title: Interacting Random Walkers and Non-Equilibrium Fluctuations

abstract:
  We introduce a model of interacting Random Walk, whose hopping amplitude
depends on the number of walkers/particles on the link. The mesoscopic
counterpart of such a microscopic dynamics is a diffusing system whose
diffusivity depends on the particle density. A non-equilibrium stationary flux
can be induced by suitable boundary conditions, and we show indeed that it is
mesoscopically described by a Fourier equation with a density dependent
diffusivity. A simple mean-field description predicts a critical diffusivity if
the hopping amplitude vanishes for a certain walker density. Actually, we
evidence that, even if the density equals this pseudo-critical value, the
system does not present any criticality but only a dynamical slowing down. This
property is confirmed by the fact that, in spite of interaction, the particle
distribution at equilibrium is simply described in terms of a product of
Poissonians. For mesoscopic systems with a stationary flux, a very effect of
interaction among particles consists in the amplification of fluctuations,
which is especially relevant close to the pseudo-critical density. This agrees
with analogous results obtained for Ising models, clarifying that larger
fluctuations are induced by the dynamical slowing down and not by a genuine
criticality. The consistency of this amplification effect with altered coloured
noise in time series is also proved.


title: Higgs-Radion Mixing with Enhanced Di-Photon Signal

abstract:
  In the context of warped scenarios in which Standard Model (SM) fields are
allowed to propagate in the bulk, we revisit the possible mixing between the IR
localized Higgs field and the Radion graviscalar. The phenomenology of the
resulting mostly-Higgs field does not suffer important deviations with respect
to the case in which all the SM is localized in the IR brane (original
Higgs-Radion mixing scenario). On the contrary, the phenomenology of the
mostly-Radion field can present important differences with respect to the
original scenario. At the LHC, the most striking effect is now the possibility
of sizeable Radion decays into photons in a mass range well beyond the ZZ and
WW thresholds, not due to dramatically enhanced couplings to photons but to
suppressed couplings to massive fields.


title:
Quantum pumping and rectification effects in Aharonov-Bohm-Casher
  ring-dot systems

abstract:
  We study the time-dependent transport of charge and spin through a
ring-shaped region sequentially coupled to a weakly interacting quantum dot in
the presence of an Aharonov-Bohm flux and spin-orbit interaction. The
time-dependent modulation of the spin-orbit interaction, or of the
corresponding Aharonov-Casher flux, together with the modulation of the
dot-level induces an electrically pumped spin current even in absence of a
charge current. The results beyond the adiabatic regime show that an additional
rectification current proportional to \cos(\phi), being \phi the relative phase
between the time varying parameters, is generated. We discuss the relevance of
such term in connection with recent experiments on out-of-equilibrium quantum
dots.


title: Dynamics of f(R)-cosmologies containing Einstein static models

abstract:
  We study the dynamics of homogeneous isotropic FRW cosmologies with positive
spatial curvature in $f(R)$-gravity, paying special attention to the existence
of Einstein static models and only study forms of $f(R)=R^n$ for which these
static models have been shown to exist. We construct a compact state space and
identify past and future attractors of the system and recover a previously
discovered future attractor corresponding to an expanding accelerating model.
We also discuss the existence of universes which have both a past and future
bounce, a phenomenon which is absent in General Relativity.


title:
Secular dynamics of coplanar, non-resonant planetary system under the
  general relativity and quadrupole moment perturbations

abstract:
  We construct a secular theory of a coplanar system of N-planets not involved
in strong mean motion resonances, and which are far from collision zones.
Besides the point-to-point Newtonian mutual interactions, we consider the
general relativity corrections to the gravitational potential of the star and
the innermost planet, and also a modification of this potential by the
quadrupole moment and tidal distortion of the star. We focus on hierarchical
planetary systems. A survey regarding model parameters (the masses, semi-major
axes, spin rate of the star) reveals a rich and non-trivial dynamics of the
secular system. Our study is focused on its equilibria. Such solutions
predicted by the classic secular theory, which correspond to aligned (mode I)
or anti-aligned (mode II) apsides, may be strongly affected by the
gravitational corrections. The so called true secular resonance, which is a new
feature of the classic two-planet problem discovered by Michtchenko & Malhotra
(2004), may appear in other, different regions of the phase space of the
generalized model. We found bifurcations of mode II which emerge new, yet
unknown in the literature, secularly unstable equilibria and a complex
structure of the phase space. These equilibria may imply secularly unstable
orbital configurations even for nitially moderate eccentricities. The point
mass gravity corrections can affect the long term-stability in the secular time
scale, which may directly depend on the age of the host star through its spin
rate. We also analyze the secular dynamics of the upsilon Andromede system in
the realm of the generalized model. Also in this case of the three-planet
system, new secular equilibria may appear.


title:
Magnetization Process of the Classical Heisenberg Model on the
  Shastry-Sutherland Lattice

abstract:
  We investigate classical Heisenberg spins on the Shastry-Sutherland lattice
and under an external magnetic field. A detailed study is carried out both
analytically and numerically by means of classical Monte-Carlo simulations.
Magnetization pseudo-plateaux are observed around 1/3 of the saturation
magnetization for a range of values of the magnetic couplings. We show that the
existence of the pseudo-plateau is due to an entropic selection of a particular
collinear state. A phase diagram that shows the domains of existence of those
pseudo-plateaux in the $(h, T)$ plane is obtained.


title: The decline in the concentration of citations, 1900-2007

abstract:
  This paper challenges recent research (Evans, 2008) reporting that the
concentration of cited scientific literature increases with the online
availability of articles and journals. Using Thomson Reuters' Web of Science,
the present paper analyses changes in the concentration of citations received
(two- and five-year citation windows) by papers published between 1900 and
2005. Three measures of concentration are used: the percentage of papers that
received at least one citation (cited papers); the percentage of papers needed
to account for 20, 50 and 80 percent of the citations; and, the
Herfindahl-Hirschman index. These measures are used for four broad disciplines:
natural sciences and engineering, medical fields, social sciences, and the
humanities. All these measures converge and show that, contrary to what was
reported by Evans, the dispersion of citations is actually increasing.


title: Exploring Effective Three-body Forces

abstract:
  Topics related to the construction, phenomenological determination, and
effects of the effective three-body forces within the traditional nuclear shell
model approach are discussed. The manifestations of the three-body forces in
realistic nuclei in the 0f7/2 and 1s0d shell model valence spaces are explored.


title:
Dynamic Arrest in Polymer Melts: Competition between Packing and
  Intramolecular Barriers

abstract:
  We present molecular dynamics simulations of a simple model for polymer melts
with intramolecular barriers. We investigate structural relaxation as a
function of the barrier strength. Dynamic correlators can be consistently
analyzed within the framework of the Mode Coupling Theory (MCT) of the glass
transition. Control parameters are tuned in order to induce a competition
between general packing effects and polymer-specific intramolecular barriers as
mechanisms for dynamic arrest. This competition yields unusually large values
of the so-called MCT exponent parameter and rationalize qualitatively different
observations for simple bead-spring and realistic polymers. The systematic
study of the effect of intramolecular barriers presented here also establishes
a fundamental difference between the nature of the glass transition in polymers
and in simple glass-formers.


title:
Simple unified derivation and solution of Coulomb, Eckart and
  Rosen-Morse potentials in prepotential approach

abstract:
  The four exactly-solvable models related to non-sinusoidal coordinates,
namely, the Coulomb, Eckart, Rosen-Morse type I and II models are normally
being treated separately, despite the similarity of the functional forms of the
potentials, their eigenvalues and eigenfunctions. Based on an extension of the
prepotential approach to exactly and quasi-exactly solvable models proposed
previously, we show how these models can be derived and solved in a simple and
unified way.

categories: quant-ph hep-th math-ph math.MP math.SP nlin.SI


title: Mesons and diquarks in the CFL phase of dense quark matter

abstract:
  The spectrum of meson and diquark excitations of the color--flavor locked
(CFL) phase of dense quark matter is considered in the framework of the Nambu
-- Jona-Lasinio model. We have found that in this phase all Nambu--Goldstone
bosons are realized as scalar and pseudoscalar diquarks. Other diquark
excitations are resonances with mass value around 230 MeV. Mesons are stable
particles in the CFL phase. Their masses vs chemical potential lie in the
interval 300$\div$500 MeV.


title: Length scale of dynamic heterogeneity in polymer nanocomposites

abstract:
  Using X- ray photon correlation spectroscopy measurements on gold
nanoparticles embedded in polymethylmethacrylate we provide evidence for
existence of an intrinsic length scale for dynamic heterogeneity in polymer
nanocomposites similar to that in other soft materials.We also show how the
dynamics varies in a complex way with various parameters.


title: The Gas Temperature of Starless Cores in Perseus

abstract:
  In this paper we study the determinants of starless core temperatures in the
Perseus molecular cloud. We use NH3 (1,1) and (2,2) observations to derive core
temperatures (T_kin) and data from the COMPLETE Survey of Star Forming Regions
and the c2d Spitzer Legacy Survey for observations of the other core and
molecular cloud properties. The kinetic temperature distribution probed by NH3
is in the fairly narrow range of 9 - 15 K. We find that cores within the
clusters IC348 and NGC1333 are significantly warmer than "field" starless
cores, and T_kin is higher within regions of larger extinction-derived column
density. Starless cores in the field are warmer when they are closer to class
O/I protostars, but this effect is not seen for those cores in clusters. For
field starless cores, T_kin is higher in regions in which the 13CO linewidth
and the 1.1mm flux from the core are larger, and T_kin is lower when the the
peak column density within the core and average volume density of the core are
larger. There is no correlation between T_kin and 13CO linewidth, 1.1mm flux,
density or peak column density for those cores in clusters. The temperature of
the cloud material along the line of sight to the core, as measured by CO or
far-infrared emission from dust, is positively correlated with core temperature
when considering the collection of cores in the field and in clusters, but this
effect is not apparent when the two subsamples of cores are considered
separately.


title: Chemical functionalization of graphene

abstract:
  Experimental and theoretical results on chemical functionalization of
graphene are reviewed. Using hydrogenated graphene as a model system, general
principles of the chemical functionalization are formulated and discussed. It
is shown that, as a rule, 100% coverage of graphene by complex functional
groups (in contrast with hydrogen and fluorine) is unreachable. A possible
destruction of graphene nanoribbons by fluorine is considered. The
functionalization of infinite graphene and graphene nanoribbons by oxygen and
by hydrofluoric acid is simulated step by step.


