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Showing papers by "International Institute for Applied Systems Analysis published in 1997"


Journal ArticleDOI
TL;DR: A formal framework for modeling evolutionary dynamics with special emphasis on the generation of diversity through branching of the evolutionary tree is presented and defined as the long term growth rate which is influenced by the biotic environment leading to frequency-dependent selection.
Abstract: We present a formal framework for modeling evolutionary dynamics with special emphasis on the generation of diversity through branching of the evolutionary tree. Fitness is defined as the long term growth rate which is influenced by the biotic environment leading to frequency-dependent selection. Evolution can be described as a dynamics in space with variable number of dimensions corresponding to the number of different types present. The dynamics within a subspace is governed by the local fitness gradient. Entering a higher dimensional subspace is possible only at a particular type of attractors where the population undergoes evolutionary branching.

492 citations


Journal ArticleDOI
TL;DR: In this article, mixed integer programming is used to incorporate into the model the non-convex relation between declining specific investment in energy technologies and overall experience or capacities installed, and the initial results achieved with this approach show the importance of early investment in new technology developments.
Abstract: Technology dynamics is endogenized into a bottom-up energy systems model. Mixed integer programming is used to incorporate into the model the non-convex relation between declining specific investment in energy technologies and overall experience or capacities installed. The initial results achieved with this approach show the importance of early investment in new technology developments. New technologies will not become cheaper irrespective of research, development, and demonstration (RD & D) decisions; they will do so only if determined RD&D policies and investment strategies enhance their development.

274 citations


Journal ArticleDOI
11 Jul 1997-Science
TL;DR: In this article, the Croll/Milankovitch theory was used to explain the spectral features in ocean sediment records, which support the theory that the cycles of glaciation were driven by variations in the inclination of Earth's orbital plane.
Abstract: Narrow spectral features in ocean sediment records offer strong evidence that the cycles of glaciation were driven by astronomical forces. Two million years ago, the cycles match the 41,000-year period of Earth's obliquity. This supports the Croll/Milankovitch theory, which attributes the cycles to variations in insolation. But for the past million years, the spectrum is dominated by a single 100,000-year feature and is a poor match to the predictions of insolation models. The spectrum can be accounted for by a theory that derives the cycles of glaciation from variations in the inclination of Earth's orbital plane.

214 citations


Journal ArticleDOI
19 Jun 1997-Nature
TL;DR: The authors used simulation techniques to derive probability distributions of population sizes and age structures for 13 regions of the world up to the year 2100 and found that there is a probability of two-thirds that the world's population will not double in the twenty-first century.
Abstract: Most national and international agencies producing population projections avoid addressing explicitly the issue of uncertainty. Typically, they provide either a single projection or a set of low, medium and high variants, and only very rarely do they give these projections a probabilistic interpretation. Probabilistic population projections have been developed for specific industrialized countries, mostly the United States, and are based largely on time-series analysis. On a global level, time-series analysis is not applicable because there is a lack of appropriate data, and for conceptual reasons such as the structural discontinuity caused by the demographic transition. Here we report on a new probabilistic approach that makes use of expert opinion on trends in fertility, mortality and migration, and on the 90 per cent uncertainty range of those trends in different parts of the world. We have used simulation techniques to derive probability distributions of population sizes and age structures for 13 regions of the world up to the year 2100. Among other things, we find that there is a probability of two-thirds that the world's population will not double in the twenty-first century.

202 citations


Journal ArticleDOI
TL;DR: This paper provides a brief overview of basic adaptive dynamics theory, outlines recent work within the field and evaluates the prospects for the future.
Abstract: An international group of scientists gathered in August 1996 for a workshop in the Matra mountains of Hungary to report and assess recent developments and open research topics in the new field of adaptive dynamics. This paper provides a brief overview of basic adaptive dynamics theory, outlines recent work within the field and evaluates the prospects for the future.

