title: Noncritical holomorphic functions on Stein spaces

abstract:
  We prove that every reduced Stein space admits a holomorphic function without
critical points. Furthermore, any closed discrete subset of such a space is the
critical locus of a holomorphic function. We also show that for every complex
analytic stratification with nonsingular strata on a reduced Stein space there
exists a holomorphic function whose restriction to every stratum is
noncritical. These result also provide some information on critical loci of
holomorphic functions on desingularizations of Stein spaces. In particular,
every 1-convex manifold admits a holomorphic function that is noncritical
outside the exceptional variety.


title:
LA-CTR: A Limited Attention Collaborative Topic Regression for Social
  Media

abstract:
  Probabilistic models can learn users' preferences from the history of their
item adoptions on a social media site, and in turn, recommend new items to
users based on learned preferences. However, current models ignore
psychological factors that play an important role in shaping online social
behavior. One such factor is attention, the mechanism that integrates
perceptual and cognitive features to select the items the user will consciously
process and may eventually adopt. Recent research has shown that people have
finite attention, which constrains their online interactions, and that they
divide their limited attention non-uniformly over other people. We propose a
collaborative topic regression model that incorporates limited, non-uniformly
divided attention. We show that the proposed model is able to learn more
accurate user preferences than state-of-art models, which do not take human
cognitive factors into account. Specifically we analyze voting on news items on
the social news aggregator and show that our model is better able to predict
held out votes than alternate models. Our study demonstrates that
psycho-socially motivated models are better able to describe and predict
observed behavior than models which only consider latent social structure and
content.


title:
Using Integral Dispersion Relations to Extend the LHC Reach for New
  Physics

abstract:
  Many models of electroweak symmetry breaking predict new particles with
masses at or just beyond LHC energies. Even if these particles are too massive
to be produced on-shell at the LHC, it may be possible to see evidence of their
existence through the use of integral dispersion relations (IDRs). Making use
of Cauchy's integral formula and the analyticity of the scattering amplitude,
IDRs are sensitive in principle to changes in the cross section at arbitrarily
large energies. We investigate some models of new physics. We find that a
sudden, order one increase in the cross section above new particle mass
thresholds can be inferred well below the threshold energy. On the other hand,
for two more physical models of particle production, we show that the reach in
energy and the signal strength of the IDR technique is greatly reduced. The
peak sensitivity for the IDR technique is shown to occur when the new particle
masses are near the machine energy, an energy where direct production of new
particles is kinematically disallowed, phase-space suppressed, or if
applicable, suppressed by the soft parton distribution functions. Thus, IDRs do
extend the reach of the LHC, but only to a window around $M_\chi\sim
\sqrt{s_{_{\rm LHC}}}$.


title: From Theory to Practice: Plug and Play with Succinct Data Structures

abstract:
  Engineering efficient implementations of compact and succinct structures is a
time-consuming and challenging task, since there is no standard library of
easy-to- use, highly optimized, and composable components. One consequence is
that measuring the practical impact of new theoretical proposals is a difficult
task, since older base- line implementations may not rely on the same basic
components, and reimplementing from scratch can be very time-consuming. In this
paper we present a framework for experimentation with succinct data structures,
providing a large set of configurable components, together with tests,
benchmarks, and tools to analyze resource requirements. We demonstrate the
functionality of the framework by recomposing succinct solutions for document
retrieval.


title:
Exact Canonically Conjugate Momenta to Quadrupole-Type Collective
  Coordinates and Derivation of Nuclear Quadrupole-Type Collective Hamiltonian

abstract:
  Exact canonically conjugate momenta Pi_{2mu} in quadrupole nuclear collective
motions are proposed. The basic idea lies in the introduction of a discrete
integral equation for the strict definition of canonically conjugate momenta to
collective variables phi_{2mu}. A part of our collective Hamiltonian, the
Pi_{2mu}-dependence of the kinetic part of the Hamiltonian, is given exactly.
Further, phi_{2mu}-dependence of the kinetic part of the Hamiltonian is also
given.


title: Painting Squares in $\Delta^2-1$ Shades

abstract:
  Cranston and Kim conjecture that if $G$ is a connected graph with maximum
degree $\Delta$ and $G$ is not a Moore Graph, then $\chi_l(G^2) \le
\Delta^2-1$; here $\chi_l$ is the list chromatic number. We prove their
conjecture; in fact, this upper bound holds even for online list chromatic
number.


title: Structural and Magnetic Properties of CoO-Pt core-shell nanoparticles

abstract:
  Using microemulsion methods, CoO-Pt core-shell nanoparticles (NPs), with
diameters of nominally 4 nm, were synthesized and characterized by
high-resolution transmission electron microscopy (HRTEM) and a suite of x-ray
spectroscopies, including diffraction (XRD), absorption (XAS), absorption
near-edge structure (XANES), and extended absorption fine structure (EXAFS),
which confirmed the existence of CoO cores and pure Pt surface layers. Using a
commercial magnetometer, the ac and dc magnetic properties were investigated
over a range of temperature (2 K $\leq$ T $\leq$ 300 K), magnetic field ($\leq$
50 kOe), and frequency ($\leq$ 1 kHz). The data indicate the presence of two
different magnetic regimes whose onsets are identified by two maxima in the
magnetic signals, with a narrow maximum centered at 6 K and a large one
centered at 37 K. The magnetic responses in these two regimes exhibit different
frequency dependences, where the maximum at high temperature follows a
Vogel-Fulcher law, indicating a superparamagnetic (SPM) blocking of interacting
nanoparticle moments and the maximum at low temperature possesses a power law
response characteristic of a collective freezing of the nanoparticle moments in
a superspin glass (SSG) state. This co-existence of blocking and freezing
behaviors is consistent with the nanoparticles possessing an
antiferromagnetically ordered core, with an uncompensated magnetic moment, and
a magnetically disordered interlayer between CoO core and Pt shell.


title:
Heavy quarkonium potential from Bethe-Salpeter wave function on the
  lattice

abstract:
  We propose a novel method for the determination of the interquark potential
together with quark "kinetic mass'' $m_Q$ from the equal-time $Q\bar{Q}$
Bethe-Salpeter (BS) amplitude in lattice QCD. Our approach allows us to
calculate spin-dependent $Q\bar{Q}$ potentials, e.g. the spin-spin potential,
as well. In order to investigate several systematic uncertainties on such
$Q\bar{Q}$ potentials, we carry out lattice QCD simulations using quenched
gauge configurations generated with the single plaquette gauge action with
three different lattice spacings, $a \approx$ 0.093, 0.068 and 0.047 fm, and
two different physical volumes, $L \approx$ 2.2 and 3.0 fm. For heavy quarks,
we employ the relativistic heavy quark (RHQ) action which can control large
discretization errors introduced by large quark mass $m_Q$. The
spin-independent central $Q\bar{Q}$ potential for the charmonium system yields
the "Coulomb plus linear'' behavior with good scaling and small volume
dependence. We explore the quark mass dependence over the wide mass range from
the charm to beyond the bottom region, and then demonstrate that the
spin-independent central $Q\bar{Q}$ potential in the $m_Q \to \infty$ limit is
fairly consistent with the static $Q\bar{Q}$ potential obtained from Wilson
loops. The spin-spin potential at finite quark mass provides a repulsive
interaction with a finite range, which becomes narrower as the quark mass
increases. We also discuss the applicability of the $1/m_Q$ expansion approach
for the spin-spin potential.


title:
The Contribution of z<6 Sources to the Spatial Coherence in the
  Unresolved Cosmic near-Infrared and X-ray Backgrounds

abstract:
  A spatial clustering signal has been established in Spitzer/IRAC measurements
of the unresolved Cosmic near-Infrared Background (CIB) out to large angular
scales, ~1 deg. This CIB signal, while significantly exceeding the contribution
from the remaining known galaxies, was further found to be coherent at a highly
statistically significant level with the unresolved soft Cosmic X-ray
Background (CXB). This measurement probes the unresolved CXB to very faint
source levels using deep near-IR source subtraction. We study contributions
from extragalactic populations at low to intermediate redshifts to the measured
positive cross-power signal of the CIB fluctuations with the CXB. We model the
X-ray emission from AGN, normal galaxies and hot gas residing in virialized
structures, calculating their CXB contribution including their spatial
coherence with all infrared emitting counterparts. We use a halo model
framework to calculate the auto and cross-power spectra of the unresolved
fluctuations based on the latest constraints of the halo occupation
distribution and the biasing of AGN, galaxies and diffuse emission. At small
angular scales (<1'), the 4.5mic vs 0.5-2 keV coherence can be explained by
shot noise from galaxies and AGN. However, at large angular scales (~10 arcmin)
we find that the net contribution from the modeled populations is only able to
account for ~3% of the measured CIBxCXB cross-power. The discrepancy suggests
that the CIBxCXB signal originates from the same unknown source population
producing the CIB clustering signal out to ~1 deg.


title: Separable-stable representations of a compression body

abstract:
  Let M be a hyperbolizable, nontrivial compression body without toroidal
boundary components. In this paper, we characterize which discrete and faithful
representations of the fundamental group of M into PSL(2,C) are
separable-stable. The set of separable-stable representations forms a domain of
discontinuity for the action of the outer automorphism group of the fundamental
group of M on the PSL(2,C)-character variety of M.


title: Scalar $\phi^4$ field theory for active-particle phase separation

abstract:
  Recent theories predict phase separation among orientationally disordered
active particles whose propulsion speed decreases rapidly enough with density.
Coarse-grained models of this process show time-reversal symmetry (detailed
balance) to be restored for uniform states, but broken by gradient terms; hence
detailed-balance violation is strongly coupled to interfacial phenomena. To
explore the subtle generic physics resulting from such coupling we here
introduce `Active Model B'. This is a scalar $\phi^4$ field theory (or
phase-field model) that minimally violates detailed balance via a leading-order
square-gradient term. We find that this additional term has modest effects on
coarsening dynamics, but alters the static phase diagram by creating a jump in
(thermodynamic) pressure across flat interfaces. Both results are surprising,
since interfacial phenomena are always strongly implicated in coarsening
dynamics but are, in detailed-balance systems, irrelevant for phase equilibria.


title: Mass Renormalization in String Theory: Special States

abstract:
  String theory gives a well defined procedure for computing the S-matrix of
BPS or a class of massless states, but similar calculation for general massive
states is plagued with difficulties due to mass renormalization effect. In this
paper we describe a procedure for computing the renormalized masses and
S-matrix elements in bosonic string theory for a special class of massive
states which do not mix with unphysical states under renormalization. Even
though this requires working with off-shell amplitudes which are ambiguous, we
show that the renormalized masses and S-matrix elements are free from these
ambiguities. We also argue that the masses and S-matrix elements for general
external states can be found by examining the locations of the poles and the
residues of the S-matrix of special states. Finally we discuss generalizations
to heterotic and superstring theories.


