title: Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 6782

abstract:
  NGC 6782 is an early-type barred spiral galaxy exhibiting a rich and complex
morphology with multiple ring patterns. To provide a physical understanding of
its structure and kinematical properties, two-dimensional hydrodynamical
simulations have been carried out. Numerical calculations reveal that the
striking features in NGC 6782 can be reproduced provided that the gas flow is
governed by the gravitational potential associated with a slowly rotating
strong bar. In particular, the response of the gaseous disk to the bar
potential leads to the excitation of spiral density waves at the inner Lindblad
resonance giving rise to the appearance of a nearly circular nuclear ring with
a pair of dust lanes. For a sufficiently strong bar potential, the inner 4:1
spiral density waves are also excited. The interaction of the higher harmonic
waves with the waves excited at the inner Lindblad resonance and confined by
the outer Lindblad resonance results in the observed diamond-shaped (or pointy
oval) inner ring structure. The overall gas morphology and kinematical features
are both well reproduced by the model provided that the pattern speed of the
bar is $\sim 25$ km s$^{-1}$ kpc$^{-1}$.


title:
Asymptotic behavior of smooth solutions for partially dissipative
  hyperbolic systems with a convex entropy

abstract:
  We study the asymptotic time behavior of global smooth solutions to general
entropy dissipative hyperbolic systems of balance law in m space dimensions,
under the Shizuta-Kawashima condition. We show that these solutions approach
constant equilibrium state in the Lp-norm at a rate O(t^(-m/2(1-1/p))), as t
tends to $\infty$, for p in [min (m,2),+ \infty]. Moreover, we can show that we
can approximate, with a faster order of convergence, theconservative part of
the solution in terms of the linearized hyperbolic operator for m >= 2, and by
a parabolic equation in the spirit of Chapman-Enskog expansion. The main tool
is given by a detailed analysis of the Green function for the linearized
problem.


title: Modeling real spatial networks

abstract:
  We have studied transportation network, namely a road network of the Moscow
region and airline network of the Russian Federation. We have constructed
corresponding networks and studied degree distribution and length distribution
for these networks, as well as the dependences on the average clustering
coefficients and the nearest neighbours average degree as a function of the
vertex degree. In conclusion we discuss degree and length distributions in the
framework of the nonextensive statistics, using the maximum entropy approach
and the model with additive and multiplicative noise. We present a procedure of
fitting the results of the data processing to the q-type distribution which
allows the fractal dimension definition of the networks under study.


title:
Simultaneous realization of function space structures in transitive
  Banach spaces

abstract:
  This paper has been withdrawn, since it contains a corollary with impossible
consequences and the source of an error is currently unknown.


title: Spin filtering by a periodic nanospintronic devices

abstract:
  For a linear chain of diamond-like elements, we show that the Rashba
spin-orbit interaction (which can be tuned by a perpendicular gate voltage) and
the Aharonov-Bohm flux (due to a perpendicular magnetic field) can combine to
select only one propagating ballistic mode, for which the electronic spins are
fully polarized along a direction that can be tuned by the electric and
magnetic fields and by the electron energy. All the other modes are evanescent.
For a wide range of parameters, this chain can serve as a spin filter.


title:
Two-phase flow model for energetic proton beam induced pressure waves in
  mercury target systems in the planned European Spallation Source

abstract:
  Two-phase flow calculations are presented to investigate the
thermo-hydraulical effects of the interaction between 300 kJ proton pulses (2
ms long, 1.3 GeV) with a closed mercury loop which can be considered as a model
system of the target of the planned European Spallation Source(ESS) facility.
The two-fluid model consists of six first-order partial differential equations
that present one dimensional mass momentum and energy balances for mercury
vapour and liquid phases are capable to describe quick transients like
cavitation effects or shock waves. The absorption of the proton beam is
represented as instantaneous heat source in the energy balance equations.
Densities and internal energies of the mercury liquid-vapour system are
calculated from van der Waals equation, and the general method how to obtain
such properties is also presented. A second order accurate high-resolution
shock-capturing numerical scheme is applied with different kinds of limiters in
the numerical calculations. %Our two-fluid model is very similar to the RELAP5
thermo-hydraulical code %which is used in the nuclear industry to simulate
nuclear power plant accidents. Our analysis show that even 75 degree
temperature heat shocks cannot cause considerable cavitation effects in mercury
in 2ms long pulses


title:
Universal Extra Dimensions, Radiative Returns and the Inverse Problem at
  a Linear e+e- Collider

abstract:
  In a five-dimensional model with one Universal Extra Dimension (UED), signals
for a pair of n = 1 Kaluza-Klein excitations could be easily observed at a
future e+ e- collider if the process in question is kinematically allowed.
However, these signals would prove difficult to distinguish from those
predicted in other models, such as those with an extended gauge symmetry or
supersymmetry. A much better power of discrimination is provided by the fact
that the same machine could also produce the n=2 gauge bosons \gamma_2 and Z_2
as resonances in fermion pair-production without any upgrade in the collision
energy \sqrt{s}. Assuming a fixed \sqrt{s}, as is expected at upcoming e+e-
machines, we investigate the role of beam radiation in helping to excite such
resonances through radiative returns. We then show how these resonances can
yield unambiguous signals for UED, if taken in conjunction with the production
of Z_1 pairs, identified by their decays to leptons and missing transverse
energy.


title: On the Cluster Size Distribution for Percolation on Some General Graphs

abstract:
  We show that for any Cayley graph, the probability (at any $p$) that the
cluster of the origin has size n decays at a well-defined exponential rate
(possibly 0). For general graphs, we relate this rate being positive in the
supercritical regime with the amenability/nonamenability of the underlying
graph.


title:
Algebraic cycles on the relative symmetric powers and on the relative
  Jacobian of a family of curves. II

abstract:
  Let C be a curve over a non-singular base variety S. We study algebraic
cycles on the symmetric powers C^[n] and on the Jacobian J. The Chow homology
of C^[*], the sum of all C^[n], is a ring using the Pontryagin product. We
prove that this ring is isomorphic to CH(J)[t]<u>, the PD-polynomial algebra
(variable: u) over the usual polynomial ring (variable: t) over the Chow ring
CH(J). We give two such isomorphisms that over a general base are different.
Further we give some precise results on how CH(J) sits embedded in CH(C^[*])
and we give an explicit geometric description of how the derivations with
regard to t and u act.
  Our results give rise to a new grading on the Chow ring of the Jacobian.
After tensoring with Q the associated descending filtration coincides with the
one coming from Beauville's decomposition. The grading we obtain is in general
different from Beauville's.
  Finally we give a version of our main result for tautological classes, and we
show how our methods give a very simple and geometric proof of some relations
obtained by Herbaut and van der Geer-Kouvidakis.


title: Magnetic barrier induced conductance fluctuations in quantum wires

abstract:
  Quasi-ballistic semiconductor quantum wires are exposed to localized
perpendicular magnetic fields, also known as magnetic barriers. Pronounced,
reproducible conductance fluctuations as a function of the magnetic barrier
amplitude are observed. The fluctuations are strongly temperature dependent and
remain visible up to temperatures of about 10 K. Simulations based on recursive
Green functions suggest that the conductance fluctuations originate from
parametric interferences of the electronic wave functions which experience
scattering between the magnetic barrier and the electrostatic potential
landscape.


title:
High order radiative corrections for unpolarized electron proton elastic
  scattering at low $Q^2$

abstract:
  We investigate the effect of high order radiative corrections in unpolarized
electron proton elastic scattering and compare with the calculations at lowest
order, which are usually applied to experimental data. We show that higher
order terms play a role, starting from values of the momentum transfer squared,
$Q^2$, larger than the electron mass. Particular attention is devoted to the
$\epsilon$ dependence of radiative corrections.


title:
Review of searches for Higgs bosons and beyond the standard model
  physics at the Tevatron

abstract:
  The energy frontier is currently at the Fermilab Tevatron accelerator, which
collides protons and antiprotons at a center-of-mass energy of 1.96 TeV. The
luminosity delivered to the CDF and D0 experiments has now surpassed the 4
fb-1. This paper reviews the most recent direct searches for Higgs bosons and
beyond-the-standard-model (BSM) physics at the Tevatron. The results reported
correspond to an integrated luminosity of up to 2.5 fb-1 of Run II data
collected by the two Collaborations. Searches covered include: the standard
model (SM) Higgs boson (including sensitivity projections), the neutral Higgs
bosons in the minimal supersymmetric extension of the standard model (MSSM),
charged Higgs bosons and extended Higgs models, supersymmetric decays that
conserve or violate R-parity, gauge-mediated supersymmetric breaking models,
long-lived particles, leptoquarks, compositeness, extra gauge bosons, extra
dimensions, and finally signature-based searches. Given the excellent
performance of the collider and the continued productivity of the experiments,
the Tevatron physics potential looks promising for discovery with the coming
larger data sets. In particular, evidence for the SM Higgs boson could be
obtained if its mass is light or near 160 GeV. The observed (expected) upper
limits are currently a factor of 3.7 (3.3) higher than the expected SM Higgs
boson cross section at m_H=115 GeV and 1.1 (1.6) at m_H=160 GeV at 95% C.L.


title: Exchange Symmetry and Multipartite Entanglement

abstract:
  Entanglement of multipartite systems is studied based on exchange symmetry
under the permutation group S_N. With the observation that symmetric property
under the exchange of two constituent states and their separability are
intimately linked, we show that anti-symmetric (fermionic) states are
necessarily globally entangled, while symmetric (bosonic) states are either
globally entangled or fully separable and possess essentially identical states
in all the constituent systems. It is also shown that there cannot exist a
fully separable state which is orthogonal to all symmetric states, and that
full separability of states does not survive under total symmetrization unless
the states are originally symmetric. Besides, anyonic states permitted under
the braid group B_N should also be globally entangled. Our results reveal that
exchange symmetry is actually sufficient for pure states to become globally
entangled or fully separable.


title:
Method of Linear Invariants for description of beam dynamics of FEL
  undulator

abstract:
  We propose a new model for description of electrons beam dynamics in Free
Electron Laser (FEL) undulator, based on the method of linear time-dependent
invariants of quantum-mechanical charge particle. The magnetic field has
periodic structure along the undulator. For this problem, described by
time-dependent quadratic Hamiltonian, we obtain exact solution. The
time-evolutions of the tree quantum fluctuations: covariance cov(q,p), var(q)
and var(p) for the charge particle in this case are also determined. This
research will help to optimize the FEL undulator: for example, using a 2.5 GeV
linear electron accelerator it will be possible to emit radiation at 1.5 nm and
shorter length.
  This method could be applicable also to any device with periodic structure of
applied field (e.g. Tokamak, cyclic accelerators) for the case of charge
non-relativistic quantum particles.


