title:
Poisson and Diffusion Approximation of Stochastic Schrodinger equations
  with Control

abstract:
  "Quantum trajectories" are solutions of stochastic differential equations of
non-usual type. Such equations are called "Belavkin" or "Stochastic
Schr\"odinger Equations" and describe random phenomena in continuous
measurement theory of Open Quantum System. Many recent investigations deal with
the control theory in such model. In this article, stochastic models are
mathematically and physically justified as limit of concrete discrete
procedures called "Quantum Repeated Measurements". In particular, this gives a
rigorous justification of the Poisson and diffusion approximation in quantum
measurement theory with control. Furthermore we investigate some examples using
control in quantum mechanics.


title:
The Most Severe Test for Hydrophobicity Scales: Two Proteins with 88%
  Sequence Identity but Different Structure and Function

abstract:
  Protein-protein interactions (protein functionalities) are mediated by water,
which compacts individual proteins and promotes close and temporarily stable
large-area protein-protein interfaces. In their classic paper Kyte and
Doolittle (KD) concluded that the "simplicity and graphic nature of
hydrophobicity scales make them very useful tools for the evaluation of protein
structures". In practice, however, attempts to develop hydrophobicity scales
(for example, compatible with classical force fields (CFF) in calculating the
energetics of protein folding) have encountered many difficulties. Here we
suggest an entirely different approach, based on the idea that proteins are
self-organized networks, subject to finite-scale criticality (like some network
glasses). We test this proposal against two small proteins that are delicately
balanced between alpha and alpha/beta structures, with different functions
encoded with only 12% of their amino acids. This example explains why protein
structure prediction is so challenging, and it provides a severe test for the
accuracy and content of hydrophobicity scales. The new method confirms KD's
evaluation, and at the same time suggests that protein structure, dynamics and
function can be best discussed without using CFF.


title: Quantum Boundaries in Minkowski Space

abstract:
  It is claimed in another paper that the collapse of a quantum mechanical wave
function is more than invariant, it is trans-representational. It must occur
along a fully invariant surface. The obvious surface available for this purpose
is that of the backward time cone of the collapse event as proposed by Hellwig
and Kraus. This collapse is widely believed to result in paradoxical causal
loops that cannot be removed by special relativistic or standard quantum
mechanical considerations alone. However, the paradox is resolved when we apply
the qRule foundation theory that is developed in the other paper. The causal
and temporal orders of state reduction are then found to be in agreement with
one another, and the resulting boundaries in Minkowski space are shown to have
a novel architecture that limits the range of a Hellwig-Kraus reduction in
space and time. Although these boundaries have been worked out using the
qRules, they should be the same for any foundation theory that treats the
collapse of a wave in an invariant way, and requires that a collapse destroys
the possibility of any further influence on itself, as do the qRules.
  Keywords: measurement, state reduction, wave collapse.


title:
SDSS J142625.71+575218.3, a Prototype for a New Class of Variable White
  Dwarf

abstract:
  We present the results of a search for pulsations in six of the recently
discovered carbon-atmosphere white dwarf ("hot DQ") stars. Based on our
theoretical calculations, the star SDSS J142625.71+575218.3 is the only object
expected to pulsate. We observe this star to be variable, with significant
power at 417.7 s and 208.8 s (first harmonic), making it a strong candidate as
the first member of a new class of pulsating white dwarf stars, the DQVs. Its
folded pulse shape, however, is quite different from that of other white dwarf
variables, and shows similarities with that of the cataclysmic variable AM CVn,
raising the possibility that this star may be a carbon-transferring analog of
AM CVn stars. In either case, these observations represent the discovery of a
new and exciting class of object.


title: Aubry sets vs Mather sets in two degrees of freedom

abstract:
  We study autonomous Tonelli Lagrangians on closed surfaces. We aim to clarify
the relationship between the Aubry set and the Mather set, when the latter
consists of periodic orbits which are not fixed points. Our main result says
that in that case the Aubry set and the Mather set almost always coincide.


title:
Asymptotic behavior and hypercontractivity in nonautonomous
  Ornstein-Uhlenbeck equations

abstract:
  In this paper we investigate a class of nonautonomous linear parabolic
problems with time depending Ornstein-Uhlenbeck operators. We study the
asymptotic behavior of the associated evolution operator and evolution
semigroup in the periodic and non-periodic situation. Moreover, we show that
the associated evolution operator is hypercontractive.


title:
Transverse oscillations of flowing prominence threads observed with
  Hinode

abstract:
  Recent observations with the Hinode Solar Optical Telescope display an active
region prominence whose fine threads oscillate in the vertical direction as
they move along a path parallel to the photosphere. A seismological analysis of
this event is carried out by taking advantage of the small radius of these
structures compared to the total length of magnetic field lines, i.e. by using
the thin tube approximation. This analysis reveals that the oscillatory period
is only slightly modified by the existence of the flow and that the difference
between the period of a flowing thread and a static one is below the error bars
of these observations. Moreover, although it is not possible to obtain values
of the physical parameters, a lower bound for the Alfv\'en speed (ranging
between 120 km s$^{-1}$ and 350 km s$^{-1}$) is obtained for each of the
threads. Such Alfv\'en speeds agree with the intense magnetic fields and large
densities usually found in active region prominences.


title: New observations of cool carbon stars in the halo

abstract:
  We report new results of our search for rare, cool carbon stars located at
large distances from the galactic plane. Eighteen new C stars were discovered.
Six are remarkable by showing the two peculiarities of a strong infrared excess
at 12 microns and a large height above the Galactic plane, from 1.7 to 6 kpc.
The number of C stars with these properties has been increased to 16. Mass-loss
rates were tentatively estimated by assuming that all these 16 stars are Miras
and by using the correlation between Mdot and the K-12 colour index. It is
found that several stars have large mass loss, with median Mdot around 4E-06
solar mass per year. It would be desirable to detect their CO emission ...
Eight stars might be at more than 30 kpc from the Sun, and two at the
unprecedented distance of 150 kpc (this abstract has been abridged).


title: An analytical description for the cosmological constant

abstract:
  From the principles of quantum cosmologies we can justify the reason for an
inverse-square law for the cosmological constant with no conflict with
observations. Although this general expression for $\Lambda$ is well known in
the literature, in this work we introduce some analytical solutions for the
scale factor different from the literature. The underlying motivation to carry
out these solutions is the fact that the time variation of $\Lambda$ can lead
to a creation of matter and/or radiation such as to help in the investigation
of the age of the Universe. The knowledge of the scale factor behavior might
shed some light on these questions since the entire evolution of a homogeneous
isotropic Universe is contained in the scale factor.


title: Boundary monomers in the dimer model

abstract:
  The correlation functions of an arbitrary number of boundary monomers in the
system of close-packed dimers on the square lattice are computed exactly in the
scaling limit. The equivalence of the 2n-point correlation functions with those
of a complex free fermion is proved, thereby reinforcing the description of the
monomer-dimer model by a conformal free field theory with central charge c=1.

categories: cond-mat.stat-mech hep-th math-ph math.MP


title: Optical evolution of Nova Ophiuchi 2007 = V2615 Oph

abstract:
  The moderately fast Nova Oph 2007 reached maximum brightness on March 28,
2007 at V=8.52, B-V=+1.12, V-Rc=+0.76, V-Ic=+1.59 and Rc-Ic=+0.83, after fast
initial rise and a pre-maximum halt lasting a week. Decline times were
t(V,2)=26.5, t(B,2)=30, t(V,3)=48.5 and t(B,3)=56.5 days. The distance to the
nova is d=3.7 kpc, the height above the galactic plane z=215 pc, the reddening
E(B-V)=0.90 and the absolute magnitude at maximum M(V,max)=-7.2 and
M(B,max)=-7.0. The spectrum four days before maximum resembled a F6
super-giant, in agreement with broad-band colors. It later developed into that
of a standard 'FeII'-class nova. Nine days past maximum, the expansion velocity
estimated from the width of H$\alpha$ emission component was 730 km/s, and the
displacement from it of the principal and diffuse enhanced absorption systems
were 650 and 1380 km/s, respectively. Dust probably formed and disappeared
during the period from 82 to 100 days past maximum, causing (at peak dust
concentration) an extinction of Delta B=1.8 mag and an extra Delta E(B-V)=0.44
reddening.


title:
Existence, uniqueness and stability of equilibrium states for
  non-uniformly expanding maps

abstract:
  We prove existence of finitely many ergodic equilibrium states for a large
class of non-uniformly expanding local homeomorphisms on compact manifolds and
Holder continuous potentials with not very large oscillation. No Markov
structure is assumed. If the transformation is topologically mixing there is a
unique equilibrium state, it is exact and satisfies a non-uniform Gibbs
property. Under mild additional assumptions we also prove that the equilibrium
states vary continuously with the dynamics and the potentials (statistical
stability) and are also stable under stochastic perturbations of the
transformation.


title: Entanglement in a periodic quench

abstract:
  We consider a chain of free electrons with periodically switched dimerization
and study the entanglement entropy of a segment with the remainder of the
system. We show that it evolves in a stepwise manner towards a value
proportional to the length of the segment and displays in general slow
oscillations. For particular quench periods and full dimerization an explicit
solution is given. Relations to equilibrium lattice models are pointed out.


title: A New Central Limit Theorem under Sublinear Expectations

abstract:
  We describe a new framework of a sublinear expectation space and the related
notions and results of distributions, independence. A new notion of
G-distributions is introduced which generalizes our G-normal-distribution in
the sense that mean-uncertainty can be also described. W present our new result
of central limit theorem under sublinear expectation. This theorem can be also
regarded as a generalization of the law of large number in the case of
mean-uncertainty.


title: The WASA Detector Facility at CELSIUS

abstract:
  The WASA 4pi multidetector system, aimed at investigating light meson
production in light ion collisions and eta meson rare decays at the CELSIUS
storage ring in Uppsala is presented. A detailed description of the design,
together with the anticipated and achieved performance parameters are given.


title:
One-loop divergences in the two-dimensional non-anticommutative
  supersymmetric sigma-model

abstract:
  We discuss the structure of the non-anticommutative N=2 non-linear
sigma-model in two dimensions, constructing differential operators which
implement the deformed supersymmetry generators and using them to reproduce the
classical action. We then compute the one-loop quantum corrections and express
them in a more compact form using the differential operators.


title:
Covariant particle exchange for kappa-deformed theories in 1+1
  dimensions

abstract:
  We consider the exchange of identical scalar particles in theories with
kappa-deformed Poincare symmetry. We argue that, at least in 1+1 dimensions,
the symmetric group S_N can be realized on the space of N-particle states in a
kappa-covariant fashion. For the case of two particles this realization is
unique: we show that there is only one non-trivial intertwiner, which
automatically squares to the identity.


