title:
Short-Term Variability of X-rays from Accreting Neutron Star Vela X-1:
  I. Suzaku Observations

abstract:
  We have analyzed the time variability of the wide-band X-ray spectrum of Vela
X-1, the brightest wind-fed accreting neutron star, on a short timescale of 2
ks by using {\it Suzaku} observations with an exposure of 100 ks. During the
observation, the object showed strong variability including several flares and
so-called "low states", in which the X-ray luminosity decreases by an order of
magnitude. Although the spectral hardness increases with the X-ray luminosity,
the majority of the recorded flares do not show any significant changes of
circumstellar absorption. However, a sign of heavy absorption was registered
immediately before one short flare that showed a significant spectral
hardening. In the low states, the flux level is modulated with the pulsar spin
period, indicating that even at this state the accretion flow reaches the close
proximity of the neutron star. Phenomenologically, the broad-band X-ray
spectra, which are integrated over the entire spin phase, are well represented
by the "NPEX" function (a combination of negative and positive power laws with
an exponential cutoff by a common folding energy) with a cyclotron resonance
scattering feature at 50 keV. Fitting of the data allowed us to infer a
correlation between the photon index and X-ray luminosity. Finally, the
circumstellar absorption shows a gradual increase in the orbital phase interval
0.25--0.3, which can be interpreted as an impact of a bow shock imposed by the
motion of the compact object in the supersonic stellar wind.


title: A sneaky proof of the maximum modulus principle

abstract:
  A proof for the maximum modulus principle (in the unit disc) is presented.
This proof is unusual in that it is based on linear algebra.


title:
Nodal curves and components of the Hilbert scheme of curves in $\mathbb
  {P}^r$ with the expected number of moduli

abstract:
  We study the existence of components with the expected number of moduli of
the Hilbert scheme of integral nodal curves $C \subset \mathbb {P}^r$ with
prescribed degree, arithmetic genus and number of singular points.


title:
Tuning the phase sensitivity of a double-lambda system with a static
  magnetic field

abstract:
  We study the effect of a DC magnetic field on the phase sensitivity of a
double-lambda system coupled by two laser fields, a probe and a pump. It is
demonstrated that the gain and the refractive index of the probe can be
controlled by either the magnetic field or the relative phase between the two
laser fields. More interestingly, when the system reduces to a single-lambda
system, turning on the magnetic field transforms the system from a
phase-insensitive process to a phase-sensitive one. In the pulsed-probe regime,
we observed switching between slow and fast light when the magnetic field or
the relative phase was adjusted. Experiments using a coated 87Rb vapor cell
produced results in good agreement with our numerical simulation. This work
provides a novel and simple means to manipulate phase sensitive
electromagnetically-induced-transparency or four-wave mixing, and could be
useful for applications in quantum optics, nonlinear optics and magnetometery
based on such systems.


title: Distribution of logarithmic spectra of the equilibrium energy

abstract:
  Let $L$ be a big invertible sheaf on a complex projective variety, equipped
with two continuous metrics. We prove that the distribution of the eigenvalues
of the transition matrix between the $L^2$ norms on $H^0(X,nL)$ with respect to
the two metriques converges (in law) as $n$ goes to infinity to a Borel
probability measure on $\mathbb R$. This result can be thought of as a
generalization of the existence of the energy at the equilibrium as a limit, or
an extension of Berndtsson's results to the more general context of graded
linear series and a more general class of line bundles. Our approach also
enables us to obtain a $p$-adic analogue of our main result.


title: Doping Dependence of the Plasmon Dispersion in 2H-Tantalum-Diselenide

abstract:
  Inelastic electron scattering is applied to investigate the impact of
potassium intercalation on the charge carrier plasmon energy and dispersion in
the charge-density wave (CDW) bearing compound 2H-tantalum-diselenide. We
observe an unususal doping dependence of the plasmon dispersion, which even
changes sign upon alkali addition. In contrast to the continous energy shift of
the plasmon position upon doping at lowest momentum transfer, its dispersion
changes in a rather discontinuous manner. We argue that the observed dynamics
can only be explained in a picture, where complex phenomena are taken into
account including the suppression of the CDW upon doping as well as the
interplay of the CDW and the plasma resonance.


title: Hidden symmetry and Collective behavior

abstract:
  We study the relationship between the partially synchronous state and the
coupling structure in general dynamical systems. Our results show that, on the
contrary to the widely accepted concept, topological symmetry in a coupling
structure is the sufficient condition but not the necessary condition.
Furthermore, we find the necessary and sufficient condition for the existence
of the partial synchronization and develop a method to obtain all of the
existing partially synchronous solutions for all nonspecific dynamics from a
very large number of possible candidates.


title:
Reproducing the $Z_c(3900)$ structure through the
  initial-single-pion-emission mechanism

abstract:
  Being stimulated by the recent BESIII observation of a charged charmoniumlike
structure $Z_c(3900)$, in this work we study the distributions of the
$J/\psi\pi^\pm$ and $\pi^+\pi^-$ invariant mass spectra of the $Y(4260)\to
\pi^+\pi^- J/\psi$ decay by the initial-single-pion-emission mechanism, where
the interference effects of the ISPE mechanism with two other decay modes are
also taken into account. The obtained $d\Gamma(Y(4260)\to \pi^+\pi^-
J/\psi)/dm_{J/\psi \pi^\pm}$ and $d\Gamma(Y(4260)\to \pi^+\pi^-
J/\psi)/dm_{\pi^+ \pi^-}$ marvelously agree with the BESIII data to reproduce
the $Z_c(3900)$ structure.


title:
A hybrid scheme for encoding audio signal using hidden Markov models of
  waveforms

abstract:
  This paper reports on recent results related to audiophonic signals encoding
using time-scale and time-frequency transform. More precisely, non-linear,
structured approximations for tonal and transient components using local cosine
and wavelet bases will be described, yielding expansions of audio signals in
the form tonal + transient + residual. We describe a general formulation
involving hidden Markov models, together with corresponding rate estimates.
Estimators for the balance transient/tonal are also discussed.


title:
A polynomial representation and a unique code of a simple undirected
  graph

abstract:
  In this note we introduce a representation of simple undirected graphs in
terms of polynomials and obtain a unique code for a simple undirected graph.


title:
The time-evolution of DCIS size distributions with applications to
  breast cancer growth and progression

abstract:
  Ductal carcinoma {\em in situ} (DCIS) lesions are non-invasive tumours of the
breast which are thought to precede most invasive breast cancers (IBC). As
individual DCIS lesions are initiated, grow and invade (i.e. become IBC) the
size distribution of the DCIS lesions present in a given human population will
evolve. We derive a differential equation governing this evolution and show,
for given assumptions about growth and invasion, that there is a unique
distribution which does not vary with time. Further, we show that any initial
distribution converges to this stationary distribution exponentially quickly.
It is therefore reasonable to assume that the stationary distribution is equal
to the true DCIS size distribution, at least for human populations which are
relatively stable with respect to the determinants of breast cancer. Based on
this assumption and the size data of 110 DCIS lesions detected in a
mammographic screening program between 1993 and 2000, we produce maximum
likelihood estimates for certain growth and invasion parameters. Assuming that
DCIS size is proportional to a positive power $p$ of the time since tumour
initiation we estimate $p$ to be 0.50 with a 95% confidence interval of $(0.35,
0.71)$. Therefore we estimate that DCIS lesions follow a square-root growth law
and hence that they grow rapidly when small and relatively slowly when large.
Our approach and results should be useful for other mathematical studies of
cancer, especially those investigating biological mechanisms of invasion.


title: Chain minors are FPT

abstract:
  Given two finite posets P and Q, P is a chain minor of Q if there exists a
partial function f from the elements of Q to the elements of P such that for
every chain in P there is a chain C_Q in Q with the property that f restricted
to C_Q is an isomorphism of chains. We give an algorithm to decide whether a
poset P is a chain minor of o poset Q that runs in time O(|Q| log |Q|) for
every fixed poset P. This solves an open problem from the monograph by Downey
and Fellows [Parameterized Complexity, 1999] who asked whether the problem was
fixed parameter tractable.


title:
Large System Analysis of Linear Precoding in MISO Broadcast Channels
  with Confidential Messages

abstract:
  In this paper, we study the performance of regularized channel inversion
(RCI) precoding in large MISO broadcast channels with confidential messages
(BCC). We obtain a deterministic approximation for the achievable secrecy
sum-rate which is almost surely exact as the number of transmit antennas $M$
and the number of users $K$ grow to infinity in a fixed ratio $\beta=K/M$. We
derive the optimal regularization parameter $\xi$ and the optimal network load
$\beta$ that maximize the per-antenna secrecy sum-rate. We then propose a
linear precoder based on RCI and power reduction (RCI-PR) that significantly
increases the high-SNR secrecy sum-rate for $1<\beta<2$. Our proposed precoder
achieves a per-user secrecy rate which has the same high-SNR scaling factor as
both the following upper bounds: (i) the rate of the optimum RCI precoder
without secrecy requirements, and (ii) the secrecy capacity of a single-user
system without interference. Furthermore, we obtain a deterministic
approximation for the secrecy sum-rate achievable by RCI precoding in the
presence of channel state information (CSI) error. We also analyze the
performance of our proposed RCI-PR precoder with CSI error, and we determine
how the error must scale with the SNR in order to maintain a given rate gap to
the case with perfect CSI.


title: Ancilla Assisted Quantum State Tomography in Many-Qubit Registers

abstract:
  The standard method of Quantum State Tomography (QST) relies on the
measurement of a set of noncommuting observables, realized in a series of
independent experiments. Ancilla Assisted QST (AAQST) proposed by Nieuwenhuizen
and co-workers (Phys. Rev. Lett., 92, 120402 (2004)) greatly reduces the number
of independent measurements by exploiting an ancilla register in a known
initial state. In suitable conditions AAQST allows mapping out density matrix
of an input register in a single experiment. Here we describe methods for
explicit construction of AAQST experiments in multi-qubit registers. We also
report nuclear magnetic resonance studies on AAQST of (i) a two- qubit input
register using a one-qubit ancilla in an isotropic liquid-state system and (ii)
a three-qubit input register using a two-qubit ancilla register in a partially
oriented system. The experimental results confirm the effectiveness of AAQST in
such many-qubit registers.


