title:
Structural transformations of double-walled carbon nanotube bundle under
  hydrostatic pressure

abstract:
  Three kinds of the response mechanisms to the external pressure have been
found for double-walled carbon nanotube (DWNT) bundle, depending strongly on
their average radius and symmetry. The small-diameter DWNT bundle undergoes a
small discontinuous volume change, and then deform continuously. The
intermediate-diameter DWNT bundle collapses completely after a structure phase
transition (SPT). Significantly, two SPTs exist for the larger-diameter DWNT
bundle if the outer tube has no $C_{6}$ or $C_{3}$ symmetry. It would be
interesting to search for signatures of these different structural
transformations by experimentally investigating mechanical, optical and thermal
response functions of DWNT bundle.


title: Inclusive semileptonic B decays and the determination of |V_ub|

abstract:
  We study the triple differential distribution of B-> Xu l nu, consistently
including all perturbative and non-perturbative effects through O(alphas^2
beta_0) and O(1/mb^3). The Fermi motion is parameterized in terms of a single
light-cone function for each structure function and for any value of q^2,
accounting for all subleading effects. We discuss the problems and
uncertainties related to the high-q^2 tail and to Weak Annihilation effects. We
work in the kinetic scheme, a framework characterized by a Wilsonian treatment
with a hard cutoff mu ~ 1GeV. Our method is illustrated with the extraction of
|V_ub| from some of the latest experimental data, providing a detailed estimate
of the theoretical uncertainty.


title: The Achromatic Interfero Coronagraph

abstract:
  We report on the Achromatic Interfero Coronagraph, a focal imaging device
which aims at rejecting the energy contribution of a point-like source set
on-axis, so as to make detectable its angularly-close environment (applicable
to stellar environment: circumstellar matter, faint companions, planetary
systems, but also conceivably to Active Galatic Nucleii and multiple
asteroids). With AIC, starlight rejection is based on destructive interference,
which allows exploration of the star's neighbouring at angular resolution
better than the diffraction limit of the hosting telescope. Thanks to the focus
crossing property of light, rejection is achromatic thus yielding a large
spectral bandwidth of work. Descriptions and comments are given regarding the
principle, the device itself, the constraints and limitations, and the
theoretical performance. Results are presented which demonstrate the
close-sensing capability and which show images of a companion obtained in
laboratory and 'on the sky' as well. A short pictorial description of
alternative AIC concepts, CIAXE and Open-Air CIAXE, currently under study, is
given.


title:
Geometrical and electronic structures of the (5, 3) single-walled gold
  nanotube from first-principles calculations

abstract:
  The geometrical and electronic structures of the 4 {\AA} diameter perfect and
deformed (5, 3) single-walled gold nanotube (SWGT) have been studied based upon
the density-functional theory in the local-density approximation (LDA). The
calculated relaxed geometries show clearly significant deviations from those of
the ideally rolled triangular gold sheet. It is found that the different
strains have different effects on the electronic structures and density of
states of the SWGTs. And the small shear strain can reduce the binding energy
per gold atom of the deformed SWGT, which is consistent with the experimentally
observed result. Finally, we found the finite SWGT can show the
metal-semiconductor transition.


title: Tau anomalous magnetic moment form factor at Super B/Flavor factories

abstract:
  The proposed high-luminosity B/Flavor factories offer new opportunities for
the improved determination of the fundamental physical parameters of standard
heavy leptons. Compared to the electron or the muon case, the magnetic
properties of the $\tau$ lepton are largely unexplored. We show that the
electromagnetic properties of the $\tau$, and in particular its magnetic form
factor, may be measured competitively in these facilities, using unpolarized or
polarized electron beams. Various observables of the $\tau$'s produced on top
of the $\Upsilon$ resonances, such as cross-section and normal polarization for
unpolarized electrons or longitudinal and transverse asymmetries for polarized
beams, can be combined in order to increase the sensitivity on the magnetic
moment form factor. In the case of polarized electrons, we identify a special
combination of transverse and longitudinal $\tau$ polarizations able to
disentangle this anomalous magnetic form factor from both the charge form
factor and the interference with the Z-mediating amplitude. For an integrated
luminosity of $15 \times 10^{18} b^{-1}$ one could achieve a sensitivity of
about $10^{-6}$, which is several orders of magnitude below any other existing
high- or low-energy bound on the magnetic moment. Thus one may obtain a QED
test of this fundamental quantity to a few % precision.


title:
A study of the ferromagnetic transition of $SrRuO_3$ in nanometer thick
  bilayers with $YBa_2Cu_3O_y$, $La_{1.88}Sr_{0.12}CuO_{4-y}$, Au and Cr:
  Signature of injected carriers in the pseudogap regime

abstract:
  The hypothesis regarding the existence of uncorrelated pre-formed pairs in
the pseudogap regime of superconducting $YBa_2Cu_3O_y$ is tested experimentally
using bilayers of $YBa_2Cu_3O_y$ and the itinerant ferromagnet $SrRuO_3$. In
our study, we monitor the influence of $YBa_2Cu_3O_y$ on $T_p$, the
ferromagnetic ordering temperature of $SrRuO_3$. Here, $T_p$ is the temperature
of maximum dM/dT or dR/dT where M and R are the magnetization and resistance of
$SrRuO_3$, respectively. We compare the results with similar measurements
carried out on bilayers of $La_{1.88}Sr_{0.12}CuO_{4-y}$, $Au$ and $Cr$ with
$SrRuO_3$. We find that in bilayers made of underdoped 10 nm $YBa_2Cu_3O_y$/5
nm $SrRuO_3$, the $T_p$ values are shifted to lower temperatures by up to 6-8 K
as compared to $T_p\approx 140$ K of the 5 nm thick reference $SrRuO_3$ film.
In contrast, in the other type of bilayers, which are not in the pseudogap
regime near $T_p$, only a smaller shift of up to $\pm$2 K is observed. These
differences are discussed in terms of a proximity effect, where carriers from
the $YBa_2Cu_3O_y$ layer are injected into the $SrRuO_3$ layer and vice versa.
We suggest that correlated electrons in the pseudogap regime of $YBa_2Cu_3O_y$
are responsible for the observed large $T_p$ shifts.


title: Subcritical dynamo bifurcation in the Taylor Green flow

abstract:
  We report direct numerical simulations of dynamo generation for flow
generated using a Taylor-Green forcing. We find that the bifurcation is
subcritical, and show its bifurcation diagram. We connect the associated
hysteretic behavior with hydrodynamics changes induced by the action of the
Lorentz force. We show the geometry of the dynamo magnetic field and discuss
how the dynamo transition can be induced when an external field is applied to
the flow.


title: Invariance of the relativistic one-particle distribution function

abstract:
  The one-particle distribution function is of importance both in
non-relativistic and relativistic statistical physics. In the relativistic
framework, Lorentz invariance is possibly its most fundamental property. The
present article on the subject is a contrastive one: we review, discuss
critically, and, when necessary, complete, the treatments found in the standard
literature.


title: Landen survey

abstract:
  Landen transformations are maps on the coefficients of an integral that
preserve its value. We present a brief survey of their appearnce in the
literature.


title:
Single-walled carbon nanotube bundle under hydrostatic pressure studied
  by the first-principles calculations

abstract:
  The structural, electronic, optical and vibrational properties of the
collapsed (10,10) single-walled carbon nanotube bundle under hydrostatic
pressure have been studied by the first-principles calculations. Some features
are observed in the present study: First, a collapsed structure is found, which
is distinct from both of the herringbone and parallel structures obtained
previously. Secondly, a pseudo-gap induced by the collapse appears along the
symmetry axis \textit{$\Gamma $X}. Thirdly, the relative orientation between
the collapsed tubes has an important effect on their electronic, optical and
vibrational properties, which provides an efficient experimental method to
distinguish unambiguously three different collapsed structures.


title:
Electronic and Transport Properties of Radially Deformed Double-walled
  Carbon Nanotube Intramolecular Junction

abstract:
  The electronic and transport property of a radially deformed double-walled
carbon nanotube (DWNT) intramolecular junction (IMJ) has been studied by the
tight-binding (TB) model combined with the first-principle calculations. The
geometrical structures of the DWNT IMJ have been first optimized in energy by
the universal force field (UFF) method. It is found that when heavily squashed,
the DWNT will become an insulator-coated metallic wire, and the conductance
near the Fermi level has been significantly changed by the radial squash.
Specially, several resonance conductance peaks appear at some energies in the
conduction band of the squashed DWNT IMJ. Finally, we have also investigated
the conductance variation due to change of the length of the central
semiconductor in the squashed DWNT IMJ. Furthermore, a promising pure carbon
nanoscale electronic device is proposed based on the DWNT IMJ.


title: Intergrowth and thermoelectric properties in the Bi-Ca-Co-O system

abstract:
  Single crystals of the Bi-Ca-Co-O system have been grown using the flux
method with cooling from 900$\celsius$ and 950$\celsius$, respectively. The
single crystals are characterized by transmission electron microscopy and X-ray
diffraction. The misfit cobaltite
[Ca$_2$Bi$_{1.4}$Co$_{0.6}$O$_4$]$^{RS}$[CoO$_2$]$_{1.69}$ single crystals with
quadruple ($n$=4) rocksalt (RS) layer are achieved with cooling from
900$\celsius$. Such crystal exhibits room-temperature thermoelectric power
(TEP) of 180$\mu$V/K, much larger than that in Sr-based misfit cobaltites with
quadruple RS layer. However, intergrowth of single crystals of quadruple
($n$=4) and triple ($n$=3) RS-type layer-based misfit cobaltites is observed
with cooling from 950$\celsius$. Both of TEP and resistivity were obviously
enhanced by the intergrowth compared to
[Ca$_2$Bi$_{1.4}$Co$_{0.6}$O$_4$]$^{RS}$[CoO$_2$]$_{1.69}$ single crystal,
while the power factor at room temperature remains unchanged.


title:
$B\to K$ Transition Form Factor up to ${\cal O}(1/m^2_b)$ within the
  $k_T$ Factorization Approach

abstract:
  In the paper, we apply the $k_T$ factorization approach to deal with the
$B\to K$ transition form factor $F^{B\to K}_{+,0}(q^2)$ in the large recoil
regions. The B-meson wave functions $\Psi_B$ and $\bar\Psi_B$ that include the
three-particle Fock states' contributions are adopted to give a consistent PQCD
analysis of the form factor up to ${\cal O} (1/m^2_b)$. It has been found that
both the wave functions $\Psi_B$ and $\bar\Psi_B$ can give sizable
contributions to the form factor and should be kept for a better understanding
of the $B$ meson decays. Then the contributions from different twist structures
of the kaon wavefunction are discussed, including the $SU_f(3)$-breaking
effects. A sizable contribution from the twist-3 wave function $\Psi_p$ is
found, whose model dependence is discussed by taking two group of parameters
that are determined by different distribution amplitude moments obtained in the
literature. It is also shown that $F^{B\to K}_{+,0}(0)=0.30\pm0.04$ and
$[F^{B\to K}_{+,0}(0)/F^{B\to \pi}_{+,0}(0)]=1.13\pm0.02$, which are more
reasonable and consistent with the light-cone sum rule results in the large
recoil regions.


