title:
Near- and Far-Infrared Counterparts of Millimeter Dust Cores in the Vela
  Molecular Ridge Cloud D

abstract:
  The aim of this paper is to identify the young protostellar counterparts
associated to dust millimeter cores of the Vela Molecular Ridge Cloud D through
new IR observations (H_2 narrow-band at 2.12 micron and N broad band at 10.4
micron) along with an investigation performed on the existing IR catalogues.
The association of mm continuum emission with infrared sources from catalogues
(IRAS, MSX, 2MASS), JHK data from the literature and new observations, has been
established according to spatial coincidence, infrared colours and spectral
energy distributions. Only 7 out of 29 resolved mm cores (and 16 out of the 26
unresolved ones) do not exhibit signposts of star formation activity. The other
ones are clearly associated with: far-IR sources, H_2 jets or near-IR objects
showing a high intrinsic colour excess. The distribution of the spectral
indices pertaining to the associated sources is peaked at values typical of
Class I objects, while three objects are signalled as candidates Class 0
sources. We remark the high detection rate (30%) of H_2 jets driven by sources
located inside the mm-cores. They appear not driven by the most luminous
objects in the field, but rather by less luminous objects in young clusters,
testifying the co-existence of both low- and intermediate-mass star formation.
The presented results reliably describe the young population of VMR-D. However,
the statistical evaluation of activity vs inactivity of the investigated cores,
even in good agreement with results found for other star forming regions, seems
to reflect the limiting sensitivity of the available facilities rather than any
property intrinsic to the mm-condensations.


title:
High-precision covariant one-boson-exchange potentials for np scattering
  below 350 MeV

abstract:
  All realistic potential models for the two-nucleon interaction are to some
extent based on boson exchange. However, in order to achieve an essentially
perfect fit to the scattering data, characterized by a chi2/Ndata ~ 1, previous
potentials have abandoned a pure one boson-exchange mechanism (OBE). Using a
covariant theory, we have found a OBE potential that fits the 2006 world np
data below 350 MeV with a chi2/Ndata = 1.06 for 3788 data. Our potential has
fewer adjustable parameters than previous high-precision potentials, and also
reproduces the experimental triton binding energy without introducing
additional irreducible three-nucleon forces.


title: Pseudodifferential operators and weighted normed symbol spaces

abstract:
  In this work we study some general classes of pseudodifferential operators
whose symbols are defined in terms of phase space estimates.


title: Entwining Structures in Monoidal Catrgories

abstract:
  Interpreting entwining structures as special instances of J. Beck's
distributive law, the concept of entwining module can be generalized for the
setting of arbitrary monoidal category. In this paper, we use the distributive
law formalism to extend in this setting basic properties of entwining modules.


title:
CP Violation and Arrows of Time Evolution of a Neutral $K$ or $B$ Meson
  from an Incoherent to a Coherent State

abstract:
  We study the evolution of a neutral $K$ meson prepared as an incoherent equal
mixture of $K^0$ and $\bar{K^0}$. Denoting the density matrix by $\rho(t) =
{1/2} N(t) [\1 + \vec{\zeta}(t) \cdot \vec{\sigma} ] $, the norm of the state
$N(t)$ is found to decrease monotonically from one to zero, while the magnitude
of the Stokes vector $|\vec{\zeta}(t)|$ increases monotonically from zero to
one. This property qualifies these observables as arrows of time. Requiring
monotonic behaviour of $N(t)$ for arbitrary values of $\gamma_L, \gamma_S$ and
$\Delta m$ yields a bound on the CP-violating overlap $\delta =
\braket{K_L}{K_S}$, which is similar to, but weaker than, the known unitarity
bound. A similar requirement on $|\vec{\zeta}(t)|$ yields a new bound,
$\delta^2 < {1/2} (\frac{\Delta \gamma}{\Delta m}) \sinh (\frac{3\pi}{4}
\frac{\Delta \gamma}{\Delta m})$ which is particularly effective in limiting
the CP-violating overlap in the $B^0$-$\bar{B^0}$ system. We obtain the Stokes
parameter $\zeta_3(t)$ which shows how the average strangeness of the beam
evolves from zero to $\delta$. The evolution of the Stokes vector from
$|\vec{\zeta}| = 0$ to $|\vec{\zeta}| = 1$ has a resemblance to an order
parameter of a system undergoing spontaneous symmetry breaking.


title: Residual entropy in a model for the unfolding of single polymer chains

abstract:
  We study the unfolding of a single polymer chain due to an external force. We
use a simplified model which allows to perform all calculations in closed form
without assuming a Boltzmann-Gibbs form for the equilibrium distribution.
Temperature is then defined by calculating the Legendre transform of the
entropy under certain constraints. The application of the model is limited to
flexible polymers. It exhibits a gradual transition from compact globule to
rod. The boundary line between these two phases shows reentrant behavior. This
behavior is explained by the presence of residual entropy.


title:
Generalization of Einstein-Lovelock theory to higher order dilaton
  gravity

abstract:
  A higher order theory of dilaton gravity is constructed as a generalization
of the Einstein-Lovelock theory of pure gravity. Its Lagrangian contains terms
with higher powers of the Riemann tensor and of the first two derivatives of
the dilaton. Nevertheless, the resulting equations of motion are quasi-linear
in the second derivatives of the metric and of the dilaton. This property is
crucial for the existence of brane solutions in the thin wall limit. At each
order in derivatives the contribution to the Lagrangian is unique up to an
overall normalization. Relations between symmetries of this theory and the
O(d,d) symmetry of the string-inspired models are discussed.


title:
Fluctuations of the partial filling factors in competitive RSA from
  binary mixtures

abstract:
  Competitive random sequential adsorption on a line from a binary mix of
incident particles is studied using both an analytic recursive approach and
Monte Carlo simulations. We find a strong correlation between the small and the
large particle distributions so that while both partial contributions to the
fill factor fluctuate widely, the variance of the total fill factor remains
relatively small. The variances of partial contributions themselves are quite
different between the smaller and the larger particles, with the larger
particle distribution being more correlated. The disparity in fluctuations of
partial fill factors increases with the particle size ratio. The additional
variance in the partial contribution of smaller particle originates from the
fluctuations in the size of gaps between larger particles. We discuss the
implications of our results to semiconductor high-energy gamma detectors where
the detector energy resolution is controlled by correlations in the cascade
energy branching process.


title:
Sur les repr\'esentations du groupe fondamental d'une vari\'et\'e
  priv\'ee d'un diviseur \`a croisements normaux simples

abstract:
  Given a projective variety X over an algebraically closed field of
characteristic zero, we show that finite parabolic bundles along a fixed simple
normal crossings divisor D are in one to one correspondence with
representations of the \'etale fundamental group of X-D.


title:
Infrared High-Resolution Spectroscopy of Post-AGB Circumstellar Disks.
  I. HR 4049 - The Winnowing Flow Observed?

abstract:
  High-resolution infrared spectroscopy in the 2.3-4.6 micron region is
reported for the peculiar A supergiant, single-lined spectroscopic binary HR
4049. Lines from the CO fundamental and first overtone, OH fundamental, and
several H2O vibration-rotation transitions have been observed in the
near-infrared spectrum. The spectrum of HR 4049 appears principally in emission
through the 3 and 4.6 micron region and in absorption in the 2 micron region.
The 4.6 micron spectrum shows a rich 'forest' of emission lines. All the
spectral lines observed in the 2.3-4.6 micron spectrum are shown to be
circumbinary in origin. The presence of OH and H2O lines confirm the
oxygen-rich nature of the circumbinary gas which is in contrast to the
previously detected carbon-rich material. The emission and absorption line
profiles show that the circumbinary gas is located in a thin, rotating layer
near the dust disk. The properties of the dust and gas circumbinary disk and
the spectroscopic orbit yield masses for the individual stars, M_AI~0.58 Msolar
and M_MV~0.34 Msolar. Gas in the disk also has an outward flow with a velocity
of $\gtrsim$ 1 km/s. The severe depletion of refractory elements but near-solar
abundances of volatile elements observed in HR 4049 results from abundance
winnowing. The separation of the volatiles from the grains in the disk and the
subsequent accretion by the star are discussed. Contrary to prior reports, the
HR 4049 carbon and oxygen isotopic abundances are typical AGB values:
12C/13C=6^{+9}_{-4} and 16O/17O>200.


title: Tannakian Categories attached to abelian Varieties

abstract:
  Starting from certain perverse sheaves on an abelian variety, including the
intersection cohomology sheaves of curves and smooth ample divisors, we
construct a semisimple super-Tannakian category.


title:
On the Entropy Function and the Attractor Mechanism for Spherically
  Symmetric Extremal Black Holes

abstract:
  In this paper we elaborate on the relation between the entropy formula of
Wald and the "entropy function" method proposed by A. Sen. For spherically
symmetric extremal black holes, it is shown that the expression of extremal
black hole entropy given by A. Sen can be derived from the general entropy
definition of Wald, without help of the treatment of rescaling the AdS_2 part
of near horizon geometry of extremal black holes. In our procedure, we only
require that the surface gravity approaches to zero, and it is easy to
understand the Legendre transformation of f, the integration of Lagrangian
density on the horizon, with respect to the electric charges. Since the Noether
charge form can be defined in an "off-shell" form, we define a corresponding
entropy function, with which one can discuss the attractor mechanism for
extremal black holes with scalar fields.


title: Dynamical layer decoupling in a stripe-ordered, high T_c superconductor

abstract:
  In the stripe-ordered state of a strongly-correlated two-dimensional
electronic system, under a set of special circumstances, the superconducting
condensate, like the magnetic order, can occur at a non-zero wave-vector
corresponding to a spatial period double that of the charge order. In this
case, the Josephson coupling between near neighbor planes, especially in a
crystal with the special structure of La_{2-x}Ba_xCuO_4, vanishes identically.
We propose that this is the underlying cause of the dynamical decoupling of the
layers recently observed in transport measurements at x=1/8.


title:
Cooling and heating by adiabatic magnetization in the
  Ni$_{50}$Mn$_{34}$In$_{16}$ magnetic shape memory alloy

abstract:
  We report on measurements of the adiabatic temperature change in the inverse
magnetocaloric Ni$_{50}$Mn$_{34}$In$_{16}$ alloy. It is shown that this alloy
heats up with the application of a magnetic field around the Curie point due to
the conventional magnetocaloric effect. In contrast, the inverse magnetocaloric
effect associated with the martensitic transition results in the unusual
decrease of temperature by adiabatic magnetization. We also provide
magnetization and specific heat data which enable to compare the measured
temperature changes to the values indirectly computed from thermodynamic
relationships. Good agreement is obtained for the conventional effect at the
second-order paramagnetic-ferromagnetic phase transition. However, at the first
order structural transition the measured values at high fields are lower than
the computed ones. Irreversible thermodynamics arguments are given to show that
such a discrepancy is due to the irreversibility of the first-order martensitic
transition.


