title:
On the fundamental solution of an elliptic equation in nondivergence
  form

abstract:
  We consider the existence and asymptotics for the fundamental solution of an
elliptic operator in nondivergence form, ${\mathcal
L}(x,\del_x)=a_{ij}(x)\del_i\del_i$, for $n\geq 3$. We assume that the
coefficients have modulus of continuity satisfying the square Dini condition.
For fixed $y$, we construct a solution of ${\mathcal L}Z_y(x)=0$ for
$0<|x-y|<\e$ with explicit leading order term which is
$O(|x-y|^{2-n}e^{I(x,y)})$ as $x\to y$, where $I(x,y)$ is given by an integral
and plays an important role for the fundamental solution: if $I(x,y)$
approaches a finite limit as $x\to y$, then we can solve ${\mathcal
L}(x,\del_x)F(x,y)=\de(x-y)$, and $F(x,y)$ is asymptotic as $x\to y$ to the
fundamental solution for the constant coefficient operator ${\mathcal
L}(y,\del_x)$. On the other hand, if $I(x,y)\to -\infty$ as $x\to y$ then the
solution $Z_y(x)$ violates the "extended maximum principle" of Gilbarg & Serrin
\cite{GS} and is a distributional solution of ${\mathcal L}(x,\del_x)Z_y(x)=0$
for $|x-y|<\e$ although $Z_y$ is not even bounded as $x\to y$.


title: $\alpha$-vacuum and inflationary bispectrum

abstract:
  In this paper, we discuss the non-Guassianity originated from the
$\alpha$-vacuum on the CMB anisotropy. For $\alpha$-vacuum, there exist
correlation between points in the acausal two patches of de Sitter spactime.
Such kind of correlation can lead to large local form non-Guassianity in
$\alpha$-vacuum. For the single field slow-roll inflationary scenario, the
spacetime is in a quasi-de Sitter phase during the inflation. We will show that
the $\alpha$-vacuum in this case will lead to non-Gaussianity with
distinguished feature, of a large local form and a very different shape.


title:
Formulation of Time-Resolved Counting Statistics Based on a
  Positive-Operator-Valued Measure

abstract:
  We propose a derivation of the full counting statistics of electronic current
based on a positive-operator-valued measure. Our approach justifies the
Levitov-Lesovik formula in the long-time limit, but can be generalized to the
detection of finite-frequency noise correlations. The combined action of the
projection postulate and the quantum formula for current noise at high
frequencies imply an additional white noise. Estimates for this additional
noise are in accordance with known experiments. We propose an experimental test
of our conjecture by a simultaneous measurement of high- and low-frequency
noise.


title: Topological complexity of configuration spaces

abstract:
  The topological complexity TC(X) is a homotopy invariant which reflects the
complexity of the problem of constructing a motion planning algorithm in the
space X, viewed as configuration space of a mechanical system. In this paper we
complete the computation of the topological complexity of the configuration
space of n distinct points in Euclidean m-space for all m>1$ and n>1; the
answer was previously known in the cases m=2 and m odd. We also give several
useful general results concerning sharpness of upper bounds for the topological
complexity.


title: Statistical Physics of Hard Optimization Problems

abstract:
  Optimization is fundamental in many areas of science, from computer science
and information theory to engineering and statistical physics, as well as to
biology or social sciences. It typically involves a large number of variables
and a cost function depending on these variables. Optimization problems in the
NP-complete class are particularly difficult, it is believed that the number of
operations required to minimize the cost function is in the most difficult
cases exponential in the system size. However, even in an NP-complete problem
the practically arising instances might, in fact, be easy to solve. The
principal question we address in this thesis is: How to recognize if an
NP-complete constraint satisfaction problem is typically hard and what are the
main reasons for this? We adopt approaches from the statistical physics of
disordered systems, in particular the cavity method developed originally to
describe glassy systems. We describe new properties of the space of solutions
in two of the most studied constraint satisfaction problems - random
satisfiability and random graph coloring. We suggest a relation between the
existence of the so-called frozen variables and the algorithmic hardness of a
problem. Based on these insights, we introduce a new class of problems which we
named "locked" constraint satisfaction, where the statistical description is
easily solvable, but from the algorithmic point of view they are even more
challenging than the canonical satisfiability.


title: Motion planning in spaces with small fundamental group

abstract:
  We establish sharp upper bounds for the topological complexity of motion
planning problem in spaces with small fundamental group, i.e. when it is finite
of small order or has small cohomological dimension.


title: Counterparts to the Nuclear Bulge X-ray source population

abstract:
  We present an initial matching of the source positions of the Chandra Nuclear
Bulge X-ray sources to the new UKIDSS-GPS near-infrared survey of the Nuclear
Bulge. This task is made difficult by the extremely crowded nature of the
region, despite this, we find candidate counterparts to ~50% of the X-ray
sources. We show that detection in the J-band for a candidate counterpart to an
X-ray source preferentially selects those candidate counterparts in the
foreground whereas candidate counterparts with only detections in the H and
K-bands are more likely to be Nuclear Bulge sources. We discuss the planned
follow-up for these candidate counterparts.


title: High-dimensional additive modeling

abstract:
  We propose a new sparsity-smoothness penalty for high-dimensional generalized
additive models. The combination of sparsity and smoothness is crucial for
mathematical theory as well as performance for finite-sample data. We present a
computationally efficient algorithm, with provable numerical convergence
properties, for optimizing the penalized likelihood. Furthermore, we provide
oracle results which yield asymptotic optimality of our estimator for high
dimensional but sparse additive models. Finally, an adaptive version of our
sparsity-smoothness penalized approach yields large additional performance
gains.


title:
Temperature dependence of nonlinear auto-oscillator linewidths:
  Application to spin-torque nano-oscillators

abstract:
  The temperature dependence of the generation linewidth for an auto-oscillator
with a nonlinear frequency shift is calculated. It is shown that the frequency
nonlinearity creates a finite correlation time, tau, for the phase
fluctuations. In the low-temperature limit in which the spectral linewidth is
smaller than 1/tau, the line shape is approximately Lorentzian and the
linewidth is linear in temperature. In the opposite high-temperature limit in
which the linewidth is larger than 1/tau, the nonlinearity leads to an apparent
"inhomogeneous broadening" of the line, which becomes Gaussian in shape and has
a square-root dependence on temperature. The results are illustrated for the
spin-torque nano-oscillator.


title: Gravitational waves from stellar encounters

abstract:
  The emission of gravitational waves from a system of massive objects
interacting on elliptical, hyperbolic and parabolic orbits is studied in the
quadrupole approximation. Analytical expressions are then derived for the
gravitational wave luminosity, the total energy output and gravitational
radiation amplitude. A crude estimate of the expected number of events towards
peculiar targets (i.e. globular clusters) is also given. In particular, the
rate of events per year is obtained for the dense stellar cluster at the
Galactic Center.


title: Inflationary Spectra from Lorentz Violating Dissipative Models

abstract:
  The sensitivity of inflationary spectra to initial conditions is addressed in
the context of a phenomenological model that breaks Lorentz invariance by
dissipative effects above some threshold energy $\Lambda$. These effects are
obtained dynamically by coupling the fluctuation modes to extra degrees of
freedom which are unobservable below $\Lambda$. Because of the strong
dissipative effects in the early propagation, only the state of the extra
degrees of freedom is relevant for the power spectrum. If this state is the
ground state, and if $\Lambda$ is much larger than the Hubble scale $H$, the
standard spectrum is recovered. Using analytical and numerical methods, we
calculate the modifications for a large class of dissipative models. For all of
these, we show that the leading modification (in an expansion in $H/\Lambda$)
is linear in the decay rate evaluated at horizon exit, and that high frequency
superimposed oscillations are not generated. The modification is negative when
the decay rate decreases slower than the cube of $H$, which means that there is
a loss of power on the largest scales.


title: Cosmic Radiative Feedback from Reionization

abstract:
  We explore the effect of cosmic radiative feedback from the sources of
reionization on the thermal evolution of the intergalactic medium. We find that
different prescriptions for this feedback predict quite different thermal and
reionization histories. In spite of this, current data can not discriminate
among different reionization scenarios. We find that future observations both
from 21-cm and CMB experiments can be used to break the degeneracy among model
parameters provided that we will be able to remove the foreground signal at the
percent (or better) level.


title:
Theoretical properties of Cook's PFC dimension reduction algorithm for
  linear regression

abstract:
  We analyse the properties of the Principal Fitted Components (PFC) algorithm
proposed by Cook. We derive theoretical properties of the resulting estimators,
including sufficient conditions under which they are $\sqrt{n}$-consistent, and
explain some of the simulation results given in Cook's paper. We use techniques
from random matrix theory and perturbation theory. We argue that, under Cook's
model at least, the PFC algorithm should outperform the Principal Components
algorithm.


title: Three Dimensional Quantum Geometry and Deformed Poincare Symmetry

abstract:
  We study a three dimensional non-commutative space emerging in the context of
three dimensional Euclidean quantum gravity. Our starting point is the
assumption that the isometry group is deformed to the Drinfeld double D(SU(2)).
We generalize to the deformed case the construction of the flat Euclidean space
as the quotient of its isometry group ISU(2) by SU(2). We show that the algebra
of functions becomes the non-commutative algebra of SU(2) distributions endowed
with the convolution product. This construction gives the action of ISU(2) on
the algebra and allows the determination of plane waves and coordinate
functions. In particular, we show that: (i) plane waves have bounded momenta;
(ii) to a given momentum are associated several SU(2) elements leading to an
effective description of an element in the algebra in terms of several physical
scalar fields; (iii) their product leads to a deformed addition rule of momenta
consistent with the bound on the spectrum. We generalize to the non-commutative
setting the local action for a scalar field. Finally, we obtain, using harmonic
analysis, another useful description of the algebra as the direct sum of the
algebra of matrices. The algebra of matrices inherits the action of ISU(2):
rotations leave the order of the matrices invariant whereas translations change
the order in a way we explicitly determine.


