The Evolution of Extortion in Iterated Prisoner's Dilemma Games

Iterated games are a fundamental component of economic and evolutionary game theory. They describe situations where two players interact repeatedly and have the possibility to use conditional strategies that depend on the outcome of previous interactions. In the context of evolution of cooperation, repeated games represent the mechanism of reciprocation. Recently a new class of strategies has been proposed, so called 'zero determinant strategies'. These strategies enforce a fixed linear relationship between one's own payoff and that of the other player. A subset of those strategies are 'extortioners' which ensure that any increase in the own payoff exceeds that of the other player by a fixed percentage. Here we analyze the evolutionary performance of this new class of strategies. We show that in reasonably large populations they can act as catalysts for the evolution of cooperation, similar to tit-for-tat, but they are not the stable outcome of natural selection. In very small populations, however, relative payoff differences between two players in a contest matter, and extortioners hold their ground. Extortion strategies do particularly well in co-evolutionary arms races between two distinct populations: significantly, they benefit the population which evolves at the slower rate - an instance of the so-called Red King effect. This may affect the evolution of interactions between host species and their endosymbionts.Comment: contains 4 figure

Construction and technological project of the telescopic covers hall - HESTEGO a.s.

Obsahem této diplomové práce s názvem „Stavebně technologický projekt haly teleskopických krytů – Hestego a.s.“ je stavebně – technologické řešení stavby spolu s technickým, časovým, finančním, bezpečnostním, kvalitativním, požárním a legislativním řešením vybrané stavby.The content of this thesis titled "Construction and technological project of the telescopic covers hall" is building - technological solution of building together with technical, time, financial, safety, qualitative, fire and legislative solutions of selected building.

Kapitalstruktur i norsknoterte oljeserviceselskaper : en empirisk studie av påvirkningsfaktorer i perioden 2000-2015

Målet med denne masterutredningen er å gi innsikt i underliggende faktorer for kapitalstruktur i norsknoterte oljeserviceselskaper. Utredningen etterstreber å gi et helhetlig bilde av selskapenes finansieringsatferd ved å inkludere både selskapsspesifikke og makroøkonomiske faktorer i den kvantitative tilnærmingen. I motsetning til andre tradisjonelle næringer i Norge er oljeservicebransjen utelatt i forskning tilknyttet kapitalstruktur. Samtidig er studier som undersøker både selskapsspesifikke og makroøkonomiske forhold underrepresentert i empirien. Med utgangspunkt i 65 oljeserviceselskaper avdekket vi både interessante og oppsiktsvekkende funn. Vi identifiserte fire selskapsspesifikke kjernefaktorer hvor fortegn og signifikansnivå forble konsistente, uavhengig av anvendte regresjonsmodeller. De fire kjernefaktorene og tilhørende påvirkning på gjeldsandel er; Materielle Eiendeler (+), Lønnsomhet (-), Størrelse (+) og Risiko (-). Kjernefaktorene kan sies å være karakteristiske særtrekk ved oljeservicebransjen de siste 15 årene. Det er interessant at resultatene avdekker at disse særtrekkene også har vært bestemmende for kapitalstrukturen til oljeserviceselskapene. Med utgangspunkt i tre anerkjente kapitalstrukturteorier undersøker vi hvordan teoriene egner seg til å forklare observert kapitalstruktur i norsknoterte oljeserviceselskaper. Ingen av teoriene kan sies å være helt i tråd med oppnådde resultater. Trade-Off er imidlertid den teorien som best forklarer avdekket finansieringsatferd i norsknoterte oljeserviceselskaper, og dominerer således Pecking-Order og Market Timing. Det er videre verdt å merke seg at utredningens konklusjoner er upåvirket av valget mellom bokført- og markedsbasert gjeldsandel. Regresjonsmodellene oppnår lite ekstra forklaringskraft ved å inkludere makroøkonomiske variabler. Det avdekkes imidlertid to interessante makroøkonomiske faktorer, som gir indikasjoner på at gjeldsandelen i oljeserviceselskapene er prosyklisk. Makroøkonomiske funn indikerer at gjeldsandelen øker i takt med oljepris og forventningen om fremtidig vekst i norsk økonomi. Det faktum at oljepris og gjeldsandel har en positiv sammenheng er særdeles interessant, med tanke på de sykliske forholdene oljeservicebransjen opererer under. Utredningen som helhet gir en god innsikt i dynamikken rundt kapitalstruktur i ulike selskap og nyttig kunnskap om oljeservicebransjen.nhhma

