title: Barrier crossing to the small Holstein polaron regime

abstract:
  We investigate the dimensionality effects of the Holstein polaron from the
fully quantum regime, where the crossover between large and small polaron
solutions is known to be continuous in all dimensions, into the limit described
by the semiclassical Discrete Nonlinear Schr\"odinger (DNLS) Equation, where
the crossover is continuous in 1D but discontinuous in higher dimensions. We
use exact numerics on one hand and a two variable parametrization of the
Toyozawa ansatz on the other in order to probe the crossover region in all
parameter regimes. We find that a barrier appears also in 1D separating the two
types of solutions, seemingly in contradiction to the common paradigm for the
DNLS according to which the crossover is barrier-free. We quantify the polaron
behavior in the crossover region as a function of the exciton overlap and find
that the barrier remains small in 1D and tunnelling through it is not
rate-limiting.


title:
First Direct Bound on the Total Width of the Top Quark in ppbar
  Collisions at sqrt(s) = 1.96 TeV

abstract:
  We present the first direct experimental bound on the total decay width of
the top quark using 955pb^-1 of the Tevatron's ppbar collisions recorded by the
Collider Detector at Fermilab. We identify 253 top-antitop pair candidate
events. The distribution of reconstructed top quark mass from these events is
fitted to templates representing different values of the top quark width. Using
a confidence interval based on likelihood ratio ordering, we extract an upper
limit at 95% C.L. of Gamma_t <13.1 GeV for an assumed top quark mass of 175
GeV/c^2.


title:
Interstellar Weather Vanes: GLIMPSE Mid-Infrared Stellar-Wind Bowshocks
  in M17 and RCW49

abstract:
  We report the discovery of six infrared stellar-wind bowshocks in the
Galactic massive star formation regions M17 and RCW49 from Spitzer GLIMPSE
(Galactic Legacy Infrared Mid-Plane Survey Extraordinaire) images. The InfraRed
Array Camera (IRAC) on the Spitzer Space Telescope clearly resolves the
arc-shaped emission produced by the bowshocks. We combine Two Micron All-Sky
Survey (2MASS), Spitzer, MSX, and IRAS observations to obtain the spectral
energy distributions (SEDs) of the bowshocks and their individual driving
stars. We use the stellar SEDs to estimate the spectral types of the three
newly-identified O stars in RCW49 and one previously undiscovered O star in
M17. One of the bowshocks in RCW49 reveals the presence of a large-scale flow
of gas escaping the H II region at a few 10^2 km/s. Radiation-transfer modeling
of the steep rise in the SED of this bowshock toward longer mid-infrared
wavelengths indicates that the emission is coming principally from dust heated
by the star driving the shock. The other 5 bowshocks occur where the stellar
winds of O stars sweep up dust in the expanding H II regions.


title:
\'Etale cohomology, Lefschetz Theorems and Number of Points of Singular
  Varieties over Finite Fields

abstract:
  We prove a general inequality for estimating the number of points of
arbitrary complete intersections over a finite field. This extends a result of
Deligne for nonsingular complete intersections. For normal complete
intersections, this inequality generalizes also the classical Lang-Weil
inequality. Moreover, we prove the Lang-Weil inequality for affine as well as
projective varieties with an explicit description and a bound for the constant
appearing therein. We also prove a conjecture of Lang and Weil concerning the
Picard varieties and \'etale cohomology spaces of projective varieties. The
general inequality for complete intersections may be viewed as a more precise
version of the estimates given by Hooley and Katz. The proof is primarily based
on a suitable generalization of the Weak Lefschetz Theorem to singular
varieties together with some Bertini-type arguments and the
Grothendieck-Lefschetz Trace Formula. We also describe some auxiliary results
concerning the \'etale cohomology spaces and Betti numbers of projective
varieties over finite fields and a conjecture along with some partial results
concerning the number of points of projective algebraic sets over finite
fields.


title:
Theory of possible effects of the Allee phenomenon on refugia of the
  Hantavirus epidemic

abstract:
  We investigate possible effects of high order nonlinearities on the shapes of
infection refugia of the Hantavirus epidemic. We replace Fisher-like equations
that have been recently used to describe Hantavirus spread in mouse populations
by generalizations capable of describing Allee effects that are a consequence
of the high order nonlinearities. We analyze the equations to calculate steady
state solutions. We study the stability of those solutions under physical
conditions and compare to the earlier Fisher-like case. We consider spatial
modulation of the environment and find that unexpected results appear,
including a bifurcation that has not been studied before.


title: Magneto-Optical Trap for Polar Molecules

abstract:
  We propose a method for laser cooling and trapping a substantial class of
polar molecules, and in particular titanium (II) oxide (TiO). This method uses
pulsed electric fields to nonadiabatically remix the ground-state magnetic
sublevels of the molecule, allowing us to build a magneto-optical trap (MOT)
based on a quasi-cycling $J'=J"-1$ transition. Monte-Carlo simulations of this
electrostatically remixed MOT (ER-MOT) demonstrate the feasibility of cooling
TiO to a temperature of 10 $\mathrm{\mu}K$ and trapping it with a
radiation-pumping-limited lifetime on the order of 80 ms.


title: The Continuous Graph FFT

abstract:
  The discrete Fourier transform and the FFT algorithm are extended from the
circle to continuous graphs with equal edge lengths.


title: The local recognition of reflection graphs of spherical Coxeter groups

abstract:
  Based on the third author's thesis in this article we complete the local
recognition of commuting reflection graphs of spherical Coxeter groups arising
from irreducible crystallographic root systems.


title: Group Averaging of massless scalar fields in 1+1 de Sitter

abstract:
  Perturbative gravity in global de Sitter space is subject to so-called
linearization stability constraints: If they are to couple consistently to the
gravitational field, quantum states must be invariant under the de Sitter
isometries. While standard Fock spaces contain no de Sitter-invariant states
apart from (possibly) the vacuum, a full Hilbert space of de Sitter-invariant
quantum states can be constructed via group averaging techiniques. We
re-examine the simple toy model of de Sitter group averaging given by the free
1+1 scalar field, expanding on an earlier analysis by Higuchi. Our purpose is
twofold: to include the scalar zero-mode, and to explicitly count the number of
de Sitter-invariant states as a function of an appropriately defined energy.


title:
Study of singular radius and surface boundary constraints in refractive
  beam shaper design

abstract:
  This paper presents analysis of important issues associated with the design
of refractive laser beam shaping systems. The concept of singular radius is
introduced along with solutions to minimize its adverse effect on shaper
performance. In addition, the surface boundary constraint is discussed in
detail. This study provides useful guidelines to circumvent possible design
errors that would degrade the shaper quality or add undesired complication to
the system.


title: Resonance parameters from K-matrix and T-matrix poles

abstract:
  We extract K-matrix poles from our fits to elastic pion-nucleon scattering
and eta-nucleon production data in order to test a recently proposed method for
the determination of resonance properties, based on the trace of the K-matrix.
We have considered issues associated with the separation of background and
resonance contributions, the correspondence between K-matrix and T-matrix
poles, and the complicated behavior of eigenphases.


title: Symmetries and modelling functions for diffusion processes

abstract:
  A constructive approach to theory of diffusion processes is proposed, which
is based on application of both the symmetry analysis and method of modelling
functions. An algorithm for construction of the modelling functions is
suggested. This algorithm is based on the error functions expansion (ERFEX) of
experimental concentration profiles. The high-accuracy analytical description
of the profiles provided by ERFEX approximation allows a convenient extraction
of the concentration dependence of diffusivity from experimental data and
prediction of the diffusion process. Our analysis is exemplified by its
employment to experimental results obtained for surface diffusion of lithium on
the molybdenum (112) surface pre-covered with dysprosium. The ERFEX
approximation can be directly extended to many other diffusion systems.


title: Local Causality and Completeness: Bell vs. Jarrett

abstract:
  J.S. Bell believed that his famous theorem entailed a deep and troubling
conflict between the empirically verified predictions of quantum theory and the
notion of local causality that is motivated by relativity theory. Yet many
physicists continue to accept, usually on the reports of textbook writers and
other commentators, that Bell's own view was wrong, and that, in fact, the
theorem only brings out a conflict with determinism or the hidden-variables
program or realism or some other such principle that (unlike local causality),
allegedly, nobody should have believed anyway. (Moreover, typically such
beliefs arise without the person in question even being aware that the view
they are accepting differs so radically from Bell's own.) Here we try to shed
some light on the situation by focusing on the concept of local causality that
is the heart of Bell's theorem, and, in particular, by contrasting Bell's own
understanding with the analysis of Jon Jarrett which has been the most
influential source, in recent decades, for the kinds of claims mentioned
previously. We point out a crucial difference between Jarrett's and Bell's own
understanding of Bell's formulation of local causality, which turns out to be
the basis for the erroneous claim, made by Jarrett and many others, that Bell
misunderstood the implications of his own theorem.


title: Magnetic Reconnection by a Self-Retreating X-Line

abstract:
  Particle-in-cell (PIC) simulations of collisionless magnetic reconnection are
performed to study asymmetric reconnection in which an outflow is blocked by a
hard wall while leaving sufficiently large room for the outflow of the opposite
direction. This condition leads to a slow, roughly constant motion of the
diffusion region away from the wall, the so-called `X-line retreat'. The
typical retreat speed is ~0.1 times the Alfven speed. At the diffusion region,
ion flow pattern shows strong asymmetry and the ion stagnation point and the
X-line are not collocated. A surprise, however, is that the reconnection rate
remains the same unaffected by the retreat motion.


title: Metallicity-corrected Tip of the Red Giant Branch Distance to NGC 4258

abstract:
  We have determined the distance to NGC 4258 using observations made with the
Hubble Space Telescope (HST) and the Wide Field, Advanced Camera for Surveys
(ACS/WFC). We apply a modified technique that fully accounts for metallicity
effects on the use of the luminosity of the tip of the red giant branch (TRGB)
to determine one of the most precise TRGB distance moduli to date: u(TRGB) =
29.28 +/- 0.04 (random) +/- 0.12 (systematic) mag (7.18 +/- 0.13 +/- 0.40 Mpc).
We discuss this distance modulus with respect to other recent applications of
the TRGB method to NGC 4258, and with several other techniques (Cepheids and
masers) that are equally competitive in their precision, but different in their
systematics.


