title:
H-Spaces, Loop Spaces and the Space of Positive Scalar Curvature Metrics
  on the Sphere

abstract:
  For dimensions n greater than or equal to 3, we show that the space of
metrics of positive scalar curvature on the n-sphere is homotopy equivalent to
a subspace which takes the form of a H-space with a homotopy commutative,
homotopy associative product operation. This product operation is based on the
connected sum construction. We then exhibit an action of the little n-disks
operad on this subspace which, using results of Boardman, Vogt and May implies
that when n=3 or n is at least 5, the space of metrics of positive scalar
curvature on the n-sphere is weakly homotopy equivalent to an n-fold loop
space.


title: Demagnetized Electron Heating at Collisionless Shocks

abstract:
  Seventy measurements of electron heating at the Earth's quasi-perpendicular
bow shock are analyzed in terms of Maxwellian-temperatures obtained from fits
to the core electrons that separate thermal heating from supra-thermal
acceleration. The perpendicular temperatures are both greater and lesser than
expected for adiabatic compression. The average parallel and perpendicular
heating is the same. These results are explained because, over the electron
gyroradius, $\delta B/B\sim 1$ and $e\delta \phi/T_e\sim 1$, so electron
trajectories are more random and chaotic than adiabatic. Because density
fluctuations are also large, trapping and wave growth in density holes may be
important.


title: Class polynomials for nonholomorphic modular functions

abstract:
  We give algorithms for computing the singular moduli of suitable
nonholomorphic modular functions F(z). By combining the theory of isogeny
volcanoes with a beautiful observation of Masser concerning the nonholomorphic
Eisenstein series E_2*(z), we obtain CRT-based algorithms that compute the
class polynomials H_D(F;x), whose roots are the discriminant D singular moduli
for F(z). By applying these results to a specific weak Maass form F_p(z), we
obtain a CRT-based algorithm for computing partition class polynomials, a
sequence of polynomials whose traces give the partition numbers p(n). Under the
GRH, the expected running time of this algorithm is O(n^{5/2+o(1)}). Key to
these results is a fast CRT-based algorithm for computing the classical modular
polynomial Phi_m(X,Y) that we obtain by extending the isogeny volcano approach
previously developed for prime values of m.


title: Brill-Noether with ramification at unassigned points

abstract:
  We discuss in this short note how basic facts about divisors on moduli spaces
of pointed curves give a solution to the Brill-Noether problem of nonexistence
of linear series with prescribed ramification at unassigned points.


title: A Note on Divisible Points of Curves

abstract:
  Let $C$ be an irreducible algebraic curve defined over a number field and
inside an algebraic torus of dimension at least 3. We partially answer a
question posed by Levin on points on $C$ for which a non-trivial power lies
again on $C$. Our results have connections to Zilber's Conjecture on
Intersections with Tori and yield to methods arising in transcendence theory
and the theory of o-minimal structures.


title: Electrodynamics of Perfect Conductors

abstract:
  The most general electrodynamic equations of a perfect conducting state are
obtained using a variational principle in a classical framework, following an
approach by Pierre-Gilles de Gennes. London equations are derived as the
time-independent case of these equations, corresponding to the magnetostatic
minimal energy state of the perfect conducting system. For further
confirmation, the same equations are also derived in the classical limit of the
Coleman-Weinberg model, the most successful quantum macroscopic theory of
superconductivity. The magnetic field expulsion is, therefore, a direct
consequence of zero resistivity and not an exclusive property of
superconductors.


title: Spatial Coupling as a Proof Technique

abstract:
  The aim of this paper is to show that spatial coupling can be viewed not only
as a means to build better graphical models, but also as a tool to better
understand uncoupled models. The starting point is the observation that some
asymptotic properties of graphical models are easier to prove in the case of
spatial coupling. In such cases, one can then use the so-called interpolation
method to transfer known results for the spatially coupled case to the
uncoupled one.
  Our main use of this framework is for LDPC codes, where we use interpolation
to show that the average entropy of the codeword conditioned on the observation
is asymptotically the same for spatially coupled as for uncoupled ensembles.
  We give three applications of this result for a large class of LDPC
ensembles. The first one is a proof of the so-called Maxwell construction
stating that the MAP threshold is equal to the Area threshold of the BP GEXIT
curve. The second is a proof of the equality between the BP and MAP GEXIT
curves above the MAP threshold. The third application is the intimately related
fact that the replica symmetric formula for the conditional entropy in the
infinite block length limit is exact.


title: Stripe Instabilities of Geometries with Hyperscaling Violation

abstract:
  We study the dynamical stripe instabilities on the geometries with
hyperscaling violation in the IR, which asymptotically approach AdS_4 in the
UV. The instabilities break the translational invariance spontaneously and are
induced by the axion term ~ a F \wedge F in the bulk action. We first study the
perturbation equations in the probe limit, and find that there is a strong
correlation between the stripe instabilities caused by the axion term and
parameters of the theories which determine the IR hyperscaling violation.
Contrary to the IR AdS_2 case, the effect of the axion term for the stripe
instabilities can be enhanced/suppressed at low temperature depending on the
parameters. For a certain one-parameter family of the hyperscaling violation,
we find the onset of the stripe instability analytically in the axion coupling
tuned model. For more generic parameter range of hyperscaling violation, we
study the instability onset by searching for the zero mode numerically on the
full geometries. We also argue that quite analogous results hold, after taking
into account the graviton fluctuation, i.e., beyond the probe limit.


title:
An entropy based thermalization scheme for hybrid simulations of Coulomb
  collisions

abstract:
  We formulate and test a hybrid fluid-Monte Carlo scheme for the treatment of
elastic collisions in gases and plasmas. While our primary focus and
demonstrations of applicability are for moderately collisional plasmas, as
described by the Landau-Fokker-Planck equation, the method is expected to be
applicable also to collision processes described by the Boltzmann equation.
This scheme is similar to the previously discussed velocity-based scheme [R.
Caflisch, et. al, Multiscale Modeling & Simulation 7, 865, (2008)] and the
scattering-angle-based scheme [A.M. Dimits, et. al, Bull. APS 55, no. 15 (2010,
Abstract: XP9.00006)], but with a firmer theoretical basis and without the
inherent limitation to the Landau-Fokker-Planck case. It gives a significant
performance improvement (e.g., error for a given computational effort) over the
velocity-based scheme. These features are achieved by assigning passive scalars
to each simulated particle and tracking their evolution through collisions. The
method permits a detailed error analysis that is confirmed by numerical
results. The tests performed are for the evolution from anisotropic Maxwellian
and a bump-on-tail distribution.


title: Pseudo-spherical Surfaces of Low Differentiability

abstract:
  We continue our investigations into Toda's algorithm [14,3]; a
Weierstrass-type representation of Gauss curvature $K=-1$ surfaces in
$\mathbb{R}^3$. We show that $C^0$ input potentials correspond in an appealing
way to a special new class of surfaces, with $K=-1$, which we call $C^{1M}$.
These are surfaces which may not be $C^2$, but whose mixed second partials are
continuous and equal. We also extend several results of Hartman-Wintner [5]
concerning special coordinate changes which increase differentiability of
immersions of $K=-1$ surfaces. We prove a $C^{1M}$ version of Hilbert's
Theorem.


title: Traveling Waves in a Three Species Competition-cooperation System

abstract:
  This paper studies the traveling wave solutions to a three species
competition cooperation system. The existence of the traveling waves is
investigated via monotone iteration method. The upper and lower solutions come
from either the waves of KPP equation or those of certain Lotka Volterra
system. We also derive the asymptotics and uniqueness of the wave solutions.
The results are then applied to a Lotka Volterra system with spatially averaged
and temporally delayed competition.


title: Ferromagnetism in itinerant two-dimensional t2g systems

abstract:
  Motivated by the recent indications of ferromagnetism in transition metal
oxide heterostructures, we propose a possible mechanism to generate
ferromagnetism for itinerant t2g systems in two spatial dimensions that does
not rely on the coupling between local moments and conduction electrons. We
particularly emphasize the orbital nature of different bands and show that,
when the Fermi level lies near the bottom of the upper bands, a
non-perturbative interaction effect due to the quasi-one-dimensional nature of
the upper bands may drive a transition to a state in which the upper bands are
ferromagnetically polarized. In the quasi-one-dimensional limit, the full
thermodynamics may be obtained exactly. We discuss the connection between our
mechanism with several itinerant t2g systems that may have ferromagnetic
instabilities.


title:
On the Mass Concentration for Bose-Einstein Condensates with Attractive
  Interactions

abstract:
  We consider two-dimensional Bose-Einstein condensates with attractive
interaction, described by the Gross-Pitaevskii functional. Minimizers of this
functional exist only if the interaction strength $a$ satisfies $a < a^*=
\|Q\|_2^2$, where $Q$ is the unique positive radial solution of $\Delta
u-u+u^3=0$ in $\R^2$. We present a detailed analysis of the behavior of
minimizers as $a$ approaches $a^*$, where all the mass concentrates at a global
minimum of the trapping potential.

categories: math-ph cond-mat.quant-gas math.FA math.MP


title: When is tit-for-tat unbeatable?

abstract:
  We characterize the class of symmetric two-player games in which tit-for-tat
cannot be beaten even by very sophisticated opponents in a repeated game. It
turns out to be the class of exact potential games. More generally, there is a
class of simple imitation rules that includes tit-for-tat but also
imitate-the-best and imitate-if-better. Every decision rule in this class is
essentially unbeatable in exact potential games. Our results apply to many
interesting games including all symmetric 2x2 games, and standard examples of
Cournot duopoly, price competition, public goods games, common pool resource
games, and minimum effort coordination games.


title: Computing sum of sources over an arbitrary multiple access channel

abstract:
  The problem of computing sum of sources over a multiple access channel (MAC)
is considered. Building on the technique of linear computation coding (LCC)
proposed by Nazer and Gastpar [2007], we employ the ensemble of nested coset
codes to derive a new set of sufficient conditions for computing the sum of
sources over an \textit{arbitrary} MAC. The optimality of nested coset codes
[Padakandla, Pradhan 2011] enables this technique outperform LCC even for
linear MAC with a structural match. Examples of nonadditive MAC for which the
technique proposed herein outperforms separation and systematic based
computation are also presented. Finally, this technique is enhanced by
incorporating separation based strategy, leading to a new set of sufficient
conditions for computing the sum over a MAC.


