title:
Dirac equation description on the electronic states and magnetic
  properties of a square graphene quantum dot

abstract:
  Electronic eigen-states of a square graphene quantum dot(GQD) terminated by
both zigzag and armchair edges are derived in the theoretical framework of
Dirac equation. We find that the Dirac equation can determine the eigen-energy
spectrum of a GQD with high accuracy even if its size is reduced to a few
nanometers. More importantly, from the Dirac equation description we can
readily work out the number and energy gap of the conjugate surface states,
which are intimately associated with the magnetic properties of the GQD. By
using the Hartree-Fock mean field approach, we study the size dependence of the
magnetic ordering formation in this square GQD. We find that there exists a
critical size of the width between the two zigzag edges to indicate the onset
of the stable magnetic ordering. On the other hand, when such a width increases
further, the magnetic ground state energy of a charge neutral GQD tends to a
saturated value. These results coincide with the previous results obtained from
the first principle calculation. Then, based on the Dirac equation solution
about the surface state, we establish a simple two-state model which can
quantitatively explain the size dependence of the magnetic ordering in the
square GQD.


title:
Non-monotonic density dependence of the diffusion of DNA fragments in
  low-salt suspensions

abstract:
  The high linear charge density of 20-base-pair oligomers of DNA is shown to
lead to a striking non-monotonic dependence of the long-time self-diffusion on
the concentration of the DNA in low-salt conditions. This generic non-monotonic
behavior results from both the strong coupling between the electrostatic and
solvent-mediated hydrodynamic interactions, and from the renormalization of
these electrostatic interactions at large separations, and specifically from
the dominance of the far-field hydrodynamic interactions caused by the strong
repulsion between the DNA fragments.


title: The AMS-02 Anticoincidence Counter

abstract:
  The AMS-02 detector will measure cosmic rays on the International Space
Station. This contribution will cover production, testing, space qualification
and integration of the AMS-02 anticoincidence counter. The anticoincidence
counter is needed to to assure a clean track reconstruction for the charge
determination and to reduce the trigger rate during periods of high flux.


title: Results of MAGIC on Galactic sources

abstract:
  MAGIC is a single-dish Cherenkov telescope located on La Palma (Spain), hence
with an optimal view on the Northern sky. Sensitive in the 30 GeV-30 TeV energy
band, it is nowadays the only ground-based instrument being able to measure
high-energy gamma-rays below 100 GeV. We review the most recent experimental
results on Galactic sources obtained using MAGIC. These include pulsars, binary
systems, supernova remnants and unidentified sources.


title: Focusing versus defocusing properties of truly naked black holes

abstract:
  We study the properties of the congruence of null geodesics propagating near
the so-called truly naked horizons (TNH) - objects having finite Kretschmann
scalar but with diverging tidal acceleration for freely falling observers. The
expansion of outgoing rays near the future horizon always tends to vanish for
the non-extremal case but may be non-zero for the distorted (ultra)extremal
one. It tends to diverge for the ingoing ones if the the null energy condition
(NEC) is satisfied in the vicinity of the horizon outside. However, it also
tends to zero for NEC violating cases except the remote horizons. We also
discuss the validity of test particle approximation for TNHs and find the
sufficient condition for backreaction remaining small.


title:
Coherent Activation of Zero-Field Fiske Modes in Arrays of Josephson
  Junctions

abstract:
  Series arrays of Josephson junctions show evidence of a mode in which all the
junctions oscillate in synchronism on voltage resonances appearing, in zero
external magnetic field, at multiples of the fundamental Fiske step spacing.
The measurements show that the current amplitude of the resonances increases
linearly as their voltages are summed. Investigation of the nature of the
coherent mode by magnetic field responses of arrays and isolated juctions
reveals that the oscillations take place in a parameter plane region where dc
magnetic fields only activate boundary current and flux-quanta dynamics can
take place.


title: On the entropy flows to disorder

abstract:
  Gamma distributions, which contain the exponential as a special case, have a
distinguished place in the representation of near-Poisson randomness for
statistical processes; typically, they represent distributions of spacings
between events or voids among objects. Here we look at the properties of the
Shannon entropy function and calculate its corresponding flow curves. We
consider univariate and bivariate gamma, as well as Weibull distributions which
also include exponential distributions.


title: A topology for the penumbral magnetic fields

abstract:
  We describe a scenario for the sunspot magnetic field topology that may
account for recent observations of upflows and downflows in penumbrae.
According to our conjecture, short narrow magnetic loops fill the penumbral
volume. Flows along these field lines are responsible for both the Evershed
effect and the convective transport. This scenario seems to be qualitatively
consistent with most existing observations, including the dark cores in
penumbral filaments reported by Scharmer et al. Each bright filament with dark
core would be a system of two paired convective rolls with the dark core
tracing the lane where the plasma sinks down. The magnetic loops would have a
hot footpoint in one of the bright filament and a cold footpoint in the dark
core. The scenario also fits in most of our theoretical prejudices (siphon
flows along field lines, presence of overturning convection, drag of field
lines by downdrafts, etc). If the conjecture turns out to be correct, the mild
upward and downward velocities observed in penumbrae must increase upon
improvement of the current spatial resolution. This and other observational
tests to support or disprove the proposed scenario are put forward.


title:
Theoretical study of the stable states of small carbon clusters Cn (n =
  2-10)

abstract:
  Both even- and odd-numbered neutral carbon clusters Cn (n = 2-10) are
systematically studied using the energy minimization method and the modified
Brenner potential for the carbon-carbon interactions. Many stable
configurations were found and several new isomers are predicted. For the lowest
energy stable configurations we obtained their binding energies and bond
lengths. We found that for n < 6 the linear isomer is the most stable one while
for n > 5 the monocyclic isomer becomes the most stable. The latter was found
to be regular for all studied clusters. The dependence of the binding energy
for linear and cyclic clusters versus the cluster size n (n = 2-10) is found to
be in good agreement with several previous calculations, in particular with ab
initio calculations as well as with experimental data for n = 2-5.


title: Linear stochastic systems: a white noise approach

abstract:
  Using the white noise setting, in particular the Wick product, the Hermite
transform, and the Kondratiev space, we present a new approach to study linear
stochastic systems, where randomness is also included in the transfer function.
We prove BIBO type stability theorems for these systems, both in the discrete
and continuous time cases. We also consider the case of dissipative systems for
both discrete and continuous time systems. We further study $\ell_1$-$\ell_2$
stability in the discrete time case, and ${\mathbf L}_2$-${\mathbf L}_\infty$
stability in the continuous time case.


title:
Three-dimensional simulations of multiple protoplanets embedded in a
  protostellar disc

abstract:
  Protoplanet eccentricities of e >~ H/r can slow or reverse migration, but
previous 2D studies have shown that gravitational scattering cannot maintain
significant planet eccentricities against disc-induced damping. We simulate the
evolution of low-mass protoplanetary swarms in three dimensions. The aim is to
examine both protoplanet survival rates and the dynamical structure of the
resulting planetary systems, and to compare them with 2D simulations. We
present results from a 3D hydrodynamic simulation of eight protoplanets
embedded in a protoplanetary disc. We also present a suite of simulations
performed using an N-body code, modified to include prescriptions for planetary
migration and for eccentricity and inclination damping. These prescriptions
were obtained by fitting analytic formulae to hydrodynamic simulations of
planets embedded in discs with initially eccentric and/or inclined orbits. As
was found in two dimensions, differential migration produces groups of
protoplanets in stable, multiple mean-motion resonances that migrate in
lockstep, preventing prolonged periods of gravitational scattering. In almost
all simulations, this leads to large-scale migration of the protoplanet swarm
into the central star in the absence of a viable stopping mechanism. The
evolution involves mutual collisions, occasional instances of large-scale
scattering, and the frequent formation of the long-lived, co-orbital planet
systems that arise in > 30% of all runs. Disc-induced damping overwhelms
eccentricity and inclination growth due to planet-planet interactions.
Co-orbital planets are a natural outcome of dynamical relaxation in a strongly
dissipative environment, and if observed in nature would imply that such a
period of evolution commonly arises during planetary formation.


title:
Magnetic Field Induced Coherence-Incoherence Crossover in the Interlayer
  Conductivity of a Layered Organic Metal

abstract:
  The angle-dependent interlayer magnetoresistance of the layered organic metal
$\alpha$-(BEDT-TTF)$_2$KHg(SCN)$_4$ is found to undergo a dramatic change from
the classical conventional behavior at low magnetic fields to an anomalous one
at high fields. This field-induced crossover and its dependence on the sample
purity and temperature imply the existence of two parallel channels in the
interlayer transport: a classical Boltzmann conductivity $\sigma_{c}$ and an
incoherent channel $\sigma_{i}$. We propose a simple model for $\sigma_{i}$
explaining its metallic temperature dependence and low sensitivity to the
inplane field component.


title: Ensuring Query Compatibility with Evolving XML Schemas

abstract:
  During the life cycle of an XML application, both schemas and queries may
change from one version to another. Schema evolutions may affect query results
and potentially the validity of produced data. Nowadays, a challenge is to
assess and accommodate the impact of theses changes in rapidly evolving XML
applications.
  This article proposes a logical framework and tool for verifying
forward/backward compatibility issues involving schemas and queries. First, it
allows analyzing relations between schemas. Second, it allows XML designers to
identify queries that must be reformulated in order to produce the expected
results across successive schema versions. Third, it allows examining more
precisely the impact of schema changes over queries, therefore facilitating
their reformulation.


title: The Fate of the Sound and Diffusion in Holographic Magnetic Field

abstract:
  It was shown in arXiv:0810.4094 [hep-th] that in the presence of the magnetic
field the sound waves in (2+1) dimensional plasma disappear and are replaces by
a diffusive mode. Similarly, the shear and charge diffusion fluctuations form a
subdiffusive mode. However, since the limit of small magnetic field does not
commute with the hydrodynamic limit it is not obvious whether or not these
modes are stable under higher order corrections. Using AdS/CFT correspondence
we show that in the case of M2-brane plasma these modes do exist as we find the
corresponding supergravity solutions. This allowed us to compute the
conductivity and the shear viscosity to all orders in magnetic field. We find
that the viscosity to entropy ratio saturates the Kovtun-Son-Starinets bound.
This extends the universality property of the shear viscosity to the case of
the strongly coupled plasma in external magnetic field.


