title: Towards optimal DRP scheme for linear advection

abstract:
  Finite difference schemes are here solved by means of a linear matrix
equation. The theoretical study of the related algebraic system is exposed, and
enables us to minimize the error due to a finite difference approximation,
while building a new DRP scheme in the same time.


title:
Anisotropic behaviour law for sheets used in stamping: A comparative
  study of steel and aluminium

abstract:
  For a car manufacturer, reducing the weight of vehicles is an obvious aim.
Replacing steel by aluminium moves towards that goal. Unfortunately,
aluminium's stamping numerical simulation results are not yet as reliable as
those of steel. Punch-strength and spring-back phenomena are not correctly
described. This study on aluminium validates the behaviour law Hill 48
quadratic yield criterion with both isotropic and kinematic hardening. It is
based on the yield surface and on associated experimental tests (uniaxial test,
plane tensile test, plane compression and tensile shearing).


title:
The influence of crack-imbalance orientation and orbital evolution for
  an extended cracked Jeffcott rotor

abstract:
  Vibration peaks occurring at rational fractions of the fundamental rotating
critical speed, here named Local Resonances, facilitate cracked shaft detection
during machine shut-down. A modified Jeffcott-rotor on journal bearings
accounting for gravity effects and oscillating around nontrivial equilibrium
points is employed. Modal parameter selection allows this linear model to
represent first mode characteristics of real machines. Orbit evolution and
vibration patterns are analyzed, yielding useful results. Crack detection
results indicate that, instead of 1x and 2x components, analysis of the
remaining local resonances should have priority; this is due to crack-residual
imbalance interaction and to 2x multiple induced origins. Therefore, local
resonances and orbital evolution around 1/2, 1/3 and 1/4 of the critical speed
are emphasized for various crack-imbalance orientations.


title:
The invariant manifold approach applied to nonlinear dynamics of a
  rotor-bearing system

abstract:
  The invariant manifold approach is used to explore the dynamics of a
nonlinear rotor, by determining the nonlinear normal modes, constructing a
reduced order model and evaluating its performance in the case of response to
an initial condition. The procedure to determine the approximation of the
invariant manifolds is discussed and a strategy to retain the speed dependent
effects on the manifolds without solving the eigenvalue problem for each spin
speed is presented. The performance of the reduced system is analysed in
function of the spin speed.


title:
The maximum number of singular points on rational homology projective
  planes

abstract:
  A normal projective complex surface is called a rational homology projective
plane if it has the same Betti numbers with the complex projective plane
$\mathbb{C}\mathbb{P}^2$. It is known that a rational homology projective plane
with quotient singularities has at most 5 singular points. So far all known
examples have at most 4 singular points. In this paper, we prove that a
rational homology projective plane $S$ with quotient singularities such that
$K_S$ is nef has at most 4 singular points except one case. The exceptional
case comes from Enriques surfaces with a configuration of 9 smooth rational
curves whose Dynkin diagram is of type $ 3A_1 \oplus 2A_3$.
  We also obtain a similar result in the differentiable case and in the
symplectic case under certain assumptions which all hold in the algebraic case.


title: Involutions in $S_n$ and associated coadjoint orbits

abstract:
  In the paper we study the coadjoint orbits of the group $\mathrm{UT}(n,K)$
associated with involutions. We obtain a formula for dimension of the orbit. We
construct a polarization for the canonical element of orbit. We find a system
of generators in the defining ideal of orbit.


title: Poisson bracket in classical field theory as a derived bracket

abstract:
  We construct a Leibniz bracket on the space $\Omega^\bullet (J^k (\pi))$ of
all differential forms over the finite-dimensional jet bundle $J^k (\pi)$. As
an example, we write Maxwell equations with sources in the covariant
finite-dimensional hamiltonian form.


title: Construction of Z4-linear Reed-Muller codes

abstract:
  New quaternary Plotkin constructions are given and are used to obtain new
families of quaternary codes. The parameters of the obtained codes, such as the
length, the dimension and the minimum distance are studied. Using these
constructions new families of quaternary Reed-Muller codes are built with the
peculiarity that after using the Gray map the obtained Z4-linear codes have the
same parameters and fundamental properties as the codes in the usual binary
linear Reed-Muller family. To make more evident the duality relationships in
the constructed families the concept of Kronecker inner product is introduced.


title: On index of certain nilpotent Lie algebras

abstract:
  We introduce the method of calculation of index of Lie algebras that are
factors of the unitriangular Lie algebra with respect to ideals spanned by
subsets of root vectors.


title:
Transmission Eigenvalue Densities and Moments in Chaotic Cavities from
  Random Matrix Theory

abstract:
  We point out that the transmission eigenvalue density and higher order
correlation functions in chaotic cavities for an arbitrary number of incoming
and outgoing leads $(N_1,N_2)$ are analytically known from the Jacobi ensemble
of Random Matrix Theory. Using this result and a simple linear statistic, we
give an exact and non-perturbative expression for moments of the form
$<\lambda_1^m>$ for $m>-|N_1-N_2|-1$ and $\beta=2$, thus improving the existing
results in the literature. Secondly, we offer an independent derivation of the
average density and higher order correlation functions for $\beta=2,4$ which
does not make use of the orthogonal polynomials technique. This result may be
relevant for an efficient numerical implementation avoiding determinants.


title: Estimation of quadratic variation for two-parameter diffusions

abstract:
  In this paper we give a central limit theorem for the weighted quadratic
variations process of a two-parameter Brownian motion. As an application, we
show that the discretized quadratic variations $\sum_{i=1}^{[n s]}
\sum_{j=1}^{[n t]} | \Delta_{i,j} Y |^2$ of a two-parameter diffusion
$Y=(Y_{(s,t)})_{(s,t)\in[0,1]^2}$ observed on a regular grid $G_n$ is an
asymptotically normal estimator of the quadratic variation of $Y$ as $n$ goes
to infinity.


title: Astroparticle Physics: Puzzles and Discoveries

abstract:
  Puzzles often give birth to the great discoveries, the false discoveries
sometimes stimulate the exiting ideas in theoretical physics. The historical
examples of both are described in Introduction and in section ``Cosmological
Puzzles''. From existing puzzles most attention is given to Ultra High Energy
Cosmic Ray (UHECR) puzzle and to cosmological constant problem. The 40-years
old UHECR problem consisted in absence of the sharp steepening in spectrum of
extragalactic cosmic rays caused by interaction with CMB radiation. This
steepening is known as Greisen-Zatsepin-Kuzmin (GZK) cutoff. It is demonstrated
here that the features of interaction of cosmic ray protons with CMB are seen
now in the spectrum in the form of the dip and beginning of the GZK cutoff. The
most serious cosmological problem is caused by large vacuum energy of the known
elementary-particle fields which exceeds at least by 45 orders of magnitude the
cosmological vacuum energy. The various ideas put forward to solve this problem
during last 40 years, have weaknesses and cannot be accepted as the final
solution of this puzzle. The anthropic approach is discussed.


title:
Cosmological Constraints for the Cold Dark Matter and Model Building
  based on the Flavor Symmetric Radiative Seesaw Model

abstract:
  It is now clear that the masses of the neutrino sector are much lighter than
those of the other three sectors.There are many attempts to explain the
neutrino masses radiatively by means of inert Higgses, which don't have vacuum
expectation values. Then one can discuss cold dark matter candidates, because
of no needing so heavy particles and having a $Z_2$ parity symmetry
corresponding to the R-parity symmetry of the MSSM.
  The most famous work would be the Zee model.
  Recently a new type model along this line of thought was proposed by Mr. E.
Ma. We paid attention to this idea. We introduce a flavor symmetry based on a
dihedral group $D_6$ to constrain the Yukawa sector. For the neutrino sector,
we find that the maximal mixing of atmospheric neutrinos is realized, it can
also be shown that only an inverted mass spectrum, the value of
$|V_{MNS_{13}}|$ is 0.0034 and so on. When one extends the Higgs sector, it
leads to FCNCs mediated by Higgs fields generally. But in our model, the FCNCs
are (of course) suppressed for the experiments sufficiently. For the fermionic
CDM candidates, we find that the mass of the CDM and the inert Higgs should be
larger than about 230 and 300 GeV, respectively. If we restrict ourselves to a
perturbative regime, they should be lighter than about 750 GeV.


title:
Formation of Global Tendencies : Scientific Hypothesis About Destruction
  of Civilizations

abstract:
  The new explanation of global tendencies (in particular, of natural
calamities and other disasters, taking place in present time in different
countries) is suggested.


title:
Electron-vibration interaction in single-molecule junctions: from
  contact to tunneling regime

abstract:
  Point contact spectroscopy on a H2O molecule bridging Pt electrodes reveals a
clear crossover between enhancement and reduction of the conductance due to
electron-vibration interaction. As single channel models predict such a
crossover at transmission probability of t=0.5, we used shot noise measurements
to analyze the transmission and observed at least two channels across the
junction where the dominant channel has t=0.51+/-0.01 transmission probability
at the crossover conductance, which is consistent with the predictions for
single-channel models.


title:
Quantization of the Relativistic Fluid in Physical Phase Space on
  K\"{a}hler Manifolds

abstract:
  We discuss the quantization of a class of relativistic fluid models defined
in terms of one real and two complex conjugate potentials with values on a
K\"{a}hler manifold, and parametrized by the K\"{a}hler potential
$K(z,\bar{z})$ and a real number $\lambda$. In the hamiltonian formulation, the
canonical conjugate momenta of the potentials are subjected to second class
constraints which allow us to apply the symplectic projector method in order to
find the physical degrees of freedom and the physical hamiltonian. We construct
the quantum theory for that class of models by employing the canonical
quantization methods. We also show that a semiclassical theory in which the
K\"{a}hler and the complex potential are not quantized has a highly degenerate
vacuum. Also, we define and compute the quantum topological number (quantum
linking number) operator which has non-vanishing contributions from the
K\"{a}hler and complex potentials only. Finally, we show that the vacuum and
the states formed by tensoring the number operators eigenstates have zero
linking number and show that linear combinations of the tensored number
operators eigenstates which have the form of entangled states have non-zero
linking number.


title:
Non-linear dynamic of rotor-stator system with non-linear bearing
  clearance

abstract:
  The study deals with a rotor-stator contact inducing vibration in rotating
machinery. A numerical rotor-stator system, including a non-linear bearing with
Hertz contact and clearance is considered. To determine the non-linear
responses of this system, non-linear dynamic equations can be integrated
numerically. However, this procedure is both time consuming and costly to
perform. The aim of this Note is to apply the Alternate Frequency/Time Method
and the 'path following continuation' in order to obtain the non-linear
responses to this problem. Then the orbits of rotor and stator responses at
various speeds are investigated.


