title: Boundary state of superstring in open string channel

abstract:
  We derive boundary state of superstring in the open string channel. It
describes the superconformal field theory of open string emission and
absorption by D-brane. We define the boundary state by conformal mappings from
upper half plane with operators inserted at two points corresponding to the
corners of semi-infinite strip. We obtain explicit oscillator forms
analytically for the fermion and superconformal ghost sectors. For the fermion
sector we compare this with numerical result obtained by using naive boundary
condition.


title: Improving the LP bound of a MILP by branching concurrently

abstract:
  We'll measure the differences of the dual variables and the gain of the
objective function when creating new problems, which each has one inequality
more than the starting LP-instance. These differences of the dual variables are
naturally connected to the branches. Then we'll choose those differences of
dual variables, so that for all combinations of choices at the connected
branches, all dual inequalities will hold for sure. By adding the gain of each
chosen branching, we get a total gain, which gives a better limit of the
original problem. By this technique it is also possible to create cuts.


title: Period Lengths for Iterated Functions

abstract:
  For random maps, the expected value of the order (i.e. the period of the
sequence of compositional iterates) is approximated asymptotically. It is much
smaller than the expected value for the product of the cycle lengths.


title: Black holes as local horizons

abstract:
  This talk gives a brief introduction to black hole horizons and their role in
black hole thermodynamics. In particular a distinction is made between
quasi-locally defined horizons and event horizons. Currently some new
techniques have led to interesting developments and the field seems to be
growing in two distinct directions. We will show how thermodynamics can equally
well be applied to locally defined horizons and discuss some recent results.
The emphasis is on giving simple intuitive pictures and mathematical details
are largely omitted.


title: Resource and Application Models for Advanced Grid Schedulers

abstract:
  As Grid computing is becoming an inevitable future, managing, scheduling and
monitoring dynamic, heterogeneous resources will present new challenges.
Solutions will have to be agile and adaptive, support self-organization and
autonomous management, while maintaining optimal resource utilisation.
Presented in this paper are basic principles and architectural concepts for
efficient resource allocation in heterogeneous Grid environment.


title: Measuring and Monitoring Grid Resource Utilisation

abstract:
  Effective resource utilisation monitoring and highly granular yet adaptive
measurements are prerequisites for a more efficient Grid scheduler. We present
a suite of measurement applications able to monitor per-process resource
utilisation, and a customisable tool for emulating observed utilisation models.


title: A Study of Grid Applications: Scheduling Perspective

abstract:
  As the Grid evolves from a high performance cluster middleware to a
multipurpose utility computing framework, a good understanding of Grid
applications, their statistics and utilisation patterns is required. This study
looks at job execution times and resource utilisations in a Grid environment,
and their significance in cluster and network dimensioning, local level
scheduling and resource management.


title: Hastening, delaying, or averting sudden death of quantum entanglement

abstract:
  The finite time end of entanglement between two decohering qubits can be
modified by local, unitary actions performed during the decohering process.
Depending on the time when such action is taken, the end can be speeded up or
slowed down, or even averted all together. This phenomenon offers practical
applications for the stabilization of entangled quantum states. Details
concerning hastening or delaying the finite time end of entanglement are
presented for two qubits which decay spontaneously into statistically
independent reservoirs.


title:
Exact solution of the extended Hubbard model in the atomic limit on the
  Bethe Lattice

abstract:
  We study the phase diagram at finite temperature of a system of Fermi
particles on the sites of the Bethe lattice with coordination number z and
interacting through onsite U and nearest-neighbor V interactions. This is a
physical realization of the extended Hubbard model in the atomic limit. By
using the equations of motion method, we exactly solve the model. For an
attractive intersite potential, we find, at half filling, a phase transition
towards a broken particle-hole symmetry state. The critical temperature, as a
function of the relevant parameters, has a re-entrant behavior as already
observed in the equivalent spin-1 Ising model on the Bethe lattice.


title: Observation and properties of the orbitally excited B_{s2}* Meson

abstract:
  We report the direct observation of the excited L=1 state B_{s2}* in fully
reconstructed decays to B+K-. The mass of the B_{s2}* meson is measured to be
{5839.6 +- 1.1 (stat.) +- 0.7 (syst.) MeV/c^2, and its production rate relative
to the B+ meson is measured to be [1.15 +- 0.23 (stat.) +- 0.13 (syst.)] %.


title:
Electric-field controlled spin reversal in a quantum dot with
  ferromagnetic contacts

abstract:
  Manipulation of the spin-states of a quantum dot by purely electrical means
is a highly desirable property of fundamental importance for the development of
spintronic devices such as spin-filters, spin-transistors and single-spin
memory as well as for solid-state qubits. An electrically gated quantum dot in
the Coulomb blockade regime can be tuned to hold a single unpaired spin-1/2,
which is routinely spin-polarized by an applied magnetic field. Using
ferromagnetic electrodes, however, the properties of the quantum dot become
directly spin-dependent and it has been demonstrated that the ferromagnetic
electrodes induce a local exchange-field which polarizes the localized spin in
the absence of any external fields. Here we report on the experimental
realization of this tunneling-induced spin-splitting in a carbon nanotube
quantum dot coupled to ferromagnetic nickel-electrodes. We study the
intermediate coupling regime in which single-electron states remain well
defined, but with sufficiently good tunnel-contacts to give rise to a sizable
exchange-field. Since charge transport in this regime is dominated by the
Kondo-effect, we can utilize this sharp many-body resonance to read off the
local spin-polarization from the measured bias-spectroscopy. We show that the
exchange-field can be compensated by an external magnetic field, thus restoring
a zero-bias Kondo-resonance, and we demonstrate that the exchange-field itself,
and hence the local spin-polarization, can be tuned and reversed merely by
tuning the gate-voltage. This demonstrates a very direct electrical control
over the spin-state of a quantum dot which, in contrast to an applied magnetic
field, allows for rapid spin-reversal with a very localized addressing.


title:
The rare decays $B^+_u\to\pi^+\ell^+\ell^-$, $\rho^+\ell^+\ell^-$ and
  $B^0_d\to \ell^+\ell^-$ in the R-parity violating supersymmetry

abstract:
  We study the rare decays $B^{+}_u\to \pi^{+}\ell^{+}\ell^{-}$,
$\rho^{+}\ell^{+}\ell^{-}$ and $B^{0}_d \to \ell^{+} \ell^{-}(\ell=e,\mu)$ in
the R-parity violating supersymmetric standard model. From the latest upper
limits of $\mathcal{B}(B^+_u\to\pi^+\ell^+\ell^-)$ and
$\mathcal{B}(B^0_d\to\ell^+\ell^-)$, we have derived new upper bounds on the
relevant R-parity violating couplings products, which are stronger than the
existing ones. Using the constrained parameter space, we present the R-parity
violating effects on the branching ratios and the forward-backward asymmetries
of these decays. We find that $\mathcal{B}(B^0_d\to \ell^+\ell^-)$ and
$\mathcal{B}(B^+_u \to\rho^+\ell^+\ell^-)$ could be enhanced several orders by
the R-parity violating sneutrino and squark exchanges, respectively. The
R-parity violating effects on the dilepton invariant mass spectra of $B^+_u\to
\pi^+\ell^+\ell^-$, $\rho^+\ell^+\ell^-$ and the normalized forward-backward
asymmetry $\mathcal{A}_{FB}(B^+_u\to\pi^+\ell^+\ell^-)$ and
$\mathcal{A}_{FB}(B^+_u \to\rho^+\ell^+\ell^-)$ are studied in detail. Our
results could be used to probe the R-parity violating effects and will
correlate with searches for the direct R-parity violating signals at the future
experiments.


title:
The Formation of Hydrogen Deficient Stars through Common Envelope
  Evolution

abstract:
  We present preliminary results from Smooth Particle Hydrodynamics (SPH)
simulations of common envelope evolution. We qualitatively compare the
interaction between a 0.9M red giant with two different companion masses: a
0.05M brown dwarf and a 0.25M white dwarf companion.


title:
Single Spin Effects in Collisions of Hadrons and Heavy Ions at High
  Energy

abstract:
  Experimental data on transverse single-spin asymmetry, hyperon polarization
and vector meson alignment in h+h, h+A and A+A-collisions have been analyzed. A
new mechanism for the origin of single spin effects is proposed, which takes
into account the interaction of massive constituent quarks via their
chromomagnetic moment with an effective inhomogeneous chromomagnetic field of
strings, produced after the initial color exchange. Quark spin precession in
the color field is taken into account, which can be the reason for an
oscillation of the single spin observables as a function of Feynman $x_{F}$ and
its energy dependence. The model predictions are compared with the experimental
data, in particular with the heavy ion collision data. The data are consistent
with a large negative anomalous chromomagnetic moment of the constituent quarks
which is predicted in the instanton model.


title: Tensor product for symmetric monoidal categories

abstract:
  We introduce a tensor product for symmetric monoidal categories with the
following properties. Let SMC denote the 2-category with objects small
symmetric monoidal categories, arrows symmetric monoidal functors and 2-cells
monoidal natural transformations. Our tensor product together with a suitable
unit is part of a structure on SMC that is a 2-categorical version of the
symmetric monoidal closed categories. This structure is surprisingly simple. In
particular the arrows involved in the associativity and symmetry laws for the
tensor and in the unit cancellation laws are 2-natural and satisfy coherence
axioms which are strictly commuting diagrams. We also show that the category
quotient of SMC by the congruence generated by its 2-cells admits a symmetric
monoidal closed structure.


title: Self-Organising management of Grid environments

abstract:
  This paper presents basic concepts, architectural principles and algorithms
for efficient resource and security management in cluster computing
environments and the Grid. The work presented in this paper is funded by
BTExacT and the EPSRC project SO-GRM (GR/S21939).


title: Enabling Adaptive Grid Scheduling and Resource Management

abstract:
  Wider adoption of the Grid concept has led to an increasing amount of
federated computational, storage and visualisation resources being available to
scientists and researchers. Distributed and heterogeneous nature of these
resources renders most of the legacy cluster monitoring and management
approaches inappropriate, and poses new challenges in workflow scheduling on
such systems. Effective resource utilisation monitoring and highly granular yet
adaptive measurements are prerequisites for a more efficient Grid scheduler. We
present a suite of measurement applications able to monitor per-process
resource utilisation, and a customisable tool for emulating observed
utilisation models. We also outline our future work on a predictive and
probabilistic Grid scheduler. The research is undertaken as part of UK
e-Science EPSRC sponsored project SO-GRM (Self-Organising Grid Resource
Management) in cooperation with BT.


