title:
Probing electron transport across a LSMO/Nb:STO heterointerface at the
  nanoscale

abstract:
  We investigate electron transport across a complex oxide heterointerface of
La$_{0.67}$Sr$_{0.33}$MnO$_3$ (LSMO) on Nb:SrTiO$_3$ (Nb:STO) at different
temperatures. For this, we employ the conventional current-voltage method as
well as the technique of Ballistic Electron Emission Microscopy (BEEM), which
can probe lateral inhomogeneities in transport at the nanometer scale. From
current-voltage measurements, we find that the Schottky Barrier height (SBH) at
the LSMO/Nb:STO interface decreases at low temperatures accompanied by a larger
than unity ideality factor. This is ascribed to the tunneling dominated
transport caused by the narrowing of the depletion width at the interface.
However, BEEM studies of such unbiased interfaces, do not exhibit SBH lowering
at low temperatures, implying that this is triggered by the modification of the
interface due to an applied bias and is not an intrinsic property of the
interface. Interestingly, the SBH at the nanoscale, as extracted from BEEM
studies, at different locations in the device is found to be spatially
homogeneous and similar both at room temperature and at low temperatures. Our
results highlight the application of BEEM in characterizing electron transport
and their homogeneity at such unbiased complex oxide interfaces and yields new
insights into the origin of the temperature dependence of the SBH at biased
interfaces.


title:
Low temperature investigations and surface treatments of colloidal
  narrowband fluorescent nanodiamonds

abstract:
  We report fluorescence investigations and Raman spectroscopy on colloidal
nanodiamonds (NDs) obtained via bead assisted sonic disintegration (BASD) of a
polycrystalline chemical vapor deposition film. The BASD NDs contain in situ
created silicon vacancy (SiV) centers. Whereas many NDs exhibit emission from
SiV ensembles, we also identify NDs featuring predominant emission from a
single bright SiV center. We demonstrate oxidation of the NDs in air as a tool
to optimize the crystalline quality of the NDs via removing damaged regions
resulting in a reduced ensemble linewidth as well as single photon emission
with increased purity. We furthermore investigate the temperature dependent
zero-phonon-line fine-structure of a bright single SiV center as well as the
polarization properties of its emission and absorption.


title: Lefschetz for local Picard groups

abstract:
  We prove a strengthening of the Grothendieck-Lefschetz hyperplane theorem for
local Picard groups conjectured by Koll\'ar. Our approach, which relies on
acyclicity results for absolute integral closures, also leads to a restriction
theorem for higher rank bundles on projective varieties in positive
characteristic.


title: Signatures, Heegaard Floer correction terms and quasi-alternating links

abstract:
  Turaev showed that there is a well-defined map assigning to an oriented link
L in the three-sphere a Spin structure t_0 on Sigma(L), the 2-fold cover of S^3
branched along L. We prove, generalizing results of Manolescu-Owens and
Donald-Owens, that for an oriented quasi-alternating link L the signature of L
equals minus four times the Heegaard Floer correction term of (Sigma(L), t_0).


title:
Whitney-Holder continuity of the SRB measure for transversal families of
  smooth unimodal maps

abstract:
  We consider C^2 families t->f_t of C^4 nondegenerate unimodal maps. We study
the absolutely continuous invariant probability (SRB) measure m_t of f_t, as a
function of t on the set of Collet-Eckmann (CE) parameters:
  Upper bounds: Assuming existence of a transversal CE parameter, we find a
positive measure set D of CE parameters, and, for each s in D, a subset D0 of D
of polynomially recurrent parameters containing s as a Lebesgue density point,
and constants C>1, G >4, so that, for every 1/2-Holder function A (of
1/2-Holder norm |A|) and all t in D0,
  |\int A dm_t -\int A dm_s| < C |A| |t-s|^{1/2} |log|t-s||^G
  (If f_t(x)=tx(1-x), the set D contains almost all CE parameters.)
  Lower bounds: Assuming existence of a transversal mixing Misiurewicz-Thurston
parameter s, we find a set of CE parameters D' accumulating at s, a constant C
>1, and an infinitely differentiable function B, so that for all t in D'
  C |t-s|^{1/2} > |\int B dm_t -\int B dm_s| > |t-s|^{1/2}/C


title: Some properties of finite rings

abstract:
  A well-known theorem of Wedderburn asserts that a finite division ring is
commutative. In a division ring the group of invertible elements is as large as
possible. Here we will be particularly interested in the case where this group
is as small as possible, namely reduced to 1. We will show that, if this is the
case, then the ring is boolean. Thus, here too, the ring is commutative.


title: On separately subharmonic and harmonic functions

abstract:
  We improve our previous generalizations to Arsove's and Ko\lodziej's and
Thorbi\"ornson's results concerning the subharmonicity of a function
subharmonic with respect to the first variable and harmonic with respect to the
second.


title: Contribution to the ergodic theory of robustly transitive maps

abstract:
  In this article we intend to contribute in the understanding of the ergodic
properties of the set RT of robustly transitive local diffeomorphisms on a
compact manifold M without boundary. We prove that there exists a C^1 residual
subset R_0 of RT such that any f in R_0 has a residual subset of M with dense
pre-orbits. Moreover, C^1 generically in the space of local diffeomorphisms
with no splitting and all points with dense pre-orbit, there are uncountably
many ergodic expanding invariant measures with full support and exhibiting
exponential decay of correlations. In particular, these results hold for an
important class of robustly transitive maps considered in [Lizana-Pujals'12].


title: Starling flock networks manage uncertainty in consensus at low cost

abstract:
  Flocks of starlings exhibit a remarkable ability to maintain cohesion as a
group in highly uncertain environments and with limited, noisy information.
Recent work demonstrated that individual starlings within large flocks respond
to a fixed number of nearest neighbors, but until now it was not understood why
this number is seven. We analyze robustness to uncertainty of consensus in
empirical data from multiple starling flocks and show that the flock
interaction networks with six or seven neighbors optimize the trade-off between
group cohesion and individual effort. We can distinguish these numbers of
neighbors from fewer or greater numbers using our systems-theoretic approach to
measuring robustness of interaction networks as a function of the network
structure, i.e., who is sensing whom. The metric quantifies the disagreement
within the network due to disturbances and noise during consensus behavior and
can be evaluated over a parameterized family of hypothesized sensing strategies
(here the parameter is number of neighbors). We use this approach to further
show that for the range of flocks studied the optimal number of neighbors does
not depend on the number of birds within a flock; rather, it depends on the
shape, notably the thickness, of the flock. The results suggest that robustness
to uncertainty may have been a factor in the evolution of flocking for
starlings. More generally, our results elucidate the role of the interaction
network on uncertainty management in collective behavior, and motivate the
application of our approach to other biological networks.

categories: q-bio.PE nlin.AO physics.bio-ph q-bio.QM


title: Biophysics of filament length regulation by molecular motors

abstract:
  Regulating physical size is an essential problem that biological organisms
must solve from the subcellular to the organismal scales, but it is not well
understood what physical principles and mechanisms organisms use to sense and
regulate their size. Any biophysical size-regulation scheme operates in a noisy
environment and must be robust to other cellular dynamics and fluctuations.
This work develops theory of filament length regulation inspired by recent
experiments on kinesin-8 motor proteins, which move with directional bias on
microtubule filaments and alter microtubule dynamics. Purified kinesin-8 motors
can depolymerize chemically-stabilized microtubules. In the length-dependent
depolymerization model, the rate of depolymerization tends to increase with
filament length, because long filaments accumulate more motors at their tips
and therefore shorten more quickly. When balanced with a constant filament
growth rate, this mechanism can lead to a fixed polymer length. However, the
mechanism by which kinesin-8 motors affect the length of dynamic microtubules
in cells is less clear. We study the more biologically realistic problem of
microtubule dynamic instability modulated by a motor-dependent increase in the
filament catastrophe frequency. This leads to a significant decrease in the
mean filament length and a narrowing of the filament length distribution. The
results improve our understanding of the biophysics of length regulation in
cells.


title: Bridging stylized facts in finance and data non-stationarities

abstract:
  Employing a recent technique which allows the representation of nonstationary
data by means of a juxtaposition of locally stationary patches of different
length, we introduce a comprehensive analysis of the key observables in a
financial market: the trading volume and the price fluctuations. From the
segmentation procedure we are able to introduce a quantitative description of a
group of statistical features (stylizes facts) of the trading volume and price
fluctuations, namely the tails of each distribution, the U-shaped profile of
the volume in a trading session and the evolution of the trading volume
autocorrelation function. The segmentation of the trading volume series
provides evidence of slow evolution of the fluctuating parameters of each
patch, pointing to the mixing scenario. Assuming that long-term features are
the outcome of a statistical mixture of simple local forms, we test and compare
different probability density functions to provide the long-term distribution
of the trading volume, concluding that the log-normal gives the best agreement
with the empirical distribution. Moreover, the segmentation of the magnitude
price fluctuations are quite different from the results for the trading volume,
indicating that changes in the statistics of price fluctuations occur at a
faster scale than in the case of trading volume.


title: Direct CP Violation in Nonleptonic Charm Decays

abstract:
  LHCb, CDF and most recently Belle have observed a large difference between
direct CP asymmetries in $D^0\to K^+K^-$ and $D^0\to\pi^+\pi^-$. We use the
measured value of $\Delta A_{CP}$ to constrain the magnitude and strong phase
of a QCD-enhanced standard model penguin and predict its effects on direct CP
asymmetry in $D^0\to\pi^0\pi^0$ and $D^+\to K^+\bar{K}^0$.


title: Core-halo instability in dynamical systems

abstract:
  This paper proves an instability theorem for dynamical systems. As one adds
interactions between subystems in a complex system, structured or random, a
threshold of connectivity is reached beyond which the overall dynamics
inevitably goes unstable. The threshold occurs at the point at which flows and
interactions between subsystems (`surface' effects) overwhelm internal
stabilizing dynamics (`volume' effects). The theorem is used to identify
instability thresholds in systems that possess a core-halo or core-periphery
structure, including the gravo-thermal catastrophe -- i.e., star collapse and
explosion -- and the interbank payment network. In the core-halo model, the
same dynamical instability underlies both gravitational and financial collapse.


title: Peeling the Grid

abstract:
  Consider the set of points formed by the integer $n \times n$ grid, and the
process that in each iteration removes from the point set the vertices of its
convex-hull. Here, we prove that the number of iterations of this process is
O(n^{4/3}); that is, the number of convex layers of the $n\times n$ grid is
\Theta(n^{4/3}).


