25,334 research outputs found
Lipdubs as an Instrument to Overcome Invisibility in the Mass-Media. A study of four enthusiastic cases recorded in Quebec, USA, Catalonia and the Basque Country
This paper summarizes the principal conclusions of an investigation into lipdub as an instrument used by social movements in order to get more social influence. Since its creation in 2006, the phenomenon of lipdubs has increased\ud
considerably. This research presents an analytical model for this type of video, providing general data, figures about the number of participants, characteristics of the song used and information about the profile of the audience. The work\ud
highlights the main hypothetical features and components of a good lipdub. Four videos with high impact on Youtube are analyzed. This work claims that, at this time, a good lipdub can be a crucial tool for social movements in order to\ud
overcome the invisibility with which the mass-media often punishes any expression which challenges mainstream tendencies
Effects of Equal Volume But Different Plyometric Jump Training Intensities on Components of Physical Fitness in Physically Active Young Males
TiO₂ coating on autoclaved aerated concrete both for self-cleaning and air-purifying purposes
Evaluation of different TiO2 photocatalysis based strategies to avoid algal fouling on cement based materials
Simulations of GRB Jets in a Stratified External Medium: Dynamics, Afterglow Lightcurves, Jet Breaks and Radio Calorimetry
The dynamics of GRB jets during the afterglow phase is most reliably and
accurately modelled using hydrodynamic simulations. All published simulations,
however, have considered only a uniform external medium, while a stratified
external medium is expected around long duration GRB progenitors. Here we
present simulations of the dynamics of GRB jets and the resulting afterglow
emission for both uniform and stratified external media with for k = 0, 1, 2. The simulations are performed in 2D using the special
relativistic version of the Mezcal code. The dynamics for stratified external
media are broadly similar to those derived for expansion into a uniform
external medium. The jet half-opening angle start increasing logarithmically
with time once the Lorentz factor drops below 1/theta_0. For larger k values
the lateral expansion is faster at early times and slower at late times with
the jet expansion becoming Newtonian and slowly approaching spherical symmetry
over progressively longer timescales. We find that contrary to analytic
expectations, there is a reasonably sharp jet break in the lightcurve for k = 2
although the shape of the break is affected more by the viewing angle than by
the slope of the external density profile. Steeper density profiles are found
to produce more gradual jet breaks while larger viewing angles cause smoother
and later appearing jet breaks. The counter-jet becomes visible as it becomes
sub-relativistic, and for k=0 this results in a clear bump-like feature in the
light curve. However, for larger k values the jet decelerates more gradually,
causing only a mild flattening in the radio light curve that might be hard to
discern when k=2. Late time radio calorimetry is likely to consistently
over-estimate the true energy by up to a factor of a few for k=2, and either
over-predict or under-predict it by a smaller factor for k = 0,1.Comment: 10 pages, 13 figures, submitted to Ap
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