870 research outputs found

    Climate change, society issues and sustainable agriculture

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    Despite its prediction 100 years ago by scientists studying CO2, man-made climate change has been officially recognised only in 2007 by the Nobel prize committee. Climate changes since the industrial revolution have already deeply impacted ecosystems. I report major impacts of climate change on waters, terrestrial ecosystems, agriculture, and economy in Europe. The lesson of the climate change story is that humans do not learn from scientists until it really hurts. Furthermore, all society issues cannot be solved anymore using the old, painkiller approach because all issues are now huge, linked, global and fast-developing. In that respect, actual society structures are probably outdated. Here, agronomists are the most advanced scientists to solve society issues because they master the study of complex systems, from the molecule to the global scale. Now more than ever agriculture is a central point to which all society issues are bound. Indeed, humans eat food

    Dynamics of the condensate in zero-range processes

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    For stochastic processes leading to condensation, the condensate, once it is formed, performs an ergodic stationary-state motion over the system. We analyse this motion, and especially its characteristic time, for zero-range processes. The characteristic time is found to grow with the system size much faster than the diffusive timescale, but not exponentially fast. This holds both in the mean-field geometry and on finite-dimensional lattices. In the generic situation where the critical mass distribution follows a power law, the characteristic time grows as a power of the system size.Comment: 27 pages, 7 figures. Minor changes and updates performe

    Correlations in Nuclear Arrhenius-Type Plots

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    Arrhenius-type plots for multifragmentation process, defined as the transverse energy dependence of the single-fragment emission-probability, -ln(p_{b}) vs 1/sqrt(E_{t}), have been studied by examining the relationship of the parameters p_{b} and E_{t} to the intermediate-mass fragment multiplicity . The linearity of these plots reflects the correlation of the fragment multiplicity with the transverse energy. These plots may not provide thermal scaling information about fragment production as previously suggested.Comment: 12 pages, Latex, 3 Postscript figures include

    Person-Affecting Paretian Egalitarianism with Variable Population Size

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    http://web.missouri.edu/~klinechair/on-line%20papers/person-affecting%20APE.docWhere there is a fixed population (i.e., who exists does not depend on what choice an agent makes), the deontic version of anonymous Paretian egalitarianism holds that an option is just if and only if (1) it is anonymously Pareto optimal (i.e., no feasible alternative has a permutation that is Pareto superior), and (2) it is no less equal than any other anonymously Pareto optimal option. We shall develop and discuss a version of this approach for the variable population case (i.e., where who exists does depend on what choice an agent makes). More specifically, we shall develop and discuss it in the context of a person-affecting framework—in which an option is just if and only if it wrongs no one according to certain plausible conditions on wronging

    Falsification Of The Atmospheric CO2 Greenhouse Effects Within The Frame Of Physics

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    The atmospheric greenhouse effect, an idea that many authors trace back to the traditional works of Fourier (1824), Tyndall (1861), and Arrhenius (1896), and which is still supported in global climatology, essentially describes a fictitious mechanism, in which a planetary atmosphere acts as a heat pump driven by an environment that is radiatively interacting with but radiatively equilibrated to the atmospheric system. According to the second law of thermodynamics such a planetary machine can never exist. Nevertheless, in almost all texts of global climatology and in a widespread secondary literature it is taken for granted that such mechanism is real and stands on a firm scientific foundation. In this paper the popular conjecture is analyzed and the underlying physical principles are clarified. By showing that (a) there are no common physical laws between the warming phenomenon in glass houses and the fictitious atmospheric greenhouse effects, (b) there are no calculations to determine an average surface temperature of a planet, (c) the frequently mentioned difference of 33 degrees Celsius is a meaningless number calculated wrongly, (d) the formulas of cavity radiation are used inappropriately, (e) the assumption of a radiative balance is unphysical, (f) thermal conductivity and friction must not be set to zero, the atmospheric greenhouse conjecture is falsified.Comment: 115 pages, 32 figures, 13 tables (some typos corrected

    Origin of Life

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    The evolution of life has been a big enigma despite rapid advancements in the fields of biochemistry, astrobiology, and astrophysics in recent years. The answer to this puzzle has been as mind-boggling as the riddle relating to evolution of Universe itself. Despite the fact that panspermia has gained considerable support as a viable explanation for origin of life on the Earth and elsewhere in the Universe, the issue remains far from a tangible solution. This paper examines the various prevailing hypotheses regarding origin of life like abiogenesis, RNA World, Iron-sulphur World, and panspermia; and concludes that delivery of life-bearing organic molecules by the comets in the early epoch of the Earth alone possibly was not responsible for kick-starting the process of evolution of life on our planet.Comment: 32 pages, 8 figures,invited review article, minor additio

    Effects of boundary conditions on magnetization switching in kinetic Ising models of nanoscale ferromagnets

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    Magnetization switching in highly anisotropic single-domain ferromagnets has been previously shown to be qualitatively described by the droplet theory of metastable decay and simulations of two-dimensional kinetic Ising systems with periodic boundary conditions. In this article we consider the effects of boundary conditions on the switching phenomena. A rich range of behaviors is predicted by droplet theory: the specific mechanism by which switching occurs depends on the structure of the boundary, the particle size, the temperature, and the strength of the applied field. The theory predicts the existence of a peak in the switching field as a function of system size in both systems with periodic boundary conditions and in systems with boundaries. The size of the peak is strongly dependent on the boundary effects. It is generally reduced by open boundary conditions, and in some cases it disappears if the boundaries are too favorable towards nucleation. However, we also demonstrate conditions under which the peak remains discernible. This peak arises as a purely dynamic effect and is not related to the possible existence of multiple domains. We illustrate the predictions of droplet theory by Monte Carlo simulations of two-dimensional Ising systems with various system shapes and boundary conditions.Comment: RevTex, 48 pages, 13 figure

    Magnetism, FeS colloids, and Origins of Life

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    A number of features of living systems: reversible interactions and weak bonds underlying motor-dynamics; gel-sol transitions; cellular connected fractal organization; asymmetry in interactions and organization; quantum coherent phenomena; to name some, can have a natural accounting via physicalphysical interactions, which we therefore seek to incorporate by expanding the horizons of `chemistry-only' approaches to the origins of life. It is suggested that the magnetic 'face' of the minerals from the inorganic world, recognized to have played a pivotal role in initiating Life, may throw light on some of these issues. A magnetic environment in the form of rocks in the Hadean Ocean could have enabled the accretion and therefore an ordered confinement of super-paramagnetic colloids within a structured phase. A moderate H-field can help magnetic nano-particles to not only overcome thermal fluctuations but also harness them. Such controlled dynamics brings in the possibility of accessing quantum effects, which together with frustrations in magnetic ordering and hysteresis (a natural mechanism for a primitive memory) could throw light on the birth of biological information which, as Abel argues, requires a combination of order and complexity. This scenario gains strength from observations of scale-free framboidal forms of the greigite mineral, with a magnetic basis of assembly. And greigite's metabolic potential plays a key role in the mound scenario of Russell and coworkers-an expansion of which is suggested for including magnetism.Comment: 42 pages, 5 figures, to be published in A.R. Memorial volume, Ed Krishnaswami Alladi, Springer 201
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