title:
$Lmc-$compactification of a semitopological semigroup as a space of
  e-ultrafilters

abstract:
  Let $S$ be a semitopological semigroup and $\mathcal{CB}(S)$ denotes the
$C^*$-algebra of all bounded complex valued continuous functions on $S$ with
uniform norm. A function $f\in \mathcal{CB}(S)$ is left multiplicative
\linebreak continuous if and only if $\mathbf{T}_{\mu}f\in \mathcal{CB}(S)$ for
all $\mu$ in the spectrum of $\mathcal{CB}(S)$, where
$\mathbf{T}_{\mu}f(s)=\mu(L_sf)$ and $L_sf(x)=f(sx)$ for each $s,x\in S$. The
collection of all left multiplicative continuous functions on $S$ is denoted by
$Lmc(S)$. In this paper, the $Lmc-$compactification of a semitopological
semigroup S is reconstructed as a space of $e-$ultrafilters. This construction
is applied to obtain some algebraic properties of \linebreak $(\varepsilon
,\s)$, that $ \s $ is the spectrum of $Lmc(S)$, for semitopological semigroups
$S$. It is shown that if S is a locally compact semitopological semigroup, then
$S^*=\s \setminus \varepsilon(S)$ is a left ideal of $\s$ if and only if for
each $x,y\in S$, there exists a compact zero set $A$ such that $x\in A$ and
$\{t\in S:yt\in A\}$ is a compact set.


title: Simplification of the majorizing measures method, with development

abstract:
  We update, specify, review and develop in this article the classical
majorizing measures method for investigation of the local structure of random
fields, belonging to X.Fernique and M.Talagrand in order to simplify and
improve the constant values.
  Our considerations based on the generalization of the L.Arnold and P.Imkeller
generalization of classical Garsia-Rodemich-Rumsey inequality.


title:
Local Privacy, Data Processing Inequalities, and Statistical Minimax
  Rates

abstract:
  Working under a model of privacy in which data remains private even from the
statistician, we study the tradeoff between privacy guarantees and the utility
of the resulting statistical estimators. We prove bounds on
information-theoretic quantities, including mutual information and
Kullback-Leibler divergence, that depend on the privacy guarantees. When
combined with standard minimax techniques, including the Le Cam, Fano, and
Assouad methods, these inequalities allow for a precise characterization of
statistical rates under local privacy constraints. We provide a treatment of
several canonical families of problems: mean estimation, parameter estimation
in fixed-design regression, multinomial probability estimation, and
nonparametric density estimation. For all of these families, we provide lower
and upper bounds that match up to constant factors, and exhibit new (optimal)
privacy-preserving mechanisms and computationally efficient estimators that
achieve the bounds.


title:
Filters and the weakly almost periodic compactification of a
  semitopological semigroup

abstract:
  Let $S$ be a semitopological semigroup. The $wap-$ compactification of
semigroup S, is a compact semitopological semigroup with certain universal
properties relative to the original semigroup, and the $Lmc-$ compactification
of semigroup $S$ is a universal semigroup compactification of $S$, which are
denoted by $S^{wap}$ and $S^{Lmc}$ respectively. In this paper, an internal
construction of the $wap-$compactification of a semitopological semigroup is
constructed as a space of $z-$filters. Also we obtain the cardinality of
$S^{wap}$ and show that if $S^{wap}$ is the one point compactification then
$(S^{Lmc}-S)*S^{Lmc}$ is dense in $S^{Lmc}-S$.


title:
Nonstandard Topology without Logic, Ultrafilters as infinitesimal points
  in topological space

abstract:
  Nonstandard analysis is very complex, so finding a simple description of
infinitesimal points will be useful. In this paper, ultrafilters as
infinitesimal points in a topological space will be proposed, and some
topological concepts is restated by this tools.


title: Dualities in population genetics: a fresh look with new dualities

abstract:
  We apply our general method of duality, introduced in [Giardina', Kurchan,
Redig, J. Math. Phys. 48, 033301 (2007)], to models of population dynamics. The
classical dualities between forward and ancestral processes can be viewed as a
change of representation in the classical creation and annihilation operators,
both for diffusions dual to coalescents of Kingman's type, as well as for
models with finite population size. Next, using SU(1,1) raising and lowering
operators, we find new dualities between the Wright-Fisher diffusion with $d$
types and the Moran model, both in presence and absence of mutations. These new
dualities relates two forward evolutions. From our general scheme we also
identify self-duality of the Moran model.

categories: math.PR math-ph math.MP physics.bio-ph q-bio.PE


title: A note on partial isometries on pseudo-Hilbert spaces

abstract:
  The aim of this paper is to show that two accessible subspaces in the Loynes
$\mathcal{Z}$ - space $\Hc$ are the initial and final space of a partial
gramian isometry, respectively if the norm of the difference of the associated
gramian selfadjoint projections is strictly less than 1.


title:
Effect of two-beam coupling in strong-field optical pump-probe
  experiments

abstract:
  Nonlinear optics experiments measuring phase shifts induced in a weak probe
pulse by a strong pump pulse must account for coherent effects that only occur
when the pump and probe pulses are temporally overlapped. It is well known that
a weak probe beam experiences a greater phase shift from a strong pump beam
than the pump beam induces on itself. The physical mechanism behind the
enhanced phase shift is diffraction of pump light into the probe direction by a
nonlinear refractive index grating produced by interference between the two
beams. For an instantaneous third-order response, the effect of the grating is
to simply double the probe phase shift, but when delayed nonlinearities are
considered, the effect is more complex. A comprehensive treatment is given for
both degenerate and nondegenerate pump-probe experiments in noble and diatomic
gases. Results of numerical calculations are compared to a recent transient
birefringence measurement [Loriot et al., Opt. Express 17, 13429 (2009)] and a
recent spectral interferometry experiment [Wahlstrand et al., Phys. Rev. A 85,
043820 (2012)]. We also present results from two new experiments using
spectrally-resolved transient birefringence with 800 nm pulses in Ar and air
and degenerate chirped pulse spectral interferometry in Ar. Both experiments
support the interpretation of the negative birefringence at high intensity as
arising from a plasma grating.


title: "Groupware for Groups": Problem-Driven Design in Deme

abstract:
  Design choices can be clarified when group interaction software is directed
at solving the interaction needs of particular groups that pre-date the
groupware. We describe an example: the Deme platform for online deliberation.
Traditional threaded conversation systems are insufficient for solving the
problem at which Deme is aimed, namely, that the democratic process in
grassroots community groups is undermined both by the limited availability of
group members for face-to-face meetings and by constraints on the use of
information in real-time interactions. We describe and motivate design
elements, either implemented or planned for Deme, that addresses this problem.
We believe that "problem focused" design of software for preexisting groups
provides a useful framework for evaluating the appropriateness of design
elements in groupware generally.


title:
Characterization of protonated and deuterated Tetra-Phenyl Butadiene
  Film in a Polystyrene Matrix

abstract:
  We study the effect of deuteration and annealing on the fluorescence spectrum
shape and VUV to visible conversion efficiency of TPB films in a polystyrene
matrix with input light from 120 to 220 nm. We observed no discernible
difference in the fluorescence spectrum shape between any of the films. The
deuterated film performed equally well compared to the standard one in terms of
conversion efficiency, but annealing seems to degrade this efficiency to
roughly 75% of its non annealed value at all wavelengths studied.


title: On isomorphisms of Banach spaces of continuous functions

abstract:
  We prove that if $K$ and $L$ are compact spaces and $C(K)$ and $C(L)$ are
isomorphic as Banach spaces then $K$ has a $\pi$-base consisting of open sets
$U$ such that $\bar{U}$ is a continuous image of some compact subspace of $L$.
This gives some information on isomorphic classes of the spaces of the form
$C([0,1]^\kappa)$ and $C(K)$ where $K$ is Corson compact.


title: Hitting Times, Cover Cost, and the Wiener Index of a Tree

abstract:
  We exhibit a close connection between hitting times of the simple random walk
on a graph, the Wiener index, and related graph invariants. In the case of
trees we obtain a simple identity relating hitting times to the Wiener index.
  It is well known that the vertices of any graph can be put in a linear
preorder so that vertices appearing earlier in the preorder are "easier to
reach" by a random walk, but "more difficult to get out of". We define various
other natural preorders and study their relationships. These preorders coincide
when the graph is a tree, but not necessarily otherwise.
  Our treatise is self-contained, and puts some known results relating the
behaviour or random walk on a graph to its eigenvalues in a new perspective.


title:
Analysis of the Instability Growth Rate During the Jet - Background
  Interaction in the Magnetic Field

abstract:
  The two-stream instability is a common instability, responsible for many
observed phenomena in nature, especially the interaction of jets of various
origin with the background plasma (e.g. extragalactic jet interacting with the
cosmic background). The dispersion relation not considering magnetic field is
described by the well-known Buneman relation. In 2011, Bohata, Bren, and
Kulhanek derived the relation for the two-stream instability without the cold
limit, with the general orientation of magnetic field, and arbitrary stream
directions. The maximum value of the imaginary part of the individual
dispersion branches is of interest from the physical point of view. It
represents the instability growth rate which is responsible for the turbulence
mode onset and subsequent reconnection on the ion radius scale accompanied by a
strong plasma thermalization. The paper presented here is focused on the
non-relativistic instability growth rate and its dependence on various input
parameters, such as magnitude and direction of magnetic field, sound velocity,
plasma frequency of the jet and direction of the wave vector during the jet -
background interaction. The results are presented in well-arranged plots and
can be used for determination of the plasma parameter values close to which the
strong energy transfer and thermalization between the jet and the background
plasma occur.


title:
A Monte Carlo Code for Relativistic Radiation Transport Around Kerr
  Black Holes

abstract:
  We present a new code for radiation transport around Kerr black holes,
including arbitrary emission and absorption terms, as well as electron
scattering and polarization. The code is particularly useful for analyzing
accretion flows made up of optically thick disks and optically thin coronae. We
give a detailed description of the methods employed in the code, and also
present results from a number of numerical tests to assess its accuracy and
convergence.


title:
Descente galoisienne sur le second groupe de Chow : mise au point et
  applications

abstract:
  Connections between the second Chow group of a smooth projective variety and
its third unramified cohomology group, with coefficients the roots of unity
twisted twice, feature in several recent works. In this note we revisit a 1996
paper by B. Kahn and specialize it to various types of rationally connected
varieties.


title:
Thermodynamic consistency in variable-level coarse-graining of polymeric
  liquids

abstract:
  Numerically optimized reduced descriptions of macromolecular liquids often
present thermodynamic inconsistency with atomistic level descriptions even if
the total correlation function, i.e. the structure, appears to be in agreement.
An analytical expression for the effective potential between a pair of
coarse-grained units is derived starting from the first-principles
Ornstein-Zernike equation, for a polymer liquid where each chain is represented
as a collection of interpenetrating blobs, with a variable number of blobs,
$n_b$, of size $N_b$. The potential is characterized by a long tail, slowly
decaying with characteristic scaling exponent of $N_b^{1/4}$. This general
result applies to any coarse-grained model of polymer melts with units larger
than the persistence length, highlighting the importance of the long,
repulsive, potential tail for the model to correctly predict both structural
and thermodynamic properties of the macromolecular liquid.


