title: Glueball matrix elements: a lattice calculation and applications

abstract:
  We compute the matrix elements of the energy-momentum tensor between glueball
states and the vacuum in SU(3) lattice gauge theory and extrapolate them to the
continuum. These matrix elements may play an important phenomenological role in
identifying glue-rich mesons. Based on a relation derived long ago by the ITEP
group for J/psi radiative decays, the scalar matrix element leads to a
branching ratio for the glueball that is at least three times larger than the
experimentally observed branching ratio for the f_0 mesons above 1GeV. This
suggests that the glueball component must be diluted quite strongly among the
known scalar mesons. Finally we review the current best continuum determination
of the scalar and tensor glueball masses, the deconfining temperature, the
string tension and the Lambda parameter, all in units of the Sommer reference
scale, using calculations based on the Wilson action.


title:
Lattice Properties of PbX (X = S, Se, Te): Experimental Studies and ab
  initio Calculations Including Spin-Orbit Effects

abstract:
  During the past five years the low temperature heat capacity of simple
semiconductors and insulators has received renewed attention. Of particular
interest has been its dependence on isotopic masses and the effect of spin-
orbit coupling in ab initio calculations. Here we concentrate on the lead
chalcogenides PbS, PbSe and PbTe. These materials, with rock salt structure,
have different natural isotopes for both cations and anions, a fact that allows
a systematic experimental and theoretical study of isotopic effects e.g. on the
specific heat. Also, the large spin-orbit splitting of the 6p electrons of Pb
and the 5p of Te allows, using a computer code which includes spin-orbit
interaction, an investigation of the effect of this interaction on the phonon
dispersion relations and the temperature dependence of the specific heat and on
the lattice parameter. It is shown that agreement between measurements and
calculations significantly improves when spin-orbit interaction is included.


title:
A Sample of Very Young Field L Dwarfs and Implications for the Brown
  Dwarf "Lithium Test" at Early Ages

abstract:
  Using a large sample of optical spectra of late-type dwarfs, we identify a
subset of late-M through L field dwarfs that, because of the presence of
low-gravity features in their spectra, are believed to be unusually young. From
a combined sample of 303 field L dwarfs, we find observationally that
7.6+/-1.6% are younger than 100 Myr. This percentage is in agreement with
theoretical predictions once observing biases are taken into account. We find
that these young L dwarfs tend to fall in the southern hemisphere (Dec < 0 deg)
and may be previously unrecognized, low-mass members of nearby, young
associations like Tucana-Horologium, TW Hydrae, beta Pictoris, and AB Doradus.
We use a homogeneously observed sample of roughly one hundred and fifty
6300-10000 Angstrom spectra of L and T dwarfs taken with the Low-Resolution
Imaging Spectrometer at the W. M. Keck Observatory to examine the strength of
the 6708-A Li I line as a function of spectral type and further corroborate the
trends noted by Kirkpatrick et al. (2000). We use our low-gravity spectra to
investigate the strength of the Li I line as a function of age. The data weakly
suggest that for early- to mid-L dwarfs the line strength reaches a maximum for
a few 100 Myr, whereas for much older (few Gyr) and much younger (<100 Myr) L
dwarfs the line is weaker or undetectable. We show that a weakening of lithium
at lower gravities is predicted by model atmosphere calculations, an effect
partially corroborated by existing observational data. Larger samples
containing L dwarfs of well determined ages are needed to further test this
empirically. If verified, this result would reinforce the caveat first cited in
Kirkpatrick et al. (2006) that the lithium test should be used with caution
when attempting to confirm the substellar nature of the youngest brown dwarfs.


title:
On the accuracy of DFT exchange-correlation functionals for H bonds in
  small water clusters II: The water hexamer and van der Waals interactions

abstract:
  Second order Moeller-Plesset perturbation theory (MP2) at the complete basis
set (CBS) limit and diffusion quantum Monte Carlo (DMC) are used to examine
several low energy isomers of the water hexamer. Both approaches predict the
so-called "prism" to be the lowest energy isomer, followed by "cage", "book",
and "cyclic" isomers. The energies of the four isomers are very similar, all
being within 10-15 meV/H2O. This reference data is then used to evaluate the
performance of several density-functional theory (DFT) exchange-correlation
(xc) functionals. A subset of the xc functionals tested for smaller water
clusters [I: Santra et al., J. Chem. Phys. 127, 184104 (2007)] has been
considered. Whilst certain functionals do a reasonable job at predicting the
absolute dissociation energies of the various isomers (coming within 10-20
meV/H2O), none predict the correct energetic ordering of the four isomers, nor
does any predict the correct low total energy isomer. All xc functionals tested
either predict the book or cyclic isomers to have the largest dissociation
energies. A many-body decomposition of the total interaction energies within
the hexamers leads to the conclusion that the failure lies in the poor
description of van der Waals (dispersion) forces in the xc functionals
considered. It is shown that the addition of an empirical pairwise (attractive)
C6/R6 correction to certain functionals allows for an improved energetic
ordering of the hexamers. The relevance of these results to density-functional
simulations of liquid water is also briefly discussed.


title:
On independent sets in purely atomic probability spaces with geometric
  distribution

abstract:
  We are interested in constructing concrete independent events in purely
atomic probability spaces with geometric distribution. Among other facts we
prove that there are uncountable many sequences of independent events.


title:
Perturbation of Nuclear Decay Rates During the Solar Flare of 13
  December 2006

abstract:
  Recently, Jenkins, et al. have reported the detection of correlations between
fluctuations in nuclear decay rates and Earth-Sun distance, which suggest that
nuclear decay rates can be affected by solar activity. In this paper, we report
the detection of a significant decrease in the decay of 54Mn during the solar
flare of 13 December 2006, whose x-rays were first recorded at 02:37 UT (21:37
EST on 12 December). Our detector was a 1 uCi sample of 54Mn, whose decay rate
exhibited a dip coincident in time with spikes in both the x-ray and proton
fluxes recorded by the GOES-10 and 11 satellites. A secondary peak in the x-ray
and proton fluxes on 17 December at 12:40 EST was also accompanied by a
coincident dip in the 54Mn decay rate. These observations support the claim by
Jenkins, et al. that nuclear decay rates vary with Earth-Sun distance.


title: Probing Supergravity Unified Theories at the Large Hadron Collider

abstract:
  The discovery of supersymmetry is one of the major goals of the current
experiments at the Tevatron and in proposed experiments at the Large Hadron
Collider (LHC). However when sparticles are produced the signatures of their
production will to a significant degree depend on their hierarchical mass
patterns. Here we investigate hierarchical mass patterns for the four lightest
sparticles within one of the leading candidate theories - the SUGRA model.
Specifically we analyze the hierarchies for the four lightest sparticles for
the mSUGRA as well as for a general class of supergravity unified models
including nonuniversalities in the soft breaking sector. It is shown that out
of nearly $10^4$ possibilities of sparticle mass hierarchies, only a small
number survives the rigorous constraints of radiative electroweak symmetry
breaking, relic density and other experimental constraints. The signature space
of these mass patterns at the LHC is investigated using a large set of final
states including multi-leptonic states, hadronically decaying $\tau$s, tagged
$b$ jets and other hadronic jets. In all, we analyze more than 40 such lepton
plus jet and missing energy signatures along with several kinematical
signatures such as missing transverse momentum, effective mass, and invariant
mass distributions of final state observables. It is shown that a composite
analysis can produce significant discrimination among sparticle mass patterns
allowing for a possible identification of the source of soft breaking. While
the analysis given is for supergravity models, the techniques used in the
analysis are applicable to wide class of models including string and brane
models.


title:
Towards a microscopic description of dimer adsorbates on metallic
  surfaces

abstract:
  Despite the experimental successes of Scanning Tunneling Microscopy (STM) and
the interest in more complex magnetic nanostructures, our present understanding
and theoretical description of STM spectra of magnetic adatoms is mainly
phenomenological and most often ignores many-body effects. Here, we propose a
theory which includes a microscopic description of the wave functions of the
substrate and magnetic adatoms together with quantum many-body effects. To test
our theory, we have computed the STM spectra of magnetic Cobalt monomers and
dimers adsorbed on metallic Copper surfaces and succesfully compared our
results to recent available experimental data.


title: Spin-isospin resonances: A self-consistent covariant description

abstract:
  For the first time a fully self-consistent charge-exchange relativistic RPA
based on the relativistic Hartree-Fock (RHF) approach is established. The
self-consistency is verified by the so-called isobaric analog state (IAS)
check. The excitation properties and the non-energy weighted sum rules of two
important charge-exchange excitation modes, the Gamow-Teller resonance (GTR)
and the spin-dipole resonance (SDR), are well reproduced in the doubly magic
nuclei $^{48}$Ca, $^{90}$Zr and $^{208}$Pb without readjustment of the
particle-hole residual interaction. The dominant contribution of the exchange
diagrams is demonstrated.


title: Critical heat flux around strongly-heated nanoparticles

abstract:
  We study heat transfer from a heated nanoparticle into surrounding fluid,
using molecular dynamics simulations. We show that the fluid next to the
nanoparticle can be heated well above its boiling point without a phase change.
Under increasing nanoparticle temperature, the heat flux saturates which is in
sharp contrast with the case of flat interfaces, where a critical heat flux is
observed followed by development of a vapor layer and heat flux drop. These
differences in heat transfer are explained by the curvature induced pressure
close to the nanoparticle, which inhibits boiling. When the nanoparticle
temperature is much larger than the critical fluid temperature, a very large
temperature gradient develops resulting in close to ambient temperature just
radius away from the particle surface


title: The W40 Cloud Complex

abstract:
  The W40 complex is a nearby site of recent massive star formation composed of
a dense molecular cloud adjacent to an HII region that contains an embedded OB
star cluster. The HII region is beginning to blister out and break free from
its envelope of molecular gas, but our line of sight to the central stars is
largely obscured by intervening dust. Several bright OB stars in W40 - visible
at optical, infrared, or cm wavelengths - are providing the ionizing flux that
heats the HII region. The known stellar component of W40 is dominated by a
small number of partly or fully embedded OB stars which have been studied at
various wavelengths, but the lower mass stellar population remains largely
unexamined. Despite its modest optical appearance, at 600pc W40 is one of the
nearest massive star forming regions, and with a UV flux of about 1/10th of the
Orion Nebula Cluster, this neglected region deserves detailed investigation.


