Fresnel's laws,ceteris paribus

This article is about structural realism, historical continuity, laws of nature, and ceteris paribus clauses. Fresnel's Laws of optics support Structural Realism because they are a scientific structure that has survived theory change. However, the history of Fresnel's Laws which has been depicted in debates over realism since the 1980s is badly distorted. Specifically, claims that J. C. Maxwell or his followers believed in an ontologically-subsistent electromagnetic field, and gave up the aether, before Einstein's annus mirabilis in 1905 are indefensible. Related claims that Maxwell himself did not believe in a luminiferous aether are also indefensible. This paper corrects the record. In order to trace Fresnel's Laws across significant ontological changes, they must be followed past Einstein into modern physics and nonlinear optics. I develop the philosophical implications of a more accurate history, and analyze Fresnel's Laws' historical trajectory in terms of dynamic ceteris paribus clauses. Structuralists have not embraced ceteris paribus laws, but they continue to point to Fresnel's Laws to resist anti-realist arguments from theory change. Fresnel's Laws fit the standard definition of a ceteris paribus law as a law applicable only in particular circumstances. Realists who appeal to the historical continuity of Fresnel's Laws to combat anti-realists must incorporate ceteris paribus laws into their metaphysics.     

Establishment of intestinal homeostasis during the neonatal period

The intestinal mucosa faces the challenge of regulating the balance between immune tolerance towards commensal bacteria, environmental stimuli and food antigens on the one hand, and induction of efficient immune responses against invading pathogens on the other hand. This regulatory task is of critical importance to prevent inappropriate immune activation that may otherwise lead to chronic inflammation, tissue disruption and organ dysfunction. The most striking example for the efficacy of the adaptive nature of the intestinal mucosa is birth. Whereas the body surfaces are protected from environmental and microbial exposure during fetal life, bacterial colonization and contact with potent immunostimulatory substances start immediately after birth. In the present review, we summarize the current knowledge on the mechanisms underlying the transition of the intestinal mucosa during the neonatal period leading to the establishment of a stable, life-long host–microbial homeostasis. The environmental exposure and microbial colonization during the neonatal period, and also the influence of maternal milk on the immune protection of the mucosa and the role of antimicrobial peptides, are described. We further highlight the molecular mechanisms of innate immune tolerance in neonatal intestinal epithelium. Finally, we link the described immunoregulatory mechanisms to the increased susceptibility to inflammatory and infectious diseases during the neonatal period.     

The rise of cryptographic metaphors in Boyle and their use for the mechanical philosophy

This paper tracks the development of Boyle's conception of the natural world in terms of the popular “book of nature” trope. Boyle initially spoke of the creatures and phenomena of nature in a spiritual and moral register, as emblems of divine purpose, but gradually shifted from this ideographic view to an alphabetical account, which at times became posed in explicitly cryptographic terms. I explain this transition toward cryptographic metaphors in terms of Boyle's social and intellectual milieu and their concordance with the reductive and conjectural character of the mechanical philosophical program.     

Fibroblast-to-myofibroblast transition in bronchial asthma

Bronchial asthma is a chronic inflammatory disease in which bronchial wall remodelling plays a significant role. This phenomenon is related to enhanced proliferation of airway smooth muscle cells, elevated extracellular matrix protein secretion and an increased number of myofibroblasts. Phenotypic fibroblast-to-myofibroblast transition represents one of the primary mechanisms by which myofibroblasts arise in fibrotic lung tissue. Fibroblast-to-myofibroblast transition requires a combination of several types of factors, the most important of which are divided into humoural and mechanical factors, as well as certain extracellular matrix proteins. Despite intensive research on the nature of this process, its underlying mechanisms during bronchial airway wall remodelling in asthma are not yet fully clarified. This review focuses on what is known about the nature of fibroblast-to-myofibroblast transition in asthma. We aim to consider possible mechanisms and conditions that may play an important role in fibroblast-to-myofibroblast transition but have not yet been discussed in this context. Recent studies have shown that some inherent and previously undescribed features of fibroblasts can also play a significant role in fibroblast-to-myofibroblast transition. Differences observed between asthmatic and non-asthmatic bronchial fibroblasts (e.g., response to transforming growth factor β, cell shape, elasticity, and protein expression profile) may have a crucial influence on this phenomenon. An accurate understanding and recognition of all factors affecting fibroblast-to-myofibroblast transition might provide an opportunity to discover efficient methods of counteracting this phenomenon.     

