title:
Recurrence Relations for Finite-Temperature Correlators via
  AdS$_{2}$/CFT$_{1}$

abstract:
  This note is aimed at presenting a new algebraic approach to momentum-space
correlators in conformal field theory. As an illustration we present a new
Lie-algebraic method to compute frequency-space two-point functions for charged
scalar operators of CFT$_{1}$ dual to AdS$_{2}$ black hole with constant
background electric field. Our method is based on the real-time prescription of
AdS/CFT correspondence, Euclideanization of AdS$_{2}$ black hole and projective
unitary representations of the Lie algebra $\mathfrak{sl}(2,\mathbb{R}) \oplus
\mathfrak{sl}(2,\mathbb{R})$. We derive novel recurrence relations for
Euclidean CFT$_{1}$ two-point functions, which are exactly solvable and
completely determine the frequency- and charge-dependences of two-point
functions. Wick-rotating back to Lorentzian signature, we obtain retarded and
advanced CFT$_{1}$ two-point functions that are consistent with the known
results.


title:
The metallicity and dust content of a redshift 5 gamma-ray burst host
  galaxy

abstract:
  Observations of the afterglows of long gamma-ray bursts (GRBs) allow the
study of star-forming galaxies across most of cosmic history. Here we present
observations of GRB 111008A from which we can measure metallicity, chemical
abundance patterns, dust-to-metals ratio and extinction of the GRB host galaxy
at z=5.0. The host absorption system is a damped Lyman-alpha absorber (DLA)
with a very large neutral hydrogen column density of log N(HI)/cm^(-2) = 22.30
+/- 0.06, and a metallicity of [S/H]= -1.70 +/- 0.10. It is the highest
redshift GRB with such a precise metallicity measurement. The presence of
fine-structure lines confirms the z=5.0 system as the GRB host galaxy, and
makes this the highest redshift where Fe II fine-structure lines have been
detected. The afterglow is mildly reddened with A_V = 0.11 +/- 0.04 mag, and
the host galaxy has a dust-to-metals ratio which is consistent with being equal
to or lower than typical values in the Local Group.


title:
The dynamics of quantum criticality via Quantum Monte Carlo and
  holography

abstract:
  Understanding the real time dynamics of quantum systems without
quasiparticles constitutes an important yet challenging problem. We study the
superfluid-insulator quantum-critical point of bosons on a two-dimensional
lattice, a system whose excitations cannot be described in a quasiparticle
basis. We present detailed quantum Monte Carlo results for two separate lattice
realizations: their low-frequency conductivities are found to have the same
universal dependence on imaginary frequency and temperature. We then use the
structure of the real time dynamics of conformal field theories described by
the holographic gauge/gravity duality to make progress on the difficult problem
of analytically continuing the Monte Carlo data to real time. Our method yields
quantitative and experimentally testable results on the frequency-dependent
conductivity near the quantum critical point, and on the spectrum of
quasinormal modes in the vicinity of the superfluid-insulator quantum phase
transition. Extensions to other observables and universality classes are
discussed.

categories: cond-mat.str-el cond-mat.quant-gas gr-qc hep-th


title:
Galaxy mergers on a moving mesh: a comparison with smoothed-particle
  hydrodynamics

abstract:
  Galaxy mergers have been investigated for decades using smoothed particle
hydrodynamics (SPH), but recent work highlighting inaccuracies inherent in the
traditional SPH technique calls into question the reliability of previous
studies. We explore this issue by comparing a suite of Gadget-3 SPH simulations
of idealised (i.e., non-cosmological) isolated discs and galaxy mergers with
otherwise identical calculations performed using the moving-mesh code Arepo.
When black hole (BH) accretion and active galactic nucleus (AGN) feedback are
not included, the star formation histories (SFHs) obtained from the two codes
agree well. When BHs are included, the code- and resolution-dependent
variations in the SFHs are more significant, but the agreement is still good,
and the stellar mass formed over the course of a simulation is robust to
variations in the numerical method. During a merger, the gas morphology and
phase structure are initially similar prior to the starburst phase. However,
once a hot gaseous halo has formed from shock heating and AGN feedback (when
included), the agreement is less good. In particular, during the post-starburst
phase, the SPH simulations feature more prominent hot gaseous haloes and
spurious clumps, whereas with Arepo, gas clumps and filaments are less apparent
and the hot halo gas can cool more efficiently. We discuss the origin of these
differences and explain why the SPH technique yields trustworthy results for
some applications (such as the idealised isolated disc and galaxy merger
simulations presented here) but not others (e.g., gas flows onto galaxies in
cosmological hydrodynamical simulations).


title:
Cosmological dependence of the measurements of luminosity function,
  projected clustering and galaxy-galaxy lensing signal

abstract:
  Observables such as the luminosity function of galaxies, \Phi(M), the
projected clustering of galaxies, w_p(r_p), and the galaxy-galaxy lensing
signal, \Delta\Sigma, are often measured from galaxy redshift surveys assuming
a fiducial cosmological model for calculating distances to and between
galaxies. There is a growing number of studies that perform joint analyses of
these measurements and constrain cosmological parameters. We quantify the
amount by which such measurements systematically vary as the fiducial cosmology
used for the measurements is changed, and show that these effects can be
significant at high redshifts (z~0.5). We present a simple way that maps the
measurements made using a particular fiducial cosmological model to any other
cosmological model. Cosmological constraints (or halo occupation distribution
constraints) that use the luminosity function, clustering measurements and
galaxy-galaxy lensing signal but ignore these systematic effects may
underestimate the confidence intervals on the inferred parameters.


title:
The Nucleus of Comet 10P/Tempel 2 in 2013 and Consequences Regarding Its
  Rotational State: Early Science from the Discovery Channel Telescope

abstract:
  We present new lightcurve measurements of Comet 10P/Tempel 2 carried out with
Lowell Observatory's Discovery Channel Telescope in early 2013 when the comet
was at aphelion. These data represent some of the first science obtained with
this new 4.3-m facility. With Tempel 2 having been observed to exhibit a small
but ongoing spin-down in its rotation period for over two decades, our primary
goals at this time were two-fold. First, to determine its current rotation
period and compare it to that measured shortly after its most recent perihelion
passage in 2010, and second, to disentangle the spin-down from synodic effects
due to the solar day and the Earth's orbital motion and to determine the sense
of rotation, i.e. prograde or retrograde. At our midpoint of 2013 Feb 24, the
observed synodic period is 8.948+/-0.001 hr, exactly matching the predicted
prograde rotation solution based on 2010 results, and yields a sidereal period
of the identical value due to the solar and Earth synodic components just
canceling out during the interval of the 2013 observations. The retrograde
solution is ruled out because the associated sidereal periods in 2010 and 2013
are quite different even though we know that extremely little outgassing,
needed to produce torques, occurred in this interval. With a definitive sense
of rotation, the specific amounts of spin-down to the sidereal period could be
assessed. The nominal values imply that the rate of spin-down has decreased
over time, consistent with the secular drop in water production since 1988. Our
data also exhibited an unexpectedly small lightcurve amplitude which appears to
be associated with viewing from a large, negative sub-Earth latitude, and a
lightcurve shape deviating from a simple sinusoid implying a highly irregularly
shaped nucleus.


title: Polarity-driven surface metallicity in SmB$_6$

abstract:
  By a combined angle-resolved photoemission spectroscopy and density
functional theory study, we discover that the surface metallicity is
polarity-driven in SmB$_6$. Two surface states, not accounted for by the bulk
band structure, are reproduced by slab calculations for coexisting B$_6$ and Sm
surface terminations. Our analysis reveals that a metallic surface state stems
from an unusual property, generic to the (001) termination of all hexaborides:
the presence of boron $2p$ dangling bonds, on a polar surface. The discovery of
polarity-driven surface metallicity sheds new light on the 40-year old
conundrum of the low-temperature residual conductivity of SmB$_6$, and raises a
fundamental question in the field of topological Kondo insulators regarding the
interplay between polarity and nontrivial topological properties.


title:
The effect of metal enrichment and galactic winds on galaxy formation in
  cosmological zoom simulations

abstract:
  We investigate the differential effects of metal cooling and galactic stellar
winds on the cosmological formation of individual galaxies with three sets of
cosmological, hydrodynamical zoom simulations of 45 halos in the mass range
10^11<M_halo<10^13M_sun. Models including both galactic winds and metal cooling
(i) suppress early star formation at z>1 and predict reasonable star formation
histories, (ii) produce galaxies with high cold gas fractions (30-60 per cent)
at high redshift, (iii) significantly reduce the galaxy formation efficiencies
for halos (M_halo<10^12M_sun) at all redshifts in agreement with observational
and abundance matching constraints, (iv) result in high-redshift galaxies with
reduced circular velocities matching the observed Tully-Fisher relation at z~2,
and (v) significantly increase the sizes of low-mass galaxies
(M_stellar<3x10^10M_sun) at high redshift resulting in a weak size evolution -
a trend in agreement with observations. However, the low redshift (z<0.5) star
formation rates of massive galaxies are higher than observed (up to ten times).
No tested model predicts the observed size evolution for low-mass and high-mass
galaxies simultaneously. Due to the delayed onset of star formation in the wind
models, the metal enrichment of gas and stars is delayed and agrees well with
observational constraints. Metal cooling and stellar winds are both found to
increase the ratio of in situ formed to accreted stars - the relative
importance of dissipative vs. dissipationless assembly. For halo masses below
~10^12M_sun, this is mainly caused by less stellar accretion and compares well
to predictions from semi-analytical models but still differs from abundance
matching models. For higher masses, the fraction of in situ stars is
over-predicted due to the unrealistically high star formation rates at low
redshifts.


title: Galactic synchrotron emission with cosmic ray propagation models

abstract:
  Cosmic-ray (CR) leptons produce radio synchrotron radiation by gyrating in
interstellar magnetic fields (B-field). Details of B-fields, CR electron
distributions and propagation are still uncertain. We present developments in
our modelling of Galactic radio emission with the GALPROP code. It now includes
calculations of radio polarization, absorption, and free-free emission. Total
and polarized synchrotron emission are investigated in the context of physical
model of CR propagation. Predictions are compared with radio data from 22 MHz
to 2.3 GHz, and Wilkinson Microwave Anisotropy Probe data at 23 GHz. Spatial
and spectral effects on the synchrotron modelling with different CR
distribution, propagation halo size and CR propagation models are presented. We
find that all-sky total intensity and polarization maps are reasonably
reproduced by including an anisotropic B-field, with comparable intensity to
the regular one defined by rotation measures. A halo size of 10 kpc, which is
larger than usually assumed, is favoured. This work provides a basis for
further studies on foreground emission with the Planck satellite and on
interstellar gamma-ray emission with Fermi-Large Area Telescope.


