Testing the precautionary argument after the Lucky Dragon incident

PurposeThis paper uses a historical case study, the controversy over the possibility of climatic extremes caused by hydrogen bomb tests on Pacific Ocean atolls during the 1950s, to show how, in a context of few scientific data and high uncertainty, political affiliations and public concerns shaped two types of argumentation, the “energy” and the “precautionary” arguments.Design/methodology/approachSystematic analysis of publications 1954–1956: scientific and semiscientific articles, publications of C.-N. Martin and contemporary newspaper articles, especially from the Asia–Pacific region.FindingsFirst, epistemological and scientific reasoning about the likelihood of extreme natural events aligned to political convictions and pressure. Second, a geographical and social distribution of arguments: the relativizing “energy argument” prevailed in English-language scientific journals, while the “precautionary argument” dominated in popular journals and newspapers published worldwide. Third, while the “energy argument” attained general scientific consensus within two years, it lost out in the long run. The proponents of the “precautionary argument” raised relevant research questions that, though first rejected in the 1950s, later exposed the fallacies of the “energy argument” (shown for the case of the climatologist William W. Kellogg).Originality/valueIn contrast to the existing secondary literature, this paper presents a balanced view of the weaknesses and strengths of two lines of arguments in the 1950s. Further, this historical study sheds light on how once-discarded scientific theories may ultimately be reconsidered in a completely different political and scientific context, thus justifying the original precautionary argument.

Asymptotic limit of a spatially-extended mean-field FitzHugh–Nagumo model

We consider a spatially extended mean-field model of a FitzHugh–Nagumo neural network, with a rescaled interaction kernel. Our main purpose is to prove that its asymptotic limit in the regime of strong local interactions converges toward a system of reaction–diffusion equations taking account for the average quantities of the network. Our approach is based on a modulated energy argument, to compare the macroscopic quantities computed from the solution of the transport equation, and the solution of the limit system. The main difficulty, compared to the literature, lies in the need of regularity in space of the solutions of the limit system and a careful control of an internal nonlocal dissipation.

Exponential Stability of the Energy of the Wave Equation with Variable Coefficients and a Boundary Distributed Delay

In this paper, we consider a wave equation with space variable coefficients. Due to physical considerations, a distributed delay damping is acted on the part of the boundary. Under suitable assumptions, we prove the exponential stability of the energy based on the use of Riemannian geometry method, the perturbed energy argument, and some observability inequalities. From the applications point of view, our results may provide some qualitative analysis and intuition for the researchers in fields such as engineering, biophysics, and mechanics. And the method is rather general and can be adapted to other evolution systems with variable coefficients (e. g. elasticity plates) as well.

Air entrainment during impact of droplets on liquid surfaces

We study drop impact on a deep pool of the same fluid, with an emphasis on the air layer trapped under the droplets from its formation to its rupture. The penetration velocity of the air layer at a very short time scale prior to its rupture is shown, using an energy argument and experimental verification, to be one-half of the impact velocity. We then deduce the dependence of the rupture position on the liquid viscosity and the impact velocity. We show that the volume of the resulting air bubbles can be related to both those resulting from droplets impacting on solid surfaces and those resulting from rigid spheres impacting on liquid surfaces.

Attenuation of short surface waves by the sea floor via nonlinear sub-harmonic interaction

We consider the indirect mechanism for dissipation of short surface waves through their near-resonant interactions with long sub-harmonic waves that are dissipated by the bottom. Using direct perturbation analysis and an energy argument, we obtain analytic predictions of the evolution of the amplitudes of two short primary waves and the long sub-harmonic wave which form a near-resonant triad, elucidating the energy transfer, from the short waves to the long wave, which may be significant over time. We obtain expressions for the rate of total energy loss of the system and show that this rate has an extremum corresponding to a specific value of the (bottom) damping coefficient (for a given pair of short wavelengths relative to water depth). These analytic results agree very well with direct numerical simulations developed for the general nonlinear wave–wave and wave–bottom interaction problem.

On the Crushing Stress of Open Cell Foams

The compressive response of many foams is characterized by an initial linearly elastic regime which is terminated by instability. For open cell foams instability leads to localized buckling and collapse of zones of cells. Local collapse in these zones is terminated by contact between cell ligaments. In the process collapse spreads to neighboring cells hitherto intact. The spreading of collapse occurs at a well-defined load plateau and continues until most of the cells are thus affected when the material response regains stiffness once more. This type of three-regime compressive response was reproduced numerically by idealizing such foams to be assemblages of space-filling Kelvin cells. The onset of instability involves a long wavelength mode. It has been established by considering a fully periodic column of cells tall enough to accommodate this mode. The crushing response has been evaluated by considering finite size microsections which allow localized deformation to develop. This paper shows that the crushing stress can also be established from the local response of the fully periodic column of cells through an energy argument leading to a Maxwell-type construction.