title: Managing Uncertainty: A Case for Probabilistic Grid Scheduling

abstract:
  The Grid technology is evolving into a global, service-orientated
architecture, a universal platform for delivering future high demand
computational services. Strong adoption of the Grid and the utility computing
concept is leading to an increasing number of Grid installations running a wide
range of applications of different size and complexity. In this paper we
address the problem of elivering deadline/economy based scheduling in a
heterogeneous application environment using statistical properties of job
historical executions and its associated meta-data. This approach is motivated
by a study of six-month computational load generated by Grid applications in a
multi-purpose Grid cluster serving a community of twenty e-Science projects.
The observed job statistics, resource utilisation and user behaviour is
discussed in the context of management approaches and models most suitable for
supporting a probabilistic and autonomous scheduling architecture.


title:
Intermediate long X-ray bursts from the ultra-compact binary source SLX
  1737-282

abstract:
  Aims: The low persistent X-ray burster source SLX 1737-282 is classified as
an ultra-compact binary candidate. We compare the data on SLX 1737-282 with the
other similar objects and attempt to derive constraints on the physical
processes responsible for the formation of intermediate long bursts. Methods:
Up to now only three intermediate long bursts, all with duration between ~15-30
minutes, have been recorded for SLX 1737-282. The properties of two
intermediate long X-ray bursts observed by INTEGRAL from SLX 1737-282 are
investigated. The broadband spectrum of the persistent emission in the 3-100
keV energy band is studied with the INTEGRAL data. Results: The persistent
emission is measured to be < 1% Eddington luminosity. From the photospheric
radius expansion observed during the bursts we derive the source distance at
7.3 kpc. The observed intermediate long burst properties from SLX 1737-282 are
consistent with helium ignition at the column depth of 7-8 x 10E-9 g cm-2 and a
burst energy release of 1E41 erg. The apparent recurrence time of ~80 days
between the intermediate long bursts from SLX 1737-282 suggests a regime of
unstable burning of a thick, pure helium layer slowly accreted from a helium
donor star.


title:
The Monitor project: Rotation of low-mass stars in the open cluster NGC
  2547

abstract:
  We report on the results of an I-band time-series photometric survey of NGC
2547 using the MPG/ESO 2.2m telescope with WFI, achieving better than 1%
photometric precision per data point over 14 <~ I <~ 18. Candidate cluster
members were selected from a V vs V-I colour magnitude diagram over 12.5 < V <
24 (covering masses from 0.9 Msol down to below the brown dwarf limit), finding
800 candidates, of which we expect ~330 to be real cluster members, taking into
account contamination from the field (which is most severe at the extremes of
our mass range). Searching for periodic variations in these gave 176 detections
over the mass range 0.1 <~ M/Msol <~ 0.9. The rotation period distributions
were found to show a clear mass-dependent morphology, qualitatively
intermediate between the distributions obtained from similar surveys in NGC
2362 and NGC 2516, as would be expected from the age of this cluster. Models of
the rotational evolution were investigated, finding that the evolution from NGC
2362 to NGC 2547 was qualitatively reproduced (given the uncertainty in the age
of NGC 2547) by solid body and core-envelope decoupled models from our earlier
NGC 2516 study without need for significant modification.


title: Assessing statistical significance of periodogram peaks

abstract:
  The least-squares (or Lomb-Scargle) periodogram is a powerful tool which is
used routinely in many branches of astronomy to search for periodicities in
observational data. The problem of assessing statistical significance of
candidate periodicities for different periodograms is considered. Based on
results in extreme value theory, improved analytic estimations of false alarm
probabilities are given. They include an upper limit to the false alarm
probability (or a lower limit to the significance). These estimations are
tested numerically in order to establish regions of their practical
applicability.


title: X-ray Observables of Magnetically Dominated Cavities in Clusters

abstract:
  We present results from magneto-hydrodynamic jet simulations in the
magnetically dominated regime and find that they inflate cavities into the
intracluster medium. Mock Chandra X-ray observations of our simulations show a
strong resemblance to real cavities observed in X-ray images of clusters, both
in terms of their morphology and thermodynamic structure. An analysis of the
evolution of bubble sizes in the multi-cavity system Hydra A, as well as in a
large sample of 64 cavities in 32 clusters shows that bubbles tend to expand
much faster than expected in the purely adiabatic regime. Instead, we find that
the bubbles follow more closely a trend predicted by our current-carrying jet
models.


title:
Summary of session A4 at the GRG18 conference: Alternative Theories of
  Gravity

abstract:
  More than 50 abstracts were submitted to the A4 session on "Alternatives
Theories of Gravity" at the GRG18 conference. About 30 of them were scheduled
as oral presentations, that we summarize below. We do not intend to give a
critical review, but rather pointers to the corresponding papers. The main
topics were (i) brane models both from the mathematical and the
phenomenological viewpoints; (ii) Einstein-Gauss-Bonnet gravity in higher
dimensions or coupled to a scalar field; (iii) modified Newtonian dynamics
(MOND); (iv) scalar-tensor and f(R) theories; (v) alternative models involving
Lorentz violations, noncommutative spacetimes or Chern-Simons corrections.


title: Magnetic resonance as an orbital state probe

abstract:
  Magnetic resonance in ordered state is shown to be the direct method for
distinguishing the orbital ground state. The example of perovskite titanates,
particularly, LaTiO3 and YTiO3, is considered. External magnetic field
resonance spectra of these crystals reveal glaring qualitative dependence on
assumed orbital state of the compounds: orbital liquid or static orbital
structure. Theoretical basis for using the method as an orbital state probe is
grounded.


title:
Ueber Eigenwerte, Integrale und pi^2/6: Die Idee der Spurformel (On
  eigenvalues, integrals and pi^2/6: The idea of the trace formula)

abstract:
  This is an expository article that results from a talk given to second year
students at Oldenburg university. The aim of the talk was to show what
beautiful and unexpected results may be obtained if one plays with daring
analogies in a way that is usually not done in undergraduate education
(unfortunately): We start from the fact that the sum of diagonal entries of a
symmetric matrix equals the sum of its eigenvalues. We then guess an analogous
formula where the matrix is replaced by a function of two real variables and
sums are replaced by integrals in a systematic way. We show that this is indeed
a worthwhile process: In a special case it yields that the sum of inverse
squares of the positive integers is pi^2/6. Finally, an outline of the proof of
the guessed formula is given, and further applications, for example to the
connection between billiards and the frequencies of a drum, are explained.


title:
On the enhanced cosmic-ray ionization rate in the diffuse cloud towards
  Zeta Persei

abstract:
  The spatial distribution of the cosmic-ray flux is important in understanding
the Interstellar Medium (ISM) of the Galaxy. This distribution can be analyzed
by studying different molecular species along different sight lines whose
abundances are sensitive to the cosmic-ray ionization rate. Recently several
groups have reported an enhanced cosmic-ray ionization rate in diffuse clouds
compared to the standard value, zeta(average)=2.5e-17 s^-1, measured toward
dense molecular clouds. In an earlier work we reported an enhancement in the
cosmic ray rate of 20 towards HD185418. McCall et al. have reported
enhancements of 48 towards zeta Persei based on the observed abundance of
H$_{3}^+ while Le Petit et al. found a cosmic ray enhancement of ~10 to be
consistent with their models for this same sight line. Here we revisit zeta
Persei and perform a detailed calculation using a self-consistent treatment of
the hydrogen chemistry, grain physics, energy and ionization balance, and
excitation physics. We show that the value of zeta deduced from the H$_{3}^+$
column density in the diffuse region of the sightline depends strongly on the
properties of the grains because they remove free electrons and change the
hydrogen chemistry. The observations are largely consistent with a cosmic ray
enhancement of 40, with several diagnostics indicating higher values. This
underscores the importance of a full treatment of grain physics in studies of
interstellar chemistry.


title: QCD Thermodynamics

abstract:
  Recent results on QCD thermodynamics are presented. The nature of the T>0
transition is determined, which turns out to be an analytic cross-over. The
absolute scale for this transition is calculated. The temperature dependent
static potential is given. The results were obtained by using a Symanzik
improved gauge and stout-link improved fermionic action. In order to approach
the continuum limit four different sets of lattice spacings were used with
temporal extensions N_t=4, 6, 8 and 10 (they correspond to lattice spacings a
\sim 0.3, 0.2, 0.15 and 0.12 fm). A new technique is presented, which --in
contrast to earlier methods-- enables one to determine the equation of state at
very large temperatures.


title:
Linear Stark Shifts to Measure the Fr Weak Nuclear Charge with Small
  Atom Samples

abstract:
  We study the chirality of ground-state alkali atoms in E and B fields,
dressed with a circularly-polarized laser beam close-detuned from an
E-field-assisted forbidden transition, such as 7S-8S in Fr. We predict a parity
violating energy shift of their sublevels, linear in E, and the weak nuclear
charge Q_W$. A dressing beam of 10 kW/cm$^2$ at 506 nm produces a shift of
$\sim100 \mu$Hz at E=100 V/cm, B $\gtrsim$30 mG. It should be observable with
$\sim 10^4$ Fr atoms confined in an optical dipole trap. We discuss optimal
conditions, parameter reversals and a calibration procedure to measure $Q_W$.


title: Structure constants of the OSP(1|2) WZNW model

abstract:
  We propose exact formulas for the 2- and 3-point functions of the WZNW model
on the non-compact supergroup OSP(1|2). Using the path integral approach that
was recently developed in arXiv:0706.1030 we show how local correlation
functions in the OSP(p|2) WZNW models can be obtained from those of N=p
supersymmetric Liouville field theory for p=1,2. We then employ known results
on correlators in N=1 Liouville theory to determine the structure constants of
the OSP(1|2) theory.


title: Twisted Gromov-Witten r-spin potential and Givental's quantization

abstract:
  The universal curve p:C->\Mbar over the moduli space \Mbar of stable r-spin
maps to a target K\"ahler manifold X carries a universal spinor bundle L->C.
Therefore the moduli space \Mbar itself carries a natural K-theory class Rp_*L.
  We introduce a twisted r-spin Gromov-Witten potential of X enriched with
Chern characters of Rp_*L. We show that the twisted potential can be
reconstructed from the ordinary r-spin Gromov-Witten potential of X via an
operator that assumes a particularly simple form in Givental's quantization
formalism.