title:
Torsion and the Gravity Dual of Parity Symmetry Breaking in AdS4/CFT3
  Holography

abstract:
  We study four dimensional gravity with a negative cosmological constant
deformed by the Nieh-Yan torsional topological invariant with a
spacetime-dependent coefficient. We find an exact solution of the Euclidean
system, which we call the torsion vortex, having two asymptotic AdS4 regimes
supported by a pseudoscalar with a kink profile. We propose that the torsion
vortex is the holographic dual of a three dimensional system that exhibits
distinct parity breaking vacua. The torsion vortex represents a (holographic)
transition between these distinct vacua. We expect that from the boundary point
of view, the torsion vortex represents a `domain wall' between the two distinct
vacua.
  From a bulk point of view, we point out an intriguing identification of the
parameters of the torsion vortex with those of an Abrikosov vortex in a Type I
superconductor. Following the analogy, we find that external Kalb-Ramond flux
then appears to support bubbles of flat spacetime within an asymptotically AdS
geometry.


title: Phase of the Fermion Determinant for QCD at Finite Chemical Potential

abstract:
  In this lecture we discuss various properties of the phase factor of the
fermion determinant for QCD at nonzero chemical potential. Its effect on
physical observables is elucidated by comparing the phase diagram of QCD and
phase quenched QCD and by illustrating the failure of the Banks-Casher formula
with the example of one-dimensional QCD. The average phase factor and the
distribution of the phase are calculated to one-loop order in chiral
perturbation theory. In quantitative agreement with lattice QCD results, we
find that the distribution is Gaussian with a width $\sim \mu T \sqrt V$ (for
$m_\pi \ll T \ll \Lambda_{\rm QCD}$). Finally, we introduce, so-called teflon
plated observables which can be calculated accurately by Monte Carlo even
though the sign problem is severe.


title: New Circumstellar Dust Creation in V838 Monocerotis

abstract:
  We report high spatial resolution 11.2 and 18.1 micron imaging of the
eruptive variable V838 Monocerotis, obtained with Gemini Observatory's Michelle
in 2007 March. The 2007 flux density of the unresolved stellar core is roughly
2 times brighter than that observed in 2004. We interpret these data as
evidence that V838 Mon has experienced a new circumstellar dust creation event.
We also report a gap of spatially extended thermal emission over radial
distances of 1860-93000 AU from the central source, which suggests that no
prior significant circumstellar dust production events have occurred within the
past 900-1500 years.


title:
Energy and system dependence of high-$p_T$ triggered two-particle
  near-side correlations

abstract:
  Previous studies have indicated that the near-side peak of high-$p_T$
triggered correlations can be decomposed into two parts, the \textit{Jet} and
the \textit{Ridge}. We present data on the yield per trigger of the
\textit{Jet} and the \textit{Ridge} from $d+Au$, $Cu+Cu$ and $Au+Au$ collisions
at $\sqrt{s_{NN}}$ = 62.4 GeV and 200 GeV and compare data on the \textit{Jet}
to PYTHIA 8.1 simulations for $p+p$. PYTHIA describes the \textit{Jet}
component up to a scaling factor, meaning that PYTHIA can provide a better
understanding of the \textit{Ridge} by giving insight into the effects of the
kinematic cuts. We present collision energy and system dependence of the
\textit{Ridge} yield, which should help distinguish models for the production
mechanism of the \textit{Ridge}.


title: Direct Mediation, Duality and Unification

abstract:
  It is well-known that in scenarios with direct gauge mediation of
supersymmetry breaking the messenger fields significantly affect the running of
Standard Model couplings and introduce Landau poles which are difficult to
avoid. This appears to remove any possibility of a meaningful unification
prediction and is often viewed as a strong argument against direct mediation.
We propose two ways that Seiberg duality can circumvent this problem. In the
first, which we call "deflected-unification", the SUSY-breaking hidden sector
is a magnetic theory which undergoes a duality to an electric phase, with fewer
elementary degrees of freedom coupled to the MSSM. This changes the
beta-functions of the MSSM gauge couplings so as to push their Landau poles
above the unification scale. We show that this scenario is realised for
recently suggested models of gauge mediation based on a metastable SCQD-type
hidden sector directly coupled to MSSM. The second possibility, which we call
"dual-unification", begins with the observation that, if the mediating fields
fall into complete SU(5) multiplets, then the MSSM+messengers exhibits a fake
unification at unphysical values of the gauge couplings. We show that, in known
examples of electric/magnetic duals, such a fake unification in the magnetic
theory reflects a real unification in the electric theory. We therefore propose
that the Standard Model could itself be a magnetic dual of some unknown
electric theory in which the true unification takes place. This scenario
maintains the unification prediction (and unification scale) even in the
presence of Landau poles in the magnetic theory below the GUT scale. We further
note that this dual realization of grand unification can explain why Nature
appears to unify, but the proton does not decay.


title: Hydrodynamical Velocity Fields in Planetary Nebulae

abstract:
  Based on axi-symmetric hydrodynamical simulations and 3D reconstructions with
Shape, we investigate the kinematic signatures of deviations from homologous
("Hubble-type") outflows in some typical shapes of planetary nebulae. We find
that, in most situations considered in our simulations, the deviations from a
Hubble-type flow are significant and observable. The deviations are systematic
and a simple parameterization of them considerably improves morpho-kinematical
models of the simulations. We describe such extensions to a homologous
expansion law that capture the global velocity structure of hydrodynamical
axi-symmetric nebulae during their wind-blown phase. It is the size of the
poloidal velocity component that strongly influences the shape of the position
velocity diagrams that are obtained, not so much the variation of the radial
component. The deviations increase with the degree of collimation of the nebula
and they are stronger at intermediate latitudes. We describe potential
deformations which these deviations might produce in 3D reconstructions that
assume "Hubble-type" outflows. The general conclusion is that detailed
morpho-kinematic observations and modeling of planetary nebulae can reveal
whether a nebula is still in a hydrodynamically active stage (windy phase) or
whether it has reached ballistic expansion.


title: High speed coherent one-way quantum key distribution prototype

abstract:
  We report the first real world implementation of a Quantum Key Distribution
(QKD) system over a 43dB-loss transmission line in the Swisscom fibre optic
network. The QKD system is capable of continuous and autonomous operation and
uses the coherent one-way (COW) protocol. This system brings together three key
concepts for future QKD systems: a simple high-speed protocol; high performance
detection; and integration, both at the component level as well for
connectivity with standard fibre networks. Here, we show laboratory and field
trial results for this system. The full prototype version uses InGaAs/InP
avalanche photodiodes (APDs) and was laboratory tested up to 150km, with a
10-hour exchange averaging around 2kbps of real-time distilled secret bits over
100km. In the field trials, we obtained average distribution rates, during 3
hours, of 2.5bps over a 43dB-loss line of 150km, when using superconducting
single photon detectors (SSPDs).


title: Searches and Prospects for Standard Model Higgs boson at the Tevatron

abstract:
  We report on results obtained at the Tevatron by the CDF and D0
collaborations up to June 2008 (2.4 fb-1), on searches for standard model (SM)
Higgs bosons having a high mass (135-200 GeV). High mass Higgs bosons decay
dominantly in WW and the presented searches are performed in the leptonic decay
modes of the W's. Both direct production (ppbar -> H) and associated production
(ppbar -> WH) are studied and eventually combined with all channels available
at the Tevatron. Prospects for SM Higgs searches with the full projected
Tevatron statistics are also given.


title: Checking Security Policy Compliance

abstract:
  Ensuring compliance of organizations to federal regulations is a growing
concern. This paper presents a framework and methods to verify whether an
implemented low-level security policy is compliant to a high-level security
policy. Our compliance checking framework is based on organizational and
security metadata to support refinement of high-level concepts to
implementation specific instances. Our work uses the results of refinement
calculus to express valid refinement patterns and their properties.
Intuitively, a low-level security policy is compliant to a high-level security
policy if there is a valid refinement path from the high-level security policy
to the low-level security policy. Our model is capable of detecting violations
of security policies, failures to meet obligations, and capability and modal
conflicts.


title:
Dimension and singularity theory for local rings of finite embedding
  dimension

abstract:
  In this paper, an algebraic theory for local rings of finite embedding
dimension is developed. Several extensions of (Krull) dimension are proposed,
which are then used to generalize singularity notions from commutative algebra.
Finally, variants of the homological theorems are shown to hold in equal
characteristic.
  This theory is then applied to Noetherian local rings in order to get: (i)
over a Cohen-Macaulay local ring, uniform bounds on the Betti numbers of a
Cohen-Macaulay module in terms of dimension and multiplicity, and similar
bounds for the Bass numbers of a finitely generated module; (ii) a
characterization for being respectively analytically unramified, analytically
irreducible, unmixed, quasi-unmixed, normal, Cohen-Macaulay, pseudo-rational,
or weakly F-regular in terms of certain uniform arithmetic behavior; (iii) in
mixed characteristic, the Improved New Intersection Theorem when the residual
characteristic or ramification index is large with respect to dimension (and
some other numerical invariants).


title: Galactic secondary positron flux at the Earth

abstract:
  Secondary positrons are produced by spallation of cosmic rays within the
interstellar gas. Measurements have been typically expressed in terms of the
positron fraction, which exhibits an increase above 10 GeV. Many scenarios have
been proposed to explain this feature, among them some additional primary
positrons originating from dark matter annihilation in the Galaxy. The PAMELA
satellite has provided high quality data that has enabled high accuracy
statistical analyses to be made, showing that the increase in the positron
fraction extends up to about 100 GeV. It is therefore of paramount importance
to constrain theoretically the expected secondary positron flux to interpret
the observations in an accurate way. We find the secondary positron flux to be
reproduced well by the available observations, and to have theoretical
uncertainties that we quantify to be as large as about one order of magnitude.
We also discuss the positron fraction issue and find that our predictions may
be consistent with the data taken before PAMELA. For PAMELA data, we find that
an excess is probably present after considering uncertainties in the positron
flux, although its amplitude depends strongly on the assumptions made in
relation to the electron flux. By fitting the current electron data, we show
that when considering a soft electron spectrum, the amplitude of the excess
might be far lower than usually claimed. We provide fresh insights that may
help to explain the positron data with or without new physical model
ingredients. PAMELA observations and the forthcoming AMS-02 mission will allow
stronger constraints to be aplaced on the cosmic--ray transport parameters, and
are likely to reduce drastically the theoretical uncertainties.


title:
The 3He(alpha,gamma)7Be S-factor at solar energies: the prompt gamma
  experiment at LUNA

abstract:
  The 3He(alpha,gamma)7Be process is a key reaction in both Big-Bang
nucleosynthesis and p-p chain of Hydrogen Burning in Stars. A new measurement
of the 3He(alpha,gamma)7Be cross section has been performed at the INFN Gran
Sasso underground laboratory by both the activation and the prompt gamma
detection methods. The present work reports full details of the prompt gamma
detection experiment, focusing on the determination of the systematic
uncertainty. The final data, including activation measurements at LUNA, are
compared with the results of the last generation experiments and two different
theoretical models are used to obtain the S-factor at solar energies.


