title: Three Applications of the Cuntz Semigroup

abstract:
  Building on work of Elliott and coworkers, we present three applications of
the Cuntz semigroup: (i) for many simple C$^*$-algebras, the Thomsen semigroup
is recovered functorially from the Elliott invariant, and this yields a new
proof of Elliott's classification theorem for simple, unital AI algebras; (ii)
for the algebras in (i), classification of their Hilbert modules is similar to
the von Neumann algebra context; (iii) for the algebras in (i), approximate
unitary equivalence of self-adjoint operators is characterised in terms of the
Elliott invariant.


title: Instability of an equilibrium of a partial differential equation

abstract:
  A nonlinear parabolic differential equation with a quadratic nonlinearity is
presented which has at least one equilibrium. The linearization about this
equilibrium is asymptotically stable, but by using a technique inspired by H.
Fujita, we show that the equilibrium is unstable in the nonlinear setting. The
perturbations used have the property that they are small in every $L^p$ norm,
yet they result in solutions which fail to be global.


title: On capillary-gravity waves generated by a slow moving object

abstract:
  We investigate theoretically and experimentally the capillary-gravity waves
created by a small object moving steadily at the water-air interface along a
circular trajectory. It is well established that, for straight uniform motion,
no steady waves appear at velocities below the minimum phase velocity $c_{min}
= 23 \rm{cm \cdot s}^{-1}$. We show theoretically that no such velocity
threshold exists for a steady circular motion, for which, even at small
velocities, a finite wave drag is experienced by the object. This wave drag
originates from the emission of a spiral-like wave pattern. Our results are in
good agreement with direct experimental observations of the wave pattern
created by a circularly moving needle in contact with water. Our study leads to
new insights into the problem of animal locomotion at the water-air interface.


title:
Three-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations:
  Foreground Polarization

abstract:
  We present a full-sky model of polarized Galactic microwave emission based on
three years of observations by the Wilkinson Microwave Anisotropy Probe (WMAP)
at frequencies from 23 to 94 GHz. The model compares maps of the Stokes Q and U
components from each of the 5 WMAP frequency bands in order to separate
synchrotron from dust emission, taking into account the spatial and frequency
dependence of the synchrotron and dust components. This simple two-component
model of the interstellar medium accounts for at least 97% of the polarized
emission in the WMAP maps of the microwave sky. Synchrotron emission dominates
the polarized foregrounds at frequencies below 50 GHz, and is comparable to the
dust contribution at 65 GHz. The spectral index of the synchrotron component,
derived solely from polarization data, is -3.2 averaged over the full sky, with
a modestly flatter index on the Galactic plane. The synchrotron emission has
mean polarization fraction 2--4% in the Galactic plane and rising to over 20%
at high latitude, with prominent features such as the North Galactic Spur more
polarized than the diffuse component. Thermal dust emission has polarization
fraction 1% near the Galactic center, rising to 6% at the anti-center. Diffuse
emission from high-latitude dust is also polarized with mean fractional
polarization 0.036 +/- 0.011.


title: Metric Properties of Conflict Sets

abstract:
  In this paper we show that the tangent cone of a conflict set in $R^n$ is a
linear affine cone over a conflict set of smaller dimension and has dimension
$n-1$. Moreover we give an example where the conflict sets is not normally
embedded and not locally bi-Lipschitz equivalent to the corresponding tangent
cone.


title: Depolarization Currents in Fresh and Aged Corona Poled P(VDF-TFE) Films

abstract:
  Using short circuit and open circuit modifications of the thermally
stimulated depolarization current technique, relaxation currents have been
measured in corona poled copolymer of vinylidene fluoride with
tetrafluoroethylene in samples stored after poling for either 1 day, or 16
month. Two well structured peaks observed in aged samples were attributed to
relaxation of electret and ferroelectric components of the remnant
polarization. In fresh samples the two components were mixed forming one broad
peak. Relaxation of the space charge caused inversion of the current in the
open circuit mode both in fresh and in aged samples. Space charge peaks
extracted from the total current by appropriate calculations have shown that
the trapped charges were more stable than the polarization. It was suggested
that both the electret and the ferroelectric components of the remnant
polarization were accompanied by either space, or surface charges.


title:
Covers of Elliptic Curves and the Lower Bound for Slopes of Effective
  Divisors on $\bar{\mathcal M}_{g}$

abstract:
  Consider genus $g$ curves that admit degree $d$ covers to elliptic curves
only branched at one point with a fixed ramification type. The locus of such
covers forms a one parameter family $Y$ that naturally maps into the moduli
space of stable genus $g$ curves $\bar{\mathcal M}_{g}$. We study the geometry
of $Y$, and produce a combinatorial method by which to investigate its slope,
irreducible components, genus and orbifold points. As a by-product of our
approach, we find some equalities from classical number theory. Moreover, a
correspondence between our method and the viewpoint of square-tiled surfaces is
established. We also use our results to study the lower bound for slopes of
effective divisors on $\bar{\mathcal M}_{g}$.


title: Polynomial cocycles of Alexander quandles and applications

abstract:
  Cocycles are constructed by polynomial expressions for Alexander quandles. As
applications, non-triviality of some quandle homology groups are proved, and
quandle cocycle invariants of knots are studied. In particular, for an infinite
family of quandles, the non-triviality of quandle homology groups is proved for
all odd dimensions.


title: Lessons from Non-Abelian Plasma Instabilities in Two Spatial Dimensions

abstract:
  Plasma instabilities can play a fundamental role in quark-gluon plasma
equilibration in the high energy (weak coupling) limit. Early simulations of
the evolution of plasma instabilities in non-abelian gauge theory, performed in
one spatial dimension, found behavior qualitatively similar to traditional QED
plasmas. Later simulations of the fully three-dimensional theory found
different behavior, unlike traditional QED plasmas. To shed light on the origin
of this difference, we study the intermediate case of two spatial dimensions.
Depending on how the "two-dimensional'' theory is formulated, we can obtain
either behavior.


title:
The solitons redistribution in Bose-Einstein condensate in quasiperiodic
  optical lattice

abstract:
  We numerically study the dynamical excitations in Bose-Einstein condensate
(BEC) placed in periodic and quasi-periodic 2D optical lattice (OL). In case of
the repulsive mean-field interaction the BEC quantum tunnelling leads to a
progressive soliton's splitting and generating of secondary solitons, which
migrate to closest trapping potential minima. A nontrivial soliton dynamics
appears when a series of pi-pulses (phase kicks) are applied to the optical
lattice. Such sudden perturbation produces a dynamic redistribution of the
secondary solitons, leading to a formation of an artificial solitonic
superlattice. Different geometries of OL are analyzed.


title: Long Borel Hierarchies

abstract:
  We show that it is relatively consistent with ZF that the Borel hierarchy on
the reals has length $\omega_2$. This implies that $\omega_1$ has countable
cofinality, so the axiom of choice fails very badly in our model. A similar
argument produces models of ZF in which the Borel hierarchy has length any
given limit ordinal less than $\omega_2$, e.g., $\omega$ or
$\omega_1+\omega_1$.
  Latex2e: 24 pages plus 8 page appendix Latest version at:
www.math.wisc.edu/~miller


title: Strongly Interacting Higgs Sector Without Technicolor

abstract:
  Several years ago, we proposed a modification of the Standard Model, in which
the Higgs sector was stabilized by the addition of higher derivative operators,
similar to Lee-Wick Electrodynamics. We studied this theory extensively, both
using continuum Hamiltonian and path integral methods. We also reported
detailed lattice studies of the higher derivative Higgs sector. In view of some
recent revived interest in our original idea, we are providing here our
extensive notes from the time period on this topic. The key results were
already published in our papers at that time. The many additional details that
we make available here were previously available only in Chuan Liu's UCSD Ph.D.
thesis (1994). Very recently, our idea has been revived by other groups. In
view of the renewed interest, and to perhaps correct some misconceptions in the
literature, we are here making our original extensive notes available to the
wider community.


title:
Radiative lepton flavor violating decays in the Randall Sundrum
  background with localized leptons

abstract:
  We study the radiative lepton flavor violating l_i -> l_j\gamma decays in the
two Higgs doublet model, respecting the Randall Sundrum scenario and estimate
the contributions of the KK modes of left (right) handed charged lepton
doublets (singlets) on the branching ratios. We observe that the branching
ratios are sensitive to the contributions of the charged lepton KK modes.


title: Warping and Supersymmetry Breaking

abstract:
  We analyze supersymmetry breaking by anti-self-dual flux in the deformed
conifold. This theory has been argued to be a dual realization of susy breaking
by antibranes. As such, one might expect it to lead to a hierarchically small
breaking scale, but only if the warp factor is taken into account. We verify
this by explicitly computing the warp-modified moduli space metric. This leads
to a new term, with a power-like divergence at the conifold point, which lowers
the breaking scale. We finally point out various puzzles regarding the gauge
theory interpretation of these results.


title: The Steenrod problem of realizing polynomial cohomology rings

abstract:
  In this paper we completely classify which graded polynomial R-algebras in
finitely many even degree variables can occur as the singular cohomology of a
space with coefficients in R, a 1960 question of N. E. Steenrod, for a
commutative ring R satisfying mild conditions. In the fundamental case R = Z,
our result states that the only polynomial cohomology rings over Z which can
occur, are tensor products of copies of H^*(CP^\infty;Z) = Z[x_2],
H^*(BSU(n);Z) = Z[x_4,x_6,...,x_{2n}], and H^*(BSp(n):Z) =
Z[x_4,x_8,...,x_{4n}] confirming an old conjecture. Our classification extends
Notbohm's solution for R = F_p, p odd. Odd degree generators, excluded above,
only occur if R is an F_2-algebra and in that case the recent classification of
2-compact groups by the authors can be used instead of the present paper. Our
proofs are short and rely on the general theory of p-compact groups, but not on
classification results for these.


title:
Weight structures vs. $t$-structures; weight filtrations, spectral
  sequences, and complexes (for motives and in general)

abstract:
  This paper is dedicated to triangulated categories endowed with weight
structures (a new notion; D. Pauksztello has independently introduced them as
co-t-structures). This axiomatizes the properties of stupid truncations of
complexes in $K(B)$. We also construct weight structures for Voevodsky's
categories of motives and for various categories of spectra. A weight structure
$w$ defines Postnikov towers of objects; these towers are canonical and
functorial 'up to morphisms that are zero on cohomology'. For $Hw$ being the
heart of $w$ (in $DM_{gm}$ we have $Hw=Chow$) we define a canonical
conservative 'weakly exact' functor $t$ from our $C$ to a certain weak category
of complexes $K_w(Hw)$. For any (co)homological functor $H:C\to A$ for an
abelian $A$ we construct a weight spectral sequence $T:H(X^i[j])\implies
H(X[i+j])$ where $(X^i)=t(X)$; it is canonical and functorial starting from
$E_2$. This spectral sequences specializes to the 'usual' (Deligne's) weight
spectral sequences for 'classical' realizations of motives and to
Atiyah-Hirzebruch spectral sequences for spectra. Under certain restrictions,
we prove that $K_0(C)\cong K_0(Hw)$ and $K_0(End C)\cong K_0(End Hw)$.
  The definition of a weight structure is almost dual to those of a
t-structure; yet several properties differ. One can often construct a certain
$t$-structure which is 'adjacent' to $w$ and vice versa. This is the case for
the Voevodsky's $DM^{eff}_-$ (one obtains certain new Chow weight and
t-structures for it; the heart of the latter is 'dual' to $Chow^{eff}$) and for
the stable homotopy category. The Chow t-structure is closely related to
unramified cohomology.


