title: Constructive proof of extended Kapranov theorem

abstract:
  Kapranov Theorem is a well known generalization of Newton-Puiseux theorem for
the case of several variables.
  This theorem is stated mainly in the context of tropical geometry. We present
a new, constructive proof, that also characterizes the possible principal terms
of points in a hypersurface contained in the algebraic torus $(K^*)^n$.


title:
A sharp threshold for minimum bounded-depth and bounded-diameter
  spanning trees and Steiner trees in random networks

abstract:
  In the complete graph on n vertices, when each edge has a weight which is an
exponential random variable, Frieze proved that the minimum spanning tree has
weight tending to zeta(3)=1/1^3+1/2^3+1/3^3+... as n goes to infinity. We
consider spanning trees constrained to have depth bounded by k from a specified
root. We prove that if k > log_2 log n+omega(1), where omega(1) is any function
going to infinity with n, then the minimum bounded-depth spanning tree still
has weight tending to zeta(3) as n -> infinity, and that if k < log_2 log n,
then the weight is doubly-exponentially large in log_2 log n - k. It is NP-hard
to find the minimum bounded-depth spanning tree, but when k < log_2 log n -
omega(1), a simple greedy algorithm is asymptotically optimal, and when k >
log_2 log n+omega(1), an algorithm which makes small changes to the minimum
(unbounded depth) spanning tree is asymptotically optimal. We prove similar
results for minimum bounded-depth Steiner trees, where the tree must connect a
specified set of m vertices, and may or may not include other vertices. In
particular, when m = const * n, if k > log_2 log n+omega(1), the minimum
bounded-depth Steiner tree on the complete graph has asymptotically the same
weight as the minimum Steiner tree, and if 1 <= k <= log_2 log n-omega(1), the
weight tends to (1-2^{-k}) sqrt{8m/n} [sqrt{2mn}/2^k]^{1/(2^k-1)} in both
expectation and probability. The same results hold for minimum bounded-diameter
Steiner trees when the diameter bound is 2k; when the diameter bound is
increased from 2k to 2k+1, the minimum Steiner tree weight is reduced by a
factor of 2^{1/(2^k-1)}.


title: Wall crossing in local Calabi Yau manifolds

abstract:
  We study the BPS states of a D6-brane wrapping the conifold and bound to
collections of D2 and D0 branes. We find that in addition to the complexified
Kahler parameter of the rigid sphere it is necessary to introduce an extra real
parameter to describe BPS partition functions and marginal stability walls. The
supergravity approach to BPS state-counting gives a simple derivation of
results of Szendroi concerning Donaldson-Thomas theory on the noncommutative
conifold. This example also illustrates some interesting limitations on the
supergravity approach to BPS state-counting and wall-crossing.


title: Partition Function of Spacetime

abstract:
  We consider a microscopic model of spacetime, where spacetime is assumed to
be a specific graph with Planck size quantum black holes on its vertices. As a
thermodynamical system under consideration we take a certain uniformly
accelerating, spacelike two-surface of spacetime which we call, for the sake of
brevity and simplicity, as {\it acceleration surface}. Using our model we
manage to obtain an explicit and surprisingly simple expression for the
partition function of an acceleration surface. Our partition function implies,
among other things, the Unruh and the Hawking effects. It turns out that the
Unruh and the Hawking effects are consequences of a specific phase transition,
which takes place in spacetime, when the temperature of spacetime equals, from
the point of view of an observer at rest with respect to an acceleration
surface, to the Unruh temperature measured by that observer. When constructing
the partition function of an acceleration surface we are forced to introduce a
quantity which plays the role of thermal energy of the surface. An
interpretation of that quantity as energy in a normal manner yields Einstein's
field equation with a vanishing cosmological constant for general matter
fields.


title:
Generalized Demailly-Semple jet bundles and holomorphic mappings into
  complex manifolds

abstract:
  Motivated by the Green-Griffiths conjecture, we study maximal rank
holomorphic maps from $\C^p$ into complex manifolds. When $p>1$ such maps
should in principle be more tractable than entire curves. We extend to this
setting the jet-bundles techniques introduced by Semple, Green-Griffiths and
Demailly. Our main application is the non-existence of maximal rank holomorphic
maps from $\C^2$ into the very general degree $d$ hypersurface in $\bP^4$, as
soon as $d\geq 93.$


title:
Serial correlation and heterogeneous volatility in financial markets:
  beyond the LeBaron effect

abstract:
  We study the relation between serial correlation of financial returns and
volatility at intraday level for the S&P500 stock index. At daily and weekly
level, serial correlation and volatility are known to be negatively correlated
(LeBaron effect). While confirming that the LeBaron effect holds also at
intraday level, we go beyond it and, complementing the efficient market
hyphotesis (for returns) with the heterogenous market hyphotesis (for
volatility), we test the impact of unexpected volatility, defined as the part
of volatility which cannot be forecasted, on the presence of serial
correlations in the time series. We show that unexpected volatility is instead
positively correlated with intraday serial correlation.


title:
Comment on "Spin and Orbital Angular Momentum in Gauge Theories" by X.
  S. Chen et. al. (PRL100, 232002 (2008))

abstract:
  The individual parts of the total angular momentum operator in interacting
theories cannot satisfy the canonical angular momentum commutation rule,
including those proposed in the above paper. Furthermore, the operators in the
new proposal a) are non-local in general gauge, b) do not have proper Lorentz
transformation properties, and c) do not have any known physical measurements.


title:
Limitations of anthropic predictions for the cosmological constant
  $\Lambda$: Cosmic Heat Death of Anthropic Observers

abstract:
  This paper investigates anthropic bounds on the vacuum energy $\Lambda$. We
first consider the possibility of cosmic observers existing at any random time
(including the future) for constant $\Lambda$, and take into account the
suppression of new structure formation as the universe approaches its eternal
DeSitter (DS) geometry. Structures that collapse prior to the era of
$\Lambda$-domination will lose causal contact with our Hubble volume within a
finite (short) conformal time $\tau_{\ast}$. Any remnants within our Hubble
volume then suffer a cosmological heat death after the universe becomes DS. The
probability for finding observers by random measurements in the volume bound by
the DeSitter horizon is $P \simeq 0$, and it is a simple consequence of the
information loss problem for eternal DS spaces resulting from the finite and
constant value of its temperature $T_{DS} \simeq \Lambda^{-1/2}$ and entropy $S
= 3/(G\Lambda)$. By contrast, for geometries with $\Lambda = 0$, structures can
condense and entropy production can continue without bounds at any epoch. The
probability of finding observers in $\Lambda = 0$ geometries is thus
overwhelming higher than in DS spaces. As a result, anthropic reasoning does
not explain the small but nonzero vacuum energy observed in our universe. We
also address the case where observers are considered only at a specially chosen
time -- like the present epoch -- but relax the allowed values of starting
density fluctuations and hence the redshift of galaxy formation. In this latter
case, the bounds on a $\Lambda$ can be millions of times larger than previous
estimates -- and the observed value. We thus conclude that anthropic reasoning
has limited predictive power.


title:
Properties of X-ray Binaries in the Magellanic Clouds from RXTE and
  Chandra Observations

abstract:
  The X-ray binary population of the SMC is very different from that of the
Milky Way consisting, with one exception, entirely of transient pulsating
Be/neutron star binaries. We have now been monitoring these SMC X-ray pulsars
for over 10 years using the Rossi X-ray Timing Explorer with observations
typically every week. The RXTE observations have been complemented with surveys
made using the Chandra observatory. The RXTE observations are non-imaging but
enable detailed studies of pulsing sources. In contrast, Chandra observations
can provide precise source locations and detections of sources at lower flux
levels, but do not provide the same timing information or the extended duration
light curves that RXTE observations do. We summarize the results of these
monitoring programs which provide insights into both the differences between
the SMC and the Milky Way, and the details of the accretion processes in X-ray
pulsars.


title: Sequential adaptive compressed sampling via Huffman codes

abstract:
  There are two main approaches in compressed sensing: the geometric approach
and the combinatorial approach. In this paper we introduce an information
theoretic approach and use results from the theory of Huffman codes to
construct a sequence of binary sampling vectors to determine a sparse signal.
Unlike other approaches, our approach is adaptive in the sense that each
sampling vector depends on the previous sample. The number of measurements we
need for a k-sparse vector in n-dimensional space is no more than O(k log n)
and the reconstruction is O(k).


title:
The potential of large germanium detector arrays for solar-axion
  searches utilizing the axio-electric effect for detection

abstract:
  The sensitivities of large arrays of low-background germanium detectors for
solar axion searches are investigated in the context of three coupling
scenarios. A search was made for the 14.4-keV axion branch from the
M1-transition in the thermally excited 57Fe in the solar core in 80 kgd of data
from the IGEX Dark Matter experiment published earlier. In one scenario, the
direct couplings of axions to hadrons and to electrons were assumed to be in
the range of Peccei-Quinn (PQ) scale, 3x105 GeV < fPQ < 7x105 GeV. This
scenario is excluded by the IGEX data. In a second case, at the same PQ scale,
coupling to photons and to electrons are suppressed. The IGEX data partially
excludes this scenario depending on the degree of suppression. In the third
case, the PQ-scale for all couplings is assumed to be in the range: 3x106 GeV<
fPQ <7x106 GeV. Detection rates in Ge for all three scenarios are presented.


title: Leptonic Pion Decay And Physics Beyond The Electroweak Standard Model

abstract:
  The ratio of branching ratios in leptonic pion decay $R_{\pi} \equiv
(\Gamma(\pi^- \to e \nu_e))/(\Gamma(\pi^- \to \mu \nu_\mu))$ is a powerfully
sensitive probe of new interactions beyond the electroweak standard model. This
is due to the chirality suppression of the standard model amplitude for the
decay, which results in a precise prediction for the ratio, and suppressed
amplitudes for new contributions to interfere with. We calculate, including QCD
corrections, the contributions to $R_{\pi}$ arising from a broad selection of
standard model extensions to which it is sensitive, including: R-parity
violating interactions in supersymmetric theories, theories with light
(electroweak scale) leptoquark degrees of freedom, non-minimal models of extra
doublet Higgs bosons, models in which the quarks and leptons are composite both
with and without supersymmetry, and models with strong TeV scale gravitational
interactions. Comparing with existing measurements of $R_{\pi}$ we provide
limits on each of these classes of models; our calculations also represent
state of the art theoretical benchmarks against which the results from the
upcoming round of leptonic pion decay experiments may be compared.