title:
Construction of the Zero-Energy State of SU(2)-Matrix Theory: Near the
  Origin

abstract:
  We explicitly construct a (unique) Spin(9)xSU(2) singlet state, phi,
involving only the fermionic degrees of freedom of the supersymmetric
matrix-model corresponding to reduced 10-dimensional super Yang-Mills theory,
resp. supermembranes in 11-dimensional Minkowski space. Any non-singular
wavefunction annihilated by the 16 supercharges of SU(2) matrix theory must, at
the origin (where it is assumed to be non-vanishing) reduce to phi.


title: Spin(9) Average of SU(N) Matrix Models I. Hamiltonian

abstract:
  We apply a method of group averaging to states and operators appearing in
(truncations of) the Spin(9) x SU(N) invariant matrix models. We find that
there is an exact correspondence between the standard supersymmetric
Hamiltonian and the Spin(9) average of a relatively simple lower-dimensional
model.


title: Collective Molecular Dynamics in Proteins and Membranes

abstract:
  The understanding of dynamics and functioning of biological membranes and in
particular of membrane embedded proteins is one of the most fundamental
problems and challenges in modern biology and biophysics. In particular the
impact of membrane composition and properties and of structure and dynamics of
the surrounding hydration water on protein function is an upcoming hot topic,
which can be addressed by modern experimental and computational techniques.
Correlated molecular motions might play a crucial role for the understanding
of, for instance, transport processes and elastic properties, and might be
relevant for protein function. Experimentally that involves determining
dispersion relations for the different molecular components, i.e., the length
scale dependent excitation frequencies and relaxation rates. Only very few
experimental techniques can access dynamical properties in biological materials
on the nanometer scale, and resolve dynamics of lipid molecules, hydration
water molecules and proteins and the interaction between them. In this context,
inelastic neutron scattering turned out to be a very powerful tool to study
dynamics and interactions in biomolecular materials up to relevant nanosecond
time scales and down to the nanometer length scale. We review and discuss
inelastic neutron scattering experiments to study membrane elasticity and
protein-protein interactions of membrane embedded proteins.


title:
Inductive Limits of Subhomogeneous $C^*$-algebras with Hausdorff
  Spectrum

abstract:
  We consider unital simple inductive limits of generalized dimension drop
C*-algebras They are so-called ASH-algebras and include all unital simple
AH-algebras and all dimension drop $C^*$-algebras. Suppose that $A$ is one of
these C*-algebras. We show that $A\otimes Q$ has tracial rank no more than one,
where $Q$ is the rational UHF-algebra. As a consequence, we obtain the
following classification result: Let $A$ and $B$ be two unital simple inductive
limits of generalized dimension drop algebras with no dimension growth. Then
$A\cong B$ if and only if they have the same Elliott invariant.


title: CLT Variance Associated with Baxendale's SDE

abstract:
  Simple analysis of the leftmost eigenvalue of Ince's equation (a boundary
value problem with periodicity) resolves an open issue surrounding a stochastic
Lyapunov exponent. Numerical verification is also provided.


title: Coded Adaptive Linear Precoded Discrete Multitone Over PLC Channel

abstract:
  Discrete multitone modulation (DMT) systems exploit the capabilities of
orthogonal subcarriers to cope efficiently with narrowband interference, high
frequency attenuations and multipath fadings with the help of simple
equalization filters. Adaptive linear precoded discrete multitone (LP-DMT)
system is based on classical DMT, combined with a linear precoding component.
In this paper, we investigate the bit and energy allocation algorithm of an
adaptive LP-DMT system taking into account the channel coding scheme. A coded
adaptive LPDMT system is presented in the power line communication (PLC)
context with a loading algorithm which accommodates the channel coding gains in
bit and energy calculations. The performance of a concatenated channel coding
scheme, consisting of an inner Wei's 4-dimensional 16-states trellis code and
an outer Reed-Solomon code, in combination with the proposed algorithm is
analyzed. Theoretical coding gains are derived and simulation results are
presented for a fixed target bit error rate in a multicarrier scenario under
power spectral density constraint. Using a multipath model of PLC channel, it
is shown that the proposed coded adaptive LP-DMT system performs better than
coded DMT and can achieve higher throughput for PLC applications.


title:
Discovery, photometry, and astrometry of 49 classical nova candidates in
  M81 galaxy

abstract:
  This paper reports on a search for new classical nova candidates in the M81
galaxy based on archival, as well as recent, new images. We used images from
1999-2007 to search for optical transients in M81. The positions of the
identified classical nova candidates were used to study their spatial
distribution. Kolmogorov - Smirnov test (KS) and bottom-to-top (BTR) ratio
diagnostic were used to analyze the nova candidate distribution and
differentiate between the disk and the bulge populations. In total, 49
classical nova candidates were discovered. In this study, we present the
precise positions and photometry of these objects, plus the photometry of an
additional 9 classical nova candidates found by Neill and Shara (2004). With
our large sample, we find a different spatial distribution of classical nova
candidates when compared to the results of earlier studies. Also, an
extraordinarily bright nova was found and studied in detail.


title:
Simple Proof that the Usual Transformations of the Electric and Magnetic
  Fields are not the Lorentz Transformations and EDM Searches

abstract:
  The usual transformations of the three-dimensional (3D) fields E and B that
are found in [1] ([1] A. Einstein, Ann. Physik \17, 891 (1905)) are always
considered to be the relativistically correct Lorentz transformations (LT) of E
and B. However, as proved in, e.g., [2] ([2] T. Ivezi\'c, Found. Phys. Lett.
18, 301 (2005)), these transformations drastically differ from the LT of the
relativistically correct 4D electric and magnetic fields. In this paper a
simple proof of that difference will be presented and the consequences for EDM
experiments and for some quantum phase shifts experiments are briefly examined.
In all such experiments the usual 3D quantities, e.g., E, B, ... are measured
and their relativistically incorrect transformations are used, but not the
relativistically correct 4D geometric quantities, e.g., E^a, B^a, ... and their
LT.


title: Modeling the magnetic field in the protostellar source NGC 1333 IRAS 4A

abstract:
  Magnetic fields are believed to play a crucial role in the process of star
formation. We compare high-angular resolution observations of the submillimeter
polarized emission of NGC 1333 IRAS 4A, tracing the magnetic field around a
low-mass protostar, with models of the collapse of magnetized molecular cloud
cores. Assuming a uniform dust alignment efficiency, we computed the Stokes
parameters and synthetic polarization maps from the model density and magnetic
field distribution by integrations along the line-of-sight and convolution with
the interferometric response. The synthetic maps are in good agreement with the
data. The best-fitting models were obtained for a protostellar mass of 0.8
solar masses, of age 9e4 yr, formed in a cloud with an initial mass-to-flux
ratio ~2 times the critical value. The magnetic field morphology in NGC 1333
IRAS 4A is consistent with the standard theoretical scenario for the formation
of solar-type stars, where well-ordered, large-scale, rather than turbulent,
magnetic fields control the evolution and collapse of the molecular cloud cores
from which stars form.


title: Frames for supersymmetry

abstract:
  We explain how the redefinitions of supermultiplet component fields,
comprising what we call "frame shifts", can be used in conjuction with the
graphical technology of multiplet Adkinras to render manifest the reducibility
of off-shell representations of supersymmetry. This technology speaks to
possibility of organizing multiplet constraints in a way which complements and
extends the possibilities afforded by superspace methods.


title:
A confirmation of agreement of different approaches for scalar
  gauge-invariant metric perturbations during inflation

abstract:
  We revisit an extension of the well-known formalism for gauge-invariant
scalar metric fluctuations, to study the spectrums for both, the inflaton and
gauge invariant (scalar) metric fluctuations in the framework of a single field
inflationary model where the quasi-exponential expansion is driven by an
inflation which is minimally coupled to gravity. The proposal here examined is
valid also for fluctuations with large amplitude, but for cosmological scales,
where vector and tensor perturbations can be neglected and the fluid is
irrotacional.


title: Sweeping Algebraic Curves for Singular Solutions

abstract:
  Many problems give rise to polynomial systems. These systems often have
several parameters and we are interested to study how the solutions vary when
we change the values for the parameters. Using predictor-corrector methods we
track the solution paths. A point along a solution path is critical when the
Jacobian matrix is rank deficient. The simplest case of quadratic turning
points is well understood, but these methods no longer work for general types
of singularities. In order not to miss any singular solutions along a path we
propose to monitor the determinant of the Jacobian matrix. We examine the
operation range of deflation and relate the effectiveness of deflation to the
winding number. Computational experiments on systems coming from different
application fields are presented.


title: Dynamics of the heat semigroup on symmetric spaces

abstract:
  The aim of this paper is to show that the dynamics of $L^p$ heat semigroups
($p>2$) on a symmetric space of non-compact type is very different from the
dynamics of the $L^p$ heat semigroups if $p\leq 2$. To see this, it is shown
that certain shifts of the $L^p$ heat semigroups have a chaotic behavior if
$p>2$ and that such a behavior is not possible in the cases $p\leq 2$. These
results are compared with the corresponding situation for euclidean spaces and
symmetric spaces of compact type where such a behavior is not possible.


title: Star Clusters in M31: I. A Catalog and a Study of the Young Clusters

abstract:
  We present an updated catalog of 1300 objects in the field of M31, including
670 likely star clusters of various types. Archival images were inspected to
confirm cluster classifications where possible, but most of the classifications
were based on spectra taken of ~1000 objects with the Hectospec fiber
positioner and spectrograph on the 6.5m MMT. The spectra and images of young
clusters are analyzed in detail in this paper. Ages, reddenings and masses of
140 young clusters are derived by comparing the observed spectra and photometry
with model spectra. We find these to have masses as great as 10^5 with a median
of 10^4 M_sun, and a median age of 0.25 Gyr. Thus these clusters are similar in
mass to the LMC young massive clusters, and are in between Milky Way open
clusters and the globulars of M31 and the Milky Way. Most of the M31 young
clusters have the low concentration typical of Milky Way open clusters, and we
expect that most of these will be disrupted in the next Gyr, but a few have
high concentrations and will likely survive longer. The spatial distribution of
the young clusters is well correlated with the star-forming regions as mapped
out by mid-IR emission. A kinematic analysis likewise confirms the spatial
association of the young clusters with the young disk in M31.


title:
Nonresonant Raman and inelastic X-ray scattering in the
  charge-density-wave phase of the spinless Falicov-Kimball model

abstract:
  Nonresonant inelastic light and X-ray scattering is investigated for the
spinless Falicov-Kimball model on an infinite-dimensional hypercubic lattice
with a charge-density-wave phase at half filling. The many-body density of
states (DOS) is found for different values of the Coulomb repulsion $U$,
ranging from a dirty metal to a Mott insulator. At zero temperature, the charge
gap is exactly equal to $U$; increasing the temperature rapidly fills the gap
with subgap states. The nonresonant response function for Raman and inelastic
X-ray scattering shows peaks connected with transitions over the gap and
transitions that involve subgap states. In the case of X-ray scattering (when
both energy and momentum are transferred), the response function illustrates
features of dynamical screening (vertex corrections) in the different
(nonresonant) symmetry channels ($A_{\rm 1g}$ and $B_{\rm 1g}$). We also derive
and verify the first moment sum rules for the (nonresonant) Raman and inelastic
X-ray response functions.