title:
Spectrum Sharing Between Cellular and Mobile Ad Hoc Networks:
  Transmission-Capacity Trade-Off

abstract:
  Spectrum sharing between wireless networks improves the efficiency of
spectrum usage, and thereby alleviates spectrum scarcity due to growing demands
for wireless broadband access. To improve the usual underutilization of the
cellular uplink spectrum, this paper studies spectrum sharing between a
cellular uplink and a mobile ad hoc networks. These networks access either all
frequency sub-channels or their disjoint sub-sets, called spectrum underlay and
spectrum overlay, respectively. Given these spectrum sharing methods, the
capacity trade-off between the coexisting networks is analyzed based on the
transmission capacity of a network with Poisson distributed transmitters. This
metric is defined as the maximum density of transmitters subject to an outage
constraint for a given signal-to-interference ratio (SIR). Using tools from
stochastic geometry, the transmission-capacity trade-off between the coexisting
networks is analyzed, where both spectrum overlay and underlay as well as
successive interference cancelation (SIC) are considered. In particular, for
small target outage probability, the transmission capacities of the coexisting
networks are proved to satisfy a linear equation, whose coefficients depend on
the spectrum sharing method and whether SIC is applied. This linear equation
shows that spectrum overlay is more efficient than spectrum underlay.
Furthermore, this result also provides insight into the effects of different
network parameters on transmission capacities, including link diversity gains,
transmission distances, and the base station density. In particular, SIC is
shown to increase transmission capacities of both coexisting networks by a
linear factor, which depends on the interference-power threshold for qualifying
canceled interferers.


title:
Ergodic theory and visualization. II. Harmonic mesochronic plots
  visualize (quasi)periodic sets

abstract:
  We present a new method of analysis of measure-preserving dynamical systems,
based on frequency analysis and ergodic theory, which extends our earlier work
[1]. Our method employs the novel concept of harmonic time average [2], and is
realized as a computational algorithms for visualization of periodic and
quasi-periodic sets or arbitrary periodicity in the phase space. Besides
identifying all periodic sets, our method is useful in detecting chaotic phase
space regions with a good precision. The range of method's applicability is
illustrated using well-known Chirikov standard map, while its full potential is
presented by studying higher-dimensional measure-preserving systems, in
particular Froeschl\'e map and extended standard map.


title:
Measurements of polarized photo-pion production on longitudinally
  polarized HD and Implications for Convergence of the GDH Integral

abstract:
  We report new measurements of inclusive pion production from frozen-spin HD
for polarized photon beams covering the Delta(1232) resonance. These provide
data simultaneously on both H and D with nearly complete angular distributions
of the spin-difference cross sections entering the Gerasimov-Drell-Hearn (GDH)
sum rule. Recent results from Mainz and Bonn exceed the GDH prediction for the
proton by 22 microbarns, suggesting as yet unmeasured high-energy components.
Our pi0 data reveal a different angular dependence than assumed in Mainz
analyses and integrate to a value that is 18 microbarns lower, suggesting a
more rapid convergence. Our results for deuterium are somewhat lower than
published data, considerably more precise and generally lower than available
calculations.


title: Supersymmetric Multi-trace Boundary Conditions in AdS

abstract:
  Boundary conditions for massive fermions are investigated in AdS_d for $d \ge
2$. For fermion masses in the range $0 \le |m| < 1/2\ell$ with $\ell$ the AdS
length, the standard notion of normalizeability allows a choice of boundary
conditions. As in the case of scalars at or slightly above the
Breitenlohner-Freedman (BF) bound, such boundary conditions correspond to
multi-trace deformations of any CFT dual. By constructing appropriate boundary
superfields, for d=3,4,5 we identify joint scalar/fermion boundary conditions
which preserve either ${\cal N}=1$ supersymmetry or ${\cal N}=1$ superconformal
symmetry on the boundary. In particular, we identify boundary conditions
corresponding via AdS/CFT (at large N) to a 595-parameter family of
double-trace marginal deformations of the low-energy theory of N M2-branes
which preserve ${\cal N} =1$ superconformal symmetry. We also establish that
(at large N and large 't Hooft coupling $\lambda$) there are no marginal or
relevant multi-trace deformations of 3+1 ${\cal N} =4$ super Yang-Mills which
preserve even ${\cal N}=1$ supersymmetry.


title:
Tightly-bound Cooper pair, quasiparticle kinks and clues on the pairing
  potential in a high Tc FeAs Superconductor

abstract:
  We present a systematic photoemission study of the newly discovered high Tc
superconductor class (Sr/Ba)1-xKxFe2As2. By utilizing a unique photon energy
range and scattering geometry we resolve the details of the single particle
dynamics of interacting electrons on the central Fermi surfaces of this series
which shows overall strong coupling behavior (2D/kBTc = 6). Quasiparticle
dispersion kinks are observed in a binding energy range of 15 to 50 meV which
matches the magnetic excitation energy scales (parameterized by J1,J2). The
size of the Cooper pair wavefunction is found to be less than 20A indicating a
short in-plane scale uncharacteristic of a BCS-phonon scenario but suggestive
of a phase factor in the global order parameter. The kink likely reflects
contributions from the strongly frustrated fluctuating spin excitations and the
soft phonons around 20-40 meV. Our results provide important clue to the nature
of the pairing potential realized in these superconductors.


title: Jamming I: A volume function for jammed matter

abstract:
  We introduce a "Hamiltonian"-like function, called the volume function,
indispensable to describe the ensemble of jammed matter such as granular
materials and emulsions from a geometrical point of view. The volume function
represents the available volume of each particle in the jammed systems. At the
microscopic level, we show that the volume function is the Voronoi volume
associated to each particle and in turn we provide an analytical formula for
the Voronoi volume in terms of the contact network, valid for any dimension. We
then develop a statistical theory for the probability distribution of the
volumes in 3d to calculate an average volume function coarse-grained at a
mesoscopic level. The salient result is the discovery of a mesoscopic volume
function inversely proportional to the coordination number. Our analysis is the
first step toward the calculation of macroscopic observables and equations of
state using the statistical mechanics of jammed matter, when supplemented by
the condition of mechanical equilibrium of jamming that properly defines jammed
matter at the ensemble level.


title: Ab-initio shell model with a core

abstract:
  We construct effective 2- and 3-body Hamiltonians for the p-shell by
performing 12\hbar\Omega ab initio no-core shell model (NCSM) calculations for
A=6 and 7 nuclei and explicitly projecting the many-body Hamiltonians onto the
0\hbar\Omega space. We then separate these effective Hamiltonians into 0-, 1-
and 2-body contributions (also 3-body for A=7) and analyze the systematic
behavior of these different parts as a function of the mass number A and size
of the NCSM basis space. The role of effective 3- and higher-body interactions
for A>6 is investigated and discussed.


title:
Interferometric imaging of the high-redshift radio galaxy, 4C60.07: An
  SMA, Spitzer and VLA study reveals a binary AGN/starburst

abstract:
  High-resolution submm imaging of the HzRG, 4C60.07, at z=3.8, has revealed
two dusty components. Spitzer imaging shows that one of these components (B) is
coincident with an extremely red AGN, offset by ~4" (~30 kpc) from the HzRG
core. The other submm component (A) - resolved by our beam and devoid of
emission at 3.6-8.0um - lies between B and the HzRG core. Since the HzRG was
discovered via its young, steep-spectrum lobes and their creation was likely
triggered by the interaction, we argue that we are witnessing an early-stage
merger, prior to its eventual equilibrium state. The interaction is between the
host galaxy of an actively-fueled BH, and a gas-rich starburst/AGN (B) marked
by the compact submm component and coincident with broad CO emission. `A' is a
plume of cold, dusty gas, associated with a narrow (~150 km/s) CO feature, and
may represent a short-lived tidal structure. It has been claimed that HzRGs and
SMGs differ only in the activity of their AGNs, but such complex submm
morphologies are seen only rarely amongst SMGs. Our study has important
implications: where a galaxy's gas is not aligned with its central BH, CO may
be an unreliable probe of dynamical mass, affecting work on the co-assembly of
BHs and spheroids. Our data support the picture wherein close binary AGN are
induced by mergers. They also raise the possibility that some supposedly
jet-induced starbursts may have formed co-evally with (yet independently of)
the radio jets, both triggered by the same interaction. We note that the HzRG
host would have gone unnoticed without its jets/companion, so there may be many
other unseen BHs at high redshift, lost in the sea of ~5 x 10^8 similarly
bright IRAC sources - sufficiently massive to drive a >10^27-W radio source,
yet practically invisible unless actively fueled (abridged).


title:
Topological character of hydrodynamic screening in suspensions of hard
  spheres: an example of universal phenomenon

abstract:
  Although in the case of polymer solutions the existence of hydrodynamic
screening is considered as established, use of the same methods for suspensions
of hard spheres so far have failed to produce similar results. In this work we
reconsider this problem. Using superposition of topological, combinatorial and
London-style qualitative arguments, we prove the existence of screening in
suspensions. We show that the nature of hydrodynamic screening in suspensions
is analogous to that known for the Meissner effect in superconductors. The
extent of screening depends on volume fraction of hard spheres. The zero volume
fraction limit corresponds to the normal state. The case of finite volume
fractions-to the mixed state typical for superconductors of the second kind.
Such a state is becoming fully "superconducting" at some critical volume
fraction for which the (zero frequency) relative viscosity diverges. Our
analytical results describing this divergence are in accord with known scaling
results obtained by Brady and Bicerano et al which are well supported by
experimental data. We provide theoretical explanation of the divergence of
relative viscosity in terms of a topological-type transition which
mathematically can be made isomorphic to the more familiar Bose-Einstein
condensation transition. Because of this, the methods developed in this work
are not limited to suspensions only. In concluding section we mention other
applications of the developed formalism ranging from turbulence and
magnetohydrodynamics to high temperature superconductors, QCD, string models,
etc.


title: Entropy of jammed matter

abstract:
  We investigate the nature of randomness in disordered packings of frictional
spheres. We calculate the entropy of 3D packings through the force and volume
ensemble of jammed matter, a mesoscopic ensemble and numerical simulations
using volume fluctuation analysis and graph theoretical methods. Equations of
state are obtained relating entropy, volume fraction and compactivity
characterizing the different states of jammed matter. At the mesoscopic level
the entropy vanishes at random close packing. The entropy of the jammed system
reveals that the random loose packings are more disordered than random close
packings, allowing for an unambiguous interpretation of both limits.


