title:
Wave-like warp propagation in circumbinary discs I. Analytic theory and
  numerical simulations

abstract:
  In this paper we analyse the propagation of warps in protostellar
circumbinary discs. We use these systems as a test environment in which to
study warp propagation in the bending-wave regime, with the addition of an
external torque due to the binary gravitational potential. In particular, we
want to test the linear regime, for which an analytic theory has been
developed. In order to do so, we first compute analytically the steady state
shape of an inviscid disc subject to the binary torques. The steady state tilt
is a monotonically increasing function of radius. In the absence of viscosity,
the disc does not present any twist. Then, we compare the time-dependent
evolution of the warped disc calculated via the known linearised equations both
with the analytic solutions and with full 3D numerical simulations, which have
been performed with the PHANTOM SPH code using 2 million particles. We find a
good agreement both in the tilt and in the phase evolution for small
inclinations, even at very low viscosities. Moreover, we have verified that the
linearised equations are able to reproduce the diffusive behaviour when
{\alpha} > H/R, where {\alpha} is the disc viscosity parameter. Finally, we
have used the 3D simulations to explore the non-linear regime. We observe a
strongly non-linear behaviour, which leads to the breaking of the disc. Then,
the inner disc starts precessing with its own precessional frequency. This
behaviour has already been observed with numerical simulations in accretion
discs around spinning black holes. The evolution of circumstellar accretion
discs strongly depends on the warp evolution. Therefore the issue explored in
this paper could be of fundamental importance in order to understand the
evolution of accretion discs in crowded environments, when the gravitational
interaction with other stars is highly likely, and in multiple systems.


title:
Force-Field Functor Theory: Classical Force-Fields which Reproduce
  Equilibrium Quantum Distributions

abstract:
  Feynman and Hibbs were the first to variationally determine an effective
potential whose associated classical canonical ensemble approximates the exact
quantum partition function. We examine the existence of a map between the local
potential and an effective classical potential which matches the exact quantum
equilibrium density and partition function. The usefulness of such a mapping
rests in its ability to readily improve Born-Oppenheimer potentials for use
with classical sampling. We show that such a map is unique and must exist. To
explore the feasibility of using this result to improve classical molecular
mechanics, we numerically produce a map from a library of randomly generated
one-dimensional potential/effective potential pairs then evaluate its
performance on independent test problems. We also apply the map to simulate
liquid para-hydrogen, finding that the resulting radial pair distribution
functions agree well with path integral Monte Carlo simulations. The surprising
accessibility and transferability of the technique suggest a quantitative route
to adapting Born-Oppenheimer potentials, with a motivation similar in spirit to
the powerful ideas and approximations of density functional theory.

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


title:
Wave-like warp propagation in circumbinary discs II. Application to KH
  15D

abstract:
  KH 15D is a protostellar binary system that shows a peculiar light curve. In
order to model it, a narrow circumbinary precessing disc has been invoked, but
a proper dynamical model has never been developed. In this paper, we
analytically address the issue of whether such a disc can rigidly precess
around KH 15D, and we relate the precessional period to the main parameters of
the system. Then, we simulate the disc's dynamics by using a 1D model developed
in a companion paper, such that the warp propagates into the disc as a bending
wave, which is expected to be the case for protostellar discs. The validity of
such an approach has been confirmed by comparing its results with full 3D SPH
simulations on extended discs. In the present case, we use this 1D code to
model the propagation of the warp in a narrow disc. If the inner truncation
radius of the disc is set by the binary tidal torques at {\sim} 1 AU, we find
that the disc should extend out to 6-10 AU (depending on the models), and is
therefore wider than previously suggested. Our simulations show that such a
disc does reach an almost steady state, and then precesses as a rigid body. The
disc displays a very small warp, with a tilt inclination that increases with
radius in order to keep the disc in equilibrium against the binary torque.
However, for such wider discs, the presence of viscosity leads to a secular
decay of the tilt on a timescale of {\approx} 3000 ({\alpha}/0.05)^(-1) years,
where {\alpha} is the disc viscosity parameter. The presence of a third body
(such as a planet), orbiting at roughly 10 AU might simultaneously explain the
outer truncation of the disc and the maintenance of the tilt for a prolonged
time.


title:
The quadruple pre-main sequence system LkCa3: Implications for stellar
  evolution models

abstract:
  We report the discovery that the pre-main sequence object LkCa3 in the
Taurus-Auriga star-forming region is a hierarchical quadruple system of M
stars. It was previously known to be a close (~0.5 arc sec) visual pair, with
one component being a moderately eccentric 12.94-day single-lined spectroscopic
binary. A re-analysis of archival optical spectra complemented with new
near-infrared spectroscopy shows both visual components to be double-lined, the
second one having a period of 4.06 days and a circular orbit. In addition to
the orbital elements, we determine optical and near-infrared flux ratios,
effective temperatures, and projected rotational velocities for all four stars.
Using existing photometric monitoring observations of the system that had
previously revealed the rotational period of the primary in the longer-period
binary, we detect also the rotational signal of the primary in the 4.06-day
binary, which is synchronized with the orbital motion. With only the assumption
of coevality, a comparison of all of these constraints with current stellar
evolution models from the Dartmouth series points to an age of 1.4 Myr and a
distance of 133 pc, consistent with previous estimates for the region and
suggesting the system is on the near side of the Taurus complex. Similar
comparisons of the properties of LkCa3 and of the well-known quadruple pre-main
sequence system GG Tau with the widely used models from the Lyon series for a
mixing length parameter of alpha_ML = 1.0 strongly favor the Dartmouth models.


title: Dynamics of Strongly Twisted Relativistic Magnetospheres

abstract:
  Magnetar magnetospheres are believed to be strongly twisted, due to shearing
of the stellar crust by internal magnetic stresses. We present time-dependent
axisymmetric simulations showing in detail the evolution of relativistic
force-free magnetospheres subjected to slow twisting through large angles. When
the twist amplitude is small, the magnetosphere moves quasi-statically through
a sequence of equilibria of increasing free energy. At some twist amplitude the
magnetosphere becomes tearing-mode unstable to forming a resistive current
sheet, initiating large-scale magnetic reconnection in which a significant
fraction of the magnetic free energy can be dissipated. This "critical" twist
angle is insensitive to the resistive length scale. Rapid shearing temporarily
stabilizes the magnetosphere beyond the critical angle, allowing the
magnetosphere of a rapidly differentially rotating star to store, and
dissipate, more free energy. In addition to these effects, shearing the surface
of a rotating star increases the spindown torque applied to the star. If
shearing is much slower than rotation, the resulting spikes in spindown rate
can occur on timescales anywhere from the long twisting timescale to the
stellar spin period or shorter, depending both on the stellar shear
distribution and the existing distribution of magnetospheric twists. A model in
which energy is stored in the magnetosphere, and released by a magnetospheric
instability, therefore predicts large changes in the measured spindown rate
before SGR giant flares.


title:
The VMC survey -IX. Pilot study of the proper motion of stellar
  populations in the LMC from 2MASS and VISTA data

abstract:
  We use multi-epoch near-infrared observations from the VISTA survey of the
Magellanic Cloud system (VMC) to measure the proper motion of stars of the LMC,
in one tile of 1.5 deg^2 centred at (alpha, delta) = (05:59:23.136,
-66:20:28.68) and including the South Ecliptic Pole, with respect to their
2MASS position over a time baseline of ~10 years and from VMC observations
only, spanning a time range of ~1 year. Stars of different ages are selected
from the (J-Ks) vs. Ks diagram and their average coordinate displacement is
computed from the difference between Ks band observations for stars as faint as
Ks=19 mag. Proper motions are derived by averaging up to seven 2MASS-VMC
combinations in the first case and from the slope of the best fit line among
the seven VMC epochs in the second case. Separate proper motion values are
obtained for variable stars in the field. The proper motion of ~40,000 LMC
stars in the tile, with respect to ~8000 background galaxies, obtained from VMC
data alone, is mu_alpha cos(delta) = +2.20+/-0.06 (stat) +/-0.29 (sys) and
mu_delta = +1.70+/-0.06 (stat) +/-0.30 (sys) mas/yr. This value agrees with
recent ground-based determinations in a nearby field but is larger than studies
with the HST; the cause of this discrepancy may be due to additional systematic
errors in the data. The LMC proper motion is also clearly distinct from the
proper motion derived for stars of the Milky Way. The relative proper motion
between the foreground stars and the LMC stars is ~5 mas/yr. Furthermore, we
measure a decrease of the proper motion with increasing logarithm of stellar
age for LMC stars. This study, based on just one VMC tile, shows the potential
of the 2MASS-VMC and VMC-VMC combinations for a comprehensive investigation of
the proper motion across the Magellanic system. (Abridged)


title:
The Build-Up of Nuclear Stellar Cusps in Extreme Starburst Galaxies and
  Major Mergers

abstract:
  Nuclear stellar cusps are defined as central excess light component in the
stellar light profiles of galaxies and are suggested to be stellar relics of
intense compact starbursts in the central ~100-500 pc region of gas-rich major
mergers. Here we probe the build-up of nuclear cusps during the actual
starburst phase for a complete sample of Luminous Infrared Galaxy systems (85
LIRGs, with 11.4<log[LIR/L_sun]<12.5) in the GOALS sample. Cusp properties are
derived via 2-dimensional fitting of the nuclear stellar light imaged in the
near-infrared by the Hubble Space Telescope and have been combined with mid-IR
diagnostics for AGN/starburst characterization. We find that nuclear stellar
cusps are resolved in 76% of LIRGs (merger and non-interacting galaxies). The
cusp strength and luminosity increases with far-IR luminosity (excluding AGN)
and merger stage, confirming theoretical models that starburst activity is
associated with the build-up of nuclear stellar cusps. Evidence for ultra
compact nuclear starbursts is found in ~13% of LIRGs, which have a strong
unresolved central NIR light component but no significant contribution of an
AGN. The nuclear near-IR surface density (measured within 1 kpc radius)
increases by a factor of ~5 towards late merger stages. A careful comparison to
local early-type galaxies with comparable masses reveals (a) that local
(U)LIRGs have a significantly larger cusp fraction and (b) that the majority of
the cusp LIRGs have host galaxy luminosities (H-band) similar to core
ellipticals which is roughly one order in magnitude larger than for cusp
ellipticals.