title:
Origin of ferromagnetic response in diluted magnetic semiconductors and
  oxides

abstract:
  This paper reviews the present understanding of the origin of ferromagnetic
response of diluted magnetic semiconductors and diluted magnetic oxides as well
as in some nominally magnetically undoped materials. It is argued that these
systems can be grouped into four classes. To the first belong composite
materials in which precipitations of a known ferromagnetic, ferrimagnetic or
antiferromagnetic compound account for magnetic characteristics at high
temperatures. The second class forms alloys showing chemical nano-scale phase
separation into the regions with small and large concentrations of the magnetic
constituent. To the third class belong (Ga,Mn)As, heavily doped p-(Zn,Mn)Te,
and related semiconductors. In these solid solutions the theory built on p-d
Zener's model of hole-mediated ferromagnetism and on either the Kohn-Luttinger
kp theory or the multi-orbital tight-binding approach describes qualitatively,
and often quantitatively many relevant properties. Finally, in a number of
carrier-doped DMS and DMO a competition between long-range ferromagnetic and
short-range antiferromagnetic interactions and/or the proximity of the
localisation boundary lead to an electronic nano-scale phase separation.


title: ASPID-SR: Prototype of a VO-compliant Science-Ready Data Archive

abstract:
  ASPID stands for the "Archive of Spectral, Photometric, and Interferometric
Data". The world largest collection of raw 3D spectroscopic observations of
galactic and extragalactic sources is provided. ASPID-SR is a prototype of an
archive of heterogeneous science ready data, fed by ASPID, where we try to
exploit all the power of the IVOA Characterisation Data Model. Multi-level
Characterisation metadata is provided for every dataset. The archive provides
powerful metadata query mechanism with access to every data model element,
vital for the efficient scientific usage of a complex informational system. We
provide a set of access interfaces: SIAP/SSAP, HTTP-based characterisation
metadata query, Web-service accepting ADQL/x.


title:
Comprehensive Metadata Query Interface for Heterogeneous Data Archives
  Based on Open Source PostgreSQL ORDBMS

abstract:
  We use PostgreSQL DBMS for storing XML metadata, described by the IVOA
Characterisation Data Model. Initial XML type support in the PostgreSQL has
recently been implemented. We make heavy use of this feature in order to
provide comprehensive search over Characterisation metadata tree. We built a
prototype of the Characterisation metadata query service, implementing two
access methods: (1) HTTP-GET/POST based interface implements almost direct
translation of the query parameter name into XPath of the data model element in
the XML serialisation; (2) Web-Service based interface to receive XQuery which
is also directly translated into XPath. This service will be used in the
ASPID-SR archive, containing science-ready data obtained with the Russian 6-m
telescope.


title:
Origin and control of ferromagnetism in dilute magnetic semiconductors
  and oxides

abstract:
  The author reviews the present understanding of the hole-mediated
ferromagnetism in magnetically doped semiconductors and oxides as well as the
origin of high temperature ferromagnetism in materials containing no valence
band holes. It is argued that in these systems spinodal decomposition into
regions with a large and a small concentration of magnetic component takes
place. This self-organized assembling of magnetic nanocrystals can be
controlled by co-doping and growth conditions. Functionalities of these
multicomponent systems are described together with prospects for their
applications in spintronics, nanoelectronics, photonics, plasmonics, and
thermoelectrics.


title: Automatic Coding Rule Conformance Checking Using Logic Programs

abstract:
  Some approaches to increasing program reliability involve a disciplined use
of programming languages so as to minimise the hazards introduced by
error-prone features. This is realised by writing code that is constrained to a
subset of the a priori admissible programs, and that, moreover, may use only a
subset of the language. These subsets are determined by a collection of
so-called coding rules.


title:
A Prolog-based Environment for Reasoning about Programming Languages
  (Extended abstract)

abstract:
  ECLAIR is a Prolog-based prototype system aiming to provide a functionally
complete environment for the study, development and evaluation of programming
language analysis and implementation tools. In this paper, we sketch the
overall structure of the system, outlining the main methodologies and
technologies underlying its components. We also discuss the appropriateness of
Prolog as the implementation language for the system: besides highlighting its
strengths, we also point out a few potential weaknesses, hinting at possible
solutions.


title:
Poincar\'e duality for $K$-theory of equivariant complex projective
  spaces

abstract:
  We make explicit Poincar\'{e} duality for the equivariant $K$-theory of
equivariant complex projective spaces. The case of the trivial group provides a
new approach to the $K$-theory orientation.


title:
A theoretical analysis of the resolution due to diffusion and
  size-dispersion of particles in deterministic lateral displacement devices

abstract:
  We present a model including diffusion and particle-size dispersion for
separation of particles in deterministic lateral displacement devices also
known as bumper arrays. We determine the upper critical diameter for
diffusion-dominated motion and the lower critical diameter for pure
convection-induced displacement. Our model explains the systematic deviation,
observed for small particles in several experiments, from the critical diameter
for separation given by simple laminar flow considerations.


title: Compiling ER Specifications into Declarative Programs

abstract:
  This paper proposes an environment to support high-level database programming
in a declarative programming language. In order to ensure safe database
updates, all access and update operations related to the database are generated
from high-level descriptions in the entity- relationship (ER) model. We propose
a representation of ER diagrams in the declarative language Curry so that they
can be constructed by various tools and then translated into this
representation. Furthermore, we have implemented a compiler from this
representation into a Curry program that provides access and update operations
based on a high-level API for database programming.


title: Adaptive multiresolution for wavelet analysis

abstract:
  We present a new method of wavelet packet decomposition to be used in
gravitational wave detection. An issue in wavelet analysis is what is the
time-frequency resolution which is best suited to analyze data when in quest of
a signal of unknown shape, like a burst. In the other wavelet methods currently
employed, like LIGO WaveBurst, the analysis is performed at some trial
resolutions. We propose a decomposition which automatically selects at any
frequency the best resolution. The criterion for resolution selection is based
on minimization of a function of the data, named entropy in analogy with the
information theory. As a qualitative application we show how a multiresolution
time-frequency scalogram looks in the case of a sample signal injected over
Gaussian noise. For a more quantitative application of the method we tested its
efficiency as a non-linear filter of simulated data for burst searches, finding
that it is able to lower the false alarm rate of the WaveBurst algorithm with
negligible effects on the efficiency.


title: Intermittent estimation of stationary time series

abstract:
  Let $\{X_n\}_{n=0}^{\infty}$ be a stationary real-valued time series with
unknown distribution. Our goal is to estimate the conditional expectation of
$X_{n+1}$ based on the observations $X_i$, $0\le i\le n$ in a strongly
consistent way. Bailey and Ryabko proved that this is not possible even for
ergodic binary time series if one estimates at all values of $n$. We propose a
very simple algorithm which will make prediction infinitely often at carefully
selected stopping times chosen by our rule. We show that under certain
conditions our procedure is strongly (pointwise) consistent, and $L_2$
consistent without any condition. An upper bound on the growth of the stopping
times is also presented in this paper.


title: Noise threshold for universality of 2-input gates

abstract:
  Evans and Pippenger showed in 1998 that noisy gates with 2 inputs are
universal for arbitrary computation (i.e. can compute any function with bounded
error), if all gates fail independently with probability epsilon and
epsilon<theta, where theta is roughly 8.856%.
  We show that formulas built from gates with 2 inputs, in which each gate
fails with probability at least theta cannot be universal. Hence, there is a
threshold on the tolerable noise for formulas with 2-input gates and it is
theta. We conjecture that the same threshold also holds for circuits.


title: The Twisted Higher Harmonic Signature for Foliations

abstract:
  We prove that the higher harmonic signature of an even dimensional oriented
Riemannian foliation of a compact Riemannian manifold with coefficients in a
leafwise U(p,q)-flat complex bundle is a leafwise homotopy invariant. We also
prove the leafwise homotopy invariance of the twisted higher Betti classes.
Consequences for the Novikov conjecture for foliations and for groups are
investigated.
  Replaces The Higher Harmonic Signature for Foliations I: The Untwisted Case,
and contains significant improvements.


title:
The IceCube Collaboration: contributions to the 30th International
  Cosmic Ray Conference (ICRC 2007)

abstract:
  This paper bundles 40 contributions by the IceCube collaboration that were
submitted to the 30th International Cosmic Ray Conference ICRC 2007. The
articles cover studies on cosmic rays and atmospheric neutrinos, searches for
non-localized, extraterrestrial electron, muon and tau neutrino signals, scans
for steady and intermittent neutrino point sources, searches for dark matter
candidates, magnetic monopoles and other exotic particles, improvements in
analysis techniques, as well as future detector extensions.
  The IceCube observatory will be finalized in 2011 to form a cubic-kilometer
ice-Cherenkov detector at the location of the geographic South Pole. At the
present state of construction, IceCube consists of 52 paired IceTop surface
tanks and 22 IceCube strings with a total of 1426 Digital Optical Modules
deployed at depths up to 2350 m. The observatory also integrates the 19 string
AMANDA subdetector, that was completed in 2000 and extends IceCube's reach to
lower energies. Before the deployment of IceTop, cosmic air showers were
registered with the 30 station SPASE-2 surface array.
  IceCube's low noise Digital Optical Modules are very reliable, show a uniform
response and record waveforms of arriving photons that are resolvable with
nanosecond precision over a large dynamic range. Data acquisition,
reconstruction and simulation software are running in production mode and the
analyses, profiting from the improved data quality and increased overall
sensitivity, are well under way.


title: Investigations of the NS-alpha model using a lid-driven cavity flow

abstract:
  In this paper we investigate a subgrid model based on an anisotropic version
of the NS-$\alpha$ model using a lid-driven cavity flow at a Reynolds number of
10,000. Previously the NS-$\alpha$ model has only been used numerically in the
isotropic form. The subgrid model is developed from the Eulerian-averaged
anisotropic equations [Holm, \textit{Physica D}, v.133, pp 215-269, 1999]. It
was found that when $\alpha^{2}$ was based on the mesh numerical oscillations
developed which manifested themselves in the appearance of streamwise vortices
and a `mixing out' of the velocity profile. This is analogous to the
Craik-Leibovich mechanism, with the difference being that the oscillations here
are not physical but numerical. The problem could be traced back to the
discontinuity in $\alpha^{2}$ encountered when $\alpha^{2}=0$ on the endwalls.
An alternative definition of $\alpha^{2}$ based on velocity gradients, rather
than mesh spacing, is proposed and tested. Using this definition the results
with the model shown a significant improvement. The splitting of the downstream
wall jet, rms and shear stress profiles are correctly captured a coarse mesh.
The model is shown to predict both positive and negative energy transfer in the
jet impingement region, in qualitative agreement with DNS results.


