Understanding Marine Mussel Adhesion

In addition to identifying the proteins that have a role in underwater adhesion by marine mussels, research efforts have focused on identifying the genes responsible for the adhesive proteins, environmental factors that may influence protein production, and strategies for producing natural adhesives similar to the native mussel adhesive proteins. The production-scale availability of recombinant mussel adhesive proteins will enable researchers to formulate adhesives that are water-impervious and ecologically safe and can bind materials ranging from glass, plastics, metals, and wood to materials, such as bone or teeth, biological organisms, and other chemicals or molecules. Unfortunately, as of yet scientists have been unable to duplicate the processes that marine mussels use to create adhesive structures. This study provides a background on adhesive proteins identified in the blue mussel, Mytilus edulis, and introduces our research interests and discusses the future for continued research related to mussel adhesion

Growth or environmental concern: which comes first? Optimal control with pure stock pollutants

\ua9 1999, Springer Japan. This paper models an economy with a stock pollution problem that must choose between productive and environmental investments. Both increase consumption, but only the former leads to economic growth. An optimal control model is solved giving four different paths depending on the initial parameters. For small values of pollution maximizing economic growth is optimal; and for massive pollution all investments are dedicated to environmental abatement. Similarly, the role of discount and savings rates, the relative profitability of abatement and productive investments, and the length of the time horizon are analyzed. Optimal control models simple enough to solve analytically often give intuitively unsatisfactory, boundary-type solutions. Our model, however, does have a large domain of parameter values for which “interior” solutions are optimal. These may start with a period of exclusive productive or environmental investments and then switch over to a mix of investments that corresponds to real-life expectations

Using ambient vibration measurements for risk assessment at an urban scale: from numerical proof of concept to Beirut case study (Lebanon)

Abstract Post-seismic investigations repeatedly indicate that structures having frequencies close to foundation soil frequencies exhibit significantly heavier damages (Caracas 1967; Mexico 1985; Pujili, Ecuador 1996; L’Aquila 2009). However, observations of modal frequencies of soils and buildings in a region or within a current seismic risk analysis are not fully considered together, even when past earthquakes have demonstrated that coinciding soil and building frequencies leads to greater damage. The present paper thus focuses on a comprehensive numerical analysis to investigate the effect of coincidence between site and building frequencies. A total of 887 realistic soil profiles are coupled with a set of 141 single-degree-of-freedom elastoplastic oscillators, and their combined (nonlinear) response is computed for both linear and nonlinear soil behaviors, for a large number (60) of synthetic input signals with various PGA levels and frequency contents. The associated damage is quantified on the basis of the maximum displacement as compared to both yield and ultimate post-elastic displacements, according to the RISK-UE project recommendations (Lagomarsino and Giovinazzi in Bull Earthq Eng 4(4):415–443, 2006), and compared with the damage obtained in the case of a similar building located on rock. The correlation between this soil/rock damage increment and a number of simplified mechanical and loading parameters is then analyzed using a neural network approach. The results emphasize the key role played by the building/soil frequency ratio even when both soil and building behave nonlinearly; other important parameters are the PGA level, the soil/rock velocity contrast and the building ductility. A numerical investigation based on simulation of ambient noise for the whole set of 887 profiles also indicates that the amplitude of H/V ratio may be considered as a satisfactory proxy for site amplification when applied to measurements at urban scale. A very easy implementation of this method, using ambient vibration measurements both at ground level and within buildings, is illustrated with an example application for the city of Beirut (Lebanon). Graphical abstract

Automated assessment of macroseismic intensity from written sources using the fuzzy sets

We apply a computer-aided methodology to assess macroseismic intensity from the descriptions reported by documentary material available for eight Italian earthquakes occurred around the beginning of the instrumental era. The procedure consists of three phases: (i) the identification of significant macroseismic effects on the sources and their archiving in a georeferenced database, (ii) the association between the effects and the degrees of the intensity scale by the comparison with traditional estimates made by macroseismic experts, (iii) the assessment of intensities using a multi-attribute decision-making algorithm based on the Fuzzy Sets logic. This work represents a substantial improvement of our previous efforts as we completely redesigned the three phases of the procedure in the light of the experience of the last 10 years and analyzed six further Italian earthquakes so that our database now includes more than 19,000 encoded effects. Our formalized procedure allows to tracing all of the steps of intensity assessment process so that to identify discrepancies with respect to the expert evaluations that might be possibly due to mistakes or to the incomplete account of the available information. Hence, this approach may be useful for providing a systematic and reproducible intensity assessment as well as for supporting standard manmade assessments. The database of effects we have built could also be employed for testing the internal consistency of the macroseismic scale as well as for designing an improved macroseismic scale, based on consistent statistical criteria