title:
Background Rejection in the DMTPC Dark Matter Search Using Charge
  Signals

abstract:
  The Dark Matter Time Projection Chamber (DMTPC) collaboration is developing a
low pressure gas TPC for detecting Weakly Interacting Massive Particle
(WIMP)-nucleon interactions. Optical readout with CCD cameras allows for the
detection of the daily modulation of the direction of the dark matter wind. In
order to reach sensitivities required for WIMP detection, the detector needs to
minimize backgrounds from electron recoils. This paper demonstrates that a
simplified CCD analysis achieves $7.3\times10^{-5}$ rejection of electron
recoils while a charge analysis yields an electron rejection factor of
$3.3\times10^{-4}$ for events with $^{241}$Am-equivalent ionization energy loss
between 40 keV and 200 keV. A combined charge and CCD analysis yields a
background-limited upper limit of $1.1\times10^{-5}$ (90% confidence level) for
the rejection of $\gamma$ and electron events. Backgrounds from alpha decays
from the field cage are eliminated by introducing a veto electrode that
surrounds the sensitive region in the TPC. CCD-specific backgrounds are reduced
more than two orders of magnitude when requiring a coincidence with the charge
readout.


title: Transfer Topic Modeling with Ease and Scalability

abstract:
  The increasing volume of short texts generated on social media sites, such as
Twitter or Facebook, creates a great demand for effective and efficient topic
modeling approaches. While latent Dirichlet allocation (LDA) can be applied, it
is not optimal due to its weakness in handling short texts with fast-changing
topics and scalability concerns. In this paper, we propose a transfer learning
approach that utilizes abundant labeled documents from other domains (such as
Yahoo! News or Wikipedia) to improve topic modeling, with better model fitting
and result interpretation. Specifically, we develop Transfer Hierarchical LDA
(thLDA) model, which incorporates the label information from other domains via
informative priors. In addition, we develop a parallel implementation of our
model for large-scale applications. We demonstrate the effectiveness of our
thLDA model on both a microblogging dataset and standard text collections
including AP and RCV1 datasets.


title: Outage Probability of Wireless Ad Hoc Networks with Cooperative Relaying

abstract:
  In this paper, we analyze the performance of cooperative transmissions in
wireless ad hoc networks with random node locations. According to a contention
probability for message transmission, each source node can either transmits its
own message signal or acts as a potential relay for others. Hence, each
destination node can potentially receive two copies of the message signal, one
from the direct link and the other from the relay link. Taking the random node
locations and interference into account, we derive closed-form expressions for
the outage probability with different combining schemes at the destination
nodes. In particular, the outage performance of optimal combining, maximum
ratio combining, and selection combining strategies are studied and quantified.


title: Topological phase in a two-dimensional metallic heavy-fermion system

abstract:
  We report on a topological insulating state in a heavy-fermion system away
from half-filling, which is hidden within a ferromagnetic metallic phase. In
this phase, the cooperation of the RKKY interaction and the Kondo effect,
together with the spin-orbit coupling, induces a spin-selective gap, bringing
about topologically non-trivial properties. This topological phase is robust
against a change in the chemical potential in a much wider range than the gap
size. We analyze these remarkable properties by using dynamical mean field
theory and the numerical renormalization group. Its topological properties
support a gapless chiral edge mode, which exhibits a non-Tomonaga-Luttinger
liquid behavior due to the coupling with bulk ferromagnetic spin fluctuations.
We also propose that the effects of the spin fluctuations on the edge mode can
be detected via the NMR relaxation time measurement.


title:
Derivation of the superconducting gap equation for the
  noncentrosymmetric superconductor Li2Pt3B

abstract:
  We present here the mathematical background of our approach, presented in
Phys. Rev. B 86, 134526 (2012) regarding the gap function and symmetry for the
noncentrosymmetric (NCS) superconductor $Li_2Pt_3B$. As revealed by the
experiment, this NCS superconductor gives rise to line nodes in the
superconducting order parameter, which is responsible for many of its
experimental behaviors. Owing to the enhanced d-character of the relevant bands
that cross the Fermi level,the system gets weakly correlated. The nature and
symmetry of this nodal behavior is explained from a microscopic viewpoint. In
this article starting with an Hubbard model relevant for this NCS system by
considering the effect of the onsite Coulomb repulsion on the pairing potential
perturbatively, we extract the superconducting gap equation. Further analysis
of this equation predicts a $s_\pm$ wave gap function with line nodes as the
most promising candidate in the superconducting state.


title:
Robust continuous-variable entanglement of microwave photons with cavity
  electromechanics

abstract:
  We investigate the controllable generation of robust photon entanglement with
a circuit cavity electromechanical system, consisting of two superconducting
coplanar waveguide cavities (CPWC's) capacitively coupled by a nanoscale
mechanical resonator (MR). We show that, with this electromechanical system,
two-mode continuous-variable entanglement of cavity photons can be engineered
deterministically either via coherent control on the dynamics of the system, or
through a dissipative quantum dynamical process. The first scheme, operating in
the strong coupling regime, explores the excitation of the cavity Bogoliubov
modes, and is insensitive to the initial thermal noise. The second one is based
on the reservoir-engineering approach, which exploits the mechanical
dissipation as a useful resource to perform ground state cooling of two
delocalized cavity Bogoliubov modes. The achieved amount of entanglement in
both schemes is determined by the relative ratio of the effective
electromechanical coupling strengths, which thus can be tuned and made much
lager than that in previous studies.


title: The Dupire derivatives and Fr\'echet derivatives on continuous pathes

abstract:
  In this paper, we study the relation between Fr\'echet derivatives and Dupire
derivatives, in which the latter are recently introduced by Dupire [4]. After
introducing the definition of Fr\'echet derivatives for non-anticipative
functionals, we prove that the Dupire derivatives and the extended Fr\'echet
derivatives are coherent on continuous pathes.


title:
A theoretical model for attachment lifetimes of
  kinetochore-microtubules: Mechano-kinetic "catch-bond" mechanism for
  error-correction

abstract:
  Before cell division, two identical copies of chromosomes are pulled apart by
microtubule (MT) filaments that approach the chromosomes from the opposite
poles a mitotic spindle. Connection between the MTs and the chromosomes are
mediated by a molecular complex called kinetochore. An externally applied
tension can lead to detachment of the MTs from the kinetochore; the mean
lifetime of such an attachment is essentially a mean first-passage time. In
their in-vitro pioneering single-kinetochore experiments, Akiyoshi et al.
(Nature 468, 576 (2010)), observed that the mean lifetimes of reconstituted
MT-kinetochore attachments vary non-monotonically with increasing tension. The
counter-intuitive stabilization of the attachments by small load forces was
interpreted in terms of a catch-bond-like mechanism based on a phenomenological
2-state kinetic model. Here we develop the first detailed microscopic model for
studying the dependence of the lifetime of the MT-kinetochore attachment on (a)
the structure, (b) energetics, and (c) kinetics of the coupling. The
catch-bond-like mechanism emerges naturally from this model. Moreover,
in-silico experiments on this model reveal further interesting phenomena,
arising from the subtle effects of competing sub-processes, which are likely to
motivate new experiments in this emerging area of single-particle biophysics.


title:
Homeomorphism and Homotopy Types of Restricted Configuration Spaces of
  Metric Graphs

abstract:
  For Gamma a finite, connected metric graph, we consider the space of
configurations of n points in Gamma with a restraint parameter r dictating the
minimum distance allowed between each pair of points. These restricted
configuration spaces come up naturally in topological robotics. In this paper,
we study the homotopy, homeomorphism, and isotopy types of these spaces over
the space of parameters r and provide a polynomial upper bound (in the number
of edges of Gamma) for the number of isotopy types.


title: Gorenstein injective precovers, covers, and envelopes

abstract:
  We give a sufficient condition for the class of Gorenstein injective modules
be precovering: if $R$ is right noetherian and if the class of Gorenstein
injective modules, $\mathcal{GI}$, is closed under filtrations, then
$\mathcal{GI}$ is precovering in $R-Mod$. The converse is also true when we
assume that $\mathcal{GI}$ is covering.
  We extend our results to the category of complexes. We prove that if the
class of Gorenstein injective modules is closed under filtrations then the
class of Gorenstein injective complexes is precovering in $Ch(R)$. We also give
a sufficient condition for the existence of Gorenstein injective covers. We
prove that if the ring $R$ is commutative noetherian and such that the
character modules of Gorenstein injective modules are Gorenstein flat, then the
class of Gorenstein injective complexes is covering. And we prove that over
such rings every complex also has a Gorenstein injective envelope. In
particular this is the case when the ring is commutative noetherian with a
dualizing complex. The second part of the paper deals with Gorenstein
projective and flat complexes. We prove that over commutative noetherian rings
of finite Krull dimension every complex of $R$-modules has a special Gorenstein
projective precover.


title:
Optimal Amplify-and-Forward Schemes for Relay Channels with Correlated
  Relay Noise

abstract:
  This paper investigates amplify-and-forward (AF) schemes for both one and
two-way relay channels. Unlike most existing works assuming independent noise
at the relays, we consider a more general scenario with correlated relay noise.
We first propose an approach to efficiently solve a class of quadratically
constrained fractional problems via second-order cone programming (SOCP). Then
it is shown that the AF relay optimization problems studied in this paper can
be incorporated into such quadratically constrained fractional problems. As a
consequence, the proposed approach can be used as a unified framework to solve
the optimal AF rate for the one-way relay channel and the optimal AF rate
region for the two-way relay channel under both sum and individual relay power
constraints.
  In particular, for one-way relay channel under individual relay power
constraints, we propose two suboptimal AF schemes in closed-form. It is shown
that they are approximately optimal in certain conditions of interest.
Furthermore, we find an interesting result that, on average, noise correlation
is beneficial no matter the relays know the noise covariance matrix or not for
such scenario. Overall, the obtained results recover and generalize several
existing results for the uncorrelated counterpart. (unsubmitted)


title: Acceleration in Weyl integrable spacetime

abstract:
  We study homogeneous and isotropic cosmologies in a Weyl spacetime. It is
shown that in Weyl integrable spacetime, the corresponding scalar field may act
as a phantom field. In this circumstance the Weyl field gives rise to a late
accelerated expansion of the Universe for all initial conditions and for a wide
range of the parameters.


title: Rainbow C_4's and Directed C_4's: the Bipartite Case Study

abstract:
  In this paper we obtain a new sufficient condition for the existence of
directed cycles of length 4 in oriented bipartite graphs. As a corollary, a
conjecture of H. Li is confirmed. As an application, a sufficient condition for
the existence of rainbow cycles of length 4 in bipartite edge-colored graphs is
obtained.


