title:
The ages of young star clusters, massive blue stragglers and the upper
  mass limit of stars: analysing age dependent stellar mass functions

abstract:
  Massive stars rapidly change their masses through strong stellar winds and
mass transfer in binary systems. We show that such mass changes leave
characteristic signatures in stellar mass functions of young star clusters
which can be used to infer their ages and to identify products of binary
evolution. We model the observed present day mass functions of the young
Galactic Arches and Quintuplet star clusters using our rapid binary evolution
code. We find that shaping of the mass function by stellar wind mass loss
allows us to determine the cluster ages to 3.5$\pm$0.7 Myr and 4.8$\pm$1.1 Myr,
respectively. Exploiting the effects of binary mass exchange on the cluster
mass function, we find that the most massive stars in both clusters are
rejuvenated products of binary mass transfer, i.e. the massive counterpart of
classical blue straggler stars. This resolves the problem of an apparent age
spread among the most luminous stars exceeding the expected duration of star
formation in these clusters. We perform Monte Carlo simulations to probe
stochastic sampling, which support the idea of the most massive stars being
rejuvenated binary products. We find that the most massive star is expected to
be a binary product after 1.0$\pm$0.7 Myr in Arches and after 1.7$\pm$1.0 Myr
in Quintuplet. Today, the most massive 9$\pm$3 stars in Arches and 8$\pm$3 in
Quintuplet are expected to be such objects. Our findings have strong
implications for the stellar upper mass limit and solve the discrepancy between
the claimed 150 $\mathrm{M}_\odot$ limit and observations of fours stars with
initial masses of 165-320 $\mathrm{M}_\odot$ in R136 and of SN 2007bi, which is
thought to be a pair-instability supernova from an initial 250
$\mathrm{M}_\odot$ star. Using the stellar population of R136, we revise the
upper mass limit to values in the range 200-500 $\mathrm{M}_\odot$.


title: Dissecting the Gamma-Ray Background in Search of Dark Matter

abstract:
  Several classes of astrophysical sources contribute to the approximately
isotropic gamma-ray background measured by the Fermi Gamma-Ray Space Telescope.
In this paper, we use Fermi's catalog of gamma-ray sources (along with
corresponding source catalogs at infrared and radio wavelengths) to build and
constrain a model for the contributions to the extragalactic gamma-ray
background from astrophysical sources, including radio galaxies, star-forming
galaxies, and blazars. We then combine our model with Fermi's measurement of
the gamma-ray background to derive constraints on the dark matter annihilation
cross section, including contributions from both extragalactic and galactic
halos and subhalos. The resulting constraints are competitive with the
strongest current constraints from the Galactic Center and dwarf spheroidal
galaxies. As Fermi continues to measure the gamma-ray emission from a greater
number of astrophysical sources, it will become possible to more tightly
constrain the astrophysical contributions to the extragalactic gamma-ray
background. We project that with 10 years of data, Fermi's measurement of this
background combined with the improved constraints on the astrophysical source
contributions will yield a sensitivity to dark matter annihilations that
exceeds the strongest current constraints by a factor of ~ 5 - 10.

categories: astro-ph.CO astro-ph.GA astro-ph.HE hep-ph


title:
Disk evolution in the solar neighborhood. I Disk frequencies from 1 to
  100 Myr

abstract:
  We study the evolution of circumstellar disks in 22 young (1 to 100 Myr)
nearby (within 500 pc) associations over the entire mass spectrum using
photometry covering from the optical to the mid-infrared. We compiled a catalog
of 2340 spectroscopically-confirmed members of these nearby associations. We
analyzed their spectral energy distributions and searched for excess related to
the presence of protoplanetary disks in a homogeneous way. Sensitivity limits
and spatial completeness were also considered. We derive disk fractions as
probed by mid-infrared excess in these regions. The unprecedented size of our
sample allows us to confirm the timescale of disk decay reported in the
literature and to find new trends. The fraction of excess sources increases
systematically if measured at longer wavelengths. Disk percentages derived
using different wavelength ranges should therefore be compared with caution.
The dust probed at 22-24 um evolves slower than that probed at shorter
wavelengths (3.4-12 um). Assuming an exponential decay, we derive a timescale
tau=4.2-5.8 Myr at 22-24 um for primordial disks, compared to 2-3 Myr at
shorter wavelength (3.4-12 um). Primordial disks disappear around 10 Myr,
matching in time a brief increase of the number of 'evolved' disks. The
increase in timescale of excess decay at longer wavelength is compatible with
inside-out disk clearing scenarios. The increased timescale of decay and larger
dispersion in the distribution of disk fractions at 22-24 um suggest that the
inner and outer zones evolve differently, the latter potentially following a
variety of evolutionary paths. The drop of primordial disks and the coincident
rise of evolved disks at 10 Myr are compatible with planet formation theories
suggesting that the disappearance of the gas is immediately followed by the
dynamical stirring of the disk.


title: Effective actions for anomalous hydrodynamics

abstract:
  We argue that an effective field theory of local fluid elements captures the
constraints on hydrodynamic transport stemming from the presence of quantum
anomalies in the underlying microscopic theory. Focussing on global current
anomalies for an arbitrary flavour group, we derive the anomalous constitutive
relations in arbitrary even dimensions. We demonstrate that our results agree
with the constraints on anomaly governed transport derived hitherto using a
local version of the second law of thermodynamics. The construction crucially
uses the anomaly inflow mechanism and involves a novel thermofield double
construction. In particular, we show that the anomalous Ward identities
necessitate non-trivial interaction between the two parts of the
Schwinger-Keldysh contour.


title: Critical Temperature of Interacting Bose Gases in Periodic Potentials

abstract:
  The superfluid transition of a repulsive Bose gas in the presence of a
sinusoidal potential which represents a simple-cubic optical lattice is
investigate using quantum Monte Carlo simulations. At the average filling of
one particle per well the critical temperature has a nonmonotonic dependence on
the interaction strength, with an initial sharp increase and a rapid
suppression at strong interactions in the vicinity of the Mott transition. In
an optical lattice the positive shift of the transition is strongly enhanced
compared to the homogenous gas. By varying the lattice filling we find a
crossover from a regime where the optical lattice has the dominant effect to a
regime where interactions dominate and the presence of the lattice potential
becomes almost irrelevant.


title: Holographic thermal field theory on curved spacetimes

abstract:
  The AdS/CFT correspondence relates certain strongly coupled CFTs with large
effective central charge $c_\text{eff}$ to semi-classical gravitational
theories with AdS asymptotics. We describe recent progress in understanding
gravity duals for CFTs on non-trivial spacetimes at finite temperature, both in
and out of equilibrium. Such gravity methods provide powerful new tools to
access the physics of these strongly coupled theories, which often differs
qualitatively from that found at weak coupling.
  Our discussion begins with basic aspects of AdS/CFT and progresses through
thermal CFTs on the Einstein Static Universe and on periodically identified
Minkowski spacetime. In the latter context we focus on states describing
so-called plasma balls, which become stable at large $c_\text{eff}$. We then
proceed to out-of-equilibrium situations associated with dynamical bulk black
holes. In particular, the non-compact nature of these bulk black holes allows
stationary solutions with non-Killing horizons that describe time-independent
flows of CFT plasma. As final a topic we consider CFTs on black hole
spacetimes. This discussion provides insight into how the CFT transports heat
between general heat sources and sinks of finite size. In certain phases the
coupling to small sources can be strongly suppressed, resulting in negligible
heat transport despite the presence of a deconfined plasma with sizeable
thermal conductivity. We also present a new result, explaining how this
so-called droplet behaviour is related to confinement via a change of conformal
frame.


title: The Habitable Epoch of the Early Universe

abstract:
  In the redshift range 100<(1+z)<137, the cosmic microwave background (CMB)
had a temperature of 273-373K (0-100 degrees Celsius), allowing early rocky
planets (if any existed) to have liquid water chemistry on their surface and be
habitable, irrespective of their distance from a star. In the standard LCDM
cosmology, the first star-forming halos within our Hubble volume started
collapsing at these redshifts, allowing the chemistry of life to possibly begin
when the Universe was merely 10-17 million years old. The possibility of life
starting when the average matter density was a million times bigger than it is
today argues against the anthropic explanation for the low value of the
cosmological constant.

categories: astro-ph.CO astro-ph.EP gr-qc hep-ph hep-th


title:
Exceptional Field Theory I: $E_{6(6)}$ covariant Form of M-Theory and
  Type IIB

abstract:
  We present the details of the recently constructed $E_{6(6)}$ covariant
extension of 11-dimensional supergravity. This theory requires a 5+27
dimensional spacetime in which the `internal' coordinates transform in the
$\bar{\bf 27}$ of $E_{6(6)}$. All fields are $E_{6(6)}$ tensors and transform
under (gauged) internal generalized diffeomorphisms. The `Kaluza-Klein' vector
field acts as a gauge field for the $E_{6(6)}$ covariant `E-bracket' rather
than a Lie bracket, requiring the presence of two-forms akin to the tensor
hierarchy of gauged supergravity. We construct the complete and unique action
that is gauge invariant under generalized diffeomorphisms in the internal and
external coordinates. The theory is subject to covariant section constraints on
the derivatives, implying that only a subset of the extra 27 coordinates is
physical. We give two solutions of the section constraints: the first preserves
GL(6) and embeds the action of the complete (i.e. untruncated) 11-dimensional
supergravity; the second preserves GL(5) x SL(2) and embeds complete type IIB
supergravity. As a by-product, we thus obtain an off-shell action for type IIB
supergravity.


title: On the Evolution of the Cosmic Ionizing Background

abstract:
  We study the observed cosmic ionizing background as a constraint on the
nature of the sources responsible for the reionization of the Universe. In
earlier work, we showed that extrapolations of the Ultra-Violet Luminosity
Function (LF) of Lyman Break Galaxies (LBGs) at fixed Lyman continuum photon
escape fraction are not able to reproduce the redshift evolution of this
background. Here, we employ extrapolations of the high-z LFs to describe the
contribution of LBGs to the ionizing photon rate, taking into account the
smoothing of the baryonic perturbations, due to the background itself (i.e. the
filtering mass), as well as a possible sharp increase of the escape fraction in
dwarf galaxies. Under the hypothesis of a dominant contribution of LBGs to
cosmic reionization, our results suggest that sources fainter than the current
observational limits should be characterised by escape fractions of the order
of ~0.1-0.3 (larger than the current estimates for bright galaxies) to account
for a z>6 reionization and the measured evolution of cosmic ionizing
background, at the same time. The contribution to the background from quasars
turns out to be relevant at z<3. Overall, our results support the case for
dedicated observations of faint galaxies in the rest-frame UV, in order to
better determine their physical properties. Observed escape fractions outside
our proposed range bear relevant consequences on the nature of the
astrophysical sources responsible for cosmic reionization and/or its buildup
process.