title:
Does the Second Caustic Ring of Dark Matter Cause the Monoceros Ring of
  Stars ?

abstract:
  Caustic rings of dark matter were predicted to exist in the plane of the
Galaxy at radii $a_n \simeq 40 {\rm kpc}/n$ for $n = 1,2,3 ..$. The recently
discovered Monoceros Ring of stars is located near the $n=2$ caustic, prompting
us to consider a possible connection between these two objects. We identify two
processes through which the Monoceros Ring of stars may have formed. One
process is the migration of gas to an angular velocity minimum at the caustic
leading to enhanced star formation there. The other is the adiabatic
deformation of star orbits as the caustic slowly grows in mass and radius. The
second process predicts an order 100% enhancement of the density of disk stars
at the location of the caustic ring.


title: Infrared spectroscopy of HCOOH in interstellar ice analogues

abstract:
  Context: HCOOH is one of the more common species in interstellar ices with
abundances of 1-5% with respect to solid H2O. Aims: This study aims at
characterizing the HCOOH spectral features in astrophysically relevant ice
mixtures in order to interpret astronomical data. Methods: The ices are grown
under high vacuum conditions and spectra are recorded in transmission using a
Fourier transform infrared spectrometer. Pure HCOOH ices deposited at 15 K and
145 K are studied, as well as binary and tertiary mixtures containing H2O, CO,
CO2 and CH3OH. The mixture concentrations are varied from 50:50% to ~10:90% for
HCOOH:H2O. Binary mixtures of HCOOH:X and tertiary mixtures of HCOOH:H2O:X with
X = CO, CO2, and CH3OH, are studied for concentrations of ~10:90% and
~7:67:26%, respectively. Results: Pure HCOOH ice spectra show broad bands which
split around 120 K due to the conversion of a dimer to a chain-structure. Broad
single component bands are found for mixtures with H2O. Additional spectral
components are present in mixtures with CO, CO2 and CH3OH. The resulting peak
position, full width at half maximum and band strength depend strongly on ice
structure, temperature, matrix constituents and the HCOOH concentration.
Comparison of the solid HCOOH 5.9, 7.2, and 8.1 micron features with
astronomical data toward the low mass source HH 46 and high mass source W 33A
shows that spectra of binary mixtures do not reproduce the observed ice
features. However, our tertiary mixtures especially with CH3OH match the
astronomical data very well. Thus interstellar HCOOH is most likely present in
tertiary or more complex mixtures with H2O, CH3OH and potentially also CO or
CO2, providing constraints on its formation.


title:
XO-2b: Transiting Hot Jupiter in a Metal-rich Common Proper Motion
  Binary

abstract:
  We report on a V=11.2 early K dwarf, XO-2 (GSC 03413-00005), that hosts a
Rp=0.98+0.03/-0.01 Rjup, Mp=0.57+/-0.06 Mjup transiting extrasolar planet,
XO-2b, with an orbital period of 2.615857+/-0.000005 days. XO-2 has high
metallicity, [Fe/H]=0.45+/-0.02, high proper motion, mu_tot=157 mas/yr, and has
a common proper motion stellar companion with 31" separation. The two stars are
nearly identical twins, with very similar spectra and apparent magnitudes. Due
to the high metallicity, these early K dwarf stars have a mass and radius close
to solar, Ms=0.98+/-0.02 Msolar and Rs=0.97+0.02/-0.01 Rsolar. The high proper
motion of XO-2 results from an eccentric orbit (Galactic pericenter, Rper<4
kpc) well confined to the Galactic disk (Zmax~100 pc). In addition, the phase
space position of XO-2 is near the Hercules dynamical stream, which points to
an origin of XO-2 in the metal-rich, inner Thin Disk and subsequent dynamical
scattering into the solar neighborhood. We describe an efficient Markov Chain
Monte Carlo algorithm for calculating the Bayesian posterior probability of the
system parameters from a transit light curve.


title:
On constraining a transiting exoplanet's rotation rate with its transit
  spectrum

abstract:
  We investigate the effect of planetary rotation on the transit spectrum of an
extrasolar giant planet. During ingress and egress, absorption features arising
from the planet's atmosphere are Doppler shifted by of order the planet's
rotational velocity (~1-2 km/s) relative to where they would be if the planet
were not rotating. We focus in particular on the case of HD209458b, which ought
to be at least as good a target as any other known transiting planet. For
HD209458b, this shift should give rise to a small net centroid shift of ~60
cm/s on the stellar absorption lines. Using a detailed model of the
transmission spectrum due to a rotating star transited by a rotating planet
with an isothermal atmosphere, we simulate the effect of the planet's rotation
on the shape of the spectral lines, and in particular on the magnitude of their
width and centroid shift. We then use this simulation to determine the expected
signal-to-noise ratio for distinguishing a rotating from a non-rotating planet,
and assess how this S/N scales with various parameters of HD209458b. We find
that with a 6 m telescope, an equatorial rotational velocity of ~2 km/s could
be detected with a S/N~5 by accumulating the signal over many transits over the
course of several years. With a 30 m telescope, the time required to make such
a detection reduces to less than 2 months.


title:
Path Integration in QCD with Arbitrary Space-Dependent Static Color
  Potential

abstract:
  We perform path integral for a quark (antiquark) in the presence of an
arbitrary space-dependent static color potential A^a_0(x)(=-\int dx E^a(x))
with arbitrary color index a=1,2,...8 in SU(3) and obtain an exact
non-perturbative expression for the generating functional. We show that such a
path integration is possible even if one can not solve the Dirac equation in
the presence of arbitrary space-dependent potential. It may be possible to
further explore this path integral technique to study non-perturbative bound
state formation.


title:
Multiple-event probability in general-relativistic quantum mechanics: a
  discrete model

abstract:
  We introduce a simple quantum mechanical model in which time and space are
discrete and periodic. These features avoid the complications related to
continuous-spectrum operators and infinite-norm states. The model provides a
tool for discussing the probabilistic interpretation of generally-covariant
quantum systems, without the confusion generated by spurious infinities. We use
the model to illustrate the formalism of general-relativistic quantum
mechanics, and to test the definition of multiple-event probability introduced
in a companion paper. We consider a version of the model with unitary
time-evolution and a version without unitary time-evolution


title: An Interferometry-Free Protocol for Demonstrating Topological Order

abstract:
  We propose a protocol to demonstrate the topological order of a spin-1/2
lattice model with four-body interactions. Unlike other proposals, it does not
rely on the controlled movement of quasiparticles, thus eliminating the
addressing, decoherence and dynamical phase problems related to them. Rather,
the protocol profits from the degeneracy of the ground state. It involves the
addition of Zeeman terms to the original Hamiltonian that are used to create
holes and move them around in the system.


title:
Axionic symmetry gaugings in N=4 supergravities and their
  higher-dimensional origin

abstract:
  We study the class of four-dimensional N=4 supergravities obtained by gauging
the axionic shift and axionic rescaling symmetries. We formulate these theories
using the machinery of embedding tensors, characterize the full gauge algebras
and discuss several specific features of this family of gauged supergravities.
We exhibit in particular a generalized duality between massive vectors and
massive two-forms in four dimensions, inherited from the gauging of the shift
symmetry. We show that these theories can be deduced from higher dimensions by
a Scherk-Schwarz reduction, where a twist with respect to a non-compact
symmetry is required. The four-dimensional generalized duality plays a crucial
role in identifying the higher-dimensional ascendent.


title:
XMM-Newton observations of the first unidentified TeV gamma-ray source
  TeV J2032+4130

abstract:
  (abridged) The first unidentified very high energy gamma ray source (TeV
J2032+4130) in the Cygnus region has been the subject of intensive search for a
counterpart source at other wavelengths. A deep ($\approx 50$ ksec) exposure of
TeV J2032+4130 with \textit{XMM-Newton} has been obtained. The contribution of
point sources to the observed X-ray emission from TeV J2032+4130 is subtracted
from the data. The point-source subtracted X-ray data are analyzed using blank
sky exposures and regions adjacent to the position of TeV J2032+4130 in the
field of view covered by the XMM-Newton telescopes to search for diffuse X-ray
emission. An extended X-ray emission region with a full width half maximum
(FWHM) size of $\approx 12$ arc min is found. The centroid of the emission is
co-located with the position of TeV J2032+4130.The energy spectrum of the
emission coinciding with the position and extension of TeV J2032+4130 can be
modeled by a power-law model with a photon index
$\Gamma=1.5\pm0.2_\mathrm{stat}\pm0.3_\mathrm{sys}$ and an energy flux
integrated between 2 and 10 keV of $f_{2-10 \mathrm{keV}} \approx 7\cdot
10^{-13}$ ergs/(cm$^2$ s) which is lower than the very high energy gamma-ray
flux observed from TeV J2032+4130. We conclude that the faint extended X-ray
emission discovered in this observation is the X-ray counterpart of TeV
J2032+4130. Formally, it can not be excluded that the extended emission is due
to an unrelated population of faint, hot ($k_BT\approx 10$ keV) unresolved
point-sources which by chance coincides with the position and extension of TeV
J2032+4130. We discuss our findings in the frame of both hadronic and leptonic
gamma-ray production scenarios.


title: Critical phenomena in complex networks

abstract:
  The combination of the compactness of networks, featuring small diameters,
and their complex architectures results in a variety of critical effects
dramatically different from those in cooperative systems on lattices. In the
last few years, researchers have made important steps toward understanding the
qualitatively new critical phenomena in complex networks. We review the
results, concepts, and methods of this rapidly developing field. Here we mostly
consider two closely related classes of these critical phenomena, namely
structural phase transitions in the network architectures and transitions in
cooperative models on networks as substrates. We also discuss systems where a
network and interacting agents on it influence each other. We overview a wide
range of critical phenomena in equilibrium and growing networks including the
birth of the giant connected component, percolation, k-core percolation,
phenomena near epidemic thresholds, condensation transitions, critical
phenomena in spin models placed on networks, synchronization, and
self-organized criticality effects in interacting systems on networks. We also
discuss strong finite size effects in these systems and highlight open problems
and perspectives.

