title: A lower bound on the mass of Dark Matter particles

abstract:
  We discuss the bounds on the mass of Dark Matter (DM) particles, coming from
the analysis of DM phase-space distribution in dwarf spheroidal galaxies
(dSphs). After reviewing the existing approaches, we choose two methods to
derive such a bound. The first one depends on the information about the current
phase space distribution of DM particles only, while the second one uses both
the initial and final distributions. We discuss the recent data on dSphs as
well as astronomical uncertainties in relevant parameters. As an application,
we present lower bounds on the mass of DM particles, coming from various dSphs,
using both methods. The model-independent bound holds for any type of fermionic
DM. Stronger, model-dependent bounds are quoted for several DM models (thermal
relics, non-resonantly and resonantly produced sterile neutrinos, etc.). The
latter bounds rely on the assumption that baryonic feedback cannot
significantly increase the maximum of a distribution function of DM particles.
For the scenario in which all the DM is made of sterile neutrinos produced via
non-resonant mixing with the active neutrinos (NRP) this gives m_nrp > 1.7 keV.
Combining these results in their most conservative form with the X-ray bounds
of DM decay lines, we conclude that the NRP scenario remains allowed in a very
narrow parameter window only. This conclusion is independent of the results of
the Lyman-alpha analysis. The DM model in which sterile neutrinos are
resonantly produced in the presence of lepton asymmetry remains viable. Within
the minimal neutrino extension of the Standard Model (the nuMSM), both mass and
the mixing angle of the DM sterile neutrino are bounded from above and below,
which suggests the possibility for its experimental search.


title: Fermions and noncommutative theories

abstract:
  By using a framework where the object of noncommutativity $\theta^{\mu\nu}$
represents independent degrees of freedom, we study the symmetry properties of
an extended $x+\theta$ space-time, given by the group $P$', which has the
Poincar\'{e} group $P$ as a subgroup. In this process we use the minimal
canonical extension of the Doplicher, Fredenhagen and Roberts algebra. It is
also proposed a generalized Dirac equation, where the fermionic field depends
not only on the ordinary coordinates but on $\theta^{\mu\nu}$ as well. The
dynamical symmetry content of such fermionic theory is discussed, and we show
that its action is invariant under $\cal P$'.


title:
Exploring the Nuclear Environment of the NLS1 Galaxy Arakelian 564 with
  XMM-Newton RGS

abstract:
  We present an accurate characterisation of the high-resolution X-ray spectrum
of the Narrow Line Seyfert 1 galaxy Arakelian 564 and put it in to context with
other objects of its type by making a detailed comparison of their spectra. The
best fit to the data identifies five significant emission lines at 18.9, 22.1,
24.7, 29.0 and 33.5A due O VIII Ly alpha, O VII(f), N VII Ly alpha, N VI(i) and
C VI Ly alpha respectively. These have an RMS velocity of ~1100km/s and a flow
velocity of ~-600km/s, except for the O VII(f) emission line, which has a flow
velocity consistent with zero. Two separate emitting regions are identified.
Three separate phases of photoionized, X-ray absorbing gas are included in the
fit with ionization parameters log xi=-0.86, 0.87, 2.56 and column densities
N_H=0.89, 2.41, 6.03*10^20cm^-2 respectively. All three phases show this to be
an unusually low velocity outflow (-10pm100km/s) for a narrow line Seyfert 1.
We present the hypothesis that the BLR is the source of the NLR and warm
absorber, and examine optical and UV images from the XMM-Newton Optical Monitor
to relate our findings to the characteristics of the host galaxy.


title: Rebound Shock Breakouts of Exploding Massive Stars: A MHD Void Model

abstract:
  With a self-similar magnetohydrodynamic (MHD) model of an exploding
progenitor star and an outgoing rebound shock and with the thermal
bremsstrahlung as the major radiation mechanism in X-ray bands, we reproduce
the early X-ray light curve observed for the recent event of XRO 080109/SN
2008D association. The X-ray light curve consists of a fast rise, as the shock
travels into the "visible layer" in the stellar envelope, and a subsequent
power-law decay, as the plasma cools in a self-similar evolution. The observed
spectral softening is naturally expected in our rebound MHD shock scenario. We
propose to attribute the "non-thermal spectrum" observed to be a superposition
of different thermal spectra produced at different layers of the stellar
envelope.


title: Developing of New Facets of Indirect Modeling in the Geosciences

abstract:
  In this paper, we describe some applications of Self Organizing feature map
Neuro-Fuzzy Inference System (SONFIS) and Self Organizing feature map Rough Set
(SORST) in analysis of permeability at a dam site and lost circulation in the
drilling of three wells in Iran. Elicitation of the best rules on the
information tables, exploration of the dominant structures on the behaviour of
systems while they fall in to the balance of the second granulation level
(rules) and highlighting of most effective attributes (parameters) on the
selected systems, are some of the benefits of the proposed methods. In the
other process, using complex networks (graphs) theory - as another method in
not 1:1 modelling branch- mechanical behaviour of a rock joint has been
investigated. Keywords: Information Granules; SONFIS; SORST; Complex Networks;
Permeability; Lost Circulation; Mechanical Behavior of a Rock Joint


title: Gravity, Twistors and the MHV Formalism

abstract:
  We give a self-contained derivation of the MHV amplitudes for gravity and use
the associated twistor generating function to define a twistor action for the
MHV diagram approach to gravity. Starting from a background field calculation
on a spacetime with anti self-dual curvature, we obtain a simple spacetime
formula for the scattering of a single, positive helicity linearized graviton
into one of negative helicity. Re-expressing our integral in terms of twistor
data allows us to consider a spacetime that is asymptotic to a superposition of
plane waves. Expanding these out perturbatively yields the gravitational MHV
amplitudes of Berends, Giele & Kuijf. We go on to take the twistor generating
function off-shell at the perturbative level. Combining this with a twistor
action for the anti self-dual background, we obtain a twistor action for the
MHV diagram approach to perturbative gravity. We finish by extending these
results to supergravity, in particular N=4 and N=8.


title: Gr\"uneisen ratio at the Kondo breakdown quantum critical point

abstract:
  We show that the scenario of multi-scale Kondo breakdown quantum critical
point (QCP) gives rise to a divergent Gr\"uneisen ratio with an anomalous
exponent 0.7. In particular, we fit the experimental data of
$YbRh_{2}(Si_{0.95}Ge_{0.05})_{2}$ for specific heat, thermal expansion, and
Gr\"uneisen ratio based on our simple analytic expressions. A reasonable
agreement between the experiment and theory is found for the temperature range
between 0.4 K and 10 K. We discuss how the Gr\"uneisen ratio is a key
measurement to discriminate between the Kondo breakdown and spin-density wave
theories.


title: Light quark masses from QCD sum rules with minimal hadronic bias

abstract:
  The light quark masses are determined using a new QCD Finite Energy Sum Rule
(FESR) in the pseudoscalar channel. This FESR involves an integration kernel
designed to reduce considerably the contribution of the (unmeasured) hadronic
resonance spectral functions. The QCD sector of the FESR includes perturbative
QCD (PQCD) to five loop order, and the leading non-perturbative terms. In the
hadronic sector the dominant contribution is from the pseudoscalar meson pole.
Using Contour Improved Perturbation Theory (CIPT) the results for the quark
masses at a scale of 2 GeV are $m_u(Q= 2 {GeV}) = 2.9 \pm 0.2 {MeV}$, $m_d(Q= 2
{GeV}) = 5.3 \pm 0.4 {MeV}$, and $m_s(Q= 2 {GeV}) = 102 \pm 8 {MeV}$, for
$\Lambda = 381 \pm 16 {MeV}$, corresponding to $\alpha_s(M_\tau^2) = 0.344
  \pm0.009$. In this framework the systematic uncertainty in the quark masses
from the unmeasured hadronic resonance spectral function amounts to less than 2
- 3 %. The remaining uncertainties above arise from those in $\Lambda$, the
unknown six-loop PQCD contribution, and the gluon condensate, which are all
potentially subject to improvement.


title:
Constraining sterile neutrino dark matter by phase-space density
  observations

abstract:
  We apply phase-space density considerations to obtain lower bounds on the
mass of sterile neutrino as dark matter candidate. The bounds are different for
non-resonant production, resonant production in the presence of lepton
asymmetry and production in decays of heavier particles. In the former case our
bound is comparable to, but independent of the Lyman-alpha bound, and together
with X-ray upper limit it disfavors non-resonantly produced sterile neutrino
dark matter. An interesting feature of the latter case is that warm dark matter
may be composed of heavy particles.


title: Simulability and regularity of complex quantum systems

abstract:
  We show that the transition from regular to chaotic spectral statistics in
interacting many-body quantum systems has an unambiguous signature in the
distribution of Schmidt coefficients dynamically generated from a generic
initial state, and thus limits the efficiency of the t-DMRG algorithm.


title: Excited heavy tetraquarks with hidden charm

abstract:
  The masses of the excited heavy tetraquarks with hidden charm are calculated
within the relativistic diquark-antidiquark picture. The dynamics of the light
quark in a heavy-light diquark is treated completely relativistically. The
diquark structure is taken into account by calculating the diquark-gluon form
factor. New experimental data on charmonium-like states above open charm
threshold are discussed. The obtained results indicate that X(3872), Y(4260),
Y(4360), Z(4248), Z(4433) and Y(4660) could be tetraquark states with hidden
charm.


title: Ultrashort Focused Electromagnetic Pulses

abstract:
  In this article we present a closed analytical description for few-cycle,
focused electromagnetic pulses of arbitrary duration and carrier-envelope-phase
(CEP). Because of the vectorial character of light, not all thinkable
one-dimensional (1D) shapes for the transverse electric field or vector
potential can be realized as finite energy three-dimensional (3D) structures.
We cope with this problem by using a second potential, which is defined as a
primitive to the vector potential. This allows to construct fully consistent 3D
wave-packet solutions for the Maxwell equations, given a solution of the scalar
wave equation. The wave equation is solved for ultrashort, Gaussian and related
pulses in paraxial approximation. The solution is given in a closed and
numerically convenient form, based on the complex error function. All results
undergo thorough numerical testing, validating their correctness and accuracy.
A reliable and accurate representation of few-cycle pulses is e.g. crucial for
analytical and numerical theory of vacuum particle acceleration.


title: Randomization Does Not Justify Logistic Regression

abstract:
  The logit model is often used to analyze experimental data. However,
randomization does not justify the model, so the usual estimators can be
inconsistent. A consistent estimator is proposed. Neyman's non-parametric setup
is used as a benchmark. In this setup, each subject has two potential
responses, one if treated and the other if untreated; only one of the two
responses can be observed. Beside the mathematics, there are simulation
results, a brief review of the literature, and some recommendations for
practice.