190 citations


Journal ArticleDOI
TL;DR: In this paper, the authors investigated what we know about population growth, what can be projected with reasonable certainty, and what is pure speculation, and set a frame for analysing demographic driving forces that are expected to increase human demand and pressures on land and water resources.
Abstract: Future world population growth is fuelled by two components: the demographic momentum, which is built into the age composition of current populations, and changes in reproductive behaviour and mortality of generations yet to come. This paper investigates, by major world regions and countries, what we know about population growth, what can be projected with reasonable certainty, and what is pure speculation. The exposition sets a frame for analysing demographic driving forces that are expected to increase human demand and pressures on land and water resources. These have been contrasted with current resource assessments of regional availability and use of land, in particular with estimates of remaining land with cultivation potential. In establishing a balance between availabilty of land resources and projected needs, the paper distinguishes regions with limited land and water resources and high population pressure from areas with abundant resources and low or moderate demographic demand. Overall, it is estimated that two-thirds of the remaining balance of land with rainfed cultivation potential is currently covered by various forest ecosystems and wetlands. The respective percentages by region vary between 23% in Southern Africa to 89% in South-Eastern Asia. For Latin America and Asia the estimated share of the balance of land with cultivation potential under forest and wetland ecosystems is about 70%, in Africa this is about 60%. If these were to be preserved, the remaining balance of land with some potential for rainfed crop cultivation would amount to some 550 million hectares. The regions which will experience the largest difficulties in meeting future demand for land resources and water, or alternatively have to cope with much increased dependency on external supplies, include foremost Western Asia, South-Central Asia, and Northern Africa. A large stress on resources is to be expected also in many countries of Eastern, Western and Southern Africa

181 citations


Journal ArticleDOI
TL;DR: In this article, the regularized decomposition algorithm for two stage stochastic problems is improved by using a primal simplex method for solving subproblems, which facilitates crash and warm starts, and allows more freedom when creating the model.

135 citations


Journal ArticleDOI
TL;DR: In this article, the authors address the issue of path-dependent selection and inefficiency, counterfactual methods and empirical evidence employed in this research trajectory, and ask whether these results suggest a large welfare loss.

125 citations


Journal ArticleDOI
TL;DR: Multi-objective optimization coupled with multi-criteria decision analysis (MCDA) techniques have been used to analyze various land use scenarios, considering simultaneously several objectives such as maximizing revenues from crop and livestock production, maximizing district self-reliance in agricultural production, minimizing costs of production and environmental damages from erosion.

85 citations


Journal ArticleDOI
TL;DR: A comparative analysis on the real data sets shows that the nonparametric linear programming formulation introduced in this paper may offer an interesting robust alternative to parametric statistical formulations for the multigroup discriminant problem.
Abstract: In this paper we introduce a nonparametric linear programming formulation for the general multigroup classification problem. Previous research using linear programming formulations has either been limited to the two-group case, or required complicated constraints and many zero-one variables. We develop general properties of our multigroup formulation and illustrate its use with several small example problems and previously published real data sets. A comparative analysis on the real data sets shows that our formulation may offer an interesting robust alternative to parametric statistical formulations for the multigroup discriminant problem.

67 citations


Journal ArticleDOI
TL;DR: In this paper, a methodology for analyzing analytic hierarchy process (AHP) rankings if the pairwise preference judgments are uncertain (stochastic) is presented, where the relative preference statements are represented by judgment intervals, rather than single values, and the rankings resulting from a traditional AHP analysis based on single judgment values may be reversed, and therefore incorrect.
Abstract: This paper presents a methodology for analyzing Analytic Hierarchy Process (AHP) rankings if the pairwise preference judgments are uncertain (stochastic). If the relative preference statements are represented by judgment intervals, rather than single values, then the rankings resulting from a traditional (deterministic) AHP analysis based on single judgment values may be reversed, and therefore incorrect. In the presence of stochastic judgments, the traditional AHP rankings may be stable or unstable, depending on the nature of the uncertainty. We develop multivariate statistical techniques to obtain both point estimates and confidence intervals of the rank reversal probabilities, and show how simulation experiments can be used as an effective and accurate tool for analyzing the stability of the preference rankings under uncertainty. If the rank reversal probability is low, then the rankings are stable and the decision maker can be confident that the AHP ranking is correct. However, if the likelihood of rank reversal is high, then the decision maker should interpret the AHP rankings cautiously, as there is a subtantial probability that these rankings are incorrect. High rank reversal probabilities indicate a need for exploring alternative problem formulations and methods of analysis. The information about the extent to which the ranking of the alternatives is sensitive to the stochastic nature of the pairwise judgments should be valuable information into the decision-making process, much like variability and confidence intervals are crucial tools for statistical inference. We provide simulation experiments and numerical examples to evaluate our method. Our analysis of rank reversal due to stochastic judgments is not related to previous research on rank reversal that focuses on mathematical properties inherent to the AHP methodology, for instance, the occurrence of rank reversal if a new alternative is added or an existing one is deleted.

