title:
On the Fundamental Properties of Linear Parameter-Varying Dynamic
  Systems Under Parametrical Multi-Perturbations. Applications to Time-Delay
  Systems. Preliminary Results

abstract:
  This paper deals with a unifying approach to the problems of computing the
admissible sets of parametrical multi perturbations in appropriate bounded sets
such that some fundamental properties of parameter-varying linear dynamic
systems are maintained provided that the so-called (i.e. perturbation-free)
nominal system possesses such properties. The sets of parametrical multi
perturbations include any combinations of parametrical multi perturbations in
the matrix of dynamics as well as in the control, output and input-output
interconnection matrices which belong to some prescribed bounded domain in the
complex space. The various properties which are investigated are
controllability, observability, output controllability and existence of minimal
state-space realizations together with the associate existence or not of
associate decoupling, transmission and invariant zeros. All the matrices of
parameters including the nominal and the disturbed ones which parameterize the
dynamic system may be real or complex. The radii of the multi- parametrical
perturbations are calculated in a simple way. The obtained results are then
applied to systems subject to a finite number of point internal delays and
parametrical multi perturbations by comparing the state- space descriptions of
such systems with the general descriptions previously investigated. In
particular, the contributions of the delays to the spectral descriptions are
assimilated to the contributions of a set of varying parameters in a domain for
the general description.


title:
Effect of cluster size of chalcogenide glass nanocolloidal solutions on
  the surface morphology of spin-coated amorphous films

abstract:
  Amorphous chalcogenide thin film deposition can be achieved by a spin-coating
technique from proper solutions of the corresponding glass. Films produced in
this way exhibit certain grain texture, which is presumably related to the
cluster size in solution. This paper deals with the search of such a
correlation between grain size of surface morphology of as-deposited
spin-coated As33S67 chalcogenide thin films and cluster size of the glass in
butylamine solutions. Optical absorption spectroscopy and dynamic light
scattering were employed to study optical properties and cluster size
distributions in the solutions at various glass concentrations. Atomic force
microscopy is used to study the surface morphology of the surface of
as-deposited and thermally stabilized spin-coated films. Dynamic light
scattering revealed a concentration dependence of cluster size in solution.
Spectral-dependence dynamic light scattering studies showed an interesting
athermal photo-aggregation effect in the liquid state.


title:
Large Deviations for Random Trees and the Branching of RNA Secondary
  Structures

abstract:
  We give a Large Deviation Principle (LDP) with explicit rate function for the
distribution of vertex degrees in plane trees, a combinatorial model of RNA
secondary structures. We calculate the typical degree distributions based on
nearest neighbor free energies, and compare our results with the branching
configurations found in two sets of large RNA secondary structures. We find
substantial agreement overall, with some interesting deviations which merit
further study.


title:
How many distribution functions are there? Bracketing entropy bounds for
  high dimensional distribution functions

abstract:
  This paper has been withdrawn by the authors due to a crucial error in a
bound on page 19 and some other errors earlier in the paper.


title:
On the Asymptotic Expansions for Time-Varying Scalar Differential
  Equations Possesssing Limiting Differential Equations by Application of the
  Residue Theorem to their Discretized Counterparts. Preliminary Results

abstract:
  In this paper, it is proved that, in a dual context, asymptotic expansions of
ordinary linear time-differential equations which possess limiting equations to
their limiting equations might be obtained by first discretizing them and then
using residues calculation for such discrete- time counterparts


title:
On the derivative of the associated Legendre function of the first kind
  of integer degree with respect to its order

abstract:
  The derivative of the associated Legendre function of the first kind of
integer degree with respect to its order, $\partial
P_{n}^{\mu}(z)/\partial\mu$, is studied. After deriving and investigating
general formulas for $\mu$ arbitrary complex, a detailed discussion of
$[\partial P_{n}^{\mu}(z)/\partial\mu]_{\mu=\pm m}$, where $m$ is a
non-negative integer, is carried out. The results are applied to obtain several
explicit expressions for the associated Legendre function of the second kind of
integer degree and order, $Q_{n}^{\pm m}(z)$. In particular, we arrive at
formulas which generalize to the case of $Q_{n}^{\pm m}(z)$ ($0\leqslant
m\leqslant n$) the well-known Christoffel's representation of the Legendre
function of the second kind, $Q_{n}(z)$. The derivatives $[\partial^{2}
P_{n}^{\mu}(z)/\partial\mu^{2}]_{\mu=m}$, $[\partial
Q_{n}^{\mu}(z)/\partial\mu]_{\mu=m}$ and $[\partial
Q_{-n-1}^{\mu}(z)/\partial\mu]_{\mu=m}$, all with $m>n$, are also evaluated.


title:
Complex coacervation: A field theoretic simulation study of
  polyelectrolyte complexation

abstract:
  Using the complex Langevin sampling strategy, field theoretic simulations are
performed to study the equilibrium phase behavior and structure of symmetric
polycation-polyanion mixtures without salt in good solvents. Static structure
factors for the segment density and charge density are calculated and used to
study the role of fluctuations in the electrostatic and chemical potential
fields beyond the random phase approximation. We specifically focus on the role
of charge density and molecular weight on the structure and complexation
behavior of polycation-polyanion solutions. A demixing phase transition to form
a ``complex coacervate'' is observed in strongly charged systems, and the
corresponding spinodal and binodal boundaries of the phase diagram are
investigated.


title: Disentanglement of two harmonic oscillators in relativistic motion

abstract:
  We study the dynamics of quantum entanglement between two Unruh-DeWitt
detectors, one stationary (Alice), and another uniformly accelerating (Rob),
with no direct interaction but coupled to a common quantum field in (3+1)D
Minkowski space. We find that for all cases studied the initial entanglement
between the detectors disappears in a finite time ("sudden death"). After the
moment of total disentanglement the correlations between the two detectors
remain nonzero until late times. The relation between the disentanglement time
and Rob's proper acceleration is observer dependent. The larger the
acceleration is, the longer the disentanglement time in Alice's coordinate, but
the shorter in Rob's coordinate.


title:
Comment on `Evidence for pairing above Tc from the dispersion in the
  pseudogap phase of cuprates' by A. Kanigel et al

abstract:
  In a recent preprint [0803.3052] A. Kanigel et al report evidence for
Bogoliubov-type excitations in the pseudogap phase in the anti-nodal region,
where a robust pseudogap remains well above Tc. This important experimental
result has been theoretically predicted by us almost 6 years ago on a basis of
the phenomenological boson fermion model. An earlier theoretical prediction on
the basis of this model was that of a pseudogap in the electron DOS, setting in
at some temperature T* and evolving into the superconducting gap upon
approaching Tc. A natural logical pursuit of this early work was to show that,
in order to have a superconducting state evolved out of a pseudogap state, the
diamagnetic bosonic pair fluctuations (characterizing the pseudogap phase) have
to be propagating modes, which are phase correlated over finite distances above
Tc. If so, then the pseudogap feature has to be reflected in characteristic
features of the single particle excitations, showing remnants of the Bogoliubov
modes inherent in the superconducting phase. Such Bogoliubov modes result from
dynamical feedback effects between single electron excitations and dynamical
local pairing fluctuations. We briefly recollect here our theoretical results
and confront them with the recent experimental findings.


title: Local approximation of the solutions of algebraic equations

abstract:
  A method of local approximation of holomorphic solutions of algebraic
equations is discussed


title: Cosmological Topologically Massive Gravitons and Photons

abstract:
  We study topologically massive (2+1)-dimensional gravity with a negative
cosmological constant. The masses of the linearized curvature excitations about
AdS_3 backgrounds are not only shifted from their flat background values but,
more surprisingly, split according to chirality. For all finite values of the
topological mass, we find a single bulk degree of freedom with positive energy,
and exhibit a complete set of normalizable, finite-energy wave packet
solutions. This model can also be written as a sum of two higher-derivative
SL(2,R) Chern--Simons theories, weighted by the central charges of the boundary
conformal field theory. At two particular "critical" values of the couplings,
one of these central charges vanishes, and linearized topologically massive
gravity becomes equivalent to topologically massive electromagnetism; however,
the physics of the bulk wave packets remains unaltered here.


title: Aspects of Integrability in AdS/CFT Duality

abstract:
  In this dissertation, we discuss how our understanding of the large-N
spectrum of AdS/CFT has been deepened by integrability-based approaches. We
begin with a comprehensive review of the integrability of the gauge theory
spin-chain and that of the string sigma model. In the light of the AdS/CFT
duality, they should be just two ways of describing the same underlying
integrability, and it is believed that the unified integrability can be
characterised by a set of Bethe ansatz equations which is valid for all values
of the 't Hooft coupling. By studying the asymptotic spectrum of the AdS/CFT in
the infinite spin/R-charge limit, we first identify the corresponding solitonic
counterparts in the context of the AdS/CFT, which are the so-called dyonic
giant magnons and the SYM magnon boundstates. Then we show that the S-matrix
computed directly from the string solitons scattering precisely reproduces the
prediction from the conjecture. We further perform an analyticity test by
studying the singularities of the conjectured magnon boundstate S-matrix and
checking the physicality conditions. These tests give strong positive supports
for the integrability of large-N AdS/CFT as well as the specific form of the
conjectured Bethe ansatz equations. Concerning the string theory integrability,
we also provide a detailed study of certain classical string solutions on AdS_5
x S^5. These are constructed in such a way they correspond to generic soliton
solutions of (Complex) sine/sinh-Gordon equations via the so-called Pohlmeyer
reduction procedure. Furthermore, we describe them in terms of
algebro-geometric data as finite-gap solutions, giving a complete map of the
elliptic string solutions.


title: Effect of the Trace Anomaly on the Cosmological Constant

abstract:
  It has been argued that the quantum (conformal) trace anomaly could
potentially provide us with a dynamical explanation of the cosmological
constant problem. In this paper, however, we show by means of a semiclassical
analysis that the trace anomaly does not affect the cosmological constant. We
construct the effective action of the conformal anomaly for flat FLRW
spacetimes consisting of local quadratic geometric curvature invariants.
Counterterms are thus expected to influence the numerical value of the
coefficients in the trace anomaly and we must therefore allow these parameters
to vary. We calculate the evolution of the Hubble parameter in quasi de Sitter
spacetime, where we restrict our Hubble parameter to vary slowly in time, and
in FLRW spacetimes. We show dynamically that a Universe consisting of matter
with a constant equation of state, a cosmological constant and the quantum
trace anomaly evolves either to the classical de Sitter attractor or to a
quantum trace anomaly driven one. When considering the trace anomaly truncated
to quasi de Sitter spacetime, we find a region in parameter space where the
quantum attractor destabilises. When considering the exact expression of the
trace anomaly, a stability analysis shows that whenever the trace anomaly
driven attractor is stable, the classical de Sitter attractor is unstable, and
vice versa. Semiclassically, the trace anomaly does not affect the classical
late time de Sitter attractor and hence it does not solve the cosmological
constant problem.