title:
Exploring Quasiparticles in High-Tc Cuprates Through Photoemission,
  Tunneling, and X-ray Scattering Experiments

abstract:
  One of the key challenges in the field of high-temperature superconductivity
is understanding the nature of fermionic quasiparticles. Experiments
consistently demonstrate the existence of a second energy scale, distinct from
the d-wave superconducting gap, that persists above the transition temperature
into the "pseudogap" phase. One common class of models relates this energy
scale to the quasiparticle gap due to a competing order, such as the
incommensurate "checkerboard" order observed in scanning tunneling microscopy
(STM) and resonant elastic X-ray scattering (REXS). In this paper we show that
these experiments are better described by identifying the second energy scale
with the inverse lifetime of quasiparticles. We develop a minimal
phenomenological model that allows us to quantitatively describe STM and REXS
experiments and discuss their relation with photoemission spectroscopy. Our
study refocuses questions about the nature of the pseudogap phase to the study
of the origin of inelastic scattering.


title:
Fully Automatic Liquid Metal Printer towards Personal Electronics
  Manufacture

abstract:
  Printed electronics is quickly emerging with tremendous value in a wide
variety of latest electrical engineering areas. However, restricted to the
rather limited conductive inks and printing strategies, the currently existing
electronics manufacturing tools are generally complicated, expensive, time,
material, water and energy consuming, and thus mainly restricted to the
industrial use. Here from an alternative way, the present article demonstrated
for the first time an entirely automatic printing system for personal
electronics manufacturing through introducing a composite liquid metal ink
delivery and printing mechanism to overcome the large surface tension facing
the solution, and integrating it with the notebook computer controlling
algorithm. With the developed printer, any desired electronically conductive
patterns spanning from single wires to various complex structures like
integrated circuit (IC), antenna, PCB, RFID, electronic greeting cards,
decoration arts, classical buildings (White House, Great Wall etc.) or more
do-it-yourself (DIY) circuits were demonstrated to be printed out in a moment
with high precision. And the total cost for the whole system has reached
personal affordability, which is hard to offer by so far the state of the art
technologies. Some fundamental fluid dynamics mechanisms related to the
proposed tapping mode enabled reliable printing and adhesion of the liquid
metal electronics on the flexible substrate was systematically disclosed
through theoretical interpretation and experimental measurements. This clearly
beyond-the-lab technology and pervasively available liquid metal printer opens
the way for large scale home level electronics making in the coming time.


title: Hidden order in hexagonal RMnO3 multiferroics

abstract:
  Hexagonal RMnO3 manganites are improper ferroelectrics in which the electric
polarization is a by-product of the tripling of the unit cell. In YMnO3, there
is a second transition at ~ 920K whose nature remains unexplained. We argue
that this transition can be seen as a sort of hidden order in which a residual
symmetry displayed by the trimerization order parameter is spontaneously
broken. This additional order gives rise to twelve structural domains instead
of six, and structural domain boundaries that can be either ferroelectric or
non-ferroelectric domain walls.


title: Non universality of entanglement convertibility

abstract:
  Recently, it has been suggested that operational properties connected to
quantum computation can be alternative indicators of quantum phase transitions.
In this work we systematically study these operational properties in 1D systems
that present phase transitions of different orders. For this purpose, we
evaluate the local convertibility between bipartite ground states. Our results
suggest that the operational properties, related to non-analyticities of the
entanglement spectrum, are good detectors of explicit symmetries of the model,
but not necessarily of phase transitions. We also show that thermodynamically
equivalent phases, such as Luttinger liquids, may display different
convertibility properties depending on the underlying microscopic model.


title: Propagation of Bessel and Airy beams through atmospheric turbulence

abstract:
  We investigate, through simulation, the modifications to Bessel and Airy
beams during propagation through atmospheric turbulence. We find that
atmospheric turbulence disrupts the quasi-non-diffracting nature of Bessel and
Airy beams when the transverse coherence length (Fried parameter) nears the
initial aperture diameter or diagonal respectively. The turbulence induced
transverse phase distortion limits the effectiveness of Bessel and Airy beams
for applications requiring propagation over long distances in the turbulent
atmosphere.


title:
D-instanton probe and the enhan\c{c}on mechanism from a quiver gauge
  theory

abstract:
  We study the $\mathcal N=2$ field theory realized by D3-branes on the
${\mathbb C}^2/{\mathbb Z}_2$ orbifold. The dual supergravity solution exhibits
a repulson singularity cured by the enhancon mechanism. By comparing the open
and closed string descriptions of a probe D-instanton, we can compute the exact
non-perturbative profile of the supergravity twisted field, which determines
the supergravity background. We then show how the non-trivial IR physics of the
field theory translates into the stringy effects that give rise to the enhancon
mechanism and the associated excision procedure.


title: Second Quantized Mathieu Moonshine

abstract:
  We study the second quantized version of the twisted twining genera of
generalized Mathieu moonshine, and prove that they give rise to Siegel modular
forms with infinite product representations. Most of these forms are expected
to have an interpretation as twisted partition functions counting 1/4 BPS dyons
in type II superstring theory on K3\times T^2 or in heterotic CHL-models. We
show that all these Siegel modular forms, independently of their possible
physical interpretation, satisfy an "S-duality" transformation and a
"wall-crossing formula". The latter reproduces all the eta-products of an older
version of generalized Mathieu moonshine proposed by Mason in the '90s.
Surprisingly, some of the Siegel modular forms we find coincide with the
multiplicative (Borcherds) lifts of Jacobi forms in umbral moonshine.


title:
High-energy and smoothness asymptotic expansion of the scattering
  amplitude for the Dirac equation and applications

abstract:
  We obtain an explicit formula for the diagonal singularities of the
scattering amplitude for the Dirac equation with short-range electromagnetic
potentials. Using this expansion we uniquely reconstruct an electric potential
and magnetic field from the high-energy limit of the scattering amplitude.
Moreover, supposing that the electric potential and magnetic field are
asymptotic sums of homogeneous terms we give the unique reconstruction
procedure for these asymptotics from the scattering amplitude, known for some
energy $E.$ Furthermore, we prove that the set of the averaged scattering
solutions to the Dirac equation is dense in the set of all solutions to the
Dirac equation that are in $L^{2}\left( \Omega\right) ,$ where $\Omega$ is any
connected bounded open set in $\mathbb{R}^{3}$ with smooth boundary, and we
show that if we know an electric potential and a magnetic field for
$\mathbb{R}^{3}\setminus\Omega$, then the scattering amplitude, given for some
energy $E$, uniquely determines these electric potential and magnetic field
everywhere in $\mathbb{R}^{3}$. Combining this uniqueness result with the
reconstruction procedure for the asymptotics of the electric potential and the
magnetic field we show that the scattering amplitude, known for some $E$,
uniquely determines a electric potential and a magnetic field, that are
asymptotic sums of homogeneous terms, which converges to the electric potential
and the magnetic field, respectively. Moreover, we discuss the symmetries of
the kernel of the scattering matrix, which follow from the parity,
charge-conjugation and time-reversal transformations for the Dirac operator.


title:
Efficient coordinate-descent for orthogonal matrices through Givens
  rotations

abstract:
  Optimizing over the set of orthogonal matrices is a central component in
problems like sparse-PCA or tensor decomposition. Unfortunately, such
optimization is hard since simple operations on orthogonal matrices easily
break orthogonality, and correcting orthogonality usually costs a large amount
of computation. Here we propose a framework for optimizing orthogonal matrices,
that is the parallel of coordinate-descent in Euclidean spaces. It is based on
{\em Givens-rotations}, a fast-to-compute operation that affects a small number
of entries in the learned matrix, and preserves orthogonality. We show two
applications of this approach: an algorithm for tensor decomposition that is
used in learning mixture models, and an algorithm for sparse-PCA. We study the
parameter regime where a Givens rotation approach converges faster and achieves
a superior model on a genome-wide brain-wide mRNA expression dataset.


title: Explicit estimates for solutions of nonlinear radiation-type problems

abstract:
  We establish the existence of weak solutions of a nonlinear radiation-type
boundary value problem for elliptic equation on divergence form with
discontinuous leading coefficient. Quantitative estimates play a crucial role
on the real applications. Our objective is the derivation of explicit
expressions of the involved constants in the quantitative estimates, the
so-called absolute or universal bounds. The dependence on the leading
coefficient and on the size of the spatial domain is precise.This work shows
that the expressions of those constants are not so elegant as we might expect.


title: Wave Function and Strange Correlator of Short Range Entangled states

abstract:
  We demonstrate the following conclusion: If $|\Psi\rangle$ is a $1d$ or $2d$
nontrivial short range entangled state, and $|\Omega \rangle$ is a trivial
disordered state defined on the same Hilbert space, then the following quantity
(so called strange correlator) $C(r, r^\prime) = \frac{\langle \Omega|\phi(r)
\phi(r^\prime) | \Psi\rangle}{\langle \Omega| \Psi\rangle}$ either saturates to
a constant or decays as a power-law in the limit $|r - r^\prime| \rightarrow
+\infty$, even though both $| \Omega\rangle$ and $| \Psi\rangle$ are quantum
disordered states with short-range correlation. $\phi(r)$ is some local
operator in the Hilbert space. This result is obtained based on both field
theory analysis, and also an explicit computation of $C(r, r^\prime)$ for four
different examples: $1d$ Haldane phase of spin-1 chain, $2d$ quantum spin Hall
insulator with a strong Rashba spin-orbit coupling, $2d$ spin-2 AKLT state on
the square lattice, and the $2d$ bosonic symmetry protected topological phase
with $Z_2$ symmetry. This result can be used as a diagnosis for short range
entangled states in $1d$ and $2d$. A possible diagnosis for $3d$ short range
entangled states is also proposed.


title:
A storage-based model of heterocyst commitment and patterning in
  cyanobacteria

abstract:
  When deprived of fixed nitrogen (fN), certain filamentous cyanobacteria
differentiate nitrogen-fixing heterocysts. There is a large and dynamic
fraction of stored fN in cyanobacterial cells, but its role in directing
heterocyst commitment has not been identified. We present an integrated
computational model of fN transport, cellular growth, and heterocyst commitment
for filamentous cyanobacteria. By including fN storage proportional to cell
length, but without any explicit cell-cycle effect, we are able to recover a
broad and late range of heterocyst commitment times and we observe a strong
indirect cell-cycle effect. We propose that fN storage is an important
component of heterocyst commitment and patterning in filamentous cyanobacteria.
The model allows us to explore both initial and steady-state heterocyst
patterns. The developmental model is hierarchical after initial commitment: our
only source of stochasticity is observed growth rate variability. Explicit
lateral inhibition allows us to examine $\Delta$patS, $\Delta$hetN, and
$\Delta$patN phenotypes. We find that $\Delta$patS leads to adjacent
heterocysts of the same generation, while $\Delta$hetN leads to adjacent
heterocysts only of different generations. With a shortened inhibition range,
heterocyst spacing distributions are similar to those in experimental
$\Delta$patN systems. Step-down to non-zero external fixed nitrogen
concentrations is also investigated.


