title:
Effects of quantized fields on the spacetime geometries of static
  spherically symmetric black holes

abstract:
  Analytic approximations for the stress-energy of quantized fields in the
Hartle-Hawking state in static black hole spacetimes predict divergences on the
event horizon of the black hole for a number of important cases. Such
divergences, if real, could substantially alter the spacetime geometry near the
event horizon, possibly preventing the black hole from existing. The results of
three investigations of these types of effects are presented. The first
involves a new analytic approximation for conformally invariant fields in
Reissner-Nordstrom spacetimes which is finite on the horizon. The second
focuses on the stress-energy of massless scalar fields in Schwarzschild-de
Sitter black holes. The third focuses on the stress-energy of massless scalar
fields in zero temperature black hole geometries that could be solutions to the
semiclassical backreaction equations near the event horizon of the black hole.


title: Obscuration in extremely luminous quasars

abstract:
  The spectral energy distributions and infrared (IR) spectra of a sample of
obscured AGNs selected in the mid-IR are modeled with recent clumpy torus
models to investigate the nature of the sources, the properties of the
obscuring matter, and dependencies on luminosity. The sample contains 21
obscured AGNs at z=1.3-3 discovered in the largest Spitzer surveys (SWIRE,
NDWFS, & FLS) by means of their extremely red IR to optical colors. All sources
show the 9.7micron silicate feature in absorption and have extreme mid-IR
luminosities (L(6micron)~10^46 erg/s). The IR SEDs and spectra of 12 sources
are well reproduced with a simple torus model, while the remaining 9 sources
require foreground extinction from a cold dust component to reproduce both the
depth of the silicate feature and the near-IR emission from hot dust. The
best-fit torus models show a broad range of inclinations, with no preference
for the edge-on torus expected in obscured AGNs. Based on the unobscured QSO
mid-IR luminosity function, and on a color-selected sample of obscured and
unobscured IR sources, we estimate the surface densities of obscured and
unobscured QSOs at L(6micron)>10^12 Lsun, and z=1.3-3.0 to be about 17-22
deg^-2, and 11.7 deg^-2, respectively. Overall we find that ~35-41% of luminous
QSOs are unobscured, 37-40% are obscured by the torus, and 23-25% are obscured
by a cold absorber detached from the torus. These fractions constrain the torus
half opening angle to be ~67 deg. This value is significantly larger than found
for FIR selected samples of AGN at lower luminosity (~46 deg), supporting the
receding torus scenario. A far-IR component is observed in 8 objects. The
estimated far-IR luminosities associated with this component all exceed
3.3x10^12 Lsun, implying SFRs of 600-3000 Msun/yr. (Abridged)


title:
Self-Equalization of Energies of Solitons in Transmission Systems by
  Guiding Filters

abstract:
  In this paper, the regulating effect of guiding filters on the energies of
solitons in wave-length division multiplexing (WDM) transmission systems is
rigorously studied. More precisely, it is shown that guiding filters prevent
the energies of solitons from decaying to zero in long distances. This goal is
achieved by studying a mathematical model of the evolution of energies of
solitons in transmission systems. The approach is mathematical and does not use
numerical or experimental results available in the literature; nevertheless, it
reaffirms such results.


title: Positive definite collections of disks

abstract:
  Let $Q(z,w)=-\prod_{k=1}^n [(z-a_k)(\bar{w}-\bar{a}_k)-R_k^2]$. M. Putinar
and B. Gustafsson proved recently that the matrix $Q(a_i,a_j)$, $1\leq i,j\leq
n$, is positive definite if disks $|z-a_i|<R_i$ form a disjoint collection. We
extend this result on symmetric collections of discs with overlapping. More
precisely, we show that in the case when the nodes $a_j$ are situated at the
vertices of a regular $n$-gon inscribed in the unit circle and $\forall i:
R_i\equiv R$, the matrix $Q(a_i,a_j)$ is positive definite if and only if
$R<\rho_n$, where $z=2\rho_n^2-1$ is the smallest $\ne-1$ zero of the Jacobi
polynomial $\mathcal{P}^{n-2\nu,-1}_\nu(z)$, $\nu=[n/2]$.


title:
Charged Current Neutrino Cross Section and Tau Energy Loss at Ultra-High
  Energies

abstract:
  We evaluate both the tau lepton energy loss produced by photonuclear
interactions and the neutrino charged current cross section at ultra-high
energies, relevant to neutrino bounds with Earth-skimming tau neutrinos, using
different theoretical and phenomenological models for nucleon and nucleus
structure functions. The theoretical uncertainty is estimated by taking
different extrapolations of the structure function F2 to very low values of x,
in the low and moderate Q2 range for the tau lepton interaction and at high Q2
for the neutrino-nucleus inelastic cross section. It is at these extremely low
values of x where nuclear shadowing and parton saturation effects are unknown
and could be stronger than usually considered. For tau and neutrino energies
E=10^9 GeV we find uncertainties of a factor 4 for the tau energy loss and of a
factor 2 for the charged current neutrino-nucleus cross section.


title:
Asymptotic stability of periodic solutions for nonsmooth differential
  equations with application to the nonsmooth van der Pol oscillator

abstract:
  In this paper we study the existence, uniqueness and asymptotic stability of
the periodic solutions for a Lipschitz system with a small right hand side.
Classical hypotheses in the periodic case of second Bogolyubov's theorem imply
our ones. By means of the results established we construct the curves of
dependence of the amplitude of asymptotically stable $2\pi$--periodic solutions
of the nonsmooth van der Pol oscillator on the detuning parameter and the
amplitude of the perturbation. After, we compare the resonance curves obtained,
with the resonance curves of the classical van der Pol oscillator which were
first constructed by Andronov and Witt.


title: XUV digital in-line holography using high-order harmonics

abstract:
  A step towards a successful implementation of timeresolved digital in-line
holography with extreme ultraviolet radiation is presented. Ultrashort XUV
pulses are produced as high-order harmonics of a femtosecond laser and a
Schwarzschild objective is used to focus harmonic radiation at 38 nm and to
produce a strongly divergent reference beam for holographic recording.
Experimental holograms of thin wires are recorded and the objects
reconstructed. Descriptions of the simulation and reconstruction theory and
algorithms are also given. Spatial resolution of few hundreds of nm is
potentially achievable, and micrometer resolution range is demonstrated.


title: Adaptive Investment Strategies For Periodic Environments

abstract:
  In this paper, we present an adaptive investment strategy for environments
with periodic returns on investment. In our approach, we consider an investment
model where the agent decides at every time step the proportion of wealth to
invest in a risky asset, keeping the rest of the budget in a risk-free asset.
Every investment is evaluated in the market via a stylized return on investment
function (RoI), which is modeled by a stochastic process with unknown
periodicities and levels of noise. For comparison reasons, we present two
reference strategies which represent the case of agents with zero-knowledge and
complete-knowledge of the dynamics of the returns. We consider also an
investment strategy based on technical analysis to forecast the next return by
fitting a trend line to previous received returns. To account for the
performance of the different strategies, we perform some computer experiments
to calculate the average budget that can be obtained with them over a certain
number of time steps. To assure for fair comparisons, we first tune the
parameters of each strategy. Afterwards, we compare the performance of these
strategies for RoIs with different periodicities and levels of noise.


title: Exchange moves and Fiedler polynomial

abstract:
  In order to obtain a Markov theorem without stabilization, Birman and Menasco
introduced the notion of exchange related braids. In this paper I study the way
the Fiedler polynomial distinguishes conjugacy classes of some particular
braided knots. I introduce the Kauffman bracket in the solid torus. Its Taylor
expansion give finite type invariants similar to the Fiedler polynomial. I
investigate how these invariants distinguish exchange related braids.


title: Serially Concatenated IRA Codes

abstract:
  We address the error floor problem of low-density parity check (LDPC) codes
on the binary-input additive white Gaussian noise (AWGN) channel, by
constructing a serially concatenated code consisting of two systematic
irregular repeat accumulate (IRA) component codes connected by an interleaver.
The interleaver is designed to prevent stopping-set error events in one of the
IRA codes from propagating into stopping set events of the other code.
Simulations with two 128-bit rate 0.707 IRA component codes show that the
proposed architecture achieves a much lower error floor at higher SNRs,
compared to a 16384-bit rate 1/2 IRA code, but incurs an SNR penalty of about 2
dB at low to medium SNRs. Experiments indicate that the SNR penalty can be
reduced at larger blocklengths.


title:
A Convex Stochastic Optimization Problem Arising from Portfolio
  Selection

abstract:
  A continuous-time financial portfolio selection model with expected utility
maximization typically boils down to solving a (static) convex stochastic
optimization problem in terms of the terminal wealth, with a budget constraint.
In literature the latter is solved by assuming {\it a priori} that the problem
is well-posed (i.e., the supremum value is finite) and a Lagrange multiplier
exists (and as a consequence the optimal solution is attainable). In this paper
it is first shown, via various counter-examples, neither of these two
assumptions needs to hold, and an optimal solution does not necessarily exist.
These anomalies in turn have important interpretations in and impacts on the
portfolio selection modeling and solutions. Relations among the non-existence
of the Lagrange multiplier, the ill-posedness of the problem, and the
non-attainability of an optimal solution are then investigated. Finally,
explicit and easily verifiable conditions are derived which lead to finding the
unique optimal solution.


title: Waveguiding power of photonic crystal slabs

abstract:
  We consider the waveguiding by thin patterned slabs embedded in a homogeneous
medium. In the longwave limit, the wave spectra of slabs are found to be well
described by a single frequency-independent parameter, which we call the
"guiding power". The guiding power can be evaluated in an effective medium
approximation, similar to the Maxwell Garnett theory, but modified for the
local field corrections specific to the two-dimensional geometry. The guiding
power is different for the transverse magnetic (TM) and transverse electric
(TE) polarizations. We show that the confinement factor of TM waves in a porous
layer with high index ratio can exceed that for a homogeneous layer. Similarly
enhanced confinement of TM waves is demonstrated for a layer of elongated
cylinders or elliptic inclusion with a high axis length ratio. The effect
originates from the suppression of local field effects and the increasing
internal field in the inclusion. It may be useful in the design of far-infrared
or THz quantum cascade lasers.


title: Embedding coproducts of partition lattices

abstract:
  We prove that the lattice Eq(X) of all equivalence relations on an infinite
set X contains, as a 0,1-sublattice, the 0-coproduct of two copies of itself,
thus answering a question by G.M. Bergman. Hence, by using methods initiated by
de Bruijn and further developed by Bergman, we obtain that Eq(X) also contains,
as a sublattice, the coproduct of 2^{card(X)} copies of itself.


