title: Early Modified Gravity: Implications for Cosmology

abstract:
  We study the effects of modifications of gravity after Big Bang
Nucleosynthesis (BBN) which would manifest themselves mainly before
recombination. We consider their effects on the Cosmic Microwave Background
(CMB) radiation and on the formation of large scale structure. The models that
we introduce here represent all screened modifications of General Relativity
(GR) which evade the local tests of gravity such as the violation of the strong
equivalence principle as constrained by the Lunar Ranging experiment. We use
the tomographic description of modified gravity which defines models with
screening mechanisms of the chameleon or Damour-Polyakov types and allows one
to relate the temporal evolution of the mass and the coupling to matter of a
scalar field to its Lagrangian and also to cosmological perturbations. The
models with early modifications of gravity all involve a coupling to matter
which is stronger in the past leading to effects on perturbations before
recombination while minimising deviations from Lambda-CDM structure formation
at late times. We find that a new family of early transition models lead to
discrepancies in the CMB spectrum which could reach a few percent and appear as
both enhancements and reductions of power for different scales.


title:
First Principles Study of Bismuth Films at Transition Metal Grain
  Boundaries

abstract:
  Recent experiments suggest that Bi impurities segregate to form bilayer films
on Ni and Cu grain boundaries but do not segregate in Fe. To explain these
phenomena, we study the total energies of Bi films on transition metal (TM)
$\Sigma$3(111) and $\Sigma$5(012) GBs using density functional theory. Our
results agree with the observed stabilities. We propose a model to predict Bi
bilayer stability at Ni GBs which suggests that Bi bilayer is not stable on
(111) twist CSL GBs but is stable in most (100) twist CSL GBs. We investigate
the interaction and bonding character between Bi and TMs to explain the
differences among TMs based on localization of orbitals and magnetism.


title:
Radio-frequency dispersive detection of donor atoms in a field-effect
  transistor

abstract:
  Radio-frequency dispersive read-out can provide a useful probe to nano-scale
structures such as nano-wire devices, especially when the implementation of
charge sensing is not straightforward. Here we demonstrate dispersive
`gate-only' read-out of phosphor donors in a silicon nano-scale transistor. The
technique enables access to states that are only tunnel-coupled to one contact,
which is not easily achievable by other methods. This allows us to locate
individual randomly placed donors in the device channel. Furthermore, the setup
is naturally compatible with high bandwidth access to the probed donor states
and may aid the implementation of a qubit based on coupled donors.


title: Low-threshold stimulated emission using colloidal quantum wells

abstract:
  Semiconductor nanocrystals can be synthesized using inexpensive, scalable,
solution-based techniques, and their utility as tunable light emitters has been
demonstrated in various applications, including biolabeling and light-emitting
devices. By contrast, the use of colloidal nanocrystals for optical
amplification and lasing has been limited by the high input power densities
that have been required. In this work, we show that colloidal nanoplatelets
(NPLs) produce amplified spontaneous emission (ASE) with pump-fluence
thresholds as low 6 uJ/cm2 and gain as high as 600 cm-1, both a 4-fold
improvement over the best reported values for colloidal nanocrystals; in
addition, gain saturation occurs at pump fluences two orders of magnitude
higher than the ASE threshold. We attribute this exceptional performance to
large optical cross-sections, slow Auger recombination rates, and the narrow
emission linewidth of the NPL ensemble. The NPLs bring the advantages of
quantum wells as an optical gain medium to a colloidal system, opening up the
possibility of producing high-efficiency, solution-processed lasers.


title: Nonlinear Spectroscopy of Controllable Many-Body Quantum Systems

abstract:
  We establish a novel approach to probing spatially resolved multi-time
correlation functions of interacting many-body systems, with scalable
experimental overhead. Specifically, designing nonlinear measurement protocols
for multidimensional spectra in a chain of trapped ions with single-site
addressability enables us, e.g., to distinguish coherent from incoherent
transport processes, to quantify potential anharmonicities, and to identify
decoherence-free subspaces.


title: Quantum fluctuations from a local-causal information dynamics

abstract:
  We shall show that the abstract and formal rules which govern the quantum
kinematic and dynamics can be derived from a law of change of the information
content or the degree of uncertainty that the system has a certain
configuration in a microscopic time scale, which is singled out uniquely, up to
a free parameter, by imposing the condition of Macroscopic Classicality and the
principle of Locality. Unlike standard quantum mechanics, however, the system
always has a definite configuration all the time as in classical mechanics,
following a continuous trajectory fluctuating randomly in time.


title:
A High-Resolution X-Ray and Optical Study of SN 1006: Asymmetric
  Expansion and Small-Scale Structure in a Type Ia Supernova Remnant

abstract:
  We introduce a deep (670 ks) X-ray survey of the SN1006 remnant from Chandra,
plus a deep H-alpha image from the 4m telescope at CTIO. Comparison with
Chandra images from 2003 gives the first measurement of X-ray proper motions
around the entire rim. We find that the expansion velocity varies significantly
with azimuth: the highest velocity of ~7400 km/s (almost 2.5 times that in the
NW) is found along the SE rim, where both kinematics and spectra indicate that
most of the X-rays stem from undecelerated ejecta. Asymmetries in the
distribution of ejecta are seen on a variety of spatial scales. Si-rich ejecta
are especially prominent in the SE quadrant, while O and Mg are more uniformly
distributed, indicating large-scale asymmetries arising from the explosion
itself. Ne emission is strongest in a sharp filament just behind the primary
shock along the NW rim, where the preshock density is highest. Here the Ne is
likely interstellar, while Ne within the shell may include a contribution from
ejecta. Within the interior of the projected shell we find a few isolated
"bullets" of what appear to be supernova ejecta that are immediately preceded
by bowshocks seen in H-alpha--features we interpret as ejecta knots that have
reached relatively dense regions of the surrounding ISM. Recent 3-dimensional
hydrodynamic models for SN Ia display small-scale features that resemble the
ones seen in X-rays in SN1006; an origin in the explosion itself or from
subsequent instabilities both remain viable options. We have expanded the
search for precursor X-ray emission ahead of a synchrotron-dominated shock
front. Profiles along both NE and SW rims require that a precursor be thinner
than about 3 arcsec and fainter than about 5% of the post-shock peak. These
limits suggest that the magnetic field is amplified by a factor of 7 or more in
a narrow precursor region, promoting diffusive particle acceleration.


title: New Codes on Graphs Constructed by Connecting Spatially Coupled Chains

abstract:
  A novel code construction based on spatially coupled low-density parity-check
(SC-LDPC) codes is presented. The proposed code ensembles are described by
protographs, comprised of several protograph-based chains characterizing
individual SC-LDPC codes. We demonstrate that code ensembles obtained by
connecting appropriately chosen SC-LDPC code chains at specific points have
improved iterative decoding thresholds compared to those of single SC-LDPC
coupled chains. In addition, it is shown that the improved decoding properties
of the connected ensembles result in reduced decoding complexity required to
achieve a specific bit error probability. The constructed ensembles are also
asymptotically good, in the sense that the minimum distance grows linearly with
the block length. Finally, we show that the improved asymptotic properties of
the connected chain ensembles also translate into improved finite length
performance.


title: Nanoemulsions obtained via bubble bursting at a compound interface

abstract:
  The bursting of bubbles at an air/liquid interface is a familiar occurrence
important to foam stability, cell cultures in bioreactors and mass transfer
between the sea and atmosphere. Here we document the hitherto unreported
formation and dispersal into the water column of submicrometre oil droplets
following bubble bursting at a compound air/oil/water-with-surfactant
interface. We show that dispersal results from the detachment of an oil spray
from the bottom of the bubble towards water during bubble collapse. We provide
evidence that droplet size is selected by physicochemical interactions between
oil molecules and the surfactants rather than by hydrodynamic effects. We
illustrate the unrecognized role that this dispersal mechanism may play in the
fate of the sea surface micro-layer and of pollutant spills by dispersing
petroleum in the water column. Finally, our system provides an energy-efficient
route, with potential upscalability and wide applicability, for applications in
drug delivery, food production and material science, which we demonstrate by
producing polymeric nanoparticles.


title:
Radiation Transfer of Models of Massive Star Formation. III. The
  Evolutionary Sequence

abstract:
  We present radiation transfer (RT) simulations of evolutionary sequences of
massive protostars forming from massive dense cores in environments of high
surface densities. The protostellar evolution is calculated with a detailed
multi-zone model, with the accretion rate regulated by feedback from an
evolving disk-wind outflow cavity. Disk and envelope evolutions are calculated
self-consistently. In this framework, an evolutionary track is determined by
three environmental initial conditions: the initial core mass M_c, the mean
surface density of the ambient star-forming clump Sigma_cl, and the
rotational-to-gravitational energy ratio of the initial core, beta_c.
Evolutionary sequences with various M_c, Sigma_cl, beta_c are constructed. We
find that in a fiducial model with M_c=60Msun, Sigma_cl=1 g/cm^2 and
beta_c=0.02, the final star formation efficiency >~0.43. For each evolutionary
track, RT simulations are performed at selected stages, with temperature
profiles, SEDs, and images produced. At a given stage the envelope temperature
is highly dependent on Sigma_cl, but only weakly dependent on M_c. The SED and
MIR images depend sensitively on the evolving outflow cavity, which gradually
wides as the protostar grows. The fluxes at <~100 microns increase
dramatically, and the far-IR peaks move to shorter wavelengths. We find that,
despite scatter caused by different M_c, Sigma_cl, beta, and inclinations,
sources at a given evolutionary stage appear in similar regions on color-color
diagrams, especially when using colors at >~ 70 microns, where the scatter due
to the inclination is minimized, implying that such diagrams can be useful
diagnostic tools of evolutionary stages of massive protostars. We discuss how
intensity profiles along or perpendicular to the outflow axis are affected by
environmental conditions and source evolution.


title: Aspects of line operators of class S theories

abstract:
  Geometric picture of line operators of N=2 class S theories was found by
imposing closure condition on operator product expansion (OPE) of line
operators. In this paper, we first identify the geometric representation of
ordinary Wilson-'t Hooft line operators of field theory, and study duality
action on them. We further define a Dirac product between line operators and
classify the allowed set of line operators by requiring: a: closure of OPE; b:
mutual locality; c: maximality. Using above classifications, we find many
distinct gauge theories associated with a single duality frame, and show
explicitly that new possibilities correspond to the choice of global form of
gauge group and discrete theta angles. We also study S and T duality actions
relating those theories. In particular, we find very interesting duality webs
for Maldacena-Nunez theory.


title: On resources and tasks

abstract:
  Essentially being an extended abstract of the author's 1998 PhD thesis, this
paper introduces an extension of the language of linear logic with a semantics
which treats sentences as tasks rather than true/false statements. A resource
is understood as an agent capable of accomplishing the task expressed by such a
sentence. It is argued that the corresponding logic can be used as a planning
logic, whose advantage over the traditional comprehensive planning logics is
that it avoids the representationalframe problem and significantly alleviates
the inferential frame problem.