title: Magnetic Graphene Nanohole Superlattices

abstract:
  We investigate the magnetic properties of nano-holes (NHs) patterned in
graphene using first principles calculations. We show that superlattices
consisting of a periodic array of NHs form a new family of 2D crystalline
"bulk" magnets whose collective magnetic behavior is governed by inter-NH
spin-spin interaction. They exhibit long-range magnetic order well above room
temperature. Furthermore, magnetic semiconductors can be made by doping
magnetic NHs into semiconducting NH superlattices. Our findings offer a new
material system for fundamental studies of spin-spin interaction and magnetic
ordering in low dimensions, and open up the exciting opportunities of making
engineered magnetic materials for storage media and spintronics applications.


title: Partially Strong WW Scattering

abstract:
  What if only a light Higgs boson is discovered at the CERN LHC?
  Conventional wisdom tells us that the scattering of longitudinal weak gauge
bosons would not grow strong at high energies. We show that this is not always
true. In some composite models, two-Higgs-doublet models, or even
supersymmetric models, the presence of a light Higgs boson does not guarantee
the complete unitarization of the $WW$ scattering. After the partial
unitarization by the light Higgs boson, the $WW$ scattering becomes strongly
interacting until it hits one or more heavier Higgs bosons or other strong
dynamics. We analyze how the LHC experiments can reveal this interesting
possibility of partially strong $WW$ scattering.


title: On the cohomology of Young modules for the symmetric group

abstract:
  The main result of this paper is an application of the topology of the space
$Q(X)$ to obtain results for the cohomology of the symmetric group on $d$
letters, $\Sigma_d$, with `twisted' coefficients in various choices of Young
modules and to show that these computations reduce to certain natural questions
in representation theory. The authors extend classical methods for analyzing
the homology of certain spaces $Q(X)$ with mod-$p$ coefficients to describe the
homology $\HH_{\bullet}(\Sigma_d, V^{\otimes d})$ as a module for the general
linear group $GL(V)$ over an algebraically closed field $k$ of characteristic
$p$. As a direct application, these results provide a method of reducing the
computation of $\text{Ext}^{\bullet}_{\Sigma_{d}}(Y^{\lambda},Y^{\mu})$ (where
$Y^{\lambda}$, $Y^{\mu}$ are Young modules) to a representation theoretic
problem involving the determination of tensor products and decomposition
numbers. In particular, in characteristic two, for many $d$, a complete
determination of $\Hs Y^\lambda)$ can be found. This is the first nontrivial
class of symmetric group modules where a complete description of the cohomology
in all degrees can be given. For arbitrary $d$ the authors determine
$\HH^i(\Sigma_d,Y^\lambda)$ for $i=0,1,2$. An interesting phenomenon is
uncovered--namely a stability result reminiscent of generic cohomology for
algebraic groups. For each $i$ the cohomology $\HH^i(\Sigma_{p^ad},
Y^{p^a\lambda})$ stabilizes as $a$ increases. The methods in this paper are
also powerful enough to determine, for any $p$ and $\lambda$, precisely when
$\HH^{\bullet}(\sd,Y^\lambda)=0$. Such modules with vanishing cohomology are of
great interest in representation theory because their support varieties
constitute the representation theoretic nucleus.


title: Massive molecular outflows associated with UCHII/HII regions

abstract:
  Aims: We searched for the molecular outflows from fifteen molecular clouds
associated with ultra-compact and compact HII (UCHII/HII) regions and discussed
possible gas heating mechanism. Methods: Mapping observations of CO $J=3-2$ and
$J=2-1$ lines were carried out with the KOSMA 3m-Telescope towards the 15 HII
regions/molecular cloud complexes. Results: Ten molecular outflows were
identified out of the fifteen HII region/molecular cloud complexes. The higher
outflow detection rate (67%) suggested that such outflows are as common in high
mass star forming regions as those in low mass star forming regions, which is
consistent with the results of other authors. The observations also showed that
the outflow might occur in the HII region. The integrated CO line intensity
ratios (${\rm R_{I_{CO(3-2)}/I_{CO(2-1)}}}$) were determined from the core
component of the spectra as well as from both the blue and red wings. Maximum
line intensity ratios from the wings and core components appeared to be related
to the mid-infrared sources imaged by Midcourse Space Experiment (MSX). The
relationship between the maximum line intensity ratios and MSX sources
indicates that the molecular gas could be heated by the emission of dust
associated with massive stars. Based on maser observations reported in the
literature, we found that ${\rm H_{2}O}$ masers were only detected in seven
regions. The ${\rm H_{2}O}$ masers in these regions are located near the MSX
sources and within the maximum line intensity ratio regions, suggesting that
${\rm H_{2}O}$ masers occur in relatively warm environments.


title: Inflation with Non-Minimal Coupling: Metric vs. Palatini Formulations

abstract:
  We analyze non-minimally coupled scalar field theories in metric
(second-order) and Palatini (first-order) formalisms in a comparative fashion.
After contrasting them in a general setup, we specialize to inflation and find
that the two formalisms differ in their predictions for various cosmological
parameters. The main reason is that dependencies on the non-minimal coupling
parameter are different in the two formalisms. For successful inflation, the
Palatini approach prefers a much larger value for the non-minimal coupling
parameter than the Metric approach. Unlike the Metric formalism, in Palatini,
the inflaton stays well below the Planck scale whereby providing a natural
inflationary epoch.


title: Boundary chromatic polynomial

abstract:
  We consider proper colorings of planar graphs embedded in the annulus, such
that vertices on one rim can take Q_s colors, while all remaining vertices can
take Q colors. The corresponding chromatic polynomial is related to the
partition function of a boundary loop model. Using results for the latter, the
phase diagram of the coloring problem (with real Q and Q_s) is inferred, in the
limits of two-dimensional or quasi one-dimensional infinite graphs. We find in
particular that the special role played by Beraha numbers Q=4 cos^2(pi/n) for
the usual chromatic polynomial does not extend to the case Q different from
Q_s. The agreement with (scarce) existing numerical results is perfect; further
numerical checks are presented here.


title: Theory of cavity-assisted microwave cooling of polar molecules

abstract:
  We analyze cavity-assisted cooling schemes for polar molecules in the
microwave domain, where molecules are excited on a rotational transition and
energy is dissipated via strong interactions with a lossy stripline cavity, as
recently proposed by A. Andre et al., Nature Physics 2, 636 (2006). We identify
the dominant cooling and heating mechanisms in this setup and study cooling
rates and final temperatures in various parameter regimes. In particular we
analyze the effects of a finite environment temperature on the cooling
efficiency, and find minimal temperature and optimized cooling rate in the
strong drive regime. Further we discuss the trade-off between efficiency of
cavity cooling and robustness with respect to ubiquitous imperfections in a
realistic experimental setup, such as anharmonicity of the trapping potential.


title:
Geometry of Vlasov kinetic moments: a bosonic Fock space for the
  symmetric Schouten bracket

abstract:
  The dynamics of Vlasov kinetic moments is shown to be Lie-Poisson on the dual
Lie algebra of symmetric contravariant tensor fields. The corresponding Lie
bracket is identified with the symmetric Schouten bracket and the moment Lie
algebra is related with a bundle of bosonic Fock spaces, where creation and
annihilation operators are used to construct the cold plasma closure. Kinetic
moments are also shown to define a momentum map, which is infinitesimally
equivariant. This momentum map is the dual of a Lie algebra homomorphism,
defined through the Schouten bracket. Finally the moment Lie-Poisson bracket is
extended to anisotropic interactions.

categories: nlin.CD math-ph math.MP physics.plasm-ph


title: Geometry of the Standard Model

abstract:
  This is a brief description of the classical part of the Standard Model of
particles and interactions, using the language of vector bundles over the
spacetime and operations on them.


title: Diffusion Processes in Phase Spaces and Quantum Mechanics

abstract:
  A diffusion process for charge distributions in a phase space is examined.
The corresponding charge moves in a force field and under an action of a random
field. There are the diffusion motions for coordinates and for momenta. In our
model, an inner state of the charge is defined by a complex vector. The vector
rotates with a great constant angular velocity with respect to the proper time
of the charge. A state of the diffusion process is a (complex-valued) wave
function on the phase space. As in quantum mechanics, we assume that, for the
wave functions, the superposition principle holds. The diffusion process
averages out vectors of inner states from different points of the phase space.
A differential equation for this diffusion process is founded and examined. We
demonstrate that the motion (described by this process) decomposes into a fast
motion and a slow motion. The fast motion reduces an arbitrary wave function to
a function from a subspace whose elements are parameterized by complex-valued
functions of coordinates. The slow motion occurs in this subspace and it is
described by the Schr\''odinger equation. The parameters of the suggested model
are estimated. The duration of the fast motion is of order $10^{-11}$ s.


title: Quantum mechanics on curved 2D systems with electric and magnetic fields

abstract:
  We derive the Schroedinger equation for a spinless charged particle
constrained to a curved surface with electric and magnetics fields applied. The
particle is confined on the surface using a thin-layer procedure, giving rise
to the well-known geometric potential. The electric and magnetic fields are
included via the four-potential. We find that there is no coupling between the
fields and the surface curvature and that, with a proper choice of the gauge,
the surface and transverse dynamics are exactly separable. Finally, the
Hamiltonian for the cylinder, sphere and torus are analytically derived.


title: Non-isolated dynamic black holes and white holes

abstract:
  Modifying the Kerr-Schild transformation used to generate black and white
hole spacetimes, new dynamic black and white holes are obtained using a
time-dependent Kerr-Schild scalar field. Physical solutions are found for black
holes that shrink with time and for white holes that expand with time. The
black hole spacetimes are physical only in the vicinity of the black hole, with
the physical region increasing in radius with time. The white hole spacetimes
are physical throughout. Unlike the standard Schwarzschild solution the
singularities are non-isolated, since the time-dependence introduces a
mass-energy distribution. The surfaces in the metrics where g_{tt}=g^{rr}=0 are
dynamic, moving inward with time for the black holes and outward for the white
holes, which leads to a question of whether these spacetimes truly have event
horizons--a problem shared with Vaidya's cosmological black hole spacetimes. By
finding a surface that shrinks or expands at the same rate as the null
geodesics move, and within which null geodesics move inward or outward faster
than the surfaces shrink or expand respectively, it is verified that these do
in fact behave like black and white holes.


title: Efficient output coupling of intracavity high harmonic generation

abstract:
  We demonstrate a novel technique for coupling XUV harmonic radiation out of a
femtosecond enhancement cavity. We use a small-period diffraction grating
etched directly into the surface of a dielectric mirror. For the fundamental
light, this element acts as a high reflector. For harmonic wavelengths, it acts
as a diffraction grating, coupling XUV radiation out of the cavity. Using this
method, we observed the 3rd through 21st odd harmonics with a dramatic increase
in usable power over previous results of high harmonic generation at high
repetition rates.


