title: Re II and Other Exotic Spectra in HD 65949

abstract:
  Powerful astronomical spectra reveal an urgent need for additional work on
atomic lines, levels, and oscillator strengths. The star HD 65949 provides some
excellent examples of species rarely identified in stellar spectra. For
example, the Re II spectrum is well developed, with 17 lines between 3731 and
4904 [A], attributed wholly or partially to Re II. Classifications and
oscillator strengths are lacking for a number of these lines. The spectrum of
Os II is well identified. Of 14 lines attributed wholly or partially to Os II,
only one has an entry in the VALD database. We find strong evidence that Te II
is present. There are NO Te II lines in the VALD database. Ru II is clearly
present, but oscillator strengths for lines in the visual are lacking. There is
excellent to marginal evidence for a number of less commonly identified
species, including Kr II, Nb II, Sb II, Xe II, Pr III, Ho III, Au II, and Pt II
(probably Pt-198), to be present in the spectrum of HD 65949. The line Hg II at
3984 [A] is of outstanding strength, and all three lines of Multiplet 1 of Hg I
are present, even though the surface temperature of HD 65949 is relatively
high. Finally, we present the case of an unidentified, 24 [mA], line at 3859.63
[A], which could be the same feature seen in magnetic CP stars. It is typically
blended with a putative U II line used in cosmochronology.


title:
Correlation-induced metal insulator transition in a two-channel
  fermion-boson model

abstract:
  We investigate charge transport within some background medium by means of an
effective lattice model with a novel form of fermion-boson coupling. The bosons
describe fluctuations of a correlated background. By analyzing groundstate and
spectral properties of this transport model, we show how a metal-insulator
quantum phase transition can occur for the half-filled band case. We discuss
the evolution of a mass-asymmetric band structure in the insulating phase and
establish connections to the Mott and Peierls transition scenarios.


title:
Genericity of blackhole formation in the gravitational collapse of
  homogeneous self-interacting scalar fields

abstract:
  The gravitational collapse of a wide class of self-interacting homogeneous
scalar fields models is analyzed. The class is characterized by certain general
conditions on the scalar field potential, which, in particular, include both
asymptotically polynomial and exponential behaviors. Within this class, we show
that the generic evolution is always divergent in a finite time, and then make
use of this result to construct radiating star models of the Vaidya type. It
turns out that blackholes are generically formed in such models.


title:
Image Deconvolution Under Poisson Noise Using Sparse Representations and
  Proximal Thresholding Iteration

abstract:
  We propose an image deconvolution algorithm when the data is contaminated by
Poisson noise. The image to restore is assumed to be sparsely represented in a
dictionary of waveforms such as the wavelet or curvelet transform. Our key
innovations are: First, we handle the Poisson noise properly by using the
Anscombe variance stabilizing transform leading to a non-linear degradation
equation with additive Gaussian noise. Second, the deconvolution problem is
formulated as the minimization of a convex functional with a data-fidelity term
reflecting the noise properties, and a non-smooth sparsity-promoting penalties
over the image representation coefficients (e.g. l1-norm). Third, a fast
iterative backward-forward splitting algorithm is proposed to solve the
minimization problem. We derive existence and uniqueness conditions of the
solution, and establish convergence of the iterative algorithm. Experimental
results are carried out to show the striking benefits gained from taking into
account the Poisson statistics of the noise. These results also suggest that
using sparse-domain regularization may be tractable in many deconvolution
applications, e.g. astronomy or microscopy.


title: Explicit a priori bounds on transfer operator eigenvalues

abstract:
  We provide explicit bounds on the eigenvalues of transfer operators defined
in terms of holomorphic data.


title:
Topological 4-manifolds with geometrically 2-dimensional fundamental
  groups

abstract:
  Closed oriented 4-manifolds with the same geometrically 2-dimensional
fundamental group (satisfying certain properties) are classified up to
$s$-cobordism by their $w_2$-type, equivariant intersection form and the
Kirby-Siebenmann invariant. As an application, we obtain a complete
homeomorphism classification of closed oriented 4-manifolds with solvable
Baumslag-Solitar fundamental groups, including a precise realization result.


title: Quasi-coherent sheaves on the moduli stack of formal groups

abstract:
  The central aim of this monograph is to provide decomposition results for
quasi-coherent sheaves on the moduli stack of one-dimensional formal groups.
These results will be based on the geometry of the stack itself, particularly
the height filtration and an analysis of the formal neighborhoods of the
geometric points. The main theorems are algebraic chromatic convergence results
and fracture square decompositions. There is a major technical hurdle in this
story, as the moduli stack of formal groups does not have the finitness
properties required of an algebraic stack as usually defined. This is not a
conceptual problem, but in order to be clear on this point and to write down a
self-contained narrative, I have included a great deal of discussion of the
geometry of the stack itself, giving various equivalent descriptions.


title: Failure of microcausality in noncommutative field theories

abstract:
  We revisit the question of microcausality violations in quantum field theory
on noncommutative spacetime, taking $O(x)=:\phi\star\phi:(x)$ as a sample
observable. Using methods of the theory of distributions, we precisely describe
the support properties of the commutator [O(x),O(y)] and prove that, in the
case of space-space noncommutativity, it does not vanish at spacelike
separation in the noncommuting directions. However, the matrix elements of this
commutator exhibit a rapid falloff along an arbitrary spacelike direction
irrespective of the type of noncommutativity. We also consider the star
commutator for this observable and show that it fails to vanish even at
spacelike separation in the commuting directions and completely violates
causality. We conclude with a brief discussion about the modified Wightman
functions which are vacuum expectation values of the star products of fields at
different spacetime points.


title:
LkH$\alpha$ 330: Evidence for dust clearing through resolved
  submillimeter imaging

abstract:
  Mid-infrared spectrophotometric observations have revealed a small sub-class
of circumstellar disks with spectral energy distributions (SEDs) suggestive of
large inner gaps with low dust content. However, such data provide only an
indirect and model dependent method of finding central holes. We present here
the direct characterization of a 40 AU radius inner gap in the disk around LkHa
330 through 340 GHz (880 micron) dust continuum imaging with the Submillimeter
Array (SMA). This large gap is fully resolved by the SMA observations and
mostly empty of dust with less than 1.3 x 10^-6 M_solar of solid particles
inside of 40 AU. Gas (as traced by accretion markers and CO M-band emission) is
still present in the inner disk and the outer edge of the gap rises steeply --
features in better agreement with the underlying cause being gravitational
perturbation than a more gradual process such as grain growth. Importantly, the
good agreement of the spatially resolved data and spectrophometry-based model
lends confidence to current interpretations of SEDs with significant dust
emission deficits as arising from disks with inner gaps or holes. Further
SED-based searches can therefore be expected to yield numerous additional
candidates that can be examined at high spatial resolution.


title: Mirror Symmetry, Hitchin's Equations, And Langlands Duality

abstract:
  Geometric Langlands duality can be understood from statements of mirror
symmetry that can be formulated in purely topological terms for an oriented
two-manifold $C$. But understanding these statements is extremely difficult
without picking a complex structure on $C$ and using Hitchin's equations. We
sketch the essential statements both for the ``unramified'' case that $C$ is a
compact oriented two-manifold without boundary, and the ``ramified'' case that
one allows punctures. We also give a few indications of why a more precise
description requires a starting point in four-dimensional gauge theory.


title: Discovery potential for Higgs bosons beyond the SM

abstract:
  The discovery potential of the CMS detector for the MSSM neutral and charged
Higgs bosons at the LHC is presented based on studies with full detector
simulation and event reconstruction of the principal discovery channels.


title:
A note on the violation of the Einstein relation in a driven moderately
  dense granular gas

abstract:
  The Einstein relation for a driven moderately dense granular gas in
$d$-dimensions is analyzed in the context of the Enskog kinetic equation. The
Enskog equation neglects velocity correlations but retains spatial correlations
arising from volume exclusion effects. As expected, there is a breakdown of the
Einstein relation $\epsilon=D/(T_0\mu)\neq 1$ relating diffusion $D$ and
mobility $\mu$, $T_0$ being the temperature of the impurity. The kinetic theory
results also show that the violation of the Einstein relation is only due to
the strong non-Maxwellian behavior of the reference state of the impurity
particles. The deviation of $\epsilon$ from unity becomes more significant as
the solid volume fraction and the inelasticity increase, especially when the
system is driven by the action of a Gaussian thermostat. This conclusion
qualitatively agrees with some recent simulations of dense gases [Puglisi {\em
et al.}, 2007 {\em J. Stat. Mech.} P08016], although the deviations observed in
computer simulations are more important than those obtained here from the
Enskog kinetic theory. Possible reasons for the quantitative discrepancies
between theory and simulations are discussed.


title: New Estimation Procedures for PLS Path Modelling

abstract:
  Given R groups of numerical variables X1, ... XR, we assume that each group
is the result of one underlying latent variable, and that all latent variables
are bound together through a linear equation system. Moreover, we assume that
some explanatory latent variables may interact pairwise in one or more
equations. We basically consider PLS Path Modelling's algorithm to estimate
both latent variables and the model's coefficients. New "external" estimation
schemes are proposed that draw latent variables towards strong group structures
in a more flexible way. New "internal" estimation schemes are proposed to
enable PLSPM to make good use of variable group complementarity and to deal
with interactions. Application examples are given.


title:
Spin-transfer switching and low-field precession in exchange-biased spin
  valve nano-pillars

abstract:
  Using a three-dimensional focused-ion beam lithography process we have
fabricated nanopillar devices which show spin transfer torque switching at zero
external magnetic fields. Under a small in-plane external bias field, a
field-dependent peak in the differential resistance versus current is observed
similar to that reported in asymmetrical nanopillar devices. This is
interpreted as evidence for the low-field excitation of spin waves which in our
case is attributed to a spin-scattering asymmetry enhanced by the IrMn exchange
bias layer coupled to a relatively thin CoFe fixed layer.


title:
Runaway and hypervelocity stars in the Galactic halo: Binary
  rejuvenation and triple disruption

abstract:
  Young stars observed in the distant Galactic halo are usually thought to have
formed elsewhere, either in the Galactic disk or perhaps the Galactic center,
and subsequently ejected at high velocities to their current position. However,
some of these stars have apparent lifetimes shorter the required flight time
from the Galactic disk/center. We suggest that such stars have evolved in close
runaway or hypervelocity binaries. Stellar evolution of such binaries can drive
them into mass transfer configurations and even mergers. Such evolution could
then rejuvenate them (e.g. blue stragglers) and extend their lifetime after
their ejection. The extended lifetimes of such stars could then be reconciled
with their flight times to the Galactic halo. We study the possibilities of
binary runaway and hypervelocity stars and show that such binaries could have
been ejected in triple disruptions and other dynamical interactions with stars
or with massive black holes. We show that currently observed "too young" star
in the halo could have been ejected from the Galactic disk or the Galactic
center and be observable in their current position if they were ejected as
binaries. Specifically it is shown that the hypervelocity star HE 0437-5439
could be such a rejuvenated star. Other suggestions for its ejection from the
LMC are found to be highly unlikely. Moreover, it is shown that its observed
metallicity is most consistent with a Galactic origin and a Galactic center
origin can not currently rule out. In addition, we suggest that triple
disruptions by the massive black hole in the Galactic center could also capture
binaries in close orbits near the MBH, some of which may later evolve to become
more massive rejuvenated stars.


