title:
A combined finite volume--nonconforming finite element scheme for
  compressible two phase flow in porous media

abstract:
  We propose and analyze a combined finite volume--nonconforming finite element
scheme on general meshes to simulate the two compressible phase flow in porous
media. The diffusion term, which can be anisotropic and heterogeneous, is
discretized by piecewise linear nonconforming triangular finite elements. The
other terms are discretized by means of a cell-centered finite volume scheme on
a dual mesh, where the dual volumes are constructed around the sides of the
original mesh. The relative permeability of each phase is decentred according
the sign of the velocity at the dual interface. This technique also ensures the
validity of the discrete maximum principle for the saturation under a non
restrictive shape regularity of the space mesh and the positiveness of all
transmissibilities. Next, a priori estimates on the pressures and a function of
the saturation that denote capillary terms are established. These stabilities
results lead to some compactness arguments based on the use of the Kolmogorov
compactness theorem, and allow us to derive the convergence of a subsequence of
the sequence of approximate solutions to a weak solution of the continuous
equations, provided the mesh size tends to zero. The proof is given for the
complete system when the density of the each phase depends on the own pressure.


title:
Talagrand's inequality for Interacting Particle Systems satisfying a
  log-Sobolev inequality

abstract:
  Talagrand's inequality for independent Bernoulli random variables is extended
to many interacting particle systems (IPS). The main assumption is that the IPS
satisfies a log-Sobolev inequality. In this context it is also shown that a
slightly stronger version of Talagrand's inequality is equivalent to a
log-Sobolev inequality.
  Additionally we also look at a common application, the relation between the
probability of increasing events and the influences on that event by changing a
single spin.


title:
Achieving interoperability between the CARARE schema for monuments and
  sites and the Europeana Data Model

abstract:
  Mapping between different data models in a data aggregation context always
presents significant interoperability challenges. In this paper, we describe
the challenges faced and solutions developed when mapping the CARARE schema
designed for archaeological and architectural monuments and sites to the
Europeana Data Model (EDM), a model based on Linked Data principles, for the
purpose of integrating more than two million metadata records from national
monument collections and databases across Europe into the Europeana digital
library.


title:
Fractional Brownian Motion with Variable Hurst Parameter: Definition and
  Properties

abstract:
  A class of Gaussian processes generalizing the usual fractional Brownian
motion for Hurst indices in (1/2,1) and multifractal Brownian motion introduced
in Ralchenko and Shevchenko (Theory Probab Math Stat 80, 2010) and Boufoussi et
al. (Bernoulli 16(4), 2010) is presented. Any measurable function assuming
values in this interval can now be chosen as a variable Hurst parameter. These
processes allow for modeling of phenomena where the regularity properties can
change with time either continuously or through jumps, such as in the
volatility of a stock or in Internet traffic. Some properties of the sample
paths of the new process class, including different types of continuity and
long-range dependence, are discussed. It is found that the regularity
properties of the Hurst function chosen directly correspond to the regularity
properties of the sample paths of the processes. The long-range dependence
property of fractional Brownian motion is preserved in the larger process
class. As an application, Fokker-Planck-type equations for a time-changed
fractional Brownian motion with variable Hurst parameter are found.


title: Hardy space on the polydisk and scattering in layered media

abstract:
  Hardy space on the polydisk provides the setting for a global description of
scattering in piecewise-constant layered media, giving a simple qualitative
interpretation for the nonlinear dependence of the Green's function on
reflection coefficients and layer depths. Using explicit formulas for
amplitudes, we prove that the power spectrum of the Green's function is
approximately constant. In addition we exploit a connection to Jacobi
polynomials to derive formulas for computing reflection coefficients from
partial amplitude data. Unlike most approaches to layered media, which
variously involve scaling limits, approximations or iterative methods, the
formulas and methods in the present paper are exact and direct.


title: Hanson-Wright inequality and sub-gaussian concentration

abstract:
  In this expository note, we give a modern proof of Hanson-Wright inequality
for quadratic forms in sub-gaussian random variables. We deduce a useful
concentration inequality for sub-gaussian random vectors. Two examples are
given to illustrate these results: a concentration of distances between random
vectors and subspaces, and a bound on the norms of products of random and
deterministic matrices.


title: From minimal embeddings to minimal diffusions

abstract:
  There is a natural connection between the class of diffusions, and a certain
class of solutions to the Skorokhod Embedding Problem (SEP). We show that the
important concept of minimality in the SEP leads to the new and useful concept
of a minimal diffusion. Minimality is closely related to the martingale
property. A diffusion is minimal if it minimises the expected local time at
every point among all diffusions with a given distribution at an exponential
time. Our approach makes explicit the connection between the boundary
behaviour, the martingale property and the local time characteristics of
time-homogeneous diffusions.


title: Higher mass bottomonia

abstract:
  We show the results of a quark model calculation of the bottomonium spectrum
with self energy corrections due to the coupling to the meson-meson continuum.
The bare masses used in the calculation are computed within the relativized
quark model by Godfrey and Isgur. We also give results for the open-bottom
strong decay amplitudes of higher bottomonia in a 3P0 model.


title: Buried and accessible surface area control intrinsic protein flexibility

abstract:
  Proteins experience a wide variety of conformational dynamics that can be
crucial for facilitating their diverse functions. How is the intrinsic
flexibility required for these motions encoded in their three-dimensional
structures? Here, the overall flexibility of a protein is demonstrated to be
tightly coupled to the total amount of surface area buried within its fold. A
simple proxy for this, the relative solvent accessible surface area (Arel),
therefore shows excellent agreement with independent measures of global protein
flexibility derived from various experimental and computational methods.
Application of Arel on a large scale demonstrates its utility by revealing
unique sequence and structural properties associated with intrinsic
flexibility. In particular, flexibility as measured by Arel shows little
correspondence with intrinsic disorder, but instead tends to be associated with
multiple domains and increased {\alpha}- helical structure. Furthermore, the
apparent flexibility of monomeric proteins is found to be useful for
identifying quaternary structure errors in published crystal structures. There
is also a strong tendency for the crystal structures of more flexible proteins
to be solved to lower resolutions. Finally, local solvent accessibility is
shown to be a primary determinant of local residue flexibility. Overall this
work provides both fundamental mechanistic insight into the origin of protein
flexibility and a simple, practical method for predicting flexibility from
protein structures.


title: Categorical Realizations of Quivers

abstract:
  We introduce and study categorical realizations of quivers. This construction
generalizes comma categories and includes representations of quivers on
categories, twisted representations of quivers and bilinear pairings as special
cases. We prove a Krull-Schmidt Theorem in this general context, which results
in a Krull-Schmidt Theorem for the special cases just mentioned. We also show
that cancellation holds under milder assumptions. Using similar ideas we prove
a version of Fitting's Lemma for natural transformations between functors.


title:
Cosmological backreaction and the future evolution of an accelerating
  universe

abstract:
  We investigate the effect of backreaction due to inhomogeneities on the
evolution of the present universe within the Buchert framework. Our analysis
shows how backreaction from inhomogeneities in the presence of the cosmic event
horizon causes the current acceleration of the Universe to slow down in the
future and even lead in certain cases to the emergence of a future decelerating
epoch.


title:
Perfect Output Feedback in the Two-User Decentralized Interference
  Channel

abstract:
  In this paper, the $\eta$-Nash equilibrium ($\eta$-NE) region of the two-user
Gaussian interference channel (IC) with perfect output feedback is approximated
to within $1$ bit/s/Hz and $\eta$ arbitrarily close to $1$ bit/s/Hz. The
relevance of the $\eta$-NE region is that it provides the set of rate-pairs
that are achievable and stable in the IC when both transmitter-receiver pairs
autonomously tune their own transmit-receive configurations seeking an
$\eta$-optimal individual transmission rate. Therefore, any rate tuple outside
the $\eta$-NE region is not stable as there always exists one link able to
increase by at least $\eta$ bits/s/Hz its own transmission rate by updating its
own transmit-receive configuration. The main insights that arise from this work
are: $(i)$ The $\eta$-NE region achieved with feedback is larger than or equal
to the $\eta$-NE region without feedback. More importantly, for each rate pair
achievable at an $\eta$-NE without feedback, there exists at least one rate
pair achievable at an $\eta$-NE with feedback that is weakly Pareto superior.
$(ii)$ There always exists an $\eta$-NE transmit-receive configuration that
achieves a rate pair that is at most $1$ bit/s/Hz per user away from the outer
bound of the capacity region.


title: Absolutely Maximally Entangled Qudit Graph States

abstract:
  Absolutely maximally entangled (AME) states are multipartite entangled states
that are maximally entangled for any possible bipartition. In this paper, we
study the description of AME states within the graph state formalism. The
graphical representation provides an intuitive framework to visualize the
entanglement in graph states, which makes them a natural candidate to describe
AME states. We show two different methods of determining bipartite entanglement
in graph states and use them to define various AME graph states. We further
show that AME graph states exist for all number of parties, and that any AME
graph states shared between an even number of parties can be used to describe
quantum secret sharing schemes with a threshold or ramp access structure
directly within the graph states formalism.


title: Scaling properties of the pairing problem in the strong coupling limit

abstract:
  We study the excited states of the pairing Hamiltonian providing an expansion
for their energy in the strong coupling limit. To assess the role of the
pairing interaction we apply the formalism to the case of a heavy atomic
nucleus. We show that only a few statistical moments of the level distribution
are sufficient to yield an accurate estimate of the energy for not too small
values of the coupling $G$ and we give the analytic expressions of the first
four terms of the series. Further, we discuss the convergence radius $G_{\rm
sing}$ of the expansion showing that it strongly depends upon the details of
the level distribution. Furthermore $G_{\rm sing}$ is not related to the
critical values of the coupling $G_{\rm crit}$, which characterize the physics
of the pairing Hamiltonian, since it can exist even in the absence of these
critical points.


