title:
Narrow-line region gas kinematics of 24,264 optically-selected AGN: the
  radio connection

abstract:
  Using a sample of 24264 optically selected AGNs from the SDSS DR7 database,
we characterise how the profile of the [OIII] emission line relates to
bolometric luminosity (L_Bol), Eddington ratio, radio loudness, radio
luminosity (L_Rad) and optical class (Sy 1/2) to determine what drives the
kinematics of this kpc-scale line emitting gas. Spectral stacking is used to
characterise how the average [OIII] profile changes as a function of these
variables. After accounting for the correlation between L_Bol and L_Rad, we
report that L_Rad has the strongest influence on the [OIII] profile, with
moderate radio luminosity AGNs (log(L_Rad)=23-25 W/Hz) having the broadest
[OIII] profiles. When binned according to Eddington ratio, only AGNs in our
highest bin (i.e., R_Edd>0.3) show any signs of having broadened [OIII]
profiles, although the small numbers of such extreme AGNs mean we cannot rule
out that other processes (e.g., radio jets) are responsible for this
broadening. We find no significant difference between the [OIII] profiles of
broad and narrow-line Seyfert 1s. The [OIII] profiles of Sy 1 and 2 AGNs show
the same trends in terms of line width, but Sy 1 AGNs display a much stronger
blue wing, which we interpret as evidence of outflowing ionised gas. Using
multi-component line fitting we calculate the proportions of AGNs with broad
[OIII] profiles, finding that moderate radio luminosity AGNs are roughly 5
times more likely to have extremely broad [OIII] lines (FWHM>1000km/s) compared
to lower L_Rad AGNs. Our results are consistent with the most disturbed gas
kinematics being induced by compact radio cores (rather than powerful radio
jets), although broadened [OIII] lines are also present, but much rarer, in low
L_Rad systems (<10^23 W/Hz). Our catalogue of multi-component fits is freely
available as an online resource.


title:
Tests of Lorentz Invariance Violation with Gamma Rays to probe Quantum
  Gravity

abstract:
  We discuss the prospects of doing tests of Lorentz invariance with gamma-rays
observed with present and future ground based gamma-ray observatories.


title: A Double White-Dwarf Cooling Sequence in {\omega} Centauri

abstract:
  We have applied our empirical-PSF-based photometric techniques on a large
number of calibration-related WFC3/UVIS UV-B exposures of the core of {\omega}
Cen, and found a well-defined split in the right part of the white-dwarf
cooling sequence (WDCS). The redder sequence is more populated by a factor of
~2. We can explain the separation of the two sequences and their number ratio
in terms of the He-normal and He-rich subpopulations that had been previously
identified along the cluster main sequence. The blue WDCS is populated by the
evolved stars of the He-normal component (~0.55 Msun CO-core DA objects) while
the red WDCS hosts the end-products of the He-rich population (~0.46 Msun
objects, ~10% CO-core and ~90% He-core WDs). The He-core WDs correspond to
He-rich stars that missed the central He-ignition, and we estimate their
fraction by analyzing the population ratios along the cluster horizontal
branch.


title: 2d Index and Surface operators

abstract:
  In this paper we compute the superconformal index of 2d (2,2) supersymmetric
gauge theories. The 2d superconformal index, a.k.a. flavored elliptic genus, is
computed by a unitary matrix integral much like the matrix integral that
computes 4d superconformal index. We compute the 2d index explicitly for a
number of examples. In the case of abelian gauge theories we see that the index
is invariant under flop transition and CY-LG correspondence. The index also
provides a powerful check of the Seiberg-type duality for non-abelian gauge
theories discovered by Hori and Tong.
  In the later half of the paper, we study half-BPS surface operators in N=2
superconformal gauge theories. They are engineered by coupling the 2d (2,2)
supersymmetric gauge theory living on the support of the surface operator to
the 4d N=2 theory, so that different realizations of the same surface operator
with a given Levi type are related by a 2d analogue of the Seiberg duality. The
index of this coupled system is computed by using the tools developed in the
first half of the paper. The superconformal index in the presence of surface
defect is expected to be invariant under generalized S-duality. We demonstrate
that it is indeed the case. In doing so the Seiberg-type duality of the 2d
theory plays an important role.


title: The Kinematics of Cosmic Reheating

abstract:
  We calculate the relaxation rate of a scalar field in a plasma of other
scalars and fermions with gauge interactions using thermal quantum field
theory. It yields the rate of cosmic reheating and thereby determines the
temperature of the "hot big bang" in inflationary cosmology. The total rate
originates from various processes, including decays and inverse decays as well
as Landau damping by scatterings. It involves quantum statistical effects and
off-shell transport. Its temperature dependence can be highly nontrivial,
making it impossible to express the reheating temperature in terms of the model
parameters in a simple way. We pay special attention to the temperature
dependence of the phase space due to the modified dispersion relations in the
plasma. We find that it can have a drastic effect on the efficiency of
perturbative reheating, which depends on the way particles in the primordial
plasma interact. For some interactions thermal masses can effectively close the
phase space for the dominant dissipative processes and thereby impose an upper
bound on the reheating temperature. In other cases they open up new channels of
dissipation, hence increase the reheating temperature. At high temperatures we
find that the universe can even be heated through couplings to fermions, which
are often assumed to be negligible due to Pauli-blocking. These effects may
also be relevant for baryogenesis, dark matter production, the fate of moduli
and in scenarios of warm inflation.


title:
SINFONI/VLT 3D spectroscopy of massive galaxies: Evidence of rotational
  support at z~1.4

abstract:
  There is cumulative evidence showing that, for the most massive galaxies, the
fraction of disk-like objects compared to those with spheroidal properties
increases with redshift. However, this evolution is thus far based on the
surface brightness study of these objects. To explore the consistency of this
scenario, it is necessary to measure the dynamical status of these galaxies.
With this aim we have obtained seeing-limited near-infrared integral field
spectra in the H-band for 10 massive galaxies (M_{stellar} >10^{11} h_{70}^-2
M_{Sun}) at z~1.4 with SINFONI at the VLT. Our sample is selected by their
stellar mass and EW[OII] > 15 \AA, to secure their kinematic measurements, but
without accounting for any morphological or flux criteria a priori. Through
this 3D kinematic spectroscopy analysis we find that half (i.e. 50+/-7%) of our
galaxies are compatible with being rotationally supported disks, in agreement
with previous morphological expectations. This is a factor of approximately two
higher than what is observed in the present Universe for objects of the same
stellar mass. Strikingly, the majority of our sample of massive galaxies show
extended and fairly high rotational velocity maps, implying that massive
galaxies acquire rapidly rotational support and hence gravitational
equilibrium. Our sample also show evidence for ongoing interactions and
mergers. Summarizing, massive galaxies at high-z show a significant diversity
and must have continued evolution beyond the fading of stellar populations, to
become their present day counterparts.


title:
The Role of Core Mass in Controlling Evaporation: the Kepler Radius
  Distribution and the Kepler-36 Density Dichotomy

abstract:
  We use models of coupled thermal evolution and photo-evaporative mass loss to
understand the formation and evolution of the Kepler-36 system. We show that
the large contrast in mean planetary density observed by Carter et al. (2012)
can be explained as a natural consequence of photo-evaporation from planets
that formed with similar initial compositions. However, rather than being due
to differences in XUV irradiation between the planets, we find that this
contrast is due to the difference in the masses of the planets' rock/iron cores
and the impact that this has on mass loss evolution. We explore in detail how
our coupled models depend on irradiation, mass, age, composition, and the
efficiency of mass loss. Based on fits to large numbers of coupled evolution
and mass loss runs, we provide analytic fits to understand threshold XUV fluxes
for significant atmospheric loss, as a function of core mass and mass loss
efficiency. Finally we discuss these results in the context of recent studies
of the radius distribution of Kepler candidates. Using our parameter study, we
make testable predictions for the frequency of sub-Neptune sized planets. We
show that 1.8-4.0 R_earth planets should become significantly less common on
orbits within 10 days and discuss the possibility of a narrow "occurrence
valley" in the radius-flux distribution. Moreover, we describe how
photo-evaporation provides a natural explanation for the recent observations of
Ciardi et al. (2013) that inner planets are preferentially smaller within the
systems.


title:
ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo~P. II. Optical
  Imaging Observations

abstract:
  We present results from ground-based optical imaging of a low-mass dwarf
galaxy discovered by the ALFALFA 21-cm HI survey. Broadband (BVR) data obtained
with the WIYN 3.5-m telescope at Kitt Peak National Observatory (KPNO) are used
to construct color-magnitude diagrams of the galaxy's stellar population down
to V_0 ~ 25. We also use narrowband H-alpha imaging from the KPNO 2.1-m
telescope to identify an HII region in the galaxy. We use these data to
constrain the distance to the galaxy to be between 1.5 and 2.0 Mpc. This places
Leo P within the Local Volume but beyond the Local Group. Its properties are
extreme: it is the lowest-mass system known that contains significant amounts
of gas and is currently forming stars.


title: Mixed Galileons and Spherically Symmetric Solutions

abstract:
  It was previously found that in a certain parameter subspace of scalar-tensor
theories emerging from massive gravity, the only stable field configuration
created by static spherically symmetric sources was one with cosmological
asymptotics. Moreover, these backgrounds were shown to be sub-luminal
everywhere in the space; in contrast to the common believe that these theories
are necessarily superluminal in the vicinity of a static source. In this work
we complete that analysis by extending it to cover the whole parameter space of
these scalar-tensor theories. We find that the stability argument renders the
asymptotically flat backgrounds unrealizable, forcing once again for
cosmological asymptotics. In the case of pressureless sources these backgrounds
are stable. However, they get destabilized in the presence of positive
pressure, larger than a critical density. Even on the self-accelerated
background, on which the scalar mode decouples from sources, in the region
occupied by the source it acquires an elliptic equation of motion. Therefore,
we conclude that the only parameter space which is not ruled out, by solar
system measurements, is the one considered in Berezhiani {\it et al.}
(arXiv:1302.0549), namely the one for which the scalar and tensor modes can be
diagonalized via local transformations. We also reinvestigate the scale at
which perturbation theory breaks down in a general Galileon theory. We show
that the Vainshtein mechanism successfully redresses the strong coupling scale
to a small one, just like in the cubic Galileon, despite the cancellations
occurring in the special spherically symmetric case. We emphasize that even if
these tests were performed at scales at which perturbation theory broke down,
these could not be interpreted as a lower bound for the graviton mass.