title: Evolution of Massive Protostars with High Accretion Rates

abstract:
  Formation of massive stars by accretion requires a high accretion rate of >
10^-4 M_sun/yr to overcome the radiation pressure barrier of the forming stars.
Here, we study evolution of protostars accreting at such high rates, by solving
the structure of the central star and the inner accreting envelope
simultaneously. The protostellar evolution is followed starting from small
initial cores until their arrival at the stage of the Zero-Age Main Sequence
(ZAMS) stars. An emphasis is put on evolutionary features different from those
with a low accretion rate of 10^-5 M_sun/yr, which is presumed in the standard
scenario for low-mass star formation. With the high accretion rate of 10^-3
M_sun/yr, the protostellar radius becomes very large and exceeds 100 R_sun. It
is not until the stellar mass reaches 40 M_sun that hydrogen burning begins and
the protostar reaches the ZAMS phase, and this ZAMS arrival mass increases with
the accretion rate. At a very high accretion rate of > 3 x 10^-3 M_sun/yr, the
total luminosity of the protostar becomes so high that the resultant radiation
pressure inhibits the growth of the protostars under steady accretion before
reaching the ZAMS stage. Therefore, the evolution under the critical accretion
rate 3 x 10^-3 M_sun/yr gives the upper mass limit of possible
pre-main-sequence stars at 60 M_sun. The upper mass limit of MS stars is also
set by the radiation pressure onto the dusty envelope under the same accretion
rate at 250 M_sun. We also propose that the central source enshrouded in the
Orion KL/BN nebula has effective temperature and luminosity consistent with our
model, and is a possible candidate for such protostars growing under the high
accretion rate. (abridged)


title:
Fresnel and Fraunhofer diffraction of a laser Gaussian beam by
  fork-shaped gratings

abstract:
  Expressions describing the vortex beams, which are generated in a process of
Fresnel diffraction of a Gaussian beam, incident out of waist on a fork-shaped
gratings of arbitrary integer charge p, and vortex spots in the case of
Fraunhofer diffraction by these gratings are deduced. The common general
transmission function of the gratings is defined and specialized for the cases
of amplitude holograms, binary amplitude gratings, and their phase versions.
Optical vortex beams, or carriers of phase singularity with charges mp and -mp,
are the higher negative and positive diffraction order beams. The radial part
of their wave amplitudes is described by the product of mp-th order
Gauss-doughnut function and a Kummer function, or by the first order
Gauss-doughnut function and a difference of two modified Bessel functions,
whose orders do not match the singularity charge value. The wave amplitude and
the intensity distributions are discussed for the near and far field, in the
focal plane of a convergent lens, as well as the specialization of the results
when the grating charge p=0, i.e. the grating turns from forked into
rectilinear. The analytical expressions for the vortex radii are also
discussed.


title: The Nuclear Bulge extinction

abstract:
  We present a new, high resolution (5" per pixel) near-infrared extinction map
of the Nuclear Bulge using data from the UKIDSS-GPS. Using photometry from the
J, H and K-bands we show that the extinction law parameter is also highly
variable in this region on similar scales to the absolute extinction. We show
that only when this extinction law variation is taken into account can the
extinction be measured consistently at different wavelengths.


title: Ruin models with investment income

abstract:
  This survey treats the problem of ruin in a risk model when assets earn
investment income. In addition to a general presentation of the problem, topics
covered are a presentation of the relevant integro-differential equations,
exact and numerical solutions, asymptotic results, bounds on the ruin
probability and also the possibility of minimizing the ruin probability by
investment and possibly reinsurance control. The main emphasis is on continuous
time models, but discrete time models are also covered. A fairly extensive list
of references is provided, particularly of papers published after 1998. For
more references to papers published before that, the reader can consult [47].


title: About Geometric Scaling and Small-x Evolution at RHIC and LHC

abstract:
  We show that the whole range of RHIC data for hadron production in d-Au
collisions is compatible with geometric scaling. To establish the scaling
violations expected from small-x evolution a larger kinematic range in
transverse momentum and rapidity would be needed. We point out that the
fall-off of the p_t distribution of produced hadrons at large p_t is a
sensitive probe of small-x evolution especially at the LHC.


title: The implicit equation of a canal surface

abstract:
  A canal surface is an envelope of a one parameter family of spheres. In this
paper we present an efficient algorithm for computing the implicit equation of
a canal surface generated by a rational family of spheres. By using Laguerre
and Lie geometries, we relate the equation of the canal surface to the equation
of a dual variety of a certain curve in 5-dimensional projective space. We
define the \mu-basis for arbitrary dimension and give a simple algorithm for
its computation. This is then applied to the dual variety, which allows us to
deduce the implicit equations of the the dual variety, the canal surface and
any offset to the canal surface.


title: A Neutron diffraction study of multiferroics RMn2O5

abstract:
  The magnetic properties of RMn2O5 multiferrroics as obtained by unpolarized
and polarized neutron diffraction experiments are reviewed. We discuss the
qualitative features of the magnetic phase diagram both in zero magnetic field
and in field and analyze the commensurate magnetic structure and its coupling
to an applied electric field. The origin of ferrolectricity is discussed based
on calculations of the ferroelectric polarization predicted by different
microscopic coupling mechanisms (exchange striction and cycloidal spin-orbit
models). A minimal model containing a small set of parameters is also presented
in order to understand the propagation of the magnetic structure along the
c-direction.


title:
Gauge Fixing in the Maxwell Like Gravitational Theory in Minkowski
  Spacetime and in the Equivalent Lorentzian Spacetime

abstract:
  In a previous paper we investigate a Lagrangian field theory for the
gravitational field (which is there represented by a section g^a of the
orthonormal coframe bundle over Minkowski spacetime. Such theory, under
appropriate conditions, has been proved to be equivalent to a Lorentzian
spacetime structure, where the metric tensor satisfies Einstein field
equations. Here, we first recall that according to quantum field theory ideas
gravitation is described by a Lagrangian theory of a possible massive graviton
field (generated by matter fields and coupling also to itself) living in
Minkowski spacetime. The graviton field is moreover supposed to be represented
by a symmetric tensor field h carrying the representations of spin two and zero
of the Lorentz group. Such a field, then (as it is well known), must
necessarily satisfy the gauge condition given by Eq.(3) below. Next, we
introduce an ansatz relating h to the 1-form fields g^a. Then, using the
Clifford bundle formalism we derive, from our Lagrangian theory, the exact wave
equation for the graviton and investigate the role of the gauge condition given
by Eq.(3) in obtaining a reliable conservation law for the energy-momentum
tensor of the gravitational plus the matter fields in Minkowski spacetime.
Finally we ask the question: does Eq.(3) fix any gauge condition for the field
g of the effective Lorentzian spacetime structure that represents the field h
in our theory? We show that no gauge condition is fixed a priory, as is the
case in General Relativity. Moreover we investigate under which conditions we
may fix Logunov gauge condition.


title: Complexity of Hybrid Logics over Transitive Frames

abstract:
  This paper examines the complexity of hybrid logics over transitive frames,
transitive trees, and linear frames. We show that satisfiability over
transitive frames for the hybrid language extended with the downarrow operator
is NEXPTIME-complete. This is in contrast to undecidability of satisfiability
over arbitrary frames for this language (Areces, Blackburn, Marx 1999). It is
also shown that adding the @ operator or the past modality leads to
undecidability over transitive frames. This is again in contrast to the case of
transitive trees and linear frames, where we show these languages to be
nonelementarily decidable. Moreover, we establish 2EXPTIME and EXPTIME upper
bounds for satisfiability over transitive frames and transitive trees,
respectively, for the hybrid Until/Since language. An EXPTIME lower bound is
shown to hold for the modal Until language over both frame classes.


title: Front instabilities in evaporatively dewetting nanofluids

abstract:
  Various experimental settings that involve drying solutions or suspensions of
nanoparticles -- often called nanofluids -- have recently been used to produce
structured nanoparticle layers. In addition to the formation of polygonal
networks and spinodal-like patterns, the occurrence of branched structures has
been reported. After reviewing the experimental results we use a modified
version of the Monte Carlo model first introduced by Rabani et al. [Nature 426,
271 (2003)] to study structure formation in evaporating films of nanoparticle
solutions for the case that all structuring is driven by the interplay of
evaporating solvent and diffusing nanoparticles.
  After introducing the model and its general behavior we focus on receding
dewetting fronts which are initially straight but develop a transverse
fingering instability. We analyze the dependence of the characteristics of the
resulting branching patterns on the driving chemical potential, the mobility
and concentration of the nanoparticles, and the interaction strength between
liquid and nanoparticles. This allows us to understand the underlying
instability mechanism.


title:
XMM-Newton observations of the Small Magellanic Cloud: Be/X-ray binary
  pulsars active between October 2006 and June 2007

abstract:
  (abridged) We analysed eight XMM-Newton observations toward the Small
Magellanic Cloud (SMC), performed between October 2006 and June 2007, to
investigate high mass X-ray binary systems. We found new X-ray binary pulsars
with periods of 202 s (XMMU J005929.0-723703), 342 s (XMMU J005403.8-722632),
645 s (XMMU J005535.2-722906) and 325 s (XMMU J005252.1-721715), in the latter
case confirming the independent discovery in Chandra data. In addition we
detected sixteen known Be/X-ray binary pulsars and six ROSAT-classified
candidate high mass X-ray binaries. From one of the candidates, RX
J0058.2-7231, we discovered X-ray pulsations with a period of 291 s which makes
it the likely counterpart of XTE J0051-727. From the known pulsars, we revise
the pulse period of CXOU J010206.6-714115 to 967 s, and we detected the 18.37 s
pulsar XTE J0055-727 (= XMM J004911.4-724939) in outburst, which allowed us to
localise the source. The pulse profiles of the X-ray pulsars show a large
variety of shapes from smooth to highly structured patterns and differing
energy dependence. For all the candidate high mass X-ray binaries optical
counterparts can be identified with magnitudes and colours consistent with Be
stars. Twenty of the Be/X-ray binaries were detected with X-ray luminosities in
the range 1.5x10^35 erg/s - 5.5x10^36 erg/s. The majority of the spectra is
well represented by an absorbed power-law with an average power-law index of
0.93. The absorption (in addition to the Galactic foreground value) varies over
a wide range between a few 10^20 H cm^-2 and several 10^22 H cm^-2. An overall
correlation of the absorption with the total SMC HI column density suggests
that the absorption seen in the X-ray spectra is often largely caused by
interstellar gas.


title: Irrevocable Multi-Armed Bandit Policies

abstract:
  This paper considers the multi-armed bandit problem with multiple
simultaneous arm pulls. We develop a new `irrevocable' heuristic for this
problem. In particular, we do not allow recourse to arms that were pulled at
some point in the past but then discarded. This irrevocable property is highly
desirable from a practical perspective. As a consequence of this property, our
heuristic entails a minimum amount of `exploration'. At the same time, we find
that the price of irrevocability is limited for a broad useful class of bandits
we characterize precisely. This class includes one of the most common
applications of the bandit model, namely, bandits whose arms are `coins' of
unknown biases. Computational experiments with a generative family of large
scale problems within this class indicate losses of up to 5 to 10% relative to
an upper bound on the performance of an optimal policy with no restrictions on
exploration. We also provide a worst-case theoretical analysis that shows that
for this class of bandit problems, the price of irrevocability is uniformly
bounded: our heuristic earns expected rewards that are always within a factor
of 1/8 of an optimal policy with no restrictions on exploration. In addition to
being an indicator of robustness across all parameter regimes, this analysis
sheds light on the structural properties that afford a low price of
irrevocability.


