The Monographs produced by the International Agency for Research on Cancer (IARC) apply rigorous procedures for the scientific review and evaluation of carcinogenic hazards by independent experts. The Preamble to the IARC Monographs, which outlines these procedures, was updated in 2019, following recommendations of a 2018 expert Advisory Group. This article presents the key features of the updated Preamble, a major milestone that will enable IARC to take advantage of recent scientific and procedural advances made during the 12 years since (...) the last Preamble amendments. The updated Preamble formalizes important developments already being pioneered in the Monographs Programme. These developments were taken forward in a clarified and strengthened process for identifying, reviewing, evaluating and integrating evidence to identify causes of human cancer. The advancements adopted include strengthening of systematic review methodologies; greater emphasis on mechanistic evidence, based on key characteristics of carcinogens; greater consideration of quality and informativeness in the critical evaluation of epidemiological studies, including their exposure assessment methods; improved harmonization of evaluation criteria for the different evidence streams; and a single-step process of integrating evidence on cancer in humans, cancer in experimental animals and mechanisms for reaching overall evaluations. In all, the updated Preamble underpins a stronger and more transparent method for the identification of carcinogenic hazards, the essential first step in cancer prevention. (shrink)

Quelle est la nature et la fonction des sentiments dans l’activité de connaissance et, plus largement, dans l’existence humaine? Cette question, massive, n’a cessé d’inquiéter la philosophie, dont l’histoire paraît à bien des égards se confondre avec celle d’une opposition entre la lucidité de la raison et l’obscurité dangereuse des passions. Si le discours philosophique n’a jamais nié l’importance des sentiments, ni leur rôle dans l’ordonnancement général de la vie humaine, ce discours est cependant empreint d’ambiguïtés, comme l’est, déjà, le (...) statut du « cœur » dans la tripartition fonctionnelle de l’âme présentée par Platon : ni réductible à la droite raison, ni relégué dans la sphère des désirs qui nous empêchent de contempler les Idées, le sentiment est cet intermédiaire allié de la raison qui met en mouvement nos réactions morales. Cette ambiguïté se retrouve à l’âge classique, lorsque le discours philosophique découvre le fonctionnement des passions et cherche les modèles scientifiques susceptibles d’en rendre compte, hésitant entre la physiologie , la géométrie , la médecine et les sciences de la nature .En faisant de l’affectivité l’une des structures fondamentales de l’existence, la phénoménologie a replacé au centre du questionnement philosophique la problématique des sentiments. Mais comment décrire ces expériences singulières – celle de l’amour, de l’angoisse, du désespoir ou de la joie – sans les confondre avec des objets? Comment donner du sens aux affects sans adopter ce point de vue surplombant des sciences de la nature, qui confond le discours des causes et celui des raisons? Comment, en d’autres termes, continuer à parler des sentiments de manière raisonnée, tout en reconnaissant que les sentiments nous font autant que nous les connaissons – tout en continuant, par conséquent, à être réceptifs à leur pouvoir de nous ébranler? (shrink)

Enseignement de la morale et philosophie, qui inaugure la serie, s'inscrit dans le cadre d'un effort de valorisation de l'enseignement de la morale et de reflexion sur la place fondamentale de la philosophie dans la formation morale.