categories: cond-mat.stat-mech cs.NI math-ph math.MP physics.soc-ph


title: Statistics of an Unstable Barotropic Jet from a Cumulant Expansion

abstract:
  Low-order equal-time statistics of a barotropic flow on a rotating sphere are
investigated. The flow is driven by linear relaxation toward an unstable zonal
jet. For relatively short relaxation times, the flow is dominated by
critical-layer waves. For sufficiently long relaxation times, the flow is
turbulent. Statistics obtained from a second-order cumulant expansion are
compared to those accumulated in direct numerical simulations, revealing the
strengths and limitations of the expansion for different relaxation times.

categories: physics.flu-dyn cond-mat.stat-mech nlin.CD physics.ao-ph physics.comp-ph


title: When does a satellite knot fiber?

abstract:
  Necessary and sufficient conditions are given for a satellite knot to be
fibered. Any knot $\tilde k$ embeds in an unknotted solid torus $\tilde V$ with
arbitrary winding number in such a way that no satellite knot with pattern
$(\tilde V, \tilde k)$ is fibered. In particular, there exist nonfibered
satellite knots with fibered pattern and companion knots and nonzero winding
number.


title: Rolling to the tachyon vacuum in string field theory

abstract:
  We argue that the rolling-tachyon solution in cubic OSFT proceeds at late
times to precisely the analytic tachyon-vacuum solution constructed by Schnabl.
In addition, we demonstrate the relationship between the rolling-tachyon
solution and the standard BCFT description by showing that there is a finite
gauge transformation which relates the two.


title: Galactic X-ray binary jets

abstract:
  With their relatively fast variability time-scales, Galactic X-ray binaries
provide an excellent laboratory to explore the physics of accretion and related
phenomena, most notably outflows, over different regimes. After comparing the
phenomenology of jets in black hole X-ray binary systems to that of neutron
stars, here I discuss the role of the jet at very low Eddington ratios, and
present preliminary results obtained by fitting the broadband spectral energy
distribution of a quiescent black hole binary with a `maximally jet-dominated'
model.


title:
The Role of Reconstructed Surfaces in the Intrinsic Dissipative Dynamics
  of Silicon Nanoresonators

abstract:
  Dissipation in the flexural dynamics of doubly clamped nanomechanical bar
resonators is investigated using molecular dynamics simulation. The dependence
of the quality factor Q on temperature and the size of the resonator is
calculated from direct simulation of the oscillation of a series of Si <001>
bars with bare {100} dimerized surfaces. The bar widths range from 3.3 to
8.7nm, all with a fixed length of 22nm. The fundamental mode frequencies range
from 40 to 90GHz and Q from 10^2 near 1000K to 10^4 near 50K. The quality
factor is shown to be limited by defects in the reconstructed surface.


title: A Covariant Holographic Entanglement Entropy Proposal

abstract:
  With an aim towards understanding the time-dependence of entanglement entropy
in generic quantum field theories, we propose a covariant generalization of the
holographic entanglement entropy proposal of hep-th/0603001. Apart from
providing several examples of possible covariant generalizations, we study a
particular construction based on light-sheets, motivated in similar spirit to
the covariant entropy bound underlying the holographic principle. In
particular, we argue that the entanglement entropy associated with a specified
region on the boundary in the context of the AdS/CFT correspondence is given by
the area of a co-dimension two bulk surface with vanishing expansions of null
geodesics. We demonstrate our construction with several examples to illustrate
its reduction to the holographic entanglement entropy proposal in static
spacetimes. We further show how this proposal may be used to understand the
time evolution of entanglement entropy in a time varying QFT state dual to a
collapsing black hole background. Finally, we use our proposal to argue that
the Euclidean wormhole geometries with multiple boundaries should be regarded
as states in a non-interacting but entangled set of QFTs, one associated to
each boundary.


title: Checking Equivalence of Quantum Circuits and States

abstract:
  Quantum computing promises exponential speed-ups for important simulation and
optimization problems. It also poses new CAD problems that are similar to, but
more challenging, than the related problems in classical (non-quantum) CAD,
such as determining if two states or circuits are functionally equivalent.
While differences in classical states are easy to detect, quantum states, which
are represented by complex-valued vectors, exhibit subtle differences leading
to several notions of equivalence. This provides flexibility in optimizing
quantum circuits, but leads to difficult new equivalence-checking issues for
simulation and synthesis. We identify several different equivalence-checking
problems and present algorithms for practical benchmarks, including quantum
communication and search circuits, which are shown to be very fast and robust
for hundreds of qubits.


title: Exploring the structure of the quenched QCD vacuum with overlap fermions

abstract:
  Overlap fermions have an exact chiral symmetry on the lattice and are thus an
appropriate tool for investigating the chiral and topological structure of the
QCD vacuum. We study various chiral and topological aspects of quenched gauge
field configurations. This includes the localization and chiral properties of
the eigenmodes, the local structure of the ultraviolet filtered field strength
tensor, as well as the structure of topological charge fluctuations. We
conclude that the vacuum has a multifractal structure.


title:
Nonlinear Perturbations and Conservation Laws on Curved Backgrounds in
  GR and Other Metric Theories

abstract:
  The field-theoretical approach is reviewed. Perturbations in general
relativity as well as in an arbitrary $D$-dimensional metric theory are studied
on a background, which is a solution (arbitrary) of the theory. Lagrangian for
perturbations is defined, and field equations for perturbations are derived
from the variational principle. These equations are exact and equivalent to the
equations in the standard formulation, but can be approximate also. The
field-theoretical description is invariant under gauge (inner) transformations,
which can be presented both in exact and approximate forms. Following the usual
field-theoretical prescription, conserved quantities for perturbations are
constructed. Conserved currents are expressed through divergences of
superpotentials -- antisymmetric tensor densities. This form allows to relate a
necessity to consider local properties of perturbations with a theoretical
representation of the quasi-local nature of conserved quantities in metric
theories. Applications of the formalism in general relativity are discussed.
Generalized formulae for an arbitrary metric $D$-dimensional theory are tested
in the Einstein-Gauss-Bonnet gravity.


title: The Mass Function of Active Black Holes in the Local Universe

abstract:
  We present the first measurement of the black hole (BH) mass function for
broad-line active galaxies in the local Universe. Using the ~9000 broad-line
active galaxies from the Fourth Data Release of the Sloan Digital Sky Survey,
we construct a broad-line luminosity function that agrees very well with the
local soft X-ray luminosity function. Using standard virial relations, we then
convert observed broad-line luminosities and widths into BH masses. A mass
function constructed in this way has the unique capability to probe the mass
region <10^6 M_sun, which, while insignificant in terms of total BH mass
density, nevertheless may place important constraints on the mass distribution
of seed BHs in the early Universe. The characteristic local active BH has a
mass of ~10^7 M_sun radiating at 10% of the Eddington rate. The active fraction
is a strong function of BH mass; at both higher and lower masses the active
mass function falls more steeply than one would infer from the distribution of
bulge luminosity. The deficit of local massive radiating BHs is a well-known
phenomenon, while we present the first robust measurement of a decline in the
space density of active BHs at low mass.


title: Quark Coalescence based on a Transport Equation

abstract:
  We employ the Boltzmann equation for describing hadron production from a
quark-gluon plasma (QGP) in ultrarelativistic heavy-ion collisions. We propose
resonance formation in quark-antiquark scattering as the dominant
meson-production channel, which, in particular, ensures that energy is
conserved in the recombination process. This, in turn, facilitates a more
controlled extension of hadronization to low transverse momenta ($p_T$), and to
address the experimentally observed transition from a hydrodynamic regime to
constituent quark-number scaling (CQNS). Based on input distributions for
strange and charm quarks with azimuthal asymmetries, $v_2(p_T)$, characteristic
for RHIC energies, we recover CQNS at sufficiently high $p_T$, while at low
$p_T$ a scaling with transverse kinetic energy is found, reminiscent to
experiment. The dependence of the transition regime on microscopic QGP
properties, i.e. resonance widths and $Q$-values in the $q+\bar q \to M$
process, is elucidated.


title:
Exact half-BPS Type IIB interface solutions I: Local solution and
  supersymmetric Janus

abstract:
  The complete Type IIB supergravity solutions with 16 supersymmetries are
obtained on the manifold $AdS_4 \times S^2 \times S^2 \times \Sigma$ with
$SO(2,3) \times SO(3) \times SO(3)$ symmetry in terms of two holomorphic
functions on a Riemann surface $\Sigma$, which generally has a boundary. This
is achieved by reducing the BPS equations using the above symmetry
requirements, proving that all solutions of the BPS equations solve the full
Type IIB supergravity field equations, mapping the BPS equations onto a new
integrable system akin to the Liouville and Sine-Gordon theories, and mapping
this integrable system to a linear equation which can be solved exactly.
Amongst the infinite class of solutions, a non-singular Janus solution is
identified which provides the AdS/CFT dual of the maximally supersymmetric
Yang-Mills interface theory discovered recently. The construction of general
classes of globally non-singular solutions, including fully back-reacted $AdS_5
\times S^5$ and supersymmetric Janus doped with D5 and/or NS5 branes, is
deferred to a companion paper.


title: Quantum Dot in Z-shaped Graphene Nanoribbon

abstract:
  Stimulated by recent advances in isolating graphene, we discovered that
quantum dot can be trapped in Z-shaped graphene nanoribbon junciton. The
topological structure of the junction can confine electronic states completely.
By varying junction length, we can alter the spatial confinement and the number
of discrete levels within the junction. In addition, quantum dot can be
realized regardless of substrate induced static disorder or irregular edges of
the junction. This device can be used to easily design quantum dot devices.
This platform can also be used to design zero-dimensional functional nanoscale
electronic devices using graphene ribbons.


title:
Exact half-BPS Type IIB interface solutions II: Flux solutions and
  multi-Janus

abstract:
  Regularity and topology conditions are imposed on the exact Type IIB
solutions on $AdS_4 \times S^2 \times S^2 \times \Sigma $ with 16
supersymmetries, which were derived in a companion paper. We construct an
infinite class of regular solutions with varying dilaton, and non-zero 3-form
fluxes. Our solutions may be viewed as the fully back-reacted geometries of
$AdS_5 \times S^5$ (or more generally, Janus) doped with D5 and/or NS5 branes.
The solutions are parametrized by the choice of an arbitrary genus $g$
hyper-elliptic Riemann surface $\Sigma $ with boundary, all of whose branch
points are restricted to lie on a line. For genus 0, the Janus solution with 16
supersymmetries and 6 real parameters is recovered; its topology coincides with
that of $AdS_5 \times S^5$. The genus $g\geq 1$ solutions are parametrized by a
total of $4g+6$ real numbers, $2g-1$ of which are the real moduli of $\Sigma$.
The solutions have $2g+2$ asymptotic $AdS_5 \times S^5$ regions, $g$
three-spheres with RR 3-form charge, and another $g$ with NSNS 3-form charge.
Collapse of consecutive branch points of $\Sigma $ yields singularities which
correspond to D5 and NS5 branes in the probe limit. It is argued that the
AdS/CFT dual gauge theory to each of our solutions consists of a
2+1-dimensional planar interface on which terminate $2g+2$ half-Minkowski
3+1-dimensional space-time $\mathcal{N}=4$ super-Yang-Mills theories.
Generally, the $\\mathcal{N}=4$ theory in each Minkowski half-space-time may
have an independent value of the gauge coupling, and the interface may support
various operators, whose interface couplings are further free parameters of the
dual gauge theory.


