title:
Derivation of line shape function in the optical conductivity by a new
  diagram method

abstract:
  A new diagram method to derive line shape function in the optical
conductivity formula is introduced and the result obtained applying the method
to an electron-phonon system is compared with that derived using the
projection-reduction method. The result satisfies the population criterion,
which states that the distribution functions for electrons and phonons should
be combined in multiplicative forms, and gives physical intuition to quantum
dynamics of electrons in a solid. This method can be called the "KC diagram"
method because it originates from the proper application of the Kang-Choi
reduction identity and a state-dependent projection operator.


title:
Bright "merger-nova" from the remnant of a neutron star binary merger: A
  signature of a newly born, massive, millisecond magnetar

abstract:
  A massive millisecond magnetar may survive a merger of a neutron star (NS)
binary, which would continuously power the merger ejecta. We develop a generic
dynamic model for the merger ejecta with energy injection from the central
magnetar. The ejecta emission (the "merger-nova") powered by the magnetar peaks
in the UV band and the peak of lightcurve progressively shifts to an earlier
epoch with increasing frequency. A magnetar-powered mergernova could have an
optical peak brightness comparable to a supernova, which is a few tens or
hundreds times brighter than the radioactive-powered merger-novae (the
so-called macro-nova or kilo-nova). On the other hand, such a merger-nova would
peak earlier and have a significantly shorter duration than that of a
supernova. An early collapse of the magnetar could suppress the brightness of
the optical emission and shorten its duration. Such
millisecond-magnetar-powered merger-novae may be detected from NS-NS merger
events without an observed short gamma-ray burst, and could be a bright
electromagnetic counterpart for gravitational wave bursts due to NS-NS mergers.
If detected, it suggests that the merger leaves behind a massive NS, which has
important implications for the equation-of-state of nuclear matter.


title: Rotation number of primitive vector sequences

abstract:
  We give a formula on the rotation number of a sequence of primitive vectors,
which is a generalization of the formula on the rotation number of a unimodular
sequence in \cite{Higashitani and Masuda}.


title: Measuring Antimatter Gravity with Muonium

abstract:
  We consider a measurement of the gravitational acceleration of antimatter,
gbar, using muonium. A monoenergetic, low-velocity, horizontal muonium beam
will be formed from a surface-muon beam using a novel technique and directed at
an atom interferometer. The measurement requires a precision three-grating
interferometer: the first grating pair creates an interference pattern which is
analyzed by scanning the third grating vertically using piezo actuators.
State-of-the-art nanofabrication can produce the needed membrane grating
structure in silicon nitride or ultrananoscrystalline diamond. With 100 nm
grating pitch, a 10% measurement of gbar can be made using some months of
surface-muon beam time. This will be the first gravitational measurement of
leptonic matter, of 2nd-generation matter and, possibly, the first measurement
of the gravitational acceleration of antimatter.

categories: physics.ins-det astro-ph.CO hep-ex physics.atom-ph


title: Global Dynamics of a Stochastic Neuronal Oscillator

abstract:
  Nonlinear oscillators have been used to model neurons that fire periodically
in the absence of input. These oscillators, which are called neuronal
oscillator, share some common response structures with other biological
oscillations. In this study, we analyze the dependence of the global dynamics
of an impulse-driven stochastic neuronal oscillator on the relaxation rate to
the limit cycle, the strength of the intrinsic noise, and the impulsive input
parameters. To do this, we use a Markov operator that both reflects the density
evolution of the oscillator and is an extension of the phase transition curve,
which describes the phase shift due to a single isolated impulse. Previously,
we derived the Markov operator for the finite relaxation rate that describes
the dynamics of the entire phase plane. Here, we construct a Markov operator
for the infinite relaxation rate that describes the stochastic dynamics
restricted to the limit cycle. In both cases, the response of the stochastic
neuronal oscillator to time-varying impulses is described by a product of
Markov operators. Furthermore, we calculate the number of spikes between two
consecutive impulses to relate the dynamics of the oscillator to the number of
spikes per unit time and the interspike interval density. Specifically, we
analyze the dynamics of the number of spikes per unit time based on the
properties of the Markov operators. Each Markov operator can be decomposed into
stationary and transient components based on the properties of the eigenvalues
and eigenfunctions. This allows us to evaluate the difference in the number of
spikes per unit time between the stationary and transient responses of the
oscillator, which we show to be based on the dependence of the oscillator on
past activity. Our analysis shows how the duration of the past neuronal
activity depends on the relaxation rate, the noise strength and the input
parameters.


title: Counting composites with two strong liars

abstract:
  The strong probable primality test is an important practical tool for
discovering prime numbers. Its effectiveness derives from the following fact:
for any odd composite number $n$, if a base $a$ is chosen at random, the
algorithm is unlikely to claim that $n$ is prime. If this does happen we call
$a$ a liar. In 1986, Erd\H{o}s and Pomerance computed the normal and average
number of liars, over all $n \leq x$. We continue this theme and use a variety
of techniques to count $n \leq x$ with exactly two strong liars, those being
the $n$ for which the strong test is maximally effective. We evaluate this
count asymptotically and give an improved algorithm to determine it exactly. We
also provide asymptotic counts for the restricted case in which $n$ has two
prime factors, and for the $n$ with exactly two Euler liars.


title: Algebraic spiral solutions of 2d incompressible Euler

abstract:
  We consider self-similar solutions of the 2d incompressible Euler equations.
We construct a class of solutions with vorticity forming algebraic spirals near
the origin, in analogy to vortex sheets rolling up into algebraic spirals.


title: Investigating Close-in Exoplanets through Transit Observations

abstract:
  Through the international collaborators, we recently established a network of
existing and working meter-class telescopes to look for planetary transit
events. As a first step, we focus on the TrES3 system, and conclude that there
could be some level of transit timing variations.


title:
Hot-electron refluxing enhanced relativistic transparency of overdense
  plasmas

abstract:
  A new phenomenon of enhancing the relativistic transparency of overdense
plasmas by the influence of hot-electron refluxing has been found via
particle-in-cell simulations. When a p-polarized laser pulse, with intensity
below the self-induced-transparency (SIT) threshold, obliquely irradiates a
thin overdense plasma, the initially opaque plasma would become transparent
after a time interval which linearly relies on the thickness of the plasma.
This phenomenon can be interpreted by the influence of hot-electron refluxing.
As the laser intensity is higher than the SIT threshold, the penetration
velocity of the laser in the plasma is enhanced when the refluxing is
presented. Simulation data with ion motion considered is also consistent with
the assumption that hot-electron refluxing enhances transparency. These results
have potential applications in laser shaping.


title: Environments of Extended Radio Sources in the ATLBS Survey

abstract:
  We present a study of the environments of extended radio sources in the
Australia Telescope Low Brightness Survey (ATLBS). The radio sources were
selected from the Extended Source Sample (ATLBS-ESS), which is a well defined
sample containing the most extended of radio sources in the ATLBS sky survey
regions. The environments were analyzed using 4-m CTIO Blanco telescope
observations carried out for ATLBS fields in the SDSS ${\rm r}^{\prime}$ band.
We have estimated the properties of the environments using smoothed density
maps derived from galaxy catalogs constructed using these optical imaging data.
The angular distribution of galaxy density relative to the axes of the radio
sources has been quantified by defining anisotropy parameters that are
estimated using a new method presented here. Examining the anisotropy
parameters for a sub-sample of extended double radio sources that includes all
sources with pronounced asymmetry in lobe extents, we find good evidence for
environmental anisotropy being the dominant cause for lobe asymmetry in that
higher galaxy density occurs almost always on the side of the shorter lobe, and
this validates the usefulness of the method proposed and adopted here. The
environmental anisotropy parameters have been used to examine and compare the
environments of FRI and FRII radio sources in two redshift regimes ($z<0.5$ and
$z>0.5$). Wide-angle tail sources and Head-tail sources lie in the most
overdense environments. The Head-tail source environments (for the HT sources
in our sample) display dipolar anisotropy in that higher galaxy density appears
to lie in the direction of the tails. Excluding the Head-tail and Wide-angle
tail sources, subsamples of FRI and FRII sources from the ATLBS survey appear
to lie in similar moderately overdense environments, with no evidence for
redshift evolution in the regimes studied herein.


title: Invariants of wreath products and subgroups of S_6

abstract:
  Let $G$ be a subgroup of $S_6$, the symmetric group of degree 6. For any
field $k$, $G$ acts naturally on the rational function field $k(x_1,...,x_6)$
via $k$-automorphisms defined by $\sigma\cdot x_i=x_{\sigma(i)}$ for any
$\sigma\in G$, any $1\le i\le 6$. Theorem. The fixed field $k(x_1,...,x_6)^G$
is rational (=purely transcendental) over $k$, except possibly when $G$ is
isomorphic to $PSL_2(\bm{F}_5)$, $PGL_2(\bm{F}_5)$ or $A_6$. When $G$ is
isomorphic to $PSL_2(\bm{F}_5)$ or $PGL_2(\bm{F}_5)$, then
$\bm{C}(x_1,...,x_6)^G$ is $\bm{C}$-rational and $k(x_1,...,x_6)^G$ is stably
$k$-rational for any field $k$. The invariant theory of wreath products will be
investigated also.


title:
Peculiar Velocity Decomposition, Redshift Space Distortion and Velocity
  Reconstruction in Redshift Surveys. II. Dark Matter Velocity Statistics

abstract:
  Massive spectroscopic redshift surveys open a promising window to accurately
measure peculiar velocity at cosmological distances through redshift space
distortion (RSD). In paper I of this series of work we proposed to decompose
peculiar velocity into three eigen-modes (v_\delta, v_S and v_B) in order to
facilitate the RSD modeling and peculiar velocity reconstruction. In the
current paper we measure the dark matter RSD related statistics of the velocity
eigen-modes through a set of N-body simulations, including the velocity power
spectra, correlation functions, one-point probability distribution functions,
cumulants and the damping functions describing the Finger of God effect. (1)
The power spectrum measurement shows that these velocity components have
distinctly different spatial distribution and redshift evolution. In
particular, we measure the window function \tilde{W}(k,z), which describes the
impact of nonlinear evolution on the v_\delta-density relation. We confirm that
it can induce a significant systematic error of O(10%) in RSD cosmology. We
demonstrate that \tilde{W} can be accurately described by a simple fitting
formula with one or two free parameters. (2) The correlation function
measurement shows that the correlation length is O(100), O(10) and O(1) Mpc for
v_\delta, v_S and v_B respectively. These correlation lengths determine where
we can treat the velocity fields as spatially uncorrelated. (3) The velocity
PDFs and cumulants quantify non-Gaussianities of the velocity fields. We
confirm speculation in paper I that v_\delta is largely Gaussian, nevertheless
with non-negligible non-Gaussianity, v_B is significantly non-Gaussian. We also
measure the damping functions. Despite the observed non-Gaussianities, the
damping functions and hence the FOG effect are all well approximated as
Gaussian ones at scales of interest.