title:
Multimeson production in pp interactions as a background for eta and
  eta' decays

abstract:
  Multimeson production in pp interactions comprises important background for
eta, omega and eta' mesons production experiments and for the studies of their
decays planned with WASA detector at COSY. The available information about the
reactions is summarized and the need for efforts to describe the processes is
stressed.


title: Thermal and quantum superstring cosmologies

abstract:
  We consider four dimensional heterotic string backgrounds for which
supersymmetry is spontaneously broken via the Scherk-Schwarz mechanism on an
internal spatial cycle and by finite temperature effects. We concentrate on
initially flat backgrounds with N=4 and N=2 amount of supersymmetry. Thermal
and quantum corrections give rise to a non-trivial cosmological evolution. We
show that these corrections are under control and calculable due to the
underlying no-scale structure of the effective supergravity theory. The
effective Friedmann-Hubble equation involves a radiation term ~1/a^4 and a
curvature term ~1/a^2, whose coefficients are functions of ratio of the
gravitino mass scale to the temperature.


title: Digital Ecosystems: Self-Organisation of Evolving Agent Populations

abstract:
  A primary motivation for our research in Digital Ecosystems is the desire to
exploit the self-organising properties of biological ecosystems. Ecosystems are
thought to be robust, scalable architectures that can automatically solve
complex, dynamic problems. Self-organisation is perhaps one of the most
desirable features in the systems that we engineer, and it is important for us
to be able to measure self-organising behaviour. We investigate the
self-organising aspects of Digital Ecosystems, created through the application
of evolutionary computing to Multi-Agent Systems (MASs), aiming to determine a
macroscopic variable to characterise the self-organisation of the evolving
agent populations within. We study a measure for the self-organisation called
Physical Complexity; based on statistical physics, automata theory, and
information theory, providing a measure of information relative to the
randomness in an organism's genome, by calculating the entropy in a population.
We investigate an extension to include populations of variable length, and then
built upon this to construct an efficiency measure to investigate clustering
within evolving agent populations. Overall an insight has been achieved into
where and how self-organisation occurs in our Digital Ecosystem, and how it can
be quantified.


title: Conversion of charge input into Kondo response

abstract:
  We show how the charge input signal applied to the gate electrode in double
quantum dot may be converted to a pulse in the Kondo cotunneling current as a
spin response of a nano-device in a strong Coulomb blockade regime. The
stochastic component of the input signal comes as the infrared cutoff of Kondo
transmission.


title: $SQED_4$ and $QED_4$ on the null-plane

abstract:
  We studied the scalar electrodynamics ($SQED_{4}$) and the spinor
electrodynamics ($QED_{4}$) in the null-plane formalism. We followed the
Dirac's technique for constrained systems to perform a detailed analysis of the
constraint structure in both theories. We imposed the appropriated boundary
conditions on the fields to fix the hidden subset first class constraints which
generate improper gauge transformations and obtain an unique inverse of the
second class constraint matrix. Finally, choosing the null-plane gauge
condition, we determined the generalized Dirac brackets of the independent
dynamical variables which via the correspondence principle give the
(anti)-commutators for posterior quantization.


title:
Spreading of EGF Receptor Activity into EGF-free Regions and Molecular
  Therapies of Cancer

abstract:
  The primary activation of the epidermal growth factor receptor (EGFR) has
become a prominent target for molecular therapies against several forms of
cancer. But despite considerable progress during the last years, many of its
aspects remain poorly understood. Experiments on lateral spreading of receptor
activity into ligand-free regions challenge the current standard models of EGFR
activation. Here, we propose and study a theoretical model, which explains
spreading into ligand-free regions without introducing any new, unknown kinetic
parameters. The model exhibits bistability of activity, induced by a generic
reaction mechanism, which consists of activation via dimerization and
deactivation via a Michaelis-Menten reaction. It possesses slow propagating
front solutions and faster initial transients. We analyze relevant experiments
and find that they are in quantitative accordance with the fast initial modes
of spreading, but not with the slow propagating front. We point out that
lateral spreading of activity is linked to pathological levels of persistent
receptor activity as observed in cancer cells and exemplify uses of this link
for the design and quick evaluation of molecular therapies targeting primary
activation of EGFR.


title: Statistical aspects of birth--and--growth stochastic processes

abstract:
  The paper considers a particular family of set--valued stochastic processes
modeling birth--and--growth processes. The proposed setting allows us to
investigate the nucleation and the growth processes. A decomposition theorem is
established to characterize the nucleation and the growth. As a consequence,
different consistent set--valued estimators are studied for growth process.
Moreover, the nucleation process is studied via the hitting function, and a
consistent estimator of the nucleation hitting function is derived.


title: An absorption origin for the X-ray spectral variability of MCG-6-30-15

abstract:
  The Seyfert I galaxy MCG-6-30-15 shows one of the best examples of a broad
"red wing" of emission in its X-ray spectrum at energies 2 < E < 6.4 keV,
commonly interpreted as being caused by relativistically-blurred reflection
close to the event horizon of the black hole. We aim to test an alternative
model in which absorption creates the observed spectral shape, explains the
puzzling lack of variability of the red wing and reduces the high reflection
albedo, substantially greater than unity, that is otherwise inferred at
energies E > 20 keV. We compiled all the available long-exposure, high-quality
data for MCG-6-30-15: 522 ks of Chandra HETGS, 282 ks of XMM-Newton pn/RGS and
253 ks of Suzaku XIS/PIN data. This is the first analysis of this full dataset.
We investigated the spectral variability on timescales >20 ks using principal
components analysis and fitted spectral models to "flux state" and mean spectra
over the energy range 0.5-45 keV (depending on detector). The absorber model
was based on the zones previously identified in the high-resolution grating
data. Joint fits were carried out to any data that were simultaneous. Multiple
absorbing zones covering a wide range of ionisation are required by the grating
data, including a highly ionised outflowing zone. A variable partial-covering
zone plus absorbed low-ionisation reflection, distant from the source, provides
a complete description of the variable X-ray spectrum. A single model fits all
the data. We conclude that these zones are responsible for the red wing, its
apparent lack of variability, the absorption structure around the Fe K-alpha
line, the soft-band "excess" and the high flux seen in the hard X-ray band. A
relativistically-blurred Fe line is not required in this model. We suggest the
partial covering zone is a clumpy wind from the accretion disk.


title: On a worldsheet dual of the Gaussian matrix model

abstract:
  We discuss a modification of Gopakumar's prescription for constructing string
theory duals of free gauge theories. We use this prescription to construct an
unconventional worldsheet dual of the Gaussian matrix model.


title:
On (alpha,beta,gamma)-derivations of Lie algebras and corresponding
  invariant functions

abstract:
  We consider finite-dimensional complex Lie algebras. We generalize the
concept of Lie derivations via certain complex parameters and obtain various
Lie and Jordan operator algebras as well as two one-parametric sets of linear
operators. Using these parametric sets, we introduce complex functions with
fundamental property - invariance under Lie isomorphisms. One of these
basis-independent functions represents a complete set of invariant(s) for
three-dimensional Lie algebras. We present also its application on physically
motivated examples in dimension eight.


title:
Supersymmetric codimension-two branes and U(1)_R mediation in 6D gauged
  supergravity

abstract:
  We construct a consistent supersymmetric action for brane chiral and vector
multiplets in a six-dimensional chiral gauged supergravity. A nonzero brane
tension can be accommodated by allowing for a brane-localized Fayet-Iliopoulos
term proportional to the brane tension. When the brane chiral multiplet is
charged under the bulk U(1)_R, we obtain a nontrivial coupling to the extra
component of the U(1)_R gauge field strength as well as a singular scalar
self-interaction term. Dimensionally reducing to 4D on a football
supersymmetric solution, we discuss the implication of such interactions for
obtaining the U(1)_R D-term in the 4D effective supergravity. By assuming the
bulk gaugino condensates and nonzero brane F- and/or D-term for the uplifting
potential, we have all the moduli stabilized with a vanishing cosmological
constant. The brane scalar with nonzero R charge then gets a soft mass of order
the gravitino mass. The overall sign of the soft mass squared depends on the
sign of the R charge as well as whether the brane F- or D-term dominates.


title: Lev Landau and the problem of singularities in cosmology

abstract:
  We consider different aspects of the problem of cosmological singularity such
as the BKL oscillatory approach to singularity, the new features of the
cosmological dynamics in the neighbourhood of the singularity in
multidimensional and superstring cosmological models and their connections with
such a modern branch of mathematics as infinite-dimensional Lie algebras.
Besides, we consider some new types of cosmological singularities which were
widely discussed during last decade after the discovery of the phenomenon of
cosmic acceleration.


title:
Properties of the Reissner-Nordstr\"om Spacetimes with a Nonzero
  Cosmological Constant

abstract:
  Properties of the Reissner-Nordstr\"om black-hole and naked-singularity
spacetimes with a nonzero cosmological constant are represented by their
geodetical structure and embedding diagrams of the central planes of both the
ordinary geometry and associated optical reference geometry. Motion of test
particles and photons is described in terms of an appropriate `effective
potential.' Circular geodesics are discussed and photon escape cones are
determined. In all asymptotically anti-dS black-hole spacetimes and some
asymptotically dS black-hole spacetimes a region containing stable circular
geodesics exists, which allows accretion processes in the disk regime. The
inner region is limited from below by particles with zero angular momentum that
are located in stable equilibrium positions. The inertial and gravitational
forces related to the optical reference geometry are introduced and specified
for the circular motion. It is shown how the properties of the centrifugal
force are closely related to the properties of the optical reference geometry
embedding diagrams.


title:
Simulation of Many-Body Hamiltonians using Perturbation Theory with
  Bounded-Strength Interactions

abstract:
  We show how to map a given n-qubit target Hamiltonian with bounded-strength
k-body interactions onto a simulator Hamiltonian with two-body interactions,
such that the ground-state energy of the target and the simulator Hamiltonians
are the same up to an extensive error O(epsilon n) for arbitrary small epsilon.
The strength of interactions in the simulator Hamiltonian depends on epsilon
and k but does not depend on n. We accomplish this reduction using a new way of
deriving an effective low-energy Hamiltonian which relies on the
Schrieffer-Wolff transformation of many-body physics.


title:
Role of the transverse field in inverse freezing in the fermionic Ising
  spin-glass model

abstract:
  We investigate the inverse freezing in the fermionic Ising spin-glass (FISG)
model in a transverse field $\Gamma$. The grand canonical potential is
calculated in the static approximation, replica symmetry and one-step replica
symmetry breaking Parisi scheme. It is argued that the average occupation per
site $n$ is strongly affected by $\Gamma$. As consequence, the boundary phase
is modified and, therefore, the reentrance associated with the inverse freezing
is modified too.