title:
Noise-based logic: Binary, multi-valued, or fuzzy, with optional
  superposition of logic states

abstract:
  A new type of deterministic (non-probabilistic) computer logic system
inspired by the stochasticity of brain signals is shown. The distinct values
are represented by independent stochastic processes: independent voltage (or
current) noises. The orthogonality of these processes provides a natural way to
construct binary or multi-valued logic circuitry with arbitrary number N of
logic values by using analog circuitry. Moreover, the logic values on a single
wire can be made a (weighted) superposition of the N distinct logic values.
Fuzzy logic is also naturally represented by a two-component superposition
within the binary case (N=2). Error propagation and accumulation are
suppressed. Other relevant advantages are reduced energy dissipation and
leakage current problems, and robustness against circuit noise and background
noises such as 1/f, Johnson, shot and crosstalk noise. Variability problems are
also nonexistent because the logic value is an AC signal. A similar logic
system can be built with orthogonal sinusoidal signals (different frequency or
orthogonal phase) however that has an extra 1/N type slowdown compared to the
noise-based logic system with increasing number of N furthermore it is less
robust against time delay effects than the noise-based counterpart.


title: Bepcii and Besiii

abstract:
  The Beijing Electron Collider has been upgraded (BEPCII) to a two-ring
collider with a design luminosity of $1 \times 10^{33}$cm$^{-2}$ s$^{-1}$ at a
center-of-mass energy of 3.78 GeV. It will operate between 2 and 4.6 GeV in the
center of mass. With this luminosity, the BESIII detector will be able to
collect, for example, 10 billion $J/\psi$ events in one year of running. This
will be a unique facility in the world opening many physics opportunities.
BEPCII and BESIII are both currently being commissioned, first events have been
obtained, and data taking will take place in fall 2008.


title:
Searching for Narrow Emission Lines in X-ray Spectra: Computation and
  Methods

abstract:
  The detection and quantification of narrow emission lines in X-ray spectra is
a challenging statistical task. The Poisson nature of the photon counts leads
to local random fluctuations in the observed spectrum that often results in
excess emission in a narrow band of energy resembling a weak narrow line. From
a formal statistical perspective, this leads to a (sometimes highly) multimodal
likelihood. Many standard statistical procedures are based on (asymptotic)
Gaussian approximations to the likelihood and simply cannot be used in such
settings. Bayesian methods offer a more direct paradigm for accounting for such
complicated likelihood functions but even here multimodal likelihoods pose
significant computational challenges. The new Markov chain Monte Carlo (MCMC)
methods developed in 2008 by van Dyk and Park, however, are able to fully
explore the complex posterior distribution of the location of a narrow line,
and thus provide valid statistical inference. Even with these computational
tools, standard statistical quantities such as means and standard deviations
cannot adequately summarize inference and standard testing procedures cannot be
used to test for emission lines. In this paper, we use new efficient MCMC
algorithms to fit the location of narrow emission lines, we develop new
statistical strategies for summarizing highly multimodal distributions and
quantifying valid statistical inference, and we extend the method of posterior
predictive p-values proposed by Protassov et al. (2002) to test for the
presence of narrow emission lines in X-ray spectra. We illustrate and validate
our methods using simulation studies and apply them to the Chandra observations
of the high redshift quasar PG1634+706.


title:
Effects of interaction of electron donor and accepter molecules on the
  electronic structure of graphene

abstract:
  Effects of interaction of graphene with electron donor and acceptor molecules
have been investigated by employing Raman spectroscopy. The G band softens
progressively with the increasing concentration of tetrathiafulvalene (TTF)
which is an electron donor while the band stiffens with increasing
concentration of tetracyanoethylene (TCNE) which is an electron-acceptor
molecule. Both TTF and TCNE broaden the G-band. The 2D band position is also
affected by interaction with TTF and TCNE. The intensity of the 2D-band
decreases markedly with the concentration of either. The ratio of intensities
of the 2D and G bands decreases with increase in TTF and TCNE concentrations.
The electrical resistivity of graphene varies in opposite directions on
interaction with TTF and TCNE. All these effects occur due to molecular
charge-transfer, as evidenced by the observation of charge-transfer bands in
the electronic absorption spectra.


title: Privacy Preserving Association Rule Mining Revisited

abstract:
  The privacy preserving data mining (PPDM) has been one of the most
interesting, yet challenging, research issues. In the PPDM, we seek to
outsource our data for data mining tasks to a third party while maintaining its
privacy. In this paper, we revise one of the recent PPDM schemes (i.e., FS)
which is designed for privacy preserving association rule mining (PP-ARM). Our
analysis shows some limitations of the FS scheme in term of its storage
requirements guaranteeing a reasonable privacy standard and the high
computation as well. On the other hand, we introduce a robust definition of
privacy that considers the average case privacy and motivates the study of a
weakness in the structure of FS (i.e., fake transactions filtering). In order
to overcome this limit, we introduce a hybrid scheme that considers both
privacy and resources guidelines. Experimental results show the efficiency of
our proposed scheme over the previously introduced one and opens directions for
further development.


title:
Low energy theory of the t-t'-t''-U Hubbard Model at half-filling:
  interaction strengths in cuprate superconductors and an effective spin-only
  description of La_2CuO_4

abstract:
  Spin-only descriptions of the half-filled one-band Hubbard model are relevant
for a wide range of Mott insulators. In addition to the usual Heisenberg
exchange, many new types of interactions, including ring exchange, appear in
the effective Hamiltonian in the intermediate coupling regime. In order to
improve on the quantitative description of magnetic excitations in the
insulating antiferromagnetic phase of copper-oxide (cuprate) materials, and to
be consistent with band structure calculations and photoemission experiments on
these systems, we include second and third neighbor hopping parameters, t' and
t'', into the Hubbard Hamiltonian. A unitary transformation method is used to
find systematically the effective Hamiltonian and any operator in the spin-only
representation. The results include all closed, four hop electronic pathways in
the canonical transformation. The method generates many ring exchange terms
that play an important role in the comparison with experiments on La2CuO4.
Performing a spin wave analysis, we calculate the magnon dispersion as a
function of U,t,t' and t''. The four parameters are estimated by fitting the
magnon dispersion to the experimental results of Coldea et al. [Phys. Rev.
Lett. 86, 5377, {2001}] for La2CuO4. The ring exchange terms are found
essential, in particular to determine the relative sign of t' and t'', with the
values found in good agreement with independent theoretical and experimental
estimates for other members of the cuprate family. The zero temperature
sublattice magnetization is calculated using these parameters and also found to
be in good agreement with the experimental value estimated by Lee et al. [Phys.
Rev. B 60, 3643 (1999)]. We find a value of the interaction strength U~8t
consistent with Mott insulating behavior.


title: Width of exotics from QCD sum rules : tetraquarks or molecules?

abstract:
  We investigate the widths of the recently observed charmonium like resonances
X(3872), Z(4430) and Z_2(4250) using QCD sum rules. Extending previous analyses
regarding these states as diquark-antiquark states or molecules of D mesons, we
introduce the Breit-Wigner function in the pole term. We find that introducing
the width increases the mass at small Borel window region. Using the OPE up to
dimension eight, we find that the sum rules based on interpolating current with
molecular components give a stable Borel curve from which both the masses and
widths of these resonances can be well obtained. Thus the QCD sum rule approach
strongly favors the molecular description of these states.


title: Algebraic characterization of the isometries of the hyperbolic 5-space

abstract:
  Using the representation of the isometries as 2x2 invertible matrices over
the division algebra $\H$ of quaternions, we give an algebraic characterization
of the dynamical types of the orientation-preserving isometries of the
hyperbolic 5-space. We also determine the conjugacy classes and the conjugacy
classes of centralizers or the z-classes in $GL(2, \H)$.


title:
Extensivity of Irreversible Current and Stability in Causal Dissipative
  Hydrodynamics

abstract:
  We extended our formulation of causal dissipative hydrodynamics [T. Koide
\textit{et al.}, Phys. Rev. \textbf{C75}, 034909 (2007)] to be applicable to
the ultra-relativistic regime by considering the extensiveness of irreversible
currents. The new equation has a non-linear term which suppresses the effect of
viscosity. We found that such a term is necessary to guarantee the positive
definiteness of the inertia term and stabilize numerical calculations in
ultra-relativistic initial conditions. Because of the suppression of the
viscosity, the behavior of the fluid is more close to that of the ideal fluid.
Our result is essentially same as that from the extended irreversible
thermodynamics, but is different from the Israel-Stewart theory. A possible
origin of the difference is discussed.


title: Energy loss of charged particles in a two-dimensional Dirac plasma

abstract:
  The stopping power and energy loss rate of charged particles traversing a
two-dimensional Dirac plasma is investigated. The Dirac plasma considered here
models a solid state system, recently realized graphene monolayer, where the
conduction electrons obey the Dirac-like equation and exhibit a linear in
momentum dispersion relation. Theoretical work presented here is based on the
the dielectric response function and the dynamical structure function within
the Random-Phase-Approximation (RPA).


title: Reconstruction of the unitary symmetry in super-relativity

abstract:
  The reconstruction of the unitary symmetry \cite{TFD} under non-linear
dynamical mapping Hilbert space of action amplitudes $C^N$ onto projective
Hilbert space $CP(N-1)$ \cite{Le1} has been applied here to the quantum
dynamics of elementary vacuum excitations. The "vacuum manifold of virtual
action states" is represented here by $CP(N-1)$ whereas its tangent vectors
define local dynamical variables (LDV's) describing "matter". The conservation
laws of LDV's express self-conservation of the "material particles" during
continuous evolution being expressed as the affine parallel transport agrees
with Fubuni-Study metric, create the "affine gauge potential" as the solution
of the partial differential equations. Such procedure embeds the quantum
dynamics into dynamical space-time whose state-dependent coordinates arose due
to encoding results of quantum measurement by the qubit spinor whose components
subjected to Lorentz transformations of "quantum boosts" and "quantum
rotations". Thereby, in the framework of super-relativity, the objective
character of the quantum measurement is inherently related to the dynamical
space-time structure that replaces the notion of "observer".


title:
Probability distribution of (Schw\"{a}mmle and Tsallis) two-parameter
  entropies and the Lambert W-function

abstract:
  We investigate a two-parameter entropy introduced by Schw\"{a}mmle and
Tsallis and obtain its probability distribution in the canonical ensemble. The
probability distribution is given in terms of the Lambert W-function which has
been used in many branches of physics, especially in fractal structures. Also,
extensivity of $S_{q,q'}$ is discussed and a relationship is found to exist
between the probabilities of a composite system and its subsystems so that the
two-parameter entropy, $S_{q,q'}$, is extensive.


title: Infrared regularization with vector mesons and baryons

abstract:
  We extend the method of infrared regularization to spin-1 fields coupled to
baryons. As an application, we discuss the axial form factor of the nucleon.


title:
Conformal intercept of BFKL pomeron with NLO running coupling constant
  corrections

abstract:
  In the present note we propose a shift of the anomalous dimension function of
the eigenfunctions of the BFKL equation with the NLO running coupling
corrections. The calculated eigenvalue of the modified equation turns out to be
conformal invariant and we discuss consequences of this result.