title:
ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo P. I. HI
  Observations

abstract:
  The discovery of a previously unknown 21cm HI line source identified as an
ultra-compact high velocity cloud in the ALFALFA survey is reported. The HI
detection is barely resolved by the Arecibo 305m telescope ~4' beam and has a
narrow HI linewidth (HPFW of 24 km/s). Further HI observations at Arecibo and
with the VLA corroborate the ALFALFA HI detection, provide an estimate of the
HI radius, ~1' at the 5 x 10^19 cm^-2 isophote, and show the cloud to exhibit
rotation with an amplitude of ~9.0 +/- 1.5 km/s. In other papers, Rhode et al.
(2013) show the HI source to have a resolved stellar counterpart and ongoing
star forming activity, while Skillman et al. (2013) reveal it as having
extremely low metallicity: 12 + log(O/H) = 7.16 +/- 0.04. The HI mass to
stellar mass ratio of the object is found to be 2.6. We use the Tully-Fisher
template relation in its baryonic form (McGaugh 2012) to obtain a distance
estimate D = 1.3 (+0.9,-0.5) Mpc. Additional constraints on the distance are
also provided by the optical data of Rhode et al. (2013) and McQuinn et al.
(private communication), both indicating a distance in the range of 1.5 to 2.0
Mpc. The three estimates are compatible within their errors. The object appears
to be located beyond the dynamical boundaries of, but still in close proximity
to the Local Group. Its pristine properties are consistent with the sedate
environment of its location. At a nominal distance of 1.75 Mpc, it would have
an HI mass of ~1.0 x 10^6 Msun, a stellar mass of ~3.6 x 10^5 Msun, and a
dynamical mass within the HI radius of ~1.5 x 10^7 Msun. This discovery
supports the idea that optically faint - or altogether dark - low mass halos
may be detectable through their non-stellar baryons.


title: Glueball and meson propagators of any spin in large-N QCD

abstract:
  We prove an asymptotic structure theorem for glueball and meson propagators
of any spin in large-N QCD and in n=1 SUSY QCD with massless quarks, that
determines asymptotically the residues of the poles of the propagators in terms
of their anomalous dimensions and of the spectral density of the masses. The
asymptotic theorem follows by the severe constraints on the propagators in
large-N QCD with massless quarks, or in any large-N confining
asymptotically-free gauge theory massless in perturbation theory, that arise by
perturbation theory in conjunction with the renormalization group and by the
OPE on the ultraviolet side. The asymptotic theorem is inspired by a recently
proposed Topological Field Theory (TFT) underlying large-N pure YM, that
computes sums of the scalar and of the pseudoscalar correlators satisfying the
asymptotic theorem and that implies for the large-N joint scalar and
pseudoscalar glueball spectrum exact linearity in the masses squared. On the
infrared side we test the prediction of the exact linearity in the TFT by
Meyer-Teper lattice numerical computation of the masses of the low-lying
glueballs in SU(8) YM, finding accurate agreement. Besides, we employ the
aforementioned ultraviolet and infrared constraints in order to compare
critically the scalar or pseudoscalar glueball propagators computed in the
framework of the AdS String/large-N Gauge Theory correspondence with those of
the TFT underlying large-N YM. We find that only the TFT satisfies the
ultraviolet and infrared constraints.


title: Multichannel Deconvolution with Long-Range Dependence: A Minimax Study

abstract:
  We consider the problem of estimating the unknown response function in the
multichannel deconvolution model with long-range dependent Gaussian errors. We
do not limit our consideration to a specific type of long-range dependence
rather we assume that the errors should satisfy a general assumption in terms
of the smallest and larger eigenvalues of their covariance matrices. We derive
minimax lower bounds for the quadratic risk in the proposed multichannel
deconvolution model when the response function is assumed to belong to a Besov
ball and the blurring function is assumed to possess some smoothness
properties, including both regular-smooth and super-smooth convolutions.
Furthermore, we propose an adaptive wavelet estimator of the response function
that is asymptotically optimal (in the minimax sense), or near-optimal within a
logarithmic factor, in a wide range of Besov balls. It is shown that the
optimal convergence rates depend on the balance between the smoothness
parameter of the response function, the kernel parameters of the blurring
function, the long memory parameters of the errors, and how the total number of
observations is distributed among the total number of channels. Some examples
of inverse problems in mathematical physics where one needs to recover initial
or boundary conditions on the basis of observations from a noisy solution of a
partial differential equation are used to illustrate the application of the
theory we developed. The optimal convergence rates and the adaptive estimators
we consider extend the ones studied by Pensky and Sapatinas (2009, 2010) for
independent and identically distributed Gaussian errors to the case of
long-range dependent Gaussian errors.


title: Magneto-optical conductivity of Weyl semimetals

abstract:
  Weyl semimetals are a topological phase of matter that have drawn recent
interest and have been suggested as a possible phase of the pyrochlore
irridates, among other materials. Here, we compute the magneto-optical response
of an isolated Weyl point. We find that the conductivity is a series of
asymmetric peaks lying on top of a linear background. We find additional
features in the conductivity that are explained by the underlying Landau level
structure. We show that weak disorder tends to blur out the peaks, but they
still show up as measurable oscillations on a linear background.


title:
Constraint on the Polarization of Electric Dipole Emission from Spinning
  Dust

abstract:
  Planck results have revealed that the electric dipole emission from
polycyclic aromatic hydrocarbons (PAHs) is the most reliable explanation for
anomalous microwave emission that interferes with cosmic microwave background
(CMB) radiation experiments. The emerging question is to what extent this
emission component contaminates to the polarized CMB radiation. We present
constraints on polarized dust emission for the model of grain size distribution
and grain alignment that best fits to observed extinction and polarization
curves. Two stars with a prominent polarization feature at wavelength 2175
Angstrom, HD 197770 and HD 147933-4, are chosen for our study. For HD 197770,
we find that the model with aligned silicate grains plus weakly aligned PAHs
can successfully reproduce the 2175 Angstrom polarization feature; whereas, for
HD 147933-4, we find that the alignment of only silicate grains can account for
that feature. The alignment function of PAHs for the best-fit model to the HD
197770 data is employed to constrain polarized spinning dust emission. We find
that the degree of polarization of spinning dust emission is about 1.6 percent
at frequency ~ 3 GHz and declines to below 0.9 percent for frequency above 20
GHz. We also predict the degree of polarization of thermal dust emission at 353
GHz to be ~ 11 percent and 14 percent for the lines of sight to the HD 197770
and HD 147933-4 stars, respectively.


title:
ALFALFA Discovery of the Nearby Gas-Rich Dwarf Galaxy Leo~P. III. An
  Extremely Metal Deficient Galaxy

abstract:
  We present KPNO 4-m and LBT/MODS spectroscopic observations of an HII region
in the nearby dwarf irregular galaxy Leo P discovered recently in the Arecibo
ALFALFA survey. In both observations, we are able to accurately measure the
temperature sensitive [O III] 4363 Angstrom line and determine a "direct"
oxygen abundance of 12 + log(O/H) = 7.17 +/- 0.04. Thus, Leo P is an extremely
metal deficient (XMD) galaxy, and, indeed, one of the most metal deficient
star-forming galaxies ever observed. For its estimated luminosity, Leo P is
consistent with the relationship between luminosity and oxygen abundance seen
in nearby dwarf galaxies. Leo P shows normal alpha element abundance ratios
(Ne/O, S/O, and Ar/O) when compared to other XMD galaxies, but elevated N/O,
consistent with the "delayed release" hypothesis for N/O abundances. We derive
a helium mass fraction of 0.2509 +0.0184 -0.0123 which compares well with the
WMAP + BBN prediction of 0.2483 +/- 0.0002 for the primordial helium abundance.
We suggest that surveys of very low mass galaxies compete well with emission
line galaxy surveys for finding XMD galaxies. It is possible that XMD galaxies
may be divided into two classes: the relatively rare XMD emission line galaxies
which are associated with starbursts triggered by infall of low-metallicity gas
and the more common, relatively quiescent XMD galaxies like Leo P, with very
low chemical abundances due to their intrinsically small masses.


title:
Searching for Topological Degeneracy in the Hubbard Model with Quantum
  Monte Carlo

abstract:
  Z2 spin liquids have topological order. One manifestation of this is that a
Z2 spin liquid on a torus exhibits a four-fold degeneracy. Recent numerical
evidence has argued for the existence of a spin liquid ground state in the
Hubbard model on a honeycomb lattice near U approximately 4. The evidence for
this claim involves the presence of a gapped state that lacks any identifiable
order. This argument relies on being able to distinguish small order from no
order which is notoriously difficult. In this paper we demonstrate an approach
which uses quantum Monte Carlo to search for one of the key features that
positively identify the topological spin liquid: the topological degeneracy.
For any finite system, this topological degeneracy is split where the splitting
decays exponentially with system size. We search for low lying states in the
energy spectrum that could be identified as these topologically degenerate
states. We show that, for system sizes up to N=162 sites, there is no evidence
for these states being significantly below the first excited state giving
evidence against the existence of a topological phase. We discuss the possible
options for the Hubbard model on the honeycomb lattice in the absence of such
degeneracy.


title: Effective theory for the Vainshtein mechanism from the Horndeski action

abstract:
  Starting from the general Horndeski action, we derive the most general
effective theory for scalar perturbations around flat space that allows us to
screen fifth forces via the Vainshtein mechanism. The effective theory is
described by a generalization of the Galileon Lagrangian, which we use to study
the stability of spherically symmetric configurations exhibiting the Vainshtein
effect. In particular, we discuss the phenomenological consequences of a
scalar-tensor coupling that is absent in the standard Galileon Lagrangian. This
coupling controls the superluminality and stability of fluctuations inside the
Vainshtein radius in a way that depends on the density profile of a matter
source. Particularly we find that the vacuum solution is unstable due to this
coupling.


title:
MARVELS-1: A face-on double-lined binary star masquerading as a resonant
  planetary system; and consideration of rare false positives in radial
  velocity planet searches

abstract:
  We have analyzed new and previously published radial velocity observations of
MARVELS-1, known to have an ostensibly substellar companion in a ~6- day orbit.
We find significant (~100 m/s) residuals to the best-fit model for the
companion, and these residuals are naively consistent with an interior giant
planet with a P = 1.965d in a nearly perfect 3:1 period commensuribility
(|Pb/Pc - 3| < 10^{-4}). We have performed several tests for the reality of
such a companion, including a dynamical analysis, a search for photometric
variability, and a hunt for contaminating stellar spectra. We find many reasons
to be critical of a planetary interpretation, including the fact that most of
the three-body dynamical solutions are unstable. We find no evidence for
transits, and no evidence of stellar photometric variability. We have
discovered two apparent companions to MARVELS-1 with adaptive optics imaging at
Keck; both are M dwarfs, one is likely bound, and the other is likely a
foreground object. We explore false-alarm scenarios inspired by various
curiosities in the data. Ultimately, a line profile and bisector analysis lead
us to conclude that the ~100 m/s residuals are an artifact of spectral
contamination from a stellar companion contributing ~15-30% of the optical
light in the system. We conclude that origin of this contamination is the
previously detected radial velocity companion to MARVELS-1, which is not, as
previously reported, a brown dwarf, but in fact a G dwarf in a face-on orbit.