title: Stable pairs on elliptic K3 surfaces

abstract:
  We study semistable pairs on elliptic K3 surfaces with a section: we
construct a family of moduli spaces of pairs, related by wall crossing
phenomena, which can be studied to describe the birational correspondence
between moduli spaces of sheaves of rank 2 and Hilbert schemes on the surface.
In the 4-dimensional case, this can be used to get the isomorphism between the
moduli space and the Hilbert scheme described by Friedman.


title: Spin currents in diluted magnetic semiconductors (extended version)

abstract:
  Spin currents resulting in the zero-bias spin separation have been observed
in unbiased diluted magnetic semiconductor structures (Cd,Mn)Te/(Cd,Mg)Te. The
pure spin current generated due to the electron gas heating by terahertz
radiation is converted into a net electric current by application of an
external magnetic field. We demonstrate that polarization of the magnetic ion
system enhances drastically the conversion due to the spin-dependent scattering
by localized Mn(2+) ions and the giant Zeeman splitting.


title:
On the competition between the mirror and electromagnetic ion cyclotron
  modes

abstract:
  We give a simple argument for the exclusive existence of mirror and
electromaghetic ion cyclotron modes in anisotropic high-$\beta$ plasmas. It is
shown that, in addition to a large domain of coexistence of both modes, two
domains exist in parameter space $(A,\beta_\perp)$ where solely either mirror
modes or electromagnetic ion cyclotron modes can be excited. In the overlap
region the modes with the larger growth rate should win. However nonlinear
effects may modify such a conclusion.


title: Early Universe: inflation and cosmological perturbations

abstract:
  After a brief summary of general relativity and cosmology, we present the
basic concepts underlying inflation, the currently best motivated models for
the early Universe. We describe the simplest inflation models, based on a
single scalar field, and discuss how primordial cosmological perturbations are
generated. We then review some recent developments concerning multi-field
inflation models, in particular multi-field Dirac-Born-Infeld inflation.


title:
Bipolar charge-carrier injection in semiconductor/insulator/conductor
  heterostructures: self-consistent consideration

abstract:
  A self-consistent model of bipolar charge-carrier injection and transport
processes in a semiconductor/insulator/conductor system is developed which
incorporates space-charge effects in the description of the injection process.
The amount of charge-carriers injected is strongly determined by the energy
barrier emerging at the contact, but at the same time the electrostatic
potential generated by the injected charge-carriers modifies the height of this
injection barrier itself. In our model, self-consistency is obtained by
assuming continuity of the electric displacement and of the electrochemical
potential all over the system. The constituents of the system are properly
taken into account by means of their respective density of state distributions.
The consequences resulting from our model are discussed on the basis of an
indium tin oxide/organic semiconductor/conductor structure. The distributions
of the charge carriers and the electric field through the electrodes and the
organic layer are calculated. The recombination- and current-voltage
characteristics are analyzed for different heights of injection barriers and
varying values of the recombination rate and compared with the measured
current-voltage dependences for an indium tin oxide/poly(phenylene vinylene)/Ca
structure. The voltage dependences of the recombination efficiency for the
different values of injection barriers and recombination rate reveal optimum
conditions for the device performance.


title: The removal of critical slowing down

abstract:
  We present promising initial results of our adaptive multigrid solver
developed for application directly to the non-Hermitian Wilson-Dirac system in
4 dimensions, as opposed to the solver developed in [1] for the corresponding
normal equations. The key behind the success of this algorithm is the use of an
adaptive projection onto coarse grids that preserves the near null space of the
system matrix. We demonstrate that the resulting algorithm has weak dependence
on the gauge coupling and exhibits extremely mild critical slowing down in the
chiral limit.


title:
UCN production by multiphonon processes in superfluid Helium under
  pressure

abstract:
  Cold neutrons are converted to ultra-cold neutrons (UCN) by the excitation of
a single phonon or multiphonons in superfluid helium. The dynamic scattering
function S(q, omega) of the superfluid helium strongly depends on pressure,
leading to a pressure- dependent differential UCN production rate. A
phenomenological expression for the multiphonon part of the scattering function
s(lambda) describing UCN production has been derived from inelastic neutron
scattering data. When combined with the production rate from single phonon
processes this allows us to calculate the UCN production for any incident
neutron flux. For calculations of the UCN production from single phonon
processes we propose to use the values for S*(SVP) = 0.118(8) and S*(20 bar) =
0.066(6). As an example we will calculate the expected UCN production rate at
the cold neutron beam for fundamental physics PF1b at the Institut Laue
Langevin. We conclude that UCN production in superfluid helium under pressure
is not attractive.


title: Coherence properties of the microcavity polariton condensate

abstract:
  A theoretical model is presented which explains the dominant decoherence
process in a microcavity polariton condensate. The mechanism which is invoked
is the effect of self-phase modulation, whereby interactions transform
polariton number fluctuations into random energy variations. The model shows
that the phase coherence decay, g1(t), has a Kubo form, which can be Gaussian
or exponential, depending on whether the number fluctuations are slow or fast.
This fluctuation rate also determines the decay time of the intensity
correlation function, g2(t), so it can be directly determined experimentally.
The model explains recent experimental measurements of a relatively fast
Gaussian decay for g1(t), but also predicts a regime, further above threshold,
where the decay is much slower.


title: On modified tachyon DBI action

abstract:
  Recently a modification of the tachyon DBI action has been proposed in which
the tachyon carries the internal CP matrix \sigma_1 and \sigma_2. In this
paper, we find the momentum expansion of the disk level S-matrix element of
four tachyons and one gauge field in superstring theory and show that the first
and second order terms of the expansion are in perfect agreement with the above
tachyon DBI action.


title:
Superconductivity on the density wave background with soliton-wall
  structure

abstract:
  Superconductivity (SC) may microscopically coexist with density wave (DW)
when the nesting of the Fermi surface (FS) is not perfect. There are, at least,
two possible microscopic structures of a DW state with quasi-particle states
remaining on the Fermi level and leading to the Cooper instability: (i) the
soliton-wall phase and (ii) the small ungapped Fermi-surface pockets. The
dispersion of such quasi-particle states strongly differs from that without DW,
and so do the properties of SC on the DW background. The upper critical field
$H_{c2}$ in such a SC state strongly increases as the system approaches the
critical pressure, where superconductivity first appears. $H_{c2}$ may
considerably exceed its typical value without DW and has unusual upward
curvature as function of temperature. The results obtained explain the
experimental observations in layered organic superconductors
(TMTSF)$_{2}$PF$_{6}$ and $\alpha $-(BEDT TTF)$_{2}$KHg(SCN)$_{4}$.


title:
Invariants of stationary AF-algebras and torsion subgroup of elliptic
  curves with complex multiplication

abstract:
  Let G(A) be an AF-algebra given by periodic Bratteli diagram with the
incidence matrix A in GL(n, Z). For a given polynomial p(x) in Z[x] we assign
to G(A) a finite abelian group Z^n/p(A) Z^n. It is shown that if p(0)=1 or
p(0)=-1 and Z[x]/(p(x)) is a principal ideal domain, then Z^n/p(A) Z^n is an
invariant of the strong stable isomorphism class of G(A). For n=2 and p(x)=x-1
we conjecture a formula linking values of the invariant and torsion subgroup of
elliptic curves with complex multiplication.


title:
Nonlinear dynamics of a cigar-shaped Bose-Einstein condensate coupled
  with a single cavity mode

abstract:
  We investigate the nonlinear dynamics of a combined system which is composed
of a cigar-shaped Bose-Einstein condensate and an optical cavity. The two sides
couple dispersively. This system is characterized by its nonlinearity: after
integrating out the freedom of the cavity mode, the potential felt by the
condensate depends on the condensate itself. We develop a discrete-mode
approximation for the condensate. Based on this approximation, we map out the
steady configurations of the system. It is found that due to the nonlinearity
of the system, the nonlinear levels of the system can fold up in some parameter
regimes. That will lead to the breakdown of adiabaticity. Analysis of the
dynamical stability of the steady states indicates that the same level
structure also results in optical bistability.


title:
Ab initio electronic structure calculation of hollandite vanadate
  K$_2$V$_8$O$_{16}$

abstract:
  An \textit{ab initio} electronic structure calculation based on the
generalized gradient approximation in the density functional theory is carried
out to study the basic electronic states of hollandite vanadate
K$_2$V$_8$O$_{16}$. We find that the states near the Fermi energy consist
predominantly of the three $t_{2g}$-orbital components and the hybridization
with oxygen $2p$ orbitals is small. The $d_{yz}$ and $d_{zx}$ orbitals are
exactly degenerate and are lifted from the $d_{xy}$ orbital. The calculated
band dispersion and Fermi surface indicate that the system is not purely
one-dimensional but the coupling between the VO double chains is important.
Comparison with available experimental data suggests the importance of electron
correlations in this system.


title: Finite Lattice-Size Effects in MIMO Detection

abstract:
  Many powerful data detection algorithms employed in multiple-input
multiple-output (MIMO) communication systems, such as sphere decoding (SD) and
lattice-reduction (LR)-aided detection, were initially designed for infinite
lattices. Detection in MIMO systems is, however, based on finite lattices. In
this paper, we systematically study the consequences of finite lattice-size for
the performance and complexity of MIMO detection algorithms formulated for
infinite lattices. Specifically, we find, considering performance and
complexity, that LR does not seem to offer advantages when used in conjunction
with SD.


title: The VLBI morphology of M81* at 43 GHz

abstract:
  The radio source M81* at the core of the nearby spiral galaxy M81 is a
low-luminosity active galactic nucleus. The close distance of 3.63Mpc allows
its morphology to be studied in great detail. Here we present preliminary
results from continuum 7 mm VLBI observations of its core, using
phase-referencing techniques. These observations set constrains on the size of
M81* at this frequency and enable us to test the frequency dependence on its
physical properties.


title: Enlargements of positive sets

abstract:
  In this paper we introduce the notion of enlargement of a positive set in SSD
spaces. To a maximally positive set $A$ we associate a family of enlargements
$\E(A)$ and characterize the smallest and biggest element in this family with
respect to the inclusion relation. We also emphasize the existence of a
bijection between the subfamily of closed enlargements of $\E(A)$ and the
family of so-called representative functions of $A$. We show that the extremal
elements of the latter family are two functions recently introduced and studied
by Stephen Simons. In this way we extend to SSD spaces some former results
given for monotone and maximally monotone sets in Banach spaces.


