacity even when the
user is not actively consuming content.


title:
Asymptotic formulas for eigenvalues and eigenfunctions of a new
  boundary-value-transmission problem

abstract:
  In this paper we are concerned with a new class of BVP' s consisting of
eigendependent boundary conditions and two supplementary transmission
conditions at one interior point. By modifying some techniques of classical
Sturm-Liouville theory and suggesting own approaches we find asymptotic
formulas for the eigenvalues and eigenfunction.


title: Right-angled Artin groups and Out(F_n) I: quasi-isometric embeddings

abstract:
  We construct quasi-isometric embeddings from right-angled Artin groups into
the outer automorphism group of a free group. These homomorphisms are in
analogy with those constructed in \cite{CLM}, where the target group is the
mapping class group of a surface. Toward this goal, we develop tools in the
free group setting that mirror those for surface groups as well as discuss
various analogs of subsurface projection; these may be of independent interest.


title:
Selfadjoint realization of boundary-value problems with interior
  singularities

abstract:
  The purpose of this paper is to investigate some spectral properties of
Sturm-Liouville type problems with interior singularities. Some of the
mathematical aspects necessary for developing own technique presented. By
applying this technique we construct some special solutions of the homogeneous
equation and present a formula and the existence conditions of Green's
function. Further based on this results and introducing operator treatment in
adequate Hilbert space we derive the resolvent operator and prove
selfadjointness of the considered problem.


title: Response of liquid xenon to Compton electrons down to 1.5 keV

abstract:
  The response of liquid xenon to low-energy electronic recoils is relevant in
the search for dark-matter candidates which interact predominantly with atomic
electrons in the medium, such as axions or axion-like particles, as opposed to
weakly interacting massive particles which are predicted to scatter with atomic
nuclei. Recently, liquid-xenon scintillation light has been observed from
electronic recoils down to 2.1 keV, but without applied electric fields that
are used in most xenon dark matter searches. Applied electric fields can reduce
the scintillation yield by hindering the electron-ion recombination process
that produces most of the scintillation photons. We present new results of
liquid xenon's scintillation emission in response to electronic recoils as low
as 1.5 keV, with and without an applied electric field. At zero field, a
reduced scintillation output per unit deposited energy is observed below 10
keV, dropping to nearly 40% of its value at higher energies. With an applied
electric field of 450 V/cm, we observe a reduction of the scintillation output
to about 75% relative to the value at zero field. We see no significant energy
dependence of this value between 1.5 keV and 7.8 keV. With these results, we
estimate the electronic-recoil energy thresholds of ZEPLIN-III, XENON10,
XENON100, and XMASS to be 2.8 keV, 2.5 keV, 2.3 keV, and 1.1 keV, respectively,
validating their excellent sensitivity to low-energy electronic recoils.


title: Green's function for Sturm-Liouville problem

abstract:
  The purpose of this study is to investigate a new class of boundary value
transmission problems (BVTP's) for Sturm-Liouville equation on two separate
intervals. We introduce modified inner product in direct sum space
$L_{2}[a,c)\oplus L_{2}(c,b]\oplus\mathbb{C}^{2}$ and define symmetric linear
operator in it such a way that the considered problem can be interpreted as an
eigenvalue problem of this operator. Then by suggesting an own approaches we
construct Green's function for problem under consideration and find the
resolvent function for corresponding inhomogeneous problem.


title: Expansion Theorem for Sturm-Liouville problems transmission conditions

abstract:
  The purpose of this paper is to extend some spectral properties of regular
Sturm-Liouville problems to the special type discontinuous boundary-value
problem, which consists of a Sturm-Liouville equation together with
eigenparameter-dependent boundary conditions and two supplementary transmission
conditions. We construct the resolvent operator and Green's function and prove
theorems about expansions in terms of eigenfunctions in modified Hilbert space
$L_{2}[a, b]$. \vskip0.3cm\noindent Keywords: Boundary-value problems,
transmission conditions, Resolvent operator, expansion theorem.