title:
A route to observing ponderomotive entanglement with optically trapped
  mirrors

abstract:
  The radiation pressure of two detuned laser beams can create a stable trap
for a suspended cavity mirror; here it is shown that such a configuration
entangles the output light fields via interaction with the mirror.
Intra-cavity, the opto-mechanical system can become entangled also. The degree
of entanglement is quantified spectrally using the logarithmic negativity.
Entanglement survives in the experimentally accessible regime of gram-scale
masses subject to thermal noise at room temperature.


title:
Azimuth quadrupole component spectra on transverse rapidity ${\bf y_t}$
  for identified hadrons from Au-Au collisions at $\sqrt{s_{NN}} =$ 200 GeV

abstract:
  I present the first isolation of azimuth quadrupole components from published
$v_2(p_t)$ data (called elliptic flow) as spectra on transverse rapidity $y_t$
for identified pions, kaons and lambdas/protons from minimum-bias Au-Au
collisions at 200 GeV. The form of the spectra on $y_t$ indicates that the
three hadron species are emitted from a common boosted source with boost
$\Delta y_{t0} \sim 0.6$. The quadrupole spectra have a L\'evy form similar to
the soft component of the single-particle spectrum, but with significantly
reduced ($\sim 0.7\times$) slope parameters $T$. Comparison of quadrupole
spectra with single-particle spectra suggests that the quadrupole component
comprises a small fraction ($< 5$%) of the total hadron yield, contradicting
the hydrodynamic picture of a thermalized, flowing bulk medium. The form of
$v_2(p_t)$ is, within a constant factor, the product of $p'_t$ ($p_t$ in the
boost frame) times the ratio of quadrupole spectrum to single-particle
spectrum. That ratio in turn implies that above 0.5 GeV/c the form of
$v_2(p_t)$ is dominated by the hard component of the single-particle spectrum
(interpreted as due to minijets). It is therefore unlikely that so-called {\em
constituent-quark scaling} attributed to $v_2$ is relevant to soft hadron
production mechanisms (e.g., chemical freezeout).


title:
Galaxy morphology, kinematics and clustering in a hydrodynamic
  simulation of a LambdaCDM universe

abstract:
  We explore galaxy properties and their link with environment and clustering
using a population of ~1000 galaxies formed in a high resolution hydrodynamic
simulation of the Lambda CDM cosmology. At the redshift we concentrate on, z=1,
the spatial resolution is 1.4 proper kpc/h and Milky-way sized disk galaxies
contain ~10^5 particles within their virial radii. We include supermassive
black hole accretion and feedback as well as a multiphase model for star
formation. We find that a number of familiar qualitative relationships hold
approximately between galaxy properties, for example, galaxies lie between two
broad extremes of type, where ``late'' types tend to be smaller in size, have
lower circular velocities, younger stars, higher star formation rates, larger
disk to bulge ratios and lower Sersic indices than ``early types''. As in
previous studies the stellar component of disk galaxies is not as rotationally
supported as in observations. Bulges contain too much of the stellar mass,
although disks do have scale lengths compatible with observations. The addition
of black hole physics to the simulations does not appear to have an impact on
the angular momentum results, nor do we find that it is affected in an
identical simulation with significantly lower mass resolution. Despite this, we
can profitably use the rank order of either disk to total ratio, Sersic index,
or galaxy age to separate galaxies into morphological classes and examine the
density-morphology relation and morphology dependence of clustering. We find
that while at redshift z=0, the well known preponderance of early types in
dense environments is seen, at z=1 the density-morphology relation becomes
flatter and late type galaxies are even seen to have a higher clustering
amplitude than early types (abridged).


title:
The Monitor project: the search for transits in the open cluster NGC
  2362

abstract:
  We present the results of a systematic search for transiting planets in a ~5
Myr open cluster, NGC 2362. We observed ~1200 candidate cluster members, of
which ~475 are believed to be genuine cluster members, for a total of ~100
hours. We identify 15 light curves with reductions in flux that pass all our
detection criteria, and 6 of the candidates have occultation depths compatible
with a planetary companion. The variability in these six light curves would
require very large planets to reproduce the observed transit depth. If we
assume that none of our candidates are in fact planets then we can place upper
limits on the fraction of stars with hot Jupiters (HJs) in NGC 2362. We obtain
99% confidence upper limits of 0.22 and 0.70 on the fraction of stars with HJs
(f_p) for 1-3 and 3-10 day orbits, respectively, assuming all HJs have a
planetary radius of 1.5R_Jup. These upper limits represent observational
constraints on the number of stars with HJs at an age <~10 Myr, when the vast
majority of stars are thought to have lost their protoplanetary discs. Finally,
we extend our results to the entire Monitor Project, a survey searching young,
open clusters for planetary transits, and find that the survey as currently
designed should be capable of placing upper limits on f_p near the observed
values of f_p in the solar neighbourhood.


title: The Invisible Z' at the LHC

abstract:
  We study the feasibility of observing an invisibly decaying Z' at the LHC
through the process pp -> ZZ' -> l+l-XX*, where X is any neutral, (quasi-)
stable particle, whether a Standard Model (SM) neutrino or a new state. The
measurement of the invisible width through this process facilitates both a
model independent measurement of Gamma_{Z' -> \bar{nu} nu} and potentially
detection of light neutral hidden states. Such particles appear in many models
where the Z' is a messenger to a hidden sector, and also if dark matter is
charged under the U(1)' of the Z'. We find that with as few as 30 fb^-1 of data
the invisibly decaying Z' can be observed at 5 sigma over SM background for a 1
TeV Z' with reasonable couplings. If the Z' does not couple to leptons and
therefore cannot be observed in the Drell-Yan channel, this process becomes a
discovery mode. For reasonable hidden sector couplings, masses up to 2 TeV can
be probed at the LHC. If the Z' does couple to leptons, then the rate for this
invisible decay is predicted by on-peak data and the presence of additional
hidden states can be searched for. With 100 fb^-1 of data, the presence of
excess decays to hidden states can be excluded at 95% C.L. if they comprise
20-30% of the total invisible cross section.


title: An entirely analytical cosmological model

abstract:
  The purpose of the present study is to show that in a particular cosmological
model, with an affine equation of state, one can obtain, besides the background
given by the scale factor, Hubble and deceleration parameters, a representation
in terms of scalar fields and, more important, explicit mathematical
expressions for the density contrast and the power spectrum. Although the model
so obtained is not realistic, it reproduces features observed in some previous
numerical studies and, therefore, it may be useful in the testing of numerical
codes and as a pedagogical tool.


title:
Prospects for cooling nanomechanical motion by coupling to a
  superconducting microwave resonator

abstract:
  Recent theoretical work has shown that radiation pressure effects can in
principle cool a mechanical degree of freedom to its ground state. In this
paper, we apply this theory to our realization of an opto-mechanical system in
which the motion of mechanical oscillator modulates the resonance frequency of
a superconducting microwave circuit. We present experimental data demonstrating
the large mechanical quality factors possible with metallic, nanomechanical
beams at 20 mK. Further measurements also show damping and cooling effects on
the mechanical oscillator due to the microwave radiation field. These data
motivate the prospects for employing this dynamical backaction technique to
cool a mechanical mode entirely to its quantum ground state.


title: Effects of new leptons in Electroweak Precision Data

abstract:
  We obtain limits on generic vector-like leptons at the TeV scale from
electroweak precision tests. These limits are complementary to the ones
obtained from lepton flavour violating processes. In general, the quality of
the global electroweak fit is comparable to the one for the Standard Model. In
the case of an extra neutrino singlet mixing with the muon or electron, the
global fit allows for a relatively large Higgs mass (M_H < 260 GeV at 90 %
C.L.), thus relaxing the tension between the direct LEP limit and the Standard
Model fit.


title: Critical fermi surfaces and non-fermi liquid metals

abstract:
  At certain quantum critical points in metals an entire Fermi surface may
disappear. A crucial question is the nature of the electronic excitations at
the critical point. Here we provide arguments showing that at such quantum
critical points the Fermi surface remains sharply defined even though the
Landau quasiparticle is absent. The presence of such a critical Fermi surface
has a number of consequences for the universal phenomena near the quantum
critical point which are discussed. In particular the structure of scaling of
the universal critical singularities can be significantly modified from more
familiar criticality. Scaling hypotheses appropriate to a critical fermi
surface are proposed. Implications for experiments on heavy fermion critical
points are discussed. Various phenomena in the normal state of the cuprates are
also examined from this perspective. We suggest that a phase transition that
involves a dramatic reconstruction of the Fermi surface might underlie a number
of strange observations in the metallic states above the superconducting dome.


title: Lorentz violating effects on a quantized two-level system

abstract:
  In this work, we consider the effects of the Lorentz-violating (LV) term $
v_{\mu}\bar{\psi}\gamma ^{\mu}\psi $ belonging to the fermion sector of the
extended standard model on the dynamics of a quantum two-level system. We
examine how its non-relativistic counterpart, ${(\mathbf{p}-e \mathbf{A})\cdot
}\mathbf{v}/{m_{e},}$ affects the Rabi oscillations of a two-level atom coupled
with a quantum cavity electromagnetic field. Taking an initial coherent field
state in a resonant cavity, it was found that the LV background increases the
Rabi frequency and the time interval between collapses and revivals of the
population inversion function. It was found that initial field states with low
mean number of photons are better probes in order to establish more stringent
upper bounds on the background magnitude. In particular, for an initial vacuum
state in the cavity the upper limit $\text{v}_{x}<10^{-10}eV$ was attained.