title:
Thermal properties of $D_2^*(2460)$ and $D_{s2}^*(2573)$ tensor mesons
  using QCD sum rules

abstract:
  We investigate the masses and decay constants of the heavy-light
$D_2^*(2460)$ and $D_{s2}^*(2573)$ tensor mesons in the framework of thermal
QCD sum rules. Taking into account the additional operators arising at finite
temperature, we evaluate the Wilson expansion for the two-point correlation
function associated with these mesons. We observe that the values of the masses
and decay constants decrease considerably at near to the critical temperature.
The decay constants attain roughly to $25\%$ of their values in vacuum, while
the masses decrease about $39\%$ and $37\%$ in $D_2^*$ and $D_{s2}^*$ channels,
respectively.


title:
Subgroups of mapping class groups related to Heegaard splittings and
  bridge decompositions

abstract:
  Let $M=H_1\cup_S H_2$ be a Heegaard splitting of a closed orientable
3-manifold $M$ (or a bridge decomposition of a link exterior). Consider the
subgroup $\mathrm{MCG}^0(H_j)$ of the mapping class group of $H_j$ consisting
of mapping classes represented by auto-homeomorphisms of $H_j$ homotopic to the
identity, and let $G_j$ be the subgroup of the automorphism group of the curve
complex $\mathcal{CC}(S)$ obtained as the image of $\mathrm{MCG}^0(H_j)$. Then
the group $G=<G_1, G_2>$ generated by $G_1$ and $G_2$ preserve the homotopy
class in $M$ of simple loops on $S$. In this paper, we study the structure of
the group $G$ and the problem to what extent the converse to this observation
holds.


title: The Financing of Innovative SMEs: a multicriteria credit rating model

abstract:
  Small Medium-sized Enterprises (SMEs) face many obstacles when they try to
access credit market. These obstacles are increased if the SMEs are innovative.
In this case, financial data are insufficient or even not reliable. Thus, when
building a judgemental rating model, mainly based on qualitative criteria (soft
information), it is very important to finance SMEs' activities. Until now,
there isn't a multicriteria credit risk model based on soft information for
innovative SMEs. In this paper, we try to fill this gap by presenting a
multicriteria credit risk model, specifically, ELECTRE-TRI. To obtain robust
SMEs' assignments to the risk classes, a SMAA-TRI analysis is also implemented.
In fact, SMAA-TRI incorporates ELECTRE-TRI by considering different sets of
preference parameters with Monte Carlo simulations. Finally, we carry out some
real case studies, with the aim of illustrating the multicriteria credit risk
model proposed.


title:
Head Gesture Recognition using Optical Flow based Classification with
  Reinforcement of GMM based Background Subtraction

abstract:
  This paper describes a technique of real time head gesture recognition
system. The method includes Gaussian mixture model (GMM) accompanied by optical
flow algorithm which provided us the required information regarding head
movement. The proposed model can be implemented in various control system. We
are also presenting the result and implementation of both mentioned method.


title: Coleman-Weinberg Higgs

abstract:
  We discuss an extension of the standard model by fields not charged under
standard model gauge symmetry in which the electroweak symmetry breaking is
driven by the Higgs quartic coupling itself without the need for a negative
mass term in the potential. This is achieved by a scalar field S with a large
coupling to the Higgs field at the electroweak scale which is driven to very
small values at high energies by the gauge coupling of a hidden symmetry under
which S is charged. This model can remain perturbative all the way to the
Planck scale. The Higgs boson is fully SM-like in its couplings to fermions and
gauge bosons. However, the effective cubic and quartic self-couplings of the
Higgs boson are significantly enhanced.


title: Alcuin's Propositiones de Civitatibus: the Earliest Packing Problems

abstract:
  We consider three problems about cities from Alcuin's_Propositiones ad
acuendos juvenes_. These problems can be considered as the earliest packing
problems difficult also for modern state-of-the-art packing algorithms. We
discuss the Alcuin's solutions and give the known (to the author) best
solutions to these problems.


title: Sub-Piconewton Force Detection using Micron-Size Wire Deflections

abstract:
  The mechanical properties of nanostructured wires obtained by co-assembly of
iron oxide particles are studied. The intrinsic magnetic properties of the
wires are used to induce and quantify the bending of the one-dimensional
objects. From the relationship between the deflection and the magnitude of the
magnetic field, the elastic rigidity and Young modulus of the wires are
determined. Young moduli in the megapascal range are obtained and are
consistent with sub-piconewton force detection.


title:
Evidence from Tunneling Spectroscopy for a Quasi-One Dimensional Origin
  of Superconductivity in Sr2RuO4

abstract:
  To establish the mechanism of unconventional superconductivity in
Sr$_2$RUO$_4$, a prerequisite is direct information concerning the
momentum-space structure of the energy gaps $\Delta_i(k)$, and in particular
whether the pairing strength is stronger ("dominant") on the quasi-1D ($\alpha$
and $\beta$) or on the quasi-2D ($\gamma$) Fermi surfaces. We present scanning
tunneling microscopy (STM) measurements of the density-of-states spectra in the
superconducting state of Sr$_2$RuO$_4$ for $0.1 T_C<T<T_C$, and analyze them,
along with published thermodynamic data, using a simple phenomenological model.
We show that our observation of a single superconducting gap scale with maximum
value $2\Delta \approx 5 T_C$ along with a spectral shape indicative of line
nodes is consistent, within a weak-coupling model, with magnetically mediated
odd-parity superconductivity generated by dominant, near-nodal Cooper pairing
on the $\alpha$ and $\beta$ bands.


title: Generalization of isomorphism theorems groups to Partial groups

abstract:
  In this paper, we define a new structure analogous to group, called partial
group. This structure concerns the partial stability by the composition inner
law. We generalize the three isomorphism theorems for groups to partial groups.


title: Non-orientable wormholes as portals to the mirror world

abstract:
  We examine the compatibility of the mirror matter concept with the
non-orientable wormholes. If any particle (or classical object) is traversing
through the non-orientable wormhole, it turns into a corresponding mirror
particle and vice versa. The critical sonic point in the hydrodynamical flow of
the perfect fluid is located exactly at the throat of the wormhole. This means
that wormholes are traversable for the fluid. The astrophysical signatures of
the presence of non-orientable wormholes in the Universe are discussed. Some
non-trivial aspects of the non-orientable wormholes electrodynamics are
considered.


title: Context Specific Event Model For News Articles

abstract:
  We present a new context based event indexing and event ranking model for
News Articles. The context event clusters formed from the UNL Graphs uses the
modified scoring scheme for segmenting events which is followed by clustering
of events. From the context clusters obtained three models are developed-
Identification of Main and Sub events; Event Indexing and Event Ranking. Based
on the properties considered from the UNL Graphs for the modified scoring main
events and sub events associated with main-events are identified. The temporal
details obtained from the context cluster are stored using hashmap data
structure. The temporal details are place-where the event took; person-who
involved in that event; time-when the event took place. Based on the
information collected from the context clusters three indices are generated-
Time index, Person index, and Place index. This index gives complete details
about every event obtained from context clusters. A new scoring scheme is
introduced for ranking the events. The scoring scheme for event ranking gives
weight-age based on the priority level of the events. The priority level
includes the occurrence of the event in the title of the document, event
frequency, and inverse document frequency of the events.


title:
Accretion, Ablation and Propeller Evolution in Close Millisecond Pulsar
  Binary Systems

abstract:
  A model for the formation and evolution of binary millisecond radio pulsars
in systems with low mass companions (< 0.1 Msun) is investigated using a binary
population synthesis technique. Taking into account the non conservative
evolution of the system due to mass loss from an accretion disk as a result of
propeller action and from the companion via ablation by the pulsar, the
transition from the accretion powered to rotation powered phase is
investigated. It is shown that the operation of the propeller and ablation
mechanisms can be responsible for the formation and evolution of black widow
millisecond pulsar systems from the low mass X-ray binary phase at an orbital
period of ~0.1 day. For a range of population synthesis input parameters, the
results reveal that a population of black widow millisecond pulsars
characterized by orbital periods as long as ~0.4 days and companion masses as
low as ~0.005 Msun can be produced. The orbital periods and minimum companion
mass of this radio millisecond pulsar population critically depend on the
thermal bloating of the semi-degenerate hydrogen mass losing component, with
longer orbital periods for a greater degree of bloating. Provided that the
radius of the companion is increased by about a factor of 2 relative to a fully
degenerate, zero temperature configuration, an approximate agreement between
observed long orbital periods and theoretical modeling of hydrogen rich donors
can be achieved. We find no discrepancy between the estimated birth rates for
LMXBs and black widow systems, which on average are $\sim~1.3\times10^{-5} {\rm
yr}^{-1}$ and $1.3\times10^{-7} {\rm yr}^{-1}$ respectively.


title: The dependence of the ice-albedo feedback on atmospheric properties

abstract:
  The ice-albedo feedback is a potentially important de-stabilizing effect for
the climate of terrestrial planets. It is based on the positive feedback
between decreasing surface temperatures, an increase of snow and ice cover and
an associated increase in planetary albedo, which then further decreases
surface temperature. A recent study shows that for M stars, the strength of the
ice-albedo feedback is reduced
  This study investigates the influence of the atmosphere (in terms of surface
pressure and atmospheric composition) for this feedback. A plane-parallel
radiative transfer model is used for the calculation of planetary albedos. We
varied CO2 partial pressures as well as the H2O, CH4, and O3 content in the
atmosphere for planets orbiting Sun-like and M-type stars.
  Results suggest that for planets around M stars, the ice-albedo effect is
significantly reduced, compared to planets around Sun-like stars. Including the
effects of an atmosphere further suppresses the sensitivity to the ice-albedo
effect. Atmospheric key properties such as surface pressure, but also the
abundance of radiative trace gases can considerably change the strength of the
ice-albedo feedback. For dense CO2 atmospheres of the order of a few to tens of
bar, atmospheric rather than surface properties begin to dominate the planetary
radiation budget. At high CO2 pressures, the ice-albedo feedback is strongly
reduced for planets around M stars. The presence of trace amounts of H2O and
CH4 in the atmosphere also weakens the ice-albedo effect for both stellar types
considered. For planets around Sun-like stars, O3 could also lead to a very
strong decrease of the ice-albedo feedback at high CO2 pressures. (abridged)


title: Trading USDCHF filtered by Gold dynamics via HMM coupling

abstract:
  We devise a USDCHF trading strategy using the dynamics of gold as a filter.
Our strategy involves modelling both USDCHF and gold using a coupled hidden
Markov model (CHMM). The observations will be indicators, RSI and CCI, which
will be used as triggers for our trading signals. Upon decoding the model in
each iteration, we can get the next most probable state and the next most
probable observation. Hopefully by taking advantage of intermarket analysis and
the Markov property implicit in the model, trading with these most probable
values will produce profitable results.


