title: The Integrated Polarization of Spiral Galaxy Disks

abstract:
  We present integrated polarization properties of nearby spiral galaxies at
4.8 GHz, and models for the integrated polarization of spiral galaxy disks as a
function of inclination. Spiral galaxies in our sample have observed integrated
fractional polarization in the range < 1% to 17.6%. At inclinations less than
50 degrees, the fractional polarization depends mostly on the ratio of random
to regular magnetic field strength. At higher inclinations, Faraday
depolarization associated with the regular magnetic field becomes more
important. The observed degree of polarization is lower (<4%) for more luminous
galaxies, in particular those with L_{4.8} > 2 x 10^{21} W/Hz. The polarization
angle of the integrated emission is aligned with the apparent minor axis of the
disk for galaxies without a bar. In our axially symmetric models, the
polarization angle of the integrated emission is independent of wavelength.
Simulated distributions of fractional polarization for randomly oriented spiral
galaxies at 4.8 GHz and 1.4 GHz are presented. We conclude that polarization
measurements, e.g. with the SKA, of unresolved spiral galaxies allow
statistical studies of the magnetic field in disk galaxies using large samples
in the local universe and at high redshift. As these galaxies behave as
idealized background sources without internal Faraday rotation, they can be
used to detect large-scale magnetic fields in the intergalactic medium.


title:
Are the kinematics of DLAs in agreement with their arising in the gas
  disks of galaxies?

abstract:
  We demonstrate in this paper that the velocity widths of the neutral gas in
Damped Ly Alpha (DLA) systems are inconsistent with these systems originating
in gas disks of galaxies similar to those seen in the local Universe. We
examine the gas kinematics of local galaxies using the high quality HI 21-cm
data from the HI Nearby Galaxies Survey (THINGS) and make a comparison with the
velocity profiles measured in the low-ionization metal lines observed in DLAs
at high redshifts. The median velocity width of z=0 HI gas above the DLA column
density limit of N=2x10^20 cm-2 is approximately 30 km/s, whereas the typical
value in DLAs is a factor of two higher. We argue that the gas kinematics at
higher redshifts are increasingly influenced by gas that is not participating
in ordered rotation in cold disks, but is more likely associated with tidal gas
related to galaxy interactions or processes such as superwinds and outflows. An
analysis of the HI in the local interacting star-burst galaxy M82 shows that
the velocity widths in this galaxy are indeed similar to what is seen in DLAs.


title: Equivariant asymptotics for Toeplitz operators

abstract:
  In recent years, the Tian-Zelditch asymptotic expansion for the equivariant
components of the Szeg\"{o} kernel of a polarized complex projective manifold,
and its subsequent generalizations in terms of scaling limits, have played an
important role in algebraic, symplectic, and differential geometry. A natural
question is whether there exist generalizations in which the projector onto the
spaces of holomorphic sections can be replaced by the projector onto more
general (non-complete) linear series. One case that lends itself to such
analysis, and which is natural from the point of view of geometric
quantization, is given by the linear series determined by imposing spectral
bounds on an invariant self-adjoint Toeplitz operator. In this paper we focus
on the asymptotics of the spectral projectors associated to slowly shrinking
spectral bands.


title: Quark matter influence on observational properties of compact stars

abstract:
  Densities in compact stars may be such that quarks are no longer confined in
hadrons, but instead behave as weakly interacting particles. In this regime
perturbative calculations are possible. Yet, due to high pressures and an
attractive channel in the strong force, condensation of quarks in a superfluid
state is likely. This can have interesting consequences for magnetic fields,
especially in relation to the discovery of slow-period free precession in a
compact star. In this proceedings there will be a discussion of the mass-radius
relations of compact stars made from quark matter and magnetic field behaviour
in compact stars with a quark matter core.


title:
Laser-induced alignment and orientation of quantum-state-selected large
  molecules

abstract:
  A strong inhomogeneous static electric field is used to spatially disperse a
supersonic beam of polar molecules, according to their quantum state. We show
that the molecules residing in the lowest-lying rotational states can be
selected and used as targets for further experiments. As an illustration, we
demonstrate an unprecedented degree of laser-induced 1D alignment
$(<\cos^2\theta_{2D}>=0.97)$ and strong orientation of state-selected
iodobenzene molecules. This method should enable experiments on pure samples of
polar molecules in their rotational ground state, offering new opportunities in
molecular science.

categories: physics.chem-ph physics.atm-clus physics.atom-ph physics.ins-det


title:
Polarization of asteroid (387) Aquitania: the newest member of a class
  of large inversion angle asteroids

abstract:
  We present new imaging polarimetric observations of two Main Belt asteroids,
(234) Barbara and (387) Aquitania, taken in the first half of 2008 using the
Dual-Beam Imaging Polarimeter on the University of Hawaii 2.2 meter telescope,
located on Mauna Kea, Hawaii. Barbara had been previously shown to exhibit a
very unusual polarization-phase curve by Cellino, et al. (2006). Our
observations confirm this result and add Aquitania to the growing class of
large inversion angle objects. Interestingly, these asteroids show spinel
features in their IR spectra suggesting a mineralogical origin to the phase
angle-dependent polarimetric features. As spinel is associated with
calcium-aluminum-rich inclusions and carbonaceous chondrites, these large
inversion angle asteroids may represent some of the oldest surfaces in the
solar system. Circular as well as linear polarization measurements were
obtained but circular polarization was not detected.


title: Non-uniform hyperbolicity in complex dynamics

abstract:
  We study rational functions satisfying summability conditions - a family of
weak conditions on the expansion along the critical orbits. Assuming their
appropriate versions, we derive many nice properties:
  There exists a unique, ergodic, and non-atomic conformal measure with
exponent equal to the Hausdorff dimension of the Julia set.
  There is an absolutely continuous invariant measure with respect to this
conformal measure.
  The Minkowski dimension of the Julia set is strictly less than 2.
  Either the Julia set is the whole sphere, or the dynamics is unstable.
  For such polynomials and Blaschke products the Julia set is conformally
removable.
  The connected components of the boundary of invariant Fatou components are
locally connected.
  Finally, we derive a conformal analogue of Jakobson-Benedicks-Carleson
theorem and prove the external continuity of the Hausdorff dimension of Julia
sets for almost all points in the Mandelbrot set with respect to the harmonic
measure.
  Some of the results extend to the multimodal maps of an interval.


title: Direct Hamiltonization for Nambu Systems

abstract:
  The direct hamiltonization procedure applied to Nambu mechanical systems
proves that the Nambu mechanics is an usual mechanics described by only one
Hamiltonian. Thus a particular case of Hamiltonian mechanics. It is also proved
that any mechanical system described by the equation d{\bf r}/dt={\bf A(r)} is
a Nambu system.


title: Non-Negative Matrix Factorization, Convexity and Isometry

abstract:
  In this paper we explore avenues for improving the reliability of
dimensionality reduction methods such as Non-Negative Matrix Factorization
(NMF) as interpretive exploratory data analysis tools. We first explore the
difficulties of the optimization problem underlying NMF, showing for the first
time that non-trivial NMF solutions always exist and that the optimization
problem is actually convex, by using the theory of Completely Positive
Factorization. We subsequently explore four novel approaches to finding
globally-optimal NMF solutions using various ideas from convex optimization. We
then develop a new method, isometric NMF (isoNMF), which preserves
non-negativity while also providing an isometric embedding, simultaneously
achieving two properties which are helpful for interpretation. Though it
results in a more difficult optimization problem, we show experimentally that
the resulting method is scalable and even achieves more compact spectra than
standard NMF.


title: Antiferromagnetism in two-dimensional quasicrystals

abstract:
  Quasiperiodic structures possess long range positional order, but are freed
of constraints imposed by translational invariance. For spins interacting via
Heisenberg couplings, one may expect therefore to find novel magnetic
configurations in such structures. We have studied magnetic properties for
simple two dimensional models, as a first step towards understanding
experimentally studied magnetic quasicrystals such as the Zn-Mg-R(rare earth)
compounds. We analyse properties of the antiferromagnetic ground state and
magnon excitation modes for bipartite tilings such as the octagonal and Penrose
tilings. In the absence of frustration, one has an inhomogeneous Neel-ordered
ground state, with local quantum fluctuations of the local staggered magnetic
order parameter. We study the spin wave spectrum and wavefunctions of such
antiferromagnets within the linear spin wave approximation. Some results for
spin-spin correlations in these systems are discussed.


title: Counting interesting elections

abstract:
  We provide an elementary proof of a formula for the number of northeast
lattice paths that lie in a certain region of the plane. Equivalently, this
formula counts the lattice points inside the Pitman--Stanley polytope of an
n-tuple.


title: GRB 080913 at redshift 6.7

abstract:
  We report on the detection by Swift of GRB 080913, and subsequent
optical/near-infrared follow-up observations by GROND which led to the
discovery of its optical/NIR afterglow and the recognition of its high-z nature
via the detection of a spectral break between the i' and z' bands. Spectroscopy
obtained at the ESO-VLT revealed a continuum extending down to lambda = 9400 A,
and zero flux for 7500 A < lambda<9400 A, which we interpret as the onset of a
Gunn-Peterson trough at z=6.695+-0.025 (95.5% conf. level), making GRB 080913
the highest redshift GRB to date, and more distant than the highest-redshift
QSO. We note that many redshift indicators which are based on promptly
available burst or afterglow properties have failed for GRB 080913. We report
on our follow-up campaign and compare the properties of GRB 080913 with bursts
at lower redshift. In particular, since the afterglow of this burst is fainter
than typical for GRBs, we show that 2m-class telescopes can identify most
high-redshift GRBs.


title: Szego limit theorems on the Sierpinski gasket

abstract:
  We use the existence of localized eigenfunctions of the Laplacian on the
Sierpinski gasket to formulate and prove analogues of the strong Szego limit
theorem in this fractal setting. Furthermore, we recast some of our results in
terms of equally distributed sequences.


title: Superconductivity from gauge/gravity duality with flavor

abstract:
  We consider thermal strongly-coupled N=2 SYM theory with fundamental matter
at finite isospin chemical potential. Using gauge/gravity duality, i.e. a probe
of two flavor D7-branes embedded in the AdS black hole background, we find a
critical temperature at which the system undergoes a second order phase
transition. The critical exponent of this transition is one half and coincides
with the result from mean field theory. In the thermodynamically favored phase,
a flavor current acquires a vev and breaks an Abelian symmetry spontaneously.
This new phase shows signatures known from superconductivity, such as an
infinite dc conductivity and a gap in the frequency-dependent conductivity. The
gravity setup allows for an explicit identification of the degrees of freedom
in the dual field theory, as well as for a dual string picture of the
condensation process.