title: The modular branching rule for affine Hecke algebras of type A

abstract:
  For the affine Hecke algebra of type A at roots of unity, we make explicit
the correspondence between geometrically constructed simple modules and
combinatorially constructed simple modules and prove the modular branching
rule. The latter generalizes work by Vazirani.


title:
Crash-testing the CAULDRON code for joint lensing and dynamics analysis
  of early-type galaxies

abstract:
  We apply the joint lensing and dynamics code for the analysis of early-type
galaxies, CAULDRON, to a rotating N-body stellar system with dark matter halo
which significantly violates the two major assumptions of the method, i.e.
axial symmetry supported by a two-integral distribution function. The goal is
to study how CAULDRON performs in an extreme case, and to determine which
galaxy properties can still be robustly recovered. Three data sets,
corresponding to orthogonal lines of sight, are generated from the N-body
system and analysed with the identical procedure followed in the study of real
lens galaxies, adopting an axisymmetric power-law total density distribution.
We find that several global properties of the N-body system are recovered with
remarkable accuracy, despite the fact that the adopted power-law model is too
simple to account for the lack of symmetry of the true density distribution. In
particular, the logarithmic slope of the total density distribution is robustly
recovered to within less than 10 per cent (with the exception of the
ill-constrained very inner regions), the inferred angle-averaged radial profile
of the total mass closely follows the true distribution, and the dark matter
fraction of the system (inside the effective radius) is correctly determined
within ~ 10 per cent of the total mass. Unless the line of sight direction is
almost parallel to the total angular momentum vector of the system, reliably
recovered quantities also include the angular momentum, the V/sigma ratio, and
the anisotropy parameter delta. We conclude that the CAULDRON code can be
safely and effectively applied to real early-type lens galaxies, providing
reliable information also for systems that depart significantly from the
method's assumptions.


title: Lithium depletion and the rotational history of exoplanet host stars

abstract:
  Israelian et al. (2004) reported that exoplanet host stars are lithium
depleted compared to solar-type stars without detected massive planets, a
result recently confirmed by Gonzalez (2008). We investigate whether enhanced
lithium depletion in exoplanet host stars may result from their rotational
history. We have developed rotational evolution models for slow and fast
solar-type rotators from the pre-main sequence (PMS) to the age of the Sun and
compare them to the distribution of rotational periods observed for solar-type
stars between 1 Myr and 5 Gyr. We show that slow rotators develop a high degree
of differential rotation between the radiative core and the convective
envelope, while fast rotators evolve with little core-envelope decoupling. We
suggest that strong differential rotation at the base of the convective
envelope is responsible for enhanced lithium depletion in slow rotators. We
conclude that lithium-depleted exoplanet host stars were slow rotators on the
zero-age main sequence (ZAMS) and argue that slow rotation results from a long
lasting star-disk interaction during the PMS. Altogether, this suggests that
long-lived disks (> 5 Myr) may be a necessary condition for massive planet
formation/migration.


title: Population III.1 stars: formation, feedback and evolution of the IMF

abstract:
  I discuss current theoretical expectations of how primordial, Pop III.1 stars
form. Lack of direct observational constraints makes this a challenging task.
In particular predicting the mass of these stars requires solving a series of
problems, which all affect, perhaps drastically, the final outcome. While there
is general agreement on the initial conditions, H_2-cooled gas at the center of
dark matter minihalos, the subsequent evolution is more uncertain. In
particular, I describe the potential effects of dark matter annihilation
heating, fragmentation within the minihalo, magnetic field amplification, and
protostellar ionizing feedback. After these considerations, one expects that
the first stars are massive >~100Msun, with dark matter annihilation heating
having the potential to raise this scale by large factors. Higher accretion
rates in later-forming minihalos may cause the Pop III.1 initial mass function
to evolve to higher masses.


title: Integrable models: from dynamical solutions to string theory

abstract:
  We review the status of integrable models from the point of view of their
dynamics and integrability conditions. Some integrable models are discussed in
detail. We comment on the use it is made of them in string theory. We also
discuss the Bethe Ansatz solution of the SO(6) symmetric Hamiltonian with SO(6)
boundary.
  This work is especially prepared for the seventieth anniversaries of
Andr\'{e} Swieca (in memoriam) and Roland K\"{o}berle.


title: Commissioning of Particle ID at ATLAS and CMS with Early LHC Data

abstract:
  This paper describes latest results on lepton (electron, muon and tau) and
photon particle identification at the ATLAS and CMS experiments, with emphasis
on how the particle identification can be validated and its performance
determined using early LHC data.


title: On the Microscopic Perspective of Black Branes Thermodynamic Geometry

abstract:
  In this article we study correspondence between the microscopic spectrum and
macroscopic properties of a class of extremal and non-extremal black branes and
outline an origin of the interactions among various microstates of a given
black brane configuration from the perspective of an intrinsic Riemannian
geometry arising from the coarse graining entropy over a large number of
microstates. We have analyzed the state-space geometry in the case of various
extremal and non-extremal black branes arising from the string theories,
multi-centered black brane configurations, small black holes with fractional
branes, fuzzy rings in the set up of Mathur's fuzzballs and subensemble theory,
as well as that the black brane foams from the considerations of bubbling black
brane solutions in the M-theory. We have further shown that there exists a
clear mechanism on the black brane side that describes the notion of associated
interactions in the state-space or vice-versa. We thus find that in all such
cases there are no singularities in the state-space manifold of these black
brane configurations. This observation is in turn consistent with the existing
picture of corresponding microscopic CFT data.


title:
Inhomogeneous ferrimagnetic-like behavior in Gd2/3Ca1/3MnO3 single
  crystals

abstract:
  We present a study of the magnetic properties of Gd2/3Ca1/3MnO3 single
crystals at low temperatures. We show that this material behave as an
inhomogeneous ferrimagnet. In addition to small saturation magnetization at 5
K, we have found history dependent effects in the magnetization and the
presence of exchange bias. These features are compatible with microscopic phase
separation in the clean Gd2/3Ca1/3MnO3 system studied.


title:
Gilbert Damping in Conducting Ferromagnets II: Model Tests of the
  Torque-Correlation Formula

abstract:
  We report on a study of Gilbert damping due to particle-hole pair excitations
in conducting ferromagnets. We focus on a toy two-band model and on a four-band
spherical model which provides an approximate description of ferromagnetic
(Ga,Mn)As. These models are sufficiently simple that disorder-ladder-sum vertex
corrections to the long-wavelength spin-spin response function can be summed to
all orders. An important objective of this study is to assess the reliability
of practical approximate expressions which can be combined with electronic
structure calculations to estimate Gilbert damping in more complex systems.


title: X-ray stellar population of the LMC

abstract:
  In the study of stars, the high energy domain occupies a place of choice,
since it is the only one able to directly probe the most violent phenomena:
indeed, young pre-main sequence objects, hot massive stars, or X-ray binaries
are best revealed in X-rays. However, previously available X-ray observatories
often provided only crude information on individual objects in the Magellanic
Clouds. The advent of the highly efficient X-ray facilities XMM-Newton and
Chandra has now dramatically increased the sensitivity and the spatial
resolution available to X-ray astronomers, thus enabling a fairly easy
determination of the properties of individual sources in the LMC.


title:
A nanoflare model for active region radiance: application of artificial
  neural networks

abstract:
  Context. Nanoflares are small impulsive bursts of energy that blend with and
possibly make up much of the solar background emission. Determining their
frequency and energy input is central to understanding the heating of the solar
corona. One method is to extrapolate the energy frequency distribution of
larger individually observed flares to lower energies. Only if the power law
exponent is greater than 2, is it considered possible that nanoflares
contribute significantly to the energy input.
  Aims. Time sequences of ultraviolet line radiances observed in the corona of
an active region are modelled with the aim of determining the power law
exponent of the nanoflare energy distribution.
  Methods. A simple nanoflare model based on three key parameters (the flare
rate, the flare duration time, and the power law exponent of the flare energy
frequency distribution) is used to simulate emission line radiances from the
ions Fe XIX, Ca XIII, and Si iii, observed by SUMER in the corona of an active
region as it rotates around the east limb of the Sun. Light curve pattern
recognition by an Artificial Neural Network (ANN) scheme is used to determine
the values.
  Results. The power law exponents, alpha 2.8, 2.8, and 2.6 for Fe XIX, Ca
XIII, and Si iii respectively.
  Conclusions. The light curve simulations imply a power law exponent greater
than the critical value of 2 for all ion species. This implies that if the
energy of flare-like events is extrapolated to low energies, nanoflares could
provide a significant contribution to the heating of active region coronae.


title: On the Analyticity of Laguerre Series

abstract:
  The transformation of a Laguerre series $f (z) = \sum_{n=0}^{\infty}
\lambda_{n}^{(\alpha)} L_{n}^{(\alpha)} (z)$ to a power series $f (z) =
\sum_{n=0}^{\infty} \gamma_{n} z^{n}$ is discussed. Many nonanalytic functions
can be expanded in this way. Thus, success is not guaranteed. Simple sufficient
conditions based on the decay rates and sign patters of the
$\lambda_{n}^{(\alpha)}$ as $n \to \infty$ can be formulated which guarantee
that $f (z$ is analytic at $z=0$. Meaningful result are obtained if the
$\lambda_{n}^{(\alpha)}$ either decay exponentially or factorially as $n \to
\infty$. The situation is much more complicated if the $\lambda_{n}^{(\alpha)}$
decay algebraically as $n \to \infty$. If the $\lambda_{n}^{(\alpha)}$
ultimately have the same sign, the series expansions for the power series
coefficients diverge, and the corresponding function is not analytic at $z=0.
If the $\lambda_{n}^{(\alpha)}$ ultimately have strictly alternating signs, the
series expansions for the power series coefficients are summable and the power
series represents an analytic function. In the case of simple
$\lambda_{n}^{(\alpha)}$, the summation of the divergent series for the power
series coefficients can often be accomplished with the help of analytic
continuation formulas for hypergeometric series, but if the
$\lambda_{n}^{(\alpha)}$ are more complicated, numerical techniques have to be
employed. Certain nonlinear sequence transformations -- in particular the
so-called delta transformation [E. J. Weniger, Comput. Phys. Rep. \textbf{10},
189 -- 371 (1989), Eq. (8.4-4)] -- sum the divergent series occurring in this
context effectively.


title: Static and dynamic glass-glass transitions: a mean-field study

abstract:
  The behavior of a family of mean-field glass models is reviewed. The models
are analyzed by means of a Langevin-based approach to the dynamics and a
Replica theory computation of the thermodynamics. We focus on the phase diagram
of a particular model case, where glass-to-glass transitions occur between
phases with a different number of characteristic time-scales for the relaxation
processes. The appearence of Johari-Goldstein processes as collective
reorganizations of sets of fast processes is discussed.