title:
Larger-area single-mode photonic crystal surface-emitting lasers enabled
  by an accidental Dirac point

abstract:
  By altering the lattice geometry of the photonic crystal surface-emitting
lasers (PCSELs), we tune the regular lasing band edges of quadratic dispersions
to form a single accidental Dirac point of linear dispersion at the Brillouin
zone center. This not only increases the mode spacing by orders of magnitude,
but also eliminates the distributed in-plane feedback to enable single-mode
PCSELs of substantially larger area thus substantially higher output power. The
advantages of using accidental Dirac cones are systematically evaluated through
two-dimensional in-plane calculations and confirmed by three-dimensional
simulations of photonic crystal slab devices.


title:
Controlled Connectivity for Semi-Direct Products Acting on Locally
  Finite Trees

abstract:
  In 2003 Bieri and Geoghegan generalized the Bieri-Neuman-Strebel invariant
$\Sigma^1$ by defining $\Sigma^1(\rho)$, $\rho$ an isometric action by a
finitely generated group $G$ on a proper CAT(0) space $M$. In this paper, we
show how the natural and well-known connection between Bass-Serre theory and
covering space theory provides a framework for the calculation of
$\Sigma^1(\rho)$ when $\rho$ is a cocompact action by $G = B \rtimes A$, $A$ a
finitely generated group, on a locally finite Bass-Serre tree $T$ for $A$. This
framework leads to a theorem providing conditions for including an endpoint in,
or excluding an endpoint from, $\Sigma^1(\rho)$. When $A$ is a finitely
generated free group acting on its Cayley graph, we can restate this theorem
from a more algebraic perspective, which leads to some general results on
$\Sigma^1$ for such actions.


title:
Strange magnetic form factor of nucleon in heavy baryon chiral effective
  approach at next to leading order

abstract:
  The strange magnetic form factor of the nucleon is studied in the heavy
baryon chiral effective approach at next to leading order. The one loop
contributions from kaon and intermediate octet and decuplet hyperons are
included, using finite-range-regularization to deal with the ultra-violet
divergences. Drawing on an established connection between quenched and full
QCD, this model makes it possible to predict the strange magnetic form factor
under the hypothesis that for a dipole regulator mass $\Lambda$ around 0.8 GeV,
strangeness in the core is negligible. The strange magnetic form factor is
found to be small and negative over a range of momentum transfer, while the
strange magnetic moment is consistent with the best lattice QCD determinations.


title:
Nonlinear modes and symmetries in linearly-coupled pairs of PT-invariant
  dimers

abstract:
  The subject of the work are pairs of linearly coupled PT-symmetric dimers.
Two different settings are introduced, namely, straight-coupled dimers, where
each gain site is linearly coupled to one gain and one loss site, and
cross-coupled dimers, with each gain site coupled to two lossy ones. The latter
pair with equal coupling coefficients represents a "PT-hypersymmetric"
quadrimer. We find symmetric and antisymmetric solutions in these systems,
chiefly in an analytical form, and explore the existence, stability and
dynamical behavior of such solutions by means of numerical methods. We thus
identify bifurcations occurring in the systems, including spontaneous symmetry
breaking and saddle-center bifurcations. Simulations demonstrate that evolution
of unstable branches typically leads to blowup. However, in some cases unstable
modes rearrange into stable ones.


title:
Sensitivity of a Future High Energy $e^+ e^-$ Collider to $Z^\prime$
  Bosons

abstract:
  We consider the capability of a future high energy $e^+ e^-$ collider to
search for the $Z^\prime$ bosons associated with a $U(1)^\prime$ gauge
extension of the Standard Model. Even for $Z^\prime$ masses well above the
center of mass energy of the collider, the rates of production of $e^+ e^-$,
$\mu^+ \mu^-$, unflavored jets, and $b$-tagged jets can reveal the presence of
virtual $Z^\prime$ exchange. We consider collider configurations with
center-of-mass energy 200, 300, and 500 GeV, and show how various classes of
$Z^\prime$ model-lines can be probed with $100~{\rm fb}^{-1}$ of integrated
luminosity. We find that for order one couplings, $Z^\prime$ masses on the
order of several TeV can be discovered, depending on the collider energy. Our
results suggest that a 200 GeV collision energy is unlikely to discover any of
the $Z^\prime$ models we consider that would not have already been visible in
late stages of LHC running, but could still help refine understanding of the
couplings and distinguish between different models. For $e^+ e^-$ collision
energies of 300 GeV, parameter space beyond the reach of the LHC becomes
accessible.


title:
Expectation Propagation for Nonlinear Inverse Problems -- with an
  Application to Electrical Impedance Tomography

abstract:
  In this paper, we study a fast approximate inference method based on
expectation propagation for exploring the posterior probability distribution
arising from the Bayesian formulation of nonlinear inverse problems. It is
capable of efficiently delivering reliable estimates of the posterior mean and
covariance, thereby providing an inverse solution together with quantified
uncertainties. Some theoretical properties of the iterative algorithm are
discussed, and the efficient implementation for an important class of problems
of projection type is described. The method is illustrated with one typical
nonlinear inverse problem, electrical impedance tomography with complete
electrode model, under sparsity constraints. Numerical results for real
experimental data are presented, and compared with that by Markov chain Monte
Carlo. The results indicate that the method is accurate and computationally
very efficient.


title:
On RIC bounds of Compressed Sensing Matrices for Approximating Sparse
  Solutions Using $\ell_q$ Quasi Norms

abstract:
  This paper follows the recent discussion on the sparse solution recovery with
quasi-norms $\ell_q,~q\in(0,1)$ when the sensing matrix possesses a Restricted
Isometry Constant $\delta_{2k}$ (RIC). Our key tool is an improvement on a
version of "the converse of a generalized Cauchy-Schwarz inequality" extended
to the setting of quasi-norm. We show that, if $\delta_{2k}\le 1/2$, any
minimizer of the $l_q$ minimization, at least for those $q\in(0,0.9181]$, is
the sparse solution of the corresponding underdetermined linear system.
Moreover, if $\delta_{2k}\le0.4931$, the sparse solution can be recovered by
any $l_q, q\in(0,1)$ minimization. The values $0.9181$ and $0.4931$ improves
those reported previously in the literature.


title:
Pressure-induced superconductivity in EuFe2As2 without a quantum
  critical point: magnetotransport and upper critical field measurements under
  high pressure

abstract:
  Resistivity and Hall effect measurements of EuFe$_2$As$_2$ up to 3.2\,GPa
indicate no divergence of quasiparticle effective mass at the pressure
$P_\mathrm{c}$ where the magnetic and structural transition disappears. This is
corroborated by analysis of the temperature ($T$) dependence of the upper
critical field. $T$-linear resistivity is observed at pressures slightly above
$P_\mathrm{c}$. The scattering rates for both electrons and holes are shown to
be approximately $T$-linear. When a field is applied, a $T^2$ dependence is
recovered, indicating that the origin of the $T$-linear dependence is spin
fluctuations.


title: An extension problem for the CR fractional Laplacian

abstract:
  We show that the conformally invariant fractional powers of the sub-Laplacian
on the Heisenberg group are given in terms of the scattering operator for an
extension problem to the Siegel upper halfspace. Remarkably, this extension
problem is different from the one studied, among others, by Caffarelli and
Silvestre.


title:
Robustly detecting differential expression in RNA sequencing data using
  observation weights

abstract:
  A popular approach for comparing gene expression levels between (replicated)
conditions of RNA sequencing data relies on counting reads that map to features
of interest. Within such count-based methods, many flexible and advanced
statistical approaches now exist and offer the ability to adjust for covariates
(e.g., batch effects). Often, these methods include some sort of (sharing of
information) across features to improve inferences in small samples. It is
important to achieve an appropriate tradeoff between statistical power and
protection against outliers. Here, we study the robustness of existing
approaches for count-based differential expression analysis and propose a new
strategy based on observation weights that can be used within existing
frameworks. The results suggest that outliers can have a global effect on
differential analyses. We demonstrate the effectiveness of our new approach
with real data and simulated data that reflects properties of real datasets
(e.g., dispersion-mean trend) and develop an extensible framework for
comprehensive testing of current and future methods. In addition, we explore
the origin of such outliers, in some cases highlighting additional biological
or technical factors within the experiment. Further details can be downloaded
from the project website:
http://imlspenticton.uzh.ch/robinson_lab/edgeR_robust/


title:
Maxwell's macroscopic equations, the energy-momentum postulates, and the
  Lorentz law of force

abstract:
  We argue that the classical theory of electromagnetism is based on Maxwell's
macroscopic equations, an energy postulate, a momentum postulate, and a
generalized form of the Lorentz law of force. These seven postulates constitute
the foundation of a complete and consistent theory, thus eliminating the need
for actual (i.e., physical) models of polarization P and magnetization M, these
being the distinguishing features of Maxwell's macroscopic equations. In the
proposed formulation, P(r,t) and M(r,t) are arbitrary functions of space and
time, their physical properties being embedded in the seven postulates of the
theory. The postulates are self-consistent, comply with the requirements of the
special theory of relativity, and satisfy the laws of conservation of energy,
linear momentum, and angular momentum. One advantage of the proposed
formulation is that it side-steps the long-standing Abraham-Minkowski
controversy surrounding the electromagnetic momentum inside a material medium
by simply "assigning" the Abraham momentum density E(r,t) x H(r,t)/c^2 to the
electromagnetic field. This well-defined momentum is thus taken to be universal
as it does not depend on whether the field is propagating or evanescent, and
whether or not the host medium is homogeneous, transparent, isotropic,
dispersive, magnetic, linear, etc. In other words, the local and instantaneous
momentum density is uniquely and unambiguously specified at each and every
point of the material system in terms of the E and H fields residing at that
point. Any variation with time of the total electromagnetic momentum of a
closed system results in a force exerted on the material media within the
system in accordance with the generalized Lorentz law.


title:
Unveiling the Structure of Barred Galaxies at 3.6 $\mu {\rm m}$ with the
  Spitzer Survey of Stellar Structure in Galaxies (S$^4$G): I. Disk Breaks

abstract:
  We have performed two-dimensional multicomponent decomposition of 144 local
barred spiral galaxies using 3.6 $\mu {\rm m}$ images from the Spitzer Survey
of Stellar Structure in Galaxies. Our model fit includes up to four components
(bulge, disk, bar, and a point source) and, most importantly, takes into
account disk breaks. We find that ignoring the disk break and using a single
disk scale length in the model fit for Type II (down-bending) disk galaxies can
lead to differences of 40% in the disk scale length, 10% in bulge-to-total
luminosity ratio (B/T), and 25% in bar-to-total luminosity ratios. We find that
for galaxies with B/T $\geq$ 0.1, the break radius to bar radius, $r_{\rm
br}/R_{\rm bar}$, varies between 1 and 3, but as a function of B/T the ratio
remains roughly constant. This suggests that in bulge-dominated galaxies the
disk break is likely related to the outer Lindblad Resonance (OLR) of the bar,
and thus moves outwards as the bar grows. For galaxies with small bulges, B/T
$<$ 0.1, $r_{\rm br}/R_{\rm bar}$ spans a wide range from 1 to 6. This suggests
that the mechanism that produces the break in these galaxies may be different
from that in galaxies with more massive bulges. Consistent with previous
studies, we conclude that disk breaks in galaxies with small bulges may
originate from bar resonances that may be also coupled with the spiral arms, or
be related to star formation thresholds.