title:
Survey of vibronic polarons (precursors or full blown) and their role in
  the universe: an enigma to be possibly solved by LHC

abstract:
  Vibronic polarons (charge carriers coupled to their produced Jahn-Teller
distortions) have been extended for some time in relevance to the buildup of
matter and the breakdown of supersymmetry at the early stages of the universe,
as well as to a number of well established though not fully understood
phenomena of everyday life, such as helical propagation, colossal
magneto-resistance, etc. We review some of the advances and suggest new ones.
Many of them can be verified by Large Hadron Collider (LHC) experiments.


title: Breaking of a metastable string at finite temperature

abstract:
  We consider the phase transition of a string with tension $\eps_1$ to a
string with a smaller tension $\eps_2$ at finite temperature. For sufficiently
small temperatures the transition proceeds through thermally catalyzed quantum
tunneling, and we calculate in arbitrary number of dimensions the thermal
catalysis factor. At $\eps_2=0$ the found formula for the decay rate also
describes a break up of a metastable string into two pieces.


title: Linear Monotone Subspaces of Locally Convex Spaces

abstract:
  The main focus of this paper is to study multi-valued linear monotone
operators in the contexts of locally convex spaces via the use of their
Fitzpatrick and Penot functions. Notions such as maximal monotonicity,
uniqueness, negative-infimum, and (dual-) representability are studied and
criteria are provided.


title: Mottness on a triangular lattice

abstract:
  We study the physics on the paramagnetic side of the phase diagram of the
cobaltates, $Na_{x}CoO_{2}$, with an implementation of cellular dynamical mean
field theory (CDMFT) with the non-crossing approximation (NCA) for the one-band
Hubbard model on a triangular lattice. At low doping we find that the low
energy physics is dominated by a quasi-dispersionless band. At half-filling, we
find a metal-insulator transition at $U_{c}=5.6\pm0.15t$ which depends weakly
on the cluster size. The onset of the metallic state occurs through the growth
of a coherence peak at the chemical potential. Away from half filling, in the
electron-doped regime, the system is metallic with a large, continuous Fermi
surface as seen experimentally. Upon hole doping, a quasi non-dispersing band
emerges at the top of the lower Hubbard band and controls the low-energy
physics. This band is a clear signature of non-Fermi liquid behavior and cannot
be captured by any weakly coupled approach. This quasi non-dispersive band,
which persists in a certain range of dopings, has been observed experimentally.
We also investigate the pseudogap phenomenon in the context of a triangular
lattice and we propose a new framework for discussing the pseudogap phenomena
in general. This framework involves a momentum-dependent characterization of
the low-energy physics and links the appearance of the pseudogap to a
reconstruction of the Fermi surface without invoking any long range order or
symmetry breaking. Within this framework we predict the existence of a
pseudogap for the two dimensional Hubbard model on a triangular lattice in the
weakly hole-doped regime.


title: Shot Noise Probing of Magnetic Ordering in Zigzag Graphene Nanoribbons

abstract:
  The nonequilibrium time-dependent fluctuations of charge current have
recently emerged as a sensitive experimental tool to probe ballistic transport
through evanescent wave functions introduced into clean wide and short graphene
strips by the attached metallic electrodes. We demonstrate that such
"pseudo-diffusive" shot noise can be substantially modified in zigzag graphene
nanoribbon (ZGNR) due to the topology of its edges responsible for localized
states that facilitate ferromagnetic ordering along the edge when Coulomb
interaction is taken into account. Thus, the shot noise enhancement of
unpolarized, and even more sensitively of spin-polarized, charge currents
injected into ZGNR will act as an all-electrical and edge-sensitive probe of
such low-dimensional magnetism.


title: Deconstructing Baryon Acoustic Oscillations: A Comparison of Methods

abstract:
  The Baryon Acoustic Oscillations (BAOs) or baryon wiggles which are present
in the galaxy power spectrum at scales 100-150Mpc/h are powerful features with
which to constrain cosmology. The potential of these probes is such that these
are now included as primary science goals in the planning of several future
galaxy surveys. However, there is not a uniquely defined BAO Method in the
literature but a range of implementations. We study the assumptions and
cosmological performances of three different BAO methods: the full Fourier
space power spectrum [P(k)], the `wiggles only' in Fourier space and the
spherical harmonics power spectrum [C(l)]. We contrast the power of each method
to constrain cosmology for two fiducial surveys taken from the Dark Energy Task
Force (DETF) report and equivalent to future ground and space based
spectroscopic surveys. We find that, depending on the assumptions used, the
dark energy Figure of Merit (FoM) can change by up to a factor of 35 for a
given fiducial model and survey. We compare our results with the DETF
implementation and, discuss the robustness of each probe, by quantifying the
dependence of the FoM with the wavenumber range. The more information used by a
method, the higher its statistical performance, but the higher its sensitivity
to systematics and implementations details.


title: Synthesis of Silver Colloids: Experiment and Computational Model

abstract:
  We summarize our recent results that model the formation of uniform spherical
silver colloids prepared by mixing iso-ascorbic acid and silver-amine complex
solutions in the absence of dispersants. We found that the experimental results
can be modeled effectively by the two-stage formation mechanism used previously
to model the preparation of colloidal gold spheres. The equilibrium
concentration of silver atoms and the surface tension of silver precursor
nanocrystals are both treated as free parameters, and the experimental reaction
time scale is fit by a narrow region of this two-parameter space. The kinetic
parameter required to match the final particle size is found to be very close
to that used previously in modeling the formation of uniform gold particles,
suggesting that similar kinetics governs the aggregation process. The model
also reproduces semi quantitatively the effects of temperature and solvent
viscosity on particle synthesis.


title:
Spectroscopic Confirmation of Two Massive Red-Sequence-Selected Galaxy
  Clusters at z ~ 1.2 in the SpARCS-North Cluster Survey

abstract:
  The Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is a deep
z'-band imaging survey covering the Spitzer SWIRE Legacy fields designed to
create the first large homogeneously-selected sample of massive clusters at z >
1 using an infrared adaptation of the cluster red-sequence method. We present
an overview of the northern component of the survey which has been observed
with CFHT/MegaCam and covers 28.3 deg^2. The southern component of the survey
was observed with CTIO/MOSAICII, covers 13.6 deg^2, and is summarized in a
companion paper by Wilson et al. (2008). We also present spectroscopic
confirmation of two rich cluster candidates at z ~ 1.2. Based on
Nod-and-Shuffle spectroscopy from GMOS-N on Gemini there are 17 and 28
confirmed cluster members in SpARCS J163435+402151 and SpARCS J163852+403843
which have spectroscopic redshifts of 1.1798 and 1.1963, respectively. The
clusters have velocity dispersions of 490 +/- 140 km/s and 650 +/- 160 km/s,
respectively which imply masses (M200) of (1.0 +/- 0.9) x 10^{14} M_{solar} and
(2.4 +/- 1.8) x 10^{14} M_{solar}. Confirmation of these candidates as bona
fide massive clusters demonstrates that two-filter imaging is an effective, yet
observationally efficient, method for selecting clusters at z > 1.


title:
Equilibrium initial data for moving puncture simulations: The stationary
  1+log slicing

abstract:
  We propose and explore a "stationary 1+log" slicing condition for the
construction of solutions to Einstein's constraint equations. For stationary
spacetimes, these initial data will give a stationary foliation when evolved
with "moving puncture" gauge conditions that are often used in black hole
evolutions. The resulting slicing is time-independent and agrees with the
slicing generated by being dragged along a time-like Killing vector of the
spacetime. When these initial data are evolved with moving puncture gauge
conditions, numerical errors arising from coordinate evolution are minimized.
In the construction of initial data for binary black holes it is often assumed
that there exists an approximate helical Killing vector that generates the
binary's orbit. We show that, unfortunately, 1+log slices that are stationary
with respect to such a helical Killing vector cannot be asymptotically flat,
unless the spacetime possesses an additional axial Killing vector.


title:
Column Densities Towards Three Bursting Low-Mass X-ray Binaries from
  High Resolution X-ray Spectroscopy

abstract:
  We measured the galactic hydrogen column densities to the neutron-star
binaries GX 17+2, 4U 1705-44, and 4U 1728-34 by modeling the Mg and Si
absorption edges found in high-resolution X-ray spectra obtained by the Chandra
X-ray Observatory. We found for GX 17+2, N_H = (2.38 +/- 0.12) x 10^22 cm^-2,
for 4U 1705-44, N_H = (2.44 +/- 0.09) x 10^22 cm^-2, and for 4U 1728-34, N_H =
(2.49 +/- 0.14) x 10^22 cm^-2. These values are in reasonable agreement with
the hydrogen column densities inferred earlier from modeling of the continuum
spectra of the sources. Our results can be used to constrain the uncertainties
of model parameters of the X-ray spectra of these sources that are correlated
to the uncertainties of the hydrogen column density. In the case of continuum
spectra obtained during thermonuclear X-ray bursts, they will significantly
reduce the uncertainties in the spectroscopically measured masses and radii of
the neutron stars.


title:
Discovery of High-Energy Gamma-Ray Pulsations from PSR J2021+3651 with
  AGILE

abstract:
  Discovered after the end of the Compton Gamma-Ray Observatory mission, the
radio pulsar PSR J2021+3651 was long considered a likely counterpart of the
high-energy gamma-ray source 2CG 075+00 = 3EG J2021+3716 = GeV J2020+3658, but
it could not be confirmed due to the lack of a contemporaneous radio pulsar
ephemeris to fold the sparse, archival gamma-ray photons. Here, we report the
discovery of gamma-ray pulsations from PSR J2021+3651 in the 100-1500 MeV range
using data from the AGILE satellite gathered over 8 months, folded on a densely
sampled, contemporaneous radio ephemeris obtained for this purpose at the Green
Bank Telescope. The gamma-ray pulse consists of two sharp peaks separated by
0.47+/-0.01 cycles. The single radio pulse leads the first gamma-ray peak by
0.165+/-0.010 cycles. These properties are similar to those of other gamma-ray
pulsars, and the phase relationship of the peaks can be interpreted in the
context of the outer-gap accelerator model for gamma-ray emission. Pulse-phase
resolved images show that there is only one dominant source, AGL J2020.5+3653 =
PSR J2021+3651 in the region previously containing confused sources 3EG
J2021+3716 and 3EG J2016+3657.