title: Derived equivalences between triangular matrix algebras

abstract:
  In this paper we study derived equivalences between triangular matrix
algebras using certain classical recollements. We show that special properties
of these recollements actually characterize triangular matrix algebras, and
describe methods to construct tilting modules and tilting complexes inducing
derived equivalences between them.


title: Multi-target Radar Detection within a Sparsity Framework

abstract:
  Traditional radar detection schemes are typically studied for single target
scenarios and they can be non-optimal when there are multiple targets in the
scene. In this paper, we develop a framework to discuss multi-target detection
schemes with sparse reconstruction techniques that is based on the
Neyman-Pearson criterion. We will describe an initial result in this framework
concerning false alarm probability with LASSO as the sparse reconstruction
technique. Then, several simulations validating this result will be discussed.
Finally, we describe several research avenues to further pursue this framework.


title: On the Sodium versus Iron Correlation in Late B-Type Stars

abstract:
  With an aim to study whether the close correlation between [Na/H] and [Fe/H]
recently found in A-type stars further persists in the regime of B-type stars,
the abundances of Na were determined for 30 selected sharp-lined late B-type
stars (10000K < T_eff < 14000K) from the Na I 5890/5896 doublet. These Na
abundances were then compared with the O and Fe abundances (derived from the O
I 6156-8 and Fe II 6147/6149 lines) showing anti-correlated peculiarities. It
turned out that, unlike the case of A-type stars, [Na/H] is roughly constant at
a slightly subsolar level ([Na/H] ~ -0.2 (+/-0.2)) without any significant
correlation with [Fe/H] which shows considerable dispersion ranging from ~ -0.6
to ~ +1.0. This may serve as an important observational constraint for
understanding the abundance peculiarities along with the physical mechanism of
atomic diffusion in upper main-sequence stars of late A through late B-type
including Am and HgMn stars.


title: Hopf algebraic techniques applied to super algebraic groups

abstract:
  Reproducing my talk at Algebra Symposium held at Hiroshima University, August
26--29, 2013, I review recent results on super algebraic groups, emphasizing
results obtained by myself and my coauthors using Hopf algebraic techniques.
The results are all basic, and I intend to make this report into a somewhat
informal introduction to the subject.


title:
Investigation of Magnetic Proximity Effect inTa/YIG Bilayer Hall Bar
  Structure

abstract:
  In this work, the investigation of magnetic proximity effect was extended to
Ta which has been reported to have a negative spin Hall angle.
Magnetoresistance and Hall measurements for in-plane and out-of-plane applied
magnetic field sweeps were carried out at room temperature. The size of the MR
ratio observed (~10-5) and its magnetization direction dependence are similar
to that reported in Pt/YIG, both of which can be explained by the spin Hall
magnetoresistance theory. Additionally, a flip of magnetoresistance polarity is
observed at 4 K in the temperature dependent measurements, which can be
explained by the magnetic proximity effect induced anisotropic
magnetoresistance at low temperature. Our findings suggest that both magnetic
proximity effect and spin Hall magnetoresistance have contribution to the
recently observed unconventional magnetoresistance effect.


title:
High flux symmetry of the Spherical Hohlraum with Octahedral 6LEHs at a
  Golden Hohlraum-to-capsule Radius ratio

abstract:
  In the present Letter, we investigate a spherical hohlraums with octahedral
six laser entrance holes (LEHs) for inertial fusion, which has advantages over
the conventional hohlraums of cylindrical geometry since it contains only one
cone at each LEH and the problems caused by the beam overlap and crossed-beam
energy transfer can be eliminated and the backscattering can be reduced. In
particular, our study indicates that at a specific hohlraum-to-capsule radius
ratio, i.e., the golden ratio, the flux asymmetry on capsule can be
significantly reduced. From our study, this golden octahedral hohlraum has
robust high symmetry, low plasma filling and low backscattering. Though the
golden octahedral hohlraum needs $30\%$ more laser energy than traditional
cylinder for producing the ignition radiation pulse of 300 eV, it is worth for
a robust high symmetry and low backscattering. The proposed octahedral hohlraum
is also flexible and can be applicable to diverse inertial fusion drive
approaches. As an application, we design an ignition octahedral hohlraum for
the hybrid drive.


title: Dynamic Network Formation with Incomplete Information

abstract:
  How do networks form and what is their ultimate topology? Most of the
literature that addresses these questions assumes complete information: agents
know in advance the value of linking to other agents, even with agents they
have never met and with whom they have had no previous interaction (direct or
indirect). This paper addresses the same questions under what seems to us to be
the much more natural assumption of incomplete information: agents do not know
in advance -- but must learn -- the value of linking to agents they have never
met. We show that the assumption of incomplete information has profound
implications for the process of network formation and the topology of networks
that ultimately form. Under complete information, the networks that form and
are stable typically have a star, wheel or core-periphery form, with high-value
agents in the core. Under incomplete information, the presence of positive
externalities (the value of indirect links) implies that a much wider
collection of network topologies can emerge and be stable. Moreover, even when
the topologies that emerge are the same, the locations of agents can be very
different. For instance, when information is incomplete, it is possible for a
hub-and-spokes network with a low-value agent in the center to form and endure
permanently: an agent can achieve a central position purely as the result of
chance rather than as the result of merit. Perhaps even more strikingly: when
information is incomplete, a connected network could form and persist even if,
when information were complete, no links would ever form, so that the final
form would be a totally disconnected network. All of this can occur even in
settings where agents eventually learn everything so that information, although
initially incomplete, eventually becomes complete.


title: Hodge Diamonds and Adjoint Orbits

abstract:
  We present a Macaulay2 package that produces compactifications of adjoint
orbits and of the fibres of symplectic Lefschetz fibrations on them. We use
Macaulay2 functions to calculate the corresponding Hodge diamonds, which then
reveal topological information about the Lefschetz fibrations.


title:
Topological-collaborative approach for disambiguating authors' names in
  collaborative networks

abstract:
  Concepts and methods of complex networks have been employed to uncover
patterns in a myriad of complex systems. Unfortunately, the relevance and
significance of these patterns strongly depends on the reliability of the data
sets. In the study of collaboration networks, for instance, unavoidable noise
pervading author's collaboration datasets arises when authors share the same
name. To address this problem, we derive a hybrid approach based on authors'
collaboration patterns and on topological features of collaborative networks.
Our results show that the combination of strategies, in most cases, performs
better than the traditional approach which disregards topological features. We
also show that the main factor for improving the discriminability of homonymous
authors is the average distance between authors. Finally, we show that it is
possible to predict the weighting associated to each strategy compounding the
hybrid system by examining the discrimination obtained from the traditional
analysis of collaboration patterns. Once the methodology devised here is
generic, our approach is potentially useful to classify many other networked
systems governed by complex interactions.


title: Analytical estimation of ATF beam halo distribution

abstract:
  In order to study the background status in the ATF2 beam line and the
interaction point (IP), this paper developed an analytical method to give the
estimation of ATF beam halo distribution based on K. Hirata and K. Yokoya's
theory. The equilibrium particle distribution of beam tail in ATF damping ring,
when each electron is being affected by, in addition to the synchrotron
radiation damping effects, several stochastic processes, such as beam-gas
scattring, beam-gas bremsstrahlung and intra-beam scattering, was presented.
This method is common and can be applied on other electron rings.


title:
Empirical Investigation on the Impact of Hydrogen Collisions for the
  Formation of CI 1.07 mu~m Lines Based on the Solar Center-to-Limb Variation

abstract:
  With an aim of examining the validity of non-LTE line-formation calculations
for the strong C I lines of multiplet 1 at 1.068-1.069 mu~m, especially in
terms of the treatment of collisions with neutral hydrogen (H I) atoms, we
computed theoretical equivalent widths (W_lambda) of these lines corresponding
to specific intensities of different angles (mu = cos(theta)) on the solar disk
under various conditions, which were then compared with the empirical W_lambda
vs. mu relations obtained from our spectroscopic observations using the
Domeless Solar Telescope at Hida Observatory. It turned out that our
observational data are almost consistent with the theoretical simulations done
with the H I collision rates computed with the classical formula, which
suggests that the necessity of its significant revision (e.g., considerable
reduction) is unlikely.


title: Enhanced Superconductivity up to 43 K by P/Sb Doping of Ca1-xLaxFeAs2

abstract:
  The effects of isovalent doping on the superconducting transition temperature
Tc in novel 112-type iron arsenide Ca1-xLaxFeAs2 were studied by conducting
measurements of electrical resistivity rho and magnetization M. P or Sb doping
strongly enhances Tc: P-doped Ca0.84La0.16FeAs2 and Sb-doped Ca0.85La0.15FeAs2
exhibited Tc of 41 and 43 K, respectively, while Ca0.85La0.15FeAs2 without P/Sb
exhibited Tc = 35 K. These observations will give a hint for further enhancing
Tc of rare-earth doped Ca-Fe-As systems.


title: Distance to the SMC from eclipsing binaries

abstract:
  The preliminary distance to a long period eclipsing binary in the Small
Magellanic Cloud SMC108.1.14904 is presented. The binary system contains two
non-active G-type bright giants. The orbital period is 185 days and the orbit
is circular. Using surface brightness calibration we calculated distance
modulus to the system (m-M)= 19.02 +/- 0.04 (stat.) +/- 0.05 (syst.) mag, where
systematic error is dominated by uncertainty of surface brightness calibration.
This is a second eclipsing binary in the SMC analysed by our team.


title: Spin Orbit Interaction and Isotropic Electronic Transport in Graphene

abstract:
  Broken symmetries in graphene affect the massless nature of its charge
carriers. We present an analysis of scattering by defects in graphene in the
presence of spin-orbit interactions (SOIs). A characteristic constant ratio
($\simeq 2$) of the transport to elastic times for massless electrons signals
the anisotropy of the scattering. We show that SOIs lead to a drastic decrease
of this ratio, especially at low carrier concentrations, while the scattering
becomes increasingly isotropic. As the strength of the SOI determines the
energy (carrier concentration) where this drop is more evident, this effect
could help evaluate these interactions through transport measurements.