Journal ArticleDOI
TL;DR: It is shown that the concept of stochastic mollifier gradient leads to easily implementable computational procedures for systems with Lipschitz and discontinuous objective functions.

Journal ArticleDOI
01 Jan 1997-Geology
TL;DR: In this paper, the authors show that although eccentricity affected the local climate, it is orbital inclination that drove the variations in the global ice volume for the past million years, and suggest that orbital inclination also plays some role in the coarse fraction.
Abstract: Ocean Drilling Program Site 806 in the western Pacific shows evidence of a remarkably constant average sedimentation rate. This feature allows us to analyze ancient climate proxies without the need for “orbital tuning,” a standard procedure in prior work, but one that can lead to biased results. Spectral analysis of stable oxygen isotope ratios at this site, a proxy for global ice volume, shows a single narrow peak with a period ≈ 100 k.y., a result that supports our model which links glacial cycles to variations in the inclination of the Earth's orbit. In contrast, spectral analysis of the coarse component fraction of the sediment (primarily foraminifera) shows a structure characteristic of standard Milankovitch theory, with a triplet of peaks with periods near those expected from the Earth's eccentricity: 95, 125, and 400 k.y. Bispectral analysis confirms these linkages but suggests that orbital inclination also plays some role in the coarse fraction. From the clear presence of both signals in different proxies at the same site, we conclude that although eccentricity affected the local climate, it is orbital inclination that drove the variations in the global ice volume for the past million years.

Posted Content
TL;DR: In this article, a two-stage spatial catastrophic model is extended to dynamic cases reflecting dependencies of risk accumulation processes in time, which can be used for the analysis of decisions under changing frequencies of events and values of properties.
Abstract: This paper deals with the development of decision making tools for managing catastrophic (low probability - high consequences) risks. Catastrophes produce rare and highly correlated claims, which depend on various decision variables, i.e., coverages at different locations, mitigation measures and reinsurance agreements. Joint probability distributions of these claims depicting their complex spatial and temporal interactions and effects of decision variables are analytically intractable. Spatial stochastic models of catastrophes can bypass these difficulties. Catastrophic models combine the simulation of realistic and geographically explicit catastrophic events with the differentiation of property values and insurance coverages in different locations of the region. Catastrophic models can be combined with stochastic optimization techniques to aid decision making on the spatial diversification of contracts, insurance premiums, reinsurance requirements, effects of mitigation measures, and the use of other financial mechanisms. The aim of this paper is to extend a two-stage spatial catastrophic model to dynamic cases reflecting dependencies of risk accumulation processes in time. This extension is important since it can be used for the analysis of decisions under changing frequencies of events and values of properties. It is also possible to incorporate catastrophes caused by the clustering in time of such events as rains and droughts due to persistence in climate. The model can be used by individual insurers, pools of insurers or regulatory authorities.

Journal ArticleDOI
TL;DR: A general constraint aggregation technique is proposed for convex optimization problems where a set of convex inequalities and linear equations is replaced by a single surrogate inequality formed as a linear combination of the original constraints.
Abstract: A general constraint aggregation technique is proposed for convex optimization problems At each iteration a set of convex inequalities and linear equations is replaced by a single surrogate inequality formed as a linear combination of the original constraints After solving the simplified subproblem, new aggregation coefficients are calculated and the iteration continues This general aggregation principle is incorporated into a number of specific algorithms Convergence of the new methods is proved and speed of convergence analyzed Next, dual interpretation of the method is provided and application to decomposable problems is discussed Finally, a numerical illustration is given