title:
On the EPR-type Entanglement in the Experiments of Scully et Al. I. The
  Micromaser Case and Delayed-choice Quantum Erasure

abstract:
  Delayed-choice erasure is investigated in two-photon two-slit experiments
that are generalizations of the micromaser experiment of Scully et al. [Scully,
M. O. et al. Nature 351, 111-116 (1991)]. Applying quantum mechanics to the
localization detector, it is shown that erasure with delayed choice in the
sense of Scully, has an analogous structure as simple erasure. The description
goes beyond probabilities. The EPR-type disentanglement, consisting in two
mutually incompatible distant measurements, is used as a general framework in
both parts of this study. Two simple coherence cases are shown to emerge
naturally, and they are precisely the two experiments of Scully et al. The
treatment seems to require the relative-reality-of-unitarily-evolving-state
(RRUES) approach. Besides insight in the exoeriments, this study has also the
goal of insight in quantum mechanics. The question is if it can be more than
just a "book-keeping device" for calculating probabilities as Scully et al.
modestly and cautiously claim.


title:
On EPR-type Entanglement in the Experiments of Scully et Al. II. Insight
  in the Real Random Delayed-choice Erasure Experiment

abstract:
  It was pointed out in the first part of this study that EPR-type entanglement
is defined by the possibility of performing any of two mutually incompatible
distant, i. e.,direct-interaction-free, measurements. They go together under
the term 'EPR-type disentanglement'. In this second part, quantum-mechanical
insight is gained in the real random delayed-choice erasure experiment of Kim
et al. [Kim et al.: Phys. Rev. Lett. 84, 1-5 (2000)] by a relative-reality-of-
unitarily-evolving-state (RRUES) approach (explained in the first part).
Finally, it is shown that this remarkable experiment, which performs, by random
choice, two incompatible measurements at the same time, is actually an EPR-type
disentanglement experiment, closely related to the micromaser experiment
discussed in the first part.


title: Exact decoherence dynamics of a single-mode optical field

abstract:
  We apply the influence-functional method of Feynman and Vernon to the study
of a single-mode optical field that interacts with an environment at zero
temperature. Using the coherent-state formalism of the path integral, we derive
a generalized master equation for the single-mode optical field. Our analysis
explicitly shows how non-Markovian effects manifest in the exact decoherence
dynamics for different environmental correlation time scales. Remarkably, when
these are equal to or greater than the time scale for significant change in the
system, the interplay between the backaction-induced coherent oscillation and
the dissipative effect of the environment causes the non-Markovian effect to
have a significant impact not only on the short-time behavior but also on the
long-time steady-state behavior of the system.


title: Possible Detection of Causality Violation in a Non-local Scalar Model

abstract:
  We consider the possibility that there may be causality violation detectable
at higher energies. We take a scalar nonlocal theory containing a mass scale
$\Lambda$ as a model example and make a preliminary study of how the causality
violation can be observed. We show how to formulate an observable whose
detection would signal causality violation. We study the range of energies
(relative to $\Lambda$) and couplings to which the observable can be used.


title: On the uniqueness of weak solutions for the 3D Navier-Stokes equations

abstract:
  In this paper, we improve some known uniqueness results of weak solutions for
the 3D Navier-Stokes equations. The proof uses the Fourier localization
technique and the losing derivative estimates.


title:
Spontaneous Breaking of Lorentz-Invariance and Gravitons as Goldstone
  Particles

abstract:
  We consider some aspects of spontaneous breaking of Lorentz Invariance in
field theories, discussing the possibility that the certain tensor operators
may condensate in the ground state in which case the tensor Goldstone particles
would appear. We analyze their dynamics and discuss to which extent such a
theory could imitate the gravity. We are also interested if the universality of
coupling of such `gravitons' with other particles can be achieved in the
infrared limit. Then we address the more complicated models when such tensor
Goldstones coexist with the usual geometrical gravitons. At the end we examine
the properties of possible cosmological scenarios in the case of goldstone
gravity coexisting with geometrical gravity.


title: Dvali-Gabadadze-Porrati Cosmology in Bianchi I brane

abstract:
  The dynamics of Dvali-Gabadadze-Porrati Cosmology (DGP) braneworld with an
anisotropic brane is studied. The Friedmann equations and their solutions are
obtained for two branches of anisotropic DGP model. The late time behavior in
DGP cosmology is examined in the presence of anisotropy which shows that
universe enters a self-accelerating phase much later compared to the isotropic
case. The acceleration conditions and slow-roll conditions for inflation are
obtained.


title:
Semiconductor split-ring resonators for thermally tunable, terahertz
  metamaterials

abstract:
  As the variation of temperature alters the intrinsic carrier density in a
semiconductor, numerical simulations indicate that the consequent variation of
the relative permittivity in the terahertz regime provides a way to realize
thermally tunable split-ring resonators. Electromagnetic metasurfaces and
metamaterials that are thermally tunable in the terahertz regime can thus be
implemented.


title:
Thermal fluctuations and phase diagrams of the phase field crystal model
  with pinning

abstract:
  We study the influence of thermal fluctuations in the phase diagram of a
recently introduced two-dimensional phase field crystal model with an external
pinning potential. The model provides a continuum description of pinned lattice
systems allowing for both elastic deformations and topological defects. We
introduce a non-conserved version of the model and determine the ground-state
phase diagram as a function of lattice mismatch and strength of the pinning
potential. Monte Carlo simulations are used to determine the phase diagram as a
function of temperature near commensurate phases. The results show a rich phase
diagram with commensurate, incommensurate and liquid-like phases with a
topology strongly dependent on the type of ordered structure. A finite-size
scaling analysis of the melting transition for the $c(2 \times 2)$ commensurate
phase shows that the thermal correlation length exponent $\nu$ and specific
heat behavior are consistent with the Ising universality class as expected from
analytical arguments.


title:
Gamma-Ray Studies of Blazars: Synchro-Compton Analysis of Flat Spectrum
  Radio Quasars

abstract:
  We extend a method for modeling synchrotron and synchrotron self-Compton
radiations in blazar jets to include external Compton processes. The basic
model assumption is that the blazar radio through soft X-ray flux is nonthermal
synchrotron radiation emitted by isotropically-distributed electrons in the
randomly directed magnetic field of outflowing relativistic blazar jet plasma.
Thus the electron distribution is given by the synchrotron spectrum, depending
only on the Doppler factor $\delta_{\rm D}$ and mean magnetic field $B$, given
that the comoving emission region size scale $R_b^\prime \lesssim c \dD
t_v/(1+z)$, where $t_v$ is variability time and $z$ is source redshift.
Generalizing the approach of Georganopoulos, Kirk, and Mastichiadis (2001) to
arbitrary anisotropic target radiation fields, we use the electron spectrum
implied by the synchrotron component to derive accurate Compton-scattered
$\gamma$-ray spectra throughout the Thomson and Klein-Nishina regimes for
external Compton scattering processes. We derive and calculate accurate
$\gamma$-ray spectra produced by relativistic electrons that Compton-scatter
(i) a point source of radiation located radially behind the jet, (ii) photons
from a thermal Shakura-Sunyaev accretion disk and (iii) target photons from the
central source scattered by a spherically-symmetric shell of broad line region
(BLR) gas. Calculations of broadband spectral energy distributions from the
radio through $\gamma$-ray regimes are presented, which include self-consistent
$\gamma\gamma$ absorption on the same radiation fields that provide target
photons for Compton scattering. Application of this baseline flat spectrum
radio/$\gamma$-ray quasar model is considered in view of data from $\gamma$-ray
telescopes and contemporaneous multi-wavelength campaigns.


title: Tunneling with negative tension

abstract:
  We describe a new family of thin-wall instantons, with negative tension
bubble walls, that mediate tunneling between Minkowski or de Sitter vacua. Some
of these instantons can have exponentially enhanced tunneling rates, and would
dominate the Euclidean path integral, representing a severe non-perturbative
instability in any theory which supports them. We give two constructions of
these instantons in theories which are perturbatively stable, but violate the
null energy condition. One construction uses a scalar field theory with
higher-derivative kinetic term, and is similar to the Coleman-de Luccia
positive tension instanton. The other construction employs a negative-tension
boundary arising from Z_2 orbifolding: it resembles a "bubble of nothing" which
nucleates and grows, consuming the surrounding de Sitter or Minkowski
spacetime. We explain how the spectral flow for fluctutations about the
thin-wall tunneling solutions automatically protects causality, for both
positive and negative tension instantons. We comment briefly on the relation of
these solutions to a Kalzua-Klein "bubble of nothing," cosmological models
relying on ghost condensates, and string theory orientifolds.


title: The Annihilating-Ideal Graph of Commutative Rings I

abstract:
  Let $R$ be a commutative ring with ${\Bbb{A}}(R)$ its set of ideals with
nonzero annihilator. In this paper and its sequel, we introduce and investigate
the {\it annihilating-ideal graph} of $R$, denoted by ${\Bbb{AG}}(R)$. It is
the (undirected) graph with vertices
${\Bbb{A}}(R)^*:={\Bbb{A}}(R)\setminus\{(0)\}$, and two distinct vertices $I$
and $J$ are adjacent if and only if $IJ=(0)$. First, we study some finiteness
conditions of ${\Bbb{AG}}(R)$. For instance, it is shown that if $R$ is not a
domain, then ${\Bbb{AG}}(R)$ has ACC (resp., DCC) on vertices if and only if
$R$ is Noetherian (resp., Artinian). Moreover, the set of vertices of
${\Bbb{AG}}(R)$ and the set of nonzero proper ideals of $R$ have the same
cardinality when $R$ is either an Artinian or a decomposable ring. This yields
for a ring $R$, ${\Bbb{AG}}(R)$ has $n$ vertices $(n\geq 1)$ if and only if $R$
has only $n$ nonzero proper ideals. Next, we study the connectivity of
${\Bbb{AG}}(R)$. It is shown that ${\Bbb{AG}}(R)$ is a connected graph and
$diam(\Bbb{AG})(R)\leq 3$ and if ${\Bbb{AG}}(R)$ contains a cycle, then
$gr({\Bbb{AG}}(R))\leq 4$. Also, rings $R$ for which the graph ${\Bbb{AG}}(R)$
is complete or star, are characterized, as well as rings $R$ for which every
vertex of ${\Bbb{AG}}(R)$ is a prime (or maximal) ideal. In Part II we shall
study the diameter and coloring of annihilating-ideal graphs.


title: The Science of Galaxy Formation

abstract:
  Our knowledge of the Universe remains discovery-led: in the absence of
adequate physics-based theory, interpretation of new results requires a
scientific methodology. Commonly, scientific progress in astrophysics is
motivated by the empirical success of the "Copernican Principle", that the
simplest and most objective analysis of observation leads to progress. A
complementary approach tests the prediction of models against observation. In
practise, astrophysics has few real theories, and has little control over what
we can observe. Compromise is unavoidable. Advances in understanding complex
non-linear situations, such as galaxy formation, require that models attempt to
isolate key physical properties, rather than trying to reproduce complexity. A
specific example is discussed, where substantial progress in fundamental
physics could be made with an ambitious approach to modelling: simulating the
spectrum of perturbations on small scales.