title: Can the Internet cope with stress?

abstract:
  When will the Internet become aware of itself? In this note the problem is
approached by asking an alternative question: Can the Internet cope with
stress? By extrapolating the psychological difference between coping and
defense mechanisms a distributed software experiment is outlined which could
reject the hypothesis that the Internet is not a conscious entity.


title:
Entanglement, fidelity and topological entropy in a quantum phase
  transition to topological order

abstract:
  We present a numerical study of a quantum phase transition from a
spin-polarized to a topologically ordered phase in a system of spin-1/2
particles on a torus. We demonstrate that this non-symmetry-breaking
topological quantum phase transition (TOQPT) is of second order. The transition
is analyzed via the ground state energy and fidelity, block entanglement,
Wilson loops, and the recently proposed topological entropy. Only the
topological entropy distinguishes the TOQPT from a standard QPT, and
remarkably, does so already for small system sizes. Thus the topological
entropy serves as a proper order parameter. We demonstrate that our conclusions
are robust under the addition of random perturbations, not only in the
topological phase, but also in the spin polarized phase and even at the
critical point.


title: High-energy Cosmic Rays and Neutrinos from Semi-relativistic Hypernovae

abstract:
  The origin of the ultrahigh-energy (UHE) cosmic rays (CRs) from the second
knee ($\sim6\times10^{17}$eV) above in the CR spectrum is still unknown.
Recently, there has been growing evidence that a peculiar type of supernovae,
called hypernovae, are associated with sub-energetic gamma-ray bursts (GRBs),
such as SN1998bw/GRB980425 and SN2003lw/GRB031203. Such hypernovae appear to
have high (up to mildly relativistic) velocity ejecta, which may be linked to
the sub-energetic GRBs. Assuming a continuous distribution of the kinetic
energy of the hypernova ejecta as a function of its velocity $E_k\propto
(\Gamma\beta)^{-\alpha}$ with $\alpha\sim 2$, we find that 1) the external
shock wave produced by the high velocity ejecta of a hypernova can accelerate
protons up to energies as high as $10^{19} {\rm eV}$; 2) the cosmological
hypernova rate is sufficient to account for the energy flux above the second
knee; and 3) the steeper spectrum of CRs at these energies can arise in these
sources. In addition, hypernovae would also give rise to a faint diffuse UHE
neutrino flux, due to $p\gamma$ interactions of the UHE CRs with hypernova
optical-UV photons.


title: Pion Leptonic Decays and Supersymmetry

abstract:
  We compute supersymmetric contributions to pion leptonic (\pi_{l2}) decays in
the Minimal Supersymmetric Standard Model (MSSM). When R-parity is conserved,
the largest contributions to the ratio R_{e/\mu} = \Gamma[ \pi^+ \to e^+
\nu_e(\gamma)]/\Gamma[ \pi^+ \to \mu^+ \nu_\mu(\gamma)] arise from one-loop
(V-A)x(V-A) corrections. These contributions can be potentially as large as the
sensitivities of upcoming experiments; if measured, they would imply
significant bounds on the chargino and slepton sectors complementary to current
collider limits. We also analyze R-parity violating interactions, which may
produce a detectable deviation in R_{e/\mu} while remaining consistent with all
other precision observables.


title: EGT through Quantum Mechanics & from Statistical Physics to Economics

abstract:
  By analyzing the relationships between a socioeconomical system modeled
through evolutionary game theory and a physical system modeled through quantum
mechanics we show how although both systems are described through two theories
apparently different both are analogous and thus exactly equivalents. The
extensions of quantum mechanics to statistical physics and information theory
let us use some of their definitions for the best understanding of the behavior
of economics and biology. The quantum analogue of the replicator dynamics is
the von Neumann equation. A system in where all its members are in Nash
equilibrium is equivalent to a system in a maximum entropy state. Nature is a
game in where its players compete for a common welfare and the equilibrium of
the system that they are members. They act as a whole besides individuals like
they obey a rule in where they prefer to work for the welfare of the collective
besides the individual welfare.


title:
High Frequency QPOs in Neutron Stars and Black Holes: Probing Dense
  Matter and Strong Gravitational Fields

abstract:
  Quasi-periodic oscillations (QPOs) have been discovered in the X-ray emission
of many neutron stars and black holes. The QPOs with frequencies greater than
about 300 Hz are thought to be produced near the surfaces of neutron stars and
the event horizons of black holes. I first summarize some of the most important
properties of the QPOs seen in neutron star and black hole systems. I then
review some of the models that have been proposed and compare them with
observational data. Finally, I describe how these QPOs can be used to determine
the properties of dense matter and strong gravitational fields.


title: Swan conductors for p-adic differential modules, II: Global variation

abstract:
  Using a local construction from a previous paper, we exhibit a numerical
invariant, the differential Swan conductor, for an isocrystal on a variety over
a perfect field of positive characteristic overconvergent along a boundary
divisor; this leads to an analogous construction for certain p-adic and l-adic
representations of the etale fundamental group of a variety. We then
demonstrate some variational properties of this definition for overconvergent
isocrystals, paying special attention to the case of surfaces.


title: Nonholonomic Algebroids, Finsler Geometry, and Lagrange-Hamilton Spaces

abstract:
  We elaborate an unified geometric approach to classical mechanics,
Riemann-Finsler spaces and gravity theories on Lie algebroids provided with
nonlinear connection (N-connection) structure. There are investigated the
conditions when the fundamental geometric objects like the anchor, metric and
linear connection, almost sympletic and related almost complex structures may
be canonically defined by a N-connection induced from a regular Lagrangian (or
Hamiltonian), in mechanical models, or by generic off-diagonal metric terms and
nonholonomic frames, in gravity theories. Such geometric constructions are
modelled on nonholonomic manifolds provided with nonintegrable distributions
and related chains of exact sequences of submanifolds defining N-connections.
We investigate the main properties of the Lagrange, Hamilton, Finsler-Riemann
and Einstein-Cartan algebroids and construct and analyze exact solutions
describing such objects.


title: Ergodic Theory: Recurrence

abstract:
  We survey the impact of the Poincar\'e recurrence principle in ergodic
theory, especially as pertains to the field of ergodic Ramsey theory.


title: Three remarks on one dimensional bi-Lipschitz conjugacies

abstract:
  We show that bi-Lipschitz conjugacies between non singular one dimensional
systems are forced to be smooth, at least in the minimal (and ergodic) case.
This is however far from being true in the non minimal case. These results
clarify a classical work by Ghys and Tsuboi.


title:
Higgs boson production with one bottom quark including higher-order
  soft-gluon corrections

abstract:
  A Higgs boson produced in association with one or more bottom quarks is of
great theoretical and experimental interest to the high-energy community. A
precise prediction of its total and differential cross-section can have a great
impact on the discovery of a Higgs boson with large bottom-quark Yukawa
coupling, like the scalar (h^0 and H^0) and pseudoscalar (A^0) Higgs bosons of
the Minimal Supersymmetric Standard Model (MSSM) in the region of large
\tan\beta. In this paper we apply the threshold resummation formalism to
determine both differential and total cross-sections for b g \to b\Phi (where
\Phi = h^0, H^0), including up to next-to-next-to-next-to-leading order (NNNLO)
soft plus virtual QCD corrections at next-to-leading logarithmic (NLL)
accuracy. We present results for both the Fermilab Tevatron and the CERN Large
Hadron Collider (LHC).


title:
Enhancement of prompt photons in ultrarelativistic proton-proton
  collisions from nonlinear gluon evolution at small-$x$

abstract:
  In this paper we estimate the influence of nonlinear gluon evolution in the
production of prompt photons at the LHC pp collider. We assume the validity of
collinear factorization and consider the EHKQS parton distributions, which are
solutions of the GLR-MQ evolution equations and describe quite well the DESY
$ep$ HERA data, as input in our calculations. We find that both single and
double photon production are enhanced for low-$p_T$ photons and central
rapidities, while this effect is absent for the high-$p_T$ photons. The
implications of this effect for the Quark-Gluon Plasma searches and for the QCD
background to Higgs are also discussed.


title: Physisorption of positronium on quartz surfaces

abstract:
  The possibility of having positronium (Ps) physisorbed at a material surface
is of great fundamental interest, since it can lead to new insight regarding
quantum sticking and is a necessary first step to try to obtain a Ps$_2$
molecule on a material host. Some experiments in the past have produced
evidence for physisorbed Ps on a quartz surface, but firm theoretical support
for such a conclusion was lacking. We present a first-principles
density-functional calculation of the key parameters determining the
interaction potential between Ps and an $\alpha$-quartz surface. We show that
there is indeed a bound state with an energy of 0.14 eV, a value which agrees
very well with the experimental estimate of $\sim0.15$ eV. Further, a brief
energy analysis invoking the Langmuir-Hinshelwood mechanism for the reaction of
physisorbed atoms shows that the formation and desorption of a Ps$_2$ molecule
in that picture is consistent with the above results.


title: Prime Graphs and Exponential Composition of Species

abstract:
  In this paper, we enumerate prime graphs with respect to the Cartesian
multiplication of graphs. We use the unique factorization of a connected graph
into the product of prime graphs given by Sabidussi to find explicit formulas
for labeled and unlabeled prime graphs. In the case of species, we construct
the exponential composition of species based on the arithmetic product of
species of Maia and M\'endez and the quotient species, and express the species
of connected graphs as the exponential composition of the species of prime
graphs.


title: Cosmology and semi-conservation of computations in the universe

abstract:
  Resent works of Hawking and Susskind suggested that information is conserved
in the universe. We extend this thesis and propose that dynamics of information
- computations can conserve in Anti-de-Sitter cosmological model. Information
geometry formalism is proposed to analyze information in dynamical systems. We
consider entropy flow as a geometrical flow on statistical manifold and develop
a Dynamic Cores model to analyze migration of information in dynamical systems.
Geometrical flow on the statistical manifold was considered as a transition of
local dynamical systems in original d+1-dim AdS space to their delocalized
holographic representation in d-dim Conformal Field Theory (CFT). It was noted
that geometrical flow related to renormalization group flow and provide
semi-conservation of informational invariants. Those invariants interpreted as
types of computations.


