title: Non-Walker Self-Dual Neutral Einstein Four-Manifolds of Petrov Type III

abstract:
  The local structure of the manifolds named in the title is described.
Although curvature homogeneous, they are not, in general, locally homogeneous.
Not all of them are Ricci-flat, which answers an existence question about type
III Jordan-Osserman metrics, raised by Diaz-Ramos, Garcia-Rio and
Vazquez-Lorenzo (2006).


title:
M-brane bound states and the supersymmetry of BPS solutions in the
  Bagger-Lambert theory

abstract:
  We continue our study of BPS equations and supersymmetric configurations in
the Bagger-Lambert theory. The superalgebra allows three different types of
central extensions which correspond to compounds of various M-theory objects:
M2-branes, M5-branes, gravity waves and Kaluza-Klein monopoles which intersect
or have overlaps with the M2-branes whose dynamics is given by the
Bagger-Lambert action. As elementary objects they are all 1/2-BPS, and multiple
intersections of $n$-branes generically break the supersymmetry into $1/2^n$,
as it is well known. But a particular composite of M-branes can preserve from
1/16 up to 3/4 of the original ${\cal N}=8$ supersymmetries as previously
discovered. In this paper we provide the M-theory interpretation for various
BPS equations, and also present explicit solutions to some 1/2-BPS equations.


title:
Lord Rutherford of Nelson, His 1908 Nobel Prize in Chemistry and Why He
  Didn't Get a Second Prize

abstract:
  "I have dealt with many different transformations with various periods of
time, but the quickest that I have met was my own transformation in one moment
from a physicist to a chemist."
  Ernest Rutherford (Nobel Banquet, 1908)
  This article is about how Ernest Rutherford (1871-1937) got the 1908 Nobel
Prize in Chemistry and why he did not get a second Prize for his subsequent
outstanding discoveries in physics, specially the discovery of the atomic
nucleus and the proton. Who were those who nominated him and who did he
nominate for the Nobel Prizes.
  In order to put the Prize issue into its proper context, I will briefly
describe Rutherford's whereabouts.
  Rutherford, an exceptionally gifted scientist who revolutionized chemistry
and physics, was moulded in the finest classical tradition. What were his
opinions on some scientific issues such as Einstein's photon, uncertainty
relations and the future prospects for atomic energy? What would he have said
about the "Theory of Everything"?


title:
Effects of Sample Specific Variations and Fluctuations of Thermal
  Occupancy on Fluctuations of Thermodynamic Quantities

abstract:
  Standard results for the fluctuations of thermodynamic quantities are derived
under the assumption of sampling identical systems that are in different, not
fully equilibrated states. These results apply to fluctuations with time in a
particular macroscopic body and can be traced to the fluctuations of thermal
occupancy. When many identically prepared - but not identical - systems are
studied, mesoscopic fluctuations due to variations from sample to sample
contribute to the fluctuations of thermodynamic quantities. We study the
combined effect of mesoscopic fluctuations and fluctuations of thermal
occupancy. In particular, we evaluate the total particle number and specific
heat fluctuations in a two-dimensional, non-interacting electron gas in
classically integrable and chaotic circumstances.


title: Relativistic Motion in a Constant Electromagnetic Field

abstract:
  For a relativistic charged particle moving in a constant electromagnetic
field, its velocity 4-vector has been well studied. However, despite the fact
that both the electromagnetic field and the equations of motion are purely
real, the resulting 4-velocity is seemingly due to a complex electromagnetic
field. This work shows that this is not due to some complex formalism used
(such as Clifford algebra) but is intrinsically due to the fact that the
$o(3,1)$ Lie algebra of the Lorentz group is equivalent to two commuting
complex $su(2)$ algebras. Expressing the complex $su(2)$ generators in terms of
the boost and rotation operators then naturally introduces a complex
electromagnetic field. This work solves the equation of motion not as a matrix
equation, but as an operator evolution equation in terms of the generators of
the Lorentz group. The factorization of the real evolution operator into two
commuting complex evolution operators then directly gives the time evolution of
the velocity 4-vector without any reference to an intermediate field.


title:
Low-field quantum Hall transport in an electron Fabry-Perot
  interferometer: Determination of constriction filling vs front-gate voltage

abstract:
  We report systematic quantum Hall transport experiments on Fabry-Perot
electron interferometers at ultra-low-temperatures. The GaAs/AlGaAs
heterostructure devices consist of two constrictions defined by etch trenches
in 2D electron layer, enclosing an approximately circular island. Front gates
deposited in etch trenches allow to fine-tune the device for symmetry and to
change the constriction filling, relative to the bulk. The low-field
longitudinal and Hall magnetotransport shows Shubnikov-de Haas oscillations and
integer quantum Hall plateaus. A systematic variation of front-gate voltage
affects the constriction and the island electron density, while the bulk
density remains unaffected. This results in quantized plateaus in longitudinal
resistance, while the Hall resistance is dominated by the low-density,
low-filling constriction. At lower fields, when the quantum Hall plateaus fail
to develop, we observe bulk Shubnikov-de Haas oscillations in series
corresponding to an integer filling of the magnetoelectric subbands in the
constrictions. This indicates that the whole interferometer region is still
quantum-coherent at these lower fields at 10 mK. Analyzing the data within a
Fock-Darwin model, we obtain the constriction electron density as a function of
the front gate bias and, extrapolating to the zero field, the number of
electric subbands (conductance channels) resulting from the electron
confinement in the constrictions.


title: Unitarity Cutting Rules for Hard Processes on Nuclear Targets

abstract:
  Unitarity cutting rules for the multiplicity of cut Pomerons, or topological
cross sections, have been obtained within the framework of nonlinear k_t
factorisation. Proper account for the color coupled channel aspects of the
problem leads to the emergence of two types of cut Pomerons. This is
illustrated on the example of topological cross sections in deep inelastic
scattering on a nucleus.


title:
A two-columns formalism for time-dependent modelling of stellar
  convection. I. Description of the method

abstract:
  Despite all advances in multi-dimensional hydrodynamics, investigations of
stellar evolution and stellar pulsations still depend on one-dimensional
computations. The present work devises an alternative to the mixing length
theory or turbulence models usually adopted for the modelling of convective
transport in such studies. Assuming that the largest convective patterns
generate the majority of convective transport, the convective velocity field is
described using two parallel radial columns to represent up- and downstream
flows. Horizontal exchange in the form of fluid flow and radiation over their
connecting interface couples the two columns and allows a simple circulating
motion. The main parameters of this convective description have a
straightforward geometrical meaning, namely the diameter of the columns
(corresponding to the size of the convective cells) and the ratio of cross
section between up- and downdrafts. For this geometrical setup, the
time-dependent solution of the equations of radiation hydrodynamics is computed
from an implicit scheme which has the advantage of being not affected by the
Courant-Friedrichs-Lewy time step limit. In order to demonstrate the approach,
results for the example of convection zones in Cepheids are presented.


title: Relative distances of Omega Centauri and 47 Tucanae

abstract:
  We present precise optical and near-infrared ground-based photometry of two
Globular Clusters (GCs): Omega Cen and 47 Tuc. These photometric catalogs are
unbiased in the Red Giant Branch (RGB) region close to the tip. We provide new
estimates of the RGB tip (TRGB) magnitudes--m_I(TRGB)=9.84+/-0.05, Omega Cen;
m_I(TRGB)=9.46+/-0.06, 47 Tuc--and use these to determine the relative
distances of the two GCs. We find that distance ratios based on different
calibrations of the TRGB, the RR Lyrae stars and kinematic distances agree with
each other within one sigma. Absolute TRGB and RR Lyrae distance moduli agree
within 0.10--0.15 mag, while absolute kinematic distance moduli are 0.2--0.3
mag smaller. Absolute distances to 47 Tuc based on the
Zero-Age-Horizontal-Branch and on the white dwarf fitting agree within 0.1 mag,
but they are 0.1--0.3 mag smaller than TRGB and RR Lyrae distances.


title:
Frequency analysis of Cepheids in the Large Magellanic Cloud. New types
  of classical Cepheid pulsators

abstract:
  We have performed a detailed systematic search for multiperiodicity in the
Population I Cepheids of the Large Magellanic Cloud. In this process we have
identified for the first time several new types of Cepheid pulsational
behaviour. We have found two triple-mode Cepheids pulsating simultaneously in
the first three radial overtones. In 9% of the first overtone Cepheids we have
detected weak, but well resolved secondary periodicities. They appear either
very close to the primary pulsation frequency or at a much higher frequency
with a characteristic period ratio of 0.60-0.64. In either case, the secondary
periodicities must correspond to nonradial modes of oscillation. This result
presents a major challenge to the theory of stellar pulsations, which predicts
that such modes should not be exited in Cepheid variables. Nonradial modes have
also been found in three of the fundamental/first overtone double-mode
Cepheids, but no such oscillations have been detected in single mode Cepheids
pulsating in the fundamental mode. In 19% of double-mode Cepheids pulsating in
the first two radial overtones (FO/SO type) we have detected a Blazhko-type
periodic modulation of amplitudes and phases. Both modes are modulated with a
common period, which is always longer than 700 days. Variations of the two
amplitudes are anticorrelated and maximum of one amplitude always coincides
with minimum of the other. We have compared observations of modulated FO/SO
Cepheids with predictions of theoretical models of the Blazhko effect, showing
that currently most popular models cannot account for properties of these
stars. We propose that Blazhko effect in FO/SO Cepheids can be explained by a
nonstationary resonant interaction of one of the radial modes with another,
perhaps nonradial, mode of oscillations.


title: Edge Detection, Cosmic Strings and the South Pole Telescope

abstract:
  We develop a method of constraining the cosmic string tension $G\mu$ which
uses the Canny edge detection algorithm as a means of searching CMB temperature
maps for the signature of the Kaiser-Stebbins effect. We test the potential of
this method using high resolution, simulated CMB temperature maps. By modeling
the future output from the South Pole Telescope project (including anticipated
instrumental noise), we find that cosmic strings with $G\mu > 5.5\times10^{-8}$
could be detected.


