title: Network and Plage Indices from Kodaikanal Ca-K Data

abstract:
  The Ca II K filtergrams from Kodaikanal Solar Observatory have been used to
study the solar activity. The images are dominated by the chromospheric network
and plages. Programs have been developed to obtain the network and plage
indices from the daily images as functions of solar latitude and time.
Preliminary results from the analysis are reported here. The network and plage
indices were found to follow the sunspot cycle. A secondary peak is found
during the declining activity period in both the indices. A comparison of
network indices from the northern and the southern hemispheres shows that the
former is more active than latter. However such an asymmetry is not clearly
seen in the case of plage index.


title: Soft vortex matter in a type-I/type-II superconducting bilayer

abstract:
  Magnetic flux patterns are known to strongly differ in the intermediate state
of type-I and type-II superconductors. Using a type-I/type-II bilayer we
demonstrate hybridization of these flux phases into a plethora of unique new
ones. Owing to a complicated multi-body interaction between individual
fluxoids, many different intriguing patterns are possible under applied
magnetic field, such as few-vortex clusters, vortex chains, mazes or
labyrinthal structures resembling the phenomena readily encountered in soft
matter physics. However, in our system the patterns are tunable by sample
parameters, magnetic field, current and temperature, which reveals transitions
from short-range clustering to long-range ordered phases such as parallel
chains, gels, glasses and crystalline vortex lattices, or phases where lamellar
type-I flux domains in one layer serve as a bedding potential for type-II
vortices in the other - configurations clearly beyond the soft-matter analogy.


title:
Neutral and Ionized Hydrides in Star-forming Regions -- Observations
  with Herschel/HIFI

abstract:
  The cosmic abundance of hydrides depends critically on high-energy UV, X-ray,
and particle irradiation. Here we study hydrides in star-forming regions where
irradiation by the young stellar object can be substantial, and density and
temperature can be much enhanced over interstellar values. Lines of OH, CH, NH,
SH and their ions OH+, CH+, NH+, SH+, H2O+, and H3O+ were observed in
star-forming regions by the HIFI spectrometer onboard the Herschel Space
Observatory. Molecular column densities are derived from observed ground-state
lines, models, or rotational diagrams. We report here on two prototypical
high-mass regions, AFGL 2591 and W3 IRS5, and compare them to chemical
calculations making assumptions on the high-energy irradiation. A model
assuming no ionizing protostellar emission is compared with (i) a model
assuming strong protostellar X-ray emission and (ii) a two-dimensional (2D)
model including emission in the far UV (FUV, 6 -- 13.6 eV) irradiating the
outflow walls that separate the outflowing gas and infalling envelope material.
We confirm that the effect of FUV in two dimensional models with enlarged
irradiated surfaces is clearly noticeable. A molecule that is very sensitive to
FUV irradiation is CH+, enhanced in abundance by more than 5 orders of
magnitude. The HIFI observations of CH+ lines agree with the two-dimensional
FUV model by Bruderer et al. which computes abundances, non-LTE excitation and
line radiative transfer.{Ref 20} It is concluded that CH+ is a good FUV tracer
in star-forming regions. The effect of potential X-ray irradiation is not
excluded, but cannot be demonstrated by the present data.


title:
On entire functions restricted to intervals, partition of unities, and
  dual Gabor frames

abstract:
  Partition of unities appear in many places in analysis. Typically they are
generated by compactly supported functions with a certain regularity. In this
paper we consider partition of unities obtained as integer-translates of entire
functions restricted to finite intervals. We characterize the entire functions
that lead to a partition of unity in this way, and we provide characterizations
of the "cut-off" entire functions, considered as functions of a real variable,
to have desired regularity. In particular we obtain partition of unities
generated by functions with small support and desired regularity. Applied to
Gabor analysis this leads to constructions of dual pairs of Gabor frames with
low redundancy, generated by trigonometric polynomials with small support and
desired regularity.


title: The radius discrepancy in low mass stars: single vs. binaries

abstract:
  A long-standing issue in the theory of low mass stars is the discrepancy
between predicted and observed radii and effective temperatures. In spite of
the increasing availability of very precise radius determinations from
eclipsing binaries and interferometric measurements of radii of single stars,
there is no unanimous consensus on the extent (or even the existence) of the
discrepancy and on its connection with other stellar properties (e.g.
metallicity, magnetic activity). We investigate the radius discrepancy
phenomenon using the best data currently available (accuracy about 5%). We have
constructed a grid of stellar models covering the entire range of low mass
stars (0.1-1.25 M_sun) and various choices of the metallicity and of the mixing
length parameter \alpha. We used an improved version of the Yale Rotational
stellar Evolution Code (YREC), implementing surface boundary conditions based
on the most up-to-date PHOENIX atmosphere models. Our models are in good
agreement with others in the literature and improve and extend the low mass end
of the Yale-Yonsei isochrones. Our calculations include rotation-related
quantities, such as moments of inertia and convective turnover time scales,
useful in studies of magnetic activity and rotational evolution of solar-like
stars. Consistently with previous works, we find that both binaries and single
stars have radii inflated by about 3% with respect to the theoretical models;
among binaries, the components of short orbital period systems are found to be
the most deviant. We conclude that both binaries and single stars are
comparably affected by the radius discrepancy phenomenon.


title: The global extension problem, co-flag and metabelian Leibniz algebras

abstract:
  Let $\mathfrak{L}$ be a Leibniz algebra, $E$ a vector space and $\pi : E \to
\mathfrak{L}$ an epimorphism of vector spaces with $ \mathfrak{g} = {\rm Ker}
(\pi)$. The global extension problem asks for the classification of all Leibniz
algebra structures that can be defined on $E$ such that $\pi : E \to
\mathfrak{L}$ is a morphism of Leibniz algebras: from a geometrical viewpoint
this means to give the decomposition of the groupoid of all such structures in
its connected components and to indicate a point in each component. All such
Leibniz algebra structures on $E$ are classified by a global cohomological
object ${\mathbb G} {\mathbb H} {\mathbb L}^{2} \, (\mathfrak{L}, \,
\mathfrak{g})$ which is explicitly constructed. It is shown that ${\mathbb G}
{\mathbb H} {\mathbb L}^{2} \, (\mathfrak{L}, \, \mathfrak{g})$ is the
coproduct of all local cohomological objects $ {\mathbb H} {\mathbb L}^{2} \,
\, (\mathfrak{L}, \, (\mathfrak{g}, [-,-]_{\mathfrak{g}}))$ that are
classifying sets for all extensions of $\mathfrak{L}$ by all Leibniz algebra
structures $(\mathfrak{g}, [-,-]_{\mathfrak{g}})$ on $\mathfrak{g}$. The second
cohomology group ${\rm HL}^2 \, (\mathfrak{L}, \, \mathfrak{g})$ of Loday and
Pirashvili appears as the most elementary piece among all components of
${\mathbb G} {\mathbb H} {\mathbb L}^{2} \, (\mathfrak{L}, \, \mathfrak{g})$.
Several examples are worked out in details for co-flag Leibniz algebras over
$\mathfrak{L}$, i.e. Leibniz algebras $\mathfrak{h}$ that have a finite chain
of epimorphisms of Leibniz algebras $\mathfrak{L}_n : = \mathfrak{h}
\stackrel{\pi_{n}}{\longrightarrow} \mathfrak{L}_{n-1} \, \cdots \,
\mathfrak{L}_1 \stackrel{\pi_{1}} {\longrightarrow} \mathfrak{L}_{0} :=
\mathfrak{L}$ such that ${\rm dim} ({\rm Ker} (\pi_{i})) = 1$, for all $i = 1,
\cdots, n$.


title: Determinantal Representations and B\'ezoutians

abstract:
  We show that for every smooth hyperbolic polynomial h there is another
hyperbolic polynomial q such that qh has a definite determinantal
representation. This is proved by considering sum-of-squares decompositions of
certain bilinear forms called B\'ezoutians. Besides commutative algebra, the
proof relies on results from real algebraic geometry.


title:
A Functional Limit Theorem for stochastic integrals driven by a
  time-changed symmetric \alpha-stable L\'evy process

abstract:
  Under proper scaling and distributional assumptions, we prove the convergence
in the Skorokhod space endowed with the M_1-topology of a sequence of
stochastic integrals of a deterministic function driven by a time-changed
symmetric \alpha-stable L\'evy process. The time change is given by the inverse
\beta-stable subordinator.


title: Rydberg-dressing of atoms in optical lattices

abstract:
  We study atoms in optical lattices whose electronic ground state is
off-resonantly coupled to a highly excited state with strong binary
interactions. We present a time-dependent treatment of the resulting quantum
dynamics, which -- contrary to recent predictions [Phys. Rev. Lett. 110, 213005
(2013)] -- proves that the strong repulsion between the weakly admixed Rydberg
states does not lead to atomic trap-loss. This finding provides an important
basis for creating and manipulating coherent long-range interactions in optical
lattice experiments.


title:
X-Shooter spectroscopy of young stellar objects III. Photospheric and
  chromospheric properties of Class III objects

abstract:
  We analyzed X-Shooter/VLT spectra of 24 ClassIII sources from three nearby
star-forming regions (sigmaOrionis, LupusIII, and TWHya). We determined the
effective temperature, surface gravity, rotational velocity, and radial
velocity by comparing the observed spectra with synthetic BT-Settl model
spectra. We investigated in detail the emission lines emerging from the stellar
chromospheres and combined these data with archival X-ray data to allow for a
comparison between chromospheric and coronal emissions. Both X-ray and Halpha
luminosity as measured in terms of the bolometric luminosity are independent of
the effective temperature for early-M stars but decline toward the end of the
spectral M sequence. For the saturated early-M stars the average emission level
is almost one dex higher for X-rays than for Halpha: log(L_x/L_bol) = -2.85 +-
0.36 vs. log(L_Halpha/L_bol) = -3.72 +- 0.21. When all chromospheric emission
lines (including the Balmer series up to H11, CaII HK, the CaII infrared
triplet, and several HeI lines) are summed up the coronal flux still dominates
that of the chromosphere, typically by a factor 2-5. Flux-flux relations
between activity diagnostics that probe different atmospheric layers (from the
lower chromosphere to the corona) separate our sample of active pre-main
sequence stars from the bulk of field M dwarfs studied in the literature. Flux
ratios between individual optical emission lines show a smooth dependence on
the effective temperature. The Balmer decrements can roughly be reproduced by
an NLTE radiative transfer model devised for another young star of similar age.
Future, more complete chromospheric model grids can be tested against this data
set.


