title: Isolated OB Associations in Stripped HI Gas Clouds

abstract:
  HST ACS/HRC images in UV (F250W), V (F555W), and I (F814W) resolve three
isolated OB associations that lie up to 30 kpc from the stellar disk of the S0
galaxy NGC 1533. Previous narrow-band Halpha imaging and optical spectroscopy
showed these objects as unresolved intergalactic HII regions having Halpha
luminosities consistent with single early-type O stars. These young stars lie
in stripped HI gas with column densities ranging from 1.5 - 2.5 * 10^20 cm^-2
and velocity dispersions near 30 km s^-1. Using the HST broadband colors and
magnitudes along with previously-determined Halpha luminosities, we place
limits on the masses and ages of each association, considering the importance
of stochastic effects for faint (M_V >-8) stellar populations. The upper limits
to their stellar masses range from 600 M_sun to 7000 M_sun, and ages range from
2 - 6 Myrs. This analysis includes an updated calculation of the conversion
factor between the ionizing luminosity and the total number of main sequence O
stars contained within an HII region. The photometric properties and sizes of
the isolated associations and other objects in the HRC fields are consistent
with those of Galactic stellar associations, open clusters and/or single O and
B stars. We interpret the age-size sequence of associations and clustered field
objects as an indication that these isolated associations are most likely
rapidly dispersing. Furthermore, we consider the possibility that these
isolated associations represent the first generation of stars in the HI ring
surrounding NGC 1533. This work suggests star formation in the unique
environment of a galaxy's outermost gaseous regions proceeds similarly to that
within the Galactic disk and that star formation in tidal debris may be
responsible for building up a younger halo component.


title:
Optical afterglow luminosities in the Swift epoch: confirming clustering
  and bimodality

abstract:
  We show that Gamma Ray Bursts (GRBs) of known redshift and rest frame optical
extinction detected by the Swift satellite fully confirm earlier results
concerning the distribution of the optical afterglow luminosity at 12 hours
after trigger (rest frame time). This distribution is bimodal and relatively
narrow, especially for the high luminosity branch. This is intriguing, given
that Swift GRBs have, on average, a redshift larger than pre-Swift ones, and is
unexpected in the common scenario explaining the GRB afterglow. We investigate
if the observed distribution can be the result of selection effects affecting a
unimodal parent luminosity distribution, and find that either the distribution
is intrinsically bimodal, or most (60 per cent) of the bursts are absorbed by a
substantial amount of grey dust. In both cases we suggest that most dark bursts
should belong to the underluminous optical family.


title:
XI Solomon Lefschetz Memorial Lecture Series: Hodge structures in
  non-commutative geometry. (Notes by Ernesto Lupercio)

abstract:
  Traditionally, Hodge structures are associated with complex projective
varieties. In my expository lectures I discussed a non-commutative
generalization of Hodge structures in deformation quantization and in derived
algebraic geometry.


title:
The Persistence of Memory, or How the X-Ray Spectrum of SNR 0509-67.5
  Reveals the Brightness of its Parent Type Ia Supernova

abstract:
  We examine the dynamics and X-ray spectrum of the young Type Ia supernova
remnant 0509-67.5 in the context of the recent results obtained from the
optical spectroscopy of its light echo. Our goal is to estimate the kinetic
energy of the supernova explosion using Chandra and XMM-Newton observations of
the supernova remnant, thus placing the birth event of 0509-67.5 in the
sequence of dim to bright Type Ia supernovae. We base our analysis on a
standard grid of one-dimensional delayed detonation explosion models, together
with hydrodynamic and X-ray spectral calculations of the supernova remnant
evolution. From the remnant dynamics and the properties of the O, Si, S, and Fe
emission in its X-ray spectrum we conclude that 0509-67.5 was originated ~400
years ago by a bright, highly energetic Type Ia explosion similar to SN 1991T.
Our best model has a kinetic energy of 1.4x10E51 erg and synthesizes 0.97 Msun
of 56Ni. These results are in excellent agreement with the age estimate and
spectroscopy from the light echo. We have thus established the first connection
between a Type Ia supernova and its supernova remnant based on a detailed
quantitative analysis of both objects.


title:
Spectral Identification of an Ancient Supernova using Light Echoes in
  the LMC

abstract:
  We report the successful identification of the type of the supernova
responsible for the supernova remnant SNR 0509-675 in the Large Magellanic
Cloud (LMC) using Gemini spectra of surrounding light echoes. The ability to
classify outbursts associated with centuries-old remnants provides a new window
into several aspects of supernova research and is likely to be successful in
providing new constraints on additional LMC supernovae as well as their
historical counterparts in the Milky Way Galaxy (MWG). The combined spectrum of
echo light from SNR 0509-675 shows broad emission and absorption lines
consistent with a supernova (SN) spectrum. We create a spectral library
consisting of 26 SNe Ia and 6 SN Ib/c that are time-integrated, dust-scattered
by LMC dust, and reddened by the LMC and MWG. We fit these SN templates to the
observed light echo spectrum using $\chi^2$ minimization as well as correlation
techniques, and we find that overluminous 91T-like SNe Ia with $\dm15<0.9$
match the observed spectrum best.


title: Gas and Dust Emission at the Outer Edge of Protoplanetary Disks

abstract:
  We investigate the apparent discrepancy between gas and dust outer radii
derived from millimeter observations of protoplanetary disks. Using 230 and 345
GHz continuum and CO J=3-2 data from the Submillimeter Array for four nearby
disk systems (HD 163296, TW Hydrae, GM Aurigae, and MWC 480), we examine models
of circumstellar disk structure and the effects of their treatment of the outer
disk edge. We show that for these disks, models described by power laws in
surface density and temperature that are truncated at an outer radius are
incapable of reproducing both the gas and dust emission simultaneously: the
outer radius derived from the dust continuum emission is always significantly
smaller than the extent of the molecular gas disk traced by CO emission.
However, a simple model motivated by similarity solutions of the time evolution
of accretion disks that includes a tapered exponential edge in the surface
density distribution (and the same number of free parameters) does much better
at reproducing both the gas and dust emission. While this analysis does not
rule out the disparate radii implied by the truncated power-law models, a
realistic alternative disk model, grounded in the physics of accretion,
provides a consistent picture for the extent of both the gas and dust.


title: Tidal debris in elliptical galaxies as tracers of mergers with disks

abstract:
  We use a set of high-resolution N-body simulations of binary galaxy mergers
to show that the morphologies of the tidal features that are seen around a
large fraction of nearby, massive ellipticals in the field, cannot be
reproduced by equal-mass dissipationless mergers; rather, they are well
explained by the accretion of disk-dominated galaxies. In particular, the arm-
and looplike morphologies of the observed tidal debris can only be produced by
the kinematically cold material of the disk components of the accreted
galaxies. The tidal features that arise from such "cold-accretion" events onto
a massive elliptical are visible for significantly longer timescales than the
features produced by elliptical-elliptical mergers (about 1-2 Gyr vs. a few
hundred million years). Mass ratios of the order of 1:10 between the accreting
elliptical and the accreted disk are sufficient to match the brightness of the
observed debris. Furthermore, stellar population synthesis models and simple
order-of-magnitude calculations indicate that the colors of the tidal features
generated in such minor cold-accretion events are relatively red, in agreement
with the observations. The minor cold-accretion events that explain the
presence, brightness, and structural and color properties of the tidal debris
cause only a modest mass and luminosity increase in the accreting massive
elliptical. These results, coupled with the relative statistical frequencies of
disk- and bulge-dominated galaxies in the field, suggest that massive
ellipticals assemble most of their mass well before their tidal debris forms
through the accretion of relatively little, kinematically cold material rather
than in very recent, dissipationless major mergers.


title: Transverse NMR relaxation in magnetically heterogeneous media

abstract:
  We consider the NMR signal from a permeable medium with a heterogeneous
Larmor frequency component that varies on a scale comparable to the
spin-carrier diffusion length. We focus on the mesoscopic part of the
transverse relaxation, that occurs due to dispersion of precession phases of
spins accumulated during diffusive motion. By relating the spectral lineshape
to correlation functions of the spatially varying Larmor frequency, we
demonstrate how the correlation length and the variance of the Larmor frequency
distribution can be determined from the NMR spectrum. We corroborate our
results by numerical simulations, and apply them to quantify human blood
spectra.


title: A Petrov type I and generically asymmetric rotating dust family

abstract:
  The general line element corresponding to the family of algebraically
general, gravito-electric, expanding, rotating dust models with one
functionally independent zero-order Riemann invariant is constructed. The
isometry group is at most one-dimensional but generically trivial. It is shown
that the asymmetric solutions with constant ratio of energy density and
vorticity amplitude provide first examples of Petrov type I space-times for
which the Karlhede classification requires the computation of the third
covariant derivative of the Riemann tensor.


title: Mode-Locking in Driven Disordered Systems as a Boundary-Value Problem

abstract:
  We study mode-locking in disordered media as a boundary-value problem.
Focusing on the simplest class of mode-locking models which consists of a
single driven overdamped degree-of-freedom, we develop an analytical method to
obtain the shape of the Arnol'd tongues in the regime of low ac-driving
amplitude or high ac-driving frequency. The method is exact for a scalloped
pinning potential and easily adapted to other pinning potentials. It is
complementary to the analysis based on the well-known Shapiro's argument that
holds in the perturbative regime of large driving amplitudes or low driving
frequency, where the effect of pinning is weak.


title:
Connecting Far-Infrared and Radio Morphologies of Disk Galaxies:
  Cosmic-Ray Electron Diffusion After Star Formation Episodes

abstract:
  We present results on the interstellar medium (ISM) properties of 29 galaxies
based on a comparison of {\it Spitzer} far-infrared and Westerbork Synthesis
Radio Telescope radio continuum imagery. Of these 29 galaxies, 18 are close
enough to resolve at $\la$1 kpc scales at 70 $\micron$ and 22 cm. We extend the
\citet{ejm06a,ejm06b} approach of smoothing infrared images to approximate
cosmic-ray (CR) electron spreading and thus largely reproduce the appearance of
radio images. Using a wavelet analysis we decompose each 70 $\micron$ image
into one component containing the star-forming {\it structures} and a second
one for the diffuse {\it disk}. The components are smoothed separately, and
their combination compared to a free-free corrected 22 cm radio image; the
scale-lengths are then varied to best match the radio and smoothed infrared
images. We find that late-type spirals having high amounts of ongoing star
formation benefit most from the two-component method. We also find that the
disk component dominates for galaxies having low star formation activity,
whereas the structure component dominates at high star formation activity. We
propose that this result arises from an age effect rather than from differences
in CR electron diffusion due to varying ISM parameters. The bulk of the CR
electron population in actively star-forming galaxies is significantly younger
than that in less active galaxies due to recent episodes of enhanced star
formation; these galaxies are observed within $\sim10^{8}$ yr since the onset
of the most recent star formation episode. The sample irregulars have
anomalously low best-fit scale-lengths for their surface brightnesses compared
to the rest of the sample spirals which we attribute to enhanced CR electron
escape.