title: The unusual afterglow of the Gamma-Ray Burst 100621A

abstract:
  In order to constrain the broad-band spectral energy distribution of the
afterglow of GRB 100621A, dedicated observations were performed in the
optical/near-infrared with the 7-channel "Gamma-Ray Burst Optical and
Near-infrared Detector" (GROND) at the 2.2m MPG/ESO telescope, in the
sub-millimeter band with the large bolometer array LABOCA at APEX, and at radio
frequencies with ATCA. Utilizing also Swift X-ray observations, we attempt an
interpretation of the observational data within the fireball scenario.
  The afterglow of GRB 100621A shows a very complex temporal as well as
spectral evolution. We identify three different emission components, the most
spectacular one causing a sudden intensity jump about one hour after the prompt
emission. The spectrum of this component is much steeper than the canonical
afterglow. We interpret this component using the prescription of Vlasis et al.
(2011) for a two-shell collision after the first shell has been decelerated by
the circumburst medium. We use the fireball scenario to derive constraints on
the microphysical parameters of the first shell. Long-term energy injection
into a narrow jet seems to provide an adequate description. Another noteworthy
result is the large ($A_V$ = 3.6 mag) line-of-sight host extinction of the
afterglow in an otherwise extremely blue host galaxy.


title: Direct Imaging in the Habitable Zone and the Problem of Orbital Motion

abstract:
  High contrast imaging searches for exoplanets have been conducted on 2.4-10 m
telescopes, typically at H band (1.6 microns) and used exposure times of ~1 hr
to search for planets with semi-major axes of > ~10 AU. We are beginning to
plan for surveys using extreme-AO systems on the next generation of 30-meter
class telescopes, where we hope to begin probing the habitable zones (HZs) of
nearby stars. Here we highlight a heretofore ignorable problem in direct
imaging: planets orbit their stars. Under the parameters of current surveys,
orbital motion is negligible over the duration of a typical observation.
However, this motion is not negligible when using large diameter telescopes to
observe at relatively close stellar distances (1-10pc), over the long exposure
times (10-20 hrs) necessary for direct detection of older planets in the HZ. We
show that this motion will limit our achievable signal-to-noise ratio and
degrade observational completeness. Even on current 8m class telescopes,
orbital motion will need to be accounted for in an attempt to detect HZ planets
around the nearest sun-like stars alpha Cen A & B, a binary system now known to
harbor at least one planet. Here we derive some basic tools for analyzing this
problem, and ultimately show that the prospects are good for de-orbiting a
series of shorter exposures to correct for orbital motion.


title: Coexistence of p-wave Cooper pairing and ferromagnetism

abstract:
  A two-band model for coexistence of p-wave superconductivity with localized
ferromagnetism is studied using the equation of motion approach. It shows that
ferromagnetic and superconducting states enhance each other but in a different
way from that of the one-band model. The Curie temperature is not only
determined by the exchange interactions between localized spins, but also can
be increased with the coupling between electrons and spins, and with the p-wave
Cooper-pairing interaction. These results are complementary to those of the
one-band model, which suggest that the Curie temperature is unlikely to ever be
below the superconducting transition temperature.


title:
Entropy scaling from chaotically produced particles in p-p collisions at
  LHC energies

abstract:
  Scaling of information entropy obtained from chaotically produced particles
in p-p collisions, has been shown to be valid up to the highest available
collision energy at LHC. Results from Monte Carlo simulation model PYTHIA 6.135
have also been compared. Based on the two com- ponent model and collision
energy dependence of the chaoticity, charged particle multiplicities at
proposed higher collision energies have been predicted.


title: Fundamental Limits of Distributed Caching in D2D Wireless Networks

abstract:
  We consider a wireless Device-to-Device (D2D) network where communication is
restricted to be single-hop, users make arbitrary requests from a finite
library of possible files and user devices cache information in the form of
linear combinations of packets from the files in the library (coded caching).
We consider the combined effect of coding in the caching and delivery phases,
achieving "coded multicast gain", and of spatial reuse due to local short-range
D2D communication. Somewhat counterintuitively, we show that the coded
multicast gain and the spatial reuse gain do not cumulate, in terms of the
throughput scaling laws. In particular, the spatial reuse gain shown in our
previous work on uncoded random caching and the coded multicast gain shown in
this paper yield the same scaling laws behavior, but no further scaling law
gain can be achieved by using both coded caching and D2D spatial reuse.


title: Quasistatic Stick-slip in Dislocation Core and Frenkel-Kontorova Chain

abstract:
  By means of atomistic simulations, we demonstrate that a dislocation core
exhibits intermittent quasistatic restructuring during incremental shear within
the same Peierls valley. This can be regarded as a stick-slip transition, which
is also reproduced for a one-dimensional Frenkel-Kontorova chain under rigid
boundary conditions. This occurs due to a discontinuous jump in an order
parameter of the system, which signifies the extent of region forbidden for the
presence of particles in the chain. The stick-slip phenomenon observed in the
dislocation core is also shown to be reflected after dimensionality reduction
of the multidimensional atomic coordinates, which provides a basis for
comparison with the simple one-dimensional chain.


title:
A Time Dependent Local Isospin Density Approximation Study of Asymmetric
  Nuclear Matter

abstract:
  The dynamic response of asymmetric nuclear matter is studied by using a
Time-Dependent Local Isospin Density (TDLIDA) approximation approach.
Calculations are based on a local density energy functional derived by an
Auxiliary Field Diffusion Monte Carlo (AFDMC) calculation of bulk nuclear
matter. Three types of excited states emerge: collective states, a continuum of
quasi-particle-quasi-hole excitations and unstable solutions. These states are
analyzed and discussed for different values of the nuclear density $\rho$ and
isospin asymmetry $\xi=(N-Z)/A$. An analytical expression of the
compressibility as a function of $\rho$ and $\xi$ is derived which show
explicitly an instability of the neutron matter around $\rho\simeq 0.09
fm^{-3}$ when a small fraction of protons is added to the system.


title: On a class of integrable systems with a quartic first integral

abstract:
  We generalize, to some extent, the results on integrable geodesic flows on
two dimensional manifolds with a quartic first integral in the framework laid
down by Selivanova and Hadeler. The local structure is first determined by a
direct integration of the differential system which expresses the conservation
of the quartic observable and is seen to involve a finite number of parameters.
The global structure is studied in some details and leads to a class of models
living on the manifolds S^2, H^2 or R^2. As special cases we recover
Kovalevskaya's integrable system and a generalization of it due to Goryachev.


title:
Effects of Zn substitution on the electronic structure of BaFe$_2$As$_2$
  revealed by angle-resolved photoemission spectroscopy

abstract:
  In Fe-based superconductors, electron doping is often realized by the
substitution of transition-metal atoms for Fe. In order to investigate how the
electronic structure of the parent compound is influenced by Zn substitution,
which supplies nominally four extra electrons per substituted atom but is
expected to induce the strongest impurity potential among the transition-metal
atoms, we have performed an angle-resolved photoemission spectroscopy
measurements on Ba(Fe_{1-x}Zn_x)_2As_2 (Zn-122). In Zn-122, the temperature
dependence of the resistivity shows a kink around T~135 K, indicating
antiferromagnetic order below the Neel temperature of T_N ~ 135 K. In fact,
folded Fermi surfaces (FSs) similar to those of the parent compound have been
observed below T_N. The hole and electron FS volumes are, therefore, different
from those expected from the rigid-band model. The results can be understood if
all the extra electrons occupy the Zn 3d state ~10 eV below the Fermi level and
do not participate in the formation of the FSs.


title: Helicoidal minimal surfaces of prescribed genus, I

abstract:
  For every genus g, we prove that S^2 x R contains complete, properly
embedded, genus-g minimal surfaces whose two ends are asymptotic to helicoids
of any prescribed pitch. We also show that as the radius of the S^2 tends to
infinity, these examples converge smoothly to complete, properly embedded
minimal surfaces in Euclidean 3-space R^3 that are helicoidal at infinity. In a
companion paper, we prove that helicoidal surfaces in R^3 of every prescribed
genus occur as such limits of examples in S^2 x R.


title: Multi-Label Classifier Chains for Bird Sound

abstract:
  Bird sound data collected with unattended microphones for automatic surveys,
or mobile devices for citizen science, typically contain multiple
simultaneously vocalizing birds of different species. However, few works have
considered the multi-label structure in birdsong. We propose to use an ensemble
of classifier chains combined with a histogram-of-segments representation for
multi-label classification of birdsong. The proposed method is compared with
binary relevance and three multi-instance multi-label learning (MIML)
algorithms from prior work (which focus more on structure in the sound, and
less on structure in the label sets). Experiments are conducted on two
real-world birdsong datasets, and show that the proposed method usually
outperforms binary relevance (using the same features and base-classifier), and
is better in some cases and worse in others compared to the MIML algorithms.


title:
Commonsense Reasoning and Large Network Analysis: A Computational Study
  of ConceptNet 4

abstract:
  In this report a computational study of ConceptNet 4 is performed using tools
from the field of network analysis. Part I describes the process of extracting
the data from the SQL database that is available online, as well as how the
closure of the input among the assertions in the English language is computed.
This part also performs a validation of the input as well as checks for the
consistency of the entire database. Part II investigates the structural
properties of ConceptNet 4. Different graphs are induced from the knowledge
base by fixing different parameters. The degrees and the degree distributions
are examined, the number and sizes of connected components, the transitivity
and clustering coefficient, the cores, information related to shortest paths in
the graphs, and cliques. Part III investigates non-overlapping, as well as
overlapping communities that are found in ConceptNet 4. Finally, Part IV
describes an investigation on rules.


title:
Persistent non-metallic behavior in Sr2IrO4 and Sr3Ir2O7 at high
  pressures

abstract:
  Iridium-based 5d transition-metal oxides are attractive candidates for the
study of correlated electronic states due to the interplay of enhanced
crystal-field, Coulomb and spin-orbit interaction energies. At ambient
pressure, these conditions promote a novel Jeff = 1/2 Mott insulating state,
characterized by a gap of the order of ~0.1 eV. We present high-pressure
electrical resistivity measurements of single crystals of Sr2IrO4 and Sr3Ir2O7.
While no indications of a pressure-induced metallic state up to 55 GPa were
found in Sr2IrO4, a strong decrease of the gap energy and of the resistance of
Sr3Ir2O7 between ambient pressure and 104 GPa confirm that this compound is in
the proximity of a metal-insulator transition.