title: Pointwise almost h-semi-slant submanifolds

abstract:
  We introduce the notions of pointwise almost h-slant submanifolds and
pointwise almost h-semi-slant submanifolds as a generalization of slant
submanifolds, pointwise slant submanifolds, semi-slant submanifolds, and
pointwise semi-slant submanifolds. We have characterizations and investigate
the integrability of distributions, the conditions for such distributions to be
totally geodesic foliations, the mean curvature vector fields on totally
umbilic submanifolds, the properties of h-slant functions and h-semi-slant
functions, the properties of non-trivial warped product proper pointwise
h-semi-slant submanifolds. We also obtain topological properties on proper
pointwise almost h-slant submanifolds and give an inequality for the squared
norm of the second fundamental form in terms of the warping function and
h-semi-slant functions for a warped product submanifold in a hyperk\"ahler
manifold. Finally, we give some examples of such submanifolds.


title:
Clustering for high-dimension, low-sample size data using distance
  vectors

abstract:
  In high-dimension, low-sample size (HDLSS) data, it is not always true that
closeness of two objects reflects a hidden cluster structure. We point out the
important fact that it is not the closeness, but the "values" of distance that
contain information of the cluster structure in high-dimensional space. Based
on this fact, we propose an efficient and simple clustering approach, called
distance vector clustering, for HDLSS data. Under the assumptions given in the
work of Hall et al. (2005), we show the proposed approach provides a true
cluster label under milder conditions when the dimension tends to infinity with
the sample size fixed. The effectiveness of the distance vector clustering
approach is illustrated through a numerical experiment and real data analysis.


title:
Navigating the massive world of reddit: Using backbone networks to map
  user interests in social media

abstract:
  In the massive online worlds of social media, users frequently rely on
organizing themselves around specific topics of interest to find and engage
with like-minded people. However, navigating these massive worlds and finding
topics of specific interest often proves difficult because the worlds are
mostly organized haphazardly, leaving users to find relevant interests by word
of mouth or using a basic search feature. Here, we report on a method using the
backbone of a network to create a map of the primary topics of interest in any
social network. To demonstrate the method, we build an interest map for the
social news web site reddit and show how such a map could be used to navigate a
social media world. Moreover, we analyze the network properties of the reddit
social network and find that it has a scale-free, small-world, and modular
community structure, much like other online social networks such as Facebook
and Twitter. We suggest that the integration of interest maps into popular
social media platforms will assist users in organizing themselves into more
specific interest groups, which will help alleviate the overcrowding effect
often observed in large online communities.


title: Online Bayesian Passive-Aggressive Learning

abstract:
  Online Passive-Aggressive (PA) learning is an effective framework for
performing max-margin online learning. But the deterministic formulation and
estimated single large-margin model could limit its capability in discovering
descriptive structures underlying complex data. This pa- per presents online
Bayesian Passive-Aggressive (BayesPA) learning, which subsumes the online PA
and extends naturally to incorporate latent variables and perform nonparametric
Bayesian inference, thus providing great flexibility for explorative analysis.
We apply BayesPA to topic modeling and derive efficient online learning
algorithms for max-margin topic models. We further develop nonparametric
methods to resolve the number of topics. Experimental results on real datasets
show that our approaches significantly improve time efficiency while
maintaining comparable results with the batch counterparts.


title: Matrix Product Codes over Finite Commutative Frobenius Rings

abstract:
  Properties of matrix product codes over finite commutative Frobenius rings
are investigated. The minimum distance of matrix product codes constructed with
several types of matrices is bounded in different ways. The duals of matrix
product codes are also explicitly described in terms of matrix product codes.


title:
Pocket doping method on Improving the Performance of Graphene
  Nanoribbons Tunneling FET

abstract:
  A tunneling field effect transistor based on armchair graphene nanoribbons is
studied using ballistic quantum transport simulation based on 3D real space
nonequilibrium Green's function formalism. By introducing a pocket doping
region near the source, the performance of GNRs TFET is improved in terms of
larger on current and steeper subthreshold swings compared to conventional
tunneling FET. It is also found that pocket region introduces two interesting
features. By increasing the pocket length the ambipolar can be effectively
suppressed. Furthermore, there is negative trans-conductance at negative gate
voltage due to resonance.


title:
Improved Performance of Tunneling FET Based on Hetero Graphene
  Nanoribbons

abstract:
  A heterojunction tunneling field effect transistor based on armchair graphene
nanoribbons is proposed and studied using ballistic quantum transport
simulation based on 3D real space nonequilibrium Green's function formalism. By
using low band gap nanoribbons as the source/drain material, the hetero-
structure shows better performance including higher on current, lower off
current, and improved steep subthreshold swings compared with homostructure. It
is also found the device performance greatly depends on the source/drain
dopping density. High doping density leads to fewer density states in the
source and degrades the device performance.


title:
Manipulation of p-wave scattering of cold atoms in low dimensions using
  the magnetic field vector

abstract:
  It is well-known that the magnetic Feshbach resonances of cold atoms are
sensitive to the magnitude of the external magnetic field. Much less attention
has been paid to the direction of such a field. In this work we calculate the
scattering properties of spin polarized fermionic atoms in reduced dimensions,
near a p-wave Feshbach resonance. Because of spatial anisotropy of the p-wave
interaction, the scattering has nontrivial dependence on both the magnitude and
the direction of the magnetic field. In addition, we identify an inelastic
scattering process which is impossible in the isotropic-interaction model; the
rate of this process depends considerably on the direction of the magnetic
field. Significantly, an EPR entangled pair of identical fermions may be
produced during this inelastic collision. This work opens a new method to
manipulate resonant cold atomic interactions.


title: Relative Upper Confidence Bound for the K-Armed Dueling Bandit Problem

abstract:
  This paper proposes a new method for the K-armed dueling bandit problem, a
variation on the regular K-armed bandit problem that offers only relative
feedback about pairs of arms. Our approach extends the Upper Confidence Bound
algorithm to the relative setting by using estimates of the pairwise
probabilities to select a promising arm and applying Upper Confidence Bound
with the winner as a benchmark. We prove a finite-time regret bound of order
O(log t). In addition, our empirical results using real data from an
information retrieval application show that it greatly outperforms the state of
the art.


title: Voting Power of Teams Working Together

abstract:
  Voting power determines the "power" of individuals who cast votes; their
power is based on their ability to influence the winning-ness of a coalition.
Usually each individual acts alone, casting either all or none of their votes
and is equally likely to do either. This paper extends this standard "random
voting" model to allow probabilistic voting, partial voting, and correlated
team voting. We extend the standard Banzhaf metric to account for these cases;
our generalization reduces to the standard metric under "random voting", This
new paradigm allows us to answer questions such as "In the 2013 US Senate, how
much more unified would the Republicans have to be in order to have the same
power as the Democrats in attaining cloture?"


title: Local PT symmetry violates the no-signaling principle

abstract:
  Bender et al. have developed PT-symmetric quantum theory as an extension of
quantum theory to non-Hermitian Hamiltonians. We show that when this model has
a local PT symmetry acting on composite systems it violates the non-signaling
principle of relativity. Since the case of global PT symmetry is known to
reduce to standard quantum mechanics, this shows that the PT-symmetric theory
is either a trivial extension or likely false as a fundamental theory.


title: Non-jumping Numbers for 5-Uniform Hypergraphs

abstract:
  Let $\ell$ and $r$ be integers. A real number $\alpha \in [0,1)$ is a jump
for $r$ if for any $\varepsilon > 0$ and any integer $m,\ m \geq r$, any
$r$-uniform graph with $n > n_0(\varepsilon,m)$ vertices and at least \alpha+
\varepsilon)\binom{n}{r}$ edges contains a subgraph with $m$ vertices and at
least $(\alpha +c)\binom{m}{r}$ edges, where $c=c(\alpha)$ does not depend on
$\varepsilon$ and $m$. It follows from a theorem of Erd\H{o}s, Stone and
Simonovits that every $\alpha \in [0,1)$ is a jump for $r=2$. Erd\H{o}s asked
whether the same is true for $r \geq 3$. However, Frankl and R\"{o}dl gave a
negative answer by showing that $1-\frac{1}{\ell^{r-1}}$ is not a jump for $r$
if $r \geq 3$ and $\ell >2r$. Peng gave more sequences of non-jumping numbers
for $r=4$ and $r\geq 3$. However, there are also a lot of unknowns on
determining whether a number is a jump for $r \geq 3$. Following a similar
approach as that of Frankl and R\"{o}dl, we give several sequences of
non-jumping numbers for $r=5$, and extend one of the results to every $r \geq
5$, which generalize the above results.


title:
The Rogue Waves with Quintic Nonlinearity and Nonlinear Dispersion
  effects in Nonlinear Optical Fibers

abstract:
  We present exact rational solution for a modified nonlinear
Schr$\ddot{o}$dinger equation that takes into account quintic nonlinearity and
nonlinear dispersion corrections to the cubic nonlinearity, which could be used
to describe rogue wave in nonlinear fibers. We find the rogue wave with these
higher order effects has identical shape with the well-known one in nonlinear
Schr$\ddot{o}$dinger equation. However, the quintic nonlinear term and
nonlinear dispersion effect affect the velocity of rogue wave, and the
evolution of its phase.


title: Cluster-Robust Variance Estimation for Dyadic Data

abstract:
  Dyadic data are common in the social sciences, although inference for such
settings involves accounting for a complex clustering structure. Many analyses
in the social sciences fail to account for the fact that multiple dyads share a
member, and that errors are thus likely correlated across these dyads. We
propose a nonparametric sandwich-type robust variance estimator for linear
regression to account for such clustering in dyadic data. We enumerate
conditions for estimator consistency. We also extend our results to repeated
and weighted observations, including directed dyads and longitudinal data, and
provide an implementation for generalized linear models such as logistic
regression. We examine empirical performance with simulations and applications
to international relations and speed dating.


