The Late Quaternary extinction of megafauna has been a ‘‘hot topic’’ of research and debate since at least the time of Darwin (who discussed it in the Origin), but especially since the 1960s when Paul Martin ignited the debate with his theory of prehistoric overkill. The topic has had increasing exposure over the past ten years because of the relevance of this, the most recent palaeontological ...

Pyrrolyl squaraines, both dyes and polymers, were first reported in 1965 and since then a fascinating body of work has been produced investigating the chemistry of these interesting molecules. A major aspect of these molecules that makes them so appealing to those researchers who have contributed to this field over the last 50 years is their chemical versatility. In this review, subjects, such ...

This year marks the 50th anniversary of the discovery of dopamine as a putative independent neurotransmitter in the nervous system. The amine 3-hydroxytyramine (‘dopamine’) had earlier been identified as an intermediary in the synthesis of noradrenaline and adrenaline from tyrosine. In 1957,ArvidCarlsson,MargitLindqvist,TorMagnussonand BertilWaldeck, inLund [1,2], andKathleenMontagu,working in ...

The history of radiocarbon dating through the 20th century is presented, focusing on the work of Willard F. Libby, who introduced radiocarbon dating in 1949, and its application during the following 50 years. Topics include an explanation of radiocarbon dating, by which the age of organic matter can be determined; difficulties Libby encountered in developing processes for accurate measurements;...

This paper studies the announcement returns to diversifying mergers from 1950 to 2002. It is widely believed that corporate diversification destroys value, but we find that combined (bidder + target) announcement returns were significantly positive for diversifying mergers throughout the period. The return from diversifying mergers fell after the 1970s, consistent with the view that investors s...

An assessment of some aspects of the impact of quantum mechanics on chemistry will be attempted, with emphasis on the different ways it has had an important influence. These include a change in the chemists' vocabulary, his way of looking at molecules and reactions, the instruments and methods he uses, the psychological satisfaction he gets from his subject, the procedures he uses to describe a...

Maximal monotone operator theory is about to turn (or just has turned) fifty. I intend to briefly survey the history of the subject. I shall try to explain why maximal monotone operators are both interesting and important—culminating with a description of the remarkable progress made during the past decade.

The first technical issue of the Boletin de la Oficina Sanitaria Panamericana, published in 1922, was dedicated to leprosy. During the intervening SO years considerable progress has been made in understanding the disease, leading to benefit for the patient and more effective control. Movement away from institutionalization and toward ambulatory care for patients plus new and effective treatment...

Studies using open-ended response modes to elicit probabilistic beliefs have sometimes found an elevated frequency (or blip) at 50 in their response distributions. Our previous research suggests that this is caused by intrusion of the phrase "fifty-fifty," which represents epistemic uncertainty, rather than a true numeric probability of 50%. Such inappropriate responses pose a problem for decis...