title: Twins Among the Low Mass Spectroscopic Binaries

abstract:
  We report an analysis of twins of spectral types F or later in the 9th
Catalog of Spectroscopic Binaries (SB9). Twins, the components of binaries with
mass ratio within 2% of 1.0, are found among the binaries with primaries of F
and G spectral type. They are most prominent among the binaries with periods
less than 43 days, a cutoff first identified by Lucy. Within the subsample of
binaries with P<43 days, the twins do not differ from the other binaries in
their distributions of periods (median P~7d), masses, or orbital
eccentricities. Combining the mass ratio distribution in the SB9 in the mass
range 0.6 to 0.85 Msun with that measured by Mazeh et al. for binaries in the
Carney-Latham high proper motion survey, we estimate that the frequency of
twins in a large sample of spectroscopic binaries is about 3%. Current
theoretical understanding indicates that accretion of high specific angular
momentum material by a protobinary tends to equalize its masses. We speculate
that the excess of twins is produced in those star forming regions where the
accretion processes were able to proceed to completion for a minority of
protobinaries. This predicts that the components of a young twin may appear to
differ in age and that, in a sample of spectroscopic binaries in a star
formation region, the twins are, on average, older than the binaries with mass
ratios much smaller than 1.


title: Efficient multiparticle entanglement via asymmetric Rydberg blockade

abstract:
  We present an efficient method for producing $N$ particle entangled states
using Rydberg blockade interactions. Optical excitation of Rydberg states that
interact weakly, yet have a strong coupling to a second control state is used
to achieve state dependent qubit rotations in small ensembles. On the basis of
quantitative calculations we predict that an N=8 Schr\"odinger cat state can be
produced with a fidelity of 84% in cold Rb atoms.


title: Categorical centers and Reshetikhin-Turaev invariants

abstract:
  The center Z(C) of a spherical fusion category C (over an arbitrary
commutative ring) is modular. We give an algorithm for computing the
Reshetikhin-Turaev invariant defined with Z(C). It is based on Hopf diagrams
and an explicit description of the structure of the coend of Z(C).


title: Heavy flavor operator matrix elements at $O(a_s^3)$

abstract:
  The heavy quark effects in deep--inelastic scattering in the asymptotic
regime $Q^2 \gg m^2$ can be described by heavy flavor operator matrix elements.
Complete analytic expressions for these objects are currently known to ${\sf
NLO}$. We present first results for fixed moments at ${\sf NNLO}$. This
involves a recalculation of fixed moments of the corresponding ${\sf NNLO}$
anomalous dimensions, which we thereby confirm.


title:
Analytic solutions of the geodesic equation in higher dimensional static
  spherically symmetric space-times

abstract:
  The complete analytical solutions of the geodesic equation of massive test
particles in higher dimensional Schwarzschild, Schwarzschild-(anti)de Sitter,
Reissner-Nordstroem and Reissner-Nordstroem-(anti)de Sitter space--times are
presented. Using the Jacobi inversion problem restricted to the theta divisor
the explicit solution is given in terms of Kleinian sigma functions. The
derived orbits depend on the structure of the roots of the characteristic
polynomials which depend on the particle's energy and angular momentum, on the
mass and the charge of the gravitational source, and the cosmological constant.
We discuss the general structure of the orbits and show that due to the
specific dimension-independent form of the angular momentum and the
cosmological force a rich variety of orbits can emerge only in four and five
dimensions. We present explicit analytical solutions for orbits up to 11
dimensions. A particular feature of Reissner--Nordstroem space-times is that
bound and escape orbits traverse through different universes.


title:
Matrix Factorizations, Massey Products and F-Terms for Two-Parameter
  Calabi-Yau Hypersurfaces

abstract:
  We discuss B-type tensor product branes in mirrors of two-parameter
Calabi-Yau hypersurfaces, using the language of matrix factorizations. We
determine the open string moduli of the branes at the Gepner point. By turning
on both bulk and boundary moduli we then deform the brane away from the Gepner
point. Using the deformation theory of matrix factorizations we compute Massey
products. These contain the information about higher order deformations and
obstructions. The obstructions are encoded in the F-term equations, which we
obtain from the Massey product algorithm. We show that the F-terms can be
integrated to an effective superpotential. Our results provide an ingredient
for open/closed mirror symmetry for these hypersurfaces.


title: Comment on "Casimir energies with finite-width mirrors"

abstract:
  We comment on a recent publication [1] by Fosco, Lombardo and Mazzitelli on
Casimir energies for material slabs (`finite width mirrors') and report a
discrepancy between results obtained there for a single mirror and some
previous calculations. We provide a simple consistency check which proves that
the method used in [1] is not reliable when applied to approximations of
piecewise constant profile of the mirror. We also present an alternative method
for calculation of the Casimir energy in such systems based on our recent work.
Our results coincide both with perturbation theory and with some older
\cite{Bordag'95} and more recent \cite{Vassilevitch'08} calculations, but
differ from those of [1].


title: Spiky strings in AdS_3 x S^1 and their AdS-pp-wave limits

abstract:
  We study a class of classical solutions for closed strings moving in AdS_3 x
S^1 part of AdS_5 x S^5 with energy E and spin S in AdS_3 and angular momentum
J and winding m in S^1. They have rigid shape with n spikes in AdS_3. We find
that when J or m are non-zero, the spikes do not end in cusps. We consider in
detail a special large n limit in which S ~ n^2, J ~ n, i.e. S >> J >> 1, with
(E+S)/ n^2, (E-S)/ n, J/n, m/n staying finite. In that limit the spiky spinning
string approaches the boundary of AdS_5. We show that the corresponding
solution can be interpreted as describing a periodic-spike string moving in
AdS_3 --pp-wave x S^1 background. The resulting expression for the string
energy should represent a strong-coupling prediction for anomalous dimension of
a class of dual gauge theory states in a particular thermodynamic limit of the
SL(2) spin chain.


title: Spectral norm of products of random and deterministic matrices

abstract:
  We study the spectral norm of matrices M that can be factored as M=BA, where
A is a random matrix with independent mean zero entries, and B is a fixed
matrix. Under the (4+epsilon)-th moment assumption on the entries of A, we show
that the spectral norm of such an m by n matrix M is bounded by \sqrt{m} +
\sqrt{n}, which is sharp. In other words, in regard to the spectral norm,
products of random and deterministic matrices behave similarly to random
matrices with independent entries. This result along with the previous work of
M. Rudelson and the author implies that the smallest singular value of a random
m times n matrix with i.i.d. mean zero entries and bounded (4+epsilon)-th
moment is bounded below by \sqrt{m} - \sqrt{n-1} with high probability.


title: On the Dec group of finite abelian Galois extensions over global fields

abstract:
  If K/F is a finite abelian Galois extension of global fields whose Galois
group has exponent t, we prove that there exists a short exact sequence that
has as a consequence that if t is square free, then Dec(K/F)=Br_{t}(K/F) which
we use to show that prime exponent division algebras over Henselian valued
fields with global residue fields are isomorphic to a tensor product of cyclic
algebras. Finally, we construct a counterexample to the result for higher
exponent division algebras.


title: On the characterization of algebraically integrable plane foliations

abstract:
  We give a characterization theorem for non-degenerated plane foliations of
degree different from 1 having a rational first integral. Moreover, we prove
that the degree $r$ of a non-degenerated foliation as above provides the
minimum number, $r+1$, of points in the projective plane through which
infinitely many algebraic leaves of the foliation go.


title: Searle's "Dualism Revisited"

abstract:
  A recent article in which John Searle claims to refute dualism is examined
from a scientific perspective.


title:
Comment on "Observation of neutronless fusion reactions in picosecond
  laser plasmas"

abstract:
  The paper by Belyaev et al. [Phys. Rev. E {\bf 72}, 026406 (2005)] reported
the first experimental observation of alpha particles produced in the
thermonuclear reaction $^{11}$B($p,\alpha$)$^{8}$Be induced by
laser-irradiation on a $^{11}$B polyethylene (CH$_2$) composite target. The
laser used in the experiment is characterized by a picosecond pulse duration
and a peak of intensity of 2$\times10^{18}$ W/cm$^2$. We suggest that both the
background-reduction method adopted in their detection system and the choice of
the detection energy region of the reaction products are possibly inadequate.
Consequently the total yield reported underestimates the true yield. Based on
their observation, we give an estimation of the total yield to be higher than
their conclusion, i.e., of the order of 10$^5 \alpha$ per shot.

categories: physics.plasm-ph nucl-ex nucl-th physics.space-ph


title:
Uniform WKB approximation of Coulomb wave functions for arbitrary
  partial wave

abstract:
  Coulomb wave functions are difficult to compute numerically for extremely low
energies, even with direct numerical integration. Hence, it is more convenient
to use asymptotic formulas in this region. It is the object of this paper to
derive analytical asymptotic formulas valid for arbitrary energies and partial
waves. Moreover, it is possible to extend these formulas for complex values of
parameters.


title:
Enhanced Wavelet Analysis of Solar Magnetic Activity with Comparison to
  Global Temperature and the Central England Temperature Record

abstract:
  The continuous wavelet transform may be enhanced by deconvolution with the
wavelet response function. After correcting for the cone-of-influence, the
power spectral density of the solar magnetic record as given by the derectified
yearly sunspot number is calculated, revealing a spectrum of odd harmonics of
the fundamental Hale cycle, and the integrated instant power is compared to a
reconstruction of global temperature in a normalized scatter plot displaying a
positive correlation after the turn of the twentieth century. Comparison of the
spectrum with that obtained from the Central England Temperature record
suggests that some features are shared while others are not, and the scatter
plot again indicates a possible correlation.


title:
Importance of fluctuations of cross sections in muon-catalysed t-t
  fusion reactions

abstract:
  We discuss the reaction rate of the muon-catalysed $t$-$t$ fusion. The
reaction rate is determined as a function of the temperature using the model of
"in flight" fusion. We especially take into account the effect of the
fluctuation of the cross section due to the existence of the muon. The obtained
reaction rate 5.0$\times10^{-3} \mu$s$^{-1}$ is a factor of 10$^{-3}$ smaller
than the experimental muonic cycling rate in the solid tritium target.


title: Liquidity Risk, Price Impacts and the Replication Problem

abstract:
  We extend a linear version of the liquidity risk model of Cetin et al. (2004)
to allow for price impacts. We show that the impact of a market order on prices
depends on the size of the transaction and the level of liquidity. We obtain a
simple characterization of self-financing trading strategies and a sufficient
condition for no arbitrage. We consider a stochastic volatility model in which
the volatility is partly correlated with the liquidity process and show that,
with the use of variance swaps, contingent claims whose payoffs depend on the
value of the asset can be approximately replicated in this setting. The
replicating costs of such payoffs are obtained from the solutions of BSDEs with
quadratic growth and analytical properties of these solutions are investigated.