title:
The effects of rotation on the main-sequence turnoff of intermediate-age
  massive star clusters

abstract:
  The double or extended main-sequence turnoffs (MSTOs) in the color-magnitude
diagram (CMD) of intermediate-age massive star clusters in the Large Magellanic
Cloud are generally interpreted as age spreads of a few hundred Myr. However,
such age spreads do not exist in younger clusters (i.e., 40-300 Myr), which
challenges this interpretation. The effects of rotation on the MSTOs of star
clusters have been studied in previous works, but the results obtained are
conflicting. Compared with previous works, we consider the effects of rotation
on the MS lifetime of stars. Our calculations show that rotating models have a
fainter and redder MSTO with respect to non-rotating counterparts with ages
between about 0.8 and 2.2 Gyr, but have a brighter and bluer MSTO when age is
larger than 2.4 Gyr. The spread of the MSTO caused by a typical rotation rate
is equivalent to the effect of an age spread of about 200 Myr. Rotation could
lead to the double or extended MSTOs in the CMD of the star clusters with ages
between about 0.8 and 2.2 Gyr. However, the extension is not significant; and
it does not even exist in younger clusters. If the efficiency of the mixing
were high enough, the effects of the mixing would counteract the effect of the
centrifugal support in the late stage of evolution; and the rotationally
induced extension would disappear in the old intermediate-age star clusters;
but younger clusters would have an extended MSTO. Moreover, the effects of
rotation might aid in understanding the formation of some "multiple
populations" in globular clusters.


title:
Dunkl-Type Operators with Projection Terms Associated to Orthogonal
  Subsystems in Root System

abstract:
  In this paper, we introduce a new differential-difference operator $T_\xi$
$(\xi \in \mathbb{R}^N)$ by using projections associated to orthogonal
subsystems in root systems. Similarly to Dunkl theory, we show that these
operators commute and we construct an intertwining operator between $T_\xi$ and
the directional derivative $\partial_\xi$. In the case of one variable, we
prove that the Kummer functions are eigenfunctions of this operator.


title: Equivariant cycles and cancellation for motivic cohomology

abstract:
  We introduce a Bredon motivic cohomology theory for smooth schemes defined
over a field and equipped with an action by a finite group. These cohomology
groups are defined for finite dimensional representations as the
hypercohomology of complexes of equivariant correspondences in the equivariant
Nisnevich topology. We generalize the theory of presheaves with transfers to
the equivariant setting and prove a Cancellation Theorem.


title: Functional calculus on Venturi for Groups with Finite Propagation Speed

abstract:
  Let ${\cal{M}}$ be a complete Riemannian manifold with Ricci curvature
bounded below and Laplace operator $\Delta$. The paper develops a functional
calculus for the cosine family $\cos(t\sqrt {\Delta})$ which is associated with
waves that travel at unit speed. If $f$ is holomorphic on a Venturi shaped
region, and $z^kf(z)$ is bounded for some positive integer $k$, then $f({\sqrt
\Delta})$ defines a bounded linear operator on $L^p({\cal{M}})$ for some $p>2$.
For Jacobi hypergroups with invariant measure $m$ the generalized Fourier
transform of $f\in L^1(m)$ gives $\hat f\in H^\infty (\Sigma_\omega)$ for some
strip $\Sigma_\omega$. Hence one defines $\hat f(A)$ for operators $A$ in some
Banach space that have a $H^\infty (\Sigma_\omega)$ functional calculus. The
paper introduces an operational calculus for the Mehler--Fock transform of
order zero. By transference methods, one defines $\hat f(A)$ when $\hat f$ is a
$s$-Marcinkiewicz multiplier and $e^{itA}$ is a strongly continuous operator
group on a $L^p$ space for $| 1/2-1/p| <1/s$.\par


title:
Exploring Tracer Study Service in Career Center Web Site of Indonesia
  Higher Education

abstract:
  Quality competence of worker the present do not meet labor market criteria
and the low level of labor productivity, the lack of communication between the
labor market with education, changing of socio-economic structure and global
political influence labor market, the development of science and technology
very rapidly lead to fundamental changes in terms of qualifications,
competencies and requirements for entering the workforce. Tracer Study results
can be used by universities to determine the success of the educational process
that has been done towards their students. Therefore, universities need a
technology services to support the optimization of the use of tracer study. One
of that is the use of a website to facilitate the conduct tracer study. Most
services tracer study provides information to college, like year graduated, got
a job waiting period, the first salary to work, first job, the relevance of the
curriculum to the work, and compliance with the major areas of work taken in
college. Tracer study feature in Career Center Website affect the popularity
website especially in traffic and rich file website.


title:
Parameterized Complexity of the Anchored k-Core Problem for Directed
  Graphs

abstract:
  Bhawalkar, Kleinberg, Lewi, Roughgarden, and Sharma [ICALP 2012] introduced
the Anchored k-Core problem, where the task is for a given graph G and integers
b, k, and p to find an induced subgraph H with at least p vertices (the core)
such that all but at most b vertices (called anchors) of H are of degree at
least k. In this paper, we extend the notion of k-core to directed graphs and
provide a number of new algorithmic and complexity results for the directed
version of the problem. We show that
  - The decision version of the problem is NP-complete for every k>=1 even if
the input graph is restricted to be a planar directed acyclic graph of maximum
degree at most k+2.
  - The problem is fixed parameter tractable (FPT) parameterized by the size of
the core p for k=1, and W[1]-hard for k>=2.
  - When the maximum degree of the graph is at most \Delta, the problem is FPT
parameterized by p+\Delta if k>= \Delta/2.


title:
An expression for the Mott cross section of electrons and positrons on
  nuclei with Z up t0 118

abstract:
  In the present work, an improved numerical solution for determining the
ratio,$\mathcal{R}^{\rm Mott}$, of the unscreened Mott differential cross
section (MDCS) with respect to Rutherford's formula is proposed for the
scattering of electrons and positrons on nuclei with $1\leq Z \leq 118$. It
accounts for incoming lepton energies between 1\,keV and 900\,MeV. For both
electrons and positrons, a fitting formula and a set of fitting coefficients
for the ratio $\mathcal{R}^{\rm Mott}$ on nuclei are also presented. The found
average error of the latter practical interpolated expression is typically
lower than 1% also at low energy for electrons and lower than 0.05% for
positrons for all nuclei over the entire energy range.


title: Sliding Bloom Filters

abstract:
  A Bloom filter is a method for reducing the space (memory) required for
representing a set by allowing a small error probability. In this paper we
consider a \emph{Sliding Bloom Filter}: a data structure that, given a stream
of elements, supports membership queries of the set of the last $n$ elements (a
sliding window), while allowing a small error probability. We formally define
the data structure and its relevant parameters and analyze the time and memory
requirements needed to achieve them. We give a low space construction that runs
in O(1) time per update with high probability (that is, for all sequences with
high probability all operations take constant time) and provide an almost
matching lower bound on the space that shows that our construction has the best
possible space consumption up to an additive lower order term.


title: Dimensional fragility of the Kardar-Parisi-Zhang universality class

abstract:
  We assess the dependence on substrate dimensionality of the asymptotic
scaling behavior of a whole family of equations that feature the basic
symmetries of the Kardar-Parisi-Zhang (KPZ) equation. Even for cases in which,
as expected from universality arguments, these models display KPZ values for
the critical exponents and limit distributions, their behavior deviates from
KPZ scaling for increasing system dimensions. Such a fragility of KPZ
universality contradicts naive expectations, and questions straightforward
application of universality principles for the continuum description of
experimental systems.

categories: cond-mat.stat-mech cond-mat.mtrl-sci nlin.PS physics.comp-ph


title: Single photon reflection and transmission in optomechanical system

abstract:
  Cavity Optomechanical system is speedily approaching the regime where the
radiation pressure of a single photon displaces the moving mirror. In this
paper, we consider a cavity optomechanical system where the cavity field is
driven by an external field. In the limit of weak mirror-cavity couplings, we
calculate analytically the reflection and transmission rates for cavity field
and discuss the effects of mirror-cavity coupling on the reflection and
transmission.


title: Yule-generated trees constrained by node imbalance

abstract:
  The Yule process generates a class of binary trees which is fundamental to
population genetic models and other applications in evolutionary biology. In
this paper, we introduce a family of sub-classes of ranked trees, called
Omega-trees, which are characterized by imbalance of internal nodes. The degree
of imbalance is defined by an integer 0 <= w. For caterpillars, the extreme
case of unbalanced trees, w = 0. Under models of neutral evolution, for
instance the Yule model, trees with small w are unlikely to occur by chance.
Indeed, imbalance can be a signature of permanent selection pressure, such as
observable in the genealogies of certain pathogens. From a mathematical point
of view it is interesting to observe that the space of Omega-trees maintains
several statistical invariants although it is drastically reduced in size
compared to the space of unconstrained Yule trees. Using generating functions,
we study here some basic combinatorial properties of Omega-trees. We focus on
the distribution of the number of subtrees with two leaves. We show that
expectation and variance of this distribution match those for unconstrained
trees already for very small values of w.


title:
Solving the minimum sum coloring problem via binary quadratic
  programming

abstract:
  In recent years, binary quadratic programming (BQP) has been successively
applied to solve several combinatorial optimization problems. We consider in
this paper a study of using the BQP model to solve the minimum sum coloring
problem (MSCP). For this purpose, we recast the MSCP with a quadratic model
which is then solved via a recently proposed Path Relinking (PR) algorithm
designed for the general BQP. Based on a set of MSCP benchmark instances, we
investigate the performance of this solution approach compared with existing
methods.


title:
Polarization profiles for selected microlensing events towards the
  galactic bulge

abstract:
  Gravitational microlensing, in case of relevant finite source size effects,
provides an unique tool for the study of stellar atmospheres through the
enhancement of a characteristic polarization signal. Here, we consider a set of
highly magnified events and show that for different types of source stars (as
hot, late type main sequence and cool giants) showing that the polarization
strength may be of $\simeq 0.04$ percent for late type stars and up to a few
percent for cool giants.


title: Visual Room-Awareness for Humanoid Robot Self-Localization

abstract:
  Humanoid robots without internal sensors such as a compass tend to lose their
orientation after a fall. Furthermore, re-initialisation is often ambiguous due
to symmetric man-made environments. The room-awareness module proposed here is
inspired by the results of psychological experiments and improves existing
self-localization strategies by mapping and matching the visual background with
colour histograms. The matching algorithm uses a particle-filter to generate
hypotheses of the viewing directions independent of the self-localization
algorithm and generates confidence values for various possible poses. The
robot's behaviour controller uses those confidence values to control
self-localization algorithm to converge to the most likely pose and prevents
the algorithm from getting stuck in local minima. Experiments with a symmetric
Standard Platform League RoboCup playing field with a simulated and a real
humanoid NAO robot show the significant improvement of the system.