Journal ArticleDOI
TL;DR: In this paper, a simple model is described to illustrate the following possibilities for increased carbon fixation by improved forest management: large-scale reforestation and afforestation, replacement of stands with low productivity and replacement of so called soft deciduous species and "climax" stands, and implementation of rational silviculture (thinning).
Abstract: Huge areas of the Russian forests suffer from insufficient forest management. A scenario has been developed for an improved management program that would be implemented over the next 40 years. Possible options have been aggregated into three interlinked groups: increase in forest productivity through improvement of the forest conditions and the structure of the Forest Fund, decrease of carbon release by mitigation of disturbance regimes, and improvement of landscape management. One prerequisite in developing this scenario was that the cost of sequestering one ton of carbon should not exceed US$3 (1992 dollar value). In this article a simple model is described to illustrate the following possibilities for increased carbon fixation by improved forest management: large-scale reforestation and afforestation, replacement of stands with low productivity and replacement of so called soft deciduous species and “climax” stands, and implementation of rational silviculture (thinning). The results indicate a potential for an increase in carbon fixation in Russian forest ecosystems of 24.4 Pg over 100 years, after the first year that the actions discussed are implemented. The net sink of carbon was determined to be 16.5 Pg in the “low” estimate and 42.5 Pg in the “high” estimate. There are, however, many uncertainties in the data and there are difficulties in adequately modeling the possibilities for implementation under current conditions in Russia. In spite of these uncertainties, we conclude that there is great potential for economically justified increased carbon fixation through improved forest management in Russia.

Journal ArticleDOI
TL;DR: It is posited that the increase in life expectancy is the product of a learning process to remove the accidents and obstacles on the way to the full life potential of an individual: longevity.

Journal ArticleDOI
TL;DR: In this paper, regression equations for basic fractions of forest phytomass have been developed for the European-Ural part of Russia based on available experimental data and publications (preliminarily examined 962 sample plots and aggregations).
Abstract: Regression equations for basic fractions of forest phytomass have been developed for the European-Ural part of Russia based on available experimental data and publications (preliminarily examined 962 sample plots and aggregations). 8 main forest forming species (pine, spruce, oak, birch, beech, aspen, alder, lime) which were involved into analysis cover in European Russia about 95% of total forested areas. The equations allow to evaluate the ratio between phytomass fractions weight and growing stock by species, age and site indexes. The application of the equations to the Forest State Account data (1988) gives the total (living) phytomass in forest ecosystems of European Russia (forested area of 166.0 Mha, growing stock of 20.28 bln m3) of 15.47 Pg drt matter (density 9.32 kg/m2). The total carbon pool was estimated 7.64 Pg C with average density 4.60 kg C/m2 in 1988. Analysis of uncertainties of data and used methods showed that the results which based on FSA data probably underestimate real values for about 5% with standard error +/- 7-8% with confidential (apriori) probability 0.8-0.9. Used this assumption unbiased estimate of total storage of phytomass in forest vegetation were calculated for 1993 of 16.94 Pg (average density 10.36 kg/m2 ) and for C content respectively (8.37 Tg and 5.03 kg/m2 respectively). The changes of forest phytomass in 1966-1993 were estimated of 4.73 Pg (or about 174 Tg of dry matter/year) and for C - 2.34 Pg, i.e. the European Russian forests provided during 1966-1993 net sink of carbon in forest vegetation about 87 Tg C annually.

Posted Content
TL;DR: In this paper, the authors present a macroeconomic growth model in which investment in physical capital exhibits positive externalities which raise the stock of knowledge, and treat physical capital and knowledge as two separate variables.
Abstract: We present a macroeconomic growth model in which investment in physical capital exhibits positive externalities which raise the stock of knowledge. Treating physical capital and knowledge as two separate variables, we show that the model can generate endogenous growth. It is demonstrated that there exist at most two balanced growth paths (BGPs) with endogenous growth. If the BGP is unique, it is always saddle-point stable. If there are two BGPs, the first is always stable in the saddle-point sense, whereas the second cannot be a saddle point. Instead, the second is either totally stable, giving rise to local indeterminacy, or completely unstable. Further, we can demonstrate that a Hopf bifurcation may occur at the second BGP, leading to persistent fluctuations. Besides local indeterminacy, the model may also give rise to global indeterminacy.

Journal ArticleDOI
TL;DR: It is shown that an asymptotically optimal sampling strategy in the case of normal errors can be obtained by solving a convex optimization problem and a regularization is proposed that leads to a simple one-step allocation rule.

Journal ArticleDOI
TL;DR: In this article, an asset market model, supplemented by explicit treatment of smuggling and second-economy activity, is used to study the paths of black-market exchange rates, secondeconomy prices, hoarding stocks, and privately held dollar balances following policy reforms.