title: Wilson Lines and Entanglement Entropy in Higher Spin Gravity

abstract:
  Holographic entanglement entropy provides a direct connection between
classical geometry and quantum entanglement; however the usual prescription
does not apply to theories of higher spin gravity, where standard notions of
geometry are no longer gauge invariant. We present a proposal for the
holographic computation of entanglement entropy in field theories dual to
higher spin theories of gravity in AdS3. These theories have a Chern-Simons
description, and our proposal involves a Wilson line in an infinite-dimensional
representation of the bulk gauge group. In the case of spin-2 gravity such
Wilson lines are the natural coupling of a heavy point particle to gravity and
so are equivalent to the usual prescription of Ryu and Takayanagi. For higher
spin gravity they provide a natural generalization of these ideas. We work out
spin-3 gravity in detail, showing that our proposal recovers many expected
results and computes thermal entropies of black holes with higher spin charge,
finding agreement with previous expressions in the literature. We encounter
some peculiarities in the case of non-unitary RG flow backgrounds and outline
future generalizations.


title: Towards MQGP

abstract:
  For the Ouyang embedding we calculate the chemical potential mu_C due to a
U(1) gauge field on the w.v. of N_f D7-branes wrapped around a 4-cycle in a
resolved warped deformed conifold with (M)N (fractional)D3-branes of [1], and
show the possible thermodynamical stability up to linear order in the embedding
parameter. In the spirit of [2] we obtain the local type IIA mirror using SYZ
mirror symmetry near (theta_{1,2},psi)=(<theta_{1,2}>,{0,2pi,,4pi}) and then
oxidize the same to M theory. We take two limits of this
uplift:(i)g_s,g_sN_f,g_sM^2/N,g_s^2M N_f<<1,g_sM,g_sN>>1 similar to [1]
effected by M eps^{-3d/2}, N eps^{-19d},g_s epsn^d,d>0 and eps<=O(0.01);(ii)the
`MQGP limit' g_sM^2/N<<1, g_sN>>1 for finite g_s,M, effected by: g_s eps, M
eps^{-3d/2},N eps^{-39d},d>0, eps<~1). The second limit is more suited for the
study of QGP (See [3]) and can only be addressed in M theory. The uplift gives
a black M3-brane solution whose near-horizon geometry near
theta_{1,2}=0,pi-branches, preserves 1/8 SUSY. We obtain eta/s=1/4pi for the
uplift and the diffusion constant for types IIB/IIA backgrounds comes out to be
~1/T, for both limits. The D=11 SUGRA action up to O(R^4,|G_4|^2) is expected
to receive dominant contributions near <theta_{1,2}>=0,pi due to poles.
Introducing a small-angle cut-off c and using the <theta_{1,2}>=c,(pi-c)-local
uplift the specific heat from the IR-finite part of the action (c-independent)
turns out to be positive indicative of the thermodynamical stability of the
uplift. An ALD-gravity-type interpretation can be given to the counter-terms
for(i). Its verified that the black M3-brane entropy S r_h^3 from M-theoretic
thermodynamical methods and the horizon areas of types IIB/IIA/M3-brane
solutions.


title: Detecting Similarity of Rational Plane Curves

abstract:
  A novel and deterministic algorithm is presented to detect whether two given
rational plane curves are related by means of a similarity, which is a central
question in Pattern Recognition. As a by-product it finds all such
similarities, and the particular case of equal curves yields all symmetries. A
complete theoretical description of the method is provided, and the method has
been implemented and tested in the Sage system for curves of moderate degrees.


title:
Moir\'e minibands in graphene heterostructures with almost commensurate
  sqrt3 x sqrt3 hexagonal crystals

abstract:
  We present a phenomenological theory of the low energy moir\'e minibands of
Dirac electrons in graphene placed on an almost commensurate hexagonal underlay
with a unit cell pproximately three times larger than that of graphene.A slight
incommensurability results in a periodically modulated intervalley scattering
for electrons in graphene. In contrast to the perfectly commensurate Kekul\'e
distortion of graphene, such supperlattice perturbation leaves the zero energy
Dirac cones intact, but is able to open a band gap at the edge of the first
moir\'e subbband, asymmetrically in the conduction and valence bands.


title:
Roots multiplicity and square-free factorization of polynomials using
  companion matrices

abstract:
  Given an arbitrary monic polynomial $f$ over a field $F$ of characteristic 0,
we use companion matrices to construct a polynomial $M_f\in F[X]$ of minimum
degree such that for each root $\alpha$ of $f$ in the algebraic closure of $F$,
$M_f(\alpha)$ is equal to the multiplicity $m(\alpha)$ of $\alpha$ as a root of
$f$. As an application of $M_f$ we give a new method to compute in $F[X]$ each
component of the square-free factorization $f=P_1P_2^2\cdots P_m^m$, where
$P_k$ is the product of all $X-\alpha$ with $m(\alpha)=k$, for $k=1, \dots,
m=\max m(\alpha)$.


title:
Heat, molecular vibrations, and adiabatic driving in non-equilibrium
  transport through interacting quantum dots

abstract:
  In this article we review aspects of charge and heat transport in interacting
quantum dots and molecular junctions under stationary and time-dependent
non-equilibrium conditions due to finite electrical and thermal bias. In
particular, we discuss how a discrete level spectrum can be beneficial for
thermoelectric applications, and investigate the detrimental effects of
molecular vibrations on the efficiency of a molecular quantum dot as an energy
converter. In addition, we consider the effects of a slow time-dependent
modulation of applied voltages on the transport properties of a quantum dot and
show how this can be used as a spectroscopic tool complementary to standard
dc-measurements. Finally, we combine time-dependent driving with
thermoelectrics in a double-quantum dot system - a nanoscale analogue of a
cyclic heat engine - and discuss its operation and the main limitations to its
performance.


title: A construction of $\mathfrak v$-adic modular forms

abstract:
  The classical theory of $p$-adic (elliptic) modular forms arose in the 1970's
from the work of
  J.-P.\ Serre \cite{se1} who took $p$-adic limits of the $q$-expansions of
these forms. It was soon expanded by N.\ Katz \cite{ka1} with a more functorial
approach. Since then the theory has grown in a variety of directions. In the
late 1970's, the theory of modular forms associated to Drinfeld modules was
born in analogy with elliptic modular forms \cite{go1}, \cite{go2}. The
associated expansions at $\infty$ are quite complicated and no obvious limits
at finite primes ${\mathfrak v}$ were apparent. Recently, however, there has
been progress in the $\mathfrak v$-adic theory, \cite{vi1}. Also recently, A.\
Petrov \cite{pe1}, building on previous work of \cite{lo1}, showed that there
is an intermediate expansion at $\infty$ called the "$A$-expansion," and he
constructed families of cusp forms with such expansions. It is our purpose in
this note to show that Petrov's results also lead to interesting ${\mathfrak
v}$-adic cusp forms \`a la Serre. Moreover the existence of these forms allows
us to readily conclude a mysterious decomposition of the associated Hecke
action.


title: An Overview of the Research on Texture Based Plant Leaf Classification

abstract:
  Plant classification has a broad application prospective in agriculture and
medicine, and is especially significant to the biology diversity research. As
plants are vitally important for environmental protection, it is more important
to identify and classify them accurately. Plant leaf classification is a
technique where leaf is classified based on its different morphological
features. The goal of this paper is to provide an overview of different aspects
of texture based plant leaf classification and related things. At last we will
be concluding about the efficient method i.e. the method that gives better
performance compared to the other methods.


title: Schwinger-Dyson Renormalization Group

abstract:
  We use the Schwinger-Dyson equations as a starting point to derive
renormalization flow equations. We show that Katanin's scheme arises as a
simple truncation of these equations. We then give the full renormalization
group equations up to third order in the irreducible vertex. Furthermore, we
show that to the fifth order, there exists a functional of the self-energy and
the irreducible four-point vertex whose saddle point is the solution of
Schwinger-Dyson equations.


title: Entanglement Entropy and Higher Spin Holography in AdS$_3$

abstract:
  A holographic correspondence has been recently developed between higher spin
theories in three-dimensional anti-de Sitter space (AdS_3) and two-dimensional
Conformal Field Theories (CFTs) with extended symmetries. A class of such
dualities involves SL(N,R)\times SL(N,R) Chern-Simons gauge theories in the
(2+1)-dimensional bulk spacetime, and CFTs with W_N symmetry algebras on the
(1+1)-dimensional boundary. The topological character of the Chern-Simons
theory forces one to reconsider standard geometric notions such as black hole
horizons and entropy, as well as the usual holographic dictionary. Motivated by
this challenge, in this note we present a proposal to compute entanglement
entropy in the W_N CFTs via holographic methods. In particular, we introduce a
functional constructed from Wilson lines in the bulk Chern-Simons theory that
captures the entanglement entropy in the CFTs dual to standard AdS_3 gravity,
corresponding to SL(2,R)\times SL(2,R) gauge group, and admits an immediate
generalization to the higher spin case. We explicitly evaluate this functional
for several known solutions of the Chern-Simons theory, including charged black
holes dual to thermal CFT states carrying higher spin charge, and show that it
reproduces expected features of entanglement entropy, study whether it obeys
strong subadditivity, and moreover show that it reduces to the thermal entropy
in the appropriate limit.


title:
X-ray resonant photoexcitation: line widths and energies of K{\alpha}
  transitions in highly charged Fe ions

abstract:
  Photoabsorption by and fluorescence of the K{\alpha} transitions in highly
charged iron ions are essential mechanisms for X-ray radiation transfer in
astrophysical environments. We study photoabsorption due to the main K{\alpha}
transitions in highly charged iron ions from heliumlike to fluorinelike (Fe
24+...17+) using monochromatic X-rays around 6.6 keV at the PETRA III
synchrotron photon source. Natural linewidths were determined with hitherto
unattained accuracy. The observed transitions are of particular interest for
the understanding of photoexcited plasmas found in X-ray binaries and active
galactic nuclei.


title:
The center of mass energy of two colliding particles in the STU black
  holes

abstract:
  In this paper we consider collision of two particle near the STU black hole
and calculate center of mass energy. In the case of uncharged black hole we
find that the maximum energy obtained near the black hole horizon which
similarly happen for charged black hole. We verify that the black hole charge
may be decreased or increased the center of mass energy near the black hole
horizon.