title: An exact spin liquid state on the kagome lattice with topological order

abstract:
  We find an exact spin liquid state without time reversal symmetry on the
kagome lattice with odd number of electrons per unit cell and explicit wave
functions for all eigenstates. We also obtain that all spin-spin correlations
are zero except trivial cases. We then show that there are anyonic excitations
in our model. Finally, we demonstrate the existence of ground state degeneracy
and gapless edge states indicating nontrivial topological order in our model.
We also label all eiginstates on torus by local and global string operators.


title: A discrete Faa di Bruno's formula

abstract:
  We derive some formulas that rule the behaviour of finite differences under
composition of functions with vector values and arguments.


title: Heavy-Mass Behavior of Ordered Perovskites ACu3Ru4O12 (A = Na, Ca, La)

abstract:
  We synthesized ACu3Ru4O12 (A = Na, Na0.5Ca0.5, Ca, Ca0.5La0.5, La) and
measured their DC magnetization, AC susceptibility, specific heat, and
resistivity, in order to investigate the effects of the hetero-valent
substitution. A broad peak in the DC magnetization around 200 K was observed
only in CaCu3Ru4O12, suggesting the Kondo effect due to localized Cu2+ ions.
However, the electronic specific heat coefficients exhibit large values not
only for CaCu3Ru4O12 but also for all the other samples. Moreover, the Wilson
ratio and the Kadowaki-Woods ratio of our samples are all similar to the values
of other heavy-fermion compounds. These results question the Kondo effect as
the dominant origin of the mass enhancement, and rather indicate the importance
of correlations among itinerant Ru electrons.


title: The Megamaser Cosmology Project: I. VLBI observations of UGC 3789

abstract:
  The Megamaser Cosmology Project (MCP) seeks to measure the Hubble Constant
(Ho) in order to improve the extragalactic distance scale and constrain the
nature of dark energy. We are searching for sources of water maser emission
from AGN with sub-pc accretion disks, as in NGC 4258, and following up these
discoveries with Very Long Baseline Interferometric (VLBI) imaging and spectral
monitoring. Here we present a VLBI map of the water masers toward UGC 3789, a
galaxy well into the Hubble Flow. We have observed masers moving at rotational
speeds up to 800 km/s at radii as small as 0.08 pc. Our map reveals masers in a
nearly edge-on disk in Keplerian rotation about a 10^7 Msun supermassive black
hole. When combined with centripetal accelerations, obtained by observing
spectral drifts of maser features (to be presented in Paper II), the UGC 3789
masers may provide an accurate determination of Ho, independent of luminosities
and metallicity and extinction corrections.


title:
Dynamic Indexability: The Query-Update Tradeoff for One-Dimensional
  Range Queries

abstract:
  The B-tree is a fundamental secondary index structure that is widely used for
answering one-dimensional range reporting queries. Given a set of $N$ keys, a
range query can be answered in $O(\log_B \nm + \frac{K}{B})$ I/Os, where $B$ is
the disk block size, $K$ the output size, and $M$ the size of the main memory
buffer. When keys are inserted or deleted, the B-tree is updated in $O(\log_B
N)$ I/Os, if we require the resulting changes to be committed to disk right
away. Otherwise, the memory buffer can be used to buffer the recent updates,
and changes can be written to disk in batches, which significantly lowers the
amortized update cost. A systematic way of batching up updates is to use the
logarithmic method, combined with fractional cascading, resulting in a dynamic
B-tree that supports insertions in $O(\frac{1}{B}\log\nm)$ I/Os and queries in
$O(\log\nm + \frac{K}{B})$ I/Os. Such bounds have also been matched by several
known dynamic B-tree variants in the database literature.
  In this paper, we prove that for any dynamic one-dimensional range query
index structure with query cost $O(q+\frac{K}{B})$ and amortized insertion cost
$O(u/B)$, the tradeoff $q\cdot \log(u/q) = \Omega(\log B)$ must hold if
$q=O(\log B)$. For most reasonable values of the parameters, we have $\nm =
B^{O(1)}$, in which case our query-insertion tradeoff implies that the bounds
mentioned above are already optimal. Our lower bounds hold in a dynamic version
of the {\em indexability model}, which is of independent interests.


title: Gluonic vacuum, q-theory, and the cosmological constant

abstract:
  In previous work, q-theory was introduced to describe the gravitating
macroscopic behavior of a conserved microscopic variable q. In this article,
the gluon condensate of quantum chromodynamics is considered in terms of
q-theory. The remnant vacuum energy density (i.e., cosmological constant) of an
expanding universe is estimated as K_{QCD}^3 / E_{Planck}^2, with string
tension K_{QCD} \approx (10^2 MeV)^2 and gravitational scale E_{Planck} \approx
10^{19} GeV. The only input for this estimate is general relativity, quantum
chromodynamics, and the Hubble expansion of the present Universe.


title:
Modelling the human pharyngeal airway: validation of numerical
  simulations using in vitro experiments

abstract:
  In the presented study, a numerical model which predicts the flow-induced
collapse within the pharyngeal airway is validated using in vitro measurements.
Theoretical simplifications were considered to limit the computation time.
Systematic comparisons between simulations and measurements were performed on
an in vitro replica, which reflects asymmetries of the geometry and of the
tissue properties at the base of the tongue and in pathological conditions
(strong initial obstruction). First, partial obstruction is observed and
predicted. Moreover, the prediction accuracy of the numerical model is of 4.2%
concerning the deformation (mean quadratic error on the constriction area). It
shows the ability of the assumptions and method to predict accurately and
quickly a fluid-structure interaction.


title:
Anti Plagiarism Application with Algorithm Karp-Rabin at Thesis in
  Gunadarma University

abstract:
  Plagiarism that is plagiarizing or composition retrieval, opinion, etcetera
from other people and makes it is likely composition and opinion him-self.
Plagiarism can be considered to be crime because stealing others copyrights.
Like action a student copying some part of writings without valid permission
from the original writer. In education world, plagiarism perpetrator can get
the devil to pay from school/university. Plagiarism perpetrator conceived of
plagiator. This thing is possible unable to be paid attention by the side of
campus because of limitation from some interconnected factors for example
student amounts Gunadarma University reaching thousands and incommensurate to
tester amounts or lecturer the side of campus in charge directs problem thesis.
In this paper, an application have been developed in order to check and look
for 5 type percentage similarity from a thesis with other one at certain part
or chapters. Percentage got that is 0%, under 15%, between 15-50%, up to 50%
and 100%. So it should be expected that the results could be used by thesis
advisor and also thesis examiner from the Student at Gunadarma University.


title:
Magnetic field sensing beyond the standard quantum limit using 10-spin
  NOON states

abstract:
  The concept of entanglement, in which coherent quantum states become
inextricably correlated, has evolved from one of the most startling and
controversial outcomes of quantum mechanics to the enabling principle of
emerging technologies such as quantum computation and quantum sensors. The use
of entangled particles in measurement permits the transcendence of the standard
quantum limit in sensitivity, which scales as N^1/2 for N particles, to the
Heisenberg limit, which scales as N. This approach has been applied to optical
interferometry using entangled photons and spin pairs for the measurement of
magnetic fields and improvements on atomic clocks. Here, we demonstrate
experimentally an 9.4-fold increase in sensitivity to an external magnetic
field of a 10-spin entangled state, compared with an isolated spin, using
nuclear spins in a highly symmetric molecule. This approach scales in a
favourable way compared to systems where qubit loss is prevalent, and paves the
way for enhanced precision in magnetic field sensing


title: Memory erasure in small systems

abstract:
  We consider an overdamped nanoparticle in a driven double-well potential as a
generic model of an erasable one-bit memory. We study in detail the statistics
of the heat dissipated during an erasure process and show that full erasure may
be achieved by dissipating less heat than the Landauer bound. We quantify the
occurrence of such events and propose a single-particle experiment to verify
our predictions. Our results show that Landauer's principle has to be
generalized at the nanoscale to accommodate heat fluctuations.


title:
Does Mesophase Ag4+xPb2O6-z (0 <= x <= 1, 0,5 <= z <= 0,75) Appeal for a
  Point Contact ATc Superconductivity?

abstract:
  Weakly compacted fine particles of Ag4+xPb2O6-z which is iso-structural with
Bystroem-Evers oxide Ag5Pb2O6 exhibit a novel class of physical properties,
which includes an appearance of diamagnetism at t < 78 degrees Celsius, with
corresponding absence of electric resistance, both events sounding for possible
superconductivity. Weak compaction was performed by controlled pressing of
introductory components Ag2O and PbO2. Pellets were heated from room
temperature in an evacuated chamber, and solid state reaction proceeded at
340-350 degrees Celsius in an oxygen atmosphere released by reaction itself (60
< p < 100 mbar). Electric and magnetic properties appealing for an ambient
temperature superconductivity may be attributed to scattering processes
indicated by tunnelling of Ag-Ag clusters between states localized on the point
contacts formed between adjacent particles. As compared to the work on the
subject during past two decades, reproducibility of output data is
satisfactory, and their correlations to the input preparation conditions appear
as to be conclusive.


title:
A new triclinic modification of the pyrochlore-type KOs2O6
  superconductor

abstract:
  A new modification of KOs2O6, the representative of a new structural type
(Pearson symbol aP18, a=5.5668(1)A, b=6.4519(2)A, c=7.2356(2)A, space group
P-1, no.2) was synthesized employing high pressure technique. Its structure was
determined by single-crystal X-ray diffraction. The structure can be described
as two OsO6 octahedral chains relating to each other through inversion and
forming big voids with K atoms inside. Quantum chemical calculations were
performed on the novel compound and structurally related cubic compound.
High-pressure X-ray study showed that cubic KOs2O6 phase was stable up to
32.5(2) GPa at room temperature.


title: Soft-Input Soft-Output Sphere Decoding

abstract:
  Soft-input soft-output (SISO) detection algorithms form the basis for
iterative decoding. The associated computational complexity often poses
significant challenges for practical receiver implementations, in particular in
the context of multiple-input multiple-output wireless systems. In this paper,
we present a low-complexity SISO sphere decoder which is based on the single
tree search paradigm, proposed originally for soft-output detection in Studer
et al., IEEE J-SAC, 2008. The algorithm incorporates clipping of the extrinsic
log-likelihood ratios in the tree search, which not only results in significant
complexity savings, but also allows to cover a large performance/complexity
trade-off region by adjusting a single parameter.


