Showing papers by "National Autonomous University of Mexico published in 1968"

Group Theory of Harmonic Oscillators and Nuclear Structure

Abstract: Publisher Summary In its simplest terms, nuclear physics concerns itself with the dynamics of n-nucleon systems, for which it is usually assumed that only two-body forces contribute; that is, the Hamiltonian has the form where s, t refer to the particle indices and Vst is an interaction derived from the data on the dynamics of the two-nucleon system. The ideal for a nuclear physicist would be to derive from this Hamiltonian all the experimental information on nuclei, such as the binding energy, energy levels, reaction cross sections, and transition probabilities. This chapter discusses the concept of fractional parentage coefficients (FPC) to the states of n particles in an harmonic oscillator (HO) potential or interacting through two-body HO forces. The chapter illustrates the way to separate the last particle or last two particles from an n-particle spin-isospin state with permutational symmetry. This leads to the concept of spin-isospin FPC. The chapter discusses the application of a realistic Hamiltonian to the translational-invariant states associated with few-nucleon problems. It also discusses clustering of n-particles states and the effect of a Serber force on a four-nucleon problem, taking states of N = 0, 1, 2 quanta. The chapter describes the influence of a two-particle spin-orbit coupling interaction on the negative parity states.

Primary carcinoma of the liver in Mexican adults

Abstract: Among 6558 autopsies performed in the General Hospital of Mexico City, only 37 (0.56%) cases of primary hepatic carcinoma were found despite an exceedingly high incidence (13.4%) of cirrhosis. Two thirds of the liver cell carcinoma coexisted with cirrhosis and 0.26% of all cases of cirrhosis were complicated by primary liver carcinoma. This low incidence of hepatic cancer has also been encountered in other Latin American countries. A tendency of liver cell carcinoma to appear predominantly in macronodular types of cirrhosis was documented, and the fact that cirrhosis in Mexico is more often micronodular is suggested as an explanation for the gap in the incidences of cirrhosis and hepatic carcinoma. It is suggested that gross classification of cancer of the liver be based on extension of the tumor within the liver rather than on appearance because of the difficulties in using uniform nomenclature and because of the surgical importance of intrahepatic distribution of the tumor.

Design of a small tidal inlet

Abstract: Estero Punta Banda on the Pacific Coast of Baja California was to be improved and stabilized as a small boat harbor by the construction of twin jetties. The throat area-tidal prism relationship at this entrance agreed with that of other inlets on sandy coasts in equilibrium. This throat area was retained in the jetty spacing. The major question to be resolved was whether to retain the entrance in its present position at the north end of the lagoon or to cut a new entrance at the south end. The former position was chosen.

Studies on the advent of ureotelism. Factors that render the hepatic arginase of the Mexican axolotl able to hydrolyse endogenous arginine.

Abstract: 1. A study was undertaken of the conditions that might operate in the synthesis and hydrolysis of arginine by axolotl liver homogenate to test a previous postulate that liver arginase of the non-metamorphosed Mexican axolotl is not able to hydrolyse arginine formed from citrulline and aspartic acid, though it can split exogenous arginine, and also that an enhanced capacity to hydrolyse endogenous arginine plays a major role in the advent of ureotelism observed during the metamorphosis of the axolotl. 2. It was found that the arginase from axolotl liver is very unstable under the conditions followed, contrary to what is observed in rat liver. 3. Axolotl arginase is able to hydrolyse endogenous arginine if preserved. 4. Mn2+ protects the enzyme and renders it able to split endogenous arginine. 5. It is suggested that the metal ion produces a change of conformation of the enzyme that, being stable, is capable of hydrolysing the amino acid, or that the new conformation is appropriate for interaction with the sites of arginine synthesis.

Calculation of the Magnetic Moment of Atomic Fluorine

Abstract: The atomic ${g}_{J}$ factors for the two levels composing the lowest term of atomic fluorine have been calculated utilizing the theory of Kambe and Van Vleck and wave functions resulting from Hartree-Fock treatments of varying accuracy. For the high-accuracy wave functions, the results of our calculation are in exact agreement with the measured $\frac{{g}_{J}({\mathrm{F}}^{19}; ^{2}P_{\frac{3}{2}})}{{g}_{J}({\mathrm{H}}^{1}; ^{2}S_{\frac{1}{2}})}=\frac{2}{3}\ensuremath{-}(497\ifmmode\pm\else\textpm\fi{}1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$, to within the experimental error. The contribution to ${g}_{J}({\mathrm{F}}^{19}; ^{2}P_{\frac{3}{2}})$ arising from the Breit interaction is found to amount to 49\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}6}$. This sizeable contribution, and the excellent agreement obtained, substantiate the validity of the theory and, in particular, of the Breit interaction to the order of ${\ensuremath{\alpha}}^{2}$. For the upper level, the value ${g}_{J}({\mathrm{F}}^{19}; ^{2}P_{\frac{1}{2}})=\frac{2}{3}\ensuremath{-}(1072\ifmmode\pm\else\textpm\fi{}2)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}6}$ is obtained. For this, no experimental test of adequate sensitivity has been made.