title: Electromelting of Confined Monolayer Ice

abstract:
  In sharp contrast to the prevailing view that electric fields promote water
freezing, here we show by molecular dynamics simulations that monolayer ice
confined between two parallel plates can melt into liquid water under
perpendicularly applied electric field. The melting temperature of the
monolayer ice decreases with the increasing strength of the external field due
to field-induced disruption of the water-wall interaction induced well-ordered
network of hydrogen bond. This electromelting process should add an important
new ingredient to the physics of water.


title: Dealing with natural language interfaces in a geolocation context

abstract:
  In the geolocation field where high-level programs and low-level devices
coexist, it is often difficult to find a friendly user inter- face to configure
all the parameters. The challenge addressed in this paper is to propose
intuitive and simple, thus natural lan- guage interfaces to interact with
low-level devices. Such inter- faces contain natural language processing and
fuzzy represen- tations of words that facilitate the elicitation of
business-level objectives in our context.


title: Determining Local Transientness of Audio Signals

abstract:
  We describe a new method for estimating the degree of "transientness" and
"tonality" of a class of compound signals involving simultaneously transient
and harmonic features. The key assumption is that both transient and tonal
layers admit sparse expansions, respectively in wavelet and local cosine bases.
The estimation is performed using particular form of entropy (or theoretical
dimension) functions. We provide theoretical estimates on the behavior of the
proposed estimators, as well as numerical simulations. Audio signal coding
provides a natural field of application.


title:
$W^{1,p}_{X}$ interior estimates for variational hypoelliptic operator
  with $VMO_X$ coefficients

abstract:
  We consider a divergence form hypoelliptic operator consisting of a system of
real smooth vector fields $X_{1},..., X_{q}$ satisfying H\"ormander condition
in some domain $\Omega\subseteq\erren$. Interior $L^{p}$ estimates, $2\leq
p<\infty$, can be obtained for weak solutions of the equation
$X_j^T(a^{ij}X_iu)=X_j^T F^j,$ by assuming that the coefficients $a^{ij}$
belong locally to the space $VMO_X$ with respect to the Carnot--Caratheodory
metric induced by the vector fields.


title:
Constant residual electrostatic electron plasma mode in Vlasov-Ampere
  system

abstract:
  In a collisionless Vlasov-Poisson (V-P) electron plasma system, two types of
modes for electric field perturbation exist: the exponentially Landau damped
electron plasma waves and the initial-value sensitive ballistic modes. Here,
the V-P system is modified slightly to a Vlasov-Ampere (V-A) system. A new
constant residual mode is revealed. Mathematically, this mode comes from the
Laplace transform of an initial electric field perturbation, and physically
represents that an initial perturbation (e.g., external electric field
perturbation) would not be damped away. Thus, this residual mode is more
difficult to be damped than the ballistic mode. [Physics of Plasmas 20, 112108
(2013); doi: 10.1063/1.4831761]


title:
The Kelvin-Helmholtz Instability at CME-Boundaries in the Solar Corona:
  Observations and 2.5D MHD Simulations

abstract:
  The Atmospheric Imaging Assembly onboard the Solar Dynamics Observatory
observed a coronal mass ejection with an embedded filament on 2011 February 24,
reavealing quasi-periodic vortex-like structures at the northern side of the
filament boundary with a wavelength of approximately 14.4 Mm and a propagation
speed of about 310 +- 20 km/s. These structures could result from the
Kelvin-Helmholtz instability occurring on the boundary. We perform 2.5D
numerical simulations of the Kelvin-Helmholtz instability and compare the
simulated characteristic properties of the instability with the observations,
where we obtain qualitative as well as quantitative accordance. We study the
absence of Kelvin-Helmholtz vortex-like structures on the southern side of the
filament boundary and find that a magnetic field component parallel to the
boundary with a strength of about 20% of the total magnetic field has
stabilizing effects resulting in an asymmetric development of the instability.


title: A Full-Matrix Approach for Solving General Plasma Dispersion Relation

abstract:
  A hitherto difficult and unsolved issue in plasma physics is how to give a
general numerical solver for complicated plasma dispersion relation, although
we have long known the general analytical forms. We transform the task to a
full-matrix eigenvalue problem, which allows to numerically calculate all the
dispersion relation solutions exactly free from convergence problem and give
polarizations naturally for arbitrarily complicated multi-scale fluid plasma
with arbitrary number of components. Attempt to kinetic plasma via $N$-point
Pad\'e approximation of plasma dispersion function also shows good results.

categories: physics.plasm-ph astro-ph.SR physics.comp-ph physics.space-ph


title:
Time Lag in Intra-Day Variability of Sgr A* between the Light Curves at
  90 and 102GHz

abstract:
  We performed the observation of the flux densities of SgrA* at 90 and 102GHz
in order to detect the time lag between these frequencies using the Nobeyama
Millimeter Array, which was previously reported at lower frequencies. We
detected a radio flare during the observation period on 6 April 2005 and
calculated the z-transformed discrete correlation function between the light
curves. The time lag between these frequencies was not detected. If the
expanding plasma model which explains the time lag at lower frequencies is
valid, the light curve at 90GHz would be delayed with respect to the one at
102GHz. This result suggests that the plasma blobs ejected near the Galactic
Center black hole may be widely diverse especially in optical thickness.
Another possibility is that the major portion of the flux above 100GHz does not
originate from the blobs.


title: Pseudogap and charge dynamics in doped cuprates

abstract:
  Within the microscopic theory of the normal-state pseudogap state, the doping
and temperature dependence of the charge dynamics in doped cuprates is studied
in the whole doping range from the underdoped to heavily overdoped. The
conductivity spectrum in the underdoped and optimally doped regimes contains
the low-energy non-Drude peak and unusual midinfrared band. However, the
position of the midinfrared band shifts towards to the low-energy non-Drude
peak with increasing doping. In particular, the low-energy non-Drude peak
incorporates with the midinfrared band in the heavily overdoped regime, and
then the low-energy Drude behavior recovers. It is shown that the striking
behavior of the low-energy non-Drude peak and unusual midinfrared band in the
underdoped and optimally doped regimes is closely related to the emergence of
the doping and temperature dependence of the normal-state pseudogap.


title: Optical cloning of arbitrary images beyond the diffraction limits

abstract:
  Cloning of arbitrary images encoded onto the spatial profile of a laser beam
onto that of a second beam is theoretically investigated. The two fields couple
to an atomic lambda system in a coherent population trapping configuration. In
particular, the case in which the probe and control fields are of comparable
strength is considered. By considering more and more complex structures, we
eventually find that our method is suitable to clone arbitrary images, which we
demonstrated by a full numerical simulation of the propagation dynamics of both
applied fields in the atomic medium, with the three letters "CPT" encoded on
the initial control field profile. We find that the cloned structures have
feature sizes reduced by about a factor of 2 compared to the initial images,
consistent with a recent related experiment.


title: Luttinger liquid properties of the steady state after a quantum quench

abstract:
  We study the dynamics resulting out of an abrupt change of the two-particle
interaction in two models of closed one-dimensional Fermi systems: (a) the
field theoretical Tomonaga-Luttinger model and (b) a microscopic lattice model.
Using a nonperturbative approach which is controlled for small two-particle
interactions we are able to reach large times allowing us to access the
properties of the steady state of the lattice model. Comparing those to the
exact solution of the full dynamics in the Tomonaga-Luttinger model we provide
evidence for universal Luttinger liquid behavior.


title: Giant enhancement of spin pumping efficiency using Fe3Si ferromagnet

abstract:
  Spincurrentronics, which involves the generation, propagation and control of
spin currents, has attracted a great deal of attention because of the
possibility of realizing dissipation-free information propagation. Whereas
electrical generation of spin currents originally made the field of
spincurrentronics possible, and significant advances in spin-current devices
has been made, novel spin-current-generation approaches such as dynamical
methods have also been vigorously investigated. However, the low spin-current
generation efficiency associated with dynamical methods has impeded further
progress towards practical spin devices. Here we show that by introducing a
Heusler-type ferromagnetic material, Fe3Si, pure spin currents can be generated
about twenty times more efficiently using a dynamical method. This achievement
paves the way to the development of novel spin-based devices.


title: Electrical transport in C-doped GaAs nanowires: surface effects

abstract:
  The resistivity and the mobility of Carbon doped GaAs nanowires have been
studied for different doping concentrations. Surface effects have been
evaluated by comparing upassivated with passivated nanowires. We directly see
the influence of the surface: the pinning of the Fermi level and the consequent
existence of a depletion region lead to an increase of the mobility up to 30
cm^2/(V*s) for doping concentrations lower than 3*10^18 cm^-3. Electron beam
induced current measurements show that the minority carrier diffusion path can
be as high as 190 nm for passivated nanowires.


title: A Social Welfare Optimal Sequential Allocation Procedure

abstract:
  We consider a simple sequential allocation procedure for sharing indivisible
items between agents in which agents take turns to pick items. Supposing
additive utilities and independence between the agents, we show that the
expected utility of each agent is computable in polynomial time. Using this
result, we prove that the expected utilitarian social welfare is maximized when
agents take alternate turns. We also argue that this mechanism remains optimal
when agents behave strategically


title:
Conceptual Understanding of Computer Program Execution: Application to
  C++

abstract:
  A visual programming language uses pictorial tools such as diagrams to
represent its structural units and control stream. It is useful for enhancing
understanding, maintenance, verification, testing, and parallelism. This paper
proposes a diagrammatic methodology that produces a conceptual representation
of instructions for programming source codes. Without loss of generality in the
potential for using the methodology in a wider range of applications, this
paper focuses on using these diagrams in teaching of C++ programming. C++
programming constructs are represented in the proposed method in order to show
that it can provide a foundation for understanding the behavior of running
programs. Applying the method to actual C++ classes demonstrates that it
improves understanding of the activities in the computer system corresponding
to a C++ program.