title:
Angular Reconstruction of a Lead Scintillating-Fiber Sandwiched
  Electromagnetic Calorimeter

abstract:
  A new method called Neighbor Cell Deposited Energy Ratio (NCDER) is proposed
to reconstruct incidence position in a single layer for a 3-dimensional imaging
electromagnetic calorimeter (ECAL).This method was applied to reconstruct the
ECAL test beam data for the Alpha Magnetic Spectrometer-02 (AMS-02). The
results show that this method can achieve an angular resolution of 7.36\pm 0.08
/ \sqrt(E) \oplus 0.28 \pm 0.02 degree in the determination of the photons
direction, which is much more precise than that obtained with the
commonly-adopted Center of Gravity(COG) method (8.4 \pm 0.1 /sqrt(E) \oplus
0.8\pm0.3 degree). Furthermore, since it uses only the properties of
electromagnetic showers, this new method could also be used for other type of
fine grain sampling calorimeters.


title:
Akhmediev breathers, Ma solitons and general breathers from rogue waves:
  A case study in Manakov system

abstract:
  We present explicit forms of general breather (GB), Akhmediev breather (AB),
Ma soliton (MS) and rogue wave (RW) solutions of the two component nonlinear
Schr\"{o}dinger (NLS) equation, namely Manakov equation. We derive these
solutions through two different routes. In the forward route we first construct
a suitable periodic envelope soliton solution to this model from which we
derive GB, AB, MS and RW solutions. We then consider the RW solution as the
starting point and derive AB, MS and GB in the reverse direction. The second
approach has not been illustrated so far for the two component NLS equation.
Our results show that the above rational solutions of the Manakov system can be
derived from the standard scalar nonlinear Schr\"{o}dinger equation with a
modified nonlinearity parameter. Through this two way approach we establish a
broader understanding of these rational solutions which will be of interest in
a variety of situations.


title:
Continuous dependence on the coefficients for a class of non-autonomous
  evolutionary equations

abstract:
  The continuous dependence of solutions to certain (non-autonomous, partial,
integro-differential-algebraic, evolutionary) equations on the coefficients is
addressed. We give criteria that guarantee that convergence of the coefficients
in the weak operator topology implies weak convergence of the respective
solutions. We treat three examples: A homogenization problem for a Kelvin-Voigt
model for elasticity, the discussion of continuous dependence of the
coefficients for acoustic waves with impedance type boundary conditions and a
singular perturbation problem for a mixed type equation. By means of counter
examples we show optimality of the results obtained.


title:
Isospin dependence of entrainment in superfluid neutron stars in a
  relativistic model

abstract:
  We study the entrainment effect between superfluid neutrons and charge
neutral fluid (called the proton fluid) which is made of protons and electrons
in neutron star interior within the two fluid formalism and using a
relativistic model where baryon-baryon interaction is mediated by the exchange
of $\sigma$, $\omega$ and $\rho$ mesons. This model of strong interaction also
includes scalar self interactions. The entrainment matrix and entrainment
parameter are calculated using the parameter sets of Glendenning (GL) and
another non-linear (NL3) interaction. The inclusion of $\rho$ mesons strongly
influences the entrainment parameter ($\epsilon_{mom}$) in a superfluid neutron
star. The entrainment parameter is constant at the core and drops rapidly at
the surface. It takes values within the physical range.


title: Beta-decay of Mn-65 to Fe-65

abstract:
  The low energy structure of Fe-65 has been studied by means of gamma- and
fast-timing spectroscopy. A level scheme of Fe-65 populated following the
beta-decay of Mn-65 was established for the first time. It includes 41 levels
and 85 transitions. The excitation energy of the beta-decaying isomer in Fe-65
has been precisely determined at 393.7(2) keV. The beta delayed neutron
emission branch was measured as Pn = 7.9(12)%, which cannot be reconciled with
the previously reported value of 21.0(5)%. Four gamma-rays and four excited
states in Fe-64 were identified as being populated following the beta-n decay.
Four lifetimes and five lifetime limits in the subnanosecond range have been
measured using the Advanced Time-Delayed Method. The level scheme is compared
with shell-model calculations. Tentative spin and parity assignments are
proposed based on the observed transition rates, the calculations and the
systematics of the region.


title: Baby de Sitter Black Holes and dS$_3$/CFT$_2$

abstract:
  Unlike three-dimensional Einstein gravity, three-dimensional massive gravity
admits asymptotically de Sitter space (dS) black hole solutions. These black
holes present interesting features and provide us with toy models to study the
dS/CFT correspondence. A remarkable property of these black holes is that they
are always in thermal equilibrium with the cosmological horizon of the space
that hosts them. This invites us to study the thermodynamics of these solutions
within the context of dS/CFT. We study the asymptotic symmetry group of the
theory and find that it indeed coincides with the local two-dimensional
conformal algebra. The charge algebra associated to the asymptotic Killing
vectors consists of two copies of the Virasoro algebra with non-vanishing
central extension. We compute the mass and angular momentum of the dS black
holes and verify that a naive application of Cardy's formula exactly reproduces
the entropy of both the black hole and the cosmological horizon. By adapting
the holographic renormalization techniques to the case of dS space, we define
the boundary stress tensor of the dual Euclidean conformal field theory.


title: Limits on Lorentz violation from forbidden beta decays

abstract:
  Forbidden (slow) beta decays offer new opportunities to test the invariance
of the weak interaction under Lorentz transformations. Within a general
effective field theory framework we analyze and reinterpret the only two
relevant experiments, performed in the 1970s, dedicated to search for a
preferred direction in space in first- and second-forbidden beta decays. We
show that the results of these experiments put strong and unique limits on
Lorentz violation, and in particular on the presence of several interactions in
the modern Lorentz-violating Standard Model extension. We discuss prospects to
improve on these limits.


title: Cooperative Network Coded ARQ Strategies for Two Way Relay Channel

abstract:
  In this paper, novel cooperative automatic repeat request (ARQ) methods with
network coding are proposed for two way relaying network. Upon a failed
transmission of a packet, the network enters cooperation phase, where the
retransmission of the packets is aided by the relay node. The proposed approach
integrates network coding into cooperative ARQ, aiming to improve the network
throughput by reducing the number of retransmissions. For successive
retransmission, three different methods for choosing the retransmitting node
are considered. The throughput of the methods are analyzed and compared. The
analysis is based on binary Markov channel which takes the correlation of the
channel coefficients in time into account. Analytical results show that the
proposed use of network coding result in throughput performance superior to
traditional ARQ and cooperative ARQ without network coding. It is also observed
that correlation can have significant effect on the performance of the proposed
cooperative network coded ARQ approach. In particular the proposed approach is
advantageous for slow to moderately fast fading channels.


title:
Insight into the Properties of the UK Power Consumption Using a Linear
  Regression and Wavelet Transform Approach

abstract:
  In this paper, the relationship between the Gross Domestic Product (GDP), air
temperature variations and power consumption is evaluated using the linear
regression and Wavelet Coherence (WTC) approach on a 1971-2011 time series for
the United Kingdom (UK). The results based on the linear regression approach
indicate that some 66% variability of the UK electricity demand can be
explained by the quarterly GDP variations, while only 11% of the quarterly
changes of the UK electricity demand are caused by seasonal air temperature
variations. WTC however, can detect the period of time when GDP and air
temperature significantly correlate with electricity demand and the results of
the wavelet correlation at different time scales indicate that a significant
correlation is to be found on a long-term basis for GDP and on an annual basis
for seasonal air-temperature variations. This approach provides an insight into
the properties of the impact of the main factors on power consumption on the
basis of which the power system development or operation planning and
forecasting the power consumption can be improved.


title:
Comment on "Inflation with a graceful exit and entrance driven by
  Hawking radiation"

abstract:
  Modak and Singleton [Phys. Rev. D 86, 123515 (2012)] have presented
Hawking-like radiation for cosmological inflation which has a natural "turn on"
and a natural "turn off" mechanism. This Hawking-like radiation results in an
effective negative pressure "fluid" which leads to a rapid period of expansion
in the very early Universe. We discuss that the turn on mechanism can not
happen for FRW model in early universe because its horizon is apparent horizon
not event horizon. Hence, we cannot apply geometric optic approximation which
is a necessary condition for tunneling method. It was shown that this model
predict a value for $\frac{\rho}{m_{pl}^4}$ which is bigger than the COBE
normalization constraint in the Cosmic Microwave Background (CMB) at the
horizon exit.


title: Stacking Textures and Singularities in Bilayer Graphene

abstract:
  We study a family of globally smooth spatially varying two dimensional
stacking textures in bilayer graphene. We find that the strain-minimizing
stacking patterns connecting inequivalent ground states with local $AB$ and
$BA$ interlayer registries are two dimensional twisted textures of an
interlayer displacement field. We construct and display these topological
stacking textures for bilayer graphene, examine their interactions and develop
the composition rules that allow us to represent other more complex stacking
textures, including globally twisted graphenes and extended one dimensional
domain walls.


title: Wider Thin-Very Tall Superatomic Boolean Algebras

abstract:
  For each regular cardinal k > w we show the consistent existence of a thin
very tall superatomic Boolean algebra of width k.


title:
A Comparison of Algorithms for Learning Hidden Variables in Normal
  Graphs

abstract:
  A Bayesian factor graph reduced to normal form consists in the
interconnection of diverter units (or equal constraint units) and
Single-Input/Single-Output (SISO) blocks. In this framework localized
adaptation rules are explicitly derived from a constrained maximum likelihood
(ML) formulation and from a minimum KL-divergence criterion using KKT
conditions. The learning algorithms are compared with two other updating
equations based on a Viterbi-like and on a variational approximation
respectively. The performance of the various algorithm is verified on synthetic
data sets for various architectures. The objective of this paper is to provide
the programmer with explicit algorithms for rapid deployment of Bayesian graphs
in the applications.


title: Gelfand type problem for two phase porous media

abstract:
  We consider a generalization of the Gelfand problem arising in
Frank-Kamenetskii theory of thermal explosion. This generalization is a natural
extension of the Gelfand problem to two phase materials, where, in contrast to
the classical Gelfand problem which utilizes single temperature approach, the
state of the system is described by two different temperatures. We show that
similar to the classical Gelfand problem the thermal explosion occurs
exclusively due to the absence of stationary temperature distribution. We also
show that the presence of inter-phase heat exchange delays a thermal explosion.
Moreover, we prove that in the limit of infinite heat exchange between phases
the problem of thermal explosion in two phase porous media reduces to the
classical Gelfand problem with renormalized constants.