title:
Role of magnetic field strength and numerical resolution in simulations
  of the heat-flux driven buoyancy instability

abstract:
  The role played by magnetic fields in the intracluster medium (ICM) of galaxy
clusters is complex. The weakly collisional nature of the ICM leads to thermal
conduction that is channelled along field lines. This anisotropic heat
conduction profoundly changes the stability of the ICM atmosphere, with
convective stabilities being driven by temperature gradients of either sign.
Here, we employ the Athena magnetohydrodynamic code to investigate the local
non-linear behavior of the heat-flux driven buoyancy instability (HBI),
relevant in the cores of cooling-core clusters where the temperature increases
with radius. We study a grid of 2-d simulations that span a large range of
initial magnetic field strengths and numerical resolutions. For very weak
initial fields, we recover the previously known result that the HBI wraps the
field in the horizontal direction thereby shutting off the heat flux. However,
we find that simulations which begin with intermediate initial field strengths
have a qualitatively different behavior, forming HBI-stable filaments that
resist field-line wrapping and enable sustained vertical conductive heat flux
at a level of 10--25% of the Spitzer value. While astrophysical conclusions
regarding the role of conduction in cooling cores require detailed global
models, our local study proves that systems dominated by HBI do not necessarily
quench the conductive heat flux.


title: Densities and energies of nuclei in dilute matter

abstract:
  We explore the ground-state properties of nuclear clusters embedded in a gas
of nucleons with the help of Skyrme-Hartree-Fock microscopic calculations. Two
alternative representations of clusters are introduced, namely coordinate-space
and energy-space clusters. We parameterize their density profiles in spherical
symmetry in terms of basic properties of the energy density functionals used
and propose an analytical, Woods-Saxon density profile whose parameters depend,
not only on the composition of the cluster, but also of the nucleon gas. We
study the clusters' energies with the help of the local-density approximation,
validated through our microscopic results. We find that the volume energies of
coordinate-space clusters are determined by the saturation properties of
matter, while the surface energies are strongly affected by the presence of the
gas. We conclude that both the density profiles and the cluster energies are
strongly affected by the gas and discuss implications for the nuclear EoS and
related perspectives. Our study provides a simple, but microscopically
motivated modeling of the energetics of clusterized matter at subsaturation
densities, for direct use in consequential applications of astrophysical
interest.


title:
Fully Perturbative Calculation of $nd$ Scattering to
  Next-to-next-to-leading-order

abstract:
  We introduce a new technique to calculate perturbative corrections to
neutron-deuteron ($nd$) scattering that does not require calculation of the
full off-shell scattering amplitude. Its relation to the more familiar
partial-resummation technique is explained. Also included is a calculation of
the SD-mixing term that occurs at next-to-next-to-leading-order (NNLO) in
pionless effective field theory $\mathrm{EFT}_{\not{\pi}}$\xspace. Using the
new technique with the SD-mixing term a complete strictly perturbative
phase-shift analysis of $nd$ scattering is performed up to NNLO including
eigen-phases and mixing angles. This is compared to potential model
calculations and good agreement is found with the eigen-phases and some of the
mixing angles at low energies.


title: Connecting $p$-gonal loci in the compactification of moduli space

abstract:
  Consider the moduli space $\mathcal{M}_{g}$ of Riemann surfaces of genus
$g\geq 2$ and its Deligne-Munford compactification $\bar{\mathcal{M}_{g}}$. We
are interested in the branch locus ${\mathcal{B}_{g}}$ for $g>2$, i.e., the
subset of $\mathcal{M}_{g}$ consisting of surfaces with automorphisms. It is
well-known that the set of hyperelliptic surfaces (the hyperelliptic locus) is
connected in $\mathcal{M}_{g}$ but the set of (cyclic) trigonal surfaces is
not. By contrast, we show that for $g\geq 5$ the set of (cyclic) trigonal
surfaces is connected in $\bar{\mathcal{M}_{g}}$. To do so we exhibit an
explicit nodal surface that lies in the completion of every equisymmetric set
of 3-gonal Riemann surfaces. For $p>3$ the connectivity of the $p$-gonal loci
becomes more involved. We show that for $p\geq 11$ prime and genus $g=p-1$
there are one-dimensional strata of cyclic $p$-gonal surfaces that are
completely isolated in the completion $\bar{\mathcal{B}_{g}}$ of the branch
locus in $\bar{\mathcal{M}_{g}}$.


title: Odometer actions of the Heisenberg group

abstract:
  Let $H_3(\Bbb R)$ denote the 3-dimensional real Heisenberg group. Given a
family of lattices $\Gamma_1\supset\Gamma_2\supset\cdots$ in it, let $T$ stand
for the associated uniquely ergodic $H_3(\Bbb R)$-{\it odometer}, i.e. the
inverse limit of the $H_3(\Bbb R)$-actions by rotations on the homogeneous
spaces $H_3(\Bbb R)/\Gamma_j$, $j\in\Bbb N$. The decomposition of the
underlying Koopman unitary representation of $H_3(\Bbb R)$ into a countable
direct sum of irreducible components is explicitly described. The ergodic
2-fold self-joinings of $T$ are found. It is shown that in general, the
$H_3(\Bbb R)$-odometers are neither isospectral nor spectrally determined.


title: Cosmological growth and feedback from supermassive black holes

abstract:
  We develop a simple evolutionary scenario for the growth of supermassive
black holes (BHs), assuming growth due to accretion only, to learn about the
evolution of the BH mass function from $z=3$ to 0 and from it calculate the
energy budgets of different modes of feedback. We tune the parameters of the
model by matching the derived X-ray luminosity function (XLF) with the observed
XLF of active galactic nuclei. We then calculate the amount of comoving kinetic
and bolometric feedback as a function of redshift, derive a kinetic luminosity
function and estimate the amount of kinetic feedback and $PdV$ work done by
classical double Fanaroff-Riley II (FR II) radio sources. We also derive the
radio luminosity function for FR IIs from our synthesized population and set
constraints on jet duty cycles. Around 1/6 of the jet power from FR II sources
goes into $PdV$ work done in the expanding lobes during the time the jet is on.
Anti hierarchical growth of BHs is seen in our model due to addition of an
amount of mass being accreted on to all BHs independent of the BH mass. The
contribution to the total kinetic feedback by active galaxies in a low
accretion, kinetically efficient mode is found to be the most significant at
$z<1.5$. FR II feedback is found to be a significant mode of feedback above
redshifts $z\sim 1.5$, which has not been highlighted by previous studies.


title:
A Supersymmetric Model for Dark Matter and Baryogenesis Motivated by the
  Recent CDMS Result

abstract:
  We discuss a supersymmetric model for cogenesis of dark and baryonic matter
where the dark matter (DM) has mass in the 8-10 GeV range as indicated by
several direct detection searches including most recently the CDMS experiment
with the desired cross section. The DM candidate is a real scalar filed. Two
key distinguishing features of the model are the following: (i) in contrast
with the conventional WIMP dark matter scenarios where thermal freeze-out is
responsible for the observed relic density, our model uses non-thermal
production of dark matter after reheating of the universe caused by moduli
decay at temperatures below the QCD phase transition, a feature which
alleviates the relic over-abundance problem caused by small annihilation cross
section of light DM particles; (ii) baryogenesis occurs also at similar low
temperatures from the decay of TeV scale mediator particles arising from moduli
decay. A possible test of this model is the existence of colored particles with
TeV masses accessible at the LHC.


title: A Curie-Weiss model with dissipation

abstract:
  We consider stochastic dynamics for a spin system with mean field
interaction, in which the interaction potential is subject to noisy and
dissipative stochastic evolution. We show that, in the thermodynamic limit and
at sufficiently low temperature, the magnetization of the system has a time
periodic behavior, despite of the fact that no periodic force is applied.


title: Pessimal packing shapes

abstract:
  We address the question of which convex shapes, when packed as densely as
possible under certain restrictions, fill the least space and leave the most
empty space. In each different dimension and under each different set of
restrictions, this question is expected to have a different answer or perhaps
no answer at all. As the problem of identifying global minima in most cases
appears to be beyond current reach, in this paper we focus on local minima. We
review some known results and prove these new results: in two dimensions, the
regular heptagon is a local minimum of the double-lattice packing density, and
in three dimensions, the directional derivative (in the sense of Minkowski
addition) of the double-lattice packing density at the point in the space of
shapes corresponding to the ball is in every direction positive.


title:
Driving a mechanical resonator in to coherent states via random
  measurements

abstract:
  We propose dynamical schemes to engineer coherent states of a mechanical
resonator coupled to an ancillary, superconducting flux qubit. The flux qubit,
when repeatedly projected on to its ground state drives the mechanical
resonator in to a coherent state in probabilistic, albeit heralded fashion.
Assuming no operations on the state of the mechanical resonator during the
protocol, coherent states are successfully generated only up to a certain value
of the displacement parameter. This restriction can be overcome at the cost of
a one-time operation on the initial state of the mechanical resonator. We
discuss the possibility of experimental realization of the presented schemes.


title: 3d TQFT from 6d SCFT

abstract:
  We study the six-dimensional (2,0) superconformal field theory on S^1 x S^2 x
M via compactification to five dimensions, where M is a three-manifold. Twisted
along M, the five-dimensional theory has a half of N = (2,2) supersymmetry on
S^2, the other half being broken by a superpotential. We show that in the limit
where M is infinitely large, the twisted theory reduces to a three-dimensional
topological quantum field theory which is closely related to Chern-Simons
theory for the complexified gauge group.


title: Insights into the gamma* N -> Delta transition

abstract:
  The \gamma* N -> \Delta(1232) transition is a window on hadron shape
deformation, the applicability of perturbative QCD at moderate momentum
transfers, and the influence of nonperturbative phenomena on hadronic
observables. We explain that the Ash-convention magnetic transition form factor
must fall faster than the neutron's magnetic form factor and nonzero values for
the associated quadrupole ratios reveal the impact of quark orbital angular
momentum within the nucleon and \Delta(1232); and show that these quadrupole
ratios do approach their predicted asymptotic limits, albeit slowly.


title: Fission properties of the BCPM functional

abstract:
  We explore the properties of the Barcelona Catania Paris Madrid (BCPM) energy
density functional concerning fission dynamics. Potential energy surfaces as
well as collective inertias relevant in the fission process are computed for
several nuclei where experimental data exists. Inner and outer barrier heights
as well as fission isomer excitation energies are reproduced quite well in all
the cases. The spontaneous fission half lives $t_{\textrm{\textrm{SF}}}$ are
also computed using the standard semiclassical approach and the results are
compared with the experimental data. A reasonable agreement with experiment is
found over a range of 27 orders of magnitude but the theoretical predictions
suffer from large uncertainties associated to the values of the parameters
entering the spontaneous fission half life formula. The impact that increasing
the pairing correlations strengths has in the spontaneous fission half lives is
analyzed and found to be large in all the nuclei considered. Given the
satisfactory description of the trend of fission properties with mass number we
explore the fission properties of the even-even uranium isotope chain from
$^{226}$U to $^{282}$U. Very large half lives are found when getting close to
neutron number N=184.