SummaryRussell's vicious‐circle principle is an endeavour to express a general principle of mathematics which, as the author feels, is fundamental for mathematics. This principle, in a sense warranty of formal consistency, interdicts in some form or other the selfapplication of mathematical entities. It is shown that the VCP is a vicious‐circle fallacy; that, although it can't be given an expression which is simultaneously formal and generally valid, it is generally presupposed by mathematics as far as a consistent formalism is concerned; (...) that this paradoxical situation refers to an essentially informal and non‐mathematical domain which forms a necessary condition for mathematics, but can't exhaustively be expressed in any mathematical formalism. Finally the distinction between semantical and syntactical import and the character of negation are restated in view of these results.RésuméLe principe du cercle vicieux de Russell a, selon l'auteur, une portée générale et fondamentale en mathématiques: il interdit, sous quelque forme que ce soit, lapos;application dapos;entités mathématiques à elles‐mêmes. Ce principe est équivalent au paradoxe de Russell; on ne peut pas le formaliser sous peine de compromettre sa validite universelle, et pourtant il constitue une présupposition de tout formalisme qui veut éviter la contradiction. Cette situation paradoxale nous renvoie à un domaine essentiellement in‐formel et non‐mathématique, qui embrasse le formalisme mathématique, en constitue une condition nécessaire, mais ne peut être exprimé dans aucun formalisme dapos;une manière exhaustive. Finalement le problème logique de la négation et celui de la distinction entre les rapports sémantiques et syntactiques sont repris à la lumière de ces résultats.ZusammenfassungRussells Zirkelprinzip ist der Versuch, ein allgemeingültiges Prinzip der Mathematik auszudrücken, das, wie der Verfasser meint, von grundsätzlicher Bedeutung ist. Dieses Prinzip, das in einem gewissen Sinne die formale Widerspruchsfreiheit verbürgt, verbietet die Selbstbezüglichkeit mathematischer Entitäten. Der Artikel zeigt, dass es mit Russells Paradox äquivalent ist, und dass es eine allgemeine Voraussetzung der Mathematik als eines konsistenten Formalismus darstellt, obwohl man ihm selbst keinen zugleich allgemeingültigen und formellen Ausdruck geben kann; es wird des weiteren gezeigt, dass diese paradoxale Situation auf ein wesentlich informelles und nicht‐mathematisches Gebiet verweist, das eine notwendige Bedingung für die Mathematik darstellt, jedoch selber nicht erschöpfend im Formalismus dargestellt werden kann. Schliesslich werden a) die Unterscheidung zwischen semantischen und syntakti‐schen Beziehungen und b) die Negation im Lichte dieser Ergebnisse neu überdacht. (shrink)

In their environment, plants are continuously submitted to natural stimuli such as wind, rain, temperature changes, wounding, etc. These signals induce a cascade of events which lead to metabolic and morphogenetic responses. In this paper the different steps are described and discussed starting from the reception of the signal by a plant organ to the final morphogenetic response. In our laboratory two plants are studied: Bryonia dioica for which rubbing the internode results in reduced elongation and enhanced radial expansion and (...) Bidens pilosa for which the response occurs at distance, hence pricking the cotyledon of a plantlet induces the growth inhibition of both the hypocotyl and the axillary bud of the pricked cotyledon. Reception of the signal and transmission of the message. In Bryonia the signal is received by epidermal cells while in Bidens they are the cells adjacent to the midrib of the cotyledon which receive the mechanical signal. In both plants the message is transmitted via a wave of electric depolarization. This latter is composed of an action potential associated with a slow wave whose transmission rates are respectively 1cm s−1 and 1 mm s−1. Recent results have shown the involvement of Ca2+ in the triggering of the slow wave and the role of the H+ pump during the slow wave. Transient and fast biochemical responses. An entry of extraceilular Ca2+ into the cells and a transient increase in IP3 occur within seconds following the mechanical stimulus. At the same time, the membrane becomes more fluid, correlated with qualitative changes in phospholipids. The rapid increase in the concentration of peroxidated lipids may be correlated with ethylene biosynthesis which is stimulated after rubbing. Other parameters such as cytoplasmic pH, relative water content, hydric potential, membrane potential and modifications of K+, Mg2+-ATPase and Ca2+-ATPase activities, play a key role in the early responses induced by the traumatisms. Irreversible-biochemical responses. The mechanical stimulus performed on a Bryonia internode induces an acceleration of: i) enzymatic activities related to the lignification, ii) esterification of phenolic acids in the cell wall. Consequently the lignification process is accelerated. Storage of the information. After being received by the target cells the information can be stored during several days before being expressed. At the level of cotyledonary bud, the first message, previously stored, can be expressed or not by a second treatment. Bidens thus behaves as if it was able to “store” and to “retrieve” morphogenetic messages, using a sort of rudimentary memory. The nuclei of the bud cells of the pricked cotyledon show that these cells, initially in G2 phase, divide and then remain in the G1 phase. In Bryonia, calli derived from young stimulated internodes, keep thigmomorphogenetic characteristics during several weeks. In the last part of this paper the particularity of our plant model which permits a study of the transmission and storage of the message, is underlined. The links between the different steps induced by the stimulus are discussed. Special attention is devoted to second messengers and to the amplification of the message. (shrink)