title: Virtual Observatory activities in the AMIGA group

abstract:
  The AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies)
is an international collaboration led from the Instituto de Astrof\'isica de
Andaluc\'ia (CSIC). The group's experience in radio astronomy databases turned,
as a natural evolution, into an active participation in the development of data
archives and radio astronomy software. The contributions of the group to the VO
have been mostly oriented towards the deployment of large VO compliant
databases and the development of access interfaces (IRAM 30m Pico Veleta,
DSS-63 70m in Robledo de Chavela). We also have been working in the development
of an API for VO tools that will ease access to VO registries and communication
between different VO software. A collaboration with the Kapteyn Astronomical
Institute has started recently in order to perform a complete renovation of the
only existing high-level software (GIPSY) for the analysis of datacubes,
allowing its fully integration in the VO.


title: Sur la dualite et la descente d'Iwasawa

abstract:
  We develop a formalism for studying descent and codescent in the context of
Iwasawa theory. The main result essentially states that to control descent or
codescent amounts to the same. Arithmetic applications are given.


title: Entanglement Theory and the Second Law of Thermodynamics

abstract:
  Entanglement is central both to the foundations of quantum theory and, as a
novel resource, to quantum information science. The theory of entanglement
establishes basic laws, such as the non-increase of entanglement under local
operations, that govern its manipulation and aims to draw from them formal
analogies to the second law of thermodynamics. However, while in the second law
the entropy uniquely determines whether a state is adiabatically accessible
from another, the manipulation of entanglement under local operations exhibits
a fundamental irreversibility which prevents the existence of such an order.
  Here we show that a reversible theory of entanglement and a rigorous
relationship with thermodynamics may be established when one considers all
non-entangling transformations. The role of the entropy in the second law is
taken by the asymptotic relative entropy of entanglement in the basic law of
entanglement. We show the usefulness of this new approach to general resource
theories and to quantum information theory.


title:
Antiferromagnetic Correlation and the Pairing Mechanism of the Cuprates
  and Iron Pnictides : a View From the Functional Renormalization Group Studies

abstract:
  We compare the one-loop functional renormalization group results for the
cuprates and the iron pnictides. Interestingly a coherent picture suggesting
that antiferromagnetic correlation causes pairing for both materials emerges.


title:
Thickness-tuned Superconductor-to-Insulator Transitions under magnetic
  field in a-NbSi

abstract:
  We have studied the thickness-induced superconductor-to-insulator transition
in the presence of a magnetic field for a-NbSi thin films. Analyzing the
critical behavior of this system within the "dirty boson model", we have found
a critical exponents product of $\nu_d z$ > 0.4. The corresponding phase
diagram in the (H,d) plane is inferred. This small exponent product as well as
the non-universal value of the critical resistance found at the transition call
for further investigations in order to thoroughly understand these transitions.


title:
Unified ab initio treatment of attosecond photoionization and Compton
  scattering

abstract:
  We present a new theoretical approach to attosecond laser-assisted photo- and
Compton ionization. Attosecond x-ray absorption and scattering are described by
$\hat{\mathrsfs{S}}^{(1,2)}$-matrices, which are coherent superpositions of
"monochromatic" $\hat{S}^{(1,2)}$-matrices in a laser-modified Furry
representation. Besides refining the existing theory of the soft x-ray
photoelectron attosecond streak camera and spectral phase interferometry (ASC
and ASPI), we formulate a theory of hard x-ray photoelectron and Compton ASC
and ASPI. The resulting scheme has a simple structure and leads to closed-form
expressions for ionization amplitudes. We investigate Compton electron
interference in the separable Coulomb-Volkov continuum with both Coulomb and
laser fields treated non-perturbatively. We find that at laser-field
intensities below 10$^{13}$ Wcm$^{-2}$ normalized Compton lines almost coincide
with the lines obtained in the laser-free regime. At higher intensities,
attosecond interferences survive integration over electron momenta, and feature
prominently in the Compton lines themselves. We define a regime where the
electron ground-state density can be measured with controllable accuracy in an
attosecond time interval. The new theory provides a firm basis for extracting
photo- and Compton electron phases and atomic and molecular wavefunctions from
experimental data.


title: On Outage and Error Rate Analysis of the Ordered V-BLAST

abstract:
  Outage and error rate performance of the ordered BLAST with more than 2
transmit antennas is evaluated for i.i.d. Rayleigh fading channels. A number of
lower and upper bounds on the 1st step outage probability at any SNR are
derived, which are further used to obtain accurate approximations to average
block and total error rates. For m Tx antennas, the effect of the optimal
ordering at the first step is an m-fold SNR gain. As m increases to infinity,
the BLER decreases to zero, which is a manifestation of the space-time
autocoding effect in the V-BLAST. While the sub-optimal ordering (based on the
before-projection SNR) suffers a few dB SNR penalty compared to the optimal
one, it has a lower computational complexity and a 3 dB SNR gain compared to
the unordered V-BLAST and can be an attractive solution for
low-complexity/low-energy systems. Uncoded D-BLAST exhibits the same outage and
error rate performance as that of the V-BLAST. An SNR penalty of the linear
receiver interfaces compared to the BLAST is also evaluated.


title:
Central Limit Theorem and recurrence for random walks in bistochastic
  random environments

abstract:
  We prove the annealed Central Limit Theorem for random walks in bistochastic
random environments on $Z^d$ with zero local drift. The proof is based on a
"dynamicist's interpretation" of the system, and requires a much weaker
condition than the customary uniform ellipticity. Moreover, recurrence is
derived for $d \le 2$.


title: A note on Artin's constant

abstract:
  We suggest a new approach to Artin's constant that leads to its
representation as an infinite sum divided by another infinite sum. The same
approach works well for Stephens' constant and higher rank Artin's constants.
The main results are theoretical but there are interesting experimental and
computational aspects.


title:
Well-posedness results for triply nonlinear degenerate parabolic
  equations

abstract:
  We study the well-posedness of triply nonlinear degenerate
elliptic-parabolic-hyperbolic problem $$ b(u)_t - {\rm div} \tilde{\mathfrak
a}(u,\nabla\phi(u))+\psi(u)=f, \quad u|_{t=0}=u_0 $$ in a bounded domain with
homogeneous Dirichlet boundary conditions. The nonlinearities $b,\phi$ and
$\psi$ are supposed to be continuous non-decreasing, and the nonlinearity
$\tilde{\mathfrak a}$ falls within the Leray-Lions framework. Some restrictions
are imposed on the dependence of $\tilde{\mathfrak a}(u,\nabla\phi(u))$ on $u$
and also on the set where $\phi$ degenerates. A model case is $\tilde{\mathfrak
a}(u,\nabla\phi(u))
=\tilde{\mathfrak{f}}(b(u),\psi(u),\phi(u))+k(u)\mathfrak{a}_0(\nabla\phi(u)),$
with $\phi$ which is strictly increasing except on a locally finite number of
segments, and $\mathfrak{a}_0$ which is of the Leray-Lions kind. We are
interested in existence, uniqueness and stability of entropy solutions. If
$b=\mathrm{Id}$, we obtain a general continuous dependence result on data
$u_0,f$ and nonlinearities $b,\psi,\phi,\tilde{\mathfrak{a}}$. Similar result
is shown for the degenerate elliptic problem which corresponds to the case of
$b\equiv 0$ and general non-decreasing surjective $\psi$. Existence, uniqueness
and continuous dependence on data $u_0,f$ are shown when $[b+\psi](\R)=\R$ and
$\phi\circ [b+\psi]^{-1}$ is continuous.


title:
Distinguishability of quantum states under restricted families of
  measurements with an application to quantum data hiding

abstract:
  Every sufficiently rich set of measurements on a fixed quantum system defines
a statistical norm on the states of that system via the optimal bias that can
be achieved in distinguishing the states using measurements from that set
(assuming equal priors). The Holevo-Helstrom theorem says that for the set of
all measurements this norm is the trace norm. For finite dimension any norm is
lower and upper bounded by constant (though dimension dependent) multiples of
the trace norm, so we set ourselves the task of computing or bounding the best
possible "constants of domination" for the norms corresponding to various
restricted sets of measurements, thereby determining the worst case and best
case performance of these sets relative to the set of all measurements.
  We look at the case where the allowed set consists of a single measurement,
namely the uniformly random continuous POVM and its approximations by 2-designs
and 4-designs respectively. Here we find asymptotically tight bounds for the
constants of domination.
  Furthermore, we analyse the multipartite setting with any LOCC measurement
allowed. In the case of two parties, we show that the lower domination constant
is the same as that of a tensor product of local uniformly random POVMs (up to
a constant). This answers in the affirmative an open question about the
(near-)optimality of bipartite data hiding: The bias that can be achieved by
LOCC in discriminating two orthogonal states of a d x d bipartite system is
Omega(1/d), which is known to be tight. Finally, we use our analysis to derive
certainty relations (in the sense of Sanchez-Ruiz) for any such measurements
and to lower bound the locally accessible information for bipartite systems.


title: Measurements of D and Ds decay constants at CLEO

abstract:
  Using CLEO data collected at 3370 MeV and 4170 MeV, we determine fD = (205.8
+- 8.5 +- 2.5) MeV and an interim preliminary value of fDs = (267.9 +- 8.2 +-
3.9) MeV, where both results are radiatively corrected. They agree with the
recent most precise unquenched Lattice-QCD calculation for the D+, but do not
for the Ds. Several consequences are discussed.


title: Repulsive electromagnetic stresses in the Casimir piston

abstract:
  This manuscript has been withdrawn, since the authors have detected numerical
inaccuracies that invalidate their main results concerning the existence of
repulsive Casimir forces within a rectangular piston. Formulas presented in the
manuscript keep still valid. The authors deeply apologize for this mistake.


title: Search for the 3He-eta bound state at COSY-11

abstract:
  We have measured excitation function for dp -> ppp_pi- reaction near the eta
production threshold. We observe an enhancement of the counting rate above the
threshold which can originate from the production of the eta meson in the
reaction dp -> 3He eta and its subsequent absorption on neutron in the 3He
nucleus leading to creation of the p_pi- pair.


title: Three fermions in a box

abstract:
  I calculate finite-volume effects for three identical spin-1/2 fermions in a
box assuming short-ranged repulsive interactions of `natural size'. This
analysis employs standard perturbation theory in powers of 1/L, where L^3 is
the volume of the box. I give results for the ground states in the A_1, T_1,
and E cubic representations.