title:
Inferring the Inclination of a Black Hole Accretion Disk from
  Observations of its Polarized Continuum Radiation

abstract:
  Spin parameters of stellar-mass black holes in X-ray binaries are currently
being estimated by fitting the X-ray continuum spectra of their accretion disk
emission. For this method, it is necessary to know the inclination of the
X-ray-producing inner region of the disk. Since the inner disk is expected to
be oriented perpendicular to the spin axis of the hole, the usual practice is
to assume that the black hole spin is aligned with the orbital angular momentum
vector of the binary, and to estimate the inclination of the latter from
ellipsoidal modulations in the light curve of the secondary star. We show that
the inclination of the disk can be inferred directly if we have both spectral
and polarization information on the disk radiation. The predicted degree of
polarization varies from 0% to 5% as the disk inclination changes from face-on
to edge-on. With current X-ray polarimetric techniques the polarization degree
of a typical bright X-ray binary could be measured to an accuracy of 0.1% by
observing the source for about 10 days. Such a measurement would constrain the
disk inclination to within a degree or two and would significantly improve the
reliability of black hole spin estimates. In addition, it would provide new
information on the tilt between the black hole spin axis and the orbital
rotation axis of the binary, which would constrain any velocity kicks
experienced by stellar-mass black holes during their formation.


title: Bipartite entanglement purification with neutral atoms

abstract:
  We theoretically study bipartite entanglement purification with neutral atoms
via cavity-assistant interaction and linear optical elements. We focus on
entanglement distillation and the recurrence protocol, whose performances under
idealized and realistic conditions are discussed. The implementation of these
purification protocols has been tested with numerical simulations. We analyze
the performance and stability of all required operations and emphasize that all
techniques are feasible with current experimental technology.


title: A Morse theoretic description of string topology

abstract:
  Let M be a closed, oriented, n-dimensional manifold. In this paper we give a
Morse theoretic description of the string topology operations introduced by
Chas and Sullivan, and extended by the first author, Jones, Godin, and others.
We do this by studying maps from surfaces with cylindrical ends to M, such that
on the cylinders, they satisfy the gradient flow equation of a Morse function
on the loop space, LM. We then give Morse theoretic descriptions of related
constructions, such as the Thom and Euler classes of a vector bundle, as well
as the shriek, or unkehr homomorphism.


title: Helicity cascades in rotating turbulence

abstract:
  The effect of helicity (velocity-vorticity correlations) is studied in direct
numerical simulations of rotating turbulence down to Rossby numbers of 0.02.
The results suggest that the presence of net helicity plays an important role
in the dynamics of the flow. In particular, at small Rossby number, the energy
cascades to large scales, as expected, but helicity then can dominate the
cascade to small scales. A phenomenological interpretation in terms of a direct
cascade of helicity slowed down by wave-eddy interactions leads to the
prediction of new inertial indices for the small-scale energy and helicity
spectra.


title: Coniveau 2 complete intersections and effective cones

abstract:
  The goal of this paper is first of all to propose a strategy to attack the
generalized Hodge conjecture for coniveau 2 complete intersections, and
secondly to state a conjecture concerning the cones of effective cycle classes
in intermediate dimensions. Our main results show that the generalized Hodge
conjecture for coniveau 2 complete intersections would follow from a particular
case of this effectiveness conjecture.


title:
$\LE$-diagrams and totally positive bases inside the nonnegative
  Grassmannian

abstract:
  There is a cell decomposition of the nonnegative Grassmannian. For each cell,
totally positive bases(TP-bases) is defined as the minimal set of Pl\"ucker
variables such that all other nonzero Pl\"ucker variables in the cell can be
expressed in those variables in a subtraction-free rational function. This is
the generalization of the TP-bases defined for nonnegative part of $GL_k$
defined in \cite{FZ5}.
  For each cell, we have a $\LE$-diagram and a natural way to label the dots
inside the diagram with Pl\"ucker variables. Those set of Pl\"ucker variables
form a TP-bases of the cell. Using mutations coming from 3-term Pl\"ucker
relation, we conjecture that they can be mutated to a special set of Pl\"ucker
variable $\S$. All other nonzero Pl\"ucker variables in the cell will be
expressed as a subtraction-free Laurent polynomial in variables of $\S$. We
define TP-diagrams to express the transformation procedure in terms of moves on
a diagram.
  We will prove the conjecture for certain class of cells called
weakly-connected cells. Then we will study the connection with cluster algebras
through lattice-path-matroid cells.


title:
A Method to Measure cos(2beta) Using Time-Dependent Dalitz Plot Analysis
  of B0 -> D_CP pi+ pi-

abstract:
  We present a feasibility study of a method to measure the cosine of twice the
CKM Unitarity Triangle angle beta using a time-dependent Dalitz plot analysis
of B0 -> D pi+ pi- decays, where the neutral D meson is reconstructed in decays
to CP eigenstates. We show that this method can be used at the B factories to
make a measurement of cos(2beta) that is competitive with, or more precise
than, other techniques using different quark-level transitions, while
sin(2beta) can be measured to an accuracy more precise than any existing
measurement using b -> c ubar d transitions. Furthermore, this technique has
great potential to be employed at LHCb.


title: Sequence-specific size, structure, and stability of tight protein knots

abstract:
  Approximately 1% of the known protein structures display knotted
configurations in their native fold but their function is not understood. It
has been speculated that the entanglement may inhibit mechanical protein
unfolding or transport, e.g., as in cellular threading or translocation
processes through narrow biological pores. Here we investigate tigh peptide
knot (TPK) characteristics in detail by pulling selected 3_1 and 4_1-knotted
peptides using all-atom molecular dynamics computer simulations. We find that
the 3_1 and 4_1-TPK lengths are typically Delta l~4.7 nm and 6.9 nm,
respectively, for a wide range of tensions (F < 1.5 nN), pointing to a pore
diameter of ~2 nm below which a translocated knotted protein might get stuck.
The 4_1-knot length is in agreement with recent AFM pulling experiments.
Detailed TPK characteristics however, may be sequence-specific: we find a
different size and structural behavior in polyglycines, and, strikingly, a
strong hydrogen bonding and water molecule trapping capability of hydrophobic
TPKs due to side chain shielding of the polar TPK core. Water capturing and
release is found to be controlla ble by the tightening force in a few cases.
These mechanisms result into a sequence-specific 'locking' and metastability of
TPKs what might lead to a blocking of knotted peptide transport at designated
sequence-positions. Intriguingly, macroscopic tight 4_1-knot structures are
reproduced microscopically ('figure-of-eight' vs. the 'pretzel') and can be
tuned by sequence in contrast to mathematical predictions. Our findings may
explain a function of knots in native proteins, challenge previous studies on
macromolecular knots, and may find use in bio- and nanotechnology.


title:
Between the Information Economy and Student Recruitment: Present
  Conjuncture and Future Prospects

abstract:
  In university programs and curricula, in general we react to the need to meet
market needs. We respond to market stimulus, or at least try to do so. Consider
now an inverted view. Consider our data and perspectives in university programs
as reflecting and indeed presaging economic trends. In this article I pursue
this line of thinking. I show how various past events fit very well into this
new view. I provide explanation for why some technology trends happened as they
did, and why some current developments are important now.


title:
Simulating the evolution of soot mixing state with a particle-resolved
  aerosol model

abstract:
  The mixing state of soot particles in the atmosphere is of crucial importance
for assessing their climatic impact, since it governs their chemical
reactivity, cloud condensation nuclei activity and radiative properties. To
improve the mixing state representation in models, we present a new approach,
the stochastic particle-resolved model PartMC-MOSAIC, which explicitly resolves
the composition of individual particles in a given population of different
types of aerosol particles. This approach accurately tracks the evolution of
the mixing state of particles due to emission, dilution, condensation and
coagulation. To make this direct stochastic particle-based method practical, we
implemented a new multiscale stochastic coagulation method. With this method we
achieved optimal efficiency for applications when the coagulation kernel is
highly non-uniform, as is the case for many realistic applications.
PartMC-MOSAIC was applied to an idealized urban plume case representative of a
large urban area to simulate the evolution of carbonaceous aerosols of
different types due to coagulation and condensation. For this urban plume
scenario we quantified the individual processes that contribute to the aging of
the aerosol distribution, illustrating the capabilities of our modeling
approach. The results showed for the first time the multidimensional structure
of particle composition, which is usually lost in internally-mixed sectional or
modal aerosol models.


title:
Evolution of the quasi-periodic oscillation frequency in GRO J1655-40 --
  Implications for accretion disk dynamics

abstract:
  Low and intermediate frequency quasi-periodic oscillations (QPOs) are thought
to be due to oscillations of Comptonizing regions or hot blobs embedded in
Keplerian disks. Any movement of these perturbations is expected systematically
to change the QPO frequency. Our goal is to find systems where such a
systematic drifts have been observed. We also try to find the real cause of
such drifts and whether they shed some light on the accretion disk dynamics.
Using archival data of the recent outburst of GRO J1655-40, we report the
presence of such systematic drifts not only during the rising phase from the
25th of February 2005 to the 12th March 2005, when the QPO frequency
monotonically increased from 82mHz to 17.78Hz but also in the decline phase
from the 15th September 2005 to the 5th of October 2005, when the QPO frequency
decreased from 13.14Hz to 34mHz. We fitted the frequency drifts with the
propagatory oscillating shock solution. In the shock-oscillation solution, the
frequency is inversely proportional to the infall time scale from the shock
location. We obtained the shock location and strength through such a fit. The
astonishing smoothness of the variation of the QPO frequency over a period of
weeks directly supports the view that it may due to the drift of an oscillating
shock rather than the movements of a blob inside a differentially rotating
disk.


title: Pressure induced orientational glass phase in molecular para-hydrogen

abstract:
  We propose a theoretical description of possible orientational glass
transition in solid molecular para-hydrogen and ortho-deuterium under pressure
supposing that they are mixtures of J=0 and J=2 states of molecules. The theory
uses the basic concepts and methods of standard spin-glass theory. We expect
our orientational glass to correspond the II' phase of the high pressure
hydrogen phase diagram.


title: A Minimalist Turbulent Boundary Layer Model

abstract:
  We introduce an elementary model of a turbulent boundary layer over a flat
surface, given as a vertical random distribution of spanwise Lamb-Oseen vortex
configurations placed over a non-slip boundary condition line. We are able to
reproduce several important features of realistic flows, such as the viscous
and logarithmic boundary sublayers, and the general behavior of the first
statistical moments (turbulent intensity, skewness and flatness) of the
streamwise velocity fluctuations. As an application, we advance some heuristic
considerations on the boundary layer underlying kinematics that could be
associated with the phenomenon of drag reduction by polymers, finding a
suggestive support from its experimental signatures.


title: Confinement and Chiral Symmetry, a Lattice QCD test of AdS/QCD

abstract:
  We use lattice QCD simulations to test some of the predictions of proposed
AdS/QCD (holographic) duals for QCD. In particular, these duals predict that
the scale of chiral symmetry breaking ($\chi$SB) can be varied independently
from that of confinement, with the proviso that the scale of $\chi$SB cannot be
longer than that of confinement. We simulate lattice QCD with 2 quarks in the
fundamental representation of colour and with additional 4-fermion interactions
(suggested by AdS/QCD), at finite temperatures. For sufficiently strong
4-fermion interactions, the deconfinement and $\chi$SB transitions occur at
different temperatures, the separation depending on the 4-fermion coupling.
This confirms that the scales of confinement and $\chi$SB are, in general,
different.


