title:
Geospatial Narratives and their Spatio-Temporal Dynamics: Commonsense
  Reasoning for High-level Analyses in Geographic Information Systems

abstract:
  The modelling, analysis, and visualisation of dynamic geospatial phenomena
has been identified as a key developmental challenge for next-generation
Geographic Information Systems (GIS). In this context, the envisaged
paradigmatic extensions to contemporary foundational GIS technology raises
fundamental questions concerning the ontological, formal representational, and
(analytical) computational methods that would underlie their spatial
information theoretic underpinnings.
  We present the conceptual overview and architecture for the development of
high-level semantic and qualitative analytical capabilities for dynamic
geospatial domains. Building on formal methods in the areas of commonsense
reasoning, qualitative reasoning, spatial and temporal representation and
reasoning, reasoning about actions and change, and computational models of
narrative, we identify concrete theoretical and practical challenges that
accrue in the context of formal reasoning about `space, events, actions, and
change'. With this as a basis, and within the backdrop of an illustrated
scenario involving the spatio-temporal dynamics of urban narratives, we address
specific problems and solutions techniques chiefly involving `qualitative
abstraction', `data integration and spatial consistency', and `practical
geospatial abduction'. From a broad topical viewpoint, we propose that
next-generation dynamic GIS technology demands a transdisciplinary scientific
perspective that brings together Geography, Artificial Intelligence, and
Cognitive Science.
  Keywords: artificial intelligence; cognitive systems; human-computer
interaction; geographic information systems; spatio-temporal dynamics;
computational models of narrative; geospatial analysis; geospatial modelling;
ontology; qualitative spatial modelling and reasoning; spatial assistance
systems


title: Calibrated and parallel structures on almost Abelian Lie algebras

abstract:
  In this article, we determine the seven-dimensional almost Abelian Lie
algebras which admit calibrated or parallel G_2-/G_2^*-structures. Along the
way, we show that certain well-established curvature restrictions for
calibrated and parallel G_2-structures are not valid in the G_2^* case. In more
detail, we provide the first example of a Ricci-flat calibrated G_2^*-structure
on a compact manifold whose holonomy is not contained in G_2^*. Moreover, we
get examples of non-flat parallel G_2^*-structures on almost Abelian Lie
algebras g. We give a full classification of these G_2^*-structures if g is
additionally nilpotent.


title: Orbitron. Part II. Magnetic levitation

abstract:
  This paper devoted to proof the existence of stable quasi-periodic motions of
the magnetic dipole that is under the action of the external magnetic field and
homogeneous field of gravity. For proof this we used the group-theoretic
methods of Hamiltonian mechanics, viz energy-momentum method. Numerical
simulation shows the possibility of realization of stable motions with
physically reasonable parameters of the system.


title:
Complexity Reduction of Rate-Equations Models for Two-Choice
  Decision-Making

abstract:
  We are concerned with the complexity reduction of a stochastic system of
differential equations governing the dynamics of a neuronal circuit describing
a decision-making task. This reduction is based on the slow-fast behavior of
the problem and holds on the whole phase space and not only locally around the
spontaneous state. Macroscopic quantities, such as performance and reaction
times, computed applying this reduction are in agreement with previous works in
which the complexity reduction is locally performed at the spontaneous point by
means of a Taylor expansion.


title: A proof of Morse's theorem about the cancellation of critical points

abstract:
  In this note, we give a proof of the famous theorem of M. Morse dealing with
the cancellation of a pair of non-degenerate critical points of a smooth
function. Our proof consists of a reduction to the one-dimensional case where
the question becomes easy to answer.


title: Spectrum of periodically correlated fields

abstract:
  The paper deals with Hilbert space valued fields over any locally compact
Abelian group G, in particular over G = Z^n x R^m, which are periodically
correlated (PC) with respect to a closed subgroup of G. PC fields can be
regarded as multi-parameter extensions of PC processes. We study structure,
covariance function, and an analogue of the spectrum for such fields. As an
example a weakly PC field over Z^2 is thoroughly examined.


title: Homogenization of random parabolic operators. Diffusion approximation

abstract:
  The paper deals with homogenization of divergence form second order parabolic
operators whose coefficients are periodic in spatial variables and random
stationary in time. Under proper mixing assumptions, we study the limit
behaviour of the normalized difference between solutions of the original and
the homogenized problems. The asymptotic behaviour of this difference depends
crucially on the ratio between spatial and temporal scaling factors. Here we
study the case of self-similar parabolic diffusion scaling.


title:
A biomechanical modeling study of the effects of the orbicularis oris
  muscle and jaw posture on lip shape

abstract:
  Purpose: The authors' general aim is to use biomechanical models of speech
articulators to explore how possible variations in anatomical structure
contribute to differences in articulatory strategies and phone systems across
human populations. Specifically, they investigated 2 issues: (a) the link
between lip muscle anatomy and variability in lip gestures and (b) the
constraints of coupled lip/jaw biomechanics on jaw posture in labial sounds.
Method: The authors used a model coupling the jaw, tongue, and face. First, the
influence of the orbicularis oris (OO) anatomical implementation was analyzed
by assessing how changes in depth (from epidermis to the skull) and
peripheralness (proximity to the lip horn center) affected lip shaping. Second,
the capability of the lip/jaw system to generate protrusion and rounding, or
labial closure, was evaluated for different jaw heights. Results: Results
showed that a peripheral and moderately deep OO implementation is most
appropriate for protrusion and rounding; a superficial implementation
facilitates closure; protrusion and rounding require a high jaw position; and
closure is achievable for various jaw heights. Conclusions: Models provide
objective information regarding possible links between anatomical and speech
production variability across humans. Comparisons with experimental data will
illustrate how motor control and cultural factors cope with these constraints.


title:
Hamiltonicity of the Cayley Digraph on the Symmetric Group Generated by
  {\sigma} = (1 2 ... n) and {\tau} = (1 2)

abstract:
  The symmetric group is generated by {\sigma} = (1 2 ... n) and {\tau} = (1
2). We answer an open problem of Nijenhuis and Wilf by constructing a Hamilton
path in the directed Cayley graph for all n, and a Hamilton cycle for odd n.


title: Hadronic and radiative $D^*$ decays

abstract:
  A recent measurement of the total $D^{*+}$ width, $\Gamma_{\rm tot}(D^{*+}) =
(83.3 \pm 1.3 \pm 1.4)$ keV, is shown to be close to earlier predictions based
on the single-quark-transition hypothesis. Those predictions are updated using
more recent masses and branching fractions to a value of 80.4 keV, with a small
uncertainty associated with the radiative branching fractions of $D^{*0}$ and
$D^{*+}$. A prediction for the total width of $D_2(2460)$ and its partial width
into $D^* \pi$ and $D \pi$ is also updated, and found to be in agreement with
experiment.


title: 4-Spinors and 5D Spacetime

abstract:
  We revisit the subject exploring maps from the space of 4-spinors to 3+1
space-time that commute with the Lorentz transformation. All known mappings
have a natural embedding in a higher five dimensional spacetime, and can be
succinctly expressed as products of quaternions, or split-quaternions,
depending on the signature of the embedding 5D spacetime. It is in this sense
that we may view the geometry of 4-spinors as being related to the `square
root' of five dimensional spacetime. In particular, a point in 5D spacetime may
be identified with a corresponding 4-spinor that is uniquely determined up to a
quaternionic - or split-quaternionic - phase.


title:
A new limit on local Lorentz invariance violation of gravity from
  solitary pulsars

abstract:
  Gravitational preferred frame effects are generally predicted by alternative
theories that exhibit an isotropic violation of local Lorentz invariance of
gravity. They are described by three parameters in the parametrized
post-Newtonian formalism. One of their strong-field generalizations, $\hat
\alpha_2$, induces a precession of a pulsar's spin around its movement
direction with respect to the preferred frame. We constrain $\hat \alpha_2$ by
using the non-detection of such a precession using the characteristics of the
pulse profile. In our analysis we use a large number of observations from the
100-m Effelsberg radio telescope, which cover a time span of approximately 15
years. By combining data from two solitary millisecond pulsars, PSRs B1937+21
and J1744-1134, we get a limit of $|\hat \alpha_2| < 1.6 \times 10^{-9}$ at 95%
confidence level, which is more than two orders of magnitude better than its
best weak-field counterpart from the Solar system.


title:
CoRoT 102749568: mode identification in a delta Scuti star based on
  regular spacings

abstract:
  The high accuracy of space data increased the number of the periodicities
determined for pulsating variable stars, but the mode identification is still a
critical point in the non-asymptotic regime. We use regularities in frequency
spacings for identifying the pulsation modes of the recently discovered delta
Sct star ID 102749568. In addition to analysing CoRoT light curves (15252
datapoints spanning 131 days), we obtained and analysed both spectroscopic and
extended multi-colour photometric data. We applied standard tools (MUFRAN,
Period04, SigSpec, and FAMIAS) for time-series analysis. A satisfactory
light-curve fit was obtaining by means of 52 independent modes and 15
combination terms. The frequency spacing revealed distinct peaks around large
(25.55-31.43 microHz), intermediate (9.80, 7.66 microHz), and low (2.35
microHz) separations. We directly identified 9 modes, and the l and n values of
other three modes were extrapolated. The combined application of spectroscopy,
multi-colour photometry, and modelling yielded the precise physical parameters
and confirmed the observational mode identification. The large separation
constrained the log g and related quantities. The dominant mode is the radial
first overtone.


title:
Les index pour les entrep\^ots de donn\'ees : comparaison entre index
  arbre-B et Bitmap

abstract:
  With the development of decision systems and specially data warehouses, the
visibility of the data warehouse design before its creation has become
essential, and that because of data warehouse importance as considered as the
unique data source giving meaning to the decision. In a decision system the
proper functioning of a data warehouse resides in the smooth running of the
middleware tools ETC step one hand, and the restitution step through the data
mining, reporting solutions, dashboards... etc other. The large volume of data
that passes through these stages require an optimal design for a highly
efficient decision system, without disregarding the choice of technologies that
are introduced for the data warehouse implementation such as: database
management system, the type of server operating systems, physical server
architecture (64-bit, for example) that can be a benefit performance of this
system. The designer of the data warehouse should consider the effectiveness of
data query, this depends on the selection of relevant indexes and their
combination with the materialized views, note that the index selection is a
NPcomplete problem, because the number of indexes is exponential in the total
number of attributes in the database, So, it is necessary to provide, while the
data warehouse design, the suitable type of index for this data warehouse. This
paper presents a comparative study between the index B-tree type and type
Bitmap, their advantages and disadvantages, with a real experiment showing that
its index of type Bitmap more advantageous than the index B-tree type.