In their environment, plants are continuously submitted to natural stimuli such as wind, rain, temperature changes, wounding, etc. These signals induce a cascade of events which lead to metabolic and morphogenetic responses.In this paper the different steps are described and discussed starting from the reception of the signal by a plant organ to the final morphogenetic response. In our laboratory two plants are studied: Bryonia dioica for which rubbing the internode results in reduced elongation and enhanced radial expansion and Bidens (...) pilosa for which the response occurs at distance, hence pricking the cotyledon of a plantlet induces the growth inhibition of both the hypocotyl and the axillary bud of the pricked cotyledon. (shrink)

In biology, the “field” concept is used in different ways. Therefore, its meaning in biology as compared to that in physics, and the relation between the conceptions of “gradient” and “field” are studied.In physics, scalar fields, vector fields and tensor fields are distinguished. In a scalar field, the variation of the scalar in space is expressed in form of a gradient. For the whole of a scalar field with its derived gradients the term “gradient-field” may be used.In biology, especially in (...) experimental embryology, the field concept is used both in a purely descriptive sense and as a means of causal analysis. To the first group belong the kinematic fields and growth fields. The kinematic field is a vector field; the growth field is generally a tensor field, but may be treated as a gradient-field in the most simple cases. In the causal analysis of development the gradient-field plays an important part, in the form of axial, superficial and spatial gradient-fields. In such a field by the combined action of the scalar and the gradients a great diversity of relations may occur. Probably, both the induction field and the organisation field belong to the class of gradient-fields.Der Feldbegriff wird in der Biologie in sehr verschiedener Weise verwendet. Es wird daher versucht, das Wesen der „biologischen Felder” in Anlehnung an die Physik zu bestimmen, und das Verhältnis zwischen den Begriffen „Gradient” und „Feld” darzustellen.In der Physik unterscheidet man Skalarfelder, Vektorfelder und Tensorfelder. Im Skalarfeld lässt sich der Wechsel der Skalargrösse im Raume durch einen Gradienten darstellen. Für die Gesamtheit eines Skalarfeldes mit seinen abgeleiteten Gradienten wird der Ausdruck „Gradientfeld” vorgeschlagen.In der Biologie, im besonderen in der Entwicklungsmechanik, wird der Feldbegriff bald in rein-beschreibendem Sinne, bald als Mittel zur kausalen Analyse verwendet. Zur ersten Gruppe gehören das Bewegungsfeld und das Wachstumsfeld. Das Bewegungsfeld ist ein Vektorfeld; das Wachstumsfeld ist im allgemeinen ein Tensorfeld, kann aber im einfachsten Falle als ein Gradientfeld betrachtet werden. In der kausalen Analyse der Entwicklungserscheinungen spielt besonders das Gradientfeld eine grosse Rolle; dabei kann es sich um ein axiales, oberflächliches oder räumliches Gradientfeld handeln. Es wird darauf hingewiesen, dass in einem Gradientfelde durch das Zusammenwirken der Skalargrösse und des Gradienten eine grosse Mannigfaltigkeit der Beziehungen auftreten kann. Auch das Induktionsfeld und das Organisationsfeld gehören vermutlich zu den Gradientfeldern. (shrink)

Selon un lieu commun, la géographie médiévale se réduirait à une vaste parenthèse ouverte entre la fin du siècle d'or de l'Empire romain et la renaissance des grandes découvertes du XV° siècle. Mais quelle réalité s'agit-il de représenter ? Car toute représentation est tributaire, non seulement de conceptions particulières, mais aussi de moyens techniques qui ont présidé à son élaboration. Dans cet article, le lien entre la réalité et ses images, qui organise habituellement l'histoire de la cartographie, sera relâché au (...) bénéfice des représentations comme un système de signes appelé à prendre sens dans une production et une réception . L'enquête médiévale révèle l'attention des contemporains à la complexité de ces relations et représentations.According to common understanding, medieval geography would be reduced to a vast parenthesis, open between the end of the golden century of the Roman Empire and the renaissance of the great discoveries of the 15th century. But what is the reality being represented ?For every representation is tributary, not only of particular conceptions, but also of the technical capacities that preceded its elaboration. In this article, the connection between reality and its images, which habitually organized the history of cartography, will be set aside for the benefit of representations as a system, of signs called to have meaning in a production and a reception . This medieval inquiry reveals the attention that contemporaries have given to the complexity of its relations and representations. (shrink)