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

G. W. Leibniz, Interrelations between Mathematics and Philosophy

Drawing on the extensive number of letters and papers published in recent years, the volume investigates the interconnections between mathematics and philosophy in Leibniz's thought