title:
On the decay properties of solutions to a class of Schr\"odinger
  equations

abstract:
  We construct a local in time, exponentially decaying solution of the
one-dimensional variable coefficient Schrodinger equation by solving a
nonstandard boundary value problem. A main ingredient in the proof is a new
commutator estimate involving the projections P+ and P- onto the positive and
negative frequencies.


title: Cosmic rays from trans-relativistic supernovae

abstract:
  We derive constraints that must be satisfied by the sources of ~10^{15} to
~10^{18} eV cosmic rays, under the assumption that the sources are Galactic. We
show that while these constraints are not satisfied by ordinary supernovae
(SNe), which are believed to be the sources of <10^{15} eV cosmic rays, they
may be satisfied by the recently discovered class of trans-relativistic
supernovae (TRSNe), which were observed in association with gamma-ray bursts.
We define TRSNe as SNe that deposit a large fraction, f_R>10^{-2}, of their
kinetic energy in mildly relativistic, \gamma\beta>1, ejecta. The high velocity
ejecta enable particle acceleration to ~10^{18} eV, and the large value of f_R
(compared to f_R~10^{-7} for ordinary SNe) ensures that if TRSNe produce the
observed ~10^{18} eV cosmic ray flux, they do not overproduce the flux at lower
energies. This, combined with the estimated rate and energy production of
TRSNe, imply that Galactic TRSNe may be the sources of cosmic rays with
energies up to ~10^{18}eV .


title: Enumeration of Point-Determining Graphs

abstract:
  Point-determining graphs are graphs in which no two vertices have the same
neighborhoods, co-point-determining graphs are those whose complements are
point-determining, and bi-point-determining graphs are those both
point-determining and co-point-determining. Bicolored point-determining graphs
are point-determining graphs whose vertices are properly colored with white and
black. We use the combinatorial theory of species to enumerate these graphs as
well as the connected cases.


title:
Joint Detection and Identification of an Unobservable Change in the
  Distribution of a Random Sequence

abstract:
  This paper examines the joint problem of detection and identification of a
sudden and unobservable change in the probability distribution function (pdf)
of a sequence of independent and identically distributed (i.i.d.) random
variables to one of finitely many alternative pdf's. The objective is quick
detection of the change and accurate inference of the ensuing pdf. Following a
Bayesian approach, a new sequential decision strategy for this problem is
revealed and is proven optimal. Geometrical properties of this strategy are
demonstrated via numerical examples.


title:
Reliable Memories Built from Unreliable Components Based on Expander
  Graphs

abstract:
  In this paper, memories built from components subject to transient faults are
considered. A fault-tolerant memory architecture based on low-density
parity-check codes is proposed and the existence of reliable memories for the
adversarial failure model is proved. The proof relies on the expansion property
of the underlying Tanner graph of the code. An equivalence between the
Taylor-Kuznetsov (TK) scheme and Gallager B algorithm is established and the
results are extended to the independent failure model. It is also shown that
the proposed memory architecture has lower redundancy compared to the TK
scheme. The results are illustrated with specific numerical examples.


title:
Disparities in the Josephson vortex state electrodynamics of high-Tc
  cuprates

abstract:
  We report on far infrared measurements of interplane conductivity for
underdoped single-crystal YBa2Cu3Oy in magnetic field and situate these new
data within earlier work on two other high-Tc cuprate superconductors,
La(2-x)SrxCuO4 and Bi2Sr2CaCu2O(8+d). The three systems have displayed
apparently disparate electrodynamic responses in the Josephson vortex state
formed when magnetic field H is applied parallel to the CuO2 planes.
Specifically, there is discrepancy in the number and field dependence of
longitudinal modes observed. We compare and contrast these findings with
several models of the electrodynamics in the vortex state and suggest that most
differences can be reconciled through considerations of the Josephson vortex
lattice ground state as well as the c-axis and in-plane quasiparticle
dissipations.


title:
Comment on "Conformal invariance and stochastic Loewner evolution
  processes in two-dimensional Ising spin glasses"

abstract:
  By combining the scaling relation of Amoruso {\it et al.}, PRL {\bf 97},
267202 (2006) with standard droplet model assumptions, a value $\theta =
(\sqrt{6} - 3) / 2$ is obtained. This conjecture is reasonably consistent with
the best existing numerical calculations, and may be exact.


title:
High photon number path entanglement in the interference of
  spontaneously downconverted photon pairs with coherent laser light

abstract:
  We show that the quantum interference between downconverted photon pairs and
photons from coherent laser light can produce a maximally path entangled
N-photon output component with a fidelity greater than 90% for arbitrarily high
photon numbers. A simple beam splitter operation can thus transform the
2-photon coherence of down-converted light into an almost optimal N-photon
coherence.


title:
Horizon-Penetrating Transonic Accretion Disks around Rotating Black
  Holes

abstract:
  The stationary hydrodynamic equations for the transonic accretion disks and
flows around rotating black holes are presented by using the Kerr-Schild
coordinate where there is no coordinate singularity at the event horizon. We
use two types of the causal viscosity prescription, and the boundary conditions
for the transonic accretion flows are given at the sonic point. For one type of
the causal viscosity prescription we also add the boundary conditions at the
viscous point where the accreting radial velocity is nearly equal to the
viscous diffusion velocity. Based on the formalism for the transonic accretion
disks, after we present the calculation method of the transonic solutions, the
horizon-penetrating transonic solutions which smoothly pass the event horizon
are calculated for several types of the accretion flow models: the ideal
isothermal flows, the ideal and the viscous polytropic flows, the advection
dominated accretion flows (ADAFs) with the relativistic equation of state, the
adiabatic accretion disks, the standard accretion disks, the supercritical
accretion disks. These solutions are obtained for both non-rotating and
rotating black holes. The calculated accretion flows plunge into black hole
with finite three velocity smaller than the speed of light even at the event
horizon or inside the horizon, and the angular velocities of the accretion flow
at the horizon are generally different from the angular velocity of the
frame-dragging due to the black hole's rotation. These features contrast to the
results obtained by using the Boyer-Lindquist coordinate with the coordinate
singularity at the horizon.


title: y-scaling in Quasielastic Electron Scattering from Nuclei

abstract:
  A relativistic single particle model is used to calculate the inclusive
$(e,e')$ reaction from $A=$12, 40, 56, 197, and 208 nuclei in the quasielastic
region. We have shown that this model provides a very good description of the
available experimental cross sections when they are dominated by the
quasielastic process. In this paper we use this model to investigate the
dependence of $y$-scaling on electron kinematics, particularly the electron
scattering angle, for a range of squared four momentum transfer $0.20-0.80$
(GeV/c)$^2$. In this kinematic domain, Coulomb distortion of the electron does
not significantly affect scaling, but final state interactions of the knocked
out nucleon do affect scaling particularly when the nucleons have lower
energies. In general, we find that scaling works for this reaction, but at
lower values of the four momentum transfer, the scaling function does have some
dependence on the electron scattering angle. We also consider a modification of
y-scaling to include small binding energy effects as a function of Z and A and
show that there is some improvement in scaling.


title: Brundan-Kazhdan-Lusztig and super duality conjectures

abstract:
  We formulate a general super duality conjecture on connections between
parabolic categories O of modules over Lie superalgebras and Lie algebras of
type A, based on a Fock space formalism of their Kazhdan-Lusztig theories which
was initiated by Brundan. We show that the Brundan-Kazhdan-Lusztig (BKL)
polynomials for Lie superalgebra gl(m|n) in our parabolic setup can be
identified with the usual parabolic Kazhdan-Lusztig polynomials. We establish
some special cases of the BKL conjecture on the parabolic category O of
gl(m|n)-modules and additional results which support the BKL conjecture and
super duality conjecture.


title: Radion stabilization from the vacuum on flat extra dimensions

abstract:
  Volume stabilization in models with flat extra dimension could follow from
vacuum energy residing in the bulk when translational invariance is
spontaneously broken. We study a simple toy model that exemplifies this
mechanism which considers a massive scalar field with non trivial boundary
conditions at the end points of the compact space, and includes contributions
from brane and bulk cosmological constants. We perform our analysis in the
conformal frame where the radion field, associated with volume variations, is
defined, and present a general strategy for building stabilization potentials
out of those ingredients. We also provide working examples for the interval and
the $T^n/Z_2$ orbifold configuration.


title:
Direct Measurement of 2D and 3D Interprecipitate Distance Distributions
  from Atom-Probe Tomographic Reconstructions

abstract:
  Edge-to-edge interprecipitate distance distributions are critical for
predicting precipitation strengthening of alloys and other physical phenomena.
A method to calculate this 3D distance and the 2D interplanar distance from
atom-probe tomographic data is presented. It is applied to nanometer-sized
Cu-rich precipitates in an Fe-1.7 at.% Cu alloy. Experimental interprecipitate
distance distributions are discussed.


title: Mutual Fund Theorems when Minimizing the Probability of Lifetime Ruin

abstract:
  We show that the mutual fund theorems of Merton (1971) extend to the problem
of optimal investment to minimize the probability of lifetime ruin. We obtain
two such theorems by considering a financial market both with and without a
riskless asset for random consumption. The striking result is that we obtain
two-fund theorems despite the additional source of randomness from consumption.


title: A simple one dimensional glassy Kac model

abstract:
  We define a new family of random spin models with one-dimensional structure,
finite-range multi-spin interactions, and bounded average degree (number of
interactions in which each spin participates). Unfrustrated ground states can
be described as solutions of a sparse, band diagonal linear system, thus
allowing for efficient numerical analysis.
  In the limit of infinite interaction range, we recover the so-called XORSAT
(diluted p-spin) model, that is known to undergo a random first order phase
transition as the average degree is increased. Here we investigate the most
important consequences of a large but finite interaction range: (i)
Fluctuation-induced corrections to thermodynamic quantities; (ii) The need of
an inhomogeneous (position dependent) order parameter; (iii) The emergence of a
finite mosaic length scale. In particular, we study the correlation length
divergence at the (mean-field) glass transition.


title: A general homological Kleiman-Bertini theorem

abstract:
  Let G be a smooth algebraic group acting on a variety X. Let F and E be
coherent sheaves on X. We show that if all the higher Tor sheaves of F against
G-orbits vanish, then for generic g in G, the sheaf Tor^X_j(gF, E) vanishes for
all j >0. This generalizes a result of Miller and Speyer for transitive group
actions and a result of Speiser, itself generalizing the classical
Kleiman-Bertini theorem, on generic transversality, under a general group
action, of smooth subvarieties over an algebraically closed field of
characteristic 0.


