title: Vector magnetic fields of Solar Granulation

abstract:
  Observations of quiet Sun from the Solar Optical
Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft would
reveal the magnetic characters of the solar photosphere. By making use of the
deep mode observations of three quiet regions, we have statistically studied
the vector magnetic fields of solar granulation. More than 2000 normal granules
are manually selected to form a sample. It is recognized that some granules are
even darker than the mean photosphere in intensity, and there is a linear
correlation between intensity and Doppler velocity in granules.
  The distributions of longitudinal and transverse apparent magnetic flux
densities, Doppler velocity and continuum intensity of granules are obtained,
and their unsigned magnetic flux measured. Two approaches are carried out in
this study. First we obtained the magnetic properties of granulation by
averaging the measurements for all the sampling granules. Secondly, we
reconstructed an average granular cell based on a sub-sample, and obtained the
detailed distribution of apparent magnetic flux density within the model
granular cell. All the results have been compared with that of inter-granular
lanes and a few typical abnormal granules.


title: Quantum wormhole as a Ricci flow

abstract:
  The idea is considered that a quantum wormhole in a spacetime foam can be
described as a Ricci flow. In this interpretation the Ricci flow is a
statistical system and every metric in the Ricci flow is a microscopical state.
The probability density of the microscopical state is connected with a
Perelman's functional of a rescaled Ricci flow.


title: On the Brightening Propagation of Post-Flare Loops Observed by TRACE

abstract:
  Examining flare data observed by TRACE satellite from May 1998 to December
2006, we choose 190 (151 M-class and 39 X-class) flare events which display
post-flare loops (PFLs), observed by 171 \AA and 195 \AA wavelengths. 124 of
the 190 events exhibit flare ribbons (FRs), observed by 1600 \AA images. We
investigate the propagation of the brightening of these PFLs along the neutral
lines and the separation of the FRs perpendicular to the neutral lines. In most
of the cases, the length of the FRs ranges from 20 Mm to 170 Mm. The
propagating duration of the brightening is from 10 to 60 minutes, and from 10
minutes to 70 minutes for the separating duration of the FRs. The velocities of
the propagation and the separation range from 3 km/s to 39 km/s and 3 km/s to
15 km/s, respectively. Both of the propagating velocities and the separating
velocities are associated with the flare strength and the length of the FRs. It
appears that the propagation and the separation are dynamically coupled, that
is the greater the propagating velocity is, the faster the separation is.
Furthermore, a greater propagating velocity corresponds to a greater
deceleration (or acceleration). These PFLs display three types of propagating
patterns. Type I propagation, which possesses about half of all the events, is
that the brightening begins at the middle part of a set of PFLs, and propagates
bi-directionally towards its both ends. Type II, possessing 30%, is that the
brightening firstly appears at one end of a set of PFLs, then propagates to the
other end. The remnant belongs to Type III propagation which displays that the
initial brightening takes place at two (or more than two) positions on two (or
more than two) sets of PFLs, and each brightening propagates bi-directionally
along the neutral line.


title: Splitting of Sharply 2-Transitive Groups of Characteristic 3

abstract:
  We give a group theoretic proof of the splitting of sharply 2-transitive
groups of characteristic 3.


title: Single Top Quarks at the Tevatron

abstract:
  After many years searching for electroweak production of top quarks, the
Tevatron collider experiments have now moved from obtaining first evidence for
single top quark production to an impressive array of measurements that test
the standard model in several directions. This paper describes measurements of
the single top quark cross sections, limits set on the CKM matrix element
|Vtb|, searches for production of single top quarks produced via
flavor-changing neutral currents and from heavy W-prime and H+ boson
resonances, and studies of anomalous Wtb couplings. It concludes with
projections for future expected significance as the analyzed datasets grow.


title: MOOPPS: An Optimization System for Multi Objective Scheduling

abstract:
  In the current paper, we present an optimization system solving multi
objective production scheduling problems (MOOPPS). The identification of Pareto
optimal alternatives or at least a close approximation of them is possible by a
set of implemented metaheuristics. Necessary control parameters can easily be
adjusted by the decision maker as the whole software is fully menu driven. This
allows the comparison of different metaheuristic algorithms for the considered
problem instances. Results are visualized by a graphical user interface showing
the distribution of solutions in outcome space as well as their corresponding
Gantt chart representation.
  The identification of a most preferred solution from the set of efficient
solutions is supported by a module based on the aspiration interactive method
(AIM). The decision maker successively defines aspiration levels until a single
solution is chosen.
  After successfully competing in the finals in Ronneby, Sweden, the MOOPPS
software has been awarded the European Academic Software Award 2002
(http://www.bth.se/llab/easa_2002.nsf)


title: On NP complete problems I

abstract:
  We study the quadratic residue problem known as an NP complete problem by way
of the prime number and show that a nondeterministic polynomial process does
not belong to the class P because of a random distribution of solutions for the
quadratic residue problem.


title:
Oscillations of Dirac and Majorana neutrinos in matter and a magnetic
  field

abstract:
  We study the evolution of massive mixed Dirac and Majorana neutrinos in
matter under the influence of a transversal magnetic field. The analysis is
based on relativistic quantum mechanics. We solve exactly the evolution
equation for relativistic neutrinos, find the neutrino wave functions, and
calculate the transition probability for spin-flavor oscillations. We analyze
the dependence of the transition probability on the external fields and compare
the cases of Dirac and Majorana neutrinos. The evolution of Majorana particles
in vacuum is also studied and correction terms to the standard oscillation
formula are derived and discussed. As a possible application of our results we
discuss the spin-flavor transitions in supernovae.


title: MHD turbulence in a channel with spanwise magnetic field

abstract:
  The effect of a uniform spanwise magnetic field on a turbulent channel flow
is investigated for the case of low magnetic Reynolds number. DNS and LES
computations are performed for two values of the hydrodynamic Reynolds number
(10^4 and 2\times 10^4) and the Hartmann number varying in a wide range. It is
shown that the main effect of the magnetic field is the suppression of
turbulent velocity fluctuations and momentum transfer in the wall-normal
direction. This leads to drag reduction and transformation of the mean flow
profile. The centerline velocity grows, the mean velocity gradients near the
wall decrease, and the typical horizontal dimensions of the coherent structures
enlarge upon increasing the Hartmann number. Comparison between LES and DNS
results shows that the dynamic Smagorinsky model accurately reproduces the flow
transformation.


title: Fonction constante et d\'eriv\'ee nulle : un r\'esultat si trivial..

abstract:
  We study various proofs of the caracterization of constant functions, more
precisely of the theorem: a derivable function, defined on a real interval, is
constant if, and only if, its derivative is null. Our aim is to study the
relationships of these proofs with the mathematical curriculum of secondary
schools and the begining of undergraduate studies in France, from various point
of views (epistemological, historical, didactical).


title: Searching for the metal-weak thick disc in the solar neighbourhood

abstract:
  An abundance analysis is presented of 60 metal-poor stars drawn from
catalogues of nearby stars provided by Ariyanto et al. (2005) and Schuster et
al. (2006). In an attempt to isolate a sample of metal-weak thick disc stars,
we applied the kinematic criteria $V_{\rm rot} \geq 100$ km s$^{-1}$,
$|U_{LSR}| \leq 140$ km s$^{-1}$, and $|W_{LSR}| \leq 100$ km s$^{-1}$.
Fourteen stars satisfying these criteria and having [Fe/H] $\leq -1.0$ are
included in the sample of 60 stars. Eight of the 14 have [Fe/H] $\geq -1.3$ and
may be simply thick disc stars of slightly lower than average [Fe/H]. The other
six have [Fe/H] from -1.3 to -2.3 and are either metal-weak thick disc stars or
halo stars with kinematics mimicking those of the thick disc. The sample of 60
stars is completed by eight thick disc stars, 20 stars of a hybrid nature (halo
or thick disc stars), and 18 stars with kinematics distinctive of the halo.


title: Magnetic bottles on geometrically finite hyperbolic surfaces

abstract:
  We consider a magnetic Laplacian on a geometrically finite hyperbolic
surface, when the corresponding magnetic field is infinite at the boundary at
infinity. We prove that the counting function of the eigenvalues has a
particular asymptotic behaviour when the surface has an infinite area.


title:
Modeling of Plasma-Assisted Conversion of Liquid Ethanol into Hydrogen
  Enriched Syngas in the Nonequilibrium Electric Discharge Plasma-Liquid System

abstract:
  In this work we report recent results of our experimental and theoretical
studies related to plasma conversion of liquid ethanol into hydrogen-enriched
syngas in the plasma-liquid system with the electric discharge in a gas channel
with liquid wall using available diagnostics and numerical modeling.


title:
Interplay between one-dimensional confinement and crystallographic
  anisotropy in ballistic hole quantum wires

abstract:
  We study the Zeeman splitting in induced ballistic 1D quantum wires aligned
along the [233] and [011] axes of a high mobility (311)A undoped
heterostructure. Our data shows that the g-factor anisotropy for magnetic
fields applied along the high symmetry [011] direction can be explained by the
1D confinement only. However when the magnetic field is along [233] there is an
interplay between the 1D confinement and 2D crystal anisotropy. This is
highlighted for the [233] wire by an unusual non-monotonic behavior of the
g-factor as the wire is made narrower.


title:
Mapping dust column density in dark clouds by using NIR scattered light
  : Case of the Lupus 3 dark cloud

abstract:
  We present a method of mapping dust column density in dark clouds by using
near-infrared scattered light. Our observations of the Lupus 3 dark cloud
indicate that there is a well defined relation between (1) the H-Ks color of an
individual star behind the cloud, i.e., dust column density, and (2) the
surface brightness of scattered light toward the star in each of the J, H, and
Ks bands. In the relation, the surface brightnesses increase at low H-Ks
colors, then saturate and decrease with increasing H-Ks. Using a simple
one-dimensional radiation transfer model, we derive empirical equations which
plausibly represent the observed relationship between the surface brightness
and the dust column density. By using the empirical equations, we estimate dust
column density of the cloud for any directions toward which even no background
stars are seen. We obtain a dust column density map with a pixel scale of 2.3 x
2.3 arcsec^2 and a large dynamic range up to Av = 50 mag. Compared to the
previous studies by Juvela et al., this study is the first to use color excess
of the background stars for calibration of the empirical relationship and to
apply the empirical relationship beyond the point where surface brightness
starts to decrease with increasing column density.