title:
A stability condition for turbulence model: From EMMS model to
  EMMS-based turbulence model

abstract:
  The closure problem of turbulence is still a challenging issue in turbulence
modeling. In this work, a stability condition is used to close turbulence.
Specifically, we regard single-phase flow as a mixture of turbulent and
non-turbulent fluids, separating the structure of turbulence. Subsequently,
according to the picture of the turbulent eddy cascade, the energy contained in
turbulent flow is decomposed into different parts and then quantified. A
turbulence stability condition, similar to the principle of the
energy-minimization multi-scale (EMMS) model for gas-solid systems, is
formulated to close the dynamic constraint equations of turbulence, allowing
the heterogeneous structural parameters of turbulence to be optimized. We call
this model the `EMMS-based turbulence model', and use it to construct the
corresponding turbulent viscosity coefficient. To validate the EMMS-based
turbulence model, it is used to simulate two classical benchmark problems,
lid-driven cavity flow and turbulent flow with forced convection in an empty
room. The numerical results show that the EMMS-based turbulence model improves
the accuracy of turbulence modeling due to it considers the principle of
compromise in competition between viscosity and inertia.


title:
Long-range string orders and topological quantum phase transitions in
  the one-dimensional quantum compass model

abstract:
  In order to investigate the quantum phase transition in the one-dimensional
quantum compass model, we numerically calculate non-local string correlations,
entanglement entropy, and fidelity per lattice site by using the infinite
matrix product state representation with the infinite time evolving block
decimation method. In the whole range of the interaction parameters, we find
that the four distinct string orders characterize the four different Haldane
phases and the topological quantum phase transition occurs between the Haldane
phases. The critical exponents of the string order parameters {\beta}=1/8 and
the cental charges c=1/2 at the critical points show that the topological phase
transitions between the phases belong to an Ising type of universality classes.
In addition to the string order parameters, the singularities of the second
derivative of the ground state energies per site, the continuous and singular
behaviors of the von Neumann entropy, and the pinch points of the fidelity per
lattice site manifest that the phase transitions between the phases are of the
second-order, in contrast to the first-order transition suggested in pervious
studies.


title: Study of charmonium decays at BESIII

abstract:
  Based on the data samples collected at the energies of $J/\psi$,
$\psi(3686)$, $\psi(3770)$ and $\psi(4040)$ resonances with the BESIII detector
at the BEPCII storage ring, we present charmonium decays in two aspects. One is
the search for baryonic decays of $\psi(3770)$ and $\psi(4040)$, including
$\Lambda \bar\Lambda\pi^+\pi^-$, $\Lambda\bar\Lambda\pi^0$, $\Lambda
\bar\Lambda\eta$, $\Sigma^+ \bar\Sigma^-$, $\Sigma^0 \bar\Sigma^0$,
$\Xi^-\bar\Xi^+$ and $\Xi^0\bar\Xi^0$. None are observed, and upper limits are
set at the 90% confidence level. The other is the light hadron spectroscopy
from charmonium radiative decays, including the spin-parity analysis of the
$p\bar p$ mass-threshold enhancement in $J/\psi$ radiative decays and the
$\eta\eta$ system in $J/\psi\to\gamma\eta\eta$ radiative decays.


title:
A new optical field state as an output of diffusion channel when the
  input being number state

abstract:
  We theoretically propose a new optical field state which is named
Laguerre-polynomial-weighted chaotic field. We show that such state can be
implemented, i.e., when a number state enters into a diffusion channel, the
output state is just this kind of states. We solve the master equation
describing the diffusion process by using the summation method within ordered
product of operators and the entangled state representaion. The solution
manifestly shows how a pure state evolves into a mixed state. The physical
difference between the diffusion and the amplitude damping is pointed out.


title: Minimal Distances Between SCFTs

abstract:
  We study lower bounds on the minimal distance in theory space between
four-dimensional superconformal field theories (SCFTs) connected via broad
classes of renormalization group (RG) flows preserving various amounts of
supersymmetry (SUSY). For N=1 RG flows, the ultraviolet (UV) and infrared (IR)
endpoints of the flow can be parametrically close. On the other hand, for RG
flows emanating from a maximally supersymmetric SCFT, the distance to the IR
theory cannot be arbitrarily small regardless of the amount of (non-trivial)
SUSY preserved along the flow. The case of RG flows from N=2 UV SCFTs is more
subtle. We argue that for RG flows preserving the full N=2 SUSY, there are
various obstructions to finding examples with parametrically close UV and IR
endpoints. Under reasonable assumptions, these obstructions include: unitarity,
known bounds on the c central charge derived from associativity of the operator
product expansion, and the central charge bounds of Hofman and Maldacena. On
the other hand, for RG flows that break N=2 to N=1, it is possible to find IR
fixed points that are parametrically close to the UV ones. In this case, we
argue that if the UV SCFT possesses a single stress tensor, then such RG flows
excite of order all the degrees of freedom of the UV theory. Furthermore, if
the UV theory has some flavor symmetry, we argue that the UV central charges
should not be too large relative to certain parameters in the theory.


title: Derivative estimates of solutions of elliptic systems in narrow regions

abstract:
  We establish derivative estimates of solution of elliptic system in narrow
regions.


title:
Gradient estimates for solutions of the Lam\'{e} system with partially
  infinite coefficients

abstract:
  We establish upper bounds on the blow up rate of the gradients of solutions
of the Lam\'e system with partially infinite coefficients in dimension two as
the distance between the surfaces of discontinuity of the coefficients of the
system tends to zero.


title: Face Recognition via Globality-Locality Preserving Projections

abstract:
  We present an improved Locality Preserving Projections (LPP) method, named
Gloablity-Locality Preserving Projections (GLPP), to preserve both the global
and local geometric structures of data. In our approach, an additional
constraint of the geometry of classes is imposed to the objective function of
conventional LPP for respecting some more global manifold structures. Moreover,
we formulate a two-dimensional extension of GLPP (2D-GLPP) as an example to
show how to extend GLPP with some other statistical techniques. We apply our
works to face recognition on four popular face databases, namely ORL, Yale,
FERET and LFW-A databases, and extensive experimental results demonstrate that
the considered global manifold information can significantly improve the
performance of LPP and the proposed face recognition methods outperform the
state-of-the-arts.


title:
Superconductivity in Ca10(Ir4As8)(Fe2As2)5 with Square-Planar
  Coordination of Iridium

abstract:
  We report the unprecedented square-planar coordination of iridium in the iron
iridium arsenide Ca10(Ir4As8)(Fe2As2)5. This material experiences
superconductivity at 16 K. X-ray photoemission spectroscopy and first-
principles band calculation suggest Ir(II) oxidation state, which yields
electrically conductive Ir4As8 layers. Such metallic spacer layers are thought
to enhance the interlayer coupling of Fe2As2, in which superconductivity
emerges, thus offering a way to control the superconducting transition
temperature.


title: Analytic toy-model for the ISCO shift

abstract:
  A simple black-hole-ring system is proposed as a toy model for the two-body
problem in general relativity. This toy-model yields the fractional shift
$\Delta\Omega_{\text{isco}}/\Omega_{\text{isco}}={{29}\over{81\sqrt{2}}}\eta$
in the Schwarzschild ISCO (innermost stable circular orbit) frequency, where
$\eta\equiv m/M_{\text{ir}}\ll 1$ is the dimensionless ratio between the mass
of the particle and the irreducible mass of the black hole. Our model suggests
that the second-order spin-orbit interaction between the black hole and the
orbiting particle (the dragging of inertial frames) is the main element
determining the observed value of the ISCO shift.


title:
Non-Markovian Dynamics Impact on the Foundations of Statistical
  Mechanics

abstract:
  The foundations of statistical mechanics, namely how equilibrium hypothesis
emerges microscopically from quantum theory, is explored through investigating
the environment-induced quantum decoherence processes. Based on the recent
results on non-Markovian dynamics [Phys. Rev. Lett. 109, 170402 (2012)], we
find that decoherence of quantum states manifests unexpected complexities.
Indeed, an arbitrary given initial quantum state, under the influence of
different reservoirs, can evolve into four different steady states: thermal,
thermal-like, quantum memory and oscillating quantum memory states. The first
two steady states \textit{de facto} provided a rigorous proof how the system
relaxes to thermal equilibrium with its environment. The latter two steady
states, with strong non-Markovian effects, will maintain the initial state
information and not reach thermal equilibrium, which is beyond the conventional
wisdom of statistical mechanics.


title: Variable Selection in Causal Inference Using Penalization

abstract:
  In the causal adjustment setting, variable selection techniques based on
either the outcome or treatment allocation model can result in the omission of
confounders or the inclusion of spurious variables in the propensity score. We
propose a variable selection method based on a penalized likelihood which
considers the response and treatment assignment models simultaneously. The
proposed method facilitates confounder selection in high-dimensional settings.
We show that under some conditions our method attains the oracle property. The
selected variables are used to form a double robust regression estimator of the
treatment effect. Simulation results are presented and economic growth data are
analyzed.


title: On the existence of an energy gap in one-dimensional Lesanovsky's model

abstract:
  We study the quantum lattice gas model in one dimension introduced by
Lesanovsky, who showed that the exact ground state and a couple of excited
states can be obtained analytically. The Hamiltonian of the model depends
solely on the parameter $z$, the meaning of which is a fugacity in the
corresponding classical lattice gas model. For small $z$ ($0<z<1$), we prove
that there is an energy gap between the ground state and the excited states by
applying Knabe's method.


title:
Minimal energy cost of thermodynamic information processes only with
  entanglement transfer

abstract:
  We present the minimal energy costs for the measurement and the information
erase, using only the Helmholtz free energy and the entanglement of formation.
The entanglement of formation appears in the form of difference which indicates
the amount of entanglement transfer on the memory during the processes; the
cost of the measurement is given by the entanglement gain, whereas the cost of
the information erase is given by the loss of available entanglement. Putting
together the present Letter and Rev. E 88, 042143 (2013), we can describe the
violation and the restoration of the second law only in terms of the
entanglement of formation; both of the excess of extracted work from
thermodynamics with information process over the conventional second law and
the total cost of the information process are given by the entanglement of
formation, and the former is less than or equal to the latter.