title:
Discovery of Nine Intermediate Redshift Compact Quiescent Galaxies in
  the Sloan Digital Sky Survey

abstract:
  We identify nine galaxies with dynamical masses of M_dyn>10^10 M_sol as
photometric point sources, but with redshifts between z=0.2 and z=0.6, in the
Sloan Digital Sky Survey (SDSS) spectro-photometric database. All nine galaxies
have archival Hubble Space Telescope (HST) images. Surface brightness profile
fitting confirms that all nine galaxies are extremely compact (with
circularized half-light radii between 0.4 and 6.6 kpc and the median value of
0.74 kpc) for their velocity dispersion (110<sigma<340 km/s; median sigma=178
km/s). From the SDSS spectra, three systems are dominated by very young stars;
the other six are older than ~1 Gyr (two are E+A galaxies). The three young
galaxies have disturbed morphologies and the older systems have smooth profiles
consistent with a single Sersic function. All nine lie below the z~0 velocity
dispersion-half-light radius relation. The most massive system -
SDSSJ123657.44+631115.4 - lies right within the locus for massive compact z>1
galaxies and the other eight objects follow the high-redshift dynamical
size-mass relation.


title: All AdS_7 solutions of type II supergravity

abstract:
  In M-theory, the only AdS_7 supersymmetric solutions are AdS_7 x S^4 and its
orbifolds. In this paper, we find and classify new supersymmetric solutions of
the type AdS_7 x M_3 in type II supergravity. While in IIB none exist, in IIA
with Romans mass (which does not lift to M-theory) there are many new ones. We
use a pure spinor approach reminiscent of generalized complex geometry. Without
the need for any Ansatz, the system determines uniquely the form of the metric
and fluxes, up to solving a system of ODEs. Namely, the metric on M_3 is that
of an S^2 fibered over an interval; this is consistent with the Sp(1)
R-symmetry of the holographically dual (1,0) theory. By including D8 brane
sources, one can numerically obtain regular solutions, where topologically M_3
= S^3.


title: A new method to measure the mass of galaxy clusters

abstract:
  The mass measurement of galaxy clusters is an important tool for the
determination of cosmological parameters describing the matter and energy
content of the Universe. However, the standard methods rely on various
assumptions about the shape or the level of equilibrium of the cluster. We
present a novel method of measuring cluster masses. It is complementary to most
of the other methods, since it only uses kinematical information from outside
the virialized cluster. Our method identifies objects, as galaxy sheets or
filaments, in the cluster outer region, and infers the cluster mass by modeling
how the massive cluster perturbs the motion of the structures from the Hubble
flow. At the same time, this technique allows to constrain the
three-dimensional orientation of the detected structures with a good accuracy.
We use a cosmological numerical simulation to test the method. We then apply
the method to the Coma cluster, where we find two galaxy sheets, and measure
the mass of Coma to be Mvir=(9.2\pm2.4)10^{14} Msol, in good agreement with
previous measurements obtained with the standard methods.


title:
Magnetism in spin models for depleted honeycomb-lattice iridates:
  Spin-glass order towards percolation

abstract:
  Iridates are characterized by a fascinating interplay of spin-orbit and
electron-electron interactions. The honeycomb-lattice materials A2IrO3
(A=Na,Li) have been proposed to realize pseudospin-1/2 Mott insulating states
with strongly anisotropic exchange interactions, described by the
Heisenberg-Kitaev model, but other scenarios involving longer-range exchange
interactions or more delocalized electrons have been put forward as well. Here
we study the influence of non-magnetic doping, i.e., depleted moments, on the
magnetic properties of experimentally relevant variants of the
Heisenberg-Kitaev and Heisenberg J1-J2-J3 models. We generically find that the
zigzag order of the clean system is replaced, upon doping, by a spin-glass
state with short-ranged zigzag correlations. We determine the spin-glass
temperature as function of the doping level and argue that this quantity allows
to experimentally distinguish the different proposed spin models when the
doping is driven across the site percolation threshold of the honeycomb
lattice.


title: Natural Baryogenesis from Unnatural Supersymmetry

abstract:
  We demonstrate here that the mini-split version of the Minimal Supersymmetric
Standard Model (MSSM) including R-parity violating couplings naturally provides
all the necessary ingredients for a novel baryogenesis mechanism. The
baryogenesis is triggered by the late decay of a TeV scale bino after its
thermal freezeout. A \mu-term larger than the sfermion masses is necessary for
obtaining sufficient baryon asymmetry. Two example models of direct
baryogenesis and leptogenesis are proposed, with viable parameter spaces
presented. The cosmological conditions for the models--in particular, the
requirements of a long lifetime of bino and sufficient baryon asymmetry--point
towards the mini-split scale of $\sim$ 100-1000 TeV for the sfermion masses.
This provides an independent motivation for mini-split SUSY, along with the
constraints from flavor physics and Higgs mass measurement. We also discuss the
potential multi-pronged search for the signatures of such models, including
those at the Large Hadron Collider (LHC) and the low energy experiments at the
intensity frontier.


title: Revisiting toric SU(3) structures

abstract:
  Three-dimensional smooth compact toric varieties (SCTV) admit SU(3)
structures, and may thus be relevant for string compactifications, if they have
even first Chern class (c1). This condition can be fulfilled by infinitely many
SCTVs, including CP3 and CP1 bundles over all two-dimensional SCTVs. We show
that as long as c1 is even, toric SU(3) structures can be constructed using a
method proposed in arXiv:1005.2194. We perform a systematic study of the
parametric freedom of the resulting SU(3) structures, with a particular focus
on the metric and the torsion classes. Although metric positivity constrains
the SU(3) parameters, we find that every SCTV admits several toric SU(3)
structures and that parametric choices can sometimes be made to match
requirements of string vacua. We also provide a short review on the constraints
that an SU(3) structure must meet to be relevant for four-dimensional,
maximally symmetric N=1 or N=0 string vacua.


title: Characterizing unknown systematics in large scale structure surveys

abstract:
  Photometric large scale structure (LSS) surveys probe the largest volumes in
the Universe, but are inevitably limited by systematic uncertainties. Imperfect
photometric calibration leads to biases in our measurements of the density
fields of LSS tracers such as galaxies and quasars, and as a result in
cosmological parameter estimation. Earlier studies have proposed using
cross-correlations between different redshift slices or cross-correlations
between different surveys to reduce the effects of such systematics. In this
paper we develop a method to characterize unknown systematics. We demonstrate
that while we do not have sufficient information to correct for unknown
systematics in the data, we can obtain an estimate of their magnitude. We
define a parameter to estimate contamination from unknown systematics using
cross-correlations between different redshift slices and propose discarding
bins in the angular power spectrum that lie outside a certain contamination
tolerance level. We show that this method improves estimates of the bias using
simulated data and further apply it to photometric luminous red galaxies in the
Sloan Digital Sky Survey as a case study.


title: Random permutations of a regular lattice

abstract:
  Spatial random permutations were originally studied due to their connections
to Bose-Einstein condensation, but they possess many interesting properties of
their own. For random permutations of a regular lattice with periodic boundary
conditions, we prove existence of the infinite volume limit under fairly weak
assumptions. When the dimension of the lattice is two, we give numerical
evidence of a Kosterlitz-Thouless transition, and of long cycles having an
almost sure fractal dimension in the scaling limit. Finally we comment on
possible connections to Schramm-L\"owner curves.


title: A bosonic multi-state two-well model

abstract:
  Inspired by the increasing possibility of experimental control in ultracold
atomic physics, we introduce a new Lax operator and use it to construct and
solve models with two wells and two on-well states together with its
generalization for n on-well states. The models are solved by the algebraic
Bethe ansatz method and can be viewed as describing two Bose-Einstein
condensates allowing for an exchange interaction through Josephson tunnelling.

categories: quant-ph cond-mat.quant-gas hep-th math-ph math.MP nlin.SI


title: Strings on AdS Wormholes and Nonsingular Black Holes

abstract:
  Certain AdS black holes in the STU model can be conformally scaled to
wormhole and black hole solutions of an f(R) type theory which have two
asymptotically AdS regions and are completely free of curvature singularities.
While there is a delta-function source for the dilaton, classical string probes
are not sensitive to this singularity. If the AdS/CFT correspondence can be
applied in this context, then the wormhole background describes a phase in
which two copies of a conformal field theory interact with each other, whereas
the nonsingular black hole describes entangled states. By studying the behavior
of open strings on these backgrounds, we extract a number of features of the
quarks and anti-quarks that live in the field theories. In the interacting
phase, we find that there is a maximum speed with which the quarks can move
without losing energy, beyond which energy is transferred from a quark in one
field theory to a quark in the other. We also compute the rate at which moving
quarks within entangled states lose energy to the two surrounding plasmas.
While a quark-antiquark pair within a single field theory exhibits Coulomb
interaction for small separation, a quark in one field theory exhibits
spring-like confinement with an anti-quark in the other field theory. For the
entangled states, we study how the quark-antiquark screening length depends on
temperature and chemical potential. In the interacting phase of the two field
theories, a quadruplet made up of one quark-antiquark pair in each field theory
can undergo transitions involving how the quarks and antiquarks are paired in
terms of the screening.


title:
On the Crossing Number of Complete Graphs with an Uncrossed Hamiltonian
  Cycle

abstract:
  We prove new lower bounds on the crossing number of a complete graphs
assuming that it is drawn in such a way that it contains a Hamiltonian cycle
with no crossings.


title: Self-Organization In 1-d Swarm Dynamics

abstract:
  Self-organization of a biologically motivated swarm into smaller subgroups of
different velocities is found by solving a 1-dimensional adaptive-velocity
swarm, in which the velocity of an agent is averaged over a finite local radius
of influence. Using a mean field model in phase space, we find a dependence of
this group-division phenomenon on the typical scales of the initial swarm in
the position and velocity dimensions. Comparisons are made to previous swarm
models in which the speed of an agent is either fixed or adjusted according to
the degree of direction consensus among its local neighbors. Key words:
self-organization of swarm, phase space, multi-agent system, dynamical system,
group-division.