title:
Spin dynamics in the pseudogap state of a high-temperature
  superconductor

abstract:
  The pseudogap is one of the most pervasive phenomena of high temperature
superconductors. It is attributed either to incoherent Cooper pairing setting
in above the superconducting transition temperature Tc, or to a hidden order
parameter competing with superconductivity. Here we use inelastic neutron
scattering from underdoped YBa(2)Cu(3)O(6.6) to show that the dispersion
relations of spin excitations in the superconducting and pseudogap states are
qualitatively different. Specifically, the extensively studied "hour glass"
shape of the magnetic dispersions in the superconducting state is no longer
discernible in the pseudogap state and we observe an unusual "vertical"
dispersion with pronounced in-plane anisotropy. The differences between
superconducting and pseudogap states are thus more profound than generally
believed, suggesting a competition between these two states. Whereas the
high-energy excitations are common to both states and obey the symmetry of the
copper oxide square lattice, the low-energy excitations in the pseudogap state
may be indicative of collective fluctuations towards a state with broken
orientational symmetry predicted in theoretical work.


title: On some block ciphers and imprimitive groups

abstract:
  The group generated by the round functions of a block ciphers is a widely
investigated problem. We identify a large class of block ciphers for which such
group is easily guaranteed to be primitive. Our class includes the AES and the
SERPENT.


title:
Observations of Isolated Neutron Stars with the ESO Multi-Conjugate
  Adaptive Optics Demonstrator

abstract:
  High-energy observations have unveiled peculiar classes of isolated neutron
stars which, at variance with radio pulsars, are mostly radio silent and not
powered by the star rotation. Among these objects are the magnetars,
hyper-magnetized neutron stars characterized by transient X-ray/gamma-ray
emission, and neutron stars with purely thermal, and in most cases stationary,
X-ray emission (a.k.a., X-ray dim isolated neutron stars or XDINSs). While
apparently dissimilar in their high-energy behavior and age, both magnetars and
XDINSs have similar periods and unusually high magnetic fields. This suggests a
tantalizing scenario where the former evolve into the latter.Discovering so far
uninvestigated similarities between the multi-wavelength properties of these
two classes would be a further step forward to establish an evolutionary
scenario. A most promising channels is the near infrared (NIR) one, where
magnetars are characterized by a distinctive spectral flattening with respect
to the extrapolation of the soft X-ray spectrum.We observed the two XDINSs RX
J0420.0-5022 and RX J1856.5-3754 with the Multi-Conjugate Adaptive Optics
Demonstrator (MAD) at the Very Large Telescope (VLT) as part of the instrument
guaranteed time observations program, to search for their NIR counterparts.
Both RX J1856.5-3754 and RX J0420.0-5022 were not detected down to K_s ~20 and
Ks ~21.5, respectively. In order to constrain the relation between XDINSs and
magnetars it would be of importance to perform deeper NIR observations. A good
candidate is 1RXS J214303.7+065419 which is the XDINS with the highest inferred
magnetic field.


title:
Ultrafast control of donor-bound electron spins with single detuned
  optical pulses

abstract:
  The ability to control spins in semiconductors is important in a variety of
fields including spintronics and quantum information processing. Due to the
potentially fast dephasing times of spins in the solid state [1-3], spin
control operating on the picosecond or faster timescale may be necessary. Such
speeds, which are not possible to attain with standard electron spin resonance
(ESR) techniques based on microwave sources, can be attained with broadband
optical pulses. One promising ultrafast technique utilizes single broadband
pulses detuned from resonance in a three-level Lambda system [4]. This
attractive technique is robust against optical pulse imperfections and does not
require a fixed optical reference phase. Here we demonstrate the principle of
coherent manipulation of spins theoretically and experimentally. Using this
technique, donor-bound electron spin rotations with single-pulse areas
exceeding pi/4 and two-pulses areas exceeding pi/2 are demonstrated. We believe
the maximum pulse areas attained do not reflect a fundamental limit of the
technique and larger pulse areas could be achieved in other material systems.
This technique has applications from basic solid-state ESR spectroscopy to
arbitrary single-qubit rotations [4, 5] and bang-bang control[6] for quantum
computation.


title: Investigations of thermometric characteristics of p+-n - type GaP diodes

abstract:
  The technique of obtaining of p+-n-type gallium phosphide diode epitaxial
structures from liquid phase was developed as well as pilot samples of diode
temperature sensors were fabricated based on them. Thermometric and
current-voltage characteristics of the test diodes were measured in the
temperature range of 80 / 520K and their basic technical characteristics were
determined. An availability of application of the structures developed as
sensing elements of high-temperature heat sensors was shown.


title:
On the Allen-Cahn equation in the Grushin plane: a monotone entire
  solution that is not one-dimensional

abstract:
  We consider solutions of the Allen-Cahn equation in the whole Grushin plane
and we show that if they are monotone in the vertical direction, then they are
stable and they satisfy a good energy estimate. However, they are not
necessarily one-dimensional, as a counter-example shows.


title: Optimal oracle inequalities for model selection

abstract:
  Model selection is often performed by empirical risk minimization. The
quality of selection in a given situation can be assessed by risk bounds, which
require assumptions both on the margin and the tails of the losses used.
Starting with examples from the 3 basic estimation problems, regression,
classification and density estimation, we formulate risk bounds for empirical
risk minimization under successively weakening conditions and prove them at a
very general level, for general margin and power tail behavior of the excess
losses.


title:
An Interaction Potential for Atomic Simulations of Conventional High
  Explosives

abstract:
  In an effort to develop a chemically reactive interaction potential suitable
for application to the study of conventional, organic explosives, we have
modified the diatomic AB potential of Brenner et al. such that it exhibits
improved detonation characteristics. In particular, equilibrium molecular
dynamics (MD) calculations of the modified potential demonstrate that the
detonation products have an essentially diatomic, rather than polymeric,
composition and that the detonation Hugoniot has the classic, concave-upward
form. Nonequilibrium MD calculations reveal the separation of scales between
chemical and hydrodynamic effects essential to the Zeldovitch, von Neumann, and
Doering theory.


title:
The Spin-Orbit Alignment of the HD17156 Transiting Eccentric Planetary
  System

abstract:
  We present high precision radial velocity observations of HD17156 during a
transit of its eccentric Jovian planet. In these data, we detect the
Rossiter-McLaughlin effect, which is an apparent perturbation in the velocity
of the star due to the progressive occultation of part of the rotating stellar
photosphere by the transiting planet. This system had previously been reported
by Narita et al. (2008) to exhibit a lambda = 62 +/- 25 degree misalignment of
the projected planetary orbital axis and the stellar rotation axis. We model
our data, along with the Narita et al. data, and obtain lambda = 9.4 +/- 9.3
degrees for the combined data set. We thus conclude that the planetary orbital
axis is actually very well aligned with the stellar rotation axis.


title: Noncommutative Cartan sub-algebras of C*-algebras

abstract:
  J. Renault has recently found a generalization of the caracterization of
C*-diagonals obtained by A. Kumjian in the eighties, which in turn is a
C*-algebraic version of J. Feldman and C. Moore's well known Theorem on Cartan
subalgebras of von Neumann algebras. Here we propose to give a version of
Renault's result in which the Cartan subalgebra is not necessarily commutative
[sic]. Instead of describing a Cartan pair as a twisted groupoid C*-algebra we
use N. Sieben's notion of Fell bundles over inverse semigroups which we believe
should be thought of as "twisted etale groupoids with noncommutative unit
space". En passant we prove a theorem on uniqueness of conditional
expectations.


title: Simple Glass Models and their Quantum Annealing

abstract:
  We study first order quantum phase transitions in mean-field spin glasses. We
solve the quantum Random Energy Model using elementary methods and show that at
the transition the eigenstate suddenly projects onto the unperturbed ground
state and that the gap between the lowest states is exponentially small in the
system size. We argue that this is a generic feature of all `Random First
Order' models, which includes benchmarks such as random satisfiability. We
introduce a two-time instanton to calculate this gap in general, and discuss
the consequences for quantum annealing.


title: Resonances and Unitarity in Weak Boson Scattering at the LHC

abstract:
  A crucial test of the Standard Model is the measurement of electroweak
gauge-boson scattering. In this paper, we describe a generic parameterization
aimed at a realistic simulation of weak-boson scattering at the LHC. The
parameterization implements resonances of all possible spin and isospin
combinations, properly matched to the low-energy effective (chiral) Lagrangian,
includes leading higher-order effects and contains a minimal unitarization
scheme. We implement the parameterization in the Monte-Carlo event generator
WHIZARD and present results for complete partonic cross-section integration and
event generation. We provide a comparison with the effective W approximation
that previously has been used for most WW scattering studies at hadron
colliders.


title:
Solution of Master Equations for the anharmonic oscillator interacting
  with a heat bath and for parametric down conversion process

abstract:
  We solve analytically master equations that describe a cavity filled with a
kerr medium, taking into account the dissipation induced by the environment,
and parametric down conversion processes. We use superoperator techniques.


title: Molecular Dynamics Simulations of Detonation Instability

abstract:
  After making modifications to the Reactive Empirical Bond Order potential for
Molecular Dynamics (MD) of Brenner et al. in order to make the model behave in
a more conventional manner, we discover that the new model exhibits detonation
instability, a first for MD. The instability is analyzed in terms of the
accepted theory.


title: Smooth self-similar blow-up profiles for the wave map equation

abstract:
  Consider the equivariant wave map equation from Minkowski space to a
rotationnally symmetric manifold which has an equator (example: the sphere). In
dimension 3, this article gives a necessary and sufficient condition for the
existence of a smooth self-similar blow up profile. More generally, we study
the relation between 1. the minimizing properties of the equator map for the
(elliptic) Dirichlet energy and 2. the existence of a smooth blow-up profile
for the (hyperbolic) wave map problem. Several applications of this approach
are described.