title:
Quotient groups of the fundamental groups of certain strata of the
  moduli space of quadratic differentials

abstract:
  In this paper, we study fundamental groups of strata of the moduli space of
quadratic differentials. We use certain properties of the Abel-Jacobi map,
combined with local surgeries on quadratic differentials, to construct quotient
groups of the fundamental groups for a particular family of strata.


title: The Adams-Novikov Spectral Sequence and the Homotopy Groups of Spheres

abstract:
  These are notes for a five lecture series intended to uncover large-scale
phenomena in the homotopy groups of spheres using the Adams-Novikov Spectral
Sequence. The lectures were given in Strasbourg, May 7-11, 2007.


title:
Voltage and Temperature Dependence of High-Field Magnetoresistance in
  Arrays of Magnetic Nanoparticles

abstract:
  Huge values of high field magnetoresistance have been recently reported in
large arrays of CoFe nanoparticles embedded in an organic insulating lattice in
the Coulomb blockade regime. An unusual exponential decrease of
magnetoresistance with increasing voltage was observed, as well as a
characteristic scaling of the magnetoresistance amplitude versus the
field-temperature ratio. We propose a model which takes into account the
influence of paramagnetic impurities on the transport properties of the system
to describe these features. It is assumed that the non-colinearity between the
core spins inside the nanoparticles and the paramagnetic impurities can be
modelled by an effective tunnel barrier, the height of which depends on the
relative angle between the magnetization of both kind of spins. The influence
on the magnetotransport properties of the height and the thickness of the
effective tunnel barrier of the magnetic moment of the impurity, as well as the
bias voltage are studied. This model allows us to reproduce the large
magnetoresistance magnitude observed and its strong voltage dependence, with
realistic parameters.


title: Calculations of Sobol indices for the Gaussian process metamodel

abstract:
  Global sensitivity analysis of complex numerical models can be performed by
calculating variance-based importance measures of the input variables, such as
the Sobol indices. However, these techniques, requiring a large number of model
evaluations, are often unacceptable for time expensive computer codes. A well
known and widely used decision consists in replacing the computer code by a
metamodel, predicting the model responses with a negligible computation time
and rending straightforward the estimation of Sobol indices. In this paper, we
discuss about the Gaussian process model which gives analytical expressions of
Sobol indices. Two approaches are studied to compute the Sobol indices: the
first based on the predictor of the Gaussian process model and the second based
on the global stochastic process model. Comparisons between the two estimates,
made on analytical examples, show the superiority of the second approach in
terms of convergence and robustness. Moreover, the second approach allows to
integrate the modeling error of the Gaussian process model by directly giving
some confidence intervals on the Sobol indices. These techniques are finally
applied to a real case of hydrogeological modeling.


title: Global sensitivity analysis of computer models with functional inputs

abstract:
  Global sensitivity analysis is used to quantify the influence of uncertain
input parameters on the response variability of a numerical model. The common
quantitative methods are applicable to computer codes with scalar input
variables. This paper aims to illustrate different variance-based sensitivity
analysis techniques, based on the so-called Sobol indices, when some input
variables are functional, such as stochastic processes or random spatial
fields. In this work, we focus on large cpu time computer codes which need a
preliminary meta-modeling step before performing the sensitivity analysis. We
propose the use of the joint modeling approach, i.e., modeling simultaneously
the mean and the dispersion of the code outputs using two interlinked
Generalized Linear Models (GLM) or Generalized Additive Models (GAM). The
``mean'' model allows to estimate the sensitivity indices of each scalar input
variables, while the ``dispersion'' model allows to derive the total
sensitivity index of the functional input variables. The proposed approach is
compared to some classical SA methodologies on an analytical function. Lastly,
the proposed methodology is applied to a concrete industrial computer code that
simulates the nuclear fuel irradiation.


title:
Decay dynamics of neutral and charged excitonic complexes in single
  InAs/GaAs quantum dots

abstract:
  Systematic time-resolved measurements on neutral and charged excitonic
complexes (X, XX, X+, and XX+) of 26 different single InAs/GaAs quantum dots
are reported. The ratios of the decay times are discussed in terms of the
number of transition channels determined by the excitonic fine structure and a
specific transition time for each channel. The measured ratio for the neutral
complexes is 1.7 deviating from the theoretically predicted value of 2. A ratio
of 1.5 for the positively charged exciton and biexciton decay time is predicted
and exactly matched by the measured ratio indicating identical specific
transition times for the transition channels involved.


title:
Quantum critical transition from charge-ordered to superconducting state
  in the triangular lattice negative-U extended Hubbard model

abstract:
  We demonstrate a robust frustration-driven charge-order to superconductivity
transition in the half-filled negative-U extended Hubbard model.
Superconductivity extends over a broad region of the parameter space. We argue
that the model provides the correct insight to understanding unconventional
superconductivity in the organic charge-transfer solids and other
quarter-filled systems.


title: The VIMOS VLT Deep Survey: The K-band follow-up in the 0226-04 field

abstract:
  AIMS. We present a new Ks-band survey that represents a significant extension
to the previous wide-field Ks-band imaging survey within the 0226-04 field of
the VIMOS-VLT deep survey (VVDS). The new data add ~ 458 arcmin^2 to the
previous imaging program, thus allowing us to cover a total contiguous area of
~ 600 arcmin^2 within this field. METHODS. Sources are identified both directly
on the final K-band mosaic image and on the corresponding, deep chi^2-g'r'i'
image from the CFHT Legacy Survey in order to reduce contamination while
ensuring us the compilation of a truly K-selected catalogue down to the
completeness limit of the Ks-band. The newly determined Ks-band magnitudes are
used in combination with the ancillary multiwavelength data for the
determination of accurate photometric redshifts. RESULTS. The final catalogue
totals ~ 52000 sources, out of which ~ 4400 have a spectroscopic redshift from
the VVDS first epoch survey. The catalogue is 90% complete down to K_Vega =
20.5 mag. We present K_s-band galaxy counts and angular correlation function
measurements down to such magnitude limit. Our results are in good agreement
with previously published work. We show that the use of K magnitudes in the
determination of photometric redshifts significantly lowers the incidence of
catastrophic errors. The data presented in this paper are publicly available
through the CENCOS database.


title: Vibrational resonances in 1D Morse and FPU lattices

abstract:
  In the present paper the resonances of vibrational modes in one-dimensional
random Morse lattice are found and analyzed. The resonance energy exchange is
observed at some values of elongation. Resonance $2 \omega_1 = \omega_2$ is
investigated in details. The interacting modes are inequivalent: the
higher-frequency mode is much more stable in the excited state, i.e. its
life-time is larger than the life-time of lower-frequency mode under the
resonance conditions. Simple model of two nonlinearly coupled harmonic
oscillators is also considered. It allows to get analytical description and to
investigate the kinetics and the energy exchange degree vs. such parameters as
the resonance detuning and specific energy. The very similar behavior is found
in the Morse and the two-oscillatory models, and an excellent agreement between
analytical and numerical results is obtained. Analogous resonance phenomena are
also found in the random Fermi-Pasta-Ulam lattice under contraction.


title: Volume modulus inflation and a low scale of SUSY breaking

abstract:
  The relation between the Hubble constant and the scale of supersymmetry
breaking is investigated in models of inflation dominated by a string modulus.
Usually in this kind of models the gravitino mass is of the same order of
magnitude as the Hubble constant which is not desirable from the
phenomenological point of view. It is shown that slow-roll saddle point
inflation may be compatible with a low scale of supersymmetry breaking only if
some corrections to the lowest order Kahler potential are taken into account.
However, choosing an appropriate Kahler potential is not enough. There are also
conditions for the superpotential, and e.g. the popular racetrack
superpotential turns out to be not suitable. A model is proposed in which
slow-roll inflation and a light gravitino are compatible. It is based on a
superpotential with a triple gaugino condensation and the Kahler potential with
the leading string corrections. The problem of fine tuning and experimental
constraints are discussed for that model.


title: Small Is Not Always Beautiful

abstract:
  Peer-to-peer content distribution systems have been enjoying great
popularity, and are now gaining momentum as a means of disseminating video
streams over the Internet. In many of these protocols, including the popular
BitTorrent, content is split into mostly fixed-size pieces, allowing a client
to download data from many peers simultaneously. This makes piece size
potentially critical for performance. However, previous research efforts have
largely overlooked this parameter, opting to focus on others instead. This
paper presents the results of real experiments with varying piece sizes on a
controlled BitTorrent testbed. We demonstrate that this parameter is indeed
critical, as it determines the degree of parallelism in the system, and we
investigate optimal piece sizes for distributing small and large content. We
also pinpoint a related design trade-off, and explain how BitTorrent's choice
of dividing pieces into subpieces attempts to address it.


title: On the Decay Rate of the False Vacuum

abstract:
  The finite size theory of metastability in a quartic potential is developed
by the semiclassical path integral method. In the quantum regime, the relation
between temperature and classical particle energy is found in terms of the
first complete elliptic integral. At the sphaleron energy, the criterion which
defines the extension of the quantum regime is recovered. Within the latter,
the temperature effects on the fluctuation spectrum are evaluated by the
functional determinants method and computed. The eigenvalue which causes
metastability is determined as a function of size/temperature by solving a
Lam\`{e} equation. The ground state lifetime shows remarkable deviations with
respect to the result of the infinite size theory.


title: Entanglement Entropy, Trace Anomalies and Holography

abstract:
  The holographic representation of the entanglement entropy of four
dimensional conformal field theories is studied. By generalizing the replica
trick the anomalous terms in the entanglement entropy are evaluated. The same
terms in the holographic representation are calculated by a method which does
not require the solution of the equations of motion or a cut off. The two
calculations disagree for rather generic geometries. The reasons for the
disagreement are analyzed.