title:
Determination of the minimum masses of heavy elements in the envelopes
  of Jupiter and Saturn

abstract:
  We calculate the minimum mass of heavy elements required in the envelopes of
Jupiter and Saturn to match the observed oversolar abundances of volatiles.
Because the clathration efficiency remains unknown in the solar nebula, we have
considered a set of sequences of ice formation in which the fraction of water
available for clathration is varied between 0 and 100 %. In all the cases
considered, we assume that the water abundance remains homogeneous whatever the
heliocentric distance in the nebula and directly derives from a gas phase of
solar composition. Planetesimals then form in the feeding zones of Jupiter and
Saturn from the agglomeration of clathrates and pure condensates in proportions
fixed by the clathration efficiency. A fraction of Kr and Xe may have been
sequestrated by the H3+ ion in the form of stable XeH3+ and KrH3+ complexes in
the solar nebula gas phase, thus implying the formation of at least partly Xe-
and Kr-impoverished planetesimals in the feeding zones of Jupiter and Saturn.
These planetesimals were subsequently accreted and vaporized into the hydrogen
envelopes of Jupiter and Saturn, thus engendering volatiles enrichments in
their atmospheres, with respect to hydrogen. Taking into account both
refractory and volatile components, and assuming plausible molecular mixing
ratios in the gas phase of the outer solar nebula, we show that it is possible
to match the observed enrichments in Jupiter and Saturn, whatever the
clathration efficiency. Our calculations predict that the O/H enrichment
decreases from 6.7 to 5.6 times solar (O/H) in the envelope of Jupiter and from
18.1 to 15.4 times solar (O/H) in the envelope of Saturn with the growing
clathration efficiency in the solar nebula.


title: Dark matter from SUGRA GUTs: mSUGRA, NUSUGRA and Yukawa-unified SUGRA

abstract:
  Gravity-mediated SUSY breaking models with R-parity conservation give rise to
dark matter in the universe. I review neutralino dark matter in the minimal
supergravity model (mSUGRA), models with non-universal soft SUSY breaking terms
(NUSUGRA) which yield a well-tempered neutralino, and models with unified
Yukawa couplings at the GUT scale (as may occur in an SO(10) SUSY GUT theory).
These latter models have difficulty accommodating neutralino dark matter, but
work very well if the dark matter particles are axions and axinos.


title: The double of a Hopf monad

abstract:
  The center Z(C) of an autonomous category C is monadic over C (if certain
coends exist in C). The notion of Hopf monad naturally arises if one tries to
reconstruct the structure of Z(C) in terms of its monad Z: we show that Z is a
quasitriangular Hopf monad on C and Z(C) is isomorphic to the braided category
Z-C of Z-modules. More generally, let T be a Hopf monad on an autonomous
category C. We construct a Hopf monad Z_T on C, the centralizer of T, and a
canonical distributive law of T over Z_T. By Beck's theory, this has two
consequences. On one hand, D_T=Z_T T is a quasitriangular Hopf monad on C,
called the double of T, and Z(T-C)= D_T-C as braided categories. As an
illustration, we define the double D(A) of a Hopf algebra A in a braided
autonomous category in such a way that the center of the category of A-modules
is the braided category of D(A)-modules (generalizing the Drinfeld double). On
the other hand, the canonical distributive law also lifts Z_T to a Hopf monad
on T-C which gives the coend of T-C. Hence, for T=Z, an explicit description of
the Hopf algebra structure of the coend of Z(C) in terms of the structural
morphisms of C, which is useful in quantum topology.


title:
Viscosity Solutions and American Option Pricing in a Stochastic
  Volatility Model of the Ornstein-Uhlenbeck Type

abstract:
  In this paper, we study the valuation of American type derivatives in the
stochastic volatility model of Barndorff-Nielsen and Shephard (2001). We
characterize the value of such derivatives as the unique viscosity solution of
an integral-partial differential equation when the payoff function satisfies a
Lipschitz condition.


title:
Characterizing heralded single-photon sources with imperfect measurement
  devices

abstract:
  Any characterization of a single-photon source is not complete without
specifying its second-order degree of coherence, i.e., its $g^{(2)}$ function.
An accurate measurement of such coherence functions commonly requires
high-precision single-photon detectors, in whose absence, only time-averaged
measurements are possible. It is not clear, however, how the resulting
time-averaged quantities can be used to properly characterize the source. In
this paper, we investigate this issue for a heralded source of single photons
that relies on continuous-wave parametric down-conversion. By accounting for
major shortcomings of the source and the detectors--i.e., the multiple-photon
emissions of the source, the time resolution of photodetectors, and our chosen
width of coincidence window--our theory enables us to infer the true source
properties from imperfect measurements. Our theoretical results are
corroborated by an experimental demonstration using a PPKTP crystal pumped by a
blue laser, that results in a single-photon generation rate about 1.2 millions
per second per milliwatt of pump power. This work takes an important step
toward the standardization of such heralded single-photon sources.


title: Charge Transfer in Partition Theory

abstract:
  The recently proposed Partition Theory (PT) [J.Phys.Chem.A 111, 2229 (2007)]
is illustrated on a simple one-dimensional model of a heteronuclear diatomic
molecule. It is shown that a sharp definition for the charge of molecular
fragments emerges from PT, and that the ensuing population analysis can be used
to study how charge redistributes during dissociation and the implications of
that redistribution for the dipole moment. Interpreting small differences
between the isolated parts' ionization potentials as due to environmental
inhomogeneities, we gain insight into how electron localization takes place in
H2+ as the molecule dissociates. Furthermore, by studying the preservation of
the shapes of the parts as different parameters of the model are varied, we
address the issue of transferability of the parts. We find good transferability
within the chemically meaningful parameter regime, raising hopes that PT will
prove useful in chemical applications.


title: Collective Sliding States for Colloidal Molecular Crystals

abstract:
  We study the driving of colloidal molecular crystals over periodic substrates
such as those created with optical traps. The n-merization that occurs in the
colloidal molecular crystal states produces a remarkably rich variety of
distinct dynamical behaviors, including polarization effects within the pinned
phase and the formation of both ordered and disordered sliding phases. Using
computer simulations, we map the dynamic phase diagrams as a function of
substrate strength for dimers and trimers on a triangular substrate, and
correlate features on the phase diagram with transport signatures.


title:
Feeding versus Feedback in NGC 4151 probed with Gemini NIFS. I.
  Excitation

abstract:
  We have used the Gemini Near-infrared Integral Field Spectrograph (NIFS) to
map the emission-line intensity distributions and ratios in the Narrow-Line
Region (NLR) of the Seyfert galaxy NGC 4151 in the Z, J, H and K bands at a
resolving power ~ 5000, covering the inner 200 pc x 300 pc of the galaxy at a
spatial resolution of 8 pc. We present intensity distributions I(r) in 14
emission lines. (1) For the ionized gas, I(r) is extended to ~ 100 pc from the
nucleus along pos. angle PA=60/240 deg-- NE--SW), consistent with an origin in
the known biconical outflow; while for the recombination lines I(r) ~ r^-1, for
the forbidden lines I(r) is flat (r^0). (2) The H_2 emission lines intensity
distributions avoid the region of the bicone, extending to r ~ 60 pc,
perpendicular to the bicone axis, supporting an origin for the H_2-emitting gas
in the galaxy plane. (3) The coronal lines show a steep intensity profile,
described by r^-2. Using the line-ratio maps [Fe II]1.644/1.257 and Pa_b/Br_g
we obtain a reddening of E(B-V)~0.5 along the NLR and E(B-V)>1 at the nucleus.
Our line-ratio map [Fe II] 1.257/[P II] 1.189 is the first such map of an
extragalactic source. Together with the [Fe II]/Pa_b map, these line ratios
correlate with the radio intensity distribution, mapping the effects of shocks
produced by the radio jet, which probably release the Fe locked in grains and
produce the enhancement of the [Fe II] emission observed at ~ 1 arcsec from the
nucleus. At these regions, we obtain densities N_e ~4000 cm^-3 and temperatures
T_e ~ 15000K for the [Fe II]-emitting gas. For the H_2-emitting gas we obtain T
~ 2100K. The distinct intensity distributions, physical properties and
locations of the ionized and molecular gas suggest that the H_2-emitting gas
traces the AGN feeding, while the ionized gas traces its feedback.


title: Market bubbles and crashes

abstract:
  Episodes of market crashes have fascinated economists for centuries. Although
many academics, practitioners and policy makers have studied questions related
to collapsing asset price bubbles, there is little consensus yet about their
causes and effects. This review and essay evaluates some of the hypotheses
offered to explain the market crashes that often follow asset price bubbles.
Starting from historical accounts and syntheses of past bubbles and crashes, we
put the problem in perspective with respect to the development of the efficient
market hypothesis. We then present the models based on heterogeneous agents and
the limits to arbitrage that prevent rational agents from bursting bubbles
before they inflate. Then, we explore another set of explanations of why
rational traders would be led to actually profit from and surf on bubbles, by
anticipating the behavior of noise traders or by realizing the difficulties in
synchronizing their actions. We then end by discussing a complex system
approach of social imitation leading to collective market regimes like herding
and the phenomenon of bifurcation (or phase transition) that rationalize what
crash can occur in unstable market regimes. The key insight is that diagnosing
bubbles may be feasible when taking into account the positive feedback
mechanisms that give rise to transient "super-exponential" price growth, the
bubbles.


title: GMIMS: The Global Magneto-Ionic Medium Survey

abstract:
  The Global Magneto-Ionic Medium Survey (GMIMS) is a project to map the
diffuse polarized emission over the entire sky, Northern and Southern
hemispheres, from 300 MHz to 1.8 GHz. With an angular resolution of 30 - 60
arcmin and a frequency resolution of 1 MHz or better, GMIMS will provide the
first spectro-polarimetric data set of the large-scale polarized emission over
the entire sky, observed with single-dish telescopes. GMIMS will provide an
invaluable resource for studies of the magneto-ionic medium of the Galaxy in
the local disk, halo, and its transition.