title: Adsorption Kinetics of a Single Polymer on a Solid Plane

abstract:
  We study analytically and by means of an off-lattice bead-spring dynamic
Monte Carlo simulation model the adsorption kinetics of a single macromolecule
on a structureless flat substrate in the regime of strong physisorption. The
underlying notion of a ``stem-flower'' polymer conformation, and the related
mechanism of ``zipping'' during the adsorption process are shown to lead to a
Fokker-Planck equation with reflecting boundary conditions for the
time-dependent probability distribution function (PDF) of the number of
adsorbed monomers. The theoretical treatment predicts that the mean fraction of
adsorbed segments grows with time as a power law with a power of $(1+\nu)^{-1}$
where $\nu\approx 3/5$ is the Flory exponent. The instantaneous distribution of
train lengths is predicted to follow an exponential relationship. The
corresponding PDFs for loops and tails are also derived. The complete solution
for the time-dependent PDF of the number of adsorbed monomers is obtained
numerically from the set of discrete coupled differential equations and shown
to be in perfect agreement with the Monte Carlo simulation results. In addition
to homopolymer adsorption, we study also regular multiblock copolymers and
random copolymers, and demonstrate that their adsorption kinetics may be
considered within the same theoretical model.


title:
Structure and dynamics of galaxies with a low surface brightness disc.
  I. The stellar and ionised-gas kinematics

abstract:
  (abridged) Photometry and long-slit spectroscopy are presented for a sample
of 6 galaxies with a low surface brightness stellar disc and a bulge. The
stellar and ionised-gas kinematics were measured along the major and minor axis
in half of the sample galaxies, whereas the other half was observed only along
two diagonal axes. Spectra along two diagonal axes were obtained also for one
of the objects with major and minor axis spectra. The kinematic measurements
extend in the disc region out to a surface-brightness level mu_R~24mag/arcsec^2
reaching in all cases the flat part of the rotation curve. The stellar
kinematics turns out to be more regular and symmetric than the ionised-gas
kinematics, which often shows the presence of non-circular, off-plane, and
non-ordered motions. This raises the question about the reliability of the use
of the ionised gas as the tracer of the circular velocity in the modeling of
the mass distribution, in particular in the central regions of low surface
brightness galaxies.


title:
Cosmic ray primary mass composition above the knee: deduction from
  lateral distribution of electrons

abstract:
  Influence of shower fluctuations on the shape of lateral distribution of
electrons in EAS of fixed size measured by scintillation counters is analyzed
in framework of scaling formalism. Correction factors for the mean square
radius of electrons are calculated for the experimental conditions of KASCADE
array. Possible improvement of the primary mass discrimination by analysis of
lateral distribution of EAS electrons is discussed in detail.


title:
Discovery of two magnetic massive stars in the Orion Nebula Cluster: a
  clue to the origin of neutron star magnetic fields?

abstract:
  The origin of the magnetic fields in neutron stars, and the physical
differences between magnetars and strongly magnetised radio pulsars are still
under vigorous debate. It has been suggested that the properties of the
progenitors of neutron stars (the massive OB stars), such as rotation, magnetic
fields and mass, may play an important role in the outcome of core collapse
leading to type II SNe. Therefore, knowing the magnetic properties of the
progenitor OB stars would be an important asset for constraining models of
stellar evolution leading to the birth of a neutron star. We present here the
beginning of a broad study with the goal of characterising the magnetic
properties of main sequence massive OB stars. We report the detection of two
new massive magnetic stars in the Orion Nebula Cluster: Par 1772 (HD 36982) and
NU Ori (HD 37061), for which the estimated dipole polar strengths, with 1 sigma
error bars, are 1150 (+320,-200) G and 650 (+220,-170) G respectively.


title: Counting all dyons in N =4 string theory

abstract:
  For dyons in heterotic string theory compactified on a six-torus, with
electric charge vector Q and magnetic charge vector P, the positive integer I =
g.c.d.(Q \wedge P) is an invariant of the U-duality group. We propose the
microscopic theory for computing the spectrum of all dyons for all values of I,
generalizing earlier results that exist only for the simplest case of I=1. Our
derivation uses a combination of arguments from duality, 4d-5d lift, and a
careful analysis of fermionic zero modes. The resulting degeneracy agrees with
the black hole degeneracy for large charges and with the degeneracy of
field-theory dyons for small charges. It naturally satisfies several physical
requirements including integrality and duality invariance. As a byproduct, we
also derive the microscopic (0,4) superconformal field theory relevant for
computing the spectrum of five-dimensional Strominger-Vafa black holes in ALE
backgrounds and count the resulting degeneracies.


title: Observational Effects of Anomalous Boundary Layers in Relativistic Jets

abstract:
  Recent theoretical work has pointed out that the transition layer between a
jet an the medium surrounding it may be more complex than previously thought.
Under physically realizable conditions, the transverse profile of the Lorentz
factor in the boundary layer can be non-monotonic, displaying the absolute
maximum where the flow is faster than at the jet spine, followed by an steep
fall off. Likewise, the rest-mass density, reaches an absolute minimum
(coincident with the maximum in Lorentz factor) and then grows until it reaches
the external medium value. Such a behavior is in contrast to the standard
monotonic decline of the Lorentz factor (from a maximum value at the jet
central spine) and the corresponding increase of the rest-mass density (from
the minimum reached at the jet core). We study the emission properties of the
aforementioned anomalous shear layer structures in kiloparsec-scale jets aiming
to show observable differences with respect to conventional monotonic and
smooth boundary layers.


title: Quotients of the Multiplihedron as Categorified Associahedra

abstract:
  We describe a new sequence of polytopes which characterize A_infinity maps
from a topological monoid to an A_infinity space. Therefore each of these
polytopes is a quotient of the corresponding multiplihedron. Later term(s) in
our sequence of polytopes are demonstrated not to be combinatorially equivalent
to the associahedron, as was previously assumed. They are given the new
collective name composihedra. We point out how these polytopes are used to
parameterize compositions in the formulation of the theories of enriched
bicategories and pseudomonoids in a monoidal bicategory. We present a simple
algorithm for determining the extremal points in Euclidean space whose convex
hull is the nth polytope in the sequence of composihedra, that is, the nth
composihedron.


title:
KohonAnts: A Self-Organizing Ant Algorithm for Clustering and Pattern
  Classification

abstract:
  In this paper we introduce a new ant-based method that takes advantage of the
cooperative self-organization of Ant Colony Systems to create a naturally
inspired clustering and pattern recognition method. The approach considers each
data item as an ant, which moves inside a grid changing the cells it goes
through, in a fashion similar to Kohonen's Self-Organizing Maps. The resulting
algorithm is conceptually more simple, takes less free parameters than other
ant-based clustering algorithms, and, after some parameter tuning, yields very
good results on some benchmark problems.


title: Normal Modes in Model Jammed Systems in Three Dimensions

abstract:
  Vibrational spectra and normal modes of mechanically stable particle packings
in three dimensions are analyzed over a range of compressions, from near the
jamming transition, where the packings lose their rigidity, to far above it. At
high frequency, the normal modes are localized at all compressions. At low
frequency, the nature of the modes depends somewhat on compression. At large
compressions, far from the transition, the lowest-frequency normal modes have
some plane-wave character, though less than one would expect for a crystalline
or isotropic solid. At low compressions near the jamming transition, the
lowest-frequency modes are neither plane-wave-like nor localized. We
characterize these differences, highlighting the unusual dispersion behavior
that emerges for marginally jammed solids.


title: The limit shape of large alternating sign matrices

abstract:
  The problem of the limit shape of large alternating sign matrices (ASMs) is
addressed by studying the emptiness formation probability (EFP) in the
domain-wall six-vertex model. Assuming that the limit shape arises in
correspondence to the `condensation' of almost all solutions of the
saddle-point equations for certain multiple integral representation for EFP, a
conjectural expression for the limit shape of large ASMs is derived. The case
of 3-enumerated ASMs is also considered.


title:
Complex patterns of spontaneous initiations and terminations of
  reentrant circulation in a loop of cardiac tissue

abstract:
  A two-component model is developed that consists of a discrete loop of
cardiac cells that circulates action potentials together with a cardiac pacing
mechanism. Physiological properties of cells such as restitutions of
refractoriness and of conduction velocity are given via experimentally measured
functions. The dynamics of circulating pulses and their interactions with the
pacer are regulated by two threshold relations. Patterns of spontaneous
initiations and terminations of reentry (SITR) generated by this system are
studied through numerical simulations and analytical observations. These
patterns can be regular or irregular; causes of irregularities are identified
as the threshold bistability of reentrant circulation (T-bistability) and in
some cases, also phase-resetting interactions with the pacer.


title: A property of dominance of partitions

abstract:
  Given an integer partition $\la=(\la_1, ..., \la_\ell)$ and an integer k,
denote by $\la^{(k)}$ the sequence of length $\ell$ obtained by reordering the
values $|\la_i-k|$ in non-increasing order. If $\la$ dominates $\mu$ and has
the same weight, then $\la^{(k)}$ dominates $\mu^{(k)}$.


title: Opportunity and choice in social networks

abstract:
  Our societies are heterogeneous in many dimensions such as census, education,
religion, ethnic and cultural composition. The links between individuals - e.g.
by friendship, marriage or collaboration - are not evenly distributed, but
rather tend to be concentrated within the same group. This phenomenon, called
`imbreeding homophily', has been related to either (social) preference for
links with own-type individuals (`choice-based' homophily) or to the prevalence
of individuals of her same type in the choice set of an individual
(`opportunity-based' homophily). Choices determine the network of relations we
observe whereas opportunities pertain to the composition of the (unobservable)
social network individuals are embedded in and out of which their network of
relations is drawn. In this view, we propose a method that, in the presence of
multiple data, allows one to distinguish between opportunity and choice based
homophily. The main intuition is that, with unbiased opportunities, the effect
of choice-based homophily gets weaker and weaker as the size of the minority
shrinks, because individuals of the minority rarely meet and have the chance to
establish links together. The occurrence of homophily in the limit of very
small minorities is therefore an indicator of opportunity bias. We test this
idea across the dimensions of race and education on data on US marriages, and
across race on friendships in US schools.


