THE EFFECTS OF 2.0-Bev PROTONS IN MICE

The biological effects of proton beams of 2.0 to 2.2 Bev were studied in mice. Physical studies of particle distribution and depth dosimetry are described. Data are presented on lethal dosage measurements and studies of light element activation in tissues through proton reactions (p,pn) as determined by whole-body counting of gamma activity. (C.H.

PROGRESSIVE EPITHELIAL DYSPLASIA IN MOUSE SKIN IRRADIATED WITH 10 Mev PROTONS

Up to 6 months after proton irradiation at 600 and 1200 rad epithelial hyperplasia persisted in the exposed mouse skin. Hydropic degeneration of mandy epithelial cells occurred with intra-epithelial cyst formation with hemorrhage. Focal areas of basement membrane degenerated. Interruption of and fragmentation of underlying collagen fibers was prominent. Of interest is the paramount observation that with this degree of cellular alteration and with complete breakdown of basement membrane the epithelial cells did not invade into the dermis. This suggests that the sltered epithelial cells must actually be definitely neoplastic for true invasion to occur and that a single exposure at these doses did not alter the cells sufficiently to render then andaplastic. It is possible however that larger single doses with subsequent time interval elapse might provoke the formation of neoplastic cells. This and the effect of repeated small doses and with longer periods after irradiation before sacrifice of the animal are now being investigated. (auth

Leibniz's Infinitesimals: Their Fictionality, Their Modern Implementations, And Their Foes From Berkeley To Russell And Beyond

Many historians of the calculus deny significant continuity between infinitesimal calculus of the 17th century and 20th century developments such as Robinson's theory. Robinson's hyperreals, while providing a consistent theory of infinitesimals, require the resources of modern logic; thus many commentators are comfortable denying a historical continuity. A notable exception is Robinson himself, whose identification with the Leibnizian tradition inspired Lakatos, Laugwitz, and others to consider the history of the infinitesimal in a more favorable light. Inspite of his Leibnizian sympathies, Robinson regards Berkeley's criticisms of the infinitesimal calculus as aptly demonstrating the inconsistency of reasoning with historical infinitesimal magnitudes. We argue that Robinson, among others, overestimates the force of Berkeley's criticisms, by underestimating the mathematical and philosophical resources available to Leibniz. Leibniz's infinitesimals are fictions, not logical fictions, as Ishiguro proposed, but rather pure fictions, like imaginaries, which are not eliminable by some syncategorematic paraphrase. We argue that Leibniz's defense of infinitesimals is more firmly grounded than Berkeley's criticism thereof. We show, moreover, that Leibniz's system for differential calculus was free of logical fallacies. Our argument strengthens the conception of modern infinitesimals as a development of Leibniz's strategy of relating inassignable to assignable quantities by means of his transcendental law of homogeneity.Comment: 69 pages, 3 figure

Are Counterpossibles Epistemic?

It has been suggested that intuitions supporting the nonvacuity of counterpossibles can be explained by distinguishing an epistemic and a metaphysical reading of counterfactuals. Such an explanation must answer why we tend to neglect the distinction of the two readings. By way of an answer, I offer a generalized pattern for explaining nonvacuity intuitions by a stand-and-fall relationship to certain indicative conditionals. Then, I present reasons for doubting the proposal: nonvacuists can use the epistemic reading to turn the table against vacuists, telling apart significant from spurious intuitions. Moreover, our intuitions tend to survive even if we clear-headedly intend a metaphysical reading

Airway sizes and proportions in children quantified by a video-bronchoscopic technique