title:
Impact of Higher Harmonics in Searching for Gravitational Waves from
  Non-Spinning Binary Black Holes

abstract:
  Current searches for gravitational waves from coalescing binary black holes
(BBH) use templates that only include the dominant harmonic. In this study we
use effective-one-body multipolar waveforms calibrated to numerical-relativity
simulations to quantify the effect of neglecting sub-dominant harmonics on the
sensitivity of searches. We consider both signal-to-noise ratio (SNR) and the
signal-based vetoes that are used to re-weight SNR. We find that neglecting
sub-dominant modes when searching for non-spinning BBHs with component masses
$3\,M_{\odot} \leq m_1, m_2 \leq 200\,M_{\odot}$ and total mass $M <
360\,M_{\odot}$ in advanced LIGO results in a negligible reduction of the
re-weighted SNR at detection thresholds. Sub-dominant modes therefore have no
effect on the detection rates predicted for advanced LIGO. Furthermore, we find
that if sub-dominant modes are included in templates the sensitivity of the
search becomes worse if we use current search priors, due to an increase in
false alarm probability. Templates would need to be weighted differently than
what is currently done to compensate for the increase in false alarms. If we
split the template bank such that sub-dominant modes are only used when $M
\gtrsim 100\,M_{\odot}$ and mass ratio $q \gtrsim 4$, we find that the
sensitivity does improve for these intermediate mass-ratio BBHs, but the
sensitive volume associated with these systems is still small compared to
equal-mass systems. Using sub-dominant modes is therefore unlikely to
substantially increase the probability of detecting gravitational waves from
non-spinning BBH signals unless there is a relatively large population of
intermediate mass-ratio BBHs in the universe.


title:
Determining the mass anomalous dimension through the eigenmodes of Dirac
  operator

abstract:
  We define a scale-dependent effective mass anomalous dimension from the
scaling of the mode number of the massless Dirac operator, which connects the
perturbative $\gamma_m$ of an asymptotically-free system to the universal
$\gamma_m^{\star}$ at a conformal fixed point. We use a stochastic algorithm to
measure the mode number up to the cutoff scale on lattices as large as $48^4$.
Focusing on SU(3) lattice gauge theory with $N_f = 12$ massless fundamental
fermions, we examine systematic effects due to finite volumes and non-zero
fermion masses. Our results suggest the existence of an infrared fixed point
with $\gamma_m^{\star} \approx 0.25$. Our method provides a unique probe to
study systems from the UV to the IR. It is universal and can be applied to any
lattice model of interest, including both chirally-broken and IR-conformal
systems.


title: Performance of Uplink Multiuser Massive MIMO Systems

abstract:
  We study the performance of uplink transmission in a large-scale (massive)
MIMO system, where all the transmitters have single antennas and the receiver
(base station) has a large number of antennas. Specifically, we analyze
achievable degrees of freedom of the system without assuming channel state
information at the receiver. Also, we quantify the amount of power saving that
is possible with increasing number of receive antennas.


title:
On a certain nilpotent extension over Q of degree 64 and the 4-th
  multiple residue symbol

abstract:
  In this paper, we introduce the 4-th multiple residue symbol $[p_1, p_2, p_3,
p_4]$ for certain four prime numbers $p_1, p_2, p_3, p_4$, which extends the
Legendre symbol and the R\'{e}dei triple symbol in a natural manner. For this
we construct concretely a certain nilpotent extension K over Q of degree 64,
where ramified prime numbers are $p_1$, $p_2$ and $p_3$, such that the symbol
$[p_1, p_2, p_3, p_4]$ describes the decomposition law of $p_4$ in the
extension K/Q. We then establish the relation of our symbol and the 4-th
arithmetic Milnor invariant (an arithmetic analogue of the 4-th order linking
number).


title:
Magic polarization for optical trapping of atoms without Stark-induced
  dephasing

abstract:
  We demonstrate that the differential ac-Stark shift of a ground-state
hyperfine transition in an optical trap can be eliminated by using properly
polarized trapping light. We use the vector polarizability of an alkali-metal
atom to produce a polarization-dependent ac-Stark shift that resembles a Zeeman
shift. We study a transition from the |2S1/2,F=2,mF=-2> to the
|2S1/2,F=1,mF=-1> state of 7Li to observe 0.59+-0.02 Hz linewidth with
interrogation time of 2 s and 0.82+-0.06 s coherence time of a superposition
state. Implications of the narrow linewidth and the long coherence time for
precision spectroscopy and quantum information processing using atoms in an
optical lattice are discussed.


title: Multiuser SM-MIMO versus Massive MIMO: Uplink Performance Comparison

abstract:
  In this paper, we propose algorithms for signal detection in large-scale
multiuser {\em spatial modulation multiple-input multiple-output (SM-MIMO)}
systems. In large-scale SM-MIMO, each user is equipped with multiple transmit
antennas (e.g., 2 or 4 antennas) but only one transmit RF chain, and the base
station (BS) is equipped with tens to hundreds of (e.g., 128) receive antennas.
In SM-MIMO, in a given channel use, each user activates any one of its multiple
transmit antennas and the index of the activated antenna conveys information
bits in addition to the information bits conveyed through conventional
modulation symbols (e.g., QAM). We propose two different algorithms for
detection of large-scale SM-MIMO signals at the BS; one is based on {\em
message passing} and the other is based on {\em local search}. The proposed
algorithms are shown to achieve very good performance and scale well. Also, for
the same spectral efficiency, multiuser SM-MIMO outperforms conventional
multiuser MIMO (recently being referred to as massive MIMO) by several dBs; for
e.g., with 16 users, 128 antennas at the BS and 4 bpcu per user, SM-MIMO with 4
transmit antennas per user and 4-QAM outperforms massive MIMO with 1 transmit
antenna per user and 16-QAM by about 4 to 5 dB at $10^{-3}$ uncoded BER. The
SNR advantage of SM-MIMO over massive MIMO can be attributed to the following
reasons: (i) because of the spatial index bits, SM-MIMO can use a lower-order
QAM alphabet compared to that in massive MIMO to achieve the same spectral
efficiency, and (ii) for the same spectral efficiency and QAM size, massive
MIMO will need more spatial streams per user which leads to increased spatial
interference.


title: A Generalized Savage-Dickey Ratio

abstract:
  In this brief research note I present a generalized version of the
Savage-Dickey Density Ratio for representation of the Bayes factor (or marginal
likelihood ratio) of nested statistical models; the new version takes the form
of a Radon-Nikodym derivative and is thus applicable to a wider family of
probability spaces than the original (restricted to those admitting an ordinary
Lebesgue density). A derivation is given following the measure-theoretic
construction of Marin & Robert (2010), and the equivalent estimator is
demonstrated in application to a distributional modeling problem.


title:
Short-Term Variability of X-rays from Accreting Neutron Star Vela X-1:
  II. Monte-Carlo Modeling

abstract:
  We develop a Monte Carlo Comptonization model for the X-ray spectrum of
accretion-powered pulsars. Simple, spherical, thermal Comptonization models
give harder spectra for higher optical depth, while the observational data from
Vela X-1 show that the spectra are harder at higher luminosity. This suggests a
physical interpretation where the optical depth of the accreting plasma
increases with mass accretion rate. We develop a detailed Monte-Carlo model of
the accretion flow, including the effects of the strong magnetic field ($\sim
10^{12}$ G) both in geometrically constraining the flow into an accretion
column, and in reducing the cross section. We treat bulk-motion Comptonization
of the infalling material as well as thermal Comptonization. These model
spectra can match the observed broad-band {\it Suzaku} data from Vela X-1 over
a wide range of mass accretion rates. The model can also explain the so-called
"low state", in which the uminosity decreases by an order of magnitude. Here,
thermal Comptonization should be negligible, so the spectrum instead is
dominated by bulk-motion Comptonization.


title: Delay Learning Architectures for Memory and Classification

abstract:
  We present a neuromorphic spiking neural network, the DELTRON, that can
remember and store patterns by changing the delays of every connection as
opposed to modifying the weights. The advantage of this architecture over
traditional weight based ones is simpler hardware implementation without
multipliers or digital-analog converters (DACs) as well as being suited to
time-based computing. The name is derived due to similarity in the learning
rule with an earlier architecture called Tempotron. The DELTRON can remember
more patterns than other delay-based networks by modifying a few delays to
remember the most 'salient' or synchronous part of every spike pattern. We
present simulations of memory capacity and classification ability of the
DELTRON for different random spatio-temporal spike patterns. The memory
capacity for noisy spike patterns and missing spikes are also shown. Finally,
we present SPICE simulation results of the core circuits involved in a
reconfigurable mixed signal implementation of this architecture.


title:
On the Subclasses in Swift Long Gamma-Ray Bursts: A Clue to Different
  Central Engines

abstract:
  Analyzing light curves of a complete sample of bright Swift long gamma-ray
bursts (LGRBs) of which the peak photon fluxes constructed with the bin width
of 1 second in the Swift 15-350 keV energy band exceed 2.6 photons
cm$^{-2}$s$^{-1}$, we confirm that there do exist the third class in GRBs in
addition to short and long GRBs. Being different from previous works based on
the duration, fluence, etc. our classification method is based on two
properties both quantified with light curve shapes of the prompt emission: the
Absolute Deviation from the Constant Luminosity of their cumulative light curve
$ADCL$, and the ratio of the mean counts to the maximum counts $\bar C/C_{\rm
max}$. These are independent of the distance and the jet opening angle. A
cluster analysis via the Gaussian mixture model detects three subclasses: one
consisting of LGRBs with small $ADCL$ and large $\bar C/C_{\rm max}$ values
referred to as Type I, one with large $ADCL$ and large $\bar C/C_{\rm max}$
referred to as Type II, and one with intermediate $ADCL$ and small $\bar
C/C_{\rm max}$, which is composed of contaminating short GRBs with the extended
emission. This result is reinforced by different temporal and spectral indices
of their X-ray afterglows. The difference is prominent in the temporal index of
the steep decay phase in particular: the indices for Type I LGRBs distribute
between $-6$ and $-3$ while those for Type II LGRBs between $-3$ and $-2$. From
these properties, we propose a possible scenario with different central
engines: an accreting black hole and a magnetar.


title: The algebraic structure of finite metabelian group algebras

abstract:
  An algorithm for the explicit computation of a complete set of primitive
central idempotents, Wedderburn decomposition and the automorphism group of the
semisimple group algebra of a finite metabelian group is developed. The
algorithm is illustrated with its application to the semisimple group algebra
of an arbitrary metacyclic group, and certain indecomposable groups whose
central quotient is the Klein four-group.


title:
Inhomogeneities, loop quantum gravity corrections, constraint algebra
  and general covariance

abstract:
  Loop quantum gravity corrections, in the presence of inhomogeneities, can
lead to a deformed constraint algebra. Such a deformation implies that the
effective theory is no longer generally covariant. As a consequence, the
geometrical concepts used in the classical theory lose their meaning. In the
present paper we propose a method, based on canonical transformation on the
phase space of the spherically symmetric effective theory, to systematically
recover the classical constraint algebra in the presence of the inverse triad
corrections as well as in the presence of the holonomy corrections. We show, by
way of explicit example, that this also leads to the recovery of general
covariance of the theory in the presence of inverse triad corrections, implying
that one can once again use the geometrical concepts to analyze the solutions
in the presence of these quantum gravity corrections.