title: Observational clues to the progenitors of Type-Ia supernovae

abstract:
  Type-Ia supernovae (SNe Ia) are important distance indicators, element
factories, cosmic-ray accelerators, kinetic-energy sources in galaxy evolution,
and endpoints of stellar binary evolution. It has long been clear that a SN Ia
must be the runaway thermonuclear explosion of a degenerate carbon-oxygen
stellar core, most likely a white dwarf (WD). However, the specific progenitor
systems of SNe Ia, and the processes that lead to their ignition, have not been
identified. Two broad classes of progenitor binary systems have long been
considered: single-degenerate (SD), in which a WD gains mass from a
non-degenerate star; and double-degenerate (DD), involving the merger of two
WDs. New theoretical work has enriched these possibilities with some
interesting updates and variants. We review the significant recent
observational progress in addressing the progenitor problem. We consider clues
that have emerged from the observed properties of the various proposed
progenitor populations, from studies of their sites, pre- and post-explosion,
from analysis of the explosions themselves, and from the measurement of event
rates. The recent nearby and well-studied event, SN 2011fe, has been
particularly revealing. The observational results are not yet conclusive, and
sometimes prone to competing theoretical interpretations. Nevertheless, it
appears that DD progenitors, long considered the underdog option, could be
behind some, if not all, SNe Ia. We point to some directions that may lead to
future progress.


title:
Stream Control Transmission Protocol (SCTP): Robust and Efficient for
  Data Centre Applications

abstract:
  Due to rapid advancement in modern technology, as one of the major concerns
is the stability of business. The organizations depend on their systems to
provide robust and faster processing of information for their operations.
Efficient data centers are key sources to handle these operations. If the
organizational system is not fully functional, the performance of organization
may be impaired or clogged completely. With the developments of real-time
applications into data centers for data communications, there is a need to use
an alternative of the standard TCP protocol to provide reliable data transfer.
Stream Control Transmission Protocol (SCTP) consists of several well built-in
characteristics that make it capable to work efficiently with real-time
applications. In this paper, we evaluate an optimized version of STCP. The
optimized version of SCTP is tested against a non optimized version of STCP and
TCP in a data center environment. Simulations of the protocols are carried
using NS2 simulator


title: Effects of Jets in the Flow Observables

abstract:
  The transverse momentum anisotropy of the particles produced in heavy ion
collisions is one of the most important experimental observable to investigate
the collective behavior of the systems created in such collisions. Recent
studies show that the complex nature of the system evolution, such as initial
condition fluctuations and jets, may lead to important effects in the flow
coefficients and, therefore, to misinterpretation of the results obtained. In
this study, we used simulated events produced with a hydrodynamic model which
allows inhomogeneous initial condition combined with proton-proton collisions
produced with the Pythia event generator to create a final set of particles to
be analyzed with the usual experimental flow calculation techniques. Although
this simplified approach is somehow unrealistic, since it does not include the
interaction of the jet with the medium, our results have shown a good agreement
of the behavior of the elliptic flow coefficient as a function of the
transverse momentum up to 6 GeV/c for Au+Au collisions at 200 GeV. Although
each model alone is not able to describe the full range, the combination of
both sets of particles as seen by the flow calculation techniques may be the
key to explain the behavior observed in experimental data.


title: Phase Transitions in Community Detection: A Solvable Toy Model

abstract:
  Recently, it was shown that there is a phase transition in the community
detection problem. This transition was first computed using the cavity method,
and has been proved rigorously in the case of $q=2$ groups. However, analytic
calculations using the cavity method are challenging since they require us to
understand probability distributions of messages. We study analogous
transitions in so-called "zero-temperature inference" model, where this
distribution is supported only on the most-likely messages. Furthermore,
whenever several messages are equally likely, we break the tie by choosing
among them with equal probability. While the resulting analysis does not give
the correct values of the thresholds, it does reproduce some of the qualitative
features of the system. It predicts a first-order detectability transition
whenever $q > 2$, while the finite-temperature cavity method shows that this is
the case only when $q > 4$. It also has a regime analogous to the "hard but
detectable" phase, where the community structure can be partially recovered,
but only when the initial messages are sufficiently accurate. Finally, we study
a semisupervised setting where we are given the correct labels for a fraction
$\rho$ of the nodes. For $q > 2$, we find a regime where the accuracy jumps
discontinuously at a critical value of $\rho$.

categories: cs.SI cond-mat.stat-mech physics.soc-ph stat.ML


title:
The Youngest Known X-ray Binary: Circinus X-1 and its Natal Supernova
  Remnant

abstract:
  Because supernova remnants are short lived, studies of neutron star X-ray
binaries within supernova remnants probe the earliest stages in the life of
accreting neutron stars. However, such objects are exceedingly rare: none were
known to exist in our Galaxy. We report the discovery of the natal supernova
remnant of the accreting neutron star Circinus X-1, which places an upper limit
of t < 4, 600 years on its age, making it the youngest known X-ray binary and a
unique tool to study accretion, neutron star evolution, and core collapse
supernovae. This discovery is based on a deep 2009 Chandra X-ray observation
and new radio observations of Circinus X-1. Circinus X-1 produces type I X-ray
bursts on the surface of the neutron star, indicating that the magnetic field
of the neutron star is small. Thus, the young age implies either that neutron
stars can be born with low magnetic fields or that they can rapidly become
de-magnetized by accretion. Circinus X-1 is a microquasar, creating
relativistic jets which were thought to power the arcminute scale radio nebula
surrounding the source. Instead, this nebula can now be attributed to
non-thermal synchrotron emission from the forward shock of the supernova
remnant. The young age is consistent with the observed rapid orbital evolution
and the highly eccentric orbit of the system and offers the chance to test the
physics of post-supernova orbital evolution in X-ray binaries in detail for the
first time.


title:
Quantum and thermal ionic motion, oxygen isotope effect, and
  superexchange distribution in La$_2$CuO$_4$

abstract:
  We study the zero-point and thermal ionic motion in La$_2$CuO$_4$ by means of
high-resolution neutron diffraction experiments. Our results demonstrate
anisotropic motion of O and to a lesser extent of Cu ions, both consistent with
the structure of coupled CuO$_6$ octahedra, and quantify the relative effects
of zero-point and thermal contributions to ionic motion. By substitution of
$^{18}$O, we find that the oxygen isotope effect on the lattice dimensions is
small and negative ($-0.01\%$), while the isotope effect on the ionic
displacement parameters is significant ($-6$ to $50\%$). We use our results as
input for theoretical estimates of the distribution of magnetic interaction
parameters, $J$, in an effective one-band model for the cuprate plane. We find
that ionic motion causes only small ($1\%$) effects on the average value
$\langle J\rangle$, which vary with temperature and O isotope, but results in
dramatic ($10$-$20\%$) fluctuations in $J$ values that are subject to
significant ($8$-$12\%$) isotope effects. We demonstrate that this motional
broadening of $J$ can have substantial effects on certain electronic and
magnetic properties in cuprates.


title:
Lepton Flavor Violation in the Standard Model with general Dimension-Six
  Operators

abstract:
  We study lepton flavor observables in the Standard Model (SM) extended with
all dimension-$6$ operators which are invariant under the SM gauge group. We
calculate the complete one-loop predictions to the radiative lepton decays
$\mu\to e\gamma$, $\tau \to \mu \gamma$ and $\tau\to e\gamma$ as well as to the
closely related anomalous magnetic moments and electric dipole moments of
charged leptons, taking into account all dimension-$6$ operators which can
generate lepton flavor violation. Also the 3-body flavor violating charged
lepton decays $\tau^\pm \to \mu^\pm \mu^+ \mu^-$, $\tau^\pm\to e^\pm e^+ e^- $,
$\tau^\pm \to e^\pm \mu^+ \mu^- $, $\tau^\pm \to \mu^\pm e^+ e^- $, $\tau^\pm
\to e^\mp \mu^\pm \mu^\pm$, $\tau^\pm \to \mu^\mp e^\pm e^\pm $ and $\mu^\pm
\to e^\pm e^+ e^-$ and the $Z^0$ decays $Z^0\to\ell_i^+\ell_j^-$ are
considered, taking into account all tree-level contributions.


title:
Cluster formation in molecular clouds: I. stellar populations, star
  formation rates, and ionizing radiation

abstract:
  We present a model for the radiative output of star clusters in the process
of star formation suitable for use in hydrodynamical simulations of radiative
feedback. Gas in a clump, defined as a region whose density exceeds 10^4 cm^-3,
is converted to stars via the random sampling of the Chabrier IMF. A star
formation efficiency controls the rate of star formation. We have completed a
suite of simulations which follow the evolution of accretion-fed clumps with
initial masses ranging from 0 to 10^5 M_sol and accretion rates ranging from
10^-5 to 10^-1 M_sol yr^-1. The stellar content is tracked over time which
allows the aggregate luminosity, ionizing photon rate, number of stars, and
star formation rate (SFR) to be determined. For a fiducial clump of 10^4 M_sol,
the luminosity is ~4x10^6 L_sol with a SFR of roughly 3x10^-3 M_sol yr^-1. We
identify two regimes in our model. The accretion-dominated regime obtains the
majority of its gas through accretion and is characterized by an increasing SFR
while the reservoir-dominated regime has the majority of its mass present in
the initial clump with a decreasing SFR. We show that our model can reproduce
the expected number of O stars, which dominate the radiative output of the
cluster. We find a nearly linear relationship between SFR and mass as seen in
observations. We conclude that our model is an accurate and straightforward way
to represent the output of clusters in hydrodynamical simulations with
radiative feedback.


title: Causality and local determinism versus quantum nonlocality

abstract:
  The entanglement and the violation of Bell and CHSH inequalities in spin
polarization correlation experiments (SPCE) is considered to be one of the
biggest mysteries of Nature and is called quantum nonlocality. In this paper we
show once again that this conclusion is based on imprecise terminology and on
the lack of understanding of probabilistic models used in various proofs of
Bell and CHSH theorems. These models are inconsistent with experimental
protocols used in SPCE. This is the only reason why Bell and CHSH inequalities
are violated. A probabilistic non-signalling description of SPCE, consistent
with quantum predictions, is possible and it depends explicitly on the context
of each experiment. It is also deterministic in the sense that the outcome is
determined by supplementary local parameters describing both a physical signals
and measuring instruments. The existence of such description gives additional
arguments that quantum theory is emergent from some more detailed theory
respecting causality and local determinism. If quantum theory is emergent then
there exist perhaps some fine structures in time-series of experimental data
which were not predicted by quantum theory. In this paper we explain how a
systematic search for such fine structures can be done. If such reproducible
fine structures were found it would show that quantum theory is not predictably
complete what would be a major discovery.