title:
Comparison of quantum discord and relative entropy in some bipartite
  quantum systems

abstract:
  The study of quantum correlations in High-dimensional bipartite systems is
crucial for the development of quantum computing. We propose relative entropy
as a distance measure of correlations may be measured by means of the distance
from the quantum state to the closest classical-classical state. In particular,
We establish relations between relative entropy and quantum discord quantifiers
obtained by means of orthogonal projective measurements. We show that for
symmetrical X-states density matrices the quantum discord is equal to relative
entropy. At the end of paper, various examples of X-states such as two-qubit
and qubit-qutrit have been demonstrated .


title:
Spherically symmetric cosmological spacetimes with dust and radiation -
  numerical implementation

abstract:
  We present new numerical cosmological solutions of the Einstein Field
Equations. The spacetime is spherically symmetric with a source of dust and
radiation approximated as a perfect fluid. The dust and radiation are
necessarily non-comoving due to the inhomogeneity of the spacetime. Such a
model can be used to investigate non-linear general relativistic effects
present during decoupling or big-bang nucleosynthesis, as well as for
investigating void models of dark energy with isocurvature degrees of freedom.
We describe the full evolution of the spacetime as well as the redshift and
luminosity distance for a central observer. After demonstrating accuracy of the
code, we consider a few example models, and demonstrate the sensitivity of the
late time model to the degree of inhomogeneity of the initial radiation
contrast.


title: The Calabi-Yau problem, null curves, and Bryant surfaces

abstract:
  In this paper we prove that every bordered Riemann surface M admits a
complete proper null holomorphic embedding into a ball of the complex Euclidean
$3$-space $\mathbb{C}^3$. The real part of such an embedding is a complete
conformal minimal immersion $M\to \mathbb{R}^3$ with bounded image. For any
such $M$ we also construct proper null holomorphic embeddings $M\to
\mathbb{C}^3$ with a bounded coordinate function; these give rise to properly
embedded null curves $M\to SL_2(\mathbb{C})$ and to properly immersed Bryant
surfaces $M\to \mathbb{H}^3$ in the hyperbolic $3$-space. In particular, we
give the first examples of proper Bryant surfaces with finite topology and of
hyperbolic conformal type. The main novelty when compared to the existing
results in the literature is that we work with a fixed conformal structure on
$M$. This is accomplished by introducing a conceptually new method based on
complex analytic techniques. One of our main tools is an approximate solution
to the Riemann-Hilbert boundary value problem for null curves in
$\mathbb{C}^3$.


title: Microscopic analysis of the octupole phase transition in Th isotopes

abstract:
  A shape phase transition between stable octupole deformation and octupole
vibrations in Th nuclei is analyzed in a microscopic framework based on nuclear
density functional theory. The relativistic functional DD-PC1 is used to
calculate axially-symmetric quadrupole-octupole constrained energy surfaces.
Observables related to order parameters are computed using an interacting-boson
Hamiltonian, with parameters determined by mapping the microscopic energy
surfaces to the expectation value of the Hamiltonian in the boson condensate.
The systematics of constrained energy surfaces and low-energy excitation
spectra point to the occurrence of a phase transition between octupole-deformed
shapes and shapes characterized by octupole-soft potentials.


title:
Shaping the evanescent field of optical nanofibers for cold atom
  trapping

abstract:
  We investigate trapping geometries for cold, neutral atoms that can be
created in the evanescent field of a tapered optical fibre by combining the
fundamental mode with one of the next lowest possible modes, namely the HE21
mode. Counter propagating red-detuned HE21 modes are combined with a
blue-detuned HE11 fundamental mode to form a potential in the shape of four
intertwined spirals. By changing the polar- ization from circular to linear in
each of the two counter-propagating HE21 modes simultaneously the 4-helix
configuration can be transformed into a lattice configuration. The modification
to the 4-helix configuration due to unwanted excitation of the the T E01 and T
M01 modes is also discussed.


title:
Explosive reconnection of double tearing modes in relativistic plasmas:
  application to the Crab flares

abstract:
  Magnetic reconnection associated to the double tearing mode (DTM) is
investigated by means of resistive relativistic magnetohydrodynamic (RRMHD)
simulations. A linearly unstable double current sheet system in two dimensional
cartesian geometry is considered. For initial perturbations of large enough
longitudinal wavelengths, a fast reconnection event is triggered by a secondary
instability that is structurally driven by the nonlinear evolution of the
magnetic islands. The latter reconnection phase and time scale appear to weakly
depend on the plasma resistivity and magnetization parameter. We discuss the
possible role of such explosive reconnection dynamics to explain the MeV flares
observed in the Crab pulsar nebula. Indeed the time scale and the critical
minimum wavelength give constraints on the Lorentz factor of the striped wind
and on the location of the emission region respectively.


title: The complexity of resolving conflicts on MAC

abstract:
  We consider the fundamental problem of multiple stations competing to
transmit on a multiple access channel (MAC). We are given $n$ stations out of
which at most $d$ are active and intend to transmit a message to other stations
using MAC. All stations are assumed to be synchronized according to a time
clock. If $l$ stations node transmit in the same round, then the MAC provides
the feedback whether $l=0$, $l=2$ (collision occurred) or $l=1$. When $l=1$,
then a single station is indeed able to successfully transmit a message, which
is received by all other nodes. For the above problem the active stations have
to schedule their transmissions so that they can singly, transmit their
messages on MAC, based only on the feedback received from the MAC in previous
round.
  For the above problem it was shown in [Greenberg, Winograd, {\em A Lower
bound on the Time Needed in the Worst Case to Resolve Conflicts
Deterministically in Multiple Access Channels}, Journal of ACM 1985] that every
deterministic adaptive algorithm should take $\Omega(d (\lg n)/(\lg d))$ rounds
in the worst case. The fastest known deterministic adaptive algorithm requires
$O(d \lg n)$ rounds. The gap between the upper and lower bound is $O(\lg d)$
round. It is substantial for most values of $d$: When $d = $ constant and $d
\in O(n^{\epsilon})$ (for any constant $\epsilon \leq 1$, the lower bound is
respectively $O(\lg n)$ and O(n), which is trivial in both cases. Nevertheless,
the above lower bound is interesting indeed when $d \in$ poly($\lg n$). In this
work, we present a novel counting argument to prove a tight lower bound of
$\Omega(d \lg n)$ rounds for all deterministic, adaptive algorithms, closing
this long standing open question.}


title: Boundary $C^*$-algebras of triangle geometries

abstract:
  Let $\Delta$ be a building of type $\widetilde A_2$ and order $q$, with
maximal boundary $\Omega$. Let $\Gamma$ be a group of type preserving
automorphisms of $\Delta$ which acts regularly on the chambers of $\Delta$.
Then the crossed product $C^*$-algebra $C(\Omega) \rtimes \Gamma$ is isomorphic
to $M_{3(q+1)} \otimes\cl O_{q^2}\otimes\cl O_{q^2}$, where $\cl O_n$ denotes
the Cuntz algebra generated by $n$ isometries whose range projections sum to
the identity operator.


title: Rationality problem of generalized Ch\^atelet surfaces

abstract:
  The surface $z^2=ay^2+P(x), \, a \in k, \, P(x) \in k[x]$ is not
$k$-rational, if $a \not\in k^2$ and $P(x)$ satisfies some conditions. This
result essentially due to Iskovskih but his statement is in terms of algebraic
geometry, and not so easy to access for the researchers of the field extension.
This paper aims to give a formulation accessible more easily. A necessary and
sufficient condition for $k$-rationality is given in terms of $a$ and $P$,
assuming that $\ch k \not= 2$ and every irreducible component of $P(x)$ is
separable over $k$.


title:
The Tunka Radio Extension (Tunka-Rex): Status and First Results (ICRC
  2013)

abstract:
  Tunka-Rex is a new radio antenna array which extends the Tunka experiment in
Siberia close to lake Baikal. It consists of 20 antennas on an area of 1 km^2
which measure the radio emission of high-energy air showers. Tunka-Rex is
triggered by the photomultiplier array of Tunka measuring air-Cherenkov light
of air showers in the energy range from about 10 PeV to 1 EeV. This
configuration allows for the worldwide first hybrid measurements of the radio
and air-Cherenkov signal for the same events: an ideal situation to perform a
cross-calibration between both methods. Consequently, the main goal of
Tunka-Rex is to determine the achievable energy and Xmax precision of radio
measurements by comparing them to the reconstruction of the air-Cherenkov
measurements. Tunka-Rex started operation in autumn 2012, and already detected
air-shower events. In this paper we present the status of Tunka-Rex and first
results which indicate that Tunka-Rex measures indeed the radio emission by air
showers and that is is sensitive to their energy.


title:
Continuous Renormalization Group Analysis of Spectral Problems in
  Quantum Field Theory

abstract:
  The isospectral renormalization group is a powerful method to analyze the
spectrum of operators in quantum field theory. It was introduced in 1995 [see
\cite{BachFrohlichSigal1995}, \cite{BachFrohlichSigal1998}] and since then it
has been used to prove several results for non-relativistic quantum
electrodynamics. After the introduction of the method there have been many
works in which extensions, simplifications or clarifications are presented (see
\cite{BachChenFrohlichSigal2003}, \cite{GriesemerHasler2008},
\cite{FrohlichGriesemerSigal2009}). In this paper we present a new approach in
which we construct a flow of operators parametrized by a continuous variable in
the positive real axis. While this is in contrast to the discrete iteration
used before, this is more in spirit of the original formulation of the
renormalization group introduced in theoretical physics in 1974
\cite{KogutWilson1974}. The renormalization flow that we construct can be
expressed in a simple way: it can be viewed as a single application of the
Feshbach-Schur map with a clever selection of the spectral parameter. Another
advantage of the method is that there exists a flow function for which the
renormalization group that we present is the orbit under this flow of an
initial Hamiltonian. This opens the possibility to study the problem using
different techniques coming from the theory of evolution equations.


title:
Quantum frequency conversion of quantum memory compatible photons to
  telecommunication wavelengths

abstract:
  We report an experiment demonstrating quantum frequency conversion of weak
light pulses compatible with atomic quantum memories to telecommunication
wavelengths. We use a PPLN nonlinear waveguide to convert weak coherent states
at the single photon level with a duration of 30ns from a wavelength of 780nm
to 1552nm. We measure a maximal waveguide internal (external) conversion
efficiency eta_int = 0.41 (eta_ext = 0.25), and we show that the signal to
noise ratio (SNR) is good enough to reduce the input photon number below 1. In
addition, we show that the noise generated by the pump beam in the crystal is
proportional to the spectral bandwidth of the device, suggesting that narrower
filtering could significantly increase the SNR. Finally, we demonstrate that
the quantum frequency converter can operate in the quantum regime by converting
a time-bin qubit and measuring the qubit fidelity after conversion.


