title: Anisotropic turbulent model for solar coronal heating

abstract:
  Context : We present a self-consistent model of solar coronal heating,
originally developed by Heyvaert & Priest (1992), in which we include the
dynamical effect of the background magnetic field along a coronal structure by
using exact results from wave MHD turbulence (Galtier et al. 2000). Aims : We
evaluate the heating rate and the microturbulent velocity for comparison with
observations in the quiet corona, active regions and also coronal holes.
Methods :The coronal structures are assumed to be in a turbulent state
maintained by the slow erratic motions of the magnetic footpoints. A
description for the large-scale and the unresolved small-scale dynamics are
given separately. From the latter, we compute exactly (or numerically for
coronal holes) turbulent viscosites that are finally used in the former to
close self-consistently the system and derive the heating flux expression.
Results : We show that the heating rate and the turbulent velocity compare
favorably with coronal observations. Conclusions : Although the Alfven wave
turbulence regime is strongly anisotropic, and could reduce a priori the
heating efficiency, it provides an unexpected satisfactory model of coronal
heating for both magnetic loops and open magnetic field lines.


title: Green function for a two-dimensional discrete Laplace-Beltrami operator

abstract:
  We study a discrete model of the Laplacian in $\mathbb{R}^2$ that preserves
the geometric structure of the original continual object. This means that,
speaking of a discrete model, we do not mean just the direct replacement of
differential operators by difference ones but also a discrete analog of the
Riemannian structure. We consider this structure on the appropriate
combinatorial analog of differential forms. Self-adjointness and boundness for
a discrete Laplacian are proved. We define the Green function for this operator
and also derive an explicit formula of the one.


title: Large tensor-to-scalar ratio and low scale inflation

abstract:
  It is plausible that the scalar density perturbations are created by a
relatively low scale model of inflation which predicts the CMB anisotropy and
excites Standard Model baryon and cold dark matter, but negligible gravity
waves. Nevertheless a significantly large tensor perturbations can be observed
if there exists a prior phase of high scale inflation separated by a matter or
radiation dominated epoch. In this paper we provide a simple example when the
gravity waves generated at high scales trickle through the horizon of the
second phase of inflation and leave a distinct imprint in the spectrum of the
tensor modes. For a high scale inflation occurring at $H\sim 10^{13}$ GeV while
the second phase of inflation happening at $H\sim 1$ GeV, the largest tensor to
scalar ratio is bounded by $r_{\rm observed}\leq0.8$.


title:
Comment on `On the next-to-leading order gravitational spin(1)-spin(2)
  dynamics' by J. Steinhoff et al

abstract:
  In this comment we explain the discrepancy found between the results in
arXiv:0712.1716v1 for the 3PN spin-spin potential and those previously derived
in gr-qc/0604099. We point out that to compare one must include sub-leading
lower order spin-orbit effects which contribute to the spin-spin potential once
one transforms to the PN frame. When these effects are included the results in
arXiv:0712.1716v1 do indeed reproduce those found in gr-qc/0604099.


title:
Where to place a spherical obstacle so as to maximize the second
  Dirichlet eigenvalue

abstract:
  We prove that among all doubly connected domains of $\mathbb{R}^n$ bounded by
two spheres of given radii, the second eigenvalue of the Dirichlet Laplacian
achieves its maximum when the spheres are concentric (spherical shell). The
corresponding result for the first eigenvalue has been established by Hersch in
dimension 2, and by Harrell, Kr\"oger and Kurata and Kesavan in any dimension.
We also prove that the same result remains valid when the ambient space
$\mathbb{R}^n$ is replaced by the standard sphere $\mathbb{S}^n$ or the
hyperbolic space $\mathbb{H}^n$ .


title: Exploring proteins multi-funnel energy landscape

abstract:
  An all-atom model of proteins is used to show that the same sequence of amino
acids can have many alternative structures, that are very distant from, and
that can be as stable as, the corresponding native structure. Such alternative
structures are not easily rationalized as belonging to the native basin and
indicate instead that the free energy landscape of proteins is
multi-funnel-shaped and that Anfinsen's thermodynamic hypothesis alone cannot
explain protein folding. An alternative two-step process for folding is
proposed and its consistency with the experimental evidence available is
discussed.


title: Some new results on one-dimensional outflow dynamics

abstract:
  In this paper we introduce modified version of one-dimensional outflow
dynamics (known as a Sznajd model) which simplifies the analytical treatment.
We show that simulations results of the original and modified rules are exactly
the same for various initial conditions. We obtain the analytical formula for
exit probability using Kirkwood approximation and we show that it agrees
perfectly with computer simulations in case of random initial conditions.
Moreover, we compare our results with earlier analytical calculations obtained
from renormalization group and from general sequential probabilistic frame
introduced by Galam. Using computer simulations we investigate the time
evolution of several correlation functions to show if Kirkwood approximation
can be justified. Surprisingly, it occurs that Kirkwood approximation gives
correct results even for these initial conditions for which it cannot be easily
justified.


title:
Lower bound on the four-point dynamical susceptibility: Direct
  experimental test on a granular packing

abstract:
  We track the motion of a horizontally vibrated amorphous assembly of
bidisperse hard disks, for densities ranging across the jamming transition. We
derive on very general grounds a bound on the dynamical susceptibility in terms
of the response of the dynamics to a change in density. This generalizes a
similar bound recently derived for equilibrium liquids. We find that in our
experimental system the bound is tight and reproduces the non-monotonic
behavior of the dynamical susceptibility both in time and density across the
jamming transition. The underlying scaling behavior reveals an intimate
connection between anomalous diffusion and dynamical heterogeneity.


title:
The logarithmic perturbation theory for bound states in
  spherical-symmetric potentials via the $\hbar$-expansions

abstract:
  The explicit semiclassical treatment of the logarithmic perturbation theory
for the bound-state problem for the spherical anharmonic oscillator and the
screened Coulomb potential is developed. Based upon the $\hbar$-expansions and
suitable quantization conditions a new procedure for deriving perturbation
expansions is offered. Avoiding disadvantages of the standard approach, new
handy recursion formulae with the same simple form both for ground and excited
states have been obtained. As examples, the perturbation expansions for the
energy eigenvalues of the quartic anharmonic oscillator and the Debye potential
are considered.


title: Jet Physics at CDF

abstract:
  Recent results on jet physics at the Fermilab Tevatron $p\bar p$ collider
from the CDF Collaboration are presented. The main focus is put on results for
the inclusive jet and dijet, $b\bar b$ dijet, $W/Z+$jets and $W/Z+b$-jets
production.


title: Flavor in Supersymmetry with an Extended R-symmetry

abstract:
  We propose a new solution to the supersymmetric flavor problem without
flavor-blind mediation. Our proposal is to enforce a continuous or a suitably
large discrete R-symmetry on weak scale supersymmetry, so that Majorana gaugino
masses, trilinear A-terms, and the mu-term are forbidden. We find that
replacing the MSSM with an R-symmetric supersymmetric model allows order one
flavor-violating soft masses, even for squarks of order a few hundred GeV. The
minimal R-symmetric supersymmetric model contains Dirac gaugino masses and
R-symmetric Higgsino masses with no left-right mixing in the squark or slepton
sector. Dirac gaugino masses of order a few TeV with vanishing A-terms solve
most flavor problems, while the R-symmetric Higgs sector becomes important at
large tan(beta). epsilon_K can be accommodated if CP is preserved in the SUSY
breaking sector, or if there is a moderate flavor degeneracy, which can arise
naturally. epsilon'/epsilon, as well as neutron and electron EDMs are easily
within experimental bounds. The most striking phenomenological distinction of
this model is the order one flavor violation in the squark and slepton sector,
while the Dirac gaugino masses tend to be significantly heavier than the
corresponding squark and slepton masses.


title: The New Ekpyrotic Ghost

abstract:
  The new ekpyrotic scenario attempts to solve the singularity problem by
involving violation of the null energy condition in a model which combines the
ekpyrotic/cyclic scenario with the ghost condensate theory and the curvaton
mechanism of production of adiabatic perturbations of metric. The Lagrangian of
this theory, as well as of the ghost condensate model, contains a term with
higher derivatives, which was added to the theory to stabilize its vacuum
state. We found that this term may affect the dynamics of the cosmological
evolution. Moreover, after a proper quantization, this term results in the
existence of a new ghost field with negative energy, which leads to a
catastrophic vacuum instability. We explain why one cannot treat this dangerous
term as a correction valid only at small energies and momenta below some UV
cut-off, and demonstrate the problems arising when one attempts to construct a
UV completion of this theory.


title: Phenomenology of Hidden Valleys at Hadron Colliders

abstract:
  We study the phenomenology of, and search techniques for, a class of "Hidden
Valleys." These models are characterized by low mass (well below a TeV) bound
states resulting from a confining gauge interaction in a hidden sector; the
states include a spin-one resonance that can decay to lepton pairs. Assuming
that the hidden sector communicates to the Standard Model (SM) through TeV
suppressed operators, taking into account the constraint from the $Z$ pole
physics at LEP, searches at Tevatron may be difficult in the particular class
of Hidden Valleys we consider, so that we concentrate on the searches at the
LHC. Hidden Valley events are characterized by high multiplicities of jets and
leptons in the final state. Depending on the scale of confinement in the hidden
sector, the events are typically more spherical, with lower thrust and higher
incidences of isolated leptons, than those from the SM background processes.
Most notably, high cluster invariant mass and very narrow, low mass resonances
in lepton pairs are the key observables to identify the signal. We use these
characteristics to develop a set of cuts to separate the Hidden Valley from SM,
and show that with these cuts LHC has a significant reach in the parameter
space. Our strategies are quite general and should apply well beyond the
particular class of models studied here.


title:
Do broad absorption line quasars live in different environments from
  ordinary quasars?

abstract:
  We select a sample of $\sim 4200$ traditionally defined broad absorption line
quasars (BALQs) from the Fifth Data Release quasar catalog of the Sloan Digital
Sky Survey. For a statistically homogeneous quasar sample with $1.7\le z\le
4.2$, the BAL quasar fraction is $\sim 14%$ and is almost constant with
redshift. We measure the auto-correlation of non-BAL quasars (nonBALQs) and the
cross-correlation of BALQs with nonBALQs using this statistically homogeneous
sample, both in redshift space and using the projected correlation function. We
find no significant difference between the clustering strengths of BALQs and
nonBALQs. Assuming a power-law model for the real space correlation function
$\xi(r)=(r/r_0)^{-1.8}$, the correlation length for nonBALQs is $r_0=7.6\pm 0.8
h^{-1}{\rm Mpc}$; for BALQs, the cross-correlation length is $r_0=7.4\pm 1.1
h^{-1}{\rm Mpc}$. Our clustering results suggest that BALQs live in similar
large-scale environments as do nonBALQs.