title:
Tools for Dissecting Supernova Remnants Observed with Chandra: Methods
  and Application to the Galactic Remnant W49B

abstract:
  We introduce methods to quantify the X-ray morphologies of supernova remnants
observed with the Chandra X-ray Telescope. These include a power-ratio
technique to measure morphological asymmetries, correlation-length analysis to
probe chemical segregation and distribution, and wavelet-transform analysis to
quantify X-ray substructure. We demonstrate the utility and accuracy of these
techniques on relevant synthetic data. Additionally, we show the methods'
capabilities by applying them to the 55-ks Chandra ACIS observation of the
galactic supernova remnant W49B. We analyze the images of prominent emission
lines in W49B and use the results to discern physical properties. We find that
the iron morphology is very distinct from the other elements: it is
statistically more asymmetric, more segregated, and has 25% larger emitting
substructures than the lighter ions. Comparatively, the silicon, sulfur, argon,
and calcium are well-mixed, more isotropic, and have smaller, equally-sized
emitting substructures. Based on fits of XMM-Newton spectra in regions
identified as iron rich and iron poor, we determine that the iron in W49B must
have been anisotropically ejected. We measure the abundance ratios in many
regions, and we find that large, local variations are persistent throughout the
remnant. We compare the mean, global abundance ratios to those predicted by
spherical and bipolar core-collapse explosions; the results are consistent with
a bipolar origin from a 25 solar mass progenitor. We calculate the filling
factor of iron from the volume of its emitting substructures, enabling more
precise mass estimates than previous studies. Overall, this work is a first
step toward rigorously describing the physical properties of supernova remnants
for comparison within and between sources.


title: The Mid-Infrared [SIV]/[NeII] versus [NeIII]/[NeII] Correlation

abstract:
  The mid-infrared ratio [NeIII]15.6mum/[NeII]12.8mum is a strong diagnostic of
the ionization state of emission line objects, due to its use of only strong
neon emission lines only weakly affected by extinction. However this ratio is
not available to ground-based telescopes as only a few spectroscopic windows
are available in the MIR. To deal with this problem we aimed to verify if there
exists a conversion law between ground-accessible, strong MIR line ratio
[SIV]/[NeII] and the diagnostic [NeIII]/[NeII] ratio that can serve as a
reference for future ground-based observations. We collated the [SIV]10.5mum,
[NeII]12.8mum, [NeIII]15.6\mum and [SIII]18.7mum emission line fluxes from a
wide range of sources in the rich Spitzer and ISO archives, and compared the
[NeIII]/[NeII], [SIV]/[SIII], and [SIV]/[NeII] ratios. We find a strong
correlation between the [SIV]/[NeII] and [\neiii]/[\neii] ratio, with a linear
fit of log([NeIII]/[NeII]) = 0.81log([SIV]/[NeII])+0.36, accurate to a factor
of ~2 over four orders of magnitude in the line ratios. This demonstrates
clearly the ability of ground-based infrared spectrographs to do ionization
studies of nebulae.


title:
Microlensing variability in the gravitationally lensed quasar QSO
  2237+0305 = the Einstein Cross. II. Energy profile of the accretion disk

abstract:
  We present the continuation of our long-term spectroscopic monitoring of the
gravitationally lensed quasar QSO 2237+0305. We investigate the chromatic
variations observed in the UV/optical continuum of both quasar images A and B,
and compare them with numerical simulations to infer the energy profile of the
quasar accretion disk. Our procedure combines the microlensing ray-shooting
technique with Bayesian analysis, and derives probability distributions for the
source sizes as a function of wavelength. We find that the effective caustic
crossing timescale is 4.0+/-1.0 months. Using a robust prior on the effective
transverse velocity, we find that the source responsible for the UV/optical
continuum has an energy profile well reproduced by a power-law R lambda^{zeta}
with zeta=1.2+/-0.3, where R is the source size responsible for the emission at
wavelength lambda. This is the first accurate, model-independent determination
of the energy profile of a quasar accretion disk on such small scales.


title: Summing the Instantons in Half-Twisted Linear Sigma Models

abstract:
  We study half-twisted linear sigma models relevant to (0,2) compactifications
of the heterotic string. Focusing on theories with a (2,2) locus, we examine
the linear model parameter space and the dependence of genus zero half-twisted
correlators on these parameters. We show that in a class of theories the
correlators and parameters separate into A and B types, present techniques to
compute the dependence, and apply these to some examples. These results should
bear on the mathematics of (0,2) mirror symmetry and the physics of the moduli
space and Yukawa couplings in heterotic compactifications.


title: Dipole Excitation of Dipositronium

abstract:
  The energy interval between the ground and the P-wave excited states of the
recently discovered positronium molecule Ps_2 is evaluated, including the
relativistic and the leading logarithmic radiative corrections, E_P-E_S = 0.181
586 7(8) a.u. The P-state, decaying usually via annihilation, is found to decay
into the ground state by an electric dipole transition 19 percent of the time.
Anticipated observation of this transition will provide insight into this
exotic system.


title:
Fluctuations in the High-Redshift Lyman-Werner Background: Close Halo
  Pairs as the Origin of Supermassive Black Holes

abstract:
  The earliest generation of stars and black holes must have established an
early 'Lyman-Werner' background (LWB) at high redshift, prior to the epoch of
reionization. Because of the long mean free path of photons with energies
E<13.6 eV, the LWB was nearly uniform. However, some variation in the LWB is
expected due to the discrete nature of the sources, and their highly clustered
spatial distribution. In this paper, we compute the probability distribution
function (PDF) of the LW flux that irradiates dark matter (DM) halos collapsing
at high-redshift (z~10). Our model accounts for (i) the clustering of DM halos,
(ii) Poisson fluctuations in the number of corresponding star forming galaxies,
and (iii) scatter in the LW luminosity produced by halos of a given mass
(calibrated using local observations). We find that > 99% of the DM halos are
illuminated by a LW flux within a factor of 2 of the global mean value.
However, a small fraction, ~1e-8 to 1e-6, of DM halos with virial temperatures
above 1e4 K have a close luminous neighbor within < 10 kpc, and are exposed to
a LW flux exceeding the global mean by a factor of > 20, or to J_(21,LW)> 1e3
(in units of 1e-21 erg/s/Hz/sr/cm^2). This large LW flux can photo--dissociate
H_2 molecules in the gas collapsing due to atomic cooling in these halos, and
prevent its further cooling and fragmentation. Such close halo pairs therefore
provide possible sites in which primordial gas clouds collapse directly into
massive black holes (M_BH~ 1e4 - 1e6 M_sun), and subsequently grow into
supermassive (M_BH > 1e9 M_sun) black holes by z~6.


title:
Pressure Effects in Supercooled Water: Comparison between a 2D Model of
  Water and Experiments for Surface Water on a Protein

abstract:
  Experiments in bulk water confirm the existence of two local arrangements of
water molecules with different densities, but, because of inevitable freezing
at low temperature $T$, can not ascertain whether the two arrangements separate
in two phases. To avoid the freezing, new experiments measure the dynamics of
water at low $T$ on the surface of proteins, finding a crossover from a
non-Arrhenius regime at high $T$ to a regime that is approximately Arrhenius at
low $T$. Motivated by these experiments, Kumar et al. [Phys. Rev. Lett. 100,
105701 (2008)] investigated, by Monte Carlo simulations and mean field
calculations, the relation of the dynamic crossover with the coexistence of two
liquid phases in a cell model for water and predict that: (i) the dynamic
crossover is isochronic, i.e. the value of the crossover time $\tau_{\rm L}$ is
approximately independent of pressure $P$; (ii) the Arrhenius activation energy
$E_{\rm A}(P)$ of the low-$T$ regime decreases upon increasing $P$; (iii) the
temperature $T^*(P)$ at which $\tau$ reaches a fixed macroscopic time
$\tau^*\geq \tau_{\rm L}$ decreases upon increasing $P$; in particular, this is
true also for the crossover temperature $T_{\rm L}(P)$ at which $\tau=\tau_{\rm
L}$. Here, we compare these predictions with recent quasi elastic neutron
scattering (QENS) experiments performed by X.-Q. Chu {\it et al.} on hydrated
proteins at different values of $P$. We find that the experiments are
consistent with these three predictions.


title: Analysis of Enhanced Two-Photon Absorption in Tapered Optical Fibers

abstract:
  We analyze the rate of two-photon absorption in tapered optical fibers with
diameters less than the wavelength of the incident light. The rate of
two-photon absorption is shown to be enhanced due to the small mode volume of
the tapered fiber and the relatively large overlap of the evanescent field with
an atomic vapor that surrounds the tapered region. The two-photon absorption
rate is optimized as a function of the diameter of the tapered region.


title: Strange Particle Production at RHIC

abstract:
  We report STAR measurements of mid-rapidity yields for the $\Lambda$,
$\bar{\Lambda}$, $K^{0}_{S}$, $\Xi^{-}$, $\bar{\Xi}^{+}$, $\Omega^{-}$, and
$\bar{\Omega}^{+}$ particles in Cu+Cu and Au+Au $\sqrt{s_{NN}} = 200$ GeV
collisions. We show that at a given number of participating nucleons, bulk
strangeness production is higher in Cu+Cu collisions compared to Au+Au
collisions at the same center of mass energy, counter to predictions from the
Canonical formalism. We compare both the Cu+Cu and Au+Au yields to AMPT and
EPOS predictions, and find they reproduce key qualitative aspects of the data.
Finally, we investigate other scaling parameters and find bulk strangeness
production for both the measured data and theoretical predictions, scales
better with the number participants that undergo more than one collision.


title:
Ion Temperatures in the Low Solar Corona: Polar Coronal Holes at Solar
  Minimum

abstract:
  In the present work we use a deep-exposure spectrum taken by the SUMER
spectrometer in a polar coronal hole in 1996 to measure the ion temperatures of
a large number of ions at many different heights above the limb between 0.03
and 0.17 solar radii. We find that the measured ion temperatures are almost
always larger than the electron temperatures and exhibit a non-monotonic
dependence on the charge-to-mass ratio. We use these measurements to provide
empirical constraints to a theoretical model of ion heating and acceleration
based on gradually replenished ion-cyclotron waves. We compare the wave power
required to heat the ions to the observed levels to a prediction based on a
model of anisotropic magnetohydrodynamic turbulence. We find that the empirical
heating model and the turbulent cascade model agree with one another, and
explain the measured ion temperatures, for charge-to-mass ratios smaller than
about 0.25. However, ions with charge-to-mass ratios exceeding 0.25 disagree
with the model; the wave power they require to be heated to the measured ion
temperatures shows an increase with charge-to-mass ratio (i.e., with increasing
frequency) that cannot be explained by a traditional cascade model. We discuss
possible additional processes that might be responsible for the inferred
surplus of wave power.