title:
A multifrequency study of giant radio sources I. Low-frequency Giant
  Metrewave Radio Telescope observations of selected sources

abstract:
  We present low-frequency observations with the Giant Metrewave Radio
Telescope (GMRT) of a sample of giant radio sources (GRSs), and high-frequency
observations of three of these sources with the Very Large Array (VLA). From
multifrequency observations of the lobes we estimate the magnetic field
strengths using three different approaches, and show that these differ at most
by a factor of $\sim$3. For these large radio sources the inverse-Compton
losses usually dominate over synchrotron losses when estimates of the classical
minimum energy magnetic field are used, consistent with earlier studies.
However, this is often not true if the magnetic fields are close to the values
estimated using the formalism of Beck & Krause. We also examine the spectral
indices of the cores and any evidence of recurrent activity in these sources.
We probe the environment using the symmetry parameters of these sources and
suggest that their environments are often asymmetric on scales of $\sim$1 Mpc,
consistent with earlier studies.


title:
The chemical composition of planetary nebulae and HII regions in NGC
  3109

abstract:
  We present deep spectrophotometry for a sample of 8 PNe and 12 HII regions in
the irregular galaxy NGC 3109, to analyze the chemical composition of both
types of nebulae. We present line intensities and the physical conditions and
the abundances of He, O, Ne, N, S and Ar are derived, using the classical
T_e-based method. We confirm our previous identification of PNe and HII regions
based on photometry, except for one object that we argue is a compact HII
region rather than a PN. We find that the chemical composition of the ISM in
NGC 3109, as sampled by its HII regions, is remarkably uniform. The oxygen
abundance is log O/H + 12 = 7.77 \pm 0.07 in this galaxy, as compared to 8.05
\pm 0.09 for the SMC. PNe show significantly higher oxygen abundances in NGC
3109: log O/H + 12 = 8.16 \pm 0.19. We argue that, similarly to what has been
suggested for some of the PNe in the Magellanic Clouds and other metal-poor
galaxies, oxygen in the PNe in NGC 3109 is affected by dredge up in their
progenitors. This could be also the case for neon. From our analysis, we
conclude that these two elements are not always a safe indicator of the
chemical composition of the ISM at low metallicities. An alternative to the O
and Ne enrichment in PNe is that the low metallicity in HII regions has been
caused by dilution of the ISM due interaction with a neighbor galaxy about a
Gyr ago.
  The excitation patterns of the PNe in NGC 3109 are very different from the
excitation patterns of PNe in other galaxies. This would imply that the
evolution of PNe depends upon the properties of their progenitor stellar
populations, which vary from galaxy to galaxy. This should affect the PN
luminosity function and its use as a distance indicator.


title:
Algebraic structure of quasiradial solutions to the $\gamma$-harmonic
  equation

abstract:
  We obtain an explicit representation for quasiradial $\gamma$-harmonic
functions, which shows that these functions have essentially algebraic nature.
In particular, we give a complete description of all $\gamma$ which admit
algebraic quasiradial solutions. Unlike the cases $\gamma=\infty$ and
$\gamma=1$, only finitely many algebraic solutions is shown to exist for any
fixed $|\gamma|>1$. Moreover, there is a special extremal series of $\gamma $
which exactly corresponds to the well-known ideal $m$-atomic gas adiabatic
constant $\gamma=\frac{2m+3}{2m+1}$.


title: Interaction of ultrashort X-ray pulses with B4C, SiC and Si

abstract:
  The interaction of 32.5 and 6 nm ultrashort X-ray pulses with the solid
materials B4C, SiC and Si is simulated with a non-local thermodynamic
equilibrium (NLTE) radiation transfer code. We study the ionization dynamics as
function of depth in the material, modifications of the opacity during
irradiation and estimate crater depth. Furthermore, we compare the estimated
crater depth with experimental data, for fluences up to 2.2 J/cm2. Our results
show that at 32.5 nm irradiation, the opacity changes with less than a factor
of 2 for B4C and Si and a factor of 3 for SiC, for fluences up to 200 J/cm2. At
a laser wavelength of 6 nm, the model predicts a dramatic decrease in opacity
due to the weak inverse bremsstrahlung, increasing the crater depth for high
fluences.


title: Pionic transitions from X(3872) to chi_{cJ}

abstract:
  We consider transitions from the resonance X(3872) to the chi_{cJ} states of
charmonium with emission of one or two pions as a means of studying the
structure of the X resonance. We find that the relative rates for these
transitions to the final states with different J significantly depend on
whether the initial state is a pure charmonium state or a four-quark/molecular
state.


title:
Neel to Spin-Glass-like Phase Transition versus Dilution in
  Geometrically Frustrated ZnCr_{2-2x}Ga_{2x}O_4

abstract:
  ZnCr2O4 undergoes a first order spin-Peierls-like phase transition at 12.5 K
from a cubic spin liquid phase to a tetragonal Neel state. Using powder
diffraction and single crystal polarized neutron scattering, we determined the
complex spin structure of the Neel phase. This phase consisted of several
magnetic domains with different characteristic wave vectors. This indicates
that the tetragonal phase of ZnCr2O4 is very close to a critical point
surrounded by many different Neel states. We have also studied, using elastic
and inelastic neutron scattering techniques, the effect of nonmagnetic dilution
on magnetic correlations in ZnCr_{2-2x}Ga_{2x}O_4 (x=0.05 and 0.3). For x=0.05,
the magnetic correlations do not change qualitatively from those in the pure
material, except that the phase transition becomes second order. For x= 0.3,
the spin-spin correlations become short range. Interestingly, the spatial
correlations of the frozen spins in the x=0.3 material are the same as those of
the fluctuating moments in the pure and the weakly diluted materials.


title: Radio Continuum Jet in NGC 7479

abstract:
  The barred galaxy NGC 7479 hosts a remarkable jet-like radio continuum
feature: bright, 12-kpc long in projection, and hosting an aligned magnetic
field. The degree of polarization is 6%-8% along the jet, and remarkably
constant, which is consistent with helical field models. The radio brightness
of the jet suggests strong interaction with the ISM and hence a location near
the disk plane. We observed NGC 7479 at four wavelengths with the VLA and
Effelsberg radio telescopes. The equipartition strength is 35-40 micro-G for
the total and >10 micro-G for the ordered magnetic field in the jet. The jet
acts as a bright, polarized background. Faraday rotation between 3.5 and 6 cm
and depolarization between 6 and 22 cm can be explained by magneto-ionic gas in
front of the jet, with thermal electron densities of ~0.06 cm**(-3) in the bar
and ~0.03 cm**(-3) outside the bar. The regular magnetic field along the bar
points toward the nucleus on both sides. The regular field in the disk reveals
multiple reversals, probably consisting of field loops stretched by a shearing
gas flow in the bar. The projection of the jet bending in the sky plane is in
the sense opposite to that of the underlying stellar and gaseous spiral
structure. The bending in 3-D is most easily explained as a precessing jet,
with an age less than 10**6 years. Our observations are consistent with very
recent triggering, possibly by a minor merger. NGC 7479 provides a unique
opportunity to study interaction-triggered 15-kpc scale radio jets within a
spiral galaxy.


title:
Sneutrino cold dark matter, a new analysis: relic abundance and
  detection rates

abstract:
  We perform a new and updated analysis of sneutrinos as dark matter
candidates, in different classes of supersymmetric models. We extend previous
analyses by studying sneutrino phenomenology for full variations of the
supersymmetric parameters which define the various models. We first revisit the
standard Minimal Supersymmetric Standard Model, concluding that sneutrinos are
marginally compatible with existing experimental bounds, including direct
detection, provided they compose a subdominant component of dark matter. We
then study supersymmetric models with the inclusion of right-handed fields and
lepton-number violating terms. Simple versions of the lepton-number-violating
models do not lead to phenomenology different from the standard case when the
neutrino mass bounds are properly included. On the contrary, models with
right-handed fields are perfectly viable: they predict sneutrinos which are
compatible with the current direct detection sensitivities, both as subdominant
and dominant dark matter components. We also study the indirect detection
signals for such successful models: predictions for antiproton, antideuteron
and gamma-ray fluxes are provided and compared with existing and future
experimental sensitivities. The neutrino flux from the center of the Earth is
also analyzed.


title:
Finite Duration and Energy Effects in Lorentz-Violating Vacuum Cerenkov
  Radiation

abstract:
  Vacuum Cerenkov radiation is possible in certain Lorentz-violating quantum
field theories, when very energetic charges move faster than the phase speed of
light. In the presence of a CPT-even, Lorentz-violating modification of the
photon sector, the character of the Cerenkov process is controlled by the
high-frequency behavior of the radiation spectrum. The development of the
Cerenkov process can be markedly different, depending on whether the only
limits on the emission of very energetic photons come from energy-momentum
conservation or whether there are additional effects that cut off the spectrum
at high frequencies. Moreover, since the high-frequency cutoff determines the
total rate at which an emitting charge loses energy, it also controls all
aspects of the emission that are related to the process's finite duration.


title: Calibration Techniques for VERITAS

abstract:
  VERITAS is an array of four identical telescopes designed for detecting and
measuring astrophysical gamma rays with energies in excess of 100 GeV. Each
telescope uses a 12 m diameter reflector to collect Cherenkov light from air
showers initiated by incident gamma rays and direct it onto a `camera'
comprising 499 photomultiplier tubes read out by flash ADCs. We describe here
calibration methods used for determining the values of the parameters which are
necessary for converting the digitized PMT pulses to gamma-ray energies and
directions. Use of laser pulses to determine and monitor PMT gains is
discussed, as are measurements of the absolute throughput of the telescopes
using muon rings.


title:
The Structure of the Local Interstellar Medium IV: Dynamics, Morphology,
  Physical Properties, and Implications of Cloud-Cloud Interactions

abstract:
  We present an empirical dynamical model of the local interstellar medium
based on 270 radial-velocity measurements for 157 sight lines toward nearby
stars. Physical-parameter measurements (i.e., temperature, turbulent velocity,
depletions) are available for 90 components, or one-third of the sample,
enabling initial characterizations of the physical properties of LISM clouds.
The model includes 15 warm clouds located within 15 pc of the Sun, each with a
different velocity vector. We derive projected morphologies of all clouds and
estimate the volume filling factor of warm partially ionized material in the
LISM to be between ~5.5% and 19%. Relative velocities of potentially
interacting clouds are often supersonic, consistent with heating, turbulent,
and metal-depletion properties. Cloud-cloud collisions may be responsible for
the filamentary morphologies found in ~1/3 of LISM clouds, the distribution of
clouds along the boundaries of the two nearest clouds (LIC and G), the detailed
shape and heating of the Mic Cloud, the location of nearby radio scintillation
screens, and the location of a LISM cold cloud. Contrary to previous claims,
the Sun appears to be located in the transition zone between the LIC and G
Clouds.