title: Nonadiabatic corrections to rovibrational levels of H$_2$

abstract:
  The leading nonadiabatic corrections to rovibrational levels of a diatomic
molecule are expressed in terms of three functions of internuclear distance:
corrections to the adiabatic potential, the effective nuclear mass, and the
effective moment of inertia. The resulting radial Schr\"odinger equation for
nuclear motion is solved numerically yielding accurate nonadiabatic energies
for all rovibrational levels of H$_2$ molecule in excellent agreement with
previous calculations by Wolniewicz.


title:
Kaluza-Klein Dark Matter: Direct Detection vis-a-vis LHC (IDM 2008
  proceeding)

abstract:
  We explore the phenomenology of Kaluza-Klein (KK) dark matter in very general
models with universal extra dimensions (UEDs), emphasizing the complementarity
between high-energy colliders and dark matter direct detection experiments. In
models with relatively small mass splittings between the dark matter candidate
and the rest of the (colored) spectrum, the collider sensitivity is diminished,
but direct detection rates are enhanced. UEDs provide a natural framework for
such mass degeneracies. We consider both 5-dimensional and 6-dimensional
non-minimal UED models, and discuss the detection prospects for various KK dark
matter candidates: the KK photon \gamma_1 (5D) the KK Z-boson Z_1 (5D) and the
spinless KK photon \gamma_H (6D). We combine collider limits such as
electroweak precision data and expected LHC reach, with cosmological
constraints from WMAP and the sensitivity of current or planned direct
detection experiments. Allowing for general mass splittings, we show that
neither colliders, nor direct detection experiments by themselves can explore
all of the relevant KK dark matter parameter space. Nevertheless, they probe
different parameter space regions and the combination of the two types of
constraints can be quite powerful. For example, in the case of \gamma_1 in 5D
UEDs the relevant parameter space will be almost completely covered by the
combined LHC and direct detection sensitivities expected in the near future.


title: Recent progress in transverse-momentum dependent PDFs

abstract:
  We present some recently obtained results on transverse-momentum dependent
parton distribution functions (TMD PDFs), the latter being important
ingredients for the description of semi-inclusive hadronic processes. Special
attention is payed to the renormalization group (RG) properties of these
objects. In particular, their leading-order anomalous dimension is calculated
in the light-cone gauge. It is shown that the RG properties can be used to
reveal, in the most economic way, the general structure of the gauge links
entering the operator definition of TMD PDFs.


title: On the E10/Massive Type IIA Supergravity Correspondence

abstract:
  In this paper we investigate in detail the correspondence between E10 and
Romans' massive deformation of type IIA supergravity. We analyse the dynamics
of a non-linear sigma model for a spinning particle on the coset space
E10/K(E10) and show that it reproduces the dynamics of the bosonic as well as
the fermionic sector of the massive IIA theory, within the standard truncation.
The mass deformation parameter corresponds to a generator of E10 outside the
realm of the generators entering the usual D=11 analysis, and is naturally
included without any deformation of the coset model for E10/K(E10). Our
analysis thus provides a dynamical unification of the massless and massive
versions of type IIA supergravity inside E10. We discuss a number of additional
and general features of relevance in the analysis of any deformed supergravity
in the correspondence to Kac-Moody algebras, including recently studied
deformations where the trombone symmetry is gauged.


title:
Blow up of smooth solutions to the barotropic compressible
  magnetohydrodynamic equations with finite mass and energy

abstract:
  We prove that the smooth solutions to the Cauchy problem for the
three-dimensional compressible barotropic magnetohydrodynamic equations with
conserved total mass and finite total energy lose the initial smoothness within
a finite time. Further, we show that the same result holds for the solution to
the Cauchy problem for the multidimensional compressible Navier-Stokes system.
Moreover, for the solution with a finite momentum of inertia we get the
two-sided estimates of different components of total energy.


title: Principe d'Heisenberg et fonctions positives

abstract:
  Starting from a problem in number theory, the article investigates the
properties of the couples of Fourier transforms on the real line, f and g, real
and even, f >= 0 out of an interval (-a, a) and f(0) < 0, g >= 0 out of an
interval (-b, b) and g(0) < 0 . How small the product ab can be ? There is a
strictly positive lower bound, the exact value is not known. The same problem
is considered in several dimensions (where it is related to number theory, as
the article points out).


title:
On the spectrum of the Thue-Morse quasicrystal and the rarefaction
  phenomenon

abstract:
  The spectrum of a weighted Dirac comb on the Thue-Morse quasicrystal is
investigated, and characterized up to a measure zero set, by means of the
Bombieri-Taylor conjecture, for Bragg peaks, and of another conjecture that we
call Aubry-Godr\`eche-Luck conjecture, for the singular continuous component.
The decomposition of the Fourier transform of the weighted Dirac comb is
obtained in terms of tempered distributions. We show that the asymptotic
arithmetics of the $p$-rarefied sums of the Thue-Morse sequence (Dumont;
Goldstein, Kelly and Speer; Grabner; Drmota and Skalba,...), namely the
fractality of sum-of-digits functions, play a fundamental role in the
description of the singular continous part of the spectrum, combined with some
classical results on Riesz products of Peyri\`ere and M. Queff\'elec. The
dominant scaling of the sequences of approximant measures on a part of the
singular component is controlled by certain inequalities in which are involved
the class number and the regulator of real quadratic fields.


title: Fiber lasers generating radially and azimuthally polarized light

abstract:
  A simple, robust, and efficient method to produce either radially or
azimuthally polarized output beam from a fiber laser is presented. Experimental
results reveal that polarization purity of 90% or better can be obtained.


title: Recent developments in superstatistics

abstract:
  We provide an overview on superstatistical techniques applied to complex
systems with time scale separation. Three examples of recent applications are
dealt with in somewhat more detail: the statistics of small-scale velocity
differences in Lagrangian turbulence experiments, train delay statistics on the
British rail network, and survival statistics of cancer patients once diagnosed
with cancer. These examples correspond to three different universality classes:
Lognormal superstatistics, chi-square superstatistics and inverse chi-square
superstatistics.


title: Revisiting the Core Ontology and Problem in Requirements Engineering

abstract:
  In their seminal paper in the ACM Transactions on Software Engineering and
Methodology, Zave and Jackson established a core ontology for Requirements
Engineering (RE) and used it to formulate the "requirements problem", thereby
defining what it means to successfully complete RE. Given that stakeholders of
the system-to-be communicate the information needed to perform RE, we show that
Zave and Jackson's ontology is incomplete. It does not cover all types of basic
concerns that the stakeholders communicate. These include beliefs, desires,
intentions, and attitudes. In response, we propose a core ontology that covers
these concerns and is grounded in sound conceptual foundations resting on a
foundational ontology. The new core ontology for RE leads to a new formulation
of the requirements problem that extends Zave and Jackson's formulation. We
thereby establish new standards for what minimum information should be
represented in RE languages and new criteria for determining whether RE has
been successfully completed.


title: A simple presentation of the handlebody group of genus 2

abstract:
  Using a similar algorithm to Hatcher-Thurston's algorithm for finding a
presentation of the mapping class group of a surface, Wajnryb succeeded to find
a presentation for the handlebody group. This is long and complicated. In this
note I simplify Wajnryb's presentation for the handlebody group of genus g = 2.


title: Extension of functions with bounded finite differences

abstract:
  We prove that functions defined on a lattice in a finite dimensional torus
with bounded finite differences can be smoothly extended to the whole torus,
and relate the bounds on the extension's derivatives with bounds on the
original function's finite differences.


title:
Hybrid: A Definitional Two-Level Approach to Reasoning with Higher-Order
  Abstract Syntax

abstract:
  Combining higher-order abstract syntax and (co)induction in a logical
framework is well known to be problematic. Previous work described the
implementation of a tool called Hybrid, within Isabelle HOL, which aims to
address many of these difficulties. It allows object logics to be represented
using higher-order abstract syntax, and reasoned about using tactical theorem
proving and principles of (co)induction. In this paper we describe how to use
it in a multi-level reasoning fashion, similar in spirit to other meta-logics
such as Twelf. By explicitly referencing provability in a middle layer called a
specification logic, we solve the problem of reasoning by (co)induction in the
presence of non-stratifiable hypothetical judgments, which allow very elegant
and succinct specifications of object logic inference rules.


title:
A Central Difference Numerical Scheme for Fractional Optimal Control
  Problems

abstract:
  This paper presents a modified numerical scheme for a class of Fractional
Optimal Control Problems (FOCPs) formulated in Agrawal (2004) where a
Fractional Derivative (FD) is defined in the Riemann-Liouville sense. In this
scheme, the entire time domain is divided into several sub-domains, and a
fractional derivative (FDs) at a time node point is approximated using a
modified Gr\"{u}nwald-Letnikov approach. For the first order derivative, the
proposed modified Gr\"{u}nwald-Letnikov definition leads to a central
difference scheme. When the approximations are substituted into the Fractional
Optimal Control (FCO) equations, it leads to a set of algebraic equations which
are solved using a direct numerical technique. Two examples, one time-invariant
and the other time-variant, are considered to study the performance of the
numerical scheme. Results show that 1) as the order of the derivative
approaches an integer value, these formulations lead to solutions for integer
order system, and 2) as the sizes of the sub-domains are reduced, the solutions
converge. It is hoped that the present scheme would lead to stable numerical
methods for fractional differential equations and optimal control problems.


title: Features of elastic scattering at small t at the LHC

abstract:
  The problems linked with the extraction of the basic parameters of the hadron
elastic scattering amplitude at the LHC are explored. It is shown that one
should take into account the saturation regime which will lead to new effects
at the LHC.


title: Quantum Coherence of Relic Neutrinos

abstract:
  We argue that in at least a portion of the history of the universe the relic
background neutrinos are spatially-extended, coherent superpositions of mass
states. We show that an appropriate quantum mechanical treatment affects the
neutrino mass values derived from cosmological data. The coherence scale of
these neutrino flavor wavepackets can be an appreciable fraction of the causal
horizon size, raising the possibility of spacetime curvature-induced
decoherence.


title: Probing the Primordial Power Spectrum with Cluster Number Counts

abstract:
  We investigate how well galaxy cluster number counts can constrain the
primordial power spectrum. Measurements of the primary anisotropies in the
cosmic microwave background (CMB) may be limited, by the presence of
foregrounds from secondary sources, to probing the primordial power spectrum at
wave numbers less than about 0.30 h Mpc^{-1}. We break up the primordial power
spectrum into a number of nodes and interpolate linearly between each node.
This allows us to show that cluster number counts could then extend the
constraints on the form of the primordial power spectrum up to wave numbers of
about 0.45 h Mpc^{-1}. We estimate combinations of constraints from PLANCK and
SPT primary CMB and their respective SZ surveys. We find that their
constraining ability is limited by uncertainties in the mass scaling relations.
We also estimate the constraint from clusters detected from a SNAP like
gravitational lensing survey. As there is an unambiguous and simple
relationship between the filtered shear of the lensing survey and the cluster
mass, it may be possible to obtain much tighter constraints on the primordial
power spectrum in this case.