title:
Bayesian crack detection in ultra high resolution multimodal images of
  paintings

abstract:
  The preservation of our cultural heritage is of paramount importance. Thanks
to recent developments in digital acquisition techniques, powerful image
analysis algorithms are developed which can be useful non-invasive tools to
assist in the restoration and preservation of art. In this paper we propose a
semi-supervised crack detection method that can be used for high-dimensional
acquisitions of paintings coming from different modalities. Our dataset
consists of a recently acquired collection of images of the Ghent Altarpiece
(1432), one of Northern Europe's most important art masterpieces. Our goal is
to build a classifier that is able to discern crack pixels from the background
consisting of non-crack pixels, making optimal use of the information that is
provided by each modality. To accomplish this we employ a recently developed
non-parametric Bayesian classifier, that uses tensor factorizations to
characterize any conditional probability. A prior is placed on the parameters
of the factorization such that every possible interaction between predictors is
allowed while still identifying a sparse subset among these predictors. The
proposed Bayesian classifier, which we will refer to as conditional Bayesian
tensor factorization or CBTF, is assessed by visually comparing classification
results with the Random Forest (RF) algorithm.


title: Ramification theory and perfectoid spaces

abstract:
  Let K and F be complete discrete valuation fields of residue characteristic
p>0. Let m be a positive integer no more than their absolute ramification
indices. Let s and t be their uniformizers. Let L/K and E/F be finite
extensions such that the modulo s^m of the extension O_L/O_K and modulo t^m of
O_E/O_F are isomorphic. Let j=<m be a positive rational number. In this paper,
we prove that the ramification of L/K is bounded by j if and only if the
ramification of E/F is bounded by j. As an application, we prove that the
categories of finite separable extensions of K and F whose ramifications are
bounded by j are equivalent to each other, which generalizes a theorem of
Deligne to the case of imperfect residue fields. We also show the compatibility
of Scholl's theory of higher fields of norms with the ramification theory of
Abbes-Saito, and the integrality of small Artin and Swan conductors of abelian
extensions of mixed characteristic.


title: PWA tools in Hadronic Spectroscopy

abstract:
  The mini-proceedings of the Workshop on PWA tools in Hadronic Spectroscopy
held in Mainz from February 18th to 20th, 2013.


title:
Towards an Extension of the 2-tuple Linguistic Model to Deal With
  Unbalanced Linguistic Term sets

abstract:
  In the domain of Computing with words (CW), fuzzy linguistic approaches are
known to be relevant in many decision-making problems. Indeed, they allow us to
model the human reasoning in replacing words, assessments, preferences,
choices, wishes... by ad hoc variables, such as fuzzy sets or more
sophisticated variables.
  This paper focuses on a particular model: Herrera & Martinez' 2-tuple
linguistic model and their approach to deal with unbalanced linguistic term
sets. It is interesting since the computations are accomplished without loss of
information while the results of the decision-making processes always refer to
the initial linguistic term set. They propose a fuzzy partition which
distributes data on the axis by using linguistic hierarchies to manage the
non-uniformity. However, the required input (especially the density around the
terms) taken by their fuzzy partition algorithm may be considered as too much
demanding in a real-world application, since density is not always easy to
determine. Moreover, in some limit cases (especially when two terms are very
closed semantically to each other), the partition doesn't comply with the data
themselves, it isn't close to the reality. Therefore we propose to modify the
required input, in order to offer a simpler and more faithful partition. We
have added an extension to the package jFuzzyLogic and to the corresponding
script language FCL. This extension supports both 2-tuple models: Herrera &
Martinez' and ours. In addition to the partition algorithm, we present two
aggregation algorithms: the arithmetic means and the addition. We also discuss
these kinds of 2-tuple models.


title: The atomic-level mechanism underlying the functionality of aquaporin-0

abstract:
  So far, more than 82,000 protein structures have been reported in the Protein
Data Bank, but the driving force and structures that allow for protein
functions have not been elucidated at the atomic level for even one protein. We
have been able to clarify that the inter-subunit hydrophobic interaction
driving the electrostatic opening of the pore in aquaporin 0 (AQP0). Aquaporins
are membrane channels for water and small non-ionic solutes found in animals,
plants, and microbes. The structures of aquaporins have high homology and
consist of homotetramers, each monomer of which has one pore for a water
channel. Each pore has two narrow portions: one is the narrowest constriction
region consisting of aromatic residues and an arginine (ar/R), and another is
two asparagine-proline-alanine (NPA) homolog portions. Here we show that an
inter-subunit hydrophobic interaction in AQP0 drives a stick portion consisting
of four amino acids toward the pore and the tip of the stick portion,
consisting of a nitrogen atom, opens the pore: that movement is the swing
mechanism (this http URL). The energetics and conformational change of amino
acids participating in the swing mechanism confirm this view. The swing
mechanism in which inter-subunit hydrophobic interactions in the tetramer drive
the on-off switching of the pore explains why aquaporins consist of tetramers.
Here, we report that experimental and molecular dynamics findings using various
mutants support this view of the swing mechanism. The finding that mutants of
amino acids in AQP2 corresponding to the stick of the swing mechanism cause
severe recessive nephrogenic diabetes insipidus (NDI) demonstrates the critical
role of the swing mechanism for the aquaporin function. We report first that
the inter-subunit hydrophobic interaction in aquaporin 0 drives the
electrostatic opening of the aquaporin pore at the atomic level.


title:
An improved chemical scheme for the reactions of atomic oxygen and
  simple unsaturated hydrocarbons - implications for star-forming regions

abstract:
  Recent laboratory experiments have demonstrated that, even though
contribution from other reaction channels cannot be neglected, unsaturated
hydrocarbons easily break their multiple C-C bonds to form CO after their
interactions with atomic oxygen. Here we present an upgraded chemical modelling
including a revision of the reactions between oxygen atoms and small
unsaturated hydrocarbons for different astrochemical environments. A first
conclusion is that towards hot cores/corinos atomic oxygen easily degrades
unsaturated hydrocarbons directly to CO or to its precursor species (such as
HCCO or HCO) and destroys the double or triple bond of alkenes and alkynes.
Therefore, environments rich in atomic oxygen at a relatively high temperature
are not expected to be rich in large unsaturated hydrocarbons or polycyclic
aromatic hydrocarbons. On the contrary, in O-poor and C-rich objects,
hydrocarbon growth can occur to a large extent. In addition, new radical
species, namely ketyl and vinoxy radicals, generated from other reaction
channels can influence the abundances of hydrocarbons towards hot cores. We,
therefore, suggest they should be included in the available databases.
Hydrocarbon column densities are calculated in the 10(13)-10(15) cm(-2) range,
in good agreement with their observed values, despite the small number of data
currently published in the literature.


title: Cubic fourfolds containing a plane and K3 surfaces of Picard rank two

abstract:
  We present some families of cubic hypersurfaces in $\mathbb P^5 (\mathbb C)$
containing a plane whose associated quadric bundle does not have a rational
section.


title: Transmission matrices in gl(N) & U_q(gl(N)) quantum spin chains

abstract:
  The gl(N) and U_q(gl(N)) quantum spin chains in the presence of integrable
spin impurities are considered. Within the Bethe ansatz formulation, we derive
the associated transmission amplitudes, and the corresponding transmission
matrices -representations of the underlying quadratic algebra- that physically
describe the interaction between the various particle-like excitations
displayed by these models and the spin impurity.

categories: hep-th cond-mat.stat-mech math-ph math.MP nlin.SI


title:
Clump mass function at an early stage of molecular cloud evolution: II.
  Galactic cloud complexes

abstract:
  The statistical approach for derivation of the clump mass function (ClMF)
developed by Donkov, Veltchev & Klessen is put to observational test through
comparison with mass distributions of clumps from molecular emission and dust
continuum maps of Galactic cloud complexes, obtained by various authors. The
results indicate gravitational boundedness of the dominant clump population,
with or without taking into account the contribution of their thermal and
magnetic energy. The ClMF can be presented by combination of two power-law
functions separated by a characteristic mass from about ten to hundreds solar
masses. The slope of the intermediate-mass ClMF is shallow and nearly constant
(-0.25 \gtrsim \Gamma_{IM} \gtrsim -0.55) while the high-mass part is fitted by
models that imply gravitationally unstable clumps and exhibit slopes in a
broader range (-0.9 \gtrsim \Gamma_{IM} \gtrsim -1.6), centered at the value of
the stellar initial mass function (\Gamma_{HM} \gtreqless -1.3).


title: Consensus for the Fip35 folding mechanism?

abstract:
  Recent advances in computational power and simulation programs finally
delivered the first examples of reversible folding for small proteins with an
all-atom description. But having at hand the atomistic details of the process
did not lead to a straightforward interpretation of the mechanism. For the case
of the Fip35 WW-domain where multiple long trajectories of 100 {\mu}s are
available from D. E. Shaw Research, different interpretations emerged. Some of
those are in clear contradiction with each other while others are in
qualitative agreement. Here, we present a network-based analysis of the same
data by looking at the local fluctuations of conventional order parameters for
folding. We found that folding occurs through two major pathways, one almost
four times more populated than the other. Each pathway involves the formation
of an intermediate with one of the two hairpins in a native configuration. The
quantitative agreement of our results with a state-of-the-art reaction
coordinate optimization procedure as well as qualitative agreement with other
Markov-state-models and different simulation schemes provides strong evidence
for a multiple folding pathways scenario with the presence of intermediates.

categories: physics.bio-ph cond-mat.stat-mech physics.chem-ph q-bio.BM


title:
Time-dependent restricted-active-space self-consistent field theory for
  laser-driven many-electron dynamics

abstract:
  We present the time-dependent restricted-active-space self-consistent field
(TD-RASSCF) theory as a new framework for the time-dependent many-electron
problem. The theory generalizes the multiconfigurational time-dependent
Hartree-Fock (MCTDHF) theory by incorporating the restricted-active-space
scheme well known in time-independent quantum chemistry. Optimization of the
orbitals as well as the expansion coefficients at each time step makes it
possible to construct the wave function accurately while using only a
relatively small number of electronic configurations. In numerical calculations
of high-order harmonic generation spectra of a one-dimensional model of atomic
beryllium interacting with a strong laser pulse, the TD-RASSCF method is
reasonably accurate while largely reducing the computational complexity. The
TD-RASSCF method has the potential to treat large atoms and molecules beyond
the capability of the MCTDHF method.


title:
Bayesian abstract fuzzy economies, random quasi-variational inequalities
  with random fuzzy mappings and random fixed point theorems

abstract:
  In this paper, we introduce an abstract fuzzy economy model with a measure
space of agents which generalizes Patriche's model (2009), we obtain a theorem
of fuzzy equilibrium existence and we prove the existence of the solutions for
two types of random quasi-variational inequalities with random fuzzy mappings.
As a consequence, we obtain random fixed point theorems.