title: Giant Fluctuations of Coulomb Drag in a Bilayer System

abstract:
  We have observed reproducible fluctuations of the Coulomb drag, both as a
function of magnetic field and electron concentration, which are a
manifestation of quantum interference of electrons in the layers. At low
temperatures the fluctuations exceed the average drag, giving rise to random
changes of the sign of the drag. The fluctuations are found to be much larger
than previously expected, and we propose a model which explains their
enhancement by considering fluctuations of local electron properties.


title: Magnetic superelasticity and inverse magnetocaloric effect in Ni-Mn-In

abstract:
  Applying a magnetic field to a ferromagnetic Ni$_{50}$Mn$_{34}$In$_{16}$
alloy in the martensitic state induces a structural phase transition to the
austenitic state. This is accompanied by a strain which recovers on removing
the magnetic field giving the system a magnetically superelastic character. A
further property of this alloy is that it also shows the inverse magnetocaloric
effect. The magnetic superelasticity and the inverse magnetocaloric effect in
Ni-Mn-In and their association with the first order structural transition is
studied by magnetization, strain, and neutron diffraction studies under
magnetic field.


title: SN 2003du: 480 days in the Life of a Normal Type Ia Supernova

abstract:
  An extensive set of optical and NIR photometry and low-resolution spectra the
Type Ia supernova (SN Ia) 2003du was obtained using a number of facilities. The
observations started 13 days before B-band maximum light and continued for 480
days with exceptionally good time sampling. The optical photometry was
calibrated through the S-correction technique.
  The UBVRIJHK light curves and the color indices of SN 2003du closely resemble
those of normal SNe Ia. SN 2003du reached a B-band maximum of 13.49 (+/-0.02)
mag on JD2452766.38 (+/-0.5). We derive a B-band stretch parameter of 0.988
(+/-0.003), which corresponds to dM15=1.02 (+/-0.05), indicative of a SN Ia of
standard luminosity. The reddening in the host galaxy was estimated by three
methods, and was consistently found to be negligible. We estimate a distance
modulus of 32.79 (+/-0.15) mag to the host galaxy, UGC 9391. The peak UVOIR
bolometric luminosity of 1.35(+/-0.20) 10^43 erg/s and Arnett's rule implies
that M(Ni56)=0.68 (+/-0.14)M_sun of Ni56 was synthesized during the explosion.
Modeling of the UVOIR bolometric light curve also indicates M(Ni56) in the
range 0.6-0.8 M_sun. The spectral evolution of SN 2003du at both optical and
NIR wavelengths also closely resembles normal SNe Ia. In particular, the Si II
ratio at maximum R(Si II)=0.22 (+/-0.02) and the time evolution of the
blueshift velocities of the absorption line minima are typical. The pre-maximum
spectra of SN 2003du showed conspicuous high-velocity features in the Ca II H&K
doublet and infrared triplet, and possibly in Si II 6355, lines. We compare the
time evolution of the profiles of these lines with other well-observed SNe Ia
and we suggest that the peculiar pre-maximum evolution of Si II 6355 line in
many SNe Ia is due to the presence of two blended absorption components.


title: Outflow and Infall in a Sample of Massive Star Forming Regions

abstract:
  We present single pointing observations of SiO, HCO$^+$ and H$^{13}$CO$^+$
from the James Clerk Maxwell Telescope towards 23 massive star forming regions
previously known to contain molecular outflows and ultracompact HII regions. We
detected SiO towards 14 sources and suggest that the non-detections in the
other nine sources could be due to those outflows being older and without
ongoing shocks to replenish the SiO. We serendipitously detected SO$_2$ towards
17 sources in the same tuning as HCO$^+$. We detected HCO$^+$ towards all
sources, and suggest that it is tracing infall in nine cases. For seven infall
candidates, we estimate mass infall rates between 1$\times10^{-2}$ and
2$\times10^{-5}$ M$_{\odot}$ yr$^{-1}$. Seven sources show both SiO detections
(young outflows) and HCO$^+$ infall signatures. We also find that the abundance
of H$^{13}$CO$^+$ tends to increase along with the abundance of SiO in sources
for which we could determine abundances. We discuss these results with respect
to current theories of massive star formation via accretion. From this survey,
we suggest that perhaps both models of ionized accretion and halted accretion
may be important in describing the evolution of a massive protostar (or
protostars) beyond the formation of an HII region.


title:
Invariants of Welded Virtual Knots Via Crossed Module Invariants of
  Knotted Surfaces

abstract:
  We define an invariant of welded virtual knots from each finite crossed
module by considering crossed module invariants of ribbon knotted surfaces
which are naturally associated with them. We elucidate that the invariants
obtained are non trivial by calculating explicit examples. We define welded
virtual graphs and consider invariants of them defined in a similar way.


title: A Rational Approach to Resonance Saturation in large-Nc QCD

abstract:
  We point out that resonance saturation in QCD can be understood in the
large-Nc limit from the mathematical theory of Pade Approximants to meromorphic
functions. These approximants are rational functions which encompass any
saturation with a finite number of resonances as a particular example,
explaining several results which have appeared in the literature. We review the
main properties of Pade Approximants with the help of a toy model for the
<VV-AA> two-point correlator, paying particular attention to the relationship
among the Chiral Expansion, the Operator Product Expansion and the resonance
spectrum. In passing, we also comment on an old proposal made by Migdal in 1977
which has recently attracted much attention in the context of AdS/QCD models.
Finally, we apply the simplest Pade Approximant to the <VV-AA> correlator in
the real case of QCD. The general conclusion is that a rational approximant may
reliably describe a Green's function in the Euclidean, but the same is not true
in the Minkowski regime due to the appearance of unphysical poles and/or
residues.


title: Unification and Fermion Mass Structure

abstract:
  Grand Unified Theories predict relationships between the GUT-scale quark and
lepton masses. Using new data in the context of the MSSM, we update the values
and uncertainties of the masses and mixing angles for the three generations at
the GUT scale. We also update fits to hierarchical patterns in the GUT-scale
Yukawa matrices. The new data shows not all the classic GUT-scale mass
relationships remain in quantitative agreement at small to moderate tan beta.
However, at large tan beta, these discrepancies can be eliminated by finite,
tan beta-enhanced, radiative, threshold corrections if the gluino mass has the
opposite sign to the wino mass.


title: Cluster tilting for one-dimensional hypersurface singularities

abstract:
  In this article we study Cohen-Macaulay modules over one-dimensional
hypersurface singularities and the relationship with the representation theory
of associative algebras using methods of cluster tilting theory. We give a
criterion for existence of cluster tilting objects and their complete
description by homological methods, using higher almost split sequences and
results from birational geometry. We obtain a large class of 2-CY tilted
algebras which are finite dimensional symmetric and satisfy $\tau^2=\id$. In
particular, we compute 2-CY tilted algebras for simple and minimally elliptic
curve singularities.


title:
Gemini Mid-IR Polarimetry of NGC1068: Polarized Structures Around the
  Nucleus

abstract:
  We present diffraction limited, 10um imaging polarimetry data for the central
regions of the archetypal Seyfert AGN, NGC1068. The position angle of
polarization is consistent with three dominant polarizing mechanisms. We
identify three distinct regions of polarization: (a) north of the nucleus,
arising from aligned dust in the NLR, (b) south, east and west of the nucleus,
consistent with dust being channeled toward the central engine and (c) a
central minimum of polarization consistent with a compact (<22pc) torus. These
observations provide continuity between the geometrically and optically thick
torus and the host galaxy's nuclear environments. These images represent the
first published mid-IR polarimetry from an 8-m class telescope and illustrate
the potential of such observations.


title:
Coupling between magnetic ordering and structural instabilities in
  perovskite biferroics: A first-principles study

abstract:
  We use first-principles density functional theory-based calculations to
investigate structural instabilities in the high symmetry cubic perovskite
structure of rare-earth (R $=$ La, Y, Lu) and Bi-based biferroic chromites,
focusing on $\Gamma$ and $R$ point phonons of states with para-, ferro-, and
antiferromagnetic ordering. We find that (a) the structure with G-type
antiferromagnetic ordering is most stable, (b) the most dominant structural
instabilities in these oxides are the ones associated with rotations of oxygen
octahedra, and (c) structural instabilities involving changes in Cr-O-Cr bond
angle depend sensitively on the changes in magnetic ordering. The dependence of
structural instabilities on magnetic ordering can be understood in terms of how
super-exchange interactions depend on the Cr-O-Cr bond angles and Cr-O bond
lengths. We demonstrate how adequate buckling of Cr-O-Cr chains can favour
ferromagnetism. Born effective charges (BEC) calculated using the Berry phase
expression are found to be anomalously large for the A-cations, indicating
their chemical relevance to ferroelectric distortions.


title:
LNRF-velocity hump-induced oscillations of a Keplerian disc orbiting
  near-extreme Kerr black hole: A possible explanation of high-frequency QPOs
  in GRS 1915+105

abstract:
  At least four high-frequency quasiperiodic oscillations (QPOs) at frequencies
41Hz, 67Hz, 113Hz, and 167Hz were reported in a binary system GRS 1915+105
hosting near-extreme Kerr black hole with a dimensionless spin a>0.98. We use
the idea of oscillations induced by the hump of the orbital velocity profile
(related to locally non-rotating frames - LNRF) in discs orbiting near-extreme
Kerr black holes, which are characterized by a "humpy frequency" f_h, that
could excite the radial and vertical epicyclic oscillations with frequencies
f_r, f_v. Due to non-linear resonant phenomena the combinational frequencies
are allowed as well. Assuming mass M=14.8M_sun and spin a=0.9998 for the GRS
1915+105 Kerr black hole, the model predicts frequencies f_h=41Hz, f_r=67Hz,
(f_h+f_r)=108Hz, (f_v-f_r)=170Hz corresponding quite well to the observed ones.
For black-hole parameters being in good agreement with those given
observationally, the forced resonant phenomena in non-linear oscillations,
excited by the "hump-induced" oscillations in a Keplerian disc, can explain
high-frequency QPOs in GRS 1915+105 within the range of observational errors.


title: Compton thick AGN in the Suzaku era

abstract:
  Suzaku observations of two hard X-ray (> 10 keV) selected nearby Seyfert 2
galaxies are presented. Both sources were clearly detected with the PIN Hard
X-ray Detector up to several tens of keV, allowing for a fairly good
characterization of the broad band X-ray continuum. Both sources are heavily
obscured, one of which (NGC 5728) being Compton thick, while at lower energies
the shape and intensity of the scattered/reflected continuum is very different.
Strong iron Kalpha lines are detected in both sources. There are also hints for
the presence of a broad relativistic iron line in NGC 4992.