title: Self-dual Maxwell field in 3D gravity with torsion

abstract:
  We study the system of self-dual Maxwell field coupled to 3D gravity with
torsion, with Maxwell field modified by a topological mass term. General
structure of the field equations reveals a new, dynamical role of the classical
central charges, and gives a simple correspondence between self-dual solutions
with torsion and their Riemannian counterparts. We construct two exact
self-dual solutions, corresponding to the sectors with massless and massive
Maxwell field, and calculate their conserved charges.


title:
On the nuclear interaction. Potential, binding energy and fusion
  reaction

abstract:
  The nuclear interaction is responsible for keeping neutrons and protons
joined in an atomic nucleus. Phenomenological nuclear potentials, fitted to
experimental data, allow one to know about the nuclear behaviour with more or
less success where quantum mechanics is hard to be used. A nuclear potential is
suggested and an expression for the potential energy of two nuclear entities,
either nuclei or nucleons, is developed. In order to estimate parameters in
this expression, some nucleon additions to nuclei are considered and a model is
suggested as a guide of the addition process. Coulomb barrier and energy for
the addition of a proton to each one of several nuclei are estimated by taking
into account both the nuclear and electrostatic components of energy. Studies
on the binding energies of several nuclei and on the fusion reaction of two
nuclei are carried out.


title: Experimental quantum key distribution based on a Bell test

abstract:
  We report on a complete free-space field implementation of a modified Ekert91
protocol for quantum key distribution using entangled photon pairs. For each
photon pair we perform a random choice between key generation and a Bell
inequality. The amount of violation is used to determine the possible knowledge
of an eavesdropper to ensure security of the distributed final key.


title: Riemannian products which are conformally equivalent to Einstein metrics

abstract:
  Necessary and sufficient conditions for a Riemannian product to be
conformally equivalent to an Einstein manifold are given. Such spaces which are
complete are characterized.


title: On Caccetta-Haggkvist Conjecture

abstract:
  We show that we cannot avoid the existence of at least one directed circuit
of length less than or equal to (n/r) in a digraph on n vertices with
out-degree greater than or equal to r. This is well-known Caccetta-Haggkvist
problem.


title: Testing the EPR Locality using B-Mesons

abstract:
  We study the possibility of testing local realistic theory (LRT), envisioned
implicitly by Einstein, Podolsky and Rosen in 1935, based on the Bell
inequality for the correlations in the decay modes of entangled K or B-mesons.
It is shown that such a test is possible for a restricted class of LRT, despite
the passive nature of decay events and/or the non-unitary treatment of the
correlations which invalidate the test for general LRT. Unfortunately, the
present setup of the KEKB (Belle) experiment, where the coherence of entangled
B-mesons has been confirmed recently, does not admit such a test due to the
inability of determining the decay times of the entangled pairs separately. The
indeterminacy also poses a problem for ensuring the locality of the test,
indicating that improvement to resolve the indeterminacy is crucial for the
test of LRT.


title: Leray-alpha simulations of wall-bounded turbulent flows

abstract:
  The Leray-$\alpha$ model reduces the range of active scales of the
Navier-Stokes equations by smoothing the advective transport. Here we assess
the potential of the Leray-$\alpha$ model in its standard formulation to
simulate wall-bounded flows. Three flow cases are considered: plane channel
flow at $\Re_\tau=590$, Rayleigh-B\'{e}nard convection at $\Ra=10^7$ and
$\Pr=1$, and a side-heated vertical channel at $\Ra=5 \times 10^6$ and
$\Pr=0.7$. The simulations are compared to results from a well resolved and
coarse DNS. It is found that for all three flow cases, the variance in the
velocity field increases as the filter width parameter $a$ is increased, where
$a$ is connected to the filter width as $\alpha_i = a \Delta x_i$, with $\Delta
x_i$ the local grid size. Furthermore, the viscous and diffusive wall regions
tend to thicken relative to the coarse DNS results as a function of $a$. In the
cases where coarse DNS overpredicts wall gradients (as for Rayleigh-B\'{e}nard
convection and the side-heated vertical channel), the thickening is beneficial.
However, for the plane channel flow, coarse DNS underpredicts the wall-shear
velocity, and increasing $a$ only degrades the results. It is shown that
buoyancy effects need to be included with care, because of the close relation
of turbulent heat flux and the production of turbulent kinetic energy.


title: Stellar jets

abstract:
  With a goal of understanding the conditions under which jets might be
produced in novae and related objects, I consider the conditions under which
jets are produced from other classes of accreting compact objects. I give an
overview of accretion disk spectral states, including a discussion of in which
states these jets are seen. I highlight the differences between neutron stars
and black holes, which may help give us insights about when and how the
presence of a solid surface may help or inhibit jet production.


title: Charge ordering and magnetism in quarter-filled Hubbard-Holstein model

abstract:
  We study a two-dimensional Hubbard-Holstein model with phonons treated in the
adiabatic limit. A Hartree-Fock decomposition is employed for the Hubbard term.
A range of electronic densities are discussed with special emphasis on the
quarter-filling ($n=0.5$). We argue that the quarter-filled system is relevant
for the electronic properties observed at the interface between LaAlO$_3$ and
SrTiO$_3$, where half-electron per unit cell is transferred to the TiO$_2$
layer as a consequence of the polar discontinuity at the interface. In addition
to presenting the overall phase diagrams, we identify an interesting
charge-ordered antiferromagnetic phase for $n=0.5$, which was also reported
recently in the ab-initio study of the LaAlO$_3$-SrTiO$_3$ interface.


title: Normal State Correlated Electronic Structure of Iron Pnictides

abstract:
  We describe the correlated electronic structure of a prototype Fe-pnictide
superconductor, $SmO_{1-x}F_{x}FeAs$, using LDA+DMFT. Strong, multi-orbital
electronic correlations generate a low-energy pseudogap in the undistorted
phase, giving a bad, incoherent metal in qualitative agreement with
observations. Very good semi-quantitative agreement with the experimental
spectral functions is seen, and interpreted, within a correlated, multi-orbital
picture. Our results show that Fe-pnictides should be understood as low-carrier
density, incoherent metals, in resemblance to the underdoped cuprate
superconductors.


title:
Optimal state for keeping reference frames aligned and the Platonic
  solids

abstract:
  The optimal N qubit states featuring highest sensitivity to small
misalignment of cartesian reference frames are found using the Quantum
Cramer-Rao bound. It is shown that the optimal states are supported on the
symmetric subspace and hence are mathematically equivalent to a single spin
J=N/2. Majorana representation of spin states is used to reveal a beautiful
connection between the states optimal for aligning reference frames and the
platonic solids.


title: Sequential detection of Markov targets with trajectory estimation

abstract:
  The problem of detection and possible estimation of a signal generated by a
dynamic system when a variable number of noisy measurements can be taken is
here considered. Assuming a Markov evolution of the system (in particular, the
pair signal-observation forms a hidden Markov model), a sequential procedure is
proposed, wherein the detection part is a sequential probability ratio test
(SPRT) and the estimation part relies upon a maximum-a-posteriori (MAP)
criterion, gated by the detection stage (the parameter to be estimated is the
trajectory of the state evolution of the system itself). A thorough analysis of
the asymptotic behaviour of the test in this new scenario is given, and
sufficient conditions for its asymptotic optimality are stated, i.e. for almost
sure minimization of the stopping time and for (first-order) minimization of
any moment of its distribution. An application to radar surveillance problems
is also examined.


title:
Fossilization in Geopark Araripe studied through X-ray diffraction,
  scanning microscopy and thermogravimetric analysis

abstract:
  The Geopark Araripe, located in Northeastern Brazil, is the first UNESCO
Natural Park in the South hemisphere and a world-famous fossil deposit of the
Early Cretaceous period (approximately 120 million years). Fossilized fish
fauna in Geopark Araripe is found inside of sedimentary rocks in
three-dimensional forms. In the present study sedimentary rocks and fossil fish
Rhacolepis bucalis have been carefully analysed by means of X-ray powder
diffraction, scanning electron microscopy and termogravimetric analysis.
Mineralogical composition of the fossil fish was explained in terms of facts
occurred at the initial stages of the opening of the South Atlantic and the
oceanic hydrothermal phenomena (``black smoker'', ``white smoker'' and
warm-water events). The occurrence of organic substance was, for the first
time, evaluated in collapsed internal elements (intestinal and muscles) by
termogravimetric analysis.


title: A sign error in the Minkowski space-time plot and its consequences

abstract:
  A sign error in an angle while drawing the original Minkowski plot has
persisted for a century in text books and the pedagogical literature. When it
is corrected, the `length contraction' effect derived from the geometry of the
plot disappears. It is also shown how the `relativity of simultaneity' effect
that has been derived from the plot results from a lack of correspondence
between certain geometrical projections on the plot and the properties of the
physical system --two spatially separated and synchronised clocks in a common
inertial frame-- that they are purported to describe.


title:
Three-body hadronic structure of low-lying $1/2^+$ $\Sigma$ and
  $\Lambda$ resonances

abstract:
  We discuss the dynamical generation of some low-lying $1/2^+$ $\Sigma$'s and
$\Lambda$'s in two-meson one-baryon systems. These systems have been
constructed by adding a pion in $S$-wave to the $\bar{K} N$ pair and its
coupled channels, where the $1/2^-$ $\Lambda$(1405)-resonance gets dynamically
generated. We solve Faddeev equations in the coupled-channel approach to
calculate the $T$-matrix for these systems as a function of the total energy
and the invariant mass of one of the meson-baryon pairs. This squared
$T$-matrix shows peaks at the energies very close to the masses of the
strangeness -1, $1/2^+$ resonances listed in the particle data book.


title: From Dark Energy and Dark Matter to Dark Metric

abstract:
  It is nowadays clear that General Relativity cannot be the definitive theory
of Gravitation due to several shortcomings that come out both from theoretical
and experimental viewpoints. At large scales (astrophysical and cosmological)
the attempts to match it with the latest observational data lead to invoke Dark
Energy and Dark Matter as the bulk components of the cosmic fluid. Since no
final evidence, at fundamental level, exists for such ingredients, it is clear
that General Relativity presents shortcomings at infrared scales. On the other
hand, the attempts to formulate more general theories than Einstein's one give
rise to mathematical difficulties that need workarounds that, in turn, generate
problems from the interpretative viewpoint. We present here a completely new
approach to the mathematical objects in terms of which a theory of Gravitation
may be written in a first-order (a' la Palatini) formalism, and introduce the
concept of Dark Metric which could completely bypass the introduction of
disturbing concepts as Dark Energy and Dark Matter.