title: Dynamic Fisheye Grids for Binary Black Holes Simulations

abstract:
  We present a new warped gridding scheme adapted to simulating gas dynamics in
binary black hole spacetimes. The grid concentrates grid points in the vicinity
of each black hole to resolve the smaller scale structures there, and rarefies
grid points away from each black hole to keep the overall problem size at a
practical level. In this respect, our system can be thought of as a "double"
version of the fisheye coordinate system, used before in numerical relativity
codes for evolving binary black holes. The gridding scheme is constructed as a
mapping between a uniform coordinate system--in which the equations of motion
are solved--to the distorted system representing the spatial locations of our
grid points. Since we are motivated to eventually use this system for
circumbinary disc calculations, we demonstrate how the distorted system can be
constructed to asymptote to the typical spherical polar coordinate system,
amenable to efficiently simulating orbiting gas flows about central objects
with little numerical diffusion. We discuss its implementation in the Harm3d
code, tailored to evolve the magnetohydrodynamics equations in curved
spacetimes. We evaluate the performance of the system's implementation in
Harm3d with a series of tests, such as the advected magnetic field loop test,
magnetized Bondi accretion, and evolutions of hydrodynamic discs about a single
black hole and about a binary black hole. Like we have done with Harm3d, this
gridding scheme can be implemented in other unigrid codes as a (possibly)
simpler alternative to adaptive mesh refinement.


title: The McDonald Modified Weibull Distribution: Properties and Applications

abstract:
  A six parameter distribution so-called the McDonald modified Weibull
distribution is defined and studied. The new distribution contains, as special
submodels, several important distributions discussed in the literature, such as
the beta modified Weibull, Kumaraswamy modified Weibull, McDonald Weibull and
modified Weibull distribution,among others. The new distribution can be used
effectively in the analysis of survival data since it accommodates monotone,
unimodal and bathtub-shaped hazard functions. We derive the moments.We propose
the method of maximum likelihood for estimating the model parameters and obtain
the observed information matrix. A real data set is used to illustrate the
importance and flexibility of the new distribution.


title: Cumulants associated with geometric phases

abstract:
  The Berry phase can be obtained by taking the continuous limit of a cyclic
product $-\mbox{Im} \ln \prod_{I=0}^{M-1} \langle \Psi_0({\boldsymbol
  \xi}_I)|\Psi_0({\boldsymbol \xi}_{I+1})\rangle$, resulting in the circuit
integral $i \oint \mbox{d}{\boldsymbol \xi} \cdot \langle \Psi_0({\boldsymbol
  \xi})|\nabla_{\boldsymbol \xi}|\Psi_0({\boldsymbol \xi}\rangle$. Considering
a parametrized curve ${\boldsymbol \xi}(\chi)$ we show that the product
$\prod_{I=0}^{M-1} \langle \Psi_0(\chi_I)|\Psi_0( \chi_{I+1})\rangle$ can be
equated to a cumulant expansion. The first contributing term of this expansion
is the Berry phase itself, the other terms are the associated spread, skew,
kurtosis, etc. The cumulants are shown to be gauge invariant. It is also shown
that these quantities can be expressed in terms of an operator.


title: A Scalable Heuristic for Viral Marketing Under the Tipping Model

abstract:
  In a "tipping" model, each node in a social network, representing an
individual, adopts a property or behavior if a certain number of his incoming
neighbors currently exhibit the same. In viral marketing, a key problem is to
select an initial "seed" set from the network such that the entire network
adopts any behavior given to the seed. Here we introduce a method for quickly
finding seed sets that scales to very large networks. Our approach finds a set
of nodes that guarantees spreading to the entire network under the tipping
model. After experimentally evaluating 31 real-world networks, we found that
our approach often finds seed sets that are several orders of magnitude smaller
than the population size and outperform nodal centrality measures in most
cases. In addition, our approach scales well - on a Friendster social network
consisting of 5.6 million nodes and 28 million edges we found a seed set in
under 3.6 hours. Our experiments also indicate that our algorithm provides
small seed sets even if high-degree nodes are removed. Lastly, we find that
highly clustered local neighborhoods, together with dense network-wide
community structures, suppress a trend's ability to spread under the tipping
model.


title:
Casimir Force of Fermions Coupled to Monopoles in Six Dimensional
  Spacetime

abstract:
  We calculate the Casimir force for a fermionic quantum field in a piston
geometry with three parallel plates. The fermion satisfies bag boundary
conditions on the plates and the spacetime is assumed to have compact extra
dimensions. The calculation is performed in the cases where the extra space has
toroidal and spherical topology. We are mainly interested in the case in which
the fermion is coupled non-trivially to an extra dimensional defect, with a
torus extra dimensional topological background. We found that in certain
limits, the Casimir force corresponding to the defect-fermion system and to the
sphere, has opposite sign, in reference to those corresponding to the toroidal
extra dimensional spaces.


title: Nanomechanical AC Susceptometry of an Individual Mesoscopic Ferrimagnet

abstract:
  A novel method for simultaneous detection of both DC and time-dependent
magnetic signatures in individual mesoscopic structures has emerged from early
studies in spin mechanics. Multifrequency nanomechanical detection of AC
susceptibility and its harmonics highlights reversible nonlinearities in the
magnetization response of a single yttrium iron garnet (YIG) element,
separating them from hysteretic jumps in the DC magnetization.


title: Sustainable Software Ecosystems for Open Science

abstract:
  Sustainable software ecosystems are difficult to build, and require concerted
effort, community norms and collaborations. In science it is especially
important to establish communities in which faculty, staff, students and
open-source professionals work together and treat software as a first-class
product of scientific investigation-just as mathematics is treated in the
physical sciences. Kitware has a rich history of establishing collaborative
projects in the science, engineering and medical research fields, and continues
to work on improving that model as new technologies and approaches become
available. This approach closely follows and is enhanced by the movement
towards practicing open, reproducible research in the sciences where data,
source code, methodology and approach are all available so that complex
experiments can be independently reproduced and verified.


title: Contracting thin disks

abstract:
  We answer a question of Liokumovich-Nabutovsky-Rotman showing that if D is a
Riemannian 2-disc with boundary length L, diameter d and area A << d then D can
be filled by a homotopy where the lengths of the intermediate curves are
bounded by $L+2d+O(\sqrt A)$.


title:
Distillation of free entanglement from bound entangled states using weak
  measurements

abstract:
  We propose a scheme for distillation of free bipartite entanglement from
bipartite bound-entangled states. The crucial element of our scheme is an
ancillary system that is coupled to the initial bound-entangled state via
appropriate weak measurements. We show that in this protocol free entanglement
can be always generated with nonzero probability by using a single copy of the
bound-entangled state. We also derive a lower bound on the entanglement cost of
the protocol, and conclude that, on average, applying weaker measurements
results in relatively higher values of free entanglement as well as lower
costs.


title: Lift and wakes of flying snakes

abstract:
  Flying snakes use a unique method of aerial locomotion: they jump from tree
branches, flatten their bodies and undulate through the air to produce a glide.
The shape of their body cross-section during the glide plays an important role
in generating lift. This paper presents a computational investigation of the
aerodynamics of the cross-sectional shape. Two-dimensional simulations of
incompressible flow past the anatomically correct cross-section of the species
Chrysopelea paradisi show that a significant enhancement in lift appears at a
35-degrees angle of attack, above Reynolds numbers 2000. Previous experiments
on physical models also obtained an increased lift, at the same angle of
attack. The flow is inherently three-dimensional in physical experiments, due
to fluid instabilities, and it is thus intriguing that the enhanced lift also
appears in the two-dimensional simulations. The simulations point to the lift
enhancement arising from the early separation of the boundary layer on the
dorsal surface of the snake profile, without stall. The separated shear layer
rolls up and interacts with secondary vorticity in the near-wake, inducing the
primary vortex to remain closer to the body and thus cause enhanced suction,
resulting in higher lift.


title: Stability analysis of a model for the market dynamics of a smart grid

abstract:
  We consider the dynamics of a smart grid system characterized by widespread
distributed generation and storage devices. We assume that agents are free to
trade electric energy over the network and we focus on the emerging market
dynamics. We consider three different models for the market dynamics for which
we present a stability analysis. We see that stability depends on the specific
form of the market dynamics and it may depend on the structure of the
underlying network topology. We run numerical simulations that confirm our
theoretical predictions. As an example, we test our model for the market
dynamics over a real network topology, namely, the Tramway 11 Feeder from New
Mexico's power network.


title: The Three Loop Isotopy and Framed Isotopy Invariants of Virtual Knots

abstract:
  This paper introduces two virtual knot theory ``analogues'' of a well-known
family of invariants for knots in thickened surfaces: the Grishanov-Vassiliev
finite-type invariants of order two. The first, called the three loop isotopy
invariant, is an invariant of virtual knots while the second, called the three
loop framed isotopy invariant, is a regular isotopy invariant of framed virtual
knots. The properties of these invariants are investigated at length. In
addition, we make precise the informal notion of ``analogue''. Using this
formal definition, it is proved that a generalized three loop invariant is a
virtual knot theory analogue of a generalization of the Grishanov-Vassiliev
invariants of order two.


title: A maximum principle for hermitian (and other) metrics

abstract:
  We consider homomorphisms of hermitian holomorphic Hilbert bundles. Assuming
the homomorphism decreases curvature, we prove that its pointwise norm is
plurisubharmonic.


title:
Modifying the Electronic Orbitals of Nickelate Heterostructures Via
  Structural Distortions

abstract:
  We describe a general materials design approach that produces large orbital
energy splittings (orbital polarization) in nickelate heterostructures,
creating a two-dimensional single-band electronic surface at the Fermi energy.
The resulting electronic structure mimics that of the high temperature cuprate
superconductors. The two key ingredients are: (i) the construction of
atomic-scale distortions about the Ni site via charge transfer and internal
electric fields, and (ii) the use of three component (tri-component)
superlattices to break inversion symmetry. We use {\it ab initio} calculations
to implement the approach, with experimental verification of the critical
structural motif that enables the design to succeed.


title:
Chemistry of the Sagittarius Dwarf Galaxy: a Top-Light IMF, Outflows and
  the R-Process

abstract:
  From chemical abundance analysis of stars in the Sagittarius dwarf spheroidal
galaxy (Sgr), we conclude that the alpha-element deficiencies cannot be due to
the Type Ia supernova (SNIa) time-delay scenario of Tinsley (1979). Instead,
the evidence points to low [alpha/Fe] ratios resulting from an initial mass
function (IMF) deficient in the highest mass stars. The critical evidence is
the 0.4 dex deficiency of [O/Fe], [Mg/Fe] and other hydrostatic elements,
contrasting with the normal trend of r-process [Eu/Fe]r with [Fe/H]. Supporting
evidence comes from the hydrostatic element (O, Mg, Na, Al, Cu) [X/Fe] ratios,
which are inconsistent with iron added to the Milky Way (MW) disk trends. Also,
the ratio of hydrostatic to explosive (Si, Ca, Ti) element abundances suggests
a relatively top-light IMF. Abundance similarities with the LMC, Fornax and IC
1613, suggest that their alpha-element deficiencies also resulted from IMFs
lacking the most massive SNII.
  For such a top-light IMF, the normal trend of r-process [Eu/Fe]r with [Fe/H],
as seen in Sgr, indicates that massive Type II supernovae (>30Msun) cannot be
major sources of r-process elements.
  High [La/Y] ratios, consistent with leaky-box chemical evolution, are
confirmed but ~0.3 dex larger than theoretical AGB predictions. This may be due
to the 13C pocket mass, or a difference between MW and Sgr AGB stars. Sgr has
the lowest [Rb/Zr] ratios known, consistent with low-mass (~2Msun) AGB stars
near [Fe/H]=-0.6, likely resulting from leaky-box chemical evolution.
  The [Cu/O] trend in Sgr and the MW suggest that Cu yields increase with both
metallicity and stellar mass, as expected from Cu production by the weak
s-process in massive stars.
  Finally, we present an updated hfs line list, an abundance analysis of
Arcturus, and further develop our error analysis formalism.