title:
Quantum modes in DBI inflation: exact solutions and constraints from
  vacuum selection

abstract:
  We study a two-parameter family of exactly solvable inflation models with
variable sound speed, and derive a corresponding exact expression for the
spectrum of curvature perturbations. We generalize this expression to the slow
roll case, and derive an approximate expression for the scalar spectral index
valid to second order in slow roll. We apply the result to the case of DBI
inflation, and show that for certain choices of slow roll parameters, the
Bunch-Davies limit (a) does not exist, or (b) is sensitive to stringy physics
in the bulk, which in principle can have observable signatures in the
primordial power spectrum.


title:
Multiplicity Fluctuations in Nucleus-Nucleus Collisions: Dependence on
  Energy and Atomic Number

abstract:
  Event-by-event multiplicity fluctuations in central C+C, S+S, In+In, and
Pb+Pb as well as p+p collisions at bombarding energies from 10 to 160 AGeV are
studied within the HSD and UrQMD microscopic transport approaches. Our
investigation is directly related to the future experimental program of the
NA61 Collaboration at the SPS for a search of the QCD critical point. The
dependence on energy and atomic mass number of the scaled variances for
negative, positive, and all charged hadrons is presented and compared to the
results of the model of independent sources. Furthermore, the nucleus-nucleus
results from the transport calculations are compared to inelastic proton-proton
collisions for reference. We find a dominant role of the participant number
fluctuations in nucleus-nucleus reactions at finite impact parameter $b$. In
order to reduce the influence of the participant numbers fluctuations on the
charged particle multiplicity fluctuations only the most central events have to
be selected. Accordingly, the samples of the 1% most central nucleus-nucleus
collisions with the largest numbers of the projectile participants are studied.
The results are compared with those for collisions at zero impact parameter. A
strong influence of the centrality selection criteria on the multiplicity
fluctuations is pointed out. Our findings are essential for an optimal choice
of colliding nuclei and bombarding energies for the experimental search of the
QCD critical point.


title: Quantum Criticality in Heavy Fermion Metals

abstract:
  Quantum criticality describes the collective fluctuations of matter
undergoing a second-order phase transition at zero temperature. Heavy fermion
metals have in recent years emerged as prototypical systems to study quantum
critical points. There have been considerable efforts, both experimental and
theoretical, which use these magnetic systems to address problems that are
central to the broad understanding of strongly correlated quantum matter. Here,
we summarize some of the basic issues, including i) the extent to which the
quantum criticality in heavy fermion metals goes beyond the standard theory of
order-parameter fluctuations, ii) the nature of the Kondo effect in the quantum
critical regime, iii) the non-Fermi liquid phenomena that accompany quantum
criticality, and iv) the interplay between quantum criticality and
unconventional superconductivity.


title: Diviseur Theta et Formes Differentielles

abstract:
  In this papers, we study the geometric and arithmetic properties of the theta
divisor associated to the sheaf of locally exact differential forms over a
curve in positive characteristic. In this published version, we prove a
stronger version of the main result of chapiter 5.


title:
A geometric theory of swimming: Purcell's swimmer and its symmetrized
  cousin

abstract:
  We develop a qualitative geometric approach to swimming at low Reynolds
number which avoids solving differential equations and uses instead landscape
figures of two notions of curvatures: The swimming curvature and the curvature
derived from dissipation. This approach gives complete information for swimmers
that swim on a line without rotations and gives the main qualitative features
for general swimmers that can also rotate. We illustrate this approach for a
symmetric version of Purcell's swimmer which we solve by elementary analytical
means within slender body theory. We then apply the theory to derive the basic
qualitative properties of Purcell's swimmer.


title:
Correspondence Between the Phase Diagrams of TIP5P Water and a
  Spherically Symmetric Repulsive Ramp Potential

abstract:
  We perform molecular dynamics simulations of a well-known water model (the
TIP5P pair potential) and a simple liquid model (a two-scale repulsive ramp
potential) to compare the regions of anomalous behavior in their phase
diagrams. We select the parameters of the ramp potential by mapping it to an
effective pair potential derived from the TIP5P model. We find that the regions
of anomalous behavior in the phase diagrams of both systems can be mapped onto
each other if (i) pressure $P$ and temperature $T$ are replaced by $T-T_{C}$
and $P-P_{C}$, respectively, where $(T_{C},P_{C})$ are the coordinates of the
liquid-liquid critical point of the corresponding system; and (ii) a single
ramp particle corresponds to two TIP5P molecules. We present heuristic
arguments supporting point (ii). We also argue that the water-like anomalies in
the ramp potential are due to the ability of the particles to reproduce, upon
compression or heating, the migration of water molecules from the second shell
to its first shell.


title: Moving codimension-one subvarieties over finite fields

abstract:
  We give the first examples of nef line bundles on smooth projective varieties
over finite fields which are not semi-ample. More concretely, we find smooth
curves on smooth projective surfaces over finite fields such that the normal
bundle has degree zero, but no positive multiple of the curve moves in a family
of disjoint curves. This answers questions by Keel and Mumford.
  The proof uses an obstruction theory, in the spirit of homotopy theory, which
links the infinitely many obstructions to moving higher and higher multiples of
a given codimension-one subvariety.
  On 3-folds over a finite field, we find nef and big line bundles which are
not semi-ample. Finally, we reprove some of the known positive results about
semi-ampleness over finite fields.


title:
Search of S3 LIGO data for gravitational wave signals from spinning
  black hole and neutron star binary inspirals

abstract:
  We report on the methods and results of the first dedicated search for
gravitational waves emitted during the inspiral of compact binaries with
spinning component bodies. We analyze 788 hours of data collected during the
third science run (S3) of the LIGO detectors. We searched for binary systems
using a detection template family designed specially to capture the effects of
the spin-induced precession of the orbital plane. We present details of the
techniques developed to enable this search for spin-modulated gravitational
waves, highlighting the differences between this and other recent searches for
binaries with non-spinning components. The template bank we employed was found
to yield high matches with our spin-modulated target waveform for binaries with
masses in the asymmetric range 1.0 Msol < m1 < 3.0 Msol and 12.0 Msol < m2 <
20.0 Msol which is where we would expect the spin of the binary's components to
have significant effect. We find that our search of S3 LIGO data had good
sensitivity to binaries in the Milky Way and to a small fraction of binaries in
M31 and M33 with masses in the range 1.0 Msol < m1, m2 < 20.0 Msol. No
gravitational wave signals were identified during this search. Assuming a
binary population with spinning components and Gaussian distribution of masses
representing a prototypical neutron star - black hole system with m1 ~ 1.35
Msol and m2 ~ 5 Msol, we calculate the 90%-confidence upper limit on the rate
of coalescence of these systems to be 15.9 yr^-1 L_10^-1, where L_10 is 10^10
times the blue light luminosity of the Sun.


title:
Dirac-Sobolev inequalities and estimates for the zero modes of massless
  Dirac operators

abstract:
  The paper analyses the decay of any zero modes that might exist for a
massless Dirac operator $H:= \ba \cdot (1/i) \bgrad + Q, $ where $Q$ is $4
\times 4$-matrix-valued and of order $O(|\x|^{-1})$ at infinity. The approach
is based on inversion with respect to the unit sphere in $\R^3$ and
establishing embedding theorems for Dirac-Sobolev spaces of spinors $f$ which
are such that $f$ and $Hf$ lie in $(L^p(\R^3))^4, 1\le p<\infty.$


title:
Isogenies of supersingular elliptic curves over finite fields and
  operations in elliptic cohomology

abstract:
  We investigate stable operations in supersingular elliptic cohomology using
isogenies of supersingular elliptic curves over finite fields. Our main results
provide a framework in which we give a conceptually simple proof of an elliptic
cohomology version of the Morava change of rings theorem and also gives models
for explicit stable operations in terms of isogenies and morphisms in certain
enlarged isogeny categories. We relate our work to that of G. Robert on the
Hecke algebra structure of the ring of supersingular modular forms.


title: Equations of the moduli of Higgs pairs and infinite Grassmannian

abstract:
  In this paper the moduli space of Higgs pairs over a fixed smooth projective
curve with extra formal data is defined and it is endowed with a scheme
structure. We introduce a relative version of the Krichever map using a
fibration of Sato Grassmannians and show that this map is injective. This fact
and the characterization of the points of the image of the Krichever map allow
us to prove that this moduli space is a closed subscheme of the product of the
moduli of vector bundles (with formal extra data) and a formal anologue of the
Hitchin base. This characterization also provide us the method to compute
explicitely KP-type equations which describe the moduli space of Higgs pairs.
Finally, for the case where the spectral cover is totally ramified at a fixed
point of the curve, these equations are given in terms of the characteristic
coefficients of the Higgs field.


title:
Distributed Fair Scheduling Using Variable Transmission Lengths in
  Carrier-Sensing-based Wireless Networks

abstract:
  The fairness of IEEE 802.11 wireless networks (including Wireless LAN and
Ad-hoc networks) is hard to predict and control because of the randomness and
complexity of the MAC contentions and dynamics. Moreover, asymmetric channel
conditions such as those caused by capture and channel errors often lead to
severe unfairness among stations. In this paper we propose a novel distributed
scheduling algorithm that we call VLS, for ``{\em variable-length
scheduling}'', that provides weighted fairness to all stations despite the
imperfections of the MAC layer and physical channels. Distinct features of VLS
include the use of variable transmission lengths based on distributed
observations, compatibility with 802.11's contention window algorithm,
opportunistic scheduling to achieve high throughput in time-varying wireless
environments, and flexibility and ease of implementation. Also, VLS makes the
throughput of each station more smooth, which is appealing to real-time
applications such as video and voice. Although the paper mostly assumes 802.11
protocol, the idea generally applies to wireless networks based on CSMA
(Carrier Sensing Multiple Access).


title: One-Loop Renormalization of QCD with Lorentz Violation

abstract:
  The explicit one-loop renormalizability of the gluon sector of QCD with
Lorentz violation is demonstrated. The result is consistent with multiplicative
renormalization as the required counter terms are consistent with a single
re-scaling of the Lorentz-violation parameters. In addition, the resulting beta
functions indicate that the CPT-even Lorentz-violating terms increase with
energy scale in opposition to the asymptotically free gauge coupling and
CPT-odd terms. The calculations are performed at lowest-order in the
Lorentz-violating terms as they are assumed small.