title:
Effect of the tetrahedral distortion on the electronic properties of
  iron-pnictides

abstract:
  We study the dependence of the electronic structure of iron pnictides on the
angle formed by the arsenic-iron bonds. Within a Slater-Koster tight binding
model which captures the correct symmetry properties of the bands, we show that
the density of states and the band structure are sensitive to the distortion of
the tetrahedral environment of the iron atoms. This sensitivity is extremely
strong in a two-orbital (d_xz, d_yz) model due to the formation of a flat band
around the Fermi level. Inclusion of the d_xy orbital destroys the flat band
while keeping a considerable angle dependence in the band structure.


title:
Longitudinal parity-violating asymmetry in hadronic decays of weak
  bosons in polarized proton collisions

abstract:
  We investigate the possible measurement of parity-violating spin asymmetries
in jet pair production in proton-proton collisions at the Brookhaven
Relativistic Heavy Ion Collider (RHIC), with the goal to constrain
longitudinally polarized quark and antiquark distribution functions. A
measurable asymmetry could be observed in the vicinity of the massive weak W
boson resonance, where the parity-violating signal appears above the
parity-conserving background and is enhanced by interference of the strong and
electroweak production amplitudes. We discuss the potential for such
measurements, perhaps the first opportunity to measure a parity-violating
asymmetry in proton-proton collisions at RHIC. Sensitivity of this measurement
to the polarization of down-type antiquarks is demonstrated.


title:
Detection of a Temperature Inversion in the Broadband Infrared Emission
  Spectrum of TrES-4

abstract:
  We estimate the strength of the bandpass-integrated thermal emission from the
extrasolar planet TrES-4 at 3.6, 4.5, 5.8, and 8.0 micron using the Infrared
Array Camera (IRAC) on the Spitzer Space Telescope. We find relative eclipse
depths of 0.137 +/- 0.011%, 0.148 +/- 0.016%, 0.261 +/- 0.059%, and 0.318 +/-
0.044% in these four bandpasses, respectively. We also place a 2 sigma upper
limit of 0.37% on the depth of the secondary eclipse in the 16 micron IRS
peak-up array. These eclipse depths reveal that TrES-4 has an emission spectrum
similar to that of HD 209458b, which requires the presence of water emission
bands created by an thermal inversion layer high in the atmosphere in order to
explain the observed features. TrES-4 receives more radiation from its star
than HD 209458b and has a correspondingly higher effective temperature,
therefore the presence of a temperature inversion in this planet's atmosphere
lends support to the idea that inversions might be correlated with the
irradiance received by the planet. We find no evidence for any offset in the
timing of the secondary eclipse, and place a 3 sigma upper limit of
|ecos(omega)|<0.0058 where e is the planet's orbital eccentricity and omega is
the argument of pericenter. From this we conclude that tidal heating from
ongoing orbital circulatization is unlikely to be the explanation for TrES-4's
inflated radius.


title:
Exact stochastic Liouville and Schr\"{o}dinger equations for open
  systems

abstract:
  An universal form of kinetic equation for open systems is considered which
naturally unifies classical and quantum cases and allows to extend concept of
wave function to open quantum systems. Corresponding stochastic Schr\"{o}dinger
equation is derived and illustrated by the example of inelastic scattering in
quantum conduction channel.


title:
An example of a Teichmuller disk in genus 4 with degenerate
  Kontsevich-Zorich spectrum

abstract:
  We construct an orientable holomorphic quadratic differential on a Riemann
surface of genus 4 whose SL(2,R)-orbit is closed and has a highly degenerate
Kontsevich - Zorich spectrum. This example is related to a previous similar
construction in genus 3 by the first author.


title:
The formation of compact massive self-gravitating discs in metal-free
  haloes with virial temperatures of ~ 13000-30000 K

abstract:
  We have used the hydrodynamical AMR code ENZO to investigate the dynamical
evolution of the gas at the centre of dark matter haloes with virial velocities
of ~ 20 - 30 kms and virial temperatures of ~ 13000-30000 K at z ~ 15 in a
cosmological context. The virial temperature of the dark matter haloes is above
the threshold where atomic cooling by hydrogen allows the gas to cool and
collapse. We neglect cooling by molecular hydrogen and metals, as may be
plausible if H_2 cooling is suppressed by a meta-galactic Lyman-Werner
background or an internal source of Lyman-Werner photons, and metal enrichment
has not progressed very far. The gas in the haloes becomes gravitationally
unstable and develops turbulent velocities comparable to the virial velocities
of the dark matter haloes. Within a few dynamical times it settles into a
nearly isothermal density profile over many decades in radius losing most of
its angular momentum in the process. About 0.1 - 1 % of the baryons, at the
centre of the dark matter haloes, collapse into a self-gravitating, fat,
ellipsoidal, centrifugally supported exponential disc with scale-length of ~
0.075-0.27 pc and rotation velocities of 25-60 kms. We are able to follow the
settling of the gas into centrifugal support and the dynamical evolution of the
compact disc in each dark matter halo for a few dynamical times. The dynamical
evolution of the gas at the centre of the haloes is complex. In one of the
haloes the gas at the centre fragments into a triple system leading to strong
tidal perturbations and eventually to the in-fall of a secondary smaller clump
into the most massive primary clump. The formation of centrifugally supported
self-gravitating massive discs is likely to be an important intermediary stage
en route to the formation of a massive black hole seed.


title:
Instabilities of naked singularities and black hole interiors in General
  Relativity

abstract:
  Metrics representing black holes in General Relativity may exhibit naked
singularities for certain values of their parameters. This is the case for
super-extremal ($J^2 > M>0$) Kerr and super-extremal ($|Q|>M>0$)
Reissner-N\"ordstrom spacetimes, and also for the negative mass Schwarzschild
spacetime. We review our recent work where we show that these nakedly singular
spacetimes are unstable under linear gravitational perturbations, a result that
supports the cosmic censorship conjecture, and also that the inner stationary
region beyond the inner horizon of a Kerr black hole ($J^2 <M$) is linearly
unstable.


title: Entanglement Theory and the Quantum Simulation of Many-Body Physics

abstract:
  In this thesis we present new results relevant to two important problems in
quantum information science: the development of a theory of entanglement and
the exploration of the use of controlled quantum systems to the simulation of
quantum many-body phenomena.
  In the first part we introduce a new approach to the study of entanglement by
considering its manipulation under operations not capable of generating
entanglement and show there is a total order for multipartite quantum states in
this framework. We also present new results on hypothesis testing of correlated
sources and give further evidence on the existence of NPPT bound entanglement.
  In the second part, we study the potential as well as the limitations of a
quantum computer for calculating properties of many-body systems. First we
analyse the usefulness of quantum computation to calculate additive
approximations to partition functions and spectral densities of local
Hamiltonians. We then show that the determination of ground state energies of
local Hamiltonians with an inverse polynomial spectral gap is QCMA-hard.
  In the third and last part, we approach the problem of quantum simulating
many-body systems from a more pragmatic point of view. We analyze the
realization of paradigmatic condensed matter Hamiltonians in arrays of coupled
microcavities, such as the Bose-Hubbard and the anisotropic Heisenberg models,
and discuss the feasibility of an experimental realization with
state-of-the-art current technology.


title:
Telescope Optics and Weak Lensing: PSF Patterns due to Low Order
  Aberrations

abstract:
  In weak lensing investigations, galaxy shapes are deconvolved for the effects
of the point spread function (PSF) using stellar images. In this paper we use
physical models of the telescope optics to understand the spatial variation of
the PSF in the image plane. We introduce a set of parameters to model the key
aberrations, which include defocus, focal plane tilt, primary and off-axis
astigmatism. We also include the effects of guiding and seeing. We test our
model with data from the Blanco 4 meter telescope in Cerro Tololo, Chile. We
find that the physical model describes a substantial part of the PSF size and
anisotropy over the field of view (over 90 percent of it, based on a
chi-squared metric). We identify the primary contributors to the PSF patterns
and study their covariances and principal components. We also identify
correlations with the effect of gravity on the telescope. Finally, we discuss
the improvements in PSF estimation that may be achieved by combining the
physical model in this study with the purely empirical approach of Jarvis and
Jain (2004).


title: Coulomb Phase Gluon Scattering at Strong Coupling

abstract:
  We calculate corrections to gluon scattering amplitudes in a Coulomb phase
using gauge/string duality. The Coulomb phase considered is a maximal rank
breaking of $SU(n_1+n_2)\to SU(n_1)\times SU(n_2) \times U(1)$. This problem
therefore has 3 scales involved: 1) the scale of the massive fields $M_W$
arising from the spontaneous breaking of the gauge group; 2) The scale of the
scattering, characterized by the Mandelstam variables $s,t,u$; 3) The IR
regulator $m_{IR}$. We find corrections in the hard scattering limit $
|s|,|t|,|u|\gg m_{IR}^2 \gg M_W^2$, and also find below threshold corrections
with $M_W^2 \gg |s|,|t|,|u|$. We find that the corrections in the second case
are finite, and so are IR regulator independent.


title: Topological Effects of Synaptic Time Dependent Plasticity

abstract:
  We show that the local Spike Timing-Dependent Plasticity (STDP) rule has the
effect of regulating the trans-synaptic weights of loops of any length within a
simulated network of neurons. We show that depending on STDP's polarity,
functional loops are formed or eliminated in networks driven to normal spiking
conditions by random, partially correlated inputs, where functional loops
comprise weights that exceed a non-zero threshold. We further prove that STDP
is a form of loop-regulating plasticity for the case of a linear network
comprising random weights drawn from certain distributions. Thus a notable
local synaptic learning rule makes a specific prediction about synapses in the
brain in which standard STDP is present: that under normal spiking conditions,
they should participate in predominantly feed-forward connections at all
scales. Our model implies that any deviations from this prediction would
require a substantial modification to the hypothesized role for standard STDP.
Given its widespread occurrence in the brain, we predict that STDP could also
regulate long range synaptic loops among individual neurons across all brain
scales, up to, and including, the scale of global brain network topology.

categories: q-bio.NC cond-mat.dis-nn math-ph math.MP q-bio.TO


title: Deformations of algebroid stacks

abstract:
  In this paper we consider deformations of an algebroid stack on an etale
groupoid. We construct a differential graded Lie algebra (DGLA) which controls
this deformation theory. In the case when the algebroid is a twisted form of
functions we show that this DGLA is quasiisomorphic to the twist of the DGLA of
Hochschild cochains on the algebra of functions on the groupoid by the
characteristic class of the corresponding gerbe.


