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To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.reseneeco.2006.03.003 Byline: V. Martinet (a), L. Doyen (b) Keywords: Exhaustible resource; Sustainability; Viability kernel Abstract: We examine the conditions for the sustainability of a production-consumption system based on the use of an exhaustible natural resource. Instead of studying the environmental and economic interactions in terms of optimal control, we focus on the viability of the system, defined by a set of constraints combining guaranteed consumption and a stock of resources to be preserved at all times, which refers to a Rawlsian intergenerational equity perspective. Using the mathematical concept of viability kernel, which makes it possible to deal with the consistency between constraints and controlled dynamics, we exhibit the sustainable technological configurations and, whenever possible, the policy options and environmental-economic states required to obtain a perennial system. We point out the flexibility of the sustainable 'extraction-consumption' choices and we show how they are neither reduced to constant consumption paths nor to Hartwick's rule. Numerical simulations illustrate the general results. Author Affiliation: (a) EconomiX (UMR 7166 CNRS-UPX), Universite Paris X-Nanterre, 200 Avenue de la Republique, 92001 Nanterre Cedex, France (b) CERSP (UMR 5173 CNRS-MNHN), Museum National d'Histoire Naturelle, 55 rue Buffon, 75005 Paris, France Article History: Received 25 November 2003; Revised 23 September 2005; Accepted 7 March 2006

Electromigration failure kinetic has been studied with resistance evolution versus time of interconnects during degradation. Tests were performed on dual damascene copper lines, issued from the 65 nm technology node, of various widths and lengths. All samples exhibit similar resistance evolution: an initial step, characterized by its height called Rstep, follows a linear kinetic characterized by its slope called Rslope. These two parameters were systematically extracted; Rstep is proportional to the critical volume of a void spanning the whole section of the line, and Rslope to the copper drift velocity. On one hand, the linewidth does not affect these two parameters. On the other hand, Rslope is highly dependent on the line length because of the Blech effect, while Rstep remains constant. Consequently, it was demonstrated that the classical linear function L/TTF=f(jL), where TTF is the time to failure, j is the current density, and L is the line length, used to study the Blech effect in interconnects could be substituted with the linear function RslopeL=f(jL), confirming that Rslope is a suitable parameter to study void growth kinetics. At 300 °C and 2 MA/cm2, a void growth velocity of 1.15×10-8 μm3/s was thus determined on long lines, and an activation energy of 0.95 eV was found. Finally based on the resistance analysis, an explanation is proposed concerning the larger spread observed on the TTF measured on short lines at low current density. [ABSTRACT FROM AUTHOR]

Avoiding whinges from various and potentially conflicting stakeholders is a major challenge for sustainable development and for the identification of sustainability scenarios or policies for biodiversity and ecosystem services. It turns out that independently complying with whinge thresholds and constraints of these stakeholders is not sufficient because dynamic ecological-economic interactions and uncertainties occur. Thus more demanding no whinge standards are needed. In this paper, we first argue that these new boundaries can be endogenously exhibited with the mathematical concepts of viability kernel and viable controls. Second, it is shown how these no whinge kernels have components, such as harvesting of resources, that should remain within safe corridor while some other components, in particular biodiversity, have only lower conservation limits. Thus, using radar charts, we show how this no whinge kernels can take the shape of a tree that we name viability tree. These trees of viability capture the idea that the unbounded renewal potential of biodiversity combined with a bounded use of the different ecosystem services are crucial ingredients for the sustainability of socio-ecosystems and the design of no whinge policies reconciling the different stakeholders involved. [ABSTRACT FROM AUTHOR]

This paper investigates the role played by cooperation for the sustainable harvesting of an ecosystem. To achieve this, a bio-economic model based on a multi-species dynamics with interspecific relationships and multi-agent catches is considered. A comparison between the non-cooperative and cooperative optimal strategies is carried out. Revisiting the Tragedy of Open Access and over-exploitation issues, it is first proved analytically how harvesting pressure is larger in the non-cooperative case for every species. Then it is examined to what extent gains from cooperation can also be derived for the state of the ecosystem. It turns out that cooperation clearly promotes the conservation of every species when the number of agents is high. When the number of agents remains limited, results are more complicated, especially if a species-by-species viewpoint is adopted. However, we identify two metrics involving the state of every species and accounting for their ecological interactions which exhibit gains from cooperation at the ecosystem scale in the general case. Numerical examples illustrate the mathematical findings. [ABSTRACT FROM AUTHOR]

