title: A Magnetohydrodynamic Boost for Relativistic Jets

abstract:
  We performed relativistic magnetohydrodynamic simulations of the hydrodynamic
boosting mechanism for relativistic jets explored by Aloy & Rezzolla (2006)
using the RAISHIN code. Simulation results show that the presence of a magnetic
field changes the properties of the shock interface between the tenuous,
overpressured jet ($V^z_j$) flowing tangentially to a dense external medium.
Magnetic fields can lead to more efficient acceleration of the jet, in
comparison to the pure-hydrodynamic case. A ``poloidal'' magnetic field
($B^z$), tangent to the interface and parallel to the jet flow, produces both a
stronger outward moving shock and a stronger inward moving rarefaction wave.
This leads to a large velocity component normal to the interface in addition to
acceleration tangent to the interface, and the jet is thus accelerated to
larger Lorentz factors than those obtained in the pure-hydrodynamic case.
Likewise, a strong ``toroidal'' magnetic field ($B^y$), tangent to the
interface but perpendicular to the jet flow, also leads to stronger
acceleration tangent to the shock interface relative to the pure-hydrodynamic
case. Overall, the acceleration efficiency in the ``poloidal'' case is less
than that of the ``toroidal'' case but both geometries still result in higher
Lorentz factors than the pure-hydrodynamic case. Thus, the presence and
relative orientation of a magnetic field in relativistic jets can significant
modify the hydrodynamic boost mechanism studied by Aloy & Rezzolla (2006).


title: Localized Lna Cooling in Vacuum

abstract:
  In the Square Kilometre Array (SKA) telescope [1], [2], the noise temperature
of the first LNA must be reduced in order to reduce the necessary active area
and the total system costs. Cooling the LNA locally would significantly
decrease the noise figure but also the necessary power since not the whole
system has to be cooled. For optimal thermal isolation, an LNA chip which only
needs 6 bondwires has been chosen, 4 Ground and 2 signal wires. Biasing occurs
on-chip. If the bondwires are 1.5mm long, the total heat conduction of the 6
bondwires is 31 mW, which is added to the power consumption of the LNA (30 mW).
With a power of 61 mW to cool, the Peltier element can achieve a -T of 60K.
With this system, a noise reduction of 30% has been measured with 0.5W of
electrical power. For 15% noise reduction, only 35mW of electrical power was
needed.


title:
UV and optical emission lines from the z=2.6 radio galaxy 0828+193:
  spatially resolved measurements

abstract:
  We present an investigation into the spatial variation of the rest-frame UV
and optical line and continuum emission along the radio axis of the z=2.6 radio
galaxy 0828+193, using long-slit spectra from the Keck II and Subaru
telescopes. Line brightnesses, line ratios and electron temperatures are
examined, and their relationship with the arm-length asymmetry of the radio
source is also investigated. We find that on the side of the nucleus with the
shortest radio lobe, the gas covering factor is higher, and the ionization
parameter is lower. The contrasts in environmental density required to explain
the asymmetries in the line brightness and the radio arm-length asymmetries are
in fair agreement with each other. These results add further weight to the
conclusion of McCarthy, van Breugel & Kapahi (1991) - lobe distance asymmetries
in powerful radio sources are the result of an asymmetry in the environmental
density.
  We also note that the brightness of both the UV and optical continuum
emission shows a similar spatial asymmetry to that shown by the line emission.
While the UV continuum asymmetry can be wholly explained by the expected
asymmetry in the nebular continuum, the optical continuum asymmetry cannot. We
argue that, at least at optical wavelengths, the starlight and/or the scattered
light must also be strongly spatially asymmetric.


title: Optimised Curing of Silver Ink Jet Based Printed Traces

abstract:
  Manufacturing electronic devices by printing techniques with low temperature
sintering of nano-size material particles can revolutionize the electronics
industry in coming years. The impact of this change to the industry can be
significant enabling low-cost products and flexibility in manufacturing.
implementation of a new production technology with new materials requires
thorough elementary knowledge creation. It should be noticed that although some
of first electronic devices ideally can be manufactured by printing, at the
present several modules are in fact manufactured by using hybrid techniques
(for instance photolithography, vapor depositions, spraying, etc...).


title:
A fluctuation-response relation of many Brownian particles under
  non-equilibrium conditions

abstract:
  We study many interacting Brownian particles under a tilted periodic
potential. We numerically measure the linear response coefficient of the
density field by applying a slowly varying potential transversal to the tilted
direction. In equilibrium cases, the linear response coefficient is related to
the intensity of density fluctuations in a universal manner, which is called a
fluctuation-response relation. We then report numerical evidence that this
relation holds even in non-equilibrium cases. This result suggests that
Einstein's formula on density fluctuations can be extended to driven diffusive
systems when the slowly varying potential is applied in a direction transversal
to the driving force.


title: A summary of the beatwave experiments at Ecole Polytechnique

abstract:
  We present a summary of the beatwave particle acceleration program developed
at Ecole Polytechnique. In dedicated experiments, plasma formation, plasma wave
generation and saturation, and particle acceleration were successively studied
and understood in detail. A maximum energy gain of 1.3 MeV was obtained, which
is compatible with an accelerating gradient of 0.7 GV/m.


title:
Measurements of Thermophysical Property of Thin Films by Light Pulse
  Heating Thermoreflectance Methods

abstract:
  Thermoreflectance methods by picosecond pulse heating and by nanosecond pulse
heating have been developed under the same geometrical configuration as the
laser flash method by the National Metrology Institute of JAPAN, AIST. Using
these light pulse heating methods, thermal diffusivity of each layer of
multilayered thin films and boundary thermal resistance between the layers can
be determined from the observed transient temperature curves based on the
response function method. The measurement results of various thin films as
transparent conductive films used for flat panel displays, hard coating films
and multilayered films of the next generation phase-change optical disk will be
presented.


title: Cluster Dynamics Modeling of Materials: Advantages and Limitations

abstract:
  The aim of this paper is to give a short review on cluster dynamics modeling
in the field of atoms and point defects clustering in materials. It is shown
that this method, due to its low computer cost, can handle long term evolution
that cannot, in many cases, be obtained by Lattice Kinetic Monte Carlo methods.
Indeed, such a possibility is achieved thanks to an important drawback that is
the loss of space correlations of the elements of the microstructures. Some
examples, in the field of precipitation and irradiation of metallic materials
are given. The limitations and difficulties of this method are also discussed.
Unsurprisingly, it is shown that it goes in a very satisfactory way when the
objects are distributed homogeneously. Conversely, the source term describing
the primary damage under irradiation, by nature heterogeneous in space and
time, is tricky to introduce especially when displacement cascades are
produced.


title: Discovery of Gas Accretion Onto Stars in 13 Myr old h and chi Persei

abstract:
  We report the discovery of accretion disks associated with ~ 13 Myr-old
intermediate/low-mass stars in h and chi Persei. Optical spectroscopy of ~ 5000
stars in these clusters and a surrounding halo population reveal 32 A-K stars
with H(alpha) emission. Matching these stars with 2MASS and optical photometry
yields 25 stars with the highest probability of cluster membership and
EW(H(alpha)) > 5 angstroms. Sixteen of these sources have EW(H(alpha)) > 10
angstroms. The population of accreting sources is strongly spectral type
dependent: H(alpha) emission characteristic of accretion, especially strong
accretion (EW(H(alpha)) > 10 angstroms), is much more prevalent around stars
later than G0. Strong H(alpha) emission from accretion is typically associated
with redder Ks-[8] colors. The existence of accreting pre-main sequence stars
in h and chi Persei implies that circumstellar gas in some systems, especially
those with primaries later than G5 spectral type, can last longer than 10-15
Myr.


title: CP Violation and Flavour Mixings in Orbifold GUTs

abstract:
  We address the flavour problem by incorporating the hypothesis of universal
strength of Yukawa couplings in the framework of a 5D GUT model compactified on
an $S^1/(Z_2 \times Z_2^{\prime})$ orbifold. We show that a quantitatively
successful picture of fermion masses and mixings emerges from the interplay
between the bulk suppression factors of geometric origin and the phases of the
Yukawa matrices. We give an explicit example, where we obtain a good fit for
both the CKM and PMNS matrices.


title:
Characterization of Thermal Interface Materials to Support Thermal
  Simulation

abstract:
  In this paper new characterization equipment for thermal interface materials
is presented. Thermal management of electronic products relies on the
effec-tive dissipation of heat. This can be achieved by the optimization of the
system design with the help of simulation methods. The precision of these
models relies also on the used material data. For the determi-nation of this
data an experimental set-up for a static measurement is presented, which
evaluates thermal conductivity and interface resistance of thermal inter-face
materials (e.g. adhesive, solder, pads, or pastes). A qualitative
structure-property correlation is pro-posed taking into account particle size,
filler content and void formation at the interface based on high resolution FIB
imaging. The paper gives an overview over the set-up and the measurement
technique and discusses experimental and simulation results.


title: Ultrafast Temperature Profile Calculation in Ic Chips

abstract:
  One of the crucial steps in the design of an integrated circuit is the
minimization of heating and temperature non-uniformity. Current temperature
calculation methods, such as finite element analysis and resistor networks have
considerable computation times, making them incompatible for use in routing and
placement optimization algorithms. In an effort to reduce the computation time,
we have developed a new method, deemed power blurring, for calculating
temperature distributions using a matrix convolution technique in analogy with
image blurring. For steady state analysis, power blurring was able to predict
hot spot temperatures within 1 degree C with computation times 3 orders of
magnitude faster than FEA. For transient analysis the computation times where
enhanced by a factor of 1000 for a single pulse and around 100 for multiple
frequency application, while predicting hot spot temperature within about 1
degree C. The main strength of the power blurring technique is that it exploits
the dominant heat spreading in the silicon substrate and it uses superposition
principle. With one or two finite element simulations, the temperature point
spread function for a sophisticated package can be calculated. Additional
simulations could be used to improve the accuracy of the point spread function
in different locations on the chip. In this calculation, we considered the
dominant heat transfer path through the back of the IC chip and the heat sink.
Heat transfer from the top of the chip through metallization layers and the
board is usually a small fraction of the total heat dissipation and it is
neglected in this analysis.