title:
On the link between Octahedral Rotations and Conductivity in the Domain
  Walls of BiFeO3

abstract:
  We analyze the hypothetical link between octahedral straightening and
increased conductivity inside the domain walls of BiFeO3. Our calculations for
109 degree walls predict a lattice parameter expansion of c.a. 1 percent in the
direction perpendicular to the wall, and an associated straightening of the
octahedral rotation angle of 4 degrees, which is comparable to that observed in
the high temperature metallic phase of BiFeO3. On the other hand, in the
closely related family of rare-earth orthoferrites, straighter octahedra do not
correlate with increased bandgap, which suggests that the correlation between
octahedral straightening and bandgap reduction in BiFeO3 is perhaps fortuitous
and not necessarily the cause of increased conductivity at the walls.


title: Indication on the process-dependence of the Sivers effect

abstract:
  We analyze the spin asymmetry for single inclusive jet production in
proton-proton collisions collected by AnDY experiment at the Relativistic Heavy
Ion Collider and the Sivers asymmetry data from semi-inclusive deep inelastic
scattering experiments. In particular, we consider the role color gauge
invariance plays in determining the process-dependence of the Sivers effect. We
find that after carefully taking into account the initial-state and final-state
interactions between the active parton and the remnant of the polarized hadron,
the calculated jet spin asymmetry based on the Sivers functions extracted from
HERMES and COMPASS experiments is consistent with the AnDY experimental data.
This provides a first indication for the process-dependence of the Sivers
effect in these processes. We also make predictions for both direct photon and
Drell-Yan spin asymmetry, to further test the process-dependence of the Sivers
effect in future experiments.


title: An Efficient Dual Approach to Distance Metric Learning

abstract:
  Distance metric learning is of fundamental interest in machine learning
because the distance metric employed can significantly affect the performance
of many learning methods. Quadratic Mahalanobis metric learning is a popular
approach to the problem, but typically requires solving a semidefinite
programming (SDP) problem, which is computationally expensive. Standard
interior-point SDP solvers typically have a complexity of $O(D^{6.5})$ (with
$D$ the dimension of input data), and can thus only practically solve problems
exhibiting less than a few thousand variables. Since the number of variables is
$D (D+1) / 2 $, this implies a limit upon the size of problem that can
practically be solved of around a few hundred dimensions. The complexity of the
popular quadratic Mahalanobis metric learning approach thus limits the size of
problem to which metric learning can be applied. Here we propose a
significantly more efficient approach to the metric learning problem based on
the Lagrange dual formulation of the problem. The proposed formulation is much
simpler to implement, and therefore allows much larger Mahalanobis metric
learning problems to be solved. The time complexity of the proposed method is
$O (D ^ 3) $, which is significantly lower than that of the SDP approach.
Experiments on a variety of datasets demonstrate that the proposed method
achieves an accuracy comparable to the state-of-the-art, but is applicable to
significantly larger problems. We also show that the proposed method can be
applied to solve more general Frobenius-norm regularized SDP problems
approximately.


title: G2 can Illuminate the Black Hole Population near the Galactic Center

abstract:
  Galactic nuclei are expected to be densely populated with stellar and
intermediate mass black holes. Exploring this population will have important
consequences for the observation prospects of gravitational waves as well as
understanding galactic evolution. The gas cloud G2 currently approaching Sgr A*
provides an unprecedented opportunity to probe the black hole and neutron star
population of the Galactic nucleus. We examine the possibility of a G2-black
hole encounter and its detectability with current X-ray satellites, such as
Chandra and NuSTAR. We find that multiple encounters are likely to occur close
to the pericenter, which may be detectable upon favorable circumstances. This
opportunity provides an additional, important science case for leading X-ray
observatories to closely follow G2 on its way to the nucleus.


title: Demographics of the Galaxies Hosting Short-duration Gamma-Ray Bursts

abstract:
  We present observations of the afterglows and host galaxies of three
short-duration gamma-ray bursts (GRBs): 100625A, 101219A and 110112A. We find
that GRB 100625A occurred in a z=0.452 early-type galaxy with a stellar mass of
4.6e9 M_Sun and a stellar population age of 0.7 Gyr, and GRB 101219A originated
in a star-forming galaxy at z=0.718 with a stellar mass of 1.4e9 M_Sun, a star
formation rate of 16 M_Sun yr^-1, and a stellar population age of 50 Myr. We
also report the discovery of the optical afterglow of GRB 110112A, which lacks
a coincident host galaxy to i>26 mag and we cannot conclusively identify any
field galaxy as a possible host. The bursts have inferred circumburst densities
of ~1e-4-1 cm^-3, and isotropic-equivalent gamma-ray and kinetic energies of
1e50-1e51 erg. These events highlight the diversity of galaxies that host short
GRBs. To quantify this diversity, we use the sample of 36 Swift short GRBs with
robust associations to an environment (~1/2 of 68 short bursts detected by
Swift to May 2012) and classify them as follows: late-type (50%), early-type
(15%), inconclusive (20%), and host-less (lacking a coincident host galaxy to
limits of >26 mag; 15%). To find likely ranges for the true late- and
early-type fractions, we assign each of the host-less bursts to the late- or
early-type category using probabilistic arguments, and consider the scenario
that all hosts in the inconclusive category are early-type galaxies to set an
upper bound on the early-type fraction. The most likely ranges for the late-
and early-type fractions are ~60-80% and ~20-40%, respectively. We find no
clear trend between gamma-ray duration and host type, and no change to the
fractions when excluding events recently claimed as possible contaminants from
the long GRB/collapsar population. Our reported demographics are consistent
with a short GRB rate driven by both stellar mass and star formation.


title: Gravitational Scattering Of Photons Off Cosmic Strings

abstract:
  Photons can gravitationally scatter off a cosmic string loop and gain or lose
energy. We consider the spectral distortion induced by cosmic string loops
placed in an ambient thermal bath of photons. The fractional deviation from a
thermal spectrum caused by cosmic strings is estimated to scale as (G_N \mu)^2
z^2, where G_N is Newton's constant, $\mu$ is the string tension, and z is the
cosmological redshift after which spectral distortions can survive. This effect
is large enough to potentially be of observational interest.


title: Gauged supergravities and their symmetry-breaking vacua in F-theory

abstract:
  We first derive a class of six-dimensional (1,0) gauged supergravities
arising from threefold compactifications of F-theory with background fluxes.
The derivation proceeds via the M-theory dual reduction on an SU(3)-structure
manifold with four-form G_4-flux. We then show that vacuum solutions of these
six-dimensional theories describes four-dimensional flat space times a compact
two-dimensional internal space with additional localized sources. This induces
a spontaneous compactification to four space-time dimensions and breaks the
supersymmetry from N=2 to N=1, which allows the reduced theory to have a
four-dimensional chiral spectrum. We perform the reduction explicitly and
derive the N=1 characteristic data of the four-dimensional effective theory.
The match with fourfold reductions of F-theory is discussed and many of the
characteristic features are compared. We comment, in particular, on warping
effects and one-loop Chern-Simons terms generically present in four-dimensional
F-theory reductions.


title: Bringing the Visible Universe into Focus with Robo-AO

abstract:
  Light from astronomical objects must travel through the earth's turbulent
atmosphere before it can be imaged by ground-based telescopes. To enable direct
imaging at maximum theoretical angular resolution, advanced techniques such as
those employed by the Robo-AO adaptive-optics system must be used.


title: A Gauge Field Theory of Continuous-Spin Particles

abstract:
  We propose and quantize a local, covariant gauge-field action that unifies
the description of all free helicity and continuous-spin degrees of freedom in
a simple manner. This is the first field-theory action of any kind for
continuous spin particles; it is consistent as a quantum theory and generalizes
to any number of dimensions. The fields live on the null cone of an internal
four-vector "spin-space"; in D dimensions a linearized gauge invariance reduces
their physical content to a single function on a Euclidean (D-2)-plane, on
which the little group E(D-2) acts naturally. A projective version of the
action further reduces the physical content to S^{D-3}, enabling a new local
description of particles with any spin structure, and in particular a tower of
all integer-helicity particles for D=4. Gauge-invariant interactions with a
background current are added in a straightforward manner.


title: CosMIn: The Solution to the Cosmological Constant Problem

abstract:
  The current acceleration of the universe can be modeled in terms of a
cosmological constant. We show that the extremely small value of \Lambda L_P^2
~ 3.4 x 10^{-122}, the holy grail of theoretical physics, can be understood in
terms of a new, dimensionless, conserved number CosMIn (N), which counts the
number of modes crossing the Hubble radius during the three phases of evolution
of the universe. Theoretical considerations suggest that N ~ 4\pi. This single
postulate leads us to the correct, observed numerical value of the cosmological
constant! This approach also provides a unified picture of cosmic evolution
relating the early inflationary phase to the late-time accelerating phase.


title:
A Topological Chern-Simons Sigma Model and New Invariants of
  Three-Manifolds

abstract:
  We construct a topological Chern-Simons sigma model on a Riemannian
three-manifold M with gauge group G whose hyperkahler target space X is
equipped with a G-action. Via a perturbative computation of its partition
function, we obtain new topological invariants of M that define new weight
systems which are characterized by both Lie algebra structure and hyperkahler
geometry. In canonically quantizing the sigma model, we find that the partition
function on certain M can be expressed in terms of Chern-Simons knot invariants
of M and the intersection number of certain G-equivariant cycles in the moduli
space of G-covariant maps from M to X. We also construct supersymmetric Wilson
loop operators, and via a perturbative computation of their expectation value,
we obtain new knot invariants of M that define new knot weight systems which
are also characterized by both Lie algebra structure and hyperkahler geometry.


title:
Quark Number Susceptibilities from Two-Loop Hard Thermal Loop
  Perturbation Theory

abstract:
  We use the recently obtained two-loop hard thermal loop perturbation theory
thermodynamics functions of a plasma of quarks and gluons to compute the
diagonal second- and fourth-order quark number susceptibilities. The two-loop
hard thermal loop perturbation theory thermodynamic functions used are reliable
in the limit that the ratio of the quark chemical potential to temperature is
small. Using this result, we are able to obtain (semi-)analytic expressions for
the quark number susceptibilities at leading- and next-to-leading-order in hard
thermal loop perturbation theory. We compare the hard thermal loop perturbation
theory results with perturbative quantum chromodynamics calculations, a
Polyakov-loop Nambu-Jona-Lasinio model calculation, and lattice quantum
chromodynamics results.