title:
Minimizing configurations and Hamilton-Jacobi equations of homogeneous
  N-body problems

abstract:
  For $N$-body problems with homogeneous potentials we define a special class
of central configurations related with the reduction of homotheties in the
study of homogeneous weak KAM solutions. For potentials in $1/r^\alpha$ with
$\alpha\in (0,2)$ we prove the existence of homogeneous weak KAM solutions. We
show that such solutions are related to viscosity solutions of another
Hamilton-Jacobi equation in the sphere of normal configurations. As an
application we prove for the Newtonian three body problem that there are no
smooth homogeneous solutions to the critical Hamilton-Jacobi equation.


title: The Higgs Particle and Higher-Dimensional Theories

abstract:
  In spite of the great success of LHC experiments, we do not know whether the
discovered "standard model-like" Higgs particle is really what the standard
model predicts or a particle some new physics has in its low energy effective
theory. Also the long-standing problems concerning the property of Higgs and
its interactions are still there, and we still do not have any conclusive
argument of the origin of the Higgs itself.
  In this article we focus on higher-dimensional theories as new physics. First
we give a brief review of their representative scenarios and closely related
4-dimensional scenarios. Among them, we mainly discuss two interesting
possibilities of the origin of the Higgs: Higgs as a gauge boson and Higgs as a
(pseudo) Nambu-Goldstone boson.
  Next, we argue that theories of new physics are divided into two categories,
i.e. theories with normal Higgs interactions and those with anomalous Higgs
interactions. Interestingly both of two candidates concerning the origin of the
Higgs mentioned above predict characteristic "anomalous" Higgs interactions,
such as the deviation of the Yukawa couplings from the standard model
predictions. Such deviations can be hopefully investigated by the precision
tests of Higgs interactions at the planned ILC experiment.
  Also discussed is the main decay mode of the Higgs, $H \to \gamma \gamma$.
Again, theories belonging different categories are known to predict remarkably
different new physics contributions to this important process.


title:
Higher-order Cauchy of the second kind and poly-Cauchy of the second
  kind mixed type polynomials

abstract:
  In this paper, we investigate some properties of higher-order Cauchy of the
second kind and poly-Cauchy of the second mixed type polynomials with umbral
calculus viewpoint. From our investigation, we derive many interesting
identities of higher-order Cauchy of the second kind and poly-Cauchy of the
second kind mixed type polynomials.


title:
Relevance of Two Boson Exchange Effect in Quasi-Elastic Charged Current
  Neutrino-Nucleon Interaction

abstract:
  Two boson exchange (TBE) correction to the cross section for the
quasi-elastic charged current $\nu n$ and $\bar{\nu} p$ scattering is
evaluated. The TBE is given by $W\gamma$ box diagrams. The calculations are
performed for 1 GeV neutrinos. The averaged TBE correction is of the order of
$2\div4 %$ (with respect to Born contribution) in the case of $\nu_e$ and
$\bar{\nu}_e$ and $1\div2 %$ in the case of $\nu_\mu$ and $\bar{\nu}_\mu$. The
impact of the TBE effect on the systematic discrepancy between the $\nu_e$ and
$\nu_\mu$ cross sections is discussed.


title:
Ultra-stable cryogenic optical resonators for tests of fundamental
  physics

abstract:
  We present the design and first measurement results for an ultra-stable
cryogenically cooled optical sapphire resonator system with a potential
relative frequency stability better than 3x10^-17. This level of oscillator
stability allows for more precise tests of Einstein's theories of relativity
and thus could help to find first hints of "new physics". We will give some
details on a projected experiment to test Lorentz invariance that will utilize
these cavities.


title: Mass dependence of nuclear short- range correlations and the EMC effect

abstract:
  We sketch an approximate method to quantify the number of correlated pairs in
any nucleus $A$. It is based on counting independent-particle model (IPM)
nucleon-nucleon pairs in a relative $S$-state with no radial excitation. We
show that IPM pairs with those quantum numbers are most prone to short-range
correlations and are at the origin of the high-momentum tail of the nuclear
momentum distributions. Our method allows to compute the $a_2$ ratios extracted
from inclusive electron scattering. Furthermore, our results reproduce the
observed linear correlation between the number of correlated pairs and the
magnitude of the EMC effect. We show that the width of the pair center-of-mass
distribution in exclusive two-nucleon knockout yields information on the
quantum numbers of the pairs.


title: Asymptotic geometry in higher products of rank one Hadamard spaces

abstract:
  Given a product X of locally compact rank one Hadamard spaces, we study
asymptotic properties of certain discrete isometry groups. First we give a
detailed description of the structure of the geometric limit set and relate it
to the limit cone; moreover, we show that the action of the group on a quotient
of the regular geometric boundary of X is minimal and proximal. This is
completely analogous to the case of Zariski dense discrete subgroups of
semi-simple Lie groups acting on the associated symmetric space. In the second
part of the paper we study the distribution of orbit points in X: As a
generalization of the critical exponent we consider the exponential growth rate
of the number of orbit points in X with a prescribed "slope". We show in
particular that this exponential growth rate is strictly positive in the
relative interior of the limit cone and that there exists a unique slope for
which it is maximal and equal to the critical exponent.
  We notice that an interesting class of product spaces as above comes from the
second alternative in the Rank Rigidity Theorem for CAT(0)-cube complexes:
Given a finite-dimensional CAT(0)-cube complex X and a group G of automorphisms
without fixed point in the geometric compactification of X, then either G
contains a rank one isometry or there exists a convex F-invariant subcomplex of
X which is a product of two unbounded cube subcomplexes; in the latter case one
inductively gets a convex G-invariant subcomplex of X which can be decomposed
into a finite product of rank one Hadamard spaces. So our results imply in
particular that classical properties of discrete subgroups of higher rank Lie
groups (as stated e.g. by Y. Benoist and J.F. Quint) also hold for certain
discrete isometry groups of reducible CAT(0)-cube complexes.


title:
Rewriting XPath Queries using View Intersections: Tractability versus
  Completeness

abstract:
  The standard approach for optimization of XPath queries by rewriting using
views techniques consists in navigating inside a view's output, thus allowing
the usage of only one view in the rewritten query. Algorithms for richer
classes of XPath rewritings, using intersection or joins on node identifiers,
have been proposed, but they either lack completeness guarantees, or require
additional information about the data. We identify the tightest restrictions
under which an XPath can be rewritten in polynomial time using an intersection
of views and propose an algorithm that works for any documents or type of
identifiers. As a side-effect, we analyze the complexity of the related problem
of deciding if an XPath with intersection can be equivalently rewritten as one
without intersection or union. We extend our formal study of the view-based
rewriting problem for XPath by describing also (i) algorithms for more complex
rewrite plans, with no limitations on the number of intersection and navigation
steps inside view outputs they employ, and (ii) adaptations of our techniques
to deal with XML documents without persistent node Ids, in the presence of XML
keys. Complementing our computational complexity study, we describe a
proof-of-concept implementation of our techniques and possible choices that may
speed up execution in practice, regarding how rewrite plans are built, tested
and executed. We also give a thorough experimental evaluation of these
techniques, focusing on scalability and the running time improvements achieved
by the execution of view-based plans.


title:
SLP compression for solutions of equations with constraints in free and
  hyperbolic groups

abstract:
  The paper is a part of an ongoing program which aims to show that the
existential theory in free groups (hyperbolic groups or even toral relatively
hyperbolic) is NP-complete. For that we study compression of solutions with
straight-line programs (SLPs) as suggested originally by Plandowski and Rytter
in the context of a single word equation. We review some basic results on SLPs
and give full proofs in order to keep this fundamental part of the program
self-contained. Next we study systems of equations with constraints in free
groups and more generally in free products of abelian groups. We show how to
compress minimal solutions with extended Parikh-constraints. This type of
constraints allows to express semi linear conditions as e.g. alphabetic
information. The result relies on some combinatorial analysis and has not been
shown elsewhere. We show similar compression results for Boolean formula of
equations over a torsion-free $\delta$-hyperbolic group. The situation is much
more delicate than in free groups. As byproduct we improve the estimation of
the "capacity" constant used by Rips and Sela in their paper "Canonical
representatives and equations in hyperbolic groups" from a double-exponential
bound in $\delta$ to some single-exponential bound. The final section shows
compression results for toral relatively hyperbolic group using the work of
Dahmani: We show that given a system of equations over a fixed toral relatively
hyperbolic group, for every solution of length $N$ there is an SLP for another
solution such that the size of the SLP is bounded by some polynomial $p(s+ \log
N)$ where $s$ is the size of the system.


title:
HOOMD-blue: A Python package for high-performance molecular dynamics and
  hard particle Monte Carlo simulations

abstract:
  HOOMD-blue is a particle simulation engine designed for nano- and
colloidal-scale molecular dynamics and hard particle Monte Carlo simulations.
It has been actively developed since March 2007 and available open source since
August 2008. HOOMD-blue is a Python package with a high performance C++/CUDA
backend that we built from the ground up for GPU acceleration. The Python
interface allows users to combine HOOMD-blue with with other packages in the
Python ecosystem to create simulation and analysis workflows. We employ
software engineering practices to develop, test, maintain, and expand the code.


title: Special values of the hypergeometric series

abstract:
  In this paper, we present a new method for finding identities for
hypergeoemtric series, such as the (Gauss) hypergeometric series, the
generalized hypergeometric series and the Appell-Lauricella hypergeometric
series. Furthermore, using this method, we get identities for the
hypergeometric series $F(a,b;c;x)$; we show that values of $F(a,b;c;x)$ at some
points $x$ can be expressed in terms of gamma functions, together with certain
elementary functions. We tabulate the values of $F(a,b;c;x)$ that can be
obtained with this method. We find that this set includes almost all previously
known values and many previously unknown values.
  Key Words and Phrases: hypergeometric series, three term relation, special
value, solving polynomial systems.


title:
Phonon Bose-Einstein condensation in a Hubbard-phonon interacting system
  with infrared divergence

abstract:
  We show that a finite Hubbard-phonon interacting system exhibits phonon BEC
at sufficiently low temperature. We also have the gauge symmetry breaking for
phonons. The key tools are a unitary transformation introduced by Arai and
Hirokawa \protect{\cite{AH1}} and the Araki-Woods representation. This system
is essentially the same as a free system or the van Hove model.