title:
Theory of magnetic field-induced metaelectric critical end point in
  BiMn$_2$O$_5$

abstract:
  A recent experiment on the multiferroic BiMn$_2$O$_5$ compound under a strong
applied magnetic field revealed a rich phase diagram driven by the coupling of
magnetic and charge (dipolar) degrees of freedom. Based on the
exchange-striction mechanism, we propose here a theoretical model with the
intent to capture the interplay of the spin and dipolar moments in the presence
of a magnetic field in BiMn$_2$O$_5$. Experimentally observed behavior of the
dielectric constants, magnetic susceptibility, and the polarization is, for the
most part, reproduced by our model. The critical behavior observed near the
polarization reversal $(P=0)$ point in the phase diagram is interpreted as
arising from the proximity to the critical end point.


title: Infrared finite effective charge of QCD

abstract:
  We show that the gauge invariant treatment of the Schwinger-Dyson equations
of QCD leads to an infrared finite gluon propagator, signaling the dynamical
generation of an effective gluon mass, and a non-enhanced ghost propagator, in
qualitative agreement with recent lattice data. The truncation scheme employed
is based on the synergy between the pinch technique and the background field
method. One of its most powerful features is that the transversality of the
gluon self-energy is manifestly preserved, exactly as dictated by the BRST
symmetry of the theory. We then explain, for the first time in the literature,
how to construct non-perturbatively a renormalization group invariant quantity
out of the conventional gluon propagator. This newly constructed quantity
serves as the natural starting point for defining a non-perturbative effective
charge for QCD, which constitutes, in all respects, the generalization in a
non-Abelian context of the universal QED effective charge. This strong
effective charge displays asymptotic freedom in the ultraviolet, while in the
low-energy regime it freezes at a finite value, giving rise to an infrared
fixed point for QCD. Some possible pitfalls related to the extraction of such
an effective charge from infrared finite gluon propagators, such as those found
on the lattice, are briefly discussed.


title:
Multi-point quasi-rational approximants for the energy eigenvalues of
  potentials of the form V(x)= Ax^a + Bx^b

abstract:
  Analytic approximants for the eigenvalues of the one-dimensional
Schr\"odinger equation with potentials of the form $V(x)= Ax^a + Bx^b$ are
found using a multi-point quasi-rational approximation technique. This
technique is based on the use of the power series and asymptotic expansion of
the eigenvalues in $\lambda=A^{-\frac{b+2}{a+2}}B$, as well as the expansion at
intermediate points. These expansions are found through a system of
differential equations. The approximants found are valid and accurate for any
value of $\lambda$. As examples, the technique is applied to the quartic and
sextic anharmonic oscillators.


title:
A new construction of the asymptotic algebra associated to the $q$-Schur
  algebra

abstract:
  We denote by A the ring of Laurent polynomials in the indeterminate v and by
K its field of fractions. In this paper, we are interested in representation
theory of the "generic" q-Schur algebra S_q(n,r) over A. We will associate to
every non-degenerate symmetrising trace form \tau on KS_q(n,r) a subalgebra
J_{\tau} of KS_q(n,r) which is isomorphic to the "asymptotic" algebra \J(n,r)_A
defined by J. Du. As a consequence, we give a new criterion for James'
conjecture.


title: A Mordell Inequality for Lattices over Maximal Orders

abstract:
  In this paper we prove an analogue of Mordell's inequality for lattices in
finite-dimensional complex or quaternionic Hermitian space that are modules
over a maximal order in an imaginary quadratic number field or a totally
definite rational quaternion algebra. This inequality implies that the
16-dimensional Barnes-Wall lattice has optimal density among all 16-dimensional
lattices with Hurwitz structures.


title: Non-Markovian Quantum Jump with Generalized Lindblad Master Equation

abstract:
  The Monte Carlo wave function method or the quantum trajectory/jump approach
is a powerful tool to study dissipative dynamics governed by the Markovian
master equation, in particular for high-dimensional systems and when it is
difficult to simulate directly. In this paper, we extend this method to the
non-Markovian case described by the generalized Lindblad master equation. Two
examples to illustrate the method are presented and discussed. The results show
that the method can correctly reproduce the dissipative dynamics for the
system. The difference between this method and the traditional Markovian jump
approach and the computational efficiency of this method are also discussed.


title: Blind and non-blind source detection in WMAP 5-year maps

abstract:
  We have analyzed the efficiency in source detection and flux density
estimation of blind and non-blind detection techniques exploiting the MHW2
filter applied to the Wilkinson Microwave Anisotropy Probe (WMAP) 5-year maps.
A comparison with the AT20G Bright Source Sample (Massardi et al. 2008), with a
completeness limit of 0.5 Jy and accurate flux measurements at 20 GHz, close to
the lowest frequency of WMAP maps, has allowed us to assess the completeness
and the reliability of the samples detected with the two approaches, as well as
the accuracy of flux and error estimates, and their variations across the sky.
The uncertainties on flux estimates given by our procedure turned out to be
about a factor of 2 lower than the rms differences with AT20G measurements,
consistent with the smoothing of the fluctuation field yielded by map
filtering. Flux estimates were found to be essentially unbiased except that,
close to the detection limit, a substantial fraction of fluxes are found to be
inflated by the contribution of underlying positive fluctuations. This is
consistent with expectations for the Eddington bias associated to the true
errors on flux density estimates. The blind and non-blind approaches are found
to be complementary: each of them allows the detection of sources missed by the
other. Combining results of the two methods on the WMAP 5-year maps we have
expanded the non-blindly generated New Extragalactic WMAP Point Source (NEWPS)
catalogue (Lopez-Caniego et al. 2007) that was based on WMAP 3-year maps. After
having removed the probably spurious objects not identified with known radio
sources, the new version of the NEWPS catalogue, NEWPS_5yr comprises 484
sources detected with a signal-to-noise ratio SNR>5.


title:
Temperature-dependent screening of the edge state around antidots in the
  quantum Hall regime

abstract:
  The Aharonov-Bohm (AB) effect in a small array of antidots with large aspect
ratio is investigated in the quantum Hall regime. The evolution with
temperature of the AB oscillations in the magnetic field vs gate voltage (B-Vg)
plane reveals the temperature dependence of the screening. The
self-consistently screened potential of the compressible band surrounding an
antidot is observed to gain progressively steeper slope with increasing
temperature.


title: GIT Constructions of Moduli Spaces of Stable Curves and Maps

abstract:
  This largely expository paper first gives an introduction to Hilbert
stability and its use in Gieseker's GIT construction of $\overline{M}_g$. Then
I review recent work in this area--variants for unpointed curves that arise in
Hassett's log minimal model program, starting with Schubert's moduli space of
pseudostable curves, and constructions for weighted pointed stable curves and
for pointed stable maps due to Swinarski and to Baldwin and Swinarski
respectively. The focus is on the steps at which new ideas are needed. Finally,
I list open problems in the area, particularly some arising in the log minimal
model program that seem inaccessible to current techniques.


title: Imaging protein interactions in vivo with sub-cellular resolution

abstract:
  Resonant Energy Transfer (RET) from an optically excited donor molecule (D)
to a non-excited acceptor molecule (A) residing nearby is widely used to detect
molecular interactions in living cells. Stoichiometric information, such as the
number of proteins forming a complex, has been obtained so far for a handful of
proteins, but only after exposing the sample sequentially to at least two
different excitation wavelengths. During this lengthy process of measurement,
the molecular makeup of a cellular region may change, and this has so far
limited the applicability of RET to determination of cellular averages. Here we
demonstrate a method for imaging protein complex distribution in living cells
with sub-cellular spatial resolution, which relies on a spectrally-resolved
two-photon microscope, a simple but competent theory, and a keen selection of
fluorescent tags. This technology may eventually lead to tracking dynamics of
macromolecular complex formation and dissociation with spatial resolution
inside living cells.


title:
Effective magnetic penetration depth in superconducting cylinders and
  spheres with highly anisotropic electrodynamics

abstract:
  Effective magnetic penetration depth and microwave surface impedance are
derived for anisotropic layered superconductors in the shape of spheres and
long cylinders, where the external magnetic field is applied in the plane of
the highly conducting layers to induce out-of-plane screening currents. The
results are extended by analytic continuation to highly anisotropic conductors
and to lossy superconductors at high frequency. The electrodynamics for the
general case of a superconductor or metal with arbitrary anisotropy are
presented. The treatment is then specialized to layered materials with
unixaxial anisotropy, in which the penetration depth for currents flowing
perpendicular to the layers, lambda_c, is much greater than that for in-plane
currents, lambda_a. Exact solutions are found in the limit lambda_a goes to
zero, and are expected to provide an accurate representation of many
experiments on cuprates and other layered superconductors, particularly on
grain-aligned powders.


title:
Our Nearest 15 Million Neighbors: The Field Low-Mass Stellar Luminosity
  and Mass Functions

abstract:
  We report on a new measurement of the luminosity function (LF) and mass
function (MF) of field low-mass dwarfs using Sloan Digital Sky Survey (SDSS)
photometry. The final catalog is composed of ~15 million low-mass stars (0.1
Msun < M < 0.8 Msun), spread over 8,400 square degrees. Distances to the stars
are estimated using new photometric parallax relations, constructed from ugriz
photometry of nearby low-mass stars with trigonometric parallaxes. The LF is
measured with a novel technique, which simultaneously measures Galactic
structure and the stellar LF. The resulting LF is compared to previous studies
and converted to a MF. The MF is well-described by a log-normal distribution,
with Mo = 0.27 Msun.


title: Exact Hydrodynamics of the Lattice BGK Equation

abstract:
  We apply the projection operator formalism to the problem of determining the
asymptotic behavior of the lattice BGK equation in the hydrodynamic limit. As
an alternative to the more usual Chapman-Enskog expansion, this approach offers
many benefits. Most remarkably, it produces absolutely exact, though
non-Markovian, hydrodynamic difference equations as an intermediate step. These
are accurate to all orders in Knudsen number and hence contain all of the
physics of the Burnett equations and beyond. If appropriate, these equations
may then be Taylor expanded to second order in Knudsen number to obtain the
usual hydrodynamic equations that result from the Chapman-Enskog analysis. The
method offers the potential to derive hydrodynamic difference equations for
complex fluids with sharp gradients, such as immiscible and amphiphilic flow,
for which the assumptions underlying the Chapman-Enskog approach are generally
invalid.


title: Diagrammatic Monte Carlo simulation of non-equilibrium systems

abstract:
  We generalize the recently developed diagrammatic Monte Carlo techniques for
quantum impurity models from an imaginary time to a Keldysh formalism suitable
for real-time and nonequilibrium calculations. Both weak-coupling and
strong-coupling based methods are introduced, analysed and applied to the study
of transport and relaxation dynamics in interacting quantum dots.