title:
Objective Identification of Informative Wavelength Regions in Galaxy
  Spectra

abstract:
  Understanding the diversity in spectra is the key to determining the physical
parameters of galaxies. The optical spectra of galaxies are highly convoluted
with continuum and lines which are potentially sensitive to different physical
parameters. Defining the wavelength regions of interest is therefore an
important question. In this work, we identify informative wavelength regions in
a single-burst stellar populations model by using the CUR Matrix Decomposition.
Simulating the Lick/IDS spectrograph configuration, we recover the widely used
Dn(4000), Hbeta, and HdeltaA to be most informative. Simulating the SDSS
spectrograph configuration with a wavelength range 3450-8350 Angstrom and a
model-limited spectral resolution of 3 Angstrom, the most informative regions
are: first region-the 4000 Angstrom break and the Hdelta line; second
region-the Fe-like indices; third region-the Hbeta line; fourth region-the G
band and the Hgamma line. A Principal Component Analysis on the first region
shows that the first eigenspectrum tells primarily the stellar age, the second
eigenspectrum is related to the age-metallicity degeneracy, and the third
eigenspectrum shows an anti-correlation between the strengths of the Balmer and
the Ca K and H absorptions. The regions can be used to determine the stellar
age and metallicity in early-type galaxies which have solar abundance ratios,
no dust, and a single-burst star formation history. The region identification
method can be applied to any set of spectra of the user's interest, so that we
eliminate the need for a common, fixed-resolution index system. We discuss
future directions in extending the current analysis to late-type galaxies.


title: A Multi-stage Collaborative 3D GIS to Support Public Participation

abstract:
  This paper presents a collaborative 3D GIS to support public participation.
Realizing that public-involved decision making is often a multi-stage process,
the proposed system is designed to provide coherent support for collaborations
in the different stages. We differentiate ubiquitous participation and
intensive participation, and identify their suitable application stages. The
proposed system, then, supports both of the two types of participation by
providing synchronous and asynchronous collaboration functionalities. Applying
the concept of Digital Earth, the proposed system also features a virtual
globe-based user interface. Such an interface integrates a variety of data,
functions and services into a unified virtual environment which is delivered to
both experts and public participants through the Internet. The system has been
designed as a general software framework, and can be tailored for specific
projects. In this study, we demonstrate it using a scene modeling case and
provide a preliminary evaluation towards its usability.


title: Singularity of type $D_4$ arising from four qubit systems

abstract:
  An intriguing correspondence between four-qubit systems and simple
singularity of type $D_4$ is established. We first consider an algebraic
variety $X$ of separable states within the projective Hilbert space
$\mathbb{P}(\mathcal{H})=\mathbb{P}^{15}$. Then, cutting $X$ with a specific
hyperplane $H$, we prove that the $X$-hypersurface, defined from the section
$X\cap H\subset X$, has an isolated singularity of type $D_4$; it is also shown
that this is the "worst-possible" isolated singularity one can obtain by this
construction. Moreover, it is demonstrated that this correspondence admits a
dual version by proving that the equation of the dual variety of $X$, which is
nothing but the Cayley hyperdeterminant of type $2\times 2\times 2\times 2$,
can be expressed in terms of the SLOCC invariant polynomials as the
discriminant of the miniversal deformation of the $D_4$-singularity.


title: Super-hydrodynamic limit in interacting particle systems

abstract:
  This paper is a follow-up of the work initiated in [3], where it has been
investigated the hydrodynamic limit of symmetric independent random walkers
with birth at the origin and death at the rightmost occupied site. Here we
obtain two further results: first we characterize the stationary states on the
hydrodynamic time scale and show that they are given by a family of linear
macroscopic profiles whose parameters are determined by the current reservoirs
and the system mass. Then we prove the existence of a super-hyrdrodynamic time
scale, beyond the hydrodynamic one. On this larger time scale the system mass
fluctuates and correspondingly the macroscopic profile of the system randomly
moves within the family of linear profiles, with the randomness of a Brownian
motion.

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


title:
Simple Bounds for Noisy Linear Inverse Problems with Exact Side
  Information

abstract:
  This paper considers the linear inverse problem where we wish to estimate a
structured signal $x$ from its corrupted observations. When the problem is
ill-posed, it is natural to make use of a convex function $f(\cdot)$ that
exploits the structure of the signal. For example, $\ell_1$ norm can be used
for sparse signals. To carry out the estimation, we consider two well-known
convex programs: 1) Second order cone program (SOCP), and, 2) Lasso. Assuming
Gaussian measurements, we show that, if precise information about the value
$f(x)$ or the $\ell_2$-norm of the noise is available, one can do a
particularly good job at estimation. In particular, the reconstruction error
becomes proportional to the "sparsity" of the signal rather than the ambient
dimension of the noise vector. We connect our results to existing works and
provide a discussion on the relation of our results to the standard
least-squares problem. Our error bounds are non-asymptotic and sharp, they
apply to arbitrary convex functions and do not assume any distribution on the
noise.


title: Dirac fermion time-Floquet crystal: manipulating Dirac points

abstract:
  We demonstrate how to control the spectra and current flow of Dirac electrons
in both a graphene sheet and a topological insulator by applying either two
linearly polarized laser fields with frequencies $\omega$ and $2\omega$ or a
monochromatic (one-frequency) laser field together with a spatially periodic
static potential(graphene/TI superlattice). Using the Floquet theory and the
resonance approximation, we show that a Dirac point in the electron spectrum
can be split into several Dirac points whose relative location in momentum
space can be efficiently manipulated by changing the characteristics of the
laser fields. In addition, the laser-field controlled Dirac fermion band
structure -- Dirac fermion time-Floquet crystal -- allows the manipulation of
the electron currents in graphene and topological insulators. Furthermore, the
generation of dc currents of desirable intensity in a chosen direction occurs
when applying the bi-harmonic laser field which can provide a straightforward
experimental test of the predicted phenomena.

categories: cond-mat.mes-hall cond-mat.str-el physics.optics quant-ph


title: The Dense Gas Mass Fraction of Molecular Clouds in the Milky Way

abstract:
  The mass fraction of dense gas within giant molecular clouds (GMCs) of the
Milky Way is investigated using 13CO data from the FCRAO Galactic Plane Surveys
and the Bolocam Galactic Plane Survey (BGPS) of 1.1 mm dust continuum emission.
A sample of 860 compact dust sources are selected from the BGPS catalog and
kinematically linked to 344 clouds of extended (>3') 13CO J=1-0 emission. Gas
masses are tabulated for the full dust source and subregions within the dust
sources with mass surface densities greater than 200 M_solar/pc^2, which are
assumed to be regions of enhanced volume density. Masses of the parent GMCs are
calculated assuming optically thin 13CO J=1-0 emission and LTE conditions. The
mean fractional mass of dust sources to host GMC mass is 0.11 (-0.06, +0.12).
The high column density subregions comprise 0.07 (-0.05, +0.13) of the mass of
the cloud. Owing to our assumptions, these values are upper limits to the true
mass fractions. The fractional mass of dense gas is independent of GMC mass and
gas surface density. The low dense gas mass fraction suggests that the
formation of dense structures within GMCs is the primary bottleneck for star
formation. The distribution of velocity differences between the dense gas and
the low density material along the line of sight is also examined. We find a
strong, centrally peaked distribution centered on zero velocity displacement.
This distribution of velocity differences is modeled with radially converging
flows towards the dense gas position that are randomly oriented with respect to
the observed line of sight. These models constrain the infall velocities to be
2-4 km/s for various flow configurations.


title:
Double ellipsoidal Fermi surface model of the normal state of
  ferromagnetic superconductors

abstract:
  We model the normal state of ferromagnetic superconductors with two general
ellipsoidal Fermi surfaces (FSs), one for each spin projection
$\sigma=\{\uparrow,\downarrow\}$, each with its ferromagnetically split
chemical potential $\mu_{\sigma}$ and its three distinct single particle
effective masses, $\{m_{i\sigma}\}$, the geometric mean of which is
$m_{\sigma}$. We study this model in the presence of an arbitrarily oriented
magnetic induction, ${\bf B}=\mu_{0}{\bf H}+{\bf M_{0}}$, where ${\bf M_{0}}$
includes the Ising-like spontaneous ferromagnetic order, which for URhGe is in
the $c$-axis direction above the superconducting transition temperature $T_c$.
We assume the low-$T$ total particle density $\Sigma_{\sigma} n_{\sigma}({\bf
B})$ to be independent of ${\bf B}$, and obtain a self-consistent asymptotic
expansion for $\sum_{\sigma}\Pi^{3/2}_{\sigma}({\bf B})$ in even powers of
${\bf B}$, where $\Pi_{\sigma}({\bf B})=m_{\sigma}({\bf B})\mu_{\sigma}({\bf
B})$. We assume that the $\mu_{\sigma}({\bf B})$ are linear in ${\bf B}$ for
both spins due to the Zeeman interaction and that the remaining even ${\bf B}$
dependence in the $\Pi_{\sigma}({\bf B})$ arises only from $m_{\downarrow}({\bf
B})$. Our analogous expression for the Sommerfeld constant $\gamma({\bf B})$
leads to good fits to the $\gamma({\bf H})$ data of Aoki and Flouquet [J. Phys.
Soc. Jpn. \textbf{81}, 011003 (2012)] obtained for the ferromagnetic
superconductor URhGe in the ferromagnetic, non-superconducting phase, with the
applied magnetic field ${\bf H}$ along each of the three crystallographic
directions. We discuss this model in terms of the reentrant superconducting
properties of URhGe and UCoGe. This model can be generalized to an arbitrary
number of ellipsoidal FSs.


title:
Quantum Systems based upon Galois Fields: from Sub-quantum to
  Super-quantum Correlations

abstract:
  In this talk we describe our recent work on discrete quantum theory based on
Galois fields. In particular, we discuss how discrete quantum theory sheds new
light on the foundations of quantum theory and we review an explicit model of
super-quantum correlations we have constructed in this context. We also discuss
the larger questions of the origins and foundations of quantum theory, as well
as the relevance of super-quantum theory for the quantum theory of gravity.