In European grassland landscapes, grazing and mowing play a key role for the maintenance of high-quality habitats that host important bird populations. As grasslands are also key resources for cattle feeding, there is a need to develop management strategies that achieve the double objective of production and biodiversity conservation. The objective of this study was to use a modelling approach to generate recognisable patterns of bird dynamics in farms composed of different land use proportions, and to compare their production and ecological dimensions. We developed a dynamic model, which linked grassland management to bird population dynamics at the field and farm levels. The model was parameterised for two types of suckling farms corresponding to contrasting levels of grassland intensification and for two bird species of high conservation value. A viability algorithm was used to define and assess viable management strategies for production and ecological performance so as to draw the shape of the relationship between both types of performances for the two types of farms. Our results indicated that, at the farm level, there was a farming system effect with a negative and non-linear relationship linking performance. Improving bird population maintenance was less costly in extensive farms compared with intensive farms. At the field level, the model predicted the timing and intensity of land use, maximising either production or ecological performance. The results suggested that multi-objective grassland management would benefit from public policies that consider levels of organisation higher than the field level, such as the farm or the landscape. [ABSTRACT FROM PUBLISHER]

Abstract: Biodiversity loss in farmlands is widely documented, and agriculture intensification has been identified as a main driver of this decline. Numerous agri-environmental policies have been implemented to assess the negative impacts of agricultural intensification on biodiversity. However, most published studies focus on land-use scenarios, thus neglecting the economic dimension. We develop a bio-economic spatially explicit modelling across 620 small French agricultural areas, which couples a public decision maker under budgetary constraint, regional economic agents in a context of uncertainty and breeding bird dynamics. Using dynamic models, we analyse the direct impacts of several current economic scenarios of the Common Agriculture Policy on common bird communities through five ecological indicators, all related to breeding populations of birds in farmlands: the farmland bird index (FBI), a generalist bird index (GBI), the Shannon diversity index, a community specialization index (CSI) and a community trophic index (CTI). We consider these indicators to scan various functional traits of bird communities. Trends in the different indicators are significantly contrasted pending on economic policy scenarios. Scenarios promoting intensive crops lead to small but specialized communities with more granivorous species, hence a low trophic level for the community. By contrast, promoting extensive grasslands increases the population size, enhances high trophic level but decreases community specialization. Evaluation of agricultural policies should not rely on a single indicator per taxonomic group. In the context of potential reversal of current bird declines, bio-economic modelling, involving farmland incomes, is proposed as a relevant support for decision making about sustainable agri-environmental policies. Promoting extensive grasslands is essential for the sustainable management of bird communities and agriculture. We, however, reveal more complex economic effects and synergies between public incentives, which appear to give interesting leverage for enhancing the bio-economic effectiveness of agricultural policies. [Copyright &y& Elsevier]

The objective of this study was to model the trade-offs between ecological and productive performance of a grassland agroecosystem. We developed a dynamic model linking grass dynamics controlled by livestock grazing to stochastic population dynamics of two wader bird species with high conservation value. Bird dynamics were driven by both direct and indirect effects of grazing. Viable control framework was used to predict grazing strategies ensuring production and conservation and to generate the whole trade-off curve between ecological and productive performance. Bird population size was used as an indicator of ecological performance and the total number of grazing days defined productive performance. Model results show that conciliating ecological and productive performance implies a temporal shift in grazing sequences. The best ecological performance was obtained at intermediate levels of productive performance. Without grazing or with too low a grazing intensity, it was not possible to maintain any of the bird populations due to the indirect effects of grazing on habitat quality. However, too high a level of grazing implied fast population decline for both populations due to direct negative effects of grazing on nest survival. Field data on current grazing regimes and grass height showed a low proportion of suitable fields in our case study area. This result indicates an antagonism between direct and indirect effects of grazing on wader birds, implying the need of very specific management of grassland. Our results illustrate the fact that European grasslands are anthropic habitats which are highly dependent on human activity. In such habitats, trade-off curves are not expected to be strictly decreasing or increasing. [Copyright &y& Elsevier]

