title:
The Science Impact of Astronomy PhD Granting Departments in the United
  States

abstract:
  The scientific impact of the research of 36 astronomy PhD granting
departments is measured and ranked here. Because of the complex nature of
Universities, this study looks at the Universities in two ways; first analyzing
the impact of the published work over a 10 year period of the Department which
grants the PhD and; second, looking at the impact of the published work as a
whole including Laboratories, Centers, and Facilities. The Universities
considered in the study are drawn from the 1992 NRC study on Programs of
Research, Doctorate in Astrophysics and Astronomy with three Universities
added. Johns Hopkins, Michigan State, and Northwestern all host substantial
astronomical research within their Departments of Physics and Astronomy and so
are included here. The first method of measuring impact concentrates on tenured
and tenured track faculty, with the top quartile being 1. Caltech, 2. UC Santa
Cruz, 3. Princeton, 4. Harvard, 5. U Colorado, Boulder, 6. SUNY, Stony Brook,
7. Johns Hopkins, 8. Penn State, and 9. U Michigan, Ann Arbor. The second
method additionally includes "soft money" scientists in research and adjunct
faculty positions, with the top quartile being 1. UC Santa Cruz, 2. Princeton,
3. Johns Hopkins 4. Penn State, 5. SUNY Stony Brook, 6. U Michigan, Ann Arbor,
7. New Mexico State, 8. UMass, Amherst, and 9. U Virginia. Both methods reveal
important aspects of Universities, representing both the depth and the breadth
of the science available at the University. Finally, a comparison is made of
the total articles published in the 10 year period, both from the departments
alone and from the larger universities. Three Universities have both impact
index in the top quartile, and have more than 1000 publications in a decade; UC
at Santa Cruz, Princeton, and Johns Hopkins.


title:
Maximally symmetric spaces in Brans-Dicke theory and the cosmological
  constant

abstract:
  In this note we discuss a toy model in which the value of the effective
cosmological constant is associated with a symmetry properties of the vacuum
background solution and defined by the model parameter associated with a scalar
field non-minimally coupled to gravity. Although the parameters in the model
seem to have unrealistic values to account for the present value of the
cosmological constant, the model demonstrates a possible alternative way it can
arise.


title: Accurate estimators of power spectra in N-body simulations

abstract:
  abridged] A method to rapidly estimate the Fourier power spectrum of a point
distribution is presented. This method relies on a Taylor expansion of the
trigonometric functions. It yields the Fourier modes from a number of FFTs,
which is controlled by the order N of the expansion and by the dimension D of
the system. In three dimensions, for the practical value N=3, the number of
FFTs required is 20. We apply the method to the measurement of the power
spectrum of a periodic point distribution that is a local Poisson realization
of an underlying stationary field. We derive explicit analytic expression for
the spectrum, which allows us to quantify--and correct for--the biases induced
by discreteness and by the truncation of the Taylor expansion, and to bound the
unknown effects of aliasing of the power spectrum. We show that these aliasing
effects decrease rapidly with the order N. The only remaining significant
source of errors is reduced to the unavoidable cosmic/sample variance due to
the finite size of the sample. The analytical calculations are successfully
checked against a cosmological N-body experiment. We also consider the initial
conditions of this simulation, which correspond to a perturbed grid. This
allows us to test a case where the local Poisson assumption is incorrect. Even
in that extreme situation, the third-order Fourier-Taylor estimator behaves
well. We also show how to reach arbitrarily large dynamic range in Fourier
space (i.e., high wavenumber), while keeping statistical errors in control, by
appropriately "folding" the particle distribution.


title:
Predicting scattering properties of ultracold atoms: adiabatic
  accumulated phase method and mass scaling

abstract:
  Ultracold atoms are increasingly used for high precision experiments that can
be utilized to extract accurate scattering properties. This calls for a
stronger need to improve on the accuracy of interatomic potentials, and in
particular the usually rather inaccurate inner-range potentials. A boundary
condition for this inner range can be conveniently given via the accumulated
phase method. However, in this approach one should satisfy two conditions,
which are in principle conflicting, and the validity of these approximations
comes under stress when higher precision is required. We show that a better
compromise between the two is possible by allowing for an adiabatic change of
the hyperfine mixing of singlet and triplet states for interatomic distances
smaller than the separation radius. A mass scaling approach to relate
accumulated phase parameters in a combined analysis of isotopically related
atom pairs is described in detail and its accuracy is estimated, taking into
account both Born-Oppenheimer and WKB breakdown. We demonstrate how numbers of
singlet and triplet bound states follow from the mass scaling.


title: CRASH2: colored packets and other updates

abstract:
  In this paper we report on the improvements implemented in the cosmological
radiative transfer code CRASH. In particular we present a new multi-frequency
algorithm for spectra sampling which makes use of colored photon packets: we
discuss the need for the multi-frequency approach, describe its implementation
and present the improved CRASH performance in reproducing the effects of
ionizing radiation with an arbitrary spectrum. We further discuss minor changes
in the code implementation which allow for more efficient performance and an
increased precision.


title: Science with the World Space Observatory - Ultraviolet

abstract:
  The World Space Observatory-Ultraviolet (WSO-UV) will provide access to the
UV range during the next decade. The instrumentation on board will allow to
carry out high resolution imaging, high sensitivity imaging, high resolution
(R~55000) spectroscopy and low resolution (R~2500) long slit spectroscopy. In
this contribution, we briefly outline some of the key science issues that
WSO-UV will address during its lifetime. Among them, of special interest are:
the study of galaxy formation and the intergalactic medium; the astronomical
engines; the Milky Way formation and evol ution, and the formation of the Solar
System and the atmospheres of extrasolar p lanets.


title:
A Pedagogical Discussion Concerning the Gravitational Energy Radiated by
  Keplerian Systems

abstract:
  We first discuss the use of dimensional arguments (and of the quadrupolar
emission hypothesis) in the derivation of the gravitational power radiated on a
circular orbit. Then, we show how to simply obtain the instantaneous power
radiated on a general Keplerian orbit by approximating it locally by a circle.
This allows recovering with a good precision, in the case of an ellipse, the
highly non trivial dependence on the eccentricity of the average power given by
general relativity. The whole approach is understandable by undergraduate
students.


title: Categories. Beginning Course (in Russian)

abstract:
  This is a short textbook on Category Theory for Russian speaking students. It
consists of three chapters: Categories and Functors, Representable Functors
(including Adjoint Functors and (Co)limits) and Tensor Categories.


title: Single and low-lying states dominance in two-neutrino double-beta decay

abstract:
  A theoretical analysis of the single-state dominance hypothesis for the
two-neutrino double-beta decay rates is performed on the examples of the
double-beta decays of 100Mo, 116Cd, and 128Te. We also test the validity of an
extended low-lying-state dominance that takes into account the contributions of
the low-lying excited states in the intermediate nucleus to the double-beta
decay rates. This study has been accomplished for all the double-beta emitters
for which we have experimental information on their half-lives. The theoretical
framework is a proton-neutron quasiparticle random-phase approximation based on
a deformed Skyrme Hartree-Fock mean field with pairing correlations. Our
calculations indicate that there are not clear evidences for single- or
low-lying-state dominance in the two-neutrino double-beta decay. Finally, we
investigate the single electron energy distributions of the outgoing electrons
in the double-beta decay processes with an exact treatment of the energy
denominators, which could help to a more comprehensive analysis of NEMO-3 data.


title: Energy-resolved spatial inhomogeneity of disordered Mott systems

abstract:
  We investigate the effects of weak to moderate disorder on the T=0 Mott
metal-insulator transition in two dimensions. Our model calculations
demonstrate that the electronic states close to the Fermi energy become more
spatially homogeneous in the critical region. Remarkably, the higher energy
states show the opposite behavior: they display enhanced spatial inhomogeneity
precisely in the close vicinity to the Mott transition. We suggest that such
energy-resolved disorder screening is a generic property of disordered Mott
systems.


title: Can one measure timelike Compton scattering at LHC ?

abstract:
  Exclusive photoproduction of dileptons, gamma N->e+e-N, is and will be
measured in ultraperipheral collisions at hadron colliders, such as the
Tevatron, RHIC and the LHC . We demonstrate that the timelike deeply virtual
Compton scattering (TCS) mechanism gamma q -> e+e- q where the lepton pair
comes from the subprocess gamma q -> gamma* q dominates in some accessible
kinematical regions, thus opening a new way to study generalized parton
distributions (GPD) in the nucleon. High energy kinematics enables to probe
parton distributions at small skewedness. This subprocess interferes at the
amplitude level with the pure QED subprocess gamma gamma* -> e+e- where the
virtual photon is radiated from the nucleon.


title:
Two-component galaxy models: the effect of density profile at large
  radii on the phase-space consistency

abstract:
  It is well known that the density and anisotropy profile in the inner regions
of a stellar system with positive phase-space distribution function are not
fully independent. Here we study the interplay between density profile and
orbital anisotropy at large radii in physically admissible (consistent) stellar
systems. The analysis is carried out by using two-component (n-gamma,gamma_1)
spherical self-consistent galaxy models, in which one density distribution
follows a generalized gamma profile with external logarithmic slope n, and the
other a standard gamma_1 profile (with external slope 4). The necessary and
sufficient conditions for phase-space consistency are determined analytically,
also in presence of a dominant massive central black hole, and the analytical
phase-space distribution function of (n-gamma,1) models, and of n-gamma models
with a central black hole, is derived for gamma=0,1,2. It is found that the
density slope in the external regions of a stellar system can play an important
role in determining the amount of admissible anisotropy: in particular, for
fixed density slopes in the central regions, systems with a steeper external
density profile can support more radial anisotropy than externally flatter
models. This is quantified by an inequality formally identical to the ``cusp
slope-central anisotropy'' theorem (An & Evans 2006), relating at all radii
(and not just at the center) the density logarithmic slope and the anisotropy
indicator in all Osipkov-Merritt systems [Abridged].


title: Dipole emission and coherent transport in random media I

abstract:
  This is the first of a series of papers devoted to develop a microscopical
approach to the dipole emission process and its relation to coherent transport
in random media. In this Letter, we deduce general expressions for the decay
rate of spontaneous emitters and the power emission of induced dipoles embedded
in homogenous dielectric media. We derive formulae which apply generically to
virtual cavities and, in the continuum approximation, to small real cavities.