title:
On the radiative efficiencies, Eddington ratios, and duty cycles of
  luminous high-redshift quasars

abstract:
  We investigate the characteristic radiative efficiency \epsilon, Eddington
ratio \lambda, and duty cycle P_0 of high-redshift active galactic nuclei
(AGN), drawing on measurements of the AGN luminosity function at z=3-6 and,
especially, on recent measurements of quasar clustering at z=3-4.5 from the
Sloan Digital Sky Survey. The free parameters of our models are \epsilon,
\lambda, and the normalization, scatter, and redshift evolution of the relation
between black hole mass \mbh and halo virial velocity V_vir. We compute the
luminosity function from the implied growth of the black hole mass function and
the quasar correlation length from the bias of the host halos. We test our
adopted formulae for the halo mass function and halo bias against measurements
from the large N-body simulation developed by the MICE collaboration. The
strong clustering of AGNs observed at z=3 and, especially, at z=4 implies that
massive black holes reside in rare, massive dark matter halos. Reproducing the
observed luminosity function then requires high efficiency \epsilon and/or low
Eddington ratio \lambda, with a lower limit (based on 2\sigma agreement with
the measured z=4 correlation length) \epsilon> 0.7\lambda/(1+0.7\lambda),
implying \epsilon > 0.17 for \lambda > 0.25. Successful models predict high
duty cycles, P_0~0.2, 0.5, and 0.9 at z=3.1, 4.5 and 6, respectively, and they
require that the fraction of halo baryons locked in the central black hole is
much larger than the locally observed value. The rapid drop in the abundance of
the massive and rare host halos at z>7 implies a proportionally rapid decline
in the number density of luminous quasars, much stronger than simple
extrapolations of the z=3-6 luminosity function would predict. (abridged)


title:
Quantum site percolation on triangular lattice and the integer quantum
  Hall effect

abstract:
  Generic classical electron motion in a strong perpendicular magnetic field
and random potential reduces to the bond percolation on a square lattice. Here
we point out that for certain smooth 2D potentials with 120 degrees rotational
symmetry this problem reduces to the site percolation on a triangular lattice.
We use this observation to develop an approximate analytical description of the
integer quantum Hall transition. For this purpose we devise a quantum
generalization of the real-space renormalization group (RG) treatment of the
site percolation on the triangular lattice. In quantum case, the RG
transformation describes the evolution of the distribution of the $3\times 3$
scattering matrix at the sites. We find the fixed point of this distribution
and use it to determine the critical exponent, $\nu$, for which we find the
value $\nu \approx 2.3-2.76$. The RG step involves only a single Hikami box,
and thus can serve as a minimal RG description of the quantum Hall transition.


title: Constraints on Neutrino Masses from Weak Lensing

abstract:
  The weak lensing (WL) distortions of distant galaxy images are sensitive to
neutrino masses by probing the suppression effect on clustering strengths of
total matter in large-scale structure. We use the latest measurement of WL
correlations, the CFHTLS data, to explore constraints on neutrino masses. We
find that, while the WL data alone cannot place a stringent limit on neutrino
masses due to parameter degeneracies, the constraint can be significantly
improved when combined with other cosmological probes, the WMAP 5-year (WMAP5)
data and the distance measurements of type-Ia supernovae (SNe) and baryon
acoustic oscillations (BAO). The upper bounds on the sum of neutrino masses are
m_tot = 1.1, 0.76 and 0.54 eV (95% CL) for WL+WMAP5, WMAP5+SNe+BAO, and
WL+WMAP5+SNe+BAO, respectively, assuming a flat LCDM model with finite-mass
neutrinos. In deriving these constraints, our analysis includes the
non-Gaussian covariances of the WL correlation functions to properly take into
account significant correlations between different angles.


title: Curvature in the scaling relations of early-type galaxies

abstract:
  We select a sample of about 50,000 early-type galaxies from the Sloan Digital
Sky Survey (SDSS), calibrate fitting formulae which correct for known problems
with photometric reductions of extended objects, apply these corrections, and
then measure a number of pairwise scaling relations in the corrected sample. We
show that, because they are not seeing corrected, the use of Petrosian-based
quantities in magnitude limited surveys leads to biases, and suggest that this
is one reason why Petrosian-based analyses of BCGs have failed to find
significant differences from the bulk of the early-type population. These
biases are not present when seeing-corrected parameters derived from
deVaucouleur fits are used. Most of the scaling relations we study show
evidence for curvature: the most luminous galaxies have smaller velocity
dispersions, larger sizes, and fainter surface brightnesses than expected if
there were no curva-ture. These statements remain true if we replace
luminosities with stellar masses; they suggest that dissipation is less
important at the massive end. There is curvature in the dynamical to stellar
mass relation as well: the ratio of dynamical to stellar mass increases as
stellar mass increases, but it curves upwards from this scaling both at small
and large stellar masses. In all cases, the curvature at low masses becomes
apparent when the sample becomes dominated by objects with stellar masses
smaller than 3 x 10^10 M_Sun. We quantify all these trends using second order
polynomials; these generally provide significantly better description of the
data than linear fits, except at the least luminous end.


title:
Improved Standardization of Type II-P Supernovae: Application to an
  Expanded Sample

abstract:
  In the epoch of precise and accurate cosmology, cross-confirmation using a
variety of cosmographic methods is paramount to circumvent systematic
uncertainties. Owing to progenitor histories and explosion physics differing
from those of Type Ia SNe (SNe Ia), Type II-plateau supernovae (SNe II-P) are
unlikely to be affected by evolution in the same way. Based on a new analysis
of 17 SNe II-P, and on an improved methodology, we find that SNe II-P are good
standardizable candles, almost comparable to SNe Ia. We derive a tight Hubble
diagram with a dispersion of 10% in distance, using the simple correlation
between luminosity and photospheric velocity introduced by Hamuy & Pinto 2002.
We show that the descendent method of Nugent et al. 2006 can be further
simplified and that the correction for dust extinction has low statistical
impact. We find that our SN sample favors, on average, a very steep dust law
with total to selective extinction R_V<2. Such an extinction law has been
recently inferred for many SNe Ia. Our results indicate that a distance
measurement can be obtained with a single spectrum of a SN II-P during the
plateau phase combined with sparse photometric measurements.


title: The luminosity and stellar mass Fundamental Plane of early-type galaxies

abstract:
  From a sample of ~50000 early-type galaxies from the SDSS, we measured the
traditional Fundamental Plane in four bands. We then replaced luminosity with
stellar mass, and measured the "stellar mass" FP. The FP steepens slightly as
one moves from shorter to longer wavelengths: the orthogonal fit has slope 1.40
in g and 1.47 in z. The FP is thinner at longer wavelengths: scatter is 0.062
dex in g, 0.054 dex in z. The scatter is larger at small galaxy sizes/masses;
at large masses measurement errors account for essentially all of the observed
scatter. The FP steepens further when luminosity is replaced with stellar mass,
to slope ~ 1.6. The intrinsic scatter also reduces further, to 0.048 dex. Since
color and stellar mass-to-light ratio are closely related, this explains why
color can be thought of as the fourth FP parameter. However, the slope of the
stellar mass FP remains shallower than the value of 2 associated with the
virial theorem. This is because the ratio of dynamical to stellar mass
increases at large masses as M_d^0.17. The face-on view of the stellar mass
kappa-space suggests that there is an upper limit to the stellar density for a
given dynamical mass, and this decreases at large masses: M_*/R_e^3 ~ M_d^-4/3.
We also study how the estimated coefficients a and b of the FP are affected by
other selection effects (e.g. excluding small sigma biases a high; excluding
fainter L biases a low). These biases are seen in FPs which have no intrinsic
curvature, so the observation that a and b scale with L and sigma is not, by
itself, evidence that the Plane is warped. We show that the FP appears to curve
sharply downwards at the small mass end, and more gradually downwards towards
larger masses. Whereas the drop at small sizes is real, most of the latter
effect is due to correlated errors.


title: Anatomy of the Bar Instability in Cuspy Dark Matter Halos

abstract:
  We examine the bar instability in galactic models with an exponential disk
and a cuspy dark matter (DM) halo with a Navarro-Frenk-White (NFW) cosmological
density profile. We construct equilibrium models from a 3-integral composite
distribution function that are subject to the bar instability. We generate a
sequence of models with a range of mass resolution from 1.8K to 18M particles
in the disk and 10K to 100M particles in the halo along with a multi-mass model
with an effective resolution of ~10^10 particles. We describe how mass
resolution affects the bar instability, including its linear growth phase, the
buckling instability, pattern speed decay through the resonant transfer of
angular momentum to the DM halo, and the possible destruction of the halo cusp.
Our higher resolution simulations show a converging spectrum of discrete
resonance interactions between the bar and DM halo orbits. As the pattern speed
decays, orbital resonances sweep through most of the DM halo phase space and
widely distribute angular momentum among the halo particles. The halo does not
develop a flat density core and preserves the cusp, except in the region
dominated by gravitational softening. The formation of the bar increases the
central stellar density and the DM is compressed adiabatically increasing the
halo central density by 1.7X. Overall, the evolution of the bar displays a
convergent behavior for halo particle numbers between 1M and 10M particles,
when comparing bar growth, pattern speed evolution, the DM halo density profile
and a nonlinear analysis of the orbital resonances. Higher resolution
simulations clearly illustrate the importance of discrete resonances in
transporting the angular momentum from the bar to the halo.


title:
The interaction between the projectile and the target core in single
  ionization of helium by 100 MeV/u C$^{6+}$ and 1 GeV/u U$^{92+}$ ions

abstract:
  We consider single ionization of helium by fast highly charged ions. The
ionization is treated as a three-body problem which involves the 'active'
target electron, the target core (consisting of the target nucleus and the
'passive' target electron) and the projectile-ion. We show that, unless the
transverse momentum transfer in the collision is large, the deviation of the
interaction between the projectile and the target core from the purely coulomb
law has a weak effect on the ionization. In particular, the account of this
deviation does not enable one to get an agreement with experimental data on the
fully differential cross section for the electron emission into the so called
perpendicular plane.


title:
Epsilon Indi Ba, Bb: a spectroscopic study of the nearest known brown
  dwarfs

abstract:
  The discovery of Epsilon Indi Ba and Bb, a nearby binary brown dwarf system
with a main-sequence companion, allows a concerted campaign to characterise the
physical parameters of two T dwarfs providing benchmarks against which
atmospheric and evolutionary models can be tested. Some recent observations
suggest the models at low mass and intermediate age may not reflect reality
with, however, few conclusive tests.
  We are carrying out a comprehensive characterisation of these, the nearest
known brown dwarfs, to allow constraints to be placed upon models of cool field
dwarfs. We present broadband photometry from the V- to M-band and the
individual spectrum of both components from 0.6-5.1 microns at a resolution of
up to R=5000. A custom analytic profile fitting routine was implemented to
extract the blended spectra and photometry of both components separated by 0.7
arcsec. We confirm the spectral types to be T1 and T6, and notably, we do not
detect lithium at 6708A in the more massive object which may be indicative both
of the age of the system and the mass of the components.