title:
A Coupled Thermoreflectance Thermography Experimental System and
  Ultra-Fast Adaptive Computational Engine for the Complete Thermal
  Characterization of Three-Dimensional Electronic Devices: Validation

abstract:
  This work builds on the previous introduction [1] of a coupled
experimental-computational system devised to fully characterize the thermal
behavior of complex 3D submicron electronic devices. The new system replaces
the laser-based surface temperature scanning approach with a CCD camera-based
approach. As before, the thermo-reflectance thermography system is used to
non-invasively measure with submicron resolution the 2D surface temperature
field of an activated device. The measured temperature field is then used as
input for an ultra-fast inverse computational solution to fully characterize
the thermal behavior of the complex three-dimensional device. For the purposes
of this investigation, basic micro-heater devices were built, activated, and
measured. In order to quantitatively validate the coupled
experimental-computational system, the system was used to extract geometric
features of a known device, thus assessing the system's ability to combine
measured experimental results and computations to fully characterize complex 3D
electronic devices.


title:
Thermal Transient Multisource Simulation Using Cubic Spline
  Interpolation of Zth Functions

abstract:
  This paper presents a very straightforward method to compute the transient
thermal response to arbitrary power dissipation profiles in electronic devices
with multiple heat sources. Using cubic spline interpolation of simulated or
measured unit power step response curves (Zth-functions), additional errors due
to model reduction can be avoided. No effort has to be spent on the generation
of compact models. The simple analytic form of the interpolating splines can be
exploited to evaluate the convolution integral of the Zth-functions with
arbitrary power profiles at low computational costs. An implementation of the
algorithm in a spreadsheet program (EXCEL) is demonstrated. The results are in
very good agreement with temperature profiles computed by transient Finite
Element simulation but can be obtained in a fraction of the time.


title:
Formation of Moving Magnetic Features and Penumbral Magnetic Fields with
  Hinode/SOT

abstract:
  Vector magnetic fields of moving magnetic features (MMFs) are well observed
with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focus on
the evolution of three MMFs with the SOT in this study. We found that an MMF
having relatively vertical fields with polarity same as the sunspot is detached
from the penumbra around the granules appeared in the outer penumbra. This
suggests that granular motions in the outer penumbra are responsible for the
disintegration of the sunspot. Two MMFs with polarity opposite to the sunspot
are located around the outer edge of horizontal fields extending from the
penumbra. This is an evidence that the MMFs with polarity opposite to the
sunspot are prolongation of penumbral horizontal fields. Radshifts larger than
sonic velocity in the photosphere are detected for some of the MMFs with
polarity opposite to the sunspot.


title:
CCD Thermoreflectance Thermography System: Methodology and Experimental
  Validation

abstract:
  This work introduces a thermoreflectance-based system designed to measure the
surface temperature field of activated microelectronic devices at submicron
spatial resolution with either a laser or a CCD camera. The article describes
the system, outlines the measurement methodology, and presents validation
results. The thermo-reflectance thermography (TRTG) system is capable of
acquiring device surface temperature fields at up to 512x512 points with 0.2
$\mu$m resolution. The setup and measurement methodology are presented, along
with details of the calibration process required to convert changes in measured
surface reflectivity to absolute temperatures. To demonstrate the system's
capabilities, standard gold micro-resistors are activated and their surface
temperature fields are measured. The results of the CCD camera and our existing
laser-based measurement approaches are compared and found to be in very good
agreement. Finally, the system is validated by comparing the temperatures
obtained with the TRTG method with those obtained from electrical resistance
measurements.


title: GRB 060218: The nature of the optical-UV component

abstract:
  The optical-UV component in GRB 060218 is assumed to be due to optically
thick cyclotron emission. The key aspect of this model is the high temperature
of the absorbing electrons. The heat input derives from nuclei accelerated in
semi-relativistic internal shocks, like in ordinary gamma-ray bursts. Coulomb
collisions transfer part of that energy to electrons. Inverse Compton cooling
on the X-ray photons leads to electron temperatures around 100 keV. Such a high
brightness temperature for the optical-UV emission implies an emitting area
roughly equal to that of the thermal X-ray component. This suggests a model in
which the radio, optical-UV and thermal X-ray emission are closely related:
Although the optical-UV and thermal X-ray emission are two separate spectral
components, it is argued that they both come from the photosphere of a
quasi-spherical, continuous outflow, whose interaction with the circumstellar
medium gives rise to the radio emission. The properties of GRB 060218, as
measured in the co-moving frame, are similar to those of ordinary gamma-ray
burst; i.e., the main difference is the much lower value of the bulk Lorentz
factor in GRB 060218. The cyclotron absorption implies a magnetic field in
rough equipartition with the matter energy density in the outflow. Hence, the
magnetic field could have a dynamically important role, possibly with a
magnetar as the central engine.


title:
-55 degrees C to 170 degrees C High Linear Voltage References Circuitry
  in 0.18\`im Cmos Technology

abstract:
  High linear voltage references circuitry are designed and implemented in TSMC
0.18$\mu$m CMOS technology. Previous research has proposed the use of MOS
transistors operating in the weak inversion region to replace the bipolar
devices in conventional PTAT(proportional to absolute temperature) circuits.
However such solutions often have linearity problem in high temperature region
due to the current leaking devices in modern deep sub micron and nano-scale
CMOS technology. The proposed circuit utilized temperature complementation
technique on two voltage references, PTAT and IOAT (independent of absolute
temperature) references, to enhance the linearity and produce a more stable
IOAT voltage reference. Base on the simulation results, the R-squares of both
circuitries are better than 0.999 in a considerable wider temperature range
from -55 degrees C to 170 degrees C. Thus, a fully integrated temperature
sensor with wider temperature range is designed and easily to integrate to
modern system-on-chip designs with minimal efforts.


title: Gauge unification in noncommutative geometry

abstract:
  Gauge unification is widely considered to be a desirable feature for
extensions of the standard model. Unfortunately the standard model itself does
not exhibit a unification of its running gauge couplings but it is required by
grand unified theories as well as the noncommutative version of the standard
model [2].
  We will consider here the extension of the noncommutative standard model by
vector doublets as proposed in [6]. Two consequences of this modification are:
1. the relations of the coupling constants at unification energy are altered
with respect to the well known relation from grand unified theories. 2. The
extended model allows for unification of the gauge couplings at ~10^(13) GeV.


title: Adaptive Coevolutionary Networks: A Review

abstract:
  Adaptive networks appear in many biological applications. They combine
topological evolution of the network with dynamics in the network nodes.
Recently, the dynamics of adaptive networks has been investigated in a number
of parallel studies from different fields, ranging from genomics to game
theory. Here we review these recent developments and show that they can be
viewed from a unique angle. We demonstrate that all these studies are
characterized by common themes, most prominently: complex dynamics and robust
topological self-organization based on simple local rules.


title: Self-organized escape of oscillator chains in nonlinear potentials

abstract:
  We present the noise free escape of a chain of linearly interacting units
from a metastable state over a cubic on-site potential barrier. The underlying
dynamics is conservative and purely deterministic. The mutual interplay between
nonlinearity and harmonic interactions causes an initially uniform lattice
state to become unstable, leading to an energy redistribution with strong
localization. As a result a spontaneously emerging localized mode grows into a
critical nucleus. By surpassing this transition state, the nonlinear chain
manages a self-organized, deterministic barrier crossing. Most strikingly,
these noise-free, collective nonlinear escape events proceed generally by far
faster than transitions assisted by thermal noise when the ratio between the
average energy supplied per unit in the chain and the potential barrier energy
assumes small values.


title: Modeling with structure of resins in electonic compornents

abstract:
  In recent years, interfacial fracture becomes one of the most important
problems in the assessment of reliability of electronics packaging. Especially,
underfill resin is used with solder joints in flip chip packaging for
preventing the thermal fatigue fracture in solder joints. In general, the
interfacial strength has been evaluated on the basis of interfacial fracture
mechanics concept. However, as the size of devices decrease, it is difficult to
evaluate the interfacial strength quantitatively. Most of researches in the
interfacial fracture were conducted on the basis of the assumption of the
perfectly bonding condition though the interface has the micro-scale structure
and the bonding is often imperfect. In this study, the mechanical model of the
interfacial structure of resin in electronic components was proposed.
Bimaterial model with the imperfect bonding condition was examined by using a
finite element analysis (FEA). Stress field in the vicinity of interface
depends on the interfacial structure with the imperfect bonding. In the front
of interfacial crack tip, the behavior of process zone is affected by
interfacial structure. However, the instability of fracture for macroscopic
crack which means the fracture toughness is governed by the stress intensity
factor based on the fracture mechanics concept.


title: Temperature measurement in the Intel(R) CoreTM Duo Processor

abstract:
  Modern CPUs with increasing core frequency and power are rapidly reaching a
point where the CPU frequency and performance are limited by the amount of heat
that can be extracted by the cooling technology. In mobile environment, this
issue is becoming more apparent, as form factors become thinner and lighter.
Often, mobile platforms trade CPU performance in order to reduce power and
manage thermals. This enables the delivery of high performance computing
together with improved ergonomics by lowering skin temperature and reducing fan
acoustic noise. Most of available high performance CPUs provide thermal sensor
on the die to allow thermal management, typically in the form of analog thermal
diode. Operating system algorithms and platform embedded controllers read the
temperature and control the processor power. Improved thermal sensors directly
translate into better system performance, reliability and ergonomics. In this
paper we will introduce the new Intel CoreTM Duo processor temperature sensing
capability and present performance benefits measurements and results.


title: Dark Matter in the U(1) Extended SUSY

abstract:
  The neutralino sector of the U(1) extended SUSY is presented and some
collider and cosmology-related phenomenology discussed.


title:
Reducing the Possibility of Subjective Error in the Determination of the
  Structure-Function-Based Effective Thermal Conductivity of Boards

abstract:
  The thermal response function given to a unit-step dissipation accurately
characterizes the thermal system. Instead of the thermal response function the
so-called structure function describing three-dimensional as the equivalent
model of one-dimensional heat-spreading, created from the thermal response
function with the help of complex mathematical procedures, is often used. Using
the structure function the partial thermal capacity and partial heat resistance
of certain elements of the thermal system can be identified. If the geometrical
measurements of a thermal system of simple geometry and homogeneous material
(such as a homogeneous rod or board, etc.) are known, the coefficient of
thermal conductivity of the material in question can be determined from two
points of the structure function at 2-5 per cent of accuracy. In this paper a
method is presented which applies a wide range/section instead of two points of
the cumulative structure function to determine the thermal coefficient, thus
reducing the subjective error deriving from the selection of the two points.
The above method is presented and illustrated in simulated as well as measured
thermal transient responses.


