24,991 research outputs found
Generalized Non-Commutative Inflation
Non-commutative geometry indicates a deformation of the energy-momentum
dispersion relation for massless particles.
This distorted energy-momentum relation can affect the radiation dominated
phase of the universe at sufficiently high temperature. This prompted the idea
of non-commutative inflation by Alexander, Brandenberger and Magueijo (2003,
2005 and 2007). These authors studied a one-parameter family of
non-relativistic dispersion relation that leads to inflation: the
family of curves . We show here how the
conceptually different structure of symmetries of non-commutative spaces can
lead, in a mathematically consistent way, to the fundamental equations of
non-commutative inflation driven by radiation. We describe how this structure
can be considered independently of (but including) the idea of non-commutative
spaces as a starting point of the general inflationary deformation of
. We analyze the conditions on the dispersion relation that
leads to inflation as a set of inequalities which plays the same role as the
slow roll conditions on the potential of a scalar field. We study conditions
for a possible numerical approach to obtain a general one parameter family of
dispersion relations that lead to successful inflation.Comment: Final version considerably improved; Non-commutative inflation
rigorously mathematically formulate
A conceptual problem for non-commutative inflation and the new approach for non-relativistic inflationary equation of state
In a previous paper, we connected the phenomenological non-commutative
inflation of Alexander, Brandenberger and Magueijo (2003) and Koh S and
Brandenberger (2007) with the formal representation theory of groups and
algebras and analyzed minimal conditions that the deformed dispersion relation
should satisfy in order to lead to a successful inflation. In that paper, we
showed that elementary tools of algebra allow a group like procedure in which
even Hopf algebras (roughly the symmetries of non-commutative spaces) could
lead to the equation of state of inflationary radiation. In this paper, we show
that there exists a conceptual problem with the kind of representation that
leads to the fundamental equations of the model. The problem comes from an
incompatibility between one of the minimal conditions for successful inflation
(the momentum of individual photons is bounded from above) and the group
structure of the representation which leads to the fundamental inflationary
equations of state. We show that such a group structure, although
mathematically allowed, would lead to problems with the overall consistency of
physics, like in scattering theory, for example. Therefore, it follows that the
procedure to obtain those equations should be modified according to one of two
possible proposals that we consider here. One of them relates to the general
theory of Hopf algebras while the other is based on a representation theorem of
Von Neumann algebras, a proposal already suggested by us to take into account
interactions in the inflationary equation of state. This reopens the problem of
finding inflationary deformed dispersion relations and all developments which
followed the first paper of Non-commutative Inflation.Comment: Phys. Rev. D, 2013, in pres
UEFI BIOS Accessibility for the Visually Impaired
People with some kind of disability face a high level of difficulty for
everyday tasks because, in many cases, accessibility was not considered
necessary when the task or process was designed. An example of this scenario is
a computer's BIOS configuration screens, which do not consider the specific
needs, such as screen readers, of visually impaired people. This paper proposes
the idea that it is possible to make the pre-operating system environment
accessible to visually impaired people. We report our work-in-progress in
creating a screen reader prototype, accessing audio cards compatible with the
High Definition Audio specification in systems running UEFI compliant firmware.Comment: 6 page
Vantagens da cultura protegida: como escolher o túnel certo para a sua cultura
Analise das vantagens da cultura protegida e da utilização de túneis elevados. PrincÃpios a adotar na escolha dos túneis
Sincronização do estro.
Vantagens e aplicações; Bases fisiológicas; Métodos principais; Eficiência biológica.bitstream/item/38617/1/PROCIRM1997.00139.pd
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