title:
These are not the k-mers you are looking for: efficient online k-mer
  counting using a probabilistic data structure

abstract:
  K-mer abundance analysis is widely used for many purposes in nucleotide
sequence analysis, including data preprocessing for de novo assembly, repeat
detection, and sequencing coverage estimation. We present the khmer software
package for fast and memory efficient online counting of k-mers in sequencing
data sets. Unlike previous methods based on data structures such as hash
tables, suffix arrays, and trie structures, khmer relies entirely on a simple
probabilistic data structure, a Count-Min Sketch. The Count-Min Sketch permits
online updating and retrieval of k-mer counts in memory which is necessary to
support online k-mer analysis algorithms. On sparse data sets this data
structure is considerably more memory efficient than any exact data structure.
In exchange, the use of a Count-Min Sketch introduces a systematic overcount
for k-mers; moreover, only the counts, and not the k-mers, are stored. Here we
analyze the speed, the memory usage, and the miscount rate of khmer for
generating k-mer frequency distributions and retrieving k-mer counts for
individual k-mers. We also compare the performance of khmer to several other
k-mer counting packages, including Tallymer, Jellyfish, BFCounter, DSK, KMC,
Turtle and KAnalyze. Finally, we examine the effectiveness of profiling
sequencing error, k-mer abundance trimming, and digital normalization of reads
in the context of high khmer false positive rates. khmer is implemented in C++
wrapped in a Python interface, offers a tested and robust API, and is freely
available under the BSD license at github.com/ged-lab/khmer.


title:
Dynamical control of orbital occupations via a ferroelectric-induced
  polar state in metallic manganites

abstract:
  The breaking of orbital degeneracy on a transition metal cation and the
resulting unequal electronic occupations of these orbitals provide a powerful
lever over electron density and spin ordering in metal oxides. Here, we show
how to dynamically modulate the orbital populations on Mn atoms at
ferroelectric/manganite interfaces by switching the ferroelectric polarization.
The change in orbital occupation can be as large as 10\%, greatly exceeding
that of bulk manganites. This flippable orbital splitting is in large part
controlled by the propagation of ferroelectric polar displacements into the
interfacial region, a structural motif absent in the bulk and unique to the
interface. We use {\it ab initio} theory, epitaxial thin film growth, and
scanning transmission electron microscopy to verify the predicted interfacial
polar state and concomitant orbital splittings.


title: The Spacetime of Double Field Theory: Review, Remarks, and Outlook

abstract:
  We review double field theory (DFT) with emphasis on the doubled spacetime
and its generalized coordinate transformations, which unify diffeomorphisms and
b-field gauge transformations. We illustrate how the composition of generalized
coordinate transformations fails to associate. Moreover, in dimensional
reduction, the O(d,d) T-duality transformations of fields can be obtained as
generalized diffeomorphisms. Restricted to a half-dimensional subspace, DFT
includes `generalized geometry', but is more general in that local patches of
the doubled space may be glued together with generalized coordinate
transformations. Indeed, we show that for certain T-fold backgrounds with
non-geometric fluxes, there are generalized coordinate transformations that
induce, as gauge symmetries of DFT, the requisite O(d,d;Z) monodromy
transformations. Finally we review recent results on the \alpha' extension of
DFT which, reduced to the half-dimensional subspace, yields intriguing
modifications of the basic structures of generalized geometry.


title:
Maximizing the Power of Principal Components Analysis of Correlated
  Phenotypes in Genome-wide Association Studies

abstract:
  Principal Component analysis (PCA) is a useful statistical technique that is
commonly used for multivariate analysis of correlated variables. It is usually
applied as a dimension reduction method: the top principal components (PCs)
explaining most of total variance are tested for association with a predictor
of interest, and the remaining PCs are ignored. This strategy has been widely
applied in genetic epidemiology, however some of its aspects are not well
appreciated in the context of single nucleotide polymorphisms (SNPs)
association testing. In this study, we review the theoretical basis of PCA and
its behavior when testing for association between a SNP and two correlated
traits under various scenarios. We then evaluate with simulations the power of
several different PCA-based strategies when analyzing up to 100 correlated
traits. We show that contrary to widespread practice that testing the top PCs
only can be dramatically underpowered since PCs explaining a low amount of the
total phenotypic variance can harbor substantial genetic associations.
Furthermore, we demonstrate that PC-based strategies that use all PCs have
great potential to detect negatively pleiotropic genetic variants (e.g.
variants with opposite effects on positively correlated traits) and genetic
variants that are exclusively associated with a single trait, but only achieve
a moderate gain in power to detect positive pleiotropic genetic loci. Finally,
the genome-wide association study of five correlated coagulation traits in 685
subjects from the MARTHA study confirms these results. The joint analysis of
the five PCs from the coagulation traits identified two new candidate SNPs,
which were most strongly associated with the 5th PC that explained the smallest
amount of phenotypic variance.


title: Fitness Probability Distribution of Bit-Flip Mutation

abstract:
  Bit-flip mutation is a common mutation operator for evolutionary algorithms
applied to optimize functions over binary strings. In this paper, we develop
results from the theory of landscapes and Krawtchouk polynomials to exactly
compute the probability distribution of fitness values of a binary string
undergoing uniform bit-flip mutation. We prove that this probability
distribution can be expressed as a polynomial in p, the probability of flipping
each bit. We analyze these polynomials and provide closed-form expressions for
an easy linear problem (Onemax), and an NP-hard problem, MAX-SAT. We also
discuss some implications of the results for runtime analysis.


title:
High Fidelity Detection of the Orbital Angular Momentum of Light by Time
  Mapping

abstract:
  We demonstrate high-fidelity detection of the orbital angular momentum (OAM)
of light using a compact and practical OAM spectrometer that maps the OAM
spectrum to time. The spectrometer consists of a single optical delay loop to
achieve timing mapping, a vortex phase plate that iteratively decreases the OAM
value, and a single mode fibre to distinguish zero from non-zero OAM states.
Light with arbitrarily OAM compositions can be measured. For light with OAM up
to 4hbar, we measured an average crosstalk of -21.3 dB, which is mainly limited
by the purity of the input states and optical alignment.


title:
A Non-Phylogenetic Conceptual Network Architecture for Organizing
  Classes of Material Artifacts into Cultural Lineages

abstract:
  The application of phylogenetic techniques to the documentation of cultural
history can present a distorted picture due to horizontal transmission and
blending. Moreover, the units of cultural transmission must be communicable
concepts, rather than conveniently measurable attributes, and relatedness
between elements of culture often resides at the conceptual level, something
not captured by phylogenetic methods, which focus on measurable attributes.
(For example, mortars and pestles are as related as two artifacts could be,
despite little similarity at the attribute level.) This paper introduces a new,
cognitively inspired framework for chronicling material cultural history,
building on Lipo's (2005) network-based computational approach. We show that by
incorporating not just superficial attributes of artifact samples (e.g.
fluting) but also conceptual knowledge (e.g. information about function), a
different pattern of cultural ancestry emerges.


title: On hedging American options under model uncertainty

abstract:
  We consider as given a discrete time financial market with a risky asset and
options written on that asset and determine both the sub- and super-hedging
prices of an American option in the model independent framework of
ArXiv:1305.6008. We obtain the duality of results for the sub- and
super-hedging prices. For the sub-hedging prices we discuss whether the sup and
inf in the dual representation can be exchanged (a counter example shows that
this is not true in general). For the super-hedging prices we discuss several
alternative definitions and argue why our choice is more reasonable. Then
assuming that the path space is compact, we construct a discretization of the
path space and demonstrate the convergence of the hedging prices at the optimal
rate. The latter result would be useful for numerical computation of the
hedging prices. Our results generalize those of ArXiv:1304.3574 to the case
when static positions in (finitely many) European options can be used in the
hedging portfolio.


title: Langevin diffusions and the Metropolis-adjusted Langevin algorithm

abstract:
  We provide a clarification of the description of Langevin diffusions on
Riemannian manifolds and of the measure underlying the invariant density. As a
result we propose a new position-dependent Metropolis-adjusted Langevin
algorithm (MALA) based upon a Langevin diffusion in $\mathbb{R}^d$ which has
the required invariant density with respect to Lebesgue measure. We show that
our diffusion and the diffusion upon which a previously-proposed
position-dependent MALA is based are equivalent in some cases but are distinct
in general. A simulation study illustrates the gain in efficiency provided by
the new position-dependent MALA.


title:
How conventional measures overestimate electroweak fine-tuning in
  supersymmetric theory

abstract:
  The lack of evidence for superparticles at the CERN LHC, along with the
rather high value of the Higgs mass, has sharpened the perception that
supersymmetric model parameter space is highly electroweak fine-tuned (EWFT).
We compare three measures of fine-tuning in SUSY models. 1. \Del_HS measures a
terms containing large log contributions to m_Z that are inevitable in models
defined at scales much higher than the electroweak scale. 2. \Del_BG measures
variation in m_Z against variation of model parameters and allows for
correlations among high scale parameters which are not included in \Del_HS. 3.
The model-independent \Del_EW measures how naturally a model can generate the
measured value of m_Z=91.2 GeV in terms of weak scale parameters alone. We
hypothesize an overarching Ultimate Theory (UTH) wherein the high scale soft
terms are all correlated. The UTH might be contained within the more general
effective SUSY theories popular in the literature. For \Del_HS, EWFT can be
overestimated by neglecting additional non-independent terms which lead to
large cancellations. For \Del_BG, EWFT can be overestimated by applying the
measure to the effective theories instead of to the UTH. The measure \Del_EW
allows for the possibility of parameter correlations which should be present in
the UTH and, since it is model-independent, provides the same value of EWFT for
the effective theories as should occur for the UTH. We find that the well-known
mSUGRA/CMSSM model is fine-tuned under all three measures so that it is
unlikely to contain the UTH. The non-universal Higgs model NUHM2 appears
fine-tuned with \Del_HS,BG > 10^3. But since \Del_EW can be as small as 7
(corresponding to 14% fine-tuning), it may contain the UTH for parameter ranges
which allow for low true EWFT.