title:
Aharonov-Casher and spin Hall effects in two-dimensional mesoscopic ring
  structures with strong spin-orbit interaction

abstract:
  We study the quantum interference effects induced by the Aharonov-Casher
phase in asymmetrically confined two-dimensional electron and heavy-hole ring
structures systems taking into account the electrically tunable spin-orbit (SO)
interaction. We have calculated the non-adiabatic transport properties of
charges (heavy-holes and electrons) in two-probe thin ring structures and
compare how the form of the SO coupling of the carries affects it. We show that
both the SO splitting of the bands and the carrier density can be used to
modulate the conductance through the ring. We show that the dependence on
carrier density is due to the backscattering from the leads which shows
pronounce resonances when the Fermi energy is close to the eigenenergy of the
ring. We also calculate the spin Hall conductivity and longitudinal
conductivity in four-probe rings as a function of the carrier density and SO
interaction, demonstrating that for heavy-hole carriers both conductivities are
larger than for electrons. Finally, we investigate the transport properties of
mesoscopic rings with spatially inhomogeneous SO coupling. We show that devices
with inhomogeneous SO interaction exhibit an electrically controlled
spin-flipping mechanism.


title: Reliable Eigenspectra for New Generation Surveys

abstract:
  We present a novel technique to overcome the limitations of the applicability
of Principal Component Analysis to typical real-life data sets, especially
astronomical spectra. Our new approach addresses the issues of outliers,
missing information, large number of dimensions and the vast amount of data by
combining elements of robust statistics and recursive algorithms that provide
improved eigensystem estimates step-by-step. We develop a generic mechanism for
deriving reliable eigenspectra without manual data censoring, while utilising
all the information contained in the observations. We demonstrate the power of
the methodology on the attractive collection of the VIMOS VLT Deep Survey
spectra that manifest most of the challenges today, and highlight the
improvements over previous workarounds, as well as the scalability of our
approach to collections with sizes of the Sloan Digital Sky Survey and beyond.


title:
Accurate Estimation of Solvation Free Energy Using Polynomial Fitting
  Techniques

abstract:
  This report details an approach to improve the accuracy and precision of free
energy difference estimates using thermodynamic integration data (slope of the
free energy with respect to the switching variable lambda) and its application
to calculating solvation free energy. The central idea is to utilize polynomial
fitting schemes to approximate the thermodynamic integration data to improve
the accuracy and precision of the free energy difference estimates. In this
report we introduce polynomial and spline interpolation techniques. Two systems
with analytically solvable relative free energies are used to test the accuracy
and precision of the interpolation approach (Shyu and Ytreberg, J Comput Chem
30: 2297-2304, 2009). We also use both interpolation and extrapolation methods
to determine a small molecule salvation free energy. Our simulations show that,
using such polynomial techniques and non-equidistant lambda values, the
solvation free energy can be estimated with high accuracy without using
soft-core scaling and separate simulations for Lennard-Jones and partial
charges. The results from our study suggest these polynomial techniques,
especially with use of non-equidistant lambda values, improve the accuracy and
precision for dF estimates without demanding additional simulations. To allow
researchers to immediately utilize these methods, free software and
documentation is provided via http://www.phys.uidaho.edu/ytreberg/software


title: The Reddest DR3 SDSS/XMM Quasars

abstract:
  We have cross-correlated the SDSS DR3 Schneider et al. (2005) quasar catalog
with the XMM-Newton archive. Color and redshift selections (g - r > 0.5 and 0.9
z < 2.1) result in a sample of 17 red, moderate redshift quasars. The redshift
selection minimizes possible contamination due to host galaxy emission and
Lyalpha forest absorption. Both optical and X-ray information are required to
distinguish between the two likely remaining causes of the red colors: 1)
dust-reddening and 2) an intrinsically red continuum. We find that 7 of 17
quasars can be classified as probable `intrinsically red' objects. These 7
quasars have unusually broad MgII emission lines (<FWHM>=10,500 km s^{-1}),
moderately flat, but unabsorbed X-ray spectra <Gamma>=1.66+/-0.08), and low
accretion rates (mdot/mdot_{Edd}} ~ 0.01). We suggest low accretion rates as a
possible physical explanation for quasars with intrinsically red optical
continua. We find that 8 of 17 quasars can be classified as dust-reddened.
Three of these have upper-limits on the absorption column from X-ray spectral
fits of N_H = 3-13 x 10^{22} cm^2, while the other five quasars must be
absorbed by at least N_H = 10^{23} cm^2 in order to be consistent with a
comparably selected alpha_{ox}-l_{uv} distribution. Two objects in the sample
are unclassified.


title: On the role of metaphor in information visualization

abstract:
  The concept of metaphor, in particular graphical (or visual) metaphor, is
central to the field of information visualization. Information graphics and
interactive information visualization systems employ a variety of metaphorical
devices to make abstract, complex, voluminous, or otherwise
difficult-to-comprehend information understandable in graphical terms. This
paper explores the use of metaphor in information visualization, advancing the
theory previously argued by Johnson, Lakoff, Tversky et al. that many
information graphics are metaphorically understood in terms of cognitively
entrenched spatial patterns known as image schemas. These patterns serve to
structure and constrain abstract reasoning processes via metaphorical
projection operations that are grounded in everyday perceptual experiences with
phenomena such as containment, movement, and force dynamics. Building on
previous research, I argue that information graphics promote comprehension of
their target information through the use of graphical patterns that invoke
these preexisting schematic structures. I further theorize that the degree of
structural alignment of a particular graphic with one or more corresponding
image schemas accounts for its perceived degree of intuitiveness. Accordingly,
image schema theory can provide a powerful explanatory and predictive framework
for visualization research. I review relevant theories of analogy and metaphor,
and discuss the image schematic properties of several common types of
information graphic. I conclude with the proposal that the inventory of image
schemas culled from linguistic studies can serve as the basis for an inventory
of design elements suitable for developing intuitive and effective new
information visualization techniques.


title: Searches for Non-Standard-Model Higgs Bosons at the Tevatron

abstract:
  The Standard Model of particle physics has a number of asymmetries suggestive
of a more fundamental theory, where the symmetries are restored. If the
symmetry breaking scale is the electroweak scale, new Higgs bosons beyond that
of the Standard Model could be observed at the Tevatron. Recent Tevatron
searches have set the most stringent limits on new Higgs bosons in a variety of
models.


title: Can proper motions of dark-matter subhalos be detected?

abstract:
  One of the goals of NASA's Fermi Gamma-ray Space Telescope (formerly GLAST)
will be detection of gamma rays from dark-matter annihilation in the Galactic
halo. Theoretical arguments suggest that dark matter may be bound into subhalos
with masses as small as 10^{-4}--10^2 Earth mass. If so, it may be possible to
detect individual subhalos as point sources in the Fermi Telescope. It has
further been argued that some of these point sources may exhibit proper
motions. Here we show that upper limits to the diffuse gamma-ray background
constrain the number of subhalos close enough to exhibit proper motions to be
less than one.


title: Cassiopeia A: dust factory revealed via submillimetre polarimetry

abstract:
  If Type-II supernovae - the evolutionary end points of short-lived, massive
stars - produce a significant quantity of dust (>0.1 M_sun) then they can
explain the rest-frame far-infrared emission seen in galaxies and quasars in
the first Gyr of the Universe. Submillimetre observations of the Galactic
supernova remnant, Cas A, provided the first observational evidence for the
formation of significant quantities of dust in Type-II supernovae. In this
paper we present new data which show that the submm emission from Cas A is
polarised at a level significantly higher than that of its synchrotron
emission. The orientation is consistent with that of the magnetic field in Cas
A, implying that the polarised submm emission is associated with the remnant.
No known mechanism would vary the synchrotron polarisation in this way and so
we attribute the excess polarised submm flux to cold dust within the remnant,
providing fresh evidence that cosmic dust can form rapidly. This is supported
by the presence of both polarised and unpolarised dust emission in the north of
the remnant, where there is no contamination from foreground molecular clouds.
The inferred dust polarisation fraction is unprecedented (f_pol ~ 30%) which,
coupled with the brief timescale available for grain alignment (<300 yr),
suggests that supernova dust differs from that seen in other Galactic sources
(where f_pol=2-7%), or that a highly efficient grain alignment process must
operate in the environment of a supernova remnant.


title: Modeling of Polymer Clay Nanocomposite for a Multiscale Approach

abstract:
  The mechanical property enhancement of polymer reinforced with nano-thin clay
platelets (of high aspect ratio) is associated with a high polymer-filler
interfacial area per unit volume. The ideal case of fully separated
(exfoliated) platelets is generally difficult to achieve in practice: a typical
nanocomposite also contains multilayer stacks of intercalated platelets. Here
we use numerical modelling to investigate how the platelet properties affect
the overall mechanical properties. The configuration of platelets is modelled
using a statistical interpretation of the Representative Volume Element (RVE)
approach, in which an ensemble of "sample" heterogeneous material is generated
(with periodic boundary conditions). A simple Monte Carlo algorithm is used to
place non-intersecting platelets in the RVE according to a specified set of
statistical distributions. The effective stiffness of the platelet-matrix
system is determined by measuring the stress (using standard Finite Element
analysis) produced as a result of applying a small deformation to the
boundaries, and averaging over the entire statistical ensemble. In this work we
determine the way in which the platelet properties (curvature, filling
fraction, stiffness, aspect ratio) and the number of layers in the stack affect
the overall stiffness enhancement of the nanocomposite. Thus, we bridge the gap
between behaviour on the macroscopic scale with that on the scale of the
nano-reinforcement, forming part of a multi-scale modelling framework.


title: Rainbow statistics

abstract:
  Non-commutative quantum field theories and their global quantum group
symmetries provide an intriguing attempt to go beyond the realm of standard
local quantum field theory. A common feature of these models is that the
quantum group symmetry of their Hilbert spaces induces additional structure in
the multiparticle states which reflects a non-trivial momentum-dependent
statistics. We investigate the properties of this "rainbow statistics" in the
particular context of $\kappa$-quantum fields and discuss the
analogies/differences with models with twisted statistics.