title: Meta-Stable Brane Configurations with Five NS5-Branes

abstract:
  From an N=1 supersymmetric electric gauge theory with the gauge group SU(N_c)
x SU(N_c') with fundamentals for each gauge group, the bifundamentals and a
symmetric flavor and a conjugate symmetric flavor for SU(N_c), we apply Seiberg
dual to each gauge group independently and obtain two N=1 supersymmetric dual
magnetic gauge theories with dual matters including the gauge singlets. By
analyzing the F-term equations of the dual magnetic superpotentials, we
describe the intersecting brane configurations of type IIA string theory
corresponding to the meta-stable nonsupersymmetric vacua of these gauge
theories. The case where the above symmetric flavor is replaced by an
antisymmetric flavor is also discussed.


title: Fifteen Years of High-Resolution Radio Imaging of Supernova 1987A

abstract:
  Supernova 1987A in the Large Magellanic Cloud provides a spectacularly
detailed view of the aftermath of a core-collapse explosion. The supernova
ejecta initially coasted outward at more than 10% of the speed of light, but in
1990 were observed to decelerate rapidly as they began to encounter dense
circumstellar material expelled by the progenitor star. The resulting shock has
subsequently produced steadily brightening radio synchrotron emission, which is
resolved by the Australia Telescope Compact Array (ATCA) into an expanding
limb-brightened shell. Here we present 15 years of ATCA imaging of Supernova
1987A, at an effective angular resolution of 0.4 arcsec. We find that the radio
remnant has accelerated in its expansion over this period, from approx 3600
km/s in 1992 to approx 5200 km/s at the end of 2006. The published diameters of
the evolving X-ray shell have been ~15% smaller than the corresponding radio
values, but a simultaneous Fourier analysis of both radio and X-ray data
eliminates this discrepancy, and yields a current diameter for the shell in
both wave-bands of approx 1.7 arcsec. An asymmetric brightness distribution is
seen in radio images at all ATCA epochs: the eastern and western rims have
higher fluxes than the northern and southern regions, indicating that most of
the radio emission comes from the equatorial plane of the system, where the
progenitor star's circumstellar wind is thought to be densest. The eastern lobe
is brighter than and further from the supernova site than the western lobe,
suggesting an additional asymmetry in the initial distribution of supernova
ejecta.


title: Exact Floquet states of a driven condensate and their stabilities

abstract:
  We investigate the Gross-Pitaevskii equation for a classically chaotic
system, which describes an atomic Bose-Einstein condensate confined in an
optical lattice and driven by a spatiotemporal periodic laser field. It is
demonstrated that the exact Floquet states appear when the external
time-dependent potential is balanced by the nonlinear mean-field interaction.
The balance region of parameters is divided into a phase-continuing region and
a phase-jumping one. In the latter region, the Floquet states are
spatiotemporal vortices of nontrivial phase structures and zero-density cores.
Due to the velocity singularities of vortex cores and the blowing-up of
perturbed solutions, the spatiotemporal vortices are unstable periodic states
embedded in chaos. The stability and instability of these Floquet states are
numerically explored by the time evolution of fidelity between the exact and
numerical solutions. It is numerically illustrated that the stable Floquet
states could be prepared from the uniformly initial states by slow growth of
the external potential.


title:
Measurement of Ultra-Low Potassium Contaminations with Accelerator Mass
  Spectrometry

abstract:
  Levels of trace radiopurity in active detector materials is a subject of
major concern in low-background experiments. Among the radio-isotopes, $\k40$
is one of the most abundant and yet whose signatures are difficult to reject.
Procedures were devised to measure trace potassium concentrations in the
inorganic salt CsI as well as in organic liquid scintillator (LS) with
Accelerator Mass Spectrometry (AMS), giving, respectively, the
$\k40$-contamination levels of $\sim 10^{-10}$ and $\sim 10^{-13}$ g/g.
Measurement flexibilities and sensitivities are improved over conventional
methods. The projected limiting sensitivities if no excess of potassium signals
had been observed over background are $8 \times 10^{-13}$ g/g and $3 \times
10^{-17}$ g/g for the CsI and LS, respectively. Studies of the LS samples
indicate that the radioactive contaminations come mainly in the dye solutes,
while the base solvents are orders of magnitude cleaner. The work demonstrate
the possibilities of measuring naturally-occurring isotopes with the AMS
techniques.


title: Double solid twistor spaces: the case of arbitrary signature

abstract:
  In a recent paper (math.DG/0701278) we constructed a series of new Moishezon
twistor spaces which is a kind of variant of the famous LeBrun twistor spaces.
In this paper we explicitly give projective models of another series of
Moishezon twistor spaces on nCP^2 for arbitrary n>2, which can be regarded as a
generalization of the twistor spaces of a 'double solid type' on 3CP^2 studied
by Kreussler, Kurke, Poon and the author. Similarly to the twistor spaces of
'double solid type' on 3CP^2, projective models of present twistor spaces have
a natural structure of double covering of a CP^2-bundle over CP^1. We
explicitly give a defining polynomial of the branch divisor of the double
covering whose restriction to fibers are degree four. If n>3 these are new
twistor spaces, to the best of the author's knowledge. We also compute the
dimension of the moduli space of these twistor spaces. Differently from
math.DG/0701278, the present investigation is based on analysis of
pluri-(half-)anticanonical systems of the twistor spaces.


title: Arithmetic progressions of primes in short intervals

abstract:
  Green and Tao proved that the primes contains arbitrarily long arithmetic
progressions. We show that, essentially the same proof leads to the following
result: The primes in an short interval contains many arithmetic progressions
of any given length.


title: Radiation Pressure in Lyman-alpha Forest Clouds

abstract:
  The effective recombination coefficient, alpha_eff, is refined for optically
thin cases. Radiation pressure in Lyman-alpha and HeII Lyman-alpha is
calculated in terms of the number density and the mean free path. Pressure
equilibrium between Lyman-alpha clouds and an adiabatically expanding
inter-galactic medium is assumed, n_i T_i = n_c T_c. Numerical models of
isothermal and adiabatic expanding Lyman-alpha forest clouds are presented,
including evolving UV sources (QSOs), with various turn-on times z_on = 20, 10,
and 5, and with q_0 = 1/2 in a matter-dominated Friedmann-Robertson-Walker
Universe. These models lead to the conclusion that the radiation pressure and
QSO turn-on time are significant in determining the range of physical size, D,
and neutral hydrogen column density, N(HI), permitted for stable Lyman-alpha
forest clouds.
  This manuscript was written in 1989 and never submitted for publication.


title: The Hot Inter-Galactic Medium and the Cosmic Microwave Background

abstract:
  The physical characteristics of the Lyman-alpha forest cloud systems are
combined with observations on the baryonic mass density of the Universe and
constraints from primordial nucleosynthesis to set boundary conditions on the
Intergalactic Medium (IGM) at the epoch of z=2.5. The Universe is considered a
closed system and allowed to expand adiabatically from the epoch when QSOs
first ionized the IGM (5 <= z_on <= 20). The average kinetic energy of a gas is
calculated in the region where the gas transitions from relativistic to
non-relativistic behavior. All of the above measurements are then used to
determine the thermal history of the IGM in the redshift range 2.5 <= z <=
z_on. The hot IGM is assumed to inverse Compton scatter photons from the Cosmic
Microwave Background (CMBR) and consequently distort the CMBR as seen at the
present epoch. The temperature of the IGM at z=2.5 and the epoch z_on are
adjusted, within the constraints defined above, to give the best overall
agreement with published data on the temperature of the IGM. We find that the
model of the IGM proposed here does not grossly distort the CMBR, and in fact
agrees quite closely with the preliminary results from the Cosmic Background
Explorer (COBE) satellite. However, our model of the IGM cannot explain the
observed cosmic x ray background.
  This paper was originally written in 1990. It was never submitted for
publication.


title:
Bright solitary waves and trapped solutions in Bose-Einstein condensates
  with attractive interactions

abstract:
  We analyse the static solutions of attractive Bose-Einstein condensates under
transverse confinement, both with and without axial confinement. By full
numerical solution of the Gross-Pitaevskii equation and variational methods we
map out the condensate solutions, their energetic properties, and their
critical points for instability. With no axial confinement a bright solitary
wave solution will tend to decay by dispersion unless the interaction energy is
close to the critical value for collapse. In contrast, with axial confinement
the only decay mechanism is collapse. The stability of a bright solitary wave
solution increases with higher radial confinement. Finally we consider the
stability of dynamical states containing up to four solitons and find good
agreement with recent experiments.


title:
Discovery of the Putative Pulsar and Wind Nebula Associated with the TeV
  Gamma-ray Source HESS J1813-178

abstract:
  We present a Chandra X-ray observation of G12.82-0.02, a shell-like radio
supernova remnant coincident with the TeV gamma-ray source HESS J1813-178. We
resolve the X-ray emission from the co-located ASCA source into a point source
surrounded by structured diffuse emission that fills the interior of the radio
shell. The morphology of the diffuse emission strongly resembles that of a
pulsar wind nebula. The spectrum of the compact source is well-characterized by
a power-law with index Gamma approx 1.3, typical of young and energetic
rotation-powered pulsars. For a distance of 4.5 kpc, consistent with the X-ray
absorption and an association with the nearby star formation region W33, the
2-10 keV X-ray luminosities of the putative pulsar and nebula are L(PSR) =
3.2E33 ergs/s and L(PWN) = 1.4E34 ergs/s, respectively. Both the flux ratio of
L(PWN)/L(PSR) = 4.3 and the total luminosity of this system predict a pulsar
spin-down power of Edot > 1E37 ergs/s, placing it within the ten most energetic
young pulsars in the Galaxy. A deep search for radio pulsations using the
Parkes telescope sets an upper-limit of approx 0.07 mJy at 1.4 GHz for periods
>~ 50 ms. We discuss the energetics of this source, and consider briefly the
proximity of bright H2 regions to this and several other HESS sources, which
may produce their TeV emission via inverse Compton scattering.