title: The Annihilating-Ideal Graph of Commutative Rings II

abstract:
  In this paper we continue our study of annihilating-ideal graph of
commutative rings, that was introduced in Part I (see [5]). Let $R$ be a
commutative ring with ${\Bbb{A}}(R)$ its set of ideals with nonzero annihilator
and $Z(R)$ its set of zero divisors. The annihilating-ideal graph of $R$ is
defined as the (undirected) graph ${\Bbb{AG}}(R)$ that its vertices are
$\Bbb{A}(R)^* =\Bbb{A}(R)\hspace{-1mm}\setminus\{(0)\}$ in which for every
distinct vertices $I$ and $J$,
$I\hspace{-0.6mm}-\hspace{-1.7mm}-\hspace{-1.7mm}-\hspace{-0.5mm}J$ is an edge
if and only if $IJ=(0)$. First, we study the diameter of ${\Bbb{AG}}(R)$. A
complete characterization for the possible diameter is given exclusively in
terms of the ideals of $R$ when either $R$ is a Noetherian ring or $Z(R)$ is
not an ideal of $R$. Next, we study coloring of annihilating-ideal graphs.
Among other results, we characterize when either $\chi({\Bbb{AG}}(R))\leq 2$ or
$R$ is reduced and $\chi({\Bbb{AG}}(R))\leq \infty$. Also it is shown that for
each reduced ring $R$, $\chi(\Bbb{AG}(R))= cl(\Bbb{AG}(R))$. Moreover, if
  $\chi(\Bbb{AG}(R))$ is finite, then $R$ has a finite number of minimal
primes, and if $n$ is this number, then $\chi(\Bbb{AG}(R))= cl(\Bbb{AG}(R))=
n$. Finally, we show that for a Noetherian ring $R$, $cl(\Bbb{AG}(R))$ is
finite if and only if for every ideal $I$ of $R$ with $I^2=(0)$, $I$ has finite
number of $R$-submodules.


title:
An Extensive, Sensitive Search for SiO Masers in High- and
  Intermediate-Mass Star-Forming Regions

abstract:
  We present sensitive Very Large Array observations with an angular resolution
of a few arcseconds of the $J= 1 - 0$ line of SiO in the $v$=1 and 2
vibrationally excited states toward a sample of 60 Galactic regions in which
stars of high or intermediate mass are currently forming and/or have recently
formed. We report the detection of SiO maser emission in \textit{both}
vibrationally excited transitions toward only three very luminous regions:
Orion-KL, W51N and Sgr B2(M). Toward all three, SiO maser emission had
previously been reported, in Orion-KL in both lines, in W51N only in the $v=2$
line and in Sgr B2(M) only in the $v=1$ line. Our work confirms that SiO maser
emission in star-forming regions is a rare phenomenon, indeed, that requires
special, probably extreme, physical and chemical conditions not commonly found.
In addition to this SiO maser survey, we also present images of the
simultaneously observed 7 mm continuum emission from a subset of our sample of
star-forming regions where such emission was detected. This is in most cases
likely to be free-free emission from compact- and ultracompact-HII regions.


title:
Size dependent oscillator strength and quantum efficiency of CdSe
  quantum dots determined by controlling the local density of states

abstract:
  We study experimentally time-resolved emission of CdSe quantum dots in an
environment with a controlled local density of states (LDOS). The decay rate is
measured versus frequency and as a function of distance to a mirror. We observe
a linear relation between the decay rate and the LDOS, allowing us to determine
the size-dependent quantum efficiency and oscillator strength. We find that the
quantum efficiency decreases with increasing emission energy mostly due to an
increase in nonradiative decay. For the first time, we manage to obtain the
oscillator strength of the important class of CdSe quantum dots. The oscillator
strength varies weakly with frequency in agreement with behavior of quantum
dots in the strong confinement limit. Surprisingly, the measured absolute
values are a factor of 5 below theoretically calculated values. Our results are
relevant for applications of CdSe quantum dots in spontaneous emission control
and cavity quantum electrodynamics.


title: Entropy and chaos in the Kac model

abstract:
  We investigate the behavior in $N$ of the $N$--particle entropy functional
for Kac's stochastic model of Boltzmann dynamics, and its relation to the
entropy function for solutions of Kac's one dimensional nonlinear model
Boltzmann equation. We prove a number of results that bring together the notion
of propagation of chaos, which Kac introduced in the context of this model,
with the problem of estimating the rate of equilibration in the model in
entropic terms, and obtain a bound showing that the entropic rate of
convergence can be arbitrarily slow. Results proved here show that one can in
fact use entropy production bounds in Kac's stochastic model to obtain entropic
convergence bounds for his non linear model Boltzmann equation, though the
problem of obtaining optimal lower bounds of this sort for the original Kac
model remains open, and the upper bounds obtained here show that this problem
is somewhat subtle.


title:
Nonlinear theory of resonant slow waves in anisotropic and dispersive
  plasmas

abstract:
  The solar corona is a typical example of a plasma with strongly anisotropic
transport processes. The main dissipative mechanisms in the solar corona acting
on slow magnetoacoustic waves are the anisotropic thermal conductivity and
viscosity. Ballai et al. [Phys. Plasmas 5, 252 (1998)] developed the nonlinear
theory of driven slow resonant waves in such a regime. In the present paper the
nonlinear behaviour of driven magnetohydrodynamic waves in the slow dissipative
layer in plasmas with strongly anisotropic viscosity and thermal conductivity
is expanded by considering dispersive effects due to Hall currents. The
nonlinear governing equation describing the dynamics of nonlinear resonant slow
waves is supplemented by a term which describes nonlinear dispersion and is of
the same order of magnitude as nonlinearity and dissipation. The connection
formulae are found to be similar to their non-dispersive counterparts.


title:
Nonparametric goodness-of fit testing in quantum homodyne tomography
  with noisy data

abstract:
  In the framework of quantum optics, we study the problem of goodness-of-fit
testing in a severely ill-posed inverse problem. A novel testing procedure is
introduced and its rates of convergence are investigated under various
smoothness assumptions. The procedure is derived from a projection-type
estimator, where the projection is done in $\mathbb{L}_2$ distance on some
suitably chosen pattern functions. The proposed methodology is illustrated with
simulated data sets.


title:
Oblique Ion Two-Stream Instability in the Foot Region of a Collisionless
  Shock

abstract:
  Electrostatic behavior of a collisionless plasma in the foot region of high
Mach number perpendicular shocks is investigated through the two-dimensional
linear analysis and electrostatic particle-in-cell (PIC) simulation. The
simulations are double periodic and taken as a proxy for the situation in the
foot. The linear analysis for relatively cold unmagnetized plasmas with a
reflected proton beam shows that obliquely propagating Buneman instability is
strongly excited. We also found that when the electron temperature is much
higher than the proton temperature, the most unstable mode is the highly
obliquely propagating ion two-stream instability excited through the resonance
between ion plasma oscillations of the background protons and of the beam
protons, rather than the ion acoustic instability that is dominant for parallel
propagation. To investigate nonlinear behavior of the ion two-stream
instability, we have made PIC simulations for the shock foot region in which
the initial state satisfies the Buneman instability condition. In the first
phase, electrostatic waves grow two-dimensionally by the Buneman instability to
heat electrons. In the second phase, highly oblique ion two-stream instability
grows to heat mainly ions. This result is in contrast to previous studies based
on one-dimensional simulations, for which ion acoustic instability further
heats electrons. The present result implies that overheating problem of
electrons for shocks in supernova remnants is resolved by considering ion
two-stream instability propagating highly obliquely to the shock normal and
that multi-dimensional analysis is crucial to understand the particle heating
and acceleration processes in shocks.


title: Queue-length Variations In A Two-Restaurant Problem

abstract:
  This paper attempts to find out numerically the distribution of the
queue-length ratio in the context of a model of preferential attachment. Here
we consider two restaurants only and a large number of customers (agents) who
come to these restaurants. Each day the same number of agents sequentially
arrives and decides which restaurant to enter. If all the agents literally
follow the crowd then there is no difference between this model and the famous
`P\'olya's Urn' model. But as agents alter their strategies different kind of
dynamics of the model is seen. It is seen from numerical results that the
existence of a distribution of the fixed points is quite robust and it is also
seen that in some cases the variations in the ratio of the queue-lengths follow
a power-law.


title: On the Monotonicity of Work Function in k-Server Conjecture

abstract:
  This paper presents a mistake in work function algorithm of k-server
conjecture. That is, the monotonicity of the work function is not always true.


title: Electron Beam Supercollimation in Graphene Superlattices

abstract:
  Although electrons and photons are intrinsically different, importing useful
concepts in optics to electronics performing similar functions has been
actively pursued over the last two decades. In particular, collimation of an
electron beam is a long-standing goal. We show that ballistic propagation of an
electron beam with virtual no spatial spreading or diffraction, without a
waveguide or external magnetic field, can be achieved in graphene under an
appropriate class of experimentally feasible one-dimensional external periodic
potentials. The novel chiral quasi-one-dimensional metallic state that the
charge carriers are in originates from a collapse of the intrinsic helical
nature of the charge carriers in graphene owing to the superlattice potential.
Beyond providing a new way to constructing chiral one-dimensional states in two
dimensions, our findings should be useful in graphene-based electronic devices
(e.g., for information processing) utilizing some of the highly developed
concepts in optics.


title:
Gas Sensing Properties of Single Conducting Polymer Nanowires and the
  Effect of Temperature

abstract:
  We measured the electronic properties and gas sensing responses of
template-grown poly(3,4-ethylenedioxythiophene)/poly(styrenesulfonate)
(PEDOT/PSS)-based nanowires. The nanowires have a "striped" structure
(gold-PEDOT/PSS-gold), typically 8um long (1um-6um-1um for each section,
respectively) and 220 nm in diameter. Single-nanowire devices were contacted by
pre-fabricated gold electrodes using dielectrophoretic assembly. A polymer
conductivity of 11.5 +/- 0.7 S/cm and a contact resistance of 27.6 +/- 4 kOhm
were inferred from measurements of nanowires of varying length and diameter.
The nanowire sensors detect a variety of odors, with rapid response and
recovery (seconds). The response (R-R0)/R0 varies as a power law with analyte
concentration.