title: Algorithmic and Hardness Results for the Colorful Components Problems

abstract:
  In this paper we investigate the colorful components framework, motivated by
applications emerging from comparative genomics. The general goal is to remove
a collection of edges from an undirected vertex-colored graph $G$ such that in
the resulting graph $G'$ all the connected components are colorful (i.e., any
two vertices of the same color belong to different connected components). We
want $G'$ to optimize an objective function, the selection of this function
being specific to each problem in the framework.
  We analyze three objective functions, and thus, three different problems,
which are believed to be relevant for the biological applications: minimizing
the number of singleton vertices, maximizing the number of edges in the
transitive closure, and minimizing the number of connected components.
  Our main result is a polynomial time algorithm for the first problem. This
result disproves the conjecture of Zheng et al. that the problem is $ NP$-hard
(assuming $P \neq NP$). Then, we show that the second problem is $ APX$-hard,
thus proving and strengthening the conjecture of Zheng et al. that the problem
is $ NP$-hard. Finally, we show that the third problem does not admit
polynomial time approximation within a factor of $|V|^{1/14 - \epsilon}$ for
any $\epsilon > 0$, assuming $P \neq NP$ (or within a factor of $|V|^{1/2 -
\epsilon}$, assuming $ZPP \neq NP$).


title:
A Density Difference Based Analysis of Orbital--Dependent
  Exchange--Correlation Functionals

abstract:
  We present a density difference based analysis for a range of
orbital--dependent Kohn--Sham functionals. Results for atoms, some members of
the neon isoelectronic series and small molecules are reported and compared
with ab initio wave-function calculations. Particular attention is paid to the
quality of approximations to the exchange--only optimized effective potential
(OEP) approach: we consider both the Localized Hartree Fock as well as the
Krieger-Li-Iafrate methods. Analysis of density differences at the
exchange--only level reveals the impact the approximations have on the
resulting electronic densities. These differences are further quantified in
terms of the ground state energies, frontier orbital energy differences and
highest occupied orbital energies obtained. At the correlated level an OEP
approach based on a perturbative second--order correlation energy expression is
shown to deliver results comparable with those from traditional wave function
approaches, making it suitable for use as a benchmark against which to compare
standard density--functional approximations.


title: Cosmic Ray acceleration and Balmer emission from RCW 86 (G315.4-2.3)

abstract:
  Context. Observation of Balmer lines from the region around the forward shock
of supernova remnants (SNR) may provide valuable information on the shock
dynamics and the efficiency of particle acceleration at the shock.
  Aims. We calculated the Balmer line emission and the shape of the broad
Balmer line for parameter values suitable for SNR RCW 86 (G315.4-2.3) as a
function of the cosmic-ray (CR) acceleration efficiency and of the level of
thermal equilibration between electrons and protons behind the shock. This
calculation aims at using the width of the broad Balmer-line emission to infer
the CR acceleration efficiency in this remnant.
  Methods. We used the recently developed nonlinear theory of diffusive
shock-acceleration in the presence of neutrals. The semianalytical approach we
developed includes a description of magnetic field amplification as due to
resonant streaming instability, the dynamical reaction of accelerated particles
and the turbulent magnetic field on the shock, and all channels of interaction
between neutral hydrogen atoms and background ions that are relevant for the
shock dynamics.
  Results. We derive the CR acceleration efficiency in the SNR RCW 86 from the
Balmer emission. Since our calculation used recent measurements of the shock
proper motion, the results depend on the assumed distance to Earth. For a
distance of 2 kpc the measured width of the broad Balmer line is compatible
with the absence of CR acceleration. For a distance of 2.5 kpc, which is a
widely used value in current literature, a CR acceleration efficiency of 5-30%
is obtained, depending upon the electron-ion equilibration and the ionization
fraction upstream of the shock. By combining information on Balmer emission
with the measured value of the downstream electron temperature, we constrain
the CR acceleration efficiency to be ~20%.


title:
Prediction of residue-residue contacts from protein families using
  similarity kernels and least squares regularization

abstract:
  One of the most challenging and long-standing problems in computational
biology is the prediction of three-dimensional protein structure from amino
acid sequence. A promising approach to infer spatial proximity between residues
is the study of evolutionary covariance from multiple sequence alignments,
especially in light of recent algorithmic improvements and the fast growing
size of sequence databases. In this paper, we present a simple, fast and
accurate algorithm for the prediction of residue-residue contacts based on
regularized least squares. The basic assumption is that spatially proximal
residues in a protein coevolve to maintain the physicochemical complementarity
of the amino acids involved in the contact. Our regularized inversion of the
sample covariance matrix allows the computation of partial correlations between
pairs of residues, thereby removing the effect of spurious transitive
correlations. The method also accounts for low number of observations by means
of a regularization parameter that depends on the effective number of sequences
in the alignment. When tested on a set of protein families from Pfam, we found
the RLS algorithm to have performance comparable to state-of-the-art methods
for contact prediction, while at the same time being faster and conceptually
simpler.


title: Discovery of New Layered Iron Arsenide Superconductor (Ca,Pr)FeAs2

abstract:
  A new iron-based superconductor (Ca,Pr)FeAs2 was discovered. Plate-like
crystals of the new phase were obtained and crystal structure was investigated
by single-crystal X-ray diffraction analysis. The structure was identified as
the monoclinic system with space group P21/m, and is composed of two Ca(Pr)
planes, anti-fluorite Fe2As2 layers, and As2 zigzag chain layers. Plate-like
crystals composed of the new phase showed superconductivity with Tc ~20 K in
both magnetization and resistivity measurements.


title:
Superconductivity in Ca1-xLaxFeAs2: A Novel 112-Type Iron Pnictide with
  Arsenic Zigzag Bonds

abstract:
  We report superconductivity in the novel 112-type iron-based compound
Ca1-xLaxFeAs2. Single-crystal X-ray diffraction analysis revealed that the
compound crystallizes in a monoclinic structure (space group P21), in which
Fe2As2 layers alternate with Ca2As2 spacer layers such that monovalent arsenic
forms zigzag chains. Superconductivity with a transition temperature (Tc) of 34
K was observed for the x = 0.1 sample, while the x = 0.21 sample exhibited
trace superconductivity at 45 K. First-principles band calculations
demonstrated the presence of almost cylindrical Fermi surfaces, favorable for
the high Tc in La-doped CaFeAs2.


title:
The synthesis and characterization of 1111-type diluted magnetic
  semiconductors (La1-xSrx)(Zn1-xTMx)AsO (TM = Mn, Fe, Co)

abstract:
  The doping effect of Sr and transition metals Mn, Fe, Co into the direct-gap
semiconductor LaZnAsO has been investigated. Our results indicate that the
single phase ZrCuSiAs-type tetragonal crystal structure is preserved in
(La1-xSrx)(Zn1-xTMx)AsO (TM = Mn, Fe, Co) with the doping level up to x = 0.1.
While the system remains semiconducting, doping with Sr and Mn results in
ferromagnetic order with TC ~ 30K, and doping with Sr and Fe results in a spin
glass like state below ~6K with a saturation moment of ~0.02 muB/Fe, an order
of magnitude smaller than the ~0.4 muB/Mn of Sr and Mn doped samples. The same
type of magnetic state is observed neither for (Zn,Fe) substitution without
carrier doping, nor for Sr and Co doped specimens.


title: The incidence of obscuration in active galactic nuclei

abstract:
  We study the incidence of nuclear obscuration on a complete sample of 1310
AGN selected on the basis of their rest-frame 2-10 keV X-ray flux from the
XMM-COSMOS survey, in the redshift range 0.3<z<3.5. We classify the AGN as
obscured or un-obscured on the basis of either the optical spectral properties
and the overall SED or the shape of the X-ray spectrum. The two classifications
agree in about 70% of the objects, and the remaining 30% can be further
subdivided into two distinct classes: at low luminosities X-ray un-obscured AGN
do not always show signs of broad lines or blue/UV continuum emission in their
optical spectra, most likely due to galaxy dilution effects; at high
luminosities broad line AGN may have absorbed X-ray spectra, which hints at an
increased incidence of small-scale (sub-parsec) dust-free obscuration. We
confirm that the fraction of obscured AGN is a decreasing function of the
intrinsic X-ray luminosity, while the incidence of absorption shows significant
evolution only for the most luminous AGN, which appear to be more commonly
obscured at higher redshift. We find no significant difference between the mean
stellar masses and star formation rates of obscured and un-obscured AGN hosts.
We conclude that the physical state of the medium responsible for obscuration
in AGN is complex, and mainly determined by the radiation environment (nuclear
luminosity) in a small region enclosed within the gravitational sphere of
influence of the central black hole, but is largely insensitive to the wider
scale galactic conditions.


title:
Microcanonical analysis of the Curie-Weiss anisotropic quantum
  Heisenberg model in a magnetic field

abstract:
  The anisotropic quantum Heisenberg model with Curie-Weiss-type interactions
is studied analytically in several variants of the microcanonical ensemble.
(Non)equivalence of microcanonical and canonical ensembles is investigated by
studying the concavity properties of entropies. The microcanonical entropy
s(e,m) is obtained as a function of the energy e and the magnetization vector m
in the thermodynamic limit. Since, for this model, e is uniquely determined by
m, the same information can be encoded either in s(m) or s(e,m1,m2). Although
these two entropies correspond to the same physical setting of fixed e and m,
their concavity properties differ. The entropy s_h(u), describing the model at
fixed total energy u and in a homogeneous external magnetic field h of
arbitrary direction, is obtained by reduction from the nonconcave entropy
s(e,m1,m2). In doing so, concavity, and therefore equivalence of ensembles, is
restored. s_h(u) has nonanalyticities on surfaces of co-dimension 1 in the
(u,h)-space. Projecting these surfaces into lower-dimensional phase diagrams,
we observe that the resulting phase transition lines are situated in the
positive-temperature region for some parameter values, and in the
negative-temperature region for others. In the canonical setting of a system
coupled to a heat bath of positive temperatures, the nonanalyticities in the
microcanonical negative-temperature region cannot be observed, and this leads
to a situation of effective nonequivalence even when formal equivalence holds.


title: Cones over metric measure spaces and the maximal diameter theorem

abstract:
  The main result of this article states that the (K;N)-cone over some metric
measure space satisfies the reduced Riemannian curvature-dimension condition
RCD^*(KN;N+1) if and only if the underlying space satisfies RCD^*(N-1;N). The
proof uses a characterization of reduced Riemannian curvature-dimension bounds
by Bochner's inequality that was established for metric measure spaces by
Erbar, Kuwada and Sturm and independently by Ambrosio, Mondino and Savar\'e. As
corollary of our result and the Cheeger-Gigli-Gromoll splitting theorem we
obtain a maximal diameter theorem for metric measure spaces that satisfy a
reduced Riemannian curvature-dimension condition.