title:
Embeddings of 3-manifolds in S^4 from the point of view of the
  11-tetrahedron census

abstract:
  This is a collection of notes on embedding problems for 3-manifolds. The main
question explored is `which 3-manifolds embed smoothly in the 4-sphere?' The
terrain of exploration is the Burton/Martelli/Matveev/Petronio census of
triangulated prime closed 3-manifolds built from 11 or less tetrahedra. There
are 13766 manifolds in the census, of which 13400 are orientable. Of the 13400
orientable manifolds, only 149 of them have hyperbolic torsion linking forms
and are thus candidates for embedability in the 4-sphere. The majority of this
paper is devoted to the embedding problem for these 149 manifolds. At present
41 are known to embed. Among the remaining manifolds, embeddings into homotopy
4-spheres are constructed for 4. 67 manifolds are known to not embed in the
4-sphere. This leaves 37 unresolved cases, of which only 3 are geometric
manifolds i.e. having a trivial JSJ-decomposition.


title:
Spin and density excitations in the triangular-lattice $t$-$J$ model
  with multiple-spin exchange interactions: $^3$He on graphite

abstract:
  Using an exact diagonalization technique on small clusters, we study spin and
density excitations of the triangular-lattice $t$-$J$ model with multiple-spin
exchange interactions, whereby we consider anomalous properties observed in the
doped Mott region of the two-dimensional liquid $^3$He adsorbed on a graphite
surface. We find that the double-peak structure consistent with experiment
appears in the calculated temperature dependence of the specific heat; the
low-temperature sharp peak comes from the spin excitations reflecting the
frustrated nature of the spin degrees of freedom and high-temperature broad
peak comes from the density excitations extending over the entire band width.
The clear separation in their energy scales is evident in the calculated spin
and density excitation spectra. The calculated single-particle excitation
spectra suggest the presence of fermionic quasiparticles dressed by the spin
excitations, with an enhanced effective mass consistent with experiment.


title:
Rotational Mixing in Magellanic Clouds B Stars - Theory versus
  Observation

abstract:
  We have used VLT FLAMES data to constrain the uncertain physics of rotational
mixing in stellar evolution models. We have simulated a population of single
stars and find two groups of observed stars that cannot be explained: (1) a
group of fast rotating stars which do not show evidence for rotational mixing
and (2) a group of slow rotators with strong N enrichment. Binary effects and
fossil magnetic fields may be considered to explain those two groups. We
suggest that the element boron could be used to distinguish between rotational
mixing and the binary scenario. Our single star population simulations quantify
the expected amount of boron in fast and slow rotators and allow a comparison
with measured nitrogen and boron abundances in B-stars.


title: Finite Density Simulations with Canonical Ensemble

abstract:
  QCD at non-zero baryon density is expected to have a critical point where the
zero-density cross-over turns into a first order phase transition. To identify
this point we scan the density-temperature space using a canonical ensemble
method. For a given temperature, we plot the chemical potential as a function
of density looking for an "S-shape" as a signal for a first order transition.
We carried out simulations using Wilson fermions with $m_\pi \approx 1{GeV}$ on
$6^3\times 4$ lattices. As a benchmark, we ran four flavors simulations where
we observe a clear signal. In the two flavors case we do not see any signal for
temperatures as low as $0.83 T_c$. Preliminary results for the three flavor
case are also presented.


title: Strong time operators associated with generalized Hamiltonians

abstract:
  Let the pair of operators, $(H, T)$, satisfy the weak Weyl relation:
$Te^{-itH} = e^{-itH}(T + t)$, where $H$ is self-adjoint and $T$ is closed
symmetric. Suppose that g is a realvalued Lebesgue measurable function on $\RR$
such that $g \in C^2(R K)$ for some closed subset $K \subset \RR$ with Lebesgue
measure zero. Then we can construct a closed symmetric operator $D$ such that
$(g(H), D)$ also obeys the weak Weyl relation.


title:
Cobalt-substitution-induced Superconductivity in a New Compound with
  ZrCuSiAs-type Structure, SrFeAsF

abstract:
  We have synthesized a quaternary fluoroarsenide SrFeAsF with the
ZrCuSiAs-type structure (P4/nmm, a = 0.3999 and c = 0.8973 nm), which is
composed of an alternately stacked (FeAs)- and (SrF)+ layers, analogous to the
FeAs-based superconductor LaFeAsO. SrFeAsF shows metallic type conduction with
the anomaly at ~180 K. The partial replacement of the Fe with Co suppresses the
anomaly and induces the superconductivity, while the maximal Tc (4 K for
SrFe0.875Co0.125AsF) is much lower than that of the Co-substituted LaFeAsO.
Replacement of (LaO)+ layers with (SrF)+ layers results in a enlargement of the
c-axis length (+2.6%). These results suggest the importance of interlayer
interaction as a critical Tc-controlling factor in FeAs-based superconductors.


title: Interference Channels with Correlated Receiver Side Information

abstract:
  The problem of joint source-channel coding in transmitting independent
sources over interference channels with correlated receiver side information is
studied. When each receiver has side information correlated with its own
desired source, it is shown that source-channel code separation is optimal.
When each receiver has side information correlated with the interfering source,
sufficient conditions for reliable transmission are provided based on a joint
source-channel coding scheme using the superposition encoding and partial
decoding idea of Han and Kobayashi. When the receiver side information is a
deterministic function of the interfering source, source-channel code
separation is again shown to be optimal. As a special case, for a class of
Z-interference channels, when the side information of the receiver facing
interference is a deterministic function of the interfering source, necessary
and sufficient conditions for reliable transmission are provided in the form of
single letter expressions. As a byproduct of these joint source-channel coding
results, the capacity region of a class of Z-channels with degraded message
sets is also provided.


title: Searches for squarks and gluinos at D0

abstract:
  Recent results obtained by the D0 Collaboration on searches for squarks and
gluinos in proton-antiproton collisions at sqrt(s) =1.96 TeV at the Fermilab
Tevatron collider are discussed. For the inclusive searches, events with
multiple jets of hadrons and large missing transverse energy in the final state
are studied within the framework of minimal supergravity and assuming R-parity
conservation. Searches for the scalar top quark are studied in two final state
topologies: with events of two charm jets and large missing transverse energy
or leptons, jets and missing transverse energy. The data, corresponding to
integrated luminosities of up to 2.1/fb, show no excess of a signal above the
expected background in any of the decay channels examined. Instead, upper
limits at 95% Confidence Level on the squarks and gluino masses are derived.


abstract:
  We show $L^1$ is complemented in the dual space $L^{\infty *}$ for a finite
regular complex measure on a compact Hausdorff space


title: Generation of Circular Polarization of the Cosmic Microwave Background

abstract:
  The standard cosmological model, which includes only Compton scattering
photon interactions at energy scales near recombination, results in zero
primordial circular polarization of the cosmic microwave background. In this
paper we consider a particular renormalizable and gauge-invariant standard
model extension coupling photons to an external vector field via a Chern-Simons
term, which arises as a radiative correction if gravitational torsion couples
to fermions. We compute the transport equations for polarized photons from a
Boltzmann-like equation, showing that such a coupling will source circular
polarization of the microwave background. For the particular coupling
considered here, the circular polarization effect is always negligible compared
to the rotation of the linear polarization orientation, also derived using the
same formalism. We note the possibility that limits on microwave background
circular polarization may probe other photon interactions and related
fundamental effects such as violations of Lorentz invariance.


title: A mechanics for the Ricci flow

abstract:
  We construct the classical mechanics associated with a conformally flat
Riemannian metric on a compact, n-dimensional manifold without boundary. The
corresponding gradient Ricci flow equation turns out to equal the
time-dependent Hamilton-Jacobi equation of the mechanics so defined.


title: Projective module description of embedded noncommutative spaces

abstract:
  An algebraic formulation is given for the embedded noncommutative spaces over
the Moyal algebra developed in a geometric framework in \cite{CTZZ}. We
explicitly construct the projective modules corresponding to the tangent
bundles of the embedded noncommutative spaces, and recover from this algebraic
formulation the metric, Levi-Civita connection and related curvatures, which
were introduced geometrically in \cite{CTZZ}. Transformation rules for
connections and curvatures under general coordinate changes are given. A bar
involution on the Moyal algebra is discovered, and its consequences on the
noncommutative differential geometry are described.


title: Molecular Electroporation and the Transduction of Oligoarginines

abstract:
  Certain short polycations, such as TAT and polyarginine, rapidly pass through
the plasma membranes of mammalian cells by an unknown mechanism called
transduction as well as by endocytosis and macropinocytosis. These
cell-penetrating peptides (CPPs) promise to be medically useful when fused to
biologically active peptides. I offer a simple model in which one or more CPPs
and the phosphatidylserines of the inner leaflet form a kind of capacitor with
a voltage in excess of 180 mV, high enough to create a molecular electropore.
The model is consistent with an empirical upper limit on the cargo peptide of
40--60 amino acids and with experimental data on how the transduction of a
polyarginine-fluorophore into mouse C2C12 myoblasts depends on the number of
arginines in the CPP and on the CPP concentration. The model makes three
testable predictions.


title: On a problem of Specker about Euclidean representations of finite graphs

abstract:
  Say that a graph $G$ is \emph{representable in $\R ^n$} if there is a map $f$
from its vertex set into the Euclidean space $\R ^n$ such that $\| f(x) -
f(x')\| = \| f(y) - f(y')\|$ iff $\{x,x'\}$ and $\{y, y'\}$ are both edges or
both non-edges in $G$. The purpose of this note is to present the proof of the
following result, due to Einhorn and Schoenberg: if $G$ finite is neither
complete nor independent, then it is representable in $\R ^{|G|-2}$. A similar
result also holds in the case of finite complete edge-colored graphs.


title: No-Go Theorem of Leibniz Rule and Supersymmetry on the Lattice

abstract:
  An obstacle to realize supersymmetry on a lattice is the breakdown of Leibniz
rule. We give a proof of a no-go theorem that it is impossible to construct a
lattice field theory in an infinite lattice volume with any nontrivial field
products and difference operators that satisfy the following three properties:
(i) translation invariance, (ii) locality and (iii) Leibniz rule. We then
propose a way to escape from the no-go theorem by introducing infinite flavors,
and present a lattice model of N=2 supersymmetric quantum mechanics equipped
with the full exact supersymmetry.


title: 2-Vector Spaces and Groupoids

abstract:
  This paper describes a relationship between essentially finite groupoids and
2-vector spaces. In particular, we show to construct 2-vector spaces of
Vect-valued presheaves on such groupoids. We define 2-linear maps corresponding
to functors between groupoids in both a covariant and contravariant way, which
are ambidextrous adjoints. This is used to construct a representation--a weak
functor--from Span(Gpd) (the bicategory of groupoids and spans of groupoids)
into 2Vect. In this paper we prove this and give the construction in detail.