title: Optics of a Gas of Coherently Spinning Molecules

abstract:
  We consider optical properties of a gas of molecules that are brought to fast
unidirectional spinning by a pulsed laser field. It is shown that a circularly
polarized probe light passing through the medium inverts its polarization
handedness and experiences a frequency shift controllable by the sense and the
rate of molecular rotation. Our analysis is supported by two recent experiments
on the laser-induced rotational Doppler effect in molecular gases, and provides
a good qualitative and quantitative description of the experimental
observations.


title:
Tuning of one-dimensional plasmons by Ag-Doping in Ag-$\sqrt{3}$-ordered
  atomic wires

abstract:
  We generated arrays of silver wires with a height of one atom and an average
width of 11 atoms on the Si(557) surface via self assembly with local
$\sqrt{3}\times\sqrt{3}$ order, and investigated the 1D plasmon formation in
them using a combination of high resolution electron loss spectroscopy with low
energy electron diffraction. As it turned out by a series of thermal desorption
experiments followed by adding small concentrations of Ag, pure Ag-$\sqrt{3}$
ordered arrays of nanowires, separated by (113) facets, are intrinsically
semi-metallic or semiconducting. Added Ag atoms in the range up to few percent
of a monolayer result in 1D plasmon formation without any concentration
threshold. The quantitative Ag concentration dependence of the plasmonic losses
is clearly non-linear and fully compatible with a $\sqrt{n_e}$ dependence of
the 1D plasmon. Adsorption of traces of residual gas can have a qualitatively
similar doping effect.


title: Wave relations

abstract:
  The wave equation (free boson) problem is studied from the viewpoint of the
relations on the symplectic manifolds associated to the boundary induced by
solutions. Unexpectedly there is still something to say on this simple,
well-studied problem. In particular, boundaries which do not allow for a
meaningful Hamiltonian evolution are not problematic from the viewpoint of
relations. In the two-dimensional Minkowski case, these relations are shown to
be Lagrangian. This result is then extended to a wide class of metrics and is
conjectured to be true also in higher dimensions for nice enough metrics. A
counterexample where the relation is not Lagrangian is provided by the Misner
space.

categories: math-ph math.AP math.AT math.DG math.MP math.SG


title:
Bright Debris Disk Candidates Observed with AKARI/Far-Infrared Surveyor
  (FIS)

abstract:
  We cross-correlate \hip\ main-sequence star catalog with \fis\ catalog, and
identify 136 stars (at $>90$% reliability) with far-infrared detections at
least in one band. After rejecting 51 stars classified as young stellar
objects, Be stars, other type stars with known dust disks or with potential
contaminations and 2 stars without infrared excess emission, we obtain a sample
of 83 candidate stars with debris disks. Stars in our sample cover spectral
types from B to K-types with most being early types. This represents an unique
sample of luminous debris disks that derived uniformly from all sky survey with
a spatial resolution a factor of two better than the previous such survey by
\iras. Moreover, by collecting the infrared photometric data from other public
archives, 85% of them have infrared excesses in more than one bands, allowing
the estimate of the dust temperatures. We fit the blackbody model to the broad
band spectral energy distribution of these stars to derive the statistical
distribution of the disk parameters. 7 stars require an additional warm
component of temperature around 200 K. While a substantial fraction of our
sample(58 stars) have weak 12 \micron\ excess indicating that a warm dust
component maybe common among these bright debris disk systems.


title:
739 observed NEAs and new 2-4m survey statistics within the EURONEAR
  network

abstract:
  We report follow-up observations of 477 program Near-Earth Asteroids (NEAs)
using nine telescopes of the EURONEAR network having apertures between 0.3 and
4.2 m. Adding these NEAs to our previous results we now count 739 program NEAs
followed-up by the EURONEAR network since 2006. The targets were selected using
EURONEAR planning tools focusing on high priority objects. Analyzing the
resulting orbital improvements suggests astrometric follow-up is most important
days to weeks after discovery, with recovery at a new opposition also valuable.
Additionally we observed 40 survey fields spanning three nights covering 11 sq.
degrees near opposition, using the Wide Field Camera on the 2.5m Isaac Newton
Telescope (INT), resulting in 104 discovered main belt asteroids (MBAs) and
another 626 unknown one-night objects. These fields, plus program NEA fields
from the INT and from the wide field MOSAIC II camera on the Blanco 4m
telescope, generated around 12,000 observations of 2,000 minor planets (mostly
MBAs) observed in 34 square degrees. We identify Near Earth Object (NEO)
candidates among the unknown (single night) objects using three selection
criteria. Testing these criteria on the (known) program NEAs shows the best
selection methods are our epsilon-miu model which checks solar elongation and
sky motion and the MPC's NEO rating tool. Our new data show that on average 0.5
NEO candidates per square degree should be observable in a 2m-class survey (in
agreement with past results), while an average of 2.7 NEO candidates per square
degree should be observable in a 4m-class survey (although our Blanco
statistics were affected by clouds). At opposition just over 100 MBAs (1.6
unknown to every 1 known) per square degree are detectable to R=22 in a 2m
survey based on the INT data, while our two best ecliptic Blanco fields away
from opposition lead to 135 MBAs (2 unknown to every 1 known) to R=23.


title:
The central role of Bayes theorem for joint estimation of causal effects
  and propensity scores

abstract:
  Although propensity scores have been central to the estimation of causal
effects for over 30 years, only recently has the statistical literature begun
to consider in detail methods for Bayesian estimation of propensity scores and
causal effects. Underlying this recent body of literature on Bayesian
propensity score estimation is an implicit discordance between the goal of the
propensity score and the use of Bayes theorem. The propensity score condenses
multivariate covariate information into a scalar to allow estimation of causal
effects without specifying a model for how each covariate relates to the
outcome. Avoiding specification of a detailed model for the outcome response
surface is valuable for robust estimation of causal effects, but this strategy
is at odds with the use of Bayes theorem, which presupposes a full probability
model for the observed data. The goal of this paper is to explicate this
fundamental feature of Bayesian estimation of causal effects with propensity
scores in order to provide context for the existing literature and for future
work on this important topic.


title:
Thermodynamic phases and mesonic fluctuations in a chiral nucleon-meson
  model

abstract:
  Studies of the QCD phase diagram must properly include nucleonic degrees of
freedom and their thermodynamics in the range of baryon chemical potentials
characteristic of nuclear matter. A useful framework for incorporating relevant
nuclear physics constraints in this context is a chiral nucleon-meson effective
Lagrangian. In the present paper, such a chiral nucleon-meson model is extended
with systematic inclusion of mesonic fluctuations using the functional
renormalization group approach. The resulting description of the nuclear
liquid-gas phase transition shows a remarkable agreement with three-loop
calculations based on in-medium chiral effective field theory. No signs of a
chiral first-order phase transition and its critical endpoint are found in the
region of applicability of the model, at least up to twice the density of
normal nuclear matter and at temperatures T<100 MeV. Fluctuations close to the
critical point of the first-order liquid-gas transition are also examined with
a detailed study of the chiral susceptibility.


title: Sparse Channel Estimation by Factor Graphs

abstract:
  The problem of estimating a sparse channel, i.e. a channel with a few
non-zero taps, appears in various areas of communications. Recently, we have
developed an algorithm based on iterative alternating minimization which
iteratively detects the location and the value of the taps. This algorithms
involves an approximate Maximum A Posteriori (MAP) probability scheme for
detection of the location of taps, while a least square method is used for
estimating the values at each iteration. In this work, based on the method of
factor graphs and message passing algorithms, we will compute an exact solution
for the MAP estimation problem. Indeed, we first find a factor graph model of
this problem, and then perform the well-known min-sum algorithm on the edges of
this graph. Consequently, we will find an exact estimator for the MAP problem
that its complexity grows linearly with respect to the channel memory. By
substituting this estimator in the mentioned alternating minimization method,
we will propose an estimator that will nearly achieve the Cramer-Rao bound of
the genie-aided estimation of sparse channels (estimation based on knowing the
location of non-zero taps of the channel), while it can perform faster than
most of the proposed algorithms in literature.


title: Future applications of the Yang-Mills gradient flow in lattice QCD

abstract:
  The Yang--Mills gradient flow has many interesting applications in lattice
QCD. In this talk, some recent and possible future uses of the flow are
discussed, emphasizing the underlying theoretical concepts rather than any
computational aspects.


title: Why Gauge?

abstract:
  The world appears to be well described by gauge theories; why? I suggest that
gauge is more than mathematical redundancy. Gauge-dependent quantities can not
be predicted, but there is a sense in which they can be measured. They describe
"handles" though which systems couple: they represent real relational
structures to which the experimentalist has access in measurement by supplying
one of the relata in the measurement procedure itself. This observation leads
to a physical interpretation for the ubiquity of gauge: it is a consequence of
a relational structure of physical quantities.


title: Universality in mean curvature flow neckpinches

abstract:
  We study noncompact surfaces evolving by mean curvature flow. Without any
symmetry assumptions, we prove that any solution that is $C^3$-close at some
time to a standard neck will develop a neckpinch singularity in finite time,
will become asymptotically rotationally symmetric in a space-time neighborhood
of its singular set, and will have a unique tangent flow.


title:
Emergent Kinetics and Fractionalized Charge in 1D Spin-Orbit Coupled
  Flatband Optical Lattices

abstract:
  Recent ultracold atomic gas experiments implementing synthetic spin-orbit
coupling allow access to flatbands that emphasize interactions. We model
spin-orbit coupled fermions in a one-dimensional flatband optical lattice. We
introduce an effective Luttinger-liquid theory to show that interactions
generate collective excitations with emergent kinetics and fractionalized
charge, analogous to properties found in the two-dimensional fractional quantum
Hall regime. Observation of these excitations would provide an important
platform for exploring exotic quantum states derived solely from interactions.


title:
Reversible redox reactions in an epitaxially stabilized SrCoOx oxygen
  sponge

abstract:
  Fast, reversible redox reactions in solids at low temperatures without
thermomechanical degradation are a promising strategy for enhancing the overall
performance and lifetime of many energy materials and devices. However, the
robust nature of the cation's oxidation state and the high thermodynamic
barrier have hindered the realization of fast catalysis and bulk diffusion at
low temperatures. Here, we report a significant lowering of the redox
temperature by epitaxial stabilization of strontium cobaltites (SrCoOx) grown
directly as one of two distinct crystalline phases, either the perovskite
SrCoO3-{\delta} or the brownmillerite SrCoO2.5. Importantly, these two phases
can be reversibly switched at a remarkably reduced temperature (200~300
{\deg}C) in a considerably short time (< 1 min) without destroying the parent
framework. The fast, low temperature redox activity in SrCoO3-{\delta} is
attributed to a small Gibbs free energy difference between two topotatic
phases. Our findings thus provide useful information for developing highly
sensitive electrochemical sensors and low temperature cathode materials.