title:
Scalable Safety-Preserving Robust Control Synthesis for Continuous-Time
  Linear Systems

abstract:
  We present a scalable set-valued safety-preserving controller for constrained
continuous-time linear time-invariant (LTI) systems subject to additive,
unknown but bounded disturbance or uncertainty. The approach relies upon a
conservative approximation of the discriminating kernel using robust maximal
reachable sets---an extension of our earlier work on computation of the
viability kernel for high-dimensional systems. Based on ellipsoidal techniques
for reachability, a piecewise ellipsoidal algorithm with polynomial complexity
is described that under-approximates the discriminating kernel under LTI
dynamics. This precomputed piecewise ellipsoidal set is then used online to
synthesize a permissive state-feedback safety-preserving controller. The
controller is modeled as a hybrid automaton and can be formulated such that
under certain conditions the resulting control signal is continuous across its
transitions. We show the performance of the controller on a twelve-dimensional
flight envelope protection problem for a quadrotor with actuation saturation
and unknown wind disturbances.


title:
Solitary waves in Parity-time (PT) symmetric Bragg-grating structure and
  the existence of Optical Rogue Waves

abstract:
  In this work, we have studied the traveling wave solution in a nonlinear
Bragg grating structure in which the core of the optical fiber is having
Parity-time (PT) symmetric refractive index distribution. We have found bright
solitary wave solution below the PT-threshold for forward wave and dark
solitary wave solution above the PT-threshold for backward wave. The effects of
increasing the traveling wave speed on the spatio-temporal evolutions of the
analytical solutions have been shown and the emergence of the Optical Rogue
Waves (ORWs) has been explored based on the system parameters.


title: Parameters Tied to Treewidth

abstract:
  Treewidth is a graph parameter of fundamental importance to algorithmic and
structural graph theory. This paper surveys several graph parameters tied to
treewidth, including separation number, tangle number, well-linked number and
Cartesian tree product number. We review many results in the literature showing
these parameters are tied to treewidth. In a number of cases we also improve
known bounds, provide simpler proofs and show that the inequalities presented
are tight.


title: Periodic Array of Bose-Einstein condensates in a Magnetic Lattice

abstract:
  We report the realization of a periodic array of Bose-Einstein condensates of
87Rb |F = 1; mF = -1> atoms trapped in a one-dimensional magnetic lattice close
(8 micrometres) to the surface of an atom chip. A clear signature for the onset
of BEC in the magnetic lattice is provided by in-situ site-resolved
radiofrequency (RF) spectra, which exhibit a pronounced bimodal distribution
consisting of a narrow component characteristic of a BEC together with a broad
thermal cloud component. Similar bimodal distributions are found for various
sites across the magnetic lattice. The realization of a periodic array of
multiple BECs in a magnetic lattice represents a major advance towards the
implementation of magnetic lattices to simulate many-body condensed matter
phenomena in lattices of complex geometry and arbitrary period.


title:
Neutrino masses and mixing within a SU(3) family symmetry model with one
  or two light sterile neutrinos

abstract:
  We report a global fit of parameters for fermion masses and mixing, including
light sterile neutrinos, within a local vector $SU(3)$ family symmetry model.
In this scenario, ordinary heavy fermions, top and bottom quarks and tau
lepton, become massive at tree level from {\bf Dirac See-saw} mechanisms
implemented by the introduction of a new set of $SU(2)_L$ weak singlet
vector-like fermions, $U,D,E,N$, with $N$ a sterile neutrino. The $N_{L,R}$
sterile neutrinos allow the implementation of a $8\times 8$ general tree level
See-saw Majorana neutrino mass matrix with four massless eigenvalues. Hence,
light fermions, including light neutrinos obtain masses from one loop radiative
corrections mediated by the massive $SU(3)$ gauge bosons. This BSM model is
able to accommodate the known spectrum of quark masses and mixing in a $4\times
4$ non-unitary $V_{CKM}$ as well as the charged lepton masses. The explored
parameter space region provide the vector-like fermion masses: $M_D \approx
914.365 $GeV, $M_U \approx 1.5 $TeV, $M_E \approx 5.97 $TeV, $SU(3)$ family
gauge boson masses of $\mathcal{O} (1-10) $TeV, the neutrino masses $(m_1, m_2,
m_3, m_4, m_5, m_6, m_7, m_8)= (0,0.0085, 0.049, 0.22, 3.21 , 1749.96,1\times
10^8, 1\times 10^9 ) $eV, with the squared neutrino mass differences:
$m_2^2-m_1^2 \approx 7.23 \times 10^{-5} \text{eV}^2$, $m_3^2-m_1^2 \approx 2.4
\times 10^{-3} \text{eV}^2$, $m_4^2-m_1^2 \approx 0.049 \text{eV}^2$,
$m_5^2-m_1^2 \approx 10.3 \text{eV}^2$. We also show the corresponding
$U_{PMNS}$ lepton mixing matrix. However, the neutrino mixing angles are
extremely sensitive to parameter space region, and an improved and detailed
analysis is in progress.


title: Goldstone and Higgs modes of photons inside a cavity

abstract:
  Goldstone and Higgs modes have been detected in various condensed matter,
cold atom and particle physics experiments. Here, we demonstrate that the two
modes can also be observed in optical systems with only a few (artificial)
atoms inside a cavity. We establish this connection by studying the $ U(1)/Z_2
$ Dicke model where $ N $ qubits (atoms) coupled to a single photon mode. We
determine the Goldstone and Higgs modes inside the super-radiant phase and
their corresponding spectral weights by performing both $ 1/J=2/N $ expansion
and exact diagonization (ED) study at a finite $ N $. We find nearly perfect
agreements between the results achieved by the two approaches when $ N $ gets
down even to $ N = 2 $. The quantum finite size effects at a few qubits make
the two modes quite robust against an effectively small counter-rotating wave
term. We present a few schemes to reduce the critical coupling strength, so the
two modes can be observed in several experimental systems of (artificial) atoms
inside a cavity by just conventional optical measurements.

categories: quant-ph cond-mat.str-el physics.atom-ph physics.optics


title: On LiF:Mg,Cu,P and LiF:Mg,Ti phosphors high & ultra-high dose features

abstract:
  LiF:Mg,Ti and LiF:Mg,Cu,P are well known thermoluminescence (TL) dosimetry
materials since many years. A few years ago their properties seemed well known
and it was widely believed that they are not suitable for the measurement of
doses above the saturation level of the TL signal, which for both materials
occur at about 1 kGy. The high-dose high-temperature TL emission of LiF:Mg,Cu,P
observed at the IFJ in 2006, which above 30 kGy takes the form of the so-called
TL peak B, opened the way to use this material for measuring the dose in the
high and ultra-high range, in particular for the monitoring of ionizing
radiation around the essential electronic elements of high-energy accelerators,
also fission and fusion facilities, as well as for emergency dosimetry. This
discovery initiated studies of high and ultra-high dose characteristics of both
of these phosphors, which turned out to be significantly different in many
aspects. These studies not only strive to refine the method for measuring high
doses based on the observed phenomenon, but also, and perhaps above all, bring
us closer to understanding its origin and essence. This manuscript aims to
review existing research data on the high and ultra-high dose features of both
LiF based phosphors.


title: Dependence of nucleon mass on parameters of instanton medium

abstract:
  We trace the dependence of the nucleon mass and of the effective size of the
nucleon on the characteristics of the instanton medium, which are the average
instanton size $\rho$ and the distance between the instantons in instanton
medium R. We consider several scenario for variation of the values of $\rho$
and R.


title: Physical and Structural Design of Fast Extraction Kickers for CSNS/RCS

abstract:
  China Spallation Neutron Source (CSNS) is a high intensity beam facility
being built now in China. Three kicker assemblies, eight pulsed magnets, will
be used in the CSNS rapid circle synchrotron (RCS). The physical and structural
designs of eight kicker magnets that are grouped in 5 different types are
presented. The results of OPERA-3D simulation show that magnet center field
integral meet the physics requirements of design by choosing a suitable magnet
coil structure. Field uniformity for 60% width is +/-0.7%. The ferrite magnet
structure and composition is introduced, and the high voltage feedthrough
design, the installation of six magnets in long vacuum cavity design is
discussed.


title: The irregularities of the sunspot cycle and their theoretical modelling

abstract:
  The 11-year sunspot cycle has many irregularities, the most promi- nent
amongst them being the grand minima when sunspots may not be seen for several
cycles. After summarizing the relevant observational data about the
irregularities, we introduce the flux transport dynamo model, the currently
most successful theoretical model for explaining the 11-year sunspot cycle.
Then we analyze the respective roles of nonlinearities and random fluctuations
in creating the irregularities. We also discuss how it has recently been
realized that the fluctuations in meridional circula- tion also can be a source
of irregularities. We end by pointing out that fluctuations in the poloidal
field generation and fluctuations in meridional circulation together can
explain the occurrences of grand minima.


title: Modal Decomposition in Goalpost Micro/nano Electro-mechanical Devices

abstract:
  We have studied the first three symmetric out-of-plane flexural resonance
modes of a goalpost silicon micro-mechanical device. Measurements have been
performed at 4.2K in vacuum, demonstrating high Qs and good linear properties.
Numerical simulations have been realized to fit the resonance frequencies and
produce the mode shapes. These mode shapes are complex, since they involve
distortions of two coupled orthogonal bars. Nonetheless, analytic expressions
have been developed to reproduce these numerical results, with no free
parameters. Owing to their generality they are extremely helpful, in particular
to identify the parameters which may limit the performances of the device. The
overall agreement is very good, and has been verified on our nano-mechanical
version of the device.


title: Cosmological singularities in Bakry-\'Emery spacetimes

abstract:
  We consider spacetimes consisting of a manifold with Lorentzian metric and a
weight function or scalar field. These spacetimes admit a Bakry-\'Emery-Ricci
tensor which is a natural generalization of the Ricci tensor. We impose an
energy condition on the Bakry-\'Emery-Ricci tensor and obtain singularity
theorems of a cosmological type, both for zero and for positive cosmological
constant. That is, we find conditions under which every timelike geodesic is
incomplete. These conditions are given by "open" inequalities, so we examine
the borderline (equality) cases and show that certain singularities are avoided
in these cases only if the geometry is rigid; i.e., if it splits as a
Lorentzian product or, for a positive cosmological constant, a warped product,
and the weight function is constant along the time direction. Then the product
case is future timelike geodesically complete while, in the warped product
case, worldlines of certain conformally static observers are complete. Our
results answer a question posed by J Case. We then apply our results to the
cosmology of scalar-tensor gravitation theories. We focus on the Brans-Dicke
family of theories in 4 spacetime dimensions, where we obtain "Jordan frame"
singularity theorems for big bang singularities.


title: Relative Garside elements of Artin monoids

abstract:
  We introduce a relative Garside element, the quotient of the corresponding
Garside elements G1 and G2, for a pair of Artin monoids associated to Coxeter
graphs Gamma1 and Gamma2, the second graph containing a new vertex. These
relative elements give a recurrence relation between Garside elements. As an
application, we compute explicitly the Garside elements of Artin monoids
corresponding to spherical Coxeter graphs or the longest elements of the
associated finite Coxeter groups.