title:
An Imaging Survey for Extrasolar Planets around 45 Close, Young Stars
  with SDI at the VLT and MMT

abstract:
  We present the results of a survey of 45 young (<250 Myr), close (<50 pc)
stars with the Simultaneous Differential Imager (SDI) implemented at the VLT
and the MMT for the direct detection of extrasolar planets. As part of the
survey, we observed 54 objects total, of which 45 were close, young stars, 2
were somewhat more distant (<150 pc), very young (<10 Myr) stars, 3 were stars
with known radial velocity planets, and 4 were older, very nearby (<20 pc)
solar analogues. Our SDI devices use a double Wollaston prism and a quad filter
to take images simultaneously at 3 wavelengths surrounding the 1.62 um methane
absorption bandhead found in the spectrum of cool brown dwarfs and gas giant
planets. In our VLT data, we achieved H band contrasts > 10 mag (5 sigma) at a
separation of 0.5" from the primary star on 45% of our targets and H band
contrasts of > 9 mag at a separation of 0.5'' on 80% of our targets. With this
degree of attenuation, we should be able to image (5sigma detection) a 5
M_{Jup} planet 15 AU from a 70 Myr K1 star at 15 pc or a 5 M_{Jup} planet at 2
AU from a 12 Myr M star at 10 pc. We believe that our SDI images are the
highest contrast astronomical images ever made from ground or space for methane
rich companions <1'' from their star. For the best 20 of our survey stars, we
attained 50% 5 sigma completeness for 6-10 M_Jup planets at semi-major axes of
20-40 AU. Thus, our completeness levels are sufficient to significantly test
theoretical planet distributions. From our survey null result, we can rule out
(at the 98% confidence/2.0sigma level) a model planet population using a planet
distribution where N(a) $\propto$ constant out to a distance of 45 AU (further
model assumptions discussed within).


title: An Embedding for General Relativity and its Implications for New Physics

abstract:
  We show that any solution of the 4D Einstein equations of general relativity
in vacuum with a cosmological constant may be embedded in a solution of the 5D
Ricci-flat equations with an effective 4D cosmological "constant" that is a
specific function of the extra coordinate. For unified theories of the forces
in higher dimensions, this has major physical implications.


title:
Inflation in minimal left-right symmetric model with spontaneous
  D-parity breaking

abstract:
  We present a simplest inflationary scenario in the minimal left-right
symmetric model with spontaneous D-parity breaking, which is a well motivated
particle physics model for neutrino masses. This leads us to connect the
observed anisotropies in the cosmic microwave background to the sub-eV neutrino
masses. The baryon asymmetry via the leptogenesis route is also discussed
briefly.


title: Semiparametric efficiency in GMM models with auxiliary data

abstract:
  We study semiparametric efficiency bounds and efficient estimation of
parameters defined through general moment restrictions with missing data.
Identification relies on auxiliary data containing information about the
distribution of the missing variables conditional on proxy variables that are
observed in both the primary and the auxiliary database, when such distribution
is common to the two data sets. The auxiliary sample can be independent of the
primary sample, or can be a subset of it. For both cases, we derive bounds when
the probability of missing data given the proxy variables is unknown, or known,
or belongs to a correctly specified parametric family. We find that the
conditional probability is not ancillary when the two samples are independent.
For all cases, we discuss efficient semiparametric estimators. An estimator
based on a conditional expectation projection is shown to require milder
regularity conditions than one based on inverse probability weighting.


title: The Cox Ring of $\bar{M}_{0,6}$

abstract:
  We prove that the Cox ring of $\bar{M}_{0,6}$, the moduli space of stable,
rational curves with 6 marked points, is finitely generated by sections
corresponding to the boundary divisors and divisors which are pull-backs of the
hyperelliptic locus in $\bar{M}_3$, the moduli space of stable, genus 3 curves,
via morphisms that send a 6-pointed rational curve to a curve with 3 nodes by
identifying 3 pairs of points. In particular, this gives a self-contained proof
of Hassett and Tschinkel's result about the effective cone of $\bar{M}_{0,6}$
being generated by the above mentioned divisors.


title:
A note about the factorization of the angular part of the Laplacian and
  its application to the time-independent Schr\"odinger equation

abstract:
  Removing al least one point from the unit sphere in $ R^{3}$ allows to
factorize the angular part of the laplacian with a Cauchy-Riemann type
operator. Solutions to this operator define a complex algebra of potential
functions. A family of these solutions is shown to be normalizable on the
sphere so it is possible to construct associate solutions for every radial
solution to the time-independant Schr\"odinger equation with a radial
potential, such that this family of solutions is square integrable in $R^{3}$.
While this family of associated solutions are singular on at least one
half-plane, they are square-integrable in almost all of $R^{3}$.


title: Low Mass Scalar Mesons and Related Topics

abstract:
  We give a brief survey on the physical significance of the low-mass scalar
mesons in QCD, and also report on recent lattice studies on the sigma and kappa
mesons. The importance to explore the in-medium properties of the hadrons is
mentioned.


title:
Fluctuation relation and pairing rule for Lyapunov exponents of inertial
  particles in turbulence

abstract:
  We study the motion of small particles in a random turbulent flow assuming
linear law of friction. We derive a symmetry relation obeyed by the large
deviations of the finite time Lyapunov exponents in the phase space. The
relation applies when either the statistics of the strain matrix is invariant
under the transposition or when it is time-reversible. We show that, as a
result, the Lyapunov exponents come in pairs which sum is equal to minus the
inverse relaxation time of the particles. We use the pairing to consider the
Kaplan-Yorke dimension of the particles attractor in the phase space. In
particular, the results apply to case of the flow which is white noise in time.


title:
Revelations of the E_6/U(1)_N Model: Two-Loop Neutrino Mass and Dark
  Matter

abstract:
  The E_6/U(1)_N gauge extension of the Supersymmetric Standard Model, first
proposed by Ma, is shown to have exactly the requisite ingredients to realize
the important new idea that dark matter is the origin of neutrino mass. With
the implementation of a discrete Z_2 X Z_2 symmetry, and particle content given
by three {27} representations of E_6, neutrino masses are naturally generated
in two loops, with candidates of dark matter in the loops. All particles of
this model are expected to be at or below the TeV scale, allowing them to be
observable at the LHC.


title:
Driven Spin Systems as Quantum Thermodynamic Machines: Fundamental
  Limits

abstract:
  We show that coupled two level systems like qubits studied in quantum
information can be used as a thermodynamic machine. At least three qubits or
spins are necessary and arranged in a chain. The system is interfaced between
two split baths and the working spin in the middle is externally driven. The
machine performs Carnot-type cycles and is able to work as heat pump or engine
depending on the temperature difference of the baths $\Delta T$ and the energy
differences in the spin system $\Delta E$. It can be shown that the efficiency
is a function of $\Delta T$ and $\Delta E$.


title:
Deterministic Factors of Stock Networks based on Cross-correlation in
  Financial Market

abstract:
  The stock market has been known to form homogeneous stock groups with a
higher correlation among different stocks according to common economic factors
that influence individual stocks. We investigate the role of common economic
factors in the market in the formation of stock networks, using the arbitrage
pricing model reflecting essential properties of common economic factors. We
find that the degree of consistency between real and model stock networks
increases as additional common economic factors are incorporated into our
model. Furthermore, we find that individual stocks with a large number of links
to other stocks in a network are more highly correlated with common economic
factors than those with a small number of links. This suggests that common
economic factors in the stock market can be understood in terms of
deterministic factors.


title: An analytic solution for one-dimensional quantum walks

abstract:
  The first general analytic solutions for the one-dimensional walk in position
and momentum space are derived. These solutions reveal, among other things, new
symmetry features of quantum walk probability densities and further insight
into the behaviour of their moments. The analytic expressions for the quantum
walk probability distributions provide a means of modelling quantum phenomena
that is analogous to that provided by random walks in the classical domain.


title: Neural networks with transient state dynamics

abstract:
  We investigate dynamical systems characterized by a time series of distinct
semi-stable activity patterns, as they are observed in cortical neural activity
patterns. We propose and discuss a general mechanism allowing for an adiabatic
continuation between attractor networks and a specific adjoined transient-state
network, which is strictly dissipative. Dynamical systems with transient states
retain functionality when their working point is autoregulated; avoiding
prolonged periods of stasis or drifting into a regime of rapid fluctuations. We
show, within a continuous-time neural network model, that a single local
updating rule for online learning allows simultaneously (i) for information
storage via unsupervised Hebbian-type learning, (ii) for adaptive regulation of
the working point and (iii) for the suppression of runaway synaptic growth.
Simulation results are presented; the spontaneous breaking of time-reversal
symmetry and link symmetry are discussed.

categories: cond-mat.dis-nn astro-ph cond-mat.other nlin.AO q-bio.NC


title: Baryon Asymmetry in a Heavy Moduli Scenario

abstract:
  In some models of supersymmetry breaking, modulus fields are heavy enough to
decay before BBN. But the large entropy produced via moduli decay significantly
dilutes the preexisting baryon asymmetry of the universe. We study whether
Affleck-Dine mechanism can provide enough baryon asymmetry which survives the
dilution, and find several situations in which desirable amount of baryon
number remains after the dilution. The possibility of non-thermal dark matter
is also discussed. This provides the realistic cosmological scenario with heavy
moduli.


title: Cosmological test of the Yilmaz theory of gravity

abstract:
  We test the Yilmaz theory of gravitation by working out the corresponding
Friedmann-type equations generated by assuming the Friedmann-Robertson-Walker
cosmological metrics. In the case that space is flat the theory is consistent
only with either a completely empty universe or a negative energy vacuum that
decays to produce a constant density of matter. In both cases the total energy
remains zero at all times, and in the latter case the acceleration of the
expansion is always negative. To obtain a more flexible and potentially more
realistic cosmology, the equation of state relating the pressure and energy
density of the matter creation process must be different from the vacuum, as
for example is the case in the steady-state models of Gold, Bondi, Hoyle and
others. The theory does not support the cosmological principle for curved space
K =/= 0 cosmological metrics.


title: Constructions of q-Ary Constant-Weight Codes

abstract:
  This paper introduces a new combinatorial construction for q-ary
constant-weight codes which yields several families of optimal codes and
asymptotically optimal codes. The construction reveals intimate connection
between q-ary constant-weight codes and sets of pairwise disjoint combinatorial
designs of various types.


title: Exact beta function from the holographic loop equation of large-N QCD_4

abstract:
  We construct and study a previously defined quantum holographic effective
action whose critical equation implies the holographic loop equation of large-N
QCD_4 for planar self-avoiding loops in a certain regularization scheme. We
extract from the effective action the exact beta function in the given scheme.
For the Wilsonean coupling constant the beta function is exacly one loop and
the first coefficient agrees with its value in perturbation theory. For the
canonical coupling constant the exact beta function has a NSVZ form and the
first two coefficients agree with their value in perturbation theory.


title: Are Advanced Potentials Anomalous?

abstract:
  Advanced electromagnetic potentials are indigenous to the classical Maxwell
theory. Generally however they are deemed undesirable and are forcibly
excluded, destroying the theory's inherent time-symmetry. We investigate the
reason for this, pointing out that it is not necessary and in some cases is
counter-productive. We then focus on the direct-action theory in which the
advanced and retarded contributions are present symmetrically, with no
opportunity to supplement the particular integral solution of the wave equation
with an arbitrary complementary function. One then requires a plausible
explanation for the observed broken symmetry that, commonly, is understood
cannot be met by the Wheeler-Feynman mechanism because the necessary boundary
condition cannot be satisfied in acceptable cosmologies. We take this
opportunity to argue that the boundary condition is already met by all
expanding cosmologies simply as a result of cosmological red-shift. A
consequence is that the cosmological and thermodynamic arrows of time can be
equated, the direct action version of EM is preferred, and that advanced
potentials are ubiquitous.