title: Primitive Divisors in Arithmetic Dynamics

abstract:
  Let F(z) be a rational function in Q(z) of degree at least 2 with F(0) = 0
and such that F does not vanish to order d at 0. Let b be a rational number
having infinite orbit under iteration of F, and write F^n(b) = A_n/B_n as a
fraction in lowest terms. We prove that for all but finitely many n > 0, the
numerator A_n has a primitive divisor, i.e., there is a prime p such that p
divides A_n and p does not divide A_i for all i < n. More generally, we prove
an analogous result when F is defined over a number field and 0 is a periodic
point for F.


title:
Mixed Integer Linear Programming For Exact Finite-Horizon Planning In
  Decentralized Pomdps

abstract:
  We consider the problem of finding an n-agent joint-policy for the optimal
finite-horizon control of a decentralized Pomdp (Dec-Pomdp). This is a problem
of very high complexity (NEXP-hard in n >= 2). In this paper, we propose a new
mathematical programming approach for the problem. Our approach is based on two
ideas: First, we represent each agent's policy in the sequence-form and not in
the tree-form, thereby obtaining a very compact representation of the set of
joint-policies. Second, using this compact representation, we solve this
problem as an instance of combinatorial optimization for which we formulate a
mixed integer linear program (MILP). The optimal solution of the MILP directly
yields an optimal joint-policy for the Dec-Pomdp. Computational experience
shows that formulating and solving the MILP requires significantly less time to
solve benchmark Dec-Pomdp problems than existing algorithms. For example, the
multi-agent tiger problem for horizon 4 is solved in 72 secs with the MILP
whereas existing algorithms require several hours to solve it.


title: Surface oscillations in channeled snow flows

abstract:
  An experimental device has been built to measure velocity profiles and
friction laws in channeled snow flows. The measurements show that the velocity
depends linearly on the vertical position in the flow and that the friction
coefficient is a first-order polynomial in velocity (u) and thickness (h) of
the flow. In all flows, oscillations on the surface of the flow were observed
throughout the channel and measured at the location of the probes. The
experimental results are confronted with a shallow water approach. Using a
Saint-Venant modeling, we show that the flow is effectively uniform in the
streamwise direction at the measurement location. We show that the surface
oscillations produced by the Archimedes's screw at the top of the channel
persist throughout the whole length of the channel and are the source of the
measured oscillations. This last result provides good validation of the
description of such channeled snow flows by a Saint-Venant modeling.


title:
Analysis of the SN1987A two-stage explosion hypothesis with account for
  the MSW neutrino flavour conversion

abstract:
  Detection of 5 events by the Liquid Scintillation Detector (LSD) on February,
23, 1987 was interpreted in the literature as the detection of neutrinos from
the first stage of the two-stage supernova collapse. We pose rigid constraints
on the properties of the first stage of the collapse, taking into account
neutrino flavour conversion due to the MSW-effect and general properties of
supernova neutrino emission. The constraints depend on the unknown neutrino
mass hierarchy and mixing angle \theta_{13}.


title: Tomography for amplitudes of hard exclusive processes

abstract:
  We discuss which part of information about hadron structure encoded in the
Generalized Parton Distributions (GPDs) [part of total GPD image] can be
restored from the known amplitude of a hard exclusive process. The physics
content of this partial image is analyzed. Among other things, we show that
this partial image contains direct information about how the target hadron
responses to the (string) quark-antiquark operator of {\it arbitrary} spin J.
Explicit equations relating physics content of the partial image of GPDs
directly to the data are derived. Also some new results concerning the dual
parametrization of GPDs are presented.


title: Radiative gravitino decays from R-parity violation

abstract:
  We study radiative gravitino decay within the framework of R-violating
supersymmetry. For trilinear R-violating couplings that involve the third
generation of fermions, or for light gravitinos, we find that the radiative
loop-decay $\tilde{G} \to \gamma \nu$ dominates over the tree-level ones for a
wide set of parameters. We calculate the gravitino decay width and study its
implications for cosmology and collider physics. Slow-decaying gravitinos are
good dark matter candidates, for a range of parameters that would also predict
observable R-violating signatures in colliders. In general the branching ratios
are very dependent on the relative hierarchies of R-violating operators, and
may provide relevant information on the flavour structure of the underlying
fundamental theory.


title: Symmetries of perturbed conformal field theories

abstract:
  The symmetries of perturbed conformal field theories are analysed. We explain
which generators of the chiral algebras of a bulk theory survive a perturbation
by an exactly marginal bulk field. We also study the behaviour of D-branes
under current-current bulk deformations. We find that the branes always
continue to preserve as much symmetry as they possibly can, i.e. as much as is
preserved in the bulk. We illustrate these findings with several examples,
including permutation branes in WZW models and B-type D-branes in Gepner
models.


title: Generalized Neighbor-Interaction Models Induced by Nonlinear Lattices

abstract:
  It is shown that the tight-binding approximation of the nonlinear
Schr\"odinger equation with a periodic linear potential and periodic in space
nonlinearity coefficient gives rise to a number of nonlinear lattices with
complex, both linear and nonlinear, neighbor interactions. The obtained
lattices present non-standard possibilities, among which we mention a
quasi-linear regime, where the pulse dynamics obeys essentially the linear
Schr{\"o}dinger equation. We analyze the properties of such models both in
connection with their modulational stability, as well as in regard to the
existence and stability of their localized solitary wave solutions.


title:
Time for pulse traversal through slabs of dispersive and negative
  ($\epsilon$, $\mu$) materials

abstract:
  The traversal times for an electromagnetic pulse traversing a slab of
dispersive and dissipative material with negative dielectric permittivity
($\epsilon$) and magnetic permeability ($\mu$) have been calculated by using
the average flow of electromagnetic energy in the medium. The effects of
bandwidth of the pulse and dissipation in the medium have been investigated.
While both large bandwidth and large dissipation have similar effects in
smoothening out the resonant features that appear due to Fabry-P\'{e}rot
resonances, large dissipation can result in very small or even negative
traversal times near the resonant frequencies. We have also investigated the
traversal times and Wigner delay times for obliquely incident pulses and
evanescent pulses. The coupling to slab plasmon polariton modes in frequency
ranges with negative $\epsilon$ or $\mu$ is shown to result in large traversal
times at the resonant conditions. We also find that the group velocity mainly
contributes to the delay times for pulse propagating across a slab with n=-1.
We have checked that the traversal times are positive and subluminal for pulses
with sufficiently large bandwidths.


title:
Radiation-cooled Dew Water Condensers Studied by Computational Fluid
  Dynamic (CFD)

abstract:
  Harvesting condensed atmospheric vapour as dew water can be an alternative or
complementary potable water resource in specific arid or insular areas. Such
radiation-cooled condensing devices use already existing flat surfaces (roofs)
or innovative structures with more complex shapes to enhance the dew yield. The
Computational Fluid Dynamic - CFD - software PHOENICS has been programmed and
applied to such radiation cooled condensers. For this purpose, the sky
radiation is previously integrated and averaged for each structure. The
radiative balance is then included in the CFD simulation tool to compare the
efficiency of the different structures under various meteorological parameters,
for complex or simple shapes and at various scales. It has been used to precise
different structures before construction. (1) a 7.32 m^2 funnel shape was
studied; a 30 degree tilted angle (60 degree cone half-angle) was computed to
be the best compromise for funnel cooling. Compared to a 1 m^2 flat condenser,
the cooling efficiency was expected to be improved by 40%. Seventeen months
measurements in outdoor tests presented a 138 % increased dew yield as compared
to the 1 m^2 flat condenser. (2) The simulation results for 5 various condenser
shapes were also compared with experimental measurement on corresponding pilots
systems: 0.16 m^2 flat planar condenser, 1 m^2 and 30 degree tilted planar
condenser, 30 m^2 and 30 degree tilted planar condenser, 255 m^2 multi ridges,
a preliminary construction of a large scale dew plant being implemented in the
Kutch area (Gujarat, India).


title: Generic measures for hyperbolic flows on non compact spaces

abstract:
  We consider the geodesic flow on a complete connected negatively curved
manifold. We show that the set of invariant borel probability measures contains
a dense $G_\delta$-subset consisting of ergodic measures fully supported on the
non-wandering set. We also trat the case of non-positively curved manifolds and
provide general tools to deal with hyperbolic systems defined on non-compact
spaces.


title: Evolution of Massive Haloes in non-Gaussian Scenarios

abstract:
  We have performed high-resolution cosmological N-body simulations of a
concordance LCDM model to study the evolution of virialized, dark matter haloes
in the presence of primordial non-Gaussianity. Following a standard procedure,
departures from Gaussianity are modeled through a quadratic Gaussian term in
the primordial gravitational potential, characterized by a dimensionless
non-linearity strength parameter f_NL. We find that the halo mass function and
its redshift evolution closely follow the analytic predictions of Matarrese et
al.(2000). The existence of precise analytic predictions makes the observation
of rare, massive objects at large redshift an even more attractive test to
detect primordial non-Gaussian features in the large scale structure of the
universe.


title:
Sound velocity and absorption measurements under high pressure using
  picosecond ultrasonics in diamond anvil cell. Application to the stability
  study of AlPdMn

abstract:
  We report an innovative high pressure method combining the diamond anvil cell
device with the technique of picosecond ultrasonics. Such an approach allows to
accurately measure sound velocity and attenuation of solids and liquids under
pressure of tens of GPa, overcoming all the drawbacks of traditional
techniques. The power of this new experimental technique is demonstrated in
studies of lattice dynamics, stability domain and relaxation process in a
metallic sample, a perfect single-grain AlPdMn quasicrystal, and rare gas, neon
and argon. Application to the study of defect-induced lattice stability in
AlPdMn up to 30 GPa is proposed. The present work has potential for application
in areas ranging from fundamental problems in physics of solid and liquid
state, which in turn could be beneficial for various other scientific fields as
Earth and planetary science or material research.