title: The Determinacy of Context-Free Games

abstract:
  We prove that the determinacy of Gale-Stewart games whose winning sets are
accepted by real-time 1-counter B\"uchi automata is equivalent to the
determinacy of (effective) analytic Gale-Stewart games which is known to be a
large cardinal assumption. We show also that the determinacy of Wadge games
between two players in charge of omega-languages accepted by 1-counter B\"uchi
automata is equivalent to the (effective) analytic Wadge determinacy. Using
some results of set theory we prove that one can effectively construct a
1-counter B\"uchi automaton A and a B\"uchi automaton B such that: (1) There
exists a model of ZFC in which Player 2 has a winning strategy in the Wadge
game W(L(A), L(B)); (2) There exists a model of ZFC in which the Wadge game
W(L(A), L(B)) is not determined. Moreover these are the only two possibilities,
i.e. there are no models of ZFC in which Player 1 has a winning strategy in the
Wadge game W(L(A), L(B)).


title: A region of high-spin toroidal isomers

abstract:
  The combined considerations of both the bulk liquid-drop-type behawior and
the quantized angular momentum reveal that high-spin toroidal isomeric states
may have general occurrences for light nuclei with 28 <= A <= 48. High-spin N=Z
toroidal isomers in this mass region have been located theoretically using
cranked self-consistent constraint Skyrme-Hartree-Fock model calculations.


title: On Uncertainty of Compton Backscattering Process

abstract:
  The uncertainty of Compton backscattering process is studied by virtue of
analytical formulas, and the special effects of variant energy spread and
energy drift on the systematic uncertainty estimation are also studied with
Monte Carlo sampling technique. These quantitative conclusions are especially
important for the understanding the uncertainty of beam energy measurement
system.


title:
Testing Local Anisotropy Using the Method of Smoothed Residuals I -
  Methodology

abstract:
  We discuss some details regarding the method of smoothed residuals, which has
recently been used to search for anisotropic signals in low-redshift distance
measurements (Supernovae). In this short note we focus on some details
regarding the implementation of the method, particularly the issue of
effectively detecting signals in data that are inhomogeneously distributed on
the sky. Using simulated data, we argue that the original method proposed in
Colin et al. [1] will not detect spurious signals due to incomplete sky
coverage, and that introducing additional Gaussian weighting to the statistic
as in [2] can hinder its ability to detect a signal. Issues related to the
width of the Gaussian smoothing are also discussed.


title: On-the-fly Fast Mean-Field Model-Checking: Extended Version

abstract:
  A novel, scalable, on-the-fly model-checking procedure is presented to verify
bounded PCTL properties of selected individuals in the context of very large
systems of independent interacting objects. The proposed procedure combines
on-the-fly model checking techniques with deterministic mean-field
approximation in discrete time. The asymptotic correctness of the procedure is
shown and some results of the application of a prototype implementation of the
FlyFast model-checker are presented.


title: Asymptotic MMSE Analysis Under Sparse Representation Modeling

abstract:
  Compressed sensing is a signal processing technique in which data is acquired
directly in a compressed form. There are two modeling approaches that can be
considered: the worst-case (Hamming) approach and a statistical mechanism, in
which the signals are modeled as random processes rather than as individual
sequences. In this paper, the second approach is studied. In particular, we
consider a model of the form $\boldsymbol{Y} =
\boldsymbol{H}\boldsymbol{X}+\boldsymbol{W}$, where each comportment of
$\boldsymbol{X}$ is given by $X_i = S_iU_i$, where $\left\{U_i\right\}$ are
i.i.d. Gaussian random variables, and $\left\{S_i\right\}$ are binary random
variables independent of $\left\{U_i\right\}$, and not necessarily independent
and identically distributed (i.i.d.), $\boldsymbol{H}\in\mathbb{R}^{k\times n}$
is a random matrix with i.i.d. entries, and $\boldsymbol{W}$ is white Gaussian
noise. Using a direct relationship between optimum estimation and certain
partition functions, and by invoking methods from statistical mechanics and
from random matrix theory (RMT), we derive an asymptotic formula for the
minimum mean-square error (MMSE) of estimating the input vector
$\boldsymbol{X}$ given $\boldsymbol{Y}$ and $\boldsymbol{H}$, as
$k,n\to\infty$, keeping the measurement rate, $R = k/n$, fixed. In contrast to
previous derivations, which are based on the replica method, the analysis
carried out in this paper is rigorous.


title: One-Bit Compressed Sensing by Greedy Algorithms

abstract:
  Sign truncated matching pursuit (STrMP) algorithm is presented in this paper.
STrMP is a new greedy algorithm for the recovery of sparse signals from the
sign measurement, which combines the principle of consistent reconstruction
with orthogonal matching pursuit (OMP). The main part of STrMP is as concise as
OMP and hence STrMP is simple to implement. In contrast to previous greedy
algorithms for one-bit compressed sensing, STrMP only need to solve a convex
and unconstraint subproblem at each iteration. Numerical experiments show that
STrMP is fast and accurate for one-bit compressed sensing compared with other
algorithms.


title:
A strontium lattice clock with $3 \times 10^{-17}$ inaccuracy and its
  frequency

abstract:
  We have measured the absolute frequency of the optical lattice clock based on
$^{87}$Sr at PTB with an uncertainty of $3.9\times 10^{-16}$ using two caesium
fountain clocks. This is close to the accuracy of today's best realizations of
the SI second. The absolute frequency of the 5s$^2$ $^1$S$_0$-5s5p $^3$P$_0$
transition in $^{87}$Sr is 429,228,004,229,873.13(17) Hz. Our result is in
excellent agreement with recent measurements performed in different
laboratories worldwide. We improved the total systematic uncertainty of our Sr
frequency standard by a factor of five and reach $3\times 10^{-17}$, opening
new prospects for frequency ratio measurements between optical clocks for
fundamental research, geodesy, or optical clock evaluation.


title: Group Key Agreement Protocol for MANETs Based on HSK Scheme

abstract:
  In this paper, we first provide a spanning tree (ST)-based centralized group
key agreement protocol for unbalanced mobile Ad Hoc networks (MANETs). Based on
the centralized solution, a local spanning tree (LST)-based distributed
protocol for general MANETs is subsequently presented. Both protocols follow
the basic features of the HSK scheme: 1) H means that a hybrid approach, which
is the combination of key agreement and key distribution via symmetric
encryption, is exploited; 2) S indicates that a ST or LSTs are adopted to form
a connected network topology; and 3) K implies that the extended Kruskal
algorithm is employed to handle dynamic events. It is shown that the HSK scheme
is a uniform approach to handle the initial key establishment process as well
as all kinds of dynamic events in group key agreement protocol for MANETs.
Additionally, the extended Kruskal algorithm enables to realize the reusability
of the precomputed secure links to reduce the overhead. Moreover, some other
aspects, such as the network topology connectivity and security, are well
analyzed.


title: Thompson's group F is not SCY

abstract:
  In this note we prove that Thompson's group F cannot be the fundamental group
of a symplectic 4-manifold with trivial canonical class by showing that its
Hausmann-Weinberger invariant q(F) is strictly positive.


title: Compressed Spaced Suffix Arrays

abstract:
  Spaced seeds are important tools for similarity search in bioinformatics, and
using several seeds together often significantly improves their performance.
With existing approaches, however, for each seed we keep a separate linear-size
data structure, either a hash table or a spaced suffix array (SSA). In this
paper we show how to compress SSAs relative to normal suffix arrays (SAs) and
still support fast random access to them. We first prove a theoretical upper
bound on the space needed to store an SSA when we already have the SA. We then
present experiments indicating that our approach works even better in practice.


title: 2-connected equimatchable graphs on surfaces

abstract:
  A graph $G$ is equimatchable if any matching in $G$ is a subset of a
maximum-size matching. It is known that any $2$-connected equimatchable graph
is either bipartite or factor-critical. We prove that for any vertex $v$ of a
$2$-connected factor-critical equimatchable graph $G$ and a minimal matching
$M$ that isolates $v$ the graph $G\setminus(M\cup\{ v\})$ is either $K_{2n}$ or
$K_{n,n}$ for some $n$. We use this result to improve the upper bounds on the
maximum size of $2$-connected equimatchable factor-critical graphs embeddable
in the orientable surface of genus $g$ to $4\sqrt g+17$ if $g\le 2$ and to
$12\sqrt g+5$ if $g\ge 3$. Moreover, for any nonnegative integer $g$ we
construct a $2$-connected equimatchable factor-critical graph with genus $g$
and more than $4\sqrt{2g}$ vertices, which establishes that the maximum size of
such graphs is $\Theta(\sqrt g)$. Similar bounds are obtained also for
nonorientable surfaces. Finally, for any nonnegative integers $g$, $h$ and $k$
we provide a construction of arbitrarily large $2$-connected equimatchable
bipartite graphs with orientable genus $g$, respectively nonorientable genus
$h$, and a genus embedding with face-width $k$.


title: 3D Galactic dust extinction mapping with multi-band photometry

abstract:
  We present a method to simultaneously infer the interstellar extinction
parameters $A_0$ and $R_0$, stellar effective temperature $T_{\rm eff}$, and
distance modulus $\mu$ in a Bayesian framework. Using multi-band photometry
from SDSS and UKIDSS, we train a forward model to emulate the colour-change due
to physical properties of stars and the interstellar medium for temperatures
from 4000 to 9000 K and extinctions from 0 to 5 mag. We introduce a
Hertzsprung-Russel diagram prior to account for physical constraints on the
distribution of stars in the temperature-absolute magnitude plane. This allows
us to infer distances probabilistically. Influences of colour information,
priors and model parameters are explored. Residual mean absolute errors (MAEs)
on a set of objects for extinction and temperature are 0.2 mag and 300 K,
respectively, for $R_0$ fixed to 3.1. For variable $R_0$, we obtain MAEs of
0.37 mag, 412.9 K and 0.74 for $A_0$, $T_{\rm eff}$ and $R_0$, respectively.
Distance moduli are accurate to approximately 2 mag. Quantifying the precisions
of individual parameter estimates with $68\%$ confidence interval of the
posterior distribution, we obtain 0.05 mag, 66 K, 2 mag and 0.07 for $A_0$,
$T_{\rm eff}$, $\mu$ and $R_0$, respectively, although we find that these
underestimate the accuracy of the model. We produce two-dimensional maps in
extinction and $R_0$ that are compared to previous work. Furthermore we
incorporate the inferred distance information to compute fully probabilistic
distance profiles for individual lines of sight. The individual stellar AP
estimates, combined with inferred 3D information will make possible many
Galactic science and modelling applications. Adapting our method to work with
other surveys, such as Pan-STARRS and Gaia, will allow us to probe other
regions of the Galaxy.


title:
Continuous Transitions between Discontinuous Magnetohydrodynamic Flows
  of Plasma and Its Heating

abstract:
  The possibility that the type of discontinuous flow changes as the conditions
gradually (continuously) change is investigated in connection with the problems
arising when the results of numerical simulations of magnetic reconnection in
plasma are interpreted. The conservation laws at a discontinuity surface in
magnetohydrodynamics admit such transitions, but the socalled transition
solutions for the boundary conditions that simultaneously satisfy two types of
discontinuities should exist in this case. The specific form of such solutions
has been found, and a generalized scheme of permitted transitions has been
constructed on their basis. An expression for the jump in internal energy at
discontinuity is derived. The dependence of the plasma heating efficiency on
the type of discontinuity is considered.