title: Joint Unitary Triangularization for Gaussian Multi-User MIMO Networks

abstract:
  The problem of transmitting a common message to multiple users over the
Gaussian multiple-input multiple-output broadcast channel is considered, where
each user is equipped with an arbitrary number of antennas. A closed-loop
scenario is assumed, for which a practical capacity-approaching scheme is
developed. By applying judiciously chosen unitary operations at the transmit
and receive nodes, the channel matrices are triangularized so that the
resulting matrices have equal diagonals, up to a possible multiplicative scalar
factor. This, along with the utilization of successive interference
cancellation, reduces the coding and decoding tasks to those of coding and
decoding over the single-antenna additive white Gaussian noise channel. Over
the resulting effective channel, any off-the-shelf code may be used. For the
two-user case, it was recently shown that such joint unitary triangularization
is always possible. In this paper, it is shown that for more than two users, it
is necessary to carry out the unitary linear processing jointly over multiple
channel uses, i.e., space-time processing is employed. It is further shown that
exact triangularization, where all resulting diagonals are equal, is still not
always possible, and appropriate conditions for the existence of such are
established for certain cases. When exact triangularization is not possible, an
asymptotic construction is proposed, that achieves the desired property of
equal diagonals up to edge effects that can be made arbitrarily small, at the
price of processing a sufficiently large number of channel uses together.


title:
Transistor operation and mobility enhancement in top-gated LaAlO_3 /
  SrTiO_3 heterostructures

abstract:
  We report the operation of LaAlO_3 / SrTiO_3 depletion mode top-gated
junction field-effect transistors using a range of LaAlO_3 thicknesses as the
top gate insulator. Gated Hall bars show near ideal transistor characteristics
at room temperature with on-off ratios greater than 1000. Lower temperature
measurements demonstrate a systematic increase in the Hall mobility as the
sheet carrier density in the channel is depleted via the top gate, providing a
route to higher mobility, lower density electron gases in this system.


title: An improved Landauer Principle with finite-size corrections

abstract:
  Landauer's Principle relates entropy decrease and heat dissipation during
logically irreversible processes. Most theoretical justifications of Landauer's
Principle either use thermodynamic reasoning or rely on specific models based
on arguable assumptions. Here, we aim at a general and minimal setup to
formulate Landauer's Principle in precise terms. We provide a simple and
rigorous proof of an improved version of the Principle, which is formulated in
terms of an equality rather than an inequality. The proof is based on quantum
statistical mechanics concepts rather than on thermodynamic argumentation. From
this equality version, we obtain explicit improvements of Landauer's bound that
depend on the effective size of the thermal reservoir and reduce to Landauer's
bound only for infinite-sized reservoirs.

categories: quant-ph cond-mat.stat-mech math-ph math.MP


title: Hypergraph covering problems motivated by genome assembly questions

abstract:
  The Consecutive-Ones Property (C1P) is a classical concept in discrete
mathematics that has been used in several genomics applications, from physical
mapping of contemporary genomes to the assembly of ancient genomes. A common
issue in genome assembly concerns repeats, genomic sequences that appear in
several locations of a genome. Handling repeats leads to a variant of the C1P,
the C1P with multiplicity (mC1P), that can also be seen as the problem of
covering edges of hypergraphs by linear and circular walks. In the present
work, we describe variants of the mC1P that address specific issues of genome
assembly, and polynomial time or fixed-parameter algorithms to solve them.


title: On second-order, divergence-free tensors

abstract:
  This paper deals with the problem of describing the vector spaces of
divergence-free, natural tensors on a pseudo-Riemannian manifold that are
second-order; i.e., that are defined using only second derivatives of the
metric.
  The main result establishes isomorphisms between these spaces and certain
spaces of tensors (at a point) that are invariant under the action of an
orthogonal group. This result is valid for tensors with an arbitrary number of
indices and symmetries among them and, in certain cases, it allows to
explicitly compute basis, using the theory of invariants of the orthogonal
group.
  In the particular case of tensors with two indices, we prove the Lovelock
tensors are a basis for the vector space of second-order tensors that are
divergence-free, thus refining the original Lovelock's statement.


title: Blind Calibration in Compressed Sensing using Message Passing Algorithms

abstract:
  Compressed sensing (CS) is a concept that allows to acquire compressible
signals with a small number of measurements. As such it is very attractive for
hardware implementations. Therefore, correct calibration of the hardware is a
central is- sue. In this paper we study the so-called blind calibration, i.e.
when the training signals that are available to perform the calibration are
sparse but unknown. We extend the approximate message passing (AMP) algorithm
used in CS to the case of blind calibration. In the calibration-AMP, both the
gains on the sensors and the elements of the signals are treated as unknowns.
Our algorithm is also applica- ble to settings in which the sensors distort the
measurements in other ways than multiplication by a gain, unlike previously
suggested blind calibration algorithms based on convex relaxations. We study
numerically the phase diagram of the blind calibration problem, and show that
even in cases where convex relaxation is pos- sible, our algorithm requires a
smaller number of measurements and/or signals in order to perform well.


title:
Quark and Leptonic Mixing Patterns from the Breakdown of a Common
  Discrete Flavor Symmetry

abstract:
  Assuming the Majorana nature of neutrinos, we recently performed a scan of
leptonic mixing patterns derived from finite discrete groups of order less than
1536. Here we show that the 3 groups identified there as giving predictions
close to experiment, also contain another class of abelian subgroups that
predict an interesting leading order quark mixing pattern where only the
Cabibbo angle is generated at leading order. We further broaden our study by
assuming that neutrinos are Dirac particles and find 4 groups of order up to
200 that can predict acceptable quark and leptonic mixing angles. Since large
flavor groups allow for a multitude of leading order mixing patterns, we define
a measure that is suitable to compare the predictivity of a given flavor group
taking this fact into account. We give the result of this measure for a wide
range of discrete flavor groups and identify the group (Z_18 \times Z_6)
\rtimes S_3 as being most predictive in the sense of this measure. We further
discuss alternative measures and their implications.


title: Directional Recurrence for Infinite Measure Preserving Z^d Actions

abstract:
  We define directional recurrence for infinite measure preserving Z^d actions
both intrinsically and via the unit suspension flow and prove that the two
definitions are equivalent. We study the structure of the set of recurrent
directions and show it is always a G_delta set. We construct an example of a
recurrent action with no recurrent directions, answering a question posed in a
2007 paper of Daniel J. Rudolph. We also show by example that it is possible
for a recurrent action to not be recurrent in an irrational direction even if
all its sub-actions are recurrent.


title: A Yamabe-type problem on smooth metric measure spaces

abstract:
  We describe and partially solve a natural Yamabe-type problem on smooth
metric measure spaces which interpolates between the Yamabe problem and the
problem of finding minimizers for Perelman's $\nu$-entropy. This problem
reduces in all dimensions on Euclidean space to the characterization of the
minimizers of the family of Gagliardo--Nirenberg--Sobolev inequalities studied
by Del Pino and Dolbeault. We show that minimizers always exist on a compact
manifold provided the so-called weighted Yamabe constant is strictly less than
its value on Euclidean space. We also show that strict inequality holds for a
large class of smooth metric measure spaces, but we will also give an example
which shows that minimizers of the weighted Yamabe constant do not always
exist.


title:
Some Results on Open Edge and Open Mobile Guarding of Polygons and
  Triangulations

abstract:
  This paper focuses on a variation of the Art Gallery problem that considers
open edge guards and open mobile guards. A mobile guard can be placed on edges
and diagonals of a polygon, and the "open" prefix means that the endpoints of
such edge or diagonal are not taken into account for visibility purposes. This
paper studies the number of guards that are sufficient and sometimes necessary
to guard some classes of simple polygons for both open edge and open mobile
guards. This problem is also considered for planar triangulation graphs using
open edge guards.


title:
CSS J134052.0+151341 : A Cataclysmic Binary Star with a Stripped,
  Evolved Secondary

abstract:
  I report spectroscopy and time-series photometry of the cataclysmic binary
CSS J134052.0+151341. The optical light is dominated by the secondary star,
which I classify as K4 (+-2 subclasses), yet the orbital period derived from
the absorption radial velocities is only 2.45 hr, implying a Roche radius much
too small to contain a main-sequence K star. The spectrum shows enhanced sodium
absorption in several lines, suggesting that the surface material has been
processed at high temperatures. CSS J134052.0+151341 appears to be a rare
example of a cataclysmic binary in which the secondary star is the stripped
core of a formerly much more massive star, that began mass transfer after much
of the core's nuclear evolution had taken place.


title:
Dimming the Internet: Detecting Throttling as a Mechanism of Censorship
  in Iran

abstract:
  In the days immediately following the contested June 2009 Presidential
election, Iranians attempting to reach news content and social media platforms
were subject to unprecedented levels of the degradation, blocking and jamming
of communications channels. Rather than shut down networks, which would draw
attention and controversy, the government was rumored to have slowed connection
speeds to rates that would render the Internet nearly unusable, especially for
the consumption and distribution of multimedia content. Since, political
upheavals elsewhere have been associated with headlines such as "High usage
slows down Internet in Bahrain" and "Syrian Internet slows during Friday
protests once again," with further rumors linking poor connectivity with
political instability in Myanmar and Tibet. For governments threatened by
public expression, the throttling of Internet connectivity appears to be an
increasingly preferred and less detectable method of stifling the free flow of
information. In order to assess this perceived trend and begin to create
systems of accountability and transparency on such practices, we attempt to
outline an initial strategy for utilizing a ubiquitious set of network
measurements as a monitoring service, then apply such methodology to shed light
on the recent history of censorship in Iran.


title:
Interaction of galactic wind with halo gas and the origin of multiphase
  extraplanar material

abstract:
  We study the interaction of galactic wind with hot halo gas using
hydrodynamical simulations. We find that the outcome of this interaction
depends crucially on the wind injection density and velocity. Various phases of
the extraplanar media such as high velocity clouds (HVCs), outflowing clouds,
and OVI regions can originate in the interaction zones of wind with the halo
gas, depending on the injection velocity and density. In our simulations the
size of the HVCs is of the order of 100 pc. The total mass contained in the
clouds is 10^5 -- 10^7 M_sun and they have a normal distribution of velocities
in the galactic standard of rest frame, similar to HVCs. For high injection
density and velocity, a significant number of clouds move outwards and resemble
the case of cold neutral outflows. Furthermore a 10^5 -- 10^6 K phase is formed
in our simulations which has a column density ~ 10^{18} cm^{-2}, and resembles
the observed OVI regions. The injection velocity and density are linked with
the mass loading factor of the outflow, efficiency of energy injection due to
supernovae and the SFR. Comparison of the predicted morphology of extraplanar
gas with observations can serve as a useful diagnostic for constraining
feedback efficiency of outflows.