title:
MacWilliams Type identities for $m$-spotty Rosenbloom-Tsfasman weight
  enumerators over finite commutative Frobenius rings

abstract:
  The $m$-spotty byte error control codes provide a good source for detecting
and correcting errors in semiconductor memory systems using high density RAM
chips with wide I/O data (e.g. 8, 16, or 32 bits). $m$-spotty byte error
control codes are very suitable for burst correction. M. \"{O}zen and V. Siap
[7] proved a MacWilliams identity for the $m$-spotty Rosenbloom-Tsfasman
(shortly RT) weight enumerators of binary codes. The main purpose of this paper
is to present the MacWilliams type identities for $m$-spotty RT weight
enumerators of linear codes over finite commutative Frobenius rings.


title: Overconvergent cohomology and quaternionic Darmon points

abstract:
  We develop the (co)homological tools that make effective the construction of
the quaternionic Darmon points introduced by Matthew Greenberg. In addition, we
use the overconvergent cohomology techniques of Pollack--Pollack to allow for
the efficient calculation of such points. Finally, we provide the first
numerical evidence supporting the conjectures on their rationality.


title: Branching Law for the Finite Subgroups of SL(4,C)

abstract:
  In the framework of McKay correspondence we determine, for every finite
subgroup $\Gamma$ of $\mathbf{SL}_4\mathbb{C}$, how the finite dimensional
irreducible representations of $\mathbf{SL}_4\mathbb{C}$ decompose under the
action of $\Gamma$. Let $\go{h}$ be a Cartan subalgebra of
$\go{sl}_4\mathbb{C}$ and let $\varpi_1,\,\varpi_2,\,\varpi_3$ be the
corresponding fundamental weights. For $(p,q,r)\in \mathbb{N}^3$, the
restriction $\pi_{p,q,r}|_\Gamma$ of the irreducible representation
$\pi_{p,q,r}$ of highest weight $p\varpi_1+q\varpi_2+r\varpi_3$ of
$\mathbf{SL}_4\mathbb{C}$ decomposes as
${\pi_{p,q,r}}|_{\Gamma}=\bigoplus_{i=0}^l m_i(p,q,r)\gamma_i.$ We determine
the multiplicities $m_i(p,q,r)$ and prove that the series
$P_\Gamma(t,u,w)_i=\sum_{p=0}^\infty\sum_{q=0}^\infty\sum_{r=0}^\infty
m_i(p,q,r)t^pu^qw^r$ are rational functions. This generalizes results from
Kostant for $\mathbf{SL}_2\mathbb{C}$ and our preceding works about
$\mathbf{SL}_3\mathbb{C}$.


title:
Protected state enhanced quantum metrology with interacting two-level
  ensembles

abstract:
  Ramsey interferometry is routinely used in quantum metrology for the most
sensitive measurements of optical clock frequencies. Spontaneous decay to the
electromagnetic vacuum ultimately limits the interrogation time and thus sets a
lower bound to the optimal frequency sensitivity. In dense ensembles of
two-level systems the presence of collective effects such as superradiance and
dipole-dipole interaction tends to decrease the sensitivity even further. We
show that by a redesign of the Ramsey-pulse sequence to include different
rotations of individual spins that effectively fold the collective state onto a
state close to the center of the Bloch sphere, partial protection from
collective decoherence and dephasing is possible. This allows a significant
improvement in the sensitivity limit of a clock transition detection scheme
over the conventional Ramsey method for interacting systems and even for
non-interacting decaying atoms.


title: General Drift Analysis with Tail Bounds

abstract:
  Drift analysis is one of the state-of-the-art techniques for the runtime
analysis of randomized search heuristics (RSHs) such as evolutionary algorithms
(EAs), simulated annealing etc. The vast majority of existing drift theorems
yield bounds on the expected value of the hitting time for a target state,
e.g., the set of optimal solutions, without making additional statements on the
distribution of this time. We address this lack by providing a general drift
theorem that includes bounds on the upper and lower tail of the hitting time
distribution. The new tail bounds are applied to prove very precise
sharp-concentration results on the running time of a simple EA on standard
benchmark problems, including the class of general linear functions.
Surprisingly, the probability of deviating by an $r$-factor in lower order
terms of the expected time decreases exponentially with $r$ on all these
problems. The usefulness of the theorem outside the theory of RSHs is
demonstrated by deriving tail bounds on the number of cycles in random
permutations. All these results handle a position-dependent (variable) drift
that was not covered by previous drift theorems with tail bounds. Moreover, our
theorem can be specialized into virtually all existing drift theorems with
drift towards the target from the literature. Finally, user-friendly
specializations of the general drift theorem are given.


title:
Exploiting Data Parallelism in the yConvex Hypergraph Algorithm for
  Image Representation using GPGPUs

abstract:
  To define and identify a region-of-interest (ROI) in a digital image, the
shape descriptor of the ROI has to be described in terms of its boundary
characteristics. To address the generic issues of contour tracking, the yConvex
Hypergraph (yCHG) model was proposed by Kanna et al [1]. In this work, we
propose a parallel approach to implement the yCHG model by exploiting massively
parallel cores of NVIDIA's Compute Unified Device Architecture (CUDA). We
perform our experiments on the MODIS satellite image database by NASA, and
based on our analysis we observe that the performance of the serial
implementation is better on smaller images, but once the threshold is achieved
in terms of image resolution, the parallel implementation outperforms its
sequential counterpart by 2 to 10 times (2x-10x). We also conclude that an
increase in the number of hyperedges in the ROI of a given size does not impact
the performance of the overall algorithm.


title: The cosmic-ray positron excess from a local Dark Matter over-density

abstract:
  We show that the cosmic-ray positron excess measured by PAMELA and AMS could
be induced by Dark Matter annihilations in a local over-density. In such a
context leptophilic DM is not needed and good fits to positron data, in
agreement with antiproton and gamma-ray measurements, are obtained for DM
annihilations to $WW$, $hh$, $ZZ$, $ t \bar t$, $b \bar b$, $q\bar q$ channels.
The classic Dark Matter candidates, such as the pure supersymmetric Wino with
standard thermal annihilation cross-section, can fit the positron excess,
without invoking any additional assumption on Dark Matter properties.


title:
Valuation Perspectives and Decompositions for Variable Annuities with
  GMWB riders

abstract:
  The guaranteed minimum withdrawal benefit (GMWB) rider, as an add on to a
variable annuity (VA), guarantees the return of premiums in the form of peri-
odic withdrawals while allowing policyholders to participate fully in any
market gains. GMWB riders represent an embedded option on the account value
with a fee structure that is different from typical financial derivatives. We
consider fair pricing of the GMWB rider from a financial economic perspective.
Particular focus is placed on the distinct perspectives of the insurer and
policyholder and the unifying relationship. We extend a decomposition of the VA
contract into components that reflect term-certain payments and embedded
derivatives to the case where the policyholder has the option to surrender, or
lapse, the contract early.


title: Artifact-free data recovery system for an ASNOM application

abstract:
  A digital signal acquisition system for an Apertureless SNOM (ASNOM) based on
a digital signal processing (DSP) card is presented. An electromagnetic wave
scattered by an AFM-like tip is initially detected by an optical homodyning in
a Michelson interferometer, with a homodyne phase modulation caused by a
periodic travel of the reference arm mirror. Utilizing a non-linear dependency
of the tip scattering amplitude on a tip-sample separation distance, the
non-fundamental components of a tip oscillation frequency are recovered in
optical signal within each tip oscillation period. A detected value,
corresponding mostly to the near-field modes of a tip-sample electromagnetic
interaction, is then averaged over all reference phases. A modular structure of
the data acquisition and signal recovery program allows modify easily the modes
of operation and the recovery algorithms.


title: Coupling structure of multi-field primordial perturbations

abstract:
  We investigate the coupling relations among perturbations in general
multi-field models. We derived the equations of motion for both background and
perturbations in a general basis. Within this formalism, we revisit the
construction of kinematic orthogonal normal vectors using the successive time
derivatives of the background field velocity. We show that the coupling
relations among modes in this kinematic basis can be reduced, by employing the
background equations of motion for the scalar fields and their high order time
derivatives. There are two typical features in the field space: inflationary
trajectory and geometry of the potential. Correspondingly, the couplings among
modes fall into two categories: one is controlled only by the kinematic
quantities, the other involves high order derivatives of the potential.
Remarkably, the couplings of the first category, i.e. controlled by the
kinematic quantities only, show a "chain" structure. That is, each mode is only
coupled to its two neighbour modes.


title:
Small hydrocarbon molecules in cloud-forming Brown Dwarf and giant gas
  planet atmospheres

abstract:
  We study the abundances of complex carbon-bearing molecules in the
oxygen-rich dust- forming atmospheres of Brown Dwarfs and giant gas planets.
The inner atmospheric re- gions that form the inner boundary for thermochemical
gas-phase models are investigated. Results from Drift-phoenix atmosphere
simulations, which include the feedback of phase- non-equilibrium dust cloud
formation on the atmospheric structure and the gas-phase abun- dances, are
utilised. The resulting element depletion leads to a shift in the
carbon-to-oxygen ratio such that several hydrocarbon molecules and
cyanopolycyanopolyynene molecules can be present. An increase in surface
gravity and/or a decrease in metallicity support the increase in the partial
pressures of these species. CO, CO2, CH4, and HCN contain the largest fraction
of carbon. In the upper atmosphere of low-metallicity objects, more carbon is
contained in C4H than in CO, and also CH3 and C2H2 play an increasingly
important role as carbon-sink. We determine chemical relaxation time-scales to
evaluate if hydrocarbon molecules can be affected by transport-induced
quenching. Our results suggest that a considerable amount of C2H6 and C2H2
could be expected in the upper atmospheres not only of giant gas planets, but
also of Brown Dwarfs. However, the exact quenching height strongly depends on
the data source used. These results will have an impact on future
thermo-kinetic studies, as they change the inner boundary condition for those
simulations.


title: The Effect of Weak Lensing on Distance Estimates from Supernovae

abstract:
  Using a sample of 608 Type Ia supernovae from the SDSS-II and BOSS surveys,
combined with a sample of foreground galaxies from SDSS-II, we estimate the
weak lensing convergence for each supernova line-of-sight. We find that the
correlation between this measurement and the Hubble residuals is consistent
with the prediction from lensing (at a significance of 1.7sigma. Strong
correlations are also found between the residuals and supernova nuisance
parameters after a linear correction is applied. When these other correlations
are taken into account, the lensing signal is detected at 1.4sigma. We show for
the first time that distance estimates from supernovae can be improved when
lensing is incorporated by including a new parameter in the SALT2 methodology
for determining distance moduli. The recovered value of the new parameter is
consistent with the lensing prediction. Using CMB data from WMAP7, H0 data from
HST and SDSS BAO measurements, we find the best-fit value of the new lensing
parameter and show that the central values and uncertainties on Omega_m and w
are unaffected. The lensing of supernovae, while only seen at marginal
significance in this low redshift sample, will be of vital importance for the
next generation of surveys, such as DES and LSST, which will be systematics
dominated.