title:
Sharp regularity near an absorbing boundary for solutions to second
  order SPDEs in a half-line with constant coefficients

abstract:
  We prove that the weak version of the SPDE problem \begin{align*} dV_{t}(x) &
= [-\mu V_{t}'(x) + \frac{1}{2} (\sigma_{M}^{2} + \sigma_{I}^{2})V_{t}"(x)]dt -
\sigma_{M} V_{t}'(x)dW^{M}_{t}, \quad x > 0, \\ V_{t}(0) &= 0 \end{align*} with
a specified bounded initial density, $V_{0}$, and $W$ a standard Brownian
motion, has a unique solution in the class of finite-measure valued processes.
The solution has a smooth density process which has a probabilistic
representation and shows degeneracy near the absorbing boundary. In the
language of weighted Sobolev spaces, we describe the precise order of
integrability of the density and its derivatives near the origin, and we relate
this behaviour to a two-dimensional Brownian motion in a wedge whose angle is a
function of the ratio $\sigma_{M}/\sigma_{I}$. Our results are sharp: we
demonstrate that better regularity is unattainable.


title: The mapping space of unbounded differential graded algebras

abstract:
  In this paper, we give a concrete description of the higher homotopy groups
(n>0) of the mapping space Map_{Alg}(R,S) for R and S unbounded differential
graded algebras (DGA) over a commutative ring k. In the connective case, we
describe the relation between the higher (negative) Hochschild cohomology
$HH^{-n+1}(R,S)$ and higher homotopy groups $\pi_{n} Map_{Alg}(R,S)$, when
$n>1$.


title: Gravitational lensing evidence against extended dark matter halos

abstract:
  It is generally thought that galaxies are embedded in dark matter halos
extending well beyond their luminous matter. The existence of these galactic
halos is mainly derived from the larger than expected velocities of stars and
gas in the outskirts of spiral galaxies. Much less is known about dark matter
around early-type (elliptical or lenticular) galaxies. We use gravitational
lensing to derive the masses of early-type galaxies deflecting light of
background quasars. This provides a robust measurement of the total mass within
the Einstein ring, a circle whose diameter is comparable to the separation of
the different quasar images. We find that the mass-to-light ratio of the
lensing galaxies does not depend on radius, from inner galactic regions out to
several half-light radii. Moreover, its value does not exceed the value
predicted by stellar population models by more than a factor two, which may be
explained by baryonic dark matter alone, without any need for exotic matter.
Our results thus suggest that, if dark matter is present in early-type
galaxies, its amount does not exceed the amount of luminous matter and its
density follows that of luminous matter, in sharp contrast to what is found
from rotation curves of spiral galaxies.


title: Analysis of $\gamma^\ast \Lambda \to \Sigma^0$ transition in QCD

abstract:
  The $\gamma^\ast \Lambda \to \Sigma^0$ transition form factors are
investigated within the light--cone QCD sum rules method. Using the most
general form of the interpolating current of $\Sigma^0$ baryon and the
distribution amplitudes of $\Lambda$ baryon we calculate the $Q^2$ dependence
of the electromagnetic form factors. Our result are compared with the
predictions of the covariant spectator quark model.


title:
Modified Expansion Theorem for Sturm-Liouville problem with transmission
  conditions

abstract:
  This paper is devoted to the derivation of expansion a associated with a
discontinuous Sturm-Liouville problems defined on $[-\pi, 0)\cup(0,\pi]$. We
derive an eigenfunction expansion theorem for the Green's function of the
problem as well as a theorem of uniform convergence of a certain class of
functions.


title:
Spectro-photometric variability of quasars caused by lensing of diffuse
  massive substructure: Consequences on flux anomaly and precise astrometric
  measurements

abstract:
  We investigate the spectro-photometric variability of quasars due to lensing
of small mass substructure (from several tens to several hundreds solar
masses). The aim of this paper is to explore the milli/microlensing influence
on the flux anomaly observed between images of a lensed quasar in different
spectral bands and possible influence of small mass structure lensing of
non-macrolensed quasars.We find that spectro-photometric variability may be
also caused by lensing of small mass diffuse structure and can produce the flux
anomaly which is sometimes seen in different images of a lensed quasar.
Additionally, we found that the lensing by small mass diffuse structure may
produce significant changes in photo-center position of a quasar, and sometimes
can split or deviate images of one source that can be detected as separate from
the scale from 0.1 to several milliarcseconds. This can be measured ith
Gaialike space astrometric missions. We point out a special case where a low
redshifted deflector zd = 0.01 is lensing a high redshifted source, for which
the variability in the flux and photocenter (several milliarcseconds) may be
detected on a relatively short time scale.