title:
Production and polarization of Upsilon mesons in the k_T-factorization
  approach in more detail

abstract:
  In the framework of the k_T-factorization approach, the production and
polarization of Upsilon mesons at the Fermilab Tevatron is considered, and a
comparision of the calculated double differential distributions and spin
alignment parameter $\alpha$ with the D0 experimental data is shown. We argue
that measuring the double differential cross section and the polarization of
upsilonium states can serve as a crucial test discriminating two competing
theoretical approaches to the parton dynamics in QCD.


title:
Surface morphology and magnetic anisotropy of Fe/MgO(001) films
  deposited at oblique incidence

abstract:
  We have studied surface morphology and magnetic properties of Fe/MgO(001)
films deposited at an angle varying between 0o and 60o with respect to the
surface normal and with azimuth along the Fe[010] or the Fe[110] direction. Due
to shadowing, elongated grains appear on the film surface for deposition at
sufficiently large angle. X-ray reflectivity reveals that, depending on the
azimuthal direction, films become either rougher or smoother for oblique
deposition. For deposition along Fe[010] the pronounced uniaxial magnetic
anisotropy (UMA) results in the occurrence of reversed two-step and of
three-step hysteresis loops. For deposition along Fe[110] the growth-induced
UMA is much weaker, causing a small rotation of the easy axes.


title:
The IceCube Data Acquisition System: Signal Capture, Digitization, and
  Timestamping

abstract:
  IceCube is a km-scale neutrino observatory under construction at the South
Pole with sensors both in the deep ice (InIce) and on the surface (IceTop). The
sensors, called Digital Optical Modules (DOMs), detect, digitize and timestamp
the signals from optical Cherenkov-radiation photons. The DOM Main Board (MB)
data acquisition subsystem is connected to the central DAQ in the IceCube
Laboratory (ICL) by a single twisted copper wire-pair and transmits packetized
data on demand. Time calibration is maintained throughout the array by regular
transmission to the DOMs of precisely timed analog signals, synchronized to a
central GPS-disciplined clock. The design goals and consequent features,
functional capabilities, and initial performance of the DOM MB, and the
operation of a combined array of DOMs as a system, are described here.
Experience with the first InIce strings and the IceTop stations indicates that
the system design and performance goals have been achieved.


title: Continuity of quantum channel capacities

abstract:
  We prove that a broad array of capacities of a quantum channel are
continuous. That is, two channels that are close with respect to the diamond
norm have correspondingly similar communication capabilities. We first show
that the classical capacity, quantum capacity, and private classical capacity
are continuous, with the variation on arguments epsilon apart bounded by a
simple function of epsilon and the channel's output dimension. Our main tool is
an upper bound of the variation of output entropies of many copies of two
nearby channels given the same initial state; the bound is linear in the number
of copies. Our second proof is concerned with the quantum capacities in the
presence of free backward or two-way public classical communication. These
capacities are proved continuous on the interior of the set of non-zero
capacity channels by considering mutual simulation between similar channels.


title:
Near-IR Search for Lensed Supernovae Behind Galaxy Clusters - II. First
  Detection and Future Prospects

abstract:
  Powerful gravitational telescopes in the form of massive galaxy clusters can
be used to enhance the light collecting power over a limited field of view by
about an order of magnitude in flux. This effect is exploited here to increase
the depth of a survey for lensed supernovae at near-IR wavelengths. A pilot SN
search program conducted with the ISAAC camera at VLT is presented. Lensed
galaxies behind the massive clusters A1689, A1835 and AC114 were observed for a
total of 20 hours split into 2, 3 and 4 epochs respectively, separated by
approximately one month to a limiting magnitude J<24 (Vega). Image subtractions
including another 20 hours worth of archival ISAAC/VLT data were used to search
for transients with lightcurve properties consistent with redshifted
supernovae, both in the new and reference data. The feasibility of finding
lensed supernovae in our survey was investigated using synthetic lightcurves of
supernovae and several models of the volumetric Type Ia and core-collapse
supernova rates as a function of redshift. We also estimate the number of
supernova discoveries expected from the inferred star formation rate in the
observed galaxies. The methods consistently predict a Poisson mean value for
the expected number of SNe in the survey between N_SN=0.8 and 1.6 for all
supernova types, evenly distributed between core collapse and Type Ia SN. One
transient object was found behind A1689, 0.5" from a galaxy with photometric
redshift z_gal=0.6 +- 0.15. The lightcurve and colors of the transient are
consistent with being a reddened Type IIP SN at z_SN=0.59. The lensing model
predicts 1.4 magnitudes of magnification at the location of the transient,
without which this object would not have been detected in the near-IR ground
based search described in this paper (unlensed magnitude J~25). (abridged)


title:
Higher Asymptotics of Unitarity in "Quantization Commutes with
  Reduction"

abstract:
  Let M be a compact Kaehler manifold equipped with a Hamiltonian action of a
compact Lie group G. In [Invent. Math. 67 (1982), no.~3, 515--538], Guillemin
and Sternberg showed that there is a geometrically natural isomorphism between
the G-invariant quantum Hilbert space over M and the quantum Hilbert space over
the symplectic quotient M//G. This map, though, is not in general unitary, even
to leading order in h-bar.
  In [Comm. Math. Phys. 275 (2007), no.~2, 401--422], Hall and the author
showed that when the metaplectic correction is included, one does obtain a map
which, while not in general unitary for any fixed h-bar, becomes unitary in the
semiclassical limit that h-bar goes to zero. (cf. the work of Ma and Zhang in
[C. R. Math. Acad. Sci. Paris 341 (2005), no.~5, 297--302], and [Ast\'erisque
No. 318 (2008), viii+154 pp.]). The unitarity of the classical
Guillemin--Sternberg map and the metaplectically corrected analogue is measured
by certain functions on the symplectic quotient M//G. In this paper, we give
precise expressions for these functions, and compute complete asymptotic
expansions for them as h-bar goes to zero.


title: Exponential-Time Approximation of Hard Problems

abstract:
  We study optimization problems that are neither approximable in polynomial
time (at least with a constant factor) nor fixed parameter tractable, under
widely believed complexity assumptions. Specifically, we focus on Maximum
Independent Set, Vertex Coloring, Set Cover, and Bandwidth.
  In recent years, many researchers design exact exponential-time algorithms
for these and other hard problems. The goal is getting the time complexity
still of order $O(c^n)$, but with the constant $c$ as small as possible. In
this work we extend this line of research and we investigate whether the
constant $c$ can be made even smaller when one allows constant factor
approximation. In fact, we describe a kind of approximation schemes --
trade-offs between approximation factor and the time complexity.
  We study two natural approaches. The first approach consists of designing a
backtracking algorithm with a small search tree. We present one result of that
kind: a $(4r-1)$-approximation of Bandwidth in time $O^*(2^{n/r})$, for any
positive integer $r$.
  The second approach uses general transformations from exponential-time exact
algorithms to approximations that are faster but still exponential-time. For
example, we show that for any reduction rate $r$, one can transform any
$O^*(c^n)$-time algorithm for Set Cover into a $(1+\ln r)$-approximation
algorithm running in time $O^*(c^{n/r})$. We believe that results of that kind
extend the applicability of exact algorithms for NP-hard problems.


title: Structured vector bundles define differential K-theory

abstract:
  A equivalence relation, preserving the Chern-Weil form, is defined between
connections on a complex vector bundle. Bundles equipped with such an
equivalence class are called Structured Bundles, and their isomorphism classes
form an abelian semi-ring. By applying the Grothedieck construction one obtains
the ring K, elements of which, modulo a complex torus of dimension the sum of
the odd Betti numbers of the base, are uniquely determined by the corresponding
element of ordinary K and the Chern-Weil form. This construction provides a
simple model of differential K-theory, c.f.Hopkins-Singer (2005), as well as a
useful codification of vector bundles with connection.


title: Combinatorial models of expanding dynamical systems

abstract:
  We define iterated monodromy groups of more general structures than partial
self-covering. This generalization makes it possible to define a natural notion
of a combinatorial model of an expanding dynamical system. We prove that a
naturally defined "Julia set" of the generalized dynamical systems depends only
on the associated iterated monodromy group. We show then that the Julia set of
every expanding dynamical system is an inverse limit of simplicial complexes
constructed by inductive cut-and-paste rules.


title: Low eigenvalues and one-dimensional collapse

abstract:
  Our main result is that if a generic convex domain in $\R^n$ collapses to a
domain in $\R^{n-1}$, then the difference between the first two Dirichlet
eigenvalues of the Euclidean Laplacian, known as the fundamental gap, diverges.
The boundary of the domain need not be smooth, merely Lipschitz continuous. To
motivate the general case, we first prove the analogous result for triangular
and polygonal domains. In so doing, we prove that the first two eigenvalues of
triangular domains cannot be polyhomogeneous on the moduli space of triangles
without blowing up a certain point. Our results show that the gap generically
diverges under one dimensional collapse and is bounded only if the domain is
sufficiently close to a rectangle in two dimensions or a cylinder in higher
dimensions.


title:
Two-Dimensional Stellar Evolution Code Including Arbitrary Magnetic
  Fields. II. Precision Improvement and Inclusion of Turbulence and Rotation

abstract:
  In the second paper of this series we pursue two objectives. First, in order
to make the code more sensitive to small effects, we remove many approximations
made in Paper I. Second, we include turbulence and rotation in the
two-dimensional framework. The stellar equilibrium is described by means of a
set of five differential equations, with the introduction of a new dependent
variable, namely the perturbation to the radial gravity, that is found when the
non-radial effects are considered in the solution of the Poisson equation;
following the scheme of the first paper, we write the equations in such a way
that the two-dimensional effects can be easily disentangled. The key concept
introduced in this series is the equipotential surface. We use the underlying
cause-effect relation to develop a recurrence relation to calculate the
equipotential surface functions for uniform rotation, differential rotation,
rotation-like toroidal magnetic fields and turbulence. We also develop a more
precise code to numerically solve the two-dimensional stellar structure and
evolution equations based on the equipotential surface calculations. We have
shown that with this formulation we can achieve the precision required by
observations by appropriately selecting the convergence criterion. Several
examples are presented to show that the method works well. Since we are
interested in modeling the effects of a dynamo-type field on the detailed
envelope structure and global properties of the Sun, the code has been
optimized for short timescales phenomena (down to 1 yr). The time dependence of
the code has so far been tested exclusively to address such problems.