title:
Discovery of kilohertz quasi-periodic oscillations and state transitions
  in the low-mass X-ray binary 1E~1724-3045 (Terzan 2)

abstract:
  We have studied the rapid X-ray time variability in 99 pointed observations
with the Rossi X-ray Timing Explorer (RXTE)'s Proportional Counter Array of the
low-mass X-ray binary 1E~1724--3045 which includes, for the first time,
observations of this source in its island and banana states, confirming the
atoll nature of this source. We report the discovery of kilohertz
quasi-periodic oscillations (kHz QPOs). Although we have 5 detections of the
lower kHz QPO and one detection of the upper kHz QPO, in none of the
observations we detect both QPOs simultaneously. By comparing the dependence of
the rms amplitude with energy of kHz QPOs in different atoll sources, we
conclude that this information cannot be use to unambiguously identify the
kilohertz QPOs as was previously thought. We find that Terzan~2 in its
different states shows timing behavior similar to that seen in other
neutron-star low mass X-ray binaries (LMXBs). We studied the flux transitions
observed between February 2004 and October 2005 and conclude that they are due
to changes in the accretion rate.


title:
A Numerical Model of Hercules A by Magnetic Tower: Jet/Lobe Transition,
  Wiggling, and the Magnetic Field Distribution

abstract:
  We apply magnetohydrodynamic (MHD) modeling to the radio galaxy Hercules A
for investigating the jet-driven shock, jet/lobe transition, wiggling, and
magnetic field distribution associated with this source. The model consists of
magnetic tower jets in a galaxy cluster environment, which has been discussed
in a series of our papers. The profile of underlying ambient gas plays an
important role in jet-lobe morphology. The balance between the magnetic
pressure generated by axial current and the ambient gas pressure can determine
the lobe radius. The jet body is confined jointly by the external pressure and
gravity inside the cluster core radius R_c, while outside R_c it expands
radially to form fat lobes in a steeply decreasing ambient thermal pressure
gradient. The current-carrying jets are responsible for generating a strong,
tightly wound helical magnetic field. This magnetic configuration will be
unstable against the current-driven kink mode and it visibly grows beyond R_c
where a separation between the jet forward and return currents occurs. The
reversed pinch profile of global magnetic field associated with the jet and
lobes produces projected B-vector distributions aligned with the jet flow and
the lobe edge. AGN-driven shock powered by the expanding magnetic tower jet
surrounds the jet/lobe structure and heats the ambient ICM. The lobes expand
subsonically; no obvious hot spots are produced at the heads of lobes. Several
key features in our MHD modeling may be qualitatively supported by the
observations of Hercules A.


title:
Geometrically Constructed Bases for Homology of Non-Crossing Partition
  Lattices

abstract:
  For any finite, real reflection group $W$, we construct a geometric basis for
the homology of the corresponding non-crossing partition lattice. We relate
this to the basis for the homology of the corresponding intersection lattice
introduced by Bj\"{o}rner and Wachs in \cite{BW} using a general construction
of a generic affine hyperplane for the central hyperplane arrangement defined
by $W$.


title: Dimension of automorphisms with fixed degree for polynomial algebras

abstract:
  Let $K[x,y]$ be the polynomial algebra in two variables over an algebraically
closed field $K$. We generalize to the case of any characteristic the result of
Furter that over a field of characteristic zero the set of automorphisms
$(f,g)$ of $K[x,y]$ such that $\max\{\text{deg}(f),\text{deg}(g)\}=n\geq 2$ is
constructible with dimension $n+6$. The same result holds for the automorphisms
of the free associative algebra $K< x,y>$. We have also obtained analogues for
free algebras with two generators in Nielsen -- Schreier varieties of algebras.


title: Finite energy scattering for the Lorentz-Maxwell equation

abstract:
  In the case where the charge of the particle is small compared to its mass,
we describe the asymptotics of the Lorentz-Maxwell equation for any
finite-energy data. As time goes to infinity, we prove that the speed of the
particle converges to a certain limit, whereas the electromagnetic field can be
decomposed into a soliton plus a free solution of the Maxwell equation. It is
the first instance of a scattering result for general finite energy data in a
field-particle equation.


title: Cancer Cell Motility: Optimizing Spatial Search Strategies

abstract:
  Aberrantly regulated cell motility is a hallmark of cancer cells. A hybrid
agent-based model has been developed to investigate the synergistic and
antagonistic cell motility-impacting effects of three microenvironment
variables simultaneously: chemoattraction, haptotactic permission, and
biomechanical constraint or resistance. Reflecting distinct cell-specific
intracellular machinery, the cancer cells are modelled as processing a variety
of spatial search strategies that respond to these three influencing factors
with differential weights attached to each. While responding exclusively to
chemoattraction optimizes cell displacement effectiveness, incorporating
permission and resistance components becomes increasingly important with
greater distance to the chemoattractant source and/or after reducing the
ligand's effective diffusion coefficient. Extending this to a heterogeneous
population of cells shows that displacement effectiveness increases with clonal
diversity as characterized by the Shannon index. However, the resulting data
can be fit best to an exponential function, suggesting that there is a level of
population heterogeneity beyond which its added value to the cancer system
becomes minimal as directionality ceases to increase. Possible experimental
extensions and potential clinical implications are discussed.


title: First integrals of linear differential systems

abstract:
  We investigate the problem of the existence of first integrals for
multidimensional and ordinary linear differential systems with constant
coefficients. The spectral method of the first integrals basis construction for
these systems of linear differential equations is developed.


title: Non-simple purely infinite rings

abstract:
  In this paper we introduce the concept of purely infinite rings, which in the
simple case agrees with the already existing notion of pure infiniteness. We
establish various permanence properties of this notion, with respect to passage
to matrix rings, corners, and behaviour under extensions, so being purely
infinite is preserved under Morita equivalence. We show that a wealth of
examples falls into this class, including important analogues of constructions
commonly found in operator algebras. In particular, for any (s-)unital
$K$-algebra having enough nonzero idempotents (for example, for a von Neumann
regular algebra) its tensor product over $K$ with many nonsimple Leavitt path
algebras is purely infinite.


title: On Brownian motion in ideal gas and related principles

abstract:
  Brownian motion of particle interacting with atoms of ideal gas is discussed
as a key problem of kinetics lying at the border between ``dead'' systems like
the Lorentz gas or formal constructs of conceptual Boltzmannian kinetics and
actual ``alive'' systems like mere gas possessing scaleless (1/f) fluctuations
in their kinetic characteristics (e.g. in diffusuvity and mobility of the
``Brownian particle'').


title: Dimer lambda_d Expansion, A Contour Integral Stationary Point Argument

abstract:
  In the development of a presumed asymptotic expansion for lambda_d in
previous work, a basic step involved extracting the asymptotic behavior of a
sum as being dominated by the largest term in the sum. But this argument only
is valid when the terms in the sum are positive. In the case terms in the sum
are not all positive (some of the J_n are negative) we replace the `largest
term' argument by the route of this paper. The sum is replaced by a contour
integral. We then find a stationary point of the integrand that we conjecture
dominates the asymptotic behavior of the integral.


title: Modelling the flyby anomalies using a modification of inertia

abstract:
  The flyby anomalies are unexplained velocity jumps of 3.9, -4.6, 13.5, -2,
1.8 and 0.02 mm/s observed near closest approach during the Earth flybys of six
spacecraft. These flybys are modelled here using a theory that assumes that
inertia is due to a form of Unruh radiation, and varies with acceleration due
to a Hubble-scale Casimir effect. Considering the acceleration of the craft
relative to every particle of the rotating Earth, the theory predicts that
there is a slight reduction in inertial mass with increasing latitude for an
unbound craft, since near the pole it sees a lower average relative
acceleration. Applying this theory to the in- and out-bound flyby paths, with
conservation of momentum, the predicted anomalies were 2.9, -0.9, 20.1, 0.9,
3.2 and -1.3 mm/s. Three of the flyby anomalies were reproduced within error
bars, and the theory explains their recently-observed dependence on the
latitude difference between their incident and exit trajectories. The errors
for the other three flybys were between 1 and 3 mm/s.


title: Orbifolds as stacks?

abstract:
  The first goal of this survey paper is to argue that if orbifolds are
groupoids, then the collection of orbifolds and their maps has to be thought of
as a 2-category. Compare this with the classical definition of Satake and
Thurston of orbifolds as a 1-category of sets with extra structure and/or with
the "modern" definition of orbifolds as proper etale Lie groupoids up to Morita
equivalence.
  The second goal is to describe two complementary ways of thinking of
orbifolds as a 2-category:
  1. the weak 2-category of foliation Lie groupoids, bibundles and equivariant
maps between bibundles and
  2. the strict 2-category of Deligne-Mumford stacks over the category of
smooth manifolds.


title: Two Potential Mechanisms of Spatial Attention in Early Visual Areas

abstract:
  We investigate theoretically the effect of spatial attention on the
contrast-response function (CRF) and orientation-tuning curves in early visual
areas.We look at a model of a hypercolumn developed recently (Persi et al.,
2008), that accounts for both the contrast response and tuning properties in
the primary visual cortex, and extend it to two visual areas.
  The effect of spatial attention is studied in a model of two inter-connected
visual areas, under two hypothesis that do not necessarily contradict. The
first hypothesis is that attention alters inter-areal feedback synaptic
strength, as has been proposed by many previous studies. A second new
hypothesis is that attention effectively alters single neuron input-output
properties. We show that with both mechanisms it is possible to achieve
attentional effects similarly to those observed in experiments, namely
contrast-gain and response-gain effects, while keeping the orientation-tuning
curves width approximately contrast-invariant and attention-invariant.
Nevertheless, some differences occur and are discussed. We propose a simple
test on existing data based on the second hypothesis.


title:
Investigations of a coherently driven semiconductor optical cavity QED
  system

abstract:
  Chip-based cavity quantum electrodynamics (QED) devices consisting of a
self-assembled InAs quantum dot (QD) coupled to a high quality factor GaAs
microdisk cavity are coherently probed through their optical channel using a
fiber taper waveguide. We highlight one particularly important aspect of this
all-fiber measurement setup, which is the accuracy to which the optical
coupling level and optical losses are known relative to typical free-space
excitation techniques. This allows for precise knowledge of the intracavity
photon number and measurement of absolute transmitted and reflected signals.
Resonant optical spectroscopy of the system under both weak and strong driving
conditions are presented, which when compared with a quantum master equation
model of the system allows for determination of the coherent coupling rate
between QD exciton and optical cavity mode, the different levels of elastic and
inelastic dephasing of the exciton state, and the position and orientation of
the QD within the cavity. Pump-probe measurements are also performed in which a
far off-resonant red-detuned control laser beam is introduced into the cavity.
Rather than producing a measurable ac-Stark shift in the exciton line of the
QD, we find that this control beam induces a saturation of the resonant system
response. The broad photoluminescence spectrum resulting from the presence of
the control beam in the cavity points to sub-bandgap absorption in the
semiconductor, and the resulting free-carrier generation, as the likely source
of system saturation.