title:
Social Network Dynamics in a Massive Online Game: Network Turnover,
  Non-densification, and Team Engagement in Halo Reach

abstract:
  Online multiplayer games are a popular form of social interaction, used by
hundreds of millions of individuals. However, little is known about the social
networks within these online games, or how they evolve over time. Understanding
human social dynamics within massive online games can shed new light on social
interactions in general and inform the development of more engaging systems.
Here, we study a novel, large friendship network, inferred from nearly 18
billion social interactions over 44 weeks between 17 million individuals in the
popular online game Halo: Reach. This network is one of the largest, most
detailed temporal interaction networks studied to date, and provides a novel
perspective on the dynamics of online friendship networks, as opposed to mere
interaction graphs. Initially, this network exhibits strong structural turnover
and decays rapidly from a peak size. In the following period, however, both
network size and turnover stabilize, producing a dynamic structural
equilibrium. In contrast to other studies, we find that the Halo friendship
network is non-densifying: both the mean degree and the average pairwise
distance are stable, suggesting that densification cannot occur when
maintaining friendships is costly. Finally, players with greater long-term
engagement exhibit stronger local clustering, suggesting a group-level social
engagement process. These results demonstrate the utility of online games for
studying social networks, shed new light on empirical temporal graph patterns,
and clarify the claims of universality of network densification.


title:
Discussion of the adiabatic hypothesis in control schemes using
  exceptional points

abstract:
  We present calculations for the action of laser pulses on vibrational
transfer within the H2+ and Na2 molecules in the presence of dissipation due to
photodissociation of the molecule. The laser fields perform closed loops
surrounding exceptional points in the laser parameter plane of intensity and
wavelength. In principle the process should produce controlled vibrational
transfers due to an adiabatic flip of the dressed eigenstates. We directly
solve the Schr\"odinger equation with the complete time-dependent field instead
of using the adiabatic Floquet formalism which initially suggested the design
of the laser pulses. Results given by wavepacket propagations disagree with
predictions obtained using the adiabatic hypothesis. Thus we show that there
are large non-adiabatic exchanges and that the dissipative character of the
dynamics renders the adiabatic flip very difficult to obtain. Using much longer
durations than expected from previous studies, the adiabatic flip is only
obtained for the Na2 molecule and with strong dissociation.


title:
Results of the Swift Monitoring Campaign of the X-ray Binary 4U 1957+11:
  Constraints on Binary Parameters

abstract:
  We present new results of uniform spectral analysis of Swift/XRT observations
of the X-ray binary system 4U 1957+11. This includes 26 observations of the
source made between MJD 54282$-$55890 (2007 July 01 $-$ 2011 November 25). All
26 spectra are predominantly thermal, and can be modeled well with emission
from an accretion disk around a black hole. We analyze all 26 spectra jointly
using traditional chi-squared fitting as well as Markov Chain Monte Carlo
simulations. The results from both methods agree, and constrains on model
parameters like inclination, column density, and black hole spin. These results
indicate that the X-ray emitting inner accretion disk is inclined to our
line-of-sight by $77.6^{+1.5}_{-2.2}$ degrees. Additionally, the other
constraints we obtain on parameters like the column density and black hole spin
are consistent with previous X-ray observations. Distances less than 5 kpc are
unlikely and not only ruled out based on our analysis but also from other
independent observations. Based on model-derived bolometric luminosities, we
require the source distance to be >10 kpc if the black hole's mass is >10
M$_{Sun}$. If the hole's mass is <10 M$_{Sun}$, then the distance could be in
the range of 5$-$10 kpc.


title: Quantum Diffusion with Drift and the Einstein Relation I

abstract:
  We study the dynamics of a quantum particle hopping on a simple cubic lattice
and driven by a constant external force. It is coupled to an array of
identical, independent thermal reservoirs consisting of free, massless Bose
fields, one at each site of the lattice. When the particle visits a site x of
the lattice it can emit or absorb field quanta of the reservoir at x. Under the
assumption that the coupling between the particle and the reservoirs and the
driving force are sufficiently small, we establish the following results: The
ergodic average over time of the state of the particle approaches a
non-equilibrium steady state (NESS) describing a non-zero mean drift of the
particle. Its motion around the mean drift is diffusive, and the diffusion
constant and the drift velocity are related to one another by the Einstein
relation.


title: Quantum Diffusion with Drift and the Einstein Relation II

abstract:
  This paper is a companion to 'Quantum Diffusion with Drift and the Einstein
Relation I' (jointly submitted to arXiv). Its purpose is to describe and prove
a certain number of technical results used in 'Quantum Diffusion with Drift and
the Einstein Relation I', but not proven there. Both papers concern long-time
properties (diffusion, drift) of the motion of a driven quantum particle
coupled to an array of thermal reservoirs. The main technical results derived
in the present paper are $(1)$ an asymptotic perturbation theory applicable for
small driving, and, $(2)$ the construction of time-dependent correlation
functions of particle observables.


title: High-Precision Spectroscopy with Counter-Propagating Femtosecond Pulses

abstract:
  An experimental realization of high-precision direct frequency comb
spectroscopy using counter-propagating femtosecond pulses on two-photon atomic
transitions is presented. Doppler broadened background signal, hampering
precision spectroscopy with ultrashort pulses, is effectively eliminated with a
simple pulse shaping method. As a result, all four 5S-7S two-photon transitions
in a rubidium vapor are determined with both statistical and systematic
uncertainties below 10$^{-11}$, which is an order of magnitude better than
previous experiments on these transitions.


title:
The problem of artificial precision in theories of vagueness: a note on
  the role of maximal consistency

abstract:
  The problem of artificial precision is a major objection to any theory of
vagueness based on real numbers as degrees of truth. Suppose you are willing to
admit that, under sufficiently specified circumstances, a predication of "is
red" receives a unique, exact number from the real unit interval [0,1]. You
should then be committed to explain what is it that determines that value,
settling for instance that my coat is red to degree 0.322 rather than 0.321. In
this note I revisit the problem in the important case of {\L}ukasiewicz
infinite-valued propositional logic that brings to the foreground the role of
maximally consistent theories. I argue that the problem of artificial
precision, as commonly conceived of in the literature, actually conflates two
distinct problems of a very different nature.


title:
Attractive and Repulsive Casimir Vacuum Energy with General Boundary
  Conditions

abstract:
  The infrared behavior of quantum field theories confined in bounded domains
is strongly dependent on the shape and structure of space boundaries. The most
significant physical effect arises in the behaviour of the vacuum energy. The
Casimir energy can be attractive or repulsive depending on the nature of the
boundary. We calculate the vacuum energy for a massless scalar field confined
between two homogeneous parallel plates with the most general type of boundary
conditions depending on four parameters. The analysis provides a powerful
method to identify which boundary conditions generate attractive or repulsive
Casimir forces between the plates. In the interface between both regimes we
find a very interesting family of boundary conditions which do not induce any
type of Casimir force. We also show that the attractive regime holds far beyond
identical boundary conditions for the two plates required by the Kenneth-Klich
theorem and that the strongest attractive Casimir force appears for periodic
boundary conditions whereas the strongest repulsive Casimir force corresponds
to anti-periodic boundary conditions. Most of the analysed boundary conditions
are new and some of them can be physically implemented with metamaterials.

categories: hep-th cond-mat.other math-ph math.MP quant-ph


title: Many-body interaction in fast soliton collisions

abstract:
  We study $n$-pulse interaction in fast collisions of $N$ solitons of the
cubic nonlinear Schr\"odinger (NLS) equation in the presence of generic weak
nonlinear loss. We develop a reduced model that yields the contribution of
$n$-pulse interaction to the amplitude shift for collisions in the presence of
weak $(2m+1)$-order loss, for any $n$ and $m$. We first employ the reduced
model and numerical solution of the perturbed NLS equation to analyze soliton
collisions in the presence of septic loss $(m=3)$. Our calculations show that
three-pulse interaction gives the dominant contribution to the
collision-induced amplitude shift already in a full-overlap four-soliton
collision, and that the amplitude shift strongly depends on the initial soliton
positions. We then extend these results for a generic weak nonlinear loss of
the form $G(|\psi|^{2})\psi$, where $\psi$ is the physical field and $G$ is a
Taylor polynomial of degree $m_{c}$. Considering $m_{c}=3$, as an example, we
show that three-pulse interaction gives the dominant contribution to the
amplitude shift in a six-soliton collision, despite the presence of low-order
loss. Our study quantitatively demonstrates that $n$-pulse interaction with
high $n$ values plays a key role in fast collisions of NLS solitons in the
presence of generic nonlinear loss. Moreover, the scalings of $n$-pulse
interaction effects with $n$ and $m$ and the strong dependence on initial
soliton positions lead to complex collision dynamics, which is very different
from the one observed in fast NLS soliton collisions in the presence of cubic
loss.


title:
von K\'arm\'an energy decay and heating of protons and electrons in a
  kinetic turbulent plasma

abstract:
  Decay in time of undriven weakly collisional kinetic plasma turbulence in
systems large compared to the ion kinetic scales is investigated using fully
electromagnetic particle-in-cell simulations initiated with transverse flow and
magnetic disturbances, constant density, and a strong guide field. The observed
energy decay is consistent with the von K\'arm\'an hypothesis of similarity
decay, in a formulation adapted to magnetohydrodyamics (MHD). Kinetic
dissipation occurs at small scales, but the overall rate is apparently
controlled by large scale dynamics. At small turbulence amplitude the electrons
are preferentially heated. At larger amplitudes proton heating is the dominant
effect. In the solar wind and corona the protons are typically hotter,
suggesting that these natural systems are in large amplitude turbulence regime.


title: The Yamabe problem on Dirichlet spaces

abstract:
  We continue our previous work studying critical exponent semilinear elliptic
(and subelliptic) problems which generalize the classical Yamabe problem. In
[3] the focus was on metric-measure spaces with an `almost smooth' structure,
with stratified spaces furnishing the key examples. The criterion for
solvability there is phrased in terms of a strict inequality of the global
Yamabe invariant with a `local Yamabe invariant', which captures information
about the local singular structure. All of this is generalized here to the
setting of Dirichlet spaces which admit a Sobolev inequality and satisfy a few
other mild hypotheses. Applications include a new approach to the nonspherical
part of the CR Yamabe problem.