title: The Ramsey number of generalized loose paths in uniform Hypergrpahs

abstract:
  Let $H=(V,E)$ be an $r$-uniform hypergraph. For each $1 \leq s \leq r-1$, an
$s$-path ${\mathcal P}^{r,s}_n$ of length $n$ in $H$ is a sequence of distinct
vertices $v_1,v_2,\ldots,v_{s+n(r-s)}$ such that $\{v_{1+i(r-s)},\ldots,
v_{s+(i+1)(r-s)}\}\in E(H)$ for each $0 \leq i \leq n-1$.Recently, the Ramsey
number of $1$-paths in uniform hypergraphs has received a lot of attention. In
this paper, we consider the Ramsey number of $r/2-$paths for even $r$. Namely,
we prove the following exact result: $R({\mathcal P}^{r,r/2}_n,{\mathcal
P}^{r,r/2}_3)=R({\mathcal P}^{r,r/2}_n,{\mathcal
P}^{r,r/2}_4)=\tfrac{(n+1)r}{2}+1.$


title:
On perturbative instability of Pope-Warner solutions on Sasaki-Einstein
  manifolds

abstract:
  Given a Sasaki-Einstein manifold, M_7, there is the N=2 supersymmetric AdS_4
x M_7 Freund-Rubin solution of eleven-dimensional supergravity and the
corresponding non-supersymmetric solutions: the perturbatively stable
skew-whiffed solution, the perturbatively unstable Englert solution, and the
Pope-Warner solution, which is known to be perturbatively unstable when M_7 is
the seven-sphere or, more generally, a tri-Sasakian manifold. We show that
similar perturbative instability of the Pope-Warner solution will arise for any
Sasaki-Einstein manifold, M_7, admitting a basic, primitive, transverse
(1,1)-eigenform of the Hodge-de Rham Laplacian with the eigenvalue in the range
between 2(9-4\sqrt 3) and 2(9+4\sqrt 3). Existence of such (1,1)-forms on all
homogeneous Sasaki-Einstein manifolds can be shown explicitly using the Kahler
quotient construction or the standard harmonic expansion. The latter shows that
the instability arises from the coupling between the Pope-Warner background and
Kaluza-Klein scalar modes that at the supersymmetric point lie in a long
Z-vector supermultiplet. We also verify that the instability persists for the
orbifolds of homogeneous Sasaki-Einstein manifolds that have been discussed
recently.


title: Spiraling of approximations and spherical averages of Siegel transforms

abstract:
  We consider the question of how approximations satisfying Dirichlet's theorem
spiral around vectors in $\mathbb{R}^d$. We give pointwise almost everywhere
results (using only the Birkhoff ergodic theorem on the space of lattices). In
addition, we show that for $\textit{every}$ unimodular lattice, on average, the
directions of approximates spiral in a uniformly distributed fashion on the
$d-1$ dimensional unit sphere. For this second result, we adapt a very recent
proof of Marklof and Str\"ombergsson \cite{MS3} to show a spherical average
result for Siegel transforms on
$\operatorname{SL}_{d+1}(\mathbb{R})/\operatorname{SL}_{d+1}(\mathbb{Z})$. Our
techniques are elementary. Results like this date back to the work of
Eskin-Margulis-Mozes \cite{EMM} and Kleinbock-Margulis \cite{KM} and have
wide-ranging applications. We also explicitly construct examples in which the
directions are not uniformly distributed.


title:
The operad of wiring diagrams: formalizing a graphical language for
  databases, recursion, and plug-and-play circuits

abstract:
  Wiring diagrams, as seen in digital circuits, can be nested hierarchically
and thus have an aspect of self-similarity. We show that wiring diagrams form
the morphisms of an operad $\mcT$, capturing this self-similarity. We discuss
the algebra $\Rel$ of mathematical relations on $\mcT$, and in so doing use
wiring diagrams as a graphical language with which to structure queries on
relational databases. We give the example of circuit diagrams as a special
case. We move on to show how plug-and-play devices and also recursion can be
formulated in the operadic framework as well. Throughout we include many
examples and figures.


title: Microscopic model for the boson integer quantum Hall effect

abstract:
  In two dimensions strongly interacting bosons in a magnetic field can form an
integer quantum Hall state. This state has a bulk gap, no fractional charges or
topological order in the bulk but nevertheless has quantized Hall transport and
symmetry protected edge excitations. Here we study a simple microscopic model
for such a state in a system of two component bosons in a strong orbital
magnetic field. We show through exact diagonalization calculations that the
model supports the boson integer quantum Hall ground state in a range of
parameters.


title: Unitarity Saturation In P-P Scattering

abstract:
  The properties of soft p-p scattering amplitudes at the TeV-scale are studied
so as to identify the impact of s and t channel unitarity screenings on their
behavior at exceedingly high energies and determine the rate at which they
approach the bounds implied by unitarity saturation. I shall examine the
relevant high energy soft cross section features, as well as, the corresponding
behavior of the coupled phenomenological models aiming to reproduce this
data.\\ My conclusion is that p-p black body saturation is not attained up to
100 TeV. More over, I do not expect that saturation will be attained at
energies that can be investigated experimentally.


title:
Bio-imitaiton of Mexican migration routes to the USA with slime mould on
  3D terrains

abstract:
  Plasmodium of Physarum polycephalum is a large single cell visible by unaided
eye. It shows sophisticated behavioural traits in foraging for nutrients and
developing an optimal transport network of protoplasmic tubes spanning sources
of nutrients. When placed in an environment with distributed sources of
nutrients the cell 'computes' an optimal graph spanning the nutrients by
growing a network of protoplasmic tubes. P. polycephalum imitates development
of man-made transport networks of a country when configuration of nutrients
represents major urban areas. We employ this feature of the slime mould to
imitate mexican migration to USA. The Mexican migration to USA is the World's
largest migration system. We bio-physically imitate the migration using slime
mould P. polycephalum. In laboratory experiments with 3D Nylon terrains of USA
we imitated development of migratory routes from Mexico-USA border to ten urban
areas with high concentration of Mexican migrants. From results of laboratory
experiments we extracted topologies of migratory routes, and highlighted a role
of elevations in shaping the human movement networks.


title:
Predicted Rectification and Negative Differential Spin Seebeck Effect at
  Magnetic Interfaces

abstract:
  We study the nonequilibrium Seebeck spin transport across metal-magnetic
insulator interfaces. The conjugate-converted thermal-spin transport is
assisted by the exchange interaction at the interface, between conduction
electrons in the metal lead and localized spins in the insulating magnet lead.
We predict the rectification and negative differential spin Seebeck effect and
resolve their microscopic mechanism, as a consequence of the
strongly-fluctuated electronic density of states in the metal lead. The
rectification of spin Peltier effect is also discussed. The phenomena predicted
here are relevant for designing efficient spin/magnon diode and transistor,
which could play crucial roles in controlling energy and information in
functional devices.


title: Prospects for Indirect Detection of Dark Matter with CTA

abstract:
  We discuss the prospects for indirect detection of dark matter (DM) with the
Cherenkov Telescope Array (CTA), a future ground-based gamma-ray observatory
that will be sensitive to gamma rays in the energy range from a few tens of GeV
to 100 TeV. We consider the detectability of DM annihilation in different
astrophysical targets with a focus on the Galactic Center (GC) region. With a
deep observation of the GC, CTA will be sensitive to DM particles with mass
greater than 100 GeV and an annihilation cross section close to the thermal
relic value.


title:
Steady and self-similar solutions of non-strictly hyperbolic systems of
  conservation laws

abstract:
  We consider solutions of two-dimensional $m \times m$ systems hyperbolic
conservation laws that are constant in time and along rays starting at the
origin. The solutions are assumed to be small $L^\infty$ perturbations of a
constant state and entropy admissible, and the system is assumed to be
non-strictly hyperbolic with eigenvalues of constant multiplicity. We show that
such a solution, initially assumed bounded, must be a special function of
bounded variation, and we determine the possible configuration of waves. As a
corollary, we extend some regularity and uniqueness results for some
one-dimensional Riemann problems.


title: Generating artificial light curves: Revisited and updated

abstract:
  The production of artificial light curves with known statistical and
variability properties is of great importance in astrophysics. Consolidating
the confidence levels during cross-correlation studies, understanding the
artefacts induced by sampling irregularities, establishing detection limits for
future observatories are just some of the applications of simulated data sets.
Currently, the widely used methodology of amplitude and phase randomisation is
able to produce artificial light curves which have a given underlying power
spectral density (PSD) but which are strictly Gaussian distributed. This
restriction is a significant limitation, since the majority of the light curves
e.g. active galactic nuclei, X-ray binaries, gamma-ray bursts show strong
deviations from Gaussianity exhibiting `burst-like' events in their light
curves yielding long-tailed probability distribution functions (PDFs). In this
study we propose a simple method which is able to precisely reproduce light
curves which match both the PSD and the PDF of either an observed light curve
or a theoretical model. The PDF can be representative of either the parent
distribution or the actual distribution of the observed data, depending on the
study to be conducted for a given source. The final artificial light curves
contain all of the statistical and variability properties of the observed
source or theoretical model i.e. same PDF and PSD, respectively. Within the
framework of Reproducible Research, the code, together with the illustrative
example used in this manuscript, are both made publicly available in the form
of an interactive Mathematica notebook.

categories: astro-ph.IM astro-ph.CO astro-ph.GA astro-ph.HE astro-ph.SR


title:
Network-Centric Quantum Communications with Application to Critical
  Infrastructure Protection

abstract:
  Network-centric quantum communications (NQC) - a new, scalable instantiation
of quantum cryptography providing key management with forward security for
lightweight encryption, authentication and digital signatures in optical
networks - is briefly described. Results from a multi-node experimental
test-bed utilizing integrated photonics quantum communications components,
known as QKarDs, include: quantum identification; verifiable quantum secret
sharing; multi-party authenticated key establishment, including group keying;
and single-fiber quantum-secured communications that can be applied as a
security retrofit/upgrade to existing optical fiber installations. A
demonstration that NQC meets the challenging simultaneous latency and security
requirements of electric grid control communications, which cannot be met
without compromises using conventional cryptography, is described.