title:
Spin-dependence of Ce $4f$ hybridization in magnetically ordered
  systems: A spin-resolved photoemission study of Ce/Fe(110)

abstract:
  Spin- and angle-resolved resonant (Ce $4d\to4f$) photoemission spectra of a
monolayer Ce on Fe(110) reveal spin-dependent changes of the Fermi-level peak
intensities. That indicate a spin-dependence of $4f$ hybridization and, thus,
of $4f$ occupancy and local moment. The phenomenon is described in the
framework of the periodic Anderson model by $4f$ electron hopping into the
exchange split Fe 3d derived bands that form a spin-gap at the Fermi energy
around the $\bar{\Gamma}$ point of the surface Brillouin zone.


title: Two-way coupling of FENE dumbbells with a turbulent shear flow

abstract:
  We present numerical studies for finitely extensible nonlinear elastic (FENE)
dumbbells which are dispersed in a turbulent plane shear flow at moderate
Reynolds number. The polymer ensemble is described on the mesoscopic level by a
set of stochastic ordinary differential equations with Brownian noise. The
dynamics of the Newtonian solvent is determined by the Navier-Stokes equations.
Momentum transfer of the dumbbells with the solvent is implemented by an
additional volume forcing term in the Navier-Stokes equations, such that both
components of the resulting viscoelastic fluid are connected by a two-way
coupling. The dynamics of the dumbbells is given then by Newton's second law of
motion including small inertia effects. We investigate the dynamics of the flow
for different degrees of dumbbell elasticity and inertia, as given by
Weissenberg and Stokes numbers, respectively. For the parameters accessible in
our study, the magnitude of the feedback of the polymers on the macroscopic
properties of turbulence remains small as quantified by the global energy
budget and the Reynolds stresses. A reduction of the turbulent drag by up to
20% is observed for the larger particle inertia. The angular statistics of the
dumbbells shows an increasing alignment with the mean flow direction for both,
increasing elasticity and inertia. This goes in line with a growing asymmetry
of the probability density function of the transverse derivative of the
streamwise turbulent velocity component. We find that dumbbells get stretched
referentially in regions where vortex stretching or bi-axial strain dominate
the local dynamics and topology of the velocity gradient tensor.


title:
A Novel String Derived Z' With Stable Proton, Light-Neutrinos and
  R-parity violation

abstract:
  The Standard Model indicates the realization of grand unified structures in
nature, and can only be viewed as an effective theory below a higher energy
cutoff. While the renormalizable Standard Model forbids proton decay mediating
operators due to accidental global symmetries, many extensions of the Standard
Model introduce such dimension four, five and six operators. Furthermore,
quantum gravity effects are expected to induce proton instability, indicating
that the higher energy cutoff scale must be above 10^{16}GeV. Quasi-realistic
heterotic string models provide the arena to explore how perturbative quantum
gravity affects the particle physics phenomenology. An appealing explanation
for the proton longevity is provided by the existence of an Abelian gauge
symmetry that suppresses the proton decay mediating operators. Additionally,
such a low-scale U(1) symmetry should: allow the suppression of the left-handed
neutrino masses by a seesaw mechanism; allow fermion Yukawa couplings to the
electroweak Higgs doublets; be anomaly free; be family universal. These
requirements render the existence of such U(1) symmetries in quasi-realistic
heterotic string models highly non-trivial. We demonstrate the existence of a
U(1) symmetry that satisfies all of the above requirements in a class of
left-right symmetric heterotic string models in the free fermionic formulation.
The existence of the extra Z' in the energy range accessible to future
experiments is motivated by the requirement of adequate suppression of proton
decay mediation. We further show that while the extra U(1) forbids dimension
four baryon number violating operators it allows dimension four lepton number
violating operators and R-parity violation.


title: Complexity of Janet basis of a D-module

abstract:
  We prove a double-exponential upper bound on the degree and on the complexity
of constructing a Janet basis of a $D$-module. This generalizes a well known
bound on the complexity of a Gr\"obner basis of a module over the algebra of
polynomials. We would like to emphasize that the obtained bound can not be
immediately deduced from the commutative case.


title: Evidence for a merger of binary white dwarfs: the case of GD 362

abstract:
  GD 362 is a massive white dwarf with a spectrum suggesting a H-rich
atmosphere which also shows very high abundances of Ca, Mg, Fe and other
metals. However, for pure H-atmospheres the diffusion timescales are so short
that very extreme assumptions have to be made to account for the observed
abundances of metals. The most favored hypothesis is that the metals are
accreted from either a dusty disk or from an asteroid belt. Here we propose
that the envelope of GD 362 is dominated by He, which at these effective
temperatures is almost completely invisible in the spectrum. This assumption
strongly alleviates the problem, since the diffusion timescales are much larger
for He-dominated atmospheres. We also propose that the He-dominated atmosphere
of GD 362 is likely to be the result of the merger of a binary white dwarf.


title: Intersection local time for two independent fractional Brownian motions

abstract:
  We prove the existence of the intersection local time for two independent, d
-dimensional fractional Brownian motions with the same Hurst parameter H.
Assume d greater or equal to 2, then the intersection local time exists if and
only if Hd<2.


title: Lapse of transmission phase and electron molecules in quantum dots

abstract:
  The puzzling behavior of the transition phase through a quantum dot can be
understood in a natural way via a formation of the electron molecule in the
quantum dot. In this case the resonance tunneling takes place through the
quasi-stationary (doorway) state, which emerges when the number of electrons
occupying the dot reaches a certain ``critical'' value, $N_{cr}$. Our
estimation of this quantity agrees with the experimental data. The dependence
of $N_{cr}$ on the dot's size is predicted as well.


title:
Quantum-corrected black hole thermodynamics to all orders in the Planck
  length

abstract:
  We investigate the effects to all orders in the Planck length from a
generalized un- certainty principle (GUP) on black holes thermodynamics. We
calculate the corrected Hawking temperature, entropy, and examine in details
the Hawking evaporation process. As a result, the evaporation process is
accelerated and the evaporation end-point is a zero entropy, zero heat capacity
and finite non zero temperature black hole remnant (BHR). In particular we
obtain a drastic reduction of the decay time, in comparison with the results
obtained in the Hawking semi classical picture and with the GUP to leading
order in the Planck length.


title: Symmetry Breaking Study with Deformed Ensembles

abstract:
  A random matrix model to describe the coupling of m-fold symmetry in
constructed. The particular threefold case is used to analyze data on
eigenfrequencies of elastomechanical vibration of an anisotropic quartz block.
It is suggested that such experimental/theoretical study may supply powerful
means to discern intrinsic symmetries in physical systems.

categories: physics.data-an cond-mat.other nlin.CD nucl-th


title: The Measurement Calculus

abstract:
  Measurement-based quantum computation has emerged from the physics community
as a new approach to quantum computation where the notion of measurement is the
main driving force of computation. This is in contrast with the more
traditional circuit model which is based on unitary operations. Among
measurement-based quantum computation methods, the recently introduced one-way
quantum computer stands out as fundamental.
  We develop a rigorous mathematical model underlying the one-way quantum
computer and present a concrete syntax and operational semantics for programs,
which we call patterns, and an algebra of these patterns derived from a
denotational semantics. More importantly, we present a calculus for reasoning
locally and compositionally about these patterns.
  We present a rewrite theory and prove a general standardization theorem which
allows all patterns to be put in a semantically equivalent standard form.
Standardization has far-reaching consequences: a new physical architecture
based on performing all the entanglement in the beginning, parallelization by
exposing the dependency structure of measurements and expressiveness theorems.
  Furthermore we formalize several other measurement-based models:
Teleportation, Phase and Pauli models and present compositional embeddings of
them into and from the one-way model. This allows us to transfer all the theory
we develop for the one-way model to these models. This shows that the framework
we have developed has a general impact on measurement-based computation and is
not just particular to the one-way quantum computer.


title:
Aharonov-Bohm oscillations in the presence of strong spin-orbit
  interactions

abstract:
  We have measured highly visible Aharonov-Bohm (AB) oscillations in a ring
structure defined by local anodic oxidation on a p-type GaAs heterostructure
with strong spin-orbit interactions. Clear beating patterns observed in the raw
data can be interpreted in terms of a spin geometric phase. Besides h/e
oscillations, we resolve the contributions from the second harmonic of AB
oscillations and also find a beating in these h/2e oscillations. A resistance
minimum at B=0T, present in all gate configurations, is the signature of
destructive interference of the spins propagating along time-reversed paths.


title: Radio and X-ray nebulae associated with PSR J1509-5850

abstract:
  We have discovered a long radio trail at 843 MHz which is apparently
associated with middle age pulsar PSR J1509-5850. The radio trail has a length
of ~7 arcmin. In X-rays, Chandra observations of PSR J1509-5850 reveal an
associated X-ray trail which extends in the same orientation as the radio
trail. Moreover, two clumpy structures are observed along the radio trail. The
larger one is proposed to be the supernova remnant (SNR) candidate MSC
319.9-0.7. Faint X-ray enhancement at the position of the SNR candidate is
found in the Chandra data.


title:
Branching fraction and charge asymmetry measurements in B to J/psi pi pi
  decays

abstract:
  We study the decays B0 to J/psi pi+pi- and B+ to J/psi pi+pi0, including
intermediate resonances, using a sample of 382 million BBbar pairs recorded by
the BaBar detector at the PEP-II e+e- B factory. We measure the branching
fractions B(B0 ->J/psi rho0) = (2.7 +/- 0.3 +/- 0.17) x 10-5 and B(B+ ->J/psi
rho+) = (5.0 +/- 0.7 +/-0.31) x 10-5.
  We also set the following upper limits at the 90% confidence level: B(B0 ->
J/psi pi+ \pi- non-resonant) < 1.2 x 10-5, B(B0 -> J/psi f_2(1270)) < 4.6 x
10-6, and B(B+ -> J/psi pi+ pi0 non-resonant) < 4.4 x 10-6. We measure the
charge asymmetry in charged B decays to J/psi rho to be -0.11 +/- 0.12 +/-
0.08.


title: Text Line Segmentation of Historical Documents: a Survey

abstract:
  There is a huge amount of historical documents in libraries and in various
National Archives that have not been exploited electronically. Although
automatic reading of complete pages remains, in most cases, a long-term
objective, tasks such as word spotting, text/image alignment, authentication
and extraction of specific fields are in use today. For all these tasks, a
major step is document segmentation into text lines. Because of the low quality
and the complexity of these documents (background noise, artifacts due to
aging, interfering lines),automatic text line segmentation remains an open
research field. The objective of this paper is to present a survey of existing
methods, developed during the last decade, and dedicated to documents of
historical interest.


