title: The Gauss-Bonnet Formula for Harmonic Surfaces

abstract:
  We consider harmonic immersions in $\R^{\N}$ of compact Riemann surfaces with
finitely many punctures where the harmonic coordinate functions are given as
real parts of meromorphic functions. We prove that such surfaces have finite
total Gauss curvature. The contribution of each end is a multiple of $2\pi$,
determined by the maximal pole order of the meromorphic functions. This
generalizes the well known Gackstatter-Jorge-Meeks formula for minimal
surfaces. The situation is complicated as the ends are generally not
conformally equivalent to punctured disks, nor does the surface have limit
tangent planes.


title: Spacecraft charging: incoming and outgoing electrons

abstract:
  This paper presents an overview of the roles played by incoming and outgoing
electrons in spacecraft surface and stresses the importance of surface
conditions for spacecraft charging. The balance between the incoming electron
current from the ambient plasma and the outgoing currents of secondary
electrons, backscattered electrons, and photoelectrons from the surfaces
determines the surface potential. Since surface conditions significantly affect
the outgoing currents, the critical temperature and the surface potential are
also significantly affected. As a corollary, high level differential charging
of adjacent surfaces with very different surface conditions is a space hazard.


title:
Carboplatin binding to a model protein in non-NaCl conditions to
  eliminate partial conversion to cisplatin, and the use of different criteria
  to choose the resolution limit

abstract:
  Hen egg white lysozyme (HEWL) co-crystallisation conditions of carboplatin
without sodium chloride (NaCl) have been utilised to eliminate partial
conversion of carboplatin to cisplatin observed previously. Tetragonal HEWL
crystals were successfully obtained in 65% MPD with 0.1M citric acid buffer at
pH 4.0 including DMSO. The X-ray diffraction data resolution to be used for the
model refinement was reviewed using several topical criteria together. The
CC1/2 criterion implemented in XDS led to data being significant to 2.0{\AA},
compared to the data only being able to be processed to 3.0{\AA} using the
Bruker software package (SAINT). Then using paired protein model refinements
and DPI values based on the FreeR value, the resolution limit was fine tuned to
be 2.3{\AA}. Interestingly this was compared with results from the EVAL
software package which gave a resolution limit of 2.2{\AA} solely using
<I/sigI> crossing 2, but 2.8{\AA} based on the Rmerge values (60%). The
structural results showed that carboplatin bound to only the N{\delta} binding
site of His-15 one week after crystal growth, whereas five weeks after crystal
growth, two molecules of carboplatin are bound to the His-15 residue. In
summary several new results have emerged: - firstly non-NaCl conditions showed
a carboplatin molecule bound to His-15 of HEWL; secondly binding of one
molecule of carboplatin was seen after one week of crystal growth and two
molecules were bound after five weeks of crystal growth; and thirdly the use of
several criteria to determine the diffraction resolution limit led to the
successful use of data to higher resolution.


title: DNA origami and the complexity of Eulerian circuits with turning costs

abstract:
  Building a structure using self-assembly of DNA molecules by origami folding
requires finding a route for the scaffolding strand through the desired
structure. When the target structure is a 1-complex (or the geometric
realization of a graph), an optimal route corresponds to an Eulerian circuit
through the graph with minimum turning cost. By showing that it leads to a
solution to the 3-SAT problem, we prove that the general problem of finding an
optimal route for a scaffolding strand for such structures is NP-hard. We then
show that the problem may readily be transformed into a Traveling Salesman
Problem (TSP), so that machinery that has been developed for the TSP may be
applied to find optimal routes for the scaffolding strand in a DNA origami
self-assembly process. We give results for a few special cases, showing for
example that the problem remains intractable for graphs with maximum degree 8,
but is polynomial time for 4-regular plane graphs if the circuit is restricted
to following faces. We conclude with some implications of these results for
related problems, such as biomolecular computing and mill routing problems.


title: Electron cloud effects: codes and simulations at KEK

abstract:
  Electron cloud effects had been studied at KEK-Photon Factory since 1995. e-p
instability had been studied in proton rings since 1965 in BINP, ISR and PSR.
Study of electron cloud effects with the present style, which was based on
numerical simulations, started at 1995 in positron storage rings. The
instability observed in KEKPF gave a strong impact to B factories, KEKB and
PEPII, which were final stage of their design in those days. History of cure
for electron cloud instability overlapped the progress of luminosity
performance in KEKB. The studies on electron cloud codes and simulations in KEK
are presented.


title:
On the Bakry-\'Emery condition, the gradient estimates and the
  Local-to-Global property of RCD*(K,N) metric measure spaces

abstract:
  We prove higher summability and regularity of \Gamma(f) for functions f in
spaces satisfying the Bakry-\'Emery condition BE(K,\infty). As a byproduct, we
obtain various equivalent weak formulations of BE(K,N) and we prove the
Local-to-Global property of the RCD*(K,N) condition in locally compact metric
measure spaces (X,d,m), without assuming a priori the non-branching condition
on the metric space.


title:
Generalizing the self-healing diffusion Monte Carlo approach to finite
  temperature: a path for the optimization of low-energy many-body bases

abstract:
  A statistical method is derived for the calculation of thermodynamic
properties of many-body systems at low temperatures. This method is based on
the self-healing diffusion Monte Carlo method for complex functions [F. A.
Reboredo J. Chem. Phys. 136, 204101 (2012)] and some ideas of the correlation
function Monte Carlo approach [D. M. Ceperley and B. Bernu, J. Chem. Phys. 89,
6316 (1988)]. In order to allow the evolution in imaginary time to describe the
density matrix, we remove the fixed-node restriction using complex
antisymmetric guiding wave functions. In the process we obtain a parallel
algorithm that optimizes a small subspace of the many-body Hilbert space to
have maximum overlap with the subspace spanned by the lowest-energy eigenstates
of a many-body Hamiltonian. We show in a model system that the partition
function is progressively maximized within this subspace. We show that the
subspace spanned by the small basis systematically converges towards the
subspace spanned by the lowest energy eigenstates. Possible applications of
this method to calculate the thermodynamic properties of many-body systems near
the ground state are discussed. The resulting basis can be also used to
accelerate the calculation of the ground or excited states with Quantum Monte
Carlo.


title: On a fractional Nirenberg problem, part II: existence of solutions

abstract:
  This paper is a continuation of our earlier work "[T. Jin, Y.Y. Li and J.
Xiong, On a fractional Nirenberg problem, part I: blow up analysis and
compactness of solutions, to appear in J. Eur. Math. Soc.]", where compactness
results were given on a fractional Nirenberg problem. We prove two existence
results stated there. We also obtain a fractional Aubin inequality.


title: Volatility occupation times

abstract:
  We propose nonparametric estimators of the occupation measure and the
occupation density of the diffusion coefficient (stochastic volatility) of a
discretely observed It\^{o} semimartingale on a fixed interval when the mesh of
the observation grid shrinks to zero asymptotically. In a first step we
estimate the volatility locally over blocks of shrinking length, and then in a
second step we use these estimates to construct a sample analogue of the
volatility occupation time and a kernel-based estimator of its density. We
prove the consistency of our estimators and further derive bounds for their
rates of convergence. We use these results to estimate nonparametrically the
quantiles associated with the volatility occupation measure.


title: Electron cloud observations at the ISIS Proton Synchrotron

abstract:
  The build up of electron clouds inside a particle accelerator vacuum chamber
can produce strong transverse and longitudinal beam instabilities which in turn
can lead to high levels of beam loss often requiring the accelerator to be run
below its design specification. To study the behaviour of electron clouds at
the ISIS Proton Synchrotron, a Micro-Channel Plate (MCP) based electron cloud
detector has been developed. The detector is based on the Retarding Field
Analyser (RFA) design and consists of a retarding grid, which allows energy
analysis of the electron signal, and a MCP assembly placed in front of the
collector plate. The MCP assembly provides a current gain over the range 300 to
25K, thereby increasing the signal to noise ratio and dynamic range of the
measurements. This paper presents the first electron cloud observations at the
ISIS Proton Synchrotron. These results are compared against signals from a beam
position monitor and a fast beam loss monitor installed at the same location.


title:
Strong excitation of emitters in an impedance matched cavity: the area
  theorem, \pi-pulse and self-induced transparency

abstract:
  I theoretically study the behavior of strong pulses exciting emitters inside
a cavity. The ensemble is supposed to be inhomogeneously broadened and the
cavity matched finding application in quantum storage of optical or RF photons.
My analysis is based on energy and pulse area conservation rules predicting
important distortions for specific areas. It is well supported by numerical
simulations. I propose a qualitative interpretation in terms of slow-light. The
analogy with the free space situation is remarkable.


title:
Hermite functions with discontinuous coefficients for the solution of
  fractal diffusion retrospective problems

abstract:
  In this article we study the retrospective inverse problem. The retrospective
inverse problem consists of in the reconstruction of a priori unknown initial
condition of the dynamic system from its known final condition. Existence and
uniqueness of the solution is proved.


title: Bipartite-Finsler spaces and the bumblebee model

abstract:
  We present a proposal to include Lorentz-violating effects in gravitational
field by means of the Finsler geometry. In the Finsler set up, the length of an
event depends both on the point and the direction in the space-time. We briefly
review the bumblebee model, where the Lorentz violation is induced by a
spontaneous symmetry breaking due to the bumblebee vector field.The main
geometrical concepts of the Finsler geometry are outlined. Using a Finslerian
Einstein-Hilbert action we derive the bumblebee action from the bipartite
Finsler function with a correction to the gravitational constant.


title:
The Angular Broadening of the Galactic Center Pulsar SGR J1745-29: A New
  Constraint on the Scattering Medium

abstract:
  The pulsed radio emission from the Galactic Center (GC) magnetar SGR J1745-29
probes the turbulent, magnetized plasma of the GC hyperstrong scattering screen
through both angular and temporal broadening. We present the first measurements
of the angular size of SGR J1745-29, obtained with the Very Long Baseline Array
and the phased Very Large Array at 8.7 and 15.4 GHz. The source sizes are
consistent with the scatter--broadened size of Sagittarius A* at each
frequency, demonstrating that SGR J1745-29 is also located behind the same
hyperstrong scattering medium. Combining the angular broadening with temporal
scattering obtained from pulsar observations provides a complete picture of the
scattering properties. If the scattering occurs in a thin screen, then it must
be at a distance \Delta >~ 5 kpc. A best-fit solution for the distance of a
thin screen is \Delta=5.9 +/-0.3 kpc, consistent with being located in the
Scutum spiral arm. This is a substantial revision of the previously held model
in which the scattering screen is located very close to the GC. As also
discussed in Spitler et al., these results suggest that GC searches can detect
millisecond pulsars gravitationally bound to Sgr A* with observations at >~ 10
GHz and ordinary pulsars at even lower frequencies.