title: Interpretation of the Cosmological Metric

abstract:
  The cosmological Robertson-Walker metric of general relativity is often said
to have the consequences that (1) the recessional velocity $v$ of a galaxy at
proper distance $\ell$ obeys the Hubble law $v=H\ell$, and therefore galaxies
at sufficiently great distance $\ell$ are receding faster than the speed of
light $c$; (2) faster than light recession does not violate special relativity
theory because the latter is not applicable to the cosmological problem, and
because ``space itself is receding'' faster than $c$ at great distance, and it
is velocity relative to local space that is limited by $c$, not the velocity of
distant objects relative to nearby ones; (3) we can see galaxies receding
faster than the speed of light; and (4) the cosmological redshift is not a
Doppler shift, but is due to a stretching of photon wavelength during
propagation in an expanding universe. We present a particular Robertson-Walker
metric (an empty universe metric) for which a coordinate transformation shows
that none of these interpretation necessarily holds. The resulting paradoxes of
interpretation lead to a deeper understanding of the meaning of the
cosmological metric.


title:
Optical and UV Light Curves of the Accretion Disk Corona Source 4U
  1822-371

abstract:
  The eclipsing low-mass X-ray binary 4U is the prototypical accretion disk
corona (ADC) system. We have obtained new time-resolved UV spectrograms of 4U
with the Hubble Space Telescope and new V- and J-band light curves with the
1.3-m SMARTS telescope at CTIO. We present an updated ephemeris for the times
of the optical/UV eclipses. Model light curves do not give acceptable fits to
the UV eclipses unless the models include an optically-thick ADC.


title: Is LaO$_{1-x}$F$_x$FeAs an electron-phonon superconductor ?

abstract:
  In this paper we calculate the electron-phonon coupling of the
newly-discovered superconductor LaO$_{1-x}$F$_x$FeAs from first-principles,
using Density Functional Perturbation Theory. For pure LaOFeAs, the calculated
electron-phonon coupling constant $\lambda=0.21$ and logarithmic-averaged
frequency $\omega_{ln}=206 K$, give a maximum $T_c$ of 0.8 K, using the
standard Migdal-Eliashberg theory.
  For the $F-$doped compounds, we predict even smaller coupling constants, due
to the strong suppression of the electronic Density of States at the Fermi
level. To reproduce the experimental $T_c=26 K$, a 5-6 times larger coupling
constant would be needed.
  Our results indicate that electron-phonon coupling is not sufficient to
explain superconductivity in the newly-discovered LaO$_{1-x}$F$_x$FeAs
superconductor, probably due to the importance of strong correlation effects.


title:
Constraining white-dwarf kicks in globular clusters : III. Cluster
  Heating

abstract:
  Recent observations of white dwarfs in globular clusters indicate that these
stars may get a velocity kick during their time as giants. This velocity kick
could originate naturally if the mass loss while on the asymptotic giant branch
is slightly asymmetric. The kicks may be large enough to dramatically change
the radial distribution of young white dwarfs, giving them larger energies than
other stars in the cluster. As these energetic white dwarfs travel through the
cluster they can impart their excess energy on the other stars in the cluster.
This new heat source for globular clusters is expected to be largest during the
clusters' youth.


title: Locally Optimal Control of Quantum Systems with Strong Feedback

abstract:
  For quantum systems with high purity, we find all observables that, when
continuously monitored, maximize the instantaneous reduction in the von Neumann
entropy. This allows us to obtain all locally optimal feedback protocols with
strong feedback, and explicit expressions for the best such protocols for
systems of size N <= 4. We also show that for a qutrit the locally optimal
protocol is the optimal protocol for a given range of control times, and derive
an upper bound on all optimal protocols with strong feedback.


title:
Toward a halo mass function for precision cosmology: the limits of
  universality

abstract:
  We measure the mass function of dark matter halos in a large set of
collisionless cosmological simulations of flat LCDM cosmology and investigate
its evolution at z<~2. Halos are identified as isolated density peaks, and
their masses are measured within a series of radii enclosing specific
overdensities. We argue that these spherical overdensity masses are more
directly linked to cluster observables than masses measured using the
friends-of-friends algorithm (FOF), and are therefore preferable for accurate
forecasts of halo abundances. Our simulation set allows us to calibrate the
mass function at z=0 for virial masses in the range 10^{11} Msol/h < M <
10^{15} Msol/h, to <~ 5%. We derive fitting functions for the halo mass
function in this mass range for a wide range of overdensities, both at z=0 and
earlier epochs. In addition to these formulae, which improve on previous
approximations by 10-20%, our main finding is that the mass function cannot be
represented by a universal fitting function at this level of accuracy. The
amplitude of the "universal" function decreases monotonically by ~20-50%,
depending on the mass definition, from z=0 to 2.5. We also find evidence for
redshift evolution in the overall shape of the mass function.


title:
Modifications by QCD transition and $e^+e^-$ annihilation on analytic
  spectrum of relic gravitational waves in accelerating universe

abstract:
  As predicted by quantum chromodynamics(QCD), around $T\sim 190$ MeV in the
early universe, the QCD transition occurs during which the quarks are combined
into the massive hadrons. This process reduces the effective relativistic
degree of freedom, and causes a change in the expansion behavior of the
universe. Similarly, the $e^+e^-$ annihilation occurred around $T\sim 0.5$ Mev
has the same kind of effect. Besides, the dark energy also drives the present
stage accelerating expansion. We study these combined effects on the relic
gravitational waves (RGWs). In our treatment, the QCD transition and the
$e^+e^-$ annihilation, each is respectively represented by a short period of
expansion inserted into the radiation era. Incorporating these effects, the
equation of RGWs is analytically solved for a spatially flat universe, evolving
from the inflation up to the current acceleration, and the spectrum of RGWs is
obtained, covering the whole range of frequency $>10^{-19}$ Hz. It is found
that the QCD transition causes a reduction of the amplitude of RGWs by $\sim
20%$ in the range $>10^{-9} $ Hz, and the $e^+e^-$ annihilation causes a
reduction $\sim 10%$ in the range $>10^{-12} $ Hz. In the presence of the dark
energy, the combination of the QCD transition and the $e^+e^-$ annihilation,
causes a larger reduction of the amplitude by $\sim 30% $ for the range
$>10^{-9} $ Hz, which covers the bands of operation of LIGO and LISA. By
analysis, it is shown that RGWs will be difficult to detect by the present
LIGO, but can be tested by LISA for certain inflationary models.


title:
Meta-nematic, smectic and crystalline phases of dipolar fermions in an
  optical lattice

abstract:
  It has been suggested that some strongly correlated matter might be
understood qualitatively in terms of liquid crystalline phases intervening
between the Fermi gas and the Wigner crystal or Mott insulator. We propose a
tunable realisation of this soft quantum matter physics in an ultra-cold gas.
It uses optical lattices and dipolar interactions to realise a particularly
simple model. Our analysis reveals a rich phase diagram featuring a
meta-nematic transition where the Fermi liquid changes dimensionality; a
smectic phase (stripes); and a crystalline, `checkerboard' phase.


title: Electronic shot noise in fractal conductors

abstract:
  By solving a master equation in the Sierpinski lattice and in a planar
random-resistor network, we determine the scaling with size L of the shot noise
power P due to elastic scattering in a fractal conductor. We find a power-law
scaling P ~ L^(d_f-2-alpha), with an exponent depending on the fractal
dimension d_f and the anomalous diffusion exponent alpha. This is the same
scaling as the time-averaged current I, which implies that the Fano factor
F=P/2eI is scale independent. We obtain a value F=1/3 for anomalous diffusion
that is the same as for normal diffusion, even if there is no smallest length
scale below which the normal diffusion equation holds. The fact that F remains
fixed at 1/3 as one crosses the percolation threshold in a random-resistor
network may explain recent measurements of a doping-independent Fano factor in
a graphene flake.


title: New aspects of the purity and information of an entangled qubit pair

abstract:
  In this article, we investigate the purity dynamics of entangled 2 two-level
atoms interacting with a single quantized electromagnetic field. We show that
the purity of the qubit pairs depends on the initial state of the atomic
system. It is found that the superposition case is the best choice to generate
entangled states with high purity and hence high entanglement. It is clear that
the purity of one qubit can be purified at the expense of the other pair
through the phenomena of purity swapping. The mean photon number plays an
important role in increasing the purity. The robustness of the quantum channel
is investigated in the presence of individual attacks, where we study the
separability of these channels and evaluate its fidelity. Finally, we use the
partial entangled states as quantum channels to perform the original coding
protocol. We find that Bob can obtain the coded information with reasonable
percentage. The inequality of security is tested, where we determine the
interval of times in which Alice and Bob can communicatesecurely. These
intervals depend on the type of error and the structure of the initial atomic
system


title:
A pitfall in the use of extended likelihood for fitting fractions of
  pure samples in mixed samples

abstract:
  The paper elucidates, with an analytic example, a subtle mistake in the
application of the extended likelihood method to the problem of determining the
fractions of pure samples in a mixed sample from the shape of the distribution
of a random variable. This mistake, which affects two widely used software
packages, leads to a misestimate of the errors.


title: Nonlinear spectroscopy of photons bound to one atom

abstract:
  Optical nonlinearities typically require macroscopic media, thereby making
their implementation at the quantum level an outstanding challenge. Here we
demonstrate a nonlinearity for one atom enclosed by two highly reflecting
mirrors. We send laser light through the input mirror and record the light from
the output mirror of the cavity. For weak laser intensity, we find the
vacuum-Rabi resonances. But for higher intensities, we find an additional
resonance. It originates from the fact that the cavity can accommodate only an
integer number of photons and that this photon number determines the
characteristic frequencies of the coupled atom-cavity system. We selectively
excite such a frequency by depositing at once two photons into the system and
find a transmission which increases with the laser intensity squared. The
nonlinearity differs from classical saturation nonlinearities and is direct
spectroscopic proof of the quantum nature of the atom-cavity system. It
provides a photon-photon interaction by means of one atom, and constitutes a
step towards a two-photon gateway or a single-photon transistor.


title: Layered Structures Favor Superconductivity in Compressed Solid SiH$_{4}$

abstract:
  The electronic and lattice dynamical properties of compressed solid SiH$_{4}$
have been calculated in the pressure range up to 300 GPa with density
functional theory. We find that structures having a layered network with
eight-fold SiH$_{8}$ coordination favor metallization and superconductivity.
SiH$_{4}$ in these layered structures is predicted to have superconducting
transition temperatures ranging from 20 to 80 K, thus presenting new
possibilities for exploring high temperature superconductivity in this
hydrogen-rich system.