title:
Three-Dimensional Quantification of Cellular Traction Forces and
  Mechanosensing of Thin Substrata by Fourier Traction Force Microscopy

abstract:
  We introduce a novel three-dimensional (3D) traction force microscopy (TFM)
method motivated by the recent discovery that cells adhering on plane surfaces
exert both in-plane and out-of-plane traction stresses. We measure the 3D
deformation of the substratum on a thin layer near its surface, and input this
information into an exact analytical solution of the elastic equilibrium
equation. These operations are performed in the Fourier domain with high
computational efficiency, allowing to obtain the 3D traction stresses from raw
microscopy images virtually in real time. We also characterize the error of
previous two-dimensional (2D) TFM methods that neglect the out-of-plane
component of the traction stresses. This analysis reveals that, under certain
combinations of experimental parameters (\ie cell size, substratums' thickness
and Poisson's ratio), the accuracy of 2D TFM methods is minimally affected by
neglecting the out-of-plane component of the traction stresses. Finally, we
consider the cell's mechanosensing of substratum thickness by 3D traction
stresses, finding that, when cells adhere on thin substrata, their out-of-plane
traction stresses can reach four times deeper into the substratum than their
in-plane traction stresses. It is also found that the substratum stiffness
sensed by applying out-of-plane traction stresses may be up to 10 times larger
than the stiffness sensed by applying in-plane traction stresses.


title: Discrete perceptrons

abstract:
  Perceptrons have been known for a long time as a promising tool within the
neural networks theory. The analytical treatment for a special class of
perceptrons started in seminal work of Gardner \cite{Gar88}. Techniques
initially employed to characterize perceptrons relied on a statistical
mechanics approach. Many of such predictions obtained in \cite{Gar88} (and in a
follow-up \cite{GarDer88}) were later on established rigorously as mathematical
facts (see, e.g.
\cite{SchTir02,SchTir03,TalBook,StojnicGardGen13,StojnicGardSphNeg13,StojnicGardSphErr13}).
These typically related to spherical perceptrons. A lot of work has been done
related to various other types of perceptrons. Among the most challenging ones
are what we will refer to as the discrete perceptrons. An introductory
statistical mechanics treatment of such perceptrons was given in
\cite{GutSte90}. Relying on results of \cite{Gar88}, \cite{GutSte90}
characterized many of the features of several types of discrete perceptrons. We
in this paper, consider a similar subclass of discrete perceptrons and provide
a mathematically rigorous set of results related to their performance. As it
will turn out, many of the statistical mechanics predictions obtained for
discrete predictions will in fact appear as mathematically provable bounds.
This will in a way emulate a similar type of behavior we observed in
\cite{StojnicGardGen13,StojnicGardSphNeg13,StojnicGardSphErr13} when studying
spherical perceptrons.


title:
Full Spectral Survey of Active Galactic Nuclei in the Rossi X-ray Timing
  Explorer Archive

abstract:
  We have analyzed spectra for all active galactic nuclei in the Rossi X-ray
Timing Explorer (RXTE) archive. We present long-term average values of
absorption, Fe line equivalent width, Compton reflection and photon index, as
well as calculating fluxes and luminosities in the 2-10 keV band for 100 AGN
with sufficient brightness and overall observation time to yield high quality
spectral results. We compare these parameters across the different
classifications of Seyferts and blazars. Our distributions of photon indices
for Seyfert 1's and 2's are consistent with the idea that Seyferts share a
common central engine, however our distributions of Compton reflection hump
strengths do not support the classical picture of absorption by a torus and
reflection off a Compton-thick disk with type depending only on inclination
angle. We conclude that a more complex reflecting geometry such as a combined
disk and torus or clumpy torus is likely a more accurate picture of the
Compton-thick material. We find that Compton reflection is present in ~85% of
Seyferts and by comparing Fe line EW's to Compton reflection hump strengths we
have found that on average 40% of the Fe line arises in Compton thick material,
however this ratio was not consistent from object to object and did not seem to
be dependent on optical classification.


title:
Measurement of the elastoresistivity coefficients of the underdoped
  iron-arsenide Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$

abstract:
  A new method is presented for measuring terms in the elastoresistivity tensor
$m_{ij}$ of single crystal samples with tetragonal symmetry. The technique is
applied to a representative underdoped Fe-arsenide,
Ba(Fe$_{0.975}$Co$_{0.025}$)$_2$As$_2$, revealing an anomalously large and
anisotropic elastoresistance in comparison to simple metals. The $m_{66}$
coefficient follows a Curie-Weiss temperature dependence, providing direct
evidence that the tetragonal-to-orthorhombic structural phase transition that
occurs at $T_s$ = 97.5 K in this material is not the result of a true-proper
ferro-elastic transition. Rather, the material suffers a pseudo-proper
transition for which the lattice strain is not the primary order parameter.


title: Glassy magnetic behavior in the metamagnetic DyAlO3 doped with Cr

abstract:
  Magnetic properties of DyAl$_{0.926}$Cr$_{0.074}$O$_3$ and DyAlO$_3$ were
studied. We found that both compounds are antiferromagnetic with a low N\'eel
transition temperature. At higher temperatures the magnetic characteristics
show a Curie-Weiss dependence. The N\'eel temperature disappears when a field
of about 2 T is applied, the system changes from an antiferromagnetic to a weak
ferromagnetic behavior due to a metamagnetic transition. Furthermore, AC
magnetic measurements in the Cr doped compound, at different frequencies, show
a spin glass-like behavior. These transitions were studied and corroborated by
specific heat measurements. We found the presence of metamagnetism and spin
glass in the compound doped with chromium, determining that the small addition
of chromium atoms modifies the magnetic properties of the compound DyAlO$_3$,
resulting in new features such as the spin glass-like behavior.


title: Revisiting scaling relations for giant radio halos in galaxy clusters

abstract:
  Many galaxy clusters host Megaparsec-scale radio halos, generated by
ultrarelativistic electrons in the magnetized intracluster medium. Correlations
between the power of radio halos and the thermal properties of the hosting
clusters were established in the last decade, including the connection between
the presence of a halo and cluster mergers. The X-ray luminosity and redshift
limited Extended GMRT Radio Halo Survey provides a rich and unique dataset for
statistical studies of the halos. We uniformly analyze the radio and X-ray data
for the GMRT cluster sample, and use the new Planck SZ catalog, to revisit the
correlations between the power of halos and the thermal properties of galaxy
clusters. We find that the radio power of halos at 1.4 GHz scales with the
cluster X-ray (0.1--2.4 keV) luminosity computed within R_500 as P_1.4
L_500^2.0. Our bigger and more homogenous sample confirms that the X-ray
luminous (L_500 > 5x10^44 erg/s) clusters branch into two populations --- radio
halos lie on the correlation, while clusters with upper limits to radio-halo
emission are well below that correlation. This bimodality remains if we excise
cool cores from the X-ray luminosities. Correlating with Planck data, we find
that P_1.4 scales with the cluster integrated SZ signal within R_500 as P_1.4
Y_500^2.1, in line with previous findings. However, contrary to previous
studies that were limited by incompleteness and small sample size, we find that
the "SZ-luminous" Y_500 > 6x10^-5 Mpc^2 clusters show a bimodal behavior
similar to that in the radio-X-ray diagram. Bimodality of both correlations can
be traced to clusters dynamics, with radio halos found exclusively in merging
clusters. These results confirm the key role of mergers for the origin of giant
radio halos, suggesting that they trigger the relativistic particle
acceleration.


title: Interaction of Ultra Relativistic e- e+ Fireball Beam with Plasma

abstract:
  Ab initio simulations of the propagation in a plasma of a soon to be
available relativistic electron-positron beam or fireball beam provide an
effective mean for the study of microphysics relevant to astrophysical
scenarios. We show that the current filamentation instability associated with
some of these scenarios reaches saturation after only 10 cm of propagation in a
typical laboratory plasma with a density 10^17/cc. The different regimes of the
instability, from the purely transverse to the mixed mode filamentation, can be
accessed by varying the background plasma density. The instability generates
large local plasma gradients, intense transverse magnetic fields, and enhanced
emission of radiation. We suggest that these effects may be observed
experimentally for the first time.


title:
\beta-supergravity: a ten-dimensional theory with non-geometric fluxes,
  and its geometric framework

abstract:
  We present a ten-dimensional theory, named \beta-supergravity, that contains
non-geometric fluxes and could uplift some four-dimensional gauged
supergravities. Building on earlier work, we study here its NSNS sector, where
Q- and R-fluxes are precisely identified. Interestingly, the Q-flux is captured
in an analogue of the Levi-Civita spin connection, giving rise to a second
curvature scalar. We reproduce the ten-dimensional Lagrangian using the
Generalized Geometry formalism; this provides us with enlightening
interpretations of the new structures. Then, we derive the equations of motion
of our theory, and finally discuss further aspects: the dimensional reduction
to four dimensions and comparison to gauged supergravities, the obtention of
ten-dimensional purely NSNS solutions, the extensions to other sectors and new
objects, the supergravity limit, and eventually the symmetries, in particular
the \beta gauge transformation. We also introduce the related notion of a
generalized cotangent bundle.


title: On the Bergman Projection and the Lu Qi-Keng Conjecture

abstract:
  On a reasonable class of domains in $\CC^n$, we characterize those
holomorphic functions which continue analytically past the boundary. Then we
give some applications of this result to holomorphic mappings. In addition,
some new results about the Lu Qi-Keng conjecture are treated.


title: Scholte waves generated by seafloor topography

abstract:
  Seafloor topography can excite strong interface waves called Scholte waves
that are often dispersive and characterized by slow propagation but large
amplitude. This type of wave can be used to invert for near seafloor shear wave
velocity structure that is important information for multi-component P-S
seismic imaging. Three different approaches are taken to understand excitation
of Scholte waves and numerical aspects of modeling Scholte waves, including
analytical Cagniard-de Hoop analysis, the boundary integral method and a
staggered grid finite difference method. For simple media for which the Green's
function can be easily computed, the boundary element method produces accurate
results. The finite difference method shows strong numerical artifacts and
stagnant artificial waves can be seen in the vicinity of topography at the
fluid-solid interface even when using fine computational grids. However, the
amplitude of these artificial waves decays away from the seafloor. It is
sensible to place receivers away from the fluid-solid interface for seismic
modeling. To investigate Scholte wave generation, one needs to correctly
implement the fluid-solid boundary condition. It is also shown through
numerical examples including using a seafloor profile from the recent SEG
Advanced Modeling (SEAM) Project that even mild topographic features can
generate Scholte waves and these waves can be used to constrain near seafloor S
wave velocity by dispersion analysis of interface Scholte waves. The
implication to the full waveform inversion is that, although low frequency data
are crucial for convergence, seafloor topography may have a large effect on low
frequency seismic waves.