categories: physics.optics cond-mat.dis-nn cond-mat.mes-hall physics.bio-ph


title: Optical orientation in bipolar spintronic devices

abstract:
  Optical orientation is a highly efficient tool for the generation of
nonequilibrium spin polarization in semiconductors. Combined with
spin-polarized transport it offers new functionalities for conventional
electronic devices, such as pn junction bipolar diodes or transistors. In
nominally nonmagnetic junctions optical orientation can provide a source for
spin capacitance--the bias-dependent nonequilibrium spin accumulation--or for
spin-polarized current in bipolar spin-polarized solar cells. In magnetic
junctions, the nonequilibrium spin polarization generated by spin orientation
in a proximity of an equilibrium magnetization gives rise to the spin-voltaic
effect (a realization of the Silsbee-Johnson coupling), enabling efficient
control of electrical properties such as the I-V characteristics of the
junctions by magnetic and optical fields. This article reviews the main results
of investigations of spin-polarized and magnetic pn junctions, from spin
capacitance to the spin-voltaic effect.


title:
Energy Benefit of Network Coding for Multiple Unicast in Wireless
  Networks

abstract:
  We show that the maximum possible energy benefit of network coding for
multiple unicast on wireless networks is at least 3. This improves the
previously known lower bound of 2.4 from [1].


title: Massive hidden photons as lukewarm dark matter

abstract:
  We study the possibility that a keV-MeV mass hidden photon (HP), i.e. a
hidden sector U(1) gauge boson, accounts for the observed amount of dark
matter. We focus on the case where the HP interacts with the standard model
sector only through kinetic mixing with the photon. The relic abundance is
computed including all relevant plasma effects into the photon's self-energy,
which leads to a resonant yield almost independent of the HP mass. The HP can
decay into three photons. Moreover, if light enough it can be copiously
produced in stars. Including bounds from cosmic photon backgrounds and stellar
evolution, we find that the hidden photon can only give a subdominant
contribution to the dark matter. This negative conclusion may be avoided if
another production mechanism besides kinetic mixing is operative.


title:
On the evolution of the Gamma- and X-ray luminosities of Pulsar Wind
  Nebulae

abstract:
  Pulsar wind nebulae are a prominent class of very high energy (E > 0.1 TeV)
Galactic sources. Their Gamma-ray spectra are interpreted as due to inverse
Compton scattering of ultrarelativistic electrons on the ambient photons,
whereas the X-ray spectra are due to synchrotron emission. We investigate the
relation between the Gamma- and-X-ray emission and the pulsars' spin-down
luminosity and characteristic age. We find that the distance-independent Gamma-
to X-ray flux ratio of the nebulae is inversely proportional to the spin-down
luminosity, (\propto \dot{E}^-1.9), while it appears proportional to the
characteristic age, (\propto tau_c^2.2), of the parent pulsar. We interpret
these results as due to the evolution of the electron energy distribution and
the nebular dynamics, supporting the idea of so-called relic pulsar wind
nebulae. These empirical relations provide a new tool to classify unidentified
diffuse Gamma-ray sources and to estimate the spin-down luminosity and
characteristic age of rotation powered pulsars with no detected pulsation from
the X- and Gamma-ray properties of the associated pulsar wind nebulae. We apply
these relations to predict the spin-down luminosity and characteristic age of
four (so far unpulsing) candidate pulsars associated to wind nebulae.


title: Coupling of nitrogen-vacancy centers in diamond to a GaP waveguide

abstract:
  The optical coupling of guided modes in a GaP waveguide to nitrogen-vacancy
(NV) centers in diamond is demonstrated. The electric field penetration into
diamond and the loss of the guided mode are measured. The results indicate that
the GaP-diamond system could be useful for realizing coupled microcavity-NV
devices for quantum information processing in diamond.


title: The Environmental Influence on the Evolution of Local Galaxies

abstract:
  The results of an Halpha photometric survey of 30 dwarf galaxies of various
morphologies in the Centaurus A and Sculptor groups are presented. Of these 30,
emission was detected in 13: eight are of late-type, two are early-type and
three are of mixed-morphology. The typical flux detection limit of 2e-16 erg
s-1 cm-2, translates into a Star Formation Rate (SFR) detection limit of 4e-6
M_sol yr-1 . In the light of these results, the morphology-density relation is
reexamined: It is shown that, despite a number of unaccounted parameters, there
are significant correlations between the factors determining the morphological
type of a galaxy and its environment. Dwarf galaxies in high density regions
have lower current SFR and lower neutral gas content than their low density
counterparts, confirming earlier results from the Local Group and other denser
environments. The effect of environment is also seen in the timescale formed
from the ratio of blue luminosity to current SFR - dwarfs in higher density
environments have larger values, indicating relatively higher past average SFR.
The influence of environment extends very far and no dwarfs from our sample can
be identified as 'field' objects.


title: A local optimal diastolic inequality on the two-sphere

abstract:
  Using a ramified cover of the two-sphere by the torus, we prove a local
optimal inequality between the diastole and the area on the two-sphere near a
singular metric. This singular metric, made of two equilateral triangles glued
along their boundary, has been conjectured by E. Calabi to achieve the best
ratio area over the square of the length of a shortest closed geodesic. Our
diastolic inequality asserts that this conjecture is to some extent locally
true.


title: Classical field theory. Advanced mathematical formulation

abstract:
  In contrast with QFT, classical field theory can be formulated in strict
mathematical terms of fibre bundles, graded manifolds and jet manifolds. Second
Noether theorems provide BRST extension of this classical field theory by means
of ghosts and antifields for the purpose of its quantization.


title: Moduli stabilization with F-term uplifting in heterotic string theory

abstract:
  We discuss the role of F-term uplifting in stabilizing moduli within the
framework of heterotic string theory. It turns out that the uplifting sector
plays an important role in fixing the volume modulus at one of the self-dual
points of a modular invariant potential. For the volume modulus stabilized at a
self-dual point, the F-term uplifting leads to the dilation stabilization which
can naturally yield the mirage mediation pattern of soft supersymmetry breaking
terms. Generalizing to the case with anomalous U(1) gauge symmetry, we also
find that the U(1) sector generically gives a contribution to sfermion masses
comparable to the dilaton mediated one while maintaining the mirage mediation
pattern.


title:
Visualization and analysis of jet oscillation under transverse acoustic
  perturbation

abstract:
  Schlieren flow visualizations of transverse oscillations of jets submitted to
an acoustic perturbation are analyzed in this paper. The aim is to estimate the
shape and the position of the median line of the jet. Two methods for image
processing are proposed, based on complementary approaches : inter image and
intra image analysis. Synthesized images of an oscillating jet are used to
validate each method and compare their performances in the case of noisy
pictures. Illustrations are then shown on real laminar and turbulent jets. The
results obtained using both methods are very close, showing their reliability.
Applications investigated in this paper are focused on the estimation of the
convection velocity of perturbations along the jet, and the influence of the
Reynolds number and of the channel geometry upstream the jet formation.


title:
Thermionic Emission, Multielectron Bubbles, and A Novel Electron
  Collector in a Liquid Helium Environment

abstract:
  We study two techniques to create electrons in a liquid helium environment.
One is thermionic emission of tungsten filaments in a low temperature cell in
the vapor phase with a superfluid helium film covering all surfaces; the other
is operating a glowing filament immersed in bulk liquid helium. We present both
the steady state and rapid sweep I-V curves and the electron current yield.
These curves, having a negative dynamic resistance region, differ remarkably
from those of a vacuum tube filament. A novel low temperature vapor-phase
electron collector for which the insulating helium film on the collector
surface can be removed is used to measure emission current. We also discuss our
achievement of producing multi-electron bubbles (MEBs) in liquid helium by a
new method.


title: Cooperative interface of a swarm of UAVs

abstract:
  After presenting the broad context of authority sharing, we outline how
introducing more natural interaction in the design of the ground operator
interface of UV systems should help in allowing a single operator to manage the
complexity of his/her task. Introducing new modalities is one one of the means
in the realization of our vision of next- generation GOI. A more fundamental
aspect resides in the interaction manager which should help balance the
workload of the operator between mission and interaction, notably by applying a
multi-strategy approach to generation and interpretation. We intend to apply
these principles to the context of the Smaart prototype, and in this
perspective, we illustrate how to characterize the workload associated with a
particular operational situation.


title:
A Pentagonal Crystal, the Golden Section, alcove packing and aperiodic
  tilings

abstract:
  A Lie theoretic interpretation is given to a pattern with five-fold symmetry
occurring in aperiodic Penrose tiling based on isosceles triangles with length
ratios equal to the Golden Section. Specifically a $B(\infty)$ crystal based on
that of Kashiwara is constructed exhibiting this five-fold symmetry. It is
shown that it can be represented as a Kashiwara $B(\infty)$ crystal in type
$A_4$. Similar crystals with $(2n+1)$-fold symmetry are represented as
Kashiwara crystals in type $A_{2n}$. The weight diagrams of the latter inspire
higher aperiodic tiling. In another approach alcove packing is seen to give
aperiodic tiling in type $A_4$. Finally $2m$-fold symmetry is related to type
$B_m$.


title: Potential Models for Quarkonia

abstract:
  n this paper I discuss what we can learn about quarkonium dissociation from
lattice-potential based models. Special emphasis is given to results obtained
in agreement by different models, and to the relevance of lattice QCD for
potential models. Future directions are also discussed.


title:
Pressure-induced quenching of the charge-density-wave state observed by
  x-ray diffraction

abstract:
  We report an x-ray diffraction study on the charge-density-wave (CDW)
LaTe$_3$ and CeTe$_3$ compounds as a function of pressure. We extract the
lattice constants and the CDW modulation wave-vector, and provide direct
evidence for a pressure-induced quenching of the CDW phase. We observe subtle
differences between the chemical and mechanical compression of the lattice. We
account for these with a scenario where the effective dimensionality in these
CDW systems is dependent on the type of lattice compression and has a direct
impact on the degree of Fermi surface nesting and on the strength of
fluctuation effects.


title: Designing lattice structures with maximal nearest-neighbor entanglement

abstract:
  In this work, we study the numerical optimization of nearest-neighbor
concurrence of bipartite one and two dimensional lattices, as well as non
bipartite two dimensional lattices. These systems are described in the
framework of a tight-binding Hamiltonian while the optimization of concurrence
was performed using genetic algorithms. Our results show that the concurrence
of the optimized lattice structures is considerably higher than that of non
optimized systems. In the case of one dimensional chains the concurrence is
maximized when the system begins to dimerize, i.e. it undergoes a structural
phase transition (Peierls distortion). This result is consistent with the idea
that entanglement is maximal or shows a singularity near quantum phase
transitions and that quantum entanglement cannot be freely shared between many
objects (monogamy property). Moreover, the optimization of concurrence in
two-dimensional bipartite and non bipartite lattices is achieved when the
structures break into smaller subsystems, which are arranged in geometrically
distinguishable configurations. This behavior is again related to the monogamy
property.