title: Investigation of cosmic ray-cloud connections using MISR

abstract:
  Numerous empirical studies have analyzed International Satellite Cloud
Climatology Project data and reached contradictory conclusions regarding the
influence of solar-modulated galactic cosmic rays on cloud fraction and cloud
properties. The Multiangle Imaging Spectroradiometer (MISR) instrument on the
Terra satellite has been in continuous operation for 13 years and thus provides
an independent (and previously unutilized) cloud data set to investigate
purported solar-cloud links. Furthermore, unlike many previous solar-climate
studies that report cloud fraction MISR measures albedo, which has clearer
climatological relevance. Our long-term analysis of MISR data finds no
statistically significant correlations between cosmic rays and global albedo or
globally averaged cloud height, and no evidence for any regional or lagged
correlations. Moreover, epoch superposition analysis of Forbush decreases
reveals no detectable albedo response to cosmic ray decreases, thereby placing
an upper limit on the possible influence of cosmic ray variations on global
albedo of 0.0029 per 5% decrease. The implications for recent global warming
are discussed.


title:
Convex lifted conditions for robust stability analysis and stabilization
  of linear discrete-time switched systems

abstract:
  Stability analysis of discrete-time switched systems under minimum dwell-time
is studied using a new type of LMI conditions. These conditions are convex in
the matrices of the system and shown to be equivalent to the nonconvex
conditions proposed by Geromel and Colaneri. The convexification of the
conditions is performed by a lifting process which introduces a moderate number
of additional decision variables. The convexity of the conditions can be
exploited to extend the results to uncertain systems, control design and
$\ell_2$-gain computation without introducing additional conservatism. Several
examples are presented to show the effectiveness of the approach.


title: Central theorems for cohomologies of certain solvable groups

abstract:
  We show that the group cohomology of torsion-free virtually polycyclic groups
and the continuous cohomology of simply connected solvable Lie groups can be
computed by the rational cohomology of algebraic groups. Our results are
generalizations of certian results on the cohomology of solvmanifolds and
infra-solvmanifolds. Moreover as an application of our results, we give a
simple proof of the surprising cohomology vanishing theorem given by
Dekimpe-Igodt.


title:
Galaxies with Supermassive Binary Black Holes: (I) A Possible Model for
  the Centers of Core Galaxies

abstract:
  The dynamics of galactic systems with central binary black holes is studied.
The model is a modification from the restricted three body problem, in which a
galactic potential is added as an external potential. Considering the case with
an equal mass binary black holes, the conditions of existence of equilibrium
points, including Lagrange Points and additional new equilibrium points, i.e.
Jiang-Yeh Points, are investigated. A critical mass is discovered to be
fundamentally important. That is, Jiang-Yeh Points exist if and only if the
galactic mass is larger than the critical mass. The stability analysis is
performed for all equilibrium points. The results that Jiang-Yeh Points are
unstable could lead to the core formation in the centers of galaxies.


title:
Two are Better Than One: Adaptive Sparse System Identification using
  Affine Combination of Two Sparse Adaptive Filters

abstract:
  Sparse system identification problems often exist in many applications, such
as echo interference cancellation, sparse channel estimation, and adaptive
beamforming. One of popular adaptive sparse system identification (ASSI)
methods is adopting only one sparse least mean square (LMS) filter. However,
the adoption of only one sparse LMS filter cannot simultaneously achieve fast
convergence speed and small steady-state mean state deviation (MSD). Unlike the
conventional method, we propose an improved ASSI method using affine
combination of two sparse LMS filters to simultaneously achieving fast
convergence and low steady-state MSD. First, problem formulation and standard
affine combination of LMS filters are introduced. Then an approximate optimum
affine combiner is adopted for the proposed filter according to stochastic
gradient search method. Later, to verify the proposed filter for ASSI, computer
simulations are provided to confirm effectiveness of the proposed filter which
can achieve better estimation performance than the conventional one and
standard affine combination of LMS filters.


title:
Chiral phase transition with mixing between scalar quarkonium and
  tetraquark

abstract:
  In the framework of two-flavor extended linear sigma model with mixing
between scalar quarkonium and tetraquark, we investigate the role of the
tetraquark in the chiral phase transition. We explore various scenarios
depending on the value of various parameters in our model. The physical mass
spectrum of mesons put a tight constraint on the parameter set of our model. We
find a sufficiently strong cubic self interaction of the tetraquark field can
drive the chiral phase transition to first order even at zero quark chemical
potential. Weak or absence of the cubic self interaction term of the tetraquark
field make the chiral phase transition crossover at vanishing density.


title:
Variable is Better Than Invariable: Stable Sparse VSS-NLMS Algorithms
  with Application to Estimating MIMO Channels

abstract:
  To estimate multiple-input multiple-output (MIMO) channels, invariable
step-size normalized least mean square (ISSNLMS) algorithm was applied to
adaptive channel estimation (ACE). Since the MIMO channel is often described by
sparse channel model due to broadband signal transmission, such sparsity can be
exploited by adaptive sparse channel estimation (ASCE) methods using sparse
ISS-NLMS algorithms. It is well known that step-size is a critical parameter
which controls three aspects: algorithm stability, estimation performance and
computational cost. The previous approaches can exploit channel sparsity but
their step-sizes are keeping invariant which unable balances well the three
aspects and easily cause either estimation performance loss or instability. In
this paper, we propose two stable sparse variable step-size NLMS (VSS-NLMS)
algorithms to improve the accuracy of MIMO channel estimators. First, ASCE for
estimating MIMO channels is formulated in MIMO systems. Second, different
sparse penalties are introduced to VSS-NLMS algorithm for ASCE. In addition,
difference between sparse ISS-NLMS algorithms and sparse VSS-NLMS ones are
explained. At last, to verify the effectiveness of the proposed algorithms for
ASCE, several selected simulation results are shown to prove that the proposed
sparse VSS-NLMS algorithms can achieve better estimation performance than the
conventional methods via mean square error (MSE) and bit error rate (BER)
metrics.


title:
Variable Earns Profit: Improved Adaptive Channel Estimation using Sparse
  VSS-NLMS Algorithms

abstract:
  Accurate channel estimation is essential for broadband wireless
communications. As wireless channels often exhibit sparse structure, the
adaptive sparse channel estimation algorithms based on normalized least mean
square (NLMS) have been proposed, e.g., the zero-attracting NLMS (ZA-NLMS)
algorithm and reweighted zero-attracting NLMS (RZA-NLMS). In these NLMS-based
algorithms, the step size used to iteratively update the channel estimate is a
critical parameter to control the estimation accuracy and the convergence speed
(so the computational cost). However, invariable step-size (ISS) is usually
used in conventional algorithms, which leads to provide performance loss or/and
low convergence speed as well as high computational cost. To solve these
problems, based on the observation that large step size is preferred for fast
convergence while small step size is preferred for accurate estimation, we
propose to replace the ISS by variable step size (VSS) in conventional
NLMS-based algorithms to improve the adaptive sparse channel estimation in
terms of bit error rate (BER) and mean square error (MSE) metrics. The proposed
VSS-ZA-NLMS and VSS-RZA-NLMS algorithms adopt VSS, which can be adaptive to the
estimation error in each iteration, i.e., large step size is used in the case
of large estimation error to accelerate the convergence speed, while small step
size is used when the estimation error is small to improve the steady-state
estimation accuracy. Simulation results are provided to validate the
effectiveness of the proposed scheme.


title:
Computational study of structural, electronic and optical properties of
  crystalline NH$_4$N$_3$

abstract:
  A systematic computational study on the structural, electronic, bonding, and
optical properties of orthorhombic ammonium azide (NH$_4$N$_3$) has been
performed using planewave pseudopotential (PW-PP) method based on density
functional theory (DFT). Semiempirical dispersion correction schemes have been
used to account for non-bonded interactions in molecular crystalline
NH$_4$N$_3$. The ground state lattice parameters and fractional co-ordinates
obtained using the dispersion correction schemes are in excellent agreement
with experimental results. We calculated the single crystal elastic constants
of NH$_4$N$_3$ and its sensitivity is interpreted through the observed ordering
of the elastic constants (C$_{33}$ $>$ C$_{11}$ $>$ C$_{22}$). The electronic
structure and optical properties were calculated using full potential
linearized augmented plane wave (FP-LAPW) approach with recently developed
functional of Tran-Blaha modified Becke-Johnson (TB-mBJ) potential. The TB-mBJ
electronic structure shows that NH$_4$N$_3$ is a direct band gap insulator with
a band gap of 5.08 eV, while the calculated band gap with standard generalized
gradient approximation is found to be 4.10 eV. The optical anisotropy is
analyzed through the calculated optical constants namely dielectric function
and refractive index along three different crystallographic axes. The
absorption spectra reveal that NH$_4$N$_3$ is sensitive to ultraviolet (UV)
light. Further, we also analyzed the detonation characteristics of the
NH$_4$N$_3$ using the reported heat of formation and calculated density.
NH$_4$N$_3$ is found to have a detonation velocity of 6.45 km/s and a
detonation pressure about 15.16 GPa computed by Kamlet-Jacobs empirical
equations.


title: Supersymmetric B-L inflation near the conformal coupling

abstract:
  We investigate a novel scenario of cosmological inflation in a gauged $B-L$
extended minimal supersymmetric Standard Model with R-symmetry. We use a
noncanonical K\"{a}hler potential and a superpotential, both preserving the
R-symmetry to construct a model of slow-roll inflation. The model is controlled
by two real parameters: the nonminimal coupling $\xi$ that originates from the
K\"{a}hler potential, and the breaking scale $v$ of the $U(1)_{B-L}$ symmetry.
We compute the spectrum of the cosmological microwave background radiation and
show that the prediction of the model fits well the recent Planck satellite
observation for a wide range of the parameter space. We also find that the
typical reheating temperature of the model is low enough to avoid the gravitino
problem but nevertheless allows sufficient production of the baryon asymmetry
if we take into account the effect of resonance enhancement. The model is free
from cosmic strings that impose stringent constraints on generic $U(1)_{B-L}$
based scenarios, as in our scenario the $U(1)_{B-L}$ symmetry is broken from
the onset.