title: Submillimeter Observations of the Young Low-Mass Object IRAS 04158+2805

abstract:
  We present high spatial resolution Submillimeter Array observations and
supplementary single-dish photometry of the molecular gas and dust around IRAS
04158+2805, a young source with spectral type M5-M6 in the Taurus star-forming
region. A bright, highly elongated dust structure that extends 8" (~1120 AU) in
diameter is revealed in a 883 micron thermal continuum image. This emission
geometry is in good agreement with optical observations that show a similar
structure in absorption, aligned perpendicular to bipolar scattered light
nebulae. However, the interferometric data also clearly demonstrate that the
submillimeter continuum emission is not centrally concentrated, but rather
appears to have a toroidal geometry with substantially lower intensities inside
a radius of ~250-300 AU. Spatially resolved emission from the CO J=3-2
transition exhibits a velocity gradient along the major axis of the dust
structure. If this kinematic pattern is interpreted as the signature of
rotation around a central object, a relatively low mass is inferred (M_star =
0.3 M_sun, with a ~50% uncertainty). We discuss several possible explanations
for the observed gas and dust environment around IRAS 04158+2805, including a
flattened envelope with an outflow cavity and a large circumbinary ring. This
source offers unique views of the gas and dust environment surrounding a young
low-mass stellar system. Its properties are generally not commensurate with
formation scenarios for such low-mass objects that rely on dynamical ejection,
but rather confirms that a single mechanism - molecular cloud core collapse and
fragmentation - can produce stars over a wide range of stellar masses (at least
an order of magnitude).


title: Synergetics and Its Application to Literature and Architecture

abstract:
  A series of phenomena pertaining to economics, quantum physics, language,
literary criticism, and especially architecture is studied from the standpoint
of synergetics (the study of self-organizing complex systems). It turns out
that a whole series of concrete formulas describing these phenomena is
identical in these different situations. This is the case of formulas relating
to the Bose-Einstein distribution of particles and the distribution of words
from a frequency dictionary. This also allows to apply a "quantized" from of
the Zipf law to the problem of the authorship of 'Quiet Flows the Don' and to
the"blending in" of new architectural structures in an existing environment.


title: Detecting and Quantifying Entanglement via Bayesian Updating

abstract:
  We show how a straightforward Bayesian updating procedure allows one to
detect and quantify entanglement from any finite set of measurement results.
The measurements do not have to be tomographically complete, and may consist of
POVMs rather than von Neumann measurements. One obtains a probability that
one's state is entangled and an estimate of any desired entanglement measure,
including their error bars. As an example we consider (tomographically
incomplete) spin correlation measurements on both 2-qubit and 3-qubit states.
As byproducts we obtain estimates of the volume of entangled states vs. states
that violate a given Bell inequality for both pure and mixed states, and an
inequality that relates the expectation value of the Bell operator to the
negativity.


title:
Beam-Energy and System-Size Dependence of Dynamical Net Charge
  Fluctuations

abstract:
  We present measurements of net charge fluctuations in $Au + Au$ collisions at
$\sqrt{s_{NN}} = $ 19.6, 62.4, 130, and 200 GeV, $Cu + Cu$ collisions at
$\sqrt{s_{NN}} = $ 62.4, 200 GeV, and $p + p$ collisions at $\sqrt{s} = $ 200
GeV using the net charge dynamical fluctuations measure $\nu_{+-,dyn}$. The
dynamical fluctuations are non-zero at all energies and exhibit a rather modest
dependence on beam energy. We find that at a given energy and collision system,
net charge dynamical fluctuations violate $1/N_{ch}$ scaling, but display
approximate $1/N_{part}$ scaling. We observe strong dependence of dynamical
fluctuations on the azimuthal angular range and pseudorapidity widths.


title: Useful transformations: from ion-laser interactions to master equations

abstract:
  We show set of transformations which allow to obtain analytic solutions in
several quantum-optical problems. We start with the ion-laser (time dependent)
interaction, continue with the problem of a slow atom interacting with a
quantized field to end with a master equation that describes losses. In all
cases it is shown that one may find useful transformations that simplify the
problems.


title: Established Clustering Procedures for Network Analysis

abstract:
  In light of the burgeoning interest in network analysis in the new millenium,
we bring to the attention of contemporary network theorists, a two-stage
double-standarization and hierarchical clustering (single-linkage-like)
procedure devised in 1974. In its many applications over the next
decade--primarily to the migration flows between geographic subdivisions within
nations--the presence was often revealed of ``hubs''. These are, typically,
``cosmopolitan/non-provincial'' areas--such as the French capital, Paris--which
send and receive people relatively broadly across their respective nations.
Additionally, this two-stage procedure--which ``might very well be the most
successful application of cluster analysis'' (R. C. Dubes)--has detected many
(physically or socially) isolated groups (regions) of areas, such as those
forming the southern islands, Shikoku and Kyushu, of Japan, the Italian islands
of Sardinia and Sicily, and the New England region of the United States.
Further, we discuss a (complementary) approach developed in 1976, involving the
application of the max-flow/min-cut theorem to raw/non-standardized flows.

categories: physics.soc-ph cs.SI physics.data-an stat.AP


title: Dissecting the hydrogen bond: a Quantum Monte Carlo approach

abstract:
  We present a variational MonteCarlo (VMC) and lattice regularized diffusion
MonteCarlo (LRDMC) study of the binding energy and dispersion curve of the
water dimer. As a variation ansatz we use the JAGP wave function, an
implementation of the resonating valence bond (RVB) idea. Actually one the aim
of the present work is to investigate how the bonding of two water molecules,
as a prototype of the hydrogen-bonded complexes, could be described within an
JAGP approach. Using a pseudopotential for the inert core of the Oxygen, with a
full optimization of the variational parameters, we obtain at the VMC level a
binding energy of -4.5(0.1) Kcal/mol, while LRDMC calculations gives -4.9(0.1)
Kcal/mol (experiment 5 Kcal/Mol). The calculated dispersion curve reproduces
both at the VMC and LRDMC level the miminum position and the curvature.The
quality of the WF gives us the possibility to dissect the binding energy in
different contributions by appropriately switching off determinantal and
Jastrow terms in the JAGP: we estimate the dynamical contribution to the
binding energy to be of the order of 1.4(0.2) Kcal/Mol whereas the covalent
contribution about 1.0(0.2) Kcal/Mol. JAGP reveales thus a promising WF for
describing systems where both dispersive and covalent forces play an important
role.


title:
Hamiltonian approach for the wave packet dynamics: Beyond Gaussian wave
  functions

abstract:
  It is well known that the Gaussian wave packet dynamics can be written in
terms of Hamilton equations in the extended phase space that is twice as large
as in the corresponding classical system. We construct several generalizations
of this approach that include non-Gausssian wave packets. These generalizations
lead to the further extension of the phase space while retaining the Hamilton
structure of the equations of motion. We compare the Gaussian dynamics with
these non-Gaussian extensions for a particle with the quartic potential.


title:
Quantum analysis of a nonlinear microwave cavity-embedded dc SQUID
  displacement detector

abstract:
  We carry out a quantum analysis of a dc SQUID mechanical displacement
detector, comprising a SQUID with mechanically compliant loop segment, which is
embedded in a microwave transmission line resonator. The SQUID is approximated
as a nonlinear, current dependent inductance, inducing an external flux
tunable, nonlinear Duffing self-interaction term in the microwave resonator
mode equation. Motion of the compliant SQUID loop segment is transduced
inductively through changes in the external flux threading SQUID loop, giving a
ponderomotive, radiation pressure type coupling between the microwave and
mechanical resonator modes. Expressions are derived for the detector signal
response and noise, and it is found that a soft-spring Duffing self-interaction
enables a closer approach to the displacement detection standard quantum limit,
as well as cooling closer to the ground state.


title: Prediction of a Photon Peak in Heavy Ion Collisions

abstract:
  We show that if a flavour-less vector meson remains bound after
deconfinement, and if its limiting velocity in the quark-gluon plasma is
subluminal, then this meson produces a distinct peak in the spectrum of thermal
photons emitted by the plasma. We also demonstrate that this effect is a
universal property of all strongly coupled, large-Nc plasmas with a gravity
dual. For the J/psi the corresponding peak lies between 3 and 5 GeV and could
be observed at LHC.


title:
Cluster-based density-functional approach to quantum transport through
  molecular and atomic contacts

abstract:
  We present a cluster-based density-functional approach to model charge
transport through molecular and atomic contacts. The electronic structure of
the contacts is determined in the framework of density functional theory, and
the parameters needed to describe transport are extracted from finite clusters.
A similar procedure, restricted to nearest-neighbor interactions in the
electrodes, has been presented by Damle et al. [Chem. Phys. 281, 171 (2002)].
Here, we show how to systematically improve the description of the electrodes
by extracting bulk parameters from sufficiently large metal clusters. In this
way we avoid problems arising from the use of nonorthogonal basis functions.
For demonstration we apply our method to electron transport through Au contacts
with various atomic-chain configurations and to a single-atom contact of Al.


title:
Protostellar Cloud Fragmentation and Inward Migration by Disk Capture as
  the Origin of Massive Exoplanets

abstract:
  A new model for the formation of Jovian planets is proposed. We consider
planets forming at large distances from a protostar (>100 AU) through direct
fragmentation of a gas cloud, by the same formation mechanism as wide stellar
and brown dwarf binaries. We model the gravitational evolution of a system of
these distant planets and a second population formed in a disk closer to the
star. We compute the typical closest approach of these planets to the star
(i.e., smallest pericenter) over the course of their evolution. When the
planets reach a pericenter within a gaseous disk surroundig the star, dynamical
friction from this disk slows down the planet at each plunge, causing its orbit
to be gradually circularized and made coplanar with the disk. After the disk
dissipates, a large fraction of these planets may be left at orbits small
enough to be detected in present radial velocity surveys. A brief analytic
derivation of the rate of orbital energy dissipation during these disk
crossings is presented. Observational tests of this model are discussed.


title: Shear Transport Coefficients from Gauge/Gravity Correspondence

abstract:
  We study the shear mode in the gauge/gravity correspondence at finite
temperature. First, we confirm the general formula for the shear viscosity in
an arbitrary background metric which includes a black hole in the fifth
dimension. We then derive a general formula for the shear mode relaxation time
which appears in the theory of relativistic dissipative fluid dynamics; it
agrees with known expressions in the limit of conformal fields. These results
may be useful in relativistic viscous fluid descriptions of high energy nuclear
collisions at RHIC and LHC.


title: Asymptotique des nombres de Betti des vari\'et\'es arithm\'etiques

abstract:
  We study the question of the growth of Betti numbers of certain arithmetic
varieties in tower of congruence coverings. In fact, our results are about
Siegel varieties and varieties associated to orthogonal groups. We explain how
a theorem of Waldspurger can be used to obtain lower and upper bound. Our
results are in the direction of conjectures made by Sarnak and Xue.