title:
Abundance-weighted phylogenetic diversity measures distinguish microbial
  community states and are robust to sampling depth

abstract:
  In microbial ecology studies, the most commonly used ways of investigating
alpha (within-sample) diversity are either to apply count-only measures such as
Simpson's index to Operational Taxonomic Unit (OTU) groupings, or to use
classical phylogenetic diversity (PD), which is not abundance-weighted.
Although alpha diversity measures that use abundance information in a
phylogenetic framework do exist, but are not widely used within the microbial
ecology community. The performance of abundance-weighted phylogenetic diversity
measures compared to classical discrete measures has not been explored, and the
behavior of these measures under rarefaction (sub-sampling) is not yet clear.
In this paper we compare the ability of various alpha diversity measures to
distinguish between different community states in the human microbiome for
three different data sets. We also present and compare a novel one-parameter
family of alpha diversity measures, BWPD_\theta, that interpolates between
classical phylogenetic diversity (PD) and an abundance-weighted extension of
PD. Additionally, we examine the sensitivity of these phylogenetic diversity
measures to sampling, via computational experiments and by deriving a closed
form solution for the expectation of phylogenetic quadratic entropy under
re-sampling. In all three of the datasets considered, an abundance-weighted
measure is the best differentiator between community states. OTU-based
measures, on the other hand, are less effective in distinguishing community
types. In addition, abundance-weighted phylogenetic diversity measures are less
sensitive to differing sampling intensity than their unweighted counterparts.
Based on these results we encourage the use of abundance-weighted phylogenetic
diversity measures, especially for cases such as microbial ecology where
species delimitation is difficult.


title:
Turbulence-Induced Relative Velocity of Dust Particles I: Identical
  Particles

abstract:
  We study the relative velocity of inertial particles suspended in turbulent
flows and discuss implications for dust particle collisions in protoplanetary
disks. We simulate a weakly compressible turbulent flow, evolving 14 particle
species with friction timescale, tau_p, covering the entire range of scales in
the flow. The particle Stokes numbers, St, measuring the ratio of tau_p to the
Kolmogorov timescale, are in the range from ~0.1 to ~800. Using simulation
results, we show that the model by Pan & Padoan (PP10) gives satisfactory
predictions for the rms relative velocity between identical particles. The
probability distribution function (PDF) of the relative velocity is found to be
highly non-Gaussian. The PDF tails are well described by a 4/3 stretched
exponential function for particles with tau_p ~ 1-2 T_L, where T_L is the
Lagrangian correlation timescale, consistent with a prediction based on PP10.
The PDF approaches Gaussian only for very large particles with tau_p >~ 54 T_L.
We split particle pairs at given distances into two types with low and high
relative speeds, referred to as continuous and caustic types, respectively, and
compute their contributions to the collision kernel. Although amplified by the
effect of clustering, the continuous contribution vanishes in the limit of
infinitesimal particle distance, where the caustic contribution dominates. The
caustic kernel per unit cross section rises rapidly as St increases toward ~1,
reaches a maximum at tau_p ~ 2 T_L, and decreases as tau_p^{-1/2} for tau_p >>
T_L.


title:
Gravitational collapse of a magnetized fermion gas with finite
  temperature

abstract:
  We examine the dynamics of a self--gravitating magnetized electron gas at
finite temperature near the collapsing singularity of a Bianchi-I spacetime.
Considering a general and appropriate and physically motivated initial
conditions, we transform Einstein--Maxwell field equations into a complete and
self--consistent dynamical system amenable for numerical work. The resulting
numerical solutions reveal the gas collapsing into both, isotropic
("point-like") and anisotropic ("cigar-like") singularities, depending on the
initial intensity of the magnetic field. We provide a thorough study of the
near collapse behavior and interplay of all relevant state and kinematic
variables: temperature, expansion scalar, shear scalar, magnetic field,
magnetization and energy density. A significant qualitative difference in the
behavior of the gas emerges in the temperature range $\hbox{T}
sim10^{4}\hbox{K}$ and $\hbox{T}\sim 10^{7}\hbox{K}$.


title: The Influence of Motion and Stress on Optical Fibers

abstract:
  We report on extensive testing carried out on the optical fibers for the
VIRUS instrument. The primary result of this work explores how 10+ years of
simulated wear on a VIRUS fiber bundle affects both transmission and focal
ratio degradation (FRD) of the optical fibers. During the accelerated lifetime
tests we continuously monitored the fibers for signs of FRD. We find that
transient FRD events were common during the portions of the tests when motion
was at telescope slew rates, but dropped to negligible levels during rates of
motion typical for science observation. Tests of fiber transmission and FRD
conducted both before and after the lifetime tests reveal that while
transmission values do not change over the 10+ years of simulated wear, a clear
increase in FRD is seen in all 18 fibers tested. This increase in FRD is likely
due to microfractures that develop over time from repeated flexure of the fiber
bundle, and stands in contrast to the transient FRD events that stem from
localized stress and subsequent modal diffusion of light within the fibers.
There was no measurable wavelength dependence on the increase in FRD over 350
nm to 600 nm. We also report on bend radius tests conducted on individual
fibers and find the 266 microns VIRUS fibers to be immune to bending-induced
FRD at bend radii of R > 10cm. Below this bend radius FRD increases slightly
with decreasing radius. Lastly, we give details of a degradation seen in the
fiber bundle currently deployed on the Mitchell Spectrograph (formally VIRUS-P)
at McDonald Observatory. The degradation is shown to be caused by a localized
shear in a select number of optical fibers that leads to an explosive form of
FRD. In a few fibers, the overall transmission loss through the instrument can
exceed 80%.


title: A Birkhoff theorem for Shape Dynamics

abstract:
  Shape Dynamics is a theory of gravity that replaces refoliation invariance
for spatial Weyl invariance. Those solutions of the Einstein equations that
have global, constant mean curvature slicings, are mirrored by solutions in
Shape Dynamics. However, there are solutions of Shape Dynamics that have no
counterpart in General relativity, just as there are solutions of GR that are
not completely foliable by global constant mean curvature slicings (such as the
Schwarzschild spacetime). It is therefore interesting to analyze directly the
equations of motion of Shape Dynamics in order to find its own solutions,
irrespective of properties of known solutions of GR. Here I perform a first
study in this direction by utilizing the equations of motion of Shape Dynamics
in a spherically symmetric, asymptotically flat ansatz to derive an analogue of
the Birkhoff theorem. There are two significant differences with respect to the
usual Birkhoff theorem in GR. The first regards the construction of the
solution: the spatial Weyl gauge freedom of shape dynamics is used to simplify
the problem, and boundary conditions are required. In fact the derivation is
simpler than the usual Birkhof theorem as no Christoffel symbols are needed.
The second, and most important difference is that the solution obtained is
uniquely the isotropic wormhole solution, in which no singularity is present,
as opposed to maximally extended Schwarzschild. This provides an explicit
example of the breaking of the duality between General relativity and Shape
Dynamics, and exhibits some of its consequences.


title: An Adaptive Descriptor Design for Object Recognition in the Wild

abstract:
  Digital images nowadays have various styles of appearance, in the aspects of
color tones, contrast, vignetting, and etc. These 'picture styles' are directly
related to the scene radiance, image pipeline of the camera, and post
processing functions. Due to the complexity and nonlinearity of these causes,
popular gradient-based image descriptors won't be invariant to different
picture styles, which will decline the performance of object recognition. Given
that images shared online or created by individual users are taken with a wide
range of devices and may be processed by various post processing functions, to
find a robust object recognition system is useful and challenging. In this
paper, we present the first study on the influence of picture styles for object
recognition, and propose an adaptive approach based on the kernel view of
gradient descriptors and multiple kernel learning, without estimating or
specifying the styles of images used in training and testing. We conduct
experiments on Domain Adaptation data set and Oxford Flower data set. The
experiments also include several variants of the flower data set by processing
the images with popular photo effects. The results demonstrate that our
proposed method improve from standard descriptors in all cases.


title:
Search for Dark Matter Subhalos in the High-Energy Gamma-ray Band with
  Fermi and the Cherenkov Telescope Array

abstract:
  We discuss the potential for the detection of dark matter and the
characterization of its particle nature via the observation of dark matter
subhalos. Specifically, we discuss the search for dark matter Galactic subhalos
in the gamma-ray band with the Large Area Telescope on-board the Fermi
gamma-ray Space Telescope, and the future generation of imaging atmospheric
Cherenkov telescopes, best represented by the planned Cherenkov Telescope
Array.


title:
Primordial Non-Gaussianity Estimation using 21 cm Tomography from the
  Epoch of Reionization

abstract:
  Measuring the small primordial nonGaussianity (PNG) predicted by cosmic
inflation theories may help diagnose them. The detectability of PNG by its
imprint on the 21cm power spectrum from the epoch of reionization is reassessed
here in terms of $f_{NL}$, the local nonlinearity parameter. We find that an
optimum, multi-frequency observation by SKA can achieve $\Delta f_{NL} \sim 3$
(comparable to recent Planck CMB limits), while a cosmic-variance-limited array
of this size like Omniscope can even detect $\Delta f_{NL} \sim 0.2$. This
substantially revises the methods and results of previous work.


title: Power spectrum of electronic heat current fluctuations

abstract:
  We analyze the fluctuations of an electronic thermal current across an
idealized molecular junction. The focus here will be on the spectral features
of the resulting heat fluctuations. By use of the Green functionmethod we
derive an explicit expression for the frequency-dependent power spectral
density of the emerging energy fluctuations. The complex expression simplifies
considerably in the limit of zero frequency, yielding the noise intensity of
the heat current. The spectral density for the electronic heat fluctuations
still depends on the frequency in the zero-temperature limit, assuming
different asymptotic behaviours in the low- and high-frequency regions. We
further address subtleties and open problems from an experimental viewpoint for
measurements of frequency-dependent power spectral densities.


title:
Conductance of partially disordered graphene: Crossover from
  temperature-dependent to field-dependent variable-range hopping

abstract:
  We report and analyze low-temperature measurements of the conductance of
partially disordered reduced graphene oxide, finding that the data follow a
simple crossover scenario. At room temperature, conductance is dominated by
two-dimensional (2D) electric field-assisted, thermally-driven (Pollak-Riess)
variable-range hopping (VRH) through highly-disordered regions. However, at
lower temperatures T, we find a smooth crossover to follow the
exp(-E_0/E)^(1/3) field-driven (Shklovskii) 2D VRH conductance behaviour when
the electric field E exceeds a specific crossover value E_C (T)_2D = (E_a
E_0^(1/3) /3)^(3/4) determined by the scale factors E_0 and E_a for the
high-field and intermediate field regimes respectively. Our crossover scenario
also accounts well for experimental data reported by other authors for
three-dimensional disordered carbon networks, suggesting wide applicability.


title: Spin Caloritronics in graphene with Mn

abstract:
  We show that graphene with Mn adatoms trapped at single vacancies feature
spin-dependent Seebeck effect, thus enabling the use of this material for spin
caloritronics. A gate potential can be used to tune its thermoelectric
properties in a way it presents either a total spin polarized current, flowing
in one given direction, or currents for both spins flowing in opposite
directions without net charge transport. Moreover, we show that the thermal
magnetoresistance can be tuned between $-100\%$ and $+100\%$ by varying agate
potential.


