The Evolutionary Robustness of Forgiveness and Cooperation

We study the evolutionary robustness of strategies in infinitely repeated prisoners' dilemma games in which players make mistakes with a small probability and are patient. The evolutionary process we consider is given by the replicator dynamics. We show that there are strategies with a uniformly large basin of attraction independently of the size of the population. Moreover, we show that those strategies forgive defections and, assuming that they are symmetric, they cooperate

Notes on a distribution, breeding and weights of birds in Mendoza and San Juan provinces

Aportes al conocimiento de la distribución, la cría y el peso de aves de las provincias de Mendoza, San Juan, Republica Argentina. Primera parte. (Aves: Phytotomidae, Mimidae, Troglodytidae, Motacillidae, Emberizidae y Fringillidae)On the basis of an important collection of skins from Mendoza and San Juan provinces, Argentina, mostly obtained by W. H. Partridge in November-December 1963, new data and taxonomic notes are provided for 12 species of passerine birds: Phytotoma rutila, Mimus patagonicus, Cistothorus platensis, Anthus correndera, Anthus hellmayri, Catamenia inornata, Embernagra platensis, Sicalis auriventris, Sicalis olivascens, Phrygilus jruticeti, Phrygilus unicolor y Carduelis magellanica. New information is provided on range distribution, breeding and body mass of the specimens. Most material is housed at the Museo Argentino de Ciencias Naturales (MACN), with additional specimens in the Museo de La Plata (MLP) and the American Museum of Natural History (AMNH)

The distribution of the subspecies of <i>Thinocorus rumicivorus</i> and <i>T. orbignyianus</i> in the provinces of San Juan and Mendoza, Argentina

The presence of <i>Thinocorus rumicivorus bolivianus</i> is confirmed, from the extreme north of Argentina to the Northwest of Mendoza, where a pair was taken during the breeding season. The geographieal distribution of <i>Thinocorus orbignyianus ingae</i> is extended further to the south, in Northwestern Mendoza, and we show that the typical subspecies ranges from the south of Argentina to the south center of that province

Aportes al conocimiento de la distribución, la cría y el peso de aves de las provincias de Mendoza y San Juan, República Argentina. Segunda parte (Aves: Falconidae, Scolopacidae, Thinocoridae, Columbidae, Psittacidae, Strigidae, Caprimulgidae, Apodidae, Furnariidae, Rhinocryptidae y Tyrannidae)

En el presente trabajo se analiza un importante lote de aves en piel de estudio, coleccionado por William H. Partridge en las provincias de San Juan y Mendoza, República Argentina, durante los meses de noviembre y diciembre de 1963. Se dan a conocer nuevos datos y notas críticas taxionómicas para 23 especies de aves: Milvago chimango, Gallinago gallinago, Attagis gayi, Metriopelia melanoptera, Metriopelia aymara, Bolborhynchus aymara, Bolborhynchus aurifrons, Speotyto cunicularia, Hydropsalis brasiliana, Aeronautes andecolus, Asthenes pyrrholeuca, Teledromas fuscus, Sublegatus modestus, Stigmatura budytoides, Pseudocolopteryx flaviventris, Pyrocephalus rubinus, Knipolegus hudsoni, Knipolegus aterrimus, Hymenops perspicillata, Myiarchus swainsoni, Pitangus sulphuratus, Empidonomus aurantioatrocristatus y Tyrannus savana. También se aporta nueva nformación sobre la distribución geográfica, la reproducción y el peso corporal de los ejemplares. La colección pertenece al Museo Argentino de Ciencias Naturales de Buenos Aires (MACN), salvo unos pocos ejemplares del Museo de La Plata (MLP).On the basis of an important collection of birds from Mendoza and San Juan provinces, Argentina, procured by William H. Partridge in November and December 1963, new data and critical taxonomic notes are provided for 23 species of birds: Milvago chimango, Gallinago gallinago, Attagis gayi, Metriopelia melanoptera, Metriopelia aymara, Bolborhynchus aymara, Bolborhynchus aurifrons, Speotyto cunicularia, Hydropsalis brasiliana, Aeronautes andecolus, Asthenes pyrrholeuca, Teledromas fuscus, Sublegatus modestus, Stigmatura budytoides, Pseudocolopteryx flaviventris, Pyrocephalus rubinus, Knipolegus hudsoni, Knipolegus aterrimus, Hymenops perspicillata, Myiarchus swainsoni, Pitangus sulphuratus, Empidonomus aurantioatrocristatus, and Tyrannus savana. New information on geographical distribution, breeding and body mass of the specimens collected is also given. Most of the material studied is housed at the Museo Argentino de Ciencias Naturales, Buenos Aires (MACN), with some additional specimens examined at the Museo de La Plata (MLP)

Notas sobre una colección de aves del Parque Nacional Lihué Calel, La Pampa, Argentina

No existe hasta el momento ningún trabajo de conjunto sobre la avifauna del Parque Nacional Lihué Calel, provincia de La Pampa, República Argentina, por esta razón, nos ha parecido interesante dar a conocer una colección de aves compuesta de 117 ejemplares pertenecientes a 30 especies colectada en 1963 por W. H. Partridge en dicho parque nacional. Se incluyen además los registros de peso del cuerpo y desarrollo de las gónadas, que fueron anotados en el campo por el colector del material, el cual se encuentra depositado en el Museo Argentino de Ciencias Naturales de Buenos Aires. Aceptado el l3 de setiembre de 1986.Notes on a collection of birds from Lihué Calel National Park, La Pampa, Argentina. Up to date there is not anything paper about Lihué Calel National Park's avifauna (La Pampa Province, Argentine Republic), for it the authors studied 117 specimens of 30 species of birds colleeted in 1963 by W. H. Partridge in that national park. Additional data about weight of the body and development of gonads registered in the field by the collector are given. The material studied is kept in the Museo Argentino de Ciencias Naturales of Buenos Aires

