Negative Research Articles

τ-Meson in the momentum cloud chamber of the école polytechnique

Among 35 000 pictures of the double cloud chamber a t the Pic du Midi [1], we have found five posi t ive and four negat ive z-mesons decaying in flight in the naomentum chamber . All five posi t ive events are fully measurable , bu t only one of the negatives. The three o ther negat ive events are mos t p robab ly decays in flight wi th three charged secondaries and are assumed to be z-> 3~ decays. We have analyzed all the four-prong events and found two which are not z-meson decays. One identified as n chance coincidence of a negat ive t rack and the decay point of a 0~ and one which is mos t p robab ly a cascade decay of a. negaMve hyperon, ~ccording to the scheme ~ -* A ~ A ~ --> p+rc . The distance be tween the two decay points is so small t h a t the event looks like a three-body decay. Table I resumes the da ta on five posi t ive and one negat ive event : The fi~:st 9 lines of Table I give the measured values: P is the m o m e n t u m in MeV/e. A refers to the pr imary , B, C and D to the secondaries. The meaning of the angles can be seen in Fig. 1. The following lines of Table I give the calculated quant i t ies: ~ _P~ is the sum of the longitudinal m o m e n t a and E P~ the vec tor sum of the t ransverse m o m e n t a of t h e three secondaries wi th respect to the direction of the pr imary . P~ adj. is the weighted mean value of the m o m e n t u m of the p r imury and ~ P~.

Photomeson production from hydrogen

the eoeffieients A0, A~, A., exhibi t the following characterist ics. a) The cons tan t term, A0, increases rap id ly above threshold for reac t ion ( 1 ) d i r e c t l y in p ropor t ion to the meson m o m e n t u m in the e.m. s y s t e m w h i l e for reac t ion (2) the increase is m u c h slower, in p ropor t ion to the cube of the meson n lomen tum. Ao has its m a x i m u m value, for bo th reactions, m the region ot Ey ~ 300 MeV, m~d falls off rap id ly above this energy. The value of Ao for react ion (2) exceeds t h a t for reac t ion (1) for E v ~ 250 MeV. b) For react ion (1), A 1 star ts out. negat ive, has its m a x i m u m ampl i tude at E v _~. 270 MeV, and changes sig'u at Ey _~ 320 MeV. For react ion (2), A~ is small below Ev ~ 400 MeV. c) For reac t ion (1), below Ey ~ 200 MeV, A~ << A0. Above this energy , A2 is negat ive , increases in magn i tude r ap idy to a m a x i m u m value at

NOVOS ESTUDOS SÔBRE AMEBAS ENCONTRADAS EM ESGÔTO, COM REFERÊNCIA ESPECIAL A UMA ENDAMEBA (E. MOSHKOVSKII) SEMELHANTE À ENDAMOEBA HISTOLYTICA

New studies on amebae found in sewage with special reference to an ENDAMOEBA (E. MOSHKOVSKII) which similar to E. HISTOLYTICA. The authors analyse the publications issued in Russia, U.S.A. and England about an endameba (E. moshkovskii), which is morphologically similar to E.histolytica and which has been isolated from sewage and used water in those countries. The authors who, in 1948, had isolated that protozoan from digested sludge in one of the sewage treatment plants of S. Paulo, Brazil, contim:ied their studies having found this Endamoeba again in material from two other sewage treat ment plants in that city. With endameha, an ameba similar to Hartmannella genus developed in the cultures. They observed that both are cultivated in temperatures ranging from 6 to 2 C but that an optimum is reached b~tween 15 and 37"C. From digested sludge with 78.5% and 41.0% of humidity the authors isolated the Endanweba and the Hartmannella. When humidity was lowered to 9% only this last organism was found and was ·also observed in material with 7.3% humidity kt&gt;pt in the laboratory for 4 years. Although this Hartmannella resisted dessication and time it was affected in its vitality when associated with E. moshkovskii because at the end of 7 months of successive passages it disapeared from cultures. Relative anaerobiosis in the culture media seem harm the multiplication of these 2 amebae. The authors tried to inoculate guinea pigs with Endamoeba with intra-coecal culture injections, having found trophozoites on the intestinal contents only in the animais killed up to 48 hours after inoculation. The histopathological exam of fragment of coeca of the inoculated guinea pigs did not show lesions. The authors considered the fact that man can accidentally swallow cysts of E. moshkovskii and eliminate them with the stools a process which might interfere in the diagnosis of tool exams due to the impossibility of a morphological separation hetween this species and E. hislolytica. For this reason, the authors tried to isolate, from human stools that free living Endamoeba. They preserved at room temperature the cultures with material from cysts passers, because in such conditions the development of E. mosh~ovskii is satisfactory. Results have been nega tive to date. In two cases (of the 16 studies), there was growth of a free living ameba of the genus Hartmannella. The authors were ahle to exclude the hypothesis that the endameha from sewage was E. histolytica or E. ranarum. Finally, they call attention of analysts and epidemiologists to, when investigating E. histolytica from exposed material ~eep in mind the possibility of contamination. by E. moshkovskii due to its ubiquity for it has been found in well water, rivers and sewage. In such doubtfull · cases biological tests can be made because morphologically it is impossible to make a differential diagnosis between cysts and trophozoites of E. histolytica and E. moshkovskii.