title: Multifactor Analysis of Multiscaling in Volatility Return Intervals

abstract:
  We study the volatility time series of 1137 most traded stocks in the US
stock markets for the two-year period 2001-02 and analyze their return
intervals $\tau$, which are time intervals between volatilities above a given
threshold $q$. We explore the probability density function of $\tau$,
$P_q(\tau)$, assuming a stretched exponential function, $P_q(\tau) \sim
e^{-\tau^\gamma}$. We find that the exponent $\gamma$ depends on the threshold
in the range between $q=1$ and 6 standard deviations of the volatility. This
finding supports the multiscaling nature of the return interval distribution.
To better understand the multiscaling origin, we study how $\gamma$ depends on
four essential factors, capitalization, risk, number of trades and return. We
show that $\gamma$ depends on the capitalization, risk and return but almost
does not depend on the number of trades. This suggests that $\gamma$ relates to
the portfolio selection but not on the market activity. To further characterize
the multiscaling of individual stocks, we fit the moments of $\tau$, $\mu_m
\equiv <(\tau/<\tau>)^m>^{1/m}$, in the range of $10 < <\tau> \le 100$ by a
power-law, $\mu_m \sim <\tau>^\delta$. The exponent $\delta$ is found also to
depend on the capitalization, risk and return but not on the number of trades,
and its tendency is opposite to that of $\gamma$. Moreover, we show that
$\delta$ decreases with $\gamma$ approximately by a linear relation. The return
intervals demonstrate the temporal structure of volatilities and our findings
suggest that their multiscaling features may be helpful for portfolio
optimization.


title:
High Angular Resolution Observations at 7-mm of the Core of the
  Quadrupolar HH 111/121 Outflow

abstract:
  We present sensitive, high angular resolution ($0\rlap.{''}05$) VLA continuum
observations made at 7 mm of the core of the HH 111/121 quadrupolar outflow. We
estimate that at this wavelength the continuum emission is dominated by dust,
although a significant free-free contribution ($\sim$30%) is still present. The
observed structure is formed by two overlapping, elongated sources
approximately perpendicular to each other as viewed from Earth. We interpret
this structure as either tracing two circumstellar disks that exist around each
of the protostars of the close binary source at the core of this quadrupolar
outflow or a disk and a jet perpendicular to it. Both interpretations have
advantages and disadvantages, and future high angular resolution spectroscopic
millimeter observations are required to favor one of them in a more conclusive
way.


title: Uniqueness of pairings in Hopf-cyclic cohomology

abstract:
  We show that all pairings defined in the literature extending
Connes-Moscovici characteristic map in Hopf-cyclic cohomology are isomorphic as
natural transformations of derived double functors.


title: Sex is always well worth its two-fold cost

abstract:
  Sex is considered as an evolutionary paradox, since its evolutionary
advantage does not necessarily overcome the two fold cost of sharing half of
one's offspring's genome with another member of the population. Here we
demonstrate that sexual reproduction can be evolutionary stable even when its
Darwinian fitness is twice as low when compared to the fitness of asexual
mutants. We also show that more than two sexes are always evolutionary
unstable. Our approach generalizes the evolutionary game theory to analyze
species whose members are able to sense the sexual state of their conspecifics
and to switch sexes consequently. The widespread emergence and maintenance of
sex follows therefore from its co-evolution with even more widespread
environmental sensing abilities.


title: Symplectic polynomial invariants of one or two matrices of small size

abstract:
  The algebra of holomorphic polynomial Sp_{2n}-invariants of k complex 2n by
2n matrices (under diagonal conjugation action) is generated by the traces of
words in these matrices and their symplectic adjoints. No concrete minimal
generating set is known for this algebra apart from the cases n=1, when
Sp_2=SL_2, and n=2, k=1. We construct such sets in the cases n=k=2 and n=3,
k=1. In the latter case we also construct a homogeneous system of parameters
and a Hironaka decomposition of the algebra.


title:
Compression and stretching of a self-avoiding chain in cylindrical
  nanopores

abstract:
  Force-induced deformations of a self-avoiding chain confined inside a
cylindrical cavity, with diameter $D$, are probed using molecular dynamics
simulations, scaling analysis, and analytical calculations. We obtain and
confirm a simple scaling relation $-f \cdot D \sim R^{-9/4}$ in the
strong-compression regime, while for weak deformations we find $f \cdot D =
-A(R/R_0) + B (R/R_0)^{-2}$, where $A$ and $B$ are constants, $f$ the external
force, and $R$ the chain extension (with $R_0$ its unperturbed value). For a
strong stretch, we present a universal, analytical force-extension relation.
Our results can be used to analyze the behavior of biomolecules in confinement.


title: The Stadium Theorem

abstract: A proof of a curious planar embedding theorem.


title: Chamaeleon

abstract:
  The dark clouds in the constellation of Chamaeleon have distances of 160-180
pc from the Sun and a total mass of ~5000 M_sun. The three main clouds, Cha I,
II, and III, have angular sizes of a few square degrees and maximum extinctions
of A_V=5-10. Most of the star formation in these clouds is occurring in Cha I,
with the remainder in Cha II. The current census of Cha I contains 237 known
members, 33 of which have spectral types indicative of brown dwarfs (>M6).
Approximately 50 members of Cha II have been identified, including a few brown
dwarfs. When interpreted with the evolutionary models of Chabrier and Baraffe,
the H-R diagram for Cha I exhibits a median age of ~2 Myr, making it coeval
with IC 348 and slightly older than Taurus (~1 Myr). The IMF of Cha I reaches a
maximum at a mass of 0.1-0.15 M_sun, and thus closely resembles the IMFs in IC
348 and the Orion Nebula Cluster. The disk fraction in Cha I is roughly
constant at ~50% from 0.01 to 0.3 M_sun and increases to ~65% at higher masses.
In comparison, IC 348 has a similar disk fraction at low masses but a much
lower disk fraction at M>1 M_sun, indicating that solar-type stars have longer
disk lifetimes in Cha I.


title: Maximizing orbits for higher dimensional convex billiards

abstract:
  The main result of this paper is, that for convex billiards in higher
dimensions, in contrast with 2D case, for every point on the boundary and for
every $n$ there always exist billiard trajectories developing conjugate points
at the $n$-th collision with the boundary. We shall explain that this is a
consequence of the following variational property of the billiard orbits in
higher dimension. If a segment of an orbit is locally maximizing, then it can
not pass too close to the boundary. This fact follows from the second variation
formula for the Length functional. It turns out that this formula behaves
differently with respect to "longitudinal" and "transversal" variations.


title: Baric structures on triangulated categories and coherent sheaves

abstract:
  We introduce the notion of a "baric structure" on a triangulated category, as
an abstraction of S. Morel's weight truncation formalism for mixed l-adic
sheaves. We study these structures on the derived category D_G(X) of
G-equivariant coherent sheaves on a G-scheme X. Our main result shows how to
endow this derived category with a family of nontrivial baric structures when G
acts on X with finitely many orbits.
  We also describe a general construction for producing a new t-structure on a
triangulated category equipped with given t- and baric structures, and we prove
that the staggered t-structures on D_G(X) introduced by the first author arise
in this way.


title: Purity and decomposition theorems for staggered sheaves

abstract:
  Two major results in the theory of l-adic mixed constructible sheaves are the
purity theorem (every simple perverse sheaf is pure) and the decomposition
theorem (every pure object in the derived category is a direct sum of shifts of
simple perverse sheaves). In this paper, we prove analogues of these results
for coherent sheaves. Specificially, we work with staggered sheaves, which form
the heart of a certain t-structure on the derived category of equivariant
coherent sheaves. We prove, under some reasonable hypotheses, that every simple
staggered sheaf is pure, and that every pure complex of coherent sheaves is a
direct sum of shifts of simple staggered sheaves.


title: Quantum transport thermometry for electrons in graphene

abstract:
  We propose a method of measuring the electron temperature $T_e$ in mesoscopic
conductors and demonstrate experimentally its applicability to micron-size
graphene devices in the linear-response regime ($T_e\approx T$, the bath
temperature). The method can be {especially useful} in case of overheating,
$T_e>T$. It is based on analysis of the correlation function of mesoscopic
conductance fluctuations. Although the fluctuation amplitude strongly depends
on the details of electron scattering in graphene, we show that $T_e$ extracted
from the correlation function is insensitive to these details.


title: Quantum Control via Geometry: An explicit example

abstract:
  We explicitly compute the optimal cost for a class of example problems in
geometric quantum control. These problems are defined by a Cartan decomposition
of $su(2^n)$ into orthogonal subspaces $\mathfrak{l}$ and $\mathfrak{p}$ such
that $[\mathfrak{l},\mathfrak{l}] \subseteq \mathfrak{p},
[\mathfrak{p},\mathfrak{l}] = \mathfrak{p}, [\mathfrak{p},\mathfrak{p}]
\subseteq \mathfrak{l}$. Motion in the $\mathfrak{l}$ direction are assumed to
have negligible cost, where motion in the $\mathfrak{p}$ direction do not. In
the special case of two qubits, our results correspond to the minimal
interaction cost of a given unitary.


title: High M/L ratios of UCDs: a variation of the IMF?

abstract:
  Various studies have established that the dynamical M/L ratios of
ultra-compact dwarf galaxies (UCDs) tend to be at the limit or beyond the range
explicable by standard stellar populations with canonical IMF. We discuss how
IMF variations may account for these high M/L ratios and how observational
approaches may in the future allow to discriminate between those possibilities.
We also briefly discuss the possibility of dark matter in UCDs.


title: The discrete Fourier transform: A canonical basis of eigenfunctions

abstract:
  The discrete Fourier transform (DFT) is an important operator which acts on
the Hilbert space of complex valued functions on the ring Z/NZ. In the case
where N=p is an odd prime number, we exhibit a canonical basis of eigenvectors
for the DFT. The transition matrix from the standard basis to the canonical
basis defines a novel transform which we call the "discrete oscillator
transform" (DOT for short). Finally, we describe a fast algorithm for computing
the DOT in certain cases.


title:
Quantitative Description of Strong-Coupling of Quantum Dots in
  Microcavities

abstract:
  We have recently developed a self-consistent theory of Strong-Coupling in the
presence of an incoherent pumping [arXiv:0807.3194] and shown how it could
reproduce quantitatively the experimental data [PRL 101, 083601 (2008)]. Here,
we summarize our main results, provide the detailed analysis of the fitting of
the experiment and discuss how the field should now evolve beyond merely
qualitative expectations, that could well be erroneous even when they seem to
be firmly established.


title:
Defects in Four-Dimensional Continua: A Paradigm for the Expansion of
  the Universe?

abstract:
  The presence of defects in material continua is known to produce internal
permanent strained states. Extending the theory of defects to four dimensions
and allowing for the appropriate signature, it is possible to apply these
concepts to space-time. In this case a defect would induce a non-trivial metric
tensor, which can be interpreted as a gravitational field. The image of a
defect in space-time can be applied to the description of the Big Bang. A
review of the four-dimensional generalisation of defects and an application to
the expansion of the universe will be presented.