Journal ArticleDOI
TL;DR: In this article, the authors present a collection of arguments that came to the author's mind when reading through some of the literature on sustainable development Similar to rather general sociological theories, these sustainability concepts - which are rooted in biological observations and theories of non-human biosphere - describe elements of a universal development philosophy but they fail to take into account some basic characteristics of how human societies and economics function and develop for instance, the role of conflict, the fundamental diversity of interests and lifestyles, power imbalance in and between human societies, and the specific dynamics of pioneer development.
Abstract: This paper is a provocative collection of arguments that came to the author's mind when reading through some of the literature on sustainable development Similar to rather general sociological theories, these sustainability concepts - which are rooted in biological observations and theories of non-human biosphere - describe elements of a universal development philosophy But they fail to take into account some of the most basic characteristics of how human societies and economics function and develop For instance, they largely ignore the role of conflict, the fundamental diversity of interests and lifestyles, power imbalance in and between human societies, and the specific dynamics of pioneer development Most importantly, they define life-support systems almost exclusively in bio-geophysical terms - ignoring the fact that human development primarily depends on the accumulated scientific and technological knowledge and on the cultural heritage of institutions and arrangements which represent successful solutions of social, economic and political problems

Journal Article
TL;DR: The authors discusses the changing nature of research and development (RD the other was the USA After the breakup of the Soviet Union, the R&D sector went into a precipitous decline that continued until at least 1995 The collection of papers in this report addresses what went wrong and a number of broad issues are covered, such as whether the decline of the RD how the structure and organization of Russian-applied RD and what role government policy should play.
Abstract: This Research Report discusses the changing nature of research and development (RD the other was the USA After the breakup of the Soviet Union, the R&D sector went into a precipitous decline that continued until at least 1995 The collection of papers in this report addresses what went wrong A number of broad issues are covered, such as whether the decline of the RD how the structure and organization of Russian-applied RD and what role government policy should play in Russian-applied R&D Chapters in the report were written by Russian senior officials and by scholars of R&D policy from outside Russia

Posted Content
TL;DR: In this article, the authors studied the demographic and educational futures of Jordan, Lebanon, Syria, the West Bank and the Gaza Strip, and provided a demographic picture of the region in 2044.
Abstract: This report studies the demographic and educational futures of Jordan, Lebanon, Syria, the West Bank and the Gaza Strip. These are areas of potential and existing conflicts, where population growth has many political dimensions. The report, however, abstains from discussing these political issues and focuses on future demographic aspects. It is clear that this report could raise some questions on the sensitivity of the region to future population prospects. Assumptions for the population projections are based on the analysis of past and present trends in changes in population growth, age structure, fertility levels and trends, contraceptive use, marriage and child bearing patterns, mortality, migration, education, and enrollment levels. Based on this analysis, three population projection paths - low, central, and high - were designed and lead to three population figures for each area in 2044. Educational levels of the population were judged determinant to the future level of population growth. In all scenarios, the levels of enrollment varied consistently with fertility and mortality assumptions to change the levels of education in the population. Results were then analyzed to provide a demographic picture of the region in 2044. This study provides interesting insights into the demography of these countries, especially with regard to the momentum of population growth and education levels. Jordan and Syria have experienced high rates of population growth in the recent past. In Jordan, these rates have been reinforced by the migration of Palestinian refugees from the West Bank and the Gaza Strip into the country. The first signs (important fertility reductions and gains in life expectancy) of a demographic transition became visible in the late 1980s in the two countries. The population in Jordan and Syria will continue to grow rapidly in the future. The central scenario, which gives the most likely path under current conditions, implies a tripling of the population of Jordan and almost a tripling of the population in Syria. Still these countries have a high potential for lesser population growth. Lebanon will remain a country of low population growth, with the annual growth rate ranging on average from 1.0 to 1.3 percent per year between 1994 and 2044. The most extreme results in terms of population growth are found in the case of the West Bank and the Gaza Strip. Even under the low scenario, which combines very rapid fertility and mortality declines and rapid educational improvements, the West Bank and the Gaza Strip more than quadruple in population size in the fifty years of the projection period due to the high momentum of past population growth. However, all scenarios show substantial declines in the proportion of people with a low education - less than a primary education - even under the most pessimistic assumptions.