title:
Circular band formation for incompressible viscous fluid--rigid particle
  mixtures in a rotating cylinder

abstract:
  In this paper we have investigated a circular band formation of fluid-rigid
particle mixtures in a fully filled cylinder horizontally rotating about its
cylinder axis by direct numerical simulation. These phenomena are modeled by
the Navier-Stokes equations coupled to the Euler-Newton equations describing
the rigid solid motion of the non-neutrally particles. The formation of
circular bands studied in this paper is not resulted by mutual interaction
between the particles and the periodic inertial waves in the cylinder axis
direction (as suggested in Phys. Rev. E, 72, 021407 (2005)), but due to the
interaction of particles. When a circular band is forming, the part of the band
formed by the particles moving downward becomes more compact due to the
particle interaction strengthened by the downward acceleration from the
gravity. The part of a band formed by the particles moving upward is always
loosening up due to the slow down of the particle motion by the counter effect
of the gravity. To form a compact circular band (not a loosely one), enough
particles are needed to interact among themselves continuously through the
entire circular band at a rotating rate so that the upward diffusion of
particles can be balanced by the compactness process when these particles
moving downward.


title:
VLBI observations of the shortest orbital period black hole binary, MAXI
  J1659-152

abstract:
  The X-ray transient MAXI J1659-152 was discovered by Swift/BAT and it was
initially identified as a GRB. Soon its Galactic origin and binary nature were
established. There exists a wealth of multi-wavelength monitoring data for this
source, providing a great coverage of the full X-ray transition in this
candidate black hole binary system. We obtained two epochs of European VLBI
Network (EVN) electronic-VLBI (e-VLBI) and four epochs of Very Long Baseline
Array (VLBA) data of MAXI J1659-152 which show evidence for outflow in the
early phases. The overall source properties (polarization, milliarcsecond-scale
radio structure, flat radio spectrum) are described well with the presence of a
compact jet in the system through the transition from the hard-intermediate to
the soft X-ray spectral state. The apparent dependence of source size and the
radio core position on the observed flux density (luminosity dependent core
shift) support this interpretation as well. We see no evidence for major
discrete ejecta during the outburst. For the source proper motion we derive 2
sigma upper limits of 115 microas/day in right ascension, and 37 microas/day in
declination, over a time baseline of 12 days. These correspond to velocities of
1400 km/s and 440 km/s, respectively, assuming a source distance of 7 kpc.


title:
Transient Charge and Energy Balance in Graphene Induced by Ultrafast
  Photoexcitation

abstract:
  Ultrafast optical pump-probe spectroscopy measurement on monolayer graphene
observes significant optical nonlinearities. We show that strongly photoexcited
graphene monolayers with 35 fs pulses quasi-instantaneously build up a
broadband, inverted Dirac fermion population. Optical gain emerges and directly
manifests itself via a negative conductivity at the near-infrared region for
the first 200fs, where stimulated emission completely compensates absorption
loss in the graphene layer. To quantitatively investigate this transient,
extremely dense photoexcited Dirac-fermion state, we construct a
two-chemical-potential model, in addition to a time-dependent transient carrier
temperature above lattice temperature, to describe the population inverted
electronic state metastable on the time scale of tens of femtoseconds generated
by a strong exciting pulse. The calculated transient optical conductivity
reveals a complete bleaching of absorption, which sets the saturation density
during the pulse propagation. Particularly, the model calculation reproduces
the negative optical conductivity at lower frequencies in the states close to
saturation, corroborating the observed femtosecond stimulated emission and
optical gain in the wide near-infrared window.