title:
Enhancement in superconducting transition temperature and upper critical
  field of LaO0.8F0.2FeAs with antimony doping

abstract:
  We report the synthesis and characterization of antimony doped oxypnictide
superconductor, LaO0.8F0.2FeAs1-xSbx (x = 0.05 and 0.10). The parent compound
LaOFeAs with fluorine doping exhibits superconductivity at maximum transition
temperature ~ 28.5 K [11]. Here we partially substitute As by Sb
(LaO0.8F0.2FeAs1-xSbx) and observe enhancement of the transition temperature to
30.1 K. This is the only instance so far where Tc increases with doping in the
conducting layer (FeAs) and this leads to the highest transition temperature in
any La-based oxypnictide. XRD and EDAX measurements confirm phase purity of the
samples and the presence of Sb. The magneto-resistance measurements show that
the value of upper critical field Hc2(0) to be about 73 T corresponding to a
coherence length of 22 angstrom. The Seebeck coefficient measurements indicate
electron transport with strong contribution from electron-electron correlation.
These results provide interesting insight to the origin of superconductivity in
these novel series of compounds.


title:
Possible Shape Coexistence and Magnetic Dipole Transitions in $^{17}$C
  and $^{21}$Ne

abstract:
  Magnetic dipole(M1) transitions of N=11 nuclei,
  $^{17}$C and $^{21}$Ne are investigated by using shell model and deformed
Skyrme Hartree-Fock+blocked BCS wave functions.
  Shell model calculations predict well observed energy spectra and magnetic
dipole transitions in $^{21}$Ne, while the results are rather poor to predict
these observables in $^{17}$C. In the deformed HF calculations, the ground
states of two nuclei are shown to have large prolate deformations close to
$\beta_2$=0.4. It is also pointed out that the first $K^{\pi}=1/2^+$ state in
$^{21}$Ne is prolately deformed, while the first $K^{\pi}=1/2^+$ state in
$^{17}$C is predicted to have a large oblate deformation being close to the
ground state in energy, We point out that experimentally observed large
hindrance of M1 transition between $I^{\pi}=1/2^+$ and $3/2^+$ in $^{17}$C can
be attributed to a shape coexistence near the ground state of $^{17}$C.


title:
Charm quark system in 2+1 flavor lattice QCD using the PACS-CS
  configurations

abstract:
  We study heavy-heavy and heavy-light quark systems for charm with a
relativistic heavy quark action in 2+1 flavor lattice QCD. Configurations are
generated by the PACS-CS Collaboration at the lattice spacing is $a=0.09$ fm
with the lattice size of $32^3\times 64$ employing the $O(a)$-improved Wilson
quark action and the Iwasaki gauge action. We present preliminary results for
the charmonium spectrum and the $D$ and $D_s$ meson decay constants evaluated
at 3.5 MeV$< m_{\rm ud}<$ 12 MeV with $m_{\rm s}$ around the physical value. We
investigate the dynamical quark mass dependences of the hyperfine and the
orbital splittings. The decay constants are compared with the recent
experimental values.


title: Into the bulk: reconstructing spacetime from the c=1 matrix model

abstract:
  We write down exact solutions in the collective field theory of the c=1
matrix model and in dilaton-gravity coupled to a massless scalar. Using the
known correspondence between these two theories at the null boundaries of
spacetime, we make a connection between scalar fields in these two theories in
the bulk of spacetime. In the process, we gain insight into how a theory
containing gravity can be equivalent to one without gravity. We analyze a
simple time-dependent background as an example.


title:
Clustering Properties and Model Wavefunctions for Non-Abelian Fractional
  Quantum Hall Quasielectrons

abstract:
  We present model wavefunctions for quasielectron (as opposed to quasihole)
excitations of the unitary $Z_k$ parafermion sequence
(Laughlin/Moore-Read/Read-Rezayi) of Fractional Quantum Hall states. We
uniquely define these states through two generalized clustering conditions:
they vanish when either a cluster of $k+2$ electrons is put together, or when
two clusters of $k+1$ electrons are formed at different positions. For Abelian
Fractional Quantum Hall states ($k=1$), our construction reproduces the Jain
quasielectron wavefunction, and elucidates the difference between the Jain and
Laughlin quasielectrons. For two (or more) quasielectrons, our states differ
from those constructed using Jain's method. By adding our quasielectrons to the
Laughlin state, we obtain a hierarchy scheme which gives rise the non-Abelian
non-unitary $\nu={2/5}$ FQH Gaffnian state.


title: Photoproduction in semiconductors by onset of magnetic field

abstract:
  The energy bands of a semiconductor are lowered by an external magnetic
field. When a field is switched on, the straight-line trajectories near the top
of the occupied valence band are curved into Landau orbits and Bremsstrahlung
is emitted until the electrons have settled in their final Fermi distribution.
We calculate the radiated energy, which should be experimentally detectable,
and suggest that a semiconductor can be cooled by an oscillating magnetic
field.


title: Structure of Neutron Star with a Quark Core

abstract:
  The equation of state of de-confined quark matter within the MIT bag model is
calculated. This equation of state is used to compute the structure of a
neutron star with quark core. It is found that the limiting mass of the neutron
star is affected considerably by this modification of the equation of state.
Calculations are carried out for different choices of the bag constant.


title:
The Non-relativistic Limit of the Euler Nordstr\"om System with
  Cosmological Constant

abstract:
  In this paper the author studies the singular limit c to infinity of the
family of Euler-Nordstr\"om systems indexed by the parameters kappa and c
(EN_kappa,c), where kappa^2 > 0 is the cosmological constant and c is the speed
of light. Using Christodoulou's techniques to generate energy currents, the
author develops Sobolev estimates that show that for initial data belonging to
an appropriate Sobolev space, as c tends to infinity, the solutions to the
EN_kappa,c system converge uniformly on a spacetime slab [0,T]xR^3 to the
solution of the Euler-Poisson system with the cosmological constant kappa^2.


title:
Incised-valley morphologies and sedimentary-fills within the inner shelf
  of the northern Bay of Biscay

abstract:
  This study is a first synthesis focused on incised-valleys located within the
inner shelf of the Bay of Biscay. It is based on previously published results
obtained during recent seismic surveys and coring campaigns. The morphology of
the valleys appears to be strongly controlled by tectonics and lithology. The
Pleistocene sedimentary cover of the shelf is very thin and discontinuous with
a maximum thickness ranging between 30 and 40 m in incised-valley fills. Thus
the incised bedrock morphology plays a key-role by controlling hydrodynamics
and related sediment transport and deposition that explains some variations of
those incised-valley fills with respect to the previously published general
models.


title: On polytopes associated to factorisations of prime-powers

abstract:
  We study polytopes associated to factorisations of prime powers. These
polytopes have explicit descriptions either in terms of their vertices or as
intersections of closed halfspaces associated to their facets. We give formulae
for their $f-$vectors.


title: Quantum dynamics in a camel-back potential of a dc SQUID

abstract:
  We investigate the quantum dynamics of a quadratic-quartic anharmonic
oscillator formed by a potential well between two potential barriers. We
realize this novel potential shape with a superconducting circuit comprised of
a loop interrupted by two Josephson junctions, with near-zero current bias and
flux bias near half a flux quantum. We investigate escape out of the central
well, which can occur via tunneling through either of the two barriers, and
find good agreement with a generalized double-path macroscopic quantum
tunneling theory. We also demonstrate that this system exhibits an "optimal
line" in current and flux bias space along which the oscillator, which can be
operated as a phase qubit, is insensitive to decoherence due to low-frequency
current fluctuations.


title: Electronic shell and supershell structure in graphene flakes

abstract:
  We use a simple tight-binding (TB) model to study electronic properties of
free graphene flakes. Valence electrons of triangular graphene flakes show a
shell and supershell structure which follows an analytical expression derived
from the solution of the wave equation for triangular cavity. However, the
solution has different selection rules for triangles with armchair and zigzag
edges, and roughly 40000 atoms are needed to see clearly the first supershell
oscillation. In the case of spherical flakes, the edge states of the zigzag
regions dominate the shell structure which is thus sensitive to the flake
diameter and center. A potential well that is made with external gates cannot
have true bound states in graphene due to the zero energy band gap. However, it
can cause strong resonances in the conduction band.


title: Contour Integral Representations for the Characters of Logarithmic CFTs

abstract:
  We propose a contour integral representation for the one-point correlators at
genus one of the primaries of a family of rational logarithmic conformal field
theories.


title: MARCS model atmospheres

abstract:
  In this review presented at the Symposium A stellar journey in Uppsala, June
2008, I give my account of the historical development of the MARCS code from
the first version published in 1975 and its premises to the 2008 grid. It is
shown that the primary driver for the development team is the science that can
be done with the models, and that they constantly strive to include the best
possible physical data. A few preliminary comparisons of M star model spectra
to spectrophotometric observations are presented. Particular results related to
opacity effects are discussed. The size of errors in the spectral energy
distribution (SED) and model thermal stratification are estimated for different
densities of the wavelength sampling. The number of points used in the MARCS
2008 grid (108000) is large enough to ensure errors of only a few K in all
models of the grid, except the optically very thin layers of metal-poor stars.
Errors in SEDs may reach about 10% locally in the UV. The published sampled
SEDs are thus appropriate to compute synthetic broad-band photometry, but
higher resolution spectra will be computed in the near future and published as
well on the MARCS site (marcs.astro.uu.se). Test model calculations with TiO
line opacity accounted for in scattering show an important cooling of the upper
atmospheric layers of red giants. Rough estimates of radiative and collisional
time scales for electronic transitions of TiO indicate that scattering may well
be the dominant mechanism in these lines. However models constructed with this
hypothesis are incompatible with optical observations of TiO (Arcturus) or IR
observations of OH (Betelgeuse), although they may succeed in explaining H2O
line observations. More work is needed in that direction.


title:
The dynamical origin of the universality classes of spatiotemporal
  intermittency

abstract:
  Studies of the phase diagram of the coupled sine circle map lattice have
identified the presence of two distinct universality classes of spatiotemporal
intermittency viz. spatiotemporal intermittency of the directed percolation
class with a complete set of directed percolation exponents, and spatial
intermittency which does not belong to this class. We show that these two types
of behavior are special cases of a spreading regime where each site can infect
its neighbors permitting an initial disturbance to spread, and a non-spreading
regime where no infection is possible, with the two regimes being separated by
a line, the infection line. The coupled map lattice can be mapped on to an
equivalent cellular automaton which shows a transition from a probabilistic
cellular automaton to a deterministic cellular automaton at the infection line.
The origins of the spreading-non-spreading transition in the coupled map
lattice, as well as the probabilistic to deterministic transition in the
cellular automaton lie in a dynamical phenomenon, an attractor-widening crisis
at the infection line. Indications of unstable dimension variability are seen
in the neighborhood of the infection line. This may provide useful pointers to
the spreading behavior seen in other extended systems.