title:
Nanoscale grains, high irreversibility field, and large critical current
  density as a function of high energy ball milling time in C-doped magnesium
  diboride

abstract:
  Magnesium diboride (MgB2) powder was mechanically alloyed by high energy ball
milling with C to a composition of Mg(B0.95C0.05)2 and then sintered at 1000 C
in a hot isostatic press. Milling times varied from 1 minute to 3000 minutes.
Full C incorporation required only 30-60 min of milling. Grain size of sintered
samples decreased with increased milling time to less than 30 nm for 20-50 hrs
of milling. Milling had a weak detrimental effect on connectivity. Strong
irreversibility field (H*) increase (from 13.3 T to 17.2 T at 4.2 K) due to
increased milling time was observed and correlated linearly with inverse grain
size (1/d). As a result, high field Jc benefited greatly from lengthy powder
milling. Jc(8 T, 4.2 K) peaked at > 80,000 A/cm2 with 1200 min of milling
compared with only ~ 26,000 A/cm2 for 60 min of milling. This non-compositional
performance increase is attributed to grain refinement of the unsintered powder
by milling, and to the probable suppression of grain growth by milling-induced
MgO nano-dispersions.


title:
Theoretical analysis of a single and double reflection atom
  interferometer in a weakly-confining magnetic trap

abstract:
  The operation of a BEC based atom interferometer, where the atoms are held in
a weakly-confining magnetic trap and manipulated with counter-propagating laser
beams, is analyzed. A simple analytic model is developed to describe the
dynamics of the interferometer. It is used to find the regions of parameter
space with high and low contrast of the interference fringes for both single
and double reflection interferometers. We demonstrate that for a double
reflection interferometer the coherence time can be increased by shifting the
recombination time. The theory is compared with recent experimental
realizations of these interferometers.


title: A Not-so-Characteristic Equation: the Art of Linear Algebra

abstract:
  Can the cross product be generalized? Why are the trace and determinant so
important in matrix theory? What do all the coefficients of the characteristic
polynomial represent? This paper describes a technique for `doodling' equations
from linear algebra that offers elegant solutions to all these questions. The
doodles, known as trace diagrams, are graphs labeled by matrices which have a
correspondence to multilinear functions. This correspondence permits
computations in linear algebra to be performed using diagrams. The result is an
elegant theory from which standard constructions of linear algebra such as the
determinant, the trace, the adjugate matrix, Cramer's rule, and the
characteristic polynomial arise naturally. Using the diagrams, it is easy to
see how little structure gives rise to these various results, as they all can
be `traced' back to the definition of the determinant and inner product.


title: Suppression of Tunneling in a Superconducting Persistent-Current Qubit

abstract:
  We consider a superconducting persistent-current qubit consisting of a
three-junction superconducting loop in an applied magnetic field. We show that
by choosing the field, Josephson couplings, and offset charges suitably, we can
perfectly suppress the tunneling between two oppositely directed states of
circulating current, leading to a vanishing of the splitting between the two
qubit states. The suppression arises for interference between tunneling along
different paths, and is analogous to that predicted previously for magnetic
particles with half-integer spin.


title: All-optical switching in planar semiconductor microcavities

abstract:
  Using a microscopic many-particle theory, we propose all-optical switching in
planar semiconductor microcavities where a weak beam switches a stronger
signal. Based on four-wave-mixing instabilities, the general scheme is a
semiconductor adaptation of a recently demonstrated switch in an atomic vapor
[Dawes et al., Science 308, 672 (2005)].


title:
A two-armed pattern in flickering maps of the nova-like variable UU
  Aquarii

abstract:
  We report the analysis of a uniform sample of 31 light curves of the
nova-like variable UU Aqr with eclipse mapping techniques. The data were
combined to derive eclipse maps of the average steady-light component, the
long-term brightness changes, and low- and high-frequency flickering
components. The long-term variability responsible for the 'low' and 'high'
brightness states is explained in terms of the response of a viscous disk to
changes of 20-50 per cent in the mass transfer rate from the donor star. Low-
and high-frequency flickering maps are dominated by emission from two
asymmetric arcs reminiscent of those seen in the outbursting dwarf nova IP Peg,
and are similarly interpreted as manifestation of a tidally-induced spiral
shock wave in the outer regions of a large accretion disk. The asymmetric arcs
are also seen in the map of the steady-light aside of the broad brightness
distribution of a roughly steady-state disk. The arcs account for 25 per cent
of the steady-light flux and are a long-lasting feature in the accretion disk
of UU Aqr. We infer an opening angle of 10+/-3 degrees for the spiral arcs. The
results suggest that the flickering in UU Aqr is caused by turbulence generated
after the collision of disk gas with the density-enhanced spiral wave in the
accretion disk.


title:
Collective motion of self-propelled particles interacting without
  cohesion

abstract:
  We present a comprehensive study of Vicsek-style self-propelled particle
models in two and three space dimensions. The onset of collective motion in
such stochastic models with only local alignment interactions is studied in
detail and shown to be discontinuous (first-order like). The properties of the
ordered, collectively moving phase are investigated. In a large domain of
parameter space including the transition region, well-defined high-density and
high-order propagating solitary structures are shown to dominate the dynamics.
Far enough from the transition region, on the other hand, these objects are not
present. A statistically-homogeneous ordered phase is then observed, which is
characterized by anomalously-strong density fluctuations, superdiffusion, and
strong intermittency.


title: An axiomatic approach to intrinsic dimension of a dataset

abstract:
  We perform a deeper analysis of an axiomatic approach to the concept of
intrinsic dimension of a dataset proposed by us in the IJCNN'07 paper
(arXiv:cs/0703125). The main features of our approach are that a high intrinsic
dimension of a dataset reflects the presence of the curse of dimensionality (in
a certain mathematically precise sense), and that dimension of a discrete
i.i.d. sample of a low-dimensional manifold is, with high probability, close to
that of the manifold. At the same time, the intrinsic dimension of a sample is
easily corrupted by moderate high-dimensional noise (of the same amplitude as
the size of the manifold) and suffers from prohibitevely high computational
complexity (computing it is an $NP$-complete problem). We outline a possible
way to overcome these difficulties.


title: Charge density wave formation in $R_{2}$Te$_{5}$ ($R$=Nd, Sm and Gd)

abstract:
  The rare earth ($R$) tellurides $R_2$Te$_5$ have a crystal structure
intermediate between that of $R$Te$_2$ and $R$Te$_3$, consisting of alternating
single and double Te planes sandwiched between $R$Te block layers. We have
successfully grown single crystals of Nd$_2$Te$_5$, Sm$_2$Te$_5$ and
Gd$_2$Te$_5$ from a self flux, and describe here the first evidence for charge
density wave formation in these materials. The superlattice patterns for all
three compounds are relatively complex, consisting at room temperature of at
least two independent wavevectors. Consideration of the electronic structure
indicates that to a large extent these wave vectors are separately associated
with sheets of the Fermi surface which are principally derived from the single
and double Te layers.


title:
Dissipation in finite systems: Semiconductor NEMS, graphene NEMS, and
  metallic nanoparticles

abstract:
  This thesis studies three kinds of mesoscopic systems and how one of their
collective degrees of freedom is affected by a dissipative environment:
a)Nanoelectromechanical systems based on semiconductor materials, and how
surface friction processes limit the quality factor of their vibrational
eigenmodes at low temperatures, causing as well a frequency shift; b)Graphene -
based nanoresonators, and several damping mechanisms limiting the quality
factor of its fundamental bending (flexural) eigenmode, and c)The dissipative
dynamics of the surface plasmon created in a metallic nanocluster by a laser
pulse, discussing the validity and limitations of a very common theoretical
model used for its description.


title:
Bias Properties of Extragalactic Distance Indicators XII: Bias Effects
  of Slope Differences and Intrinsic Dispersion on Tully-Fisher Distances to
  Galaxy Clusters with Application to the Virgo Cluster

abstract:
  The Teerikorpi incompleteness bias in the distance modulus of a galaxy
cluster that is determined from incomplete data using the Tully-Fisher (TF)
method is discussed differently than has been done in earlier papers of this
series. A toy cluster is made with zero intrinsic TF dispersion but with slopes
that differ between the calibrators and the cluster data, showing the bias
caused by incorrect slopes. Intrinsic dispersion is added to the model and two
strategies are used to analyze the data; first by binning the data by line
width and then by apparent magnitude (the direct method), and second by binning
by magnitude and then summing over all line widths (the inverse method). To
illustrate these strategies, a composite cluster is made by combining the
observations of Virgo A and B subclusters with those for the Ursa Major I and
II clusters, corrected to the Virgo A distance. The cluster data are calibrated
using Cepheid distances to 25 galaxies that have adequate TF properties.
Different moduli calculated with varying completeness limits are displayed. The
cluster modulus derived from the complete cluster sample gives (m-M) = 31.42
+/- 0.2 (external) for Virgo A, 31.80 +/- 0.16 for Virgo B, 31.26 +/- 0.13 for
UMa I, and 31.58 +/- 0.17 for UMa II. Combining the Virgo A distance (D = 19.2
Mpc that has a range from 17.5 to 21.1 Mpc with its expansion velocity of 1175
+/- 50 km/s as tied to the remote kinematic frame gives a Hubble constant of
61km/s/Mpc with a range from 53 to 70.


title:
Correlation between the transition temperature and the superfluid
  density in BCS superconductor NbB_2+x

abstract:
  The results of the muon-spin rotation experiments on BCS superconductors
NbB_2+x (x = 0.2, 0.34) are reported. Both samples, studied in the present
work, exhibit rather broad transitions to the superconducting state, suggesting
a distribution of the volume fractions with different transition temperatures
(T_c)'s. By taking these distributions into account, the dependence of the
inverse squared zero-temperature magnetic penetration depth (\lambda_0^{-2}) on
T_c was reconstructed for temperatures in the range 1.5K<T_c<8.0K.
\lambda_0^{-2} was found to obey the power law dependence \lambda_0^{-2}\propto
T_c^{3.1(1)} which appears to be common for some families of BCS
superconductors as, {\it e.g.}, Al doped MgB_2 and high-temperature cuprate
superconductors as underdoped YBa_2Cu_3O_{7-\delta}.


title: A mechanistic model for +1 frameshifts in eubacteria

abstract:
  This work applies the methods of signal processing and the concepts of
control system design to model the maintenance and modulation of reading frame
in the process of protein synthesis. The model shows how translational speed
can modulate translational accuracy to accomplish programmed +1 frameshifts and
could have implications for the regulation of translational efficiency. A
series of free energy estimates were calculated from the ribosome's interaction
with mRNA sequences during the process of translation elongation in eubacteria.
A sinusoidal pattern of roughly constant phase was detected in these free
energy signals. Signal phase was identified as a useful parameter for locating
programmed +1 frameshifts encoded in bacterial genes for release factor 2. A
displacement model was developed that captures the mechanism of frameshift
based on the information content of the signal parameters and the relative
abundance of tRNA in the bacterial cell. Results are presented using
experimentally verified frameshift genes across eubacteria.