title:
Superstripes and the excitation spectrum of a spin-orbit-coupled
  Bose-Einstein condensate

abstract:
  Using Bogoliubov theory we calculate the excitation spectrum of a spinor
Bose-Einstein condensed gas with equal Rashba and Dresselhaus spin-orbit
coupling in the stripe phase. The emergence of a double gapless band structure
is pointed out as a key signature of Bose-Einstein condensation and of the
spontaneous breaking of translational invariance symmetry. In the long
wavelength limit the lower and upper branches exhibit, respectively, a clear
spin and density nature. For wave vectors close to the first Brillouin zone,
the lower branch acquires an important density character responsible for the
divergent behavior of the structure factor and of the static response function,
reflecting the occurrence of crystalline order. The sound velocities are
calculated as functions of the Raman coupling for excitations propagating
orthogonal and parallel to the stripes. Our predictions provide new
perspectives for the identification of supersolid phenomena in ultracold atomic
gases.


title: Bioeconomic Perspectives to an Optimal Control Dengue Model

abstract:
  A model with six mutually-exclusive compartments related to dengue is
studied. Three vector control tools are considered: insecticides (larvicide and
adulticide) and mechanical control. The basic reproduction number associated to
the model is presented. The problem is studied using an optimal control
approach. The human data is based on the dengue outbreak that occurred in Cape
Verde. Control measures are simulated in different scenarios and their
consequences analyzed.


title:
The development of the architecture of Distributed Network Intrusion
  Detection System (D-NIDS)

abstract:
  This paper presents the development of the architecture of Distributed
Network Intrusion Detection System.


title: Large scale citation matching using Apache Hadoop

abstract:
  During the process of citation matching links from bibliography entries to
referenced publications are created. Such links are indicators of topical
similarity between linked texts, are used in assessing the impact of the
referenced document and improve navigation in the user interfaces of digital
libraries. In this paper we present a citation matching method and show how to
scale it up to handle great amounts of data using appropriate indexing and a
MapReduce paradigm in the Hadoop environment.


title:
Parameterized Approximability of Maximizing the Spread of Influence in
  Networks

abstract:
  In this paper, we consider the problem of maximizing the spread of influence
through a social network. Given a graph with a threshold value~$thr(v)$
attached to each vertex~$v$, the spread of influence is modeled as follows: A
vertex~$v$ becomes "active" (influenced) if at least $thr(v)$ of its neighbors
are active. In the corresponding optimization problem the objective is then to
find a fixed number of vertices to activate such that the number of activated
vertices at the end of the propagation process is maximum. We show that this
problem is strongly inapproximable in fpt-time with respect to (w.r.t.)
parameter $k$ even for very restrictive thresholds. In the case that the
threshold of each vertex equals its degree, we prove that the problem is
inapproximable in polynomial time and it becomes $r(n)$-approximable in
fpt-time w.r.t. parameter $k$ for any strictly increasing function $r$.
  Moreover, we show that the decision version is W[1]-hard w.r.t. parameter $k$
but becomes fixed-parameter tractable on bounded degree graphs.


title:
Challenges in the capture and dissemination of measurements from
  high-speed networks

abstract:
  The production of a large-scale monitoring system for a high-speed network
leads to a number of challenges. These challenges are not purely techinical but
also socio-political and legal. The number of stakeholders in a such a
monitoring activity is large including the network operators, the users, the
equipment manufacturers and of course the monitoring researchers. The MASTS
project (Measurement at All Scales in Time and Space) was created to instrument
the high-speed JANET Lightpath network, and has been extended to incorporate
other paths supported by JANET(UK).
  Challenges the project has faced have included: simple access to the network;
legal issues involved in the storage and dissemination of the captured
information, which may be personal; the volume of data captured and the rate at
which this data appears at store. To this end the MASTS system will have
established four monitoring points each capturing packets on a high speed link.
Traffic header data will be continuously collected, anonymised, indexed, stored
and made available to the research community. A legal framework for the capture
and storage of network measurement data has been developed which allows the
anonymised IP traces to be used for research pur poses.


title: Leading singularities and off-shell conformal integrals

abstract:
  The three-loop four-point function of stress-tensor multiplets in N=4 super
Yang-Mills theory contains two so far unknown, off-shell, conformal integrals,
in addition to the known, ladder-type integrals. In this paper we evaluate the
unknown integrals, thus obtaining the three-loop correlation function
analytically. The integrals have the generic structure of rational functions
multiplied by (multiple) polylogarithms. We use the idea of leading
singularities to obtain the rational coefficients, the symbol - with an
appropriate ansatz for its structure - as a means of characterising multiple
polylogarithms, and the technique of asymptotic expansion of Feynman integrals
to obtain the integrals in certain limits. The limiting behaviour uniquely
fixes the symbols of the integrals, which we then lift to find the
corresponding polylogarithmic functions. The final formulae are numerically
confirmed. The techniques we develop can be applied more generally, and we
illustrate this by analytically evaluating one of the integrals contributing to
the same four-point function at four loops. This example shows a connection
between the leading singularities and the entries of the symbol.