title:
Thermodynamics of rotating charged dilaton black holes in an external
  magnetic field

abstract:
  In the present paper we study the long-standing problem for the
thermodynamics of magnetized dilaton black holes. For this purpose we construct
an exact solution describing a rotating charged dilaton black hole immersed in
an external magnetic field and discuss its basic properties. We derive a
Smarr-like relation and the thermodynamics first law for these magnetized black
holes. The novelty in the thermodynamics of the magnetized black holes is the
appearance of new terms proportional to the magnetic momentum of the black
holes in the Smarr-like relation and the first law.


title: Commuting Squares and Index for Subfactors

abstract:
  This is the 1990 Ph.D. thesis of John Kehlet Schou, advised by Uffe Haagerup
at Odense University.


title:
An Introduction to Gauge Gravity Duality and Its Application in
  Condensed Matter

abstract:
  The past few years have witnessed a remarkable crossover of string
theoretical ideas from the abstract world of geometrical forms to the concrete
experimental realm of condensed matter physics. The basis for this ---
variously known as holography, the AdS/CFT correspondence or gauge-gravity
duality --comes from notions right at the cutting edge of string theory.
Nevertheless, the insights afforded can often be expressed in ways very
familiar to condensed matter physicists, such as relationships between response
functions and new sum rules.
  The aim of this short, introductory review is to survey the ideas
underpinning this crossover, in a way that -- as far as possible -- strips them
of sophisticated mathematical formalism, whilst at the same time retaining
their fundamental essence. I will sketch the areas in which progress has been
made to date and highlight where the challenges and open questions lie.
Finally, I will attempt to give a perspective upon these ideas. What
contribution can we realistically expect from this approach and how might it be
accommodated into the canon of condensed matter theory? Inevitably, any attempt
to do this in such a rapidly evolving field will be superseded by events.
Nevertheless, I hope that this will provide a useful way to think about
gauge-gravity duality and the uncharted directions in which it might take us.


title: Braided equivariant crossed modules and cohomology of $\Gamma $-modules

abstract:
  If $\Gamma $ is a group, then braided $\Gamma $-crossed modules are
classified by braided strict $\Gamma $-graded categorial groups. The Schreier
theory obtained for $\Gamma $-module extensions of the type of an abelian
$\Gamma $-crossed module is a generalization of the theory of $\Gamma $-module
extensions.


title:
On fixed-polynomial size circuit lower bounds for uniform polynomials in
  the sense of Valiant

abstract:
  Assuming the Generalised Riemann Hypothesis (GRH), we show that for all k,
there exist polynomials with coefficients in $\MA$ having no arithmetic
circuits of size O(n^k) over the complex field (allowing any complex constant).
We also build a family of polynomials that can be evaluated in AM having no
arithmetic circuits of size O(n^k). Then we investigate the link between
fixed-polynomial size circuit bounds in the Boolean and arithmetic settings. In
characteristic zero, it is proved that $\NP \not\subset \size(n^k)$, or $\MA
\subset \size(n^k)$, or NP=MA imply lower bounds on the circuit size of uniform
polynomials in n variables from the class VNP over the complex field, assuming
GRH. In positive characteristic p, uniform polynomials in VNP have circuits of
fixed-polynomial size if and only if both VP=VNP over F_p and Mod_pP has
circuits of fixed-polynomial size.


title: A refinement of the generalized chordal distance

abstract:
  For single input single output systems, we give a refinement of the
generalized chordal metric. Our metric is given in terms of coprime
factorizations, but it coincides with the extension of Vinnicombe's nu-metric
given in earlier work by Ball and Sasane if the coprime factorizations happens
to be normalized. The advantage of the metric introduced in this article is its
easy computability (since it relies only on coprime factorizations, and does
not require normalized coprime factorizations). We also give concrete
formulations of our abstract metric for standard classes of stable transfer
functions.


title: Front speed in reactive compressible stirred media

abstract:
  We investigated a nonlinear advection-diffusion-reaction equation for a
passive scalar field. The purpose is to understand how the compressibility can
affect the front dynamics and the bulk burning rate. We study two classes of
flows: periodic shear flow and cellular flow both in the case of fast advection
regime, analysing the system at varying the extent of compressibility and the
reaction rate. We find that the bulk burning rate in a shear flow increases
with compressibility intensity.
  Furthermore, the faster the reaction the more important the difference with
respect to the laminar case. The effect has been quantitatively measured and it
turns out to be generally little. For the cellular flow, the two extreme cases
have been investigated, with the whole perturbation situated either in the
centre of the vortex or in the periphery. The dependence in this case does not
show a monotonic scaling with different behaviour in the two cases. The
enhancing remains modest and always less than 20%


title: How to Resum Feynman Graphs

abstract:
  In this paper we reformulate in a simpler way the combinatoric core of
constructive quantum field theory We define universal rational combinatoric
weights for pairs made of a graph and one of its spanning trees. These weights
are nothing but the percentage of Hepp's sectors in which the tree is leading
the ultraviolet analysis. We explain how they allow to reshuffle the divergent
series formulated in terms of Feynman graphs into convergent series indexed by
the trees that these graphs contain. The Feynman graphs to be used are not the
ordinary ones but those of the intermediate field representation, and the
result of the reshuffling is called the Loop Vertex Expansion.


title:
Optical study of electron-electron exchange interaction in CdTe/ZnTe
  quantum dots

abstract:
  We present an experimental study of electron-electron exchange interaction in
self-assembled CdTe/ZnTe quantum dots based on the photoluminescence
measurements. The character and strength of this interaction are obtained by
simultaneous observation of various recombination channels of a doubly
negatively charged exciton, including previously unrecognized emission lines
related to the electron-singlet configuration in the final state. A typical
value of the electron singlet-triplet splitting, which corresponds to the
exchange integral of electron-electron interaction, has been determined as 20.4
meV with a spread of 1.4 meV across the wide population of quantum dots. We
also evidence an unexpected decrease of energy difference between the singlet
and triplet states under a magnetic field in Faraday geometry.


title: 2.5PN kick from black-hole binaries in circular orbit: Nonspinning case

abstract:
  Using the Multipolar post-Minskowskian formalism, we compute the linear
momentum flux from black-hole binaries in circular orbits and having no spins.
The total linear momentum flux contains various types of instantaneous (which
are functions of the retarded time) and hereditary (which depends on the
dynamics of the binary in the past) terms both of which are analytically
computed. In addition to the inspiral contribution, we use a simple model of
plunge to compute the kick or recoil accumulated during this phase.


title:
A complete transformation rule set and a minimal equation set for
  CNOT-based 3-qubit quantum circuits (Draft)

abstract:
  We introduce a complete transformation rule set and a minimal equation set
for controlled-NOT (CNOT)-based quantum circuits. Using these rules, quantum
circuits that compute the same Boolean function are reduced to the same normal
form. We can thus easily check the equivalence of circuits by comparing their
normal forms. By applying the Knuth-Bendix completion algorithm to a set of
modified 18 equations introduced by Iwama et al. 2002, we obtain a complete
transformation rule set (i.e., a set of transformation rules with the
properties of `termination' and `confluence'). Our transformation rule set
consists of 114 rules. Moreover, we discovered a minimal combination of
equations for the initial equation set.


title: Exact dynamics of one-qubit system in layered environment

abstract:
  We investigate the exact evolution of the reduced dynamics of a one qubit
system as central spin coupled to a femionic layered environment with unlimited
number of layers. Also, we study the decoherence induced on central spin by
analysis solution is obtained in the limit $N\rightarrow\infty$ of an infinite
number of bath spins. Finally, the Nakajima-Zwanzig (NZ) and the
time-convolutionless (TCL) projection operator techniques to second order are
derived.


title:
Kraus representation for maps and master equation in spin star model
  with layered environment

abstract:
  Quantum operations are usually defined as completely positive (CP), trace
preserving (TP) maps on quantum states, and can be represented by operator-sum
or Kraus representations. In this paper, we calculate operator-sum
representation and master equation of an exactly solvable dynamic of one-qubit
open system in layered environment . On the other hand, we obtain exact
Nakajima-Zwanzig (NZ) and time-convolutionless (TCL) master equation from the
maps. Finally, we study a simple example to consider the relation between CP
maps and initial quantum correlation and show that vanishing initial quantum
correlation is not necessary for CP maps.


title: Feedback Control of Rabi Oscillations in Circuit QED

abstract:
  We consider the feedback stabilization of Rabi oscillations in a
superconducting qubit which is coupled to a microwave readout cavity. The
signal is readout by homodyne detection of the in-phase quadrature amplitude of
the weak measurement output. By multiplying the time-delayed Rabi reference,
one can extract the signal, with maximum signal-to-noise ratio, from the noise.
We further track and stabilize the Rabi oscillations by using Lyapunov feedback
control to properly adjust the input Rabi drives. Theoretical and simulation
results illustrate the effectiveness of the proposed control law.


title:
Orbital entanglement production in Andreev billiards with time-reversal
  symmetry

abstract:
  We study orbital entanglement production in a chaotic cavity connected to
four single-channel normal-metal leads and one superconducting lead, assuming
the presence of time-reversal symmetry (TRS). The scattered state of two
incident electrons is written as the superposition of several two-outgoing
quasi-particle states, four of which are orbitally entangled in a left-right
bipartition. We calculate numerically the mean value of the squared norm of
each scattered state's component, as functions of the number of channels in the
superconducting lead. Its behavior is explained as resulting from the proximity
effect. We also study statistically the amount of entanglement carried by each
pair of outgoing quasi-particles. When the influence of the superconductor is
more intense, the average entanglement is found to be considerably larger than
that obtained using normal cavities.


title:
Dichotomous Hamiltonians with Unbounded Entries and Solutions of Riccati
  Equations

abstract:
  An operator Riccati equation from systems theory is considered in the case
that all entries of the associated Hamiltonian are unbounded. Using a certain
dichotomy property of the Hamiltonian and its symmetry with respect to two
different indefinite inner products, we prove the existence of nonnegative and
nonpositive solutions of the Riccati equation. Moreover, conditions for the
boundedness and uniqueness of these solutions are established.


title: Units in Grothendieck-Witt rings and A^1-spherical fibrations

abstract:
  In this note, we show that the units in Grothendieck-Witt rings extend to an
unramified strictly A^1-invariant sheaf of abelian groups on the category of
smooth schemes. This implies that there is an A^1-local classifying space of
spherical fibrations.