title:
High-field and low field magnetoresistance of CoFe nanoparticles
  elaborated by organometallic chemistry

abstract:
  We report on magnetotransport measurements on CoFe nanoparticles surrounded
by an insulating organic layer. Samples were obtained by evaporating a solution
of nanoparticles on a patterned substrate. Typical behaviour of Coulomb
blockade in array of nanoparticles is observed. High and low field
magnetoresistance have been evidenced. Below 10 K, a large high-field
magnetoresistance is measured, reaching up to 500 %. Its amplitude decreases
strongly with increasing voltage. At 1.6 K, this high-field magnetoresistance
vanishes and an inverse low field tunnelling magnetoresistance is observed.


title:
On the distribution of the free path length of the linear flow in a
  honeycomb

abstract:
  Let $\ell \geq 2$ be an integer. For each $\eps >0$ remove from $\R^2$ the
union of discs of radius $\eps$ centered at the integer lattice points $(m,n$,
with $m\nequiv n\mod{\ell}$. Consider a point-like particle moving linearly at
unit speed, with velocity $\omega$, along a trajectory starting at the origin,
and its free path length $\tau_{\ell,\eps} (\omega)\in [0,\infty]$. We prove
the weak convergence of the probability measures associated with the random
variables $\eps \tau_{\ell,\eps}$ as $\eps \to 0^+$ and explicitly compute the
limiting distribution. For $\ell=3$ this leads to an asymptotic formula for the
length of the trajectory of a billiard in a regular hexagon, starting at the
center, with circular pockets of radius $\eps\to 0^+$ removed from the corners.
For $\ell=2$ this corresponds to the trajectory of a billiard in a unit square
with circular pockets removed from the corners and trajectory starting at the
center of the square. The limiting probability measures on $[0,\infty)$ have a
tail at infinity, which contrasts with the case of a square with pockets and
trajectory starting from one of the corners, where the limiting probability
measure has compact support.


title: Constructing Non-Abelian Vortices with Arbitrary Gauge Groups

abstract:
  We construct the general vortex solution in the fully-Higgsed, color-flavor
locked vacuum of a non-Abelian gauge theory, where the gauge group is taken to
be the product of an arbitrary simple group and U(1), with a Fayet-Iliopoulos
term. The vortex moduli space is determined.


title:
Regularity on abelian varieties III: relationship with Generic Vanishing
  and applications

abstract:
  We describe the relationship between the notions of $M$-regular sheaf and
$GV$-sheaf in the case of abelian varieties. The former is a natural
strengthening of the latter, and we provide an algebraic criterion
characterizing it among the larger class. Based on this we deduce new basic
properties of both $M$-regular and $GV$-sheaves. In the second part we give a
number of applications of generation criteria for $M$-regular sheaves to the
study of Seshadri constants, Picard bundles, pluricanonical maps on irregular
varieties, and semihomogeneous vector bundles. This second part of the paper is
based on our earlier preprint math.AG/0306103, with some improved statements
and shortened arguments.


title: The Klein-Gordon equation with the Kratzer potential in d dimensions

abstract:
  We apply the Asymptotic Iteration Method to obtain the bound-state energy
spectrum for the d-dimensional Klein-Gordon equation with scalar S(r) and
vector potentials V(r). When S(r) and V(r) are both Coulombic, we obtain all
the exact solutions; when the potentials are both of Kratzer type, we obtain
all the exact solutions for S(r)=V(r); if S(r) > V(r) we obtain exact solutions
under certain constraints on the potential parameters: in this case, a possible
general solution is found in terms of a monic polynomial, whose coefficients
form a set of elementary symmetric polynomials.


title:
The Simple Non-degenerate Relativistic Gas: Statistical Properties and
  Brownian Motion

abstract:
  This paper shows a novel calculation of the mean square displacement of a
classical Brownian particle in a relativistic thermal bath. The result is
compared with the expressions obtained by other authors. Also, the
thermodynamic properties of a non-degenerate simple relativistic gas are
reviewed in terms of a treatment performed in velocity space.


title: Synchronizing Huygens's clocks

abstract:
  We introduce an interaction mechanism between oscillators leading to exact
anti-phase and in-phase synchronization. This mechanism is applied to the
coupling between two nonlinear oscillators with a limit cycle in phase space,
leading to a simple justification of the anti-phase synchronization observed in
the Huygens's pendulum clocks experiment. If the two coupled nonlinear
oscillators reach the anti-phase or the in-phase synchronized oscillatory
state, the period of oscillation is different from the eigen-periods of the
uncoupled oscillators.


title:
Reduction principles for quantile and Bahadur-Kiefer processes of
  long-range dependent linear sequences

abstract:
  In this paper we consider quantile and Bahadur-Kiefer processes for long
range dependent linear sequences. These processes, unlike in previous studies,
are considered on the whole interval $(0,1)$. As it is well-known, quantile
processes can have very erratic behavior on the tails. We overcome this problem
by considering these processes with appropriate weight functions. In this way
we conclude strong approximations that yield some remarkable phenomena that are
not shared with i.i.d. sequences, including weak convergence of the
Bahadur-Kiefer processes, a different pointwise behavior of the general and
uniform Bahadur-Kiefer processes, and a somewhat "strange" behavior of the
general quantile process.


title:
An Empirical Study of Cache-Oblivious Priority Queues and their
  Application to the Shortest Path Problem

abstract:
  In recent years the Cache-Oblivious model of external memory computation has
provided an attractive theoretical basis for the analysis of algorithms on
massive datasets. Much progress has been made in discovering algorithms that
are asymptotically optimal or near optimal. However, to date there are still
relatively few successful experimental studies. In this paper we compare two
different Cache-Oblivious priority queues based on the Funnel and Bucket Heap
and apply them to the single source shortest path problem on graphs with
positive edge weights. Our results show that when RAM is limited and data is
swapping to external storage, the Cache-Oblivious priority queues achieve
orders of magnitude speedups over standard internal memory techniques. However,
for the single source shortest path problem both on simulated and real world
graph data, these speedups are markedly lower due to the time required to
access the graph adjacency list itself.


title: The effect of nonlinearity on adiabatic evolution of light

abstract:
  We investigate the effect of nonlinearity in a system described by an
adiabatically evolving Hamiltonian. Experiments are conducted in a three-core
waveguide structure that is adiabatically varying with distance, in analogy to
the STIRAP process in atomic physics. In the linear regime, the system exhibits
an adiabatic power transfer between two waveguides which are not directly
coupled, with negligible power recorded in the intermediate coupling waveguide.
In the presence of nonlinearity the behavior of this configuration is
drastically altered and the adiabatic light passage is found to critically
depend on the excitation power. We show how this effect is related to the
destruction of the dark state formed in the STIRAP configuration.

categories: cond-mat.other nlin.PS physics.atom-ph quant-ph


title: Long-range epidemic spreading with immunization

abstract:
  We study the phase transition between survival and extinction in an epidemic
process with long-range interactions and immunization. This model can be viewed
as the well-known general epidemic process (GEP) in which nearest-neighbor
interactions are replaced by Levy flights over distances r which are
distributed as P(r) ~ r^(-d-sigma). By extensive numerical simulations we
confirm previous field-theoretical results obtained by Janssen et al. [Eur.
Phys. J. B7, 137 (1999)].


title: Data acquisition system for the MuLan muon lifetime experiment

abstract:
  We describe the data acquisition system for the MuLan muon lifetime
experiment at Paul Scherrer Institute. The system was designed to record muon
decays at rates up to 1 MHz and acquire data at rates up to 60 MB/sec. The
system employed a parallel network of dual-processor machines and repeating
acquisition cycles of deadtime-free time segments in order to reach the design
goals. The system incorporated a versatile scheme for control and diagnostics
and a custom web interface for monitoring experimental conditions.


title: Methane present in an extrasolar planet atmosphere

abstract:
  Molecules present in exoplanetary atmospheres are expected to strongly
influence the atmospheric radiation balance, trace dynamical and chemical
processes, and indicate the presence of disequilibrium effects. Since molecules
have the potential to reveal the exoplanet atmospheric conditions and
chemistry, searching for them is a high priority. The rotational-vibrational
transition bands of water, carbon monoxide, and methane are anticipated to be
the primary sources of non-continuum opacity in hot-Jovian planets. Since these
bands overlap in wavelength, and the corresponding signatures from them are
weak, decisive identification requires precision infrared spectroscopy. Here we
report on a near-infrared transmission spectrum of the planet HD 189733b
showing the presence of methane. Additionally, a resolved water-vapour band at
1.9 microns confirms the recent claim of water in this object. On
thermochemical grounds, carbon-monoxide is expected to be abundant in the upper
atmosphere of hot-Jovian exoplanets; thus the detection of methane rather than
carbon-monoxide in such a hot planet could signal the presence of a horizontal
chemical gradient away from the permanent dayside, or it may imply an
ill-understood photochemical mechanisms that leads to an enhancement of
methane.


title:
Far-from-constant mean curvature solutions of Einstein's constraint
  equations with positive Yamabe metrics

abstract:
  In this article we develop some new existence results for the Einstein
constraint equations using the Lichnerowicz-York conformal rescaling method.
The mean extrinsic curvature is taken to be an arbitrary smooth function
without restrictions on the size of its spatial derivatives, so that it can be
arbitrarily far from constant. The rescaled background metric belongs to the
positive Yamabe class, and the freely specifiable part of the data given by the
traceless-transverse part of the rescaled extrinsic curvature and the matter
fields are taken to be sufficiently small, with the matter energy density not
identically zero. Using topological fixed-point arguments and global barrier
constructions, we then establish existence of solutions to the constraints. Two
recent advances in the analysis of the Einstein constraint equations make this
result possible: A new type of topological fixed-point argument without
smallness conditions on spatial derivatives of the mean extrinsic curvature,
and a new construction of global super-solutions for the Hamiltonian constraint
that is similarly free of such conditions on the mean extrinsic curvature. For
clarity, we present our results only for strong solutions on closed manifolds.
However, our results also hold for weak solutions and for other cases such as
compact manifolds with boundary; these generalizations will appear elsewhere.
The existence results presented here for the Einstein constraints are
apparently the first such results that do not require smallness conditions on
spatial derivatives of the mean extrinsic curvature.


title: Generalized Model for $\Lambda$-Dark Energy

abstract:
  Einstein field equations under spherically symmetric space-times are
considered here in connection to dark energy investigation. A set of solutions
are obtained for a kinematical $\Lambda$ model, viz., $\Lambda \sim (\dot
a/a)^2$ without assuming any {\it a priori} value for the curvature constant
and the equation of state parameter $\omega$. Some interesting results, such as
the nature of cosmic density $\Omega$ and deceleration parameter $q$, have been
obtained with the consideration of two-fluid structure instead of usual
uni-fluid cosmological model.