title:
Introducing nanoengineering and nanotechnology to the first year
  students through an interactive seminar course

abstract:
  We report a first year seminar course on nanoengineering, which provides a
unique opportunity to get exposed to the bottom-up approach and novel
nanotechnology applications in an informal small class setting early in the
undergraduate engineering education. Our objective is not only to introduce the
fundamentals and applications of nanoengineering but also the issues related to
ethics, environmental and societal impact of nanotechnology used in
engineering. To make the course more interactive, laboratory tours for
microfabrication facility, microscopy facility, and nanoscale laboratory at the
University of Iowa are included, which inculcate the practical feel of the
technology. The course also involves active student participation through
weekly student presentations, highlighting topics of interest to this field,
with the incentive of "nano is everywhere" Final term papers submitted by the
students involve a rigorous technology analysis through various perspectives.
Furthermore, a student based peer review process is developed which helps them
to improve technical writing skills, as well as address the ethical issues of
academic honesty while reviewing and getting introduced to a new aspect of the
area presented by their colleagues. Based on the chosen paper topics and
student ratings, the student seemed motivated to learn about the novel area
introduced to them through theoretical, computational and experimental aspects
of the bottom-up approach.


title: Intrinsically knotted graphs with 21 edges

abstract:
  We show that the 14 graphs obtained by $\nabla\mathrm{Y}$ moves on K_7
constitute a complete list of the minor minimal intrinsically knotted graphs on
21 edges. We also present evidence in support of a conjecture that the 20 graph
Heawood family, obtained by a combination of $\nabla\mathrm{Y}$ and
$\mathrm{Y}\nabla$ moves on K_7, is the list of graphs of size 21 that are
minor minimal with respect to the property not 2--apex.


title: The Phenomenology of Right Handed Neutrinos

abstract:
  Neutrinos are the only particles in the Standard Model of particle physics
that have only been observed with left handed chirality to date. If right
handed neutrinos exist, they could be responsible for several phenomena that
have no explanation within the Standard Model, including neutrino oscillations,
the baryon asymmetry of the universe, dark matter and dark radiation. After a
pedagogical introduction, we review recent progress in the phenomenology of
right handed neutrinos. We in particular discuss the mass ranges suggested by
hints for neutrino oscillation anomalies and dark radiation (eV), sterile
neutrino dark matter scenarios (keV) and experimentally testable theories of
baryogenesis (GeV to TeV). We summarize constraints from theoretical
considerations, laboratory experiments, astrophysics and cosmology for each of
these.


title:
Perturbation analysis for an imperfect interface crack problem using
  weight function techniques

abstract:
  We analyse a problem of anti-plane shear in a bi-material plane containing a
semi-infinite crack situated on a soft imperfect interface. The plane also
contains a small thin inclusion (for instance an ellipse with high
eccentricity) whose influence on the propagation of the main crack we
investigate. An important element of our approach is the derivation of a new
weight function (a special solution to a homogeneous boundary value problem) in
the imperfect interface setting. The weight function is derived using Fourier
transform and Wiener-Hopf techniques and allows us to obtain an expression for
an important constant (which may be used in a fracture criterion) that
describes the leading order of tractions near the crack tip for the unperturbed
problem. We present computations that demonstrate how this constant varies
depending on the extent of interface imperfection and contrast in material
stiffness. We then perform perturbation analysis to derive an expression for
the change in the leading order of tractions near the tip of the main crack
induced by the presence of the small defect, whose sign can be interpreted as
the inclusion's presence having an amplifying or shielding effect on the
propagation of the main crack.