title:
Document stream clustering: experimenting an incremental algorithm and
  AR-based tools for highlighting dynamic trends

abstract:
  We address here two major challenges presented by dynamic data mining: 1) the
stability challenge: we have implemented a rigorous incremental density-based
clustering algorithm, independent from any initial conditions and ordering of
the data-vectors stream, 2) the cognitive challenge: we have implemented a
stringent selection process of association rules between clusters at time t-1
and time t for directly generating the main conclusions about the dynamics of a
data-stream. We illustrate these points with an application to a two years and
2600 documents scientific information database.


title: Searching For New Physics With B to K pi Decays

abstract:
  We propose a method to quantify the Standard Model uncertainty in B to K pi
decays using the experimental data, assuming that power counting provides a
reasonable estimate of the subleading terms in the 1/mb expansion. Using this
method, we show that present B to K pi data are compatible with the Standard
Model. We analyze the pattern of subleading terms required to reproduce the B
to K pi data and argue that anomalously large subleading terms are not needed.
Finally, we find that S(KS pi0) is fairly insensitive to hadronic uncertainties
and obtain the Standard Model estimate S(KS pi0)=0.74 +- 0.04.


title:
Pressure dependence of the single particle excitation in the
  charge-density-wave CeTe$_3$ system

abstract:
  We present new data on the pressure dependence at 300 K of the optical
reflectivity of CeTe$_3$, which undergoes a charge-density-wave (CDW) phase
transition well above room temperature. The collected data cover an
unprecedented broad spectral range from the infrared up to the ultraviolet,
which allows a robust determination of the gap as well as of the fraction of
the Fermi surface affected by the formation of the CDW condensate. Upon
compressing the lattice there is a progressive closing of the gap inducing a
transfer of spectral weight from the gap feature into the Drude component. At
frequencies above the CDW gap we also identify a power-law behavior, consistent
with findings along the $R$Te$_3$ series (i.e., chemical pressure) and
suggestive of a Tomonaga-Luttinger liquid scenario at high energy scales. This
newest set of data is placed in the context of our previous investigations of
this class of materials and allows us to revisit important concepts for the
physics of CDW state in layered-like two-dimensional systems.


title: Fractal Generalized Zone Plates

abstract:
  The construction of fractal generalized zone plates (FraGZPs) from a set of
periodic diffractive optical elements with circular symmetry is proposed. This
allows us to increase the number of foci of a conventional fractal zone plate
(FraZP), keeping the self-similarity property within the axial irradiance. The
focusing properties of these fractal diffractive optical elements for points
not only along but also in the close vicinity of the optical axis are
investigated. In both cases analytical expressions for the irradiance are
derived. Numerical simulations of the energetic efficiency of FraGZPs under
plane wave illumination are carried out. In addition, some effects on the axial
irradiance caused by the variation in area of their transparent rings are
shown.


title:
Measurement of W-Boson Helicity Fractions in Top-Quark Decays Using
  costheta*

abstract:
  Fully reconstructed top-antitop-events are used to determine the fractions of
right-handed and longitudinally polarized W bosons produced in top-quark
decays. The helicity fractions are sensitive to the couplings and the Dirac
structure of the Wtb vertex. This paper reports measurements of the W-boson
helicity fractions from two different methods using data corresponding to an
integrated luminosity of 1.9 fb-1 of proton-antiproton collisions collected by
the CDF II detector operating at the Fermilab Tevatron.


title: S4 as a natural flavor symmetry for lepton mixing

abstract:
  Group theoretical arguments seem to indicate the discrete symmetry S4 as the
minimal flavour symmetry compatible with tribimaximal neutrino mixing. We prove
in a model independent way that indeed S4 can realize exact tribimaximal mixing
through different symmetry breaking patterns. We present two models in which
lepton tribimaximal mixing is realized in different ways and for each one we
discuss the superpotential that leads to the correct breaking of the flavor
symmetry.


title:
Fisher-Hartwig conjecture and the correlators in the inpenetrable Bose
  gas

abstract:
  We apply the theorems from the theory of Toeplitz determinants to calculate
the asymptotics of various correlators including the exponential ones in the
inpenetrable one-dimensional Bose gas system. The known correlators in the
free-fermion system are also used to test the generalized Fisher-Hartwig
conjecture.

categories: math-ph cond-mat.stat-mech hep-th math.MP


title: Relations between organisms and the environment in the ageing process

abstract:
  We have modified the sexual Penna model by introducing the fluctuating
environment and fluctuations representing physiological functions of
individuals. Additionally, we have introduced the mother care corresponding to
the protection against the deleterious influence of the environment, the
learning capacity of individuals corresponding to their immunity and adaptation
to the environment fluctuations and the other risk factors appearing at
puberty. Each of the above mentioned elements influences mainly the survival of
newborns and young individuals while genetic defects accumulated in the genomes
increase the noise of individuals and were responsible for higher mortality of
older individuals. All these modifications enable precise fitting the age
structure of the simulated populations to the age distributions of human
populations.


title:
Doppler maps and surface differential rotation of EI Eri from the
  MUSICOS 1998 observations

abstract:
  We present time-series Doppler images of the rapidly-rotating active binary
star EI Eri from spectroscopic observations collected during the MUSICOS
multi-site campaign in 1998, since the critical rotation period of 1.947 days
makes it impossible to obtain time-resolved images from a single site. From the
surface reconstructions a weak solar-type differential rotation, as well as a
tiny poleward meridional flow are measured.


title: Schwinger Pair Production at Finite Temperature in QED

abstract:
  We use the evolution operator method to find the Schwinger pair-production
rate at finite temperature in scalar and spinor QED by counting the vacuum
production, the induced production and the stimulated annihilation from the
initial ensemble. It is shown that the pair-production rate for each state is
factorized into the mean number at zero temperature and the initial thermal
distribution for bosons and fermions.


title: Dispersion in magnetostatic CoTaZr spin wave-guides

abstract:
  Magnetostatic spin wave dispersion and loss are measured in micron scale spin
wave-guides in ferromagnetic, metallic CoTaZr. Results are in good agreement
with model calculations of spin wave dispersion and up to three different modes
are identified. Attenuation lengths of the order of 3 microns are several of
orders of magnitude shorter than that predicted from eddy currents in these
thin wires.


title:
Combinatorics of dispersionless integrable systems and universality in
  random matrix theory

abstract:
  It is well-known that the partition function of the unitary ensembles of
random matrices is given by a tau-function of the Toda lattice hierarchy and
those of the orthogonal and symplectic ensembles are tau-functions of the Pfaff
lattice hierarchy. In these cases the asymptotic expansions of the free
energies given by the logarithm of the partition functions lead to the
dispersionless (i.e. continuous) limits for the Toda and Pfaff lattice
hierarchies. There is a universality between all three ensembles of random
matrices, one consequence of which is that the leading orders of the free
energy for large matrices agree. In this paper, this universality, in the case
of Gaussian ensembles, is explicitly demonstrated by computing the leading
orders of the free energies in the expansions. We also show that the free
energy as the solution of the dispersionless Toda lattice hierarchy gives a
solution of the dispersionless Pfaff lattice hierarchy, which implies that this
universality holds in general for the leading orders of the unitary,
orthogonal, and symplectic ensembles.
  We also find an explicit formula for the two point function $F_{nm}$ which
represents the number of connected ribbon graphs with two vertices of degrees n
and m on a sphere. The derivation is based on the Faber polynomials defined on
the spectral curve of the dispersionless Toda lattice hierarchy, and
$\frac{1}{nm} F_{nm}$ are the Grunsky coefficients of the Faber polynomials.


title: Evolution of the personal income distribution in the USA: High incomes

abstract:
  The personal income distribution (PID) above the Pareto threshold is studied
and modeled. A microeconomic model is proposed to simulate the PID and its
evolution below and above the Pareto income threshold. The model balances
processes of income production and dissipation for any person above 15 years of
age. The model accurately predicts the observed dependence of the number of
people reaching the Pareto threshold on work experience and the functional
dependence of the relationship on the per capita real GDP growth for the period
from 1994 to 2002. Predictions of the income distribution depending on age are
given for past and future. In future, relatively less rich people are observed
in the younger age groups and the peak of the relative number shifts to older
ages with time. The effect of the power law distribution extending itself to
very high incomes is speculated to be the cause of low performance of socialist
countries.


title:
Dispersion and spin wave "tunneling" in nano-structured magnetostatic
  spin waveguides

abstract:
  Magnetostatic spin wave dispersion and loss are measured in micron scale spin
wave-guides in ferromagnetic, metallic CoTaZr. Results are in good agreement
with model calculations of spin wave dispersion. The measured attenuation
lengths, of the order of 3um, are several of orders of magnitude shorter than
that predicted from eddy currents in these thin wires. Spin waves effectively
"tunnel" through air gaps, produced by focused ion beam etching, as large as
1.5 um.


title: Lectures on black holes and linear waves

abstract:
  These lecture notes, based on a course given at the Zurich Clay Summer School
(June 23-July 18, 2008), review our current mathematical understanding of the
global behaviour of waves on black hole exterior backgrounds. Interest in this
problem stems from its relationship to the non-linear stability of the black
hole spacetimes themselves as solutions to the Einstein equations, one of the
central open problems of general relativity. After an introductory discussion
of the Schwarzschild geometry and the black hole concept, the classical theorem
of Kay and Wald on the boundedness of scalar waves on the exterior region of
Schwarzschild is reviewed. The original proof is presented, followed by a new
more robust proof of a stronger boundedness statement. The problem of decay of
scalar waves on Schwarzschild is then addressed, and a theorem proving
quantitative decay is stated and its proof sketched. This decay statement is
carefully contrasted with the type of statements derived heuristically in the
physics literature for the asymptotic tails of individual spherical harmonics.
Following this, our recent proof of the boundedness of solutions to the wave
equation on axisymmetric stationary backgrounds (including slowly-rotating Kerr
and Kerr-Newman) is reviewed and a new decay result for slowly-rotating Kerr
spacetimes is stated and proved. This last result was announced at the summer
school and appears in print here for the first time. A discussion of the
analogue of these problems for spacetimes with a positive cosmological constant
follows. Finally, a general framework is given for capturing the red-shift
effect for non-extremal black holes. This unifies and extends some of the
analysis of the previous sections. The notes end with a collection of open
problems.