title: The Kinematics of Kepler's Supernova Remnant as revealed by Chandra

abstract:
  I determine the expansion of the supernova remnant of SN1604 (Kepler's
supernova) based on archival Chandra ACIS-S observations made in 2000 and 2006.
The measurements were done in several distinct energy bands, and were made for
the remnant as a whole, and for six individual sectors. The average expansion
parameter indicates that the remnant expands as $r \propto t^{0.5}$, but there
are significant differences in different parts of the remnant: the bright
northwestern part expands as $r \propto t^{0.35}$, whereas the rest of the
remnant's expansion shows an expansion $r \propto t^{0.6}$. The latter is
consistent with an explosion in which the outer part of the ejecta has a
negative power law slope for density ($\rho \propto v^{-n}$) of $n=7$, or with
an exponential density profile($\rho \propto \exp(-v/v_e)$). The expansion
parameter in the southern region, in conjunction with the shock radius,
indicate a rather low value (<5E50 erg) for the explosion energy of SN1604 for
a distance of 4 kpc. An higher explosion energy is consistent with the results,
if the distance is larger.
  The filament in the eastern part of the remnant, which is dominated by X-ray
synchrotron radiation seems to mark a region with a fast shock speed $r \propto
t^{0.7}$, corresponding to a shock velocity of v= 4200 km/s, for a distance to
SN1604 of 4 kpc. This is consistent with the idea that X-ray synchrotron
emission requires shock velocities in excess of ~2000 km/s.
  The X-ray based expansion measurements reported are consistent with results
based on optical and radio measurements, but disagree with previous X-ray
measurements based on ROSAT and Einstein observations.


title: Color Transparency in Semi-Inclusive Electroproduction of rho Mesons

abstract:
  We study the electroproduction of rho mesons in nuclei at intermediate
energies, deriving a treatment of the energy lost by the rho in each step of
multiple-scattering. This enables a close match between calculations and the
experimental kinematic conditions. A standard Glauber calculation is presented,
and then the effects of color-transparency are included. The influence of poor
experimental resolution on the extracted transparency is assessed. The effects
of $\rho$ meson decay inside the nucleus are examined, and are typically about
5 percent at most. This effect disappears rapidly as $Q^2$ increases from about
1 to 3 GeV$^2$, causing a rise in the transparency that is not attributable to
color transparency. The size of color transparency effects for C and Fe nuclei
is studied for values of $Q^2$ up to 10 GeV$^2$. The detailed results depend
strongly on the assumed value of the $\rho N$ cross section. The overall
effects of color transparency are greater than about 10 % for both nuclear
targets if $Q^2$ is greater than about 5 GeV$^2$.


title:
Classical Origin of the Spin of Relativistic Pointlike Particles and
  Geometric interpretation of Dirac Solutions

abstract:
  Spin of elementary particles is the only kinematic degree of freedom not
having classical corre- spondence. It arises when seeking for the
finite-dimensional representations of the Lorentz group, which is the only
symmetry group of relativistic quantum field theory acting on
multiple-component quantum fields non-unitarily. We study linear
transformations, acting on the space of spatial and proper-time velocities
rather than on coordinates. While ensuring the relativistic in- variance, they
avoid these two exceptions: they describe the spin degree of freedom of a
pointlike particle yet at a classical level and form a compact group hence with
unitary finite-dimensional rep- resentations. Within this approach changes of
the velocity modulus and direction can be accounted for by rotations of two
independent unit vectors. Dirac spinors just provide the quantum description of
these rotations.


title:
Fano and Dicke effects and spin polarization in a double Rashba-ring
  system side coupled to a quantum wire

abstract:
  The electronic transport in a system of two quantum rings side-coupled to a
quantum wire is studied via a single-band tunneling tight-binding Hamiltonian.
We derived analytical expressions for the conductance and spin polarization
when the rings are threaded by magnetic fluxes with Rashba spin-orbit
interaction. We show that by using the Fano and Dicke effects this system can
be used as an efficient spin-filter even for small spin orbit interaction and
small values of magnetic flux. We compare the spin-dependent polarization of
this design and the polarization obtained with one ring side coupled to a
quantum ring. As a main result, we find better spin polarization capabilities
as compared to the one ring design


title:
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses VII.
  Time delays and the Hubble constant from WFI J2033-4723

abstract:
  Gravitationally lensed quasars can be used to map the mass distribution in
lensing galaxies and to estimate the Hubble constant H0 by measuring the time
delays between the quasar images. Here we report the measurement of two
independent time delays in the quadruply imaged quasar WFI J2033-4723 (z =
1.66). Our data consist of R-band images obtained with the Swiss 1.2 m EULER
telescope located at La Silla and with the 1.3 m SMARTS telescope located at
Cerro Tololo. The light curves have 218 independent epochs spanning 3 full
years of monitoring between March 2004 and May 2007, with a mean temporal
sampling of one observation every 4th day. We measure the time delays using
three different techniques, and we obtain Dt(B-A) = 35.5 +- 1.4 days (3.8%) and
Dt(B-C) = 62.6 +4.1/-2.3 days (+6.5%/-3.7%), where A is a composite of the
close, merging image pair. After correcting for the time delays, we find R-band
flux ratios of F_A/F_B = 2.88 +- 0.04, F_A/F_C = 3.38 +- 0.06, and F_A1/F_A2 =
1.37 +- 0.05 with no evidence for microlensing variability over a time scale of
three years. However, these flux ratios do not agree with those measured in the
quasar emission lines, suggesting that longer term microlensing is present. Our
estimate of H0 agrees with the concordance value: non-parametric modeling of
the lensing galaxy predicts H0 = 67 +13/-10 km s-1 Mpc-1, while the Single
Isothermal Sphere model yields H0 = 63 +7/-3 km s-1 Mpc-1 (68% confidence
level). More complex lens models using a composite de Vaucouleurs plus NFW
galaxy mass profile show twisting of the mass isocontours in the lensing
galaxy, as do the non-parametric models. As all models also require a
significant external shear, this suggests that the lens is a member of the
group of galaxies seen in field of view of WFI J2033-4723.


title: Scanning Tunneling Spectroscopy of Graphene on Graphite

abstract:
  We report low temperature high magnetic field scanning tunneling microscopy
and spectroscopy of graphene flakes on graphite that exhibit the structural and
electronic properties of graphene decoupled from the substrate. Pronounced
peaks in the tunneling spectra develop with field revealing a Landau level
sequence that provides a direct way to identify graphene and to determine the
degree of its coupling to the substrate. The Fermi velocity and quasiparticle
lifetime, obtained from the positions and width of the peaks, provide access to
the electron-phonon and electron-electron interactions.


title: GRB 070306: A Highly Extinguished Afterglow

abstract:
  We report on the highly extinguished afterglow of GRB 070306 and the
properties of the host galaxy. An optical afterglow was not detected at the
location of the burst, but in near-infrared a doubling in brightness during the
first night and later power-law decay in the K band provided a clear detection
of the afterglow. The host galaxy is relatively bright, R ~ 22.8. An optical
low resolution spectrum revealed a largely featureless host galaxy continuum
with a single emission line. Higher resolution follow-up spectroscopy shows
this emission to be resolved and consisting of two peaks separated by 7 AA,
suggesting it to be [O II] at a redshift of z = 1.49594 +- 0.00006. The
infrared color H-K = 2 directly reveals significant reddening. By modeling the
optical/X-ray spectral energy distribution at t = 1.38 days with an
extinguished synchrotron spectrum, we derive A_V = 5.5 +- 0.6 mag. This is
among the largest values ever measured for a GRB afterglow and visual
extinctions exceeding unity are rare. The importance of early NIR observations
is obvious and may soon provide a clearer view into the once elusive 'dark
bursts'.


title: Human dynamics revealed through Web analytics

abstract:
  When the World Wide Web was first conceived as a way to facilitate the
sharing of scientific information at the CERN (European Center for Nuclear
Research) few could have imagined the role it would come to play in the
following decades. Since then, the increasing ubiquity of Internet access and
the frequency with which people interact with it raise the possibility of using
the Web to better observe, understand, and monitor several aspects of human
social behavior. Web sites with large numbers of frequently returning users are
ideal for this task. If these sites belong to companies or universities, their
usage patterns can furnish information about the working habits of entire
populations. In this work, we analyze the properly anonymized logs detailing
the access history to Emory University's Web site. Emory is a medium size
university located in Atlanta, Georgia. We find interesting structure in the
activity patterns of the domain and study in a systematic way the main forces
behind the dynamics of the traffic. In particular, we show that both linear
preferential linking and priority based queuing are essential ingredients to
understand the way users navigate the Web.

categories: cs.HC cond-mat.stat-mech cs.CY physics.soc-ph


title: Fuzzy Statistical Limits

abstract:
  Statistical limits are defined relaxing conditions on conventional
convergence. The main idea of the statistical convergence of a sequence l is
that the majority of elements from l converge and we do not care what is going
on with other elements. At the same time, it is known that sequences that come
from real life sources, such as measurement and computation, do not allow, in a
general case, to test whether they converge or statistically converge in the
strict mathematical sense. To overcome these limitations, fuzzy convergence was
introduced earlier in the context of neoclassical analysis and fuzzy
statistical convergence is introduced and studied in this paper. We find
relations between fuzzy statistical convergence of a sequence and fuzzy
statistical convergence of its subsequences (Theorem 2.1), as well as between
fuzzy statistical convergence of a sequence and conventional convergence of its
subsequences (Theorem 2.2). It is demonstrated what operations with fuzzy
statistical limits are induced by operations on sequences (Theorem 2.3) and how
fuzzy statistical limits of different sequences influence one another (Theorem
2.4). In Section 3, relations between fuzzy statistical convergence and fuzzy
convergence of statistical characteristics, such as the mean (average) and
standard deviation, are studied (Theorems 3.1 and 3.2).


title:
Description of the inelastic collision of two solitary waves for the BBM
  equation

abstract:
  We prove that the collision of two solitary waves of the BBM equation is
inelastic but almost elastic in the case where one solitary wave is small in
the energy space. We show precise estimates of the nonzero residue due to the
collision. Moreover, we give a precise description of the collision phenomenon
(change of size of the solitary waves).


title: The tropical $j$-invariant

abstract:
  If (Q,A) is a marked polygon with one interior point, then a general
polynomial f in K[x,y] with support A defines an elliptic curve C on the toric
surface X_A. If K has a non-archimedean valuation into the real numbers we can
tropicalize C to get a tropical curve Trop(C). If the Newton subdivision
induced by f is a triangulation, then Trop(C) will be a graph of genus one and
we show that the lattice length of the cycle of that graph is the negative of
the valuation of the j-invariant of C.


title:
Dynamical systems method for solving linear finite-rank operator
  equations

abstract:
  A version of the Dynamical Systems Method (DSM) for solving ill-conditioned
linear algebraic systems is studied in this paper. An {\it a priori} and {\it a
posteriori} stopping rules are justified. An iterative scheme is constructed
for solving ill-conditioned linear algebraic systems.


title: Super-Mathematics Functions

abstract:
  In this paper we talk about the so-called SuperMathematics Functions (SMF),
which often constiture the base for generating technical neo-geometrical
objects.