title:
Ferromagnetism in Mn Substituted Zirconia: A Density-functional Theory
  Study

abstract:
  We study the electronic structure and magnetism of 25% Mn substituted cubic
Zirconia (ZrO2) with several homogeneous and heterogeneous doping profiles
using density-functional theory calculations. We find that all doping profiles
show half-metallic ferromagnetism (HMF), and delta-doping is most energy
favorable while homogeneous doping has largest ferromagnetic stabilization
energy. Using crystal field theory, we discuss the formation scheme of HMF.
Finally, we speculate the potential spintronics applications for Mn doped ZrO2,
especially as spin direction controllment.


title: The UV luminosity function and star formation rate of the Coma cluster

abstract:
  We present estimates of the GALEX NUV and FUV luminosity functions (LFs) of
the Coma cluster, over a total area of ~9 deg^2 (~25 Mpc^2), i.e. from the
cluster center to the virial radius. Our analysis represents the widest and
deepest UV investigation of a nearby cluster of galaxies made to date. The Coma
UV LFs show a faint-end slope steeper than the one observed in the local field.
This difference, more evident in NUV, is entirely due to the contribution of
massive quiescent systems (e.g. ellipticals, lenticulars and passive spirals),
more frequent in high density environments. On the contrary, the shape of the
UV LFs for Coma star-forming galaxies does not appear to be significantly
different from that of the field, consistently with previous studies of local
and high redshift clusters. We demonstrate that such similarity is only a
selection effect, not providing any information on the role of the environment
on the star formation history of cluster galaxies. By integrating the UV LFs
for star-forming galaxies (corrected for the first time for internal dust
attenuation), we show that the specific star formation rate of Coma is
significantly lower than the integrated SSFR of the field and that Coma-like
clusters contribute only <7% of the total SFR density of the local universe.
Approximately 2/3 of the whole star-formation in Coma is occurring in galaxies
with M_star < 10^10 M_sol. The vast majority of star-forming galaxies has
likely just started its first dive into the cluster core and has not yet been
affected by the cluster environment. The total stellar mass accretion rate of
Coma is ~(0.6-1.8) x 10^12 M_sol Gyr^-1, suggesting that a significant fraction
of the population of lenticular and passive spirals observed today in Coma
could originate from infalling galaxies accreted between z~1 and z~0.


title: The Properties of Sub-mm Galaxies in Hierarchical Models

abstract:
  We use the combined GALFORM semi-analytical model of galaxy formation and
GRASIL spectrophotometric code to investigate the properties of galaxies
selected via their sub-mm emission. Our fiducial model has previously been
shown to fit the properties of local ULIRGs, as well as the number counts of
faint sub-mm galaxies. Here, we test the model in detail by comparing the SEDs
and stellar, dynamical, gas and halo masses of sub-mm galaxies against
observational data. We precisely mimic the sub-mm and radio selection function
of the observations and show that the predicted far-infrared properties of
model galaxies with S_850>5mJy and S_1.4>30uJy are in good agreement with
observations. Although the dust emission model does not assume a single dust
temperature, the far-infrared SEDs are well described by single component
modified black-body spectrum with characteristic temperature 32+/-5K. We also
find evidence that the observations may have uncovered evolution in the
far-infrared--radio relation in ULIRGs out to z~2. We show that the predicted
redshift distribution of sub-mm galaxies provides a reasonable fit to the
observational data with a median redshift z=2.0, with the radio-selected subset
predicted to make up approximately 75% of the population. However, the
predicted K-band and mid-infrared (3--8um) flux densities of the sub-mm
galaxies (and LBGs) are up to a factor 10x fainter than observed. This
discrepancy may indicate that the stellar masses of the sub-mm galaxies in the
model are too low: M~10^10Mo, while observations suggest more massive systems,
M~10^11Mo. Finally, we discuss the potential modifications to the models which
may improve the fit to the observational data. [Abridged]


title: Least Squares and Shrinkage Estimation under Bimonotonicity Constraints

abstract:
  In this paper we describe active set type algorithms for minimization of a
smooth function under general order constraints, an important case being
functions on the set of bimonotone r-by-s matrices. These algorithms can be
used, for instance, to estimate a bimonotone regression function via least
squares or (a smooth approximation of) least absolute deviations. Another
application is shrinkage estimation in image denoising or, more generally,
regression problems with two ordinal factors after representing the data in a
suitable basis which is indexed by pairs (i,j) in {1,...,r}x{1,...,s}. Various
numerical examples illustrate our methods.


title:
Production of the neutral top-pion $\pi_{t}^{0}$ in association with a
  high-$p_{T}$ jet at the $LHC$

abstract:
  In the framework of the topcolor-assisted technicolor $(TC2)$ model, we study
production of the neutral top-pion $\pi_{t}^{0}$ in association with a
high-$p_{T}$ jet at the $LHC$, which proceeds via the partonic processes
$gg\longrightarrow \pi_{t}^{0}g$, $gq\longrightarrow \pi_{t}^{0}q$,
$q\bar{q}\longrightarrow \pi_{t}^{0}g$, $gb(\bar{b})\longrightarrow
\pi_{t}^{0}b(\bar{b})$, and $b\bar{b}\longrightarrow \pi_{t}^{0}g$. We find
that it is very challenging to detect the neutral top-pion $\pi_{t}^{0}$ via
the process $pp\longrightarrow \pi_{t}^{0}+jet+X\to t\bar{t}+jet+X$, while the
possible signatures of $\pi_{t}^{0}$ might be detected via the process
$pp\longrightarrow \pi_{t}^{0}+jet+X\to(\bar{t}c+t\bar{c})+jet+X$ at the $LHC$.


title:
Comparison of Raman spectra and vibrational density of states between
  graphene nanoribbons with different edges

abstract:
  Vibrational properties of graphene nanoribbons are examined with density
functional based tight-binding method and non-resonant bond polarization
theory. We show that the recently discovered reconstructed zigzag edge can be
identified from the emergence of high-energy vibrational mode due to strong
triple bonds at the edges. This mode is visible also in the Raman spectrum.
Total vibrational density of states of the reconstructed zigzag edge is
observed to resemble the vibrational density of states of armchair, rather than
zigzag, graphene nanoribbon. Edge-related vibrational states increase in energy
which corroborates increased ridigity of the reconstructed zigzag edge.


title: Cosmology with Unparticles

abstract:
  We discuss cosmological consequences of the existence of physics beyond the
standard model that exhibits Banks-Zaks and unparticle behavior in the UV and
IR respectively. We first derive the equation of state for unparticles and use
it to obtain the temperature dependence of the corresponding energy and entropy
densities. We then formulate the Boltzmann and Kubo equations for both the
unparticles and the Banks-Zaks particles, and use these results to determine
the equilibrium conditions between the standard model and the new physics. We
conclude by obtaining the constraints on the effective number of degrees of
freedom of unparticles imposed by Big-Bang nucleosynthesis.


title:
Galactic Halos Derived from LambdaCDM Cosmology Simulation and their
  Red-Shift Evolution

abstract:
  Galaxies can form in a sufficiently deep gravitational potential so that
efficient gas cooling occurs. We estimate that such potential is provided by a
halo of mass $M \gtsim M_{c} \approx 7.0 \times 10^{12} ~ (\Delta_{c}(z)
(1+z)^{3})^{-1/2} \Msun$, where $\Delta_{c}(z)$ is the mean overdensity of
spherically virialized objects formed at redshift $z$, and $M_{c} \approx 4.0
\times 10^{11} \Msun$ at $z = 0$. Based on this criterion, our galaxy samples
are constructed from cosmology simulation data by using HiFOF to select
subhalos in those FOF halos that are more massive than $M_{c}$. There are far
more dark subhalos than galaxy-hosting subhalos. Several tests against
observations have been performed to examine our galaxy samples, including the
differential galaxy mass functions, the galaxy space density, the projected two
point correlation functions (CF), the HODs, and the kinematic pair fractions.
These tests show good agreements. Based on the consistency with observations,
our galaxy sample is believed to correctly represent galaxies in real universe,
and can be used to study other unexplored galaxy properties.


title:
A housing-demographic multi-layered nonlinear model to test regulation
  strategies

abstract:
  We propose a novel multi-layered nonlinear model that is able to capture and
predict the housing-demographic dynamics of the real-state market by simulating
the transitions of owners among price-based house layers. This model allows us
to determine which parameters are most effective to smoothen the severity of a
potential market crisis. The International Monetary Fund (IMF) has issued
severe warnings about the current real-state bubble in the United States, the
United Kingdom, Ireland, the Netherlands, Australia and Spain in the last
years. Madrid (Spain), in particular, is an extreme case of this bubble. It is,
therefore, an excellent test case to analyze housing dynamics in the context of
the empirical data provided by the Spanish National Institute of Statistics and
other sources of data. The model is able to predict the mean house occupancy,
and shows that i) the house market conditions in Madrid are unstable but not
critical; and ii) the regulation of the construction rate is more effective
than interest rate changes. Our results indicate that to accommodate the
construction rate to the total population of first-time buyers is the most
effective way to maintain the system near equilibrium conditions. In addition,
we show that to raise interest rates will heavily affect the poorest housing
bands of the population while the middle class layers remain nearly unaffected.


title: New angles on top quark decay to a charged Higgs Boson

abstract:
  Top quarks produced in pairs are predicted to experience spin correlations.
Due to the large ttbar statistics expected for the LHC, it should be possible
to search for new physics effects in angular variables sensitive to these
correlations. We investigate, for a general two-Higgs Doublet Model (2HDM), the
charged Higgs boson decay of the top quark through the channel $t\to bH^+\to
b\tau^+\nu_\tau$. Analytic results are presented on the spin analyzing
coefficients for this decay mode. We then explore in some detail the
correlation phenomenology in the Type II 2HDM. Finally we present a
hadron-level Monte Carlo analysis, illustrating distributions in azimuthal
angles which are sensitive to correlations in the transverse plane. These
observables are accessible also in the tau channel, and are therefore
particularly interesting for analyzing the $t\to bH^+$ decay.


title:
Backlund-Transformation-Related Recursion Operators: Application to the
  Self-Dual Yang-Mills Equation

abstract:
  By using the self-dual Yang-Mills (SDYM) equation as an example, we study a
method for relating symmetries and recursion operators of two partial
differential equations connected to each other by a non-auto-Backlund
transformation. We prove the Lie-algebra isomorphism between the symmetries of
the SDYM equation and those of the potential SDYM (PSDYM) equation, and we
describe the construction of the recursion operators for these two systems.
Using certain known aspects of the PSDYM symmetry algebra, we draw conclusions
regarding the Lie algebraic structure of the "potential symmetries" of the SDYM
equation.


title: Rational representations of $GL_2$

abstract:
  Let $F$ be an algebraically closed field of characteristic $p$. We fashion an
infinite dimensional basic algebra $\underleftarrow{\mathcal{C}}_p(F)$, with a
transparent combinatorial structure, which we expect to control the rational
representation theory of $GL_2(F)$.