title: What if BR(h-->\mu\mu)/BR(h-->\tau\tau) does not equal m_\mu^2/m_\tau^2?

abstract:
  Measurements of the Yukawa couplings of the recently discovered boson h to
fermion pairs will provide a new arena for studying flavor physics. We analyze
the lessons that can be learned by measuring the h decay rates into the charged
lepton pairs, \tau\tau, \mu\mu, and \tau\mu. We demonstrate how this set of
measurements can distinguish in principle between various classes of flavor
models such as natural flavor conservation, minimal flavor violation, and
Froggatt-Nielsen symmetry.


title: Variable stars in the ultra-faint dwarf spheroidal galaxy Ursa Major I

abstract:
  We have performed the first study of the variable star population of Ursa
Major I (UMa I), an ultra-faint dwarf satellite recently discovered around the
Milky Way by the Sloan Digital Sky Survey. Combining time series observations
in the B and V bands from four different telescopes, we have identified seven
RR Lyrae stars in UMa I, of which five are fundamental-mode (RRab) and two are
first-overtone pulsators (RRc). Our V, B-V color-magnitude diagram of UMa I
reaches V~23 mag (at a signal-to-noise ratio of ~ 6) and shows features typical
of a single old stellar population. The mean pulsation period of the RRab stars
<Pab> = 0.628, {\sigma} = 0.071 days (or <Pab> = 0.599, {\sigma} = 0.032 days,
if V4, the longest period and brightest variable, is discarded) and the
position on the period-amplitude diagram suggest an Oosterhoff-intermediate
classification for the galaxy. The RR Lyrae stars trace the galaxy horizontal
branch at an average apparent magnitude of <V(RR)> = 20.43 +/- 0.02 mag
(average on 6 stars and discarding V4), giving in turn a distance modulus for
UMa I of (m-M)0 = 19.94 +/- 0.13 mag, distance d= 97.3 +6.0/-5.7 kpc, in the
scale where the distance modulus of the Large Magellanic Cloud is 18.5 +/- 0.1
mag. Isodensity contours of UMa I red giants and horizontal branch stars
(including the RR Lyrae stars identified in this study) show that the galaxy
has an S-shaped structure, which is likely caused by the tidal interaction with
the Milky Way. Photometric metallicities were derived for six of the UMa I RR
Lyrae stars from the parameters of the Fourier decomposition of the V-band
light curves, leading to an average metal abundance of [Fe/H] = -2.29 dex
({\sigma} = 0.06 dex, average on 6 stars) on the Carretta et al. metallicity
scale.


title:
Top Squark Searches Using Dilepton Invariant Mass Distributions and
  Bino-Higgsino Dark Matter at the LHC

abstract:
  Pair production of light top squarks at the 8-TeV LHC can be used to probe
the gaugino-Higgsino sector of the Minimal Supersymmetric Standard Model. The
case where the lightest neutralino is a mixture of Bino and Higgsino,
satisfying the thermal dark matter relic density, is investigated. In such a
scenario, the lightest top squark decays mostly into $(i)$ a top quark plus the
second or third lightest neutralino, and $(ii)$ a bottom quark plus the
lightest chargino, instead of a decay scenario of the lightest top squark into
a top quark and the lightest neutralino. Final states with $\geq 2$ jets,
dileptons, and missing energy are expected in a subsequent decay of the second
or third lightest neutralinos into the lightest neutralino via an intermediate
slepton ("light sleptons" case) or $Z$ boson ("heavy sleptons" case). The
opposite-sign same flavor dilepton mass distribution after subtracting the
opposite-sign different flavor distribution shows a clear edge in the case of
light sleptons. The significance for discovering such a scenario is calculated
with optimized cuts in both light and heavy sleptons cases.


title: Hedgehog ansatz and its generalization for self-gravitating Skyrmions

abstract:
  The hedgehog ansatz for spherically symmetric spacetimes in self-gravitating
nonlinear sigma models and Skyrme models is revisited and its generalization
for non-spherically symmetric spacetimes is proposed. The key idea behind our
construction is that, even if the matter fields depend on the Killing
coordinates in a nontrivial way, the corresponding energy-momentum tensor can
still be compatible with spacetime symmetries. Our generalized hedgehog ansatz
reduces the Skyrme equations to coupled differential equations for two scalar
fields together with several constraint equations between them. Some particular
field configurations satisfying those constraints are presented in several
physically important spacetimes, including stationary and axisymmetric
spacetimes. Incidentally, several new exact solutions are obtained under the
standard hedgehog ansatz, one of which represents a global monopole inside a
black hole with the Skyrme effect.


title: The evolution of the jet from Herbig Ae star HD 163296 from 1999 to 2011

abstract:
  Young A and B stars, the so-called Herbig Ae/Be stars (HAeBe), are surrounded
by an active accretion disk and drive outflows. We study the jet HH 409, which
is launched from the HAeBe star HD 163296, using new and archival observations
from Chandra and HST/STIS. In X-rays we can show that the central source is not
significantly extended. The approaching jet, but not the counter-jet, is
detected in Ly alpha. In addition, there is red-shifted Ly alpha emission
extended in the same direction as the jet, that is also absent in the
counter-jet. We can rule out an accretion or disk-wind origin for this feature.
In the optical we find the knots B and B2 in the counter-jet. Knot B has been
observed previously, so we can derive its proper motion of 0.37+-0.01
arcsec/yr. Its electron density is 3000/cm^3, thus the cooling time scale is a
few months only, so the knot needs to be reheated continuously. The shock speed
derived from models of H alpha and forbidden emission lines (FELs) decreased
from 50 km/s in 1999 to 30 km/s in 2011 because the shock front loses energy as
it travels along the jet. Knot B2 is observed at a similar position in 2011 as
knot B was in 1999, but shows a lower ionization fraction and higher mass loss
rate, proving variations in the jet launching conditions.


title: Enhancing the Electrooptic Effect Using Modulation Instability

abstract:
  As electronic operating frequencies increase toward the terahertz regime, new
electrooptic modulators capable of low-voltage high-frequency operation must be
developed to provide the necessary optical interconnects. This letter presents
a new concept that exploits modulation instability to enhance the intrinsically
weak electrooptic effect, \chi^(2). Simulations demonstrate more than 50 times
enhancement of electrooptic effect at millimeter wave frequencies leading to a
substantial reduction in the required modulation voltage.


title:
A logarithmic minimization property of the unitary polar factor in the
  spectral norm and the Frobenius matrix norm

abstract:
  The unitary polar factor $Q=U$ in the polar decomposition of the matrix
$Z=UH$ is the minimizer for both $\| \mathrm{Log}(Q^* Z)\|^2$ and its Hermitian
part $\| \mathrm{sym Log}(Q^* Z)\|^2$ over both $\mathbb{R}$ and $\mathbb{C}$,
for any given invertible matrix $Z$ in $\mathbb{C}^{n\times n}$ and any matrix
logarithm $\mathrm{Log}$, not necessarily the principal logarithm
$\mathrm{log}$. We prove this for the spectral matrix norm in any dimension and
for the Frobenius matrix norm in two and three dimensions. The result shows
that the unitary polar factor is the nearest orthogonal matrix to $Z$ not only
in the normwise sense, but also in a geodesic distance. The derivation is based
on Bhatia's generalization of Bernstein's trace inequality for the matrix
exponential and a new sum of squared logarithms inequality.


title: Determinants of Classical SG-Pseudodifferential Operators

abstract:
  We introduce a generalized trace functional TR in the spirit of Kontsevich
and Vishik's canonical trace for classical SG-pseudodifferential operators on
R^n and suitable manifolds, using a finite-part integral regularization
technique. This allows us to define a zeta-regularized determinant det A for
classical parameter-elliptic SG-operators A of order (\mu,m), with \mu>0,
m\ge0. For m=0, the asymptotics of TR exp(-tA) as t\to 0 and of TR
(\lambda-A)^{-k}$ as |\lambda|\to\infty are derived. For suitable pairs (A,A_0)
we show that det A/det A_0 coincides with the so-called relative determinant
det(A,A_0).


title:
Transverse electric conductivity and dielectric permeability in quantum
  degenerate collisional plasma with variable collision frequency in Mermin's
  approach

abstract:
  Formulas for transverse conductance and dielectric permeability in quantum
degenerate collisional plasma with arbitrary variable collision frequency in
Mermin's approach are deduced. Frequency of collisions of particles depends
arbitrarily on a wave vector. For this purpose the kinetic Shr\"{o}dinger -
Boltzmann equation with collision integral of relaxation type in momentum space
is applied. The case of degenerate Fermi plasma is allocated and investigated.
The special case of frequency of collisions proportional to the module of a
wave vector is considered. The graphic analysis of the real and imaginary parts
of dielectric function is made.


title: Contribution to the theory of Pitman estimators

abstract:
  New inequalities are proved for the variance of the Pitman estimators
(minimum variance equivariant estimators) of \theta constructed from samples of
fixed size from populations F(x-\theta). The inequalities are closely related
to the classical Stam inequality for the Fisher information, its analog in
small samples, and a powerful variance drop inequality. The only condition
required is finite variance of F; even the absolute continuity of F is not
assumed. As corollaries of the main inequalities for small samples, one obtains
alternate proofs of known properties of the Fisher information, as well as
interesting new observations like the fact that the variance of the Pitman
estimator based on a sample of size n scaled by n monotonically decreases in n.
Extensions of the results to the polynomial versions of the Pitman estimators
and a multivariate location parameter are given. Also, the search for
characterization of equality conditions for one of the inequalities leads to a
Cauchy-type functional equation for independent random variables, and an
interesting new behavior of its solutions is described.


title:
Low mass planets in protoplanetary disks with net vertical magnetic
  fields: the Planetary Wake and Gap Opening

abstract:
  We study wakes and gap opening by low mass planets in gaseous protoplanetary
disks threaded by net vertical magnetic fields which drive
magnetohydrodynamical (MHD) turbulence through the magnetorotational instabilty
(MRI), using three dimensional simulations in the unstratified local shearing
box approximation. The wakes, which are excited by the planets, are damped by
shocks similar to the wake damping in inviscid hydrodynamic (HD) disks. Angular
momentum deposition by shock damping opens gaps in both MHD turbulent disks and
inviscid HD disks even for low mass planets, in contradiction to the "thermal
criterion" for gap opening. To test the "viscous criterion", we compared gap
properties in MRI-turbulent disks to those in viscous HD disks having the same
stress, and found that the same mass planet opens a significantly deeper and
wider gap in net vertical flux MHD disks than in viscous HD disks. This
difference arises due to the efficient magnetic field transport into the gap
region in MRI disks, leading to a larger effective \alpha within the gap. Thus,
across the gap, the Maxwell stress profile is smoother than the gap density
profile, and a deeper gap is needed for the Maxwell stress gradient to balance
the planetary torque density. We also confirmed the large excess torque close
to the planet in MHD disks, and found that long-lived density features (termed
zonal flows) produced by the MRI can affect planet migration. The comparison
with previous results from net toroidal flux/zero flux MHD simulations
indicates that the magnetic field geometry plays an important role in the gap
opening process. Overall, our results suggest that gaps can be commonly
produced by low mass planets in realistic protoplanetary disks, and caution the
use of a constant \alpha-viscosity to model gaps in protoplanetary disks.