title:
Efficacy of Put and Spd sprayed on leaves from Brassica juncea plants
  against Cd2+-induced oxidative stress

abstract:
  The protective effect exerted by polyamines (Put and Spd) against cadmium
(Cd) stress was investigated in Brassica juncea plants. Treatment with CdCl2
(75 micro-Mole) resulted in a rise of Cd accumulation, a decrease of fresh and
dry weights in every plant organ, an increase of free polyamine content at limb
and stem levels as well as a decrease at root level. On the other hand, the
total conjugated polyamine levels in the stem tissues were unaffected by Cd. In
the leaf tissues, this metal caused a reduction of chlorophyll a content, a
rise of guaiacol peroxidase (GPOX) activity and an increase of malondialdehyde
(MDA), soluble glucide, proline and amino acid contents. Exogenous application,
by spraying, of putrescine (Put) and spermidine (Spd) to leaf tissues reduced
CdCl2-induced stress. These polyamines proved to exert a partial, though
significant, protection of the foliar fresh weight and to alleviate the
oxidative stress generated by Cd through reductions of MDA amounts and GPOX
(E.C.1.11.1.7) activity. The enhancement of chlorophyll a content in plants by
Put and those of Chl a and Chl b by Spd both constitute evidences of their
efficacy against the Cd2+-induced loss of pigments. Conversely to Put, Spd
caused a decrease of Cd content in leave tissues and a rise in the stems and
roots; these findings are in favour of a stimulation of Cd uptake by Spd. The
proline stimulation observed with Cd was reduced further to the spraying of Put
onto tissues, but the decrease induced by Spd was more limited. In the plants
treated with Cd, the amino acid contents in the leaves were unaffected by Put
and Spd spraying; on the other hand, Cd2+ disturbed polyamine levels (free and
acido-soluble conjugated-forms); we notice the rise of total free PAs and the
decrease of their conjugated-ones.


title:
Power spectrum of electron number density perturbations at cosmological
  recombination epoch

abstract:
  The power spectrum of number density perturbations of free electrons is
obtained for the epoch of cosmological recombination of hydrogen. It is shown
that amplitude of the electron perturbations power spectrum of scales larger
than acoustic horizon exceeds by factor of 17 the amplitude of baryon matter
density ones (atoms and ions of hydrogen and helium). In the range of the first
and second acoustic peaks such relation is 18, in the range of the third one
16. The dependence of such relations on cosmological parameters is analysed
too.


title: Autocatalytic MBE growth of GaAs nanowires on oxidized Si(100)

abstract:
  GaAs nanowires were grown by molecular beam epitaxy on Si(100) substrates
covered with 5 nm SiO2. The growth was performed with As4 at low, close to
stoichiometric, As4/Ga flux ratio, using Ga nanodroplets as catalyst. The
nanowires are found to be in epitaxial relation to the Si substrate due to
contact via pinholes through the SiO2 layer. The nanowires are up to 15
micrometers long and have diameters of about 100 nm, the catalyzing Ga
nanodroplets are observed at their tops.


title:
On the statistical physics of directed polymers in a random medium and
  their relation to tree codes

abstract:
  Using well-known results from statistical physics, concerning the almost-sure
behavior of the free energy of directed polymers in a random medium, we prove
that random tree codes achieve the distortion-rate function almost surely under
a certain symmetry condition.


title: Theorem on best Diophantine approximations for linear forms

abstract:
  We prove a new quantitative result on the degeneracy of the dimension of the
subspace spanned by the best Diophantine approximations for a linear form.


title: Efficient perturbation theory for quantum lattice models

abstract:
  We present a novel approach to long-range correlations beyond dynamical
mean-field theory through a ladder approximation to dual fermions. The new
technique is applied to the two-dimensional Hubbard model. We demonstrate that
the transformed perturbation series for the nonlocal dual fermions has superior
convergence properties over standard diagrammatic techniques. The critical Neel
temperature of the mean-field solution is suppressed in the ladder
approximation, in accordance with quantum Monte-Carlo (QMC) results. An
illustration of how the approach captures and allows to distinguish short- and
long-range correlations is given.


title: Alpha_s from hadronic tau decay data

abstract:
  We discuss the extraction of alpha_s using isovector hadronic tau decay data
and sum rules constructed specifically to suppress contributions associated
with poorly known higher dimension condensates. We show, first, that problems
with the treatment of such contributions affect earlier related analyses and,
second, that these problems can be brought under good theoretical control
through the use of an alternate analysis strategy. Our results, run up to the
n_f=5 regime, correspond to alpha_s(M_Z^2)=0.1187(16), in excellent agreement
with the recently updated global fit to electroweak data at the Z scale and
other high-scale direct determinations.


title:
Square Complex Orthogonal Designs with no Zero Entry for any $2^m$
  Antennas

abstract:
  Space-time block codes from square complex orthogonal designs (SCOD) have
been extensively studied and most of the existing SCODs contain large number of
zeros. The zeros in the designs result in high peak-to-average power ratio and
also impose a severe constraint on hardware implementation of the code while
turning off some of the transmitting antennas whenever a zero is transmitted.
Recently, SCODs with no zero entry have been constructed for $2^a$ transmit
antennas whenever $a+1$ is a power of 2. Though there exists codes for 4 and 16
transmit antennas with no zero entry, there is no general method of
construction which gives codes for any number of transmit antennas. In this
paper, we construct SCODs for any power of 2 number of transmit antennas having
all its entries non-zero. Simulation results show that the codes constructed in
this paper outperform the existing codes for the same number of antennas under
peak power constraint while performing the same under average power constraint.


title:
Dynamical breaking of gauge symmetry in supersymmetric quantum
  electrodynamics in three-dimensional spacetime

abstract:
  The dynamical breaking of gauge symmetry in the supersymmetric quantum
electrodynamics in three-dimensional spacetime is studied at two-loop
approximation. At this level, the effective superpotential is evaluated in a
supersymmetric phase. At one-loop order, we observe a generation of the
Chern-Simons term due to a parity violating term present in the classical
action. At two-loop order, the scalar background superfield acquires a
nonvanishing vacuum expectation value, generating a mass term
$A^{\alpha}A_{\alpha}$ through Coleman-Weinberg mechanism. It is observed that
the mass of gauge superfield is predominantly an effect of the topological
Chern-Simons term.


title:
Heat kernel bounds, ancient $\kappa$ solutions and the Poincar\'e
  conjecture

abstract:
  We establish certain Gaussian type upper bound for the heat kernel of the
conjugate heat equation associated with 3 dimensional ancient $\kappa$
solutions to the Ricci flow.
  As an application, using the $W$ entropy associated with the heat kernel, we
give a different and shorter proof of Perelman's classification of backward
limits of these ancient solutions. The current paper together with \cite{Z:2}
and a different proof of universal noncollapsing due to Chen and Zhu
\cite{ChZ:1} lead to a simplified proof of the Poincar\'e conjecture without
using reduced distance and reduced volume.


title:
Uniqueness of contact Hamiltonians of topological strictly contact
  isotopies

abstract:
  We prove that for regular contact forms there exists a bijective
correspondence between the $C^0$ limits of sequences of smooth strictly contact
isotopies and the limits with respect to the contact distance of their
corresponding Hamiltonians.


title:
The example of a self-similar continuum which is not an attractor of any
  zipper

abstract:
  The article contains a construction of a self-similar dendryte which cannot
be the attractor of any self-similar zipper.


title: Gas and Stars in Galaxies - A Multi-Wavelength 3D Perspective

abstract:
  An overview of the ESO/Radionet workshop devoted to 3D optical/near-infrared
and sub-mm/radio observations of gas and stars in galaxies is presented. There
will be no published proceedings but presentations are available at
http://www.eso.org/sci/meetings/gal3D2008/program.html . The main aim of this
ESO/Radionet workshop was to bring together the optical/ near-IR and
sub-mm/radio communities working on three-dimensional (3D) extragalactic data.
The meeting was attended by more than 150 scientists. This article, due to
space limitations, provides a, necessarily biased, overview of the meeting.


title: Is the wind of the Oe star HD 155806 magnetically confined?

abstract:
  Oe stars are a subset of the O-type stars that exhibit emission lines from a
circumstellar disk. The recent detection of magnetic fields in some O-type
stars suggests a possible explanation for the stability of disk-like structures
around Oe stars. According to this hypothesis, the wind of the star is
channeled by a dipolar magnetic field producing a disc in the magnetic
equatorial plane. As a test of this model, we have obtained spectropolarimetric
observations of the hottest Galactic Oe star HD 155806. Here we discuss the
results and implications of those observations.


title:
Multiplicity Distribution of Secondary Hadrons at LHC Energy and Total
  Cross Sections of Hadron-Hadron Interactions

abstract:
  The multiple production processes of secondary hadrons in proton-antiproton
scattering are divided into three types. The first type is a shower of
secondary hadrons produced from gluon string decay, the second type is a shower
of secondary hadrons produced from two quark strings decay and the third is a
shower produced from three quark strings decay. At the same time there are only
two types for proton-proton scattering - shower from gluon string and shower
from two quark strings. These showers do not correspond to pomeron showers
originating from cuts of one, two, three, ... pomerons. Multiplicity
distribution in gluon string is Gaussian, in two and three quark strings it is
negative binomial. Gluon string weight in the multiplicity distribution is
determined by the constant contribution to total cross sections, the quark
strings weights - by the growing with energy contributions. The expected value
of proton-proton scattering total cross section and the multiplicity
distribution at energy 14 TeV are given


title: Van der Waerden's Theorem and Avoidability in Words

abstract:
  Pirillo and Varricchio, and independently, Halbeisen and Hungerbuhler
considered the following problem, open since 1994: Does there exist an infinite
word w over a finite subset of Z such that w contains no two consecutive blocks
of the same length and sum? We consider some variations on this problem in the
light of van der Waerden's theorem on arithmetic progressions.


title:
The Polish doughnuts revisited I. The angular momentum distribution and
  equipressure surfaces

abstract:
  We construct a new family of analytic models of black hole accretion disks in
dynamical equilibria. Our construction is based on assuming distributions of
angular momentum and entropy. For a particular choice of the distribution of
angular momentum, we calculate the shapes of equipressure surfaces. The
equipressure surfaces we find are similar to those in thick, slim and thin
disks, and to those in ADAFs.


title: The spin content of the proton

abstract:
  Considerable progress has been made in our knowledge of the spin distribution
within the proton. The recently measured limits on polarized gluons in the
proton suggest polarized gluons contribute very modestly to the proton spin. We
will show that a modern, relativistic and chirally symmetric description of the
nucleon structure naturally explain the current proton spin data. Most of the
"missing" spin is carried by confined quark and antiquarks' angular momentum.


title: Interplay between magnetism and superconductivity in Fe-pnictides

abstract:
  We consider phase transitions and potential co-existence of spin-density-wave
(SDW) magnetic order and extended s-wave ($s^+$) superconducting order within a
two-band itinerant model of iron pnictides, in which SDW magnetism and $s^+$
superconductivity are competing orders. We show that depending on parameters,
the transition between these two states is either first order, or involves an
intermediate phase in which the two orders co-exist. We demonstrate that such
co-existence is possible when SDW order is incommensurate.