title: On the strength of proof-irrelevant type theories

abstract:
  We present a type theory with some proof-irrelevance built into the
conversion rule. We argue that this feature is useful when type theory is used
as the logical formalism underlying a theorem prover. We also show a close
relation with the subset types of the theory of PVS. We show that in these
theories, because of the additional extentionality, the axiom of choice implies
the decidability of equality, that is, almost classical logic. Finally we
describe a simple set-theoretic semantics.


title: Direct Observation Limits on Antimatter Gravitation

abstract:
  The proposed Antihydrogen Gravity experiment at Fermilab (P981) will directly
measure the gravitational attraction ("gbar") between antihydrogen and the
Earth, with an accuracy of 1% or better. The following key question has been
asked by the PAC:
  Is a possible 1% difference between gbar and g already ruled out by other
evidence?
  This memo presents the key points of existing evidence, to answer whether
such a difference is ruled out (a) on the basis of direct observational
evidence; and/or (b) on the basis of indirect evidence, combined with reasoning
based on strongly held theoretical assumptions. The bottom line is that there
are no direct observations or measurements of gravitational asymmetry which
address the antimatter sector. There is evidence which by indirect reasoning
can be taken to rule out such a difference, but the analysis needed to draw
that conclusion rests on models and assumptions which are in question for other
reasons and are thus worth testing. There is no compelling evidence or
theoretical reason to rule out such a difference at the 1% level.


title:
Local transfer and spectra of a diffusive field advected by large-scale
  incompressible flows

abstract:
  This study revisits the problem of advective transfer and spectra of a
diffusive scalar field in large-scale incompressible flows in the presence of a
(large-scale) source. By ``large-scale'' it is meant that the spectral support
of the flows is confined to the wave-number region $k<k_d$, where $k_d$ is
relatively small compared with the diffusion wave number $k_\kappa$. Such flows
mediate couplings between neighbouring wave numbers within $k_d$ of each other
only. It is found that the spectral rate of transport (flux) of scalar variance
across a high wave number $k>k_d$ is bounded from above by $Uk_dk\Theta(k,t)$,
where $U$ denotes the maximum fluid velocity and $\Theta(k,t)$ is the spectrum
of the scalar variance, defined as its average over the shell $(k-k_d,k+k_d)$.
For a given flux, say $\vartheta>0$, across $k>k_d$, this bound requires
$$\Theta(k,t)\ge \frac{\vartheta}{Uk_d}k^{-1}.$$ This is consistent with recent
numerical studies and with Batchelor's theory that predicts a $k^{-1}$ spectrum
(with a slightly different proportionality constant) for the viscous-convective
range, which could be identified with $(k_d,k_\kappa)$. Thus, Batchelor's
formula for the variance spectrum is recovered by the present method in the
form of a critical lower bound. The present result applies to a broad range of
large-scale advection problems in space dimensions $\ge2$, including some
filter models of turbulence, for which the turbulent velocity field is advected
by a smoothed version of itself. For this case, $\Theta(k,t)$ and $\vartheta$
are the kinetic energy spectrum and flux, respectively.


title:
Radio-frequency induced ground state degeneracy in a Chromium
  Bose-Einstein condensate

abstract:
  We study the effect of strong radio-frequency (rf) fields on a chromium
Bose-Einstein condensate (BEC), in a regime where the rf frequency is much
larger than the Larmor frequency. We use the modification of the Land\'{e}
factor by the rf field to bring all Zeeman states to degeneracy, despite the
presence of a static magnetic field of up to 100 mG. This is demonstrated by
analyzing the trajectories of the atoms under the influence of dressed magnetic
potentials in the strong field regime. We investigate the problem of
adiabaticity of the rf dressing process, and relate it to how close the dressed
states are to degeneracy. Finally, we measure the lifetime of the rf dressed
BECs, and identify a new rf-assisted two-body loss process induced by
dipole-dipole interactions.


title: Nonlinear transmission through a tapered fiber in rubidium vapor

abstract:
  Sub-wavelength diameter tapered optical fibers surrounded by rubidium vapor
can undergo a substantial decrease in transmission at high atomic densities due
to the accumulation of rubidium atoms on the surface of the fiber. Here we
demonstrate the ability to control these changes in transmission using light
guided within the taper. We observe transmission through a tapered fiber that
is a nonlinear function of the incident power. This effect can also allow a
strong control beam to change the transmission of a weak probe beam.


title:
Spectrum of $\pi$ Electrons in Graphene as an Alternant Macromolecule
  and Its Specific Features in Quantum Conductance

abstract:
  An exact description of $\pi$ electrons based on the tight-binding model of
graphene as an alternant, plane macromolecule is presented. The model molecule
can contain an arbitrary number of benzene rings and has armchair- and
zigzag-shaped edges. This suggests an instructive alternative to the most
commonly used approach, where the reference is made to the honeycomb lattice
periodic in its A and B sublattices. Several advantages of the macromolecule
model are demonstrated. The newly derived analytical relations detail our
understanding of $\pi$ electron nature in achiral graphene ribbons and carbon
tubes and classify these structures as quantum wires.


title: Simulating the All-Order Strong Coupling Expansion I: Ising Model Demo

abstract:
  We investigate in some detail an alternative simulation strategy for lattice
field theory based on the so-called worm algorithm introduced by Prokof'ev and
Svistunov in 2001. It amounts to stochastically simulating the strong coupling
expansion rather than the usual configuration sum. A detailed error analysis
and an important generalization of the method are exemplified here in the
simple Ising model. It allows for estimates of the two point function where in
spite of exponential decay the signal to noise ratio does not degrade at large
separation. Critical slowing down is practically absent. In the outlook some
thoughts on the general applicability of the method are offered.


title: A sectional characterization of the Dade group

abstract:
  Let $k$ be a field of characteristic $p$, let $P$ be a finite $p$- group,
where $p$ is an odd prime, and let $D(P)$ be the Dade group of endo-permutation
$kP$-modules. It is known that $D(P)$ is detected via deflation--restriction by
the family of all sections of $P$ which are elementary abelian of rank $\leq2$.
In this paper, we improve this result by characterizing $D(P)$ as the limit
(with respect to deflation--restriction maps and conjugation maps) of all
groups $D(T/S)$ where $T/S$ runs through all sections of $P$ which are either
elementary abelian of rank $\leq3$ or extraspecial of order $p^3$ and exponent
$p$.


title: Reheating in a Brane Monodromy Inflation Model

abstract:
  We study reheating in a recently proposed brane "monodromy inflation" model
in which the inflaton is the position of a D4 brane on a "twisted torus".
Specifically, we study the repeated collisions between the D4 brane and a D6
brane (on which the Standard Model fields are assumed to be localized) at a
fixed position along the monodromy direction as the D4 brane rolls down its
potential. We find that there is no trapping of the rolling D4 brane until it
reaches the bottom of its potential, and that reheating is entirely described
by the last brane encounter. Previous collisions have negligible effect on the
brane velocity and hence on the reheat temperature. In the context of our
setup, reheating is efficient and the reheat temperature is therefore high.


title:
Understanding Fairness and its Impact on Quality of Service in IEEE
  802.11

abstract:
  The Distributed Coordination Function (DCF) aims at fair and efficient medium
access in IEEE 802.11. In face of its success, it is remarkable that there is
little consensus on the actual degree of fairness achieved, particularly
bearing its impact on quality of service in mind. In this paper we provide an
accurate model for the fairness of the DCF. Given M greedy stations we assume
fairness if a tagged station contributes a share of 1/M to the overall number
of packets transmitted. We derive the probability distribution of fairness
deviations and support our analytical results by an extensive set of
measurements. We find a closed-form expression for the improvement of long-term
over short-term fairness. Regarding the random countdown values we quantify the
significance of their distribution whereas we discover that fairness is largely
insensitive to the distribution parameters. Based on our findings we view the
DCF as emulating an ideal fair queuing system to quantify the deviations from a
fair rate allocation. We deduce a stochastic service curve model for the DCF to
predict packet delays in IEEE 802.11. We show how a station can estimate its
fair bandwidth share from passive measurements of its traffic arrivals and
departures.


title:
On a surprising relation between the Marchenko-Pastur law, rectangular
  and square free convolutions

abstract:
  n this paper, we prove a result linking the square and the rectangular
R-transforms, the consequence of which is a surprising relation between the
square and rectangular versions the free additive convolutions, involving the
Marchenko-Pastur law. Consequences on random matrices, on infinite divisibility
and on the arithmetics of the square versions of the free additive and
multiplicative convolutions are given.


title:
Study of ionization signals in a TPC filled with a mixture of liquid
  Argon and Nitrogen

abstract:
  In this paper we report on the evidence for ionization track signals from
cosmic ray muons and Compton electrons in a Time Projection Chamber (TPC)
filled with liquid Argon and doped with different fractions of Nitrogen. This
study has been conducted in view of the possible use of liquid Argon/Nitrogen
TPCs for the detection of gamma rays in the resonant band of the Nitrogen
absorbtion spectrum, a promising technology for security and medical
applications.


title: Ion-Size Effect at the Surface of a Silica Hydrosol

abstract:
  The author used synchrotron x-ray reflectivity to study the ion-size effect
for alkali ions (Na$^+$, K$^+$, Rb$^+$, and Cs$^+$), with densities as high as
$4 \times 10^{18}- 7 \times 10^{18}$ m$^{-2}$, suspended above the surface of a
colloidal solution of silica nanoparticles in the field generated by the
surface electric-double layer. According to the data, large alkali ions
preferentially accumulate at the sol's surface replacing smaller ions, a
finding that qualitatively agrees with the dependence of the Kharkats-Ulstrup
single-ion electrostatic free energy on the ion's radius.


title: On the interaction between two Kerr black holes

abstract:
  The double-Kerr solution is generated using both a Backlund transformation
and the Belinskii-Zakharov inverse-scattering technique. We build a dictionary
between the parametrisations naturally obtained in the two methods and show
their equivalence. We then focus on the asymptotically flat double-Kerr system
obeying the axis condition which is Z_2^\phi invariant; for this system there
is an exact formula for the force between the two black holes, in terms of
their physical quantities and the coordinate distance. We then show that 1) the
angular velocity of the two black holes decreases from the usual Kerr value at
infinite distance to zero in the touching limit; 2) the extremal limit of the
two black holes is given by |J|=cM^2, where c depends on the distance and
varies from one to infinity as the distance decreases; 3) for sufficiently
large angular momentum the temperature of the black holes attains a maximum at
a certain finite coordinate distance. All of these results are interpreted in
terms of the dragging effects of the system.