title:
The Evolution of Stellar Mass Density and its Implied Star Formation
  History

abstract:
  Using a compilation of measurements of the stellar mass density as a function
of redshift we can infer the cosmic star formation history. For z < 0.7 there
is good agreement between the two star formation histories. At higher redshifts
the instantaneous indicators suggest star formation rates larger than that
implied by the evolution of the stellar mass density. This discrepancy peaks at
z = 3 where instantaneous indicators suggest a star formation rate around 0.6
dex higher than those of the best fit to the stellar mass history. We discuss a
variety of explanations for this inconsistency, such as inaccurate dust
extinction corrections, incorrect measurements of stellar masses and a possible
evolution of the stellar initial mass function.


title: Structure and Interpretation of Computer Programs

abstract:
  Call graphs depict the static, caller-callee relation between "functions" in
a program. With most source/target languages supporting functions as the
primitive unit of composition, call graphs naturally form the fundamental
control flow representation available to understand/develop software. They are
also the substrate on which various interprocedural analyses are performed and
are integral part of program comprehension/testing. Given their universality
and usefulness, it is imperative to ask if call graphs exhibit any intrinsic
graph theoretic features -- across versions, program domains and source
languages. This work is an attempt to answer these questions: we present and
investigate a set of meaningful graph measures that help us understand call
graphs better; we establish how these measures correlate, if any, across
different languages and program domains; we also assess the overall, language
independent software quality by suitably interpreting these measures.


title:
High-dimensional analysis of semidefinite relaxations for sparse
  principal components

abstract:
  Principal component analysis (PCA) is a classical method for dimensionality
reduction based on extracting the dominant eigenvectors of the sample
covariance matrix. However, PCA is well known to behave poorly in the ``large
$p$, small $n$'' setting, in which the problem dimension $p$ is comparable to
or larger than the sample size $n$. This paper studies PCA in this
high-dimensional regime, but under the additional assumption that the maximal
eigenvector is sparse, say, with at most $k$ nonzero components. We consider a
spiked covariance model in which a base matrix is perturbed by adding a
$k$-sparse maximal eigenvector, and we analyze two computationally tractable
methods for recovering the support set of this maximal eigenvector, as follows:
(a) a simple diagonal thresholding method, which transitions from success to
failure as a function of the rescaled sample size
$\theta_{\mathrm{dia}}(n,p,k)=n/[k^2\log(p-k)]$; and (b) a more sophisticated
semidefinite programming (SDP) relaxation, which succeeds once the rescaled
sample size $\theta_{\mathrm{sdp}}(n,p,k)=n/[k\log(p-k)]$ is larger than a
critical threshold. In addition, we prove that no method, including the best
method which has exponential-time complexity, can succeed in recovering the
support if the order parameter $\theta_{\mathrm{sdp}}(n,p,k)$ is below a
threshold. Our results thus highlight an interesting trade-off between
computational and statistical efficiency in high-dimensional inference.


title:
X-Ray Powder Diffraction from Sub-Micron Crystals of Photosystem-1
  Membrane Protein

abstract:
  We demonstrate that powder diffraction data can be collected from sub-micron
crystals of a mbrane protein with nearly two orders of magnitude more atoms
than the molecules commonly used for powder diffraction. The crystals of
photosystem-1 protein were size-selected using a 500 nm pore- size filter and
delivered to a soft x-ray beam with a photon energy of 1.5 keV using a
dynamically focused micro-jet developed for the serial crystallography
experiment at beamline 9.0.1. The 10-micron jet places many such randomly
oriented crystals in the x-ray beam simultaneously resulting in a powder
diffraction pattern which extends to 28 angstrom resolution with just 200
seconds of x-ray exposure. The use of the jet for particle delivery allows for
a thin sample, appropriate for the soft x-rays used, and continuously refreshes
the crystals so that radiation damage is not possible. The small size of the
crystals requires the use of lower energy photons for increased scattering
strength and increased spacing between powder rings. The powder patterns
obtained in this way, from abundant nano-crystals, could be used to provide low
resolution molecular envelopes if phased using techniques such as compressive
sensing which do not require atomic resolution data. The results also serve to
test our aerojet injector system, with future application to femtosecond
diffraction in Free Electron X-ray Laser schemes, and for Serial
Crystallography using a single-file beam of aligned hydrated molecules.


title: Finite Size Giant Magnon

abstract:
  The quantization of the giant magnon away from the infinite size limit is
discussed. We argue that this quantization inevitably leads to string theory on
a Z_M-orbifold of S^5. This is shown explicitly and examined in detail in the
near plane-wave limit.


title:
Exact solutions for the D-dimensional spherical isotropic confined
  harmonic oscillator

abstract:
  We study the size effect on the energy levels of the D-dimensional isotropic
harmonic oscillator confined within a box of radius $r_c$ with impenetrable
walls. Two different approaches are used to obtain the energy eigenvalues and
eigenfunctions for D=1,2,...,5. In the first we solve the Schroedinger equation
exactly. In the second we use a series expansion of the wave function. The
numerical results obtained are extremely accurate; these values are reported
with 50 decimal places.


title: Learning Sequences

abstract:
  We describe the algorithms used by the ALEKS computer learning system for
manipulating combinatorial descriptions of human learners' states of knowledge,
generating all states that are possible according to a description of a
learning space in terms of a partial order, and using Bayesian statistics to
determine the most likely state of a student. As we describe, a representation
of a knowledge space using learning sequences (basic words of an antimatroid)
allows more general learning spaces to be implemented with similar algorithmic
complexity. We show how to define a learning space from a set of learning
sequences, find a set of learning sequences that concisely represents a given
learning space, generate all states of a learning space represented in this
way, and integrate this state generation procedure into a knowledge assessment
algorithm. We also describe some related theoretical results concerning
projections of learning spaces, decomposition and dimension of learning spaces,
and algebraic representation of learning spaces.


title:
Van Hove Singularity and Apparent Anisotropy in the Electron-Phonon
  Interaction in Graphene

abstract:
  We show that the electron-phonon coupling strength obtained from the slopes
of the electronic energy vs. wavevector dispersion relations, as often done in
analyzing angle-resolved photoemission data, can differ substantially from the
actual electron-phonon coupling strength due to the curvature of the bare
electronic bands. This effect becomes particularly important when the Fermi
level is close to a van Hove singularity. By performing {\it ab initio}
calculations on doped graphene we demonstrate that, while the apparent strength
obtained from the slopes of experimental photoemission data is highly
anisotropic, the angular dependence of the actual electron-phonon coupling
strength in this material is negligible.


title:
The effects of stellar populations on galaxy scaling relations in the
  6dF Galaxy Survey

abstract:
  We present an analysis of the stellar populations in a sample of ~7000
galaxies from the 6dF Galaxy Survey (6dFGS). We derive ages and metallicities
using stellar population models. We also derive dynamical masses and dynamical
mass-to-light ratios by combining central velocity dispersions with global
photometry in B, R and K bands. Together, these data allow to reduce the
degeneracies between age, metallicity and star formation burst-strength that
have limited previous studies. We find old galaxies exhibit a mass-metallicity
relation with slope d[Fe/H]/dlogM = 0.25, while young galaxies show slopes
consistent with zero. When we account for the effects of the mass-metallicity
relation, we obtain a single, consistent relation between mass-to-light ratio
and mass for old galaxies in all passbands. As we have accounted for stellar
population effects, this relation must have a dynamical origin. However, we
demonstrate that any simple trend between mass-to-light-ratio and mass or
luminosity is inconsistent with the observations, and that a more complex
relationship must exist. We find the central regions of galaxies often exhibit
young stellar populations. However it is only in the lowest-mass galaxies
(~10^{10} M$_{\odot}$) that these populations are evident in the global
photometry. In higher-mass galaxies, young central populations have decreasing
influence on the global photometry, with there being no discernible impact in
galaxies more massive than ~2x10^{11} M$_{\odot}$. We conclude that the young
stellar populations detected in spectroscopic studies are generally centrally
concentrated, and that there is an upper limit on the mass of star-forming
events in massive galaxies. These results have ramifications for mass-to-light
ratios estimated from photometric observations.


title: Free algebras and the Freiheitssatz

abstract:
  There have been gaps found in the proofs. The paper is withdrawn until
further notice.


title: An inverse source problem in optical molecular imaging

abstract:
  We study the direct and an inverse source problem for the radiative transfer
equation arising in optical molecular imaging. We show that for generic
absorption and scattering coefficients, the direct problem is well-posed and
the inverse one is uniquely solvable, with a stability estimate.


title: A Global 86GHz VLBI Survey of Compact Radio Sources

abstract:
  We present results from a large 86GHz global VLBI survey of compact radio
sources. The main goal of the survey is to increase by factors of 3--5 the
total number of objects accessible for future 3-mm VLBI imaging. The survey
observations reach the baseline sensitivity of 0.1Jy and image sensitivity of
better than 10 mJy/beam. The total of 127 compact radio sources have been
observed. The observations have yielded images for 109 sources, extending the
database of the sources imaged at 86GHz with VLBI observation by a factor of 5,
and only 6 sources have not been detected. The remaining 12 objects have been
detected but could not be imaged due to insufficient closure phase information.
Radio galaxies are less compact than quasars and BL Lacs on sub-milliarcsecond
scale. Flux densities and sizes of core and jet components of all imaged
sources have been estimated using Gaussian model fitting. From these
measurements, brightness temperatures have been calculated, taking into account
resolution limits of the data. The cores of 70% of the imaged sources are
resolved. The core brightness temperatures of the sources peak at $\sim
10^{11}$ K and only 1% have brightness temperatures higher than $10^{12}$ K.
Cores of Intraday Variable (IDV) sources are smaller in angular size than
non-IDV sources, and so yield higher brightness temperatures.


title: Algebraic reduction of the Ising model

abstract:
  We consider the Ising model on a cylindrical lattice of L columns, with
fixed-spin boundary conditions on the top and bottom rows. The spontaneous
magnetization can be written in terms of partition functions on this lattice.
We show how we can use the Clifford algebra of Kaufman to write these partition
functions in terms of L by L determinants, and then further reduce them to m by
m determinants, where m is approximately L/2. In this form the results can be
compared with those of the Ising case of the superintegrable chiral Potts
model. They point to a way of calculating the spontaneous magnetization of that
more general model algebraically.