title: The influence of cracks in rotating shafts

abstract:
  In this paper, the influence of transverse cracks in a rotating shaft is
analysed. The paper addresses the two distinct issues of the changes in modal
properties and the influence of crack breathing on dynamic response during
operation. Moreover, the evolution of the orbit of a cracked rotor near half of
the first resonance frequency is investigated. The results provide a possible
basis for an on-line monitoring system. In order to conduct this study, the
dynamic response of a rotor with a breathing crack is evaluated by using the
alternate frequency/time domain approach. It is shown that this method
evaluates the nonlinear behaviour of the rotor system rapidly and efficiently
by modelling the breathing crack with a truncated Fourier series. The dynamic
response obtained by applying this method is compared with that evaluated
through numerical integration. The resulting orbit during transient operation
is presented and some distinguishing features of a cracked rotor are examined.


title:
ELT instrumentation for seeing-limited and AO-corrected observations: A
  comparison

abstract:
  The next generation of large ground-based optical and infrared telescopes
will provide new challenges for designers of astronomical instrumentation. The
varied science cases for these extremely large telescopes (ELTs) require a
large range of angular resolutions, from near diffraction-limited performance
via correction of atmospheric turbulence using adaptive optics (AO), to
seeing-limited observations. Moreover, the scientific output of the telescopes
must also be optimized with the consideration that, with current technology, AO
is relatively ineffective at visible wavelengths, and that atmospheric
conditions will often preclude high-performance AO. This paper explores some of
the issues that arise when designing ELT instrumentation that operates across a
range of angular resolutions and wavelengths. We show that instruments designed
for seeing-limited or seeing-enhanced observations have particular challenges
in terms of size and mass, while diffraction-limited instruments are not as
straightforward as might be imagined.


title: Smart Focal Plane Technologies for VLT Instruments

abstract:
  As we move towards the era of ELTs, it is timely to think about the future
role of the 8-m class telescopes. Under the OPTICON programme, novel
technologies have been developed that are intended for use in multi-object and
integral-field spectrographs. To date, these have been targeted at instrument
concepts for the European ELT, but there are also significant possibilities for
their inclusion in new VLT instruments, ensuring the continued success and
productivity of these unique telescopes.


title: Tunka-133 EAS Cherenkov Array: Status of 2007

abstract:
  The new EAS Cherenkov array Tunka-133, with about 1 km**2 sensitive area, is
being installed in the Tunka Valley since the end of 2005. This array will
permit a detailed study of the cosmic ray energy spectrum and the mass
composition in the energy range of 10**15-10**18 eV with a unique method. The
array will consist of 19 clusters, each composed of 7 optical detectors. The
first cluster started operation in October 2006. We describe the data
acquisition system and present preliminary results from data taken with the
first cluster.


title: Heat kernels on Euclidean complexes

abstract:
  In this thesis we describe a type of metric space called an Euclidean
polyhedral complex. We define a Dirichlet form on it; this is used to give a
corresponding heat kernel. We provide a uniform small time Poincare inequality
for complexes with bounded geometry and use this to determine uniform small
time heat kernel bounds via a theorem of Sturm. We then consider such complexes
with an underlying finitely generated group structure. We use techniques of
Saloff-Coste and Pittet to show a large time asymptotic equivalence for the
heat kernel on the complex and the heat kernel on the group.


title: Flavour Physics: Now and in the LHC era

abstract:
  We present an overview of what we learned so far from low-energy flavour
observables, concerning physics beyond the Standard Model, and what we could
still learn from further studies in flavour physics in the next few years.


title: Twisted stable maps to tame Artin stacks

abstract:
  This paper is a continuation of our earlier development of a theory of tame
Artin stacks. Our main goal here is the construction of an appropriate analogue
of Kontsevich's space of stable maps in the case where the target is a tame
Artin stack. When the target is a tame Deligne--Mumford stack, the theory was
developed by Abramovich and Vistoli, and found a number of applications. The
theory for arbitrary tame Artin stacks developed here is very similar, but it
is necessary to overcome a number of technical hurdles and to generalize a few
questions of foundation.


title: Interpolation by entire functions with growth conditions

abstract:
  Let $A_p(\C)$ be the space of entire functions such that $| f(z)|\le
Ae^{Bp(z)}$ for some $A,B>0$ and let $V$ be a discrete sequence of complex
numbers which is not a uniqueness set for $A_p(\C)$. We use $L^2$ estimates for
the $\bar\partial$ equation to charaterize the trace of $A_p(\C)$ on $V$.


title:
Performance Analysis of a Cross-layer Collaborative Beamforming Approach
  in the Presence of Channel and Phase Errors

abstract:
  Collaborative beamforming enables nodes in a wireless network to transmit a
common message over long distances in an energy efficient fashion. However, the
process of making available the same message to all collaborating nodes
introduces delays. The authors recently proposed a MAC-PHY cross-layer scheme
that enables collaborative beamforming with significantly reduced collaboration
overhead. The method requires knowledge of node locations and internode channel
coefficients. In this paper, the performance of that approach is studied
analytically in terms of average beampattern and symbol error probability (SEP)
under realistic conditions, i.e., when imperfect channel estimates are used and
when there are phase errors in the contributions of the collaborating nodes at
the receiver.


title: Activity spectrum from waiting-time distribution

abstract:
  In high frequency financial data not only returns but also waiting times
between trades are random variables. In this work, we analyze the spectra of
the waiting-time processes for tick-by-tick trades. The numerical problem,
strictly related with the real inversion of Laplace transforms, is analyzed by
using Tikhonov's regularization method. We also analyze these spectra by a
rough method using a comb of Dirac's delta functions.


title: Synchronization in Random Geometric Graphs

abstract:
  In this paper we study the synchronization properties of random geometric
graphs. We show that the onset of synchronization takes place roughly at the
same value of the order parameter that a random graph with the same size and
average connectivity. However, the dependence of the order parameter with the
coupling strength indicates that the fully synchronized state is more easily
attained in random graphs. We next focus on the complete synchronized state and
show that this state is less stable for random geometric graphs than for other
kinds of complex networks. Finally, a rewiring mechanism is proposed as a way
to improve the stability of the fully synchronized state as well as to lower
the value of the coupling strength at which it is achieved. Our work has
important implications for the synchronization of wireless networks, and should
provide valuable insights for the development and deployment of more efficient
and robust distributed synchronization protocols for these systems.


title: On a Dynamical Brauer-Manin Obstruction

abstract:
  Let F : X --> X be a morphism of a variety defined over a number field K, let
V be a K-subvariety of X, and let O_F(P)= {F^n(P) :n=0,1,2,...} be the orbit of
a point P in X(K). We describe a local-global principle for the intersection of
V and O_F(P). This principle may be viewed as a dynamical analog of the
Brauer-Manin obstruction. We show that the rational points of V(K) are
Brauer--Manin unobstructed for power maps on P^2 in two cases: (1) V is a
translate of a torus. (2) V is a line and P has a preperiodic coordinate. A key
tool in the proofs is the classical Bang-Zsigmondy theorem on primitive
divisors in sequences. We also prove analogous local-global results for
dynamical systems associated to endomoprhisms of abelian varieties.


title:
A model for reactive porous transport during re-wetting of hardened
  concrete

abstract:
  A mathematical model is developed that captures the transport of liquid water
in hardened concrete, as well as the chemical reactions that occur between the
imbibed water and the residual calcium silicate compounds residing in the
porous concrete matrix. The main hypothesis in this model is that the reaction
product -- calcium silicate hydrate gel -- clogs the pores within the concrete
thereby hindering water transport. Numerical simulations are employed to
determine the sensitivity of the model solution to changes in various physical
parameters, and compare to experimental results available in the literature.


title: Econometrics as Sorcery

abstract:
  The paper deals with the problem of identifying the internal dependencies and
similarities among a large number of random processes. Linear models are
considered to describe the relations among the time series and the energy
associated to the corresponding modeling error is the criterion adopted to
quantify their similarities. Such an approach is interpreted in terms of graph
theory suggesting a natural way to group processes together when one provides
the best model to explain the other. Moreover, the clustering technique
introduced in this paper will turn out to be the dynamical generalization of
other multivariate procedures described in literature.


title: Human Heuristics for Autonomous Agents

abstract:
  We investigate the problem of autonomous agents processing pieces of
information that may be corrupted (tainted). Agents have the option of
contacting a central database for a reliable check of the status of the
message, but this procedure is costly and therefore should be used with
parsimony. Agents have to evaluate the risk of being infected, and decide if
and when communicating partners are affordable. Trustability is implemented as
a personal (one-to-one) record of past contacts among agents, and as a
mean-field monitoring of the level of message corruption. Moreover, this
information is slowly forgotten in time, so that at the end everybody is
checked against the database. We explore the behavior of a homogeneous system
in the case of a fixed pool of spreaders of corrupted messages, and in the case
of spontaneous appearance of corrupted messages.


title:
Spatial-Spectral Joint Detection for Wideband Spectrum Sensing in
  Cognitive Radio Networks

abstract:
  Spectrum sensing is an essential functionality that enables cognitive radios
to detect spectral holes and opportunistically use under-utilized frequency
bands without causing harmful interference to primary networks. Since
individual cognitive radios might not be able to reliably detect weak primary
signals due to channel fading/shadowing, this paper proposes a cooperative
wideband spectrum sensing scheme, referred to as spatial-spectral joint
detection, which is based on a linear combination of the local statistics from
spatially distributed multiple cognitive radios. The cooperative sensing
problem is formulated into an optimization problem, for which suboptimal but
efficient solutions can be obtained through mathematical transformation under
practical conditions.


title:
Leggett's inequality, the before-before experiment, and free will on the
  part of Nature

abstract:
  The before-before experiment demonstrates free will acting from outside
space-time. The experimental violation of the Leggett's inequality supports the
view that it is not appropriate to attempt to limit this freedom in Nature by
forcing it to mimic classical features.


title:
Nonequilibrium Temperature and Thermometry in Heat-Conducting Phi-4
  Models

abstract:
  We analyze temperature and thermometry for simple nonequilibrium
heat-conducting models. We show in detail, for both two- and three-dimensional
systems, that the ideal gas thermometer corresponds to the concept of a local
instantaneous mechanical kinetic temperature. For the Phi-4 models investigated
here the mechanical temperature closely approximates the local thermodynamic
equilibrium temperature. There is a significant difference between kinetic
temperature and the nonlocal configurational temperature. Neither obeys the
predictions of extended irreversible thermodynamics. Overall, we find that
kinetic temperature, as modeled and imposed by the Nos\'e-Hoover thermostats
developed in 1984, provides the simplest means for simulating, analyzing, and
understanding nonequilibrium heat flows.