title: Cohomology of Lie 2-groups

abstract:
  In this paper we study the cohomology of (strict) Lie 2-groups. We obtain an
explicit Bott-Shulman type map in the case of a Lie 2-group corresponding to
the crossed module $A\to 1$. The cohomology of the Lie 2-groups corresponding
to the universal crossed modules $G\to \Aut(G)$ and $G\to \Aut^+(G)$ is the
abutment of a spectral sequence involving the cohomology of $GL(n,\Z)$ and
$SL(n,\Z)$. When the dimension of the center of $G$ is less than 3, we compute
explicitly these cohomology groups. We also compute the cohomology of the Lie
2-group corresponding to a crossed module $G\to H$ whose kernel is compact and
cokernel is connected, simply connected and compact and apply the result to the
string 2-group.


title:
Analytic models of ultra-cold atomic collisions at negative energies for
  application to confinement-induced resonances

abstract:
  We construct simple analytic models of the $S$-matrix, accounting for both
scattering resonances and smooth background contributions for collisions that
occur below the s-wave threshold. Such models are important for studying
confinement-induced resonances such as those occurring in cold collisions of
$^{133}$Cs atoms in separated sites of a polarization-gradient optical lattice.
Because these resonances occur at negative energy with respect to the s-wave
threshold, they cannot be studied easily using direct numerical solutions of
the Schr\"{o}dinger equation. Using our analytic model, we extend previous
studies of negative-energy scattering to the multichannel case, accounting for
the interplay of Feshbach resonances, large background scattering lengths, and
inelastic processes.


title:
First-principles Predictor of the Location of Ergodic-Non-ergodic
  Transitions

abstract:
  This letter presents a remarkably simple approach to the first-principles
determination of the ergodic-non-ergodic transition in monodisperse colloidal
suspensions. It consists of an equation for the long-time asymptotic value
$\gamma$ of the mean squared displacement of the colloidal particles, whose
finite real solutions signal the non-ergodic state, and determines the
non-ergodic parameter $f(k)$. We illustrate its concrete application to three
simple model colloidal systems, namely, hard-spheres, hard-spheres plus
repulsive (screened Coulomb) Yukawa interaction, and hard-sphere plus
attractive Yukawa tail. The results indicate that this is quite a competitive
theory, similar in spirit to, but conceptually independent from, the well-known
mode coupling theory.


title: On Character Amenability of Banach Algebras

abstract:
  Associated to a nonzero homomorphism $\varphi$ of a Banach algebra $A$, we
regard special functionals, say $m_\varphi$, on certain subspaces of $A^\ast$
which provide equivalent statements to the existence of a bounded right
approximate identity in the corresponding maximal ideal in $A$. For instance,
applying a fixed point theorem yields an equivalent statement to the existence
of a $m_\varphi$ on $A^\ast$; and, in addition we expatiate the case that if a
functional $m_\varphi$ is unique, then $m_\varphi$ belongs to the topological
center of the bidual algebra $A^{\ast\ast}$. An example of a function algebra,
surprisingly, contradicts a conjecture that a Banach algebra $A$ is amenable if
$A$ is $\varphi$-amenable in every character $\varphi$ and if functionals
$m_\varphi$ associated to the characters $\varphi$ are uniformly bounded.
Aforementioned are also elaborated on the direct sum of two given Banach
algebras.


title:
Improved parameters for the transiting planet HD 17156b: a high-density
  giant planet with a very eccentric orbit

abstract:
  We report high-precision transit photometry for the recently detected planet
HD 17156b. Using these new data with previously published transit photometry
and radial velocity measurements, we perform a combined analysis based on a
Markov Chain Monte Carlo approach. The resulting mass M_p = 3.09 (+0.22-0.17)
M_Jup and radius R_p = 1.23 (+0.17-0.20) R_Jup for the planet places it at the
outer edge of the density distribution of known transiting planets with rho_p =
1.66 (+1.37-0.60) rho_Jup. The obtained transit ephemeris is T_tr =
2454438.48271 (+0.00077-0.00057) + N x 21.21747 (+0.00070-0.00067) BJD. The
derived plausible tidal circularization time scales for HD 17156b are larger
than the age of the host star. The measured high orbital eccentricity e =
0.6719 (+0.0052-0.0063) can thus not be interpreted as the clear sign of the
presence of another body in the system.


title: Flavorful Supersymmetry

abstract:
  Weak scale supersymmetry provides elegant solutions to many of the problems
of the standard model, but it also generically gives rise to excessive flavor
and CP violation. We show that if the mechanism that suppresses the Yukawa
couplings also suppresses flavor changing interactions in the supersymmetry
breaking parameters, essentially all the low energy flavor and CP constraints
can be satisfied. The standard assumption of flavor universality in the
supersymmetry breaking sector is not necessary. We study signatures of this
framework at the LHC. The mass splitting among different generations of squarks
and sleptons can be much larger than in conventional scenarios, and even the
mass ordering can be changed. We find that there is a plausible scenario in
which the NLSP is a long-lived right-handed selectron or smuon decaying into
the LSP gravitino. This leads to the spectacular signature of monochromatic
electrons or muons in a stopper detector, providing strong evidence for the
framework.


title:
($\ell,0)$-Carter partitions, a generating function, and their crystal
  theoretic interpretation

abstract:
  In this paper we give an alternate combinatorial description of the
"$(\ell,0)$-JM partitions" (see \cite{F}) that are also $\ell$-regular. Our
main theorem is the equivalence of our combinatoric and the one introduced by
James and Mathas (\cite{JM}). The condition of being an $(\ell,0)$-JM partition
is fundamentally related to the hook lengths of the partition. The
representation-theoretic significance of their combinatoric on an
$\ell$-regular partition is that it indicates the irreducibility of the
corresponding specialized Specht module over the finite Hecke algebra (see
\cite{JM}). We use our result to find a generating series which counts the
number of such partitions, with respect to the statistic of a partition's first
part. We then apply our description of these partitions to the crystal graph
$B(\Lambda_0)$ of the basic representation of $\hat{\mathfrak{sl}_{\ell}}$,
whose nodes are labeled by $\ell$-regular partitions. Here we give a fairly
simple crystal-theoretic rule which generates all $\ell$-regular $(\ell,0)$-JM
partitions in the graph $B(\Lambda_0)$. Finally, we mention how our
construction can be generalized to recent results of M. Fayers (see \cite{F})
and S. Lyle (see \cite{L}) to count the total number of (not necessarily
$\ell$-regular) Specht modules which stay irreducible at a primitive $\ell$th
root of unity (for $\ell >2$).


title: On the irreducible representations of a finite semigroup

abstract:
  Work of Clifford, Munn and Ponizovski{\u\i} parameterized the irreducible
representations of a finite semigroup in terms of the irreducible
representations of its maximal subgroups. Explicit constructions of the
irreducible representations were later obtained independently by Rhodes and
Zalcstein and by Lallement and Petrich. All of these approaches make use of
Rees's theorem characterizing 0-simple semigroups up to isomorphism. Here we
provide a short modern proof of the Clifford-Munn-Ponizovski{\u\i} result based
on a lemma of J. A. Green, which allows us to circumvent the theory of 0-simple
semigroups. A novelty of this approach is that it works over any base ring.


title: The Formation of Constellation III in the Large Magellanic Cloud

abstract:
  We present a detailed reconstruction of the star-formation history of the
Constellation III region in the Large Magellanic Cloud, to constrain the
formation mechanism of this enigmatic feature. Star formation in Constellation
III seems to have taken place during two distinct epochs: there is the 8-15 Myr
epoch that had previously been recognized, but we also see strong evidence for
a separate "burst" of star formation 25-30 Myr ago. The "super-supernova" or
GRB blast wave model for the formation of Constellation III is difficult to
reconcile with such an extended, two-epoch star formation history, because the
shock wave should have induced star formation throughout the structure
simultaneously, and any unconsumed gas would quickly be dissipated, leaving
nothing from which to form a subsequent burst of activity. We propose a "truly
stochastic" self-propagating star formation model, distinct from the canonical
model in which star formation proceeds in a radially-directed wave from the
center of Constellation III to its perimeter. As others have noted, and we now
confirm, the bulk age gradients demanded by such a model are simply not present
in Constellation III. In our scenario, the prestellar gas is somehow pushed
into these large-scale arc structures, without simultaneously triggering
immediate and violent star formation throughout the structure. Rather, star
formation proceeds in the arc according to the local physical conditions of the
gas. Self-propagating star formation is certainly possible, but in a truly
stochastic manner, without a directed, large scale pattern.


title:
Algebraic Solution of the Harmonic Oscillator With Minimal Length
  Uncertainty Relations

abstract:
  In quantum mechanics with minimal length uncertainty relations the
Heisenberg-Weyl algebra of the one-dimensional harmonic oscillator is a
deformed SU(1,1) algebra. The eigenvalues and eigenstates are constructed
algebraically and they form the infinite-dimensional representation of the
deformed SU(1,1) algebra. Our construction is independent of prior knowledge of
the exact solution of the Schr\"odinger equation of the model. The approach can
be generalized to the $D$-dimensional oscillator with non-commuting
coordinates.


title:
Phenomenological analysis of the nucleon spin contents and their scale
  dependence

abstract:
  In the past few years, a lot of evidences have been accumulated, which
indicate that the gluon polarization inside the nucleon is likely to be small
at least at the low renormalization scales. On the other hand, the recent
lattice QCD analyses suggest that the net orbital angular momentum carried by
the quarks is nearly zero. There is also some indication noticed by Brodsky and
Gardner based on the COMPASS observation of small single-spin asymmetry on the
isoscalar deuteron target, that the gluon orbital angular momentum inside the
nucleon is likely to be small. Naively combining all these observations, we are
led to a rather embarrassing conclusion that the nucleon constituents
altogether do not carry enough amount of angular momentum saturating the total
nucleon spin. We show that this somewhat confused state of affairs can be
cleared up only by paying careful attention to the scale dependencies of the
nucleon spin decomposition.


title: Homotopy groups of the spaces of self-maps of Lie groups

abstract:
  We compute the homotopy groups of the spaces of self maps of Lie groups of
rank 2, SU(3), Sp(2), and G_2. We use the cell structures of these Lie groups
and the standard methods of homotopy theory.