title: A conjecture for the superintegrable chiral Potts model

abstract:
  We adapt our previous results for the ``partition function'' of the
superintegrable chiral Potts model with open boundaries to obtain the
corresponding matrix elements of e^{-\alpha H}, where H is the associated
hamiltonian. The spontaneous magnetization M_r can be expressed in terms of
particular matrix elements of e^{-\alpha H} S^r_1 \e^{-\beta H}, where S_1 is a
diagonal matrix.We present a conjecture for these matrix elements as an m by m
determinant, where m is proportional to the width of the lattice. The author
has previously derived the spontaneous magnetization of the chiral Potts model
by analytic means, but hopes that this work will facilitate a more algebraic
derivation, similar to that of Yang for the Ising model.


title: Nonvolatile memory with molecule-engineered tunneling barriers

abstract:
  We report a novel field-sensitive tunneling barrier by embedding C60 in SiO2
for nonvolatile memory applications. C60 is a better choice than ultra-small
nanocrystals due to its monodispersion. Moreover, C60 provides accessible
energy levels to prompt resonant tunneling through SiO2 at high fields.
However, this process is quenched at low fields due to HOMO-LUMO gap and large
charging energy of C60. Furthermore, we demonstrate an improvement of more than
an order of magnitude in retention to program/erase time ratio for a metal
nanocrystal memory. This shows promise of engineering tunnel dielectrics by
integrating molecules in the future hybrid molecular-silicon electronics.


title:
Statefinder Diagnostic for Quintessence with or without Thermal
  Interaction

abstract:
  The cosmological dynamics of minimally coupled scalar field that couples to
the background matter with thermal interactions is investigated by using
statefinder diagnostics. The time evolution of the statefinder pairs $\{r,s\}$
and $\{r,q\}$ are obtained under the circumstance that different values of
model parameters are chosen. We show that the thermal coupling term does not
affect the location of the late-time attractor, but exert an influence on the
evolution of the statefinder parameters. The most notable feature of the $r-s$
plane for the thermal coupling model which is distinguished from the other dark
energy models is that some part of the curve with thermal coupling can form a
closed loop in the second quadrant ($r>1,s<0$).


title: Probability distribution of the resistance of a random network

abstract:
  The probability density of the resistance of a two dimensional rectangular
network between two conducting plates is calculated. The nodes form an $M$ by
$N$ lattice, and each edge has a random resistance. The Monte Carlo method is
used.


title:
CuO chain statistics, charge transfer and Tc(x) dependence in
  YBa2Cu3O6+x, Y0.9(Ca)0.1Ba2Cu3O6+x, and Y0.8(Ca)0.2Ba2Cu3O6+x

abstract:
  x dependences of Tc in YBa2Cu3O6+x and Y1-b(Ca)bBa2Cu3O6+x (b=0.1 and b=0.2)
have been calculated assuming that the net doping of CuO2 layers is a sum of
contributions from CuO chains and from substitution of Y3+ by Ca2+. We applied
the concept of minimal (critical) chain length lcr needed to trigger charge
transfer from chains to planes. The model proposed assumes that only a certain
part, say kappa, of those chain-holes that are created beyond the first lcr-2
holes in chains of length l>lcr, are able to attract electrons from CuO2
bilayer. Our analysis points to the conclusion that parameter lcr should be
equal to 4 (four oxygen atoms in a chain), or very close to it (3, or 5).
Calculated x dependences of doping, p(x), at constant (room) temperature and
for three different substitution levels b=0, 0.1, and 0.2, are found to be in
excellent agreement with available experimental data. These p(x) dependences
are combined with universal (parabolic) phase relation Tc(p) to obtain three
Tc(x) dependences that also remarkably correlate with those reported in
experiments. The results obtained indicate that in long chains (x=1) the
probability for a chain-hole to capture an electron (expressing hole ability to
become transferred) decreases with the concentration of 3d Cu electrons in CuO2
layers, ranking from kappa=40%(42%) in YBa2Cu3O6+x, over kappa=36% in
Y0.9(Ca)0.1Ba2Cu3O6+x to kappa=33% in Y0.8(Ca)0.2Ba2Cu3O6+x. We estimate that
in these three systems the wavelength of charge corrugations in long chains (at
x=1) should be ranking around lambda=1.38nm, lambda=1.25nm, lambda=1.20nm,
respectively.


title: On semistable principal bundles over a complex projective manifold

abstract:
  Let G be a simple linear algebraic group defined over the complex numbers.
Fix a proper parabolic subgroup P of G and a nontrivial antidominant character
\chi of P. We prove that a holomorphic principal G-bundle E over a connected
complex projective manifold M is semistable and the second Chern class of its
adjoint bundle vanishes in rational cohomology if and only if the line bundle
over E/P defined by \chi is numerically effective. Similar results remain valid
for principal bundles with a reductive linear algebraic group as the structure
group. These generalize an earlier work of Y. Miyaoka where he gave a
characterization of semistable vector bundles over a smooth projective curve.
Using these characterizations one can also produce similar criteria for the
semistability of parabolic principal bundles over a compact Riemann surface.


title:
State-resolved rotational cross sections and thermal rate coefficients
  for ortho-/para-H2+HD at low temperatures and HD+HD elastic scattering

abstract:
  Results for quantum mechanical calculations of the integral cross sections
and corresponding thermal rate coefficients for para-/ortho-H2+HD collisions
are presented. Because of significant astrophysical interest in regard to the
cooling of primodial gas the low temperature limit of para-/ortho-H2+HD is
investigated. Sharp resonances in the rotational state-resolved cross sections
have been calculated at low energies. These resonances are important and
significantly contribute to the corresponding rotational state-resolved thermal
rate coefficients, particularly at low temperatures, that is less than $T \sim
100$K. Additionally in this work, the cross sections for the elastic HD+HD
collision have also been calculated. We obtained quite satisfactory agreement
with the results of other theoretical works and experiments.


title:
Ergodic Properties of a Class of Discrete Abelian Group Extensions of
  Rank-One Transformations

abstract:
  We define a class of discrete abelian group extensions of rank-one
transformations and establish necessary and sufficient conditions for these
extensions to be power weakly mixing. We show that all members of this class
are multiply recurrent. We then study conditions sufficient for showing that
cartesian products of transformations are conservative for a class of
invertible infinite measure-preserving transformations and provide examples of
these transformations.


title: Electromagnetic Characteristics of States $^{172}Yb$}

abstract:
  To describe the ground (gr) and excited states of even-even deformed nuclei
with the phenomenological model, which takes into account the mixing ground
$(gr)$, $0^{+}_{2}(\beta_1)$--, $0^{+}_{3}(\beta_2)$--,
$2^{+}_{1}(\gamma_1)$--, $2^{+}_{2}(\gamma_2)$-- and $K^{\pi}=1^{+}_{\nu}$
rotational bands the calculation has been done for the isotope $^{172}Yb$. The
energy specterum is described. The reduced probability of electric quadrupole,
monopole and dipole magnetic transitions from the states $0^{+}_{\nu}$ and
$2^{+}_{\nu}$ - bands to the ground $(gr)$ state band is calculated. A non
adiabatic effect in the energy and electromagnetic characteristics is
discussed.


title:
Constructing the Optimal Solutions to the Undiscounted Continuous-Time
  Infinite Horizon Optimization Problems

abstract:
  We aim to construct the optimal solutions to the undiscounted continuous-time
infinite horizon optimization problems, the objective functionals of which may
be unbounded. We identify the condition under which the limit of the solutions
to the finite horizon problems is optimal for the infinite horizon problems
under the overtaking criterion.


title: The invertible double of elliptic operators

abstract:
  First, we review the Dirac operator folklore about basic analytic and
geometrical properties of operators of Dirac type on compact manifolds with
smooth boundary and on closed partitioned manifolds and show how these
properties depend on the construction of a canonical invertible double and are
related to the concept of the Calderon projection. Then we summarize a recent
construction of a canonical invertible double for general first order elliptic
differential operators over smooth compact manifolds with boundary. We derive a
natural formula for the Calderon projection which yields a generalization of
the famous Cobordism Theorem. We provide a list of assumptions to obtain a
continuous variation of the Calderon projection under smooth variation of the
coefficients. That yields various new spectral flow theorems. Finally, we
sketch a research program for confining, respectively closing, the last re-
maining gaps between the geometric Dirac operator type situation and the
general linear elliptic case.


title:
Macroscopic quantum self-trapping in a Bose-Josephson junction with
  fermions

abstract:
  We study the macroscopic quantum self-trapping effect in a mixture of
Bose-Einstein condensate and a large number of quantum degenerate fermions,
trapped in a double-well potential with a variable separation between the
wells. The large number of fermions localized in each well form quasi-static
impurities that affect the dynamics of the bosonic cloud. Our semi-analytical
analysis based on a mean-field model shows that main features of macroscopic
quantum self trapping in a pure bosonic system are radically modified by the
influence of fermions, with both the onset of self-trapping and properties of
the self-trapped state depending on the fermion concentration as well as on the
type of inter-species interaction. Remarkably, repulsive inter-species
interaction leads to population inversion of the bosonic energy levels in the
trapping potential and hence to the inversion of symmetry of the macroscopic
wavefunction. Realistic physical estimates are given based on experimental
parameters for a $^{40}$K-$^{87}$Rb system.


title:
Stateless and Delivery Guaranteed Geometric Routing on Virtual
  Coordinate System

abstract:
  Stateless geographic routing provides relatively good performance at a fixed
overhead, which is typically much lower than conventional routing protocols
such as AODV. However, the performance of geographic routing is impacted by
physical voids, and localization errors. Accordingly, virtual coordinate
systems (VCS) were proposed as an alternative approach that is resilient to
localization errors and that naturally routes around physical voids. However,
VCS also faces virtual anomalies, causing their performance to trail geographic
routing. In existing VCS routing protocols, there is a lack of an effective
stateless and delivery guaranteed complementary routing algorithm that can be
used to traverse voids. Most proposed solutions use variants of flooding or
blind searching when a void is encountered. In this paper, we propose a
spanning-path virtual coordinate system which can be used as a complete routing
algorithm or as the complementary algorithm to greedy forwarding that is
invoked when voids are encountered. With this approach, and for the first time,
we demonstrate a stateless and delivery guaranteed geometric routing algorithm
on VCS. When used in conjunction with our previously proposed aligned virtual
coordinate system (AVCS), it out-performs not only all geometric routing
protocols on VCS, but also geographic routing with accurate location
information.