Taking times out: Tense logic as a theory of time

Ulrich Meyer’s book The Nature of Time uses tense logic to argue for a ‘modal’ view of time, which replaces substantial times (as in Newton’s Absolute Time) with ‘ersatz times’ constructed using conceptually basic tense operators. He also argues against Bertrand Russell’s relationist theory, in which times are classes of events, and against the idea that relativity compels the integration of time and space (called by Meyer the Inseparability Argument). I find fault with each of these negative arguments, as well as with Meyer’s purported reconstruction of empty spacetime from tense operators and substantial spatial points. I suggest that Meyer’s positive project is best conceived as an elimination of time in the mode of Julian Barbour's The End of Time.     

Three concepts of causation in Newton

In this paper, I argue that recent debates about Newton’s attitude toward action at a distance have been hampered by a lack of conceptual clarity. To clarify the metaphysical background of the debates, I distinguish three kinds of causes within Newton’s work: mechanical, dynamical, and substantial causes. This threefold distinction enables us to recognize that although Newton clearly regards gravity as an impressed force that operates across vast distances, he denies that this commitment requires him to think that some substance acts at a distance on another substance. (Dynamical causation is distinct from substantial causation.) Newton’s denial of substantial action at a distance may strike his interpreters as questionable, so I provide an argument to show that it is in fact acceptable.     

Peace with nature,or plants as indicators to the loss of humanity

Summary 1)Peace with nature means that human relations with other beings are controlled constitutionally within a community to which not only mankind belongs. Constitutionally restricted and in this sense non-violent, human domination is legitimate. 2) What we are allowed to do depends on who we are. Mankind is the species in which nature emerges to express herself in language, art and reason, and in doing so she moves herself forward with us. 3) How we should relate ourselves to nature also depends on our understanding of nature. Nature basically is acting nature, or creative power, and in this sense equally is the nature of the beings of nature. 4) Some artifacts are more natural and correspond to peace with nature better than others which are unnatural and violate peace with nature. Also in our fellow world, and even apart from man's influence, nature is whatought to be. 5) The technologically less advanced countries should not repeat the mistakes of the industrialized countries. The traditional pattern of industrial economy cannot be generalized to all peoples and violates peace with nature. 6) Plants are not only most sensitive indicators to environmental pollution but to the loss of humanity as well.     

Photolyse ultraviolette et photoréactivation des bactéries — Aspects de dépolymérisation et repolymérisation des acides nucléiques bactériens

Summary Electrophoretic analysis of bacterial substance proves the departure, from UV irradiated microbes screened from light for a certain time, of substances which were responsible for increasing the charge density by surface unit during the first moments which follow the irradiation by UV rays. Spectrophotometric analysis of liquids having contained these bacilli proves concommitantly the diffusion of those substances from the bacterial substance to the aqueous phase and reveals their nature. The photoreactivity which is possible during the first moments following the UV irradiation of bacilli, due to the presence of the fragments of depolymerisation of nucleic acid macromolecule in the bacterial substance, becomes impossible after the departure (diffusion) of those fragments to the aqueous phase. These observations seem to show that the phenomenon of photo-reactivity is connected with the repolymerisation of the macromolecule primitively divided of desoxyribonucleic acid.     