title:
Complex instruction set computing architecture for performing accurate
  quantum $Z$ rotations with less magic

abstract:
  We present quantum protocols for executing arbitrarily accurate $\pi/2^k$
rotations of a qubit about its $Z$ axis. Reduced instruction set computing
(\textsc{risc}) architectures typically restrict the instruction set to
stabilizer operations and a single non-stabilizer operation, such as
preparation of a "magic" state from which $T = Z(\pi/4)$ gates can be
teleported. Although the overhead required to distill high-fidelity copies of
this magic state is high, the subsequent quantum compiling overhead to realize
$Z$ rotations in a \textsc{risc} architecture can be much greater. We develop a
complex instruction set computing (\textsc{cisc}) architecture whose
instruction set includes stabilizer operations and preparation of magic states
from which $Z(\pi/2^k)$ gates can be teleported, for $2 \leq k \leq
k_{\text{max}}$. This results in a substantial overall reduction in the number
of gates required to achieve a desired gate accuracy for $Z$ rotations. The key
to our construction is a family of shortened quantum Reed-Muller codes of
length $2^{k+2}-1$, whose magic-state distillation threshold shrinks with $k$
but is greater than 0.85% for $k \leq 6$.


title:
Nuclear Physics with Chiral Effective Field Theory: State of the Art and
  Open Challenges

abstract:
  Understanding the properties of atomic nuclei and nuclear dynamics from QCD
remains a major challenge. Complementary to first attempts along these lines
based on lattice QCD, an effective field theory approach has been developed in
the past two decades and applied to a variety of nuclear bound states and
reactions. I outline the foundations of this method, review selected
applications and address some open challenges in this field.


title:
On the Linearization of Second-Order Ordinary Differential Equations to
  the Laguerre Form via Generalized Sundman Transformations

abstract:
  The linearization problem for nonlinear second-order ODEs to the Laguerre
form by means of generalized Sundman transformations (S-transformations) is
considered, which has been investigated by Duarte et al. earlier. A
characterization of these S-linearizable equations in terms of first integral
and procedure for construction of linearizing S-transformations has been given
recently by Muriel and Romero. Here we give a new characterization of
S-linearizable equations in terms of the coefficients of ODE and one auxiliary
function. This new criterion is used to obtain the general solutions for the
first integral explicitly, providing a direct alternative procedure for
constructing the first integrals and Sundman transformations. The effectiveness
of this approach is demonstrated by applying it to find the general solution
for geodesics on surfaces of revolution of constant curvature in a unified
manner.


title:
The Cosmic Evolution of Faint Satellite Galaxies as a Test of Galaxy
  Formation and the Nature of Dark Matter

abstract:
  The standard cosmological model based on cold dark matter (CDM) predicts a
large number of subhalos for each galaxy-size halo. It is well known that
matching the subhalos to the observed properties of luminous satellites of
galaxies in the local universe poses a significant challenge to our
understanding of the astrophysics of galaxy formation. We show that the cosmic
evolution and host mass dependence of the luminosity function of satellites
provides a powerful new diagnostic to disentangle astrophysical effects from
variations in the underlying dark matter mass function. We illustrate this by
comparing the results of recent observations of satellites out to $z=0.8$ based
on Hubble Space Telescope images with the predictions of three different sets
of state-of-the art semi-analytic models with underlying CDM power spectra and
one semi-analytic model with an underlying Warm Dark Matter (WDM) power
spectrum. We find that even though CDM models provide a reasonable fit to the
local luminosity function of satellites around galaxies comparable or slightly
larger than the Milky Way, they do not reproduce the data as well for different
redshift and host galaxy stellar mass. This tension indicates that further
improvements are likely to be needed in the description of star formation if
the models are to be reconciled with the data. The WDM model matches the
observed mass dependence and redshift evolution of satellite galaxies more
closely than any of the CDM models, indicating that a modification of the
underlying power spectrum may offer an alternative solution to this tension. We
conclude by presenting predictions for the color magnitude relation of
satellite galaxies to demonstrate how future observations will be able to
further distinguish between these models and help constrain baryonic and
non-baryonic physics.


title:
Incorporating molecular data in fungal systematics: a guide for aspiring
  researchers

abstract:
  The last twenty years have witnessed molecular data emerge as a primary
research instrument in most branches of mycology. Fungal systematics, taxonomy,
and ecology have all seen tremendous progress and have undergone rapid,
far-reaching changes as disciplines in the wake of continual improvement in DNA
sequencing technology. A taxonomic study that draws from molecular data
involves a long series of steps, ranging from taxon sampling through the
various laboratory procedures and data analysis to the publication process. All
steps are important and influence the results and the way they are perceived by
the scientific community. The present paper provides a reflective overview of
all major steps in such a project with the purpose to assist research students
about to begin their first study using DNA-based methods. We also take the
opportunity to discuss the role of taxonomy in biology and the life sciences in
general in the light of molecular data. While the best way to learn molecular
methods is to work side by side with someone experienced, we hope that the
present paper will serve to lower the learning threshold for the reader.


title: HST Fine Guidance Sensor Parallaxes for Four Classical Novae

abstract:
  We have used data obtained with the Fine Guidance Sensors on the Hubble Space
Telescope to derive precise astrometric parallaxes for four classical novae:
V603 Aql, DQ Her, GK Per, and RR Pic. All four objects exceeded the Eddington
limit at visual maximum. Re-examination of the original light curve data for
V603 Aql and GK Per has led us to conclude that their visual maxima were
slightly brighter than commonly assumed. With known distances, we examine the
various maximum magnitude--rate of decline (MMRD) relationships that have been
established for classical novae. We find that these four objects show a similar
level of scatter about these relationships as seen in larger samples of novae
whose distances were determined using indirect techniques. We also examine the
nebular expansion parallax method, and find that it fails for three of the four
objects. In each case it was possible to find an explanation for the failure of
that technique to give precise distance estimates. DQ Her appears to suffer
from an anomalously high extinction when compared to field stars on its sight
line. We suggest that this is likely due to local material, which may also be
the source of the IRAS detections of this object.


title: Cosmic Ray transport in turbulent magnetic field

abstract:
  Cosmic ray (CR) transport and acceleration is determined by the properties of
magnetic turbulence. Recent advances in MHD turbulence call for revisions in
the paradigm of cosmic ray transport. We use the models of magnetohydrodynamic
turbulence that were tested in numerical simulation, in which turbulence is
injected at large scale and cascades to to small scales. We shall address the
issue of the transport of CRs, both parallel and perpendicular to the magnetic
field. We shall demonstrate compressible fast modes are dominant cosmic ray
scatterer from both quasilinear and nonlinear theories. We shall also show that
the self-generated wave growth by CRs are constrained by preexisting turbulence
and discuss the process in detail in the context of shock acceleration at
supernova remnants and their implications. In addition, we shall dwell on the
nonlinear growth of kinetic gyroresonance instability of cosmic rays induced by
large scale compressible turbulence. This gyroresonance of cosmic rays on
turbulence is demonstrated an important scattering mechanism in addition to
direct interaction with the compressible turbulence. The feedback of the
instability on large scale turbulence should be included in future simulations.


title: Permutation-invariant quantum codes

abstract:
  A quantum code is a subspace of a Hilbert space of a physical system chosen
to be correctable against a given class of errors, where information can be
encoded. Ideally, the quantum code lies within the ground space of the physical
system. When the physical model is the Heisenberg ferromagnet in the absence of
an external magnetic field, the corresponding ground-space contains all
permutation-invariant states. We use techniques from combinatorics and operator
theory to construct families of permutation-invariant quantum codes. These
codes have length proportional to $t^2$; one family of codes perfectly corrects
arbitrary weight $t$ errors, while the other family of codes approximately
correct $t$ spontaneous decay errors. The analysis of our codes' performance
with respect to spontaneous decay errors utilizes elementary matrix analysis,
where we revisit and extend the quantum error correction criterion of Knill and
Laflamme, and Leung, Chuang, Nielsen and Yamamoto.


title:
Physical origin of satellite in photoemission of doped graphene: An
  ab-initio GW plus cumulant study

abstract:
  We calculate the photoemission spectra of suspended and epitaxial doped
graphene using an ab initio cumulant expansion of the Green's function based on
the GW self-energy. Our results are compared to experiment and to standard GW
calculations. For doped graphene on a silicon carbide substrate, we find, in
contrast to earlier calculations, that the spectral function from GW only does
not reproduce experimental satellite properties. However, ab initio GW plus
cumulant theory combined with an accurate description of the substrate
screening results in good agreement with experiment, but gives no plasmaron
(i.e., no extra well-defined excitation satisfying Dyson's equation).


title: Special Values of Anticyclotomic L-functions Modulo \lambda

abstract:
  The purpose of this article is to generalize some results of Vatsal on
studying the special values of Rankin-Selberg L-functions in an anticyclotomic
$\mathbb{Z}_{p}$-extension. Let $g$ be a cuspidal Hilbert modular form of
parallel weight (2,...,2) and level $\mathcal{N}$ over a totally real field F,
and let K/F be a totally imaginary quadratic extension of relative discriminant
$\mathcal{D}$. We study the $l$-adic valuation of the special values
$L(g,\chi,\frac{1}{2})$ as \chi varies over the ring class characters of K of
$\mathcal{P}$-power conductor, for some fixed prime ideal $\mathcal{P}$. We
prove our results under the only assumption that the prime to $\mathcal{P}$
part of $\mathcal{N}$ is relatively prime to $\mathcal{D}$.