title:
Pulse Broadening Measurements from the Galactic Center Pulsar
  J1745--2900

abstract:
  We present temporal scattering measurements of single pulses and average
profiles of PSR J1745--2900, a magnetar recently discovered only 3 arcsec away
from Sagittarius A* (Sgr A*), from 1.2 - 18.95 GHz using the Effelsberg 100-m
Radio Telescope, the Nan\c{c}ay Decimetric Radio Telescope, and the Jodrell
Bank Lovell Telescope. Single pulse analysis shows that the integrated pulse
profile above 2 GHz is dominated by pulse jitter, while below 2 GHz the pulse
profile shape is dominated by scattering. The high dispersion measure and
rotation measure of the magnetar suggest that it is close to Sgr A* (within
~0.1 pc). This is the first object in the GC with both pulse broadening and
angular broadening measurements. We measure a pulse broadening spectral index
of alpha = -3.8 +/- 0.2 and a pulse broadening time scale at 1 GHz of tau_GHz =
1.3 +/- 0.2 s, which is several orders of magnitude lower than the scattering
predicted by the NE2001 model (Cordes and Lazio 2002). If this scattering
timescale is representative of the GC as a whole, then previous surveys should
have detected many pulsars. The lack of detections implies either our
understanding of scattering in the GC is incomplete or there are fewer pulsars
in the GC than previously predicted. Given that magnetars are a rare class of
radio pulsar, we believe that there are many canonical and millisecond pulsars
in the GC, and not surprisingly, scattering regions in the GC have complex
spatial structures.


title:
Quasi-elastic scattering in the 20Ne + 90,92Zr reactions: role of
  non-collective excitations

abstract:
  Conventional coupled-channels analyses, that take account of only the
collective excitations of the colliding nuclei, have failed to reproduce the
different behavior of the experimental quasi-elastic barrier distributions for
the $^{20}$Ne + $^{90,92}$Zr systems. To clarify the origins of this
difference, we investigate the effect of non-collective excitations of the Zr
isotopes. Describing these excitations in a random-matrix model, we explicitly
take them into account in our coupled-channels calculations. The non-collective
excitations are capable of reproducing the observed smearing of the peak
structure in the barrier distribution for $^{20}$Ne + $^{92}$Zr, while not
significantly altering the structure observed in the $^{20}$Ne + $^{90}$Zr
system. The difference is essentially related to the closed neutron shell in
$^{90}$Zr.


title: The Sub-bandgap Photoconductivity in InGaAs:ErAs Nanocomposites

abstract:
  The photoconductions of ultrafast InGaAs:ErAs nanocomposites at low
temperatures were investigated. The parabolic Tauc edge as well as the
exponential Urbach tail are identified in the absorption spectrum. The Tauc
edge supports that the density of states at the bottom of conduction band is
proportional to the square root of energy. The Urbach edge is attributed to
interband transition caused by smooth microscopic internal fields. The square
root of mean-squared internal fields, whose distribution is Gaussian, is found
in the order of $10^{5}$V/cm, agreeing very well with the theoretical
predictions by Esser (B. ~ Esser, Phys. stat. sol. (b), vol. 51, 735 (1972)).


title: Tunable non-equilibrium dynamics: field quenches in spin ice

abstract:
  We present non-equilibrium physics in spin ice as a novel setting which
combines kinematic constraints, emergent topological defects, and magnetic long
range Coulomb interactions. In spin ice, magnetic frustration leads to highly
degenerate yet locally constrained ground states. Together, they form a highly
unusual magnetic state -- a "Coulomb phase" -- whose excitations are pointlike
defects -- magnetic monopoles -- in the absence of which effectively no
dynamics is possible. Hence, when they are sparse at low temperature, dynamics
becomes very sluggish. When quenching the system from a monopole-rich to a
monopole-poor state, a wealth of dynamical phenomena occur the exposition of
which is the subject of this article. Most notably, we find reaction diffusion
behaviour, slow dynamics due to kinematic constraints, as well as a regime
corresponding to the deposition of interacting dimers on a honeycomb lattice.
We also identify new potential avenues for detecting the magnetic monopoles in
a regime of slow-moving monopoles. The interest in this model system is further
enhanced by its large degree of tunability, and the ease of probing it in
experiment: with varying magnetic fields at different temperatures, geometric
properties -- including even the effective dimensionality of the system -- can
be varied. By monitoring magnetisation, spin correlations or zero-field Nuclear
Magnetic Resonance, the dynamical properties of the system can be extracted in
considerable detail. This establishes spin ice as a laboratory of choice for
the study of tunable, slow dynamics.


title: Pion Nucleon Scattering: Some Results from Lattice QCD

abstract:
  Including the meson-baryon (5 quark) intermediate states in a lattice
simulation is challenging. However, it is important in order to obtain the
correct energy eigenstates and to relate them to scattering phase shifts.
Recent results for the negative parity nucleon channel and the problem of
baryonic resonances in lattice calculations are discussed.


title: Reminiscences of Wit Busza and 41 Years of p+A Physics

abstract:
  One of the more memorable (and easiest) proposal to deal with when I served
on Bob Wilson's Program Advisory Committee at NAL (Now Fermilab) from 1972-75
was Proposal-178, "A study of the average multiplicity and multiplicity
distributions in hadron-nucleus collisions at high energies", with only 4
authors, Wit Busza, Jerry Friedman, Henry Kendall and Larry Rosenson, as
presented at the PAC meeting by Wit. What I remember was that he discussed only
ONE 5 inch photomultiplier with a Cherenkov radiator in the beam to make this
measurement of production of charged particles with angles up to 30 degrees in
various nuclei, 40 hours requested. This turned out to be a "seminal"
experiment leading to the Wounded Nucleon and other participant models.
Subsequent p(d)+A experiments from the AGS to RHIC, as well as alpha-alpha
measurements at the CERN-ISR, will be discussed together with the various
`participants' that they revealed.


title:
Circumbinary Planet Formation in the Kepler-16 System. II. A Toy Model
  for In-situ Planet Formation within a Debris Belt

abstract:
  Recent simulations have shown that the formation of planets in circumbinary
configurations (such as those recently discovered by Kepler) is dramatically
hindered at the planetesimal accretion stage. The combined action of the binary
and the protoplanetary disk acts to raise impact velocities between km-sized
planetesimals beyond their destruction threshold, halting planet formation
within at least 10 AU from the binary. It has been proposed that a primordial
population of "large" planetesimals (100 km or more in size), as produced by
turbulent concentration mechanisms, would be able to bypass this bottleneck;
however, it is not clear whether these processes are viable in the highly
perturbed circumbinary environments. We perform two-dimensional hydrodynamical
and N-body simulations to show that km-sized planetesimals and collisional
debris can drift and be trapped in a belt close to the central binary. Within
this belt, planetesimals could initially grow by accreting debris, ultimately
becoming "indestructible" seeds that can accrete other planetesimals in-situ
despite the large impact speeds. We find that large, indestructible
planetesimals can be formed close to the central binary within $10^5$ years,
therefore showing that even a primordial population of "small" planetesimals
can feasibly form a planet.


title: Quantum Hall fluids in the presence of topological defects

abstract:
  We review our recent results on the physics of quantum Hall fluids at Jain
and non conventional fillings within a general field theoretic framework. We
focus on a peculiar conformal field theory (CFT), the one obtained by means of
the m-reduction technique, and stress its power in describing strongly
correlated low dimensional condensed matter systems in the presence of
localized impurities or topological defects. By exploiting the notion of Morita
equivalence for field theories on noncommutative two-tori and choosing rational
values of the noncommutativity parameter, we find a general one-to-one
correspondence between the m-reduced conformal field theory describing the
quantum Hall fluid and an Abelian noncommutative field theory. As an example of
application of the formalism, we study a quantum Hall bilayer at
nonconventional fillings in the presence of a localized topological defect and
briefly recall its boundary state structure corresponding to two different
boundary conditions, the periodic as well as the twisted boundary conditions
respectively, which give rise to different topological sectors on a torus. Then
we introduce generalized magnetic translation operators as tensor products,
which act on the quantum Hall fluid and defect space respectively, and compute
their action on the boundary partition functions: in this way their role as
boundary condition changing operators is fully evidenced. From such results we
infer the general structure of generalized magnetic translations in our model
and clarify the deep relation between noncommutativity and non-Abelian
statistics of quasi-hole excitations, which is crucial for physical
implementations of topological quantum computing.


title: Color entanglement for azimuthal asymmetries in the Drell-Yan process

abstract:
  In the resummation of collinear gluons emitted together with active partons
from the hadrons in the Drell-Yan process (DY) effects of color entanglement
become important when the transverse directions are taken into account. It is
then no longer possible to write the cross section as the convolution of two
soft correlators and a hard part. We show that the color entanglement
introduces additional color factors that must be taken into account in the
extraction of transverse momentum dependent parton distribution functions (TMD
PDFs) from azimuthal asymmetries. Examples where such effects matter are the
extraction of the double Sivers and double Boer-Mulders asymmetries.
Furthermore, we will argue why this color entanglement is a basic ingredient
already in the tree-level description of azimuthal asymmetries.


title:
On the response of an antenna to polarized electromagnetic plane waves
  using a tensorial and spinorial approach

abstract:
  Geometric Polarimetry has recently been introduced as a new analytical
framework to express fundamental relationships in polarimetry, characterizing
these in geometric terms which guarantees their invariance with respect to
spatial reference frame and choice of basis. It was shown via a rigorous
derivation from Maxwell's equations that there is a formal argument for
representing elementary coherent states algebraically as spinors, and
geometrically as generators of the Poincare' sphere. While it was only
considered the characterization of field states, there is in remote sensing
contexts a corresponding need also to characterize the polarization states of
antennas. This needs to be completely generic and not dependent on the detailed
structure of the antenna. This paper presents a derivation based on
Schelkunov's reaction theorem which fulfils these requirements. The statement
of the theorem is translated from its usual form to a tensor representation,
and this is finally reduced to obtain the new spinor representation of the
antenna in terms of its polarization spinor and its phase flag.


