First Evidence of Axial Shape Asymmetry and Configuration Coexistence in

The excited states of N=44 ^{74}Zn were investigated via γ-ray spectroscopy following ^{74}Cu ß decay. By exploiting γ-γ angular correlation analysis, the 2_{2}^{+}, 3_{1}^{+}, 0_{2}^{+}, and 2_{3}^{+} states in ^{74}Zn were firmly established. The γ-ray branching and E2/M1 mixing ratios for transitions deexciting the 2_{2}^{+}, 3_{1}^{+}, and 2_{3}^{+} states were measured, allowing for the extraction of relative B(E2) values. In particular, the 2_{3}^{+}→0_{2}^{+} and 2_{3}^{+}→4_{1}^{+} transitions were observed for the first time. The results show excellent agreement with new microscopic large-scale shell-model calculations, and are discussed in terms of underlying shapes, as well as the role of neutron excitations across the N=40 gap. Enhanced axial shape asymmetry (triaxiality) is suggested to characterize ^{74}Zn in its ground state. Furthermore, an excited K=0 band with a significantly larger softness in its shape is identified. A shore of the N=40 "island of inversion" appears to manifest above Z=26, previously thought as its northern limit in the chart of the nuclides.

First Direct Measurement of an Astrophysical p-Process Reaction Cross Section Using a Radioactive Ion Beam.

We have performed the first direct measurement of the ^{83}Rb(p,γ) radiative capture reaction cross section in inverse kinematics using a radioactive beam of ^{83}Rb at incident energies of 2.4 and 2.7A MeV. The measured cross section at an effective relative kinetic energy of E_{cm}=2.393 MeV, which lies within the relevant energy window for core collapse supernovae, is smaller than the prediction of statistical model calculations. This leads to the abundance of ^{84}Sr produced in the astrophysical p process being higher than previously calculated. Moreover, the discrepancy of the present data with theoretical predictions indicates that further experimental investigation of p-process reactions involving unstable projectiles is clearly warranted.

Absence of Low-Energy Shape Coexistence in

The ^{80}Ge structure was investigated in a high-statistics ß-decay experiment of ^{80}Ga using the GRIFFIN spectrometer at TRIUMF-ISAC through γ, ß-e, e-γ, and γ-γ spectroscopy. No evidence was found for the recently reported 0_{2}^{+} 639-keV level suggested as evidence for low-energy shape coexistence in ^{80}Ge. Large-scale shell model calculations performed in ^{78,80,82}Ge place the 0_{2}^{+} level in ^{80}Ge at 2 MeV. The new experimental evidence combined with shell model predictions indicate that low-energy shape coexistence is not present in ^{80}Ge.

Erratum: Direct Observation of Proton Emission in

This corrects the article DOI: 10.1103/PhysRevLett.123.082501.

Direct Observation of Proton Emission in

The elusive ß^{-}p^{+} decay was observed in ^{11}Be by directly measuring the emitted protons and their energy distribution for the first time with the prototype Active Target Time Projection Chamber in an experiment performed at ISAC-TRIUMF. The measured ß^{-}p^{+} branching ratio is orders of magnitude larger than any previous theoretical model predicted. This can be explained by the presence of a narrow resonance in ^{11}B above the proton separation energy.

Effect of oestradiol dipropionate and testosterone propionate on protein, RNA and DNA contents and RNase and DNase activity in the liver of the toad (Bufo melanosticus).

A single injection of oestradiol dipropionate increased the HSI and protein, RNA and DNA contents and decreased the RNase and DNase activities of the liver of male and female toads. The minimum effective dose of oestrogen required to induce most of these changes was found to be 1 microgram/g (single injection), but the liver RNA content increased at the dose of 0.5 microgram/g. Oestrogen in a dose of 0.1 microgram/g did not cause any of these changes in male and female toads. Testosterone propionate (0.1, 0.5, 1 or 2 micrograms/g, single injection) was mostly ineffective in these respects, while in male toads higher doses of testosterone (1 and 2 micrograms/g) enhanced the liver RNA content only. The oestrogenic responses occurred earlier in female toads than in males. The liver protein and DNA contents increased from the 3rd day in female and on the 5th day in male toads. The liver RNA reached the higher level from the 2nd day in female and from the 3rd day in male. The RNase and DNase activities were reduced from the 2nd and 3rd day, respectively, in female and on the 5th day in male toads.

Action of testosterone in melanin metabolism in liver of toad (Bufo melanostictus).

The melanin content of liver of male toad was altered by testosterone injection. A single injection of testosterone at a dose of 1 microgram/g or 2 microgram/g of body weight caused an increase in melanin content of liver of male toad on the 3rd and 5th day after injection. With lower doses (0.1 microgram/g and 0.5 microgram/g), however, there was no alteration of melanin content of liver. Compared to the results obtained with 1 microgram of testosterone per g of body weight, the degree of response with respect to the melanin content with 2 microgram/g tended to be higher, but the difference was not statistically significant. The female toads remained unaffected with respect to melanin content of liver with these doses of testosterone used.

Effect of estrogen on the melanin content of liver of toad (Bufo melanostictus).

Estrogen injection (1 microgram/g of body weight, single injection) reduced significantly the melanin content of liver of both male and female toads. Estrogen at the dose of 0.1 microgram/g did not cause any change in the amount of melanin in liver of toads. With higher doses of the hormone (2 microgram/g, single injection) the melanin content of liver tended to decrease further but the differences was not statistically significant in comparison with the results of injection of 1 microgram of estrogen per g of body weight. The reduction in the amount of melanin in liver of both male and female toads was noticed within 24 h of injection and was contained up to the 7th day of experiment. It was also found that the maximum fall in the amount of melanin in liver took place within 3 days.

Histochemical studies on the effect of thyroid hormone on alkaline and acid phosphatase activities in liver of fish and amphibia.

The Lata fishes (Ophicephalus punctatus) showed increased alkaline and acid phosphatase activities in liver after immersion for 15-30 days in thyroxine-containing medium (0.025 mug/ml). A single injection of thyroxine (1-2 mug/g of body weight) caused increased acid phosphatase activity in liver of Lata fish in comparison to the controls on the 5th day after experiment but the alkaline phosphatase activity remained unchanged. Both alkaline and acid phosphatases showed increased activities in liver of Lata fishes treated with a single injection of 4 mug of thyroxine per g of body weight on the 5th day. Immersion of Lata fishes in thiourea solution (1 mg/ml) for 15 days did not show any alteration in alkaline or acid phosphatase activities but these enzyme activities decreased after 30 days' immersion in thiourea solution in comparison to the controls. A seasonal variation of alkaline and acid phosphatase activities was observed in liver of Lata fishes. More alkaline phosphatase activity was found in liver of summer fishes than in winter fishes. The winter fishes showed more acid phosphatase activity than the summer fishes. Three consecutive injections of thyroxine (0.1 mug/g of body weight) to toads (Bufo melanostictus) caused increased alkaline and acid phosphatase activities in liver on the 5th day of the experiment, in comparison to the controls.