title: Areas of spherical and hyperbolic triangles in terms of their midpoints

abstract:
  Let $M$ be either the 2-sphere $\SS^2 \subset\RR^3$ or the hyperbolic plane
$\HH^2 \subset \RR^3$. If $\Delta(abc)$ is a geodesic triangle on $M$ with
corners at $a,b,c\in M$, we denote by $\alpha, \beta, \gamma\in M$ the
midpoints of their sides. If $\Omega$ denotes the oriented area of this
triangle on $M$, it satisfies the relations:
  $$ \sin(\Omega/2) = \frac{\Det_3(abc)}{\sqrt{2(1 + \scalar{a}b)(1 +
\scalar{b}c)(1 + \scalar{c}a)}} = \Det_3(\alpha\beta\gamma) \, $$ where
$\scalar{\}{\}$ denotes the Euclidean scalar product for $M=\SS^2$ and the
Lorentzian scalar product for $M=\HH^2$. On the hyperbolic plane one should
always take the solution with $\modu{\Omega/2}<\pi/2$. On the sphere, singular
cases excepted, a straightforward procedure tells us which solution of this
equation is the correct one.


title: The Sound Edge of the Quenching Jets

abstract:
  When quenching jets deposit certain amount of energy and momentum into
ambient matter, part of it propagates in the form of shocks/sounds. The "sound
surface", separating disturbed and undisturbed parts of the fireball, makes
what we call the sound edge of jets. In this work we semi-analytically study
its shape, in various geometries. We further argue that since hadrons with in
the kinematical range of $p_\perp\sim 2\, GeV$ originate mostly from the "rim"
of the fireball, near the maximum of the radial flow at the freezeout surface,
only the intersection of the "sound surface" with this "rim" would be
observable. The resulting "jet edge" has a form of extra matter at the elliptic
curve, in $\Delta \phi, \Delta \eta$ coordinates, with radius $|\Delta \phi|
\sim |\Delta \eta |\sim 1$. In the case of large energy/momentum deposition
$\sim 100 \, GeV$ we argue that the event should be considered as two
sub-events, with interior of the "sound surface" having modified radial and
directed flow. We further argue that in the kinematical range of $p_\perp\sim
3\, GeV$ the effect of that can be large enough to be seen on event-by-event
basis. If so, this effect has a potential to become a valuable tool to address
geometry of jet production and quenching.


title:
Mechanism design for resource allocation in networks with intergroup
  competition and intragroup sharing

abstract:
  We consider a network where strategic agents, who are contesting for
allocation of resources, are divided into fixed groups. The network control
protocol is such that within each group agents get to share the resource and
across groups they contest for it. A prototypical example is the allocation of
data rate on a network with multicast/multirate architecture. Compared to the
unicast architecture (which is a special case), the multicast/multirate
architecture can result in substantial bandwidth savings. However, design of a
market mechanism in such a scenario requires dealing with both private and
public good problems as opposed to just private goods in unicast.
  The mechanism proposed in this work ensures that social welfare maximizing
allocation on such a network is realized at all Nash equilibria (NE) i.e., full
implementation in NE. In addition it is individually rational, i.e., agents
have an incentive to participate in the mechanism. The mechanism, which is
constructed in a quasi-systematic way starting from the dual of the centralized
problem, has a number of useful properties. Specifically, due to a novel
allocation scheme, namely "radial projection", the proposed mechanism results
in feasible allocation even off equilibrium. This is a practical necessity for
any realistic mechanism since agents have to "learn" the NE through a dynamic
process. Finally, it is shown how strong budget balance at equilibrium can be
achieved with a minimal increase in message space as an add-on to a weakly
budget balanced mechanism.


title: Priced Timed Petri Nets

abstract:
  We consider priced timed Petri nets, i.e., unbounded Petri nets where each
token carries a real-valued clock. Transition arcs are labeled with time
intervals, which specify constraints on the ages of tokens. Furthermore, our
cost model assigns token storage costs per time unit to places, and firing
costs to transitions. This general model strictly subsumes both priced timed
automata and unbounded priced Petri nets. We study the cost of computations
that reach a given control-state. In general, a computation with minimal cost
may not exist, due to strict inequalities in the time constraints. However, we
show that the infimum of the costs to reach a given control-state is computable
in the case where all place and transition costs are non-negative. On the other
hand, if negative costs are allowed, then the question whether a given
control-state is reachable with zero overall cost becomes undecidable. In fact,
this negative result holds even in the simpler case of discrete time (i.e.,
integer-valued clocks).


title: Cosmology with Void-Galaxy Correlations

abstract:
  Galaxy bias, the unknown relationship between the clustering of galaxies and
the underlying dark matter density field is a major hurdle for cosmological
inference from large-scale structure. While traditional analyses focus on the
absolute clustering amplitude of high-density regions mapped out by galaxy
surveys, we propose a relative measurement that compares those to the
underdense regions, cosmic voids. On the basis of realistic mock catalogs we
demonstrate that cross correlating galaxies and voids opens up the possibility
to calibrate galaxy bias and to define a static ruler thanks to the observable
geometric nature of voids. We illustrate how the clustering of voids is related
to mass compensation and show that volume-exclusion significantly reduces the
degree of stochasticity in their spatial distribution. Extracting the
spherically averaged distribution of galaxies inside voids from their cross
correlations reveals a remarkable concordance with the mass-density profile of
voids.


title: The holographic dilaton

abstract:
  We study a set of examples of holographic duals to theories with spontaneous
breaking of conformal invariance in different dimensions. The geometries are
domain walls interpolating between two AdS spaces, with a non-trivial
background scalar field dual to a relevant operator. We comment on a subtlety
in the low momentum expansion pointed out in arXiv:1304.3051 for the case of
background gravity and revise the dynamical gravity results of arXiv:1207.0006,
where the dilaton pole was missing in the scalar-scalar and tensor-tensor
two-point functions. We compute the energy-momentum tensor and scalar two-point
functions and show that there is indeed a massless dilaton pole.


title: Simulating intergalactic quasar scintillation

abstract:
  Intergalactic scintillation of distant quasars is sensitive to free electrons
and therefore complements Ly$\alpha$ absorption line experiments probing the
neutral intergalactic medium (IGM). We present a new scheme to compute IGM
refractive scintillation effects on distant sources in combination with
Adaptive Mesh Refinement cosmological simulations. First we validate our model
by reproducing the well-known interstellar scintillation (ISS) of Galactic
sources. The simulated cosmic density field is then used to infer the
statistical properties of intergalactic scintillation. Contrary to previous
claims, we find that the scattering measure of the simulated IGM at $z<2$ is
$\langle \mbox{SM}_{\equ}\rangle=3.879$, i.e. almost 40 times larger than for
the usually assumed smooth IGM. This yield an average modulation index ranging
from 0.01 ($\nu_s=5$ GHz) up to 0.2 ($\nu_s=50$ GHz); above $\nu_{s}\gsim30$
GHz the IGM contribution dominates over ISS modulation. We compare our model
with data from a $0.3\leq z\leq 2$ quasar sample observed at $\nu_{\obs}=8.4$
GHz. For this high frequency ($10.92\leq \nu_s \leq 25.2$), high galactic
latitude sample ISS is negligible, and IGM scintillation can reproduce the
observed modulation with a 4% accuracy, without invoking intrinsic source
variability. We conclude by discussing the possibility of using IGM
scintillation as a tool to pinpoint the presence of intervening high-$z$
groups/clusters along the line of sight, thus making it a probe suitably
complementing Sunyaev-Zeldovich data recently obtained by \textit{Planck}.


title: Massive Graviton on a Spatial Condensate

abstract:
  In this paper, we consider the spatial gauge symmetries spontaneously break
down in GR, and graviton becomes massive on this spatial condensate background.
Such model can be considered as a simplest example of massive gravity. We then
apply our massive gravity theory to inflation, the graviton mass removes the IR
divergence of the inflationary loop diagram.


title: Recursive Stochastic Effects in Valley Hybrid Inflation

abstract:
  Hybrid Inflation is a two-field model where inflation ends by a tachyonic
instability, the duration of which is determined by stochastic effects and has
important observational implications. Making use of the recursive approach to
the stochastic formalism presented in Ref. [1], these effects are consistently
computed. Through an analysis of back-reaction, this method is shown to
converge in the valley but points toward an (expected) instability in the
waterfall. It is further shown that quasi-stationarity of the auxiliary field
distribution breaks down in the case of a short-lived waterfall. It is found
that the typical dispersion of the waterfall field at the critical point is
then diminished, thus increasing the duration of the waterfall phase and
jeopardizing the possibility of a short transition. Finally, it is found that
stochastic effects worsen the blue tilt of the curvature perturbations by an
order one factor when compared with the usual slow-roll contribution.


title:
Finalizing the proof of AGT relations with the help of the generalized
  Jack polynomials

abstract:
  Original proofs of the AGT relations with the help of the
Hubbard-Stratanovich duality of the modified Dotsenko-Fateev matrix model did
not work for beta different from one, because Nekrasov functions were not
properly reproduced by Selberg-Kadell integrals of Jack polynomials. We
demonstrate that if the generalized Jack polynomials, depending on the N-ples
of Young diagrams from the very beginning, are used instead of the N-linear
combinations of ordinary Jacks, this resolves the problem. Such polynomials
naturally arise as special elements in the equivariant cohomologies of the
GL(N)-instanton moduli spaces, and this also establishes connection to
alternative ABBFLT approach to the AGT relations, studying the action of chiral
algebras on the instanton moduli spaces. In this paper we describe a complete
proof of AGT in the simple case of GL(2) (N=2) Yang-Mills theory, i.e. the
4-point spherical conformal block of the Virasoro algebra.


title: Topological equivalence of crystal and quasicrystal band structures

abstract:
  A number of recent articles have reported the existence of topologically
non-trivial states and associated end states in one-dimensional incommensurate
lattice models that would usually only be expected in higher dimensions. Using
an explicit construction, we here argue that the end states have precisely the
same origin as their counterparts in commensurate models and that
incommensurability does not in fact provide a meaningful connection to the
topological classification of systems in higher dimensions. In particular, we
show that it is possible to smoothly interpolate between states with
commensurate and incommensurate modulation parameters without closing the band
gap and without states crossing the band gap.