title: Factorization for generic jet production

abstract:
  Factorization is the central ingredient in any theoretical prediction for
collider experiments. We introduce a factorization formalism that can be
applied to any desired observable, like event shapes or jet observables, for
any number of jets and a wide range of jet algorithms in leptonic or hadronic
collisions. This is achieved by using soft-collinear effective theory to prove
the formal factorization of a generic fully-differential cross section in terms
of a hard coefficient, and generic jet and soft functions. In this formalism,
whether a given observable factorizes in the usual sense, depends on whether it
is inclusive enough, so the jet functions can be calculated perturbatively. The
factorization formula for any such observable immediately follows from our
general result, including the precise definition of the jet and soft functions
appropriate for the observable in question. As examples of our formalism, we
work out several results in two-jet production for both e+e- and pp collisions.
For the latter, we also comment on how our formalism allows one to treat
underlying events and beam remnants.


title: Jamming in two-dimensional packings

abstract:
  We investigate the existence of random close and random loose packing limits
in two-dimensional packings of monodisperse hard disks. A statistical mechanics
approach-- based on several approximations to predict the probability
distribution of volumes-- suggests the existence of the limiting densities of
the jammed packings according to their coordination number and compactivity.
This result has implications for the understanding of disordered states in the
disk packing problem as well as the existence of a putative glass transition in
two dimensional systems.


title: The Exceptionally Luminous Type II-L SN 2008es

abstract:
  We report on our early photometric and spectroscopic observations of the
extremely luminous Type II supernova (SN) 2008es. With an observed peak optical
magnitude of m_V = 17.8 and at a redshift z = 0.213, SN 2008es had a peak
absolute magnitude of M_V = -22.3, making it the second most luminous SN ever
observed. The photometric evolution of SN 2008es exhibits a fast decline rate
(~0.042 mag d^-1), similar to the extremely luminous Type II-L SN 2005ap. We
show that SN 2008es spectroscopically resembles the luminous Type II-L SN
1979C. Although the spectra of SN 2008es lack the narrow and intermediate-width
line emission typically associated with the interaction of a SN with the
circumstellar medium of its progenitor star, we argue that the extreme
luminosity of SN 2008es is powered via strong interaction with a dense,
optically thick circumstellar medium. The integrated bolometric luminosity of
SN 2008es yields a total radiated energy at ultraviolet and optical wavelengths
of >10^51 ergs. Finally, we examine the apparently anomalous rate at which the
Texas Supernova Search has discovered rare kinds of supernovae, including the
five most luminous supernovae observed to date, and find that their results are
consistent with those of other modern SN searches.


title:
Correlated Multi-Waveband Variability in the Blazar 3C~279 from 1996 to
  2007

abstract:
  We present the results of extensive multi-waveband monitoring of the blazar
3C~279 between 1996 and 2007 at X-ray energies (2-10 keV), optical R band, and
14.5 GHz, as well as imaging with the Very Long Baseline Array (VLBA) at 43
GHz. In all bands the power spectral density corresponds to "red noise" that
can be fit by a single power law over the sampled time scales. Variations in
flux at all three wavebands are significantly correlated. The time delay
between high and low frequency bands changes substantially on time scales of
years. A major multi-frequency flare in 2001 coincided with a swing of the jet
toward a more southerly direction, and in general the X-ray flux is modulated
by changes in the position angle of the jet near the core. The flux density in
the core at 43 GHz--increases in which indicate the appearance of new
superluminal knots--is significantly correlated with the X-ray flux.
  We decompose the X-ray and optical light curves into individual flares,
finding that X-ray leads optical variations (XO) in 6 flares, the reverse
occurs in 3 flares (OX), and there is essentially zero lag in 4 flares. Upon
comparing theoretical expectations with the data, we conclude that (1) XO
flares can be explained by gradual acceleration of radiating electrons to the
highest energies; (2) OX flares can result from either light-travel delays of
the seed photons (synchrotron self-Compton scattering) or gradients in maximum
electron energy behind shock fronts; and (3) events with similar X-ray and
optical radiative energy output originate well upstream of the 43 GHz core,
while those in which the optical radiative output dominates occur at or
downstream of the core.


title:
Scaling of degree correlations and the influence on diffusion in
  scale-free networks

abstract:
  Connectivity correlations play an important role in the structure of
scale-free networks. While several empirical studies exist, there is no general
theoretical analysis that can explain the largely varying behavior of real
networks. Here, we use scaling theory to quantify the degree of correlations in
the particular case of networks with a power-law degree distribution. These
networks are classified in terms of their correlation properties, revealing
additional information on their structure. For instance, the studied social
networks and the Internet at the router level are clustered around the line of
random networks, implying a strongly connected core of hubs. On the contrary,
some biological networks and the WWW exhibit strong anti-correlations. The
present approach can be used to study robustness or diffusion, where we find
that anti-correlations tend to accelerate the diffusion process.


title:
Jamming II: Edwards' statistical mechanics of random packings of hard
  spheres

abstract:
  The problem of finding the most efficient way to pack spheres has an
illustrious history, dating back to the crystalline arrays conjectured by
Kepler and the random geometries explored by Bernal in the 60's. This problem
finds applications spanning from the mathematician's pencil, the processing of
granular materials, the jamming and glass transitions, all the way to fruit
packing in every grocery. There are presently numerous experiments showing that
the loosest way to pack spheres gives a density of ~55% (RLP) while filling all
the loose voids results in a maximum density of ~63-64% (RCP). While those
values seem robustly true, to this date there is no physical explanation or
theoretical prediction for them. Here we show that random packings of
monodisperse hard spheres in 3d can pack between the densities 4/(4 + 2 \sqrt
3) or 53.6% and 6/(6 + 2 \sqrt 3) or 63.4%, defining RLP and RCP, respectively.
The reason for these limits arises from a statistical picture of jammed states
in which the RCP can be interpreted as the ground state of the ensemble of
jammed matter with zero compactivity, while the RLP arises in the infinite
compactivity limit. We combine an extended statistical mechanics approach 'a la
Edwards' (where the role traditionally played by the energy and temperature in
thermal systems is substituted by the volume and compactivity) with a
constraint on mechanical stability imposed by the isostatic condition.
Ultimately, our results lead to a phase diagram that provides a unifying view
of the disordered hard sphere packing problem.


title: The Katok-Spatzier Conjecture and Generalized Symmetries

abstract:
  Within the smooth category, an intertwining is exhibited between the global
rigidity of irreducible higher rank abelian Anosov actions on the n-torus and
the classification of equilibrium-free flows on the n-torus that possess
nontrivial generalized symmetries.


title:
Distribution of volumes and coordination number in jammed matter:
  mesoscopic ensemble

abstract:
  We investigate the distribution of the volume and coordination number
associated to each particle in a jammed packing of monodisperse hard sphere
using the mesoscopic ensemble developed in Nature 453, 606 (2008). Theory
predicts an exponential distribution of the orientational volumes for random
close packings and random loose packings. A comparison with computer generated
packings reveals deviations from the theoretical prediction in the volume
distribution, which can be better modeled by a compressed exponential function.
On the other hand, the average of the volumes is well reproduced by the theory
leading to good predictions of the limiting densities of RCP and RLP. We
discuss a more exact theory to capture the volume distribution in its entire
range. The available data suggests a plausible order/disorder transition
defining random close packings. Finally, we consider an extended ensemble to
calculate the coordination number distribution which is shown to be of an
exponential and inverse exponential form for coordinations larger and smaller
than the average, respectively, in reasonable agreement with the simulated
data.


title: Tensor gauge field localization in branes

abstract:
  In this work we study localization of a Kalb-Ramond tensorial gauge field on
a membrane described by real scalar fields. The membrane is embedded in an
AdS-type five dimensional bulk space, which mimic a Randall-Sundrum scenario.
First, we consider a membrane described by only a single real scalar field. In
that scenarios we find that there is no localized tensorial zero mode. When we
take into account branes described by two real scalar fields with internal
structures, we obtain again a non-localized zero mode for a Kalb-Ramond
tensorial gauge field. After modifying our model of one single scalar field by
coupling the dilaton to the Kalb-Ramond field, we find that this result is
changed. Furthermore, we analyze Kaluza-Klein massive modes and resonance
structures.


title: Pinned Repetitions in Symbolic Flows: Preliminary Results

abstract:
  We consider symbolic flows over finite alphabets and study certain kinds of
repetitions in these sequences. Positive and negative results for the existence
of such repetitions are given for codings of interval exchange transformations
and codings of quadratic polynomials.


title: Pressure and interaction measure of the gluon plasma

abstract:
  We explore the thermodynamics of the gluon plasma in SU(3) Yang-Mills theory
emerging from the non-trivial spatial dynamics of valence gluons. The lattice
data suggest that these gluons interact with each other linearly at large
spatial separations. At high temperatures, valence gluons should reproduce the
pressure of the non-interacting Stefan-Boltzmann plasma along with the leading
perturbative correction. These properties of valence gluons can be modeled in
terms of the integral over their trajectories. We calculate such a world-line
integral analytically and obtain the pressure and the interaction measure
$(\varepsilon-3p)/T^4$ of the gluon plasma. Additionally, we account for the
contributions of stochastic background fields to these thermodynamic
quantities. The results turn out to be in a good agreement with the
corresponding lattice data. In particular, the lattice-simulated peak of the
interaction measure near the deconfinement critical temperature is reproduced.


title: Laws of Population Growth

abstract:
  An important issue in the study of cities is defining a metropolitan area, as
different definitions affect the statistical distribution of urban activity. A
commonly employed method of defining a metropolitan area is the Metropolitan
Statistical Areas (MSA), based on rules attempting to capture the notion of
city as a functional economic region, and is constructed using experience. The
MSA is time-consuming and is typically constructed only for a subset (few
hundreds) of the most highly populated cities. Here, we introduce a new method
to designate metropolitan areas, denoted the "City Clustering Algorithm" (CCA).
The CCA is based on spatial distributions of the population at a fine
geographic scale, defining a city beyond the scope of its administrative
boundaries. We use the CCA to examine Gibrat's law of proportional growth,
postulating that the mean and standard deviation of the growth rate of cities
are constant, independent of city size. We find that the mean growth rate of a
cluster utilizing the CCA exhibits deviations from Gibrat's law, and that the
standard deviation decreases as a power-law with respect to the city size. The
CCA allows for the study of the underlying process leading to these deviations,
shown to arise from the existence of long-range spatial correlations in the
population growth. These results have socio-political implications, such as
those pertaining to the location of new economic development in cities of
varied size.