title:
Missing monopole strength of the Hoyle state in the inelastic
  $\alpha$+$^{12}$C scattering

abstract:
  Analyses of the inelastic $\alpha$+$^{12}$C scattering at medium energies
have indicated that the strength of the Hoyle state (the isoscalar 0$^+_2$
excitation at 7.65 MeV in $^{12}$C) seems to exhaust only 7 to 9% of the
monopole energy weighted sum rule (EWSR), compared to about 15% of the EWSR
extracted from inelastic electron scattering data. The full monopole transition
strength predicted by realistic microscopic $\alpha$-cluster models of the
Hoyle state can be shown to exhaust up to 22% of the EWSR. To explore the
missing monopole strength in the inelastic $\alpha$+$^{12}$C scattering, we
have performed a fully microscopic folding model analysis of the inelastic
$\alpha$+$^{12}$C scattering at $E_{\rm lab}=104$ to 240 MeV using the
3-$\alpha$ resonating group wave function of the Hoyle state obtained by
Kamimura, and a complex density-dependent M3Y interaction newly parametrized
based on the Brueckner Hartree Fock results for nuclear matter. Our folding
model analysis has shown consistently that the missing monopole strength of the
Hoyle state is not associated with the uncertainties in the analysis of the
$\alpha$+$^{12}$C scattering, but is most likely due to the short lifetime and
weakly bound structure of this state which significantly enhances absorption in
the exit $\alpha$+$^{12}$C$^*(0^+_2)$ channel.


title: Diffusion of Colloidal Fluids in Random Porous Media

abstract:
  A simple manner to describe the diffusive relaxation of a colloidal fluid
adsorbed in a porous medium is to model the porous medium as a set of spherical
particles fixed in space at random positions with prescribed statistical
structural properties. Within this model one may describe the relaxation of
concentration fluctuations of the adsorbed fluid by simply setting to zero the
short-time mobility of one species (the porous matrix) in a theory of the
dynamics of equilibrium colloidal mixtures, or by extending such dynamic theory
to explicitly consider the porous matrix as a random external field. Here we
consider the first approach and employ the self-consistent generalized Langevin
equation (SCGLE) theory of the dynamics of equilibrium colloidal mixtures, to
describe the dynamics of the mobile component. We conclude that if the correct
static structure factors are provided as input, the SCGLE theory correctly
predicts the main features of the dynamics of the permeating fluid.


title: VoIP over Multiple IEEE 802.11 Wireless LANs

abstract:
  Prior work indicates that 802.11 is extremely inefficient for VoIP transport.
Only 12 and 60 VoIP sessions can be supported in an 802.11b and an 802.11g
WLAN, respectively. This paper shows that the bad news does not stop there.
When there are multiple WLANs in the vicinity of each other, the already-low
VoIP capacity can be further eroded in a significant manner. For example, in a
5-by-5, 25-cell multi-WLAN network, the VoIP capacities for 802.11b and 802.11g
are only 1.63 and 10.34 sessions per AP, respectively. This paper investigates
several solutions to improve the VoIP capacity. Based on a conflict graph
model, we propose a clique-analytical call-admission scheme, which increases
the VoIP capacity by 52% and 37% in 802.11b and 802.11g respectively. If all
the three orthogonal frequency channels available in 11b and 11g are used, the
capacity can be nearly tripled by the call-admission scheme. This paper also
proposes for the first time the use of coarse-grained time-division multiple
access (CoTDMA) in conjunction with the basic 802.11 CSMA to eliminate the
performance-degrading exposed-node and hidden-node problems. We find that
CoTDMA can further increase the VoIP capacity in the multi-WLAN scenario by an
additional 35%.


title:
Semi-Clifford operations, structure of $\mathcal{C}_k$ hierarchy, and
  gate complexity for fault-tolerant quantum computation

abstract:
  Teleportation is a crucial element in fault-tolerant quantum computation and
a complete understanding of its capacity is very important for the practical
implementation of optimal fault-tolerant architectures. It is known that
stabilizer codes support a natural set of gates that can be more easily
implemented by teleportation than any other gates. These gates belong to the so
called $\mathcal{C}_k$ hierarchy introduced by Gottesman and Chuang (Nature
\textbf{402}, 390). Moreover, a subset of $\mathcal{C}_k$ gates, called
semi-Clifford operations, can be implemented by an even simpler architecture
than the traditional teleportation setup (Phys. Rev. \textbf{A62}, 052316).
However, the precise set of gates in $\mathcal{C}_k$ remains unknown, even for
a fixed number of qubits $n$, which prevents us from knowing exactly what
teleportation is capable of. In this paper we study the structure of
$\mathcal{C}_k$ in terms of semi-Clifford operations, which send by conjugation
at least one maximal abelian subgroup of the $n$-qubit Pauli group into another
one. We show that for $n=1,2$, all the $\mathcal{C}_k$ gates are semi-Clifford,
which is also true for $\{n=3,k=3\}$. However, this is no longer true for
$\{n>2,k>3\}$. To measure the capability of this teleportation primitive, we
introduce a quantity called `teleportation depth', which characterizes how many
teleportation steps are necessary, on average, to implement a given gate. We
calculate upper bounds for teleportation depth by decomposing gates into both
semi-Clifford $\mathcal{C}_k$ gates and those $\mathcal{C}_k$ gates beyond
semi-Clifford operations, and compare their efficiency.


title: Riesz transforms in one dimension

abstract:
  We study the boundedness on $L^p$ of the Riesz transform $\nabla L^{-1/2}$,
where $L$ is one of several operators defined on $\R$ or $\R_+$, endowed with
the measure $r^{d-1} dr$, $d > 1$, where $dr$ is Lebesgue measure. For integer
$d$, this mimics the measure on Euclidean $d$-dimensional space, and in this
case our setup is equivalent to looking at the Laplacian acting on radial
functions on Euclidean space or variations of Euclidean space such as the
exterior of a sphere (with either Dirichlet or Neumann boundary conditions), or
the connected sum of two copies of $\R^d$. In this way we illuminate some
recent results on the Riesz transform on asymptotically Euclidean manifolds.
  We are however interested in all real values of $d > 1$, and another goal of
our analysis is to study the range of boundedness as a function of $d$; it is
particularly interesting to see the behaviour as $d$ crosses 2. For example, in
one of our cases which models radial functions on the connected sum of two
copies of $\R^d$, the upper threshold for $L^p$ boundedness is $p=d$ for $d \ge
2$ and $p=d/(d-1)$ for $d < 2$. Only in the case $d=2$ is the Riesz transform
actually bounded on $L^p$ when $p$ is equal to the upper threshold.
  We also study the Riesz transform when we have an inverse square potential,
or a delta function potential; these cases provide a simple model for recent
results of the first author and Guillarmou. Finally we look at the Hodge
projector in a slightly more general setup.


title: On weak and strong magnetohydrodynamic turbulence

abstract:
  Recent numerical and observational studies contain conflicting reports on the
spectrum of magnetohydrodynamic turbulence. In an attempt to clarify the issue
we investigate anisotropic incompressible magnetohydrodynamic turbulence with a
strong guide field $B_0$. We perform numerical simulations of the reduced MHD
equations in a special setting that allows us to elucidate the transition
between weak and strong turbulent regimes. Denote $k_{\|}$, $k_\perp$
characteristic field-parallel and field-perpendicular wavenumbers of the
fluctuations, and $b_{\lambda}$ the fluctuating field at the scale $\lambda\sim
1/k_{\perp}$. We find that when the critical balance condition, $k_{\|}B_0\sim
k_{\perp} b_{\lambda}$, is satisfied, the turbulence is strong, and the energy
spectrum is $E(k_{\perp})\propto k^{-3/2}_{\perp}$. As the $k_{\|}$ width of
the spectrum increases, the turbulence rapidly becomes weaker, and in the limit
$k_{\|}B_0\gg k_{\perp} b_{\lambda}$, the spectrum approaches
$E(k_{\perp})\propto k_{\perp}^{-2}$. The observed sensitivity of the spectrum
to the balance of linear and nonlinear interactions may explain the conflicting
numerical and observational findings where this balance condition is not well
controlled.

categories: astro-ph nlin.CD physics.flu-dyn physics.plasm-ph


title: On the Berstein-Svarc Theorem in dimension 2

abstract:
  We prove that for any group of the cohomological dimension $n$ the $n$th
power of the Berstein class of the group is nontrivial. This allows to prove
the following Berstein-Svarc theorem for all $n$:
  Theorem. For a connected complex $X$ with $\dim X=\cat X=n$, the $n$th power
of the Berstein class of $X$ is nontrivial.
  Previously it was known for $n\ge 3$.
  We also prove that, for every map $f: M \to N$ of degree $\pm 1$ of closed
orientable manifolds, the fundamental group of $N$ is free provided that the
fundamental group of $M$ is.


title:
Financial Variables Effect on the U.S. Gross Private Domestic Investment
  (GPDI) 1959-2001

abstract:
  I studied what role the US stock markets and money markets have possibly
played in the Gross Private Domestic Investment (GPDI) of the United States
from the year 1959 to the year 2001, Gross Private Domestic Investment refers
to the total amount of investment spending by businesses and firms located
within the borders of a nation. It includes both the values of the purchases of
non-residential fixed investment, which include capital goods used for
production, and the values of the purchases of residential fixed investment,
which include construction spending for factories or offices. And I created a
Multiple Linear Regression Model of the GDPI. To see if companies and private
citizens use the stock market and money markets as a way of financing capital
projects (business ventures, buying commercial and noncommercial property,
etc).
  Keywords: Gross Private Domestic Investment, Pearson Correlation, SP 500, TB3


title: Highly-asymmetric soliton complexes in parabolic optical lattices

abstract:
  We introduce multipole soliton complexes in optical lattices induced by
nondiffracting parabolic beams. Despite the symmetry-breaking dictated by the
curvature of the lattice channels, we find that complex, asymmetric
higher-order states can be stable. The unique topology of parabolic lattices
affords new types of soliton motion: single solitons launched into the lattice
with nonzero transverse momentum perform periodic oscillations along parabolic
paths.


title: Indeterminacy of Spatiotemporal Cardiac Alternans

abstract:
  Cardiac alternans, a beat-to-beat alternation in action potential duration
(at the cellular level) or in ECG morphology (at the whole heart level), is a
marker of ventricular fibrillation, a fatal heart rhythm that kills hundreds of
thousands of people in the US each year. Investigating cardiac alternans may
lead to a better understanding of the mechanisms of cardiac arrhythmias and
eventually better algorithms for the prediction and prevention of such dreadful
diseases. In paced cardiac tissue, alternans develops under increasingly
shorter pacing period. Existing experimental and theoretical studies adopt the
assumption that alternans in homogeneous cardiac tissue is exclusively
determined by the pacing period. In contrast, we find that, when calcium-driven
alternans develops in cardiac fibers, it may take different spatiotemporal
patterns depending on the pacing history. Because there coexist multiple
alternans solutions for a given pacing period, the alternans pattern on a fiber
becomes unpredictable. Using numerical simulation and theoretical analysis, we
show that the coexistence of multiple alternans patterns is induced by the
interaction between electrotonic coupling and an instability in calcium
cycling.