title: Energies of ions in water and nanopores within Density Functional Theory

abstract:
  Accurate calculations of electrostatic potentials and treatment of substrate
polarizability are critical for predicting the permeation of ions inside
water-filled nanopores. The {\it ab initio} molecular dynamics method (AIMD),
based on Density Functional Theory (DFT), accounts for the polarizability of
materials, water, and solutes, and it should be the method of choice for
predicting accurate electrostatic energies of ions. In practice, DFT coupled
with the use of periodic boundary conditions in a charged system leads to large
energy shifts. Results obtained using different DFT packages may vary because
of the way pseudopotentials and long-range electrostatics are implemented.
Using maximally localized Wannier functions, we apply robust corrections that
yield relatively unambiguous ion energies in select molecular and aqueous
systems and inside carbon nanotubes. Large binding energies are predicted for
ions in metallic carbon nanotube arrays, while with consistent definitions
Na$^+$ and Cl$^-$ energies are found to exhibit asymmetries comparable with
those computed using non-polarizable water force fields.


title: Data Transmission in the Fourth Dimension

abstract:
  Alice wants to send an arbitrary binary word to Bob. We show here that there
is no problem for her to do that with only two bits. Of course, we consider
here information like a signal in 4D.


title: Observations of Transient Active Region Heating with Hinode

abstract:
  We present observations of transient active region heating events observed
with the Extreme Ultraviolet Imaging Spectrometer (EIS) and X-ray Telescope
(XRT) on Hinode. This initial investigation focuses on NOAA active region 10940
as observed by Hinode on February 1, 2007 between 12 and 19 UT. In these
observations we find numerous examples of transient heating events within the
active region. The high spatial resolution and broad temperature coverage of
these instruments allows us to track the evolution of coronal plasma. The
evolution of the emission observed with XRT and EIS during these events is
generally consistent with loops that have been heated and are cooling. We have
analyzed the most energetic heating event observed during this period, a small
GOES B-class flare, in some detail and present some of the spectral signatures
of the event, such as relative Doppler shifts at one of the loop footpoints and
enhanced line widths during the rise phase of the event. While the analysis of
these transient events has the potential to yield insights into the coronal
heating mechanism, these observations do not rule out the possibility that
there is a strong steady heating level in the active region. Detailed
statistical analysis will be required to address this question definitively.


title: Critical values of moment maps on quantizable manifolds

abstract:
  Let $M$ be a quantizable symplectic manifold acted on by $T=(S^1)^r$ in a
Hamiltonian fashion and $J$ a moment map for this action. Suppose that the set
$M^{T}$ of fixed points is discrete and denote by ${\alpha}_{pj}\in{\mathbb
Z}^r$ the weights of the isotropy representation at $p$. By means of the
$\alpha_{pj}$'s we define a partition ${\mathcal Q}_+$, ${\mathcal Q}_-$ of
$M^T$. (When $r=1$, ${\mathcal Q}_{\pm}$ will be the set of fixed points such
that the half of the Morse index of $J$ at them is even (odd)). We prove the
existence of a map $\pi_{\pm}:{\mathcal Q}_{\pm}\to{\mathcal Q}_{\mp}$ such
that $J(q)-J(\pi_{\pm}(q))\in I_{\mp}$, for all $q\in {\mathcal Q}_{\pm}$,
where $I_{\pm}$ is the lattice generated by the $\alpha_{pj}$'s with
$p\in{\mathcal Q}_{\pm}.$ We define partition functions $N_p$ similar to the
ones of Kostant \cite{Gui} and we prove that $\sum_{p\in{\mathcal
Q}_+}N_p(l)=\sum_{p\in{\mathcal Q}_-}N_p(l)$, for any $l\in{\mathbb Z}^r$ with
$|l|$ sufficiently large.


title: Dark energy FRW cosmology - dynamical system reconstruction

abstract:
  We develop a simple method of dark energy reconstruction using a geometrical
form of the luminosity-distance relation. In this method the FRW dynamical
system with dark energy is reconstructed instead of the equation of state
parameter. We give several examples which illustrate the usefulness of our
method in fitting the redshift transition from the decelerating to accelerating
phase as the value of the Hubble function at the transition.


title: Detecting Order and Chaos by the Linear Dependence Index (LDI) Method

abstract:
  We introduce a new methodology for a fast and reliable discrimination between
ordered and chaotic orbits in multidimensional Hamiltonian systems which we
call the Linear Dependence Index (LDI). The new method is based on the recently
introduced theory of the Generalized Alignment Indices (GALI). LDI takes
advantage of the linear dependence (or independence) of deviation vectors of a
given orbit, using the method of Singular Value Decomposition at every time
step of the integration. We show that the LDI produces estimates which
numerically coincide with those of the GALI method for the same number of $m$
deviation vectors, while its main advantage is that it requires considerable
less CPU time than GALI especially in Hamiltonian systems of many degrees of
freedom


title: On the integration of Poisson homogeneous spaces

abstract:
  We study a reduction procedure for describing the symplectic groupoid of a
Poisson homogeneous space obtained by quotient of a coisotropic subgroup. We
perform it as a reduction of the Lu-Weinstein symplectic groupoid integrating
Poisson Lie groups, that is suitable even for the non complete case.


title:
On the Asymptotic Solution for the Fourier-Bessel Multiple Scattering
  Coefficients of an Infinite Grating of Insulating Dielectric Circular
  Cylinders at Oblique Incidence

abstract:
  In this article, we present the asymptotic solution for the matrix system of
equations representing the multiple scattering coefficients of an infinite
grating of insulating dielectric circular cylinders associated with vertically
polarized obliquely incident plane electromagnetic waves.


title: Dyson-Schwinger Equation and Quantum Phase Transitions in Massless QCD

abstract:
  We study the stability of the highest symmetric solution (Wigner-solution) of
Dyson-Schwinger equations in chiral limit and at zero temperature. Our results
confirm that if the chemical potential is not very large, the QCD vacuum is in
the chiral symmetry breaking phase and the quantum phase-transition of the
chiral symmetry restoration is in first order. Meanwhile it seems that there is
not competition between chiral symmetry breaking phase and color
superconductivity phase since the color superconductivity phase appears only if
the chemical potential is very large. Moreover, we propose that chiral symmetry
breaking arises from the positive feedback with respect to the mass
perturbation.


title: Discriminating spin through quantum interference

abstract:
  Many of the proposed solutions to the hierarchy and naturalness problems
postulate new `partner' fields to the standard model particles. Determining the
spins of these new particles will be critical in distinguishing among the
various possible SM extensions, yet proposed methods rely on the underlying
models. We propose a new model-independent method for spin measurements which
takes advantage of quantum interference among helicity states. We demonstrate
that this method will be able to discriminate scalar particles from higher spin
states at the ILC, and discuss application to higher spins and possible uses at
the LHC.


title: Properties of tunnel Josephson junctions with a ferromagnetic interlayer

abstract:
  We investigate superconductor/insulator/ferromagnet/superconductor (SIFS)
tunnel Josephson junctions in the dirty limit, using the quasiclassical theory.
We formulate a quantitative model describing the oscillations of critical
current as a function of thickness of the ferromagnetic layer and use this
model to fit recent experimental data. We also calculate quantitatively the
density of states (DOS) in this type of junctions and compare DOS oscillations
with those of the critical current.


title: Shannon Theoretic Limits on Noisy Compressive Sampling

abstract:
  In this paper, we study the number of measurements required to recover a
sparse signal in ${\mathbb C}^M$ with $L$ non-zero coefficients from compressed
samples in the presence of noise. For a number of different recovery criteria,
we prove that $O(L)$ (an asymptotically linear multiple of $L$) measurements
are necessary and sufficient if $L$ grows linearly as a function of $M$. This
improves on the existing literature that is mostly focused on variants of a
specific recovery algorithm based on convex programming, for which
$O(L\log(M-L))$ measurements are required. We also show that $O(L\log(M-L))$
measurements are required in the sublinear regime ($L = o(M)$).


title: Nonparametric inference for ergodic, stationary time series

abstract:
  The setting is a stationary, ergodic time series. The challenge is to
construct a sequence of functions, each based on only finite segments of the
past, which together provide a strongly consistent estimator for the
conditional probability of the next observation, given the infinite past.
Ornstein gave such a construction for the case that the values are from a
finite set, and recently Algoet extended the scheme to time series with
coordinates in a Polish space.
  The present study relates a different solution to the challenge. The
algorithm is simple and its verification is fairly transparent. Some extensions
to regression, pattern recognition, and on-line forecasting are mentioned.


title: Fast computation of Lyot-style coronagraph propagation

abstract:
  We present a new method for numerical propagation through Lyot-style
coronagraphs using finite occulting masks. Standard methods for coronagraphic
simulations involve Fast Fourier Transforms (FFT) of very large arrays, and
computing power is an issue for the design and tolerancing of coronagraphs on
segmented Extremely Large Telescopes (ELT) in order to handle both the speed
and memory requirements. Our method combines a semi-analytical approach with
non-FFT based Fourier transform algorithms. It enables both fast and
memory-efficient computations without introducing any additional
approximations. Typical speed improvements based on computation costs are of
about ten to fifty for propagations from pupil to Lyot plane, with thirty to
sixty times less memory needed. Our method makes it possible to perform
numerical coronagraphic studies even in the case of ELTs using a contemporary
commercial laptop computer, or any standard commercial workstation computer.


title: Some considerations of finite dimensional spin glasses

abstract:
  In talk I will review the theoretical results that have been obtained for
spin glasses, paying a particular attention to finite dimensional spin glasses.
I will concentrate my attention on the formulation of the mean field approach
and on its numerical and experimental verifications. I will mainly considered
equilibrium properties at zero magnetic field, where the situation is clear and
it should be not controversial. I will present the various hypothesis at the
basis of the theory and I will discuss their physical status.


title:
Model-independent determination of the cosmic expansion rate. I.
  Application to type-Ia supernovae

abstract:
  Aims: In view of the substantial uncertainties regarding the possible
dynamics of the dark energy, we aim at constraining the expansion rate of the
universe without reference to a specific Friedmann model and its parameters.
Methods: We show that cosmological observables integrating over the cosmic
expansion rate can be converted into a Volterra integral equation which is
known to have a unique solution in terms of a Neumann series. Expanding
observables such as the luminosity distances to type-Ia supernovae into a
series of orthonormal functions, the integral equation can be solved and the
cosmic expansion rate recovered within the limits allowed by the accuracy of
the data. Results: We demonstrate the performance of the method applying it to
synthetic data sets of increasing complexity, and to the first-year SNLS data.
In particular, we show that the method is capable of reproducing a hypothetical
expansion function containing a sudden transition.