title:
Positive and negative pressure effects on the magnetic ordering and the
  Kondo effect in the compound Ce2RhSi3

abstract:
  The competition between magnetic ordering and the Kondo effect in Ce2RhSi3,
ordering antiferromagnetically at 7 K, is investigated by the measurements of
magnetization, heat capacity and electrical resistivity on the solid solutions,
Ce(2-x)La(x)RhSi3, Ce(2-y)Y(y)RhSi3, and Ce2RhSi(3-z)Ge(z), as well as by high
pressure studies on this compound. The trends in the Kondo and Neel temperature
variations among these alloys are compared to infer the roles of unit-cell
volume and electronic structure changes. On the basis of the results, we infer
that this compound lies at the peak of Doniach-magnetic-phase-diagram. The high
pressure electrical resistivity data indicate that the quantum critical point
for this compound is in the vicinity of 4 GPa.


title:
Gravitational Collapse to Toroidal and Higher Genus asymptotically AdS
  Black Holes

abstract:
  We match collapsing inhomogeneous as well as spatially homogeneous but
anisotropic spacetimes to vacuum static exteriors with a negative cosmological
constant and planar or hyperbolic symmetry. The collapsing interiors include
the inhomogeneous solutions of Szekeres and of Barnes, which in turn include
the Lemaitre-Tolman and the McVittie solutions. The collapse can result in
toroidal or higher genus asymptotically AdS black holes.


title:
Schwinger's Magnetic Model of Matter: Can It Help Us With Grand
  Unification?

abstract:
  Many have argued that research on grand unification or local realistic
physics will not be truly relevant until it makes predictions verified by
experiment, different from the prediction of prior theory (the standard model).
This paper proposes a new strategy (and candidate Lagrangians) for such models;
that strategy in turn calls for reconsideration of Schwinger's magnetic model
of matter. High priority should be given to experiments which fully confirm or
deny recent scattering calculations which suggest the presence of van der Waals
effects in low energy p-p and pi-pi scattering, consistent with Schwinger's
model and inconsistent with QCD as we know it (with a mass gap). I briefly
discuss other evidence, which does not yet rule out Schwinger's theory. A
recent analysis of hadron masses also seems more consistent with the Schwinger
model than with QCD.


title: Nonlinear viscoelastic dynamics of nano-confined water

abstract:
  The viscoelastic dynamics of nano-confined water is studied by means of
atomic force microscopy (AFM). We observe a nonlinear viscoelastic behavior
remarkably similar to that widely observed in metastable complex fluids. We
show that the origin of the measured nonlinear viscoelasticity in nano-confined
water is a strain rate dependent relaxation time and slow dynamics. By
measuring the viscoelastic modulus at different frequencies and strains, we
find that the intrinsic relaxation time of nano-confined water is in the range
0.1-0.0001 s, orders of magnitude longer than that of bulk water, and
comparable to the dielectric relaxation time measured in supercooled water at
170-210 K.


title: On embedding well-separable graphs

abstract:
  Call a simple graph $H$ of order $n$ well-separable, if by deleting a
separator set of size $o(n)$ the leftover will have components of size at most
$o(n)$. We prove, that bounded degree well-separable spanning subgraphs are
easy to embed: for every $\gamma >0$ and positive integer $\Delta$ there exists
an $n_0$ such that if $n>n_0$, $\Delta(H) \le \Delta$ for a well-separable
graph $H$ of order $n$ and $\delta(G) \ge (1-{1 \over 2(\chi(H)-1)} + \gamma)n$
for a simple graph $G$ of order $n$, then $H \subset G$. We extend our result
to graphs with small band-width, too.


title: Quarkonium production in coherent hadron-hadron interactions at the LHC

abstract:
  The photoproduction of quarkonium in coherent hadron-hadron (pp/pA/AA$)
interactions for LHC energies is an important tool to investigate the QCD
dynamics at high energies. In this paper we estimate the integrated cross
section and rapidity distribution for J/Psi and Upsilon production using the
Color Glass Condensate (CGC) formalism. We predict large rates, implying that
the experimental identification could be feasible at the LHC.


title:
Search for New Physics in High Mass Electron-Positron Events in ppbar
  Collisions at sqrt(s) = 1.96 TeV

abstract:
  We report the results of a search for a narrow resonance in electron-positron
events in the invariant mass range of 150-950 GeV/c^2 using 1.3 fb^-1 of ppbar
collision data at sqrt(s) = 1.96 TeV collected by the CDF II detector at
Fermilab. No significant evidence of such a resonance is observed and we
interpret the results to exclude the standard model-like Z' with a mass below
923 GeV/c^2 and the Randall-Sundrum graviton with a mass below 807 GeV/c^2 for
k/M_pl=0.1, both at the 95% confidence level. Combining with di-photon data
excludes the Randall-Sundrum graviton for masses below 889 GeV/c^2 for
k/M_pl=0.1.


title: Tilings With Very Elastic Tiles

abstract:
  We consider tiles of some fixed size, with an associated weighting on the
shapes of tile, of total mass 1. We study the pressure, $p$, of tilings with
those tiles; the pressure, one over the volume times the logarithm of the
partition function. (The quantity we define as "pressure" could, perhaps
equally harmoniously with physics notation, be called "entropy per volume",
neither nomenclature is "correct".) We let $\hat p^0$ (easy to compute) be the
pressure in the limit of absolute smoothness (the weighting function is
constant). Then as smoothness, suitably defined, increases, $p$ converges to
$\hat p^0$, uniformly in the volume. It is the uniformity requirement that
makes the result non-trivial. This seems like a very basic result in the theory
of pressure of tilings. Though at the same time, perhaps non-glamorous, being
bereft of geometry and not very difficult. The problem arose for us out of
study of a problem in mathematical physics, associated to a model of
ferromagnetism.


title: Heavy flavour production in ALICE

abstract:
  We review the most recent studies on the performance of ALICE in heavy
flavour production measurements in both hadronic and semileptonic decay
channels.


title: Rate and Power Allocation for Discrete-Rate Link Adaptation

abstract:
  Link adaptation, in particular adaptive coded modulation (ACM), is a
promising tool for bandwidth-efficient transmission in a fading environment.
The main motivation behind employing ACM schemes is to improve the spectral
efficiency of wireless communication systems. In this paper, using a finite
number of capacity achieving component codes, we propose new transmission
schemes employing constant power transmission, as well as discrete and
continuous power adaptation, for slowly varying flat-fading channels.
  We show that the proposed transmission schemes can achieve throughputs close
to the Shannon limits of flat-fading channels using only a small number of
codes. Specifically, using a fully discrete scheme with just four codes, each
associated with four power levels, we achieve a spectral efficiency within 1 dB
of the continuous-rate continuous-power Shannon capacity. Furthermore, when
restricted to a fixed number of codes, the introduction of power adaptation has
significant gains with respect to ASE and probability of no transmission
compared to a constant power scheme.


title: On the Feigel Effect: Extraction of Momentum from Vacuum?

abstract:
  The Green-function formalism for the electromagnetic field in a
magnetoelectric (ME) medium is constructed, as a generalization of conventional
Casimir theory. Zero temperature is assumed. It is shown how the formalism
predicts electromagnetic momentum to be extracted from the vacuum field, just
analogous to how energy is extracted in the Casimir case. The possibility of
extracting momentum from vacuum was discussed recently by Feigel [Phys. Rev.
Lett. 92, 020404 (2004)]. By contrast to Feigel's approach, we assume that the
ME coupling occurs naturally, and is not produced by external strong fields. We
also find the same effect qualitatively via another route, by considering one
single electromagnetic mode.


title:
Decoherence of coupled electron spins via nuclear spin dynamics in
  quantum dots

abstract:
  In double quantum dots, the exchange interaction between two electron spins
renormalizes the excitation energy of pair-flips in the nuclear spin bath,
which in turn modifies the non-Markovian bath dynamics. As the energy
renormalization varies with the Overhauser field mismatch between the quantum
dots, the electron singlet-triplet decoherence resulting from the bath dynamics
depends on sampling of nuclear spin states from an ensemble, leading to the
transition from exponential decoherence in single-sample dynamics to power-law
decay under ensemble averaging. In contrast, the decoherence of a single
electron spin in one dot is essentially the same for different choices of the
nuclear spin configuration.


title:
New homogeneous iron abundances of double-mode Cepheids from
  high-resolution echelle spectroscopy

abstract:
  Aims: We define the relationship between the double-mode pulsation of
Cepheids and metallicity in a more accurate way, determine the empirical
metallicities of double-mode Cepheids from homogeneous, high-resolution
spectroscopic data, and study of the period-ratio -- metallicity dependence.
Methods: The high S/N echelle spectra obtained with the FEROS spectrograph were
analyzed using a self-developed IRAF script, and the iron abundances were
determined by comparing with synthetic spectra assuming LTE. Results: Accurate
[Fe/H] values of 17 galactic beat Cepheids were determined. All these stars
have solar or slightly subsolar metallicity. Their period ratio P1/P0 shows
strong correlation with their derived [Fe/H] values. The corresponding period
ratio -- metallicity relation has been evaluated.


title:
Renormalization Group Analysis of a Gursey Model Inspired Field Theory
  II

abstract:
  Recently a model, which is equivalent to the scalar form of Gursey model, is
shown to be a nontrivial field theoretical model when it is gauged with a SU(N)
field. In this paper we study another model that is equivalent to the vector
form of the Gursey model. We get a trivial theory when it is coupled with a
scalar field. This result changes drastically when it is coupled with an
additional SU(N) field. We find a nontrivial field theoretical model under
certain conditions.


title: KLOE measurement of the charged kaon absolute semileptonic BR's

abstract:
  This paper is devoted to the measurement of the fully inclusive absolute
branching ratios of the charged kaon semileptonic decays,
$K^{\pm}\to\pi^0e^\pm\nu(\gamma)$ and $K^\pm \to \pi^0\mu^\pm\nu(\gamma)$. The
measurements have been done using a tag technique, employing the two-body
decays, $K^\pm \to \mu^\pm\nu$ and $K^\pm \to \pi^\pm\pi^0$, and using a sample
of about 410 pb$^{-1}$ collected during the 2001 and 2002 data taking of the
KLOE experiment at Daphne, the Frascati $\phi$-factory. The results obtained
are BR(K$^\pm_{e3}$) = $0.04965 (38)_{Stat} (37)_{Syst}$ and BR(K$^\pm_{\mu3}$)
= $0.03233 (29)_{Stat} (26)_{Syst}$.


title:
Mixings of 4-quark components in light non-singlet scalar mesons in QCD
  sum rules

abstract:
  Mixings of 4-quark components in the non-singlet scalar mesons are studied in
the QCD sum rules. We propose a formulation to evaluate the cross correlators
of q\bar q and qq\bar q \bar q operators and to define the mixings of different
Fock states in the sum rule. It is applied to the non-singlet scalar mesons,
a_0 and K_0^\ast. It is found that the 4-quark operators predict lower masses
than the q\bar q operators and that the 4-quark states occupy about 70-90% of
the lowest mass states.