title:
Adaptive change of basis in entropy-based moment closures for linear
  kinetic equations

abstract:
  Entropy-based (M_N) moment closures for kinetic equations are defined by a
constrained optimization problem that must be solved at every point in a
space-time mesh, making it important to solve these optimization problems
accurately and efficiently. We present a complete and practical numerical
algorithm for solving the dual problem in one-dimensional, slab geometries. The
closure is only well-defined on the set of moments that are realizable from a
positive underlying distribution, and as the boundary of the realizable set is
approached, the dual problem becomes increasingly difficult to solve due to
ill-conditioning of the Hessian matrix. To improve the condition number of the
Hessian, we advocate the use of a change of polynomial basis, defined using a
Cholesky factorization of the Hessian, that permits solution of problems nearer
to the boundary of the realizable set. We also advocate a fixed quadrature
scheme, rather than adaptive quadrature, since the latter introduces
unnecessary expense and changes the computationally realizable set as the
quadrature changes. For very ill-conditioned problems, we use regularization to
make the optimization algorithm robust. We design a manufactured solution and
demonstrate that the adaptive-basis optimization algorithm reduces the need for
regularization. This is important since we also show that regularization slows,
and even stalls, convergence of the numerical simulation when refining the
space-time mesh. We also simulate two well-known benchmark problems. There we
find that our adaptive-basis, fixed-quadrature algorithm uses less
regularization than alternatives, although differences in the resulting
numerical simulations are more sensitive to the regularization strategy than to
the choice of basis.


title: A New Graphical Password Scheme Resistant to Shoulder-Surfing

abstract:
  Shoulder-surfing is a known risk where an attacker can capture a password by
direct observation or by recording the authentication session. Due to the
visual interface, this problem has become exacerbated in graphical passwords.
There have been some graphical schemes resistant or immune to shoulder-surfing,
but they have significant usability drawbacks, usually in the time and effort
to log in. In this paper, we propose and evaluate a new shoulder-surfing
resistant scheme which has a desirable usability for PDAs. Our inspiration
comes from the drawing input method in DAS and the association mnemonics in
Story for sequence retrieval. The new scheme requires users to draw a curve
across their password images orderly rather than click directly on them. The
drawing input trick along with the complementary measures, such as erasing the
drawing trace, displaying degraded images, and starting and ending with
randomly designated images provide a good resistance to shouldersurfing. A
preliminary user study showed that users were able to enter their passwords
accurately and to remember them over time.


title: Screw symmetry in columnar crystals

abstract:
  We show that the optimal packing of hard spheres in an infinitely long
cylinder yields structures characterised by a screw symmetry. Each packing can
be assembled by stacking a basic unit cell ad infinitum along the length of the
cylinder with each subsequent unit cell rotated by the same twist angle with
respect to the previous one. In this paper we quantitatively describe the
nature of this screw operation for all such packings in the range 1 <= D/d <=
2.715 and also briefly discuss their helicity.


title:
A three-dimensional atomistic kinetic Monte Carlo study of dynamic
  solute-interface interaction

abstract:
  A three-dimensional atomistic Kinetic Monte Carlo model was developed and
used to study the interaction between mobile solutes and a migrating interface.
While the model was developed with a simplified energetic and topological
description, it was also constructed to capture, in the absence of solute, the
Burke-Turnbull model for interface migration and, in the presence of solutes,
solute segregation to different types of interface sites. After parameterizing
the model, simulations were performed to study the relationship between average
interface velocity and imposed driving pressure for varying solute
concentration and solute diffusivity. While the effect of solute concentration
on solute drag pressure was found to be consistent with classical solute drag
models, the effect of solute diffusivity was found to give a response not
captured by either continuum or previously reported two-dimensional atomistic
models. The dependence of maximum drag pressure on solute diffusivity was
observed and attributed to the coupling between the structure of a migrating
interface and the ability for solute to remain segregated to the interface.


title: An audio CAPTCHA to distinguish humans from computers

abstract:
  CAPTCHAs are employed as a security measure to differentiate human users from
bots. A new sound-based CAPTCHA is proposed in this paper, which exploits the
gaps between human voice and synthetic voice rather than relays on the auditory
perception of human. The user is required to read out a given sentence, which
is selected randomly from a specified book. The generated audio file will be
analyzed automatically to judge whether the user is a human or not. In this
paper, the design of the new CAPTCHA, the analysis of the audio files, and the
choice of the audio frame window function are described in detail. And also,
some experiments are conducted to fix the critical threshold and the
coefficients of three indicators to ensure the security. The proposed audio
CAPTCHA is proved accessible to users. The user study has shown that the human
success rate reaches approximately 97% and the pass rate of attack software
using Microsoft SDK 5.1 is only 4%. The experiments also indicated that it
could be solved by most human users in less than 14 seconds and the average
time is only 7.8 seconds.


title:
A multi-dimensional Szemer\'edi theorem for the primes via a
  correspondence principle

abstract:
  We establish a version of the Furstenberg-Katznelson multi-dimensional
Szemer\'edi in the primes ${\mathcal P} := \{2,3,5,\ldots\}$, which roughly
speaking asserts that any dense subset of ${\mathcal P}^d$ contains
constellations of any given shape. Our arguments are based on a weighted
version of the Furstenberg correspondence principle, relative to a weight which
obeys an infinite number of pseudorandomness (or "linear forms") conditions,
combined with the main results of a series of papers by Green and the authors
which establish such an infinite number of pseudorandomness conditions for a
weight associated with the primes. The same result, by a rather different
method, has been simultaneously established by Cook, Magyar, and Titichetrakun.


title:
Delocalization of eigenvectors of random matrices with independent
  entries

abstract:
  We prove that an n by n random matrix G with independent entries is
completely delocalized. Suppose the entries of G have zero means, variances
uniformly bounded below, and a uniform tail decay of exponential type. Then
with high probability all unit eigenvectors of G have all coordinates of
magnitude O(n^{-1/2}), modulo logarithmic corrections. This comes a consequence
of a new, geometric, approach to delocalization for random matrices.


title: Cosmological solutions for a two-branes system in a vacuum bulk

abstract:
  We study the cosmology for a two branes model in a space-time of five
dimensions where the extra coordinate is compactified on an orbifold. The
hidden brane is filled with a real scalar field endowed with a quadratic
potential that behaves as primordial dark matter field. This case is analyzed
when the radion effects are negligible in comparison with the density energy;
all possible solutions are found by means of a dynamical system approach.


title: Calculating the Habitable Zone of Binary Star Systems I: S-Type Binaries

abstract:
  We have developed a comprehensive methodology for calculating the boundaries
of the habitable zone (HZ) of planet-hosting S-type binary star systems. Our
approach is general and takes into account the contribution of both stars to
the location and extent of the Binary HZ with different stellar spectral types.
We have studied how the binary eccentricity and stellar energy distribution
affect the extent of the habitable zone. Results indicate that in binaries
where the combination of mass-ratio and orbital eccentricity allows planet
formation around a star of the system to proceed successfully, the effect of a
less luminous secondary on the location of the primary's habitable zone is
generally negligible. However, when the secondary is more luminous, it can
influence the extent of the HZ. We present the details of the derivations of
our methodology and discuss its application to the Binary HZ around the primary
and secondary main sequence stars of an FF, MM, and FM binary, as well as two
known planet-hosting binaries alpha Cen AB and HD 196886.


title:
Calculating the Habitable Zone of Binary Star Systems II: P-Type
  Binaries

abstract:
  We have developed a comprehensive methodology for calculating the
circumbinary HZ in planet-hosting P-type binary star systems. We present a
general formalism for determining the contribution of each star of the binary
to the total flux received at the top of the atmosphere of an Earth-like
planet, and use the Sun's HZ to calculate the locations of the inner and outer
boundaries of the HZ around a binary star system. We apply our calculations to
the Kepler's currently known circumbinary planetary system and show the
combined stellar flux that determines the boundaries of their HZs. We also show
that the HZ in P-type systems is dynamic and depending on the luminosity of the
binary stars, their spectral types, and the binary eccentricity, its boundaries
vary as the stars of the binary undergo their orbital motion. We present the
details of our calculations and discuss the implications of the results.


title:
Electrical conductivity of multi-walled carbon nanotubes-SU8 epoxy
  composites

abstract:
  We have characterized the electrical conductivity of the composite which
consists of multi-walled carbon nanotubes dispersed in SU8 epoxy resin.
Depending on the processing conditions of the epoxy (ranging from
non-polymerized to cross-linked) we obtained tunneling and percolating-like
regimes of the electrical conductivity of the composites. We interpret the
observed qualitative change of the conductivity behavior in terms of reduced
separation between the nanotubes induced by polymerization of the epoxy matrix.


title: Compaction of cereal grain

abstract:
  We report on simple shaking experiments to measure the compaction of a column
of Firth oat grain. Such grains are elongated anisotropic particles with a
bimodal polydispersity. In these experiments, the particle configurations start
from an initially disordered, low-packing-fraction state and under vertical
shaking evolve to a dense state with evidence of nematic-like structure at the
surface of the confining tube. This is accompanied by an increase in the
packing fraction of the grain.


title: Resolving structural variability in network models and the brain

abstract:
  Large-scale white matter pathways crisscrossing the cortex create a complex
pattern of connectivity that underlies human cognitive function. Generative
mechanisms for this architecture have been difficult to identify in part
because little is known about mechanistic drivers of structured networks. Here
we contrast network properties derived from diffusion spectrum imaging data of
the human brain with 13 synthetic network models chosen to probe the roles of
physical network embedding and temporal network growth. We characterize both
the empirical and synthetic networks using familiar diagnostics presented in
statistical form, as scatter plots and distributions, to reveal the full range
of variability of each measure across scales in the network. We focus on the
degree distribution, degree assortativity, hierarchy, topological Rentian
scaling, and topological fractal scaling---in addition to several summary
statistics, including the mean clustering coefficient, shortest path length,
and network diameter. The models are investigated in a progressive, branching
sequence, aimed at capturing different elements thought to be important in the
brain, and range from simple random and regular networks, to models that
incorporate specific growth rules and constraints. We find that synthetic
models that constrain the network nodes to be embedded in anatomical brain
regions tend to produce distributions that are similar to those extracted from
the brain. We also find that network models hardcoded to display one network
property do not in general also display a second, suggesting that multiple
neurobiological mechanisms might be at play in the development of human brain
network architecture. Together, the network models that we develop and employ
provide a potentially useful starting point for the statistical inference of
brain network structure from neuroimaging data.


title: Lepton Universality in Kaon Decays

abstract:
  In the Standard Model extended by sterile neutrinos, modified W-l-nu
couplings arise, which are able to induce a tree-level enhancement to lepton
flavour universality violation in kaon decays. The additional mixing between
the active neutrinos and the sterile ones can generate deviations from
unitarity in the leptonic mixing matrix for charged currents. We reconsidered
this idea in the context of the inverse seesaw and evaluated its impact on the
well measured ratio $R_K$. We show that the current experimental bound can be
saturated in agreement with the different experimental and observational
constraints. Similar results can be obtained when considering the ratio
$R_\pi$.


