1,721,183 research outputs found
Ecodynamics: the role of time and entropy terms in ecological modelling as a key for evolutive thermodynamics
No full textThe solution conformation and dynamics of biomolecules in the presence of internal motions: The use of jump models for the 1H NMR analysis of relaxation data
No full textA jump model has been used to obtain motional information from proton relaxation parameters in complex molecular systems in which multiple internal motions are present. The proposed analysis takes into account changes in orientation and magnitude of interproton vectors, due to overall and internal motions. Intrinsic relaxation contributions can be calculated if the probability for each spatial configuration is independently known. From these contributions jump frequencies may be evaluated, yielding information on local molecular mobility. © 1982 Società Italiana di Fisica
Internal motions of aromatic amino acid side chains. Selective excitation nuclear relaxation and scalar coupling constant analysis on a model system
No full textThe model compound N-acetyl-L-phenylalanine methyl ester was used to investigate the motional behavior of aromatic amino acid residues in peptides and proteins. A combined analysis of proton scalar coupling constants and selective excitation spin-lattice relaxation rates yields a self-consistent insight into (i) relaxation mechanisms, (ii) overall molecular motion, and (iii) local mobilities along the side chain. At the operative frequency of 270 MHz, the amino acid derivative tumbling fulfilled the condition ωo2τc2 ≪1. The proton relaxation pathway was dominated by the intramolecular dipole-dipole relaxation mechanism. Extensive internal motions of the side chain were found. © 1979 American Chemical Society
The origins of irreversibility
No full textThis article is a theoretical contribution dedicated to Boltzmann's theorem revisited in light of the studies of Mario Ageno, late professor of Physics at the University of Rome (La Sapienza), who showed an interesting new point of view on probability and uncertainty in his book The Origins of Irreversibility. The discussion takes into account the equation of Ilya Prigogine, Nobel Prize winner in Chemistry, for the calculation of entropy production per unit time. The main point is that the authors claim that there are three different conditions: (a) the tendency towards disorder (Boltzmann) as in the case of gas; (b) the Ageno contribution related to the collisions of molecules against the walls: in this case Ageno claims that the origin of irreversibility derives from the tendency towards a macrostate richer in microstates; (c) the presence in the liquids, living systems and water of possible dissipative structures: in this case self-organization is the most probable state (Prigogine's order out of chaos) and the tendency is towards an ordered state
The Ecological Footprint Depth: preliminary consideration for national accounting
No full textNatural capital is becoming a limiting factor to human well-being and definitively to sustainability: ecological overshoot, all ineludible reality, is one of the most important evidence of it. Maintaining (and investing in) capital natural is essential to secure living condition on this planet. For this reason the differentiation between the use of natural capital flows and the depletion of natural capital stock is becoming matter of particular interest in sustainability theory. In our previous work (How deep is the footprint? A 3D representation 2009) we proposed a variant to the traditional Ecological Footprint framework, to capture for these two opposite concepts. In particularly a 3D-EF model was presented and a new dimension called Ecological Footprint Depth of simply Depth was introduced. The aim of this paper is to propose an adaptation of the model for the national level. A theoretical explanation oil how to distinguish the two components is also offered. Two nations, Italy and the USA, were considered as reference for this study
Biodiversity vs. clonation: a different way of modelling
No full textBiological evolution is characterized by a creativity of structures and species, being the product of 4,600 million years of co-evolution of interrelated complex histories. Clonation tends to render pieces of life the same for man's utility and therefore works in an opposite direction to the history of our planet.
The models of genetic engineering are based on molecular reductionism, the absence of time (they are reversible) and a hidden ideology (the so called "pensiero unico"): the sole purpose of utility to man. The development of evolutionary models and of eco-informatics to study the complexity of evolving ecosystems is needed to respond to the ongoing attack on nature by modem technologies, our insane manner of producing and consuming and the hidden ideology of homologation to "pensiero unico".
Evolutionary models and eco-informatics need to be:
a) systemic and not reductionist, modelling relations and not single molecular structures or single biological species;
b) irreversible in the thermodynamic sense explained by Prigogine, so as, to reflect the intrinsic evolutionary properties of ecosystems and living systems;
c) integrated, so as to reflect the various "Gestalt" or points of view (epistemological, thermodynamic, biological, eco-economic,...).
They also need to consider the sustainability of development, environmental constraints and diversity (biological, cultural and social) of the various geographical areas. What applies to the Atlantic does not necessarily hold for the Mediterranean
Sustainable development at local level and “anthropic resilience”. Sustainability indicators from SPIn-Eco project
No full textThe socio economic context of the Province of Siena (central Italy) is peculiar because it is characterised by the same development trend of western countries but, at the same time, it is not completely affected by the negative aspects of this. The SPIn-Eco project is a triennial research program with the purpose of assessing the environmental conditions of the Province of Siena (Tuscany, central Italy) and its 36 municipalities. It is a deep analysis of the state of the territorial system by a complete set of instruments and indicators. This paper shows the aggregated results of the analysis for the northern area of the Province of Siena, called Val d'Elsa, which is composed by 6 municipalities. The area is characterised by variegated geomorphology, environmental aspects and urbanization. At the same time, each municipality is traditionally inclined to the development of some activities: agriculture, industry, craft, tourism respectively.
The paper presents an environmental assessment of the use of resources at a local level by using some methodologies and sustainability indicators: emergy evaluation (introduced by Howard Odum), greenhouse gas inventory (according to the Revised 1996 IPCC Guidelines for National Greenhouse Gas Inventories) and ecological footprint analysis (introduced by M. Wackernagel and W. Rees). The discussion section deals with the environmental, social and economic aspects of these under a sustainable perspective. We believe that the distribution of different peculiarities on the territory could be emphasized as a sort of "anthropic (or urban) resilience" of the system by a correct territorial planning activity towards sustainability
Towards an evolutionary thermodynamics of ecosystems
No full textThe epistemological and thermodynamic bases to proceed towards an evolutionary physics are presented, having in mind the new theories of the Bruxelles's school (Ilya Prigogine). Namely the relationship between evolutionary thermodynamics and complexity of ecosystems has been taken into account, focusing the attention on the role of time, emergence and creation of events. Energy vs. entropy is discussed in more details, in terms of dissipative structures and Prigogine's thermodynamics
Uso di Recurrence Plot per l’individuazione di transizioni nella dinamica di sistemi dissipativi
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