title:
Dissipation-driven two-mode mechanical squeezed states in optomechanical
  systems

abstract:
  In this paper, we propose two quantum optomechanical arrangements that permit
the dissipation-enabled generation of steady two-mode mechanical squeezed
states. In the first setup, the mechanical oscillators are placed in a two-mode
optical resonator while in the second setup the mechanical oscillators are
located in two coupled single-mode cavities. We show analytically that for an
appropriate choice of the pump parameters, the two mechanical oscillators can
be driven by cavity dissipation into a stationary two-mode squeezed vacuum,
provided that mechanical damping is negligible. The effect of thermal
fluctuations is also investigated in detail and show that ground state
pre-cooling of the oscillators in not necessary for the two-mode squeezing.
These proposals can be realized in a number of optomechanical systems with
current state-of-the-art experimental techniques.


title: A Single Field Inflation Model with Large Local Non-Gaussianity

abstract:
  A detection of large local form non-Gaussianity is considered to be able to
rule out all single field inflation models. This statement is based on a single
field consistency condition. Despite the awareness of some implicit assumptions
in the derivation of this condition and the demonstration of corresponding
examples that illustrate these caveats, to date there is still no explicit and
self-consistent model which can serve as a counterexample to this statement. We
present such a model in this Letter.


title: Kinetic Theory of the Presheath and the Bohm Criterion

abstract:
  A kinetic theory of the Bohm criterion is developed that is based on
positive-exponent velocity moments of the plasma kinetic equation. This result
is contrasted with the conventional kinetic Bohm criterion that is based on a
v^{-1} moment of the Vlasov equation. The salient difference between the two
results is that low velocity particles dominate in the conventional theory, but
are essentially unimportant in the new theory. It is shown that the derivation
of the conventional kinetic Bohm criterion is flawed. Low velocity particles
can cause unphysical divergences in the conventional theory. These divergent
contributions are avoided with this new approach. The two theories are compared
using example distribution functions from previous presheath models. The
importance of ion-ion and electron-electron collisions to determining the
particle distribution functions throughout the presheath is also discussed. A
kinetic equation that accounts for wave-particle scattering by convective
instabilities is used to show that ion-acoustic instabilities in the presheath
of low temperature plasmas (where T_e \gg T_i) can cause both ions and
electrons to obtain Maxwellian distribution functions near the sheath.


title:
Sequential and Decentralized Estimation of Linear Regression Parameters
  in Wireless Sensor Networks

abstract:
  Sequential estimation of a vector of linear regression coefficients is
considered under both centralized and decentralized setups. In sequential
estimation, the number of observations used for estimation is determined by the
observed samples, hence is random, as opposed to fixed-sample-size estimation.
Specifically, after receiving a new sample, if a target accuracy level is
reached, we stop and estimate using the samples collected so far; otherwise we
continue to receive another sample. It is known that finding an optimum
sequential estimator, which minimizes the average sample number for a given
target accuracy level, is an intractable problem with a general stopping rule
that depends on the complete observation history. By properly restricting the
search space to stopping rules that depend on a specific subset of the complete
observation history, we derive the optimum sequential estimator in the
centralized case via optimal stopping theory. However, finding the optimum
stopping rule in this case requires numerical computations that {\em
quadratically} scales with the number of parameters to be estimated. For the
decentralized setup with stringent energy constraints, under an alternative
problem formulation that is conditional on the observed regressors, we first
derive a simple optimum scheme whose computational complexity is {\em constant}
with respect to the number of parameters. Then, following this simple optimum
scheme we propose a decentralized sequential estimator whose computational
complexity and energy consumption scales {\em linearly} with the number of
parameters. Specifically, in the proposed decentralized scheme a
close-to-optimum average stopping time performance is achieved by infrequently
transmitting a single pulse with very short duration.

categories: stat.AP cs.IT math.IT math.OC math.PR stat.ME


title: Low-lying zeroes of Maass form $L$-functions

abstract:
  The Katz-Sarnak density conjecture states that the scaling limits of the
distributions of zeros of families of automorphic $L$-functions agree with the
scaling limits of eigenvalue distributions of classical subgroups of the
unitary groups $U(N)$. This conjecture is often tested by way of computing
particular statistics, such as the one-level density, which evaluates a test
function with compactly supported Fourier transform at normalized zeros near
the central point. Iwaniec, Luo, and Sarnak studied the one-level densities of
cuspidal newforms of weight $k$ and level $N$. They showed in the limit as $kN
\to\infty$ that these families have one-level densities agreeing with
orthogonal type for test functions with Fourier transform supported in
$(-2,2)$. Exceeding $(-1,1)$ is important as the three orthogonal groups are
indistinguishable for support up to $(-1,1)$ but are distinguishable for any
larger support. We study the other family of ${\rm GL}_2$ automorphic forms
over $\mathbb{Q}$: Maass forms. To facilitate the analysis, we use smooth
weight functions in the Kuznetsov formula which, among other restrictions,
vanish to order $M$ at the origin. For test functions with Fourier transform
supported inside $\left(-2 + \frac{2}{2M+1}, 2 - \frac{2}{2M+1}\right)$, we
unconditionally prove the one-level density of the low-lying zeros of level 1
Maass forms, as the eigenvalues tend to infinity, agrees only with that of the
scaling limit of orthogonal matrices.


title: When Generalized Sumsets are Difference Dominated

abstract:
  We study the relationship between the number of minus signs in a generalized
sumset, $A+...+A-...-A$, and its cardinality; without loss of generality we may
assume there are at least as many positive signs as negative signs. As addition
is commutative and subtraction is not, we expect that for most $A$ a
combination with more minus signs has more elements than one with fewer;
however, recently Iyer, Lazarev, Miller and Zhang proved that a positive
percentage of the time the combination with fewer minus signs can have more
elements. Their analysis involves choosing sets $A$ uniformly at random from
${0,...,N}$; this is equivalent to independently choosing each element of
${0,...,N}$ to be in $A$ with probability 1/2. We investigate what happens when
instead each element is chosen with probability $p(N)$, with $\lim_{N\to\infty}
p(N) =0$. We prove that the set with more minus signs is larger with
probability 1 as $N\to\infty$ if $p(N)=cN^{-\delta}$ for
$\delta\ge\frac{h-1}{h}$, where $h$ is the number of total summands in
$A+...+A-...-A$, and explicitly quantify their relative sizes. The results
generalize earlier work of Hegarty and Miller, and we see a phase transition in
the behavior of the cardinalities when $\delta = \frac{h-1}{h}$.


title: The coevent formulation of quantum theory

abstract:
  Understanding quantum theory has been a subject of debate from its birth.
Many different formulations and interpretations have been proposed. Here we
examine a recent novel formulation, namely the coevents formulation. It is a
histories formulation and has as starting point the Feynman path integral and
the decoherence functional. The new ontology turns out to be that of a
coarse-grained history. We start with a quantum measure defined on the space of
histories, and the existence of zero covers rules out single-history as
potential reality (the Kochen Specker theorem casted in histories form is a
special case of a zero cover). We see that allowing coarse-grained histories as
potential realities avoids the previous paradoxes, maintains deductive
non-contextual logic (alas non-Boolean) and gives rise to a unique classical
domain. Moreover, we can recover the probabilistic predictions of quantum
theory with the use of the Cournot's principle. This formulation, being both a
realist formulation and based on histories, is well suited conceptually for the
purposes of quantum gravity and cosmology.


title:
Orthogonal Dirac semimetal on honeycomb lattice and the electron
  spectral function in orthogonal metallic states

abstract:
  Recently, a concept of orthogonal metal has been introduced to reinterpret
the disordered state of slave-spin representation in the Hubbard model as an
exotic gapped metallic state. We have extended this concept to study the
slave-spin representation of Hubbard model on the honeycomb lattice.[Phys. Rev.
B \textbf{86}, 165134 (2012)] It is found that a novel gapped metallic state
coined orthogonal Dirac semimetal is identified. Such state corresponds to the
disordered phase of slave-spin and has the same thermal-dynamical and transport
properties as Dirac semimetal but its singe-particle excitation is gapped. More
importantly, for generical orthogonal metallic states, the electron spectral
function which may be probed in future angle-resolved photoemission
spectroscopy (ARPES) experiments are studied.


title: Post-Newtonian Celestial Dynamics in Cosmology: Field Equations

abstract:
  The present paper outlines theoretical principles of the post-Newtonian
mechanics in the expanding universe. It is based upon the gauge-invariant
theory of the Lagrangian perturbations of cosmological manifold caused by an
isolated astronomical N-body system. We postulate that the background manifold
is described by Friedman-Lemaitre-Robertson-Walker (FLRW) metric governed by
two primary components - the dark matter and the dark energy. The dark matter
is treated as an ideal fluid. The dark energy is described by a single scalar
field with a potential which is hold unspecified as long as the theory permits.
The Lagrangian of the dark matter and that of the scalar field are formulated
in terms of the field variables. We use variational calculus to derive the
gauge-invariant field equations of the post-Newtonian celestial mechanics of an
isolated astronomical system in an expanding universe. These equations
generalize the field equations of the post-Newtonian theory in
asymptotically-flat spacetime by taking into account the cosmological effects
explicitly. We introduce a new cosmological gauge which generalizes the
harmonic gauge of the post-Newtonian theory in asymptotically-flat spacetime.
This gauge significantly simplifies the gravitational field equations and
allows finding out the approximations where the field equations can be fully
decoupled and solved analytically. The residual gauge freedom is explored. The
results of the present paper can be useful in the solar system for calculating
more precise ephemerides of the solar system bodies on extremely long time
intervals, in galactic astronomy to study the dynamics of clusters of galaxies,
and in gravitational wave astronomy for discussing the impact of cosmology on
generation and propagation of gravitational waves emitted by coalescing
binaries and/or merging galactic nuclei.


title:
Width of photon decay in magnetic field: elementary semiclassical
  derivation and sensitivity to Lorentz violation

abstract:
  We present an elementary derivation of the width of photon decay in a weak
magnetic field using the semiclassical method of worldline instantons. The
calculation is generalized to a model of quantum electrodynamics with broken
Lorentz symmetry. Implications for the search of deviations from Lorentz
invariance in the cosmic ray experiments are discussed.