title: Overlay Cognitive Radio in Wireless Mesh Networks

abstract:
  In this paper we apply the concept of overlay cognitive radio to the
communication between nodes in a wireless mesh network. Based on the overlay
cognitive radio model, it is possible to have two concurrent transmissions in a
given interference region, where usually only one communication takes place at
a given time. We analyze the cases of wireless mesh networks with regular and
random topologies. Numerical results show that considerable network capacity
gains can be achieved.


title: Solar Models with Revised Abundances and Opacities

abstract:
  Using reconstructed opacities, we construct solar models with low
heavy-element abundance. Rotational mixing and enhanced diffusion of helium and
heavy elements are used to reconcile the recently observed abundances with
helioseismology. The sound speed and density of models where the relative and
absolute diffusion coefficients for helium and heavy elements have been
increased agree with seismically inferred values at better than the 0.005 and
0.02 fractional level respectively. However, the surface helium abundance of
the enhanced diffusion model is too low. The low helium problem in the enhanced
diffusion model can be solved to a great extent by rotational mixing. The
surface helium and the convection zone depth of rotating model M04R3, which has
a surface Z of 0.0154, agree with the seismic results at the levels of 1
$\sigma$ and 3 $\sigma$ respectively. M04R3 is almost as good as the standard
model M98. Some discrepancies between the models constructed in accord with the
new element abundances and seismic constraints can be solved individually, but
it seems difficult to resolve them as a whole scenario.


title: Measuring dark energy with the integrated Sachs-Wolfe effect

abstract:
  I present to this conference our latest measurements of the integrated
Sachs-Wolfe (ISW) effect. After a brief review of the reasons for which this
effect arises and of the technique to detect it by cross-correlating the cosmic
microwave background (CMB) with the large scale structure of the Universe
(LSS), I describe the current state of the art measurement. This is obtained
from a combined analysis of six different galaxy datasets, and has a
significance level of ~ 4.5 sigma. I then describe the cosmological
implications, which show agreement with a flat LCDM model with Omega_m = 0.20
+0.19 -0.11 at 95% confidence level. I finally show how these data can be used
to constrain modified gravity theories, focusing in particular on the
Dvali-Gabadaze-Porrati (DGP) model.


title:
Comparison of different methods for analyzing $\mu$SR line shapes in the
  vortex state of type-II superconductors

abstract:
  A detailed analysis of muon-spin rotation ($\mu$SR) spectra in the vortex
state of type-II superconductors using different theoretical models is
presented. Analytical approximations of the London and Ginzburg-Landau (GL)
models, as well as an exact solution of the GL model were used. The limits of
the validity of these models and the reliability to extract parameters such as
the magnetic penetration depth $\lambda$ and the coherence length $\xi$ from
the experimental $\mu$SR spectra were investigated. The analysis of the
simulated $\mu$SR spectra showed that at high magnetic fields there is a strong
correlation between obtained $\lambda$ and $\xi$ for any value of the
Ginzburg-Landau parameter $\kappa = \lambda/\xi$. The smaller the applied
magnetic field is, the smaller is the possibility to find the correct value of
$\xi$. A simultaneous determination of $\lambda$ and $\xi$ without any
restrictions is very problematic, independent of the model used to describe the
vortex state. It was found that for extreme type-II superconductors and low
magnetic fields, the fitted value of $\lambda$ is practically independent of
$\xi$. The second-moment method frequently used to analyze $\mu$SR spectra by
means of a multi-component Gaussian fit, generally yields reliable values of
$\lambda$ in the whole range of applied fields $ H_{c1} \ll H \lesssim H_{c2}$
($H_{c1}$ and $H_{c2}$ are the first and second critical fields, respectively).
These results are also relevant for the interpretation of small-angle neutron
scattering (SANS) experiments of the vortex state in type-II superconductors.


title:
Angular momentum transport and element mixing in the stellar interior I.
  Application to the rotating Sun

abstract:
  The purpose of this work was to obtain diffusion coefficient for the magnetic
angular momentum transport and material transport in a rotating solar model. We
assumed that the transport of both angular momentum and chemical elements
caused by magnetic fields could be treated as a diffusion process. The
diffusion coefficient depends on the stellar radius, angular velocity, and the
configuration of magnetic fields. By using of this coefficient, it is found
that our model becomes more consistent with the helioseismic results of total
angular momentum, angular momentum density, and the rotation rate in a
radiative region than the one without magnetic fields. Not only can the
magnetic fields redistribute angular momentum efficiently, but they can also
strengthen the coupling between the radiative and convective zones. As a
result, the sharp gradient of the rotation rate is reduced at the bottom of the
convective zone. The thickness of the layer of sharp radial change in the
rotation rate is about 0.036 $R_{\odot}$ in our model. Furthermore, the
difference of the sound-speed square between the seismic Sun and the model is
improved by mixing the material that is associated with angular momentum
transport.


title:
Interferometric 12CO(J=2-1) image of the Nuclear Region of Seyfert 1
  Galaxy NGC 1097

abstract:
  We have mapped the central region of the Seyfert 1 galaxy NGC 1097 in
12CO(J=2-1) with the Submillieter Array (SMA). The 12CO(J=2-1) map shows a
central concentration and a surrounding ring, which coincide respectively with
the Seyfert nucleus and a starburst ring. The line intensity peaks at the
nucleus, whereas in a previously published 12CO(J=1-0) map the intensity peaks
at the starburst ring. The molecular ring has an azimuthally averaged
12CO(J=2-1)/(J=1-0) intensity ratio (R21) of about unity, which is similar to
those in nearby active star forming galaxies, suggesting that most of the
molecular mass in the ring is involved in fueling the starburst. The molecular
gas can last for only about 1.2\times10^8 years without further replenishment
assuming a constant star formation rate and a perfect conversion of gas to
stars. The velocity map shows that the central molecular gas is rotating with
the molecular ring in the same direction, while its velocity gradient is much
steeper than that of the ring. This velocity gradient of the central gas is
similar to what is usually observed in some Seyfert 2 galaxies. To view the
active nucleus directly in the optical, the central molecular gas structure can
either be a low-inclined disk or torus but not too low to be less massive than
the mass of the host galaxy itself, be a highly-inclined thin disk or clumpy
and thick torus, or be an inner part of the galactic disk. The R21 value of
~1.9 of the central molecular gas component, which is significantly higher than
the value found at the molecular gas ring, indicates that the activity of the
Seyfert nucleus may have a significant influence on the conditions of the
molecular gas in the central component.


title:
Photon-Axion-Like Particle Coupling Constant and Cosmological
  Observations

abstract:
  We estimated the photon-pseudoscalar particle mixing constant from the effect
of cosmological alignment and cosmological rotation of polarization plane of
distant QSOs. This effect is explained in terms of birefringent phenomenon due
to photon-pseudoscalar (axion-like) particle mixing in a cosmic magnetic field.
On the contrary, one can estimate the strength of the cosmic magnetic field
using the constraints on the photon-axion-like particle coupling constant from
the CAST experiment and from SNe Ia dimming effect. In a result, the lower
limit on the intergalactic ($z\approx 1\div 2$) magnetic field appears at the
level of about $4\times 10^{-10}\div 10^{-11}$ G.


title:
Monitoring the Large Proper Motions of Radio Sources in the Orion BN/KL
  Region

abstract:
  We present absolute astrometry of four radio sources in the
Becklin-Neugebauer/Kleinman-Low (BN/KL) region, derived from archival data
(taken in 1991, 1995, and 2000) as well as from new observations (taken in
2006). All data consist of 3.6 cm continuum emission and were taken with the
Very Large Array in its highest angular resolution A configuration. We confirm
the large proper motions of the BN object, the radio source I (GMR I) and the
radio counterpart of the infrared source n (Orion-n), with values from 15 to 26
km/s. The three sources are receding from a point between them from where they
seem to have been ejected about 500 years ago, probably via the disintegration
of a multiple stellar system. We present simulations of very compact stellar
groups that provide a plausible dynamical scenario for the observations. The
radio source Orion-n appeared as a double in the first three epochs, but as
single in 2006. We discuss this morphological change. The fourth source in the
region, GMR D, shows no statistically significant proper motions. We also
present new, accurate relative astrometry between BN and radio source I that
restrict possible dynamical scenarios for the region. During the 2006
observations, the radio source GMR A, located about 1' to the NW of the BN/KL
region, exhibited an increase in its flux density of a factor of ~3.5 over a
timescale of one hour. This rapid variability at cm wavelengths is similar to
that previously found during a flare at millimeter wavelengths that took place
in 2003.


title:
Defect kinetics and dynamics of pattern coarsening in a two-dimensional
  smectic-A system

abstract:
  Two-dimensional simulations of the coarsening process of the
isotropic/smectic-A phase transition are presented using a high-order Landau-de
Gennes type free energy model. Defect annihilation laws for smectic
disclinations, elementary dislocations, and total dislocation content are
determined. The computed evolution of the orientational correlation length and
disclination density is found to be in agreement with previous experimental
observations showing that disclination interactions dominate the coarsening
process. The mechanism of smectic disclination movement, limited by the
absorption and emission of elementary dislocations, is found to be facilitated
by curvature walls connecting interacting disclinations. At intermediate times
in the coarsening process, split-core dislocation formation and interactions
displaying an effective disclination quadrupole configuration are observed.
This work provides the framework for further understanding of the formation and
dynamics of the diverse set of curvature defects observed in smectic liquid
crystals and other layered material systems.


title:
On "Ergodicity and Central Limit Theorem in Systems with Long-Range
  Interactions" by Figueiredo et al

abstract:
  In the present paper we refute the criticism advanced in a recent preprint by
Figueiredo et al [1] about the possible application of the $q$-generalized
Central Limit Theorem (CLT) to a paradigmatic long-range-interacting many-body
classical Hamiltonian system, the so-called Hamiltonian Mean Field (HMF) model.
We exhibit that, contrary to what is claimed by these authors and in accordance
with our previous results, $q$-Gaussian-like curves are possible and real
attractors for a certain class of initial conditions, namely the one which
produces nontrivial longstanding quasi-stationary states before the arrival,
only for finite size, to the thermal equilibrium.


title: Is X(3872) a molecule?

abstract:
  We show that the literature on pion exchange between charm and bottom mesons
is inconsistent. We derive the formalism explicitly, expose differences between
papers in the literature and clarify the implications. We show that the X(3872)
can be a bound state but that results are very sensitive to a poorly
constrained parameter. We confirm that bound states in the B Bbar sector are
possible. The circumstances whereby exotic combinations can bind with cc or bb
quantum numbers are explored.