title:
Dynamical Disequilibrium, Transformation, and the Evolution and
  Development of Sustainable Worldviews

abstract:
  This chapter begins by outlining a promising, new theoretical framework for
the process by which human culture evolves inspired by the views of complexity
theorists on the problem of how life began. Elements of culture, like species,
evolve over time; that is, they exhibit cumulative change that is adaptive in
nature. By studying how biological evolution got started, we gain insight into
not just the specifics of biological evolution, but also general insights into
the initiation of any evolutionary process that may be applicable to culture.
We then explore the implications of this new framework for culture on the
transformative processes of individuals. Specifically, we will address what
this emerging perspective on cultural evolution implies for to go about
attaining a sustainable worldview; that is, a web of habits, understandings,
and ways of approaching situations that is conducive to the development of a
sustainable world.


title: Two-Component Dark Matter

abstract:
  We study an extension of the Standard Model (SM) with two interacting cold
Dark Matter (DM) candidates: a neutral Majorana fermion ($\nu$) and a neutral
scalar singlet ($\varphi$). The scalar $\varphi$ interacts with the SM through
the "Higgs portal" coupling while $\nu$ at the tree level interacts only with
$\varphi$ through Yukawa interactions. The relic abundance of $\nu$ and
$\varphi$ is found by solving the Boltzmann equations numerically; for the case
$m_\nu > m_\varphi$ we also derive a reliable approximate analytical solution.
Effects of the interaction between the two DM components are discussed. A scan
over the parameter space is performed to determine the regions consistent with
the WMAP data for DM relic abundance, and with the XENON100 direct detection
limits for the DM-nucleus cross section. We find that although a large region
of the parameter space is allowed by the WMAP constraints, the XENON100 data
severely restricts the parameter space. Taking into account only amplitudes
generated at the tree level one finds three allowed regions for the scalar
mass: $m_\varphi \sim 62.5$ GeV (corresponding to the vicinity of the Higgs
boson resonance responsible for $\varphi\varphi$ annihilation into SM
particles), $m_\varphi \simeq 130-140$ GeV and $m_\varphi \gesim 3 $TeV. 1-loop
induced $\nu$-nucleon scattering has been also calculated and discussed. A
possibility of DM direct detection by the CREST-II experiment was considered.


title: The Average Sensitivity of an Intersection of Half Spaces

abstract:
  We prove new bounds on the average sensitivity of the indicator function of
an intersection of $k$ halfspaces. In particular, we prove the optimal bound of
$O(\sqrt{n\log(k)})$. This generalizes a result of Nazarov, who proved the
analogous result in the Gaussian case, and improves upon a result of Harsha,
Klivans and Meka. Furthermore, our result has implications for the runtime
required to learn intersections of halfspaces.


title:
Feasibility of the Spin-Light Polarimetry Technique for Longitudinally
  Polarized Electron Beams

abstract:
  A novel polarimeter based on the asymmetry in the spacial distribution of
synchrotron radiation will make for a fine addition to the existing M{\o}ller
and Compton polarimeters. The spin light polarimeter consists of a set of
wiggler magnet along the beam that generate synchrotron radiation. The spacial
distribution of synchrotron radiation will be measured by ionization chambers.
The up-down (below and above the wiggle) spacial asymmetry in the transverse
plain is used to quantify the polarization of the beam. As a part of the design
process, effects of a realistic wiggler magnetic field and an extended beam
size were studied. The perturbation introduced by these effects was found to be
negligible. Lastly, a full fledged GEANT-4 simulation was built to study the
response of the ionization chamber.


title: Phase behavior of binary mixtures of hard convex polyehdra

abstract:
  Shape anisotropy of colloidal nanoparticles has emerged as an important
design variable for engineering assemblies with targeted structure and
properties. In particular, a number of polyhedral nanoparticles have been shown
to exhibit a rich phase behavior [Agarwal et al., Nature Materials, 2011, 10,
230]. Since real synthesized particles have polydispersity not only in size but
also in shape, we explore here the phase behavior of binary mixtures of hard
convex polyhedra having similar sizes but different shapes. Choosing
representative particle shapes from those readily synthesizable, we study in
particular four mixtures: (i) cubes and spheres (with spheres providing a
non-polyhedral reference case), (ii) cubes and truncated octahedra, (iii) cubes
and cuboctahedra, and (iv) cuboctahedra and truncated octahedra. The phase
behavior of such mixtures is dependent on the interplay of mixing and packing
entropy, which can give rise to miscible or phase-separated states. The extent
of mixing of two such particle types is expected to depend on the degree of
shape similarity, relative sizes, composition, and compatibility of the crystal
structures formed by the pure components. While expectedly the binary systems
studied exhibit phase separation at high pressures due to the incompatible
pure-component crystal structures, our study shows that the essential
qualitative trends in miscibility and phase separation can be correlated to
properties of the pure components, such as the relative values of the
order-disorder transition pressure (ODP) of each component. Specifically, if
for a mixture A+B we have that ODP_B <ODP_A and \Delta ODP = ODP_A - ODP_B,
then at any particular pressure where phase separation occurs, the larger the
\Delta ODP the lower the solubility of A in the B-rich ordered phase and the
higher the solubility of B in the A-rich ordered phase.

categories: cond-mat.soft cond-mat.mtrl-sci cond-mat.stat-mech physics.chem-ph


title:
Sea quark transverse momentum distributions and dynamical chiral
  symmetry breaking

abstract:
  Recent theoretical studies have provided new insight into the intrinsic
transverse momentum distributions of valence and sea quarks in the nucleon at a
low scale. The valence quark transverse momentum distributions (q - qbar) are
governed by the nucleon's inverse hadronic size R^{-1} ~ 0.2 GeV and drop
steeply at large p_T. The sea quark distributions (qbar) are in large part
generated by non-perturbative chiral-symmetry-breaking interactions and extend
up to the scale rho^{-1} ~ 0.6 GeV. These findings have many implications for
modeling the initial conditions of perturbative QCD evolution of TMD
distributions (starting scale, shape of p_T distributions, coordinate-space
correlation functions). The qualitative difference between valence and sea
quark intrinsic p_T distributions could be observed experimentally, by
comparing the transverse momentum distributions of selected hadrons in
semi-inclusive deep-inelastic scattering, or those of dileptons produced in pp
and pbar-p scattering.


title:
Precision near-infrared radial velocity instrumentation II: Non-Circular
  Core Fiber Scrambler

abstract:
  We have built and commissioned a prototype agitated non-circular core fiber
scrambler for precision spectroscopic radial velocity measurements in the
near-infrared H band. We have collected the first on-sky performance and modal
noise tests of these novel fibers in the near-infrared at H and K bands using
the CSHELL spectrograph at the NASA InfraRed Telescope Facility (IRTF). We
discuss the design behind our novel reverse injection of a red laser for
co-alignment of star-light with the fiber tip via a corner cube and visible
camera. We summarize the practical details involved in the construction of the
fiber scrambler, and the mechanical agitation of the fiber at the telescope. We
present radial velocity measurements of a bright standard star taken with and
without the fiber scrambler to quantify the relative improvement in the
obtainable blaze function stability, the line spread function stability, and
the resulting radial velocity precision. We assess the feasibility of applying
this illumination stabilization technique to the next generation of
near-infrared spectrographs such as iSHELL on IRTF and an upgraded NIRSPEC at
Keck. Our results may also be applied in the visible for smaller core diameter
fibers where fiber modal noise is a significant factor, such as behind an
adaptive optics system or on a small < 1 meter class telescope such as is being
pursued by the MINERVA and LCOGT collaborations.


title:
Precision near-infrared radial velocity instrumentation I: Absorption
  Gas Cells

abstract:
  We have built and commissioned gas absorption cells for precision
spectroscopic radial velocity measurements in the near-infrared in the H and K
bands. We describe the construction and installation of three such cells filled
with 13CH4, 12CH3D, and 14NH3 for the CSHELL spectrograph at the NASA Infrared
Telescope Facility (IRTF). We have obtained their high-resolution laboratory
Fourier Transform spectra, which can have other practical uses. We summarize
the practical details involved in the construction of the three cells, and the
thermal and mechanical control. In all cases, the construction of the cells is
very affordable. We are carrying out a pilot survey with the 13CH4 methane gas
cell on the CSHELL spectrograph at the IRTF to detect exoplanets around low
mass and young stars. We discuss the current status of our survey, with the aim
of photon-noise limited radial velocity precision. For adequately bright
targets, we are able to probe a noise floor of 7 m/s with the gas cell with
CSHELL at cassegrain focus. Our results demonstrate the feasibility of using a
gas cell on the next generation of near-infrared spectrographs such as iSHELL
on IRTF, iGRINS, and an upgraded NIRSPEC at Keck.


title:
Solute transport predicts scaling of surface reaction rates in porous
  media: Applications to silicate weathering

abstract:
  We apply our theory of conservative solute transport, based on concepts from
percolation theory, directly and without modification to reactive solute
transport. This theory has previously been shown to predict the observed range
of dispersivity values for conservative solute transport over ten orders of
magnitude of length scale. We now show that the temporal dependence derived for
the solute velocity accurately predicts the time-dependence for the weathering
of silicate minerals over nine orders of magnitude of time scale, while its
predicted length dependence agrees with data obtained for reaction rates over
five orders of magnitude of length scale. In both cases, it is possible to
unify lab and field results. Thus, net reaction rates appear to be limited by
solute transport velocities. We suggest the possible relevance of our results
to landscape evolution of the earth's terrestrial surface.


title: Percolation with long-range correlated disorder

abstract:
  Long-range power-law correlated percolation is investigated using Monte Carlo
simulations. We obtain several static and dynamic critical exponents as
function of the Hurst exponent $H$ which characterizes the degree of spatial
correlation among the occupation of sites. In particular, we study the fractal
dimension of the largest cluster and the scaling behavior of the second moment
of the cluster size distribution, as well as the complete and accessible
perimeters of the largest cluster. Concerning the inner structure and transport
properties of the largest cluster, we analyze its shortest path, backbone, red
sites, and conductivity. Finally, bridge site growth is also considered. We
propose expressions for the functional dependence of the critical exponents on
$H$.


