24 research outputs found
Thermofield Dynamics for Twisted Poincare-Invariant Field Theories: Wick Theorem and S-matrix
Poincare invariant quantum field theories can be formulated on
non-commutative planes if the statistics of fields is twisted. This is
equivalent to state that the coproduct on the Poincare group is suitably
twisted. In the present work we present a twisted Poincare invariant quantum
field theory at finite temperature. For that we use the formalism of
Thermofield Dynamics (TFD). This TFD formalism is extend to incorporate
interacting fields. This is a non trivial step, since the separation in
positive and negative frequency terms is no longer valid in TFD. In particular,
we prove the validity of Wick's theorem for twisted scalar quantum field at
finite temperature.Comment: v1: 25 pages, no figure v2: references added; typos corrected; typo
in title correcte
Galilean Covariance and the Gravitational Field
The paper is concerned with the development of a gravitational field theory
having locally a covariant version of the Galilei group. We show that this
Galilean gravity can be used to study the advance of perihelion of a planet,
following in parallel with the result of the (relativistic) theory of general
relativity in the post-Newtonian approximation.Comment: 6 pages, no figures. This paper was accepted for publication on
International Journal of Modern Physics
Noncommutative Thermofield Dynamics
The real-time operator formalism for thermal quantum field theories,
thermofield dynamics, is formulated in terms of a path-integral approach in
non-commutative spaces. As an application, the two-point function for a thermal
non-commutative theory is derived at the one-loop level. The
effect of temperature and the non-commutative parameter, competing with one
another, is analyzed.Comment: 13 pages; to be published in IJMP-A
Materials produced from plant biomass: part II: evaluation of crystallinity and degradation kinetics of cellulose
Pervasive gaps in Amazonian ecological research
Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4
While the increasing availability of global databases on ecological communities has advanced our knowledge
of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In
the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of
Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus
crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced
environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian
Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by
2050. This means that unless we take immediate action, we will not be able to establish their current status,
much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio
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Evidence confirms an anthropic origin of Amazonian Dark Earths.
Arising from: Silva et al. Nature Communications https://doi.org/10.1038/s41467-020-20184-2 (2021