The ‘nec plus ultra’ of precision measurement: Geodesy and the forgotten purpose of the Metre Convention

Geodesy—the determination of the size and shape of the earth—has often been the science operating at the frontier of precision in the measurement of length. Its contribution to the technologies and standards of length measurement has, however, been underestimated in the literature. That, instead, places emphasis on the on the creation and international acceptance of the metric system as a whole. By new research into the standards-in-use of the community of geodesists, I rediscover the original purpose of the Metre Convention of 1875, and show for the first time the significant influence of geodesy on the standardisation of length measurement thereafter. I emphasise the role of the coherence of the web of measurement in the context of change and improvement in standards.     

Locke’s construction of the idea of power

I explain Locke’s account of the origin of our idea of power, showing that it concerns the idea of the disposition to act or change, and that this idea is constructed out of the ideas of action or change. I also show how Locke could have modified his account to avoid Hume’s criticism and argue that his neglect to do so reflects a studied neglect of taxonomy, an ambiguity in the notion of capacity, and complications in Locke’s conception of simple ideas. A comparison of the two empiricists reveals that not only do they disagree about the role of reason in the origin of our idea of power, but they are also talking about different ideas. Within the framework of Locke’s account of the origin of the idea of power, I explain why he believes that bodies only provide us with an obscure idea of active power. I conclude by defending his insight that there is a deep connection between the ability to predict and the idea of power.     

The transcendental method from Newton to Kant

Kant’s transcendental method, as applied to natural philosophy, considers the laws of physics as conditions of the possibility of experience. A more modest transcendental project is to show how the laws of motion explicate the concepts of motion, force, and causal interaction, as conditions of the possibility of an objective account of nature. This paper argues that such a project is central to the natural philosophy of Newton, and explains some central aspects of the development of his thinking as he wrote the Principia. One guiding scientific aim was the dynamical analysis of any system of interacting bodies, and in particular our solar system; the transcendental question was, what are the conceptual prerequisites for such an analysis? More specifically, what are the conditions for determining “true motions” within such a system—for posing the question of “the frame of the system of the world” as an empirical question? A study of the development of Newton’s approach to these questions reveals surprising connections with his developing conceptions of force, causality, and the relativity of motion. It also illuminates the comparison between his use of the transcendental method and that of Euler and Kant.     

Contributions of cellular electrophysiology to the understanding of the electrocardiogram

The understanding of cardiac action potential and membrane currents has broadened the theoretical foundation and enhanced the clinical usefulness of the electrocardiogram. An improved understanding of the morphology of the electrocardiographic waveform has resulted from: correlations between Vmax of depolarization and QRS complex, plateau of the ventricular action potential and S-T segment, terminal repolarization and T-wave, from definitions of action potential differences responsible for the T-wave, and recordings of action potential alternans. Cellular electrophysiology has contributed to the understanding of certain mechanisms of cardiac standstill. Many disturbances of conduction and refractoriness associated with ventricular arrhythmias can be attributed to the following derangements at the cellular level: slowing of terminal repolarization, development of diastolic depolarization in fibers with stable resting membrane potential, after-depolarizations, currents of injury resulting from non-uniform polarization, increased dispersion of action potential durations, and co-existence of slow conduction and short premature action potentials.     

La diffraction des électrons et ses applications

Summary The diffraction of electrons, based on the theories of undulatory mechanics (Louis de Broglie), has grown now to a method of investigation into the structure of matter, complementing the analysis by X-rays and electronic microscopy.Its use is developing every day in the most heterogeneous fields: study of crystalline structures, of metallic layers, of oxidation, corrosion, adsorption, catalysis, of polishing and of the conditions of superficies, as also of lubrication and of isolated molecules, etc.The article gives some instances of the diverse applications.     