title: Sound velocities of hexagonal close-packed H2 and He under pressure

abstract:
  Bulk, shear, and compressional aggregate sound velocities of hydrogen and
helium in the close- packed hexagonal structure are calculated over a wide
pressure range using two complementary approaches: semi-empirical lattice
dynamics based on the many-body intermolecular potentials and
density-functional theory in the generalized gradient approximation. The sound
velocities are used to calculate pressure dependence of the Debye temperature.
The comparison between experiment and first-principle and semi-empirical
calculations provide constraints on the density dependence of intermolecular
interactions in the zero-temperature limit.


title: A general phase noise relationship for four-wave mixing

abstract:
  We propose and verify the use of the power spectral density of the FM noise
spectrum to study the phase noise relationship between the four-wave mixing
components.


title:
Critical state solution and AC loss computation of polygonally arranged
  thin superconducting tapes

abstract:
  The current density and field distributions in polygonally arranged thin
superconducting tapes carrying AC current are derived under the assumption of
the critical state model. Starting from the generic Biot-Savart law for a
general polygonal geometry, we derive a suitable integral equation for the
calculation of the current density and magnetic field in each tape. The model
works for any transport current below $I_c$, which makes it attractive for
studying cases of practical interest, particularly the dependence of AC losses
on parameters such as the number of tapes, their distance from the center, and
their separation.


title:
Convergence Rates of Distributed Nesterov-like Gradient Methods on
  Random Networks

abstract:
  We consider distributed optimization in random networks where N nodes
cooperatively minimize the sum \sum_{i=1}^N f_i(x) of their individual convex
costs. Existing literature proposes distributed gradient-like methods that are
computationally cheap and resilient to link failures, but have slow convergence
rates. In this paper, we propose accelerated distributed gradient methods that:
1) are resilient to link failures; 2) computationally cheap; and 3) improve
convergence rates over other gradient methods. We model the network by a
sequence of independent, identically distributed random matrices {W(k)} drawn
from the set of symmetric, stochastic matrices with positive diagonals. The
network is connected on average and the cost functions are convex,
differentiable, with Lipschitz continuous and bounded gradients. We design two
distributed Nesterov-like gradient methods that modify the D-NG and D-NC
methods that we proposed for static networks. We prove their convergence rates
in terms of the expected optimality gap at the cost function. Let k and K be
the number of per-node gradient evaluations and per-node communications,
respectively. Then the modified D-NG achieves rates O(log k/k) and O(\log K/K),
and the modified D-NC rates O(1/k^2) and O(1/K^{2-\xi}), where \xi>0 is
arbitrarily small. For comparison, the standard distributed gradient method
cannot do better than \Omega(1/k^{2/3}) and \Omega(1/K^{2/3}), on the same
class of cost functions (even for static networks). Simulation examples
illustrate our analytical findings.


title: The Tunka-Rex antenna station (ICRC 2013)

abstract:
  Tunka-Rex is the radio extension of Tunka-133, a 1 km^2 air-Cherenkov
Detector for air showers in Siberia. Tunka-Rex began operation on October 8th
2012 with 20 radio antennas. Its main goals are to explore the possible
precision of the radio detection technique in determination of primary energy
and mass. Each radio antenna station consists of two perpendicular aligned
active SALLA antennas, which receive the radio signal from air showers. The
preamplified radio signal is transmitted to local cluster centers of the
Tunka-133 DAQ, where it is filtered, amplified and digitized. To reconstruct
the radio signal it is crucial to understand how it is affected in each of
these steps. Thus, we have studied the combined response of the antenna, with
its directional pattern and the analog electronics chain, consisting of a
Low-Noise Amplifier and a filter amplifier. We discuss the hardware setup of
Tunka-Rex and how a description of its response is obtained. Furthermore, we
estimate systematic uncertainties on the reconstructed radio signal due to
hardware effects (e.g., slight variations of the electronics properties).
Finally, we present background measurements with the actual Tunka-Rex antennas.


title: Strong variable linear polarization in the cool active star II Peg

abstract:
  Magnetic fields of cool active stars are currently studied polarimetrically
using only circular polarization observations. Including linear polarization in
the reconstruction of stellar magnetic fields allows more information about the
magnetic field to be extracted and significantly improves the reliability of
stellar magnetic field maps. The goal of this study is to initiate systematic
observations of active stars in all four Stokes parameters and to identify cool
stars for which linear polarization can be detected at a level sufficient for
Zeeman Doppler imaging (ZDI). Four active RS CVn binaries, II Peg, HR 1099, IM
Peg, and sigma Gem, were observed with the ESPaDOnS spectropolarimeter at the
Canada-France-Hawaii Telescope during a time period from February 2012 to
January 2013. The least-squares deconvolution procedure was applied to derive
mean polarization profiles of all four Stokes parameters. Linear polarization
was detected in all four stars in at least one observation. At the same time,
II Peg showed an exceptionally strong and highly variable linear polarization
signature throughout all observations. This establishes II Peg as the first
promising target for ZDI in all four Stokes parameters and suggests the
feasibility of such an analysis with existing equipment for at least a few of
the most active cool stars.


title:
Detection of a variable QPO at ~41 mHz in the Be/X-ray transient pulsar
  4U 0115+634

abstract:
  We report the detection of quasi-periodic oscillation (QPO) at ~41 mHz in the
transient high-mass Be/X-ray binary pulsar 4U~0115+634 using data from the
Rossi X-Ray Timing Explorer (RXTE) observatory. The observations used in the
present work were carried out during X-ray outbursts in 1999 March-April, 2004
September-October and 2008 March-April. This frequency of the newly detected
QPO was found to vary in 27-46 mHz range. This ~41 mHz QPO was detected in four
of the 36 pointed RXTE Proportional Counter Array (PCA) observations during
1999 outburst where as during 2004 and 2008 outbursts, it was detected in four
and three times out of 33 and 26 observations, respectively. Though QPOs at ~2
mHz, and ~62 mHz were reported earlier, the ~41 mHz QPO and its first harmonic
were detected for the first time in this pulsar. There are three RXTE/PCA
observations where multiple QPOs were detected in the power density spectrum of
4U~0115+634. Simultaneous presence of multiple QPOs is rarely seen in accretion
powered X-ray pulsars. Spectral analysis of all the pointed RXTE/PCA
observations revealed that the 3-30 keV energy spectrum was well described by
Negative and Positive Power-law with EXponential cutoff (NPEX) continuum model
along with interstellar absorption and cyclotron absorption components. During
the three X-ray outbursts, however, no systematic variation in any of the
spectral parameters other than the earlier reported anti-correlation between
cyclotron absorption energy and luminosity was seen. Presence of any systematic
variation of QPO frequency and rms of QPO with source flux were also
investigated yielding negative results.


title: Nonlinear differential identities for cnoidal waves

abstract:
  This article presents a family of nonlinear differential identities for the
spatially periodic function $u_s(x)$, which is essentially the Jacobian
elliptic function $\cn^2(z;m(s))$ with one non-trivial parameter $s$. More
precisely, we show that this function $u_s$ fulfills equations of the form
{equation*}
\big(u_s^{(\alpha)}u_s^{(\beta)}\big)(x)=\sum_{n=0}^{2+\alpha+\beta}b_{\alpha,\beta}(n)u_s^{(n)}(x)+c_{\alpha,\beta},
{equation*} for any $s>0$ and for all $\alpha,\beta\in\N_0$. We give explicit
expressions for the coefficients $b_{\alpha,\beta}(n)$ and $c_{\alpha,\beta}$
for given $s$.
  Moreover, we show that for any $s$ satisfying $\sinh(\pi/(2s))\geq 1$ the set
of functions $\{1,u^{\vphantom{a}}_s,u'_s,u"_s,...\}$ constitutes a basis for
$L^2(0,2\pi)$. By virtue of our formulas the problem of finding a periodic
solution to any nonlinear wave equation reduces to a problem in the
coefficients. A finite ansatz exactly solves the KdV equation (giving the
well-known cnoidal wave solution) and the Kawahara equation. An infinite ansatz
is expected to be especially efficient if the equation to be solved can be
considered a perturbation of the KdV equation.


title:
Accretion through the inner edges of protoplanetary disks by a giant
  solid state pump

abstract:
  At the inner edge of a protoplanetary disk solids are illuminated by stellar
light. This illumination heats the solids and creates temperature gradients
along their surfaces. Interactions with ambient gas molecules lead to a radial
net gas flow. Every illuminated solid particle within the edge is an individual
small gas pump transporting gas inward. In total the inner edge can provide
local mass flow rates as high as $\dot{M} = 10^{-5} M_{\odot}$ yr$^{-1}$.


title:
Fermionic condensation in ultracold atoms, nuclear matter and neutron
  stars

abstract:
  We investigate the Bose-Einstein condensation of fermionic pairs in three
different superfluid systems: ultracold and dilute atomic gases, bulk neutron
matter, and neutron stars. In the case of dilute gases made of fermionic atoms
the average distance between atoms is much larger than the effective radius of
the inter-atomic potential. Here the condensation of fermionic pairs is
analyzed as a function of the s-wave scattering length, which can be tuned in
experiments by using the technique of Feshbach resonances from a small and
negative value (corresponding to the Bardeen-Cooper-Schrieffer (BCS) regime of
Cooper Fermi pairs) to a small and positive value (corresponding to the regime
of the Bose-Einstein condensate (BEC) of molecular dimers), crossing the
unitarity regime where the scattering length diverges. In the case of bulk
neutron matter the s-wave scattering length of neutron-neutron potential is
negative but fixed, and the condensate fraction of neutron-neutron pairs is
studied as a function of the total neutron density. Our results clearly show a
BCS-quasiunitary-BCS crossover by increasing the neutron density. Finally, in
the case of neutron stars, where again the neutron-neutron scattering length is
negative and fixed, we determine the condensate fraction as a function of the
distance from the center of the neutron star, finding that the maximum
condensate fraction appears in the crust of the neutron star.


title:
Spin and Orbital Contributions to Magnetically Ordered Moments in 5d
  Layered Perovskite Sr2IrO4

abstract:
  The ratio of orbital (L) and spin (S) contributions to the magnetically
ordered moments of a 5d transition metal oxide, Sr2IrO4 was evaluated by
non-resonant magnetic x-ray diffraction. We applied a new experimental setting
to minimize the error in which we varied only the linear-polarization of
incident x-ray at a fixed scattering angle. Strong polarization dependence of
the intensity of magnetic diffraction was observed, from which we conclude that
the ordered moments contain substantial contribution from the orbital degree of
freedom with the ratio of <L>/<S> ~5.0, evidencing the pronounce effect of
spin-orbit coupling. The obtained ratio is close to but slightly larger than
the expected value for the ideal J_eff = 1/2 moment of a spin-orbital Mott
insulator, |<J_1/2|L_z|J_1/2>|/|<J_1/2|S_z|J_1/2>| = 4, which cannot be
accounted by the redistribution of orbital components within the t_2g bands
associated with the elongation of the IrO6 octahedra.