title:
The radial BAO scale and Cosmic Shear, a new observable for
  Inhomogeneous Cosmologies

abstract:
  As an alternative explanation of the dimming of distant supernovae it has
recently been advocated that we live in a special place in the Universe near
the centre of a large spherical void described by a Lemaitre-Tolman-Bondi (LTB)
metric. In this scenario, the Universe is no longer homogeneous and isotropic,
and the apparent late time acceleration is actually a consequence of spatial
gradients. We propose in this paper a new observable, the normalized cosmic
shear, written in terms of directly observable quantities, and calculable in
arbitrary inhomogeneous cosmologies. This will allow future surveys to
determine whether we live in a homogeneous universe or not. In this paper we
also update our previous observational constraints from geometrical measures of
the background cosmology. We include the Union Supernovae data set of 307 Type
Ia supernovae, the CMB acoustic scale and the first measurement of the radial
baryon acoustic oscillation scale. Even though the new data sets are
significantly more constraining, LTB models -- albeit with slightly larger
voids -- are still in excellent agreement with observations, at chi^2/d.o.f. =
307.7/(310-4)=1.005. Together with the paper we also publish the updated
easyLTB code used for calculating the models and for comparing them to the
observations.


title: Holographic Unhiggs

abstract:
  We propose an extra-dimensional approach to the unparticle Higgs (Unhiggs).
The non-local 4D Unhiggs action is derived as the boundary effective action of
a local 5D theory. We review the mechanism to generate unparticle spectra in
the context of warped soft-wall models. Gauge invariance can be simply
implemented and unitarity of the longitudinal WW scattering amplitude is
particularly transparent. Furthermore, the 5D approach uncovers a broader
spectrum of phenomenological possibilities. The Unhiggs is accompanied by
another continuum formed by Kaluza-Klein excitations of the Standard Model
gauge fields which, in some cases, may take over the leading role in
unitarizing WW scattering.


title:
C-axis Phonons in Fe-As Based Superconductors Investigated by Inelastic
  X-ray Scattering

abstract:
  In Fe-As based superconductors magnetism and superconductivity show strong
sensitivity to the lattice, suggesting a possibility of unconventional
electron-phonon coupling. We investigated c-axis polarized phonons in doped and
undoped BaFe2As2 by inelastic X-ray scattering. Phonon peak positions and
linewidths did not vary significantly as a function of doping either by Co or
by K. The linewidth of the Fe vibration shows unusual wavevector-dependence,
which may be due to hybridization with in-plane modes. Comparison with the
density functional theory shows significant difference for the energy of the
As-As vibrations (Raman active at the zone center) but not for the Fe-As
vibrations (infrared-active at the zone center). This behavior cannot be
explained by a 10% softening of Fe-As interaction strength as proposed
previously for in-plane polarized vibrations.


title: Cronin effect for protons and pions in pA collisions

abstract:
  Pions and protons production cross-sections are analyzed in proton-proton and
proton-nucleus collisions at the RHIC energy at midrapidity. We employ the pQCD
factorization scheme supplemented with the color-dipole formalism to
investigate the Cronin effect. We calculate the broadening in the color-dipole
approach for different centralities. Our main goal is to investigate, in a
parameter-free manner within a unified framework, how much of the cronin effect
for both pions and baryons comes from the transverse momentum broadening due to
initial partons multi-scatterings. We conclude that final-state effects in pA
collisions are important. Uncertainties in nuclear shadowing of various parton
distributions and parton fragmentation functions are also discussed.


title:
Calculation of Solar P-mode Oscillation Frequency Splittings Based on a
  Two-dimensional Solar Model

abstract:
  We compute the p-mode oscillation frequencies and frequency splittings that
arise in a two-dimensional model of the Sun that contains toroidal magnetic
fields in its interior.


title: Seiberg-Witten theory and matrix models

abstract:
  We derive a family of matrix models which encode solutions to the
Seiberg-Witten theory in 4 and 5 dimensions. Partition functions of these
matrix models are equal to the corresponding Nekrasov partition functions, and
their spectral curves are the Seiberg-Witten curves of the corresponding
theories. In consequence of the geometric engineering, the 5-dimensional case
provides a novel matrix model formulation of the topological string theory on a
wide class of non-compact toric Calabi-Yau manifolds. This approach also
unifies and generalizes other matrix models, such as the Eguchi-Yang matrix
model, matrix models for bundles over $P^1$, and Chern-Simons matrix models for
lens spaces, which arise as various limits of our general result.


title: New Approaches to Object Classification in Synoptic Sky Surveys

abstract:
  Digital synoptic sky surveys pose several new object classification
challenges. In surveys where real-time detection and classification of
transient events is a science driver, there is a need for an effective
elimination of instrument-related artifacts which can masquerade as transient
sources in the detection pipeline, e.g., unremoved large cosmic rays,
saturation trails, reflections, crosstalk artifacts, etc. We have implemented
such an Artifact Filter, using a supervised neural network, for the real-time
processing pipeline in the Palomar-Quest (PQ) survey. After the training phase,
for each object it takes as input a set of measured morphological parameters
and returns the probability of it being a real object. Despite the relatively
low number of training cases for many kinds of artifacts, the overall artifact
classification rate is around 90%, with no genuine transients misclassified
during our real-time scans. Another question is how to assign an optimal
star-galaxy classification in a multi-pass survey, where seeing and other
conditions change between different epochs, potentially producing inconsistent
classifications for the same object. We have implemented a star/galaxy
multipass classifier that makes use of external and a priori knowledge to find
the optimal classification from the individually derived ones. Both these
techniques can be applied to other, similar surveys and data sets.


title: FPT Algorithms and Kernels for the Directed $k$-Leaf Problem

abstract:
  A subgraph $T$ of a digraph $D$ is an {\em out-branching} if $T$ is an
oriented spanning tree with only one vertex of in-degree zero (called the {\em
root}). The vertices of $T$ of out-degree zero are {\em leaves}. In the {\sc
Directed $k$-Leaf} Problem, we are given a digraph $D$ and an integral
parameter $k$, and we are to decide whether $D$ has an out-branching with at
least $k$ leaves. Recently, Kneis et al. (2008) obtained an algorithm for the
problem of running time $4^{k}\cdot n^{O(1)}$. We describe a new algorithm for
the problem of running time $3.72^{k}\cdot n^{O(1)}$. In {\sc Rooted Directed
$k$-Leaf} Problem, apart from $D$ and $k$, we are given a vertex $r$ of $D$ and
we are to decide whether $D$ has an out-branching rooted at $r$ with at least
$k$ leaves. Very recently, Fernau et al. (2008) found an $O(k^3)$-size kernel
for {\sc Rooted Directed $k$-Leaf}. In this paper, we obtain an $O(k)$ kernel
for {\sc Rooted Directed $k$-Leaf} restricted to acyclic digraphs.


title:
Prospects for testing the nature of Sgr A*'s NIR flares on the basis of
  current VLT- and future VLTI-observations

abstract:
  Sagittarius A*, the supermassive compact object at the center of the Galaxy,
exhibits outbursts in the near infrared and X-ray domains. These flares are
likely due to energetic events very close to the central object, on a scale of
a few Schwarzschild radii. Optical interferometry will soon be able to provide
astrometry with an accuracy of this order (~10 muas). In this article we use
recent photometric near infrared data observed with the adaptive optics system
NACO at the Very Large Telescope combined with simulations in order to deploy a
method to test the nature of the flares and to predict the possible outcome of
observations with the Very Large Telescope Interferometer. To accomplish this
we implement a hot spot model and investigate its appearance for a remote
observer in terms of light curves and centroid tracks, based on general
relativistic ray tracing methods. First, we use a simplified model of a small
steady source in order to investigate the relativistic effects qualitatively. A
more realistic scenario is then being developed by fitting our model to
existing flare data. While indications for the spin of the black hole and
multiple images due to lensing effects are marginal in the light curves,
astrometric measurements offer the possibility to reveal these high-order
general relativistic effects. This study makes predictions on these astrometric
measurements and leads us to the conclusion that future infrared
interferometers will be able to detect proper motion of hot spots in the
vicinity of Sagittarius A*.


title:
Groping Toward Linear Regression Analysis: Newton's Analysis of
  Hipparchus' Equinox Observations

abstract:
  In February 1700, Isaac Newton needed a precise tropical year to design a new
universal calendar that would supersede the Gregorian one. However,
17th-Century astronomers were uncertain of the long-term variation in the
inclination of the Earth's axis and were suspicious of Ptolemy's equinox
observations. As a result, they produced a wide range of tropical years. Facing
this problem, Newton attempted to compute the length of the year on his own,
using the ancient equinox observations reported by a famous Greek astronomer
Hipparchus of Rhodes, ten in number. Though Newton had a very thin sample of
data, he obtained a tropical year only a few seconds longer than the correct
length. The reason lies in Newton's application of a technique similar to
modern regression analysis. Newton wrote down the first of the two so-called
'normal equations' known from the ordinary least-squares (OLS) method. In that
procedure, Newton seems to have been the first to employ the mean (average)
value of the data set, while the other leading astronomers of the era (Tycho
Brahe, Galileo, and Kepler) used the median. Fifty years after Newton, in 1750,
Newton's method was rediscovered and enhanced by Tobias Mayer. Remarkably, the
same regression method served with distinction in the late 1920s when the
founding fathers of modern cosmology, Georges Lemaitre (1927), Edwin Hubble
(1929), and Willem de Sitter (1930), employed it to derive the Hubble constant.


title: Renormalized transport of inertial particles in surface flows

abstract:
  Surface transport of inertial particles is investigated by means of the
perturbative approach, introduced by Maxey (J. Fluid Mech. 174, 441 (1987)),
which is valid in the case the deflections induced on the particle trajectories
by the fluid flow can be considered small. We consider a class of compressible
random velocity fields, in which the effect of recirculations is modelled by an
oscillatory component in the Eulerian time correlation profile. The main issue
we address here is whether fluid velocity fluctuations, in particular the
effect of recirculation, may produce nontrivial corrections to the streaming
particle velocity. Our result is that a small (large) degree of recirculation
is associated with a decrease (increase) of streaming with respect to a
quiescent fluid. The presence of this effect is confirmed numerically, away
from the perturbative limit. Our approach also allows us to calculate the
explicit expression for the eddy diffusivity, and to compare the efficiency of
diffusive and ballistic transport.