Outline of a dynamical inferential conception of the application of mathematics

We outline a framework for analyzing episodes from the history of science in which the application of mathematics plays a constitutive role in the conceptual development of empirical sciences. Our starting point is the inferential conception of the application of mathematics, recently advanced by Bueno and Colyvan (2011). We identify and discuss some systematic problems of this approach. We propose refinements of the inferential conception based on theoretical considerations and on the basis of a historical case study. We demonstrate the usefulness of the refined, dynamical inferential conception using the well-researched example of the genesis of general relativity. Specifically, we look at the collaboration of the physicist Einstein and the mathematician Grossmann in the years 1912–1913, which resulted in the jointly published “Outline of a Generalized Theory of Relativity and a Theory of Gravitation,” a precursor theory of the final theory of general relativity. In this episode, independently developed mathematical theories, the theory of differential invariants and the absolute differential calculus, were applied in the process of finding a relativistic theory of gravitation. The dynamical inferential conception not only provides a natural framework to describe and analyze this episode, but it also generates new questions and insights. We comment on the mathematical tradition on which Grossmann drew, and on his own contributions to mathematical theorizing. The dynamical inferential conception allows us to identify both the role of heuristics and of mathematical resources as well as the systematic role of problems and mistakes in the reconstruction of episodes of conceptual innovation and theory change.     

On the historical origins of the contemporary notion of incommensurability: Paul Feyerabend’s assault on conceptual conservativism

This paper investigates the historical origins of the notion of incommensurability in contemporary philosophy of science. The aim is not to establish claims of priority, but to enhance our understanding of the notion by illuminating the various issues that contributed to its development. Kuhn developed his notion of incommensurability primarily under the influence of Fleck, Polanyi, and Köhler. Feyerabend, who had developed his notion more than a decade earlier, drew directly from Duhem, who had developed a notion of incommensurability in 1906. The idea is that in the course of scientific advance, when fundamental theories change, meanings change, which can result in a new conception of the nature of reality. Feyerabend repeatedly used this notion of incommensurability to attack various forms of conceptual conservativism. These include the logical positivists’ foundational use of protocol statements, Heisenberg’s methodological principle that established results must be presupposed by all further research, attempts to separate philosophical accounts of ontology from physics, Bohr’s principle of complementarity, and logical empiricist accounts of reduction and explanation. Focusing on the function of the notion of incommensurability common to Feyerabend’s various critiques explicates Feyerabend’s early philosophy as a series of challenges to forms of conceptual conservativism.     

Tryptophan metabolites kynurenine and serotonin regulate fibroblast activation and fibrosis

Fibrosis is a pathological form of aberrant tissue repair, the complications of which account for nearly half of all deaths in the industrialized world. All tissues are susceptible to fibrosis under particular pathological sets of conditions. Though each type of fibrosis has characteristics and hallmarks specific to that particular condition, there appear to be common factors underlying fibrotic diseases. One of these ubiquitous factors is the paradigm of the activated myofibroblast in the promotion of fibrotic phenotypes. Recent research has implicated metabolic byproducts of the amino acid tryptophan, namely serotonin and kynurenines, in the pathology or potential pharmacologic therapy of fibrosis, in part through their effects on development of myofibroblast phenotypes. Here, we review literature underlying what is known mechanistically about the effects of these compounds and their respective pathways on fibrosis. Pharmacologic administration of kynurenine improves scarring outcomes in vivo likely not only through its well-characterized immunosuppressive properties but also via its demonstrated antagonism of fibroblast activation and of collagen deposition. In contrast, serotonin directly promotes activation of fibroblasts via activation of canonical TGF-β signaling, and overstimulation with serotonin leads to fibrotic outcomes in vivo. Recently discovered feedback inhibition between serotonin and kynurenine pathways also reveals more information about the cellular physiology of tryptophan metabolism and may also underlie possible paradigms for anti-fibrotic therapy. Together, understanding of the effects of tryptophan metabolism on modulation of fibrosis may lead to the development of new therapeutic avenues for treatment through exploitation of these effects.