title:
Quark mixing renormalization effects in the determination of the CKM
  parameters |V_{ij}|

abstract:
  We briefly review existing proposals for the renormalization of the
Cabibbo-Kobayashi-Maskawa (CKM) matrix and study the numerical effects of
several of them on the W-boson hadronic partial decay widths. We then use these
results to evaluate the relative shifts on the CKM parameters |V_{ij}|^2
induced by the quark mixing renormalization effects, as well as their scheme
dependence. We also discuss the implications of this analysis for the most
precise unitarity test of the CKM matrix.


title:
Modeling the evolution of Gini coefficient for personal incomes in the
  USA between 1947 and 2005

abstract:
  The evolution of Gini coefficient for personal incomes in the USA between
1947 and 2005 is analyzed and modeled. There are several versions of personal
income distribution (PID) provided by the US Census Bureau (US CB) for this
period with various levels of resolution. Effectively, these PIDs result in
different Gini coefficients due to the differences between discrete and
continuous representations. When all persons of 15 years of age and over are
included in the PIDs, Gini coefficient drops from 0.64 in 1947 to 0.54 in 1990.
This effect is observed due to a significant decrease in the portion of people
without income. For the PIDs not including persons without income, Gini
coefficient is varying around 0.51 between 1960 and 2005 with standard
deviation of 0.004, i.e. is in fact constant. This Gini coefficient is
practically independent on the portion of population included in the PIDs
according to any revision of income definitions. The driving force of the model
describing the evolution of individual incomes (microeconomic level) and their
aggregate value (macroeconomic level) is the change in nominal GDP per capita.
The model accurately predicts the evolution of Gini coefficient for the PIDs
for people with income. The model gives practically unchanged (normalized) PIDs
and Gini coefficient between 1947 and 2005. The empirical Gini curves converge
to the predicted one when the number of people without income decreases.
Asymptotically, the empirical curves should collapse to the theoretical one
when all the working age population obtains an appropriate definition of
income. Therefore the model Gini coefficient potentially better describes true
behavior of inequality in the USA because the definitions of income used by the
US Census Bureau apparently fail to describe true income distribution.


title:
The Pseudo Radiation Energy Amplifier (PREA) and the mean earth s ground
  temperature

abstract:
  From the radiation balance diagram illustrating the IPCC reports one can
estimate the power received by Earth from the sun at Pin = 342 W/m2 and the
power consumed, remitted and reflected by the earth and its atmosphere at Pout
= 599 kW/m2. It seems that the earth emits more power than it receives. The
earth s ground mean temperature is estimated at 15 C. A calculation based on
the black body radiation theory gives an earth s ground mean temperature of the
order of -18 C which is much lower than 15 C. The important gap between these
calculated and estimated temperature mean values requires an explanation. Here
we show that a gray body separated from vacuum by an interface and submitted to
outside incident radiation can behave like a Pseudo Radiation Energy Amplifier.
The Earth which is a gray body separated from the space by an interface,
behaves like a Pseudo Radiation Energy Amplifier. The balance of the energy
exchanged between Earth and outer space is reconsidered and the 15 C Earth s
ground temperature mean value is then derived. Our result revives the
discussion on the parameters that control the Earth climate. The solar and
terrestrial radiation reflection coefficients by the earth and its atmosphere
acquire a privileged role. The Pseudo Radiation Energy Amplifier can be a
starting point to improve the energy use. The materials having the adequate
reflection coefficients will be indicated for specific applications.


title: Lower bounds for the principal genus of definite binary quadratic forms

abstract:
  We apply Tatuzawa's version of Siegel's theorem to derive two lower bounds on
the size of the principal genus of positive definite binary quadratic forms.


title:
Embedding Non-Ground Logic Programs into Autoepistemic Logic for
  Knowledge Base Combination

abstract:
  In the context of the Semantic Web, several approaches to the combination of
ontologies, given in terms of theories of classical first-order logic and rule
bases, have been proposed. They either cast rules into classical logic or limit
the interaction between rules and ontologies. Autoepistemic logic (AEL) is an
attractive formalism which allows to overcome these limitations, by serving as
a uniform host language to embed ontologies and nonmonotonic logic programs
into it. For the latter, so far only the propositional setting has been
considered. In this paper, we present three embeddings of normal and three
embeddings of disjunctive non-ground logic programs under the stable model
semantics into first-order AEL. While the embeddings all correspond with
respect to objective ground atoms, differences arise when considering
non-atomic formulas and combinations with first-order theories. We compare the
embeddings with respect to stable expansions and autoepistemic consequences,
considering the embeddings by themselves, as well as combinations with
classical theories. Our results reveal differences and correspondences of the
embeddings and provide useful guidance in the choice of a particular embedding
for knowledge combination.


title:
Generalization of the Logarithm Function and of the Exponential Function
  with Arbitrary Base

abstract:
  The logarithm function and the exponential function are, by nature, base
dependent. Thus, in this paper I introduces an arbitrary base in the logarithm
and exponential functions, both dependent on $q$, in order to have
$\log_a(x;q)$ and $a_q^x$. Some of the properties of these functions had been
analyzed. The logarithm function was applied to the entropy which resulted in
the $S_q = k[1 - \sum_{i = 1}^Wp_i^{q}]/[1 - e^{1 - q}]$ expression.


title:
Different superconducting percolation regimes in the layered organic
  Mott system $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Cl -- evidence from
  fluctuation spectroscopy

abstract:
  Fluctuation spectroscopy is used to investigate the organic
bandwidth-controlled Mott system $\kappa$-(BEDT-TTF)$_2$Cu[N(CN)$_2$]Cl. We
find evidence for percolative-type superconductivity in the spatially
inhomogeneous coexistence region of antiferromagnetic insulating and
superconducting states which develops under pressure at low temperatures. When
the superconducting transition is driven by a magnetic field, percolation seems
to be dominated by unstable superconducting clusters upon approaching $T_c (B)$
from above, before a "classical" type of percolation is resumed at low fields,
dominated by the fractional change of superconducting clusters. The $1/f$ noise
is resolved into Lorentzian spectra in the crossover region where the action of
an individual mesoscopic fluctuator is enhanced.


title: Colliding Waves on a Brane, the Big Bounce and Reconnection

abstract:
  We present a time-dependent solution of the Nambu-Goto action which
represents two colliding waves moving at the speed of light. This solution can
be decomposed into two distinct regions with different geometries corresponding
to shrinking or expanding brane universe and two colliding branes. The former
describes the Big Bounce without singularity while the latter describes that
two branes collide and reconnect to each other. The colliding brane region has
a signature change. Classical dynamics of a massive particle on the brane is
studied through the geodesics.


title:
Observations of V592 Cassiopeiae with the Spitzer Space Telescope - Dust
  in the Mid-Infrared

abstract:
  We present the ultraviolet-optical-infrared spectral energy distribution of
the low inclination novalike cataclysmic variable V592 Cassiopeiae, including
new mid-infrared observations from 3.5-24 microns obtained with the Spitzer
Space Telescope. At wavelengths shortward of 8 microns, the spectral energy
distribution of V592 Cas is dominated by the steady state accretion disk, but
there is flux density in excess of the summed stellar components and accretion
disk at longer wavelengths. Reproducing the observed spectral energy
distribution from ultraviolet to mid-infrared wavelengths can be accomplished
by including a circumbinary disk composed of cool dust, with a maximum inner
edge temperature of ~500 K. The total mass of circumbinary dust in V592 Cas
(~10^21 g) is similar to that found from recent studies of infrared excess in
magnetic CVs, and is too small to have a significant effect on the long-term
secular evolution of the cataclysmic variable. The existence of circumbinary
dust in V592 Cas is possibly linked to the presence of a wind outflow in this
system, which can provide the necessary raw materials to replenish the
circumbinary disk on relatively short timescales, and/or could be a remnant
from the common envelope phase early in the formation history of the system.


title: Extending Isotopies of Planar Continua

abstract:
  In this paper we solve the following problem in the affirmative: Let $Z$ be a
continuum in the plane $\complex$ and suppose that $h:Z\times [0,1]\to\complex$
is an isotopy starting at the identity. Can $h$ be extended to an isotopy of
the plane?
  We will provide a new characterization of an accessible point in a planar
continuum $Z$ and use it to show that an accessible point is preserved during
the isotopy. We show next that the isotopy can be extended over hyperbolic
crosscuts. The proof makes use of the notion of a metric external ray, which
mimics the notion of a conformal external ray, but is easier to control during
an isotopy.


title:
$J$-self-adjoint operators with $\mathcal{C}$-symmetries: extension
  theory approach

abstract:
  A well known tool in conventional (von Neumann) quantum mechanics is the
self-adjoint extension technique for symmetric operators. It is used, e.g., for
the construction of Dirac-Hermitian Hamiltonians with point-interaction
potentials. Here we reshape this technique to allow for the construction of
pseudo-Hermitian ($J$-self-adjoint) Hamiltonians with complex
point-interactions. We demonstrate that the resulting Hamiltonians are
bijectively related with so called hypermaximal neutral subspaces of the defect
Krein space of the symmetric operator. This symmetric operator is allowed to
have arbitrary but equal deficiency indices $<n,n>$. General properties of the
$\cC$ operators for these Hamiltonians are derived. A detailed study of
$\cC$-operator parametrizations and Krein type resolvent formulas is provided
for $J$-self-adjoint extensions of symmetric operators with deficiency indices
$<2,2>$. The technique is exemplified on 1D pseudo-Hermitian Schr\"odinger and
Dirac Hamiltonians with complex point-interaction potentials.


title:
Quenched invariance principle for the Knudsen stochastic billiard in a
  random tube

abstract:
  We consider a stochastic billiard in a random tube which stretches to
infinity in the direction of the first coordinate. This random tube is
stationary and ergodic, and also it is supposed to be in some sense well
behaved. The stochastic billiard can be described as follows: when strictly
inside the tube, the particle moves straight with constant speed. Upon hitting
the boundary, it is reflected randomly, according to the cosine law: the
density of the outgoing direction is proportional to the cosine of the angle
between this direction and the normal vector. We also consider the
discrete-time random walk formed by the particle's positions at the moments of
hitting the boundary. Under the condition of existence of the second moment of
the projected jump length with respect to the stationary measure for the
environment seen from the particle, we prove the quenched invariance principles
for the projected trajectories of the random walk and the stochastic billiard.