title:
Differentiability of M-functionals of location and scatter based on t
  likelihoods

abstract:
  The paper aims at finding widely and smoothly defined nonparametric location
and scatter functionals. As a convenient vehicle, maximum likelihood estimation
of the location vector m and scatter matrix S of an elliptically symmetric t
distribution on d-dimensional space with degrees of freedom larger than 1
extends to an M-functional defined on all probability distributions P in a
weakly open, weakly dense domain U. Here U consists of P not putting too much
mass in hyperplanes of dimension < d, as shown for empirical measures by Kent
and Tyler, Ann. Statist. 1991. It is shown here that (m,S) is analytic on U,
for the bounded Lipschitz norm, or for d=1, for the sup norm on distribution
functions. For k=1,2,..., and other norms, depending on k and more directly
adapted to t functionals, one has continuous differentiability of order k,
allowing the delta-method to be applied to (m,S) for any P in U, which can be
arbitrarily heavy-tailed. These results imply asymptotic normality of the
corresponding M-estimators (m_n,S_n). In dimension d=1 only, the t functionals
extend to be defined and weakly continuous at all t.


title: Markovian Memory Embedded in Two-State Natural Processes

abstract:
  Markovian memory embedded in a binary system is shaping its evolution on the
basis of its current state and introduces either clustering or dispersion of
binary states. The consequence is directly observed in the lengthening or
shortening of the runs of the same binary state and also in the way the
proportion of a state within a sequence of state measurements scatters about
its true average, which is quantifiable through the Markovian self-transition
probabilities. It is shown that the Markovian memory can even imitate the
evolution of a random process, regarding the long-term behavior of the
frequencies of its binary states. This situation occurs when the associated
binary state self-transition probabilities are balanced. To exemplify the
behavior of Markovian memory, two natural processes are selected. The first
example is studying the preferences of nonhuman troglodytes regarding
handedness. The Markovian model in this case assesses the extent of influence
two contiguous individuals may have on each other. The other example studies
the hindering of the quantum state transitions that rapid state measurements
introduce, known as the Quantum Zeno effect (QZE). Based on the current
methodology, simulations of the experimentally observed clustering of states
allowed for the estimation of the two self-transition probabilities in this
quantum system. Through these, one can appreciate how the particular hindering
of the evolution of a quantum state may have originated. The aim of this work
is to illustrate as merits of the current mathematical approach, its wide range
applicability and its potential to provide a variety of information regarding
the dynamics of the studied process.


title: Muon-Tau Symmetry and Leptogenesis in the Minimal Seesaw Model

abstract:
  The measured values for the mixture angles in neutrino oscillations suggest
the existence of a symmetry of interchange of flavor between muon and tau
neutrinos. Using this symmetry we analyzed the minimal seesaw model for
neutrino masses, where the Majorana mass was diagonalized, and it is
demonstrated that the model supports at most 3 CP violation phases and 5 real
masses at high energies. Nevertheless, at low energies, only 4 parameters of
mass and one relative Majorana CP phase remain. Therefore using the
experimental values of the masses square differences, the mixture angles and
the hierarchy, we can determine some parameters of the model but not all. Also
we propose the use of the parameter of baryonic asymmetry of the universe due
to leptogenesis to determine one more phase of the model. Finally we used a
normal hierarchy for the masses of the right handed neutrinos to make an
approximation, that allowed us to completely reconstruct the mass matrix for
left handed neutrinos. In special the value of mee is determined which can be
compared with the results of the neutrinoless double decay beta.


title: The Kondo effect of surface excitons

abstract:
  A recombination radiation line of real excitons in dense two-dimensional
electron gas at the [100] silicon surface is observed in luminescence spectra
of metal-oxide-semiconductor (MOS) structures. A new effect of anisotropic
paramagnetic reduction of the luminescence line indicates a strong influence of
the Kondo correlations on electron paramagnetism of the excitons.


title: Transient and Equilibrium Synchronization in Complex Neuronal Networks

abstract:
  Transient and equilibrium synchronizations in complex neuronal networks as a
consequence of dynamics induced by having sources placed at specific neurons
are investigated. The basic integrate-and-fire neuron is adopted, and the
dynamics is estimated computationally so as to obtain the activation at each
node along each instant of time. In the transient case, the dynamics is
implemented so as to conserve the total activation entering the system. In our
equilibrium investigations, the internally stored activation is limited to the
value of the respective threshold. The synchronization of the activation of the
network is then quantified in terms of its normalized entropy. The equilibrium
investigations involve the application of a number of complementary
characterization methods, including spectra and Principal Component Analysis,
as well as of an equivalent model capable of reproducing both the transient and
equilibrium dynamics. The potential of such concepts and measurements is
explored with respect to several theoretical models, as well as for the
neuronal network of \emph{C. elegans}. A series of interesting results are
obtained and discussed, including the fact that all models led to a transient
period of synchronization, whose specific features depend on the topological
structures of the networks. The investigations of the equilibrium dynamics
revealed a series of remarkable insights, including the relationship between
spiking oscillations and the hierarchical structure of the networks and the
identification of twin correlation patterns between node degree and total
activation, implying that hubs of connectivity are also hubs of
integrate-and-fire activation.


title: The self-compression of injected electron-hole plasma in silicon

abstract:
  A recombination radiation line of electron-hole plasma, observed in
electroluminescence spectra of tunneling silicon MOS diodes, has been
investigated at the temperature > 300 K. The internal quantum efficiency of the
luminescence, equal to 0.003, appears to be unexpectedly high. The spectral
position of the luminescence line indicates, that a weak overheating of the
diode by the diode current results in an anomalously strong reduction of the
semiconductor energy gap inside the electron-hole plasma. A unique threshold
optical hysteresis is observed in the luminescence intensity with changing
diode current. These results are explained by condensation of injected
electron-hole plasma into a dense state. A reduction of the semiconductor
energy gap due to generation of phonons by the plasma is discussed as a reason
of the plasma condensation. The plasma condensation is identified as the plasma
self-compression.


title: Connectivity of the space of ending laminations

abstract:
  We prove that for any closed surface of genus at least four, and any
punctured surface of genus at least two, the space of ending laminations is
connected. A theorem of E. Klarreich implies that this space is homeomorphic to
the Gromov boundary of the complex of curves. It follows that the boundary of
the complex of curves is connected in these cases, answering the conjecture of
P. Storm. Other applications include the rigidity of the complex of curves and
connectivity of spaces of degenerate Kleinian groups.


title: Genetic algorithm eclipse mapping

abstract:
  In this paper we analyse capabilities of eclipse mapping technique, based on
genetic algorithm optimization. To model of accretion disk we used the
"fire-flies" conception. This model allows us to reconstruct the distribution
of radiating medium in the disk using less number of free parameters than in
other methods. Test models show that we can achieve good approximation without
optimizing techniques.


title:
Spin density-functional theory for imbalanced interacting Fermi gases in
  highly elongated harmonic traps

abstract:
  We numerically study imbalanced two component Fermi gases with attractive
interactions in highly elongated harmonic traps. An accurate parametrization
formula for the ground state energy is presented for a spin-polarized
attractive Gaudin-Yang model. Our studies are based on an accurate microscopic
spin-density-functional theory through the Kohn-Sham scheme which employs the
one-dimensional homogeneous Gaudin-Yang model with Luther-Emery-liquid
ground-state correlation as a reference system. A Thomas-Fermi approximation is
examined incorporating the exchange-correlation interaction. By studying the
charge and spin density profiles of the system based on these methods, we gain
a quantitative understanding of the role of attractive interactions and
polarization on the formation of the two-shell structure, with the coexisted
Fulde-Ferrell-Larkin-Ovchinnikov-type phase in the center of the trap and
either the BCS superfluid phase or the normal phase at the edges of the trap.
Our results are in good agreement with the recent theoretical consequences.


title:
Orbital magnetization and its effects in spin-chiral ferromagnetic
  kagome lattice in the general spin-coupling region

abstract:
  The orbital magnetization and its effects on the two-dimensional kagom\'{e}
lattice with spin anisotropies included in the general Hund's coupling region
have been theoretically studied. The results show that the strength of the
Hund's coupling, as well as the spin chirality, contributes to the orbital
magnetization $\mathcal{M}$. Upon varying both these parameters, it is found
that the two parts of $\mathcal{M}$, i.e., the conventional part
$\mathbf{M}_{c}$ and the Berry-phase correction part $\mathbf{M}_{\Omega}$,
oppose each other. The anomalous Nernst conductivity is also calculated and a
peak-valley structure as a function of the electron Fermi energy is obtained.


title: Newton series and extended derivation relations for multiple $L$-values

abstract:
  We investigate Newton series for truncated multiple $L$-values and thereby
obtain a class of relations for multiple $L$-values. In addition, we give a
formulation and a proof of extended derivation relations for multiple
$L$-values.


title: $5D$ Solutions to $\Lambda$CDM Universe Derived from Global Brane Model

abstract:
  An exact solution of brane universe is studied and the result indicates that
Friedmann equations on the brane are modified with an extra term. This term can
play the role of dark energy and make the universe accelerate. In order to
derive the $\Lambda$CDM Universe from this global brane model, the new
solutions are obtained to describe the $5D$ manifold.


title:
Casimir Energy of 5D Electromagnetism and New Regularization Based on
  Minimal Area Principle

abstract:
  We examine the Casimir energy of 5D electromagnetism in the recent
standpoint. The bulk geometry is flat. Z$_2$ symmetry and the periodic
property, for the extra coordinate, are taken into account. After confirming
the consistency with the past result, we do new things based on a {\it new
regularization}. In the treatment of the divergences, we introduce IR and UV
cut-offs and {\it restrict} the (4D momentum, extra coordinate)-integral
region. The regularized configuration is the {\it sphere lattice}, in the 4D
continuum space, which changes along the extra coordinate. The change
(renormalization flow) is specified by the {\it minimal area principle}, hence
this regularization configuration is string-like. We do the analysis not in the
Kaluza-Klein expanded form but in a {\it closed} form. We do {\it not} use any
perturbation. The formalism is based on the heat-kernel approach using the {\it
position/momentum propagator}. Interesting relations between the heat-kernels
and the P/M propagators are obtained, where we introduce the {\it generalized}
P/M propagators. A useful expression of the Casimir energy, in terms of the P/M
propagator, is obtained. The restricted-region approach is replaced by the
weight-function approach in the latter-half description. Its meaning, in
relation to the {\it space-time quantization}, is argued. {\it Finite} Casimir
energy is numerically obtained. The compactification-size parameter
(periodicity) suffers from the renormalization effect. Numerical evaluation is
exploited. Especially the minimal surface lines in the 5D flat space are
obtained both numerically using the Runge-Kutta method and analytically using
the general solution.