title: Surface Defects and Resolvents

abstract:
  We study a large class of BPS surface defects in 4d N=2 gauge theories. They
are defined by coupling a 2d N=(2,2) gauged linear sigma model to the 4d bulk
degrees of freedom. Our main result is an efficient computation of the
effective twisted superpotential for all these models in terms of a basic
object closely related to the resolvent of the 4d gauge theory, which encodes
the curve describing the 4d low energy dynamics. We reproduce and extend the
results of brane constructions and compute the effective twisted superpotential
for general monodromy surface defects. We encounter novel, puzzling field
theory phenomena in the low energy dynamics of the simplest surface defects and
we propose some local models to explain them. We also study in some detail the
behavior of surface defects near monopole points of the bulk theory's Coulomb
branch. Finally, we explore the effect on the defect of breaking the bulk
supersymmetry from N=2 to N=1 and show that certain quantities are independent
of this breaking.


title: Tuned Models of Peer Assessment in MOOCs

abstract:
  In massive open online courses (MOOCs), peer grading serves as a critical
tool for scaling the grading of complex, open-ended assignments to courses with
tens or hundreds of thousands of students. But despite promising initial
trials, it does not always deliver accurate results compared to human experts.
In this paper, we develop algorithms for estimating and correcting for grader
biases and reliabilities, showing significant improvement in peer grading
accuracy on real data with 63,199 peer grades from Coursera's HCI course
offerings --- the largest peer grading networks analysed to date. We relate
grader biases and reliabilities to other student factors such as student
engagement, performance as well as commenting style. We also show that our
model can lead to more intelligent assignment of graders to gradees.


title:
Towards an Approach for Analysing the Strategic Alignment of Software
  Requirements using Quantified Goal Graphs

abstract:
  Analysing the strategic alignment of software requirements primarily provides
assurance to stakeholders that the software-to-be will add value to the
organisation. Additionally, such analysis can improve a requirement by
disambiguating its purpose and value, thereby supporting validation and
value-oriented decisions in requirements engineering processes, such as
prioritisation, release planning, and trade-off analysis. We review current
approaches that could enable such an analysis. We focus on Goal Oriented
Requirements Engineering methodologies, since goal graphs are well suited for
relating software goals to business goals. However, we argue that unless the
extent of goal-goal contribution is quantified with verifiable metrics, goal
graphs are not sufficient for demonstrating the strategic alignment of software
requirements. Since the concept of goal contribution is predictive, what
results is a forecast of the benefits of implementing software requirements.
Thus, we explore how the description of the contribution relationship can be
enriched with concepts such as uncertainty and confidence, non-linear
causation, and utility. We introduce the approach using an example software
project from Rolls-Royce.


title:
Controlling and Streaking Nanotip Photoemission by Enhanced Single-cycle
  Terahertz Pulses

abstract:
  The active control of matter by strong electromagnetic fields is of growing
importance, with applications all across the optical spectrum from the
extreme-ultraviolet to the far-infrared. In recent years, phase-stable
terahertz (THz) fields have shown tremendous potential in the observation and
manipulation of elementary excitations in complex systems. The combination of
concepts from attosecond science with advanced THz technology facilitates novel
spectroscopic schemes, such as THz streaking. In general, driving charges at
lower frequency enhances interaction energies and can promote drastically
different dynamics. For example, mid-infrared excitation induces field-driven
sub-cycle electron dynamics in nanostructure nearfields. Such frequency
scalings will also impact nanostructure-based streaking, which has been
theoretically proposed. Here, we experimentally demonstrate extensive control
over nanostructure photoelectron emission using single-cycle THz transients.
The locally enhanced THz near-field at a nanotip significantly amplifies or
suppresses the detected photocurrent. We present field-driven streaking
spectroscopy with spectral compression and expansion arising from electron
propagation within the nanolocalized volume. THz near-field streaking produces
rich spectrotemporal features and will yield unprecedented control over
ultrashort electron pulses for imaging and spectroscopy.


title: NECO - A scalable algorithm for NEtwork COntrol

abstract:
  We present an algorithm for the control of complex networks and other
nonlinear, high-dimensional dynamical systems. The computational approach is
based on the recently-introduced concept of compensatory perturbations --
intentional alterations to the state of a complex system that can drive it to a
desired target state even when there are constraints on the perturbations that
forbid reaching the target state directly. Included here is ready-to-use
software that can be applied to identify eligible control interventions in a
general system described by coupled ordinary differential equations, whose
specific form can be specified by the user. The algorithm is highly scalable,
with the computational cost scaling as the number of dynamical variables to the
power 2.5.

categories: math.OC cond-mat.dis-nn cs.DS nlin.AO physics.soc-ph


title:
On the nucleon paradigm: the nucleons are closer to reality than the
  protons and neutrons

abstract:
  There is a widespread delusion that in theoretical nuclear physics protons
and neutrons are the real thing, and nucleons are not more than a
mathematically equivalent formality. It is shown that, on the contrary,
nucleons are the real thing, because only a part of the theory is essentially
identical to proton-and-neutron theory, whereas the remaining part is
physically relevant. The approach is general. Thus, this is a paradigm of
relation of a wider and a more narrow theory, so that the wider theory
describes reality better. Also the relation of disjoint domains to the
exclusion principle is clarified. A general fermion theory of how to
distinguish identical particles is presented.


title:
Massive MIMO Systems with Non-Ideal Hardware: Energy Efficiency,
  Estimation, and Capacity Limits

abstract:
  The use of large-scale antenna arrays can bring substantial improvements in
energy and/or spectral efficiency to wireless systems due to the greatly
improved spatial resolution and array gain. Recent works in the field of
massive multiple-input multiple-output (MIMO) show that the user channels
decorrelate when the number of antennas at the base stations (BSs) increases,
thus strong signal gains are achievable with little inter-user interference.
Since these results rely on asymptotics, it is important to investigate whether
the conventional system models are reasonable in this asymptotic regime. This
paper considers a new system model that incorporates general transceiver
hardware impairments at both the BSs (equipped with large antenna arrays) and
the single-antenna user equipments (UEs). As opposed to the conventional case
of ideal hardware, we show that hardware impairments create finite ceilings on
the channel estimation accuracy and on the downlink/uplink capacity of each UE.
Surprisingly, the capacity is mainly limited by the hardware at the UE, while
the impact of impairments in the large-scale arrays vanishes asymptotically and
inter-user interference (in particular, pilot contamination) becomes
negligible. Furthermore, we prove that the huge degrees of freedom offered by
massive MIMO can be used to reduce the transmit power and/or to tolerate larger
hardware impairments, which allows for the use of inexpensive and
energy-efficient antenna elements.


title: Long-term Evolution of Photoevaporating Protoplanetary Disks

abstract:
  We perform calculations of our one-dimensional, two-zone disk model to study
the long-term evolution of the circumstellar disk. In particular, we adopt
published photoevaporation prescriptions and examine whether the
photoevaporative loss alone, coupled with a range of initial angular momenta of
the protostellar cloud, can explain the observed decline of the frequency of
optically-thick dusty disks with increasing age. In the parameter space we
explore, disks have accreting and/or non-accreting transitional phases lasting
of $\lesssim20 %$ of their lifetime, which is in reasonable agreement with
observed statistics. Assuming that photoevaporation controls disk clearing, we
find that initial angular momentum distribution of clouds needs to be weighted
in favor of slowly rotating protostellar cloud cores. Again, assuming inner
disk dispersal by photoevaporation, we conjecture that this skewed angular
momentum distribution is a result of fragmentation into binary or multiple
stellar systems in rapidly-rotating cores. Accreting and non-accreting
transitional disks show different evolutionary paths on the $\dot{M}-R_{\rm
wall}$ plane, which possibly explains the different observed properties between
the two populations. However, we further find that scaling the photoevaporation
rates downward by a factor of 10 makes it difficult to clear the disks on the
observed timescales, showing that the precise value of the photoevaporative
loss is crucial to setting the clearing times. While our results apply only to
pure photoevaporative loss (plus disk accretion), there may be implications for
models in which planets clear disks preferentially at radii of order 10 AU.


title: Synthesis, Crystal Structure and Physical Properties of Sr2FeOsO6

abstract:
  In the exploration of new osmium based double perovskites, Sr2FeOsO6 is a new
insertion in the existing family. The polycrystalline compound has been
prepared by solid state synthesis from the respective binary oxides. PXRD
analysis shows the structure is pseudo-cubic at room temperature, whereas
low-temperature synchrotron data refinements reveal the structure to be
tetragonal, space group I4/m. Heat capacity and magnetic measurements of
Sr2FeOsO6 indicated the presence of two magnetic phase transitions at T1 = 140
K and T2 = 67 K. Band structure calculations showed the compound as a narrow
energy gap semiconductor, which supports the experimental results obtained from
the resistivity measurements. The present study documents significant
structural and electronic effects of substituting Fe3+ for Cr3+ ion in
Sr2CrOsO6.


title:
Lattice Instability and Competing Spin Structures in the Double
  Perovskite Insulator Sr2FeOsO6

abstract:
  The semiconductor Sr2FeOsO6, depending on temperature, adopts two types of
spin structures that differ in the spin sequence of ferrimagnetic iron - osmium
layers along the tetragonal c-axis. Neutron powder diffraction experiments,
57Fe M\"ossbauer spectra, and density-functional theory calculations suggest
that this behavior arises because a lattice instability resulting in
alternating iron-osmium distances fine-tunes the balance of competing exchange
interactions. Thus, Sr2FeOsO6 is an example for a double perovskite, in which
the electronic phases are controlled by the interplay of spin, orbital, and
lattice degrees of freedom.


title: Protein Energy Landscapes Determined by 5-Dimensional Crystallography

abstract:
  Free energy landscapes decisively determine the progress of enzymatically
catalyzed reactions[1]. Time-resolved macromolecular crystallography unifies
transient-state kinetics with structure determination [2-4] because both can be
determined from the same set of X-ray data. We demonstrate here how barriers of
activation can be determined solely from five-dimensional crystallography [5].
Directly linking molecular structures with barriers of activation between them
allows for gaining insight into the structural nature of the barrier. We
analyze comprehensive time series of crystal-lographic data at 14 different
temperature settings and determine entropy and enthalpy contributions to the
barriers of activation. 100 years after the discovery of X-ray scattering, we
advance X-ray structure determination to a new frontier, the determination of
energy landscapes.


title: Vector triplets at the LHC

abstract:
  Several popular extensions of the Standard Model predict extra vector fields
that transform as triplets under the gauge group SU(2)_L. These multiplets
contain Z' and W' bosons, with masses and couplings related by gauge
invariance. We review some model-independent results about these new vector
bosons, with emphasis on di-lepton and lepton-plus-missing-energy signals at
the LHC.