title: Neighborhoods of subvarieties in homogeneous spaces

abstract:
  We study the holomorphic/meromorphic function theory and the fundamental
group of Euclidean open neighborhoods of compact subvarieties in homogeneous
spaces; building on results of Hironaka, Hartshorne, Napier and Ramachandran in
the ample normal bundle case.


title:
Quantum probabilities of composite events in quantum measurements with
  multimode states

abstract:
  The problem of defining quantum probabilities of composite events is
considered. This problem is of high importance for the theory of quantum
measurements and for quantum decision theory that is a part of measurement
theory. We show that the Luders probability of consecutive measurements is a
transition probability between two quantum states and that this probability
cannot be treated as a quantum extension of the classical conditional
probability. The Wigner distribution is shown to be a weighted transition
probability that cannot be accepted as a quantum extension of the classical
joint probability. We suggest the definition of quantum joint probabilities by
introducing composite events in multichannel measurements. The notion of
measurements under uncertainty is defined. We demonstrate that the necessary
condition for the mode interference is the entanglement of the composite
prospect together with the entanglement of the composite statistical state. As
an illustration, we consider an example of a quantum game. A special attention
is payed to the application of the approach to systems with multimode states,
such as atoms, molecules, quantum dots, or trapped Bose-condensed atoms with
several coherent modes.


title:
Complete Nagy-Soper subtraction for next-to-leading order calculations
  in QCD

abstract:
  We extend the Helac-Dipoles package with the implementation of a new
subtraction formalism, first introduced by Nagy and Soper in the formulation of
an improved parton shower. We discuss a systematic, semi-numerical approach for
the evaluation of the integrated subtraction terms for both massless and
massive partons, which provides the missing ingredient for a complete
implementation. In consequence, the new scheme can now be used as part of a
complete NLO QCD calculation for processes with arbitrary parton masses and
multiplicities. We assess its overall performance through a detailed comparison
with results based on Catani-Seymour subtraction. The importance of random
polarization and color sampling of the external partons is also examined.


title:
Central Limit Theorem and exponential tail estimations in mixed
  (anisotropic) Lebesgue spaces

abstract:
  We study the Central Limit Theorem (CLT) in the so-called mixed (anisotropic)
Lebesgue-Riesz spaces and tail behavior of normed sums of centered random
independent variables (vectors) with values in these spaces.


title:
Topological Crystalline Kondo Insulator in Mixed Valence Ytterbium
  Borides

abstract:
  The electronic structures of two mixed valence insulators YbB$_6$ and
YbB$_12$ are studied by using the local density approximation (LDA)
supplemented with the Gutzwiller method and dynamic mean field theory (DMFT).
YbB$_6$ is found to be a moderately correlated Z$_2$ topological insulator,
similar to SmB$_6$ but having much larger bulk band gap. Notably, YbB$_12$ is
revealed to be in a new novel quantum state, strongly correlated topological
crystalline Kondo insulator, which is characterized by its non-zero mirror
Chern number. The surface calculations find odd (three) and even (four) number
of Dirac cones for YbB$_6$ and YbB$_12$, respectively.


title: Implicit Resolution

abstract:
  Let \Omega be a set of unsatisfiable clauses, an implicit resolution
refutation of \Omega is a circuit \beta with a resolution proof {\alpha} of the
statement "\beta describes a correct tree-like resolution refutation of
\Omega". We show that such system is p-equivalent to Extended Frege. More
generally, let {\tau} be a tautology, a [P, Q]-proof of {\tau} is a pair
(\alpha,\beta) s.t. \alpha is a P-proof of the statement "\beta is a circuit
describing a correct Q-proof of \tau". We prove that [EF,P] \leq p [R,P] for
arbitrary Cook-Reckhow proof system P.


title:
Frequency Recognition in SSVEP-based BCI using Multiset Canonical
  Correlation Analysis

abstract:
  Canonical correlation analysis (CCA) has been one of the most popular methods
for frequency recognition in steady-state visual evoked potential (SSVEP)-based
brain-computer interfaces (BCIs). Despite its efficiency, a potential problem
is that using pre-constructed sine-cosine waves as the required reference
signals in the CCA method often does not result in the optimal recognition
accuracy due to their lack of features from the real EEG data. To address this
problem, this study proposes a novel method based on multiset canonical
correlation analysis (MsetCCA) to optimize the reference signals used in the
CCA method for SSVEP frequency recognition. The MsetCCA method learns multiple
linear transforms that implement joint spatial filtering to maximize the
overall correlation among canonical variates, and hence extracts SSVEP common
features from multiple sets of EEG data recorded at the same stimulus
frequency. The optimized reference signals are formed by combination of the
common features and completely based on training data. Experimental study with
EEG data from ten healthy subjects demonstrates that the MsetCCA method
improves the recognition accuracy of SSVEP frequency in comparison with the CCA
method and other two competing methods (multiway CCA (MwayCCA) and phase
constrained CCA (PCCA)), especially for a small number of channels and a short
time window length. The superiority indicates that the proposed MsetCCA method
is a new promising candidate for frequency recognition in SSVEP-based BCIs.


title:
Structural properties and phase diagram of the $La(Fe_{1-x}Ru_x)AsO$
  system

abstract:
  Structural refinement, lattice microstrain and spontaneous strain analyses
have been carried out and a phase diagram has been drawn.


title:
Discovery of periodic modulations in the optical spectra of galaxies,
  possibly due to ultra-rapid light bursts from their massive central black
  hole

abstract:
  A Fourier transform analysis of 2.5 million spectra in the SDSS survey was
carried out to detect periodic modulations contained in their intensity versus
frequency spectrum. A statistically significant signal was found for 223
galaxies while the spectra of 0.9 million galaxies were observed. A plot of the
periods as a function of redshift clearly shows that the effect is real without
any doubt, because they are quantized at two base periods that increase with
redshift in two very tight parallel linear relations. I suggest that it could
be caused by light bursts separated by times of the order of 10-13 seconds
because it was the original reason for searching for the spectral periodicity
but other causes may be possible. As another possible cause, I investigate the
hypothesis that the modulation is generated by the Fourier transform of
spectral lines, concluding that it is not valid. Although the light bursts
suggestion implies absurdly high temperatures, it is supported by the fact that
the Crab pulsar also has extremely short unresolved pulses (<0.5 nanosecond)
that also imply absurdly high temperatures. Furthermore, the radio spectrum of
the Crab pulsar also has spectral bands similar to those that have been
detected. Finally, decreasing the signal to noise threshold of detection gave
results consistent with beamed signals having a small beam divergence, as
expected from non-thermal sources that send a jet, like those seen in pulsars.
Considering that galaxy centers contain massive black holes, exotic black hole
physics may be responsible for the spectral modulation. However, at this stage,
this is only a hypothesis to be confirmed with further work.


title:
Maximizers for Gagliardo-Nirenberg inequalities and related non-local
  problems

abstract:
  In this paper we study the existence of maximizers for two families of
interpolation inequalities, namely a generalized Gagliardo-Nirenberg inequality
and a new inequality involving the Riesz energy. Two basic tools in our
argument are a generalization of Lieb's Translation Lemma and a Riesz energy
version of the Br\'ezis--Lieb lemma.


title: The frenetic origin of negative differential response

abstract:
  The Green-Kubo formula for linear response coefficients gets modified when
dealing with nonequilibrium dynamics. In particular negative differential
conductivities are allowed to exist away from equilibrium. We give a unifying
framework for such negative differential response in terms of the frenetic
contribution in the nonequilibrium formula. It corresponds to a negative
dependence of the escape rates and reactivities on the driving forces. Partial
caging in state space and reduction of dynamical activity with increased
driving cause the current to drop. These are time-symmetric kinetic effects
that are believed to play a major role in the study of nonequilibria. We give
various simple examples treating particle and energy transport, which all
follow the same pattern in the dependence of the dynamical activity on the
nonequilibrium driving, made visible from recently derived nonequilibrium
response theory.


title: Quantum Noise Filtering via Cross-Correlations

abstract:
  Motivated by successful classical models for noise reduction, we suggest a
quantum technique for filtering noise out of quantum states. The purpose of
this paper is twofold: presenting a simple construction of quantum
cross-correlations between two wave-functions, and presenting a scheme for a
quantum noise filtering. We follow a well-known scheme in classical
communication theory that attenuates random noise, and show that one can build
a quantum analog by using non-trace-preserving operators. By this we introduce
a classically motivated signal processing scheme to quantum information theory,
which can help reducing quantum noise, and particularly, phase flip noise.


title: Turning a Band Insulator Into an Exotic Superconductor

abstract:
  Understanding exotic, non s--wave--like states of Cooper pairs is important
and may lead to new superconductors with higher critical temperatures and novel
properties. Their existence is known to be possible but has always been thought
to be associated with non--traditional mechanisms of superconductivity where
electronic correlations play an important role. Here we use a first principles
linear response calculation to show that in doped Bi$_{2}$Se$_{3}$ an
unconventional p--wave--like state can be favored via a conventional
phonon--mediated mechanism, as driven by an unusual, almost singular behavior
of the electron--phonon interaction at long wavelengths. This may provide a new
platform for our understanding superconductivity phenomena in doped band
insulators.


title:
Raman spectroscopy study of the interface structure in
  (CaCuO2)n/(SrTiO3)m superlattices

abstract:
  Raman spectra of CaCuO2/SrTiO3 superlattices show clear spectroscopic marker
of two structures formed in CaCuO2 at the interface with SrTiO3. For
non-superconducting superlattices, grown in low oxidizing atmosphere, the 425
cm-1 frequency of oxygen vibration in CuO2 planes is the same as for CCO films
with infinite layer structure (planar Cu-O coordination). For superconducting
superlattices grown in highly oxidizing atmosphere, a 60 cm-1 frequency shift
to lower energy occurs. This is ascribed to a change from planar to pyramidal
Cu-O coordination because of oxygen incorporation at the interface. Raman
spectroscopy proves to be a powerful tool for interface structure
investigation.