title: Renyi Entropy of the XY Spin Chain

abstract:
  We consider the one-dimensional XY quantum spin chain in a transverse
magnetic field. We are interested in the Renyi entropy of a block of L
neighboring spins at zero temperature on an infinite lattice. The Renyi entropy
is essentially the trace of some power $\alpha$ of the density matrix of the
block. We calculate the asymptotic for $L \to \infty$ analytically in terms of
Klein's elliptic $\lambda$ - function. We study the limiting entropy as a
function of its parameter $\alpha$. We show that up to the trivial addition
terms and multiplicative factors, and after a proper re-scaling, the Renyi
entropy is an automorphic function with respect to a certain subgroup of the
modular group; moreover, the subgroup depends on whether the magnetic field is
above or below its critical value. Using this fact, we derive the
transformation properties of the Renyi entropy under the map $\alpha \to
\alpha^{-1}$ and show that the entropy becomes an elementary function of the
magnetic field and the anisotropy when $\alpha$ is a integer power of 2, this
includes the purity $tr \rho^2$. We also analyze the behavior of the entropy as
$\alpha \to 0$ and $\infty$ and at the critical magnetic field and in the
isotropic limit [XX model].


title: Simple theory of the measured current through quantum dots

abstract:
  A simple theory of the detected current I(t) flowing through charge qubits --
quantum dots -- is proposed in terms of standard continuous measurement theory.
Applied to a double dot, our formalism easily confirms previous results on
quantum Zeno effect, driven by growing ammeter performance gamma. Due to the
transparent formalism, we can calculate the exact fluctuation spectrum S(omega)
of the detected current, containing a significant Lorentzian peak near the Rabi
frequency of the double dot.


title: On Lee Smolin's The Trouble with Physics

abstract:
  Lee Smolin's casual accounting of special and general relativity in The
Trouble with Physics raises an interesting question: is it possible to develop
a legitimate argument concerning string theories starting from a shaky basis?
This is apparently what Lee Smolin succeeded in doing when he wrote The Trouble
with Physics. The book's shortcomings are nevertheless troublesome.


title:
A Combined Spitzer and Chandra Survey of Young Stellar Objects in the
  Serpens Cloud Core

abstract:
  We present Spitzer and Chandra observations of the nearby (~260 pc) embedded
stellar cluster in the Serpens Cloud Core. We observed, using Spitzer's IRAC
and MIPS instruments, in six wavelength bands from 3 to 70 ${\mu}m$, to detect
thermal emission from circumstellar disks and protostellar envelopes, and to
classify stars using color-color diagrams and spectral energy distributions
(SEDs). These data are combined with Chandra observations to examine the
effects of circumstellar disks on stellar X-ray properties. Young diskless
stars were also identified from their increased X-ray emission. We have
identified 138 YSOs in Serpens: 22 class 0/I, 16 flat spectrum, 62 class II, 17
transition disk, and 21 class III stars; 60 of which exhibit X-ray emission.
Our primary results are the following: 1.) ten protostars detected previously
in the sub-millimeter are detected at lambda < 24 microns, seven at lambda < 8
microns, 2.) the protostars are more closely grouped than more evolved YSOs
(median separation : ~0.024 pc, and 3.) the luminosity and temperature of the
X-ray emitting plasma around these YSOs does not show any significant
dependence on evolutionary class. We combine the infrared derived values of AK
and X-ray values of NH for 8 class III objects and find that the column density
of hydrogen gas per mag of extinctions is less than half the standard
interstellar value, for AK > 1. This may be the result of grain growth through
coagulation and/or the accretion of volatiles in the Serpens cloud core.


title:
Non-parametric inversion of gravitational lensing systems with few
  images using a multi-objective genetic algorithm

abstract:
  Galaxies acting as gravitational lenses are surrounded by, at most, a handful
of images. This apparent paucity of information forces one to make the best
possible use of what information is available to invert the lens system. In
this paper, we explore the use of a genetic algorithm to invert in a
non-parametric way strong lensing systems containing only a small number of
images. Perhaps the most important conclusion of this paper is that it is
possible to infer the mass distribution of such gravitational lens systems
using a non-parametric technique. We show that including information about the
null space (i.e. the region where no images are found) is prerequisite to avoid
the prediction of a large number of spurious images, and to reliably
reconstruct the lens mass density. While the total mass of the lens is usually
constrained within a few percent, the fidelity of the reconstruction of the
lens mass distribution depends on the number and position of the images. The
technique employed to include null space information can be extended in a
straightforward way to add additional constraints, such as weak lensing data or
time delay information.


title:
Three-dimensional Monte Carlo simulations of the quantum linear
  Boltzmann equation

abstract:
  Recently the general form of a translation-covariant quantum Boltzmann
equation has been derived which describes the dynamics of a tracer particle in
a quantum gas. We develop a stochastic wave function algorithm that enables
full three-dimensional Monte Carlo simulations of this equation. The simulation
method is used to study the approach to equilibrium for various scattering
cross sections and to determine dynamical deviations from Gaussian statistics
through an investigation of higher-order cumulants. Moreover, we examine the
loss of coherence of superpositions of momentum eigenstates and determine the
corresponding decoherence time scales to quantify the transition from quantum
to classical behavior of the state of the test particle.


title:
On how good DFT exchange-correlation functionals are for H bonds in
  small water clusters: Benchmarks approaching the complete basis set limit

abstract:
  The ability of several density-functional theory (DFT) exchange-correlation
functionals to describe hydrogen bonds in small water clusters (dimer to
pentamer) in their global minimum energy structures is evaluated with reference
to second order Moeller Plesset perturbation theory (MP2). Errors from basis
set incompleteness have been minimized in both the MP2 reference data and the
DFT calculations, thus enabling a consistent systematic evaluation of the true
performance of the tested functionals. Among all the functionals considered,
the hybrid X3LYP and PBE0 functionals offer the best performance and among the
non-hybrid GGA functionals mPWLYP and PBE1W perform the best. The popular BLYP
and B3LYP functionals consistently underbind and PBE and PW91 display rather
variable performance with cluster size.


title:
Measurement of e^+e^- to pi^+pi^-J/psi Cross Section via Initial State
  Radiation at Belle

abstract:
  The cross section for e^+e^- to pi^+pi^-J/psi between 3.8 and 5.5 GeV/c^2 is
measured using a 548 fb^{-1} data sample collected on or near the Upsilon(4S)
resonance with the Belle detector at KEKB. A peak near 4.25 GeV/c^2,
corresponding to the so called Y(4260), is observed. In addition, there is
another cluster of events at around 4.05 GeV/c^2. A fit using two interfering
Breit-Wigner shapes describes the data better than one that uses only the
Y(4260), especially for the lower mass side of the 4.25 GeV enhancement.


title: Representation of finite connective spaces

abstract:
  After recalling the definition of connectivity spaces and some of their main
properties, a way is proposed to represent finite connectivity spaces by
directed simple graphs. Then a connectivity structure is associated to each
tame link. It is showed that all spaces of a certain class (the iterated
Brunnian ones) admit representations by links. Finally, I conjecture that every
finite connectivity space is representable by a link.
  -----
  Apres un rappel de la definition des espaces connectifs et de certaines de
leurs principales proprietes, nous proposons une maniere de representer les
espaces connectifs finis par des graphes simples orientes, puis nous associons
a tout entrelacs une structure connective. Nous montrons que tout espace d'une
certaine classe (les espaces brunniens iteres) admet une representation par
entrelacs, et nous conjecturons finalement que tout espace connectif fini est
representable par entrelacs.


title: Development of Tracking Detectors with industrially produced GEM Foils

abstract:
  The planned tracking upgrade of the STAR experiment at RHIC includes a
large-area GEM tracker used to determine the charge sign of electrons and
positrons produced from W+(-) decays. For such a large-scale project commercial
availability of GEM foils is necessary. We report first results obtained with a
triple GEM detector using GEM foils produced by Tech-Etch Inc. of Plymouth, MA,
USA. Measurements of gain uniformity, long-term stability as well as
measurements of the energy resolution for X-Rays are compared to results
obtained with an identical detector using GEM foils produced at CERN. A quality
assurance procedure based on optical tests using an automated high-resolution
scanner has been established, allowing a study of the correlation of the
observed behavior of the detector and the geometrical properties of the GEM
foils. Detectors based on Tech-Etch and CERN produced foils both show good
uniformity of the gain over the active area and stable gain after an initial
charge-up period, making them well suited for precision tracking applications.


title: A polarizable ion model for the structure of molten AgI

abstract:
  The results are reported of the molecular dynamics simulations of the
coherent static structure factor of molten AgI at 923 K using a polarizable ion
model. This model is based on a rigid ion potential, to which the many body
interactions due to the anions induced polarization are added. The calculated
structure factor is in better agreement with recent neutron diffraction data
than that obtained by using simple rigid ion pair potentials. The
Voronoi-Delaunay method has been applied to study the relationship between
voids in the spatial distribution of cations and the prepeak of the structure
factor.


title:
Particle multiplicities in Lead-Lead collisions at the LHC from
  non-linear evolution with running coupling

abstract:
  We present predictions for the pseudo-rapidity density of charged particles
produced in central Pb-Pb collisions at the LHC. Particle production in such
collisions is calculated in the framework of k_t-factorization. The nuclear
unintegrated gluon distributions at LHC energies are determined from numerical
solutions of the Balitsky-Kovchegov equation including recently calculated
running coupling corrections. The initial conditions for the evolution are
fixed by fitting RHIC data at collision energies \sqrt{s}}=130 and 200 GeV per
nucleon. We obtain dN^{Pb-Pb}_{ch}/d\eta (\sqrt{s}=5.5 TeV, \eta=0)\approx
1290\div 1480.


title:
High-order harmonic generation from diatomic molecules with large
  internuclear distance: The effect of two-center interference

abstract:
  In the present paper, we investigate the high-order harmonic generation (HHG)
from diatomic molecules with large internuclear distance using a strong field
approximation (SFA) model. We find that the hump and dip structure emerges in
the plateau region of the harmonic spectrum, and the location of this striking
structure is sensitive to the laser intensity. Our model analysis reveals that
two-center interference as well as the interference between different
recombination electron trajectories are responsible for the unusual enhanced or
suppressed harmonic yield at a certain order, and these interference effects
are greatly influenced by the laser parameters such as intensity.


title: An empirical model for the beams of radio pulsars

abstract:
  Motivated by recent results on the location of the radio emission in pulsar
magnetospheres, we have developed a model which can account for the large
diversity found in the average profile shapes of pulsars. At the centre of our
model lies the idea that radio emission at a particular frequency arises from a
wide range of altitudes above the surface of the star and that it is confined
to a region close to the last open field lines. We assert that the radial
height range over which emission occurs is responsible for the complex average
pulse shapes rather than the transverse (longitudinal) range proposed in most
current models. By implementing an abrupt change in the height range to
discriminate between young, short-period, highly-energetic pulsars and their
older counterparts, we obtain the observed transition between the simple and
complex average pulse profiles observed in each group respectively. Monte Carlo
simulations are used to demonstrate the match of our model to real
observations.