title:
The effect of progenitor age and metallicity on luminosity and 56Ni
  yield in Type Ia supernovae

abstract:
  Timmes, Brown & Truran found that metallicity variations could theoretically
account for a 25% variation in the mass of 56Ni synthesized in Type Ia
supernovae (SNe Ia), and thus account for a large fraction of the scatter in
observed SN Ia luminosities. Higher-metallicity progenitors are more
neutron-rich, producing more stable burning products relative to radioactive
56Ni. We develop a new method for estimating bolometric luminosity and 56Ni
yield in SNe Ia and use it to test the theory with data from the Supernova
Legacy Survey. We find that the average 56Ni yield does drop in SNe Ia from
high metallicity environments, but the theory can only account for 7%--10% of
the dispersion in SN Ia 56Ni mass, and thus luminosity. This is because the
effect is dominant at metallicities significantly above solar, whereas we find
that SN hosts have predominantly subsolar or only moderately above-solar
metallicities. We also show that allowing for changes in O/Fe with the
metallicity [Fe/H] does not have a major effect on the theoretical prediction
of Timmes, Brown & Truran, so long as one is using the O/H as the independent
variable. Age may have a greater effect than metallicity -- we find that the
luminosity weighted age of the host galaxy is correlated with 56Ni yield, and
thus more massive progenitors give rise to more luminous explosions. This is
hard to understand if most SNe Ia explode when the primaries reach the
Chandrasekhar mass. Finally, we test the findings of Gallagher et al., that the
residuals of SNe Ia from the Hubble diagram are correlated with host galaxy
metallicity, and we find no such correlation.


title:
Fusion subcategories of representation categories of twisted quantum
  doubles of finite groups

abstract:
  We describe all fusion subcategories of the representation category of a
twisted quantum double of a finite group. In view of the fact that every
group-theoretical braided fusion category can be embedded into a representation
category of a twisted quantum double of a finite group, this gives a complete
description of all group-theoretical braided fusion categories. We describe the
lattice and give formulas for some invariants of the fusion subcategories of
representation category of a twisted quantum double of a finite group. We also
give a characterization of group-theoretical braided fusion categories as
equivariantizations of pointed categories.


title: Complexity Classes as Mathematical Axioms

abstract:
  Treating a conjecture, P^#P != NP, on the separation of complexity classes as
an axiom, an implication is found in three manifold topology with little
obvious connection to complexity theory. This is reminiscent of Harvey
Friedman's work on finitistic interpretations of large cardinal axioms.


title: Supersymmetric Higgs singlet effects on FCNC observables

abstract:
  Higgs singlet superfields, usually present in extensions of the Minimal
Supersymmetric Standard Model (MSSM) which address the $\mu$-problem, such as
the Next-to-Minimal Supersymmetric Standard Model (NMSSM) and the Minimal
Nonminimal Supersymmetric Standard Model (mnSSM), can have significant
contributions to $B$-meson flavour-changing neutral current observables for
large values of $\tan\beta \gsim 50$. Illustrative results are presented
including effects on the $B_s$ and on the rare decay $B_s\to\mu^+\mu^-$. In
particular, we find that in the NMSSM, the branching ratio for
$B_s\to\mu^+\mu^-$ can be enhanced or even suppressed with respect to the
Standard Model prediction by more than one order of magnitude.


title:
Non-thermal radiation from molecular clouds illuminated by cosmic rays
  from nearby supernova remnants

abstract:
  Molecular clouds are expected to emit non-thermal radiation due to cosmic ray
interactions in the dense magnetized gas. Such emission is amplified if a cloud
is located close to an accelerator of cosmic rays and if cosmic rays can leave
the accelerator and diffusively reach the cloud. We consider the situation in
which a molecular cloud is located in the proximity of a supernova remnant
which is accelerating cosmic rays and gradually releasing them into the
interstellar medium. We calculate the multiwavelength spectrum from radio to
gamma rays which emerges from the cloud as the result of cosmic ray
interactions. The total energy output is dominated by the gamma ray emission,
which can exceed the emission from other bands by an order of magnitude or
more. This suggests that some of the unidentified TeV sources detected so far,
with no obvious or very weak counterpart in other wavelengths, might be
associated with clouds illuminated by cosmic rays coming from a nearby source.


title:
Spectroscopic Confirmation of a Massive Red-Sequence-Selected Galaxy
  Cluster at z = 1.34 in the SpARCS-South Cluster Survey

abstract:
  The Spitzer Adaptation of the Red-sequence Cluster Survey (SpARCS) is a
z'-passband imaging survey, consisting of deep (z' ~ 24 AB) observations made
from both hemispheres using the CFHT 3.6m and CTIO 4m telescopes. The survey
was designed with the primary aim of detecting galaxy clusters at z >~ 1. In
tandem with pre-existing 3.6um observations from the Spitzer Space Telescope
SWIRE Legacy Survey, SpARCS detects clusters using an infrared adaptation of
the two-filter red-sequence cluster technique. The total effective area of the
SpARCS cluster survey is 41.9 deg^2. In this paper, we provide an overview of
the 13.6 deg^2 Southern CTIO/MOSAICII observations. The 28.3 deg^2 Northern
CFHT/MegaCam observations are summarized in a companion paper by Muzzin et al.
(2008). In this paper, we also report spectroscopic confirmation of SpARCS
J003550-431224, a very rich galaxy cluster at z = 1.335, discovered in the
ELAIS-S1 field. To date, this is the highest spectroscopically confirmed
redshift for a galaxy cluster discovered using the red-sequence technique.
Based on nine confirmed members, SpARCS J003550-431224 has a preliminary
velocity dispersion of 1050 +/- 230 km/s. With its proven capability for
efficient cluster detection, SpARCS is a demonstration that we have entered an
era of large, homogeneously-selected z > 1 cluster surveys.


title:
Measurement of the angular and lifetime parameters of the decays
  $B_{d}^{0}\to J/\psi K^{*0}$ and $B_{s}^{0}\to J/\psi\phi$

abstract:
  We present measurements of the linear polarization amplitudes and the strong
relative phases that describe the flavor-untagged decays $B_{d}^{0}\to J/\psi
K^{*0}$ and $B_{s}^{0}\to J/\psi\phi$ in the transversity basis. We also
measure the mean lifetime $\bar{\tau}_{s}$ of the $B_{s}^{0}$ mass eigenstates
and the lifetime ratio $\bar{\tau}_{s}/\tau_{d}$. The analyses are based on
approximately 2.8 fb$^{-1}$ of data recorded with the D0 detector. From our
measurements of the angular parameters we conclude that there is no evidence
for a deviation from flavor SU(3) symmetry for these decays and that the
factorization assumption is not valid for the $B_{d}^{0}\to J/\psi K^{*0}$
decay.


title: Regular and Biregular module algebras

abstract:
  Motivated by the study of von Neumann regular skew groups as carried out by
Alfaro, Ara and del Rio in 1995 we investigate regular and biregular Hopf
module algebras. If $A$ is an algebra with an action by an affine Hopf algebra
$H$, then any $H$-stable left ideal of $A$ is a direct summand if and only if
$A^H$ is regular and the invariance functor $(-)^H$ induces an equivalence of
$A^H$-Mod to the Wisbauer category of $A$ as $A# H$-module. Analogously we show
a similar statement for the biregularity of $A$ relative to $H$ where $A^H$ is
replaced by $R=Z(A)\cap A^H$ using the module theory of $A$ as a module over
$A\otimes A^{op} \bowtie H$ the envelopping Hopf algebroid of $A$ and $H$. We
show that every two-sided $H$-stable ideal of $A$ is generated by a central
$H$-invariant idempotent if and only if $R$ is regular and $A_m$ is $H$-simple
for all maximal ideals $m$ of $R$. Further sufficient conditions are given for
$A# H$ and $A^H$ to be regular.


title: Halo Mass Functions in Early Dark Energy Cosmologies

abstract:
  We examine the linear density contrast at collapse time, $\delta_c$ for
large-scale structure in dynamical dark energy cosmologies, including models
with early dark energy. Contrary to previous results, we find that as long as
dark energy is homogeneous on small scales, $\delta_c$ is insensitive to dark
energy properties for parameter values fitting current data, including the case
of early dark energy. This is significant since using the correct $\delta_c$ is
crucial for accurate Press-Schechter prediction of the halo mass function.
Previous results have found an apparent failing of the extended Press-Schechter
approach (Sheth-Tormen) for early dark energy. Our calculations demonstrate
that with the correct $\delta_c$ the accuracy of this approach is restored. We
discuss the significance of this result for the halo mass function and examine
what dark energy physics would be needed to cause significant change in
$\delta_c$, and the observational signatures this would leave.


title:
Bottom spectroscopy on dynamical 2+1 flavor domain wall fermion lattices
  with a relativistic heavy quark action

abstract:
  Following the successful application of the relativistic heavy quark(RHQ)
action to the charmonium and charm-strange meson spectrum, we study here the
bottom system to explore the validity of this method in a regime with larger
heavy quark momenta. The spectrum is calculated using the same dynamical 2+1
flavor, $24^3\times 64$ domain wall fermion lattice configurations generated by
the RBC and UKQCD collaborations and used in the earlier charm study. The 3
parameters in the RHQ action are determined by matching to the experimental
bottom-strange meson masses and extrapolated to the chiral limit from three
different sea quark masses. We predict the bottomonium mass spectrum and
compare it with experiment. A theoretical estimation is also carried out to
understand the $O(a^2p^2)$ systematic errors found in the numerical study.


title: When $\delta$-semiperfect rings are semiperfect

abstract:
  Zhou defined $\delta$-semiperfect rings as a proper generalization of
semiperfect rings. The purpose of this paper is to discuss relative notions of
supplemented modules and to show that the semiperfect rings are precisely the
semilocal rings which are $\delta$-supplemented. Module theoretic version of
our results are obtained.


title: Critical Points in the Linear Sigma Model with Quarks

abstract:
  We employ a simple effective model to study the chiral dynamics of two
flavors of quarks at finite temperature and density. In particular, we
determine the phase diagram in the plane of temperature and baryon chemical
potential as a function of the pion mass. An interesting phase structure occurs
which results in zero, one or two critical points depending on the value of the
vacuum pion mass.


title: The automorphism group of accessible groups

abstract:
  In this article, we study the outer automorphism group of a group G
decomposed as a finite graph of group with finite edge groups and finitely
generated vertex groups with at most one end. We show that Out(G) is
essentially obtained by taking extensions of relative automorphism groups of
vertex groups, groups of Dehn twists and groups of automorphisms of free
products. We apply this description and obtain a criterion for Out(G) to be
finitely presented, as well as a necessary and sufficient condition for Out(G)
to be finite. Consequences for hyperbolic groups are discussed.


title: Hyper-gratings: nanophotonics in planar anisotropic metamaterials

abstract:
  We present a technique capable of producing subwavelength focal spots in the
far-field of the source in planar non-resonant structures. The approach
combines the diffraction gratings that generate the high-wavevector-number
modes and planar slabs of homogeneous anisotropic metamaterials that propagate
these waves and combine them at the subwavelength focal spots. In a sense, the
technique combines the benefits of Fresnel lens, near-field zone plates,
hyperlens, and superlens, and at the same time resolves their fundamental
limitations. Several realizations of the proposed technique for visible,
near-IR, and mid-IR frequencies are proposed, and their performance is analyzed
theoretically and numerically. Generalization of the developed approach for
sub-diffractional on-chip photonics is suggested.