The spider fauna (Arachnida: Araneae) of abandoned sites in a quarry in Bad Deutsch-Altenburg (Austria: Lower Austria)

In einem teilweise stillgelegten Steinbruch in Bad Deutsch-Altenburg nahe Hainburg/Donau (NÖ) wurde die epigäische Spinnenfauna auf sechs Untersuchungsflächen unterschiedlichen Sukzessionsalters mittels Barberfallen in der Zeit von 27. März bis 29. Oktober 2006 untersucht. Es wurden 79 Arten mit 845 adulten Individuen aus 18 Familien gefangen. Sieben Arten kamen auf allen Untersuchungsflächen vor. 28 Arten werden in den Roten Listen Tschechiens und/oder der Slowakei in einer der Gefährdungskategorie eingestuft. Die wenig bekannte Arten Thanatus pictus L. Koch, 1881 und Xysticus embriki Kolosváry, 1935 werden genauer vorgestellt. Der Vergleich der sechs Spinnengemeinschaften des untersuchten Steinbruchs mit 16 geographisch benachbarten Spinnengemeinschaften aus dem Gebiet der Parndorfer Platte zeigt einen kontinuierlichen Sukzessionsverlauf innerhalb der Ruderalfluren von den jüngsten zur ältesten Fläche und weiter zu intakten gepflegten Trockenrasen, und über verbrachende und verbuschende Trockenrasen sowie Hecken und Gebüsch-Standorten zu natürlichenWäldern der Region.The epigeic spider fauna in a partially abandoned quarry in Bad Deutsch-Altenburg/Donau (Austria: Lower Austria) was examined. Six study sites at different stages of abandonment were sampled using pitfall traps in a period from 27 March to 29 October 2006. In total, 79 species were caught comprising 845 adult individuals from 18 families. Twenty-eight species were classified as Red list taxa according to the Red lists of the Czech Republic and/or Slovakia. The poorly-known spider species Thanatus pictus L. Koch, 1881 and Xysticus embriki Kolosváry, 1935 are presented in more detail. Comparison of the six spider assemblages in the quarry with 16 geographically adjacent spider assemblages in the area of the “Parndorfer Platte” shows a clear succession within the ruderal study sites. These begin with the most recent to the oldest site, and continue to well-managed dry grasslands, further developing to scrub grasslands and hedges, and eventually to natural forests in the region

High diversity of microplankton surrounds deep-water coral reef in the Norwegian Sea

Coral reefs that exist in the depths of the oceans are surrounded by Eukarya, Archaea and bacterial communities that may play an important role in the nutrition and health of the reef. The first interdomain community structure of planktonic organisms in seawater from a deep-water coral reef is described. Community profiling and analysis of ribosomal RNA gene sequences from a coral reef system at 350 m depth in the Norwegian Sea revealed a rich diversity of Eukarya and Bacteria and a moderate diversity of Archaea. Most sequences affiliated with marine microplankton from deep-sea to cold-surface regions, with many sequences being similar to those described in studies of mesopelagic and oxygen minimum zones. Dominant phylotypes belonged to the Alveolata (group I, II, dinoflagellates), Stramenopiles (silicoflagellates), Alphaproteobacteria (Pelagibacter ubique), Gammaproteobacteria (ARCTIC96BD-19), Bacteroidetes (Flavobacteria) and mesophilic Crenarchaeota (Nitrosopumilus maritimus). Several rare and novel members of the community fell into distinct phylogenetic groups. The inferred function of dominant community members suggested autotrophs that utilise light, ammonium or sulphide, and lifestyles based on host associations. The high diversity reflected a microplankton community structure, which is significantly different from that of microplankton collected at the same depth at a pelagic station away from reefs

Public Goods with Punishment and Abstaining in Finite and Infinite Populations

The evolution and maintenance of cooperation in human and animal societies challenges various disciplines ranging from evolutionary biology, to anthropology, social sciences and economics. In social interactions, cooperators increase the welfare of the group at some cost to themselves whereas defectors attempt to free-ride and neither provide benefits nor incur costs. The problem of cooperation becomes even more pronounced when increasing the number of interacting individuals. Punishment and voluntary participation have been identified as possible factors to support cooperation and prevent cheating. Typically, punishment behavior is unable to gain a foothold in a population, while volunteering alone can efficiently prevent deadlocks in states of mutual defection but is unable to stabilize cooperation. The combined effects of the two mechanisms have surprisingly different consequences in finite and infinite populations. Here we provide a detailed comparison of the two scenarios and demonstrate that driven by the inherent stochasticity of finite populations, the possibility to abstain from social interactions plays a pivotal role, which paves the way for the establishment of cooperation and punishment.Organismic and Evolutionary Biolog