title:
Three Dimensional Structure and Energy Balance of a Coronal Mass
  Ejection

abstract:
  The Ultraviolet Coronagraph Spectrometer (UVCS) observed Doppler shifted
material of a partial Halo Coronal Mass Ejection (CME) on December 13 2001. The
observed ratio of [O V]/O V] is a reliable density diagnostic important for
assessing the state of the plasma. Earlier UVCS observations of CMEs found
evidence that the ejected plasma is heated long after the eruption. We have
investigated the heating rates, which represent a significant fraction of the
CME energy budget. The parameterized heating and radiative and adiabatic
cooling have been used to evaluate the temperature evolution of the CME
material with a time dependent ionization state model. The functional form of a
flux rope model for interplanetary magnetic clouds was also used to
parameterize the heating. We find that continuous heating is required to match
the UVCS observations. To match the O VI-bright knots, a higher heating rate is
required such that the heating energy is greater than the kinetic energy. The
temperatures for the knots bright in Ly$\alpha$ and C III emission indicate
that smaller heating rates are required for those regions. In the context of
the flux rope model, about 75% of the magnetic energy must go into heat in
order to match the O VI observations. We derive tighter constraints on the
heating than earlier analyses, and we show that thermal conduction with the
Spitzer conductivity is not sufficient to account for the heating at large
heights.


title:
SiO Outflow Signatures Toward Massive Young Stellar Objects with
  Linearly Distributed Methanol Masers

abstract:
  Methanol masers are often found in linear distributions, and it has been
hypothesized that these masers are tracing circumstellar accretion disks around
young massive stars. However, recent observations in H2 emission have shown
what appear to be outflows at similar angles to the maser distribution angles,
not perpendicular as expected in the maser-disk scenario. The main motivation
behind the observations presented here is to determine from the presence and
morphology of an independent outflow tracer, namely SiO, if there are indeed
outflows present in these regions and if they are consistent or inconsistent
with the maser-disk hypothesis. For ten sources with H2 emission we obtained
JCMT single dish SiO (6-5) observations to search for the presence of this
outflow indicator. We followed up those observations with ATCA interferometric
mapping of the SiO emission in the (2-1) line in six sources. The JCMT
observations yielded a detection in the SiO (6-5) line in nine of the ten
sources. All of the sources with bright SiO lines display broad line wings
indicative of outflow. A subset of the sources observed with the JCMT have
methanol maser velocities significantly offset from their parent cloud
velocities, supporting the idea that the masers in these sources are likely not
associated with circumstellar disks. The ATCA maps of the SiO emission show
five of the six sources do indeed have SiO outflows. The spatial orientations
of the outflows are not consistent with the methanol masers delineating disk
orientations. Overall, the observations presented here seem to provide further
evidence against the hypothesis that linearly distributed methanol masers
generally trace the orientations of circumstellar disks around massive young
stars.


title: Computational modelling of evolution: ecosystems and language

abstract:
  Recently, computational modelling became a very important research tool that
enables us to study problems that for decades evaded scientific analysis.
Evolutionary systems are certainly examples of such problems: they are composed
of many units that might reproduce, diffuse, mutate, die, or in some cases for
example communicate. These processes might be of some adaptive value, they
influence each other and occur on various time scales. That is why such systems
are so difficult to study. In this paper we briefly review some computational
approaches, as well as our contributions, to the evolution of ecosystems and
language. We start from Lotka-Volterra equations and the modelling of simple
two-species prey-predator systems. Such systems are canonical example for
studying oscillatory behaviour in competitive populations. Then we describe
various approaches to study long-term evolution of multi-species ecosystems. We
emphasize the need to use models that take into account both ecological and
evolutionary processes. Finally, we address the problem of the emergence and
development of language. It is becoming more and more evident that any theory
of language origin and development must be consistent with darwinian principles
of evolution. Consequently, a number of techniques developed for modelling
evolution of complex ecosystems are being applied to the problem of language.
We briefly review some of these approaches.


title: Fault-tolerant quantum computation versus Gaussian noise

abstract:
  We study the robustness of a fault-tolerant quantum computer subject to
Gaussian non-Markovian quantum noise, and we show that scalable quantum
computation is possible if the noise power spectrum satisfies an appropriate
"threshold condition." Our condition is less sensitive to very-high-frequency
noise than previously derived threshold conditions for non-Markovian noise.


title:
Absorptive part of meson--baryon scattering amplitude and baryon
  polarization in chiral perturbation theory

abstract:
  We compute the spin asymmetry and polarization of the final-state baryon in
its rest frame in two-body meson--baryon low-energy scattering with unpolarized
initial state, to lowest non-trivial order in BChPT. The required absorptive
amplitudes are obtained analytically at one-loop level. We discuss the
polarization results numerically for several meson--baryon processes. Even at
low energies above threshold, where BChPT can reasonably be expected to be
applicable, sizable values of polarization are found for some processes.


title: The 2dF-SDSS LRG and QSO Survey: The spectroscopic QSO catalogue

abstract:
  We present the final spectroscopic QSO catalogue from the 2dF-SDSS LRG and
QSO (2SLAQ) Survey. This is a deep, 18<g<21.85 (extinction corrected), sample
aimed at probing in detail the faint end of the broad line AGN luminosity
distribution at z<2.6. The candidate QSOs were selected from SDSS photometry
and observed spectroscopically with the 2dF spectrograph on the
Anglo-Australian Telescope. This sample covers an area of 191.9 deg^2 and
contains new spectra of 16326 objects, of which 8764 are QSOs, and 7623 are
newly discovered (the remainder were previously identified by the 2QZ and SDSS
surveys). The full QSO sample (including objects previously observed in the
SDSS and 2QZ surveys) contains 12702 QSOs. The new 2SLAQ spectroscopic data set
also contains 2343 Galactic stars, including 362 white dwarfs, and 2924 narrow
emission line galaxies with a median redshift of z=0.22. We present detailed
completeness estimates for the survey, based on modelling of QSO colours,
including host galaxy contributions. This calculation shows that at g~21.85 QSO
colours are significantly affected by the presence of a host galaxy up to
redshift z~1 in the SDSS ugriz bands. In particular we see a significant
reddening of the objects in g-i towards fainter g-band magnitudes. This
reddening is consistent with the QSO host galaxies being dominated by a stellar
population of age at least 2-3 Gyr. The full catalogue, including completeness
estimates, is available on-line at http://www.2slaq.info/


title: More on Lensing by a Cosmological Constant

abstract:
  The question of whether or not the cosmological constant affects the bending
of light around a concentrated mass has been the subject of some recent papers.
We present here a simple, specific and transparent example where $\Lambda$
bending clearly takes place, and where it is clearly neither a coordinate
effect nor an aberration effect. We then show that in some recent works using
perturbation theory the $\Lambda$ contribution was missed because of initial
too-stringent smallness assumptions. Namely: Our method has been to insert a
Kottler (Schwarzschild with $\Lambda$) vacuole into a Friedmann universe, and
to calculate the total bending within the vacuole. We assume that no more
bending occurs outside. It is important to observe that while the mass
contribution to the bending takes place mainly quite near the lens, the
$\Lambda$ bending continues throughout the vacuole. Thus if one deliberately
restricts one's search for $\Lambda$ bending to the immediate neighborhood of
the lens, one will not find it. Lastly, we show that the $\Lambda$ bending also
follows from standard Weyl focusing, and so again, it cannot be a coordinate
effect.


title:
A general theory of Finite State Backward Stochastic Difference
  Equations

abstract:
  By analogy with the theory of Backward Stochastic Differential Equations, we
define Backward Stochastic Difference Equations on spaces related to discrete
time, finite state processes. This paper considers these processes as
constructions in their own right, not as approximations to the continuous case.
We establish the existence and uniqueness of solutions under weaker assumptions
than are needed in the continuous time setting, and also establish a comparison
theorem for these solutions. The conditions of this theorem are shown to
approximate those required in the continuous time setting. We also explore the
relationship between the driver $F$ and the set of solutions; in particular, we
determine under what conditions the driver is uniquely determined by the
solution. Applications to the theory of nonlinear expectations are explored,
including a representation result.


title: Gamma N Delta Form Factors and Wigner Rotations

abstract:
  For more than 50 years the Delta N gamma form factors have been studied
experimentally, theoretically, and phenomenologically. Although there has been
substantial progress in understanding their behavior, there remains much work
to be done. A major tool used in many investigations is the Jones-Scadron Delta
rest frame parametrization of the three Delta N gamma form factors. We point
out that many studies utilizing this parametrization may not account for Wigner
rotations and the consequent helicity mixing that ensues when the Delta is not
at rest.


title:
Quantization Of Spin Direction For Solitary Waves In A Uniform Magnetic
  Field

abstract:
  It is known that there are nonlinear wave equations with localized solitary
wave solutions. Some of these solitary waves are stable (with respect to a
small perturbation of initial data) and have nonzero spin (nonzero intrinsic
angular momentum in the center of momentum frame). In this paper we consider
vector-valued solitary wave solutions to a nonlinear Klein-Gordon equation and
investigate the behavior of these spinning solitary waves under the influence
of an externally imposed uniform magnetic field. We find that the only
stationary spinning solitary wave solutions have spin parallel or anti-parallel
to the magnetic field direction.


title: Fibrations of simplicial sets

abstract:
  There are infinitely many variants of the notion of Kan fibration that,
together with suitable choices of cofibrations and the usual notion of weak
equivalence of simplicial sets, satisfy Quillen's axioms for a homotopy model
category. The combinatorics underlying these fibrations is purely finitary and
seems interesting both for its own sake and for its interaction with homotopy
types. To show that these notions of fibration are indeed distinct, one needs
to understand how iterates of Kan's Ex functor act on graphs and on nerves of
small categories.


title:
Free-space Excitation of Resonant Cavities formed from Cloaking
  Metamaterial

abstract:
  We propose a new class of resonant electromagnetic structures, and study
their response to free-space illumination. The structures consist of partial
cylindrical shells that have cloaking material properties proposed by Pendry et
al. These metamaterial shells have apertures that allow the propagation of
incident irradiation into an interior resonant cavity. We use full wave
time-harmonic analysis to study the field distribution inside the cavity, and
show that an analogue of Whispering Gallery Modes (WGMs) can be efficiently
excited via free-space illumination.


title: BPS Magnetic Monopole Bags

abstract:
  We explore the characteristics of spherical bags made of large numbers of BPS
magnetic monopoles. There are two extreme limits. In the Abelian bag, $N$ zeros
of the Higgs field are arranged in a quasiregular lattice on a sphere of radius
$R_{\rm cr} \sim N/v$, where $v$ is the Higgs vacuum expectation value. The
massive gauge fields of the theory are largely confined to a thin shell at this
radius that separates an interior with almost vanishing magnetic and Higgs
fields from an exterior region with long-range Coulomb magnetic and Higgs
fields. In the other limiting case, which we term a non-Abelian bag, the $N$
zeros of the Higgs field are all the origin, but there is again a thin shell of
radius $R_{\rm cr}$. In this case the region enclosed by this shell can be
viewed as a large monopole core, with small Higgs field but nontrivial massive
and massless gauge fields.


