title: General self-tuning solutions and no-go theorem

abstract:
  We consider brane world models with one extra dimension. In the bulk there is
in addition to gravity a three form gauge potential or equivalently a scalar
(by generalisation of electric magnetic duality). We find classical solutions
for which the 4d effective cosmological constant is adjusted by choice of
integration constants. No go theorems for such self-tuning mechanism are
circumvented by unorthodox Lagrangians for the three form respectively the
scalar. It is argued that the corresponding effective 4d theory always includes
tachyonic Kaluza-Klein excitations or ghosts. Known no go theorems are extended
to a general class of models with unorthodox Lagrangians.


title: Small flow rate can supply inwardly migrating shortest-period planets

abstract:
  The number of exoplanets found with periods as short as one day and less was
surprising given how fast these planets had been expected to migrate into the
star due to the tides raised on the star by planets at such close distances. It
has been seen as improbable that we would find planets in such a small final
fraction of their lives. The favored solution has been that the tidal
dissipation is much weaker than expected, which would mean that the final
infall would be a larger fraction of the planets' life. We find no reason to
exclude the explanation that a small number of planets are continuously sent
migrating inwards such that these planets indeed are in the last fraction of
their lives. Following the observation that the distribution of medium planets
disfavors tidal dissipation being significantly weaker than has been found from
observations of binary stars, we now show that the numbers of planets in such a
"flow" of excess planets migrating inwards is low enough that even depletion of
the three-day pileup is a plausible source. Then the shortest period occurrence
distribution would be shaped by planets continuously being sent into the star,
which may explain the depletion of the pileup in the Kepler field relative to
the solar neighborhood (Howard et al. 2012, hereafter H12). Because Kepler
observes above the galactic plane, H12 suggested the Kepler field may include
an older population of stars. The tidal dissipation strength in stars due to
giant planets may be not greatly weaker than it is in binary stars.


title: Topological Insulators Avoid the Parity Anomaly

abstract:
  The surface of a 3+1d topological insulator hosts an odd number of gapless
Dirac fermions when charge conjugation and time-reversal symmetries are
preserved. Viewed as a purely 2+1d system, this surface theory would
necessarily explicitly break parity and time-reversal when coupled to a
fluctuating gauge field. Here we explain why such a state can exist on the
boundary of a 3+1d system without breaking these symmetries, even if the number
of boundary components is odd. This is accomplished from two complementary
perspectives: topological quantization conditions and regularization. We first
discuss the conditions under which (continuous) large gauge transformations may
exist when the theory lives on a boundary of a higher-dimensional spacetime.
Next, we show how the higher-dimensional bulk theory is essential in providing
a parity-invariant regularization of the theory living on the lower-dimensional
boundary or defect.


title:
Convex conditions for robust stabilization of uncertain switched systems
  with guaranteed minimum dwell-time

abstract: Paper withdrawn by the author


title:
Detection Prospects for GeV Neutrinos from Collisionally Heated
  Gamma-ray Bursts with IceCube/DeepCore

abstract:
  Jet heating via nuclear collisions may be the main mechanism for gamma-ray
burst (GRB) emission. Besides producing the observed gamma-rays, collisional
heating must generate 10-100 GeV neutrinos, implying a close relation between
the neutrino and gamma-ray luminosities. We exploit this theoretical relation
to make predictions for possible GRB detections by IceCube+DeepCore. To
estimate the expected neutrino signal, we use the largest sample of bursts
observed by BATSE in 1991-2000. A GRB neutrino could have been detected if
IceCube+DeepCore operated at that time. Detection of 10-100 GeV neutrinos would
have significant implications, shedding light on the composition of GRB jets
and their Lorentz factors. This could be an important target in designing
future upgrades of the IceCube+DeepCore observatory.


title: Complex Path Integrals and the Space of Theories

abstract:
  The Feynman Path Integral is extended in order to capture all solutions of a
quantum field theory. This is done via a choice of appropriate integration
cycles, parametrized by M in SL(2,C), i.e., the space of allowed integration
cycles is related to certain Dp-branes and their properties, which can be
further understood in terms of the "physical states" of another theory. We also
look into representations of the Feynman Path Integral in terms of a
Mellin-Barnes transform, bringing the singularity structure of the theory to
the foreground. This implies that, as a sum over paths, we should consider more
generic paths than just Brownian ones. Finally, we are able to study the Space
of Theories through our examples in terms of their Quantum Phases and
associated Stokes' Phenomena (wall-crossing).


title:
Controlling the group velocity of colliding atomic Bose-Einstein
  condensates with Feshbach resonances

abstract:
  We report on a proposal to change the group velocity of a small Bose Einstein
Condensate (BEC) upon collision with another BEC in analogy to slowing of light
passing through dispersive media. We make use of ultracold collisions near a
magnetic Feshbach resonance, which gives rise to a sharp variation in
scattering length with collision energy and thereby changes the group velocity.
A generalized Gross-Pitaveskii equation is derived for a small BEC moving
through a larger stationary BEC. We denote the two condensates by laser and
medium BEC, respectively, to highlight the analogy to a laser pulse travelling
through a medium. We derive an expression for the group velocity in a
homogeneous medium as well as for the difference in distance, $\delta$, covered
by the laser BEC in the presence and absence of a finite-sized medium BEC with
a Thomas-Fermi density distribution. For a medium and laser of the same
isotopic species, the shift $\delta$ has an upper bound of twice the
Thomas-Fermi radius of the medium. For typical narrow Feshbach resonances and a
medium with number density $10^{15}$ cm$^{-3}$ up to 85% of the upper bound can
be achieved, making the effect experimentally observable. We also derive
constraints on the experimental realization of our proposal.


title:
Magnetic flux tuning of Fano-Kondo interplay in a parallel double
  quantum dot system

abstract:
  We investigate the Fano-Kondo interplay in an Aharonov-Bohm ring with an
embedded non-interacting quantum dot and a Coulomb interacting quantum dot.
Using a slave-boson mean-field approximation we diagonalize the Hamiltonian via
scattering matrix theory, and derive the conductance in the form of a Fano
expression, which depends on the mean field parameters. We predict that in the
Kondo regime the magnetic field leads to a gapped energy level spectrum due to
hybridisation of the non-interacting QD state and the Kondo state, and can
quantum-mechanically alter the electron's path preference. We demonstrate that
an abrupt symmetry change in the Fano resonance, as seen experimentally, could
be a consequence of an underlying Kondo channel.


title: Subphotospheric Neutrinos from Gamma-Ray Bursts: The Role of Neutrons

abstract:
  Relativistic outflows with neutrons inevitably lead to inelastic collisions,
and resulting subphotospheric gamma rays may explain prompt emission of
gamma-ray bursts. In this model, hadronuclear, quasithermal neutrinos in the
10-100 GeV range should be generated, and they may even have a high-energy tail
by neutron-proton-converter or shock acceleration mechanisms. We demonstrate
the importance of dedicated searches with DeepCore+IceCube, though such
analyses have not been performed. Successful detections enable us to
discriminate among prompt emission mechanisms, probe the jet composition, and
see roles of relativistic neutrons as well as effects of cosmic-ray
acceleration.


title: Fusion Procedure for Cyclotomic Hecke Algebras

abstract:
  A complete system of primitive pairwise orthogonal idempotents for cyclotomic
Hecke algebras is constructed by consecutive evaluations of a rational function
in several variables on quantum contents of multi-tableaux. This function is a
product of two terms, one of which depends only on the shape of the
multi-tableau and is proportional to the inverse of the corresponding Schur
element.


title:
Equalities and inequalities for Hermitian solutions and Hermitian
  definite solutions of the two matrix equations $AX = B$ and $AXA^* = B$

abstract:
  This paper studies algebraic properties of Hermitian solutions and Hermitian
definite solutions of the two types of matrix equation $AX = B$ and $AXA^* =
B$. We first establish a variety of rank and inertia formulas for calculating
the maximal and minimal ranks and inertias of Hermitian solutions and Hermitian
definite solutions of the matrix equations $AX = B$ and $AXA^* = B$, and then
use them to characterize many qualities and inequalities for Hermitian
solutions and Hermitian definite solutions of the two matrix equations and
their variations.


title: Calculating the two-pion decay and mixing of neutral K mesons

abstract:
  The recent calculation of the complex isospin-two decay amplitude A_2 with
physical kinematics is presented together with exploratory calculations of the
isospin-zero decay amplitude A_0. Prospects for accurate calculation of A_0 as
well as the mass difference between the K_L and K_S mesons are discussed.


title:
Hypothesis Testing in High-Dimensional Regression under the Gaussian
  Random Design Model: Asymptotic Theory

abstract:
  We consider linear regression in the high-dimensional regime where the number
of observations $n$ is smaller than the number of parameters $p$. A very
successful approach in this setting uses $\ell_1$-penalized least squares
(a.k.a. the Lasso) to search for a subset of $s_0< n$ parameters that best
explain the data, while setting the other parameters to zero. Considerable
amount of work has been devoted to characterizing the estimation and model
selection problems within this approach.
  In this paper we consider instead the fundamental, but far less understood,
question of \emph{statistical significance}. More precisely, we address the
problem of computing p-values for single regression coefficients.
  On one hand, we develop a general upper bound on the minimax power of tests
with a given significance level. On the other, we prove that this upper bound
is (nearly) achievable through a practical procedure in the case of random
design matrices with independent entries. Our approach is based on a debiasing
of the Lasso estimator. The analysis builds on a rigorous characterization of
the asymptotic distribution of the Lasso estimator and its debiased version.
Our result holds for optimal sample size, i.e., when $n$ is at least on the
order of $s_0 \log(p/s_0)$.
  We generalize our approach to random design matrices with i.i.d. Gaussian
rows $x_i\sim N(0,\Sigma)$. In this case we prove that a similar distributional
characterization (termed `standard distributional limit') holds for $n$ much
larger than $s_0(\log p)^2$.
  Finally, we show that for optimal sample size, $n$ being at least of order
$s_0 \log(p/s_0)$, the standard distributional limit for general Gaussian
designs can be derived from the replica heuristics in statistical physics.