title:
Same universality class for the critical behavior in and out of
  equilibrium in a quenched random field

abstract:
  The random-field Ising model (RFIM) is one of the simplest
statistical-mechanical models that captures the anomalous irreversible
collective response seen in a wide range of physical, biological, or
socio-economic situations in the presence of interactions and intrinsic
heterogeneity or disorder. When slowly driven at zero temperature it can
display an out-of-equilibrium phase transition associated with critical scaling
("crackling noise"), while it undergoes at equilibrium, under either
temperature or disorder-strength changes, a thermodynamic phase transition. We
show that the out-of-equilibrium and equilibrium critical behaviors are in the
same universality class: they are controlled, in the renormalization-group (RG)
sense, by the same zero-temperature fixed point. We do so by combining a
field-theoretical formalism that accounts for the multiple metastable states
and the exact (functional) RG. As a spin-off, we also demonstrate that critical
fluids in disordered porous media are in the same universality class as the
RFIM, thereby unifying a broad spectrum of equilibrium and out-of-equilibrium
phenomena.


title:
Weak lensing mass map and peak statistics in Canada-France-Hawaii
  Telescope Stripe 82 survey

abstract:
  We present a weak lensing mass map covering ~124 square degrees of the
Canada-France-Hawaii Telescope Stripe 82 Survey (CS82). We study the statistics
of rare peaks in the map, including peak abundance, the peak-peak correlation
functions and the tangential-shear profiles around peaks. We find that the
abundance of peaks detected in CS82 is consistent with predictions from a
Lambda-CDM cosmological model, once noise effects are properly included. The
correlation functions of peaks with different signal-to-noise ratio (SNR) are
well described by power laws, and there is a clear cross-correlation between
the Sloan Digital Sky Survey III/Constant Mass galaxies and high SNR peaks. The
tangential-shear profiles around peaks increase with peak SNR. We fit
analytical models to the tangential-shear profiles, including a projected
singular isothermal sphere (SIS) model and a projected Navarro, Frenk & White
(NFW) model, plus a two-halo term. For the high SNR peaks, the SIS model is
rejected at ~3-sigma. The NFW model plus a two-halo term gives more acceptable
fits to the data. Some peaks match the positions of optically detected
clusters, while others are relatively dark. Comparing dark and matched peaks,
we find a difference in lensing signal of a factor of 2, suggesting that about
half of the dark peaks are false detections.


title: Exact solutions to relativistic singular fractional power potentials

abstract:
  We present (exact) solutions of the Dirac equation with equally mixed
interactions for a single fermion bounded by the family of fractional power
singular potentials. Closed-form expressions as well as numerical values for
the energies were obtained. The wave functions and the allowed values of the
potential parameters for the first two members of the family are obtained in
terms of a set of algebraic equations. The non relativistic limit is also
discussed and using the Hellmann-Feynmann theorem, some useful expectation
values are obtained.


title: Nonlinear Response in the Driven Lattice Lorentz Gas

abstract:
  We determine the nonlinear time-dependent response of a tracer on a lattice
with randomly distributed hard obstacles as a force is switched on. The
calculation is exact to first order in the obstacle density and holds for
arbitrarily large forces. Whereas, on the impurity-free lattice, the nonlinear
drift velocity in the stationary state is analytic in the driving force,
interactions with impurities introduce logarithmic contributions beyond the
linear regime. The long-time decay of the velocity toward the steady state is
exponentially fast for any finite value of the force, in striking contrast to
the power-law relaxation predicted within linear response. We discuss the range
of validity of our analytic results by comparison to stochastic simulations.


title:
Modelling Families of Business Process Variants: A Decomposition Driven
  Method

abstract:
  Business processes usually do not exist as singular entities that can be
managed in isolation, but rather as families of business process variants. When
modelling such families of variants, analysts are confronted with the choice
between modelling each variant separately, or modelling multiple or all
variants in a single model. Modelling each variant separately leads to a
proliferation of models that share common parts, resulting in redundancies and
inconsistencies. Meanwhile, modelling all variants together leads to less but
more complex models, thus hindering on comprehensibility. This paper introduces
a method for modelling families of process variants that addresses this
trade-off. The key tenet of the method is to alternate between steps of
decomposition (breaking down processes into sub-processes) and deciding which
parts should be modelled together and which ones should be modelled separately.
We have applied the method to two case studies: one concerning the
consolidation of ex-isting process models, and another dealing with green-field
process discovery. In both cases, the method produced fewer models with respect
to the baseline and reduced duplicity by up to 50% without significant impact
on complexity.


title:
How Does Kanban Impact Communication and Collaboration in Software
  Engineering Teams?

abstract:
  Highly iterative development processes such as Kanban have gained significant
importance in industry. However, the impact of such processes on team
collaboration and communication is widely unknown. In this paper, we analyze
how the Kanban process aids software team's behaviours -- in particular,
communication and collaboration. The team under study developed a mobile
payment software product in six iterations over seven weeks. The data were
collected by a questionnaire, repeated at the end of each iteration. The
results indicate that Kanban has a positive effect at the beginning to get the
team working together to identify and coordinate the work. Later phases, when
the team members have established good rapport among them, the importance for
facilitating team collaboration could not be shown. Results also indicate that
Kanban helps team members to collectively identify and surface the missing
tasks to keep the pace of the development harmonized across the whole team,
resulting into increased collaboration. Besides presenting the study and the
results, the article gives an outlook on future work.


title:
Anomalous effective action, Noether current, Virasoro algebra and
  Horizon entropy

abstract:
  Several investigations show that in a very small length scale there exists
corrections to the entropy of black hole horizon. Due to fluctuations of the
background metric and the external fields the action incorporates corrections.
In the low energy regime, the one loop effective action in four dimensions
leads to trace anomaly. We start from the Noether current corresponding to the
Einstein-Hilbert plus the one loop effective action to calculate the charge for
the diffeomorphisms which preserve the Killing horizon structure. Then a
bracket among the charges is calculated. We show that the Fourier modes of the
bracket is exactly similar to Virasoro algebra. Then using Cardy formula the
entropy is evaluated. Finally, the explicit terms of the entropy expression is
calculated for a classical background. It turns out that the usual expression
for entropy; i.e. the Bekenstein-Hawking form, is not modified.


title: $q\bar{q}$-potential: a numerical study

abstract:
  We report the results of recent lattice simulations aimed at computing the
$q$ and $\bar q$ potential energies in the singlet and the octet (adjoint)
representation.


title: Evaporating black holes have leaky horizons or exotic atmospheres

abstract:
  Classically, black holes are compact objects with perfect semi-permeable
horizons: Anything may enter, nothing may leave. We consider an axiomatic
approach that applies to any black hole type, including arbitrarily
near-extremal black holes, that can unitarily evaporate away completely by any
mechanism. We show that a quantum black hole must either have a leaky horizon
(allowing quantum information out), or it must look very different from its
classical counterpart having an external neighborhood consisting of exotic
matter with super-ordinary entropic content (such as an `atmosphere' of
microscopic black holes).


title:
Limit theorems for strongly and intermediately supercritical branching
  processes in random environment with linear fractional offspring
  distributions

abstract:
  In the present paper, we characterize the behavior of supercritical branching
processes in random environment with linear fractional offspring distributions,
conditioned on having small, but positive values at some large generation. As
it has been noticed in previous works, there is a phase transition in the
behavior of the process. Here, we examine the strongly and intermediately
supercritical regimes The main result is a conditional limit theorem for the
rescaled associated random walk in the intermediately case.


title:
ExoMol line lists III: An improved hot rotation-vibration line list for
  HCN and HNC

abstract:
  A revised rotation-vibration line list for the combined hydrogen cyanide
(HCN) / hydrogen isocyanide (HNC) system is presented. The line list uses {\it
ab initio} transition intensities calculated previously (Harris et al., ApJ,
2002, 578, 657) and extensive datasets of recently measured experimental energy
levels (Mellau, J. Chem. Phys. and J. Mol. Spectrosc. 2010-2011). The resulting
line list has significantly more accurate wavelengths than previous ones for
these systems. An improved value for the separation between HCN and HNC is
adopted leading to an approximately 25%\ lower predicted thermal population of
HNC as a function of temperature in the key 2000 to 3000 K region.
Temperature-dependent partition functions and equilibrium constants are
presented. The line lists are validated by comparison with laboratory spectra
and are presented in full as supplementary data to the article and at
\url{www.exomol.com}.


title:
Physical Layer Network Coding: A Cautionary Story with Interference and
  Spatial Reservation

abstract:
  Physical layer network coding (PLNC) has the potential to improve throughput
of multi-hop networks. However, most of the works are focused on the simple,
three-node model with two-way relaying, not taking into account the fact that
there can be other neighboring nodes that can cause/receive interference. The
way to deal with this problem in distributed wireless networks is usage of
MAC-layer mechanisms that make a spatial reservation of the shared wireless
medium, similar to the well-known RTS/CTS in IEEE 802.11 wireless networks. In
this paper, we investigate two-way relaying in presence of interfering nodes
and usage of spatial reservation mechanisms. Specifically, we introduce a
reserved area in order to protect the nodes involved in two-way relaying from
the interference caused by neighboring nodes. We analytically derive the
end-to-end rate achieved by PLNC considering the impact of interference and
reserved area. A relevant performance measure is data rate per unit area, in
order to reflect the fact that any spatial reservation blocks another data
exchange in the reserved area. The numerical results carry a cautionary message
that the gains brought by PLNC over one-way relaying may be vanishing when the
two-way relaying is considered in a broader context of a larger wireless
network.


title:
Stark broadening of B IV lines for astrophysical and laboratory plasma
  research

abstract:
  Stark broadening parameters for 36 multiplets of B IV have been calculated
using the semi-classical perturbation formalism. Obtained results have been
used to investigate the regularities within spectral series and temperature
dependence.


title: Lipschitz continuity of harmonic maps between Alexandrov spaces

abstract:
  In 1997, J. Jost [27] and F. H. Lin [39], independently proved that every
energy minimizing harmonic map from an Alexandrov space with curvature bounded
from below to an Alexandrov space with non-positive curvature is locally
H\"older continuous. In [39], F. H. Lin proposed a challenge problem: Can the
H\"older continuity be improved to Lipschitz continuity? J. Jost also asked a
similar problem about Lipschitz regularity of harmonic maps between singular
spaces (see Page 38 in [28]). The main theorem of this paper gives a complete
resolution to it.