title: Thin, thick and dark discs in LCDM

abstract:
  In a LCDM cosmology, the Milky Way accretes satellites into the stellar disc.
We use cosmological simulations to assess the frequency of near disc plane and
higher inclination accretion events, and collisionless simulations of satellite
mergers to quantify the final state of the accreted material and the effect on
the thin disc. On average, a Milky Way-sized galaxy has 3 subhalos with
vmax>80km/s; 7 with vmax>60km/s; and 15 with vmax>40km/s merge at redshift z>1.
Assuming isotropic accretion, a third of these merge at an impact angle <20
degrees and are dragged into the disc plane by dynamical friction. Their
accreted stars and dark matter settle into a thick disc. The stellar thick disc
qualitatively reproduces the observed thick disc at the solar neighbourhood,
but is less massive by a factor ~2-10. The dark matter disc contributes 0.25-1
times the halo density at the solar position. Although not likely to be
dynamically interesting, the dark disc has important implications for the
direct detection of dark matter because of its low velocity with respect to the
Earth. Higher inclination encounters (>20 degrees) are twice as likely as low
inclination ones. These lead to structures that closely resemble the recently
discovered inner/outer stellar halos. They also do more damage to the Milky Way
stellar disc creating a more pronounced flare, and warp; both long-lived and
consistent with current observations. The most massive mergers (vmax>80km/s)
heat the thin disc enough to produce a thick disc. These heated thin disc stars
are essential for obtaining a thick disc as massive as that seen in the Milky
Way; they likely comprise some ~50-90% of the thick disc stars. The Milky Way
thin disc must reform from fresh gas after z=1 [abridged].


title: Effect of Cd2+ on the Growth and Thermal Properties of K2SO4 crystal

abstract:
  Single crystals of pure and Cd2+ doped potassium sulfate were grown from
aqueous solutions by the slow evaporation technique. From nutrient solutions
with a CdSO4 concentration of 4wt.% crystals containing 0.014wt.% dopant
concentration could be obtained. The X-ray diffraction patterns of powdered
crystals confirmed their crystal structures for both cases. Thermal analysis of
pure crystals shows that the alpha-beta phase transformation peak around 580
deg C is superimposed with spurious effects, while for Cd2+ doped crystals this
is not the case. The thermal hysteresis of the phase transition is 8 K for
undoped K2SO4 and is reduced to 3.5 K for K2SO4:Cd2+. Compared to undoped
crystals, the optical transmittance of Cd2+ doped crystals is higher.


title: An N-body/SPH Study of Isolated Galaxy Mass Density Profiles

abstract:
  We investigate the evolution of mass density profiles in secular disk galaxy
models, paying special attention to the development of a two-component profile
from a single initial exponential disk free of cosmological evolution (i.e., no
accretion or interactions). As the source of density profile variations, we
examine the parameter space of the spin parameter, halo concentration, virial
mass, disk mass and bulge mass, for a total of 162 simulations in the context
of a plausible model of star formation and feedback (GADGET-2). The evolution
of the galaxy mass density profile, including the development of a
two-component profile with an inner and outer segment, is controlled by the
ratio of the disk mass fraction, $m_{d}$, to the halo spin parameter,
$\lambda$. The location of the break between the two components and speed at
which it develops is directly proportional to $m_{d}/\lambda$; the amplitude of
the transition between the inner and outer regions is however controlled by the
ratio of halo concentration to virial velocity. The location of the divide
between the inner and outer profile does not change with time. (Abridged)


title: Distributed authentication for randomly compromised networks

abstract:
  We introduce a simple, practical approach with probabilistic
information-theoretic security to solve one of quantum key distribution's major
security weaknesses: the requirement of an authenticated classical channel to
prevent man-in-the-middle attacks. Our scheme employs classical secret sharing
and partially trusted intermediaries to provide arbitrarily high confidence in
the security of the protocol. Although certain failures elude detection, we
discuss preemptive strategies to reduce the probability of failure to an
arbitrarily small level: probability of such failures is exponentially
suppressed with increases in connectivity (i.e., connections per node).


title: The Galaxy Population Hosting Gamma-Ray Bursts

abstract:
  We present the most extensive and complete study of the properties for the
largest sample (46 objects) of gamma-ray burst (GRB) host galaxies. The
redshift interval and the mean redshift of the sample are 0<z<6.3 and z=0.96
(look-back time: 7.2 Gyr), respectively; 89% of the hosts are at z <~ 1.6.
Optical-near-infrared (NIR) photometry and spectroscopy are used to derive
stellar masses, star formation rates (SFRs), dust extinctions and
metallicities. The average stellar mass is 10^9.3 M_sun, with a 1 sigma
dispersion of 0.8 dex. The average metallicity for a subsample of 17 hosts is
about 1/6 solar and the dust extinction in the visual band (for a subsample of
10 hosts) is A_V=0.5. We obtain new relations to derive SFR from [OII] or UV
fluxes, when Balmer emission lines are not available. SFRs, corrected for dust
extinction, aperture-slit loss and stellar Balmer absorption are in the range
0.01-36 M_sun yr^-1. The median SFR per unit stellar mass (specific SFR) is 0.8
Gyr^-1. Equivalently the inverse quantity, the median formation timescale is
1.3 Gyr. Most GRBs are associated with the death of young massive stars, more
common in star-forming galaxies. Therefore GRBs are an effective tool to detect
star-forming galaxies in the universe. Star-forming galaxies at z<1.6 are a
faint and low-mass population, hard to detect by conventional optical-NIR
surveys, unless a GRB event occurs. There is no compelling evidence that GRB
hosts are peculiar galaxies. More data on the subclass of short GRB are
necessary to establish the nature of their hosts.


title: Towards ultrametric theory of turbulence

abstract:
  Relation of ultrametric analysis, wavelet theory and cascade models of
turbulence is discussed. We construct the explicit solutions for the nonlinear
ultrametric integral equation with quadratic nonlinearity. These solutions are
built by means of the recurrent hierarchical procedure which is analogous to
the procedure used for the cascade models of turbulence.


title: The Blume-Emery-Griffiths Spin Glass and Inverted Tricritical Points

abstract:
  The Blume-Emery-Griffiths spin glass is studied by renormalization-group
theory in d=3. The boundary between the ferromagnetic and paramagnetic phases
has first-order and two types of second-order segments. This topology includes
an inverted tricritical point, first-order transitions replacing second-order
transitions as temperature is lowered. The phase diagrams show disconnected
spin-glass regions, spin-glass and paramagnetic reentrances, and complete
reentrance, where the spin-glass phase replaces the ferromagnet as temperature
is lowered for all chemical potentials.


title:
The Path to Buried Treasure: Paving the Way to the FLAMINGOS-2 Galactic
  Center Survey with IR and X-ray Observations

abstract:
  I describe the IR and X-ray campaign we have undertaken to determine the
nature of the faint discrete X-ray source population discovered by Chandra in
the Galactic Center. These results will provide the input to the FLAMINGOS-2
Galactic Center Survey (F2GCS). With FLAMINGOS-2's multi-object IR spectrograph
we will obtain 1000s of IR spectra of candidate X-ray source counterparts,
allowing us to efficiently identify the nature of these sources, and thus
dramatically increase the number of known X-ray binaries and CVs in the Milky
Way.


title: Sortable elements in infinite Coxeter groups

abstract:
  In a series of previous papers, we studied sortable elements in finite
Coxeter groups, and the related Cambrian fans. We applied sortable elements and
Cambrian fans to the study of cluster algebras of finite type and the
noncrossing partitions associated to Artin groups of finite type. In this
paper, as the first step towards expanding these applications beyond finite
type, we study sortable elements in a general Coxeter group W. We supply
uniform arguments which transform all previous finite-type proofs into uniform
proofs (rather than type by type proofs), generalize many of the finite-type
results and prove new and more refined results. The key tools in our proofs
include a skew-symmetric form related to (a generalization of) the Euler form
of quiver theory and the projection \pidown^c mapping each element of W to the
unique maximal c-sortable element below it in the weak order. The fibers of
\pidown^c essentially define the c-Cambrian fan. The most fundamental results
are, first, a precise statement of how sortable elements transform under (BGP)
reflection functors and second, a precise description of the fibers of
\pidown^c. These fundamental results and others lead to further results on the
lattice theory and geometry of Cambrian (semi)lattices and Cambrian fans.


title: Metastability Driven by Soft Quantum Fluctuation Modes

abstract:
  The semiclassical Euclidean path integral method is applied to compute the
low temperature quantum decay rate for a particle placed in the metastable
minimum of a cubic potential in a {\it finite} time theory. The classical path,
which makes a saddle for the action, is derived in terms of Jacobian elliptic
functions whose periodicity establishes the one-to-one correspondence between
energy of the classical motion and temperature (inverse imaginary time) of the
system. The quantum fluctuation contribution has been computed through the
theory of the functional determinants for periodic boundary conditions. The
decay rate shows a peculiar temperature dependence mainly due to the softening
of the low lying quantum fluctuation eigenvalues. The latter are determined by
solving the Lam\`{e} equation which governs the fluctuation spectrum around the
time dependent classical bounce.


title:
Combined experimental and theoretical investigation of the
  premartensitic transition in Ni$_2$MnGa

abstract:
  Ultraviolet-photoemission (UPS) measurements and supporting specific-heat,
thermal-expansion, resistivity and magnetic-moment measurements are reported
for the magnetic shape-memory alloy Ni$_2$MnGa over the temperature range $100K
< T < 250K$. All measurements detect clear signatures of the premartensitic
transition ($T_\mathrm{PM}\sim 247K$) and the martensitic transition
($T_\mathrm{M} \sim 196K$). Temperature-dependent UPS shows a dramatic
depletion of states (pseudogap) at $T_\mathrm{PM}$ located 0.3eV below the
Fermi energy. First-principles electronic structure calculations show that the
peak observed at 0.3eV in the UPS spectra for $T > T_\mathrm{PM}$ is due to the
Ni-d minority-spin electrons. Below $T_\mathrm{M}$ this peak disappears,
resulting in an enhanced density of states at energies around 0.8eV. This
enhancement reflects Ni-d and Mn-d electronic contributions to the
majority-spin density of states and is accompanied by significant
reconstruction of the Fermi surface.


title:
Arbitrary Coherent Superpositions of Quantized Vortices in Bose-Einstein
  Condensates from Orbital Angular Momentum Beams of Light

abstract:
  We recently proposed a scheme for the creation of coherent superpositions of
vortex states in Bose-Einstein condensates (BEC) using orbital angular momentum
(OAM) states of light [Phys. Rev. Lett. 95, 173601 (2005)]. Here we discuss
further technical details of the proposal, provide alternative,
time-reversal-symmetric scheme for transfer of a superposition of OAM states of
light to the BEC via a procedure analogous to the traditional STimulated Raman
Adiabatic Passage (STIRAP) technique, and discuss an alternative trap
configuration conducive for sustaining large charge vortices. Superpositions of
OAM states of light, created using experimental techniques, can be transfered
to an initially nonrotating BEC via a specially devised Raman coupling scheme.
The techniques proposed here open up avenues to study coherent interaction of
OAM states of light with matter. The study could also be employed for
performing various quantum information processing tasks with OAM states of
light--including a memory for a quantum state of the initial superposition.