title: On The Origin Of The Highest Redshift Gamma-Ray Bursts

abstract:
  GRB 080913 and GRB 090423 are the most distant gamma-ray bursts (GRBs) known
to-date, with spectroscopically determined redshifts of z=6.7 and z=8.1,
respectively. The detection of bursts at this early epoch of the Universe
significantly constrains the nature of GRBs and their progenitors. We perform
population synthesis studies of the formation and evolution of early stars, and
calculate the resulting formation rates of short and long-duration GRBs at high
redshift. The peak of the GRB rate from Population II stars occurs at z=7 for a
model with efficient/fast mixing of metals, while it is found at z=3 for an
inefficient/slow metallicity evolution model. We show that in the redshift
range 6<z<10 essentially all GRBs originate from Population II stars,
regardless of metallicity evolution model. These stars (having small, but
non-zero metallicity) are the most likely progenitors for both long GRBs
(collapsars) and short GRBs (NS-NS or BH-NS mergers) at this epoch. Although
the predicted intrinsic rates of long and short GRBs are similar at these high
redshifts, observational selection effects lead to higher (factor of 10)
observed rates for long GRBs. We conclude that the two recently observed high-z
GRB events are most likely long GRBs originating from Population II collapsars.


title:
The excitation of spiral density waves through turbulent fluctuations in
  accretion discs II: Numerical Simulations with MRI driven turbulence

abstract:
  We present fully three-dimensional local MRI simulations with the object of
studying the excitation of non-axisymmetric spiral density waves that are
observed to always be present in such simulations. They are potentially
important for affecting protoplanetary migration through the action of
associated stochastic gravitational forces and producing residual transport in
MHD inactive regions. The simulations we perform are with zero net flux and
produce mean activity levels of alpha ~ 0.005. We reveal the nature of the
mechanism responsible for the excitation of these waves by determining the time
dependent evolution of the Fourier transforms of the participating state
variables. The dominant waves are found to have no vertical structure and to be
excited during periodically repeating swings in which they change from leading
to trailing. The initial phase of the evolution of such a swing is found to be
in excellent agreement with that expected from the WKBJ theory developed in a
preceding paper by Heinemann & Papaloizou.
  We demonstrate that the important source terms causing excitation of the
waves are related to a quantity that reduces to the potential vorticity for
small perturbations from the background state with no vertical dependence. We
find that the root mean square density fluctuations associated with the waves
are positively correlated with both this quantity and the general level of
hydromagnetic turbulence. The mean angular momentum transport associated with
spiral density waves generated in our simulations is estimated to be a
significant fraction of that associated with the turbulent Reynolds stress.


title:
Kinematical Conformal Cosmology: fundamental parameters from
  astrophysical observations

abstract:
  We continue our presentation of an alternative cosmology based on conformal
gravity, following our kinematical approach introduced in a recent paper. In
line with the assumptions of our model, which proposes a closed-form expression
for the cosmic scale factor R(t), we first revise the Hubble and deceleration
parameters and also introduce modified cosmological distances, analyzing in
particular the case of the luminosity distance.
  Our kinematical conformal cosmology is then able to explain the anomalous
acceleration of the Pioneer spacecraft, as due to a local region of
gravitational blueshift. From the reported values of the Pioneer anomaly we
also compute the current value of our first fundamental parameter, gamma_{0} =
1.94 x 10^{-28} cm^{-1}, in line with the original estimate by P. Mannheim of
this quantity.
  Our second fundamental parameter, delta_{0} = 3.83 x 10^{-5}, interpreted as
the current value of a cosmological time variable, is derived from a detailed
fitting of type Ia Supernovae "gold-silver" data, producing Hubble plots of the
same quality of those obtained by standard cosmology, but without requiring any
dark matter or dark energy contribution.
  If further experiments will confirm the presence of an anomalous frequency
blueshift in the outer region of the Solar System, as described by our model,
kinematical conformal cosmology might become a viable alternative to standard
cosmological theories.


title:
Generalized Hammersley Process and Phase Transition for Activated Random
  Walk Models

abstract:
  * ACTIVATED RANDOM WALK MODEL * This is a conservative particle system on the
lattice, with a Markovian continuous-time evolution. Active particles perform
random walks without interaction, and they may as well change their state to
passive, then stopping to jump. When particles of both types occupy the same
site, they all become active. This model exhibits phase transition in the sense
that for low initial densities the system locally fixates and for high
densities it keeps active. Though extensively studied in the physics
literature, the matter of giving a mathematical proof of such phase transition
remained as an open problem for several years. In this work we identify some
variables that are sufficient to characterize fixation and at the same time are
stochastically monotone in the model's parameters. We employ an explicit
graphical representation in order to obtain the monotonicity. With this method
we prove that there is a unique phase transition for the one-dimensional
finite-range random walk. Joint with V. Sidoravicius.
  * BROKEN LINE PROCESS * We introduce the broken line process and derive some
of its properties. Its discrete version is presented first and a natural
generalization to the continuum is then proposed and studied. The broken lines
are related to the Young diagram and the Hammersley process and are useful for
computing last passage percolation values and finding maximal oriented paths.
For a class of passage time distributions there is a family of boundary
conditions that make the process stationary and reversible. One application is
a simple proof of the explicit law of large numbers for last passage
percolation with exponential and geometric distributions. Joint with V.
Sidoravicius, D. Surgailis, and M. E. Vares.


title:
Generation of entangled photon-pairs from a single quantum dot embedded
  in a planar photonic-crystal cavity

abstract:
  We present a formal theory of single quantum-dot coupling to a planar
photonic crystal that supports quasi-degenerate cavity modes, and use this
theory to describe, and optimize, entangled-photon-pair generation via the
biexciton-exciton cascade. In the generated photon pairs, either both photons
are spontaneously emitted from the dot, or one photon is emitted from the
biexciton spontaneously and the other is emitted via the leaky-cavity mode. In
the strong-coupling regime, the generated photon pairs can be maximally
entangled, in qualitative agreement with the simple dressed-state predictions
of Johne {\em et al.} [Phys. Rev. Lett. vol. 100, 240404 (2008)]. We derive
useful and physically-intuitive analytical formulas for the spectrum of the
emitted photon pairs in the presence of exciton and biexciton broadening, which
is necessary to connect to experiments, and demonstrate the clear failure of
using a dressed-state approach. We also present a method for calculating and
optimizing the entanglement between the emitted photons, which can account for
post-sample spectral filtering. Pronounced entanglement values of greater than
80% are demonstrated using experimentally achievable parameters, even without
spectral filtering.


title: Dynamical Simulations of the Planetary System HD69830

abstract:
  HD 69830 exhibits radial velocity variations attributed to three planets as
well as infrared emission attributed to a warm debris disk. Previous studies
have developed models for the planet migration and mass growth (Alibert et al.
2006) and the replenishment of warm grains (Wyatt et al. 2007). We perform
n-body integrations in order to explore the implications of these models for:
1) the excitation of planetary eccentricity, 2) the accretion and clearing of a
putative planetesimal disk, 3) the distribution of planetesimal orbits
following migration, and 4) the implications for the origin of the IR emission.
We find that: i) It is not possible to explain the observed planetary
eccentricities (e~0.1) purely as the result of planetary perturbations during
migration unless the planetary system is nearly face-on. ii) The rate of
accretion of planetesimals onto planets in our n-body simulations is
significantly different to that assumed in the semi-analytic models, suggesting
that one cannot successfully treat planetesimal accretion in the simplified
manner of Alibert et al. (2006). iii) Eccentricity damping of planetesimals
does not act as an insurmountable obstacle to the existence of an excited
eccentric disk: All simulations result in at least 25 Earth-masses of material
remaining bound in the region ~1-9 AU, even after all three planets have
migrated through the region. iv) Gas drag works to size-sort the planetesimals,
with the largest bodies preferentially occupying the highest eccentricity and
longest-lived orbits. Further work will be required to understand whether these
eccentricity distributions are high enough to explain the level of dust
emission observed despite mass loss via steady state collisional evolution.
[abridged]


title:
A Millimetre Survey of Starburst Dominated Ultraluminous Infrared
  Galaxies at z~2

abstract:
  We present millimetre observations of a sample of 12 high redshift
ultraluminous infrared galaxies (ULIRGs) in the Extended Growth Strip (EGS).
These objects were initially selected on the basis of their observed mid--IR
colours (0.0 < [3.6]-[4.5] < 0.4 and -0.7 < [3.6]-[8.0] < 0.5) to lie at high
redshift 1.5 < z < 3, and subsequent 20-38 micron mid-IR spectroscopy confirms
that they lie in a narrow redshift window centered on z=2. We detect 9/12 of
the objects in our sample at high significance (>3 sigma) with a mean
1200\micron flux of <F_1200> = 1.6+/-0.1 mJy. Our millimetre photometry,
combined with existing far-IR photometry from the Far-IR Deep Extragalactic
Legacy (FIDEL) Survey and accurate spectroscopic redshifts, places constraints
both sides of the thermal dust peak. This allows us to estimate the dust
properties, including the far--IR luminosity, dust temperature, and dust mass.
We find that our sample is similar to other high-z and intermediate-z ULIRGs,
and local systems, but has a different dust selection function than
submillimeter-selected galaxies. Finally, we use existing 20cm radio continuum
imaging to test the far-IR/radio correlation at high redshift. We find that our
sample is consistent with the local relation, implying little evolution.
Furthermore, this suggests that our sample selection method is efficient at
identifying ultraluminous, starburst--dominated systems within a very narrow
redshift range centered at z~2.


title: Collective Quartics and Dangerous Singlets in Little Higgs

abstract:
  Any extension of the standard model that aims to describe TeV-scale physics
without fine-tuning must have a radiatively-stable Higgs potential. In little
Higgs theories, radiative stability is achieved through so-called collective
symmetry breaking. In this letter, we focus on the necessary conditions for a
little Higgs to have a collective Higgs quartic coupling. In one-Higgs doublet
models, a collective quartic requires an electroweak triplet scalar. In
two-Higgs doublet models, a collective quartic requires a triplet or singlet
scalar. As a corollary of this study, we show that some little Higgs theories
have dangerous singlets, a pathology where collective symmetry breaking does
not suppress quadratically-divergent corrections to the Higgs mass.


title:
Constraints on Primordial Non-Gaussianity from a Needlet Analysis of the
  WMAP-5 Data

abstract:
  We look for a non-Gaussian signal in the WMAP 5-year temperature anisotropy
maps by performing a needlet-based data analysis. We use the foreground-reduced
maps obtained by the WMAP team through the optimal combination of the W, V and
Q channels, and perform realistic non-Gaussian simulations in order to
constrain the non-linear coupling parameter $\fnl$. We apply a third-order
estimator of the needlet coefficients skewness and compute the $\chi^2$
statistics of its distribution. We obtain $-80<\fnl<120$ at 95% confidence
level, which is consistent with a Gaussian distribution and comparable to
previous constraints on the non-linear coupling. We then develop an estimator
of $\fnl$ based on the same simulations and we find consistent constraints on
primordial non-Gaussianity. We finally compute the three point correlation
function in needlet space: the constraints on $\fnl$ improve to $-50<\fnl<110$
at 95% confidence level.