title: E+A and Companion Galaxies - I : A Catalogue and Statistics

abstract:
  Based on our intensive spectroscopic campaign with the GoldCam spectrograph
on the Kitt Peak National Observatory (KPNO) 2.1-m telescope, we have
constructed the first catalogue of E+A galaxies with spectroscopic companion
galaxies, and investigated a probability that an E+A galaxy have close
companion galaxies. We selected 660 E+A galaxies with $4.0{\rm \AA} < {\rm
H}\delta {\rm EW}$ at a redshift of $<0.167$ from the Data Release 5 of the
Sloan Digital Sky Survey (SDSS). We selected their companion candidates from
the SDSS imaging data, and classified them into true companions,
fore/background galaxies and companion candidates using the SDSS and our KPNO
spectra. We observed 26 companion candidates of E+A galaxies at the KPNO to
measure their redshifts. Their spectra showed that 17 targets are true
companion galaxies. The number of spectroscopically-confirmed E+A's companions
are now 34. This becomes the first catalogue of E+A galaxies with spectroscopic
companion systems. We found that E+A galaxies have an 54% larger probability of
having companion galaxies (7.88%) compared to the comparison sample of normal
galaxies (5.12%). A statistical test shows the probabilities are different with
99.7% significance. Our results based on spectroscopy tightens the connection
between the dynamical merger/interaction and the origin of E+A galaxies.


title:
Spatially-Resolved Medium Resolution Spectroscopy of an Interacting E+A
  (post-starburst) System with the Subaru telescope

abstract:
  We have performed a spatially-resolved medium resolution long-slit
spectroscopy of a nearby E+A (post-starburst) galaxy system,
SDSSJ161330.18+510335.5. This E+A galaxy has an obvious companion galaxy 14kpc
in front with the velocity difference of 61.8 km/s. Both galaxies have
obviously disturbed morphology We have found that H$\delta$ equivalent width
(EW) of the E+A galaxy is greater than 7\AA galaxy wide (8.5 kpc). The E+A
galaxy have a weak [OIII] emission (EW$\sim$1\AA) by $\sim$2.6 kpc offset from
the peak of the Balmer absorption lines. We detected a rotational velocity in
the companion galaxy of $>$175km/s. The progenitor of the companion may have
been a rotationally-supported, but yet passive S0 galaxy. The age of the E+A
galaxy after quenching the star formation is estimated to be 100-500 Myr, with
its centre having slightly younger stellar population. These findings are
inconsistent with a simple picture where the dynamical interaction creates
infall of the gas reservoir that causes the central starburst/post-starburst.
Instead, our results present an important example where the galaxy-galaxy
interaction can trigger a galaxy-wide post-starburst phenomena.


title: Color Screening by Pions

abstract:
  Lattice QCD is used to calculate the potential between a static quark and
anti-quark in the presence of a finite density of pi^+'s. Correlation functions
of multiple pi^+'s are used in conjunction with Wilson-loop correlators to
determine the difference between the Q\overline{Q}-potential in free-space and
in the presence of a pion condensate. The modifications to the potential are
found to have significant dependence on the Q\overline{Q} separation over the
range r < 1 fm explored in this work. Our results are consistent with the
pion-condensate behaving as a (nonlinear) chromo-dielectric.


title: Spatial Distributions of Young Stars

abstract:
  We analyze the spatial distributions of young stars in Taurus-Auriga and
Upper Sco as determined from the two-point correlation function (i.e. the mean
surface density of neighbors). The corresponding power-law fits allow us to
determine the fractal dimensions of each association's spatial distribution,
measure the stellar velocity dispersions, and distinguish between the bound
binary population and chance alignments of members. We find that the fractal
dimension of Taurus is D~1.05, consistent with its filamentary structure. The
fractal dimension of Upper Sco may be even shallower (D~0.7), but this fit is
uncertain due to the limited area and possible spatially-variable
incompleteness. We also find that random stellar motions have erased all
primordial structure on scales of <0.07 degrees in Taurus and <1.7 degrees in
Upper Sco; given ages of ~1 Myr and ~5 Myr, the corresponding internal velocity
dispersions are ~0.2 km/s and ~1.0 km/s, respectively. Finally, we find that
binaries can be distinguished from chance alignments at separations of <120"
(17000 AU) in Taurus and 75" (11000 AU) in Upper Sco. The binary populations in
these associations that we previously studied, spanning separations of 3-30",
are dominated by binary systems. However, the few lowest-mass pairs (M_prim <
0.3 M_sun) might be chance alignments.


title:
A blueprint for detecting supersymmetric dark matter in the Galactic
  halo

abstract:
  Dark matter is the dominant form of matter in the universe, but its nature is
unknown. It is plausibly an elementary particle, perhaps the lightest
supersymmetric partner of known particle species. In this case, annihilation of
dark matter in the halo of the Milky Way should produce gamma-rays at a level
which may soon be observable. Previous work has argued that the annihilation
signal will be dominated by emission from very small clumps (perhaps smaller
even than the Earth) which would be most easily detected where they cluster
together in the dark matter halos of dwarf satellite galaxies. Here we show,
using the largest ever simulation of the formation of a galactic halo, that
such small-scale structure will, in fact, have a negligible impact on dark
matter detectability. Rather, the dominant and likely most easily detectable
signal will be produced by diffuse dark matter in the main halo of the Milky
Way. If the main halo is strongly detected, then small dark matter clumps
should also be visible, but may well contain no stars, thereby confirming a key
prediction of the Cold Dark Matter (CDM) model.


title: Visual orbit of GJ 164 AB

abstract:
  We report seven successful observations of the astrometric binary GJ 164 AB
system with aperture masking interferometry. The companion, with a near
infrared contrast of 5:1 was detected beyond the formal diffraction limit.
Combined with astrometric observations from the literature, these observations
fix the parallax of the system, and allow a model-independent mass
determination of both components. We find the mass of GJ 164B to be $ 0.086 \pm
0.007 M_{\sun}$. An infrared spectroscopic study of a sample of M-Dwarfs
outlines a method for calibrating metallicity of M-Dwarfs. Results from the
newly commissionned TripleSpec spectrograph reveal that the GJ 164 system is at
least of Solar metallicity. Models are not consistent with color and mass,
requiring a very young age to accommodate a secondary too luminous, a scenario
ruled out by the kinematics.


title:
Outliers from the Mass--Metallicity Relation II: A Sample of Massive
  Metal-Poor Galaxies from SDSS

abstract:
  We present a sample of 42 high-mass low-metallicity outliers from the
mass--metallicity relation of star-forming galaxies. These galaxies have
stellar masses that span log(M_*/M_sun) ~9.4 to 11.1 and are offset from the
mass--metallicity relation by -0.3 to -0.85 dex in 12+log(O/H). In general,
they are extremely blue, have high star formation rates for their masses, and
are morphologically disturbed. Tidal interactions are expected to induce
large-scale gas inflow to the galaxies' central regions, and we find that these
galaxies' gas-phase oxygen abundances are consistent with large quantities of
low-metallicity gas from large galactocentric radii diluting the central
metal-rich gas. We conclude with implications for deducing gas-phase
metallicities of individual galaxies based solely on their luminosities,
specifically in the case of long gamma-ray burst host galaxies.


title:
iVINE - Ionization in the parallel tree/SPH code VINE: First results on
  the observed age-spread around O-stars

abstract:
  We present a three-dimensional, fully parallelized, efficient implementation
of ionizing UV radiation for smoothed particle hydrodynamics (SPH) including
self-gravity. Our method is based on the SPH/tree code VINE. We therefore call
it iVINE (for Ionization + VINE). This approach allows detailed high-resolution
studies of the effects of ionizing radiation from e.g. young massive stars on
their turbulent parental molecular clouds. In this paper we describe the
concept and the numerical implementation of the radiative transfer for a
plain-parallel geometry and we discuss several test cases demonstrating the
efficiency and accuracy of the new method. As a first application, we study the
radiatively driven implosion of marginally stable molecular clouds at various
distances of a strong UV source and show that they are driven into
gravitational collapse. The resulting cores are very compact and dense exactly
as it is observed in clustered environments. Our simulations indicate that the
time of triggered collapse depends on the distance of the core from the UV
source. Clouds closer to the source collapse several $10^5$ years earlier than
more distant clouds. This effect can explain the observed age spread in OB
associations where stars closer to the source are found to be younger. We
discuss possible uncertainties in the observational derivation of shock front
velocities due to early stripping of proto-stellar envelopes by ionizing
radiation.


title: The Aquarius Project: the subhalos of galactic halos

abstract:
  We have performed the largest ever particle simulation of a Milky Way-sized
dark matter halo, and present the most comprehensive convergence study for an
individual dark matter halo carried out thus far. We have also simulated a
sample of 6 ultra-highly resolved Milky-way sized halos, allowing us to
estimate the halo-to-halo scatter in substructure statistics. In our largest
simulation, we resolve nearly 300,000 gravitationally bound subhalos within the
virialized region of the halo. Simulations of the same object differing in mass
resolution by factors up to 1800 accurately reproduce the largest subhalos with
the same mass, maximum circular velocity and position, and yield good
convergence for the abundance and internal properties of dark matter
substructures. We detect up to four generations of subhalos within subhalos,
but contrary to recent claims, we find less substructure in subhalos than in
the main halo when regions of equal mean overdensity are compared. The overall
substructure mass fraction is much lower in subhalos than in the main halo.
Extrapolating the main halo's subhalo mass spectrum down to an Earth mass, we
predict the mass fraction in substructure to be well below 3% within 100 kpc,
and to be below 0.1% within the Solar Circle. The inner density profiles of
subhalos show no sign of converging to a fixed asymptotic slope and are well
fit by gently curving profiles of Einasto form. The mean concentrations of
isolated halos are accurately described by the fitting formula of Neto et al.
down to maximum circular velocities of 1.5 km/s, an extrapolation over some 5
orders of magnitude in mass. However, at equal maximum circular velocity,
subhalos are more concentrated than field halos, with a characteristic density
that is typically ~2.6 times larger and increases towards the halo centre.


title:
Late Ordovician geographic patterns of extinction compared with
  simulations of astrophysical ionizing radiation damage

abstract:
  Based on the intensity and rates of various kinds of intense ionizing
radiation events such as supernovae and gamma-ray bursts, it is likely that the
Earth has been subjected to one or extinction level events during the
Phanerozoic. These induce changes in atmospheric chemistry so that the level of
Solar ultraviolet-B radiation reaching the surface and near-surface waters may
be doubled for up to a decade. This UVB level is known from experiment to be
more than enough to kill off many kinds of organisms, particularly
phytoplankton. It could easily induce a crash of the photosynthetic-based food
chain in the oceans. Regularities in the latitudinal distribution of damage are
apparent in simulations of the atmospheric changes. We previously proposed that
the late Ordovician extinction is a plausible candidate for a contribution from
an ionizing radiation event, based on environmental selectivity in trilobites.
To test a null hypothesis based on this proposal, we confront latitudinal
differential extinction rates predicted from the simulations with data from a
published analysis of latitudinal gradients in the Ordovician extinction. The
pattern of UVB damage always shows a strong maximum at some latitude, with
substantially lower intensity to the north and south of this maximum. We find
that the pattern of damage predicted from our simulations is consistent with
the data assuming a burst approximately over the South Pole, and no further
north than -75 degrees. We predict that any land mass (such as parts of north
China, Laurentia, and New Guinea) which then lay north of the equator should be
a refuge from UVB effects, and show a different pattern of extinction in the
first strike of the end-Ordovician extinction, if induced by such a radiation
event.