title: A More Flexible Realization of The SUNRED Algorithm

abstract:
  The high dissipation of integrated circuits means serious problems for
packaging and for the design of complex electronic systems. Another important
area of research and development nowadays is the integration of sensors and
micromechanical systems (MEMS) with electronic circuits. The original
Successive Node Reduction (SUNRED) algorithm handles well the first area but
require revision for electro-thermal or mechanical fields. As a first stage the
updated algorithm is able to solve thermal fields as the original, but with the
application of flexible boundary connection handling, it can be much faster
than the original. By using object-oriented program model the algorithm can
handle non-rectangular 3D fields, and SUNRED mesh resolution is arbitrary, not
have to be the power of two anymore.


title: Orthonormal dilations of Parseval wavelets

abstract:
  We prove that any Parseval wavelet frame is the projection of an orthonormal
wavelet basis for a representation of the Baumslag-Solitar group $$BS(1,2)=<
u,t | utu^{-1}=t^2>.$$ We give a precise description of this representation in
some special cases, and show that for wavelet sets, it is related to symbolic
dynamics. We show that the structure of the representation depends on the
analysis of certain finite orbits for the associated symbolic dynamics. We give
concrete examples of Parseval wavelets for which we compute the orthonormal
dilations in detail; we show that there are examples of Parseval wavelet sets
which have infinitely many non-isomorphic orthonormal dilations.


title:
The application of Artificial Neural Network for the assessment of
  thermal properties of multi-layer semiconductor structure

abstract:
  In this paper, the solution of the problem of identification of thermal
properties of investigated multi-layer structure is presented. In order of
that, artificial neural network was used to find the set of thermal properties
for which the complex contrast characteric derived fits the best to the one
evaluated basing upon experimenatal data.


title: Na61/Shine at the CERN SPS

abstract:
  Status of the new experimental program to study hadron production in
hadron-nucleus and nucleus-nucleus collisions at the CERN SPS will be
presented. In particular, a detailed physics motivation and experimental
strategy will be given for the part of the program related to the physics of
strongly interacting matter: search for the critical point of strongly
interacting matter, study properties of the onset of deconfinement, and high
p_T measurements in p+p and p+A interactions. The planned measurements for the
neutrino T2K and cosmic-ray experiments will also be discussed.


title: A Temperature Analysis of High-power AlGaN/GaN HEMTs

abstract:
  Galliumnitride has become a strategic superior material for space, defense
and civil applications, primarily for power amplification at RF and mm-wave
frequencies. For AlGaN/GaN high electron mobility transistors (HEMT), an
outstanding performance combined together with low cost and high flexibility
can be obtained using a System-in-a-Package (SIP) approach. Since thermal
management is extremely important for these high power applications, a hybrid
integration of the HEMT onto an AlN carrier substrate is proposed. In this
study we investigate the temperature performance for AlGaN/GaN HEMTs integrated
onto AlN using flip-chip mounting. Therefore, we use thermal simulations in
combination with experimental results using micro-Raman spectroscopy and
electrical dc-analysis.


title:
Flow Visualization of The Buoyancy-induced Convective Heat Transfer in
  Electronics Cooling

abstract:
  The aim of this work is to develop a simple optical method for the
visualization of the natural convection flow generated in an electronic system
during its normal operation. The presented experimental set-up allows to reveal
local refractive index changes in a phase objects. A fringe pattern is
acquired, through the cooling fluid under analysis, with a digital camera two
times: the first one with the fluid at rest, the second one with the thermal
load due to the electronic device normal operation. By the means of the MATLAB
processing of the acquired images it’s possible to reveal the shape and
the directions of the thermal flow lines for the cooling fluid. In this way we
can obtain a deeper understanding of the optimal convection working volume or
information for the optimization of the relative spatial positioning of the
several electronic components in a complex electronic system, like a printed
circuit board (PCB). The proposed technique has been tested on two typical heat
extraction situations recurrent in the electronic devices. In this paper are
presented the experimental results of the visualization of the convective flow,
in air, for an heat sink and a power resistor.


title:
The method of non-linear distortions elimination in photoacoustic
  investigation of layered semiconductor structure

abstract:
  This paper presents the consideration of the presence and the influence of
non-linear distortion of photo-acoustic measurement set-up on the results of
thermal properties analysis for the multi-layer semiconductor structure. The
authors propose a method which will eliminate such an influence.


title: Thermal Modeling of high power LED modules

abstract:
  This paper presents a study of accuracy issues in thermal modeling of high
power LED modules on system level. Both physical as well as numerical accuracy
issues are addressed. Incorrect physical assumptions may result in seemingly
correct, but erroneous results. It is therefore important to motivate the
underlying key physical assumptions of a thermal model. In this paper thermal
measurements are used to calibrate a computational fluid dynamics (CFD) model
of a high power LED module model at a reference application condition, and to
validate it at other application conditions.


title:
Reliability Evaluation Method for Electronic Device BGA Package
  Considering the Interaction Between Design Factors

abstract:
  The recent development of electric and electronic devices has been
remarkable. The miniaturization of electronic devices and high integration are
progressing by advances in mounting technology. As a result, the reliability of
fatigue life has been prioritized as an important concern, since the thermal
expansion difference between a package and printed circuit board causes thermal
fatigue. It is demanded a long-life product which has short development time.
However, it is difficult because of interaction between each design factor. The
authors have investigated the influence of various design factors on the
reliability of soldered joints in BGA model by using response surface method
and cluster analysis. By using these techniques, the interaction of all design
factors was clarified. Based upon the analytical results, design engineers can
rate each factor's effect on reliability and assess the reliability of their
basic design plan at the concept design stage.


title:
Creating temperature dependent Ni-MH battery models for low power mobile
  devices

abstract:
  In this paper the methodology and the results of creating temperature
dependent battery models for ambient intelligence applications is presented.
First the measurement technology and the model generation process is presented
in details, and then the characteristic features of the models are discussed.


title: A two-phase approach for detecting recombination in nucleotide sequences

abstract:
  Genetic recombination can produce heterogeneous phylogenetic histories within
a set of homologous genes. Delineating recombination events is important in the
study of molecular evolution, as inference of such events provides a clearer
picture of the phylogenetic relationships among different gene sequences or
genomes. Nevertheless, detecting recombination events can be a daunting task,
as the performance of different recombinationdetecting approaches can vary,
depending on evolutionary events that take place after recombination. We
recently evaluated the effects of postrecombination events on the prediction
accuracy of recombination-detecting approaches using simulated nucleotide
sequence data. The main conclusion, supported by other studies, is that one
should not depend on a single method when searching for recombination events.
In this paper, we introduce a two-phase strategy, applying three statistical
measures to detect the occurrence of recombination events, and a Bayesian
phylogenetic approach in delineating breakpoints of such events in nucleotide
sequences. We evaluate the performance of these approaches using simulated
data, and demonstrate the applicability of this strategy to empirical data. The
two-phase strategy proves to be time-efficient when applied to large datasets,
and yields high-confidence results.


title:
Failure Analysis and Field Failures: a Real Shortcut to Reliability
  Improvement

abstract:
  Starting from two case histories, where only after thorough Failure Analysis
the suddenly appearance of a failure was linked to much earlier events, the
possibility of improving the reliability and of adjusting the reliability
prediction tools are discussed.


title: Electronics Cooling Fan Noise Prediction

abstract:
  Using the finite volume CFD software FLUENT, one fan was studied at a given
flow rate (1.5m3/min) for three different operational rotating speeds : 2,000,
2,350 and 2,700 rpm. The turbulent air flow analysis predicts the acoustic
behavior of the fan. The best fan operating window, i.e. the one giving the
best ratio between noise emissions and cooling performance, can then be
determined. The broadband noise acoustic model is used. As the computation is
steady state, a simple Multiple Reference Frame model (MRF, also known as
stationary rotor approach) is used to represent the fan. This approach is able
to capture the effects of the flow non-uniformity at the fan inlet together
with their impact on the fan performance. Furthermore, it is not requiring a
fan curve as an input to the model. When compared to the available catalog data
the simulation results show promising qualitative agreement that may be used
for fan design and selection purposes.


title:
The central parsecs of Centaurus A: High Excitation Gas, a Molecular
  Disk, and the Mass of the Black Hole

abstract:
  We present two-dimensional gas-kinematic maps of the central region in
Centaurus A. The adaptive optics (AO) assisted SINFONI data from the VLT have a
resolution of 0.12" in K-band. The ionized gas species (Br_gamma, [FeII],
[SiVI]) show a rotational pattern that is increasingly overlaid by
non-rotational motion for higher excitation lines in direction of Cen A's radio
jet. The emission lines of molecular hydrogen (H_2) show regular rotation and
no distortion due to the jet. The molecular gas seems to be well settled in the
gravitational potential of the stars and the central supermassive black hole
and we thus use it as a tracer to model the mass in the central +/-1.5". These
are the first AO integral-field observations on the nucleus of Cen A, enabling
us to study the regularity of the rotation around the black hole, well inside
the radius of influence, and to determine the inclination angle of the gas disk
in a robust way. The gas kinematics are best modeled through a tilted-ring
model that describes the warped gas disk; its mean inclination angle is ~34deg
and the mean position angle of the major axis is ~155deg. The best-fit black
hole mass is M_BH~4.5x10^7 Msolar, based on a "kinematically hot" disk model
where the velocity dispersion is included through the Jeans equation. This
black hole mass estimate is somewhat lower than, but consistent with the mass
values previously derived from ionized gas kinematics. It is also consistent
with the stellar dynamical measurement from the same AO observations, which we
present in a separate paper. It brings Cen A in agreement with the M_BH-sigma
relation.


title: Liquid Cooling of Bright LEDs for Automotive Applications

abstract:
  With the advances in the technology of materials based on GaN, high
brightness white light emitting diodes (LEDs) have flourished over the past few
years and have shown to be very promising in many new illumination applications
such as outdoor illumination, task and decorative lighting as well as aircraft
and automobile illuminations. The objective of this paper is to investigate an
active liquid cooling solution of such LEDs in an application of automotive
headlights. The thermal design from device to board to system level has been
carried out in this research. Air cooling and passive liquid cooling methods
are investigated and excluded as unsuitable, and therefore an active liquid
cooling solution is selected. Several configurations of the active liquid
cooling system are studied and optimisation work has been carried out to find
an optimum thermal performance.