title: Radiative Feedback in Relic HII Regions at High-Redshift

abstract:
  UV radiation from early astrophysical sources could have a large impact on
subsequent star formation in nearby protogalaxies. Here we study the radiative
feedback from the first, short-lived stars using hydrodynamical simulations
with transient UV backgrounds (UVBs) and persistent Lyman-Werner backgrounds
(LWBs) of varying intensity. We extend our prior work in Mesinger et al.
(2006), by studying a more typical region whose proto-galaxies form at lower
redshifts, z~13-20, in the epoch likely preceding the bulk of reionization. We
confirm our previous results that feedback in the relic HII regions resulting
from such transient radiation, is itself transient. Feedback effects dwindle
away after ~30% of the Hubble time, and the same critical specific intensity of
J_UV~0.1 x 10^{-21} ergs/s/cm^2/Hz/sr separates positive and negative feedback
regimes. Additionally, we discover a second episode of eventual positive
feedback in halos which have not yet collapsed when their progenitor regions
were exposed to the transient UVB. This eventual positive feedback appears in
all runs, regardless of the strength of the UVB. However, this feedback regime
is very sensitive to the presence of Lyman-Werner radiation, and notable
effects disappear under fairly modest background intensities of J_LW>10^{-3} x
10^{-21} ergs/s/cm^2/Hz/sr. We conclude that UV radiative feedback in relic HII
regions, although a complicated process, seems unlikely to have a major impact
on the progress of cosmological reionization, provided that present estimates
of the lifetime and luminosity of a PopIII star are accurate. More likely is
that the build-up of the LWB ultimately governs the feedback strength until a
persistent UV background can be established. [abridged]


title:
The anisotropic redshift space galaxy correlation function: detection on
  the BAO Ring

abstract:
  In a series of papers we have recently studied the clustering of LRG galaxies
in the latest spectroscopic SDSS data release, which has 75000 LRG galaxies
sampling 1.1 Gpc^3/h^3 to z=0.47. Here we focus on detecting a local maxima
shaped as a circular ring in the bidimensional galaxy correlation function
\xi(pi,sigma), separated in perpendicular \sigma and line-of-sight \pi
distances. We find a significant detection of such a peak at r ~110 Mpc/h. The
overall shape and location of the ring is consistent with it originating from
the recombination-epoch baryon acoustic oscillations (BAO). This agreement
provides support for the current understanding of how large scale structure
forms in the universe. We study the significance of such feature using large
mock galaxy simulations to provide accurate errorbars.


title: A Highly Complete Spectroscopic Survey of the GOODS-N Field

abstract:
  We present a table of redshifts for 2907 galaxies and stars in the 145 square
arcmin HST ACS GOODS-North, making this the most spectroscopically complete
redshift sample obtained to date in a field of this size. We also include the
redshifts, where available, in a table containing just under 7000 galaxies from
the ACS area with K_s(AB)<24.5 measured from a deep K_s image obtained with
WIRCam on the CFHT, as well as in a table containing 1016 sources with
NUV(AB)<25 and 478 sources with FUV(AB)<25.5 (there is considerable overlap)
measured from the deep GALEX images in the ACS area. Finally, we include the
redshifts, where available, in a table containing the 1199 24 micron sources to
80 uJy measured from the wider-area Spitzer GOODS-North. The redshift
identifications are greater than 90% complete to magnitudes of F435W(AB)=24.5,
F850LP(AB)=23.3, and K_s(AB)=21.5 and to 24 micron fluxes of 250 uJy. An
extensive analysis of these data will appear in a parallel paper, but here we
determine how efficient color-selection techniques are at identifying
high-redshift galaxies and Active Galactic Nuclei. We also examine the
feasibility of doing tomography of the intergalactic medium with a 30 m
telescope.


title: Collapse and folding of pressurized rings in two dimensions

abstract:
  Hydrostatically pressurized circular rings confined to two dimensions (or
cylinders constrained to have only z-independent deformations) undergo Euler
type buckling when the outside pressure exceeds a critical value. We perform a
stability analysis of rings with arc-length dependent bending moduli and
determine how weakened bending modulus segments affect the buckling critical
pressure. Rings with a 4-fold symmetric modulation are particularly susceptible
to collapse. In addition we study the initial post-buckling stages of the
pressurized rings to determine possible ring folding patterns.


title: Statistical Properties of Gamma-Ray Burst Polarization

abstract:
  The emission mechanism and the origin and structure of magnetic fields in
gamma-ray burst (GRB) jets are among the most important open questions
concerning the nature of the central engine of GRBs. In spite of extensive
observational efforts, these questions remain to be answered and are difficult
or even impossible to infer with the spectral and lightcurve information
currently collected. Polarization measurements will lead to unambiguous answers
to several of these questions. Recent developments in X-ray and gamma-ray
polarimetry techniques have demonstrated a significant increase in sensitivity
enabling several new mission concepts, e.g. POET (Polarimeters for Energetic
Transients), providing wide field of view and broadband polarimetry
measurements. If launched, missions of this kind would finally provide
definitive measurements of GRB polarizations. We perform Monte Carlo
simulations to derive the distribution of GRB polarizations in three emission
models; the synchrotron model with a globally ordered magnetic field (SO
model), the synchrotron model with a locally random magnetic field (SR model),
and the Compton drag model (CD model). The results show that POET, or other
polarimeters with similar capabilities, can constrain the GRB emission models
by using the statistical properties of GRB polarizations. In particular, the
ratio of the number of GRBs for which the polarization degrees can be measured
to the number of GRBs that are detected (N_m/N_d) and the distributions of the
polarization degrees (Pi) can be used as the criteria. If N_m/N_d > 30% and Pi
is clustered between 0.2 and 0.7, the SO model will be favored. If instead
N_m/N_d < 15%, then the SR or CD model will be favored. If several events with
Pi > 0.8 are observed, then the CD model will be favored.


title:
The determination of alpha_s(M_z) from perturbative analyses of
  short-distance-sensitive lattice QCD observables revisited

abstract:
  The determination of alpha_s(M_Z) via perturbative analyses of
short-distance-sensitive lattice observables is revisited, incorporating new
lattice data and performing a modified version of the original analysis. The
analysis employs two high-intrinsic-scale observables, log (W_11) and
log(W_12), and one lower-intrinsic-scale observable, log(W_12/u_0^6). We find
good consistency among the values extracted using the different observables and
a final result, alpha_s(M_Z)=0.1192(11), in excellent agreement with various
recent non-lattice determinations, as well as with the results of a similar,
but not identical, re-analysis by the HPQCD collaboration. The relation between
the two re-analyses is discussed, focussing on the complementarity of the two
approaches.


title: Two-Qubit State Tomography using a Joint Dispersive Read-Out

abstract:
  Quantum state tomography is an important tool in quantum information science
for complete characterization of multi-qubit states and their correlations.
Here we report a method to perform a joint simultaneous read-out of two
superconducting qubits dispersively coupled to the same mode of a microwave
transmission line resonator. The non-linear dependence of the resonator
transmission on the qubit state dependent cavity frequency allows us to extract
the full two-qubit correlations without the need for single shot read-out of
individual qubits. We employ standard tomographic techniques to reconstruct the
density matrix of two-qubit quantum states.


title: Characterization of linear groups whose reduced C*-algebras are simple

abstract:
  The reduced C*-algebra of a countable linear group G is shown to be simple if
and only if G has no nontrivial normal amenable subgroups. Moreover, these
conditions are shown to be equivalent to the uniqueness of tracial state on the
aforementioned C*-algebra.


title: Hydrodynamic orienting of asymmetric microobjects under gravity

abstract:
  It is shown that nonsymmetric microobjects orient while settling under
gravity in a viscous fluid. To analyze this process, a simple shape is chosen:
a non-deformable `chain'. The chain consists of two straight arms, made of
touching solid spheres. In the absence of external torques, the spheres are
free to spin along the arms. The motion of the chain is evaluated by solving
the Stokes equations with the use of the multipole method. It is demonstrated
that the spinning beads speed up sedimentation by a small amount, and increase
the orientation rate significantly in comparison to the corresponding rigid
chain. It is shown that chains orient towards the V-shaped stable stationary
configuration. In contrast, rods and star-shaped microobjects do not rotate.
The hydrodynamic orienting is relevant for efficient swimming of non-symmetric
microobjects, and for sedimenting suspensions.


title:
Heterotic Strings on Generalized Calabi-Yau Manifolds and Kaehler Moduli
  Stabilization

abstract:
  Compactifications of heterotic string theory on Generalized Calabi-Yau
manifolds have been expected to give the same type of flexibility that type IIB
compactifications on Calabi-Yau orientifolds have. In this note we generalize
the work done on half-flat manifolds by other authors, to show how flux
quantization occurs in the general case, by starting with a basis of harmonic
forms and then extending it. However it turns out that only the axions
associated with the non-harmonic directions in the space of Kaehler moduli, can
be stabilized by the geometric (torsion) terms. Also we argue that there are no
supersymmetric extrema of the potential when the second (and fourth) cohomology
groups on the manifold are non-trivial. We suggest that threshold corrections
to the classical gauge coupling function could solve these problems.


title: Radion Mediated Flavor Changing Neutral Currents

abstract:
  In the context of a warped extra-dimension with Standard Model fields in the
bulk, we obtain the general flavor structure of the Radion couplings to
fermions and show that the result is independent on the particular nature of
the Higgs mechanism (bulk or brane localized). These couplings will be
generically misaligned with respect to the fermion mass matrix when the fermion
bulk mass parameters are not all degenerate. When the Radion is light enough,
the generic size of these tree-level flavor changing couplings will be strongly
constrained by the experimental bounds on $\Delta F=2$ processes. At the LHC
the possibility of a heavier Radion decaying into top and charm quarks is then
considered as a promising signal to probe the flavor structure of both the
Radion sector and the whole scenario.


title: Constraining the energy budget of GRB 080721

abstract:
  We follow the bright, highly energetic afterglow of Swift-discovered GRB
080721 at z=2.591 out to 36 days or 3e6 s since the trigger in the optical and
X-ray bands. We do not detect a break in the late-time light curve inferring a
limit on the opening angle of theta_j >= 7.3 deg and setting tight constraints
on the total energy budget of the burst of E_gamma >= 9.9e51 erg within the
fireball model. To obey the fireball model closure relations the GRB jet must
be expanding into a homogeneous surrounding medium and likely lies behind a
significant column of dust. The energy constraint we derive can be used as
observational input for models of the progenitors of long gamma-ray bursts: we
discuss how such high collimation-corrected energies could be accommodated with
certain parameters of the standard massive star core-collapse models. We can,
however, most probably rule out a magnetar progenitor for this GRB which would
require 100% efficiency to reach the observed total energy.