categories: astro-ph physics.ao-ph physics.bio-ph physics.geo-ph q-bio.PE


title: Low-frequency excitation of double quantum dots

abstract:
  We address theoretically adiabatic regime of charge transport for a model of
two tunnel-coupled quantum dots connected in series. The energy levels of the
two dots are harmonically modulated by an external potential with a constant
phase shift between the two. Motivated by recent experiments with
surface-acoustic-wave excitation, we consider two situations: (a) pure pumping
in the absence of external voltage (also at finite temperature), and (b)
adiabatic modulation of the current driven by large external bias. In both
cases we derive results consistent with published experimental data. For the
case (b) we explicitly derive the adiabatic limit of Tien-Gordon formula for
photon-assisted tunneling and compare it to the outcome of simple conductance
modulation. A tutorial for adiabatic pumping current calculations with the
Green function formalism is included.


title: The dynamical structure of dark matter halos with universal properties

abstract:
  $N$-body simulations have unveiled several apparently universal properties of
dark matter halos, including a cusped density profile, a power-law pseudo
phase-space density $\rho/\sigma_r^3$, and a linear $\beta-\gamma$ relation
between the density slope and the velocity anisotropy. We present a family of
self-consistent phase-space distribution functions $F(E,L)$, based on the
Dehnen-McLaughlin Jeans models, that incorporate these universal properties
very accurately. These distribution functions, derived using a quadratic
programming technique, are analytical, positive and smooth over the entire
phase space and are able to generate four-parameter velocity anisotropy
profiles $\beta(r)$ with arbitrary asymptotic values $\beta_0$ and
$\beta_\infty$. We discuss the orbital structure of six radially anisotropic
systems in detail and argue that, apart from its use for generating initial
conditions for $N$-body studies, our dynamical modeling provides a valuable
complementary approach to understand the processes involved in the formation of
dark matter halos.


title: The Seventeen Elements of Pythagorean Triangles

abstract:
  This is an exhaustive study of the seventeen elements of Pythagorean
triangles, from the point of view of when such an element is an irrational
number, a rational number, or an integer. For each of these 17 elements,precice
conditions for their integrality,rationality, or irrationality; are given.
These 17 elements are:The radius of the incircle, the radius of the
circumscribed circle,the three radii of the three exterior circles tangential
to the three lines containing the triangles'sides, the lengths of the three
heights, the lenghts of the three internal angle bisectors, the lengthe of the
three external angle bisectors, and the lengths of the three medians.


title: Thermal Emission from Gamma-Ray Bursts

abstract:
  In recent years, there are increasing evidence for a thermal emission
component that accompanies the overall non-thermal spectra of the prompt
emission phase in GRBs. Both the temperature and flux of the thermal emission
show a well defined temporal behavior, a broken power law in time. The
temperature is nearly constant during the first few seconds, afterwards it
decays with power law index alpha ~0.7. The thermal flux also decays at late
times as a power law with index beta ~2.1. This behavior is very ubiquitous,
and was observed in a sample currently containing 32 BATSE bursts. These
results are naturally explained by considering emission from the photosphere.
The photosphere of a relativistically expanding plasma wind strongly depends on
the angle to the line of sight, theta. As a result, thermal emission can be
seen after tens of seconds. By introducing probability density function
P(r,theta) of a thermal photon to escape the plasma at radius r and angle
theta, the late time behavior of the flux can be reproduced analytically.
During the propagation below the photosphere, thermal photons lose energy as a
result of the slight misalignment of the scattering electrons velocity vectors,
which leads to photon comoving energy decay epsilon'(r)~r^{-2/3}. This in turn
can explain the decay of the temperature observed at late times. Finally, I
show that understanding the thermal emission is essential in understanding the
high energy, non-thermal spectra. Moreover, thermal emission can be used to
directly measure the Lorentz factor of the flow and the initial jet radius.


title: The holomorphic Gauss Parametrization

abstract:
  We give a local parametric description of all holomorphic hypersurfaces in
complex Euclidean and projective spaces with constant index of relative
nullity, together with applications. This is a complex analogue to the
parametrization for real hypersurfaces in Euclidean space known as the Gauss
parametrization.


title: Birational rigidity of Fano varieties and field extensions

abstract:
  The aim of this note is to settle some foundational questions about the
behavior of birational rigidity in extensions of algebraically closed fields.


title: Stability for time-dependent inverse transport

abstract:
  This paper concerns the reconstruction of the absorption and scattering
parameters in a time-dependent linear transport equation from full knowledge of
the albedo operator at the boundary of a bounded domain of interest. We present
optimal stability results on the reconstruction of the absorption and
scattering parameters for a given error in the measured albedo operator.


title: Traversable wormholes: Some simple examples

abstract:
  Building on the work of Morris, Thorne, and Yurtsever, some particularly
simple examples of traversable wormholes are exhibited. These examples are
notable both because the analysis is not limited to spherically symmetric
cases, and because it is possible to in some sense minimize the use of exotic
matter. In particular, it is possible for a traveller to traverse such a
wormhole without passing through a region of exotic matter. As in previous
analyses, the weak energy condition is violated in these traversable wormholes.


title:
Reduced Complexity Demodulation and Equalization Scheme for Differential
  Impulse Radio UWB Systems with ISI

abstract:
  In this paper, we consider the demodulation and equalization problem of
differential Impulse Radio (IR) Ultra-WideBand (UWB) Systems with
Inter-Symbol-Interference (ISI). The differential IR UWB systems have been
extensively discussed recently. The advantage of differential IR UWB systems
include simple receiver frontend structure. One challenge in the demodulation
and equalization of such systems with ISI is that the systems have a rather
complex model. The input and output signals of the systems follow a
second-order Volterra model. Furthermore, the noise at the output is data
dependent. In this paper, we propose a reduced-complexity joint demodulation
and equalization algorithm. The algorithm is based on reformulating the nearest
neighborhood decoding problem into a mixed quadratic programming and utilizing
a semi-definite relaxation. The numerical results show that the proposed
demodulation and equalization algorithm has low computational complexity, and
at the same time, has almost the same error probability performance compared
with the maximal likelihood decoding algorithm.


title:
The Schroedinger equation as the time evolution of a deterministic and
  reversible process

abstract:
  In this paper we derive the Schroedinger equation by assuming it describes
the time evolution of a deterministic and reversible process that leaves at
each moment in time a different observable well defined; that is, it allows an
accurate prediction for it. We also derive an expression for the well defined
observable and apply this expression to the cases of spin precession and a free
particle.


title:
Modeling the Unconventional Superconducting Properties of Expanded
  A$_3$C$_{60}$ Fullerides

abstract:
  The trivalent alkali fullerides A$_3$C$_{60}$, where C$_{60}$ are a well
established family of molecular superconductors. The electron pairing has
s-wave symmetry and is due to standard electron-phonon coupling, in particular
by Jahn-Teller intramolecular C$_{60}$ vibrations.
  A source of renewed interest in these systems are indications of strong
electron-electron repulsion, which emerges especially in compounds where the
C$_{60}$-C$_{60}$ distance is expanded. In several compounds after an initial
increases T$_c$, further expansions leads to a decline of superconductivity and
its eventual disappearance in favor of a Mott insulating state
  We theoretically study a three-orbital Hubbard model including the
phonon-mediated interaction using Dynamical Mean-Field Theory, which is
particularly suitable due to the local nature of all the interactions. We
studied the system as a function of the ratio of intra-molecular repulsion $U$
over the electron bandwidth $W$, the increase of $U/W$ representing the main
effect of lattice expansion. The phase diagram is close to that of actual
materials, with a dome-shaped superconducting region preceding the Mott
transition. Unconventional properties predicted by this model include: (i) a
pseudogap in the normal phase; (ii) a gain of kinetic energy and of d.c.
conductivity at the onset of superconductivity; (iii) regular spin
susceptibility and specific heat despite strong correlations; (iv) the
emergence of more than one energy scale governing the renormalized single
particle dispersion. These predictions, if confirmed, would establish
fullerides, especially the expanded ones, as members of the wider family of
strongly correlated superconductors.


title: Nonabelian harmonic analysis and functional equations on compact groups

abstract:
  Making use of nonabelian harmonic analysis and representation theory, we
solve the functional equation
$$f_1(xy)+f_2(yx)+f_3(xy^{-1})+f_4(y^{-1}x)=f_5(x)f_6(y)$$ on arbitrary compact
groups. The structure of its general solution is completely described.
Consequently, several special cases of the above equation, in particular, the
Wilson equation and the d'Alembert long equation, are solved on compact groups.


title: Five New High-Redshift Quasar Lenses from the Sloan Digital Sky Survey

abstract:
  We report the discovery of five gravitationally lensed quasars from the Sloan
Digital Sky Survey (SDSS). All five systems are selected as two-image lensed
quasar candidates from a sample of high-redshift (z>2.2) SDSS quasars. We
confirmed their lensing nature with additional imaging and spectroscopic
observations. The new systems are SDSS J0819+5356 (source redshift z_s=2.237,
lens redshift z_l=0.294, and image separation \theta=4.04"), SDSS J1254+2235
(z_s=3.626, \theta=1.56"), SDSS J1258+1657 (z_s=2.702, \theta=1.28"), SDSS
J1339+1310 (z_s=2.243, \theta=1.69"), and SDSS J1400+3134 (z_s=3.317,
\theta=1.74"). We estimate the lens redshifts of the latter four systems to be
z_l=0.2-0.8 from the colors and magnitudes of the lensing galaxies. We find
that the image configurations of all systems are well reproduced by standard
mass models. Although these lenses will not be included in our statistical
sample of z_s<2.2 lenses, they expand the number of lensed quasars which can be
used for high-redshift galaxy and quasar studies.