title:
Limit of the Solutions for the Finite Horizon Problems as the Optimal
  Solution to the Infinite Horizon Optimization Problems

abstract:
  We aim to generalize the results of Cai and Nitta (2007) by allowing both the
utility and production function to depend on time. We also consider an
additional intertemporal optimality criterion. We clarify the conditions under
which the limit of the solutions for the finite horizon problems is optimal
among all attainable paths for the infinite horizon problems under the
overtaking criterion, as well as the conditions under which such a limit is the
unique optimum under the sum-of-utilities criterion. The results are applied to
a parametric example of the one-sector growth model to examine the impacts of
discounting on optimal paths.


title:
Time-dependent Gutzwiller theory of pairing fluctuations in the Hubbard
  model

abstract:
  We present a method to compute pairing fluctuations on top of the Gutzwiller
approximation (GA). Our investigations are based on a charge-rotational
invariant GA energy functional which is expanded up to second order in the pair
fluctuations. Equations of motion for the fluctuations lead to a renormalized
ladder type approximation. Both spectral functions and corrections to static
quantities, like the ground-state energy, are computed. The quality of the
method is examined for the single-band Hubbard model where we compare the
dynamical pairing correlations for s- and d-wave symmetries with exact
diagonalizations and find a significant improvement with respect to analogous
calculations done within the standard Hartree-Fock ladder approximation. The
technique has potential applications in the theory of Auger spectroscopy,
superconductivity, and cold atom physics.


title:
Critical Zeeman Splitting of Fermi Superfluidity at Infinite Scattering
  Length

abstract:
  We determine the critical Zeeman energy splitting for Fermi superfluidity at
infinite s-wave scattering length according to the Monte Carlo and experimental
results of the equations of state. Based on the universality hypothesis, we
show that there exist two critical fields $H_{c1}$ and $H_{c2}$, between which
a superfluid-normal mixed phase is energetically favored, and model-independent
formulae for $H_{c1}$, $H_{c2}$ and the critical population imbalance $P_c$ are
derived. Using recent Monte Carlo and experimental results of $P_c$, $H_{c1}$
and $H_{c2}$ are determined. It is found $H_{c1}=0.41\epsilon_{\text F}$ and
$H_{c2}=0.50\epsilon_{\text F}$, with $\epsilon_{\text F}$ being the Fermi
energy of non-interacting gas.


title:
The star formation efficiency and its relation to variations in the
  initial mass function

abstract:
  We investigate how the dynamical state of a turbulently supported, 1000 solar
mass, molecular cloud affects the properties of the cluster it forms, focusing
our discussion on the star formation efficiency (SFE) and the initial mass
function (IMF). A variety of initial energy states are examined in this paper,
ranging from clouds with PE = 0.1 KE to clouds with PE = 10 KE, and for both
isothermal and piece-wise polytropic equations of state (similar to that
suggested by Larson). It is found that arbitrary star formation efficiencies
are possible, with strongly unbound clouds yielding very low star formation
efficiencies. We suggest that the low star formation efficiency in the
Maddelena cloud may be a consequence of the relatively unbound state of its
internal structure. It is also found that competitive accretion results in the
observed IMF when the clouds have initial energy states of PE >= KE. We show
that under such conditions the shape of the IMF is independent of time in the
calculations. This demonstrates that the global accretion process can be
terminated at any stage in the cluster's evolution, while still yielding a
distribution of stellar masses that is consistent with the observed IMF. As the
clouds become progressively more unbound, competitive accretion is less
important and the protostellar mass function flattens. These results predict
that molecular clouds should be permeated with a distributed population of
stars that follow a flatter than Salpeter IMF.


title: Involutive Yang-Baxter Groups

abstract:
  In 1992 Drinfeld posed the question of finding the set theoretic solutions of
the Yang-Baxter equation. Recently, Gateva-Ivanova and Van den Bergh and
Etingof, Schedler and Soloviev have shown a group theoretical interpretation of
involutive non-degenerate solutions. Namely, there is a one-to-one
correspondence between involutive non-degenerate solutions on finite sets and
groups of $I$-type. A group $\mathcal{G}$ of $I$-type is a group isomorphic to
a subgroup of the natural semidirect product of $Fa_n$, the free abelian group
of rank $n$, by $Sym_n$, the symmetric group on $n$ letters, so that the
projection onto $Fa_n$ is a bijective map. The projection of $\mathcal{G}$ onto
$Sym_n$ we call an involutive Yang-Baxter group (IYB group). This suggests the
following strategy to attack Drinfeld's problem for involutive non-degenerate
set theoretic solutions. First classify the IYB groups and second, for a given
IYB group $G$, classify the groups of $I$-type with $G$ as associated IYB
group. It is known that every IYB group is solvable. In this paper some results
supporting the converse of this property are obtained. More precisely, we show
that some classes of groups are IYB groups. We also give a non-obvious method
to construct infinitely many groups of $I$-type (and hence infinitely many
involutive non-degenerate set theoretic solutions of the Yang-Baxter equation)
with a prescribed associated IYB group.


title: Letter to the editor. NAA and JFK: Can revisionism take us home?

abstract:
  Occasionally during the course of the human learning experience we are faced
with an anomaly. An aberration of sorts, which try as we might, defies
appropriate classification. The recent paper by Spiegelman et al.--Chemical and
forensic analysis of JFK assassination bullet lots: Is a second shooter
possible?--is one such aberration. It is riddled with both misconceptions and
errors of fact. Purporting to cast doubt on the NAA (neutron activation
analysis) work conducted by Dr. Vincent Guinn in the investigation of the
assassination of President John F. Kennedy, it fails miserably. The paper
offers two central conclusions, one which is demonstrably false, and the other
which is specious. The authors opine; ``If the assassination fragments are
derived from three or more separate bullets, then a second assassin is likely,
as the additional bullet would not be attributable to the main suspect, Mr.
Oswald.'' This statement relating to the likelihood of a second assassin based
on the premise of three or more separate bullets is demonstrably false. The
available evidence indicates that Oswald fired three shots, one of which is
believed to have missed. However, on the off chance that all three shots hit
(even though there is absolutely no other supporting forensic evidence for such
a notion) those three shots alone in no way would indicate then that ``a second
assassin is likely.'' The authors' erroneous conclusion was achieved because
they have either been misled (which I personally believe is the case) or they
simply aren't familiar with the evidence.


title:
Ab initio study of the vibrational properties of crystalline TeO2: The
  alpha, beta, and gamma phases

abstract:
  Based on density functional perturbation theory, we have studied the
vibrational properties of three crystalline phases of tellurium dioxide:
paratellurite alpha-TeO2, tellurite beta-TeO2, and the new phase gamma-TeO2,
recently identified experimentally. Calculated Raman and IR spectra are in good
agreement with available experimental data. The vibrational spectra of alpha-
and beta-TeO2 can be interpreted in terms of vibrations of TeO2 molecular
units.


title: Response to the Letter to the Editor

abstract:
  This paper has attracted interest around the world from the media (both TV
and newspapers). In addition, we have received letters, emails and telephone
calls. One of our favorites was a voicemail message asking us to return a call
to Australia at which point we would learn who really killed JFK. We welcome
the opportunity to respond to the letter to the editor from Mr. Fiorentino. Mr.
Fiorentino claims that our ``statement relating to the likelihood of a second
assassin based on the premise of three or more separate bullets is demonstrably
false.'' In response we would like to simply quote from page 327 of Gerald
Posner's book Case Closed, one of the most well known works supporting the
single assassin theory: ``If Connally was hit by another bullet, it had to be
fired from a second shooter, since the Warren Commission's own reconstructions
showed that Oswald could not have operated the bolt and refired in 1.4
seconds.'' Mr. Fiorentino also claims that the ``second fatal flaw is the use
of a rather uncomplicated formula based on Bayes Theorem.'' Let $E$ denote the
evidence and $T$ denote the theory that there were just two bullets (and hence
a single shooter). We used Bayes Theorem to hypothetically calculate $P(T|E)$
from $P(E|T)$ and the prior probability $P(T)$. In order to make $P(T|E)$ ten
times more likely than $P(\bar{T}|E)$, the ratio of the prior probabilities
[i.e., $P(T) / P(\bar{T})$] would have to be greater than 15. Thus, we again
conclude that this casts serious doubt on Dr. Guinn's conclusion that the
evidence supported just two bullets. Sadly, this is far from the first time
that probability has been misunderstood and/or misapplied in a case of public
interest. A notable British example is the Clark case. See Nobles and Schiff
(2005) for details. Finally, we welcome and, in fact, encourage members of the
scientific community to provide alternative analyses of the data.


title: Crime and punishment in scientific research

abstract:
  Typical arguments against scientific misconduct generally fail to support
current policies on research fraud: they may not prove wrong what is usually
considered research misconduct and they tend to make wrong things that are not
normally seen as scientific fraud, in particular honest errors. I also point
out that sanctions are not consistent with the reasons why scientific fraud is
supposed to be wrong either. Moreover honestly seeking truth should not be
contrived as a moral rule -- it is instead a necessary condition for work to
qualify as scientific.
  Keywords: cheating; ethics; fabrication; falsification; integrity;
plagiarism; research fraud; scientific misconduct.


title:
Effects of chemical pressure on the Fermi surface and band dispersion in
  the electron-doped high-Tc superconductors

abstract:
  We have performed angle-resolved photoemission spectroscopy (ARPES)
measurements and first-principles electronic structure calculations on the
electron-doped high-Tc superconductors Ln1.85Ce0.15CuO4 (Ln = Nd, Sm, and Eu).
The observed Fermi surface and band dispersion show such changes that with
decreasing ionic size of Ln3+, the curvature of the Fermi surface or -t'/t
decreases, where t and t' are transfer integrals between the nearest-neighbor
and next-nearestneighbor Cu sites, respectively. The increase of t with
chemical pressure is found to be significant, which may explain the apparently
inconsistent behavior seen in the hole-doped La2-xSrxCuO4 under epitaxial
strain [M. Abrecht et al., Phys. Rev. Lett. 91, 057002 (2003)]. A gap due to
the antiferromagnetism opens even in the nodal region for the Sm and Eu
compounds, and the gap size increases in going from Ln = Sm to Eu.


title: Canonical sampling through velocity-rescaling

abstract:
  We present a new molecular dynamics algorithm for sampling the canonical
distribution. In this approach the velocities of all the particles are rescaled
by a properly chosen random factor. The algorithm is formally justified and it
is shown that, in spite of its stochastic nature, a quantity can still be
defined that remains constant during the evolution. In numerical applications
this quantity can be used to measure the accuracy of the sampling. We
illustrate the properties of this new method on Lennard-Jones and TIP4P water
models in the solid and liquid phases. Its performance is excellent and largely
independent on the thermostat parameter also with regard to the dynamic
properties.


