1) Ce cours donne une introduction aux aspects cohomologiques de la théorie des classes caractéristiques, en particulier des classes de Chern des fibrés complexes; les méthodes et résultats sont appliqués à quelques problèmes classiques de la topologie (parallélisme sur les sphères et invariant de Hopf). Dans le premier chapitre les foncteurs cohomologiques (avec ou sans axiome de dimension) sont traités en quelque détail; les exemples essentiels pour ce cours sont la cohomologie ordinaire, la K-théorie unitaire et la cohomotopie stable. Le second chapitre donne un résumé des propriétés générales qu'on peut obtenir pour les polyèdres finis à l'aide des suites spectrales et qui fournissent, pour la K-théorie (Grothendieck-Atiyah-Hirzebruch) des relations très précises avec la cohomologie ordinaire à coefficients entiers et rationnels. Dans le troisième chapitre le lien entre cohomologie et classes de Chern des fibrés complexes est discuté (caractère de Chern et propriétés d'intégralité). Le problème de l'invariant de Hopf des applications sphériques est résolu à l'aide des opérations d'Adams.

Over the last 12 years, treatment of bleeding esophageal and gastric varices has improved considerably. By the use of new techniques and with increased experience the results of endoscopic sclerotherapy have been optimized. Acute variceal bleeding, esophageal or gastric, can now be reliably and definitively stopped using the tissue adhesive Histoacryl Blau. This is also applicable to all patients irrespective of their liver status at presentation. As expected, the mortality of acute variceal bleeders has decreased considerably, no death from bleeding occurring in the last 5 years. This has obviated the need for emergency surgery, balloon tamponade or vasopressin infusion. Using an aggressive sclerotherapy technique in the bleeding-free interval, varices of all grades can now be effectively eliminated within an average of 3 sessions covering 3-4 weeks. With the intra- cum peri-variceal injection technique not only are the visible veins eradicated, but also fibrosis of the inner esophageal wall is achieved at the same time. If careful attention is paid to certain details of the technique and instruments, and with close follow-up, patients of portal hypertension can now live well in terms of liver function, without the danger of further variceal bleeding.

We report on a new method of stent exchange using a threaded device that enables removal of the clogged stent while simultaneously maintaining the original pathway without withdrawing the endoscope. With this method stent replacement has become more reliable, safer, simpler and quicker. This technique is also suitable for removal of stents dislodged inside the duct.

Endoscopic placement of a naso-vesicular catheter was successful in 90% (45/50) of patients with cholecystolithiasis. The first 7 patients were treated by MTBE dissolution alone. Dissolution was discontinued after a maximum of 14 days, as only two patients were rendered stone free. In one patient, 3 tiny pigment stones were sucked out through the catheter, and in another inoperable patient a pigtail endoprosthesis was finally inserted into the gallbladder. In the remaining 36 patients, combined ESWL and MTBE dissolution therapy was carried out. Treatment was broken off by one patient after one week, and interrupted in another due to catheter dislodgement. After an average of 10 days with 1-9 ESWL sessions (average: 3) complete stone clearance was achieved in 60% (20/34) of patients. Fourteen of the patients who completed treatment, and the one with catheter dislodgement still have sludge in the gallbladder, which is being treated with oral bile acids. The procedure-related complication rate was 10% (3 pancreatitis, 1 cystic duct perforation and 1 guidewire impaction). The mortality rate was zero. There was no evident complication due to either ESWL or MTBE dissolution.

MathematikaVolume 31, Issue 1 p. 89-97 Research Article The p-periodicity of the groups GL (n, Os(K)) and SL(n, Os(K)) B. Bürgisser, B. Bürgisser Eidgenössische Technische Hochschule, Mathematik, ETH-Zentrum, CH-8092 Zürich, SwitzerlandSearch for more papers by this authorB. Eckmann, B. Eckmann Eidgenössische Technische Hochschule, Mathematik, ETH-Zentrum, CH-8092 Zürich, SwitzerlandSearch for more papers by this author B. Bürgisser, B. Bürgisser Eidgenössische Technische Hochschule, Mathematik, ETH-Zentrum, CH-8092 Zürich, SwitzerlandSearch for more papers by this authorB. Eckmann, B. Eckmann Eidgenössische Technische Hochschule, Mathematik, ETH-Zentrum, CH-8092 Zürich, SwitzerlandSearch for more papers by this author First published: 01 June 1984 https://doi.org/10.1112/S002557930001069XCitations: 2AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat Citing Literature Volume31, Issue1June 1984Pages 89-97 RelatedInformation

2 Lopatinski, Ya. B., Ukranian Mat. J., 5, 123-151 (1953). The proofs of Theorems 1 and 2 are based upon constructions of integral representations of solutions using techniques developed in Lopatinski's paper. In the case of Theorem 1, we also utilize the methods and results of the Calderon-Zygmund theory of singular integral operators in LP spaces. 3 See Agmon (loc. cit.) and L. Hormander, Acta. Math., 99, 225-264 (1958), where he refers to unpublished results of Agmon, Douglis, and Nirenberg and of Schechter. Hormander shows for operators and boundary operators with constant coefficients on a half-space, under homogeneity conditions, that (E2) is a n.a.s.c. for all solutions of the boundary value problem in C2- to be in- finitely differentiable up to the boundary. 4 For unbounded G, Theorem 5 contains an extension of a result of the writer for the Dirichlet problem for strongly elliptic operators (see the Compt. Rend. notes cited in reference 3). 6 The Corollary to Theorem 5 contains a strengthened form of the theorem of Schechter, M., Bull. A.M.S., 64, 371-372 (1958), which states essentially that for the Dirichlet problem on a bounded domain and with C coefficients, if N(A') = {O}, then R(A) D L2(G) n C'(G). The conclusion follows from the results of Aronszajn, N., and K. T. Smith, which have been re-produced in the Tata Institute Lectures on Elliptic Differential Equations of J. L. Lions, Bombay, 1958. between the relative homotopy group of Y mod X and the homotopy group of the inclusion map X -- Y. In addition-and perhaps more serious-the Hurewicz homomorphism 0 for maps would involve an unfamiliar dimensional displacement.