title: Energy-landscape network approach to the glass transition

abstract:
  We study the energy-landscape network of Lennard-Jones clusters as a model of
a glass forming system. We find the stable basins and the first order saddles
connecting them, and identify them with the network nodes and links,
respectively. We analyze the network properties and model the system's
evolution. Using the model, we explore the system's response to varying cooling
rates, and reproduce many of the glass transition properties. We also find that
the static network structure gives rise to a critical temperature where a
percolation transition breaks down the space of configurations into
disconnected components. Finally, we discuss the possibility of studying the
system mathematically with a trap-model generalized to networks.


title: A theory for viral capsid assembly around electrostatic cores

abstract:
  We develop equilibrium and kinetic theories that describe the assembly of
viral capsid proteins on a charged central core, as seen in recent experiments
in which brome mosaic virus (BMV) capsids assemble around nanoparticles
functionalized with polyelectrolyte. We model interactions between capsid
proteins and nanoparticle surfaces as the interaction of polyelectrolyte
brushes with opposite charge, using the nonlinear Poisson Boltzmann equation.
The models predict that there is a threshold density of functionalized charge,
above which capsids efficiently assemble around nanoparticles, and that light
scatter intensity increases rapidly at early times, without the lag phase
characteristic of empty capsid assembly. These predictions are consistent with,
and enable interpretation of, preliminary experimental data. However, the
models predict a stronger dependence of nanoparticle incorporation efficiency
on functionalized charge density than measured in experiments, and do not
completely capture a logarithmic growth phase seen in experimental light
scatter. These discrepancies may suggest the presence of metastable disordered
states in the experimental system. In addition to discussing future experiments
for nanoparticle-capsid systems, we discuss broader implications for
understanding assembly around charged cores such as nucleic acids.


title:
Alignment Dynamics of Single-Walled Carbon Nanotubes in Pulsed Ultrahigh
  Magnetic Fields

abstract:
  We have measured the dynamic alignment properties of single-walled carbon
nanotube (SWNT) suspensions in pulsed high magnetic fields through linear
dichroism spectroscopy. Millisecond-duration pulsed high magnetic fields up to
56 T as well as microsecond-duration pulsed ultrahigh magnetic fields up to 166
T were used. Due to their anisotropic magnetic properties, SWNTs align in an
applied magnetic field, and because of their anisotropic optical properties,
aligned SWNTs show linear dichroism. The characteristics of their overall
alignment depend on several factors, including the viscosity and temperature of
the suspending solvent, the degree of anisotropy of nanotube magnetic
susceptibilities, the nanotube length distribution, the degree of nanotube
bundling, and the strength and duration of the applied magnetic field. In order
to explain our data, we have developed a theoretical model based on the
Smoluchowski equation for rigid rods that accurately reproduces the salient
features of the experimental data.


title: Fractal and Transfractal Scale-Free Networks

abstract:
  Self-similarity is a property of fractal structures, a concept introduced by
Mandelbrot and one of the fundamental mathematical results of the 20th century.
The importance of fractal geometry stems from the fact that these structures
were recognized in numerous examples in Nature, from the coexistence of
liquid/gas at the critical point of evaporation of water, to snowflakes, to the
tortuous coastline of the Norwegian fjords, to the behavior of many complex
systems such as economic data, or the complex patterns of human agglomeration.
Here we review the recent advances in self-similarity of complex networks and
its relation to transport, diffusion, percolations and other topological
properties such us degree distribution, modularity, and degree-degree
correlations.


title:
Asymptotic behavior of the mean square displacement of the Brownian
  parametric oscillator near the singular point

abstract:
  A parametric oscillator with damping driven by white noise is studied. The
mean square displacement (MSD) in the long-time limit is derived analytically
for the case that the static force vanishes, which was not treated in the past
work \cite{tashiro07}. The formula is asymptotic but is applicable to a general
periodic function. On the basis of this formula, some periodic functions
reducing MSD remarkably are proposed.


title: Challenges to the DGP Model from Horizon-Scale Growth and Geometry

abstract:
  We conduct a Markov Chain Monte Carlo study of the Dvali-Gabadadze-Porrati
(DGP) self-accelerating braneworld scenario given the cosmic microwave
background (CMB) anisotropy, supernovae and Hubble constant data by
implementing an effective dark energy prescription for modified gravity into a
standard Einstein-Boltzmann code. We find no way to alleviate the tension
between distance measures and horizon scale growth in this model. Growth
alterations due to perturbations propagating into the bulk appear as excess CMB
anisotropy at the lowest multipoles. In a flat cosmology, the maximum
likelihood DGP model is nominally a 5.3 sigma poorer fit than Lambda CDM.
Curvature can reduce the tension between distance measures but only at the
expense of exacerbating the problem with growth leading to a 4.8 sigma result
that is dominated by the low multipole CMB temperature spectrum. While changing
the initial conditions to reduce large scale power can flatten the temperature
spectrum, this also suppresses the large angle polarization spectrum in
violation of recent results from WMAP5. The failure of this model highlights
the power of combining growth and distance measures in cosmology as a test of
gravity on the largest scales.


title:
How to make large, void free dust clusters in dusty plasma under
  microgravity

abstract:
  Collections of micrometer sized solid particles immersed in plamsa are used
to mimic many systems from solid state and fluid physics, due to their strong
electrostatic interaction, their large inertia, and the fact that they are
large enough to be visualized with ordinary optics. On Earth, gravity restricts
the so called dusty plasma systems to thin, two-dimensional layers, unless
special experimental geometries are used, involving heated or cooled electrons,
and/or the use of dielectric materials.In micro-gravity experiments, the
formation of a dust-free void breaks the isotropy of three-dimensional dusty
plasma systems. In order to do real three-dimensional experiments, this void
has somehow to be closed. In this paper, we use a fully self-consistent fluid
model to study the closure of a void in a micro-gravity experiment, by lowering
the driving potential. The analysis goes beyond the simple description of the
virtual void, which describes the formation of a void without taking the dust
into account. We show that self-organization plays an important role in void
formation and void closure, which also allows a reversed scheme, where a
discharge is run at low driving potentials and small batches of dust are added.
No hysteresis is found this way. Finally, we compare our results to recent
experiments and find good agreement,but only when we do not take
charge-exchange collisions into account.


title:
The Optical Gravitational Lensing Experiment. The OGLE-III Catalog of
  Variable Stars. I. Classical Cepheids in the Large Magellanic Cloud

abstract:
  We present the first part of a new catalog of variable stars (OIII-CVS)
compiled from the data collected in the course of the third phase of the
Optical Gravitational Lensing Experiment (OGLE-III). In this paper we describe
the catalog of 3361 classical Cepheids detected in the ~40 square degrees area
in the Large Magellanic Cloud. The sample consists of 1848 fundamental-mode
(F), 1228 first-overtone (1O), 14 second-overtone (2O), 61 double-mode F/1O,
203 double-mode 1O/2O, 2 double-mode 1O/3O, and 5 triple-mode classical
Cepheids. This sample is supplemented by the list of 23 ultra-low amplitude
variable stars which may be Cepheids entering or exiting instability strip.
  The catalog data include VI high-quality photometry collected since 2001, and
for some stars supplemented by the OGLE-II photometry obtained between 1997 and
2000. We provide basic parameters of the stars: coordinates, periods, mean
magnitudes, amplitudes and parameters of the Fourier light curve
decompositions. Individual objects of particular interest are discussed,
including single-mode second-overtone Cepheids, multiperiodic pulsators with
unusual period ratios or Cepheids in eclipsing binary systems.
  We discuss the variations of the Fourier coefficients with periods and point
out on the sharp feature for periods around 0.35 days of first-overtone
Cepheids, which can be explained by the occurrence of 2:1 resonance between the
first and fifth overtones. Similar behavior at P=3 days for 1O Cepheids and
P=10 days for F Cepheids are also interpreted as an effect of resonances
between two radial modes. We fit the period-luminosity relations to our sample
of Cepheids and compare these functions with previous determinations.


title: Sample size effects in multivariate fitting of correlated data

abstract:
  A common problem in analysis of experiments or in lattice QCD simulations is
fitting a parameterized model to the average over a number of samples of
correlated data values. If the number of samples is not infinite, estimates of
the variance of the parameters ("error bars") and of the goodness of fit are
affected. We illustrate these problems with numerical simulations, and
calculate approximate corrections to the variance of the parameters for
estimates made in the standard way from derivatives of the parameters'
probability distribution as well as from jackknife and bootstrap estimates.


title: Expansion of a quantum gas released from an optical lattice

abstract:
  We analyze the interference pattern produced by ultracold atoms released from
an optical lattice. Such interference patterns are commonly interpreted as the
momentum distributions of the trapped quantum gas. We show that for finite
time-of-flights the resulting density distribution can, however, be
significantly altered, similar to a near-field diffraction regime in optics. We
illustrate our findings with a simple model and realistic quantum Monte Carlo
simulations for bosonic atoms, and compare the latter to experiments.


title: Multidimensional Chebyshev Systems - just a definition

abstract:
  We provide a definition of Multidimensional Chebyshev Systems of order N
which is satisfied by the solutions of a wide class of elliptic equations of
order 2N. This definition generalizes a very large class of Extended Complete
Chebyshev systems in the one-dimensional case. This is the first of a series of
papers in this area, which solves the longstanding problem of finding a
satisfactory multidimensional generalization of the classical Chebyshev systems
introduced already by A. Markov more than hundered years ago, and studied later
by S. Bernstein and M. Krein.


title:
Relativistic Iron Line Emission from the Neutron Star Low-mass X-ray
  Binary 4U 1636-536

abstract:
  We present an analysis of XMM-Newton and RXTE data from three observations of
the neutron star LMXB 4U 1636-536. The X-ray spectra show clear evidence of a
broad, asymmetric iron emission line extending over the energy range 4-9 keV.
The line profile is consistent with relativistically broadened Fe K-alpha
emission from the inner accretion disk. The Fe K-alpha line in 4U 1636-536 is
considerably broader than the asymmetric iron lines recently found in other
neutron star LMXBs, which indicates a high disk inclination. We find evidence
that the broad iron line feature is a combination of several K-alpha lines from
iron in different ionization states.