title:
Thermal Design of Power Semiconductor Modules for Mobile Communication
  Systems

abstract:
  We will describe the thermal performance of power semiconductor module, which
consists of hetero-junction bipolar transistors (HBTs), for mobile
communication systems. We calculate the thermal resistance between the HBT
fingers and the bottom surface of a multi-layer printed circuit board (PCB)
using a finite element method (FEM). We applied a steady state analysis to
evaluate the influence of design parameters on thermal resistance of the
module. We found that the thickness of GaAs substrate, the thickness of
multi-layer circuit board, the thermal conductivity of bonding material under
GaAs substrate, and misalignment of thermal vias between each layer of PCB are
the dominant parameter in thermal resistance of the module.


title: Detection and Imaging of He_2 Molecules in Superfluid Helium

abstract:
  We present data that show a cycling transition can be used to detect and
image metastable He$_2$ triplet molecules in superfluid helium. We demonstrate
that limitations on the cycling efficiency due to the vibrational structure of
the molecule can be mitigated by the use of repumping lasers. Images of the
molecules obtained using the method are also shown. This technique gives rise
to a new kind of ionizing radiation detector. The use of He$_2$ triplet
molecules as tracer particles in the superfluid promises to be a powerful tool
for visualization of both quantum and classical turbulence in liquid helium.


title: Gamma-ray blazars: the combined AGILE and MAGIC views

abstract:
  We describe the emission properties of blazars, i.e. the AGNs that, due to
their peculiar orientation w.r.t. the observer, allow the most penetrating and
direct view of their central engine. After showing that the extragalactic
GeV-TeV sky is dominated by blazars of various types, we discuss the kind of
blazars that are likely to be jointly detected by AGILE and MAGIC.


title: Waves, analytical signals, and some postulates of quantum theory

abstract:
  In this paper we apply the formalism of the analytical signal theory to the
Schrodinger wavefunction. Making use exclusively of the wave-particle duality
and the principle of relativistic covariance, we actually derive the form of
the quantum energy and momentum operators for a single nonrelativistic
particle. Without using any more quantum postulates, and employing the
formalism of the characteristic function, we also derive the quantum-mechanical
prescription for the measurement probability in such cases.


title: The structure of line-driven winds

abstract:
  Following procedures pioneered by Castor, Abbott & Klein (1975, [CAK]),
spherically-symmetric supersonic winds for O stars are computed for matching to
plane-parallel moving reversing layers (RL's) from Paper I (Lucy 2007). In
contrast to a CAK wind, each of these solutions is singularity-free, thus
allowing its mass-loss rate to be fixed by the regularity condition at the
sonic point within the RL. Moreover, information propagation in these winds by
radiative-acoustic waves is everywhere outwardly-directed, justifying the
implicit assumption in Paper I that transonic flows are unaffected by
inwardly-directed wave motions.


title:
Growth of Epitaxial MgB2 Thick Films with Columnar Structures by Using
  HPCVD

abstract:
  Epitaxial MgB2 thick films were grown on Al2O3 substrates at 600 oC by using
the hybrid physical chemical vapor deposition (HPCVD) technique. In order to
obtain a high magnesium vapor pressure around the substrates, we used a special
susceptor having a susceptor cap and achieved a very high growth rate of 0.17
um/min. Hexgonal-shaped columnar structures were observed by cross-sectional
and planar view transmission electron microscope (TEM) images. For the
1.7-um-thick film, the Tc was observed to be 40.5 K with a Jc of 1.5 x 10^6
A/cm^2 at 30 K. The vortex pinning mechanism by intercolumnar boundaries will
be discussed.


title: Local electronic properties in nanoscale systems

abstract:
  The local electronic structure on nanoscale chains is investigated
theoretically. We propose a mechanism to explain the even-odd oscillation of
length distribution of atom chains. We study the spatial peak structure as
obtained by scanning tunneling microscopy (STM) constant-current topography as
a function of the electron-electron interaction, band filling and temperature.
The site-dependent magnetic moment is also examined.


title: Mass loss and very low-metallicity stars

abstract:
  Mass loss plays a dominant role in the evolution of massive stars at solar
metallicity. After discussing different mass loss mechanisms and their
metallicity dependence, we present the possibility of strong mass loss at very
low metallicity. Our models at Z=1e-8 show that stars more massive than about
60 solar masses may lose a significant fraction of their initial mass in the
red supergiant phase. This mass loss is due to the surface enrichment in CNO
elements via rotational and convective mixing. Our 85 solar mass model ends its
life as a fast rotating WO type Wolf-Rayet star. Therefore the models predict
the existence of type Ic SNe and long and soft GRBs at very low metallicities.
Such strong mass loss in the red supergiant phase or the Omega-Gamma limit
could prevent the most massive stars from ending as pair-creation supernovae.
  The very low metallicity models calculated are also very interesting from the
nucleosynthesis point of view. Indeed, the wind of the massive star models can
reproduce the CNO abundances of the most metal-poor carbon-rich star known to
date, HE1327-2326. Finally, using chemical evolution models, we are able to
reproduce the evolution of CNO elements as observed in the normal extremely
metal poor stars.


title:
The space density of cataclysmic variables: constraints from the ROSAT
  North Ecliptic Pole Survey

abstract:
  We use the ROSAT North Ecliptic Pole (NEP) survey to construct a small, but
purely X-ray flux-limited sample of cataclysmic variable stars (CVs). The
sample includes only 4 systems, 2 of which (RX J1715.6+6856 and RX
J1831.7+6511) are new discoveries. We present time-resolved spectroscopy of the
new CVs and measure orbital periods of 1.64 \pm 0.02 h and 4.01\pm 0.03 h for
RX 1715.6+6856 and RX J1831.7+6511, respectively. We also estimate distances
for all the CVs in our sample, based mainly on their apparent brightness in the
infrared. The space density of the CV population represented by our small
sample is (1.1 +2.3/-0.7) 10^-5 pc^-3. We can also place upper limits on the
space density of any sub-population of CVs too faint to be included in the NEP
survey. In particular, we show that if the overall space density of CVs is as
high as 2 10^-4 pc^-3 (as has been predicted theoretically), the vast majority
of CVs must be fainter than L_X \simeq 2 10^29 erg/s.


title: Localization of fermionic fields on braneworlds with bulk tachyon matter

abstract:
  Recently, Pal and Skar in [arXiv:hep-th/0701266] proposed a mechanism to
arise the warped braneworld models from bulk tachyon matter, which are endowed
with a thin brane and a thick brane. In this framework, we investigate
localization of fermionic fields on these branes. As in the 1/2 spin case, the
field can be localized on both the thin and thick branes with inclusion of
scalar background. In the 3/2 spin extension, the general supergravity action
coupled to chiral supermultiplets is considered to produce the localization on
both the branes as a result.


title:
Two-electron bound state formation in the t-J-U model for
  exchange-coupled planes

abstract:
  An anisotropic t-J-U model Hamiltonian is used to model electron behaviour in
quasi-2d materials in the dilute limit, and as a highly simplified
representation of the weakly coupled CuO2 planes of the high-Tc cuprates we
model the very poor out-of-plane conductivity via the complete suppression of
interplanar hopping. However, we do include the very weak interplanar
superexchange, and are thus considering a model of exchange-coupled planes. For
an isotropic three-dimensional system in the dilute limit, we find that the
formation of two-particle bound states requires Jc/t ~ 5.9. Also, it is known
that Jc/t = 2 for a 2d square lattice. However, for our model of
exchange-coupled planes any infinitesimal interplanar exchange (Jc = 0) is
adequate to form bound states.


title: Freeness of Conic-Line Arrangements in $\mathbb P^2$

abstract:
  Let ${\mathcal C}= \bigcup_{i=1}^n C_i \subseteq \mathbb{P}^2$ be a
collection of smooth rational plane curves. We prove that the addition-deletion
operation used in the study of hyperplane arrangements has an extension which
works for a large class of arrangements of smooth rational curves, giving an
inductive tool for understanding the freeness of the module $\Omega^1({\mathcal
C})$ of logarithmic differential forms with pole along ${\mathcal C}$. We also
show that the analog of Terao's conjecture (freeness of $\Omega^1({\mathcal
C})$ is combinatorially determined if ${\mathcal C}$ is a union of lines) is
false in this setting.


title:
Wind and boundary layers in Rayleigh-Benard convection. Part 2: boundary
  layer character and scaling

abstract:
  The effect of the wind of Rayleigh-Benard convection on the boundary layers
is studied by direct numerical simulation of an L/H=4 aspect-ratio domain with
periodic side boundary conditions for Ra={10^5, 10^6, 10^7} and Pr=1. It is
shown that the kinetic boundary layers on the top- and bottom plate have some
features of both laminar and turbulent boundary layers. A continuous spectrum,
as well as significant forcing due to Reynolds stresses indicates undoubtedly a
turbulent character, whereas the classical integral boundary layer parameters
-- the shape factor and friction factor (the latter is shown to be dominated by
the pressure gradient) -- scale with Reynolds number more akin to laminar
boundary layers. This apparent dual behavior is caused by the large influence
of plumes impinging onto and detaching from the boundary layer. The
plume-generated Reynolds stresses have a negligible effect on the friction
factor at the Rayleigh numbers we consider, which indicates that they are
passive with respect to momentum transfer in the wall-parallel direction.
However, the effect of Reynolds stresses cannot be neglected for the thickness
of the kinetic boundary layer. Using a conceptual wind model, we find that the
friction factor C_f should scale proportional to the thermal boundary layer
thickness as C_f ~ lambda_Theta, while the kinetic boundary layer thickness
lambda_u scales inversely proportional to the thermal boundary layer thickness
and wind Reynolds number lambda_u ~ lambda_Theta^{-1} Re^{-1}. The predicted
trends for C_f and \lambda_u are in agreement with DNS results.