title: Steady self-diffusion in classical gases

abstract:
  A steady self-diffusion process in a gas of hard spheres at equilibrium is
analyzed. The system exhibits a constant gradient of labeled particles. Neither
the concentration of these particles nor its gradient are assumed to be small.
It is shown that the Boltzmann-Enskog kinetic equation has an exact solution
describing the state. The hydrodynamic transport equation for the density of
labeled particles is derived, with an explicit expression for the involved
self-diffusion transport coefficient. Also an approximated expression for the
one-particle distribution function is obtained. The system does not exhibit any
kind of rheological effects. The theoretical predictions are compared with
numerical simulations using the direct simulation Monte Carlo method and a
quite good agreement is found.


title: Quantitative Grothendieck Property

abstract:
  A Banach space $X$ is Grothendieck if the weak and the weak$^*$ convergence
of sequences in the dual space $X^*$ coincide. The space $\ell^\infty$ is a
classical example of a Grothendieck space due to Grothendieck. We introduce a
quantitative version of the Grothendieck property, we prove a quantitative
version of the above-mentioned Grothendieck's result and we construct a
Grothendieck space which is not quantitatively Grothendieck. We also establish
the quantitative Grothendieck property of $L^\infty(\mu)$ for a $\sigma$-finite
measure $\mu$.


title:
ADM-like Hamiltonian formulation of gravity in the teleparallel
  geometry: derivation of constraint algebra

abstract:
  We derive a new constraint algebra for a Hamiltonian formulation of the
Teleparallel Equivalent of General Relativity treated as a theory of cotetrad
fields on a spacetime. The algebra turns out to be closed.


title:
Robust Inference on Average Treatment Effects with Possibly More
  Covariates than Observations

abstract:
  This paper concerns robust inference on average treatment effects following
model selection. In the selection on observables framework, we show how to
construct confidence intervals based on a doubly-robust estimator that are
robust to model selection errors and prove that they are valid uniformly over a
large class of treatment effect models. The class allows for multivalued
treatments with heterogeneous effects (in observables), general
heteroskedasticity, and selection amongst (possibly) more covariates than
observations. Our estimator attains the semiparametric efficiency bound under
appropriate conditions. Precise conditions are given for any model selector to
yield these results, and we show how to combine data-driven selection with
economic theory. For implementation, we give a specific proposal for selection
based on the group lasso, which is particularly well-suited to treatment
effects data, and derive new results for high-dimensional, sparse multinomial
logistic regression. A simulation study shows our estimator performs very well
in finite samples over a wide range of models. Revisiting the National
Supported Work demonstration data, our method yields accurate estimates and
tight confidence intervals.


title: Analysis of circuit imperfections in BosonSampling

abstract:
  BosonSampling is a problem where a quantum computer offers a provable speedup
over classical computers. Its main feature is that it can be solved with
current linear optics technology, without the need for a full quantum computer.
In this work, we investigate whether an experimentally realistic BosonSampler
can really solve BosonSampling without any fault-tolerance mechanism. More
precisely, we study how the unavoidable errors linked to an imperfect
calibration of the optical elements affect the final result of the computation.
We show that the fidelity of each optical element must be at least $1 -
O(1/n^2)$, where $n$ refers to the number of single photons in the scheme. Such
a requirement seems to be achievable with state-of-the-art equipment.


title:
Electroweak symmetry breaking by dynamically generated masses of quarks
  and leptons

abstract:
  The aim of the thesis is to study models of the electroweak symmetry breaking
caused by dynamically generated masses of quarks and leptons. (1) We perform
the basic analysis whether the main underlying idea, that the masses of only
known fermions can provide the electroweak symmetry breaking, is actually
feasible. For that we elaborate a two-composite-Higgs-doublet model of the
top-quark and neutrino condensation. The model suggests rather large number,
$\mathcal{O}(100)$, of right-handed neutrinos. (2) We analyze the model of
strong Yukawa dynamics where the dynamical fermion mass generation is provided
by exchanges of new elementary massive complex doublet scalar fields. We focus
on solving the coupled Schwinger--Dyson equations for fermion and scalar
self-energies by means of approximative methods. We document that strongly
hierarchical mass spectra can be reproduced. (3) We elaborate the flavor gauge
model where the dynamical fermion mass generation is provided by asymptotically
free non-Abelian self-breaking flavor gauge dynamics. We show that the Majorana
type condensation of right-handed neutrinos in the flavor sextet representation
triggers the complete flavor symmetry breaking. It leads to huge right-handed
neutrino Majorana masses.


title: Representations of Generalized Almost-Jordan algebras

abstract:
  This paper deals with the variety of commutative algebras satisfying one of
the four families of degree four identities found by Carini, Hentzel and
Piacentini-Cattaneo in 1988. We give a characterization of representations and
irreducible modules on these algebras. Our results require that the
characteristic of the ground field be different from 2,3.


title:
Security Enhancement of Biometric Authentication Scheme for Telecare
  Medicine Information Systems with Nonce

abstract:
  Telecare medicine information systems (TMIS) present the platform to deliver
clinical service door to door. The technological advances in mobile computing
are enhancing the quality of healthcare and a user can access these services
using its mobile device. Existing authentication schemes for TMIS are either
vulnerable to attacks or they have higher computational cost. We propose a
biometric based efficient authentication scheme for TMIS which only requires
the computation of the hash and XOR functions.


title:
Nontrivial solutions for a mixed boundary problem for Schr\"odinger
  equations with an external magnetic field

abstract:
  We study the existence of solutions for a class of nonlinear Schr\"odinger
equations involving a magnetic field with mixed Dirichlet-Neumann boundary
conditions. We use Lyusternik-Shnirelman category and the Morse theory to
estimate the number of nontrivial solutions in terms of the topology of the
part of the boundary where the Neumann condition is prescribed.


title:
An Analysis of the 'Blind Variation and Selective Retention' Theory of
  Creativity

abstract:
  Picasso's Guernica sketches continue to provide a fruitful testing ground for
examining and assessing the Blind Variation Selective Retention (BVSR) theory
of creativity. Nonmonotonicity--e.g. as indicated by a lack of similarity of
successive sketches--is not evidence of a selectionist process; Darwin's theory
explains adaptive change, not nonmonotonicity. Although the notion of blindness
originally implied randomness, it now encompasses phenomena that bias idea
generation, e.g. the influence of remote associations on sketch ideas. However,
for a selectionist framework is to be applicable, such biases must be
negligible, otherwise evolutionary change is attributed to those biases, not to
selection. The notion of 'variants' should not be applied to creativity;
without a mechanism of inheritance, there is no basis upon which to delineate,
for example, which sketch ideas are or are not variants of a given sketch idea.
The notion of selective retention is also problematic. Selection provides an
explanation when acquired change is not transmitted; it cannot apply to
Picasso's painting (or other creative acts) because his ideas acquired
modifications as he thought them through that were incorporated into paintings
and viewed by others. The generation of one sketch affects the criteria by
which the next is judged, so sequentially generated sketches cannot be treated
as members of a generation, and selected amongst. Although BVSR is
inappropriate as a theoretical framework for creativity, exploring to what
extent selectionism explains the generation of not just biological form but
masterpieces such as Picasso's Guernica is useful for gaining insight into
creativity.


title: Modelling Probabilistic Wireless Networks

abstract:
  We propose a process calculus to model high level wireless systems, where the
topology of a network is described by a digraph. The calculus enjoys features
which are proper of wireless networks, namely broadcast communication and
probabilistic behaviour. We first focus on the problem of composing wireless
networks, then we present a compositional theory based on a probabilistic
generalisation of the well known may-testing and must-testing pre- orders.
Also, we define an extensional semantics for our calculus, which will be used
to define both simulation and deadlock simulation preorders for wireless
networks. We prove that our simulation preorder is sound with respect to the
may-testing preorder; similarly, the deadlock simulation pre- order is sound
with respect to the must-testing preorder, for a large class of networks. We
also provide a counterexample showing that completeness of the simulation
preorder, with respect to the may testing one, does not hold. We conclude the
paper with an application of our theory to probabilistic routing protocols.


title:
Controlling the nonlinear intracavity dynamics of large He-Ne laser
  gyroscopes

abstract:
  A model based on Lamb's theory of gas lasers is applied to a He-Ne ring laser
gyroscope in order to estimate and remove the laser dynamics contribution from
the rotation measurements. The intensities of the counter-propagating laser
beams exiting one cavity mirror are continuously observed together with a
monitor of the laser population inversion. These observables, once properly
calibrated with a dedicated procedure, allow us to estimate cold cavity and
active medium parameters driving the main part of the nonlinearities of the
system. The parameters identification and noise subtraction procedure has been
verified by means of a Monte Carlo study of the system, and experimentally
tested on the G-Pisa ring laser oriented with the normal to the ring plane
almost parallel to the Earth rotation axis. In this configuration the Earth
rotation-rate provides the maximum Sagnac effect while the contribution of the
orientation error is reduced at minimum. After the subtraction of laser
dynamics by a Kalman filter, the relative systematic errors of G-PISA reduce
from 50 to 5 part in 10^3 and can be attributed to the residual uncertainties
on geometrical scale factor and orientation of the ring.


title: Detection of an outburst one year prior to the explosion of SN 2011ht

abstract:
  Using imaging from the Pan-STARRS1 survey, we identify a precursor outburst
at epochs 287 and 170 days prior to the reported explosion of the purported
Type IIn supernova (SN) 2011ht. In the Pan-STARRS data, a source coincident
with SN 2011ht is detected exclusively in the \zps\ and \yps-bands. An absolute
magnitude of M$_z\simeq$-11.8 suggests that this was an outburst of the
progenitor star. Unfiltered, archival Catalina Real Time Transient survey
images also reveal a coincident source from at least 258 to 138 days before the
main event. We suggest that the outburst is likely to be an intrinsically red
eruption, although we cannot conclusively exclude a series of erratic outbursts
which were observed only in the redder bands by chance. This is only the fourth
detection of an outburst prior to a claimed SN, and lends credence to the
possibility that many more interacting transients have pre-explosion outbursts,
which have been missed by current surveys.