title:
The behavior of non-linear anisotropies in bouncing Bianchi I models of
  loop quantum cosmology

abstract:
  In homogeneous and isotropic loop quantum cosmology, gravity can behave
repulsively at Planckian energy densities leading to the replacement of the big
bang singularity with a big bounce. Yet in any bouncing scenario it is
important to include non-linear effects from anisotropies which typically grow
during the collapsing phase. We investigate the dynamics of a Bianchi I
anisotropic model within the framework of loop quantum cosmology. Using
effective semi-classical equations of motion to study the dynamics, we show
that the big bounce is still predicted with only differences in detail arising
from the inclusion of anisotropies. We show that the anisotropic shear term
grows during the collapsing phase, but remains finite through the bounce.
Immediately following the bounce, the anisotropies decay and with the inclusion
of matter with equation of state $w < +1$, the universe isotropizes in the
expanding phase.


title:
Cavity polaritons in the presence of symmetry-breaking disorder:
  closed-path time formalism

abstract:
  According to the mean-field theory of Zittartz, when subject to a
symmetry-breaking disorder, the order parameter and the energy gap of an
excitonic insulator are gradually suppressed up to a critical disorder
strength. Recently, Marchetti, Simons, and Littlewood have used a replica trick
to investigate the effects of disorder on the condensation of cavity
polaritons. Within their nonlinear sigma model, it was found that the
saddle-point equations assume the form reported previously by Zittartz in the
contest of the symmetry broken excitonic insulator, but with an order
parameter, to which both photons and excitons contribute. In this paper, we
apply a closed-path time Green's function approach as an alternative to the
replica technique to formulate a nonperturbative description of cavity
polaritons in the presence of a symmetry-breaking disorder. A field theoretical
method is used to derive the Schwinger-Dyson equations for the average photon
field and the average single-particle Green's function. In contrast with the
nonlinear sigma model and the corresponding saddle-point equations, we obtain
that the exact Schwinger-Dyson equations cannot be mapped to the corresponding
equations derived by Zittartz. This result not only shows that the theory of
Zittartz cannot be applied to the excitons in a disordered quantum well coupled
to the cavity photons with only minor modifications, but arises a question
about the validity of the replica trick as well.


title:
How Large is the Intrinsic Flux Noise of a Magnetic Flux Quantum, of
  Half a Flux Quantum and of a Vortex-Free Superconductor?

abstract:
  This article addresses the question whether the magnetic flux of stationary
vortices or of half flux quanta generated by frustrated superconducting rings
is noisy. It is found that the flux noise generated intrinsically by a
superconductor is, in good approximation, not enhanced by stationary vortices.
Half flux quanta generated by $\pi$-rings are characterized by considerably
larger noise.


title:
Coupling biochemistry and mechanics in cell adhesion: a model for
  inhomogeneous stress fiber contraction

abstract:
  Biochemistry and mechanics are closely coupled in cell adhesion. At sites of
cell-matrix adhesion, mechanical force triggers signaling through the
Rho-pathway, which leads to structural reinforcement and increased
contractility in the actin cytoskeleton. The resulting force acts back to the
sites of adhesion, resulting in a positive feedback loop for mature adhesion.
Here we model this biochemical-mechanical feedback loop for the special case
when the actin cytoskeleton is organized in stress fibers, which are
contractile bundles of actin filaments. Activation of myosin II molecular
motors through the Rho-pathway is described by a system of reaction-diffusion
equations, which are coupled into a viscoelastic model for a contractile actin
bundle. We find strong spatial gradients in the activation of contractility and
in the corresponding deformation pattern of the stress fiber, in good agreement
with experimental findings.


title:
Observations of interior whispering gallery modes in asymmetric optical
  resonators with rational caustics

abstract:
  We propose asymmetric resonant cavities with rational caustics and
experimentally demonstrate interior whispering gallery modes in monolithic
silicon mesoscopic microcavities. These microcavities demonstrate unique
robustness of cavity quality factor (Q) against roughness Rayleigh scattering.
Angle-resolved tapered fiber measurements and near-field images observe
distinct resonant families and asymmetric emission from interior whispering
gallery modes, which can be used for microcavity laser and CQED applications.


title:
Electroweak corrections to W-boson hadroproduction at finite transverse
  momentum

abstract:
  We calculate the full one-loop electroweak radiative corrections to the cross
section of single W-boson inclusive hadroproduction at finite transverse
momentum (p_T). This includes the O(alpha) corrections to W+j production, the
O(alpha_s) corrections to W+gamma production, and the tree-level contribution
from W+j photoproduction with one direct or resolved photon in the initial
state. We present the integrated cross section as a function of a minimum-p_T
cut as well as the p_T distribution for the experimental conditions at the
Fermilab Tevatron and the CERN LHC and estimate the theoretical uncertainties.


title: On C1-robust transitivity of volume-preserving flows

abstract:
  We prove that a divergence-free and C1-robustly transitive vector field has
no singularities. Moreover, if the vector field is C4 then the linear Poincare
flow associated to it admits a dominated splitting over M.


title:
Generalization of escape rate from a metastable state driven by external
  cross-correlated noise processes

abstract:
  We propose generalization of escape rate from a metastable state for
externally driven correlated noise processes in one dimension. In addition to
the internal non-Markovian thermal fluctuations, the external correlated noise
processes we consider are Gaussian, stationary in nature and are of
Ornstein-Uhlenbeck type. Based on a Fokker-Planck description of the effective
noise processes with finite memory we derive the generalized escape rate from a
metastable state in the moderate to large damping limit and investigate the
effect of degree of correlation on the resulting rate. Comparison of the
theoretical expression with numerical simulation gives a satisfactory agreement
and shows that by increasing the degree of external noise correlation one can
enhance the escape rate through the dressed effective noise strength.


title:
Study of Initial and Final State Effects in Ultrarelativistic Heavy Ion
  Collisions Using Hadronic Probes

abstract:
  It has been theorized that if heavy nuclei (e.g. Au, Pb) are collided at
sufficiently high energies, we might be to recreate the conditions that existed
in the universe a few microseconds after the Big Bang. The kinetic energy of
the colliding nuclei gets converted into heat, leading to a phase transition
into a new state of matter: the Quark-Gluon Plasma (QGP), in which quarks and
gluons are deconfined. However, we never directly get to see the QGP because as
the matter cools it recombines (hadronizes) into ordinary subatomic particles.
We can only hope to infer its existence from indirect experimental signatures,
after hadronization. In this dissertation we attempt to shed some light on:
  Properties of the final state of produced matter in Au+Au collisions at
$\sqrt{s_{NN}}=200$ GeV. As the hot, dense system of particles from the
collision zone cools and expands, light nuclei like deuterons and
anti-deuterons can be formed, with a probability proportional to the product of
the phase space densities of its constituent nucleons. Thus, invariant yield of
deuterons, compared to the protons and neutrons from which they coalesce,
provides information about the size of the emitting system and its space-time
evolution.
  The initial conditions that led to this. This is done by looking at the
nuclear modification factor $R_{cp}$ from particle production in forward and
backward directions in a ``control'' experiment using d+Au collisions at
$\sqrt{s_{NN}}=200$ GeV. This can allow us to distinguish between effects that
could potentially be due to deconfinement, versus effects of cold nuclear
matter.


title: Uniform estimates for cubic oscillatory integrals

abstract:
  This paper establishes the optimal decay rate for scalar oscillatory
integrals in $n$ variables which satisfy a nondegeneracy condition on the third
derivatives. The estimates proved are stable under small linear perturbations,
as encountered when computing the Fourier transform of surface-carried
measures. The main idea of the proof is to construct a nonisotropic family of
balls which locally capture the scales and directions in which cancellation
occurs.


title:
Faxen relations in solids - a generalized approach to particle motion in
  elasticity and viscoelasticity

abstract:
  A movable inclusion in an elastic material oscillates as a rigid body with
six degrees of freedom. Displacement/rotation and force/moment tensors which
express the motion of the inclusion in terms of the displacement and force at
arbitrary exterior points are introduced. Using reciprocity arguments two
general identities are derived relating these tensors. Applications of the
identities to spherical particles provide several new results, including simple
expressions for the force and moment on the particle due to plane wave
excitation.


title:
Recoil velocities from equal-mass binary black-hole mergers: a
  systematic investigation of spin-orbit aligned configurations

abstract:
  Binary black-hole systems with spins aligned with the orbital angular
momentum are of special interest, as studies indicate that this configuration
is preferred in nature. If the spins of the two bodies differ, there can be a
prominent beaming of the gravitational radiation during the late plunge,
causing a recoil of the final merged black hole. We perform an accurate and
systematic study of recoil velocities from a sequence of equal-mass black holes
whose spins are aligned with the orbital angular momentum, and whose individual
spins range from a = +0.584 to -0.584. In this way we extend and refine the
results of a previous study and arrive at a consistent maximum recoil of 448 +-
5 km/s for anti-aligned models as well as to a phenomenological expression for
the recoil velocity as a function of spin ratio. This relation highlights a
nonlinear behavior, not predicted by the PN estimates, and can be readily
employed in astrophysical studies on the evolution of binary black holes in
massive galaxies. An essential result of our analysis is the identification of
different stages in the waveform, including a transient due to lack of an
initial linear momentum in the initial data. Furthermore we are able to
identify a pair of terms which are largely responsible for the kick, indicating
that an accurate computation can be obtained from modes up to l=3. Finally, we
provide accurate measures of the radiated energy and angular momentum, finding
these to increase linearly with the spin ratio, and derive simple expressions
for the final spin and the radiated angular momentum which can be easily
implemented in N-body simulations of compact stellar systems. Our code is
calibrated with strict convergence tests and we verify the correctness of our
measurements by using multiple independent methods whenever possible.


title: Red Density Perturbations and Inflationary Gravitational Waves

abstract:
  We study the implications of recent indications for a red spectrum of
primordial density perturbations for the detection of inflationary
gravitational waves (IGWs) with forthcoming cosmic microwave background
experiments. We find that if inflation occurs with a single field with an
inflaton potential minimized at V=0, then Planck will be able to detect IGWs at
better than 2$\sigma$ confidence level, unless the inflaton potential is a
power law with a very weak power. The proposed satellite missions of the Cosmic
Vision and Inflation Probe programs will be able to detect IGWs from all the
models we have surveyed at better than 5$\sigma$ confidence level. We provide
an example of what is required if the IGW background is to remain undetected
even by these latter experiments.