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


title: Graphene plasmonics

abstract:
  Two rich and vibrant fields of investigation, graphene physics and
plasmonics, strongly overlap. Not only does graphene possess intrinsic plasmons
that are tunable and adjustable, but a combination of graphene with noble-metal
nanostructures promises a variety of exciting applications for conventional
plasmonics. The versatility of graphene means that graphene-based plasmonics
may enable the manufacture of novel optical devices working in different
frequency ranges, from terahertz to the visible, with extremely high speed, low
driving voltage, low power consumption and compact sizes. Here we review the
field emerging at the intersection of graphene physics and plasmonics.


title:
HST/COS Spectra of Three QSOs That Probe The Circumgalactic Medium of a
  Single Spiral Galaxy: Evidence for Gas Recycling and Outflow

abstract:
  We have used the Cosmic Origins Spectrograph (COS) to obtain far-UV spectra
of three closely-spaced QSO sight lines that probe the circumgalactic medium
(CGM) of an edge-on spiral galaxy, ESO 157-49, at impact parameters of 74 and
93 kpc near its major axis and 172 kpc along its minor axis. H I Ly\alpha\
absorption is detected at the galaxy redshift in the spectra of all three QSOs,
and metal lines of Si III, Si IV, and C IV are detected along the two
major-axis sight lines. Photoionization models of these clouds suggest
metallicities close to the galaxy metallicity, cloud sizes of ~1 kpc, and gas
masses of ~10^4 solar masses. Given the high covering factor of these clouds,
ESO 157-49 could harbor ~2x10^9 solar masses of warm CGM gas. We detect no
metals in the sight line that probes the galaxy along its minor axis, but gas
at the galaxy metallicity would not have detectable metal absorption with
ionization conditions similar to the major-axis clouds. The kinematics of the
major-axis clouds favor these being portions of a "galactic fountain" of
recycled gas, while two of the three minor-axis clouds are constrained
geometrically to be outflowing gas.
  In addition, one of our QSO sight lines probes a second more distant spiral,
ESO 157-50, along its major axis at an impact parameter of 88 kpc. Strong H I
Ly\alpha\ and C IV absorption only are detected in the QSO spectrum at the
redshift of ESO 157-50.


title: Badly approximable points on planar curves and a problem of Davenport

abstract:
  Let C be two times continuously differentiable curve in R^2 with at least one
point at which the curvature is non-zero. For any i,j > 0 with i+j =1, let
Bad(i,j) denote the set of points (x,y) in R^2 for which max {||qx ||^{1/i},
||qy||^{1/j}} > c/q for all integers q >0. Here c = c(x,y) is a positive
constant. Our main result implies that any finite intersection of such sets
with C has full Hausdorff dimension. This provides a solution to a problem of
Davenport dating back to the sixties.


title:
The AGN dusty torus as a clumpy two-phase medium: radiative transfer
  modeling with SKIRT

abstract:
  We modeled the AGN dusty torus as a clumpy two-phase medium, with
high-density clumps embedded in a low-density interclump dust. To obtain
spectral energy distributions and images of the torus at different wavelengths,
we employed the 3D Monte Carlo radiative transfer code SKIRT. Apart from the
grid of two-phase models, we calculated the corresponding sets of clumps-only
models and models with a smooth dust distribution for comparison. We found that
the most striking feature of the two-phase model is that it might offer a
natural solution to the common issue reported in a number of papers -- the
observed excess of the near-infrared emission.


title:
Vortex ground state for small arrays of magnetic particles with dipole
  coupling

abstract:
  We show that a magnetic vortex is the ground state of an array of magnetic
particles shaped as a hexagonal fragment of a triangular lattice, even for an
small number of particles in the array $N \leq 100$. The vortex core appears
and the symmetry of the vortex state changes with the increase of the intrinsic
magnetic anisotropy of the particle $\beta$; the further increase of $\beta$
leads to the destruction of the vortex state. Such vortices can be present in
arrays as small in size as dozen of nanometers.


title: Matrix product states for quantum metrology

abstract:
  We demonstrate that the optimal states in lossy quantum interferometry may be
efficiently simulated using low rank matrix product states. We argue that this
should be expected in all realistic quantum metrological protocols with
uncorrelated noise and is related to the elusive nature of the Heisenberg
precision scaling in presence of decoherence.


title: Functional Magnetic Resonance Imaging: a study of malnourished rats

abstract:
  Malnutrition is a main public health problem in developing countries.
Incidence is increasing and the mortality rate is still high. Malnutrition can
leads mayor problems that can be irreversible if it is present before brain
development is completed. We used BOLD (blood oxygen level-dependent effect)
Functional Magnetic Resonance Imaging to investigate the regions of brain
activity in malnourished rats. The food competition method was applied to a rat
model to provoke malnutrition during lactation. The weight increase is delayed
even if there is plenty milk available. To localize those regions of activity
resulting from the trigeminal nerve stimulation, the vibrissae-barrel axis was
employed due to the functional and morphological correlation between the
vibrissae and the barrels. BOLD response changes caused by the trigeminal nerve
stimulation on brain activity of malnourished and control rats were obtained at
7T. Results showed a major neuronal activity in malnourished rats on regions
like cerebellum, somatosensorial cortex, hippocampus, and hypothalamus. This is
the first study in malnourished rats and illustrates BOLD activation in various
brain structures.


title:
Random coincidence of $2\nu2\beta$ decay events as a background source
  in bolometric $0\nu2\beta$ decay experiments

abstract:
  Two neutrino double $\beta$ decay can create irremovable background even in
high energy resolution detectors searching for neutrinoless double $\beta$
decay due to random coincidence of $2\nu2\beta$ events in case of poor time
resolution. Possibilities to suppress this background in cryogenic
scintillating bolometers are discussed. It is shown that the present bolometric
detector technologies enable to control this form of background at the level
required to explore the inverted hierarchy of the neutrino mass pattern,
including the case of bolometers searching for the neutrinoless double $\beta$
decay of $^{100}$Mo, which is characterized by a relatively short two neutrino
double $\beta$ decay half-life.


title: Regularity and algebraic properties of certain lattice ideals

abstract:
  We study the regularity and the algebraic properties of certain lattice
ideals. We establish a map I --> I\~ between the family of graded lattice
ideals in an N-graded polynomial ring over a field K and the family of graded
lattice ideals in a polynomial ring with the standard grading. This map is
shown to preserve the complete intersection property and the regularity of I
but not the degree. We relate the Hilbert series and the generators of I and
I\~. If dim(I)=1, we relate the degrees of I and I\~. It is shown that the
regularity of certain lattice ideals is additive in a certain sense. Then, we
give some applications. For finite fields, we give a formula for the regularity
of the vanishing ideal of a degenerate torus in terms of the Frobenius number
of a semigroup. We construct vanishing ideals, over finite fields, with
prescribed regularity and degree of a certain type. Let X be a subset of a
projective space over a field K. It is shown that the vanishing ideal of X is a
lattice ideal of dimension 1 if and only if X is a finite subgroup of a
projective torus. For finite fields, it is shown that X is a subgroup of a
projective torus if and only if X is parameterized by monomials. We express the
regularity of the vanishing ideal over a bipartie graph in terms of the
regularities of the vanishing ideals of the blocks of the graph.


title: A new proof of Lucas' Theorem

abstract: We give a new proof of Lucas' Theorem in elementary number theory.


title:
Phase transition in a coevolving network of conformist and contrarian
  voters

abstract:
  In the coevolving voter model, each voter has one of two diametrically
opposite opinions, and a voter encountering a neighbor with the opposite
opinion may either adopt it or rewire the connection to another randomly chosen
voter sharing the same opinion. As we smoothly change the relative frequency of
rewiring compared to that of adoption, there occurs a phase transition between
an active phase and a frozen phase. By performing extensive Monte Carlo
calculations, we show that the phase transition is characterized by critical
exponents {\beta}=0.54(1) and {\nu} =1.5(1), which differ from the existing
mean-field-type prediction. We furthermore extend the model by introducing a
contrarian type that tries to have neighbors with the opposite opinion, and
show that the critical behavior still belongs to the same universality class
irrespective of such contrarians' fraction.


title: Estimating Norms of Commutators

abstract:
  We find estimates on the norms commutators of the form [f(x), y] in terms of
the norm of [x, y] assuming that x and y are contractions in a C*-algebra A,
with x normal and with spectrum within the domain of f. In particular we
discuss [x^2, y] and [x^(1/2), y] for 0 <=, x <=, 1. For larger values of
\delta = \|[x; y]\| we can rigorous calculate the best possible upper bound
\|[f(x), y]\| for many f. In other cases we have conducted numerical
experiments that strongly suggest that we have in many cases found the correct
formula for the best upper bound.


title:
Toward a real synthesis of quantum and relativity theories: experimental
  evidence for absolute simultaneity

abstract:
  We have demonstrated spatially-discontinuous jumps of electrons at a distance
as long as about 1cm. The effect occurs in a modified integer quantum Hall
system consisted of a great number of extended Laughlin-Halperin-type states.
Our observations directly contradict the no-aether Einstein's interpretation of
special relativity together with the Minkowski's model of spacetime. However
they are consistent with the aether-related Lorentz-Poincare's interpretation
that allows absolute simultaneity. We thus strongly challenge the fundamental
status of Lorentz invariance and hence break the basic argument against de
Broglie-Bohm realistic quantum theory. We argue that both de Broglie-Bohm and
Lorentz-Poincare theories are capable of providing a real synthesis of quantum
and relativity theories. The synthesis is of such kind that quantum theory
appears the most fundamental physical theory for which relativity is only a
limiting case. In accordance with this hierarchy, quantum theory naturally
resolves the problem of aether in Lorentz-Poincare's relativity. The aether
could be a deeper Bohm-type undivided quantum pre-space, the relevance of which
directly follows from our observations.


title: Why is the top quark much heavier than other fermions?

abstract:
  The recent ATLAS and CMS experiments show the first observations of a new
particle in the search for the Standard Model Higgs boson at the LHC. We
revisit the theoretical inconsistency of the fundamental high-energy cutoff
with the parity-violating gauge symmetry of local quantum field theory for the
standard model. This inconsistency suggests high-dimensional operators of
fermion interactions, which are attributed to the quantum gravity. In this
letter, recalling the minimal dynamical symmetry-breaking mechanism, we show
that it is energetically favorable for the top quark to acquire its mass via
spontaneous symmetry breaking, whereas other fermions acquire their masses via
explicit symmetry breaking.


title: A Tonnetz Model for pentachords

abstract:
  This article deals with the construction of surfaces that are suitable for
representing pentachords or 5-pitch segments that are in the same $T/I$ class.
It is a generalization of the well known \"Ottingen-Riemann torus for triads of
neo-Riemannian theories. Two pentachords are near if they differ by a
particular set of contextual inversions and the whole contextual group of
inversions produces a Tiling (Tessellation) by pentagons on the surfaces. A
description of the surfaces as coverings of a particular Tiling is given in the
twelve-tone enharmonic scale case.