title: Gate-induced interlayer asymmetry in ABA-stacked trilayer graphene

abstract:
  We calculate the electronic band structure of ABA-stacked trilayer graphene
in the presence of external gates, using a self-consistent Hartree
approximation to take account of screening. In the absence of a gate potential,
there are separate pairs of linear and parabolic bands at low energy. A gate
field perpendicular to the layers breaks mirror reflection symmetry with
respect to the central layer and hybridizes the linear and parabolic low-energy
bands, leaving a chiral Hamiltonian essentially different from that of
monolayer or bilayer graphene. Using the self-consistent Born approximation, we
find that the density of states and the minimal conductivity in the presence of
disorder generally increase as the gate field increases, in sharp contrast with
bilayer graphene.


title: Dehydrogenated polycyclic aromatic hydrocarbons and UV bump

abstract:
  Recent calculations have shown that the UV bump at about 217.5 nm in the
extinction curve can be explained by a complex mixture of PAHs in several
charge states. Other studies proposed that the carriers are a restricted
population made of neutral and singly-ionised dehydrogenated coronene molecules
(C24Hn, n less than 3), in line with models of the hydrogenation state of
interstellar PAHs predicting that medium-sized species are highly
dehydrogenated. To assess the observational consequences of the latter
hypothesis we have undertaken a systematic study of the electronic spectra of
dehydrogenated PAHs. We use our first results to see whether such spectra show
strong general trends upon dehydrogenation. We used state-of-the-art techniques
in the framework of the density functional theory (DFT) to obtain the
electronic ground-state geometries, and of the time- dependent DFT to evaluate
the electronic excited-state properties. We computed the absorption
cross-section of the species C24Hn (n=12,10,8,6,4,2,0) in their neutral and
cationic charge-states. Similar calculations were performed for other PAHs and
their fullydehydrogenated counterparts. pi electron energies are always found
to be strongly affected by dehydrogenation. In all cases we examined,
progressive dehydrogenation translates into a correspondingly progressive blue
shift of the main electronic transitions. In particular, the pi-pi* collective
resonance becomes broader and bluer with dehydrogenation. Its calculated energy
position is therefore predicted to fall in the gap between the UV bump and the
far-UV rise of the extinction curve. Since this effect appears to be
systematic, it poses a tight observational limit on the column density of
strongly dehydrogenated medium-sized PAHs.


title: On non-linear action of multiple M2-branes

abstract:
  A nonlinear SO(8) invariant BF type Lagrangian for describing the dynamics of
N M2-branes in flat spacetime has been proposed recently in the literature
which is an extension of the non-abelian DBI action of N D2-branes. This action
includes only terms with even number of the totally antisymmetric tensor
M^{IJK}. We argue that the action should contain terms with odd number of
M^{IJL} as well. We modify the action to include them.


title: Sudden extinction of a critical branching process in random environment

abstract:
  Let $T$ be the extinction moment of a critical branching process
$Z=(Z_{n},n\geq 0) $ in a random environment specified by iid probability
generating functions. We study the asymptotic behavior of the probability of
extinction of the process $Z$ at moment $n\to \infty$, and show that if the
logarithm of the (random) expectation of the offspring number belongs to the
domain of attraction of a non-gaussian stable law then the extinction occurs
owing to very unfavorable environment forcing the process, having at moment
$T-1$ exponentially large population, to die out. We also give an
interpretation of the obtained results in terms of random walks in random
environment.


title: Coupling from the photosphere to the chromosphere and the corona

abstract:
  The atmosphere of the Sun is characterized by a complex interplay of
competing physical processes: convection, radiation, conduction, and magnetic
fields. The most obvious imprint of the solar convection and its overshooting
in the low atmosphere is the granulation pattern. Beside this dominating scale
there is a more or less smooth distribution of spatial scales, both towards
smaller and larger scales, making the Sun essentially a multi-scale object.
Convection and overshooting give the photosphere its face but also act as
drivers for the layers above, namely the chromosphere and corona. The magnetic
field configuration effectively couples the atmospheric layers on a multitude
of spatial scales, for instance in the form of loops that are anchored in the
convection zone and continue through the atmosphere up into the chromosphere
and corona. The magnetic field is also an important structuring agent for the
small, granulation-size scales, although (hydrodynamic) shock waves also play
an important role -- especially in the internetwork atmosphere where mostly
weak fields prevail. Based on recent results from observations and numerical
simulations, we attempt to present a comprehensive picture of the atmosphere of
the quiet Sun as a highly intermittent and dynamic system.


title: Homotopy, homology, and $GL_2$

abstract:
  We define weak 2-categories of finite dimensional algebras with bimodules,
along with collections of operators $\mathbb{O}_{(c,x)}$ on these 2-categories.
We prove that special examples $\mathbb{O}_p$ of these operators control all
homological aspects of the rational representation theory of the algebraic
group $GL_2$, over a field of positive characteristic. We prove that when $x$
is a Rickard tilting complex, the operators $\mathbb{O}_{(c,x)}$ honour derived
equivalences, in a differential graded setting. We give a number of
representation theoretic corollaries, such as the existence of tight
$\mathbb{Z}_+$-gradings on Schur algebras $S(2,r)$, and the existence of braid
group actions on the derived categories of blocks of these Schur algebras.


title: Universal classes for algebraic groups

abstract:
  We exhibit cocycles representing certain classes in the rational cohomology
of of the general linear group with coefficients in the divided powers of a
Frobenius twist of the adjoint representation. These classes' existence was
anticipated by van der Kallen, and they intervene in the proof that reductive
linear algebraic groups have finitely generated cohomology algebras.


title:
New deep XMM-Newton observations to the west of the sigma Orionis
  cluster

abstract:
  Aims: The objective of this study is to determine the general X-ray
properties of the young stars in the external regions of the sigma Orionis
cluster (tau ~ 3 Ma, d ~ 385 pc) and yield constraints on the X-ray emission of
brown dwarfs. Methods: We carried out a careful analysis of public data taken
in an unexplored region to the west of the centre of the cluster with the three
EPIC cameras onboard the XMM-Newton mission. We looked for new X-ray young
stars among the 41 identified X-ray sources in the area with maximum likelihood
parameters L > 15 by cross-correlation with the USNO-B1, DENIS, and 2MASS
databases. Results: Based on colour-colour, colour-magnitude, and hardness
ratio diagrams, and previous spectroscopic, astrometric, and infrared-flux
excess information, we classified the optical/near-infrared counterparts of the
X-ray sources into: young stars (15), field stars (4), galaxies (19), and
sources of unknown nature (3). Most of the X-ray detections, including those of
nine young stars, are new. We derived the X-ray properties (e.g. temperatures,
metallicities, column densities) of the twelve young stars with the largest
signal-to-noise ratios. The X-ray parameters determined here are in well
agreement with those found in the cluster centre, where the stellar density is
higher. There is no relation between infrared excess and column density from
X-ray measurement in our data. We detected flaring events in two young stars of
the sample. One of them showed a very large (~ 30) relative increase in flux.
Both stars showed high coronal temperatures during the observation. Finally, we
determined upper limits to the flux of the young stars and bright brown dwarfs
not detected by our searching algorithm.


title: Sequestering in models of F-term uplifting

abstract:
  We discuss the nature of sequestering supersymmetry breaking sectors in a
certain class of moduli stabilization in supergravity/string models, where a
negative vacuum energy of the nonperturbative moduli potential is canceled by
dynamically generated F-terms. Two illustrating examples are shown to sketch
the issues around the supersymmetry breaking, flavors and sequestering within
such a framework.


title: CMB Anisotropy Induced by a Moving Straight Cosmic String

abstract:
  We showed that the part of strings could be detected by optical method is
only 20% from the total available amount of such objects, therefore the
gravitational lensing method has to be "completed" by CMB one. We found the
general structure of the CMB anisotropy generated by a cosmic string for simple
model of straight string moving with constant velocity. For strings with
deficit angle 1-2 arcsec the amplitude of generated anisotropy has to be 15-30
muK (the corresponding string linear density is (G mu) ~ 10^{-7} and energy is
GUT one, 10^{15} GeV). To use both radio and optical methods the deficit angle
has to be from 0.1 arcsec to 5-6 arcsec. If cosmic string can be detected by
optical method, the length of corresponding brightness spot of anisotropy has
to be no less than 100 degrees.


title: Vortex waves in trapped Bose-Einstein condensates

abstract:
  We have theoretically studied vortex waves of Bose-Einstein condensates in
elongated harmonic traps. Our focus is on the axisymmetric varicose waves and
helical Kelvin waves of singly quantized vortex lines. Growth and decay
dynamics of both types of vortex waves are discussed. We propose a method to
experimentally create these vortex waves on demand.


title: Determination of |Vud| from nuclear mirror transitions

abstract:
  The Vud element of the Cabibbo-Kobayashi-Maskawa quark mixing matrix has
traditionally been determined from the analysis of data in nuclear superallowed
0+ to 0+ transitions, neutron decay and pion beta decay. We show here that this
element can independently be determined from nuclear mirror transitions. The
extracted value, |Vud| = 0.9719 +- 0.0017, is at 1.2 combined standard
deviations from the value obtained in superallowed 0+ to 0+ transitions and has
a similar precision than the value obtained from neutron decay experiments. We
discuss some prospects to improve its precision through experiments in nuclear
mirror transitions.


title: Unparticle Phenomenology -- A Mini Review

abstract:
  We review some collider phenomenology of unparticle physics, including real
emissions and virtual exchanges of unparticle. Existing experimental
constraints from collider physics as well as astrophysics are briefly
discussed.


title:
Low-resolution spectroscopy and spectral energy distributions of
  selected sources towards sigma Orionis

abstract:
  Aims: We investigated in detail nine sources in the direction of the young
sigma Orionis cluster, which is considered a unique site for studying stellar
and substellar formation. The nine sources were selected because of some
peculiar properties, such as extremely red infrared colours or too strong
Halpha emission for their blue optical colours. Methods: We took high-quality,
low-resolution spectroscopy (R ~ 500) of the nine targets with ALFOSC at the
Nordic Optical Telescope. We also re-analyzed [24]-band photometry from
MIPS/Spitzer and compiled the best photometry available at the ViJHKs passbands
and the four IRAC/Spitzer channels for constructing accurate spectral energy
distributions covering from 0.55 to 24 mum. Results: The nine targets were
classified into: one Herbig Ae/Be star with a scatterer edge-on disc, two
G-type stars, one X-ray flaring, early-M, young star with chromospheric Halpha
emission, one very low-mass, accreting, young spectroscopic binary, two young
objects at the brown dwarf boundary with the characteristics of classical T
Tauri stars, and two emission-line galaxies, one undergoing star formation, and
another one whose spectral energy distribution is dominated by an active
galactic nucleus. Besides, we discover three infrared sources associated to
overdensities in a cold cloud in the cluster centre. Conclusions:
Low-resolution spectroscopy and spectral energy distributions are a vital tool
for measuring the physical properties and the evolution of young stars and
candidates in the sigma Orionis cluster.