title: Neutral Hydrogen and Star Formation in the Coma-Abell1367 Supercluster

abstract:
  We present preliminary results of a multi-wavelength study focused on the
evolution of spiral galaxies in the UV-optical colour-magnitude (CM) diagram.
By combining HI, UV and optical observations of the Coma-Abell1367 supercluster
we are able to identify galaxies at different stages of their evolution: from
healthy star-forming galaxies, to blue HI-poor spirals and transition objects.
Our analysis shows that galaxies in the transition region are likely to be the
progeny of healthy spirals, whose star-formation has been quenched by the harsh
cluster environment. This result suggests that, at least in clusters of
galaxies, the migration of galaxies from the blue to the red sequence might be
due to environmental processes.


title: Ultradiscretization of solvable one-dimensional chaotic maps

abstract:
  We consider the ultradiscretization of a solvable one-dimensional chaotic map
which arises from the duplication formula of the elliptic functions. It is
shown that ultradiscrete limit of the map and its solution yield the tent map
and its solution simultaneously. A geometric interpretation of the dynamics of
the tent map is given in terms of the tropical Jacobian of a certain tropical
curve. Generalization to the maps corresponding to the $m$-th multiplication
formula of the elliptic functions is also discussed.


title:
Calibrating Car-Following Models using Trajectory Data: Methodological
  Study

abstract:
  The car-following behavior of individual drivers in real city traffic is
studied on the basis of (publicly available) trajectory datasets recorded by a
vehicle equipped with an radar sensor. By means of a nonlinear optimization
procedure based on a genetic algorithm, we calibrate the Intelligent Driver
Model and the Velocity Difference Model by minimizing the deviations between
the observed driving dynamics and the simulated trajectory when following the
same leading vehicle. The reliability and robustness of the nonlinear fits are
assessed by applying different optimization criteria, i.e., different measures
for the deviations between two trajectories. The obtained errors are in the
range between~11% and~29% which is consistent with typical error ranges
obtained in previous studies. In addition, we found that the calibrated
parameter values of the Velocity Difference Model strongly depend on the
optimization criterion, while the Intelligent Driver Model is more robust in
this respect. By applying an explicit delay to the model input, we investigated
the influence of a reaction time. Remarkably, we found a negligible influence
of the reaction time indicating that drivers compensate for their reaction time
by anticipation. Furthermore, the parameter sets calibrated to a certain
trajectory are applied to the other trajectories allowing for model validation.
The results indicate that ``intra-driver variability'' rather than
``inter-driver variability'' accounts for a large part of the calibration
errors. The results are used to suggest some criteria towards a benchmarking of
car-following models.


title: On the Berg--Chen--Ismail theorem and the Nevanlinna-Pick problem

abstract:
  In 2002 C. Berg, Y. Chen, and M. Ismail found a nice relation between the
determinancy of the Hamburger moment problem and asymptotic behavior of the
smallest eigenvalues of the corresponding Hankel matrices. We investigate
whether an analog of this statement holds for the Nevanlinna--Pick
interpolation problem.


title:
Statistical advances and challenges for analyzing correlated high
  dimensional SNP data in genomic study for complex diseases

abstract:
  Recent advances of information technology in biomedical sciences and other
applied areas have created numerous large diverse data sets with a high
dimensional feature space, which provide us a tremendous amount of information
and new opportunities for improving the quality of human life. Meanwhile, great
challenges are also created driven by the continuous arrival of new data that
requires researchers to convert these raw data into scientific knowledge in
order to benefit from it. Association studies of complex diseases using SNP
data have become more and more popular in biomedical research in recent years.
In this paper, we present a review of recent statistical advances and
challenges for analyzing correlated high dimensional SNP data in genomic
association studies for complex diseases. The review includes both general
feature reduction approaches for high dimensional correlated data and more
specific approaches for SNPs data, which include unsupervised haplotype
mapping, tag SNP selection, and supervised SNPs selection using statistical
testing/scoring, statistical modeling and machine learning methods with an
emphasis on how to identify interacting loci.


title: Dissipative Two-Electron Transfer

abstract:
  We investigate non-equilibrium two-electron transfer in a model redox system
represented by a two-site extended Hubbard model and embedded in a dissipative
environment. The influence of the electron-electron interactions and the
coupling to a dissipative bosonic bath on the electron transfer is studied in
different temperature regimes. At high temperatures Marcus transfer rates are
evaluated and at low temperatures, we calculate equilibrium and non-equilibrium
population probabilities of the donor and acceptor with the non-perturbative
Numerical Renormalization Group approach. We obtain the non-equilibrium
dynamics of the system prepared in an initial state of two electrons at the
donor site and identify conditions under which the electron transfer involves
one concerted two-electron step or two sequential single-electron steps. The
rates of the sequential transfer depend non-monotonically on the difference
between the inter-site and on-site Coulomb interaction which become
renormalized in the presence of the bosonic bath. If this difference is much
larger than the hopping matrix element, the temperature as well as the
reorganization energy, simultaneous transfer of both electrons between donor
and acceptor can be observed.


title: Energetics of quantum correlations

abstract:
  We consider a photo--Carnot engine that consists of a single--mode radiation
field in an optical cavity. One the heat reservoirs is made of a beam of
thermally entangled pairs of two--level atoms that interact resonantly with the
cavity. We express the thermodynamic efficiency of the engine in terms of the
quantum discord of the atomic pair and find that it can exceed its classical
value. Our results show that useful work can be extracted from quantum
correlations, indicating that the latter are a valuable resource in quantum
thermodynamics.


title: Electromagnetic mean squared radii of Lambda(1405) in chiral dynamics

abstract:
  The electromagnetic mean squared radii, <r^2>_E and <r^2>_M, of Lambda(1405)
are calculated in the chiral unitary model. We describe the excited baryons as
dynamically generated resonances in the octet meson and octet baryon
scattering. We evaluate values of <r^2>_E and <r^2>_M for the Lambda(1405) on
the resonance pole and obtain their complex values. We also consider
Lambda(1405) obtained by neglecting decay channels. For the latter case, we
obtain negative and larger absolute electric mean squared radius than that of
typical ground state baryons. This implies that Lambda(1405) has structure that
K^- is widely spread around p.


title:
Engineering the quantum transport of atomic wavefunctions over
  macroscopic distances

abstract:
  The manipulation of matterwave represents a milestone in the history of
quantum mechanics. It was at the basis of its experimental validation through
the observation of diffraction of matter on crystals, as well as grating and
Young's double-slit interference with electrons, neutron, atoms and molecules.
More recently matterwave manipulation has become a building block in the
implementation of quantum devices such as quantum sensors and it plays an
essential role in many proposals for implementing quantum computers. In this
letter we coherently control the spatial extent of the wavefunction by
reversibly stretching and shrinking the wavefunction over a millimeter
distance. The remarkable experimental simplicity of the scheme would ease
applications in the field of quantum transport and quantum computing.


title: Freeze-out by bulk viscosity driven instabilities

abstract:
  We describe a new scenario (first introduced in [G. Torrieri, B.
Tom\'a\v{s}ik and I. Mishustin, Phys. Rev. C \textbf{77}, 034903 (2008)]) for
freezeout in heavy ion collisions that could solve the lingering problems
associated with the so-called HBT puzzle. We argue that bulk viscosity
increases as $T$ approaches $T_c$. The fluid {then} becomes unstable against
small perturbations, and fragments into clusters of a size much smaller than
the total size of the system. These clusters maintain the pre-existing
outward-going flow, as a spray of droplets, but develop no flow of their own,
and hadronize by evaporation. We show that this scenario can explain HBT data
and suggest how it can be experimentally tested.


title:
Aspects of metallic low-temperature transport in Mott-insulator/
  band-insulator superlattices: optical conductivity and thermoelectricity

abstract:
  We investigate the low-temperature electrical and thermal transport
properties in atomically precise metallic heterostructures involving
strongly-correlated electron systems. The model of the Mott-insulator/
band-insulator superlattice was discussed in the framework of the slave-boson
mean-field approximation and transport quantities were derived by use of the
Boltzmann transport equation in the relaxation-time approximation. The results
for the optical conductivity are in good agreement with recently published
experimental data on (LaTiO$_3)_N$/(SrTiO$_3)_M$ superlattices and allow us to
estimate the values of key parameters of the model. Furthermore, predictions
for the thermoelectric response were made and the dependence of the Seebeck
coefficient on model parameters was studied in detail. The width of the
Mott-insulating material was identified as the most relevant parameter, in
particular, this parameter provides a way to optimize the thermoelectric power
factor at low temperatures.


title: Stationary Rotating Strings as Relativistic Particle Mechanics

abstract:
  Stationary rotating strings can be viewed as geodesic motions in appropriate
metrics on a two-dimensional space. We obtain all solutions describing
stationary rotating strings in flat spacetime as an application. These rotating
strings have infinite length with various wiggly shapes. Averaged value of the
string energy, the angular momentum and the linear momentum along the string
are discussed.


title:
Combined effects due to phase, intensity and contrast in electrooptic
  modulation. Application to ferroelectric materials

abstract:
  The combination of phase, intensity, and contrast effects during electrooptic
modulation is theoretically and exper- imentally investigated. One consequence
of this combination is the modification of the amplitude of the
single-frequency signals which are commonly used as working points for
electrooptic mod- ulators and for the measurements of the electrooptic
coefficients. Another consequence of direct intensity modulation is to shift
the double-frequency points of the transfer function from the positions they
normally occupy at the intensity extrema. They can even make them disappear if
the direct intensity modulation is stronger than the phase modulation. Such
phenomena are expected with any ferroelectric material in which a significant
part of the incident light is deflected or scattered by domain walls or grain
boundaries. They can lead to considerable mistakes in the determination of the
electrooptic coefficients. Appropriate procedures to extract the different
contributions are explained. Experimental results in rubidium hydrogen selenate
are given, and consequences of the working of electrooptic modulators are
discussed.


title: Reflective visualization and verbalization of unconscious preference

abstract:
  A new method is presented, that can help a person become aware of his or her
unconscious preferences, and convey them to others in the form of verbal
explanation. The method combines the concepts of reflection, visualization, and
verbalization. The method was tested in an experiment where the unconscious
preferences of the subjects for various artworks were investigated. In the
experiment, two lessons were learned. The first is that it helps the subjects
become aware of their unconscious preferences to verbalize weak preferences as
compared with strong preferences through discussion over preference diagrams.
The second is that it is effective to introduce an adjustable factor into
visualization to adapt to the differences in the subjects and to foster their
mutual understanding.