title: Nonlinear thermal control in an N-terminal junction

abstract:
  We demonstrate control over heat flow in an N-terminal molecular junction.
Using simple model Hamiltonians we show that the heat current through two
terminals can be tuned, switched, and amplified, by the temperature and
coupling parameters of external gating reservoirs. We discuss two models: A
fully harmonic system, and a model incorporating anharmonic interactions. For
both models the control reservoirs induce thermal fluctuations of the
transition elements between molecular vibrational states. We find that a fully
harmonic model does not show any controllability, while for an anharmonic
system the conduction properties of the junction strongly depend on the
parameters of the gates. Realizations of the model system within nanodevices
and macromolecules are discussed.


title: Nearly Kaehler Reduction

abstract:
  We consider compactification of type IIA supergravity on nearly Kaehler
manifolds. These represent a simple class of SU(3) structure manifolds which
includes S^6 and CP^3. We exhibit for the first time an explicit reduction
ansatz in this context, obtaining an N=2 gauged supergravity in 4d with a
single vector and hypermultiplet. We verify that supersymmetric solutions of
the 4d theory lift to 10d solutions. Along the way, we discuss questions
related to encountering both electric and magnetic charges in the 4d theory.


title: Generalized Descents and Normality

abstract:
  We use Janson's dependency criterion to prove that the distribution of
$d$-descents of permutations of length $n$ converge to a normal distribution as
$n$ goes to infinity. We show that this remains true even if $d$ is allowed to
grow with $n$, up to a certain degree.


title:
Time-optimal synthesis of unitary transformations in coupled fast and
  slow qubit system

abstract:
  In this paper, we study time-optimal control problems related to system of
two coupled qubits where the time scales involved in performing unitary
transformations on each qubit are significantly different. In particular, we
address the case where unitary transformations produced by evolutions of the
coupling take much longer time as compared to the time required to produce
unitary transformations on the first qubit but much shorter time as compared to
the time to produce unitary transformations on the second qubit. We present a
canonical decomposition of SU(4) in terms of the subgroup SU(2)xSU(2)xU(1),
which is natural in understanding the time-optimal control problem of such a
coupled qubit system with significantly different time scales. A typical
setting involves dynamics of a coupled electron-nuclear spin system in pulsed
electron paramagnetic resonance experiments at high fields. Using the proposed
canonical decomposition, we give time-optimal control algorithms to synthesize
various unitary transformations of interest in coherent spectroscopy and
quantum information processing.


title: Rank of divisors on tropical curves

abstract:
  We investigate, using purely combinatorial methods, structural and
algorithmic properties of linear equivalence classes of divisors on tropical
curves. In particular, an elementary proof of the Riemann-Roch theorem for
tropical curves, similar to the recent proof of the Riemann-Roch theorem for
graphs by Baker and Norine, is presented. In addition, a conjecture of Baker
asserting that the rank of a divisor D on a (non-metric) graph is equal to the
rank of D on the corresponding metric graph is confirmed, and an algorithm for
computing the rank of a divisor on a tropical curve is constructed.


title: A Comment on the Infra-Red Problem in the AdS/CFT Correspondence

abstract:
  In this note we report on some recent progress in proving the AdS/CFT
correspondence for quantum fields using rigorously defined Euclidean path
integrals. We also comment on the infra-red problem in the AdS/CFT
correspondence and argue that it is different from the usual IR problem in
constructive quantum field theory. To illustrate this, a triviality proof based
on hypercontractivity estimates is given for the case of an ultra-violet
regularized potential of type $:\phi^4:$. We also give a brief discussion on
possible renormalization strategies and the specific problems that arise in
this context.


title:
Valence bond description of the long-range, nonfrustrated Heisenberg
  chain

abstract:
  The Heisenberg chain with antiferromagnetic, powerlaw exchange has a quantum
phase transition separating spin liquid and Neel ordered phases at a critical
value of the powerlaw exponent alpha. The behaviour of the system can be
explained rather simply in terms of a resonating valence bond state in which
the amplitude for a bond of length r goes as r^{-alpha} for alpha < 1, as
r^{-(1+alpha)/2} for 1 < alpha < 3, and as r^{-2} for alpha > 3. Numerical
evaluation of the staggered magnetic moment and Binder cumulant reveals a
second order transition at alpha_c = 2.18(5), in excellent agreement with
quantum Monte Carlo. The divergence of the magnetic correlation length is
consistent with an exponent nu = 2/(3-alpha_c) = 2.4(2).


title: Determining the Type, Redshift, and Age of a Supernova Spectrum

abstract:
  We present an algorithm to identify the type of an SN spectrum and to
determine its redshift and age. This algorithm, based on the correlation
techniques of Tonry & Davis, is implemented in the Supernova Identification
(SNID) code. It is used by members of ongoing high-redshift SN searches to
distinguish between type Ia and type Ib/c SNe, and to identify "peculiar" SNe
Ia. We develop a diagnostic to quantify the quality of a correlation between
the input and template spectra, which enables a formal evaluation of the
associated redshift error. Furthermore, by comparing the correlation redshifts
obtained using SNID with those determined from narrow lines in the SN host
galaxy spectrum, we show that accurate redshifts (with a typical error less
than 0.01) can be determined for SNe Ia without a spectrum of the host galaxy.
Last, the age of an input spectrum is determined with a typical 3-day accuracy,
shown here by using high-redshift SNe Ia with well-sampled light curves. The
success of the correlation technique confirms the similarity of some SNe Ia at
low and high redshifts. The SNID code, which is available to the community, can
also be used for comparative studies of SN spectra, as well as comparisons
between data and models.


title:
Theory of N\'eel and Valence-Bond-Solid Phases on the Kagome Lattice of
  Zn-paratacamite

abstract:
  Recently, neutron scattering data on powder samples of Zn-paratacamite,
Zn$_x$Cu$_{4-x}$(OH)$_6$Cl$_{2}$, with small Zn concentration has been
interpreted as evidence for valence bond solid and N\'eel ordering [1]. We
study the classical and quantum Heisenberg models on the distorted kagome
lattice appropriate for Zn-paratacamite at low Zn doping. Our theory naturally
leads to the emergence of the valence bond solid and collinear magnetic order
at zero temperature. Implications of our results to the existing experiments
are discussed. We also suggest future inelastic neutron and X-ray scattering
experiments that can test our predictions.


title: Amphiphile Adsorption on Rigid Polyelectrolytes

abstract:
  A theory is presented which quantitatively accounts for the cooperative
adsorption of cationic surfactants to anionic polyelectrolytes. For high salt
concentration we find that the critical adsorption concentration (CAC) is a
bilinear function of the polyion monomer and salt concentrations, with the
coefficients dependent only on the type of surfactant used. The results
presented in the paper might be useful for designing more efficient gene
delivery systems.


title: Evidence for a J/psi-ppbar Pauli Strong Coupling ?

abstract:
  The couplings of charmonia and charmonium hybrids (generically Psi) to ppbar
are of great interest in view of future plans to study these states using an
antiproton storage ring at GSI. These low to moderate energy Psi-ppbar
couplings are not well understood theoretically, and currently must be
determined from experiment. In this letter we note that the two independent
Dirac (gamma_mu) and Pauli (sigma_munu) ppbar couplings of the J/psi and psi'
can be constrained by the angular distribution of e+e- -> (J/psi, psi') ->
ppbar on resonance. A comparison of our theoretical results to recent
unpolarized data allows estimates of the ppbar couplings; in the better
determined J/psi case the data is inconsistent with a pure Dirac (gamma_mu)
coupling, and can be explained by the presence of a sigma_munu term. This Pauli
coupling may significantly affect the cross section of the PANDA process p pbar
-> pi0 J/psi near threshold. There is a phase ambiguity that makes it
impossible to uniquely determine the magnitudes and relative phase of the Dirac
and Pauli couplings from the unpolarized angular distributions alone; we show
in detail how this can be resolved through a study of the polarized reactions.


title: Fun with "Analysis I": basic theorems in calculus revisited

abstract:
  This note tries to show that a re-examination of a first course in analysis,
using the more sophisticated tools and approaches obtained in later stages, can
be a real fun for experts, advanced students, etc. We start by going to the
extreme, namely we present two proofs of the Extreme Value Theorem: "the
programmer proof" that suggests a method (which is practical in down-to-earth
settings) to approximate, to any required precision, the extreme values of the
given function in a metric space setting, and an abstract space proof ("the
level-set proof") for semicontinuous functions defined on compact topological
spaces. Next, in the intermediate part, we consider the Intermediate Value
Theorem, generalize it to a wide class of discontinuous functions, and
re-examine the meaning of the intermediate value property. The trek reaches the
final frontier when we discuss the Uniform Continuity Theorem, generalize it,
re-examine the meaning of uniform continuity, and find the optimal delta of the
given epsilon. Have fun!


title: Searching for Planetary Transits in Star Clusters

abstract:
  Star clusters provide an excellent opportunity to study the role of
environment on determining the frequencies of short period planets. They
provide a large sample of stars which can be imaged simultaneously, with a
common distance, age and pre-determined physical parameters. This allows the
search to be tailor-made for each specific cluster. Several groups are
attempting to detect transiting planets in open clusters. Three previous
surveys have also targeted the two brightest globular clusters. No cluster
survey has yet detected a planet. This contribution presents a brief overview
of the field, highlighting the pros and cons of performing such a search, and
presents the expected and current results, with implications for planetary
frequencies in regions of high stellar density and low metallicity.


title: Universal properties of large N phase transitions in Wilson loops

abstract:
  Numerical studies support the conjecture that in continuum planar QCD the
eigenvalue density of a Wilson loop operator undergoes a transition as the loop
is dilated while keeping the loop shape fixed. A second part of the conjecture
is that the transition obeys large N universality and that this universality
class is the same in 2, 3 and 4 Euclidean space-time dimensions. The focus of
the talk will be on clarifying precisely what the conjecture is claiming.


title: Some Generalizations of Fedorchuk Duality Theorem -- I

abstract:
  Generalizing Duality Theorem of V. V. Fedorchuk, we prove Stone-type duality
theorems for the following four categories: all of them have as objects the
locally compact Hausdorff spaces, and their morphisms are, respectively, the
continuous skeletal maps, the quasi-open perfect maps, the open maps, the open
perfect maps. In particular, a Stone-type duality theorem for the category of
all compact Hausdorff spaces and all open maps between them is proved. We also
obtain equivalence theorems for these four categories. The versions of these
theorems for the full subcategories of these categories having as objects all
locally compact connected Hausdorff spaces are formulated as well.