title: Black holes and balanced metrics

abstract:
  We consider a probe in a BPS black hole in type II strings compactified on
Calabi-Yau manifolds, and conjecture that its moduli space metric is the
balanced metric.


title: Tracking fast small color dipoles through strong gluon fields at the LHC

abstract:
  We argue that the process gamma +A \to J/psi + gap + X at large momentum
transfer provides a quick and effective way to test onset of a novel
perturbative QCD regime of strong absorption for the interaction of small
dipoles at the collider energies. We find that already the first heavy ion run
at the LHC will allow to study this reaction with sufficient statistics via
ultraperipheral collisions hence probing the interaction of q\bar q dipoles of
sizes ~ 0.2 fm with nuclear media down to x ~ 10^{-5}.


title:
Search for Charged Current Coherent Pion Production on Carbon in a
  Few-GeV Neutrino Beam

abstract:
  The SciBooNE Collaboration has performed a search for charged current
coherent pion production from muon neutrinos scattering on carbon, \nu_\mu
^{12}C \to \mu^- ^{12}C \pi^+, with two distinct data samples. No evidence for
coherent pion production is observed. We set 90% confidence level upper limits
on the cross section ratio of charged current coherent pion production to the
total charged current cross section at 0.67\times 10^{-2} at mean neutrino
energy 1.1 GeV and 1.36\times 10^{-2} at mean neutrino energy 2.2 GeV.


title: Remarks on Springer's representations

abstract:
  We give an apriori description of a set of irreducible representations of a
Weyl group which parametrize the nilpotent orbits in the Lie algebra of a
connected reductive group in arbitrary characteristic. We also answer a
question of Serre concerning the conjugacy class of a power of a unipotent
element in a connected reductive group.


title:
Gaseous drag on a gravitational perturber in Modified Newtonian Dynamics
  and the structure of the wake

abstract:
  We calculate the structure of a wake generated by, and the dynamical friction
force on, a gravitational perturber travelling through a gaseous medium of
uniform density and constant background acceleration g_ext, in the context of
Modified Newtonian Dynamics (MOND). The wake is described as a linear
superposition of two terms. The dominant part displays the same structure as
the wake generated in Newtonian gravity scaled up by a factor
mu^{-1}(g_ext/a_0), where a_{0} is the constant MOND acceleration and mu the
interpolating function. The structure of the second term depends greatly on the
angle between g_{ext} and and the velocity of the perturber. We evaluate the
dynamical drag force numerically and compare our MOND results with the
Newtonian case. We mention the relevance of our calculations to orbit evolution
of globular clusters and satellites in a gaseous proto-galaxy. Potential
differences in the X-ray emission of gravitational galactic wakes in MOND and
in Newtonian gravity with a dark halo are highlighted.


title: Sharp Transitions in Making Squares

abstract:
  In many integer factoring algorithms, one produces a sequence of integers
(created in a pseudo-random way), and wishes to rapidly determine a subsequence
whose product is a square (which we call a square product). In his lecture at
the 1994 International Congress of Mathematicians, Pomerance observed that the
following problem encapsulates all of the key issues: Select integers a_1, a_2,
>... at random from the interval [1,x], until some (non-empty) subsequence has
product equal to a square. Find good estimate for the expected stopping time of
this process. A good solution to this problem should help one to determine the
optimal choice of parameters for one's factoring algorithm, and therefore this
is a central question.
  Pomerance (1994), using an idea of Schroeppel (1985), showed that with
probability 1-o(1) the first subsequence whose product equals a square occurs
after at least J_0^{1-o(1)} integers have been selected, but no more than J_0,
for an appropriate (explicitly determined) J_0=J_0(x). Herein we determine this
expected stopping time up to a constant factor, tightening Pomerance's interval
to $$[ (\pi/4)(e^{-\gamma} - o(1))J_0, (e^{-\gamma} + o(1)) J_0],$$ where
$\gamma = 0.577...$ is the Euler-Mascheroni constant. We will also confirm the
well established belief that, typically, none of the integers in the square
product have large prime factors. We believe the upper of the two bounds to be
asymptotically sharp.


title:
Dipole emission and coherent transport in random media II. Density of
  states vs. index of refraction

abstract:
  This is the second of a series of papers devoted to develop a microscopical
approach to the dipole emission process and its relation to coherent transport
in random media. In this Letter, we deduce a relation between the transverse
decay rate of an emitter in a virtual cavity and the complex refraction index
of the host medium. We argue on the possibility of a criterion for
inhibition/enhancement of spontaneous emission in function of the transition
frequency and the correlation length of the host scatterers. In addition, we
study the radiative/non-radiative nature of the net power emission through a
microscopical analysis of the scattering events involved. This study reveals
essential discrepancies with previous interpretations.

categories: physics.optics cond-mat.dis-nn cond-mat.mes-hall physics.chem-ph


title: Evidence of natural isotopic distribution from single-molecule SERS

abstract:
  We report on the observation of the natural isotopic spread of carbon from
single-molecule Surface Enhanced Raman Spectroscopy (SM-SERS). By choosing a
dye molecule with a very localized Raman active vibration in a cyano bond
(C$\equiv$N triple bond), we observe (in a SERS colloidal liquid) a small
fraction of SM-SERS events where the frequency of the cyano mode is softened
and in agreement with the effect of substituting $^{12}$C by the next most
abundant $^{13}$C isotope. This example adds another demonstration of single
molecule sensitivity in SERS through isotopic editing which is done, in this
case, not by artificial isotopic editing but rather by nature itself. It also
highlights SERS as a unique spectroscopic tool, capable of detecting an
isotopic change in one atom of a single molecule.


title: Implications of cosmic ray results for UHE neutrinos

abstract:
  Recent measurements of the spectrum and composition of ultrahigh energy
cosmic rays suggest that their extragalactic sources may be accelerating heavy
nuclei in addition to protons. This can suppress the cosmogenic neutrino flux
relative to the usual expectation for an all-proton composition. Cosmic
neutrino detectors may therefore need to be even larger than currently planned
but conversely they will also be able to provide valuable information
concerning astrophysical accelerators. Moreover measurement of ultrahigh energy
cosmic neutrino interactions can provide an unique probe of QCD dynamics at
high parton density.


title: Exact prediction of S&P 500 returns

abstract:
  A linear link between S&P 500 return and the change rate of the number of
nine-year-olds in the USA has been found. The return is represented by a sum of
monthly returns during previous twelve months. The change rate of the specific
age population is represented by moving averages. The period between January
1990 and December 2003 is described by monthly population intercensal estimates
as provided by the US Census Bureau. Four years before 1990 are described using
the estimates of the number of 17 year-olds shifted 8 years back. The
prediction of S&P 500 returns for the months after 2003, including those beyond
2007, are obtained using the number of 3 year-olds between 1990 and 2003
shifted by 6 years ahead and quarterly estimates of real GDP per capita. A
prediction is available for the period beyond 2007. There are two sharp drops
in the predicted returns - in 2007 and 2009, and one strong rally in 2008.
Equivalently, S&P 500 index should drop in 2007 and 2009 to the level observed
one year before. Potential link between S&P 500 returns and 9-year-old
population is tested for cointegration. The Engle-Granger and Johansen tests
demonstrate the presence of a long-term equilibrium (cointegrating) relation
between these variables. This makes valid standard statistical estimates.
Correlation between the predicted and observed indices, including RMS
difference, linear regression, and VAR demonstrate good prediction accuracy at
two-year horizon, when the prediction uses 7-year-olds instead of 9-year-olds.
The RMS difference between the observed and predicted returns for the period
between 1992 and 2003 is only 0.09 with standard deviation of the observed
series for the same period of 0.12 and the naive (random walk) RMS deference of
0.18.


title: Analytical Solutions to the Navier-Stokes Equations

abstract:
  With the previous results for the analytical blowup solutions of the
N-dimensional Euler-Poisson equations, we extend the similar structure to
construct an analytical family of solutions for the isothermal Navier-Stokes
equations and pressureless Navier-Stokes equations with density-dependent
viscosity.


title: Quantal Definition of the Weak Equivalence Principle

abstract:
  The present work analyzes the meaning of the Weak Equivalence Principle in
the context of quantum mechanics. A quantal definition for this principle is
introduced. This definition does not require the concept of trajectory and
relies upon the phase shift induced by a gravitational field in the context of
a quantum interference experiment of two coherent beams of particles. In other
words, it resorts to wave properties of the system and not to classical
concepts as the idea of trajectory.


title:
Analytical Blowup Solutions to the 3-dimensional Pressureless
  Navier-Stokes-Poisson Equations with Density-dependent Viscosity

abstract:
  We study the pressureless Navier--Stokes-Poisson equations of describing the
evolution of the gaseous star in astrophysics. The isothermal blowup solutions
of Yuen, to the Euler-Poisson equations in R2, can be extended to the
pressureless Navier-Stokes-Poisson equations with density-dependent viscosity
in R3. Besides some remarks, about the meaning of the blowup solutions and the
applicability of such solutions to the the drift-diffusion model in
semiconductors, are discussed in the end.


title:
Ab initio calculation of structural and electronic properties of
  Al$_x$Ga$_{1-x}$N and In$_x$Ga$_{1-x}$N alloys

abstract:
  Using the density functional theory (DFT) with the generalized gradient
approximation (GGA), the structural and electronic properties of wurtzite AlN,
GaN, InN, and their related alloys, Al$_x$Ga$_{1-x}$N and In$_x$Ga$_{1-x}$N,
were calculated. We have performed accurate {\it ab initio} total energy
calculations using the full--potential linearized augmented plane wave
(FP--LAPW) method to investigate the structural and electronic properties. In
both alloys we found that the fundamental parameters do not follow Vegard's
law. The lattice parameters, $a, c,$ and $u$, for the Al$_x$Ga$_{1-x}$N alloy
are found to exhibit downward bowing, while for In$_x$Ga$_{1-x}$N there is an
upward bowing for the $a$ and $c$ parameters and a downward bowing for the
internal parameter, $u$. Furthermore, we found that for both alloys, the band
gap value does not follow Vegard's law. As a by--product of our electronic band
structure calculations, the effective masses of the binary compounds as well as
their related alloys were calculated. We show that the calculated properties
for the binary compounds, as well as for the studied alloys, show good
agreement with most of the previously reported results. Finally, using the
frozen phonon approach, the A$_1(TO)$ mode for the different systems studied in
this work was calculated. Our calculations show good agreement with
experimental values reported for the binary compounds. For the ternary alloys,
our calculations reproduce experimental values for Al$_x$Ga$_{1-x}$N as well as
theoretical predictions for In$_x$Ga$_{1-x}$N.