title:
Driven particle in a random landscape: disorder correlator, avalanche
  distribution and extreme value statistics of records

abstract:
  We review how the renormalized force correlator Delta(u), the function
computed in the functional RG field theory, can be measured directly in
numerics and experiments on the dynamics of elastic manifolds in presence of
pinning disorder. We show how this function can be computed analytically for a
particle dragged through a 1-dimensional random-force landscape. The limit of
small velocity allows to access the critical behavior at the depinning
transition. For uncorrelated forces one finds three universality classes,
corresponding to the three extreme value statistics, Gumbel, Weibull, and
Frechet. For each class we obtain analytically the universal function Delta(u),
the corrections to the critical force, and the joint probability distribution
of avalanche sizes s and waiting times w. We find P(s)=P(w) for all three
cases. All results are checked numerically. For a Brownian force landscape,
known as the ABBM model, avalanche distributions and Delta(u) can be computed
for any velocity. For 2-dimensional disorder, we perform large-scale numerical
simulations to calculate the renormalized force correlator tensor
Delta_{ij}(u), and to extract the anisotropic scaling exponents zeta_x >
zeta_y. We also show how the Middleton theorem is violated. Our results are
relevant for the record statistics of random sequences with linear trends, as
encountered e.g. in some models of global warming. We give the joint
distribution of the time s between two successive records and their difference
in value w.


title: Balanced HKT metrics and strong HKT metrics on hypercomplex manifolds

abstract:
  A manifold (M,I,J,K) is called hypercomplex if I,J,K are complex structures
satisfying quaternionic relations. A quaternionic Hermitian metric is called
HKT (hyperkaehler with torsion) if $Id\omega_I = Jd \omega_J=Kd\omega_K$, where
$\omega_I,\omega_J, \omega_K$ are Hermitian forms associated with I, J, K. A
Hermitian metric $\omega$ on a complex manifold is called balanced if
$d^*\omega=0$. We show that balanced HKT metrics are precisely the quaternionic
Calabi-Yau metrics defined in terms of the quaternionic Monge-Ampere equation.
In particular, a balanced HKT-metric is unique in its cohomology class, and it
always exists if the quaternionic Calabi-Yau theorem is true. We investigate
the cohomological properties of strong HKT metrics (the quaternionic Hermitian
metrics, satisfying, in addition to the HKT condition, the relation $dd^c
\omega=0$), and show that the space of strong HKT metrics is
finite-dimensional. Using Howe's duality for representations of Sp(n), we prove
a hyperkaehler version of Hodge-Riemann bilinear relations. We use it to show
that a manifold admitting a balanced HKT-metric never admits a strong
HKT-metric, if $\dim_\R M \geq 12$.


title: Zakharov-Shabat system and hyperbolic pseudoanalytic function theory

abstract:
  In [1] a hyperbolic analogue of pseudoanalytic function theory was developed.
In the present contribution we show that one of the central objects of the
inverse problem method the Zakharov-Shabat system is closely related to a
hyperbolic Vekua equation for which among other results a generating sequence
and hence a complete system of formal powers can be constructed explicitly.


title: Open book decompositions and stable Hamiltonian structures

abstract:
  We show that every open book decomposition of a contact 3-manifold can be
represented (up to isotopy) by a smooth R-invariant family of pseudoholomorphic
curves on its symplectization with respect to a suitable stable Hamiltonian
structure. In the planar case, this family survives small perturbations, and
thus gives a concrete construction of a stable finite energy foliation that has
been used in various applications to planar contact manifolds, including the
Weinstein conjecture and equivalence of strong and Stein fillability.


title:
Can optical afterglows be used to discriminate between Type I and Type
  II GRBs?

abstract:
  The precise localization of short/hard (Type I) gamma-ray bursts (GRBs) in
recent years has answered many questions but raised even more. I present some
results of a systematic study of the optical afterglows of long/soft (Type II)
and short/hard (Type I) GRBs, focusing on the optical luminosity as another
puzzle piece in the classification of GRBs.


title: Analysis of the postulates produced by Karp's Theorem

abstract:
  This is the final article in a series of four articles. Richard Karp has
proven that a deterministic polynomial time solution to K-SAT will result in a
deterministic polynomial time solution to all NP-Complete problems. However, it
is demonstrated that a deterministic polynomial time solution to any
NP-Complete problem does not necessarily produce a deterministic polynomial
time solution to all NP-Complete problems.


title: Isoscaling and the high Temperature limit

abstract:
  This study shows that isoscaling, usually studied in nuclear reactions, is a
phenomenon common to all cases of fair sampling. Exact expressions for the
yield ratio $R_{21}$ and approximate expressions for the isoscaling parameters
$\alpha$ and $\beta$ are obtained and compared to experimental results. It is
concluded that nuclear isoscaling is bound to contain a component due to
sampling and, thus, a words of caution is issued to those interested in
extracting information about the nuclear equation of state from isoscaling.


title: The Kuiper Belt and Other Debris Disks

abstract:
  We discuss the current knowledge of the Solar system, focusing on bodies in
the outer regions, on the information they provide concerning Solar system
formation, and on the possible relationships that may exist between our system
and the debris disks of other stars. Beyond the domains of the Terrestrial and
giant planets, the comets in the Kuiper belt and the Oort cloud preserve some
of our most pristine materials. The Kuiper belt, in particular, is a
collisional dust source and a scientific bridge to the dusty "debris disks"
observed around many nearby main-sequence stars. Study of the Solar system
provides a level of detail that we cannot discern in the distant disks while
observations of the disks may help to set the Solar system in proper context.


title: Entire curves, Integral sets and Principal bundles

abstract:
  We compare the behaviour of entire curves and integral sets, in particular in
relation to locally trivial fiber bundles, algebraic groups and finite ramified
covers over semi-abelian varieties.


title: A Molecular Line Survey of the Highly Evolved Carbon Star CIT 6

abstract:
  We present a spectral line survey of the C-rich envelope CIT 6 in the 2mm and
1.3mm bands carried out with the Arizona Radio Observatory (ARO) 12m telescope
and the Heinrich Hertz Submillimeter Telescope (SMT). The observations cover
the frequency ranges of 131--160 GHz, 219--244 GHz, and 252--268 GHz with
typical sensitivity limit of T_R<10 mK. A total of 74 individual emission
features are detected, of which 69 are identified to arise from 21 molecular
species and isotopologues, with 5 faint lines remaining unidentified. Two new
molecules (C4H and CH3CN) and seven new isotopologues (C17O, 29SiC2, 29SiO,
30SiO, 13CS, C33S, and CS) are detected in this object for the first time. The
column densities, excitation temperatures, and fractional abundances of the
detected molecules are determined using rotation diagram analysis. Comparison
of the spectra of CIT 6 to that of IRC+10216 suggests that the spectral
properties of CIT 6 are generally consistent with those of IRC+10216. For most
of the molecular species, the intensity ratios of the lines detected in the two
objects are in good agreement with each other. Nevertheless, there is evidence
suggesting enhanced emission from CN and HC3N and depleted emission from HCN,
SiS, and C4H in CIT 6. Based on their far-IR spectra, we find that CIT 6
probably has a lower dust-to-molecular gas ratio than IRC+10216. To investigate
the chemical evolution of evolved stars, we compare the molecular abundances in
the AGB envelopes CIT 6 and IRC+10216 and those in the bright proto-planetary
nebula CRL 618. The implication on the circumstellar chemistry is discussed.


title:
Observations of Active Region Loops with the EUV Imaging Spectrometer on
  Hinode

abstract:
  Previous solar observations have shown that coronal loops near 1 MK are
difficult to reconcile with simple heating models. These loops have lifetimes
that are long relative to a radiative cooling time, suggesting quasi-steady
heating. The electron densities in these loops, however, are too high to be
consistent with thermodynamic equilibrium. Models proposed to explain these
properties generally rely on the existence of smaller scale filaments within
the loop that are in various stages of heating and cooling. Such a framework
implies that there should be a distribution of temperatures within a coronal
loop. In this paper we analyze new observations from the EUV Imaging
Spectrometer (EIS) on \textit{Hinode}. EIS is capable of observing active
regions over a wide range of temperatures (\ion{Fe}{8}--\ion{Fe}{17}) at
relatively high spatial resolution (1\arcsec). We find that most isolated
coronal loops that are bright in \ion{Fe}{12} generally have very narrow
temperature distributions ($\sigma_T \lesssim 3\times10^5$ K), but are not
isothermal. We also derive volumetric filling factors in these loops of
approximately 10%. Both results lend support to the filament models.


title: Hydro-Gravitational-Dynamics of Planets and Dark Energy

abstract:
  Self-gravitational fluid mechanical methods termed
hydro-gravitational-dynamics (HGD) predict plasma fragmentation 0.03 Myr after
the turbulent big bang to form protosuperclustervoids, turbulent
protosuperclusters, and protogalaxies at the 0.3 Myr transition from plasma to
gas. Linear protogalaxyclusters fragment at 0.003 Mpc viscous-inertial scales
along turbulent vortex lines or in spirals, as observed. The plasma
protogalaxies fragment on transition into white-hot planet-mass gas clouds
(PFPs) in million-solar-mass clumps (PGCs) that become globular-star-clusters
(GCs) from tidal forces or dark matter (PGCs) by freezing and diffusion into
0.3 Mpc halos with 97% of the galaxy mass. The weakly collisional non-baryonic
dark matter diffuses to > Mpc scales and frag-ments to form galaxy cluster
halos. Stars and larger planets form by binary mergers of the trillion PFPs per
PGC on 0.03 Mpc galaxy accretion disks. Star deaths depend on rates of planet
accretion and internal star mixing. Moderate accretion rates produce white
dwarfs that evaporate surrounding gas planets by spin-radiation to form
planetary nebulae before Supernova Ia events, dimming some events to give
systematic distance errors misinterpreted as the dark energy hypothesis and
overestimates of the universe age. Failures of standard LCDM cosmological
models reflect not only obsolete Jeans 1902 fluid mechanical assumptions, but
also failures of standard turbulence models that claim the cascade of turbulent
kinetic energy is from large scales to small. Because turbulence is always
driven at all scales by inertial-vortex forces the turbulence cascade is always
from small scales to large.


title: Hopping Transport in Hostile Reaction-Diffusion Systems

abstract:
  We investigate transport in a disordered reaction-diffusion (RD) model
consisting of particles which are allowed to diffuse, compete with one another
(2A->A), give birth in small areas called "oases" (A->2A), and die in the
"desert" outside the oases (A->0). This model has previously been used to study
bacterial populations in the lab and is related to a model of plankton
populations in the oceans. We first consider the nature of transport between
two oases: in the limit of high growth rate, this is effectively a first
passage process, and we are able to determine the first passage time
probability density function in the limit of large oasis separation. This
result is then used along with the theory of hopping conduction in doped
semiconductors to estimate the time taken by a population to cross a large
system.


title:
Phase Transitions on Fixed Connected Graphs and Random Graphs in the
  Presence of Noise

abstract:
  In this paper, we study the phase transition behavior emerging from the
interactions among multiple agents in the presence of noise. We propose a
simple discrete-time model in which a group of non-mobile agents form either a
fixed connected graph or a random graph process, and each agent, taking bipolar
value either +1 or -1, updates its value according to its previous value and
the noisy measurements of the values of the agents connected to it. We present
proofs for the occurrence of the following phase transition behavior: At a
noise level higher than some threshold, the system generates symmetric behavior
(vapor or melt of magnetization) or disagreement; whereas at a noise level
lower than the threshold, the system exhibits spontaneous symmetry breaking
(solid or magnetization) or consensus. The threshold is found analytically. The
phase transition occurs for any dimension. Finally, we demonstrate the phase
transition behavior and all analytic results using simulations. This result may
be found useful in the study of the collective behavior of complex systems
under communication constraints.