title:
Making new connections towards cooperation in the prisoner's dilemma
  game

abstract:
  Evolution of cooperation in the prisoner's dilemma game is studied where
initially all players are linked via a regular graph, having four neighbors
each. Simultaneously with the strategy evolution, players are allowed to make
new connections and thus permanently extend their neighborhoods, provided they
have been successful in passing their strategy to the opponents. We show that
this simple coevolutionary rule shifts the survival barrier of cooperators
towards high temptations to defect and results in highly heterogeneous
interaction networks with an exponential fit best characterizing their degree
distributions. In particular, there exist an optimal maximal degree for the
promotion of cooperation, warranting the best exchange of information between
influential players.


title: Effect of helicity and rotation on the free decay of turbulent flows

abstract:
  The self-similar decay of energy in a turbulent flow is studied in direct
numerical simulations with and without rotation. Two initial conditions are
considered: one non-helical (mirror-symmetric), and one with maximal helicity.
The results show that, while in the absence of rotation the energy in the
helical and non-helical cases decays with the same rate, in rotating flows the
helicity content has a major impact on the decay rate. These differences are
associated with differences in the energy and helicity cascades when rotation
is present. Properties of the structures that arise in the flow at late times
in each time are also discussed.


title:
Classifications of linear operators preserving elliptic, positive and
  non-negative polynomials

abstract:
  We characterize all linear operators on finite or infinite-dimensional spaces
of univariate real polynomials preserving the sets of elliptic, positive, and
non-negative polynomials, respectively. This is done by means of Fischer-Fock
dualities, Hankel forms, and convolutions with non-negative measures. We also
establish higher-dimensional analogs of these results. In particular, our
classification theorems solve the questions raised in [9] originating from
entire function theory and the literature pertaining to Hilbert's 17th problem.


title:
Off-Lattice Self-Learning Kinetic Monte Carlo: Application to 2D Cluster
  Diffusion on the fcc(111) Surface

abstract:
  We report developments of the kinetic Monte Carlo (KMC) method with improved
accuracy and increased versatility for the description of atomic diffusivity on
metal surfaces. The on-lattice constraint built into our recently proposed
Self-Learning KMC (SLKMC) [1] is released, leaving atoms free to occupy
Off-Lattice positions to accommodate several processes responsible for
small-cluster diffusion, periphery atom motion and hetero-epitaxial growth. The
technique combines the ideas embedded in the SLKMC method with a new pattern
recognition scheme fitted to an Off-Lattice model in which relative atomic
positions is used to characterize and store configurations. Application of a
combination of the drag and the Repulsive Bias Potential (RBP) methods for
saddle points searches, allows the treatment of concerted cluster, and multiple
and single atom motions on equal footing. This tandem approach has helped
reveal several new atomic mechanisms which contribute to cluster migration. We
present applications of this Off-Lattice SLKMC to the diffusion of 2D islands
of Cu (containing 2 to 30 atoms) on Cu and Ag(111), using interatomic potential
from the Embedded Atom Method. For the hetero system Cu/Ag(111), this technique
has uncovered mechanisms involving concerted motions such as shear, breathing
and commensurate-incommensurate occupancies. Although the technique introduces
complexities in storage and retrieval, it does not introduce noticeable extra
computational cost.


title: How robust is quicksort average complexity?

abstract:
  The paper questions the robustness of average case time complexity of the
fast and popular quicksort algorithm. Among the six standard probability
distributions examined in the paper, only continuous uniform, exponential and
standard normal are supporting it whereas the others are supporting the worst
case complexity measure. To the question -why are we getting the worst case
complexity measure each time the average case measure is discredited? -- one
logical answer is average case complexity under the universal distribution
equals worst case complexity. This answer, which is hard to challenge, however
gives no idea as to which of the standard probability distributions come under
the umbrella of universality. The morale is that average case complexity
measures, in cases where they are different from those in worst case, should be
deemed as robust provided only they get the support from at least the standard
probability distributions, both discrete and continuous. Regretfully, this is
not the case with quicksort.


title: Formation of molecular oxygen in ultracold O + OH reaction

abstract:
  We discuss the formation of molecular oxygen in ultracold collisions between
hydroxyl radicals and atomic oxygen. A time-independent quantum formalism based
on hyperspherical coordinates is employed for the calculations. Elastic,
inelastic and reactive cross sections as well as the vibrational and rotational
populations of the product O2 molecules are reported. A J-shifting
approximation is used to compute the rate coefficients. At temperatures T = 10
- 100 mK for which the OH molecules have been cooled and trapped
experimentally, the elastic and reactive rate coefficients are of comparable
magnitude, while at colder temperatures, T < 1 mK, the formation of molecular
oxygen becomes the dominant pathway. The validity of a classical capture model
to describe cold collisions of OH and O is also discussed. While very good
agreement is found between classical and quantum results at T=0.3 K, at higher
temperatures, the quantum calculations predict a larger rate coefficient than
the classical model, in agreement with experimental data for the O + OH
reaction. The zero-temperature limiting value of the rate coefficient is
predicted to be about 6.10^{-12} cm^3 molecule^{-1} s^{-1}, a value comparable
to that of barrierless alkali-metal atom - dimer systems and about a factor of
five larger than that of the tunneling dominated F + H2 reaction.


title:
Electromagnetic waves in uniaxial crystals: General formalism with an
  application to Bessel beams

abstract:
  We present a mathematical formalism describing the propagation of a
completely general electromagnetic wave in a birefringent medium. Analytic
formulas for the refraction and reflection from a plane interface are obtained.
As a particular example, a Bessel beam impinging at an arbitrary angle is
analyzed in detail. Some numerical results showing the formation and
destruction of optical vortices are presented.


title: A non-solvable Galois extension of $\Q$ ramified at 2 only

abstract:
  In this paper, we show the existence of a non-solvable Galois extension of
$\Q$ which is unramified outside 2. The extension $K$ we construct has degree
$2251731094732800=2^{19}(3\cdot 5\cdot 17\cdot 257)^2$ and has root
discriminant $\delta_K <2^{{47/8}}=58.68...$, and is totally complex.


title: Words with intervening neighbours in infinite Coxeter groups are reduced

abstract:
  Consider a graph with vertex set S. A word in the alphabet S has the
intervening neighbours property if any two occurrences of the same letter are
separated by all its graph neighbours. For a Coxeter graph, words represent
group elements. Speyer recently proved that words with the intervening
neighbours property are irreducible if the group is infinite and irreducible.
We present a new and shorter proof using the root automaton for recognition of
irreducible words.


title: Novel approach to a perfect lens

abstract:
  Within the framework of an exact analytical solution of Maxwell equations in
a space domain, it is shown that optical scheme based on a slab with negative
refractive index ($n=-1$) (Veselago lens or Pendry lens) does not possess
focusing properties in the usual sense . In fact, the energy in such systems
does not go from object to its "image", but from object and its "image" to an
intersection point inside a metamaterial layer, or vice versa. A possibility of
applying this phenomenon to a creation of entangled states of two atoms is
discussed.


title: $R$-polynomials of finite monoids of Lie type

abstract:
  This paper concerns the combinatorics of the orbit Hecke algebra associated
with the orbit of a two sided Weyl group action on the Renner monoid of a
finite monoid of Lie type, $M$. It is shown by Putcha in \cite{Putcha97} that
the Kazhdan-Lusztig involution (\cite{KL79}) can be extended to the orbit Hecke
algebra which enables one to define the $R$-polynomials of the intervals
contained in a given orbit. Using the $R$-polynomials, we calculate the
M\"obius function of the Bruhat-Chevalley ordering on the orbits. Furthermore,
we provide a necessary condition for an interval contained in a given orbit to
be isomorphic to an interval in some Weyl group.


title:
Analytical Blowup Solutions to the Pressureless Navier-Stokes-Poisson
  Equations with Density-dependent Viscosity in R^N

abstract:
  We study the N-dimensional pressureless Navier--Stokes-Poisson equations with
density-dependent viscosity. With the extension of the blowup solutions for the
Euler-Poisson equations, the analytical blowup solutions,in radial symmetry, in
R^N are constructed.


title:
Symmetry-break, mixing, instability, and low frequency variability in a
  minimal Lorenz-like system

abstract:
  Starting from the classical Saltzman 2D convection equations, we derive via a
severe spectral truncation a minimal 10 ODE system which includes the thermal
effect of viscous dissipation. Neglecting this process leads to a dynamical
system which includes a decoupled (generalized) Lorenz system. The
consideration of this process breaks an important symmetry, couples the
dynamics of fast and slow variables, ensuing modifications of the structural
properties of the attractor and of the spectral features. When the relevant
nondimensional number (Eckert number Ec) is different from zero, the system is
ergodic and hyperbolic, the slow variables feature long term memory with 1/f
3/2 power spectra, and the fast variables feature amplitude modulation on time
scale of 1/Ec. Increasing the strength of the thermal-viscous feedback has a
stabilizing effect, as both the metric entropy and the Kaplan-Yorke attractor
dimension decrease monotonically with Ec. The analyzed system features very
rich dynamics: it overcomes some of the limitations of the Lorenz system and
might have prototypical value in relevant processes in complex systems
dynamics, such as the interaction between slow and fast variables. the presence
of long term memory and the associated extreme value statistics. Analysis shows
how, neglecting the coupling of slow and fast variables only on the basis of
scale analysis can be catastrophic. In fact, this leads to spurious invariances
that affect essential dynamical properties (ergodicity, hyperbolicity) and that
cause the model losing ability in describing intrinsically multiscale
processes.