title:
Cold gas & mergers: fundamental difference in HI properties of different
  types of radio galaxies?

abstract:
  We present results of a study of large-scale neutral hydrogen (HI) gas in
nearby radio galaxies. We find that the early-type host galaxies of different
types of radio sources (compact, FR-I and FR-II) appear to contain
fundamentally different large-scale HI properties: enormous regular rotating
disks and rings are present around the host galaxies of a significant fraction
of low power compact radio sources, while no large-scale HI is detected in low
power, edge-darkened FR-I radio galaxies. Preliminary results of a study of
nearby powerful, edge-brightened FR-II radio galaxies show that these systems
generally contain significant amounts of large-scale HI, often distributed in
tail- or bridge-like structures, indicative of a recent galaxy merger or
collision. Our results suggest that different types of radio galaxies may have
a different formation history, which could be related to a difference in the
triggering mechanism of the radio source. If confirmed by larger studies with
the next generation radio telescopes, this would be in agreement with previous
optical studies that suggest that powerful FR-II radio sources are likely
triggered by galaxy mergers and collisions, while the lower power FR-I sources
are fed in other ways (e.g. through the accretion of hot IGM). The giant HI
disks/rings associated with some compact sources could - at least in some cases
- be the relics of much more advanced mergers.


title: The gravitational path integral and trace of the diffeomorphisms

abstract:
  I give a resolution of the conformal mode divergence in the Euclidean
gravitational path-integral by isolating the trace of the diffeomorphisms and
its contribution to the Faddeev-Popov measure.


title: Self-organization of a Bose-Einstein condensate in an optical cavity

abstract:
  The spatial self-organization of a Bose-Einstein condensate (BEC) in a
high-finesse linear optical cavity is discussed. The condensate atoms are
laser-driven from the side and scatter photons into the cavity. Above a
critical pump intensity the homogeneous condensate evolves into a stable
pattern bound by the cavity field. The transition point is determined
analytically from a mean-field theory. We calculate the lowest lying Bogoliubov
excitations of the coupled BEC-cavity system and the quantum depletion due to
the atom-field coupling.


title:
Navy Prototype Optical Interferometer Imaging of Line Emission Regions
  of beta Lyrae Using Differential Phase Referencing

abstract:
  We present the results of an experiment to image the interacting binary star
beta Lyrae with data from the Navy Prototype Optical Interferometer (NPOI),
using a differential phase technique to correct for the effects of the
instrument and atmosphere on the interferometer phases. We take advantage of
the fact that the visual primary of beta Lyrae and the visibility calibrator we
used are both nearly unresolved and nearly centrally symmetric, and
consequently have interferometric phases near zero. We used this property to
detect and correct for the effects of the instrument and atmosphere on the
phases of beta Lyrae and to obtain differential phases in the channel
containing the Halpha emission line. Combining the Halpha-channel phases with
information about the line strength, we recovered complex visibilities and
imaged the Halpha emission using standard radio interferometry methods. We find
that the results from our differential phase technique are consistent with
those obtained from a more-standard analysis using squared visibilities
(V^2's). Our images show the position of the Halpha emitting regions relative
to the continuum photocenter as a function of orbital phase and indicate that
the major axis of the orbit is oriented along p.a.=248.8+/-1.7 deg. The orbit
is smaller than previously predicted, a discrepancy that can be alleviated if
we assume that the system is at a larger distance from us, or that the
contribution of the stellar continuum to the Halpha channel is larger than
estimated. Finally, we also detected a differential phase signal in the
channels containing HeI emission lines at 587.6 and 706.5nm, with orbital
behavior different from that of the Halpha, indicating that it originates from
a different part of this interacting system.


title: Effective structure theorems for symplectic spaces via height

abstract:
  Given a $2k$-dimensional symplectic space $(Z,F)$ in $N$ variables, $1 < 2k
\leq N$, over a global field $K$, we prove the existence of a symplectic basis
for $(Z,F)$ of bounded height. This can be viewed as a version of Siegel's
lemma for a symplectic space. As corollaries of our main result, we prove the
existence of a small-height decomposition of $(Z,F)$ into hyperbolic planes, as
well as the existence of two generating flags of totally isotropic subspaces.
These present analogues of known results for quadratic spaces. A distinctive
feature of our argument is that it works simultaneously for essentially any
field with a product formula, algebraically closed or not. In fact, we prove an
even more general version of these statements, where canonical height is
replaced with twisted height. All bounds on height are explicit.


title:
Source Code Protection for Applications Written in Microsoft Excel and
  Google Spreadsheet

abstract:
  Spreadsheets are used to develop application software that is distributed to
users. Unfortunately, the users often have the ability to change the
programming statements ("source code") of the spreadsheet application. This
causes a host of problems. By critically examining the suitability of
spreadsheet computer programming languages for application development, six
"application development features" are identified, with source code protection
being the most important. We investigate the status of these features and
discuss how they might be implemented in the dominant Microsoft Excel
spreadsheet and in the new Google Spreadsheet. Although Google Spreadsheet
currently provides no source code control, its web-centric delivery model
offers technical advantages for future provision of a rich set of features.
Excel has a number of tools that can be combined to provide "pretty good
protection" of source code, but weak passwords reduce its robustness. User
access to Excel source code must be considered a programmer choice rather than
an attribute of the spreadsheet.


title:
Spreadsheet Assurance by "Control Around" is a Viable Alternative to the
  Traditional Approach

abstract:
  The traditional approach to spreadsheet auditing generally consists of
auditing every distinct formula within a spreadsheet. Although tools are
developed to support auditors during this process, the approach is still very
time consuming and therefore relatively expensive. As an alternative to the
traditional "control through" approach, this paper discusses a "control around"
approach. Within the proposed approach not all distinct formulas are audited
separately, but the relationship between input data and output data of a
spreadsheet is audited through comparison with a shadow model developed in a
modelling language. Differences between the two models then imply possible
errors in the spreadsheet. This paper describes relevant issues regarding the
"control around" approach and the circumstances in which this approach is
preferred above a traditional spreadsheet audit approach.


title: Silicates in Ultra-Luminous Infrared Galaxies

abstract:
  We analyze the mid-infrared (MIR) spectra of ultraluminous infrared galaxies
(ULIRGs) observed with the Spitzer Space Telescope's Infrared Spectrograph.
Dust emission dominates the MIR spectra of ULIRGs, and the reprocessed
radiation that emerges is independent of the underlying heating spectrum.
Instead, the resulting emission depends sensitively on the geometric
distribution of the dust, which we diagnose with comparisons of numerical
simulations of radiative transfer. Quantifying the silicate emission and
absorption features that appear near 10 and 18um requires a reliable
determination of the continuum, and we demonstrate that including a measurement
of the continuum at intermediate wavelength (between the features) produces
accurate results at all optical depths. With high-quality spectra, we
successfully use the silicate features to constrain the dust chemistry. The
observations of the ULIRGs and local sightlines require dust that has a
relatively high 18/10um absorption ratio of the silicate features (around 0.5).
Specifically, the cold dust of Ossenkopf et al. (1992) is consistent with the
observations, while other dust models are not. We use the silicate feature
strengths to identify two families of ULIRGs, in which the dust distributions
are fundamentally different. Optical spectral classifications are related to
these families. In ULIRGs that harbor an active galactic nucleus, the
spectrally broad lines are detected only when the nuclear surroundings are
clumpy. In contrast, the sources of lower ionization optical spectra are deeply
embedded in smooth distributions of optically thick dust.


title: Non-Deterministic Communication Complexity of Regular Languages

abstract:
  In this thesis, we study the place of regular languages within the
communication complexity setting. In particular, we are interested in the
non-deterministic communication complexity of regular languages.
  We show that a regular language has either O(1) or Omega(log n)
non-deterministic complexity. We obtain several linear lower bound results
which cover a wide range of regular languages having linear non-deterministic
complexity. These lower bound results also imply a result in semigroup theory:
we obtain sufficient conditions for not being in the positive variety Pol(Com).
  To obtain our results, we use algebraic techniques. In the study of regular
languages, the algebraic point of view pioneered by Eilenberg (\cite{Eil74})
has led to many interesting results. Viewing a semigroup as a computational
device that recognizes languages has proven to be prolific from both semigroup
theory and formal languages perspectives. In this thesis, we provide further
instances of such mutualism.


title:
Off-center impurities in alkali halides: reorientation, electric
  polarization and binding to F center. V. Temperature-dependent electrostatic
  polarizabilities

abstract:
  We derive and discuss expressions for the temperature-dependent electrostatic
polarizabilities of off-center ions holding good under various experimental
conditions. At low temperatures and electric-field strengths, all of them
reasonably reduce to values characteristic of phonon-coupled two-level systems.
Prospects for further studies of the dispersive coupling are also considered.


title:
Chandra X-ray Grating Spectrometry of Eta Carinae near X-ray Minimum: I.
  Variability of the Sulfur and Silicon Emission Lines

abstract:
  We report on variations in important X-ray emission lines in a series of
Chandra grating spectra of the supermassive colliding wind binary star Eta
Carinae, including key phases around the X-ray minimum/periastron passage in
2003.5. The X-rays arise from the collision of the slow, dense wind of Eta Car
with the fast, low-density wind of an otherwise hidden companion star. The
X-ray emission lines provide the only direct measure of the flow dynamics of
the companion's wind along the wind-wind collision zone. We concentrate here on
the silicon and sulfur lines, which are the strongest and best resolved lines
in the X-ray spectra. Most of the line profiles can be adequately fit with
symmetric Gaussians with little significant skewness. Both the silicon and
sulfur lines show significant velocity shifts and correlated increases in line
widths through the observations. The R = forbidden-to-intercombination ratio
from the Si XIII and S XV triplets is near or above the low-density limit in
all observations, suggesting that the line-forming region is >1.6 stellar radii
from the companion star. We show that simple geometrical models cannot
simultaneously fit both the observed centroid variations and changes in line
width as a function of phase. We show that the observed profiles can be fitted
with synthetic profiles with a reasonable model of the emissivity along the
wind-wind collision boundary. We use this analysis to help constrain the line
formation region as a function of orbital phase, and the orbital geometry.


