From positivism to conventionalism: Comte,Renouvier, and Poincaré

Considered in its historical context, conventionalism is quite different from the way in which it has been caricatured in more recent philosophy of science, that is, as a conservative philosophy that allows the preservation of theories through arbitrary ad hoc stratagems. It is instead a liberal outgrowth of Comtean positivism, which broke with the Reidian interpretation of the Newtonian tradition in France and defended a role for hypotheses in the sciences. It also has roots in the social contract political philosophy of Renouvier, who explicitly drew the analogy between conventions in political life and the conventional acceptance of hypotheses in the sciences, and conceived a philosophy that permits scientists to set aside foundational worries and explore new ideas. Although Poincaré and Renouvier may have hesitated to accept certain then recent developments in mathematics and the sciences such as non-Euclidean geometries, this conservatism cannot necessarily be attributed to their conventionalism. It may instead reflect the engineering background they shared with Comte, which emphasizes practical applications. Although Renouvier and Poincaré may have seen no practical use for these new ideas, unlike Comte they did not prohibit others from pursuing them, reflecting conventionalism's more liberal attitude toward recent developments in the sciences.     

History of the Lenz–Ising Model 1950–1965: from irrelevance to relevance

This is the second in a series of three papers that charts the history of the Lenz–Ising model (commonly called just the Ising model in the physics literature) in considerable detail, from its invention in the early 1920s to its recognition as an important tool in the study of phase transitions by the late 1960s. By focusing on the development in physicists’ perception of the model’s ability to yield physical insight—in contrast to the more technical perspective in previous historical accounts, for example, Brush (Rev Modern Phys 39: 883–893, 1967) and Hoddeson et al. (Out of the Crystal Maze. Chapters from the History of Solid-State Physics. Oxford University Press, New York, pp. 489–616, 1992)—the series aims to cover and explain in depth why this model went from relative obscurity to a prominent position in modern physics, and to examine the consequences of this change. In the present paper, which is self-contained, I deal with the development from the early 1950s to the 1960s and document that this period witnessed a major change in the perception of the model: In the 1950s it was not in the cards that the model was to become a pivotal tool of theoretical physics in the following decade. In fact, I show, based upon recollections and research papers, that many of the physicists in the 1950s interested in understanding phase transitions saw the model as irrelevant for this endeavor because it oversimplifies the nature of the microscopic constituents of the physical systems exhibiting phase transitions. However, one group, Cyril Domb’s in London, held a more positive view during this decade. To bring out the basis for their view, I analyze in detail their motivation and work. In the last part of the paper I document that the model was seen as much more physically relevant in the early 1960s and examine the development that led to this change in perception. I argue that the main factor behind the change was the realization of the surprising and striking agreement between aspects of the model, notably its critical behavior, and empirical features of the physical phenomena.     

The folding process of hen lysozyme: a perspective from the ‘new view’

How a conformationally disordered polypeptide chain rapidly and efficiently achieves its well-defined native structure is still a major question in modern structural biology. Although much progress has been made towards rationalizing the principles of protein structure and dynamics, the mechanism of the folding process and the determinants of the final fold are not yet known in any detail. One protein for which folding has been studied in great detail by a combination of diverse techniques is hen lysozyme. In this article we review the present state of our knowledge of the folding process of this enzyme and focus in particular on recent experiments to probe some of its specific features. These results are then discussed in the context of the ‘new view’ of protein folding based on energy surfaces and land scapes. It is shown that a schematic energy surface for lysozyme folding, which is broadly consistent with our experimental data, begins to provide a unified model for protein folding through which experimental and theoretical ideas can be brought together.     

Current cases in which epitope mimicry is considered a component cause of autoimmune disease: Guillain-Barré syndrome

Some patients develop Guillain-Barré syndrome (GBS) after the administration of bovine gangliosides. Patients with GBS subsequent to Campylobacter jejuni enteritis frequently have IgG antibody to GM1 ganglioside. Miller Fisher syndrome (MFS), a variant of GBS, is associated with IgG antibody to GQ1b ganglioside. Molecular mimicry between GM1 and lipopolysaccharide of C. jejuni isolated from patients with GBS, and between GQ1b and C. jejuni lipopolysaccharides from patients with MFS have been demonstrated. The molecular mimicry between infectious agents and gangliosides may function in the production of anti-ganglioside antibodies. This sugar mimicry is one possible cause of the Guillain-Barré and Miller Fisher syndromes; however, unidentified host factors may contribute to the development of these syndromes.     

Problems and promises: How to tell the story of a Genome Wide Association Study?

The promise of treatments for common complex diseases (CCDs) is understood as an important force driving large scale genetics research over the last few decades. This paper considers the phenomenon of the Genome Wide Association Study (GWAS) via one high profile example, the Wellcome Trust Case Control Consortium (WTCCC). The WTCCC despite not fulfilling promises of new health interventions is still understood as an important step towards tackling CCDs clinically. The ‘sociology of expectations’ has considered many examples of failure to fulfil promises and the subsequent negative consequences including disillusionment, disappointment and disinvestment. In order to explore why some domains remain resilient in the face of apparent failure, I employ the concept of the ‘problematic’ found in the work of Giles Deleuze. This alternative theoretical framework challenges the idea that the failure to reach promised goals results in largely negative outcomes for a given field. I will argue that collective scientific action is motivated not only by hopes for the future but also by the drive to create solutions to the actual setbacks and successes which scientists encounter in their day-to-day work. I draw on eighteen interviews.     

Making more synapses: a way to store information?

Although information may be stored in the brain as changes in the strength of existing synapses, formation of new synapses has long been thought of as an additional substrate for memory storage. The identification of subcellular structural changes following learning in mammals poses a serious ‘needle-in-the-haystack’ problem. In most attempts to demonstrate structural plasticity during learning, animals have been exposed for prolonged periods to complex environments, where they are confronted with a variety of sensory, motor and spatial challenges throughout the exposure period. These environments are thought to promote several forms of learning. Repeated exposure to such environments has been shown to increase the density of spines and dendritic complexity in relevant brain structures. The number of neurons has also been reported to increase in some areas. It is not clear, however, whether the new synapses emerging from these forms of plasticity mediate specific information storage, or whether they reflect a more general sophistication of the excited parts of the network.     

Sirenids: a family of polyploid urodeles?

Riassunto I tre Sirenidi viventi hanno 46, 52 e 64 cromosomi; il corredo diS. lacertina sembra tetraploide (4n=52). Viene fatta l'ipotesi che anche i corredi delle altre due specie derivino per (allo-)poliploidia da corredi a minor numero cromosomico, come si ritrovano nelle famiglie superiori dell'Ordine.

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Research carried out through a contribution from the C.N.R.     

Three unpublished letters to Charles Darwin: the solution to a ‘geometrico-geological’ problem

While Charles Darwin wrote his Observations on South America, he often sought the advice and help of other scientists in solving specific problems. Three letters that the Cambridge geologist and mathematician William Hopkins wrote to Darwin exemplify such aid. In these letters Hopkins was able to show Darwin how he could calculate the position of the sedimentary beds on the Chonos Archipelago, which Darwin had visited. In his first letter Hopkins sent a solution, part of which eluded Darwin. Darwin's letters to Hopkins have not yet been found, but two additional letters gave Darwin the solution he was looking for.