title:
Atomic-scale structure of the SrTiO3(001)-c(6x2) reconstruction:
  Experiments and first-principles calculations

abstract:
  The c(6x2) is a reconstruction of the SrTiO3(001) surface that is formed
between 1050-1100oC in oxidizing annealing conditions. This work proposes a
model for the atomic structure for the c(6x2) obtained through a combination of
results from transmission electron diffraction, surface x-ray diffraction,
direct methods analysis, computational combinational screening, and density
functional theory. As it is formed at high temperatures, the surface is complex
and can be described as a short-range ordered phase featuring microscopic
domains composed of four main structural motifs. Additionally, non-periodic
TiO2 units are present on the surface. Simulated scanning tunneling microscopy
images based on the electronic structure calculations are consistent with
experimental images.


title: A Characterisation of First-Order Constraint Satisfaction Problems

abstract:
  We describe simple algebraic and combinatorial characterisations of finite
relational core structures admitting finitely many obstructions. As a
consequence, we show that it is decidable to determine whether a constraint
satisfaction problem is first-order definable: we show the general problem to
be NP-complete, and give a polynomial-time algorithm in the case of cores. A
slight modification of this algorithm provides, for first-order definable
CSP's, a simple poly-time algorithm to produce a solution when one exists. As
an application of our algebraic characterisation of first order CSP's, we
describe a large family of L-complete CSP's.


title: Stability for large forbidden subgraphs

abstract:
  We extend the classical stability theorem of Erdos and Simonovits for
forbidden graphs of logarithmic order.


title: Renormalizable 1/N_f Expansion for Field Theories in Extra Dimensions

abstract:
  We demonstrate how one can construct renormalizable perturbative expansion in
formally nonrenormalizable higher dimensional field theories. It is based on
$1/N_f$-expansion and results in a logarithmically divergent perturbation
theory in arbitrary high space-time dimension. First, we consider a simple
example of $N$-component scalar filed theory and then extend this approach to
Abelian and non-Abelian gauge theories with $N_f$ fermions. In the latter case,
due to self-interaction of non-Abelian fields the proposed recipe requires some
modification which, however, does not change the main results. The resulting
effective coupling is dimensionless and is running in accordance with the usual
RG equations. The corresponding beta function is calculated in the leading
order and is nonpolynomial in effective coupling. It exhibits either UV
asymptotically free or IR free behaviour depending on the dimension of
space-time. The original dimensionful coupling plays a role of a mass and is
also logarithmically renormalized. We analyze also the analytical properties of
a resulting theory and demonstrate that in general it acquires several ghost
states with negative and/or complex masses. In the former case, the ghost state
can be removed by a proper choice of the coupling. As for the states with
complex conjugated masses, their contribution to physical amplitudes cancels so
that the theory appears to be unitary.


title:
Anomalous Hall effect for the phonon heat conductivity in paramagnetic
  dielectric

abstract:
  The theory of anomalous Hall effect for the heat transfer in a paramagnetic
dielectric, discovered experimentally in [1], is developed. The appearance of
the phonon heat flux normal to both the temperature gradient and the magnetic
field is connected with the interaction of magnetic ions with the crystal field
oscillations. In crystals with an arbitrary phonon spectrum this interaction
creates the elliptical polarization of phonons. The kinetics related to phonon
scattering induced by the spin-phonon interaction determines an origin of the
off-diagonal phonon density matrix. The combination of the both factors is
decisive for the phenomenon under consideration.


title:
The environments and clustering properties of 2dFGRS-selected starburst
  galaxies

abstract:
  We investigate the environments and clustering properties of starburst
galaxies selected from the 2dF Galaxy Redshift Survey (2dFGRS) in order to
determine which, if any, environmental factors play a role in triggering a
starburst. We quantify the local environments, clustering properties and
luminosity functions of our starburst galaxies and compare to random control
samples. The starburst galaxies are also classified morphologically in terms of
their broad Hubble type and evidence of tidal merger/interaction signatures. We
find the starburst galaxies to be much less clustered on large (5-15 Mpc)
scales compared to the overall 2dFGRS galaxy population. In terms of their
environments, we find just over half of the starburst galaxies to reside in low
to intermediate luminosity groups, and a further ~30 per cent residing in the
outskirts and infall regions of rich clusters. Their luminosity functions also
differ significantly from that of the overall 2dFGRS galaxy population, with
the sense of the difference being critically dependent on the way their star
formation rates are measured. In terms of pin-pointing what might trigger the
starburst, it would appear that factors relating to their local environment are
most germane. Specifically, we find clear evidence that the presence of a near
neighbour of comparable luminosity/mass within 20 kpc is likely to be important
in triggering a starburst. We also find that a significant fraction (20-30 per
cent) of our starburst galaxies have morphologies indicative of either an
ongoing or recent tidal interaction and/or merger. These findings
notwithstanding, there remain a significant portion of starburst galaxies where
local environmental influences are not in any obvious way playing a triggering
role, leading us to conclude that starbursts can also be internally driven.


title:
Searches for Direct Pair Production of Supersymmetric Top and
  Supersymmetric Bottom Quarks in p-pbar Collisions at sqrt(s)=1.96 TeV

abstract:
  We search for direct pair production of supersymmetric top quarks and
supersymmetric bottom quarks in proton-antiproton collisions at sqrt(s)=1.96
TeV, using 295 pb^-1 of data recorded by the Collider Detector at Fermilab (CDF
II) experiment. The supersymmetric top (supersymmetric bottom) quarks are
selected by reconstructing their decay into a charm (bottom) quark and a
neutralino, which is assumed to be the lightest supersymmetric particle. The
signature of such processes is two energetic heavy-flavor jets and missing
transverse energy. The number of events that pass our selection for each search
process is consistent with the expected standard model background. By comparing
our results to the theoretical production cross sections of the supersymmetric
top and supersymmetric bottom quarks in the minimal supersymmetric standard
model, we exclude, at a 95% confidence level in the frame of that model, a
supersymmetric top quark mass up to 132 GeV/c^2 for a neutralino mass of 48
GeV/c^2, and a supersymmetric bottom quark mass up to 193 GeV/c^2 for a
neutralino mass of 40 GeV/c^2.


title:
Logarithmic geometry, minimal free resolutions and toric algebraic
  stacks

abstract:
  In this paper we will introduce a certain type of morphisms of log schemes
(in the sense of Fontaine, Illusie, and Kato) and investigate their moduli.
Then by applying this we define a notion of toric algebraic stacks over
arbitrary schemes, which may be regarded as torus embeddings within the
framework of algebraic stacks, and study some basic properties. Furthermore, we
study the stack-theoretic analogue of toroidal embeddings.


title:
A Particle-Particle, Particle-Density (P3D) algorithm for the
  calculation of electrostatic interactions of particles with slab-like
  geometry

abstract:
  We present a fast and accurate method to calculate the electrostatic energy
and forces of interacting particles with the boundary conditions appropriate to
surfaces, i.e periodic in the two directions parallel to the surface and free
in the perpendicular direction. In the spirit of the Ewald method the problem
is divided into a short range and long range part. The charge density
responsible for the long range part is represented by plane waves in the
periodic directions and by finite elements in the non-periodic direction. Our
method has computational complexity of O(N_g log(N_g)) with a very small
prefactor, where N_g is the number of grid points.


title:
Evaluation of effective resistances in pseudo-distance-regular resistor
  networks

abstract:
  In Refs.[1] and [2], calculation of effective resistances on distance-regular
networks was investigated, where in the first paper, the calculation was based
on the stratification of the network and Stieltjes function associated with the
network, whereas in the latter one a recursive formula for effective
resistances was given based on the Christoffel-Darboux identity. In this paper,
evaluation of effective resistances on more general networks called
pseudo-distance-regular networks [21] or QD type networks \cite{obata} is
investigated, where we use the stratification of these networks and show that
the effective resistances between a given node such as $\alpha$ and all of the
nodes $\beta$ belonging to the same stratum with respect to $\alpha$
($R_{\alpha\beta^{(m)}}$, $\beta$ belonging to the $m$-th stratum with respect
to the $\alpha$) are the same. Then, based on the spectral techniques, an
analytical formula for effective resistances $R_{\alpha\beta^{(m)}}$ such that
$L^{-1}_{\alpha\alpha}=L^{-1}_{\beta\beta}$ (those nodes $\alpha$, $\beta$ of
the network such that the network is symmetric with respect to them) is given
in terms of the first and second orthogonal polynomials associated with the
network, where $L^{-1}$ is the pseudo-inverse of the Laplacian of the network.
  From the fact that in distance-regular networks,
$L^{-1}_{\alpha\alpha}=L^{-1}_{\beta\beta}$ is satisfied for all nodes
$\alpha,\beta$ of the network, the effective resistances
$R_{\alpha\beta^{(m)}}$ for $m=1,2,...,d$ ($d$ is diameter of the network which
is the same as the number of strata) are calculated directly, by using the
given formula.


title:
Dynamical and energetic instabilities in multi-component Bose-Einstein
  condensates in optical lattices

abstract:
  We study dynamical and energetic instabilities in the transport properties of
Bloch waves for atomic multi-component Bose-Einstein condensates in optical
lattices in the tight-binding limit. We obtain stability criteria analytically,
as a function of superfluid velocities and interaction parameters, in several
cases for two-component and spinor condensates. In the two-species case we find
that the presence of the other condensate component can stabilize the
superfluid flow of an otherwise unstable condensate and that the free space
dynamical miscibility condition of the two species can be reversed by tuning
the superfluid flow velocities. In spin-1 condensates, we find the steady-state
Bloch wave solutions and characterize their stability criteria. We find
generally more regions of dynamical instability arise for the polar than for
the ferromagnetic solutions. In the presence of magnetic Zeeman shifts, we find
a richer variety of condensate solutions and find that the linear Zeeman shift
can stabilize the superfluid flow in several cases of interest.


title: Noise effects in extended chaotic system: study on the Lorenz'96 model

abstract:
  We investigate the effects of a time-correlated noise on an extended chaotic
system. The chosen model is the Lorenz'96, a kind of toy model used for climate
studies. The system is subjected to both temporal and spatiotemporal
perturbations. Through the analysis of the system's time evolution and its time
correlations, we have obtained numerical evidence for two stochastic
resonance-like behaviors. Such behavior is seen when a generalized
signal-to-noise ratio function are depicted as a function of the external noise
intensity or as function of the system size. The underlying mechanism seems to
be associated to a noise-induced chaos reduction. The possible relevance of
those findings for an optimal climate prediction are discussed, using an
analysis of the noise effects on the evolution of finite perturbations and
errors.