Via Freedom to Coercion: The Emergence of Costly Punishment

In human societies, cooperative behavior in joint enterprises is often enforced through institutions that impose sanctions on defectors. Many experiments on so-called public goods games have shown that in the absence of such institutions, individuals are willing to punish defectors, even at a cost to themselves. Theoretical models confirm that social norms prescribing the punishment of uncooperative behavior are stable—once established, they prevent dissident minorities from spreading. But how can such costly punishing behavior gain a foothold in the population? A surprisingly simple model shows that if individuals have the option to stand aside and abstain from the joint endeavor, this paves the way for the emergence and establishment of cooperative behavior based on the punishment of defectors. Paradoxically, the freedom to withdraw from the common enterprise leads to enforcement of social norms. Joint enterprises that are compulsory rather than voluntary are less likely to lead to cooperation.MathematicsOrganismic and Evolutionary BiologyMathematic

Changes in the prevalence, treatment and control of hypertension in Germany? : a clinical-epidemiological study of 50.000 primary care patients

INTRODUCTION: Medical societies have developed guidelines for the detection, treatment and control of hypertension (HTN). Our analysis assessed the extent to which such guidelines were implemented in Germany in 2003 and 2001. METHODS: Using standardized clinical diagnostic and treatment appraisal forms, blood pressure levels and patient questionnaires for 55,518 participants from the cross-sectional Targets and Essential Data for Commitment of Treatment (DETECT) study (2003) were analyzed. Physician's diagnosis of hypertension (HTN(doc)) was defined as coding hypertension in the clinical appraisal questionnaire. Alternative definitions used were physician's diagnosis or the patient's self-reported diagnosis of hypertension (HTN(doc,pat)), physician's or patient's self-reported diagnosis or a BP measurement with a systolic BP≥140 mmHg and/or a diastolic BP≥90 (HTN(doc,pat,bp)) and diagnosis according to the National Health and Nutrition Examination Survey (HTN(NHANES)). The results were compared with the similar German HYDRA study to examine whether changes had occurred in diagnosis, treatment and adequate blood pressure control (BP below 140/90 mmHg) since 2001. Factors associated with pharmacotherapy and control were determined. RESULTS: The overall prevalence rate for hypertension was 35.5% according to HTN(doc) and 56.0% according to NHANES criteria. Among those defined by NHANES criteria, treatment and control rates were 56.0% and 20.3% in 2003, and these rates had improved from 55.3% and 18.0% in 2001. Significant predictors of receiving antihypertensive medication were: increasing age, female sex, obesity, previous myocardial infarction and the prevalence of comorbid conditions such as coronary heart disease (CHD), hyperlipidemia and diabetes mellitus (DM). Significant positive predictors of adequate blood pressure control were CHD and antihypertensive medication. Inadequate control was associated with increasing age, male sex and obesity. CONCLUSIONS: Rates of treated and controlled hypertension according to NHANES criteria in DETECT remained low between 2001 and 2003, although there was some minor improvement

Endozoicomonadaceae symbiont in gills of Acesta clam encodes genes for essential nutrients and polysaccharide degradation

Gammaproteobacteria from the family Endozoicomonadaceae have emerged as widespread associates of dense marine animal communities. Their abundance in coral reefs involves symbiotic relationships and possibly host nutrition. We explored functions encoded in the genome of an uncultured Endozoicomonadaceae ‘Candidatus Acestibacter aggregatus’ that lives inside gill cells of large Acesta excavata clams in deep-water coral reefs off mid-Norway. The dominance and deep branching lineage of this symbiont was confirmed using 16S rRNA gene sequencing and phylogenomic analysis from shotgun sequencing data. The 4.5 Mb genome binned in this study has a low GC content of 35% and is enriched in transposon and chaperone gene annotations indicating ongoing adaptation. Genes encoding functions potentially involved with the symbiosis include ankyrins, repeat in toxins, secretion and nutritional systems. Complete pathways were identified for the synthesis of eleven amino acids and six B-vitamins. A minimal chitinolytic machinery was indicated from a glycosyl hydrolase GH18 and a lytic polysaccharide monooxygenase LPMO10. Expression of the latter was confirmed using proteomics. Signal peptides for secretion were identified for six polysaccharide degrading enzymes, ten proteases and three lipases. Our results suggest a nutritional symbiosis fuelled by enzymatic products from extracellular degradation processes.publishedVersio