title: STM contrast inversion of the Fe(110) surface

abstract:
  We extend the orbital-dependent electron tunneling model implemented within
the three-dimensional (3D) Wentzel-Kramers-Brillouin (WKB) atom-superposition
approach to simulate spin-polarized scanning tunneling microscopy (SP-STM)
above magnetic surfaces. The tunneling model is based on the electronic
structure data of the magnetic tip and surface obtained from first principles.
Applying our method, we analyze the orbital contributions to the tunneling
current, and study the nature of atomic contrast reversals occurring on
constant-current SP-STM images above the Fe(110) surface. We find an interplay
of orbital-dependent tunneling and spin-polarization effects responsible for
the contrast inversion, and we discuss its dependence on the bias voltage, on
the tip-sample distance, and on the tip orbital composition.


title:
Representations of copointed Hopf algebras arising from the tetrahedron
  rack

abstract:
  We study the copointed Hopf algebras attached to the Nichols algebra of the
affine rack $\Aff(\F_4,\omega)$, also known as tetrahedron rack, and the
2-cocycle -1. We investigate the so-called Verma modules and classify all the
simple modules. We conclude that these algebras are of wild representation type
and not quasitriangular, also we analyze when these are spherical.


title: Koszul determinantal rings and $2\times e$ matrices of linear forms

abstract:
  Let $k$ be an algebraically closed field of characteristic $0$. Let $X$ be a
$2\times e$ matrix of linear forms over a polynomial ring $k[\mathsf{x}_1,
\ldots,\mathsf{x}_n]$ (where $e,n\ge 1$). We prove that the determinantal ring
$R = k[\mathsf{x}_1,\ldots,\mathsf{x}_n]/I_2(X)$ is Koszul if and only if in
the Kronecker-Weierstrass normal form of $X$, the largest length of a nilpotent
block is at most twice the smallest length of a scroll block. As an
application, we classify rational normal scrolls whose all section rings by
natural coordinates are Koszul. This result settles a conjecture due to Conca.


title:
Global Forty-Years Validation of Seasonal Precipitation Forecasts:
  Assessing El Ni\~no-Driven Skill

abstract:
  The skill of seasonal precipitation forecasts is assessed worldwide -grid
point by grid point- for the forty-years period 1961-2000. To this aim, the
ENSEMBLES multi-model hindcast is considered. Although predictability varies
with region, season and lead-time, results indicate that 1) significant skill
is mainly located in the tropics -20 to 40% of the total land areas-, 2)
overall, SON (MAM) is the most (less) skillful season and 3) predictability
does not decrease noticeably from one to four months lead-time -this is so
especially in northern south America and the Malay archipelago, which seem to
be the most skillful regions of the world-. An analysis of teleconnections
revealed that most of the skillful zones exhibit significant teleconnections
with El Ni\~no. Furthermore, models are shown to reproduce similar
teleconnection patterns to those observed, especially in SON -with spatial
correlations of around 0.6 in the tropics-. Moreover, these correlations are
systematically higher for the skillful areas. Our results indicate that the
skill found might be determined to a great extent by the models' ability to
properly reproduce the observed El Ni\~no teleconnections, i.e., the better a
model simulates the El Ni\~no teleconnections, the higher its performance is.


title: Classical Conformal Blocks and Painleve VI

abstract:
  We study the classical c\to \infty limit of the Virasoro conformal blocks. We
point out that the classical limit of the simplest nontrivial null-vector
decoupling equation on a sphere leads to the Painleve VI equation. This gives
the explicit representation of generic four-point classical conformal block in
terms of the regularized action evaluated on certain solution of the Painleve
VI equation. As a simple consequence, the monodromy problem of the Heun
equation is related to the connection problem for the Painleve VI.


title:
On the form factors of local operators in the Bazhanov-Stroganov and
  chiral Potts models

abstract:
  We consider general cyclic representations of the 6-vertex Yang-Baxter
algebra and analyze the associated quantum integrable systems, the
Bazhanov-Stroganov model and the corresponding chiral Potts model on finite
size lattices. We first determine the propagator operator in terms of the
chiral Potts transfer matrices and we compute the scalar product of separate
states (including the transfer matrix eigenstates) as a single determinant
formulae in the framework of Sklyanin's quantum separation of variables. Then,
we solve the quantum inverse problem and reconstruct the local operators in
terms of the separate variables. We also determine a basis of operators whose
form factors are characterized by a single determinant formulae. This implies
that the form factors of any local operator are expressed as finite sums of
determinants. Among these form factors written in determinant form are in
particular those which will reproduce the chiral Potts order parameters in the
thermodynamic limit.

categories: math-ph cond-mat.stat-mech math.MP nlin.SI


title: Divisors on Burniat surfaces

abstract:
  In this short note, we extend the results of [Alexeev-Orlov, 2012] about
Picard groups of Burniat surfaces with $K^2=6$ to the cases of $2\le K^2\le 5$.
We also compute the semigroup of effective divisors on Burniat surfaces with
$K^2=6$. Finally, we construct an exceptional collection on a nonnormal
semistable degeneration of a 1-parameter family of Burniat surfaces with
$K^2=6$.


title:
The Debris Disk Explorer: a balloon-borne coronagraph for observing
  debris disks

abstract:
  The Debris Disk Explorer (DDX) is a proposed balloon-borne investigation of
debris disks around nearby stars. Debris disks are analogs of the Asteroid Belt
(mainly rocky) and Kuiper Belt (mainly icy) in our Solar System. DDX will
measure the size, shape, brightness, and color of tens of disks. These
measurements will enable us to place the Solar System in context. By imaging
debris disks around nearby stars, DDX will reveal the presence of perturbing
planets via their influence on disk structure, and explore the physics and
history of debris disks by characterizing the size and composition of disk
dust.
  The DDX instrument is a 0.75-m diameter off-axis telescope and a coronagraph
carried by a stratospheric balloon. DDX will take high-resolution,
multi-wavelength images of the debris disks around tens of nearby stars. Two
flights are planned; an overnight test flight within the United States followed
by a month-long science flight launched from New Zealand. The long flight will
fully explore the set of known debris disks accessible only to DDX. It will
achieve a raw contrast of 10^-7, with a processed contrast of 10^-8. A
technology benefit of DDX is that operation in the near-space environment will
raise the Technology Readiness Level of internal coronagraphs, deformable
mirrors, and wavefront sensing and control, all potentially needed for a future
space-based telescope for high-contrast exoplanet imaging.


title:
Searching for AdS_3 waves and Asymptotically Lifshitz black holes in
  R^3-NMG

abstract:
  In this paper we consider the structure of the $AdS_3$ vacua in $R^3$
expansion of the New Massive Gravity ($R^3$-NMG). We obtain the degeneracies of
the $AdS_3$ vacua at several points of the parametric space. Additionally,
following a specific analysis we show that $AdS_3$ wave solutions are present.
Using these wave solutions, we single out two special points of the parametric
space for which logarithmic terms appear in the solutions. The first one is a
point at which the effective mass of the wave profile which is interpreted as a
scalar mode, completely saturates the Breitenlohner-Freedman bound of the
$AdS_3$ space in which the wave is propagating. The second special point is a
point at which the central charge of the theory vanishes. Furthermore, we
investigate the possibility of asymptotically Lifshitz black solutions to be
present in the three-dimensional $R^3$-NMG. We derive analytically the Lifshitz
vacua considering specific relations between the mass parameters of $R^3$-NMG.
A certain polynomial equation arises at the first special point where solutions
with logarithmic fall-off in the $AdS_3$ space appear. Solving this polynomial
equation, we obtain the values of the dynamical exponent $z$ which correspond
to possible asymptotically Lifshitz black hole solutions. However, it is shown
that asymptotically Lifshitz black solutions do not exist in the
three-dimensional $R^3$-NMG for a specific ansatz of the black hole metric.


title: Simulating defect textures on coalescing nematic shells

abstract:
  Two nematic shells brought in contact coalesce in order to reduce their
interfacial tension. This process proceeds through the creation of a liquid
neck-like bridge through which the encapsulated fluid flows. Following this
topological transition, We study the defect textures as the combined shell
shape evolves. Varying the sizes of the shells, we perform a quasistatic
investigation of the director field and the defect valence on the doublet.
Regimes are found where positive and negative defects exist due to the large
negative Gaussian curvature at the neck. Using large scale computer
simulations, we determine how annihilating defect pairs on coalescing shells
are selected, and the stage of coalescence at which annihilation occurs.


title:
The Spectrum of Non-Local Discrete Schroedinger Operators with a
  delta-Potential

abstract:
  The behaviour of the spectral edges (embedded eigenvalues and resonances) is
discussed at the two ends of the continuous spectrum of non-local discrete
Schr\"odinger operators with a $\delta$-potential. These operators arise by
replacing the discrete Laplacian by a strictly increasing $C^1$-function of the
discrete Laplacian. The dependence of the results on this function and the
lattice dimension are explicitly derived. It is found that while in the case of
the discrete Schr\"odinger operator these behaviours are the same no matter
which end of the continuous spectrum is considered, an asymmetry occurs for the
non-local cases. A classification with respect to the spectral edge behaviour
is also offered.


title:
Emergent granularity and pseudogap near the superconductor-insulator
  transition

abstract:
  In two dimensions there is a direct superconductor-to-insulator quantum phase
transition driven by increasing disorder. We elucidate, using a combination of
inhomogeneous mean field theory and quantum Monte Carlo techniques, the nature
of the phases and the mechanism of the transition. We make several testable
predictions specifically for local spectroscopic probes. With increasing
disorder, the system forms superconducting blobs on the scale of the coherence
length embedded in an insulating matrix. In the superconducting state, the
phases on the different blobs are coherent across the system whereas in the
insulator long range phase coherence is disrupted by quantum fluctuations. As a
consequence of this emergent granularity, we show that the single-particle
energy gap in the density of states survives across the transition, but
coherence peaks exist only in the superconductor. A characteristic pseudogap
persists above the critical disorder and critical temperature, in contrast to
conventional theories. Surprisingly, the insulator has a two-particle gap scale
that vanishes at the SIT, despite a robust single-particle gap.


title: Normality condition in elasticity

abstract:
  Strong local minimizers with surfaces of gradient discontinuity appear in
variational problems when the energy density function is not rank-one convex.
In this paper we show that stability of such surfaces is related to stability
outside the surface via a single jump relation that can be regarded as
interchange stability condition. Although this relation appears in the setting
of equilibrium elasticity theory, it is remarkably similar to the well known
normality condition which plays a central role in the classical plasticity
theory.