title:
Global collapse of molecular clouds as a formation mechanism for the
  most massive stars

abstract:
  The relative importance of primordial molecular cloud fragmentation versus
large-scale accretion still remains to be assessed in the context of massive
core/star formation. Studying the kinematics of the dense gas surrounding
massive-star progenitors can tell us the extent to which large-scale flow of
material impacts the growth in mass of star-forming cores. Here we present a
comprehensive dataset of the 5500(+/-800) Msun infrared dark cloud
SDC335.579-0.272 (hereafter SDC335) which exhibits a network of cold, dense,
parsec-long filaments. Atacama Large Millimeter Array (ALMA) Cycle 0
observations reveal two massive star-forming cores, MM1 and MM2, sitting at the
centre of SDC335 where the filaments intersect. With a gas mass of
545(+770,-385) Msun contained within a source diameter of 0.05pc, MM1 is one of
the most massive, compact protostellar cores ever observed in the Galaxy. As a
whole, SDC335 could potentially form an OB cluster similar to the Trapezium
cluster in Orion. ALMA and Mopra single-dish observations of the SDC335 dense
gas furthermore reveal that the kinematics of this hub-filament system are
consistent with a global collapse of the cloud. These molecular-line data point
towards an infall velocity V_{inf} =0.7(+/-0.2) km/s, and a total mass infall
rate \dot{M}_{inf} = 2.5(+/-1.0) x 10^{-3} Msun/yr towards the central pc-size
region of SDC335. This infall rate brings 750(+/-300) Msun of gas to the centre
of the cloud per free-fall time (t_{ff}=3x10^5 yr). This is enough to double
the mass already present in the central pc-size region in 3.5(+2.2,-1.0) x
t_{ff}. These values suggest that the global collapse of SDC335 over the past
million year resulted in the formation of an early O-type star progenitor at
the centre of the cloud's gravitational potential well.


title:
Gluon Regge trajectory at two loops from Lipatov's high energy effective
  action

abstract:
  We present the derivation of the two-loop gluon Regge trajectory using
Lipatov's high energy effective action and a direct evaluation of Feynman
diagrams. Using a gauge invariant regularization of high energy divergences by
deforming the light-cone vectors of the effective action, we determine the
two-loop self-energy of the reggeized gluon, after computing the master
integrals involved using the Mellin-Barnes representations technique. The
self-energy is further matched to QCD through a recently proposed subtraction
prescription. The Regge trajectory of the gluon is then defined through
renormalization of the reggeized gluon propagator with respect to high energy
divergences. Our result is in agreement with previous computations in the
literature, providing a non-trivial test of the effective action and the
proposed subtraction and renormalization framework.


title: Magnetic order in Ce0.95Nd0.05CoIn5: the Q-phase at zero magnetic field

abstract:
  We report neutron scattering experiment results revealing the nature of the
magnetic order occurring in the heavy fermion superconductor Ce0.95Nd0.05CoIn5,
a case for which an antiferromagnetic state is stabilized at a temperature
below the superconducting transition one. We evidence an incommensurate order
and its propagation vector is found to be identical to that of the magnetic
field induced antiferromagnetic order occurring in the stoichiometric
superconductor CeCoIn5, the so-called Q-phase. The commonality between these
two cases suggests that superconductivity is a requirement for the formation of
this kind of magnetic order and the proposed mechanism is the enhancement of
nesting condition by d-wave order parameter with nodes in the nesting area.


title: Arithmetic quotients of the mapping class group

abstract:
  To every $Q$-irreducible representation $r$ of a finite group $H$, there
corresponds a simple factor $A$ of $Q[H]$ with an involution $\tau$. To this
pair $(A,\tau)$, we associate an arithmetic group $\Omega$ consisting of all
$(2g-2)\times (2g-2)$ matrices over a natural order of $A^{op}$ which preserve
a natural skew-Hermitian sesquilinear form on $A^{2g-2}$. We show that if $H$
is generated by less than $g$ elements, then $\Omega$ is a virtual quotient of
the mapping class group $Mod(\Sigma_g)$, i.e. a finite index subgroup of
$\Omega$ is a quotient of a finite index subgroup of $\Mod(\Sigma_g)$. This
shows that the mapping class group has a rich family of arithmetic quotients
(and "Torelli subgroups") for which the classical quotient $Sp(2g, Z)$ is just
a first case in a list, the case corresponding to the trivial group $H$ and the
trivial representation. Other pairs of $H$ and $r$ give rise to many new
arithmetic quotients of $Mod(\Sigma_g)$ which are defined over various
(subfields of) cyclotomic fields and are of type $Sp(2m), SO(2m,2m),$ and
$SU(m,m)$ for arbitrarily large $m$.


title: Microwave-activated conditional-phase gate for superconducting qubits

abstract:
  We introduce a new entangling gate between two fixed-frequency qubits
statically coupled via a microwave resonator bus which combines the following
desirable qualities: all-microwave control, appreciable qubit separation for
reduction of crosstalk and leakage errors, and the ability to function as a
two-qubit conditional-phase gate. A fixed, always-on interaction is explicitly
designed between higher energy (non-computational) states of two transmon
qubits, and then a conditional-phase gate is `activated' on the otherwise
unperturbed qubit subspace via a microwave drive. We implement this
microwave-activated conditional-phase gate with a fidelity from quantum process
tomography of 87%.


title: Crossed products of C*-algebras with the weak expectation property

abstract:
  If $\alpha$ is an amenable action of a discrete group $G$ on a unital
C*-algebra $A$, then the crossed-product C*-algebra $A\rtimes_\alpha G$ has the
weak expectation property if and only if $A$ has this property.


title:
Spin-noise correlations and spin-noise exchange driven by low-field
  spin-exchange collisions

abstract:
  The physics of spin exchange collisions have fueled several discoveries in
fundamental physics and numerous applications in medical imaging and nuclear
magnetic resonance. We here report on the experimental observation and
theoretical justification of spin-noise exchange, the transfer of spin-noise
from one atomic species to another. The signature of spin-noise exchange is an
increase of the total spin-noise power at low magnetic fields, on the order of
1 mG, where the two-species spin-noise resonances overlap. The underlying
physical mechanism is the two-species spin-noise correlation induced by
spin-exchange collisions.

categories: physics.atom-ph cond-mat.mes-hall math.PR quant-ph


title: Converting a real quantum bath to an effective classical noise

abstract:
  We present a cluster expansion method for approximating quantum spin-bath
dynamics in terms of a classical Gaussian stochastic process. The cluster
expansion produces the two-point correlation function of the approximate
classical bath, permitting rapid evaluation of noise-mitigating quantum control
strategies without resorting to computationally intensive dynamical decoupling
models. Our approximation is valid for the wide class of models possessing
negligible back-action and nearly-Gaussian noise. We study several instances of
the central spin decoherence problem in which the central spin and
randomly-located bath spins are alike and dipolarly coupled. For various pulse
sequences, we compare the coherence echo decay computed explicitly quantum
mechanically versus those computed using our approximate classical model, and
obtain agreement in most, but not all, cases. We demonstrate the utility of
these classical noise models by efficiently searching for the 4-pulse sequences
that maximally mitigate decoherence in each of these cases, a computationally
expensive task in the explicit quantum model.


title: Relative weak injectivity of operator system pairs

abstract:
  The concept of a relatively weakly injective pair of operator systems is
introduced and studied in this paper, motivated by relative weak injectivity in
the C*-algebra category. E. Kirchberg \cite{Kr} proved that the C*-algebra
$C^*(\mathbb{f}_\infty)$ of the free group $\mathbb{f}_\infty$ on countably
many generators characterizes relative weak injectivity for pairs of
C*-algebras by means of the maximal tensor product. One of the main results of
this paper shows that $C^*(\mathbb{f}_\infty)$ also characterises relative weak
injectivity in the operator system category. A key tool is the theory of
operator system tensor products \cite{KP1,KP2}.


title:
Compactly Supported Tensor Product Complex Tight Framelets with
  Directionality

abstract:
  Although tensor product real-valued wavelets have been successfully applied
to many high-dimensional problems, they can only capture well edge
singularities along the coordinate axis directions. As an alternative and
improvement of tensor product real-valued wavelets and dual tree complex
wavelet transform, recently tensor product complex tight framelets with
increasing directionality have been introduced in [8] and applied to image
denoising in [13]. Despite several desirable properties, the directional tensor
product complex tight framelets constructed in [8,13] are bandlimited and do
not have compact support in the space/time domain. Since compactly supported
wavelets and framelets are of great interest and importance in both theory and
application, it remains as an unsolved problem whether there exist compactly
supported tensor product complex tight framelets with directionality. In this
paper, we shall satisfactorily answer this question by proving a theoretical
result on directionality of tight framelets and by introducing an algorithm to
construct compactly supported complex tight framelets with directionality. Our
examples show that compactly supported complex tight framelets with
directionality can be easily derived from any given eligible low-pass filters
and refinable functions. Several examples of compactly supported tensor product
complex tight framelets with directionality have been presented.


title:
Insights on the astrophysics of supermassive black hole binaries from
  pulsar timing observations

abstract:
  Pulsar timing arrays (PTAs) are designed to detect the predicted
gravitational wave (GW) background produced by a cosmological population of
supermassive black hole (SMBH) binaries. In this contribution I review the
physics of such GW background, highlighting its dependence on the overall
binary population, the relation between SMBHs and their hosts, and their
coupling with the stellar and gaseous environment. The latter is particularly
relevant when it drives the binaries to extreme eccentricities (e>0.9), which
might be the case for stellar-driven systems. This causes a substantial
suppression of the low frequency signal, potentially posing a serious threat to
the effectiveness of PTA observations. A future PTA detection will allow to
directly observe for the first time subparsec SMBH binaries on their way to the
GW driven coalescence, providing important answers of the outstanding questions
related to the physics underlying the formation and evolution of these
spectacular sources.


title:
Dynamic Service Rate Control for a Single Server Queue with Markov
  Modulated Arrivals

abstract:
  We consider the problem of service rate control of a single server queueing
system with a finite-state Markov-modulated Poisson arrival process. We show
that the optimal service rate is non-decreasing in the number of customers in
the system; higher congestion rates warrant higher service rates. On the
contrary, however, we show that the optimal service rate is not necessarily
monotone in the current arrival rate. If the modulating process satisfies a
stochastic monotonicity property the monotonicity is recovered. We examine
several heuristics and show where heuristics are reasonable substitutes for the
optimal control. None of the heuristics perform well in all the regimes.
Secondly, we discuss when the Markov-modulated Poisson process with service
rate control can act as a heuristic itself to approximate the control of a
system with a periodic non-homogeneous Poisson arrival process. Not only is the
current model of interest in the control of Internet or mobile networks with
bursty traffic, but it is also useful in providing a tractable alternative for
the control of service centers with non-stationary arrival rates.


