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A common problem of non-enzymatic artificial replicator systems is product inhibition leading to parabolic instead of exponential amplification. Exponential chemical replication of oligonucleotides was recently achieved by an iter- ative, stepwise procedure, which employs the surface of a solid support, and which was called SPREAD (i.Surface Promoted Replication and Exponential Amplification of DNA analoguesli). We here report on theoretical insights into the design of an autonomous variant of the SPREAD procedure. The corresponding program simulates a given set of chemical reactions coupled to a chromatographic process where the chromatographic column is treated as a se- ries of connected cells. The crucial step is a template-directed reaction occurring at the surface: Thus, we assumed that two parabolic replicators compete for their building blocks in the chromatographic column. A simplified, semi-analytic treatment confirms that competing parabolic replicators that spread on mineral surfaces are amenable for Darwinian selection under a wide range of parameter values. We believe that the chromatographized replicator model is relevant to the origin of life on earth. The chromatographic column is equivalent to a tunnel or a riverbed of minerals in which water containing the resources is continuously running through.

Absztrakt:

Két kísérlet eredményeit mutatjuk be a cikkben. A kísérleteket az Elliot Aronson által kifejlesztett mozaikmódszerrel végeztük abból a célból, hogy kimutassuk a kooperációs tanulási módszer előnyeit az osztályteremben zajló tanulás során. A kooperáció evolúciós biológiai és szociálpszichológiai értelmezése alapján azt vártuk, hogy az együttműködés pozitív hatást gyakorol a tanulók egyes szociális készségeinek alakulására. Kiderült, hogy ez a várakozás csak bizonyos feltételek között igaz. A nyolcadikos, iskolaváltás előtt álló diákok kevésbé hajlanak a kooperációra, s a biológia mint tantárgy is kevéssé alkalmas a módszer alkalmazására. Fiatalabb korú diákok és diszkurzív tantárgy esetén viszont a kooperatív módszer alkalmazása előnyös.

Összefoglaló. Az eddigi összes világjárványt olyan zoonotikus kórokozók, vírusok vagy baktériumok okozták, amelyek könnyen tudnak emberről emberre is terjedni. Minden egyes felbukkanó fertőzés egészségügyi, társadalmi és gazdasági költségeket von maga után. Az országhatárok nem tudják hatékonyan korlátozni a betegségek terjedését. Az eddigi trendek alapján jóval több mint félmillióféle, zömmel teljesen ismeretlen vírus lehet képes embereket megfertőzni. Az ember által letarolt vagy urbanizált területeken olyan állatfajok lesznek dominánsok, amelyek kifejezetten jó kórokozó-fenntartók. A hangsúlyt mostantól kezdve a megelőzésére kell helyezni, melynek a feltételei végrehajtható tervek formájában adottak. A hatékony megelőzés költséges, de jóval olcsóbb, mint egy világjárvány gazdasági következményeit viselni.

Summary. So far, all pandemics have been caused by zoonotic pathogens, viruses or bacteria that could easily spread from human to human. Emerging infectious diseases entail huge costs for the health system, as well as for society and economy in general. Experience tells us that national borders are insufficient to prohibit the spread of infectious diseases. Extrapolation from current trends suggests that the number of largely unknown virus species able to infect humans is well over half a million. Overall, we seem to lack knowledge about 90% of the pathogens of the world. A striking experience is that pathogens can jump hosts based on their standing genetic variation and phenotypic plasticity. Mutations tend to follow later and lead to evolutionary finetuning of the pathogenic lifecycle. Human activity has contributed a great deal to the current dangerous rise of emerging infectious diseases. Climate change induces migration, biological invasions, and a higher incidence of the encounter of species with potential pathogens. Invading species tend to disrupt local ecosystems, resulting in lower biodiversity and higher susceptibility to disease of the remaining endemic species as well as the agriculturally important, domestic plant and animal populations. Habitats devastated by human activity as well urban areas will be dominated by species (such as rodents) that can harbour several potential and actual pathogens. Urbanization is a major risk factor for several reasons, including the elevated temperature in cities that contributes to the increase in pathogen survival during winter and the high population density and consequential contact rate of the local human population. Globalization adds to the security hazard posed by pathogens. From now on, emphasis should be put on the prevention of pandemics, for which we have executable plans. One such plan is the DAMA protocol (Document, Assess, Monitor, Act). We must document the occurrence of potential pathogens in candidate host species. Then we assess the threat level associated with identified potential pathogens, followed by a systematic monitoring of the most dangerous pathogens, looking for early signs of potential outbreaks. Action means advice by experts on possible preventive measures by experts and their evaluation and execution by decision makers. Similar ecological diagnostics seem possible for biological invasions in general. Efficient prevention is costly, but considerably less so than bearing the economic consequences of pandemics by (re-)emerging infectious diseases.