title: X-rays from magnetically channeled winds of OB stars

abstract:
  OB stars with strong radiation-driven stellar winds and large-scale magnetic
fields generate strong and hard X-ray emission via the Magnetically Channeled
Wind Shock (MCWS) mechanism. In this brief paper, I describe four separate
X-ray diagnostics of the MCWS mechanism in OB stars, with applications to the
prototype young O star, theta-1 Ori C.


title: A Multiwavelength Analysis of the Halo Planetary Nebula DdDm-1

abstract:
  We present new HST optical imagery as well as new UV and IR spectroscopic
data obtained with the Hubble and Spitzer Space Telescopes, respectively, of
the halo planetary nebula DdDm-1. For the first time we present a resolved
image of this object which indicates that the morphology of DdDm-1 can be
described as two orthogonal elliptical components in the central part
surrounded by an extended halo. The extent of the emission is somewhat larger
than was previously reported in the literature. We combine the spectral data
with our own previously published optical measurements to derive nebular
abundances of He, C, N, O, Ne, Si, S, Cl, Ar, and Fe. Our abundance
determinations include the use of the newly developed program ELSA for
obtaining abundances directly from emission line strengths along with detailed
photoionization models to render a robust set of abundances for this object.
The metallicity, as gauged by oxygen, is found to be 0.46 dex below the solar
value, confirming DdDm-1's status as a halo PN. In addition, we find that Si
and Fe are markedly underabundant, suggesting their depletion onto dust. The
very low (but uncertain) C/O ratio suggests that the chemistry of the nebula
should be consistent with an oxygen-rich environment. We find that the sulfur
abundance of DdDm-1 is only slightly below the value expected based upon the
normal lockstep behavior between S and O observed in H II regions and blue
compact galaxies. The central star effective temperature and luminosity are
estimated to be 55,000 K and 1000 solar luminosities, respectively, implying an
initial progenitor mass of <1 solar masses. Finally, we report on a new radial
velocity determination from echelle observations.


title: Chiral Algebras of (0,2) Sigma Models: Beyond Perturbation Theory

abstract:
  We explore the nonperturbative aspects of the chiral algebras of N = (0,2)
sigma models, which perturbatively are intimately related to the theory of
chiral differential operators (CDOs). The grading by charge and scaling
dimension is anomalous if the first Chern class of the target space is nonzero.
This has some nontrivial consequences for the chiral algebra. As an example, we
study the case where the target space is CP^1, and show that worldsheet
instantons trivialize the chiral algebra entirely. Consequently, supersymmetry
is spontaneously broken in this model. We then turn to a closer look at the
supersymmetry breaking from the viewpoint of Morse theory on loop space. We
find that instantons interpolate between pairs of perturbative supersymmetric
states with different fermionic numbers, hence lifting them out of the
supersymmetric spectrum. Our results reveal that a "quantum" deformation of the
geometry of the target space leads to a trivialization of the kernels of
certain twisted Dirac operators on CP^1.


title:
Enhanced thermal stability and spin-lattice relaxation rate of N@C60
  inside carbon nanotubes

abstract:
  We studied the temperature stability of the endohedral fullerene molecule,
N@C60, inside single-wall carbon nanotubes using electron spin resonance
spectroscopy. We found that the nitrogen escapes at higher temperatures in the
encapsulated material as compared to its pristine, crystalline form. The
temperature dependent spin-lattice relaxation time, T_1, of the encapsulated
molecule is significantly shorter than that of the crystalline material, which
is explained by the interaction of the nitrogen spin with the conduction
electrons of the nanotubes.


title: Two-Dimensional Thermofield Bosonization II: Massive Fermions

abstract:
  We consider the perturbative computation of the N-point function of chiral
densities of massive free fermions at finite temperature within the thermofield
dynamics approach. The infinite series in the mass parameter for the N-point
functions are computed in the fermionic formulation and compared with the
corresponding perturbative series in the interaction parameter in the bosonized
thermofield formulation. Thereby we establish in thermofield dynamics the
formal equivalence of the massive free fermion theory with the sine-Gordon
thermofield model for a particular value of the sine-Gordon parameter. We
extend the thermofield bosonization to include the massive Thirring model.


title: The zero-energy Landau levels in graphene as BPS-saturated states

abstract:
  This paper has been withdrawn by the author, due to the crucial mistake of
the discussion in Sec IV.


title: Cryptanalysis of Anshel-Anshel-Goldfeld-Lemieux key agreement protocol

abstract:
  The Anshel-Anshel-Goldfeld-Lemieux (abbreviated AAGL) key agreement protocol
is proposed to be used on low-cost platforms which constraint the use of
computational resources. The core of the protocol is the concept of an
Algebraic Eraser (abbreviated AE) which is claimed to be a suitable primitive
for use within lightweight cryptography. The AE primitive is based on a new and
ingenious idea of using an action of a semidirect product on a (semi)group to
obscure involved algebraic structures. The underlying motivation for AAGL
protocol is the need to secure networks which deploy Radio Frequency
Identification (RFID) tags used for identification, authentication, tracing and
point-of-sale applications.
  In this paper we revisit the computational problem on which AE relies and
heuristically analyze its hardness. We show that for proposed parameter values
it is impossible to instantiate the secure protocol. To be more precise, in
100% of randomly generated instances of the protocol we were able to find a
secret conjugator z generated by TTP algorithm (part of AAGL protocol).


title:
Long-range magnetic order and spin-lattice coupling in the delafossite
  CuFeO2

abstract:
  The electronic and magnetic properties of the delafossite CuFeO2 are
investigated by means of electronic structure calculations. They are performed
using density functional theory in the generalized gradient approximation as
well as the new full-potential augmented spherical wave method. The
calculations reveal three different spin states at the iron sites. Taking into
account the correct crystal structure, we find long-range antiferromagnetic
ordering in agreement with experiment. Contrasting previous work, our
calculations show that non-local exchange interactions lead to a semiconducting
ground state.


title:
Exciton Gas Compression and Metallic Condensation in a Single
  Semiconductor Quantum Wire

abstract:
  We study the metal-insulator transition in individual self-assembled quantum
wires and report optical evidences of metallic liquid condensation at low
temperatures. Firstly, we observe that the temperature and power dependence of
the single nanowire photoluminescence follow the evolution expected for an
electron-hole liquid in one dimension. Secondly, we find novel spectral
features that suggest that in this situation the expanding liquid condensate
compresses the exciton gas in real space. Finally, we estimate the critical
density and critical temperature of the phase transition diagram at
$n_c\sim1\times10^5$ cm$^{-1}$ and $T_c\sim35$ K, respectively.


title: Anomaly-Mediation and Sequestering from a Higher-Dimensional viewpoint

abstract:
  We study a five-dimensional supergravity model with boundary-localized
visible sector exhibiting anomaly-mediated supersymmetry breaking, in which the
central requirements of sequestering and radius stabilization are achieved
perturbatively. This makes it possible to understand these various mechanisms
in a more integrated and transparent fashion, mostly from the
higher-dimensional viewpoint. Local supersymmetry, in the presence of visible
sector quantum effects, is enforced by the formalism of the five-dimensional
superconformal tensor calculus. The construction results in only mild warping,
which allows a natural supersymmetry-breaking mediation mechanism of (finite)
boundary-to-boundary gravity loops to co-dominate with anomaly-mediation,
thereby solving the latter's tachyonic slepton problem. We make the non-trivial
check that this can occur while dangerous loops of stabilizing fields remain
highly suppressed. Our discussion is a well-controlled starting point for
considering other generalizations of anomaly-mediation, or for string theory
realizations.


title: Information Width

abstract:
  Kolmogorov argued that the concept of information exists also in problems
with no underlying stochastic model (as Shannon's information representation)
for instance, the information contained in an algorithm or in the genome. He
introduced a combinatorial notion of entropy and information $I(x:\sy)$
conveyed by a binary string $x$ about the unknown value of a variable $\sy$.
The current paper poses the following questions: what is the relationship
between the information conveyed by $x$ about $\sy$ to the description
complexity of $x$ ? is there a notion of cost of information ? are there limits
on how efficient $x$ conveys information ?
  To answer these questions Kolmogorov's definition is extended and a new
concept termed {\em information width} which is similar to $n$-widths in
approximation theory is introduced. Information of any input source, e.g.,
sample-based, general side-information or a hybrid of both can be evaluated by
a single common formula. An application to the space of binary functions is
considered.


title: Finite-Q^2 corrections to parity-violating DIS

abstract:
  Parity-violating deep inelastic scattering (PVDIS) has been proposed as an
important new tool to extract the flavor and isospin dependence of parton
distributions in the nucleon. We discuss finite-Q^2 effects in PVDIS
asymmetries arising from subleading kinematical corrections and longitudinal
contributions to the photon-Z interference. For the proton, these need to be
accounted for in order to accurately extract the d/u ratio at large x; for the
deuteron they are important to consider when searching for evidence of charge
symmetry violation in parton distributions or signals for physics beyond the
standard model. We further explore the dependence of PVDIS asymmetries for
polarized targets on the u and d helicity distributions at large x.


title:
Minimal duality breaking in the Kallen-Lehman approach to 3D Ising
  model: a numerical test

abstract:
  A Kallen-Lehman approach to 3D Ising model is analyzed numerically both at
low and high temperature. It is shown that, even assuming a minimal duality
breaking, one can fix three parameters of the model to get a very good
agreement with the MonteCarlo results at high temperatures. With the same
parameters the agreement is satisfactory both at low and near critical
temperatures. How to improve the agreement with MonteCarlo results by
introducing a more general duality breaking is shortly discussed.

categories: cond-mat.stat-mech gr-qc hep-lat hep-ph hep-th


title: Holography and Emergent 4D Gravity

abstract:
  I review recent work toward constructing, via five-dimensional holographic
duals, four-dimensional theories in which spin-2 states (gravitons) are
emergent. The basic idea is to extend to gravity model-building the
applications of holographic duality to phenomenology construction.


title: On the Complexity of Binary Samples

abstract:
  Consider a class $\mH$ of binary functions $h: X\to\{-1, +1\}$ on a finite
interval $X=[0, B]\subset \Real$. Define the {\em sample width} of $h$ on a
finite subset (a sample) $S\subset X$ as $\w_S(h) \equiv \min_{x\in S}
|\w_h(x)|$, where $\w_h(x) = h(x) \max\{a\geq 0: h(z)=h(x), x-a\leq z\leq
x+a\}$. Let $\mathbb{S}_\ell$ be the space of all samples in $X$ of cardinality
$\ell$ and consider sets of wide samples, i.e., {\em hypersets} which are
defined as $A_{\beta, h} = \{S\in \mathbb{S}_\ell: \w_{S}(h) \geq \beta\}$.
Through an application of the Sauer-Shelah result on the density of sets an
upper estimate is obtained on the growth function (or trace) of the class
$\{A_{\beta, h}: h\in\mH\}$, $\beta>0$, i.e., on the number of possible
dichotomies obtained by intersecting all hypersets with a fixed collection of
samples $S\in\mathbb{S}_\ell$ of cardinality $m$. The estimate is
$2\sum_{i=0}^{2\lfloor B/(2\beta)\rfloor}{m-\ell\choose i}$.