title: Proton elastic impact factors for two, three, and four gluons

abstract:
  In this talk we report on recent calculation of high energy baryon scattering
amplitudes in QCD. Elastic baryon impact factors for two, three and four gluons
are presented and their energy evolution is described that incorporates
unitarity corrections. We find that the baryon couples directly to the BFKL
Pomeron, to the BKP odderon and to a new state, a three-gluon BKP Pomeron. The
new state may decay into four gluons with a new 3 -> 4 transition vertex. This
vertex defines the transition amplitude of the three-gluon BKP Pomeron state
into two BFKL Pomerons.


title: Searching for odderon in exclusive vector meson hadroproduction

abstract:
  In this talk estimates are presented of the odderon contributions to the
exclusive J/psi and Upsilon production cross-sections at the Tevatron and the
Large Hadron Collider. The obtained cross-sections are compared to
cross-sections of the dominant background subprocesses mediated by the photon
exchange. Possible experimental cuts are proposed that reduce the photon
background.


title: Scalar $QCD_{4}$ on the null-plane

abstract:
  We have studied the null-plane hamiltonian structure of the free Yang-Mills
fields and the scalar chromodynamics ($SQCD_{4}$). Following the Dirac's
procedure for constrained systems we have performed a detailed analysis of the
constraint structure of both models and we give the generalized Dirac brackets
for the physical variables. In the free Yang-Mills case, using the
correspondence principle in the Dirac's brackets we obtain the same commutators
present in the literature.


title: Faster strain fluctuation methods through partial volume updates

abstract:
  Elastic systems that are spatially heterogeneous in their mechanical response
pose special challenges for molecular simulations. Standard methods for
sampling thermal fluctuations of a system's size and shape proceed through a
series of homogeneous deformations, whose magnitudes can be severely restricted
by its stiffest parts. Here we present a Monte Carlo algorithm designed to
circumvent this difficulty, which can be prohibitive in many systems of modern
interest. By deforming randomly selected subvolumes alone, it naturally
distributes the amplitude of spontaneous elastic fluctuations according to
intrinsic heterogeneity. We describe in detail implementations of such "slice
moves" that are consistent with detailed balance. Their practical application
is illustrated for a random network of cross-linked polymers.


title: On isoperimetric profiles of algebras

abstract:
  Isoperimetric profile in algebras was first introduced by Gromov. We study
the behavior of the isoperimetric profile under various ring theoretic
constructions and its relation with the Gelfand-Kirillov dimension.


title:
Every Computably Enumerable Random Real Is Provably Computably
  Enumerable Random

abstract:
  We prove that every computably enumerable (c.e.) random real is provable in
Peano Arithmetic (PA) to be c.e. random. A major step in the proof is to show
that the theorem stating that "a real is c.e. and random iff it is the halting
probability of a universal prefix-free Turing machine" can be proven in PA. Our
proof, which is simpler than the standard one, can also be used for the
original theorem.
  Our positive result can be contrasted with the case of computable functions,
where not every computable function is provably computable in PA, or even more
interestingly, with the fact that almost all random finite strings are not
provably random in PA.
  We also prove two negative results: a) there exists a universal machine whose
universality cannot be proved in PA, b) there exists a universal machine $U$
such that, based on $U$, PA cannot prove the randomness of its halting
probability.
  The paper also includes a sharper form of the Kraft-Chaitin Theorem, as well
as a formal proof of this theorem written with the proof assistant Isabelle.


title:
Possibility of single biomolecular imaging with coherent amplification
  of weak scattering X-ray photons

abstract:
  The number of photons available by coherent X-ray scattering from a single
biomolecule is considerably less because of the extremely small
elastic-scattering cross-section and low damage threshold. Even with a high
X-ray flux of 3 x 10to 12 photons per 100-nm-diameter spot and an ultrashort
pulse of 10 fs driven by a future X-ray free electron laser (X-ray FEL), it has
been predicted that only a few 100 photons will be available by scattering from
a single lysozyme molecule. In this paper I propose a new method: instead of
directly observing the photons scattered from the sample, we amplify the
scattered waves by superimposing an intense coherent reference pump wave on it
and record the resulting interference pattern using a planar X-ray detector,
similar to technique followed in holography. Using a nanosized gold particle as
a reference pump wave source, we can collect 10 to 4 ~ 10 to 5 photons in
single shot imaging where the signal from a single biomolecule is amplified and
recorded as 2D diffraction intensity data. To recover the phase information and
reconstruct the image, the iterative phase retrieval technique will be
applicable. However, the technical difficulty is how to precisely reconstruct
faint image of the single bio-molecular in Angstrom resolution, whose intensity
is much lower than the bright gold particle linked to it. In order to solve
this problem, I propose a new scheme that combines the iterative
phase-retrieval on reference pump wave and digital Fourier transform
holography.


title: Better Bounds for Frequency Moments in Random-Order Streams

abstract:
  Estimating frequency moments of data streams is a very well studied problem
and tight bounds are known on the amount of space that is necessary and
sufficient when the stream is adversarially ordered. Recently, motivated by
various practical considerations and applications in learning and statistics,
there has been growing interest into studying streams that are randomly
ordered. In the paper we improve the previous lower bounds on the space
required to estimate the frequency moments of a randomly ordered streams.


title: Breaking GUT Groups in F-Theory

abstract:
  We consider the possibility of breaking the GUT group to the Standard Model
gauge group in F-theory compactifications by turning on certain U(1) fluxes. We
show that the requirement of massless hypercharge is equivalent to a
topological constraint on the UV completion of the local model. The possibility
of this mechanism is intrinsic to F-theory. We address some of the
phenomenological signatures of this scenario. We show that our models predict
monopoles as in conventional GUT models. We discuss in detail the leading
threshold corrections to the gauge kinetic terms and their effect on
unification. They turn out to be related to Ray-Singer torsion. We also discuss
the issue of proton decay in F-theory models and explain how to engineer models
which satisfy current experimental bounds.


title: Magnetic impurities on the surface of a topological insulator

abstract:
  The surface states of a topological insulator are described by an emergent
relativistic massless Dirac equation in 2+1 dimensions. In contrast to
graphene, there is an odd number of Dirac points, and the electron spin is
directly coupled to the momentum. We show that a magnetic impurity opens up a
local gap and suppresses the local density of states. Furthermore, the Dirac
electronic states mediate an RKKY interaction among the magnetic impurities
which is always ferromagnetic, whenever the chemical potential lies near the
Dirac point. These effects can be directly measured in STM experiments. We also
study the case of quenched disorder through a renormalization group analysis.


title:
A Bayesian method to set upper limits on the strength of a periodic
  gravitational wave signal from the remnant of SN1987A: possible applications
  in LIGO searches

abstract:
  We present a method that assesses the theoretical detection limit of a
Bayesian Markov chain Monte Carlo search for a periodic gravitational wave
signal emitted by a neutron star. Inverse probability yields an upper limit
estimate for the strength when a signal could not be detected in an observed
data set. The proposed method is based on Bayesian model comparison that
automatically quantifies Occam s Razor. It limits the complexity of a model by
favoring the most parsimonious model that explains the data. By comparing the
model with a signal from a pulsar to the null model that assumes solely noise,
we derive the detection probability and an estimate for the upper limit that a
search, for example, for a narrow-band emission for SN1987a, might yield on
data at the sensitivity of LIGO data for an observation time of one year.


title: Qubit phase-space: SU(n) coherent state P-representations

abstract:
  We introduce a phase-space representation for qubits and spin models. The
technique uses an SU(n) coherent state basis, and can equally be used for
either static or dynamical simulations. We review previously known definitions
and operator identities, and show how these can be used to define an
off-diagonal, positive phase-space representation analogous to the positive
P-function. As an illustration of the phase-space method, we use the example of
the Ising model, which has exact solutions for the finite temperature canonical
ensemble in two dimensions. We show how a canonical ensemble for an Ising model
of arbitrary structure can be efficiently simulated using SU(2) or atomic
coherent states. The technique utilizes a transformation from a canonical
(imaginary-time) weighted simulation to an equivalent unweighted real-time
simulation. The results are compared to the exactly soluble two-dimensional
case. We note that Ising models in one, two or three dimensions are potentially
achievable experimentally as a lattice-gas of ultra-cold atoms in optical
lattices. The technique is not restricted to canonical ensembles or to
Ising-like couplings. It is also able to be used for real-time evolution, and
for systems whose time-evolution follows a master-equation describing
decoherence and coupling to external reservoirs. The case of SU(n) phase-space
is used to describe n-level systems. In general, the requirement that
time-evolution is stochastic corresponds to a restriction to Hamiltonians and
master-equations that are quadratic in the group generators or generalized spin
operators.


title:
Higher Order Moments Generation by Mellin Transform for Compound Models
  of Clutter

abstract:
  The compound models of clutter statistics are found suitable to describe the
nonstationary nature of radar backscattering from high-resolution observations.
In this letter, we show that the properties of Mellin transform can be utilized
to generate higher order moments of simple and compound models of clutter
statistics in a compact manner.


title:
Relatively Open Gromov-Witten Invariants for Symplectic Manifolds of
  Lower Dimensions

abstract:
  Let $(X,\omega)$ be a compact symplectic manifold, $L$ be a Lagrangian
submanifold and $V$ be a codimension 2 symplectic submanifold of $X$, we
consider the pseudoholomorphic maps from a Riemann surface with boundary
$(\Sigma,\partial\Sigma)$ to the pair $(X,L)$ satisfying Lagrangian boundary
conditions and intersecting $V$. In some special cases, for instance, under the
semi-positivity condition, we study the stable moduli space of such open
pseudoholomorphic maps involving the intersection data. If $L\cap V=\emptyset$,
we study the problem of orientability of the moduli space. Moreover, assume
that there exists an anti-symplectic involution $\phi$ on $X$ such that $L$ is
the fixed point set of $\phi$ and $V$ is $\phi$-anti-invariant, then we define
the so-called "relatively open" invariants for the tuple $(X,\omega,V,\phi)$ if
$L$ is orientable and dim$X\le 6$. If $L$ is nonorientable, we define such
invariants under the condition that dim$X\le4$ and some additional restrictions
on the number of marked points on each boundary component of the domain.


title: Plaquette Order in the J1-J2-J3 model: a series expansion analysis

abstract:
  Series expansion based on the flow equation method is employed to study the
zero temperature properties of the spin-1/2 J1-J2-J3 antiferromagnet in two
dimensions. Starting from the exact limit of decoupled plaquettes in a
particular generalized J1-J2-J3 model we analyze the evolution of the ground
state energy and the elementary triplet excitations in powers of all three
inter-plaquette couplings up to fifth order. We find the plaquette phase to
remain stable over a wide range of exchange couplings and to connect
adiabatically up to the case of the plain J1-J2-J3 model, however not to the
J1-J2 model at J3=0. Besides confirming the existence of such a phase, recently
predicted by Mambrini, et al. [Phys. Rev. B 74, 144422 [2006)], we estimate its
extent by Dlog-Pade analysis of the critical lines that result from closure of
the triplet gap.