title: Pressure effects in hollow and solid iron oxide nanoparticles

abstract:
  We report a study on the pressure response of the anisotropy energy of hollow
and solid maghemite nanoparticles. The differences between the maghemite
samples are understood in terms of size, magnetic anisotropy and shape of the
particles. In particular, the differences between hollow and solid samples are
due to the different shape of the nanoparticles and by comparing both pressure
responses it is possible to conclude that the shell has a larger pressure
response when compared to the core.


title:
Mesoscopic Transport of Entangled and Nonentangled Kondo Singlets under
  Bias

abstract:
  The tunneling conductances of a quantum point contact and a magnetized atom
adsorbed on an insulating layer above a metallic substrate are obtained by
considering the coherent transport of the entangled and nonentangled Kondo
singlets, and these are compared with the experimental results. Spins of the
entangled Kondo singlet flow unidirectionally in a sequential up-and-down
manner. This transport does not follow linear response theory. The nonentangled
Kondo singlet performs resonant tunneling through a coherent transport channel
and yields coherent side peaks at a finite bias. The coherent transport channel
is formed by two electron reservoirs within a coherent region.


title:
Characteristics Analysis and State Transfer for non-Markovian Open
  Quantum Systems

abstract:
  The weak-coupled two-level open quantum system described by non-Markovian
Time-convolution-less master equation is investigated in this paper. The
cut-off frequency, coupling constant and transition frequency, which impact on
the system's decay rate, coherence factor and purity, are investigated. The
appropriate parameters used in system simulation experiments are determined by
comparing analysis results of different values of parameters for the effects of
system performance. The control laws used to transfer the system states are
designed on the basis of the Lyapunov stability theorem. Numerical simulation
experiments are implemented under the MATLAB environment. The features of the
free evolution trajectory of the non-Markovian systems and the states transfer
from a pure state to a desired pure state under the action of the proposed
control laws are studied, respectively. By comparing the experimental results,
the effectiveness of the proposed quantum Lyapunov control method applied to
the state transfer in non-Markovian open quantum systems is verified.
Meanwhile, the influences of different control parameters and cut-off
frequencies on the system performance are analyzed.


title: Computing Intrinsic Lyman-alpha Fluxes of F5 V to M5 V Stars

abstract:
  The Lyman-alpha emission line dominates the far-ultraviolet spectra of
late-type stars and is a major source for photodissociation of important
molecules including H2O, CH4, and CO2 in exoplanet atmospheres. The incident
flux in this line illuminating an exoplanet's atmosphere cannot be measured
directly as neutral hydrogen in the interstellar medium (ISM) attenuates most
of the flux reaching the Earth. Reconstruction of the intrinsic Lyman-alpha
line has been accomplished for a limited number of nearby stars, but is not
feasible for distant or faint host stars. We identify correlations connecting
the intrinsic Lyman-alpha flux with the flux in other emission lines formed in
the stellar chromosphere, and find that these correlations depend only
gradually on the flux in the other lines. These correlations, which are based
on HST spectra, reconstructed Lyman-alpha line fluxes, and irradiance spectra
of the quiet and active Sun, are required for photochemical models of exoplanet
atmospheres when intrinsic Lyman-alpha fluxes are not available. We find a
tight correlation of the intrinsic Lyman-alpha flux with stellar X-ray flux for
F5 V to K5 V stars, but much larger dispersion for M stars. We also show that
knowledge of the stellar effective temperature and rotation rate can provide
reasonably accurate estimates of the Lyman-alpha flux for G and K stars, and
less accurate estimates for cooler stars.


title:
Anomalous localized resonance using a folded geometry in three
  dimensions

abstract:
  If a body of dielectric material is coated by a plasmonic structure of
negative dielectric material with nonzero loss parameter, then cloaking by
anomalous localized resonance (CALR) may occur as the loss parameter tends to
zero. It was proved in other papers by authors that if the coated structure is
circular (2D) and dielectric constant of the shell is a negative constant (with
loss parameter), then CALR occurs, and if the coated structure is spherical
(3D), then CALR does not occur. The aim of this paper is to show that the CALR
takes place if the spherical coated structure has a specially designed
anisotropic dielectric tensor. The anisotropic dielectric tensor is designed by
unfolding a folded geometry.


title:
Some aspects of fluctuations of random walks on R and applications to
  random walks on R+ with non-elastic reflection at 0

abstract:
  In this article we refine well-known results concerning the fluctuations of
one-dimensional random walks. More precisely, if $(S_n)_{n \geq 0}$ is a random
walk starting from 0 and $r\geq 0$, we obtain the precise asymptotic behavior
as $n\to\infty$ of $\mathbb P[\tau^{>r}=n, S_n\in K]$ and $\mathbb
P[\tau^{>r}>n, S_n\in K]$, where $\tau^{>r}$ is the first time that the random
walk reaches the set $]r,\infty[$, and $K$ is a compact set. Our assumptions on
the jumps of the random walks are optimal. Our results give an answer to a
question of Lalley stated in [9], and are applied to obtain the asymptotic
behavior of the return probabilities for random walks on $\mathbb R^+$ with
non-elastic reflection at 0.


title:
Entropic inequalities as a necessary and sufficient condition to
  noncontextuality and locality

abstract:
  The assumption of local realism in a Bell locality scenario imposes
non-trivial conditions on the Shannon entropies of the associated probability
distributions, expressed by linear entropic Bell inequalities. In principle,
these entropic inequalities provide necessary but not sufficient criteria for
the existence of a local hidden variable model reproducing the correlations,
as, for example, the paradigmatic nonlocal PR-box is entropically not different
from a classically correlated box. In this paper we show that for the n-cycle
scenario, entropic inequalities completely characterize the set of local
correlations. In particular, every nonsignalling box which violates the CHSH
inequality -- including the PR-box -- can be locally modified so that it also
violates the entropic version of CHSH inequality. As we show, any nonlocal
probabilistic model when appropriately mixed with a local model, violates an
entropic inequality, thus evidencing a very peculiar kind of nonlocality. As
the n-cycle captures equally well both the notion of local realism introduced
by Bell and that of noncontextuality presented by the Kochen-Specker theorem,
the results are also valid for noncontextuality scenarios.


title: The covariation for Banach space valued processes and applications

abstract:
  This article focuses on a new concept of quadratic variation for processes
taking values in a Banach space $B$ and a corresponding covariation. This is
more general than the classical one of M\'etivier and Pellaumail. Those notions
are associated with some subspace $\chi$ of the dual of the projective tensor
product of $B$ with itself. We also introduce the notion of a convolution type
process, which is a natural generalization of the It\^o process and the concept
of $\bar \nu_0$-semimartingale, which is a natural extension of the classical
notion of semimartingale. The framework is the stochastic calculus via
regularization in Banach spaces. Two main applications are mentioned: one
related to Clark-Ocone formula for finite quadratic variation processes; the
second one concerns the probabilistic representation of a Hilbert valued
partial differential equation of Kolmogorov type.


title:
Random walks in the quarter plane, discrete harmonic functions and
  conformal mappings

abstract:
  We propose a new approach for finding discrete harmonic functions in the
quarter plane with Dirichlet conditions. It is based on solving functional
equations that are satisfied by the generating functions of the values taken by
the harmonic functions. As a first application of our results, we obtain a
simple expression for the harmonic function that governs the asymptotic tail
distribution of the first exit time for random walks from the quarter plane. As
another corollary, we prove, in the zero drift case, the uniqueness of the
discrete harmonic function.


title: Luminosity Evolution of Gamma-ray Pulsars

abstract:
  We investigate the electrodynamic structure of a pulsar outer-magnetospheric
particle accelerator and the resultant gamma-ray emission. By considering the
condition for the accelerator to be self-sustained, we derive how the
trans-magnetic-field thickness of the accelerator evolves with the pulsar age.
It is found that the thickness is small but increases steadily if the
neutron-star envelope is contaminated by sufficient light elements. For such a
light element envelope, the gamma-ray luminosity of the accelerator is kept
approximately constant as a function of age in the initial ten thousand years,
forming the lower bound of the observed distribution of the gamma-ray
luminosity of rotation-powered pulsars. If the envelope consists of only heavy
elements, on the other hand, the thickness is greater but increases less
rapidly than what a light element envelope has. For such a heavy element
envelope, the gamma-ray luminosity decreases relatively rapidly, forming the
upper bound of the observed distribution. The gamma-ray luminosity of a general
pulsar resides between these two extreme cases, reflecting the envelope
composition and the magnetic inclination angle with respect to the rotation
axis. The cutoff energy of the primary curvature emission is regulated below
several GeV even for young pulsars, because the gap thickness, and hence the
acceleration electric field is suppressed by the polarization of the produced
pairs.


title: Domain theory and mirror properties in inverse semigroups

abstract:
  Inverse semigroups are a class of semigroups whose structure induces a
compatible partial order. This partial order is examined so as to establish
mirror properties between an inverse semigroup and the semilattice of its
idempotent elements, such as continuity in the sense of domain theory.


title: Realization of higher Wess-Zumino-Witten models in spin chains

abstract:
  Building on the generalization of the exactly dimerized Majumdar-Ghosh ground
state to arbitrary spin S for the Heisenberg chain with a three-site term
(S_{i-1} S_i)(S_i S_{i+1}) + H.c., we use density-matrix renormalization group
simulations and exact diagonalizations to determine the nature of the
dimerization transition for S=1, 3/2 and 2. The resulting central charge and
critical exponent are in good agreement with the SU(2)_{k=2S}
Wess-Zumino-Witten values c=3k/(2+k) and \eta=3/(2+k). Since the 3-site term
that induces dimerization appears naturally if exchange interactions are
calculated beyond second order, these results suggest that SU(2)_{k>1}
Wess-Zumino-Witten models might finally be realized in actual spin chains.


title: New further integrability cases for the Riccati equation

abstract:
  New further integrability conditions of the Riccati equation
$dy/dx=a(x)+b(x)y+c(x)y^{2}$ are presented. The first case corresponds to fixed
functional forms of the coefficients $a(x)$ and $c(x)$ of the Riccati equation,
and of the function $F(x)=a(x)+[f(x)-b^{2}(x)]/4c(x)$, where $f(x)$ is an
arbitrary function. The second integrability case is obtained for the "reduced"
Riccati equation with $b(x)\equiv 0$. If the coefficients $a(x)$ and $c(x)$
satisfy the condition $\pm d\sqrt{f(x)/c(x)}/dx=a(x)+f(x)$, where $f(x)$ is an
arbitrary function, then the general solution of the "reduced" Riccati equation
can be obtained by quadratures. The applications of the integrability condition
of the "reduced" Riccati equation for the integration of the Schr\"odinger and
Navier-Stokes equations are briefly discussed.