title:
On the dynamics of Social Balance on general networks (with an
  application to XOR-SAT)

abstract:
  We study nondeterministic and probabilistic versions of a discrete dynamical
system (due to T. Antal, P. L. Krapivsky, and S. Redner) inspired by Heider's
social balance theory. We investigate the convergence time of this dynamics on
several classes of graphs. Our contributions include:
  1. We point out the connection between the triad dynamics and a
generalization of annihilating walks to hypergraphs. In particular, this
connection allows us to completely characterize the recurrent states in graphs
where each edge belongs to at most two triangles.
  2. We also solve the case of hypergraphs that do not contain edges consisting
of one or two vertices.
  3. We show that on the so-called "triadic cycle" graph, the convergence time
is linear.
  4. We obtain a cubic upper bound on the convergence time on 2-regular triadic
simplexes G. This bound can be further improved to a quantity that depends on
the Cheeger constant of G. In particular this provides some rigorous
counterparts to previous experimental observations.
  We also point out an application to the analysis of the random walk algorithm
on certain instances of the 3-XOR-SAT problem.


title:
Halo Density Profiles Consistent with Asymmetric M-B Velocity
  Distributions-Implications on Direct Dark Matter Searches

abstract:
  In the present paper we obtain the WIMP velocity distribution in our vicinity
starting from spherically symmetric WIMP density profiles in a self consistent
way by employing the Eddington approach. By adding a reasonable angular
momentum dependent term in the expression of the energy, we obtain axially
symmetric WIMP velocity distributions as well. We find that some density
profiles lead to approximate Maxwell-Boltzmann distributions, which are
automatically defined in a finite domain, i.e. the escape velocity need not be
put by hand. The role of such distributions in obtaining the direct WIMP
detection rates, including the modulation, is studied in some detail and, in
particular, the role of the asymmetry is explored.


title:
Exact and Asymptotic Conditions on Traveling Wave Solutions of the
  Navier-Stokes Equations

abstract:
  We derive necessary conditions that traveling wave solutions of the
Navier-Stokes equations must satisfy in the pipe, Couette, and channel flow
geometries. Some conditions are exact and must hold for any traveling wave
solution irrespective of the Reynolds number ($Re$). Other conditions are
asymptotic in the limit $Re\to\infty$. The exact conditions are likely to be
useful tools in the study of transitional structures. For the pipe flow
geometry, we give computations up to $Re=100000$ showing the connection of our
asymptotic conditions to critical layers that accompany vortex structures at
high $Re$.

categories: physics.flu-dyn math.AP nlin.CD physics.ao-ph


title:
Critical thickness for itinerant ferromagnetism in ultrathin films of
  SrRuO$_3$

abstract:
  Ultrathin films of the itinerant ferromagnet SrRuO$_3$ were studied using
transport and magnto-optic polar Kerr effect. We find that below 4 monolayers
the films become insulating and their magnetic character changes as they loose
their simple ferromagnetic behavior. We observe a strong reduction in the
magnetic moment which for 3 monolayers and below lies in the plane of the film.
Exchange-bias behavior is observed below the critical thickness, and may point
to induced antiferromagnetism in contact with ferromagnetic regions.


title:
Compensation-dependent in-plane magnetization reversal processes in
  Ga1-xMnxP1-ySy

abstract:
  We report the effect of dilute alloying of the anion sublattice with S on the
in-plane uniaxial magnetic anisotropy and magnetization reversal process in
Ga1-xMnxP as measured by both ferromagnetic resonance (FMR) and superconducting
quantum interference device (SQUID) magnetometry. At T=5K, raising the S
concentration increases the uniaxial magnetic anisotropy between in-plane <011>
directions while decreasing the magnitude of the (negative) cubic anisotropy
field. Simulation of the SQUID magnetometry indicates that the energy required
for the nucleation and growth of domain walls decreases with increasing y.
These combined effects have a marked influence on the shape of the
field-dependent magnetization curves; while the direction remains the easy axis
in the plane of the film, the field dependence of the magnetization develops
double hysteresis loops in the [011] direction as the S concentration increases
similar to those observed for perpendicular magnetization reversal in lightly
doped Ga1-xMnxAs. The incidence of double hysteresis loops is explained with a
simple model whereby magnetization reversal occurs by a combination of coherent
spin rotation and noncoherent spin switching, which is consistent with both FMR
and magnetometry experiments. The evolution of magnetic properties with S
concentration is attributed to compensation of Mn acceptors by S donors, which
results in a lowering of the concentration of holes that mediate
ferromagnetism.


title:
\muSR-dtected Soft mode toward a Possible Phase Transition in disordered
  spin gap system (CH3)2CHNH3-Cu(ClxBr1-x)3

abstract:
  Measurements of macroscopic properties have indicated that the
bond-disordered spin-gap system (CH3)2CHNH3-Cu(ClxBr1-x)3 is gapless when x is
between 0.44 and 0.87. Using muon spin relaxation to investigate microscopic
properties of sample with x=0.35, we observed a dynamical spin fluctuation,
whose characteristic frequency decreases with decreasing temperature,
indicating a magnetic ground state.


title: A Unified Dark Matter Model in sUED

abstract:
  We propose a dark matter model with standard model singlet extension of the
universal extra dimension model (sUED) to explain the recent observations of
ATIC, PPB-BETS, PAMELA and DAMA. Other than the standard model fields
propagating in the bulk of a 5-dimensional space, one fermion field and one
scalar field are introduced and both are standard model singlets. The zero mode
of the new fermion is identified as the right-handed neutrino, while its first
KK mode is the lightest KK-odd particle and the dark matter candidate. The
cosmic ray spectra from ATIC and PPB-BETS determine the dark matter particle
mass and hence the fifth dimension compactification scale to be 1.0-1.6 TeV.
The zero mode of the singlet scalar field with a mass below 1 GeV provides an
attractive force between dark matter particles, which allows a Sommerfeld
enhancement to boost the annihilation cross section in the Galactic halo to
explain the PAMELA data. The DAMA annual modulation results are explained by
coupling the same scalar field to the electron via a higher-dimensional
operator. We analyze the model parameter space that can satisfy the dark matter
relic abundance and accommodate all the dark matter detection experiments. We
also consider constraints from the diffuse extragalactic gamma-ray background,
which can be satisfied if the dark matter particle and the first KK-mode of the
scalar field have highly degenerate masses.


title:
Renormalized phi^6 model for quantum phase transitions in systems of
  itinerant fermions

abstract:
  We study the impact of quantum and thermal fluctuations on properties of
quantum phase transitions occurring in systems of itinerant fermions with main
focus on the order of these transitions. Our approach is based on a set of flow
equations derived within the functional renormalization group framework, in
which the order parameter is retained as the only degree of freedom, and where
the effective potential is parametrized with a phi^6 form allowing for both
first and second order scenarios. We find a tendency to turn the first order
transitions within the bare model into second order transitions upon accounting
for the order parameter fluctuations. We compute the first and second order
phase boundary lines T_c as a function of a non-thermal control parameter a_2
in the vicinity of a quantum phase transition. We analyze crossovers of the
shift exponent psi governing the shape of the T_c line when the system is tuned
close to a quantum tricritical scenario, where a second order phase transition
line terminates at a quantum tricritical point.


title: SQUID-based microtesla MRI for in vivo relaxometry of the human brain

abstract:
  SQUID-based MRI (magnetic resonance imaging) at microtesla fields has
developed significantly over the past few years. Here we describe application
of this method for magnetic relaxation measurements in the living human brain.
We report values of the longitudinal relaxation time T1 for brain tissues,
measured in vivo for the first time at microtesla fields. The experiments were
performed at 46 microtesla field using a seven-channel SQUID system designed
for microtesla MRI and MEG. Values of T1, measured for different tissues at
this field, are found to be close (within 5%) to the corresponding values of
the transverse relaxation time T2 at the same field. Implications of this
result for imaging contrast in microtesla MRI are discussed.


title: On surfaces with p_g=2q-3

abstract:
  We study minimal complex surfaces S of general type with q(S)=q and
p_g(S)=2q-3, q>= 5. We give a complete classification in case that S has a
fibration onto a curve of genus >=2. For these surfaces K^2=8\chi. In general
we prove that K^2>=7\chi-1 and that the stronger inequality K^2\ge 8\chi holds
under extra assumptions (e.g., if the canonical system has no fixed part or the
canonical map has even degree).
  We also describe the Albanese map of S.


title: Color Bimodality in M87 Globular Clusters

abstract:
  We present an analysis of a 50 orbit HST ACS observation of the M87 globular
cluster system. We use the extraordinary depth of this dataset to test whether
the colors and magnitudes show evidence for a mass-metallicity relation in
globular cluster populations. We find only a weak or absent relation between
the colors and magnitudes of the metal poor subpopulation of globular clusters.
The weakness or absence of a color-magnitude relation is established over a
wide range in luminosity from $M_V=-11$ to $M_V=-6$, encompassing most of the
M87 globular clusters. The constancy of the colors of the metal-poor
subpopulation seen in our 50 orbit observation is in contrast to suggestions
from single orbit ACS data that the metal-poor globular clusters in M87 and
several other galaxies show a "blue tilt." The formal best fit for the
mass-metallicity relation for the metal-poor subpopulation in our much deeper
data is $Z\propto M^{0.08\pm0.05}$. Our analysis of these data also shows a
possible small "red tilt" in the metal-rich globular cluster subpopulation.
While either of these small tilts may be real, they may also illustrate the
limit to which mass-metallicity relations can be determined, even in such
extraordinarily deep data. We specifically test for a wide range of systematic
effects and find that while small tilts cannot be confirmed or rejected, the
data place a strong upper limit to any tilt of $|0.20|\pm0.05$. This upper
limit is much smaller than some earlier claims from single orbit data, and
strongly limits self-enrichment within globular clusters. This mass-metallicity
relation for globular clusters is also shallower than the relation for
galaxies, suggesting that the formation mechanisms for these two types of
objects are different.