title:
How to form bulges/ellipticals in dark halos as fast as central black
  holes?

abstract:
  Gravity is nearly a universal constant in the cusp of an NFW galaxy halo.
Inside this external field an isothermal gas sphere will collapse and trigger a
starburst if above a critical central pressure. Thus formed spheroidal stellar
systems have Sersic-profile and satisfy the Faber-Jackson relation. The process
is consistent with observed starbursts. We also recover the M_BH vs. velocity
dispersion relation, if the gas collapse is regulated or resisted by the
feedback from radiation from the central BH.


title: The complexity of nonrepetitive edge coloring of graphs

abstract:
  A squarefree word is a sequence $w$ of symbols such that there are no strings
$x, y$, and $z$ for which $w=xyyz$. A nonrepetitive coloring of a graph is an
edge coloring in which the sequence of colors along any open path is
squarefree. We show that determining whether a graph $G$ has a nonrepetitive
$k$-coloring is $\Sigma_2^p$-complete. When we restrict to paths of lengths at
most $n$, the problem becomes NP-complete for fixed $n$.


title: Charged-Current Interaction Measurements in MiniBooNE

abstract:
  Neutrino oscillation is the only known phenomenon for physics beyond the
standard model. To investigate this phenomenon, the understanding of low energy
neutrino scattering (200<E<2000 MeV) is the crucial task for high energy
physicists. In this energy region, the charged current quasi-elastic (CCQE)
neutrino interaction is the dominant process, and experiments require a precise
model to predict signal samples. Using a high-statistics sample of muon
neutrino CCQE events, MiniBooNE finds that a simple Fermi gas model, with
appropriate adjustments, accurately characterizes the CCQE events on carbon.
The extracted parameters include an effective axial mass, MA=1.23 +- 0.20 GeV,
and a Pauli-blocking parameter, kappa = 1.019 +- 0.011.


title:
Metal-rich multi-phase gas in M87: AGN-driven metal transport,
  magnetic-field supported multi-temperature gas, and constraints on
  non-thermal emission observed with XMM-Newton

abstract:
  We use deep (~120 ks) XMM-Newton data of the M87 halo to analyze its
spatially resolved temperature structure and chemical composition. We focus
particularly on the regions of enhanced X-ray brightness associated with the
inner radio lobes, which are known not to be described very well by
single-temperature spectral models. Compared to a simple two-temperature fit,
we obtain a better and more physical description of the spectra using a model
that involves a continuous range of temperatures in each spatial bin. The range
of temperatures of the multiphase gas spans ~0.6-3.2 keV. Such a multiphase
structure is only possible if thermal conduction is suppressed by magnetic
fields. In the multi-temperature regions, we find a correlation between the
amount of gas cooler than the surrounding X-ray plasma and the metallicity, and
conclude that the cool gas is more metal-rich than the ambient halo. We
estimate the average Fe abundance of the cool gas to ~2.2 solar. Our results
thus point toward the key role of the active galactic nucleus (AGN) in
transporting heavy elements into the intracluster medium. The abundance ratios
of O/Si/S/Fe in and outside the X-ray arms are similar, indicating that the
dominant fraction of metals in the gas halo was uplifted by AGN outbursts
relatively recently compared to the age of M87. Our estimate for the mass of
the cool gas is 5e8 M_sun, which probably stems from a mixture of ICM, stellar
mass loss, and Type Ia supernova products. ~30-110 Myr are required to produce
the observed metals in the cool gas. Finally, we put upper limits on possible
non-thermal X-ray emission from M87 and, combining it with the 90 cm radio
maps, we put lower limits of around ~0.5-1.0 muG on the magnetic field
strength.


title: Community structure in directed networks

abstract:
  We consider the problem of finding communities or modules in directed
networks. The most common approach to this problem in the previous literature
has been simply to ignore edge direction and apply methods developed for
community discovery in undirected networks, but this approach discards
potentially useful information contained in the edge directions. Here we show
how the widely used benefit function known as modularity can be generalized in
a principled fashion to incorporate the information contained in edge
directions. This in turn allows us to find communities by maximizing the
modularity over possible divisions of a network, which we do using an algorithm
based on the eigenvectors of the corresponding modularity matrix. This method
is shown to give demonstrably better results than previous methods on a variety
of test networks, both real and computer-generated.


title: The Number of Periodic Orbits of a Rational Difference Equation

abstract:
  We show how a variant of the Lefschetz Fixed Point Theorem may be used to
count the number of periodic orbits for certain rational difference equations.


title:
Private Database Queries Using Quantum States with Limited Coherence
  Times

abstract:
  We describe a method for private database queries using exchange of quantum
states with bits encoded in mutually incompatible bases. For technology with
limited coherence time, the database vendor can announce the encoding after a
suitable delay to allow the user to privately learn one of two items in the
database without the ability to also definitely infer the second item. This
quantum approach also allows the user to choose to learn other functions of the
items, such as the exclusive-or of their bits, but not to gain more information
than equivalent to learning one item, on average. This method is especially
useful for items consisting of a few bits by avoiding the substantial overhead
of conventional cryptographic approaches.


title:
Developing and Researching PhET simulations for Teaching Quantum
  Mechanics

abstract:
  Quantum mechanics is difficult to learn because it is counterintuitive, hard
to visualize, mathematically challenging, and abstract. The Physics Education
Technology (PhET) Project, known for its interactive computer simulations for
teaching and learning physics, now includes 18 simulations on quantum mechanics
designed to improve learning of this difficult subject. Our simulations include
several key features to help students build mental models and intuitions about
quantum mechanics: visual representations of abstract concepts and microscopic
processes that cannot be directly observed, interactive environments that
directly couple students' actions to animations, connections to everyday life,
and efficient calculations so students can focus on the concepts rather than
the math. Like all PhET simulations, these are developed using the results of
education research and feedback from educators, and are tested in student
interviews and classroom studies. This article provides an overview of the PhET
quantum simulations and their development. We also describe research
demonstrating their effectiveness and share some insights about student
thinking that we have gained from our research on quantum simulations.


title: The H2 Amazing Life of NGC 6881

abstract:
  The H2 and optical (Ha, [NII]) morphology of NGC 6881 are very different.
Here we present a preliminary report of the analysis of new optical (Ha and
[NII]) and near-IR (Brg and H2) images and intermediate resolution JHK spectra
of this nebula. Our observations confirm the association of the H2 bipolar
lobes to NGC 6881 and reveal that H2 is predominantly shock excited in this
nebula. We conclude that NGC 6881 has multiple bipolar lobes that formed at
different phases of the nebular evolution and that the collimation conditions
or even the collimating agent changed from one ejection to the other.


title: The Solar Wind Around Pluto (SWAP) Instrument Aboard New Horizons

abstract:
  The Solar Wind Around Pluto (SWAP) instrument on New Horizons will measure
the interaction between the solar wind and ions created by atmospheric loss
from Pluto. These measurements provide a characterization of the total loss
rate and allow us to examine the complex plasma interactions at Pluto for the
first time. Constrained to fit within minimal resources, SWAP is optimized to
make plasma-ion measurements at all rotation angles as the New Horizons
spacecraft scans to image Pluto and Charon during the flyby. In order to meet
these unique requirements, we combined a cylindrically symmetric retarding
potential analyzer (RPA) with small deflectors, a top-hat analyzer, and a
redundant/coincidence detection scheme. This configuration allows for highly
sensitive measurements and a controllable energy passband at all scan angles of
the spacecraft.


title: Optimum Diversity-Multiplexing Tradeoff in the Multiple Relays Network

abstract:
  In this paper, a multiple-relay network in considered, in which $K$
single-antenna relays assist a single-antenna transmitter to communicate with a
single-antenna receiver in a half-duplex mode. A new Amplify and Forward (AF)
scheme is proposed for this network and is shown to achieve the optimum
diversity-multiplexing trade-off curve.


title:
Bose-Einstein correlations of pion pairs in central Pb+Pb collisions at
  CERN SPS energies

abstract:
  Measurements of Bose-Einstein correlations of pion pairs in central Pb+Pb
collisions were performed with the NA49 detector at the CERN SPS for beam
energies of 20A, 30A, 40A, 80A, and 158A GeV. Correlation functions were
measured in the longitudinally co-moving ``out-side-long'' reference frame as a
function of rapidity and transverse momentum in the forward hemisphere of the
reaction. Radius and correlation strength parameters were obtained from fits of
a Gaussian parametrization. The results show a decrease of the radius
parameters with increasing transverse momentum characteristic of strong radial
flow in the pion source. No striking dependence on pion-pair rapidity or beam
energy is observed. Static and dynamic properties of the pion source are
obtained from simultaneous fits with a blast-wave model to radius parameters
and midrapidity transverse momentum spectra. Predictions of hydrodynamic and
microscopic models of Pb+Pb collisions are discussed.


title:
The galaxy populations from the centers to the infall regions in z~0.25
  clusters

abstract:
  We conducted a panoramic spectroscopic campaign with MOSCA at the Calar Alto
observatory. We acquired spectra of more than 500 objects. Approximately 150 of
these spectra were of galaxies that are members of six different clusters,
which differ in intrinsic X-ray luminosity. The wavelength range allows us to
quantify the star formation activity by using the OII and the Halpha lines.
This activity is examined in terms of the large-scale environment expressed by
the clustercentric distance of the galaxies as well as on local scales given by
the spatial galaxy densities. A global suppression of star-formation is
detected in the outskirts of clusters, at about 3Rvir. Galaxies with ongoing
star-formation have similar activity, regardless of the environment. Therefore,
the decline of the star-formation activity inside the investigated clusters is
driven mainly by the significant change in the fraction of active versus
passive populations. This suggests that the suppression of the star-formation
activity occurs on short timescales. We detect a significant population of red
star-forming galaxies whose colors are consistent with the red-sequence of
passive galaxies. They appear to be in an intermediate evolutionary stage
between active and passive types. Since a suppression of star-formation
activity is measured at large clustercentric distances and low projected
densities, purely cluster-specific phenomena cannot fully explain the observed
trends. Therefore, as suggested by other studies, group preprocessing may play
an important role in transforming galaxies before they enter into the cluster
environment. Since models predict that a significant fraction of galaxies
observed in the outskirts may have already transversed through the cluster
center, the effects of ram-pressure stripping cannot be neglected. (ABRIDGED)


title: A recursion formula for k-Schur functions

abstract:
  The Bernstein operators allow to build recursively the Schur functions. We
present a recursion formula for k-Schur functions at t=1 based on combinatorial
operators that generalize the Bernstein operators. The recursion leads
immediately to a combinatorial interpretation for the expansion coefficients of
k-Schur functions at t=1 in terms of homogeneous symmetric functions.