title: Approximation Algorithm for Sparsest k-Partitioning

abstract:
  Given a graph $G$, the sparsest-cut problem asks to find the set of vertices
$S$ which has the least expansion defined as $$\phi_G(S) :=
\frac{w(E(S,\bar{S}))}{\min \set{w(S), w(\bar{S})}}, $$ where $w$ is the total
edge weight of a subset. Here we study the natural generalization of this
problem: given an integer $k$, compute a $k$-partition $\set{P_1, \ldots, P_k}$
of the vertex set so as to minimize $$ \phi_k(\set{P_1, \ldots, P_k}) := \max_i
\phi_G(P_i). $$ Our main result is a polynomial time bi-criteria approximation
algorithm which outputs a $(1 - \e)k$-partition of the vertex set such that
each piece has expansion at most $O_{\varepsilon}(\sqrt{\log n \log k})$ times
$OPT$. We also study balanced versions of this problem.


title: Gradient bounds for Wachspress coordinates on polytopes

abstract:
  We derive upper and lower bounds on the gradients of Wachspress coordinates
defined over any simple convex d-dimensional polytope P. The bounds are in
terms of a single geometric quantity h_*, which denotes the minimum distance
between a vertex of P and any hyperplane containing a non-incident face. We
prove that the upper bound is sharp for d=2 and analyze the bounds in the
special cases of hypercubes and simplices. Additionally, we provide an
implementation of the Wachspress coordinates on convex polyhedra using Matlab
and employ them in a 3D finite element solution of the Poisson equation on a
non-trivial polyhedral mesh. As expected from the upper bound derivation, the
H^1-norm of the error in the method converges at a linear rate with respect to
the size of the mesh elements.


title: Mock theta functions and weakly holomorphic modular forms modulo 2 and 3

abstract:
  We prove that the coefficients of certain mock theta functions possess no
linear congruences modulo 3. We prove similar results for the moduli 2 and 3
for a wide class of weakly holomorphic modular forms and discuss applications.
This extends work of Radu on the behavior of the ordinary partition function
modulo 2 and 3.


title: On the Fattening of Lines in $\mathbf{P}^3$

abstract:
  We follow the lead of Bocci and Chiantini and show how differences in the
invariant alpha can be used to classify certain classes of subschemes of P^3.
Specifically, we will seek to classify arithmetically Cohen-Macaulay
codimension 2 subschemes of P^3 in the manner Bocci and Chiantini classified
points in P^2. The first section will seek to motivate our consideration of the
invariant alpha by relating it to the Hilbert function and gamma, following the
work of Bocci and Chiantini, and Dumnicki, et. al. The second section will
contain our results classifying arithmetically Cohen-Macaulay codimension 2
subschemes of P^3. This work is adapted from the author's Ph.D. dissertation.


title: Modular Data and Verlinde Formulae for Fractional Level WZW Models II

abstract:
  This article gives a complete account of the modular properties and Verlinde
formula for conformal field theories based on the affine Kac-Moody algebra
sl(2) at an arbitrary admissible level k. Starting from spectral flow and the
structure theory of relaxed highest weight modules, characters are computed and
modular transformations are derived for every irreducible admissible module.
The culmination is the application of a continuous version of the Verlinde
formula to deduce non-negative integer structure coefficients which are
identified with Grothendieck fusion coefficients. The Grothendieck fusion rules
are determined explicitly. These rules reproduce the well-known fusion rules of
Koh and Sorba, negative coefficients included, upon quotienting the
Grothendieck fusion ring by a certain ideal.


title: The images of multilinear polynomials evaluated on $3\times 3$ matrices

abstract:
  Let $p$ be a multilinear polynomial in several noncommuting variables, with
coefficients in a algebraically closed field $K$ of arbitrary characteristic.
In this paper we classify the possible images of $p$ evaluated on $3\times 3$
matrices. The image is one of the following: \begin{itemize} \item \{0\}, \item
the set of scalar matrices, \item a (Zariski) dense subset of $\sl_3(K)$, the
matrices of trace 0,
  \item a dense subset of $M_3(K)$, \item the set of $3-$scalar matrices (i.e.,
matrices having eigenvalues $(\beta, \beta \varepsilon, \beta \varepsilon^2)$
where $\varepsilon$ is a cube root of 1), or \item the set of scalars plus
$3-$scalar matrices.


title:
Absolute neighbourhood retracts and spaces of holomorphic maps from
  Stein manifolds to Oka manifolds

abstract:
  The basic result of Oka theory, due to Gromov, states that every continuous
map $f$ from a Stein manifold $S$ to an elliptic manifold $X$ can be deformed
to a holomorphic map. It is natural to ask whether this can be done for all $f$
at once, in a way that depends continuously on $f$ and leaves $f$ fixed if it
is holomorphic to begin with. In other words, is $\scrO(S,X)$ a deformation
retract of $\scrC(S,X)$? We prove that it is if $S$ has a strictly
plurisubharmonic Morse exhaustion with finitely many critical points; in
particular, if $S$ is affine algebraic. The only property of $X$ used in the
proof is the parametric Oka property with approximation with respect to finite
polyhedra, so our theorem holds under the weaker assumption that $X$ is an Oka
manifold. Our main tool, apart from Oka theory itself, is the theory of
absolute neighbourhood retracts. We also make use of the mixed model structure
on the category of topological spaces.


title:
On the Fundamental Limits of Recovering Tree Sparse Vectors from Noisy
  Linear Measurements

abstract:
  Recent breakthrough results in compressive sensing (CS) have established that
many high dimensional signals can be accurately recovered from a relatively
small number of non-adaptive linear observations, provided that the signals
possess a sparse representation in some basis. Subsequent efforts have shown
that the performance of CS can be improved by exploiting additional structure
in the locations of the nonzero signal coefficients during inference, or by
utilizing some form of data-dependent adaptive measurement focusing during the
sensing process. To our knowledge, our own previous work was the first to
establish the potential benefits that can be achieved when fusing the notions
of adaptive sensing and structured sparsity -- that work examined the task of
support recovery from noisy linear measurements, and established that an
adaptive sensing strategy specifically tailored to signals that are tree-sparse
can significantly outperform adaptive and non-adaptive sensing strategies that
are agnostic to the underlying structure. In this work we establish fundamental
performance limits for the task of support recovery of tree-sparse signals from
noisy measurements, in settings where measurements may be obtained either
non-adaptively (using a randomized Gaussian measurement strategy motivated by
initial CS investigations) or by any adaptive sensing strategy. Our main
results here imply that the adaptive tree sensing procedure analyzed in our
previous work is nearly optimal, in the sense that no other sensing and
estimation strategy can perform fundamentally better for identifying the
support of tree-sparse signals.


title: Nonsingular Promises from Born-Infeld Gravity

abstract:
  Born-Infeld determinantal gravity formulated in Weitzenbock spacetime is
discussed in the context of Friedmann-Robertson-Walker (FRW) cosmologies. It is
shown how the standard model big bang singularity is absent in certain
spatially flat FRW spacetimes, where the high energy regime is characterized by
a de Sitter inflationary stage of geometrical character, i.e., without the
presence of the inflaton field. This taming of the initial singularity is also
achieved for some spatially curved FRW manifolds where the singularity is
replaced by a de Sitter stage or a big bounce of the scale factor depending on
certain combinations of free parameters appearing in the action. Unlike other
Born-Infeld-like theories in vogue, the one here presented is also capable of
deforming vacuum general relativistic solutions.


title: Masses and Distance of the Young Binary NTTS 045251+3016

abstract:
  As part of our continuing campaign to measure the masses of pre-main sequence
stars dynamically and thus to assess the reliability of the discrepant
theoretical calculations of contraction to the main sequence, we present new
results for NTTS 045251+3016, a visual and double-lined spectroscopic binary in
the Taurus Star Forming Region. We obtained new high angular resolution
astrometry and high spectral resolution spectroscopy at Keck Observatory. The
new data lead to a significant revision of previously published orbital
parameters. In particular, we find that the masses of the primary and secondary
are 0.86+/-0.11 and 0.55+/-0.05 M_sun, respectively, smaller than previously
reported, and that the system lies 158.7+/-3.9 pc from the sun, further than
previously reported.


title:
Electronic comparison of InAs wurtzite and zincblende phases using
  nanowire transistors

abstract:
  We compare the electronic characteristics of nanowire field-effect
transistors made using single pure wurtzite and pure zincblende InAs nanowires
with nominally identical diameter. We compare the transfer characteristics and
field-effect mobility versus temperature for these devices to better understand
how differences in InAs phase govern the electronic properties of nanowire
transistors.


title:
Absolutely continuous spectrum for quasi-periodic Schr\"odinger
  operators

abstract:
  I prove that quasi-periodic Schr\"odinger operators in arbitrary dimension
have some absolutely continuous spectrum.


title: High-Effciency Cross-Phase Modulation in a Gas-Filled Waveguide

abstract:
  Strong cross-Kerr non-linearities have been long sought after for quantum
information applications. Recent work has shown that they are intrinsically
unreliable in travelling wave configurations: cavity configurations avoid this,
but require knowledge of both the non-linearity and the loss. Here we present a
detailed systematic study of cross-phase modulation, and absorption, in a
rubidium vapour confined within a hollow-core photonic crystal fibre. Using a
two-photon transition, we observe phase modulations of up to $\pi$rad with a
signal power of 25$\mu$W, corresponding to a non-linear Kerr coefficient,
$n_2$, of $0.8 \times 10^{-6}$ cm$^2$/W, or $1.3 \times 10^{-6}$ rad per
photon.


title:
Group variable selection via convex Log-Exp-Sum penalty with application
  to a breast cancer survivor study

abstract:
  In many scientific and engineering applications, covariates are naturally
grouped. When the group structures are available among covariates, people are
usually interested in identifying both important groups and important variables
within the selected groups. Among existing successful group variable selection
methods, some methods fail to conduct the within group selection. Some methods
are able to conduct both group and within group selection, but the
corresponding objective functions are non-convex. Such a non-convexity may
require extra numerical effort. In this paper, we propose a novel
Log-Exp-Sum(LES) penalty for group variable selection. The LES penalty is
strictly convex. It can identify important groups as well as select important
variables within the group. We develop an efficient group-level coordinate
descent algorithm to fit the model. We also derive non-asymptotic error bounds
and asymptotic group selection consistency for our method in the
high-dimensional setting where the number of covariates can be much larger than
the sample size. Numerical results demonstrate the good performance of our
method in both variable selection and prediction. We applied the proposed
method to an American Cancer Society breast cancer survivor dataset. The
findings are clinically meaningful and lead immediately to testable clinical
hypotheses.