title:
Spectral properties of general advection operators and weighted
  translation semigroups

abstract:
  We investigate the spectral properties of a class of weighted shift
semigroups associated to abstract transport equations with a
Lipschitz--continuous vector field with no--reentry boundary conditions. We
illustrate our results with various examples taken from collisionless kinetic
theory.


title:
Renormalization-group analysis for low-energy scattering of charged
  particles

abstract:
  The low-energy scattering of two charged particles is analyzed using a
renormalization group approach based on dimensional regularization with
power-divergence subtraction. A nontrivial solution with a marginally unstable
direction is found, corresponding to a system with a bound state at zero
energy. For purely energy-dependent perturbations around this solution, the
power counting agrees with that from Wilsonian methods. These terms in the
effective potential are in direct correspondence with the the terms in the
Coulomb-distorted effective-range expansion. We also study perturbations that
depend on off-shell momenta as well as energy, and we show that these affect
only the off-shell form of the scattering matrix. These terms are of higher
order that the corresponding energy-dependent ones and so terms in the
potential that depend only on the off-shell momenta do not have definite orders
in power counting.


title:
Dust-driven Winds and Mass Loss of C-rich AGB Stars with subsolar
  Metallicities

abstract:
  We investigate the mass loss of highly evolved, low- and intermediate mass
stars and stellar samples with subsolar metallicity. We give a qualitative as
well as quantitative description which can be applied to LMC/SMC-type stellar
populations. For that purpose we apply the same approach as we did for solar
metallicity stars and calculate hydrodynamical wind models including dust
formation with LMC and SMC abundances under consideration of an adapted model
assumption. In particular, we improved the treatment of the radiative transfer
problem in order to accommodate larger non-local contributions occurring with
smaller opacities. For each wind model we determine an averaged mass-loss rate.
The resulting, approximate mass-loss formulae are then applied to well-tested
and calibrated stellar evolution calculations in order to quantify the stellar
mass loss. The dynamical models for LMC and SMC metallicity result in mass-loss
rates of the same order of magnitude as the solar metallicity models which is
in this basic approach in agreement with observations. The hydrodynamical
properties like e.g. the outflow velocity differ (for fixed C/O abundance
ratio) noticeably, though. While critical luminosities of LMC and solar
metallicity models fairly coincide, the SMC models need higher luminosities to
develop dust-driven winds.


title:
Sym\'etrie des grandes solutions d'\'equations elliptiques semi
  lin\'eaire

abstract:
  We prove that, if $g$ is a continuous asymptotically convex function, any
solution $u$ of $-\Delta u+g(u)=0$ in a ball B which tends to infinity on
$\partial B$ is radially symmetric.


title:
Likelihood for generally coarsened observations from multi-state or
  counting process models

abstract:
  We consider first the mixed discrete-continuous scheme of observation in
multistate models; this is a classical pattern in epidemiology because very
often clinical status is assessed at discrete visit times while times of death
or other events are observed exactly. A heuristic likelihood can be written for
such models, at least for Markov models; however, a formal proof is not easy
and has not been given yet. We present a general class of possibly non-Markov
multistate models which can be represented naturally as multivariate counting
processes. We give a rigorous derivation of the likelihood based on applying
Jacod's formula for the full likelihood and taking conditional expectation for
the observed likelihood. A local description of the likelihood allows us to
extend the result to a more general coarsening observation scheme proposed by
Commenges & G\'egout-Petit. The approach is illustrated by considering models
for dementia, institutionalization and death.


title: Diffusion versus absorption in semilinear parabolic equations

abstract:
  We study the limit, when $k\to\infty$, of the solutions $u=u_{k}$ of (E)
$\prt_{t}u-\Delta u+ h(t)u^q=0$ in $\BBR^N\ti (0,\infty)$,
$u_{k}(.,0)=k\delta_{0}$, with $q>1$, $h(t)>0$. If $h(t)=e^{-\gw(t)/t}$ where
$\gw>0$ satisfies to $\int_{0}^1\sqrt{\gw(t)}t^{-1}dt<\infty$, the limit
function $u_{\infty}$ is a solution of (E) with a single singularity at
$(0,0)$, while if $\gw(t)\equiv 1$, $u_{\infty}$ is the maximal solution of
(E). We examine similar questions for equations such as $\prt_{t}u-\Gd u^m+
h(t)u^q=0$ with $m>1$ and $\prt_{t}u-\Gd u+ h(t)e^{u}=0$.


title:
Capacitary representations of positive solutions of semilinear parabolic
  equations

abstract:
  We give a global bilateral estimate on the maximal solution $\bar u_F$ of $
\prt_tu-\Delta u+u^q=0$ in $\BBR^N\times (0,\infty)$, $q>1$, $N\geq 1$, which
vanishes at $t=0 $ on the complement of a closed subset $F\subset \BBR^N$. This
estimate is expressed by a Wiener test involving the Bessel capacity
$C_{2/q,q'}$. We deduce from this estimate that $\bar {u}_F$ is
$\sigma$-moderate in Dynkin's sense.


title:
Boundary singularities of solutions of N-harmonic equations with
  absorption

abstract:
  We study the boundary behaviour of solutions $u$ of $-\Delta_{N}u+
|u|^{q-1}u=0$ in a bounded smooth domain $\Omega\subset\mathbb R^{N}$ subject
to the boundary condition $u=0$ except at one point, in the range $q>N-1$. We
prove that if $q\geq 2N-1$ such a $u$ is identically zero, while, if
$N-1<q<2N-1$, $u$ inherits a boundary behaviour which either corresponds to a
weak singularity, or to a strong singularity. Such singularities are
effectively constructed.


title:
N=4 Superconformal Chern-Simons Theories with Hyper and Twisted Hyper
  Multiplets

abstract:
  We extend the N=4 superconformal Chern-Simons theories of Gaiotto and Witten
to those with additional twisted hyper-multiplets. The new theories are
generically linear quiver gauge theories with the two types of hyper-multiplets
alternating between gauge groups. Our construction includes the Bagger-Lambert
model of SO(4) gauge group. A family of abelian theories are identified with
those proposed earlier in the context of the M-crystal model for M2-branes
probing (C^2/Z_n)^2 orbifolds. Possible extension with non-abelian BF couplings
and string/M-theory realization are briefly discussed.


title:
Phase diagram, extended domain walls, and soft collective modes in a
  three component fermionic superfluid

abstract:
  We study the phase diagram of a three-component Fermi gas with weak
attractive interactions, which shows three superfluid and one normal phases. At
weak symmetry breaking between the components the existence of domain walls
interpolating between two superfluids introduces a new length scale much larger
than the coherence length of each superfluid. This, in particular, limits the
applicability of the local density approximation in the trapped case, which we
also discuss. In the same regime the system hosts soft collective modes with a
mass much smaller than the energy gaps of individual superfluids. We derive
their dispersion relations at zero and finite temperatures and demonstrate that
their presence leads to a significant enhancement of fluctuations near the
superfluid-normal transitions.


title: The Duality of the Universe

abstract:
  It is proposed that the physical universe is an instance of a mathematical
structure which possesses a dual structure, and that this dual structure is the
collection of all possible knowledge of the physical universe. In turn, the
physical universe is then the dual space of the latter.


title:
Production of 239 Pu from a natural Uranium disk and "hot" rock using a
  neutron howitzer

abstract:
  A neutron howitzer was used to produce 239Np from the targets of natural U
and a hot rock. An intrinsic Germanium detector enabled the observations of the
gamma rays in the decay of 239Np and a determination of its half life of 2.3
days. This shows that 239Pu had been produced in both targets


title:
On the derivation of exact eigenstates of the generalized squeezing
  operator

abstract:
  We construct the states that are invariant under the action of the
generalized squeezing operator $\exp{(z{a^{\dagger k}}-z^*a^k)}$ for arbitrary
positive integer $k$. The states are given explicitly in the number
representation. We find that for a given value of $k$ there are $k$ such
states. We show that the states behave as $n^{-k/4}$ when occupation number
$n\to\infty$. This implies that for any $k\geq3$ the states are normalizable.
For a given $k$, the expectation values of operators of the form $(a^{\dagger}
a)^j$ are finite for positive integer $j < (k/2-1)$ but diverge for integer
$j\geq (k/2-1)$. For $k=3$ we also give an explicit form of these states in the
momentum representation in terms of Bessel functions.


title: Spin polarons and molecules in strongly-interacting atomic Fermi gases

abstract:
  We examine pairing and molecule formation in strongly-interacting Fermi
gases, and we discuss how radio-frequency (RF) spectroscopy can reveal these
features.
  For the balanced case, the emergence of stable molecules in the BEC regime
results in a two-peak structure in the RF spectrum with clearly visible medium
effects on the low-energy part of the molecular wavefunction.
  For the highly-imbalanced case, we show the existence of a well-defined
quasiparticle (a spin polaron) on both sides of the Feshbach resonance, we
evaluate its lifetime, and we illustrate how its energy may be measured by RF
spectroscopy.


title: Defects and Dressed Boundaries in Complex Sine-Gordon Theory

abstract:
  In this paper we constructed integrable defects in complex sine-Gordon
theory. Soliton and particle interactions with the defect are analysed. Defects
are used to dress Dirichlet boundaries to create a wider class of integrable
boundary conditions to ones previously studied. Properties of these new
boundaries including soliton and particle reflections with the boundaries are
presented.


title:
Bright Planetary Nebulae and their Progenitors in Galaxies Without Star
  Formation

abstract:
  We present chemical abundances for planetary nebulae in M32, NGC 185, and NGC
205 based upon spectroscopy obtained at the Canada-France-Hawaii Telescope
using the Multi-Object Spectrograph. From these and similar data compiled from
the literature for other Local Group galaxies, we consider the origin and
evolution of the stellar progenitors of bright planetary nebulae in galaxies
where star formation ceased long ago. The ratio of neon to oxygen abundances in
bright planetary nebulae is either identical to that measured in the
interstellar medium of star-forming dwarf galaxies or at most changed by a few
percent, indicating that neither abundance is significantly altered as a result
of the evolution of their stellar progenitors. Several planetary nebulae appear
to have dredged up oxygen, but these are the exception, not the rule. The
progenitors of bright planetary nebulae typically enhance their original helium
abundances by less than 50%. In contrast, nitrogen enhancements can reach
factors of 100. However, nitrogen often shows little or no enhancement,
suggesting that nitrogen enrichment is a random process. The helium, oxygen,
and neon abundances argue that the typical bright planetary nebulae in all of
the galaxies considered here are the progeny of stars with initial masses of
approximately 1.5 Msun or less, based upon the nucleosynthesis predictions of
current theoretical models. These models, however, are unable to explain the
nitrogen enrichment or its scatter. Similar conclusions hold for the bright
planetary nebulae in galaxies with ongoing star formation. Thus, though
composition varies significantly, there is unity in the sense that the
progenitors of typical bright planetary nebulae appear to have undergone
similar physical processes. (Abridged)


title:
A practical approach to solve coupled systems of nonlinear partial
  differential equations

abstract:
  In this paper we present the tanh method to obtain exact solutions to coupled
MkDV system. This method may be applied to a variety of coupled systems of
nonlinear ordinary and partial differential equations.