title: Noncommutative fields and actions of twisted Poincare algebra

abstract:
  Within the context of the twisted Poincar\'e algebra, there exists no
noncommutative analogue of the Minkowski space interpreted as the homogeneous
space of the Poincar\'e group quotiented by the Lorentz group. The usual
definition of commutative classical fields as sections of associated vector
bundles on the homogeneous space does not generalise to the noncommutative
setting, and the twisted Poincar\'e algebra does not act on noncommutative
fields in a canonical way. We make a tentative proposal for the definition of
noncommutative classical fields of any spin over the Moyal space, which has the
desired representation theoretical properties. We also suggest a way to search
for noncommutative Minkowski spaces suitable for studying noncommutative field
theory with deformed Poincar\'e symmetries.


title: Mixing Least-Squares Estimators when the Variance is Unknown

abstract:
  We propose a procedure to handle the problem of Gaussian regression when the
variance is unknown. We mix least-squares estimators from various models
according to a procedure inspired by that of Leung and Barron (2007). We show
that in some cases the resulting estimator is a simple shrinkage estimator. We
then apply this procedure in various statistical settings such as linear
regression or adaptive estimation in Besov spaces. Our results provide
non-asymptotic risk bounds for the Euclidean risk of the estimator.


title: Automorphisms in Loop Quantum Gravity

abstract:
  We investigate a certain distributional extension of the group of spatial
diffeomorphisms in Loop Quantum Gravity. This extension, which is given by the
automorphisms Aut(P) of the path groupoid P, was proposed by Velhinho and is
inspired by category theory. This group is much larger than the group of
piecewise analytic diffeomorphisms. In particular, we will show that graphs
with the same combinatorics but different generalized knotting classes can be
mapped into each other. We describe the automorphism-invariant Hilbert space
and comment on how a combinatorial formulation of LQG might arise.


title:
Directed motion generated by heat bath nonlinearly driven by external
  noise

abstract:
  Based on the system heat bath approach where the bath is nonlinearly
modulated by an external Gaussian random force, we propose a new microscopic
model to study directed motion in the overdamped limit for a nonequilibrium
open system. Making use of the coupling between the heat bath and the external
modulation as a small perturbation we construct a Langevin equation with
multiplicative noise and space dependent dissipation and the corresponding
Fokker-Planck-Smoluchowski equation in the overdamped limit. We examine the
thermodynamic consistency condition and explore the possibility of observing a
phase induced current as a consequence of state dependent diffusion and,
necessarily, nonlinear driving of the heat bath by the external noise.


title:
Dynamics of Vortex Formation in Merging Bose-Einstein Condensate
  Fragments

abstract:
  We study the formation of vortices in a Bose-Einstein condensate (BEC) that
has been prepared by allowing isolated and independent condensed fragments to
merge together. We focus on the experimental setup of Scherer {\it et al.}
[Phys. Rev. Lett. {\bf 98}, 110402 (2007)], where three BECs are created in a
magnetic trap that is segmented into three regions by a repulsive optical
potential; the BECs merge together as the optical potential is removed. First,
we study the two-dimensional case, in particular we examine the effects of the
relative phases of the different fragments and the removal rate of the optical
potential on the vortex formation. We find that many vortices are created by
instant removal of the optical potential regardless of relative phases, and
that fewer vortices are created if the intensity of the optical potential is
gradually ramped down and the condensed fragments gradually merge. In all
cases, self-annihilation of vortices of opposite charge is observed. We also
find that for sufficiently long barrier ramp times, the initial relative phases
between the fragments leave a clear imprint on the resulting topological
configuration. Finally, we study the three-dimensional system and the formation
of vortex lines and vortex rings due to the merger of the BEC fragments; our
results illustrate how the relevant vorticity is manifested for appropriate
phase differences, as well as how it may be masked by the planar projections
observed experimentally.


title: Gauge k-vortices

abstract:
  We consider gauge vortices in symmetry breaking models with a non-canonical
kinetic term. This work extends our previous study on global topological
k-defects (hep-th/0608071), including a gauge field. The model consists of a
scalar field with a non-canonical kinetic term, while for the gauge field the
standard form of its kinetic term is preserved. Topological defects arising in
such models, k-vortices, may have quite different properties as compared to
``standard'' vortices. This happens because an additional dimensional parameter
enters the Lagrangian for the considered model -- a ``kinetic'' mass. We
briefly discuss possible consequences for cosmology, in particular, the
formation of cosmic strings during phase transitions in the early universe and
their properties.


title: Geodesible contact structures on 3--manifolds

abstract:
  In this paper, we study and almost completely classify contact structures on
closed 3--manifolds which are totally geodesic for some Riemannian metric. Due
to previously known results, this amounts to classifying contact structures on
Seifert manifolds which are transverse to the fibers. Actually, we obtain the
complete classification of contact structures with negative (maximal) twisting
number (which includes the transverse ones) on Seifert manifolds whose base is
not a sphere, as well as partial results in the spherical case.


title: M31N-2007-06b: A Nova in the M31 Globular Cluster Bol 111

abstract:
  We report spectroscopic observations of the nova M31N-2007-06b, which was
found to be spatially coincident with the M31 globular cluster Bol 111. This
nova is the first out of more than 700 discovered in M31 over the past century
to be associated with one of the galaxy's globular clusters. A total of three
spectra of the nova were obtained 3, 6, and 36 days post discovery. The data
reveal broad (FWHM ~3000 km/s) Balmer, NII, and NIII emission lines, and show
that the nova belongs to the He/N spectroscopic class. The He/N class of novae
are relatively rare, making up roughly 15% of the novae with measured spectra
in M31, and roughly 20-25% of the Galactic novae for which spectroscopic data
are available. The implications of a nova, particularly an He/N nova, occurring
in a globular cluster are discussed.


title:
Time-Domain Measurement of Spontaneous Vibrational Decay of Magnetically
  Trapped NH

abstract:
  The v = 1 -> 0 radiative lifetime of NH (X triplet-Sigma-, v=1,N=0) is
determined to be tau_rad,exp. = 37.0 +/- 0.5 stat +2.0 / -0.8 sys miliseconds,
corresponding to a transition dipole moment of |mu_10| = 0.0540 + 0.0009 /
-0.0018 Debye. To achieve the long observation times necessary for direct
time-domain measurement, vibrationally excited NH (X triplet-Sigma-, v=1,N=0)
radicals are magnetically trapped using helium buffer-gas loading. Simultaneous
trapping and lifetime measurement of both the NH(v=1, N=0) and NH(v=0,N=0)
populations allows for accurate extraction of tau_rad,exp. Background helium
atoms are present during our measurement of tau_rad,exp., and the rate constant
for helium atom induced collisional quenching of NH(v=1,N=0) was determined to
be k_q < 3.9 * 10^-15 cm^3/s. This bound on k_q yields the quoted systematic
uncertainty on tau_rad,exp. Using an ab initio dipole moment function and an
RKR potential, we also determine a theoretical value of 36.99 ms for this
lifetime, in agreement with our experimental value. Our results provide an
independent determination of tau_rad,10, test molecular theory, and furthermore
demonstrate the efficacy of buffer-gas loading and trapping in determining
metastable radiative and collisional lifetimes.


title: Kinematics of NGC 2264: signs of cluster formation

abstract:
  We present results from 1078 high resolution spectra of 990 stars in the
young open cluster NGC 2264, obtained with the Hectochelle multiobject echelle
spectrograph on the 6.5m MMT. We confirm 471 stars as members, based on their
radial velocity and/or H-alpha emission. The radial velocity distribution of
cluster members is non-Gaussian with a dispersion of approx 3.5 km/s. We find a
substantial north-south velocity gradient and spatially coherent structure
inthe radial velocity distribution, similar to that seen in the molecular gas
in the region. Our results suggest that there are at least three
distinguishable subclusters in NGC 2264, correlated with similar structure seen
in 13CO emission, which is likely to be a remnant of initial structure in this
very young cluster. We propose that this substructure is the result of
gravitational amplification of initial inhomogeneities during overall collapse
to a filamentary distribution of gas and stars, as found in simulations by
Burkert & Hartman (2004).


title:
Effects of carbon nanotubes on grain boundary sliding in zirconia
  polycrystals

abstract:
  Mechanical properties of zirconia polycrystals decrease drastically at high
temperature due to thermally activated grain boundary (GB) sliding, leading to
plastic or even super-plastic deformation. As GB sliding is a source of energy
dissipation in the material, mechanical loss measurements are well suited to
study such a mechanism. They reveal, in general, a mechanical loss peak, which
evolves into an exponential increase at higher temperature. When intergranular
glassy films or/and amorphous pockets are presented in polycrystalline
ceramics, the mechanical loss is globally higher and so is the creep rate. Here
we show that introducing carbon nanotubes in zirconia, in particular, reduces
drastically GB sliding and consequently the mechanical loss at high
temperature. The nanotubes were observed at the grain boundaries by
high-resolution transmission electron microscopy and were related to the
reduction of superplasic flow through the boundaries, which should improve the
material creep resistance.


title: An extension of the Linear Delta Expansion to Superspace

abstract:
  We introduce and discuss the method of Linear Delta Expansion for the
calculation of effective potentials in superspace, by adopting the improved
version of the super-Feynman rules. Calculations are carried out up to
two-loops and an expression for the optimized K\"{a}hler potential is worked
out.


title: Lawson homology, morphic cohomology and Chow motives

abstract:
  In this paper, the Lawson homology and morphic cohomology are defined on the
Chow motives. We also define the rational coefficient Lawson homology and
morphic cohomology of the Chow motives of finite quotient projective varieties.
As a consequence, we obtain a formula for the Hilbert scheme of points on a
smooth complex projective surface. Further discussion concerning generic finite
maps is given. As a result, we give examples of self-product of smooth
projective curves with nontrivial Griffiths groups by using a result of Ceresa.


title:
The impact of Spitzer infrared data on stellar mass estimates - and a
  revised galaxy stellar mass function at 0 < z < 5

abstract:
  Aims: We estimate stellar masses of galaxies in the high redshift universe
with the intention of determining the influence of newly available Spitzer/IRAC
infrared data on the analysis. Based on the results, we probe the mass assembly
history of the universe.
  Methods: We use the GOODS-MUSIC catalog, which provides multiband photometry
from the U--filter to the 8 mum Spitzer band for almost 15,000 galaxies with
either spectroscopic (for ~7 % of the sample) or photometric redshifts, and
apply a standard model fitting technique to estimate stellar masses. We then
repeat our calculations with fixed photometric redshifts excluding Spitzer
photometry and directly compare the outcomes to look for systematic deviations.
Finally we use our results to compute stellar mass functions and mass densities
up to redshift z = 5.
  Results: We find that stellar masses tend to be overestimated on average if
further constraining Spitzer data are not included into the analysis. Whilst
this trend is small up to intermediate redshifts z < 2.5 and falls within the
typical error in mass, the deviation increases strongly for higher redshifts
and reaches a maximum of a factor of three at redshift z = 3.5. Thus, up to
intermediate redshifts, results for stellar mass density are in good agreement
with values taken from literature calculated without additional Spitzer
photometry. At higher redshifts, however, we find a systematic trend towards
lower mass densities if Spitzer/IRAC data are included.