title:
Investigation of sp carbon chain interaction with silver nanoparticles
  by Surface Enhanced Raman Scattering

abstract:
  Surface Enhanced Raman Spectroscopy (SERS) is exploited here to investigate
the interaction of isolated sp carbon chains (polyynes) in a methanol solution
with silver nanoparticles. Hydrogen-terminated polyynes show a strong
interaction with silver colloids used as the SERS active medium revealing a
chemical SERS effect. SERS spectra after mixing polyynes with silver colloids
show a noticeable time evolution. Experimental results, supported by density
functional theory (DFT) calculations of the Raman modes, allow us to
investigate the behavior and stability of polyynes of different lengths and the
overall sp conversion towards sp2 phase.


title: Quintessence: a mini-review

abstract:
  Models where the accelerated expansion of our Universe is caused by a
quintessence scalar field are reviewed. In the framework of high energy
physics, the physical nature of this field is discussed and its interaction
with ordinary matter is studied and explicitly calculated. It is shown that
this coupling is generically too strong to be compatible with local tests of
gravity. A possible way out, the chameleon effect, is also briefly
investigated.


title:
Probing the History of Cluster Assembly by Intracluster Planetary
  Nebulae

abstract:
  We describe the results and the current status of our program to search for
intracluster planetary nebulae (ICPNe) in the Virgo and the Coma clusters of
galaxies. For the Virgo cluster, ICPNe candidates were detected with narrow
band imaging combined with broad band imaging. The use of two narrow band
filters for H$\alpha$ and [O III] lines tuned for the cluster redshift enabled
us to detect secure ICPNe candidates. Kinematics of the detected ICPNe confirm
that the Virgo cluster is in a highly unrelaxed state. In order to detect ICPNe
in the Coma cluster, which is more than five times more distant than the Virgo
cluster, we devised a multi-slit imaging spectroscopy technique and
successfully detected 35 secure ICPNe candidates for the first time in this
cluster. We have found a hint that the Coma cluster is currently in the midst
of a subcluster merger.


title:
Collisions between tunable halo dimers: exploring an elementary
  four-body process with identical bosons

abstract:
  We study inelastic collisions in a pure, trapped sample of Feshbach molecules
made of bosonic cesium atoms in the quantum halo regime. We measure the
relaxation rate coefficient for decay to lower-lying molecular states and study
the dependence on scattering length and temperature. We identify a pronounced
loss minimum with varying scattering length along with a further suppression of
loss with decreasing temperature. Our observations provide insight into the
physics of a few-body quantum system that consists of four identical bosons at
large values of the two-body scattering length.


title: A Note on Ternary Sequences of Strings of 0 and 1

abstract:
  B. D. Acharya has conjectured that if $\bigl(A_i: i=1, 2, ...,
2^{|X|}-1\bigr)$ is a permutation of all nonempty subsets of a set $X$ with at
least two elements such that for each even positive integer $j<2^{|X|}-1$,
$A_{j-1}\triangle A_j\triangle A_{j+1}=\emptyset$, then $|X|=2$. In this
article, we show that if the cardinality of a set $X$ is more than four, then a
permutation as described above indeed exists.


title: Edge State Magnetism of Single Layer Graphene Nanostructures

abstract:
  We study edge state magnetism in graphene nanostructures using a mean field
theory of the Hubbard model. We investigate how the magnetism of the zigzag
edges of graphene is affected by the presence of other types of terminating
edges and defects. By a detailed study of both regular shapes, such as
polygonal nanodots and nanoribbons, and irregular shapes, we conclude that the
magnetism in zigzag edges is very robust. Our calculations show that the zigzag
edges that are longer than three to four repeat units are always magnetic,
irrespective of other edges, regular or irregular. We, therefore, clearly
demonstrate that the edge irregularities and defects of the bounding edges of
graphene nanostructures does not destroy the edge state magnetism.


title: On Central Automorphisms Fixing the Center Element-wise

abstract:
  Let $G$ be a finite $p$-group of nilpotency class 2. We find necessary and
sufficient conditions on $G$ such that each central automorphism of $G$ fixes
the center of $G$ element-wise.


title: Profinite homotopy theory

abstract:
  We construct a model structure on simplicial profinite sets such that the
homotopy groups carry a natural profinite structure. This yields a rigid
profinite completion functor for spaces and pro-spaces. One motivation is the
\'etale homotopy theory of schemes in which higher profinite \'etale homotopy
groups fit well with the \'etale fundamental group which is always profinite.
We show that the profinite \'etale topological realization functor is a good
object in several respects.


title: Accurate sampling using Langevin dynamics

abstract:
  We show how to derive a simple integrator for the Langevin equation and
illustrate how it is possible to check the accuracy of the obtained
distribution on the fly, using the concept of effective energy introduced in a
recent paper [J. Chem. Phys. 126, 014101 (2007)]. Our integrator leads to
correct sampling also in the difficult high-friction limit. We also show how
these ideas can be applied in practical simulations, using a Lennard-Jones
crystal as a paradigmatic case.


title:
GMRT Radio Halo Survey in galaxy clusters at z = 0.2 -- 0.4. II.The eBCS
  clusters and analysis of the complete sample

abstract:
  We present the results of the GMRT cluster radio halo survey. The main
purposes of our observational project are to measure which fraction of massive
galaxy clusters in the redshift range z=0.2--0.4 hosts a radio halo, and to
constrain the expectations of the particle re--acceleration model for the
origin of the non--thermal radio emission. We selected a complete sample of 50
clusters in the X-ray band from the REFLEX (27) and the eBCS (23) catalogues.
In this paper we present Giant Metrewave Radio Telescope (GMRT) observations at
610 MHz for all clusters still lacking high sensitivity radio information, i.e.
16 eBCS and 7 REFLEX clusters, thus completing the radio information for the
whole sample. The typical sensitivity in our images is in the range 1$\sigma
\sim 35-100 \mu$Jy b$^{-1}$. We found a radio halo in A697, a diffuse
peripheral source of unclear nature in A781, a core--halo source in Z7160, a
candidate radio halo in A1682 and ``suspect'' central emission in Z2661.
Including the literature information, a total of 10 clusters in the sample host
a radio halo. A very important result of our work is that 25 out of the 34
clusters observed with the GMRT do not host extended central emission at the
sensitivity level of our observations, and for 20 of them firm upper limits to
the radio power of a giant radio halo were derived. The GMRT Radio Halo Survey
shows that radio halos are not common, and our findings on the fraction of
giant radio halos in massive clusters are consistent with the statistical
expectations based on the re--acceleration model. Our results favour primary to
secondary electron models.


title: Unified formalism for non-autonomous mechanical systems

abstract:
  We present a unified geometric framework for describing both the Lagrangian
and Hamiltonian formalisms of regular and non-regular time-dependent mechanical
systems, which is based on the approach of Skinner and Rusk (1983). The
dynamical equations of motion and their compatibility and consistency are
carefully studied, making clear that all the characteristics of the Lagrangian
and the Hamiltonian formalisms are recovered in this formulation. As an
example, it is studied a semidiscretization of the nonlinear wave equation
proving the applicability of the proposed formalism.


title: Elastic and Proton Dynamics of the DNA

abstract:
  The subject of this report is the dynamics of elastic system in conjunction
with hydrogen bonds of the DNA. We draw attention to the draw-back of the
familiar rod model of the DNA, and make a case of constructing models that
could accommodate the intrinsic structure of the DNA. In this respect studying
the interplay among the elastic system and the protons of the DNA, is of
interest, for it could accommodate the inter-strand as well as the tunneling
modes of protons. Following this direction, we come to the conclusion that the
elastic-proton dynamics may have a bearing on biophysics of the DNA. The
phenomenon of point mutations is discussed within this framework.


title: Renormalized Thermal Entropy in Field Theory

abstract:
  Standard entropy calculations in quantum field theory, when applied to a
subsystem of definite volume, exhibit area-dependent UV divergences that make a
thermodynamic interpretation troublesome. In this paper we define a
renormalized entropy which is related with the Newton-Wigner position operator.
Accordingly, whenever we trace over a region of space, we trace away degrees of
freedom that are localized according to Newton-Wigner localization but not in
the usual sense. We consider a free scalar field in d+1 spacetime dimensions
prepared in a thermal state and we show that our entropy is free of divergences
and has a perfectly sound thermodynamic behavior. In the high temperature/big
volume limit our results agree with the standard QFT calculations once the
divergent contributions are subtracted from the latter. In the limit of low
temperature/small volume the entropy goes to zero but with a different
dependence on the temperature.


title: Self-affine Fractals Embedded in Spectra of Complex Networks

abstract:
  The scaling properties of spectra of real world complex networks are studied
by using the wavelet transform. It is found that the spectra of networks are
multifractal. According to the values of the long-range correlation exponent,
the Hust exponent $H$, the networks can be classified into three types, namely,
$H>0.5$, $H=0.5$ and $H<0.5$. All real world networks considered belong to the
class of $H \ge 0.5$, which may be explained by the hierarchical properties.


title: Bayes in the sky: Bayesian inference and model selection in cosmology

abstract:
  The application of Bayesian methods in cosmology and astrophysics has
flourished over the past decade, spurred by data sets of increasing size and
complexity. In many respects, Bayesian methods have proven to be vastly
superior to more traditional statistical tools, offering the advantage of
higher efficiency and of a consistent conceptual basis for dealing with the
problem of induction in the presence of uncertainty. This trend is likely to
continue in the future, when the way we collect, manipulate and analyse
observations and compare them with theoretical models will assume an even more
central role in cosmology.
  This review is an introduction to Bayesian methods in cosmology and
astrophysics and recent results in the field. I first present Bayesian
probability theory and its conceptual underpinnings, Bayes' Theorem and the
role of priors. I discuss the problem of parameter inference and its general
solution, along with numerical techniques such as Monte Carlo Markov Chain
methods. I then review the theory and application of Bayesian model comparison,
discussing the notions of Bayesian evidence and effective model complexity, and
how to compute and interpret those quantities. Recent developments in
cosmological parameter extraction and Bayesian cosmological model building are
summarized, highlighting the challenges that lie ahead.


title: Noncommutative oscillator, symmetry and Landau problem

abstract:
  Isotropic oscillator on a plane is discussed where both the coordinate and
momentum space are considered to be noncommutative. We also discuss the
symmetry properties of the oscillator for three separate cases when both the
noncommutative parameters \Theta and \bar{\Theta} satisfy specific relations.
We compare the Landau problem with the isotropic oscillator on noncommutative
space and obtain a relation between the two noncommutative parameters with the
magnetic field of the Landau problem.