101,708 research outputs found
Tensor models and embedded Riemann surfaces
Tensor models and, more generally, group field theories are candidates for
higher-dimensional quantum gravity, just as matrix models are in the 2d
setting. With the recent advent of a 1/N-expansion for coloured tensor models,
more focus has been given to the study of the topological aspects of their
Feynman graphs. Crucial to the aforementioned analysis were certain subgraphs
known as bubbles and jackets. We demonstrate in the 3d case that these graphs
are generated by matrix models embedded inside the tensor theory. Moreover, we
show that the jacket graphs represent (Heegaard) splitting surfaces for the
triangulation dual to the Feynman graph. With this in hand, we are able to
re-express the Boulatov model as a quantum field theory on these Riemann
surfaces.Comment: 9 pages, 7 fi
3D video coding and transmission
The capture, transmission, and display of
3D content has gained a lot of attention in the last few
years. 3D multimedia content is no longer con fined to
cinema theatres but is being transmitted using stereoscopic
video over satellite, shared on Blu-RayTMdisks,
or sent over Internet technologies. Stereoscopic displays
are needed at the receiving end and the viewer needs to
wear special glasses to present the two versions of the
video to the human vision system that then generates
the 3D illusion. To be more e ffective and improve the
immersive experience, more views are acquired from a
larger number of cameras and presented on di fferent displays,
such as autostereoscopic and light field displays.
These multiple views, combined with depth data, also
allow enhanced user experiences and new forms of interaction
with the 3D content from virtual viewpoints.
This type of audiovisual information is represented by a
huge amount of data that needs to be compressed and
transmitted over bandwidth-limited channels. Part of
the COST Action IC1105 \3D Content Creation, Coding
and Transmission over Future Media Networks" (3DConTourNet)
focuses on this research challenge.peer-reviewe
Dynamical Systems on Networks: A Tutorial
We give a tutorial for the study of dynamical systems on networks. We focus
especially on "simple" situations that are tractable analytically, because they
can be very insightful and provide useful springboards for the study of more
complicated scenarios. We briefly motivate why examining dynamical systems on
networks is interesting and important, and we then give several fascinating
examples and discuss some theoretical results. We also briefly discuss
dynamical systems on dynamical (i.e., time-dependent) networks, overview
software implementations, and give an outlook on the field.Comment: 39 pages, 1 figure, submitted, more examples and discussion than
original version, some reorganization and also more pointers to interesting
direction
Abundance stratification in Type Ia supernovae - V. SN 1986G bridging the gap between normal and subluminous SNe Ia
A detailed spectroscopic analysis of SN 1986G has been performed. SN 1986G
`bridges the gap' between normal and sub luminous type Ia supernova (SNe Ia).
The abundance tomography technique is used to determine the abundance
distribution of the elements in the ejecta. SN 1986G was found to be a low
energy Chandrasekhar mass explosion. Its kinetic energy was 70% of the standard
W7 model (0.9x10erg). Oxygen dominates the ejecta from the outermost
layers down to 9000kms , intermediate mass elements (IME) dominate
from 9000kms to 3500kms with Ni and Fe dominating
the inner layers 3500kms. The final masses of the main elements
in the ejecta were found to be, O=0.33M, IME=0.69M, stable NSE=0.21M,
Ni=0.14M. An upper limit of the carbon mass is set at C=0.02M. The
spectra of SN1986G consist of almost exclusively singly ionised species.
SN1986G can be thought of as a low luminosity extension of the main population
of SN Ia, with a large deflagration phase that produced more IMEs than a
standard SN Ia.Comment: Accepted for publication in MNRAS, update
Developmental changes in foraging-predator avoidance trade-offs in larval lumpfish Cyclopterus lumpus
The 5-12 wk old larvae increased time spent clinging to a surface in the presence of a predator, trading-off time available for foraging in order to reduce the probability of attack. Overall, fewer fish fed in the presence of a predator, and of the fish that did feed, 12 wk old lumpfish also showed a significant decrease in feeding rate (bites per minute swimming) in the presence of a predator. -from Author
Electron Cloud Buildup Characterization Using Shielded Pickup Measurements and Custom Modeling Code at CESRTA
The Cornell Electron Storage Ring Test Accelerator experimental program
includes investigations into electron cloud buildup, applying various
mitigation techniques in custom vacuum chambers. Among these are two 1.1-m-long
sections located symmetrically in the east and west arc regions. These chambers
are equipped with pickup detectors shielded against the direct beam-induced
signal. They detect cloud electrons migrating through an 18-mm-diameter pattern
of small holes in the top of the chamber. A digitizing oscilloscope is used to
record the signals, providing time-resolved information on cloud development.
Carbon-coated, TiN-coated and uncoated aluminum chambers have been tested.
Electron and positron beams of 2.1, 4.0 and 5.3 GeV with a variety of bunch
populations and spacings in steps of 4 and 14 ns have been used. Here we report
on results from the ECLOUD modeling code which highlight the sensitivity of
these measurements to the physical phenomena determining cloud buildup such as
the photoelectron production azimuthal and energy distributions, and the
secondary yield parameters including the true secondary, re-diffused, and
elastic yield values.Comment: Presented at ECLOUD'12: Joint INFN-CERN-EuCARD-AccNet Workshop on
Electron-Cloud Effects, La Biodola, Isola d'Elba, Italy, 5-9 June 2012;
CERN-2013-002, pp. 241-25
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