title: Monochromatic plane-fronted waves in conformal gravity are pure gauge

abstract:
  We consider plane-fronted, monochromatic gravitational waves on a Minkowski
background, in a conformally invariant theory of general relativity. By this we
mean waves of the form: $g_{\mu\nu}=\eta_{\mu\nu}+\epsilon_{\mu\nu}F(k\cdotx)$,
where $\epsilon_{\mu\nu}$ is a constant polarization tensor, and $k_\mu$ is a
lightlike vector. We also assume the coordinate gauge condition
$|g|-1/4\partial_\tau(|g|1/4g^{\sigma\tau})=0$ which is the conformal analog of
the harmonic gauge condition
$g^{\mu\nu}\Gamma_{\mu\nu}^\sigma=-|g|-1/2\partial_\tau(|g|1/2g^{\sigma\tau})=0,
where $\det[g_{\mu\nu}]\equivg$. Requiring additionally the conformal gauge
condition $g=-1$ surprisingly implies that the waves are both transverse and
traceless. Although the ansatz for the metric is eminently reasonable when
considering perturbative gravitational waves, we show that the metric is
reducible to the metric of Minkowski space-time via a sequence of coordinate
transformations which respect the gauge conditions, without any perturbative
approximation that \in{\mu}{\nu} be small. This implies that we have, in fact,
exact plane-wave solutions; however, they are simply coordinate/conformal
artifacts. As a consequence, they carry no energy. Our result does not imply
that conformal gravity does not have gravitational wave phenomena. A different,
more generalized ansatz for the deviation, taking into account the fourth-order
nature of the field equation, which has the form
$g_{\mu\nu}=\eta_{\mu\nu}+B_{\mu\nu}(n\cdotx)G(k\cdotx)$, indeed yields waves
which carry energy and momentum [P.D. Mannheim, Gen. Relativ. Gravit. 43, 703
(2010)]. It is just surprising that transverse, traceless, plane-fronted
gravitational waves, those that would be used in any standard, perturbative,
quantum analysis of the theory, simply do not exist.


title:
Defect Formation Energies without the Band-Gap Problem: Combining DFT
  and GW for the Silicon Self-Interstitial

abstract:
  We present an improved method to calculate defect formation energies that
overcomes the band-gap problem of Kohn-Sham density-functional theory (DFT) and
reduces the self-interaction error of the local-density approximation (LDA) to
DFT. We demonstrate for the silicon self-interstitial that combining LDA with
quasiparticle energy calculations in the G0W0 approach increases the defect
formation energy of the neutral charge state by ~1.1 eV, which is in good
agreement with diffusion Monte Carlo calculations (E. R. Batista et al. Phys.
Rev. B 74, 121102(R) (2006), W.-K. Leung et al. Phys. Rev. Lett. 83, 2351
(1999)). Moreover, the G0W0-corrected charge transition levels agree well with
recent measurements.


title: Howes et al. Reply

abstract:
  Howes et al. Reply to Comment on "Kinetic Simulations of Magnetized
Turbulence in Astrophysical Plasmas" arXiv:0711.4355


title:
Calculation of Topological Charge of Real Finite-Gap sine-Gordon
  solutions using Theta-functional formulae

abstract:
  The most basic characteristic of x-quasiperiodic solutions u(x,t) of the
sine-Gordon equation u_{tt}-u_{xx}+\sin u=0 is the topological charge density
denoted $\bar n$. The real finite-gap solutions u(x,t) are expressed in terms
of the Riemann theta-functions of a non-singular hyperelliptic curve $\Gamma$
and a positive generic divisor D of degree g on $\Gamma$, where the spectral
data $(\Gamma, D)$ must satisfy some reality conditions. The problem addressed
in note is: to calculate $\bar n$ directly from the theta-functional
expressions for the solution u(x,t). The problem is solved here by introducing
what we call the multiscale or elliptic limit of real finite-gap sine-Gordon
solutions. We deform the spectral curve to a singular curve, for which the
calculation of topological charges reduces to two special easier cases.


title: Intermittency and Thermalization in Turbulence

abstract:
  A dissipation rate, which grows faster than any power of the wave number in
Fourier space, may be scaled to lead a hydrodynamic system {\it actually} or
{\it potentially} converge to its Galerkin truncation. Actual convergence we
name for the asymptotic truncation at a finite wavenumber $k_G$ above which
modes have no dynamics; and, we define potential convergence for the truncation
at $k_G$ which, however, grows without bound. Both types of convergence can be
obtained with the dissipation rate $\mu[cosh(k/k_c)-1]$ who behaves as $k^2$
(newtonian) and $\exp\{k/k_c\}$ for small and large $k/k_c$ respectively.
Competition physics of cascade, thermalization and dissipation are discussed
with numerical Navier-Stokes turbulence, emphasizing on the intermittency
growth.


title:
Analytical Solutions for Radiative Transfer: Implications for Giant
  Planet Formation by Disk Instability

abstract:
  The disk instability mechanism for giant planet formation is based on the
formation of clumps in a marginally-gravitationally unstable protoplanetary
disk, which must lose thermal energy through a combination of convection and
radiative cooling if they are to survive and contract to become giant
protoplanets. While there is good observational support for forming at least
some giant planets by disk instability, the mechanism has become theoretically
contentious, with different three dimensional radiative hydrodynamics codes
often yielding different results. Rigorous code testing is required to make
further progress. Here we present two new analytical solutions for radiative
transfer in spherical coordinates, suitable for testing the code employed in
all of the Boss disk instability calculations. The testing shows that the Boss
code radiative transfer routines do an excellent job of relaxing to and
maintaining the analytical results for the radial temperature and radiative
flux profiles for a spherical cloud with high or moderate optical depths,
including the transition from optically thick to optically thin regions. These
radial test results are independent of whether the Eddington approximation,
diffusion approximation, or flux-limited diffusion approximation routines are
employed. The Boss code does an equally excellent job of relaxing to and
maintaining the analytical results for the vertical (theta) temperature and
radiative flux profiles for a disk with a height proportional to the radial
distance. These tests strongly support the disk instability mechanism for
forming giant planets.


title: Universal high-frequency transport in perfect photonic crystals

abstract:
  The light scattering in the periodic dielectric cylinder array is studied. We
analytically calculate the diffusive-ballistic transport crossover and find the
weak localization superimposing on it.
  Possible experimental observations are analyzed.


title: Pullback of varieties by finite maps

abstract:
  We study the local geometry of the pullback of a variety via a finite
holomorphic map. In particular, we are looking for properties of $V =
F^{-1}(W)$ such that if $V$ has the property $A$, then $W$ must have the
property $A$. We show that $A$ can be the property of normality or
prefactoriality. We also show that $A$ can be the property of smoothness, under
extra assumptions.


title: Isolated points in the space of left orderings of a group

abstract:
  Let G be a left orderable group and LO(G) the space of all left orderings. We
investigate the circumstances under which a left ordering < of G can correspond
to an isolated point in LO(G), in particular we extend known results to cover
the case of uncountable groups. With minor technical restrictions on the group
G, we also find that no dense left ordering is isolated in LO(G), and that the
closure of the set of all dense left orderings of G yields a dense G-delta set
within a Cantor set of left orderings in LO(G). Lastly, we show that certain
conditions on a discrete left ordering of G can guarantee that it is not
isolated in LO(G), and we illustrate these ideas using the Dehornoy ordering of
the braid groups.


title: Diffractive and Exclusive (Higgs?) Production from CDF to LHC

abstract:
  The diffractive program of the CDF Collaboration at the Fermilab Tevatron
p-pbar collider is reviewed with emphasis on recent results from Run II at a
c.m.s. energy of 1.96 TeV. Results are presented on the x-Bjorken and Q^2
dependence of the diffractive structure function obtained from di-jet
production, on the slope parameter of the t-distribution of diffractive events
as a function of Q^2 in the range 1 GeV^2<Q^2<10^4 GeV^2, and on cross sections
for exclusive di-jet, e+e-, and di-photon production. The exclusive di-jet and
di-photon production rates are used to check theoretical estimates of exclusive
Higgs boson production at the Large Hadron Collider. Other data on soft and
hard diffraction from p-ppbar collisions, and also data from diffractive deep
inelastic scattering are presented and interpreted in the RENORM
phenomenological model, in which cross sections are obtained from the
underlying inclusive parton distribution function of the nucleon and QCD color
factors.


title: Geo-Neutrinos

abstract:
  This paper briefly reviews recent developments in the field of geo-neutrinos.
It describes current and future detection projects, discusses modeling
projects, suggests an observational program, and visits geo-reactor hypotheses.


title: Not each sequential effect algebra is sharply dominating

abstract:
  Let $E$ be an effect algebra and $E_S$ be the set of all sharp elements of
$E$. $E$ is said to be sharply dominating if for each $a\in E$ there exists a
smallest element $\widehat{a}\in E_s$ such that $a\leq \widehat{a}$. In 2002,
Professors Gudder and Greechie proved that each $\sigma$-sequential effect
algebra is sharply dominating. In 2005, Professor Gudder presented 25 open
problems in International Journal of Theoretical Physics, Vol. 44, 2199-2205,
the 3th problem asked: Is each sequential effect algebra sharply dominating?
Now, we construct an example to answer the problem negatively.


title:
Characterization of an entangled system of two superconducting qubits
  using a multiplexed capacitance readout

abstract:
  We characterize a pair of Cooper-pair boxes coupled with a fixed capacitor
using spectroscopy and measurements of the ground-state quantum capacitance. We
use the extracted parameters to estimate the concurrence, or degree of
entanglement between the two qubits. We also present a thorough demonstration
of a multiplexed quantum capacitance measurement technique, which is in
principle scalable to a large array of superconducting qubits.


title: Diffusive Charge Transport in Graphene on SiO2

abstract:
  We review our recent work on the physical mechanisms limiting the mobility of
graphene on SiO2. We have used intentional addition of charged scattering
impurities and systematic variation of the dielectric environment to
differentiate the effects of charged impurities and short-range scatterers. The
results show that charged impurities indeed lead to a conductivity linear in
density in graphene, with a scattering magnitude that agrees quantitatively
with theoretical estimates [1]; increased dielectric screening reduces
scattering from charged impurities, but increases scattering from short-range
scatterers [2]. We evaluate the effects of the corrugations (ripples) of
graphene on SiO2 on transport by measuring the height-height correlation
function. The results show that the corrugations cannot mimic long-range
(charged impurity) scattering effects, and have too small an
amplitude-to-wavelength ratio to significantly affect the observed mobility via
short-range scattering [3, 4]. Temperature-dependent measurements show that
longitudinal acoustic phonons in graphene produce a resistivity linear in
temperature and independent of carrier density [5]; at higher temperatures,
polar optical phonons of the SiO2 substrate give rise to an activated, carrier
density-dependent resistivity [5]. Together the results paint a complete
picture of charge carrier transport in graphene on SiO2 in the diffusive
regime.