title:
Shapes of primordial non-Gaussianities in the Horndeski's most general
  scalar-tensor theories

abstract:
  In the Horndeski's most general scalar-tensor theories, we derive the
three-point correlation function of scalar non-Gaussianities generated during
single-field inflation in the presence of slow-variation corrections to the
leading-order term. Unlike previous works, the resulting bispectrum is valid
for any shape of non-Gaussianities. In the squeezed limit, for example, this
gives rise to the same consistency relation as that derived by Maldacena in
standard single-field slow-roll inflation. We estimate the shape close to the
squeezed one at which the effect of the term inversely proportional to the
scalar propagation speed squared begins to contribute to the bispectrum. We
also show that the leading-order bispectrum can be expressed by the linear
combination of two convenient bases whose shapes are highly correlated with
equilateral and orthogonal types respectively. We present concrete models in
which the orthogonal and enfolded shapes can dominate over the equilateral one.


title:
Asymptotically Optimal Detection of Changes in Stochastic Models with
  Switching Regimes

abstract:
  This paper deals with the problem of asymptotically optimal detection of
changes in regime-switching stochastic models. We need to divide the whole
obtained sample of data into several sub-samples with observations belonging to
different states of a stochastic models with switching regimes. For this
purpose, the idea of reduction to a corresponding change-point detection
problem is used. Both univariate and multivariate switching models are
considered. For the univariate case, we begin with the study of binary mixtures
of probabilistic distributions. In theorems 1 and 2 we prove that type 1 and
type 2 errors of the proposed method converge to zero exponentially as the
sample size tends to infinity. In theorem 3 we prove that the proposed method
is asymptotically optimal by the rate of this convergence in the sense that the
lower bound in the a priori informational inequality is attained for our
method. Several generalizations to the case of multiple univariate mixtures of
probabilistic distributions are considered. For the multivariate case, we first
study the general problem of classification of the whole array of data into
several sub-arrays of observations from different regimes of a multivariate
stochastic model with switching states. Then we consider regression models with
abnormal observations and switching sets of regression coefficients. Results of
a detailed Monte Carlo study of the proposed method for different stochastic
models with switching regimes are presented.


title: Sorting and generating reduced words

abstract:
  We introduce a partial order on the set of all reduced words of a given
permutation $\omega$, called \emph{directed-braid poset} of $\omega$. This
poset enables us to produce two algorithms: One is a sorting algorithm applied
on any reduced word of $\omega$ and aims to obtained the natural word
(lexicographically largest reduced word); the other one is a generation
algorithm applied on the natural word and aims to obtained the set of all
reduced words of $\omega$.


title: On classification of measurable functions of several variables

abstract:
  We define a normal form (called the canonical image) of an arbitrary
measurable function of several variables with respect to a natural group of
transformations; describe a new complete system of invariants of such a
function (the system of joint distributions); and relate these notions to the
matrix distribution, another invariant of measurable functions found earlier,
which is a random matrix. Bibliography: 7 titles.


title:
Evolution of cross-correlation and time lag of 4U 1735-44 along the
  branches

abstract:
  We analyze the cross-correlation function between the soft and hard X-rays of
atoll source 4U 1735-44 with RXTE data, and find the anti-correlated soft and
hard time lags of about hecto-second. On the island state, the observations do
not show any obvious correlations, and most observations of banana branch show
positive correlation. However, the anti-correlations are detected on the upper
banana branch. These results are different from those of Z sources (Cyg X-2, GX
5-1), where the anti-correlation is detected in the low luminosity states, then
the lag timescales of both this atoll and Z sources are found to be similar, at
the magnitude of several tens to hundreds of seconds. As a comparison, it is
noted that the anti-correlated lags of thousand-second have been reported from
the several black hole candidates in their intermediate states. Finally, we
compare the correspondent results of atoll source 4U 1735-44 with those
observed in black hole candidates and Z sources, and the possible origins of
the anti-correlated time lags are discussed.


title:
Some classes of weighted conditional expectation type operators on
  $l^2(\sigma)

abstract:
  In this paper, some various partial normality classes of weighted conditional
expectation type operators on L2() are investigated. Also, some applications of
weak hyponormal weighted conditional type operators are pre- sented.


title: Fixed point of subadditive maps and some non-linear integral equations

abstract:
  In this paper, first some results of [5] are extended for subadditive
separating maps between C(X;E) and C(Y;E), such that E is a unital Banach
algebra. Then we give some conditions under which a strongly subadditive map
has a unique fixed point. Finally as an application the existence and
uniqueness of solution for a nonlinear integral equation is discussed.


title:
A Potential Theory of General Spatially-Coupled Systems via a Continuum
  Approximation

abstract:
  This paper analyzes general spatially-coupled (SC) systems with
multi-dimensional coupling. A continuum approximation is used to derive
potential functions that characterize the performance of the SC systems. For
any dimension of coupling, it is shown that, if the boundary of the SC systems
is fixed to the unique stable solution that minimizes the potential over all
stationary solutions, the systems can approach the optimal performance as the
number of coupled systems tends to infinity.


title: Left-orderable, non-L-space surgeries on knots

abstract:
  Let K be a knot in the 3--sphere. An r-surgery on K is left-orderable if the
resulting 3--manifold K(r) of the surgery has left-orderable fundamental group,
and an r-surgery on K is called an L-space surgery if K(r) is an L-space. A
conjecture of Boyer, Gordon and Watson says that non-reducing surgeries on K
can be classified into left-orderable surgeries or L-space surgeries. We
introduce a way to provide knots with left-orderable, non-L-space surgeries. As
an application we present infinitely many hyperbolic knots on each of which
every nontrivial surgery is a hyperbolic, left-orderable, non-L-space surgery.


title: Pulsar Timing Arrays

abstract:
  In the last decade, the use of an ensemble of radio pulsars to constrain the
characteristic strain caused by a stochastic gravitational wave background has
advanced the cause of detection of very low frequency gravitational waves
significantly. This electromagnetic means of gravitational wave detection,
called Pulsar Timing Array(PTA), is reviewed in this article. The principle of
operation of PTA, the current operating PTAs and their status is presented
along-with a discussion of the main challenges in the detection of
gravitational waves using PTA.


title:
First-principles model potentials for lattice-dynamical studies: general
  methodology and example of application to ferroic perovskite oxides

abstract:
  We present a scheme to construct model potentials, with parameters computed
from first principles, for large-scale lattice-dynamical simulations of
materials. Our method mimics the traditional solid-state approach to the
investigation of vibrational spectra, i.e., we start from a suitably chosen
reference configuration of the material and describe its energy as a function
of arbitrary atomic distortions by means of a Taylor series. Such a form of the
potential-energy surface is completely general, trivial to formulate for any
compound, and physically transparent. Further, the approximations involved in
our effective models are clear-cut, and the precision can be improved in a
systematic and well-defined fashion. Moreover, such a simple definition allows
for a straightforward determination of the parameters in the low-order terms of
the series, as they are the direct result of
density-functional-perturbation-theory calculations, which greatly simplifies
the model construction. Here we present such a scheme, discuss a practical and
versatile methodology for the calculation of the model parameters from first
principles, and describe our results for two challenging cases in which the
model potential is strongly anharmonic, namely, ferroic perovskite oxides
PbTiO3 and SrTiO3. The choice of test materials was partly motivated by
historical reasons, since our scheme can be viewed as a natural extension of
(and was initially inspired by) the so-called first-principles effective
Hamiltonian approach to the investigation of temperature-driven effects in
ferroelectric perovskite oxides. Thus, the study of these compounds allows us
to better describe the connections between the effective-Hamiltonian method and
ours.


title: Third- and fourth-order elasticity of biological soft tissues

abstract:
  In the theory of weakly non-linear elasticity, Hamilton et al. [J. Acoust.
Soc. Am. \textbf{116} (2004) 41] identified $W = \mu I_2 + (A/3)I_3 + D I_2^2$
as the fourth-order expansion of the strain-energy density for incompressible
isotropic solids. Subsequently, much effort focused on theoretical and
experimental developments linked to this expression in order to inform the
modeling of gels and soft biological tissues. However, while many soft tissues
can be treated as incompressible, they are not in general isotropic, and their
anisotropy is associated with the presence of oriented collagen fiber bundles.
Here the expansion of $W$ is carried up to fourth-order in the case where there
exists one family of parallel fibers in the tissue. The results are then
applied to acoustoelasticity, with a view to determining the second- and
third-order nonlinear constants by employing small-amplitude transverse waves
propagating in a deformed soft tissue.


title: Quantum metrology with open dynamical systems

abstract:
  This paper studies quantum limits to dynamical sensors in the presence of
decoherence. A modified purification approach is used to obtain tighter quantum
detection and estimation error bounds for optical phase sensing and
optomechanical force sensing. When optical loss is present, these bounds are
found to obey shot-noise scalings for arbitrary quantum states of light under
certain realistic conditions, thus ruling out the possibility of asymptotic
Heisenberg error scalings with respect to the average photon flux under those
conditions. The proposed bounds are expected to be approachable using current
quantum optics technology.


title:
Reinforcement learning from comparisons: Three alternatives is enough,
  two is not

abstract:
  The paper deals with the problem of finding the best alternatives on the
basis of pairwise comparisons when these comparisons need not be transitive. In
this setting, we study a reinforcement urn model. We prove convergence to the
optimal solution when reinforcement of a winning alternative occurs each time
after considering three random alternatives. The simpler process, which
reinforces the winner of a random pair does not always converges: it may cycle.


title:
Mode Decomposition Methods for Flows in High-Contrast Porous Media. Part
  I. Global Approach

abstract:
  We apply dynamic mode decomposition (DMD) and proper orthogonal decomposition
(POD) methods to flows in highly-heterogeneous porous media to extract the
dominant coherent structures and derive reduced-order models via Galerkin
projection. Permeability fields with high contrast are considered to
investigate the capability of these techniques to capture the main flow
features and forecast the flow evolution within a certain accuracy. A DMD-based
approach shows a better predictive capability due to its ability to accurately
extract the information relevant to long-time dynamics, in particular, the
slowly-decaying eigenmodes corresponding to largest eigenvalues. Our study
enables a better understanding of the strengths and weaknesses of the
applicability of these techniques for flows in high-contrast porous media.
Furthermore, we discuss the robustness of DMD- and POD-based reduced-order
models with respect to variations in initial conditions, permeability fields,
and forcing terms.