title:
Production of charged pions, kaons and protons in e+e- annihilations
  into hadrons at sqrt{s} = 10.54 GeV

abstract:
  Inclusive production cross sections of $\pi^\pm$, $K^\pm$ and $p\bar{p}$ per
hadronic $e^+e^-$ annihilation event in $e^+e^-$ are measured at a
center-of-mass energy of 10.54 GeV, using a relatively small sample of very
high quality data from the BaBar experiment at the PEP-II $B$-factory at the
SLAC National Accelerator Laboratory. The drift chamber and Cherenkov detector
provide clean samples of identified $\pi^\pm$, $K^\pm$ and $p\bar{p}$ over a
wide range of momenta. Since the center-of-mass energy is below the threshold
to produce a $B\bar{B}$ pair, with $B$ a bottom-quark meson, these data
represent a pure $e^+e^- \rightarrow q\bar{q}$ sample with four quark flavors,
and are used to test QCD predictions and hadronization models. Combined with
measurements at other energies, in particular at the $Z^0$ resonance, they also
provide precise constraints on the scaling properties of the hadronization
process over a wide energy range.


title: Hard Lefschetz Theorem for Sasakian manifolds

abstract:
  We prove that on a compact Sasakian manifold $(M, \eta, g)$ of dimension
$2n+1$, for any $0 \le p \le n$ the wedge product with $\eta \wedge (d\eta)^p$
defines an isomorphism between the spaces of harmonic forms
$\Omega^{n-p}_\Delta (M)$ and $\Omega^{n+p+1}_\Delta (M)$. Therefore it induces
an isomorphism between the de Rham cohomology spaces $H^{n-p}(M)$ and
$H^{n+p+1}(M)$. Such isomorphism is proven to be independent of the choice of a
compatible Sasakian metric on a given contact manifold. As a consequence, an
obstruction for a contact manifold to admit Sasakian structures is found.


title: Polyakov-Quark-Meson-Diquark Model for two-color QCD

abstract:
  We present an update on the phase diagram of two-color QCD from a chiral
effective model approach based on a quark-meson-diquark model using the
Functional Renormalization Group (FRG). We discuss the impact of perturbative
UV contributions, the inclusion of gauge field dynamics via a phenomenological
Polyakov loop potential, and the impact of matter backcoupling on the gauge
sector. The corresponding phase diagram including these effects is found to be
in qualitative agreement with recent lattice investigations.


title: Defining a Simulation Strategy for Cancer Immunocompetence

abstract:
  Although there are various types of cancer treatments, none of these
currently take into account the effect of ageing of the immune system and hence
altered responses to cancer. Recent studies have shown that in vitro
stimulation of T cells can help in the treatment of patients. There are many
factors that have to be considered when simulating an organism's
immunocompetence. Our particular interest lies in the study of loss of
immunocompetence with age. We are trying to answer questions such as: Given a
certain age of a patient, how fit is their immune system to fight cancer? Would
an immune boost improve the effectiveness of a cancer treatment given the
patient's immune phenotype and age? We believe that understanding the processes
of immune system ageing and degradation through computer simulation may help in
answering these questions. Specifically, we have decided to look at the change
in numbers of naive T cells with age, as they play a important role in
responses to cancer and anti-tumour vaccination. In this work we present an
agent-based simulation model to understand the interactions which influence the
naive T cell populations over time. Our agent model is based on existing
mathematical system dynamic model, but in comparisons offers better scope for
customisation and detailed analysis. We believe that the results obtained can
in future help with the modelling of T cell populations inside tumours.


title:
Invariants and Flavour in the General Two Higgs Doublet Model (Moriond
  QCD2013)

abstract:
  We construct weak basis invariants which can give insight into the physical
implications of any flavour model, written in an arbitrary weak basis (WB) in
the context of 2HDM.


title:
Packing of softly repulsive particles in a spherical box - a generalised
  Thomson problem

abstract:
  We study the (near or close to) ground state distribution of N softly
repelling particles trapped in the interior of a spherical box. The charges
mutually interact via an inverse power law potential of the form $1/r^\gamma$.
We study three regimes in which the charges form an single spherical shell at
the edge of the box ($\gamma=1$), a series of concentric shells of increasing
density ($\gamma=2$) and $\gamma=12$ for which the charges form shells with a
more uniform charge distribution. We conduct numerical simulations for clusters
containing up to 5000 charges and compare charge density across the system with
continuum limit results. The agreement between numerical (discrete) results and
the continuum limit is found to improve with increasing N.


title: Fluid Inflation

abstract:
  In this work we present an inflationary mechanism based on fluid dynamics.
Starting with the action for a single barotropic perfect fluid, we outline the
procedure to calculate the power spectrum and the bispectrum of the curvature
perturbation. It is shown that a perfect barotropic fluid naturally gives rise
to a non-attractor inflationary universe in which the curvature perturbation is
not frozen on super-horizon scales. We show that a scale-invariant power
spectrum can be obtained with the local non-Gaussianity parameter $f_{NL}=
5/2$.


title:
Stirring N-body systems II: Necessary conditions for the dark matter
  attractor

abstract:
  We study the evolution of the phase-space of collisionless N-body systems
under repeated stirrings or perturbations, which has been shown to lead to a
convergence towards a limited group of end states. This so-called attractor was
previously shown to be independent of the initial system and environmental
conditions. However the fundamental reason for its appearance is still unclear.
It has been suggested that the origin of the attractor may be either radial
infall (RI), the radial orbit instability (ROI), or energy exchange which, for
instance, happens during violent relaxation. Here we examine the effects of a
set of controlled perturbations, referred to as `kicks', which act in addition
to the standard collisionless dynamics by allowing pre-specified instantaneous
perturbations in phase-space. We first demonstrate that the attractor persists
in the absence of RI and ROI by forcing the system to expand. We then consider
radial velocity kicks in a rigid potential and isotropic velocity kicks, since
there are no energy exchanges in these two recipes of kicks. We find that these
kicks do not lead to the attractor, indicating that the energy exchange in a
dynamic potential is indeed the physical mechanism responsible for the
attractor.


title: Neutrino Propagation in Matter

abstract:
  We describe the effects of neutrino propagation in the matter of the Earth
relevant for experiments with atmospheric and accelerator neutrinos and aimed
at the determination of the neutrino mass hierarchy and CP-violation. These
include (i) the resonance enhancement of neutrino oscillations in matter with
constant or nearly constant density, (ii) adiabatic conversion in matter with
slowly changing density, (iii) parametric enhancement of oscillations in a
multi-layer medium, (iv) oscillations in thin layers of matter. We present the
results of semi-analytic descriptions of flavor transitions for the cases of
small density perturbations, in the limit of large densities and for small
density widths. Neutrino oscillograms of the Earth and their structure after
determination of the 1-3 mixing are described. A possibility to identify the
neutrino mass hierarchy with the atmospheric neutrinos and multi-megaton scale
detectors having low energy thresholds is explored. The potential of future
accelerator experiments to establish the hierarchy is outlined.


title:
Numerical Methods of Optimal Accuracy for Weakly Singular Volterra
  Integral Equations

abstract:
  Weakly singular Volterra integral equations of the different types are
considered. The construction of accuracy-optimal numerical methods for
one-dimensional and multidimensional equations is discussed. Since this
question is closely related with the optimal approximation problem, the orders
of the Babenko and Kolmogorov \(n-\)widths of compact sets from some classes of
functions have been evaluated. In conclusion we adduce some numerical
illustrations for 2-D Volterra equations.


title:
Assessing Student Learning in Middle-Division Classical Mechanics/Math
  Methods

abstract:
  Reliable and validated assessments of introductory physics have been
instrumental in driving curricular and pedagogical reforms that lead to
improved student learning. As part of an effort to systematically improve our
sophomore-level Classical Mechanics and Math Methods course (CM 1) at CU
Boulder, we are developing a tool to assess student learning of CM 1 concepts
in the upper-division. The Colorado Classical Mechanics/Math Methods Instrument
(CCMI) builds on faculty-consensus learning goals and systematic observations
of student difficulties. The result is a 9-question open-ended post-test that
probes student learning in the first half of a two-semester classical mechanics
/ math methods sequence. In this paper, we describe the design and development
of this instrument, its validation, and measurements made in classes at CU
Boulder.


title: Robust Support Vector Machines for Speaker Verification Task

abstract:
  An important step in speaker verification is extracting features that best
characterize the speaker voice. This paper investigates a front-end processing
that aims at improving the performance of speaker verification based on the
SVMs classifier, in text independent mode. This approach combines features
based on conventional Mel-cepstral Coefficients (MFCCs) and Line Spectral
Frequencies (LSFs) to constitute robust multivariate feature vectors. To reduce
the high dimensionality required for training these feature vectors, we use a
dimension reduction method called principal component analysis (PCA). In order
to evaluate the robustness of these systems, different noisy environments have
been used. The obtained results using TIMIT database showed that, using the
paradigm that combines these spectral cues leads to a significant improvement
in verification accuracy, especially with PCA reduction for low signal-to-noise
ratio noisy environment.


title:
Frequency estimation based on Hankel matrices and the alternating
  direction method of multipliers

abstract:
  We develop a parametric high-resolution method for the estimation of the
frequency nodes of linear combinations of complex exponentials with exponential
damping. We use Kronecker's theorem to formulate the associated nonlinear least
squares problem as an optimization problem in the space of vectors generating
Hankel matrices of fixed rank. Approximate solutions to this problem are
obtained by using the alternating direction method of multipliers. Finally, we
extract the frequency estimates from the con-eigenvectors of the solution
Hankel matrix. The resulting algorithm is simple, easy to implement and can be
applied to data with equally spaced samples with approximation weights, which
for instance allows cases of missing data samples. By means of numerical
simulations, we analyze and illustrate the excellent performance of the method,
attaining the Cram\'er-Rao bound.


title:
A Heavy Ion Fireball freeze-out Dipion Cocktail for Au-Au Collisions at
  $\sqrt{s_{NN}}$=200 GeV (Part1)

abstract:
  In this paper we develop all the ingredients that come into play in the
freeze-out of the heavy ion fireball for Au-Au collisions at
$\sqrt{s_{NN}}$=200 GeV into dipions. The resonance production of particles
that decay into dipions plus minijets that also decay into dipions are
explored. The final state re-scattering of the pions from minijets play an
important role in the mass spectrum of the cocktail. Mass shifts due to minijet
interference which depend on the volume of the re-scattering pions is
presented. The effective mass balance function is explained. The dipion mass
spectrum within a $p_t$ range(intermediate $p_t$) is fitted using thermal and
minijet amplitudes.