title: Cut Elimination for a Logic with Generic Judgments and Induction

abstract:
  This paper presents a cut-elimination proof for the logic $LG^\omega$, which
is an extension of a proof system for encoding generic judgments, the logic
$\FOLDNb$ of Miller and Tiu, with an induction principle. The logic
$LG^\omega$, just as $\FOLDNb$, features extensions of first-order
intuitionistic logic with fixed points and a ``generic quantifier'', $\nabla$,
which is used to reason about the dynamics of bindings in object systems
encoded in the logic. A previous attempt to extend $\FOLDNb$ with an induction
principle has been unsuccessful in modeling some behaviours of bindings in
inductive specifications. It turns out that this problem can be solved by
relaxing some restrictions on $\nabla$, in particular by adding the axiom $B
\equiv \nabla x. B$, where $x$ is not free in $B$. We show that by adopting the
equivariance principle, the presentation of the extended logic can be much
simplified. This paper contains the technical proofs for the results stated in
\cite{tiu07entcs}; readers are encouraged to consult \cite{tiu07entcs} for
motivations and examples for $LG^\omega.$


title: Isotope coefficient of optimally doped high-Tc cuprates

abstract:
  Within the framework of pure BCS(i.e. when the critical temperature is
proportional to the Debye temperature), we show that the isotope coefficient is
always less than 1/2 and could be extremely small in polyatomic superconductors
depending on the chemical formula unit. This finding leads to quantitative
explanation of observed values(correct orders of magnitude and sometimes exact
numerical values) in optimally doped cuprates, magnesium diboride and
alkali-doped fullerenes. Consequently, the smallness of the isotope coefficient
is not only compatible with pure electron-phonon interaction, but this is
perhaps the rule in polyatomic systems.


title: Molecular dynamics simulation of multivalent ion mediated DNA attraction

abstract:
  All atom molecular dynamics simulations with explicit water were done to
study the interaction between two parallel double-stranded DNA molecules in the
presence of the multivalent counterions putrescine (2+), spermidine (3+),
spermine (4+) and cobalt hexamine (3+). The inter-DNA interaction potential is
obtained with the umbrella sampling technique. The attractive force is
rationalized in terms of the formation of ion bridges, i.e. multivalent ions
which are simultaneously bound to the two opposing DNA molecules. The lifetime
of the ion bridges is short on the order of a few nanoseconds.


title:
Competing effects of surface phonon softening and quantum size effects
  on the superconducting properties of nanostructured Pb

abstract:
  The superconducting transition temperature (TC) in nanostructured Pb remains
nearly constant as the particle size is reduced from 65 to 7nm, below which
size the superconductivity is lost rather abruptly. In contrast, there is a
large enhancement in the upper critical field (HC2) in the same size regime. We
explore the origin of the unusual robustness of the TC over such a large
particle size range in nanostructured Pb, by measuring the temperature
dependence of the superconducting energy gap in planar tunnel junctions of
Al/Al2O3/nano-Pb. We show that below 22nm, the electron phonon coupling
strength increases monotonically with decreasing particle size, and almost
exactly compensates for the quantum size effect, which is expected to suppress
TC.


title: Is there a Jordan geometry underlying quantum physics?

abstract:
  There have been several propositions for a geometric and essentially
non-linear formulation of quantum mechanics. From a purely mathematical point
of view, the point of view of Jordan algebra theory might give new strength to
such approaches: there is a ``Jordan geometry'' belonging to the Jordan part of
the algebra of observables, in the same way as Lie groups belong to the Lie
part. Both the Lie geometry and the Jordan geometry are well-adapted to
describe certain features of quantum theory. We concentrate here on the
mathematical description of the Jordan geometry and raise some questions
concerning possible relations with foundational issues of quantum theory.


title: Phase diagram of generalized fully frustrated XY model in two dimensions

abstract:
  It is shown that the phase diagram of the two-dimensional generalized
fully-frustrated XY model on a square lattice contains a crossing of the
chirality transition and the Kosterlitz-Thouless (KT) transition, as well as a
stable phase characterized by a finite helicity modulus $\Upsilon$ and an
unbroken chirality symmetry. The crossing point itself is consistent with a
critical point without any jump in $\Upsilon$, with the size ($L$) scaling $%
\Upsilon\sim L^{-0.63}$ and the critical index $\nu\approx0.77$. The KT
transition line remains continuous beyond the crossing but eventually turns
into a first-order line. The results are established using Monte-Carlo
simulations of the staggered magnetization, helicity modulus, and the
fourth-order helicity modulus.


title:
The OPE of the B-meson light-cone wavefunction for exclusive B decays:
  radiative corrections and higher-dimensional operators

abstract:
  We discuss the B-meson light-cone wavefunction relevant for QCD factorization
approach for exclusive B-meson decays. We derive the operator product expansion
for the B-meson light-cone wavefunction, taking into account the local
composite operators of dimension less than 6 and calculating the radiative
corrections at order \alpha_s for the corresponding Wilson coefficients. The
result embodies peculiar UV and IR behaviors of the B-meson light-cone
wavefunction, the Sudakov-type double logarithmic effects and the mixing of the
multiparticle states with additional gluons inside the B meson. The former
effects are induced from the cusp singularity in the radiative corrections,
while the latter is manifested by the participation of the higher-dimensional
operators associated with the nonperturbative structure of the B meson.


title: Hamiltonian elliptic dynamics on symplectic 4-manifolds

abstract:
  We consider C2 Hamiltonian functions on compact 4-dimensional symplectic
manifolds to study elliptic dynamics of the Hamiltonian flow, namely the
so-called Newhouse dichotomy. We show that for any open set U intersecting a
far from Anosov regular energy surface, there is a nearby Hamiltonian having an
elliptic closed orbit through U. Moreover, this implies that for far from
Anosov regular energy surfaces of a C2-generic Hamiltonian the elliptic closed
orbits are generic.


title:
Large Deviations Analysis for the Detection of 2D Hidden Gauss-Markov
  Random Fields Using Sensor Networks

abstract:
  The detection of hidden two-dimensional Gauss-Markov random fields using
sensor networks is considered. Under a conditional autoregressive model, the
error exponent for the Neyman-Pearson detector satisfying a fixed level
constraint is obtained using the large deviations principle. For a symmetric
first order autoregressive model, the error exponent is given explicitly in
terms of the SNR and an edge dependence factor (field correlation). The
behavior of the error exponent as a function of correlation strength is seen to
divide into two regions depending on the value of the SNR. At high SNR,
uncorrelated observations maximize the error exponent for a given SNR, whereas
there is non-zero optimal correlation at low SNR. Based on the error exponent,
the energy efficiency (defined as the ratio of the total information gathered
to the total energy required) of ad hoc sensor network for detection is
examined for two sensor deployment models: an infinite area model and and
infinite density model. For a fixed sensor density, the energy efficiency
diminishes to zero at rate O(area^{-1/2}) as the area is increased. On the
other hand, non-zero efficiency is possible for increasing density depending on
the behavior of the physical correlation as a function of the link length.


title: Irregular and singular loci of commuting varieties

abstract:
  We prove that the singular locus of the commuting variety of a noncommutative
reductive Lie algebra is contained in the irregular locus and we compute the
codimension of the latter. We prove that one of the irreducible components of
the irregular locus has codimension 4. This yields the lower bound of the
codimension of the singular locus, in particular, implies that it is at least
2. We also prove that the commuting variety is rational.


title: Circumnuclear Regions of Star Formation in Early Type Galaxies

abstract:
  Circumnuclear star forming regions, also called hotspots, are often found in
the inner regions of some spiral galaxies where intense processes of star
formation are taking place. In the UV, massive stars dominate the observed
circumnuclear emission even in the presence of an active nucleus, contributing
between 30 and 50% to the H$\beta$ total emission of the nuclear zone.
  Spectrophotometric data of moderate resolution (3000 < R < 11000) are
presented from which the physical properties of the ionized gas: electron
density, oxygen abundances, ionization structure etc. have been derived.


title: Free Differential Algebras, Rheonomy, and Pure Spinors

abstract:
  We report on progresses on the derivation of pure spinor constraints, BRST
algebra and BRST invariant sigma models a la pure spinors from the algebraic
structure of the FDA underlying supergravity.


title: Gravitational Lensing of Pregalactic 21 cm Radiation

abstract:
  Low-frequency radio observations of neutral hydrogen during and before the
epoch of cosmic reionization will provide hundreds of quasi-independent source
planes, each of precisely known redshift, if a resolution of ~ 1 arcminutes or
better can be attained. These planes can be used to reconstruct the projected
mass distribution of foreground material. A wide-area survey of 21 cm lensing
would provide very sensitive constraints on cosmological parameters, in
particular on dark energy. These are up to 20 times tighter than the
constraints obtainable from comparably sized, very deep surveys of galaxy
lensing although the best constraints come from combining data of the two
types. Any radio telescope capable of mapping the 21cm brightness temperature
with good frequency resolution (~ 0.05 MHz) over a band of width ~> 10 MHz
should be able to make mass maps of high quality. If the reionization epoch is
at z ~ 9 very large amounts of cosmological information will be accessible. The
planned Square Kilometer Array (SKA) should be capable of mapping the mass with
a resolution of a few arcminutes depending on the reionization history of the
universe and how successfully foreground sources can be subtracted. The
Low-Frequency Array (LOFAR) will be able to measure an accurate matter power
spectrum if the same conditions are met.


title:
Properties of the ionized gas of circumnuclear star-forming regions in
  early type spirals

abstract:
  (Abbr.) A study of cicumnuclear star-forming regions (CNSFRs) in several
early type spirals has been made in order to investigate their main properties:
stellar and gas kinematics, dynamical masses, ionising stellar masses, chemical
abundances and other properties of the ionised gas. Both high resolution (R$
\sim $20000) and moderate resolution (R ~ 5000) have been used.
  In some cases these regions, about 100 to 150 pc in size, are seen to be
composed of several individual star clusters with sizes between 1.5 and 4.9 pc
estimated from Hubble Space Telescope (HST) images. Stellar and gas velocity
dispersions are found to differ by about 20 to 30 km/s with the H$\beta$
emission lines being narrower than both the stellar lines and the [OIII]
$\lambda$ 5007 \AA lines. The twice ionized oxygen, on the other hand, shows
velocity dispersions comparable to those shown by stars. We have applied the
virial theorem to estimate dynamical masses of the clusters, assuming that
systems are gravitationally bounded and spherically symmetric, and using
previously measured sizes. The measured values of the stellar velocity
dispersions yield dynamical masses of the order of 10$^7$ to 10$^8$ solar
masses for the whole CNSFRs.
  ...