title:
Entanglement between nitrogen vacancy spins in diamond controlled by a
  nanomechanical resonator

abstract:
  We suggest a new type of nano-electromechanical resonator, the functionality
of which is based on a magnetic field induced deflection of an appropriate
cantilever that oscillates between nitrogen vacancy (NV) spins in daimond.
Specifically, we consider a Si(100) cantilever coated with a thin magnetic Ni
film. Magnetoelastic stress and magnetic-field induced torque are utilized to
induce a controlled cantilever deflection. It is shown that, depending on the
value of the system parameters, the induced asymmetry of the cantilever
deflection substantially modifies the characteristics of the system. In
particular, the coupling strength between the NV spins and the degree of
entanglement can be controlled through magnetoelastic stress and magnetic-field
induced torque effects. Our theoretical proposal can be implemented
experimentally with the potential of increasing several times the coupling
strength between the NV spins as compared to the maximal coupling strength
reported before in P. Rabl, et al. Phys. Rev. B 79, 041302(R) (2009).


title: Growth of Sha in towers for isogenous curves

abstract:
  We study the growth of the Tate-Shafarevich and p-infinity Selmer groups for
isogenous abelian varieties in towers of number fields, with an emphasis on
elliptic curves. The growth types are usually exponential, as in the setting of
`positive mu-invariant' in Iwasawa theory of elliptic curves. The towers we
consider are p-adic and l-adic Lie extensions for l<>p, in particular
cyclotomic and other Z_l-extensions.


title:
Design Pattern-Based Extension of Class Hierarchies to Support Runtime
  Invariant Checks

abstract:
  We present a technique for automatically weaving structural invariant checks
into an existing collection of classes. Using variations on existing design
patterns, we use a concise specification to generate from this collection a new
set of classes that implement the interfaces of the originals, but with the
addition of user-specified class invariant checks. Our work is notable in the
scarcity of assumptions made. Unlike previous design pattern approaches to this
problem, our technique requires no modification of the original source code,
relies only on single inheritance, and does not require that the attributes
used in the checks be publicly visible. We are able to instrument a wide
variety of class hierarchies, including those with pure interfaces, abstract
classes and classes with type parameters. We have implemented the construction
as an Eclipse plug-in for Java development.


title: How to Fold a Manifold

abstract:
  Techniques for constructing codimension 2 embeddings and immersions of the 2
and 3-fold branched covers of the 3 and 4-dimensional spheres are presented.
These covers are in braided form, and it is in this sense that they are folded.
More precisely the composition of the embedding (or immersion) and the
canonical projection induces the branched covering map. In the case of the
3-sphere, the branch locus is a knotted or linked curve in space, the 2-fold
branched cover always embeds, and the 3-fold branch cover might be immersed. In
the case of the 4-sphere, the branch locus is a knotted or linked orientable
surface (surface knot or link), and the 2-fold branched cover is always
embedded. We give an explicit embedding of the 3-fold branched cover of the
4-sphere when the branch set is the spun trefoil.


title: Turbulent momentum pinch of diamagnetic flows in a tokamak

abstract:
  The ion toroidal rotation in a tokamak consists of an $E\times B$ flow due to
the radial electric field and a diamagnetic flow due to the radial pressure
gradient. The turbulent pinch of toroidal angular momentum due to the Coriolis
force studied in previous work is only applicable to the $E\times B$ flow. In
this Letter, the momentum pinch for the rotation generated by the radial
pressure gradient is calculated and is compared with the Coriolis pinch. This
distinction is important for subsonic flows or the flow in the pedestal where
the two types of flows are similar in size and opposite in direction. In the
edge, the different pinches due to the opposite rotations can result in
intrinsic momentum transport that gives significant rotation peaking.


title: The Bulge of M31

abstract:
  Bulges are not just elliptical subgalaxies situated in the centers of large
spirals. It might seem that way from their ages and chemistry, but bulge
kinematics have been known to be different since the first long slit spectra
were obtained. M31 presents the best opportunity to investigate all the issues
of the stellar populations of bulges. This review collects the array of probing
data that has been accumulated in the last decade. But the intriguing question
`how did it form like this ?' remains.


title: Ion acceleration from laser-driven electrostatic shocks

abstract:
  Multi-dimensional particle-in-cell simulations are used to study the
generation of electrostatic shocks in plasma and the reflection of background
ions to produce high-quality and high-energy ion beams. Electrostatic shocks
are driven by the interaction of two plasmas with different density and/or
relative drift velocity. The energy and number of ions reflected by the shock
increase with increasing density ratio and relative drift velocity between the
two interacting plasmas. It is shown that the interaction of intense lasers
with tailored near-critical density plasmas allows for the efficient heating of
the plasma electrons and steepening of the plasma profile at the critical
density interface, leading to the generation of high-velocity shock structures
and high-energy ion beams. Our results indicate that high-quality 200 MeV
shock-accelerated ion beams required for medical applications may be obtained
with current laser systems.


title:
Report from the Workshop on Molecular Spectroscopy in the Era of
  Far-Infrared Astronomy

abstract:
  A group of 72 members of the astrochemistry and spectroscopy communities
assembled at Emory University in October, 2012, to discuss the state-of-the art
in molecular laboratory spectroscopic techniques used to study molecules of
astrophysical interest, and highlight recent successes in laboratory efforts
that complement new astronomical observations. The format of the meeting
facilitated detailed discussion of the needs for collecting and interpreting
molecular spectroscopic information to support observational astrophysics in
the era of Far-IR astronomy. We present the findings and recommendations from
this workshop in this report. The participants in this workshop identified the
development of new laboratory capabilities that offer rapid, broadband,
high-resolution, high-sensitivity measurements of molecular spectra in the
frequency ranges that overlap with new observational facilities as the top
priority for far-infrared laboratory astrophysics initiatives over the next
5-10 years. An additional major need is the development of suitable analysis
tools for broadband molecular spectra from both the laboratory and space;
though such efforts should be conducted within the framework of larger
collaborative funding structures, rather than through single-PI efforts, so as
to provide tools that are generally applicable rather than highly specialized.
Additional efforts in theory, computation, and modeling that support these
goals are also important for advancing this field.


title: Innocent Bystanders: Carbon Stars from the Sloan Digital Sky Survey

abstract:
  Among stars showing carbon molecular bands (C stars), the main sequence
dwarfs, likely in post-mass transfer binaries, are numerically dominant in the
Galaxy. Via spectroscopic selection from the Sloan Digital Sky Survey, we
retrieve 1220 C stars, ~5 times more than previously known, including a wider
variety than past techniques such as color or grism selection have netted, and
additionally yielding 167 DQ white dwarfs. Of the C stars with proper motion
measurements, we identify 69% as clearly dwarfs (dCs), while ~7% are giants.
The dCs likely span absolute magnitudes M_i from ~6.5 to 10.5. "G-type" dC
stars with weak CN and relatively blue colors are probably the most massive dCs
still cool enough to show C_2 bands. We report Balmer emission in 22 dCs, none
of which are G-types. We find 8 new DA/dC stars in composite spectrum binaries,
quadrupling the total sample of these "smoking guns" for AGB binary mass
transfer. Eleven very red C stars with strong red CN bands appear to be
"N"-type AGB stars at large Galactocentric distances, one likely a new
discovery in the dIrr galaxy Leo A. Two such stars within 30arcmin of each
other may trace a previously unidentified dwarf galaxy or tidal stream at ~40
kpc. We explore the multiwavelength properties of the sample and report the
first X-ray detection of a dC star, which shows strong Balmer emission. Our own
spectroscopic survey additionally provides the dC surface density from a
complete sample of dwarfs limited by magnitude, color, and proper-motion.


title:
Theory and synthesis of bilayer graphene intercalated with ICl and IBr
  for low power device applications

abstract:
  Graphene intercalation materials are potentially promising for the
implementation of the ultra-low power, excitonic-condensate-based Bilayer
pseudoSpin Field-Effect Transistor (BiSFET) concept, as well as other novel
device concepts requiring a graphene interlayer dielectric. Using density
functional theory (DFT) we study the structural and electronic properties of
bilayer graphene intercalated with iodine monochloride (ICl) and iodine
monobromide (IBr). We determine the structural configuration of ICl and IBr
graphene intercalation compounds (GICs). We also conduct an in-depth
exploration of inter-layer electronic coupling, using \textit{ab initio}
calculations. The presence of intercalants dopes the graphene layer. It also
reduces, but does not eliminate, the electronic coupling between graphene
layers, which may enable BiSFET operation. In addition, we present experimental
results for ICl-GIC synthesis and characterization.


title: Strong and ratio asymptotics for Laguerre polynomials revisited

abstract:
  In this paper we consider the strong asymptotic behavior of Laguerre
polynomials in the complex plane. The leading behavior is well known from
Perron and Mehler-Heine formulas, but higher order coefficients, which are
important in the context of Krall-Laguerre or Laguerre-Sobolev-type orthogonal
polynomials, are notoriously difficult to compute. In this paper, we propose
the use of an alternative expansion, due to Buchholz, in terms of Bessel
functions of the first kind. The coefficients in this expansion can be obtained
in a straightforward way using symbolic computation. As an application, we
derive extra terms in the asymptotic expansion of ratios of Laguerre
polynomials in $C\[0,\infty)$.


title:
The Role of Lattice Coupling in Establishing Electronic and Magnetic
  Properties in Quasi-One-Dimensional Cuprates

abstract:
  High resolution resonant inelastic x-ray scattering has been performed to
reveal the role of lattice-coupling in a family of quasi-1D insulating
cuprates, Ca$_{2+5x}$Y$_{2-5x}$Cu$_5$O$_{10}$. Site-dependent low energy
excitations arising from progressive emissions of a 70 meV lattice vibrational
mode are resolved for the first time, providing a direct measurement of
electron-lattice coupling strength. We show that such electron-lattice coupling
causes doping-dependent distortions of the Cu-O-Cu bond angle, which sets the
intra-chain spin exchange interactions. Our results indicate that the lattice
degrees of freedom are fully integrated into the electronic behavior in low
dimensional systems.


title: Charged Higgs boson benchmarks in the CP-violating type-II 2HDM

abstract:
  We discuss prospects for discovering a charged Higgs boson in the
CP-violating type-II two-Higgs-doublet Model. In the light of recent LHC data,
we focus on the parameter space that survives experimental as well as the
theoretical constraints on the model. Once the phenomenological scenario is
set, we analyse the scope for the LHC to discover a charged Higgs in
association with the lightest neutral Higgs and a charged vector boson.