title: Optical "Bernoulli" forces

abstract:
  By Bernoulli's law, an increase in the relative speed of a fluid around a
body is accompanies by a decrease in the pressure. Therefore, a rotating body
in a fluid stream experiences a force perpendicular to the motion of the fluid
because of the unequal relative speed of the fluid across its surface. It is
well known that light has a constant speed irrespective of the relative motion.
Does a rotating body immersed in a stream of photons experience a
Bernoulli-like force? We show that, indeed, a rotating dielectric cylinder
experiences such a lateral force from an electromagnetic wave. In fact, the
sign of the lateral force is the same as that of the fluid-mechanical analogue
as long as the electric susceptibility is positive (\epsilon>\epsilon_{0}), but
for negative-susceptibility materials (e.g. metals) we show that the lateral
force is in the opposite direction. Because these results are derived from a
classical electromagnetic scattering problem, Mie-resonance enhancements that
occur in other scattering phenomena also enhance the lateral force.


title: Reading between the lines of four-dimensional gauge theories

abstract:
  Starting with a choice of a gauge group in four dimensions, there is often
freedom in the choice of magnetic and dyonic line operators. Different
consistent choices of these operators correspond to distinct physical theories,
with the same correlation functions of local operators in R^4. In some cases
these choices are permuted by shifting the theta-angle by 2pi. In other cases
they are labeled by new discrete theta-like parameters. Using this
understanding we gain new insight into the dynamics of four-dimensional gauge
theories and their phases. The existence of these distinct theories clarifies a
number of issues in electric/magnetic dualities of supersymmetric gauge
theories, both for the conformal N=4 theories and for the low-energy dualities
of N=1 theories.


title:
Learning Mixtures of Bernoulli Templates by Two-Round EM with
  Performance Guarantee

abstract:
  Dasgupta and Shulman showed that a two-round variant of the EM algorithm can
learn mixture of Gaussian distributions with near optimal precision with high
probability if the Gaussian distributions are well separated and if the
dimension is sufficiently high. In this paper, we generalize their theory to
learning mixture of high-dimensional Bernoulli templates. Each template is a
binary vector, and a template generates examples by randomly switching its
binary components independently with a certain probability. In computer vision
applications, a binary vector is a feature map of an image, where each binary
component indicates whether a local feature or structure is present or absent
within a certain cell of the image domain. A Bernoulli template can be
considered as a statistical model for images of objects (or parts of objects)
from the same category. We show that the two-round EM algorithm can learn
mixture of Bernoulli templates with near optimal precision with high
probability, if the Bernoulli templates are sufficiently different and if the
number of features is sufficiently high. We illustrate the theoretical results
by synthetic and real examples.


title:
MCMC for non-linear state space models using ensembles of latent
  sequences

abstract:
  Non-linear state space models are a widely-used class of models for
biological, economic, and physical processes. Fitting these models to observed
data is a difficult inference problem that has no straightforward solution. We
take a Bayesian approach to the inference of unknown parameters of a non-linear
state model; this, in turn, requires the availability of efficient Markov Chain
Monte Carlo (MCMC) sampling methods for the latent (hidden) variables and model
parameters. Using the ensemble technique of Neal (2010) and the embedded HMM
technique of Neal (2003), we introduce a new Markov Chain Monte Carlo method
for non-linear state space models. The key idea is to perform parameter updates
conditional on an enormously large ensemble of latent sequences, as opposed to
a single sequence, as with existing methods. We look at the performance of this
ensemble method when doing Bayesian inference in the Ricker model of population
dynamics. We show that for this problem, the ensemble method is vastly more
efficient than a simple Metropolis method, as well as 1.9 to 12.0 times more
efficient than a single-sequence embedded HMM method, when all methods are
tuned appropriately. We also introduce a way of speeding up the ensemble method
by performing partial backward passes to discard poor proposals at low
computational cost, resulting in a final efficiency gain of 3.4 to 20.4 times
over the single-sequence method.


title: Hidden Markov Model Identifiability via Tensors

abstract:
  The prevalence of hidden Markov models (HMMs) in various applications of
statistical signal processing and communications is a testament to the power
and flexibility of the model. In this paper, we link the identifiability
problem with tensor decomposition, in particular, the Canonical Polyadic
decomposition. Using recent results in deriving uniqueness conditions for
tensor decomposition, we are able to provide a necessary and sufficient
condition for the identification of the parameters of discrete time finite
alphabet HMMs. This result resolves a long standing open problem regarding the
derivation of a necessary and sufficient condition for uniquely identifying an
HMM. We then further extend recent preliminary work on the identification of
HMMs with multiple observers by deriving necessary and sufficient conditions
for identifiability in this setting.


title: Tuning the charge-transfer energy in hole-doped cuprates

abstract:
  Chemical substitution, combined with strain, allows the charge-transfer
energy in hole-doped cuprates to be broadly tuned. We theoretically
characterize the structural and electronic properties of the family of
compounds $R_2$CuO$_2$S$_2$, constructed by sulfur replacement of the apical
oxygens and rare earth substitutions in the parent cuprate La$_2$CuO$_4$.
Additionally, the enthalpies of formation for possible synthesis pathways are
determined.


title: Zeros of the Riemann Zeta Function

abstract:
  In this paper, we present a proof of the Riemann hypothesis. We show that
zeros of the Riemann zeta function should be on the line with the real value
1/2, in the region where the real part of complex variable is between 0 and 1.


title:
Lower bound for the rate of blow-up of singular solutions of the
  Zakharov system in $\R^3$

abstract:
  We consider the scalar Zakharov system in $\R^3$ for initial conditions
$(\psi(0), n(0), n_t(0)) \in H^{\ell+1/2} \times H^\ell \times H^{\ell-1} $,
  $0\leq\ell \leq 1$. Assuming that the solution blows up in a finite time $t^*
< \infty$, we establish a lower bound for the rate of blow-up of the
corresponding Sobolev norms in the form $$ \|\psi(t)\|_{H^{\ell+1/2}}
+\|n(t)\|_{H^{\ell}} + \|n_t(t)\|_{H^{\ell-1}} > C(t^*-t)^{-\theta_\ell} $$
with $\theta_\ell = \frac{1}{4}(1+ 2 \ell)^-$. The analysis is a reappraisal of
the local wellposedness theory of Ginibre, Tsutsumi and Velo (1997) combined
with an argument developed by Cazenave and Weissler (1990) in the context of
nonlinear Schr\"odinger equations.


title: High velocity HI is not associated with TeV supernova remnant W51C

abstract:
  The recently-detected TeV gamma-ray source HESS J1923+141 coincides with
Supernova Remnant (SNR) W51C and the star forming region W51B of the W51
complex. We construct HI absorption spectra to SNR W51C, HII regions G49.2-0.35
and G49.1-0.38 in W51B, and a nearby compact extragalactic source. Our study
detects high-velocity (HV) HI clouds (above 83 km/s) which coincide with W51B,
but finds that the clouds are behind W51B. Both W51C and G49.2-0.35 have have
similar highest-velocity absorption features at ~70 km/s. The HII region
G49.1-0.38 is behind the SNR because its HI absorption spectrum has a feature
at 83 km/s. These new results argue against previous claims that the SNR has
shocked the HV HI clouds. Therefore the TeV emission from the complex should
not be associated with the HV HI clouds. W51C has a distance of about 4.3 kpc,
smaller than the tangent point distance of 5.5 kpc in that direction, but still
in the Sagittarius spiral arm.


title: Pulsar Timing Array Analysis for Black Hole Backgrounds

abstract:
  An astrophysical population of supermassive black hole binaries is thought to
be the strongest source of gravitational waves in the frequency range covered
by Pulsar Timing Arrays (PTAs). A potential cause for concern is that the
standard cross-correlation method used in PTA data analysis assumes that the
signals are isotropically distributed and Gaussian random, while the signals
from a black hole population are likely to be anisotropic and deterministic.
Here we argue that while the conventional analysis is not optimal, it is not
hopeless either, as the standard Hellings-Downs correlation curve turns out to
hold for point sources, and the small effective number of signal samples blurs
the distinction between Gaussian and deterministic signals. Possible
improvements to the standard cross-correlation analysis that account for the
anisotropy of the signal are discussed.


title:
Observation of non-sinusoidal current-phase relation in graphene
  Josephson junctions

abstract:
  We present direct measurements of the current-phase relation for lateral
Josephson junctions with a graphene barrier, obtained by a phase-sensitive
SQUID interferometry technique. We find that the current-phase relation is
forward skewed with respect to the commonly observed sinusoidal behavior for
short junctions in the quasi-ballistic transport regime, consistent with
predictions for the behavior of Dirac fermions in a Josephson junction. The
skewness increases with critical current and decreases sharply with increasing
temperature.


title: General Type Token Distribution

abstract:
  We consider the problem of estimating the number of types in a corpus using
the number of types observed in a sample of tokens from that corpus. We derive
exact and asymptotic distributions for the number of observed types,
conditioned upon the number of tokens and the latent type distribution. We use
the asymptotic distributions to derive an estimator of the latent number of
types and we validate this estimator numerically.


title:
Vacuum Stability, Perturbativity, EWPD and Higgs-to-diphoton in Type II
  Seesaw

abstract:
  We study constraints from perturbativity and vacuum stability as well as the
EWPD in the type II seesaw model. As a result, we can put stringent limits on
the Higgs triplet couplings depending on the cut-off scale. The EWPD tightly
constrain the Higgs triplet mass splitting to be smaller than about 40 GeV.
Analyzing the Higgs-to-diphoton rate in the allowed parameter region, we show
how much it can deviate from the Standard Model prediction for specific
parameter points.


title:
Antiferromagnetic states and phase separation in doped AA-stacked
  graphene bilayers

abstract:
  We study electronic properties of AA-stacked graphene bilayers. In the
single-particle approximation such a system has one electron band and one hole
band crossing the Fermi level. If the bilayer is undoped, the Fermi surfaces of
these bands coincide. Such a band structure is unstable with respect to a set
of spontaneous symmetry violations. Specifically, strong on-site Coulomb
repulsion stabilizes antiferromagnetic order. At small doping and low
temperatures, the homogeneous phase is unstable, and experiences phase
separation into an undoped antiferromagnetic insulator and a metal. The
metallic phase can be either antiferromagnetic (commensurate or incommensurate)
or paramagnetic depending on the system parameters. We derive the phase diagram
of the system on the doping-temperature plane and find that, under certain
conditions, the transition from paramagnetic to antiferromagnetic phase may
demonstrate re-entrance. When disorder is present, phase separation could
manifest itself as a percolative insulator-metal transition driven by doping.


title:
Spontaneous and Stimulated Raman Scattering near Metal Nanostructures in
  the Ultrafast, High-Intensity regime

abstract:
  The inclusion of atomic inversion in Raman scattering can significantly alter
field dynamics in plasmonic settings. Our calculations show that large local
fields and femtosecond pulses combine to yield: (i) population inversion within
hot spots; (ii) gain saturation; and (iii) conversion efficiencies
characterized by a switch-like transition to the stimulated regime that spans
twelve orders of magnitude. While in Raman scattering atomic inversion is
usually neglected, we demonstrate that in some circumstances full accounting of
the dynamics of the Bloch vector is required.