title: Interstellar scintillation is an indicator of astrometric stability

abstract:
  We examine the relationship between astrometric stability and astrophysical
properties in flat-spectrum radio-loud quasars making up the celestial
reference frame. We use position determinations from geodetic VLBI
measurements, and develop a new metric for source position stability. We then
compare this quantity to two measures of source compactness: structure index,
which probes structure on milliarcsecond scales; and the presence of
interstellar scintillation associated with the quasar, which probes scales of
tens of microarcseconds.
  We find that persistent scintillators have greater position stability than
episodic scintillators, which are in turn more stable than non-scintillators.
Scintillators are also more likely to be compact on milliarcsecond scales, as
measured by the structure index. Persistent scintillators are therefore
excellent candidates for inclusion in any future realisation of the celestial
reference frame. A list of these sources is presented in the Appendix.
  We find that slow (characteristic timescale >3 days) scintillators have more
stable positions than rapid scintillators, suggesting they are more compact.
High-cadence, long term monitoring is therefore required to identify other
members of this population of compact, high brightness temperature quasars.


title:
Energy Partition between Energetic Electrons and Turbulent Magnetic
  Field in Supernova Remnant RX J1713.7-3946

abstract:
  Current observations of supernova remnant (SNR) RX J1713.7-3946 favor the
leptonic scenario for the TeV emission, where the radio to X-ray emission is
produced via the synchrotron process and the $\gamma$-ray emission is produced
via the inverse Comptonization of soft background photons, and the electron
distribution can be inferred from the observed $\gamma$-ray spectrum with a
spectral inversion method. It is shown that the observed correlation between
the X-ray and $\gamma$-ray brightness of SNR RX J1713.7-3946 can be readily
explained with the assumption that the energy density of energetic electrons is
proportional to that of the magnetic field in such a scenario. A 2D
magnetohydrodynamic simulation is then carried out to model the overall
emission spectrum. It is found that the total energy of electrons above $\sim
1$ GeV is equal to that of the magnetic field. This is the first piece of
observational evidence for energy equipartition between energetic electrons and
magnetic field in the downstream of strong collision-less astrophysical shocks
of SNRs.


title:
No-go theorem for static scalar field dark matter halos with no Noether
  charges

abstract:
  Classical scalar fields have been considered as a possible effective
description of dark matter. We show that, for any metric theory of gravity, no
static, spherically symmetric, regular, spatially localized, attractive, stable
spacetime configuration can be sourced by the coherent excitation of a scalar
field with positive definite energy density and no Noether charges. In the
weak-field regime the result also applies for configurations with a repulsive
gravitational potential. This extends Derrick's theorem to the case of a
general (non-canonical) scalar field, including the self-gravitational effects.
Some possible ways out are briefly discussed.


title: Voter models with contrarian agents

abstract:
  In the voter and many other opinion formation models, agents are assumed to
behave as congregators (also called the conformists); they are attracted to the
opinions of others. In this study, I investigate linear extensions of the voter
model with contrarian agents. An agent is either congregator or contrarian and
assumes a binary opinion. I investigate three models that differ in the
behavior of the contrarian toward other agents. In model 1, contrarians mimic
the opinions of other contrarians and oppose (i.e., try to select the opinion
opposite to) those of congregators. In model 2, contrarians mimic the opinions
of congregators and oppose those of other contrarians. In model 3, contrarians
oppose anybody. In all models, congregators are assumed to like anybody. I show
that even a small number of contrarians prohibits the consensus in the entire
population to be reached in all three models. I also obtain the equilibrium
distributions using the van Kampen small-fluctuation approximation and the
Fokker-Planck equation for the case of many contrarians and a single
contrarian, respectively. I show that the fluctuation around the symmetric
coexistence equilibrium is much larger in model 2 than in models 1 and 3 when
contrarians are rare.


title: Force-Induced Unzipping Transitions in an Athermal Crowded Environment

abstract:
  Using theoretical arguments and extensive Monte Carlo (MC) simulations of a
coarse-grained three-dimensional off-lattice model of a \beta-hairpin, we
demonstrate that the equilibrium critical force, $F_c$, needed to unfold the
biopolymer increases non-linearly with increasing volume fraction occupied by
the spherical macromolecular crowding agent. Both scaling arguments and MC
simulations show that the critical force increases as $F_c \approx
\varphi_c^{\alpha}$. The exponent $\alpha$ is linked to the Flory exponent
relating the size of the unfolded state of the biopolymer and the number of
amino acids. The predicted power law dependence is confirmed in simulations of
the dependence of the isothermal extensibility and the fraction of native
contacts on $\varphi_c$. We also show using MC simulations that $F_c$ is
linearly dependent on the average osmotic pressure ($\mathrm{P}$) exerted by
the crowding agents on the \beta-hairpin. The highly significant linear
correlation coefficient of 0.99657 between $F_c$ and $\mathrm{P}$ makes it
straightforward to predict the dependence of the critical force on the density
of crowders. Our predictions are amenable to experimental verification using
Laser Optical Tweezers.


title: The finite and large-$N$ behaviors of independent-value matrix models

abstract:
  We investigate the finite and large $N$ behaviors of independent-value
O(N)-invariant matrix models. These are models defined with matrix-type fields
and with no gradient term in their action. They are generically
nonrenormalizable but can be handled by nonperturbative techniques. We find
that the functional of any O(N) matrix trace invariant may be expressed in
terms of an O(N)-invariant measure. Based on this result, we prove that, in the
limit that all interaction coupling constants go to zero, any interacting
theory is continuously connected to a pseudo-free theory. This theory differs
radically from the familiar free theory consisting in putting the coupling
constants to zero in the initial action. The proof is given for generic
finite-size matrix models, whereas, in the limiting case $N\rightarrow\infty$,
we succeed in showing this behavior for restricted types of actions using a
particular scaling of the parameters.


title: Friedel crystals and the outer crust of magnetars

abstract:
  The strong magnetic fields found on the surface of magnetars are known to
have profound effects in the physics of atoms in magnetar envelopes. We argue
that the Friedel oscillations in the Coulomb force between the ions due to
electron shielding can, for certain values of the parameters, be the dominant
effect determining the crystal structure in the outer crust of magnetars. We
estimate the densities and magnetic fields for which this occurs, compute some
of the elastic moduli and lattice phonon dispersion relations in this "Friedel
crystal" phase.


title: Generating Non-perturbative Physics from Perturbation Theory

abstract:
  In a large variety of quantum mechanical systems, we show that the full
non-perturbative expression for energy eigenvalues, containing all orders of
perturbative, non-perturbative and quasi-zero-mode terms, may be generated
directly from the perturbative expansion about the perturbative vacuum,
combined with a single global boundary condition. This provides a dramatic
realization of the principle of "resurgence", that the fluctuations about
different semiclassical saddle points are related to one another in a precise
quantitative manner. The analysis of quantum mechanics also generalizes to
certain calculable regimes of quantum field theory.


title:
On the formation time scale of massive cluster ellipticals based on deep
  near-IR spectroscopy at z~2

abstract:
  We present improved constraints on the formation time scale of massive
cluster galaxies based on rest-frame optical spectra of galaxies in a forming
cluster located at z=2.16. The spectra are obtained with MOIRCS on the Subaru
telescope with an integration time of ~7 hours. We achieve accurate redshift
measurements by fitting SEDs using the spectra and broad-band photometry
simultaneously, allowing us to identify probable cluster members. Clusters at
low redshifts are dominated by quiescent galaxies, but we find that quiescent
galaxies and star forming galaxies co-exist in this z=2 system. Interestingly,
the quiescent galaxies form a weak red sequence in the process of forming. By
stacking the spectra of star forming galaxies, we observe strong emission lines
such as [OII] and [OIII] and we obtain a tentative hint of AGN activities in
these galaxies. On the other hand, the stacked spectrum of the quiescent
galaxies reveals a clear 4000A break with a possible CaII H+K absorption
feature and strong emission lines such as [OII] are absent in the spectrum,
confirming the quiescent nature of these galaxies. We then perform detailed
spectral analyses of the stacked spectrum, which suggest that these massive
quiescent galaxies formed at redshifts between 3 and 4 on a time scale of <~0.5
Gyr. This short formation time scale is not reproduced in recent numerical
simulations. We discuss possible mechanisms for how these galaxies form 10^11
Msun stellar mass on a short time scale and become red and quiescent by z=2.


title: Non-Doppler Redshift and Dark Matter in the Coma Cluster

abstract:
  In 1929 Zwicky proposed a tired light theory to interpret the Hubble law
(Hubble 1929). The key of the tired light theory is to interpret the observed
redshift of galaxy as the non-Doppler effect. But the derivation of the dark
matter in the Coma cluster proposed by Zwicky in 1933 was based on the
interpretation that redshifts of galaxies were the Doppler effect, and the
non-Doppler effect was not considered at all. However, if there is a reasonable
non-Doppler effect and the great majority of the observed redshifts of galaxies
in the Coma cluster can be interpreted by the non-Doppler effect, then it's not
needed to introduce the dark matter in the Coma cluster to keep the stability
of the cluster. In this paper it is shown that the great majority of the
redshifts of galaxies in the Coma cluster are caused by the non-Doppler
redshift proposed by Zheng (2013), and a numerical estimation of the redshifts
of galaxies in the Coma cluster is presented.


title: Marginal empirical likelihood and sure independence feature screening

abstract:
  We study a marginal empirical likelihood approach in scenarios when the
number of variables grows exponentially with the sample size. The marginal
empirical likelihood ratios as functions of the parameters of interest are
systematically examined, and we find that the marginal empirical likelihood
ratio evaluated at zero can be used to differentiate whether an explanatory
variable is contributing to a response variable or not. Based on this finding,
we propose a unified feature screening procedure for linear models and the
generalized linear models. Different from most existing feature screening
approaches that rely on the magnitudes of some marginal estimators to identify
true signals, the proposed screening approach is capable of further
incorporating the level of uncertainties of such estimators. Such a merit
inherits the self-studentization property of the empirical likelihood approach,
and extends the insights of existing feature screening methods. Moreover, we
show that our screening approach is less restrictive to distributional
assumptions, and can be conveniently adapted to be applied in a broad range of
scenarios such as models specified using general moment conditions. Our
theoretical results and extensive numerical examples by simulations and data
analysis demonstrate the merits of the marginal empirical likelihood approach.


title:
Energy-Aware Scheme used in Multi-level Heterogeneous Wireless Sensor
  Networks

abstract:
  The wireless sensor networks (WSNs) is a power constrained system, since
nodes run on limited power batteries which shorten its lifespan.The main
challenge facing us in the design and conception of Wireless Sensor Networks
(WSNs) is to find the best way to extend their life span. The clustering
algorithm is a key technique used to increase the scalability and life span of
the network in general. In this paper, we propose and evaluate a distributed
energy-efficient clustering algorithm for WSNs. This heterogeneous-energy
protocol is a new clustering algorithm to decrease probability of failure nodes
and in which we introduce the node's remaining energy so as to determine the
cluster heads. We study the impact of heterogeneity of nodes on WSNs that are
hierarchically clustered. Finally, simulation results show that the proposed
algorithm increases the life span of the whole network and performs better than
LEACH and EEHC according to the metric:first node dies.