title: Interaction of eta mesons with nuclei

abstract:
  Back in the mid eighties, a new branch of investigation which was related to
the interaction of eta mesons with nuclei came into existence. It started with
the theoretical prediction of possible exotic states of eta mesons and nuclei
bound by the strong interaction and later developed into an extensive
experimental program to search for such unstable states as well as understand
the underlying interaction via eta meson producing reactions. The vast
literature of experimental as well as theoretical works which studied various
aspects of eta producing reactions such as the $\pi ^+$ $n$ $\to \eta p$, $p d
\to ^3$He $\eta$, $p \,^6$Li $\to ^7$Be $\eta$ and $\gamma ^3$He $\to \eta$ X,
to name a few, had but one objective in mind: to understand the eta - nucleon
($\eta N$) and hence the $\eta$-nucleus interaction which could explain the
production data and confirm the existence of some $\eta$-mesic nuclei. In spite
of these efforts, there remain uncertainties in the knowledge of the $\eta N$
and hence the $\eta$-nucleus interaction. The present review is hence an
attempt to bind together the findings in these works and draw some global and
specific conclusions which can be useful for future explorations.


title:
Macroscopic quantum tunneling of magnetization explored by
  quantum-first-order reversal curves (QFORC)

abstract:
  A novel method to study the fundamental problem of quantum double well
potential systems that display magnetic hysteresis is proposed. The method,
coined quantum-first-order reversal curve (QFORC) analysis, is inspired by the
conventional first-order reversal curve (FORC) protocol, based on the Preisach
model for hysteretic phenomena. We successfully tested the QFORC method in the
peculiar hysteresis of the Mn12Ac molecular magnet, which is governed by
macroscopic quantum tunneling of magnetization. The QFORC approach allows one
to quickly reproduce well the experimental magnetization behavior, and more
importantly to acquire information that is difficult to infer from the usual
methods based on matrix diagonalization. It is possible to separate the thermal
activation and tunneling contributions from the magnetization variation, as
well as understand each experimentally observed jump of the magnetization curve
and associate them with specific quantum transitions.


title:
Boundary layer dynamics at the transition between the classical and the
  ultimate regime of Taylor-Couette flow

abstract:
  Direct numerical simulations of turbulent Taylor-Couette flow are performed
up to inner cylinder Reynolds numbers of {Re_i=10^5} for a radius ratio of
{\eta=r_i/r_o=0.714} between the inner and outer cylinder. With increasing
{Re_i}, the flow undergoes transitions between three different regimes: (i) a
flow dominated by large coherent structures, (ii) an intermediate transitional
regime, and (iii) a flow with developed turbulence. In the first regime the
large--scale rolls completely drive the meridional flow while in the second one
the coherent structures recover only on average. The presence of a mean flow
allows for the coexistence of laminar and turbulent boundary layer dynamics. In
the third regime the mean flow effects fade away and the flow becomes dominated
by plumes. The effect of the local driving on the azimuthal and angular
velocity profiles is quantified, in particular we show when and where those
profiles develop.


title: A thermodynamic description of colloidal glasses

abstract:
  The phase behavior of hard-sphere particles interacting with a short-ranged
potential is studied in the limit of infinite space dimensionality via the
Franz-Parisi approach and the replica method of disordered systems. For an
attractive square-well potential the phase diagram exhibits reentrancy of the
liquid-glass transition, multiple glass states and glass-glass transition. For
a repulsive square shoulder potential no such special features are observed.
Our results show that the Franz-Parisi approach can be consistently extended to
deal with higher-order glass singularities and that interparticle attraction is
crucial for complex glassy behavior in large enough dimensions, at least for
monodisperse systems.


title:
The Herschel Exploitation of Local Galaxy Andromeda (HELGA). VI. The
  distribution and properties of molecular cloud associations in M31

abstract:
  In this paper we present a catalogue of Giant Molecular Clouds (GMCs) in the
Andromeda (M31) galaxy extracted from the Hershel Exploitation of Local Galaxy
Andromeda (HELGA) dataset. GMCs are identified from the Herschel maps using a
hierarchical source extraction algorithm. We present the results of this new
catalogue and characterise the spatial distribution and spectral energy
properties of its clouds based on the radial dust/gas properties found by Smith
et al (2012). 236 GMCs in the mass range 10^4-10^7 M_sol are identified, their
cumulative mass distribution is found to be proportional to M^-1.45 in
agreement with earlier studies. The GMCs appear to follow the same cloud mass
to L_CO correlation observed in the Milky Way. However, comparison between this
catalogue and interferometry studies also shows that the GMCs are substructured
below the Herschel resolution limit suggesting that we are observing
associations of GMCs. Following Gordon et al. (2006), we study the spatial
structure of M31 by splitting the observed structure into a set of spiral arms
and offset rings. We fit radii of 10.5 and 15.5 kpc to the two most prominent
rings. We then fit a logarithmic spiral with a pitch angle of 8.9 deg to the
GMCs not associated with either ring. Lastly, we comment upon the effects of
deprojection on our results and investigate the effect different models for
M31's inclination will have upon the projection of an unperturbed spiral arm
system.


title:
Analytic approximation of transmutation operators and applications to
  highly accurate solution of spectral problems

abstract:
  A method for approximate solution of spectral problems for Sturm-Liouville
equations based on the construction of the Delsarte transmutation operators is
presented. In fact the problem of numerical approximation of solutions and
eigenvalues is reduced to approximation of a primitive of the potential by a
finite linear combination of generalized wave polynomials introduced in
arXiv:1208.5984, arXiv:1208.6166. The method allows one to compute both lower
and higher eigendata with an extreme accuracy.


title:
Chandra Spectroscopy of MAXI J1305-704: Detection of an Infalling Black
  Hole Disk Wind?

abstract:
  We report on a Chandra/HETG X-ray spectrum of the black hole candidate MAXI
J1305-704. A rich absorption complex is detected in the Fe L band, including
density-sensitive lines from Fe XX, XXI, and XXII. Spectral analysis over three
bands with photoionization models generally requires a gas density of n > 1
E+17 cm^-3. Assuming a luminosity of L = 1 E+37 erg/s, fits to the 10-14 A band
constrain the absorbing gas to lie within r = 3.9(7) E+3 km from the central
engine, or about r = 520 +/- 90 (M/5 Msun) r_g, where r_g = GM/c^2. At this
distance from the compact object, gas in Keplerian orbits should have a
gravitational red-shift of z = v/c ~ 3 +/- 1 E-3 (M/5 Msun), and any tenuous
inflowing gas should have a free-fall velocity of v/c ~ 6 +/- 1 E-2 (M/5
Msun)^1/2. The best-fit single-zone photoionization models measure a red-shift
of v/c = 2.6-3.2 E-3. Models with two zones provide significantly improved
fits; the additional zone is measured to have a red-shift of v/c =4.6-4.9 E-2
(models including two zones suggest slightly different radii and may point to
lower densities). Thus, the shifts are broadly consistent with the
photoionization radius. The results may be explained in terms of a "failed
wind" like those predicted in some numerical simulations. We discuss our
results in the context of accretion flows across the mass scale, and the
potential role of failed winds in black hole state transitions.


title:
The pion vector form factor from lattice QCD and NNLO chiral
  perturbation theory

abstract:
  We present a comprehensive study of the electromagnetic form factor, the
decay constant and the mass of the pion computed in lattice QCD with two
degenerate O(a)-improved Wilson quarks at three different lattice spacings in
the range 0.05-0.08fm and pion masses between 280 and 630MeV at m_pi L >~ 4.
Using partially twisted boundary conditions and stochastic estimators, we
obtain a dense set of precise data points for the form factor at very small
momentum transfers, allowing for a model-independent extraction of the charge
radius. Chiral Perturbation Theory (ChPT) augmented by terms which model
lattice artefacts is then compared to the data. At next-to-leading order the
effective theory fails to produce a consistent description of the full set of
pion observables but describes the data well when only the decay constant and
mass are considered. By contrast, using the next-to-next-to-leading order
expressions to perform global fits result in a consistent description of all
data. We obtain <r^2_pi>=0.481(33)(13)fm^2 as our final result for the charge
radius at the physical point. Our calculation also yields estimates for the
pion decay constant in the chiral limit, F_pi/F=1.080(16)(6), the quark
condensate, Sigma^{1/3}_MSbar(2GeV)=261(13)(1)MeV and several low-energy
constants of SU(2) ChPT.


title: Scaling Properties of Paths on Graphs

abstract:
  Let $G$ be a directed graph on finitely many vertices and edges, and assign a
positive weight to each edge on $G$. Fix vertices $u$ and $v$ and consider the
set of paths that start at $u$ and end at $v$, self-intersecting in any number
of places along the way. For each path, sum the weights of its edges, and then
list the path weights in increasing order. The asymptotic behaviour of this
sequence is described, in terms of the structure and type of strongly connected
components on the graph. As a special case, for a Markov chain the asymptotic
probability of paths obeys either a power law scaling or a weaker type of
scaling, depending on the structure of the transition matrix. This generalizes
previous work by Mandelbrot and others, who established asymptotic power law
scaling for special classes of Markov chains.


title: Reinforcement learning with restrictions on the action set

abstract:
  Consider a 2-player normal-form game repeated over time. We introduce an
adaptive learning procedure, where the players only observe their own realized
payoff at each stage. We assume that agents do not know their own payoff
function, and have no information on the other player. Furthermore, we assume
that they have restrictions on their own action set such that, at each stage,
their choice is limited to a subset of their action set. We prove that the
empirical distributions of play converge to the set of Nash equilibria for
zero-sum and potential games, and games where one player has two actions.


title: Phase diagram of Yang-Mills theories in the presence of a theta term

abstract:
  We study the phase diagram of non-Abelian pure gauge theories in the presence
of a topological theta term. The dependence of the deconfinement temperature on
theta is determined on the lattice both by analytic continuation and by
reweighting, obtaining consistent results. The general structure of the diagram
is discussed on the basis of large-N considerations and of the possible
analogies and dualities existing with the phase diagram of QCD in presence of
an imaginary baryon chemical potential.


title: Top-down Beyond the Standard Model Review

abstract:
  The recent discovery of the Standard Model boson (SMS) and direct searches
place new constraints and a new perspective on New Physics models. I mostly
review supersymmetric model building, with special emphasizes on predictions of
flavor models on superpartner spectra and inverted hierarchy models, mini-split
models, very low-scale supersymmetry breaking predictions and some string
theory inspired low-energy spectra.


title:
Symmetry and plate-like convection in fluids with temperature-dependent
  viscosity

abstract:
  We explore the instabilities developed in a fluid in which viscosity depends
on temperature. In particular, we consider a dependency that models a very
viscous (and thus rather rigid) lithosphere over a convecting mantle. To this
end, we study a 2D convection problem in which viscosity depends on temperature
by abruptly changing its value by a factor of 400 within a narrow temperature
gap. We conduct a study which combines bifurcation analysis and time-dependent
simulations. Solutions such as limit cycles are found that are fundamentally
related to the presence of symmetry. Spontaneous plate-like behaviors that
rapidly evolve towards a stagnant lid regime emerge sporadically through abrupt
bursts during these cycles. The plate-like evolution alternates motions towards
either the right or the left, thereby introducing temporary asymmetries on the
convecting styles. Further time-dependent regimes with stagnant and plate-like
lids are found and described.