title:
Detecting Mass Substructure in Galaxy Clusters: An Aperture Mass
  Statistic for Gravitational Flexion

abstract:
  Gravitational flexion has recently been introduced as a technique by which
one can map out and study substructure in clusters of galaxies. Previous
analyses involving flexion have measured the individual galaxy-galaxy flexion
signal, or used either parametric techniques or a KSB-type inversion to
reconstruct the mass distribution in Abell 1689. In this paper, we present an
aperture mass statistic for flexion, and apply it to the lensed images of
background galaxies obtained by ray-tracing simulations through a simple
analytic mass distribution and through a galaxy cluster from the Millennium
simulation. We show that this method is effective at detecting and accurately
tracing structure within clusters of galaxies on sub-arcminute scales with high
signal-to-noise even using a moderate background source number density and
image resolution. In addition, the method provides much more information about
both the overall shape and the small-scale structure of a cluster of galaxies
than can be achieved through a weak lensing mass reconstruction using
gravitational shear data. Lastly, we discuss how the zero-points of the
aperture mass might be used to infer the masses of structures identified using
this method.


title: Complex Singlet Extension of the Standard Model

abstract:
  We analyze a simple extension of the Standard Model (SM) obtained by adding a
complex singlet to the scalar sector (cxSM). We show that the cxSM can contain
one or two viable cold dark matter candidates and analyze the conditions on the
parameters of the scalar potential that yield the observed relic density. When
the cxSM potential contains a global U(1) symmetry that is both softly and
spontaneously broken, it contains both a viable dark matter candidate and the
ingredients necessary for a strong first order electroweak phase transition as
needed for electroweak baryogenesis. We also study the implications of the
model for discovery of a Higgs boson at the Large Hadron Collider.


title: A Composite Twin Higgs Model

abstract:
  Twin Higgs models are economical extensions of the Standard Model that
stabilize the electroweak scale. In these theories the Higgs field is a pseudo
Nambu-Goldstone boson that is protected against radiative corrections up to
scales of order 5 TeV by a discrete parity symmetry. We construct, for the
first time, a class of composite twin Higgs models based on confining QCD-like
dynamics. These theories naturally incoporate a custodial isospin symmetry and
predict a rich spectrum of particles with masses of order a TeV that will be
accessible at the LHC.


title: Anharmonic Ground state selection in the pyrochlore antiferromagnet

abstract:
  In the pyrochlore lattice Heisenberg antiferromagnet, for large spin length
$S$, the massive classical ground state degeneracy is partly lifted by the
zero-point energy of quantum fluctuations at harmonic order in spin-waves.
However, there remains an infinite manifold of degenerate collinear ground
states, related by a gaugelike symmetry. We have extended the spin-wave
calculation to quartic order, assuming a Gaussian variational wavefunction
(equivalent to Hartree-Fock approximation). Quartic calculations \emph{do}
break the harmonic-order degeneracy of periodic ground states. The form of the
effective Hamiltonian describing this splitting, which depends on loops, was
fitted numerically and also rationalized analytically. We find a family of
states that are still almost degenerate, being split by the term from loops of
length 26. We also calculated the anharmonic terms for the checkerboard
lattice, and discuss why it (as well as the kagom\'e lattice) behave
differently than the pyrochlore at anharmonic orders.


title: The Spectral Shape and Photon Fraction as Signatures of the GZK-Cutoff

abstract:
  With the prospect of measuring the fraction of arriving secondary photons,
produced through photo-pion energy loss interactions of ultra high energy
cosmic ray (UHECR) protons with the microwave background during propagation, we
investigate how information about the local UHECR source distribution can be
inferred from the primary (proton) to secondary (photon) ratio. As an aid to
achieve this, we develop an analytic description for both particle populations
as a function of propagation time. Through a consideration of the shape of the
GZK cut-off and the corresponding photon fraction curve, we investigate the
different results expected for both different maximum proton energies injected
by the sources, as well as a change in the local source distribution following
a perturbative deformation away from a homogeneous description. At the end of
the paper, consideration is made as to how these results are modified through
extra-galactic magnetic field effects on proton propagation. The paper aims to
demonstrate how the shape of the cosmic ray flux in the cut-off region, along
with the photon fraction, are useful indicators of the cutoff origin as well as
the local UHECR source distribution.


title:
Sign-Alternating Interaction Mediated by Strongly-Correlated Lattice
  Bosons

abstract:
  We reveal a generic mechanism of generating sign-alternating inter-site
interactions mediated by strongly correlated lattice bosons. The ground state
phase diagram of the two-component hard-core Bose-Hubbard model on a square
lattice at half-integer filling factor for each component, obtained by worm
algorithm Monte Carlo simulations, is strongly modified by these interactions
and features the solid+superfluid phase for strong anisotropy between the
hopping amplitudes. The new phase is a direct consequence of the effective
nearest-neighbor repulsion between "heavy" atoms mediated by the "light"
superfluid component. Due to their sign-alternating character, mediated
interactions lead to a rich variety of yet to be discovered quantum phases.
quantum phases.


title: Searching for substellar companions of young isolated neutron stars

abstract:
  Context: Only two planetary systems around old ms-pulsars are currently
known. Young radio pulsars and radio-quiet neutron stars cannot be covered by
the usually-applied radio pulse timing technique. However, finding substellar
companions around these neutron stars would be of great interest -- not only
because of the companion's possible exotic formation but also due to the
potential access to neutron star physics.
  Aims: We investigate the closest young neutron stars to search for substellar
companions around them.
  Methods: Young, thus warm substellar companions are visible in the Near
Infrared while the neutron star itself is much fainter. Four young neutron
stars are moving fast enough to enable a common proper motion search for
substellar companions within few years.
  Results. For Geminga, RX J0720.4-3125, RX J1856.6-3754, and PSR J1932+1059 we
did not find any co-moving companion down to 12, 15, 11, 42 Jupiter masses for
assumed ages of 1, 1, 1, 3.1 Myrs and distances of 250, 361, 167, 361 pc,
respectively. Near Infrared limits are presented for these four as well as five
other neutron stars for which we currently have only observations at one epoch.
  Conclusions: We conclude that young isolated neutron stars rarely have brown
dwarf companions.


title: Leptophilic Dark Matter

abstract:
  We describe a simple model of Dark Matter, which explains the PAMELA/ATIC
excesses while being consistent with all present constraints. The DAMA annual
modulation signal can also be explained for some values of the parameters. The
model consists of a Dark Sector containing a weakly coupled broken U(1) gauge
symmetry, under which only the Dark Matter state and the leptons are charged.


title: Hom-Algebras and Hom-Coalgebras

abstract:
  The aim of this paper is to develop the theory of Hom-coalgebras and related
structures. After reviewing some key constructions and examples of
quasi-deformations of Lie algebras involving twisted derivations and giving
rise to the class of quasi-Lie algebras incorporating Hom-Lie algebras, we
describe the notion and some properties of Hom-algebras and provide examples.
We introduce Hom-coalgebra structures, leading to the notions of Hom-bialgebra
and Hom-Hopf algebras and prove some fundamental properties and give examples.
Finally, we define the concept of Hom-Lie admissible Hom-coalgebra and provide
their classification based on subgroups of the symmetric group.


title:
A Comparison of Turbulent Thermal Convection Between Conditions of
  Constant Temperature and Constant Flux

abstract:
  We report the results of high resolution direct numerical simulations of
two-dimensional Rayleigh-B\'enard convection for Rayleigh numbers up to
$\Ra=10^{10}$ in order to study the influence of temperature boundary
conditions on turbulent heat transport. Specifically, we considered the extreme
cases of fixed heat flux (where the top and bottom boundaries are poor thermal
conductors) and fixed temperature (perfectly conducting boundaries). Both cases
display identical heat transport at high Rayleigh numbers fitting a power law
$\Nu \approx 0.138 \times \Ra^{.285}$ with a scaling exponent indistinguishable
from $2/7 = .2857...$ above $\Ra = 10^{7}$. The overall flow dynamics for both
scenarios, in particular the time averaged temperature profiles, are also
indistinguishable at the highest Rayleigh numbers. The findings are compared
and contrasted with results of recent three-dimensional simulations.


title: Cohomology of graph hypersurfaces associated to certain Feynman graphs

abstract:
  To any Feynman graph (with 2n edges) we can associate a hypersurface
X\subset\PP^{2n-1}. We study the middle cohomology H^{2n-2}(X) of such
hypersurfaces. S. Bloch, H. Esnault, and D. Kreimer (Commun. Math. Phys. 267,
2006) have computed this cohomology for the first series of examples, the wheel
with spokes graphs WS_n, n\geq 3. Using the same technique, we introduce the
generalized zigzag graphs and prove that W_5(H^{2n-2}(X))=\QQ(-2) for all of
them (with W_{*} the weight filtration). Next, we study primitively log
divergent graphs with small number of edges and the behavior of graph
hypersurfaces under the gluing of graphs.


title:
Theory of severe slowdown in the relaxation of rings and clusters with
  antiferromagnetic interactions

abstract:
  We show that in the severe slowing down temperature regime the relaxation of
antiferromagnetic rings and similar magnetic nanoclusters is governed by the
quasi-continuum portion of their quadrupolar fluctuation spectrum and not by
the lowest excitation lines. This is at the heart of the intriguing
near-universal power-law temperature dependence of the electronic correlation
frequency $\omega_c$ with an exponent close to 4. The onset of this behavior is
defined by an energy scale which is fixed by the lowest spin gap $\Delta_0$.
This explains why experimental curves of $\omega_c$ for different cluster sizes
and spins nearly coincide when $T$ is rescaled by $\Delta_0$.


title: On perfectly generating projective classes in triangulated categories

abstract:
  We say that a projective class in a triangulated category with coproducts is
perfect if the corresponding ideal is closed under coproducts of maps. We study
perfect projective classes and the associated phantom and cellular towers.
Given a perfect generating projective class, we show that every object is
isomorphic to the homotopy colimit of a cellular tower associated to that
object. Using this result and the Neeman's Freyd--style representability
theorem we give a new proof of Brown Representability Theorem.


title: Predicting the popularity of online content

abstract:
  We present a method for accurately predicting the long time popularity of
online content from early measurements of user access. Using two content
sharing portals, Youtube and Digg, we show that by modeling the accrual of
views and votes on content offered by these services we can predict the
long-term dynamics of individual submissions from initial data. In the case of
Digg, measuring access to given stories during the first two hours allows us to
forecast their popularity 30 days ahead with remarkable accuracy, while
downloads of Youtube videos need to be followed for 10 days to attain the same
performance. The differing time scales of the predictions are shown to be due
to differences in how content is consumed on the two portals: Digg stories
quickly become outdated, while Youtube videos are still found long after they
are initially submitted to the portal. We show that predictions are more
accurate for submissions for which attention decays quickly, whereas
predictions for evergreen content will be prone to larger errors.