title: Optical Spectroscopy in CoO: Phonons, Electric, and Magnetic Excitations

abstract:
  The reflectivity of single-crystalline CoO has been studied by optical
spectroscopy for wave numbers ranging from 100 to 28,000\wn and for
temperatures 8 $< T <$ 325 K\@. A splitting of the cubic IR-active phonon mode
on passing the antiferromagnetic phase transition at $T_N$ = 289 K has been
observed. At low temperatures the splitting amounts to 15.0\wn. In addition, we
studied the splitting of the cubic crystal field ground state of the Co$^{2+}$
ions due to spin-orbit coupling, a tetragonal crystal field, and exchange
interaction. Below $T_N$, magnetic dipole transitions between the
exchange-split levels are identified and the energy-level scheme can be well
described with a spin-orbit coupling $\lambda = 151.1\wn$, an exchange constant
$J = 17.5\wn$, and a tetragonal crystal-field parameter $D = -47.8\wn$. Already
in the paramagnetic state electric quadrupole transitions between the
spin-orbit split level have been observed. At high frequencies, two electronic
levels of the crystal-field-split $d$-manifold were identified at 8,000 and
18,500\wn.


title:
Emission vs Fermi coordinates: applications to relativistic positioning
  systems

abstract:
  A 4-dimensional relativistic positioning system for a general spacetime is
constructed by using the so called "emission coordinates". The results apply in
a small region around the world line of an accelerated observer carrying a
Fermi triad, as described by the Fermi metric. In the case of a Schwarzschild
spacetime modeling the gravitational field around the Earth and an observer at
rest at a fixed spacetime point, these coordinates realize a relativistic
positioning system alternative to the current GPS system. The latter is indeed
essentially conceived as Newtonian, so that it necessarily needs taking into
account at least the most important relativistic effects through Post-Newtonian
corrections to work properly. Previous results concerning emission coordinates
in flat spacetime are thus extended to this more general situation.
Furthermore, the mapping between spacetime coordinates and emission coordinates
is completely determined by means of the world function, which in the case of a
Fermi metric can be explicitly obtained.


title:
Distributions of Conductance and Shot Noise and Associated Phase
  Transitions

abstract:
  For a chaotic cavity with two indentical leads each supporting N channels, we
compute analytically, for large N, the full distribution of the conductance and
the shot noise power and show that in both cases there is a central Gaussian
region flanked on both sides by non-Gaussian tails. The distribution is weakly
singular at the junction of Gaussian and non-Gaussian regimes, a direct
consequence of two phase transitions in an associated Coulomb gas problem.


title:
A phase transition for non-intersecting Brownian motions, and the
  Painleve II equation

abstract:
  We consider n non-intersecting Brownian motions with two fixed starting
positions and two fixed ending positions in the large n limit. We show that in
case of 'large separation' between the endpoints, the particles are
asymptotically distributed in two separate groups, with no interaction between
them, as one would intuitively expect. We give a rigorous proof using the
Riemann-Hilbert formalism. In the case of 'critical separation' between the
endpoints we are led to a model Riemann-Hilbert problem associated to the
Hastings-McLeod solution of the Painleve II equation. We show that the Painleve
II equation also appears in the large n asymptotics of the recurrence
coefficients of the multiple Hermite polynomials that are associated with the
Riemann-Hilbert problem.


title:
Transverse-Mass Spectra in Heavy-Ion Collisions at energies E_{lab} =
  2--160 GeV/nucleon

abstract:
  Transverse-mass spectra of protons, pions and kaons produced in collisions of
heavy nuclei are analyzed within the model of 3-fluid dynamics. It was
demonstrated that this model consistently reproduces these spectra in wide
ranges of incident energies E_{lab}, from 4A GeV to 160A GeV, rapidity bins and
centralities of the collisions. In particular, the model describes the
"step-like" dependence of kaon inverse slopes on the incident energy. The key
point of this explanation is interplay of hydrodynamic expansion of the system
with its dynamical freeze-out.


title: Stochastic field equation for the canonical ensemble of a Bose gas

abstract:
  We present a novel norm preserving stochastic evolution equation for a Bose
field. Ensemble averages are quantum expectation values in the canonical
ensemble. This numerically very stable equation suppresses high-energy
fluctuations exponentially, preventing cutoff problems to occur. We present 3D
simulations for an ideal gas in various trapping potentials focussing on ground
state occupation numbers and spatial correlation functions for a wide range of
temperatures above and below the critical temperature. Although rigorously
valid for non-interacting Bosons only, we argue that weakly interacting Bose
gases may also be amenable to this approach, in the usual mean-field
approximation.


title: Photon and Graviton Mass Limits

abstract:
  Efforts to place limits on deviations from canonical formulations of
electromagnetism and gravity have probed length scales increasing dramatically
over time.Historically, these studies have passed through three stages: (1)
Testing the power in the inverse-square laws of Newton and Coulomb, (2) Seeking
a nonzero value for the rest mass of photon or graviton, (3) Considering more
degrees of freedom, allowing mass while preserving explicit gauge or
general-coordinate invariance. Since our previous review the lower limit on the
photon Compton wavelength has improved by four orders of magnitude, to about
one astronomical unit, and rapid current progress in astronomy makes further
advance likely. For gravity there have been vigorous debates about even the
concept of graviton rest mass. Meanwhile there are striking observations of
astronomical motions that do not fit Einstein gravity with visible sources.
"Cold dark matter" (slow, invisible classical particles) fits well at large
scales. "Modified Newtonian dynamics" provides the best phenomenology at
galactic scales. Satisfying this phenomenology is a requirement if dark matter,
perhaps as invisible classical fields, could be correct here too. "Dark energy"
{\it might} be explained by a graviton-mass-like effect, with associated
Compton wavelength comparable to the radius of the visible universe. We
summarize significant mass limits in a table.


title:
A comparative study of Dirac quasinormal modes of charged black holes in
  higher dimensions

abstract:
  In this work we study the Dirac quasinormal modes of higher dimensional
charged black holes. Higher dimensional Reissner-N\"{o}rdstrom type black holes
as well as charged black holes in Einstein Gauss-Bonnet theories are studied
for Fermionic perturbations using WKB method. A comparative study of the
quasinormal modes in the two different theories of gravity has been performed.
The beahviour of the frequencies with the variation of black hole parameters as
well as with the variation of spacetime dimensions are done. We also study the
large multipole number limit of the black hole potential in order to look for
an analytic expression for the frequencies.


title: Confinement and Non-perturbative Tachyons in Brane-Antibrane Systems

abstract:
  We present a worldvolume effective action suitable for the study of the
confined phase of a Dp-anti-Dp system at weak coupling. We identify the
mechanism by which the fundamental string arises from this action as a confined
electric flux string when the Dp and the anti-Dp annihilate. We construct an
explicit dual action, more suitable for the study of the strong coupling
regime, and show that it realizes a generalized Higgs-Stueckelberg phase for
the (relative) (p-2)-form field dual to the (overall) BI vector. This is the
mechanism put forward by Yi and collaborators based on duality arguments in
order to explain the breaking of the overall U(1) gauge group at strong
coupling. Indeed, in our dual description the Goldstone boson is a (p-3)-form
magnetically charged with respect to the overall BI vector field. This
indicates that the condensing tachyonic objects originate from open
D(p-2)-branes stretched between the brane and the anti-brane. Our results
provide an explicit realization of the breaking of the overall U(1) gauge group
perturbatively, in a way consistent with the duality symmetries of String
Theory.


title: Spin Polarization Effects in Micro Black Hole Evaporation

abstract:
  We consider the evaporation of rotating micro black holes produced in highly
energetic particle collisions, taking into account the polarization due to the
coupling between the spin of the emitted particles and the angular momentum of
the black hole. The effect of rotation shows up in the helicity dependent
angular distribution significantly. By using this effect, there is a
possibility to determine the axis of rotation for each black hole formed,
suggesting a way to improve the statistics. Deviation from thermal spectrum is
also a signature of rotation. This deviation is due to the fact that rapidly
rotating holes have an effective temperature $T_{\rm eff}$ significantly higher
than the Hawking temperature $T_H$. The deformation of the spectral shape
becomes evident only for very rapidly rotating cases. We show that, since the
spectrum follows a blackbody profile with an effective temperature, it is
difficult to determine both the number of extra-dimensions and the rotation
parameter from the energy spectrum alone. We argue that the helicity dependent
angular distribution may provide a way to resolve this degeneracy. We
illustrate the above results for the case of fermions.


title: Gravitational lensing by gravitational waves

abstract:
  Gravitational lensing by gravitational wave is considered. We notice that
although final and initial direction of photons coincide, displacement between
final and initial trajectories occurs. This displacement is calculated
analytically for the plane gravitational wave pulse. Estimations for
observations are discussed.


title:
Dynamics of Bianchi type I solutions of the Einstein equations with
  anisotropic matter

abstract:
  We analyze the global dynamics of Bianchi type I solutions of the Einstein
equations with anisotropic matter. The matter model is not specified explicitly
but only through a set of mild and physically motivated assumptions; thereby
our analysis covers matter models as different from each other as, e.g.,
collisionless matter, elastic matter and magnetic fields. The main result we
prove is the existence of an `anisotropy classification' for the asymptotic
behaviour of Bianchi type I cosmologies. The type of asymptotic behaviour of
generic solutions is determined by one single parameter that describes certain
properties of the anisotropic matter model under extreme conditions. The
anisotropy classification comprises the following types. The convergent type
\Aplus: Each solution converges to a Kasner solution as the singularity is
approached and each Kasner solution is a possible past asymptotic state. The
convergent types \Bplus and \Cplus: Each solution converges to a Kasner
solution as the singularity is approached; however, the set of Kasner solutions
that are possible past asymptotic states is restricted. The oscillatory type
\Dplus: Each solution oscillates between different Kasner solutions as the
singularity is approached. Furthermore, we investigate non-generic asymptotic
behaviour and the future asymptotic behaviour of solutions.


title: Calculation of the spectrum of the superheavy element Z=120

abstract:
  High-precision calculations of the energy levels of the superheavy element
Z=120 are presented. The relativistic Hartree-Fock and configuration
interaction techniques are employed. The correlations between core and valence
electrons are treated by means of the correlation potential method and
many-body perturbation theory. Similar calculations for barium and radium are
used to gauge the accuracy of the calculations and to improve the ab initio
results.