title:
Is a binary fraction-age relation responsible for the lack of EHB
  binaries in globular clusters?

abstract:
  The recently-discovered lack of close binaries, among extreme horizontal
branch (EHB) stars in Galactic globular clusters, has thus far constituted a
major puzzle, in view of the fact that blue subdwarf stars - the field
counterparts of cluster EHB stars - are well-known to present a high binary
fraction. In this Letter, we provide new results that confirm the lack of close
EHB binaries in globular clusters, and present a first scenario to explain the
difference between field and cluster EHB stars. First, in order to confirm that
the lack of EHB binaries in globular clusters is a statistically robust result,
we undertook a new analysis of 145 horizontal branch stars in NGC6752, out of
which forty-one belong to the EHB. To search for radial-velocity variations as
a function of time, we repeated high-resolution (R=18500) spectroscopy of all
stars, four times during a single night of observations. We detected a single,
hot (25000 K), radial-velocity variable star as a close-binary candidate. From
these results, we estimate an upper-limit for the close (period P < 5 day)
binary fraction f among NGC6752 EHB stars of 16% (95% confidence level), with
the most probable value being f=4%. Thus our results clearly confirm the lack
of close binaries among the hot HB stars in this cluster. We suggest that the
confirmed discrepancy between the binary fractions for field and cluster EHB
stars is the consequence of an f-age relation, with close binaries being more
likely in the case of younger systems. We analyze theoretical and observational
results available in the literature, which support this scenario. If so, an age
difference between the EHB progenitors in the field and in clusters, the former
being younger (on average) by up to several Gyr, would naturally account for
the startling differences in binary fraction between the two populations.


title:
Control of Four-Level Quantum Coherence via Discrete Spectral Shaping of
  an Optical Frequency Comb

abstract:
  We present an experiment demonstrating high-resolution coherent control of a
four-level atomic system in a closed (diamond) type configuration. A
femtosecond frequency comb is used to establish phase coherence between a pair
of two-photon transitions in cold Rb atoms. By controlling the spectral phase
of the frequency comb we demonstrate the optical phase sensitive response of
the diamond system. The high-resolution state selectivity of the comb is used
to demonstrate the importance of the signs of dipole moment matrix elements in
this type of closed-loop excitation. Finally, the pulse shape is optimized
resulting in a 256% increase in the two-photon transition rate by forcing
constructive interference between the mode pairs detuned from an intermediate
resonance.


title: Geometrization of electromagnetism in tetrad-spin-connection gravity

abstract:
  The metric-affine Lagrangian of Ponomarev and Obukhov for the unified
gravitational and electromagnetic field is linear in the Ricci scalar and
quadratic in the tensor of homothetic curvature. We apply to this Lagrangian
the variational principle with the tetrad and spin connection as dynamical
variables and show that, in this approach, the field equations are the
Einstein-Maxwell equations if we relate the electromagnetic potential to the
trace of the spin connection. We also show that, as in the Ponomarev-Obukhov
formulation, the generally covariant Dirac Lagrangian gives rise to the
standard spinor source for the Einstein-Maxwell equations, while the spinor
field obeys the nonlinear Heisenberg-Ivanenko equation with the electromagnetic
coupling. We generalize that formulation to spinors with arbitrary electric
charges.


title: Asymptotic behavior of global solutions of the $u_t=\Delta u + u^{p}$

abstract:
  We study the asymptotic behavior of nonnegative solutions of the semilinear
parabolic problem
  {u_t=\Delta u + u^{p}, x\in\mathbb{R}^{N}, t>0
  u(0)=u_{0}, x\in\mathbb{R}^{N}, t=0.
  It is known that the nonnegative solution $u(t)$ of this problem blows up in
finite time for $1<p\leq 1+ 2/N$. Moreover, if $p> 1+ 2/N$ and the norm of
$u_{0}$ is small enough, the problem admits global solution. In this work, we
use the entropy method to obtain the decay rate of the global solution $u(t)$.


title: A composite gluino at the LHC

abstract:
  We investigate the decay of particles with the quantum numbers of the gluino.
Besides SUSY, such particles may be present in models where the Higgs and top
are composite. We find that such 'composite' gluinos have decay signatures
similar to those of gluinos in 'more minimal' SUSY type models. Though it is in
principle possible to distinguish the two scenarios, we find that it will be a
challenging task at the LHC. This puts into question the common lore that a
gluino is an obvious 'smoking-gun' signature of SUSY.


title: Constructing Seifert surfaces from n-bridge link projections

abstract:
  This paper presents a new algorithm "A" for constructing Seifert surfaces
from n-bridge projections of links. The algorithm produces minimal complexity
surfaces for large classes of braids and alternating links. In addition, we
consider a family of knots for which the canonical genus is strictly greater
than the genus, (g_c(K) > g(K)), and show that A builds surfaces realizing the
knot genus g(K). We also present a generalization of Seifert's algorithm which
may be used to construct surfaces representing arbitrary relative second
homology classes in a link complement.


title: GROND - a 7-channel imager

abstract:
  We describe the construction of GROND, a 7-channel imager, primarily designed
for rapid observations of gamma-ray burst afterglows. It allows simultaneous
imaging in the Sloan g'r'i'z' and near-infrared $JHK$ bands. GROND was
commissioned at the MPI/ESO 2.2m telescope at La Silla (Chile) in April 2007,
and first results of its performance and calibration are presented.


title:
Investigating the Potential of Test-Driven Development for Spreadsheet
  Engineering

abstract:
  It is widely documented that the absence of a structured approach to
spreadsheet engineering is a key factor in the high level of spreadsheet
errors. In this paper we propose and investigate the application of Test-Driven
Development to the creation of spreadsheets. Test-Driven Development is an
emerging development technique in software engineering that has been shown to
result in better quality software code. It has also been shown that this code
requires less testing and is easier to maintain. Through a pair of case studies
we demonstrate that Test-Driven Development can be applied to the development
of spreadsheets. We present the detail of these studies preceded by a clear
explanation of the technique and its application to spreadsheet engineering. A
supporting tool under development by the authors is also documented along with
proposed research to determine the effectiveness of the methodology and the
associated tool.


title: Radio spectral properties and the magnetic field of the SNR S147

abstract:
  (Abridged) S147 is a large faint shell-type supernova remnant (SNR). Its
remarkable spectral break at cm-wavelengths is an important physical property
to characterize the SNR evolution. However, the spectral break is based on
radio observations with limited precision. We made new radio continuum and
polarization observations of S147 at 11cm and at 6cm with the Effelsberg 100-m
telescope and the Urumqi 25-m telescope, respectively. These new data were
combined with published lower frequency data from the Effelsberg 100-m
telescope and very high frequency data from WMAP to investigate the spectral
turnover and polarization properties of S147. S147 consists of numerous
filaments embedded in diffuse emission. We found that the integrated flux
densities of S147 are 34.8+/-4.0 Jy at 11cm and 15.4+/-3.0Jy at 6cm. These new
measurements confirm the known spectral turnover at ~1.5GHz, which can be
entirely attributed to the diffuse emission component. The spectral index above
the turnover is -1.35+/-0.20. The filamentary emission component has a constant
spectral index over the entire wavelength range up to 40.7GHz of -0.35+/-0.15.
The weak polarized emission of S147 is at the same level as the ambient diffuse
Galactic polarization. The rotation measure of the eastern filamentary shell is
about -70 rad/m2. The filamentary and diffuse emission components of S147 have
different physical properties, which make S147 outstanding among shell type
SNRs.The weak polarization of S147 at 11cm and at 6cm can be attributed to a
section of the S147 shell showing a tangential magnetic field direction.


title:
Inelastic collisions of ultra-cold heteronuclear molecules in an optical
  trap

abstract:
  Ultra-cold RbCs molecules in high-lying vibrational levels of the
a$^3\Sigma^+$ ground electronic state are confined in an optical trap.
Inelastic collision rates of these molecules with both Rb and Cs atoms are
determined for individual vibrational levels, across an order of magnitude of
binding energies. A simple model for the collision process is shown to
accurately reproduce the observed scattering rates.


title: Outburst of a WZ Sge-type dwarf nova, AL Com in 2007

abstract:
  We report photometric observations of AL Com during its rare outburst in
2007. The light curve is reminiscent of its past superoutbursts in 1995 and
2001, except for the rebrightening phase after the main superoutburst. During
the rebrightening phase in 2007, we found clear modulations between
V=16.2-15.2. In conjunction with the lack of prominent superhumps in our
time-series observations, the modulations can most naturally be interpreted as
repetitive short rebrightenings with a cycle of 1-2 days. The rebrightening
characteristics in 2007 are different from those in 1995 and 2001. This
indicates that the type of rebrightenings in WZ Sge stars depends not on binary
parameters of objects, but on the mass-accretion process for each outburst.


title:
First Measurement of ZZ Production in ppbar Collisions at sqrt(s)=1.96
  TeV

abstract:
  We report the first measurement of the cross section for Z boson pair
production at a hadron collider. This result is based on a data sample
corresponding to 1.9 fb-1 of integrated luminosity from ppbar collisions at
sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron.
In the llll channel, we observe three ZZ candidates with an expected background
of 0.096^{+0.092}_{-0.063} events. In the llnunu channel, we use a
leading-order calculation of the relative ZZ and WW event probabilities to
discriminate between signal and background. In the combination of llll and
llnunu channels, we observe an excess of events with a probability of
$5.1\times 10^{-6}$ to be due to the expected background. This corresponds to a
significance of 4.4 standard deviations. The measured cross section is
sigma(ppbar -> ZZ) = 1.4^{+0.7}_{-0.6} (stat.+syst.) pb, consistent with the
standard model expectation.


title: Automatic Text Area Segmentation in Natural Images

abstract:
  We present a hierarchical method for segmenting text areas in natural images.
The method assumes that the text is written with a contrasting color on a more
or less uniform background. But no assumption is made regarding the language or
character set used to write the text. In particular, the text can contain
simple graphics or symbols. The key feature of our approach is that we first
concentrate on finding the background of the text, before testing whether there
is actually text on the background. Since uniform areas are easy to find in
natural images, and since text backgrounds define areas which contain "holes"
(where the text is written) we thus look for uniform areas containing "holes"
and label them as text backgrounds candidates. Each candidate area is then
further tested for the presence of text within its convex hull. We tested our
method on a database of 65 images including English and Urdu text. The method
correctly segmented all the text areas in 63 of these images, and in only 4 of
these were areas that do not contain text also segmented.


