2,326,413 research outputs found
Thermalization through parton transport
A radiative transport model is used to study kinetic equilibration during the
early stage of a relativistic heavy ion collision. The parton system is found
to be able to overcome expansion and move toward thermalization via parton
collisions. Scaling behaviors show up in both the pressure anisotropy and the
energy density evolutions. In particular, the pressure anisotropy evolution
shows an approximate alpha_s scaling when radiative processes are included. It
approaches an asymptotic time evolution on a time scale of 1 to 2 fm/c. The
energy density evolution shows an asymptotic time evolution that decreases
slower than the ideal hydro evolution. These observations indicate that partial
thermalization can be achieved and viscosity is important for the evolution
during the early longitudinal expansion stage of a relativistic heavy ion
collision.Comment: Presented at the 10th International Conference on Nucleus-Nucleus
Collisions (NN2009), Beijing, China, 16-21 Aug 200
Decomposition theorem on matchable distributive lattices
A distributive lattice structure has been established on the
set of perfect matchings of a plane bipartite graph . We call a lattice {\em
matchable distributive lattice} (simply MDL) if it is isomorphic to such a
distributive lattice. It is natural to ask which lattices are MDLs. We show
that if a plane bipartite graph is elementary, then is
irreducible. Based on this result, a decomposition theorem on MDLs is obtained:
a finite distributive lattice is an MDL if and only if each factor
in any cartesian product decomposition of is an MDL. Two types of
MDLs are presented: and , where
denotes the cartesian product between -element
chain and -element chain, and is a poset implied by any
orientation of a tree.Comment: 19 pages, 7 figure
Structures of q-Deformed Currents
The non-perturbation and perturbation structures of the q-deformed
probability currents are studied. According to two ways of realizing the
q-deformed Heisenberg algebra by the undeformed operators, the perturbation
structures of two q-deformed probability currents are explored in detail.
Locally the structures of two perturbation q-deformed probability currents are
different, one is explicitly potential dependent; the other is not. But their
total contributions to the whole space are the same.Comment: 13. Physics Letters (in press
Antenna-coupled silicon-organic hybrid integrated photonic crystal modulator for broadband electromagnetic wave detection
In this work, we design, fabricate and characterize a compact, broadband and
highly sensitive integrated photonic electromagnetic field sensor based on a
silicon-organic hybrid modulator driven by a bowtie antenna. The large
electro-optic (EO) coefficient of organic polymer, the slow-light effects in
the silicon slot photonic crystal waveguide (PCW), and the broadband field
enhancement provided by the bowtie antenna, are all combined to enhance the
interaction of microwaves and optical waves, enabling a high EO modulation
efficiency and thus a high sensitivity. The modulator is experimentally
demonstrated with a record-high effective in-device EO modulation efficiency of
r33=1230pm/V. Modulation response up to 40GHz is measured, with a 3-dB
bandwidth of 11GHz. The slot PCW has an interaction length of 300um, and the
bowtie antenna has an area smaller than 1cm2. The bowtie antenna in the device
is experimentally demonstrated to have a broadband characteristics with a
central resonance frequency of 10GHz, as well as a large beam width which
enables the detection of electromagnetic waves from a large range of incident
angles. The sensor is experimentally demonstrated with a minimum detectable
electromagnetic power density of 8.4mW/m2 at 8.4GHz, corresponding to a minimum
detectable electric field of 2.5V/m and an ultra-high sensitivity of
0.000027V/m Hz^-1/2 ever demonstrated. To the best of our knowledge, this is
the first silicon-organic hybrid device and also the first PCW device used for
the photonic detection of electromagnetic waves. Finally, we propose some
future work, including a Teraherz wave sensor based on antenna-coupled
electro-optic polymer filled plasmonic slot waveguide, as well as a fully
packaged and tailgated device.Comment: 20 pages, 16 figure
Post processing of multimedia information - concepts, problems, and techniques
Currently, most research work on multimedia information processing is focused on multimedia information storage and retrieval, especially indexing and content-based access of multimedia information. We consider multimedia information processing should include one more level-post-processing. Here "post-processing" means further processing of retrieved multimedia information, which includes fusion of multimedia information and reasoning with multimedia information to reach new conclusions. In this paper, the three levels of multimedia information processing storage, retrieval, and post-processing- are discussed. The concepts and problems of multimedia information post-processing are identified. Potential techniques that can be used in post-processing are suggested, By highlighting the problems in multimedia information post-processing, hopefully this paper will stimulate further research on this important but ignored topic.<br /
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