title: Sequestration of ethane in the cryovolcanic subsurface of Titan

abstract:
  Saturn's largest satellite, Titan, has a thick atmosphere dominated by
nitrogen and methane. The dense orange-brown smog hiding the satellite's
surface is produced by photochemical reactions of methane, nitrogen and their
dissociation products with solar ultraviolet, which lead primarily to the
formation of ethane and heavier hydrocarbons. In the years prior to the
exploration of Titan's surface by the Cassini-Huygens spacecraft, the
production and condensation of ethane was expected to have formed a
satellite-wide ocean one kilometer in depth, assuming that it was generated
over the Solar system's lifetime. However, Cassini-Huygens observations failed
to find any evidence of such an ocean. Here we describe the main cause of the
ethane deficiency on Titan: cryovolcanic lavas regularly cover its surface,
leading to the percolation of the liquid hydrocarbons through this porous
material and its accumulation in subsurface layers built up during successive
methane outgassing events. The liquid stored in the pores may, combined with
the ice layers, form a stable ethane-rich clathrate reservoir, potentially
isolated from the surface. Even with a low open porosity of 10% for the
subsurface layers, a cryovolcanic icy crust less than 2300 m thick is required
to bury all the liquid hydrocarbons generated over the Solar system's lifetime.


title: Physical limits on computation by assemblies of allosteric proteins

abstract:
  Assemblies of allosteric proteins, nano-scale Brownian computers, are the
principle information processing devices in biology. The troponin C-troponin I
(TnC-TnI) complex, the Ca$^{2+}$-sensitive regulatory switch of the heart, is a
paradigm for Brownian computation. TnC and TnI specialize in sensing (reading)
and reporting (writing) tasks of computation. We have examined this complex
using a newly developed phenomenological model of allostery.
Nearest-neighbor-limited interactions among members of the assembly place
previously unrecognized constrains the topology of the system's free energy
landscape and generate degenerate transition probabilities. As a result,
signaling fidelity and deactivation kinetics can not be simultaneously
optimized. This trade-off places an upper limit on the rate of information
processing by assemblies of allosteric proteins that couple to a single ligand
chemical bath.


title: The lollipop graph is determined by its spectrum

abstract:
  An even (resp. odd) lollipop is the coalescence of a cycle of even (resp.
odd) length and a path with pendant vertex as distinguished vertex. It is known
that the odd lollipop is determined by its spectrum and the question is asked
by W. Haemers, X. Liu and Y. Zhang for the even lollipop. We revisit the proof
for odd lollipop, generalize it for even lollipop and therefore answer the
question. Our proof is essentially based on a method of counting closed walks.


title: Constructing dynamical twists over a non-abelian base

abstract:
  We give examples of dynamical twists in finite-dimensional Hopf algebras over
an arbitrary Hopf subalgebra. The construction is based on the categorical
approach of dynamical twists introduced by Donin and Mudrov.


title:
A Survey of Star Clusters in the M31 South-West Field. UBVRI Photometry
  and Multi-Band Maps

abstract:
  A new survey of star clusters in the South-West field of the M31 disk based
on the high resolution Subaru Suprime-Cam observations is presented. The UBVRI
aperture CCD photometry catalog of 285 objects (V < 20.5; 169 of them
identified for the first time) is provided. Each object is supplemented with
multi-band color maps presented in the electronic edition of the Astrophysical
Journal Supplement. Seventy seven star cluster candidates from the catalog are
located in the Hubble Space Telescope archive frames.


title: Equivariant cohomology and tensor categories

abstract:
  We propose the notion of a supercategory as an alternative approach to
supermathematics. We show that this setting is rich to carry out many of the
basic constructions of supermathematics. We also prove generalizations of a
number of results in equivariant cohomology, including the Chern-Weil theorem
for an arbitrary rigid Lie algebra object. For a quadratic Lie algebra object
we obtain a proof of the Duflo isomorphism along the lines of
Alekseev-Meinrenken, thereby generalizing their result to Lie superalgebras.


title:
Well-posedness and ill-posedness results for dissipative Benjamin-Ono
  equations

abstract:
  We study the Cauchy problem for the dissipative Benjamin-Ono equations
$u_t+\H u_{xx}+|D|^\alpha u+uu_x=0$ with $0\leq\alpha\leq 2$. When
$0\leq\alpha< 1$, we show the ill-posedness in $H^s(\R)$, $s\in\R$, in the
sense that the flow map $u_0\mapsto u$ (if it exists) fails to be $\C^2$ at the
origin. For $1<\alpha\leq 2$, we prove the global well-posedness in $H^s(\R)$,
$s>-\alpha/4$. It turns out that this index is optimal.


title: Finite size scaling for homogeneous pinning models

abstract:
  Pinning models are built from discrete renewal sequences by rewarding (or
penalizing) the trajectories according to their number of renewal epochs up to
time $N$, and $N$ is then sent to infinity. They are statistical mechanics
models to which a lot of attention has been paid both because they are very
relevant for applications and because of their {\sl exactly solvable
character}, while displaying a non-trivial phase transition (in fact, a
localization transition). The order of the transition depends on the tail of
the inter-arrival law of the underlying renewal and the transition is
continuous when such a tail is sufficiently heavy: this is the case on which we
will focus. The main purpose of this work is to give a mathematical treatment
of the {\sl finite size scaling limit} of pinning models, namely studying the
limit (in law) of the process close to criticality when the system size is
proportional to the correlation length.


title: The Super-Kamiokande Experiment

abstract:
  Super-Kamiokande is a 50 kiloton water Cherenkov detector located at the
Kamioka Observatory of the Institute for Cosmic Ray Research, University of
Tokyo. It was designed to study neutrino oscillations and carry out searches
for the decay of the nucleon. The Super-Kamiokande experiment began in 1996 and
in the ensuing decade of running has produced extremely important results in
the fields of atmospheric and solar neutrino oscillations, along with setting
stringent limits on the decay of the nucleon and the existence of dark matter
and astrophysical sources of neutrinos. Perhaps most crucially,
Super-Kamiokande for the first time definitively showed that neutrinos have
mass and undergo flavor oscillations. This chapter will summarize the published
scientific output of the experiment with a particular emphasis on the
atmospheric neutrino results.


title: Large scale vector modes and the first CMB temperature multipoles

abstract:
  Recent observations have pointed out various anomalies in some multipoles
(small $\ell $) of the cosmic microwave background (CMB). In this paper, it is
proved that some of these anomalies could be explained in the framework of a
modified concordance model, in which, there is an appropriate distribution of
vector perturbations with very large spatial scales. Vector modes are
associated with divergenceless (vortical) velocity fields. Here, the generation
of these modes is not studied in detail (it can be done "a posteriori"); on the
contrary, we directly look for the distributions of these vector modes which
lead to both alignments of the second and third multipoles and a planar
octopole. A general three-dimensional (3D) superimposition of vector
perturbations does not produce any alignment, but we have found rather general
2D superimpositions leading to anomalies similar to the observed ones; in these
2D cases, the angular velocity has the same direction at any point of an
extended region and, moreover, this velocity has the same distribution in all
the planes orthogonal to it. Differential rotations can be seen as particular
cases, in which, the angular velocity only depends on the distance to a
rotation axis. Our results strongly suggest that appropriate mixtures of scalar
and vector modes with very large spatial scales could explain the observed CMB
anomalies.


title: Decay Constants of Charged Pseudoscalar Mesons

abstract:
  We review here the physics of purely leptonic decays of pi-, K-, D+, Ds+, and
B- pseudoscalar mesons. The measured decay rates are related to the product of
the relevant weak interaction based CKM matrix element of the constituent
quarks and a strong interaction parameter related to the overlap of the quark
and anti-quark wave-functions in the meson, called the decay constant fP. The
interplay between theory and experiment is different for each particle.
Theoretical predictions that are necessary in the B sector can be tested, for
example, in the charm sector. One such measurement, that of fDs, differs from
the most precise unquenched lattice calculation and may indicate the presence
of new intermediate particles, or the theoretical prediction could be
misleading. The lighter pi and K mesons provide stringent comparisons due to
the accuracy of both the measurements and the theoretical predictions. This
review was prepared for the Particle Data Group's 2008 edition.


title:
Symmetry Classes of Spin and Orbital Ordered States in a t_{2g} Hubbard
  Model on a Two-dimensional Square Lattice

abstract:
  This paper presents symmetry classes of the Hartree-Fock (HF) solutions of
spin and orbital ordered states in a t_{2g} Hubbard model on a two-dimensional
square lattice. Using a group theoretical bifurcation theory of the Hartree
Fock equation, we obtained many types of broken symmetry solutions which
bifurcate from the normal state through one step transition in cases of
commensurate ordering vectors Q_0=(0,0), Q_1=(\pi,\pi), Q_2=(\pi,0) and
Q_3=(0,\pi). Each broken symmetry state is characterized by the presence of
local order parameters(LOP) at each lattice site: quadrupole moment
Q=(Q_2^2,Q_{12},Q_{23},Q_{31}), orbital angular momentum l=(l_1,l_2,l_3), spin
density s=(s^1,s^2,s^3), spin quadrupole moment Q^{\lambda}=(Q_2^{2\lambda},
Q_{12}^{\lambda},Q_{23}^{\lambda},Q_{31}^{\lambda}) and spin orbital angular
momentum l^{\lambda}=(l_1^{\lambda},l_2^{\lambda},l_3^{\lambda}) where
\lambda=1,2,3. We performed numerical calculations for some parameter sets.
Then we have found that many types of non-collinear magnetic orbital ordered
states having LOP:Q^{\lambda} and l^{\lambda} can be the ground state for these
parameter sets.


title:
A new red giant-based distance modulus of 13.3 Mpc to the Antennae
  galaxies and its consequences

abstract:
  The Antennae galaxies are the closest example of an ongoing major galaxy
merger, and thereby represent a unique laboratory for furthering the
understanding of the formation of exotic objects (e.g., tidal dwarf galaxies,
ultra-luminous X-ray sources, super-stellar clusters, etc). In a previous paper
HST/WFPC2 observations were used to demonstrate that the Antennae system might
be at a distance considerably less than that conventionally assumed in the
literature. Here we report new, much deeper HST/ACS imaging that resolves the
composite stellar populations, and most importantly, reveals a well-defined red
giant branch. The tip of this red giant branch (TRGB) is unambiguously detected
at Io(TRGB)=26.65 +/- 0.09 mag. Adopting the most recent calibration of the
luminosity of the TRGB then yields a distance modulus for the Antennae of
(m-M)o= 30.62 +/- 0.17 corresponding to a distance of 13.3 +/- 1.0 Mpc. This is
consistent with our earlier result, once the different calibrations for the
standard candle are considered. We briefly discuss the implications of this now
well determined shorter distance.