title: The distribution of the irreducibles in an algebraic number field

abstract:
  We study the distribution of principal ideals generated by irreducible
elements in an algebraic number field.


title:
The limited role of non-native contacts in folding pathways of a lattice
  protein

abstract:
  Models of protein energetics which neglect interactions between amino acids
that are not adjacent in the native state, such as the Go model, encode or
underlie many influential ideas on protein folding. Implicit in this
simplification is a crucial assumption that has never been critically evaluated
in a broad context: Detailed mechanisms of protein folding are not biased by
non-native contacts, typically imagined as a consequence of sequence design
and/or topology. Here we present, using computer simulations of a well-studied
lattice heteropolymer model, the first systematic test of this oft-assumed
correspondence over the statistically significant range of hundreds of
thousands of amino acid sequences, and a concomitantly diverse set of folding
pathways. Enabled by a novel means of fingerprinting folding trajectories, our
study reveals a profound insensitivity of the order in which native contacts
accumulate to the omission of non-native interactions. Contrary to conventional
thinking, this robustness does not arise from topological restrictions and does
not depend on folding rate. We find instead that the crucial factor in
discriminating among topological pathways is the heterogeneity of native
contact energies. Our results challenge conventional thinking on the
relationship between sequence design and free energy landscapes for protein
folding, and help justify the widespread use of Go-like models to scrutinize
detailed folding mechanisms of real proteins.


title:
Digital PCR provides sensitive and absolute calibration for high
  throughput sequencing

abstract:
  Several of the next generation sequencers are limited in their sample
preparation process by the need to make an absolute measurement of the number
of template molecules in the library to be sequenced. As currently practiced,
the practical effects of this requirement compromise sequencing performance,
both by requiring large amounts of sample DNA and by requiring extra sequencing
runs to be performed. We used digital PCR to quantitate sequencing libraries,
and demonstrated its sensitivity and robustness by preparing and sequencing
libraries from subnanogram amounts of bacterial and human DNA on the 454 and
Solexa sequencing platforms. This assay allows absolute quantitation and
eliminates uncertainties associated with the construction and application of
standard curves. The digital PCR platform consumes subfemptogram amounts of the
sequencing library and gives highly accurate results, allowing the optimal DNA
concentration to be used in setting up sequencing runs without costly and
time-consuming titration techniques. This approach also reduces the input
sample requirement more than 1000-fold: from micrograms of DNA to less than a
nanogram.


title:
On the Importance of the Interclump Medium for Superionization: O VI
  Formation in the Wind of Zeta Pup

abstract:
  We have studied superionization and X-ray line formation in the spectra of
Zeta Pup using our new stellar atmosphere code (XCMFGEN) that can be used to
simultaneously analyze optical, UV, and X-ray observations. Here, we present
results on the formation of the O VI ll1032, 1038 doublet. Our simulations,
supported by simple theoretical calculations, show that clumped wind models
that assume void in the interclump space cannot reproduce the observed O VI
profiles. However, enough O VI can be produced if the voids are filled by a low
density gas. The recombination of O VI is very efficient in the dense material
but in the tenuous interclump region an observable amount of O VI can be
maintained. We also find that different UV resonance lines are sensitive to
different density regimes in Zeta Pup : C IV is almost exclusively formed
within the densest regions, while the majority of O VI resides between clumps.
N V is an intermediate case, with contributions from both the tenuous gas and
clumps.


title: Sum of squares of degrees in a graph

abstract:
  Let $\G(v,e)$ be the set of all simple graphs with $v$ vertices and $e$ edges
and let $P_2(G)=\sum d_i^2$ denote the sum of the squares of the degrees, $d_1,
>..., d_v$, of the vertices of $G$.
  It is known that the maximum value of $P_2(G)$ for $G \in \G(v,e)$ occurs at
one or both of two special graphs in $\G(v,e)$--the \qs graph or the \qc graph.
For each pair $(v,e)$, we determine which of these two graphs has the larger
value of $P_2(G)$. We also determine all pairs $(v,e)$ for which the values of
$P_2(G)$ are the same for the \qs and the \qc graph. In addition to the \qs and
\qc graphs, we find all other graphs in $\G(v,e)$ for which the maximum value
of $P_2(G)$ is attained. Density questions posed by previous authors are
examined.


title:
Normal diffusion in crystal structures and higher-dimensional billiard
  models with gaps

abstract:
  We show, both heuristically and numerically, that three-dimensional periodic
Lorentz gases -- clouds of particles scattering off crystalline arrays of hard
spheres -- often exhibit normal diffusion, even when there are gaps through
which particles can travel without ever colliding, i.e., when the system has an
infinite horizon. This is the case provided that these gaps are not "too big",
as measured by their dimension. The results are illustrated with simulations of
a simple three-dimensional model having different types of diffusive regime,
and are then extended to higher-dimensional billiard models, which include
hard-sphere fluids.


title: Cosmology for Particle Physicists

abstract:
  In these notes we present a selection of topics, each section approximately
amounting to one lecture. We begin with a brief recapitulation of General
Relativity, and the Standard Model of Cosmology. This is followed by lectures
on important signatures of the remote past. These include : (i) inflation, (ii)
density perturbations leading to galaxy formation, (iii) study of hot and cold
relics decoupled from the remaining constituents, some of which can be
candidates for Dark Matter, (iv) baryon asymmetry of the Universe.


title:
The incommensurate magnetic structure of YMn2O5: a stringent test of the
  multiferroic mechanism

abstract:
  We have determined the magnetic structure of the low-temperature
incommensurate phase of multiferroic YMn2O5 using single-crystal neutron
diffraction. By employing corepresentation analysis, we have ensured full
compliance with both symmetry and physical constraints, so that the electrical
polarization must lie along the b axis, as observed. The evolution of the spin
components and propagation through the commensurate-incommensurate phase
boundary points unambiguously at the exchange-striction mechanism as the
primary driving force for ferroelectricity.


title: Drell-Yan Cross Section in the Jet Calculus Scheme

abstract:
  We calculate factorized cross sections for lepton pair production mediated by
a virtual photon in hadron-hadron collisions using the jet calculus scheme, in
which a kinematical constraint due to parton radiation is taken into account.
This method guarantees a proper phase space boundary for subtraction terms.
Some properties of the calculated cross sections are examined. We also discuss
matching between the hard scattering cross sections and parton showers at the
next-to-leading logarithmic (NLL) order of quantum chromodynamics (QCD).


title: Implicit-Explicit Variational Integration of Highly Oscillatory Problems

abstract:
  In this paper, we derive a variational integrator for certain highly
oscillatory problems in mechanics. To do this, we take a new approach to the
splitting of fast and slow potential forces: rather than splitting these forces
at the level of the differential equations or the Hamiltonian, we split the two
potentials with respect to the Lagrangian action integral. By using a different
quadrature rule to approximate the contribution of each potential to the
action, we arrive at a geometric integrator that is implicit in the fast force
and explicit in the slow force. This can allow for significantly longer time
steps to be taken (compared to standard explicit methods, such as
St\"ormer/Verlet) at the cost of only a linear solve rather than a full
nonlinear solve. We also analyze the stability of this method, in particular
proving that it eliminates the linear resonance instabilities that can arise
with explicit multiple-time-stepping methods. Next, we perform some numerical
experiments, studying the behavior of this integrator for two test problems: a
system of coupled linear oscillators, for which we compare against the
resonance behavior of the r-RESPA method; and slow energy exchange in the
Fermi--Pasta--Ulam problem, which couples fast linear oscillators with slow
nonlinear oscillators. Finally, we prove that this integrator accurately
preserves the slow energy exchange between the fast oscillatory components,
which explains the numerical behavior observed for the Fermi--Pasta--Ulam
problem.


title:
Reconstructing the Cosmic Expansion History up to Redshift z=6.29 with
  the Calibrated Gamma-Ray Bursts

abstract:
  Recently, Gamma-Ray Bursts (GRBs) were proposed to be a complementary
cosmological probe to type Ia supernovae (SNIa). GRBs have been advocated to be
standard candles since several empirical GRB luminosity relations were proposed
as distance indicators. However, there is a so-called circularity problem in
the direct use of GRBs. Recently, a new idea to calibrate GRBs in a completely
cosmology independent manner has been proposed, and the circularity problem can
be solved. In the present work, following the method proposed by Liang {\it et
al.}, we calibrate 70 GRBs with the Amati relation using 307 SNIa. Then,
following the method proposed by Shafieloo {\it et al.}, we smoothly
reconstruct the cosmic expansion history up to redshift $z=6.29$ with the
calibrated GRBs. We find some new features in the reconstructed results.


title: Persistent Clustering and a Theorem of J. Kleinberg

abstract:
  We construct a framework for studying clustering algorithms, which includes
two key ideas: persistence and functoriality. The first encodes the idea that
the output of a clustering scheme should carry a multiresolution structure, the
second the idea that one should be able to compare the results of clustering
algorithms as one varies the data set, for example by adding points or by
applying functions to it. We show that within this framework, one can prove a
theorem analogous to one of J. Kleinberg, in which one obtains an existence and
uniqueness theorem instead of a non-existence result. We explore further
properties of this unique scheme, stability and convergence are established.


title:
An Exploration of a Discrete Rhombohedral Lattice; of Possible
  Engineering or Physical Relevance (Revised Version)

abstract:
  A particular discrete rhombohedral lattice consisting of four symmetrically
interlaced cuboctahedral point lattices is described that is interesting
because of the high degree of symmetry it exhibits. The four constituent
cuboctahedral lattices are denoted by four colours and the composite lattice is
referred to as a 4-colour rhombohedral lattice. Each point of the 4-colour
lattice can be referenced by an integer 4-tuple containing only the positive
non-zero integers (the counting numbers). The relationship between the discrete
rhombohedral lattice and a discrete Cartesian lattice is explained. Some
interesting aspects of the lattice and of the counting-number 4-tuple
coordinate system are pointed out.