title:
The rate of linear convergence of the Douglas-Rachford algorithm for
  subspaces is the cosine of the Friedrichs angle

abstract:
  The Douglas-Rachford splitting algorithm is a classical optimization method
that has found many applications. When specialized to two normal cone
operators, it yields an algorithm for finding a point in the intersection of
two convex sets. This method for solving feasibility problems has attracted a
lot of attention due to its good performance even in nonconvex settings.
  In this paper, we consider the Douglas-Rachford algorithm for finding a point
in the intersection of two subspaces. We prove that the method converges
strongly to the projection of the starting point onto the intersection.
Moreover, if the sum of the two subspaces is closed, then the convergence is
linear with the rate being the cosine of the Friedrichs angle between the
subspaces. Our results improve upon existing results in three ways: First, we
identify the location of the limit and thus reveal the method as a best
approximation algorithm; second, we quantify the rate of convergence, and
third, we carry out our analysis in general (possibly infinite-dimensional)
Hilbert space. We also provide various examples as well as a comparison with
the classical method of alternating projections.


title: Preinjective subfactors of preinjective Kronecker modules

abstract:
  Using a representation theoretical approach we give an explicit numerical
characterization in terms of Kronecker invariants of the subfactor relation
between two preinjective (and dually preprojective) Kronecker modules,
describing explicitly a so called linking module as well. Preinjective
(preprojective) Kronecker modules correspond to matrix pencils having only
minimal indices for columns (respectively for rows). Thus our result gives a
solution to the subpencil problem in these cases (including the completion),
moreover the required computations are straightforward and can be carried out
easily (both for checking the subpencil relation and constructing the
completion pencils based on the linking module). We showcase our method by
carrying out the computations on an explicit example.


title:
Parity violation in proton-proton scattering from chiral effective field
  theory

abstract:
  We present a calculation of the parity-violating longitudinal asymmetry in
proton-proton scattering. The calculation is performed in the framework of
chiral effective field theory which is applied systematically to both the
parity-conserving and parity-violating interactions. The asymmetry is
calculated up to next-to-leading order in the parity-odd nucleon-nucleon
potential. At this order the asymmetry depends on two parity-violating
low-energy constants: the weak pion-nucleon coupling constant $h_\pi$ and one
four-nucleon contact coupling. By comparison with the existing data, we obtain
a rather large range for $h_\pi= (1.1\pm 2)\cdot 10^{-6}$. This range is
consistent with theoretical estimations and experimental limits, but more data
are needed to pin down a better constrained value. We conclude that an
additional measurement of the asymmetry around 125 MeV lab energy would be
beneficial to achieve this goal.


title:
Distilling the Essence of an Evolutionary Process and Implications for a
  Formal Description of Culture

abstract:
  It has been proposed that, since the origin of life and the ensuing evolution
of biological species, a second evolutionary process has appeared on our
planet. It is the evolution of culture-e.g., ideas, beliefs, and artifacts.
Does culture evolve in the same genuine sense as biological life? And if so,
does it evolve through natural selection, or by some other means? Why does no
other species remotely approach the degree of cultural complexity of humans?
These questions lie at the foundation of who we are and what makes our lives
meaningful. Although much research has been done on how selective pressures
operating at the biological level affect cognition and culture, little research
has focused on culture as an evolutionary process in its own right. Like
biological forms, cultural forms-ideas, attitudes, artifacts, mannerisms,
etc.-incrementally adapt to the constraints and affordances of their
environment through descent with modification. In some respects culture appears
to be Darwinian, i.e., a process of differential replication and selection
amongst randomly generated variants. This suggests that knowledge of biological
evolution can be put to use to gain insight into culture. However, attempts to
apply Darwinian theory to culture have not yielded the kind of unifying
framework for the social sciences that it provided for the biological sciences,
largely because of the nonrandom manner in which the mind-the hub of cultural
change-generates and assimilates novelty. This paper investigates how and when
humans became capable of supporting culture, and what previously held it back,
focusing on how we attained the creative powers we now possess. To invent in
the strategic, intuitive manner characteristic of humans requires a cognitive
architecture that supports the capacity to spontaneously adapt concepts to new
circumstances and merge them together to conceptualize new situations.


title: SEFE with No Mapping via Large Induced Outerplane Graphs in Plane Graphs

abstract:
  We show that every $n$-vertex planar graph admits a simultaneous embedding
with no mapping and with fixed edges with any $(n/2)$-vertex planar graph. In
order to achieve this result, we prove that every $n$-vertex plane graph has an
induced outerplane subgraph containing at least $n/2$ vertices. Also, we show
that every $n$-vertex planar graph and every $n$-vertex planar partial 3-tree
admit a simultaneous embedding with no mapping and with fixed edges.


title:
Temporal-Difference Learning to Assist Human Decision Making during the
  Control of an Artificial Limb

abstract:
  In this work we explore the use of reinforcement learning (RL) to help with
human decision making, combining state-of-the-art RL algorithms with an
application to prosthetics. Managing human-machine interaction is a problem of
considerable scope, and the simplification of human-robot interfaces is
especially important in the domains of biomedical technology and rehabilitation
medicine. For example, amputees who control artificial limbs are often required
to quickly switch between a number of control actions or modes of operation in
order to operate their devices. We suggest that by learning to anticipate
(predict) a user's behaviour, artificial limbs could take on an active role in
a human's control decisions so as to reduce the burden on their users.
Recently, we showed that RL in the form of general value functions (GVFs) could
be used to accurately detect a user's control intent prior to their explicit
control choices. In the present work, we explore the use of temporal-difference
learning and GVFs to predict when users will switch their control influence
between the different motor functions of a robot arm. Experiments were
performed using a multi-function robot arm that was controlled by muscle
signals from a user's body (similar to conventional artificial limb control).
Our approach was able to acquire and maintain forecasts about a user's
switching decisions in real time. It also provides an intuitive and reward-free
way for users to correct or reinforce the decisions made by the machine
learning system. We expect that when a system is certain enough about its
predictions, it can begin to take over switching decisions from the user to
streamline control and potentially decrease the time and effort needed to
complete tasks. This preliminary study therefore suggests a way to naturally
integrate human- and machine-based decision making systems.


title: Chiral Symmetry Breaking: To Probe Anisotropy and Magnetic Field in QGP

abstract:
  We discuss the (spontaneous) chiral symmetry breaking in a strongly coupled
anisotropic quark-gluon plasma (QGP) in the presence of the magnetic field,
using holography. The physical quantities related to the chiral symmetry
breaking (m;B_c) distinguish between the effects of the anisotropy and magnetic
field on the plasma. Anisotropy affects the system similar to the temperature
and for its larger values heavier quarks can live in the QGP without getting
condensed. Raising the anisotropy in the system will also increase the value of
the critical magnetic field, B_c, at which the spontaneous chiral symmetry
breaking happens. Both of these growths are even more when the magnetic field
is applied perpendicular to the anisotropy direction. Such behaviour persists
in the high temperature limit where the temperature is kept fixed. However,
when the entropy density is held fixed, as one increases the anisotropy,
lighter mesons melt when the magnetic field is applied along the anisotropy
direction, in contrast to when the magnetic field is perpendicular to the
anisotropy direction.


title: Theoretical Studies of Superconductor-Insulator Transitions

abstract:
  In this article we study superconductor-insulator transitions within the
general framework of an attractive Hubbard model. This is a well-defined model
of s-wave superconductivity which permits different tuning parameters (disorder
and field). Furthermore, it allows a comparison of various analytical and
computational approaches in order to gain a complete understanding of the
various effects of amplitude and phase fluctuations. We present a systematic
pedagogical approach, aiming to equip the lay reader with enough apparatus to
be able to understand the numerical calculations, reproduce some of the simpler
results, and be able to tackle future problems related to inhomogeneous phases.
We go into considerable detail on mean-field theory (MFT) and the Bogoliubov-de
Gennes (BdG) approach, as these are a first line of attack which can capture
much of the physics, but we also outline cases where this fails to capture
phase fluctuations and more sophisticated Quantum Monte Carlo (QMC)
calculations are necessary. We discuss the behavior of many observables,
including densities of states, superfluid stiffness, and dynamical
conductivity, for the disorder-tuned superconductor-insulator transition. We
also discuss SITs tuned by parallel magnetic field, which are quite different
due to pairbreaking.


title:
Tractable Simulation of Error Correction with Honest Approximations to
  Realistic Fault Models

abstract:
  In previous work, we proposed a method for leveraging efficient classical
simulation algorithms to aid in the analysis of large-scale fault tolerant
circuits implemented on hypothetical quantum information processors. Here, we
extend those results by numerically studying the efficacy of this proposal as a
tool for understanding the performance of an error-correction gadget
implemented with fault models derived from physical simulations. Our approach
is to approximate the arbitrary error maps that arise from realistic physical
models with errors that are amenable to a particular classical simulation
algorithm in an "honest" way; that is, such that we do not underestimate the
faults introduced by our physical models. In all cases, our approximations
provide an "honest representation" of the performance of the circuit composed
of the original errors. This numerical evidence supports the use of our method
as a way to understand the feasibility of an implementation of quantum
information processing given a characterization of the underlying physical
processes in experimentally accessible examples.


title:
Parameterized Exact and Approximation Algorithms for Maximum $k$-Set
  Cover and Related Satisfiability Problems

abstract:
  Given a family of subsets $\mathcal S$ over a set of elements~$X$ and two
integers~$p$ and~$k$, Max k-Set Cover consists of finding a subfamily~$\mathcal
T \subseteq \mathcal S$ of cardinality at most~$k$, covering at least~$p$
elements of~$X$. This problem is W[2]-hard when parameterized by~$k$, and FPT
when parameterized by $p$. We investigate the parameterized approximability of
the problem with respect to parameters~$k$ and~$p$. Then, we show that Max
Sat-k, a satisfiability problem generalizing Max k-Set Cover, is also FPT with
respect to parameter~$p$.


title:
Plasmonic angular momentum on metal-dielectric nano-wedges in a
  sectorial indefinite metamaterial

abstract:
  We present an analytical study to the structure-modulated plasmonic angular
momentum trapped on periodic metal-dielectric nano-wedges in the core region of
a sectorial indefinite metamaterial. Employing a transfer-matrix calculation
and a conformal-mapping technique, our theory is capable of dealing with
realistic configurations of arbitrary sector numbers and rounded wedge tips. We
demonstrate that in the deep-subwavelength regime strong electric field
carrying high azimuthal variation can exist within only ten-nanometer length
scale close to the structural center, and is naturally bounded by a
characteristic radius of the order of hundred-nanometer away from the center.
These extreme confining properties suggest that the structure under
investigation may be superior to the conventional metal-dielectric waveguides
or cavities in terms of nanoscale photonic manipulation.