title:
On the interpretation of muon-spin-rotation experiments in the mixed
  state of type-II superconductors

abstract:
  We argue that claims about magnetic field dependence of the magnetic field
penetration depth lambda, which were made on the basis of moun-spin-rotation
studies of some superconductors, originate from insufficient accuracy of
theoretical models employed for the data analysis. We also reanalyze some of
already published experimental data and demonstrate that numerical calculations
of Brandt [E.H. Brandt, Phys. Rev. B 68, 54506 (2003)] may serve as a reliable
and powerful tool for the analysis of the data collected in experiments with
conventional superconductors. Furthermore, one can use this approach in order
to distinguish between conventional and unconventional superconductors. It is
unfortunate that these calculations have practically never been employed for
such analyses.


title: Phase Transitions in the Coloring of Random Graphs

abstract:
  We consider the problem of coloring the vertices of a large sparse random
graph with a given number of colors so that no adjacent vertices have the same
color. Using the cavity method, we present a detailed and systematic analytical
study of the space of proper colorings (solutions).
  We show that for a fixed number of colors and as the average vertex degree
(number of constraints) increases, the set of solutions undergoes several phase
transitions similar to those observed in the mean field theory of glasses.
First, at the clustering transition, the entropically dominant part of the
phase space decomposes into an exponential number of pure states so that beyond
this transition a uniform sampling of solutions becomes hard. Afterward, the
space of solutions condenses over a finite number of the largest states and
consequently the total entropy of solutions becomes smaller than the annealed
one. Another transition takes place when in all the entropically dominant
states a finite fraction of nodes freezes so that each of these nodes is
allowed a single color in all the solutions inside the state. Eventually, above
the coloring threshold, no more solutions are available. We compute all the
critical connectivities for Erdos-Renyi and regular random graphs and determine
their asymptotic values for large number of colors.
  Finally, we discuss the algorithmic consequences of our findings. We argue
that the onset of computational hardness is not associated with the clustering
transition and we suggest instead that the freezing transition might be the
relevant phenomenon. We also discuss the performance of a simple local Walk-COL
algorithm and of the belief propagation algorithm in the light of our results.


title: Core-Corona Separation in Ultra-Relativistic Heavy Ion Collisions

abstract:
  Simple geometrical considerations show that the collision zone in high energy
nuclear collisions may be divided into a central part (``core''), with high
energy densities, and a peripheral part (``corona''), with smaller energy
densities, more like in pp or pA collisions. We present calculations which
allow to separate these two contributions, and which show that the corona
contribution is quite small (but not negligible) for central collisions, but
gets increasingly important with decreasing centrality. We will discuss
consequences concerning results obtained in heavy ion collisions at the
Relativistic Heavy Ion Collider (RHIC) and the Super Proton Synchrotron (SPS).


title: Numerical Evaluation of Six-Photon Amplitudes

abstract:
  We apply the recently proposed amplitude reduction at the integrand level
method, to the computation of the scattering process 2 photons -> 4 photons,
including the case of a massive fermion loop. We also present several
improvements of the method, including a general strategy to reconstruct the
rational part of any one-loop amplitude and the treatment of vanishing
Gram-determinants.


title:
Dynamics of shear homeomorphisms of tori and the Bestvina-Handel
  algorithm

abstract:
  Sharkovskii proved that the existence of a periodic orbit in a
one-dimensional dynamical system implies existence of infinitely many periodic
orbits. We obtain an analog of Sharkovskii's theorem for periodic orbits of
shear homeomorphisms of the torus. This is done by obtaining a dynamical order
relation on the set of simple orbits and simple pairs. We then use this order
relation for a global analysis for a quantum chaotic physical system called the
kicked accelerated particle.


title: Coniveau over $p$-adic fields and points over finite fields

abstract:
  If the $\ell$-adic cohomology of a projective smooth variety, defined over a
$\frak{p}$-adic field $K$ with finite residue field $k$, is supported in
codimension $\ge 1$, then any model over the ring of integers of $K$ has a
$k$-rational point. This slightly improves our earlier result math/0405318: we
needed there the model to be regular (but then our result was more general: we
obtained a congruence for the number of points, and $K$ could be local of
characteristic $p>0$).


title: Parametric Learning and Monte Carlo Optimization

abstract:
  This paper uncovers and explores the close relationship between Monte Carlo
Optimization of a parametrized integral (MCO), Parametric machine-Learning
(PL), and `blackbox' or `oracle'-based optimization (BO). We make four
contributions. First, we prove that MCO is mathematically identical to a broad
class of PL problems. This identity potentially provides a new application
domain for all broadly applicable PL techniques: MCO. Second, we introduce
immediate sampling, a new version of the Probability Collectives (PC) algorithm
for blackbox optimization. Immediate sampling transforms the original BO
problem into an MCO problem. Accordingly, by combining these first two
contributions, we can apply all PL techniques to BO. In our third contribution
we validate this way of improving BO by demonstrating that cross-validation and
bagging improve immediate sampling. Finally, conventional MC and MCO procedures
ignore the relationship between the sample point locations and the associated
values of the integrand; only the values of the integrand at those locations
are considered. We demonstrate that one can exploit the sample location
information using PL techniques, for example by forming a fit of the sample
locations to the associated values of the integrand. This provides an
additional way to apply PL techniques to improve MCO.


title:
On the Structure and Properties of Differentially Rotating Main-Sequence
  Stars in the 1-2 M_sun Range

abstract:
  We conduct a systematic examination of the properties of models for
chemically homogeneous, differentially rotating, main-sequence stars of mass
1-2 M_sun. The models were constructed using a code based on a reformulation of
the self-consistent field method of computing the equilibrium stellar structure
for a specified conservative internal rotation law. [abridged] Relative to
nonrotating stars of the same mass, these models all have reduced luminosities
and effective temperatures, and flattened photospheric shapes (i.e., decreased
polar radii) with equatorial radii that can be larger or smaller, depending on
the degree of differential rotation. For a fixed ratio of the axial rotation
rate to the surface equatorial rotation rate, increasingly rapid rotation
generally deepens convective envelopes, shrinks convective cores, and can lead
to the presence of a convective core (envelope) in a 1 M_sun (2 M_sun) model, a
feature that is absent in a nonrotating star of the same mass. The positions of
differentially rotating models for a given mass M in the H-R diagram can be
shifted in such a way as to approximate the nonrotating ZAMS over ranges in
luminosity and effective temperature that correspond to a mass interval between
M and about 0.7 M. We briefly note a few of the implications of these results,
including (i) possible ambiguities arising from similarities between the
properties of rotating and nonrotating models of different masses, (ii) a
reduced radiative luminosity for a young, rapidly rotating Sun, (iii) the
nuclear destruction of lithium and other light metallic species in the layers
beneath an outer convective envelope, and (iv), the excitation of solar-like
oscillations and the operation of a solar-like hydromagnetic dynamo in some
1.5-2 M_sun stars.


title: SDSS J102146.44+234926.3: New WZ Sge-type dwarf nova

abstract:
  We report CCD photometry and spectroscopy during 2006 outburst of the dwarf
nova SDSS J102146.44+234926.3 (SDSS J1021). The photographic plates from the
MAO, SAI and CrAO plate archives, which cover the position of the SDSS J1021,
were inspected for the presence of previous outbursts. We also present the
BVRcIc photometric calibration of 52 stars in SDSS J1021 vicinity, which have
V-magnitude in the range of 11.21-17.23m and can serve as comparison stars. The
large amplitude of the SDSS J1021 outburst of 7m, superhumps with a period
below the ''period gap'', rebrightening during the declining stage of
superoutburst, rarity of outbursts and obtained spectrum allow to classify this
object as a WZ Sge type dwarf nova.


title: Discrete phase space and minimum-uncertainty states

abstract:
  The quantum state of a system of qubits can be represented by a Wigner
function on a discrete phase space, each axis of the phase space taking values
in a finite field. Within this framework, we show that one can make sense of
the notion of a "rotationally invariant state" of any collection of qubits, and
that any such state is, in a well defined sense, a state of minimum
uncertainty.


title: Turbulent Mixing in the Surface Layers of Accreting Neutron Stars

abstract:
  During accretion a neutron star (NS) is spun up as angular momentum is
transported through its surface layers. We study the resulting differentially
rotating profile, focusing on the impact this has for type I X-ray bursts. The
predominant viscosity is likely provided by the Tayler-Spruit dynamo. The
radial and azimuthal magnetic field components have strengths of ~10^5 G and
~10^10 G, respectively. This leads to nearly uniform rotation at the depths of
interest for X-ray bursts. A remaining small shear transmits the accreted
angular momentum inward to the NS interior. Though this shear gives little
viscous heating, it can trigger turbulent mixing. Detailed simulations will be
required to fully understand the consequences of mixing, but our models
illustrate some general features. Mixing has the greatest impact when the
buoyancy at the compositional discontinuity between accreted matter and ashes
is overcome. This occurs at high accretion rates, at low spin frequencies, or
may depend on the ashes from the previous burst. We then find two new regimes
of burning. The first is ignition in a layer containing a mixture of heavier
elements from the ashes. If ignition occurs at the base of the mixed layer,
recurrence times as short as ~5-30 minutes are possible. This may explain the
short recurrence time of some bursts, but incomplete burning is still needed to
explain these bursts' energetics. When mixing is sufficiently strong, a second
regime is found where accreted helium mixes deep enough to burn stably,
quenching X-ray bursts. We speculate that the observed change in X-ray burst
properties near one-tenth the Eddington accretion rate is from this mechanism.
The carbon-rich material produced by stable helium burning would be important
for triggering and fueling superbursts. (abridged)


title:
Wide-bandwidth, tunable, multiple-pulse-width optical delays using slow
  light in cesium vapor

abstract:
  We demonstrate an all-optical delay line in hot cesium vapor that tunably
delays 275 ps input pulses up to 6.8 ns and 740 input ps pulses up to 59 ns
(group index of approximately 200) with little pulse distortion. The delay is
made tunable with a fast reconfiguration time (hundreds of ns) by optically
pumping out of the atomic ground states.


title: Controllable Quantum Switchboard

abstract:
  All quantum information processes inevitably requires the explicit state
preparation of an entangled state. Here we present the construction of a
quantum switchboard which can act both as an optimal quantum cloning machine
and a quantum demultiplexer based on the preparation of a four-qubit state.


title: The Galactic Center

abstract:
  In the past decade high resolution measurements in the infrared employing
adaptive optics imaging on 10m telescopes have allowed determining the three
dimensional orbits stars within ten light hours of the compact radio source at
the center of the Milky Way. These observations show the presence of a three
million solar mass black hole in Sagittarius A* beyond any reasonable doubt.
The Galactic Center thus constitutes the best astrophysical evidence for the
existence of black holes which have long been postulated, and is also an ideal
`lab' for studying the physics in the vicinity of such an object. Remarkably,
young massive stars are present there and probably have formed in the innermost
stellar cusp. Variable infrared and X-ray emission from Sagittarius A* are a
new probe of the physical processes and space-time curvature just outside the
event horizon.


