Modeling the Impacts of Climate Change on Phytogeographical Units. A Case Study of the Moesz Line

Regional climate models (RCMs) provide reliable climatic predictions for the next 90 years with high horizontal and temporal resolution. In the 21st century northward latitudinal and upward altitudinal shift of the distribution of plant species and phytogeographical units is expected. It is discussed how the modeling of phytogeographical unit can be reduced to modeling plant distributions. Predicted shift of the Moesz line is studied as case study (with three different modeling approaches) using 36 parameters of REMO regional climate data-set, ArcGIS geographic information software, and periods of 1961-1990 (reference period), 2011-2040, and 2041-2070. The disadvantages of this relatively simple climate envelope modeling (CEM) approach are then discussed and several ways of model improvement are suggested. Some statistical and artificial intelligence (AI) methods (logistic regression, cluster analysis and other clustering methods, decision tree, evolutionary algorithm, artificial neural network) are able to provide development of the model. Among them artificial neural networks (ANN) seems to be the most suitable algorithm for this purpose, which provides a black box method for distribution modeling.

A közgazdaságtan metodológiájáról és a matematikai közgazdaságtanról a Neumann-modell ürügyén

A dolgozatban a Neumann-modell lehetséges elméleti és módszertani rokonságát elemezzük annak fényében, hogy mind a neoklasszikusok, mind a klasszikus hagyományokat felélesztő neoricardiánusok a magukénak vallják. Ennek során megvizsgáljuk a klasszikus és a neoklasszikus gazdaságfelfogás, az ex post és az ex ante szemléletű modellek közötti különbségeket, és azt a forradalmi jelentőségű módszertani változást, amely a sok szempontból joggal bírálható modern matematikai közgazdaságtan kialakulásához vezetett. Összevetjük Neumann modelljét az osztrák iskola árbeszámítási elméletével, a Walras­Cassel- és a Schlesinger­Wald-féle modellekkel, illetve a Ricardo, Marx, Dmitriev, Leontief nevekkel fémjelezhető klasszikus vonulat eredményeivel. Rámutatunk arra, hogy Neumann voltaképpen az "igazságos és értelmes gazdaság" ősi ideáját öntötte kora modern fizikájában honos matematikai modell formájába. /===/ The paper investigates the potential theoretical and methodological sources of inspiration of the von Neumann model, in view of the fact that both the neoclassical and the neo-Ricardian economists claim heritage to it. In the course of that the author assesses the main differences of the classical and neoclassical, the ex post and ex ante modeling approaches. He also confronts the von Neumann model with the Walras–Cassel and the Schlesinger–Wald models, and with models worked out in the classical tradition a’la Ricardo, Marx, Dmitriev and Leontief. He concludes that the Neumann-model is, in fact, nothing but a reformulation of a very old belief in a “just and reasonable economic system” based on the modern modeling approach of contemporary physics and mathematics.

Tax morale and tax evasion: Social preferences and bounded rationality

We study a family of models of tax evasion, where a flat-rate tax finances only the provision of public goods, neglecting audits and wage differences. We focus on the comparison of two modeling approaches. The first is based on optimizing agents, who are endowed with social preferences, their utility being the sum of private consumption and moral utility. The second approach involves agents acting according to simple heuristics. We find that while we encounter the traditionally shaped Laffer-curve in the optimizing model, the heuristics models exhibit (linearly) increasing Laffercurves. This difference is related to a peculiar type of behavior emerging within the heuristics based approach: a number of agents lurk in a moral state of limbo, alternating between altruism and selfishness.

Ellátási lánc kapcsolatok modellezése = Modeling of supply chain relationships

A dolgozatban az ellátási láncokban meglévő diadikus kapcsolatok minőségét állítjuk a vizsgálatok középpontjába. Az irodalomban számtalan megközelítés ismert az ellátási lánc kapcsolatok fejlődésének leírására. Ezen fejlődési elméletek inkább elméleti szinten írják le a diadikus kapcsolatok változását, annak empirikus tesztelhetőségét nem vizsgálják. Dolgozatunkban kísérletet teszünk az ellátási lánc kapcsolatok fejlődésének empirikus vizsgálatára. Arra próbálunk választ találni, hogy az életciklus hipotézis az üzleti kapcsolatok időbeli fejlődésére alkalmazható-e. = Our paper combines two approaches using data of an internet based questionnaire and applying quantitative analysis it tests the hypothesis business relationship development in time can be described with the concept of life cycle. The concept of life cycle is widely used in business research. Among others the diffusion of innovation is described using this concept, or the concept of product life cycle just to name a few. All of these researches analyze the life cycle along a specific variable (for example the volume of sales or revenue in case of the product life cycle) which (except the last stage of the cycle, the decline) has a cumulative character resulting in the widely known specific shape of a life cycle. Consequently testing a life cycle hypothesis inevitably means the acceptance of some type cumulativity in the development.

Comparative Assessment of Climate Change Scenarios Based on Aquatic Food Web Modeling

In the years 2004 and 2005, we collected samples of phytoplankton, zooplankton, and macroinvertebrates in an artificial small pond in Budapest (Hungary). We set up a simulation model predicting the abundances of the cyclopoids, Eudiaptomus zachariasi, and Ischnura pumilio by considering only temperature and the abundance of population of the previous day. Phytoplankton abundance was simulated by considering not only temperature but the abundances of the three mentioned groups. When we ran the model with the data series of internationally accepted climate change scenarios, the different outcomes were discussed. Comparative assessment of the alternative climate change scenarios was also carried out with statistical methods.