Background: A quantitative understanding of airway sizes and proportions and a reference point for comparisons are important to a bronchoscopist. The aims of this study were to measure large airway areas, and define proportions and predictors of airway size in children. Methods: A validated videobronchoscope technique was used to measure in-vivo airway cross-sectional areas (cricoid, right (RMS) and left (LMS) main stem and major lobar bronchi) of 125 children. Airway proportions were calculated as ratios of airways to cricoid areas and to endotracheal tube (ETT) areas. Mann Whitney U, T-tests, and one-way ANOVA were used for comparisons and standard univariate and backwards, stepwise multivariate regression analyses were used to define airway size predictors. Results: Airways size increased progressively with increasing age but proportions remained constant. The LMS was 21% smaller than the RMS. Gender differences in airways' size were not significant in any age group or airway site. Cricoid area related best to body length (BL): cricoid area (mm2) = 26.782 + 0.254*BL (cm) while the RMS and LMS area related best to weight: RMS area (mm2) = 23.938 + 0.394*Wt (kg) and LMS area (mm2) = 20.055 + 0.263*Wt (kg) respectively. Airways to cricoid ratios were larger than airway to ETT ratios (p=0.0001). Conclusions: The cricoid and large airways progressively increase in size but maintain constant proportional relationships to the cricoid across childhood. The cricoid area correlates with body length while the RMS and LMS are best predicted by weight. These data provide for quantitative comparisons of airway lesions

On benevolence and love of others

Hobbes is famous for his insights into the impact of man’s fear, glory and greed on war and peace, not for his views on the bearing of men’s benevolence on the commonwealth. Are Hobbesian people even capable of love of others? In the literature, we find two main answers: one view is that Hobbes ruled out the possibility of disinterested benevolence among men; the other is that Hobbes considered actions driven by genuine benevolence possible but uncommon. After reviewing in broad outlines the two above positions, this chapter seeks to demonstrate the claim that Hobbes did not consider relevant to establish if men are capable of genuine benevolence or not, because he maintained that benevolent men can be as inept as egoists in differentiating apparent and real good for themselves and their loved ones and the effect of misguided altruism on the commonwealth is as damaging as the effect of ill-advised egoism.Postprin

Of analytics and indivisibles : Hobbes on the methods of modem mathematics

SUMMARY. — This article examines Hobbes's reaction to the analytic geometry of Descartes and the "method of indivisibles " introduced by Cavalieri — the two most important mathematical methods of his day. After a brief overview of Hobbesian philosophy of mathematics, it shows that his rejection of analytic geometry is based on a conception of geometry as a general science of bodies, which has no need of algebraic or analytic methods. Hobbes's attitude toward the method of indivisibles is more complex and equivocal: he accepts the method as it is presented by Cavalieri and uses it in De Corpore, but he rejects Wallis's formulation of the method in his Arithmetica Infinitorum and other works.RÉSUMÉ. — Cet article analyse l'attitude de Hobbes à l'égard de la géométrie analytique de Descartes et de la « méthode des indivisibles » introduite par Cavalieri — les deux méthodes mathématiques les plus importantes de son temps. Après un aperçu de la philosophie hobbesienne des mathématiques, il montre que le rejet par Hobbes de la géométrie analytique se fonde sur une conception de la géométrie comme science générale des corps qui n'a pas besoin des méthodes algébriques ou analytiques. L'attitude de Hobbes à l'égard de la méthode des indivisibles est plus complexe et équivoque : il l'accepte telle qu'elle est présentée par Cavalieri, et l'emploie dans son De Corpore, mais rejette la formulation qu'en donne Wallis dans Arithmetica infinitorum et d'autres ouvrages.Jesseph Douglas. Of analytics and indivisibles : Hobbes on the methods of modem mathematics. In: Revue d'histoire des sciences, tome 46, n°2-3, 1993. pp. 153-193

Berkeley's Philosophy of Mathematics

In this first modern, critical assessment of the place of mathematics in Berkeley's philosophy and Berkeley's place in the history of mathematics, Douglas M. Jesseph provides a bold reinterpretation of Berkeley's work. Jesseph challenges the prevailing view that Berkeley's mathematical writings are peripheral to his philosophy and argues that mathematics is in fact central to his thought, developing out of his critique of abstraction. Jesseph's argument situates Berkeley's ideas within the larger historical and intellectual context of the Scientific Revolution. Jesseph begins with Berkeley's