title: Quantum characteristic classes and the Hofer metric

abstract:
  Given a closed monotone symplectic manifold $M$, we define certain
characteristic cohomology classes of the free loop space $L \text {Ham}(M,
\omega)$ with values in $QH_* (M)$, and their $S^1$ equivariant version. These
classes generalize the Seidel representation and satisfy versions of the axioms
for Chern classes. In particular there is a Whitney sum formula, which gives
rise to a graded ring homomorphism from the ring $H_{*} (L\text {Ham}(M,
\omega), \mathbb{Q})$, with its Pontryagin product to $QH_{2n+*} (M)$ with its
quantum product. As an application we prove an extension of a theorem of McDuff
and Slimowitz on minimality in the Hofer metric of a semifree Hamiltonian
circle action, to higher dimensional geometry of the loop space $L \text
{Ham}(M, \omega)$.


title: Seyfert's Sextet: A Slowly Dissolving Stephan's Quintet?

abstract:
  We present a multiwavelength study of the highly evolved compact galaxy group
known as Seyfert's Sextet (HCG79: SS). We interpret SS as a 2-3 Gyr more
evolved analog of Stephan's Quintet (HCG92: SQ). We postulate that SS formed by
sequential acquisition of 4-5 primarily late-type field galaxies. Four of the
five galaxies show an early-type morphology which is likely the result of
secular evolution driven by gas stripping. Stellar stripping has produced a
massive/luminous halo and embedded galaxies that are overluminous for their
size. These are interpreted as remnant bulges of the accreted spirals. H79d
could be interpreted as the most recent intruder being the only galaxy with an
intact ISM and uncertain evidence for tidal perturbation. In addition to
stripping activity we find evidence for past accretion events. H79b (NGC6027)
shows a strong counter-rotating emission line component interpreted as an
accreted dwarf spiral. H79a shows evidence for an infalling component of gas
representing feedback or possible cross fueling by H79d. The biggest challenge
to this scenario involves the low gas fraction in the group. If SS formed from
normal field spirals then much of the gas is missing. Finally, despite its
advanced stage of evolution, we find no evidence for major mergers and infer
that SS (and SQ) are telling us that such groups coalesce via slow dissolution.


title: X-ray Spectroscopy of the 2006 Outburst of RS Oph

abstract:
  We present the X-ray grating spectra of the recurrent nova RS Ophiuchi during
its 2006 outburst, obtained with the XMM-Newton and Chandra observatories. Two
weeks after optical maximum, the X-ray spectrum was hard and dominated by
emission lines of H-like and He-like ions. The X-ray luminosity was 2.4 x 10^36
erg s^-1 in the 0.33-10 keV range. The spectra indicate a collisionally
dominated plasma with a broad range of temperatures. All the lines are
blue-shifted, with the velocity shift increasing with lower ionization state
and longer wavelength. Two weeks later, the spectrum was still dominated by
emission lines, although the line ratios present indicate cooling. During this
observation, a soft X-ray flare occurred in which a new system of higher
velocity emission lines appeared in the soft end of the spectrum. The dominant
component during the third month was the supersoft continuum with the broad
absorption features of a hot white dwarf atmosphere. A preliminary model fit
indicates a white dwarf temperature slightly exceeding 800,000 K. The X-ray
luminosity reached at least 9 x 10^37 erg s^-1 in the 0.2-1 keV range, while
the intrinsic nebular absorption decreased by a factor of five since the first
observation. The spectral fits indicate a massive white dwarf, with a mass of
at least 1.2 M_\odot. Therefore, RS Oph may be an important type Ia supernova
progenitor. We show that the data are consistent with mass loss ending before
day 54 after the outburst, and nuclear burning ending around day 69. A rapid
decay in X-ray luminosity followed after week 10. The X-ray luminosity 5, 7 and
8 months after optical maximum dropped by more than two orders of magnitude.
The spectra do not appear to consistent with emission from an accretion disk.


title: Scheduling and Pre-Conditioning in Multi-User MIMO TDD Systems

abstract:
  The downlink transmission in multi-user multiple-input multiple-output (MIMO)
systems has been extensively studied from both communication-theoretic and
information-theoretic perspectives. Most of these papers assume
perfect/imperfect channel knowledge. In general, the problem of channel
training and estimation is studied separately. However, in interference-limited
communication systems with high mobility, this problem is tightly coupled with
the problem of maximizing throughput of the system. In this paper, scheduling
and pre-conditioning based schemes in the presence of reciprocal channel are
considered to address this. In the case of homogeneous users, a scheduling
scheme is proposed and an improved lower bound on the sum capacity is derived.
The problem of choosing training sequence length to maximize net throughput of
the system is studied. In the case of heterogeneous users, a modified
pre-conditioning method is proposed and an optimized pre-conditioning matrix is
derived. This method is combined with a scheduling scheme to further improve
net achievable weighted-sum rate.


title: An Improved Shashlyk Calorimeter

abstract:
  Shashlyk electromagnetic calorimeter modules with an energy resolution of
about 3%/sqrt{E (GeV)} for 50-1000 MeV photons has been developed, and a
prototype tested. Details of these improved modules, including mechanical
construction, selection of wave shifting fibers and photo-detectors, and
development of a new scintillator with improved optical and mechanical
properties are described. How the modules will perform in a large calorimeter
was determined from prototype measurements. The experimentally determined
characteristics of the calorimeter prototype show energy resolution of
sigma_E/E=(1.96+-0.1)% \oplus (2.74+-0.05)%/sqrt{E}, time resolution of sigma_T
= (72+-4)/sqrt{E} \oplus (14+-2)/E (ps), where photon energy E is given in GeV
units and \oplus means a quadratic summation. A punch-through inefficiency of
photon detection was measured to be \epsilon = 5*10^{-5} (\Theta >5 mrad).


title:
Nilpotent orbits in classical Lie algebras over $\textbf{F}_{2^n}$ and
  the Springer correspondence

abstract:
  We give the number of nilpotent orbits in the Lie algebras of orthogonal
groups under the adjoint action of the groups over $\tF_{2^n}$. Let $G$ be an
adjoint algebraic group of type $B,C$ or $D$ defined over an algebraically
closed field of characteristic 2. We construct the Springer correspondence for
the nilpotent variety in the Lie algebra of $G$.


title: Quantum formalism to describe binocular rivalry

abstract:
  On the basis of the general character and operation of the process of
perception, a formalism is sought to mathematically describe the subjective or
abstract/mental process of perception. It is shown that the formalism of
orthodox quantum theory of measurement, where the observer plays a key role, is
a broader mathematical foundation which can be adopted to describe the dynamics
of the subjective experience. The mathematical formalism describes the
psychophysical dynamics of the subjective or cognitive experience as
communicated to us by the subject. Subsequently, the formalism is used to
describe simple perception processes and, in particular, to describe the
probability distribution of dominance duration obtained from the testimony of
subjects experiencing binocular rivalry. Using this theory and parameters based
on known values of neuronal oscillation frequencies and firing rates, the
calculated probability distribution of dominance duration of rival states in
binocular rivalry under various conditions is found to be in good agreement
with available experimental data. This theory naturally explains an observed
marked increase in dominance duration in binocular rivalry upon periodic
interruption of stimulus and yields testable predictions for the distribution
of perceptual alteration in time.


title: Focal Plane Instrumentation of VERITAS

abstract:
  VERITAS is a new atmospheric Cherenkov imaging telescope array to detect very
high energy gamma rays above 100 GeV. The array is located in southern Arizona,
USA, at an altitude of 1268m above sea level. The array consists of four 12-m
telescopes of Davies-Cotton design and structurally resembling the Whipple 10-m
telescope. The four focal plane instruments are equipped with high-resolution
(499 pixels) fast photo-multiplier-tube (PMT) cameras covering a 3.5 degree
field of view with 0.15 degree pixel separation. Light concentrators reduce the
dead-space between PMTs to 25% and shield the PMTs from ambient light. The PMTs
are connected to high-speed preamplifiers allowing operation at modest anode
current and giving good single photoelectron peaks in situ. Electronics in the
focus box provides real-time monitoring of the anode currents for each pixel
and ambient environmental conditions. A charge injection subsystem installed in
the focus box allows daytime testing of the trigger and data acquisition system
by injecting pulses of variable amplitude and length directly into the
photomultiplier preamplifiers. A brief description of the full VERITAS focal
plane instrument is given in this paper.


title: Algebraic shifting of strongly edge decomposable spheres

abstract:
  Recently, Nevo introduced the notion of strongly edge decomposable spheres.
In this paper, we characterize the algebraic shifted complex of those spheres.
Algebraically, this result yields the characterization of the generic initial
ideal of the Stanley--Reisner ideal of Gorenstein* complexes having the strong
Lefschetz property in characteristic 0.


title: SUSY QCD Corrections to Associated Higgs-bottom Quark Production

abstract:
  The associated production of a Higgs boson with a b quark is a discovery mode
for an MSSM Higgs boson at large tan beta. We compute the SUSY QCD corrections
from gluino and squark loops to this process and combine them with the order
alpha_s^2 NLO QCD corrections to obtain reliable predictions for the rate.
Finally, we compare our results with an effective Lagrangian approximation
which includes only the low energy corrections from squark and gluino loops to
the b- bbar- Higgs vertices.


title:
Dependence of quantum correlations of twin beams on pump finesse of
  optical parametric oscillator

abstract:
  The dependence of quantum correlation of twin beams on the pump finesse of an
optical parametric oscillator is studied with a semi-classical analysis. It is
found that the phase-sum correlation of the output signal and idler beams from
an optical parametric oscillator operating above threshold depends on the
finesse of the pump field when the spurious pump phase noise generated inside
the optical cavity and the excess noise of the input pump field are involved in
the Langevin equations. The theoretical calculations can explain the previously
experimental results, quantitatively.


title: Do we need to know the temperature in prestellar cores?

abstract:
  Molecular line observations of starless (prestellar) cores combined with a
chemical evolution modeling and radiative transfer calculations are a powerful
tool to study the earliest stages of star formation. However, conclusions drawn
from such a modeling may noticeably depend on the assumed thermal structure of
the cores. The assumption of isothermality, which may work well in
chemo-dynamical studies, becomes a critical factor in molecular line formation
simulations. We argue that even small temperature variations, which are likely
to exist in starless cores, can have a non-negligible effect on the
interpretation of molecular line data and derived core properties. In
particular, ``chemically pristine'' isothermal cores (low depletion) can have
centrally peaked C$^{18}$O and C$^{34}$S radial intensity profiles, while
having ring-like intensity distributions in models with a colder center and/or
warmer envelope assuming the same underlying chemical structure. Therefore,
derived molecular abundances based on oversimplified thermal models may lead to
a mis-interpretation of the line data.