title: An ESPResSo implementation of elastic objects immersed in a fluid

abstract:
  We review the lattice-Boltzmann (LB) method coupled with the immersed
boundary (IB) method for the description of combined flow of particulate
suspensions with immersed elastic objects. We describe the implementation of
the combined LB-IB method into the open-source package ESPResSo. We present
easy-to-use structures used to model a closed object in a simulation package,
the definition of its elastic properties, and the interaction between the fluid
and the immersed object. We also present the test cases with short examples of
the code explaining the functionality of the new package.

categories: physics.comp-ph math-ph math.MP physics.flu-dyn


title: The Emergent Copenhagen Interpretation of Quantum Mechanics

abstract:
  We introduce a new and conceptually simple interpretation of quantum
mechanics based on reduced density matrices of sub-systems from which the
standard Copenhagen interpretation emerges as an effective description of
macroscopically large systems. Wave function collapse is seen to be a useful
but fundamentally unnecessary piece of prudent book keeping which is only valid
for macro-systems. The new interpretation lies in a class of modal
interpretations in that it applies to quantum systems that interact with a much
larger environment. However, we show that it does not suffer from the problems
that have plagued similar modal interpretations like macroscopic superpositions
and rapid flipping between macroscopically distinct states. We describe how the
interpretation fits neatly together with fully quantum formulations of
statistical mechanics and that a measurement process can be viewed as a process
of ergodicity breaking analogous to a phase transition. The key feature of the
new interpretation is that joint probabilities for the ergodic subsets of
states of disjoint macro-systems only arise as emergent quantities. Finally we
give an account of the EPR-Bohm thought experiment and show that the
interpretation implies the violation of the Bell inequality characteristic of
quantum mechanics but in a way that is rather novel. The final conclusion is
that the Copenhagen interpretation gives a completely satisfactory
phenomenology of macro-systems interacting with micro-systems.


title: Toric ideals of series and parallel connections of matroids

abstract:
  In 1980, White conjectured that the toric ideal associated to a matroid is
generated by binomials corresponding to a symmetric exchange. In this paper, we
prove that classes of matroids for which the toric ideal is generated by
quadrics and that has quadratic Gr\"obner bases, are closed under series and
parallel extensions, series and parallel connections, and 2-sums.


title: Unsupervised learning of depth and motion

abstract:
  We present a model for the joint estimation of disparity and motion. The
model is based on learning about the interrelations between images from
multiple cameras, multiple frames in a video, or the combination of both. We
show that learning depth and motion cues, as well as their combinations, from
data is possible within a single type of architecture and a single type of
learning algorithm, by using biologically inspired "complex cell" like units,
which encode correlations between the pixels across image pairs. Our
experimental results show that the learning of depth and motion makes it
possible to achieve state-of-the-art performance in 3-D activity analysis, and
to outperform existing hand-engineered 3-D motion features by a very large
margin.


title: Simplicity of the automorphism groups of some Hrushovski constructions

abstract:
  We show that the automorphism groups of certain countable structures obtained
using the Hrushovski amalgamation method are simple groups. The structures we
consider are the 'uncollapsed' structures of infinite Morley rank obtained by
the ab initio construction and the (unstable) omega-categorical pseudoplanes.
The simplicity of the automorphism groups of these follows from results which
generalize work of Lascar and of Tent and Ziegler.


title:
The Behavior of the Free Boundary for Reaction-Diffusion Equations with
  Convection in an Exterior Domain with Neumann or Dirichlet Boundary Condition

abstract:
  Let \begin{equation*} L=\sum_{i,j=1}^da_{i,j}\frac{\partial^2}{\partial
x_i\partial x_j}-\sum_{i=1}^db_i\frac{\partial}{\partial x_i} \end{equation*}
be a second order elliptic operator and consider the reaction-diffusion
equation with Neumann boundary condition, \begin{equation*} \begin{aligned}
&Lu=\Lambda u^p\ \text{in}\ \mathbb{R}^d-D;\\ &\nabla u\cdot \bar n=-h\
\text{on}\ \partial D;\\ &u\ge0 \ \text{is minimal}, \end{aligned}
\end{equation*} where $p\in(0,1)$, $d\ge2$, $h$ and $\Lambda$ are continuous
positive functions, $D\subset R^d$ is bounded, and $\bar n$ is the unit inward
normal to the domain $\mathbb{R}^d-\bar D$. Consider also the same equations
with the Neumann boundary condition replaced by the Dirichlet boundary
condition; namely, $u=h$ on $\partial D$. The solutions to the above equations
may possess a free boundary. When $D=\{|x|<R\}$ and $L$ and $\Lambda$ are
radially symmetric, we write the solution as $u(r)$ with $r=|x|$ and define the
radius of the free boundary by $r^*(h)=\inf\{r>R:u(r)=0\}$. We normalize the
diffusion coefficient to be on unit order, consider the convection vector field
to be on order $r^m$, $m\in R$, pointing either inward $(-)$ or outward $(+)$,
and consider the reaction coefficient $\Lambda$ to be on order $r^{-j}$, $j\in
R$. For both the Neumann boundary case and the Dirichlet boundary case, we show
for which choices of $m$, $(\pm)$ and $j$ a free boundary exists, and when it
exists, we obtain its growth rate in $h$ as a function of $m$, $(\pm)$ and $j$.
These results are then used to study the free boundary in the non-radially
symmetric case.


title:
Universal bound independent of geometry for solution to symmetric
  diffusion equation in exterior domain with boundary flux

abstract:
  Fix $R>0$ and let $B_R$ denote the ball of radius $R$ centered at the origin
in $R^d$, $d\ge2$. Let $D\subset B_R$ be an open set with smooth boundary and
such that $R^d-\bar D$ is connected, and let $$
L=\sum_{i,j=1}^da_{i,j}\frac{\partial^2}{\partial x_i\partial
x_j}-\sum_{i=1}^db_i\frac{\partial}{\partial x_i} $$ be a second order elliptic
operator. Consider the following linear heat equation in the exterior domain
$R^d-\bar D$ with boundary flux: \begin{equation*} \begin{aligned} &L u=0 \
\text{in}\ R^d-\bar D;\\ &a\nabla u\cdot \bar n=-h\ \text{on}\ \partial D;\\
&u>0 \ \text{is minimal}, \end{aligned} \end{equation*} where $h\gneq0$ is
continuous, and where $\bar n$ is the unit inward normal to the domain
$R^d-\bar D$. The operator $L$ must possess a Green's function in order that a
solution $u$ exist. An important feature of the equation is that there is no a
priori bound on the supremum $\sup_{x\in R^d-\bar D}u(x)$ of the solution
exclusively in terms of the boundary flux $h$, the hyper-surface measure of
$\partial D$ and the coefficients of $L$; rather the geometry of $D\subset B_R$
plays an essential role. However, we prove that in the case that $L$ is a \it
symmetric operator\rm\ with respect to some reference measure, then \it outside
of\rm\ $\bar B_R$, the solution to \eqref{LHE} is uniformly bounded,
independent of the particular choice of $D\subset B_R$. The proof uses a
combination of analytic and probabilistic techniques.


title: Analogues of Lusztig's higher order relations for the q-Onsager algebra

abstract:
  Let $A,A^*$ be the generators of the $q-$Onsager algebra. Analogues of
Lusztig's $r-th$ higher order relations are proposed. In a first part, based on
the properties of tridiagonal pairs of $q-$Racah type which satisfy the
defining relations of the $q-$Onsager algebra, higher order relations are
derived for $r$ generic. The coefficients entering in the relations are
determined from a two-variable polynomial generating function. In a second
part, it is conjectured that $A,A^*$ satisfy the higher order relations
previously obtained. The conjecture is proven for $r=2,3$. For $r$ generic,
using an inductive argument recursive formulae for the coefficients are
derived. The conjecture is checked for several values of $r\geq 4$.
Consequences for coideal subalgebras and integrable systems with boundaries at
$q$ a root of unity are pointed out.

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


title:
Multifractality due to long-range correlation in the L-band ionospheric
  scintillation S4 index time series

abstract:
  The earth's ionosphere is well recognized as a dynamical system and
non-linearly coupled with the magnetosphere above and natural atmosphere
below.The shape and time variability of the ionosphere indeed shows chaos,
pattern formation, random behavior and self-organization. The present paper
studies the propriety of Multifractal Detrended Fluctuation Analysis (MF-DFA)
technique for the ionospheric scintillation index time series. MF-DFA is used
to identify the scaling behavior of the ionospheric scintillation time-series
data of two different nature.The obtained results show the robustness and the
relevancy of the MF-DFA technique for the ionospheric scintillation index time
series. The comparison of the MF-DFA results of original data to those of
shuffled and surrogate series shows that the multifractal nature of considered
time series is almost due to long-range correlations. Subsequently, the Hurst
exponents derived from two parallel methods namely Re-scaled range analysis
(R/S) and Auto Correlation Function (ACF) are also suggesting the presence of
long range correlation. The presented results in this work may be of assistance
for future modeling and simulation studies.


title:
An Approach to the interpretation of spontaneous transitions into a
  state of high conductivity in the PVC composite films

abstract:
  The results of experimental studies of conductivity anomalies in film samples
of specially synthesized copolymer are analyzed, in which in PVC macromolecules
the polyacetylene molecular fragments are embedded with a variable
concentration. Previously, it has been experimentally found that in such
samples spontaneous and stimulated conductivity jumps by 12 orders of magnitude
occur, and the life of each of these states can be very large - minutes, hours
and more. In this paper we propose a qualitative model describing the anomalous
behavior of the conductivity of the PVC composite, comprising the mechanisms of
stabilization of high conductivity state, the conditions of development of
instability in the transitions between the states, as well as the reasons for
long living state of high conductivity even when the applied voltage is
switched off. Simple numerical estimates confirming the reality of the proposed
mechanisms are considered too.


title:
Generalized Darboux transformation and localized waves in coupled Hirota
  equations

abstract:
  In this paper, we construct a generalized Darboux transformation to the
coupled Hirota equations with high-order nonlinear effects like the third
dispersion, self-steepening and inelastic Raman scattering terms. As
application, an Nth-order localized wave solution on the plane backgrounds with
the same spectral parameter is derived through the direct iterative rule. In
particular, some semi-rational, multi-parametric localized wave solutions are
obtained: (1) Vector generalization of the first- and the second-order rogue
wave solution; (2) Interactional solutions between a dark-bright soliton and a
rogue wave, two dark-bright solitons and a second-order rogue wave; (3)
Interactional solutions between a breather and a rogue wave, two breathers and
a second-order rogue wave. The results further reveal the striking dynamic
structures of localized waves in complex coupled systems.