categories: nlin.CD cond-mat.stat-mech nlin.PS physics.ao-ph


title: Model for curvature-driven pearling instability in membranes

abstract:
  A phase-field model for dealing with dynamic instabilities in membranes is
presented. We use it to study curvature-driven pearling instability in vesicles
induced by the anchorage of amphiphilic polymers on the membrane. Within this
model, we obtain the morphological changes reported in recent experiments. The
formation of a homogeneous pearled structure is achieved by consequent pearling
of an initial cylindrical tube from the tip. For high enough concentration of
anchors, we show theoretically that the homogeneous pearled shape is
energetically less favorable than an inhomogeneous one, with a large sphere
connected to an array of smaller spheres.


title: Is a gas of strongly interacting atomic fermions a nearly perfect fluid?

abstract:
  We use all-optical methods to produce a highly-degenerate Fermi gas of
spin-1/2 $^6$Li atoms. A magnetic field tunes the gas near a collisional
(Feshbach) resonance, producing strong interactions between spin-up and
spin-down atoms. This atomic gas is a paradigm for strong interactions in
nature, and provides tests of current quantum many-body calculational methods
for diverse systems, including very high temperature superconductors, nuclear
matter in neutron stars, and the quark-gluon plasma of the Big Bang. We have
measured properties of a breathing mode over a wide range of temperatures. At
temperatures both below and well above the superfluid transition, the frequency
of the mode is nearly constant and very close to the hydrodynamic value.
However, explaining both the frequency and the damping rate in the normal
collisional regime has not been achieved. Our measurements of the damping rate
as a function of the energy of the gas are used to estimate an upper bound on
the viscosity. Using our new measurements of the entropy of the gas, we
estimate the ratio of the shear viscosity to the entropy density, and compare
the result with the lower bound for quantum viscosity recently predicted using
string theory methods.


title:
Electric-field-induced displacement of a charged spherical colloid
  embedded in an elastic Brinkman medium

abstract:
  When an electric field is applied to an electrolyte-saturated polymer gel
embedded with charged colloidal particles, the force that must be exerted by
the hydrogel on each particle reflects a delicate balance of electrical,
hydrodynamic and elastic stresses. This paper examines the displacement of a
single charged spherical inclusion embedded in an uncharged hydrogel. We
present numerically exact solutions of coupled electrokinetic transport and
elastic-deformation equations, where the gel is treated as an incompressible,
elastic Brinkman medium. This model problem demonstrates how the displacement
depends on the particle size and charge, the electrolyte ionic strength, and
Young's modulus of the polymer skeleton. The numerics are verified, in part,
with an analytical (boundary-layer) theory valid when the Debye length is much
smaller than the particle radius. Further, we identify a close connection
between the displacement when a colloid is immobilized in a gel and its
velocity when dispersed in a Newtonian electrolyte. Finally, we describe an
experiment where nanometer-scale displacements might be accurately measured
using back-focal-plane interferometry. The purpose of such an experiment is to
probe physicochemical and rheological characteristics of hydrogel composites,
possibly during gelation.


title: A note on the incidence coloring of outerplanar graphs

abstract:
  A proof that every outerplanar graph is \Delta+2 colorable. This is slightly
stronger then an unpublished result of Wang Shudong, Ma Fangfang, Xu Jin, and
Yan Lijun proving the same for 2-connected outerplanar graphs.


title:
Age-Rotation-Activity Relations for M Dwarf Stars Based on ASAS
  Photometric Data

abstract:
  Based on analysis of photometric observations of nearby M type stars obtained
with ASAS, 31 periodic variables were detected. The determined periods are
assumed to be related to rotation periods of the investigated stars. Among them
10 new variables with periods longer than 10 days were found, which brings the
total number of slowly rotating M stars with known rotation periods to 12
objects.
  X-ray activity and rotation evolution of M stars follows the trends observed
in G-K type stars. Rapidly rotating stars are very active and activity
decreases with increasing rotation period but the period-activity relation is
mass-dependent which suggests that the rotation period alone is not a proper
measure of activity. The investigated stars were grouped according to their
mass and the empirical turnover time was determined for each group. It
increases with decreasing mass more steeply than for K type stars for which a
flat dependence had been found. The resulting Rossby number-activity relation
shows an exponential decrease of activity with increasing Rossby number.
  The analysis of space motions of 27 single stars showed that all rapidly
rotating and a few slowly rotating stars belong to young disk (YD) whereas all
old disk (OD) stars are slowly rotating. The median rotation period of YD stars
is about 2 days and that of OD stars is equal to 47 days, i.e. nearly 25 times
longer. The average X-ray flux of OD stars is about 1.7 dex lower than YD stars
in a good agreement with the derived Rossby number-activity formula
supplemented with rotation-age relation and in a fair agreement with recent
observations but in a disagreement with the Skumanich formula supplemented with
the activity-rotation relation.


title: Weak convergence of CD kernels and applications

abstract:
  We prove a general result on equality of the weak limits of the zero counting
measure, $d\nu_n$, of orthogonal polynomials (defined by a measure $d\mu$) and
$\frac{1}{n} K_n(x,x) d\mu(x)$. By combining this with Mate--Nevai and Totik
upper bounds on $n\lambda_n(x)$, we prove some general results on $\int_I
\frac{1}{n} K_n(x,x) d\mu_s\to 0$ for the singular part of $d\mu$ and $\int_I
|\rho_E(x) - \frac{w(x)}{n} K_n(x,x)| dx\to 0$, where $\rho_E$ is the density
of the equilibrium measure and $w(x)$ the density of $d\mu$.


title:
Dynamical invariants and nonadiabatic geometric phases in open quantum
  systems

abstract:
  We introduce an operational framework to analyze non-adiabatic Abelian and
non-Abelian, cyclic and non-cyclic, geometric phases in open quantum systems.
In order to remove the adiabaticity condition, we generalize the theory of
dynamical invariants to the context of open systems evolving under arbitrary
convolutionless master equations. Geometric phases are then defined through the
Jordan canonical form of the dynamical invariant associated with the
super-operator that governs the master equation. As a by-product, we provide a
sufficient condition for the robustness of the phase against a given decohering
process. We illustrate our results by considering a two-level system in a
Markovian interaction with the environment, where we show that the
non-adiabatic geometric phase acquired by the system can be constructed in such
a way that it is robust against both dephasing and spontaneous emission.


title: Optimization of Apodized Pupil Lyot Coronagraph for ELTs

abstract:
  We study the optimization of the Apodized Pupil Lyot Coronagraph (APLC) in
the context of exoplanet imaging with ground-based telescopes. The APLC
combines an apodization in the pupil plane with a small Lyot mask in the focal
plane of the instrument. It has been intensively studied in the literature from
a theoretical point of view, and prototypes are currently being manufactured
for several projects. This analysis is focused on the case of Extremely Large
Telescopes, but is also relevant for other telescope designs.
  We define a criterion to optimize the APLC with respect to telescope
characteristics like central obscuration, pupil shape, low order segment
aberrations and reflectivity as function of the APLC apodizer function and mask
diameter. Specifically, the method was applied to two possible designs of the
future European-Extremely Large Telescope (E-ELT).
  Optimum configurations of the APLC were derived for different telescope
characteristics. We show that the optimum configuration is a stronger function
of central obscuration size than of other telescope parameters. We also show
that APLC performance is quite insensitive to the central obscuration ratio
when the APLC is operated in its optimum configuration, and demonstrate that
APLC optimization based on throughput alone is not appropriate.


title:
Electric-field-enhanced transport in polyacrylamide hydrogel
  nano-composites

abstract:
  Electroosmotic pumping through uncharged hydrogels can be achieved by
embedding the polymer network with charged colloidal inclusions. Matos and
co-workers (2006) recently used the concept to enhance the diffusion-limited
flux of uncharged molecules across polyacrylamide hydrogel membraness for the
purpose of improving the performance of biosensors. This paper seeks to link
their reported macroscale diagnostics to physicochemical characteristics of the
composite microstructure. A mathematical model for the bulk electroosmotically
enhanced tracer flux is proposed, which is combined with the electrokinetic
model to ascertain the electroosmotic pumping velocity from measured flux
enhancements. Because the experiments are performed with a known current
density, but unknown bulk conductivity and electric field strength, theoretical
estimates of the bulk electrical conductivity are adopted. These account for
nano-particle polarization, added counterions, and non-specific adsorption.
Theoretical predictions of the flux enhancement, achieved without any fitting
parameters, are within a factor of two of the experiments. Alternatively, if
the Brinkman screening length of the polymer skeleton is treated as a fitting
parameter, then the best-fit values are bounded by the range 0.9-1.6 nm,
depending on the inclusion size and volume fraction. Independent
pressure-driven flow experiments reported in the literature for polyacrylamide
gels without inclusions suggest 0.4 or 0.8 nm. The comparison can be improved
by allowing for hindered ion migration, while uncertainties regarding the
inclusion surface charge are demonstrated to have a negligible influence on the
electroosmotic flow.


title:
Monte Carlo simulation of uncoupled continuous-time random walks
  yielding a stochastic solution of the space-time fractional diffusion
  equation

abstract:
  We present a numerical method for the Monte Carlo simulation of uncoupled
continuous-time random walks with a Levy alpha-stable distribution of jumps in
space and a Mittag-Leffler distribution of waiting times, and apply it to the
stochastic solution of the Cauchy problem for a partial differential equation
with fractional derivatives both in space and in time. The one-parameter
Mittag-Leffler function is the natural survival probability leading to
time-fractional diffusion equations. Transformation methods for Mittag-Leffler
random variables were found later than the well-known transformation method by
Chambers, Mallows, and Stuck for Levy alpha-stable random variables and so far
have not received as much attention; nor have they been used together with the
latter in spite of their mathematical relationship due to the geometric
stability of the Mittag-Leffler distribution. Combining the two methods, we
obtain an accurate approximation of space- and time-fractional diffusion
processes almost as easy and fast to compute as for standard diffusion
processes.


title: The Eternal Sunshine of the Spotless Mind

abstract:
  We extend the worldline measure for pocket formation in eternal inflation to
allow for time-ordered bubble formation. Such a time-ordering is equivalent to
imposing a preferred time-slicing on the "parent" de Sitter space. Using this
measure, we describe a covariant version of the youngness paradox and show that
the youngness paradox is a gauge artifact if the parent spacetime is an
unbroken de Sitter space, due to the lack of an explicit time-ordering for the
bubble nucleation events. We then show that one can add a "clock" to the de
Sitter space, in the form of a vector field with a spontaneously broken
symmetry that defines a unique timelike direction accessible to all observers.
Once this is done, the existence of a preferred slicing means that the
youngness paradox cannot be easily resolved. We use this to elucidate the
apparent "persistence of memory" discussed recently by Garriga, Guth and
Vilenkin, for inflationary universes produced by bubble nucleation.