title: Discrete multivariate distributions

abstract:
  This article brings in two new discrete distributions: multidimensional
Binomial distribution and multidimensional Poisson distribution. Those
distributions were created in eventology as more correct generalizations of
Binomial and Poisson distributions. Accordingly to eventology new laws take
into account full distribution of events. Also, in article its characteristics
and properties are described


title:
Chiral symmetry breaking in the truncated Coulomb Gauge II.
  Non-confining power law potentials

abstract:
  In this paper we study the breaking of chiral symmetry with non-confining
power-like potentials. The region of allowed exponents is identified and, after
the previous study of confining (positive exponent) potentials, we now
specialize in shorter range non-confining potentials, with a negative exponent.
These non-confining potentials are close to the Coulomb potential, and they are
also relevant as corrections to the linear confinement, and as models for the
quark potential at the deconfinement transition. The mass-gap equation is
constructed and solved, and the quarks mass, the chiral angle and the quark
energy are calculated analytically with a exponent expansion in the
neighbourhood of the Coulomb potential. It is demonstrated that chiral symmetry
breaking occurs, but only the chiral invariant false vacuum and a second
non-trivial vacuum exist. Moreover chiral symmetry breaking is led by the UV
part of the potential, with no IR enhancement of the quark mass. Thus the
breaking of chiral symmetry driven by non-confining potentials differs from the
one lead by confining potentials.


title:
Variable Evolved Stars and YSOs Discovered in the Large Magellanic Cloud
  using the SAGE Survey

abstract:
  We present initial results and source lists of variable sources in the Large
Magellanic Cloud (LMC) for which we detect thermal infrared variability from
the SAGE (Surveying the Agents of a Galaxy's Evolution) survey, which had 2
epochs of photometry separated by three months. The SAGE survey mapped a 7
degree by 7 degree region of the LMC using the IRAC and the MIPS instruments on
board Spitzer. Variable sources are identified using a combination of the IRAC
3.6, 4.5, 5.8, 8.0 \micron bands and the MIPS 24 \micron bands. An
error-weighted flux difference between the two epochs is used to assess the
variability. Of the ~ 3 million sources detected at both epochs we find ~ 2,000
variable sources for which we provide electronic catalogs. Most of the variable
sources can be classified as asymptotic giant branch (AGB) stars. A large
fraction (> 66%) of the extreme AGB stars are variable and only smaller
fractions of carbon-rich (6.1%) and oxygen-rich (2.0%) stars are detected as
variable. We also detect a population of variable young stellar object
candidates.


title: On the consistency of the Aoki-phase

abstract:
  Lattice QCD with two flavors of Wilson fermions can exhibit spontaneous
breaking of flavor and parity, with the resulting "Aoki phase" characterized by
the non-zero expectation value $<\bar\psi \gamma_5 \tau_3 \psi>\ne0$. This
phenomenon can be understood using the chiral effective theory appropriate to
the Symanzik effective action. Within this standard analysis, the
flavor-singlet pseudoscalar expectation value vanishes: $<i \bar\psi \gamma_5
\psi>=0$. A recent reanalysis has questioned this understanding, arguing that
either the Aoki-phase is unphysical, or that there are additional phases in
which $<i \bar\psi \gamma_5 \psi>\ne0$. The reanalysis uses the properties of
probability distribution functions for observables built of fermion fields and
expansions in terms of the eigenvalues of the hermitian Wilson-Dirac operator.
Here I show that the standard understanding of the Aoki-phase is, in fact,
consistent with the approach used in the reanalysis. Furthermore, if one
assumes that the standard understanding is correct, one can use the methods of
the reanalysis to derive lattice generalizations of the continuum sum rules of
Leutwyler and Smilga.


title: The influence of optical molasses in loading a shallow optical trap

abstract:
  We have examined loading of 85Rb atoms into a shallow Far-Off-Resonance Trap
(FORT) from an optical molasses and compared it to loading from a
Magneto-Optical Trap (MOT). We found that substantially more atoms could be
loaded into the FORT via an optical molasses as compared to loading from the
MOT alone. To determine why this was the case, we measured the rate of atoms
loaded into the FORT and the losses from the FORT during the loading process.
For both MOT and molasses loading, we examined atom load rate and losses over a
range of detunings as well as hyperfine pump powers. We found that the losses
induced during MOT loading were essentially the same as the losses induced
during molasses loading at the same MOT/molasses detuning. In contrast, load
rate of the molasses was higher than that of a MOT at a given detuning. This
caused the optical molasses to be able to load more atoms than the MOT.
Optimization of FORT loading form an optical molasses improved the number of
atoms we could trap by a factor of two over that of optimal loading from a MOT.


title:
Physical Origin and Generic Control of Magnonic Band Gaps of
  Dipole-Exchange Spin Waves in Width-Modulated-Nanostrip Waveguides

abstract:
  We report, for the first time, on a novel planar structure of
magnonic-crystal waveguides, made of a single magnetic material, in which the
allowed and forbidden bands of propagating dipole-exchange spin-waves can be
manipulated by the periodic modulation of different widths in thin-film
nanostrips. The origin of the presence of several magnonic wide band gaps and
the crucial parameters for controlling those band gaps of the order of ~10 GHz
are found by micromagnetic numerical and analytical calculations. This work can
offer a route to the potential application to broad-band spin-wave filters in
the GHz frequency range.


title: Spin Hall Effect of Excitons

abstract:
  Spin Hall effect for excitons in alkali halides and in Cu_2O is investigated
theoretically. In both systems, the spin Hall effect results from the Berry
curvature in k space, which becomes nonzero due to lifting of degeneracies of
the exciton states by exchange coupling. The trajectory of the excitons can be
directly seen as spatial dependence of the circularly polarized light emitted
from the excitons. It enables us to observe the spin Hall effect directly in
the real-space time.


title:
Robust Linear Processing for Downlink Multiuser MIMO System With
  Imperfectly Known Channel

abstract:
  This paper proposes a roust downlink multiuser MIMO scheme that exploits the
channel mean and antenna correlations to alleviate the performance penalty due
to the mismatch between the true and estimated CSI.


title: Puiseux power series solutions for systems of equations

abstract:
  We give an algorithm to compute term by term multivariate Puiseux series
expansions of series arising as local parametrizations of zeroes of systems of
algebraic equations at singular points. The algorithm is an extension of
Newton's method for plane algebraic curves replacing the Newton polygon by the
tropical variety of the ideal generated by the system. As a corollary we deduce
a property of tropical varieties of quasi-ordinary singularities.


title:
High energy resolution hard X-ray and gamma-ray imagers using CdTe diode
  devices

abstract:
  We developed CdTe double-sided strip detectors (DSDs or cross strip
detectors) and evaluated their spectral and imaging performance for hard X-rays
and gamma-rays. Though the double-sided strip configuration is suitable for
imagers with a fine position resolution and a large detection area, CdTe diode
DSDs with indium (In) anodes have yet to be realized due to the difficulty
posed by the segmented In anodes. CdTe diode devices with aluminum (Al) anodes
were recently established, followed by a CdTe device in which the Al anodes
could be segmented into strips. We developed CdTe double-sided strip devices
having Pt cathode strips and Al anode strips, and assembled prototype CdTe
DSDs. These prototypes have a strip pitch of 400 micrometer. Signals from the
strips are processed with analog ASICs (application specific integrated
circuits). We have successfully performed gamma-ray imaging spectroscopy with a
position resolution of 400 micrometer. Energy resolution of 1.8 keV (FWHM: full
width at half maximum) was obtained at 59.54 keV. Moreover, the possibility of
improved spectral performance by utilizing the energy information of both side
strips was demonstrated. We designed and fabricated a new analog ASIC, VA32TA6,
for the readout of semiconductor detectors, which is also suitable for DSDs. A
new feature of the ASIC is its internal ADC function. We confirmed this
function and good noise performance that reaches an equivalent noise charge of
110 e- under the condition of 3-4 pF input capacitance.


title: Training a Binary Classifier with the Quantum Adiabatic Algorithm

abstract:
  This paper describes how to make the problem of binary classification
amenable to quantum computing. A formulation is employed in which the binary
classifier is constructed as a thresholded linear superposition of a set of
weak classifiers. The weights in the superposition are optimized in a learning
process that strives to minimize the training error as well as the number of
weak classifiers used. No efficient solution to this problem is known. To bring
it into a format that allows the application of adiabatic quantum computing
(AQC), we first show that the bit-precision with which the weights need to be
represented only grows logarithmically with the ratio of the number of training
examples to the number of weak classifiers. This allows to effectively
formulate the training process as a binary optimization problem. Solving it
with heuristic solvers such as tabu search, we find that the resulting
classifier outperforms a widely used state-of-the-art method, AdaBoost, on a
variety of benchmark problems. Moreover, we discovered the interesting fact
that bit-constrained learning machines often exhibit lower generalization error
rates. Changing the loss function that measures the training error from 0-1
loss to least squares maps the training to quadratic unconstrained binary
optimization. This corresponds to the format required by D-Wave's
implementation of AQC. Simulations with heuristic solvers again yield results
better than those obtained with boosting approaches. Since the resulting
quadratic binary program is NP-hard, additional gains can be expected from
applying the actual quantum processor.


title:
Parametric Channel Estimation by Exploiting Hopping Pilots in Uplink
  OFDMA

abstract:
  This paper proposes a parametric channel estimation algorithm applicable to
uplink of OFDMA systems with pseudo-random subchannelization. It exploits the
hopping pilots to facilitate ESPRIT to estimate the delay subspace of the
multipath fading channel, and utilizes the global pilot tones to interpolate on
data subcarriers. Hence, it outperforms the traditional local channel
interpolators considerably.


title:
Decoherence-free quantum memory for photonic state using atomic
  ensembles

abstract:
  Large scale quantum information processing requires stable and long-lived
quantum memories. Here, using atom-photon entanglement, we propose an
experimentally feasible scheme to realize decoherence-free quantum memory with
atomic ensembles, and show one of its applications, remote transfer of unknown
quantum state, based on laser manipulation of atomic ensembles, photonic state
operation through optical elements, and single-photon detection with moderate
efficiency. The scheme, with inherent fault-tolerance to the practical noise
and imperfections, allows one to retrieve the information in the memory for
further quantum information processing within the reach of current technology.


title: Doppler Spread Estimation by Subspace Tracking for OFDM Systems

abstract:
  This paper proposes a novel maximum Doppler spread estimation algorithm for
OFDM systems with the comb-type pilot pattern. By tracking the drifting delay
subspace of the multipath channel, the time correlation function is measured at
a high accuracy, which accordingly improves the estimation accuracy of the
maximum Doppler spread considerably.