title:
Path Integral Quantization of Self Interacting Scalar Field with Higher
  Derivatives

abstract:
  Scalar field systems containing higher derivatives are studied and quantized
by Hamiltonian path integral formalism. A new point to previous quantization
methods is that field functions and their derivatives with time are considered
as independent canonical variables. Consequently, generating functional,
explicit expressions of propagators and Feynman diagrams in $\phi^3$ theory are
found


title: A note on lattices in semi-stable representations

abstract:
  Let p>2 be a prime, K a finite extension over Q_p and G :=Gal(\bar K/K). We
extend Kisin's theory on \phi-modules of finite E(u)-height to give a new
classification of G-stable Z_p-lattices in semi-stable representations


title:
Systematic study of trace radioactive impurities in candidate
  construction materials for EXO-200

abstract:
  The Enriched Xenon Observatory (EXO) will search for double beta decays of
136Xe. We report the results of a systematic study of trace concentrations of
radioactive impurities in a wide range of raw materials and finished parts
considered for use in the construction of EXO-200, the first stage of the EXO
experimental program. Analysis techniques employed, and described here, include
direct gamma counting, alpha counting, neutron activation analysis, and
high-sensitivity mass spectrometry.


title: A global DGLAP analysis of nuclear PDFs

abstract:
  In this talk, we shortly report results from our recent global DGLAP analysis
of nuclear parton distributions. This is an extension of our former
EKS98-analysis improved with an automated $\chi^2$ minimization procedure and
uncertainty estimates. Although our new analysis show no significant deviation
from EKS98, a sign of a significantly stronger gluon shadowing could be seen in
the RHIC BRAHMS data.


title:
Exploring the origin of neutron star magnetic field: magnetic properties
  of the progenitor OB stars

abstract:
  Ferrario & Wickramasinghe (2006) explored the hypothesis that the magnetic
fields of neutron stars are of fossil origin. In this context, they predicted
the field distribution of the progenitor OB stars, finding that 5 per cent of
main sequence massive stars should have fields in excess of 1kG. We have
carried out sensitive ESPaDOnS spectropolarimetric observations to search for
direct evidence of such fields in all massive B- and O-type stars in the Orion
Nebula Cluster star-forming region. We have detected unambiguous Stokes V
Zeeman signatures in spectra of three out of the eight stars observed (38%).
Using a new state-of-the-art Bayesian analysis, we infer the presence of strong
(kG), organised magnetic fields in their photospheres. For the remaining five
stars, we constrain any dipolar fields in the photosphere to be weaker than
about 200G. Statistically, the chance of finding three ~kG fields in a sample
of eight OB stars is quite low (less than 1%) if the predictions of Ferrario &
Wickramasinghe are correct. This implies that either the magnetic fields of
neutron stars are not of fossil origin, that the flux-evolution model of
Ferrario & Wickramasinghe is incomplete, or that the ONC has unusual magnetic
properties. We are undertaking a study of other young star clusters, in order
to better explore these possibilities.


title: Impurity resonance states in electron-doped high T_c superconductors

abstract:
  Two scenarios, i.e., the anisotropic s-wave pairing (the s-wave scenario) and
the d-wave pairing coexisting with antiferromagnetism (the coexisting scenario)
have been introduced to understand some of seemingly s-wave like behaviors in
electron doped cuprates. We considered the electronic structure in the presence
of a nonmagnetic impurity in the coexistence scenario. We found that even if
the AF order opens a full gap in quasi-particle excitation spectra, the mid-gap
resonant peaks in local density of states (LDoS) around an impurity can still
be observed in the presence of a d-wave pairing gap. The features of the
impurity states in the coexisting phase are markedly different from the pure AF
or pure d-wave pairing phases, showing the unique role of the coexisting AF and
d-wave pairing orders. On the other hand, it is known that in the pure s-wave
case no mid-gap states can be induced by a nonmagnetic impurity. Therefore we
proposed that the response to a nonmagnetic impurity can be used to
differentiate the two scenarios.


title: Quasi-Exactly Solvable Schr\"odinger Operators in Three Dimensions

abstract:
  The main contribution of our paper is to give a partial classification of the
quasi-exactly solvable Lie algebras of first order differential operators in
three variables, and to show how this can be applied to the construction of new
quasi-exactly solvable Schr\"odinger operators in three dimensions.


title: On the neighbor spacing of eigenvalues of unitary matrices

abstract:
  We describe a subtle error which can appear in numerical calculations
involving the spacing statistics of eigenvalues of random unitary matrices.


title:
Isotopic shift in angle-resolved photoemission spectra of Bi2Sr2CaCu2O8
  due to quadratic electron-phonon coupling

abstract:
  In connection with the experiment on oxygen isotope effect of Bi2Sr2CaCu2O8
with the angle-resolved photoemission spectroscopy (ARPES), we theoretically
study the isotope-induced band shift in ARPES by the Hartree-Fork and quantum
Monte Carlo methods. We find that this band shift can be clarified based on a
quadratically coupled electron-phonon (e-ph) model. The large ratio of band
shift versus phonon energy change is connected with the softening effect of
phonon, and the positive-negative sign change is due to the momentum dependence
of the e-ph coupling.


title:
A Problem with the Clustering of Recent Measures of the Distance to the
  Large Magellanic Cloud

abstract:
  The distance to the Large Magellanic Cloud (LMC) has long been of key
importance for the distance ladder and the distances to all galaxies, and as
such many groups have provided measurements of its distance modulus (\mu) with
many methods and various means of calibrating each method. Before the year
2001, the many measures spanned a wide range (roughly 18.1 < \mu < 18.8) with
the quoted error bars being substantially smaller than the spread, and hence
the consensus conclusion being that many of the measures had their
uncertainties being dominated by unrecognized systematic problems. In 2001, the
Hubble Space Telescope Key Project (HSTKP) on the distance scale made an
extensive analysis of earlier results and adopted the reasonable conclusion
that the distance modulus is 18.50+-0.10 mag, and the community has generally
accepted this widely popularized value. After 2002, 31 independent papers have
reported new distance measures to the LMC, and these cluster tightly around
\mu=18.50 mag. Indeed, these measures cluster too tightly around the HSTKP
value, with 68% of the measures being within 0.5-sigma of 18.50 mag. A
Kolmogorov-Smirnov test proves that this concentration deviates from the
expected Gaussian distribution at a >3-sigma probability level. This
concentration is a symptom of a worrisome problem. Interpretations considered
include correlations between papers, widespread over-estimation of error bars,
and band-wagon effects. This note is to alert workers in the field that this is
a serious problem that should be addressed.


title:
Low radio frequency signatures of ram pressure stripping in Virgo spiral
  NGC 4254

abstract:
  We report the detection of extended low radio frequency continuum emission
beyond the optical disk of the spiral galaxy NGC 4254 using the Giant Metrewave
Radio Telescope. NGC 4254, which has an almost face-on orientation, is located
in the outskirts of the Virgo cluster. Since such extended emission is uncommon
in low inclination galaxies, we believe it is a signature of magnetised plasma
pushed out of the disk by ram pressure of the intracluster medium as NGC 4254
falls into the Virgo cluster. The detailed spectral index distribution across
NGC 4254 shows that the steepest spectrum alpha < -1 (S propto nu^{alpha})
arises in the gas beyond the optical disk. This lends support to the ram
pressure scenario by indicating that the extended emission is not from the disk
gas but from matter which has been stripped by ram pressure. The steeper
spectrum of the extended emission is reminiscent of haloes in edge-on galaxies.
The sharp fall in intensity and enhanced polarization in the south of the
galaxy, in addition to enhanced star formation reported by others provide
evidence towards the efficacy of ram pressure on this galaxy. HI 21cm
observations show that the gas in the north lags in rotation and hence is
likely the atomic gas which is carried along with the wind. NGC 4254 is a
particularly strong radio emitter with a power of 7x10^{22} Watts/Hz at 240
MHz. We find that the integrated spectrum of the galaxy flattens at lower
frequencies and is well explained by an injection spectrum with
alpha_0=-0.45+-0.12. We end by comparing published simulation results with our
data and conclude that ram pressure stripping is likely to be a significant
contributor to evolution of galaxies residing in X-ray poor groups and cluster
outskirts.


title:
Some results on Gaussian Besov-Lipschitz spaces and Gaussian
  Triebel-Lizorkin spaces

abstract:
  In this paper we define Besov-Lipschitz and Triebel-Lizorkin spaces in the
context of Gaussian harmonic analysis, the harmonic analysis of Hermite
polynomial expansions. We study inclusion relations among them, some
interpolation results and continuity results of some important operators (the
Ornstein-Uhlenbeck and the Poisson-Hermite semigroups and the Bessel
potentials) on them. We also prove that the Gaussian Sobolev spaces
$L^p_\alpha(\gamma_d)$ are contained in them. The proofs are general enough to
allow extensions of these results to the case of Laguerre or Jacobi expansions
and even further in the general framework of diffusions semigroups.


abstract:
  In this paper we show that the Hausdorff dimension of the set of singular
pairs is 4/3. We also show that the action of diag(e^t,e^t,e^{-2t}) on
SL(3,R)/SL(3,Z) admits divergent trajectories that exit to infinity at
arbitrarily slow prescribed rates, answering a question of A.N. Starkov. As a
by-product of the analysis, we obtain a higher dimensional generalisation of
the basic inequalities satisfied by convergents of continued fractions. As an
illustration of the techniques used to compute Hausdorff dimension, we show
that the set of real numbers with divergent partial quotients has Hausdorff
dimension 1/2.


title: Prospects of a Search for a New Massless Neutral Gauge Boson at the ILC

abstract:
  Prospects to search for a new massless neutral gauge boson, the paraphoton,
in e+ e- collisions at center-of-mass energies of 0.5 and 1 TeV are studied.
The paraphoton naturally appears in models with abelian kinetic mixing. A
possible realistic model independent lowest order effective Lagrangian contains
magnetic interactions of the paraphoton with the Standard Model fermion fields.
These interactions are proportional to the fermion mass and grow with energy,
with however very weak paraphoton couplings to ordinary matter. At the ILC, a
potentially interesting process to search for the paraphoton is its radiation
off top quarks, so that the event topology to be searched for is a pair of
acoplanar top quark jets with missing energy. By combining many discriminating
features of signal and background events efficient paraphoton event selection
was achieved allowing to set limits for the top-paraphoton coupling. Arguments
in favor of the missing energy as the paraphoton with spin 1 are discussed.