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


title:
A framework to investigate the immittance responses for finite
  length-situations: fractional diffusion equation, reaction term, and boundary
  conditions

abstract:
  The Poisson-Nernst-Planck (PNP) diffusional model for the immittance or
impedance spectroscopy response of an electrolytic cell in a finite-length
situation is extended to a general framework. In this new formalism, the bulk
behavior of the mobile charges is governed by a fractional diffusion equation
in the presence of a reaction term. The solutions have to satisfy a general
boundary condition embodying, in a single expression, most of the surface
effects commonly encountered in experimental situations. Among these effects,
we specifically consider the charge transfer process from an electrolytic cell
to the external circuit and the adsorption-desorption phenomenon at the
interfaces. The equations are exactly solved in the small AC signal
approximation and are used to obtain an exact expression for the electrical
impedance as a funcion of the frequency. The predictions of the model are
compared to and found to be in good agreement with the experimental data
obtained for an electrolytic solution of CdCl2H20.


title: RNA topology remolds electrostatic stabilization of viruses

abstract:
  Simple RNA viruses efficiently encapsulate their genome into a nano-sized
protein shell: the capsid. Spontaneous co-assembly of the genome and the capsid
proteins is driven predominantly by electrostatic interactions between the
negatively charged RNA and the positively charged inner capsid wall. Using
field theoretic formulation we show that the inherently branched RNA secondary
structure allows viruses to maximize the amount of encapsulated genome and make
assembly more efficient, allowing viral RNAs to out-compete cellular RNAs
during replication in infected host cells.


title: Analytic physical model of anisotropic anomalous diffusion

abstract:
  The temporal Fokker-Planck equation is analytically integrated in an
arbitrary number of spatial dimensions but with the 2D and 3D results
highlighted. It is shown that a temporal power-law ansatz for the anisotropic
diffusion coefficients leads naturally to a physically reasonable model of
normal and anomalous diffusion with drift. An interpretation of the drift and
diffusion coefficients is provided and the analytic growth rate of the area and
volume of uncertainty is determined. It is shown that the asymptotic growth of
the uncertainty in the volume of space about the mean position is proportional
to the square-root of time raised to the power of the sum over all exponents of
the anisotropic diffusion coefficients.


title:
Contribution of the Electron-Phonon Coupling to the Pairing Interaction
  in LiFeAs

abstract:
  The coupling strengths for intra- and inter-band electron-phonon pair
scattering are calculated for LiFeAs. While the sum of these couplings, which
gives the total electron-phonon coupling $\lambda$, is of order 0.2, we find
that their contribution to the presumed $s^\pm$ superconducting state is
reduced by approximately an order of magnitude.


title: Naturalness, Supersymmetry and Light Higgsinos: A Snowmass Whitepaper

abstract:
  We show that the electroweak fine-tuning parameter \Delta_{\rm EW} derived
from the well-known electroweak symmetry breaking condition written in terms of
weak scale parameters leads to {\it a bound on fine-tuning in the MSSM} and
explain its utility for phenomenological analyses. We argue that a small
magnitude of the mu parameter, and the concomitant presence of light higgsinos,
is the most basic consequence of naturalness in SUSY models, and list the
resulting implications of this for experiments at the LHC and at future e^+e^-
colliders.


title: Temperley-Lieb R-matrices from generalized Hadamard matrices

abstract:
  New sets of rank n-representations of Temperley-Lieb algebra TL_N(q) are
constructed. They are characterized by two matrices obeying a generalization of
the complex Hadamard property. Partial classifications for the two matrices are
given, in particular when they reduce to Fourier or Butson matrices.


title:
Edge excitation geometry for studying intrinsic emission spectra of bulk
  n-InP

abstract:
  The shape of the photoluminescence line excited at an edge face of InP wafer
and recorded from the broadside is used to investigate the intrinsic emission
spectrum. The procedure is much less sensitive to the surface properties and
the carrier kinetics than the conventional methods used with the reflection or
transmission geometry of photoluminescence. Our method provides a tool for
studying the effects of non-equilibrium distribution of minority carriers in
doped direct-band semiconductors.


title:
The Imaginary Part of the Static Potential in Strongly Coupled
  Anisotropic Plasma

abstract:
  Using the gauge/gravity duality we study the imaginary part of the static
potential associated to the thermal width in finite temperature strongly
coupled anisotropic plasma. We firstly derive the potential for a generic
anisotropic background. Then we apply our formulas to a theory where the
anisotropy has been generated by a space dependent axion term. We find that
using our method there exist a peculiar turning point in the imaginary part of
the potential, similar to the one appearing in the real part. The presence of
anisotropy leads to decrease of the imaginary potential, where larger decrease
happens along the anisotropic direction when the temperature is kept fixed.
When the entropy density is fixed, increase happens along the parallel
direction while along the transverse plane we observe a decrease. To estimate
the thermal width we use an approximate extrapolation beyond the turning point
and we find a decrease in presence of the anisotropy, independently of the
comparison scheme used.


title: Another proof of Wilmes' conjecture

abstract:
  We present a new proof of the monomial case of Wilmes' conjecture, which
gives a formula for the coarsely-graded Betti numbers of the G-parking function
ideal in terms of maximal parking functions of contractions of G. Our proof is
via poset topology and relies on a theorem of Gasharov, Peeva, and Welker that
connects the Betti numbers of a monomial ideal to the topology of its
lcm-lattice.


title: On the Parameterized Complexity of the Maximum Edge Coloring Problem

abstract:
  We investigate the parameterized complexity of the following edge coloring
problem motivated by the problem of channel assignment in wireless networks.
For an integer q>1 and a graph G, the goal is to find a coloring of the edges
of G with the maximum number of colors such that every vertex of the graph sees
at most q colors. This problem is NP-hard for q>1, and has been well-studied
from the point of view of approximation. Our main focus is the case when q=2,
which is already theoretically intricate and practically relevant. We show
fixed-parameter tractable algorithms for both the standard and the dual
parameter, and for the latter problem, the result is based on a linear vertex
kernel.


title: On certain classes of graceful lobsters

abstract:
  A graph G=(V,E) with m edges is graceful if it has a distinct vertex labeling
f, a map from V into the set{0,1,2,3,...,m} which induces a distinct edge
labeling |f(u)-f(v)| for edges uv in E. The famous Ringel-Kotzig conjecture
(1964) is that all trees are graceful. The base of a tree T is obtained from T
by deleting its one-degree vertices. A caterpillar is a tree whose base is a
path and a lobster is a tree whose base is a caterpillar. Paths and
caterpillars are known to be graceful. Next it was conjectured by Bermond
(1979) that all lobsters are graceful. In this paper we describe various
methods of joining graceful graphs and \alpha-labeled graphs using the
adjacency matrix characterization that initiated by Bloom (1979) and others. We
apply these results to obtain some classes of graceful lobsters and indicate
how to obtain some others.


title:
Phase diagram of the magnetized planar Gross-Neveu model beyond the
  large-N approximation

abstract:
  The phase diagram and thermodynamic properties of the (2+1)-dimensional
Gross-Neveu model are studied in the presence of a constant magnetic field. The
optimized perturbation theory (OPT) is used to obtain results going beyond the
large-N approximation. The free energy and the complete phase diagram of the
model, in terms of temperature, chemical potential and magnetic field are
obtained and studied in details. By comparing the results from the OPT and the
large-N approximation, we conclude that finite N effects favor the phenomenon
of inverse magnetic catalysis when the coupling constant is negative. We show
that with the OPT the value of the coexistence chemical potential at vanishing
temperature always decreases with the magnetic field. This is opposite to what
is seen in the large-N approximation, where for large magnetic fields the
coexistence chemical potential starts again to increase. Likewise, at finite
temperature, the value of the chemical potential at the tricritical point also
decreases with the magnetic field in the OPT case. Consequently, the shape of
the phase diagrams predicted by the OPT and by the large-N approximation look
very different in the presence of high magnetic fields. Finally, for small
values of magnetic field and temperature, we identify the presence of possible
intermediate nonchiral phase transitions when varying the chemical potential.
We show that these phenomena are not an artifact of the large-N approximation
and that they also occur within the OPT framework. These intermediate
transitions are interpreted to be a consequence of the de Haas--van Alphen
oscillations. We also explain why this type of phenomenon can happen in general
for negative couplings but not for positive couplings.


title:
Set theory and topology. An introduction to the foundations of analysis.
  Part I: Sets, relations, numbers

abstract:
  We provide a formal introduction into the classic theorems of general
topology and its axiomatic foundations in set theory. Starting from ZFC, the
exposition in this first part includes relation and order theory as well as a
construction of number systems.


title: Slimy hairs: Hair sensors made with slime mould

abstract:
  Slime mould Physarum polycephalum is a large single cell visible by unaided
eye. We design a slime mould implementation of a tactile hair, where the slime
mould responds to repeated deflection of hair by an immediate high-amplitude
spike and a prolonged increase in amplitude and width of its oscillation
impulses. We demonstrate that signal-to-noise ratio of the Physarum tactile
hair sensor averages near six for the immediate response and two for the
prolonged response.


title:
Neutral $\rho$ and $A$ mesons in magnetic field in SU(2) lattice gauge
  theory

abstract:
  Correlators of vector, axial and pseudoscalar currents have been calculated
in external strong magnetic field in SU(2) gluodynamics on the lattice. Neutral
$\rho$ and $A$ meson masses with a zero spin projection to the axis parallel to
the external magnetic field $B$ are calculated. The mass of the neutral $\rho$
meson with zero spin decreases with increasing of the magnetic field for
available values of the magnetic field $eB\lesssim 2-2.5\, \Gev^2$, such
behavior is necessary for a condensation of $\rho$ mesons in a strong magnetic
field.