title: Non-Hermitian Polynomial Hybrid Monte Carlo

abstract:
  We report on a new variant of the hybrid Monte Carlo algorithm employing a
polynomial approximation of the inverse of the non-Hermitian Dirac-Wilson
operator. Our approximation relies on simple and stable recurrence relations of
complex Chebyshev polynomials. First performance figures are presented.


title: Rack-and-pinion effects in molecular rolling friction

abstract:
  Rolling lubrication with spherical molecules working as 'nanobearings' has
failed experimentally so far, without a full understanding of the physics
involved and of the reasons why. Past model simulations and common sense have
shown that molecules can only roll when they are not too closely packed to jam.
The same type of model simulations now shows in addition that molecular rolling
friction can develop deep minima once the molecule's peripheral 'pitch' can
match the substrate periodicity, much as ordinary cogwheels do in a
rack-and-pinion system. When the pinion-rack matching is bad, the driven
molecular rolling becomes discontinuous and noisy, whence energy is dissipated
and friction is large. This suggests experiments to be conducted by varying the
rack-and-pinion matching. That could be pursued not only by changing molecules
and substrates, but also by applying different sliding directions within the
same system, or by applying pressure, to change the effective matching.


title: Hybrid Quantum-Classical Monte-Carlo Study of a Molecule-Based Magnet

abstract:
  Using a Monte Carlo (MC) method, we study an effective model for the
Fe(II)Fe(III) bimetallic oxalates. Within a hybrid quantum-classical MC
algorithm, the Heisenberg S=2 and $S'=5/2$ spins on the Fe(II) and Fe(III)
sites are updated using a quantum MC loop while the Ising-like orbital angular
momenta on the Fe(II) sites are updated using a single-spin classical MC flip.
The effective field acting on the orbital angular momenta depends on the
quantum state of the system. We find that the mean-field phase diagram for the
model is surprisingly robust with respect to fluctuations. In particular, the
region displaying two compensation points shifts and shrinks but remains
finite.


title: Fermionic Casimir effect in de Sitter spacetime

abstract:
  The Casimir densities are investigated for a massive spinor field in de
Sitter spacetime with an arbitrary number of toroidally compactified spatial
dimensions. The vacuum expectation value of the energy-momentum tensor is
presented in the form of the sum of corresponding quantity in the
uncompactified de Sitter spacetime and the part induced by the non-trivial
topology. The latter is finite and the renormalization is needed for the first
part only. The asymptotic behavior of the topological term is investigated in
the early and late stages of the cosmological expansion. When the comoving
lengths of the compactified dimensions are much smaller than the de Sitter
curvature radius, to the leading order the topological part coincides with the
corresponding quantity for a massless fermionic field and is conformally
related to the corresponding flat spacetime result with the same topology. In
this limit the topological term dominates the uncompactified de Sitter part and
the back-reaction effects should be taken into account. In the opposite limit,
for a massive field the asymptotic behavior of the topological part is damping
oscillatory.


title:
Bifunctor cohomology and Cohomological finite generation for reductive
  groups

abstract:
  Let G be a reductive linear algebraic group over a field k. Let A be a
finitely generated commutative k-algebra on which G acts rationally by
k-algebra automorphisms. Invariant theory tells that the ring of invariants
A^G=H^0(G,A) is finitely generated. We show that in fact the full cohomology
ring H^*(G,A) is finitely generated. The proof is based on the strict
polynomial bifunctor cohomology classes constructed by the junior author. We
also continue the study of bifunctor cohomology of the divided powers of a
Frobenius twist of the adjoint representation.


title: Molecular rolling friction: the cogwheel model

abstract:
  With the help of a two-dimensional model we study rolling lubrication by
circular (2D fullerenes) molecules for a wide range of parameters. The
conditions under which microscopic rolling friction may be effective are
identified and related to the relative ingraining between substrate and
molecule, the latter behaving as a nanosized cogwheel.


title:
RNA matrix models with external interactions and their asymptotic
  behaviour

abstract:
  We study a matrix model of RNA in which an external perturbation acts on n
nucleotides of the polymer chain. The effect of the perturbation appears in the
exponential generating function of the partition function as a factor
$(1-\frac{n\alpha}{L})$ [where $\alpha$ is the ratio of strengths of the
original to the perturbed term and L is length of the chain]. The asymptotic
behaviour of the genus distribution functions for the extended matrix model are
analyzed numerically when (i) $n=L$ and (ii) $n=1$. In these matrix models of
RNA, as $n\alpha/L$ is increased from 0 to 1, it is found that the universality
of the number of diagrams $a_{L, g}$ at a fixed length L and genus g changes
from $3^{L}$ to $(3-\frac{n\alpha}{L})^{L}$ ($2^{L}$ when $n\alpha/L=1$) and
the asymptotic expression of the total number of diagrams $\cal N$ at a fixed
length L but independent of genus g, changes in the factor $\exp^{\sqrt{L}}$ to
$\exp^{(1-\frac{n\alpha}{L})\sqrt{L}}$ ($exp^{0}=1$ when $n\alpha/L=1$)


title: Entropy Concentration and the Empirical Coding Game

abstract:
  We give a characterization of Maximum Entropy/Minimum Relative Entropy
inference by providing two `strong entropy concentration' theorems. These
theorems unify and generalize Jaynes' `concentration phenomenon' and Van
Campenhout and Cover's `conditional limit theorem'. The theorems characterize
exactly in what sense a prior distribution Q conditioned on a given constraint,
and the distribution P, minimizing the relative entropy D(P ||Q) over all
distributions satisfying the constraint, are `close' to each other. We then
apply our theorems to establish the relationship between entropy concentration
and a game-theoretic characterization of Maximum Entropy Inference due to
Topsoe and others.

categories: cs.IT cs.LG math.IT math.ST stat.ME stat.TH


title: Kobayashi geodesics in A_g

abstract:
  We consider Kobayashi geodesics in the moduli space of abelian varieties A_g
that is, algebraic curves that are totally geodesic submanifolds for the
Kobayashi metric. We show that Kobayashi geodesics can be characterized as
those curves whose logarithmic tangent bundle splits as a subbundle of the
logarithmic tangent bundle of A_g.
  Both Shimura curves and Teichmueller curves are examples of Kobayashi
geodesics, but there are other examples. We show moreover that non-compact
Kobayashi geodesics always map to the locus of real multiplication and that the
Q-irreducibility of the induced variation of Hodge structures implies that they
are defined over a number field.


title: Moving and resizing of the screen objects

abstract:
  The shape and size of the objects, which we see on the screen, when the
application is running, are defined at the design time. By using some sort of
adaptive interface, developers give users a chance to resize these objects or
on rare occasion even change, but all these changes are predetermined by a
developer; user can't go out of the designer's scenario. Making each and all
elements moveable / resizable and giving users the full control of these
processes, changes the whole idea of applications; programs become user-driven
and significantly increase the effectiveness of users' work. This article is
about the instrument to turn any screen object into moveable / resizable.


title: Pfaffian and fragmented states at nu=5/2 in quantum Hall droplets

abstract:
  When a gas of electrons is confined to two dimensions, application of a
strong magnetic field may lead to startling phenomena such as emergence of
electron pairing. According to a theory this manifests itself as appearance of
the fractional quantum Hall effect with a quantized conductivity at an unusual
half-integer nu=5/2 Landau level filling. Here we show that similar electron
pairing may occur in quantum dots where the gas of electrons is trapped by
external electric potentials into small quantum Hall droplets. However, we also
find theoretical and experimental evidence that, depending on the shape of the
external potential, the paired electron state can break down, which leads to a
fragmentation of charge and spin densities into incompressible domains. The
fragmentation of the quantum Hall states could be an issue in the proposed
experiments that aim to probe for non-abelian quasi-particle characteristics of
the nu=5/2 quantum Hall state.


title: Gravitational radiospectrometer

abstract:
  Gravitational lensing is predicted by general relativity and is found in
observations. When a gravitating body is surrounded by a plasma, the lensing
angle depends on a frequency of the electromagnetic wave due to refraction
properties, and the dispersion properties of the light propagation in plasma.
The last effect leads to dependence, even in the uniform plasma, of the lensing
angle on the frequency, what resembles the properties of the refractive prism
spectrometer. The strongest action of this spectrometer is for the frequencies
slightly exceeding the plasma frequency, what corresponds to very long
radiowaves.


title: Separability of Tripartite Quantum Systems

abstract:
  We investigate the separability of arbitrary dimensional tripartite sys-
tems. By introducing a new operator related to transformations on the
subsystems a necessary condition for the separability of tripartite systems is
presented.


title: On Finite Width of Quark Gluon Plasma Bags

abstract:
  Within an exactly solvable model I discuss an influence of the medium
dependent finite width of QGP bags on their equation of state. It is shown that
inclusion of such a width allows one to naturally resolve two conceptual
problems of the QGP statistical description. On the basis of the proposed
simple kinetic model for a sequential decay of heavy QGP bags formed in high
energy elementary particle collisions it is argued that by measuring the energy
dependence of life time of these bags it is possible to distinguish the case of
critical point existence from the case of tricritical point.


title:
A simulation study comparing likelihood and non-likelihood approaches in
  analyzing overdispersed count data

abstract:
  Overdispersed count data are modelled with likelihood and non-likelihood
approaches. Likelihood approaches include the Poisson mixtures with three
distributions, the gamma, the lognormal, and the inverse Gaussian
distributions. Non-likelihood approaches include the robust sandwich estimator
and quasilikelihood. In this simulation study, overdispersed count data were
simulated under the Poisson mixtures with the gamma, the lognormal and the
inverse Gaussian distributions, then analyzed with the five likelihood and
non-likelihood approaches. Our results indicated that 1) when the count data
are mildly overdispersed, there are virtually no differences in type I error
rate, standard error of the main effect, and empirical power among the five
methods; 2) when the count data are very overdispersed, none of these five
approaches is robust to model misspecification as evaluated by type I error
rate, standard error of the main effect, and empirical power. This simulation
study raises caution on using non-likelihood method for analyzing very
overdispered count data because of likely higher type I error and inappropriate
power levels. Unlike non-likelihood approaches, likelihood approaches allow for
statistical tests based on likelihood ratios and for checking model fit and
provide basis for power and sample size calculations. When likelihood
approaches are used, we suggest comparing likelihood values to select the
appropriate parametric method for analyzing very overdispersed count data.