title: Generalized Blockmodeling of Valued Networks

abstract:
  The paper presents several approaches to generalized blockmodeling of valued
networks, where values of the ties are assumed to be measured on at least
interval scale. The first approach is a straightforward generalization of the
generalized blockmodeling of binary networks (Doreian et al., 2005) to valued
blockmodeling. The second approach is homogeneity blockmodeling. The basic idea
of homogeneity blockmodeling is that the inconsistency of an empirical block
with its ideal block can be measured by within block variability of appropriate
values. New ideal blocks appropriate for blockmodeling of valued networks are
presented together with definitions of their block inconsistencies.


title: Interactions of large amplitude solitary waves in viscous fluid conduits

abstract:
  The free interface separating an exterior, viscous fluid from an intrusive
conduit of buoyant, less viscous fluid is known to support strongly nonlinear
solitary waves due to a balance between viscosity-induced dispersion and
buoyancy-induced nonlinearity. The overtaking, pairwise interaction of weakly
nonlinear solitary waves has been classified theoretically for the Korteweg-de
Vries equation and experimentally in the context of shallow water waves, but a
theoretical and experimental classification of strongly nonlinear solitary wave
interactions is lacking. The interactions of large amplitude solitary waves in
viscous fluid conduits, a model physical system for the study of
one-dimensional, truly dissipationless, dispersive nonlinear waves, are
classified. Using a combined numerical and experimental approach, three classes
of nonlinear interaction behavior are identified: purely bimodal, purely
unimodal, and a mixed type. The magnitude of the dispersive radiation due to
solitary wave interactions is quantified numerically and observed to be beyond
the sensitivity of our experiments, suggesting that conduit solitary waves
behave as "physical solitons." Experimental data are shown to be in excellent
agreement with numerical simulations of the reduced model. Experimental movies
are available with the online version of the paper.


title: Classical Dynamics of a Thin Moving Mirror Interacting with a Laser

abstract:
  We analyze the classical dynamics of a system composed of a one-dimensional
cavity with a perfect, fixed mirror and a movable mirror with non-zero
transparency interacting with a monochromatic laser. The movable mirror can
deviate far from an equilibrium position, it is assumed to be thin so that it
is modelled by a delta function, and we use the exact modes of the complete
system. The transparency and the mirror-position dependent cavity resonance
frequencies are built into the modes and this allows us to deduce that the
radiation pressure force comes from a periodic potential with period half the
wavelength of the field. The exact modes and the radiation pressure potential
allow us to give intuitive physical interpretations of the dynamics of the
system and to obtain approximate analytic solutions for the motion of the
mirror. Three regimes are identified depending on the intensity of the field
and it is found that the dynamics can be qualitatively very different in each
of them with some regimes being very sensitive to the values of the parameters.
Moreover, we determine conditions when the Maxwell-Newton equations used to
describe the system constitute accurate approximations of the exact equations
governing the dynamics.


title: Dynamics of Trends and Attention in Chinese Social Media

abstract:
  There has been a tremendous rise in the growth of online social networks all
over the world in recent years. It has facilitated users to generate a large
amount of real-time content at an incessant rate, all competing with each other
to attract enough attention and become popular trends. While Western online
social networks such as Twitter have been well studied, the popular Chinese
microblogging network Sina Weibo has had relatively lower exposure. In this
paper, we analyze in detail the temporal aspect of trends and trend-setters in
Sina Weibo, contrasting it with earlier observations in Twitter. We find that
there is a vast difference in the content shared in China when compared to a
global social network such as Twitter. In China, the trends are created almost
entirely due to the retweets of media content such as jokes, images and videos,
unlike Twitter where it has been shown that the trends tend to have more to do
with current global events and news stories. We take a detailed look at the
formation, persistence and decay of trends and examine the key topics that
trend in Sina Weibo. One of our key findings is that retweets are much more
common in Sina Weibo and contribute a lot to creating trends. When we look
closer, we observe that most trends in Sina Weibo are due to the continuous
retweets of a small percentage of fraudulent accounts. These fake accounts are
set up to artificially inflate certain posts, causing them to shoot up into
Sina Weibo's trending list, which are in turn displayed as the most popular
topics to users.


title: Differential Games of Competition in Online Content Diffusion

abstract:
  Access to online contents represents a large share of the Internet traffic.
Most such contents are multimedia items which are user-generated, i.e., posted
online by the contents' owners. In this paper we focus on how those who provide
contents can leverage online platforms in order to profit from their large base
of potential viewers.
  Actually, platforms like Vimeo or YouTube provide tools to accelerate the
dissemination of contents, i.e., recommendation lists and other re-ranking
mechanisms. Hence, the popularity of a content can be increased by paying a
cost for advertisement: doing so, it will appear with some priority in the
recommendation lists and will be accessed more frequently by the platform
users.
  Ultimately, such acceleration mechanism engenders a competition among online
contents to gain popularity. In this context, our focus is on the structure of
the acceleration strategies which a content provider should use in order to
optimally promote a content given a certain daily budget. Such a best response
indeed depends on the strategies adopted by competing content providers. Also,
it is a function of the potential popularity of a content and the fee paid for
the platform advertisement service.
  We formulate the problem as a differential game and we solve it for the
infinite horizon case by deriving the structure of certain Nash equilibria of
the game.


title: Generalized Hilbert coefficients and Northcott's inequality

abstract:
  Let $R$ be a Cohen-Macaulay local ring of dimension $d$ with infinite residue
field. Let $I$ be an $R$-ideal that has analytic spread $\ell(I)=d$, $G_d$
condition and the Artin-Nagata property $AN^-_{d-2}$. We provide a formula
relating the length $\lambda(I^{n+1}/JI^{n})$ to the difference
$P_I(n)-H_I(n)$, where $J$ is a general minimal reduction of $I$, $P_I(n)$ and
$H_I(n)$ are the generalized Hilbert-Samuel polynomial and the generalized
Hilbert-Samuel function in the sense of C. Polini and Y. Xie. We then use it to
establish formulas to compute the higher generalized Hilbert coefficients of
$I$. As an application, we extend Northcott's inequality to non
$\mathfrak{m}$-primary ideals. When equality holds in the generalized
Northcott's inequality, the ideal $I$ enjoys nice properties. Indeed, in this
case, we prove that the reduction number of $I$ is at most one and the
associated graded ring of $I$ is Cohen-Macaulay. We also recover results of G.
Colom$\acute{{\rm e}}$-Nin, C. Polini, B. Ulrich and Y. Xie on the positivity
of the generalized first Hilbert coefficient $j_1(I)$. Our work extends that of
S. Huckaba, C. Huneke and A. Ooishi to ideals that are not necessarily
$\mathfrak{m}$-primary.


title: Wavelet-Based Scalar-on-Function Finite Mixture Regression Models

abstract:
  Classical finite mixture regression is useful for modeling the relationship
between scalar predictors and scalar responses arising from subpopulations
defined by the differing associations between those predictors and responses.
Here we extend the classical finite mixture regression model to incorporate
functional predictors by taking a wavelet-based approach in which we represent
both the functional predictors and the component-specific coefficient functions
in terms of an appropriate wavelet basis. In the wavelet representation of the
model, the coefficients corresponding to the functional covariates become the
predictors. In this setting, we typically have many more predictors than
observations. Hence we use a lasso-type penalization to perform variable
selection and estimation. We also consider an adaptive version of our
wavelet-based model. We discuss the specification of the model, provide a
fitting algorithm, and apply and evaluate our method using both simulations and
a real data set from a study of the relationship between cognitive ability and
diffusion tensor imaging measures in subjects with multiple sclerosis.


title: Spectral properties of cubic complex Pisot units

abstract:
  For a real number $\beta>1$, Erd\H{o}s, Jo\'o and Komornik study distances
between consecutive points in the set $X^m(\beta)=\bigl\{\sum_{j=0}^n a_j
\beta^j : n\in\mathbb N,\,a_j\in\{0,1,\dots,m\}\bigr\}$. Pisot numbers play a
crucial role for the properties of $X^m(\beta)$. Following the work of Za\"imi,
who considered $X^m(\gamma)$ with $\gamma\in\mathbb{C}\setminus\mathbb{R}$ and
$|\gamma|>1$, we show that for any non-real $\gamma$ and $m < |\gamma|^2-1$,
the set $X^m(\gamma)$ is not relatively dense in the complex plane.
  Then we focus on complex Pisot units with a positive real conjugate $\gamma'$
and $m > |\gamma|^2-1$. If the number $1/\gamma'$ satisfies Property (F), we
deduce that $X^m(\gamma)$ is uniformly discrete and relatively dense, i.e.,
$X^m(\gamma)$ is a Delone set. Moreover, we present an algorithm for
determining two parameters of the Delone set $X^m(\gamma)$ which are analogous
to minimal and maximal distances in the real case $X^m(\beta)$. For $\gamma$
satisfying $\gamma^3 + \gamma^2 + \gamma - 1 = 0$, explicit formulas for the
two parameters are given.


title: Homogenization of the one-dimensional wave equation

abstract:
  We present a method for two-scale model derivation of the periodic
homogenization of the one-dimensional wave equation in a bounded domain. It
allows for analyzing the oscillations occurring on both microscopic and
macroscopic scales. The novelty reported here is on the asymptotic behavior of
high frequency waves and especially on the boundary conditions of the
homogenized equation. Numerical simulations are reported.


title: The Optimal Mechanism in Differential Privacy: Multidimensional Setting

abstract:
  We derive the optimal $\epsilon$-differentially private mechanism for a
general two-dimensional real-valued (histogram-like) query function under a
utility-maximization (or cost-minimization) framework for the $\ell^1$ cost
function. We show that the optimal noise probability distribution has a
correlated multidimensional staircase-shaped probability density function.
Compared with the Laplacian mechanism, we show that in the high privacy regime
(as $\epsilon \to 0$), the Laplacian mechanism is approximately optimal; and in
the low privacy regime (as $\epsilon \to +\infty$), the optimal cost is
$\Theta(e^{-\frac{\epsilon}{3}})$, while the cost of the Laplacian mechanism is
$\frac{2\Delta}{\epsilon}$, where $\Delta$ is the sensitivity of the query
function. We conclude that the gain is more pronounced in the low privacy
regime. We conjecture that the optimality of the staircase mechanism holds for
vector-valued (histogram-like) query functions with arbitrary dimension, and
holds for many other classes of cost functions as well.


title:
Probing the Synthesis of Two-Dimensional Boron by First-Principles
  Computations

abstract:
  Boron synthesis, in theory: Although two-dimensional boron sheets have
attracted considerable interest because of their theoretically predicted
properties, synthesis of such sheets remains a challenge. The feasibility of
different synthetic methods for two-dimensional boron sheets was assessed using
first-principles calculations, possibly paving the way towards its application
in nanoelectronics.