title: One-Round Multi-Party Communication Complexity of Distinguishing Sums

abstract:
  We consider an instance of the following problem: Parties P_1,..., P_k each
receive an input x_i, and a coordinator (distinct from each of these parties)
wishes to compute f(x_1,..., x_k) for some predicate f. We are interested in
one-round protocols where each party sends a single message to the coordinator;
there is no communication between the parties themselves. What is the minimum
communication complexity needed to compute f, possibly with bounded error?
  We prove tight bounds on the one-round communication complexity when f
corresponds to the promise problem of distinguishing sums (namely, determining
which of two possible values the {x_i} sum to) or the problem of determining
whether the {x_i} sum to a particular value. Similar problems were studied
previously by Nisan and in concurrent work by Viola. Our proofs rely on basic
theorems from additive combinatorics, but are otherwise elementary.


title:
A Gravitational Aharonov-Bohm Effect, and its Connection to Parametric
  Oscillators and Gravitational Radiation

abstract:
  A thought experiment is proposed to demonstrate the existence of a
gravitational, vector Aharonov-Bohm effect. A connection is made between the
gravitational, vector Aharonov-Bohm effect and the principle of local gauge
invariance for nonrelativistic quantum matter interacting with weak
gravitational fields. The compensating vector fields that are necessitated by
this local gauge principle are shown to be incorporated by the DeWitt minimal
coupling rule. The nonrelativistic Hamiltonian for weak, time-independent
fields interacting with quantum matter is then extended to time-dependent
fields, and applied to problem of the interaction of radiation with
macroscopically coherent quantum systems, including the problem of
gravitational radiation interacting with superconductors. But first we examine
the interaction of EM radiation with superconductors in a parametric oscillator
consisting of a superconducting wire placed at the center of a high Q
superconducting cavity driven by pump microwaves. We find that the threshold
for parametric oscillation for EM microwave generation is much lower for the
separated configuration than the unseparated one, which then leads to an
observable dynamical Casimir effect. We speculate that a separated parametric
oscillator for generating coherent GR microwaves could also be built.


title:
Mass estimates of rapidly-moving prominence material from high-cadence
  EUV images

abstract:
  We present a new method for determining the column density of erupting
filament material using state-of-the-art multi-wavelength imaging data. Much of
the prior work on filament/prominence structure can be divided between studies
that use a polychromatic approach with targeted campaign observations, and
those that use synoptic observations, frequently in only one or two
wavelengths. The superior time resolution, sensitivity and near-synchronicity
of data from the Solar Dynamics Observatory's Advanced Imaging Assembly allow
us to combine these two techniques using photo-ionisation continuum opacity to
determine the spatial distribution of hydrogen in filament material. We apply
the combined techniques to SDO/AIA observations of a filament which erupted
during the spectacular coronal mass ejection on 2011 June 07. The resulting
'polychromatic opacity imaging' method offers a powerful way to track partially
ionised gas as it erupts through the solar atmosphere on a regular basis,
without the need for co-ordinated observations, thereby readily offering
regular, realistic mass-distribution estimates for models of these erupting
structures.


title: View-based propagation of decomposable constraints

abstract:
  Constraints that may be obtained by composition from simpler constraints are
present, in some way or another, in almost every constraint program. The
decomposition of such constraints is a standard technique for obtaining an
adequate propagation algorithm from a combination of propagators designed for
simpler constraints. The decomposition approach is appealing in several ways.
Firstly because creating a specific propagator for every constraint is clearly
infeasible since the number of constraints is infinite. Secondly, because
designing a propagation algorithm for complex constraints can be very
challenging. Finally, reusing existing propagators allows to reduce the size of
code to be developed and maintained. Traditionally, constraint solvers
automatically decompose constraints into simpler ones using additional
auxiliary variables and propagators, or expect the users to perform such
decomposition themselves, eventually leading to the same propagation model. In
this paper we explore views, an alternative way to create efficient propagators
for such constraints in a modular, simple and correct way, which avoids the
introduction of auxiliary variables and propagators.


title:
A variational approach for calculating Auger electron spectra: going
  beyond the impurity approximation

abstract:
  We propose a novel variational method to calculate the two-hole propagators
relevant for Auger spectroscopy in transition metal oxides. This method can be
thought of as an intermediary step between the full solution (which is
difficult to generalize to systems with partially filled bands) and the
impurity approximation. Like the former, our solution has full translational
invariance, and like the latter, it can be generalized to certain types of
systems with partially filled bands. Here we compare both our variational
approximation and the impurity approximation against the exact solution for a
simple one-dimensional model with filled bands. We show that when the energies
of the eigenstates residing primarily on the transition metal ions do not
overlap with those of the eigenstates residing primarily on Oxygen ions, both
approximations are valid but the variational approach is superior.


title: Loop effects and infrared divergences in slow-roll inflation

abstract:
  Loop corrections to observables in slow-roll inflation are found to diverge
no worse than powers of the log of the scale factor, extending Weinberg's
theorem to quasi-single field inflation models. Demanding perturbation theory
be valid during primordial inflation leads to constraints on the effective
lagrangian. This leads to some interesting constraints and coincidences on the
landscape of inflationary vacua.


title:
Faint Tidal Features in Galaxies within the Canada-France-Hawaii
  Telescope Legacy Survey Wide Fields

abstract:
  We present an analysis of the detectability of faint tidal features in
galaxies from the wide-field component of the Canada-France-Hawaii Telescope
Legacy Survey. Our sample consists of 1781 luminous M_r<-19.3 mag) galaxies in
the magnitude range 15.5<r<17 mag and in the redshift range 0.04<z<0.2.
Although we have classified tidal features according to their morphology (e.g.
streams, shells and tails), we do not attempt to interpret them in terms of
their physical origin (e.g. major versus minor merger debris). Instead, we
provide a catalog that is intended to provide raw material for future
investigations which probe the nature of low surface brightness substructure
around galaxies. We find that around 12% of the galaxies in our sample show
clear tidal features at the highest confidence level. This fraction rises to
about 18% if we include systems with convincing albeit weaker tidal features,
and to 26% if we include systems with more marginal features that may or may
not be tidal in origin. These proportions are a strong function of rest-frame
colour and of stellar mass. Linear features, shells, and fans are much more
likely to occur in massive galaxies with stellar masses >10^10.5 M_sun, and red
galaxies are twice as likely to show tidal features than are blue galaxies.


title:
Reproductive isolation between phylogeographic lineages scales with
  divergence

abstract:
  Phylogeographic studies frequently reveal multiple morphologically-cryptic
lineages within species. What is yet unclear is whether such lineages represent
nascent species or evolutionary ephemera. To address this question, we compare
five contact zones, each of which occurs between eco-morphologically cryptic
lineages of rainforest skinks from the rainforests of the Australian Wet
Tropics. Although the contacts likely formed concurrently in response to
Holocene expansion from glacial refugia, we estimate that the divergence times
(t) of the lineage-pairs range from 3.1 to 11.5 Myr. Multilocus analyses of the
contact zones yielded estimates of reproductive isolation that are tightly
correlated with divergence time and, for longer-diverged lineages (t > 5 Myr),
substantial. These results show that phylogeographic splits of increasing depth
can represent stages along the speciation continuum, even in the absence of
overt change in ecologically relevant morphology.


title:
Frequency dependence of mode coupling gain in Yb doped fiber amplifiers
  due to stimulated thermal Rayleigh scattering

abstract:
  Using a numerical model we study the frequency dependence of mode coupling
gain due to stimulated thermal Rayleigh scattering in step index, Yb doped,
fiber amplifiers. The frequency at the gain peak is shown to vary with core
size, doping size, population saturation, thermal lensing, fiber coiling,
direction of pumping, photodarkening, and pump noise spectra. The predicted
frequencies are compared with measured values whenever possible.


title: Modeled fiber amplifier performance near the mode instability threshold

abstract:
  We numerically model fiber amplifier performance near and slightly above the
mode instability threshold. These results are compared with recently published
experimental work. Using weakly amplitude modulated pump light we obtain
qualitative agreement with the measured instability thresholds, mode switching
ranges, pixel power modulations, and modal amplitude modulations.


title:
On irreducibility of certain Schur polynomials over fields of finite
  characteristic

abstract:
  We present an elementary proof that the Schur polynomial corresponding to an
increasing sequence of exponents (c_0,..., c_{n-1}) with c_0 = 0 is irreducible
over every field of characteristic p whenever the numbers d_i = c_{i+1} - c_i
are all greater than 1, not divisible by p, and satisfy gcd(d_i, d_{i+1}) = 1
for every i.


title: The Density Distribution in Turbulent Bi-stable Flows

abstract:
  We numerically study the volume density probability distribution function
(n-PDF) and the column density probability distribution function (Sigma-PDF)
resulting from thermally bistable turbulent flows. We analyze three-dimensional
hydrodynamic models in periodic boxes of 100pc by side, where turbulence is
driven in the Fourier space at a wavenumber corresponding to 50pc. At low
densities (n <= 0.6cm^-3) the n-PDF, is well described by a lognormal
distribution for average local Mach number ranging from ~0.2 to ~5.5. As a
consequence of the non linear development of thermal instability (TI), the
logarithmic variance of the distribution for the diffuse gas increases with M
faster than in the well known isothermal case. The average local Mach number
for the dense gas (n >= 7.1cm^-3) goes from ~1.1 to ~16.9 and the shape of the
high density zone of the n-PDF changes from a power-law at low Mach numbers to
a lognormal at high M values. In the latter case the width of the distribution
is smaller than in the isothermal case and grows slower with M. At high column
densities the Sigma-PDF is well described by a lognormal for all the Mach
numbers we consider and, due to the presence of TI, the width of the
distribution is systematically larger than in the isothermal case but follows a
qualitatively similar behavior as M increases. Although a relationship between
the width of the distribution and M can be found for each one of the cases
mentioned above, these relations are different form those of the isothermal
case.


title:
Nonequilibrium mode-coupling theory for uniformly sheared underdamped
  systems

abstract:
  Mode-coupling theory for uniformly sheared underdamped systems with an
isothermal condition is presented. As a result of the isothermal condition, it
is shown that the shear stress exhibits significant relaxation at the
alpha-relaxation regime due to the cooling effect which is accompanied by the
growth of the current fluctuation. This indicates that nonequilibrium
underdamped MCT is not equivalent to the corresponding overdamped MCT, even at
long time-scales after the early stage of the beta relaxation. It is verified
that the effect of correlations to the density-current modes is, however,
negligible in sheared thermostated underdamped systems.