title:
Covalency and the metal-insulator transition in titanate and vanadate
  perovskites

abstract:
  A combination of density functional and dynamical mean-field theory is
applied to the perovskites SrVO$_3$, LaTiO$_3$ and LaVO$_3$. We show that
DFT+DMFT in conjunction with the standard fully localized-limit (FLL)
double-counting predicts that LaTiO$_3$ and LaVO$_3$ are metals even though
experimentally they are correlation-driven ("Mott") insulators. In addition,
the FLL double counting implies a splitting between oxygen $p$ and transition
metal $d$ levels which differs from experiment. Introducing into the theory an
\textit{ad hoc} double counting correction which reproduces the experimentally
measured insulating gap leads also to a $p$-$d$ splitting consistent with
experiment if the on-site interaction $U$ is chosen in a relatively narrow
range ($\sim 6\pm 1$ eV). The results indicate that these early transition
metal oxides will serve as critical test for the formulation of a general
\textit{ab initio} theory of correlated electron metals.


title: Origin of the tail in Green's functions in odd dimensional space-times

abstract:
  It is well known that the scalar field Green's function in odd dimensions has
a tail, i.e. a non-zero support inside the light cone, which in turn implies
that the Huygens' principle is violated. However, the reason behind this
behavior is still not quite clear. In this paper we shed more light on the
physical origin of the tail by regularizing the term which is usually ignored
in the literature since it vanishes due to the action of the delta function.
With this extra term the Green's function does not satisfy the source-free wave
equation (in the region outside of the source). We show that this term
corresponds to a charge imprinted on the light cone shell. Unlike the vector
field charge, a moving scalar field charge is not Lorentz invariant and is
contracted by the relativistic $\sqrt{1-v^2}$ factor. If a scalar charge is
moving at the speed of light, it appears to be zero in the static (with respect
to the original physical charge) observer's frame. However, the field it
sources is not entirely on the light cone. Thus, it is likely that this hidden
charge sources the mysterious tail in odd dimensions.


title: On Hall-Littlewood polynomials

abstract: An observation on Hall-Littlewood polynomials.


title: Relative Bogomolov extensions

abstract:
  An algebraic extension K of the rationals has the Bogomolov property if the
absolute logarithmic height of non-torsion points of K* is bounded away from 0.
We define a relative extension L/K to be Bogomolov if this holds for points of
L\K. We construct various examples of extensions which are and are not
Bogomolov. We prove a ramification criterion for this property, and use it to
show that such extensions can always be constructed if some rational prime has
bounded ramification index in K, when K is Galois over Q.


title:
Infrared Spectroscopic Survey of the Quiescent Medium of Nearby Clouds:
  I. Ice Formation and Grain Growth in Lupus

abstract:
  Infrared photometry and spectroscopy (1-25 um) of background stars reddened
by the Lupus molecular cloud complex are used to determine the properties of
the grains and the composition of the ices before they are incorporated into
circumstellar envelopes and disks. H2O ices form at extinctions of
Ak=0.25+/-0.07 mag (Av=2.1+/-0.6). Such a low ice formation threshold is
consistent with the absence of nearby hot stars. Overall, the Lupus clouds are
in an early chemical phase. The abundance of H2O ice (2.3+/-0.1*10^-5 relative
to Nh) is typical for quiescent regions, but lower by a factor of 3-4 compared
to dense envelopes of YSOs. The low solid CH3OH abundance (<3-8% relative to
H2O) indicates a low gas phase H/CO ratio, which is consistent with the
observed incomplete CO freeze out. Furthermore it is found that the grains in
Lupus experienced growth by coagulation. The mid-infrared (>5 um) continuum
extinction relative to Ak increases as a function of Ak. Most Lupus lines of
sight are well fitted with empirically derived extinction curves corresponding
to Rv~ 3.5 (Ak=0.71) and Rv~5.0 (Ak=1.47). For lines of sight with Ak>1.0 mag,
the tau9.7/Ak ratio is a factor of 2 lower compared to the diffuse medium.
Below 1.0 mag, values scatter between the dense and diffuse medium ratios. The
absence of a gradual transition between diffuse and dense medium-type dust
indicates that local conditions matter in the process that sets the tau9.7/Ak
ratio. This process is likely related to grain growth by coagulation, as traced
by the A7.4/Ak continuum extinction ratio, but not to ice mantle formation.
Conversely, grains acquire ice mantles before the process of coagulation
starts.


title:
Trust--Region Problems with Linear Inequality Constraints: Exact SDP
  Relaxation, Global Optimality and Robust Optimization

abstract:
  The trust-region problem, which minimizes a nonconvex quadratic function over
a ball, is a key subproblem in trust-region methods for solving nonlinear
optimization problems. It enjoys many attractive properties such as an exact
semi-definite linear programming relaxation (SDP relaxation) and strong
duality. Unfortunately, such properties do not, in general, hold for an
extended trust-region problem having extra linear constraints. This paper shows
that two useful and powerful features of the classical trust-region problem
continue to hold for an extended trust-region problem with linear inequality
constraints under a new dimension condition. First, we establish that the class
of extended trust-region problems has an exact SDP-relaxation, which holds
without the Slater constraint qualification. This is achieved by proving that a
system of quadratic and affine functions involved in the model satisfies a
range-convexity whenever the dimension condition is fulfilled. Second, we show
that the dimension condition together with the Slater condition ensures that a
set of combined first and second-order Lagrange multiplier conditions is
necessary and sufficient for global optimality of the extended trust-region
problem and consequently for strong duality. Finally, we show that the
dimension condition is easily satisfied for the extended trust-region model
that arises from the reformulation of a robust least squares problem (LSP) as
well as a robust second order cone programming model problem (SOCP) as an
equivalent semi-definite linear programming problem. This leads us to conclude
that, under mild assumptions, solving a robust (LSP) or (SOCP) under
matrix-norm uncertainty or polyhedral uncertainty is equivalent to solving a
SDP and so, their solutions can be validated in polynomial time.


title: The Orbit Space and Basic Forms of a Proper Lie Groupoid

abstract:
  A classical result in differential geometry states that for a free and proper
Lie group action, the quotient map to the orbit space induces an isomorphism
between the de Rham complex of differential forms on the orbit space and the
basic differential forms on the original manifold. In this paper, this result
is generalized to the case of a proper Lie groupoid, in which the orbit space
is equipped with the quotient diffeological structure. As an application of
this, we obtain a de Rham theorem for the de Rham complex on the orbit space.


title:
The Late-Pleistocene extinction of megafauna compared with the growth of
  human population

abstract:
  Time-dependent distribution of the global extinction of megafauna is compared
with the growth of human population. There is no correlation between the two
processes. Furthermore, the size of human population and its growth rate were
far too small to have any significant impact on the environment and on the life
of megafauna.


title: Charmonia and Bottomonia in a Magnetic Field

abstract:
  We study the effect of a static homogeneous external magnetic field on
charmonium and bottomonium states. In an external magnetic field, quarkonium
states do not have a conserved center-of-mass momentum. Instead there is a new
conserved quantity called the pseudomomentum which takes into account the
Lorentz force on the particles in the system. When written in terms of the
pseudomomentum, the internal and center-of-mass motions do not decouple and, as
a result, the properties of quarkonia depend on the states' center-of-mass
momentum. We analyze the behavior of heavy particle-antiparticle pairs subject
to an external magnetic field assuming a three dimensional harmonic potential
and Cornell potential plus spin-spin interaction. In the case of the Cornell
potential, we also take into account the mixing of the eta_c and J/psi states
and eta_b and Upsilon states due to the background magnetic field. We then
numerically calculate the dependence of the masses and mixing fractions on the
magnitude of the background magnetic field and center-of-mass momentum of the
state.


title: Intensity interferometry for observation of dark objects

abstract:
  We analyze an intensity interferometry measurement carried out with two
point-like detectors facing a distant source (e.g., a star) that may be
partially occluded by an absorptive object (e.g., a planet). Such a
measurement, based on the perturbation of the observed covariance function due
to the object's presence, can provide information of the object complementary
to a direct optical intensity measurement. In particular, one can infer the
orientation of the object's transient trajectory. We identify the key
parameters that impact this perturbation and show that its magnitude is equal
to the magnitude of the intensity variation caused by the same object. In
astronomy applications, this value may be very small, so a differential
measurement may be necessary. Finally, we discuss the signal-to-noise ratio
that may be expected in this type of measurement.


title:
Crossover of Magnetoresistance from Fourfold to Twofold Symmetry in SmB6
  Single Crystal, a topological Kondo insulator

abstract:
  Topological Kondo insulators have been attracting great attention from the
condensed-matter physics community due to their fascinating topological and
strongly correlated properties. Here, we report angle-dependent c-axis
magnetoresistance (MR) oscillations in a Kondo insulator, SmB6 single crystal,
in a magnetic field of up to 13 T rotated in the ab-plane. Four-fold symmetric
MR oscillations are first observed above 8 K, which result from the four-fold
(C4) degeneracy of the bulk Fermi surface of SmB6. With decreasing temperature
down to 2.3 K, the C4 symmetry of the MR oscillations gradually weakens and C2
symmetry appears. This demonstrates a crossover from three-dimensional bulk
states to two-dimensional surface states and implies the possible emergence of
topological nematic states. Our experimental observations shed new light on the
metallic surface states and nematic states in the Kondo insulator SmB6.


title:
The Classification Accuracy of Multiple-Metric Learning Algorithm on
  Multi-Sensor Fusion

abstract:
  This paper focuses on two main issues; first one is the impact of Similarity
Search to learning the training sample in metric space, and searching based on
supervised learning classi-fication. In particular, four metrics space
searching are based on spatial information that are introduced as the
following; Cheby-shev Distance (CD); Bray Curtis Distance (BCD); Manhattan
Distance (MD) and Euclidean Distance(ED) classifiers. The second issue
investigates the performance of combination of mul-ti-sensor images on the
supervised learning classification accura-cy. QuickBird multispectral data (MS)
and panchromatic data (PAN) have been used in this study to demonstrate the
enhance-ment and accuracy assessment of fused image over the original images.
The supervised classification results of fusion image generated better than the
MS did. QuickBird and the best results with ED classifier than the other did.


title: On the Relationship Between Dual Photography and Classical Ghost Imaging

abstract:
  Classical ghost imaging has received considerable attention in recent years
because of its remarkable ability to image a scene without direct observation
by a light-detecting imaging device. In this article, we show that this imaging
process is actually a realization of a paradigm known as dual photography,
which has been shown to produce full-color dual (ghost) images of 3D objects
with complex materials without using a traditional imaging device.
Specifically, we demonstrate mathematically that the cross-correlation based
methods used to recover ghost images are equivalent to the light transport
measurement process of dual photography. Because of this, we are able to
provide a new explanation for ghost imaging using only classical optics by
leveraging the principle of reciprocity in classical electromagnetics. This
observation also shows how to leverage previous work on light transport
acquisition and dual photography to improve ghost imaging systems in the
future.


