Showing papers by "University of Catania published in 1971"

Temperature and Energy Dependence of Proton Dechanneling in Silicon

Abstract: The dechanneled fractions of protons impinging along the $〈111〉$ and $〈110〉$ axial directions of Si have been measured for ion energies between 0.3 and 1.5 MeV and for target temperatures ranging between 80 and 423 \ifmmode^\circ\else\textdegree\fi{}K. The dechanneled fraction is a linear function of the penetration depth $z$. Its dependence on beam energy $E$ and the target temperature $T$ can be described simply through the parameter $\frac{z{\ensuremath{\rho}}^{2}}{E}$, ${\ensuremath{\rho}}^{2}$ being the mean-square vibrational amplitude normal to the row. All the experimental points follow a unique linear trend if plotted vs $\frac{z{\ensuremath{\rho}}^{2}}{E}$. The dechanneled fraction for the $〈110〉$ axis is a factor of 2 lower than that for the $〈111〉$. A theoretical model has been developed to describe the dechanneling in terms of a steady increase in the transverse energy, accounting for both electronic and nuclear reduced multiple scattering. The initial transverse-energy distribution of the particle just beneath the crystal surface has been computed including the experimental angular spread, and both scatterings produced by the amorphous layers covering the surface and by the atomic string potential. The limiting transverse energy for the channeled-to-random transition has been taken from the experimental ${\ensuremath{\psi}}_{\frac{1}{2}}(T)$ values. The computed dechanneled fractions agree reasonably well with the experimental ones and justify their temperature and energy dependence. The calculated fractions differ from the experimental ones in their having an upward curvature; the significance of this disagreement is briefly discussed together with the approximations involved.

Methods for recording electrical activity of the human colon in vivo. Clinical applications.

Abstract: Electrical activity in the entire human colon in vivo was studied for the first time with the use of two original methods: recordings with extraluminal electrodes applied during various abdominal operations; and recordings with intraluminal suction electrodes reaching every part of the colon by the end-to-end method which we modified with the use of a pulley. Sixty-eight cases, some without gastrointestinal disturbances and others with various diseases of the colon, were studied. In normal subjects, electrical activity is characterized by continuous slow waves with intermittent spikes. The slow waves have a regular rhythm varying from 9 to 16 cps from subject to subject at the level of the transverse and descending colon only, while in the other parts of the colon, the slow waves are irregular. In aganglionic and in idiopathic megacolon, alterations in electrical activity were observed.

Existence theorems for an optimal control problem relative to a linear, hyperbolic partial differential equation

Abstract: Existence of solutions is proved for a minimum problem for a control system described by a linear, hyperbolic partial differential equation. The cost function is an integral depending on a distributed control.

Light curve and orbital elements of V 337 Aquilae

Abstract: From photoelectric observations of V 337 Aql a new solution is carried out. Transit at primary eclipse in disagreement with the Wright-Dugan results is found. Both Russell-Merrill and Kitamura methods of light curve solution are used. The slight period variation and the distortions of the light curve would support the idea that a mass exchange could be in act.

On an optimal control problem for a hyperbolic partial differential equation

Abstract: Existence of solutions is proved for a minimum problem for a distributed-parameter control system described by a linear, hyperbolic partial differential equation. The cost function is an integral depending on boundary controls.

Characteristics of hemagglutinins of some picodnaviruses.

Abstract: Attempts to characterize some chemical properties of the picodnaviruses RV, H-l and X 14 hemagglutinins are performed using several enzymes and reagents. The results indicate the proteinaceous nature of the viral receptors since no lipidic or glycidic moiety could be shown. Although the viral receptors proved to be resistant to proteolytic enzymes such as trypsin, chymotrypsin and papain; glutaraldehyde and p-chloromercuribenzoate fully suppressed the hemagglutinating activity of the tested picodnaviruses. The inhibitory action of p-chloromercuribenzoate was reversed by 2-mercaptoethanol in the case of RV and X 14 viruses, but not in that of H-1 virus. On the whole, the chemical properties of the picodnavirus hemagglutinins appear to be different from those of other hemagglutinating viruses. However, some similarities with the hemagglutinins of entero-, and adenoviruses are evident.