title: Chemical probing spectroscopy of H3+ above the barrier to linearity

abstract:
  We have performed chemical probing spectroscopy of H3+ ions trapped in a
cryogenic 22-pole ion trap. The ions were buffer-gas cooled to 55K by
collisions with helium and argon. Excitation to states above the barrier to
linearity was achieved by a Ti:Sa laser operated between 11300 and 13300 cm-1.
Subsequent collisions of the excited H3+ ions with argon lead to the formation
of ArH+ ions that were detected by a quadrupole mass spectrometer with high
sensitivity. We report the observation of 17 previously unobserved transitions
to states above the barrier to linearity. Comparison to theoretical
calculations suggests that the transition strengths of some of these lines are
more than five orders of magnitude smaller than those of the fundamental band,
which renders them - to the best of our knowledge - the weakest H3+ transitions
observed to date.


title: Conservation Laws and Non-Lie Symmetries

abstract:
  We introduce a method to construct conservation laws for a large class of
linear partial differential equations. In contrast to the classical result of
Noether, the conserved currents are generated by any symmetry of the operator,
including those of the non-Lie type. An explicit example is made of the Dirac
equation were we use our construction to find a class of conservation laws
associated with a 64 dimensional Lie algebra of discrete symmetries that
includes CPT.


title:
Investigations of the magnetospheric plasma distribution in the vicinity
  of a pulsar - I Basic formulation

abstract:
  The magnetospheric plasma distribution in the vicinity of a pulsar at various
inclination angles is investigated using a new relativistic, parallel 3D
Particle-In-Cell (PIC) code DYMPHNA3D. DYMPHNA3D uses a superposition of the
electromagnetic fields associated with a rotating magnetised conducting sphere
in a vacuum (the pulsar fields) and the electromagnetic fields due to the
presence of the magnetospheric plasma surrounding the pulsar (the plasma
fields), as the total fields. The plasma is moved self-consistently through the
magnetosphere using the PIC methodology. Our initial simulation results are
presented here. These show similar solutions to those obtained from previous
numerical simulations, which show the fundamental plasma distribution in the
vicinity of an aligned rotating neutron star to consist of two polar domes and
an equatorial torus of trapped non-neutral plasma of opposite sign. The aligned
case being the case in which the inclination angle between the magnetic dipole
moment and the rotation axis of the star is zero. Furthermore, our code allows
for off-axis simulations and we have found that this plasma distribution
collapses into a Quad-Lobe charge-separated non-neutral magnetospheric plasma
distribution in the case of an orthogonal rotator, i.e., the case in which the
magnetic dipole moment is oriented at right angles to the rotation axis of the
neutron star, with the plasma remaining trapped close to the stellar surface by
the force-free surfaces. We find that if initialised with a Goldreich-Julian
type distribution, the system is seen to collapse rapidly into these stable
Dome-Torus structures.


title:
CFT adapted gauge invariant formulation of arbitrary spin fields in AdS
  and modified de Donder gauge

abstract:
  Using Poincare parametrization of AdS space, we study totally symmetric
arbitrary spin massless fields in AdS space of dimension greater than or equal
to four. CFT adapted gauge invariant formulation for such fields is developed.
Gauge symmetries are realized similarly to the ones of Stueckelberg formulation
of massive fields. We demonstrate that the curvature and radial coordinate
contributions to the gauge transformation and Lagrangian of the AdS fields can
be expressed in terms of ladder operators. Realization of the global AdS
symmetries in the conformal algebra basis is obtained. Modified de Donder gauge
leading to simple gauge fixed Lagrangian is found. The modified de Donder gauge
leads to decoupled equations of motion which can easily be solved in terms of
Bessel function. Interrelations between our approach to the massless AdS fields
and the Stueckelberg approach to massive fields in flat space are discussed.


title: Electric excitation of spin resonance in antiferromagnetic conductors

abstract:
  Antiferromagnetism couples electron spin to its orbital motion, thus allowing
excitation of electron-spin transitions by an ac electric rather than magnetic
field - with absorption, exceeding that of common electron spin resonance at
least by four orders of magnitude. In addition to potential applications in
spin electronics, this phenomenon may be used as a spectroscopy to study
antiferromagnetic materials of interest - from chromium to borocarbides,
cuprates, iron pnictides, and organic and heavy fermion conductors.


title: The effects of stochastic population dynamics on food web structure

abstract:
  We develop a stochastic, individual-based model for food web simulation which
in the large-population limit reduces to the well-studied Webworld model, which
has been used to successfully construct model food webs with several realistic
features. We demonstrate that an almost exact match is found between the
population dynamics in fixed food webs, and that the demographic fluctuations
have systematic effects when the new model is used to construct food webs due
to the presence of species with small populations.


title:
The doping-driven evolution of the superconducting state of a doped Mott
  insulator: a key for the high temperature superconductivity

abstract:
  High-temperature superconductors at zero doping can be considered strongly
correlated two-dimensional Mott insulators. The understanding of the connection
between the superconductor and the Mott insulator hits at the heart of the
high-temperature superconducting mechanism. In this paper we investigate the
zero-temperature doping-driven evolution of a superconductor towards the Mott
insulator in a two dimensional electron model, relevant for high temperature
superconductivity. To this purpose we use a cluster extension of dynamical mean
field theory. Our results show that a standard (BCS) d-wave superconductor,
realized at high doping, is driven into the Mott insulator via an intermediate
state displaying non-standard physical properties. By restoring the
translational invariance of the lattice, we give an interpretation of these
findings in momentum space. In particular, we show that at a finite doping a
strong momentum-space differentiation takes place: non-Fermi liquid and
insulating-like (pseudogap) character rises in some regions (anti-nodes), while
Fermi liquid quasiparticles survive in other regions (nodes) of momentum space.
We describe the consequence of these happenings on the spectral properties,
stressing in particular the behavior of the superconducting gap, which reveals
two distinct nodal and antinodal energy scales as a function of doping. We
propose a description of the evolution of the electronic structure while
approaching the Mott transition and compare our results with tunneling
experiments, photoemission and magnetotransport on cuprate materials.


title: Thulium environment in a silica doped optical fibre

abstract:
  Thulium-doped optical fibre amplifiers (TDFA) are developed to extend the
optical telecommunication wavelength division multiplexing (WDM) bandwidth in
the so-called S-band (1460-1530 nm). The radiative transition at 1.47 lm (3H4
-> 3F4) competes with a non-radiative multi-phonon de-excitation (3H4 -> 3H5).
The quantum efficiency of the transition of interest is then highly affected by
the phonon energy (Ep) of the material. For reliability reasons, oxide glasses
are preferred but suffer from high phonon energy. In the case of silica glass,
Ep is around 1100 cm-1 and quantum efficiency is as low as 2%. To improve it,
phonon energy in the thulium environment must be lowered. For that reason,
aluminium is added and we explore three different core compositions: pure
silica, and silica slightly modified with germanium or phosphorus. The role of
aluminium is studied through fluorescence decay curves, fitted according to the
continuous function decay analysis. From this analysis, modification of the
thulium local environment due to aluminium is evidenced.


title: The Swift capture of a long X-ray burst from XTE J1701-407

abstract:
  XTE J1701-407 is a new transient X-ray source discovered on June 8th, 2008.
More than one month later it showed a rare type of thermonuclear explosion: a
long type I X-ray burst. We report herein the results of our study of the
spectral and flux evolution during this burst, as well as the analysis of the
outburst in which it took place. We find an upper limit on the distance to the
source of 6.1 kpc by considering the maximum luminosity reached by the burst.
We measure a total fluence of 3.5*10^{-6} erg/cm^2 throughout the ~20 minutes
burst duration and a fluence of 2.6*10^{-3} erg/cm^2 during the first two
months of the outburst. We show that the flux decay is best fitted by a power
law (index ~1.6) along the tail of the burst. Finally, we discuss the
implications of the long burst properties, and the presence of a second and
shorter burst detected by Swift ten days later, for the composition of the
accreted material and the heating of the burning layer.


title:
A Pearson Effective Potential for Monte-Carlo simulation of quantum
  confinement effects in various MOSFET architectures

abstract:
  A Pearson Effective Potential model for including quantization effects in the
simulation of nanoscale nMOSFETs has been developed. This model, based on a
realistic description of the function representing the non zero-size of the
electron wave packet, has been used in a Monte-Carlo simulator for bulk, single
gate SOI and double-gate SOI devices. In the case of SOI capacitors, the
electron density has been computed for a large range of effective field
(between 0.1 MV/cm and 1 MV/cm) and for various silicon film thicknesses
(between 5 nm and 20 nm). A good agreement with the Schroedinger-Poisson
results is obtained both on the total inversion charge and on the electron
density profiles. The ability of an Effective Potential approach to accurately
reproduce electrostatic quantum confinement effects is clearly demonstrated.


title: Flavor Data Constraints on the SUSY Parameter Space

abstract:
  We present an overview of the indirect constraints from flavor physics on
supersymmetric models. During the past few years flavor data, and in particular
b -> s gamma transitions, have been extensively used in order to constrain
supersymmetric parameter spaces. We will briefly illustrate here the
constraints obtained by a collection of low energy observables including FCNC
transitions, rare decays, leptonic and semileptonic decays of B mesons, as well
as leptonic decays of K mesons. The theoretical predictions can be obtained
using the computer program SuperIso.


title: Comments on Fermi Liquid from Holography

abstract:
  We investigate the signatures of Fermi liquid formation in the N=4 super
Yang-Mills theory coupled to fundamental hypermultiplet at nonvanishing
chemical potential for the global U(1) vector symmetry. At strong 't Hooft
coupling the system can be analyzed in terms of the D7 brane dynamics in AdS_5
x S^5 background. The phases with vanishing and finite charge density are
separated at zero temperature by a quantum phase transition. In case of
vanishing hypermultiplet mass, Karch, Son and Starinets discovered a gapless
excitation whose speed equals the speed of sound. We find that this zero sound
mode persists to all values of the hypermultiplet mass, and its speed vanishes
at the point of phase transition. The value of critical exponent and the ratio
of the velocities of zero and first sounds are consistent with the predictions
of Landau Fermi liquid theory at strong coupling.


title:
Emerging attractors and the transition from dissipative to conservative
  dynamics

abstract:
  The topological structure of basin boundaries plays a fundamental role in the
sensitivity to the initial conditions in chaotic dynamical systems. Herewith we
present a study on the dynamics of dissipative systems close to the Hamiltonian
limit, emphasising the increasing number of periodic attractors and on the
structural changes in their basin boundaries as the dissipation approaches
zero. We show numerically that a power law with nontrivial exponent describes
the growth of the total number of periodic attractors as the damping is
decreased. We also establish that for small scales the dynamics is governed by
\emph{effective} dynamical invariants, whose measure depends not only on the
region of the phase space, but also on the scale under consideration.
Therefore, our results show that the concept of effective invariants is also
relevant for dissipative systems.