title: Gevrey local solvability in locally integrable structures

abstract:
  We consider a locally integrable real-analytic structure, and we investigate
the local solvability in the category of Gevrey functions and
ultradistributions of the complex d' naturally induced by the de Rham complex.
We prove that the so-called condition Y(q) on the signature of the Levi form,
for local solvability of d' u=f, is still necessary even if we take f in the
classes of Gevrey functions and look for solutions u in the corresponding
spaces of ultradistributions.


title: Normal states of type III factors

abstract:
  Let M be a factor of type III with separable predual and with normal states
phi_1,...,phi_k, omega with omega faithful. Let A be a finite dimensional
C*-subalgebra of M. Then it is shown that there is a unitary operator u in M
such that phi_i Ad u =omega on A for i=1,...,k. This follows from an embedding
result of a finite dimensional C*-algebra with a faithful state into M with
finitely many given states. We also give similar embedding results of
C*-algebras and von Neumann algebras with faithful states into M. Another
similar result for a factor of type II_1 instead of type III holds.


title: Best Response Games on Regular Graphs

abstract:
  With the growth of the internet it is becoming increasingly important to
understand how the behaviour of players is affected by the topology of the
network interconnecting them. Many models which involve networks of interacting
players have been proposed and best response games are amongst the simplest. In
best response games each vertex simultaneously updates to employ the best
response to their current surroundings. We concentrate upon trying to
understand the dynamics of best response games on regular graphs with many
strategies. When more than two strategies are present highly complex dynamics
can ensue. We focus upon trying to understand exactly how best response games
on regular graphs sample from the space of possible cellular automata. To
understand this issue we investigate convex divisions in high dimensional space
and we prove that almost every division of $k-1$ dimensional space into $k$
convex regions includes a single point where all regions meet. We then find
connections between the convex geometry of best response games and the theory
of alternating circuits on graphs. Exploiting these unexpected connections
allows us to gain an interesting answer to our question of when cellular
automata are best response games.


title: Spin physics at A Fixed-Target ExpeRiment at the LHC (AFTER@LHC)

abstract:
  We outline the opportunities for spin physics which are offered by a next
generation and multi-purpose fixed-target experiment exploiting the proton LHC
beam extracted by a bent crystal. In particular, we focus on the study of
single transverse spin asymetries with the polarisation of the target.


title: Ghost numbers of Group Algebras

abstract:
  Motivated by Freyd's famous unsolved problem in stable homotopy theory, the
generating hypothesis for the stable module category of a finite group is the
statement that if a map in the thick subcategory generated by the trivial
representation induces the zero map in Tate cohomology, then it is stably
trivial. It is known that the generating hypothesis fails for most groups.
Generalizing work done for $p$-groups, we define the ghost number of a group
algebra, which is a natural number that measures the degree to which the
generating hypothesis fails. We describe a close relationship between ghost
numbers and Auslander-Reiten triangles, with many results stated for a general
projective class in a general triangulated category. We then compute ghost
numbers and bounds on ghost numbers for many families of $p$-groups, including
abelian $p$-groups, the quaternion group and dihedral $2$-groups, and also give
a general lower bound in terms of the radical length, the first general lower
bound that we are aware of. We conclude with a classification of group algebras
of $p$-groups with small ghost number and examples of gaps in the possible
ghost numbers of such group algebras.


title: Lambda(1405) poles obtained from pi0-Sigma0 photoproduction data

abstract:
  We present a strategy to extract the position of the two $\Lambda(1405)$
poles from experimental photoproduction data measured recently at different
energies in the $\gamma p \to K^+ \pi^0 \Sigma^0 $ reaction at Jefferson Lab.
By means of a chiral dynamics motivated potential but with free parameters, we
solve the Bethe Salpeter equation in the coupled channels $\bar K N$ and $\pi
\Sigma$ in isospin I=0 and parameterize the amplitude for the photonuclear
reaction in terms of a linear combination of the $\pi \Sigma \to \pi \Sigma$
and $\bar K N \to \pi \Sigma$ scattering amplitudes in I=0, with a different
linear combination for each energy. Good fits to the data are obtained with
some sets of parameters, by means of which one can also predict the cross
section for the $K^- p \to \pi^0 \Sigma^0 $ reaction. These later results help
us decide among the possible solutions. The result is that the different
solutions lead to two poles similar to those found in the chiral unitary
approach. With the best result we find the two $\Lambda(1405)$ poles at
$1385-68i\mev$and $1419-22i\mev$.


title:
Mode Decomposition Methods for Flows in High-Contrast Porous Media. Part
  II. Local-Global Approach

abstract:
  In this paper, we combine concepts of the generalized multiscale finite
element method and mode decomposition methods to construct a robust
local-global approach for model reduction of flows in high-contrast porous
media. This is achieved by implementing proper orthogonal decomposition (POD)
and dynamic mode decomposition (DMD) techniques on a coarse grid. The resulting
reduced-order approach enables a significant reduction in the flow problem size
while accurately capturing the behavior of fully resolved solutions. We
consider a variety of high-contrast coefficients and present the corresponding
numerical results to illustrate the effectiveness of the proposed technique.
This paper is a continuation of the first part where we examine the
applicability of POD and DMD to derive simplified and reliable representations
of flows in high-contrast porous media. In the current paper, we discuss how
these global model reduction approaches can be combined with local techniques
to speed-up the simulations. The speed-up is due to inexpensive, while
sufficiently accurate, computations of global snapshots.


title: Engineering Polarization Rotation in Ferroelectric Bismuth Titanate

abstract:
  Here, we report a combined experimental-theoretical study showing that
collective application of rare earth doping on A-site and epitaxial strain to
ferroelectric bismuth titanate does not lead to a very large c-axis
polarization as reported previously. Further first principles calculations
based on the examination of polarization tensor suggest that simultaneous Bi
and Ti site doping could result in moderate polarization along c-axis of
bismuth titanate which is typically a preferential axis of film growth and thus
enabling c axis oriented films to have appreciable polarization. This approach
could also be applicable to other ferroic oxides where one can correlate the
doping, epitaxial strain, and polarization to design materials compositions
resulting in epitaxial films grown along desired directions yielding
substantial polarization.


title: Rapid stabilization in a semigroup framework

abstract:
  We prove the well-posedness of a linear closed-loop system with an explicit
(already known) feedback leading to arbitrarily large decay rates. We define a
mild solution of the closed-loop problem using a dual equation and we prove
that the original operator perturbed by the feedback is (up to the use of an
extension) the infinitesimal generator of a strongly continuous group. We also
give a justification to the exponential decay of the solutions. Our method is
direct and avoids the use of optimal control theory.


title: Central sets and substitutive dynamical systems

abstract:
  In this paper we establish a new connection between central sets and the
strong coincidence conjecture for fixed points of irreducible primitive
substitutions of Pisot type. Central sets, first introduced by Furstenberg
using notions from topological dynamics, constitute a special class of subsets
of $\nats$ possessing strong combinatorial properties: Each central set
contains arbitrarily long arithmetic progressions, and solutions to all
partition regular systems of homogeneous linear equations. We give an
equivalent reformulation of the strong coincidence condition in terms of
central sets and minimal idempotent ultrafilters in the Stone-\v{C}ech
compactification $\beta \nats .$ This provides a new arithmetical approach to
an outstanding conjecture in tiling theory, the Pisot substitution conjecture.
The results in this paper rely on interactions between different areas of
mathematics, some of which had not previously been directly linked: They
include the general theory of combinatorics on words, abstract numeration
systems, tilings, topological dynamics and the algebraic/topological properties
of Stone-\v{C}ech compactification of $\nats.$


title:
Efficient DFT+U calculations of ballistic electron transport:
  Application to Au monatomic chains with a CO impurity

abstract:
  An efficient method for computing the Landauer-Buettiker conductance of an
open quantum system within DFT+U is presented. The Hubbard potential is
included in electronic structure and transport calculations as a simple
renormalization of the non-local pseudopotential coefficients by restricting
the integration for the on-site occupations within the cutoff spheres of the
pseudopotential. We apply the methodology to the case of an Au monatomic chain
in presence of a CO molecule adsorbed on it. We show that the Hubbard U
correction removes the spurious magnetization in the pristine Au chain at the
equilibrium spacing, as well as the unphysical contribution of d electrons to
the conductance, resulting in a single (spin-degenerate) transmission channel
and a more realistic conductance of 1 G_0 . We find that the conductance
reduction due to CO adsorption is much larger for the atop site than for the
bridge site, so that the general picture of electron transport in stretched Au
chains given by the local density approximation remains valid at the
equilibrium Au-Au spacing within DFT+U.


title:
Renormalized entropy for one dimensional discrete maps: periodic and
  quasi-periodic route to chaos and their robustness

abstract:
  We apply renormalized entropy as a complexity measure to the logistic and
sine-circle maps. In the case of logistic map, renormalized entropy decreases
(increases) until the accumulation point (after the accumulation point up to
the most chaotic state) as a sign of increasing (decreasing) degree of order in
all the investigated periodic windows, namely, period-2, 3, and 5, thereby
proving the robustness of this complexity measure. This observed change in the
renormalized entropy is adequate, since the bifurcations are exhibited before
the accumulation point, after which the band-merging, in opposition to the
bifurcations, is exhibited. In addition to the precise detection of the
accumulation points in all these windows, it is shown that the renormalized
entropy can detect the self-similar windows in the chaotic regime by exhibiting
abrupt changes in its values. Regarding the sine-circle map, we observe that
the renormalized entropy detects also the quasi-periodic regimes by showing
oscillatory behavior particularly in these regimes. Moreover, the oscillatory
regime of the renormalized entropy corresponds to a larger interval of the
nonlinearity parameter of the sine-circle map as the value of the frequency
ratio parameter reaches the critical value, at which the winding ratio attains
the golden mean.


title: Soliton dynamics in the multiphoton plasma regime

abstract:
  Solitary waves have consistently captured the imagination of scientists,
ranging from fundamental breakthroughs in spectroscopy and metrology enabled by
supercontinuum light, to gap solitons for dispersionless slow-light, and
discrete spatial solitons in lattices, amongst others. Recent progress in
strong-field atomic physics include impressive demonstrations of attosecond
pulses and high-harmonic generation via photoionization of free-electrons in
gases at extreme intensities of 1014 Wcm2. Here we report the first
phase-resolved observations of femtosecond optical solitons in a semiconductor
microchip, with multiphoton ionization at picojoule energies and 1010 Wcm2
intensities. The dramatic nonlinearity leads to picojoule observations of
free-electron-induced blue-shift at 1016 cm3 carrier densities and self-chirped
femtosecond soliton acceleration. Furthermore, we evidence the time-gated
dynamics of soliton splitting on-chip, and the suppression of soliton
recurrence due to fast free-electron dynamics. These observations in the highly
dispersive slow-light media reveal a rich set of physics governing
ultralow-power nonlinear photon-plasma dynamics.