title: Universal deformation rings for the symmetric group S_4

abstract:
  Let k be an algebraically closed field of characteristic 2, and let W be the
ring of infinite Witt vectors over k. Let S_4 denote the symmetric group on 4
letters. We determine the universal deformation ring R(S_4,V) for every
kS_4-module V which has stable endomorphism ring k and show that R(S_4,V) is
isomorphic to either k, or W[t]/(t^2,2t), or the group ring W[Z/2]. This gives
a positive answer in this case to a question raised by the first author and
Chinburg whether the universal deformation ring of a representation of a finite
group with stable endomorphism ring k is always isomorphic to a subquotient
ring of the group ring over W of a defect group of the modular block associated
to the representation.


title:
Fluctuation theory and exit systems for positive self-similar Markov
  processes

abstract:
  For a positive self-similar Markov process, X, we construct a local time for
the random set, $\Theta$, of times where the process reaches its past supremum.
Using this local time we describe an exit system for the excursions of X out of
its past supremum. Next, we define and study the ladder process (R,H)
associated to a positive self-similar Markov process X, namely a bivariate
Markov process with a scaling property whose coordinates are the right inverse
of the local time of the random set $\Theta$ and the process X sampled on the
local time scale. The process (R,H) is described in terms of a ladder process
linked to the L\'{e}vy process associated to X via Lamperti's transformation.
In the case where X never hits 0, and the upward ladder height process is not
arithmetic and has finite mean, we prove the finite-dimensional convergence of
(R,H) as the starting point of X tends to 0. Finally, we use these results to
provide an alternative proof to the weak convergence of X as the starting point
tends to 0. Our approach allows us to address two issues that remained open in
Caballero and Chaumont [Ann. Probab. 34 (2006) 1012-1034], namely, how to
remove a redundant hypothesis and how to provide a formula for the entrance law
of X in the case where the underlying L\'{e}vy process oscillates.


title:
Enhanced heat transport by turbulent two-phase Rayleigh-B\'enard
  convection

abstract:
  We report measurements of turbulent heat-transport in samples of ethane
(C$_2$H$_6$) heated from below while the applied temperature difference $\Delta
T$ straddled the liquid-vapor co-existance curve $T_\phi(P)$. When the sample
top temperature $T_t$ decreased below $T_\phi$, droplet condensation occurred
and the latent heat of vaporization $H$ provided an additional heat-transport
mechanism.The effective conductivity $\lambda_{eff}$ increased linearly with
decreasing $T_t$, and reached a maximum value $\lambda_{eff}^*$ that was an
order of magnitude larger than the single-phase $\lambda_{eff}$. As $P$
approached the critical pressure, $\lambda_{eff}^*$ increased dramatically even
though $H$ vanished. We attribute this phenomenon to an enhanced
droplet-nucleation rate as the critical point is approached.


title: Dynamics of a self-gravitating neutron source

abstract:
  We examine the dynamics of a self--gravitating magnetized neutron gas as a
source of a Bianchi I spacetime described by the Kasner metric. The set of
Einstein-Maxwell field equations can be expressed as a dynamical system in a
4-dimensional phase space. Numerical solutions of this system reveal the
emergence of a point--like singularity as the final evolution state for a large
class of physically motivated initial conditions. Besides the theoretical
interest of studying this source in a fully general relativistic context, the
resulting idealized model could be helpful in understanding the collapse of
local volume elements of a neutron gas in the critical conditions that would
prevail in the center of a compact object.


title: Spin-Transfer Torque in Helical Spin-Density Waves

abstract:
  The current driven magnetisation dynamics of a helical spin-density wave is
investigated. Expressions for calculating the spin-transfer torque of real
systems from first principles density functional theory are presented. These
expressions are used for calculating the spin-transfer torque for the spin
spirals of Er and fcc Fe at two different lattice volumes. It is shown that the
calculated torque induces a rigid rotation of the order parameter with respect
to the spin spiral axis. The torque is found to depend on the wave vector of
the spin spiral and the spin-polarisation of the Fermi surface states. The
resulting dynamics of the spin spiral is also discussed.


title:
Post Common Envelope Binaries from SDSS. V: Four eclipsing white dwarf
  main sequence binaries

abstract:
  We identify SDSS011009.09+132616.1, SDSS030308.35+005444.1,
SDSS143547.87+373338.5 and SDSS154846.00+405728.8 as four eclipsing white dwarf
plus main sequence (WDMS) binaries from the Sloan Digital Sky Survey, and
report on follow-up observations of these systems. Orbital periods and
ephemerides have been established from multi-season photometry. SDSS1435+3733,
with Porb=3h has the shortest orbital period of all known eclipsing WDMS
binaries. Time-resolved spectroscopic observations have been obtained and the
radial velocities of the secondary stars in all four systems were measured. A
spectral decomposition/fitting technique was then employed to determine the
white dwarf effective temperatures and surface gravities, as well as the
spectral types of the companion stars. We used a light curve modeling code to
further constrain the masses and radii of the components in all systems. All
three DA white dwarfs have masses of Mwd~0.4-0.6Msun, in line with the
expectations from close binary evolution. The DC white dwarf in SDSS0303+0054
has a mass of Mwd>0.85Msun, making it unusually massive for a post-common
envelope system. Our new additions raise the number of known eclipsing WDMS
binaries to fourteen, and we find that the average white dwarf mass in this
sample is <Mwd>=0.57+/-0.16Msun, only slightly lower than the average mass of
single white dwarfs. The majority of all eclipsing WDMS binaries contain
low-mass (<0.6Msun) secondary stars, and will eventually provide valuable
observational input for the calibration of the mass-radius relations of
low-mass main sequence stars and of white dwarfs.


title: Diffraction with CDF II at the Tevatron

abstract:
  Results on diffraction from the Fermilab Tevatron collider obtained by the
CDF II Collaboration using data from proton-antiproton collisions at a c.m.s.
energy of 1.96 TeV are reviewed and compared with theoretical expectations.
Implications for predictions of exclusive Higgs boson production rates at the
Large Hadron Collider are discussed.


title:
A Novel Temperature-Induced Magnetization Transition in Pt/Co/Pt
  Sandwiches

abstract:
  It is found in the Pt/Co/Pt(111) sandwiches that perpendicular magnetic
anisotropy weakens associated with the dramatic magnetization enhancement as
the temperature decreases below a critical temperature, T_cri, which increases
with the Pt overlayer thickness t_Pt. For the sandwich with enough thick Pt
overlayer, it trends to an unusual state with weak perpendicular magnetic
anisotropy in the absence of obvious easy direction behavior at low
temperature. It suggests that Pt is more significantly polarized in the film
with thicker Pt overlayer. The results reveal the strong influence of both
thick nonmagnetic coverage and temperature on the electronic structure of the
Pt/Co/Pt(111) sandwich.


title:
Stationary subsonic boundary layer in the regions of local heating of
  surface

abstract:
  The problem of disturbed flow in the laminar boundary layer is investigated
when a heating element is located on the surface of the body. The flow is
supposed to be laminar one. It is shown that the problem may be solved in terms
of free interaction theory. The solution of linear flat problem is constructed.
The results of asymptotic analysis are also presented.


title:
Spatial and temporal characterization of a Bessel beam produced using a
  conical mirror

abstract:
  We experimentally analyze a Bessel beam produced with a conical mirror,
paying particular attention to its superluminal and diffraction-free
properties. We spatially characterized the beam in the radial and on-axis
dimensions, and verified that the central peak does not spread over a
propagation distance of 73 cm. In addition, we measured the superluminal phase
and group velocities of the beam in free space. Both spatial and temporal
measurements show good agreement with the theoretical predictions.


title: Shock Speed, Cosmic Ray Pressure, and Gas Temperature in the Cygnus Loop

abstract:
  Upper limits on the shock speeds in supernova remnants can be combined with
post-shock temperatures to obtain upper limits on the ratio of cosmic ray to
gas pressure (P_CR / P_G) behind the shocks. We constrain shock speeds from
proper motions and distance estimates, and we derive temperatures from X-ray
spectra. The shock waves are observed as faint H-alpha filaments stretching
around the Cygnus Loop supernova remnant in two epochs of the Palomar
Observatory Sky Survey (POSS) separated by 39.1 years. We measured proper
motions of 18 non-radiative filaments and derived shock velocity limits based
on a limit to the Cygnus Loop distance of 576 +/- 61 pc given by Blair et al.
for a background star. The PSPC instrument on-board ROSAT observed the X-ray
emission of the post-shock gas along the perimeter of the Cygnus Loop, and we
measure post-shock electron temperature from spectral fits. Proper motions
range from 2.7 arcseconds to 5.4 arcseconds over the POSS epochs and post-shock
temperatures range from kT ~ 100-200 eV. Our analysis suggests a cosmic ray to
post-shock gas pressure consistent with zero, and in some positions P_CR is
formally smaller than zero. We conclude that the distance to the Cygnus Loop is
close to the upper limit given by the distance to the background star and that
either the electron temperatures are lower than those measured from ROSAT PSPC
X-ray spectral fits or an additional heat input for the electrons, possibly due
to thermal conduction, is required.


title:
Accretion onto Intermediate-Mass Black Holes in Dense Protogalactic
  Clouds

abstract:
  We present the first results from two-dimensional simulations of
radiatively-efficient accretion of metal-free gas onto intermediate-mass black
holes. We fix the shape of the spectral energy distribution of the radiation
produced near the event horizon and study the structure of the irradiated
low-angular-momentum accretion flow over three orders of magnitude in radius
from the black hole, 10^{14}-10^{17} cm for a 100 M_sun black hole. The
luminosity of the central source is made to be proportional to the rate at
which gas accretes across the inner boundary, which we set just inside the
sonic radius. We find that photoionization heating and radiation pressure
modify the structure of the flow. When the ambient gas density is 10^7 cm^{-3},
accretion is intermittent and on average reduced to 32% of the
Eddington-limited rate, two orders of magnitude below the "Bondi" rate
evaluated ignoring radiation, in agreement with simplified theoretical models.
Even if the vicinity of the black hole is supplied with high density gas,
accretion is rendered inefficient through heating and radiation pressure.


title:
A measurement of the Q^2, W and t dependences of deeply virtual Compton
  scattering at HERA

abstract:
  Deeply virtual Compton scattering has been measured in e^+p collisions at
HERA with the ZEUS detector using an integrated luminosity of 61.1 pb^-1. Cross
sections are presented as a function of the photon virtuality, Q^2, and
photon-proton centre-of-mass energy, W, for a wide region of the phase space,
Q^2>~1.5 GeV^2 and 40<W<170 GeV. A subsample of events in which the scattered
proton is measured in the leading proton spectrometer, corresponding to an
integrated luminosity of 31.3 pb^-1, is used for the first direct measurement
of the differential cross section as a function of t, where t is the square of
the four-momentum transfer at the proton vertex.