title: Magnetoelectric coupling in the cubic ferrimagnet Cu2OSeO3

abstract:
  We have investigated the magnetoelectric coupling in the lone pair containing
piezoelectric ferrimagnet Cu2OSeO3. Significant magnetocapacitance develops in
the magnetically ordered state (TC = 60 K). We find critical behavior near TC
and a divergence near the metamagnetic transition at 500 Oe. High-resolution
X-ray and neutron powder diffraction measurements show that Cu2OSeO3 is
metrically cubic down to 10 K but that the ferrimagnetic ordering reduces the
symmetry to rhombohedral R3. The metric cubic lattice dimensions exclude a
magnetoelectric coupling mechanism involving spontaneous lattice strain, and
this is unique among magnetoelectric and multiferroic materials.


title: Resonance and limit cycle in a noise driven Lorenz model

abstract:
  The effect of an external noise on the Lorenz model is investigated near the
onset of convection and near the Hopf bifurcation. We show the existence of a
diverging time scale near the onset of convection and a resonance near the Hopf
bifurcation. Our calculation provides an understanding of the noise induced
stabilization of the limit cycle that had been observed numerically.


title: Pulsations of the Low Mass ZZ Ceti Star HS 1824+6000

abstract:
  Measuring g-mode pulsations of isolated white dwarfs can reveal their
interior properties to high precision. With a spectroscopic mass of ~0.51
M_{\odot} (log g = 7.82), the DAV white dwarf HS 1824+6000 is near the
transition between carbon/oxygen core and helium core white dwarfs, motivating
our photometric search for additional pulsations from the Palomar 60-inch
telescope. We confirmed (with much greater precision) the three frequencies:
2.751190 +/- 0.000010 mHz (363.479 sec), 3.116709 +/- 0.000006 mHz (320.851
sec), 3.495113 +/- 0.000009 mHz (286.114 sec), previously found by B. Voss and
collaborators, and found an additional pulsation at 4.443120 +/- 0.000012 mHz
(225.067 sec). These observed frequencies are similar to those found in other
ZZ Ceti white dwarfs of comparable mass (e.g. log g < 8). We hope that future
observations of much lower mass ZZ Ceti stars (< 0.4 M_{\odot}) will reveal
pulsational differences attributable to a hydrogen covered helium core.


title:
Calibrating a novel type of bolometer arrays for the Herschel/PACS
  Photometer

abstract:
  The Herschel Space Observatory is a corner stone mission of the European
Space Agency (ESA) scientific program. With its spatial resolution, sensitivity
and spectral range (60 to 670 microns) Herschel will provide astronomers with
unique opportunities to decipher many aspects of star formation mecanisms and
galaxy evolution.
  Among the many research institutes involved in the development and
exploitation of this challenging observatory, the Commissariat a l'Energie
Atomique (CEA) designed a novel type of bolometric detectors to equip the
photometer of the PACS instrument on-board the Herschel satellite.
  In this thesis, I present the basics of infrared astronomy and past and
present developments in cryogenic bolometers, emphasising on new concepts
introduced by CEA, that is the collective manufacturing of bolometer arrays,
the high impedance thermometers, the cold multiplexing and the use of a
resonant cavity to optimize absorption of electromagnetic radiation. I follow
with an in-depth explanation of the working principles of CEA bolometer arrays,
a prerequisite to grasp the strategy of the characterisation procedure that we
developed. I then expose and analyse thoroughly the results that we obtained
during the calibration campaign of the PACS photometer. Finally, I express
detector performances in terms of "observational" performances that future PACS
users can comprehend (time constant -> PSF smearing, NEP -> sensitivity, etc.).


title: A Simple Extension of the $\modulo$-$\Lambda$ Transformation

abstract:
  A simple lemma is derived that allows to transform a general scalar
(non-Gaussian, non-additive) continuous-alphabet channel as well as a general
multiple-access channel into a modulo-additive noise channel. While in general
the transformation is information lossy, it allows to leverage linear coding
techniques and capacity results derived for networks comprised of additive
Gaussian nodes to more general networks.


title: A lower bound on the dimension of a quantum system given measured data

abstract:
  We imagine an experiment on an unknown quantum mechanical system in which the
system is prepared in various ways and a range of measurements are performed.
For each measurement M and preparation rho the experimenter can determine,
given enough time, the probability of a given outcome a: p(a|M,rho). How large
does the Hilbert space of the quantum system have to be in order to allow us to
find density matrices and measurement operators that will reproduce the given
probability distribution? In this note, we prove a simple lower bound for the
dimension of the Hilbert space. The main insight is to relate this problem to
the construction of quantum random access codes, for which interesting bounds
on Hilbert space dimension already exist. We discuss several applications of
our result to hidden variable, or ontological models, to Bell inequalities and
to properties of the smooth min-entropy.


title:
Central Production with Tagged Forward Protons and the Star Detector at
  RHIC

abstract:
  We describe a setup which will allow extend the physics reach of the STAR
detector at RHIC to include the measurement of very forward protons. Tagging on
very forward protons, detected by the Roman Pots at RHIC energies, selects
processes, in which the proton stays intact and the exchange is dominated by
one with the quantum numbers of the vacuum, thus enhancing the probability of
measuring reactions where colorless gluonic matter dominates the exchange. The
processes include both elastic and inelastic diffraction. The capabilities of
the STAR detector to detect Gleuballs and Exotics in central production
mechanism are described.


title: Optical Diffraction Radiation from a beam off a circular target

abstract:
  We calculate the optical diffraction radiation generated by a bunch of high
energy particles as they pass through a round hole within an annular metallic
ring. We derive expressions for the differential angular spectrum in the
far-field and the intensities of the horizontal and vertical polarizations. The
sensitivity of the spectrum to changes in beam size and position is shown. The
total photon yield from the bunch is calculated and used to set limits on the
detectable wavelengths.


title:
Comment on 'Evolution of the unidirectional electromagnetic pulses in an
  anisotropic two-level medium'

abstract:
  Recently, Zabolotskii [Phys. Rev. E 77, 036603 (2008)] presented the Lax pair
for a version of the reduced Maxwell--Bloch equations. This version was derived
under considering the unidirectional propagation of a two-component
electromagnetic pulse through an anisotropic two-level medium. We demonstrate
that his derivation contains essential omission, which led to the wrong version
of the reduced Maxwell--Bloch equations. We also point out that the Lax pair
for correct version of these equations had been known in the most general
anisotropic case.


title: A Cubical Set Approach to 2-Bundles with Connection and Wilson Surfaces

abstract:
  In the context of non-abelian gerbes we define a cubical version of
categorical group 2-bundles with connection over a smooth manifold. We define
their two-dimensional parallel transport, study its properties, and define
non-abelian Wilson surface functionals.


title: Hadrons in Strong Electric and Magnetic Fields

abstract:
  We use chiral perturbation theory to investigate hadronic properties in
strong electric and magnetic fields. A strong-field power counting is employed,
and results for pions and nucleons are obtained using Schwinger's proper-time
method. In the limit of weak fields, we accordingly recover the well known
one-loop chiral perturbation theory results for the electric and magnetic
polarizabilities of pions and nucleons. In strong constant fields, we extend
the Gell-Mann-Oakes-Renner relation. For the case of electric fields, we find
that non-perturbative effects result in hadron decay. For sufficiently strong
magnetic fields, the chiral analysis confirms that the nucleon hierarchy
becomes inverted giving rise to proton beta-decay. Properties of asymptotic
expansions are explored by considering weak field limits. In the regime where
the perturbative expansion breaks down, the first-order term gives the best
agreement with the non perturbative result.


title: On the Direction of Casimir Forces

abstract:
  The Casimir force due to a massless scalar field satisfying Dirichlet
boundary conditions may attract or repel a piston in the neck of a flask-like
container. Using the world-line formalism this behavior is related to the
competing contribution to the interaction energy of two types of Brownian
bridges. It qualitatively is also expected from attractive long-range two-body
forces between constituents of the boundary. A geometric subtraction scheme is
presented that avoids divergent contributions to the interaction energy and
classifies the Brownian bridges that contribute to the force. These are all of
finite length and the Casimir force can be analyzed and in principle accurately
computed without resorting to regularization or analytic continuation. The
world-line analysis is robust with respect to variations in the shape of the
piston and the flask and the analogy with long-range forces suggests that
neutral atoms and particles are also drawn into open-ended pipes (or
nano-tubes) by Casimir forces of electromagnetic origin.


title: Feshbach resonances in an ultracold $^7$Li and $^{87}$Rb mixture

abstract:
  We report on the observation of five Feshbach resonances in collisions
between ultracold $^7$Li and $^{87}$Rb atoms in the absolute ground state
mixture where both species are in their $|f,m_f>=|1,1>$ hyperfine states. The
resonances appear as trap losses for the $^7$Li cloud induced by inelastic
heteronuclear three-body collisions. The magnetic field values where they occur
are important quantities for an accurate determination of the interspecies
interaction potentials. Results of coupled channels calculations based on the
observed resonances are presented and refined potential parameters are given. A
very broad Feshbach resonance centered around 649 G should allow for fine
tuning of the interaction strength in future experiments.


title:
XAX: a multi-ton, multi-target detection system for dark matter, double
  beta decay and pp solar neutrinos

abstract:
  A multi-target detection system XAX, comprising concentric 10 ton targets of
136Xe and 129/131Xe, together with a geometrically similar or larger target of
liquid Ar, is described. Each is configured as a two-phase
scintillation/ionization TPC detector, enhanced by a full 4pi array of
ultra-low radioactivity Quartz Photon Intensifying Detectors (QUPIDs) replacing
the conventional photomultipliers for detection of scintillation light. It is
shown that background levels in XAX can be reduced to the level required for
dark matter particle (WIMP) mass measurement at a 10^-10 pb WIMP-nucleon cross
section, with single-event sensitivity below 10^-11 pb. The use of multiple
target elements allows for confirmation of the A^2 dependence of a coherent
cross section, and the different Xe isotopes provide information on the
spin-dependence of the dark matter interaction. The event rates observed by Xe
and Ar would modulate annually with opposite phases from each other for WIMP
mass >~100 GeV/c^2. The large target mass of 136Xe and high degree of
background reduction allow neutrinoless double beta decay to be observed with
lifetimes of 10^27-10^28 years, corresponding to the Majorana neutrino mass
range 0.01-0.1 eV, the most likely range from observed neutrino mass
differences. The use of a 136Xe-depleted 129/131Xe target will also allow
measurement of the pp solar neutrino spectrum to a precision of 1-2%.