title: Approximately Independent Features of Languages

abstract:
  To facilitate the testing of models for the evolution of languages, the
present note offers a set of linguistic features that are approximately
independent of each other. To find these features, the adjusted Rand index R'
is used to estimate the degree of pairwise relationship among 130 linguistic
features in a large published database. Many of the R' values prove to be near
0, as predicted for independent features, and a subset of 47 features is found
with an average R' of -0.0001. These 47 features are recommended for use in
statistical tests that require independent units of analysis.


title: On Polar Legendre Polynomials

abstract:
  We introduce a new class of polynomials $\{P_{n}\}$, that we call polar
Legendre polynomials, they appear as solutions of an inverse Gauss problem of
equilibrium position of a field of forces with $n+1$ unit masses. We study
algebraic, differential and asymptotic properties of this class of polynomials,
that are simultaneously orthogonal with respect to a differential operator and
a discrete-continuous Sobolev type inner product.


title: Gravitational Collapse in Higher Dimensional Husain Space-Time

abstract:
  We investigate exact solution in higher dimensional Husain model for a null
fluid source with pressure $p$ and density $\rho$ are related by the following
relations (i) $p=k\rho$, (ii) $p=k\rho-\frac{B(v)}{\rho^{\alpha}}$ (variable
modified Chaplygin) and (iii) $p=k\rho^{\alpha}$ (polytropic). We have studied
the nature of singularity in gravitational collapse for the above equations of
state and also for different choices of the of the parameters $k$ and $B$
namely, (i) $k=0$, $B=$ constant (generalized Chaplygin), (ii) $B=$ constant
(modified Chaplygin). It is found that the nature of singularity is independent
of these choices of different equation of state except for variable Chaplygin
model. Choices of various parameters are shown in tabular form. Finally,
matching of Szekeres model with exterior Husain space-time is done.


title: Distributed Quantum Computation Based-on Small Quantum Registers

abstract:
  We describe and analyze an efficient register-based hybrid quantum
computation scheme. Our scheme is based on probabilistic, heralded optical
connection among local five-qubit quantum registers. We assume high fidelity
local unitary operations within each register, but the error probability for
initialization, measurement, and entanglement generation can be very high
(~5%). We demonstrate that with a reasonable time overhead our scheme can
achieve deterministic non-local coupling gates between arbitrary two registers
with very high fidelity, limited only by the imperfections from the local
unitary operation. We estimate the clock cycle and the effective error
probability for implementation of quantum registers with ion-traps or
nitrogen-vacancy (NV) centers. Our new scheme capitalizes on a new efficient
two-level pumping scheme that in principle can create Bell pairs with
arbitrarily high fidelity. We introduce a Markov chain model to study the
stochastic process of entanglement pumping and map it to a deterministic
process. Finally we discuss requirements for achieving fault-tolerant operation
with our register-based hybrid scheme, and also present an alternative approach
to fault-tolerant preparation of GHZ states.


title:
Factorized domain wall partition functions in trigonometric vertex
  models

abstract:
  We obtain factorized domain wall partition functions for two sets of
trigonometric vertex models: 1. The N-state Deguchi-Akutsu models, for N = {2,
3, 4} (and conjecture the result for all N >= 5), and 2. The sl(r+1|s+1)
Perk-Schultz models, for {r, s = \N}, where (given the symmetries of these
models) the result is independent of {r, s}.


title:
Quasi-Spherical Gravitational Collapse in higher dimension and the
  effect of equation of state

abstract:
  Gravitational collapse in (n+2) dimensional quasi-spherical space-time is
studied for a fluid with non vanishing radial pressure. An exact analytic
solution is obtained (ignoring the arbitrary integration function) for the
equation of state $p_{r}=(\gamma-1)\rho.$ The singularity is studied locally by
comparing the time of formation of apparent horizon and the central shell
focusing singularity while the global nature of the final fate of collapse is
characterized by the existence of radial null geodesic. It is revealed that the
end state of collapse for D dimension with equation of state $p=-\rho$, for
(D$-$1) dimensional dust and (D$-$2)dimension with equation of state $p=\rho$
are identical.


title:
Real-time observation of polyelectrolyte-induced binding of charged
  bilayers

abstract:
  We present real-time observations by confocal microscopy of the dynamic
behavior of multilamellar vesicles (MLVs), composed of charged synthetic
lipids, when put in contact with oppositely charged polyelectrolyte (PE)
molecules. We find that the MLVs exhibit astonishing morphological transitions,
which result from the discrete and progressive binding of the charged bilayers
induced by a high PE concentration gradient. Our physical picture is confirmed
by quantitative measurements of the fluorescence intensity as the bilayers bind
to each other. The shape transitions lead eventually to the spontaneous
formation of hollow capsules, whose thick walls are composed of lipid
multilayers condensed with PE molecules. This class of objects may have some
(bio)technological applications.


title: Piecewise linear density estimation for sampled data

abstract:
  Nonparametric density estimation is considered for a discretely observed
stationary continuous-time process. For each of three given time sampling
procedures either random or deterministic, we establish that histograms and
frequency polygons can reach the same optimal $L_{2}$-rates as in the
independent and identically distributed case. Moreover, thanks to a suitable
"high frequency" sampling design, these rates are derived together with a
minimized time of observation depending on the regularity of sample paths.


title: A class of finite simple Bol loops of exponent 2

abstract:
  In this paper we give an infinite class of finite simple right Bol loops of
exponent 2. The right multiplication group of these loops is an extension of an
elementary Abelian 2-group by $S_5$. The construction uses the description of
the structure of such loops given by M. Aschbacher. These results answer some
questions of M. Aschbacher.


title:
Post common envelope binaries from SDSS. II: Identification of 9 close
  binaries with VLT/FORS2

abstract:
  The Sloan Digital Sky Survey turned out to be very efficient in identifying
white dwarf/main sequence binaries (WDMS). The population of WDMS systems
consists of wide systems whose stellar components evolve like single stars and
- more interesting in the context of close binary evolution - PCEBs. We pursue
a large-scale follow-up survey to identify and characterise the PCEBs among the
WDMS binaries that have been found with SDSS. We use a two-step strategy with
the identification of PCEBs among WDMS in the first and orbital period
determinations in the second phase. Here we present first results of our
VLT/FORS2 pilot-study that has the target of identifying the PCEBs among the
fainter (g>~18.5) SDSS-WDMS. From published SDSS catalogues we selected 26 WDMS
targets to be observed with VLT/FORS2. Using a spectral decomposition/fitting
technique we determined the white dwarf effective temperatures and surface
gravities, masses, and secondary star spectral types for all WDMS in our
sample. We used the NaI 8183.27,8194.81 doublet to measure radial velocity
variations of our targets and performed additional follow-up spectroscopy using
Magellan-Clay/LDSS3 of two systems showing significant radial velocity
variations. Among the 26 WDMS systems we find 9 strong PCEB candidates showing
clear (>=3sigma) radial velocity variations and we estimate the fraction of
PCEBs among SDSS WDMS to be ~35%. We find indications for a dependence of the
relative number of PCEBs among SDSS-WDMS on the spectral type of the secondary
star. These results are subject to small number statistics and need to be
confirmed by additional observations. For two of the identified PCEB
candidates, SDSSJ1047+0523 and SDSSJ1414-0132, we measured the orbital periods
to be 9.17hrs and 17.48hrs respectively.


title: On harmonic quasiconformal quasi-isometries

abstract:
  The purpose of this paper is to explore conditions which guarantee
Lipschitz-continuity of harmonic maps w.r.t. quasihyperbolic metrics. For
instance, we prove that harmonic quasiconformal maps are Lipschitz w.r.t.
quasihyperbolic metrics.


title: Probe into the interior of compact stars

abstract:
  The interior of neutron stars contains nuclear matter at very high density
for numerous subatomic particles compete with each other. Therefore, confirming
the components and properties there is our significant task. Here we summarize
the possible methods especial the way of r-mode instability to probe into the
neutron star and show our some results. The KHz pulsar in XTE J1739-285 may
give a significant implication


title: Three episodes of jet activity in the FRII radio galaxy B0925+420

abstract:
  We present Very Large Array images of a "Double-Double Radio Galaxy", a class
of objects in which two pairs of lobes are aligned either side of the nucleus.
In this object, B0925+420, we discover a third pair of lobes, close to the core
and again in alignment with the other lobes. This first-known "Triple-Double"
object strongly increases the likelihood that these lobes represent mutiple
episodes of jet activity, as opposed to knots in an underlying jet. We model
the lobes in terms of their dynamical evolution. We find that the inner pair of
lobes is consistent with the outer pair having been displaced buoyantly by the
ambient medium. The middle pair of lobes is more problematic - to the extent
where an alternative model interpreting the middle and inner "lobes" as
additional bow shocks within the outer lobes may be more appropriate - and we
discuss the implications of this on our understanding of the density of the
ambient medium.


title: Higgs mechanism in five-dimensional gauge theories

abstract:
  Lattice simulations of five-dimensional gauge theories on an orbifold
revealed that there is spontaneous symmetry breaking. Some of the
extra-dimensional components of the gauge field play the role of a Higgs field
and some of the four-dimensional components become massive gauge bosons. The
effect is confirmed by computing the Coleman-Weinberg potential with a cutoff.
We compare the results of this computation with the lattice data.


title:
Strong coupling analysis of QED$_3$ for excitation spectrum broadening
  in undoped high-temperature superconductor

abstract:
  Theory of quantum electrodynamics in three spatial-time dimension is applied
to the two-dimensional $S=1/2$ quantum Heisenberg antiferromagnet in order to
investigate a doped hole in high-temperature superconductors. Strong coupling
analysis of the U(1) gauge field interaction is carried out to describe
spectral broadening observed in the undoped compounds. It is found that the
fermionic quasiparticle spectrum is of Gaussian form with the width about 3J,
with J being the superexchange interaction energy. The energy shift of the
spectrum is on the order of the quasiparticle band width, which suggests that
the system is in the strong coupling regime with respect to the gauge field
interaction describing the phase fluctuations about the staggered flux state.