title: The Impact of Feedback on Disk Galaxy Scaling Relations

abstract:
  We use a disk galaxy evolution model to investigate the impact of mass
outflows (a.k.a. feedback) on disk galaxy scaling relations. Our model follows
the accretion, cooling, star formation and ejection of baryonic mass inside
growing dark matter haloes, with cosmologically motivated specific angular
momentum distributions. Models without feedback produce disks that are too
small and rotate too fast. Feedback reduces the baryonic masses of galaxies,
resulting in larger disks with lower rotation velocities. Models with feedback
can reproduce the zero points of the scaling relations between rotation
velocity, stellar mass and disk size, but only in the absence of adiabatic
contraction. Our feedback mechanism is maximally efficient in expelling mass,
but our successful models require 25% of the SN energy, or 100% of the SN
momentum, to drive the outflows. It remains to be seen whether such high
efficiencies are realistic or not. Our energy and momentum driven wind models
result in different slopes of various scaling relations, such as size - stellar
mass, stellar mass - halo mass, and metallicity - stellar mass. Observations
favor the energy driven wind at stellar masses below Mstar = 10^{10.5} Msun,
but the momentum driven wind model at high masses. The ratio between the
specific angular momentum of the baryons to that of the halo, (j_gal/m_gal), is
not unity in our models. Yet this is the standard assumption in models of disk
galaxy formation. Feedback preferentially ejects low angular momentum material
because star formation is more efficient at smaller galactic radii. This
results in (j_gal/m_gal) increasing with decreasing halo mass. This effect
helps to resolve the discrepancy between the high spin parameters observed for
dwarf galaxies with the low spin parameters predicted from LCDM. [Abridged]


title:
Algebras of twisted chiral differential operators and affine
  localization of $\frak{g}$-modules

abstract:
  We propose a notion of algebra of {\it twisted} chiral differential operators
over algebraic manifolds with vanishing 1st Pontrjagin class. We show that such
algebras possess families of modules depending on infinitely many complex
parameters, which we classify in terms of the corresponding algebra of twisted
differential operators. If the underlying manifold is a flag manifold, our
construction recovers modules over an affine Lie algebra parameterized by opers
over the Langlands dual Lie algebra. The spaces of global sections of
"smallest" such modules are irreducible $\ghat$-modules and all irreducible
$\frak{g}$-integrable $\ghat$-modules at the critical level arise in this way.


title: Linear Multistep Numerical Methods for Ordinary Differential Equations

abstract:
  A review of the most popular Linear Multistep (LM) Methods for solving
Ordinary Differential Equations numerically is presented. These methods are
first derived from first principles, and are discussed in terms of their order,
consistency, and various types of stability. Particular varieties of stability
that may not be familiar, are briefly defined first. The methods that are
included are the Adams-Bashforth Methods, Adams-Moulton Methods, and Backwards
Differentiation Formulas. Advantages and disadvantages of these methods are
also described. Not much prior knowledge of numerical methods or ordinary
differential equations is required, although knowledge of basic topics from
calculus is assumed.


title:
Quantum blockade and loop current induced by a single lattice defect in
  graphene nanoribbons

abstract:
  We investigate theoretically the electronic transport properties in narrow
graphene ribbons with an adatom-induced defect. It is found that the lowest
conductance step of a metallic graphene nanoribbon may develop a dip even down
to zero at certain values of the Fermi energy due to the defect. Accompanying
the occurrence of the conductance dip, a loop current develops around the
defect. We show how the properties of the conductance dip depend on the
parameters of the defect, such as the relative position and severity of the
defect as well as the width and edges of the graphene ribbons. In particular,
for metallic armchair-edges graphene nanoribbons, whether the conductance dip
appears or not, they can be controlled by choosing the position of the single
defect.


title: Elastic energy loss and longitudinal straggling of a hard jet

abstract:
  The elastic energy loss encountered by jets produced in deep-inelastic
scattering (DIS) off a large nucleus is studied in the collinear limit. In
close analogy to the case of (non-radiative) transverse momentum broadening,
which is dependent on the medium transport coefficient $\hat{q}$, a class of
medium enhanced higher twist operators which contribute to the non-radiative
loss of the forward light-cone momentum of the jet ($q^-$) are identified and
the leading correction in the limit of asymptotically high $q^-$ is isolated.
Based on these operator products, a new transport coefficient $\hat{e}$ is
motivated which quantifies the energy loss per unit length encountered by the
hard jet. These operator products are then computed, explicitly, in the case of
a similar hard jet traversing a deconfined quark-gluon-plasma (QGP) in the
hard-thermal-loop (HTL) approximation. This is followed by an evaluation of
sub-leading contributions which are suppressed by the light-cone momentum
$q^-$, which yields the longitudinal "straggling" i.e., a slight change in
light cone momentum due to the Brownian propagation through a medium with a
fluctuating color field.


title: Quantum Algorithms Using the Curvelet Transform

abstract:
  The curvelet transform is a directional wavelet transform over R^n, which is
used to analyze functions that have singularities along smooth surfaces (Candes
and Donoho, 2002). I demonstrate how this can lead to new quantum algorithms. I
give an efficient implementation of a quantum curvelet transform, together with
two applications: a single-shot measurement procedure for approximately finding
the center of a ball in R^n, given a quantum-sample over the ball; and, a
quantum algorithm for finding the center of a radial function over R^n, given
oracle access to the function. I conjecture that these algorithms succeed with
constant probability, using one quantum-sample and O(1) oracle queries,
respectively, independent of the dimension n -- this can be interpreted as a
quantum speed-up. To support this conjecture, I prove rigorous bounds on the
distribution of probability mass for the continuous curvelet transform. This
shows that the above algorithms work in an idealized "continuous" model.


title:
Function Model of the Teichm\"uller space of a closed hyperbolic Riemann
  Surface

abstract:
  We introduce a function model for the Teichm\"uller space of a closed
hyperbolic Riemann surface. Then we introduce a new metric by using the maximum
norm on the function space on the Teichm\"uller space. We prove that the
identity map from the Teichm\"uller space equipped with the usual Teichm\"uller
metric to the Teichm\"uller space equipped with this new metric is uniformly
continuous. Furthermore, we also prove that the inverse of the identity, that
is, the identity map from the Teichm\"uller space equipped with this new metric
to the Teichm\"uller space equipped with the usual Teichm\"uller metric, is
continuous. Therefore, the topology induced by the new metric is just the same
as the topology induced by the usual Teichm\"uller metric on the Teichm\"uller
space. We give a remark about the pressure metric and the Weil-Petersson
metric.


title: Quantum Coherence Effects in Four-level Diamond Atomic System

abstract:
  A symmetric four-level closed-loop $\diamondsuit$ type (the diamond
structure) atomic system driven by four coherent optical fields is
investigated. The system shows rich quantum interference and coherence
features. When symmetry of the system is broken, interesting phenomena such as
single and double dark resonances appear. As a result, the double
electromagnetically induced transparency effect is generated, which will
facilitate the implementation of quantum phase gate operation.


title:
Electrical properties of boron-doped MWNTs synthesized by hot-filament
  chemical vapor deposition

abstract:
  We have synthesized a large amount of boron-doped multiwalled carbon
nanotubes (MWNTs) by hot-filament chemical vapor deposition. The synthesis was
carried out in a flask using a methanol solution of boric acid as a source
material. The scanning electron microscopy, transmission electron microscopy,
and micro-Raman spectroscopy were performed to evaluate the structural
properties of the obtained MWNTs. In order to evaluate the electrical
properties, temperature dependence of resistivity was measured in an individual
MWNTs with four metal electrodes. The Ramman shifts suggest carrier injection
into the boron-doped MWNTs, but the resistivity of the MWNTs was high and
increased strongly with decreasing temperature. Defects induced by the plasma
may cause this enhanced resistivity.


title: Many-Quark Model with su(4) Algebraic Structure

abstract:
  With the use of a certain type of the Schwinger boson representation of the
su(4) algebra, the Bonn model for many-quark systems and an extension of the
model, in which the energies of the various exact states are controled, namely,
the energies are enhanced or de-enhanced, are investigated. Especially, the
triplet formation and the pairing correlation in many-quark states are
discussed. In the boson space, all the results are analytically expressed in
the exact forms.


title:
Light-cone QCD Sum Rules for the $\Lambda$ Baryon Electromagnetic Form
  Factors and its magnetic moment

abstract:
  We present the light-cone QCD sum rules up to twist 6 for the electromagnetic
form factors of the $\Lambda$ baryon. To estimate the magnetic moment of the
baryon, the magnetic form factor is fitted by the dipole formula. The numerical
value of our estimation is $\mu_\Lambda=-(0.64\pm0.04)\mu_N$, which is in
accordance with the experimental data and the existing theoretical results. We
find that it is twist 4 but not the leading twist distribution amplitudes that
dominate the results.


title:
Reality, locality and all that: "experimental metaphysics" and the
  quantum foundations

abstract:
  In recent decades there has been a resurge of interest in the foundations of
quantum theory, partly motivated by new experimental techniques, partly by the
emerging field of quantum information science. Old questions, asked since the
seminal article by Einstein, Podolsky and Rosen (EPR), are being revisited. The
work of John Bell has changed the direction of investigation by recognising
that those fundamental philosophical questions can have, after all, input from
experiment. Abner Shimony has aptly termed this new field of enquiry
"experimental metaphysics". The objective of this Thesis is to contribute to
that body of research, by formalising old concepts, proposing new ones, and
finding new results in well-studied areas. Without losing from sight that the
appeal of experimental metaphysics comes from the adjective, every major result
is followed by clear experimental proposals for quantum-atom optical setups.


title:
Hanohano: A Deep Ocean Anti-Neutrino Detector for Unique Neutrino
  Physics and Geophysics Studies

abstract:
  The science potential of a 10 kiloton deep-ocean liquid scintillation
detector for ~1 MeV energy scale electron anti-neutrinos has been studied. Such
an instrument, designed to be portable and function in the deep ocean (3-5 km)
can make unique measurements of the anti-neutrinos from radioactive decays in
the Earth'.s mantle. Ths information speaks to some of the most fundamental
questions in geology about the origin of the Earth, plat e tectonics, the
geomagnetic field and even somewhat indirectly to global warming. Measurements
in multiple locations will strengthen the potential insights. On the particle
physics side, we have identified a unique role in the study of anti-neutrinos
from a nuclear power complex, at a range of 55-60 km off shore. Not only can
precision measurements be made of most neutrino mixing parameters, including
$\theta_{13}$ (depending on magnitude), but the neutrino mass hierarchy can be
determined in a method not heretofore discussed, and one which does not rely
upon matter effects. This detector is under active study on paper, in the
laboratory, and at sea. An interdisciplinary and international collaboration is
in formation, and plans are in motion for a major proposal, to be followed by
construction over several years.