title: Asymptotic distributions and chaos for the supermarket model

abstract:
  In the supermarket model there are n queues, each with a unit rate server.
Customers arrive in a Poisson process at rate \lambda n, where 0<\lambda <1.
Each customer chooses d > 2 queues uniformly at random, and joins a shortest
one. It is known that the equilibrium distribution of a typical queue length
converges to a certain explicit limiting distribution as n -> oo. We quantify
the rate of convergence by showing that the total variation distance between
the equilibrium distribution and the limiting distribution is essentially of
order n^{-1}; and we give a corresponding result for systems starting from
quite general initial conditions (not in equilibrium). Further, we quantify the
result that the systems exhibit chaotic behaviour: we show that the total
variation distance between the joint law of a fixed set of queue lengths and
the corresponding product law is essentially of order at most n^{-1}.


title: Bessel models for $GSp(4)$

abstract:
  Methods of theta correspondence are used to analyze local and global Bessel
models for $GSp(4)$ proving a conjecture of Gross and Prasad which describes
these models in terms of local epsilon factors in the local case, and the
non-vanishing of central critical $L$-value in the global case.


title: Effective Lagrangian of unitary Fermi gas from $\varepsilon$ expansion

abstract:
  Using $\varepsilon$ expansion technique proposed in \cite{Nishida:2006br} we
derive an effective Lagrangian (Ginzburg-Landau-like functional) of the
degenerate unitary Fermi gas to the next-to-leading (NLO) order in
$\varepsilon.$ It is demonstrated that for many realistic situations it is
sufficient to retain leading order (LO) terms in the derivative expansion. The
functional is used to study vortex structure in the symmetric gas, and
interface between normal and superfluid phases in the polarized gas. The
resulting surface free energy is about four times larger than the value
previously quoted in the literature.


title: Hinged Dissections Exist

abstract:
  We prove that any finite collection of polygons of equal area has a common
hinged dissection. That is, for any such collection of polygons there exists a
chain of polygons hinged at vertices that can be folded in the plane
continuously without self-intersection to form any polygon in the collection.
This result settles the open problem about the existence of hinged dissections
between pairs of polygons that goes back implicitly to 1864 and has been
studied extensively in the past ten years. Our result generalizes and indeed
builds upon the result from 1814 that polygons have common dissections (without
hinges). We also extend our common dissection result to edge-hinged dissections
of solid 3D polyhedra that have a common (unhinged) dissection, as determined
by Dehn's 1900 solution to Hilbert's Third Problem. Our proofs are
constructive, giving explicit algorithms in all cases. For a constant number of
planar polygons, both the number of pieces and running time required by our
construction are pseudopolynomial. This bound is the best possible, even for
unhinged dissections. Hinged dissections have possible applications to
reconfigurable robotics, programmable matter, and nanomanufacturing.


title:
Fractional quantum Hall effect at $\nu = 5/2$: Ground states,
  non-Abelian quasiholes, and edge modes in a microscopic model

abstract:
  We present a comprehensive numerical study of a microscopic model of the
fractional quantum Hall system at filling fraction $\nu = 5/2$, based on the
disc geometry. Our model includes Coulomb interaction and a semi-realistic
confining potential. We also mix in some three-body interaction in some cases
to help elucidate the physics. We obtain a phase diagram, discuss the
conditions under which the ground state can be described by the Moore-Read
state, and study its competition with neighboring stripe phases. We also study
quasihole excitations and edge excitations in the Moore-Read--like state. From
the evolution of edge spectrum, we obtain the velocities of the charge and
neutral edge modes, which turn out to be very different. This separation of
velocities is a source of decoherence for a non-Abelian quasihole/quasiparticle
(with charge $\pm e/4$) when propagating at the edge; using numbers obtained
from a specific set of parameters we estimate the decoherence length to be
around four microns. This sets an upper bound for the separation of the two
point contacts in a double point contact interferometer, designed to detect the
non-Abelian nature of such quasiparticles. We also find a state that is a
potential candidate for the recently proposed anti-Pfaffian state. We find the
speculated anti-Pfaffian state is favored in weak confinement (smooth edge)
while the Moore-Read Pfaffian state is favored in strong confinement (sharp
edge).


title: An Example of Constructing Versal Deformation for Leibniz Algebras

abstract:
  In this work we compute a versal deformation of the three dimensional
nilpotent Leibniz algebra over $\mathbb{C}$, defined by the nontrivial brackets
$[e_1,e_3]=e_2$ and $[e_3,e_3]=e_1$.


title: Chaotic oscillations in a map-based model of neural activity

abstract:
  We propose a discrete time dynamical system (a map) as phenomenological model
of excitable and spiking-bursting neurons. The model is a discontinuous
two-dimensional map. We find condition under which this map has an invariant
region on the phase plane, containing chaotic attractor. This attractor creates
chaotic spiking-bursting oscillations of the model. We also show various
regimes of other neural activities (subthreshold oscillations, phasic spiking
etc.) derived from the proposed model.


title:
Phase field simulations of coupled phase transformations in
  ferroelastic-ferroelastic nanocomposites

abstract:
  We use phase field simulations to study composites made of two different
ferroelastics (e.g., two types of martensite). The deformation of one material
due to a phase transformation can elastically affect the other constituent and
induce it to transform as well. We show that the phase transformation can then
occur above its normal critical temperature and even higher above this
temperature in nanocomposites than in bulk composites. Microstructures depend
on temperature, on the thickness of the layers, and on the crystal structure of
the two constituents -- certain nanocomposites exhibit a great diversity of
microstructures not found in bulk composites. Also, the periodicity of the
martensite twins may vary over 1 order of magnitude based on geometry.
keywords: Ginzburg-Landau, martensitic transformation, multi-ferroics,
nanostructure, shape-memory alloy


title: MRI/TRUS data fusion for brachytherapy

abstract:
  BACKGROUND: Prostate brachytherapy consists in placing radioactive seeds for
tumour destruction under transrectal ultrasound imaging (TRUS) control. It
requires prostate delineation from the images for dose planning. Because
ultrasound imaging is patient- and operator-dependent, we have proposed to fuse
MRI data to TRUS data to make image processing more reliable. The technical
accuracy of this approach has already been evaluated. METHODS: We present work
in progress concerning the evaluation of the approach from the dosimetry
viewpoint. The objective is to determine what impact this system may have on
the treatment of the patient. Dose planning is performed from initial TRUS
prostate contours and evaluated on contours modified by data fusion. RESULTS:
For the eight patients included, we demonstrate that TRUS prostate volume is
most often underestimated and that dose is overestimated in a correlated way.
However, dose constraints are still verified for those eight patients.
CONCLUSIONS: This confirms our initial hypothesis.


title:
Medical image computing and computer-aided medical interventions applied
  to soft tissues. Work in progress in urology

abstract:
  Until recently, Computer-Aided Medical Interventions (CAMI) and Medical
Robotics have focused on rigid and non deformable anatomical structures.
Nowadays, special attention is paid to soft tissues, raising complex issues due
to their mobility and deformation. Mini-invasive digestive surgery was probably
one of the first fields where soft tissues were handled through the development
of simulators, tracking of anatomical structures and specific assistance
robots. However, other clinical domains, for instance urology, are concerned.
Indeed, laparoscopic surgery, new tumour destruction techniques (e.g. HIFU,
radiofrequency, or cryoablation), increasingly early detection of cancer, and
use of interventional and diagnostic imaging modalities, recently opened new
challenges to the urologist and scientists involved in CAMI. This resulted in
the last five years in a very significant increase of research and developments
of computer-aided urology systems. In this paper, we propose a description of
the main problems related to computer-aided diagnostic and therapy of soft
tissues and give a survey of the different types of assistance offered to the
urologist: robotization, image fusion, surgical navigation. Both research
projects and operational industrial systems are discussed.


title:
Euler equation of the optimal trajectory for the fastest magnetization
  reversal of nano-magnetic structures

abstract:
  Based on the modified Landau-Lifshitz-Gilbert equation for an arbitrary
Stoner particle under an external magnetic field and a spin-polarized electric
current, differential equations for the optimal reversal trajectory, along
which the magnetization reversal is the fastest one among all possible reversal
routes, are obtained. We show that this is a Euler-Lagrange problem with
constrains. The Euler equation of the optimal trajectory is useful in designing
a magnetic field pulse and/or a polarized electric current pulse in
magnetization reversal for two reasons. 1) It is straightforward to obtain the
solution of the Euler equation, at least numerically, for a given magnetic
nano-structure characterized by its magnetic anisotropy energy. 2) After
obtaining the optimal reversal trajectory for a given magnetic nano-structure,
finding a proper field/current pulse is an algebraic problem instead of the
original nonlinear differential equation.


title: Prime spectrum and primitive Leavitt path algebras

abstract:
  In this paper a bijection between the set of prime ideals of a Leavitt path
algebra $L_K(E)$ and a certain set which involves maximal tails in $E$ and the
prime spectrum of $K[x,x^{-1}]$ is established. Necessary and sufficient
conditions on the graph $E$ so that the Leavitt path algebra $L_K(E)$ is
primitive are also found.


title: Hilltop Curvatons

abstract:
  We study ``hilltop'' curvatons that evolve on a convex potential. Hilltop
curvatons evolving on the Hubble-induced potential are generic if supergravity
is assumed in the theory. We do not consider curvatons whose potential is
protected from $O(H)$ corrections, where $H$ is the Hubble parameter. We assume
that the effective mass of a curvaton is expressed as $m_\sigma = c H$, where
the coefficient varies within $0.2 \le c \le 5$ depending on the circumstances.
A negative mass term may lead to enhancement of curvaton fluctuation, which has
a significant impact on the energy bound for low-scale inflation. Using a
simple curvaton model and following the conventional curvaton hypothesis, we
demonstrate the generality of this enhancement.


title: Symplectic Heegaard splittings and linked abelian groups

abstract:
  Let $f$ be the gluing map of a Heegaard splitting of a 3-manifold $W$. The
goal of this paper is to determine the information about $W$ contained in the
image of $f$ under the symplectic representation of the mapping class group. We
prove three main results. First, we show that the first homology group of the
three manifold together with Seifert's linking form provides a complete set of
stable invariants. Second, we give a complete, computable set of invariants for
these linking forms. Third, we show that a slight augmentation of Birman's
determinantal invariant for a Heegaard splitting gives a complete set of
unstable invariants.


title: Non-special scrolls with general moduli

abstract:
  In this paper we study smooth, non-special scrolls S of degree d, genus g,
with general moduli. In particular, we study the scheme of unisecant curves of
a given degree on S. Our approach is mostly based on degeneration techniques.


title: Brill-Noether theory and non-special scrolls

abstract:
  In this paper we study the Brill-Noether theory of sub-line bundles of a
general, stable rank-two vector bundle on a curve C with general moduli. We
relate this theory to the geometry of unisecant curves on smooth, non-special
scrolls with hyperplane sections isomorphic to C. Most of our results are based
on degeneration techniques.