title: Records Theory

abstract:
  In quantum gravity, one seeks to combine quantum mechanics and general
relativity. In such attempts, one comes across the `problem of time' impasse:
the notion of time is conceptually different in each of these theories. In this
paper, I consider the timeless records approach toward resolving this. Records
are localized, information-containing subconfigurations of a single instant.
Records theory is the study of these and of how science (or history) is to be
abstracted from correlations between them. I critically evaluate motivations
for this approach that have previously appeared in the literature. I provide a
ground-level structure for records theory and discuss what kind of further
tools are needed, illustrated with some toy models: ordinary mechanics,
relatonal particle dynamics, detector models and inhomogeneous perturbations
about homogeneous cosmology.


title:
International Linear Collider Reference Design Report Volume 2: PHYSICS
  AT THE ILC

abstract:
  This article reviews the physics case for the ILC. Baseline running at 500
GeV as well as possible upgrades and options are discussed. The opportunities
on Standard Model physics, Higgs physics, Supersymmetry and alternative
theories beyond the Standard Model are described.


title: Direct mechanical mixing in a nanoelectromechanical diode

abstract:
  We observe direct mechanical mixing in nanoelectromechanical transistors
fabricated in semiconductor materials operating in the radio frequency band of
10-1000 MHz. The device is made of a mechanically flexible pillar with a length
of 240 nm and a diameter of 50 nm, placed between two electrodes in an
impedance matched coplanar wave guide. We find a non-linear IV-characteristic,
which enables radio frequency mixing of two electromagnetic signals via the
nanomechanical transistor. Potential applications for this mixer are
ultrasensitive displacement detection or signal processing in communication
electronic circuits requiring high-throughput insulation.


title:
Broadband X-ray spectrum of the newly discovered broad line radio galaxy
  IGR J21247+5058

abstract:
  In this paper we present radio and high energy observations of the INTEGRAL
source IGR J21247+5058, a broad line emitting galaxy obscured by the Galactic
plane. Archival VLA radio data indicate that IGR J21247+5058 can be classified
as an FRII Broad Line Radio Galaxy. The spectrum between 610 MHz and 15 GHz is
typical of synchrotron self-absorbed radiation with a peak at 8 GHz and a low
energy turnover; the core fraction is 0.1 suggestive of a moderate Doppler
boosting of the base of the jet. The high energy broad-band spectrum was
obtained by combining XMM-Newton and Swift/XRT observation with INTEGRAL/IBIS
data. The 0.4-100 keV spectrum is well described by a power law, with slope
$\Gamma$=1.5, characterised by complex absorption due to two layers of material
partially covering the source and a high energy cut-off around 70-80 keV.
Features such as a narrow iron line and a Compton reflection component, if
present, are weak, suggesting that reprocessing of the power law photons in the
accretion disk plays a negligible role in the source.


title: Radio-Frequency Rectification on Membrane Bound Pores

abstract:
  We present measurements on direct radio-frequency pumping of ion channels and
pores bound in bilipid membranes. We make use of newly developed microcoaxes,
which allow delivering the high frequency signal in close proximity to the
membrane bound proteins and ion channels. We find rectification of the
radio-frequency signal, which is used to pump ions through the channels and
pores.


title: Energy Optimal Control for Quantum System Evolving on SU(1,1)

abstract:
  This paper discusses the energy optimal control problem for the class of
quantum systems that possess dynamical symmetry of SU(1,1), which are widely
studied in various physical problems in the quantum theory. Based on the
maximum principle on Lie group, the complete set of optimal controls are
analytically obtained, including both normal and abnormal extremals. The
results indicate that the normal extremal controls can be expressed by the
Weierstrass elliptic function, while the abnormal extremal controls can only be
constant functions of time t.


title: Spectra, triple and quartic gauge couplings in a Higgsless model

abstract:
  Spectra, triple and quartic gauge couplings of the Higgsless model with gauge
group $SU(2)_L\times SU(2)_R\times U(1)_{B-L}$ defined in warped space are
explored with numerical method. We extend the equation of motions, boundary
conditions and formalism of multi-gauge-boson vertices to the Hirn-Sanz
scenario. By assuming the ideally delocalized fermion profile, we study the
spectra of vector bosons as well as the triple and quartic gauge couplings
among vector bosons. It is found that mass spectra can be greatly modified by
the parameters of QCD power corrections. Meanwhile, the triple and quartic
gauge couplings can deviate from the values of the standard model to at least
$\pm 10%$ and can saturate the LEP2 bounds. We find the triple gauge couplings
of $Z{\bar W}W$ can be $ 50 %$ smaller than the unitarity bounds. While the
triple gauge couplings of ${\bar Z}WW$ is 20% smaller than the unitarity
bounds, which might challenge the detection of ${\bar Z}$ via s channel at LHC
if $m_{\bar Z}> 500$ GeV.


title: Yang-Yang thermodynamics on an atom chip

abstract:
  We investigate the behavior of a weakly interacting nearly one-dimensional
(1D) trapped Bose gas at finite temperature. We perform in situ measurements of
spatial density profiles and show that they are very well described by a model
based on exact solutions obtained using the Yang-Yang thermodynamic formalism,
in a regime where other, approximate theoretical approaches fail. We use
  Bose-gas focusing [Shvarchuck etal., Phys. Rev. Lett. 89, 270404 (2002)] to
probe the axial momentum distribution of the gas, and find good agreement with
the in situ results.


title: Quantum Chaos and Regularity in Ultracold Fermi Gases

abstract:
  Quantum fluctuation of the energy is studied for an ultracold gas of
interacting fermions trapped in a three-dimensional potential. Periodic-orbit
theory is explored, and energy fluctuations are studied versus particle number
for generic regular and chaotic systems, as well for a system defined by a
harmonic confinement potential. Temperature effects on the energy fluctuations
are investigated.


title:
The statistical significance of the N-S asymmetry of solar activity
  revisited

abstract:
  The main aim of this study is to point out the difficulties found when trying
to assess the statistical significance of the North-South asymmetry (hereafter
SSNSA) of the most usually considered time series of solar activity. First of
all, we distinguish between solar activity time series composed by integer or
non-integer and dimensionless data, or composed by non-integer and dimensional
data. For each of these cases, we discuss the most suitable statistical tests
which can be applied and highlight the difficulties to obtain valid information
about the statistical significance of solar activity time series. Our results
suggest that, apart from the need to apply the suitable statistical tests,
other effects such as the data binning, the considered units and the need, in
some tests, to consider groups of data, affect substantially the determination
of the statistical significance of the asymmetry. Our main conclusion is that
the assessment of the statistical significance of the N-S asymmetry of solar
activity is a difficult matter and that an absolute answer cannot be given,
since many different effects influence the results given by the statistical
tests. In summary, the quantitative results about the statistical significance
of the N-S asymmetry of solar activity provided by different authors, as well
as the studies about its behaviour, must be considered with care because they
depend from the chosen values of different parameters or from the considered
units.


title: Lattice QCD Beyond Ground States

abstract:
  In this work, we apply black box methods (methods not requiring input) to
find excited-state energies. A variety of such methods for lattice QCD were
introduced at the 3rd iteration of the numerical workshop series. We first
review a selection of approaches that have been used in lattice calculations to
determine multiple energy states: multiple correlator fits, the variational
method and Bayesian fitting. In the second half, we will focus on a black box
method, the multi-effective mass. We demonstrate the approach on anisotropic
lattice data, extracting multiple states from single correlators. Without
complicated operator construction or specialized fitting programs, the black
box method shows good consistency with the traditional approaches.


title: RHIC physics: short overview

abstract:
  This talk gives a very short overview of some of the important physical
phenomena observed at the Relativistic Heavy Ion Collider (RHIC). The emphasis
is put on the multiplicities, hard probes and the properties of the initial
state.


title:
Electron-impact rotational and hyperfine excitation of HCN, HNC, DCN and
  DNC

abstract:
  Rotational excitation of isotopologues of HCN and HNC by thermal
electron-impact is studied using the molecular {\bf R}-matrix method combined
with the adiabatic-nuclei-rotation (ANR) approximation. Rate coefficients are
obtained for electron temperatures in the range 5$-$6000 K and for transitions
among all levels up to J=8. Hyperfine rates are also derived using the
infinite-order-sudden (IOS) scaling method. It is shown that the dominant
rotational transitions are dipole allowed, that is those for which $\Delta
J=1$. The hyperfine propensity rule $\Delta J=\Delta F$ is found to be stronger
than in the case of He$-$HCN collisions. For dipole allowed transitions,
electron-impact rates are shown to exceed those for excitation of HCN by He
atoms by 6 orders of magnitude. As a result, the present rates should be
included in any detailed population model of isotopologues of HCN and HNC in
sources where the electron fraction is larger than 10$^{-6}$, for example in
interstellar shocks and comets.


title: On the lower central series of an associative algebra

abstract:
  This paper continues the study of the lower central series quotients of an
associative algebra A, regarded as a Lie algebra, which was started in
math/0610410 by Feigin and Shoikhet. Namely, it provides a basis for the second
quotient in the case when A is the free algebra in n generators (note that the
Hilbert series of this quotient was determined earlier in math/0610410).
Further, it uses this basis to determine the structure of the second quotient
in the case when A is the free algebra modulo the relations saying that the
generators have given nilpotency orders. Finally, it determines the structure
of the third and fourth quotient in the case of 2 generators, confirming an
answer conjectured in math/0610410. Finally, in the appendix, the results of
math/0610410 are generalized to the case when A is an arbitrary associative
algebra (under certain conditions on $A$).


title:
Factorization of Numbers with the temporal Talbot effect: Optical
  implementation by a sequence of shaped ultrashort pulses

abstract:
  We report on the successful operation of an analogue computer designed to
factor numbers. Our device relies solely on the interference of classical light
and brings together the field of ultrashort laser pulses with number theory.
Indeed, the frequency component of the electric field corresponding to a
sequence of appropriately shaped femtosecond pulses is determined by a Gauss
sum which allows us to find the factors of a number.


title:
Consistent Treatment of Imaginary Contributions to Higgs-Boson Masses in
  the MSSM

abstract:
  We show how the imaginary parts of the Higgs-Boson self-energies in the MSSM
are consistenly taken into account in the Higgs-Boson mass determination. In a
numerical example we find effects of 5 GeV in the mass difference of the two
heavy neutral Higgs bosons. The imaginary contributions have been included into
the code FeynHiggs.