title: High Q SiC microresonators

abstract:
  We demonstrate photonic devices based on standard 3C SiC epitaxially grown on
silicon. We achieve high optical confinement by taking advantage of the high
stiffness of SiC and undercutting the underlying silicon substrate. We
demonstrate a 20 um radius suspended microring resonator with Q of 18000
fabricated on commercially available SiC-on-silicon substrates.


title: The Sounds of the QCD Phase Transition

abstract:
  Hydrodynamic description of a fireball produced in high energy heavy ion
collisions has been recently supplemented by a very successful study of
acoustic perturbation created by the initial state perturbations. We discuss
sound produced at later stages of the collision, as the temperature drops below
critical, $T<T_c$, and originated from the Rayleigh-type collapse of the QGP
clusters. In certain analytic approximation we study distorted "sound spheres"
and calculate modifications of the particle spectra and two-particle
correlators induced by them. Unlike for initial state perturbations studied
previously, we propose to look for those late-time sounds using rapidity
correlations, rather than the azimuthal angles of the particles. We then
summarize known data on rapidity correlations from RHIC and LHC, suggesting
that the widening of those can be the first signature of the late-time sounds.


title:
Structure and coarsening at the surface of a dry three-dimensional
  aqueous foam

abstract:
  We utilize total-internal reflection to isolate the two-dimensional `surface
foam' formed at the planar boundary of a three-dimensional sample. The
resulting images of surface Plateau borders are consistent with Plateau's laws
for a truly two-dimensional foam. Samples are allowed to coarsen into a
self-similar scaling state where statistical distributions are independent of
time, except for an overall scale factor. There we find that statistical
measures of side number distributions, size-topology correlations, and bubble
shapes, are all very similar to those for two-dimensional foams. However the
size number distribution is slightly broader and the shapes are slightly more
elongated. A more obvious difference is that T2 processes now include the
creation of surface bubbles, due to rearrangement in the bulk. And von
Neumann's law is dramatically violated for individual bubbles. But
nevertheless, our most striking finding is that von Neumann's law appears to
holds on average. Namely the average rate of area change for surface bubbles
appears to be proportional to the number of sides minus six, but with
individual bubbles showing a distribution of deviations from this average
behavior.


title:
The Galaxy Counterparts of the two high-metallicity DLAs at z=2.412 and
  z=2.583 towards Q0918+1636

abstract:
  The quasar Q0918+1636 (z=3.07) has two intervening high-metallicity Damped
Lyman-alpha Absorbers (DLAs) along the line of sight, at redshifts of z=2.412
and 2.583. The z=2.583 DLA is located at a large impact parameter of 16.2 kpc,
and despite this large impact parameter it has a very high metallicity
(consistent with solar), a substantial fraction of H_2 molecules, and it is
dusty as inferred from the reddened spectrum of the background QSO. The z=2.412
DLA has a metallicity of [M/H]=-0.6 (based on ZnII and SiII). In this paper we
present new observations of this interesting sightline. HST/WFC3 imaging was
obtained in the F606W, F105W and F160W bands. This is complemented by
ground-based imaging in the u-, g-bands as well as K_s observations in the
near-infrared (NIR). In addition, we present further spectroscopy with the
ESO/VLT X-Shooter spectrograph. Based on these observations we obtain the
following results: By fitting stellar population synthesis models to the
photometric SED we constrain the physical properties of the z=2.583 DLA galaxy,
and we infer its morphology by fitting a Sersic model to its surface brightness
profile. We find it to be a relatively massive (M_star 10^10 M_sun), strongly
star-forming (SFR~30 M_sun / yr, dusty (E_(B-V)=0.4) galaxy with a disk-like
morphology. We detect most of the strong emission lines from the z=2.583 DLA
[OIII],3727, [OIII],4960, [OIII],5007, Hbeta, and Halpha, albeit at low
signal-to-noise (SN) ratio except for the [OIII],5007 line. We also detect
[OIII],5007 emission from the galaxy counterpart of the z=2.412 DLA at a small
impact parameter (<2 kpc). Overall our findings are consistent with the
emerging picture that high-metallicity DLAs are associated with relatively
(compared to typical DLAs) luminous and massive galaxy counterparts.


title:
Global fit to Higgs signal strengths and couplings and implications for
  extended Higgs sectors

abstract:
  The most recent LHC data have provided a considerable improvement in the
precision with which various Higgs production and decay channels have been
measured. Using all available public results from ATLAS, CMS and the Tevatron,
we derive for each final state the combined confidence level contours for the
signal strengths in the (gluon fusion + ttH associated production) versus
(vector boson fusion + VH associated production) space. These "combined signal
strength ellipses" can be used in a simple, generic way to constrain a very
wide class of New Physics models in which the couplings of the Higgs boson
deviate from the Standard Model prediction. Here, we use them to constrain the
reduced couplings of the Higgs boson to up-quarks, down-quarks/leptons and
vector boson pairs. We also consider New Physics contributions to the
loop-induced gluon-gluon and photon-photon couplings of the Higgs, as well as
invisible/unseen decays. Finally, we apply our fits to some simple models with
an extended Higgs sector, in particular to Two-Higgs-Doublet models of Type I
and Type II, the Inert Doublet model, and the Georgi-Machacek triplet Higgs
model.


title: A coupling approach to random circle maps expanding on the average

abstract:
  We study random circle maps that are expanding on the average. Uniform bounds
on neither expansion nor distortion are required. We construct a coupling
scheme, which leads to exponential convergence of measures (memory loss) and
exponential mixing. Leveraging from the structure of the associated correlation
estimates, we prove an almost sure invariance principle for vector-valued
observables. The motivation for our paper is to explore these methods in a
nonuniform random setting.


title:
Matrix model for deconfinement in an SU(2) gauge theory in 2+1
  dimensions

abstract:
  We use matrix models to characterize deconfinement at a nonzero temperature T
for an SU(2) gauge theory in three spacetime dimensions. At one loop order, the
potential for a constant vector potential A0 is ~T^3 times a trilogarithm
function of A0/T. In addition, we add various nonperturbative terms to model
deconfinement. The parameters of the model are adjusted by fitting the lattice
results for the pressure. The nonperturbative terms are dominated by a constant
term ~T^2Td, where Td is the temperature for deconfinement. Besides this
constant, we add terms which are nontrivial functions of A0/T, both ~T^2Td and
~TTd^2. There is only a mild sensitivity to the details of these nonconstant
terms. Overall we find a good agreement with the lattice results. For the
pressure, the conformal anomaly, and the Polyakov loop the nonconstant terms
are relevant only in a narrow region below ~1.2Td. We also compute the 't Hooft
loop, and find that the details of the nonconstant terms enter in a much wider
region, up to ~4Td.


title: A Holographic Model of Heavy-light Mesons

abstract:
  We construct a holographic model of heavy-light mesons by extending the
AdS/QCD to incorporate the behavior of the heavy quark limit. In that limit,
the QCD dynamics is governed by the light quark and the heavy quark simply
plays the role of a static color source. The heavy quark spin symmetry can be
treated as a global symmetry in the AdS bulk. As a consequence, the heavy-light
mesons are mapped to "fermions" in the AdS theory. The light flavor chiral
symmetry is naturally built in by this construction, and its breaking produces
the splitting of the parity-doubled heavy-light meson states. The scaling
dependences of physical quantities on the heavy quark mass in the heavy quark
effective theory are reproduced. The mass spectra and decay constants of the B
and D mesons can be well fit by suitable choices of model parameters. The
couplings between the heavy-light mesons and the pions are also calculated. The
holographic model may capture the essence of the long distance effects of QCD
and can serve as a useful tool for studying the non-perturbative hadronic
matrix elements involving heavy-light mesons.


title: Transformation of the equatorial proper motion to the Galactic system

abstract:
  I present simple analytical equations to transform proper motion vectors from
equatorial to Galactic coordinates.


title:
Non-linear Representations of the Conformal Group and Mapping of
  Galileons

abstract:
  There are two common non-linear realizations of the 4D conformal group: in
the first, the dilaton is the conformal factor of the effective metric
\eta_{\mu\nu} e^{-2 \pi}; in the second it describes the fluctuations of a
brane in AdS_5. The two are related by a complicated field redefinition, found
by Bellucci, Ivanov and Krivonos (2002) to all orders in derivatives. We show
that this field redefinition can be understood geometrically as a change of
coordinates in AdS_5. In one gauge the brane is rigid at a fixed radial
coordinate with a conformal factor on the AdS_5 boundary, while in the other
one the brane bends in an unperturbed AdS_5. This geometrical picture
illuminates some aspects of the mapping between the two representations. We
show that the conformal Galileons in the two representations are mapped into
each other in a quite non-trivial way: the DBI action, for example, is mapped
into a complete linear combination of all the five Galileons in the other
representation. We also verify the equivalence of the dilaton S-matrix in the
two representations and point out that the aperture of the dilaton light-cone
around non-trivial backgrounds is not the same in the two representations.


title:
Dissipative dynamics of a driven quantum spin coupled to a bath of
  ultracold fermions

abstract:
  We explore the dynamics and the steady state of a driven quantum spin coupled
to a bath of fermions, which can be realized with a strongly imbalanced mixture
of ultracold atoms using currently available experimental tools.
Radio-frequency driving can be used to induce tunneling between the spin
states. The Rabi oscillations are modified due to the coupling of the quantum
spin to the environment, which causes frequency renormalization and damping.
The spin-bath coupling can be widely tuned by adjusting the scattering length
through a Feshbach resonance. When the scattering potential creates a bound
state, by tuning the driving frequency it is possible to populate either the
ground state, in which the bound state is filled, or a metastable state in
which the bound state is empty. In the latter case, we predict an emergent
inversion of the steady-state magnetization. Our work shows that different
regimes of dissipative dynamics can be explored with a quantum spin coupled to
a bath of ultracold fermions.