title: Monte Carlo without Chains

abstract:
  A sampling method for spin systems is presented. The spin lattice is written
as the union of a nested sequence of sublattices, all but the last with
conditionally independent spins, which are sampled in succession using their
marginals. The marginals are computed concurrently by a fast algorithm; errors
in the evaluation of the marginals are offset by weights. There are no Markov
chains and each sample is independent of the previous ones; the cost of a
sample is proportional to the number of spins (but the number of samples needed
for good statistics may grow with array size). The examples include the
Edwards-Anderson spin glass in three dimensions.


title: Testing additivity in nonparametric regression under random censorship

abstract:
  In this paper, we are concerned with nonparametric estimation of the
multivariate regression function in the presence of right censored data. More
precisely, we propose a statistic that is shown to be asymptotically normally
distributed under the additive assumption, and that could be used to test for
additivity in the censored regression setting.


title: Searches for Long-lived Particles at the Tevatron Collider

abstract:
  Several searches for long-lived particles have been performed using data from
p-pbar collisions from Run II at the Tevatron. In most cases, new analysis
techniques have been developed to carry out each search and/or estimate the
backgrounds. These searches expand the discovery potential of the CDF and D0
experiments to new physics that may have been missed by traditional search
techniques. This review discusses searches for (1) neutral, long-lived
particles decaying to muons, (2) massive, neutral, long-lived particles
decaying to a photon and missing energy, (3) stopped gluinos, and (4) charged
massive stable particles. It summarizes some of the theoretical and
experimental motivations for such searches.


title: Halphen pencils on quartic threefolds

abstract:
  For every smooth quartic threefold, we classify all pencils on it whose
general element is an irreducible surface birational to a smooth surface of
Kodaira dimension zero.


title:
HST NICMOS imaging of z~2, 24 micron-selected Ultraluminous Infrared
  Galaxies

abstract:
  We present Hubble Space Telescope NICMOS H-band imaging of 33 Ultraluminous
Infrared Galaxies (ULIRGs) at z~2 that were selected from the 24 micron catalog
of the Spitzer Extragalactic First Look Survey. The images reveal that at least
17 of the 33 objects are associated with interactions. Up to one fifth of the
sources in our sample could be minor mergers whereas only 2 systems are merging
binaries with luminosity ratio <=3:1, which is characteristic of local ULIRGs.
The rest-frame optical luminosities of the sources are of the order 10^10-10^11
L_sun and their effective radii range from 1.4 to 4.9 kpc. The most compact
sources are either those with a strong active nucleus continuum or those with a
heavy obscuration in the mid-infrared regime, as determined from Spitzer
Infra-Red Spectrograph data. The luminosity of the 7.7 micron feature produced
by polycyclic aromatic hydrocarbon molecules varies significantly among compact
systems whereas it is typically large for extended systems. A bulge-to-disk
decomposition performed for the 6 brightest (m_H<20) sources in our sample
indicates that they are best fit by disk-like profiles with small or negligible
bulges, unlike the bulge-dominated remnants of local ULIRGs. Our results
provide evidence that the interactions associated with ultraluminous infrared
activity at z~2 can differ from those at z~0.


title: The Formation of Polar Disk Galaxies

abstract:
  Polar Ring Galaxies, such as NGC4650A, are a class of galaxy which have two
kinematically distinct components that are inclined by almost 90 degrees to
each other. These striking galaxies challenge our understanding of how galaxies
form; the origin of their distinct components has remained uncertain, and the
subject of much debate. We use high-resolution cosmological simulations of
galaxy formation to show that Polar Ring Galaxies are simply an extreme example
of the angular moment misalignment that occurs during the hierarchical
structure formation characteristic of Cold Dark Matter cosmology. In our model,
Polar Ring Galaxies form through the continuous accretion of gas whose angular
momentum is misaligned with the central galaxy.


title:
Two universal 3-quantifier representations of recursively enumerable
  sets

abstract:
  It is proved that all recursively enumerable sets of natural numbers can be
represented by arithmetic formulas (of two kinds) with only 3 quantifiers.


title: Generalized CMB initial conditions with pre-equality magnetic fields

abstract:
  The most general initial conditions of CMB anisotropies, compatible with the
presence of pre-equality magnetic fields, are derived. When the plasma is
composed by photons, baryons, electrons, CDM particles and neutrinos, the
initial data of the truncated Einstein-Boltzmann hierarchy contemplate one
magnetized adiabatic mode and four (magnetized) non-adiabatic modes. After
obtaining the analytical form of the various solutions, the Einstein-Boltzmann
hierarchy is numerically integrated for the corresponding sets of initial data.
The TT, TE and EE angular power spectra are illustrated and discussed for the
magnetized generalization of the CDM-radiation mode, of the baryon-radiation
mode and of the non-adiabatic mode of the neutrino sector. Mixtures of initial
conditions are examined by requiring that the magnetized adiabatic mode
dominates over the remaining non-adiabatic contributions. In the latter case,
possible degeneracies between complementary sets of initial data might be
avoided through the combined analysis of the TT, TE and EE angular power
spectra at high multipoles (i.e. $\ell >1000$).


title: Dynamical instabilities in a simple minority game with discounting

abstract:
  We explore the effect of discounting and experimentation in a simple model of
interacting adaptive agents. Agents belong to either of two types and each has
to decide whether to participate a game or not, the game being profitable when
there is an excess of players of the other type. We find the emergence of large
fluctuations as a result of the onset of a dynamical instability which may
arise discontinuously (increasing the discount factor) or continuously
(decreasing the experimentation rate). The phase diagram is characterized in
detail and noise amplification close to a bifurcation point is identified as
the physical mechanism behind the instability.


title: Unusual percolation in simple small-world networks

abstract:
  We present an exact solution of percolation in a generalized class of
Watts-Strogatz graphs defined on a 1-dimensional underlying lattice. We find a
non-classical critical point in the limit of the number of long-range bonds in
the system going to zero, with a discontinuity in the percolation probability
and a divergence in the mean finite-cluster size. We show that the critical
behavior falls into one of three regimes depending on the proportion of
occupied long-range to unoccupied nearest-neighbor bonds, with each regime
being characterized by different critical exponents. The three regimes can be
united by a single scaling function around the critical point. These results
can be used to identify the number of long-range links necessary to secure
connectivity in a communication or transportation chain. As an example, we can
resolve the communication problem in a game of "telephone".


title: Genetic Code: Four-Codon and Non-Four-Codon Degeneracy

abstract:
  In this work it is shown that 20 canonical amino acids (AAs) within genetic
code appear to be a whole system with strict distinction in Genetic Code Table
(GCT) into some different quantums: 20, 23, 61 amino acid molecules. These
molecules distinction is followed by specific balanced atom number and/or
nucleon number distinctions within those molecules. In this second version two
appendices are added; also a new version of Periodic system of numbers, whose
first verson is given in arXiv:1107.1998 [q-bio.OT].


title: A stitch in time: Efficient computation of genomic DNA melting bubbles

abstract:
  Background: It is of biological interest to make genome-wide predictions of
the locations of DNA melting bubbles using statistical mechanics models.
Computationally, this poses the challenge that a generic search through all
combinations of bubble starts and ends is quadratic.
  Results: An efficient algorithm is described, which shows that the time
complexity of the task is O(NlogN) rather than quadratic. The algorithm
exploits that bubble lengths may be limited, but without a prior assumption of
a maximal bubble length. No approximations, such as windowing, have been
introduced to reduce the time complexity. More than just finding the bubbles,
the algorithm produces a stitch profile, which is a probabilistic graphical
model of bubbles and helical regions. The algorithm applies a probability peak
finding method based on a hierarchical analysis of the energy barriers in the
Poland-Scheraga model.
  Conclusions: Exact and fast computation of genomic stitch profiles is thus
feasible. Sequences of several megabases have been computed, only limited by
computer memory. Possible applications are the genome-wide comparisons of
bubbles with promotors, TSS, viral integration sites, and other melting-related
regions.


title: Lefschetz Properties and Basic Constructions on Simplicial Spheres

abstract:
  The well known $g$-conjecture for homology spheres follows from the stronger
conjecture that the face ring over the reals of a homology sphere, modulo a
linear system of parameters, admits the strong-Lefschetz property. We prove
that the strong-Lefschetz property is preserved under the following
constructions on homology spheres: join, connected sum, and stellar
subdivisions. The last construction is a step towards proving the
$g$-conjecture for piecewise-linear spheres.


title: Average-Case Analysis of Online Topological Ordering

abstract:
  Many applications like pointer analysis and incremental compilation require
maintaining a topological ordering of the nodes of a directed acyclic graph
(DAG) under dynamic updates. All known algorithms for this problem are either
only analyzed for worst-case insertion sequences or only evaluated
experimentally on random DAGs. We present the first average-case analysis of
online topological ordering algorithms. We prove an expected runtime of O(n^2
polylog(n)) under insertion of the edges of a complete DAG in a random order
for the algorithms of Alpern et al. (SODA, 1990), Katriel and Bodlaender (TALG,
2006), and Pearce and Kelly (JEA, 2006). This is much less than the best known
worst-case bound O(n^{2.75}) for this problem.


title: On Ueno's Conjecture K

abstract:
  We show that if $X$ is a smooth complex projective variety with Kodaira
dimension $0$ then the Kodaira dimension of a general fiber of its Albanese map
is at most $h^0(\Omega ^1 _X)$.


title: Electroweak precision constraints on the Lee-Wick Standard Model

abstract:
  We perform an analysis of the electroweak precision observables in the
Lee-Wick Standard Model. The most stringent restrictions come from the S and T
parameters that receive important tree level and one loop contributions. In
general the model predicts a large positive S and a negative T. To reproduce
the electroweak data, if all the Lee-Wick masses are of the same order, the
Lee-Wick scale is of order 5 TeV. We show that it is possible to find some
regions in the parameter space with a fermionic state as light as 2.4-3.5 TeV,
at the price of rising all the other masses to be larger than 5-8 TeV. To
obtain a light Higgs with such heavy resonances a fine-tuning of order a few
per cent, at least, is needed. We also propose a simple extension of the model
including a fourth generation of Standard Model fermions with their Lee-Wick
partners. We show that in this case it is possible to pass the electroweak
constraints with Lee-Wick fermionic masses of order 0.4-1.5 TeV and Lee-Wick
gauge masses of order 3 TeV.


title: A Few Splitting Criteria for Vector Bundles

abstract:
  We prove a few splitting criteria for vector bundles on a quadric
hypersurface and Grassmannians. We give also some cohomological splitting
conditions for rank 2 bundles on multiprojective spaces. The tools are monads
and a Beilinson's type spectral sequence generalized by Costa and Mir\'o-Roig.