title:
Exploiting the Past to Reduce Delay in CSMA Scheduling: A High-order
  Markov Chain Approach

abstract:
  Recently several CSMA algorithms based on the Glauber dynamics model have
been proposed for multihop wireless scheduling, as viable solutions to achieve
the throughput optimality, yet are simple to implement. However, their delay
performances still remain unsatisfactory, mainly due to the nature of the
underlying Markov chains that imposes a fundamental constraint on how the link
state can evolve over time. In this paper, we propose a new approach toward
better queueing and delay performance, based on our observation that the
algorithm needs not be Markovian, as long as it can be implemented in a
distributed manner, achieve the same throughput optimality, while offering far
better delay performance for general network topologies. Our approach hinges
upon utilizing past state information observed by local link and then
constructing a high-order Markov chain for the evolution of the feasible link
schedules. We show in theory and simulation that our proposed algorithm, named
delayed CSMA, adds virtually no additional overhead onto the existing
CSMA-based algorithms, achieves the throughput optimality under the usual
choice of link weight as a function of local queue length, and also provides
much better delay performance by effectively `de-correlating' the link state
process (thus removing link starvation) under any arbitrary network topology.
From our extensive simulations we observe that the delay under our algorithm
can be often reduced by a factor of 20 over a wide range of scenarios, compared
to the standard Glauber-dynamics-based CSMA algorithm.


title:
Finding extraterrestrial life using ground-based high-resolution
  spectroscopy

abstract:
  Exoplanet observations promise one day to unveil the presence of
extraterrestrial life. Atmospheric compounds in strong chemical disequilibrium
would point to large-scale biological activity just as oxygen and methane do in
the Earth's atmosphere. The cancellation of both the Terrestrial Planet Finder
and Darwin missions means that it is unlikely that a dedicated space telescope
to search for biomarker gases in exoplanet atmospheres will be launched within
the next 25 years. Here we show that ground-based telescopes provide a strong
alternative for finding biomarkers in exoplanet atmospheres through transit
observations. Recent results on hot Jupiters show the enormous potential of
high-dispersion spectroscopy to separate the extraterrestrial and telluric
signals making use of the Doppler shift of the planet. The transmission signal
of oxygen from an Earth-twin orbiting a small red dwarf star is only a factor 3
smaller than that of carbon monoxide recently detected in the hot Jupiter tau
Bootis b, albeit such a star will be orders of magnitude fainter. We show that
if Earth-like planets are common, the planned extremely large telescopes can
detect oxygen within a few dozen transits. Ultimately, large arrays of
dedicated flux collector telescopes equipped with high-dispersion spectrographs
can provide the large collecting area needed to perform a statistical study of
life-bearing planets in the solar neighborhood.


title:
Electronic phase diagram of high temperature copper oxide
  superconductors

abstract:
  In order to understand the origin of high-temperature superconductivity in
copper oxides, we must understand the normal state from which it emerges. Here,
we examine the evolution of the normal state electronic excitations with
temperature and carrier concentration in Bi2Sr2CaCu2O8 using angle-resolved
photoemission. In contrast to conventional superconductors, where there is a
single temperature scale Tc separating the normal from the superconducting
state, the high- temperature superconductors exhibit two additional temperature
scales. One is the pseudogap scale T*, below which electronic excitations
exhibit an energy gap. The second is the coherence scale Tcoh, below which
sharp spectral features appear due to increased lifetime of the excitations. We
find that T* and Tcoh are strongly doping dependent and cross each other near
optimal doping. Thus the highest superconducting Tc emerges from an unusual
normal state that is characterized by coherent excitations with an energy gap.


title:
Quantum-Confinement-Induced Magnetism in LaNiO$_3$-LaMnO$_3$
  Superlattices

abstract:
  The emergence of magnetic reconstructions at the interfaces of oxide
heterostructures are often explained via subtle modifications in the electronic
densities, exchange couplings, or strain. Here an additional possible route for
induced magnetism is studied in the context of the
(LaNiO$_3$)$_n$/(LaMnO$_3$)$_n$ superlattices using a hybrid tight-binding
model. In the LaNiO$_3$ region, the induced magnetizations decouple from the
intensity of charge leakage from Mn to Ni, but originate from the spin-filtered
quantum confinement present in these nanostructures. In general, the induced
magnetization is the largest for the (111)-stacking and the weakest for the
(001)-stacking superlattices, results compatible with the exchange bias effects
reported by Gibert et al. Nat. Mater. 11, 195 (2012).


title: Magnetic Reconnection in Turbulent Plasmas and Gamma Ray Bursts

abstract:
  We discuss how the model of magnetic reconnection in the presence of
turbulence proposed inLazarian & Vishniac 1999 makes the reconnection rate
independent either of resistivity or microscopic plasma effects, but determined
entirely by the magnetic field line wandering induced by turbulence. We explain
that the model accounts for both fast and slow regimes of reconnection and that
this property naturally induces flares of reconnection in low beta plasma
environments. In addition, we show that the model involves volume reconnection
which can convert a substantial part of the energy into energetic particles. It
is important that the reconnection induces an efficient acceleration of the
first order Fermi type. Finally, we relate the properties of the reconnection
with the observed properties of gamma ray bursts and provide evidence
supporting the explanation of gamma ray bursts based on energy release via
reconnection.


title: Finsler Metrics with Bounded Cartan Torsions

abstract:
  The norm of Cartan torsion plays an important role for studying of immersion
theory in Finsler geometry. Indeed, Finsler manifold with unbounded Cartan
torsion can not be isometrically imbedded into any Minkowski space. In this
paper, we find two subclasses of (?, ?)-metrics which have bounded Cartan
torsion. Then, we give two subclasses of (?, ?)-metrics whose bound on the
Cartan torsions are independent of the norm of ?.


title: On Generalized m-th Root Finsler Metrics

abstract:
  In this paper, we characterize locally dually flat generalized m-th root
Finsler metrics. Then we find a condition under which a generalized m-th root
metric is projectively related to a m-th root metric. Finally, we prove that if
a generalized m-th root metric is conformal to a m-th root metric, then both of
them reduce to Riemannian metrics.


title: On Twisted Products Finsler Manifolds

abstract:
  On the product of two Finsler manifolds M1 M2, we consider the twisted metric
F which is construct by using Finsler metrics F1 and F2 on the manifolds M1 and
M2, respectively. We introduce horizontal and vertical distributions on twisted
product Finsler manifold and study Creducible and semi-C-reducible properties
of this manifold. Then we obtain the Riemannian curvature and some of
non-Riemannian curvatures of the twisted product Finsler manifold such as
Berwald curvature, mean Berwald curvature and we find the relations between
these objects and their corresponding objects on M1 and M2. Finally, we study
locally dually flat twisted product Finsler manifold.


title:
The frequency-dependence of nonlinear conductivity in disordered
  systems: an analytically solvable model

abstract:
  For the hopping dynamics in a one-dimensional model, containing energy and
barrier disorder, we determine the linear and nonlinear response to an external
field for arbitrary external frequencies. The calculation is performed in
analytical terms. We systematically analyze the parameter space and find three
different regimes, corresponding to qualitatively different frequency
dependencies of the nonlinear response. Two regimes agree with the results of
recent conductivity experiments on inorganic ion conductors and ionic liquids,
respectively. The ratio of the nonlinear and linear conductivity in the
dc-regime can be explicitly expressed in terms of the disorder parameters. As a
generic feature the nonlinear conductivity displays a minimum as a function of
frequency which can be identified with forward-backward dynamics in a
double-well potential. The magnitude and sign of the nonlinear conductivity
around the minimum is a measure of the disorder, inherent in this model.
Surprisingly, the frequency of the minimum is hardly influenced by the
disorder.


title: Interband Tunneling in 2D Crystal Semiconductors

abstract:
  Interband quantum tunneling of electrons in semiconductors is of intense
recent interest as the underlying transport mechanism in tunneling field-effect
transistors. Such transistors can potentially perform electronic switching with
lower energy than their conventional counterparts. The recent emergence of
2-dimensional semiconducting crystals provides a new material platform for
realizing such devices. In this work, we derive an analytical expression for
understanding tunneling current flow in 2D crystal semiconductors. We apply the
results to a range of 2D crystal semiconductors, and compare it with tunneling
currents in 3D semiconductors. We also discuss the implications for tunneling
devices.


title: Measuring Black Hole Spin using X-ray Reflection Spectroscopy

abstract:
  I review the current status of X-ray reflection (a.k.a. broad iron line)
based black hole spin measurements. This is a powerful technique that allows us
to measure robust black hole spins across the mass range, from the stellar-mass
black holes in X-ray binaries to the supermassive black holes in active
galactic nuclei. After describing the basic assumptions of this approach, I lay
out the detailed methodology focusing on "best practices" that have been found
necessary to obtain robust results. Reflecting my own biases, this review is
slanted towards a discussion of supermassive black hole (SMBH) spin in active
galactic nuclei (AGN). Pulling together all of the available XMM-Newton and
Suzaku results from the literature that satisfy objective quality control
criteria, it is clear that a large fraction of SMBHs are rapidly-spinning,
although there are tentative hints of a more slowly spinning population at high
(M>5*10^7Msun) and low (M<2*10^6Msun) mass. I also engage in a brief review of
the spins of stellar-mass black holes in X-ray binaries. In general,
reflection-based and continuum-fitting based spin measures are in agreement,
although there remain two objects (GROJ1655-40 and 4U1543-475) for which that
is not true. I end this review by discussing the exciting frontier of
relativistic reverberation, particularly the discovery of broad iron line
reverberation in XMM-Newton data for the Seyfert galaxies NGC4151, NGC7314 and
MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk
reflection, this detection of reverberation demonstrates that future large-area
X-ray observatories such as LOFT will make tremendous progress in studies of
strong gravity using relativistic reverberation in AGN.


title:
Pavlov's dog associative learning demonstrated on synaptic-like organic
  transistors

abstract:
  In this letter, we present an original demonstration of an associative
learning neural network inspired by the famous Pavlov's dogs experiment. A
single nanoparticle organic memory field effect transistor (NOMFET) is used to
implement each synapse. We show how the physical properties of this dynamic
memristive device can be used to perform low power write operations for the
learning and implement short-term association using temporal coding and spike
timing dependent plasticity based learning. An electronic circuit was built to
validate the proposed learning scheme with packaged devices, with good
reproducibility despite the complex synaptic-like dynamic of the NOMFET in
pulse regime.


title:
Nonperturbative resummation of de Sitter infrared logarithms in the
  large-N limit

abstract:
  We study the O(N) scalar field theory with quartic self-coupling in de Sitter
space. When the field is light in units of the expansion rate, perturbative
methods break down at very low momenta due to large infrared logarithmic terms.
Using the nonperturbative large-N limit, we compute the four-point vertex
function in the deep infrared regime. The resummation of an infinite series of
perturbative (bubble) diagrams leads to a modified power law which is analogous
to the generation of an anomalous dimension in critical phenomena. We discuss
in detail the role of high momentum (subhorizon) modes, including the issue of
renormalization, and show that they influence the dynamics of infrared
(superhorizon) modes only through a constant renormalization factor. This
provides an explicit example of effective decoupling between high and low
energy physics in an expanding space-time.