title:
A deep quench approach to the optimal control of an Allen-Cahn equation
  with dynamic boundary condition and double obstacle potentials

abstract:
  In this paper, we investigate optimal control problems for Allen-Cahn
variational inequalities with a dynamic boundary condition involving double
obstacle potentials and the Laplace-Beltrami operator. The approach covers both
the cases of distributed controls and of boundary controls. The cost functional
is of standard tracking type, and box constraints for the controls are
prescribed. We prove existence of optimal controls and derive first-order
necessary conditions of optimality. The general strategy is the following: we
use the results that were recently established by two of the authors for the
case of (differentiable) logarithmic potentials and perform a so-called "deep
quench limit". Using compactness and monotonicity arguments, it is shown that
this strategy leads to the desired first-order necessary optimality conditions
for the case of (non-differentiable) double obstacle potentials.


title: Notes on sets of first return

abstract:
  We prove in this note that, for an alphabet with three letters, the set of
first return to a given word in a set satisfying the tree condition is a basis
of the free group.


title:
Shut up and let me think. Or why you should work on the foundations of
  quantum mechanics as much as you please

abstract:
  If you have a restless intellect, it is very likely that you have played at
some point with the idea of investigating the meaning and conceptual
foundations of quantum mechanics. It is also probable (albeit not certain) that
your intentions have been stopped on their tracks by an encounter with some
version of the "Shut up and calculate" command. You may have heard that
everything is already understood. That understanding is not your job. Or, if it
is, it is either impossible or very difficult. Maybe somebody explained to you
that physics is concerned with "hows" and not with "whys"; that whys are the
business of "philosophy" ---you know, that dirty word. That what you call
"understanding" is just being Newtonian; which of course you cannot ask quantum
mechanics to be. Perhaps they also added some norms: The important thing a
theory must do is predict; a theory must only talk about measurable quantities.
It may also be the case that you almost asked "OK, and why is that?", but you
finally bit your tongue. If you persisted in your intentions and the debate got
a little heated up, it is even possible that it was suggested that you suffered
of some type of moral or epistemic weakness that tend to disappear as you grow
up. Maybe you received some job advice such as "Don't work in that if you ever
want to own a house".
  I have certainly met all these objections in my short career, and I think
that they are all just wrong. In this somewhat personal document, I try to
defend that making sense of quantum mechanics is an exciting, challenging,
important and open scientific endeavor. I do this by compulsively quoting
Feynman (and others), and I provide some arguments that you might want to use
the next time you confront the mentioned "opinions". By analogy with the
anti-rationalistic Copenhagen command, all the arguments are subsumed in a
standard answer to it: "Shut up and let me think"


title: Few distinct distances implies no heavy lines or circles

abstract:
  We study the structure of planar point sets that determine a small number of
distinct distances. Specifically, we show that if a set P of n points
determines o(n) distinct distances, then no line contains \Omega(n^{7/8})
points of P and no circle contains \Omega(n^{5/6}) points of P.
  We rely on the bipartite and partial variant of the Elekes-Sharir framework
that was presented by Sharir, Sheffer, and Solymosi in \cite{SSS13}. For the
case of lines we combine this framework with a theorem from additive
combinatorics, and for the case of circles we combine it with some basic
algebraic geometry and a recent incidence bound for plane algebraic curves by
Wang, Yang, and Zhang \cite{WYZ13}. A significant difference between our
approach and that of \cite{SSS13} (and other recent extensions) is that,
instead of dealing with distances between two point sets that are restricted to
one-dimensional curves, we consider distances between one set that is
restricted to a curve and one set with no restrictions on it.


title: Spin relaxation via exchange with donor impurity-bound electrons

abstract:
  At low temperatures, electrons in semiconductors are bound to shallow donor
impurity ions, neutralizing their charge in equilibrium. Inelastic scattering
of other externally-injected conduction electrons accelerated by electric
fields can excite transitions within the manifold of these localized states.
Promotion of the bound electron into highly spin-orbit-mixed excited states
drives a strong spin relaxation of the conduction electrons via exchange
interactions, reminiscent of the Bir-Aronov-Pikus process where exchange occurs
with valence band hole states. Through low-temperature experiments with silicon
spin transport devices and complementary theory, we reveal the consequences of
this previously unknown spin depolarization mechanism both below and above the
impact ionization threshold.


title:
A recurrence-based technique for detecting genuine extremes in
  instrumental temperature records

abstract:
  In this paper, we analyze several instrumental records of temperatures at
different locations by using new techniques originally developed for the
analysis of extreme values of dynamical systems. We show that they have the
same recurrence time statistics as a chaotic dynamical system perturbed with
dynamical noise and by instrument errors. The technique provides a criterion to
discriminate whether the recurrence of a certain temperature belongs to the
normal variability or can be considered as a genuine extreme event with respect
to a specific timescale fixed as parameter. The method gives a self-consistent
estimation of the convergence of the statistics of recurrences toward the
theoretical extreme value laws.


title: One-step estimator paths for concave regularization

abstract:
  The statistics literature of the past 15 years has established many favorable
properties for sparse diminishing-bias regularization: techniques which can
roughly be understood as providing estimation under penalty functions spanning
the range of concavity between $L_0$ and $L_1$ norms. However, lasso
$L_1$-regularized estimation remains the standard tool for industrial `Big
Data' applications because of its minimal computational cost and the presence
of easy-to-apply rules for penalty selection. In response, this article
proposes a simple new algorithm framework that requires no more computation
than a lasso path: the path of one-step estimators (POSE) does $L_1$ penalized
regression estimation on a grid of decreasing penalties, but adapts
coefficient-specific weights to decrease as a function of the coefficient
estimated in the previous path step. This provides sparse diminishing-bias
regularization at no extra cost over the fastest lasso algorithms. Moreover,
our `gamma lasso' implementation of POSE is accompanied by a reliable heuristic
for the fit degrees of freedom, so that standard information criteria can be
applied in penalty selection. We also provide novel results on the distance
between weighted-$L_1$ and $L_0$ penalized predictors; this allows us to build
intuition about POSE and other diminishing-bias regularization schemes. The
methods and results are illustrated in extensive simulations and in application
of logistic regression to evaluating the performance of hockey players.


title: Extreme Value laws for dynamical systems under observational noise

abstract:
  In this paper we prove the existence of Extreme Value Laws for dynamical
systems perturbed by instrument-like-error, also called observational noise. An
orbit perturbed with observational noise mimics the behavior of an
instrumentally recorded time series. Instrument characteristics - defined as
precision and accuracy - act both by truncating and randomly displacing the
real value of a measured observable. Here we analyze both these effects from a
theoretical and numerical point of view. First we show that classical extreme
value laws can be found for orbits of dynamical systems perturbed with
observational noise. Then we present numerical experiments to support the
theoretical findings and give an indication of the order of magnitude of the
instrumental perturbations which cause relevant deviations from the extreme
value laws observed in deterministic dynamical systems. Finally, we show that
the observational noise preserves the structure of the deterministic attractor.
This goes against the common assumption that random transformations cause the
orbits asymptotically fill the ambient space with a loss of information about
any fractal structures present on the attractor.


title: Shape identification and classification in echolocation

abstract:
  The paper aims at proposing the first shape identification and classification
algorithm in echolocation. The approach is based on first extracting geometric
features from the reflected waves and then matching them with precomputed ones
associated with a dictionary of targets. The construction of such
frequency-dependent shape descriptors is based on some important properties of
the scattering coefficients and new invariants. The stability and resolution of
the proposed identification algorithm with respect to measurement noise and the
limited-view aspect are analytically and numerically quantified.


title:
A Progressive Statistical Method for Preconditioning Matrix-Free
  Solution of High-Order Discretization of Linear Time-Dependent Problems

abstract:
  Preconditioning of a linear system obtained from spectral discretization of
time-dependent PDEs often results in a full matrix which is expensive to
compute and store specially when the problem size increases. A matrix-free
implementation is usually applied to resolve this issue. In this framework,
preconditioning is typically challenging since the entries of the matrix are
not explicitly available. In this short note, we propose a statistical approach
to gradually create a preconditioner matrix by collecting the information
obtained from matrix-vector product in the Arnoldi loop of an unpreconditioned
Krylov subspace algorithm. The gathered information are then correlated using a
multiple regressors estimate where the error is assumed to be normally
distributed. This procedure yields a banded diagonal matrix which is then used
as a preconditioner in the next iterative solve. This is repeated between
iterative solves until a good preconditioner is constructed on fly. This
statistically iterative procedure is progressive since the fidelity of the
preconditioning matrix improves by adding more data obtained from matrix-vector
product during the entire solution procedure. The proposed algorithm is
validated for a sample implementation.


title:
The tension on the cosmological parameters from different observational
  data

abstract:
  Planck measurements of the cosmic microwave background power spectra find a
lower value of the Hubble constant $H_0$ and a higher value of the fractional
matter energy density $\Omega_{m0}$ for the concordance $\Lambda$CDM model, and
these results are in tension with other measurements. The {\em Planck} group
argued that the tension came either from some sources of unknown systematic
errors in some astrophysical measurements or the wrong $\Lambda$CDM model
applied in fitting the data. We studied the reason for the tension on $H_0$
from different measurements by considering two dynamical dark energy models. We
found that there is no tension between different data, the constraint on $H_0$
is almost unchanged for different dark energy models and the tension with the
local measurements remains when the error bar on $H_0$ is tightened to be
around 1. We argue that the tension on $H_0$ is not caused by the fitting
model.


title: 2-elementary subgroups of the space Cremona group

abstract:
  We give a sharp bound for orders of elementary abelian 2-groups of birational
automorphisms of rationally connected threefolds.


title: Approximate solution to the stochastic Kuramoto model

abstract:
  We study Kuramoto phase oscillators with temporal fluctuations in the
frequencies. The infinite-dimensional system can be reduced in a Gaussian
approximation to two first-order differential equations. This yields a solution
for the \emph{time-dependent} order parameter, which characterizes the
synchronization between the oscillators. The known critical coupling strength
is exactly recovered by the Gaussian theory. Extensive numerical experiments
further show that the analytical results are very accurate below and
sufficiently above the critical value. We obtain the asymptotic order parameter
\emph{in closed form}, which suggests a tighter upper bound for the
corresponding scaling. As a last point, we elaborate the Gaussian approximation
in complex networks with distributed degrees.