title:
Realistic interpretation of entangled state: a defense and application
  to Hardy's experiment

abstract:
  Two criticisms which have prevented the realistic interpretation of entangled
state from being widely accepted are addressed and shown to be unfounded. A
local realistic theory, which reproduces all the quantum probabilistic
predictions, is constructed for Hardy's experiment based on the realistic
interpretation of the entangled two-particle Hardy state.


title:
Statistical properties of determinantal point processes in
  high-dimensional Euclidean spaces

abstract:
  The goal of this paper is to quantitatively describe some statistical
properties of higher-dimensional determinantal point processes with a primary
focus on the nearest-neighbor distribution functions. Toward this end, we
express these functions as determinants of $N\times N$ matrices and then
extrapolate to $N\to\infty$. This formulation allows for a quick and accurate
numerical evaluation of these quantities for point processes in Euclidean
spaces of dimension $d$. We also implement an algorithm due to Hough \emph{et.
al.} \cite{hough2006dpa} for generating configurations of determinantal point
processes in arbitrary Euclidean spaces, and we utilize this algorithm in
conjunction with the aforementioned numerical results to characterize the
statistical properties of what we call the Fermi-sphere point process for $d =
1$ to 4. This homogeneous, isotropic determinantal point process, discussed
also in a companion paper \cite{ToScZa08}, is the high-dimensional
generalization of the distribution of eigenvalues on the unit circle of a
random matrix from the circular unitary ensemble (CUE). In addition to the
nearest-neighbor probability distribution, we are able to calculate Voronoi
cells and nearest-neighbor extrema statistics for the Fermi-sphere point
process and discuss these as the dimension $d$ is varied. The results in this
paper accompany and complement analytical properties of higher-dimensional
determinantal point processes developed in \cite{ToScZa08}.


title:
Competition between Surface Energy and Elastic Anisotropies in the
  Growth of Coherent Solid State Dendrites

abstract:
  A new phase field model of microstructural evolution is presented that
includes the effects of elastic strain energy. The model's thin interface
behavior is investigated by mapping it onto a recent model developed by
Echebarria et al (Phys Rev E, 70:061604,2004). Exploiting this thin interface
analysis the growth of solid state dendrites are simulated with diffuse
interfaces and the phase field and mechanical equilibrium equations are solved
in real space on an adaptive mesh. A morphological competition between surface
energy anisotropy and elastic anisotropy is examined. Two dimensional
simulations are reported that show that solid state dendritic structures
undergo a transition from a surface dominated [10] growth direction to an
elastically driven [11] growth direction by changes in the elastic anisotropy,
the surface anisotropy and the supersaturation. Using the curvature and strain
corrections to the equilibrium interfacial composition and linear stability
theory for isotropic precipitates as calculated by Mullins and Sekerka, the
dominant growth morphology is predicted.


title:
Energy and system size dependence of \phi meson production in Cu+Cu and
  Au+Au collisions

abstract:
  We study the beam-energy and system-size dependence of \phi meson production
(using the hadronic decay mode \phi -- K+K-) by comparing the new results from
Cu+Cu collisions and previously reported Au+Au collisions at \sqrt{s_NN} = 62.4
and 200 GeV measured in the STAR experiment at RHIC. Data presented are from
mid-rapidity (|y|<0.5) for 0.4 < pT < 5 GeV/c. At a given beam energy, the
transverse momentum distributions for \phi mesons are observed to be similar in
yield and shape for Cu+Cu and Au+Au colliding systems with similar average
numbers of participating nucleons. The \phi meson yields in nucleus-nucleus
collisions, normalised by the average number of participating nucleons, are
found to be enhanced relative to those from p+p collisions with a different
trend compared to strange baryons. The enhancement for \phi mesons is observed
to be higher at \sqrt{s_NN} = 200 GeV compared to 62.4 GeV. These observations
for the produced \phi(s\bar{s}) mesons clearly suggest that, at these collision
energies, the source of enhancement of strange hadrons is related to the
formation of a dense partonic medium in high energy nucleus-nucleus collisions
and cannot be alone due to canonical suppression of their production in smaller
systems.


title: Two years of flight of the Pamela experiment: results and perspectives

abstract:
  PAMELA is a satellite borne experiment designed to study with great accuracy
cosmic rays of galactic, solar, and trapped nature in a wide energy range
(protons: 80 MeV-700 GeV, electrons 50 MeV-400 GeV). Main objective is the
study of the antimatter component: antiprotons (80 MeV-190 GeV), positrons (50
MeV-270 GeV) and search for antinuclei with a precision of the order of
$10^{-8}$). The experiment, housed on board the Russian Resurs-DK1 satellite,
was launched on June, $15^{th}$ 2006 in a $350\times 600 km$ orbit with an
inclination of 70 degrees. In this work we describe the scientific objectives
and the performance of PAMELA in its first two years of operation. Data on
protons of trapped, secondary and galactic nature - as well as measurements of
the December $13^{th}$ 2006 Solar Particle Event - are also provided.


title: Edge chirality determination of graphene by Raman spectroscopy

abstract:
  Raman imaging on the edges of single layer micromechanical cleavage graphene
(MCG) was carried out. The intensity of disorder-induced Raman feature (D band
at ~1350 cm-1) was found to be correlated to the edge chirality: it is stronger
at the armchair edge and weaker at the zigzag edge. This shows that Raman
spectroscopy is a reliable and practical method to identify the chirality of
graphene edge and to help in determination of the crystal orientation. The
determination of graphene chirality is critically important for fundamental
study as well as for applications.


title:
Feasibility of Experimental Realization of Entangled Bose-Einstein
  Condensation

abstract:
  We examine the practical feasibility of the experimental realization of the
so-called entangled Bose-Einstein condensation (BEC), occurring in an entangled
state of two atoms of different species. We demonstrate that if the energy gap
remains vanishing, the entangled BEC persists as the ground state of the
concerned model in a wide parameter regime. We establish the experimental
accessibility of the isotropic point of the effective parameters, in which the
entangled BEC is the exact ground state, as well as the consistency with the
generalized Gross-Pitaevskii equations. The transition temperature is
estimated. Possible experimental implementations are discussed in detail.


title: Rotating Fermi gases in an anharmonic trap

abstract:
  Motivated by recent experiments on rotating Bose-Einstein condensates, we
investigate a rotating, polarized Fermi gas trapped in an anharmonic potential.
We apply a semiclassical expansion of the density of states in order to
determine how the thermodynamic properties depend on the rotation frequency.
The accuracy of the semiclassical approximation is tested and shown to be
sufficient for describing typical experiments. At zero temperature, rotating
the gas above a given frequency $\Omega_{\rm DO}$ leads to a `donut'-shaped
cloud which is analogous to the hole found in two-dimensional Bose-Einstein
condensates. The free expansion of the gas after suddenly turning off the trap
is considered and characterized by the time and rotation frequency dependence
of the aspect ratio. Temperature effects are also taken into account and both
low- and high-temperature expansions are presented for the relevant
thermodynamical quantities. In the high-temperature regime a virial theorem
approach is used to study the delicate interplay between rotation and
anharmonicity.


title:
Critical Metal Phase at the Anderson Metal-Insulator Transition with
  Kondo Impurities

abstract:
  It is well-known that magnetic impurities can change the symmetry class of
disordered metallic systems by breaking spin and time-reversal symmetry. At low
temperature these symmetries can be restored by Kondo screening. It is also
known that at the Anderson metal-insulator transition, wave functions develop
multifractal fluctuations with power law correlations. Here, we consider the
interplay of these two effects. We show that multifractal correlations open
local pseudogaps at the Fermi energy at some random positions in space. When
dilute magnetic impurities are at these locations, Kondo screening is strongly
suppressed. We find that when the exchange coupling J is smaller than a certain
value J*, the metal-insulator transition point extends to a critical region in
the disorder strength parameter and to a band of critical states. The width of
this critical region increases with a power of the concentration of magnetic
impurities.


title: Generic Uniqueness of Area Minimizing Disks for Extreme Curves

abstract:
  We show that for a generic nullhomotopic simple closed curve C in the
boundary of a compact, orientable, mean convex 3-manifold M with trivial second
homology, there is a unique area minimizing disk D embedded in M where the
boundary of D is C. We also show that the same is true for absolutely area
minimizing surfaces.


title:
Maximum Multiplicity of a Root of the Matching Polynomial of a Tree and
  Minimum Path Cover

abstract:
  We give a necessary and sufficient condition for the maximum multiplicity of
a root of the matching polynomial of a tree to be equal to the minimum number
of vertex disjoint paths needed to cover it.


title:
Photoluminescence sidebands of carbon nanotubes below the bright singlet
  excitonic levels: Coupling between dark excitons and K-point phonons

abstract:
  We performed detailed photoluminescence (PL) spectroscopy studies of three
different types of single-walled carbon nanotubes (SWNTs) by using samples that
contain essentially only one chiral type of SWNT, (6,5), (7,5), or (10,5). The
observed PL spectra unambiguously show the existence of an emission sideband at
~ 145 meV below the lowest singlet excitonic (E11) level, whose identity and
origin are now under debate. We find that the energy separation between the E11
level and the sideband is almost independent of the SWNT diameter. Based on
this, we ascribe the origin of the observed sideband to coupling between
K-point LO phonons and dipole-forbidden dark excitons, as recently suggested
based on the measurement of (6,5) SWNTs.


title: A multiquark description of the $D_{sJ}(2860)$ and $D_{sJ}(2700)$

abstract:
  Within a theoretical framework that accounts for all open-charm mesons,
including the $D_0^*(2308)$, the $D_{sJ}^*(2317)$ and the $D_{sJ}(2460)$, we
analyze the structure and explore possible quantum number assignments for the
$D_{sJ}(2860)$ and the $D_{sJ}(2700)$ mesons reported by BABAR and Belle
Collaborations. The open-charm sector is properly described if considered as a
combination of conventional quark-antiquark states and four--quark components.
All negative parity and $2^+$ states can be understood in terms only of $q\bar
q$ components, however the description of the $0^+$ and $1^+$ mesons is
improved whenever the mixing between two-- and four--quarks configurations is
included. We analyze all possible quantum number assignments for the
$D_{sJ}(2860)$ in terms of both $c\bar s$ and $cn\bar s\bar n$ configurations.
We discuss the role played by the electromagnetic and strong decay widths as
basic tools to distinguish among them. The broad structure reported by BABAR
near 2.7 GeV is also analyzed.