title: The Principal Element of a Frobenius Lie Algebra

abstract:
  We introduce the notion of the \textit{principal element} of a Frobenius Lie
algebra $\f$. The principal element corresponds to a choice of $F\in \f^*$ such
that $F[-,-]$ non-degenerate. In many natural instances, the principal element
is shown to be semisimple, and when associated to $\sl_n$, its eigenvalues are
integers and are independent of $F$. For certain ``small'' functionals $F$, a
simple construction is given which readily yields the principal element. When
applied to the first maximal parabolic subalgebra of $\sl_n$, the principal
element coincides with semisimple element of the principal three-dimensional
subalgebra. We also show that Frobenius algebras are stable under deformation.


title: Creation of Spiral Galaxies

abstract:
  The spiral galaxies, including our galaxy, are created by the
gravito-radiative forces generated by colliding black holes at the center of
quasars. The gravito-radiative force is predicted by Einstein's general
relativity. A quasar is assumed to have a circular disk of highly compressed
neutrons (ylem) orbiting around black holes. The collision of two black holes
at the center generates the gravito-radiative force, exerted on the ylem disk,
producing a pair of bars with 180 degree rotational symmetry. This pair of bars
develop into a pair of spiral arms, keeping the 180 degree rotational symmetry.
Therefore, the number of spiral arms must be even. Our Milky Way galaxy has two
pairs of arms, and has the 180 degree rotational symmetry, indicating that we
have had two galactic nuclear explosions. The theory proposed by Gamow and
others on the making of chemical elements fits into this theory. Thus, the age
of the Milky Way must be equal to or greater than the age of the earth, 4.5
billion yr. The spirality of the Milky Way galaxy is examined under this
assumption, and it is found that our galaxy was once about 10 times larger than
it is now, and has been shrinking during the last half of its life.


title: Meson and tetra-quark mixing

abstract:
  The mixing between q-qbar meson and qqbar-qqbar tetra-quark states is
examined within an effective QCD Coulomb gauge Hamiltonian model. Mixing matrix
elements of the Hamiltonian are computed and then diagonalized yielding an
improved prediction for the low-lying J^{PC} = 0^{+/- +}, 1^{--} isoscalar
spectra. Mixing effects were found significant for the scalar hadrons but not
for the 1^{--} states, which is consistent with the ideal mixing of vector
mesons. A perturbative assessment of the exact QCD kernel is also reported.


title:
Equidistribution of Dynamically Small Subvarieties over the Function
  Field of a Curve

abstract:
  For a projective variety X defined over a field K, there is a special class
of self-morphisms of X called algebraic dynamical systems. In this paper we
take K to be the function field of a smooth curve and prove that at each place
of K, subvarieties of X of dynamically small height are equidistributed on the
associated Berkovich analytic space. We carefully develop all of the arithmetic
intersection theory needed to state and prove this theorem, and we present
several applications on the non-Zariski density of preperiodic points and of
points of small height in field extensions of bounded degree.


title: The fixation probability of rare mutators in finite asexual populations

abstract:
  A mutator is an allele that increases the mutation rate throughout the genome
by disrupting some aspect of DNA replication or repair. Mutators that increase
the mutation rate by the order of 100 fold have been observed to spontaneously
emerge and achieve high frequencies in natural populations and in long-term
laboratory evolution experiments with \textit{E. coli}. In principle, the
fixation of mutator alleles is limited by (i) competition with mutations in
wild-type backgrounds, (ii) additional deleterious mutational load, and (iii)
random genetic drift. Using a multiple locus model and employing both
simulation and analytic methods, we investigate the effects of these three
factors on the fixation probability $P_{fix}$ of an initially rare mutator as a
function of population size $N$, beneficial and deleterious mutation rates, and
the strength of mutations $s$. Our diffusion based approximation for $P_{fix}$
successfully captures effects (ii) and (iii) when selection is fast compared to
mutation ($\mu/s \ll 1$). This enables us to predict the conditions under which
mutators will be evolutionarily favored. Surprisingly, our simulations show
that effect (i) is typically small for strong-effect mutators. Our results
agree semi-quantitatively with existing laboratory evolution experiments and
suggest future experimental directions.


title:
Elliptic integral evaluation of a Bessel moment by contour integration
  of a lattice Green function

abstract:
  A proof is found for the elliptic integral evaluation of the Bessel moment
$$M:=\int_0^\infty t I_0^2(t)K_0^2(t)K_0(2t) {\rm d}t ={1/12} {\bf
K}(\sin(\pi/12)){\bf K}(\cos(\pi/12))
=\frac{\Gamma^6(\frac13)}{64\pi^22^{2/3}}$$ resulting from an angular average
of a 2-loop 4-point massive Feynman diagram, with one internal mass doubled.
This evaluation follows from contour integration of the Green function for a
hexagonal lattice, thereby relating $M$ to a linear combination of two more
tractable moments, one given by the Green function for a diamond lattice and
both evaluated by using W.N. Bailey's reduction of an Appell double series to a
product of elliptic integrals. Cubic and sesquiplicate modular transformations
of an elliptic integral from the equal-mass Dalitz plot are proven and used
extensively. Derivations are given of the sum rules $$\int_0^\infty(I_0(a
t)K_0(a t)-\frac{2}{\pi} K_0(4a t) K_0(t))K_0(t) {\rm d}t=0$$ with $a>0$,
proven by analytic continuation of an identity from Bailey's work, and
$$\int_0^\infty t I_0(a t)(I_0^3(a t)K_0(8t)- \frac{1}{4\pi^2} I_0(t)K_0^3(t))
{\rm d}t=0$$ with $2\ge a\ge0$, proven by showing that a Feynman diagram in two
spacetime dimensions generates the enumeration of staircase polygons in four
dimensions.


title:
Infrared Tracers of Mass-Loss Histories and Wind-ISM Interactions in Hot
  Star Nebulae

abstract:
  Infrared observations of hot massive stars and their environments provide a
detailed picture of mass loss histories, dust formation, and dynamical
interactions with the local stellar medium that can be unique to the thermal
regime. We have acquired new infrared spectroscopy and imaging with the
sensitive instruments onboard the Spitzer Space Telescope in guaranteed and
open time programs comprised of some of the best known examples of hot stars
with circumstellar nebulae, supplementing with unpublished Infrared Space
Observatory spectroscopy. Here we present highlights of our work on the
environment around the extreme P Cygni-type star HDE316285, revealing
collisionally excited H2 for the first time in a hot star nebula, and providing
some defining characteristics of the star's evolution and interactions with the
ISM at unprecented detail in the infrared.


title: Commensurators of cusped hyperbolic manifolds

abstract:
  This paper describes a general algorithm for finding the commensurator of a
non-arithmetic cusped hyperbolic manifold, and for deciding when two such
manifolds are commensurable. The method is based on some elementary
observations regarding horosphere packings and canonical cell decompositions.
For example, we use this to find the commensurators of all non-arithmetic
hyperbolic once-punctured torus bundles over the circle.
  For hyperbolic 3-manifolds, the algorithm has been implemented using
Goodman's computer program Snap. We use this to determine the commensurability
classes of all cusped hyperbolic 3-manifolds triangulated using at most 7 ideal
tetrahedra, and for the complements of hyperbolic knots and links with up to 12
crossings.


title: The Criteria for Interfacial Electro-Thermal Equilibrium

abstract:
  When the surface of a first material is brought into contact with the surface
of a second material the contact region is called an interface. Since the time
of James Clerk Maxwell it has been customary to treat a material electrically
as having well-defined bulk properties and having surfaces of zero-thickness.
In order to obtain a better understanding of the interface this paper reviews
Maxwell's original argument to justify a zero-thickness-surface and reexamines
the interface problem assuming electrical charges are actually particles having
a finite thickness. Thermodynamics requires that in thermal equilibrium any
movement of free charge cannot produce a net electrical current anywhere in the
materials or across their interface. For materials in contact and in thermal
equilibrium this reexamination gives a set of equations that can be called the
interfacial electro-thermal equilibrium (IETE) criteria. A well-defined
interfacial potential results from this criteria.


title: The REESSE2+ Public-key Encryption Scheme

abstract:
  This paper gives the definitions of an anomalous super-increasing sequence
and an anomalous subset sum separately, proves the two properties of an
anomalous super-increasing sequence, and proposes the REESSE2+ public-key
encryption scheme which includes the three algorithms for key generation,
encryption and decryption. The paper discusses the necessity and sufficiency of
the lever function for preventing the Shamir extremum attack, analyzes the
security of REESSE2+ against extracting a private key from a public key through
the exhaustive search, recovering a plaintext from a ciphertext plus a knapsack
of high density through the L3 lattice basis reduction method, and
heuristically obtaining a plaintext through the meet-in-the-middle attack or
the adaptive-chosen-ciphertext attack. The authors evaluate the time complexity
of REESSE2+ encryption and decryption algorithms, compare REESSE2+ with ECC and
NTRU, and find that the encryption speed of REESSE2+ is ten thousand times
faster than ECC and NTRU bearing the equivalent security, and the decryption
speed of REESSE2+ is roughly equivalent to ECC and NTRU respectively.


title:
Random Aharonov-Bohm vortices and some exact families of integrals: Part
  II

abstract:
  At 6th order in perturbation theory, the random magnetic impurity problem at
second order in impurity density narrows down to the evaluation of a single
Feynman diagram with maximal impurity line crossing. This diagram can be
rewritten as a sum of ordinary integrals and nested double integrals of
products of the modified Bessel functions $K_{\nu}$ and $I_{\nu}$, with
$\nu=0,1$. That sum, in turn, is shown to be a linear combination with rational
coefficients of $(2^5-1)\zeta(5)$, $\int_0^{\infty} u K_0(u)^6 du$ and
$\int_0^{\infty} u^3 K_0(u)^6 du$. Unlike what happens at lower orders, these
two integrals are not linear combinations with rational coefficients of Euler
sums, even though they appear in combination with $\zeta(5)$. On the other
hand, any integral $\int_0^{\infty} u^{n+1} K_0(u)^p (uK_1(u))^q du$ with
weight $p+q=6$ and an even $n$ is shown to be a linear combination with
rational coefficients of the above two integrals and 1, a result that can be
easily generalized to any weight $p+q=k$. A matrix recurrence relation in $n$
is built for such integrals. The initial conditions are such that the
asymptotic behavior is determined by the smallest eigenvalue of the transition
matrix.