title: A more intuitive definition of limit

abstract:
  Limit can be defined by two axioms: 1. Strict inequality between limits
implies, ultimately, strict inequality between functions. 2. For constant
functions limit is trivial.
  How can basic results on convergence be derived from these axioms? In this
paper we propose two answers: a) at the most elementary level- add two more
axioms, b) at somewhat higher level, do it in three steps, and, in our
forthcoming paper "Axiomatic definition of limit", a third answer- c) do it
neater - in an abstract framework, where only order relations are present.


title:
The singularities of the principal component of the Hilbert scheme of
  points

abstract:
  We show that the principal component of the Hilbert scheme of 9 points in C^8
is not Cohen-Macaulay.


title: Morita Theory For Derived Categories: A Bicategorical Perspective

abstract:
  We present a bicategorical perspective on derived Morita theory for rings, DG
algebras, and spectra. This perspective draws a connection between Morita
theory and the bicategorical Yoneda Lemma, yielding a conceptual unification of
Morita theory in derived and bicategorical contexts. This is motivated by study
of Rickard's theorem for derived equivalences of rings and of Morita theory for
ring spectra, which we present in Sections 2 and 4. Along the way, we gain an
understanding of the barriers to Morita theory for DG algebras and give a
conceptual explanation for the counterexample of Dugger and Shipley.


title: Partial Crossed Product of a group G vs Crossed Product of S(G)

abstract:
  In this work we present a new definition to the Partial Crossed Product by
actions of inverse semigroups in a C^*-algebra, without using the covariant
representations as Sieben did in [5]. Also we present an isomorphism between
the partial crossed products by partial actions of a group G and the partial
crossed product by actions of S(G), an inverse semigroup associated to G
introduced by Exel in [2].


title: Allometric metabolic scaling and fetal and placental weight

abstract:
  We tested the hypothesis that the fetal-placental relationship scales
allometrically and identified modifying factors.
  Among women delivering after 34 weeks but prior to 43 weeks gestation, 24,601
participants in the Collaborative Perinatal Project (CPP) had complete data for
placental gross proportion measures, specifically, disk shape, larger and
smaller disk diameters and thickness, and umbilical cord length. The allometric
metabolic equation was solved for alpha and beta by rewriting PW=
alpha(BW)^beta as Log (PW) = Log(alpha) + beta*Log(BW).
  Mean beta was 0.78+ 0.02 (range 0.66, 0.89), 104% of that predicted by a
supply-limited fractal system (0.75). Gestational age, maternal age, maternal
BMI, parity, smoking, socioeconomic status, infant sex, and changes in
placental proportions each had independent and significant effects on alpha.
Conclusions: In the CPP cohort, the placental - birth weight relationship
scales to approximately 3/4 power.


title:
Gradient estimates for $u_t=\Delta F(u)$ on manifolds and some
  Liouville-type theorems

abstract:
  In this paper, we first prove a localized Hamilton-type gradient estimate for
the positive solutions of Porous Media type equations: $$u_t=\Delta F(u),$$
with $F'(u) > 0$, on a complete Riemannian manifold with Ricci curvature
bounded from below. In the second part, we study Fast Diffusion Equation (FDE)
and Porous Media Equation (PME): $$u_t=\Delta (u^p),\qquad p>0,$$ and obtain
localized Hamilton-type gradient estimates for FDE and PME in a larger range of
$p$ than that for Aronson-B\'enilan estimate, Harnack inequalities and Cauchy
problems in the literature. Applying the localized gradient estimates for FDE
and PME, we prove some Liouville-type theorems for positive global solutions of
FDE and PME on noncompact complete manifolds with nonnegative Ricci curvature,
generalizing Yaus celebrated Liouville theorem for positive harmonic functions.


title: Low-energy theory of disordered interacting quantum wires

abstract:
  We derive an effective low-energy theory of disordered interacting quantum
wires. Our theory describes Anderson localization in the limit of vanishing
dephasing and reduces to standard abelian bosonization in the limit of
vanishing disorder. In a system with many transport channels, it exhibits the
diffusive physics characteristic for multi-channel quantum wires.


title: In\'egalit\'es de Poincar\'e cin\'etiques

abstract:
  In this note we prove Poincar\'e type inequalities for a family of kinetic
equations. We apply this inequality to the variational solution of a linear
kinetic model.


title: Nonlinear Schrodinger Equations and N=2 Superconformal Algebra

abstract:
  We obtain new coupled super Nonlinear Schrodinger equations by using AKNS
scheme and soliton connection taking values in N=2 superconformal algebra.


title: Quantum behavior of the dc SQUID phase qubit

abstract:
  We analyze the behavior of a dc Superconducting Quantum Interference Device
(SQUID) phase qubit in which one junction acts as a phase qubit and the rest of
the device provides isolation from dissipation and noise in the bias leads.
Ignoring dissipation, we find the two-dimensional Hamiltonian of the system and
use numerical methods and a cubic approximation to solve Schrodinger's equation
for the eigenstates, energy levels, tunneling rates, and expectation value of
the currents in the junctions. Using these results, we investigate how well
this design provides isolation while preserving the characteristics of a phase
qubit. In addition, we show that the expectation value of current flowing
through the isolation junction depends on the state of the qubit and can be
used for non-destructive read out of the qubit state.


title: Consequence of reputation in an open-ended Naming Game

abstract:
  We study a modified version of the Naming Game, a recently introduced model
which describes how shared vocabulary can emerge spontaneously in a population
without any central control. In particular, we introduce a new mechanism that
allows a continuous interchange with the external inventory of words. A novel
playing strategy, influenced by the hierarchical structure that individuals'
reputation defines in the community, is implemented. We analyze how these
features influence the convergence times, the cognitive efforts of the agents
and the scaling behavior in memory and time.


title: Absence of Triangles in Maximal Supergravity Amplitudes

abstract:
  From general arguments, we show that one-loop n-point amplitudes in
colourless theories satisfy a new type of reduction formula. These lead to the
existence of cancellations beyond supersymmetry. Using such reduction relations
we prove the no-triangle hypothesis in maximal supergravity by showing that in
four dimensions the n-point graviton amplitude contain only scalar box integral
functions. We also discuss the reduction formulas in the context of gravity
amplitudes with less and no supersymmetry.


title: Gravitational Interstellar Scintillation

abstract:
  Gravitation could modulate the interstellar scintillation of pulsars in a way
that is analogous to refractive interstellar scintillation (RISS). While RISS
occurs when a large ionized cloud crosses the pulsar line-of-sight,
gravitational interstellar scintillation (GISS) occurs when a compact
gravitational deflector lies very near to that line-of-sight. However, GISS
differs from RISS in at least two important respects: It has a very distinctive
and highly predictible time signature, and it is non-dispersive. We find two
very different astronomical contexts where GISS could cause observable
diffraction-pattern distortions: Highly inclined binary pulsars, and the kind
of compact interstellar clouds suspected of causing extreme scattering events.


title:
Towards a Measurement of the Inclusive W->ev Cross Section in pp
  Collisions at sqrt(s) = 14 TeV

abstract:
  We present the methods for an early measurement of the inclusive W->ev
production cross section in pp collisions at sqrt(s)= 14 TeV. The methods are
studied assuming 10 inverse picobarn integrated luminosity of the data and
conditions of the Compact Muon Solenoid (CMS) detector at the early data taking
period.


title: Amenability properties of the centres of group algebras

abstract:
  Let G be a locally compact group, and ZL1(G) be the centre of its group
algebra. We show that when $G$ is compact ZL1(G) is not amenable when G is
either nonabelian and connected, or is a product of infinitely many finite
nonabelian groups. We also, study, for some non-compact groups G, some
conditions which imply amenability and hyper-Tauberian property, for ZL1(G).


title:
Combined analysis of solar neutrino and solar irradiance data: further
  evidence for variability of the solar neutrino flux and its implications
  concerning the solar core

abstract:
  A search for any particular feature in any single solar neutrino dataset is
unlikely to establish variability of the solar neutrino flux since the count
rates are very low. It helps to combine datasets, and in this article we
examine data from both the Homestake and GALLEX experiments. These show
evidence of modulation with a frequency of 11.85 yr-1, which could be
indicative of rotational modulation originating in the solar core. We find that
precisely the same frequency is prominent in power spectrum analyses of the
ACRIM irradiance data for both the Homestake and GALLEX time intervals. These
results suggest that the solar core is inhomogeneous and rotates with sidereal
frequency 12.85 yr-1. We find, by Monte Carlo calculations, that the
probability that the neutrino data would by chance match the irradiance data in
this way is only 2 parts in 10,000. This rotation rate is significantly lower
than that of the inner radiative zone (13.97 yr-1) as recently inferred from
analysis of Super-Kamiokande data, suggesting that there may be a second, inner
tachocline separating the core from the radiative zone. This opens up the
possibility that there may be an inner dynamo that could produce a strong
internal magnetic field and a second solar cycle.


title:
Further Study of an Approach to the Unification of Gauge Symmetries in
  Theories with Dynamical Symmetry Breaking

abstract:
  We extend to larger unification groups an earlier study exploring the
possibility of unification of gauge symmetries in theories with dynamical
symmetry breaking. Based on our results, we comment on the outlook for models
that seek to achieve this type of unification.


title: The tropical analogue of polar cones

abstract:
  We study the max-plus or tropical analogue of the notion of polar: the polar
of a cone represents the set of linear inequalities satisfied by its elements.
We establish an analogue of the bipolar theorem, which characterizes all the
inequalities satisfied by the elements of a tropical convex cone. We derive
this characterization from a new separation theorem. We also establish variants
of these results concerning systems of linear equalities.


title:
Eigenvalues and Eigenfunctions of the Scalar Laplace Operator on
  Calabi-Yau Manifolds

abstract:
  A numerical algorithm for explicitly computing the spectrum of the
Laplace-Beltrami operator on Calabi-Yau threefolds is presented. The requisite
Ricci-flat metrics are calculated using a method introduced in previous papers.
To illustrate our algorithm, the eigenvalues and eigenfunctions of the
Laplacian are computed numerically on two different quintic hypersurfaces, some
Z_5 x Z_5 quotients of quintics, and the Calabi-Yau threefold with Z_3 x Z_3
fundamental group of the heterotic standard model. The multiplicities of the
eigenvalues are explained in detail in terms of the irreducible representations
of the finite isometry groups of the threefolds.