Abstract: This paper deals with the regulation of greenhouse gases emissions related to climate change. We consider a stylized climate–economy sequential model and use a cost-effectiveness approach. The analytical study is based on a dynamic programming method. It provides both a tolerable ceiling of concentration and, under simple conditions involving the marginal abatement cost and emission functions, optimal and effective abatement rates. In particular, we prove how the cost effective abatement rate increases with time. Through the optimal time to act function, we examine in detail the role played by greenhouse gases absorption, growth and discount rates. We also analyze the paths from an intergenerational equity perspective. Numerical examples illustrate the general statements. [Copyright &y& Elsevier]

Abstract: Overexploitation of marine resources remains a problem worldwide. Many works advocate for the use of marine reserves as a central element of future stock management in a sustainable perspective. In the present paper, we address the influence of protected areas upon fisheries sustainability within an eco-systemic framework through a dynamic bio-economic model integrating a trophic web, catches and environmental uncertainties. The model is spatially implicit. The evaluation of the ecosystem is designed through the respect along time of constraints of both conservation and guaranteed captures. Using the mathematical concept of invariance kernel in a stochastic context, we define different MPA effects according to biodiversity, catches or mixed points of view. Numerical simulations inspired from data of Aboré coral reef reserve in New Caledonia illustrate the main concepts. In this case, it is pointed out how MPA conservation effect is not necessarily conflicting with MPA catches effect. It is shown that such a co-viability requires medium exploitation rate. Moreover, the climatic changes represented by rise in cyclonic events seem to reinforce these assertions. [Copyright &y& Elsevier]

In European grasslands, livestock grazing is a key driver of habitat quality. However, the specific grazing regimes that favour habitat quality and ensure biodiversity conservation remain largely unknown. This paper develops a dynamic model to predict how livestock grazing may be used to sustain a bird community without penalizing cattle feeding. The model focuses on a grassland grazed by cattle which is also the breeding habitat of three wader species. It integrates the dynamics of a sward, controlled through grazing, and that of three bird populations. Viability theory and dynamic programming are used to reveal viable grazing strategies that ensure the creation of two levels of habitat quality (homogeneous and heterogeneous) whilst ensuring cattle feeding. Viable grazing strategies are ranked through an economic criterion and referred as ecologic or economic grazing. Then using viability population analysis, we assess the extinction risk of the wader community in both levels of habitat quality. Globally, grazing had a more positive effect on the wader community than did the no-grazing scenario. Both levels of habitat quality could be generated through both grazing strategies corresponding to contrasting temporal distributions of livestock densities. Grazing strategies resulted in differential community viability. Ecologic grazing always ensured wader community maintenance, whatever the level of habitat quality targeted. This was not the case for economic grazing which reduced the wader community to two species. Species response showed two contrasting patterns, with a more dramatic decline for lapwings than redshanks in both the no-grazing and heterogeneous habitat quality scenarios. This may lead to conservation problems because of the relationship between population size and probability of extinction observed for lapwings. [Copyright &y& Elsevier]

In this paper, we present an analysis of resistance change events that are occurring during the degradation of interconnects. The events analyzed are the following: 1) a step jump in resistance and 2) a subsequent progressive linear increase of resistance. We first find that the height of the step is correlated with time to fail. We show that the occurrence of a step is likely due to the vertical growth of a void, and the variation of the resistance-step amplitude is due to the variation of the length of the void from sample to sample. We then find that resistance-increase rate of the progressive part is correlated with copper drift velocity. Thus, we show that it is possible to determine an activation energy on every sample, which is performing temperature change during the progressive part of the resistance increase. [ABSTRACT FROM PUBLISHER]