title:
Orbital Landau level dependence of the fractional quantum Hall effect in
  quasi-two dimensional electron layers: finite-thickness effects

abstract:
  The fractional quantum Hall effect (FQHE) in the second orbital Landau level
at filling factor 5/2 remains enigmatic and motivates our work. We consider the
effect of the quasi-2D nature of the experimental FQH system on a number of FQH
states (fillings 1/3, 1/5, 1/2) in the lowest, second, and third Landau levels
(LLL, SLL, TLL,) by calculating the overlap, as a function of quasi-2D layer
thickness, between the exact ground state of a model Hamiltonian and the
consensus variational wavefunctions (Laughlin wavefunction for 1/3 and 1/5 and
the Moore-Read Pfaffian wavefunction for 1/2). Using large overlap as a
stability, or FQHE robustness, criterion we find the FQHE does not occur in the
TLL (for any thickness), is the most robust for zero thickness in the LLL for
1/3 and 1/5 and for 11/5 in the SLL, and is most robust at finite-thickness
(4-5 magnetic lengths) in the SLL for the mysterious 5/2 state and the 7/3
state. No FQHE is found at 1/2 in the LLL for any thickness. We examine the
orbital effects of an in-plane (parallel) magnetic field finding its
application effectively reduces the thickness and could destroy the FQHE at 5/2
and 7/3, while enhancing it at 11/5 as well as for LLL FQHE states. The
in-plane field effects could thus be qualitatively different in the LLL and the
SLL by virtue of magneto-orbital coupling through the finite thickness effect.
In the torus geometry, we show the appearance of the threefold topological
degeneracy expected for the Pfaffian state which is enhanced by thickness
corroborating our findings from overlap calculations. Our results have
ramifications for wavefunction engineering--the possibility of creating an
optimal experimental system where the 5/2 FQHE state is more likely described
by the Pfaffian state with applications to topological quantum computing.


title:
Cheap Artificial AB-Mountains, Extraction of Water and Energy from
  Atmosphere and Change of Regional Climate

abstract:
  Author suggests and researches a new revolutionary method for changing the
climates of entire countries or portions thereof, obtaining huge amounts of
cheap water and energy from the atmosphere. In this paper is presented the idea
of cheap artificial inflatable mountains, which may cardinally change the
climate of a large region or country. Additional benefits: The potential of
tapping large amounts of fresh water and energy. The mountains are inflatable
semi-cylindrical constructions from thin film (gas bags) having heights of up
to 3 - 5 km. They are located perpendicular to the main wind direction.
Encountering these artificial mountains, humid air (wind) rises to crest
altitude, is cooled and produces rain (or rain clouds). Many natural mountains
are sources of rivers, and other forms of water and power production - and
artificial mountains may provide these services for entire nations in the
future. The film of these gasbags is supported at altitude by small additional
atmospheric overpressure and may be connected to the ground by thin cables. The
author has shown (in previous works about the AB-Dome) that this closed AB-Dome
allows full control of the weather inside the Dome (the day is always fine, the
rain is only at night, no strong winds) and influence to given region. This is
a realistic and cheap method of economical irrigation, getting energy and
virtual weather control on Earth at the current time.


title: $X(1835)$ and $\eta(1760)$ observed by the BES Collaboration

abstract:
  With the assumption that the $X(1835)$ and $\eta(1760)$ recently observed by
the BES Collaboration are the $3\,^1S_0$ meson states, the strong decays of
these two states are investigated in the $^3P_0$ decay model. We find that the
predicted total widths of the $X(1835)$ and $\eta(1760)$ can be reasonably
reproduced with the $X(18350)-\eta(1760)$ mixing angle lying on the range from
$-0.26$ to $+0.55$ radians. Further, the mixing angle of the $X(1835)$ and
$\eta(1760)$ is phenomenologically determined to be about $-0.24$ radians in
the presence of the $\pi(1800)$, $K(1830)$, $\eta(1760)$ and $X(1835)$
belonging to the $3\,^1S_0$ meson nonet. Our estimated mixing angle can
naturally account for the widths of the $X(1835)$ and $\eta(1760)$, which shows
that the assignment of the $X(1835)$ and $\eta(1760)$, together the $\pi(1800)$
and $K(1830)$ as the $3\,^1S_0$ $q\bar{q}$ members seems reasonable.


title: A formula for Pl\"ucker coordinates associated with a planar network

abstract:
  For a planar directed graph G, Postnikov's boundary measurement map sends
positive weight functions on the edges of G onto the appropriate totally
nonnegative Grassmann cell. We establish an explicit formula for Postnikov's
map by expressing each Pluecker coordinate as a ratio of two combinatorially
defined polynomials in the edge weights, with positive integer coefficients. In
the non-planar setting, we show that a similar formula holds for special
choices of Pluecker coordinates.


title:
Coexistence of normal, super-, and hyper-deformation in nuclei: A study
  with angular momentum projection

abstract:
  Angular-momentum-projected energy surface calculations for A~110 nuclei
indicate three distinct energy minima occurring at different angular-momenta.
These correspond to normal, super-, and hyper-deformed shapes coexisting in one
nucleus. 110Pd is studied in detail, with a quantitative prediction on super-
and hyper-deformed spectra by the Projected Shell Model calculation. It is
suggested that several other neighboring nuclei in the A-110 mass region, with
the neutron number around 64, also exhibit clear super- and hyper-deformation
minima.


title:
From Continuous-Time Design to Sampled-Data Design of Nonlinear
  Observers

abstract:
  In this work, a sampled-data nonlinear observer is designed using a
continuous-time design coupled with an inter-sample output predictor. The
proposed sampled-data observer is a hybrid system. It is shown that under
certain conditions, the robustness properties of the continuous-time design are
inherited by the sampled-data design, as long as the sampling period is not too
large. The approach is applied to linear systems and to triangular globally
Lipschitz systems.


title:
Color-Shift Measurement in Microlensing-Induced Stellar Variation from
  Future Space-Based Surveys

abstract:
  If a microlensing event is caused by a star, the event can exhibit change in
color due to the light from the lens. In the previous and current lensing
surveys, the color shift could not be used to constrain the lens population
because the blended light responsible for the color shift is mostly attributed
to nearby background stars rather than the lens. However, events to be observed
in future space-based surveys do not suffer from blending and thus the color
information can be used to constrain lenses. In this paper, we demonstrate the
usefulness of future surveys in measuring color shifts. By conducting
simulation of galactic lensing events based on the specification of a proposed
space-based lensing survey, we estimate that the shift in the color of $R-H$
will be measured at 5$\sigma$ level for $\sim 12%$ of events that occur on
source stars with apparent magnitudes brighter than $J=22.5$. Color-shifted
events tend to have high magnifications and the lenses will have brightnesses
equivalent to those of source stars. The time scales of the color-shifted
events tend to be longer than those without color shifts. From the mass
distribution of lenses, we find that most of the color-shifted events will be
produced by stellar lenses with spectral types down to mid M-type main sequence
stars.


title: The effect of primordial non-Gaussianity on halo bias

abstract:
  It has long been known how to analytically relate the clustering properties
of the collapsed structures (halos) to those of the underlying dark matter
distribution for Gaussian initial conditions. Here we apply the same approach
to physically motivated non-Gaussian models. The techniques we use were
developed in the 1980s to deal with the clustering of peaks of non-Gaussian
density fields. The description of the clustering of halos for non-Gaussian
initial conditions has recently received renewed interest, motivated by the
forthcoming large galaxy and cluster surveys. For inflationary-motivated
non-Gaussianites, we find an analytic expression for the halo bias as a
function of scale, mass and redshift, employing only the approximations of
high-peaks and large separations.


title:
The Subaru/XMM-Newton Deep Survey (SXDS) -VII. Clustering Segregation
  with Ultraviolet and Optical Luminosities of Lyman-Break Galaxies at z~3

abstract:
  We investigate clustering properties of Lyman-break galaxies (LBGs) at z~3
based on deep multi-waveband imaging data from optical to near-infrared
wavelengths in the Subaru/XMM-Newton Deep Field. The LBGs are selected by U-V
and V-z' colors in one contiguous area of 561 arcmin^2 down to z'=25.5. We
study the dependence of the clustering strength on rest-frame UV and optical
magnitudes, which can be indicators of star formation rate and stellar mass,
respectively. The correlation length is found to be a strong function of both
UV and optical magnitudes with brighter galaxies being more clustered than
faint ones in both cases. Furthermore, the correlation length is dependent on a
combination of UV and optical magnitudes in the sense that galaxies bright in
optical magnitude have large correlation lengths irrespective of UV magnitude,
while galaxies faint in optical magnitude have correlation lengths decreasing
with decreasing UV brightness. These results suggest that galaxies with large
stellar masses always belong to massive halos in which they can have various
star formation rates, while galaxies with small stellar masses reside in less
massive halos only if they have low star formation rates. There appears to be
an upper limit to the stellar mass and the star formation rate which is
determined by the mass of hosting dark halos.


title: Microlensing Search for Planets with Two Simultaneously Rising Suns

abstract:
  Among more than 200 extrasolar planet candidates discovered to date, there is
no known planet orbiting around normal binary stars. In this paper, we
demonstrate that microlensing is a technique that can detect such planets.
Microlensing discoveries of these planets are possible because the planet and
host binary stars produce perturbations at a common region around center of
mass of the binary stars and thus the signatures of both planet and binary can
be detected in the light curves of high-magnification microlensing events. The
ranges of the planetary and binary separations of systems for optimal detection
vary depending on the planet mass. For a Jupiter-mass planet, we find that high
detection efficiency is expected for planets located in the range of $\sim$ 1
AU -- 5 AU from the binary stars which are separated by $\sim$ 0.15 AU -- 0.5
AU


title: The final phase of inspiral of strange quark star binaries

abstract:
  We present calculations of the final phase of inspiral of irrotational
strange star binaries. Two types of equation of state at zero temperature are
used - the MIT bag model and the Dey et al. 1998 model of strange quark matter.
We study the precoalescence stage within the Isenberg-Wilson-Mathews
approximation of General Relativity using a multidomain spectral method. The
gravitational-radiation driven evolution of the binary system is approximated
by a sequence of quasi-equilibrium configurations at a fixed baryon number and
with decreasing separation. We find that the innermost stable circular orbit
(ISCO) is determined always by an orbital instability for binaries consisting
of two stars built predominantly of strange quark matter independently on the
total mass of a binary system and compactness parameter of each star. In
contrast, for neutron stars described by baryonic equation of state without
exotic phases the ISCO is given by the mass-shedding limit. The gravitational
wave frequency at the ISCO, which marks the end of the inspiral phase, is
always higher than 1.1kHz for equal masses irrotational strange quark stars
with the total mass-energy of a binary system greater than $2 M_\odot$. We find
that the dependence of the frequency of gravitational waves at the ISCO on the
compactness parameter for the equal mass binaries can be described by the same
simple analytical formulae for broad ranges of masses independently on a
strange star model. Detailed comparisons with binary neutrons star models, as
well as with the third order Post-Newtonian point-mass binaries are given. The
difference in the phase, for two $1.35 M_\odot$ strange stars, between our
numerical results and 3PN is $\sim 40 %$ for the last two orbits of inspiral.