title:
Mass models and environment of the new quadruply lensed quasar SDSS
  J1330+1810

abstract:
  We present the discovery of a new quadruply lensed quasar. The lens system,
SDSS J1330+1810 at z_s=1.393, was identified as a lens candidate from the
spectroscopic sample of the Sloan Digital Sky Survey. Optical and near-infrared
images clearly show four quasar images with a maximum image separation of
1.76", as well as a bright lensing galaxy. We measure a redshift of the lensing
galaxy of z_l=0.373 from absorption features in the spectrum. We find a
foreground group of galaxies at z=0.31 centred ~120" southwest of the lens
system. Simple mass models fit the data quite well, including the flux ratios
between images, although the lens galaxy appears to be ~1 mag brighter than
expected by the Faber-Jackson relation. Our mass modelling suggests that shear
from nearby structure is affecting the lens potential.


title: Multi-product splitting and Runge-Kutta-Nystrom integrators

abstract:
  The splitting of $\e^{h(A+B)}$ into a single product of $\e^{h A}$ and
$\e^{hB}$ results in symplectic integrators when $A$ and $B$ are classical Lie
operators. However, at high orders, a single product splitting, with
exponentially growing number of operators, is very difficult to derive. This
work shows that, if the splitting is generalized to a sum of products, then a
simple choice of the basis product reduces the problem to that of
extrapolation, with analytically known coefficients and only quadratically
growing number of operators. When a multi-product splitting is applied to
classical Hamiltonian systems, the resulting algorithm is no longer symplectic
but is of the Runge-Kutta-Nystr\"om (RKN) type. Multi-product splitting, in
conjunction with a special force-reduction process,explains why at orders $p=4$
and 6, RKN integrators only need $p-1$ force evaluations.


title: Edge-Graph Diameter Bounds for Convex Polytopes with Few Facets

abstract:
  We show that the edge graph of a 6-dimensional polytope with 12 facets has
diameter at most 6, thus verifying the d-step conjecture of Klee and Walkup in
the case of d=6. This implies that for all pairs (d,n) with n-d \leq 6 the
diameter of the edge graph of a d-polytope with n facets is bounded by 6, which
proves the Hirsch conjecture for all n-d \leq 6. We show this result by showing
this bound for a more general structure -- so-called matroid polytopes -- by
reduction to a small number of satisfiability problems.


title: Irreversible Monte Carlo Algorithms for Efficient Sampling

abstract:
  Equilibrium systems evolve according to Detailed Balance (DB). This principe
guided development of the Monte-Carlo sampling techniques, of which
Metropolis-Hastings (MH) algorithm is the famous representative. It is also
known that DB is sufficient but not necessary. We construct irreversible
deformation of a given reversible algorithm capable of dramatic improvement of
sampling from known distribution. Our transformation modifies transition rates
keeping the structure of transitions intact. To illustrate the general scheme
we design an Irreversible version of Metropolis-Hastings (IMH) and test it on
example of a spin cluster. Standard MH for the model suffers from the critical
slowdown, while IMH is free from critical slowdown.

categories: cond-mat.stat-mech cs.IT math.IT math.PR stat.AP


title:
Optically Thick Outflows of Supercritical Accretion Discs: Radiative
  Diffusion Approach

abstract:
  Highly supercritical accretion discs are probable sources of dense optically
thick axisymmetric winds. We introduce a new approach based on diffusion
approximation radiative transfer in a funnel geometry and obtain an analytical
solution for the energy density distribution inside the wind assuming that all
the mass, momentum and energy are injected well inside the spherization radius.
This allows to derive the spectrum of emergent emission for various inclination
angles. We show that self-irradiation effects play an important role altering
the temperature of the outcoming radiation by about 20% and the apparent X-ray
luminosity by a factor of 2-3. The model has been successfully applied to two
ULXs. The basic properties of the high ionization HII-regions found around some
ULXs are also easily reproduced in our assumptions.


title:
Intersecting random graphs and networks with multiple adjacency
  constraints: A simple example

abstract:
  When studying networks using random graph models, one is sometimes faced with
situations where the notion of adjacency between nodes reflects multiple
constraints. Traditional random graph models are insufficient to handle such
situations.
  A simple idea to account for multiple constraints consists in taking the
intersection of random graphs. In this paper we initiate the study of random
graphs so obtained through a simple example. We examine the intersection of an
Erdos-Renyi graph and of one-dimensional geometric random graphs. We
investigate the zero-one laws for the property that there are no isolated
nodes. When the geometric component is defined on the unit circle, a full
zero-one law is established and we determine its critical scaling. When the
geometric component lies in the unit interval, there is a gap in that the
obtained zero and one laws are found to express deviations from different
critical scalings. In particular, the first moment method requires a larger
critical scaling than in the unit circle case in order to obtain the one law.
This discrepancy is somewhat surprising given that the zero-one laws for the
absence of isolated nodes are identical in the geometric random graphs on both
the unit interval and unit circle.


title:
Detection of the 2175\AA~ extinction feature and 21-cm absorption in two
  MgII systems at z~1.3

abstract:
  We have discovered two dusty intervening MgII absorption systems at z~1.3 in
the Sloan Digital Sky Survey (SDSS) database. The overall spectra of both QSOs
are red (u-K>4.5 mag) and are well modelled by the composite QSO spectrum
reddened by the extinction curve from the Large Magellanic Cloud (LMC2)
Supershell redshifted to the rest-frame of the MgII systems. In particular, we
detect clearly the presence of the UV extinction bump at $\lambda_{\rm
rest}\sim 2175$~\AA. Absorption lines of weak transitions like
SiII$\lambda$1808, CrII$\lambda$2056, CrII+ZnII$\lambda$2062,
MnII$\lambda$2594, CaII$\lambda$3934 and TiII$\lambda$1910 from these systems
are detected even in the low signal-to-noise ratio and low resolution SDSS
spectra, suggesting high column densities of these species. The depletion
pattern inferred from these absorption lines is consistent with that seen in
the cold neutral medium of the LMC. Using the LMC A_V vs. N(HI) relationship we
derive N(HI)~$6\times 10^{21}$ cm$^{-2}$ in both systems. Metallicities are
close to solar. Giant Metrewave Radio Telescope (GMRT) observations of these
two relatively weak radio loud QSOs (f$_\nu$~50mJy) resulted in the detection
of 21-cm absorption in both cases. We show that the spin temperature of the gas
is of the order of or smaller than 500K. These systems provide a unique
opportunity to search for molecules and diffuse interstellar bands at z>1.


title: Convexit\'e holomorphe du rev\^etement de Malcev d'apr\`es S. Leroy

abstract:
  In these notes, we present the strategy employed by S. Leroy to attack the
nilpotent case of the Shafarevich conjecture. The projective case was treated
in a paper of L. Katzarkov but Leroy's proof is largely independant and works
in the K\"ahler setting as well. It is entirely based on the higher Albanese
manifolds constructed by R. Hain.


title: New Pulsating DB White Dwarf Stars from the Sloan Digital Sky Survey

abstract:
  We are searching for new He atmosphere white dwarf pulsators (DBVs) based on
the newly found white dwarf stars from the spectra obtained by the Sloan
Digital Sky Survey. DBVs pulsate at hotter temperature ranges than their better
known cousins, the H atmosphere white dwarf pulsators (DAVs or ZZ Ceti stars).
Since the evolution of white dwarf stars is characterized by cooling,
asteroseismological studies of DBVs give us opportunities to study white dwarf
structure at a different evolutionary stage than the DAVs. The hottest DBVs are
thought to have neutrino luminosities exceeding their photon luminosities
(Winget et al. 2004), a quantity measurable through asteroseismology.
Therefore, they can also be used to study neutrino physics in the stellar
interior. So far we have discovered nine new DBVs, doubling the number of
previously known DBVs. Here we report the new pulsators' lightcurves and power
spectra.


title: Superposition for Fixed Domains

abstract:
  Superposition is an established decision procedure for a variety of
first-order logic theories represented by sets of clauses. A satisfiable
theory, saturated by superposition, implicitly defines a minimal term-generated
model for the theory. Proving universal properties with respect to a saturated
theory directly leads to a modification of the minimal model's term-generated
domain, as new Skolem functions are introduced. For many applications, this is
not desired.
  Therefore, we propose the first superposition calculus that can explicitly
represent existentially quantified variables and can thus compute with respect
to a given domain. This calculus is sound and refutationally complete in the
limit for a first-order fixed domain semantics. For saturated Horn theories and
classes of positive formulas, we can even employ the calculus to prove
properties of the minimal model itself, going beyond the scope of known
superposition-based approaches.


title: Comparison between continuous wave and pulsed laser EQKD systems

abstract:
  Advances in quantum physics and computational complexity threaten the
security of present day cryptographic systems and have driven the development
of quantum key distribution (QKD). Entangled quantum key distribution (EQKD) is
a secure protocol that is based on fundamental quantum mechanics and is not
vulnerable to these threats. The primary figure of merit for QKD systems is
ability to generate secret bits. However, to date, methods that have been
developed to simulate the secret bit rate generation for EQKD systems have been
limited by techniques that do not provide a complete description of the quantum
state produced by the source. In this paper, we provide a complete description
and comparison of the secret bit rate for continuous-wave and pulsed laser EQKD
systems. In particular, we highlight the relevant Poissonian and thermal photon
statistics that affect the EQKD secret bit rate and use practical system
parameters and configurations to show regimes where one expects optimal
performance for each case.


title:
Enhanced superconducting pairing interaction in indium-doped tin
  telluride

abstract:
  The ferroelectric degenerate semiconductor Sn$_{1-\delta}$Te exhibits
superconductivity with critical temperatures, $T_c$, of up to 0.3 K for hole
densities of order 10$^{21}$ cm$^{-3}$. When doped on the tin site with greater
than $x_c$ $= 1.7(3)%$ indium atoms, however, superconductivity is observed up
to 2 K, though the carrier density does not change significantly. We present
specific heat data showing that a stronger pairing interaction is present for
$x > x_c$ than for $x < x_c$. By examining the effect of In dopant atoms on
both $T_c$ and the temperature of the ferroelectric structural phase
transition, $T_{SPT}$, we show that phonon modes related to this transition are
not responsible for this $T_c$ enhancement, and discuss a plausible candidate
based on the unique properties of the indium impurities.


title:
Pseudodifferential operator calculus for generalized Q-rank 1 locally
  symmetric spaces, I

abstract:
  This paper is the first of two papers constructing a calculus of
pseudodifferential operators suitable for doing analysis on Q-rank 1 locally
symmetric spaces and Riemannian manifolds generalizing these. This
generalization is the interior of a manifold with boundary, where the boundary
has the structure of a tower of fibre bundles. The class of operators we
consider on such a space includes those arising naturally from metrics which
degenerate to various orders at the boundary, in directions given by the tower
of fibrations. As well as Q-rank 1 locally symmetric spaces, examples include
Ricci-flat metrics on the complement of a divisor in a smooth variety
constructed by Tian and Yau. In this first part of the calculus construction,
parametrices are found for "fully elliptic differential \bfa-operators", which
are uniformly elliptic operators on these manifolds that satisfy an additional
invertibility condition at infinity. In the second part we will consider
operators that do not satisfy this condition.