title:
A geometric proof that $e$ is irrational and a new measure of its
  irrationality

abstract:
  We give a simple geometric proof that $e$ is irrational, using a construction
of a nested sequence of closed intervals with intersection $e$. The proof leads
to a new measure of irrationality for $e$: if $p$ and $q$ are integers with $q
> 1$, then $|e - p/q| > 1/(S(q)+1)!$, where $S(q)$ is the smallest positive
integer such that $S(q)!$ is a multiple of $q$. We relate this measure for $e$
to a known one and to the greatest prime factor of an integer. We make two
conjectures and recall a theorem of Cantor that can be proved by a similar
construction.


title: Scanning tunnelling microscopy for ultracold atoms

abstract:
  We propose a novel experimental probe for cold atomic gases analogous to the
scanning tunnelling microscope (STM) in condensed matter. This probe uses the
coherent coupling of a single particle to the system. Depending on the
measurement sequence, our probe allows to either obtain the \emph{local}
density, with a resolution on the nanometer scale, or the single particle
correlation function in real time. We discuss applications of this scheme to
the various possible phases for a two dimensional Hubbard system of fermions in
an optical lattice.


title:
Center Manifold and Lie Symmetry Calculations on a Quasi-chemical Model
  for Growth-death Kinetics in Food

abstract:
  Food scientists at the U.S. Army's Natick Solider Center have developed a
model for the lifecyle of the bacteria Staphylococcus aureus in intermediate
moisture bread. In this article, we study this model using dynamical systems
and Lie symmetry methods. We calculate center manifolds and Lie symmetries for
different cases of parameter values and compare our results to those of the
food scientists.


title:
Absence of commensurate ordering at the polarization flop transition in
  multiferroic DyMnO3

abstract:
  Ferroelectric spiral magnets DyMnO3 and TbMnO3 show similar behavior of
electric polarization in applied magnetic fields. Studies of the field
dependence of lattice modulations on the contrary show a completely different
picture. Whereas in TbMnO3 the polarization flop from P||c to P||a is
accompanied by a sudden change from incommensurate to commensurate wave vector
modulation, in DyMnO3 the wave vector varies continuously through the flop
transition. This smooth behavior may be related to the giant magnetocapacitive
effect observed in DyMnO3.


title:
Study of a finite volume - finite element scheme for a nuclear transport
  model

abstract:
  We consider a problem of nuclear waste contamination. It takes into account
the thermal effects. The temperature and the contaminant's concentration
fulfill convection-diffusion-reaction equations. The velocity and the pressure
in the flow satisfy the Darcy equation, with a viscosity depending on both
concentration and temperature. The equations are nonlinear and strongly
coupled. Using both finite volume and nonconforming finite element methods, we
introduce a scheme adapted to this problem. We prove the stability and
convergence of this scheme and give some error estimates.


title: Realizable Hamiltonians for Universal Adiabatic Quantum Computers

abstract:
  It has been established that local lattice spin Hamiltonians can be used for
universal adiabatic quantum computation. However, the 2-local model
Hamiltonians used in these proofs are general and hence do not limit the types
of interactions required between spins. To address this concern, the present
paper provides two simple model Hamiltonians that are of practical interest to
experimentalists working towards the realization of a universal adiabatic
quantum computer. The model Hamiltonians presented are the simplest known
QMA-complete 2-local Hamiltonians. The 2-local Ising model with 1-local
transverse field which has been realized using an array of technologies, is
perhaps the simplest quantum spin model but is unlikely to be universal for
adiabatic quantum computation. We demonstrate that this model can be rendered
universal and QMA-complete by adding a tunable 2-local transverse XX coupling.
We also show the universality and QMA-completeness of spin models with only
1-local Z and X fields and 2-local ZX interactions.


title:
Quantitative size-dependent structure and strain determination of CdSe
  nanoparticles using atomic pair distribution function analysis

abstract:
  The size-dependent structure of CdSe nanoparticles, with diameters ranging
from 2 to 4 nm, has been studied using the atomic pair distribution function
(PDF) method. The core structure of the measured CdSe nanoparticles can be
described in terms of the wurtzite atomic structure with extensive stacking
faults. The density of faults in the nanoparticles ~50% . The diameter of the
core region was extracted directly from the PDF data and is in good agreement
with the diameter obtained from standard characterization methods suggesting
that there is little surface amorphous region. A compressive strain was
measured in the Cd-Se bond length that increases with decreasing particle size
being 0.5% with respect to bulk CdSe for the 2 nm diameter particles. This
study demonstrates the size-dependent quantitative structural information that
can be obtained even from very small nanoparticles using the PDF approach.


title: Brane-world Quantum Gravity

abstract:
  The Arnowitt-Deser-Misner canonical formulation of general relativity is
extended to the covariant brane-world theory in arbitrary dimensions. The
exclusive probing of the extra dimensions makes a substantial difference,
allowing for the construction of a non-constrained canonical theory. The
quantum states of the brane-world geometry are defined by the
Tomonaga-Schwinger equation, whose integrability conditions are determined by
the classical perturbations of submanifolds contained in the Nash's
differentiable embedding theorem. In principle, quantum brane-world theory can
be tested by current experiments in astrophysics and by near future laboratory
experiments at Tev energy. The implications to the black-hole information loss
problem, to the accelerating cosmology, and to a quantum mathematical theory of
four-sub manifolds are briefly commented.


title: Isospin diffusion in thermal AdS/CFT with flavor

abstract:
  We study the gauge/gravity dual of a finite temperature field theory at
finite isospin chemical potential by considering a probe of two coincident
D7-branes embedded in the AdS-Schwarzschild black hole background. The isospin
chemical potential is obtained by giving a vev to the time component of the
non-Abelian gauge field on the brane. The fluctuations of the non-Abelian gauge
field on the brane are dual to the SU(2) flavor current in the field theory.
For the embedding corresponding to vanishing quark mass, we calculate all Green
functions corresponding to the components of the flavor current correlator. We
discuss the physical properties of these Green functions, which go beyond
linear response theory. In particular, we show that the isospin chemical
potential leads to a frequency-dependent isospin diffusion coefficient.


title: Projective Hilbert space structures at exceptional points

abstract:
  A non-Hermitian complex symmetric 2x2 matrix toy model is used to study
projective Hilbert space structures in the vicinity of exceptional points
(EPs). The bi-orthogonal eigenvectors of a diagonalizable matrix are
Puiseux-expanded in terms of the root vectors at the EP. It is shown that the
apparent contradiction between the two incompatible normalization conditions
with finite and singular behavior in the EP-limit can be resolved by
projectively extending the original Hilbert space. The complementary
normalization conditions correspond then to two different affine charts of this
enlarged projective Hilbert space. Geometric phase and phase jump behavior are
analyzed and the usefulness of the phase rigidity as measure for the distance
to EP configurations is demonstrated. Finally, EP-related aspects of
PT-symmetrically extended Quantum Mechanics are discussed and a conjecture
concerning the quantum brachistochrone problem is formulated.


title: Excitation of the dissipationless Higgs mode in a fermionic condensate

abstract:
  The amplitude mode of a fermionic superfluid, analogous to the Higgs Boson,
becomes undamped in the strong coupling regime when its frequency is pushed
inside the BCS energy gap. We argue that this is the case in cold gases due to
the energy dispersion and nonlocality of the pairing interaction, and propose
to use the Feshbach resonance regime for parametric excitation of this mode.
The results presented for the BCS pairing dynamics indicate that even weak
dispersion suppresses dephasing and gives rise to persistent oscillations. The
frequency of oscillations extracted from our simulation of the BCS dynamics
agrees with the prediction of the many-body theory.


title: Two characterizations of crooked functions

abstract:
  We give two characterizations of crooked functions: one based on the minimum
distance of a Preparata-like code, and the other based on the
distance-regularity of a crooked graph.


title:
A Disciplined Approach to Adopting Agile Practices: The Agile Adoption
  Framework

abstract:
  Many organizations aspire to adopt agile processes to take advantage of the
numerous benefits that it offers to an organization. Those benefits include,
but are not limited to, quicker return on investment, better software quality,
and higher customer satisfaction. To date however, there is no structured
process (at least in the public domain) that guides organizations in adopting
agile practices. To address this problem we present the Agile Adoption
Framework. The framework consists of two components: an agile measurement
index, and a 4-Stage process, that together guide and assist the agile adoption
efforts of organizations. More specifically, the agile measurement index is
used to identify the agile potential of projects and organizations. The 4-Stage
process, on the other hand, helps determine (a) whether or not organizations
are ready for agile adoption, and (b) guided by their potential, what set of
agile practices can and should be introduced.


title:
Electronic structure of the noncentrosymmetric superconductor
  Mg10Ir19B16

abstract:
  Electronic structure of a novel superconducting noncentrosymmetric compound
Mg10Ir19B16 was calculated using the Korringa-Kohn-Rostoker method. Electronic
part of the electron-phonon coupling constant, McMillan-Hopfield parameters,
were calculated using the rigid-muffin-tin approximation (RMTA). The magnitude
of the electron-phonon coupling constant, analysing atomic contributions, is
discussed. Our results show, that superconductivity in Mg10Ir19B16 is
presumably mediated by electron-phonon interaction.


title: Prospects of using simulations to study the photospheres of brown dwarfs

abstract:
  We discuss prospects of using multi-dimensional time-dependent simulations to
study the atmospheres of brown dwarfs and extrasolar giant planets, including
the processes of convection, radiation, dust formation, and rotation. We argue
that reasonably realistic simulations are feasible, however, separated into two
classes of local and global models. Numerical challenges are related to
potentially large dynamic ranges, and the treatment of scattering of radiation
in multi-D geometries.


title:
The exceptionally extended flaring activity in the X-ray afterglow of
  GRB 050730 observed with Swift and XMM-Newton

abstract:
  We present the results of a detailed spectral and temporal analysis of Swift
and XMM-Newton observations of the high redshift (z=3.969) GRB 050730. The
X-ray afterglow of GRB 050730 was found to decline with time with superimposed
intense flaring activity that extended over more than two orders of magnitude
in time. Seven distinct re-brightening events starting from 236 s up to 41.2 ks
after the burst were observed. The underlying decay of the afterglow was well
described by a double broken power-law model with breaks at t_1= 237 +/- 20 s
and t_2 = 10.1 (-2.2) (+4.6) ks. The temporal decay slopes before, between and
after these breaks were alpha_1 = 2.1 +/- 0.3, alpha_2 = 0.44 (-0.08) (+0.14)
and alpha_3 = 2.40 (+0.07) (-0.09), respectively. The spectrum of the X-ray
afterglow was well described by a photoelectrically absorbed power-law with an
absorbing column density N_H=(1.28 +/- 0.26) 10^22 cm^-2 in the host galaxy.
Strong X-ray spectral evolution during the flaring activity was present. In the
majority of the flares (6/7) the ratio Delta_t/t_p between the duration of the
event and the time when the flare peaks was nearly constant and about 0.6-0.7.
We showed that the observed spectral and temporal properties of the first three
flares are consistent with being due both to high-latitude emission, as
expected if the flares were produced by late internal shocks, or to refreshed
shocks, i.e. late time energy injections into the main afterglow shock by slow
moving shells ejected from the central engine during the prompt phase. The
event fully satisfies the E_p-E_iso Amati relation while is not consistent with
the E_p-E_jet Ghirlanda relation.