title:
Joint estimation of sparse multivariate regression and conditional
  graphical models

abstract:
  Multivariate regression model is a natural generalization of the classical
univari- ate regression model for fitting multiple responses. In this paper, we
propose a high- dimensional multivariate conditional regression model for
constructing sparse estimates of the multivariate regression coefficient matrix
that accounts for the dependency struc- ture among the multiple responses. The
proposed method decomposes the multivariate regression problem into a series of
penalized conditional log-likelihood of each response conditioned on the
covariates and other responses. It allows simultaneous estimation of the sparse
regression coefficient matrix and the sparse inverse covariance matrix. The
asymptotic selection consistency and normality are established for the
diverging dimension of the covariates and number of responses. The
effectiveness of the pro- posed method is also demonstrated in a variety of
simulated examples as well as an application to the Glioblastoma multiforme
cancer data.


title:
Event-Object Reasoning with Curated Knowledge Bases: Deriving Missing
  Information

abstract:
  The broader goal of our research is to formulate answers to why and how
questions with respect to knowledge bases, such as AURA. One issue we face when
reasoning with many available knowledge bases is that at times needed
information is missing. Examples of this include partially missing information
about next sub-event, first sub-event, last sub-event, result of an event,
input to an event, destination of an event, and raw material involved in an
event. In many cases one can recover part of the missing knowledge through
reasoning. In this paper we give a formal definition about how such missing
information can be recovered and then give an ASP implementation of it. We then
discuss the implication of this with respect to answering why and how
questions.


abstract:
  We study Hardy spaces for Fourier--Bessel expansions associated with Bessel
operators on $((0,1), x^{2\nu+1}\, dx)$ and $((0,1), dx)$. We define Hardy
spaces $H^1$ as the sets of $L^1$-functions for which their maximal functions
for the corresponding Poisson semigroups belong to $L^1$. Atomic
characterizations are obtained.


title: Experimental unconditionally secure bit commitment

abstract:
  Bit commitment is a fundamental cryptographic task that guarantees a secure
commitment between two mutually mistrustful parties and is a building block for
many cryptographic primitives, including coin tossing, zero-knowledge proofs,
oblivious transfer and secure two-party computation. Unconditionally secure bit
commitment was thought to be impossible until recent theoretical protocols that
combine quantum mechanics and relativity were shown to elude previous
impossibility proofs. Here we implement such a bit commitment protocol. In the
experiment, the committer performs quantum measurements using two quantum key
distribution systems and the results are transmitted via free-space optical
communication to two agents separated with more than 20 km. The security of the
protocol relies on the properties of quantum information and relativity theory.
We show that, in each run of the experiment, a bit is successfully committed
with less than 5.68*10^-2 cheating probability. Our result demonstrates
unconditionally secure bit commitment and the experimental feasibility of
relativistic quantum communication.


title:
Symbol and Bit Mapping Optimization for Physical-Layer Network Coding
  with Pulse Amplitude Modulation

abstract:
  In this paper, we consider a two-way relay network in which two users
exchange messages through a single relay using a physical-layer network coding
(PNC) based protocol. The protocol comprises two phases of communication. In
the multiple access (MA) phase, two users transmit their modulated signals
concurrently to the relay, and in the broadcast (BC) phase, the relay
broadcasts a network-coded (denoised) signal to both users. Nonbinary and
binary network codes are considered for uniform and nonuniform pulse amplitude
modulation (PAM) adopted in the MA phase, respectively. We examine the effect
of different choices of symbol mapping (i.e., mapping from the denoised signal
to the modulation symbols at the relay) and bit mapping (i.e., mapping from the
modulation symbols to the source bits at the user) on the system error-rate
performance. A general optimization framework is proposed to determine the
optimal symbol/bit mappings with joint consideration of noisy transmissions in
both communication phases. Complexity-reduction techniques are developed for
solving the optimization problems. It is shown that the optimal symbol/bit
mappings depend on the signal-to-noise ratio (SNR) of the channel and the
modulation scheme. A general strategy for choosing good symbol/bit mappings is
also presented based on a high-SNR analysis, which suggests using a symbol
mapping that aligns the error patterns in both communication phases and Gray
and binary bit mappings for uniform and nonuniform PAM, respectively.


title:
Cosmological Tests Using GRBs, the Star Formation Rate and Possible
  Abundance Evolution

abstract:
  The principal goal of this paper is to use attempts at reconciling the Swift
long gamma-ray bursts (LGRBs) with the star formation history (SFH) to compare
the predictions of $\Lambda$CDM with those in the $R_{\rm h}=ct$ Universe. In
the context of the former, we confirm that the latest Swift sample of GRBs
reveals an increasing evolution in the GRB rate relative to the star formation
rate (SFR) at high redshifts. The observed discrepancy between the GRB rate and
the SFR may be eliminated by assuming a modest evolution parameterized as
$(1+z)^{0.8}$---perhaps indicating a cosmic evolution in metallicity. However,
we find a higher metallicity cut of $Z=0.52Z_{\odot}$ than was seen in previous
studies, which suggested that LGRBs occur preferentially in metal poor
environments, i.e., $Z\sim0.1-0.3Z_{\odot}$. We use a simple power-law
approximation to the high-\emph{z} ($\ga 3.8$) SFH, i.e., $R_{\rm
SF}\propto[(1+z)/4.8]^{\alpha}$, to examine how the high-\emph{z} SFR may be
impacted by a possible abundance evolution in the Swift GRB sample. For an
expansion history consistent with $\Lambda$CDM, we find that the Swift redshift
and luminosity distributions can be reproduced with reasonable accuracy if
$\alpha=-2.41_{-2.09}^{+1.87}$. For the $R_{\rm h}=ct$ Universe, the GRB rate
is slightly different from that in $\Lambda$CDM, but also requires an extra
evolutionary effect, with a metallicity cut of $Z=0.44Z_{\odot}$. Assuming that
the SFR and GRB rate are related via an evolving metallicity, we find that the
GRB data constrain the slope of the high-\emph{z} SFR in $R_{\rm h}=ct$ to be
$\alpha=-3.60_{-2.45}^{+2.45}$. Both cosmologies fit the GRB/SFR data rather
well.


title:
Conditions for the solvability of the Cauchy problem for linear
  first-order functional differential equations

abstract:
  Conditions for the unique solvability of the Cauchy problem for a family of
scalar functional differential equations are obtained. These conditions are
sufficient for the solvability of the Cauchy problem for every equation from
the family and are necessary for the solvability of the Cauchy problem for all
equations from the family. In contrast to many known articles, we consider
equations with functional operators acting into the space of essentially
bounded functions.


title:
Rotor Bearing System Analysis Using the Transfer Matrix Method with
  Thickness Assumption of Disk and Bearing

abstract:
  One of the methods to find the natural frequencies of rotating systems is the
application of the transfer matrix method. In this method the rotor is modeled
as several elements along the shaft which have their own mass and moment of
inertia. Using these elements, the entire continuous system is discretized and
the corresponding differential equation can be stated in matrix form. The
bearings at the end of the shaft are modeled as equivalent spring and dampers
which are applied as boundary conditions to the discretized system. In this
paper the dynamics of a rotor-bearing system is analyzed, considering the
gyroscopic effect. The thickness of the disk and bearings is also taken into
account. Continuous model is used for shaft. Results Show that, the stiffness
of the shaft and the natural frequencies of the system increase, while the
amplitude of vibration decreases as a consequence of increasing the thickness
of the bearing.


title: Structure Based Extended Resolution for Constraint Programming

abstract:
  Nogood learning is a powerful approach to reducing search in Constraint
Programming (CP) solvers. The current state of the art, called Lazy Clause
Generation (LCG), uses resolution to derive nogoods expressing the reasons for
each search failure. Such nogoods can prune other parts of the search tree,
producing exponential speedups on a wide variety of problems. Nogood learning
solvers can be seen as resolution proof systems. The stronger the proof system,
the faster it can solve a CP problem. It has recently been shown that the proof
system used in LCG is at least as strong as general resolution. However,
stronger proof systems such as \emph{extended resolution} exist. Extended
resolution allows for literals expressing arbitrary logical concepts over
existing variables to be introduced and can allow exponentially smaller proofs
than general resolution. The primary problem in using extended resolution is to
figure out exactly which literals are useful to introduce. In this paper, we
show that we can use the structural information contained in a CP model in
order to introduce useful literals, and that this can translate into
significant speedups on a range of problems.


title:
Self-Organized Criticality in Asynchronously Tuned Elementary Cellular
  Automata

abstract:
  Self-organized criticality (SOC) reveals a mechanism by which a system is
autonomously evolved to be in a critical state without needing parameter
tuning. Whereas various biological systems are found to be in critical states
and the significance of SOC is being re-estimated, a simple model in a general
platform has not been established. Here, we present SOC in asynchronously tuned
elementary cellular automata (ECA), which was based on asynchronously updating
and tuning the consistency between local dual modes of transitions. This
duality was defined by adjunction, which can be ignored during synchronous
updates. Duality coupled with asynchronous updating can demonstrate that SOC
coincides with the criticality in a phase transition of asynchronous ECA with
respect to density decay.


title: Statistical inference for template-based protein structure prediction

abstract:
  Protein structure prediction is one of the most important problems in
computational biology. The most successful computational approach, also called
template-based modeling, identifies templates with solved crystal structures
for the query proteins and constructs three dimensional models based on
sequence/structure alignments. Although substantial effort has been made to
improve protein sequence alignment, the accuracy of alignments between
distantly related proteins is still unsatisfactory. In this thesis, I will
introduce a number of statistical machine learning methods to build accurate
alignments between a protein sequence and its template structures, especially
for proteins having only distantly related templates. For a protein with only
one good template, we develop a regression-tree based Conditional Random Fields
(CRF) model for pairwise protein sequence/structure alignment. By learning a
nonlinear threading scoring function, we are able to leverage the correlation
among different sequence and structural features. We also introduce an
information-theoretic measure to guide the learning algorithm to better exploit
the structural features for low-homology proteins with little evolutionary
information in their sequence profile. For a protein with multiple good
templates, we design a probabilistic consistency approach to thread the protein
to all templates simultaneously. By minimizing the discordance between the
pairwise alignments of the protein and templates, we are able to construct a
multiple sequence/structure alignment, which leads to better structure
predictions than any single-template based prediction.