title: Subregular characters of the unitriangular group over a finite field

abstract:
  We present an explicit formula for subregular characters (i.e, irreducible
finite-dimensional complex characters of submaximal degree) of the
unitriangular group over a finite field of sufficiently large characteristic.


title: Instability of brane cosmological solutions with flux compactifications

abstract:
  We discuss the stability of the higher-dimensional de Sitter (dS) brane
solutions with two-dimensional internal space in the Einstein-Maxwel theory. We
show that an instability appears in the scalar-type perturbations with respect
to the dS spacetime. We derive a differential relation which has the very
similar structure to the ordinary laws of thermodynamics as an extension of the
work for the six-dimensional model [20]. In this relation, the area of dS
horizon (integrated over the two internal dimensions) exactly behaves as the
thermodynamical entropy. The dynamically unstable solutions are in the
thermodynamically unstable branch. An unstable dS compactification either
evolves toward a stable configuration or two-dimensional internal space is
decompactified. These dS brane solutions are equivalent to the accelerating
cosmological solutions in the six-dimensional Einstein-Maxwell-dilaton theory
via dimensional reduction. Thus, if the seed higher-dimensional solution is
unstable, the corresponding six-dimensional solution is also unstable. From the
effective four-dimensional point of view, a cosmological evolution from an
unstable cosmological solution in higher dimensions may be seen as a process of
the transition from the initial cosmological inflation to the current dark
energy dominated Universe.


title:
Kinematics of gas and stars in circumnuclear star-forming regions of
  early type spirals

abstract:
  (Abbr.) We present high resolution (R~20000) spectra in the blue and the far
red of cicumnuclear star-forming regions (CNSFRs) in three early type spirals
(NGC3351, NGC2903 and NGC3310) which have allowed the study of the kinematics
of stars and ionized gas in these structures and, for the first time, the
derivation of their dynamical masses for the first two. In some cases these
regions, about 100 to 150 pc in size, are seen to be composed of several
individual star clusters with sizes between 1.5 and 4.9 pc estimated from
Hubble Space Telescope (HST) images. The stellar dispersions have been obtained
from the Calcium triplet (CaT) lines at $\lambda\lambda$ 8494,8542,8662 \AA,
while the gas velocity dispersions have been measured by Gaussian fits to the
H$\beta$ and [OIII] $\lambda\lambda$ 5007 \AA lines on the high dispersion
spectra. Values of the stellar velocity dispersions are between 30 and 68 km/s.
We apply the virial theorem to estimate dynamical masses of the clusters,
assuming that systems are gravitationally bounded and spherically symmetric,
and using previously measured sizes. The measured values of the stellar
velocity dispersions yield dynamical masses of the order of 10$^7$ to 10$^8$
solar masses for the whole CNSFRs. Stellar and gas velocity dispersions are
found to differ by about 20 to 30 km/s with the H$\beta$ emission lines being
narrower than both the stellar lines and the [OIII] $\lambda\lambda$ 5007 \AA
lines. The twice ionized oxygen, on the other hand, shows velocity dispersions
comparable to those shown by stars, in some cases, even larger. We have found
indications of the presence of two different kinematical components in the
ionized gas of the regions...


title:
Proton elastic scattering from tin isotopes at 295 MeV and systematic
  change of neutron density distributions

abstract:
  Cross sections and analyzing powers for proton elastic scattering from
$^{116,118,120,122,124}$Sn at 295 MeV have been measured for a momentum
transfer of up to about 3.5 fm$^{-1}$ to deduce systematic changes of the
neutron density distribution. We tuned the relativistic Love-Franey interaction
to explain the proton elastic scattering of a nucleus whose density
distribution is well known. Then, we applied this interaction to deduce the
neutron density distributions of tin isotopes. The result of our analysis shows
the clear systematic behavior of a gradual increase in the neutron skin
thickness of tin isotopes with mass number.


title: Fixation and consensus times on a network: a unified approach

abstract:
  We investigate a set of stochastic models of biodiversity, population
genetics, language evolution and opinion dynamics on a network within a common
framework. Each node has a state, 0 < x_i < 1, with interactions specified by
strengths m_{ij}. For any set of m_{ij} we derive an approximate expression for
the mean time to reach fixation or consensus (all x_i=0 or 1). Remarkably in a
case relevant to language change this time is independent of the network
structure.


title: Mechanism of Anomalous Tunneling in Condensed Bose System

abstract:
  We clarify the origin of anomalous tunneling [Yu. Kagan et al. Phys. Rev.
Lett. 90 (2003) 130402] i.e. the perfect transmission at low energy limit of
tunneling of phonon excitations across the potential barrier separating two
Bose condensates. The perfect transmission is a consequence of the coincidence
of the wave function of the excited state at low energy limit and the
macroscopic wave function of the condensate. We show that the perfect
transmission at low energy occurs even at finite temperatures within the scheme
of Popov approximation.


title: Gravity, Cosmic Rays and the LHC

abstract:
  The high energy proton beams expected when the Large Hadron Collider (LHC)
comes online should provide a pass/fail test for a gravity-related explanation
of ultrahigh energy cosmic rays. The model predicts that particles have two
kinds energies, equal for null gravitational potentials and, in the potential
at the Earth, differing significantly above one TeV. If correct, a 7 TeV
trajectory energy proton at the LHC would deliver a 23.5 TeV particle state
energy in a collision.


title: Stability of K\"ahler-Ricci flow

abstract:
  We prove the convergence of K\"ahler-Ricci flow with some small initial
curvature conditions. As applications, we discuss the convergence of
K\"ahler-Ricci flow when the complex structure varies on a K\"ahler-Einstein
manifold.


title:
Soft gluon resummation in Drell-Yan dilepton production at small
  transverse momentum: spin asymmetry and a novel asymptotic formula

abstract:
  We discuss the double-spin asymmetry \aqt in the transversely polarized
Drell-Yan process at small transverse-momentum Q_T of the produced dilepton.
The soft gluon corrections relevant for small Q_T are resummed to all orders in
\alpha_s, up to the next-to-leading logarithmic accuracy. We show that the soft
gluon corrections largely cancel in the spin asymmetry, but the significant
corrections still remain.The asymmetries \aqt are calculated for pp collision
at RHIC and J-PARC, and for p\bar{p} collision at GSI. A novel asymptotic
formula for \aqt at small Q_T is presented, which provides a new approach to
extract the transversity \delta q(x) from the experimental data.


title:
On Steepest-Descent-Kaczmarz Methods for Regularizing Systems of
  Nonlinear Ill-posed Equations

abstract:
  We investigate modified steepest descent methods coupled with a loping
Kaczmarz strategy for obtaining stable solutions of nonlinear systems of
ill-posed operator equations. We show that the proposed method is a convergent
regularization method. Numerical tests are presented for a linear problem
related to photoacoustic tomography and a non-linear problem related to the
testing of semiconductor devices.


title: A Phenomenological Model for the Extended Zone Above AGB Stars

abstract:
  I suggest the existence of an extended zone above the surface of asymptotic
giant branch (AGB), as well as similar stars experiencing high mass loss rates.
In addition to the escaping wind, in this zone there are parcels of gas that do
not reach the escape velocity. These parcels of dense gas rise slowly and then
fall back. The wind and bound gas exist simultaneously to distances of ~100AU.
I term this region the effervescent zone. In this phenomenological study I find
that the density of the bound material in the effervescent zone falls as
~r^{-5/2}, not much faster than the wind density. The main motivation to
propose the effervescent model is to allow wide binary companions to influence
the morphology of the descendant planetary nebulae (PN) by accreting mass from
the effervescent zone. Accretion from the effervescent zone is more efficient
than accretion from the wind in forming an accretion disk around the companion.
The companion might then blow two jets that will shape the descendant PN.


title: Dynamical vacuum energy via adjustment mechanism

abstract:
  A new mechanism of adjustment of vacuum energy down to the observed value
from an initially huge one is considered. The mechanism is based on a very
strong variation of the gravitational coupling constant in very early universe.
The model predicts that the non--compensated remnant of vacuum energy changes
very slowly at late stages of the cosmological evolution and is naturally close
to the observed one. Asymptotically the effective vacuum energy tends to a
negative value, so the cosmological expansion should stop and turn into
contraction. There remains the problem of introduction of the usual matter into
the model and therefore realising realistic cosmology.


title:
Cryptoferromagnetism in Superconductors with Broken Time-Reversal
  Symmetry

abstract:
  The cryptoferromagnetic state (the state with intrinsic domain structure) in
superconducting ferromagnets subjected to external magnetic field is studied
theoretically. Ferromagnetism originates either from electron spin or the
intrinsic angular momentum of Cooper pairs (chiral p-wave superconductors like
$\mathrm{Sr_2 Ru O_4}$). The phase transitions towards the Meissner and the
mixed states are investigated, and the magnetic phase diagrams are obtained.
Cryptoferromagnetism, as a form coexistence of superconductivity and
ferromagnetism, can be detected by observation of magnetization curves
predicted in the present analysis.


title: Protostellar collapse: A comparison between SPH and AMR calculations

abstract:
  The development of parallel supercomputers allows today the detailed study of
the collapse and the fragmentation of prestellar cores with increasingly
accurate numerical simulations. Thanks to the advances in sub-millimeter
observations, a wide range of observed initial conditions enable us to study
the different modes of low-mass star formation. The challenge for the
simulations is to reproduce the observational results. Two main numerical
methods, namely AMR and SPH, are widely used to simulate the collapse and the
fragmentation of prestellar cores. We compare thoroughly these two methods
within their standard framework. We use the AMR code RAMSES and the SPH code
DRAGON. Our physical model is as simple as possible and consists of an
isothermal sphere rotating around the z-axis. We first study the conservation
of angular momentum as a function of the resolution. Then, we explore a wide
range of simulation parameters to study the fragmentation of prestellar cores.
There seems to be a convergence between the two methods, provided resolution in
each case is sufficient. Resolution criteria adapted to our physical cases, in
terms of resolution per Jeans mass, for an accurate description of the
formation of protostellar cores are deduced from the present study. This
convergence is encouraging for future work in simulations of low-mass star
formation, providing the aforementioned criteria are fulfilled.
  Higher resolution figures can be downloaded at
http://www-dapnia.cea.fr/Projets/COAST/paper_amrvssph.pdf


title: Induced quasi-actions: a remark

abstract:
  In this note we observe that the notion of an induced representation has an
analog for quasi-actions. We then use induced quasi-actions to refine some
earlier rigidity results for product spaces.