title: On the growth of a Coxeter group

abstract:
  For a Coxeter system $(W,S)$ let $a_n^{(W,S)}$ be the cardinality of the
sphere of radius $n$ in the Cayley graph of $W$ with respect to the standard
generating set $S$. It is shown that, if $(W,S)\preceq(W',S')$ then
$a_n^{(W,S)}\leq a_n^{(W',S')}$ for all $n\in \mathbb{N}_0$, where $\preceq$ is
a suitable partial order on Coxeter systems (cf. Thm. A).
  It is proven that there exists a constant $\tau= 1.13\dots$ such that for any
non-affine, non-spherical Coxeter system $(W,S)$ the growth rate
$\omega(W,S)=\limsup \sqrt[n]{a_n}$ satisfies $\omega(W,S)\geq \tau$ (cf. Thm.
B). The constant $\tau$ is a Perron number of degree $127$ over $\mathbb{Q}$.
  For a Coxeter group $W$ the Coxeter generating set is not unique (up to
$W$-conjugacy), but there is a standard procedure, the diagram twisting (cf.
[BMMN02]), which allows one to pass from one Coxeter generating set $S$ to
another Coxeter generating set $\mu(S)$. A generalisation of the diagram
twisting is introduced, the mutation, and it is proven that Poincar\'e series
are invariant under mutations (cf. Thm. C).


title:
Gibbs-non-Gibbs dynamical transitions for mean-field interacting
  Brownian motions

abstract:
  We consider a system of real-valued spins interacting with each other through
a mean-field Hamiltonian that depends on the empirical magnetization of the
spins via a general potential. The system is subjected to a stochastic dynamics
where the spins perform independent Brownian motions. As in \cite{FedHoMa13},
which considers the Curie-Weiss model with Ising spins interacting via a
quadratic potential and subjected to independent spins flips, we follow the
program outlined in \cite{vEFedHoRe10}. We show that in the thermodynamic limit
the system is non-Gibbs at time $t \in (0,\infty)$ if and only if there exists
an $\alpha \in \mathbb{R}$ such that the large deviation rate function for the
trajectory of the magnetization conditional on hitting the value $\alpha$ at
time $t$ has multiple global minimizers. We further show that different
minimizing trajectories are different at time $t=0$. We give conditions on the
potential under which the system is Gibbs at time $t=0$, classify the possible
scenarios of being Gibbs at time $t \in (0,\infty)$ in terms of the second
difference quotient of the potential, and show that the system cannot become
Gibbs once it has become non-Gibbs, i.e., there is a unique and explicitly
computable crossover time $t_c \in [0,\infty]$ from Gibbs to non-Gibbs. We give
examples of immediate loss of Gibbsianness ($t_c=0$), short-time conservation
of Gibbsianness, large-time loss of Gibbsianness ($t_c\in (0,\infty)$), and
preservation of Gibbsianness ($t_c=\infty$). Depending on the potential, the
system can be Gibbs or non-Gibbs at the cross-over time time $t=t_c$.


title:
Exact results for a generalized spin-1/2 Ising-Heisenberg diamond chain
  with the second-neighbor interaction between nodal spins

abstract:
  The ground state and thermodynamics of a generalized spin-1/2
Ising-Heisenberg diamond chain with the second-neighbor interaction between
nodal spins are calculated exactly using the mapping method based on the
decoration-iteration transformation. Rigorous results for the magnetization,
susceptibility, and heat capacity are investigated in dependence on temperature
and magnetic field for the frustrated diamond spin chain with the
antiferromagnetic Ising and Heisenberg interactions. It is demonstrated that
the second-neighbor interaction between nodal spins gives rise to a greater
diversity of low-temperature magnetization curves, which may include an
intermediate plateau at two-third of the saturation magnetization related to
the classical ferrimagnetic (up-up-up-down-up-up-...) ground state with
translationally broken symmetry besides an intermediate one-third magnetization
plateau reflecting the translationally invariant quantum ferrimagnetic
(monomer-dimer) spin arrangement.


title: Improved stability for odd-dimensional orthogonal group

abstract:
  We compute the kernel of the stabilization map for $K_1$-functors modeled on
split Chevalley groups of types $B_l, C_l, E_l$ one step below the stable
range. For the groups of type $B_l$ this implies early injective stability for
$K_1(B_l, R)$ over a certain class of rings.


title:
Call Me MayBe: Understanding Nature and Risks of Sharing Mobile Numbers
  on Online Social Networks

abstract:
  There is a great concern about the potential for people to leak private
information on OSNs, but few quantitative studies on this. This research
explores the activity of sharing mobile numbers on OSNs, via public profiles
and posts. We attempt to understand the characteristics and risks of mobile
numbers sharing behaviour on OSNs and focus on Indian mobile numbers. We
collected 76,347 unique mobile numbers posted by 85905 users on Twitter and
Facebook and analysed 2997 numbers, prefixed with +91. We observed, most users
shared their own mobile numbers to spread urgent information; and to market
products and escort business. Fewer female users shared mobile numbers on OSNs.
Users utilized other OSN platforms and third party applications like
Twitterfeed, to post mobile numbers on multiple OSNs. In contrast to the user's
perception of numbers spreading quickly on OSN, we observed that except for
emergency, most numbers did not diffuse deep. To assess risks associated with
mobile numbers exposed on OSNs, we used numbers to gain sensitive information
about their owners (e.g. name, Voter ID) by collating publicly available data
from OSNs, Truecaller, OCEAN. On using the numbers on WhatApp, we obtained a
myriad of sensitive details (relationship status, BBM pins) of the number
owner. We communicated the observed risks to the owners by calling. Few users
were surprised to know about the online presence of their number, while a few
others intentionally posted it online for business purposes. We observed, 38.3%
of users who were unaware of the online presence of their number have posted
their number themselves on the social network. With these observations, we
highlight that there is a need to monitor leakage of mobile numbers via profile
and public posts. To the best of our knowledge, this is the first exploratory
study to critically investigate the exposure of Indian mobile numbers on OSNs.


title: Gas-to-Dust mass ratios in local galaxies over a 2 dex metallicity range

abstract:
  This paper analyses the behaviour of the gas-to-dust mass ratio (G/D) of
local Universe galaxies over a large metallicity range. We combine three
samples: the Dwarf Galaxy Survey, the KINGFISH survey and a subsample from
Galametz et al. (2011) totalling 126 galaxies, covering a 2 dex metallicity
range, with 30% of the sample with 12+log(O/H) < 8.0. The dust masses are
homogeneously determined with a semi-empirical dust model, including submm
constraints. The atomic and molecular gas masses are compiled from the
literature. Two XCO are used to estimate molecular gas masses: the Galactic
XCO, and a XCO depending on the metallicity (as Z^{-2}). Correlations with
morphological types, stellar masses, star formation rates and specific star
formation rates are discussed. The trend between G/D and metallicity is
empirically modelled using power-laws (slope of -1 and free) and a broken
power-law. We compare the evolution of the G/D with predictions from chemical
evolution models. We find that out of the five tested galactic parameters,
metallicity is the galactic property driving the observed G/D. The G/D versus
metallicity relation cannot be represented by a power-law with a slope of -1
over the whole metallicity range. The observed trend is steeper for
metallicities lower than ~ 8.0. A large scatter is observed in the G/D for a
given metallicity, with a dispersion of 0.37 dex in metallicity bins of ~0.1
dex. The broken power-law reproduces best the observed G/D and provides
estimates of the G/D that are accurate to a factor of 1.6. The good agreement
of the G/D and its scatter with the three tested chemical evolution models
shows that the scatter is intrinsic to galactic properties, reflecting the
different star formation histories, dust destruction efficiencies, dust grain
size distributions and chemical compositions across the sample. (abriged)


title: Thermo-Galvanometric Instabilities in Magnetized Plasma Disks

abstract:
  In this work, we present a linear stability analysis of fully-ionized
rotating plasma disks with a temperature gradient and a sub-thermal background
magnetic field (oriented towards the axial direction). We describe how the
plasma reacts when galvanometric and thermo-magnetic phenomena, such as Hall
and Nernst-Ettingshausen effects, are taken into account, and meridian
perturbations of the plasma are considered. It is shown how, in the ideal case,
this leads to a significant overlap of the Magneto-rotational Instability and
the Thermo-magnetic one. Considering dissipative effects, an overall damping of
the unstable modes, although not sufficient to fully suppress the instability,
appears especially in the thermo-magnetic related branch of the curve.


title:
Some results of domination and total domination in the direct product of
  two fuzzy graphs

abstract:
  In this article we give a new definition of direct product of two arbitrary
fuzzy graphs. We define the concepts of domination and total domination in this
new product graph. We obtain an upper bound for the total domination number of
the product fuzzy graph. Further we define the concept of total
alpha-domination number and derive a lower bound for the total domination
number of the product fuzzy graph in terms of the total alpha-domination number
of the component graphs. A lower bound for the domination number of the same
has also been found.


title:
Disturbance accelerates the transition from low- to high- diversity
  state in a model ecosystem

abstract:
  The effect of disturbance on a model ecosystem of sessile and mutually
competitive species [Mathiesen et al. Phys. Rev. Lett. 107, 188101 (2011);
Mitarai et al. Phys. Rev. E 86, 011929 (2012) ] is studied. The disturbance
stochastically removes individuals from the system, and the created empty sites
are re-colonized by neighbouring species. We show that the stable
high-diversity state, maintained by occasional cyclic species interactions that
create isolated patches of meta-populations, is robust against small
disturbance. We further demonstrate that finite disturbance can accelerate the
transition from the low- to high-diversity state by helping creation of small
patches through diffusion of boundaries between species with stand-off
relation.


title: Atom-Light Interactions in Photonic Crystals

abstract:
  The integration of nanophotonics and atomic physics has been a long-sought
goal that would open new frontiers for optical physics. Here, we report the
development of the first integrated optical circuit with a photonic crystal
capable of both localizing and interfacing atoms with guided photons in the
device. By aligning the optical bands of a photonic crystal waveguide (PCW)
with selected atomic transitions, our platform provides new opportunities for
novel quantum transport and many-body phenomena by way of photon-mediated
atomic interactions along the PCW. From reflection spectra measured with
average atom number N = 1.1$\pm$0.4, we infer that atoms are localized within
the PCW by Casimir-Polder and optical dipole forces. The fraction of
single-atom radiative decay into the PCW is $\Gamma_{\rm 1D}/\Gamma'$ =
0.32$\pm$0.08, where $\Gamma_{1D}$ is the rate of emission into the guided mode
and $\Gamma'$ is the decay rate into all other channels. $\Gamma_{\rm
1D}/\Gamma'$ is quoted without enhancement due to an external cavity and is
unprecedented in all current atom-photon interfaces.