title: Initial and final de Sitter universes from modified $f(R)$ gravity

abstract:
  Viable models of modified gravity which satisfy both local as well as
cosmological tests are investigated. It is demonstrated that some versions of
such highly non-linear models exhibit multiply de Sitter universe solutions,
which often appear in pairs, being one of them stable and the other unstable.
It is explicitly shown that, for some values of the parameters, it is possible
to find several de Sitter spaces
  (as a rule, numerically); one of them may serve for the inflationary stage,
while the other can be used for the description of the dark energy epoch. The
numerical evolution of the effective equation of state parameter is also
presented, showing that these models can be considered as natural candidates
for the unification of early-time inflation with late-time acceleration through
dS critical points. Moreover, based on the de Sitter solutions, multiply SdS
universes are constructed which might also appear at the (pre-)inflationary
stage. Their thermodynamics are studied and free energies are compared.


title:
Osmotically driven flows in microchannels separated by a semipermeable
  membrane

abstract:
  We perform experimental investigations of osmotically driven flows in
artificial microchannels by studying the dynamics and structure of the front of
a sugar solution traveling in 200 um wide and 50-200 um deep microchannels. We
find that the sugar front travels with constant speed, and that this speed is
proportional to the concentration of the sugar solution and inversely
proportional to the depth of the channel. We propose a theoretical model,
which, in the limit of low axial flow resistance, predicts that the sugar front
indeed should travel with a constant velocity. The model also predicts an
inverse relationship between the depth of the channel and the speed and a
linear relation between the sugar concentration and the speed. We thus find
good agreement between the experimental results and the predictions of the
model. Our motivation for studying osmotically driven flows is that they are
believed to be responsible for the translocation of sugar in plants through the
phloem sieve element cells. Also, we suggest that osmotic elements can act as
integrated pumps with no movable parts in lab-on-a-chip systems.


title: Large deviations for Branching Processes in Random Environment

abstract:
  A branching process in random environment $(Z_n, n \in \N)$ is a
generalization of Galton Watson processes where at each generation the
reproduction law is picked randomly. In this paper we give several results
which belong to the class of {\it large deviations}. By contrast to the
Galton-Watson case, here random environments and the branching process can
conspire to achieve atypical events such as $Z_n \le e^{cn}$ when $c$ is
smaller than the typical geometric growth rate $\bar L$ and $ Z_n \ge e^{cn}$
when $c > \bar L$. One way to obtain such an atypical rate of growth is to have
a typical realization of the branching process in an atypical sequence of
environments. This gives us a general lower bound for the rate of decrease of
their probability. When each individual leaves at least one offspring in the
next generation almost surely, we compute the exact rate function of these
events and we show that conditionally on the large deviation event, the
trajectory $t \mapsto \frac1n \log Z_{[nt]}, t\in [0,1]$ converges to a
deterministic function $f_c :[0,1] \mapsto \R_+$ in probability in the sense of
the uniform norm. The most interesting case is when $c < \bar L$ and we
authorize individuals to have only one offspring in the next generation. In
this situation, conditionally on $Z_n \le e^{cn}$, the population size stays
fixed at 1 until a time $ \sim n t_c$. After time $n t_c$ an atypical sequence
of environments let $Z_n$ grow with the appropriate rate ($\neq \bar L$) to
reach $c.$ The corresponding map $f_c(t)$ is piecewise linear and is 0 on
$[0,t_c]$ and $f_c(t) = c(t-t_c)/(1-t_c)$ on $[t_c,1].$


title: Berry effect in acoustical polarization transport in phononic crystals

abstract:
  We derive the semiclassical equations of motion of a transverse acoustical
wave packet propagating in a phononic crystal subject to slowly varying
perturbations. The formalism gives rise to Berry effect terms in the equations
of motion, manifested as the Rytov polarization rotation law and the
polarization-dependent Hall effect. We show that the formalism is also
applicable to the case of non-periodic inhomogeneous media, yielding explicit
expressions for the Berry effect terms.


title: New completely regular q-ary codes based on Kronecker products

abstract:
  For any integer $\rho \geq 1$ and for any prime power q, the explicit
construction of a infinite family of completely regular (and completely
transitive) q-ary codes with d=3 and with covering radius $\rho$ is given. The
intersection array is also computed. Under the same conditions, the explicit
construction of an infinite family of q-ary uniformly packed codes (in the wide
sense) with covering radius $\rho$, which are not completely regular, is also
given. In both constructions the Kronecker product is the basic tool that has
been used.


title:
A new measurement of the antiproton-to-proton flux ratio up to 100 GeV
  in the cosmic radiation

abstract:
  A new measurement of the cosmic ray antiproton-to-proton flux ratio between 1
and 100 GeV is presented. The results were obtained with the PAMELA experiment,
which was launched into low-earth orbit on-board the Resurs-DK1 satellite on
June 15th 2006. During 500 days of data collection a total of about 1000
antiprotons have been identified, including 100 above an energy of 20 GeV. The
high-energy results are a ten-fold improvement in statistics with respect to
all previously published data. The data follow the trend expected from
secondary production calculations and significantly constrain contributions
from exotic sources, e.g. dark matter particle annihilations.


title: Observation of an anomalous positron abundance in the cosmic radiation

abstract:
  Positrons are known to be produced in interactions between cosmic-ray nuclei
and interstellar matter ("secondary production"). Positrons may, however, also
be created by dark matter particle annihilations in the galactic halo or in the
magnetospheres of near-by pulsars. The nature of dark matter is one of the most
prominent open questions in science today. An observation of positrons from
pulsars would open a new observation window on these sources. Here we present
results from the PAMELA satellite experiment on the positron abundance in the
cosmic radiation for the energy range 1.5 - 100 GeV. Our high energy data
deviate significantly from predictions of secondary production models, and may
constitute the first indirect evidence of dark matter particle annihilations,
or the first observation of positron production from near-by pulsars. We also
present evidence that solar activity significantly affects the abundance of
positrons at low energies.


title: Newton polyhedra of discriminants of projections

abstract:
  For a system of polynomial equations, whose coefficients depend on
parameters, the Newton polyhedron of its discriminant is computed in terms of
the Newton polyhedra of the coefficients. This leads to an explicit formula
(involving mixed fiber polyhedra and Euler obstructions of toric varieties) in
the unmixed case, suggests certain open questions in general, and generalizes a
number of similar known results. The argument is based on a formula for the
support function of a mixed fiber body, which also suggests a new proof for
existence of mixed fiber bodies.


title:
Feasibility of extracting a $\Sigma^-$ admixture probability in the
  neutron-rich $^{10}_{\Lambda}$Li hypernucleus

abstract:
  We examine theoretically production of the neutron-rich $^{10}_{\Lambda}$Li
hypernucleus by a double-charge exchange ($\pi^-$, $K^+$) reaction on a
$^{10}$B target with distorted-wave impulse approximation calculations. The
result shows that the magnitude and shape of the calculated spectrum at 1.20
GeV/c by a one-step mechanism $\pi^-p \to K^+ \Sigma^-$ via $\Sigma^-$ doorways
caused by a $\Sigma^-p \leftrightarrow \Lambda n$ coupling can explain the
recent experimental data, and the $\Sigma^-$ admixture probability in
$^{10}_{\Lambda}$Li is found to be the order of 10$^{-1}$ %. The ($\pi^-$,
$K^+$) reaction provides a capability of extracting properties of wave
functions with $\Lambda$-$\Sigma$ coupling effects in neutron-rich nuclei,
together with the reaction mechanism.


title: Automatic structures of bounded degree revisited

abstract:
  The first-order theory of a string automatic structure is known to be
decidable, but there are examples of string automatic structures with
nonelementary first-order theories. We prove that the first-order theory of a
string automatic structure of bounded degree is decidable in doubly exponential
space (for injective automatic presentations, this holds even uniformly). This
result is shown to be optimal since we also present a string automatic
structure of bounded degree whose first-order theory is hard for 2EXPSPACE. We
prove similar results also for tree automatic structures. These findings close
the gaps left open in a previous paper of the second author by improving both,
the lower and the upper bounds.


title: Supersymmetry and Gravitational Duality

abstract:
  We study how the supersymmetry algebra copes with gravitational duality. As a
playground, we consider a charged Taub-NUT solution of D=4, N=2 supergravity.
We find explicitly its Killing spinors, and the projection they obey provides
evidence that the dual magnetic momenta necessarily have to appear in the
supersymmetry algebra. The existence of such a modification is further
supported using an approach based on the Nester form. In the process, we find
new expressions for the dual magnetic momenta, including the NUT charge. The
same expressions are then rederived using gravitational duality.


title:
Cyclotomic double affine Hecke algebras and affine parabolic category O,
  I

abstract:
  Using the orbifold KZ connection we construct a functor from an affine
parabolic category O of type A to the category O of a cyclotomic rational
double affine Hecke algebra. We give several results concerning this functor.


title: Warped Wilson Line DBI Inflation

abstract:
  We propose a novel inflationary scenario in string theory in which the
inflaton field is a 'Wilson line' degree of freedom in the worldvolume of a
probe Dp-brane, in a warped flux compactification. Kinetic terms for Wilson
line fields on the world volume of a D-brane take a nonstandard
Dirac-Born-Infeld (DBI) form. Thus, we work in the framework of DBI inflation.
This extends the original slow roll Wilson line inflationary scenario, where
only the quadratic piece was considered. Warped DBI Wilson line inflation
offers an attractive alternative to ordinary (position field) DBI inflation,
inasmuch as observational and theoretical constraints get considerably relaxed.
Besides the standard large non-Gaussianities in DBI scenarios, it is also
possible to achieve an observable amount of gravitational waves.


title:
Origin of the narrow, single peak in the fission-fragment mass
  distribution for $^{258}$Fm

abstract:
  We discuss the origin of the narrowness of the single peak at mass-symmetric
division in the fragment mass-yield curve for spontaneous fission of
$^{258}$Fm. For this purpose, we employ the macroscopic-microscopic model, and
calculate a potential-energy curve at the mass-symmetric compact scission
configuration, as a function of the fragment mass number, which is obtained
from the single-particle wave-function densities. In the calculations, we
minimize total energies by varying the deformations of the two fragments, with
constraints on the mass quadrupole moment and keeping the neck radius zero, as
a function of mass asymmetry. Using the obtained potential, we solve the
one-dimensional Schr\"odinger equation with a microscopic coordinate-dependent
inertial mass to calculate the fragment mass-yield curve. The calculated mass
yield, expressed in terms of the microscopic mass density, is consistent with
the extremely narrow experimental mass distribution.