title: Geometric Transitions and D-Term SUSY Breaking

abstract:
  We propose a new way of using geometric transitions to study metastable vacua
in string theory and certain confining gauge theories. The gauge theories in
question are N=2 supersymmetric theories deformed to N=1 by superpotential
terms. We first geometrically engineer supersymmetry-breaking vacua by wrapping
D5 branes on rigid 2-cycles in noncompact Calabi-Yau geometries, such that the
central charges of the branes are misaligned. In a limit of slightly misaligned
charges, this has a gauge theory description, where supersymmetry is broken by
Fayet-Iliopoulos D-terms. Geometric transitions relate these configurations to
dual Calabi-Yaus with fluxes, where H_RR, H_NS and dJ are all nonvanishing. We
argue that the dual geometry can be effectively used to study the resulting
non-supersymmetric, confining vacua.


title: Massless Limit of Gravitational Higgs Mechanism

abstract:
  In gravitational Higgs mechanism graviton components acquire mass via
spontaneous diffeomorphism breaking by scalar vacuum expectation values. We
point out that in the massless limit the resulting theory is not
Einstein-Hilbert gravity (EHG) but constrained gravity (CG). Consequently,
massive solutions in the massless limit must be compared to those in CG (as
opposed to EHG). We discuss spherically symmetric solutions in this context.
The Schwarzschild solution in EHG can be coordinate-transformed such that it is
also a solution in CG. The resulting solutions are non-perturbative in the
asymptotic regime, and are reproduced in the massless limit of asymptotic
massive solutions, hence no van Dam-Veltman-Zakharov discontinuity. We point
out that higher curvature terms must be included to obtain non-singular
spherically symmetric massive solutions and discuss a suitable framework.


title: Cascading to the MSSM

abstract:
  The MSSM can arise as an orientifold of a pyramid-like quiver in the context
of intersecting D-branes. Here we consider quiver realizations of the MSSM
which can emerge at the bottom of a duality cascade. We classify all possible
minimal ways this can be done by allowing only one extra node. It turns out
that this requires extending the geometry of the pyramid to an octahedron. The
MSSM at the bottom of the cascade arises in one of two possible ways, with the
extra node disappearing either via Higgsing or confinement. Remarkably, the
quiver of the Higgsing scenario turns out to be nothing but the quiver version
of the left-right symmetric extension of the MSSM. In the minimal confining
scenario the duality cascade can proceed if and only if there is exactly one
up/down Higgs pair. Moreover, the symmetries of the octahedron naturally admit
an automorphism of the quiver which solves a version of the mu problem
precisely when there are an odd number of generations.


title: An elasto-visco-plastic model for immortal foams or emulsions

abstract:
  A variety of complex fluids consist in soft, round objects (foams, emulsions,
assemblies of copolymer micelles or of multilamellar vesicles -- also known as
onions). Their dense packing induces a slight deviation from their prefered
circular or spherical shape. As a frustrated assembly of interacting bodies,
such a material evolves from one conformation to another through a succession
of discrete, topological events driven by finite external forces. As a result,
the material exhibits a finite yield threshold. The individual objects usually
evolve spontaneously (colloidal diffusion, object coalescence, molecular
diffusion), and the material properties under low or vanishing stress may alter
with time, a phenomenon known as aging. We neglect such effects to address the
simpler behaviour of (uncommon) immortal fluids: we construct a minimal, fully
tensorial, rheological model, equivalent to the (scalar) Bingham model.
Importantly, the model consistently describes the ability of such soft
materials to deform substantially in the elastic regime (be it compressible or
not) before they undergo (incompressible) plastic creep -- or viscous flow
under even higher stresses.


title: Spin dependent parton distributions and structure functions

abstract:
  Nuclear parton distributions and structure functions are determined in an
effective chiral quark theory. We also discuss an extension of our model to
fragmentation functions.


title:
On the Asymptotic Representation for Transverse Magnetic Multiple
  Scattering of Radiation by an Infinite Grating of Dielectric Circular
  Cylinders at Oblique Incidence

abstract:
  In this article, we present the derivation of the asymptotic forms of the
equations corresponding to the scattering coefficients of the exterior electric
and magnetic fields of an infinite grating of insulating dielectric circular
cylinders for vertically polarized and obliquely incident plane electromagnetic
waves. Exploiting the generalized forms of the Twersky's elementary function
representations for Schloemilch series, we have deducted an Ansatz describing
the behavior of the scattering coefficients of the electric and magnetic fields
for obliquely incident waves when the grating spacing is much smaller than the
wavelength of the incident electromagnetic radiation. Introducing the statement
of this Ansatz into the equations of the scattering coefficients of the
infinite grating at oblique incidence, and expanding the scattering
coefficients in the form of an asymptotic series as a function of the ratio of
the radius of the cylinders to the grating spacing, we have acquired two new
infinite sets of algebraic equations associated with the scattering
coefficients of the exterior electric and magnetic fields of the grating for
vertically polarized and obliquely incident plane waves.


title: Kinematic Structure of the Orion Nebula Cluster and its Surroundings

abstract:
  We present results from 1351 high resolution spectra of 1215 stars in the
Orion Nebula Cluster (ONC) and the surrounding Orion 1c association, obtained
with the Hectochelle multiobject echelle spectrograph on the 6.5m MMT. We
confirmed 1111 stars as members, based on their radial velocity and/or H-alpha
emission. The radial velocity distribution of members shows a dispersion of 3.1
km/s. We found a substantial north-south velocity gradient and spatially
coherent structure in the radial velocity distribution, similar to that seen in
the molecular gas in the region. We also identified several binary and high
velocity stars, a region exhibiting signs of triggered star formation, and a
possible foreground population of stars somewhat older than the ONC. Stars
without infrared excesses (as detected with the IRAC instrument on the Spitzer
Space Telescope) exhibit a wider spread in radial velocity than the infrared
excess stars; this spread is mostly due to a blue-shifted population of stars
that may constitute a foreground population. We also identify some accreting
stars, based on H-alpha, that do not have detectable infrared excesses with
IRAC, and thus are potential transitional disk systems (objects with inner disk
holes). We propose that the substructure seen both in stellar and gaseous
component is the result of non-uniform gravitational collapse to a filamentary
distribution of gas. The spatial and kinematic correlation between the stellar
and gaseous components suggests the region is very young, probably only ~1
crossing time old or less to avoid shock dissipation and gravitational
interactions which would tend to destroy the correlation between stars and gas.


title: Polarized structure functions of nucleons and nuclei

abstract:
  We determine the quark distributions and structure functions for both
unpolarized and polarized DIS of leptons on nucleons and nuclei. The scalar and
vector mean fields in the nucleus modify the motion of the quarks inside the
nucleons. By taking into account this medium modification, we are able to
reproduce the experimental data on the unpolarized EMC effect, and to make
predictions for the polarized EMC effect. We discuss examples of nuclei where
the polarized EMC effect could be measured. We finally present an extension of
our model to describe fragmentation functions.


title: Uniform non-amenability, cost, and the first l^2-Betti number

abstract:
  It is shown that $2\beta_1(\G)\leq h(\G)$ for any countable group $\G$, where
$\beta_1(\G)$ is the first $\ell^2$-Betti number and $h(\G)$ the uniform
isoperimetric constant. In particular, a countable group with non-vanishing
first $\ell^2$-Betti number is uniformly non-amenable.
  We then define isoperimetric constants in the framework of measured
equivalence relations. For an ergodic measured equivalence relation $R$ of type
$\IIi$, the uniform isoperimetric constant $h(R)$ of $R$ is invariant under
orbit equivalence and satisfies $$ 2\beta_1(R)\leq 2C(R)-2\leq h(R), $$ where
$\beta_1(\R)$ is the first $\ell^2$-Betti number and $C(R)$ the cost of $R$ in
the sense of Levitt (in particular $h(R)$ is a non-trivial invariant). In
contrast with the group case, uniformly non-amenable measured equivalence
relations of type $\IIi$ always contain non-amenable subtreeings.
  An ergodic version $h_e(\G)$ of the uniform isoperimetric constant $h(\G)$ is
defined as the infimum over all essentially free ergodic and measure preserving
actions $\alpha$ of $\G$ of the uniform isoperimetric constant $h(\R_\alpha)$
of the equivalence relation $R_\alpha$ associated to $\alpha$. By establishing
a connection with the cost of measure-preserving equivalence relations, we
prove that $h_e(\G)=0$ for any lattice $\G$ in a semi-simple Lie group of real
rank at least 2 (while $h_e(\G)$ does not vanish in general).


title:
Electronic Transport through Magnetic Molecules with Soft Vibrating
  Modes

abstract:
  The low-temperature transport properties of a molecule are studied in the
field-effect transitor geometry. The molecule has an internal mechanical mode
that modulates its electronic levels and renormalizes both the interactions and
the coupling to the electrodes. For a soft mechanical mode the spin
fluctuations in the molecule are dominated by the bare couplings while the
valence changes are determined by the dressed energies. In this case, the
transport properties present an anomalous behavior and the Kondo temperature
has a weak gate voltage dependence. These observations are in agreement with
recent experimental data.


title: Chandra Observations of Early-type Galaxies

abstract:
  We have performed uniform analysis of a sample of 54 nearby, early-type
galaxies observed with \emph{Chandra}. In this work we present the spectral
results for both the diffuse Interstellar Medium, ISM, and low-mass X-ray
binaries, LMXBs. We determine the metallicity of the hot ISM in the 22
brightest galaxies and find a narrow range of abundance ratios relative to
iron. The average iron metallicity of these bright galaxies is $0.96\pm0.33$
relative to solar. By assuming these enrichment patterns continue to fainter
galaxies, we are able to extend accurate ISM modeling down to the faintest
galaxies in the sample. The sample of galaxies span 4.5 orders of magnitude in
X-ray luminosity starting at $L_X=10^{38} erg \cdot s^{-1}$ and the average gas
temperature in the sample is $0.58\pm0.24 keV$. We present the X-ray properties
of these galaxies scaled to one effective radius as well as radial variations
of gas and stellar binary luminosities, and radial variations of gas
temperature, metallicity, mass, entropy and density.