Strategy revision opportunities and collusion

This paper studies whether and how strategy revision opportunities affect levels of collusion in indefinitely repeated two-player games. Consistent with standard theory, we find that such opportunities do not affect strategy choices, or collusion levels, if the game is of strategic substitutes. In games of strategic complements, by contrast, revision opportunities lead to more collusion. We discuss alternative explanations for this result

Synchronization techniques to increase the utilization of artificial insemination in beef and dairy cattle

Abstract The main objective of the implementation of Artificial Insemination (AI) in cattle is to produce a sustained genetic progress in the herd. Although AI is an old reproductive biotechnology, its widespread implementation is very recent and is mainly due to the use of protocols that allows the AI without heat detection, commonly called fixed-time artificial insemination (FTAI). The development of FTAI protocols also allowed the application of AI in larger, extensively managed, herds and especially in suckled cows instead of just reducing the breeding programs to the heifers. FTAI treatments are widely used in South America, with about 2,500,000 cows inseminated in the last season in Argentina and about 6,500,000 in Brazil. This manuscript aims to present and describe several treatments available and some of the factors that may affect pregnancy rates

Activity of comet 103P/Hartley 2 at the time of the EPOXI mission fly-by

Comet 103P/Hartley~2 was observed on Nov. 1-6, 2010, coinciding with the fly-by of the space probe EPOXI. The goal was to connect the large scale phenomena observed from the ground, with those at small scale observed from the spacecraft. The comet showed strong activity correlated with the rotation of its nucleus, also observed by the spacecraft. We report here the characterization of the solid component produced by this activity, via observations of the emission in two spectral regions where only grain scattering of the solar radiation is present. We show that the grains produced by this activity had a lifetime of the order of 5 hours, compatible with the spacecraft observations of the large icy chunks. Moreover, the grains produced by one of the active regions have a very red color. This suggests an organic component mixed with the ice in the grains.Comment: 11 pages, 7 figures, Icarus in pres

The effect of Zr and Sn additions on the microstructure of Ti-Nb-Fe gum metals with high elastic admissible strain

An open challenge on structural biomaterials is to obtain low-cost Ti-alloys with high elastic admissible strength (the ratio of yield strength to modulus). To reach this goal, we designed and characterized three quaternary alloys from the Ti-Nb-Fe system with additions of Zr and Sn. The samples were solution-treated and tested under two conditions: water-quenched and aged at 450 °C. Microstructures were analyzed with aid of scanning and transmission electron microscopy. Tensile tests performed at room-temperature confirmed a remarkable yield strength of 1271 MPa with an elastic modulus close to 90 GPa among aged Ti-19Nb-2.5Fe-6Sn (wt%) samples. Solution-treated Ti-19Nb-2.5Fe-10Zr samples presented a good combination of yield-strength and elastic modulus (1027 MPa and 69 GPa, respectively), displaying an elastic admissible strength close to 1.5. Although Zr and Sn are equally distributed between matrix and precipitates, the diffusion of Nb and Fe seem to be inhibited by the presence of Sn. As a result, Sn allows higher yield-strengths and more refined secondary α-phase, while Zr has a stronger effect on reducing the elastic modulus. In the end, a materials selection chart is presented to help designers to select materials for orthopedic implants considering the elastic admissible strain and cost as major guidelines16011861195CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPNão tem2014/24449-0; 2016/22714-3; 2016/24693-3Funding: This work was supported by FAPESP (São Paulo State Research Foundation, grants numbers 2014/24449-0, 2016/22714-3 and 2016/24693-3) and CNPq (National Council for Scientific and Technological Development). The authors gratefully acknowledge Prof. Hamish Fraser for the use of experimental facilities at the Center for Electron Microscopy and Analysis (CEMAS), at the Ohio State University, USA, and thank CBMM Co. for the Nb supply. The raw/processed data required to reproduce these findings cannot be shared at this time as the data also forms part of an ongoing study. Data will be made available upon reques

Co-operation in the finitely repeated prisoner’s dilemma

More than half a century after the first experiment on the finitely repeated prisoner’s dilemma, evidence on whether cooperation decreases with experience–as suggested by backward induction–remains inconclusive. This paper provides a meta-analysis of prior experimental research and reports the results of a new experiment to elucidate how cooperation varies with the environment in this canonical game. We describe forces that affect initial play (formation of cooperation) and unraveling (breakdown of cooperation). First, contrary to the backward induction prediction, the parameters of the repeated game have a significant effect on initial cooperation. We identify how these parameters impact the value of cooperation–as captured by the size of the basin of attraction of Always Defect–to account for an important part of this effect. Second, despite these initial differences, the evolution of behavior is consistent with the unraveling logic of backward induction for all parameter combinations. Importantly, despite the seemingly contradictory results across studies, this paper establishes a systematic pattern of behavior: subjects converge to use threshold strategies that conditionally cooperate until a threshold round; and conditional on establishing cooperation, the first defection round moves earlier with experience. Simulation results generated from a learning model estimated at the subject level provide insights into the long-term dynamics and the forces that slow down the unraveling of cooperation