title:
Nuclear asymmetry energy and isovector stiffness within the effective
  surface approximation

abstract:
  The isoscalar and isovector particle densities and the surface tension
coefficients at the average binding energy are used to derive analytical
expressions of the neutron skin thickness and the isovector stiffness of sharp
edged proton-neutron asymmetric nuclei. For most Skyrme forces these quantities
are significantly larger than the well known ones. Using the analytical
isovector surface energy constants in the framework of the hydrodynamical and
the Fermi-liquid droplet models the mean energies and the sum rules of the
isovector giant dipole resonances are in fair agreement with the experimental
data.


title:
Overview of large N QCD with chemical potential at weak and strong
  coupling

abstract:
  In this note we summarize the results from a longer article on obtaining the
QCD phase diagram as a function of the temperature and chemical potential at
large Nc and large Nf in the weak and the strong coupling limits. The weak
coupling phase diagram is obtained from the Polyakov line order parameter, and
the quark number, calculated using 1-loop perturbation theory for QCD
formulated on S^1 x S^3. The strong coupling phase diagram is obtained from the
same observables calculated at leading order in the lattice strong coupling and
hopping parameter expansions. We show that the matrix models in these two
limits agree at temperatures and chemical potentials which are not too high,
such that observables in the strongly-coupled theory can be obtained from the
observables in the weakly-coupled theory, and vice versa, using a simple
transformation of variables.


title: AGN jet physics and apparent opening angles

abstract:
  We present a new method to measure Gamma*theta_j in flux-limited samples of
active galactic nuclei (AGN) jets, where Gamma is the bulk Lorentz factor and
theta_j is the jet's half-opening angle. The Gamma*theta_j parameter is
physically important for models of jet launching, and also determines the
effectiveness of jet instabilities and magnetic reconnection. We measure
Gamma*theta_j by analyzing the observed distribution of apparent opening angles
in very long baseline interferometry (VLBI) flux-limited samples of jets, given
some prior knowledge of the active galactic nuclei (AGN) radio luminosity
function. We then apply this method to the MOJAVE flux-limited sample of radio
loud objects and find Gamma*theta_j = 0.1 +- 0.03, which implies that AGN jets
are subject to a variety of physical processes that require causal connection.


title:
Towards a complete understanding of pseudogap and pairing mechanisms in
  high-temperature superconducting cuprates

abstract:
  Unveiling the nature of the pseudogap and its relation to both
superconductivity and antiferromagnetic Mott insulators, the pairing mechanism,
and a non-Fermi liquid phase is a key issue for understanding high temperature
superconductivity in cuprates. A number of experimental results gathered
especially in recently years have revealed an unexpected inhomogeneous nature
of cuprates at the nanoscale, indicating the fundamental inapplicability of the
conventional theories based on homogeneous systems. Here we show a microscopic
model of pseudogap and pairing mechanisms on the basis of the consideration of
the spin state around a bound hole in a CuO2 plane and the resulting magnetic
orders, leading eventually to the spin-Peierls distortion responsible for the
Cooper pair formation. The present model fits and accounts for the accumulated
experimental findings reported previously for cuprates, including stripe-like
electronic order, breaking of the rotational symmetry, and the so-called 1/8
anomaly. We believe that the present model can help to develop a complete
theoretical framework applicable to a large family of high-temperature
superconductors, including ferropnictides and ferrochalcogenides.


title:
The new technique for the determination of the stellar initial mass
  function of unresolved stellar populations

abstract:
  We present the new technique for the determination of the low-mass slope of
the stellar mass function from the pixel-space fitting of integrated light
spectra. This technique is the extension of the NBursts full spectral fitting
technique. It can be used to constrain the stellar initial mass function (IMF)
of compact stellar systems having high relaxation timescales (Hubble time or
more). We used Monte-Carlo simulations with mock spectra to test the technique
and conclude that: (1) age, metallicity, and IMF can be very precisely
determined in the first "unrestricted" variant of the code for high
signal-to-noise datasets (S/N=100, R=7000 give the uncertainty of alpha of
about 0.1); (2) adding the M/L information significantly improves the precision
and reduces the degeneracies, however systematic errors in M/L will translate
into offsets in the IMF slope.


title:
Asymptotic symmetries at null infinity and local conformal properties of
  spin coefficients

abstract:
  We show that the symmetry algebra of asymptotically flat four dimensional
spacetimes at null infinity in the sense of Newman and Unti is isomorphic to
the direct sum of the abelian algebra of infinitesimal conformal rescalings
with bms4. We then work out the local conformal properties of the relevant
Newman-Penrose coefficients, as well as the surface charges and their algebra.


title:
Measurement of the top-antitop production cross section in the tau+jets
  channel in pp collisions at sqrt(s) = 7 TeV

abstract:
  The top-quark pair production cross section in 7 TeV center-of-mass energy
proton-proton collisions is measured using data collected by the CMS detector
at the LHC. The measurement uses events with one jet identified as a
hadronically decaying tau lepton and at least four additional energetic jets,
at least one of which is identified as coming from a b quark. The analyzed data
sample corresponds to an integrated luminosity of 3.9 inverse femtobarns
recorded by a dedicated multijet plus hadronically decaying tau trigger. A
neural network has been developed to separate the top-quark pairs from the
W+jets and multijet backgrounds. The measured value of sigma(ttbar) = 152 +/-
12 (stat.) +/- 32 (syst.) +/- 3 (lum.) pb is consistent with the standard model
predictions.


title:
Growth of dust grains in a low-metallicity gas and its effect on the
  cloud fragmentation

abstract:
  In a low-metallicity gas, rapid cooling by dust thermal emission is
considered to induce cloud fragmentation and play a vital role in the formation
of low-mass stars (<~ 1 M_sun) in metal-poor environments. We investigate how
the growth of dust grains through accretion of heavy elements in the gas phase
onto grain surfaces alters the thermal evolution and fragmentation properties
of a collapsing gas cloud. We calculate directly grain growth and dust emission
cooling in a self-consistent manner. We show that MgSiO3 grains grow
sufficiently at gas densities nH = 10^{10}, 10^{12}, and 10^{14} /cc for
metallicities Z = 10^{-4}, 10^{-5}, and 10^{-6} Zsun, respectively, where the
cooling of the collapsing gas cloud is enhanced. The condition for efficient
dust cooling is insensitive to the initial condensation factor of pre-existing
grains within the realistic range of 0.001--0.1, but sensitive to metallicity.
The critical metallicity is Zcrit ~ 10^{-5.5} Zsun for the initial grain radius
r_{MgSiO3,0} <~ 0.01 um and Zcrit ~ 10^{-4.5} Zsun for r_{MgSiO3,0} >~ 0.1 um.
The formation of a recently discovered low-mass star with extremely low
metallicity (<= 4.5x10^{-5} Zsun) could have been triggered by grain growth.


title: Exploring the spectroscopic properties of relic radiogalaxies

abstract:
  From an optical spectroscopic survey of 3CR radiogalaxies (RGs) with z<0.3,
we discovered three objects characterized by an extremely low level of gas
excitation and a large deficit of line emission with respect to RGs of similar
radio luminosity. We interpreted these objects as relic active galactic nuclei
(AGN), i.e., sources observed after a large drop in their nuclear activity. We
here present new spectroscopic observations for these three galaxies and for a
group of "candidate" relics. None of the candidates can be convincingly
confirmed. From the new data for the three relics, we estimate the density of
the line-emitting gas. This enables us to explore the temporal evolution of the
line ratios after the AGN "death". The characteristic timescale is the
light-crossing time of the emission line region, a few thousand years, too
short to correspond to a substantial population of relic RGs. Additional
mechanisms of gas ionization, such as "relic shocks" from their past high power
phase or stellar sources, should also be considered to account for the
spectroscopic properties of the relic RGs. Relic RGs appear to be a mixed bag
of sources in different phases of evolution, including AGN recently (~10,000
years ago) quenched, galaxies that have been inactive for at least one million
years, and objects caught during the transition from a powerful RG to a low
power FRI source.


title:
Generalized Householder Transformations for the Complex Symmetric
  Eigenvalue Problem

abstract:
  We present an intuitive and scalable algorithm for the diagonalization of
complex symmetric matrices, which arise from the projection of
pseudo--Hermitian and complex scaled Hamiltonians onto a suitable basis set of
"trial" states. The algorithm diagonalizes complex and symmetric
(non--Hermitian) matrices and is easily implemented in modern computer
languages. It is based on generalized Householder transformations and relies on
iterative similarity transformations T -> T' = Q^T T Q, where Q is a complex
and orthogonal, but not unitary, matrix, i.e, Q^T equals Q^(-1) but Q^+ is
different from Q^(-1). We present numerical reference data to support the
scalability of the algorithm. We construct the generalized Householder
transformations from the notion that the conserved scalar product of
eigenstates Psi_n and Psi_m of a pseudo-Hermitian quantum mechanical
Hamiltonian can be reformulated in terms of the generalized indefinite inner
product [integral of the product Psi_n(x,t) Psi_m(x,t) over dx], where the
integrand is locally defined, and complex conjugation is avoided. A few example
calculations are described which illustrate the physical origin of the ideas
used in the construction of the algorithm.

categories: quant-ph math-ph math.MP physics.atom-ph


title: Controlled formation and reflection of a bright solitary matter-wave

abstract:
  Solitons are non-dispersive wave solutions that arise in a diverse range of
nonlinear systems, stablised by a focussing or defocussing nonlinearity. First
observed in shallow water, solitons have subsequently been studied in many
other fields including nonlinear optics, biophysics, astrophysics, plasma and
particle physics. They are characterised by well localised wavepackets that
maintain their initial shape and amplitude for all time, even following
collisions with other solitons. Here we report the controlled formation of
bright solitary matter-waves, the 3D analog to solitons, from Bose-Einstein
condensates of 85Rb and observe their propagation in an optical waveguide.
These results pave the way for new experimental studies of bright solitary
matterwave dynamics to elucidate the wealth of existing theoretical work and to
explore an array of potential applications including novel interferometric
devices, the study of short-range atom-surface potentials and the realisation
of Schrodingercat states.