title:
Potential barrier lowering and electrical transport at the
  LaAlO$_{3}$/SrTiO$_{3}$ heterointerface

abstract:
  Using a combination of vertical transport measurements across and lateral
transport measurements along the LaAlO$_{3}$/SrTiO$_{3}$ heterointerface, we
demonstrate that significant potential barrier lowering and band bending are
the cause of interfacial metallicity. Barrier lowering and enhanced band
bending extends over 2.5 nm into LaAlO$_{3}$ as well as SrTiO$_{3}$. We explain
origins of high-temperature carrier saturation, lower carrier concentration,
and higher mobility in the sample with the thinnest LaAlO$_{3}$ film on a
SrTiO$_{3}$ substrate. Lateral transport results suggest that parasitic
interface scattering centers limit the low-temperature lateral electron
mobility of the metallic channel.


title: Traversable wormholes from surgically modified Schwarzschild spacetimes

abstract:
  In this paper I present a new class of traversable wormholes. This is done by
surgically grafting two Schwarzschild spacetimes together in such a way that no
event horizon is permitted to form. This surgery concentrates a non--zero
stress--energy on the boundary layer between the two asymptotically flat
regions. I shall investigate this stress--energy in detail using the "junction
condition" formalism. A feature of the present analysis is that this class of
traversable wormholes is sufficiently simple for a (partial) dynamical
stability analysis to be carried out. The stability analysis places constraints
on the equation of state of the exotic matter that comprises the throat of the
wormhole.


title:
The annealing mechanism of AuGe/Ni/Au ohmic contacts to a
  two-dimensional electron gas in GaAs/AlGaAs heterostructures

abstract:
  Ohmic contacts to a two-dimensional electron gas (2DEG) in GaAs/AlGaAs
heterostructures are often realized by annealing of AuGe/Ni/Au that is
deposited on its surface. We studied how the quality of this type of ohmic
contact depends on the annealing time and temperature, and how optimal
parameters depend on the depth of the 2DEG below the surface. Combined with
transmission electron microscopy and energy-dispersive X-ray spectrometry
studies of the annealed contacts, our results allow for identifying the
annealing mechanism and proposing a model that can predict optimal annealing
parameters for a certain heterostructure.


title:
Symmetric collective attacks for the eavesdropping of symmetric quantum
  key distribution

abstract:
  We consider the collective eavesdropping of the BB84 and six-state protocols.
Since these protocols are symmetric in the eigenstates of conjugate bases, we
consider collective attacks having the same kind of symmetry. We then show how
these symmetric collective attacks are sufficiently strong in order to minimize
the Devetak-Winter rates. In fact, it is quite easy to construct simple
examples able to reach the unconditionally-secure key-rates of these protocols.


title: Skyrme Branes

abstract:
  We obtain static selfgravitating solitonic 3-brane solutions in the
Einstein-Skyrme model in 7D. These solitons correspond to a smooth version of
the previously discussed cosmic p-brane solutions. We show how the energy
momentum tensor of the Skyrme field is able to smooth out the singularities
found in the thin wall approximation and falls fast enough with the distance
from the core of the object so that asymptotically approaches the flat cosmic
p-brane metric.


title:
Understanding the electroluminescence emitted by single molecules in
  scanning tunneling microscopy experiments

abstract:
  We explore theoretically the electroluminescence of single molecules. We
adopt a local-electrode framework that is appropriate for scanning tunneling
microscopy (STM) experiments where electroluminescence originates from
individual molecules of moderate size on complex substrates: Couplings between
the STM tip and molecule and between the molecule and multiple substrate sites
are treated on the same footing, as local electrodes contacting the molecule.
Electron flow is modelled with the Lippmann-Schwinger Green function scattering
technique. The evolution of the electronic energy levels of the molecule under
bias is modelled assuming the total charge of the molecule to be invariant,
consistent with Coulomb blockade considerations, but that the electronic
occupations of the molecular HOMO and LUMO levels vary with changing bias. The
photon emission rate is calculated using Fermi's golden rule. We apply this
theoretical approach to the STM/Zn-etioporphyrin/Al2O3/NiAl(110) system, and
simulate various configurations of coupling strength between the molecule and
substrate. We compare our results to the experimental observations of Qiu,
Nazin and Ho [Science 299, 542 (2003)] for this system and find that our model
provides a comprehensive explanation of a multitude of previously unexplained
observations. These include the different types of current-voltage
characteristics (CVC's) that are observed experimentally, the observed
association of electroluminescence with some CVC's and not others and key
properties of the observed photon spectra. Theoretical predictions are
presented for further single-molecule electroluminescence experiments.


title: Applications of Multi-Valued Quantum Algorithms

abstract:
  This paper generalizes both the binary Deutsch-Jozsa and Grover algorithms to
$n$-valued logic using the quantum Fourier transform. Our extended
Deutsch-Jozsa algorithm is not only able to distinguish between constant and
balanced Boolean functions in a single query, but can also find closed
expressions for classes of affine logical functions in quantum oracles,
accurate to a constant term. Furthermore, our multi-valued extension of the
Grover algorithm for quantum database search requires fewer qudits and hence a
substantially smaller memory register, as well as fewer wasted information
states, to implement. We note several applications of these algorithms and
their advantages over the binary cases.


title: Properties of Scalar-Quark Systems in SU(3)c Lattice QCD

abstract:
  We perform the first study for the bound states of colored scalar particles
$\phi$ ("scalar quarks") in terms of mass generation with quenched SU(3)$_c$
lattice QCD. We investigate the bound states of $\phi$, $\phi^\dagger\phi$ and
$\phi\phi\phi$ ("scalar-quark hadrons"), as well as the bound states of $\phi$
and quarks $\psi$, i.e., $\phi^\dagger\psi$, $\psi\psi\phi$ and $\phi\phi\psi$
("chimera hadrons"). All these new-type hadrons including $\phi$ have a large
mass of several GeV due to large quantum corrections by gluons, even for zero
bare scalar-quark mass $m_\phi=0$ at $a^{-1}\sim 1{\rm GeV}$. We find a similar
$m_\psi$-dependence between $\phi^\dagger\psi$ and $\phi\phi\psi$, which
indicates their similar structure due to the large mass of $\phi$. From this
study, we conjecture that all colored particles generally acquire a large
effective mass due to dressed gluons.


title: Anomalous CMB north-south asymmetry

abstract:
  Several accurate analyses have revealed a statistically significant
North-South ecliptic asymmetry in the large-angle correlations strength of the
Cosmic Microwave Background (CMB) radiation temperature field data from the
Wilkinson Microwave Anisotropy Probe (WMAP). This asymmetry is inconsistent
with the statistical isotropy expected in the concordance cosmological model
LCDM. It has been suggested that a possible cause-effect relationship exists
between this large-angle anisotropy and the anomalous CMB quadrupole-octopole
planes alignment. In turn, this later phenomenon (or both) would be a
consequence of one or more of the following undesired effects in CMB data: a
systematic error in the data processing or in the instrument characterization,
residual foregrounds, and large-angle correlations induced by the incomplete
sky CMB data (cut-sky masks are needed to reject Galactic foregrounds). Here,
it is proved that the North-South (NS) asymmetry is unrelated to the quadrupole
(l=2) and the octopole (l=3) properties because we find, at high confidence
levels, such large-angle anisotropy in three- and five-year WMAP CMB maps
containing only the multipole components 4 <= l <= 10. The statistical
significance depends on both, the CMB map analyzed as well as the cut-sky mask
applied to exclude foregrounds. The significance level of the NS-asymmetry is
less in five-year WMAP data with KQ75 (> 90% CL) than it is in three-year data
with Kp0 (> 96% CL). Additionally, robustness tests show that the statistical
significance of the NS-asymmetry is affected by the use of the KQ85 and KQ75
masks in five-year single-frequency WMAP CMB maps, whereas it is insensitive
with respect to application of the Kp2 and Kp0 masks in three-year
single-frequency WMAP CMB maps.


title:
A Search for Z=-1 Dark Matter Annihilation Products in Cosmic Rays with
  AMS-01

abstract:
  The majority of mass in the universe has not been observed optically and is
termed dark matter. The supersymmetric neutralino provides an interesting dark
matter candidate, which may self-annihilate in our galaxy, producing particles
visible in the cosmic ray spectrum. During a ten day space shuttle flight, the
AMS-01 detector recorded over 100 million cosmic ray events. This analysis
searches for the products of neutralino annihilation in the AMS-01 Z=-1
spectrum, and uses the results to place limits on which supersymmetric and dark
matter halo distribution models are compatible.


title:
Inelastic and elastic collision rates for triplet states of ultracold
  strontium

abstract:
  We report measurement of the inelastic and elastic collision rates for
^{88}Sr atoms in the (5s5p)^3P_0 state in a crossed-beam optical dipole trap.
This is the first measurement of ultracold collision properties of a ^3P_0
level in an alkaline-earth atom or atom with similar electronic structure.
Since the (5s5p)^3P_0 state is the lowest level of the triplet manifold, large
loss rates indicate the importance of principle-quantum-number-changing
collisions at short range. We also provide an estimate of the collisional loss
rates for the (5s5p){^3P_2} state.


title: Triangulations of the sphere and degenerations of K3 surfaces

abstract:
  W. Thurston proved that to a triangulation of the sphere of non-negative
combinatorial curvature, one can associate an element in a certain lattice over
the Eisenstein integers such that its orbit is a complete invariant of the
triangulation. In this paper, we show that this association can be obtained
naturally by using Type III degenerations of K3 surfaces.


title: Finite index subgroups of fully residually free groups

abstract:
  Using graph-theoretic techniques for f.g. subgroups of $F^{\mathbb{Z}[t]}$ we
provide a criterion for a f.g. subgroup of a f.g. fully residually free group
to be of finite index. Moreover, we show that this criterion can be checked
effectively. Also we obtain an analogue of Greenberg-Stallings Theorem for f.g.
fully residually free groups, and prove that a f.g. non-abelian subgroup of a
f.g. fully residually free group is of finite index in its commensurator.