title:
Suppression of forward dilepton production from an anisotropic
  quark-gluon plasma

abstract:
  We calculate the rapidity dependence of leading-order medium dilepton yields
resulting from a quark-gluon plasma which has a local time-dependent anisotropy
in momentum space. We present a phenomenological model which includes temporal
evolution of the plasma anisotropy parameter, xi, and the hard momentum scale,
p_hard. Our model interpolates between 1+1 dimensional collisionally-broadened
expansion at early times and 1+1 dimensional ideal hydrodynamic expansion at
late times. Using our model, we find that at LHC energies, forward high-energy
medium dilepton production would be suppressed by up to a factor of 3 if one
assumes an isotropization/thermalization time of 2 fm/c. Therefore, it may be
possible to use forward dilepton yields to experimentally determine the time of
onset of locally isotropic hydrodynamic expansion of the quark-gluon plasma as
produced in ultrarelativistic heavy-ion collisions.


title:
Generators and defining relations for ring of differential operators on
  smooth affine algebraic variety in prime characteristic

abstract:
  For ring of differential operators on smooth affine algebraic variety over
perfect field of prime characteristic a set of algebra generators and a set of
defining relations are found explicitly.


title: Networked MIMO with Clustered Linear Precoding

abstract:
  A clustered base transceiver station (BTS) coordination strategy is proposed
for a large cellular MIMO network, which includes full intra-cluster
coordination to enhance the sum rate and limited inter-cluster coordination to
reduce interference for the cluster edge users. Multi-cell block
diagonalization is used to coordinate the transmissions across multiple BTSs in
the same cluster. To satisfy per-BTS power constraints, three combined precoder
and power allocation algorithms are proposed with different performance and
complexity tradeoffs. For inter-cluster coordination, the coordination area is
chosen to balance fairness for edge users and the achievable sum rate. It is
shown that a small cluster size (about 7 cells) is sufficient to obtain most of
the sum rate benefits from clustered coordination while greatly relieving
channel feedback requirement. Simulations show that the proposed coordination
strategy efficiently reduces interference and provides a considerable sum rate
gain for cellular MIMO networks.


title:
Stability of roots of polynomials under linear combinations of
  derivatives

abstract:
  Let $T=\alpha_0 I + \alpha_1 D + ...+\alpha_n D^n$, where $D$ is the
differentiation operator and $\alpha_0\not= 0$, and let $f$ be a square-free
polynomial with large minimum root separation. We prove that the roots of $Tf$
are close to the roots of $f$ translated by $-\alpha_1/\alpha_0$.


title:
Randomized benchmarking of single and multi-qubit control in
  liquid-state NMR quantum information processing

abstract:
  Being able to quantify the level of coherent control in a proposed device
implementing a quantum information processor (QIP) is an important task for
both comparing different devices and assessing a device's prospects with
regards to achieving fault-tolerant quantum control. We implement in a
liquid-state nuclear magnetic resonance QIP the randomized benchmarking
protocol presented by Knill et al (PRA 77: 012307 (2008)). We report an error
per randomized $\frac{\pi}{2}$ pulse of $1.3 \pm 0.1 \times 10^{-4}$ with a
single qubit QIP and show an experimentally relevant error model where the
randomized benchmarking gives a signature fidelity decay which is not possible
to interpret as a single error per gate. We explore and experimentally
investigate multi-qubit extensions of this protocol and report an average error
rate for one and two qubit gates of $4.7 \pm 0.3 \times 10^{-3}$ for a three
qubit QIP. We estimate that these error rates are still not decoherence limited
and thus can be improved with modifications to the control hardware and
software.


title: Anti-Perfect Morse Stratification

abstract:
  For an equivariant Morse stratification which contains a unique open stratum,
we introduce the notion of equivariant antiperfection, which means the
difference of the equivariant Morse series and the equivariant Poincare series
achieves the maximal possible value (instead of the minimal possible value 0 in
the equivariantly perfect case). We also introduce a weaker condition of local
equivariant antiperfection. We prove that the Morse stratification of the
Yang-Mills functional on the space of connections on a principal U(n)-bundle
over a connected, closed, nonorientable surface is locally equivariantly
Q-antiperfect when the rank n=2,3; we propose that it is actually equivariantly
Q-antiperfect when n=2,3. Our proposal yields formulas of G-equivariant
Poincare series of the representation variety of flat G-connections for the
nonorientable surface where G=U(2), SU(2), U(3), SU(3). Our rank 2 formulas
agree with formulas proved by T. Baird in arXiv:0806.1975.
  Baird verified our conjectural rank 3 formulas when the nonorientable surface
is the real projective plane or the Klein bottle (arXiv:0901.1604); he proved
our conjectural U(3) formula for any closed nonorientable surfaces by
establishing equivariant Q-antiperfection in this case (arXiv:0902.4581).


title:
Monte Carlo simulation of the experiment MAMBO I and possible correction
  of neutron lifetime result

abstract:
  We are discussing the present situation with neutron lifetime measurements.
There is a serious discrepancy between the previous experiments and the recent
precise experiment [1]. The possible reason of the discrepancy can be connected
with a quasi-elastic scattering of UCN on the surface of liquid fomblin which
was used for most of the previous experiments. The Monte Carlo simulation of
one of the previous experiments [2] shows that the result of this experiment
[2] has to be corrected and instead of the previous result 887.6 +/- 3 s the
new result 880.4 +/- 3 s has to be claimed. [1] A.P. Serebrov et al., Phys.
Lett. B 605 (2005) 72. [2] W. Mampe et al., Phys. Rev. Lett. 63 (1989) 593.


title:
Interacting particles in two dimensions: numerical solution of the
  four-dimensional Schr\"odinger equation in a hypercube

abstract:
  We study numerically the Coulomb interacting two-particle stationary states
of the Schr\"odinger equation, where the particles are confined in a
two-dimensional infinite square well. Inside the domain the particles are
subjected to a steeply increasing isotropic harmonic potential, resembling that
in a nucleus. For these circumstances we have developed a fully discretized
finite difference method of the Numerov-type that approximates the
four-dimensional Laplace operator, and thus the whole Schr\"odinger equation,
with a local truncation error of $\mathcal{O}(h^6)$, with $h$ being the uniform
step size. The method is built on a 89-point central difference scheme in the
four-dimensional grid. As expected from the general theorem by Keller [Num.\
Math. \textbf{7}, 412 (1965)], the error of eigenvalues so obtained are found
to be the same order of magnitude which we have proved analytically as well.


title: The Soft-Wall Standard Model

abstract:
  We explore the possibility of modeling electroweak physics in a warped extra
dimension with a soft wall. The infrared boundary is replaced with a smoothly
varying dilaton field that provides a dynamical spacetime cutoff. We analyze
gravity, gauge fields, and fermions in the soft-wall background and obtain a
discrete spectrum of Kaluza-Klein states which can exhibit linear Regge-like
behavior. Bulk Yukawa interactions give rise to nonconstant fermion mass terms,
leading to fermion localization in the soft-wall background and a possible
explanation of the Standard Model flavor structure. Furthermore we construct
electroweak models with custodial symmetry, where the gauge symmetry is broken
with a bulk Higgs condensate. The electroweak constraints are not as stringent
as in hard-wall models, allowing Kaluza-Klein masses of order the TeV scale.


title:
Preparation of facilities for fundamental research with ultracold
  neutrons at PNPI

abstract:
  The WWR-M reactor of PNPI offers a unique opportunity to prepare a source for
ultracold neutrons (UCN) in an environment of high neutron flux (about 3*10^12
n/cm^2/s) at still acceptable radiation heat release (about 4*10^-3 W/g). It
can be realized within the reactor thermal column situated close to the reactor
core. With its large diameter of 1 m, this channel allows to install a 15 cm
thick bismuth shielding, a graphite premoderator (300 dm^3 at 20 K), and a
superfluid helium converter (35 dm^3). At a temperature of 1.2 K it is possible
to remove the heat release power of about 20 W. Using the 4pi flux of cold
neutrons within the reactor column can bring more than a factor 100 of cold
neutron flux incident on the superfluid helium with respect to the present cold
neutron beam conditions at the ILL reactor. The storage lifetime for UCN in
superfluid He at 1.2 K is about 30 s, which is sufficient when feeding
experiments requiring a similar filling time. The calculated density of UCN
with energy between 50 neV and 250 neV in an experimental volume of 40 liters
is about 10^4 n/cm^3. Technical solutions for realization of the project are
discussed.


title: Least Squares Methods for Equidistant Tree Reconstruction

abstract:
  UPGMA is a heuristic method identifying the least squares equidistant
phylogenetic tree given empirical distance data among $n$ taxa. We study this
classic algorithm using the geometry of the space of all equidistant trees with
$n$ leaves, also known as the Bergman complex of the graphical matroid for the
complete graph $K_n$. We show that UPGMA performs an orthogonal projection of
the data onto a maximal cell of the Bergman complex. We also show that the
equidistant tree with the least (Euclidean) distance from the data is obtained
from such an orthogonal projection, but not necessarily given by UPGMA. Using
this geometric information we give an extension of the UPGMA algorithm. We also
present a branch and bound method for finding the best equidistant tree.
Finally, we prove that there are distance data among $n$ taxa which project to
at least $(n-1)!$ equidistant trees.


title: Solar Coronal Structures and Stray Light in TRACE

abstract:
  Using the 2004 Venus transit of the Sun to constrain a semi-empirical
point-spread function for the TRACE EUV solar telescope, we have measured the
effect of stray light in that telescope. We find that 43% of 171A EUV light
that enters TRACE is scattered, either through diffraction off the entrance
filter grid or through other nonspecular effects. We carry this result forward,
via known-PSF deconvolution of TRACE images, to identify its effect on analysis
of TRACE data. Known-PSF deconvolution by this derived PSF greatly reduces the
effect of visible haze in the TRACE 171A images, enhances bright features, and
reveals that the smooth background component of the corona is considerably less
bright (and hence much more rarefied) than commonly supposed. Deconvolution
reveals that some prior conlclusions about the Sun appear to have been based on
stray light in the images. In particular, the diffuse background "quiet corona"
becomes consistent with hydrostatic support of the coronal plasma; feature
contrast is greatly increased, possibly affecting derived parameters such as
the form of the coronal heating function; and essentially all existing
differential emission measure studies of small features appear to be affected
by contamination from nearby features. We speculate on further implications of
stray light for interpretation of EUV images from TRACE and similar
instruments, and advocate deconvolution as a standard tool for image analysis
with future instruments such as SDO/AIA.