title:
Volume term of work of critical nucleus formation in terms of chemical
  potential difference relative to equilibrium one

abstract:
  The work of formation of a critical nucleus is sometimes written as
W=n{\Delta}{\mu}+{\gamma}A. The first term W_{vol}=n{\Delta}{\mu} is called the
volume term and the second term {\gamma}A the surface term with {\gamma} being
the interfacial tension and A the area of the nucleus. Nishioka and Kusaka [J.
Chem. Phys. 96 (1992) 5370] derived W_{vol}=n{\Delta}{\mu} with
n=V_{\beta}/v_{\beta} and
{\Delta}{\mu}={\mu}_{\beta}(T,p_{\alpha})-{\mu}_{\alpha}(T,p_{\alpha}) by
rewriting W_{vol}=-(p_{\beta}-p_{\alpha})V_{\beta} by integrating the
isothermal Gibbs-Duhem relation for an incompressible {\beta} phase, where
{\alpha} and {\beta} represent the parent and nucleating phases, V_{\beta} is
the volume of the nucleus, v_{\beta}, which is constant, the molecular volume
of the {\beta} phase, {\mu}, T, and p denote the chemical potential, the
temperature, and the pressure, respectively. We note here that
{\Delta}{\mu}={\mu}_{\beta}(T,p_{\alpha})-{\mu}_{\alpha}(T,p_{\alpha}) is, in
general, not a directly measurable quantity. In this paper, we have rewritten
W_{vol}=-(p_{\beta}-p_{\alpha})V_{\beta} in terms of {\mu}_{re}-{\mu}_{eq},
where {\mu}_{re} and {\mu}_{eq} are the chemical potential of the reservoir
(equaling that of the real system, common to the {\alpha} and {\beta} phases)
and that at equilibrium. Here, the quantity {\mu}_{re}-{\mu}_{eq} is the
directly measurable supersaturation. The obtained form is similar to but
slightly different from W_{vol}=n{\Delta}{\mu}.


title:
Ionospheric dispersion compensation using a novel microwave
  de-dispersion filter

abstract:
  Free electrons in the ionosphere lead to significant group delay dispersion
for signals in the megahertz and low gigahertz range. A novel microwave filter
is presented that is capable of compensating for the non-linear ionospheric
dispersion over a 600 MHz bandwidth between 1.2-1.8 GHz. The design method is
general and is not limited to this particular frequency range but can provide
an arbitrary phase and amplitude response over any frequency range. Several of
the filters were constructed and used in an experiment to detect short radio
pulse emission from the lunar regolith.


title: On $\mathfrak{I}$-reconstruction Property

abstract:
  Reconstruction property in Banach spaces introduced and studied by Casazza
and Christensen in [1]. In this paper we introduce reconstruction property in
Banach spaces which satisfy $\mathfrak{I}$-property. A characterization of
reconstruction property in Banach spaces which satisfy $\mathfrak{I}$-property
in terms of frames in Banach spaces is obtained. Banach frames associated with
reconstruction property are discussed.


title: Coupled Spin and Pseudo-magnetic Field in Graphene Nanoribbons

abstract:
  Pseudo-magnetic field becomes an experimental reality after the observation
of zero-field Landau level-like quantization in strained graphene, but it is
not expected that the time-reversal symmetric pseudo-magnetic fields will have
any effect on the spin degree of freedom of the charge carriers. Here, we
demonstrate that spin-orbit coupling (SOC) could act as a bridge between
pseudo-magnetic field and spin. In quantum spin Hall (QSH) states, the
direction of the spin of edge states is tied to their direction of motion
because of the SOC. The pseudo-magnetic field affects the clockwise and
counter-clock-wise edge currents of the QSH states, and consequently lifts the
degenerate edge states of opposite spin orientation. Because of opposite signs
of the pseudo-magnetic field in two valleys of graphene, the one-dimensional
charge carriers at the two opposite edges have different group velocities, and
in some special cases the edge states can only propagate at one edge of the
nanoribbon and the group velocity at the other edge becomes zero.


title: Finitely generated ideal languages and synchronizing automata

abstract:
  We study representations of ideal languages by means of strongly connected
synchronizing automata. For every finitely generated ideal language L we
construct such an automaton with at most 2^n states, where n is the maximal
length of words in L. Our constructions are based on the De Bruijn graph.


title:
Photometric properties and luminosity function of nearby massive
  early-type galaxies

abstract:
  We perform photometric analyses for a bright early-type galaxy (ETG) sample
with 2949 galaxies ($M_{\rm r}<-22.5$ mag) in the redshift range of 0.05 to
0.15, drawn from the SDSS DR7 with morphological classification from Galaxy Zoo
1. We measure the Petrosian and isophotal magnitudes, as well as the
corresponding half-light radius for each galaxy. We find that for brightest
galaxies ($M_{\rm r}<-23$ mag), our Petrosian magnitudes, and isophotal
magnitudes to 25 ${\rm mag/arcsec^2}$ and 1\% of the sky brightness are on
average 0.16 mag, 0.20 mag, and 0.26 mag brighter than the SDSS Petrosian
values, respectively. In the first case the underestimations are caused by
overestimations in the sky background by the SDSS PHOTO algorithm, while the
latter two are also due to deeper photometry. Similarly, the typical half-light
radii ($r_{50}$) measured by the SDSS algorithm are smaller than our
measurements. As a result, the bright-end of the $r$-band luminosity function
is found to decline more slowly than previous works. Our measured luminosity
densities at the bright end are more than one order of magnitude higher than
those of Blanton et al. (2003), and the stellar mass densities at $M_{\ast}\sim
5\times10^{11} M_{\odot}$ and $M_{\ast}\sim 10^{12} M_{\odot}$ are a few tenths
and a factor of few higher than those of Bernardi et al. (2010). These results
may significantly alleviate the tension in the assembly of massive galaxies
between observations and predictions of the hierarchical structure formation
model.


title:
Origin of Macrospicule and Jet in Polar Corona by A Small-scale Kinked
  Flux-Tube

abstract:
  We report an observation of a small scale flux-tube that undergoes kinking
and triggers the macrospicule and a jet on November 11, 2010 in the north polar
corona. The small-scale flux-tube emerged well before the triggering of
macrospicule and as the time progresses the two opposite halves of this omega
shaped flux-tube bent transversely and approached towards each other. After
$\sim$ 2 minutes, the two approaching halves of the kinked flux-tube touch
each-other and internal reconnection as well as energy release takes place at
the adjoining location and a macrospicule was launched which goes upto a height
of 12 Mm. Plasma starts moving horizontally as well as vertically upward along
with the onset of macrospicule and thereafter converts into a large-scale jet
which goes up to $\sim$ 40 Mm in the solar atmosphere with a projected speed of
$\sim$ 95 km s$^{-1}$. We perform 2-D numerical simulation by considering the
VAL-C initial atmospheric conditions to understand the physical scenario of the
observed macrospicule and associated jet. The simulation results show that
reconnection generated velocity pulse in the lower solar atmosphere steepens
into slow shock and the cool plasma is driven behind it in form of
macrospicule. The horizontal surface waves also appeared with the shock fronts
at different heights, which most likely drove and spread the large-scale jet
associated with the macrospicule.


title:
A Note on Central Limit Theorems for Linear Spectral Statistics of Large
  Dimensional F-matrix

abstract:
  Sample covariance matrix and multivariate $F$-matrix play important roles in
multivariate statistical analysis. The central limit theorems {\sl (CLT)} of
linear spectral statistics associated with these matrices were established in
Bai and Silverstein (2004) and Zheng (2012) which received considerable
attentions and have been applied to solve many large dimensional statistical
problems. However, the sample covariance matrices used in these papers are not
centralized and there exist some questions about CLT's defined by the
centralized sample covariance matrices. In this note, we shall provide some
short complements on the CLT's in Bai and Silverstein (2004) and Zheng (2012),
and show that the results in these two papers remain valid for the centralized
sample covariance matrices, provided that the ratios of dimension $p$ to sample
sizes $(n,n_1,n_2)$ are redefined as $p/(n-1)$ and $p/(n_i-1)$, $i=1,2$,
respectively.


title: Second order transport from anomalies

abstract:
  We study parity odd transport at second order in derivative expansion for a
non-conformal charged fluid. We see that there are 27 parity odd transport
coefficients, of which 12 are non-vanishing in equilibrium. We use the
equilibrium partition function method to express 7 of these in terms of the
anomaly, shear viscosity, charge diffusivity and thermodynamic functions. The
remaining 5 are constrained by 3 relations which also involve the anomaly. We
derive Kubo formulae for 2 of the transport coefficients and show these agree
with that derived from the equilibrium partition function.


title: Surface pencil with a common line of curvature in Minkowski 3-space

abstract:
  In this paper, we analyze the problem of constructing a surface pencil from a
given spacelike (timelike) line of curvature. By using the Frenet frame of the
given curve in Minkowski 3-space, we express the surface pencil as a linear
combination of this frame and derive the necessary and sufficient conditions
for the coefficients to satisfy the line of curvature requirement. To
illustrate the method some examples showing members of the surface pencil with
their line of curvature are given.


title:
From Stochastic Integration wrt Fractional Brownian Motion to Stochastic
  Integration wrt Multifractional Brownian Motion

abstract:
  Stochastic integration w.r.t. fractional Brownian motion (fBm) has raised
strong interest in recent years, motivated in particular by applications in
finance and Internet traffic modelling. Since fBm is not a semi-martingale,
stochastic integration requires specific developments. Multifractional Brownian
motion (mBm) is a Gaussian process that generalizes fBm by letting the local
H\"older exponent vary in time. This is useful in various areas, including
financial modelling and biomedicine. In this work we start from the fact,
established in \cite[Thm 2.1.(i)]{fBm_to_mBm_HerbinLebovitsVehel}, that an mBm
may be approximated, in law, by a sequence of "tangent" fBms. We used this
result to show how one can define a stochastic integral w.r.t. mBm from the
stochastic integral w.r.t. fBm, defined in \cite{Ben1}, in the White Noise
Theory sense.


title: Preordered forests, packed words and contraction algebras

abstract:
  We introduce the notions of preordered and heap-preordered forests,
generalizing the construction of ordered and heap-ordered forests. We prove
that the algebras of preordered and heap-preordered forests are Hopf for the
cut coproduct, and we construct a Hopf morphism to the Hopf algebra of packed
words. Moreover, we define another coproduct on the preordered forests given by
the contraction of edges. Finally, we give a combinatorial description of
morphims defined on Hopf algebras of forests with values in the Hopf algebras
of shuffes or quasi-shuffles.