title:
Assessment of urban ecosystem resilience using the efficiency of hybrid
  social-physical complex networks

abstract:
  One of the most important tasks of urban and hazard planning is to mitigate
the damages and minimize the costs of the recovery process after catastrophic
events. The rapidity and the efficiency of the recovery process are commonly
referred to as resilience. Despite the problem of resilience quantification has
received a lot of attention, a mathematical definition of the resilience of an
urban community, which takes into account the social aspects of a urban
environment, has not yet been identified. In this paper we provide and test a
methodology for the assessment of urban resilience to catastrophic events which
aims at bridging the gap between the engineering and the ecosystem approaches
to resilience. We propose to model a urban system by means of different hybrid
social-physical complex networks, obtained by enriching the urban street
network with additional information about the social and physical constituents
of a city, namely citizens, residential buildings and services. Then, we
introduce a class of efficiency measures on these hybrid networks, inspired by
the definition of global efficiency given in complex network theory, and we
show that these measures can be effectively used to quantify the resilience of
a urban system, by comparing their respective values before and after a
catastrophic event and during the reconstruction process. As a case study, we
consider simulated earthquakes in the city of Acerra, Italy, and we use these
efficiency measures to compare the ability of different reconstruction
strategies in restoring the original performance of the urban system.


title: Magnetic Field Measurement with Ground State Alignment

abstract:
  Observational studies of magnetic fields are crucial. We introduce a process
"ground state alignment" as a new way to determine the magnetic field direction
in diffuse medium. The alignment is due to anisotropic radiation impinging on
the atom/ion. The consequence of the process is the polarization of spectral
lines resulting from scattering and absorption from aligned atomic/ionic
species with fine or hyperfine structure. The magnetic field induces precession
and realign the atom/ion and therefore the polarization of the emitted or
absorbed radiation reflects the direction of the magnetic field. The atoms get
aligned at their low levels and, as the life-time of the atoms/ions we deal
with is long, the alignment induced by anisotropic radiation is susceptible to
extremely weak magnetic fields ($1{\rm G}\gtrsim B\gtrsim 10^{-15}$G). In fact,
the effects of atomic/ionic alignment were studied in the laboratory decades
ago, mostly in relation to the maser research. Recently, the atomic effect has
been already detected in observations from circumstellar medium and this is a
harbinger of future extensive magnetic field studies. A unique feature of the
atomic realignment is that they can reveal the 3D orientation of magnetic
field. In this article, we shall review the basic physical processes involved
in atomic realignment. We shall also discuss its applications to
interplanetary, circumstellar and interstellar magnetic fields. In addition,
our research reveals that the polarization of the radiation arising from the
transitions between fine and hyperfine states of the ground level can provide a
unique diagnostics of magnetic fields in the Epoch of Reionization.

categories: astro-ph.GA astro-ph.EP astro-ph.IM astro-ph.SR


title: Critical phenomena in the dynamical visibility graph

abstract:
  We have investigated the time series by the mapping them to the complex
network. We have studied the behavior of the relative number of clusters in
dynamic visibility graphs near the critical value of the angle of view. Time
series of different nature both artificial and experimental were numerically
investigated. In all cases, the dependence of the relative number of clusters
on the proximity to the critical angle of view had a power law behavior. Thus,
it was shown that there is a similarity between the behavior of the relative
number of clusters and the order parameter in the second-order phase transition
theory and percolation theory. Each time series is characterized by its own
value of the critical index - an analog of the critical index in second-order
phase transition theory.


title:
Nonlinear noise excitation of intermittent stochastic PDEs and the
  topology of LCA groups

abstract:
  Consider the stochastic heat equation
$\partial_tu=\mathscr{L}u+\lambda\sigma(u)\xi$, where $\mathscr{L}$ denotes the
generator of a L\'{e}vy process on a locally compact Hausdorff Abelian group
$G$, $\sigma:\mathbf{R}\to\mathbf{R}$ is Lipschitz continuous, $\lambda\gg1$ is
a large parameter, and $\xi$ denotes space-time white noise on
$\mathbf{R}_+\times G$. The main result of this paper contains a near-dichotomy
for the (expected squared) energy $\mathrm{E}(\|u_t\|_{L^2(G)}^2)$ of the
solution. Roughly speaking, that dichotomy says that, in all known cases where
$u$ is intermittent, the energy of the solution behaves generically as
$\exp\{\operatorname {const}\cdot\,\lambda^2\}$ when $G$ is discrete and
$\ge\exp\{\operatorname {const}\cdot\,\lambda^4\}$ when $G$ is connected.


title: Postcranial pneumaticity in dinosaurs and the origin of the avian lung

abstract:
  In birds, diverticula of the lungs and air sacs pneumatize specific regions
of the postcranial skeleton. Relationships among pulmonary components and
skeletal regions they pneumatize allow inferences about pulmonary anatomy in
non-avian dinosaurs. Fossae, foramina and chambers in the postcranial skeletons
of pterosaurs and saurischian dinosaurs are diagnostic for pneumaticity. In
basal saurischians only the cervical skeleton is pneumatized, by cervical air
sacs. In more derived saurischians pneumatization of posterior dorsal, sacral,
and caudal vertebrae indicates abdominal air sacs. Abdominal air sacs in
sauropods are also indicated by a pneumatic hiatus (a gap in vertebral
pneumatization) in Haplocanthosaurus. Minimally, saurischians had dorsally
attached diverticular lungs plus anterior and posterior air sacs, and all the
pulmonary prerequisites for flow-through lung ventilation like that of birds.
Pneumaticity reduced skeletal mass in saurischians. I propose the Air Space
Proportion (ASP) as a measure of proportional volume of air in pneumatic bones.
The mean ASP of a sample of sauropod and theropod vertebrae is 0.61, so on
average, air occupied more than half the volume of these vertebrae. In
Diplodocus, pneumatization lightened the living animal by 7-10 percent, and
that does not include extraskeletal diverticula, air sacs, lungs, or trachea.
If all these air reservoirs included, the specific gravity of Diplodocus is
0.80, higher than published values for birds but lower than those for squamates
and crocodilians. Pneumatization of cervical vertebrae facilitated evolution of
long necks in sauropods. Necks longer than nine meters evolved at least four
times, in mamenchisaurs, diplodocids, brachiosaurids, and titanosaurs.
Increases in the number of cervical vertebrae, their proportional lengths, and
their internal complexity occurred in parallel in most of these lineages.


title: Adaptive Crowdsourcing Algorithms for the Bandit Survey Problem

abstract:
  Very recently crowdsourcing has become the de facto platform for distributing
and collecting human computation for a wide range of tasks and applications
such as information retrieval, natural language processing and machine
learning. Current crowdsourcing platforms have some limitations in the area of
quality control. Most of the effort to ensure good quality has to be done by
the experimenter who has to manage the number of workers needed to reach good
results.
  We propose a simple model for adaptive quality control in crowdsourced
multiple-choice tasks which we call the \emph{bandit survey problem}. This
model is related to, but technically different from the well-known multi-armed
bandit problem. We present several algorithms for this problem, and support
them with analysis and simulations. Our approach is based in our experience
conducting relevance evaluation for a large commercial search engine.


title: A Superdimensional Dual-covariant Field Theory

abstract:
  An approach to a Unified Field Theory (UFT) is developed as an attempt to
establish unification of the Theory of Quantum Fields (QFT) and General Theory
of Relativity (GTR) on the background of a covariant differential calculus. A
dual State Vector field (DSV)consisting of covariant and contravariant
N-component functions of variables of a N-dimensional unified manifod (UM)is
introduced to represents matter. DSV is supposed to transform in a way distinct
from that of the differentials of the UM variables. Consequently, the hybrid
tensors and a hybrid affine tensor (Dynamic Connection, DC) are introduced. The
hybrid curvature form (HCF) is introduced as a covariant derivative of DC. A
system of covariant Euler-Lagrange (EL) equations for DSV, DC, and a twin
couple of the triadic hybrid tensors (Split Metric, SM)is derived. A scalar
Lagrangian form is composed based on a set of principles suited for UFT,
including the homogeneity in the UM space, differential irreducibility and
scale invariance. The type of the manifold geometry is not specified in
advance, in neither local (signature) nor regional (topology) aspects.
Equations for DSV play role of the Schroedinger-Dirac equation in space of UM.
By the correspondent EL equations, DC and SM are connected to DSV and become
responsible for the non-linear features of the system i.e. interactions. In
this paper we mark breaking of a background paradigm of the modern QFT, the
superposition principle. The issue of the UM-MF dimensionality will be
addressed, and relations to the principles and methodology of QFT and GTR will
be discussed.


title: The Atomic Hydrogen Cloud in the Saturnian System

abstract:
  The Voyager flyby observations revealed that a very broad doughnut shaped
distribution of the hydrogen atoms existed in the Saturnian magnetosphere.
Recent Cassini observations confirmed the local-time asymmetry but also showed
the hydrogen cloud density increases with decreasing distance to Saturn. The
origin of the atomic hydrogen cloud has been debated ever since. Therefore, we
have carried out a global investigation of the atomic hydrogen cloud taking
into account all possible sources: 1) the Saturnian atmosphere, 2) the H2
atmosphere of main rings, 3) Enceladus H2O and OH torus, 4) Titan H2 torus and
5) the atomic hydrogen directly escaping from Titan. We show that the H
ejection velocity and angle distribution are modified by collisions of the hot
H, produced by electron-impact dissociation of H2, with the ambient atmospheric
H2 and H. This in turn affects the morphology of the escaping hydrogen as does
the morphology of the ionospheric electron distribution. That Saturn atmosphere
is an important source is suggested by the fact that the H cloud peaks well
below the ring plane, a feature that, so far, we can not reproduce by the
dissociation of the ring H2 atmosphere or other proposed sources. Our
simulations show that H directly escaping from Titan is a major contribution in
the outer magnetosphere. The morphology of Titan H torus, shaped by the solar
radiation pressure and the Saturnian oblateness, can account for the local time
asymmetry near Titan orbit. Dissociation of H2O and OH in the Enceladus torus
contributes inside ~5 RS, but dissociation of Titan H2 torus does not due to
the significant energy released. The total number of H observed by Cassini
inside 5 RS: our modeling results suggest ~20% from dissociation in the
Enceladus torus, ~10% from dissociation of ring H2 atmosphere, and ~50% from
Titan H torus implying that ~20% comes from the Saturnian atmosphere.


