Superallowed Gamow-Teller decay of the doubly magic nucleus 100Sn

The shell structure of atomic nuclei is associated with 'magic numbers' and originates in the nearly independent motion of neutrons and protons in a mean potential generated by all nucleons. During β(+)-decay, a proton transforms into a neutron in a previously not fully occupied orbital, emitting a positron-neutrino pair with either parallel or antiparallel spins, in a Gamow-Teller or Fermi transition, respectively. The transition probability, or strength, of a Gamow-Teller transition depends sensitively on the underlying shell structure and is usually distributed among many states in the neighbouring nucleus. Here we report measurements of the half-life and decay energy for the decay of (100)Sn, the heaviest doubly magic nucleus with equal numbers of protons and neutrons. In the β-decay of (100)Sn, a large fraction of the strength is observable because of the large decay energy. We determine the largest Gamow-Teller strength so far measured in allowed nuclear β-decay, establishing the 'superallowed' nature of this Gamow-Teller transition. The large strength and the low-energy states in the daughter nucleus, (100)In, are well reproduced by modern, large-scale shell model calculations.     

Pentobarbital-induced increase of rat liver phosphoprotein phosphatase

Résumé Le pentobarbital provoque un accroissement important de l'activité de la phosphoprotein-phosphatase extramicrosomiale du foie du rat. L'accroissement de l'activité de l'enzyme se produit dejà 20 min après l'administration du médicament (+40%) et dure autant que le traitement (+50–70%). Le niveau de l'induction dépend de la dose du pentobarbital. L'induction est bloquée par l'administration simultanée du cycloheximide ou du SKF 525-A.     

Immunological recovery of thymectomized and sham-thymectomized lethally irradiated mice reconstituted with syngeneic hone marrow cells

Summary Immunological functions of lethally irradiated mice reconstituted with syngeneic bone marrow cells recover after 5–6 weeks. In mice that had been thymectomized before irradiation and reconstitution, T-cell function is deficient but the B-cell function is preserved.Supported by subcontract No. 3322 from the Biology Division of Oak Ridge National Laboratory of the University of Tennessee, and by the Fulbright-Hays Program. Present address: Department of Physiology, University of Zagreb, Faculty ofOperated by the Union Carbide Corporation for the Department of Energy.     

Effects of progesterone and estradiol benzoate on superoxide dismutase activity in the brain of male rats

The activities of mitochondrial, manganese-containing superoxide dismutase (MnSOD) and cytoplasmic, copper-zinc-containing superoxide dismutase (CuZnSOD) were measured in subcellular fractions of whole brain homogenates prepared from intact and gonadectomized (GDX) male rats, untreated or treated subcutaneously (sc) with a single dose of 2 mg progesterone (P) and/or 5 g estradiol benzoate (EB). Neither MnSOD nor CuZnSOD was affected by the removal of the testes. Similarly, CuZnSOD activity was steady following systemic administration of P and/or EB to intact and GDX animals 2 h or 24 h prior to sacrifice. On the other hand, both P and EB suppressed MnSOD in the brain of either intact or GDX rats. These results suggest involvement of P and EB in the control of MnSOD activity in the brain of male rats.     

New bone induction by demineralized bone matrix in immunosuppressed rats

Subcutaneous implantation of demineralized bone matrix (DBM) initiates a sequence of developmental events which culminate in endochondral bone formation. To test the effects of T-cell deficiency on new bone formation, the morphology of DBM-induced bone was examined in rats thymectomized at three weeks of age and in thymectomized or nonthymectomized rats lethally irradiated and reconstituted with syngeneic bone marrow. At 24 days after implantation, bone induction in control rats was appropriate for their age, while thymectomized-irradiated-reconstituted rats and thymectomized rats had significantly more new bone and larger bone marrow space than the controls. In non-thymectomized, irradiated and reconstituted rats, bone induction occurred in only 25% of the animals, compared to 95% in other groups.     

Effect of trypsin,S-adenosylmethionine and ethionine on L-serine sulfhydrase activity

Summary Trypsin causes an activation of serine sulfhydrase in the liver extracts from intact animals, but inhibits enzyme activity in the liver of ethionine treated rats. Trypsin also decreases an elevation of serine sulfhydrase activity caused by S-adenosylmethionine.This work was supported by the Serbian Medical Research Foundation.     

Some Epistemic Questions of Cosmology

We discuss a number of fundamental aspects of modern cosmological concepts, from the phenomenological, observational, theoretical and epistemic points of view. We argue that the modern cosmology, despite a great advent, in particular in the observational sector, is yet to solve important problems, posed already by the classical times. In particular the stress is put on discerning the scientific features of modern cosmological paradigms from the more speculative ones, with the latter immersed in some aspects deeply into mythological world picture. We finally discuss the principal paradigms, which are present in the modern cosmological studies and evaluate their epistemic merits.     

Über photogalvanische Erscheinungen bei organischen Redoxsystemen

Summary An attempt has been made to systematize the phenomena which are included by the term of Becquerel's effect.Becquerel's photogalvanic effect has been thoroughly investigated on systems composed of organic redox-dyes and organic acceptors, especially regarding the speed of changes in potential and the influence of reducing and oxidizing agents. Possibilities of increasing and stabilizing the electromotor forces of the investigated photogalvanic cells have been ascertained. It has been proved that the well known rules governing inhibition of chemical reaction apply to the investigated systems.     

Effect of electroshock upon nucleic acid concentrations in various parts of cat brain

Zusammenfassung Beim Elektroschock kommt es zu bedeutenden Erniedrigungen der Konzentration von RNA in verschiedenen kortikalen und subkortikalen Teilen des zentralen Nervensystems der Katze, während sich die Konzentration von DNA in normalen Grenzen hält.