title: Testing the Dipole Modulation Model in CMBR

abstract:
  The hemispherical power asymmetry, observed in the CMBR data, has generally
been interpreted in terms of the dipole modulation model for the temperature
fluctuations. Here we point out that this model leads to several predictions,
which can be directly tested in the current data. We suggest tests of the
hemispherical power asymmetry both in real and multipole space. We find a
significant signal of the dipole modulation model in WMAP and PLANCK data with
our tests. The dipole amplitude and direction also agrees, within errors, with
earlier results based on hemispherical analysis in multipole space. We also
find evidence that the effective dipole modulation amplitude increases with the
multipole l in the range l=2-64.


title:
Unveiling correlations between financial variables and topological
  metrics of trading networks: Evidence from a stock and its warrant

abstract:
  Traders adopt different trading strategies to maximize their returns in
financial markets. These trading strategies not only results in specific
topological structures in trading networks, which connect the traders with the
pairwise buy-sell relationships, but also have potential impacts on market
dynamics. Here, we present a detailed analysis on how the market behaviors are
correlated with the structures of traders in trading networks based on audit
trail data for the Baosteel stock and its warrant at the transaction level from
22 August 2005 to 23 August 2006. In our investigation, we divide each trade
day into 48 time windows with a length of five minutes, construct a trading
network within each window, and obtain a time series of over 1,100 trading
networks. We find that there are strongly simultaneous correlations between the
topological metrics (including network centralization, assortative index, and
average path length) of trading networks that characterize the patterns of
order execution and the financial variables (including return, volatility,
intertrade duration, and trading volume) for the stock and its warrant. Our
analysis may shed new lights on how the microscopic interactions between
elements within complex system affect the system's performance.


title:
Analytical results for front pinning between an hexagonal pattern and a
  uniform state in pattern-formation systems

abstract:
  In pattern-forming systems, localized patterns are states of intermediate
complexity between fully extended ordered patterns and completely irregular
patterns. They are formed by stationary fronts enclosing an ordered pattern
inside an homogeneous background. In two dimensions, the ordered pattern is
most often hexagonal and the conditions for fronts to stabilize are still
unknown. In this letter, we show how the locking of these fronts depends on
their orientation relative to the pattern. The theory rests on general
asymptotic arguments valid when the spatial scale of the front is slow compared
to that of the hexagonal pattern. Our analytical results are confirmed by
numerical simulations with the Swift-Hohenberg equation, relevant to
hydrodynamical and buckling instabilities, and a nonlinear optical cavity
model.


title:
Ab initio investigation of the exchange interactions in
  Bi$_2$Fe$_4$O$_9$: The Cairo pentagonal lattice compound

abstract:
  We present the \emph{ab initio} calculation of the electronic structure and
magnetic properties of Bi$_2$Fe$_4$O$_9$. This compound crystallizes in the
orthorhombic crystal structure with the Fe$^{3+}$ ions forming the Cairo
pentagonal lattice implying strong geometric frustration. The neutron
diffraction measurements reveal nearly orthogonal magnetic configuration, which
at first sight is rather unexpected since it does not minimize the total energy
of the pair of magnetic ions coupled by the Heisenberg exchange interaction.
Here we calculate the electronic structure and exchange integrals of Bi2Fe4O9
within the LSDA+U method. We obtain three different in-plane (J3=36 K, J4=73 K,
J5=23 K) and two interplane (J1=10 K, J2=12 K) exchange parameters. The derived
set of exchange integrals shows that the realistic description of Bi2Fe4O9
needs a more complicated model than the ideal Cairo pentagonal lattice with
only two exchange parameters in the plane. However, if one takes into account
only two largest exchange integrals, then according to the ratio x\equiv
J3/J4=0.49<\sqrt{2} (a critical parameter for the ideal Cairo pentagonal
lattice, see. Ref.~1) the ground state should be the orthogonal magnetic
configuration in agreement with experiment. The microscopic origin of different
exchange interactions is also discussed.


title:
Spin memory and spin-lattice relaxation in two-dimensional hexagonal
  crystals

abstract:
  We propose a theory of spin relaxation of electrons and holes in
two-dimensional hexagonal crystals such as atomic layers of transition metal
dichalcogenides (MoS2, WSe2, etc). We show that even in intrinsically
defectless crystals, their flexural deformations are able to generate spin
relaxation of carriers. Based on symmetry analysis, we formulate a generic
model for spin-lattice coupling between electrons and flexural deformations,
and use it to determine temperature and material-dependent spin lifetimes in
atomic crystals in ambient conditions.


title:
Extended Supersymmetries and 2+1 Dimensional Supersymmetric Chern Simons
  Theories

abstract:
  We study N=2 supersymmetric Chern-Simons Higgs models in $(2+1)$-dimensions.
As we will demonstrate, an extended supersymmetric quantum mechanics algebras
underlies the fermionic zero modes quantum system and the zero modes
corresponding to bosonic fluctuations. These two algebras, in turn, combine to
give an N=4 extended 1-dimensional supersymmetric algebra with central charge


title:
Calibrating and Controlling the Quantum Efficiency Distribution of
  Inhomogeneously Broadened Quantum Rods Using a Mirror Ball

abstract:
  We demonstrate that a simple silver coated ball lens can be used to
accurately measure the entire distribution of radiative transition rates of
quantum dot nanocrystals. This simple and cost-effective implementation of
Drexhage's method that uses nanometer-controlled optical mode density
variations near a mirror, not only allows to extract calibrated
ensemble-averaged rates, but for the first time also to quantify the full
inhomogeneous dispersion of radiative and non radiative decay rates across
thousands of nanocrystals. We apply the technique to novel ultra-stable
CdSe/CdS dot-in-rod emitters. The emitters are of large current interest due to
their improved stability and reduced blinking. We retrieve a room-temperature
ensemble average quantum efficiency of 0.87+-0.08 at a mean lifetime around 20
ns. We confirm a log-normal distribution of decay rates as often assumed in
literature and we show that the rate distribution-width, that amounts to about
30% of the mean decay rate, is strongly dependent on the local density of
optical states.


title:
Optimal Linear Shrinkage Estimator for Large Dimensional Precision
  Matrix

abstract:
  In this work we construct an optimal shrinkage estimator for the precision
matrix in high dimensions. We consider the general asymptotics when the number
of variables $p\rightarrow\infty$ and the sample size $n\rightarrow\infty$ so
that $p/n\rightarrow c\in (0, +\infty)$. The precision matrix is estimated
directly, without inverting the corresponding estimator for the covariance
matrix. The recent results from the random matrix theory allow us to find the
asymptotic deterministic equivalents of the optimal shrinkage intensities and
estimate them consistently. The resulting distribution-free estimator has
almost surely the minimum Frobenius loss. Additionally, we prove that the
Frobenius norms of the inverse and of the pseudo-inverse sample covariance
matrices tend almost surely to deterministic quantities and estimate them
consistently. At the end, a simulation is provided where the suggested
estimator is compared with the estimators for the precision matrix proposed in
the literature. The optimal shrinkage estimator shows significant improvement
and robustness even for non-normally distributed data.


title: Cyclic models of the relativistic universe: the early history

abstract:
  Within the framework of relativistic cosmology oscillating or cyclic models
of the universe were introduced by A. Friedmann in his seminal paper of 1922.
With the recognition of evolutionary cosmology in the 1930s this class of
closed models attracted considerable interest and was investigated by several
physicists and astronomers. Whereas the Friedmann-Einstein model exhibited only
a single maximum value, R. Tolman argued for an endless series of cycles. After
World War II, cyclic or pulsating models were suggested by W. Bonnor and H.
Zanstra, among others, but they remained peripheral to mainstream cosmology.
The paper reviews the development from 1922 to the 1960s, paying particular
attention to the works of Friedmann, Einstein, Tolman and Zanstra. It also
points out the role played by bouncing models in the emergence of modern
big-bang cosmology.


title: BRAVO for many-server QED systems with finite buffers

abstract:
  This paper demonstrates the occurrence of the feature called BRAVO (Balancing
Reduces Asymptotic Variance of Output) for the departure process of a
finite-buffer Markovian many-server system in the QED (Quality and
Efficiency-Driven) heavy-traffic regime. The results are based on evaluating
the limit of a formula for the asymptotic variance of death counts in finite
birth--death processes.


title:
Atomic-scale inversion of spin polarization at an
  organic-antiferromagnetic interface

abstract:
  Using first-principles calculations, we show that the magnetic properties of
a two-dimensional antiferromagnetic transition-metal surface are modified on
the atomic scale by the adsorption of small organic molecules. We consider
benzene (C6H6), cyclooctatetraene (C8H8) and a small transition metal - benzene
complex (BzV) adsorbed on a single atomic layer of Mn deposited on the W(110)
surface -- a surface which exhibits a nearly antiferromagnetic alignment of the
magnetic moments in adjacent Mn rows. Due to the spin-dependent hybridization
of the molecular pz orbitals with the d states of the Mn monolayer there is a
significant reduction of the magnetic moments in the Mn film. Furthermore, the
spin-polarization at this organic-antiferromagnetic interface is found to be
modulated on the atomic scale, both enhanced and inverted, as a result of the
molecular adsorption. We show that this effect can be resolved by
spin-polarized scanning tunneling microscopy (SP-STM). Our simulated SP-STM
images display a spatially-dependent spin-resolved vacuum charge density above
an adsorbed molecule -- i.e., different regions above the molecule sustain
different signs of spin polarization. While states with s and p symmetry
dominate the vacuum charge density in the vicinity of the Fermi energy for the
clean magnetic surface, we demonstrate that after a molecule is adsorbed those
d-states, which are normally suppressed due to their symmetry, can play a
crucial role in the vacuum due to their interaction with the molecular
orbitals. We also model the effect of small deviations from perfect
antiferromagnetic ordering, induced by the slight canting of magnetic moments
due to the spin spiral ground state of Mn/W(110).


title: On some negative motivic homology groups

abstract:
  For an arbitrary separated scheme $X$ of finite type over a finite field
$\mathbb F_q$ and an integer $j=-1,-2,$ we prove under the assumption of
resolution of singularities, that the two groups $H_{-1}(X,\mathbb Z(j))$ and
$H_{-1}(\pi_0(X),\mathbb Z(j))$ are canonically isomorphic. This gives an
explicit computation of $H_{-1}(X,\mathbb Z(j)).$


title: Omitting parentheses from the cyclic notation

abstract:
  The purpose of this article is to initiate a combinatorial study of the
Bruhat-Chevalley ordering on certain sets of permutations obtained by omitting
the parentheses from their standard cyclic notation. In particular, we show
that these sets form a bounded, graded, unimodal, rank-symmetric and
EL-shellable posets. Moreover, we determine the homotopy types of the
associated order complexes.