title: Spaser operation below threshold: autonomous vs. driven spasers

abstract:
  At the plasmon resonance, high Joule losses in a metal nanoparticle of a
spaser result in its low Q-factor. Due to the latter, to achieve the spasing
regime, in which the number of coherent plasmons exceeds the number of
incoherent plasmons, unsustainably high pump rates may be required. We show
that under the condition of loss compensation by a spaser driven by an external
optical wave, the number of coherent plasmons increases dramatically, and the
quantum noise is suppressed. Since the compensation of losses of the driving
wave may occur even near the spasing threshold, the number of coherent plasmons
may exceed the number of spontaneously excited plasmons at achievable pump
rates.


title:
Ontology Based Data Integration Over Document and Column Family Oriented
  NOSQL

abstract:
  The World Wide Web infrastructure together with its more than 2 billion users
enables to store information at a rate that has never been achieved before.
This is mainly due to the will of storing almost all end-user interactions
performed on some web applications. In order to reply to scalability and
availability constraints, many web companies involved in this process recently
started to design their own data management systems. Many of them are referred
to as NOSQL databases, standing for 'Not only SQL'. With their wide adoption
emerges new needs and data integration is one of them. In this paper, we
consider that an ontology-based representation of the information stored in a
set of NOSQL sources is highly needed. The main motivation of this approach is
the ability to reason on elements of the ontology and to retrieve information
in an efficient and distributed manner. Our contributions are the following:
(1) we analyze a set of schemaless NOSQL databases to generate local
ontologies, (2) we generate a global ontology based on the discovery of
correspondences between the local ontologies and finally (3) we propose a query
translation solution from SPARQL to query languages of the sources. We are
currently implementing our data integration solution on two popular NOSQL
databases: MongoDB as a document database and Cassandra as a column family
store.


title:
The closed graph function from plane with the network of discontinuity
  points

abstract:
  The main result of this paper states, that if a function $f:\R^2\to [0,
+\infty)$ has a closed graph and the set of discontinuity points is a network
(as defined by Kuratowski in Topology II, 61.IV), then the graph of $f$ is
disconnected. It is also proven that this result can be easily generalised to a
function $f:\R^2\to Y$ where $Y$ is a $\sigma$-locally compact metrisable
space.


title: Twisting of paramodular vectors

abstract:
  Let $F$ be a non-archimedean local field of characteristic zero, let
$(\pi,V)$ be an irreducible, admissible representation of $\GSp(4,F)$ with
trivial central character, and let $\chi$ be a quadratic character of
$F^\times$ with conductor $c(\chi)>1$. We define a twisting operator $T_\chi$
from paramodular vectors for $\pi$ of level $n$ to paramodular vectors for
$\chi \otimes \pi$ of level $\max(n+2c(\chi),4c(\chi))$, and prove that this
operator has properties analogous to the well-known $\GL(2)$ twisting operator.


title: Top Quark as a Dark Portal and Neutrino Mass Generation

abstract:
  We present a new model for radiatively generating Majorana active neutrino
masses while incorporating a viable dark matter candidate. This is possible by
extending the Standard Model with a single Majorana neutrino endowed with a
dark parity, a colour electroweak singlet scalar, as well as a colour
electroweak triplet scalar. Within this framework, the $up$-type quarks play a
special role, serving as a portal for dark matter, and a messenger for neutrino
mass generation. We consider three benchmark scenarios where the abundance of
dark matter can match the latest experimental results, while generating
neutrino masses in the milli-electronvolt range. We show how constraints from
lepton flavour violation, in particular the branching fraction of $\mu\to
e\gamma$, can place lower bounds on the coupling between our dark matter
candidate and top quarks. Furthermore, we show that this coupling can also be
constrained using collider data from the Tevatron and the LHC.


title:
The local equivariant Tamagawa number conjecture for almost abelian
  extensions

abstract:
  We prove the local equivariant Tamagawa number conjecture for the motive of
an abelian extension of an imaginary quadratic field with the action of the
Galois group ring for all split primes p not equal to 2 or 3 at all negative
integer values s.


title: Polynomial-time perfect matchings in dense hypergraphs

abstract:
  Let $H$ be a $k$-graph on $n$ vertices, with minimum codegree at least $n/k +
cn$ for some fixed $c > 0$. In this paper we construct a polynomial-time
algorithm which finds either a perfect matching in $H$ or a certificate that
none exists. This essentially solves a problem of Karpi\'nski, Ruci\'nski and
Szyma\'nska; Szyma\'nska previously showed that this problem is NP-hard for a
minimum codegree of $n/k - cn$. Our algorithm relies on a theoretical result of
independent interest, in which we characterise any such hypergraph with no
perfect matching using a family of lattice-based constructions.


title: Quantum Mechanical Effects from Deformation Theory

abstract:
  We consider deformations of quantum mechanical operators by using the novel
construction of warped convolutions. The deformation enables us to obtain
several quantum mechanical effects where electromagnetic and gravitomagnetic
fields play a role. Furthermore, a quantum plane can be defined by using the
deformation techniques. This in turn gives an experimentally verifiable effect.


title: Pulse shape discrimination for GERDA Phase I data

abstract:
  The GERDA experiment located at the LNGS searches for neutrinoless double
beta (0\nu\beta\beta) decay of ^{76}Ge using germanium diodes as source and
detector. In Phase I of the experiment eight semi-coaxial and five BEGe type
detectors have been deployed. The latter type is used in this field of research
for the first time. All detectors are made from material with enriched ^{76}Ge
fraction. The experimental sensitivity can be improved by analyzing the pulse
shape of the detector signals with the aim to reject background events. This
paper documents the algorithms developed before the data of Phase I were
unblinded. The double escape peak (DEP) and Compton edge events of 2.615 MeV
\gamma\ rays from ^{208}Tl decays as well as 2\nu\beta\beta\ decays of ^{76}Ge
are used as proxies for 0\nu\beta\beta\ decay. For BEGe detectors the chosen
selection is based on a single pulse shape parameter. It accepts 0.92$\pm$0.02
of signal-like events while about 80% of the background events at
Q_{\beta\beta}=2039 keV are rejected.
  For semi-coaxial detectors three analyses are developed. The one based on an
artificial neural network is used for the search of 0\nu\beta\beta\ decay. It
retains 90% of DEP events and rejects about half of the events around
Q_{\beta\beta}. The 2\nu\beta\beta\ events have an efficiency of 0.85\pm0.02
and the one for 0\nu\beta\beta\ decays is estimated to be 0.90^{+0.05}_{-0.09}.
A second analysis uses a likelihood approach trained on Compton edge events.
The third approach uses two pulse shape parameters. The latter two methods
confirm the classification of the neural network since about 90% of the data
events rejected by the neural network are also removed by both of them. In
general, the selection efficiency extracted from DEP events agrees well with
those determined from Compton edge events or from 2\nu\beta\beta\ decays.


title:
Controlling the Precision-Recall Tradeoff in Differential Dependency
  Network Analysis

abstract:
  Graphical models have gained a lot of attention recently as a tool for
learning and representing dependencies among variables in multivariate data.
Often, domain scientists are looking specifically for differences among the
dependency networks of different conditions or populations (e.g. differences
between regulatory networks of different species, or differences between
dependency networks of diseased versus healthy populations). The standard
method for finding these differences is to learn the dependency networks for
each condition independently and compare them. We show that this approach is
prone to high false discovery rates (low precision) that can render the
analysis useless. We then show that by imposing a bias towards learning similar
dependency networks for each condition the false discovery rates can be reduced
to acceptable levels, at the cost of finding a reduced number of differences.
Algorithms developed in the transfer learning literature can be used to vary
the strength of the imposed similarity bias and provide a natural mechanism to
smoothly adjust this differential precision-recall tradeoff to cater to the
requirements of the analysis conducted. We present real case studies
(oncological and neurological) where domain experts use the proposed technique
to extract useful differential networks that shed light on the biological
processes involved in cancer and brain function.


title: Constructions and Cohomology of color Hom-Lie algebras

abstract:
  The main purpose of this paper is to define representations and a cohomology
of color Hom-Lie algebras and to study some key constructions and properties.
We describe Hartwig-Larsson-Silvestrov Theorem in the case of $\Gamma$-graded
algebras, study one-parameter formal deformations, discuss
$\alpha^{k}$-generalized derivation and provide examples.


title:
Few-body semiclassical approach to nucleon transfer and emission
  reactions

abstract:
  A three-body semiclassical model is proposed to describe the nucleon transfer
and emission reactions in a heavy-ion collision. In this model the two heavy
particles, i.e. nuclear cores A$_1(Z_{A_1}, M_{A_1})$ and A$_2(Z_{A_2},
M_{A_2})$, move along classical trajectories $\vec R_1(t)$ and $\vec R_2(t)$
respectively, while the dynamics of the lighter neutron, n, is considered from
a quantum mechanical point of view. Here, $M_i$ are the nucleon masses and
$Z_i$ are the Coulomb charges of the heavy nuclei ($i=1,2$). A Faddeev-type
semiclassical formulation using realistic paired nuclear-nuclear potentials is
applied so that all three channels (elastic, rearrangement and break-up) are
described in an unified manner. In order to solve these time-dependent
equations the Faddeev components of the total three-body wave-function are
expanded in terms of the input and output channel target eigenfunctions. In the
special case when the nuclear cores are identical (A$_1 \equiv$ A$_2$) and the
two-level approximation in the expansion over target functions the
time-dependent semiclassical Faddeev equations are resolved in an explicit way.
To determine the realistic $\vec R_1(t)$ and $\vec R_2(t)$ trajectories of the
nuclear cores a self-consistent approach based on the Feynman path integral
theory is applied.


title: Optimality in multiple comparison procedures

abstract:
  When many (m) null hypotheses are tested with a single dataset, the control
of the number of false rejections is often the principal consideration. Two
popular controlling rates are the probability of making at least one false
discovery (FWER) and the expected fraction of false discoveries among all
rejections (FDR). Scaled multiple comparison error rates form a new family that
bridges the gap between these two extremes. For example, the Scaled Expected
Value (SEV) limits the number of false positives relative to an arbitrary
increasing function of the number of rejections, that is, E(FP/s(R)). We
discuss the problem of how to choose in practice which procedure to use, with
elements of an optimality theory, by considering the number of false rejections
FP separately from the number of correct rejections TP. Using this framework we
will show how to choose an element in the new family mentioned above.