title: One example of general unidentifiable tensors

abstract:
  The identifiability of parameters in a probabilistic model is a crucial
notion in statistical inference. We prove that a general tensor of rank 8 in
C^3\otimes C^6\otimes C^6 has at least 6 decompositions as sum of simple
tensors, so it is not 8-identifiable. This is the highest known example of
balanced tensors of dimension 3, which are not k-identifiable, when k is
smaller than the generic rank.


title: Refined methods for the identifiability of tensors

abstract:
  We prove that the general tensor of size 2^n and rank k has a unique
decomposition as the sum of decomposable tensors if k<= 0.9997 (2^n)/(n+1) (the
constant 1 being the optimal value). Similarly, the general tensor of size 3^n
and rank k has a unique decomposition as the sum of decomposable tensors if k<=
0.998 (3^n)/(2n+1) (the constant 1 being the optimal value).
  Some results of this flavor are obtained for tensors of any size, but the
explicit bounds obtained are weaker.


title:
Quantum Shock Waves and Population Inversion in Collisions of Ultracold
  Atomic Clouds

abstract:
  Using Time-Dependent Density Matrix Renormalization Group (TDMRG) we study
the collision of one-dimensional atomic clouds confined in a harmonic trap and
evolving with the Lieb-Liniger Hamiltonian. It is observed that the motion is
essentially periodic with the clouds bouncing elastically, at least on the time
scale of the first few oscillations that can be resolved with high accuracy.
This is in agreement with the results of the "quantum Newton cradle" experiment
of Kinoshita et al. [Nature 440, 900 (2006)]. We compare the results for the
density profile against a hydrodynamic description, or generalized nonlinear
Schr\"odinger equation, with the pressure term taken from the Bethe Ansatz
solution of the Lieb-Liniger model. We find that hydrodynamics can describe the
breathing mode of a harmonically trapped cloud for arbitrary long times while
it breaks down almost immediately for the collision of two clouds due to the
formation of shock waves (gradient catastrophe). In the case of the clouds'
collision TDMRG alone allows to extract the oscillation period which is found
to be measurably different from the breathing mode period. Concomitantly with
the shock waves formation we observe a local energy distribution typical of
population inversion, i.e., an effective negative temperature. Our results are
an important step towards understanding the hydrodynamics of quantum many-body
systems out of equilibrium and the role of integrability in their dynamics.


title: Is there life beyond Quantum Mechanics?

abstract:
  We formulate physically-motivated axioms for a physical theory which for
systems with a finite number of degrees of freedom uniquely lead to Quantum
Mechanics as the only nontrivial consistent theory. Complex numbers and the
existence of the Planck constant common to all systems arise naturally in this
approach. The axioms are divided into two groups covering kinematics and basic
measurement theory respectively. We show that even if the second group of
axioms is dropped, there are no deformations of Quantum Mechanics which
preserve the kinematic axioms. Thus any theory going beyond Quantum Mechanics
must represent a radical departure from the usual a priori assumptions about
the laws of Nature.


title:
Post-Sphaleron Baryogenesis and an Upper Limit on the
  Neutron-Antineutron Oscillation Time

abstract:
  A recently proposed scenario for baryogenesis, called post--sphaleron
baryogenesis (PSB) is discussed within a class of quark--lepton unified
framework based on the gauge symmetry SU(2)_L x SU(2)_R x SU(4)_c realized in
the multi--TeV scale. The baryon asymmetry of the universe in this model is
produced below the electroweak phase transition temperature after the
sphalerons have decoupled from the Hubble expansion. These models embed
naturally the seesaw mechanism for neutrino masses, and predict color-sextet
scalar particles in the TeV range which may be accessible to the LHC
experiments. A necessary consequence of this scenario is the baryon number
violating \Delta B=2 process of neutron--antineutron (n-\bar{n}) oscillations.
In this paper we show that the constraints of PSB, when combined with the
neutrino oscillation data and restrictions from flavor changing neutral
currents mediated by the colored scalars imply an upper limit on the n-\bar{n}
oscillation time of 5 x 10^{10} sec. regardless of the quark--lepton
unification scale. If this scale is relatively low, in the (200-250) TeV range,
\tau_{n-\bar{n}} is predicted to be less than 10^{10} sec., which is accessible
to the next generation of proposed experiments.