title:
Numerical solving the identification problem for the lower coefficient
  of parabolic equation

abstract:
  In the theory and practice of inverse problems for partial differential
equations (PDEs) much attention is paid to the problem of the identification of
coefficients from some additional information. This work deals with the problem
of determining in a multidimensional parabolic equation the lower coefficient
that depends on time only. To solve numerically a nonlinear inverse problem,
linearized approximations in time are constructed using standard finite element
procedures in space. The computational algorithm is based on a special
decomposition, where the transition to a new time level is implemented via
solving two standard elliptic problems. The numerical results presented here
for a model 2D problem demonstrate capabilities of the proposed computational
algorithms for approximate solving inverse problems.


title: Note on Totally Skew Embeddings of Quasitoric Manifolds over Cube

abstract:
  Totally skew embeddings are introduced by Ghomi and Tabachnikov. They are
naturally related to classical problems in topology, such as the generalized
vector field problem and the immersion problem for real projective spaces. In
recent paper Topological obstructions to totally skew embeddings, {totaly skew}
embeddings are studied by using the Stiefel-Whitney classes In the same paper
it is conjectured that for every $n$-dimensional, compact smooth manifold $M^n$
$(n>1)$, $$N(M^n)\leq 4n-2\alpha (n)+1,$$ where $N(M^n)$ is defined as the
smallest dimension $N$ such that there exists a {\em totally skew} embedding of
a smooth manifold $M^n$ in $\mathbb{R}^N$.
  We prove that for every $n$, there is a quasitoric manifold $Q^{2n}$ for
which the orbit space of $T^n$ action is a cube $I^n$ and $$N(Q^{2n})\geq
8n-4\alpha (n)+1.$$ Using the combinatorial properties of cohomology ring $H^*
(Q^{2n}, \mathbb{Z}_2)$, we construct an interesting general non-trivial
example different from known example of the product of complex projective
spaces.


title: Measures of quantum synchronization in continuous variable systems

abstract:
  We introduce and characterize two different measures which quantify the level
of synchronization of interacting continuous variable quantum systems. The two
measures allow to extend to the quantum domain the notions of complete and
phase synchronization. The Heisenberg principle sets a universal bound to
complete synchronization. The measure of phase synchronization is in principle
unbounded, however in the absence of quantum resources (e.g. squeezing) the
synchronization level is bounded below a certain threshold. We elucidate some
interesting connections between entanglement and synchronization and, finally,
discuss an application based on quantum opto-mechanical systems.


title: Transverse charge densities in the nucleon in nuclear matter

abstract:
  We investigated the transverse charge densities in the nucleon in nuclear
matter within the framework of the in-medium modified Skyrme model. The medium
modification of the nucleon electromagnetic form factors are first discussed.
The results show that the form factors in nuclear matter fall off faster than
those in free space, as the momentum transfer increases. As a result, the
charge radii of the nucleon become larger, as the nuclear matter density
increases. The transverse charge densities in the nucleon indicate that the
size of the nucleon tends to bulge out in nuclear matter. This salient feature
of the swelling is more clearly observed in the neutron case. When the proton
is transversely polarized, the transverse charge densities exhibit the
distortion due to the effects of the magnetization.


title:
Deformation and cluster structures in $^{12}$C studied with
  configuration mixing using Skyrme interactions

abstract:
  We report an investigation of the structure of $^{12}$C nucleus employing a
newly developed configuration-mixing method. In the three-dimensional
coordinate-space representation, we generate a number of Slater determinants
with various correlated structures using the imaginary-time algorithm. We then
diagonalize a many-body Hamiltonian with the Skyrme interaction in the space
spanned by the Slater determinants with parity and angular momentum
projections. Our calculation reasonably describes the ground and excited states
of $^{12}$C nucleus, both for shell-model-like and cluster-like states. The
excitation energies and transition strengths of the ground-state rotational
band are well reproduced. Negative parity excited states, $1_1^-$, $2_1^-$, and
$3_1^-$, are also reasonably described. The second and third $0^+$ states,
$0_2^+$ and $0_3^+$, appear at around 8.8 MeV and 15 MeV, respectively. The
$0_2^+$ state shows a structure consistent with former results of the
\alpha-cluster models, however, the calculated radius of the $0_2^+$ state is
smaller than those calculations. The three-{\alpha} linear-chain configuration
dominates in the $0_3^+$ state.


title: Mapping spaces and R-completion

abstract:
  We study the questions of how to recognize when a simplicial set X is of the
form X=map(Y,A) for a given space A, and how to recover Y from X, if so. A full
answer is provided when A=K(R,n), for $R=\mathbb{F}_p$ or $\mathbb{Q}$, in
terms of a mapping algebra structure on X (defined in terms of
product-preserving simplicial functors out of a certain simplicially-enriched
sketch). In addition, when A is a suitable infinite loop space for a suitable
connective ring spectrum, we can recover Y from map(Y,A) given such a mapping
algebra structure. Most importantly, our methods provide a new way of looking
at the classical Bousfield-Kan R-completion.


title:
Asymptotic properties of the MLE for the autoregressive process
  coefficients under stationary Gaussian noise

abstract:
  In this paper we are interested in the Maximum Likelihood Estimator (MLE) of
the vector parameter of an autoregressive process of order $p$ with regular
stationary Gaussian noise. We exhibit the large sample asymptotical properties
of the MLE under very mild conditions. Simulations are done for fractional
Gaussian noise (fGn), autoregressive noise (AR(1)) and moving average noise
(MA(1)).


title: $L^2$-Riemann-Roch for singular complex curves

abstract:
  We present a comprehensive $L^2$-theory for the $\overline\partial$-operator
on singular complex curves, including $L^2$-versions of the Riemann-Roch
theorem and some applications.


title: Entanglement rates and area laws

abstract:
  We prove an upper bound on the maximal rate at which a Hamiltonian
interaction can generate entanglement in a bipartite system. The scaling of
this bound as a function of the subsystem dimension on which the Hamiltonian
acts nontrivially is optimal and is exponentially improved over previously
known bounds. As an application, we show that a gapped quantum many-body spin
system on an arbitrary lattice satisfies an area law for the entanglement
entropy if and only if any other state with which it is adiabatically connected
(i.e. any state in the same phase) also satisfies an area law.

categories: quant-ph cond-mat.str-el math-ph math.MP


title: Phase Transition of Random Non-Uniform Hypergraphs

abstract:
  Non-uniform hypergraphs appear in various domains of computer science as in
the satisfiability problems and in data analysis. We analyse a general model
where the probability for an edge of size $t$ to belong to the hypergraph
depends of a parameter $\omega_t$ of the model. It is a natural generalization
of the models of graphs presented in "The first cycles in an evolving graph"
[Flajolet, Knuth, Pittel, 1989] and in the "Birth of the giant component"
[Janson, Knuth, \L{}uczak, Pittel, 1993]. The present paper follows the same
general approach based on analytic combinatorics. We show that many analytic
tools developed for the analysis of graphs can be extended surprisingly well to
non-uniform hypergraphs. Specifically, we investigate random hypergraphs with a
large number of vertices $n$ and a complexity, defined as the "excess",
proportional to $n$. We analyze their typical structure before, near and after
the birth of the "complex" components, that are the connected components with
more than one cycle. Finally, we compute statistics of the model to link number
of edges and excess.


title:
Probing spin entanglement by gate-voltage-controlled interference of
  current correlation in quantum spin Hall insulators

abstract:
  We propose an entanglement detector composed of two quantum spin Hall
insulators and a side gate deposited on one of the edge channels. For an ac
gate voltage, the differential noise contributed from the entangled electron
pairs exhibits the nontrivial step structures, from which the spin entanglement
concurrence can be easily obtained. The possible spin dephasing effects in the
quantum spin Hall insulators are also included.


title: On Partial Vertex Cover on Bipartite Graphs and Trees

abstract:
  It is well-known that the Vertex Cover problem is in P on bipartite graphs,
however; the computational complexity of the Partial Vertex Cover problem on
bipartite graphs is open. In this paper, we first show that the Partial Vertex
Cover problem is NP-hard on bipartite graphs. We then identify an interesting
special case of bipartite graphs, for which the Partial Vertex Cover problem
can be solved in polynomial-time. We also show that the set of acyclic
bipartite graphs, i.e., forests, and the set of bipartite graph where the
degree of each vertex is at most 3 fall into that special case. Therefore, we
prove that the Partial Vertex Cover problem is in P on trees, and it is also in
P on the set of bipartite graphs where the degree of each vertex is at most 3.


title: Quantum Skew Divergence

abstract:
  In this paper we study the quantum generalisation of the skew divergence,
which is a dissimilarity measure between distributions introduced by L. Lee in
the context of natural language processing. We provide an in-depth study of the
quantum skew divergence, including its relation to other state
distinguishability measures. Finally, we present a number of important
applications: new continuity inequalities for the quantum Jensen-Shannon
divergence and the Holevo information, and a new and short proof of Bravyi's
Small Incremental Mixing conjecture.


title: Gluon mass generation in the presence of dynamical quarks

abstract:
  We study in detail the impact of dynamical quarks on the gluon mass
generation mechanism, in the Landau gauge, for the case of a small number of
quark families. As in earlier considerations, we assume that the main bulk of
the unquenching corrections to the gluon propagator originates from the fully
dressed quark-loop diagram. The nonperturbative evaluation of this diagram
provides the key relation that expresses the unquenched gluon propagator as a
deviation from its quenched counterpart. This relation is subsequently coupled
to the integral equation that controls the momentum evolution of the effective
gluon mass, which contains a single adjustable parameter; this constitutes a
major improvement compared to the analysis presented in Phys. Rev. D86 (2012)
014032, where the behaviour of the gluon propagator in the deep infrared was
estimated through numerical extrapolation. The resulting nonlinear system is
then treated numerically, yielding unique solutions for the modified gluon mass
and the quenched gluon propagator, which fully confirm the picture put forth
recently in several continuum and lattice studies. In particular, an infrared
finite gluon propagator emerges, whose saturation point is considerably
suppressed, due to a corresponding increase in the value of the gluon mass.
This characteristic feature becomes more pronounced as the number of active
quark families increases, and can be deduced from the infrared structure of the
kernel entering in the gluon mass equation.


title: A Light Dynamical Scalar Boson

abstract:
  With the discovery of a scalar resonance at ATLAS and CMS, the understanding
of the electroweak symmetry breaking origin seems a much closer goal. A strong
dynamics at relatively low scales is still a good candidate. In this talk, the
complete effective Lagrangian up to d < 6 will be presented, both for the gauge
and the flavour sectors. Interesting features in the flavour phenomenology will
be discussed.