title:
Approximate Deconvolution Model in a bounded domain with a vertical
  regularization

abstract:
  We study the global existence issue for a three-dimensional Approximate
Deconvolution Model with a vertical filter. We consider this model in a bounded
cylindrical domain where we construct a unique global weak solution. The proof
is based on a refinement of the energy method given by Berselli in [3].


title:
The 18Ne(a,p)21Na breakout reaction in x-ray bursts: experimental
  determination of spin-parities for alpha resonances in 22Mg via resonant
  elastic scattering of 21Na+p

abstract:
  The $^{18}$Ne($\alpha$,$p$)$^{21}$Na reaction provides a pathway for breakout
from the hot CNO cycles to the $rp$-process in type I x-ray bursts. To better
determine this astrophysical reaction rate, the resonance parameters of the
compound nucleus $^{22}$Mg have been investigated by measuring the resonant
elastic scattering of $^{21}$Na+$p$. An 89 MeV $^{21}$Na radioactive ion beam
was produced at the CNS Radioactive Ion Beam Separator and bombarded an 8.8
mg/cm$^2$ thick polyethylene target. The recoiled protons were measured at
scattering angles of $\theta_{c.m.}$$\approx 175 {^\circ}$ and 152${^\circ}$ by
three $\Delta E$-$E$ silicon telescopes. The excitation function was obtained
with a thick-target method over energies $E_x$($^{22}$Mg)=5.5--9.2 MeV. The
resonance parameters have been determined through an $R$-matrix analysis. For
the first time, the $J^{\pi}$ values for ten states above the alpha threshold
in $^{22}$Mg have been experimentally determined in a single consistent
measurement. We have made three new $J^{\pi}$ assignments and confirmed seven
of the ten tentative assignments in the previous work. The
$^{18}$Ne($\alpha$,$p$)$^{21}$Na reaction rate has been recalculated, and the
astrophysical impact of our new rate has been investigated through one-zone
postprocessing x-ray burst calculations. We find that the
$^{18}$Ne($\alpha$,$p$)$^{21}$Na rate significantly affects the peak nuclear
energy generation rate and the onset temperature of this breakout reaction in
these phenomena.


title: Comparing Gaseous and Stellar Orbits in a Spiral Potential

abstract:
  It is generally assumed that gas in a galactic disk follows closely non
self-intersecting periodic stellar orbits. In order to test this common
assumption, we have performed MHD simulations of a galactic-like disk under the
influence of a spiral galactic potential. We also have calculated the actual
orbit of a gas parcel and compared it to stable periodic stellar orbits in the
same galactic potential and position. We found that the gaseous orbits approach
periodic stellar orbits far from the major orbital resonances only. Gas orbits
initialized at a given galactocentric distance but at different azimuths can be
different, and scattering is conspicuous at certain galactocentric radii. Also,
in contrast to the stellar behaviour, near the 4:1 (or higher order) resonance
the gas follows nearly circular orbits, with much shorter radial excursions
than the stars. Also, since the gas does not settle into a steady state, the
gaseous orbits do not necessarily close on themselves.


title:
On the Method of Interconnection and Damping Assignment Passivity-Based
  Control for the Stabilization of Mechanical Systems

abstract:
  Interconnection and damping assignment passivity-based control (IDA-PBC) is
an excellent method to stabilize mechanical systems in the Hamiltonian
formalism. In this paper, several improvements are made on the IDA-PBC method.
The skew-symmetric interconnection submatrix in the conventional form of
IDA-PBC is shown to have some redundancy for systems with the number of degrees
of freedom greater than two, containing unnecessary components that do not
contribute to the dynamics. To completely remove this redundancy, the use of
quadratic gyroscopic forces is proposed in place of the skew-symmetric
interconnection submatrix. Reduction of the number of matching partial
differential equations in IDA-PBC and simplification of the structure of the
matching partial differential equations are achieved by eliminating the
gyroscopic force from the matching partial differential equations. In addition,
easily verifiable criteria are provided for Lyapunov/exponential
stabilizability by IDA-PBC for all linear controlled Hamiltonian systems with
arbitrary degrees of underactuation and for all nonlinear controlled
Hamiltonian systems with one degree of underactuation. A general design
procedure for IDA-PBC is given and illustrated with examples. The duality of
the new IDA-PBC method to the method of controlled Lagrangians is discussed.
This paper renders the IDA-PBC method as powerful as the controlled Lagrangian
method.


title:
The second order spin-2 system in flat space near space-like and
  null-infinity

abstract:
  In previous work, the numerical solution of the linearized gravitational
field equations near space-like and null-infinity was discussed in the form of
the spin-2 zero-rest-mass equation for the perturbations of the conformal Weyl
curvature. The motivation was to study the behavior of the field and properties
of the numerical evolution of the system near infinity using Friedrich's
conformal representation of space-like infinity as a cylinder. It has been
pointed out by H.O. Kreiss and others that the numerical evolution of a system
using second order wave equations has several advantages compared to a system
of first order equations. Therefore, in the present paper we derive a system of
second order wave equations and prove that the solution spaces of the two
systems are the same if appropriate initial and boundary data are given. We
study the properties of this system of coupled wave equations in the same
geometric setting and discuss the differences between the two approaches.


title: Maximizing Reliability in WDM Networks through Lightpath Routing

abstract:
  We study the reliability maximization problem in WDM networks with random
link failures. Reliability in these networks is defined as the probability that
the logical network is connected, and it is determined by the underlying
lightpath routing, network topologies and the link failure probability. By
introducing the notion of lexicographical ordering for lightpath routings, we
characterize precise optimization criteria for maximum reliability in the low
failure probability regime. Based on the optimization criteria, we develop
lightpath routing algorithms that maximize the reliability, and logical
topology augmentation algorithms for further improving reliability. We also
study the reliability maximization problem in the high failure probability
regime.


title: Measurement of mobility in dual-gated MoS2 transistors

abstract:
  Atomically thin semiconducting MoS2 is of great interest for high-performance
flexible electronic and optoelectronic devices. Initial measurements using
back-gated field-effect transistor (FET) structures on SiO2 yielded mobility of
1-50 cm^2/Vs for few-layer MoS2[1, 2]. Initial measurements using back-gated
field-effect transistor (FET) structures on SiO2 yielded mobility of 1-50
cm^2/Vs for few-layer MoS2[1, 2]. However, greatly increased mobility - as high
as 900 cm^2/Vs - was recently reported for monolayer MoS2 by Radisavljevic, et
al.[Ref. 3; see also Refs. 4-6], and for multilayer MoS2 by others[7, 8], in
devices covered by a high-kappa dielectric layer and a metal top gate. Similar
increases were reported for electrolyte top-gated MoS2[9]. A puzzling common
aspect of these reports is that the double-gated devices consistently show much
higher mobility when measured using the weakly-coupled back gate (typically 300
nm of SiO2) than using the strongly-coupled top gate. While this difference
might be attributed to a different quality of the top and bottom surfaces, the
large discrepancy motivates close examination of the measurement techniques to
rule out spurious effects. Notably, it has been shown that the mobility may be
greatly overestimated in this geometry[10, 11]. There is good evidence that
this is the case here[4-9]; below we discuss Radisavljevic, et al.[4] as an
illustrative example.


title: A geometric protocol for cryptography with cards

abstract:
  In the generalized Russian cards problem, the three players Alice, Bob and
Cath draw a,b and c cards, respectively, from a deck of a+b+c cards. Players
only know their own cards and what the deck of cards is. Alice and Bob are then
required to communicate their hand of cards to each other by way of public
messages. The communication is said to be safe if Cath does not learn the
ownership of any specific card; in this paper we consider a strengthened notion
of safety introduced by Swanson and Stinson which we call k-safety.
  An elegant solution by Atkinson views the cards as points in a finite
projective plane. We propose a general solution in the spirit of Atkinson's,
although based on finite vector spaces rather than projective planes, and call
it the `geometric protocol'. Given arbitrary c,k>0, this protocol gives an
informative and k-safe solution to the generalized Russian cards problem for
infinitely many values of (a,b,c) with b=O(ac). This improves on the collection
of parameters for which solutions are known. In particular, it is the first
solution which guarantees $k$-safety when Cath has more than one card.


title:
First demonstration of a sub-keV electron recoil energy threshold in a
  liquid argon ionization chamber

abstract:
  We describe the first demonstration of a sub-keV electron recoil energy
threshold in a dual-phase liquid argon time projection chamber. This is an
important step in an effort to develop a detector capable of identifying the
ionization signal resulting from nuclear recoils with energies of order a few
keV and below. We obtained this result by observing the peaks in the energy
spectrum at 2.82 keV and 0.27 keV, following the K- and L-shell electron
capture decay of Ar-37, respectively. The Ar-37 source preparation is described
in detail, since it enables calibration that may also prove useful in dark
matter direct detection experiments. An internally placed Fe-55 x-ray source
simultaneously provided another calibration point at 5.9 keV. We discuss the
ionization yield and electron recombination in liquid argon at those three
calibration energies.


title:
A measure of association between vectors based on "similarity
  covariance"

abstract:
  The "maximum similarity correlation" definition introduced in this study is
motivated by the seminal work of Szekely et al on "distance covariance" (Ann.
Statist. 2007, 35: 2769-2794; Ann. Appl. Stat. 2009, 3: 1236-1265). Instead of
using Euclidean distances "d" as in Szekely et al, we use "similarity", which
can be defined as "exp(-d/s)", where the scaling parameter s>0 controls how
rapidly the similarity falls off with distance. Scale parameters are chosen by
maximizing the similarity correlation. The motivation for using "similarity"
originates in spectral clustering theory (see e.g. Ng et al 2001, Advances in
Neural Information Processing Systems 14: 849-856). We show that a particular
form of similarity correlation is asymptotically equivalent to distance
correlation for large values of the scale parameter. Furthermore, we extend
similarity correlation to coherence between complex valued vectors, including
its partitioning into real and imaginary contributions. Several toy examples
are used for comparing distance and similarity correlations. For instance,
points on a noiseless straight line give distance and similarity correlation
values equal to 1; but points on a noiseless circle produces near zero distance
correlation (dCorr=0.02) while the similarity correlation is distinctly non
zero (sCorr=0.36). In distinction to the distance approach, similarity gives
more importance to small distances, which emphasizes the local properties of
functional relations. This paper represents a preliminary empirical study,
showing that the novel similarity association has some distinct practical
advantages over distance based association.For the sake of reproducible
research, the software code implementing all methods here (using lazarus
free-pascal "www.lazarus.freepascal.org"), including all test data, are freely
available at: "sites.google.com/site/pascualmarqui/home/similaritycovariance".