title: Multi-Instance Multi-Label Learning

abstract:
  In this paper, we propose the MIML (Multi-Instance Multi-Label learning)
framework where an example is described by multiple instances and associated
with multiple class labels. Compared to traditional learning frameworks, the
MIML framework is more convenient and natural for representing complicated
objects which have multiple semantic meanings. To learn from MIML examples, we
propose the MimlBoost and MimlSvm algorithms based on a simple degeneration
strategy, and experiments show that solving problems involving complicated
objects with multiple semantic meanings in the MIML framework can lead to good
performance. Considering that the degeneration process may lose information, we
propose the D-MimlSvm algorithm which tackles MIML problems directly in a
regularization framework. Moreover, we show that even when we do not have
access to the real objects and thus cannot capture more information from real
objects by using the MIML representation, MIML is still useful. We propose the
InsDif and SubCod algorithms. InsDif works by transforming single-instances
into the MIML representation for learning, while SubCod works by transforming
single-label examples into the MIML representation for learning. Experiments
show that in some tasks they are able to achieve better performance than
learning the single-instances or single-label examples directly.


title: Towards Gravity solutions of AdS/CMT

abstract:
  In this short note, we have generalized and constructed gravity solutions
with two "exponents" {\it a la} Kachru, Liu and Mulligan. The coordinate system
that is used to construct the gravity solution is useful when $b$ vanishes. It
means we can describe the theory having only the temporal scale invariance
apart from the combination of both temporal and spatial scale invariance. The
two point correlation function of the scalar field in the mass less limit is
computed in a special case that is $a/b=2$.


title: Topological censorship for Kaluza-Klein space-times

abstract:
  The standard topological censorship theorems require asymptotic hypotheses
which are too restrictive for several situations of interest. In this paper we
prove a version of topological censorship under significantly weaker
conditions, compatible e.g. with solutions with Kaluza-Klein asymptotic
behavior. In particular we prove simple connectedness of the quotient of the
domain of outer communications by the group of symmetries for models which are
asymptotically flat, or asymptotically anti-de Sitter, in a Kaluza-Klein sense.
This allows one, e.g., to define the twist potentials needed for the reduction
of the field equations in uniqueness theorems. Finally, the methods used to
prove the above are used to show that weakly trapped compact surfaces cannot be
seen from Scri.


title: Theory for Superconductivity in Iron Pnictides at Large Coulomb U Limit

abstract:
  Superconductivity in iron pnictides is studied by using a two-orbital Hubbard
model in the large U limit. The Coulomb repulsion induces an orbital-dependent
pairing between charge carriers. The pairing is found mainly from the
scattering within the same Fermi pocket. The inter-pocket pair scatterings
determine the symmetry of the superconductivity, which is extended s-wave at
small Hund's coupling, and d-wave at large Hund's coupling and large U. The
former is consistent with recent experiments of ARPES and Andreev reflection
spectroscope.


title: Chen--Ruan cohomology of some moduli spaces

abstract:
  Let X be a compact connected Riemann surface of genus at least two. We
compute the Chen--Ruan cohomology ring of the moduli space of stable PSL(2,
C)--bundles of nontrivial second Stiefel--Whitney class over X.


title:
Coset Space Dimensional Reduction and Wilson Flux Breaking of
  Ten-Dimensional N=1, E(8) Gauge Theory

abstract:
  We consider a N=1 supersymmetric E(8) gauge theory, defined in ten dimensions
and we determine all four-dimensional gauge theories resulting from the
generalized dimensional reduction a la Forgacs-Manton over coset spaces,
followed by a subsequent application of the Wilson flux spontaneous symmetry
breaking mechanism. Our investigation is constrained only by the requirements
that (i) the dimensional reduction leads to the potentially phenomenologically
interesting, anomaly free, four-dimensional E(6), SO(10) and SU(5) GUTs and
(ii) the Wilson flux mechanism makes use only of the freely acting discrete
symmetries of all possible six-dimensional coset spaces.


title:
The role of Dirac equations in the classical mechanics of the
  relativistic top

abstract:
  A rigorous \textit{ab initio} derivation of the (square of) Dirac's equation
for a single particle with spin is presented. The general Hamilton-Jacobi
equation for the particle expressed in terms of a background Weyl's conformal
geometry is found to be linearized, exactly and in closed form, by an
\textit{ansatz} solution that can be straightforwardly interpreted as the
"quantum wave function" $\psi_4$ of the 4-spinor Dirac's equation. In
particular, all quantum features of the model arise from a subtle interplay
between the conformal curvature of the configuration space acting as a
potential and Weyl's "pre-potential" closely related to $\psi_4$, which acts on
the particle trajectory. The theory, carried out here by assuming a Minkowsky
metric, can be easily extended to arbitrary space-time Riemann metric, e.g. the
one adopted in the context of General Relativity. This novel theoretical
scenario, referred to as "Affine Quantum Mechanics", appears to be of general
application and is expected to open a promising perspective in the modern
endeavor aimed at the unification of the natural forces with gravitation.


title:
Concentration of 1-Lipschitz maps into an infinite dimensional
  $\ell^p$-ball with $\ell^q$-distance function

abstract:
  In this paper, we study the L\'{e}vy-Milman concentration phenomenon of
1-Lipschitz maps into infinite dimensional metric spaces. Our main theorem
asserts that the concentration to an infinite dimensional $\ell^p$-ball with
the $\ell^q$-distance function for $1\leq p<q\leq +\infty$ is equivalent to the
concentration to the real line.


title:
Stability of Circular Orbits in General Relativity: A Phase Space
  Analysis

abstract:
  Phase space method provides a novel way for deducing qualitative features of
nonlinear differential equations without actually solving them. The method is
applied here for analyzing stability of circular orbits of test particles in
various physically interesting environments. The approach is shown to work in a
revealing way in Schwarzschild spacetime. All relevant conclusions about
circular orbits in the Schwarzschild-de Sitter spacetime are shown to be
remarkably encoded in a single parameter. The analysis in the rotating Kerr
black hole readily exposes information as to how stability depends on the ratio
of source rotation to particle angular momentum. As a wider application, it is
exemplified how the analysis reveals useful information when applied to motion
in a refractive medium, for instance, that of optical black holes.


title:
New Features of Extended Wormhole Solutions in the Scalar Field Gravity
  Theories

abstract:
  The present paper reports interesting new features that wormhole solutions in
the scalar field gravity theory have. To demonstrate these, we obtain, by using
a slightly modified form of the Matos-Nunez algorithm, an extended class of
asymptotically flat wormhole solutions belonging to Einstein minimally coupled
scalar field theory. Generally, solutions in these theories do not represent
traversable wormholes due to the occurrence of curvature singularities.
However, the Ellis I solution of the Einstein minimally coupled theory, when
Wick rotated, yields Ellis class III solution, the latter representing a
singularity-free traversable wormhole. We see that Ellis I and III are not
essentially independent solutions. The Wick rotated seed solutions, extended by
the algorithm, contain two new parameters a and \delta;. The effect of the
parameter a on the geodesic motion of test particles reveals some remarkable
features. By arguing for Sagnac effect in the extended Wick rotated solution,
we find that the parameter a can indeed be interpreted as a rotation parameter
of the wormhole. The analyses reported here have wider applicability in that
they can very well be adopted in other theories, including in the string
theory.


title: Moduli of Continuity of Quasiregular Mappings

abstract:
  This thesis consists of Chapters 1 and 2. The main results are contained in
the two preprints and two published papers, listed below. Chapter 1 deals with
conformal invariants in the euclidean space Rn; n >= 2; and their
interrelation. In particular, conformally invariant metrics and balls of the
respective metric spaces are studied. Another theme in Chapter 1 is the study
of quasiconformal maps with identity boundary values in two diferent cases, the
unit ball and the whole space minus two points. These results are based on the
two preprints: R. Klen, V. Manojlovic and M. Vuorinen: Distortion of two point
normalized quasiconformal mappings, arXiv:0808.1219[math.CV], 13 pp., V.
Manojlovic and M. Vuorinen: On quasiconformal maps with identity boundary
values, arXiv:0807.4418[math.CV], 16 pp. Chapter 2 deals with harmonic
quasiregular maps. Topics studied are: Preservation of modulus of continuity,
in particular Lipschitz continuity, from the boundary to the interior of domain
in case of harmonic quasiregular maps and quasiisometry property of harmonic
quasiconformal maps. Chapter 2 is based mainly on the two published papers: M.
Arsenovic, V. Kojic and M. Mateljevic: On Lipschitz continuity of harmonic
quasiregular maps on the unit ball in Rn., Ann. Acad. Sci. Fenn. Math. 33
(2008), no. 1, 315-318. V. Kojic and M. Pavlovic: Subharmonicity of jfjp for
quasiregular harmonic functions, with applications, J. Math. Anal. Appl. 342
(2008) 742-746


title: N=8 superfield formulation of the Bagger-Lambert-Gustavsson model

abstract:
  We reformulate the Bagger-Lambert-Gustavsson model using an N=8 superspace,
thus making the full supersymmetry manifest. The formulation is based on
appropriate "pure spinor wave functions" for the Chern-Simons and matter
multiplets. The Lagrangian has an extremely simple structure, essentially
containing a Chern-Simons-like term for the gauge field wave function and a
minimally coupled matter wave function. No higher order interactions than cubic
are present. The consistency of the setup relies on an interplay between the
algebraic structures of the 3-algebra and of the pure spinors.


title: How complex is the quantum motion?

abstract:
  In classical mechanics the complexity of a dynamical system is characterized
by the rate of local exponential instability which effaces the memory of
initial conditions and leads to practical irreversibility. In striking
contrast, quantum mechanics appears to exhibit strong memory of the initial
state. Here we introduce a notion of complexity for a quantum system and relate
it to its stability and reversibility properties.


title: Duality between quasi-concave functions and monotone linkage functions

abstract:
  A function $F$ defined on all subsets of a finite ground set $E$ is
quasi-concave if $F(X\cup Y)\geq\min\{F(X),F(Y)\}$ for all $X,Y\subset E$.
Quasi-concave functions arise in many fields of mathematics and computer
science such as social choice, theory of graph, data mining, clustering and
other fields.
  The maximization of quasi-concave function takes, in general, exponential
time. However, if a quasi-concave function is defined by associated monotone
linkage function then it can be optimized by the greedy type algorithm in a
polynomial time.
  Quasi-concave functions defined as minimum values of monotone linkage
functions were considered on antimatroids, where the correspondence between
quasi-concave and bottleneck functions was shown (Kempner & Levit, 2003). The
goal of this paper is to analyze quasi-concave functions on different families
of sets and to investigate their relationships with monotone linkage functions.