title:
Quantum Hall effects of graphene with multi orbitals: Topological
  numbers, Boltzmann conductance and Semi-classical quantization

abstract:
  Hall conductance $\sigma_{xy}$ as the Chern numbers of the Berry connection
in the magnetic Brillouin zone is calculated for a realistic multi band
tight-band model of graphene with non-orthogonal basis. It is confirmed that
the envelope of $\sigma_{xy}$ coincides with a semi-classical result when
magnetic field is sufficiently small.
  The Hall resistivity $\rho_{xy}$ from the weak-field Boltzmann theory also
explains the overall behaviour of the $\sigma_{xy}$ if the Fermi surface is
composed of a single energy band. The plateaux of $\sigma_{xy}$ are explained
from semi-classical quantization and necessary modification is proposed for the
Dirac fermion regimes.


title:
Finite-Temperature N\'eel Ordering of Fluctuations in a Plaquette
  Orbital Model

abstract:
  We present a pseudospin model which should be experimentally accessible using
solid-state devices and, being a variation on the compass model, adds to the
toolbox for the protection of qubits in the area of quantum information. Using
Monte Carlo methods, we find for both classical and quantum spins in two and
three dimensions Ising-type Neel ordering of energy fluctuations at finite
temperatures without magnetic order. We also readdress the controversy
concerning the stability of the ordered state in the presence of quenched
impurities and present numerical results which are at clear variance with
earlier claims in the literature.


title: Plain Varieties

abstract:
  Algebraic varieties which are locally isomorphic to open subsets of affine
space will be called {\em plain}. Plain varieties are smooth and rational. The
converse is true for curves and surfaces, and unknown in general. It is shown
that plain varieties are stable under blowup in smooth centers.


title:
Successive Phase Transitions in Na_{0.5}CoO_{2} based on the Triangular
  Lattice d-p Model

abstract:
  We investigate the electronic states of the CoO_2 plane in the layered cobalt
oxides Na_{0.5}CoO_{2} using the realistic 11 band d-p model on a
two-dimensional triangular lattice. Effects of the Coulomb interaction on a Co
site: the intra- and inter-orbital direct terms U and U', the exchange coupling
J and the pair-transfer J', are treated within the Hartree-Fock approximation.
It is found that the metallic antiferromagnetism takes place below T_{c1} and,
in addition, the orbital order accompanied by the small charge order takes
place below T_{c2} (< T_{c1}) where the system becomes insulator. The obtained
results are consistent with the successive phase transitions observed in
Na_{0.5}CoO_{2}.


title:
Exclusive measurements for SUSY events with the ATLAS detector at the
  LHC

abstract:
  We present recent work performed in ATLAS on techniques used to reconstruct
the decays of SUSY particles at the LHC. We concentrate on strategies to be
applied to the first fb-1 of LHC data.


title: Fitting the Galaxy Rotation Curves: Strings versus NFW profile

abstract:
  Remarkable fit of galaxy rotation curves is achieved using a simple model
from string theory. The rotation curves of the same group of galaxies are also
fit using dark matter model with the generalized Navarro-Frenk-White profile
for comparison. String model utilizes three free parameters vs five in the dark
matter model. The average chi-squared of the string model fit is 1.649 while
that of the dark matter model is 1.513. The generalized NFW profile fits
marginally better at a price of two more free parameters.


title: Perspective for resonances in p-p collisions with the ALICE detector

abstract:
  The capability of the ALICE detector to reconstruct short-lived resonances
from the very beginning of the LHC p-p program start-up was investigated,
considering about 300,000 minimum bias p-p PYTHIA events at 900 GeV and 10 TeV,
fully reconstructed under the hypothesis of a still misaligned detector. Only
the information from track reconstruction was taken into account and no PID
knowledge was considered. A reliable rho(770) yield estimation was possible in
900 GeV events. Moreover, in 300,000 p-p events at 10 TeV the signal for the
phi-resonance could be extracted. A significance of 9 can be reached if only
resonances with a transverse momentum larger than 1.5 GeV/c are considered.
Moreover, even with this low statistics the phi signal is visible in events
with a multiplicity as high as 100.


title: A 3-local characterization of M_12 and SL_3(3)

abstract:
  We identify the sporadic simple group $\mathrm{M}_{12}$ and the simple group
$\mathrm{SL}_3(3)$ from some part of their 3-local structure and give a graph
theoretic analogue of the resulting theorem.


title: A Fast Impurity Solver Based on Gutzwiller variational approach

abstract:
  A fast impurity solver for the dynamical mean field theory(DMFT) named Two
Mode Approxi- mation (TMA) is proposed based on the Gutzwiller variational
approach, which captures the main features of both the coherent and incoherent
motion of the electrons. The new solver works with real frequency at zero
temperature and it provides directly the spectral function of the electrons. It
can be easily generalized to multi-orbital impurity problems with general
on-site interactions, which makes it very useful in LDA+DMFT. Benchmarks on one
and two band Hubbard models are presented, and the results agree well with
those of Exact Diagonalization (ED).


title:
Form factors in relativistic quantum mechanics: constraints from
  space-time translations

abstract:
  The comparison of form factors calculated from a single-particle current in
different relativistic quantum mechanic approaches evidences tremendous
discrepancies. The role of constraints coming from space-time translations is
considered here with this respect. It is known that invariance under these
translations implies the energy-momentum conservation relation that is usually
assumed to hold globally. Transformations of the current under these
translations, which lead to this result, also imply constraints that have been
ignored so far in relativistic quantum mechanic approaches. An implementation
of these constraints is discussed in the case of a model with two scalar
constituents. It amounts to incorporate selected two-body currents to all
orders in the interaction. Discrepancies for form factors in different
approaches can thus be removed, contributing to restore the equivalence of
different approaches. Results for the standard front-form approach ($q^+=0$)
are found to fulfill the constraints and are therefore unchanged. The relation
with results from a dispersion-relation approach is also made.


title: The nature and evolution of Nova Cygni 2006

abstract:
  AIMS: Nova Cyg 2006 has been intensively observed throughout its full
outburst. We investigate the energetics and evolution of the central source and
of the expanding ejecta, their chemical abundances and ionization structure,
and the formation of dust. METHOD: We recorded low, medium, and/or
high-resolution spectra (calibrated into accurate absolute fluxes) on 39
nights, along with 2353 photometric UBVRcIc measures on 313 nights, and
complemented them with IR data from the literature. RESULTS: The nova displayed
initially the normal photometric and spectroscopic evolution of a fast nova of
the FeII-type. Pre-maximum, principal, diffuse-enhanced, and Orion absorption
systems developed in a normal way. After the initial outburst, the nova
progressively slowed its fading pace until the decline reversed and a second
maximum was reached (eight months later), accompanied by large spectroscopic
changes. Following the rapid decline from second maximum, the nova finally
entered the nebular phase and formed optically thin dust. We computed the
amount of formed dust and performed a photo-ionization analysis of the
emission-line spectrum during the nebular phase, which showed a strong
enrichment of the ejecta in nitrogen and oxygen, and none in neon, in agreement
with theoretical predictions for the estimated 1.0 Msun white dwarf in Nova Cyg
2006. The similarities with the poorly investigated V1493 Nova Aql 1999a are
discussed.


title:
Symmetric Teleparallel Gravity: Some exact solutions and spinor
  couplings

abstract:
  In this paper we elaborate on the symmetric teleparallel gravity (STPG)
written in a non-Riemannian spacetime with nonzero nonmetricity, but zero
torsion and zero curvature. Firstly we give a prescription for obtaining the
nonmetricity from the metric in a peculiar gauge. Then we state that under a
novel prescription of parallel transportation of a tangent vector in this
non-Riemannian geometry the autoparallel curves coincides with those of the
Riemannian spacetimes. Subsequently we represent the symmetric teleparallel
theory of gravity by the most general quadratic and parity conserving
lagrangian with lagrange multipliers for vanishing torsion and curvature. We
show that our lagrangian is equivalent to the Einstein-Hilbert lagrangian for
certain values of coupling coefficients. Thus we arrive at calculating the
field equations via independent variations. Then we obtain in turn conformal,
spherically symmetric static, cosmological and pp-wave solutions exactly.
Finally we discuss a minimal coupling of a spin-1/2 field to STPG.


title: On the linearity of HNN-extensions with abelian base group

abstract:
  We show that an HNN-extension with finitely generated abelian base group is
Z-linear if and only if it is residually finite.


title: Efficient Pattern Matching on Binary Strings

abstract:
  The binary string matching problem consists in finding all the occurrences of
a pattern in a text where both strings are built on a binary alphabet. This is
an interesting problem in computer science, since binary data are omnipresent
in telecom and computer network applications. Moreover the problem finds
applications also in the field of image processing and in pattern matching on
compressed texts. Recently it has been shown that adaptations of classical
exact string matching algorithms are not very efficient on binary data. In this
paper we present two efficient algorithms for the problem adapted to completely
avoid any reference to bits allowing to process pattern and text byte by byte.
Experimental results show that the new algorithms outperform existing solutions
in most cases.


title: Geometrically Derived Timescales for Star Formation in Spiral Galaxies

abstract:
  We estimate a characteristic timescale for star formation in the spiral arms
of disk galaxies, going from atomic hydrogen (HI) to dust-enshrouded massive
stars. Drawing on high-resolution HI data from The HI Nearby Galaxy Survey and
24$\mu$m images from the Spitzer Infrared Nearby Galaxies Survey we measure the
average angular offset between the HI and 24$\mu$m emissivity peaks as a
function of radius, for a sample of 14 nearby disk galaxies. We model these
offsets assuming an instantaneous kinematic pattern speed, $\Omega_p$, and a
timescale, t(HI-->24$\mu$m), for the characteristic time span between the dense
\hi phase and the formation of massive stars that heat the surrounding dust.
Fitting for $\Omega_p$ and t(HI-->24$\mu$m), we find that the radial dependence
of the observed angular offset (of the \hi and 24$\mu$m emission) is consistent
with this simple prescription; the resulting corotation radii of the spiral
patterns are typically $R_{cor}\simeq 2.7 R_{s}$, consistent with independent
estimates. The resulting values of t(HI-->24$\mu$m) for the sample are in the
range 1--4 Myr. We have explored the possible impact of non-circular gas
motions on the estimate of t(HI-->24$\mu$m) and have found it to be
substantially less than a factor of 2. This implies that a short timescale for
the most intense phase of the ensuing star formation in spiral arms, and
implies a considerable fraction of molecular clouds exist only for a few Myr
before forming stars. However, our analysis does not preclude that some
molecular clouds persist considerably longer. If much of the star formation in
spiral arms occurs within this short interval t(HI-->24$\mu$m), then star
formation must be inefficient, in order to avoid the short-term depletion of
the gas reservoir.