title: Detecting the B-mode Polarisation of the CMB with Clover

abstract:
  We describe the objectives, design and predicted performance of Clover, which
is a ground-based experiment to measure the faint ``B-mode'' polarisation
pattern in the cosmic microwave background (CMB). To achieve this goal, clover
will make polarimetric observations of approximately 1000 deg^2 of the sky in
spectral bands centred on 97, 150 and 225 GHz. The observations will be made
with a two-mirror compact range antenna fed by profiled corrugated horns. The
telescope beam sizes for each band are 7.5, 5.5 and 5.5 arcmin, respectively.
The polarisation of the sky will be measured with a rotating half-wave plate
and stationary analyser, which will be an orthomode transducer. The sky
coverage combined with the angular resolution will allow us to measure the
angular power spectra between 20 < l < 1000. Each frequency band will employ
192 single polarisation, photon noise limited TES bolometers cooled to 100 mK.
The background-limited sensitivity of these detector arrays will allow us to
constrain the tensor-to-scalar ratio to 0.026 at 3sigma, assuming any polarised
foreground signals can be subtracted with minimal degradation to the 150 GHz
sensitivity. Systematic errors will be mitigated by modulating the polarisation
of the sky signals with the rotating half-wave plate, fast azimuth scans and
periodic telescope rotations about its boresight. The three spectral bands will
be divided into two separate but nearly identical instruments - one for 97 GHz
and another for 150 and 225 GHz. The two instruments will be sited on identical
three-axis mounts in the Atacama Desert in Chile near Pampa la Bola.
Observations are expected to begin in late 2009.


title: Elucidation of differential response networks from toxicogenomics data

abstract:
  We describe a novel approach to the analysis of toxicogenomics data and
elucidation of biological networks affected by drug treatments. In this method
approximately 15,000 linear pathway modules were generated from manually
assembled pathway maps from MetaCore (GeneGo, Inc.). Microarray expression data
from livers of rat exposed to phenobarbital, mestranol and tamoxifen were
mapped onto these modules. Using different analytical techniques we have
identified sets of "differential" pathways featuring highly correlated
expression among multiple repeats of the same treatment while showing strong
anti-correlation across different treatments. Network modules distinguishing
chemical treatments were re-assembled based on these pathways. Unlike
traditional statistical and clustering procedures in expression profiling, our
method takes into account both network connectivity and gene expression in the
course of the analysis. We demonstrate that it enables identification of
important cellular mechanisms involved in drug response that would have been
missed by the analysis based on individual gene expression profiles.


title:
Recent results in high-energy longitudinal polarized proton-proton
  collisions at 200GeV at RHIC

abstract:
  We report on recent results of the longitudinal double-spin asymmetry A_LL
from the STAR and PHENIX experiments. Data were collected in longitudinally
polarized proton-proton collisions at a center-of-mass energy of 200 GeV. The
results added new constraints to the polarized gluon distribution function g(x)
with the probed x range of 0:02 < x < 0:3. The results lead to the importance
of probing small x.


title: Itinerant Ferromagnetism in an Atom Trap

abstract:
  We propose an experiment to explore the magnetic phase transitions in
interacting fermionic Hubbard systems, and describe how to obtain the
ferromagnetic phase diagram of itinerant electron systems from these
observations. In addition signatures of ferromagnetic correlations in the
observed ground states are found: for large trap radii (trap radius $R_T > 4$,
in units of coherence length $\xi$), ground states are topological in nature --
a "skyrmion" in 2D, and a "hedgehog" in 3D.


title:
Extending the Coinvariant Theorems of Chevalley, Shephard--Todd,
  Mitchell and Springer

abstract:
  We extend in several directions invariant theory results of Chevalley,
Shephard and Todd, Mitchell and Springer. Their results compare the group
algebra for a finite reflection group with its coinvariant algebra, and compare
a group representation with its module of relative coinvariants. Our extensions
apply to arbitrary finite groups in any characteristic.


title:
An Imprint of Super-Structures on the Microwave Background due to the
  Integrated Sachs-Wolfe Effect

abstract:
  We measure hot and cold spots on the microwave background associated with
supercluster and supervoid structures identified in the Sloan Digital Sky
Survey Luminous Red Galaxy catalog. The structures give a compelling visual
imprint, with a mean temperature deviation of 9.6 +/- 2.2 microK, i.e. above 4
sigma. We interpret this as a detection of the late-time Integrated Sachs-Wolfe
(ISW) effect, in which cosmic acceleration from dark energy causes
gravitational potentials to decay, heating or cooling photons passing through
density crests or troughs. In a flat universe, the linear ISW effect is a
direct signal of dark energy.


title: Comments on Orientifolds without Vector Structure

abstract:
  We revisit type I compactifications with a Spin(32)/Z2 gauge bundle that
admits no vector structure. We elucidate the relation of this Z2 obstruction to
discrete B-field flux and to 't Hooft flux and clarify some subtleties in the
T-duality transformation to type IIA intersecting D-brane models. We reexamine
the earliest 3-generation GUT model on magnetized D-branes and show its
consistency when a discrete B-flux is switched on. We further generalize
partially known results for toroidal models to type I compactifications without
vector structure and their mirror dual type IIA orientifolds on genuine
Calabi-Yau manifolds. We illustrate this by working out the example of the
quintic in some detail.


title:
Coulomb-interaction effects in full counting statistics of a quantum-dot
  Aharonov-Bohm interferometer

abstract:
  We study the effect of Coulomb interaction on the full counting statistics of
an Aharonov-Bohm (AB) interferometer with a single-level quantum dot in one arm
in the regime of weak dot-lead and lead-lead tunnel couplings. In the absence
of Coulomb interaction, the interference processes are of nonresonant nature
with an even AB flux dependence and obey bidirectional Poissonian statistics.
For large charging energy, the statistic of these processes changes. In
addition, processes of resonant nature with an odd flux dependence appear. In
the limit of strongly asymmetric tunnel couplings from the dot to the left and
right leads, their statistics is found to be strongly super-Poissonian.


title:
SU(2)-invariant continuum theory for an unconventional phase transition
  in a three-dimensional classical dimer model

abstract:
  We derive a continuum theory for the phase transition in a classical dimer
model on the cubic lattice, observed in recent Monte Carlo simulations. Our
derivation relies on the mapping from a three-dimensional classical problem to
a two-dimensional quantum problem, by which the dimer model is related to a
model of hard-core bosons on the kagome lattice. The dimer-ordering transition
becomes a superfluid-Mott insulator quantum phase transition at fractional
filling, described by an SU(2)-invariant continuum theory.


title: The Toroidal Obscuration of Active Galactic Nuclei

abstract:
  Observations give strong support for the unification scheme of active
galactic nuclei. The scheme is premised on toroidal obscuration of the central
engine by dusty clouds that are individually very optically thick. These
lectures summarize the torus properties, describe the handling and implications
of its clumpy nature and present speculations about its dynamic origin.


title: Kinetic terms in warped compactifications

abstract:
  We develop formalism for computing the kinetic terms of 4d fields in string
compactifications, particularly with warping. With the help of the Hamiltonian
approach, we identify a gauge dependent inner product on the compactification
manifold which depends on the warp factor. It is shown that kinetic terms are
associated to the minimum value of the inner product over each gauge orbit. We
work out the kinetic term for the complex modulus of a deformed conifold with
flux, i.e. the Klebanov-Strassler solution embedded in a compact Calabi-Yau
manifold. Earlier results of a power-like divergence are confirmed
qualitatively (the kinetic term does contain the main effect of warping) but
not quantitatively (the correct results differ by an order one coefficient).


title: One-Loop Riemann Surfaces in Schnabl Gauge

abstract:
  Due to a peculiar behavior at the open string midpoint, loop diagrams in
Schnabl gauge were expected to fail to produce the relevant closed string
moduli. We find that closed string moduli are generated because the Riemann
surfaces are built with slanted wedges: semi-infinite strips whose edges have
parameterizations related by scaling. We examine in detail one-loop string
diagrams and find that the closed string modulus is always produced. Moreover,
the conformal maps simplify so greatly that both closed and open moduli become
simple calculable functions of the Schwinger parameters, a simplification that
occurs neither in Siegel gauge nor in light-cone gauge.


title:
Missing baryons, bulk flows and the E-mode polarization of the Cosmic
  Microwave Background

abstract:
  If the peculiar motion of galaxy groups and clusters indeed resembles that of
the surrounding baryons, then the kinetic Sunyaev-Zel'dovich (kSZ) pattern of
those massive halos should be closely correlated to the kSZ pattern of all
surrounding electrons. Likewise, it should also be correlated to the CMB E-mode
polarization field generated via Thomson scattering after reionization. We
explore the cross-correlation of the kSZ generated in groups and clusters to
the all sky E-mode polarization in the context of upcoming CMB experiments like
Planck, ACT, SPT or APEX. We find that this cross-correlation is effectively
probing redshifts below $z=3-4$ (where most of baryons cannot be seen), and
that it arises in the very large scales ($l<10$). The significance with which
this cross-correlation can be measured depends on the Poissonian uncertainty
associated to the number of halos where the kSZ is measured and on the accuracy
of the kSZ estimations themselves. Assuming that Planck can provide a cosmic
variance limited E-mode polarization map at $l<20$ and S/N $\sim 1$ kSZ
estimates can be gathered for all clusters more massive than $10^{14}
M_{\odot}$, then this cross-correlation should be measured at the 2--3 $\sigma$
level. Further, if an all-sky ACT or SPT type CMB experiment provides similar
kSZ measurements for all halos above $10^{13} M_{\odot}$, then the
cross-correlation total signal to noise (S/N) ratio should be at the level of
4--5. A detection of this cross-correlation would provide direct and definite
evidence of bulk flows and missing baryons simultaneously.


title: Dark energy from gravitoelectromagnetic inflation?

abstract:
  Gravitoectromagnetic Inflation (GI) was introduced to describe in an unified
manner, electromagnetic, gravitatory and inflaton fields from a 5D vacuum
state. On the other hand, the primordial origin and evolution of dark energy is
today unknown. In this letter we show using GI that the zero modes of some
redefined vector fields $B_i=A_i/a$ produced during inflation, could be the
source of dark energy in the universe.