title: Time-delayed feedback in neurosystems

abstract:
  The influence of time delay in systems of two coupled excitable neurons is
studied in the framework of the FitzHugh-Nagumo model. Time-delay can occur in
the coupling between neurons or in a self-feedback loop. The stochastic
synchronization of instantaneously coupled neurons under the influence of white
noise can be deliberately controlled by local time-delayed feedback. By
appropriate choice of the delay time synchronization can be either enhanced or
suppressed. In delay-coupled neurons, antiphase oscillations can be induced for
sufficiently large delay and coupling strength. The additional application of
time-delayed self-feedback leads to complex scenarios of synchronized in-phase
or antiphase oscillations, bursting patterns, or amplitude death.


title: Flares in Gamma Ray Bursts

abstract:
  The flare activity that is observed in GRBs soon after the prompt emission
with the XRT (0.3-10 KeV) instrument on board of the Swift satellite is leading
to important clues in relation to the physical characteristics of the mechanism
generating the emission of energy in Gamma Ray Bursts. We will briefly refer to
the results obtained with the recent analysis and and discuss the preliminary
results we obtained with a new larger sample of GRBs [limited to early flares]
based on fitting of the flares using the Norris 2005 profile. We find, in
agreement with previous results, that XRT flares follow the main
characteristics observed in Norris 2005 for the prompt emission spikes. The
estimate of the flare energy for the subsample with redshift is rather robust
and an attempt is made, using the redshisft sample, to estimate how the energy
emitted in flares depends on time. We used a $H_0=70 km/s/Mpc$,
$\Omega_\Lambda=0.7$, $\Omega_m=0.3$ cosmology.


title:
On the frequentist coverage of Bayesian credible intervals for lower
  bounded means

abstract:
  For estimating a lower bounded location or mean parameter for a symmetric and
logconcave density, we investigate the frequentist performance of the
$100(1-\alpha)%$ Bayesian HPD credible set associated with priors which are
truncations of flat priors onto the restricted parameter space. Various new
properties are obtained. Namely, we identify precisely where the minimum
coverage is obtained and we show that this minimum coverage is bounded between
$1-\frac{3\alpha}{2}$ and $1-\frac{3\alpha}{2}+\frac{\alpha^2}{1+\alpha}$; with
the lower bound $1-\frac{3\alpha}{2}$ improving (for $\alpha \leq 1/3$) on the
previously established ([9]; [8]) lower bound $\frac{1-\alpha}{1+\alpha}$.
Several illustrative examples are given.


title: Bulk photonic metamaterial with hyperbolic dispersion

abstract:
  In this work, we demonstrate a self-standing bulk three-dimensional
metamaterial based on the network of silver nanowires in an alumina membrane.
This constitutes an anisotropic effective medium with hyperbolic dispersion,
which can be used in sub-diffraction imaging or optical cloaks. Highly
anisotropic dielectric constants of the material range from positive to
negative, and the transmitted laser beam shifts both toward the normal to the
surface, as in regular dielectrics, and off the normal, as in anisotropic
dielectrics with the refraction index smaller than one. The designed photonic
metamaterial is the thickest reported in the literature, both in terms of its
physical size 1cm x 1cm x 51 mm, and the number of vacuum wavelengths, N=61 at
l=0.84 mm.


title:
Galaxy mergers at high resolution: From elliptical galaxies to tidal
  dwarfs and globular clusters

abstract:
  Numerical simulations of galaxy mergers are a powerful tool to study these
fundamental events in the hierarchical built-up of galaxies. Recent progress
have been made owing to improved modeling, increased resolution and large
statistical samples. We present here the highest-resolution models of mergers
performed so far. The formation of a variety of substructures ranging from
kinematically decoupled cores to globular-like clusters is directly resolved.
In a resolution study, we show that the large-scale structure of
elliptical-like merger remnants can be affected by the resolution, and a too
modest resolution may affect the numerical predictions on the properties of
major merger remnants: understanding precisely which kind of event or
succession of events has formed the various types of elliptical galaxies
remains an open challenge.


title: Flat deformation theorem and symmetries in spacetime

abstract:
  The \emph{flat deformation theorem} states that given a semi-Riemannian
analytic metric $g$ on a manifold, locally there always exists a two-form $F$,
a scalar function $c$, and an arbitrarily prescribed scalar constraint
depending on the point $x$ of the manifold and on $F$ and $c$, say $\Psi (c, F,
x)=0$, such that the \emph{deformed metric} $\eta = cg -\epsilon F^2$ is
semi-Riemannian and flat. In this paper we first show that the above result
implies that every (Lorentzian analytic) metric $g$ may be written in the
\emph{extended Kerr-Schild form}, namely $\eta_{ab} := a g_{ab} - 2 b k_{(a}
l_{b)}$ where $\eta$ is flat and $k_a, l_a$ are two null covectors such that
$k_a l^a= -1$; next we show how the symmetries of $g$ are connected to those of
$\eta$, more precisely; we show that if the original metric $g$ admits a
Conformal Killing vector (including Killing vectors and homotheties), then the
deformation may be carried out in a way such that the flat deformed metric
$\eta$ `inherits' that symmetry.


title:
On the role of the nonlocal Hartree-Fock exchange in ab initio quantum
  transport: Hydrogen in Platinum nanocontacts revisited

abstract:
  We propose a practical way to overcome the ubiquitous problem of the
overestimation of the zero-bias and zero-temperature conductance, which is
associated to the use of local approximations to the exchange-correlation
functional in Density-Functional Theory when applied to quantum transport. This
is done through partial substitution of the local exchange term in the
functional by the nonlocal Hartree-Fock exchange. As a non-trivial example of
this effect we revisit the smallest molecular bridge studied so far: a Hydrogen
molecule placed in between Platinum nanocontacts. When applied to this system
the value of the conductance diminishes as compared to the local-exchange-only
value, which is in close agreement with results predicted from Time-Dependent
Current-Density-Functional Theory. Our results issue a warning message on
recent claims of perfect transparency of a Hydrogen molecule in Platinum
nanocontacts.


title: Avoided level crossing spectroscopy with dressed matter waves

abstract:
  We devise a method for probing resonances of macroscopic matter waves in
shaken optical lattices by monitoring their response to slow parameter changes,
and show that such resonances can be disabled by particular choices of the
driving amplitude. The theoretical analysis of this scheme reveals far-reaching
analogies between dressed atoms and time-periodically forced matter waves.


title: New properties of z-scaling: flavor independence and saturation at low z

abstract:
  Experimental data on inclusive cross sections of particles produced in high
energy proton-(anti)proton collisions at ISR, RHIC, and Tevatron are analyzed
in the framework of $z$-scaling. New features of the scaling function $\psi(z)$
are established. These are flavor independence of $\psi(z)$ including particles
with heavy flavor content and saturation at low $z$. The flavor independence
means that the shape of the scaling function $\psi(z)$ is the same for
different hadron species. The saturation corresponds to flattening of $\psi(z)$
for $z<0.1$. Relations of model parameters used in data $z$-presentation with
some thermodynamical quantities (entropy, specific heat, temperature) are
discussed. It is shown that behavior of the particle spectra at low $z$ is
controlled by a parameter $c$ interpreted as a specific heat of the created
medium associated with production of the inclusive particle. The saturation
regime of $\psi(z)$ observed at low $z$ is assumed to be preferable in
searching for phase transitions of hadron matter and for study of
non-perturbative QCD in high energy proton-(anti)proton collisions at U70,
RHIC, Tevatron, and LHC.


title: Optical properties of graphene: the Fermi liquid approach

abstract:
  Optical properties of two-dimensional massless Dirac fermions are considered
by the formalism of pseudospin precession equations which provides an easy and
natural semiphenomenological way to include correlation effects. It is shown
that the latter are negligible, with the only assumption that the system under
consideration is normal Fermi liquid. This result probably explains recent
experimental data on the universal optical conductivity of graphene (Nair R. R.
et al, Science 320 (2008) 1308).


title:
Hydrodynamic correlations in the translocation of biopolymer through a
  nanopore: theory and multiscale simulations

abstract:
  We investigate the process of biopolymer translocation through a narrow pore
using a multiscale approach which explicitly accounts for the hydrodynamic
interactions of the molecule with the surrounding solvent. The simulations
confirm that the coupling of the correlated molecular motion to hydrodynamics
results in significant acceleration of the translocation process. Based on
these results, we construct a phenomenological model which incorporates the
statistical and dynamical features of the translocation process and predicts a
power law dependence of the translocation time on the polymer length with an
exponent $\alpha$ $\approx 1.2$. The actual value of the exponent from the
simulations is $\alpha = 1.28 \pm 0.01$, which is in excellent agreement with
experimental measurements of DNA translocation through a nanopore, and is not
sensitive to the choice of parameters in the simulation. The mechanism behind
the emergence of such a robust exponent is related to the interplay between the
longitudinal and transversal dynamics of both translocated and untranslocated
segments. The connection to the macroscopic picture involves separating the
contributions from the blob shrinking and shifting processes, which are both
essential to the translocation dynamics.


title: String Theory: A Framework for Quantum Gravity and Various Applications

abstract:
  In this semi-technical review we discuss string theory (and all that goes by
that name) as a framework for a quantum theory of gravity. This is a new
paradigm in theoretical physics that goes beyond relativistic quantum field
theory. We provide concrete evidence for this proposal. It leads to the
resolution of the ultra-violet catastrophe of Einstein's theory of general
relativity and an explanation of the Bekenstein-Hawking entropy (of a class of
black holes) in terms of Boltzmann's formula for entropy in statistical
mechanics. We discuss `the holographic principle' and its precise and
consequential formulation in the AdS/CFT correspondence of Maldacena. One
consequence of this correspondence is the ability to do strong coupling
calculations in SU(N) gauge theories in terms of semi-classical gravity. In
particular, we indicate a connection between dissipative fluid dynamics and the
dynamics of black hole horizons. We end with a discussion of elementary
particle physics and cosmology in the framework of string theory. We do not
cover all aspects of string theory and its applications to diverse areas of
physics and mathematics, but follow a few paths in a vast landscape of ideas.
(This article has been prepared for the TWAS Silver Jubilee)


title: Two Jupiter-Mass Planets Orbiting HD 154672 and HD 205739

abstract:
  We report the detection of the first two planets from the N2K Doppler planet
search program at the Magellan telescopes. The first planet has a mass of M sin
i = 4.96 M_Jup and is orbiting the G3 IV star HD154672 with an orbital period
of 163.9 days. The second planet is orbiting the F7 V star HD205739 with an
orbital period of 279.8 days and has a mass of M sin i = 1.37 M_Jup. Both
planets are in eccentric orbits, with eccentricities e = 0.61 and e = 0.27,
respectively. Both stars are metal rich and appear to be chromospherically
inactive, based on inspection of their Ca II H and K lines. Finally, the best
Keplerian model fit to HD205739b shows a trend of 0.0649 m/s/day, suggesting
the presence of an additional outer body in that system.