title: Optimum Size of Nanorods for Heating Application

abstract:
  Magnetic nanoparticles (MNP's) have become increasingly important in heating
applications such as hyperthermia treatment of cancer due to their ability to
release heat when a remote external alternating magnetic field is applied. It
has been shown that the heating capability of such particles varies
significantly with the size of particles used. In this paper, we theoretically
evaluate the heating capability of rod-shaped MNP's and identify conditions
under which these particles display highest efficiency. For optimally sized
monodisperse particles, the power generated by rod-shaped particles is found to
be equal to that generated by spherical particles. However, for particles which
have a dispersion in size, rod-shaped particles are found to be more effective
in heating as a result of the greater spread in the power density distribution
curve. Additionally, for rod-shaped particles, a dispersion in the radius of
the particle contributes more to the reduction in loss power when compared to a
dispersion in the length. We further identify the optimum size, i.e the radius
and length of nanorods, given a bi-variate log-normal distribution of particle
size in two dimensions.


title: Handling Parallelism in a Concurrency Model

abstract:
  Programming models for concurrency are optimized for dealing with
nondeterminism, for example to handle asynchronously arriving events. To shield
the developer from data race errors effectively, such models may prevent shared
access to data altogether. However, this restriction also makes them unsuitable
for applications that require data parallelism. We present a library-based
approach for permitting parallel access to arrays while preserving the safety
guarantees of the original model. When applied to SCOOP, an object-oriented
concurrency model, the approach exhibits a negligible performance overhead
compared to ordinary threaded implementations of two parallel benchmark
programs.


title:
BEC-BCS Crossover in Neutron Matter with Renormalization Group based
  Effective Interactions

abstract:
  We study pure neutron matter in the BEC-BCS crossover regime using
renormalization group based low-momentum interactions within the
Nozi\`eres-Schmitt-Rink framework. This is an attempt to go beyond the mean
field description for low-density matter. We work in the basis of so-called
Weinberg eigenvectors where the operator $G_0V$ is diagonal, which proves to be
an excellent choice that allows one to use non-local interactions in a very
convenient way. We study the importance of correlations as a function of
density. We notice that there is a significant reduction of the BCS critical
temperature at low-densities as the neutron matter approaches the unitary
limit.


title:
Energetics of marine turbine arrays - extraction, dissipation and
  diminution

abstract:
  A two-scale modelling approach is discussed to predict the performance and
energetics of a large number (more than a few hundred) of marine turbines
installed as a power farm in a general coastal environment. The kernel of this
approach is that the outer, or coastal-scale, model/simulation is to assess the
reduction of flow passing through a given farm area as a function of the
increase of head loss across the farm, whereas the inner, or device-scale,
model/simulation employs this function to account for the (otherwise unknown)
effect of coastal dynamics for that farm site, i.e. diminution of the power
removed from the farm area due to the reduction of flow through the farm.
Large-eddy simulations (LES) of periodic open channel flow (with a porous plate
model representing turbines) are then presented as a device-scale part of such
a two-scale model of large marine turbine arrays. Results demonstrate the
usefulness of this approach to study how the overall energetics of turbine
arrays (i.e. extraction, dissipation and diminution of energy within the entire
farm area) may change depending on the characteristics of the farm site, array
configuration and operating conditions of the turbines in the farm.


title: Room temperature water Leidenfrost droplets

abstract:
  We experimentally investigate the Leidenfrost effect at pressures ranging
from 1 to 0.05 atmospheric pressure. As a direct consequence of the
Clausius-Clapeyron phase diagram of water, the droplet temperature can be at
ambient temperature in a non-sophisticated lab environment. Furthermore, the
lifetime of the Leidenfrost droplet is significantly increased in this low
pressure environment. The temperature and pressure dependance of the
evaporation rate are successfully tested against a recently proposed model.
These results may pave a way to reach efficient Leidenfrost micro-fluidic and
milli-fluidic applications.


title: Relative inner amenability

abstract:
  Let $G$ be a subgroup of a discrete (countable) group $\Gamma$. We introduce
a notion of relative inner amenability of $G$ in $\Gamma$, we prove some
equivalent conditions and provide examples as well as counter-examples. We also
discuss briefly the corresponding relative property gamma for pairs of finite
factors and we deduce from this a characterization of discrete, icc groups
which do not have Kazhdan's property $T$.


title: Graded Betti numbers of powers of ideals

abstract:
  Using the concept of vector partition functions, we investigate the
asymptotic behavior of graded Betti numbers of powers of homogeneous ideals in
a polynomial ring over a field. Our main results state that if the polynomial
ring is equipped with a positive $\ZZ$-grading, then the Betti numbers of
powers of ideals are encoded by finitely many polynomials.
  More precisely, in the case of $\ZZ$-grading, $\ZZ^2$ can be splitted into a
finite number of regions such that each region corresponds to a polynomial that
depending to the degree $(\mu, t)$, $\dim_k \left(\tor_i^S(I^t, k)_{\mu}
\right)$ is equal to one of these polynomials in $(\mu, t)$. This refines, in a
graded situation, the result of Kodiyalam on Betti numbers of powers of ideals.
  Our main statement treats the case of a power products of homogeneous ideals
in a $\ZZ^d$-graded algebra, for a positive grading.


title:
Binary Pulsar J0737-3039: Evidence for a new core collapse and neutron
  star formation mechanism

abstract:
  The binary pulsar J0737-3039 is the only known system having two observable
pulsars, thus offering a unique laboratory to test general relativity and
explore pulsar physics. Based on the low eccentricity and the position within
the galactic plane, Piran & Shaviv (2004, 2005) argued that pulsar B had a
non-standard formation scenario with little or no mass ejection. They have also
predicted that the system would have a very slow proper motion. Pulsar timing
measurements (Kramer et al. 2006; Deller et al. 2009) confirmed this
prediction. The recent observations of the alignment between the spin of pulsar
A and the binary orbit is also in agreement with this scenario. Detailed
simulations of the formation process of pulsar B enable us to show that its
progenitor, just before the collapse, was a massive O-Ne-Mg white dwarf
surrounded by a tenuous, 0.1-0.16 M_sun, envelope. This envelope was ejected
when the white dwarf collapsed to form a neutron star. Pulsar B was born as a
slow rotator (spin period ~ 1 s) and a kick received when the pulsar formed
changed its spin direction to the current one. This realization sheds light on
the angular momentum evolution of the progenitor star, a process which is
strongly affected by interaction with the binary companion. The slow proper
motion of the system also implies that the system must have undergone a phase
of mass transfer in which Star A shed a significant fraction of its mass onto
B.


title:
A transdimensional Bayesian method to infer the star formation history
  of resolved stellar populations

abstract:
  We propose a new method to infer the star formation histories of resolved
stellar populations. With photometry one may plot observed stars on a
colour-magnitude diagram (CMD) and then compare with synthetic CMDs
representing different star formation histories. This has been accomplished
hitherto by parametrising the model star formation history as a histogram,
usually with the bin widths set by fixed increases in the logarithm of time. A
best fit is then found with maximum likelihood methods and we consider the
different means by which a likelihood can be calculated. We then apply Bayesian
methods by parametrising the star formation history as an unknown number of
Gaussian bursts with unknown parameters. This parametrisation automatically
provides a smooth function of time. A Reversal Jump Markov Chain Monte Carlo
method is then used to find both the most appropriate number of Gaussians, thus
avoiding avoid overfitting, and the posterior probability distribution of the
star formation rate. We apply our method to artificial populations and to
observed data. We discuss the other advantages of the method: direct comparison
of different parametrisations and the ability to calculate the probability that
a given star is from a given Gaussian. This allows the investigation of
possible sub-populations.


title:
Quantum probability rule: a generalisation of the theorems of Gleason
  and Busch

abstract:
  Busch's theorem deriving the standard quantum probability rule can be
regarded as a more general form of Gleason's theorem. Here we show that a
further generalisation is possible by reducing the number of quantum postulates
used by Busch. We do not assume that the positive measurement outcome operators
are effects or that they form a probability operator measure. We derive a more
general probability rule from which the standard rule can be obtained from the
normal laws of probability when there is no measurement outcome information
available, without the need for further quantum postulates. Our general
probability rule has prediction-retrodiction symmetry and we show how it may be
applied in quantum communications and in retrodictive quantum theory.


title: A theory of baryon resonances at large N_c

abstract:
  At large number of colors, N_c quarks in baryons are in a mean field of
definite space and flavor symmetry. We write down the general Lorentz and
flavor structure of the mean field, and derive the Dirac equation for quarks in
that field. The resulting baryon resonances exhibit an hierarchy of scales: The
crude mass is O(N_c), the intrinsic quark excitations are O(1), and each
intrinsic quark state entails a finite band of collective excitations that are
split as O(1/N_c). We build a (new) theory of those collective excitations,
where full dynamics is represented by only a few constants. In a limiting (but
unrealistic) case when the mean field is spherically-and flavor-symmetric, our
classification of resonances reduces to the SU(6) classification of the old
non-relativistic quark model. Although in the real world N_c is only three, we
obtain a good accordance with the observed resonance spectrum up to 2 GeV.


title:
On the $\pi$$\mathfrak{F}$-norm and the
  $\mathfrak{H}$-$\mathfrak{F}$-norm of a finite group

abstract:
  Let $\mathfrak{H}$ be a Fitting class and $\mathfrak{F}$ a formation. We call
a subgroup $\mathcal{N}_{\mathfrak{H},\mathfrak{F}}(G)$ of a finite group $G$
the $\mathfrak{H}$-$\mathfrak{F}$-norm of $G$ if
$\mathcal{N}_{\mathfrak{H},\mathfrak{F}}(G)$ is the intersection of the
normalizers of the products of the $\mathfrak{F}$-residuals of all subgroups of
$G$ and the $\mathfrak{H}$-radical of $G$. Let $\pi$ denote a set of primes and
let $\mathfrak{G}_\pi$ denote the class of all finite $\pi$-groups. We call the
subgroup $\mathcal{N}_{\mathfrak{G}_\pi,\mathfrak{F}}(G)$ of $G$ the
$\pi\mathfrak{F}$-norm of $G$. A normal subgroup $N$ of $G$ is called
$\pi\mathfrak{F}$-hypercentral in $G$ if either $N=1$ or $N>1$ and every
$G$-chief factor below $N$ of order divisible by at least one prime in $\pi$ is
$\mathfrak{F}$-central in $G$. Let $Z_{\pi\mathfrak{F}}(G)$ denote the
$\pi\mathfrak{F}$-hypercentre of $G$, that is, the product of all
$\pi\mathfrak{F}$-hypercentral normal subgroups of $G$. In this paper, we study
the properties of the $\mathfrak{H}$-$\mathfrak{F}$-norm, especially of the
$\pi\mathfrak{F}$-norm of a finite group $G$. In particular, we investigate the
relationship between the $\pi'\mathfrak{F}$-norm and the
$\pi\mathfrak{F}$-hypercentre of $G$.