title:
Bi-Directional Energy Cascades and the Origin of Kinetic Alfv\'enic and
  Whistler Turbulence in the Solar Wind

abstract:
  The observed sub-proton scale turbulence spectrum in the solar wind raises
the question of how that turbulence originates. Observations of keV energetic
electrons during solar quite-time suggest them as possible source of free
energy to drive the turbulence. Using particle-in-cell simulations, we explore
how free energy in energetic electrons, released by an electron two-stream
instability drives Weibel-like electromagnetic waves that excite wave-wave
interactions. Consequently, both kinetic Alfv\'enic and whistler waves are
excited that evolve through inverse and forward magnetic energy cascades.


title:
Nonequilibrium Green's function theory for predicting device-to-device
  variability

abstract:
  Due to random dopant fluctuations, the device-to-device variability is a
serious challenge to emerging nanoelectronics. In this work we present
theoretical formalisms and numerical simulations of quantum transport
variability, based on the nonequilibrium Green's functions and the multiple
scattering theory. We have developed a general formalism using the diagrammatic
technique within the coherent potential approximation (CPA) that can be applied
to a wide range of disorder concentrations. In addition, we have developed a
method by using a perturbative expansion within the low concentration
approximation (LCA) that is extremely useful for typical nanoelectronic devices
having low dopant concentration. Applying both formalisms, transport
fluctuations due to random impurities can be predicted without lengthy brute
force computation of ensemble of devices structures. Numerical implementations
of the formalisms are demonstrated using both tight-binding models and first
principles models.


title: Degeneration of the Julia set to singular loci of algebraic curves

abstract:
  We show that, when a non-integrable rational map changes to an integrable one
continuously, a large part of the Julia set of the map approach indeterminate
points (IDP) of the map along algebraic curves. We will see that the IDPs are
singular loci of the curves.


title: Analog Signal Processing

abstract:
  Analog signal processing (ASP) is presented as a systematic approach to
address future challenges in high speed and high frequency microwave
applications. The general concept of ASP is explained with the help of examples
emphasizing basic ASP effects, such as time spreading and compression, chirping
and frequency discrimination. Phasers, which represent the core of ASP systems,
are explained to be elements exhibiting a frequency-dependent group delay
response, and hence a nonlinear phase response versus frequency, and various
phaser technologies are discussed and compared. Real-time Fourier
transformation (RTFT) is derived as one of the most fundamental ASP operations.
Upon this basis, the specifications of a phaser resolution, absolute bandwidth
and magnitude balance are established, and techniques are proposed to enhance
phasers for higher ASP performance. Novel closed-form synthesis techniques,
applicable to all-pass transmission-type cascaded Csection phasers, all-pass
reflection-type coupled resonator phasers and band-pass cross-coupled resonator
phasers are described. Several applications using these phasers are presented,
including a tunable pulse delay system, a spectrum sniffer and a realtime
spectrum analyzer (RTSA). Finally, future challenges and opportunities are
discussed.


title: Half-Magnetization Plateau of a Dipolar Spin Ice in a [100] Field

abstract:
  We report here numerical results of the low-temperature behavior of a dipolar
spin ice in a magnetic field along the [100] direction. Tuning the magnetic
field, the system exhibit a half-magnetization plateau at low temperature. This
half-polarized phase should correspond to a quantum solid phase in an effective
2D quantum boson model, and the transition from the Coulomb phase with a
power-law correlation to this state can be regarded as a superfluid to a
quantum solid transition. We discuss possible experimental signatures of this
half-polarized state.


title:
Complex order-parameter phase-field models derived from structural
  phase-field-crystal models

abstract:
  The phase-field-crystal (PFC) modeling paradigm is rapidly emerging as the
model of choice when investigating materials phenomena with atomistic scale
effects over diffusive time scales. Recent variants of the PFC model, so-called
structural PFC (XPFC) models introduced by Greenwood et al., have further
increased the capability of the method by allowing for easy access to various
structural transformations in pure materials [Phys. Rev. Lett. 105, 045702
(2010)] and binary alloys [Phys. Rev. B. 84, 064104, (2011)]. We present an
amplitude expansion of these XPFC models, leading to a mesoscale complex
order-parameter (amplitude), i.e., phase-field representation, model for two
dimensional square-triangular structures. Amplitude models retain the salient
atomic scale features of the underlying PFC models, while resolving
microstructures on mesoscales as in traditional phase-field models. The
applicability and capability of this complex amplitude model is demonstrated
with simulations of peritectic solidification and grain growth exhibiting the
emergence of secondary phase structures.


title: On lattices with finite Coulombian interaction energy in the plane

abstract:
  Given a discrete set $\Lambda$ in the plane (we will also say a {\em
lattice}) and a real number $m\ge 0$, the renormalized energy introduced in
\cite{ss1} heuristically describes the interaction energy of unit charges
placed at the points of $\Lambda$ with a uniform negative background of density
$m\in\R$. It is defined in several steps, following mostly \cite{ss1}.


title:
Investigating possible decay modes of $Y(4260)$ under the $D_1(2420)\bar
  D +c.c$ molecular state ansatz

abstract:
  By assuming that $Y(4260)$ is a $D_1\bar D$ molecular state, we investigate
some hidden-charm and charmed pair decay channels of $Y(4260)$ via intermediate
$D_1\bar D$ meson loops with an effective Lagrangian approach. Through
investigating the $\alpha$-dependence of branching ratios and ratios between
different decay channels, we show that the intermediate $D_1 \bar D$ meson
loops are crucial for driving these transitions of $Y(4260)$ studied here. The
coupled channel effects turn out to be more important in $Y(4260) \to
D^{*}\bar{D}^{*}$, which can be tested in the future experiments.


title:
$(p,q)-$deformed Fibonacci and Lucas polynomials: characterization and
  Fourier integral transforms

abstract:
  A full characterization of $(p,q)$-deformed Fibonacci and Lucas polynomials
is given. These polynomials obey non-conventional three-term recursion
relations. Their generating functions and Fourier integral transforms are
explicitly computed and discussed. Relevant results known in the literature are
examined as particular cases.


title: Ponzano-Regge Model on Manifold with Torsion

abstract:
  The connection between angular momentum in quantum mechanics and geometric
objects is extended to manifold with torsion. First, we notice the relation
between the $6j$ symbol and Regge's discrete version of the action functional
of Euclidean three dimensional gravity with torsion, then consider the Ponzano
and Regge asymptotic formula for the Wigner $6j$ symbol on this simplicial
manifold with torsion. In this approach, a three dimensional manifold $M$ is
decomposed into a collection of tetrahedra, and it is assumed that each
tetrahedron is filled in with flat space and the torsion of $M$ is concentrated
on the edges of the tetrahedron, the length of the edge is chosen to be
proportional to the length of the angular momentum vector in semiclassical
limit. The Einstein-Hilbert action is then a function of the angular momentum
and the Burgers vector of dislocation, and it is given by summing the Regge
action over all tetrahedra in $M$. We also discuss the asymptotic approximation
of the partition function and their relation to the Feynmann path integral for
simplicial manifold with torsion without cosmological constant.


title: Distribution of Angular Momentum in the Transverse Plane

abstract:
  Fourier transforms of GPDs describe the distribution of partons in the
transverse plane. The 2nd moment of GPDs has been identified by X.Ji with the
angular momentum (orbital plus spin) carried by the quarks - a fundamental
result that is being widely utilized in the spin decomposition of a
longitudinally polarized nucleon. However, I will demonstrate that, despite the
above results, the Fourier transform of the 2nd moment of GPDs does not
describe the distribution of angular momentum in the transverse plane for a
longitudinally polarized target.


title: Excitation Function of the nat-Ta(p,x)178m2-Hf Reaction

abstract:
  178m2-Hf is an extremely interesting isomeric state due to its potential
energy capacity level. One possible way to obtain it is by irradiation of a
nat-Ta sample with a high-current proton accelerator. Up to now, there was no
information in the international experimental nuclear data base (EXFOR) for
this reaction. Irradiations of nat-Ta samples performed for other purposes
provide an opportunity to address this question. This paper presents the
172m2-Hf independent production cross-sections determined by gamma-ray
spectrometry. The nat-Ta(p,x)172m2-Hf excitation function is studied in the
20-3500 MeV energy range. Comparisons with results by several nuclear models
(ISABEL, Bertini, INCL4.5+ABLA07, PHITS, CASCADE07, and CEM03.02) used as
event-generators in modern transport codes are also reported. However, since
such models are generally not able to separately predict ground and isomeric
states of reaction products, only 178-Hf independent and cumulative
cross-section data are compared.


title:
Herschel PACS observations of shocked gas associated with the jets of
  L1448 and L1157

abstract:
  In the framework of the WISH key program, several H2O (E_u>190 K), high-J CO,
[OI], and OH transitions are mapped with PACS in two shock positions along the
two prototypical low-luminosity outflows L1448 and L1157. Previous HIFI H2O
observations (E_u=53-249 K) and complementary Spitzer mid-IR H2 data are also
used, with the aim of deriving a complete picture of the excitation conditions.
At all selected spots a close spatial association between H2O, mid-IR H2, and
high-J CO emission is found, whereas the low-J CO emission traces either
entrained ambient gas or a remnant of an older shock. The excitation analysis
at L1448-B2 suggests that a two-component model is needed to reproduce the H2O,
CO, and mid-IR H2 lines: an extended warm component (T~450 K) is traced by the
H2O emission with E_u =53-137 K and by the CO lines up to J=22-21, and a
compact hot component (T=1100 K) is traced by the H2O emission with E_u>190 K
and by the higher-J CO lines. At L1448-B2 we obtain an H2O abundance
(3-4)x10^{-6} for the warm component and (0.3-1.3)x10^{-5} for the hot
component; we also detect OH and blue-shifted [OI] emission, spatially
coincident with the other molecular lines and with [FeII] emission. This
suggests a dissociative shock for these species, related to the embedded atomic
jet. On the other hand, a non-dissociative shock at the point of impact of the
jet on the cloud is responsible for the H2O and CO emission. The other examined
shock positions show an H2O excitation similar to L1448-B2, but a slightly
higher H2O abundance (a factor of 4). The two gas components may represent a
gas stratification in the post-shock region. The extended and low-abundance
warm component traces the post-shocked gas that has already cooled down to a
few hundred Kelvin, whereas the compact and possibly higher-abundance hot
component is associated with the gas that is currently undergoing a shock
episode.