title:
The obscured quasar population from optical, mid-infrared, and X-ray
  surveys

abstract:
  Over the last few years, optical, mid-infrared and X-ray surveys have brought
to light a significant number of candidate obscured AGN and, among them, many
Type 2 quasars, the long-sought after "big cousins'' of local Seyfert 2
galaxies. However, despite the large amount of multi-wavelength data currently
available, a proper census and a panchromatic view of the obscured AGN/quasar
population are still missing, mainly due to observational limitations. Here we
provide a review of recent results on the identification of obscured AGN,
focusing primarily on the population of Type 2 quasars selected in the optical
band from the Sloan Digital Sky Survey.


title: The Realm of the First Quasars in the Universe: the X-ray View

abstract:
  We review the X-ray studies of the highest redshift quasars, focusing on the
results obtained with Chandra and XMM-Newton. Overall, the X-ray and broad-band
properties of z>4 quasars and local quasars are similar, suggesting that the
small-scale X-ray emission regions of AGN are insensitive to the significant
changes occurring at z=0-6.


title:
The obscured X-ray source population in the HELLAS2XMM survey: the
  Spitzer view

abstract:
  Recent X-ray surveys have provided a large number of high-luminosity,
obscured Active Galactic Nuclei (AGN), the so-called Type 2 quasars. Despite
the large amount of multi-wavelength supporting data, the main parameters
related to the black holes harbored in such AGN are still poorly known. Here we
present the results obtained for a sample of eight Type 2 quasars in the
redshift range 0.9-2.1 selected from the HELLAS2XMM survey, for which we used
Ks-band, Spitzer IRAC and MIPS data at 24 micron to estimate bolometric
corrections, black hole masses, and Eddington ratios.


title: IRAS 18317-0757: A Cluster of Embedded Massive Stars and Protostars

abstract:
  We present high-resolution, multiwavelength continuum and molecular-line
images of the massive star forming region IRAS 18317-0757. The IR through mm
spectral energy distribution can be approximated by a two-temperature model (25
and 63 K) with a total luminosity of approximately log(L/Lsun)=5.2. Previous
submm imaging resolved this region into a cluster of 5 dust cores, one of which
is associated with the UCHII region G23.96+0.15, and another with an H2O maser.
In our new 2.7 mm continuum image, only the UCHII region is detected, with
total flux and morphology in good agreement with the free-free emission in VLA
cm-wave maps. For the other four objects, the nondetections at 2.7 mm and in
the MSX mid-IR bands are consistent with cool dust emission with a temperature
of 13-40K and luminosity of 1000-40000 Lsun. By combining single-dish and
interferometric data, we have identified over two dozen virialized C18O cores
in this region that contain ~40% of the total molecular gas mass present. While
the overall extent of the C18O and dust emission is similar, the emission peaks
do not correlate well in detail. At least 11 of the 123 stars identified by
2MASS in this region are likely to be within the star-forming cluster. Two
stars (both associated with the UCHII region) were previously identified as O
stars via IR spectroscopy. Most of the rest of the reddened stars have no
obvious correlation with the C18O cores or the dust cores. In summary, our
observations indicate that considerable fragmentation of the molecular cloud
has taken place during the time required for the UCHII region to form and the O
stars to become detectable at IR wavelengths. Additional star formation appears
to be ongoing on the periphery of the central region, where up to four B-type
(proto)stars have formed among a substantial number of C18O molecular cores.


title: Photometry of the SW Sex-type nova-like BH Lyncis in high state

abstract:
  Aims: We present a photometric study of the deeply eclipsing SW Sex-type
nova-like cataclysmic variable star BH Lyn
  Methods: Time-resolved V-band CCD photometry was obtained for seven nights
between 1999 and 2004.
  Results: We determined 11 new eclipse timings of BH Lyn and derived a refined
orbital ephemeris with an orbital period of 0.155875577(14) day. During the
observations, BH Lyn was in high-state with V~15.5 mag. The star presents ~1.5
mag deep eclipses with mean full-width at half-flux of 0.0683(+/-0.0054)P_orb.
  The eclipse shape is highly variable, even changing form cycle to cycle. This
is most likely due to accretion disc surface brightness distribution
variations, most probably caused by strong flickering. Time-dependent accretion
disc self-occultation or variations of the hot spot(s) intensity are also
possible explanations. Negative superhumps with period of ~0.145 day are
detected in two long runs in 2000. A possible connection between SW Sex and
negative superhump phenomena through the presence of tilted accretion disc is
discussed, and a way to observationally test this is suggested.


title:
General Doppler Shift Equation and the Possibility of Systematic Error
  in Calculation of Z for High Redshift Type Ia Supernovae

abstract:
  Systematic error in calculation of z for high redshift type Ia supernovae
could help explain unexpected luminosity values that indicate an accelerating
rate of expansion of the universe.


title: The Reverse Shock of SNR 1987A

abstract:
  The reverse shock of supernova remnant (SNR) 1987A emits in H-alpha and
Ly-alpha, and comes in two flavors: surface and interior. The former is due to
direct, impact excitation of hydrogen atoms crossing the shock, while the
latter is the result of charge transfer reactions between these atoms and
slower, post-shock ions. Interior and surface emission are analogous to the
broad- and narrow-line components observed in Balmer-dominated SNRs. I
summarize a formalism to derive line intensities and ratios in these SNRs, as
well as a study of the transition zone in supernova shocks; I include an
appendix where I derive in detail the ratio of broad to narrow H-alpha
emission. Further study of the reverse shock emission from SNR 1987A will allow
us to predict when it will vanish and further investigate the origins of the
interior emission.


title: Carbon Nanostructures as an Electromechanical Bicontinuum

abstract:
  A two-field model provides an unifying framework for elasticity, lattice
dynamics and electromechanical coupling in graphene and carbon nanotubes,
describes optical phonons, nontrivial acoustic branches, strain-induced gap
opening, gap-induced phonon softening, doping-induced deformations, and even
the hexagonal graphenic Brillouin zone, and thus explains and extends a
previously disparate accumulation of analytical and computational results.


title:
3.8-Micron Photometry During the Secondary Eclipse of the Extrasolar
  Planet HD 209458b

abstract:
  We report infrared photometry of the extrasolar planet HD 209458b during the
time of secondary eclipse (planet passing behind the star). Observations were
acquired during two secondary eclipses at the NASA Infrared Telescope Facility
(IRTF) in September 2003. We used a circular variable filter (1.5-percent
bandpass) centered at 3.8 microns to isolate the predicted flux peak of the
planet at this wavelength. Residual telluric absorption and instrument
variations were removed by offsetting the telescope to nearby bright comparison
stars at a high temporal cadence. Our results give a secondary eclipse depth of
0.0013 +/- 0.0011, not yet sufficient precision to detect the eclipse, whose
expected depth is approximately 0.002 - 0.003. We here elucidate the current
observational limitations to this technique, and discuss the approach needed to
achieve detections of hot Jupiter secondary eclipses at 3.8 microns from the
ground.


title: Ke4 decays and Wigner cusp

abstract:
  The NA48/2 experiment at the CERN SPS collected in 2003 and 2004 large
samples of the decays K+- -> pi+ pi- e+- nu (Ke4+-), K+- -> pi0 pi0 e+- nu
(Ke400) and K+- -> pi0 pi0 pi+-. From the Ke4+- form factors and from the cusp
in the M00^2 distribution of the K+- -> pi0 pi0 pi+- events, the pi-pi
scattering lengths a00 and a20 could be extracted. This measurement is a
fundamental test of Chiral Perturbation Theory (ChPT). The branching fraction
and form factors of the Ke400 decay were precisely measured, using a much
larger data sample than in previous experiments. An improved measurement of the
slope parameters for the decay K+- -> pi0 pi0 pi+- showed evidence for a
non-zero value of k.


title: Antenna Combining for the MIMO Downlink Channel

abstract:
  A multiple antenna downlink channel where limited channel feedback is
available to the transmitter is considered. In a vector downlink channel
(single antenna at each receiver), the transmit antenna array can be used to
transmit separate data streams to multiple receivers only if the transmitter
has very accurate channel knowledge, i.e., if there is high-rate channel
feedback from each receiver. In this work it is shown that channel feedback
requirements can be significantly reduced if each receiver has a small number
of antennas and appropriately combines its antenna outputs. A combining method
that minimizes channel quantization error at each receiver, and thereby
minimizes multi-user interference, is proposed and analyzed. This technique is
shown to outperform traditional techniques such as maximum-ratio combining
because minimization of interference power is more critical than maximization
of signal power in the multiple antenna downlink. Analysis is provided to
quantify the feedback savings, and the technique is seen to work well with user
selection and is also robust to receiver estimation error.


title: Quantum State Transfer with Spin Chains

abstract:
  The thesis covers various aspects of quantum state transfer in permanently
coupled spin systems.


title: Thistlethwaite's theorem for virtual links

abstract:
  The celebrated Thistlethwaite theorem relates the Jones polynomial of a link
with the Tutte polynomial of the corresponding planar graph. We give a
generalization of this theorem to virtual links. In this case, the graph will
be embedded into a (higher genus) surface. For such graphs we use the
generalization of the Tutte polynomial discovered by B.Bollobas and O.Riordan.


title: Colliding Branes and Formation of Spacetime Singularities

abstract:
  We construct a class of analytic solutions with two free parameters to the
five-dimensional Einstein field equations, which represents the collision of
two timelike 3-branes. We study the local and global properties of the
spacetime, and find that spacelike singularities generically develop after the
collision, due to the mutual focus of the two branes. Non-singular spacetime
can be constructed only in the case where both of the two branes violate the
energy conditions.


title:
Hitting probabilities for systems of non-linear stochastic heat
  equations with multiplicative noise

abstract:
  We consider a system of d non-linear stochastic heat equations in spatial
dimension 1 driven by d-dimensional space-time white noise. The non-linearities
appear both as additive drift terms and as multipliers of the noise. Using
techniques of Malliavin calculus, we establish upper and lower bounds on the
one-point density of the solution u(t,x), and upper bounds of Gaussian-type on
the two-point density of (u(s,y),u(t,x)). In particular, this estimate
quantifies how this density degenerates as (s,y) converges to (t,x). From these
results, we deduce upper and lower bounds on hitting probabilities of the
process {u(t,x)}_{t \in \mathbb{R}_+, x \in [0,1]}, in terms of respectively
Hausdorff measure and Newtonian capacity. These estimates make it possible to
show that points are polar when d >6 and are not polar when d<6. We also show
that the Hausdorff dimension of the range of the process is 6 when d>6, and
give analogous results for the processes t \mapsto u(t,x) and x \mapsto u(t,x).
Finally, we obtain the values of the Hausdorff dimensions of the level sets of
these processes.