title: Eigenvalues of the Adin-Roichman Matrices

abstract:
  We find the spectrum of the Walsh-Hadamard type matrices defined by R.Adin
and Y.Roichman in their recent work on character formulas and descent sets for
the symmetric group.


title:
Above-threshold ionization with highly-charged ions in super-strong
  laser fields: I. Coulomb-corrected strong field approximation

abstract:
  Aiming at the investigation of above-threshold ionization in super-strong
laser fields with highly charged ions, we develop a Coulomb-corrected strong
field approximation (SFA). The influence of the Coulomb potential of the atomic
core on the ionized electron dynamics in the continuum is taken into account
via the eikonal approximation, treating the Coulomb potential perturbatively in
the phase of the quasi-classical wave function of the continuum electron. In
this paper the formalism of the Coulomb-corrected SFA for the nonrelativistic
regime is discussed employing velocity and length gauge. Direct ionization of a
hydrogen-like system in a strong linearly polarized laser field is considered.
The relation of the results in the different gauges to the
Perelomov-Popov-Terent'ev imaginary-time method is discussed.


title:
Effect of Energy Loss On Azimuthal Correlation of charm and correlated
  charm decay in collision of lead nuclei at sqrt{s} = 2.76 A TeV

abstract:
  We present the effect of energy loss of charm/anti-charm produced in a
relativistic heavy ion collision as they traverse the resulting quark gluon
plasma on the azimuthal correlation of c\bar{c} and D\bar{D} pairs and their
correlated decay into leptons. We employ an empirical model of energy loss by
charm quark energy loss and find that the consequences are easily discernible
as different cuts on their momenta are applied. We also notice a modest
increase in the invariant mass spectrum of dileptons from correlated decay as
mentioned above due to energy loss.


title: Non-unital non-Markovianity of quantum dynamics

abstract:
  We show that Breuer-Laine-Piilo (BLP) non-Markovianity cannot capture the
dynamical information in the non-unital aspect of the quantum dynamics.
Moreover, we provide a measure on the effect of the non-unitality of quantum
processes on the infinitesimal non-divisibility. This measure can be used as a
supplement to BLP non-Markovianity for non-unital quantum processes. A measure
on the degree of the non-unital behavior of quantum processes is also given in
this paper.


title:
Above-threshold ionization with highly-charged ions in super-strong
  laser fields: II. Relativistic Coulomb-corrected strong field approximation

abstract:
  We develop a relativistic Coulomb-corrected strong field approximation (SFA)
for the investigation of spin effects at above-threshold ionization in
relativistically strong laser fields with highly charged hydrogen-like ions.
The Coulomb-corrected SFA is based on the relativistic eikonal-Volkov wave
function describing the ionized electron laser-driven continuum dynamics
disturbed by the Coulomb field of the ionic core. The SFA in different
partitions of the total Hamiltonian is considered. The formalism is applied for
direct ionization of a hydrogen-like system in a strong linearly polarized
laser field. The differential and total ionization rates are calculated
analytically. The relativistic analogue of the Perelomov-Popov-Terent'ev
ionization rate is retrieved within the SFA technique. The physical relevance
of the SFA in different partitions is discussed.


title:
High Capacity Indoor & Hotspot Wireless System in Shared Spectrum - A
  Techno-Economic Analysis

abstract:
  Predictions for wireless and mobile Internet access suggest exponential
traffic increase particularly in inbuilding environments. Non-traditional
actors such as facility owners have a growing interest in deploying and
operating their own indoor networks to fulfill the capacity demand. Such local
operators will need spectrum sharing with neighboring networks because they are
not likely to have their own dedicated spectrum. Management of inter-network
interference then becomes a key issue for high capacity provision. Tight
operator-wise cooperation provides superior performance, but at the expense of
high infrastructure cost and business-related barriers. Limited coordination on
the other hand causes harmful interference between operators which in turn will
require even denser networks. In this paper, we propose a techno-economic
analysis framework for investigating and comparing the strategies of the indoor
operators. We refine a traditional network cost model by introducing new
inter-operator cost factors. Then, we present a numerical example to
demonstrate how the proposed framework can help us comparing different operator
strategies. Finally, we suggest areas for future research.


title:
Interplay of classical and quantal features within the coherent state
  model

abstract:
  The classical and quantal features of a quadrupole coherent state and its
projections over angular momentum and boson number are quantitatively analyzed
in terms of the departure of the Heisenberg uncertainty relations from the
classical limit. This study is performed alternatively for two choices of the
pairs of conjugate coordinates. The role of deformation as mediator of
classical and quantal behaviors is also commented. Although restoring the
rotational and gauge symmetries makes the quantal features manifest dominantly
for small deformation, these are blurred by increasing the deformation which
pushes the system toward a classical limit.


title: Three-dimensional ghost imaging ladar

abstract:
  Compared with two-dimensional imaging, three-dimensional imaging is much more
advantageous to catch the characteristic information of the target for remote
sensing. We report a range-resolving ghost imaging ladar system together with
the experimental demonstration of three-dimensional remote sensing with a large
field of view. The experiments show that, by measuring the correlation function
of intensity fluctuations between two light fields, a three-dimensional map at
about 1.0 km range with 25 cm resolution in lateral direction and 60 cm
resolution in axial direction has been achieved by time-resolved measurements
of the reflection signals.


title: On generalized 3-manifolds which are not homologically locally connected

abstract:
  We show that the classical example $X$ of a 3-dimensional generalized
manifold constructed by van Kampen is another example of not homologically
locally connected (i.e. not HLC) space. This space $X$ is not locally
homeomorphic to any of the compact metrizable 3-dimensional manifolds
constructed in our earlier paper which are not HLC spaces either.


title:
Minimum vertex cover problems on random hypergraphs: replica symmetric
  solution and a leaf removal algorithm

abstract:
  We study minimum vertex cover problems on random \alpha-uniform hypergraphs
using two different approaches, a replica method in statistical mechanics of
random systems and a leaf removal algorithm. It is found that there exists a
phase transition at the critical average degree e/(\alpha-1). Below the
critical degree, a replica symmetric ansatz in the statistical-mechanical
method holdsand the algorithm estimates a solution of the problem which
coincide with that by the replica method. In contrast, above the critical
degree, the replica symmetric solution becomes unstable and these methods fail
to estimate the exact solution.These results strongly suggest a close relation
between the replica symmetry and the performance of approximation algorithm.


title: Balls minimize trace constants in BV

abstract:
  Balls are shown to have the smallest optimal constant, among all admissible
Euclidean domains, in Poincar\'e type boundary trace inequalities for functions
of bounded variation with vanishing median or mean value.


title:
DNS of horizontal open channel flow with finite-size, heavy particles at
  low solid volume fraction

abstract:
  We have performed direct numerical simulation of turbulent open channel flow
over a smooth horizontal wall in the presence of finite-size, heavy particles.
The spherical particles have a diameter of approximately 7 wall units, a
density of 1.7 times the fluid density and a solid volume fraction of 0.0005.
The value of the Galileo number is set to 16.5, while the Shields parameter
measures approximately 0.2. Under these conditions, the particles are
predominantly located in the vicinity of the bottom wall, where they exhibit
strong preferential concentration which we quantify by means of Voronoi
analysis and by computing the particle-conditioned concentration field. As
observed in previous studies with similar parameter values, the mean streamwise
particle velocity is smaller than that of the fluid. We propose a new
definition of the fluid velocity "seen" by finite-size particles based on an
average over a spherical surface segment, from which we deduce in the present
case that the particles are instantaneously lagging the fluid only by a small
amount. The particle-conditioned fluid velocity field shows that the particles
preferentially reside in the low-speed streaks, leading to the observed
apparent lag. Finally, a vortex eduction study reveals that spanwise particle
motion is significantly correlated with the presence of vortices with the
corresponding sense of rotation which are located in the immediate vicinity of
the near-wall particles.


title: Lightlike surfaces with planar normal sections in Minkowski 3-space

abstract:
  In this paper we study lightlike surfaces of Minkowski 3- space such that
they have degenerate or non-degenerate planar normal sections. We first show
that every lightlike surface of Minkowski $3-$ space has degenerate planar
normal sections. Then we study lightlike surfaces with non-degenerate planar
normal sections and obtain a characterization for such lightlike surfaces.


title: The changing nebula around the hot R Coronae Borealis star DY Centauri

abstract:
  Among the distinguishing characteristics of the remarkable hot R Coronae
Borealis star DY Cen, which was recently found to be a spectroscopic binary, is
the presence of nebular forbidden lines in its optical spectrum. A compilation
of photometry from 1970 to the present suggests that the star has evolved to
higher effective temperatures. Comparison of spectra from 2010 with earlier
spectra show that between 2003 and 2010, the 6717 and 6730 A emission lines of
[S II] underwent a dramatic change in their fluxes suggesting an increase in
the nebula's electron density of 290 cm-3 to 3140 cm-3 from 1989 to 2010 while
the stellar temperature increased from 19500 K to 25000 K. The nebular radius
is about 0.02 pc, 60000 times bigger than the semimajor axis of DY Cen binary
system. Rapid changes of stellar temperature and its response by the nebula
demonstrate stellar evolution in action.


title: Half-lightlike submanifolds with planar normal section in $R_{2}^{4}$

abstract:
  We investigate half-lightlike submanifolds with planar normal sections of
four dimensional pseudo Euclidean space. We obtain necessary and sufficient
conditions for a half-lightlike submanifold of $R_{2}^{4}$ such that it has
degenerate or non-degenerate planar normal sections.


title:
Comment on star-star relations in statistical mechanics and elliptic
  gamma-function identities

abstract:
  We prove a recently conjectured star-star relation, which plays the role of
an integrability condition for a class of 2D Ising-type models with
multicomponent continuous spin variables. Namely, we reduce this relation to an
identity for elliptic gamma functions, previously obtained by Rains.

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


title: Bound states in the continuum driven by AC fields

abstract:
  We report the formation of bound states in the continuum driven by AC fields.
This system consists of a quantum ring connected to two leads. An AC side-gate
voltage controls the interference pattern of the electrons passing through the
system. We model the system by two sites in parallel connected to two
semi-infinite lattices. The energy of these sites change harmonically with
time. We obtain the transmission probability and the local density of states at
the ring sites as a function of the parameters that define the system. The
transmission probability displays a Fano profile when the energy of the
incoming electron matches the driving frequency. Correspondingly, the local
density of states presents a narrow peak that approaches a Dirac delta function
in the weak coupling limit. We attribute these features to the presence of
bound states in the continuum.