title:
Kondo volume collapse, Kondo breakdown, and Fermi surface transitions in
  heavy-fermion metals

abstract:
  The unconventional critical behavior near magnetic quantum phase transitions
in various heavy-fermion metals, apparently inconsistent with the standard
spin-density-wave scenario, has triggered proposals on the breakdown of the
Kondo effect at the critical point. Here we investigate, within one specific
scenario, the fate of such a zero-temperature transition upon coupling of the
electronic to lattice degrees of freedom. We study a Kondo-Heisenberg model
with volume-dependent Kondo coupling -- this model displays both Kondo volume
collapse and Kondo-breakdown transitions, as well as Lifshitz transitions
associated with a change of the Fermi-surface topology. Within a large-N
treatment, we find that the Lifshitz transition tends to merge with the Kondo
volume collapse and hence becomes first order, whereas the Kondo breakdown
transition remains of second order except for very soft lattices. Interesting
physics emerges at the zero-temperature endpoint of the Kondo volume collapse:
For electrons in two space dimensions, this endpoint is located at the Lifshitz
line for a large range of parameters, thus two continuous quantum phase
transitions coincide without fine tuning. We analyze the effective Landau
theory for such a situation and discuss critical exponents. Finally, we relate
our findings to current heavy-fermion experiments.


title: An Illustrated Introduction to the Basic Biological Principles

abstract:
  Both external environmental selection and internal lower-level evolution are
essential for an integral picture of evolution. This paper proposes that the
division of internal evolution into DNA/RNA pattern formation (genotype) and
protein functional action (phenotype) resolves a universal conflict between
fitness and evolvability. Specifically, this paper explains how this universal
conflict drove the emergence of genotype-phenotype division, why this labor
division is responsible for the extraordinary complexity of life, and how the
specific ways of genotype-phenotype mapping in the labor division determine the
paths and forms of evolution and development.


title:
Breakdown of an intermediate plateau in the magnetization process of
  anisotropic spin-1 Heisenberg dimer: theory vs. experiment

abstract:
  The magnetization process of the spin-1 Heisenberg dimer model with axial and
rhombic single-ion anisotropy terms is particularly investigated in connection
with recent experimental high-field measurements performed on the
single-crystal sample of the homodinuclear nickel(II) compound
[Ni2(Medpt)2(ox)(H2O)2](ClO4)2.2H2O (Medpt=methyl-bis(3-aminopropyl)amine). The
results obtained from the exact numerical diagonalization reveal a striking
magnetization process with a marked spatial dependence on the applied magnetic
field for arbitrary but non-zero single-ion anisotropy. It is demonstrated that
the field range, which corresponds to an intermediate magnetization plateau
emerging at a half of the saturation magnetization, basically depends on
single-ion anisotropy terms as well as a spatial orientation of the applied
field. The breakdown of the intermediate magnetization plateau is discussed at
length in relation to the single-ion anisotropy strength.


title: Near-field cosmology with the VLT

abstract:
  With the arrival of wide-field imagers on medium-size telescopes (e.g.
SkyMapper, Pan-STARRS) and the future co-existence of LSST with the E-ELT, it
is worthwhile to evaluate the scientific potential of a CCD camera with ~1
degree FOV for the VLT. Here we discuss the role that such an instrument could
play in resolving persisting fundamental problems in "near-field cosmology".


title: The prototype colliding-wind pinwheel WR 104

abstract:
  Results from the most extensive study of the time-evolving dust structure
around the prototype "Pinwheel" nebula WR 104 are presented. Encompassing 11
epochs in three near-infrared filter bandpasses, a homogeneous imaging data set
spanning more than 6 years (or 10 orbits) is presented. Data were obtained from
the highly successful Keck Aperture Masking Experiment, which can recover high
fidelity images at extremely high angular resolutions, revealing the geometry
of the plume with unprecedented precision. Inferred properties for the
(unresolved) underlying binary and wind system are orbital period 241.5 +/- 0.5
days and angular outflow velocity of 0.28 +/- 0.02 mas/day. An optically thin
cavity of angular size 13.3 +/- 1.4 mas was found to lie between the central
binary and the onset of the spiral dust plume. Rotational motion of the wind
system induced by the binary orbit is found to have important ramifications:
entanglement of the winds results in strong shock activity far downstream from
the nose of the bowshock. The far greater fraction of the winds participating
in the collision may play a key role in gas compression and the nucleation of
dust at large radii from the central binary and shock stagnation point.
Investigation of the effects of radiative braking pointed towards significant
modifications of the simple hydrostatic colliding wind geometry, extending the
relevance of this phenomena to wider binary systems than previously considered.
Limits placed on the maximum allowed orbital eccentricity of e < 0.06 argue
strongly for a prehistory of tidal circularization in this system. Finally we
discuss the implications of Earth's polar (i < 16 deg) vantage point onto a
system likely to host supernova explosions at future epochs.


title: Dirichlet sets and Erdos-Kunen-Mauldin theorem

abstract:
  By a theorem proved by Erdos, Kunen and Mauldin, for any nonempty perfect set
$P$ on the real line there exists a perfect set $M$ of Lebesgue measure zero
such that $P+M=\mathbb{R}$. We prove a stronger version of this theorem in
which the obtained perfect set $M$ is a Dirichlet set. Using this result we
show that for a wide range of familes of subsets of the reals, all additive
sets are perfectly meager in transitive sense. We also prove that every proper
analytic subgroup $G$ of the reals is contained in an F-sigma set $F$ such that
$F+G$ is a meager null set.


title: On the deployment of Mobile Trusted Modules

abstract:
  In its recently published TCG Mobile Reference Architecture, the TCG Mobile
Phone Work Group specifies a new concept to enable trust into future mobile
devices. For this purpose, the TCG devises a trusted mobile platform as a set
of trusted engines on behalf of different stakeholders supported by a physical
trust-anchor. In this paper, we present our perception on this emerging
specification. We propose an approach for the practical design and
implementation of this concept and how to deploy it to a trustworthy operating
platform. In particular we propose a method for the take-ownership of a device
by the user and the migration (i.e., portability) of user credentials between
devices.


title: The Uehling correction in muonic atoms exactly in Z\alpha

abstract:
  The Uehling correction to the energy levels is presented in terms of the
hypergeometric functions 2F1. This presentation allows to derived various
asymptotics and approximations. Further applications of this method to other
atomic characteristics are also considered.


title: A statistical framework for the analysis of microarray probe-level data

abstract:
  In microarray technology, a number of critical steps are required to convert
the raw measurements into the data relied upon by biologists and clinicians.
These data manipulations, referred to as preprocessing, influence the quality
of the ultimate measurements and studies that rely upon them. Standard
operating procedure for microarray researchers is to use preprocessed data as
the starting point for the statistical analyses that produce reported results.
This has prevented many researchers from carefully considering their choice of
preprocessing methodology. Furthermore, the fact that the preprocessing step
affects the stochastic properties of the final statistical summaries is often
ignored. In this paper we propose a statistical framework that permits the
integration of preprocessing into the standard statistical analysis flow of
microarray data. This general framework is relevant in many microarray
platforms and motivates targeted analysis methods for specific applications. We
demonstrate its usefulness by applying the idea in three different applications
of the technology.


title:
X-ray spectral evolution of TeV BL Lac objects: eleven years of
  observations with BeppoSAX, XMM-Newton and SWIFT satellites

abstract:
  Many of the extragalactic sources detected in $\gamma$ rays at TeV energies
are BL Lac objects. In particular, they belong to the subclass of ``high
frequency peaked BL Lacs" (HBLs), as their spectral energy distributions
exhibit a first peak in the X-ray band. At a closer look, their X-ray spectra
appear to be generally curved into a log-parabolic shape. In a previous
investigation of Mrk 421, two correlations were found between the spectral
parameters. One involves the height $S_p$ increasing with the position $E_p$ of
the first peak; this was interpreted as a signature of synchrotron emission
from relativistic electrons. The other involves the curvature parameter $b$
decreasing as $E_p$ increases; this points toward statistical/stochastic
acceleration processes for the emitting electrons. We analyse X-ray spectra of
several TeV HBLs to pinpoint their behaviours in the $E_p-S_p$ and $E_p-b$
planes and to compare them with Mrk 421. We perfom X-ray spectral analyses of a
sample of 15 BL Lacs. We report the whole set of observations obtained with the
\sax, \xmm and \swf satellites between 29/06/96 and 07/04/07. We focus on five
sources (PKS 0548-322, 1H 1426+418, Mrk 501, 1ES 1959+650, PKS2155-304) whose
X-ray observations warrant detailed searching of correlations or trends. Within
our database, we find that four out of five sources, namely PKS 0548-322, 1H
1426+418, Mrk 501 and 1ES 1959+650, follow similar trends as Mrk 421 in the
$E_p-S_p$ plane, while PKS 2155-304 differs. As for the $E_p-b$ plane, all TeV
HBLs follow a similar behaviour. The trends exhibited by Mrk 421 appear to be
shared by several TeV HBLs, such as to warrant discussing predictions from the
X-ray spectral evolution to that of TeV emissions.


title:
Long-term magnetic activity in close binary systems. I. Patterns of
  color variations

abstract:
  We present the results of a long-term photometric monitoring project carried
out at Catania Astrophysical Observatory and aimed at studying magnetic
activity in close binary systems. We present the complete observations dataset
(38,000 photoelectric observations in UBV) and new results of an investigation
on the origin of brightness and color variations observed in the close binary
stars: AR Psc, VY Ari, UX Ari, V711 Tau, EI Eri, V1149 Ori, DH Leo, HU Vir, RS
CVn, V775 Her, AR Lac, SZ Psc, II Peg and BY Dra. Correlation and regression
analyses are carried out. We find the existence of two different patterns of
color variations. Eight stars in our sample: BY Dra, VY Ari, V775 Her, II Peg,
V1149 Ori, HU Vir, EI Eri and DH Leo become redder when they get fainter. The
other six stars show the opposite behaviour, i.e. they become bluer when they
get fainter. For V711 Tau this behaviour could be explained by the increased
relative U- and B- flux contribution by the earlier-type component of the
binary system when the cooler component gets fainter. On the other hand, for AR
Psc, UX Ari, RS CVn, SZ Psc and AR Lac the existence of hot photospheric
faculae must be necessarily invoked. We also found that in single-lined and
double-lined binary stars in which the fainter component is inactive or much
less active the V magnitude is correlated to B-V and U-B color variations in
more than 60% of observation seasons. The correlation is found in less than 40%
of observation seasons when the fainter component has a non-negligible level of
activity and/or hot faculae are present but they are either spatially or
temporally uncorrelated to spots.