title:
Deformations of glassy polymers in very low temperature regime within
  cylindrical micropores

abstract:
  The deformation kinetics for glassy polymers confined in microscopic domain
at very low temperature regime was investigated using a transition-rate-state
dependent model considering the shear thinning behavior which means, once
material being subjected to high shear rates, the viscosity diminishes with
increasing shear rate. The preliminary results show that there might be nearly
frictionless fields for rate of deformation due to the almost vanishing shear
stress in micropores at very low temperature regime subjected to some surface
conditions : The relatively larger roughness (compared to the macroscopic
domain) inside micropores and the slip. As the pore size decreases, the
surface-to-volume ratio increases and therefore, surface roughness will greatly
affect the deformation kinetics in micropores.
  By using the boundary perturbation method, we obtained a class of temperature
and activation energy dependent fields for the deformation kinetics at low
temperature regime with the presumed small wavy roughness distributed along the
walls of an cylindrical micropore. The critical deformation kinetics of the
glassy matter is dependent upon the temperature, activation energy, activation
volume, orientation dependent and is proportional to the (referenced) shear
rate, the slip length, the amplitude and the orientation of the wavy-roughness.


title: Pretzelosity distribution function

abstract:
  The 'pretzelosity' distribution is discussed. Theoretical properties, model
results, and perspectives to access experimental information on this leading
twist, transverse momentum dependent parton distribution function are reviewed.
Its relation to helicity and transversity distributions is highlighted.


title:
Dark Bursts in the Swift Era: The Palomar 60 inch-Swift Early Optical
  Afterglow Catalog

abstract:
  We present multi-color optical observations of long-duration gamma-ray bursts
(GRBs) made over a three year period with the robotic Palomar 60 inch telescope
(P60). Our sample consists of all 29 events discovered by Swift for which P60
began observations less than one hour after the burst trigger. We were able to
recover 80% of the optical afterglows from this prompt sample, and we attribute
this high efficiency to our red coverage. Like Melandri et al. (2008), we find
that a significant fraction (~ 50%) of Swift events show a suppression of the
optical flux with regards to the X-ray emission (so-called "dark" bursts). Our
multi-color photometry demonstrates this is likely due in large part to
extinction in the host galaxy. We argue that previous studies, by selecting
only the brightest and best-sampled optical afterglows, have significantly
underestimated the amount of dust present in typical GRB environments.


title:
Empirical LCAO parameters for $\pi$ molecular orbitals in planar organic
  molecules

abstract:
  We present a parametrization within a simplified LCAO model (a type of
Hueckel model) for the description of $\pi$ molecular orbitals in organic
molecules containing $\pi$-bonds between carbon, nitrogen, or oxygen atoms with
$sp^2$ hybridization, which we show to be quite accurate in predicting the
energy of the highest occupied $\pi$ orbital and the first $\pi$-$\pi*$
transition energy for a large set of organic compounds. We provide four
empirical parameter values for the diagonal matrix elements of the LCAO
description, corresponding to atoms of carbon, nitrogen with one $p_z$
electron, nitrogen with two $p_z$ electrons, and oxygen. The bond-length
dependent formula (proportional to $1/d^2$) of Harrison is used for the
non-diagonal matrix elements between neighboring atoms. The predictions of our
calculations have been tested against available experimental results in more
than sixty organic molecules, including benzene and its derivatives,
polyacenes, aromatic hydrocarbons of various geometries, polyenes, ketones,
aldehydes, azabenzenes, nucleic acid bases and others. The comparison is rather
successful, taking into account the small number of parameters and the
simplicity of the LCAO method, involving only $p_z$ atomic orbitals, which
leads even to analytical calculations in some cases.


title:
X-ray and UV spectroscopy of Galactic diffuse hot gas along the LMC X--3
  sight line

abstract:
  We present Suzaku spectra of X-ray emission in the fields just off the LMC
X-3 sight line. OVII, OVIII, and NeIX emission lines are clearly detected,
suggesting the presence of an optically thin thermal plasma with an average
temperature of 2.4E6. This temperature is significantly higher than that
inferred from existing X-ray absorption line data obtained with Chandra grating
observations of LMC X-3, strongly suggesting that the gas is not isothermal. We
then jointly analyze these data to characterize the spatial and temperature
distributions of the gas. Assuming a vertical exponential Galactic disk model,
we estimate the gas temperature and density at the Galactic plane and their
scale heights as 3.6(2.9, 4.7)E6 K and 1.4(0.3, 3.4)E-3 cm^{-3} and 1.4(0.2,
5.2) kpc and $2.8(1.0, 6.4)$ kpc, respectively. This characterization can
account for all the \ovi line absorption, as observed in a FUSE spectrum of LMC
X-3, but only predicts less than one tenth of the OVI line emission intensity
typically detected at high Galactic latitudes. The bulk of the OVI emission
most likely arises at interfaces between cool and hot gases.


title:
Implications for C-14 Dating of the Jenkins-Fischbach Effect and
  Possible Fluctuation of the Solar Fusion Rate

abstract:
  It has long been known that the C-14 calibration curve, which relates the
known age of tree rings to their apparent C-14 ages, includes a number of
"wiggles" which clearly are not experimental errors or other random effects. A
reasonable interpretation of these wiggles is that they indicate that the Sun's
fusion "furnace" is pulsating, perhaps for reasons similar to that of the
Cepheid variables, albeit under a very different regime of pressure and
temperature. If this speculation is correct, we are seeing the heartbeat of the
Sun-the C-14 calibration curve is the Sun's "neutrino-cardiogram." Elevated
neutrino flux during a relatively brief period would have two effects: (1) a
surge in C-14 fraction in the atmosphere, which would make biological samples
that were alive during the surge appear to be "too young" (2) depletion of C-14
in the biotic matter already dead at the time of the surge; this is a
consequence of the recently discovered Jenkins-Fischbach effect, which is an
observed correlation between nuclear decay rates and solar activity or
Earth-Sun distance.
  In addition, the precise value at any given time of the "half-life" of any
unstable isotope-including C-14-must now be considered in doubt, since the
Jenkins-Fischbach effect implies that we may no longer view the decay rate of
an isotope as intrinsically governed and therefore a constant of Nature.


title: Atmospheric composition and structure of HD209458b

abstract:
  Transiting planets like HD209458b offer a unique opportunity to scrutinize
their atmospheric composition and structure. Transit spectroscopy probes the
transition region between the day and night sides, called limb. We present a
re-analysis of existing archived HST/STIS transmission spectra of HD209458b's
atmosphere. From these observations we: Identify H2 Rayleigh scattering, derive
the absolute Sodium abundance and quantify its depletion in the upper
atmosphere, extract a stratospheric T-P profile with a temperature inversion
and explain broad band absorptions with the presence of TiO and VO molecules in
the atmosphere of this planet.


title:
Spatial and Temporal Heterogeneity of Host-Parasitoid Interactions in
  Lupine Habitat

abstract:
  The inhabitants of the bush lupine in coastal California have been the
subject of scientific scrutiny in recent years. Observations of a
host-parasitoid interaction in the shrub's foliage, in which victims are
significantly less motile than their exploiters, record stable spatial patterns
in a fairly homogeneous environment. Though such pattern formation has been
found in reaction-diffusion models, the correspondence of these models to
continuous-time predator-prey interactions does not reflect the reality of the
system being studied. Near the root of the lupine, another host-parasitoid
interaction is also of considerable interest. In some cases this interaction,
which promotes the health of the lupine, has been observed to be much more
persistent than suggested by mathematical models.
  In this work a discrete-time spatial model of the first host-parasitoid
system is introduced. We analyze the model, describing its transient behavior
and finding the conditions under which spatial patterns occur, as well as an
estimate of outbreak size under those conditions. We consider the feasibility
of the necessary conditions in the natural system by modeling the mechanisms
responsible for them, and discuss the effects of variable habitat on pattern
formation. We also explore one possible explanation for the persistence of the
second host-parasitoid system -- the existence of an alternate host. Under
certain surprising conditions and by means quite different from previous models
of similar situations, an alternate host can greatly enhance persistence of the
nematode parasitoid.


title: Lagrangian Quantum Homology

abstract:
  The present paper is mainly a survey of our work arXiv:0708.4221 and
arXiv:0808.2440 but it also contains the announcement of some new results. Its
main purpose is to present an accessible introduction to a technique allowing
efficient calculations in Lagrangian Floer theory.


title: Adaptive Dynamic Congestion Avoidance with Master Equation

abstract:
  This paper proposes an adaptive variant of Random Early Detection (RED)
gateway queue management for packet-switched networks via a discrete state
analog of the non-stationary Master Equation i.e. Markov process. The
computation of average queue size, which appeared in the original RED
algorithm, is altered by introducing a probability $P(l,t)$, which defines the
probability of having $l$ number of packets in the queue at the given time $t$,
and depends upon the previous state of the queue. This brings the advantage of
eliminating a free parameter: queue weight, completely. Computation of
transition rates and probabilities are carried out on the fly, and determined
by the algorithm automatically. Simulations with unstructured packets
illustrate the method, the performance of the adaptive variant of RED
algorithm, and the comparison with the standard RED.


title: Photoproduction in Ultra-Peripheral Heavy Ion Collisions at STAR

abstract:
  We present recent STAR results on photoproduction in ultra-peripheral
relativistic heavy ion collisions. In these collisions the impact parameter of
the beam particles is larger than the sum of their nuclear radii, so that they
interact via their long-range Coulomb fields. STAR has measured the production
of $\rho^0(770)$ mesons in exclusive reactions as well as in processes with
mutual nuclear excitation of the beam particles. We present results for the
$\rho^0$ production cross section in Au-Au collisions at $\sqrt{s_{NN}}=200$
GeV for coherent as well as incoherent coupling. The dependence of the cross
section on the $\rho^0$ rapidity is compared to theoretical models. We also
studied the ratio of coherent $\rho^0$ to direct $\pi^+\pi^-$ production as
well as the $\rho^0$ helicity matrix elements and we observe interference
effects in the $\rho^0$ production. In addition STAR has measured the
production of $\rho^0$ mesons in d-Au collisions at $\sqrt{s_{NN}}=200$ GeV and
that of $e^+e^-$-pairs in Au-Au at $\sqrt{s_{NN}}=200$ GeV. We also see an
enhancement around 1510 MeV/c in $\pi^+\pi^-\pi^+\pi^-$ final states in Au-Au
collisions at $\sqrt{s_{NN}}=200$ GeV.


title:
Modeling Stellar Atmospheres with a Spherically Symmetric Version of the
  Atlas Code: Testing the Code by Comparisons to Interferometric Observations
  and PHOENIX Models

abstract:
  One of the current opportunities for stellar atmospheric modeling is the
interpretation of optical interferometric data of stars. Starting from the
robust, open source ATLAS atmospheric code (Kurucz, 1979), we have developed a
spherically symmetric code, SATLAS, as a new option for modeling stellar
atmospheres of low gravity stars. The SATLAS code is tested against both
interferometric observations of M giants by Wittkowski and collaborators, and
spherically symmetric M giant NextGen models from the PHOENIX code. The SATLAS
models predict interferometric visibilities that agree with the observed
visibilities and with predicted visibilities, and the SATLAS atmospheric
structures also agree with those from spherical PHOENIX models, with just small
differences in temperature and pressure at large depths in the atmospheres.