title: Evidence of a boundary layer instability at very high Rayleigh number

abstract:
  In 1997, a Rayleigh-B\'enard experiment evidenced a significant increase of
the heat transport efficiency for Rayleigh numbers larger than $Ra \sim
10^{12}$ and interpreted this observation as the signature of the Kraichnan's
``Ultime Regime'' of convection. According to Kraichnan's 1962 prediction, the
flow boundary layers above the cold and hot plates -in which most of the fluid
temperature drop is localized- become unstable for large enough $Ra$ and this
instability boosts the heat transport compared to the other turbulent regimes.
Using the same convection cell as in the 1997 experiment, we show that the
reported heat transport increase is accompanied with enhanced temperature
fluctuations of the bottom plate, which was heated at constant power levels.
Indeed, for $Ra < 10^{12}$, the bottom plate fluctuations can simply be
accounted from those in the bulk of the flow. In particular, they share the
same spectral density at low frequencies, as if the bottom plate was following
the slow temperature fluctuations of the bulk, modulo a constant temperature
drop across the bottom boundary layer. Conversely, to account for the plate's
temperature fluctuations at higher $Ra$, we no-longuer can ignore the
fluctuations of the temperature drop across the boundary layer. The negative
skewness of fluctuations at high $Ra$ supports the picture of a boundary layer
instability. These observations provide new evidence that the transition
reported in 1997 corresponds to the triggering of the Ultimate Regime of
convection.


title: The signature of subsurface Kondo impurities in the local tunnel current

abstract:
  The conductance of a tunnel point-contact in an STM-like geometry having a
single defect placed below the surface is investigated theoretically. The
effect of multiple electron scattering by the defect after reflections by the
metal surface is taken into account. In the approximation of s-wave scattering
the dependence of the conductance on the applied voltage and the position of
the defect is obtained. The results are illustrated for a model s-wave phase
shift describing Kondo-resonance scattering. We demonstrate that multiple
electron scattering by the magnetic impurity plays a decisive role in the
point-contact conductance at voltages near the Kondo resonance. We find that
the sign and shape of the Kondo anomaly depends on the position of the defect.


title: A representation formula for indefinite improper affine spheres

abstract:
  We construct a new representation formula for indefinite improper affine
spheres in terms of two para-holomorphic functions and study singularities
which appear in this representation formula. As a result, it follows that
cuspidal cross caps never appear as the singularities on indefinite improper
affine spheres and so on. Comparison with other representation formulae are
also studied.


title:
A BQP-complete problem related to the Ising model partition function via
  a new connection between quantum circuits and graphs

abstract:
  We present a simple construction that maps quantum circuits to graphs and
vice-versa. Inspired by the results of D.A. Lidar linking the Ising partition
function with quadratically signed weight enumerators (QWGTs), we also present
a BQP-complete problem for the additive approximation of a function over
hypergraphs related to the generating function of Eulerian subgraphs for
ordinary graphs. We discuss connections with the Ising partition function.


title: Level crossing of particle-hole and mesonic modes in eta mesic nuclei

abstract:
  We study eta meson properties in the infinite nuclear matter and in atomic
nuclei with an emphasis on effects of the eta coupling to
N*(1535)--nucleon-hole modes. The N*(1535) resonance, which dominates the
low-energy eta-nucleon scattering, can be seen as a chiral partner of the
nucleon. The change of the chiral mass gap between the N* and the nucleon in a
nuclear medium has an impact on the properties of the eta-nucleus system. If
the N*-nucleon mass gap decreases with a density increase (chiral symmetry
restoration) the calculations show the existence of the resonance state at the
energy about 60 MeV and two bound eta-nucleus states with the binding energies
about -80 MeV. These states can have strong effect on predicted cross sections
of the ^12C (gamma,p) ^11B reaction with eta-meson production.


title: Tropical and Ordinary Convexity Combined

abstract:
  A polytrope is a tropical polytope which at the same time is convex in the
ordinary sense. A $d$-dimensional polytrope turns out to be a tropical simplex,
that is, it is the tropical convex hull of $d+1$ points. This statement is
equivalent to the known fact that the Segre product of two full polynomial
rings (over some field $K$) has the Gorenstein property if and only if the
factors are generated by the same number of indeterminates. The combinatorial
types of polytropes up to dimension three are classified.


title:
Low temperature electron-phonon resonance in dc-current-biased
  two-dimensional electron systems

abstract:
  Effects of resonant acoustic phonon scattering on magnetoresistivity are
examined in two-dimensional electron systems at low temperatures by using a
balance-equation magnetotransport scheme direct controlled by the current. The
experimentally observed resonances in linear resistivity are shown to result
from the conventional bulk phonon modes in a GaAs-based system, without
invoking leaky interface phonons. Due to quick heating of electrons, phonon
resonances can be dramatically enhanced by a finite bias current. When the
electron drift velocity increases to the speed of sound, additional and
prominent phonon resonance peaks begin to emerge. As a result, remarkable
resistance oscillation and negative differential resistivity can appear in
nonlinear transport in a modest mobility sample at low temperatures, which is
in agreement with recent experiments.


title: Sparse permutation invariant covariance estimation

abstract:
  The paper proposes a method for constructing a sparse estimator for the
inverse covariance (concentration) matrix in high-dimensional settings. The
estimator uses a penalized normal likelihood approach and forces sparsity by
using a lasso-type penalty. We establish a rate of convergence in the Frobenius
norm as both data dimension $p$ and sample size $n$ are allowed to grow, and
show that the rate depends explicitly on how sparse the true concentration
matrix is. We also show that a correlation-based version of the method exhibits
better rates in the operator norm. We also derive a fast iterative algorithm
for computing the estimator, which relies on the popular Cholesky decomposition
of the inverse but produces a permutation-invariant estimator. The method is
compared to other estimators on simulated data and on a real data example of
tumor tissue classification using gene expression data.


title: Active Brownian Motion Models and Applications to Ratchets

abstract:
  We give an overview over recent studies on the model of Active Brownian
Motion (ABM) coupled to reservoirs providing free energy which may be converted
into kinetic energy of motion. First, we present an introduction to a general
concept of active Brownian particles which are capable to take up energy from
the source and transform part of it in order to perform various activities. In
the second part of our presentation we consider applications of ABM to ratchet
systems with different forms of differentiable potentials. Both analytical and
numerical evaluations are discussed for three cases of sinusoidal,
staircase-like and Mateos ratchet potentials, also with the additional loads
modeled by tilted potential structure. In addition, stochastic character of the
kinetics is investigated by considering perturbation by Gaussian white noise
which is shown to be responsible for driving the directionality of the
asymptotic flux in the ratchet. This \textit{stochastically driven
directionality} effect is visualized as a strong nonmonotonic dependence of the
statistics of the right versus left trajectories of motion leading to a net
current of particles. Possible applications of the ratchet systems to molecular
motors are also briefly discussed


title:
Accumulation and extraction of ultracold neutrons from a superfluid
  helium converter coated with fluorinated grease

abstract:
  We report experiments on the production of ultracold neutrons (UCN) in a
converter of superfluid helium coated with fluorinated grease. We employed our
technique of window-free extraction of accumulated UCN from the helium, in
which they were produced by downscattering neutrons of a cold beam from the
Munich research reactor. The time constant for UCN passage through the same
extraction aperture as in a previous experiment was a factor two shorter,
despite a lower mean velocity of the accumulated UCN in the present
experiments. A time-of-flight measurement of the cold neutron spectrum incident
on the converter allowed us to estimate the multi-phonon contribution to the
UCN production. The UCN production rate inferred from two methods agrees with
the theoretical expectation.


title:
Formation of ultra-compact dwarf galaxies: tests of the galaxy threshing
  scenario in Fornax

abstract:
  This paper investigates the possibility that UCD galaxies in the Fornax
cluster are formed by the threshing of nucleated, early-type dwarf galaxies
(hereafter dwarf galaxies).
  Similar to the results of Cote et al. (2006) for the Virgo cluster, we show
that the Fornax Cluster observations are consistent with a single population in
which all dwarfs are nucleated, with a ratio of nuclear to total magnitude that
varies slowly with magnitude. Importantly, the magnitude distribution of the
UCD population is similar to that of the dwarf nuclei in the Fornax cluster.
  The joint population of UCDs and the dwarfs from which they may originate is
modelled and shown to be consistent with an NFW profile with a characteristic
radius of 5 kpc. Furthermore, a steady-state dynamical model reproduces the
known mass profile of Fornax. However, there are a number of peculiarities in
the velocity dispersion data that remain unexplained.
  The simplest possible threshing model is tested, in which dwarf galaxies move
on orbits in a static cluster potential and are threshed if they pass within a
radius at which the tidal force from the cluster exceeds the internal gravity
at the core of their dark matter halo. This fails to reproduce the observed
fraction of UCDs at radii greater than 30 kpc from the core of Fornax.


title: The Darrieus-Landau instability in fast deflagration and laser ablation

abstract:
  The problem of the Darrieus-Landau instability at a discontinuous
deflagration front in a compressible flow is solved. Numerous previous attempts
to solve this problem suffered from the deficit of boundary conditions. Here,
the required additional boundary condition is derived rigorously taking into
account the internal structure of the front. The derived condition implies a
constant mass flux at the front; it reduces to the classical Darrieus-Landau
condition in the limit of an incompressible flow. It is demonstrated that in
general the solution to the problem depends on the type of energy source
present in the system. In the common case of a strongly localized source,
compression effects make the Darrieus-Landau instability considerably weaker.
In particular, the Darrieus-Landau instability growth rate is reduced for laser
ablation in comparison with the classical incompressible case. The instability
disappears completely in the Chapman-Jouguet regime of ultimately fast
deflagration.