title:
The dark matter halo concentration and stellar initial mass function of
  a CASSOWARY group

abstract:
  We exploit the group environment of the CAmbridge Sloan Survey Of Wide ARcs
in the skY (CASSOWARY) z=0.3 lens J2158+0257 to measure the group dynamical
mass as a complement to the central dynamical and lensing mass constraints.
Follow-up spectroscopy of candidate group members is performed using VLT/FORS2.
From the resulting N=21 confirmed members we measure the group dynamical mass
by calibrating an analytic tracer mass estimator with cosmological simulations.
The luminosity weighted line-of-sight velocity dispersion and the Einstein
radius of the lens are used as mass probes in the inner regions of the galaxy.
Combining these three observational probes allows us to independently constrain
the mass and concentration of the dark matter halo, in addition to the total
stellar mass of the central galaxy. We find a dark matter halo in remarkably
good agreement with simulations (log_10 M_200/M_sun = 14.2 +/- 0.2, c_200 = 4.4
(+1.6, -1.4)) and a stellar mass-to-light ratio which favors a Salpeter initial
mass function ((M/L)* = 5.7 +/- 1.2). Our measurement of a normal halo
concentration suggests that there is no discrepancy between simulations and
observations at the group mass scale. This is in contrast to the cluster mass
scale for which a number of studies have claimed over-concentrated halos. While
the halo mass is robustly determined, and the halo concentration is not
significantly affected by systematics, the resulting stellar mass-to-light
ratio is sensitive to the choice of stellar parameters, such as density profile
and velocity anisotropy.


title:
Berry phases, current lattices, and suppression of phase transitions in
  a lattice gauge theory of quantum antiferromagnets

abstract:
  We consider a lattice model of two complex scalar matter fields $z_{a},
a=1,2$ under a CP1 constraint $\abs{z_1}^2+\abs{z_2}^2=1$, minimally coupled to
a compact gauge field, with an additional Berry phase term. This model has been
the point of origin for a large body of works addressing novel paradigms for
quantum criticality, in particular spin-quark (spinon) deconfinement in S=1/2
quantum antiferromagnets. We map the model exactly to a link-current model,
which permits the use of classical worm algorithms to study the model in
large-scale Monte Carlo simulations on lattices of size L^3, up to L=360. We
show that the addition of a Berry phase term to the lattice $\CP$-model
suppresses the phase transition in the $\groupO{3}$ universality class of the
$\CP$-model. The link-current formulation of the model is useful in identifying
the mechanism by which the phase transition is suppressed.


title:
UV-Continuum Slopes of >4000 z~4-8 Galaxies from the HUDF/XDF, HUDF09,
  ERS, CANDELS-South, and CANDELS-North Fields

abstract:
  We measure the UV-continuum slope beta for over 4000 high-redshift galaxies
over a wide range of redshifts z~4-8 and luminosities from the HST HUDF/XDF,
HUDF09-1, HUDF09-2, ERS, CANDELS-N, and CANDELS-S data sets. Our new beta
results reach very faint levels at z~4 (-15.5 mag: 0.006 L*(z=3)), z~5 (-16.5
mag: 0.014L*(z=3)), and z~6 and z~7 (-17 mag: 0.025 L*(z=3)). Inconsistencies
between previous studies led us to conduct a comprehensive review of systematic
errors and develop a new technique for measuring beta that is robust against
biases that arise from the impact of noise. We demonstrate, by object-by-object
comparisons, that all previous studies, including our own and those done on the
latest HUDF12 dataset, suffer from small systematic errors in beta. We find
that after correcting for the systematic errors (typically d(beta) ~0.1-0.2)
all beta results at z~7 from different groups are in excellent agreement. The
mean beta we measure for faint (-18 mag: 0.1L*(z=3)) z~4, z~5, z~6, and z~7
galaxies is -2.03+/-0.03+/-0.06 (random and systematic errors),
-2.14+/-0.06+/-0.06, -2.24+/-0.11+/-0.08, and -2.30+/-0.18+/-0.13,
respectively. Our new beta values are redder than we have reported in the past,
but bluer than other recent results. Our previously reported trend of bluer
beta's at lower luminosities is confirmed, as is the evolution to bluer beta's
at high redshifts. beta appears to show only a mild luminosity dependence
faintward of M(UV,AB) ~ -19 mag, suggesting that the mean beta asymptotes to ~
-2.2 to -2.4 for faint z>~4 galaxies. At z~7, the observed beta's suggest
non-zero, but low dust extinction, and they agree well with values predicted in
cosmological hydrodynamical simulations.


title:
Indications of a sub-linear and non-universal Kennicutt-Schmidt
  relationship

abstract:
  We estimate the parameters of the Kennicutt-Schmidt (KS) relationship,
linking the star formation rate (Sigma_SFR) to the molecular gas surface
density (Sigma_mol), in the STING sample of nearby disk galaxies using a
hierarchical Bayesian method. This method rigorously treats measurement
uncertainties, and provides accurate parameter estimates for both individual
galaxies and the entire population. Assuming standard conversion factors to
estimate Sigma_SFR and Sigma_mol from the observations, we find that the KS
parameters vary between galaxies, indicating that no universal relationship
holds for all galaxies. The KS slope of the whole population is 0.76, with the
2sigma range extending from 0.58 to 0.94. These results imply that the
molecular gas depletion time is not constant, but varies from galaxy to galaxy,
and increases with the molecular gas surface density. Therefore, other galactic
properties besides just Sigma_mol affect Sigma_SFR, such as the gas fraction or
stellar mass. The non-universality of the KS relationship indicates that a
comprehensive theory of star formation must take into account additional
physical processes that may vary from galaxy to galaxy.


title: Multicritical behavior in models with two competing order parameters

abstract:
  We employ the nonperturbative functional Renormalization Group to study
models with an O(N_1)+O(N_2) symmetry. Here, different fixed points exist in
three dimensions, corresponding to bicritical and tetracritical behavior
induced by the competition of two order parameters. We discuss the critical
behavior of the symmetry-enhanced isotropic, the decoupled and the biconical
fixed point, and analyze their stability in the N_1, N_2 plane. We study the
fate of non-trivial fixed points during the transition from three to four
dimensions, finding evidence for a triviality problem for coupled two-scalar
models in high-energy physics. We also point out the possibility of
non-canonical critical exponents at semi-Gaussian fixed points and show the
emergence of Goldstone modes from discrete symmetries.


title:
Real-space density functional theory on graphical processing units:
  computational approach and comparison to Gaussian basis set methods

abstract:
  We discuss the application of graphical processing units (GPUs) to accelerate
real-space density functional theory (DFT) calculations. To make our
implementation efficient, we have developed a scheme to expose the data
parallelism available in the DFT approach; this is applied to the different
procedures required for a real-space DFT calculation. We present results for
current-generation GPUs from AMD and Nvidia, which show that our scheme,
implemented in the free code Octopus, can reach a sustained performance of up
to 90 GFlops for a single GPU, representing a significant speed-up when
compared to the CPU version of the code. Moreover, for some systems our
implementation can outperform a GPU Gaussian basis set code, showing that the
real-space approach is a competitive alternative for DFT simulations on GPUs.


title:
Simulations of supermassive black hole growth in high-redshift disk
  galaxies

abstract:
  Observations suggest that a large fraction of black hole growth occurs in
normal star-forming disk galaxies. Here we describe simulations of black hole
accretion in isolated disk galaxies with sufficient resolution (~5 pc) to track
the formation of giant molecular clouds that feed the black hole. Black holes
in z=2 gas-rich disks (fgas=50%) occasionally undergo ~10 Myr episodes of
Eddington-limited accretion driven by stochastic collisions with massive, dense
clouds. We predict that these gas-rich disks host weak AGNs 1/4 of the time,
and moderate/strong AGNs 10% of the time. Averaged over 100 Myr timescales and
the full distribution of accretion rates, the black holes grow at a few per
cent of the Eddington limit -- sufficient to match observations and keep the
galaxies on the MBH-Mbulge relation. This suggests that dense cloud accretion
in isolated z=2 disks could dominate cosmic black hole growth. In z=0 disks
with fgas=10%, Eddington-limited growth is extremely rare because typical gas
clouds are smaller and more susceptible to disruption by AGN feedback. This
results in an average black hole growth rate in high-fgas galaxies that is up
to 1000 times higher than that in low-fgas galaxies. In all our simulations,
accretion shows variability by factors of 10^4 on a variety of time scales,
with variability at 1 Myr scales driven by the structure of the interstellar
medium.


title: The structure of cosmic voids in a LCDM Universe

abstract:
  Eulerian cosmological codes are especially suited to properly describe the
low density regions. This property makes this class of codes excellent tools to
study the formation and evolution of cosmic voids. Following such ideas, we
present the results of an Eulerian adaptive mesh refinement (AMR)
hydrodynamical and N-body simulation, that contrary to the common practice, has
been designed to refine the computational grid in the underdense regions of the
simulated volume. Thus, the void regions are better described due to the
combined effect of the Eulerian character of the numerical technique and the
use of high numerical resolution from the AMR approach. To analyse the outcome
of this simulation, we have constructed a new void finder optimally suited to
find the hierarchy of voids in AMR simulations. The algorithm identifies voids
starting from the cells with least density and highest velocity divergence and
then expanding the underdense volume until reaching the void walls, defined
from the steepness of the density gradient. At redshift z=0, in a cosmological
box of comoving side length 100 Mpc/h, we identify hundreds of voids with sizes
up to 17 Mpc/h and typical density contrast of -0.8, which show a complex
morphology and an intricate hierarchy of nested structures. The analysis of
their mass density profile leads to the conclusion that a universal density
profile can be applied to voids of any size, density, morphology and redshift.


title: Mild-split SUSY with flavor

abstract:
  In the framework of a gauge mediated quiver-like model, the standard model
flavor texture can be naturally generated. The model - like the MSSM - has
furthermore a region in parameter space where the lightest Higgs mass is fed by
heavy stop loops, which in turn sets the average squark mass scale near 10-20
TeV. We perform a careful flavor analysis to check whether this type of
mild-split SUSY passes all flavor constraints as easily as envisioned in the
original type of split SUSY. Interestingly, it turns out to be on the border of
several constraints, in particular, the branching ratio of mu -> e gamma and,
if order one complex phases are assumed, also epsilon_K neutron and electron
EDM. Furthermore, we consider unification as well as dark matter candidates,
especially the gravitino. Finally, we provide a closed-form formula for the
soft masses of matter in arbitrary representations of any of the gauge groups
in a generic quiver-like model with a general messenger sector.


title:
Anomalous domain wall velocity and Walker breakdown in hybrid systems
  with anisotropic exchange

abstract:
  It has recently been proposed that spin-transfer torques in magnetic systems
with anisotropic exchange can be strongly enhanced, reducing the characteristic
current density with up to four orders of magnitude compared to conventional
setups. Motivated by this, we analytically solve the equations of motion in a
collective-coordinate framework for this type of anisotropic exchange system,
to investigate the domain wall dynamics in detail. In particular, we obtain
analytical expressions for the maximum attainable domain wall velocity of such
a setup and also for the occurrence of Walker breakdown. Surprisingly, we find
that, in contrast to the standard case with domain wall motion driven by the
nonadiabatic torque, the maximum velocity obtained via the anisotropic exchange
torque is completely independent of the nonadiabaticity parameter beta, in
spite of the torque itself being very large for small beta. Moreover, the
Walker breakdown threshold has an opposite dependence on beta in these two
cases; i.e., for the anisotropic exchange torque scenario, the threshold value
decreases monotonically with beta. These findings are of importance to any
practical application of the proposed giant spin-transfer torque in anisotropic
exchange systems.