title: Mutant knots and intersection graphs

abstract:
  We prove that if a finite order knot invariant does not distinguish mutant
knots, then the corresponding weight system depends on the intersection graph
of a chord diagram rather than on the diagram itself. The converse statement is
easy and well known. We discuss relationship between our results and certain
Lie algebra weight systems.


title:
Acoustic resonances in microfluidic chips: full-image micro-PIV
  experiments and numerical simulations

abstract:
  We show that full-image micro-PIV analysis in combination with images of
transient particle motion is a powerful tool for experimental studies of
acoustic radiation forces and acoustic streaming in microfluidic chambers under
piezo-actuation in the MHz range. The measured steady-state motion of both
large 5 um and small 1 um particles can be understood in terms of the acoustic
eigenmodes or standing ultra-sound waves in the given experimental
microsystems. This interpretation is supported by numerical solutions of the
corresponding acoustic wave equation.


title:
Observations towards early-type stars in the ESO-POP survey: II --
  searches for intermediate and high velocity clouds

abstract:
  We present CaII K and TiII optical spectra of early-type stars taken mainly
from the UVES Paranal Observatory Project, plus HI 21-cm spectra from the
Vila-Elisa and Leiden-Dwingeloo surveys, which are employed to obtain distances
to intermediate and high velocity clouds. HI emission at a velocity of -117
km/s towards the sightline HD 30677 with NHI=1.7x10^19 cm-2 has no
corresponding CaII K absorption, which has a signal-to-noise (S/N) ratio of
610. The star has a spectroscopically determined distance of 2.7-kpc, and hence
sets this as a firm lower distance limit towards Anti-Centre cloud ACII.
Towards another sightline (HD 46185), HI at +122 km/s and NHI=1.2x10^19 cm-2 is
seen. The CaII K spectrum has a S/N = 780, although no absorption is observed
at the cloud velocity. This similarly places a firm lower distance limit of
2.9-kpc towards this parcel of gas that may be an intermediate velocity cloud.
The lack of intermediate velocity (IV) CaII K absorption towards HD 196426 at a
S/N = 500 reinforces a lower distance limit of 700-pc towards this part of
Complex gp, where NHI is 1.1x10^19 cm-2 and velocity is +78 km/s. Additionally,
no IV CaII K is seen in absorption in the spectrum of HD 19445, which is strong
in HI with NHI=8x10^19 cm-2 at -42 km/s, placing a firm although uninteresting
lower distance limit of 39-pc to this part of IV South. Finally, no HV CaII K
absorption is seen towards HD 115363 at a S/N = 410, placing a lower distance
of 3.2-kpc towards the HVC gas at velocity of +224 km/s and NHI=5.2x10^19 cm-2.
This gas is in the same region of the sky as complex WE (Wakker 2001), but at
higher velocities. The non-detection of CaII K absorption sets a lower distance
of 3.2-kpc towards the HVC, which is unsurprising if this feature is indeed
related to the Magellanic System.


title: Physisorption of Nucleobases on Graphene

abstract:
  We report the results of our first-principles investigation on the
interaction of the nucleobases adenine (A), cytosine (C), guanine (G), thymine
(T), and uracil (U) with graphene, carried out within the density functional
theory framework, with additional calculations utilizing Hartree--Fock plus
second-order Moeller-Plesset perturbation theory. The calculated binding energy
of the nucleobases shows the following hierarchy: G > T ~ C ~ A > U, with the
equilibrium configuration being very similar for all five of them. Our results
clearly demonstrate that the nucleobases exhibit significantly different
interaction strengths when physisorbed on graphene. The stabilizing factor in
the interaction between the base molecule and graphene sheet is dominated by
the molecular polarizability that allows a weakly attractive dispersion force
to be induced between them. The present study represents a significant step
towards a first-principles understanding of how the base sequence of DNA can
affect its interaction with carbon nanotubes, as observed experimentally.


title: Low Density Lattice Codes

abstract:
  Low density lattice codes (LDLC) are novel lattice codes that can be decoded
efficiently and approach the capacity of the additive white Gaussian noise
(AWGN) channel. In LDLC a codeword x is generated directly at the n-dimensional
Euclidean space as a linear transformation of a corresponding integer message
vector b, i.e., x = Gb, where H, the inverse of G, is restricted to be sparse.
The fact that H is sparse is utilized to develop a linear-time iterative
decoding scheme which attains, as demonstrated by simulations, good error
performance within ~0.5dB from capacity at block length of n = 100,000 symbols.
The paper also discusses convergence results and implementation considerations.


title:
The Haunted Halos of Andromeda and Triangulum: A panorama of galaxy
  formation in action

abstract:
  We present a deep photometric survey of M31, conducted with the CFHT and INT,
covering the inner 50 kpc of the galaxy, the Southern quadrant out to 150 kpc,
and extending to M33. This is the first systematic panoramic study of this very
outermost region of galaxies. We detect several streams and other large-scale
structures, and two new dwarf galaxies: And XV and XVI. The discovery of
substructure on the minor axis, together with the fact that the light profile
between 0.5 < R < 1.3 follows the exponential ``extended disk'', is
particularly important in shedding light on the mixed and sometimes conflicting
results reported in previous studies. Underlying the substructures lies a
faint, metal-poor, smooth and extremely extended halo, reaching out to at least
150 kpc. The smooth halo component in M31 has a profile that can be fit with a
Hernquist model of immense scale radius ~55 kpc, almost a factor of 4 larger
than theoretical predictions. Alternatively a power-law with exponent -1.91 +/-
0.11 can be fit to the profile. The total luminosity of this structure is
similar to that of the halo of the Milky Way. This vast, smooth, underlying
halo is reminiscent of a classical monolithic model and completely unexpected
from modern galaxy formation models. M33 is also found to have an extended
metal-poor halo component, which can be fit with a Hernquist model also of
scale radius ~55 kpc. These extended slowly-decreasing halos will provide a
challenge and strong constraints for further modeling. [Abridged]


title:
Using conceptual metaphor and functional grammar to explore how language
  used in physics affects student learning

abstract:
  This paper introduces a theory about the role of language in learning
physics. The theory is developed in the context of physics students' and
physicists' talking and writing about the subject of quantum mechanics. We
found that physicists' language encodes different varieties of analogical
models through the use of grammar and conceptual metaphor. We hypothesize that
students categorize concepts into ontological categories based on the
grammatical structure of physicists' language. We also hypothesize that
students over-extend and misapply conceptual metaphors in physicists' speech
and writing. Using our theory, we will show how, in some cases, we can explain
student difficulties in quantum mechanics as difficulties with language.


title: Supersymmetry versus Gauge Symmetry on the Heterotic Landscape

abstract:
  One of the goals of the landscape program in string theory is to extract
information about the space of string vacua in the form of statistical
correlations between phenomenological features that are otherwise uncorrelated
in field theory. Such correlations would thus represent predictions of string
theory that hold independently of a vacuum-selection principle. In this paper,
we study statistical correlations between two features which are likely to be
central to any potential description of nature at high energy scales: gauge
symmetries and spacetime supersymmetry. We analyze correlations between these
two kinds of symmetry within the context of perturbative heterotic string
vacua, and find a number of striking features. We find, for example, that the
degree of spacetime supersymmetry is strongly correlated with the probabilities
of realizing certain gauge groups, with unbroken supersymmetry at the string
scale tending to favor gauge-group factors with larger rank. We also find that
nearly half of the heterotic landscape is non-supersymmetric and yet
tachyon-free at tree level; indeed, less than a quarter of the tree-level
heterotic landscape exhibits any supersymmetry at all at the string scale.


title:
Reversed flow at low frequencies in a microfabricated AC electrokinetic
  pump

abstract:
  Microfluidic chips have been fabricated to study electrokinetic pumping
generated by a low voltage AC signal applied to an asymmetric electrode array.
A measurement procedure has been established and followed carefully resulting
in a high degree of reproducibility of the measurements. Depending on the ionic
concentration as well as the amplitude of the applied voltage, the observed
direction of the DC flow component is either forward or reverse. The impedance
spectrum has been thoroughly measured and analyzed in terms of an equivalent
circuit diagram. Our observations agree qualitatively, but not quantitatively,
with theoretical models published in the literature.


title: Energy of 4-Dimensional Black Hole, etc

abstract:
  In this letter I suggest possible redefinition of mass density, not depending
on speed of the mass element, which leads to a more simple stress-energy for an
object. I calculate energy of black hole.


title: Multi-Higgs U(1) Lattice Gauge Theory in Three Dimensions

abstract:
  We study the three-dimensional compact U(1) lattice gauge theory with $N$
Higgs fields numerically. This model is relevant to multi-component
superconductors, antiferromagnetic spin systems in easy plane, inflational
cosmology, etc. For N=2, the system has a second-order phase transition line
$\tilde{c}_1(c_2)$ in the $c_2$(gauge coupling)$-c_1$(Higgs coupling) plane,
which separates the confinement phase and the Higgs phase. For N=3, the
critical line is separated into two parts; one for $c_2 \alt 2.25$ with
first-order transitions, and the other for $c_2 \agt 2.25$ with second-order
transitions.


title: Identifying Dark Matter Burners in the Galactic center

abstract:
  If the supermassive black hole (SMBH) at the center of our Galaxy grew
adiabatically, then a dense "spike" of dark matter is expected to have formed
around it. Assuming that dark matter is composed primarily of weakly
interacting massive particles (WIMPs), a star orbiting close enough to the SMBH
can capture WIMPs at an extremely high rate. The stellar luminosity due to
annihilation of captured WIMPs in the stellar core may be comparable to or even
exceed the luminosity of the star due to thermonuclear burning. The model thus
predicts the existence of unusual stars, i.e. "WIMP burners", in the vicinity
of an adiabatically grown SMBH. We find that the most efficient WIMP burners
are stars with degenerate electron cores, e.g. white dwarfs (WD) or degenerate
cores with envelopes. If found, such stars would provide evidence for the
existence of particle dark matter and could possibly be used to establish its
density profile. In our previous paper we computed the luminosity from WIMP
burning for a range of dark matter spike density profiles, degenerate core
masses, and distances from the SMBH. Here we compare our results with the
observed stars closest to the Galactic center and find that they could be
consistent with WIMP burners in the form of degenerate cores with envelopes. We
also cross-check the WIMP burner hypothesis with the EGRET observed flux of
gamma-rays from the Galactic center, which imposes a constraint on the dark
matter spike density profile and annihilation cross-section. We find that the
EGRET data is consistent with the WIMP burner hypothesis. New high precision
measurements by GLAST will confirm or set stringent limits on a dark matter
spike at the Galactic center, which will in turn support or set stringent
limits on the existence of WIMP burners at the Galactic center.