title:
Evolutionary game theory and the tower of Babel of cooperation:
  Altruism, free-riding, parasitism and the structure of the interactions in a
  world with finite resources

abstract:
  The study of the evolution of cooperative behaviours --which provide benefits
to others-- and altruism --which provides benefits to others at a cost to
oneself-- has been on the core of the evolutionary game theoretical framework
since its foundation. The fast development of the theory during the last years
has improved our knowledge of the issue, but carried attached a diversification
of concepts which affected communication between scientists. Furthermore, the
main root of conflict in the struggle for life identified by Darwin, the
limited amount of resources present in any ecosystem, which is assumed to keep
a constant population size in most game theoretical studies, has only recently
been taken into account as explicitly influencing the evolutionary process.
This review concerns about both issues, the conceptual diversification during
the last years and the new results of the resource dependent models. In
extenso: After a historical introduction, a review of the most important
concepts is carried out. Then it is shown that pairwise interactions and
additive fitness determine prisoner's dilemmas (PDs) or harmony games, that two
altruists interacting together may determine a PD, and that the interaction
environment of the most cooperative and less selfish individual in any
population is always a PD. After that, it is shown that in addition to
altruists versus free-riders, the combination of free-riders and parasites
determines a fundamentally different PD. Computer simulations are then carried
out to show that random exploration of parasitism, free-riding and altruism
enables coexistence of the three strategies without the need of reciprocating,
punishing or rewarding strategies. To finish, the problem of the limitation of
resources is reviewed, showing that...


title: Theory of Charge and Heat Polarizations with the Keldysh Formalism

abstract:
  We investigate the heat polarization, a heat analog of the charge
polarization, by using the gauge-covariant Keldysh formalism. In contrast to
the charge-heat analogy naively expected, we find that the heat polarization
does not appear spontaneously, since it consists not only of the heat-transfer
contribution but of the heat-generation contribution, leading to the Mott rule.
Nonetheless, it can be induced by a torsional magnetic field in $(3+1)$-D
topological insulators and superconductors, which is described by the temporal
part of the Nieh-Yan action.


title: Lipschitz regularity of the eigenfunctions on optimal domains

abstract:
  We study the optimal sets $\Omega^\ast\subset\mathbb{R}^d$ for spectral
functionals $F\big(\lambda_1(\Omega),\dots,\lambda_p(\Omega)\big)$, which are
bi-Lipschitz with respect to each of the eigenvalues
$\lambda_1(\Omega),\dots,\lambda_p(\Omega)$ of the Dirichlet Laplacian on
$\Omega$, a prototype being the problem $$ \min{\big\{\lambda_1(\Omega)+\dots+
\lambda_p(\Omega)\;:\;\Omega\subset\mathbb{R}^d,\ |\Omega|=1\big\}}. $$ We
prove the Lipschitz regularity of the eigenfunctions $u_1,\dots,u_p$ of the
Dirichlet Laplacian on the optimal set $\Omega^*$ and, as a corollary, we
deduce that $\Omega^*$ is open. For functionals depending only on a generic
subset of the spectrum, as for example $\lambda_k(\Omega)$ or
$\lambda_{k_1}(\Omega)+\dots+\lambda_{k_p}(\Omega)$, our result proves only the
existence of a Lipschitz continuous eigenfunction in correspondence to each of
the eigenvalues involved.


title: Scarcity may promote cooperation in populations of simple agents

abstract:
  In the study of the evolution of cooperation, resource limitations are
usually assumed just to provide a finite population size. Recently, however, it
has been pointed out that resource limitation may also generate dynamical
payoffs able to modify the original structure of the games. Here we study
analytically a phase transition from a homogeneous population of defectors when
resources are abundant to the survival of unconditional cooperators when
resources reduce below a threshold. To this end, we introduce a model of simple
agents, with no memory or ability of recognition, interacting in well-mixed
populations. The result might shed light on the role played by resource
constraints on the origin of multicellularity.


title: Baryon spectrum in a finite-temperature AdS/QCD model

abstract:
  We propose a model for baryons at finite temperature using AdS/QCD
correspondence. In this model, we modify the AdS spacetime into the
AdS-Schwarzchild spacetime and consider a couple of bulk spinors in this
background. Solving this model, we get an eigenvalue equation for the baryon
masses. We then investigate the effects of temperature on the baryon masses
numerically, and find an interesting temperature dependence. Our result is
consistent with the results from lattice QCD and other phenomenological models.


title: Meromorphic infinitesimal affine actions of the plane

abstract:
  We study complex Lie algebras spanned by pairs \left(Z,Y\right) of germs of a
meromorphic vector field of the complex plane satisfying
\left[Z,Y\right]=\delta Y for some \delta\in\ww C . This topic relates to
Liouville-integrability of the differential equation induced by the foliation
underlying Z . We give a direct geometric proof of a result by M. Berthier and
F. Touzet characterizing germs of a foliation admitting a first-integral in a
Liouvillian extension of the standard differential field. In so doing we study
transverse and tangential rigidity properties when Z is holomorphic and its
linear part is not nilpotent. A second part of the article is devoted to
computing the Galois-Malgrange groupoid of meromorphic Z .


title:
Measurement of the Aharonov-Casher geometric phase with a separated-arm
  atom interferometer

abstract:
  In this letter, we report a measurement of the Aharonov-Casher (AC) geometric
phase with our lithium atom interferometer. The AC phase appears when a
particle carrying a magnetic dipole propagates in a transverse electric field.
The first measurement of the AC phase was done with a neutron interferometer in
1989 by A. Cimmino \textit{et al.} (Phys. Rev. Lett. \textbf{63}, 380, 1989)
and all the following experiments were done with Ramsey or Ramsey-Bord\'e
interferometers with molecules or atoms. In our experiment, we use lithium
atoms pumped in a single hyperfine-Zeeman sublevel and we measure the AC-phase
by applying opposite electric fields on the two interferometer arms. Our
measurements are in good agreement with the expected theoretical values and
they prove that this phase is independent of the atom velocity.


title: Phonons and Thermodynamics of LiMPO4 (M=Mn, Fe)

abstract:
  Lithium transition metal phospho-olivines are useful electrode materials,
owing to their stability, high safety, low cost and cyclability. We report
phonon studies using neutron inelastic scattering experiments, ab-initio
density functional theory calculations and potential model calculations on
LiMPO4 (M=Mn, Fe) at ambient and high temperature to understand the microscopic
picture of Li sub-lattice. The experiments are in good agreement with
calculations. The lattice dynamics calculations indicate instability of a
zone-centre as well as zone-boundary modes along (100) at volume corresponding
to high temperature. The unstable phonon modes show mainly large vibration of
Li atoms in the x-z plane of the orthorhombic structure (space group Pbnm).
Molecular dynamics simulations with increasing temperature indicate large mean
square displacement of Li as compared to other constituent atoms. The computed
pair-correlations between various atom pairs show that there is local disorder
occurring in the lithium sub-lattice with increasing temperature, while other
pairs show minimal changes. The results find the two compounds to be thermally
stable up to high temperatures, which is a desirable trait for its battery
applications.


title: Low Latency Datacenter Networking: A Short Survey

abstract:
  Datacenters are the cornerstone of the big data infrastructure supporting
numerous online services. The demand for interactivity, which significantly
impacts user experience and provider revenue, is translated into stringent
timing requirements for flows in datacenter networks. Thus low latency
networking is becoming a major concern of both industry and academia.
  We provide a short survey of recent progress made by the networking community
for low latency datacenter networks. We propose a taxonomy to categorize
existing work based on four main techniques, reducing queue length,
accelerating retransmissions, prioritizing mice flows, and exploiting
multi-path. Then we review select papers, highlight the principal ideas, and
discuss their pros and cons. We also present our perspectives of the research
challenges and opportunities, hoping to aspire more future work in this space.


title: Foldy-Wouthuysen Transformation, Scalar Potentials and Gravity

abstract:
  We show that care is required in formulating the nonrelativistic limit of
generalized Dirac Hamiltonians which describe particles and antiparticles
interacting with static electric and/or gravitational fields. The Dirac-Coulomb
and the Dirac-Schwarzschild Hamiltonians, and the corrections to the Dirac
equation in a non-inertial frame, according to general relativity, are used as
example cases in order to investigate the unitarity of the standard and
"chiral" approaches to the Foldy-Wouthuysen transformation, and spurious
parity-breaking terms. Indeed, we find that parity-violating terms can be
generated by unitary pseudo-scalar transformations ("chiral" Foldy-Wouthuysen
transformations). Despite their interesting algebraic properties, we find that
"chiral" Foldy-Wouthuysen transformations change fundamental symmetry
properties of the Hamiltonian and do not conserve the physical interpretation
of the operators. Supplementing the discussion, we calculate the leading terms
in the Foldy-Wouthuysen transformation of the Dirac Hamiltonian with a scalar
potential (of the (1/r)-form and of the confining radially symmetric linear
form), and obtain compact expressions for the leading higher-order corrections
to the Dirac Hamiltonian in a non-inertial rotating reference frame "Mashhoon
term").


title:
Existence of nodal solutions for quasilinear elliptic problems in
  $\mathbb{R}^N$

abstract:
  We prove the existence of one positive, one negative, and one sign-changing
solution of a $p$-Laplacian equation on $\mathbb{R}^N$, with a $p$-superlinear
subcritical term. Sign-changing solutions of quasilinear elliptic equations set
on the whole of $\mathbb{R}^N$ have only been scarcely investigated in the
literature. Our assumptions here are similar to those previously used by some
authors in bounded domains, and our proof uses fairly elementary critical point
theory, based on constraint minimization on the nodal Nehari set. The lack of
compactness due to the unbounded domain is overcome by working in a suitable
weighted Sobolev space.


title:
Multiwavelength Probes of the Environs of Relativistic Shocks in Blazar
  Jets

abstract:
  Diffusive shock acceleration (DSA) at relativistic shocks is likely to be an
important acceleration mechanism in various astrophysical jet sources,
including radio-loud AGN. An important recent development for blazar science is
the ability of Fermi-LAT data to pin down the power-law index of the high
energy portion of emission in these sources, and therefore also the index of
the underlying non-thermal particle population. This diagnostic potential was
not possible prior to Fermi launch, when gamma-ray information was dominated by
the highly-absorbed TeV band. This paper highlights how multiwavelength spectra
including X-ray band and Fermi data can be used to probe diffusive acceleration
in relativistic, oblique, MHD shocks in blazar jets. The spectral index of the
non-thermal particle distributions resulting from Monte Carlo simulations of
DSA, and the fraction of thermal particles accelerated to non-thermal energies,
depend sensitively on the particles' mean free path scale, and also on the
magnetic field obliquity to the shock normal. We investigate self-consistently
the radiative synchrotron/Compton signatures of the resulting thermal and
non-thermal particle distributions. Important constraints on the frequency of
particle scattering and the level of field turbulence are identified for the
blazar AO 0235+164. The possible interpretation that turbulence levels decline
with remoteness from jet shocks, and a significant role for non-gyroresonant
diffusion, are discussed.