title: A New Electric Field in Asymmetric Magnetic Reconnection

abstract:
  We present a theory and numerical evidence for the existence of a previously
unexplored in-plane electric field in collisionless asymmetric magnetic
reconnection. This electric field, dubbed the "Larmor electric field," is
associated with finite Larmor radius effects and is distinct from the known
Hall electric field. Potentially, it could be an important indicator for the
upcoming Magnetospheric Multiscale (MMS) mission to locate reconnection sites
as we expect it to appear on the magnetospheric side, pointing Earthward, at
the dayside magnetopause reconnection site.


title:
The UV-bright, Slowly Declining Transient PS1-11af as a Partial Tidal
  Disruption Event

abstract:
  We present the Pan-STARRS1 discovery of the long-lived and blue transient
PS1-11af, which was also detected by GALEX with coordinated observations in the
near-ultraviolet (NUV) band. PS1-11af is associated with the nucleus of an
early-type galaxy at redshift z=0.4046 that exhibits no evidence for star
formation or AGN activity. Four epochs of spectroscopy reveal a pair of
transient broad absorption features in the UV on otherwise featureless spectra.
Despite the superficial similarity of these features to P-Cygni absorptions of
supernovae (SNe), we conclude that PS1-11af is not consistent with the
properties of known types of SNe. Blackbody fits to the spectral energy
distribution are inconsistent with the cooling, expanding ejecta of a SN, and
the velocities of the absorption features are too high to represent material in
homologous expansion near a SN photosphere. However, the constant blue colors
and slow evolution of the luminosity are similar to previous optically-selected
tidal disruption events (TDEs). The shape of the optical light curve is
consistent with models for TDEs, but the minimum accreted mass necessary to
power the observed luminosity is only ~0.002M_sun, which points to a partial
disruption model. A full disruption model predicts higher bolometric
luminosities, which would require most of the radiation to be emitted in a
separate component at high energies where we lack observations. In addition,
the observed temperature is lower than that predicted by pure accretion disk
models for TDEs and requires reprocessing to a constant, lower temperature.
Three deep non-detections in the radio with the VLA over the first two years
after the event set strict limits on the production of any relativistic outflow
comparable to Swift J1644+57, even if off-axis.


title: Signal recovery and frames that are robust to erasure

abstract:
  We consider finite frames with high redundancy so that if half the terms
transmitted from the sender are randomly deleted during transmission, then on
average, the receiver can still recover the signal to within a high level of
accuracy. This follows from a result in random matrix theory. We also give an
application of the operator Khintchine inequality in the setting of signal
recovery when the signal is a matrix with a sparse representation.


title: Circular Planar Electrical Networks II: Positivity Phenomena

abstract:
  Curtis-Ingerman-Morrow characterize response matrices for circular planar
electrical networks as symmetric square matrices with row sums zero and
non-negative circular minors. In this paper, we study this positivity
phenomenon more closely, from both algebraic and combinatorial perspectives.
Extending work of Postnikov, we introduce electrical positroids, which are the
sets of circular minors which can simultaneously be positive in a response
matrix. We give a self-contained axiomatic description of these electrical
positroids. In the second part of the paper, we discuss a naturally arising
example of a Laurent phenomenon algebra, as studied by Lam-Pylyavskyy. We
investigate the clusters in this algebra, building off of initial work by
Kenyon-Wilson, using an analogue of weak separation, as was originally
introduced by Leclerc-Zelevinsky.


title:
Phase diagram of microcavity polariton condensates with a harmonic
  potential trap

abstract:
  We theoretically explore the phase transition in inhomogeneous
exciton-polariton condensates with variable pumping conditions. Through
Bogoliubov excitations to the radial-symmetric solutions of complex
Gross-Pitaevskii equation, we determine not only the bifurcation of stable and
unstable modes by the sign of fluid compressibility but also two distinct
stable modes which are characterized by the elementary excitations and the
stability of singly quantized vortex. One state is the quasi-condensate BKT
phase with Goldstone flat dispersion; the other state is the localized-BEC
phase which exhibits linear-type dispersion and has an excitation energy gap at
zero momentum.


title:
The interference effect of laser-assisted bremsstrahlung emission in
  Coulumb fields of two nuclei

abstract:
  In this paper, the spontaneous bremsstrahlung emission from an electron
scattered by two fixed nuclei in an intense laser field is investigated in
details based upon the Volkov state and the Dirac-Volkov propagator. It has
been found that the fundamental harmonic spectrum from the electron radiation
exhibits distinctive fringes, which is dependent not only upon the internucleus
distance and orientation, but also upon the initial energy of the electron and
the laser intensity. By analyzing the differential cross section, we are able
to explain these effects in terms of interference among the electron scattering
by the nuclei. These results could have promising applications in probing the
atomic or molecular dressed potentials in intense laser fields.


title: Hypercontractivity of spherical averages in Hamming space

abstract:
  Consider the linear space of functions on the binary hypercube and the linear
operator $S_\delta$ acting by averaging a function over a Hamming sphere of
radius $\delta n$ around every point. It is shown that this operator has a
dimension-independent bound on the norm $L_p \to L_2$ with $p =
1+(1-2\delta)^2$. This result evidently parallels a classical estimate of
Bonami and Gross for $L_p \to L_q$ norms for the operator of convolution with a
Bernoulli noise. The estimate for $S_\delta$ is harder to obtain since the
latter is neither a part of a semigroup, nor a tensor power. The result is
shown by a detailed study of the eigenvalues of $S_\delta$ and $L_p\to L_2$
norms of the Fourier multiplier operators $\Pi_a$ with symbol equal to a
characteristic function of the Hamming sphere of radius $a$ (in the notation
common in boolean analysis $\Pi_a f=f^{=a}$, where $f^{=a}$ is a degree-$a$
component of function $f$). A sample application of the result is given: Any
set $A\subset \FF_2^n$ with the property that $A+A$ contains a large portion of
some Hamming sphere (counted with multiplicity) must have cardinality a
constant multiple of $2^n$.


title: Some remarks on the minimal model program for log canonical pairs

abstract:
  We prove that the target space of an extremal Fano contraction from a log
canonical pair has only log canonical singularities. We also treat some related
topics, for example, the finite generation of canonical rings for compact
K\"ahler manifolds, and so on. The main ingredient of this paper is the nefness
of the moduli parts of lc-trivial fibrations. We also give some observations on
the semi-ampleness of the moduli parts of lc-trivial fibrations. For the
reader's convenience, we discuss some examples of non-K\"ahler manifolds,
flopping contractions, and so on, in order to clarify our results.


title: Reaction cross sections of hypernuclei and the shrinkage effect

abstract:
  We calculate the reaction cross sections for $^6{\rm Li}$ and
$^7_{\Lambda}{\rm Li}$ on a $^{12}{\rm C}$ target at $100\,{\rm MeV/nucleon}$
using the Glauber theory. To this end, we assume a two-body cluster structure
for $^6$Li and $^7_{\Lambda}{\rm Li}$, and employ the few-body treatment of the
Glauber theory, that is beyond the well known optical limit approximation. We
show that the reaction cross section for $^7_{\Lambda}{\rm Li}$ is smaller than
that for $^6$Li by about 4\%, reflecting the shrinkage effect of the $\Lambda$
particle.


title: Two-photon interference with continuous-wave multi-mode coherent light

abstract:
  We report two-photon interference with continuous-wave multi-mode coherent
light. We show that the two-photon interference, in terms of the detection time
difference, reveals two-photon beating fringes with the visibility $V = 0.5$.
While scanning the optical delay of the interferometer, Hong-Ou-Mandel dips or
peaks are measured depending on the chosen detection time difference. The HOM
dips/peaks are repeated when the optical delay and the first-order coherence
revival period of the multi-mode coherent light are the same.


title:
Recent progress and challenges in exploiting graphics processors in
  computational fluid dynamics

abstract:
  The progress made in accelerating simulations of fluid flow using GPUs, and
the challenges that remain, are surveyed. The review first provides an
introduction to GPU computing and programming, and discusses various
considerations for improved performance. Case studies comparing the performance
of CPU- and GPU- based solvers for the Laplace and incompressible Navier-Stokes
equations are performed in order to demonstrate the potential improvement even
with simple codes. Recent efforts to accelerate CFD simulations using GPUs are
reviewed for laminar, turbulent, and reactive flow solvers. Also, GPU
implementations of the lattice Boltzmann method are reviewed. Finally,
recommendations for implementing CFD codes on GPUs are given and remaining
challenges are discussed, such as the need to develop new strategies and
redesign algorithms to enable GPU acceleration.


title:
Magnetohydrodynamics dynamical relaxation of coronal magnetic fields.
  IV. 3D tilted nulls

abstract:
  In this paper we study current accumulations in 3D "tilted" nulls formed by a
folding of the spine and fan. A non-zero component of current parallel to the
fan is required such that the null's fan plane and spine are not perpendicular.
Our aims are to provide valid magnetohydrostatic equilibria and to describe the
current accumulations in various cases involving finite plasma pressure.To
create our equilibrium current structures we use a full, non-resistive,
magnetohydrodynamic (MHD) code so that no reconnection is allowed. A series of
experiments are performed in which a perturbed 3D tilted null relaxes towards
an equilibrium via real, viscous damping forces. Changes to the initial plasma
pressure and to magnetic parameters are investigated systematically.An
initially tilted fan is associated with a non-zero Lorentz force that drives
the fan and spine to collapse towards each other, in a similar manner to the
collapse of a 2D X-point. In the final equilibrium state for an initially
radial null with only the current perpendicular to the spine, the current
concentrates along the tilt axis of the fan and in a layer about the null point
with a sharp peak at the null itself. The continued growth of this peak
indicates that the system is in an asymptotic regime involving an infinite time
singularity at the null. When the initial tilt disturbance (current
perpendicular to the spine) is combined with a spiral-type disturbance (current
parallel to the spine), the final current density concentrates in three
regions: one on the fan along its tilt axis and two around the spine, above and
below the fan. The increased area of current accumulation leads to a weakening
of the singularity formed at the null. The 3D spine-fan collapse with generic
current studied here provides the ideal setup for non-steady reconnection
studies.


title:
High-efficiency single-photon Fock state production by transitionless
  quantum driving

abstract:
  Single photon source is one of the key devices for optical quantum
information processing. Differing from the usual stimulated Raman adiabatic
passage to obtain single-photon radiation, here we propose an approach to
produce optical Fock state on demand in the usual atom-cavity system by
utilizing the technique of transitionless quantum driving. The present proposal
effectively suppresses the unwanted but practically unavoidable nonadiabatic
transitions in the previous adiabatic schemes. Therefore, the efficiency of
Fock state production by the present technique could be significantly high,
even in the presence of various atomic and cavity dissipations.