title: Dynamical Friction of a Circular-Orbit Perturber in a Gaseous Medium

abstract:
  We investigate the gravitational wake due to, and dynamical friction on, a
perturber moving on a circular orbit in a uniform gaseous medium using a
semi-analytic method. This work is a straightforward extension of Ostriker
(1999) who studied the case of a straight-line trajectory. The circular orbit
causes the bending of the wake in the background medium along the orbit,
forming a long trailing tail. The wake distribution is thus asymmetric, giving
rise to the drag forces in both opposite (azimuthal) and lateral (radial)
directions to the motion of the perturber, although the latter does not
contribute to orbital decay much. For subsonic motion, the density wake with a
weak tail is simply a curved version of that in Ostriker and does not exhibit
the front-back symmetry. The resulting drag force in the opposite direction is
remarkably similar to the finite-time, linear-trajectory counterpart. On the
other hand, a supersonic perturber is able to overtake its own wake, possibly
multiple times, and develops a very pronounced tail. The supersonic tail
surrounds the perturber in a trailing spiral fashion, enhancing the perturbed
density at the back as well as far front of the perturber. We provide the
fitting formulae for the drag forces as functions of the Mach number, whose
azimuthal part is surprisingly in good agreement with the Ostriker's formula,
provided Vp t=2 Rp, where Vp and Rp are the velocity and orbital radius of the
perturber, respectively.


title:
An efficient centralized binary multicast network coding algorithm for
  any cyclic network

abstract:
  We give an algorithm for finding network encoding and decoding equations for
error-free multicasting networks with multiple sources and sinks. The algorithm
given is efficient (polynomial complexity) and works on any kind of network
(acyclic, link cyclic, flow cyclic, or even in the presence of knots). The key
idea will be the appropriate use of the delay (both natural and additional)
during the encoding. The resulting code will always work with finite delay with
binary encoding coefficients.


title:
About the domino problem in the hyperbolic plane, a new solution:
  complement

abstract:
  In this paper, we complete the construction of paper arXiv:cs.CG/0701096v2.
Together with the proof contained in arXiv:cs.CG/0701096v2, this paper
definitely proves that the general problem of tiling the hyperbolic plane with
{\it \`a la} Wang tiles is undecidable.


title: Percolation transition in networks with degree-degree correlation

abstract:
  We introduce an exponential random graph model for networks with a fixed
degree distribution and with a tunable degree-degree correlation. We then
investigate the nature of a percolation transition in the correlated network
with the Poisson degree distribution. It is found that negative correlation is
irrelevant in that the percolation transition in the disassortative network
belongs to the same universality class of the uncorrelated network. Positive
correlation turns out to be relevant. The percolation transition in the
assortative network is characterized by the non-diverging mean size of finite
clusters and power-law scalings of the density of the largest cluster and the
cluster size distribution in the non-percolating phase as well as at the
critical point. Our results suggest that the unusual type percolation
transition in the growing network models reported recently may be inherited
from the assortative degree-degree correlation.


title:
Link concordance, homology cobordism, and Hirzebruch-type defects from
  iterated p-covers

abstract:
  We obtain new invariants of topological link concordance and homology
cobordism of 3-manifolds from Hirzebruch-type intersection form defects of
towers of iterated p-covers. Our invariants can extract geometric information
from an arbitrary depth of the derived series of the fundamental group, and can
detect torsion which is invisible via signature invariants. Applications
illustrating these features include the following: (1) There are infinitely
many homology equivalent rational 3-spheres which are indistinguishable via
multisignatures, eta-invariants, and L2-signatures but have distinct homology
cobordism types. (2) There is an infinite family of 2-torsion (amphichiral)
knots, including the figure eight knot, with non-slice iterated Bing doubles;
as a special case, we give the first proof of the conjecture that the Bing
double of the figure eight knot is not slice. (3) There exist infinitely many
torsion elements at any depth of the Cochran-Orr-Teichner filtration of link
concordance.


title: Bounding network spectra for network design

abstract:
  The identification of the limiting factors in the dynamical behavior of
complex systems is an important interdisciplinary problem which often can be
traced to the spectral properties of an underlying network. By deriving a
general relation between the eigenvalues of weighted and unweighted networks,
here I show that for a wide class of networks the dynamical behavior is tightly
bounded by few network parameters. This result provides rigorous conditions for
the design of networks with predefined dynamical properties and for the
structural control of physical processes in complex systems. The results are
illustrated using synchronization phenomena as a model process.


title: Lens space surgeries on A'Campo's divide knots

abstract:
  It is proved that every knot in the major subfamilies of J. Berge's lens
space surgery (i.e., knots yielding a lens space by Dehn surgery) is presented
by an L-shaped (real) plane curve as a "divide knot" defined by N. A'Campo in
the context of singularity theory of complex curves. For each knot given by
Berge's parameters, the corresponding plane curve is constructed. The surgery
coefficients are also considered. Such presentations support us to study each
knot itself, and the relationship among the knots in the set of lens space
surgeries.


title: Visibility of graphene flakes on a dielectric substrate

abstract:
  We model the optical visibility of monolayer and bilayer graphene deposited
on a silicon/silicon oxide substrate or thermally annealed on the surface of
silicon carbide. We consider reflection and transmission setups, and find that
visibility is strongest in reflection reaching the optimum conditions when the
bare substrate transmits light resonantly. In the optical range of frequencies
a bilayer is approximately twice as visible as a monolayer thereby making the
two types of graphene distinguishable from each other.


title: Shear-rate dependent transport coefficients for inelastic Maxwell models

abstract:
  The Boltzmann equation for d-dimensional inelastic Maxwell models is
considered to analyze transport properties in spatially inhomogeneous states
close to the simple shear flow. A normal solution is obtained via a
Chapman--Enskog--like expansion around a local shear flow distribution f^{(0)}
that retains all the hydrodynamic orders in the shear rate. The constitutive
equations for the heat and momentum fluxes are obtained to first order in the
deviations of the hydrodynamic field gradients from their values in the
reference state and the corresponding generalized transport coefficients are
{\em exactly} determined in terms of the coefficient of restitution \alpha and
the shear rate a. Since f^{(0)} applies for arbitrary values of the shear rate
and is not restricted to weak dissipation, the transport coefficients turn out
to be nonlinear functions of both parameters a and \alpha. A comparison with
previous results obtained for inelastic hard spheres from a kinetic model of
the Boltzmann equation is also carried out.


title:
Modeling of torsion stress giant magnetoimpedance in amorphous wires
  with negative magnetostriction

abstract:
  A model describing the influence of torsion stress on the giant
magnetoimpedance in amorphous wires with negative magnetostriction is proposed.
The wire impedance is found by means of the solution of Maxwell equations
together with the Landau-Lifshitz equation, assuming a simplified spatial
distribution of the magnetoelastic anisotropy induced by the torsion stress.
The impedance is analyzed as a function of the external magnetic field, torsion
stress and frequency. It is shown that the magnetoimpedance ratio torsion
dependence has an asymmetric shape, with a sharp peak at some value of the
torsion stress. The calculated field and stress dependences of the impedance
are in qualitative agreement with results of the experimental study of the
torsion stress giant magnetoimpedance in Co-based amorphous wires.


title:
A new Determination of the Extragalactic Background of Diffuse Gamma
  Rays taking into account Dark Matter Annihilation

abstract:
  The extragalactic background (EGB) of diffuse gamma rays can be determined by
subtracting the Galactic contribution from the data. This requires a Galactic
model (GM) and we include for the first time the contribution of dark matter
annihilation (DMA), which was previously proposed as an explanation for the
EGRET excess of diffuse Galactic gamma rays above 1 GeV.
  In this paper it is shown that the newly determined EGB shows a
characteristic high energy bump on top of a steeply falling soft contribution.
The bump is shown to be compatible with a contribution from an extragalactic
DMA signal from weakly interacting massive particles (WIMPs) with a mass
between 50 and 100 GeV in agreement with the EGRET excess of the Galactic
diffuse gamma rays and in disagreement with earlier analysis. The remaining
soft contribution of the EGB is shown to resemble the spectra of the observed
point sources in our Galaxy.


title:
Temperature dependence of coherent oscillations in Josephson phase
  qubits

abstract:
  We experimentally investigate the temperature dependence of Rabi oscillations
and Ramsey fringes in superconducting phase qubits driven by microwave pulses.
In a wide range of temperatures, we find that both the decay time and the
amplitude of these coherent oscillations remain nearly unaffected by thermal
fluctuations. The oscillations are observed well above the crossover
temperature from thermally activated escape to quantum tunneling for undriven
qubits. In the two-level limit, coherent qubit response rapidly vanishes as
soon as the energy of thermal fluctuations kT becomes larger than the energy
level spacing of the qubit. Our observations shed new light on the origin of
decoherence in superconducting qubits. The experimental data suggest that,
without degrading already achieved coherence times, phase qubits can be
operated at temperatures much higher than those reported till now.


title:
Quiet Sun magnetic fields from space-borne observations: simulating
  Hinode's case

abstract:
  We examine whether or not it is possible to derive the field strength
distribution of quiet Sun internetwork regions from very high spatial
resolution polarimetric observations in the visible. In particular, we consider
the case of the spectropolarimeter attached to the Solar Optical Telescope
aboard Hinode. Radiative magneto-convection simulations are used to synthesize
the four Stokes profiles of the \ion{Fe}{1} 630.2 nm lines. Once the profiles
are degraded to a spatial resolution of 0\farcs32 and added noise, we infer the
atmospheric parameters by means of Milne-Eddington inversions. The comparison
of the derived values with the real ones indicates that the visible lines yield
correct internetwork field strengths and magnetic fluxes, with uncertainties
smaller than $\sim$150 G, when a stray light contamination factor is included
in the inversion. Contrary to the results of ground-based observations at
1\arcsec, weak fields are retrieved wherever the field is weak in the
simulation.


title:
Collective Oscillations in Trapped Bose-Einstein Condensed Gases in the
  Presence of Weak Disorder

abstract:
  The influence of a weak random potential on the collective modes of a trapped
interacting Bose-Einstein condensate at zero temperature is calculated in the
limit when the correlation length of the disorder is smaller than the healing
length of the superfluid. The problem is solved in the Thomas-Fermi limit by
generalizing the superfluid hydrodynamic equations to allow for the presence of
weak disorder. We find that the disorder-induced frequency-shifts of the
low-energy excitations can be of the same order of magnitude as the beyond
mean-field corrections in the normal interaction recently observed
experimentally.