title: A lower bound for the Chung-Diaconis-Graham random process

abstract:
  Chung, Diaconis, and Graham considered random processes of the form
X_{n+1}=a_n X_n+b_n (mod p) where p is odd, X_0=0, a_n=2 always, and b_n are
i.i.d. for n=0,1,2,... . In this paper, we show that if
P(b_n=-1)=P{b_n=0)=P(b_n=1)=1/3, then there exists a constant c>1 such that c
log_2 p steps are not enough to make X_n get close to uniformly distributed on
the integers mod p.


title: Tunneling through Quantum Dots with Discrete Symmetries

abstract:
  We describe in this short review the influence of discrete symmetries in
complex quantum dots on the Kondo co-tunneling through these nano-objects.
These discrete symmetries stem from the geometrical structure of the tunneling
devices (e.g spatial symmetry of multivalley quantum dot in a tunneling contact
with leads). They affect the dynamical symmetry of spin multiplets
characterizing the ground state and excitations in quantum dots with definite
electron number occupation. The influence of external electric and magnetic
fields on these symmetries is examined, and analogies with the physics of
quantum tunneling through molecular complexes are discussed.


title: Bethe-Sommerfeld Conjecture

abstract:
  We consider Schroedinger operator $-\Delta+V$ in $R^d$ ($d\ge 2$) with smooth
periodic potential $V$ and prove that there are only finitely many gaps in its
spectrum.


title:
Auction-based Resource Allocation for Multi-relay Asynchronous
  Cooperative Networks

abstract:
  Resource allocation is considered for cooperative transmissions in
multiple-relay wireless networks. Two auction mechanisms, SNR auctions and
power auctions, are proposed to distributively coordinate the allocation of
power among multiple relays. In the SNR auction, a user chooses the relay with
the lowest weighted price. In the power auction, a user may choose to use
multiple relays simultaneously, depending on the network topology and the
relays' prices. Sufficient conditions for the existence (in both auctions) and
uniqueness (in the SNR auction) of the Nash equilibrium are given. The fairness
of the SNR auction and efficiency of the power auction are further discussed.
It is also proven that users can achieve the unique Nash equilibrium
distributively via best response updates in a completely asynchronous manner.


title: Robust Mixing for Ab-Initio Quantum Mechanical Calculations

abstract:
  We study the general problem of mixing for ab-initio quantum-mechanical
problems. Guided by general mathematical principles and the underlying physics,
we propose a multisecant form of Broydens second method for solving the
self-consistent field equations of Kohn-Sham density functional theory. The
algorithm is robust, requires relatively little finetuning and appears to
outperform the current state of the art, converging for cases that defeat many
other methods. We compare our technique to the conventional methods for
problems ranging from simple to nearly pathological.


title:
Gradient flow approach to geometric convergence analysis of
  preconditioned eigensolvers

abstract:
  Preconditioned eigenvalue solvers (eigensolvers) are gaining popularity, but
their convergence theory remains sparse and complex. We consider the simplest
preconditioned eigensolver--the gradient iterative method with a fixed step
size--for symmetric generalized eigenvalue problems, where we use the gradient
of the Rayleigh quotient as an optimization direction. A sharp convergence rate
bound for this method has been obtained in 2001--2003. It still remains the
only known such bound for any of the methods in this class. While the bound is
short and simple, its proof is not. We extend the bound to Hermitian matrices
in the complex space and present a new self-contained and significantly shorter
proof using novel geometric ideas.


title:
Detecting three-qubit bound MUB diagonal entangled states via Nonlinear
  optimal entanglement witnesses

abstract:
  One of the important approaches to detect quantum entanglement is using
linear entanglement witnesses EWs. In this paper, by determining the envelope
of the boundary hyper-planes defined by a family of linear EWs, a set of
powerful nonlinear optimal EWs is manipulated. These EWs enable us to detect
some three qubits bound MUB (mutually unbiased bases) diagonal entangled
states, i.e., the PPT (positive partial transpose) entangled states. Also, in
some particular cases, the introduced nonlinear optimal EWs are powerful enough
to separate the bound entangled regions from the separable ones. Finally, we
present numerical examples to demonstrate the practical accessibility of this
approach.
  Keywords :nonlinear optimal entanglement witnesses, mutually unbiased bases,
MUB diagonal states


title: Non-symplectic automorphisms of order 3 on K3 surfaces

abstract:
  In this paper we study K3 surfaces with a non-symplectic automorphism of
order 3. In particular, we classify the topological structure of the fixed
locus of such automorphisms and we show that it determines the action on
cohomology. This allows us to describe the structure of the moduli space and to
show that it has three irreducible components.


title: Balancing transparency, efficiency and security in pervasive systems

abstract:
  This chapter will survey pervasive computing with a look at how its
constraint for transparency affects issues of resource management and security.
The goal of pervasive computing is to render computing transparent, such that
computing resources are ubiquitously offered to the user and services are
proactively performed for a user without his or her intervention. The task of
integrating computing infrastructure into everyday life without making it
excessively invasive brings about tradeoffs between flexibility and robustness,
efficiency and effectiveness, as well as autonomy and reliability. As the
feasibility of ubiquitous computing and its real potential for mass
applications are still a matter of controversy, this chapter will look into the
underlying issues of resource management and authentication to discover how
these can be handled in a least invasive fashion. The discussion will be closed
by an overview of the solutions proposed by current pervasive computing
efforts, both in the area of generic platforms and for dedicated applications
such as pervasive education and healthcare.


title: Categorification of acyclic cluster algebras: an introduction

abstract:
  This is a concise introduction to Fomin-Zelevinsky's cluster algebras and
their links with the representation theory of quivers in the acyclic case. We
review the definition of cluster algebras (geometric, without coefficients),
construct the cluster category and present the bijection between cluster
variables and rigid indecomposable objects of the cluster category.


title: Limits on Planets Around White Dwarf Stars

abstract:
  We present limits on planetary companions to pulsating white dwarf stars. A
subset of these stars exhibit extreme stability in the period and phase of some
of their pulsation modes; a planet can be detected around such a star by
searching for periodic variations in the arrival time of these pulsations. We
present limits on companions greater than a few Jupiter masses around a sample
of 15 white dwarf stars as part of an on-going survey. One star shows a
variation in arrival time consistent with a 2 M_J planet in a 4.5 year orbit.
We discuss other possible explanations for the observed signal and conclude
that a planet is the most plausible explanation based on the data available.


title: Numerical primary decomposition

abstract:
  Consider an ideal $I \subset R = \bC[x_1,...,x_n]$ defining a complex affine
variety $X \subset \bC^n$. We describe the components associated to $I$ by
means of {\em numerical primary decomposition} (NPD).
  The method is based on the construction of {\em deflation ideal} $I^{(d)}$
that defines the {\em deflated variety} $\dXd$ in a complex space of higher
dimension. For every embedded component there exists $d$ and an isolated
component $\dYd$ of $\dId$ projecting onto $Y$. In turn, $\dYd$ can be
discovered by existing methods for prime decomposition, in particular, the {\em
numerical irreducible decomposition}, applied to $\dXd$.
  The concept of NPD gives a full description of the scheme $\Spec(R/I)$ by
representing each component with a {\em witness set}. We propose an algorithm
to produce a collection of witness sets that contains a NPD and that can be
used to solve the {\em ideal membership problem} for $I$.


title: Strain-induced Fermi contour anisotropy of GaAs 2D holes

abstract:
  We report measurements of magneto-resistance commensurability peaks, induced
by a square array of anti-dots, in GaAs (311)A two-dimensional holes as a
function of applied in-plane strain. The data directly probe the shapes of the
Fermi contours of the two spin subbands that are split thanks to the spin-orbit
interaction and strain. The experimental results are in quantitative agreement
with the predictions of accurate energy band calculations, and reveal that the
majority spin-subband has a severely distorted Fermi contour whose anisotropy
can be tuned with strain.


title: Approximation by light maps and parametric Lelek maps

abstract:
  The class of metrizable spaces $M$ with the following approximation property
is introduced and investigated: $M\in AP(n,0)$ if for every $\e>0$ and a map
$g\colon\I^n\to M$ there exists a 0-dimensional map $g'\colon\I^n\to M$ which
is $\e$-homotopic to $g$. It is shown that this class has very nice properties.
For example, if $M_i\in AP(n_i,0)$, $i=1,2$, then $M_1\times M_2\in
AP(n_1+n_2,0)$. Moreover, $M\in AP(n,0)$ if and only if each point of $M$ has a
local base of neighborhoods $U$ with $U\in AP(n,0)$. Using the properties of
AP(n,0)-spaces, we generalize some results of Levin and Kato-Matsuhashi
concerning the existence of residual sets of $n$-dimensional Lelek maps.


title:
Equivariant complex structures on homogeneous spaces and their cobordism
  classes

abstract:
  We consider compact homogeneous spaces G/H, where G is a compact connected
Lie group and H is its closed connected subgroup of maximal rank. The aim of
this paper is to provide an effective computation of the universal toric genus
for the complex, almost complex and stable complex structures which are
invariant under the canonical left action of the maximal torus T^k on G/H. As
it is known, on G/H we may have many such structures and the computations of
their toric genus in terms of fixed points for the same torus action give the
constraints on possible collections of weights for the corresponding
representations of T^k in the tangent spaces at the fixed points, as well as on
the signs at these points. In that context, the effectiveness is also
approached due to an explicit description of the relations between the weights
and signs for an arbitrary couple of such structures. Special attention is
devoted to the structures which are invariant under the canonical action of the
group G. Using classical results, we obtain an explicit description of the
weights and signs in this case. We consequently obtain an expression for the
cobordism classes of such structures in terms of coefficients of the formal
group law in cobordisms, as well as in terms of Chern numbers in cohomology.
These computations require no information on the cohomology ring of the
manifold G/H, but, on their own, give important relations in this ring. As an
application we provide an explicit formula for the cobordism classes and
characteristic numbers of the flag manifolds U(n)/T^n, Grassmann manifolds
G_{n,k}=U(n)/(U(k)\times U(n-k)) and some particular interesting examples.


title:
Long hitting time, slow decay of correlations and arithmetical
  properties

abstract:
  Let $\tau_r(x,x_0)$ be the time needed for a point $x$ to enter for the first
time in a ball $B_r(x_0)$ centered in $x_0$, with small radius $r$. We
construct a class of translations on the two torus having particular arithmetic
properties (Liouville components with intertwined denominators of convergents)
not satisfying a logarithm law, i.e. such that for generic $x,x_0$
\liminf_{r\to 0} \frac{\log \tau_r(x,x_0)}{-\log r} = \infty.
  By considering a suitable reparametrization of the flow generated by a
suspension of this translation, using a previous construction by Fayad, we show
the existence of a mixing system on three torus having the same properties. The
speed of mixing of this example must be subpolynomial, because we also show
that: in a system having polynomial decay of correlations the above ratio of
logarithms (which is also called the lower hitting time indicator) is bounded
(it is a function of the local dimension and the speed of correlation decay).
  More generally, this shows that reparametrizations of torus translations
having a Liouville component cannot be polynomially mixing.