title:
Derivation of the relativistic "proper-time" quantum evolution equations
  from Canonical Invariance

abstract:
  Based on 1) the spectral resolution of the energy operator; 2) the linearity
of correspondence between physical observables and quantum Hermitian operators;
3) the definition of conjugate coordinate-momentum variables in classical
mechanics; and 4) the fact that the physical point in phase space remains
unchanged under (canonical) transformations between one pair of conjugate
variables to another, we are able to show that <t_s|E_s>, the proper-time
rest-energy transformation matrices, are given as a*exp[-iE_s t_s/\hbar], from
which we obtain the proper-time rest -energy evolution equation
i\hbar{\partial/\partial t_s} |Psi>= \hat{E_s}|Psi>. For special relativistic
situations this equation can be reduced to the usual i\hbar{\partial/\partial
t}|Psi>=\hat{E}|Psi> dynamical equations, where t is the "reference time" and E
is the total energy. Extension of these equations to accelerating frames is
then provided.


title:
Nonuniversal transmission phase lapses through a quantum dot: An
  exact-diagonalization of the many-body transport problem

abstract:
  Systematic trends of nonuniversal behavior of electron transmission phases
through a quantum dot, with no phase lapse for the transition N=1 -> N=2 and a
lapse of pi for the N=2 -> N=3 transition, are predicted, in agreement with
experiments, from many-body transport calculations involving exact
diagonalization of the dot Hamiltonian. The results favor shape anisotropy of
the dot and strong e-e repulsion with consequent electron localization, showing
dependence on spin configurations and the participation of excited doorway
transmission channels.


title:
Quantum radiations from exciton condensate in Electron-Hole Bilayer
  Systems

abstract:
  Superfluid has been realized in Helium-4, Helium-3 and ultra-cold atoms. It
has been widely used in making high-precision devices and also in cooling
various systems. There have been extensive experimental search for possible
exciton superfluid (ESF) in semiconductor electron-hole bilayer (EHBL) systems
below liquid Helium temperature. However, exciton superfluid are meta-stable
and will eventually decay through emitting photons. Here we study quantum
nature of photons emitted from the excitonic superfluid (ESF) phase in the
semiconductor EHBL and find that the light emitted from the excitonic
superfluid has unique and unusual features not shared by any other atomic or
condensed matter systems. We show that the emitted photons along the direction
perpendicular to the layer are in a coherent state, those along all tilted
directions are in a two modes squeezed state. We determine the two mode
squeezing spectra, the angle resolved power spectrum, the line shapes of both
the momentum distribution curve (MDC) and the energy distribution curve (EDC).
  From the two photon correlation functions, we find there are photon bunching,
the photo-count statistics is super-Poissonian. We discuss how several
important parameters such as the chemical potential, the exciton decay rate,
the quasiparticle energy spectrum and the dipole-dipole interaction strength
between the excitons in our theory can be extracted from the experimental data
and comment on available experimental data on both EDC and MDC.

categories: cond-mat.mtrl-sci cond-mat.mes-hall physics.optics quant-ph


title: Coherence and metamagnetism in the two-dimensional Kondo lattice model

abstract:
  We report the results of dynamical mean field calculations for the metallic
Kondo lattice model subject to an applied magnetic field. High-quality spectral
functions reveal that the picture of rigid, hybridized bands, Zeeman-shifted in
proportion to the field strength, is qualitatively correct. We find evidence of
a zero-temperature magnetization plateau, whose onset coincides with the
chemical potential entering the spin up hybridization gap. The plateau appears
at the field scale predicted by (static) large-N mean field theory and has a
magnetization value consistent with that of x=1-n_c spin-polarized heavy holes,
where n_c < 1 is the conduction band filling of the noninteracting system. We
argue that the emergence of the plateau at low temperature marks the onset of
quasiparticle coherence.


title: The Phase Transition to Eternal Inflation

abstract:
  For slow-roll inflation we study the phase transition to the eternal regime.
Starting from a finite inflationary volume, we consider the volume of the
universe at reheating as order parameter. We show that there exists a critical
value for the classical inflaton speed, \dot\phi^2/H^4 = 3/(2 \pi^2), where the
probability distribution for the reheating volume undergoes a sharp transition.
In particular, for sub-critical inflaton speeds all distribution moments become
infinite. We show that at the same transition point the system develops a
non-vanishing probability of having a strictly infinite reheating volume, while
retaining a finite probability for finite values. Our analysis represents the
exact quantum treatment of the system at lowest order in the slow-roll
parameters and H^2/M_Pl^2.


title: Large Scale Structure as a Probe of Gravitational Slip

abstract:
  A new time-dependent, scale-independent parameter, \varpi, is employed in a
phenomenological model of the deviation from General Relativity in which the
Newtonian and longitudinal gravitational potentials slip apart on cosmological
scales as dark energy, assumed to be arising from a new theory of gravitation,
appears to dominate the universe. A comparison is presented between \varpi and
other parameterized post-Friedmannian models in the literature. The effect of
\varpi on the cosmic microwave background anisotropy spectrum, the growth of
large scale structure, the galaxy weak-lensing correlation function, and
cross-correlations of cosmic microwave background anisotropy with galaxy
clustering are illustrated. Cosmological models with conventional maximum
likelihood parameters are shown to find agreement with a narrow range of
gravitational slip.


title: The L_X--M relation of Clusters of Galaxies

abstract:
  We present a new measurement of the scaling relation between X-ray luminosity
and total mass for 17,000 galaxy clusters in the maxBCG cluster sample.
Stacking sub-samples within fixed ranges of optical richness, N_200, we measure
the mean 0.1-2.4 keV X-ray luminosity, <L_X>, from the ROSAT All-Sky Survey.
The mean mass, <M_200>, is measured from weak gravitational lensing of SDSS
background galaxies (Johnston et al. 2007). For 9 <= N_200 < 200, the data are
well fit by a power-law, <L_X>/10^42 h^-2 erg/s = (12.6+1.4-1.3 (stat) +/- 1.6
(sys)) (<M_200>/10^14 h^-1 M_sun)^1.65+/-0.13. The slope agrees to within 10%
with previous estimates based on X-ray selected catalogs, implying that the
covariance in L_X and N_200 at fixed halo mass is not large. The luminosity
intercent is 30%, or 2\sigma, lower than determined from the X-ray flux-limited
sample of Reiprich & Bohringer (2002), assuming hydrostatic equilibrium. This
difference could arise from a combination of Malmquist bias and/or systematic
error in hydrostatic mass estimates, both of which are expected. The intercept
agrees with that derived by Stanek et al. (2006) using a model for the
statistical correspondence between clusters and halos in a WMAP3 cosmology with
power spectrum normalization sigma_8 = 0.85. Similar exercises applied to
future data sets will allow constraints on the covariance among optical and hot
gas properties of clusters at fixed mass.


title: Affine tangles and irreducible exotic sheaves

abstract:
  We construct a weak representation of the category of framed affine tangles
on a disjoint union of triangulated categories ${\mathcal D}_{2n}$. The
categories we use are that of coherent sheaves on Springer fibers over a
nilpotent element of $sl_{2n}$ with two equal Jordan blocks. This
representation allows us to enumerate the irreducible objects in the heart of
the exotic $t$-structure on ${\mathcal D}_{2n}$ by crossingless matchings of
$2n$ points on a circle. We also describe the algebra of endomorphisms of the
direct sum of the irreducible objects.


title:
The infrared spectra of very large, compact, highly symmetric,
  polycyclic aromatic hydrocarbons (PAHs)

abstract:
  The mid-infrared spectra of large PAHs ranging from C54H18 to C130H28 are
determined computationally using Density Functional Theory. Trends in the band
positions and intensities as a function of PAH size, charge and geometry are
discussed. Regarding the 3.3, 6.3 and 11.2 micron bands similar conclusions
hold as with small PAHs.
  This does not hold for the other features. The larger PAH cations and anions
produce bands at 7.8 micron and, as PAH sizes increases, a band near 8.5 micron
becomes prominent and shifts slightly to the red. In addition, the average
anion peak falls slightly to the red of the average cation peak. The similarity
in behavior of the 7.8 and 8.6 micron bands with the astronomical observations
suggests that they arise from large, cationic and anionic PAHs, with the
specific peak position and profile reflecting the PAH cation to anion
concentration ratio and relative intensities of PAH size. Hence, the broad
astronomical 7.7 micron band is produced by a mixture of small and large PAH
cations and anions, with small and large PAHs contributing more to the 7.6 and
7.8 micron component respectively.
  For the CH out-of-plane vibrations, the duo hydrogens couple with the solo
vibrations and produce bands that fall at wavelengths slightly different than
their counterparts in smaller PAHs. As a consequence, previously deduced PAH
structures are altered in favor of more compact and symmetric forms. In
addition, the overlap between the duo and trio bands may reproduce the
blue-shaded 12.8 micron profile.


title: A note on closed 3-braids

abstract:
  Knots and links which are closed 3-braids are a very special class. Like
2-bridge knots and links, they are simple enough to admit a complete
classification. At the same time they are rich enough to serve as a source of
examples on which, with luck, a researcher may be able to test various
conjectures. The goal of this review article is to gather together, in one
place, some of the tools that are special to knots and links of braid index 3,
in a form that could be useful for those who have a need to calculate, and need
to know precisely all the exceptional cases. We also use it as an opportunity
to review what is known and suggest some open questions.


title: Galaxy Bulges As Tests of CDM vs MOND in Strong Gravity

abstract:
  The tight correlation between galaxy bulges and their central black hole
masses likely emerges in a phase of rapid collapse and starburst at high
redshift, due to the balance of gravity on gas with the feedback force from
starbursts and the wind from the black hole; the average gravity on per unit
mass of gas is ~ 2 x 10^-10 m/sec^2 during the star burst phase. This level of
gravity could come from the real r^{-1} cusps of Cold Dark Matter (CDM) halos,
but the predicted gravity would have a large scatter due to dependence on
cosmological parameters and formation histories. Better agreement is found with
the gravity from the scalar field in some co-variant versions of MOND, which
can create the mirage of a Newtonian effective dark halo of density Pi r^{-1}
near the center, where the characteristic surface density Pi=130alpha^{-1} Msun
pc^{-2} and alpha is a fundamental constant of order unity fixed by the
Lagrangian of the co-variant theory if neglecting environmental effects.
  We show with a toy analytical model and a hydrodynamical simulation that a
constant background gravity due to MOND/TeVeS scalar field implies a critical
pressure synchronizing starbursts and the formation of galaxy bulges and
ellipticals. A universal threshold for the formation of the brightest regions
of galaxies in a MONDian universe suggests that the central BHs, bulges and
ellipticals would respect tight correlations like the M_{bulge}-M_{BH}-sigma
relations. In general MOND tends to produce tight correlations in galaxy
properties because its effective halo has less freedom and scatter than CDM
halos.


title: Giant AGN Flares and Cosmic Ray Bursts

abstract:
  We predict a new class of very intense, short-duration AGN flares capable of
accelerating the highest energy cosmic rays, resulting from the tidal
disruption of a star or from a disk instability. The rate and power of these
flares readily explains the observed flux and density statistics of UHECRs. The
photon bursts produced by the predicted AGN flares are discussed; they may soon
be detectable. Observations are shown to exclude that continuous jets of
powerful Active Galactic Nuclei are the sole source of ultrahigh energy cosmic
rays; the stringent requirements for Gamma Ray Bursts to be the source are
delineated.


title:
Exactly solvable `discrete' quantum mechanics; shape invariance,
  Heisenberg solutions, annihilation-creation operators and coherent states

abstract:
  Various examples of exactly solvable `discrete' quantum mechanics are
explored explicitly with emphasis on shape invariance, Heisenberg operator
solutions, annihilation-creation operators, the dynamical symmetry algebras and
coherent states. The eigenfunctions are the (q-)Askey-scheme of hypergeometric
orthogonal polynomials satisfying difference equation versions of the
Schr\"odinger equation. Various reductions (restrictions) of the symmetry
algebra of the Askey-Wilson system are explored in detail.