categories: nlin.CD cond-mat.stat-mech math.DS physics.flu-dyn


title: Phase conversion in a weakly first-order quark-hadron transition

abstract:
  We investigate the process of phase conversion in a thermally-driven {\it
weakly} first-order quark-hadron transition. This scenario is physically
appealing even if the nature of this transition in equilibrium proves to be a
smooth crossover for vanishing baryonic chemical potential. We construct an
effective potential by combining the equation of state obtained within Lattice
QCD for the partonic sector with that of a gas of resonances in the hadronic
phase, and present numerical results on bubble profiles, nucleation rates and
time evolution, including the effects from reheating on the dynamics for
different expansion scenarios. Our findings confirm the standard picture of a
cosmological first-order transition, in which the process of phase conversion
is entirely dominated by nucleation, also in the case of a weakly first-order
transition. On the other hand, we show that, even for expansion rates much
lower than those expected in high-energy heavy ion collisions, nucleation is
very unlikely, indicating that the main mechanism of phase conversion is
spinodal decomposition. Our results are compared to those obtained for a
strongly first-order transition, as the one provided by the MIT bag model.


title: A geometric approach to time evolution operators of Lie quantum systems

abstract:
  Lie systems in Quantum Mechanics are studied from a geometric point of view.
In particular, we develop methods to obtain time evolution operators of
time-dependent Schrodinger equations of Lie type and we show how these methods
explain certain ad hoc methods used in previous papers in order to obtain exact
solutions. Finally, several instances of time-dependent quadratic Hamiltonian
are solved.


title:
Randomized benchmarking and process tomography for gate errors in a
  solid-state qubit

abstract:
  We present measurements of single-qubit gate errors for a superconducting
qubit. Results from quantum process tomography and randomized benchmarking are
compared with gate errors obtained from a double pi pulse experiment.
Randomized benchmarking reveals a minimum average gate error of 1.1+/-0.3% and
a simple exponential dependence of fidelity on the number of gates. It shows
that the limits on gate fidelity are primarily imposed by qubit decoherence, in
agreement with theory.


title: Gamma-ray luminosity function of Gamma-ray bright AGNs

abstract:
  Detection of Gamma-ray emission from a class of active galactic nuclei (viz
blazars), has been one of the important findings from the Compton Gamma Ray
Observatory (CGRO). However, their Gamma-ray luminosity function has not been
well determined. Few attempts have been made in earlier works, where BL Lacs
and Flat Spectrum Radio Quasars (FSRQs) have been considered as a single source
class. In this paper we investigated the evolution and Gamma-ray luminosity
function of FSRQs and BL Lacs separately. Our investigation indicates no
evolution for BL Lacs, however FSRQs show significant evolution. Pure
luminosity evolution is assumed for FSRQs and exponential and power law
evolution models are examined. Due to the small number of sources, the low
luminosity end index of the luminosity function for FSRQs is constrained with
upper limit. BL Lac luminosity function shows no signature of break. As a
consistency check, the model source distributions deriving from these
luminosity functions show no significant departure from the observed source
distributions.


title:
Kinematics of the Young Stellar Objects associated with the Cometary
  Globules in the Gum Nebula

abstract:
  An analysis of proper motion measurements of the Young Stellar Objects (YSOs)
associated with the Cometary Globules (CGs) in the Gum Nebula is presented.
While earlier studies based on the radial velocity measurements of the CGs
suggested expansion of the system of the CGs, the observed proper motion of the
YSOs shows no evidence for expansion. In particular the kinematics of two YSOs
embedded in CGs is inconsistent with the supernova explosion of the companion
of $\zeta$ Pup about 1.5 Myr ago as the cause of the expansion of the CG
system. YSOs associated with the CGs share the average proper motion of the
member stars of the Vela OB2 association. A few YSOs that have relatively large
proper motions are found to show relatively low infrared excesses.


title:
Quantifying galactic clustering and departures from randomness of the
  inter-galactic void probability function using information geometry

abstract:
  A number of recent studies have estimated the inter-galactic void probability
function and investigated its departure from various random models. We study a
family of parametric statistical models based on gamma distributions, which do
give realistic descriptions for other stochastic porous media. Gamma
distributions contain as a special case the exponential distributions, which
correspond to the `random' void size probability arising from Poisson
processes. The random case corresponds to the information-theoretic maximum
entropy or maximum uncertainty model. Lower entropy models correspond on the
one hand to more `clustered' structures or `more dispersed' structures than
expected at random. The space of parameters is a surface with a natural
Riemannian structure, the Fisher information metric. This surface contains the
Poisson processes as an isometric embedding and provides the geometric setting
for quantifying departures from randomness and perhaps on which may be written
evolutionary dynamics for the void size distribution. Estimates are obtained
for the two parameters of the void diameter distribution for an illustrative
example of data published by Fairall.


title:
Cross-Layer Link Adaptation Design for Relay Channels with Cooperative
  ARQ Protocol

abstract:
  The cooperative automatic repeat request (C-ARQ) is a link layer relaying
protocol which exploits the spatial diversity and allows the relay node to
retransmit the source data packet to the destination, when the latter is unable
to decode the source data correctly. This paper presents a cross-layer link
adaptation design for C-ARQ based relay channels in which both source and relay
nodes employ adaptive modulation coding and power adaptation at the physical
layer. For this scenario, we first derive closed-form expressions for the
system spectral efficiency and average power consumption. We then present a low
complexity iterative algorithm to find the optimized adaptation solution by
maximizing the spectral efficiency subject to a packet loss rate (PLR) and an
average power consumption constraint. The results indicate that the proposed
adaptation scheme enhances the spectral efficiency noticeably when compared to
other adaptive schemes, while guaranteeing the required PLR performance.


title: Ground-state energy shift of n pions and m kaons in a finite volume

abstract:
  The ground state energy of a collection of n pions and m kaons with short
range interactions is calculated for a volume with finite spatial extent L and
periodic boundary conditions. This calculation is accomplished to order L^-6 in
the large volume expansion. With this result one can extract the various two-
and three-body interactions between pions and kaons from lattice QCD data.


title: CFT Duals for Extreme Black Holes

abstract:
  It is argued that the general four-dimensional extremal Kerr-Newman-AdS-dS
black hole is holographically dual to a (chiral half of a) two-dimensional CFT,
generalizing an argument given recently for the special case of extremal Kerr.
Specifically, the asymptotic symmetries of the near-horizon region of the
general extremal black hole are shown to be generated by a Virasoro algebra.
Semiclassical formulae are derived for the central charge and temperature of
the dual CFT as functions of the cosmological constant, Newton's constant and
the black hole charges and spin. We then show, assuming the Cardy formula, that
the microscopic entropy of the dual CFT precisely reproduces the macroscopic
Bekenstein-Hawking area law. This CFT description becomes singular in the
extreme Reissner-Nordstrom limit where the black hole has no spin. At this
point a second dual CFT description is proposed in which the global part of the
U(1) gauge symmetry is promoted to a Virasoro algebra. This second description
is also found to reproduce the area law. Various further generalizations
including higher dimensions are discussed.


title: An Intrinsic Approach to Forces in Magnetoelectric Media

abstract:
  This paper offers a conceptually straightforward method for the calculation
of stresses in polarisable media based on the notion of a drive form and its
property of being closed in spacetimes with symmetry. After an outline of the
notation required to exploit the powerful exterior calculus of differential
forms, a discussion of the relation between Killing isometries and conservation
laws for smooth and distributional drive forms is given. Instantaneous forces
on isolated spacetime domains and regions with interfaces are defined, based on
manifestly covariant equations of motion. The remaining sections apply these
notions to media that sustain electromagnetic stresses, with emphasis on
homogeneous magnetoelectric material. An explicit calculation of the average
pressure exerted by a monochromatic wave normally incident on a homogeneous,
magnetoelectric slab in vacuo is presented and the concluding section
summarizes how this pressure depends on the parameters in the magnetoelectric
tensors for the medium.


title: List Decoding Tensor Products and Interleaved Codes

abstract:
  We design the first efficient algorithms and prove new combinatorial bounds
for list decoding tensor products of codes and interleaved codes. We show that
for {\em every} code, the ratio of its list decoding radius to its minimum
distance stays unchanged under the tensor product operation (rather than
squaring, as one might expect). This gives the first efficient list decoders
and new combinatorial bounds for some natural codes including multivariate
polynomials where the degree in each variable is bounded. We show that for {\em
every} code, its list decoding radius remains unchanged under $m$-wise
interleaving for an integer $m$. This generalizes a recent result of Dinur et
al \cite{DGKS}, who proved such a result for interleaved Hadamard codes
(equivalently, linear transformations). Using the notion of generalized Hamming
weights, we give better list size bounds for {\em both} tensoring and
interleaving of binary linear codes. By analyzing the weight distribution of
these codes, we reduce the task of bounding the list size to bounding the
number of close-by low-rank codewords. For decoding linear transformations,
using rank-reduction together with other ideas, we obtain list size bounds that
are tight over small fields.


title: A tight-binding approach to uniaxial strain in graphene

abstract:
  We analyze the effect of tensional strain in the electronic structure of
graphene. In the absence of electron-electron interactions, within linear
elasticity theory, and a tight-binding approach, we observe that strain can
generate a bulk spectral gap. However this gap is critical, requiring threshold
deformations in excess of 20%, and only along preferred directions with respect
to the underlying lattice. The gapless Dirac spectrum is robust for small and
moderate deformations, and the gap appears as a consequence of the merging of
the two inequivalent Dirac points, only under considerable deformations of the
lattice. We discuss how strain-induced anisotropy and local deformations can be
used as a means to affect transport characteristics and pinch off current flow
in graphene devices.


title:
Joint Adaptive Modulation-Coding and Cooperative ARQ for Wireless Relay
  Networks

abstract:
  This paper presents a cross-layer approach to jointly design adaptive
modulation and coding (AMC) at the physical layer and cooperative truncated
automatic repeat request (ARQ) protocol at the data link layer. We first derive
an exact closed form expression for the spectral efficiency of the proposed
joint AMC-cooperative ARQ scheme. Aiming at maximizing this system performance
measure, we then optimize an AMC scheme which directly satisfies a prescribed
packet loss rate constraint at the data-link layer. The results indicate that
utilizing cooperative ARQ as a retransmission strategy, noticeably enhances the
spectral efficiency compared with the system that employs AMC alone at the
physical layer. Moreover, the proposed adaptive rate cooperative ARQ scheme
outperforms the fixed rate counterpart when the transmission modes at the
source and relay are chosen based on the channel statistics. This in turn
quantifies the possible gain achieved by joint design of AMC and ARQ in
wireless relay networks.