title: Robustness of Network Measures to Link Errors

abstract:
  In various applications involving complex networks, network measures are
employed to assess the relative importance of network nodes. However, the
robustness of such measures in the presence of link inaccuracies has not been
well characterized. Here we present two simple stochastic models of false and
missing links and study the effect of link errors on three commonly used node
centrality measures: degree centrality, betweenness centrality, and dynamical
importance. We perform numerical simulations to assess robustness of these
three centrality measures. We also develop an analytical theory, which we
compare with our simulations, obtaining very good agreement.

categories: physics.soc-ph cond-mat.stat-mech cs.SI q-bio.MN


title: Higher symmetry and gapped phases of gauge theories

abstract:
  We study topological field theory describing gapped phases of gauge theories
where the gauge symmetry is partially Higgsed and partially confined. The TQFT
can be formulated both in the continuum and on the lattice and generalizes
Dijkgraaf-Witten theory by replacing a finite group by a finite 2-group. The
basic field in this TQFT is a 2-connection on a principal 2-bundle. We classify
topological actions for such theories as well as loop and surface observables.
When the topological action is trivial, the TQFT is related to a
Dijkgraaf-Witten theory by electric-magnetic duality, but in general it is
distinct. We propose the existence of new phases of matter protected by higher
symmetry.


title: An explanatory evo-devo model for the developmental hourglass

abstract:
  The "developmental hourglass" describes a pattern of increasing morphological
divergence towards earlier and later embryonic development, separated by a
period of significant conservation across distant species (the "phylotypic
stage"). Recent studies have found evidence in support of the hourglass effect
at the genomic level. For instance, the phylotypic stage expresses the oldest
and most conserved transcriptomes. However, the regulatory mechanism that
causes the hourglass pattern remains an open question. Here, we use an
evolutionary model of regulatory gene interactions during development to
identify the conditions under which the hourglass effect can emerge in a
general setting. The model focuses on the hierarchical gene regulatory network
that controls the developmental process, and on the evolution of a population
under random perturbations in the structure of that network. The model
predicts, under fairly general assumptions, the emergence of an hourglass
pattern in the structure of a temporal representation of the underlying gene
regulatory network. The evolutionary age of the corresponding genes also
follows an hourglass pattern, with the oldest genes concentrated at the
hourglass waist. The key behind the hourglass effect is that developmental
regulators should have an increasingly specific function as development
progresses. Analysis of developmental gene expression profiles from Drosophila
melanogaster and Arabidopsis thaliana provide consistent results with our
theoretical predictions.


title: Increasing thermal rectification: Effects of long range interactions

abstract:
  In this paper, we study the effects of the interparticle interaction range on
heat flow. We show that, by increasing the interaction range, we may amplify
the thermal conductivity and even change the regime of heat transport. More
importantly, considering a crucial problem of phononics, namely, the search of
a suitable thermal diode, we investigate the range effects in some graded
systems in which thermal rectification is a ubiquitous phenomenon. In such
graded models, we show that long range interactions may significatively
increase the rectification power and may avoid its decay with the system size,
thus solving relevant problems of the usual proposals of rectifiers. Our
results indicate that graded materials are genuine candidates for the actual
fabrication of thermal diodes.


title: State-dependent linear-optical qubit amplifier

abstract:
  We propose a linear-optical setup for heralded qubit amplification with
tunable output qubit fidelity. We study its success probability as a function
of output qubit fidelity showing that at the expense of lower fidelity, the
setup can considerably increase probability of successful operation. These
results are subsequently applied in a proposal for state dependent qubit
amplification. Similarly to state-dependent quantum cloning, the a priori
information about the input state allows to optimize the qubit amplification
procedure to obtain better fidelity versus success probability trade-off.


title:
Nonequilibrium Quantum Phase Transitions in the XY model: comparison of
  unitary time evolution and reduced density matrix approaches

abstract:
  We study nonequilibrium quantum phase transitions in XY spin 1/2 chain using
the $C^*$ algebra. We show that the well-known quantum phase transition at
magnetic field $h = 1$ persists also in the nonequilibrium setting as long as
one of the reservoirs is set to absolute zero temperature. In addition, we find
nonequilibrium phase transitions associated to imaginary part of the
correlation matrix for any two different temperatures of the reservoirs at $h =
1$ and $h = h_{\rm c} \equiv|1-\gamma^2|$, where $\gamma$ is the anisotropy and
$h$ the magnetic field strength. In particular, two nonequilibrium quantum
phase transitions coexist at $h=1$. In addition we also study the quantum
mutual information in all regimes and find a logarithmic correction of the area
law in the nonequilibrium steady state independent of the system parameters. We
use these nonequilibrium phase transitions to test the utility of two models of
reduced density operator, namely Lindblad mesoreservoir and modified Redfield
equation. We show that the nonequilibrium quantum phase transition at $h = 1$
related to the divergence of magnetic susceptibility is recovered in the
mesoreservoir approach, whereas it is not recovered using the Redfield master
equation formalism. However none of the reduced density operator approaches
could recover all the transitions observed by the $C^*$ algebra. We also study
thermalization properties of the mesoreservoir approach.


title: Perverse sheaves on semiabelian varieties

abstract:
  We give a Tannakian description for categories of l-adic perverse sheaves on
semiabelian varieties which combines a construction of Gabber and Loeser for
algebraic tori with a generic vanishing theorem for the cohomology of
constructible sheaves on abelian varieties. As an application we explain how
the arising Tannaka groups on abelian varieties can be studied in terms of
semiabelian degenerations via the functor of nearby cycles.


title: Dissipation, interaction and relative entropy

abstract:
  Many thermodynamic relations involve inequalities, with equality if a process
does not involve dissipation. In this article we provide equalities in which
the dissipative contribution is shown to involve the relative entropy (a.k.a.
Kullback-Leibler divergence). The processes considered are general time
evolutions both in classical and quantum mechanics, and the initial state is
sometimes thermal, sometimes partially so. As an application, the relative
entropy is related to transport coefficients.


title: Molecular state $N\Xi$ in the coupled-channel formalism

abstract:
  The relativistic six-quark equations for the molecule $N\Xi$ are found in the
dispersion relation technique. The relativistic six-quark amplitudes of the
hexaquark including the quarks of three flavors ($u$, $d$, $s$) are calculated.
The pole of these amplitudes determines the mass of $N\Xi$ state $M=2252\,
MeV$. The binding energy is equal to $3\, MeV$.


title: Astrobiology: An Astronomer's Perspective

abstract:
  In this review we explore aspects of the field of astrobiology from an
astronomical viewpoint. We therefore focus on the origin of life in the context
of planetary formation, with additional emphasis on tracing the most abundant
volatile elements, C, H, O, and N that are used by life on Earth. We first
explore the history of life on our planet and outline the current state of our
knowledge regarding the delivery of the C, H, O, N elements to the Earth. We
then discuss how astronomers track the gaseous and solid molecular carriers of
these volatiles throughout the process of star and planet formation. It is now
clear that the early stages of star formation fosters the creation of water and
simple organic molecules with enrichments of heavy isotopes. These molecules
are found as ice coatings on the solid materials that represent microscopic
beginnings of terrestrial worlds. Based on the meteoritic and cometary record,
the process of planet formation, and the local environment, lead to additional
increases in organic complexity. The astronomical connections towards this
stage are only now being directly made. Although the exact details are
uncertain, it is likely that the birth process of star and planets likely leads
to terrestrial worlds being born with abundant water and organics on the
surface.


title: Self-affine sets and the continuity of subadditive pressure

abstract:
  The affinity dimension is a number associated to an iterated function system
of affine maps, which is fundamental in the study of the fractal dimensions of
self-affine sets. De-Jun Feng and the author recently solved a folklore open
problem, by proving that the affinity dimension is a continuous function of the
defining maps. The proof also yields the continuity of a topological pressure
arising in the study of random matrix products. I survey the definition,
motivation and main properties of the affinity dimension and the associated SVF
topological pressure, and give a proof of their continuity in the special case
of ambient dimension two.


title: Ballooning Spiders: The Case for Electrostatic Flight

abstract:
  We consider general aspects of the physics underlying the flight of Gossamer
spiders, also known as ballooning spiders. We show that existing observations
and the physics of spider silk in the presence of the Earth's static
atmospheric electric field indicate a potentially important role for
electrostatic forces in the flight of Gossamer spiders. A compelling example is
analyzed in detail, motivated by the observed "unaccountable rapidity" in the
launching of such spiders from H.M.S. Beagle, recorded by Charles Darwin during
his famous voyage.


title: Sub-Doppler Cooling of Neutral Atoms in a Grating Magneto-Optical Trap

abstract:
  The grating magneto-optical trap (GMOT) requires only one beam and three
planar diffraction gratings to form a cloud of cold atoms above the plane of
the diffractors. Despite the complicated polarization arrangement, we
demonstrate sub-Doppler cooling of 87Rb atoms to a temperature of 7.6(0.6) uK
through a multi-stage, far-detuned GMOT in conjunction with optical molasses. A
decomposition of the electric field into polarization components for this
geometry does not yield a mapping onto standard sub-Doppler laser-cooling
configurations. With numerical simulations, we find that the polarization
composition of the GMOT optical field, which includes sigma- and pi-polarized
light, does produce sub-Doppler temperatures.


title: Infrared Laboratory Oscillator Strengths of Fe I in the H-Band

abstract:
  We report experimental oscillator strengths for 28 infrared Fe I transitions,
for which no previous experimental values exist. These transitions were
selected to address an urgent need for oscillator strengths of lines in the
H-band (between 1.4 um and 1.7 um) required for the analysis of spectra
obtained from the Sloan Digital Sky Survey (SDSS-III) Apache Point Galactic
Evolution Experiment (APOGEE). Upper limits have been placed on the oscillator
strengths of an additional 7 transitions, predicted to be significant by
published semi-empirical calculations, but not observed to be so.