title: Equivalences between blocks of p-local Mackey algebras

abstract:
  Let $G$ be a finite group and $(K,\mathcal{O},k)$ be a $p$-modular system.
Let $R=\mathcal{O}$ or $k$. There is a bijection between the blocks of the
group algebra and the blocks of the so-called $p$-local Mackey algebra
$\mu_{R}^{1}(G)$. Let $b$ be a block of $RG$ with abelian defect group $D$. Let
$b'$ be its Brauer correspondant in $N_{G}(D)$. It is conjectured by Brou\'e
that the blocks $RGb$ and $RN_{G}(D)b'$ are derived equivalent. Here we look at
equivalences between the corresponding blocks of $p$-local Mackey algebras. We
prove that an analogue of the Brou\'e's conjecture is true for the $p$-local
Mackey algebras in the following cases: for the principal blocks of
$p$-nilpotent groups and for blocks with defect $1$. We also point out the
probable importance of \emph{splendid} equivalences for the Mackey algebras.


title:
Gepner point and strong Bogomolov-Gieseker inequality for quintic
  3-folds

abstract:
  We propose a conjectural stronger version of Bogomolov-Gieseker inequality
for stable sheaves on quintic 3-folds. Our conjecture is derived from an
attempt to construct a Bridgeland stability condition on graded matrix
factorizations, which should correspond to the Gepner point via mirror symmetry
and Orlov equivalence. We prove our conjecture in the rank two case.


title: Jet Production Studies at Colliders

abstract:
  An overview of jet production, measurement techniques, and recent physics
results from colliders is presented. Analyses utilizing jets and boson plus
jets final states are included and implications of the data are discussed. The
results presented here are a snapshot of those available at the time of the PIC
2012 conference in September 2012.


title:
Magnetically Confined Interstellar Hot Plasma in the Nuclear Bulge of
  our Galaxy

abstract:
  The origin of the Galactic center diffuse X-ray emission (GCDX) is still
under intense investigation. In particular, the interpretation of the hot (kT ~
7 keV) component of the GCDX, characterised by the strong Fe 6.7 keV line
emission, has been contentious. If the hot component originates from a truly
diffuse interstellar plasma, not a collection of unresolved point sources, such
plasma cannot be gravitationally bound, and its regeneration would require a
huge amount of energy. Here we show that the spatial distribution of the GCDX
does NOT correlate with the number density distribution of an old stellar
population traced by near-infrared light, strongly suggesting a significant
contribution of the diffuse interstellar plasma. Contributions of the old
stellar population to the GCDX are implied to be about 50 % and 20 % in the
Nuclear stellar disk and Nuclear star cluster, respectively. For the Nuclear
stellar disk, a scale height of 0.32 +- 0.02 deg is obtained for the first time
from the stellar number density profiles. We also show the results of the
extended near-infrared polarimetric observations in the central 3 deg * 2 deg
region of our Galaxy, and confirm that the GCDX region is permeated by a large
scale, toroidal magnetic field as previously claimed. Together with observed
magnetic field strengths close to energy equipartition, the hot plasma could be
magnetically confined, reducing the amount of energy required to sustain it.


title: The existence of small prime gaps in subsets of the integers

abstract:
  We consider the problem of finding small prime gaps in various sets of
integers $\mathcal{C}$. Following the work of Goldston-Pintz-Yildirim, we will
consider collections of natural numbers that are well-controlled in arithmetic
progressions. Letting $q_n$ denote the $n$-th prime in $\mathcal{C}$, we will
establish that for any small constant $\epsilon>0$, the set $\left\{q_n|
q_{n+1}-q_n \leq \epsilon \log n \right\}$ constitutes a positive proportion of
all prime numbers. Using the techniques developed by Maynard and Tao we will
also demonstrate that $\mathcal{C}$ has bounded prime gaps. Specific examples,
such as the case where $\mathcal{C}$ is an arithmetic progression have already
been studied and so the purpose of this paper is to present results for general
classes of sets.


title:
Comparison of ancilla preparation and measurement procedures for the
  Steane [[7,1,3]] code on a model ion trap quantum computer

abstract:
  We schedule the Steane [[7,1,3]] error correction on a model ion trap
architecture with ballistic transport. We compare the level one error rates for
syndrome extraction using the Shor method of ancilla prepared in verified cat
states to the DiVincenzo-Aliferis method without verification. The study
examines how the quantum error correction circuit latency and error vary with
the number of available ancilla and the choice of protocol for ancilla
preparation and measurement. We find that with few exceptions the
DiVincenzo-Aliferis method without cat state verification outperforms the
standard Shor method. We also find that additional ancilla always reduces the
latency but does not significantly change the error due to the high memory
fidelity.


title: Detection of galaxy assembly bias

abstract:
  Assembly bias describes the finding that the clustering of dark matter haloes
depends on halo formation time at fixed halo mass. In this paper, we analyse
the influence of assembly bias on galaxy clustering using both semi-analytical
models (SAMs) and observational data. At fixed stellar mass, SAMs predict that
the clustering of {\it central} galaxies depends on the specific star formation
rate (sSFR), with more passive galaxies having a higher clustering amplitude.
We find similar trends using SDSS group catalogues, and verify that these are
not affected by possible biases due to the group finding algorithm. Low mass
central galaxies reside in narrow bins of halo mass, so the observed trends of
higher clustering amplitude for galaxies with lower sSFR is not driven by
variations of the parent halo mass. We argue that the clustering dependence on
sSFR represent a direct detection of assembly bias. In addition, contrary to
what expected based on clustering of dark matter haloes, we find that low-mass
central galaxies in SAMs with larger host halo mass have a {\it lower}
clustering amplitude than their counter-parts residing in lower mass haloes.
This results from the fact that, at fixed stellar mass, assembly bias has a
stronger influence on clustering than the dependence on the parent halo mass.


title:
Magnetic and electric properties of CaMn7O12 based multiferroic
  compounds: effect of electron doping

abstract:
  The mixed-valent multiferroic compound CaMn7O12 is studied for its magnetic
and electric properties. The compound undergoes magnetic ordering below 90 K
with a helimagnetic structure followed by a low temperature magnetic anomaly
observed around 43 K. The present study shows that the magnetic anomaly at 43 K
is associated with thermal hysteresis indicating first order nature of the
transition. The compound also shows field-cooled magnetic memory and relaxation
below 43 K, although no zero-field-cooled memory is present. Clear magnetic
hysteresis loop is present in the magnetization versus field measurements
signifying the presence of some ferromagnetic clusters in the system. We doped
trivalent La at the cite of divalent Ca expecting to enhance the fraction of
Mn$^{3+}$ ions. The La doped samples show reduced magnetization, although the
temperatures associated with the magnetic anomalies remain almost unaltered.
Interestingly, the spontaneous electrical polarization below 90 K increases
drastically on La substitution. We propose that the ground state of the pure as
well as the La doped compositions contain isolated superparamagnetic like
clusters, which can give rise to metastability in the form of field-cooled
memory and relaxation. The ground state is not certainly spin glass type as it
is evident from the absence of zero-field-cooled memory and frequency shift in
the ac suceptibility measurements.


title:
Numerical Study on Spontaneous Symmetry Breaking in a XY Quantum
  Antiferromagnet on a Finite Triangular Lattice

abstract:
  Motivated by recent experiments that require more complicated macroscopic
wave functions in the condensed matters, we make numerical study on a XY
quantum antiferromagnet on a finite triangular lattice using the variational
Monte Carlo method and the stochastic state selection method. One of our
purpose is a numerical confirmation on dominance of a Nambu-Goldstone boson in
low energy excitation. For another purpose, we calculate energy, an expectation
value of a symmetry breaking operator and structure functions of spin by fixing
a quantum number of the symmetry. These calculations are made for states that
become degenerate in an infinitely large lattice. By numerical calculations we
confirm existence of a Nambu-Goldstone boson, and find dependence of a square
of the quantum number for the above quantities. Using these results we can
discuss on complicated macroscopic wave functions in quantum spin systems.


title: Spectral computations for birth and death chains

abstract:
  We consider the spectrum of birth and death chains on a $n$-path. An
iterative scheme is proposed to compute any eigenvalue with exponential
convergence rate independent of $n$. This allows one to determine the whole
spectrum in order $n^2$ elementary operations. Using the same idea, we also
provide a lower bound on the spectral gap, which is of the correct order on
some classes of examples.


title: Imaging magnetoelectric subbands in ballistic constrictions

abstract:
  We perform scanning gate experiments on ballistic constrictions in the
presence of small perpendicular magnetic fields. The constrictions form the
entrance and exit of a circular gate-defined ballistic stadium. Close to
constrictions we observe sets of regular fringes creating a checker board
pattern. Inside the stadium conductance fluctuations governed by chaotic
dynamics of electrons are visible. The checker board pattern allows us to
determine the number of transmitted modes in the constrictions forming between
the tip-induced potential and gate-defined geometry. Spatial investigation of
the fringe pattern in a perpendicular magnetic field shows a transition from
electrostatic to magnetic depopulation of magnetoelectric subbands. Classical
and quantum simulations agree well with different aspects of our observations.


title:
Model Selection for High-Dimensional Regression under the Generalized
  Irrepresentability Condition

abstract:
  In the high-dimensional regression model a response variable is linearly
related to $p$ covariates, but the sample size $n$ is smaller than $p$. We
assume that only a small subset of covariates is `active' (i.e., the
corresponding coefficients are non-zero), and consider the model-selection
problem of identifying the active covariates. A popular approach is to estimate
the regression coefficients through the Lasso ($\ell_1$-regularized least
squares). This is known to correctly identify the active set only if the
irrelevant covariates are roughly orthogonal to the relevant ones, as
quantified through the so called `irrepresentability' condition. In this paper
we study the `Gauss-Lasso' selector, a simple two-stage method that first
solves the Lasso, and then performs ordinary least squares restricted to the
Lasso active set. We formulate `generalized irrepresentability condition'
(GIC), an assumption that is substantially weaker than irrepresentability. We
prove that, under GIC, the Gauss-Lasso correctly recovers the active set.

categories: math.ST cs.IT cs.LG math.IT stat.ME stat.ML stat.TH


title:
A Markovian Model for Assessing the Consistency of Vehicular Storage
  Systems

abstract:
  In this paper, we evaluate the suitability of the vehicular devices for
supporting data storage and distribution applications. Vehicular storage
systems have recently emerged as means for making the information related to
the vehicular environment available to vehicular users. Information could
either be collected by sensors mounted onboard vehicles or coming from the
surrounding environment. Modeling a vehicular data storage and distribution
system requires the introduction of a number of parameters, such as the vehicle
concentration and transmission range, the value of which may determine the
suitability or unsuitability of the vehicular environment for establishing a
communication infrastructure with the desired quality. In this paper we show
how to solve this problem by resorting to a Markovian model and some results
achieved through its application.