title:
Nucleon structure with dynamical (2+1)-flavor domain wall fermions
  lattice QCD

abstract:
  We report isovector form factors and low moments of isovector structure
functions of nucleon from the coarse RIKEN-BNL-Columbia (RBC) and UKQCD joint
dynamical (2+1)-flavor domain-wall fermions (DWF) ensembles. The lattice cut
off is estimated at (a^{-1}=1.7) GeV. The lattice volume is as large as 2.7 fm
across. We carefully optimize the nucleon source/sink separation in time to
about 1.4 fm. Unexpectedly large finite-size effect in the axial charge is
found. The effect scales with a single variable, the product (m_\pi L) of the
pion mass (m_\pi) and lattice spatial linear extent (L), and sets in at around
(m_\pi L = 5). We also discuss momentum-transfer dependence of the vector,
induced tensor, axial-vector and induced pesudo-scalar form factors.
  From structure functions, fully non-perturbatively renormalized iso-vector
quark momentum fraction, (< x >_{u-d}), helicity fraction, (< x >_{\Delta u -
\Delta d}), and transversity, (< 1 >_{\delta u - \delta d}), are reported, as
well as an unrenormalized twist-3 coefficient, (d_1). The ratio of the momentum
to helicity fractions, (< x >_{u-d}/< x >_{\Delta u - \Delta d}), does not
depend on light quark mass and agree well with the experiment. Their respective
absolute values, fully renormalized, shows interesting trending toward the
respective experimental values at the lightest light quark mass.


title: Estimating Speed and Damping in the Stochastic Wave Equation

abstract:
  A parameter estimation problem is considered for a one-dimensional stochastic
wave equation driven by additive space-time Gaussian white noise.
  The estimator is of spectral type and utilizes a finite number of the spatial
Fourier coefficients of the solution. The asymptotic properties of the
estimator are studied as the number of the Fourier coefficients increases,
while the observation time and the noise intensity are fixed.


title:
Reducing the Bias and Uncertainty of Free Energy Estimates by Using
  Regression to Fit Thermodynamic Integration Data

abstract:
  This report presents the application of polynomial regression for estimating
free energy differences using thermodynamic integration. We employ linear
regression to construct a polynomial that optimally fits the thermodynamic
integration data, and thus reduces the bias and uncertainty of the resulting
free energy estimate. Two test systems with analytical solutions were used to
verify the accuracy and precision of the approach. Our results suggest that
regression with a high degree of polynomials give the most accurate free energy
difference estimates, but often with a slightly larger variance, compared to
commonly used quadrature techniques. High degrees of polynomials possess the
flexibility to closely fit the thermodynamic integration data but are often
sensitive to small changes in data points. To further improve overall accuracy
and reduce uncertainty, we also examine the use of Chebyshev nodes to guide the
selection of non-equidistant lambda values for the thermodynamic integration
scheme. We conclude that polynomial regression with non-equidistant lambda
values delivers the most accurate and precise free energy estimates for
thermodynamic integration data. Software and documentation is available at
http://www.phys.uidaho.edu/ytreberg/software


title: Large HI structures linked to southern O-type stars

abstract:
  In our search for interstellar bubbles around massive stars we analyze the
environs of the O-type stars HD 38666, HD 124979, HD 163758, and HD 171589. The
location of the stars, which are placed far from the galactic plane, favors the
formation of large wind bubbles. We investigate the distribution of the neutral
and ionized gas based on HI, CO, and radio continuum data, and that of the
interstellar dust based on far infrared IRIS images. Here we report the
discovery of neutral gas cavities and slowly expanding shells associated with
the four massive stars. IR and optical counterparts were also detected for some
of the stars. We discuss the probability that the features have originated in
the action of the stellar winds on the surrounding gas.


title:
A comparative study of CO adsorption on flat, stepped and kinked Au
  surfaces using density functional theory

abstract:
  Our ab initio calculations of CO adsorption energies on low miller index
(111), (100), stepped (211), and kinked (532) gold surfaces show a strong
dependence on local coordination with a reduction in Au atom coordination
leading to higher binding energies. We find trends in adsorption energies to be
similar to those reported in experiments and calculations for other metal
surfaces. The (532) surface provides insights into these trends because of the
availability of a large number of kink sites which naturally have the lowest
coordination (6). We also find that, for all surfaces, an increase in CO
coverage triggers a decrease in the adsorption energy. Changes in the
work-function upon CO adsorption, as well as the frequencies of the CO
vibrational modes are calculated, and their coverage dependence is reported.


title:
Optical probe of carrier doping by X-ray irradiation in organic dimer
  Mott insulator $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}]$Cl

abstract:
  We investigated the infrared optical spectra of an organic dimer Mott
insulator $\kappa$-(BEDT-TTF)$_{2}$Cu[N(CN)$_{2}$]Cl, which was irradiated with
X-rays. We observed that the irradiation caused a large spectral weight
transfer from the mid-infrared region, where interband transitions in the dimer
and Mott-Hubbard bands take place, to a Drude part in a low-energy region; this
caused the Mott gap to collapse. The increase of the Drude part indicates a
carrier doping into the Mott insulator due to irradiation defects. The strong
redistribution of the spectral weight demonstrates that the organic Mott
insulator is very close to the phase border of the bandwidth-controlled Mott
transition.


title: How to Make Sense of the Jet Correlations Results at RHIC?

abstract:
  We review the di-hadron correlation results from RHIC. A consistent physical
picture was constructed based on the correlation landscape in $p_T$,
$\Delta\phi$, $\Delta\eta$ and particle species. We show that the data are
consistent with competition between fragmentation of survived jets and response
of the medium to quenched jets. At intermediate $p_T$ where the medium response
are important, a large fraction of trigger hadrons do not come from jet
fragmentation. We argue that these hadrons can strongly influence the
interpretation of the low $p_T$ correlation data. We demonstrate this point
through a simple geometrical jet absorption model simulation. The model shows
that the correlation between medium response hadrons dominates the pair yield
and mimics the double hump structure of the away-side $\Delta\phi$ distribution
at low $p_T$. This correlation was also shown to lead to complications in
interpreting the results on reaction plane dependence and three particle
correlations. Finally, we briefly discuss several experimental issues which are
important for proper interpretations of the experimental data.


title: Planar Visibility Counting

abstract:
  For a fixed virtual scene (=collection of simplices) S and given observer
position p, how many elements of S are weakly visible (i.e. not fully occluded
by others) from p? The present work explores the trade-off between query time
and preprocessing space for these quantities in 2D: exactly, in the approximate
deterministic, and in the probabilistic sense. We deduce the EXISTENCE of an
O(m^2/n^2) space data structure for S that, given p and time O(log n), allows
to approximate the ratio of occluded segments up to arbitrary constant absolute
error; here m denotes the size of the Visibility Graph--which may be quadratic,
but typically is just linear in the size n of the scene S. On the other hand,
we present a data structure CONSTRUCTIBLE in O(n*log(n)+m^2*polylog(n)/k)
preprocessing time and space with similar approximation properties and query
time O(k*polylog n), where k<n is an arbitrary parameter. We describe an
implementation of this approach and demonstrate the practical benefit of the
parameter k to trade memory for query time in an empirical evaluation on three
classes of benchmark scenes.


title: Life at the front of an expanding population

abstract:
  Recent microbial experiments suggest that enhanced genetic drift at the
frontier of a two-dimensional range expansion can cause genetic sectoring
patterns with fractal domain boundaries. Here, we propose and analyze a simple
model of asexual biological evolution at expanding frontiers to explain these
neutral patterns and predict the effect of natural selection. Our model
attributes the observed gradual decrease in the number of sectors at the
leading edge to an unbiased random walk of sector boundaries. Natural selection
introduces a deterministic bias in the wandering of domain boundaries that
renders beneficial mutations more likely to escape genetic drift and become
established in a sector. We find that the opening angle of those sectors and
the rate at which they become established depend sensitively on the selective
advantage of the mutants. Deleterious mutations, on the other hand, are not
able to establish a sector permanently. They can, however, temporarily "surf"
on the population front, and thereby reach unusual high frequencies. As a
consequence, expanding frontiers are susceptible to deleterious mutations as
revealed by the high fraction of mutants at mutation-selection balance.
Numerically, we also determine the condition at which the wild type is lost in
favor of deleterious mutants (genetic meltdown) at a growing front. Our
prediction for this error threshold differs qualitatively from existing
well-mixed theories, and sets tight constraints on sustainable mutation rates
for populations that undergo frequent range expansions.


title: Automorphism groups of N=2 superconformal super-Riemann spheres

abstract:
  In previous work, the author proved that there is a countably infinite family
of N=2 superconformal equivalence classes of DeWitt N=2 superconformal
super-Riemann surfaces with closed, genus-zero body. In this paper, we
determine the automorphism groups for these N=2 superconformal super-Riemann
surfaces, and analyze the Lie structure of these groups. Under the
correspondence between N=2 superconformal and N=1 superanalytic structures, the
results extend to the determination of automorphism groups of N=1 superanalytic
DeWitt super-Riemann surfaces with closed, genus-zero body.


title:
Comparisons for backward stochastic differential equations on Markov
  chains and related no-arbitrage conditions

abstract:
  Most previous contributions to BSDEs, and the related theories of nonlinear
expectation and dynamic risk measures, have been in the framework of continuous
time diffusions or jump diffusions. Using solutions of BSDEs on spaces related
to finite state, continuous time Markov chains, we develop a theory of
nonlinear expectations in the spirit of [Dynamically consistent nonlinear
evaluations and expectations (2005) Shandong Univ.]. We prove basic properties
of these expectations and show their applications to dynamic risk measures on
such spaces. In particular, we prove comparison theorems for scalar and vector
valued solutions to BSDEs, and discuss arbitrage and risk measures in the
scalar case.


title: Superconductivity in heavily boron-doped silicon carbide

abstract:
  The discoveries of superconductivity in heavily boron-doped diamond (C:B) in
2004 and silicon (Si:B) in 2006 renew the interest in the superconducting state
of semiconductors. Charge-carrier doping of wide-gap semiconductors leads to a
metallic phase from which upon further doping superconductivity can emerge.
Recently, we discovered superconductivity in a closely related system:
heavily-boron doped silicon carbide (SiC:B). The sample used for that study
consists of cubic and hexagonal SiC phase fractions and hence this lead to the
question which of them participates in the superconductivity. Here we focus on
a sample which mainly consists of hexagonal SiC without any indication for the
cubic modification by means of x-ray diffraction, resistivity, and ac
susceptibility.