title:
Spectral luminosity indicators in SNe Ia - Understanding the R(SiII)
  line strength ratio and beyond

abstract:
  SNe Ia are good distance indicators because the shape of their light curves,
which can be measured independently of distance, varies smoothly with
luminosity. This suggests that SNe Ia are a single family of events. Similar
correlations are observed between luminosity and spectral properties. In
particular, the ratio of the strengths of the SiII \lambda 5972 and \lambda
6355 lines, known as R(SiII), was suggested as a potential luminosity
indicator. Here, the physical reasons for the observed correlation are
investigated. A Monte-Carlo code is used to construct a sequence of synthetic
spectra resembling those of SNe with different luminosities near B maximum. The
influence of abundances and of ionisation and excitation conditions on the
synthetic spectral features is investigated. The ratio R(SiII) depends
ssentially on the strength of SiII \lambda 5972, because SiII \lambda 6355 is
saturated. In less luminous objects, SiII \lambda 5972 is stronger because of a
rapidly increasing SiII/SiIII ratio. Thus, the correlation between R(SiII) and
luminosity is the effect of ionisation balance. The SiII \lambda 5972 line
itself may be the best spectroscopic luminosity indicator for SNe Ia, but all
indicators discussed show scatter which may be related to abundance
distributions.


title:
Computing invariants and semi-invariants by means of Frobenius Lie
  algebras

abstract:
  Let U(L) be the enveloping algebra of a finite dimensional Lie algebra L over
a field k of characteristic zero, Z(U(L)) its center and Sz(U(L)) its
semicenter. A sufficient condition is given in order for Sz(U(L)) to be a
polynomial algebra over k. Surprisingly, this condition holds for many Lie
algebras, especially among those for which the radical is nilpotent, in which
case Sz(U(L))=Z(U(L)). In particular, it allows the explicit description of
Z(U(L)) for more than half of all complex, indecomposable nilpotent Lie
algebras of dimension at most 7.


title: Solving period problems for minimal surfaces with the support function

abstract:
  In this paper we show how to bypass the usual difficulties in the analysis of
elliptic integrals that arise when solving period problems for minimal
surfaces. The method consists of replacing period problems with ordinary
Sturm-Liouville problems involving the support function. We give a practical
application by proving existence of the sheared Scherk-Karcher family of
surfaces numerically described by Wei. Moreover, we show that this family is
continuous, and both of its limit-members are the singly periodic genus-one
helicoid.


title:
Instanton representanton of Plebanski gravity. Gravitational coherent
  states

abstract:
  In this paper we show that the instanton representation of Plebanski gravity
exhibits a Hilbert space of harmonic oscillator-like coherent states. We put in
place the formalism and carry out the construction of the states, and we
elucidate on their physical interpretation. Additionally, we provide an
invertible map between the Ashtekar variables and this Hilbert space of states,
via the instanton representation. Finally, we compare and constrast our
formalism and some of our results with the corresponding ones in loop quantum
gravity.


title:
Structure and rheological properties of model microemulsion networks
  filled with nanoparticles

abstract:
  Model microemulsion networks of oil droplets stabilized by non ionic
surfactant and telechelic polymer C18-PEO(10k)-C18 have been studied for two
droplet-to-polymer size ratios. The rheological properties of the networks have
been measured as a function of network connectivity and can be described in
terms of simple percolation laws. The network structure has been characterised
by Small Angle Neutron Scattering. A Reverse Monte Carlo approach is used to
demonstrate the interplay of attraction and repulsion induced by the copolymer.
These model networks are then used as matrix for the incorporation of silica
nanoparticles (R=10nm), individual dispersion being checked by scattering. A
strong impact on the rheological properties is found for silica volume
fractions up to 9%.


title:
Instanton representation of Plebanski gravity XX. Minisuperspace
  quantization of gravity coupled to the Klein--Gordon scalar field

abstract:
  In this paper we quantize the Klein--Gordon scalar field coupled to gravity
in the instanton representation for spatially homogeneous variables. The
construction provides a well-defined Hilbert space of states for generic
self-interaction potential V, with a direct link to the semiclassical limit
below the Planck scale. Additionally, we compute the Hamilton's equations of
motion for this model, performing various consistency checks on the quantum
theory.


title:
Instanton representation of Plebanski gravity XXII. Minisuperspace
  quantization of gravity coupled to spin 1/2 fermionic fields

abstract:
  In this paper we carry out a quantization of gravity coupled to massless spin
1/2 fermions through the instanton representation of Plebanski gravity. We have
constructed a Hilbert space of states for this model, and we have computed the
Hamilton's equations of motion. The classical equations appear, at a
superficial level, to be consistent with the quantum dynamics of the theory.


title: The puzzling origin of the 6Li plateau

abstract:
  We discuss the 6Li abundance evolution within a hierarchical model of Galaxy
formation which correctly reproduces the [Fe/H] distribution of metal-poor halo
stars. Contrary to previous findings, we find that neither the level
(6Li/H=6x10^-12) nor the flatness of the 6Li distribution with [Fe/H] can be
reproduced under the most favourable conditions by any model in which 6Li
production is tied to a (data-constrained) Galactic star formation rate via
cosmic ray spallation. Thus, the origin of the plateau might be due to some
other early mechanism unrelated to star formation.


title:
Canonical analysis of cosmological topologically massive gravity at the
  chiral point

abstract:
  Wolfgang Kummer was a pioneer of two-dimensional gravity and a strong
advocate of the first order formulation in terms of Cartan variables. In the
present work we apply Wolfgang Kummer's philosophy, the `Vienna School
approach', to a specific three-dimensional model of gravity, cosmological
topologically massive gravity at the chiral point. Exploiting a new
Chern-Simons representation we perform a canonical analysis. The dimension of
the physical phase space is two per point, and thus the theory exhibits a local
physical degree of freedom, the topologically massive graviton.


title:
Radio continuum observations of the candidate supermassive black hole in
  the dwarf elliptical VCC128

abstract:
  The presence of black holes (BHs) at the centers of dwarf elliptical galaxies
(dEs) has been argued both theoretically and observationally. Using archival
HST/WFPC2 data, we found the Virgo cluster dwarf elliptical galaxy VCC128 to
harbor a binary nucleus, a feature that is usually interpreted as the
observable signature of a stellar disk orbiting a central massive black hole.
Debattista et al. 2006 estimated its mass M sim 6 10^6 - 5 10^7 Msun. One of
the most robust means of verifying the existence of a BH is radio continuum
and/or X-ray emission, however because of the deficiency of gas in dEs, radio
continuum emission forms the best option here. We have tried to detect the
X-band radio emission coming from the putative black hole in VCC128 when it
accretes gas from the surrounding ISM. While we made a positive 4 sigma
detection of a point source 4.63'' south-west of the binary nucleus, no
statistically significant evidence for emission associated with the nuclei
themselves was detected.
  This implies either that VCC128 has no massive central black hole, which
makes the nature of the binary nucleus hard to explain, or, if it has a central
black hole, that the physical conditions of the ISM (predominantly its density
and temperature) and/or of the surrounding accretion disk do not allow for
efficient gas accretion onto the black hole, making the quiescent black hole
very hard to detect at radio wavelengths.


title:
Intermediate Mass Black Hole Induced Quenching of Mass Segregation in
  Star Clusters

abstract:
  In many theoretical scenarios it is expected that intermediate-mass black
holes (IMBHs, with masses M ~ 100-10000 solar masses) reside at the centers of
some globular clusters. However, observational evidence for their existence is
limited. Several previous numerical investigations have focused on the impact
of an IMBH on the cluster dynamics or brightness profile. Here we instead
present results from a large set of direct N-body simulations including single
and binary stars. These show that there is a potentially more detectable IMBH
signature, namely on the variation of the average stellar mass between the
center and the half-light radius. We find that the existence of an IMBH
quenches mass segregation and causes the average mass to exhibit only modest
radial variation in collisionally relaxed star clusters. This differs from when
there is no IMBH. To measure this observationally requires high resolution
imaging at the level of that already available from the Hubble Space Telescope
(HST) for the cores of a large sample of galactic globular clusters. With a
modest additional investment of HST time to acquire fields around the
half-light radius, it will be possible to identify the best candidate clusters
to harbor an IMBH. This test can be applied only to globulars with a half-light
relaxation time less than or equal to 1 Gyr, which is required to guarantee
efficient energy equipartition due to two-body relaxation.


title: Two New Large Separation Gravitational Lenses from SDSS

abstract:
  We present discovery images, together with follow-up imaging and
spectroscopy, of two large separation gravitational lenses found by our survey
for wide arcs (the CASSOWARY). The survey exploits the multicolor photometry of
the Sloan Digital Sky Survey to find multiple blue components around red
galaxies. CASSOWARY~2 (or "the Cheshire Cat") is composed of two massive
early-type galaxies at z = 0.426 and 0.432 respectively lensing two background
sources, the first a star-forming galaxy at z = 0.97 and the second a high
redshift galaxy (z> 1.4). There are at least three images of the former source
and probably four or more of the latter, arranged in two giant arcs. The mass
enclosed within the larger arc of radius 11 arcsecs is about 33 x 10^{12} solar
masses. CASSOWARY~3 comprises an arc of three bright images of a z = 0.725
source, lensed by a foreground elliptical at z = 0.274. The radius of the arc
is about 4 arcsecs and the enclosed mass is 2.5 x 10^{12} solar masses.
Together with earlier discoveries like the Cosmic Horseshoe and the 8 O'Clock
Arc, these new systems, with separations intermediate between the arcsecond
separation lenses of typical strong galaxy lensing and the larger separation
cluster lenses, probe the very high end of the galaxy mass function.


title: Galaxy morphology in the LambdaCDM cosmology

abstract:
  We investigate the origins of galaxy morphology (defined by bulge-to-total
K-band luminosity) in the LambdaCDM cosmology using two galaxy formation models
,based on the Millennium simulation, by Bower et al. (the Durham model) and De
Lucia & Blaizot (the MPA model). There are many similarities, but also
fundamental disagreements in the predictions of the two models for galaxy
morphology. For example, taking into account uncertainties in the available
observational data, both produce a realistic morphological mix today, but its
evolution is very different. A main cause of this and other differences is the
treatment of disk instabilities which play a more prominent role in the Durham
model. Our analysis confirms previous theoretical predictions that elliptical
galaxies form most of their stars before the bulk of the galaxy is assembled.
Spirals tend to have later `assembly' times as a consequence of in-situ star
formation. With the exception of the brightest ellipticals (stellar mass >
2.5e11 M_sun/h), we find that major mergers are not the primary mechanism by
which most spheroids (ellipticals and spiral bulges) assemble their mass. In
fact, the majority of ellipticals (and the overwhelming majority of spirals)
never experience a major merger (above the resolution limit of our simulation.)
Most ellipticals and spiral bulges acquire their stellar mass through minor
mergers or disk instabilities. These conclusions are common to both models. The
rotation properties of spheroids may help to constrain the importance of disk
instabilities in these models.