The Diels-Alder reaction and biopolymer catalysis

The Diels-Alder reaction provides a general and facile entry for the synthesis of six-membered cyclic structures. Consequently, it has been used extensively by organic chemists for the construction of complex compounds with pharmaceutical potential. Nature also appears to have utilized this reaction in the biosynthesis of several secondary metabolites. Given its utility, various catalysts have been discovered for the reaction ranging from simple Lewis acidic transition metals to complex catalytic antibodies. More recently, modified RNA has also been shown to be an effective Diels-Alderase with a highly specific active site. The RNA Diels-Alderase activity was also shown to be absolutely dependent on the nature of the base modification and the presence of cupric ion. Together, these results suggest that this RNA Diels-Alderase achieves a portion of its rate acceleration through Lewis acid catalysis, a different mechanistic mode than similar protein Diels-Alderases. The notion that RNA can accelerate reactions through Lewis acid catalysis suggests that modified RNA may serve as a tunable catalytic platform for the creation of structurally diverse compounds using a variety of powerful chemical transformations. Received 28 December 1998; received after revision 25 February 1999; accepted 26 February 1999     

Disadvantages of acid precipitation of proteins during the assay of blood glucose by the enzymatic glucose oxidase-peroxidase system]

In the enzymatic procedure for blood sugar by means of glucose oxidase, acid protein precipitation of blood by perchloric acid or trichloracetic acid liberated oxidizing substances, which enhanced the coloration density in oxidizing the reduced chromogen of the reaction mixture, independently of the hydrogen peroxide generated from glucose, and would give false high values of glycemia, if additional precautions had not been taken. These substances, increasing considerably with times and temperature of blood conservation, would be of peroxide nature, and would accumulate in red blood cells during their exposure to air.     

Phytotoxins and their involvement in plant diseases. Introduction

Bacterial and fungal plant pathogens are known to produce diffusible toxins in infected plants. These phytotoxins are harmful to plants in very low concentrations, and many reproduce at least some of the symptoms of the relevant bacterial or fungal disease. Several phytotoxins have been shown to be involved in pathogenesis. Recent years have seen substantial progress in our knowledge about the nature, structure and mode of action of phytotoxins, and this is briefly reviewed. Finally, possible applications in fields other than plant pathology are mentioned.The Editors wish to thank Prof. A. Ballio and Prof. A. Graniti for coordinating this multi-author review.     

Zur Chemotherapie der Tuberkulose

Summary The paper deals with recent advances in chemotherapy of tuberculosis. In view of the fact that chemical analysis has shown the lipoid nature of tubercle bacilli and in view of the favorable therapeutic results obtained by treating leprosy with chaulmoogra-acids, the leading idea of many authors was to synthetize lipoidsoluble substances in order to affect the growth of tubercle bacilli. However, the finding that water-soluble substances as Promin inhibit the growth of the microorganisms showed that the idea to use exclusively fatsoluble substances was not necessarily right. Although the therapeutic effects of Promin are not yet particularly encouraging, the experiments made with this substances are useful as they indicate a new direction for research in chemotherapy of tuberculosis. Some of our own experiments with diaminodiphenylsulphone-derivatives are described.     

Effets de la 2-mercaptopropionyl-glycine sur la différenciation de l'œuf d'oursin

Summary 2-Mercaptopropionyl-glycine (Thiola) exerted a strong animalizing action on the development of the sea urchin,Paracentrotus lividus. The action of Thiola on the synthesis of superficial and cortical cellular structures newly synthesized during the segmentation is suggested. These changes may alter the circulation of morphogenetic substances between blastomeres.     

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.     

Der Einfluß der Nebenniere auf die Kreislaufwirkung des Adrenalins

Summary Traces of nor-adrenaline restore the vascular action of adrenaline altered in epinephrectomized dogs to the reaction of the normal animal. Therefore it is claimed that the adrenals discharge one or several substances into the blood stream, which are necessary for the usual peripheral vascular action of adrenaline. Further investigations are in progress.     