title: Quantum gravity effects in Myers-Perry space-times

abstract:
  We study quantum gravity effects for Myers-Perry black holes assuming that
the leading contributions arise from the renormalization group evolution of
Newton's coupling. Provided that gravity weakens following the asymptotic
safety conjecture, we find that quantum effects lift a degeneracy of
higher-dimensional black holes, and dominate over kinematical ones induced by
rotation, particularly for small black hole mass, large angular momentum, and
higher space-time dimensionality. Quantum-corrected space-times display inner
and outer horizons, and show the existence of a black hole of smallest mass in
any dimension. Ultra-spinning solutions no longer persist. Thermodynamic
properties including temperature, specific heat, the Komar integrals, and
aspects of black hole mechanics are studied as well. Observing a softening of
the ring singularity, we also discuss the validity of classical energy
conditions.


title: Replicator equations and space

abstract:
  A reaction--diffusion replicator equation is studied. A novel method to apply
the principle of global regulation is used to write down the model with
explicit spatial structure. Properties of stationary solutions together with
their stability are analyzed analytically, and relationships between stability
of the rest points of the non-distributed replicator equation and distributed
system are shown. A numerical example is given to show that the spatial
variable in this particular model promotes the system's permanence.


title:
Colloids in light fields: particle dynamics in random and periodic
  energy landscapes

abstract:
  The dynamics of colloidal particles in potential energy landscapes have
mainly been investigated theoretically. In contrast, here we discuss the
experimental realization of potential energy landscapes with the help of light
fields and the observation of the particle dynamics by video microscopy. The
experimentally observed dynamics in periodic and random potentials are compared
to simulation and theoretical results in terms of, e.g. the mean-squared
displacement, the time-dependent diffusion coefficient or the non-Gaussian
parameter. The dynamics are initially diffusive followed by intermediate
subdiffusive behaviour which again becomes diffusive at long times. How
pronounced and extended the different regimes are, depends on the specific
conditions, in particular the shape of the potential as well as its roughness
or amplitude but also the particle concentration. Here we focus on dilute
systems, but the dynamics of interacting systems in external potentials, and
thus the interplay between particle-particle and particle-potential
interactions, is also mentioned briefly. Furthermore, the observed dynamics of
dilute systems resemble the dynamics of concentrated systems close to their
glass transition, with which it is compared. The effect of certain potential
energy landscapes on the dynamics of individual particles appears similar to
the effect of interparticle interactions in the absence of an external
potential.


title: Maximal regularity of the time-periodic Navier-Stokes system

abstract:
  Time-periodic solutions to the linearized Navier-Stokes system in the
$n$-dimensional whole-space are investigated. For time-periodic data in
$L^q$-spaces, maximal regularity and corresponding a priori estimates for the
associated time-periodic solutions are established. More specifically, a Banach
space of time-periodic vector fields is identified with the property that the
linearized Navier-Stokes operator maps this space homeomorphically onto the
$L^q$-space of time-periodic data.


title: Probing $tt\gamma$ and $ttZ$ couplings at the LHeC

abstract:
  We study the deep inelastic scattering and photo-production modes of
$t\overline{t}$ pairs at the proposed LHeC and its potential to probe the
electromagnetic and weak dipole moments (MDM and EDM for $tt\gamma$) of the top
quark. A framework of eight independent gauge-invariant dimension-six operators
involving the top quark and the electroweak gauge bosons is used. Four of these
operators modify the charged $tbW$ coupling which can be probed through the
single (anti) top production mode as reported in the literature. One generates
$tt\gamma (Z)$ as well as $tbW$ couplings, while the other two do not generate
$tbW$ but only $tt\gamma (Z)$. Our focus is on the MDM and EDM of the top quark
for which the photo-production mode of $t\overline{t}$ can be an excellent
probe. At the proposed electron energies of $E_e =60$ and $140$ GeV the LHeC
could set constraints stronger than the indirect limits from $b\to s \gamma$
and the potential limits of the LHC through $t\overline{t} \gamma$ production.


title: Edge States: Topological Insulators, Superconductors and QCD Chiral Bags

abstract:
  The dynamics of the magnetic field in a superconducting phase is described by
an effective massive bosonic field theory. If the superconductor is confined in
a domain M with boundary \partial M, the boundary conditions of the
electromagnetic fields are predetermined by physics. They are time-reversal and
also parity invariant for adapted geometry. They lead to edge excitations while
in comparison, the bulk energies have a large gap. A similar phenomenon occurs
for topological insulators where appropriate boundary conditions for the Dirac
Hamiltonian also lead to similar edge states and an 'incompressible bulk'. They
give spin-momentum locking as well. In addition time-reversal and parity
invariance emerge for adapted geometry. Similar edge states appear in QCD bag
models with chiral boundary conditions.


title: Bayesian model selection for dark energy using weak lensing forecasts

abstract:
  The next generation of weak lensing probes can place strong constraints on
cosmological parameters by measuring the mass distribution and geometry of the
low redshift universe. We show that a future all-sky tomographic cosmic shear
survey with design properties similar to Euclid can provide the statistical
accuracy required to distinguish between different dark energy models. Using a
fiducial cosmological model which includes cold dark matter, baryons, massive
neutrinos (hot dark matter), a running primordial spectral index and possible
spatial curvature as well as dark energy perturbations, we calculate Fisher
matrix forecasts for different dynamical dark energy models. Using a Bayesian
evidence calculation we show how well a future weak lensing survey could do in
distinguishing between a cosmological constant and dynamical dark energy.


title:
Gravitational Infall onto Molecular Filaments II. Externally Pressurized
  Cylinders

abstract:
  In an extension of Fischera & Martin (2012a) and Heitsch (2013), two aspects
of the evolution of externally pressurized, hydrostatic filaments are
discussed. (a) The free-fall accretion of gas onto such a filament will lead to
filament parameters (specifically, FWHM--column density relations) inconsistent
with the observations of Arzoumanian et al. (2011), except for two cases: For
low-mass, isothermal filaments, agreement is found as in the analysis by
Fischera & Martin (2012b). Magnetized cases, for which the field scales weakly
with the density as $B\propto n^{1/2}$, also reproduce observed parameters. (b)
Realistically, the filaments will be embedded not only in gas of non-zero
pressure, but also of non-zero density. Thus, the appearance of sheet-embedded
filaments is explored. Generating a grid of filament models and comparing the
resulting column density ratios and profile shapes with observations suggests
that the three-dimensional filament profiles are intrinsically flatter than
isothermal, beyond projection and evolution effects.


title: Splitting numbers of links

abstract:
  The splitting number of a link is the minimal number of crossing changes
between different components required, on any diagram, to convert it to a split
link. We introduce new techniques to compute the splitting number, involving
covering links and Alexander invariants. As an application, we completely
determine the splitting numbers of links with 9 or fewer crossings. Also, with
these techniques, we either reprove or improve upon the lower bounds for
splitting numbers of links computed by J. Batson and C. Seed using Khovanov
homology.


title:
Charge state distribution analysis of Al and Pb ions from the laser ion
  source at IMP

abstract:
  A prototype laser ion source that could demonstrate the possibility of
producing intense pulsed high charge state ion beams has been established with
a commercial Nd:YAG laser (E max = 3 J, 1064 nm, 8-10 ns) to produce laser
plasma for the research of Laser Ion Source (LIS). At the laser ion source test
bench, high purity (99.998 %) aluminum and lead targets have been tested for
laser plasma experiment. An Electrostatic Ion Analyzer (EIA) and Electron
Multiply Tube (EMT) detector were used to analyze the charge state and energy
distribution of the ions produced by the laser ion source. The maximum charge
states of Al12+ and Pb7+ were achieved. The results will be presented and
discussed in this paper.


title: Quantum criticality and dynamical instability in the kicked top

abstract:
  We investigate precursors of critical behavior in the quasienergy spectrum
due to the dynamical instability in the kicked top. Using a semiclassical
approach, we analytically obtain a logarithmic divergence in the density of
states, which is analogous to a continuous excited state quantum phase
transition in undriven systems. We propose a protocol to observe the cusp
behavior of the magnetization close to the critical quasienergy.


title: Search for new Physics with the $\pi\rightarrow e\nu$ Decay

abstract:
  In the Standard Model, lepton universality refers to the identical
electroweak gauge interactions among charged leptons. The measurement of the
branching ratio $R_{e / \mu} = \frac{\Gamma(\pi\rightarrow\ e
\nu)}{\Gamma(\pi\rightarrow\mu\nu)}$ is one of the most stringent tests of
lepton universality between the first two generations. The TRIUMF PIENU
experiment aims at the most precise test of universality measuring $R_{e /
\mu}$ with 0.1% precision. The measurement will provide improved constraints to
physics beyond the Standard Model or uncover new scenarios if a disagreement is
found.


title:
Sulfur annealing effect for superconductivity in iron chalcogenide
  compounds

abstract:
  We discovered a novel annealing method for Fe-chalcogenide superconductors.
It was found that sulfur annealing deintercalated excess Fe via formation of
FeS2. Due to its specifics, sulfur annealing is applicable when preparing
Fe-chalcogenide-based wires or cables.


title:
Green's function for certain domains in the Heisenberg Group $\mathbb
  H_n$

abstract:
  We obtain explicit smooth Green's functions for annular domain and infinite
strip by using kelvin $R$-transform in the Heisenberg group $\H_n$.


title: Off-diagonal decay of Bergman kernels: On a conjecture of Zelditch

abstract:
  Consider a complex line bundle over a compact complex manifold equipped with
an infinitely differentiable metric with strictly positive curvature form.
Assign to positive tensor powers of this bundle the associated product metrics
and Bergman projection operators. Zelditch has conjectured that if the Bergman
kernels, away from the diagonal, decay exponentially fast to zero as the power
tends to infinity, then the metric must be real analytic. Moreover, this is
conjectured even if exponential decay is assumed to hold merely for some
arbitrarily sparse subsequence of powers tending to infinity.
  Previously the author has constructed examples in which the metric is
infinitely differentiable, but exponential decay does not hold. These examples
are within a framework in which a certain degree of symmetry is present. In the
present paper we prove the conjecture for all structures within this framework,
thus providing evidence in favor of the conjecture. The analysis is carried out
for base manifolds of arbitrary dimensions, rather than only for dimension one
as in the author's previous work.