title: Interplay of Electroweak Precision Observables and B Physics Observables

abstract:
  Indirect information about the possible scale of supersymmetry (SUSY)
breaking is provided by B physics observables (BPO) as well as electroweak
precision observables (EWPO). We review the combination of the constraints
imposed by recent measurements of the BPO BR(b -> s gamma), BR(B_s -> mu+ mu-),
BR(B_u -> tau nu_tau) and Delta M_{B_s} with those obtained from the
experimental measurements of the EWPO M_W, sin^2 theta_eff, Gamma_Z, (g-2)_mu
and M_h. We perform a chi^2 fit to the parameters of the constrained minimal
supersymmetric extension of the Standard Model (CMSSM), in which the
SUSY-breaking parameters are universal at the GUT scale. Assuming that the
lightest supersymmetric particle (LSP) provides the cold dark matter density
preferred by WMAP and other cosmological data, we confirm the preference found
previously for a relatively low SUSY-breaking scale, though there is some
slight tension between the EWPO and the BPO.


title:
Asymptotics and Sequential Closures of Continued Fractions and
  Generalizations

abstract:
  Given a sequence of complex square matrices, $a_n$, consider the sequence of
their partial products, defined by $p_n=p_{n-1}a_{n}$. What can be said about
the asymptotics as $n\to\infty$ of the sequence $f(p_n)$, where $f$ is a
continuous function? A special case of our most general result addresses this
question under the assumption that the matrices $a_n$ are an $l_1$ perturbation
of a sequence of matrices with bounded partial products. We apply our theory to
investigate the asymptotics of the approximants of continued fractions. In
particular, when a continued fraction is $l_1$ limit 1-periodic of elliptic or
loxodromic type, we show that its sequence of approximants tends to a circle in
$\hat{\mathbb{C}}$, or to a finite set of points lying on a circle. Our main
theorem on such continued fractions unifies the treatment of the loxodromic and
elliptic cases, which are convergent and divergent, respectively. When an
approximating sequence tends to a circle, we obtain statistical information
about the limiting distribution of the approximants. When the circle is the
real line, the points are shown to have a Cauchy distribution with parameters
given in terms of modifications of the original continued fraction. As an
example of the general theory, a detailed study of a $q$-continued fraction in
five complex variables is provided. The most general theorem in the paper holds
in the context of Banach algebras. The theory is also applied to $(r,s)$-matrix
continued fractions and recurrence sequences of Poincar\'e type and compared
with closely related literature.


title: Type I Non-Abelian Superconductors in Supersymmetric Gauge Theories

abstract:
  Non-BPS non-Abelian vortices with CP^1 internal moduli space are studied in
an N=2 supersymmetric U(1) x SU(2) gauge theory with softly breaking adjoint
mass terms. For generic internal orientations the classical force between two
vortices can be attractive or repulsive. On the other hand, the mass of the
scalars in the theory is always less than that of the vector bosons; also, the
force between two vortices with the same CP^1 orientation is always attractive:
for these reasons we interpret our model as a non-Abelian generalization of
type I superconductors. We compute the effective potential in the limit of two
well separated vortices. It is a function of the distance and of the relative
colour-flavour orientation of the two vortices; in this limit we find an
effective description in terms of two interacting CP^1 sigma models. In the
limit of two coincident vortices we find two different solutions with the same
topological winding and, for generic values of the parameters, different
tensions. One of the two solutions is described by a CP^1 effective sigma
model, while the other is just an Abelian vortex without internal degrees of
freedom. For generic values of the parameters, one of the two solutions is
metastable, while there are evidences that the other one is truly stable.


title: The K\"unneth formula for nuclear $DF$-spaces and Hochschild cohomology

abstract:
  We consider complexes $(\X, d)$ of nuclear Fr\'echet spaces and continuous
boundary maps $d_n$ with closed ranges and prove that, up to topological
isomorphism, $ (H_{n}(\X, d))^*$ $\iso$ $H^{n}(\X^*,d^*),$ where
$(H_{n}(\X,d))^*$ is the strong dual space of the homology group of $(\X,d)$
and $ H^{n}(\X^*,d^*)$ is the cohomology group of the strong dual complex
$(\X^*,d^*)$. We use this result to establish the existence of topological
isomorphisms in the K\"{u}nneth formula for the cohomology of complete nuclear
$DF$-complexes and in the K\"{u}nneth formula for continuous Hochschild
cohomology of nuclear $\hat{\otimes}$-algebras which are Fr\'echet spaces or
$DF$-spaces for which all boundary maps of the standard homology complexes have
closed ranges. We describe explicitly continuous Hochschild and cyclic
cohomology groups of certain tensor products of $\hat{\otimes}$-algebras which
are Fr\'echet spaces or nuclear $DF$-spaces.


title: Unintegrated parton distributions and correlation functions

abstract:
  We discuss the limitations of the standard collinear approach. The
kinematical approximations necessary to derive the collinear factorization are
insufficient for the description of the exclusive final states. We argue that
for a proper treatment of the final states one needs to use fully unintegrated
parton correlation functions. We introduce the gauge invariant definitions of
these objects and the factorization theorem for one jet production in deep
inelastic scattering.


title:
Modulational instability and nonlocality management in coupled NLS
  system

abstract:
  The modulational instability of two interacting waves in a nonlocal Kerr-type
medium is considered analytically and numerically. For a generic choice of wave
amplitudes, we give a complete description of stable/unstable regimes for zero
group-velocity mismatch. It is shown that nonlocality suppresses considerably
the growth rate and bandwidth of instability. For nonzero group-velocity
mismatch we perform a geometrical analysis of a nonlocality management which
can provide stability of waves otherwise unstable in a local medium.


title:
Sur la persistance des courbes invariantes pour les dynamiques
  holomorphes fibr\'ees lisses

abstract:
  En s'appuyant sur un th\'eor\`me de fonctions implicites de Hamilton nous
montrons la persistance d'une courbe invariante indiff\'rente pour une
dynamique holomorpphe fibr\'ee en classe $C^{\infty}$. Une condition
diophantienne sur la paire de nombres de rotation est demand\'ee. Nous montrons
aussi que cette condition est optimale.


title:
Constraining neutron star tidal Love numbers with gravitational wave
  detectors

abstract:
  Ground-based gravitational wave detectors may be able to constrain the
nuclear equation of state using the early, low frequency portion of the signal
of detected neutron star - neutron star inspirals. In this early adiabatic
regime, the influence of a neutron star's internal structure on the phase of
the waveform depends only on a single parameter lambda of the star related to
its tidal Love number, namely the ratio of the induced quadrupole moment to the
perturbing tidal gravitational field. We analyze the information obtainable
from gravitational wave frequencies smaller than a cutoff frequency of 400 Hz,
where corrections to the internal-structure signal are less than 10 percent.
For an inspiral of two non-spinning 1.4 solar mass neutron stars at a distance
of 50 Mpc, LIGO II detectors will be able to constrain lambda to lambda < 2.0
10^{37} g cm^2 s^2 with 90% confidence. Fully relativistic stellar models show
that the corresponding constraint on radius R for 1.4 solar mass neutron stars
would be R < 13.6 km (15.3 km) for a n=0.5 (n=1.0) polytrope.


title:
Interaction Ruling Animal Collective Behaviour Depends on Topological
  rather than Metric Distance: Evidence from a Field Study

abstract:
  Numerical models indicate that collective animal behaviour may emerge from
simple local rules of interaction among the individuals. However, very little
is known about the nature of such interaction, so that models and theories
mostly rely on aprioristic assumptions. By reconstructing the three-dimensional
position of individual birds in airborne flocks of few thousands members, we
prove that the interaction does not depend on the metric distance, as most
current models and theories assume, but rather on the topological distance. In
fact, we discover that each bird interacts on average with a fixed number of
neighbours (six-seven), rather than with all neighbours within a fixed metric
distance. We argue that a topological interaction is indispensable to maintain
flock's cohesion against the large density changes caused by external
perturbations, typically predation. We support this hypothesis by numerical
simulations, showing that a topological interaction grants significantly higher
cohesion of the aggregation compared to a standard metric one.


title: Seeking a solution of the Pioneer Anomaly

abstract:
  The 1972 and 1973 launched Pioneer 10 and 11 were the first missions to
explore the outer solar system. They achieved stunning breakthroughs in
deep-space exploration. But around 1980 an unmodeled force of \sim 8 \times
10^{-8} cm/s^2, directed approximately towards the Sun, appeared in the
tracking data. It later was unambiguously verified as not being an artifact.
The origin remains unknown (although radiant heat remains a likely cause).
Increasing effort has gone into understanding this anomaly. We review the
situation and describe programs to resolve the issue.


title: Chaoticity for multi-class systems and exchangeability within classes

abstract:
  Classical results for exchangeable systems of random variables are extended
to multi-class systems satisfying a natural partial exchangeability assumption.
It is proved that the conditional law of a finite multi-class system, given the
value of the vector of the empirical measures of its classes, corresponds to
independent uniform orderings of the samples within each class, and that a
family of such systems converges in law if and only if the corresponding
empirical measure vectors converge in law. As a corollary, convergence within
each class to an infinite i.i.d. system implies asymptotic independence between
different classes. A result implying the Hewitt-Savage 0-1 Law is also
extended.


title: Symmetric $\alpha$-stable subordinators and Cauchy problems

abstract:
  We survey the results in Nane (E. Nane, Higher order PDE's and iterated
processes, Trans. American Math. Soc. (to appear)) and Baeumer, Meerschaert,
and Nane (B. Baeumer, M.M. Meerschaert and E. Nane, Brownian subordinators and
fractional Cauchy problems: Submitted (2007)) which deal with PDE connection of
some iterated processes, and obtain a new probabilistic proof of the
equivalence of the higher order PDE's and fractional in time PDE's.


title:
Bandwidth selection for kernel estimation in mixed multi-dimensional
  spaces

abstract:
  Kernel estimation techniques, such as mean shift, suffer from one major
drawback: the kernel bandwidth selection. The bandwidth can be fixed for all
the data set or can vary at each points. Automatic bandwidth selection becomes
a real challenge in case of multidimensional heterogeneous features. This paper
presents a solution to this problem. It is an extension of \cite{Comaniciu03a}
which was based on the fundamental property of normal distributions regarding
the bias of the normalized density gradient. The selection is done iteratively
for each type of features, by looking for the stability of local bandwidth
estimates across a predefined range of bandwidths. A pseudo balloon mean shift
filtering and partitioning are introduced. The validity of the method is
demonstrated in the context of color image segmentation based on a
5-dimensional space.