Seventh Annual Meeting of the European Association for the Study Of Diabetes Southampton, England, September 15–17, 1971 Abstacts, Part 1

Abstract: s, Part 1 Reproducibility of Borderline OGTT Data on 163 Subjects. J .P . Aboulker, A.J. Valleron, L. Papoz, M. Rathery. Ins t i tut National de La Sant~ et de la Rgcherche M@dicale, Unit6 de Reeherches Statistiques U 21, Villejuif. France. Quanti tat ive data relative to the variat ion of individual blood glucose levels during repeated OGTT are few and concern normal subjects. -163 men, 20--55 years old, with suspect 0-2 h OGTT or normal tests bu t positive glycosuria have been re-tested 2--25 weeks later by 0-5 Hrs OGTT. Both tests used a 75 g glucose load and identical procedures. Obvious diabetics and normal subjects were excluded at first OGTT. Analysis of variance for replicate OGTT, allowing for systematic and betweenindividual variation give, for fasting and 2 h blood glucose levels, residual standard deviations which measure mainly physiological imprecision of blood glucose levels and laboratory error. According to data in the literature, the ratio of residual variance to total variance is found to be constant during the 0--2 h OGTT; the greater these residual variances are, the poorer the reproducibility of OGTT is. Thus the changes observed in the allocation of the subjects into the different categories of diagnostic criteria between the first and second tests are important . Correlations between individual variations of blood glucose and other parameters show that the labili ty of OGTT depends on post-glucose OGTT levels and not significantly on age, obesity, history of diabetes in the family. -Diagnostic implications of these results are discussed, particularly in relation to the problem of early detection of diabetes. The Effect of Oral Contraceptives and Glucocorticoids on Insulin Response to intensive Islet-Cell Stimulation. P.~V. Adams, M.J. Munday, N.~V. Oakley, V. ~Vynn. Alexander Simpson Laboratory, St. l~[ary's Hospital IVied. School, London W. 2. Intravenous tolbutaraide 0.5 g and glueagon 1 mg given together 2 h after a 100 g oral glucose load stimulate massive insulin release in normal subjects (Ryan, Bibbe & Schwartz 1967). This test has been carried out on 11 young women both before and after prednisone 40 mg given in divided oral doses over the preceding 24 h; (N) & (N~-P). Both tests were repeated after at least three months on a combined oral contraceptive; (O/C) & (O/C ~-P). Compared with (N), mean glucose tolerance was slightly impaired for (O/C) and ( N + P ) tests and grossly abnormal for the (O/C§ P) test. Immunoreact ive insulin levels during the first 2 h followed the same pat te rn as plasma glucose, poorest glucose ltolerance being associated with the highest insulin vMu~s. Peak insulin response to glucagon and tolbutamide occurred at about 5 rain after injection, and was usually biphasie, with a second peak at 11 -16 min; peak insulin values QzU/ml =[= 1 SEM) were: N = 4 4 5 • 0 / C = 4 1 2 : ~ 8 1 , N ~ P = 5 8 4 ~ : 6 2 , 468 Organization Section. Abstracts Diabetologia O/C + P : 765 -494. There were marked differences between individual subjects, poor insulin responses following O/C ~P being associated with impaired glucose tolerance for the (N + P) test. Implications of these findings, with particular reference to the detection of patients unsuited to oral contraceptive use will be discussed. -Ref. : Ryan, W.G., Bibbe, A.F. & Schwartz, T.B. Lancet 1967 I,

Fission of237Np+n through a double humped fission barrier

Abstract: The subthreshold fission cross section of neutron induced fission of237Np has been measured between 20 and 60 eV with the CBNM time-of-flight spectrometer. The resonances in this energy range have been analysed with a single level shape fitting computer program. The result is interpreted in the frame of Strutinsky's theory of nuclear deformation.

In Tema Di Profilassi Medica Della Calcolosi Ossalica. Sperimentazione Clinica Di Un Nuovo Farmaco Ad Azione Polivalente Il Nefrolitin

Abstract: del globo (fig. 1). Studi personali condotti sull'incidenza percentuale delIa cakolosi ossalica in Sicilia non discord ana punto dai dati surriferiti (fig. 1 a). La nefrolitiasi ossalica colpisce elettivamente gli individui di sesso maschile di eta compresa tra i 20 ed i 60 anni (fig. 2) e costituisce in pratica il 10% di tutte Ie affezioni urinarie chirurgiche; Ia sua gravid e in rapporto allo stato flogistico ad essa concomitante, alla possibilita di una recidiva ed a un pregiudizio piii 0 meno marcato della funzionalita renale.

La prova di fissazione in vitro della triiodotironina marcata come test di funzione tiroidea

Abstract: Gli AA., dopo una disamina dei problemi metodologici e dei principi teorici su cui si basa il test di fissazionein vitro della triiodotironina marcata, espongono i risultati ottenuti in 87 soggetti eutiroidei di varia eta, in 82 tireopatici ed in 44 pazienti sottoposti a terapie di varia natura. Vengono infine esaminate le correlazioni con altri indici di funzione tiroidea. Gli AA. concludono per la particolare utilita del test specie in alcuni casi in cui poco attendibili o non eseguibili sono gli altri tests di funzione tiroidea.