title: Model of deep non-volcanic tremor part I: ambient and triggered tremor

abstract:
  There is evidence of triggering of tremor by seismic waves emanating from
distant large earthquakes. The frequency contents of triggered and ambient
tremor are largely identical, suggesting that tremor does not depend directly
on the nature of the source. We show here that the model of plate dynamics
developed earlier by us is an appropriate tool for describing the onset of
tremor. In the framework of this model, tremor is an internal response of a
fault to a failure triggered by external disturbances. The model predicts
generation of radiation in a frequency range defined by the fault parameters.
Other specific features predicted are: the upper limit of the size of the
emitting area is a few dozen km; tremor accompanies earthquakes and aseismic
slip; the frequency content of tremor depends on the type of failure. The model
also explains why a tremor has no clear impulsive phase, in contrast to
earthquakes. A comparatively small effective normal stress (hence a high fluid
pressure) is required to make the model consistent with observed tremor
parameters. Our model indicates that tremor is not necessarily a superposition
of low frequency earthquakes, as commonly assumed, although the latter may
trigger them. The approach developed complements the conventional viewpoint
which assumes that tremor reflects a frictional process with low rupture speed.
Essentially our model adds the hypothesis that resonant-type oscillations exist
inside a fault. This addition may change our understanding of the nature of
tremor in general, and the methods of its identification and location in
particular.


title:
Experimental Demonstration of Energy Chirp Compensation by a Tunable
  Dielectric Based Structure

abstract:
  A 60 MeV beam at the BNL Accelerator Test Facility (ATF) was manipulated by a
planar tunable de-chirper made out of two 10 cm long dielectric slabs with
copper plated backs. While the gap was changed from 5.8 mm to 1 mm, the
correlated energy chirp of the low charge electron bunch was reduced from
approximately 330 keV/mm to zero. This result is in agreement with simulations.
Calculations show that similar devices, properly scaled to account for the
expected electron bunch charge and length, can be used to remove residual
correlated energy spread at the end of the linacs used for free-electron lasers
(FEL). Potentially, this technique could significantly simplify linac design
and improve FEL performance.


title:
Electrical transport properties of small diameter single-walled carbon
  nanotubes aligned on ST-cut quartz substrates

abstract:
  A method is introduced to isolate and measure the electrical transport
properties of individual single-walled carbon nanotubes (SWNTs) aligned on an
ST-cut quartz, from room temperature down to 2 K. The diameter and chirality of
the measured SWNTs are accurately defined from Raman spectroscopy and atomic
force microscopy (AFM). A significant up-shift in the G-band of the resonance
Raman spectra of the SWNTs is observed, which increases with increasing SWNTs
diameter, and indicates a strong interaction with the quartz substrate. A
semiconducting SWNT, with diameter 0.84 nm, shows Tomonaga-Luttinger liquid and
Coulomb blockade behaviors at low temperatures. Another semiconducting SWNT,
with a thinner diameter of 0.68 nm, exhibits a transition from the
semiconducting state to an insulating state at low temperatures. These results
elucidate some of the electrical properties of SWNTs in this unique
configuration and help pave the way towards prospective device applications.


title:
Semiclassical states in quantum gravity: Curvature associated to a
  Voronoi graph

abstract:
  The building blocks of a quantum theory of general relativity are expected to
be discrete structures. Loop quantum gravity is formulated using a basis of
spin networks (wave functions over oriented graphs with coloured edges), thus
realizing the aforementioned expectation. Semiclassical states should, however,
reproduce the classical smooth geometry in the appropriate limits. The question
of how to recover a continuous geometry from these discrete structures is,
therefore, relevant in this context. Following previous works by Bombelli et
al. we explore this problem from a rather general mathematical perspective
using, in particular, properties of Voronoi graphs to search for their
compatible continuous geometries. We test the previously proposed methods for
computing the curvature associated to such graphs and analyse the framework in
detail, in the light of the results obtained.


title: Traveling Wave Solutions of Degenerate Coupled KdV Equation

abstract:
  We give a detailed study of the traveling wave solutions of $(\ell=2)$
Kaup-Boussinesq type of coupled KdV equations. Depending upon the zeros of a
fourth degree polynomial, we have cases where there exist no nontrivial real
solutions, cases where asymptotically decaying to a constant solitary wave
solutions, and cases where there are periodic solutions. All such possible
solutions are given explicitly in the form of Jacobi elliptic functions. Graphs
of some exact solutions in solitary wave and periodic shapes are exhibited.
Extension of our study to the cases $\ell=3$ and $\ell=4$ are also mentioned.


title:
Beyond spectral homodyne detection: complete quantum measurement of
  spectral modes of light

abstract:
  Spectral homodyne detection, a widely used technique for measuring quantum
properties of light beams, cannot retrieve all the information needed to
reconstruct the quantum state of spectral field modes. We show that full
quantum state reconstruction can be achieved with the alternative measurement
technique of resonator detection. We experimentally demonstrate this difference
by engineering a quantum state with features that go undetected by homodyne
detection but are clearly revealed by resonator detection.


title: Are GRBs the same at high and low redshift?

abstract:
  Due to their highly luminous nature, gamma-ray bursts (GRBs) are useful tools
in studying the early Universe (up to z = 10). We consider whether the
available subset of Swift high redshift GRBs are unusual when compared to
analogous simulations of a bright low redshift sample. By simulating data from
the Burst Alert Telescope (BAT; Barthelmy et al. 2005) the light curves of
these bright bursts are obtained over an extensive range of redshifts,
revealing complicated evolution in properties of the prompt emission such as
T90.


title:
Synthesis and properties of Co-doped titanate nanotubes and their
  optical sensitization with methylene blue

abstract:
  Here we report on a novel chemical route to synthesize homogenous cobalt
doped titanate nanotubes (CoTNT), using an amorphous Co-doped precursor. The
influence of the synthesis temperature, autoclave dwell time and metal doping
on the structural and microstructural as well as on the optical properties of
the synthesized titanate nanotubes is studied and discussed. The optical band
gaps of the CoTNT samples are red shifted in comparison with the values
determined for the undoped samples, such red shifts bringing the absorption
edge of the CoTNT samples into the visible region. CoTNT materials also
demonstrate particular high adsorption ability for methylene blue, the amount
of the adsorbed dye being higher than the one predictable for a monolayer
formation. This suggests the possibility of intercalation of the dye molecule
between the TiO6 layers of the TNT structure. It is also shown that the
methylene blue sensitized Co-doped nanostructures are highly stable under UV
radiation and present a strong and broad absorption in the visible region.


title:
Cosmological Parameter Estimation from SN Ia data: a Model-Independent
  Approach

abstract:
  We perform a model independent reconstruction of the cosmic expansion rate
based on type Ia supernova data. Using the Union 2.1 data set, we show that the
Hubble parameter behaviour allowed by the data without making any hypothesis
about cosmological model or underlying gravity theory is consistent with a flat
LCDM universe having H_0 = 70.43 +- 0.33 and Omega_m=0.297 +- 0.020, weakly
dependent on the choice of initial scatter matrix. This is in closer agreement
with the recently released Planck results (H_0 = 67.3 +- 1.2, Omega_m = 0.314
+- 0.020) than other standard analyses based on type Ia supernova data. We
argue this might be an indication that, in order to tackle subtle deviations
from the standard cosmological model present in type Ia supernova data, it is
mandatory to go beyond parametrized approaches.


title: Search for cosmic-ray induced gamma-ray emission in Galaxy Clusters

abstract:
  Current theories predict relativistic hadronic particle populations in
clusters of galaxies in addition to the already observed relativistic leptons.
In these scenarios hadronic interactions give rise to neutral pions which decay
into $\gamma$ rays, that are potentially observable with the Large Area
Telescope (LAT) on board the Fermi space telescope. We present a joint
likelihood analysis searching for spatially extended $\gamma$-ray emission at
the locations of 50 galaxy clusters in 4 years of Fermi-LAT data under the
assumption of the universal cosmic-ray model proposed by Pinzke & Pfrommer
(2010). We find an excess at a significance of $2.7\sigma$ which upon closer
inspection is however correlated to individual excess emission towards three
galaxy clusters: Abell 400, Abell 1367 and Abell 3112. We discuss these cases
in detail and conservatively attribute the emission to unmodeled background
(for example, radio galaxies within the clusters). Through the combined
analysis of 50 clusters we exclude hadronic injection efficiencies in simple
hadronic models above 21% and establish limits on the cosmic-ray to thermal
pressure ratio within the virial radius, $R_{200}$, to be below 1.2-1.4%
depending on the morphological classification. In addition we derive new limits
on the $\gamma$-ray flux from individual clusters in our sample.


title:
Ultralow-power nonlinear optics using tapered optical fibers in
  metastable xenon

abstract:
  We demonstrate nanowatt-level saturated absorption using a sub-wavelength
diameter tapered optical fiber (TOF) suspended in a gas of metastable xenon
atoms. This ultralow-power nonlinearity is enabled by a small optical mode area
propagating over a relatively long distance through the Xe gas. The use of
inert noble gasses in these kinds of TOF experiments may offer practical
advantages over the use of reactive alkali vapors such as rubidium.


title: Exchange relation planar algebras of small rank

abstract:
  The main purpose of this paper is to classify exchange relation planar
algebras with 4 dimensional 2-boxes. Besides its skein theory, we emphasize the
positivity of subfactor planar algebras based on the Schur product theorem. We
will discuss the lattice of projections of 2-boxes, specifically the rank of
the projections. From this point, several results about biprojections are
obtained. The key break of the classification is to show the existence of a
biprojection. By this method, we also classify another two families of
subfactor planar algebras, subfactor planar algebras generated by 2-boxes with
4 dimensional 2-boxes and at most 23 dimensional 3-boxes; subfactor planar
algebras generated by 2-boxes, such that the quotient of 3-boxes by the basic
construction ideal is abelian. They extend the classification of singly
generated planar algebras obtained by Bisch, Jones and the author.


title: Rock-salt SnS and SnSe: Native Topological Crystalline Insulators

abstract:
  Unlike time-reversal topological insulators, surface metallic states with
Dirac cone dispersion in the recently discovered topological crystalline
insulators (TCIs) are protected by crystal symmetry. To date, TCI behaviors
have been observed in SnTe and the related alloys Pb$_{1-x}$Sn$_{x}$Se/Te,
which incorporate heavy elements with large spin-orbit coupling (SOC). Here, by
combining first-principles and {\it ab initio} tight-binding calculations, we
report the formation of a TCI in the relatively lighter rock-salt SnS and SnSe.
This TCI is characterized by an even number of Dirac cones at the high-symmetry
(001), (110) and (111) surfaces, which are protected by the reflection symmetry
with respect to the ($\bar{1}$10) mirror plane. We find that both SnS and SnSe
have an intrinsically inverted band structure and the SOC is necessary only to
open the bulk band gap. The bulk band gap evolution upon volume expansion
reveals a topological transition from an ambient pressure TCI to a
topologically trivial insulator. Our results indicate that the SOC alone is not
sufficient to drive the topological transition.