title: Polyakov D1 Brane Action On the Light-Front

abstract:
  Conformally gauge-fixed Polyakov D1 brane action is seen to be a constrained
sys tem in the sense of Dirac when it is considered on the light-front in
contrast t o the case when it is consdired in the instant-form. The model is
quantized usin g the standard constraint quantization techniques on the
light-front.


title:
High-SNR Analysis of Outage-Limited Communications with Bursty and
  Delay-Limited Information

abstract:
  This work analyzes the high-SNR asymptotic error performance of
outage-limited communications with fading, where the number of bits that arrive
at the transmitter during any time slot is random but the delivery of bits at
the receiver must adhere to a strict delay limitation. Specifically, bit errors
are caused by erroneous decoding at the receiver or violation of the strict
delay constraint. Under certain scaling of the statistics of the bit-arrival
process with SNR, this paper shows that the optimal decay behavior of the
asymptotic total probability of bit error depends on how fast the burstiness of
the source scales down with SNR. If the source burstiness scales down too
slowly, the total probability of error is asymptotically dominated by
delay-violation events. On the other hand, if the source burstiness scales down
too quickly, the total probability of error is asymptotically dominated by
channel-error events. However, at the proper scaling, where the burstiness
scales linearly with 1/sqrt(log SNR) and at the optimal coding duration and
transmission rate, the occurrences of channel errors and delay-violation errors
are asymptotically balanced. In this latter case, the optimal exponent of the
total probability of error reveals a tradeoff that addresses the question of
how much of the allowable time and rate should be used for gaining reliability
over the channel and how much for accommodating the burstiness with delay
constraints.


title:
Patterns in high-frequency FX data: Discovery of 12 empirical scaling
  laws

abstract:
  We have discovered 12 independent new empirical scaling laws in foreign
exchange data-series that hold for close to three orders of magnitude and
across 13 currency exchange rates. Our statistical analysis crucially depends
on an event-based approach that measures the relationship between different
types of events. The scaling laws give an accurate estimation of the length of
the price-curve coastline, which turns out to be surprisingly long. The new
laws substantially extend the catalogue of stylised facts and sharply constrain
the space of possible theoretical explanations of the market mechanisms.


title: CP violation in neutrino oscillations and new physics

abstract:
  We consider future experiments to detect CP violation in neutrino
oscillations and discuss how to test that all asymmetries are indeed described
in terms of the single leptonic Jarlskog invariant as predicted in the absence
of new physics effects.


title: Vector Schwinger Model with a Photon Mass Term on the Light-Front

abstract:
  Vector Schwinger model with a mass term for the photon, describing 2D
electrodyn amics with massless fermions, studied by us recently, represents a
new class of models. This theory becomes gauge-invariant when studied on the
light-front. Thi s is in contrast to the instant-form theory which is
gauge-noninvariant. We quan tize this theory on the light-front.


title: On Unique Decodability

abstract:
  In this paper we propose a revisitation of the topic of unique decodability
and of some fundamental theorems of lossless coding. It is widely believed
that, for any discrete source X, every "uniquely decodable" block code
satisfies E[l(X_1 X_2 ... X_n)]>= H(X_1,X_2,...,X_n), where X_1, X_2,...,X_n
are the first n symbols of the source, E[l(X_1 X_2 ... X_n)] is the expected
length of the code for those symbols and H(X_1,X_2,...,X_n) is their joint
entropy. We show that, for certain sources with memory, the above inequality
only holds when a limiting definition of "uniquely decodable code" is
considered. In particular, the above inequality is usually assumed to hold for
any "practical code" due to a debatable application of McMillan's theorem to
sources with memory. We thus propose a clarification of the topic, also
providing an extended version of McMillan's theorem to be used for Markovian
sources.


title: A percolation model for slow dynamics in glass-forming materials

abstract:
  We identify a link between the glass transition and percolation of mobile
regions in configuration space. We find that many hallmarks of glassy dynamics,
for example stretched-exponential response functions and a diverging structural
relaxation time, are consequences of the critical properties of mean-field
percolation. Specific predictions of the percolation model include the range of
possible stretching exponents $1/3 \leq \beta \leq 1$ and the functional
dependence of the structural relaxation time $\tau_\alpha$ and exponent $\beta$
on temperature, density, and wave number.


title: Homogenization with large spatial random potential

abstract:
  We consider the homogenization of parabolic equations with large
spatially-dependent potentials modeled as Gaussian random fields. We derive the
homogenized equations in the limit of vanishing correlation length of the
random potential. We characterize the leading effect in the random fluctuations
and show that their spatial moments converge in law to Gaussian random
variables. Both results hold for sufficiently small times and in sufficiently
large spatial dimensions $d\geq\m$, where $\m$ is the order of the spatial
pseudo-differential operator in the parabolic equation. In dimension $d<\m$,
the solution to the parabolic equation is shown to converge to the
(non-deterministic) solution of a stochastic equation in the companion paper
[2]. The results are then extended to cover the case of long range random
potentials, which generate larger, but still asymptotically Gaussian, random
fluctuations.


title: Principal Chiral Model on Superspheres

abstract:
  We investigate the spectrum of the principal chiral model (PCM) on
odd-dimensional superspheres as a function of the curvature radius R. For
volume-filling branes on S^{3|2}, we compute the exact boundary spectrum as a
function of R. The extension to higher dimensional superspheres is discussed,
but not carried out in detail. Our results provide very convincing evidence in
favor of the strong-weak coupling duality between supersphere PCMs and
OSP(2S+2|2S) Gross-Neveu models that was recently conjectured by Candu and
Saleur in arXiv:0801.0444.

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


title: Convergence to SPDEs in Stratonovich form

abstract:
  We consider the perturbation of parabolic operators of the form
  $\partial_t+P(x,D)$ by large-amplitude highly oscillatory spatially dependent
potentials modeled as Gaussian random fields. The amplitude of the potential is
chosen so that the solution to the random equation is affected by the
randomness at the leading order. We show that, when the dimension is smaller
than the order of the elliptic pseudo-differential operator $P(x,D)$, the
perturbed parabolic equation admits a solution given by a Duhamel expansion.
Moreover, as the correlation length of the potential vanishes, we show that the
latter solution converges in distribution to the solution of a stochastic
parabolic equation with a multiplicative term that should be interpreted in the
Stratonovich sense. The theory of mild solutions for such stochastic partial
differential equations is developed. The behavior described above should be
contrasted to the case of dimensions that are larger than or equal to the order
of the elliptic pseudo-differential operator $P(x,D)$. In the latter case, the
solution to the random equation converges strongly to the solution of a
homogenized (deterministic) parabolic equation as is shown in the companion
paper [2]. The stochastic model is therefore valid only for sufficiently small
space dimensions in this class of parabolic problems.


title:
On a $p$-adic extension of the Jacquet-Langlands correspondence to
  weight 1

abstract:
  We consider a novel version of the classical Jacquet-Langlands
{correspondence}, explore a $p$-adic extension of the Jacquet-Langlands
correspondence, and as an explicit example we find an overconvergent
automorphic form of weight~1 which corresponds to a classical modular form of
weight~1, using both experimental and theoretical methods.


title: Multiple Quantum NMR and Entanglement Dynamics in Dipolar Coupling Spin

abstract:
  We investigate numerically the time dependence of the multiple quantum
coherences and entanglement in linear chains up to nine nuclear spins of 1/2
coupled by the dipole-dipole interactions. Two models are considered: (1) a
spin chain with nearest-neighbor dipole -dipole interactions; (2) a more
realistic model with interactions between all spins. It is shown that the
entangled states appear between remote particles which do not interact directly
(model 1), while the interaction between all spins (model 2) not always results
in entanglement between remote spins.


title: New Results from the H1 Collaboration

abstract:
  After more than 15 years, the operation of the world's unique electron-proton
collider HERA ended in June 2007. The data collected by the H1 experiment
correspond to a total integrated luminosity of about 0.5 fb$^{-1}$. In 2007
dedicated runs were taken at lower proton beam energies to measure the
longitudinal proton structure function $F_L$. In this talk new results, many of
them exploiting data taken after the HERA upgrade in the year 2000, and the
first measurement of $F_L$ are presented.


title: Superperturbation solver for quantum impurity models

abstract:
  We present a very efficient solver for the general Anderson impurity problem.
It is based on the perturbation around a solution obtained from exact
diagonalization using a small number of bath sites. We formulate a perturbation
theory which is valid for both weak and strong coupling and interpolates
between these limits. Good agreement with numerically exact quantum Monte-Carlo
results is found for a single bath site over a wide range of parameters. In
particular, the Kondo resonance in the intermediate coupling regime is well
reproduced for a single bath site and the lowest order correction. The method
is particularly suited for low temperatures and alleviates analytical
continuation of imaginary time data due to the absence of statistical noise
compared to quantum Monte-Carlo impurity solvers.


title: Terwilliger Algebras of Wreath Powers of One-Class Association Schemes

abstract:
  In this paper, we study the subconstituent algebras, also called as
Terwilliger algebras, of association schemes that are obtained as the wreath
product of one-class association schemes $K_n=H(1, n)$ for $n\ge 2$. We find
that the $d$-class association scheme $K_{n_{1}}\wr K_{n_{2}} \wr ... \wr
K_{n_{d}}$ formed by taking the wreath product of $K_{n_{i}}$ has the
triple-regularity property. We determine the dimension of the Terwilliger
algebra for the association scheme $K_{n_{1}}\wr K_{n_{2}}\wr ... \wr K_
{n_{d}}$. We give a description of the structure of the Terwilliger algebra for
the wreath power $(K_n)^{\wr d}$ for $n \geq 2$ by studying its irreducible
modules. In particular, we show that the Terwilliger algebra of $(K_n)^{\wr d}$
is isomorphic to $M_{d+1}(\mathbb{C})\oplus M_1(\mathbb{C})^{\oplus
\frac12d(d+1)}$ for $n\ge3$, and $M_{d+1}(\mathbb{C})\oplus
M_1(\mathbb{C})^{\oplus \frac12d(d-1)}$ for $n=2$.


title: An impossibility result for process discrimination

abstract:
  Two series of binary observations $x_1,x_1,...$ and $y_1,y_2,...$ are
presented: at each time $n\in\N$ we are given $x_n$ and $y_n$. It is assumed
that the sequences are generated independently of each other by two
B-processes. We are interested in the question of whether the sequences
represent a typical realization of two different processes or of the same one.
We demonstrate that this is impossible to decide, in the sense that every
discrimination procedure is bound to err with non-negligible frequency when
presented with sequences from some B-processes. This contrasts earlier positive
results on B-processes, in particular those showing that there are consistent
$\bar d$-distance estimates for this class of processes.


