Agricultural expansion is one
of the prime driving forces of global land cover change. Despite the increasing
attention to the factors that cause it, the patterns and processes associated
with indigenous cultivation systems are not well understood. This study
analyzes agricultural change associated with subsistence-based indigenous
production systems in the lower Pastaza River Basin in the Ecuadorian Amazon
through a spatially explicit dynamic model. The model integrates multiple
logistic regression and cellular automata to simulate agricultural expansion at
a resolution consistent with small scale agriculture and deal with inherently
spatial processes. Data on land use and cultivation practices were collected
through remote sensing and field visits, and processed within a geographic
information system framework. Results show that the probability of an area of
becoming agriculture increases with population pressure, in the vicinity of
existing cultivation plots, and proximity to the center of human settlements.
The positive association between proximity to cultivation areas and the
probability of the presence of agriculture clearly shows the spillover effect
and spatial inertia carried by shifting cultivation practices. The model
depicts an ideal shifting cultivation system, with a complete
cropping-fallow-cropping cycle that shows how agricultural areas expand and
contract across space and over time. The model produced relatively accurate
spatial outputs, as shown by the results of a spatial comparison between the
simulated landscapes and the actual one. The study helped understand local
landscape dynamics associated with shifting cultivation systems and their
implications for land management.
At the fundamental level, the 4-dimensional space-time of our direct experience might not be a continuum and discrete quantum entities might “collectively” rule its dynamics. Henceforth, it seems natural to think that in the “low-energy” regime some of its distinctive quantum attributes could, in principle, manifest themselves even at macroscopically large scales. Indeed, when confronted with Nature, classical gravitational dynamics of spinning astrophysical bodies is known to lead to paradoxes: to untangle them, dark matter or modifications to the classical law of gravity are openly considered. In this article, the hypothesis of a fluctuating space-time acquiring “at large distances” the properties of a Bose-Einstein condensate is pushed forward: firstly, it is shown that a natural outcome of this picture is the production of monopoles, dyons, and vortex lines of “quantized” gravitomagnetic—or gyrogravitational—flux along the transition phase; the minimal supported “charge” (and multiples of it) being directly linked with a nonzero (minimal) vacuum energy. Thus, a world of vibrating, spinning, interacting strings whose only elements in their construction are our topological concepts of space and time is envisioned, and they are proposed as tracers of the superfluid features of the space-time: the archetypal embodiment of these physical processes being set by the “gravitational roton”, an analogue of Landau’s classic higher-energy excitation used to explain the superfluid properties of helium II. The far and the near field asymptotics of string line solutions are presented and used to deduce their pair-interaction energy. Remarkably, it is found that two stationary, axis-aligned, quantum space-time vortices with the same sense of spin not only exhibit zones of repulsion but also of attraction, depending on their relative geodetic distance.
This paper compares the irreversible and
reversible rate equations from several uni-uni kinetic mechanisms (Michaelis-Menten,
Hill and Adair equations) and bi-bi mechanisms (single- and double- displacement
equations). In reversible reactions, Haldane relationship is considered to be
identical for all mechanisms considered and reversible equations can be also
obtained from this rela- tionship. Some reversible reactions of the metabolism
are also presented, with their equilibrium constant.