title: On uncertainty and information properties of ranked set samples

abstract:
  Ranked set sampling is a sampling design which has a wide range of
applications in industrial statistics, and environmental and ecological
studies, etc.. It is well known that ranked set samples provide more Fisher
information than simple random samples of the same size about the unknown
parameters of the underlying distribution in parametric inferences. In this
paper, we consider the uncertainty and information content of ranked set
samples in both perfect and imperfect ranking scenarios in terms of Shannon
entropy, R\'enyi and Kullback-Leibler (KL) information measures. It is proved
that under these information measures, ranked set sampling design performs
better than its simple random sampling counterpart of the same size. The
information content is also a monotone function of the set size in ranked set
sampling. Moreover, the effect of ranking error on the information content of
the data is investigated.


title: Latent Relation Representations for Universal Schemas

abstract:
  Traditional relation extraction predicts relations within some fixed and
finite target schema. Machine learning approaches to this task require either
manual annotation or, in the case of distant supervision, existing structured
sources of the same schema. The need for existing datasets can be avoided by
using a universal schema: the union of all involved schemas (surface form
predicates as in OpenIE, and relations in the schemas of pre-existing
databases). This schema has an almost unlimited set of relations (due to
surface forms), and supports integration with existing structured data (through
the relation types of existing databases). To populate a database of such
schema we present a family of matrix factorization models that predict affinity
between database tuples and relations. We show that this achieves substantially
higher accuracy than the traditional classification approach. More importantly,
by operating simultaneously on relations observed in text and in pre-existing
structured DBs such as Freebase, we are able to reason about unstructured and
structured data in mutually-supporting ways. By doing so our approach
outperforms state-of-the-art distant supervision systems.


title: Field-Free Synthetic-Ferromagnet Spin Torque Oscillator

abstract:
  We study the magnetization dynamics of spin valve structures with a free
composite synthetic ferromagnet (SyF) that consists of two ferromagnetic layers
coupled through a normal metal spacer. A ferromagnetically coupled SyF can be
excited into dynamical precessional states by an applied current without
external magnetic fields. We analytically determine the stability of these
states in the space spanned by the current density and SyF interlayer exchange
coupling. Numerical simulations confirm our analytical results.


title: Identifying codes of corona product graphs

abstract:
  For a vertex $x$ of a graph $G$, let $N_G[x]$ be the set of $x$ with all of
its neighbors in $G$. A set $C$ of vertices is an {\em identifying code} of $G$
if the sets $N_G[x]\cap C$ are nonempty and distinct for all vertices $x$. If
$G$ admits an identifying code, we say that $G$ is identifiable and denote by
$\gamma^{ID}(G)$ the minimum cardinality of an identifying code of $G$. In this
paper, we study the identifying code of the corona product $H\odot G$ of graphs
$H$ and $G$. We first give a necessary and sufficient condition for the
identifiable corona product $H\odot G$, and then express $\gamma^{ID}(H\odot
G)$ in terms of $\gamma^{ID}(G)$ and the (total) domination number of $H$.
Finally, we compute $\gamma^{ID}(H\odot G)$ for some special graphs $G$.


title: Information gain in tomography - A quantum signature of chaos

abstract:
  We find quantum signatures of classical chaos in various metrics of
information gain in quantum tomography. We employ a quantum state estimator
based on weak collective measurements of an ensemble of identically prepared
systems. The tomographic measurement record consists of a sequence of
expectation values of a Hermitian operator that evolves under repeated
application of the Floquet map of the quantum kicked top. We find an increase
in information gain and hence higher fidelities in the reconstruction algorithm
when the chaoticity parameter map increases. The results are well predicted by
random matrix theory.


title: Combinatorial Structures on van der Waerden sets

abstract:
  In this paper we provide two results. The first one consists an infinitary
version of the Furstenberg-Weiss Theorem. More precisely we show that every
subset $A$ of a homogeneous tree $T$ such that $\frac{|A\cap
T(n)|}{|T(n)|}\geq\delta$, where T(n) denotes the $n$-th level of $T$, for all
$n$ in a van der Waerden set, for some positive real $\delta$, contains a
strong subtree having a level sets which forms a van der Waerden set.
  The second result is the following. For every sequence $(m_q)_{q}$ of
positive integers and for every real $0<\delta\\leq1$, there exists a sequence
$(n_q)_{q}$ of positive integers such that for every $D\subseteq
\bigcup_k\prod_{q=0}^{k-1}[n_q]$ satisfying $$\frac{\big{|}D\cap
\prod_{q=0}^{k-1} [n_q]\big{|}}{\prod_{q=0}^{k-1}n_q}\geq\delta$$ for every $k$
in a van der Waerden set, there is a sequence $(J_q)_{q}$, where $J_q$ is an
arithmetic progression of length $m_q$ contained in $[n_q]$ for all $q$, such
that $\prod_{q=0}^{k-1}J_q\subseteq D$ for every $k$ in a van der Waerden set.
Moreover, working in an abstract setting, we obtain $J_q$ to be any
configuration of natural numbers that can be found in an arbitrary set of
positive density.


title:
Comparative study of non-invasive force and stress inference methods in
  tissue

abstract:
  In the course of animal development, the shape of tissue emerges in part from
mechanical and biochemical interactions between cells. Measuring stress in
tissue is essential for studying morphogenesis and its physical constraints.
Experimental measurements of stress reported thus far have been invasive,
indirect, or local. One theoretical approach is force inference from cell
shapes and connectivity, which is non-invasive, can provide a space-time map of
stress and relies on prefactors. Here, to validate force- inference methods, we
performed a comparative study of them. Three force-inference methods, which
differ in their approach of treating indefiniteness in an inverse problem
between cell shapes and forces, were tested by using two artificial and two
experimental data sets. Our results using different datasets consistently
indicate that our Bayesian force inference, by which cell-junction tensions and
cell pressures are simultaneously estimated, performs best in terms of accuracy
and robustness. Moreover, by measuring the stress anisotropy and relaxation, we
cross-validated the force inference and the global annular ablation of tissue,
each of which relies on different prefactors. A practical choice of
force-inference methods in distinct systems of interest is discussed.


title: Preventing common hereditary disorders through time-separated twinning

abstract:
  Biomedical advances have led to a relaxation of natural selection in the
human population in developed countries. In the absence of strong purifying
selection, spontaneous and frequently deleterious mutations tend to accumulate
in the human genome and gradually increase the genetic load; that is, the
frequency of potentially lethal genes in the gene pool. Gradual increase in
incidence of many hereditary disorders suggests deleterious impact of the
genetic load on human well being. Many complex diseases such as type 1 and 2
diabetes, autism, bipolar disorder, allergies, Alzheimer disease, and some
cancers show significantly higher concordance in monozygotic (MZ) twins than in
dizygotic twins (DZ) or parent-child pairs, suggesting their etiology is
strongly influenced by genetics. Preventing these diseases based on genetic
data alone is frequently impossible. We hypothesize that the incidence of
complex diseases could be significantly reduced in the future through a
strategy based on time-separated twinning. This strategy involves the
collection and fertilization of human oocytes followed by several rounds of
artificial twinning. If preimplantation genetic screening (PGS) reports no
aneuploidy or known Mendelian disorders, one of the MZ siblings would be
implanted and the remaining embryos cryoconserved. Once the health of the adult
MZ sibling(s) is established, subsequent parenthood with the cryoconserved
twins could substantially lower the incidence of hereditary disorders with
Mendelian or complex etiology. The proposed method of artificial twinning has
the potential to alleviate suffering and reduce the negative social impact
induced by dysgenic effects associated with known and unknown genetic factors.
Time-separated twinning has the capacity to prevent further accumulation of the
genetic load and to provide source of isogenic embryonic stem cells for future
regenerative therapies.


title: Storage codes -- coding rate and repair locality

abstract:
  The {\em repair locality} of a distributed storage code is the maximum number
of nodes that ever needs to be contacted during the repair of a failed node.
Having small repair locality is desirable, since it is proportional to the
number of disk accesses during repair. However, recent publications show that
small repair locality comes with a penalty in terms of code distance or storage
overhead if exact repair is required.
  Here, we first review some of the main results on storage codes under various
repair regimes and discuss the recent work on possible
(information-theoretical) trade-offs between repair locality and other code
parameters like storage overhead and code distance, under the exact repair
regime.
  Then we present some new information theoretical lower bounds on the storage
overhead as a function of the repair locality, valid for all common coding and
repair models. In particular, we show that if each of the $n$ nodes in a
distributed storage system has storage capacity $\ga$ and if, at any time, a
failed node can be {\em functionally} repaired by contacting {\em some} set of
$r$ nodes (which may depend on the actual state of the system) and downloading
an amount $\gb$ of data from each, then in the extreme cases where $\ga=\gb$ or
$\ga = r\gb$, the maximal coding rate is at most $r/(r+1)$ or 1/2, respectively
(that is, the excess storage overhead is at least $1/r$ or 1, respectively).


title:
Numerical Methods for Computing Effective Transport Properties of
  Flashing Brownian Motors

abstract:
  We develop a numerical algorithm for computing the effective drift and
diffusivity of the steady-state behavior of an overdamped particle driven by a
periodic potential whose amplitude is modulated in time by multiplicative noise
and forced by additive Gaussian noise (the mathematical structure of a flashing
Brownian motor). The numerical algorithm is based on a spectral decomposition
of the solution to the Fokker-Planck equation with periodic boundary conditions
and the cell problem which result from homogenization theory. We also show that
the numerical method of Wang, Peskin, Elston (WPE, 2003) for computing said
quantities is equivalent to that resulting from homogenization theory. We show
how to adapt the WPE numerical method to this problem by means of discretizing
the multiplicative noise via a finite-volume method into a discrete-state
Markov jump process which preserves many important properties of the original
continuous-state process, such as its invariant distribution and detailed
balance. Our numerical experiments show the effectiveness of both methods, and
that the spectral method can have some efficiency advantages when treating
multiplicative random noise, particularly with strong volatility.


title: Inferring the Rate-Length Law of Protein Folding

abstract:
  We investigate the rate-length scaling law of protein folding, a key
undetermined scaling law in the analytical theory of protein folding. We
demonstrate that chain length is a dominant factor determining folding times,
and that the unambiguous determination of the way chain length corre- lates
with folding times could provide key mechanistic insight into the folding
process. Four specific proposed laws (power law, exponential, and two stretched
exponentials) are tested against one an- other, and it is found that the power
law best explains the data. At the same time, the fit power law results in
rates that are very fast, nearly unreasonably so in a biological context. We
show that any of the proposed forms are viable, conclude that more data is
necessary to unequivocally infer the rate-length law, and that such data could
be obtained through a small number of protein folding experiments on large
protein domains.