title:
Remarks about decay widths of two-body nonleptonic and semileptonic $B$
  decays

abstract:
  We present a brief discussion about expressions of decay widths of exclusive
nonleptonic and semileptonic B decays at tree level including $l=0$ and $l=1$
mesons in final state. Our analysis is carried out assuming factorization
hypothesis and using parametrizations of hadronic matrix elements given in WSB
and ISGW quark models. Special interest is focused on dynamics of these
processes and several important ratios between decay widths to determine form
factors and decay constants are given.


title: On the "Causality Paradox" of Time-Dependent Density Functional Theory

abstract:
  I show that the so-called causality paradox of time-dependent density
functional theory arises from an incorrect formulation of the variational
principle for the time evolution of the density. The correct formulation not
only resolves the paradox in real time, but also leads to a new expression for
the causal exchange-correlation kernel in terms of Berry curvature.
Furthermore, I show that all the results that were previously derived from
symmetries of the action functional remain valid in the present formulation.
Finally, I develop a model functional theory which explicitly demonstrates the
workings of the new formulation.


title: Multi-Pion States in Lattice QCD and the Charged-Pion Condensate

abstract:
  The ground-state energies of systems containing up to twelve $\pi^+$'s in a
spatial volume V ~ (2.5 fm)^3 are computed in dynamical, mixed-action lattice
QCD at a lattice spacing of ~ 0.125 fm for four different values of the light
quark masses. Clean signals are seen for each ground state, allowing for a
precise extraction of both the $\pi^+\pi^+$ scattering length and
$\pi^+\pi^+\pi^+$-interaction from a correlated analysis of systems containing
different numbers of $\pi^+$'s. This extraction of the $\pi^+\pi^+$ scattering
length is consistent with than that from the $\pi^+\pi^+$-system alone. The
large number of systems studied here significantly strengthens the arguments
presented in our earlier work and unambiguously demonstrates the presence of a
low energy $\pi^+\pi^+\pi^+$-interaction. The equation of state of a $\pi^+$
gas is investigated using our numerical results and the density dependence of
the isospin chemical potential for these systems agrees well with the
theoretical expectations of leading order chiral perturbation theory. The
chemical potential is found to receive a substantial contribution from the
$\pi^+\pi^+\pi^+$-interaction at the lighter pion masses. An important
technical aspect of this work is the demonstration of the necessity of
performing propagator contractions in greater than double precision to extract
the correct results.

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


title: Baryogenesis via Leptogenesis in an inhomogeneous universe

abstract:
  We investigate the influence of primordial perturbations of the energy
density and space--time metric on the generation of the lepton and baryon
asymmetries. In the weak and strong washout regimes baryon isocurvature
perturbations with amplitudes of the same order as those of the CMB
perturbations are generated on scales of order of the respective Hubble scale.
They are, however, completely washed out by baryon and photon diffusion at the
later stages of the universe's evolution.


title: Magnetism and structure at a vacancy in graphene

abstract:
  The electronic structure, bonding and magnetism in graphene containing
vacancies are studied using density-functional methods. The single-vacancy
graphene ground state is spin polarized and structurally flat. The unpolarized
state is non planar only for finite segments. Systems containing periodic
arrays of vacancies displays magnetic transitions and metal-insulator
transitions.


title:
Comparative Monte Carlo Study of a Monolayer Growth in a Heteroepitaxial
  System in the Presence of Surface Defects

abstract:
  The adsorption of a metal monolayer or submonolayer for the systems
Ag/Au(100), Au/Ag(100), Ag/Pt(100), Pt/Ag(100), Au/Pt(100), Pt/Au(100),
Au/Pd(100) and Pd/Au(100) was studied by means of lattice Monte Carlo
simulations, in the presence of surface defects.


title:
Surfing at the wave fronts: the bidirectional movement of cargo
  particles driven by molecular motors

abstract:
  The collective behavior of molecular motor proteins have been investigated in
the literature using models to describe the long-time dynamics of a
unidimensional continuum motor distribution. Here, we consider the phenomena
related to the transport of particles (vesicles, organelles, virus, etc) in the
realm of these continuum motor systems. We argue that cargo movement may result
from its ability to perturb the existing motor distribution and to surf at the
resulting shock waves separating regions of different motor densities within
the transient regime. In this case, the observed bidirectionality of cargo
movement is naturally associated with reversals of shocks directions.
Comparison of the quantitative results predicted by this model with available
data for cargo velocity allows us to suggest that geometrical characteristics
of the transported particle shall determine the extension and intensity of the
perturbation it produces and thus, its dynamics. Possible implications of these
ideas to virus movement at the cell body are discussed in connection with their
distinguished morphological characteristics. Key words: collective effects of
molecular motors; cargo transport; non-linear partial differential equations;
shock waves.


title:
Real-time control of the periodicity of a standing wave: an optical
  accordion

abstract:
  We report an experimental method to create optical lattices with real-time
control of their periodicity. We demonstrate a continuous change of the lattice
periodicity from 0.96 $\mu$m to 11.2 $\mu$m in one second, while the center
fringe only moves less than 2.7 $\mu$m during the whole process. This provides
a powerful tool for controlling ultracold atoms in optical lattices, where
small spacing is essential for quantum tunneling, and large spacing enables
single-site manipulation and spatially resolved detection.


title:
Special Lagrangian fibrations, mirror symmetry and Calabi-Yau double
  covers

abstract:
  The first part of this paper is a review of the Strominger-Yau-Zaslow
conjecture in various settings. In particular, we summarize how, given a pair
(X,D) consisting of a Kahler manifold and an anticanonical divisor, families of
special Lagrangian tori in X-D and weighted counts of holomorphic discs in X
can be used to build a Landau-Ginzburg model mirror to X. In the second part we
turn to more speculative considerations about Calabi-Yau manifolds with
holomorphic involutions and their quotients. Namely, given a hypersurface H
representing twice the anticanonical class in a Kahler manifold X, we attempt
to relate special Lagrangian fibrations on X-H and on the (Calabi-Yau) double
cover of X branched along H; unfortunately, the implications for mirror
symmetry are far from clear.


title:
MeV sterile neutrinos in low reheating temperature cosmological
  scenarios

abstract:
  It is commonly assumed that the cosmological and astrophysical bounds on the
mixings of sterile with active neutrinos are much more stringent than those
obtained from laboratory measurements. We point out that in scenarios with a
very low reheating temperature T_RH << 100 MeV at the end of (the last episode
of) inflation or entropy creation, the abundance of sterile neutrinos becomes
largely suppressed with respect to that obtained within the standard framework.
Thus, in this case cosmological bounds become much less stringent than usually
assumed, allowing sterile neutrinos to be ``visible'' in future experiments.
Here, we concentrate on massive (mostly sterile) neutrinos heavier than 1 MeV.


title:
Integration of e^(x^n) and e^(-x^n) in forms of series, their
  applications in the field of differential equation; introducing generalized
  form of Skewness and Kurtosis; extension of starling's approximation

abstract:
  In this paper we tried a different approach to work out the integrals of
e^(x^n) and e^(-x^n). Integration by parts shows a nice pattern which can be
reduced to a form of series. We have shown both the indefinite and definite
integrals of the functions mentioned along with some essential properties e.g.
conditions of convergence of the series. Further more, we used the integrals in
form of series to find out series solution of differential equations of the
form x[(d^2 y)/(dx^2)]-(n-1)(dy/dx)-n^2 x^(2n-1)y-nx^n=0 and x[(d^2 y)/(dx^2)]
-(n-1)(dy/dx)-n^2x^(2n-1)y+(n-1)=0, using some non standard method. We
introduced modified Normal distribution incorporating some properties derived
from the above integrals and defined a generalized version of Skewness and
Kurtosis. Finally we extended Starling's approximation to limit [n to infinity
] (2n)! ~ 2n * \sqrt{(2\pi)} [(2n/e)]^(2n).


title: Filling factor dependence of the fractional quantum Hall effect gap

abstract:
  We directly measure the chemical potential jump in the low-temperature limit
when the filling factor traverses the nu = 1/3 and nu = 2/5 fractional gaps in
two-dimensional (2D) electron system in GaAs/AlGaAs single heterojunctions. In
high magnetic fields B, both gaps are linear functions of B with slopes
proportional to the inverse fraction denominator, 1/q. The fractional gaps
close partially when the Fermi level lies outside. An empirical analysis
indicates that the chemical potential jump for an IDEAL 2D electron system, in
the highest accessible magnetic fields, is proportional to q^{-1}B^{1/2}.


title: The structure of N(1535) in the aspect of chiral symmetry

abstract:
  The structure of N(1535) is discussed in dynamical and symmetry aspects based
on chiral symmetry. We find that the N(1535) in chiral unitary model has
implicitly some components other than meson-baryon one. We also discuss the
N(1535) in the chiral doublet picture.


title: Electrodynamics of the vanadium oxides VO2 and V2O3

abstract:
  The optical/infrared properties of films of vanadium dioxide (VO2) and
vanadium sesquioxide (V2O3) have been investigated via ellipsometry and
near-normal incidence reflectance measurements from far infrared to ultraviolet
frequencies. Significant changes occur in the optical conductivity of both VO2
and V2O3 across the metal-insulator transitions at least up to (and possibly
beyond) 6 eV. We argue that such changes in optical conductivity and electronic
spectral weight over a broad frequency range is evidence of the important role
of electronic correlations to the metal-insulator transitions in both of these
vanadium oxides. We observe a sharp optical transition with possible final
state (exciton) effects in the insulating phase of VO2. This sharp optical
transition occurs between narrow a1g bands that arise from the
quasi-one-dimensional chains of vanadium dimers. Electronic correlations in the
metallic phases of both VO2 and V2O3 lead to reduction of the kinetic energy of
the charge carriers compared to band theory values, with paramagnetic metallic
V2O3 showing evidence of stronger correlations compared to rutile metallic VO2.


title: Unconventional sign-reversing superconductivity in LaFeAsO_(1-x)F_x

abstract:
  We argue that the newly discovered superconductivity in a nearly magnetic,
Fe-based layered compound is unconventional and mediated by antiferromagnetic
spin fluctuations, though different from the usual superexchange and specific
to this compound. This resulting state is an example of extended s-wave pairing
with a sign reversal of the order parameter between different Fermi surface
sheets. The main role of doping in this scenario is to lower the density of
states and suppress the pair-breaking ferromagnetic fluctuations.