title: Instabilities in the time-dependent neutrino disc in Gamma-Ray Bursts

abstract:
  We investigate the properties and evolution of accretion tori formed after
the coalescence of two compact objects. At these extreme densities and
temperatures, the accreting torus is cooled mainly by neutrino emission
produced primarily by electron and positron capture on nucleons (beta
reactions). We solve for the disc structure and its time evolution by
introducing a detailed treatment of the equation of state which includes
photodisintegration of helium, the condition of beta-equilibrium, and neutrino
opacities. We self-consistently calculate the chemical equilibrium in the gas
consisting of helium, free protons, neutrons and electron-positron pairs and
compute the chemical potentials of the species, as well as the electron
fraction throughout the disc. We find that, for sufficiently large accretion
rates (> 10 solar masses per second), the inner regions of the disk become
opaque and develop a viscous and thermal instability. The identification of
this instability might be relevant for GRB observations.


title: Complete integrable systems with unconfined singularities

abstract:
  We prove that any globally periodic rational discrete system in K^k(where K
denotes either R or C), has unconfined singularities, zero algebraic entropy
and it is complete integrable (that is, it has as many functionally independent
first integrals as the dimension of the phase space). In fact, for some of
these systems the unconfined singularities are the key to obtain first
integrals using the Darboux-type method of integrability.


title: On the largest prime factor of the Mersenne numbers

abstract:
  Let P(k) be the largest prime factor of the positive integer k. In this
paper, we prove that the series $\sum_{n\ge 1}\frac{(\log n)^a}{P(2^n-1)}$ is
convergent for each constant a<1/2, which gives a more precise form of a result
of C. L. Stewart from 1977.


title:
Developing the Galactic diffuse emission model for the GLAST Large Area
  Telescope

abstract:
  Diffuse emission is produced in energetic cosmic ray (CR) interactions,
mainly protons and electrons, with the interstellar gas and radiation field and
contains the information about particle spectra in distant regions of the
Galaxy. It may also contain information about exotic processes such as dark
matter annihilation, black hole evaporation etc. A model of the diffuse
emission is important for determination of the source positions and spectra.
Calculation of the Galactic diffuse continuum gamma-ray emission requires a
model for CR propagation as the first step. Such a model is based on theory of
particle transport in the interstellar medium as well as on many kinds of data
provided by different experiments in Astrophysics and Particle and Nuclear
Physics. Such data include: secondary particle and isotopic production cross
sections, total interaction nuclear cross sections and lifetimes of radioactive
species, gas mass calibrations and gas distribution in the Galaxy (H_2, H I, H
II), interstellar radiation field, CR source distribution and particle spectra
at the sources, magnetic field, energy losses, gamma-ray and synchrotron
production mechanisms, and many other issues. We are continuously improving the
GALPROP model and the code to keep up with a flow of new data. Improvement in
any field may affect the Galactic diffuse continuum gamma-ray emission model
used as a background model by the GLAST LAT instrument. Here we report about
the latest improvements of the GALPROP and the diffuse emission model.


title: Prompt Emission of High Energy Photons from Gamma Ray Bursts

abstract:
  Within the internal shock scenario we consider different mechanisms of high
energy ($>1$ MeV) photon production inside a Gamma Ray Burst (GRB) fireball and
derive the expected high energy photon spectra from individual GRBs during the
prompt phase. The photon spectra of leptonic and hadronic origins are compared
within different sets of parameter regimes. Our results suggest that the high
energy emission is dominated by the leptonic component if fraction of shock
energy carried by electrons is not very small (e.g. $\epsilon_e > 10^{-3}$).
For very small values of $\epsilon_e$ the hadronic emission component could be
comparable to or even exceed the leptonic component in the GeV-TeV regime.
However, in this case a much larger energy budget of the fireball is required
to account for the same level of the observed sub-MeV spectrum. The fireballs
are therefore extremely inefficient in radiation. For a canonical fireball bulk
Lorentz factor (e.g. $\Gamma=400$), emissions above $\sim 10$ GeV are
attenuated by two-photon pair production processes. For a fireball with an even
higher Lorentz factor, the cutoff energy is higher, and emissions of 10 TeV -
PeV due to $\pi^0$-decay can also escape from the internal shocks. The flux
level is however too low to be detected by current TeV detectors, and these
photons also suffer attenuation by external soft photons.


title: On the classification of Floer-type theories

abstract:
  In this paper we outline a program for the classification of Floer-type
theories, (or defining invariants of finite type for families). We consider
Khovanov complexes as a local system on the space of knots introduced by V.
Vassiliev and construct the wall-crossing morphism. We extend this system to
the singular locus by the cone of this morphism and introduce the definition of
the local system of finite type. This program can be further generalized to the
manifolds of dimension 3 and 4.


title: Siegel's theorem for Drinfeld modules

abstract:
  We prove an analog of Siegel's theorem for integral points in the context of
Drinfeld modules. The result holds for finitely generated submodules of the
additive group over a function field of transcendence dimension 1.


title:
On the Exponential Decay of the n-point Correlation Functions and the
  Analyticity of the Pressure

abstract:
  The goal of this paper is to provide estimates leading to a direct proof of
the exponential decay of the n-point correlation functions for certain
unbounded models of Kac type. The methods are based on estimating higher order
derivatives of the solution of the Witten Laplacian equation on one forms
associated with the hamiltonian of the system. We also provide a formula for
the Taylor coefficients of the pressure that is suitable for a direct proof the
analyticity.


title:
A dynamical version of the Mordell-Lang conjecture for the additive
  group

abstract:
  We prove a dynamical version of the Mordell-Lang conjecture in the context of
Drinfeld modules. We use analytic methods similar to the ones employed by
Skolem, Chabauty, and Coleman for studying diophantine equations.


title:
Fabrication of Analog Electronics for Serial Readout of Silicon Strip
  Sensors

abstract:
  A set of analog electronics boards for serial readout of silicon strip
sensors was fabricated. A commercially available amplifier is mounted on a
homemade hybrid board in order to receive analog signals from silicon strip
sensors. Also, another homemade circuit board is fabricated in order to
translate amplifier control signals into a suitable format and to provide bias
voltage to the amplifier as well as to the silicon sensors. We discuss
technical details of the fabrication process and performance of the circuit
boards we developed.


title:
On the reductive Borel-Serre compactification: $L^p$-cohomology of
  arithmetic groups (for large $p$)

abstract:
  The $L^2$-cohomology of a locally symmetric variety is known to have the
topological interpretation as the intersection homology of its Baily-Borel
Satake compactification. In this article, we observe that even without the
Hermitian hypothesis, the $L^p$-cohomology of an arithmetic quotient, for $p$
finite and sufficiently large, is isomorphic to the ordinary cohomology of its
reductive Borel-Serre compactification. We use this to generalize a theorem of
Mumford concerning homogeneous vector bundles, their invariant Chern forms and
the canonical extensions of the bundles; here, though, we are referring to
canonical extensions to the reductive Borel-Serre compactification of any
arithmetic quotient. To achieve that, we give a systematic discussion of vector
bundles and Chern classes on stratified


title:
The $^4$He total photo-absorption cross section with two- plus
  three-nucleon interactions from chiral effective field theory

abstract:
  The total photo-absorption cross section of $^4$He is evaluated
microscopically using two- (NN) and three-nucleon (NNN) interactions based upon
chiral effective field theory ($\chi$EFT). The calculation is performed using
the Lorentz integral transform method along with the {\em ab initio} no-core
shell model approach. An important feature of the present study is the
consistency of the NN and NNN interactions and also, through the Siegert
theorem, of the two- and three-body current operators. This is due to the
application of the $\chi$EFT framework. The inclusion of the NNN interaction
produces a suppression of the low-energy peak and enhancement of the
high-energy tail of the cross section. We compare to calculations obtained
using other interactions and to representative experiments. The rather confused
experimental situation in the giant resonance region prevents discrimination
among different interaction models.


title: Comment on "Mass and Width of the Lowest Resonance in QCD"

abstract:
  I. Caprini's, G. Colangelo's, and H. Leutwyler's (CCL) article "Mass and
Width of the Lowest Resonance in QCD", Phys. Rev. Lett. 96, 132001 (2006)
[hep-ph/0512364], is critically reviewed. The present comment is devoted to
complement a recent experimental discussion (D.V. Bugg, J. Phys. G 34, 151
(2007) [hep-ph/0608081]) of short-comings in the CCL analysis, by presenting
theoretical arguments pointing at a serious flaw in the theoretical formalism
used by CCL, and also at the unlikeliness of their tiny error bars in the
sigma-meson mass and width. The criticism made in the comment applies
analogously to the analysis on the kappa-meson mass performed in the article
"The K0*(800) scalar resonance from Roy-Steiner representations of pi K
scattering" published as S. Descotes-Genon and B. Moussallam, Eur. Phys. J. C
48, 553 (2006) [hep-ph/0607133].


title:
True and Apparent Scaling: The Proximity of the Markov-Switching
  Multifractal Model to Long-Range Dependence

abstract:
  In this paper, we consider daily financial data of a collection of different
stock market indices, exchange rates, and interest rates, and we analyze their
multi-scaling properties by estimating a simple specification of the
Markov-switching multifractal model (MSM). In order to see how well the
estimated models capture the temporal dependence of the data, we estimate and
compare the scaling exponents $H(q)$ (for $q = 1, 2$) for both empirical data
and simulated data of the estimated MSM models. In most cases the multifractal
model appears to generate `apparent' long memory in agreement with the
empirical scaling laws.


title: SkyMapper and the Southern Sky Survey - a resource for the southern sky

abstract:
  SkyMapper is amongst the first of a new generation of dedicated, wide-field
survey telescopes. The 1.3m SkyMapper telescope features a 5.7 square degree
field-of-view Cassegrain imager and will see first light in late 2007. The
primary goal of the facility is to conduct the Southern Sky Survey a six
colour, six epoch survey of the southern sky. The survey will provide
photometry for objects between 8th and 23rd magnitude with global photometric
accuracy of 0.03 magnitudes and astrometry to 50 mas. This will represent a
valuable scientific resource for the southern sky and in addition provide a
basis for photometric and astrometric calibration of imaging data.


title:
Tautological classes on moduli spaces of curves with linear series and a
  push-forward formula when $\rho=0$

abstract:
  We define tautological Chow classes on the moduli space of curves with linear
series. In the case where the forgetful morphism to the moduli space of curves
has relative dimension zero, we describe the images of these classes in the
Chow group of Mgbar. As an application, we compute the (virtual) slopes of
several different classes of divisors on Mgbar.