title:
Manipulating Majorana fermions in one-dimensional spin-orbit coupled
  atomic Fermi gases

abstract:
  Majorana fermions are promising candidates for storing and processing
information in topological quantum computation. The ability to control such
individual information carriers in trapped ultracold atomic Fermi gases is a
novel theme in quantum information science. However, fermionic atoms are
neutral and thus are difficult to manipulate. Here, we theoretically
investigate the control of emergent Majorana fermions in one-dimensional
spin-orbit coupled atomic Fermi gases. We discuss (i) how to move Majorana
fermions by increasing or decreasing an effective Zeeman field, which acts like
a solid state control voltage gate; and (ii) how to create a pair of Majorana
fermions by adding a magnetic impurity potential. We discuss the experimental
realization of our control scheme in an ultracold Fermi gas of $^{40}$K atoms.


title: Dynamics of dissipative multiple exciton generation in nanocrystals

abstract:
  The population dynamics of single- and bi-exciton states in semiconductor
nanocrystals is modeled numerically in the presence of Coulomb coupling between
single- and two-exciton states and a dissipation channel in order to study the
transient bi-exciton population that occurs in an optically excited
semiconductor nanocrystal. The results show that the system evolution strongly
changes if the dissipation is included. In a certain range of parameters, the
growth of the exciton number (MEG process) is fast (on picosecond time scale)
and the following decay (Auger process) is much slower (hundreds of
picoseconds). In some cases, the maximum occupation of the bi-exciton state
increases when dissipation is included. The dynamics of an ensemble of
nanocrystals with a certain size dispersion is studied by averaging over the
energy of the bi-exciton state which can be different for each single
nanocrystal. The validity of Markov and secular approximation is also verified.


title: Aspects of ABJ Theory

abstract:
  In this paper we will analyse the deformation of a ABJ theory in harmonic
superspace. So, we will first discuss deformations of the harmonic superspace
by a graviphoton background and then study the ABJ theory in this deformed
harmonic superspace. This deformed ABJ theory will be shown to posses
$\mathcal{N} =6$ supersymmetry. We also discuss the BRST symmetry of this
theory.


title:
Photoluminescence of a microcavity quantum dot system in the quantum
  strong-coupling regime

abstract:
  The Jaynes-Cummings model, describing the interaction between a single
two-level system and a photonic mode, has been used to describe a large variety
of systems, ranging from cavity quantum electrodynamics, trapped ions, to
superconducting qubits coupled to resonators. Recently there has been renewed
interest in studying the quantum strong-coupling (QSC) regime, where states
with photon number greater than one are excited. This regime has been recently
achieved in semiconductor nanostructures, where a quantum dot is trapped in a
planar microcavity. Here we study the quantum strong-coupling regime by
calculating its photoluminescence (PL) properties under a pulsed excitation. We
discuss the changes in the PL as the QSC regime is reached, which transitions
between a peak around the cavity resonance to a doublet. We particularly
examine the variations of the PL in the time domain, under regimes of short and
long pulse times relative to the microcavity decay time.


title: Decohering localized waves

abstract:
  In the absence of confinement localization of waves takes place due to
randomness or nonlinearity and relies on their phase coherence. We
quantitatively probe the sensitivity of localized wave packets to random phase
fluctuations and confirm the necessity of phase coherence for localization.
Decoherence resulting from a dynamical random environment leads to diffusive
spreading and destroys linear and nonlinear localization. We find that maximal
spreading is achieved for optimal phase fluctuation characteristics which is a
consequence of the competition between diffusion due to decoherence and
ballistic transport within the mean free path distance.


title: How To Monitor AGN Intra-Day Variability at 230 GHz

abstract:
  We probe the feasibility of high-frequency radio observations of very rapid
flux variations in compact active galactic nuclei (AGN). Our study assumes
observations at 230 GHz with a small 6-meter class observatory, using the SNU
Radio Astronomical Observatory (SRAO) as example. We find that 33 radio-bright
sources are observable with signal-to-noise ratios larger than ten. We derive
statistical detection limits via exhaustive Monte Carlo simulations assuming
(a) periodic, and (b) episodic flaring flux variations on time-scales as small
as tens of minutes. We conclude that a wide range of flux variations is
observable. This makes high-frequency radio observations - even with small
observatories - a powerful probe of AGN intra-day variability; especially,
those observations complement observations at lower radio frequencies with
larger observatories like the Korean VLBI Network (KVN).


title: Deformations of Fuchsian AdS representations are Quasi-Fuchsian

abstract:
  Let $\Gamma$ be a finitely generated group, and let $\op{Rep}(\Gamma,
\SO(2,n))$ be the moduli space of representations of $\Gamma$ into $\SO(2,n)$
($n \geq 2$). An element $\rho: \Gamma \to \SO(2,n)$ of $\op{Rep}(\Gamma,
\SO(2,n))$ is \textit{quasi-Fuchsian} if it is faithful, discrete, preserves an
acausal subset in the conformal boundary $\Ein_n$ of the anti-de Sitter space;
and if the associated globally hyperbolic anti-de Sitter space is spatially
compact - a particular case is the case of \textit{Fuchsian representations},
i.e. composition of a faithfull, discrete and cocompact representation $\rho_f:
\Gamma \to \SO(1,n)$ and the inclusion $\SO(1,n) \subset \SO(2,n)$. In
\cite{merigot} we proved that quasi-Fuchsian representations are precisely
representations which are Anosov as defined in \cite{labourie}. In the present
paper, we prove that quasi-Fuchsian representations form a connected component
of $\op{Rep}(\Gamma, \SO(2,n))$. This is an almost direct corollary of the
following result: let $\Gamma$ be the fundamental group of a globally
hyperbolic spacetime locally modeled on $\AdS_n$, and let $\rho: \Gamma \to
\SO_0(2,n)$ be the holonomy representation. Then, if $\Gamma$ is Gromov
hyperbolic, the $\rho(\Gamma)$-invariant achronal limit set in $\Ein_n$ is
acausal.


title: Fluctuation corrections on thermodynamic functions: Finite size effect

abstract:
  The explicit thermodynamic functions, in particular, the specific heat of a
spin system interacting with a spin bath which exerts finite dissipation on the
system are determined. We show that the specific heat is a sum of the products
of a thermal equilibration factor that carries the temperature dependence and a
dynamical correction factor, characteristic of the dissipative energy flow
under steady state from the system. The variation of specific heat with
temperature is accompanied by an abrupt transition that depends on these
dynamical factors characteristic of the finite system size.


title: On the heat flux and entropy produced by thermal fluctuations

abstract:
  We report an experimental and theoretical analysis of the energy exchanged
between two conductors kept at different temperature and coupled by the
electric thermal noise. Experimentally we determine, as functions of the
temperature difference, the heat flux, the out-of- equilibrium variance and a
conservation law for the fluctuating entropy, which we justify theoretically.
The system is ruled by the same equations of two Brownian particles kept at
different temperatures and coupled by an elastic force. Our results set strong
constrains on the energy exchanged between coupled nano-systems kept at
different temperature.}


title: Neutrino Mass Matrix Model with a Bilinear Form

abstract:
  A neutrino mass matrix model with a bilinear form $M_\nu = k_\nu (M_D
M_R^{-1} M_D^T)^2$ is proposed within the framework of the so-called yukawaon
model, which has been proposed for the purpose of a unified description of the
lepton mixing matrix $U_{PMNS}$ and the quark mixing matrix $V_{CKM}$. The
model has only two adjustable parameters for the PMNS mixing and neutrino mass
atios. (Other parameters are fixed from the observed quark and charged lepton
mass ratios and the CKM mixing.) The model gives reasonable values $\sin^2
2\theta_{12} \simeq 0.85$ and $\sin^2 2\theta_{23} \sim 1$ and $\sin^2
2\theta_{13} \sim 0.09$ together with $R_\nu \equiv \Delta m^2_{21}/\Delta
m^2_{32} \sim 0.03$. Our prediction of the effective neutrino mass $<m>$ in the
neutrinoless double beta decay takes a sizable value $< m >\simeq 0.0034$ eV.


title:
Creative telescoping for rational functions using the Griffiths-Dwork
  method

abstract:
  Creative telescoping algorithms compute linear differential equations
satisfied by multiple integrals with parameters. We describe a precise and
elementary algorithmic version of the Griffiths-Dwork method for the creative
telescoping of rational functions. This leads to bounds on the order and degree
of the coefficients of the differential equation, and to the first complexity
result which is simply exponential in the number of variables. One of the
important features of the algorithm is that it does not need to compute
certificates. The approach is vindicated by a prototype implementation.


title:
Perturbation analysis for the generalized inverses with prescribed
  idempotents in Banach algebras

abstract:
  In this paper, we first study the perturbations and expressions for the
generalized inverses $a^{(2)}_{p,q}$, $a^{(1, 2)}_{p,q}$, $a^{(2, l)}_{p,q}$
and $a^{(l)}_{p,q}$ with prescribed idempotents $p$ and $q$. Then, we
investigate the general perturbation analysis and error estimate for some of
these generalized inverses when $p,\,q$ and $a$ also have some small
perturbations.


title: A Scalable Hybrid MAC Protocol for Massive M2M Networks

abstract:
  In Machine to Machine (M2M) networks, a robust Medium Access Control (MAC)
protocol is crucial to enable numerous machine-type devices to concurrently
access the channel. Most literatures focus on developing simplex (reservation
or contention based)MAC protocols which cannot provide a scalable solution for
M2M networks with large number of devices. In this paper, a frame-based Hybrid
MAC scheme, which consists of a contention period and a transmission period, is
proposed for M2M networks. In the proposed scheme, the devices firstly contend
the transmission opportunities during the contention period, only the
successful devices will be assigned a time slot for transmission during the
transmission period. To balance the tradeoff between the contention and
transmission period in each frame, an optimization problem is formulated to
maximize the system throughput by finding the optimal contending probability
during contention period and optimal number of devices that can transmit during
transmission period. A practical hybrid MAC protocol is designed to implement
the proposed scheme. The analytical and simulation results demonstrate the
effectiveness of the proposed Hybrid MAC protocol.