Book ChapterDOI
04 Jun 1997
TL;DR: The algorithm is not based on genetic algorithms, but is inspired by a biological theory of coevolving species, and sets no constraints on the number of neurons and the architecture of a network, and develops network topology and parameters simultaneously simultaneously.
Abstract: An evolutionary algorithm for the development of neural networks with arbitrary connectivity is presented The algorithm is not based on genetic algorithms, but is inspired by a biological theory of coevolving species It sets no constraints on the number of neurons and the architecture of a network, and develops network topology and parameters like weights and bias terms simultaneously Designed for generating neuromodules acting in embedded systems like autonomous agents, it can be used also for the evolution of neural networks solving nonlinear control problems Here we report on a first test, where the algorithm is applied to a standard control problem: the balancing of an inverted pendulum

Journal ArticleDOI
01 Jun 1997
TL;DR: In this article, the authors explored the impediments to exports that small transition economies face once the initial systemic changes and the switch to Western markets have taken place, and the main questions that arise are the following: are the impediment to exports mostly external and demand related or do they have more to do with supply, i.e. rooted in the inherited or newly created domestic conditions and national policies?
Abstract: This article reports about a research project that explored the impediments to exports that small transition economies face once the initial systemic changes and the switch to Western markets have taken place. In this kind of exploration, the main questions that arise are the following: Are the impediments to exports mostly external and demand related or do they have more to do with supply, i.e. rooted in the inherited or newly created domestic conditions and national policies? Are the impediments to exports similar or significantly different across the STEs? How have governments enhanced exports after losing much of their freedom to interfere in the activities of enterprises? How do enterprises assess their opportunities to export versus selling on the domestic market? What typical strategies have enterprises developed to overcome existing barriers? To what extent do export impediments shape the evolving geographic structure of trade, and which industrial branches seem to show sustainable export potential in the STEs? What role does Western capital in the form of joint ventures play in the development of competitive export potential in STEs? Unlike the recovery of domestic sales, the expansion of exports has relatively little to do with domestic macroeconomic factors and much to do with numerous and highly differentiated microeconomic conditions, both in the country concerned and in its foreign markets. For this reason, our investigation places an emphasis on microeconomic empirical evidence....

Posted Content
TL;DR: In this paper, the authors deal with the emergence of cooperative strategies in repeated games, and present a vast class of equilibrium solutions based on Markovian strategies, called equalizers.
Abstract: This report deals with two questions concerning the emergence of cooperative strategies in repeated games. The first part is concerned with the Perfect Folk Theorem and presents a vast class of equilibrium solutions based on Markovian strategies. Simple strategies, called equalizers, are introduced and discussed: if players adopt such strategies, the same payoff results for every opponent. The second part analyzes strategies implemented by finite automata. Such strategies are relevant in an evolutionary context; an important instance is called Contrite Tit For Tat. In populations of players adopting such strategies, Contrite Tit For Tat survives very well -- at least as long as errors are restricted to mistakes in implementation ("the trembling hand"). However, this cooperative strategy cannot persist if mistakes in perception are included as well.

01 Jan 1997
TL;DR: In this article, a framework for constructing acidification factors relating the region of emission to the acidifying impact on its deposition areas is presented, which is also suitable for establishing similar factors for eutrophication and tropospheric ozone formation for regions outside Europe as well.
Abstract: Summary The lack of spatial differentiation in current life-cycle impact assessment (LCIA) affects the relevance of the assessed impact. This article first describes a framework for constructing factors relating the region of emission to the acidifying impact on its deposition areas. Next, these factors are established for 44 European regions with the help of the RAINS model, an integrated assessment model that combines information on regional emission levels with information on long-range atmospheric transport to estimate patterns of deposition and concentration for comparison with critical loads and thresholds for acidification, eutrophication via air; and tropospheric ozone formation. The application of the acidification factors in LCIA is very straightforward. The only additional data required, the geographical site of the emission, is generally provided by current life-cycle inventory analysis. The acidification factors add resolving power of a factor of 1,000 difference between the highest and lowest ratings, while the combined uncertainties in the RAINS model are canceled out to a large extent in the acidification factors as a result of the large number of ecosystems they cover The framework presented is also suitable for establishing similar factors for eutrophication and tropospheric ozone formation for regions outside Europe as well.