title:
Proposal for an experiment to search for Randall-Sundrum type
  corrections to Newton's law of gravitation

abstract:
  String theory, as well as the string inspired brane-world models such as the
Randall-Sundrum (RS) one, suggest a modification of Newton's law of gravitation
at small distance scales. Search for modifications of standard gravity is an
active field of research in this context. It is well known that short range
corrections to gravity would violate the Newton-Birkhoff theorem. Based on
calculations of RS type non-Newtonian forces for finite size spherical bodies,
we propose a torsion balance based experiment to search for the effects of
violation of this celebrated theorem valid in Newtonian gravity as well as the
general theory of relativity. We explain the main principle behind the
experiment and provide detailed calculations suggesting optimum values of the
parameters of the experiment. The projected sensitivity is sufficient to probe
the Randall-Sundrum parameter up to 10 microns.


title:
Stability of toroidal magnetic fields in the solar tachocline and
  beneath

abstract:
  Stability of toroidal magnetic field in a stellar radiation zone is
considered for the cases of uniform and differential rotation. In the rigidly
rotating radiative core shortly below the tachocline, the critical magnetic
field for instability is about 600 G. The unstable disturbances for slightly
supercritical fields have short radial scales ~1 Mm. Radial mixing produced by
the instability is estimated to conclude that the internal field of the sun can
exceed the critical value of 600 G only marginally. Otherwise, the mixing is
too strong and not compatible with the observed lithium abundance. Analysis of
joint instability of differential rotation and toroidal field leads to the
conclusion that axisymmetric models of the laminar solar tachocline are stable
to nonaxisymmetric disturbances. The question of whether sun-like stars can
posses tachoclines is addressed with positive answer for stars with rotation
periods shorter than about two months.


title: Activity cycle of the giant star of Z Andromedae and its spin period

abstract:
  We have reanalyzed the long-term optical light curve (LC) of the symbiotic
star Z Andromedae, covering 112--yr of mostly visual observations. Two strictly
periodic and one quasi-periodic cycles can be identified in this LC. A P1=7550
d quasi periodicity characterizes the repetition time of the outburst episodes
of this symbiotic star. Six such events have been recorded so far. During
quiescence states of the system, i.e. in time intervals between outbursts, the
LC is clearly modulated by a stable coherent period of P2=759.1 d. This is the
well known orbital period of the Z And binary system that have been measured
also spectroscopically. A third coherent period of P3=658.4 d is modulating the
intense fluctuations in the optical brightness of the system during outbursts.
We attribute the trigger of the outbursts phenomenon and the clock that drives
it, to a solar type magnetic dynamo cycle that operates in the convection and
the outer layers of the giant star of the system. We suggest that the intense
surface activity of the giant star during maximum phases of its magnetic cycle
is especially enhanced in one or two antipode regions, fixed in the atmosphere
of the star and rotating with it. Such spots could be active regions around the
North and the South poles of a general magnetic dipole field of the star. The
P3 periodicity is half the beat of the binary orbital period of the system and
the spin period of the giant. The latter is then either 482 or 1790 d. If only
one pole is active on the surface of the giant, P3 is the beat period itself,
and the spin period is 352 d. It could also be 5000 d if the giant is rotating
in retrograde direction. We briefly compare these findings in the LC of Z And
to similar modulations that were identified in the LC of two other prototype
symbiotics, BF Cyg and YY Her.


title:
Synchronized and Desynchronized Phases of Exciton-Polariton Condensates
  in the Presence of Disorder

abstract:
  Condensation of exciton-polaritons in semiconductor microcavities takes place
despite in plane disorder. Below the critical density the inhomogeneity of the
potential seen by the polaritons strongly limits the spatial extension of the
ground state. Above the critical density, in presence of weak disorder, this
limitation is spontaneously overcome by the non linear interaction, resulting
in an extended synchronized phase. This mechanism is clearly evidenced by
spatial and spectral studies, coupled to interferometric measurements. In case
of strong disorder, several non phase-locked (independent) condensates can be
evidenced. The transition from synchronized phase to desynchronized phase is
addressed considering multiple realizations of the disorder.


title:
On the existence of homomorphisms between principal series of complex
  semisimple Lie groups

abstract:
  We determine when there exists a nonzero homomorphism between principal
series representations of a complex semisimple Lie group. We also determines
the existence of homomorphisms between twisted Verma modules.


title: Conformal Metrics with Constant Q-Curvature

abstract:
  We consider the problem of varying conformally the metric of a four
dimensional manifold in order to obtain constant $Q$-curvature. The problem is
variational, and solutions are in general found as critical points of saddle
type. We show how the problem leads naturally to consider the set of formal
barycenters of the manifold.


title:
Describing disability through individual-level mixture models for
  multivariate binary data

abstract:
  Data on functional disability are of widespread policy interest in the United
States, especially with respect to planning for Medicare and Social Security
for a growing population of elderly adults. We consider an extract of
functional disability data from the National Long Term Care Survey (NLTCS) and
attempt to develop disability profiles using variations of the Grade of
Membership (GoM) model. We first describe GoM as an individual-level mixture
model that allows individuals to have partial membership in several mixture
components simultaneously. We then prove the equivalence between
individual-level and population-level mixture models, and use this property to
develop a Markov Chain Monte Carlo algorithm for Bayesian estimation of the
model. We use our approach to analyze functional disability data from the
NLTCS.


title: On an identity by Chaundy and Bullard. I

abstract:
  An identity by Chaundy and Bullard writes 1/(1-x)^n (n=1,2,...) as a sum of
two truncated binomial series. This identity was rediscovered many times.
Notably, a special case was rediscovered by I. Daubechies, while she was
setting up the theory of wavelets of compact support. We discuss or survey many
different proofs of the identity, and also its relationship with Gauss
hypergeometric series. We also consider the extension to complex values of the
two parameters which occur as summation bounds. The paper concludes with a
discussion of a multivariable analogue of the identity, which was first given
by Damjanovic, Klamkin and Ruehr. We give the relationship with Lauricella
hypergeometric functions and corresponding PDE's. The paper ends with a new
proof of the multivariable case by splitting up Dirichlet's multivariable beta
integral.


title: Atmospheric neutrino and Long Baseline neutrino experiments

abstract:
  The results obtained by several experiments on atmospheric neutrino
oscillations are summarized and discussed. Then the results obtained by
different long baseline neutrino experiments are considered. Finally
conclusions and perspectives are made.


title:
Spatial coupling of particle and fluid models for streamers: where
  nonlocality matters

abstract:
  Particle models for streamer ionization fronts contain correct electron
energy distributions, runaway effects and single electron statistics.
Conventional fluid models are computationally much more efficient for large
particle numbers, but create too low ionization densities in high fields. To
combine their respective advantages, we here show how to couple both models in
space. We confirm that the discrepancies between particle and fluid fronts
arise from the steep electron density gradients in the leading edge of the
fronts. We find the optimal position for the interface between models that
minimizes computational effort and reproduces the results of a pure particle
model.


title: Functional-integral representation of atomic mixtures

abstract:
  A mixture of spin-1/2 fermionic atoms and molecules of paired fermionic atoms
is studied in an optical lattice. The molecules are formed by an attractive
nearest-neighbor interaction. A functional integral is constructed for this
many-body system and analyzed in terms of a mean-field approximation and
Gaussian fluctuations. This provides a phase diagram with the two merging Mott
insulators and an intermediate superfluid. The Gaussian fluctuations give rise
to an induced repulsive dimer-dimer interaction mediated by the unpaired
fermions. The effect of an unbalanced distribution of spin-up and spin-down
fermions is also discussed.


title: Distances in random Apollonian network structures

abstract:
  In this paper, we study the distribution of distances in random Apollonian
network structures (RANS), a family of graphs which has a one-to-one
correspondence with planar ternary trees. Using multivariate generating
functions that express all information on distances, and singularity analysis
for evaluating the coefficients of these functions, we describe the
distribution of distances to an outermost vertex, and show that the average
value of the distance between any pair of vertices in a RANS of order n is
asymptotically square root of n.


title:
Diverse correlation structures in gene expression data and their utility
  in improving statistical inference

abstract:
  It is well known that correlations in microarray data represent a serious
nuisance deteriorating the performance of gene selection procedures. This paper
is intended to demonstrate that the correlation structure of microarray data
provides a rich source of useful information. We discuss distinct correlation
substructures revealed in microarray gene expression data by an appropriate
ordering of genes. These substructures include stochastic proportionality of
expression signals in a large percentage of all gene pairs, negative
correlations hidden in ordered gene triples, and a long sequence of weakly
dependent random variables associated with ordered pairs of genes. The reported
striking regularities are of general biological interest and they also have
far-reaching implications for theory and practice of statistical methods of
microarray data analysis. We illustrate the latter point with a method for
testing differential expression of nonoverlapping gene pairs. While designed
for testing a different null hypothesis, this method provides an order of
magnitude more accurate control of type 1 error rate compared to conventional
methods of individual gene expression profiling. In addition, this method is
robust to the technical noise. Quantitative inference of the correlation
structure has the potential to extend the analysis of microarray data far
beyond currently practiced methods.


title:
Andreev reflections at large ferromagnet/high-T_C superconductor area
  junctions with rough interface

abstract:
  Sub-gap conductance at a large area junction with a rough interface of a
ferromagnet and a high-T$_{C}$ superconductor is superimposed by multiple peaks
which is not expected from an ideal point contact Andreev reflection process.
We demonstrate this phenomenon by measuring resistance as a function of bias
voltage of a Co/Y$_{1}$Ba$_{2}$Cu$_{3}$O$_{7-\delta}$ junction with contact
area 50 x 70 $\mu$ $m^{2}$ at various temperatures. In order to analyze such
Andreev reflection data, the interface is assumed to have random potentials
which can create local electric fields. The Blonder-Tinkham-Klapwijk theory is
modified with the inclusion of a broadening parameter due to finite life time
effects of quasi particles. An additional voltage drop due to local electric
fields at the rough interface has been included in terms of an extra energy
shift which may be related to the asymmetry of normalized resistance data. Spin
polarization has been introduced for the ferromagnet. The presented model
explains the multi-peak nature and asymmetry of Andreev reflection data
experimentally observed at large area junctions. Extension of the model also
interprets the experimentally observed anomalous enhancement of resistance
peaks in the sub-gap region which may result from crossing the critical current
limit across the junction.


title:
Jacobi osculating rank and isotropic geodesics on naturally reductive
  3-manifolds

abstract:
  We study the Jacobi osculating rank of geodesics on naturally reductive
homogeneous manifolds and we apply this theory to the 3-dimensional case. Here,
each non-symmetric, simply connected naturally reductive 3-manifold can be
given as a principal bundle over a surface of constant curvature, such that the
curvature of its horizontal distribution is also a constant. Then, we prove
that the Jacobi osculating rank of every geodesic is two except for the Hopf
fibers, where it is zero. Moreover, we determine all isotropic geodesics and
the isotropic tangent conjugate locus.