title:
A note on the Chevalley-Eilenberg Cohomology for the Galilei and
  Poincare Algebras

abstract:
  We construct in a systematic way the complete Chevalley-Eilenberg cohomology
at form degree two, three and four for the Galilei and Poincare groups. The
corresponding non-trivial forms belong to certain representations of the
spatial rotation (Lorentz) group. In the case of two forms they give all
possible central and non-central extensions of the Galilei group (and all
non-central extensions of the Poincare group). The procedure developed in this
paper can be applied to any space-time symmetry group.


title: Connection between non-Abelian tensor gauge fields and open strings

abstract:
  We compare the structure of the tree level scattering amplitudes in
non-Abelian tensor gauge field theory and in open string theory with Chan-Paton
charges. We limit ourselves considering only lower rank tensor fields in both
theories. We identify the symmetric and antisymmetric components of the second
rank tensor gauge field with the string excitations on the third and forth
levels. In the process of this identification we have been selecting only those
parts of the tree level scattering amplitudes in the open string theory which
have dimensionless coupling constants in four dimensions. It seems that this
subclass of tree level scattering amplitudes may provide important information
about the structure of the open string theory and most probably it is
equivalent to the non-Abelian tensor gauge field theory.


title: All Oxide Ferromagnet/Semiconductor Epitaxial Heterostructures

abstract:
  Oxide based ferromagnet/semiconductor heterostructures offer substantial
advantages for spin electronics. We have grown (111) oriented Fe3O4 thin films
and Fe3O4/ZnO heterostructures on ZnO(0001) and Al2O3(0001) substrates by
pulsed laser deposition. High quality crystalline films with mosaic spread as
small as 0.03 degree, sharp interfaces, and rms surface roughness of 0.3 nm
were achieved. Magnetization measurements show clear ferromagnetic behavior of
the magnetite layers with a saturation magnetization of 3.2 muB/f.u. at 300 K.
Our results demonstrate that the Fe3O4/ZnO system is an intriguing and
promising candidate for the realization of multi-functional heterostructures.


title:
Comparing human and automatic thesaurus mapping approaches in the
  agricultural domain

abstract:
  Knowledge organization systems (KOS), like thesauri and other controlled
vocabularies, are used to provide subject access to information systems across
the web. Due to the heterogeneity of these systems, mapping between
vocabularies becomes crucial for retrieving relevant information. However,
mapping thesauri is a laborious task, and thus big efforts are being made to
automate the mapping process. This paper examines two mapping approaches
involving the agricultural thesaurus AGROVOC, one machine-created and one human
created. We are addressing the basic question "What are the pros and cons of
human and automatic mapping and how can they complement each other?" By
pointing out the difficulties in specific cases or groups of cases and grouping
the sample into simple and difficult types of mappings, we show the limitations
of current automatic methods and come up with some basic recommendations on
what approach to use when.


title: Magnetic phase diagram in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single crystals

abstract:
  We have systematically measured resistivity, susceptibility and specific heat
under different magnetic fields (H) in Eu$_{1-x}$La$_x$Fe$_2$As$_2$ single
crystals. It is found that a metamagnetic transition from A-type
antiferromagnetism to ferromagnetism occurs at a critical field for magnetic
sublattice of $Eu^{2+}$. The jump of specific heat is suppressed and shifts to
low temperature with increasing H up to the critical value, then shifts to high
temperature with further increasing H. Such behavior supports the metamagnetic
transition. Detailed H-T phase diagrams for x=0 and 0.15 crystals are given,
and possible magnetic structure is proposed. Magnetoresistance measurements
indicate that there exists a strong coupling between local moment of $Eu^{2+}$
and charge in Fe-As layer. These results are very significant to understand the
underlying physics of FeAs superconductors.


title: Rotation-Resolved Spectroscopy of a Very Young Asteroid, (1270) Datura

abstract:
  (1270) Datura is the largest member of a very young asteroid cluster that was
thought to be broken-up 0.45 Myr ago. The light-curve and the rotation-resolved
reflectance spectra (0.6 um - 1.0 um) were observed in order to find "fresh"
surface. Our data show no significant spectral variation along the rotation
phase. The depth of the 0.95 um absorption band, which indicates the degree of
space weathering, was similar to that of an old S-type asteroid. This suggests
that the reflectance spectrum in this wavelength range changes rapidly and
saturates the depth of the 0.95 um absorption in less than 0.45 Myr in the main
belt environment.


title:
Effect of inter-edge Coulomb interactions on transport through a point
  contact in a \nu = 5/2 quantum Hall state

abstract:
  We study transport across a point contact separating two line junctions in a
\nu = 5/2 quantum Hall system. We analyze the effect of inter-edge Coulomb
interactions between the chiral bosonic edge modes of the half-filled Landau
level (assuming a Pfaffian wave function for the half-filled state) and of the
two fully filled Landau levels. In the presence of inter-edge Coulomb
interactions between all the six edges participating in the line junction, the
stable fixed point corresponds to a point contact which is neither fully opaque
nor fully transparent. Remarkably, this fixed point represents a situation
where the half-filled level is fully transmitting, while the two filled levels
are completely backscattered; hence the fixed point Hall conductance is given
by G_H = {1/2} e^2/h. We predict the non-universal temperature power laws by
which the system approaches the stable fixed point from the two unstable fixed
points corresponding to the fully connected case (G_H = {5/2} e^2/h) and the
fully disconnected case (G_H = 0).


title:
Turbulence-driven Polar Winds from T Tauri Stars Energized by
  Magnetospheric Accretion

abstract:
  Pre-main-sequence stars are observed to be surrounded by both accretion flows
and some kind of wind or jet-like outflow. Recent work by Matt and Pudritz has
suggested that if classical T Tauri stars exhibit stellar winds with mass loss
rates about 0.1 times their accretion rates, the wind can carry away enough
angular momentum to keep the stars from being spun up unrealistically by
accretion. This paper presents a preliminary set of theoretical models of
accretion-driven winds from the polar regions of T Tauri stars. These models
are based on recently published self-consistent simulations of the Sun's
coronal heating and wind acceleration. In addition to the convection-driven MHD
turbulence (which dominates in the solar case), we add another source of wave
energy at the photosphere that is driven by the impact of plasma in neighboring
flux tubes undergoing magnetospheric accretion. This added energy, determined
quantitatively from the far-field theory of MHD wave generation, is sufficient
to produce T Tauri-like mass loss rates of at least 0.01 times the accretion
rate. While still about an order of magnitude below the level required for
efficient angular momentum removal, these are the first self-consistent models
of T Tauri winds that agree reasonably well with a range of observational mass
loss constraints. The youngest modeled stellar winds are supported by Alfven
wave pressure, they have low temperatures ("extended chromospheres"), and they
are likely to be unstable to the formation of counterpropagating shocks and
clumps far from the star.


title:
Compact symmetric spaces, triangular factorization, and Cayley
  coordinates

abstract:
  Let U/K represent a connected, compact symmetric space, where theta is an
involution of U that fixes K, phi: U/K to U is the geodesic Cartan embedding,
and G is the complexification of U. We investigate the intersection of phi(U/K)
with the Bruhat decomposition of G corresponding to a theta-stable triangular,
or LDU, factorization of the Lie algebra of G. When g in phi(U/K) is generic,
the corresponding factorization g=ld(g)u is unique, where l in N^-, d(g) in H,
and u in N^+. In this paper we present an explicit formula for d in Cayley
coordinates, compute it in several types of symmetric spaces, and use it to
identify representatives of the connected components of the generic part of
phi(U/K). This formula calculates a moment map for a torus action on the
highest dimensional symplectic leaves of the Evens-Lu Poisson structure on U/K.


title: Deterministic Diffusion in Periodic Billiard Models

abstract:
  We investigate statistical properties of several classes of periodic billiard
models which are diffusive. An introductory chapter gives motivation, and then
a review of statistical properties of dynamical systems is given in chapter 2.
In chapter 3, we study the geometry dependence of diffusion coefficients in a
two-parameter 2D periodic Lorentz gas model, including a discussion of how to
estimate them from data. In chapter 4, we study the shape of position and
displacement distributions, which occur in the central limit theorem. We show
that there is an oscillatory fine structure and what its origin is. This allows
us to conjecture a refinement of the central limit theorem in these systems. A
non-Maxwellian velocity distribution is shown to lead to a non-Gaussian limit
distribution. Chapter 5 treats polygonal billiard channels, developing a
picture of when normal and anomalous diffusion occur, the latter being due to
parallel scatterers in the billiard causing a channelling effect. We also
characterize the crossover from normal to anomalous diffusion. In chapter 6, we
extend our methods to a 3D periodic Lorentz gas model, showing that normal
diffusion occurs under certain conditions. In particular, we construct an
explicit finite-horizon model, and we discuss the effect that holes in
configuration space have on the diffusive properties of the system. We finish
with conclusions and directions for future research.


title:
Simulation of Imaging Atmospheric Cherenkov Telescopes with CORSIKA and
  sim_telarray

abstract:
  Imaging Atmospheric Cherenkov Telescopes (IACTs) have resulted in a
breakthrough in very-high energy (VHE) gamma-ray astrophysics. While early IACT
installations faced the problem of detecting any sources at all, current
instruments are able to see many sources, often over more than two orders of
magnitude in energy. As instruments and analysis methods have matured, the
requirements for calibration and modelling of physical and instrumental effects
have increased. In this article, a set of Monte Carlo simulation tools is
described that attempts to include all relevant effects for IACTs in great
detail but aims to achieve this in an efficient and flexible way. These tools
were originally developed for the HEGRA IACT system and later adapted for the
H.E.S.S. experiment. Their inherent flexibility to describe quite arbitrary
IACT systems makes them also an ideal tool for evaluating the potential of
future installations. It is in use for design studies of CTA and other
projects.


title: Ultra-large Rydberg dimers in optical lattices

abstract:
  We investigate the dynamics of Rydberg electrons excited from the ground
state of ultracold atoms trapped in an optical lattice. We first consider a
lattice comprising an array of double-well potentials, where each double well
is occupied by two ultracold atoms. We demonstrate the existence of molecular
states with equilibrium distances of the order of experimentally attainable
inter-well spacings and binding energies of the order of 10^3 GHz. We also
consider the situation whereby ground-state atoms trapped in an optical lattice
are collectively excited to Rydberg levels, such that the charge-density
distributions of neighbouring atoms overlap. We compute the hopping rate and
interaction matrix elements between highly-excited electrons separated by
distances comparable to typical lattice spacings. Such systems have tunable
interaction parameters and a temperature ~10^{-4} times smaller than the Fermi
temperature, making them potentially attractive for the study and simulation of
strongly correlated electronic systems.