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


title:
New Extensions of Pairing-based Signatures into Universal (Multi)
  Designated Verifier Signatures

abstract:
  The concept of universal designated verifier signatures was introduced by
Steinfeld, Bull, Wang and Pieprzyk at Asiacrypt 2003. These signatures can be
used as standard publicly verifiable digital signatures but have an additional
functionality which allows any holder of a signature to designate the signature
to any desired verifier. This designated verifier can check that the message
was indeed signed, but is unable to convince anyone else of this fact. We
propose new efficient constructions for pairing-based short signatures. Our
first scheme is based on Boneh-Boyen signatures and its security can be
analyzed in the standard security model. We prove its resistance to forgery
assuming the hardness of the so-called strong Diffie-Hellman problem, under the
knowledge-of-exponent assumption. The second scheme is compatible with the
Boneh-Lynn-Shacham signatures and is proven unforgeable, in the random oracle
model, under the assumption that the computational bilinear Diffie-Hellman
problem is untractable. Both schemes are designed for devices with constrained
computation capabilities since the signing and the designation procedure are
pairing-free. Finally, we present extensions of these schemes in the multi-user
setting proposed by Desmedt in 2003.


title: Surfaces obtained from CP^(N-1) sigma models

abstract:
  In this paper, the Weierstrass technique for harmonic maps S^2 -> CP^(N-1) is
employed in order to obtain surfaces immersed in multidimensional Euclidean
spaces. It is shown that if the CP^(N-1) model equations are defined on the
sphere S^2 and the associated action functional of this model is finite, then
the generalized Weierstrass formula for immersion describes conformally
parametrized surfaces in the su(N) algebra. In particular, for any holomorphic
or antiholomorphic solution of this model the associated surface can be
expressed in terms of an orthogonal projector of rank (N-1). The implementation
of this method is presented for two-dimensional conformally parametrized
surfaces immersed in the su(3) algebra. The usefulness of the proposed approach
is illustrated with examples, including the dilation-invariant meron-type
solutions and the Veronese solutions for the CP^2 model. Depending on the
location of the critical points (zeros and poles) of the first fundamental form
associated with the meron solution, it is shown that the associated surfaces
are semi-infinite cylinders. It is also demonstrated that surfaces related to
holomorphic and mixed Veronese solutions are immersed in R^8 and R^3,
respectively.


title:
Real-time diagrammatic approach to transport through interacting quantum
  dots with normal and superconducting leads

abstract:
  We present a real-time diagrammatic theory for transport through interacting
quantum dots tunnel coupled to normal and superconducting leads. Our
formulation describes both the equilibrium and non-equilibrium superconducting
proximity effect in a quantum dot. We study a three-terminal transistor
geometry, consisting of a single-level quantum dot tunnel coupled to two
phase-biased superconducting leads and one voltage-biased normal lead. We
compute both the Josephson current between the two superconductors and the
Andreev current in the normal lead, and analyze their switching on and off as
well as transitions between 0- and $\pi$-states as a function of gate and bias
voltage. For the limit of large superconducting gaps in the leads, we describe
the formation of Andreev bound states within an exact resummation of all orders
in the tunnel coupling to the superconducting leads, and discuss their
signature in the non-equilibrium Josephson- and Andreev- current and the
quantum-dot charge.


title: $p$-Adic multiresolution analysis and wavelet frames

abstract:
  We study $p$-adic multiresolution analyses (MRAs). A complete
characterisation of test functions generating MRAs (scaling functions) is
given. We prove that only 1-periodic test functions may be taken as orthogonal
scaling functions. We also suggest a method for the construction of wavelet
functions and prove that any wavelet function generates a $p$-adic wavelet
frame.


title: Absolutely continuous spectrum of a Schr\"odinger operator on a tree

abstract:
  We give sufficient conditions for the presence of the absolutely continuous
spectrum of a Schr\"odinger operator on a regular rooted tree without loops
(also called regular Bethe lattice or Cayley tree).


title: Ahlfors' currents in higher dimension

abstract:
  We consider a nondegenerate holomorphic map $f: V \mapsto X$ where $(X,
\omega)$ is a compact hermitian manifold of dimension higher or equal to $k$
and $V$ is an open connected complex manifold of dimension $k$. In this article
we give criteria which permit to construct Ahlfors' currents in $X$.


title: On the Y555 complex reflection group

abstract:
  We give a computer-free proof of a theorem of Basak, describing the group
generated by 16 complex reflections of order 3, satisfying the braid and
commutation relations of the Y555 diagram. The group is the full isometry group
of a certain lattice of signature (13,1) over the Eisenstein integers Z[cube
root of 1]. Along the way we enumerate the cusps of this lattice and classify
the root and Niemeier lattices over this ring.


title: The Gram determinant of the type B Temperley-Lieb algebra

abstract:
  In this paper, we solve a problem posed by Rodica Simion regarding type B
Gram determinants. We present this in a fashion influenced by the work of
W.B.R.Lickorish on Witten-Reshetikhin-Turaev invariants of 3-manifolds. The
roots of the determinant were predicted by Dabkowski and Przytycki, and the
complete factorization was conjectured by Gefry Barad. We will give a detailed
history of this problem in a sequel paper in which we also plan to address
other related questions by Simion, and connect the problem to
Frenkel-Khovanov's work.


title: U(3)-Flavor Nonet Scalar as an Origin of the Flavor Mass Spectra

abstract:
  According to an idea that the quark and lepton mass spectra originate in a
VEV structure of a U(3)-flavor nonet scalar \Phi, the mass spectra of the
down-quarks and charged leptons are investigated. The U(3) flavor symmetry is
spontaneously and completely broken by non-zero and non-degenerated VEVs of
$\Phi$, without passing any subgroup of U(3). The ratios
(m_e+m_\mu+m_\tau)/(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_\tau})^2 and \sqrt{m_e
m_\mu m_\tau}/(\sqrt{m_e}+\sqrt{m_\mu}+\sqrt{m_\tau})^3 are investigated based
on a toy model.


title: Auslander Bounds and Homological Conjectures

abstract:
  Inspired by recent works on rings satisfying Auslander's conjecture, we study
invariants, which we call Auslander bounds, and prove that they have strong
relations to some homological conjectures.


title:
Coupled and Extended Quintessence: theoretical differences and structure
  formation

abstract:
  The case of a coupling between dark energy and matter (Coupled Quintessence)
or gravity (Extended Quintessence) has recently attracted a deep interest and
has been widely investigated both in the Einstein and in the Jordan frames (EF,
JF), within scalar tensor theories. Focusing on the simplest models proposed so
far, in this paper we study the relation existing between the two scenarios,
isolating the Weyl scaling which allows to express them in the EF and JF.
Moreover, we perform a comparative study of the behavior of linear
perturbations in both scenarios, which turn out to behave in a markedly
different way. In particular, while the clustering is enhanced in the
considered CQ models with respect to the corresponding Quintessence ones where
the coupling is absent and to the ordinary cosmologies with a Cosmological
Constant and Cold Dark Matter (LCDM), structures in EQ models may grow slower.
This is likely to have direct consequences on the inner properties of
non-linear structures, like cluster concentration, as well as on the weak
lensing shear on large scales. Finally, we specialize our study for interfacing
linear dynamics and N-body simulations in these cosmologies, giving a recipe
for the corrections to be included in N-body codes in order to take into
account the modifications to the expansion rate, growth of structures, and
strength of gravity.


title: Evolution of displacements and strains in sheared amorphous solids

abstract:
  The local deformation of two-dimensional Lennard-Jones glasses under imposed
shear strain is studied via computer simulations. Both the mean squared
displacement and mean squared strain rise linearly with the length of the
strain interval $\Delta \gamma$ over which they are measured. However, the
increase in displacement does not represent single-particle diffusion. There
are long-range spatial correlations in displacement associated with slip lines
with an amplitude of order the particle size. Strong dependence on system size
is also observed. The probability distributions of displacement and strain are
very different. For small $\Delta \gamma$ the distribution of displacement has
a plateau followed by an exponential tail. The distribution becomes Gaussian as
$\Delta \gamma$ increases to about .03. The strain distributions consist of
sharp central peaks associated with elastic regions, and long exponential tails
associated with plastic regions. The latter persist to the largest $\Delta
\gamma$ studied.


title: Carter subgroups of finite groups

abstract:
  In the paper it is proven that Carter subgroups of a finite group are
conjugate. A complete classification of Carter subgroups in finite almost
simple groups is also obtained.


title: Does the period of BE Lyncis really vary?

abstract:
  New photometric series of BE Lyncis are presented. With template curve
fitting we re-determined the $O-C$ for BE Lyncis. The phase shift diagram is
apparently constant, disproving the suspected period variations of BE Lyn.


title: On Nova Scorpii 2007 N.1 (V1280 Sco)

abstract:
  We present the results of our photometric and spectroscopic observations of
Nova Sco 2007 N.1 (V1280 Sco). The photometric data was represented by a single
data point in the light curve since the observation was carried out only for
one night. The spectra cover two different phases of the object's evolution
during the outburst, i.e. pre-maximum and post-maximum. Measurements of the
P-Cygni profile on Na I 'D' line (5889 \AA) was derived as the velocity of
shell expansion, yielding $1567.43 \pm 174.14$ km s$^{-1}$. We conclude that
V1280 Sco is a fast Fe II-type nova.