title:
Observation of anisotropic fragmentation in methane subjected to
  femtosecond radiation

abstract:
  We present experimental results on the ionization/dissociation of methane in
femtosecond pulses of radiation. Angular and intensity dependent yields of
singly and doubly charged species were measured using an imaging mass
spectrometer. The measured data shows that all fragments yields exhibit some
degree of anisotropy as a result of them being preferably ejected parallel to
the polarization direction. Additionally, an anomalous perpendicular
fragmentation pattern is found for CH\-(2)\+(2+). We find evidence of multiple
dissociation mechanisms including statistical decay, field assisted
dissociation and Coulomb explosion.


title:
A Theory of Changes for Higher-Order Languages - Incrementalizing
  {\lambda}-Calculi by Static Differentiation

abstract:
  If the result of an expensive computation is invalidated by a small change to
the input, the old result should be updated incrementally instead of
reexecuting the whole computation. We incrementalize programs through their
derivative. A derivative maps changes in the program's input directly to
changes in the program's output, without reexecuting the original program. We
present a program transformation taking programs to their derivatives, which is
fully static and automatic, supports first-class functions, and produces
derivatives amenable to standard optimization.
  We prove the program transformation correct in Agda for a family of
simply-typed {\lambda}-calculi, parameterized by base types and primitives. A
precise interface specifies what is required to incrementalize the chosen
primitives.
  We investigate performance by a case study: We implement in Scala the program
transformation, a plugin and improve performance of a nontrivial program by
orders of magnitude.


title: Prioritizing Consumers in Smart Grid: A Game Theoretic Approach

abstract:
  This paper proposes an energy management technique for a consumer-to-grid
system in smart grid. The benefit to consumers is made the primary concern to
encourage consumers to participate voluntarily in energy trading with the
central power station (CPS) in situations of energy deficiency. A novel system
model motivating energy trading under the goal of social optimality is
proposed. A single-leader multiple-follower Stackelberg game is then studied to
model the interactions between the CPS and a number of energy consumers (ECs),
and to find optimal distributed solutions for the optimization problem based on
the system model. The CPS is considered as a leader seeking to minimize its
total cost of buying energy from the ECs, and the ECs are the followers who
decide on how much energy they will sell to the CPS for maximizing their
utilities. It is shown that the game, which can be implemented distributedly,
possesses a socially optimal solution, in which the benefits-sum to all
consumers is maximized, as the total cost to the CPS is minimized. Numerical
analysis confirms the effectiveness of the game.


title:
Transition in High and Low Temperature Superconductors as Bounded Bose
  Einstein Condensation

abstract:
  The superconducting transition in High Temperature Superconductors(HTS) has
not been understood. Traditional Bose Einstein Condensation(BEC) theory
provides Tc estimates that are many times higher than the experimental values.
The proposed model of Bounded Bose Einstein Condensation(BBEC) assumes that the
energy of a superconducting carrier in condensate is bounded by Fermi energy.
BBEC theory predicts Tc from the energetic balance that neglects any carrier
pairing term and assumes 3 dimensional (3D) superconducting transport in Low
Temperature Superconductors(LTS), and 2D superconducting transport channeled
near the nodes of the Fermi arcs in HTS. BBEC produces Tc scaling relations
that are approximated by semi-empirical laws, and provides Tc in agreement with
experimental data. This agreement in HTS shows the role of BBEC as the main
mechanism of superconducting transitions, indicates transport channeling
(possibly related to the stripes, and demonstrates a minor contribution into
the energetic balance from pairing or pairing above Tc (possibly related to the
pseudogap.


title: Relativistic MHD Simulations of Poynting Flux-Driven Jets

abstract:
  Relativistic, magnetized jets are observed to propagate to very large
distances in many Active Galactic Nuclei (AGN). We use 3D relativistic MHD
(RMHD) simulations to study the propagation of Poynting flux-driven jets in
AGN. These jets are assumed already being launched from the vicinity ($\sim
10^3$ gravitational radii) of supermassive black holes. Jet injections are
characterized by a model described in Li et al. (2006) and we follow the
propagation of these jets to ~ parsec scales. We find that these
current-carrying jets are always collimated and mildly relativistic. When
$\alpha$, the ratio of toroidal-to-poloidal magnetic flux injection, is large
the jet is subject to non-axisymmetric current-driven instabilities (CDI) which
lead to substantial dissipation and reduced jet speed. However, even with the
presence of instabilities, the jet is not disrupted and will continue to
propagate to large distances. We suggest that the relatively weak impact by the
instability is due to the nature of the instability being convective and the
fact that the jet magnetic fields are rapidly evolving on Alfv\'enic timescale.
We present the detailed jet properties and show that far from the jet launching
region, a substantial amount of magnetic energy has been transformed into
kinetic energy and thermal energy, producing a jet magnetization number $\sigma
< 1$. In addition, we have also studied the effects of a gas pressure supported
"disk" surrounding the injection region and qualitatively similar global jet
behaviors were observed. We stress that jet collimation, CDIs, and the
subsequent energy transitions are intrinsic features of current-carrying jets.


title:
Revised Stellar Properties of Kepler Targets for the Quarter 1-16
  Transit Detection Run

abstract:
  We present revised properties for 196,468 stars observed by the NASA Kepler
Mission and used in the analysis of Quarter 1-16 (Q1-Q16) data to detect and
characterize transiting exoplanets. The catalog is based on a compilation of
literature values for atmospheric properties (temperature, surface gravity, and
metallicity) derived from different observational techniques (photometry,
spectroscopy, asteroseismology, and exoplanet transits), which were then
homogeneously fitted to a grid of Dartmouth stellar isochrones. We use
broadband photometry and asteroseismology to characterize 11,532 Kepler targets
which were previously unclassified in the Kepler Input Catalog (KIC). We report
the detection of oscillations in 2,762 of these targets, classifying them as
giant stars and increasing the number of known oscillating giant stars observed
by Kepler by ~20% to a total of ~15,500 stars. Typical uncertainties in derived
radii and masses are ~40% and ~20%, respectively, for stars with photometric
constraints only, and 5-15% and ~10% for stars based on spectroscopy and/or
asteroseismology, although these uncertainties vary strongly with spectral type
and luminosity class. A comparison with the Q1-Q12 catalog shows a systematic
decrease in radii for M dwarfs, while radii for K dwarfs decrease or increase
depending on the Q1-Q12 provenance (KIC or Yonsei-Yale isochrones). Radii of
F-G dwarfs are on average unchanged, with the exception of newly identified
giants. The Q1-Q16 star properties catalog is a first step towards an improved
characterization of all Kepler targets to support planet occurrence studies.


title:
Mechanics of Tunable Helices and Geometric Frustration in Biomimetic
  Seashells

abstract:
  Helical structures are ubiquitous in nature and engineering, ranging from DNA
molecules to plant tendrils, from sea snail shells to nanoribbons. While the
helical shapes in natural and engineered systems often exhibit nearly uniform
radius and pitch, helical shell structures with changing radius and pitch, such
as seashells and some plant tendrils, adds to the variety of this family of
aesthetic beauty. Here we develop a comprehensive theoretical framework for
tunable helical morphologies, and report the first biomimetic seashell-like
structure resulting from mechanics of geometric frustration. In previous
studies, the total potential energy is everywhere minimized when the system
achieves equilibrium. In this work, however, the local energy minimization
cannot be realized because of the geometric incompatibility, and hence the
whole system deforms into a shape with a global energy minimum whereby the
energy in each segment may not necessarily be locally optimized. This novel
approach can be applied to develop materials and devices of tunable geometries
with a range of applications in nano/biotechnology.


title:
Positivity constraints on the low-energy constants of the chiral
  pion-nucleon Lagrangian

abstract:
  Positivity constraints on the pion-nucleon scattering amplitude are derived
in this article with the help of general S-matrix arguments, such as
analyticity, crossing symmetry and unitarity, in the upper part of Mandelstam
triangle, R. Scanning inside the region R, the most stringent bounds on the
chiral low energy constants of the pion-nucleon Lagrangian are determined. When
just considering the central values of the fit results from covariant baryon
chiral perturbation theory using extended-on-mass-shell scheme, it is found
that these bounds are well respected numerically both at O(p^3) and O(p^4)
level. Nevertheless, when taking the errors into account, only the O(p^4)
bounds are obeyed in the full error interval, while the bounds on O(p^3) fits
are slightly violated. If one disregards loop contributions, the bounds always
fail in certain regions of R. Thus, at a given chiral order these terms are not
numerically negligible and one needs to consider all possible contributions,
i.e., both tree-level and loop diagrams. We have provided the constraints for
special points in R where the bounds are nearly optimal in terms of just a few
chiral couplings, which can be easily implemented and employed to constrain
future analyses. Some issues about calculations with an explicit Delta(1232)
resonance are also discussed.


title: On permutations of Hardy-Littlewood-P\'olya sequences

abstract:
  Let ${\cal H}=(q_1, \ldots q_r)$ be a finite set of coprime integers and let
$n_1, n_2, \ldots$ denote the multiplicative semigroup generated by $\cal H$
and arranged in increasing order. The distribution of such sequences has been
studied intensively in number theory and they have remarkable probabilistic and
ergodic properties. For example, the asymptotic properties of the sequence
$\{n_kx\}$ are very similar to those of independent, identically distributed
random variables; here $\{\cdot \}$ denotes fractional part. However, the
behavior of this sequence depends sensitively on the generating elements of
$(n_k)$ and the combination of probabilistic and number-theoretic effects
results in a unique, highly interesting asymptotic behavior. In particular, the
properties of $\{n_kx\}$ are not permutation invariant, in contrast to i.i.d.
behavior. The purpose of this paper is to show that $\{n_kx\}$ satisfies a
strong independence property ("interlaced mixing"), enabling one to determine
the precise asymptotic behavior of permuted sums $S_N (\sigma)= \sum_{k=1}^N
f(n_{\sigma(k)} x)$. As we will see, the behavior of $S_N(\sigma)$ still
follows that of sums of independent random variables, but its growth speed
(depending on $\sigma$) is given by the classical G\'al function of Diophantine
approximation theory. Some examples describing the class of possible growth
functions are given.


title: Lacunary sequences and permutations

abstract:
  By a classical principle of analysis, sufficiently thin subsequences of
general sequences of functions behave like sequences of independent random
variables. This observation not only explains the remarkable properties of
lacunary trigonometric series, but also provides a powerful tool in many areas
of analysis. In contrast to "true" random processes, however, the probabilistic
structure of lacunary sequences is not permutation-invariant and the analytic
properties of such sequences can change radically after rearrangement. The
purpose of this paper is to survey some recent results of the authors on
permuted function series. We will see that rearrangement properties of lacunary
trigonometric series $\sum (a_k\cos n_kx+b_k \sin n_kx)$ and their nonharmonic
analogues $\sum c_k f(n_kx)$ are intimately connected with the number theoretic
properties of $(n_k)_{k \geq 1}$ and we will give a complete characterization
of permutational invariance in terms of the Diophantine properties of $(n_k)_{k
\geq 1}$. We will also see that in a certain statistical sense, permutational
invariance is the "typical" behavior of lacunary sequences.