title: K-theory, LQEL manifolds and Severi varieties

abstract:
  We use topological K-theory to study non-singular varieties with quadratic
entry locus. We thus obtain a new proof of Russo's Divisibility Property for
locally quadratic entry locus manifolds. In particular we obtain a K-theoretic
proof of Zak's theorem that the dimension of a Severi variety must be 2, 4, 8
or 16 and so resolve a conjecture of Atiyah and Berndt. We also show how the
same methods applied to dual varieties recover the Landman parity theorem.


title:
Radiative damping and emission signatures of strong superluminal waves
  in pulsar winds

abstract:
  We analyse the damping by radiation reaction and by Compton drag of strong,
superluminal electromagnetic waves in the context of pulsar winds. The
associated radiation signature is found by estimating the efficiency and the
characteristic radiation frequencies. Applying these estimates to the gamma-ray
binary containing PSR B1259-63, we show that the GeV flare observed by
Fermi-LAT can be understood as inverse Compton emission by particles scattering
photons from the companion star, if the pulsar wind termination shock acquires
a precursor of superluminal waves roughly 30 days after periastron. This
constrains the mass-loading factor of the wind $\mu=L/\dot{N}mc^2$ (where $L$
is the luminosity and $\dot{N}$ the rate of loss of electrons and positrons) to
be roughly $6\times 10^4$.


title: Detection prospects of singlet fermionic dark matter

abstract:
  A singlet fermion which interacts only with a new singlet scalar provides a
viable and minimal scenario that can explain the dark matter. The singlet
fermion is the dark matter particle whereas the new scalar mixes with the Higgs
boson providing a link between the dark matter sector and the Standard Model.
In this paper, we present an updated analysis of this model focused on its
detection prospects. Both, the parity-conserving case and the most general case
are considered. First, the full parameter space of the model is analyzed, and
the regions compatible with the dark matter constraint are obtained and
characterized. Then, the implications of current and future direct detection
experiments are taken into account. Specifically, we determine the regions of
the multidimensional parameter space that are currently excluded and those that
are going to be probed by next generation experiments. Finally, indirect
detection prospects are discussed and the expected signal at neutrino
telescopes is calculated.


title:
Global geometric difference between separable and Positive partial
  transpose states

abstract:
  In the convex set of all $3\ot 3$ states with positive partial transposes, we
show that one can take two extreme points whose convex combinations belong to
the interior of the convex set. Their convex combinations may be even in the
interior of the convex set of all separable states. In general, we need at
least $mn$ extreme points to get an interior point by their convex combination,
for the case of the convex set of all $m\ot n$ separable states. This shows a
sharp distinction between PPT states and separable states. We also consider the
same questions for positive maps and decomposable maps.


title: Toroidal Response in Dielectric Metamaterials

abstract:
  We present and analyze a dielectric cluster based on subwavelength LiTaO3
polaritonic cylinders for demonstrating toroidal response in THz regime due to
mutual coupling of Mie- resonance modes of the cylinders. Based on this
cluster, we demonstrate a low-loss metamaterial with the dominant toroidal
response, which plays a key role in achieving resonant total transmission.


title:
Lattice point counting and height bounds over number fields and
  quaternion algebras

abstract:
  An important problem in analytic and geometric combinatorics is estimating
the number of lattice points in a compact convex set in a Euclidean space. Such
estimates have numerous applications throughout mathematics. In this note, we
exhibit applications of a particular estimate of this sort to several counting
problems in number theory: counting integral points and units of bounded height
over number fields, counting points of bounded height over positive definite
quaternion algebras, and counting points of bounded height with a fixed support
over global function fields. Our arguments use a collection of height
comparison inequalities for heights over a number field and over a quaternion
algebra. We also show how these inequalities can be used to obtain existence
results for points of bounded height over a quaternion algebra, which
constitute non-commutative analogues of variations of the classical Siegel's
lemma and Cassels' theorem on small zeros of quadratic forms.


title: On Klein's Icosahedral Solution of the Quintic

abstract:
  We present an exposition of the icosahedral solution of the quintic equation
first described in Klein's classic work "Lectures on the icosahedron and the
solution of equations of the fifth degree". Although we are heavily influenced
by Klein we follow a slightly different approach which enables us to arrive at
the solution more directly.


title:
Ks- and Lp-band polarimetry on stellar and bow-shock sources in the
  Galactic center

abstract:
  Infrared observations of the Galactic center (GC) provide a unique
opportunity to study stellar and bow-shock polarization effects in a dusty
environment. The goals of this work are to present new Ks- and Lp-band
polarimetry on an unprecedented number of sources in the central parsec of the
GC, thereby expanding our previous results in the H- and Ks-bands. We use
AO-assisted Ks- and Lp-band observations, obtained at the ESO VLT. High
precision photometry and the new polarimetric calibration method for NACO allow
us to map the polarization in a region of 8" x 25" (Ks) resp. 26" x 28" (Lp).
These are the first polarimetric observations of the GC in the Lp-band in 30
years, with vastly improved spatial resolution compared to previous results.
This allows resolved polarimetry on bright bow-shock sources in this area for
the first time at this wavelength. We find foreground polarization to be
largely parallel to the Galactic plane (Ks-band: 6.1% at 20 degrees, Lp-band:
4.5% at 20 degrees, in good agreement with our previous findings and with older
results. The previously described Lp-band excess in the foregound polarization
towards the GC could be confirmed here for a much larger number of sources. The
bow-shock sources contained in the FOV seem to show a different relation
between the polarization in the observed wavelength bands than what was
determined for the foreground. This points to the different relevant
polarization mechanisms. The resolved polarization patterns of IRS 5 and 10W
match the findings we presented earlier for IRS~1W. Additionally, intrinsic
Lp-band polarization was measured for IRS 1W and 21, as well as for other, less
prominent MIR-excess sources (IRS 2S, 2L, 5NE). The new data offer support for
the presumed bow-shock nature of several of these sources (1W, 5, 5NE, 10W, 21)
and for the model of bow-shock polarization presented in our last work.


title: Multiple Half-Quantum Vortices in Rotating Superfluid $^3$He

abstract:
  Half-quantum votices and ordinary vortices in a rotating thin film superfluid
$^3$He under a strong magnetic field are considered. It is shown that $2n+1$
half-quantum vortices interpolates between $n$ singular vortices and $n+1$
singular vortices as the angular velocity is changed. The phase diagram of the
vortex configurations in the angular velocity-magnetic field space is obtained
for a paramagnon parameter $\delta=0.05$.


title: The Skin In The Game Heuristic for Protection Against Tail Events

abstract:
  Standard economic theory makes an allowance for the agency problem, but not
the compounding of moral hazard in the presence of informational opacity,
particularly in what concerns high-impact events in fat tailed domains (under
slow convergence for the law of large numbers). Nor did it look at exposure as
a filter that removes nefarious risk takers from the system so they stop
harming others. \textcolor{red}{ (In the language of probability, skin in the
game creates an absorbing state for the agent, not just the principal)}. But
the ancients did; so did many aspects of moral philosophy. We propose a global
and morally mandatory heuristic that anyone involved in an action which can
possibly generate harm for others, even probabilistically, should be required
to be exposed to some damage, regardless of context. While perhaps not
sufficient, the heuristic is certainly necessary hence mandatory. It is
supposed to counter voluntary and involuntary risk hiding$-$ and risk transfer
$-$ in the tails. We link the rule to various philosophical approaches to
ethics and moral luck.


title:
LORD: Leader-based framework for Resource Discovery in Mobile Device
  Clouds

abstract:
  We provide a novel solution for Resource Discovery (RD) in mobile device
clouds consisting of selfish nodes. Mobile device clouds (MDCs) refer to
cooperative arrangement of communication-capable devices formed with
resource-sharing goal in mind. Our work is motivated by the observation that
with ever-growing applications of MDCs, it is essential to quickly locate
resources offered in such clouds, where the resources could be content,
computing resources, or communication resources. The current approaches for RD
can be categorized into two models: decentralized model, where RD is handled by
each node individually; and centralized model, where RD is assisted by
centralized entities like cellular network. However, we propose LORD, a
Leader-based framewOrk for RD in MDCs which is not only self-organized and not
prone to having a single point of failure like the centralized model, but also
is able to balance the energy consumption among MDC participants better than
the decentralized model. Moreover, we provide a credit-based incentive to
motivate participation of selfish nodes in the leader selection process, and
present the first energy-aware leader selection mechanism for credit-based
models. The simulation results demonstrate that LORD balances energy
consumption among nodes and prolongs overall network lifetime compared to
decentralized model.


title:
Bottomonium states versus recent experimental observations in the
  QCD-inspired potential model

abstract:
  In the QCD-inspired potential model where the quark-antiquark interaction
consists of the usual one-gluon-exchange and the mixture of long-range scalar
and vector linear confining potentials with the lowest order relativistic
correction, we investigate the mass spectra and electromagnetic processes of a
bottomonium system by using the Gaussian expansion method. It reveals that the
vector component of the mixing confinement is anticonfining and takes around
18.51% of the confining potential. Combining the new experimental data released
by Belle, BaBar and LHC, we systematically discuss the energy levels of the
bottomonium states and make the predictions of the electromagnetic decays for
further experiments.


title:
First evidence for the two-body charmless baryonic decay $B^0 \to p
  \bar{p}$

abstract:
  The results of a search for the rare two-body charmless baryonic decays $B^0
\to p \bar{p}$ and $B_s^0 \to p \bar{p}$ are reported. The analysis uses a data
sample, corresponding to an integrated luminosity of 0.9 fb$^{-1}$, of $pp$
collision data collected by the LHCb experiment at a centre-of-mass energy of 7
TeV. An excess of $B^0 \to p \bar{p}$ candidates with respect to background
expectations is seen with a statistical significance of 3.3 standard
deviations. This is the first evidence for a two-body charmless baryonic $B^0$
decay. No significant $B_s^0 \to p \bar{p}$ signal is observed, leading to an
improvement of three orders of magnitude over previous bounds. If the excess
events are interpreted as signal, the 68.3% confidence level intervals on the
branching fractions are {eqnarray} \cal{B}(B^0 \to p \bar{p}) & = & (1.47
\,^{+0.62}_{-0.51} \,^{+0.35}_{-0.14}) \times 10^{-8} \,, *{0.3cm}
\cal{B}(B_s^0 \to p \bar{p}) & = & (2.84 \,^{+2.03}_{-1.68} \,^{+0.85}_{-0.18})
\times 10^{-8} \,, {eqnarray} where the first uncertainty is statistical and
the second is systematic.