title: A new method of measuring the cluster peculiar velocity power spectrum

abstract:
  We propose to use spatial correlations of the kinetic Sunyaev-Zeldovich (KSZ)
flux as an estimator of the peculiar velocity power spectrum. In contrast with
conventional techniques, our new method does not require measurements of the
thermal SZ signal or the X-ray temperature. Moreover, this method has the
special advantage that the expected systematic errors are always sub-dominant
to statistical errors on all scales and redshifts of interest. We show that
future large sky coverage KSZ surveys may allow a peculiar velocity power
spectrum estimates of an accuracy reaching ~10%.


title:
Spectral curves, emergent geometry, and bubbling solutions for Wilson
  loops

abstract:
  We study the supersymmetric circular Wilson loops of N=4 super Yang-Mills in
large representations of the gauge group. In particular, we obtain the spectral
curves of the matrix model which captures the expectation value of the loops.
These spectral curves are then proven to be precisely the hyperelliptic
surfaces that characterize the bubbling solutions dual to the Wilson loops,
thus yielding an example of a geometry emerging from an eigenvalue
distribution. We finally discuss the Wilson loop expectation value from the
matrix model and from supergravity.


title:
Theory of spin nematic to spin-Peierls quantum phase transition in
  ultracold spin-1 atoms in optical lattices

abstract:
  We present a theory of the anisotropy tuned quantum phase transition between
spin nematic and spin-Peierls phases in S=1 systems with significant
bi-quadratic exchange interactions. Based on quantum Monte Carlo studies on
finite size systems, [K. Harada et al., J. Phys. Soc. Jpn. 76, 013703 (2007)]
it has been proposed that this phase transition is second order with new
deconfined fractional excitations that are absent in either of the two phases
[T. Grover and T. Senthil, Phys. Rev. Lett. 98, 247202 (2007)]. The possibility
of a weak first order transition, however, cannot be ruled out. To elucidate
the nature of the transition, we construct a large-N SO(3N) model for this
phase transition and find in the $N\to\infty$ limit that the transition is
generically of first order. Furthermore, we find a critical point in the 1D
limit, where two transition lines, separating spin nematic, ferromagnetic, and
spin-Peierls phases, meet. Our study indicates that the spin nematic phase is
absent in 1D, while its correlation length diverges at the critical point.
Predictions for $^{23}$Na atoms trapped in an optical lattice, where this
quantum phase transition naturally arises, are discussed.


title:
Spin polarized transport driven by square voltage pulses in a quantum
  dot system

abstract:
  We calculate current, spin current and tunnel magnetoresistance (TMR) for a
quantum dot coupled to ferromagnetic leads in the presence of a square wave of
bias voltage. Our results are obtained via time-dependent nonequilibrium Green
function. Both parallel and antiparallel lead magnetization alignments are
considered. The main findings include a wave of spin accumulation and spin
current that can change sign as the time evolves, spikes in the TMR signal and
a TMR sign change due to an ultrafast switch from forward to reverse current in
the emitter lead.


title: FeynRules - Feynman rules made easy

abstract:
  In this paper we present FeynRules, a new Mathematica package that
facilitates the implementation of new particle physics models. After the user
implements the basic model information (e.g. particle content, parameters and
Lagrangian), FeynRules derives the Feynman rules and stores them in a generic
form suitable for translation to any Feynman diagram calculation program. The
model can then be translated to the format specific to a particular Feynman
diagram calculator via FeynRules translation interfaces. Such interfaces have
been written for CalcHEP/CompHEP, FeynArts/FormCalc, MadGraph/MadEvent and
Sherpa, making it possible to write a new model once and have it work in all of
these programs. In this paper, we describe how to implement a new model,
generate the Feynman rules, use a generic translation interface, and write a
new translation interface. We also discuss the details of the FeynRules code.


title: The Quantum Internet

abstract:
  Quantum networks offer a unifying set of opportunities and challenges across
exciting intellectual and technical frontiers, including for quantum
computation, communication, and metrology. The realization of quantum networks
composed of many nodes and channels requires new scientific capabilities for
the generation and characterization of quantum coherence and entanglement.
Fundamental to this endeavor are quantum interconnects that convert quantum
states from one physical system to those of another in a reversible fashion.
Such quantum connectivity for networks can be achieved by optical interactions
of single photons and atoms, thereby enabling entanglement distribution and
quantum teleportation between nodes.


title: Jet and prolongation spaces

abstract:
  The notion of prolongation of an algebraic variety is developed in an
abstract setting that generalises the difference and (Hasse) differential
contexts. An interpolating map that compares the prolongation spaces with
algebraic jet spaces is introduced and studied.


title:
Planet Migration and Disk Destruction due to Magneto-Centrifugal Stellar
  Winds

abstract:
  This paper investigates the influence of magneto-centrifugally driven or
simply magnetic winds of rapidly-rotating, strongly-magnetized T Tauri stars in
causing the inward or outward migration of close-in giant planets. The
azimuthal ram pressure of the magnetized wind acting on the planet tends to
increase the planet's angular momentum and cause outward migration if the
star's rotation period $P_*$ is less than the planet's orbital period $P_p$. In
the opposite case, $P_* > P_p$, the planet migrates inward. Thus, planets
orbiting at distances larger (smaller) than $0.06 {\rm AU}(P_*/5{\rm d})^{2/3}$
tend to be pushed outward (inward), where $P_*$ is the rotation period of the
star assumed to have the mass of the sun. The magnetic winds are likely to
occur in T Tauri stars where the thermal speed of the gas close to the star is
small, where the star's magnetic field is strong, and where the star rotates
rapidly. The time-scale for appreciable radial motion of the planet is
estimated as $\sim 2 - 20$ Myr. A sufficiently massive close-in planet may
cause tidal locking and once this happens the radial migration due to the
magnetic wind ceases. The magnetic winds are expected to be important for
planet migration for the case of a multipolar magnetic field rather than a
dipole field where the wind is directed away from the equatorial plane and
where a magnetospheric cavity forms. The influence of the magnetic wind in
eroding and eventually destroying the accretion disk is analyzed. A momentum
integral is derived for the turbulent wind/disk boundary layer and this is used
to estimate the disk erosion time-scale as $\sim 1-10^2$ Myr, with the lower
value favored.


title:
Hidden Orbital Liquid State Within Ferromagnetically Ordered Metallic
  SrRuO3

abstract:
  We have experimentally found related anomalies in electrical resistivity, dc
and ac magnetic susceptibility, appearing deeply within ferromagnetically
ordered state in SrRuO3. Lack of Jahn-Teller distortion in this regime rules
out conventional orbital order, forcing one to describe these in terms of an
orbital liquid ground state coexisting with ferromagnetic spin order. We
suggest that weak spin-orbit coupling in such an unusual state underpins the
observed anomalies.


title: A Less Conservative Circle Criterion

abstract:
  A weak form of the Circle Criterion for Lur'e systems is stated. The result
allows prove global boundedness of all system solutions. Moreover such a result
can be employed to enlarge the set of nonlinearities for which the standard
Circle Criterion can guarantee absolute stability.


title: The Secrecy Rate Region of the Broadcast Channel

abstract:
  In this paper, we consider a scenario where a source node wishes to broadcast
two confidential messages for two respective receivers, while a wire-tapper
also receives the transmitted signal. This model is motivated by wireless
communications, where individual secure messages are broadcast over open media
and can be received by any illegitimate receiver. The secrecy level is measured
by equivocation rate at the eavesdropper. We first study the general
(non-degraded) broadcast channel with confidential messages. We present an
inner bound on the secrecy capacity region for this model. The inner bound
coding scheme is based on a combination of random binning and the
Gelfand-Pinsker bining. This scheme matches the Marton's inner bound on the
broadcast channel without confidentiality constraint. We further study the
situation where the channels are degraded. For the degraded broadcast channel
with confidential messages, we present the secrecy capacity region. Our
achievable coding scheme is based on Cover's superposition scheme and random
binning. We refer to this scheme as Secret Superposition Scheme. In this
scheme, we show that randomization in the first layer increases the secrecy
rate of the second layer. This capacity region matches the capacity region of
the degraded broadcast channel without security constraint. It also matches the
secrecy capacity for the conventional wire-tap channel. Our converse proof is
based on a combination of the converse proof of the conventional degraded
broadcast channel and Csiszar lemma. Finally, we assume that the channels are
Additive White Gaussian Noise (AWGN) and show that secret superposition scheme
with Gaussian codebook is optimal. The converse proof is based on the
generalized entropy power inequality.


title: The MiniBooNE Detector

abstract:
  The MiniBooNE neutrino detector was designed and built to look for
muon-neutrino to electron-neutrino oscillations in the mixing parameter space
region where the LSND experiment reported a signal. The MiniBooNE experiment
used a beam energy and baseline that were an order of magnitude larger than
those of LSND so that the backgrounds and systematic errors would be completely
different. This paper provides a detailed description of the design, function,
and performance of the MiniBooNE detector.


title: The cosmology of the Divine Comedy

abstract:
  Since the time of ancient civilizations, cosmology had a privileged place
within the various artistic and literary manifestations. The Divine Comedy by
Dante Alighieri, one of the masterpieces in literature and thought of the
Western World, is organized on the image of the cosmos of the XIII century,
which is analyzed in this article.


title: Some examples of compact composition operators on $H^2$

abstract: To appear in J. Functional Analysis


title:
A criterion of weak compactness for operators on subspaces of Orlicz
  spaces

abstract: To appear in J. Funct. Spaces and Appl.