title: Generalized Isotropic Berwald Manifolds

abstract:
  In this paper, we construct a new class of Finsler manifolds called
generalized isotropic Berwald manifolds which is an extension of the class of
isotropic Berwald manifolds. We prove that every generalized isotropic Berwald
manifold is a generalized Douglas-Weyl manifold. On a compact generalized
isotropic Berwald manifold, we show that the notions of stretch and Landsberg
curvatures are equivalent. Then we prove that on these manifolds, a Finsler
metric is R-quadratic if and only if it is a stretch metric with vanishing E
-curvature. Finally, we determine the flag curvature of generalized isotropic
Berwald manifold with scalar flag curvature.


title: On Cartan Spaces with m-th Root Metrics

abstract:
  In this paper, we define some non-Riemannian curvature properties for Cartan
spaces. We consider Cartan space with the m-th root metric. We prove that every
m-th root Cartan space of isotropic Landsberg curvature, or isotropic mean
Landsberg curvature, or isotropic mean Berwald curvature reduces to a
Landsberg, weakly Landsberg and weakly Berwald space, respectively. Then we
show that m-th root Cartan space of almost vanishing H-curvature satisfies H =
0.


title: IAXO - The International Axion Observatory

abstract:
  The International Axion Observatory (IAXO) is a next generation axion
helioscope aiming at a sensitivity to the axion-photon coupling of a few
10^{-12} GeV^{-1}, i.e. 1-1.5 orders of magnitude beyond sensitivities achieved
by the currently most sensitive axion helioscope, the CERN Axion Solar
Telescope (CAST). Crucial factors in improving the sensitivity for IAXO are the
increase of the magnetic field volume together with the extensive use of x-ray
focusing optics and low background detectors, innovations already successfully
tested at CAST. Electron-coupled axions invoked to explain the white dwarf
cooling, relic axions, and a large variety of more generic axion-like particles
(ALPs) along with other novel excitations at the low-energy frontier of
elementary particle physics could provide additional physics motivation for
IAXO.


title:
Disentangling the effects of geographic and ecological isolation on
  genetic differentiation

abstract:
  Populations can be genetically isolated both by geographic distance and by
differences in their ecology or environment that decrease the rate of
successful migration. Empirical studies often seek to investigate the
relationship between genetic differentiation and some ecological variable(s)
while accounting for geographic distance, but common approaches to this problem
(such as the partial Mantel test) have a number of drawbacks. In this article,
we present a Bayesian method that enables users to quantify the relative
contributions of geographic distance and ecological distance to genetic
differentiation between sampled populations or individuals. We model the allele
frequencies in a set of populations at a set of unlinked loci as spatially
correlated Gaussian processes, in which the covariance structure is a
decreasing function of both geographic and ecological distance. Parameters of
the model are estimated using a Markov chain Monte Carlo algorithm. We call
this method Bayesian Estimation of Differentiation in Alleles by Spatial
Structure and Local Ecology (BEDASSLE), and have implemented it in a
user-friendly format in the statistical platform R. We demonstrate its utility
with a simulation study and empirical applications to human and teosinte
datasets.


title:
CR Structures and Twisting Vacuum Spacetimes with Two Killing Vectors
  and Cosmological Constant: Type II and More Special

abstract:
  Based on the CR formalism of algebraically special spacetimes by Hill,
Lewandowski and Nurowski, we derive a nonlinear system of two real ODEs, of
which the general solution determines a twisting type II (or more special)
vacuum spacetime with two Killing vectors (commuting or not) and at most seven
real parameters in addition to the cosmological constant Lambda. To demonstrate
a broad range of interesting spacetimes that these ODEs can capture, special
solutions of various Petrov types are presented and described as they appear in
this approach. They include Kerr-NUT, Kerr and Debney/Demia\'{n}ski's type II,
Lun's type II and III (subclasses of Held-Robinson), MacCallum and Siklos' type
III (Lambda<0), and the type N solutions (Lambda<>0) we found in an earlier
paper, along with a new class of type II solutions as a nontrivial limit of
Kerr and Debney's type II solutions. Also, we discuss a situation in which the
two ODEs can be reduced to one. However, constructing the general solution
still remains an open problem.


title: Practical corollaries of transverse Ward-Green-Takahashi identities

abstract:
  The gauge principle is fundamental in formulating the Standard Model.
Fermion--gauge-boson couplings are the inescapable consequence and the primary
determining factor for observable phenomena. Vertices describing such couplings
are simple in perturbation theory and yet the existence of strong-interaction
bound-states guarantees that many phenomena within the Model are
nonperturbative. It is therefore crucial to understand how dynamics dresses the
vertices and thereby fundamentally alters the appearance of
fermion--gauge-boson interactions. We consider the coupling of a
dressed-fermion to an Abelian gauge boson, and describe a unified treatment and
solution of the familiar longitudinal Ward-Green-Takahashi identity and its
less well known transverse counterparts. Novel consequences for the
dressed-fermion--gauge-boson vertex are exposed.


title: Improved Methods for Hypergraphs

abstract:
  We introduce a new background field method for N=2 superspace. (We treat
projective hyperspace, but similar remarks apply for the harmonic case.) In
analogy to N=1, background gauge fields are in the real representation, so the
lowest-dimension potentials are spinor and the usual non-renormalization
theorems are manifest. Another consequence is that the R-coordinates disappear
from the effective action.


title: Impact of tensor force on \beta-decay of magic and semi-magic nuclei

abstract:
  Effect of the tensor force on $\beta$?-decay is studied in the framework of
the proton-neutron random-phase-approximation (RPA) with the Skyrme force. The
investigation is performed for even-even semi-magic and magic nuclei,
$^{34}$Si, $^{68}$, $^{78}$Ni and $^{132}$Sn. The tensor correlation induces
strong impact on low-lying Gamow-Teller state. In particular, it improves the
?$\beta$-decay half-lives. $Q$ and $ft$ values are also investigated and
compared with experimental data.


title: Bounded analytic maps, Wall fractions and ABC flow

abstract:
  In this work we study the qualitative properties of real analytic bounded
maps defined in the infinite complex strip. The main tool is approximation by
continued g-fractions of Wall. As an application, the ABC flow system is
considered which is essential to the origin of the solar magnetic field.


title: Decoupling of DeGiorgi-type systems via multi-marginal optimal transport

abstract:
  We exhibit a surprising relationship between elliptic gradient systems of
PDEs, multi-marginal Monge-Kantorovich optimal transport problem, and
multivariable Hardy-Littlewood inequalities. We show that the notion of an
orientable elliptic system, conjectured in [6] to imply that (in low
dimensions) solutions with certain monotonicity properties are essentially
1-dimensional, is equivalent to the definition of a compatible cost function,
known to imply uniqueness and structural results for optimal measures to
certain Monge-Kantorovich problems [11]. Orientable nonlinearities and
compatible cost functions turned out to be also related to submodular
functions, which appear in rearrangement inequalities of Hardy-Littlewood type.
We use this equivalence to establish a decoupling result for certain solutions
to elliptic PDEs and show that under the orientability condition, the
decoupling has additional properties, due to the connection to optimal
transport.


title: Constructing commutative semifields of square order

abstract:
  The projection construction has been used to construct semifields of odd
characteristic using a field and a twisted semifield [Commutative semifields
from projection mappings, Designs, Codes and Cryptography, 61 (2011),
187--196]. We generalize this idea to a projection construction using two
twisted semifields to construct semifields of odd characteristic. Planar
functions and semifields have a strong connection so this also constructs new
planar functions.


title: Counting invariant components of hyperelliptic translation surfaces

abstract:
  The flow in a fixed direction on a translation surface S determines a
decomposition of S into closed invariant sets, each of which is either periodic
or minimal. We study this decomposition for translation surfaces in the
hyperelliptic connected components $\mathcal{H}^{hyp}(2g-2)$ and
$\mathcal{H}^{hyp}(g-1,g-1)$ of the corresponding strata of the moduli space of
translation surfaces. Specifically, we characterize the pairs of nonnegative
integers (p,m) for which there exists a translation surface in
$\mathcal{H}^{hyp}(2g-2)$ or $\mathcal{H}^{hyp}(g-1,g-1)$ with precisely p
periodic components and m minimal components. This extends results by Naveh
([Naveh08]), who obtained tight upper bounds on the numbers of minimal
components and invariant components a translation surface in any given stratum
may have. Analogous results for the other connected components of moduli space
are forthcoming.


title: StructBoost: Boosting Methods for Predicting Structured Output Variables

abstract:
  Boosting is a method for learning a single accurate predictor by linearly
combining a set of less accurate weak learners. Recently, structured learning
has found many applications in computer vision. Inspired by structured support
vector machines (SSVM), here we propose a new boosting algorithm for structured
output prediction, which we refer to as StructBoost. StructBoost supports
nonlinear structured learning by combining a set of weak structured learners.
As SSVM generalizes SVM, our StructBoost generalizes standard boosting
approaches such as AdaBoost, or LPBoost to structured learning. The resulting
optimization problem of StructBoost is more challenging than SSVM in the sense
that it may involve exponentially many variables and constraints. In contrast,
for SSVM one usually has an exponential number of constraints and a
cutting-plane method is used. In order to efficiently solve StructBoost, we
formulate an equivalent $ 1 $-slack formulation and solve it using a
combination of cutting planes and column generation. We show the versatility
and usefulness of StructBoost on a range of problems such as optimizing the
tree loss for hierarchical multi-class classification, optimizing the Pascal
overlap criterion for robust visual tracking and learning conditional random
field parameters for image segmentation.


title:
On the macroscopic verifications of Klein's theorem and the proof of
  $E_0=mc^2$

abstract:
  Alternative verifications of Klein's theorem and the proof of $E_0=mc^2$, for
a relativistic macroscopic body are presented, using models with boundary
conditions of varying complexity, together with some refinements for the case
containing electromagnetic radiation for the simplest model. The robustness of
these models to the final result of $E_0=mc^2$, attests to the minor role
played by the Poincar\'e type stresses introduced in some of these models for
mechanical stability. Finally we caution the reader that while internal
consistency of the $E_0=mc^2$ relation for a macroscopic body in special
relativity is proved, it does not in any way furnish a proof of the relation
for a single point particle, for this would imply that one is able to prove the
postulates of special relativity from the premises of the theory itself.


title:
C-axis optical conductivity from the Yang-Rice-Zhang model of the
  underdoped cuprates

abstract:
  The c-axis optical response of the underdoped cuprates is qualitatively
different from its in-plane counterpart. The features of the pseudogap show
themselves more prominently in the c-axis than in-plane. We compute both the
c-axis and in-plane optical conductivity using the Yang-Rice-Zhang model of the
underdoped cuprates. This model combined with coherent interlayer tunnelling is
enough to explain the qualitative differences between the in-plane and c-axis
data. We show how pseudogap features manifest themselves in the infrared and
microwave conductivity within this model.