title:
Local convergence analysis of Inexact Newton method with relative
  residual error tolerance under majorant condition in Riemannian Manifolds

abstract:
  A local convergence analysis of Inexact Newton's method with relative
residual error tolerance for finding a singularity of a differentiable vector
field defined on a complete Riemannian manifold, based on majorant principle,
is presented in this paper. We prove that under local assumptions, the inexact
Newton method with a fixed relative residual error tolerance converges Q
-linearly to a singularity of the vector field under consideration. Using this
result we show that the inexact Newton method to find a zero of an analytic
vector field can be implemented with a fixed relative residual error tolerance.
In the absence of errors, our analysis retrieve the classical local theorem on
the Newton method in Riemannian context.


title:
Functional derivatives applied to error propagation of uncertainties in
  topography to large-aperture scintillometer-derived heat fluxes

abstract:
  Scintillometer measurements allow for estimations of the refractive index
structure parameter $C_n^2$ over large areas in the atmospheric surface layer.
Turbulent fluxes of heat and momentum are inferred through coupled sets of
equations derived from the Monin--Obukhov similarity hypothesis.
One-dimensional sensitivity functions have been produced that relate the
sensitivity of heat fluxes to uncertainties in single values of beam height
over flat terrain. However, real field sites include variable topography. We
develop here, using functional derivatives, the first analysis of the
sensitivity of scintillometer-derived sensible heat fluxes to uncertainties in
spatially distributed topographic measurements. Sensitivity is shown to be
concentrated in areas near the center of the beam path and where the underlying
topography is closest to the beam height. Relative uncertainty contributions to
the sensible heat flux from uncertainties in topography can reach 20\,\% of the
heat flux in some cases. Uncertainty may be greatly reduced by focusing
accurate topographic measurements in these specific areas. A~new
two-dimensional variable terrain sensitivity function is developed for
quantitative error analysis. This function is compared with the previous
one-dimensional sensitivity function for the same measurement strategy over
flat terrain. Additionally, a~new method of solution to the set of coupled
equations is produced that eliminates computational error.


title:
Estimates of the Cross Section of the Production of Z Boson and J/{\psi}
  at the LHC

abstract:
  We calculate the leading order cross section for the associated production of
Z and J/{\psi}. Processes that include associated production of electroweak
bosons and heavy quarlonium can give valuable insight to the production
mechanism of quarkonia. We conclude that this process is accessible by the LHC
statistics.


title: Laurent cancellation for rings of transcendence degree one

abstract:
  If $R$ is an integral domain and $A$ is an $R$-algebra, then $A$ has the {\it
Laurent cancellation property over $R$} if $A^{[\pm n]}\cong_RB^{[\pm n]}$
implies $A\cong_RB$ ($n\ge 0$ and $B$ an $R$-algebra). Here, $A^{[\pm n]}$
denotes the ring of Laurent polynomials in $n$ variables over $A$. Our main
result (Thm. 4.3) is that, if the transcendence degree of $A$ over $R$ is one,
then $A$ has the Laurent cancellation property. The proof uses the
characterization of Laurent polynomial rings given in Thm. 3.2.


title:
Quasi-fixed point scenarios and the Higgs mass in the E6 inspired SUSY
  models

abstract:
  We analyse the two-loop renormalization group (RG) flow of the gauge and
Yukawa couplings within the E6 inspired supersymmetric (SUSY) models with extra
U(1)_{N} gauge symmetry under which right-handed neutrinos have zero charge. In
these models single discrete \tilde{Z}^{H}_2 symmetry forbids the tree-level
flavor-changing transitions and the most dangerous baryon and lepton number
violating operators. We consider two different scenarios A and B that involve
extra matter beyond the MSSM contained in three and four 5+\overline{5}
representations of SU(5) respectively plus three SU(5) singlets which carry
U(1)_{N} charges. In the scenario A the measured values of the SU(2)_W and
U(1)_Y gauge couplings lie near the fixed points of the RG equations. In the
scenario B the contribution of two--loop corrections spoils the unification of
gauge couplings resulting in the appearance of the Landau pole below the Grand
Unification scale M_X. The solutions for the Yukawa couplings also approach the
quasi fixed points with increasing their values at the scale M_X. We calculate
the two--loop upper bounds on the lightest Higgs boson mass in the vicinity of
these quasi fixed points and compare the results of our analysis with the
corresponding ones in the NMSSM. In all these cases the theoretical
restrictions on the SM--like Higgs boson mass are rather close to 125 GeV.


title:
On a family of surfaces of general type attached to abelian fourfolds
  and the Weyl group W(E_6)

abstract:
  We study a family of surfaces of general type that arises from the
intersections of two translates of the theta divisor on a principally polarized
complex abelian fourfold. In particular we determine the N\'eron-Severi
lattices of these surfaces and show that for a general abelian fourfold the
monodromy group of the associated variation of Hodge structures is a subgroup
of index at most two in the Weyl group W(E_6), whereas for a Jacobian variety
it degenerates to a subgroup of the symmetric group S_6.


title:
Hypothesis testing in the presence of multiple samples under density
  ratio models

abstract:
  This paper presents a hypothesis testing method given independent samples
from a number of connected populations. The method is motivated by a forestry
project for monitoring change in the strength of lumber. Traditional practice
has been built upon nonparametric methods which ignore the fact that these
populations are connected. By pooling the information in multiple samples
through a density ratio model, the proposed empirical likelihood method leads
to a more efficient inference and therefore reduces the cost in applications.
The new test has a classical chi-square null limiting distribution. Its power
function is obtained under a class of local alternatives. The local power is
found increased even when some underlying populations are unrelated to the
hypothesis of interest. Simulation studies confirm that this test has better
power properties than potential competitors, and is robust to model
misspecification. An application example to lumber strength is included.


title: Overlap Cycles for Permutations: Necessary and Sufficient Conditions

abstract:
  Universal cycles are generalizations of de Bruijn cycles and Gray codes that
were introduced originally by Chung, Diaconis, and Graham in 1992. They have
been developed by many authors since, for various combinatorial objects such as
strings, subsets, permutations, partitions, vector spaces, and designs. One
generalization of universal cycles, which require almost complete overlap of
consecutive words, is $s$-overlap cycles, which relax such a constraint. In
this paper we study permutations and some closely related class of strings,
namely juggling sequences and functions. We prove the existence of $s$-overlap
cycles for these objects, as they do not always lend themselves to the
universal cycle structure.


title: Adaptive Genetic Algorithm for Crystal Structure Prediction

abstract:
  We present a genetic algorithm (GA) for structural search that combines the
speed of structure exploration by classical potentials with the accuracy of
density functional theory (DFT) calculations in an adaptive and iterative way.
This strategy increases the efficiency of the DFT-based GA by several orders of
magnitude. This gain allows considerable increase in size and complexity of
systems that can be studied by first principles. The method's performance is
illustrated by successful structure identifications of complex binary and
ternary inter-metallic compounds with 36 and 54 atoms per cell, respectively.
The discovery of a multi-TPa Mg-silicate phase with unit cell containing up to
56 atoms is also reported. Such phase is likely to be an essential component of
terrestrial exoplanetary mantles.


title:
Scattering lengths of Nambu-Goldstone bosons off $D$ mesons and
  dynamically generated heavy-light mesons

abstract:
  Recent lattice QCD simulations of the scattering lengths of Nambu-Goldstone
bosons off the $D$ mesons are studied using unitary chiral perturbation theory.
We show that the Lattice QCD data are better described in the covariant
formulation than in the heavy-meson formulation. The $D^*_{s0}(2317)$ can be
dynamically generated from the coupled-channels $DK$ interaction without
\textit{a priori} assumption of its existence. A new renormalization scheme is
proposed which manifestly satisfies chiral power counting rules and has
well-defined behavior in the infinite heavy-quark mass limit. Using this scheme
we predict the heavy-quark spin and flavor symmetry counterparts of the
$D^*_{s0}(2317)$.


title:
Modeling the Role of Context Dependency in the Recognition and
  Manifestation of Entrepreneurial Opportunity

abstract:
  The paper uses the SCOP theory of concepts to model the role of environmental
context on three levels of entrepreneurial opportunity: idea generation, idea
development, and entrepreneurial decision. The role of contextual-fit in the
generation and development of ideas is modeled as the collapse of their
superposition state into one of the potential states that composes this
superposition. The projection of this collapsed state on the socio-economic
basis results in interference of the developed idea with the perceptions of the
supporting community, undergoing an eventual collapse for an entrepreneurial
decision that reflects the shared vision of its stakeholders. The developed
idea may continue to evolve due to continuous or discontinuous changes in the
environment. The model offers unique insights into the effects of external
influences on entrepreneurial decisions.


title: Discreteness Of Curved Space-Time From GUP

abstract:
  Diverse theories of Quantum Gravity expect modification of the Heisenberg
Uncertainty Principle near the Planck scale to a so-called Generalized
Uncertainty Principle.It was shown by some authors that the Generalized
uncertainty principle gives rise to corrections to Schrodinger,Klien-Gordon and
Dirac equations.By solving the Generalized uncertainty principle corrected
equations,the authors arrived at quantization not only of energy but also of
box length,area and volume. We extend the above result to the case of curved
Space-Time(Schwarzschild metric). We showed that we arrived at the Quantization
of Space by solving Dirac equation with Generalized uncertainty principle in
this metric.


title:
Cosmology with non-minimal derivative couplings: perturbation analysis
  and observational constraints

abstract:
  We perform a combined perturbation and observational investigation of the
scenario of non-minimal derivative coupling between a scalar field and
curvature. First we extract the necessary condition that ensures the absence of
instabilities, which is fulfilled more sufficiently for smaller coupling
values. Then using Type Ia Supernovae (SNIa), Baryon Acoustic Oscillations
(BAO), and Cosmic Microwave Background (CMB) observations, we show that,
contrary to its significant effects on inflation, the non-minimal derivative
coupling term has a negligible effect on the universe acceleration, since it is
driven solely by the usual scalar-field potential. Therefore, the scenario can
provide a unified picture of early and late time cosmology, with the
non-minimal derivative coupling term responsible for inflation, and the usual
potential responsible for late-time acceleration. Additionally, the fact that
the necessary coupling term does not need to be large, improves the model
behavior against instabilities.