title: Six Conjectures which Generalize or Are Related to Andrica's Conjecture

abstract:
  Six conjectures on pairs of consecutive primes are listed in this paper,
together with examples for each case.


title: Derived completions in stable homotopy theory

abstract:
  We construct a notion of derived completion which applies to homomorphisms of
commutative S-algebras. We study the relationship of the construction with
other constructions of completions, and prove various invariance properties.
The construction is expected to have applications within algebraic K-theory.


title:
Effect of suppressed excitation on the amplitude distribution of 5-min
  oscillations in sunspots

abstract:
  Five-minute oscillations on the Sun (acoustic and surface gravity waves) are
excited by subsurface turbulent convection. However, in sunspots the excitation
is suppressed because strong magnetic field inhibits convection. We use 3D
simulations to investigate how the suppression of excitation sources affects
the distribution of the oscillation power in sunspot regions. The amplitude of
random acoustic sources was reduced in circular-shaped regions to simulate the
suppression in sunspots. The simulation results show that the amplitude of the
oscillations can be approximately 2-4 times lower in the sunspot regions in
comparison to the quiet Sun, just because of the suppressed sources. Using
SOHO/MDI data we measured the amplitude ratio for the same frequency bands
outside and inside sunspots, and found that this ratio is approximately 3-4.
Hence, the absence of excitation sources inside sunspots makes a significant
contribution (about 50% or higher) to the observed amplitude ratio and must be
taken into account in sunspot seismology.


title: The Shared Reward Dilemma

abstract:
  One of the most direct human mechanisms of promoting cooperation is rewarding
it. We study the effect of sharing a reward among cooperators in the most
stringent form of social dilemma, namely the Prisoner's Dilemma. Specifically,
for a group of players that collect payoffs by playing a pairwise Prisoner's
Dilemma game with their partners, we consider an external entity that
distributes a fixed reward equally among all cooperators. Thus, individuals
confront a new dilemma: on the one hand, they may be inclined to choose the
shared reward despite the possibility of being exploited by defectors; on the
other hand, if too many players do that, cooperators will obtain a poor reward
and defectors will outperform them. By appropriately tuning the amount to be
shared a vast variety of scenarios arises, including traditional ones in the
study of cooperation as well as more complex situations where unexpected
behavior can occur. We provide a complete classification of the equilibria of
the $n$-player game as well as of its evolutionary dynamics.


title: Formation of superheavy nuclei in cold fusion reactions

abstract:
  Within the concept of the dinuclear system (DNS), a dynamical model is
proposed for describing the formation of superheavy nuclei in complete fusion
reactions by incorporating the coupling of the relative motion to the nucleon
transfer process. The capture of two heavy colliding nuclei, the formation of
the compound nucleus and the de-excitation process are calculated by using an
empirical coupled channel model, solving a master equation numerically and
applying statistical theory, respectively. Evaporation residue excitation
functions in cold fusion reactions are investigated systematically and compared
with available experimental data. Maximal production cross sections of
superheavy nuclei in cold fusion reactions with stable neutron-rich projectiles
are obtained. Isotopic trends in the production of the superheavy elements
Z=110, 112, 114, 116, 118 and 120 are analyzed systematically. Optimal
combinations and the corresponding excitation energies are proposed.


title:
Determination of the strong coupling constant from the CLEO measurement
  of the total hadronic cross section in $e^+e^-$ annihilation below 10.56 GeV

abstract:
  Using recent CLEO III results for the cross section for $e^+e^- \to {\rm
hadrons}$ at seven centre-of-mass energies between 6.964 and 10.538 GeV, we
derive a value for the strong coupling constant
$\alpha_s(M_Z^2)=0.110_{-0.012}^{-0.010}{}_{-0.011}^{+0.010}$ where the
uncertainties are uncorrelated and correlated, respectively. Our result differs
significantly from the one derived by CLEO III, as a consequence of inclusion
of quark mass effects and the proper matching between the effective theories
with four and five flavours. Combining this new result with an analysis based
on earlier cross section measurements in the energy region between 2 and 10.6
GeV, we obtain $\alpha_s(M_Z^2)=0.119^{+0.009}_{-0.011}$, well consistent with
the current world average.


title: General Covariant Gauge Fixing for Massless Spin-Two Fields

abstract:
  The most general covariant gauge fixing Lagrangian is considered for a
spin-two gauge theory in the context of the Faddeev-Popov procedure. In
general, five parameters characterize this gauge fixing. Certain limiting
values for these parameters give rise to a spin-two propagator that is either
traceless or transverse, but for no values of these parameters is this
propagator simultaneously traceless and transverse. Having a
traceless-transverse (TT) propagator ensures that only the physical degrees of
freedom associated with the tensor field propagate, and hence it is analogous
to the Landau gauge in electrodynamics. To obtain such a traceless-transverse
propagator, a gauge fixing Lagrangian which is not quadratic must be employed;
this sort of gauge fixing Lagrangian is not encountered in the usual
Faddeev-Popov procedure. It is shown that when this non-quadratic gauge fixing
Lagrangian is used, two Fermionic and one Bosonic ghost arise. As a simple
application we discuss the energy-momentum tensor of the gravitational field at
finite temperature.


title: An Elementary Proof of the Fundamental Theorem of Tropical Algebra

abstract:
  In this paper we give an elementary proof of the Fundamental Theorem of
Algebra for polynomials over the rational tropical semi-ring. We prove that,
tropically, the rational numbers are algebraically closed. We provide a simple
algorithm for factoring tropical polynomials of a single variable. A central
idea is the concept of least-coefficient polynomials as representatives for
classes of functionally equivalent polynomials. This idea has importance far
beyond the proof of the Fundamental Theorem of Tropical Algebra.


title: The Fermat-Torricelli problem in normed planes and spaces

abstract:
  We investigate the Fermat-Torricelli problem in d-dimensional real normed
spaces or Minkowski spaces, mainly for d=2. Our approach is to study the
Fermat-Torricelli locus in a geometric way. We present many new results, as
well as give an exposition of known results that are scattered in various
sources, with proofs for some of them. Together, these results can be
considered to be a minitheory of the Fermat-Torricelli problem in Minkowski
spaces and especially in Minkowski planes. This demonstrates that substantial
results about locational problems valid for all norms can be found using a
geometric approach.


title: Many lives in many worlds

abstract:
  I argue that accepting quantum mechanics to be universally true means that
you should also believe in parallel universes. I give my assessment of
Everett's theory as it celebrates its 50th anniversary.


title:
A New Constraint on the Escape Fraction in Distant Galaxies Using
  Gamma-ray Burst Afterglow Spectroscopy

abstract:
  We describe a new method to measure the escape fraction fesc of ionizing
radiation from distant star-forming galaxies using the afterglow spectra of
long-duration gamma-ray bursts (GRBs). Optical spectra of GRB afterglows allow
us to evaluate the optical depth of the host ISM, according to the neutral
hydrogen column density N(HI) observed along the sightlines toward the
star-forming regions where the GRBs are found. Different from previous effort
in searching for faint, transmitted Lyman continuum photons, our method is not
subject to background subtraction uncertainties and does not require prior
knowledge of either the spectral shape of the host galaxy population or the IGM
Lya forest absorption along these GRB sightlines. Because most GRBs occur in
sub-L_* galaxies, our study also offers the first constraint on fesc for
distant low-mass galaxies that dominate the cosmic luminosity density. We have
compiled a sample of 27 GRBs at redshift z>2 for which the underlying N(HI) in
the host ISM are known. These GRBs together offer a statistical sampling of the
integrated optical depth to ionizing photons along random sightlines from
star-forming regions in the host galaxies, and allow us to estimate the mean
escape fraction <fesc> averaged over different viewing angles. We find
<fesc>=0.02\pm 0.02 and place a 95% c.l. upper limit <fesc> <= 0.075 for these
hosts. We discuss possible biases of our approach and implications of the
result. Finally, we propose to extend this technique for measuring <fesc> at
z~0.2 using spectra of core-collapse supernovae.


title:
Mechanisms of Diffusional Nucleation of Nanocrystals and Their
  Self-Assembly into Uniform Colloids

abstract:
  We survey our research on modeling the mechanisms of control of uniformity in
growth of nanosize and colloid particles. The former are produced as
nanocrystals, by burst-nucleation from solution. The latter, colloid-size
particles, are formed by self-assembly (aggregation) of the nanocrystals. In
the colloid particle synthesis, the two dynamical processes are coupled, and
both are governed by diffusional transport of the respective building blocks
(monomers). The interrelation of the two processes allows for synthesis of
narrow size distribution colloid dispersions which are of importance in many
applications.
  We first review a mathematical model of diffusive cluster growth by capture
of monomer "singlets." Burst nucleation of nanoparticles in solution is then
analyzed. Finally, we couple it to the secondary process of aggregation of
nanoparticles to form colloids, and we discuss various aspects of the modeling
of particle size distribution, as well as other features of the processes
considered.

categories: cond-mat.soft cond-mat.dis-nn cond-mat.mtrl-sci cond-mat.stat-mech


title:
Effect of triple interaction on energy delocalization in the strongly
  disordered system of interacting two-level defects

abstract:
  We accurately treat the effect of the double and triple interactions of
two-level systems (TLS) in glasses onto the energy delocalization due to the
long-range interaction of TLS. Although this work qualitatively reproduces the
estimates of our previous work we believe that it is important because in this
paper the estimates are done with quantitative accuracy. This work can serve as
the important step towards the development of quantitative theory of many-body
delocalization due to the long-range interaction. Our study is compared with
the recent work by Bodea et al claiming that the interaction of TLS triples
leads to the energy delocalization. We cannot agree with the mentioned work
because as we show the interaction of TLS triples was overestimated there and
therefore the result for the TLS relaxation rate obtained there is invalid.


title: Rapidly varying accretion and AGN feedback

abstract:
  Accretion rates onto AGN are likely to be extremely variable on short
timescales; much shorter than the typical cooling time of X-ray emitting gas in
elliptical galaxies and galaxy clusters. Using the Langevin approach it is
shown that, for a simple feedback system, this can induce variability in the
AGN power output that is of much larger amplitude, and persists for longer
timescales, than the initial fluctuations. An implication of this is that rich
galaxy clusters are expected to show the largest and longest-lived
fluctuations. Stochastic variations in the accretion rate also mean that the
AGN injects energy across a wide range of timescales. This allows the AGN to
maintain a much closer balance with its surroundings than if it was
periodically activated. The possible non-linear correlation between Bondi
accretion rate and jet power, found by Allen et al 2006, can be explained if
the instantaneous accretion rate, scaled by jet power, varies log-normally.
This explanation also implies that the duty cycle of AGN activity increases
with the radiative losses of the surroundings, in qualitative agreement with
Best et al 2005.