title:
Differentiable classification of 4-manifolds with singular Riemannian
  foliations

abstract:
  In this paper, we first prove that any closed simply connected 4-manifold
that admits a decomposition into two disk bundles of rank greater than 1 is
diffeomorphic to one of the standard elliptic 4-manifolds: $\mathbb{S}^4$,
$\mathbb{CP}^2$, $\mathbb{S}^2\times\mathbb{S}^2$, or $\mathbb{CP}^2\#\pm
\mathbb{CP}^2$. As an application we prove that any closed simply connected
4-manifold admitting a nontrivial singular Riemannian foliation is
diffeomorphic to a connected sum of copies of standard $\mathbb{S}^4$,
$\pm\mathbb{CP}^2$ and $\mathbb{S}^2\times\mathbb{S}^2$. A classification of
singular Riemannian foliations of codimension 1 on all closed simply connected
4-manifolds is obtained as a byproduct. In particular, there are exactly 3
non-homogeneous singular Riemannian foliations of codimension 1, complementing
the list of cohomogeneity one 4-manifolds.


title: On the asymptotic behavior of weakly lacunary series

abstract:
  Let $f$ be a measurable function satisfying $$f(x+1)=f(x), \qquad \int_0^1
f(x) dx=0, \qquad \textrm{Var} ~f < + \infty,$$ and let $(n_k)_{k\ge 1}$ be a
sequence of integers satisfying $n_{k+1}/n_k \ge q >1$ $(k=1, 2, \ldots)$. By
the classical theory of lacunary series, under suitable Diophantine conditions
on $n_k$, $(f(n_kx))_{k\ge 1}$ satisfies the central limit theorem and the law
of the iterated logarithm. These results extend for a class of subexponentially
growing sequences $(n_k)_{k\ge 1}$ as well, but as Fukuyama (2009) showed, the
behavior of $f(n_kx)$ is generally not permutation-invariant, e.g. a
rearrangement of the sequence can ruin the CLT and LIL. In this paper we
construct an infinite order Diophantine condition implying the
permutation-invariant CLT and LIL without any growth conditions on $(n_k)_{k\ge
1}$ and show that the known finite order Diophantine conditions in the theory
do not imply permutation-invariance even if $f(x)=\sin 2\pi x$ and $(n_k)_{k\ge
1}$ grows almost exponentially. Finally we prove that, in a suitable
statistical sense, for almost all sequences $(n_k)_{k\ge 1}$ growing faster
than polynomially, $(f(n_kx))_{k\ge 1}$ has permutation-invariant behavior.


title: Co-compact entropy and its variational principle for non-compact spaces

abstract:
  The purpose of this paper is to generalize the variational principle, which
states that the topological entropy is equal to the supremum of the measure
theoretical entropies and also the minimum of the metric theoretical entropies,
to non-compact dynamical systems by utilizing the co-compact entropy. The
equivalence between positive co-compact entropy and the existence of
p-horseshoes over the real line is also proved. This implies a system over real
line with positive co-compact entropy contains a compact invariant subset.


title: Satisfaction is not absolute

abstract:
  We prove that the satisfaction relation $\mathcal{N}\models\varphi[\vec a]$
of first-order logic is not absolute between models of set theory having the
structure $\mathcal{N}$ and the formulas $\varphi$ all in common. Two models of
set theory can have the same natural numbers, for example, and the same
standard model of arithmetic $\langle\mathbb{N},{+},{\cdot},0,1,{\lt}\rangle$,
yet disagree on their theories of arithmetic truth; two models of set theory
can have the same natural numbers and the same arithmetic truths, yet disagree
on their truths-about-truth, at any desired level of the iterated
truth-predicate hierarchy; two models of set theory can have the same natural
numbers and the same reals, yet disagree on projective truth; two models of set
theory can have the same $\langle H_{\omega_2},{\in}\rangle$ or the same
rank-initial segment $\langle V_\delta,{\in}\rangle$, yet disagree on which
assertions are true in these structures.
  On the basis of these mathematical results, we argue that a philosophical
commitment to the determinateness of the theory of truth for a structure cannot
be seen as a consequence solely of the determinateness of the structure in
which that truth resides. The determinate nature of arithmetic truth, for
example, is not a consequence of the determinate nature of the arithmetic
structure $\mathbb{N}=\{0,1,2,\ldots\}$ itself, but rather, we argue, is an
additional higher-order commitment requiring its own analysis and
justification.


title: Unveiling the Massive Stars in the Galactic Center

abstract:
  We present our recent efforts to unveil and understand the origin of massive
stars outside the three massive star clusters in the Galactic Center. From our
HST/NICMOS survey of the Galactic Center, we have identified 180 Paschen-alpha
emitting sources, most of which should be evolved massive stars with strong
optically thin stellar winds. Recently, we obtained Gemini GNIRS/NIFS H- and
K-band spectra of eight massive stars near the Arches cluster. From their
radial velocities, ages and masses, we suggest that in our sample, two stars
are previous members of the Arches cluster, while other two stars embedded in
the H1/H2 HII regions formed in-situ.


title:
Solutions associated with the point symmetries of the hyperbolic Ernst
  equation

abstract:
  The continuous point symmetry algebra of the hyperbolic Ernst equation is
presented. In a second step the corresponding group transformations are
considered. Accordingly, the solutions of the hyperbolic Ernst equation that
are invariant under Lie point symmetries, are constructed from the related
invariant surface conditions. Furthermore, all these solutions are revealed to
be related to solutions of the Euler-Poisson-Darboux equation by a simple
coordinate transformation. The parallels of these results to coordinate
transformations, which are important in the context of colliding plane wave
space times, are pointed out.


title:
The Discovery of Cometary Activity in Near-Earth Asteroid (3552) Don
  Quixote

abstract:
  The near-Earth object (NEO) population, which mainly consists of fragments
from collisions between asteroids in the main asteroid belt, is thought to
include contributions from short-period comets as well. One of the most
promising NEO candidates for a cometary origin is near-Earth asteroid (3552)
Don Quixote, which has never been reported to show activity. Here we present
the discovery of cometary activity in Don Quixote based on thermal-infrared
observations made with the Spitzer Space Telescope in its 3.6 and 4.5 {\mu}m
bands. Our observations clearly show the presence of a coma and a tail in the
4.5 {\mu}m but not in the 3.6 {\mu}m band, which is consistent with molecular
band emission from CO2. Thermal modeling of the combined photometric data on
Don Quixote reveals a diameter of 18.4 (-0.4/+0.3) km and an albedo of 0.03
(-0.01/+0.02), which confirms Don Quixote to be the third-largest known NEO. We
derive an upper limit on the dust production rate of 1.9 kg s^-1 and derive a
CO2 gas production rate of (1.1+-0.1)10^26 molecules s^-1. Spitzer IRS
spectroscopic observations indicate the presence of fine-grained silicates,
perhaps pyroxene rich, on the surface of Don Quixote. Our discovery suggests
that CO2 can be present in near-Earth space over a long time. The presence of
CO2 might also explain that Don Quixote's cometary nature remained hidden for
nearly three decades.


title: Shape-dependent bounds on cell growth rates

abstract:
  I consider how cell shape and environmental geometry affect the rate of
nutrient capture and the consequent maximum growth rate of a cell, focusing on
rod-like species like \textit{E.\ coli}. Simple modeling immediately implies
that it is the elongated profiles of such cells that allows for them to grow --
as observed -- at exponential rates in nutrient-rich media. Growth is strongly
suppressed when nutrient capture is diffusion-limited: In three dimensions, the
length is bounded by $\log L \lesssim t^{1/2}$, and in lower dimensions growth
is algebraic. Similar bounds are easily obtained for other cell geometries,
groups of cells, \textit{etc}. Fits of experimental growth curves to such
bounds can be used to estimate various quantities of interest, including
generalized metabolic rates.


title: The Role of Source Coherence in Atom Interferometery

abstract:
  The role of source cloud spatial coherence in a Mach-Zehnder type atom
interferometer is experimentally investigated. The visibility and contrast of a
Bose-Einstein condensate (BEC) and three thermal sources with varying spatial
coherence are compared as a function of interferometer time. At short times,
the fringe visibility of a BEC source approaches 100 % nearly independent of pi
pulse efficiency, while thermal sources have fringe visibilities limited to the
mirror efficiency. More importantly for precision measurement systems, the BEC
source maintains interference at interferometer times significantly beyond the
thermal source.


title:
Dilepton emission in high-energy heavy-ion collisions with viscous
  hydrodynamics

abstract:
  The invariant mass spectrum and the elliptic flow of lepton pairs produced in
relativistic heavy-ion collisions at RHIC are studied with viscous
hydrodynamics. The effects of viscous corrections on dilepton observables are
explored. The lepton pairs originating from charm quarks evolving in the
viscous background are seen to be a good probe of quark energy loss and gain,
as quantified by the dilepton spectrum and by the dilepton elliptic flow.


title:
Formal Model of Web Service Composition: An Actor-Based Approach to
  Unifying Orchestration and Choreography

abstract:
  Web Service Composition creates new composite Web Services from the
collection of existing ones to be composed further and embodies the added
values and potential usages of Web Services. Web Service Composition includes
two aspects: Web Service orchestration denoting a workflow-like composition
pattern and Web Service choreography which represents an aggregate composition
pattern. There were only a few works which give orchestration and choreography
a relationship. In this paper, we introduce an architecture of Web Service
Composition runtime which establishes a natural relationship between
orchestration and choreography through a deep analysis of the two ones. Then we
use an actor-based approach to design a language called AB-WSCL to support such
an architecture. To give AB-WSCL a firmly theoretic foundation, we establish
the formal semantics of AB-WSCL based on concurrent rewriting theory for
actors. Conclusions that well defined relationships exist among the components
of AB-WSCL using a notation of Compositionality is drawn based on semantics
analysis. Our works can be bases of a modeling language, simulation tools,
verification tools of Web Service Composition at design time, and also a Web
Service Composition runtime with correctness analysis support itself.