title: MHD Memes

abstract:
  The celebration of Allan Kaufman's 80th birthday was an occasion to reflect
on a career that has stimulated the mutual exchange of ideas (or memes in the
terminology of Richard Dawkins) between many researchers. This paper will
revisit a meme Allan encountered in his early career in magnetohydrodynamics,
the continuation of a magnetohydrodynamic mode through a singularity, and will
also mention other problems where Allan's work has had a powerful
cross-fertilizing effect in plasma physics and other areas of physics and
mathematics.

categories: physics.plasm-ph math-ph math.CA math.MP physics.hist-ph


title: Abstract Hodge decomposition and minimal models for cyclic algebras

abstract:
  We show that an algebra over a cyclic operad supplied with an additional
linear algebra datum called Hodge decomposition admits a minimal model whose
structure maps are given in terms of summation over trees. This minimal model
is unique up to homotopy.


title: The statistical origins of quantum mechanics

abstract:
  It is shown that Schroedinger's equation may be derived from three
postulates. The first is a kind of statistical metamorphosis of classical
mechanics, a set of two relations which are obtained from the canonical
equations of particle mechanics by replacing all observables by statistical
averages. The second is a local conservation law of probability with a
probability current which takes the form of a gradient. The third is a
principle of maximal disorder as realized by the requirement of minimal Fisher
information. The rule for calculating expectation values is obtained from a
fourth postulate, the requirement of energy conservation in the mean. The fact
that all these basic relations of quantum theory may be derived from premises
which are statistical in character is interpreted as a strong argument in favor
of the statistical interpretation of quantum mechanics. The structures of
quantum theory and classical statistical theories are compared and some
fundamental differences are identified.


title:
Presentation of right-angled Soergel categories by generators and
  relations

abstract:
  Soergel bimodule category B is a categorification of the Hecke algebra of a
Coxeter system (W,S). We find a presentation of B (as a tensor category) by
generators and relations when W is a right-angled Coxeter group.


title: Searches at the Tevatron for a Low Mass Standard Model Higgs Boson

abstract:
  We report on searches for the standard model Higgs boson with the CDF and D0
detectors using up to 2.7 fb$^{-1}$ of $\sqrt s=$ 1.96 TeV proton anti-proton
collisions at Fermilab's Tevatron. We focus on analyses that are sensitive to
low mass Higgs production with $m_H<$ 140 GeV/$c^2$ favored by precision
electroweak constraints. Both CDF and D0 find no evidence for Higgs boson
production, and set upper limits on cross section times branching ratio.
Several analyses improvements have increased the sensitivity to a Higgs signal
faster than what is expected from increasing datasets alone.


title:
On a class of multidimensional integrable hierarchies and their
  reductions

abstract:
  A class of multidimensional integrable hierarchies connected with commutation
of general (unreduced) (N+1)-dimensional vector fields containing derivative
over spectral variable is considered. They are represented in the form of
generating equation, as well as in the Lax-Sato form. A dressing scheme based
on nonlinear vector Riemann problem is presented for this class. The
hierarchies connected with Manakov-Santini equation and Dunajski system are
considered as illustrative examples.


title: W-types in sheaves

abstract: We give a concrete description of W-types in categories of sheaves.


title: Connecting spin and statistics in quantum mechanics

abstract:
  The spin-statistics connection is derived in a simple manner under the
postulates that the original and the exchange wave functions are simply added,
and that the azimuthal phase angle, which defines the orientation of the spin
part of each single-particle spin-component eigenfunction in the plane normal
to the spin-quantization axis, is exchanged along with the other parameters.
The spin factor (-1)^2s belongs to the exchange wave function when this
function is constructed so as to get the spinor ambiguity under control. This
is achieved by effecting the exchange of the azimuthal angle by means of
rotations and admitting only rotations in one sense. The procedure works in
Galilean as well as in Lorentz-invariant quantum mechanics. Relativistic
quantum field theory is not required.


title: Infrared spectroscopy of electronic bands in bilayer graphene

abstract:
  We present infrared spectra (0.1-1 eV) of electrostatically gated bilayer
graphene as a function of doping and compare it with tight binding
calculations. All major spectral features corresponding to the expected
interband transitions are identified in the spectra: a strong peak due to
transitions between parallel split-off bands and two onset-like features due to
transitions between valence and conduction bands. A strong gate voltage
dependence of these structures and a significant electron-hole asymmetry is
observed that we use to extract several band parameters. Surprisingly, the
structures related to the gate-induced bandgap are much less pronounced in the
experiment than predicted by the tight binding model.


title: Radiative and Leptonic B-meson Decays from the B-factories

abstract:
  Radiative and leptonic decays of B-mesons represent an excellent laboratory
for the search for New Physics. I present here recent results on radiative and
leptonic decays from the Belle and BABAR collaborations.


title: Toward a classification of prime ideals in Pr\"ufer domains

abstract:
  The primary purpose of this paper is give a classification scheme for the
nonzero primes of a Pr\"ufer domain based on five properties. A prime $P$ of a
Pr\"ufer domain $R$ could be sharp or not sharp, antesharp or not, divisorial
or not, branched or unbranched, idempotent or not. Based on these five basic
properties, there are six types of maximal ideals and twelve types of
nonmaximal (nonzero) primes. Both characterizations and examples are given for
each type that exists.


title:
Competition and fragmentation: a simple model generating lognormal-like
  distributions

abstract:
  The current distribution of language size in terms of speaker population is
generally described using a lognormal distribution. Analyzing the original real
data we show how the double-Pareto lognormal distribution can give an
alternative fit that indicates the existence of a power law tail. A simple
Monte Carlo model is constructed based on the processes of competition and
fragmentation. The results reproduce the power law tails of the real
distribution well and give better results for a poorly connected topology of
interactions.


title: General Relativity on Random Operators

abstract:
  We present a mathematical structure which unifies mathematical structures of
general relativity and quantum mechanics. It consists of the noncommutative
algebra of compactly supported, complex valued functions ${\mathcal A}$, with
convolution as multiplication, on a groupoid $\Gamma $ the base of which is the
total space $E$ of the frame bundle over space-time $M$. A differential
geometry based on derivations of ${\mathcal A}$ suitably generalizes the
standard differential geometry of space-time, and the algebra ${\mathcal A}$,
when represented in a bundle of Hilbert spaces, defines a von Neumann algebra
${\mathcal M}$ of random operators that generalizes the usual quantum
mechanics. The main result of the present paper is that there exists a space
${\mathcal M_0}$, dense in ${\mathcal M}$, that is isomorphic with the algebra
${\mathcal A}$. This isomorphism allows us to transfer all differentially
geometric constructions, generalized Einstein's equations including, made with
the help of ${\mathcal A}$ (and its derivations) to the space ${\mathcal M_0}$.
In this way, we obtain a generalization of general relativity in terms of
random operators on a bundle of Hilbert spaces. However, this generalization
cannot be extended to the whole of ${\mathcal M}$, and this is the main
mathematical obstacle, at least in this approach, to fully unify theory of
gravity with physics of quanta.


title:
Nonlinear perturbations of cosmological scalar fields with non-standard
  kinetic terms

abstract:
  We adopt a covariant formalism to derive exact evolution equations for
nonlinear perturbations, in a universe dominated by two scalar fields. These
scalar fields are characterized by non-canonical kinetic terms and an arbitrary
field space metric, a situation typically encountered in inflationary models
inspired by string theory. We decompose the nonlinear scalar perturbations into
adiabatic and entropy modes, generalizing the definition adopted in the linear
theory, and we derive the corresponding exact evolution equations. We also
obtain a nonlinear generalization of the curvature perturbation on uniform
density hypersurfaces, showing that on large scales it is sourced only by the
nonlinear version of the entropy perturbation. We then expand these equations
to second order in the perturbations, using a coordinate based formalism. Our
results are relatively compact and elegant and enable one to identify the new
effects coming from the non-canonical structure of the scalar fields
Lagrangian. We also explain how to analyze, in our formalism, the interesting
scenario of multifield Dirac-Born-Infeld inflation.


title: Time-resolved charge detection with cross-correlation techniques

abstract:
  We present time-resolved charge sensing measurements on a GaAs double quantum
dot with two proximal quantum point contact (QPC) detectors. The QPC currents
are analyzed with cross-correlation techniques, which enables us to measure dot
charging and discharging rates for significantly smaller signal-to-noise ratios
than required for charge detection with a single QPC. This allows to reduce the
current level in the detector and therefore the invasiveness of the detection
process and may help to increase the available measurement bandwidth in
noise-limited setups.


title:
A new standard: Age and distance for the open cluster NGC 6791 from the
  eclipsing binary member V20

abstract:
  The detached eclipsing binary V20 in the old, metal--rich open cluster NGC
6791 is studied in order to determine highly accurate masses and radii of its
components. This allows the cluster age to be established with high precision,
using isochrones in the mass-radius diagram. We employ high-resolution UVES
spectroscopy of V20 to determine the spectroscopic orbit and time-series V, I
photometry to obtain the photometric elements. The masses and radii of the V20
components are found to be1.074+/-0.008Msun and 1.399+/-0.016Rsun (primary) and
0.827+/-0.004Msun and 0.768+/-0.006Rsun (secondary). The primary is located
almost exactly at the hottest point along the cluster isochrone, and the
secondary is a ~7 times fainter main--sequence star. We determine an apparent
cluster distance-modulus of (m-M)_V = 13.46+/-0.10 (average of primary and
secondary). The cluster age is obtained from comparisons with theoretical
isochrones in the mass--radius diagram. Using the isochrones from
Victoria--Regina with [Fe/H] =+0.37 we find 7.7+/-0.5Gyr, whereas the
Yonsei-Yale (Y2) isochrones lead to 8.2+/-0.5Gyr, and BaSTI isochrones to
9.0+/-0.5Gyr. In a mass-radius diagram, the 7.7Gyr VRSS and 9.0Gyr BaSTI
isochrones overlap nearly perfectly despite the age-difference. This model
dependence, which is significantly larger than the precision determined from
mass, radius, and abundance uncertainties, prevents a definitive
age-determination of the cluster. By observing a suitable number of detached
eclipsing binaries in several open clusters it should be possible to calibrate
the age--scale and provide firm constraints which stellar models must
reproduce. (abridged)


title: A new continuum limit of matrix models

abstract:
  We define a new scaling limit of matrix models which can be related to the
method of causal dynamical triangulations (CDT) used when investigating
two-dimensional quantum gravity. Surprisingly, the new scaling limit of the
matrix models is also a matrix model, thus explaining why the recently
developed CDT continuum string field theory (arXiv:0802.0719) has a
matrix-model representation (arXiv:0804.0252).