title:
The Period-Luminosity Relation of RR Lyrae Stars in the SDSS Photometric
  System

abstract:
  We provide the first detailed study of the RR Lyrae period-luminosity (PL)
relation in the ugriz bandpasses of the Sloan Digital Sky Survey (SDSS) filter
system. We argue that tight, simple PL relations are not present in the SDSS
filters, except for the redder bandpasses i and (especially) z. However, for
all bandpasses, we show that, by incorporating terms involving a (fairly
reddening-independent) "pseudo-color" C_0 = (u-g)_0 - (g-r)_0, tight
(non-linear) relations do obtain. We provide theoretically calibrated such
relations in the present paper, which should be useful to derive precise
absolute magnitudes (hence distances) and intrinsic colors (hence reddening
values) to even {\em individual} field RR Lyrae stars. For applications to
cases where photometry in all five passbands may not be available, we also
provide simple (though less precise) average PL relations for the i and z
bandpasses, which read as follows:
  M_z = 0.839 - 1.295 log P + 0.211 log Z,
  M_i = 0.908 - 1.035 log P + 0.220 log Z.
  Similarly, simple period-color relations for (r-i)_0, (g-r)_0, and (u-z)_0
are also provided.


title: Field dynamics and tunneling in a flux landscape

abstract:
  We investigate field dynamics and tunneling between metastable minima in a
landscape of Type IIB flux compactifications, utilizing monodromies of the
complex structure moduli space to continuously connect flux vacua. After
describing the generic features of a flux-induced potential for the complex
structure and Type IIB axio-dilaton, we specialize to the Mirror Quintic
Calabi--Yau to obtain an example landscape. Studying the cosmological dynamics
of the complex structure moduli, we find that the potential generically does
not support slow-roll inflation and that in general the landscape separates
neatly into basins of attraction of the various minima. We then discuss
tunneling, with the inclusion of gravitational effects, in many-dimensional
field spaces. A set of constraints on the form of the Euclidean paths through
field space are presented, and then applied to construct approximate instantons
mediating the transition between de Sitter vacua in the flux landscape. We find
that these instantons are generically thick-wall and that the tunneling rate is
suppressed in the large-volume limit. We also consider examples where
supersymmetry is not broken by fluxes, in which case near-BPS thin-wall bubbles
can be constructed. We calculate the bubble wall tension, finding that it
scales like a D- or NS-brane bubble, and comment on the implications of this
correspondence. Finally, we present a brief discussion of eternal inflation in
the flux-landscape.


title:
Comparative analysis of transport communication networks and q-type
  statistics

abstract:
  We have obtained the Tsallis distribution from the maximum entropy approach
using constraints on the first and the second moment, together with the
normalization condition. We have constructed railway and highway communication
networks for the Moscow region and the airline network for the Russian
Federation. The fitting shows that the degree distributions for these networks
are described with the q-exponential function. In case of the railway and
highway networks, the nodes degrees distributions are well fitted with the
skewed normal distribution, while in case of the airline networks we have used
the power law distribution for fitting. The studies of the epidemics spreading
processes in these networks show that the epidemics threshold decreases with a
decrease of the constraint on the degree.


title:
Three-Dimensional MHD Simulation of the 2003 October 28 Coronal Mass
  Ejection: Comparison with LASCO Coronagraph Observations

abstract:
  We numerically model the coronal mass ejection (CME) event of October 28,
2003 that erupted from active region 10486 and propagated to Earth in less than
20 hours causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model
is formulated by first arriving at a steady state corona and solar wind
employing synoptic magnetograms. We initiate two CMEs from the same active
region, one approximately a day earlier that preconditions the solar wind for
the much faster CME on the 28th. This second CME travels through the corona at
a rate of over 2500 km s$^{-1}$ driving a strong forward shock. We clearly
identify this shock in an image produced by the Large Angle Spectrometric
Coronagraph (LASCO) C3, and reproduce the shock and its appearance in synthetic
white light images from the simulation. We find excellent agreement with both
the general morphology and the quantitative brightness of the model CME with
LASCO observations. These results demonstrate that the CME shape is largely
determined by its interaction with the ambient solar wind and may not be
sensitive to the initiation process. We then show how the CME would appear as
observed by wide-angle coronagraphs onboard the Solar Terrestrial Relations
Observatory (STEREO) spacecraft. We find complex time evolution of the
white-light images as a result of the way in which the density structures pass
through the Thomson sphere. The simulation is performed with the Space Weather
Modeling Framework (SWMF).


title: Light Assisted Collisional Loss in a $^{85/87}$Rb Ultracold Optical Trap

abstract:
  We have studied hetero- and homonuclear excited state/ground state collisions
by loading both $^{85}$Rb and $^{87}$Rb into a far off resonant trap (FORT).
Because of the relatively weak confinement of the FORT, we expect the hyperfine
structure of the different isotopes to play a crucial role in the collision
rates. This dependence on hyperfine structure allows us to measure collisions
associated with long range interatomic potentials of different structure: such
as long and short ranged; or such as purely attractive, purely repulsive, or
mixed attractive and repulsive. We observe significantly different loss rates
for different excited state potentials. Additionally, we observe that some
collisional channels' loss rates are saturated at our operating intensities
(~15 mW/cm$^{2}$). These losses are important limitations in loading dual
isotope optical traps.


title: Geometric Control Over the Motion of Magnetic Domain Walls

abstract:
  We propose a method, which enables precise control of magnetic patterns,
relying only on the fundamental properties of the wire and the choice of the
path in the controlled parameter space but not on the rate of motion along this
path. Possible experimental realizations of this mechanism are discussed. In
particular, we show that the domain walls in magnetic nanowires can be
translated by rotation of the magnetic easy axis, or by applying pulses of
magnetic field directed transverse to the magnetic easy axis.

categories: cond-mat.mtrl-sci cond-mat.stat-mech math-ph math.MP


title:
Implementation of a Fourier Matched Filter in CMB Analyses. Application
  to ISW Studies

abstract:
  Aims: Implement a matched filter (MF) cross-correlation algorithm in
multipole space and compare it to the standard Angular Cross Power Spectrum
(ACPS) method. Apply both methods on a Integrated Sachs Wolfe (ISW) - Large
Scale Structure (LSS) cross correlation scenario and study how sky masks
influence the multipole range where signal arises and its comparison to
theoretical predictions.
  Methods: The MF requires the inversion of a multipole covariance matrix that
if $f_{sky} \lt 1$ is generally non-diagonal and singular. We use a SVD
approach that focuses on those modes carrying most of the information. We
compare the MF to the ACPS in ISW-LSS Monte Carlo simulations, paying attention
on the effect that a limited sky coverage has on the cross-correlation results.
  Results: Within the linear data model for which the MF is defined, the MF
performs comparatively better than the ACPS for smaller values of $f_{sky}$ and
scale dependent (non-Poissonian) noise fields. In the context of ISW studies
both methods are comparable, although the MF performs slightly more sensitively
under more restrictive masks. A preliminary study predicts that most of the
ISW--LSS cross correlation S/N ratio should be found in the very large scales
(50% of the S/N at $l\lt 10$, 90% at $l\lt 40-50$), and this is confirmed by
Monte Carlo simulations. The statistical significance of our cross-correlation
statistics reaches its maximum when considering $l\in [2,l_{max}]$, with
$l_{max} \in[5,40]$ for all values of $f_{sky}$ observed, despite of the
smoothing and power aliasing that aggressive masks introduce in Fourier space.
This $l$-confinement of the ISW-LSS cross correlation should enable a safe
distinction from other secondary effects arising at smaller angular scales.


title:
Quantum communication between trapped ions through a dissipative
  environment

abstract:
  We study two trapped ions coupled to the axial phonon modes of a
one-dimensional Coulomb crystal. This system is formally equivalent to the "two
spin-boson" model. We propose a scheme to dynamically generate a maximally
entangled state of two ions within a decoherence-free subspace. Here the
phononic environment of the trapped ions, whatever its temperature and number
of modes, serves as the entangling bus. The efficient production of the pure
singlet state can be exploited to perform short-ranged quantum communication
which is essential in building up a large-scale quantum computer.


title:
Atomic Layer Deposition of Metal Oxides on Pristine and Functionalized
  Graphene

abstract:
  We investigate Atomic Layer Deposition (ALD) of metal oxide on pristine and
functionalized graphene. On pristine graphene, ALD coating can only actively
grow on edges and defect sites, where dangling bonds or surface groups react
with ALD precursors. This affords a simple method to decorate and probe single
defect sites in graphene planes. We used perylene tetracarboxylic acid (PTCA)
to functionalize graphene surface and selectively introduced densely packed
surface groups on graphene. Uniform ultrathin ALD coating on PTCA graphene was
achieved over large area. The functionalization method could be used to
integrate ultrathin high-k dielectrics in future graphene electronics.


title: Local stress and superfluid properties of solid Helium-4

abstract:
  More than half a century ago Penrose asked: are the superfluid and solid
state of matter mutually exclusive or do there exist "supersolid" materials
where the atoms form a regular lattice and simultaneously flow without
friction? Recent experiments provide evidence that supersolid behavior indeed
exists in Helium-4 -- the most quantum material known in Nature. In this paper
we show that large local strain in the vicinity of crystalline defects is the
origin of supersolidity in Helium-4. Although ideal crystals of Helium-4 are
not supersolid, the gap for vacancy creation closes when applying a moderate
stress. While a homogeneous system simply becomes unstable at this point, the
stressed core of crystalline defects (dislocations and grain boundaries)
undergoes a radical transformation and can become superfluid.


title:
Electric-magnetic asymmetry of the A^2 condensate and the phases of
  Yang-Mills theory

abstract:
  We study the finite-temperature behavior of the A^2 condensate in the Landau
gauge of SU(2) Yang--Mills theory on the lattice in a wide range of
temperatures. The asymmetry between the electric (temporal) and magnetic
(spatial) components of this unconventional dimension-2 condensate is a
convenient ultraviolet-finite quantity which possesses, as we demonstrate,
unexpected properties. The low-temperature behavior of the condensate asymmetry
suggests that the mass of the lowest thermal excitation in the condensate is
unexpectedly low, about 200 MeV, which is much smaller than the glueball mass.
The asymmetry is peaking at the phase transition, becoming a monotonically
decreasing function in the deconfinement phase. A symmetric point is reached in
the deconfinement phase at a temperature approximately equal twice the critical
temperature. The behavior of the electric-magnetic asymmetry of the condensate
separates the phase diagram of Yang-Mills theory into three regions. We suggest
that these regions are associated with the condensed, liquid and gaseous states
of the confining gluonic objects, the Abelian monopoles.


title: A boundary value problem for minimal Lagrangian graphs

abstract:
  Let \Omega and \tilde{\Omega} be uniformly convex domains in \mathbb{R}^n
with smooth boundary. We show that there exists a diffeomorphism f: \Omega \to
\tilde{\Omega} such that the graph \Sigma = \{(x,f(x)): x \in \Omega\} is a
minimal Lagrangian submanifold of \mathbb{R}^n \times \mathbb{R}^n.