title: Problems and paradoxes of the Lifshitz theory

abstract:
  The problems and paradoxes of the Lifshitz theory in application to real
dielectric and semiconductor materials are reviewed. It is shown that the
inclusion of drift current of conduction electrons into the model of dielectric
response results in contradictions with both thermodynamics and experimental
data of different experimental groups. Physical reasons why the problems and
paradoxes arise are analyzed and found to be connected with the violation of
basic applicability condition of the Lifshitz theory, the thermal equilibrium.
A recent alternative approach to the resolution of the problems based on the
inclusion of screening effects and diffusion current is considered and
demonstrated to be thermodynamically and experimentally inconsistent. It is
argued that the inclusion of the diffusion current leads to an even deeper
violation of thermal equilibrium. Phenomenologically, the Lifshitz theory with
role of drift and diffusion currents neglected is shown to be free of problems
and in agreement with both thermodynamics and all available experimental data.


title:
Quantum recoil effects in finite-time disentanglement of two
  distinguishable atoms

abstract:
  Starting from the requirement of distinguishability of two atoms by their
positions, it is shown that photon recoil has a strong influence on finite-time
disentanglement and in some cases prevents its appearance. At near-field inter
atomic distances well localized atoms, with maximally one atom being initially
excited, may suffer disentanglement at a single finite time or even at a series
of equidistant finite times, depending on their mean inter atomic distance and
their initial electronic preparation.


title: Non-commutative reading of the complex plane through Delone sequences

abstract:
  The Berezin-Klauder-Toeplitz ("anti-Wick") quantization or "non-commutative
reading" of the complex plane, viewed as the phase space of a particle moving
on the line, is derived from the resolution of the unity provided by the
standard (or gaussian) coherent states. The construction properties of these
states and their attractive properties are essentially based on the energy
spectrum of the harmonic oscillator, that is on the natural numbers. This work
is an attempt for following the same path by considering sequences of
non-negative numbers which are not "too far" from the natural numbers. In
particular, we examine the consequences of such perturbations on the
non-commutative reading of the complex plane in terms of its probabilistic,
functional, and localization aspects.


title: What the inflaton might tell us about RHIC/LHC

abstract:
  Topical phenomena in high-energy physics related to collision experiments of
heavy nuclei ("Little Bang") and early universe cosmology ("Big Bang") involve
far-from-equilibrium dynamics described by quantum field theory. One example
concerns the role of plasma instabilities for the process of thermalization in
heavy-ion collisions. The reheating of the early universe after inflation may
exhibit rather similar phenomena following a tachyonic or parametric resonance
instability. Certain universal aspects associated to nonthermal fixed points
even quantitatively agree, and considering these phenomena from a common
perspective can be fruitful.


title:
Acetylene - Argon Plasmas Measured at a Biased Substrate Electrode for
  Diamond-Like Carbon Deposition. Part 1: Mass Spectroscopy

abstract:
  We report, for the first time, quadrupole mass spectrometry of neutral and
positive ionic hydrocarbon species measured at the rf biased substrate
electrode of an inductively coupled plasma for acetylene rich C2H2:Ar mixtures
under various bias, frequency and pressure conditions. It has been observed
that, irrespective of initial gas mixture, the resultant plasma is dominated by
argon neutrals and ions. This is attributed to highly efficient conversion of
acetylene to C2H due to the enhanced electron density compared to a standard
capacitive plasma where the acetylene (neutral and ion) species remain
dominant. This conversion may be crucial to film formation via inert rather
than hydrocarbon ion bombardment. In addition, the transient formation of CH4
from acetylene has been discovered using IR absorption spectroscopy with time
constants similar to observed pressure variations. Rate coefficients and rates
for many of the reaction mechanisms, calculated using measured EEDFs and
species densities, are given. These results have important application in
plasma models and growth studies for hydrogenated amorphous or diamond-like
carbon film deposition. Film growth under similar plasma conditions is reported
in an associated paper along with ion energy distributions for important growth
species.


title:
Joint Adaptive Modulation Coding and Cooperative ARQ over Relay
  Channels-Applications to Land Mobile Satellite Communications

abstract:
  In a cooperative relay network, a relay node (R) facilitates data
transmission to the destination node (D), when the latter is unable to decode
the source node (S) data correctly. This paper considers such a system model
and presents a cross-layer approach to jointly design adaptive modulation and
coding (AMC) at the physical layer and cooperative truncated automatic repeat
request (ARQ) protocol at the data link layer. We first derive a closed form
expression for the spectral efficiency of the joint cooperative ARQ-AMC scheme.
Aiming at maximizing this performance measure, we then optimize two AMC schemes
for S-D and R-D links, which directly satisfy a prescribed packet loss rate
constraint. As an interesting application, we also consider the problem of
joint link adaptation and blockage mitigation in land mobile satellite
communications (LMSC). We also present a new relay-assisted transmission
protocol for LMSC, which delivers the source data to the destination via the
relaying link, when the S-D channel is in outage. Numerical results indicate
that the proposed schemes noticeably enhances the spectral efficiency compared
to a system, which uses a conventional ARQ-AMC scheme at the S-D link, or a
system which employs an optimized fixed rate cooperative-ARQ protocol.


title:
Dipole-active optical phonons in YTiO_3: ellipsometry study and
  lattice-dynamics calculations

abstract:
  The anisotropic complex dielectric response was accurately extracted from
spectroscopic ellipsometry measurements at phonon frequencies for the three
principal crystallographic directions of an orthorhombic (Pbnm) YTiO_3 single
crystal. We identify all twenty five infrared-active phonon modes allowed by
symmetry, 7B_1u, 9B_2u, and 9B_3u, polarized along the c-, b-, and a-axis,
respectively. From a classical dispersion analysis of the complex dielectric
functions \tilde\epsilon(\omega) and their inverses -1/\tilde\epsilon(\omega)
we define the resonant frequencies, widths, and oscillator strengths of the
transverse (TO) and longitudinal (LO) phonon modes. We calculate
eigenfrequencies and eigenvectors of B_1u, B_2u, and B_3u normal modes and
suggest assignments of the TO phonon modes observed in our ellipsometry spectra
by comparing their frequencies and oscillator strengths with those resulting
from the present lattice-dynamics study. Based on these assignments, we
estimate dynamical effective charges of the atoms in the YTiO_3 lattice. We
find that, in general, the dynamical effective charges in YTiO_3 lattice are
typical for a family of perovskite oxides. By contrast to a ferroelectric
BaTiO_3, the dynamical effective charge of oxygen related to a displacement
along the c-axis does not show the anomalously large value. At the same time,
the dynamical effective charges of Y and ab-plane oxygen exhibit anisotropy,
indicating strong hybridization along the a-axis.


title: Bogolyubov-Hartree-Fock approach to studying the QCD ground state

abstract:
  The quark's behaviour while influenced by a strong stochastic gluon field is
analyzed. An approximate procedure for calculating the effective Hamiltonian is
developed and the corresponding ground state within the Hartree-Fock-Bogolyubov
approach is found. The comparative analysis of various Hamiltonian models is
given and transition to the chiral limit in the Keldysh model is discussed in
detail.


title:
Electrodynamics at non-zero temperature, chemical potential, and Bose
  condensate

abstract:
  Electrodynamics of charged scalar bosons and spin 1/2 fermions is studied at
non-zero temperature, chemical potentials, and possible Bose condensate of the
charged scalars. Debye screening length, plasma frequency, and the photon
dispersion relation are calculated. It is found that in presence of the
condensate the time-time component of the photon polarization operator in the
first order in electric charge squared acquires infrared singular parts
proportional to inverse powers of the spatial photon momentum k.


title:
Acetylene - Argon Plasmas Measured at a Biased Substrate Electrode for
  Diamond-Like Carbon Deposition. Part 2: Ion Energy Distributions

abstract:
  Ion energy distributions have been determined at the rf-bias electrode in an
inductively-coupled acetylene-argon plasma for various substrate bias voltages
and frequencies under conditions suitable for film deposition. These are
compared with those obtained at the grounded wall of a capacitively coupled
plasma. In the former, for pressures up to 25 mTorr, the IEDs exhibit bimodal
structures with peak separation values that follow the expected dependence on
voltage and frequency. At higher pressures, 120 mTorr, the bimodal structure is
replaced by a single peak. For all conditions, the dominant ion is Ar+ or ArH+
despite a set C2H2:Ar flow ratio of 2:1, and this can be attributed to the high
electron dissociation of the parent molecule. Diamond-like carbon films
indicate a peak hardness at an ion energy of around 90 eV and a very sharp fall
in hardness is noted beyond this value. This is similar to the observed
bombardment energy relationship for sp3 bond formation in hydrogen-free
tetragonal amorphous carbon or bias-sputtered films. However, due to the lack
of carbon-based ions, an alternative film growth mechanism must be considered,
possibly based on argon knock-on implantation of surface adsorbed carbon
species. The results have shown that the use of high frequency bias or bias
harmonics may lead to much narrower ion energy distributions.


title: Center vortex influence on the Dirac spectrum

abstract:
  We study the influence of center vortices on the low-lying eigenmodes of the
Dirac operator, in both the overlap and asqtad formulations. For
center-projected configurations, one finds that the low-lying near-zero modes
are present in the staggered (asqtad) formulation, but not in the overlap and
"chirally-improved" formulations. We argue that this is due to the absence of a
field-independent chiral symmetry in the latter formulations, when the Dirac
operator is evaluated on the very rough configurations generated by center
projection. We also confirm and extend the results of Kovalenko et al. [Phys.
Lett. B 648, 383 (2007)], finding strong correlations between center vortex
locations, and the scalar density of low-lying Dirac eigenmodes on unprojected
lattices, in both asqtad and overlap formulations. It is found that the
low-lying eigenmodes have their largest concentrations in point-like regions,
rather than on submanifolds of higher dimensionality.


title: Dirac Gauginos in General Gauge Mediation

abstract:
  We extend the formulation by Meade, Seiberg and Shih of general gauge
mediation of supersymmetry breaking to include Dirac masses for the gauginos.
These appear through mixing of the visible sector gauginos with additional
states in adjoint representations. We illustrate the method by reproducing the
existing results in the literature for the gaugino and sfermion masses when
preserving R-symmetry. We then explain how the generation of same sign masses
for the two propagating degrees of freedom in the adjoint scalars can be
achieved. We end by commenting on the use of the formalism for describing U(1)
mixing.