title: Explicit multidimensional Ingham--Beurling type estimates

abstract:
  Recently a new proof was given for Beurling's Ingham type theorem on
one-dimensional nonharmonic Fourier series, providing explicit constants. We
improve this result by applying a short elementary method instead of the
previous complex analytical approach. Our proof equally works in the
multidimensional case.


title: Cayley automaton semigroups

abstract:
  In this paper we characterize when a Cayley automaton semigroup is a group,
is trivial, is finite, is free, is a left zero semigroup, or is a right zero
semigroup.


title: Insights into the pi- p -> eta n reaction mechanism

abstract:
  A dynamical coupled-channels formalism is used to investigate the
$\eta-$meson production mechanism on the proton induced by pions, in the total
center-of-mass energy region from threshold up to 2 GeV. We show how and why
studying exclusively total cross section data might turn out to be misleading
in pinning down the reaction mechanism.


title: Markovian evolution of Gaussian states in the semiclassical limit

abstract:
  We derive an approximate Gaussian solution of the Lindblad equation in the
semiclassical limit, given a general Hamiltonian and linear coupling with the
environment. The theory is carried out in the chord representation and
describes the evolved quantum characteristic function, which gives direct
access to the Wigner function and the position representation of the density
operator by Fourier transforms. The propagation is based on a system of
non-linear equations taking place in a double phase space, which coincides with
Heller's theory of unitary evolution of Gaussian wave packets when the
Lindbladian part is zero.


title: Time delay of light signals in an energy-dependent spacetime metric

abstract:
  In this note we review the problem of time delay of photons propagating in a
spacetime with a metric that explicitly depends on the energy of the particles
(Gravity-Rainbow approach). We show that corrections due to this approach --
which is closely related to DSR proposal -- produce for small redshifts
($z<<1$) smaller time delays than in the generic Lorentz Invariance Violating
case.


title:
Squeezing the limit: Quantum benchmarks for the teleportation and
  storage of squeezed states

abstract:
  We derive fidelity benchmarks for the quantum storage and teleportation of
squeezed states of continuous variable systems, for input ensembles where the
degree of squeezing $s$ is fixed, no information about its orientation in phase
space is given, and the distribution of phase space displacements is a
Gaussian. In the limit where the latter becomes flat, we prove analytically
that the maximal classical achievable fidelity (which is 1/2 without squeezing,
for $s=1$) is given by $\sqrt{s}/(1+s)$, vanishing when the degree of squeezing
diverges. For mixed states, as well as for general distributions of
displacements, we reduce the determination of the benchmarks to the solution of
a finite-dimensional semidefinite program, which yields accurate, certifiable
bounds thanks to a rigorous analysis of the truncation error. This approach may
be easily adapted to more general ensembles of input states.


title:
State Transfer in Highly Connected Networks and a Quantum Babinet
  Principle

abstract:
  The transfer of a quantum state between distant nodes in two-dimensional
networks, is considered. The fidelity of state transfer is calculated as a
function of the number of interactions in networks that are described by
regular graphs. It is shown that perfect state transfer is achieved in a
network of size N, whose structure is that of a N/2-cross polytope graph, if N
is a multiple of 4. The result is reminiscent of the Babinet principle of
classical optics. A quantum Babinet principle is derived, which allows for the
identification of complementary graphs leading to the same fidelity of state
transfer, in analogy with complementary screens providing identical diffraction
patterns.


title: Modeling electrostatic and quantum detection of molecules

abstract:
  We describe two different modes for electronically detecting an adsorbed
molecule using a nanoscale transistor. The attachment of an ionic molecular
target shifts the threshold voltage through modulation of the depletion layer
electrostatics. A stronger bonding between the molecule and the channel,
involving actual overlap of their quantum mechanical wavefunctions, leads to
scattering by the molecular traps that creates characteristic fingerprints when
scanned with a backgate. We describe a theoretical approach to model these
transport characteristics.


title:
Introduction to the BRS Cohomology of the Massless Wess Zumino Model:
  Cybersusy II

abstract:
  This paper is the second paper in a series of four papers that introduce
cybersusy, which is a new method for analyzing supersymmetry breaking in the
standard supersymmetric model (SSM). The first paper was a summary of the
results and the three next papers set out the details. In this second paper, we
derive the full BRS operator and action for the general massless Wess-Zumino
chiral supersymmetry action. This includes the source terms which bring in the
equations of motion. The auxiliary field is integrated, which removes manifest
supersymmetry, but which allows the Legendre transform to operate correctly to
define one-particle-irreducible vertices from the connected Green's functions.
Then some special terms in the BRS cohomology are described, together with the
constraint equations that they must satisfy. These `simple dotspinors' are
generated by a `fundamental dotspinor', which is constructed partly from the
Zinn sources. The equations of motion play a very important role in the
cohomology for this theory. These dotspinors play an interesting role in the
BRS cohomology of the standard model, which is the subject of the third paper
in the series.


title: Traveling wave solutions of nonlinear partial differential equations

abstract:
  We propose a simple algebraic method for generating classes of traveling wave
solutions for a variety of partial differential equations of current interest
in nonlinear science. This procedure applies equally well to equations which
may or may not be integrable. We illustrate the method with two distinct
classes of models, one with solutions including compactons in a class of models
inspired by the Rosenau-Hyman, Rosenau-Pikovsky and Rosenau-Hyman-Staley
equations, and the other with solutions including peakons in a system which
generalizes the Camassa-Holm, Degasperis-Procesi and Dullin-Gotwald-Holm
equations. In both cases, we obtain new classes of solutions not studied
before.


title:
Uniform bounds for point cohomology of $\ell^1({\mathbb Z}_+)$ and
  related algebras

abstract:
  It is well-known that the point cohomology of the convolution algebra
$\ell^1({\mathbb Z}_+)$ vanishes in degrees 2 and above. We sharpen this result
by obtaining splitting maps whose norms are bounded independently of the choice
of point module. Our construction is a by-product of new estimates on
projectivity constants of maximal ideals in $\ell^1({\mathbb Z}_+)$. Analogous
results are obtained for some other $L^1$-algebras which arise from `rank one'
subsemigroups of ${\mathbb R}_+$.


title: Superefficiency from the Vantage Point of Computability

abstract:
  In 1952 Lucien Le Cam announced his celebrated result that, for regular
univariate statistical models, sets of points of superefficiency have Lebesgue
measure zero. After reviewing the turbulent history of early studies of
superefficiency, I suggest using the notion of computability as a tool for
exploring the phenomenon of superefficiency. It turns out that only computable
parameter points can be points of superefficiency for computable estimators.
This algorithmic version of Le Cam's result implies, in particular, that sets
of points of superefficiency not only have Lebesgue measure zero but are even
countable.


title:
Deducing the multidimensional Szemeredi Theorem from an infinitary
  removal lemma

abstract:
  We offer a new proof of the Furstenberg-Katznelson multiple recurrence
theorem for several commuting probability-preserving transformations T_1, T_2,
>..., T_d: \bbZ\curvearrowright (X,\S,\mu), and so, via the Furstenberg
correspondence principle introduced in, a new proof of the multi-dimensional
Szemeredi Theorem. We bypass the careful manipulation of certain towers of
factors of a probability-preserving system that underlies the
Furstenberg-Katznelson analysis, instead modifying an approach recently
developed for the study of convergence of nonconventional ergodic averages to
pass to a large extension of our original system in which this analysis greatly
simplifies. The proof is then completed using an adaptation of arguments
developed by Tao for his study of an infinitary analog of the hypergraph
removal lemma. In a sense, this addresses the difficulty, highlighted by Tao,
of establishing a direct connection between his infinitary, probabilistic
approach to the hypergraph removal lemma and the infinitary, ergodic-theoretic
approach to Szemeredi's Theorem set in motion by Furstenberg.


title: On the geometry of a class of invariant measures and a problem of Aldous

abstract:
  In his 1985 survey of notions of exchangeability, Aldous introduced a form of
exchangeability corresponding to the symmetries of the infinite discrete cube,
and asked whether these exchangeable probability measures enjoy a
representation theorem similar to those for exchangeable sequences, arrays and
set-indexed families. In this note we to prove that, whereas the known
representation theorems for different classes of partially exchangeable
probability measure imply that the compact convex set of such measures is a
Bauer simplex (that is, its subset of extreme points is closed), in the case of
cube-exchangeability it is a copy of the Poulsen simplex (in which the extreme
points are dense). This follows from the arguments used by Glasner and Weiss'
for their characterization of property (T) in terms of the geometry of the
simplex of invariant measures for associated generalized Bernoulli actions.
  The emergence of this Poulsen simplex suggests that, if a representation
theorem for these processes is available at all, it must take a very different
form from the case of set-indexed exchangeable families.


title: Descent Construction for Gspin Groups: Main Results and Applications

abstract:
  The purpose of this note is to announce an extension of the descent method of
Ginzburg, Rallis and Soudry to the setting of essentially self dual
representations. This extension of the descent construction provides a
complement to recent work of Asgari and Shahidi on the generic transfer for
general Spin groups as well as to the work of Asgari and Raghuram on
cuspidality of the exterior square lift for representations of GL4. Complete
proofs of the results announced in the present note will appear in our
forthcoming articles.


title: Lagrangian Grassmannian in Infinite Dimension

abstract:
  Given a complex structure $J$ on a real (finite or infinite dimensional)
Hilbert space $H$, we study the geometry of the Lagrangian Grassmannian
$\Lambda(H)$ of $H$, i.e. the set of closed linear subspaces $L\subset H$ such
that $$J(L)=L^\perp.$$ The complex unitary group $U(H_J)$, consisting of the
elements of the orthogonal group of $H$ which are complex linear for the given
complex structure, acts transitively on $\Lambda(H)$ and induces a natural
linear connection in $\Lambda(H)$. It is shown that any pair of Lagrangian
subspaces can be joined by a geodesic of this connection. A Finsler metric can
also be introduced, if one regards subspaces $L$ as projections $p_L$ (=the
orthogonal projection onto $L$) or symmetries $\e_L=2p_L-I$, namely measuring
tangent vectors with the operator norm. We show that for this metric the
Hopf-Rinow theorem is valid in $\Lambda(H)$: a geodesic joining a pair of
Lagrangian subspaces can be chosen to be of minimal length. We extend these
results to the classical Banach-Lie groups of Schatten.