title: The WFPC2 UV Survey: the BSS population in NGC 5824

abstract:
  We have used a combination of high-resolution Hubble Space Telescope WFPC2
and wide-field ground-based observations, in ultraviolet and optical bands, to
study the blue straggler star population of the massive outer-halo globular
cluster NGC 5824, over its entire radial extent. We have computed the center of
gravity of the cluster and constructed the radial density profile, from
detailed star counts. The profile is well reproduced by a Wilson model with a
small core (r_c \simeq 4.4 arcsec) and a concentration parameter c \simeq 2.74.
We also present the first age determination for this cluster. From the
comparison with isochrones, we have found t=13\pm0.5 Gyr. We discuss this
result in the context of the observed age-metallicity relation of Galactic
globular clusters. A total of 60 bright blue stragglers has been identified.
Their radial distribution is found to be bimodal, with a central peak, a well
defined minimum at r \sim 20 arcsec, and an upturn at large radii. In the
framework of the dynamical clock defined by Ferraro et al. (2012), this feature
suggests that NGC 5824 is a cluster of intermediate dynamical age.


title: A note on $k$-hyperreflexivity of Toeplitz-harmonic subspaces

abstract:
  The 2-hyperreflexivity of Toeplitz-harmonic type subspace generated by an
isometry or a quasinormal operator is shown. The $k$-hyperreflexivity of the
tensor product $\mathcal{S}\otimes \mathcal{V}$ of a $k$-hyperreflexive
decomposable subspace $\mathcal{S}$ and an abelian von Neumann algebra
$\mathcal{V}$ is established.


title: Onboarding in Open Source Software Projects: A Preliminary Analysis

abstract:
  Nowadays, many software projects are partially or completely open-source
based. There is an increasing need for companies to participate in open-source
software (OSS) projects, e.g., in order to benefit from open source ecosystems.
OSS projects introduce particular challenges that have to be understood in
order to gain the benefits. One such challenge is getting newcomers onboard
into the projects effectively. Similar challenges may be present in other
self-organised, virtual team environments. In this paper we present preliminary
observations and results of in-progress research that studies the process of
onboarding into virtual OSS teams. The study is based on a program created and
conceived at Stanford University in conjunction with Facebook's Education
Modernization program. It involves the collaboration of more than a dozen
international universities and nine open source projects. More than 120
students participated in 2013. The students have been introduced to and
supported by mentors experienced in the participating OSS projects. Our
findings indicate that mentoring is an important factor for effective
onboarding in OSS projects, promoting cohesion within distributed teams and
maintaining an appropriate pace.


title: Sterile Neutrino Status

abstract:
  We review the results of global analyses of short-baseline neutrino
oscillation data in 3+1, 3+2 and 3+1+1 neutrino mixing schemes.


title:
Non-conventional superconducting fluctuations in Ba(Fe1-xRhx)2As2
  iron-based superconductors

abstract:
  We measured the static uniform spin susceptibility of
Ba(Fe$_{1-x}$Rh$_x$)$_2$As$_2$ iron-based superconductors, over a broad range
of doping ($0.041\leq x\leq 0.094$) and magnetic fields. At small fields ($H
\le$ 1 kOe) we observed, above the transition temperature $T_c$, the occurrence
of precursor diamagnetism, which is not ascribable to the Ginzburg-Landau
theory. On the contrary, our data fit a phase fluctuation model, which has been
used to interpret a similar phenomenology occurring in the high-$T_c$ cuprate
superconductors. On the other hand, in presence of strong fields the
unconventional fluctuating diamagnetism is suppressed, whereas 3D fluctuations
are found, in agreement with literature.


title:
Statistical complexity measures as telltale of relevant scales in
  emergent dynamics of spatial systems

abstract:
  The definition of complexity through Statistical Complexity Measures (SCM)
has recently seen major improvements. Mostly, effort is concentrated in
measures on time series. We propose a SCM definition for spatial dynamical
systems. Our definition is in line with the trend to combine entropy with
measures of structure (such as disequilibrium). We study the behaviour of our
definition against the vectorial noise model of Collective Motion. From a
global perspective, we show how our SCM is minimal at both the microscale and
macroscale, while it reaches a maximum at the ranges that define the mesoscale
in this model. From a local perspective, the SCM is minimum both in highly
ordered and chaotic areas, while it reaches a maximum at the edges between such
areas. These characteristics suggest this is a good candidate for detecting the
mesoscale of arbitrary dynamical systems as well as regions where the
complexity is maximal in such systems.


title: Significance Relations for the Benchmarking of Meta-Heuristic Algorithms

abstract:
  The experimental analysis of meta-heuristic algorithm performance is usually
based on comparing average performance metric values over a set of algorithm
instances. When algorithms getting tight in performance gains, the additional
consideration of significance of a metric improvement comes into play. However,
from this moment the comparison changes from an absolute to a relative mode.
Here the implications of this paradigm shift are investigated. Significance
relations are formally established. Based on this, a trade-off between
increasing cycle-freeness of the relation and small maximum sets can be
identified, allowing for the selection of a proper significance level and
resulting ranking of a set of algorithms. The procedure is exemplified on the
CEC'05 benchmark of real parameter single objective optimization problems. The
significance relation here is based on awarding ranking points for relative
performance gains, similar to the Borda count voting method or the Wilcoxon
signed rank test. In the particular CEC'05 case, five ranks for algorithm
performance can be clearly identified.


title: Zero-Error Capacity of a Class of Timing Channels

abstract:
  We analyze the problem of zero-error communication through timing channels
that can be interpreted as discrete-time queues with bounded waiting times. The
channel model includes the following assumptions: 1) Time is slotted, 2) at
most $ N $ "particles" are sent in each time slot, 3) every particle is delayed
in the channel for a number of slots chosen randomly from the set $ \{0, 1,
\ldots, K\} $, and 4) the particles are identical. It is shown that the
zero-error capacity of this channel is $ \log r $, where $ r $ is the unique
positive real root of the polynomial $ x^{K+1} - x^{K} - N $.
Capacity-achieving codes are explicitly constructed, and a linear-time decoding
algorithm for these codes devised. In the particular case $ N = 1 $, $ K = 1 $,
the capacity is equal to $ \log \phi $, where $ \phi = (1 + \sqrt{5}) / 2 $ is
the golden ratio, and the constructed codes give another interpretation of the
Fibonacci sequence.


title:
The role of screened exact exchange in accurately describing properties
  of transition metal oxides: Modeling defects in LaAlO3

abstract:
  The properties of many intrinsic defects in the wide band gap semiconductor
LaAlO3 are studied using the screened hybrid functional of Heyd, Scuseria, and
Ernzerhof (HSE). As in pristine structures, exact exchange included in the
screened hybrid functional alleviates the band gap underestimation problem,
which is common to semilocal functionals; this allows accurate prediction of
defect properties. We propose correction-free defect energy levels for bulk
LaAlO3 computed using HSE that might serve as guide in the interpretation of
photoluminescence experiments.


title: Beyond information: A bit of meaning

abstract:
  Is our world just information? We argue that our current notion of
information has one serious shortcoming: It is quite literally meaningless. We
suggest a meaningful extension of the notion of information that is dynamic,
internal, approximate, contains an element of randomness, and is layered. This
new notion of information derives from the interactions of material objects.
Our answer to the essay question then is Bit from It or, more appropriately,
Bit++ from It. We discuss how our new notion of information sheds light on the
measurement problem in quantum mechanics and how it can be applied in
philosophy and computer science.


title:
Non-standard Skorokhod convergence of Levy-driven convolution integrals
  in Hilbert spaces

abstract:
  We study the convergence in probability in the non-standard $M_1$ Skorokhod
topology of the Hilbert valued stochastic convolution integrals of the type
$\int_0^t F_\gamma(t-s)\,d L(s)$ to a process $\int_0^t F(t-s)\, d L(s)$ driven
by a L\'evy process $L$. In Banach spaces we introduce strong, weak and product
modes of $M_1$-convergence, prove a criterion for the $M_1$-convergence in
probability of stochastically continuous c\`adl\`ag processes in terms of the
convergence in probability of the finite dimensional marginals and a good
behaviour of the corresponding oscillation functions, and establish criteria
for the convergence in probability of L\'evy driven stochastic convolutions.
The theory is applied to the infinitely dimensional integrated
Ornstein--Uhlenbeck processes with diagonalisable generators.


title: Verification for Reliable Product Lines

abstract:
  Many product lines are critical, and therefore reliability is a vital part of
their requirements. Reliability is a probabilistic property. We therefore
propose a model for feature-aware discrete-time Markov chains as a basis for
verifying probabilistic properties of product lines, including reliability. We
compare three verification techniques: The enumerative technique uses PRISM, a
state-of-the-art symbolic probabilistic model checker, on each product. The
parametric technique exploits our recent advances in parametric model checking.
Finally, we propose a new bounded technique that performs a single bounded
verification for the whole product line, and thus takes advantage of the common
behaviours of the product line. Experimental results confirm the advantages of
the last two techniques.


title: Inflationary power spectra with quantum holonomy corrections

abstract:
  In this paper we study slow-roll inflation with holonomy corrections from
loop quantum cosmology. Both tensor and scalar power spectra of primordial
perturbations are computed up to the first order in slow-roll parameters and
$V/\rho_{c}$, where $V$ is a potential of the scalar field and $\rho_{c}$ is a
critical energy density (expected to be of the order of the Planck energy
density). Possible normalizations of modes at short scales are discussed. In
case the normalization is performed with use of the Wronskian condition applied
to adiabatic vacuum, the tensor and scalar spectral indices are not quantum
corrected in the leading order. However, by choosing an alternative method of
normalization one can obtain quantum corrections in the leading order.
Furthermore, we show that the holonomy-corrected equation of motion for tensor
modes can be derived from an effective background metric. This allows us to
prove that the Wronskian normalization condition for the tensor modes preserves
the classical form.


title: Self-sustained activity, bursts, and variability in recurrent networks

abstract:
  There is consensus in the current literature that stable states of
asynchronous irregular spiking activity require (i) large networks of 10 000 or
more neurons and (ii) external background activity or pacemaker neurons. Yet
already in 1963, Griffith showed that networks of simple threshold elements can
be persistently active at intermediate rates. Here, we extend Griffith's work
and demonstrate that sparse networks of integrate-and-fire neurons assume
stable states of self-sustained asynchronous and irregular firing without
external input or pacemaker neurons. These states can be robustly induced by a
brief pulse to a small fraction of the neurons, or by short a period of
irregular input, and last for several minutes. Self-sustained activity states
emerge when a small fraction of the synapses is strong enough to significantly
influence the firing probability of a neuron, consistent with the recently
proposed long-tailed distribution of synaptic weights. During self-sustained
activity, each neuron exhibits highly irregular firing patterns, similar to
experimentally observed activity. Moreover, the interspike interval
distribution reveals that neurons switch between discrete states of high and
low firing rates. We find that self-sustained activity states can exist even in
small networks of only a thousand neurons. We investigated networks up to 100
000 neurons. Finally, we discuss the implications of self-sustained activity
for learning, memory and signal propagation.