title: Albedos and diameters of three Mars Trojan asteroids

abstract:
  We observed the Mars Trojan asteroids (5261) Eureka and (101429) 1998 VF31
and the candidate Mars Trojan 2001 FR127 at 11.2 and 18.1 microns using
Michelle on the Gemini North telescope. We derive diameters of 1.28, 0.78, and
<0.52 km, respectively, with corresponding geometric visible albedos of 0.39,
0.32, and >0.14. The albedos for Eureka and 1998 VF31 are consistent with the
taxonomic classes and compositions (S(I)/angritic and S(VII)/achrondritic,
respectively) and implied histories presented in a companion paper by Rivkin et
al. Eureka's surface likely has a relatively high thermal inertia, implying a
thin regolith that is consistent with predictions and the small size that we
derive.


title:
An Alternative Model for the Tidal Evolution of the Earth-Moon-Sun
  System

abstract:
  We have found that the expansion of the universe has immense consequences on
our local systems. We present a model based on cosmic expansion that fits well
with observation. The close approach problem inflicting tidal theory is averted
in this model. We have shown that the astronomical and geological changes of
our local systems are of the order of Hubble constant.


title: Can Inflation Induce Supersymmetry Breaking in a Metastable Vacuum?

abstract:
  We argue that fields responsible for inflation and supersymmetry breaking are
connected by gravitational couplings. In view of the recent progress in
studying supersymmetry breaking in a metastable vacuum, we have shown that in
models of supersymmetric hybrid inflation, where R-symmetry plays an important
role, the scale of supersymmetry breaking is generated dynamically at the end
of inflation and turns out to be consistent with gravity mediation.


title:
Effective Dielectric Tensor for Electromagnetic Wave Propagation in
  Random Media

abstract:
  We derive exact strong-contrast expansions for the effective dielectric
tensor $\epeff$ of electromagnetic waves propagating in a two-phase composite
random medium with isotropic components explicitly in terms of certain
integrals over the $n$-point correlation functions of the medium. Our focus is
the long-wavelength regime, i.e., when the wavelength is much larger than the
scale of inhomogeneities in the medium. Lower-order truncations of these
expansions lead to approximations for the effective dielectric constant that
depend upon whether the medium is below or above the percolation threshold. In
particular, we apply two- and three-point approximations for $\epeff$ to a
variety of different three-dimensional model microstructures, including
dispersions of hard spheres, hard oriented spheroids and fully penetrable
spheres as well as Debye random media, the random checkerboard, and
power-law-correlated materials. We demonstrate the importance of employing
$n$-point correlation functions of order higher than two for high
dielectric-phase-contrast ratio. We show that disorder in the microstructure
results in an imaginary component of the effective dielectric tensor that is
directly related to the {\it coarseness} of the composite, i.e., local
volume-fraction fluctuations for infinitely large windows. The source of this
imaginary component is the attenuation of the coherent homogenized wave due to
scattering. We also remark on whether there is such attenuation in the case of
a two-phase medium with a quasiperiodic structure.


title: Composition of the L5 Mars Trojans: Neighbors, not Siblings

abstract:
  Mars is the only terrestrial planet known to have Tro jan (co-orbiting)
asteroids, with a confirmed population of at least 4 objects. The origin of
these objects is not known; while several have orbits that are stable on
solar-system timescales, work by Rivkin et al. (2003) showed they have
compositions that suggest separate origins from one another. We have obtained
infrared (0.8-2.5 micron) spectroscopy of the two largest L5 Mars Tro jans, and
confirm and extend the results of Rivkin et al. (2003). We suggest that the
differentiated angrite meteorites are good spectral analogs for 5261 Eureka,
the largest Mars Trojan. Meteorite analogs for 101429 1998 VF31 are more varied
and include primitive achondrites and mesosiderites.


title:
Distances to Galactic high-velocity clouds. I. Cohen Stream, complex
  GCP, cloud g1

abstract:
  The high- and intermediate-velocity interstellar clouds (HVCs/IVCs) are
tracers of energetic processes in and around the Milky Way. Clouds with
near-solar metallicity about one kpc above the disk trace the circulation of
material between disk and halo (the Galactic Fountain). The Magellanic Stream
consists of gas tidally extracted from the SMC, tracing the dark matter
potential of the Milky Way. Several other HVCs have low-metallicity and appear
to trace the continuing accretion of infalling intergalactic gas. These
assertions are supported by the metallicities (0.1 to 1 solar) measured for
about ten clouds in the past decade. Direct measurements of distances to HVCs
have remained elusive, however. In this paper we present four new distance
brackets, using VLT observations of interstellar \CaII H and K absorption
toward distant Galactic halo stars. We derive distance brackets of 5.0 to 11.7
kpc for the Cohen Stream (likely to be an infalling low-metallicity cloud), 9.8
to 15.1 kpc for complex GCP (also known as the Smith Cloud or HVC40-15+100 and
with still unknown origin), 1.0 to 2.7 kpc for an IVC that appears associated
with the return flow of the Fountain in the Perseus Arm, and 1.8 to 3.8 kpc for
cloud g1, which appears to be in the outflow phase of the Fountain. Our
measurements further demonstrate that the Milky Way is accreting substantial
amounts of gaseous material, which influences the Galaxy's current and future
dynamical and chemical evolution.


title: Interplay of Coulomb and electron-phonon interactions in graphene

abstract:
  We consider mutual effect of the electron-phonon and strong Coulomb
interactions on each other by summing up leading logarithmic corrections via
the renormalization group approach. We find that the Coulomb interaction
enhances electron coupling to the intervalley A1 optical phonons, but not to
the intravalley E2 phonons.


title: On the naturalness of Einstein's equation

abstract:
  We compute all 2-covariant tensors naturally constructed from a
semiriemannian metric which are divergence-free and have weight greater than
-2.
  As a consequence, it follows a characterization of the Einstein tensor as the
only, up to a constant factor, 2-covariant tensor naturally constructed from a
semiriemannian metric which is divergence-free and has weight 0 (i.e., is
independent of the unit of scale). Since these two conditions are also
satisfied by the energy-momentum tensor of a relativistic space-time, we
discuss in detail how these theorems lead to the field equation of General
Relativity.


title:
Explicit representation of Green function for 3Dimensional exterior
  Helmholtz equation

abstract:
  We have constructed a sequence of solutions of the Helmholtz equation forming
an orthogonal sequence on a given surface. Coefficients of these functions
depend on an explicit algebraic formulae from the coefficient of the surface.
Moreover, for exterior Helmholtz equation we have constructed an explicit
normal derivative of the Dirichlet Green function. In the same way the
Dirichlet-to-Neumann operator is constructed. We proved that normalized
coefficients are uniformly bounded from zero.


title:
Constructing a class of solutions for the Hamilton-Jacobi equation in
  field theory

abstract:
  A new approach leading to the formulation of the Hamilton-Jacobi equation for
field theories is investigated within the framework of jet-bundles and
multi-symplectic manifolds. An algorithm associating classes of solutions to
given sets of boundary conditions of the field equations is provided. The paper
also puts into evidence the intrinsic limits of the Hamilton-Jacobi method as
an algorithm to determine families of solutions of the field equations, showing
how the choice of the boundary data is often limited by compatibility
conditions.


title: Axion-Dilaton Cosmology and Dark Energy

abstract:
  We discuss a class of flat FRW cosmological models based on D=4 axion-dilaton
gravity universally coupled to cosmological background fluids. In particular,
we investigate the possibility of recurrent acceleration, which was recently
shown to be generically realized in a wide class of axion-dilaton models, but
in absence of cosmological background fluids. We observe that, once we impose
the existence of radiation -and matter- dominated earlier stages of cosmic
evolution, the axion-dilaton dynamics is altered significantly with respect to
the case of pure axion-dilaton gravity. During the matter dominated epoch the
scalar fields remain either frozen, due to the large expansion rate, or enter a
cosmological scaling regime. In both cases, oscillations of the effective
equation of state around the acceleration boundary value are impossible. Models
which enter an oscillatory stage in the low redshift regime, on the other hand,
are disfavored by observations. We also comment on the viability of the
axion-dilaton system as a candidate for dynamical dark energy. In a certain
subclass of models, an intermediate scaling regime is succeeded by eternal
acceleration. We also briefly discuss the issue of dependence on initial
conditions.


title: Heterotic String Compactifications on Half-flat Manifolds II

abstract:
  In this paper, we continue the analysis of heterotic string compactifications
on half-flat mirror manifolds by including the 10-dimensional gauge fields. It
is argued, that the heterotic Bianchi identity is solved by a variant of the
standard embedding. Then, the resulting gauge group in four dimensions is still
E6 despite the fact that the Levi-Civita connection has SO(6) holonomy. We
derive the associated four-dimensional effective theories including matter
field terms for such compactifications. The results are also extended to more
general manifolds with SU(3) structure.


title:
Relativistic dynamics of cylindrical shells of counter-rotating
  particles

abstract:
  Although infinite cylinders are not astrophysical entities, it is possible to
learn a great deal about the basic qualitative features of generation of
gravitational waves and the behavior of the matter conforming such shells in
the limits of very small radius. We describe the analytical model using kinetic
theory for the matter and the junction conditions through the shell to obtain
its equation of motion. The nature of the static solutions are analyzed, both
for a single shell as well as for two concentric shells. In this second case,
for a time dependent external shell, we integrate numerically the equation of
motion for several values of the constants of the system. Also, a brief
description in terms of the Komar mass is given to account for the
gravitational wave energy emitted by the system.


title: CD(4) has bounded width

abstract:
  We prove that the constraint languages invariant under a short sequence of
J\'onsson terms (containing at most three non-trivial ternary terms) are
tractable by showing that they have bounded width. This improves the previous
result by Kiss and Valeriote and presents some evidence that the Larose-Zadori
conjecture holds in the congruence-distributive case.


title: Clique-width of unit interval graphs

abstract:
  The clique-width is known to be unbounded in the class of unit interval
graphs. In this paper, we show that this is a minimal hereditary class of
unbounded clique-width, i.e., in every hereditary subclass of unit interval
graphs the clique-width is bounded by a constant.