title: Extremal Surfaces in Asymptotically AdS Charged Boson Stars Backgrounds

abstract:
  In this paper, inspired by the holographic dual of the entanglement entropy,
we consider the behaviour of extremal, codimension two, spacelike surfaces in
the background of three and four dimensional charged boson stars in
asymptotically anti-de Sitter spacetime. We find conditions for which families
of minimal area surfaces fail to contain the entire bulk spacetime and
construct a phase diagram showcasing the transition between regimes. In
addition, we use the relation between the star's mass and the central density
of the scalar field to argue for a possible instability of such hollow
solutions. Finally, we discuss the consequences of our findings for the study
of holographic duals of reduced density matrices.


title: Identification of three-qubit entanglement

abstract:
  We present a way of identifying all kinds of entanglement for three-qubit
pure states in terms of the expectation values of Pauli operators. The
necessary and sufficient conditions to classify the fully separable,
biseparable, and genuine entangled states are explicitly given. The approach
can be generalized to multipartite high-dimensional cases. For three-qubit
mixed states, we propose two kinds of inequalities in terms of the expectation
values of complementary observables. One inequality has advantages in
entanglement detection of the quantum state with positive partial
transpositions, and the other is able to detect genuine entanglement. The
results give an effective method for experimental entanglement identification.


title: QCD with Two Light Dynamical Chirally Improved Quarks: Baryons

abstract:
  We present a study of baryon ground states and low lying excitations of
non-strange and strange baryons. The results are based on seven gauge field
ensembles with two dynamical light Chirally Improved (CI) quarks corresponding
to pion masses between 255 and 596 MeV and a strange valence quark with mass
fixed by the Omega baryon. The lattice spacing varies between 0.1324 and 0.1398
fm. Given in lattice units, the bulk of our results are for size 16^3\times 32,
for two ensembles with light pion masses (255 and 330 MeV) we also use
24^3\times 48 lattices and perform an infinite volume extrapolation. We derive
energy levels for the spin 1/2 and 3/2 channels for both parities. In general,
our results in the infinite volume limit compare well with experiment. We
analyze the flavor symmetry content by identifying the singlet/octet/decuplet
contributions of the resulting eigenstates. The ground states compositions
agree with quark model expectations. In some cases the excited states, however,
disagree and we discuss possible reasons.


title: Enhancing efficacy in laser projection by four wavelength combination

abstract:
  In this letter we present a novel study about the combination of four laser
wavelengths in order to maximize both color gamut and efficacy to produce the
color white. Firstly, an analytic method to calculate efficacy as function of
both four laser wavelegths and four laser powers is derived. Secondly we
provide a new way to present the results by providing the diagram efficacy vs
color gamut area that summarizes the performance of any wavelength combination
for projection purposes. The results indicate that the maximal efficacy for the
D65 white is only achievable by using a suitable combination of both laser
power ratios and wavelengths.


title:
Cross Validation and Maximum Likelihood estimations of hyper-parameters
  of Gaussian processes with model misspecification

abstract:
  The Maximum Likelihood (ML) and Cross Validation (CV) methods for estimating
covariance hyper-parameters are compared, in the context of Kriging with a
misspecified covariance structure. A two-step approach is used. First, the case
of the estimation of a single variance hyper-parameter is addressed, for which
the fixed correlation function is misspecified. A predictive variance based
quality criterion is introduced and a closed-form expression of this criterion
is derived. It is shown that when the correlation function is misspecified, the
CV does better compared to ML, while ML is optimal when the model is
well-specified. In the second step, the results of the first step are extended
to the case when the hyper-parameters of the correlation function are also
estimated from data.


title:
Asymptotic analysis of the role of spatial sampling for covariance
  parameter estimation of Gaussian processes

abstract:
  Covariance parameter estimation of Gaussian processes is analyzed in an
asymptotic framework. The spatial sampling is a randomly perturbed regular grid
and its deviation from the perfect regular grid is controlled by a single
scalar regularity parameter. Consistency and asymptotic normality are proved
for the Maximum Likelihood and Cross Validation estimators of the covariance
parameters. The asymptotic covariance matrices of the covariance parameter
estimators are deterministic functions of the regularity parameter. By means of
an exhaustive study of the asymptotic covariance matrices, it is shown that the
estimation is improved when the regular grid is strongly perturbed. Hence, an
asymptotic confirmation is given to the commonly admitted fact that using
groups of observation points with small spacing is beneficial to covariance
function estimation. Finally, the prediction error, using a consistent
estimator of the covariance parameters, is analyzed in details.


title:
Can quantum gravity be exposed in the laboratory?: A tabletop experiment
  to reveal the quantum foam

abstract:
  I propose an experiment that may be performed, with present low temperature
and cryogenic technology, to reveal Wheeler's quantum foam. It involves
coupling an optical photon's momentum to the center of mass motion of a
macroscopic transparent block with parameters such that the latter is displaced
in space by approximately a Planck length. I argue that such displacement is
sensitive to quantum foam and will react back on the photon's probability of
transiting the block. This might allow determination of the precise scale at
which quantum fluctuations of space-time become large, and so differentiate
between the brane-world and the traditional scenarios of spacetime.


title:
Bending elasticity of macromolecules: analytic predictions from the
  wormlike chain model

abstract:
  We present a study of the bend angle distribution of semiflexible polymers of
short and intermediate lengths within the wormlike chain model. This enables us
to calculate the elastic response of a stiff molecule to a bending moment. Our
results go beyond the Hookean regime and explore the nonlinear elastic
behaviour of a single molecule. We present analytical formulae for the bend
angle distribution and for the moment-angle relation. Our analytical study is
compared against numerical Monte Carlo simulations. The functional forms
derived here can be applied to fluorescence microscopic studies on actin and
DNA. Our results are relevant to recent studies in "kinks" and cyclization in
short and intermediate length DNA strands.


title: Size scaling of static friction

abstract:
  Sliding friction across a thin soft lubricant film typically occurs by
stick-slip, the lubricant fully solidifying at stick, yielding and flowing at
slip. The static friction force per unit area preceding slip is known from
molecular dynamics (MD) simulations to decrease with increasing contact area.
That makes the large-size fate of stick-slip unclear and unknown; its possible
vanishing is important as it would herald smooth sliding with a dramatic drop
of kinetic friction at large size. Here we formulate a scaling law of the
static friction force, which for a soft lubricant is predicted to decrease as
f_m + \Delta f /A^gamma for increasing contact area A, with gamma>0. Our main
finding is that the value of f_m, controlling the survival of stick-slip at
large size, can be evaluated by simulations of comparably small size. MD
simulations of soft lubricant sliding are presented, which verify this theory.


title:
Long-range Coulomb interactions in surface systems: a first principles
  description within self-consistently combined GW and dynamical mean field
  theory

abstract:
  Systems of adatoms on semiconductor surfaces display competing ground states
and exotic spectral properties typical of two-dimensional correlated electron
materials which are dominated by a complex interplay of spin and charge degrees
of freedom. We report a fully ab initio derivation of low energy Hamiltonians
for the adatom systems Si(111):X, with X=Sn, Si, C, Pb, that we solve within
self-consistent combined GW and dynamical mean field theory ("GW+DMFT").
Calculated photoemission spectra are in agreement with available experimental
data. We rationalize experimentally observed tendencies from Mott physics
towards charge-ordering along the series as resulting from substantial
long-range interactions.


title: Dynamical analysis of the cosmology of mass-varying massive gravity

abstract:
  We study cosmological evolutions of the generalized model of nonlinear
massive gravity in which the graviton mass is given by a rolling scalar field
and is varying along time. By performing dynamical analysis, we derive the
critical points of this system and study their stabilities. These critical
points can be classified into two categories depending on whether they are
identical with the traditional ones obtained in General Relativity. We discuss
the cosmological implication of relevant critical points.


title:
Cosmological equivalence between the Finsler-Randers space-time and the
  DGP gravity model

abstract:
  We perform a detailed comparison between the Finsler-Randers cosmological
model and the Dvali, Gabadadze and Porrati braneworld model. If we assume that
the spatial curvature is strictly equal to zero then we prove the following
interesting proposition: {\it despite the fact that the current cosmological
models have a completely different geometrical origin they share exactly the
same Hubble expansion}. This implies that the Finsler-Randers model is
cosmologically equivalent with that of the DGP model as far as the cosmic
expansion is concerned. At the perturbative level we find that the
Finsler-Randers growth index of matter perturbations is $\gamma_{FR} \simeq
9/14$ which is somewhat lower than that of DGP gravity ($\gamma_{DGP} \simeq
11/16$) implying that the growth factor of the Finsler-Randers model is
slightly different ($\sim 0.1-2%$) from the one provided by the DGP gravity
model.


title: What is a quantum-mechanical 'weak value' the value of?

abstract:
  A so called 'weak value' of an observable in quantum mechanics (QM) may be
obtained in a weak measurement + post-selection procedure on the QM system
under study. Applied to number operators, it has been invoked in revisiting
some QM paradoxes (e.g., the so called Three Box paradox and Hardy s paradox).
This requires the weak value to be interpreted as a bona fide property of the
system considered, a par with entities like operator mean values and
eigenvalues. I question such an interpretation; it has no support in the basic
axioms of quantum mechanics and it leads to unreasonable results in concrete
situations.


title: Ultraviolet properties of Galactic globular clusters with GALEX

abstract:
  We present ultraviolet (UV) integrated colors of 44 Galactic globular
clusters (GGCs) observed with the Galaxy Evolution Explorer (GALEX) in both FUV
and NUV bands. We find for the first time that GCs associated with the
Sagittarius dwarf galaxy have (FUV-V) colors systematically redder than GGCs
with the same metallicity. M31 GCs show almost the same UV colors as GGCs,
while M87 are systematically bluer. We speculate about the presence of an
interesting trend, suggesting that the UV color of GCs may be correlated with
the mass of the host galaxy, in the sense that more massive galaxies possess
bluer clusters.


title: Volume Free Electron Laser - Self-Phase-Locking System

abstract:
  It is shown that that the Volume free electron laser is a self-phase-locking
system. Equations are derived that describe both the phase-locking process and
the dependence of generation on the times of bunches' entering into the VFEL
resonator in the superradiation regime and for long pulses. The derived
equations are applicable to the description of the stated processes in gratings
formed by relativistic BWOs.


title: Structures and waves in a nonlinear heat-conducting medium

abstract:
  The paper is an overview of the main contributions of a Bulgarian team of
researchers to the problem of finding the possible structures and waves in the
open nonlinear heat conducting medium, described by a reaction-diffusion
equation. Being posed and actively worked out by the Russian school of A. A.
Samarskii and S.P. Kurdyumov since the seventies of the last century, this
problem still contains open and challenging questions.