383 research outputs found
Spatial properties of conjugated network in semicrystalline polymer thin films studied by intensity x-ray cross-correlation functions
We present results of x-ray study of spatial properties of
conjugated networks in polymer thin films. We applied the x-ray
cross-correlation analysis to x-ray scattering data from blends of
poly(3-hexylthiophene) (P3HT) and gold nanoparticles. The Fourier spectra of
the intensity cross-correlation functions for different films contain non-zero
components of orders and measuring the degree of structural order
in the system.Comment: 6 pages, 2 figures, Proceedings ICXOM22 Conference, 2-6 September
2013, Hamburg, German
How strange are compact star interiors ?
We discuss a Nambu--Jona-Lasinio (NJL) type quantum field theoretical
approach to the quark matter equation of state with color superconductivity and
construct hybrid star models on this basis. It has recently been demonstrated
that with increasing baryon density, the different quark flavors may occur
sequentially, starting with down-quarks only, before the second light quark
flavor and at highest densities also the strange quark flavor appears. We find
that color superconducting phases are favorable over non-superconducting ones
which entails consequences for thermodynamic and transport properties of hybrid
star matter. In particular, for NJL-type models no strange quark matter phases
can occur in compact star interiors due to mechanical instability against
gravitational collapse, unless a sufficiently strong flavor mixing as provided
by the Kobayashi-Maskawa-'t Hooft determinant interaction is present in the
model. We discuss observational data on mass-radius relationships of compact
stars which can put constraints on the properties of dense matter equation of
state.Comment: 7 pages, 2 figures, to appear in the Proceedings of the International
Conference SQM2009, Buzios, Rio de Janeiro, Brazil, Sep.27-Oct.2, 200
Five problems in legal maintenance of IT projects
Objective: to assess the compliance of traditional approaches to IT projects legal maintenance with the modern methods of organizing the process of digital products development, to identify the existing problems in this area and suggest possible ways to resolve them. Methods: the research used the logical method and the method of analyzing judicial practice, the inductive method, the method of comparison, and the method of scientific abstraction. Results: digitalization facilitated the development of the services market for IT projects and their maintenance. Legal maintenance of such projects often faces a significant discrepancy between the positions of the customer and the contractor, especially when part of the project is accomplished. Based on the analysis of judicial practice of IT projects using the Agile methodology, the most significant and problematic legal aspects of implementation were identified, and conflict situations between customers and performers of IT projects were analyzed.Scientific novelty: five key problems of IT projects legal maintenance that use flexible management methods are identified. A universal model for implementing legal functions in Agile projects is proposed.Practical significance: the proposed scheme of legal maintenance of IT projects can be used to regulate the legal relationships of their participants and may help to reduce the conflict level and speed up the process of digital products development using the Agile methodology
Theory and Applications of X-ray Standing Waves in Real Crystals
Theoretical aspects of x-ray standing wave method for investigation of the
real structure of crystals are considered in this review paper. Starting from
the general approach of the secondary radiation yield from deformed crystals
this theory is applied to different concreat cases. Various models of deformed
crystals like: bicrystal model, multilayer model, crystals with extended
deformation field are considered in detailes. Peculiarities of x-ray standing
wave behavior in different scattering geometries (Bragg, Laue) are analysed in
detailes. New possibilities to solve the phase problem with x-ray standing wave
method are discussed in the review. General theoretical approaches are
illustrated with a big number of experimental results.Comment: 101 pages, 43 figures, 3 table
Structure and cooling of compact stars
We study the structure and evolution of neutron stars (NS) the interiors of
which are modeled using microscopic approaches and constrained by the condition
that the equation of state (EoS) of matter extrapolated to high densities
should not contradict known observational data from compact stars and
experimental data from heavy-ion collisions (HIC). We use modern cooling
simulations to extract distributions of NS masses required to reproduce those
of the yet sparse data in the Temperature-Age (TA) plane. By comparing the
results with a mass distribution for young, nearby NSs used in population
synthesis we can sharpen the NS cooling constraints.Comment: 22 pages, 9 figures, Lecture notes for the Helmholtz International
Summer School on "Dense Matter in Heavy-Ion Collisions and Astrophysics",
JINR, Dubna, August 21 - September 1, 200
Design of 280 GHz feedhorn-coupled TES arrays for the balloon-borne polarimeter SPIDER
We describe 280 GHz bolometric detector arrays that instrument the
balloon-borne polarimeter SPIDER. A primary science goal of SPIDER is to
measure the large-scale B-mode polarization of the cosmic microwave background
in search of the cosmic-inflation, gravitational-wave signature. 280 GHz
channels aid this science goal by constraining the level of B-mode
contamination from galactic dust emission. We present the focal plane unit
design, which consists of a 1616 array of conical, corrugated feedhorns
coupled to a monolithic detector array fabricated on a 150 mm diameter silicon
wafer. Detector arrays are capable of polarimetric sensing via waveguide
probe-coupling to a multiplexed array of transition-edge-sensor (TES)
bolometers. The SPIDER receiver has three focal plane units at 280 GHz, which
in total contains 765 spatial pixels and 1,530 polarization sensitive
bolometers. By fabrication and measurement of single feedhorns, we demonstrate
14.7 FHWM Gaussian-shaped beams with 1% ellipticity in a 30%
fractional bandwidth centered at 280 GHz. We present electromagnetic
simulations of the detection circuit, which show 94% band-averaged,
single-polarization coupling efficiency, 3% reflection and 3% radiative loss.