title: Initial correlations in nonequilibrium Falicov-Kimball model

abstract:
  The Keldysh boundary problem in a nonequilibrium Falicov-Kimball model in
infinite dimensions is studied within the truncated and self-consistent
perturbation theories, and the dynamical mean-field theory. Within the model
the system is started in equilibrium, and later a uniform electric field is
turned on. The Kadanoff-Baym-Wagner equations for the nonequilibrium Green
functions are derived, and numerically solved. The contributions of initial
correlations are studied by monitoring the system evolution. It is found that
the initial correlations are essential for establishing full electron
correlations of the system and independent on the starting time of preparing
the system in equilibrium. By examining the contributions of the initial
correlations to the electric current and the double occupation, we find that
the contributions are small in relation to the total value of those physical
quantities when the interaction is weak, and significantly increase when the
interaction is strong. The neglect of initial correlations may cause artifacts
in the nonequilibrium properties of the system, especially in the strong
interaction case.


title:
Stability and decay-rates for the five-dimensional Schwarzschild metric
  under biaxial perturbations

abstract:
  In this paper we prove the non-linear asymptotic stability of the
five-dimensional Schwarzschild metric under biaxial vacuum perturbations. This
is the statement that the evolution of (SU(2) x U(1))-symmetric vacuum
perturbations of initial data for the five-dimensional Schwarzschild metric
finally converges in a suitable sense to a member of the Schwarzschild family.
It constitutes the first result proving the existence of non-stationary vacuum
black holes arising from asymptotically flat initial data dynamically
approaching a stationary solution. In fact, we show quantitative rates of
approach. The proof relies on vectorfield multiplier estimates, which are used
in conjunction with a bootstrap argument to establish polynomial decay rates
for the radiation on the perturbed spacetime. Despite being applied here in a
five-dimensional context, the techniques are quite robust and may admit
applications to various four-dimensional stability problems.


title:
Maximal Inequalities in Bilateral Grand Lebesque Spaces Over Unbounded
  Measure

abstract:
  In this paper non-asymptotic exact rearrangement invariant norm estimates are
derived for the maximum distribution of the family elements of some
rearrangement invariant (r.i.) space over unbounded measure in the entropy
terms and in the terms of generic chaining.
  We consider some applications in the martingale theory and in the theory of
Fourier series.


title: Support of Borelian Measures in Separable Banach Spaces

abstract:
  We prove in this article that every Borelian measure, for example, the
distribution of a random variable, in separable Banach space has a support
which is compact embedded Banach subspace; and prove that if the norm of the
random variable belongs to some exponential Orlicz space, then the new subspace
can be choose such that the norm of this variable in the new space also belongs
to other exponential Orlicz space.


title:
Differentiability of Lipschitz maps from metric measure spaces to Banach
  spaces with the Radon Nikodym property

abstract:
  We prove the differentiability of Lipschitz maps X-->V, where X is a complete
metric measure space satisfying a doubling condition and a Poincar\'e
inequality, and V is a Banach space with the Radon Nikodym Property (RNP). The
proof depends on a new characterization of the differentiable structure on such
metric measure spaces, in terms of directional derivatives in the direction of
tangent vectors to suitable rectifiable curves.


title:
Effective Hamiltonian of Three-orbital Hubbard Model on Pyrochlore
  Lattice: Application to LiV_2O_4

abstract:
  We investigate heavy fermion behaviors in the vanadium spinel LiV_2O_4. We
start from a three-orbital Hubbard model on the pyrochlore lattice and derive
its low-energy effective Hamiltonian by an approach of real-space
renormalization group type. One important tetrahedron configuration in the
rochlore lattice has a three-fold orbital degeneracy and spin S=1, and
correspondingly, the effective Hamiltonian has spin and orbital exchange
interactions of Kugel-Khomskii type as well as correlated electron hoppings.
Analyzing the effective Hamiltonian, we find that ferromagnetic double exchange
processes compete with antiferromagnetic superexchange processes and various
spin and orbital exchange processes are competing to each other. These results
suggest the absence of phase transition in spin and orbital spaces down to very
low temperatures and their large fluctuations in the low-energy sector, which
are key issues for understanding the heavy fermion behavior in LiV_2O_4.


title:
Observation of Quantum Capacitance of individual single walled carbon
  nanotubes

abstract:
  We report a measurement on quantum capacitance of individual semiconducting
and small band gap SWNTs. The observed quantum capacitance is remarkably
smaller than that originating from density of states and it implies a strong
electron correlation in SWNTs.


title:
Asymptotical behavior of one class of $p$-adic singular Fourier
  integrals

abstract:
  We study the asymptotical behavior of the $p$-adic singular Fourier integrals
$$ J_{\pi_{\alpha},m;\phi}(t) =\bigl< f_{\pi_{\alpha};m}(x)\chi_p(xt),
\phi(x)\bigr> =F\big[f_{\pi_{\alpha};m}\phi\big](t), \quad |t|_p \to \infty,
\quad t\in \bQ_p, $$ where $f_{\pi_{\alpha};m}\in {\cD}'(\bQ_p)$ is a {\em
quasi associated homogeneous} distribution (generalized function) of degree
$\pi_{\alpha}(x)=|x|_p^{\alpha-1}\pi_1(x)$ and order $m$, $\pi_{\alpha}(x)$,
$\pi_1(x)$, and $\chi_p(x)$ are a multiplicative, a normed multiplicative, and
an additive characters of the field $\bQ_p$ of $p$-adic numbers, respectively,
$\phi \in {\cD}(\bQ_p)$ is a test function, $m=0,1,2...$, $\alpha\in \bC$. If
$Re\alpha>0$ the constructed asymptotics constitute a $p$-adic version of the
well known Erd\'elyi lemma. Theorems which give asymptotic expansions of
singular Fourier integrals are the Abelian type theorems. In contrast to the
real case, all constructed asymptotics have the {\it stabilization} property.


title: Champs alg\'ebriques et foncteur de Picard

abstract:
  This text is my thesis, defended in June 2007, in the status it was at this
time. The most important results are contained in the article "Foncteur de
Picard d'un champ alg\'ebrique" to appear in "Mathematische Annalen" (see the
preprint arXiv:0711.4545). In the article, some results have been added, and
some previous results have been strengthened. However, the proofs of the
results contained in the appendix (concerning the smooth-\'etale cohomology on
an algebraic stack) have been removed. The thesis is only put on the ArXiv to
provide a more lasting reference than my webpage for these proofs.


title:
Effect of Co doping on superconductivity and transport properties in
  SmFe$_{1-x}$Co$_{x}$AsO

abstract:
  We investigate superconductivity and transport properties of Co doped
SmFe$_{1-x}$Co$_{x}$AsO system. The antiferromagnetic (AFM) spin-density wave
(SDW) order is rapidly suppressed by Co doping, and superconductivity emerges
as $x$ $\geq$ 0.05. $T_c$$^{mid}$ increases with increasing Co content, shows a
maximum of 17.2 K at the optimally doping of $x\sim$ 0.10. A phase diagram is
derived based on the transport measurements and a dome-like $T_c$ versus $x$
curve is established. Meanwhile we found that the normal state thermopower
might consist of two different contributions. One contribution increases
gradually with increasing $x$, and the other contribution is abnormally
enhanced in the superconducting window 0.05 $\leq$ $x$ $\leq$ 0.20, and shows a
dome-like doping dependence. A close correlation between $T_{c}$ and the
abnormally enhanced term of thermopower is proposed.


title:
Impact of Uncertainties in the Cosmological Parameters on the
  Measurement of Primordial non-Gaussianity

abstract:
  We study the impact of cosmological parameters' uncertainties on estimates of
the primordial NG parameter f_NL in local and equilateral models of
non-Gaussianity. We show that propagating these errors increases the f_NL
relative uncertainty by 16% for WMAP and 5 % for Planck in the local case,
whereas for equilateral configurations the correction term are 14% and 4%,
respectively. If we assume for local f_NL a central value of order 60,
according to recent WMAP 5-years estimates, we obtain for Planck a final
correction \Delta f_NL = 3. Although not dramatic, this correction is at the
level of the expected estimator uncertainty for Planck, and should then be
taken into account when quoting the significance of an eventual future
detection. In current estimates of f_NL the cosmological parameters are held
fixed at their best-fit values. We finally note that the impact of
uncertainties in the cosmological parameters on the final f_NL error bar would
become totally negligible if the parameters were allowed to vary in the
analysis and then marginalized over.


title: Heat Transport in low-dimensional systems

abstract:
  Recent results on theoretical studies of heat conduction in low-dimensional
systems are presented. These studies are on simple, yet nontrivial, models.
Most of these are classical systems, but some quantum-mechanical work is also
reported. Much of the work has been on lattice models corresponding to phononic
systems, and some on hard particle and hard disc systems. A recently developed
approach, using generalized Langevin equations and phonon Green's functions, is
explained and several applications to harmonic systems are given. For
interacting systems, various analytic approaches based on the Green-Kubo
formula are described, and their predictions are compared with the latest
results from simulation. These results indicate that for momentum-conserving
systems, transport is anomalous in one and two dimensions, and the thermal
conductivity kappa, diverges with system size L, as kappa ~ L^alpha. For one
dimensional interacting systems there is strong numerical evidence for a
universal exponent alpha =1/3, but there is no exact proof for this so far. A
brief discussion of some of the experiments on heat conduction in nanowires and
nanotubes is also given.


title: Role of the N*(1440) resonance in the pp->pnpi+ reaction

abstract:
  New measurement by CELSIUS-WASA Collaboration on the pp->pn pi+ reaction
reveals clear evidence for the presence of the Roper resonance N*(1440) which
has been ignored in previous theoretical calculations. In this article, based
on an effective Lagrangian approach and available knowledge on the Roper
resonance, we investigate the role of the Roper resonance for the pp->pn pi+
reaction. It is found that the contribution from the Roper resonance N*(1440)
becomes significant for kinetic energy above 1.1 GeV, consistent with the new
experimental observation. The t-channel sigma-meson exchange is dominant for
the production of the Roper resonance.


title:
Ratliff-Rush Filtration, regularity and depth of Higher Associated
  graded modules: Part II

abstract:
  Let $(A,\m)$ be a Noetherian local ring, let $M$ be a finitely generated \CM
  $A$-module of dimension $r \geq 2$ and let $I$ be an ideal of definition for
$M$. Set $L^I(M) = \bigoplus_{n\geq 0}M/I^{n+1}M$. In part one of this paper we
showed that $L^I(M)$ is a module over $\R$, the Rees algebra of $I$ and we gave
many applications of $L^I(M)$ to study the associated graded module,
  $G_I(M)$. In this paper we give many further applications of our technique;
most notable is a reformulation of a classical result due to Narita in terms of
the Ratliff-Rush filtration. This reformulation can be extended to all
dimensions $\geq 2$.