title: Realistic Yukawa Textures and SUSY Spectra from Intersecting Branes

abstract:
  We study the possible phenomenology of a three-family Pati-Salam model
constructed from intersecting D6-branes in Type IIA string theory on the
T^6/(Z2 x Z2) orientifold with some desirable semi-realistic features. In the
model, tree-level gauge coupling unification is achieved automatically at the
string scale, and the gauge symmetry may be broken to the Standard Model (SM)
close to the string scale. The small number of extra chiral exotic states in
the model may be decoupled via the Higgs mechanism and strong dynamics. We
calculate the possible supersymmetry breaking soft terms and the corresponding
low-energy supersymmetric particle spectra which may potentially be tested at
the Large Hadron Collider (LHC). We find that for the viable regions of the
parameter space the lightest CP-even Higgs boson mass usually satisfies m_H <
120 GeV, and the observed dark matter density may be generated. Finally, we
find that it is possible to obtain correct SM quark masses and mixings, and the
tau lepton mass at the unification scale. Additionally, neutrino masses and
mixings may be generated via the seesaw mechanism. Mechanisms to stabilize the
open and closed-string moduli, which are necessary for the model to be truly
viable and to make definite predictions are discussed.


title:
Coherent, adiabatic and dissociation regimes in coupled atomic-molecular
  Bose-Einstein condensates

abstract:
  We discuss the dynamics of a Bose-Einstein condensate of atoms which is
suddenly coupled to a condensate of molecules by an optical or magnetic
Feshbach resonance. Three limiting regimes are found and can be understood from
the transient dynamics occuring for each pair of atoms. This transient dynamics
can be summarised into a time-dependent shift and broadening of the molecular
state. A simple Gross-Pitaevskii picture including this shift and broadening is
proposed to describe the system in the three regimes. Finally, we suggest how
to explore these regimes experimentally.


title:
Redox Entropy of Plastocyanin: Developing a Microscopic View of
  Mesoscopic Polar Solvation

abstract:
  We report applications of analytical formalisms and Molecular Dynamics (MD)
simulations to the calculation of redox entropy of plastocyanin metalloprotein
in aqueous solution. The goal of our analysis is to establish critical
components of the theory required to describe polar solvation at the mesoscopic
scale. The analytical techniques include a microscopic formalism based on
structure factors of the solvent dipolar orientations and density and continuum
dielectric theories. The microscopic theory employs the atomistic structure of
the protein with force-field atomic charges and solvent structure factors
obtained from separate MD simulations of the homogeneous solvent. The MD
simulations provide linear response solvation free energies and reorganization
energies of electron transfer in the temperature range 280--310 K. We found
that continuum models universally underestimate solvation entropies, and a more
favorable agreement is reported between the microscopic calculations and MD
simulations. The analysis of simulations also suggests that difficulties of
extending standard formalisms to protein solvation are related to the
inhomogeneous structure of the solvation shell at the protein-water interface
combining islands of highly structured water around ionized residues along with
partial dewetting of hydrophobic patches. Quantitative theories of
electrostatic protein hydration need to incorporate realistic density profile
of water at the protein-water interface.


title: Slow failure of quasi-brittle solids

abstract:
  A new mesoscopic non-equilibrium thermodynamic approach is developed. The
approach is based on the thermodynamic identity associated the first and second
law of thermodynamics. In the framework of the approach different internal
dissipative channels of energy are taken in account in an explicit form,
namely, the thermal channel and channels of defect subsystems. The identity has
a perfect differential form what permits to introduce an extended
non-equilibrium state and use the good developed mathematical formalism of
equilibrium and non-equilibrium thermodynamics. The evolution of
non-equilibrium variables of a physical system are described by a Landau-based
equation set expressed through internal or different kinds of free energy
connected by means of the Legendre transforms. The accordance between the
different kinds of energy is possible owing to introduction of some trends into
the equation subset described the defect subsystems and having a nature of
structural viscosity. The possibilities of the approach are illustrated on the
example of quasibrittle solid damage and failure. Taking into account only one
type of defects (viz., microcracks) and mechanical parameters in an expansion
of free energy down to third powers in relative to average energy per
microcrack, the description of destruction of quasi-brittle solids during
long-term loading is considered. The consideration allows to find equilibrium
and non-equilibrium values of the free energy. A qualitative behavior of the
system on parameters of the theory is analyzed. The destruction of material is
described from the uniform positions, both at uniform tension and uniaxial
compression. Origins of the high stability of mine workings at small depths and
their instability at large depths are explained.


title: Infinite-Dimensional Symmetries of Two-Dimensional Coset Models

abstract:
  It has long been appreciated that the toroidal reduction of any gravity or
supergravity to two dimensions gives rise to a scalar coset theory exhibiting
an infinite-dimensional global symmetry. This symmetry is an extension of the
finite-dimensional symmetry G in three dimensions, after performing a further
circle reduction. There has not been universal agreement as to exactly what the
extended symmetry algebra is, with different arguments seemingly concluding
either that it is $\hat G$, the affine Kac-Moody extension of G, or else a
subalgebra thereof. Exceptional in the literature for its explicit and
transparent exposition is the extremely lucid discussion by Schwarz, which we
take as our starting point for studying the simpler situation of
two-dimensional flat-space sigma models, which nonetheless capture all the
essential details. We arrive at the conclusion that the full symmetry is
described by the Kac-Moody algebra G, although truncations to subalgebras, such
as the one obtained by Schwarz, can be considered too. We then consider the
explicit example of the SL(2,R)/O(2) coset, and relate Schwarz's approach to an
earlier discussion that goes back to the work of Geroch.


title:
Rabi flopping between ground and Rydberg states with dipole-dipole
  atomic interactions

abstract:
  We demonstrate Rabi flopping of small numbers of $\rm{^{87}Rb}$ atoms between
ground and Rydberg states with $n\le 43$. Coherent population oscillations are
observed for single atom flopping, while the presence of two or more atoms
decoheres the oscillations. We show that these observations are consistent with
van der Waals interactions of Rydberg atoms.


title: Vortex core size in interacting cylindrical nanodot arrays

abstract:
  The effect of dipolar interactions among cylindrical nanodots, with a
vortex-core magnetic configuration, is analyzed by means of analytical
calculations. The cylinders are placed in a N x N square array in two
configurations - core oriented parallel to each other and with antiparallel
alignment between nearest neighbors. Results comprise the variation in the core
radius with the number of interacting dots, the distance between them and dot
height. The dipolar interdot coupling leads to a decrease (increase) of the
core radius for parallel (antiparallel) arrays.


title: Hyperbolic conservation laws and spacetimes with limited regularity

abstract:
  Hyperbolic conservation laws posed on manifolds arise in many applications to
geophysical flows and general relativity. Recent work by the author and his
collaborators attempts to set the foundations for a study of weak solutions
defined on Riemannian or Lorentzian manifolds and includes an investigation of
the existence and qualitative behavior of solutions. The metric on the manifold
may either be fixed (shallow water equations on the sphere, for instance) or be
one of the unknowns of the theory (Einstein-Euler equations of general
relativity).


title:
Generalizations of Nonlinear and Supersymmetric Classical
  Electrodynamics

abstract:
  We first write down a very general description of nonlinear classical
electrodynamics, making use of generalized constitutive equations and
constitutive tensors. Our approach includes non-Lagrangian as well as
Lagrangian theories, allows for electromagnetic fields in the widest possible
variety of media (anisotropic, piroelectric, chiral and ferromagnetic), and
accommodates the incorporation of nonlocal effects. We formulate
electric-magnetic duality in terms of the constitutive tensors. We then propose
a supersymmetric version of the general constitutive equations, in a superfield
approach.

categories: hep-th hep-ph math-ph math.MP physics.class-ph


title:
Spin-torque driven ferromagnetic resonance of Co/Ni synthetic layers in
  spin valves

abstract:
  Spin-torque driven ferromagnetic resonance (ST-FMR) is used to study thin
Co/Ni synthetic layers with perpendicular anisotropy confined in spin-valve
based nanojunctions. Field swept ST-FMR measurements were conducted with a
magnetic field applied perpendicular to the layer surface. The resonance lines
were measured under low amplitude rf excitation, from 1 to 20 GHz. These
results are compared with those obtained using conventional rf field driven FMR
on extended films with the same Co/Ni layer structure. The layers confined in
spin valves have a lower resonance field, a narrower resonance linewidth and
approximately the same linewidth vs frequency slope, implying the same damping
parameter. The critical current for magnetic excitations is determined from
measurements of the resonance linewidth vs dc current and is in accord with the
one determined from I-V measurements.


title:
Generalized monotone schemes, discrete paths of extrema, and discrete
  entropy conditions

abstract:
  Solutions to conservation laws satisfy the monotonicity property: the number
of local extrema is a non-increasing function of time, and local
maximum/minimum values decrease/increase monotonically in time. This paper
investigates this property from a numerical standpoint. We introduce a class of
fully discrete in space and time, high order accurate, difference schemes,
called generalized monotone schemes. Convergence toward the entropy solution is
proven via a new technique of proof, assuming that the initial data has a
finite number of extremum values only, and the flux-function is strictly
convex. We define discrete paths of extrema by tracking local extremum values
in the approximate solution. In the course of the analysis we establish the
pointwise convergence of the trace of the solution along a path of extremum. As
a corollary, we obtain a proof of convergence for a MUSCL-type scheme being
second order accurate away from sonic points and extrema.


title: On holographic phase transitions at finite chemical potential

abstract:
  Recent Holographic studies have shown that N=4 super Yang-Mills theory
coupled to fundamental matter with finite chemical potential undergoes a first
order phase transition. In this paper, we study Nf D6 probe branes with or
without electric field on it in the black D4 brane background compactified on a
circle with supersymmetry breaking boundary condition. At energy scales much
lower than the compactification scale, the dual gauge theory is effectively
four dimensional non-supersymmetric SU(Nc) Yang-Mills theory coupled to
fundamental matter with or without baryon number charge. Within the
supergravity approximation, the decoupling of the Kaluza-Klein modes is not
fully realized. For chemical potential mu<NcMq there is a line of first order
phase transitions from stable meson phase to unstable meson phase. On the other
hand for mu>NcMq there is no phase transition and mesons are unstable. A
peculiar and interesting property of this system is that for a certain range of
chemical potential mu<NcMq, a new phase transition appears in the unstable
meson phase. This phase transition is characterized by a discontinuous change
of unstable meson lifetime.