title: On the Stability of Electrostatic Orbits

abstract:
  We analyze the stability of two charged conducting spheres orbiting each
other. Due to charge polarization, the electrostatic force between the two
spheres deviates significantly from $1/r^2$ as they come close to each other.
As a consequence, there exists a critical angular momentum, $L_c$, with a
corresponding critical radius $r_c$. For $L > L_c$ two circular orbits are
possible: one at $r > r_c$ that is stable and the other at $r < r_c$ that is
unstable. This critical behavior is analyzed as a function of the charge and
the size ratios of the two spheres.


title: Changes in Dark Matter Properties After Freeze-Out

abstract:
  The properties of the dark matter that determine its thermal relic abundance
can be very different from the dark matter properties today. We investigate
this possibility by coupling a dark matter sector to a scalar that undergoes a
phase transition after the dark matter freezes out. If the value of Omega_DM
h^2 calculated from parameters measured at colliders and by direct and indirect
detection experiments does not match the astrophysically observed value, a
novel cosmology of this type could provide the explanation. This mechanism also
has the potential to account for the "boost factor" required to explain the
PAMELA data.


title:
Modeling Mass-Loss and Infrared Excess in Large Magellanic Cloud
  Cepheids

abstract:
  The purpose of this preliminary work is to determine if Large Magellanic
Cloud (LMC) Cepheids have stellar winds. If a Cepheid undergoes mass loss then
at some distance from the star, a fraction of the gas becomes dust, which
causes an infrared excess. Mass loss is tested using OGLE II optical
observations and SAGE infrared observations for a sample of 488 Cepheids. The
resultant mass-loss rates range from $10^{-12}$ to $10^{-7}$ $M_\odot/yr$.
Using the mass--loss model we compute infrared stellar luminosities for the
sample of Cepheids and compare predicted infrared PL relations with observed
relations. The predicted relations not only vary from the observed relations,
implying mass loss plays a significant role, but also show evidence for
non-linearity. It is determined that mass loss is important for LMC Cepheids.


title: Dynamical and Statistical Criticality in a Model of Neural Tissue

abstract:
  For the nervous system to work at all, a delicate balance of excitation and
inhibition must be achieved. However, when such a balance is sought by global
strategies, only few modes remain balanced close to instability, and all other
modes are strongly stable. Here we present a simple model of neural tissue in
which this balance is sought locally by neurons following `anti-Hebbian'
behavior: {\sl all} degrees of freedom achieve a close balance of excitation
and inhibition and become "critical" in the dynamical sense. At long
timescales, the modes of our model oscillate around the instability line, so an
extremely complex "breakout" dynamics ensues in which different modes of the
system oscillate between prominence and extinction. We show the system develops
various anomalous statistical behaviours and hence becomes self-organized
critical in the statistical sense.


title:
Viability for stochastic differential equations driven by fractional
  Brownian motion

abstract:
  In this paper we prove a viability result for multidimensional, time
dependent, stochastic differential equations driven by fractional Brownian
motion with Hurst parameter1/2 < H < 1, using pathwise approach. The sufficient
condition is also an alternative global existence result for the fractional
differential equations with restrictions on the state.


title: Emergence of a Quasar Outflow

abstract:
  We report the first discovery of the emergence of a high-velocity broad-line
outflow in a luminous quasar, J105400.40+034801.2 at redshift z ~ 2.1. The
outflow is evident in ultraviolet CIV and SiIV absorption lines with velocity
shifts v ~ 26,300 km/s and deblended widths FWHM ~ 4000 km/s. These features
are marginally strong and broad enough to be considered broad absorption lines
(BALs), but their large velocities exclude them from the standard BAL
definition. The outflow lines appeared between two observations in the years
2002.18 and 2006.96. A third observation in 2008.48 showed the lines becoming
~40% weaker and 10% to 15% narrower. There is no evidence for acceleration or
for any outflow gas at velocities <23,000 km/s. The lines appear to be
optically thick, with the absorber covering just 20% of the quasar continuum
source. This indicates a characteristic absorber size of ~4 x 10^15 cm, but
with a BAL-like total column density log N_H (cm^-2) > 21.2 and average space
density n_H > 2 x 10^5 cm^-3. We attribute the emergence of the outflow lines
to a substantial flow structure moving across our line of sight, possibly near
the ragged edge of the main BAL flow or possibly related to the onset of a BAL
evolutionary phase.


title: Alpha Channeling in a Rotating Plasma

abstract:
  The wave-particle alpha-channeling effect is generalized to include rotating
plasma. Specifically, radio frequency waves can resonate with alpha particles
in a mirror machine with ExB rotation to diffuse the alpha particles along
constrained paths in phase space. Of major interest is that the alpha-particle
energy, in addition to amplifying the RF waves, can directly enhance the
rotation energy which in turn provides additional plasma confinement in
centrifugal fusion reactors. An ancillary benefit is the rapid removal of alpha
particles, which increases the fusion reactivity.


title:
Precision and Casimir Force Measurements in Superfluid and Vacuum with
  Silicon Nitride Membranes

abstract:
  The recent discovery that silicon nitride membranes can be used as extremely
high Q mechanical resonators makes possible a number of novel experiments,
which include improved long range vacuum Casimir force measurements, and
measurments of the properties of liquid helium below the lambda point. It is
noted that in the thermal correction to the Casimir force, the phase velocity
of the excitations does not enter, with the force per unit area between
parallel plates depending only on the temperature and distance between the
plates. Thus it appears as possible to measure the phonon analog of the finite
temperature Casimir force in liquid helium.


title:
A Stellar Dynamical Measurement of the Black Hole Mass in the Maser
  Galaxy NGC 4258

abstract:
  We determine the mass of the black hole at the center of the spiral galaxy
NGC 4258 by constructing axisymmetric dynamical models of the galaxy. These
models are constrained by high spatial resolution imaging and long-slit
spectroscopy of the nuclear region obtained with the {\em Hubble Space
Telescope}, complemented by ground-based observations extending to larger
radii. Our best mass estimate is $\MBH = (3.3 \pm 0.2) \times 10^7 \MSun $ for
a distance of 7.28 Mpc (statistical errors only). This is within 15% of $
(3.82\pm 0.01) \times 10^7 \MSun$, the mass determined from the kinematics of
water masers (rescaled to the same distance) assuming they are in Keplerian
rotation in a warped disk. The construction of accurate dynamical models of NGC
4258 is somewhat compromised by an unresolved active nucleus and color
gradients, the latter caused by variations in the stellar population and/or
obscuring dust. These problems are not present in the $\sim 30$ other black
hole mass determinations from stellar dynamics that have been published by us
and other groups; thus, the relatively close agreement between the stellar
dynamical mass and the maser mass in NGC 4258 enhances our confidence in the
black hole masses determined in other galaxies from stellar dynamics using
similar methods and data of comparable quality.


title:
Gravitational-Wave Extraction from Neutron Star Oscillations: comparing
  linear and nonlinear techniques

abstract:
  The main aim of this study is the comparison of gravitational waveforms
obtained from numerical simulations which employ different numerical evolution
approaches and different wave-extraction techniques. For this purpose, we
evolve an oscillating, non-rotating polytropic neutron-star model with two
different approaches: a full nonlinear relativistic simulation (in three
dimensions) and a linear simulation based on perturbation theory. The
extraction of the gravitational-wave signal is performed with three methods:
The gauge-invariant curvature-perturbation theory based on the Newman-Penrose
scalar $\psi_4$; The gauge-invariant Regge-Wheeler-Zerilli-Moncrief
metric-perturbation theory of a Schwarzschild space-time; Some generalization
of the quadrupole emission formula.


title:
Counting Solutions for the N-queens and Latin Square Problems by
  Efficient Monte Carlo Simulations

abstract:
  We apply Monte Carlo simulations to count the numbers of solutions of two
well-known combinatorial problems: the N-queens problem and Latin square
problem. The original system is first converted to a general thermodynamic
system, from which the number of solutions of the original system is obtained
by using the method of computing the partition function. Collective moves are
used to further accelerate sampling: swap moves are used in the N-queens
problem and a cluster algorithm is developed for the Latin squares. The method
can handle systems of $10^4$ degrees of freedom with more than $10^10000$
solutions. We also observe a distinct finite size effect of the Latin square
system: its heat capacity gradually develops a second maximum as the size
increases.


title:
Measuring the undetectable: Proper motions and parallaxes of very faint
  sources

abstract:
  The near future of astrophysics involves many large solid-angle, multi-epoch,
multi-band imaging surveys. These surveys will, at their faint limits, have
data on large numbers of sources that are too faint to be detected at any
individual epoch. Here we show that it is possible to measure in multi-epoch
data not only the fluxes and positions, but also the parallaxes and proper
motions of sources that are too faint to be detected at any individual epoch.
The method involves fitting a model of a moving point source simultaneously to
all imaging, taking account of the noise and point-spread function in each
image. By this method it is possible to measure the proper motion of a point
source with an uncertainty close to the minimum possible uncertainty given the
information in the data, which is limited by the point-spread function, the
distribution of observation times (epochs), and the total signal-to-noise in
the combined data. We demonstrate our technique on multi-epoch Sloan Digital
Sky Survey imaging of the SDSS Southern Stripe. We show that we can distinguish
very red brown dwarfs by their proper motions from very high-redshift quasars
more than $1.6\mag$ fainter than with traditional technique on these SDSS data,
and with better better fidelity than by multi-band imaging alone. We
re-discover all 10 known brown dwarfs in our sample and present 9 new candidate
brown dwarfs, identified on the basis of high proper motion.


title: The Scalar Curvature Equation on $S^3$

abstract:
  We give existence results for solutions of the prescribed scalar curvature
equation on $S^3$, when the curvature function is a positive Morse function and
satisfies an index-count condition.


title:
Non-thermal emission from supernova shock breakout and the origin of the
  X-ray transient associated with SN2008D

abstract:
  We suggest that non-thermal emission can be produced by multiple scatterings
of the photons between the supernova ejecta and pre-shock material in supernova
shock breakout. Such bulk-Comptonization process may significantly change the
original thermal photon spectrum, forming a power-law non-thermal component at
higher energies. We then show that the luminous X-ray outburst XRO081009
associated with SN2008D is likely to be such shock breakout emission from an
ordinary type Ib/c supernova.


title:
All-Inorganic Spin-Cast Nanoparticle Solar Cells with Non-Selective
  Electrodes

abstract:
  Spin-cast all-inorganic nanoparticle solutions have been used to make a
CdTe/CdSe solar cell with an efficiency of up to 2.8% without alumina or
calcium buffer layers. The type of junction and non-selective nature of the
contacts made to these devices is explored.