title:
The Quantum Capacitor Detector: A Single Cooper Pair Box Based Readout
  for Pair Breaking Photo-detectors

abstract:
  We propose a sensitive new detector based on Cooper pair breaking in a
superconductor. The quantum capacitor detector (QCD) exploits the extraordinary
sensitivity of superconducting single-electron devices to the presence of
quasiparticles generated by pair-breaking photons. This concept would enable
single-photon detection at far-IR and sub-millimeter frequencies with detector
sensitivities that exceed that of transition-edge-sensor bolometers (TES),
kinetic inductance detectors (KID), and superconducting tunnel junction
detectors (STJ). The detectors we propose are based on the single Cooper pair
box (SCB), a mesoscopic superconducting device that has been successfully
developed at JPL for applications in quantum computing. This concept allows for
frequency multiplexing of a large number of pixels using a single RF line, and
does not require individual bias of each pixel. The QCD is ideal for the
sensitive spectrographs considered for upcoming cold space telescopes, such as
BLISS for SPICA in the coming decade, and for the more ambitious instruments
for the SAFIR / CALISTO and SPIRIT / SPECS missions envisioned for the 2020
decade. These missions require large detector arrays (> 10,000 elements) which
are limited by astrophysical background noise, corresponding to a
noise-equivalent power (NEP) as low as 2x10-20 W / Hz1/2. Given its intrinsic
response time, the QCD could also be used for energy-resolved visible photon
detection, with estimated energy resolution > 100, enabling imaging
low-resolution spectroscopy with an array of detectors.


title: Compact composition operators on $H^2$ and Hardy-Orlicz spaces

abstract:
  We compare the compactness of composition operators on $H^2$ and on
Orlicz-Hardy spaces $H^\Psi$. We show in particular that exists an Orlicz
function $\Psi$ such that $H^{3+\eps} \subseteq H^\Psi \subseteq H^3$ for every
$\eps >0$, and a composition operator $C_\phi$ which is compact on $H^3$ and on
$H^{3+\eps}$, but not compact on $H^\Psi$.


title:
Characterization of Collective Gaussian Attacks and Security of
  Coherent-State Quantum Cryptography

abstract:
  We provide a simple description of the most general collective Gaussian
attack in continuous-variable quantum cryptography. In the scenario of such
general attacks, we analyze the asymptotic secret-key rates which are
achievable with coherent states, joint measurements of the quadratures and
one-way classical communication.


title: More Constructions for Tur\'an's (3, 4)-Conjecture

abstract:
  For Tur\'an's (3, 4)-conjecture, in the case of n = 3k+1 vertices,
(.5)6^{k-1} non-isomorphic complexes are constructed that attain the
conjecture. In the case of n = 3k+2 vertices, 6^{k-1} non-isomorphic complexes
are constructed that attain the conjecture.


title: Analytical Model of Spin-Polarized Semiconductor Lasers

abstract:
  We formulate an analytical model for vertical-cavity surface-emitting lasers
(VCSELs) with injection (pump) of spin-polarized electrons. Our results for two
different modes of carrier recombination allow for a systematic analysis of the
operational regimes of the spin-VCSELs. We demonstrate that threshold reduction
by electrically-pumped spin-polarized carriers can be larger than previously
assumed possible. Near the threshold, such VCSELs can act as effective
non-linear filters of circularly-polarized light, owing to their spin-dependent
gain.


title: Agnostically Learning Juntas from Random Walks

abstract:
  We prove that the class of functions g:{-1,+1}^n -> {-1,+1} that only depend
on an unknown subset of k<<n variables (so-called k-juntas) is agnostically
learnable from a random walk in time polynomial in n, 2^{k^2}, epsilon^{-k},
and log(1/delta). In other words, there is an algorithm with the claimed
running time that, given epsilon, delta > 0 and access to a random walk on
{-1,+1}^n labeled by an arbitrary function f:{-1,+1}^n -> {-1,+1}, finds with
probability at least 1-delta a k-junta that is (opt(f)+epsilon)-close to f,
where opt(f) denotes the distance of a closest k-junta to f.


title: Teleportation using squeezed single photons

abstract:
  We present an analysis of squeezed single photon states as a resource for
teleportation of coherent state qubits and propose proof-of-principle
experiments for the demonstration of coherent state teleportation and
entanglement swapping. We include an analysis of the squeezed vacuum as a
simpler approximation to small-amplitude cat states. We also investigate the
effects of imperfect sources and inefficient detection on the proposed
experiments.


title: Partition Functions for Membrane Theories

abstract:
  Partition functions for M2-brane theories in various backgrounds are
computed. We consider in particular configurations of membranes at orbifold
singularities preserving N=5 or N=6 supersymmetry. The worldvolume membrane
theory for some of these configurations has been recently constructed in terms
of N=6 Chern-Simons theories. The detailed structure of the partition functions
as well as their transformation rules under the R-symmetry are explicitly
computed using the Plethystic Programme.


title: The Charney-Davis conjecture for certain subdivisions of spheres

abstract:
  Notions of sesquiconstructible complexes and odd iterated stellar
subdivisions are introduced, and some of their basic properties are verified.
The Charney-Davis conjecture is then proven for odd iterated stellar
subdivisions of sesquiconstructible balls and spheres.


title: Quantum Coding with Entanglement

abstract:
  Quantum error-correcting codes will be the ultimate enabler of a future
quantum computing or quantum communication device. This theory forms the
cornerstone of practical quantum information theory. We provide several
contributions to the theory of quantum error correction--mainly to the theory
of "entanglement-assisted" quantum error correction where the sender and
receiver share entanglement in the form of entangled bits (ebits) before
quantum communication begins. Our first contribution is an algorithm for
encoding and decoding an entanglement-assisted quantum block code. We then give
several formulas that determine the optimal number of ebits for an
entanglement-assisted code. The major contribution of this thesis is the
development of the theory of entanglement-assisted quantum convolutional
coding. A convolutional code is one that has memory and acts on an incoming
stream of qubits. We explicitly show how to encode and decode a stream of
information qubits with the help of ancilla qubits and ebits. Our
entanglement-assisted convolutional codes include those with a
Calderbank-Shor-Steane structure and those with a more general structure. We
then formulate convolutional protocols that correct errors in noisy
entanglement. Our final contribution is a unification of the theory of quantum
error correction--these unified convolutional codes exploit all of the known
resources for quantum redundancy.


title: Hall coefficient and Hc2 in underdoped LaFeAsO0.95F0.05

abstract:
  The electrical resistivity and Hall coefficient of LaFeAsO0.95F0.05
polycrystalline samples were measured in pulsed magnetic fields up to m0H = 60
T from room temperature to 1.5 K. The resistance of the normal state shows a
negative temperature coefficient (dr/dT < 0) below 70 K for this composition,
indicating insulating ground state in underdoped LaFeAsO system in contrast to
heavily doped compound. The charge carrier density obtained from Hall effect
can be described as constant plus a thermally activated term with an energy gap
DE = 630 K. Upper critical field, Hc2, estimated from resistivity measurements,
exceeds 75 T with zero-field Tc = 26.3 K, suggesting an unconventional nature
for superconductivity.


title: Universal entangler with photon pairs in arbitrary states

abstract:
  We propose a setup that transforms a photon pair in arbitrary rank-four mixed
state, which could also be unknown, to a Bell state. The setup involves two
linear optical circuits processing the individual photons and a parity gate
working with weak cross-Kerr nonlinearity. By the photon number resolving
detection on one of the output quantum bus or communication beams, the setup
will realize a near deterministic transformation to a Bell state for every
entangling attempt. With the simple threshold detectors, on the other hand, the
system can still reach a considerable success probability of 0.5 per try. The
decoherence effect caused by photon absorption losses in the operation is also
discussed.


title: Resonant Analytic Fields Applied to Generic Multi-state Systems

abstract:
  Rotating-wave approximation and its validity in multi-state quantum systems
are studied through analytic approach. Their applicability is also verified
from the viewpoint of generic states by the use of direct numerical
integrations of the Schroedinger equation. First, we introduce an extension of
the rotating-wave approximation for multi-state systems. Under an assumption
that a smooth transition is induced by the optimal field, we obtain three types
of analytic control fields and demonstrate their validity and deficiency for
generic systems represented by random matrices. Through the comparison, we
conclude that the analytic field based on our coarse-grained approach
outperforms the other ones for generic quantum systems with a large number of
states. Finally, the further extension of the analytic field is introduced for
realistic chaotic systems and its validity is shown in banded random matrix
systems.


title:
Electromagnetically-Induced-Transparency-Like Effect in the Degenerate
  Triple-Resonant Optical Parametric Amplifier

abstract:
  We investigate experimentally the absorptive and dispersive properties of
triple-resonant optical parametric amplifier OPA for the degenerate subharmonic
field. In the experiment, the subharmonic field is utilized as the probe field
and the harmonic wave as the pump field. We demonstrate that EIT-like effect
can be simulated in the triple-resonant OPA when the cavity line-width for the
harmonic wave is narrower than that for the subharmonic field. However, this
phenomenon can not be observed in a double-resonant OPA. The narrow
transparency window appears in the reflected field. Especially, in the measured
dispersive spectra of triple-resonant OPA, a very steep variation of the
dispersive profile of the subharmonic field is observed, which can result in a
slow light as that observed in atomic EIT medium.


title: Center vortices and the quark propagator in SU(2) gauge theory

abstract:
  We study the behavior of the AsqTad quark propagator in Landau gauge on
quenched SU(2) gauge configurations under the removal of center vortices. In
contrast to recent results in SU(3), we clearly see the infrared enhancement of
the mass function disappear if center vortices are removed, a sign of the
intimate relation between center vortices and chiral symmetry breaking in SU(2)
gauge-field theory. These results provide a benchmark with which to interpret
the SU(3) results. In addition, we consider vortex-only configurations. On
those, the quark dressing function behaves roughly as on the full
configurations, and the mass function picks up an almost linear momentum
dependence.


title: A strong antidiamond principle compatible with CH

abstract:
  A strong antidiamond principle (*c) is shown to be consistent with CH. This
principle can be stated as a "P-ideal dichotomy": every P-ideal on omega-1
(i.e. an ideal that is sigma-directed under inclusion modulo finite) either has
a closed unbounded subset of omega-1 locally inside of it, or else has a
stationary subset of omega-1 orthogonal to it. We rely on Shelah's theory of
parameterized properness for NNR iterations, and make a contribution to the
theory with a method of constructing the properness parameter simultaneously
with the iteration. Our handling of the application of the NNR iteration theory
involves definability of forcing notions in third order arithmetic, analogous
to Souslin forcing in second order arithmetic.


title: Localized Spanners for Wireless Networks

abstract:
  We present a new efficient localized algorithm to construct, for any given
quasi-unit disk graph G=(V,E) and any e > 0, a (1+e)-spanner for G of maximum
degree O(1) and total weight O(w(MST)), where w(MST) denotes the weight of a
minimum spanning tree for V. We further show that similar localized techniques
can be used to construct, for a given unit disk graph G = (V, E), a planar
Cdel(1+e)(1+pi/2)-spanner for G of maximum degree O(1) and total weight
O(w(MST)). Here Cdel denotes the stretch factor of the unit Delaunay
triangulation for V. Both constructions can be completed in O(1) communication
rounds, and require each node to know its own coordinates.