title:
Hinode observations reveal boundary layers of magnetic elements in the
  solar photosphere

abstract:
  We study the structure of the magnetic elements in network-cell interiors. A
quiet Sun area close to the disc centre was observed with the
spectro-polarimeter of the Solar Optical Telescope on board the Hinode space
mission, which yielded the best spatial resolution ever achieved in
polarimetric data of the Fe I 630 nm line pair. For comparison and
interpretation, we synthesize a similar data set from a three-dimensional
magneto-hydrodynamic simulation. We find several examples of magnetic elements,
either roundish (tube) or elongated (sheet), which show a central area of
negative Stokes-V area asymmetry framed or surrounded by a peripheral area with
larger positive asymmetry. This pattern was predicted some eight years ago on
the basis of numerical simulations. Here, we observationally confirm its
existence for the first time. We gather convincing evidence that this pattern
of Stokes-V area asymmetry is caused by the funnel-shaped boundary of magnetic
elements that separates the flux concentration from the weak-field environment.
We also conclude that this kind of magnetic element of the internetwork is
accompanied by electric current sheets.


title:
Dynamic Moment Analysis of the Extracellular Electric Field of a
  Biologically Realistic Spiking Neuron

abstract:
  Based upon the membrane currents generated by an action potential in a
biologically realistic model of a pyramidal, hippocampal cell within rat CA1,
we perform a moment expansion of the extracellular field potential. We
decompose the potential into both inverse and classical moments and show that
this method is a rapid and efficient way to calculate the extracellular field
both near and far from the cell body. The action potential gives rise to a
large quadrupole moment that contributes to the extracellular field up to
distances of almost 1 cm. This method will serve as a starting point in
connecting the microscopic generation of electric fields at the level of
neurons to macroscopic observables such as the local field potential.


title: Heat kernels and critical limits

abstract:
  This paper is an exposition of several questions linking heat kernel measures
on infinite dimensional Lie groups, limits associated with critical Sobolev
exponents, and Feynmann-Kac measures for sigma models.


title: Conservation laws with vanishing nonlinear diffusion and dispersion

abstract:
  We study the limiting behavior of the solutions to a class of conservation
laws with vanishing nonlinear diffusion and dispersion terms. We prove the
convergence to the entropy solution of the first order problem under a
condition on the relative size of the diffusion and the dispersion terms. This
work is motivated by the pseudo-viscosity approximation introduced by Von
Neumann in the 50's.


title: 3D Spectroscopy in the Virtual Observatory: Current Status

abstract:
  Three cornerstones for the 3D data support in the Virtual Observatory are:
(1) data model to describe them, (2) data access services providing access to
fully-reduced datasets, and (3) client applications which can deal with 3D
data. Presently all these components became available in the VO. We demonstrate
an application of the IVOA Characterisation data model to description of IFU
and Fabry-Perot datasets. Two services providing SSA-like access to 3D-spectral
data and Characterisation metadata have been implemented by us: ASPID-SR at SAO
RAS for accessing IFU and Fabry-Perot data from the Russian 6-m telescope, and
the Giraffe Archive at the VO Paris portal for the VLT FLAMES-Giraffe datasets.
We have implemented VO Paris Euro3D Client, handling Euro3D FITS format, that
interacts with CDS Aladin and ESA VOSpec using PLASTIC to display spatial and
spectral cutouts of 3D datasets. Though the prototype we are presenting is yet
rather simple, it demonstrates how 3D spectroscopic data can be fully
integrated into the VO infrastructure.


title: Non-inertial effects in fusion reactions of astrophysical interest

abstract:
  We discuss the effects of non-inertial motion in reactions occurring in
laboratory, stars, and elsewhere. It is demonstrated that non-inertial effects
due to large accelerations during nuclear collisions might have appreciable
effects nuclear and atomic transitions. We also explore the magnitude of the
corrections induced by strong gravitational fields on nuclear reactions in
massive, compact stars, and the neighborhood of black holes.


title: Polarization Measurements and the Pairing Gap in the Universal Regime

abstract:
  We analyze recent cold-atom experiments on imbalanced Fermi systems using a
minimal model with a BCS-like superfluid phase coexisting with a normal phase.
This model is used to extract the T=0 pairing gap in the fully paired
superfluid state. The recently measured particle density profiles are in good
agreement with the theoretical predictions obtained from the universal
parameters from previous Quantum Monte Carlo calculations. We find that the T=0
pairing gap is greater than 0.4 times the Fermi energy $E_F$, with a preferred
value of $0.45 \pm 0.05$ $E_F$. The ratio of the pairing gap $\Delta$ to the
Fermi Energy $E_F$ is larger here than in any other system of strongly-paired
fermions in which individual pairs are unbound.


title: Twists of genus three Jacobians

abstract:
  We give a criterion to distinguish between a genus three Jacobian and its
[-1] twist in terms of the product of the 36 even theta nulls.
  We also express the product of the 36 theta nulls in terms of the
discriminant of a genus three curve.
  The results are arithmetic in nature and thus add to previous work over C on
the product of the even theta nulls. They generalize previous work of
Ritzenthaler and Lachaud for Abelian threefolds which are (2,2,2) isogenous to
a product of elliptic curves.
  This answers a 2003 of letter of Jean-Pierre Serre to Jaap Top.


title: Minimal Direct Gauge Mediation

abstract:
  We propose a simple model of gauge mediation where supersymmetry is broken by
a strong dynamics at O(100)TeV.


title: Spaces and groups with conformal dimension greater than one

abstract:
  We show that if a complete, doubling metric space is annularly linearly
connected then its conformal dimension is greater than one, quantitatively. As
a consequence, we answer a question of Bonk and Kleiner: if the boundary of a
one-ended hyperbolic group has no local cut points, then its conformal
dimension is greater than one.


title:
Unstable Disk Accretion to Magnetized Stars: First Global 3D MHD
  Simulations

abstract:
  We report on the first global three-dimensional (3D) MHD simulations of disk
accretion onto a rotating magnetized star through the Rayleigh-Taylor
instability. The star has a dipole field misaligned relative to the rotation
axis by a small angle Theta. Simulations show that, depending on the accretion
rate, a star may be in the stable or unstable regime of accretion. In the
unstable regime, matter penetrates deep into the magnetosphere through several
elongated "tongues" which deposit matter at random places on the surface of the
star, leading to stochastic light-curves. In the stable regime, matter accretes
in ordered funnel streams and the light-curves are almost periodic. A star may
switch between these two regimes depending on the accretion rate and may thus
show alternate episodes of ordered pulsations and stochastic light-curves. In
the intermediate regime, both stochastic and ordered pulsations are observed.
For Theta > 30 degrees, the instability is suppressed and stable accretion
through funnel streams dominates.


title: The Kagome Antiferromagnet: A Schwinger-Boson Mean-Field Theory Study

abstract:
  The Heisenberg antiferromagnet on the Kagom\'{e} lattice is studied in the
framework of Schwinger-boson mean-field theory. Two solutions with different
symmetries are presented. One solution gives a conventional quantum state with
$\mathbf{q}=0$ order for all spin values. Another gives a gapped spin liquid
state for spin $S=1/2$ and a mixed state with both $\mathbf{q}=0$ and
$\sqrt{3}\times \sqrt{3}$ orders for spin $S>1/2$. We emphasize that the mixed
state exhibits two sets of peaks in the static spin structure factor. And for
the case of spin $S=1/2$, the gap value we obtained is consistent with the
previous numerical calculations by other means. We also discuss the
thermodynamic quantities such as the specific heat and magnetic susceptibility
at low temperatures and show that our result is in a good agreement with the
Mermin-Wagner theorem.


title: A coupled Volterra system and its exact solutions

abstract:
  A coupled Volterra system is proposed. The model can be considered as one of
the integrable discrete form of the coupled integrable KdV system which is a
significant physical model. Many types of cnoidal waves, positons, negatons
(solitons) and complexitons of the model are obtained by a simple rational
expansion method of the Jacobi elliptic functions, trigonometric functions and
hyperbolic functions.


title:
Strings in pp-wave background and background B-field from membrane and
  its symplectic quantization

abstract:
  The symplectic quantization technique is applied to open free membrane and
strings in pp-wave background and background gauge field obtained by
compactifying the open membrane in the presence of a background anti-symmetric
3--form field. In both cases, first the Poisson brackets among the Fourier
modes are obtained and then the Poisson brackets among the membrane(string)
coordinates are computed. The full noncommutative phase-space structure is
reproduced in case of strings in pp-wave background and background gauge field.
We feel that this method of obtaining the Poisson algebra is more elegant than
previous approaches discussed in the literature.


title: Radiative Transfer and Limb Darkening of Accretion Disks

abstract:
  Transfer equation in a geometrically thin accretion disk is reexamined under
the plane-parallel approximation with finite optical depth. Emergent intensity
is analytically obtained in the cases with or without internal heating. For
large or infinite optical depth, the emergent intensity exhibits a usual
limb-darkening effect, where the intensity linearly changes as a function of
the direction cosine. For small optical depth, on the other hand, the
angle-dependence of the emergent intensity drastically changes. In the case
without heating but with uniform incident radiation at the disk equator, the
emergent intensity becomes isotropic for small optical depth. In the case with
uniform internal heating, the limb brightening takes place for small optical
depth. We also emphasize and discuss the limb-darkening effect in an accretion
disk for several cases.


title: Relativistic Radiative Flow in a Luminous Disk II

abstract:
  Radiatively-driven transfer flow perpendicular to a luminous disk is examined
in the relativistic regime of $(v/c)^2$, taking into account the gravity of the
central object. The flow is assumed to be vertical, and the gas pressure as
well as the magnetic field are ignored. Using a velocity-dependent variable
Eddington factor, we can solve the rigorous equations of the relativistic
radiative flow accelerated up to the {\it relativistic} speed. For sufficiently
luminous cases, the flow resembles the case without gravity. For less-luminous
or small initial radius cases, however, the flow velocity decreases due to
gravity. Application to a supercritical accretion disk with mass loss is
briefly discussed.


title: Radiative Transfer in Accretion-Disk Winds

abstract:
  Radiative transfer equation in an accretion disk wind is examined
analytically and numerically under the plane-parallel approximation in the
subrelativistic regime of $(v/c)^1$, where $v$ is the wind vertical velocity.
Emergent intensity is analytically obtained for the case of a large optical
depth, where the flow speed and the source function are almost constant. The
usual limb-darkening effect, which depends on the direction cosine at the
zero-optical depth surface, does not appear, since the source function is
constant. Because of the vertical motion of winds, however, the emergent
intensity exhibits the {\it velocity-dependent} limb-darkening effect, which
comes from the Doppler and aberration effects. Radiative moments and emergent
intensity are also numerically obtained. When the flow speed is small ($v \leq
0.1c$), the radiative structure resembles to that of the static atmosphere,
where the source function is proportional to the optical depth, and the usual
limb-darkening effect exists. When the flow speed becomes large, on the other
hand, the flow speed attains the constant terminal one, and the
velocity-dependent limb-darkening effect appears. We thus carefully treat and
estimate the wind luminosity and limb-darkening effect, when we observe an
accretion disk wind.