title: Tunneling into fuzzball states

abstract:
  String theory suggests that black hole microstates are quantum, horizon sized
`fuzzballs', rather than smooth geometries with horizon. Radiation from
fuzzballs can carry information and does not lead to information loss. But if
we let a shell of matter collapse then it creates a horizon, and it seems that
subsequent radiation will lead to information loss. We argue that the
resolution to this problem is that the shell can tunnel to the fuzzball
configurations. The amplitude for tunneling is small because we are relating
two macroscopically different configurations, but the number of states that we
can tunnel to, given through the Bekenstein entropy, is very large. These small
and large numbers can cancel each other, making it possible for the shell to
tunnel into fuzzball states before a significant amount of radiation has been
emitted. This offers a way to resolve the information paradox.


title:
Quantum Criticality out of Equilibrium: Steady State in a Magnetic
  Single-Electron Transistor

abstract:
  Quantum critical systems out of equilibrium are of extensive interest, but
are difficult to study theoretically. We consider here the steady state limit
of a single electron transistor, which is attached to ferromagnetic leads and
subjected to a finite bias voltage (V). In equilibrium (i.e., V=0), this system
undergoes a continuous quantum phase transition with a critical destruction of
the Kondo effect. We construct an exact quantum Boltzmann treatment in a
dynamical large-N limit, and determine the universal scaling functions for the
I-V characteristics covering both the linear and non-linear regimes. We also
elucidate the scaling properties of both the fluctuation-dissipation ratios and
the decoherence properties as encoded in the local spin response.


title:
Anomalous Conductance Oscillations and Half-Metallicity in Atomic Ag-O
  Chains

abstract:
  Using spin density functional theory we study the electronic and magnetic
properties of atomically thin, suspended chains containing silver and oxygen
atoms in an alternating sequence. Chains longer than 4 atoms develop a
half-metallic ground state implying fully spin polarized charge carriers. The
conductances of the chains exhibit weak even-odd oscillations around an
anomalously low value of 0.1G_0 (G_0 = 2e^2h) which coincide with the averaged
experimental conductance in the long chain limit. The unusual conductance
properties are explained in terms of a resonating-chain model which takes the
reflection probability and phase-shift of a single bulk-chain interface as the
only input. The model also explains the conductance oscillations for other
metallic chains.


title:
Thermal Behaviour of $\pi-\pi$ Scattering Lengths in the
  Nambu--Jona-Lasinio model

abstract:
  We calculate the thermal evolution of $\pi-\pi$ scattering lengths, in the
frame of the Nambu--Jona-Lasinio model. The thermal corrections were calculated
at the one loop level using Thermofield Dynamics. We present also results for
the pion thermal mass. Our procedure implies the modeling of a propagating
scalar meson as a resumation of chains of quark bubbles, which is presented
explicitly. We compare our results with previous analysis of this problem in
the frame of different theoretical approaches.


title: Trilepton production at the CERN LHC: Standard model sources and beyond

abstract:
  Events with three or more isolated leptons in the final state are known to be
signatures of new physics phenomena at high energy collider physics facilities.
Standard model sources of isolated trilepton final states include gauge boson
pair production such as $WZ$ and $W\gamma^*$, and $t\bar{t}$ production. We
demonstrate that leptons from heavy flavor decays, such as $b \to lX$ and $c
\to lX$, provide sources of trileptons that can be orders-of-magnitude larger
after cuts than other standard model backgrounds to new physics processes. We
explain the physical reason heavy flavor backgrounds survive isolation cuts. We
propose new cuts to control the backgrounds in the specific case of chargino
plus neutralino pair production in supersymmetric models. After these cuts are
imposed, we show that it should be possible to find at least a 4 sigma excess
for supersymmetry parameter space point LM9 with 30 fb$^{-1}$ of integrated
luminosity.


title: Elliptic Flow of Rare High-Momentum Probes in Nuclear Collisions

abstract:
  In high energy nuclear collisions the leading parton of a jet can change
flavor through interactions with the surrounding medium. This can considerably
boost the relative yield of rare high momentum particles, like strange quarks
and photons. We revisit these jet conversions and discuss implications for the
azimuthal asymmetry $v_2$ of rare probes. We predict that the $v_2$ of kaons at
RHIC falls significantly below that of pions and protons at high transverse
momentum. Experimental information on the relative $v_2$ of strange hadrons
could provide constraints on the mean free path of fast quarks and gluons in a
quark gluon plasma.


title:
New Low-Mass Stars and Brown Dwarfs with Disks in the Chamaeleon I
  Star-Forming Region

abstract:
  We have used images obtained with the Infrared Array Camera and the Multiband
Imaging Photometer onboard the Spitzer Space Telescope to search for low-mass
stars and brown dwarfs with circumstellar disks in the Chamaeleon I
star-forming region. Through optical spectroscopy of sources with red colors in
these data, we have identified seven new disk-bearing members of the cluster.
Three of these objects are probably brown dwarfs according to their spectral
types (M8, M8.5, M8-L0). Three of the other new members may have edge-on disks
based on the shapes of their infrared spectral energy distributions. One of the
possible edge-on systems has a steeply rising slope from 4.5 to 24um,
indicating that it could be a class I source (star+disk+envelope) rather than a
class II source (star+disk). If so, then it would be one of the least massive
known class I protostars (M5.75, M~0.1 Msun).


title: Dispersive optomechanics: a membrane inside a cavity

abstract:
  We present the results of theoretical and experimental studies of
dispersively coupled (or "membrane in the middle") optomechanical systems. We
calculate the linear optical properties of a high finesse cavity containing a
thin dielectric membrane. We focus on the cavity's transmission, reflection,
and finesse as a function of the membrane's position along the cavity axis and
as a function of its optical loss. We compare these calculations with
measurements and find excellent agreement in cavities with empty-cavity
finesses in the range 10^4 to 10^5. The imaginary part of the membrane's index
of refraction is found to be approximately 10^(-4). We calculate the laser
cooling performance of this system, with a particular focus on the
less-intuitive regime in which photons "tunnel" through the membrane on a time
scale comparable to the membrane's period of oscillation. Lastly, we present
calculations of quantum non-demolition measurements of the membrane's phonon
number in the low signal-to-noise regime where the phonon lifetime is
comparable to the QND readout time.


title: Comment on "Theory of Spin Hall Effect: Extension of the Drude Model"

abstract:
  E. M. Chudnovsky has recently posted on the ArXive his Reply
(arXiv:0805.2918) to my Comment (Phys. Rev. Lett. 100, 199703 (2008)) on his
recent Letter (E. M. Chudnovsky, Phys. Rev. Lett. 99, 206601 (2007)). In order
to avoid possible misunderstandings in the evaluation of his Letter, I am
posting my Comment with some remarks on the contents of his Reply.


title: Fluctuation-driven capacity distribution in complex networks

abstract:
  Maximizing robustness and minimizing cost are common objectives in the design
of infrastructure networks. However, most infrastructure networks evolve and
operate in a highly decentralized fashion, which may significantly impact the
allocation of resources across the system. Here, we investigate this question
by focusing on the relation between capacity and load in different types of
real-world communication and transportation networks. We find strong empirical
evidence that the actual capacity of the network elements tends to be similar
to the maximum available capacity, if the cost is not strongly constraining. As
more weight is given to the cost, however, the capacity approaches the load
nonlinearly. In particular, all systems analyzed show larger unoccupied
portions of the capacities on network elements subjected to smaller loads,
which is in sharp contrast with the assumptions involved in (linear) models
proposed in previous theoretical studies. We describe the observed behavior of
the capacity-load relation as a function of the relative importance of the cost
by using a model that optimizes capacities to cope with network traffic
fluctuations. These results suggest that infrastructure systems have evolved
under pressure to minimize local failures, but not necessarily global failures
that can be caused by the spread of local damage through cascading processes.


title: Supersymmetry and Superstring Phenomenology

abstract:
  We briefly cover the early history of supersymmetry, describe the relation of
SUSY quantum field theories to superstring theories and explain why they are
considered a likely tool to describe the phenomenology of high energy particle
theory beyond the Standard Model.


title: About Imperfect Mushroom Billiards

abstract:
  Imperfections of Bunimovich mushroom Billiards are analyzed. Any experiment
will be affected by such imperfections, and it will be necessary to estimate
their influence. In particular some of the corners will be rounded and small
deviations of the angle of the underside of the mushroom head will be
considered. The analysis displayed some unexpected non-generic features. The
latter leads to a transition from a perfect mushroom behavior to either an
ordinary KAM scenario or an abrupt transition to complete chaos, depending on
the sign of the perturbation. The former produces a fractal area of islands and
chaos, in fact a KAM scenario, not associated to the large island of stability
of the mushroom billiard.


title: Counting Gauge Invariant Operators in SQCD with Classical Gauge Groups

abstract:
  We use the plethystic programme and the Molien-Weyl fomula to compute
generating functions, or Hilbert Series, which count gauge invariant operators
in SQCD with the SO and Sp gauge groups. The character expansion technique
indicates how the global symmetries are encoded in the generating functions. We
obtain the full character expansion for each theory with arbitrary numbers of
colours and flavours. We study the orientifold action on SQCD with the SU gauge
group and examine how it gives rise to SQCD with the SO and Sp gauge groups. We
establish that the classical moduli space of SQCD is not only irreducible, but
is also an affine Calabi-Yau cone over a weighted projective variety.


title: Early Universe Cosmology in Internal Relativity

abstract:
  We present a new approach to early universe cosmology. Inflation is replaced
by a phase transition in which both matter and geometry are created
simultaneously. We calculate the spectrum of metric perturbations and show that
it is flat. We then argue that as a consequence of the dynamic nature of the
phase transition the spectrum is likely not completely flat but tilted. We
argue that the tilt is related to $\eta$, one of the critical exponents
characterizing the phase transition. This exponent generically lies between
0.03 and 0.06. It thus coincides with the observed tilt of the perturbation
spectrum. Because the critical exponent is related to the presence of an
additional small length scale we argue that the deviation of the observed
spectrum from flatness might be an experimental indication that our world is in
fact discrete.


title: Nonlinear Dynamic Phenomena in Macroscopic Tunneling

abstract:
  Numerical simulations of the NLSE (or GPE) are presented demonstrating
emission of short pulses of the matter (light) density formed in the course of
tunneling in wave-guided light and/or trapped BEC. The phenomenon is observed
under various conditions, for nonlinearities of different signs, zero
nonlinearity included. We study, both numerically and analytically, pulsations
of matter (light) remaining within the trap and use the results in order to
induce emission of sequential pulses by properly narrowing the trap. This
allows us to propose a mechanism for a realization of Atom Pulse Laser.