title: A constructive approach to triangular trigonometric patches

abstract:
  We construct a constrained trivariate extension of the univariate normalized
B-basis of the vector space of trigonometric polynomials of arbitrary (finite)
order n defined on any compact interval [0,\alpha], where \alpha is a fixed
(shape) parameter in (0,\pi). Our triangular extension is a normalized linearly
independent constrained trivariate trigonometric function system of dimension
3n(n+1)+1 that spans the same vector space of functions as the constrained
trivariate extension of the canonical basis of truncated Fourier series of
order n over [0,\alpha]. Although the explicit general basis transformation is
yet unknown, the coincidence of these vector spaces is proved by means of an
appropriate equivalence relation. As a possible application of our triangular
extension, we introduce the notion of (rational) triangular trigonometric
patches of order n and of singularity free parametrization that could be used
as control point based modeling tools in CAGD.


title: Criteria for irreducibility of mod p representations of Frey curves

abstract:
  Let K be a totally real Galois number field and let A be a set of elliptic
curves over K. We give sufficient conditions for the existence of a finite
computable set of rational primes P such that for p not in P and E in A, the
representation on E[p] is irreducible. Our sufficient conditions are often
satisfied for Frey elliptic curves associated to solutions of Diophantine
equations; in that context, the irreducibility of the mod p representation is a
hypothesis needed for applying level-lowering theorems. We illustrate our
approach by improving on an existing result for Fermat-type equations of
signature (13, 13, p).


title: Energetic consequences of flux emergence

abstract:
  When magnetic field in the solar convection zone buoyantly rises to pierce
the visible solar surface (photosphere), the atmosphere (corona) above this
surface must respond in some way. One response of the coronal field to
photospheric forcing is the creation of stress in the magnetic field,
generating large currents and storing magnetic free energy. Using a topological
model of the coronal magnetic field we will quantify this free energy. We find
the free energy just prior to major flares in active regions to be between 30%
and 50% of the potential field energy. In a second way, the coronal field may
topologically restructure to form new magnetic connections with newly emerged
fields. We use our topological model to quantify the rapid restructuring in the
case of solar flare and coronal mass ejections, finding that between 1% and 10%
of total active region flux is exchanged. Finally, we use observational data to
quantify the slow, quiescent reconnection with preexisting field, and find that
for small active regions between 20% and 40% of the total emerged flux may have
reconnected at any given time.


title:
Possible Scale Invariant Linear Magnetoresistance in Pyrochlore Iridates
  Bi$_2$Ir$_2$O$_7$

abstract:
  We report the observation of a linear magnetoresistance in single crystals
and epitaxial thin films of the pyrochlore iridate Bi$_2$Ir$_2$O$_7$. The
linear magnetoresistance is positive and isotropic at low temperatures, without
any sign of saturation up to 35 Tesla. As temperature increases, the linear
field dependence gradually evolves to a quadratic field dependence. The
temperature and field dependence of magnetoresistance of Bi$_2$Ir$_2$O$_7$
bears strikingly resemblance to the scale invariant magnetoresistance observed
in the strange metal phase in high Tc cuprates. However, the residual
resistivity of Bi$_2$Ir$_2$O$_7$ is more than two orders of magnitude higher
than the curpates. Our results suggest that the correlation between linear
magnetoresistance and quantum fluctuations may exist beyond high temperature
superconductors.


title:
Quantum Interactions with Closed Timelike Curves and Superluminal
  Signaling

abstract:
  There is now a significant body of results on quantum interactions with
closed timelike curves (CTCs) in the quantum information literature, for both
the Deutsch model of CTC interactions (D-CTCs) and the projective model
(P-CTCs). As a consequence, there is a prima facie argument exploiting
entanglement that CTC interactions would enable superluminal and, indeed,
effectively instantaneous signaling. In cases of spacelike separation between
the sender of a signal and the receiver, whether a receiver measures the local
part of an entangled state or a disentangled state to access the signal can
depend on the reference frame. We propose a consistency condition that gives
priority to either an entangled perspective or a disentangled perspective in
spacelike separated scenarios. For D-CTC interactions, the consistency
condition gives priority to frames of reference in which the state is
disentangled, while for P-CTC interactions the condition selects the entangled
state. Using the consistency condition, we show that there is a procedure that
allows Alice to signal to Bob in the past via relayed superluminal
communications between spacelike separated Alice and Clio, and spacelike
separated Clio and Bob. This opens the door to time travel paradoxes in the
classical domain. Ralph (arXiv:1107.4675) first pointed this out for P-CTCs,
but we show that Ralph's procedure for a 'radio to the past' is flawed. Since
both D-CTCs and P-CTCs allow classical information to be sent around a
spacetime loop, it follows from a result by Aaronson and Watrous
(Proc.Roy.Soc.A, 465:631-647 (2009)) for CTC-enhanced classical computation
that a quantum computer with access to P-CTCs would have the power of PSPACE,
equivalent to a D-CTC-enhanced quantum computer.


title: Nuclear Forces from Lattice Quantum Chromodynamics

abstract:
  A century of coherent experimental and theoretical investigations have
uncovered the laws of nature that underly nuclear physics. The standard model
of strong and electroweak interactions, with its modest number of input
parameters, dictates the dynamics of the quarks and gluons - the underlying
building blocks of protons, neutrons, and nuclei. While the analytic techniques
of quantum field theory have played a key role in understanding the dynamics of
matter in high energy processes, they encounter difficulties when applied to
low-energy nuclear structure and reactions, and dense systems. Expected
increases in computational resources into the exa-scale during the next decade
will provide the ability to numerically compute a range of important strong
interaction processes directly from QCD with quantifiable uncertainties using
the technique of Lattice QCD. These calculations will refine the chiral nuclear
forces that are used as input into nuclear many-body calculations, including
the three- and four-nucleon interactions. I discuss the state-of-the-art
Lattice QCD calculations of quantities of interest in nuclear physics, progress
that is expected in the near future, and the impact upon nuclear physics.


title:
On Principal Spectrum Points/Principal Eigenvalues of Nonlocal Dispersal
  Operators and Applications

abstract:
  This paper is to investigate the dependence of the principal spectrum points
of nonlocal dispersal operators on underlying parameters and to consider its
applications. In particular, we study the effects of the spatial inhomogeneity,
the dispersal rate, and the dispersal distance on the existence of the
principal eigenvalues, the magnitude of the principal spectrum points, and the
asymptotic behavior of the principal spectrum points of nonlocal dispersal
operators with Dirichlet type, Neumann type, and periodic boundary conditions
in a unified way. We also discuss the applications of the principal spectral
theory of nonlocal dispersal operators to the asymptotic dynamics of two
species competition systems with nonlocal dispersal.


title: Theory and Simulation of Magnetic Materials: Physics at Phase Frontiers

abstract:
  The combination of theory and simulation is necessary in the investigation of
properties of complex systems where each method alone cannot do the task
properly. Theory needs simulation to test ideas and to check approximations.
Simulation needs theory for modeling and for understanding results coming out
from computers. In this review, we give recent examples to illustrate this
necessary combination in a few domains of interest such as frustrated spin
systems, surface magnetism, spin transport and melting. Frustrated spin systems
have been intensively studied for more than 30 years. Surface effects in
magnetic materials have been widely investigated also in the last three
decades. These fields are closely related to each other and their spectacular
development is due to numerous applications. We confine ourselves to
theoretical developments and numerical simulations on these subjects with
emphasis on spectacular effects occurring at frontiers of different phases.


title: Travelling waves for the cane toads equation with bounded traits

abstract:
  In this paper, we study propagation in a nonlocal reaction-diffusion-mutation
model describing the invasion of cane toads in Australia. The population of
toads is structured by a space variable and a phenotypical trait and the
space-diffusivity depends on the trait. We use a Schauder topological degree
argument for the construction of some travelling wave solutions of the model.
The speed $c^*$ of the wave is obtained after solving a suitable spectral
problem in the trait variable. An eigenvector arising from this eigenvalue
problem gives the flavor of the profile at the edge of the front. The major
difficulty is to obtain uniform $L^\infty$ bounds despite the combination of
non local terms and an heterogeneous diffusivity.


title:
Note on scalars, perfect fluids, constrained field theories, and all
  that

abstract:
  The relation of a scalar field with a perfect fluid has generated some debate
along the last few years. In this paper we argue that shift-invariant scalar
fields can describe accurately the potential flow of an isentropic perfect
fluid, but, in general, the identification is possible only for a finite period
of time. After that period in the evolution the dynamics of the scalar field
and the perfect fluid branch off. The Lagrangian density for the
velocity-potential can be read directly from the expression relating the
pressure with the Taub charge and the entropy per particle in the fluid,
whereas the other quantities of interest can be obtained from the thermodynamic
relations.


title:
Measurement in the de Broglie-Bohm interpretation: Double-slit,
  Stern-Gerlach and EPR-B

abstract:
  We propose a pedagogical presentation of measurement in the de Broglie-Bohm
interpretation. In this heterodox interpretation, the position of a quantum
particle exists and is piloted by the phase of the wave function. We show how
this position explains determinism and realism in the three most important
experiments of quantum measurement: double-slit, Stern-Gerlach and EPR-B.
First, we demonstrate the conditions in which the de Broglie-Bohm
interpretation can be assumed to be valid through continuity with classical
mechanics. Second, we present a numerical simulation of the double-slit
experiment performed by J\"onsson in 1961 with electrons. It demonstrates the
continuity between classical mechanics and quantum mechanics: evolution of the
probability density at various distances and convergence of the quantum
trajectories to the classical trajectories when h tends to 0. Third, we present
an analytic expression of the wave function in the Stern-Gerlach experiment.
This explicit solution requires the calculation of a Pauli spinor with a
spatial extension. This solution enables to demonstrate the decoherence of the
wave function and the three postulates of quantum measurement: quantization,
the Born interpretation and wave function reduction. The spinor spatial
extension also enables the introduction of the de Broglie-Bohm trajectories,
which gives a very simple explanation of the particles' impact and of the
measurement process. Finally, we study the EPR-B experiment, the Bohm version
of the Einstein-Podolsky-Rosen experiment. Its theoretical resolution in space
and time shows that a causal interpretation exists where each atom has a
position and a spin. This interpretation avoids the flaw of the previous causal
interpretation. We recall that a physical explanation of non-local influences
is possible.


title:
Resummed thermodynamic perturbation theory for bond cooperativity in
  associating fluids

abstract:
  We develop a resummed thermodynamic perturbation theory for bond
cooperativity in associating fluids by extension of Wertheim's multi - density
formalism. We specifically consider the case of an associating hard sphere with
two association sites and both pairwise and triplet contributions to the
energy. To test the theory we perform new monte carlo simulations. Theory and
simulation are found to be in excellent agreement.