title: Matter-wave cavity gravimeter

abstract:
  We propose a gravimeter based on a matter-wave resonant cavity loaded with a
Bose-Einstein condensate and closed with a sequence of periodic Raman pulses.
The gravimeter sensitivity increases quickly with the number of cycles
experienced by the condensate inside the cavity. The matter wave is refocused
thanks to a spherical wave-front of the Raman pulses. This provides a
transverse confinement of the condensate which is discussed in terms of a
stability analysis. We develop the analogy of this device with a resonator in
momentum space for matter waves.

categories: physics.atom-ph cond-mat.other physics.optics quant-ph


title:
Statistical anisotropy of the curvature perturbation from vector field
  perturbations

abstract:
  The \delta N formula for the primordial curvature perturbation \zeta is
extended to include vector as well as scalar fields. Formulas for the
tree-level contributions to the spectrum and bispectrum of \zeta are given,
exhibiting statistical anisotropy. The one-loop contribution to the spectrum of
\zeta is also worked out. We then consider the generation of vector field
perturbations from the vacuum, including the longitudinal component that will
be present if there is no gauge invariance. Finally, the \delta N formula is
applied to the vector curvaton and vector inflation models with the tensor
perturbation also evaluated in the latter case.


title:
Groundstatable fermionic wavefunctions and their associated many-body
  Hamiltonians

abstract:
  In the vast majority of many-body problems, it is the kinetic energy part of
the Hamiltonian that is best known microscopically, and it is the detailed form
of the interactions between the particles, the potential energy term, that is
harder to determine from first principles. An example is the case of high
temperature superconductors: while a tight-binding model captures the kinetic
term, it is not clear that there is superconductivity with only an onsite
repulsion and, thus, that the problem is accurately described by the Hubbard
model alone. Here we pose the question of whether, once the kinetic energy is
fixed, a candidate ground state is {\it groundstatable or not}. The easiness to
answer this question is strongly related to the presence or the absence of a
sign problem in the system. When groundstatability is satisfied, it is simple
to obtain the potential energy that will lead to such a ground state. As a
concrete case study, we apply these ideas to different fermionic wavefunctions
with superconductive or spin-density wave correlations and we also study the
influence of Jastrow factors. The kinetic energy considered is a simple next
nearest neighbor hopping term.


title:
The Wide-Field X and Gamma-Ray Telescope ECLAIRs aboard the Gamma-Ray
  Burst Multi-Wavelength Space Mission SVOM

abstract:
  The X and Gamma-ray telescope ECLAIRs is foreseen to be launched on a low
Earth orbit (h=630 km, i=30 degrees) aboard the SVOM satellite (Space-based
multi-band astronomical Variable Objects Monitor), a French-Chinese mission
with Italian contribution. Observations are expected to start in 2013. It has
been designed to detect and localize Gamma-Ray Bursts (GRBs) or persistent
sources of the sky, thanks to its wide field of view (about 2 sr) and its
remarkable sensitivity in the 4-250 keV energy range, with enhanced imaging
sensitivity in the 4-70 keV energy band. These characteristics are well suited
to detect highly redshifted GRBs, and consequently to provide fast and accurate
triggers to other onboard or ground-based instruments able to follow-up the
detected events in a very short time from the optical wavelength bands up to
the few MeV Gamma-Ray domain.


title:
A Full Year's Chandra Exposure on SDSS Quasars from the Chandra
  Multiwavelength Project

abstract:
  We study the spectral energy distributions and evolution of a large sample of
optically selected quasars from the Sloan Digital Sky Survey (SDSS) that were
observed in 323 Chandra images analyzed by the Chandra Multiwavelength Project
(ChaMP). Our highest-confidence matched sample includes 1135 X-ray detected
quasars in the redshift range 0.2<z<5.4, representing some 36Msec of effective
exposure. Spectroscopic redshifts are available for about 1/3 of the detected
sample; elsewhere, redshifts are estimated photometrically. With 56 z>3 QSOs
detected, we find no evidence for evolution out to z~5 for either the X-ray
photon index Gamma or for the ratio of optical/UV to X-ray flux alpha_ox. About
10% of detected QSOs are obscured (Nh>1E22), but the fraction might reach ~1/3
if most non-detections are absorbed. We confirm a significant correlation
between alpha_ox and optical luminosity, but it flattens or disappears for
fainter AGN alone. Gamma hardens significantly both towards higher X-ray
luminosity, and for relatively X-ray loud quasars. These trends may represent a
relative increase in non-thermal X-ray emission, and our findings thereby
strengthen analogies between Galactic black hole binaries and AGN.


title: Matrix reduction and Lagrangian submodules

abstract:
  This paper deals with three technical ingredients of geometry for quantum
information. Firstly, we give an algorithm to obtain diagonal basis matrices
for submodules of the Z_{d}-module Z_{d}^{n} and we describe the suitable
computational basis. This algorithm is set along with the mathematical
properties and tools that are needed for symplectic diagonalisation. Secondly,
with only symplectic computational bases allowed, we get an explicit
description of the Lagrangian submodules of Z_{d}^{2n}. Thirdly, we introduce
the notion of a fringe of a Gram matrix and provide an explicit algorithm using
it in order to obtain a diagonal basis matrix with respect to a symplectic
computational basis whenever possible. If it is possible, we call the
corresponding submodule nearly symplectic. We also give an algebraic property
in order to single out symplectic submodules from nearly symplectic ones.


title: On the Schrodinger equation outside strictly convex obstacles

abstract:
  We prove sharp Strichartz estimates for the semi-classical Schrodinger
equation on a compact manifold with smooth, strictly geodesically concave
boundary. We deduce sharp (classical) Strichartz estimates for the Schrodinger
equation outside a strictly convex obstacle, local existence for the
H^1-critical (quintic) Schrodinger equation and scattering for the sub-critical
Schrodinger equation in 3D.


title:
A Novel Proportional Fairness Criterion for Throughput Allocation in
  Multirate IEEE 802.11

abstract:
  This paper focuses on multirate IEEE 802.11 Wireless LAN employing the
mandatory Distributed Coordination Function (DCF) option. Its aim is threefold.
Upon starting from the multi-dimensional Markovian state transition model
proposed by Malone \textit{et.al.} for characterizing the behavior of the IEEE
802.11 protocol at the Medium Access Control layer, it presents an extension
accounting for packet transmission failures due to channel errors. Second, it
establishes the conditions under which a network constituted by $N$ stations,
each station transmitting with its own bit rate, $R^{(s)}_d$, and packet rate,
$\lambda_s$, can be assumed loaded. Finally, it proposes a modified
Proportional Fairness (PF) criterion, suitable for mitigating the \textit{rate
anomaly} problem of multirate loaded IEEE 802.11 Wireless LANs, employing the
mandatory DCF option. Compared to the widely adopted assumption of saturated
network, the proposed fairness criterion can be applied to general loaded
networks.
  The throughput allocation resulting from the proposed algorithm is able to
greatly increase the aggregate throughput of the DCF, while ensuring fairness
levels among the stations of the same order as the ones guaranteed by the
classical PF criterion.
  Simulation results are presented for some sample scenarios, confirming the
effectiveness of the proposed criterion for optimized throughput allocation.


title: Heavy Ion Physics at the LHC

abstract:
  The first Pb-Pb collisions at the LHC are little more than a year away. This
paper discusses some of the exciting measurements which the experiments will be
able to perform in the very first run, even with modest luminosity, and gives a
very short overview of some of the most interesting ones attainable with more
extended runs. The dedicated Heavy-Ion experiment ALICE, but also ATLAS and
CMS, experiments optimized for p-p collisions, are ready and eager to make best
use of the nuclear beams in the LHC as soon as they will be available. The main
specificities of the three detectors for Heavy-Ion collisions will also be
briefly addressed in this paper. I will try to show that already the first
results obtainable with Heavy-Ion beams at the LHC will qualify it as a
discovery machine, capable to provide fundamental new insight to our knowledge
of high-density QCD matter.


title:
Target Location by DNA-Binding Proteins: Effects of Roadblocks and DNA
  Looping

abstract:
  The model of facilitated diffusion describes how DNA-binding proteins, such
as transcription factors (TFs), find their chromosomal targets by combining 3D
diffusion through the cytoplasm and 1D sliding along nonspecific DNA sequences.
The redundant 1D diffusion near the specific binding site extends the target
size and facilitates target location. While this model successfully predicts
the kinetics measured in test tubes, it has not been extended to account for
the highly crowded environment in living cells. Here, we investigate the effect
of other DNA-binding proteins that partially occupy the bacterial chromosome.
We show how they would slow down the search process, mainly through restricted
sliding near the target. This implies that increasing the overall DNA-binding
protein concentration would have a marginal effect in reducing the search time,
because any additional proteins would restrict the search process for each
other. While the presence of other proteins prevents sliding from the flanking
DNA, DNA looping provides an alternative path to transfer from neighboring
sites to the target efficiently. We propose that, when looping is faster than
the initial search process, the auxiliary binding sites further extend the
effective target region and therefore facilitate the target location.


title:
Reconstruction of non-classical cavity field states with snapshots of
  their decoherence

abstract:
  The state of a microscopic system encodes its complete quantum description,
from which the probabilities of all measurement outcomes are inferred. Being a
statistical concept, the state cannot be obtained from a single system
realization. It can be reconstructed from an ensemble of copies, by performing
measurements on different realizations. Reconstructing the state of a set of
trapped particles shielded from their environment is an important step for the
investigation of the quantum to classical boundary. While trapped atom state
reconstructions have been achieved, it is challenging to perform similar
experiments with trapped photons which require cavities storing light for very
long times. Here, we report the complete reconstruction and pictorial
representation of a variety of radiation states trapped in a cavity in which
several photons survive long enough to be repeatedly measured. Information is
extracted from the field by atoms crossing the cavity one by one. We exhibit a
gallery of pictures featuring coherent states, Fock states with a definite
photon number and Schrodinger cat states which are superpositions of coherent
states with different phases. These states are equivalently represented by
their density matrices in the photon-number basis or by their Wigner functions,
which are distributions of the field complex amplitude. Quasi-classical
coherent states have a Gaussian-shaped Wigner function while Fock and
Schrodinger cat Wigner functions show oscillations and negativities revealing
quantum interferences. Cavity damping induces decoherence which quickly washes
out the Wigner functions oscillations. We observe this process and realize
movies of decoherence by reconstructing snapshots of Schrodinger cat states at
successive times.