title: Equilibrium Constant as Solution to the Open Chemical Systems

abstract:
  According to contemporary views, equilibrium constant is relevant only to
true thermodynamic equilibria in isolated systems with one chemical reaction.
The paper presents a novel formula that ties-up equilibrium constant and
chemical system composition at any state, isolated or open as well. Extending
the logarithmic logistic map of the Discrete Thermodynamics of Chemical
Equilibria, this formula maps the system population at isolated equilibrium
into the population at any open equilibrium at p,T=const, using equilibrium
constant as a measure. Real chemical systems comprise multiple subsystems;
given the resources are limited, joint solution to the set of such expressions,
each relevant to a specific subsystem, gives equilibrium composition for each
of them. This result means a fundamental break through in the open systems
thermodynamics and leads to formerly unknown opportunities in the analysis of
real chemical objects.


title:
Equilibrium Geometries, Reaction Pathways, and Electronic Structures of
  Ethanol Adsorbed on the Si (111) Surface

abstract:
  Equilibrium atomic configurations and electron energy structure of ethanol
adsorbed on the Si (111) surface are studied by the first-principles density
functional theory. Geometry optimization is performed by the total energy
minimization method. Several equilibrium atomic configurations of ethanol, both
undissociated and dissociated, on the Si (111) surface are found. Reaction
pathways and predicted transition states are discussed in comparison with
available experimental data in terms of the feasibility of the reactions
occurring. Analysis of atom and orbital resolved projected density of states
indicate substantial modifications of the Si surface valence and conduction
bands due to the adsorption of ethanol affecting the electrical properties of
the surface.


title: Ultracold dense gas of deeply bound heteronuclear molecules

abstract:
  Recently, the quest for an ultracold and dense ensemble of polar molecules
has attracted strong interest. Polar molecules have bright prospects for novel
quantum gases with long-range and anisotropic interactions, for quantum
information science, and for precision measurements. However, high-density
clouds of ultracold polar molecules have so far not been produced. Here, we
report a key step towards this goal. Starting from an ultracold dense gas of
heteronuclear 40K-87Rb Feshbach molecules with typical binding energies of a
few hundred kHz and a negligible dipole moment, we coherently transfer these
molecules into a vibrational level of the ground-state molecular potential
bound by >10 GHz. We thereby increase the binding energy and the expected
dipole moment of the 40K-87Rb molecules by more than four orders of magnitude
in a single transfer step. Starting with a single initial state prepared with
Feshbach association, we achieve a transfer efficiency of 84%. While dipolar
effects are not yet observable, the presented technique can be extended to
access much more deeply bound vibrational levels and ultimately those
exhibiting a significant dipole moment. The preparation of an ultracold quantum
gas of polar molecules might therefore come within experimental reach.


title: Properties of element orders in covers for L(n,q) and U(n,q)

abstract:
  We show that if a finite simple group G isomorphic to PSL(n,q) or PSU(n,q),
where either $n\ne 4$, or q is prime or even, acts on a vector space over a
field of the defining characteristic of G, then the corresponding semidirect
product contains an element whose order is distinct from every element order of
G. As a consequence, we prove that the group PSL(n,q), where $n\ne 4$ or q
prime or even, is recognizable by spectrum from its covers thus giving a
partial positive answer to Problem 14.60 from the Kourovka notebook.


title: On the Accuracy of Galileo's Observations

abstract:
  Galileo Galilei had sufficient skill as an observer and instrument builder to
be able to measure the positions and apparent sizes of objects seen through his
telescopes to an accuracy of 2" or better. However, Galileo had no knowledge of
wave optics, so when he was measuring stellar apparent sizes he was producing
very accurate measurements of diffraction artifacts and not physical bodies.


title: The structure of a tridiagonal pair

abstract:
  Let $K$ denote a field and let $V$ denote a vector space over $K$ with finite
positive dimension. We consider a pair of linear transformations $A:V \to V$
and $A^*:V \to V$ that satisfy the following conditions: (i) each of $A,A^*$ is
diagonalizable; (ii) there exists an ordering $\{V_i\}_{i=0}^d$ of the
eigenspaces of $A$ such that $A^* V_i \subseteq V_{i-1} + V_i + V_{i+1}$ for $0
\leq i \leq d$, where $V_{-1}=0$ and $V_{d+1}=0$; (iii) there exists an
ordering $\{V^*_i\}_{i=0}^\delta$ of the eigenspaces of $A^*$ such that $A
V^*_i \subseteq V^*_{i-1} + V^*_i + V^*_{i+1}$ for $0 \leq i \leq \delta$,
where $V^*_{-1}=0$ and $V^*_{\delta+1}=0$; (iv)there is no subspace $W$ of $V$
such that $AW \subseteq W$, $A^* W \subseteq W$, $W \neq 0$, $W \neq V$. We
call such a pair a tridiagonal pair on $V$. It is known that $d=\delta$ and for
$0 \leq i \leq d$ the dimensions of $V_i, V_{d-i}, V^*_i, V^*_{d-i}$ coincide.
In this paper we show that the following (i)--(iv) hold provided that $K$ is
algebraically closed: (i) Each of $V_0$, $V^*_0$, $V_d$, $V^*_d$ has dimension
1. (ii) There exists a nondegenerate symmetric bilinear form $(,)$ on $V$ such
that $(Au,v)=(u,Av)$ and $(A^*u,v)=(u,A^*v)$ for all $u,v \in V$. (iii) There
exists a unique anti-automorphism of $End(V)$ that fixes each of $A,A^*$. (iv)
The pair $A,A^*$ is determined up to isomorphism by the data
$(\{\th_i\}_{i=0}^d; \{\th^*_i\}_{i=0}^d; \{\zeta_i\}_{i=0}^d)$, where $\th_i$
(resp. $\th^*_i$) is the eigenvalue of $A$ (resp. $A^*$) on $V_i$ (resp.
$V^*_i$), and $\{\zeta_i\}_{i=0}^d$ is the split sequence of $A,A^*$
corresponding to $\{\th_i\}_{i=0}^d$ and $\{\th^*_i\}_{i=0}^d$.


title:
Tunneling conductance of a metal-semiconductor heterostructure with
  Rashba effect

abstract:
  We theoretically studied the in-plane tunneling spectroscopy of the hybrid
structure composed of a metal and a semiconductor with Rashba spin-orbit
coupling. We found that the energy spacing between two distinct features in the
conductance spectrum can be used to measure the Rashba energy of the
semiconductor. We also considered the effect that varying the probability of
spin-conserving and spin-flip scattering at the interface has on the overall
conductance. Surprisingly, an increase in interface scattering probability can
actually result in increased conductance under certain conditions.
Particularly, in the tunneling regime, an increase in spin-flip scattering
probability enhances the conductance. It is also found that the interfacial
scattering greatly affects the spin polarization of the conductance in metal,
but hardly affects that in the semiconductor.


title: Model dynamics on a multigrid across multiple length and time scales

abstract:
  Most methods for modelling dynamics posit just two time scales: a fast and a
slow scale. But many applications, including many in continuum mechanics,
possess a wide variety of space-time scales; often they possess a continuum of
space-time scales. I discuss an approach to modelling the discretised dynamics
of advection and diffusion with rigorous support for changing the resolved
spatial grid scale by just a factor of two. The mapping of dynamics from a
finer grid to a coarser grid is then iterated to generate a hierarchy of models
across a wide range of space-time scales, all with rigorous support across the
whole hierarchy. This approach empowers us with great flexibility in modelling
complex dynamics over multiple scales.


title:
An efficient methodology for modeling complex computer codes with
  Gaussian processes

abstract:
  Complex computer codes are often too time expensive to be directly used to
perform uncertainty propagation studies, global sensitivity analysis or to
solve optimization problems. A well known and widely used method to circumvent
this inconvenience consists in replacing the complex computer code by a reduced
model, called a metamodel, or a response surface that represents the computer
code and requires acceptable calculation time. One particular class of
metamodels is studied: the Gaussian process model that is characterized by its
mean and covariance functions. A specific estimation procedure is developed to
adjust a Gaussian process model in complex cases (non linear relations, highly
dispersed or discontinuous output, high dimensional input, inadequate sampling
designs, ...). The efficiency of this algorithm is compared to the efficiency
of other existing algorithms on an analytical test case. The proposed
methodology is also illustrated for the case of a complex hydrogeological
computer code, simulating radionuclide transport in groundwater.


title: On doubly stochastic quadratic operators and Birkhoff's problem

abstract:
  In the present paper we introduce a concept of doubly stochastic quadratic
operator. We prove necessary and sufficient conditions for doubly stochasticity
of operator. Besides, we prove that the set of all doubly stochastic operators
forms convex polytope. Finally, we study analogue of Birkhoff's theorem for the
class of doubly stochastic quadratic operators.


title: Ising Problem on Simple Cubic Lattice

abstract:
  Simple cubic lattice (SC lattice) can be viewed as plane triangular lattice
(PT lattice) by viewing it along its principle diagonal lines. By viewing thus
we establish the exact one-to-one correspondence between the closed graphs on
SC lattice and the corresponding closed graphs on PT lattice. We thus see that
the propagator for PT lattice (with suitable modifications) can be used to
solve, at least in principle, the 3D Ising problem for SC lattice in the
absence of external magnetic field. A new method is then proposed to generate
high temperature expansion for the partition function. This method is
applicable to 2D as well as 3D lattices. This method does not require explicit
counting of closed graphs and this counting is achieved in an indirect way and
thus exact series expansion can be achieved up to any sufficiently large order.


title: Metastability and magnetic memory effect in Ni-Mn-Sn alloy

abstract:
  Magneto-structural instability in the ferromagnetic shape memory alloy of
composition Ni$_2$Mn$_{1.4}$Sn$_{0.6}$ is investigated by transport and
magnetic measurements. Large negative magnetoresistance is observed around the
martensitic transition temperature (90-210 K). Both magnetization and
magnetoresistance data indicate that upon the application of an external
magnetic field at a constant temperature, the sample attains a field-induced
arrested state which persists even when the field is withdrawn. We observe an
intriguing behavior of the arrested state that it can remember the last highest
field it has experienced. The field-induced structural transition plays the key
role for the observed anomaly and the observed irreversibility can be accounted
by the Landau-type free energy model for the first order phase transition.


title:
Testing polynomial covariate effects in linear and generalized linear
  mixed models

abstract:
  An important feature of linear mixed models and generalized linear mixed
models is that the conditional mean of the response given the random effects,
after transformed by a link function, is linearly related to the fixed
covariate effects and random effects. Therefore, it is of practical importance
to test the adequacy of this assumption, particularly the assumption of linear
covariate effects. In this paper, we review procedures that can be used for
testing polynomial covariate effects in these popular models. Specifically,
four types of hypothesis testing approaches are reviewed, i.e. R tests,
likelihood ratio tests, score tests and residual-based tests. Derivation and
performance of each testing procedure will be discussed, including a small
simulation study for comparing the likelihood ratio tests with the score tests.