title: A Partial Decode-Forward Scheme For A Network with N relays

abstract:
  We study a discrete-memoryless relay network consisting of one source, one
destination and N relays, and design a scheme based on partial decode-forward
relaying. The source splits its message into one common and N+1 private parts,
one intended for each relay. It encodes these message parts using Nth-order
block Markov coding, in which each private message part is independently
superimposed on the common parts of the current and N previous blocks. Using
simultaneous sliding window decoding, each relay fully recovers the common
message and its intended private message with the same block index, then
forwards them to the following nodes in the next block. This scheme can be
applied to any network topology. We derive its achievable rate in a compact
form. The result reduces to a known decode-forward lower bound for an N-relay
network and partial decode-forward lower bound for a two-level relay network.
We then apply the scheme to a Gaussian two-level relay network and obtain its
capacity lower bound considering power constraints at the transmitting nodes.


title:
Trajectory statistics of confined L\'{e}vy flights and Boltzmann-type
  equilibria

abstract:
  We analyze a specific class of random systems that are driven by a symmetric
L\'{e}vy stable noise, where Langevin representation is absent. In view of the
L\'{e}vy noise sensitivity to environmental inhomogeneities, the pertinent
random motion asymptotically sets down at the Boltzmann-type equilibrium,
represented by a probability density function (pdf) $\rho_*(x) \sim \exp [-\Phi
(x)]$. Here, we infer pdf $\rho (x,t)$ based on numerical path-wise simulation
of the underlying jump-type process. A priori given data are jump transition
rates entering the master equation for $\rho (x,t)$ and its target pdf
$\rho_*(x)$. To simulate the above processes, we construct a suitable
modification of the Gillespie algorithm, originally invented in the chemical
kinetics context. We exemplified our algorithm simulating different jump-type
processes and discuss the dynamics of real physical systems where it can be
useful.


title:
Magnetism driven ferroelectricity above liquid nitrogen temperature in
  Y2CoMnO6

abstract:
  We report multiferroic behavior in double perovskite Y2CoMnO6 with
ferroelectric transition temperature Tc = 80K. The origin of ferroelectricity
is associated with magnetic ordering of Co2+ and Mn4+ moments in a
up-up-down-down arrangement. The saturation polarization and magnetization are
estimated to be 65 uC/m2 and 6.2 Bohr magneton/f.u. respectively. The
magnetoelectric coupling parameter, on the other hand, is small as a 5 Tesla
field suppresses the electric polarization by only ~8%. This is corroborated
with observed hysteretic behaviour at 5K that remains unsaturated even upto 7
Tesla. A model based on exchange-striction is proposed to explain the observed
high temperature ferroelectricity.


title:
Global weak solutions to the inhomogeneous Navier-Stokes-Vlasov
  equations

abstract:
  A fluid-particle system of the inhomogeneous Navier-Stokes equations and
Vlasov equation in the three dimensional space is considered in this paper. The
coupling arises from the drag force in the fluid equations and the acceleration
in the Vlasov equation. An initial-boundary value problem is studied in a
bounded domain with large data. The existence of global weak solutions is
established through an approximation scheme, energy estimates, and weak
convergence.


title:
Coupled BEM-FEM for the convected Helmholtz equation with non-uniform
  flow in a bounded domain

abstract:
  We consider the convected Helmholtz equation modeling linear acoustic
propagation at a fixed frequency in a subsonic flow around a scattering object.
The flow is supposed to be uniform in the exterior domain far from the object,
and potential in the interior domain close to the object. Our key idea is the
reformulation of the original problem using the Prandtl--Glauert transformation
on the whole flow domain, yielding (i) the classical Helmholtz equation in the
exterior domain and (ii) an anisotropic diffusive PDE with skew-symmetric
first-order perturbation in the interior domain such that its transmission
condition at the coupling boundary naturally fits the Neumann condition from
the classical Helmholtz equation. Then, efficient off-the-shelf tools can be
used to perform the BEM-FEM coupling, leading to two novel variational
formulations for the convected Helmholtz equation. The first formulation
involves one surface unknown and can be affected by resonant frequencies, while
the second formulation avoids resonant frequencies and involves two surface
unknowns. Numerical simulations are presented to compare the two formulations.