The objectivity of scientific measures

The fundamental constants of nature, as presented by modern science, can be conceived as natural measures of the universe. In comparison, the standards of the International System of Units, including the kilogram and the meter, are mind-made and hand-crafted to meet the demands of human life. In this paper, the gap between the natural and the conventional is squeezed from two directions. In the first place, we come to understand why the metric measures were originally conceived, by the best of scientists, as being “taken from nature” and “in no way arbitrary”. The kilogram of yesteryear was anchored in yesteryear's science and is reasonably considered natural with respect to that science. We also review a contemporary debate amongst physicists that questions whether any quantity, being necessarily written with units, can be truly fundamental. Modern notions of a fundamental constant are put under the spotlight; the kilogram emerges as bound up with contemporary science today as ever it was. In the picture being painted here, our measures are drawn as dynamic entities, epistemic tools that develop hand-in-hand with the rest of science, and whose significance goes much further than a metal artefact dangled from an abstract number line.     

Shifting ontologies, changing classifications: plant materials from 1700 to 1830

This paper studies European chemists’ shifting ontologies of materials by comparing the ways in which they classified materials. The focus is on plant materials, their different identities, and the changing ways chemists sorted out and ordered plant materials in the eighteenth and early nineteenth centuries. The main goals of the paper are to follow the development of plant materials from ordinary, everyday materials and commodities in the early eighteenth century to purified carbon compounds and organic substances familiar only to experts in the 1830s, and to reconstruct chemists’ ways of classifying these objects in different practical and intellectual contexts.The study of changes in European chemists’ ways of classifying plant materials over more than a century brings to the foreground a trajectory of ontological shifts that is ‘punctuated’ in the 1750s, the 1790s, and the 1830s. Early eighteenth-century plant materials, which were commodities of the apothecary trade and other arts and crafts, were elevated epistemically as compound components or ‘proximate principles’ of plants in the 1750s, reduced to organic compounds in the 1790s, and replaced by carbon compounds in the 1830s. The last, third transformation of the epistemic constitution of materials and the mode of their classification was accompanied by a deep transformation of the material culture of plant chemistry. After the late 1830s, many of the eighteenth-century vegetable commodities disappeared from chemists’ agenda or were split into different substances individuated and identified in new ways. Coal tar products, and new organic artefacts containing chlorine or bromine, entered the chemical laboratory in the 1820s and became fused with the purified rest of the previous plant and animal substances. The material objects of the new culture of organic chemistry became detached from the materials applied in the extant arts and crafts. It was only in the late 1850s, with the rise of the synthetic dye industry, that a great number of these laboratory substances became involved in industrial production.     

Zur Frage des Angriffspunktes des Thiouracil

Summary The mechanism of action of thiouracil and thiourea was investigated on Xenopus tadpoles. Both substances are able to stop metamorphotic changes if administered early enough. Characteristic disturbances occur in the epithelium of the thyroid follicles after only 24 hours. The action of these substances over a period of several weeks may lead to goitre. In the pituitary anterior lobe, on the other hand, the same characteristic changes take place in the basophilic cells as after thyroidectomy. The thyroid structure of hypophysectomised tadpoles corresponds to that of untreated hypophysectomised animals. Thiourea and thiouracil do not inhibit the thyroxine effect on thyroidectomised and hypophysectomised tadpoles. These findings indicate that the point of attack of thiouracil and thiourea lies in the follicular epithelium of the thyroid, and thus supportAstwood's hypothesis.     

Properties and modes of action of specific and non-specific phospholipid transfer proteins

We have described the mode of action of the phosphatidylcholine transfer protein (PC-TP), the phosphatidylinositol transfer protein (PI-TP) and the non-specific lipid transfer protein (nsL-TP) isolated from bovine and rat tissues. PC-TP and PI-TP specifically bind one phospholipid molecule to be carried between membranes. PC-TP, and most likely PI-TP as well, have independent binding sites for the sn-1- and sn-2-fatty acyl chains. These sites have different properties, which may explain the ability of PC-TP and PI-TP to discriminate between positional phospholipid isomers. nsL-TP, which is identical to sterol carrier protein 2, transfers all common phospholipids, cholesterol and oxysterol derivatives between membranes. This protein is very efficient in mediating a net mass transfer of lipids to lipid-deficient membranes. Models for its mode of action, which is clearly different from that of PC-TP and PI-TP, are presented.