title: Applications of Bayesian Probability Theory in Astrophysics

abstract:
  Bayesian Inference is a powerful approach to data analysis that is based
almost entirely on probability theory. In this approach, probabilities model
{\it uncertainty} rather than randomness or variability. This thesis is
composed of a series of papers that have been published in various astronomical
journals during the years 2005-2008. The unifying thread running through the
papers is the use of Bayesian Inference to solve underdetermined inverse
problems in astrophysics. Firstly, a methodology is developed to solve a
question in gravitational lens inversion - using the observed images of
gravitational lens systems to reconstruct the undistorted source profile and
the mass profile of the lensing galaxy. A similar technique is also applied to
the task of inferring the number and frequency of modes of oscillation of a
star from the time series observations that are used in the field of
asteroseismology. For these complex problems, many of the required calculations
cannot be done analytically, and so Markov Chain Monte Carlo algorithms have
been used. Finally, probabilistic reasoning is applied to a controversial
question in astrobiology: does the fact that life formed quite soon after the
Earth constitute evidence that the formation of life is quite probable, given
the right macroscopic conditions?


title: Correlation effects in a discrete quantum random walk

abstract:
  We introduce history-dependent discrete-time quantum random walk models by
adding uncorrelated memory terms and also by modifying Hamiltonian of the
walker to include couplings with memory-keeping agents. We next numerically
study the correlation effects in these models. We also propose a correlation
exponent as a relevant and promising tool for investigation of correlation or
memory (hence non-Markovian) effects. Our analysis can easily be applied to
more realistic models in which different regimes may emerge because of
competition between different underlying physical mechanisms.


title: The modified K\"ahler-Ricci flow and solitons

abstract:
  We investigate the K\"ahler-Ricci flow modified by a holomorphic vector
field. We find equivalent analytic criteria for the convergence of the flow to
a K\"ahler-Ricci soliton. In addition, we relate the asymptotic behavior of the
scalar curvature along the flow to the lower boundedness of the modified
Mabuchi energy.


title: Fermion Triplet Dark Matter and Radiative Neutrino Mass

abstract:
  The neutral member of a Majorana fermion triplet (Sigma^+,Sigma^0,Sigma^-) is
proposed as a candidate for the dark matter of the Universe. It may also serve
as the seesaw anchor for obtaining a radiative neutrino mass.


title: Hidden gauge formalism for the radiative decays of axial-vector mesons

abstract:
  The radiative decay of the axial-vector resonances into a pseudoscalar meson
and a photon is studied using the vector meson Lagrangian obtained from the
hidden gauge symmetry (HGS) formalism. The formalism is well suited to study
this problem since it deals with pseudoscalar and vector mesons in a unified
way, respecting chiral invariance. We show explicitly the gauge invariance of
the set of diagrams that appear in the approach and evaluate the radiative
decay width of the a1(1260) and b1(1235) axial vector meson resonances into pi
gamma. We also include the contribution of loops involving anomalous couplings
and compare the results to those obtained previously within another formalism.


title: Implications of CTEQ PDF analysis for collider observables

abstract:
  In the context of a recent CTEQ6.6 global analysis, we review a new technique
for studying correlated theoretical uncertainties in hadronic observables
associated with imperfect knowledge of parton distribution functions (PDFs).
The technique is based on the computation of correlations between the predicted
values of physical observables in the Hessian matrix method. It can be used,
for example, to link the dominant PDF uncertainty in a hadronic cross section
to PDFs for individual parton flavors at well-defined $(x,\mu)$ values. As an
illustration, we apply the PDF correlation analysis to study regularities in
the PDF dependence of Z, W, and Higgs boson production cross sections at the
Tevatron and LHC.


title: Strange, charm, and bottom flavors in CTEQ global analysis

abstract:
  I discuss advances in the determination of strange, charm, and bottom quark
parton distribution functions obtained in the CTEQ6.5 and CTEQ6.6 global
analyses. These results affect electroweak precision observables and certain
new physics searches at the Large Hadron Collider. I focus, in particular, on
high-energy implications of the consistent treatment of heavy-quark threshold
effects in DIS in the general-mass factorization scheme; an independent
parametrization for the strangeness PDF; and the possible presence of
nonperturbative ("intrinsic") charm.


title: On principal fibrations associated with one algebra

abstract:
  In this paper we study two types of fibrations associated with a
3-dimensional unital associative irreducible algebra and their basic
properties. We investigate trivial principal fibrations of degenerate
semi-Euclidean sphere and their semi-conformal and projective models. We use
Norden normalization method for constructing second model.


title: Bilinear Approach to N=2 Supersymmetric KdV equations

abstract:
  The N=2 supersymmetric KdV equations are studied within the framework of
Hirota's bilinear method. For two such equations, namely $N=2, a=4$ and $N=2,
a=1$ supersymmetric KdV equations, we obtain the corresponding bilinear
formulations. Using them, we construct particular solutions for both cases. In
particular, a bilinear B\"{a}cklund transformation is given for the $N=2, a=1$
supersymmetric KdV equation.


title: Solving the conjugacy problem in Garside groups by cyclic sliding

abstract:
  We present a solution to the conjugacy decision problem and the conjugacy
search problem in Garside groups, which is theoretically simpler than the usual
one, with no loss of efficiency. This is done by replacing the well known
cycling and decycling operations by a new one, called cyclic sliding, which
appears to be a more natural choice.
  We give an analysis of the complexity of our algorithm in terms of
fundamental operations with simple elements, so our analysis is valid for every
Garside group. This paper intends to be self-contained, not requiring any
previous knowledge of prior algorithms, and includes all the details for the
algorithm to be implemented on a computer.


title:
Efficient Implementation of the Generalized Tunstall Code Generation
  Algorithm

abstract:
  A method is presented for constructing a Tunstall code that is linear time in
the number of output items. This is an improvement on the state of the art for
non-Bernoulli sources, including Markov sources, which require a (suboptimal)
generalization of Tunstall's algorithm proposed by Savari and analytically
examined by Tabus and Rissanen. In general, if n is the total number of output
leaves across all Tunstall trees, s is the number of trees (states), and D is
the number of leaves of each internal node, then this method takes O((1+(log
s)/D) n) time and O(n) space.


title:
Evolution of electronic structure of doped Mott insulators -
  reconstruction of poles and zeros of Green's function

abstract:
  We study evolution of metals from Mott insulators in the carrier-doped 2D
Hubbard model using a cluster extension of the dynamical mean-field theory.
While the conventional metal is simply characterized by the Fermi surface (pole
of the Green function G), interference of the zero surfaces of G with the pole
surfaces becomes crucial in the doped Mott insulators. Mutually interfering
pole and zero surfaces are dramatically transferred over the Mott gap, when
lightly doped holes synergetically loosen the doublon-holon binding. The heart
of the Mott physics such as the pseudogap, hole pockets, Fermi arcs, in-gap
states, and Lifshitz transitions appears as natural consequences of this global
interference in the frequency space.


title: Connected Components of Hurwitz Schemes and Malle's Conjecture

abstract:
  Let Z(X) be the number of degree-d extensions of F_q(t) with bounded
discriminant and some specified Galois group. The problem of computing Z(X) can
be related to a problem of counting F_q-rational points on certain Hurwitz
spaces. Ellenberg and Venkatesh used this idea to develop a heuristic for the
asymptotic behavior of Z'(X), the number of -geometrically connected-
extensions, and showed that this agrees with the conjectures of Malle for
function fields. We extend Ellenberg-Venkatesh's argument to handle the more
complicated case of covers of P^1 which may not be geometrically connected, and
show thatthe resulting heuristic suggests a natural modification to Malle's
conjecture which avoids the counterexamples, due to Kl\"uners, to the original
conjecture.


title:
Current-Induced Resonant Motion of a Magnetic Vortex Core: Effect of
  Nonadiabatic Spin Torque

abstract:
  The current-induced resonant excitation of a magnetic vortex core is
investigated by means of analytical and micromagnetic calculations. We find
that the radius and the phase shift of the resonant motion are not correctly
described by the analytical equations because of the dynamic distortion of a
vortex core. In contrast, the initial tilting angle of a vortex core is free
from the distortion and determined by the nonadiabaticity of the spin torque.
It is insensitive to experimentally uncontrollable current-induced in-plane
Oersted field. We propose that a time-resolved imaging of the very initial
trajectory of a core is essential to experimentally estimate the
nonadiabaticity.


title:
Heat Conduction and Entropy Production in Anharmonic Crystals with
  Self-Consistent Stochastic Reservoirs

abstract:
  We investigate a class of anharmonic crystals in $d$ dimensions, $d\ge 1$,
coupled to both external and internal heat baths of the Ornstein-Uhlenbeck
type. The external heat baths, applied at the boundaries in the 1-direction,
are at specified, unequal, temperatures $\tlb$ and $\trb$. The temperatures of
the internal baths are determined in a self-consistent way by the requirement
that there be no net energy exchange with the system in the non-equilibrium
stationary state (NESS). We prove the existence of such a stationary
self-consistent profile of temperatures for a finite system and show it
minimizes the entropy production to leading order in $(\tlb -\trb)$. In the
NESS the heat conductivity $\kappa$ is defined as the heat flux per unit area
divided by the length of the system and $(\tlb -\trb)$. In the limit when the
temperatures of the external reservoirs goes to the same temperature $T$,
$\kappa(T)$ is given by the Green-Kubo formula, evaluated in an equilibrium
system coupled to reservoirs all having the temperature $T$. This $\kappa(T)$
remains bounded as the size of the system goes to infinity. We also show that
the corresponding infinite system Green-Kubo formula yields a finite result.
Stronger results are obtained under the assumption that the self-consistent
profile remains bounded.

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


title: Counting Multisections in Conic Bundles over a Curve defined over F_q

abstract:
  For a given conic bundle X over a curve C defined over F_q, we count
irreducible branch covers of C in X of degree d and height e>>1. As a special
case, we get the number of algebraic numbers of degree d and height e over the
function field F_q (C).


title:
Carrier-mediated antiferromagnetic interlayer exchange coupling in
  diluted magnetic semiconductor multilayers Ga$_{1-x}$Mn$_x$As/GaAs:Be

abstract:
  We use neutron reflectometry to investigate the interlayer exchange coupling
between Ga$_{0.97}$Mn$_{0.03}$As ferromagnetic semiconductor layers separated
by non-magnetic Be-doped GaAs spacers. Polarized neutron reflectivity measured
below the Curie temperature of Ga$_{0.97}$Mn$_{0.03}$As reveals a
characteristic splitting at the wave vector corresponding to twice the
multilayer period, indicating that the coupling between the ferromagnetic
layers are antiferromagnetic (AFM). When the applied field is increased to
above the saturation field, this AFM coupling is suppressed. This behavior is
not observed when the spacers are undoped, suggesting that the observed AFM
coupling is mediated by charge carriers introduced via Be doping. The behavior
of magnetization of the multilayers measured by DC magnetometry is consistent
with the neutron reflectometry results.