title: Energy integrals and metric embedding theory

abstract:
  For some centrally symmetric convex bodies $K\subset \mathbb R^n$, we study
the energy integral $$ \sup \int_{K} \int_{K} \|x - y\|_r^{p}\, d\mu(x)
d\mu(y), $$ where the supremum runs over all finite signed Borel measures $\mu$
on $K$ of total mass one. In the case where $K = B_q^n$, the unit ball of
$\ell_q^n$ (for $1 < q \leq 2$) or an ellipsoid, we obtain the exact value or
the correct asymptotical behavior of the supremum of these integrals. We apply
these results to a classical embedding problem in metric geometry. We consider
in $\mathbb R^n$ the Euclidean distance $d_2$. For $0 < \alpha < 1$, we
estimate the minimum $R$ for which the snowflaked metric space $(K,
d_2^{\alpha})$ may be isometrically embedded on the surface of a Hilbert sphere
of radius $R$.


title:
Phase transitions, geometrothermodynamics and critical exponents of
  black holes with conformal anomaly

abstract:
  We investigate the phase transitions of black holes with conformal anomaly in
canonical ensemble from different perspectives. Some interesting and novel
phase transition phenomena have been discovered. Firstly, we discuss the
behavior of the specific heat and the inverse of the isothermal
compressibility. It is shown that there are striking differences in Hawking
temperature and phase structure between black holes with conformal anomaly and
those without it. In the case with conformal anomaly, there exists local
minimum temperature corresponding to the phase transition point. Phase
transitions take place not only from an unstable large black hole to a locally
stable medium black hole but also from an unstable medium black hole to a
locally stable small black hole. Secondly, we probe in details the dependence
of phase transitions on the choice of parameters. The results show that black
holes with conformal anomaly have much richer phase structure than those
without it. There would be two, only one or no phase transition points
depending on the parameters we have chosen. The corresponding parameter region
are derived both numerically and graphically. Thirdly, geometrothermodynamics
are built up to examine the phase structure we have discovered. It is shown
that Legendre invariant thermodynamic scalar curvature diverges exactly where
the specific heat diverges. Furthermore, critical behaviors are investigated by
calculating the relevant critical exponents. It is proved that these critical
exponents satisfy the thermodynamic scaling laws, leading to the conclusion
that critical exponents and the scaling laws can reserve even when we consider
conformal anomaly.


title:
Modes of asymmetry: the application of harmonic analysis to symmetric
  quantum dynamics and quantum reference frames

abstract:
  Finding the consequences of symmetry for open system quantum dynamics is a
problem with broad applications, including describing thermal relaxation,
deriving quantum limits on the performance of amplifiers, and exploring quantum
metrology in the presence of noise. The symmetry of the dynamics may reflect a
symmetry of the fundamental laws of nature, a symmetry of a low-energy
effective theory, or it may describe a practical restriction such as the lack
of a reference frame. In this paper, we apply some tools of harmonic analysis
together with ideas from quantum information theory to this problem. The
central idea is to study the decomposition of quantum operations---in
particular, states, measurements and channels---into different modes, which we
call modes of asymmetry. Under symmetric processing, a given mode of the input
is mapped to the corresponding mode of the output, implying that one can only
generate a given output if the input contains all of the necessary modes. By
defining monotones that quantify the asymmetry in a particular mode, we also
derive quantitative constraints on the resources of asymmetry that are required
to simulate a given asymmetric operation. We present applications of our
results for deriving bounds on the probability of success in nondeterministic
state transitions, such as quantum amplification, and a simplified formalism
for studying the degradation of quantum reference frames.


title:
Low-temperature fabrication of brown TiO2 with enhanced photocatalytic
  activities under visible light

abstract:
  Titanium dioxide is a photocatalytic substance of great practical importance.
However, with its bandgap in the ultraviolet (UV) regime, native forms
(undoped) of TiO2 generally exhibits poor photocatalytic activities under
visible light. Here we report a facile one-step low-temperature method to treat
native TiO2 with NaH in a solution-based protocol. The NaH treatment
effectively induces the Ti(III) species and oxygen vacancies into the TiO2 host
lattice, and enables the bandgap of TiO2 to be conveniently adjusted from the
UV region to the red end of the visible spectrum. The modified TiO2 exhibited
significantly enhanced photocatalytic capability under visible light, and lead
to faster photo-degradation of organic chemical material. Compared with other
ways to reduce the bandgap of TiO2, the approach reported here provides unique
advantages for safe, large-scale and economic production of narrow-bandgap TiO2
materials.


title: A quantum measure of the multiverse

abstract:
  It has been recently suggested that probabilities of different events in the
multiverse are given by the frequencies at which these events are encountered
along the worldline of a geodesic observer (the "watcher"). Here I discuss an
extension of this probability measure to quantum theory. The proposed extension
is gauge-invariant, as is the classical version of this measure. Observations
of the watcher are described by a reduced density matrix, and the frequencies
of events can be found using the decoherent histories formalism of Quantum
Mechanics (adapted to open systems). The quantum watcher measure makes
predictions in agreement with the standard Born rule of QM.


title:
A universal electromagnetic energy conversion adapter based on a
  metamaterial absorber

abstract:
  On the heels of metamaterial absorbers (MAs) which produce near perfect
electromagnetic (EM) absorption and emission, we propose a universal
electromagnetic energy conversion adapter (UEECA) based on MA. By choosing the
appropriate energy converting sensors, the UEECA is able to achieve near 100%
signal transfer ratio between EM energy and various forms of energy such as
thermal, DC electric, or higher harmonic EM energy. The inherited subwavelength
dimension and the EM field intensity enhancement can further empower UEECA in
many critical applications such as energy harvesting, solar cell, and nonlinear
optics. The principle of UEECA is understood with a transmission line model,
which further provides a design strategy that can incorporate a variety of
energy conversion devices. The concept is experimentally validated at a
microwave frequency with a signal transfer ratio of 96% by choosing an RF diode
as the energy converting sensor.


title:
ALMA will determine the spectroscopic redshift z>8 with FIR [O III]
  emission lines

abstract:
  We investigate the potential use of nebular emission lines in the rest-frame
far-infrared (FIR) for determining spectroscopic redshift of z>8 galaxies with
the Atacama Large Millimeter/sub-millimeter Array (ALMA). After making a line
emissivity model as a function of metallicity, especially for the [O III] 88
micron line which is likely to be the strongest FIR line from H II regions, we
predict the line fluxes from high-z galaxies based on a cosmological
hydrodynamics simulation of galaxy formation. Since the metallicity of galaxies
reaches at ~0.2 Zsun even at z>8 in our simulation, we expect the [O III] 88
micron line as strong as 1.3 mJy for 27 AB objects, which is detectable at a
high significance by <1 hour integration with ALMA. Therefore, the [O III] 88
micron line would be the best tool to confirm the spectroscopic redshifts
beyond z=8.


title:
Optimization of zero-delay mappings for distributed coding by
  deterministic annealing

abstract:
  This paper studies the optimization of zero-delay analog mappings in a
network setting that involves distributed coding. The cost surface is known to
be non-convex, and known greedy methods tend to get trapped in poor locally
optimal solutions that depend heavily on initialization. We derive an
optimization algorithm based on the principles of "deterministic annealing", a
powerful global optimization framework that has been successfully employed in
several disciplines, including, in our recent work, to a simple zero-delay
analog communications problem. We demonstrate strict superiority over the
descent based methods, as well as present example mappings whose properties
lend insights on the workings of the solution and relations with digital
distributed coding.


title: A Process Algebra for Games

abstract:
  Using formal tools in computer science to describe games is an interesting
problem. We give games, exactly two person games, an axiomatic foundation based
on the process algebra ACP (Algebra of Communicating Process). A fresh operator
called opponent's alternative composition operator (OA) is introduced into ACP
to describe game trees and game strategies, called GameACP. And its sound and
complete axiomatic system is naturally established. To model the outcomes of
games (the co-action of the player and the opponent), correspondingly in
GameACP, the execution of GameACP processes, another operator called playing
operator (PO) is extended into GameACP. We also establish a sound and complete
axiomatic system for PO. To overcome the new occurred non-determinacy
introduced by GameACP, we extend truly concurrent process algebra APTC for
games called GameAPTC. Finally, we give the correctness theorem between the
outcomes of games and the deductions of GameACP and GameAPTC processes.


title:
On the supersingular K3 surface in characteristic 5 with Artin invariant
  1

abstract:
  We present three interesting projective models of the supersingular K3
surface X in characteristic 5 with Artin invariant 1. For each projective
model, we determine smooth rational curves on X with the minimal degree and the
projective automorphism group. Moreover, by using the superspecial abelian
surface, we construct six sets of 16 disjoint smooth rational curves on X, and
show that they form a beautiful configuration.


title: Biophysical Fitness Landscapes for Transcription Factor Binding Sites

abstract:
  Evolutionary trajectories and phenotypic states available to cell populations
are ultimately dictated by intermolecular interactions between DNA, RNA,
proteins, and other molecular species. Here we study how evolution of gene
regulation in a single-cell eukaryote S. cerevisiae is affected by the
interactions between transcription factors (TFs) and their cognate genomic
sites. Our study is informed by high-throughput in vitro measurements of TF-DNA
binding interactions and by a comprehensive collection of genomic binding
sites. Using an evolutionary model for monomorphic populations evolving on a
fitness landscape, we infer fitness as a function of TF-DNA binding energy for
a collection of 12 yeast TFs, and show that the shape of the predicted fitness
functions is in broad agreement with a simple thermodynamic model of two-state
TF-DNA binding. However, the effective temperature of the model is not always
equal to the physical temperature, indicating selection pressures in addition
to biophysical constraints caused by TF-DNA interactions. We find little
statistical support for the fitness landscape in which each position in the
binding site evolves independently, showing that epistasis is common in
evolution of gene regulation. Finally, by correlating TF-DNA binding energies
with biological properties of the sites or the genes they regulate, we are able
to rule out several scenarios of site-specific selection, under which binding
sites of the same TF would experience a spectrum of selection pressures
depending on their position in the genome. These findings argue for the
existence of universal fitness landscapes which shape evolution of all sites
for a given TF, and whose properties are determined in part by the physics of
protein-DNA interactions.


title: Flat Thomas-Fermi artificial atoms

abstract:
  We consider two-dimensional (2D) "artificial atoms" confined by an axially
symmetric potential $V(\rho)$. Such configurations arise in circular quantum
dots and other systems effectively restricted to a 2D layer. Using the
semiclassical method, we present the first fully self-consistent and analytic
solution yielding equations describing the density distribution, energy, and
other quantities for any form of $V(\rho)$ and an arbitrary number of confined
particles. An essential and nontrivial aspect of the problem is that the 2D
density of states must be properly combined with 3D electrostatics. The
solution turns out to have a universal form, with scaling parameters
$\rho^2/R^2$ and $R/a_B^*$ ($R$ is the dot radius and $a_B^*$ is the effective
Bohr radius).

categories: cond-mat.mes-hall cond-mat.quant-gas physics.atm-clus physics.atom-ph