title:
Experimental investigation of the residues produced in the 136Xe+Pb and
  124Xe+Pb fragmentation reactions at 1 A GeV

abstract:
  This paper presents the nuclide cross sections and the longitudinal velocity
distributions of residues produced in the reactions of 136Xe and 124Xe at 1 A
GeV in a lead target, measured at the high-resolution magnetic spectrometer,
the Fragment Separator (FRS) of GSI. The data cover a broad range of isotopes
of the elements between Z = 3 and Z = 56 for 136Xe and between Z = 5 and Z = 55
for 124Xe, reaching down to cross sections of a few microbarns. The velocity
distributions exhibit a Gaussian shape for masses above A = 20, while more
complex behaviour is observed for lighter masses. The isotopic distributions
for both reactions preserve a memory on the projectile N/Z ratio over the whole
residue mass range.


title:
Analysis of Estimation of Distribution Algorithms and Genetic Algorithms
  on NK Landscapes

abstract:
  This study analyzes performance of several genetic and evolutionary
algorithms on randomly generated NK fitness landscapes with various values of n
and k. A large number of NK problem instances are first generated for each n
and k, and the global optimum of each instance is obtained using the
branch-and-bound algorithm. Next, the hierarchical Bayesian optimization
algorithm (hBOA), the univariate marginal distribution algorithm (UMDA), and
the simple genetic algorithm (GA) with uniform and two-point crossover
operators are applied to all generated instances. Performance of all algorithms
is then analyzed and compared, and the results are discussed.


title: The Two User Gaussian Compound Interference Channel

abstract:
  We introduce the two user finite state compound Gaussian interference channel
and characterize its capacity region to within one bit. The main contributions
involve both novel inner and outer bounds. The inner bound is multilevel
superposition coding, but the decoding of the levels is opportunistic,
depending on the channel state. The genie aided outer bound is motivated by the
typical error events of the achievable scheme.


title: iBOA: The Incremental Bayesian Optimization Algorithm

abstract:
  This paper proposes the incremental Bayesian optimization algorithm (iBOA),
which modifies standard BOA by removing the population of solutions and using
incremental updates of the Bayesian network. iBOA is shown to be able to learn
and exploit unrestricted Bayesian networks using incremental techniques for
updating both the structure as well as the parameters of the probabilistic
model. This represents an important step toward the design of competent
incremental estimation of distribution algorithms that can solve difficult
nearly decomposable problems scalably and reliably.


title:
Thinking is Bad: Implications of Human Error Research for Spreadsheet
  Research and Practice

abstract:
  In the spreadsheet error community, both academics and practitioners
generally have ignored the rich findings produced by a century of human error
research. These findings can suggest ways to reduce errors; we can then test
these suggestions empirically. In addition, research on human error seems to
suggest that several common prescriptions and expectations for reducing errors
are likely to be incorrect. Among the key conclusions from human error research
are that thinking is bad, that spreadsheets are not the cause of spreadsheet
errors, and that reducing errors is extremely difficult.


title:
Evidence of N2-Ice On the Surface of the Icy Dwarf Planet 136472 (2005
  FY9)

abstract:
  We present high signal precision optical reflectance spectra of 2005 FY9
taken with the Red Channel Spectrograph and the 6.5-m MMT telescope on 2006
March 4 UT (5000 - 9500 A; 6.33 A pixel-1) and 2007 February 12 UT (6600 - 8500
A; 1.93 A pixel-1). From cross correlation experiments between the 2006 March 4
spectrum and a pure CH4-ice Hapke model, we find the CH4-ice bands in the MMT
spectrum are blueshifted by 3 +/- 4 A relative to bands in the pure CH4-ice
Hapke spectrum. The higher resolution MMT spectrum of 2007 February 12 UT
enabled us to measure shifts of individual CH4-ice bands. We find the 7296 A,
7862 A, and 7993 A CH4-ice bands are blueshifted by 4 +/- 2 A, 4 +/- 4 A, and 6
+/- 5 A. From four measurements we report here and one of our previously
published measurements, we find the CH4-ice bands are shifted by 4 +/- 1 A.
This small shift is important because it suggest the presence of another ice
component on the surface of 2005 FY9. Laboratory experiments show that CH4-ice
bands in spectra of CH4 mixed with other ices are blueshifted relative to bands
in spectra of pure CH4-ice. A likely candidate for the other component is
N2-ice because its weak 2.15 micron band and blueshifted CH4 bands are seen in
spectra of Triton and Pluto. Assuming the shift is due to the presence of N2,
spectra taken on two consecutive nights show no difference in CH4/N2. In
addition, we find no measureable difference in CH4/N2 at different depths into
the surface of 2005 FY9.


title: Enterprise Spreadsheet Management: A Necessary Good

abstract:
  This paper presents the arguments and supporting business metrics for
Enterprise Spreadsheet Management to be seen as a necessary good. These
arguments are divided into a summary of external business drivers that make it
necessary and the good that may be delivered to business spreadsheet users
involved in repetitive manual processes.


title:
A hierarchy of behavioral equivalences in the $\pi$-calculus with noisy
  channels

abstract:
  The $\pi$-calculus is a process algebra where agents interact by sending
communication links to each other via noiseless communication channels. Taking
into account the reality of noisy channels, an extension of the $\pi$-calculus,
called the $\pi_N$-calculus, has been introduced recently. In this paper, we
present an early transitional semantics of the $\pi_N$-calculus, which is not a
directly translated version of the late semantics of $\pi_N$, and then extend
six kinds of behavioral equivalences consisting of reduction bisimilarity,
barbed bisimilarity, barbed equivalence, barbed congruence, bisimilarity, and
full bisimilarity into the $\pi_N$-calculus. Such behavioral equivalences are
cast in a hierarchy, which is helpful to verify behavioral equivalence of two
agents. In particular, we show that due to the noisy nature of channels, the
coincidence of bisimilarity and barbed equivalence, as well as the coincidence
of full bisimilarity and barbed congruence, in the $\pi$-calculus does not hold
in $\pi_N$.


title: Spreadsheet Hell

abstract:
  This management paper looks at the real world issues faced by practitioners
managing spreadsheets through the production phase of their life cycle. It
draws on the commercial experience of several developers working with large
corporations, either as employees or consultants or contractors. It provides
commercial examples of some of the practicalities involved with spreadsheet use
around the enterprise.


title:
Categorisation of Spreadsheet Use within Organisations, Incorporating
  Risk: A Progress Report

abstract:
  There has been a significant amount of research into spreadsheets over the
last two decades. Errors in spreadsheets are well documented. Once used mainly
for simple functions such as logging, tracking and totalling information,
spreadsheets with enhanced formulas are being used for complex calculative
models. There are many software packages and tools which assist in detecting
errors within spreadsheets. There has been very little evidence of
investigation into the spreadsheet risks associated with the main stream
operations within an organisation. This study is a part of the investigation
into the means of mitigating risks associated with spreadsheet use within
organisations. In this paper the authors present and analyse three proposed
models for categorisation of spreadsheet use and the level of risks involved.
The models are analysed in the light of current knowledge and the general risks
associated with organisations.


title: Spaces of quasi-exponentials and representations of gl_N

abstract:
  We consider the action of the Bethe algebra B_K on (\otimes_{s=1}^k
L_{\lambda^{(s)}})_\lambda, the weight subspace of weight $\lambda$ of the
tensor product of k polynomial irreducible gl_N-modules with highest weights
\lambda^{(1)},...,\lambda^{(k)}, respectively. The Bethe algebra depends on N
complex numbers K=(K_1,...,K_N). Under the assumption that K_1,...,K_N are
distinct, we prove that the image of B_K in the endomorphisms of
(\otimes_{s=1}^k L_{\lambda^{(s)}})_\lambda is isomorphic to the algebra of
functions on the intersection of k suitable Schubert cycles in the Grassmannian
of N-dimensional spaces of quasi-exponentials with exponents K. We also prove
that the B_K-module (\otimes_{s=1}^k L_{\lambda^{(s)}})_\lambda is isomorphic
to the coregular representation of that algebra of functions. We present a
Bethe ansatz construction identifying the eigenvectors of the Bethe algebra
with points of that intersection of Schubert cycles.


title:
Quantum Hall Effect of Massless Dirac Fermions in a Vanishing Magnetic
  Field

abstract:
  The effect of strong long-range disorder on the quantization of the Hall
conductivity $\sigma_{xy}$ in graphene is studied numerically. It is shown that
increasing Landau-level mixing progressively destroys all plateaus in
$\sigma_{xy}$ except the plateaus at $\sigma_{xy}=\mp e^2/2h$ (per valley and
per spin). The critical state at the charge-neutral Dirac point is robust to
strong disorder and belongs to the universality class of the conventional
plateau transitions in the integer quantum Hall effect. We propose that the
breaking of time-reversal symmetry by ripples in graphene can realize this
quantum critical point in a vanishing magnetic field.


title: Helicity asymmetry of optically-pumped NMR spectra in GaAs

abstract:
  The origin of helicity asymmetries in the optically-pumped NMR signal and
hyperfine shift in GaAs is derived analytically and tested experimentally. The
ratio of the optically-pumped to the equilibrium electron polarizations is a
key parameter in determining both asymmetries. Variations in asymmetry with
photon energy and laser power reflect variations in the local temperature and
the electron spin polarization, and these two quantities are extracted from the
asymmetry through a simple methodology. Other contributions to the asymmetry
are considered.