title: A Near-Infrared Stellar Spectral Library: III. J-Band Spectra

abstract:
  This paper is the third in the series of papers published on near-infrared
(NIR) stellar spectral library by Ranade et al. (2004 & 2007). The observations
were carried out with 1.2 meter Gurushikhar Infrared Telescope (GIRT), at Mt.
Abu, India using a NICMOS3 HgCdTe $256 \times 256$ NIR array based
spectrometer. In paper I (Ranade et al. 2004), H-band spectra of 135 stars at a
resolution of $\sim 16$\AA & paper II (Ranade et al. 2007), K band spectra of
114 stars at a resolution of $\sim 22$\AA were presented. The J-band library
being released now consists of 126 stars covering spectral types O5--M8 and
luminosity classes I--V. The spectra have a moderate resolution of $\sim
12.5$\AA in the J band and have been continuum shape corrected to their
respective effective temperatures. The complete set of library in near-infrared
(NIR) will serve as a good database for researchers working in the field of
stellar population synthesis. The complete library in J, H & K is available
online at: http://vo.iucaa.ernet.in/$\sim$voi/NIR\_Header.html


title: Distributed N-body Simulation on the Grid Using Dedicated Hardware

abstract:
  We present performance measurements of direct gravitational N -body
simulation on the grid, with and without specialized (GRAPE-6) hardware. Our
inter-continental virtual organization consists of three sites, one in Tokyo,
one in Philadelphia and one in Amsterdam. We run simulations with up to 196608
particles for a variety of topologies. In many cases, high performance
simulations over the entire planet are dominated by network bandwidth rather
than latency. With this global grid of GRAPEs our calculation time remains
dominated by communication over the entire range of N, which was limited due to
the use of three sites. Increasing the number of particles will result in a
more efficient execution. Based on these timings we construct and calibrate a
model to predict the performance of our simulation on any grid infrastructure
with or without GRAPE. We apply this model to predict the simulation
performance on the Netherlands DAS-3 wide area computer. Equipping the DAS-3
with GRAPE-6Af hardware would achieve break-even between calculation and
communication at a few million particles, resulting in a compute time of just
over ten hours for 1 N -body time unit. Key words: high-performance computing,
grid, N-body simulation, performance modelling


title:
Microwave power generated by a spin-torque oscillator in the presence of
  noise

abstract:
  An expression for the microwave power generated by a spin-torque oscillator
in the presence of thermal noise is derived. This expression, when used in a
subcritical regime, demonstrates that generated power is determined by the
noise level and provides a simple way to experimentally determine the threshold
current for microwave generation. The same expression gives a good quantitative
description of the experimentally measured dependence of the generated power on
the bias current in a moderate super-critical range of bias current variation.


title: Feshbach resonances in mixtures of ultracold $^6$Li and $^{87}$Rb gases

abstract:
  We report on the observation of two Feshbach resonances in collisions between
ultracold $^6$Li and $^{87}$Rb atoms in their respective hyperfine ground
states $|F,m_F>=|1/2,1/2>$ and $|1,1>$. The resonances show up as trap losses
for the $^6$Li cloud induced by inelastic Li-Rb-Rb three-body collisions. The
magnetic field values where they occur represent important benchmarks for an
accurate determination of the interspecies interaction potentials. A broad
Feshbach resonance located at 1066.92 G opens interesting prospects for the
creation of ultracold heteronuclear molecules. We furthermore observe a strong
enhancement of the narrow p-wave Feshbach resonance in collisions of $^6$Li
atoms at 158.55 G in the presence of a dense $^{87}$Rb cloud. The effect of the
$^{87}$Rb cloud is to introduce Li-Li-Rb three-body collisions occurring at a
higher rate than Li-Li-Li collisions.


title:
Branching Fractions and Direct CP Asymmetries of Charmless B Decay Modes
  at CDF

abstract:
  We present new CDF results on the branching fractions and time-integrated
direct CP asymmetries for $B^0$ and $B^0_s$ decay modes into pairs of charmless
charged hadrons (pions or kaons). The data-set for this update amounts to 1
$\mathrm{fb}^{-1}$ of $p\bar p$ collisions at a center of mass energy 1.96
$\mathrm{TeV}$. We report the first observation of the $B_s \to K^- \pi^+$ mode
and a measurement of its branching fraction and direct CP asymmetry. We also
observe for the first time two charmless decays of the $\Lambda_b^0$-baryon:
$\Lambda_b^0 \to p\pi^-$ and $\Lambda_b^0 \to pK^-$.


title:
Charge-to-spin conversion of electron entanglement states and
  spin-interaction-free solid-state quantum computation

abstract:
  Without resorting to spin-spin coupling, we propose a scalable spin quantum
computing scheme assisted with a semiconductor multiple-quantum-dot structure.
The techniques of single electron transitions and the nanostructure of
quantum-dot cellular automata (QCA) are used to generate charge entangled
states of two electrons, which are then converted into spin entanglement states
using single-spin rotations only. Deterministic two-qubit quantum gates are
also manipulated using only single-spin rotations with the help of QCA. A
single-shot readout of spin states can be carried out by coupling the multiple
dot structure to a quantum point contact. As a result, deterministic
spin-interaction-free quantum computing can be implemented in semiconductor
nanostructure.


title: A diffusion Monte Carlo study of small para-Hydrogen clusters

abstract:
  Ground state energies and chemical potentials of parahydrogen clusters are
calculated from 3 to 40 molecules using the diffusion Monte Carlo technique
with two different pH2-pH2 interactions. This calculation improves a previous
one by the inclusion of three-body correlations in the importance sampling, by
the time step adjustement and by a better estimation of the statistical errors.
Apart from the cluster with 13 molecules, no other magic clusters are
predicted, in contrast with path integral Monte Carlo results.


title:
Practical Multiwriter Lock-Free Queues for "Hard Real-Time" Systems
  without CAS

abstract:
  FIFO queues with a single reader and writer can be insufficient for "hard
real-time" systems where interrupt handlers require wait-free guarantees when
writing to message queues. We present an algorithm which elegantly and
practically solves this problem on small processors that are often found in
embedded systems. The algorithm does not require special CPU instructions (such
as atomic CAS), and therefore is more robust than many existing methods that
suffer the ABA problem associated with swing pointers. The algorithm gives
"first-in, almost first-out" guarantees under pathological interrupt
conditions, which manifests as arbitrary "shoving" among nearly-simultaneous
arrivals at the end of the queue.


title: A model for the orbifold Chow ring of weighted projective spaces

abstract:
  We construct an isomorphism of graded Frobenius algebras between the orbifold
Chow ring of weighted projective spaces and graded algebras of groups of roots
of the unity.


title: The distant galaxy cluster CL0016+16: X-ray analysis up to $R_{200}$

abstract:
  To study the mass distribution of galaxy clusters up to their Virial radius,
CL0016+16 seems to be a good candidate,since it is a bright massive cluster,
previously considered as being dynamically relaxed. Using XMM-Newton
observations of CL0016+16, we performed a careful X-ray background analysis,
and we detected convincingly its X-ray emission up to $R_{200}$. We then
studied its dynamical state with a detailed 2D temperature and surface
brightness analysis of the inner part of the cluster. Using the assumption of
both spherical symmetry and hydrostatic equilibrium (HE) we can determine the
main cluster parameters: total mass, temperature profile, surface brightness
profile and $\beta$-parameter. We also build a temperature map which clearly
exhibits departure from spherical symmetry in the centre. To estimate the
influence of these perturbations onto our total mass estimate, we also compute
the total mass in the framework of the HE approach, but this time with various
temperature profiles obtained in different directions. These various total mass
estimates are consistent with each other. The temperature perturbations are
clear signatures of ongoing merger activity. We also find significant residuals
after subtracting the emissivity map by a 2D $\beta$-model fit. We conclude
that, although CL0016+16 shows clear signs of merger activity and departure
from spherical symmetry in the centre, its X-ray emissivity can be detected up
to $R_{200}$ and the corresponding mass $M_{200}$ can be computed directly. It
is therefore a good candidate to study cosmological scaling laws as predicted
by the theory.


title: Semi-Classical Dynamics in Quantum Spin Systems

abstract:
  We consider two limiting regimes, the large-spin and the mean-field limit,
for the dynamical evolution of quantum spin systems. We prove that, in these
limits, the time evolution of a class of quantum spin systems is determined by
a corresponding Hamiltonian dynamics of classical spins. This result can be
viewed as a Egorov-type theorem. We extend our results to the thermodynamic
limit of lattice spin systems and continuum domains of infinite size, and we
study the time evolution of coherent spin states in these limiting regimes.


title: A hydrodynamic scheme for two-component winds from hot stars

abstract:
  We have developed a time-dependent two-component hydrodynamics code to
simulate radiatively-driven stellar winds from hot stars. We use a
time-explicit van Leer scheme to solve the hydrodynamic equations of a
two-component stellar wind. Dynamical friction due to Coulomb collisions
between the passive bulk plasma and the line-scattering ions is treated by a
time-implicit, semi-analytic method using a polynomial fit to the Chandrasekhar
function. This gives stable results despite the stiffness of the problem. This
method was applied to model stars with winds that are both poorly and
well-coupled. While for the former case we reproduce the mCAK solution, for the
latter case our solution leads to wind decoupling.


title: Systematic generation of entanglement measures for pure states

abstract:
  We propose a method to generate entanglement measures systematically by using
the irreducible decomposition of some copies of a state under the local unitary
(LU) transformations. It is applicable to general multipartite systems. We show
that there are entanglement monotones corresponding to singlet representations
of the LU group. They can be evaluated efficiently in an algebraic way, and
experimentally measurable by local projective measurements of the copies of the
state. Non-singlet representations are also shown to be useful to classify
entanglement. Our method reproduces many well-known measures in a unified way,
and produces also a lot of new ones.


title: Neutral mesons and disconnected diagrams in Twisted Mass QCD

abstract:
  We evaluate properties of neutral mesons in Nf=2 dynamical simulations of
TMQCD at maximal twist. The pion is explored - establishing the size of the
isospin splitting (an order a^2 effect). We investigate the eta' (the Nf=2
flavour singlet pseudoscalar meson) and neutral rho and scalar mesons. We show
that disconnected diagrams can be evaluated very efficiently in TMQCD using
variance reduction methods.


title: Topological Dynamics of 2D Cellular Automata

abstract:
  Topological dynamics of cellular automata (CA), inherited from classical
dynamical systems theory, has been essentially studied in dimension 1. This
paper focuses on 2D CA and aims at showing that the situation is different and
more complex. The main results are the existence of non sensitive CA without
equicontinuous points, the non-recursivity of sensitivity constants and the
existence of CA having only non-recursive equicontinuous points. They all show
a difference between the 1D and the 2D case. Thanks to these new constructions,
we also extend undecidability results concerning topological classification
previously obtained in the 1D case.


title:
Experimental proton-proton correlation function derived for the pp ->
  ppeta reaction

abstract:
  Based on the high statistics data from the pp -> ppX reaction measured by the
COSY-11 collaboration [1] we have derived a two-proton correlation function for
the production of the ppeta and pp+pions systems. The measured correlation
function normalized to the value simulated for a point-like source was compared
with a theoretical prediction in order to estimate the size of the reaction
volume.