title:
Strongly Multiplicative and 3-Multiplicative Linear Secret Sharing
  Schemes

abstract:
  Strongly multiplicative linear secret sharing schemes (LSSS) have been a
powerful tool for constructing secure multiparty computation protocols.
However, it remains open whether or not there exist efficient constructions of
strongly multiplicative LSSS from general LSSS. In this paper, we propose the
new concept of a 3-multiplicative LSSS, and establish its relationship with
strongly multiplicative LSSS. More precisely, we show that any 3-multiplicative
LSSS is a strongly multiplicative LSSS, but the converse is not true; and that
any strongly multiplicative LSSS can be efficiently converted into a
3-multiplicative LSSS. Furthermore, we apply 3-multiplicative LSSS to the
computation of unbounded fan-in multiplication, which reduces its round
complexity to four (from five of the previous protocol based on strongly
multiplicative LSSS). We also give two constructions of 3-multiplicative LSSS
from Reed-Muller codes and algebraic geometric codes. We believe that the
construction and verification of 3-multiplicative LSSS are easier than those of
strongly multiplicative LSSS. This presents a step forward in settling the open
problem of efficient constructions of strongly multiplicative LSSS from general
LSSS.


title: Derived Mackey functors

abstract:
  For a finite group $G$, the so-called $G$-Mackey functors form an abelian
category $M(G)$ that has many applications in the study of $G$-equivariant
stable homotopy. One would expect that the derived category $D(M(G))$ would be
similarly important as the "homological" counterpart of the $G$-equivariant
stable homotopy category. It turns out that this is not so -- $D(M(G))$ is
pathological in many respects. We propose and study a replacement for
$D(M(G))$, a certain triangulated category $DM(G)$ of "derived Mackey functors"
that contains $M(G)$ but is different from $D(M(G))$. We show that standard
features of the $G$-equivariant stable homotopy category such as the fixed
points functors of two types have exact analogs for the category $DM(G)$.


title: Approach to Thermal Equilibrium in the Caldeira-Leggett Model

abstract:
  We provide an explicit analytical calculation that shows the asymptotic
approach of the one dimensional Caldeira-Leggett model to thermal equilibrium
in the high temperature and weak coupling limit. We investigate a free particle
and a harmonic oscillator system, using both the Lindblad and the non-Lindblad
type master equations for each case, and show that thermal equilibrium is
reached exactly for the free particle and aproximately for the harmonic
oscillator, irrespective of the initial preparation of the system. We also
generalize our calculation to higher dimensions.


title: Beyond eta/s = 1/4pi

abstract:
  We use low-energy effective description of gauge theory/string theory duality
to argue that the Kovtun-Son-Starinets viscosity bound is generically violated
in superconformal gauge theories with non-equal central charges $c\ne a$. We
present new examples (of string theory constructions and of gauge theories)
where the bound is violated in a controllable setting. We consider the
comparison of results from AdS/CFT calculations to the QCD plasma in the
context of this discussion.


title:
On Group bijections $\phi $ with $\phi(B)=A$ and $\forall a\in B,
  a\phi(a) \notin A$

abstract:
  A {\em Wakeford pairing} from $S$ onto $T$ is a bijection $\phi : S \to T$
such that $x\phi(x)\notin T,$ for every $x\in S.$ The number of such pairings
will be denoted by $\mu(S,T)$.
  Let $A$ and $ B$ be finite subsets of a group $G$ with $1\notin B$ and
$|A|=|B|.$ Also assume that the order of every element of $B$ is $\ge |B|$.
Extending results due to Losonczy and Eliahou-Lecouvey, we show that
$\mu(B,A)\neq 0.$ Moreover we show that $\mu(B,A)\ge \min
\{\frac{||B|+1}{3},\frac{|B|(q-|B|-1)}{2q-|B|-4}\},$ unless there is $a\in A$
such that $|Aa^{-1}\cap B|=|B|-1$ or $Aa^{-1}$ is a progression. In particular,
either $\mu(B,B) \ge \min \{\frac{||B|+1}{3},\frac{|B|(q-|B|-1)}{2q-|B|-4}\},$
or for some $a\in B,$ $Ba^{-1}$ is a progression.


title: Continuous self-similar evaporation of a rotating cosmic string loop

abstract:
  A solution of the linearized Einstein and Nambu-Goto equations is constructed
which describes the evaporation of a certain type of rotating cosmic string -
the Allen-Casper-Ottewill loop - under the action of its own self-gravity. The
solution evaporates self-similarly, and radiates away all its mass-energy and
momentum in a finite time. Furthermore, the corresponding weak-field metric can
be matched to a remnant Minkowski spacetime at all points on the future light
cone of the final evaporation point of the loop.


title:
Quantum Non-Magnetic state near Metal-Insulator Transition - a Possible
  Candidate of Spin Liquid State

abstract:
  In this paper, based on the formulation of an O(3) non-linear sigma model, we
study the two-dimensional Pi-flux Hubbard model at half-filling. A quantum
non-magnetic insulator is explored near the metal-insulator transition that may
be a possible candidate of the spin liquid state. Such quantum non-magnetic
insulator on square lattice is not induced by frustrations. Instead, it
originates from quantum spin fluctuations with relatively small effective spin
moments. In the strong-coupling limit, our results of the spin velocity and
spin order parameter agree with results obtained from earlier calculations.


title:
Magnetic Fields in Paradigms of Planetary Nebulae and Related MHD
  Frontiers

abstract:
  Many, if not all, post AGB stellar systems swiftly transition from a
spherical to a powerful aspherical pre-planetary nebula (pPNE) outflow phase
before waning into a PNe. The pPNe outflows require engine rotational energy
and a mechanism to extract this energy into collimated outflows. Just radiation
and rotation are insufficient but a symbiosis between rotation, differential
rotation and large scale magnetic fields remains promising. Present
observational evidence for magnetic fields in evolved stars is suggestive of
dynamically important magnetic fields, but both theory and observation are rife
with research opportunity. I discuss how magnetohydrodynamic outflows might
arise in pPNe and PNe and distinguish different between approaches that address
shaping vs. those that address both launch and shaping. Scenarios involving
dynamos in single stars, binary driven dynamos, or accretion engines cannot be
ruled out. One appealing paradigm involves accretion onto the primary post-AGB
white dwarf core from a low mass companion whose decaying accretion supply rate
owers first the pPNe and then the lower luminosity PNe. Determining
observational signatures of different MHD engines is a work in progress.
Accretion disk theory and large scale dynamos pose many of their own
fundamental challenges, some of which I discuss in a broader context.


title:
Lambda(1405) in a baryon-meson scattering with a bound state embedded in
  the continuum

abstract:
  We investigate Lambda(1405) as a resonance in a coupled channel baryon-meson
scattering with a `bound state embedded in the continuum'(BSEC). This BSEC is
introduced by hand, as a state not originated from simple baryon-meson systems.
We assume it comes from the three-quark state.
  There appears a resonance in the Sigma pi scattering below the N Kbar
threshold when the N Kbar channel is taken to be strongly attractive. It occurs
without introducing a BSEC, just like the chiral unitary approach. When a BSEC
is introduced, a resonance also appears with a weaker baryon-meson interaction.
The corresponding peak also has a large width, and the N Kbar scattering length
is reproduced well. The interaction whose channel dependence is the same as the
one originated from the color-magnetic interaction, where no N Kbar attraction
exists, also gives a broad peak like Lambda(1405) with help of a BSEC.
  It is found that the BSEC coupling which does not vanish at the zero momentum
transfer give a larger width. In order to reproduce the observed N Kbar
scattering length, introducing a BSEC seems preferable. In our calculation, a
model gives an appropriate value when the BSEC contribution to the resonance is
roughly half of that of the N Kbar in size.


title:
Magnetization ground states and phase diagrams for a nano-sized Co
  hollow sphere : an onion-type magnetization state

abstract:
  The magnetization ground states (MGSs) for a nanosized Co hollow sphere, with
the outer radius, R < 50 nm, have been studied numerically by micromagnetic
simulation using object oriented micromagnetic framework (OOMMF). In addition
to the originally known single domain and vortex-curling states, a three
dimensional "onion" state with a corresponding analytical expression is
proposed and confirmed as one of the ground states. Two phase diagrams, one for
a single crystalline and the other for a polycrystalline nanosphere, are
obtained for the three MGSs. The result reveals that the magnetic anisotropy
has a significant effect on the phase line in the diagrams. The finite
temperature effect and the blocking properties of the nanosphere for the
magnetization reversal are discussed.


title: The three-dimensional Finite Larmor Radius Approximation

abstract:
  Following Fr\'enod and Sonnendr\"ucker, we consider the finite Larmor radius
regime for a plasma submitted to a large magnetic field and take into account
both the quasineutrality and the local thermodynamic equilibrium of the
electrons. We then rigorously establish the asymptotic gyrokinetic limit of the
rescaled and modified Vlasov-Poisson system in a three-dimensional setting with
the help of an averaging lemma.


title:
Kalinahia: Considering Quality of Service to Design and Execute
  Distributed Multimedia Applications

abstract:
  One of the current challenges of Information Systems is to ensure
semi-structured data transmission, such as multimedia data, in a distributed
and pervasive environment. Information Sytems must then guarantee users a
quality of service ensuring data accessibility whatever the hardware and
network conditions may be. They must also guarantee information coherence and
particularly intelligibility that imposes a personalization of the service.
Within this framework, we propose a design method based on original models of
multimedia applications and quality of service. We also define a supervision
platform Kalinahia using a user centered heuristic allowing us to define at any
moment which configuration of software components constitutes the best answers
to users' wishes in terms of service.


title:
Colossal electroresistance and colossal magnetoresistive step in
  paramagnetic insulating phase of single crystalline bilayered
  manganite(La$_{0.4}$Pr$_{0.6}$)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$

abstract:
  We report a significant decrease in the low-temperature resistance induced by
the application of an electric current on the $ab$-plane in the paramagnetic
insulating (PMI) state of
(La$_{0.4}$Pr$_{0.6}$)$_{1.2}$Sr$_{1.8}$Mn$_{2}$O$_{7}$. A colossal
electroresistance effect attaining -95% is observed at lower temperatures. A
colossal magnetoresistive step appears near 5T at low temperatures below 10K,
accompanied by an ultrasharp width of the insulator-metal transition. Injection
of higher currents to the crystal causes a disappearance of the steplike
transition. These findings have a close relationship with the presence of the
short-range charge-ordered clusters pinned within the PMI matrix of the crystal
studied.