title:
Charmless Two-body $B(B_s)\to VP$ decays In
  Soft-Collinear-Effective-Theory

abstract:
  We provide the analysis of charmless two-body $B\to VP$ decays under the
framework of the soft-collinear-effective-theory (SCET), where $V(P)$ denotes a
light vector (pseudoscalar) meson. Besides the leading power contributions,
some power corrections (chiraly enhanced penguins) are also taken into account.
Using the current available $B\to PP$ and $B\to VP$ experimental data on
branching fractions and CP asymmetry variables, we find two kinds of solutions
in $\chi^2$ fit for the 16 non-perturbative inputs which are essential in the
87 $B\to PP$ and $B\to VP$ decay channels. Chiraly enhanced penguins can change
several charming penguins sizably, since they share the same topology. However,
most of the other non-perturbative inputs and predictions on branching ratios
and CP asymmetries are not changed too much. With the two sets of inputs, we
predict the branching fractions and CP asymmetries of other modes especially
$B_s\to VP$ decays. The agreements and differences with results in QCD
factorization and perturbative QCD approach are analyzed. We also study the
time-dependent CP asymmetries in channels with CP eigenstates in the final
states and some other channels such as $\bar B^0/B^0\to\pi^\pm\rho^\mp$ and
$\bar B_s^0/B_s^0\to K^\pm K^{*\mp}$. In the perturbative QCD approach, the
$(S-P)(S+P)$ penguins in annihilation diagrams play an important role. Although
they have the same topology with charming penguins in SCET, there are many
differences between the two objects in weak phases, magnitudes, strong phases
and factorization properties.


title:
Coherence length of cosmic background radiation enlarges the attenuation
  length of the ultra-high energy proton

abstract:
  It is pointed out that an agreement of the one particle energy spectrum of
the cosmic background radiation (CMBR) with Plank distribution of 2.725 [K]
does not give a strong constraint on the coherence length of CMBR if the mean
free path of CMBR is very long. The coherence length in this situation is
estimated as a few times of $k_BT$. Due to this finite coherence length, the
attenuation length of ultra-high energy cosmic rays (UHECR) is reduced in the
$\Delta $ resonance region,i.e., around $10^{20}$ [eV]. The small attenuation
length makes the suppression of the flux of cosmic rays in this energy region
less prominent than the naive estimation


title:
High Resolution Observations using Adaptive Optics: Achievements and
  Future Needs

abstract:
  Over the last few years, several interesting observations were obtained with
the help of solar Adaptive Optics (AO). In this paper, few observations made
using the solar AO are enlightened and briefly discussed. A list of
disadvantages with the current AO system are presented. With telescopes larger
than 1.5m are expected during the next decade, there is a need to develop the
existing AO technologies for large aperture telescopes. Some aspects of this
development are highlighted. Finally, the recent AO developments in India are
also presented.


title:
Two Photon Exchange Contributions to Elastic e + p --> e + p Process in
  a Nonlocal Field Formalism

abstract:
  We compute the two photon exchange contributions to elastic scattering of
polarized electrons from target protons. We use a nonlocal field theory
formalism for this calculation. The formalism maintains gauge invariance and
provides a systematic procedure for making this calculation. The results depend
on one unknown parameter \bar b. We compute the two photon exchange correction
to the ratio of electric to magnetic form factors extracted using the
polarization transfer experiments. The correction is found to be small if \bar
b ~ 1. However for larger values of \bar b>3, the correction can be quite
significant. The correction to the polarization transfer results goes in the
right direction to explain their difference with the ratio measured by
Rosenbluth separation method. We find that the difference between the two
experimental results can be explained for a wide range of values of the
parameter \bar b. We also find that the corrections due to two photon exchange
depend on the photon longitudinal polarization epsilon. Hence we predict an
epsilon dependence of the form factor ratio extracted using the polarization
transfer technique. Finally we obtain a limit on \bar b by requiring that the
non-linearity in epsilon dependence of the unpolarized reduced cross section is
within experimental errors.


title: Phase Diagram of Cold Polarized Fermi Gas in Two Dimensions

abstract:
  The superfluid phase diagrams of a two-dimensional cold polarized Fermi gas
in the BCS-BEC crossover are systematically and analytically investigated. In
the BCS-Leggett mean field theory, the transition from unpolarized superfluid
phase to normal phase is always of first order. For a homogeneous system, the
two critical Zeeman fields and the critical population imbalance are
analytically determined in the whole coupling parameter region, and the
superfluid-normal mixed phase is shown to be the ground state between the two
critical fields. The density profile in the presence of a harmonic trap
calculated in the local density approximation exhibits a shell structure, a
superfluid core at the center and a normal shell outside. For weak interaction,
the normal shell contains a partially polarized cloud with constant density
difference surrounded by a fully polarized state. For strong interaction, the
normal shell is totally in fully polarized state with a density profile
depending only on the global population imbalance. The di-fermion bound states
can survive in the whole highly imbalanced normal phase.

categories: cond-mat.supr-con cond-mat.other cond-mat.str-el hep-ph nucl-th physics.atom-ph


title: On the Weakening of Chromospheric Magnetic Field in Active Regions

abstract:
  Simultaneous measurement of line-of-sight (LOS) magnetic and velocity fields
at the photosphere and chromosphere are presented. Fe I line at $\lambda6569$
and $H_{\alpha}$ at $\lambda6563$ are used respectively for deriving the
physical parameters at photospheric and chromospheric heights. The LOS magnetic
field obtained through the center-of-gravity method show a linear relation
between photospheric and chromospheric field for field strengths less than 700
G. But in strong field regions, the LOS magnetic field values derived from
$H_{\alpha}$ are much weaker than what one gets from the linear relationship
and also from those expected from the extrapolation of the photospheric
magnetic field. We discuss in detail the properties of magnetic field observed
in $H_{\alpha}$ from the point of view of observed velocity gradients. The
bisector analysis of $H_{\alpha}$ Stokes $I$ profiles show larger velocity
gradients in those places where strong photospheric magnetic fields are
observed. These observations may support the view that the stronger fields
diverge faster with height compared to weaker fields.


title:
Spectrum of Curvature Perturbation of Multi-field Inflation with
  Small-Field Potential

abstract:
  In this paper, we have studied the spectrum of curvature perturbation of
multi-field inflation with general small-field potential. We assume that the
isocurvature perturbation may be neglected, and by using the Sasaki-Stewart
formalism, we found that the spectrum may be redder or bluer than of its
corresponding single field. The result depends upon the values of fields and
their effective masses at the horizon-crossing time. We discuss the relevant
cases.


title: The Decay of Dirac Hair around a Dilaton Black Hole

abstract:
  The intermediate and late-time behaviour of a massive Dirac field in the
background of static spherically symmetric black hole solutions is
investigated. The intermediate asymptotic behaviour of a massive Dirac field
depends on the mass parameter as well as the wave number of the mode, while the
late time behaviour has a power law decay rate independent of both.


title:
Density-induced suppression of the alpha-particle condensate in nuclear
  matter and the structure of alpha cluster states in nuclei

abstract:
  At low densities, with decreasing temperatures, in symmetric nuclear matter
alpha-particles are formed, which eventually give raise to a quantum condensate
with four-nucleon alpha-like correlations (quartetting). Starting with a model
of alpha-matter, where undistorted alpha particles interact via an effective
interaction such as the Ali-Bodmer potential, the suppression of the condensate
fraction at zero temperature with increasing density is considered. Using a
Jastrow-Feenberg approach, it is found that the condensate fraction vanishes
near saturation density. Additionally, the modification of the internal state
of the alpha particle due to medium effects will further reduce the condensate.
  In finite systems, an enhancement of the S state wave function of the c.o.m.
orbital of alpha particle motion is considered as the correspondence to the
condensate. Wave functions have been constructed for self-conjugate 4n nuclei
which describe the condensate state, but are fully antisymmetrized on the
nucleonic level. These condensate-like cluster wave functions have been
successfully applied to describe properties of low-density states near the n
alpha threshold. Comparison with OCM calculations in 12C and 16O shows strong
enhancement of the occupation of the S-state c.o.m. orbital of the
alpha-particles. This enhancement is decreasing if the baryon density
increases, similar to the density-induced suppression of the condensate
fraction in alpha matter. The ground states of 12C and 16O show no enhancement
at all, thus a quartetting condensate cannot be formed at saturation densities.


title: Study of Charmonium(-like) States via ISR at Belle

abstract:
  The cross sections for e+e- to pi+pi-J/psi, pi+pi-psi(2S), K+K-J/psi, DDbar,
DDbar pi, D*Dbar, and D*D*bar are measured using data sample collected on or
near the Upsilon(4S) resonance with the Belle detector at KEKB. A peak near
4.25 GeV/c^2, corresponding to the so called Y(4260), is observed in
pi+pi-J/psi final state. In addition, there is another cluster of events at
around 4.05 GeV/c^2. Two resonant structures are observed in the pi+pi-psi(2S)
invariant mass distribution, one at 4361+-9+-9 MeV/c^2 with a width of
74+-15+-10 MeV/c^2, and another at 4664+-11+-5 MeV/c^2 with a width of
48+-15+-3 MeV/c^2. The rich structures observed in all these final states
indicate that our understanding of the vector charmonium states above the open
charm threshold is still poor, let alone the other possible dynamics such as
charmonium hybrids or final state re-scattering and so on.


title: The MOND paradigm

abstract:
  I review briefly different aspects of the MOND paradigm, with emphasis on
phenomenology, epitomized here by many MOND laws of galactic motion--analogous
to Kepler's laws of planetary motion. I then comment on the possible roots of
MOND in cosmology, possibly the deepest and most far reaching aspect of MOND.
This is followed by a succinct account of existing underlying theories. I also
reflect on the implications of MOND's successes for the dark matter (DM)
paradigm: MOND predictions imply that baryons alone accurately determine the
full field of each and every individual galactic object. This conflicts with
the expectations in the DM paradigm because of the haphazard formation and
evolution of galactic objects and the very different influences that baryons
and DM are subject to during the evolution, as evidenced, e.g., by the very
small baryon-to-DM fraction in galaxies (compared with the cosmic value). All
this should disabuse DM advocates of the thought that DM will someday be able
to reproduce MOND: It is inconceivable that the modicum of baryons left over in
galaxies can be made to determine everything if a much heavier DM component is
present.


title: Comment on Magnetic Monopole Excitations in Spin Ice

abstract:
  It has been proposed recently \cite{son} that excitations in Spin Ice can be
of the form of magnetic monopoles that does not obey the Dirac Quantization
Condition. It is also well known \cite{rj} that the above scenario leads to
non-associativity among translation generators. It will be interesting to see
how the monopole picture in Spin Ice survives in the light of the latter
observation.


title: First principles study on the spin transfer torques

abstract:
  An efficient first principles method was developed to calculate spin transfer
torques in layered system with noncollinear magnetization. The complete
scattering wave function is determined by matching the wave function in the
scattering region with the Bloch states in the leads. The spin transfer torques
are obtained with aid of the scattering wave function. We applied our method to
the ferromagnetic spin valve and found that the material (Co, Ni and Ni80Fe20)
dependence of the spin transfer torques could be well understood by the Fermi
surface. Ni has much longer spin injection penetration length than Co.
Interfacial disorder is also considered. It is found that the spin transfer
torques could be enhanced by the interfacial disorder in some system.