Partial differential matrix equations for the inverse problem of scattering theory

in Journal of Mathematical Physics (1976), 17

Sufficient conditions for the existence of a continuous translation operator are found in the case of a system of differential equations in which the matrix potential has the singularity of the ... [more ▼]

Sufficient conditions for the existence of a continuous translation operator are found in the case of a system of differential equations in which the matrix potential has the singularity of the centripetal term. The sufficient conditions are found in terms of moments of the nuclear potential. The method used employs the Riemann Green's function. Threshold energies introduce a threshold energy dependence into the translation kernel and lead to a requirement of an exponential decrease for terms of the matrix potential. [less ▲]

L'école et les textes

in Revue de la Direction Générale de l’Organisation des Etudes (1976)

The irresistible need for educational research

Conference (1976, June)

The function of research is to perfect the tools of education and to manufacture new ones. Research opens up perspectives and informs teachers. The whole of the education system and all its components ... [more ▼]

The function of research is to perfect the tools of education and to manufacture new ones. Research opens up perspectives and informs teachers. The whole of the education system and all its components should be investigated if research is to be comprehensive and successful. Highly qualified teams of researchers are essential, bringing a variety of interests, knowledge, and points of view. Education is a human venture and also a realm of contingencies; it is important that educational research take into account the teacher's cultural background, intellectual limitations, needs, frustrations, and the real problems faced in the classroom. Full understanding and communication between researchers and teachers must exist if change and action are to result from educational exploration, evaluation, and future planning. (JD) [less ▲]

On the evolution of ionized gas around hot stars

in Astrophysics & Space Science (1976), 41

The initial evolution of a uniform H II region around a star of 36 solar masses is described. The general equations of the problem are solved numerically by a finite-difference method. Forbidden-line ... [more ▼]

The initial evolution of a uniform H II region around a star of 36 solar masses is described. The general equations of the problem are solved numerically by a finite-difference method. Forbidden-line emission by ions of C, N, O, and Ne is taken into account. [less ▲]

Fate of thiazolidine ring during fragmentation of penicillin by exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61

in Nature (1976), 260(5550), 451-454

LIKE various beta-lactamases, acylases and esterases1, the exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61 degrades benzylpenicillin and other beta-lactam antibiotics2-4. The R61 enzyme ... [more ▼]

LIKE various beta-lactamases, acylases and esterases1, the exocellular DD-carboxypeptidase-transpeptidase of Streptomyces R61 degrades benzylpenicillin and other beta-lactam antibiotics2-4. The R61 enzyme, however, markedly differs from the other penicillin-degrading enzymes in causing fragmentation of the penicillin nucleus. By using 8-14C-benzylpenicillin (benzyl labelled) as substrate, one of the fragments produced was shown to be 14C-phenylacetylglycine5. The reaction with the R61 enzyme is also peculiar in that it is a slow process. This is because of the long half life of the stoichiometnc complex transitorily formed between the antibiotic and the enzyme. Thus, for example, the value of the half life for the complex formed with benzylpenicillin is 80 min in 10 mM phosphate buffer (pH 7.0) and at 37 °C. As breakdown of the complex proceeds, however, phenylacetylglycine (when benzylpenicillin is used as substrate) is released and the enzyme concomitantly recovers its ability to bind penicillin. We have now characterised the fragment (hereby designated as the Y product) arising from the thiazolidine ring of penicillin as a result of the fragmentation of the antibiotic molecule by the R61 enzyme. [less ▲]

Comparative ultrastructural study of the effects of serum-free medium and dibutyryl-cyclic AMP on newborn rat astroblasts

in Cell & Tissue Research (1976), 167(2), 221-7

Repeated Observations of the Ca II (H and K) Lines in the Spectrum of the A0ep Star with IR Excess HD 190073; Interpretation via a Resonance Scattering Mechanism

in Bulletin of the American Astronomical Society (1976, March)

EDDIE BURNS Portrait

Article for general public (1976)

Rocket and ground-based measurements of the dayside magnetospheric cleft from Cape Parry, N.W.T.

in Geophysical Research Letters (1976), 3

On Dec. 6, 1974, a Black Brant VD rocket was launched from Cape Parry, N.W.T., into the dayside magnetospheric cleft. The prime launch criterion was the detection of 6300-A emission by two ground-based ... [more ▼]

On Dec. 6, 1974, a Black Brant VD rocket was launched from Cape Parry, N.W.T., into the dayside magnetospheric cleft. The prime launch criterion was the detection of 6300-A emission by two ground-based scanning photometers, but support was provided by two ionosondes. The payload passed through a narrow region of soft electron precipitation, a broader region of enhanced electron densities, and a similarly broad region of O I 5577-A and 6300-A emission. At apogee (236 km), the payload had not penetrated into the 5200-A emission, which had a very sharp equatorward boundary and extended far into the polar cap, presumably as a result of antisunward convection. [less ▲]

Effects of dibutyryl cyclic AMP on cultured brain cells from chick embryos of different ages.

in Experientia (1976), 32(1), 40-42