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Displaying entries 31 through 33 of 33 found.
Earth Life > > Human Societies
Contoyiannis, Y., et al.
Self-Organized Criticality in an Epidemic Spread Model.
We select this entry by six Greek physicists among many current papers which seeking to achieve a complex network system analysis for its notice of critical phenomena even this virulent social area. In our cruelest April, however might it dawn that a deeper realm of mathematic codings which inform and constrain our fraught lives are just being revealed?
The previously introduced model of self-organized criticality is here adapted to the case of a virus-induced epidemic. In regard, our study highlights the critical value of virus density over a population. For low values it is proved that the virus-diffusion behavior is safe and is quantitatively similar to epidemical data. But close to the critical point, a critical slowing-down phenomenon emerges. Additionally, the epidemic behavior holds to a second order phase transition. For virus density values higher that the critical value, the epidemic duration becomes extremely prolonged. All these results, together with effective interventions such as contact restriction measures, documents their scientific worthiness. (Abstract)
Future > Self-Selection
Meadows, Victoria, et al, eds.
Tempe: University of Arizona Press,
Seventy-five international astro-authors compose twenty chapters so as to achieve a widest cosmic survey to date as our celestial raiment comes seeded with myriad habitable bioworlds in stochastic solar incubators. A typical entry is Characterizing Exoplanet Habitability by Ravi Kopparapu, et al, see herein.
Future > Self-Selection
A Probabilistic Analysis of the Fermi Paradox in Terms of the Drake Formula.
Two decades after his Our Cosmic Future book, the Institute of Astrophysics, Paris, research director provides a new update of this equation estimate of how many Earth-like worlds might exist. It is also cast another response to Enrico’s 1950s concern that no one actually seems to be there. An underrated factor may have been the lifetime duration of a technical civilization. This would have a major winnowing effect if they could not get their common act together so as to save their home bioworld. Based on our own terminal perils, this situation could imply that a decisive planetary self-realization and selection, indeed a sustainability singularity, is a critical. imperative step. In Prantzos’ expansive view, civilizations are seen to randomly come and go, some for a short period, others may be longer. Earth is not the first, nor the last, but at the present time is alone for these reasons.
In evaluating the number of technological civilizations N in the Galaxy through the Drake formula, emphasis is mostly put on astrophysical and biotechnological factors describing the emergence of a civilization and less on its lifetime L, which is strongly related to its demise. It is argued that this factor is in fact the most important regarding the practical implications of the Drake formula, because it determines the extent of the "sphere of influence" of any technological civilization. The Fermi paradox is then studied by way of a simplified Drake version through Monte Carlo simulations of N civilizations expanding in the Galaxy during their space faring lifetime. In that frame, the probability of "direct contact" is set as the fraction of the Galactic volume occupied collectively by N civilizations. The results are used to find regions in the parameter space where the Fermi paradox holds. (Abstract excerpt)