title:
Effect of drift, selection and recombination on the equilibrium
  frequency of deleterious mutations

abstract:
  We study the stationary state of a population evolving under the action of
random genetic drift, selection and recombination in which both deleterious and
reverse beneficial mutations can occur. We find that the equilibrium fraction
of deleterious mutations decreases as the population size is increased. We
calculate exactly the steady state frequency in a nonrecombining population
when population size is infinite and for a neutral finite population, and
obtain bounds on the fraction of deleterious mutations. We also find that for
small and very large populations, the number of deleterious mutations depends
weakly on recombination, but for moderately large populations, recombination
alleviates the effect of deleterious mutations. An analytical argument shows
that recombination decreases disadvantageous mutations appreciably when
beneficial mutations are rare as is the case in adapting microbial populations,
whereas it has a moderate effect on codon bias where the mutation rates between
the preferred and unpreferred codons are comparable.


title:
Closure and commutability results for Gamma-limits and the geometric
  linearization and homogenization of multi-well energy functionals

abstract:
  Under a suitable notion of equivalence of integral densities we prove a
$\Gamma$-closure theorem for integral functionals: The limit of a sequence of
$\Gamma$-convergent families of such functionals is again a $\Gamma$-convergent
family. Its $\Gamma$-limit is the limit of the $\Gamma$-limits of the original
problems. This result not only provides a common basic principle for a number
of linearization and homogenization results in elasticity theory. It also
allows for new applications as we exemplify by proving that geometric
linearization and homogenization of multi-well energy functionals commute.


title: Diverging fluctuations in a spatial five-species cyclic dominance game

abstract:
  A five-species predator-prey model is studied on a square lattice where each
species has two prey and two predators on the analogy to the
Rock-Paper-Scissors-Lizard-Spock game. The evolution of the spatial
distribution of species is governed by site exchange and invasion between the
neighboring predator-prey pairs, where the cyclic symmetry can be characterized
by two different invasion rates. The mean-field analysis has indicated periodic
oscillations in the species densities with a frequency becoming zero for a
specific ratio of invasion rates. When varying the ratio of invasion rates, the
appearance of this zero-eigenvalue mode is accompanied by neutrality between
the species associations. Monte Carlo simulations of the spatial system reveal
diverging fluctuations at a specific invasion rate, which can be related to the
vanishing dominance between all pairs of species associations.


title: Magnonic momentum transfer force on domain walls confined in space

abstract:
  Momentum transfer from incoming magnons to a Bloch domain wall is calculated
using one dimensional continuum micromagnetic analysis. Due to the confinement
of the wall in space, the dispersion relation of magnons is different from that
of a single domain. This mismatch of dispersion relations can result in
reflection of magnons upon incidence on the domain wall, whose direct
consequence is a transfer of momentum between magnons and the domain wall. The
corresponding counteraction force exerted on the wall can be used for the
control of domain wall motion through magnonic linear momentum transfer, in
analogy with the spin transfer torque induced by magnonic angular momentum
transfer.


title:
Bateman method for two-body scattering without partial-wave
  decomposition

abstract:
  The use of Bateman method for solving the two-variable version of the
Lippmann-Schwinger equation without recourse to partial-wave decomposition is
investigated. Bateman method is based on a special kind of interpolation of the
momentum representation of the potential on a multi-variate grid. A suitable
scheme for the generation of a multi-variate Cartesian grid is described. The
method is tested in the nucleon-nucleon scattering employing a model
two-nucleon potential. Our results show that the Bateman method is capable of
producing quite accurate solutions with relatively small number of grid points.


title: Hetero-epitaxial EuO Interfaces Studied by Analytic Electron Microscopy

abstract:
  With nearly complete spin polarization, the ferromagnetic semiconductor
europium monoxide could enable next-generation spintronic devices by providing
efficient ohmic spin injection into silicon. Spin injection is greatly affected
by the quality of the interface between the injector and silicon. Here, we use
atomic-resolution scanning transmission electron microscopy in conjunction with
electron energy loss spectroscopy to directly image and chemically characterize
a series of EuO|Si and EuO|YAlO3 interfaces fabricated using different growth
conditions. We identify the presence of europium silicides and regions of
disorder at the EuO|Si interfaces, imperfections that could significantly
reduce spin injection efficiencies via spin-flip scattering.


title:
Recombination Amplitude Calculations of Noble Gases, in Length and
  Acceleration Forms, beyond Strong Field Approximation

abstract:
  Transition of an electron from a free to a bound state is critical in
determining the qualitative shape of the spectrum in high-order harmonic
generation (HHG), and in tomographic imaging of orbitals. We calculate and
compare the recombination amplitude, from a continuum state described by a
plane wave and an outgoing scattering eigenstate, to the bound state for the
noble gases that are commonly used in HHG. These calculations are based on the
single active electron model and the Hartree-Fock-Slater method, using both the
length form and the acceleration form of the dipole matrix element. We confirm
that the recombination amplitude versus emitted photon energy strongly depends
upon the wavefunction used to describe the free electron. Depending on the
choice of the wavefunction and the dipole form, the square of the absolute
value of the recombination amplitude can differ by almost two orders of
magnitude near the experimentally measured Cooper minima. Moreover, only the
outgoing scattering eigenstates with the length form roughly predict the
experimentally observed Cooper minimum for Ar (~50 eV) and Kr (~85 eV). We
provide a detailed derivation of the photorecombination cross sections (PRCSs)
from photo ionization cross sections (PICSs) calculated by the relativistic
random phase approximation (RRPA)., For Ar, Kr and Xe, compare the total PICSs
calculated using our recombination amplitudes with that obtained from RRPA. We
find that PICS calculated using the outgoing scattering eigenstates with the
length form is in better agreement with the RRPA calculations than the
acceleration form.


title: First principles study of pentacene on Au(111)

abstract:
  We investigate the atomic and electronic structure of a single layer of
pentacene on the Au(111) surface using density functional theory. To find the
candidate structures we strain match the pentacene crystal geometry with the
Au(111) surface, in this way we find pentacene overlayer structures with a low
strain. We show that the geometries obtained with this approach has lower
energy than previous proposed surface geometries of pentacene on Au(111). We
also show that the geometry and workfunction of the obtained structures are in
excellent agreement with experimental data.


title: Weighing the Local Group in the Presence of Dark Energy

abstract:
  We revise the mass estimate of the Local Group (LG) when Dark Energy (in the
form of the Cosmological Constant) is incorporated into the Timing Argument
(TA) mass estimator for the Local Group (LG). Assuming the age of the Universe
and the Cosmological Constant according to the recent values from the Planck
CMB experiment, we find the mass of the LG to be M_TAL = (4.73 +- 1.03) x
10^{12} M_sun, which is 13% higher than the classical TA mass estimate. This
partly explains the discrepancy between earlier results from LCDM simulations
and the classical TA. When a similar analysis is performed on 16 LG-like galaxy
pairs from the CLUES simulations, we find that the scatter in the ratio of the
virial to the TA estimated mass is given by M_vir/M_TAL = 1.04 +-0.16. Applying
it to the LG mass estimation we find a calibrated M_vir = (4.92 +- 1.08 (obs)
+- 0.79 (sys)) x 10^{12} M_sun.


title: Clustering and Community Detection in Directed Networks: A Survey

abstract:
  Networks (or graphs) appear as dominant structures in diverse domains,
including sociology, biology, neuroscience and computer science. In most of the
aforementioned cases graphs are directed - in the sense that there is
directionality on the edges, making the semantics of the edges non symmetric.
An interesting feature that real networks present is the clustering or
community structure property, under which the graph topology is organized into
modules commonly called communities or clusters. The essence here is that nodes
of the same community are highly similar while on the contrary, nodes across
communities present low similarity. Revealing the underlying community
structure of directed complex networks has become a crucial and
interdisciplinary topic with a plethora of applications. Therefore, naturally
there is a recent wealth of research production in the area of mining directed
graphs - with clustering being the primary method and tool for community
detection and evaluation. The goal of this paper is to offer an in-depth review
of the methods presented so far for clustering directed networks along with the
relevant necessary methodological background and also related applications. The
survey commences by offering a concise review of the fundamental concepts and
methodological base on which graph clustering algorithms capitalize on. Then we
present the relevant work along two orthogonal classifications. The first one
is mostly concerned with the methodological principles of the clustering
algorithms, while the second one approaches the methods from the viewpoint
regarding the properties of a good cluster in a directed network. Further, we
present methods and metrics for evaluating graph clustering results,
demonstrate interesting application domains and provide promising future
research directions.

categories: cs.SI cs.IR physics.bio-ph physics.comp-ph physics.soc-ph


title: Large Scale Molecular Dynamics Simulations of Homogeneous Nucleation

abstract:
  We present results from large-scale molecular dynamics (MD) simulations of
homogeneous vapor-to-liquid nucleation. The simulations contain between one and
eight billion Lennard-Jones (LJ) atoms, covering up to 1.2 {\mu}s (56 million
time-steps). They cover a wide range of supersaturation ratios, S=1.55 to 10^4,
and temperatures from kT = 0.3 to 1.0 {\epsilon} (where {\epsilon} is the depth
of the LJ potential, and k the Boltzmann constant). We have resolved nucleation
rates as low as 10^{17} cm^{-3} s^{-1} (in the argon system), and critical
cluster sizes as large as 100 atoms. Recent argon nucleation experiments probe
nucleation rates in an overlapping range, making the first direct comparison
between laboratory experiments and molecular dynamics simulations possible: We
find very good agreement within the uncertainties, which are mainly due to the
extrapolations of argon and LJ saturation curves to very low temperatures. The
self-consistent, modified classical nucleation model of Girshick and Chiu [J.
Chem. Phys. 93, 1273 (1990)] underestimates the nucleation rates by up to 9
orders of magnitudes at low temperatures, and at kT = 1.0 {\epsilon} it
overestimates them by up to 10^5. The predictions from a semi-phenomenological
model by Laaksonen et al. [Phys. Rev. E 49, 5517 (1994)] are much closer to our
MD results, but still differ by factors of up to 104 in some cases. At low
temperatures, the classical theory predicts critical clusters sizes, which
match the simulation results (using the first nucleation theorem) quite well,
while the semi-phenomenological model slightly underestimates them. At kT = 1.0
{\epsilon} the critical sizes from both models are clearly too small.
(abridged)

categories: physics.chem-ph cond-mat.mes-hall cond-mat.soft cond-mat.stat-mech physics.comp-ph