title:
On the Reduction Process of Nucci-Reduce Algorithm for Computing
  Nonlocal Symmetries of Dynamical Systems:A case study of the Kepler and
  Kepler-related problems

abstract:
  The snags in Nucci(1996)REDUCE algorithm are the intrinsic computational
efforts and the ability to recognize the ignorable variable(s) during the
reduction process of the algorithm. An inappropriate choice of the ignorable
variable(s)may lead to an infinite loop. We construct an isomorphic
transformation which ameliorates these problems, and with which a simple,
definite steps of algebraic process, produced equivalent system of equations to
that of Nucci that are easily solved by Lie point symmetry algorithm.


title:
Signature of sterile species in atmospheric neutrino data at neutrino
  telescopes

abstract:
  The MiniBooNE results have still not been able to comprehensively rule out
the oscillation interpretation of the LSND experiment. So far the so-called
short baseline experiments with energy in the MeV range and baseline of few
meters have been probing the existence of sterile neutrinos. We show how
signatures of these extra sterile states could be obtained in TeV energy range
atmospheric neutrinos travelling distances of thousands of kilometers.
Atmospheric neutrinos in the TeV range would be detected by the upcoming
neutrino telescopes. Of course vacuum oscillations of these neutrinos would be
very small. However, we show that resonant matter effects inside the Earth
could enhance these very tiny oscillations into near-maximal transitions, which
should be hard to miss. We show that imprint of sterile neutrinos could be
unambiguously obtained in this high energy atmospheric neutrino event sample.
Not only would neutrino telescopes tell the presence of sterile neutrinos, it
should also be possible for them to distinguish between the different possible
mass and mixing scenarios with additional sterile states.


title: Partial delocalization of two-component condensates in optical lattices

abstract:
  We study management of localized modes in two-component (spinor)
Bose-Einstein condensates embedded in optical lattices by changing interspecies
interactions. By numerical integration of the coupled Gross-Pitaevskii
equations, we find three different regimes of the delocalizing transition: i)
the partial delocalization when the chemical potential of one of the components
collapses with a gap edge and the respective component transforms into a Bloch
state, while the other component remains localized; ii) the partial
delocalization as consequence of instability of one of the components; and iii)
the situation where the vector soliton reaches limits of the existence domain.
It is shown that there exists a critical value for interspecies scattering
length, below which solutions can be manipulated and above which one of the
components is irreversibly destroyed.


title:
Non-local interactions in hydrodynamic turbulence at high Reynolds
  numbers: the slow emergence of scaling laws

abstract:
  We analyze the data stemming from a forced incompressible hydrodynamic
simulation on a grid of 2048^3 regularly spaced points, with a Taylor Reynolds
number of Re~1300. The forcing is given by the Taylor-Green flow, which shares
similarities with the flow in several laboratory experiments, and the
computation is run for ten turnover times in the turbulent steady state. At
this Reynolds number the anisotropic large scale flow pattern, the inertial
range, the bottleneck, and the dissipative range are clearly visible, thus
providing a good test case for the study of turbulence as it appears in nature.
Triadic interactions, the locality of energy fluxes, and structure functions of
the velocity increments are computed. A comparison with runs at lower Reynolds
numbers is performed, and shows the emergence of scaling laws for the relative
amplitude of local and non-local interactions in spectral space. The scalings
of the Kolmogorov constant, and of skewness and flatness of velocity
increments, performed as well and are consistent with previous experimental
results. Furthermore, the accumulation of energy in the small-scales associated
with the bottleneck seems to occur on a span of wavenumbers that is independent
of the Reynolds number, possibly ruling out an inertial range explanation for
it. Finally, intermittency exponents seem to depart from standard models at
high Re, leaving the interpretation of intermittency an open problem.


title: Cosmological perturbations from stochastic gravity

abstract:
  In inflationary cosmological models driven by an inflaton field the origin of
the primordial inhomogeneities which are responsible for large scale structure
formation are the quantum fluctuations of the inflaton field. These are usually
computed using the standard theory of cosmological perturbations, where both
the gravitational and the inflaton fields are linearly perturbed and quantized.
The correlation functions for the primordial metric fluctuations and their
power spectrum are then computed. Here we introduce an alternative procedure
for computing the metric correlations based on the Einstein-Langevin equation
which emerges in the framework of stochastic semiclassical gravity. We show
that the correlation functions for the metric perturbations that follow from
the Einstein-Langevin formalism coincide with those obtained with the usual
quantization procedures when the scalar field perturbations are linearized.
This method is explicitly applied to a simple model of chaotic inflation
consisting of a Robertson-Walker background, which undergoes a quasi-de-Sitter
expansion, minimally coupled to a free massive quantum scalar field. The
technique based on the Einstein-Langevin equation can, however, deal naturally
with the perturbations of the scalar field even beyond the linear
approximation, as is actually required in inflationary models which are not
driven by an inflaton field such as Starobinsky's trace-anomaly driven
inflation or when calculating corrections due to non-linear quantum effects in
the usual inflaton driven models.


title:
Speeding up Simplification of Polygonal Curves using Nested
  Approximations

abstract:
  We develop a multiresolution approach to the problem of polygonal curve
approximation. We show theoretically and experimentally that, if the
simplification algorithm A used between any two successive levels of resolution
satisfies some conditions, the multiresolution algorithm MR will have a
complexity lower than the complexity of A. In particular, we show that if A has
a O(N2/K) complexity (the complexity of a reduced search dynamic solution
approach), where N and K are respectively the initial and the final number of
segments, the complexity of MR is in O(N).We experimentally compare the
outcomes of MR with those of the optimal "full search" dynamic programming
solution and of classical merge and split approaches. The experimental
evaluations confirm the theoretical derivations and show that the proposed
approach evaluated on 2D coastal maps either shows a lower complexity or
provides polygonal approximations closer to the initial curves.


title: Connecting Polygonizations via Stretches and Twangs

abstract:
  We show that the space of polygonizations of a fixed planar point set S of n
points is connected by O(n^2) ``moves'' between simple polygons. Each move is
composed of a sequence of atomic moves called ``stretches'' and ``twangs''.
These atomic moves walk between weakly simple ``polygonal wraps'' of S. These
moves show promise to serve as a basis for generating random polygons.


title: On the origin of complex stellar populations in star clusters

abstract:
  The existence of complex stellar populations in some star clusters challenges
the understanding of star formation. E.g. the ONC or the sigma Orionis cluster
host much older stars than the main bulk of the young stars. Massive star
clusters (omega Cen, G1, M54) show metallicity spreads corresponding to
different stellar populations with large age gaps. We show that (i) during star
cluster formation field stars can be captured and (ii) very massive globular
clusters can accrete gas from a long-term embedding inter stellar medium and
restart star formation.


title: Estimation of Primordial Spectrum with post-WMAP 3 year data

abstract:
  In this paper we implement an improved (error sensitive) Richardson-Lucy
deconvolution algorithm on the measured angular power spectrum from the WMAP 3
year data to determine the primordial power spectrum assuming different points
in the cosmological parameter space for a flat LCDM cosmological model. We also
present the preliminary results of the cosmological parameter estimation by
assuming a free form of the primordial spectrum, for a reasonably large volume
of the parameter space. The recovered spectrum for a considerably large number
of the points in the cosmological parameter space has a likelihood far better
than a `best fit' power law spectrum up to \Delta \chi^2_{eff} \approx -30. We
use Discrete Wavelet Transform (DWT) for smoothing the raw recovered spectrum
from the binned data. The results obtained here reconfirm and sharpen the
conclusion drawn from our previous analysis of the WMAP 1st year data. A sharp
cut off around the horizon scale and a bump after the horizon scale seem to be
a common feature for all of these reconstructed primordial spectra. We have
shown that although the WMAP 3 year data prefers a lower value of matter
density for a power law form of the primordial spectrum, for a free form of the
spectrum, we can get a very good likelihood to the data for higher values of
matter density. We have also shown that even a flat CDM model, allowing a free
form of the primordial spectrum, can give a very high likelihood fit to the
data. Theoretical interpretation of the results is open to the cosmology
community. However, this work provides strong evidence that the data retains
discriminatory power in the cosmological parameter space even when there is
full freedom in choosing the primordial spectrum.


title: Re-born fireballs in Gamma-Ray Bursts

abstract:
  We consider the interaction between a relativistic fireball and material
assumed to be still located just outside the progenitor star. Only a small
fraction of the expected mass is sufficient to efficiently decelerate the
fireball, leading to dissipation of most of its kinetic energy. Since the
scattering optical depths are still large at distances comparable to the
progenitor radius, the dissipated energy is trapped in the system, accelerating
it to relativistic velocities. The process resembles the birth of another
fireball at radii R~1e11 cm, not far from the transparency radius, and with a
starting bulk Lorentz factors Gamma_c~10. As seen in the observer frame, this
"re--generated" fireball appears collimated within an angle theta_j=1/Gamma_c.
If the central engine works intermittently, the funnel can, at least partially,
refill and the process can repeat itself. We discuss how this idea can help
solving some open issues of the more conventional internal shock scenario for
interpreting the Gamma-Ray Burst properties.


title:
Cross sections and beam asymmetries for $\vev{e}p \to en\pi^+$ in the
  nucleon resonance region for $1.7 \le Q^2 \le 4.5 (GeV)^2$

abstract:
  The exclusive electroproduction process $\vec{e}p \to e^\prime n \pi^+$ was
measured in the range of the photon virtuality $Q^2 = 1.7 - 4.5 \rm{GeV^2}$,
and the invariant mass range for the $n\pi^+$ system of $W = 1.15 - 1.7
\rm{GeV}$ using the CEBAF Large Acceptance Spectrometer. For the first time,
these kinematics are probed in exclusive $\pi^+$ production from protons with
nearly full coverage in the azimuthal and polar angles of the $n\pi^+$
center-of-mass system. The $n\pi^+$ channel has particular sensitivity to the
isospin 1/2 excited nucleon states, and together with the $p\pi^0$ final state
will serve to determine the transition form factors of a large number of
resonances. The largest discrepancy between these results and present modes was
seen in the $\sigma_{LT'}$ structure function. In this experiment, 31,295 cross
section and 4,184 asymmetry data points were measured. Because of the large
volume of data, only a reduced set of structure functions and Legendre
polynomial moments can be presented that are obtained in model-independent fits
to the differential cross sections.