title:
Security Policies for WFMS with Rich Business Logic - A Model Suitable
  for Analysis

abstract:
  This paper introduces a formal metamodel for the specification of security
policies for workflows in online service systems designed to be suitable for
the modeling and analysis of complex business-related rules as well as
traditional access control. A translation of the model into a colored Petri net
is shown and an example of policy for an online banking system is described. By
writing predicates for querying the resulting state-space of the Petri net, a
connection between the formalized model and a higher-level description of the
security policy can be made, indicating the feasibility of the intended method
for validating such descriptions. Thanks to the independent nature among tasks
related to different business services, represented by restrictions in the
information flow within the metamodel, the state-space may be fractioned for
analysis, avoiding the state-space explosion problem. Related existing models
are discussed, pointing the gain in expressiveness of business rules and the
analysis of insecure state paths rather than simply insecure states in the
proposed model. The successful representation and analysis of the policy from
the example combined with reasonings for the general case attest the adequacy
of the proposed approach for its intended application.


title: Exact and asymptotically robust permutation tests

abstract:
  Given independent samples from P and Q, two-sample permutation tests allow
one to construct exact level tests when the null hypothesis is P=Q. On the
other hand, when comparing or testing particular parameters $\theta$ of P and
Q, such as their means or medians, permutation tests need not be level
$\alpha$, or even approximately level $\alpha$ in large samples. Under very
weak assumptions for comparing estimators, we provide a general test procedure
whereby the asymptotic validity of the permutation test holds while retaining
the exact rejection probability $\alpha$ in finite samples when the underlying
distributions are identical. The ideas are broadly applicable and special
attention is given to the k-sample problem of comparing general parameters,
whereby a permutation test is constructed which is exact level $\alpha$ under
the hypothesis of identical distributions, but has asymptotic rejection
probability $\alpha$ under the more general null hypothesis of equality of
parameters. A Monte Carlo simulation study is performed as well. A quite
general theory is possible based on a coupling construction, as well as a key
contiguity argument for the multinomial and multivariate hypergeometric
distributions.


title:
Low-Complexity Channel Estimation in Large-Scale MIMO using Polynomial
  Expansion

abstract:
  This paper considers pilot-based channel estimation in large-scale
multiple-input multiple-output (MIMO) communication systems, also known as
"massive MIMO". Unlike previous works on this topic, which mainly considered
the impact of inter-cell disturbance due to pilot reuse (so-called pilot
contamination), we are concerned with the computational complexity. The
conventional minimum mean square error (MMSE) and minimum variance unbiased
(MVU) channel estimators rely on inverting covariance matrices, which has cubic
complexity in the multiplication of number of antennas at each side. Since this
is extremely expensive when there are hundreds of antennas, we propose to
approximate the inversion by an L-order matrix polynomial. A set of
low-complexity Bayesian channel estimators, coined Polynomial ExpAnsion CHannel
(PEACH) estimators, are introduced. The coefficients of the polynomials are
optimized to yield small mean square error (MSE). We show numerically that
near-optimal performance is achieved with low polynomial orders. In practice,
the order L can be selected to balance between complexity and MSE.
Interestingly, pilot contamination is beneficial to the PEACH estimators in the
sense that smaller L can be used to achieve near-optimal MSEs.


title: The Boussinesq approximation in rapidly rotating flows

abstract:
  In commonly used formulations of the Boussinesq approximation centrifugal
buoyancy effects related to differential rotation, as well as strong vortices
in the flow, are neglected. However, these may play an important role in
rapidly rotating flows, such as in astrophysical and geophysical applications,
and also in turbulent convection. We here provide a straightforward approach
resulting in a Boussinesq-type approximation that consistently accounts for
centrifugal effects. Its application to the accretion-disk problem is
discussed. We numerically compare the new approach to the typical one in fluid
flows confined between two differentially heated and rotating cylinders. The
results justify the need of using the proposed approximation in rapidly
rotating flows.


title: Heuristics for the data arrangement problem on regular trees

abstract:
  The data arrangement problem on regular trees (DAPT) consists in assigning
the vertices of a given graph G to the leaves of a d-regular tree T such that
the sum of the pairwise distances of all pairs of leaves in T which correspond
to edges of G is minimised. Luczak and Noble [6] have shown that this problem
is NP-hard for every fixed d larger than or equal to 2. In this paper we
propose construction and local search heuristics for the DAPT and introduce a
lower bound for this problem. The analysis of the performance of the heuristics
is based on two considerations: a) the quality of the solutions produced by the
heuristics as compared to the respective lower bounds b) for a special class of
instances with known optimal solution we evaluate the gap between the optimal
value of the objective function and the objective function value attained by
the heuristic solution, respectively.


title:
On the conditional distributions of low-dimensional projections from
  high-dimensional data

abstract:
  We study the conditional distribution of low-dimensional projections from
high-dimensional data, where the conditioning is on other low-dimensional
projections. To fix ideas, consider a random d-vector Z that has a Lebesgue
density and that is standardized so that $\mathbb{E}Z=0$ and
$\mathbb{E}ZZ'=I_d$. Moreover, consider two projections defined by unit-vectors
$\alpha$ and $\beta$, namely a response $y=\alpha'Z$ and an explanatory
variable $x=\beta'Z$. It has long been known that the conditional mean of y
given x is approximately linear in x$ under some regularity conditions; cf.
Hall and Li [Ann. Statist. 21 (1993) 867-889]. However, a corresponding result
for the conditional variance has not been available so far. We here show that
the conditional variance of y given x is approximately constant in x (again,
under some regularity conditions). These results hold uniformly in $\alpha$ and
for most $\beta$'s, provided only that the dimension of Z is large. In that
sense, we see that most linear submodels of a high-dimensional overall model
are approximately correct. Our findings provide new insights in a variety of
modeling scenarios. We discuss several examples, including sliced inverse
regression, sliced average variance estimation, generalized linear models under
potential link violation, and sparse linear modeling.


title: Efficient atomic clocks operated with several atomic ensembles

abstract:
  Atomic clocks are typically operated by locking a local oscillator (LO) to a
single atomic ensemble. In this article we propose a scheme where the LO is
locked to several atomic ensembles instead of one. This results in an
exponential improvement compared to the conventional method and provides a
stability of the clock scaling as $(\alpha N)^{-m/2}$ with $N$ being the number
of atoms in each of the $m$ ensembles and $\alpha$ is a constant depending on
the protocol being used to lock the LO


title:
Full Jet Reconstruction in 2.76 TeV pp and Pb-Pb collisions in the ALICE
  experiment

abstract:
  Measurements of the suppression of high-pT particles and the away-side jets
from heavy-ion collisions at RHIC have shown that medium-induced energy loss
affects partons produced in the early stage of a heavy-ion collision. At LHC
energies the initial production cross-section is much higher, which allows jets
to be reconstructed with a wide kinematic range. Measuring fully reconstructed
jets by taking advantage of the ALICE Electromagnetic Calorimeter allows for a
more differential investigation of the parton energy loss. Parton energy loss
will allow us to access key observables of the hot, dense matter created in
heavy ion collisions. The data presented was collected during the 2.76 TeV
Pb-Pb runs, as well as baseline measurements from the 2.76 TeV pp run. The
procedures used to reconstruct jets and extract them from a fluctuating
background will be discussed. The procedure for quantifying the background with
a limited acceptance will also be discussed. These results are compared to pp
measurements and simulations.


title: Comments on double field theory and diffeomorphisms

abstract:
  As the theory is subject to a section condition, coordinates in double field
theory do not represent physical points in an injective manner. We argue that a
physical point should be rather one-to-one identified with a `gauge orbit' in
the coordinate space. The diffeomorphism symmetry then implies an invariance
under arbitrary reparametrizations of the gauge orbits. Within this generalized
sense of diffeomorphism, we show that a recently proposed tensorial
transformation rule for finite coordinate transformations is actually (i)
consistent with the standard exponential map, and further (ii) compatible with
the full covariance of the `semi-covariant' derivatives and curvatures after
projectors are properly imposed.


title: How Cations Change Peptide Structure

abstract:
  Specific interactions between cations and proteins have a strong impact on
peptide and protein structure. We here shed light on the nature of the
underlying interactions, especially regarding the effects on the polyamide
backbone structure. To do so, we compare the conformational ensembles of model
peptides in isolation and in the presence of either Li+ or Na+ cations by
state-of-the-art density-functional theory (including van der Waals effects)
and gas-phase infrared spectroscopy. These monovalent cations have a drastic
effect on the local backbone conformation of turn-forming peptides, by
disruption of the H bonding networks and the resulting severe distortion of the
backbone conformations. In fact, Li+ and Na+ can even have different
conformational effects on the same peptide. We also assess the predictive power
of current approximate density functionals for peptide-cation systems and
compare to results from established protein force fields as well as to
high-level quantum chemistry (CCSD(T)).


title:
From the SrTiO3 Surface to the LAlO3/SrTiO3 Interface: How thickness is
  critical

abstract:
  Novel properties arising at interfaces between transition metal oxides,
particularly the conductivity at the interface of LaAlO3 (LAO) and SrTiO3 (STO)
band insulators, have generated new paradigms, challenges, and opportunities in
condensed matter physics. Conventional transport measurements have established
that intrinsic conductivity appears in LAO/STO interfaces when the LAO film
matches or exceeds a critical thickness of 4 unit cells (uc). Recently, a
number of experiments raise important questions about the role of the LAO film,
the influence of photons, and the effective differences between vacuum/STO and
LAO/STO, both above and below the standard critical thickness. Here, using
angle-resolved photoemission spectroscopy (ARPES) on in situ prepared samples,
as well as resonant inelastic x-ray scattering (RIXS), we study how the
metallic STO surface state evolves during the growth of a crystalline LAO film.
In all the samples, the character of the conduction bands, their carrier
densities, the Ti3+ crystal fields, and the responses to photon irradiation
bear strong similarities. However, LAO/STO interfaces exhibit intrinsic
instability toward in-plane folding of the Fermi surface at and above the 4-uc
thickness threshold. This ordering distinguishes these heterostructures from
bare STO and sub-critical-thickness LAO/STO and coincides with the onset of
unique properties such as magnetism and built-in conductivity.


title: Birational maps of 3-folds

abstract:
  We show that 3-fold terminal flips and divisorial contractions may be
factored into a sequence of flops, blow-downs to a smooth curve in a smooth
3-fold or divisorial contractions to points with minimal discrepancies.