title:
Quantifying many-body effects by high-resolution Fourier transform
  scanning tunneling spectroscopy

abstract:
  Many-body phenomena are ubiquitous in solids, as electrons interact with one
another and the many excitations arising from lattice, magnetic, and electronic
degrees of freedom. These interactions can subtly influence the electronic
properties of materials ranging from metals, exotic materials such as graphene,
and topological insulators, or they can induce new phases of matter, as in
conventional and unconventional superconductors, heavy fermion systems, and
other systems of correlated electrons. As no single theoretical approach
describes all such phenomena, the development of versatile methods for
measuring many-body effects is key for understanding these systems. To date,
angle-resolved photoemission spectroscopy (ARPES) has been the method of choice
for accessing this physics by directly imaging momentum resolved electronic
structure. Scanning tunneling microscopy/spectroscopy (STM/S), renown for its
real-space atomic resolution capability, can also access the electronic
structure in momentum space using Fourier transform scanning tunneling
spectroscopy (FT-STS). Here, we report a high-resolution FT-STS measurement of
the Ag(111) surface state, revealing fine structure in the otherwise parabolic
electronic dispersion. This deviation is induced by interactions with lattice
vibrations and has not been previously resolved by any technique. This study
advances STM/STS as a method for quantitatively probing many-body interactions.
Combined with the spatial sensitivity of STM/STS, this technique opens a new
avenue for studying such interactions at the nano-scale.


title: The Parkes Pulsar Timing Array

abstract:
  The aims of the Parkes Pulsar Timing Array (PPTA) project are to 1) make a
direct detection of gravitational waves, 2) improve the solar system planetary
ephemeris and 3) develop a pulsar-based time scale. In this article we describe
the project, explain how the data are collected and processed and describe
current research. Our current data sets are able to place an upper bound on the
gravitational wave background that is the most stringent to date.


title: Amplification limit of weak measurements: a variational approach

abstract:
  Post-selected weak measurement has been widely used in experiments to observe
weak effects in various physical systems. However, it is still unclear how
large the amplification ability of a weak measurement can be and what
determines the limit of this ability, which is fundamental to understanding and
applying weak measurements. The limitation of the conventional weak value
formalism for this problem is the divergence of weak values when the pre- and
post-selections are nearly orthogonal. In this paper, we study this problem by
a variational approach for a general Hamiltonian
$H_{\mathrm{int}}=gA\otimes\Omega\delta(t-t_{0}),\, g\ll1$. We derive a general
asymptotic solution, and show that the amplification limit is essentially
independent of $g$, and determined only by the initial state of the detector
and the number of distinct eigenvalues of $A$ or $\Omega$. An example of
spin-$\frac{1}{2}$ particles with a pair of Stern-Gerlach devices is given to
illustrate the results. The limiting case of continuous variable systems is
also investigated to demonstrate the influence of system dimension on the
amplification limit.


title: Orbifold Family Unification on 6 Dimensions

abstract:
  We study the possibility of family unification on the basis of SU(N) gauge
theory on the 6-dimensional space-time, $M^4\times T^2/Z_N$. We obtain enormous
numbers of models with three families of SU(5) matter multiplets and those with
three families of the standard model multiplets, from a single massless Dirac
fermion with a higher-dimensional representation of SU(N), through the orbifold
breaking mechanism.


title: Imprint of primordial non-Gaussianity on dark matter halo profiles

abstract:
  We study the impact of primordial non-Gaussianity on the density profile of
dark matter halos by using the semi-analytical model introduced recently by
Dalal {\it et al.} which relates the peaks of the initial linear density field
to the final density profile of dark matter halos. Models with primordial
non-Gaussianity typically produce an initial density field that differs from
that produced in Gaussian models. We use the path-integral formulation of
excursion set theory to calculate the non-Gaussian corrections to the peak
profile and derive the statistics of the peaks of non-Gaussian density field.
In the context of the semi-analytic model for halo profiles, currently allowed
values for primordial non-Gaussianity would increase the shapes of the inner
dark matter profiles, but only at the sub-percent level except in the very
innermost regions.


title: Non-Doppler Redshift and Redshifts of QSOs

abstract:
  Quasars have reigned as the most luminous and distant objects in the
Universe. These concepts were based on the hypothesis that the redshifts of
quasars are obeying the Hubble low. This hypothesis has little serious
competition today, but has met some difficulties when using it to determine the
distances of quasars. However, the majority of the redshifts of quasars can be
explained by the soft photon process proposed by Zheng (2013), then quasars are
not located at the distances as that calculated from observed redshifts
according to the Hubble low. Therefore distances of quasars can be reduced to a
reasonable range, and the difficulties have met by quasars disappeared.


title:
Inverting Spherical Radon Transform by a Closed-form Formula: A
  Microlocal Analytic Point of View

abstract:
  Let $\mR$ be the restriction of the spherical Radon transform to the set of
spheres centered on a hypersurface $\mS$. We study the inversion of $\mR$ by a
closed-form formula. We approach the problem by studying an oscillatory
integral, which depends on the observation surface $\mS$ as a parameter. We
then derive various microlocal analytic properties of the associated
closed-form inversion formula.


title:
Explaining the [CII]158um Deficit in Luminous Infrared Galaxies - First
  Results from a Herschel/PACS Study of the GOALS Sample

abstract:
  We present the first results of a survey of the [CII]158um emission line in
241 luminous infrared galaxies (LIRGs) comprising the Great Observatories
All-sky Survey (GOALS) sample, obtained with the PACS instrument on board
Herschel. The [CII] luminosities of the LIRGs in GOALS range from ~10^7 to
2x10^9 Lsun. We find that LIRGs show a tight correlation of [CII]/FIR with
far-IR flux density ratios, with a strong negative trend spanning from ~10^-2
to 10^-4, as the average temperature of dust increases. We find correlations
between the [CII]/FIR ratio and the strength of the 9.7um silicate absorption
feature as well as with the luminosity surface density of the mid-IR emitting
region (Sigma_MIR), suggesting that warmer, more compact starbursts have
substantially smaller [CII]/FIR ratios. Pure star-forming (SF) LIRGs have a
mean [CII]/FIR ~ 4x10^-3, while galaxies with low 6.2um PAH equivalent widths
(EWs), indicative of the presence of active galactic nuclei (AGN), span the
full range in [CII]/FIR. However, we show that even when only pure SF galaxies
are considered, the [CII]/FIR ratio drops by an order of magnitude, from 10^-2
to 10^-3, with Sigma_MIR and Sigma_IR, implying that the [CII] luminosity is
not a good indicator of the star formation rate (SFR) for most LIRGs, for it
does not scale linearly with the warm dust emission. Moreover, even in LIRGs in
which we detect an AGN in the mid-IR, the majority (2/3) of galaxies show
[CII]/FIR >= 10^-3 typical of high 6.2um PAH EW sources, suggesting that most
AGNs do not contribute significantly to the far-IR emission. We provide an
empirical relation between the [CII]/FIR and the specific SFR (SSFR) for SF
LIRGs. Finally, we present predictions for the starburst size based on the
observed [CII] and far-IR luminosities which should be useful for comparing
with results from future surveys of high-redshift galaxies with ALMA and CCAT.


title: BEC and dimensional crossover in a boson gas within multi-slabs

abstract:
  For an ideal Bose-gas within a multi-slabs periodic structure, we report a
dimensional crossover and discuss whether a BEC transition at $T_c \neq 0$
disappears or not.
  The multi-slabs structure is generated via a Kronig-Penney potential
perpendicular to the slabs of width $a$ and separated by a distance $b$. The
ability of the particles to jump between adjacent slabs is determined by the
hight $V_0$ and width $b$ of the potential barrier. Contrary to what happens in
the boson gas inside a zero-width multilayers case, where the critical
temperature diminishes and goes up again as a function of the wall separation,
here the $T_c$ decreases continuously as the potential barrier height and the
cell size $a+b$ increase. We plot the surface $T_c = 10^{-6}$ showing two
prominent regions in the parameters space, which suggest a phase transition
BEC-NOBEC at $T \neq 0$. %The position of the phase transition surface is
almost independent of the ratio $r=b/a$ while the cell size $a+b$ is almost
proportional to the square root of the height of the potential barriers. The
specific heat shows a crossover from 3D to 2D when the height of the potential
or the barrier width increase, in addition to the well known peak related to
the Bose-Einstein condensation.


title: New limits on the violation of local position invariance of gravity

abstract:
  Within the parameterized post-Newtonian (PPN) formalism, there could be an
anisotropy of local gravity induced by an external matter distribution, even
for a fully conservative metric theory of gravity. It reflects the breakdown of
the local position invariance of gravity and, within the PPN formalism, is
characterized by the Whitehead parameter $\xi$. We present three different
kinds of observation, from the Solar system and radio pulsars, to constrain it.
The most stringent limit comes from recent results on the extremely stable
pulse profiles of solitary millisecond pulsars, that gives $|\hat \xi| < 3.9
\times 10^{-9}$ (95% CL), where the hat denotes the strong-field generalization
of $\xi$. This limit is six orders of magnitude more constraining than the
current best limit from superconducting gravimeter experiments. It can be
converted into an upper limit of $\sim 4 \times 10^{-16}$ on the spatial
anisotropy of the gravitational constant.


title:
Determining the Hubble constant from gravitational wave observations of
  merging compact binaries

abstract:
  Recent observations have accumulated compelling evidence that some short
gamma-ray bursts (SGRBs) are associated with the mergers of neutron star (NS)
binaries. This would indicate that the SGRB event is associated with a
gravitational-wave (GW) signal corresponding to the final inspiral of the
compact binary. In addition, the radioactive decay of elements produced in NS
binary mergers may result in transients visible in the optical and infrared
with peak luminosities on hours-days timescales. Simultaneous observations of
the inspiral GWs and signatures in the electromagnetic band may allow us to
directly and independently determine both the luminosity distance and redshift
to a binary. These standard sirens (the GW analog of standard candles) have the
potential to provide an accurate measurement of the low-redshift Hubble flow.
In addition, these systems are absolutely calibrated by general relativity, and
therefore do not experience the same set of astrophysical systematics found in
traditional standard candles, nor do the measurements rely on a distance
ladder. We show that 15 observable GW and EM events should allow the Hubble
constant to be measured with 5% precision using a network of detectors that
includes advanced LIGO and Virgo. Measuring 30 beamed GW-SGRB events could
constrain H_0 to better than 1%. When comparing to standard Gaussian likelihood
analysis, we find that each event's non-Gaussian posterior in H_0 helps reduce
the overall measurement errors in H_0 for an ensemble of NS binary mergers.


title: Variational symmetries and pluri-Lagrangian systems

abstract:
  We analyze the relation of the notion of pluri-Lagrangian systems, which
recently emerged in the theory of integrable systems, to the classical notion
of variational symmetry, due to E. Noether.