title: Graded Brauer Tree Algebras

abstract:
  In this paper we construct non-negative gradings on a basic Brauer tree
algebra $A_{\Gamma}$ corresponding to an arbitrary Brauer tree $\Gamma$ of type
$(m,e)$. We do this by transferring gradings via derived equivalence from a
basic Brauer tree algebra $A_S$, whose tree is a star with the exceptional
vertex in the middle, to $A_{\Gamma}$. The grading on $A_S$ comes from the
tight grading given by the radical filtration. To transfer gradings via derived
equivalence we use tilting complexes constructed by taking Green's walk around
$\Gamma$ (cf. [\ref{Zak}]). By computing endomorphism rings of these tilting
complexes we get graded algebras.
  We also compute ${\rm Out}^K(A_{\Gamma})$, the group of outer automorphisms
that fix isomorphism classes of simple $A_{\Gamma}$-modules, where $\Gamma$ is
an arbitrary Brauer tree, and we prove that there is unique grading on
$A_{\Gamma}$ up to graded Morita equivalence and rescaling.


title:
Field induced magnetic order in the frustrated magnet Gadolinium Gallium
  Garnet

abstract:
  Gd3Ga5O12, (GGG), has an extraordinary magnetic phase diagram, where no long
range order is found down to 25 mK despite \Theta_CW \approx 2 K. However, long
range order is induced by an applied field of around 1 T. Motivated by recent
theoretical developments and the experimental results for a closely related
hyperkagome system, we have performed neutron diffraction measurements on a
single crystal sample of GGG in an applied magnetic field. The measurements
reveal that the H-T phase diagram of GGG is much more complicated than
previously assumed. The application of an external field at low T results in an
intensity change for most of the magnetic peaks which can be divided into three
distinct sets: ferromagnetic, commensurate antiferromagnetic, and
incommensurate antiferromagnetic. The ferromagnetic peaks (e.g. (112), (440)
and (220)) have intensities that increase with the field and saturate at high
field. The antiferromagnetic reflections have intensities that grow in low
fields, reach a maximum at an intermediate field (apart from the (002) peak
which shows two local maxima) and then decrease and disappear above 2 T. These
AFM peaks appear, disappear and reach maxima in different fields. We conclude
that the competition between magnetic interactions and alternative ground
states prevents GGG from ordering in zero field. It is, however, on the verge
of ordering and an applied magnetic field can be used to crystallise ordered
components. The range of ferromagnetic and antiferromagnetic propagation
vectors found reflects the complex frustration in GGG.


title: Elastic theory of unconstrained non-Euclidean plates

abstract:
  Non-Euclidean plates are a subset of the class of elastic bodies having no
stress-free configuration. Such bodies exhibit residual stress when relaxed
from all external constraints, and may assume complicated equilibrium shapes
even in the absence of external forces. In this work we present a mathematical
framework for such bodies in terms of a covariant theory of linear elasticity,
valid for large displacements. We propose the concept of non-Euclidean plates
to approximate many naturally formed thin elastic structures. We derive a thin
plate theory, which is a generalization of existing linear plate theories,
valid for large displacements but small strains, and arbitrary intrinsic
geometry. We study a particular example of a hemispherical plate. We show the
occurrence of a spontaneous buckling transition from a stretching dominated
configuration to bending dominated configurations, under variation of the plate
thickness.


title: Clifford Algebra with Mathematica

abstract:
  The Clifford algebra of a n-dimensional Euclidean vector space provides a
general language comprising vectors, complex numbers, quaternions, Grassman
algebra, Pauli and Dirac matrices. In this work, we present an introduction to
the main ideas of Clifford algebra, with the main goal to develop a package for
Clifford algebra calculations for the computer algebra program Mathematica. The
Clifford algebra package is thus a powerful tool since it allows the
manipulation of all Clifford mathematical objects. The package also provides a
visualization tool for elements of Clifford Algebra in the 3-dimensional space.
clifford.m is available from github.com/jlaragonvera/Geometric-Algebra


title:
Scanning tunneling microscopy and kinetic Monte Carlo investigation of
  Cesium superlattices on Ag(111)

abstract:
  Cesium adsorption structures on Ag(111) were characterized in a
low-temperature scanning tunneling microscopy experiment. At low coverages,
atomic resolution of individual Cs atoms is occasionally suppressed in regions
of an otherwise hexagonally ordered adsorbate film on terraces. Close to step
edges Cs atoms appear as elongated protrusions along the step edge direction.
At higher coverages, Cs superstructures with atomically resolved hexagonal
lattices are observed. Kinetic Monte Carlo simulations model the observed
adsorbate structures on a qualitative level.


title:
On the level of background in underground muon measurements with plastic
  scintillator counters

abstract:
  In this short note we present results of background measurements carried out
with a polystyrene based cast plastic 12.0x12.0x3.0 cm^3 size scintillator
counter with a wavelength shifting fibre and a multi-pixel Geiger mode
avalanche photodiode readout in the Baksan underground laboratory at a depth of
200 meters of water equivalent. The total counting rate of the scintillator
counter measured at this depth and at a threshold corresponding to ~0.37 of a
minimum ionizing particle is approximately 1.3 Hz.


title: Piezoelectric exciton-acoustic phonon coupling in single quantum dots

abstract:
  Micro-photoluminescence spectroscopy at variable temperature, excitation
intensity and energy was performed on a single InAs/AlAs self-assembled quantum
dot. The exciton emission line (zero-phonon line, ZPL) exhibits a broad
sideband due to exciton-acoustic phonon coupling by the deformation potential
mechanism. Additionally, narrow low-energy sidebands at about 0.25 meV of the
ZPL are attributed to exciton-acoustic phonon piezoelectric coupling. In
lowering the excitation energy or intensity these bands gradually dominate the
emission spectrum of the quantum dot while the ZPL disappears. At high
excitation intensity the sidebands due to piezoelectric coupling decrease
strongly and the ZPL dominates the spectrum as a consequence of screening of
the piezoelectric coupling by the photocreated free carriers.


title: Linear wave propagation in relativistic magnetohydrodynamics

abstract:
  The properties of linear Alfv\'en, slow, and fast magnetoacoustic waves for
uniform plasmas in relativistic magnetohydrodynamics (MHD) are discussed,
augmenting the well-known expressions for their phase speeds with knowledge on
the group speed. A 3+1 formalism is purposely adopted to make direct comparison
with the Newtonian MHD limits easier and to stress the graphical representation
of their anisotropic linear wave properties using the phase and group speed
diagrams. By drawing these for both the fluid rest frame and for a laboratory
Lorentzian frame which sees the plasma move with a three-velocity having an
arbitrary orientation with respect to the magnetic field, a graphical view of
the relativistic aberration effects is obtained for all three MHD wave
families. Moreover, it is confirmed that the classical Huygens construction
relates the phase and group speed diagram in the usual way, even for the lab
frame viewpoint. Since the group speed diagrams correspond to exact solutions
for initial conditions corresponding to a localized point perturbation, their
formulae and geometrical construction can serve to benchmark current
high-resolution algorithms for numerical relativistic MHD.


title:
Quantum information transfer from spin to orbital angular momentum of
  photons

abstract:
  The optical "spin-orbit" coupling occurring in a suitably patterned
nonuniform birefringent plate known as `q-plate' allows entangling the
polarization of a single photon with its orbital angular momentum (OAM). This
process, in turn, can be exploited for building a bidirectional "spin-OAM
interface", capable of transposing the quantum information from the spin to the
OAM degree of freedom of photons and \textit{vice versa}. Here, we
experimentally demonstrate this process by single-photon quantum tomographic
analysis. Moreover, we show that two-photon quantum correlations such as those
resulting from coalescence interference can be successfully transferred into
the OAM degree of freedom.


title:
Magnetic Field Induced Instabilities in Localised Two-Dimensional
  Electron Systems

abstract:
  We report density dependent instabilities in the localised regime of
mesoscopic two-dimensional electron systems (2DES) with intermediate strength
of background disorder. They are manifested by strong resistance oscillations
induced by high perpendicular magnetic fields B_{\perp}. While the amplitude of
the oscillations is strongly enhanced with increasing B_{\perp}, their position
in density remains unaffected. The observation is accompanied by an unusual
behaviour of the temperature dependence of resistance and activation energies.
We suggest the interplay between a strongly interacting electron phase and the
background disorder as a possible explanation.


title: A new computational approach to lattice quantum field theories

abstract:
  Developments in algorithms over the past decade suggest that there is a new
computational approach to a class of quantum field theories. This approach is
based on rewriting the partition function in a representation similar to the
world-line representation and hence we shall call it the "WL-approach". This
approach is likely to be more powerful than the conventional approach in some
regions of parameter space, especially in the presence of chemical potentials
or massless fermions. While world-line representations are natural in the
Hamiltonian formulation, they can also be constructed directly in Euclidean
space. We first describe the approach and its advantages by considering the
classical XY model in the presence of a chemical potential. We then argue that,
$CP^{N-1}$ models, models of pions on the lattice and the lattice massless
Thirring model, can all be formulated and solved using the WL-approach. In
particular, we discover that the WL-approach to the Thirring model leads to a
novel determinantal Monte-Carlo algorithm which we call the "dynamical-bag"
algorithm. Finally, we argue that a simple extension of the WL-approach to
gauge theories leads to a world-sheet, "WS-approach", in Abelian Lattice Gauge
theory.


title: On the rapid TeV flaring activity of Markarian 501

abstract:
  Aims: We investigate the one-zone SSC model of TeV blazars in the presence of
electron acceleration. In this picture electrons reach a maximum energy where
acceleration saturates from a combination of synchrotron and inverse Compton
scattering losses. Methods: We solve the spatially averaged kinetic equations
which describe the simultaneous evolution of particles and photons, obtaining
the multi-wavelength spectrum as a function of time. Results: We apply the
model to the rapid flare of Mrk 501 of July 9, 2005 as this was observed by the
MAGIC telescope and obtain the relevant parameters for the pre-flare quasi
steady state and the ones during the flare. We show that a hard lag flare can
be obtained with parameters which lie well within the range already accepted
for this source. Especially the choice of a high value of the Doppler factor
seems to be necessary.