Lastly, we demonstrate a low thermal conductance bolometer, which is
well-described by a simple TES model and exhibits an electrical noise
equivalent power (NEP) = 2.6 10 W/,
consistent with the phonon noise prediction.Comment: Proceedings of SPIE Astronomical Telescopes + Instrumentation 201
Centrality Behaviour of J/ Production in Na50
The J/ production in 158 A GeV Pb-Pb interactions is studied, in the
dimuon decay channel, as a function of centrality, as measured with the
electromagnetic or with the very forward calorimeters. After a first sharp
variation at mid centrality, both patterns continue to fall down and exhibit a
curvature change at high centrality values. This trend excludes any
conventional hadronic model and is in agreement with a deconfined quark-gluon
phase scenario. We report also preliminary results on the measured charged
multiplicity, as given by a dedicated detector.Comment: 5 pages, 7 figures (in eps) talk given at XXXI International
Symposium on Multiparticle Dynamics, Sep. 1-7, 2001, Datong China URL
http://ismd31.ccnu.edu.cn
The dependence of the anomalous J/psi suppression on the number of participant nucleons
The observation of an anomalous J/psi suppression in Pb-Pb collisions by the NA50 Collaboration can be considered as the most striking indication for the deconfinement of quarks and gluons at SPS energies. In this Letter, we determine the J/psi suppression pattern as a function of the forward hadronic energy E-ZDC measured in a Zero Degree Calorimeter (ZDC). The direct connection between EZDC and the geometry of the collision allows us to calculate, within a Glauber approach, the precise relation between the number of participant nucleons N-part and E-ZDC. Then, we check if the experimental data can be better explained by a sudden or a smooth onset of the anomalous J/psi suppression as a function of the number of participants. (C) 2001 Elsevier Science B.V. All rights reserved.info:eu-repo/semantics/publishedVersio
First results from NA60 on low mass muon pair production in In-In collisions at 158 GeV/nucleon
The NA60 experiment at the CERN SPS studies dimuon production in
proton-nucleus and nucleus-nucleus collisions. The combined information from a
novel vertex telescope made of radiation-tolerant silicon pixel detectors and
from the muon spectrometer previously used in NA50 allows for a precise
measurement of the muon vertex and a much improved dimuon mass resolution. We
report on first results from the data taken for Indium-Indium collisions at 158
AGeV/nucleon in 2003, concentrating on a subsample of about 370 000 muon pairs
in the mass range GeV/. The light vector mesons and
are completely resolved, with a mass resolution of about 23 MeV/
at the . The transverse momentum spectra of the are measured over
the continuous range GeV/c; the inverse slope parameter of
the spectra is found to increase with centrality, with an average value of
MeV.Comment: 9 pages, 6 figures. Plenary talk, SQM2004 conference, Cape Town,
South Africa 15-20 September, 2004. To be published in Journal of Physics G:
Nuclear and Particle Physic
Core collapse supernovae in the QCD phase diagram
We compare two classes of hybrid equations of state with a hadron-to-quark
matter phase transition in their application to core collapse supernova
simulations. The first one uses the quark bag model and describes the
transition to three-flavor quark matter at low critical densities. The second
one employs a Polyakov-loop extended Nambu-Jona-Lasinio (PNJL) model with
parameters describing a phase transition to two-flavor quark matter at higher
critical densities. These models possess a distinctly different temperature
dependence of their transition densities which turns out to be crucial for the
possible appearance of quark matter in supernova cores. During the early post
bounce accretion phase quark matter is found only if the phase transition takes
place at sufficiently low densities as in the study based on the bag model. The
increase critical density with increasing temperature, as obtained for our PNJL
parametrization, prevents the formation of quark matter. The further evolution
of the core collapse supernova as obtained applying the quark bag model leads
to a structural reconfiguration of the central proto-neutron star where, in
addition to a massive pure quark matter core, a strong hydrodynamic shock wave
forms and a second neutrino burst is released during the shock propagation
across the neutrinospheres. We discuss the severe constraints in the freedom of
choice of quark matter models and their parametrization due to the recently
observed 2 solar mass pulsar and their implications for further studies of core
collapse supernovae in the QCD phase diagram.Comment: 19 pages, 4 figures, CPOD2010 conference proceedin
- âŠ