title:
Acceleration statistics of finite-sized particles in turbulent flow: the
  role of Faxen forces

abstract:
  The dynamics of particles in turbulence when the particle-size is larger than
the dissipative scale of the carrier flow is studied. Recent experiments have
highlighted signatures of particles finiteness on their statistical properties,
namely a decrease of their acceleration variance, an increase of correlation
times -at increasing the particles size- and an independence of the probability
density function of the acceleration once normalized to their variance. These
effects are not captured by point particle models. By means of a detailed
comparison between numerical simulations and experimental data, we show that a
more accurate model is obtained once Faxen corrections are included.


title:
Manipulating the Loss in Electromagnetic Cloaks for Perfect Wave
  Absorption

abstract:
  We examine several ways to manipulate the loss in electromagnetic cloaks,
based on transformation electromagnetics. It is found that, by utilizing
inherent electric and magnetic losses of metamaterials, perfect wave absorption
can be achieved based on several popular designs of electromagnetic cloaks. A
practical implementation of the absorber, consisting of ten discrete layers of
metamaterials, is proposed. The new devices demonstrate super-absorptivity over
a moderate wideband range, suitable for both microwave and optical
applications. It is corroborated that the device is functional with a
subwavelength thickness and, hence, advantageous compared to the conventional
absorbers.


title: Two and one-dimensional honeycomb structures of silicon and germanium

abstract:
  Based on first-principles calculations of structure optimization, phonon
modes and finite temperature molecular dynamics, we predict that silicon and
germanium have stable, two-dimensional, low-buckled, honeycomb structures.
Similar to graphene, they are ambipolar and their charge carriers can behave
like a massless Dirac fermions due to their pi- and pi*-bands which are crossed
linearly at the Fermi level. In addition to these fundamental properties, bare
and hydrogen passivated nanoribbons of Si and Ge show remarkable electronic and
magnetic properties, which are size and orientation dependent. These properties
offer interesting alternatives for the engineering of diverse nanodevices.


title: A Spectral Algorithm for Learning Hidden Markov Models

abstract:
  Hidden Markov Models (HMMs) are one of the most fundamental and widely used
statistical tools for modeling discrete time series. In general, learning HMMs
from data is computationally hard (under cryptographic assumptions), and
practitioners typically resort to search heuristics which suffer from the usual
local optima issues. We prove that under a natural separation condition (bounds
on the smallest singular value of the HMM parameters), there is an efficient
and provably correct algorithm for learning HMMs. The sample complexity of the
algorithm does not explicitly depend on the number of distinct (discrete)
observations---it implicitly depends on this quantity through spectral
properties of the underlying HMM. This makes the algorithm particularly
applicable to settings with a large number of observations, such as those in
natural language processing where the space of observation is sometimes the
words in a language. The algorithm is also simple, employing only a singular
value decomposition and matrix multiplications.


title: Spin-Transport in Defective Graphene Nanoribbons

abstract:
  Using first-principles calculations, the effect of magnetic point defects
(vacancy and adatom) is investigated in zigzag graphene nanoribbons. The
structural, electronic, and spin-transport properties are studied. While
pristine ribbons display anti-parallel spin states at their edges, the defects
are found to perturb this coupling. The introduction of a vacancy drastically
reduces the energy difference between parallel and anti-parallel spin
orientations, though the latter is still favored. Moreover, the local magnetic
moment of the defect is screened by the edges so that the total magnetic moment
is quite small. In contrast, when an adatom is introduced, the parallel spin
orientation is preferred and the local magnetic moment of the defect adds up to
the contributions of the edges. Furthermore, a spin-polarized transmission is
observed at the Fermi energy, suggesting the use of such a defective graphene
nanoribbon as spin-valve device.


title: Exactly solved models of polyominoes and polygons

abstract:
  This chapter deals with the exact enumeration of certain classes of
self-avoiding polygons and polyominoes on the square lattice. We present three
general approaches that apply to many classes of polyominoes. The common
principle to all of them is a recursive description of the polyominoes which
then translates into a functional equation satisfied by the generating
function. The first approach applies to classes of polyominoes having a linear
recursive structure and results in a rational generating function. The second
approach applies to classes of polyominoes having an algebraic recursive
structure and results in an algebraic generating function. The third approach,
commonly called the Temperley method, is based on the action of adding a new
column to the polyominoes. We conclude by discussing some open questions.


title: Reformulation Instead of Renormalizations

abstract:
  In this article I show why the fundamental constants obtain perturbative
corrections in higher orders, why the renormalizations work and how to
reformulate the theory in order to avoid these technical and conceptual
complications. I demonstrate that the perturbative mass and charge corrections
are caused exclusively with the kinetic nature of the interaction Lagrangian.
As soon as it is not purely quantum mechanical (or QFT) specific feature, the
problem can be demonstrated on a classical two-body problem. The latter can be
solved in different ways, one of them being correct and good for applying the
perturbation theory (if necessary) and another one being tricky and awkward.
The first one is physically and technically natural - it is a
center-of-inertia-and-relative-variable formulation. The second one - mixed
variable formulation - is unnecessarily complicated and leads to the mass and
charge corrections even in the Newtonian mechanics of two bound bodies. The
perturbation theory in QFT is factually formulated in the mixed variables -
that is why it brings corrections to the fundamental constants. This
understanding opens a way of correctly formulating the QFT equations and thus
to simplify the QFT calculations technically and conceptually. For example, in
scattering problems in QED it means accounting exactly the quantized
electromagnetic field influence in the free in and out states of charged
particles so no infrared and ultraviolet problems arise. In bound states it
means obtaining the energy corrections (the Lamb shift, the anomalous magnetic
moment) quite straightforwardly and without renormalizations.


title:
The role of f -electrons in the Fermi surface of the heavy fermion
  superconductor beta-YbAlB4

abstract:
  We present a detailed quantum oscillation study of the Fermi surface of the
recently discovered Yb-based heavy fermion superconductor beta-YbAlB4 . We
compare the data, obtained at fields from 10 to 45 Tesla, to band structure
calculations performed using the local density approximation. Analysis of the
data suggests that f-holes participate in the Fermi surface up to the highest
magnetic fields studied. We comment on the significance of these findings for
the unconventional superconducting properties of this material.


title:
Magnetic order in CaFe1-xCoxAsF (x = 0, 0.06, 0.12) superconductor
  compounds

abstract:
  A Neutron Powder Diffraction (NPD) experiment has been performed to
investigate the structural phase transition and magnetic order in CaFe1-xCoxAsF
superconductor compounds (x = 0, 0.06, 0.12). The parent compound CaFeAsF
undergoes a tetragonal to orthorhombic phase transition at 134(3) K, while the
magnetic order in form of a spin-density wave (SDW) sets in at 114(3) K. The
antiferromagnetic structure of the parent compound has been determined with a
unique propagation vector k = (1,0,1) and the Fe saturation moment of 0.49(5)uB
aligned along the long a-axis. With increasing Co doping, the long range
antiferromagnetic order has been observed to coexist with superconductivity in
the orthorhombic phase of the underdoped CaFe0.94Co0.06AsF with a reduced Fe
moment (0.15(5)uB). Magnetic order is completely suppressed in optimally doped
CaFe0.88Co0.12AsF. We argue that the coexistence of SDW and superconductivity
might be related to mesoscopic phase separation.


title:
Subdiffraction and spatial filtering due to periodic spatial modulation
  of the gain/loss profile

abstract:
  We investigate light propagation through materials with periodically
modulated gain/loss profile in both transverse and longitudinal directions,
i.e. in material with two-dimensional modulation in space. We predict effects
of self-collimation (diffraction-free propagation) of the beams, as well as
superdiffusion (spatial frequency filtering) of the beams in depending on the
geometry of the gain/loss lattice, and justify the predictions by numerical
simulations of the paraxial wave propagation equations.


title: Notes on Algebraic Cycles and Homotopy theory

abstract:
  We show that a conjecture by Lawson holds, that is, the inclusion from the
Chow variety $C_{p,d}(P^n)$ of all effective algebraic p-cycles of degree d in
n-dimensional projective space to the space of effective algebraic p-cycles is
2d-connected. As a result, the homotopy and homology groups of $C_{p,d}(P^n)$
are calculated up to 2d. We also show an analogous statement for Chow variety
$C_{p,d}(\P^n)$ over algebraically closed fields of arbitrary characteristic
and compute their etale homotopy groups up to 2d.


title:
On the possibility of primary identification of individual cosmic ray
  showers

abstract:
  The transition between the Galactic and extragalactic cosmic ray components
could take place either in the region of the spectrum known as the second knee
or in the ankle. There are several models of the transition but it is not
possible to confirm or even rule out any of them from the flux measurement
alone. Therefore, the measurement of the composition as a function of primary
energy will play a fundamental role for the understanding of this phenomenon.
  In this work we study the possibility of primary identification in an event
by event basis in the ankle region, around $E = 10^{18}$ eV. We consider as
case study the enhancements of the Pierre Auger Southern Observatory, which are
under construction in Malague, Province of Mendoza, Argentina. We use a
non-parametric technique to estimate the density functions, from Monte Carlo
data, corresponding to different combination of mass sensitive parameters and
type of primaries. These estimates are used to obtain the classification
probability of protons and iron nuclei for the different combination of
parameters considered. We find that, after considering all relevant
fluctuations, the maximum classification probability obtained combining surface
and fluorescence detectors parameters is of order of 90%.


title:
New Spin(7) holonomy metrics admiting G2 holonomy reductions and
  M-theory/IIA dualities

abstract:
  IAs is well known, when D6 branes wrap a special lagrangian cycle on a non
compact CY 3-fold in such a way that the internal string frame metric is Kahler
there exists a dual description, which is given in terms of a purely
geometrical eleven dimensional background with an internal metric of $G_2$
holonomy. It is also known that when D6 branes wrap a coassociative cycle of a
non compact $G_2$ manifold in presence of a self-dual two form strength the
internal part of the string frame metric is conformal to the $G_2$ metric and
there exists a dual description, which is expressed in terms of a purely
geometrical eleven dimensional background with an internal non compact metric
of Spin(7) holonomy. In the present work it is shown that any $G_2$ metric
participating in the first of these dualities necessarily participates in one
of the second type. Additionally, several explicit Spin(7) holonomy metrics
admitting a $G_2$ holonomy reduction along one isometry are constructed. These
metrics can be described as $R$-fibrations over a 6-dimensional Kahler metric,
thus realizing the pattern Spin(7) $\to G_2\to$ (Kahler) mentioned above.
Several of these examples are further described as fibrations over the
Eguchi-Hanson gravitational instanton and, to the best of our knowledge, have
not been previously considered in the literature.