title:
Self-Organized Vortices of Circling Self-Propelled Particles and Curved
  Active Flagella

abstract:
  Self-propelled point-like particles move along circular trajectories when
their translocation velocity is constant and the angular velocity related to
their orientation vector is also constant. We investigate the collective
behavior of ensembles of such circle swimmers by Brownian dynamics simulations.
If the particles interact via a "velocity-trajectory coordination" rule within
neighboring particles, a self-organized vortex pattern emerges. This vortex
pattern is characterized by its particle-density correlation function $G_\rho$,
the density correlation function $G_c$ of trajectory centers, and an order
parameter $S$ representing the degree of the aggregation of the particles.
Here, we systematically vary the system parameters, such as the particle
density and the interaction range, in order to reveal the transition of the
system from a light-vortex-dominated to heavy-vortex-dominated state, where
vortices contain mainly a single and many self-propelled particles,
respectively. We also study a semi-dilute solution of curved,
sinusoidal-beating flagella, as an example of circling self-propelled particles
with explicit propulsion mechanism and excluded-volume interactions. Our
simulation results are compared with previous experimental results for the
vortices in sea-urchin sperm solutions near a wall. The properties of the
vortices in simulations and experiments are found to agree quantitatively.


title:
A penalization approach to linear programming duality with application
  to capacity constrained transport

abstract:
  A new approach to linear programming duality is proposed which relies on
quadratic penalization, so that the relation between solutions to the penalized
primal and dual problems becomes affine. This yields a new proof of Levin's
duality theorem for capacity-constrained optimal transport as an
infinite-dimensional application.


title:
Quantum memories with electrically controlled storage and retrieval in
  an opto- and electro-mechanical cavity

abstract:
  We propose a novel scheme to realize electrically controlled quantum memories
in the opto- and electro-mechanical (OEM) cavity. Combining this OEM cavity
with the mechanism of Electromagnetically Induced Transparency (EIT) we find
that the quantum interference, arising from the two optical transitions of the
$\Lambda$ type three-level atomic ensembles, can be manipulated electrically.
Numerical calculations show that the probe photon state can be well stored into
the atomic spin state by sending an electric current pulse and retrieved with
time-reverse symmetry by sending the other current pulse with opposite
direction. The quantum interference with electric controlling is expected to
apply to other quantum control aspects.


title:
Gauge invariant composite operators of QED in the exact renormalization
  group formalism

abstract:
  Using the exact renormalization group (ERG) formalism, we study the gauge
invariant composite operators in QED. Gauge invariant composite operators are
introduced as infinitesimal changes of the gauge invariant Wilson action. We
examine the dependence on the gauge fixing parameter of both the Wilson action
and gauge invariant composite operators. After defining ``gauge fixing
parameter independence,'' we show that any gauge independent composite
operators can be made ``gauge fixing parameter independent'' by appropriate
normalization. As an application, we give a concise but careful proof of the
Adler-Bardeen non-renormalization theorem for the axial anomaly in an arbitrary
covariant gauge by extending the original proof by A. Zee.


title:
Disorder effects in multiorbital $s_{\pm}$-wave superconductors:
  Implications for Zn-doped BaFe$_2$As$_2$ compounds

abstract:
  Recent experiments on Zn-doped 122-type iron pnictides,
Ba(Fe$_{1-x-y}$Co$_y$Zn$_x$)$_2$As$_2$, are challenging our understanding of
electron doping the 122s and the interplay between doping and impurity
scattering. To resolve this enigma, we investigate the disorder effects of
nonmagnetic Zn impurities in the strong (unitary) scattering limit on various
properties of the system in the $s_{\pm}$-wave superconducting pairing state.
The lattice Bogoliubov-de Gennes equation (BdG) is solved self-consistently
based on a minimal two-orbital model with an extended range of impurity
concentrations. We find that Zn impurity is best modeled as a defect, where
charge is mainly localized, but scattering is extended over a few lattice
sites. With increasing Zn concentration the density of states shows a gradual
filling of the gap, revealing the impurity-induced pair breaking effect.
Moreover, both the disorder configuration-averaged superconducting order
parameter and the superfluid density are dramatically suppressed towards the
dirty limit, indicating the violation of the Anderson theorem for conventional
s-wave superconductors and the breakdown of the Abrikosov-Gorkov theory for
impurity-averaged Green's functions. Furthermore, we find that the
superconducting phase is fully suppressed close to the critical impurity
concentration of roughly $n_\text{imp}\approx 10%$, in agreement with recent
experiments.


title:
Orbit equivalence and Borel reducibility rigidity for profinite actions
  with spectral gap

abstract:
  We study equivalence relations $\mathcal R(\Gamma\curvearrowright G)$ that
arise from left translation actions of countable groups on their profinite
completions. Under the assumption that the action $\Gamma\curvearrowright G$ is
free and has spectral gap, we describe precisely when $\mathcal
R(\Gamma\curvearrowright G)$ is orbit equivalent or Borel reducible to another
such equivalence relation $\mathcal R(\Lambda\curvearrowright H)$. As a
consequence, we provide explicit uncountable families of free ergodic
probability measure preserving (p.m.p.) profinite actions of $SL_2(\mathbb Z)$
and its non-amenable subgroups (e.g. $\mathbb F_n$, with $2\leqslant
n\leqslant\infty$) whose orbit equivalence relations are mutually not orbit
equivalent and not Borel reducible. In particular, we show that if $S$ and $T$
are distinct sets of primes, then the orbit equivalence relations associated to
the actions $SL_2(\mathbb Z)\curvearrowright\prod_{p\in S}SL_2(\mathbb Z_p)$
and $SL_2(\mathbb Z)\curvearrowright\prod_{p\in T}SL_2(\mathbb Z_p)$ are
neither orbit equivalent nor Borel reducible. This settles a conjecture of S.
Thomas \cite{Th06}. Other applications include the first calculations of outer
automorphism groups for concrete treeable p.m.p. equivalence relations, and the
first concrete examples of free ergodic p.m.p. actions of $\mathbb F_{\infty}$
whose orbit equivalence relations have trivial fundamental group.


title: The theory of coherent dynamic nuclear polarization in quantum dots

abstract:
  We consider the dynamic nuclear spin polarization (DNP) using two electrons
in a double quantum dot in presence of external magnetic field and spin-orbit
interaction, in various schemes of periodically repeated sweeps through the
S-T+ avoided crossing. By treating the problem semi-classically, we find that
generally the DNP have two distinct contributions - a geometrical polarization
and a dynamic polarization, which have different dependence on the control
parameters such as the sweep rates and waiting times in each period. Both terms
show non-trivial dependence on those control parameter. We find that even for
small spin-orbit term, the dynamical polarization dominates the DNP in presence
of a long waiting period near the S-T+ avoided crossing, of the order of the
nuclear Larmor precession periods. A detailed numerical analysis of a specific
control regime can explain the oscillations observed by Foletti et.~al.~in
arXiv:0801.3613.


title: Permutation Statistics and Multiple Pattern Avoidance

abstract:
  For a set of permutation patterns $\Pi$, let $F^\text{st}_n(\Pi,q)$ be the
st-polynomial of permutations avoiding all patterns in $\Pi$. Suppose
$312\in\Pi$. For a class of permutation statistics which includes inversion and
descent statistics, we give a formula that expresses $F^\text{st}_n(\Pi;q)$ in
terms of these st-polynomials where we take some subblocks of the patterns in
$\Pi$. Using this formula, we can construct many examples of nontrivial st-Wilf
equivalences. In particular, this disproves a conjecture by Dokos, Dwyer,
Johnson, Sagan, and Selsor that all $\text{inv}$-Wilf equivalences are trivial.


title:
On the Chi square and higher-order Chi distances for approximating
  f-divergences

abstract:
  We report closed-form formula for calculating the Chi square and higher-order
Chi distances between statistical distributions belonging to the same
exponential family with affine natural space, and instantiate those formula for
the Poisson and isotropic Gaussian families. We then describe an analytic
formula for the $f$-divergences based on Taylor expansions and relying on an
extended class of Chi-type distances.


title:
Effects of Geometry and Symmetry on Electron Transport through
  Graphene-Carbon-Chain Junctions

abstract:
  The electron transport between two zigzag graphene nanoribbons (ZGNRs)
connected by carbon atomic chains has been investigated by the nonequilibrium
Green's function method combined with the density functional theory. The
symmetry of the orbitals in the carbon chain selects critically the modes and
energies of the transporting electrons. The electron transport near the Fermi
energy can be well-manipulated by the position and the number of carbon chains
contacting the nanoribbons. In symmetric ZGNRs connected by a central carbon
chain, a square conductance step appears at the Fermi energy because the
antisymmetric modes below it are not allowed to go through the chain. These
modes can additionally contribute to the conductance if side carbon chains are
added in the connection. By choosing a proper geometry configuration, we can
realize Ohmic contact, current stabilizer, or the negative differential
resistance phenomenon in the devices.


title: Quantum modified Regge-Teitelboim cosmology

abstract:
  The canonical quantization of the modified geodetic brane cosmology which is
implemented from the Regge-Teitelboim model and the trace of the extrinsic
curvature of the brane trajectory, K, is developed. As a second-order
derivative model, on the grounds of the Ostrogradski Hamiltonian method and the
Dirac's scheme for constrained systems, we find suitable first- and
second-class constraints which allow for a proper quantization. We also find
that the first-class constraints obey a sort of truncated Virasoro algebra. The
effective quantum potential emerging in our approach is exhaustively studied
where it shows that an embryonic epoch is still present. The quantum nucleation
is sketched where we observe that it is driven by an effective cosmological
constant.


title:
Study of some improved ratio type estimators using information on
  auxiliary attributes under second order approximation

abstract:
  Chakrabarty, Khoshnevisan, Sahai and Ray, Solanki suggested some estimators
to estimate unknown population mean of the study variable. These authors
discussed the estimators along with their first order biases and mean square
errors(MSEs). In this paper, we have tried to found out the second order biases
and mean square errors of some estimators using information on auxiliary
attribute. We have compared the performance of the estimators with the help of
a numerical illustration.


title: The Koszul property of pinched Veronese varieties

abstract:
  Let $K$ be an arbitrary field. Let $n,d \ge 2$ be positive integers. Let
$V(n,d)$ be the set of all lattice points $\mathbf b = (b_1, ..., b_n)$ in
${\mathbb N}^n$ such that $\sum_{i=1}^n b_i = d$. Let $\Gamma = V(n,d)
\setminus \{ \mathbf a \}$ for some element $\mathbf a \in V(n,d)$. In this
paper we prove that the semigroup ring $K[\Gamma]$ is Koszul unless $d \ge 3$
and ${\mathbf a} = (0, ...,0, 2, d-2)$ or one of its permutations. This
generalizes results of Caviglia, Conca, and Tancer.