title: Supersymmetric Renyi Entropy

abstract:
  We consider 3d N>= 2 superconformal field theories on a branched covering of
a three-sphere. The Renyi entropy of a CFT is given by the partition function
on this space, but conical singularities break the supersymmetry preserved in
the bulk. We turn on a compensating R-symmetry gauge field and compute the
partition function using localization. We define a supersymmetric observable,
called the super Renyi entropy, parametrized by a real number q. We show that
the super Renyi entropy is duality invariant and reduces to entanglement
entropy in the q -> 1 limit. We provide some examples.


title: Dynamical Dark Matter and the Positron Excess in Light of AMS

abstract:
  The AMS-02 experiment has recently released data which confirms a rise in the
cosmic-ray positron fraction as a function of energy up to approximately 350
GeV. Over the past decade, attempts to interpret this positron excess in terms
of dark-matter decays have become increasingly complex and have led to a number
of general expectations about the decaying dark-matter particles: such
particles cannot undergo simple two-body decays to leptons, for example, and
they must have rather heavy TeV-scale masses. In this paper, by contrast, we
show that Dynamical Dark Matter (DDM) can not only match existing AMS-02 data
on the positron excess, but also accomplish this feat with significantly
lighter dark-matter constituents undergoing simple two-body decays to leptons.
Moreover, we demonstrate that this can be done without running afoul of
numerous other competing constraints from FERMI and Planck on decaying dark
matter. Finally, we demonstrate that the Dynamical Dark Matter framework makes
a fairly robust prediction that the positron fraction should level off and then
remain roughly constant out to approximately 1 TeV, without experiencing any
sharp downturns. Indeed, if we interpret the positron excess in terms of
decaying dark matter, we find that the existence of a plateau in the positron
fraction at energies less than 1 TeV may be taken as a "smoking gun" of
Dynamical Dark Matter.


title: Large N Volume Independence and an Emergent Fermionic Symmetry

abstract:
  Large-N volume independence in circle-compactified QCD with N_f \geq 1
adjoint Weyl fermions implies the absence of any phase transitions as the
radius is dialed to arbitrarily small values. This class of theories are
believed to possess a Hagedorn density of hadronic states. It turns out that
these properties are in apparent tension with each other, because a Hagedorn
density of states typically implies a phase transition at some finite radius.
This tension is resolved if there are degeneracies between the spectra of
bosonic and fermionic states, as happens in the N_f=1 supersymmetric case.
Resolution of the tension for N_f>1 then suggests the emergence of a fermionic
symmetry at large N, where there is no supersymmetry. We can escape the
Coleman-Mandula theorem since the N=\infty theory is free, with a trivial
S-matrix. We show an example of such a spectral degeneracy in a
non-supersymmetric toy example which has a Hagedorn spectrum.


title: On Ghost-free Supersymmetric Galileons

abstract:
  We present consistent supersymmetric theories invariant under the
generalization of the Galilean shift symmetry to ${\cal{N}}=1$ superspace.
These theories are constructed via the decoupling limit of certain
non-minimally derivative coupled supergravities, thus they correspond to the
supersymmetrization of the so-called covariant Galileon. Specifically, these
theories are constructed in the linearized ${\cal{N}}=1$ new-minimal
supergravity set-up where the chiral supermultiplet is minimally coupled to
gravity via the standard R-current contact term, and, at the same time,
non-minimally derivatively coupled to the Einstein superfield.


title: Scattering in Three Dimensions from Rational Maps

abstract:
  The complete tree-level S-matrix of four dimensional ${\cal N}=4$ super
Yang-Mills and ${\cal N} = 8$ supergravity has compact forms as integrals over
the moduli space of certain rational maps. In this note we derive formulas for
amplitudes in three dimensions by using the fact that when amplitudes are
dressed with proper wave functions dimensional reduction becomes
straightforward. This procedure leads to formulas in terms of rational maps for
three dimensional maximally supersymmetric Yang-Mills and gravity theories. The
integrand of the new formulas contains three basic structures:
Parke-Taylor-like factors, Vandermonde determinants and resultants. Integrating
out some of the Grassmann directions produces formulas for theories with less
than maximal supersymmetry, which exposes yet a fourth kind of structure.
Combining all four basic structures we start a search for consistent S-matrices
in three dimensions. Very nicely, the most natural ones are those corresponding
to ABJM and BLG theories. We also make a connection between the power of a
resultant in the integrand, representations of the Poincar\'e group, infrared
behavior and conformality of a theory. Extensions to other theories in three
dimensions and to arbitrary dimensions are also discussed.


title:
Explaining Phenomenologically Observed Space-time Flatness Requires New
  Fundamental Scale Physics

abstract:
  The phenomenologically observed flatness - or near flatness - of spacetime
cannot be understood as emerging from continuum Planck (or sub-Planck) scales
using known physics. Using dimensional arguments it is demonstrated that any
immaginable action will lead to Christoffel symbols that are chaotic. We put
forward new physics in the form of fundamental fields that spontaneously break
translational invariance. Using these new fields as coordinates we define the
metric in such a way that the Riemann tensor vanishes identically as a Bianchi
identity. Hence the new fundamental fields define a flat space. General
relativity with curvature is recovered as an effective theory at larger scales
at which crystal defects in the form of disclinations come into play as the
sources of curvature.


title: The Sterile Neutrino Field and Late Time Acceleration

abstract:
  We show that when the neutrino minimal standard model ($\nu MSM$) with a
light sterile neutrino has a long range interaction between the neutrino vacuum
charge density and a dark U(1) gauge potential, late time acceleration is
dynamically realized. Moreover, the relation between the scale of dark energy,
the weak and Planck masses derived by Arkani-Hamed et. al
\cite{ArkaniHamed:2000tc} that addresses the coincidence problem arises
naturally in this model. Assuming that the cosmological constant is zero by
some as yet known mechanism, the only fine tuning in our model is the mass of
the sterile neutrino. We show that perturbations of the vector fields are
oscillatory and hence, there are no instabilities.


title: Random sequential adsorption of tetramers

abstract:
  Adsorption of tetramer built of four identical spheres was studied
numerically using the Random Sequential Adsorption (RSA) algorithm. Tetramers
were adsorbed on a two dimensional, flat and homogeneous surface. Two different
models of the adsorbate were investigated: a rhomboid and a square one; monomer
centres were put on vertices of rhomboids and squares, respectively. Numerical
simulations allow to establish the maximal random coverage ratio as well as the
Available Surface Function (ASF), which is crucial for determining kinetics of
the adsorption process. These results were compared with data obtained
experimentally for KfrA plasmid adsorption. Additionally, the density
autocorrelation function was measured.


title: Sputtered TiN films for superconducting coplanar waveguide resonators

abstract:
  We present a systematic study of the properties of TiN films by varying the
deposition conditions in an ultra-high-vacuum reactive magnetron sputtering
chamber. By increasing the deposition pressure from 2 to 9 mTorr while keeping
a nearly stoichiometric composition of Ti(1-x)N(x) (x=0.5), the film
resistivity increases, the dominant crystal orientation changes from (100) to
(111), grain boundaries become clearer, and the strong compressive strain
changes to weak tensile strain. The TiN films absorb a high concentration of
contaminants including hydrogen, carbon, and oxygen when they are exposed to
air after deposition. With the target-substrate distance set to 88 mm the
contaminant levels increase from ~0.1% to ~10% as the pressure is increased
from 2 to 9 mTorr. The contaminant concentrations also correlate with in-plane
distance from the center of the substrate and increase by roughly two orders of
magnitude as the target-substrate distance is increased from 88 mm to 266 mm.
These contaminants are found to strongly influence the properties of TiN films.
For instance, the resistivity of stoichiometric films increases by around a
factor of 5 as the oxygen content increases from 0.1% to 11%. These results
suggest that the sputtered TiN particle energy is critical in determining the
TiN film properties, and that it is important to control this energy to obtain
high-quality TiN films. Superconducting coplanar waveguide resonators made from
a series of nearly stoichiometric films grown at pressures from 2 mTorr to 7
mTorr show an increase in intrinsic quality factor from ~10^4 to ~10^6 as the
magnitude of the compressive strain decreases from nearly 3800 MPa to
approximately 150 MPa and the oxygen content increases from 0.1% to 8%. The
films with a higher oxygen content exhibit lower loss, but the nonuniformity of
the oxygen incorporation hinders the use of sputtered TiN in larger circuits.


title: Optimization of Clustering for Clustering-based Image Denoising

abstract:
  In this paper, the problem of de-noising of an image contaminated with
additive white Gaussian noise (AWGN) is studied. This subject has been
continued to be an open problem in signal processing for more than 50 years. In
the present paper, we suggest a method based on global clustering of image
constructing blocks. Noting that the type of clustering plays an important role
in clustering-based de-noising methods, we address two questions about the
clustering. First, which parts of data should be considered for clustering?
Second, what data clustering method is suitable for de-noising? Clustering is
exploited to learn an over complete dictionary. By obtaining sparse
decomposition of the noisy image blocks in terms of the dictionary atoms, the
de-noised version is achieved. Experimental results show that our dictionary
learning framework outperforms traditional dictionary learning methods such as
K-SVD.


title:
Determinant quantum Monte Carlo study of the two-dimensional single-band
  Hubbard-Holstein model

abstract:
  We have performed numerical studies of the Hubbard-Holstein model in two
dimensions using determinant quantum Monte Carlo (DQMC). Here we present
details of the method, emphasizing the treatment of the lattice degrees of
freedom, and then study the filling and behavior of the fermion sign as a
function of model parameters. We find a region of parameter space with large
Holstein coupling where the fermion sign recovers despite large values of the
Hubbard interaction. This indicates that studies of correlated polarons at
finite carrier concentrations are likely accessible to DQMC simulations. We
then restrict ourselves to the half-filled model and examine the evolution of
the antiferromagnetic structure factor, other metrics for antiferromagnetic and
charge-density-wave order, and energetics of the electronic and lattice degrees
of freedom as a function of electron-phonon coupling. From this we find further
evidence for a competition between charge-density-wave and antiferromagnetic
order at half-filling.