title:
Higgs Scalar-Tensor Theory for Gravity and the Flat Rotation Curves of
  Spiral Galaxies

abstract:
  The scalar-tensor theory of gravity with the Higgs field as scalar field is
presented. For central symmetry it reproduces the empirically measured flat
rotation curves of galaxies. We approximate the galaxy by a polytropic gas
sphere with the polytropic index $\gamma=2$ and a massive core.


title:
Can F(R)-gravity be a viable model: the universal unification scenario
  for inflation, dark energy and dark matter

abstract:
  We review on the viability of $F(R)$-gravity. We show that recent cosmic
acceleration, radiation/matter-dominated epoch and inflation could be realized
in the framework of $F(R)$-gravity in the unified way. For some classes of
$F(R)$-gravity, the correction to the Newton law is extremely small and there
is no so-called matter instability (the very heavy positive mass for additional
scalar degree of freedom is generated). The reconstruction program in modified
gravity is also reviewed and it is demonstrated that {\it any} time-evolution
of the universe expansion could be realized in $F(R)$-gravity. Special
attention is paid to modified gravity which unifies inflation with cosmic
acceleration and passes local tests. It turns out that such a theory may
describe also dark matter.


title: Counting growth types of automorphisms of free groups

abstract:
  Given an automorphism of a free group $F_n$, we consider the following
invariants: $e$ is the number of exponential strata (an upper bound for the
number of different exponential growth rates of conjugacy classes); $d$ is the
maximal degree of polynomial growth of conjugacy classes; $R$ is the rank of
the fixed subgroup. We determine precisely which triples $(e,d,R)$ may be
realized by an automorphism of $F_n$. In particular, the inequality $e\le
(3n-2)/4}$ (due to Levitt-Lustig) always holds. In an appendix, we show that
any conjugacy class grows like a polynomial times an exponential under
iteration of the automorphism.


title: Improved lower bound for deterministic broadcasting in radio networks

abstract:
  We consider the problem of deterministic broadcasting in radio networks when
the nodes have limited knowledge about the topology of the network. We show
that for every deterministic broadcasting protocol there exists a network, of
radius 2, for which the protocol takes at least $\Omega(\sqrt{n}) rounds for
completing the broadcast. Our argument can be extended to prove a lower bound
of Omega(\sqrt{nD}) rounds for broadcasting in radio networks of radius D. This
resolves one of the open problems posed in [29], where in the authors proved a
lower bound of $\Omega(n^{1/4}) rounds for broadcasting in constant diameter
networks.
  We prove the new lower $\Omega(\sqrt{n})$ bound for a special family of
radius 2 networks. Each network of this family consists of O(\sqrt{n})
components which are connected to each other via only the source node. At the
heart of the proof is a novel simulation argument, which essentially says that
any arbitrarily complicated strategy of the source node can be simulated by the
nodes of the networks, if the source node just transmits partial topological
knowledge about some component instead of arbitrary complicated messages. To
the best of our knowledge this type of simulation argument is novel and may be
useful in further improving the lower bound or may find use in other
applications.
  Keywords: radio networks, deterministic broadcast, lower bound, advice
string, simulation, selective families, limited topological knowledge.


title: Virial Equation-of-State for Hard Spheres

abstract:
  Recent values for virial coefficients up to B12, when expressed in powers of
density relative to maximum close packing,lead to a closed equation-of-state
for the equilibrium fluid. The series obtained converges for all densities;it
becomes negative and diverges to a negative pole at maximum packing. MD data
for 64000 spheres in the metastable region shows the virial pressure begins to
deviate at the fluid freezing density.


title: Cohomology rings and formality properties of nilpotent groups

abstract:
  We introduce partial formality and relate resonance with partial formality
properties. For instance, we show that for finitely generated nilpotent groups
that are k-formal, the resonance varieties are trivial up to degree k. We also
show that the cohomology ring of a nilpotent k-formal group is generated in
degree 1, up to degree k+1; this criterion is necessary and sufficient for
2-step nilpotent groups to be k-formal. We compute resonance varieties for
Heisenberg-type groups and deduce the degree of partial formality for this
class of groups.


title: Noise Effects in Quantum Magic Squares Game

abstract:
  In the article we analyse how noisiness of quantum channels can influence the
magic squares quantum pseudo-telepathy game. We show that the probability of
success can be used to determine characteristics of quantum channels. Therefore
the game deserves more careful study aiming at its implementation.


title:
Zero-field spin-splitting and spin lifetime in n-InSb/In1-xAlxSb
  asymmetric quantum well heterostructures

abstract:
  The spin-orbit (SO) coupling parameters for lowest conduction subband due to
structural (SIA) and bulk (BIA) inversion asymmetry are calculated for a range
of carrier densities in [001]-grown delta-doped n-type InSb/In1-xAlxSb
asymmetric quantum wells using the established 8 band k.p formalism [PRB 59,8
R5312 (1999)]. We present calculations for conditions of zero bias at 10 K. It
is shown that both the SIA and BIA parameters scale approximately linearly with
carrier density, and exhibit a marked dependence on well width when alloy
composition is adjusted to allow maximum upper barrier height for a given well
width. In contrast to other material systems the BIA contribution to spin
splitting is found to be of significant and comparable value to the SIA
mechanism in these structures. We calculate the spin lifetime for spins
oriented along [11-0] based on D'yakonov-Perel mechanism using both the theory
of Averkiev et al. [J. Phys.:Condens. Matter 14 (2002)] and also the rate of
precession of spins about the effective magnetic field, taking into account all
three SO couplings, showing good agreement.Spin lifeime for this direction is
largest in the narrow wells over the range of moderate carrier densities
considered, which is attributed to the reduced magnitude of the k-cubic BIA
parameter in narrow wells. The inherently large BIA induced SO coupling in
these systems is shown to have considerable effect on the spin lifetime, which
exhibits significant reduction in the maximum spin lifetime compared to
previous studies which consider systems with relatively weak BIA induced SO
coupling. The relaxation rate of spins oriented in the [001] direction is
dominated by the k-linear SIA and BIA coupling parameters and at least an order
of magnitude greater than in the [11-0] direction.


title: Coherence and incoherence in extended broad band triplet interaction

abstract:
  In the present analysis we study the transition from coherent to incoherent
dynamics in a nonlinear triplet of broad band combs of waves. Expanding the
analysis of previous works, this paper investigates what happens when the band
of available modes is much larger than that of the initial narrower combs
within which the nonlinear interaction is not subjected to selection rules
involving wave momenta. Here selection rules are present and active, and we
examine how and when coherence can be defined.


title: Bicretieria Optimization in Routing Games

abstract:
  Two important metrics for measuring the quality of routing paths are the
maximum edge congestion $C$ and maximum path length $D$. Here, we study
bicriteria in routing games where each player $i$ selfishly selects a path that
simultaneously minimizes its maximum edge congestion $C_i$ and path length
$D_i$. We study the stability and price of anarchy of two bicriteria games:
  - {\em Max games}, where the social cost is $\max(C,D)$ and the player cost
is $\max(C_i, D_i)$. We prove that max games are stable and convergent under
best-response dynamics, and that the price of anarchy is bounded above by the
maximum path length in the players' strategy sets. We also show that this bound
is tight in worst-case scenarios.
  - {\em Sum games}, where the social cost is $C+D$ and the player cost is
$C_i+D_i$. For sum games, we first show the negative result that there are game
instances that have no Nash-equilibria. Therefore, we examine an approximate
game called the {\em sum-bucket game} that is always convergent (and therefore
stable). We show that the price of anarchy in sum-bucket games is bounded above
by $C^* \cdot D^* / (C^* + D^*)$ (with a poly-log factor), where $C^*$ and
$D^*$ are the optimal coordinated congestion and path length. Thus, the
sum-bucket game has typically superior price of anarchy bounds than the max
game. In fact, when either $C^*$ or $D^*$ is small (e.g. constant) the social
cost of the Nash-equilibria is very close to the coordinated optimal $C^* +
D^*$ (within a poly-log factor). We also show that the price of anarchy bound
is tight for cases where both $C^*$ and $D^*$ are large.


title: Polytropic spheres in Palatini f(R) gravity

abstract:
  We examine static spherically symmetric polytropic spheres in Palatini f(R)
gravity and show that no regular solutions to the field equations exist for
physically relevant cases such as a monatomic isentropic gas or a degenerate
electron gas, thus casting doubt on the validity of Palatini f(R) gravity as an
alternative to General Relativity.


title:
Region of Variability for Spirallike Functions with Respect to a
  Boundary Point

abstract:
  In this paper we determine the region of variability for spirallike funcions
with respect to a boundary point. In the final section we graphically
illustrate the region of variability for several sets of parameters.


title:
The Wheeler - DeWitt Quantum Geometrodynamics: its fundamental problems
  and tendencies of their resolution

abstract:
  The paper is devoted to fundamental problems of the Wheeler - DeWitt quantum
geometrodynamics, which was the first attempt to apply quantum principles to
the Universe as a whole. Our purpose is to find out the origin of these
problems and follow up their consequences. We start from Dirac generalized
Hamiltonian dynamics as a cornerstone on which the Wheeler - DeWitt theory is
based. We remind the main statements of the famous DeWitt's paper of 1967 and
discuss the flaws of the theory: the well-known problem of time, the problem of
Hilbert space and others. In the concluding part of the paper we consider new
tendencies and approaches to quantum geometrodynamics appeared in the last
decade.


title:
Diluted one-dimensional spin glasses with power law decaying
  interactions

abstract:
  We introduce a diluted version of the one dimensional spin-glass model with
interactions decaying in probability as an inverse power of the distance. In
this model varying the power corresponds to change the dimension in short-range
models. The spin-glass phase is studied in and out of the range of validity of
the mean-field approximation in order to discriminate between different
theories. Since each variable interacts only with a finite number of others the
cost for simulating the model is drastically reduced with respect to the fully
connected version and larger sizes can be studied. We find both static and
dynamic evidence in favor of the so-called replica symmetry breaking theory.


title: Quantum Hall physics in rotating Bose-Einstein condensates

abstract:
  The close theoretical analogy between the physics of rapidly rotating atomic
Bose condensates and the quantum Hall effect (i.e., a two dimensional electron
gas in a strong magnetic field) was first pointed out ten years ago. As a
consequence of this analogy, a large number of strongly correlated quantum
Hall-type states have been predicted to occur in rotating Bose systems, and
suggestions have been made how to manipulate and observe their fractional
quasiparticle excitations. Due to a very rapid development in experimental
techniques over the past years, experiments on BEC now appear to be close to
reaching the quantum Hall regime. This paper reviews the theoretical and
experimental work done to date in exploring quantum Hall physics in cold
bosonic gases. Future perspectives are discussed briefly, in particular the
idea of exploiting some of these strongly correlated states in the context of
topological quantum computing.