title: Spin-Orbit Coupling and Ion Displacements in Multiferroic TbMnO3

abstract:
  The electronic and magnetic properties of TbMnO3 leading to its ferroelectric
(FE) polarization were investigated on the basis of relativistic density
functional theory (DFT) calculations. In agreement with experiment, we show
that the spin-spiral plane of TbMnO3 can be either the bc- or ab-plane, but not
the ac-plane. As for the mechanism of FE polarization, our work reveals that
the "pure electronic" model by Katsura, Nagaosa and Balatsky (KNB) is
inadequate in predicting the absolute direction of FE polarization. For the
ab-plane spin-spiral state of TbMnO3, the direction of FE polarization
predicted by the KNB model is opposite to that predicted by DFT calculations.
In determining the magnitude and the absolute direction of FE polarization in
spin-spiral states, it is found crucial to consider the displacements of the
ions from their ecntrosymmetric positions.


title: "Detuned" f(R) gravity and dark energy

abstract:
  In gravity theories derived from a f(R) Lagrangian, matter is usually
supposed to be minimally coupled to the metric, which hence defines a ``Jordan
frame.'' However, since the field equations are fourth order, gravity possesses
an extra degree of freedom on top of the standard graviton, as is manifest from
its equivalent description in the conformally related, Einstein, frame. We
introduce explicitly this extra scalar degree of freedom in the action and
couple it to matter, so that the original metric no longer defines a Jordan
frame. This ``detuning'' puts f(R) gravity into a wider class of scalar--tensor
theories. We argue that a ``chameleon-like'' detuning tracing the background
matter density may provide purely gravitational models which account for the
present acceleration of the universe and evade local gravity constraints.


title: Massive Rigid String Model and its Supersymmetric Extension

abstract:
  We discuss a rigid string model proposed by Casalbuoni and Longhi.
Constraints for the massive states are solved to find the physical states and
the mass spectrum. We also find its supersymmetric extension with the kappa
symmetry. The supersymmetry transformations are found starting from on-shell
transformations using the Dirac bracket.


title:
Classical Limits of Scalar and Tensor Gauge Operators Based on the
  Overlap Dirac Matrix

abstract:
  It was recently proposed by the second author to consider lattice
formulations of QCD in which complete actions, including the gauge part, are
built explicitly from a given Dirac operator D. In a simple example of such
theory, the gauge action is proportional to the trace of Ginsparg-Wilson
operator D chosen to define the quark dynamics. This construction relies on the
proposition that the classical limit of lattice gauge operator tr D(x,x) is
proportional to tr F.F(x) (up to an additive constant). Here we show this for
the case of the overlap Dirac operator using both analytical and numerical
methods. We carry out the same analysis also for the tensor component of D,
which is similarly related to the field-strength tensor F, and obtain results
identical to our previous derivation that used different approach. The
corresponding proportionality constants are computed to high precision for wide
range of the negative mass parameter values, and it is verified that they are
the same in finite and infinite volumes.


title: Higher topological cyclic homology and the Segal conjecture for tori

abstract:
  We investigate higher topological cyclic homology as an approach to studying
chromatic phenomena in homotopy theory. Higher topological cyclic homology is
constructed from the fixed points of a version of topological Hochschild
homology based on the n-dimensional torus, and we propose it as a
computationally tractable cousin of n-fold iterated algebraic K-theory.
  The fixed points of toral topological Hochschild homology are related to one
another by restriction and Frobenius operators. We introduce two additional
families of operators on fixed points, the Verschiebung, indexed on
self-isogenies of the n-torus, and the differentials, indexed on n-vectors. We
give a detailed analysis of the relations among the restriction, Frobenius,
Verschiebung, and differentials, producing a higher analog of the structure
Hesselholt and Madsen described for 1-dimensional topological cyclic homology.
  We calculate two important pieces of higher topological cyclic homology,
namely topological restriction homology and topological Frobenius homology, for
the sphere spectrum. The latter computation allows us to establish the Segal
conjecture for the torus, which is to say to completely compute the cohomotopy
type of the classifying space of the torus.


title: Vector spaces as unions of proper subspaces

abstract:
  In this note, we find a sharp bound for the minimal number (or in general,
indexing set) of subspaces of a fixed (finite) codimension needed to cover any
vector space V over any field. If V is a finite set, this is related to the
problem of partitioning V into subspaces.


title: Irreducible multi-particle correlations in states without maximal rank

abstract:
  In a system of $n$ quantum particles, the correlations are classified into a
series of irreducible $k$-particle correlations ($2\le k\le n$), where the
irreducible $k$-particle correlation is the correlation appearing in the states
of $k$ particles but not existing in the states of $k-1$ particles. A measure
of the degree of irreducible $k$-particle correlation is defined based on the
maximal entropy construction. By adopting a continuity approach, we overcome
the difficulties in calculating the degrees of irreducible multi-particle
correlations for the multi-particle states without maximal rank. In particular,
we obtain the degrees of irreducible multi-particle correlations in the
$n$-qubit stabilizer states and the $n$-qubit generalized GHZ states, which
reveals the distribution of multi-particle correlations in these states.


title: Entanglement of Multipartite Schmidt-correlated States

abstract:
  We generalize the Schmidt-correlated states to multipartite systems. The
related equivalence under SLOCC, the separability, entanglement witness,
entanglement measures of negativity, concurrence and relative entropy are
investigated in detail for the generalized Schmidt-correlated states.


title: Quasitoric manifolds over a product of simplices

abstract:
  A quasitoric manifold (resp. a small cover) is a $2n$-dimensional (resp. an
$n$-dimensional) smooth closed manifold with an effective locally standard
action of $(S^1)^n$ (resp. $(\mathbb Z_2)^n$) whose orbit space is
combinatorially an $n$-dimensional simple convex polytope $P$. In this paper we
study them when $P$ is a product of simplices. A generalized Bott tower over
$\F$, where $\F=\C$ or $\R$, is a sequence of projective bundles of the Whitney
sum of $\F$-line bundles starting with a point. Each stage of the tower over
$\F$, which we call a generalized Bott manifold, provides an example of
quasitoric manifolds (when $\F=\C$) and small covers (when $\F=\R$) over a
product of simplices. It turns out that every small cover over a product of
simplices is equivalent (in the sense of Davis and Januszkiewicz \cite{DJ}) to
a generalized Bott manifold. But this is not the case for quasitoric manifolds
and we show that a quasitoric manifold over a product of simplices is
equivalent to a generalized Bott manifold if and only if it admits an almost
complex structure left invariant under the action. Finally, we show that a
quasitoric manifold $M$ over a product of simplices is homeomorphic to a
generalized Bott manifold if $M$ has the same cohomology ring as a product of
complex projective spaces with $\Q$ coefficients.


title:
Transport magnetic currents driven by moving kink crystal in chiral
  helimagnets

abstract:
  We show that the bulk transport magnetic current is generated by the moving
magnetic kink crystal (chiral soliton lattice) formed in the chiral helimagnet
under the static magnetic field applied perpendicular to the helical axis. The
current is caused by the non-equilibrium transport momentum with the kink mass
being determined by the spin fluctuations around the kink crystal state. An
emergence of the transport magnetic currents is then a consequence of the
dynamical off-diagonal long range order along the helical axis. We derive an
explicit formula for the inertial mass of the kink crystal and the current in
the weak field limit.


title: Hyperbolic volume and Heegaard distance

abstract:
  We prove (Theorem~1.5) that there exists a constant $\Lambda > 0$ so that if
$M$ is a $(\mu,d)$-generic complete hyperbolic 3-manifold of volume $\vol[M] <
\infty$ and $\Sigma \subset M$ is a Heegaard surface of genus $g(\Sigma) >
\Lambda \vol[M]$, then $d(\Sigma) \leq 2$, where $d(\Sigma)$ denotes the
distance of $\Sigma$ as defined by Hempel.
  The key for the proof of the main result is Theorem~1.8 which is on
independent interest. There we prove that if $M$ is a compact 3-manifold that
can be triangulated using at most $t$ tetrahedra (possibly with missing or
truncated vertices), and $\Sigma$ is a Heegaard surface for $M$ with $g(\Sigma)
\geq 76t+26$, then $d(\Sigma) \leq 2$.


title:
The vibrational stability and electronic structure of B80 fullerene-like
  cage

abstract:
  We investigate the vibrational stability and the electronic structure of the
proposed icosahedral fullerene-like cage structure of B80 [Szwacki, Sadrzadeh,
and Yakobson, Phys. Rev. Lett. {\bf 98}, 166804 (2007)] by an all electron
density functional theory using polarized Gaussian basis functions containing
41 basis functions per atom. The vibrational analysis of B$_{80}$ indicates
that the icosahedral structure is vibrationally unstable with 7 imaginary
frequencies. The equilibrium structure has $T_h$ symmetry and a {\em smaller}
gap of 0.96 eV between the highest occupied and lowest unoccupied molecular
orbital energy levels compared to the icosahedral structure. The static dipole
polarizability of B$_{80}$ cage is 149 \AAA and the first ionization energy is
6.4 eV. The B$_{80}$ cage has rather large electron affinity of 3 eV making it
useful candidate as electron acceptor if it is synthesized. The infra-red and
Raman spectra of the highly symmetric structure are characterized by a few
absorption peaks.


title: Resolving the chemistry in the disk of TW Hydrae I. Deuterated species

abstract:
  We present Submillimeter Array (SMA) observations of several deuterated
species in the disk around the classical T Tauri star TW Hydrae at arcsecond
scales, including detections of the DCN J=3-2 and DCO+ J=3-2 lines, and upper
limits to the HDO 3(1,2)-2(2,1), ortho-H2D+ 1(1,0)-1(1,1) and para-D2H+
1(1,0)-1(0,1) transitions. We also present observations of the HCN J=3-2, HCO+
J=3-2 and H13CO+ J=4-3 lines for comparison with their deuterated
isotopologues. We constrain the radial and vertical distributions of various
species in the disk by fitting the data using a model where the molecular
emission from an irradiated accretion disk is sampled with a 2D Monte Carlo
radiative transfer code. We find that the distribution of DCO+ differs markedly
from that of HCO+. The D/H ratios inferred change by at least one order of
magnitude (0.01 to 0.1) for radii <30 AU to >70 AU and there is a rapid falloff
of the abundance of DCO+ at radii larger than 90 AU. Using a simple analytical
chemical model, we constrain the degree of ionization, x(e-)=n(e-)/n(H2), to be
~10^-7 in the disk layer(s) where these molecules are present. Provided the
distribution of DCN follows that of HCN, the ratio of DCN to HCN is determined
to be 1.7\pm0.5 \times 10^-2; however, this ratio is very sensitive to the
poorly constrained vertical distribution of HCN. The resolved radial
distribution of DCO+ indicates that {\it in situ} deuterium fractionation
remains active within the TW Hydrae disk and must be considered in the
molecular evolution of circumstellar accretion disks.