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The quantum-mechanical nuclear-shell structure determines the stability and limits of the existence of the heaviest nuclides with large proton numbers Z≳ 100 (refs. 1–3). Shell effects also affect the sizes and shapes of atomic nuclei, as shown by laser spectroscopy studies in lighter nuclides4. However, experimental information on the charge radii and the nuclear moments of the heavy actinide elements, which link the heaviest naturally abundant nuclides with artificially produced superheavy elements, is sparse5. Here we present laser spectroscopy measurements along the fermium (Z= 100) isotopic chain and an extension of data in the nobelium isotopic chain (Z= 102) across a key region. Multiple production schemes and different advanced techniques were applied to determine the isotope shifts in atomic transitions, from which changes in the nuclear mean-square charge radii were extracted. A range of nuclear models based on energy density functionals reproduce well the observed smooth evolution of the nuclear size. Both the remarkable consistency of model prediction and the similarity of predictions for different isotopes suggest a transition to a regime in which shell effects have a diminished effect on the size compared with lighter nuclei.

SUMMARY The Impact of "the Underdogs" in Three Processes of Linguistic Change in the Spanish of Morelia, Michoacán This paper deals with the role that the educational and the socioeconomic levels of the speakers play in some processes of linguistic change. Three phenomena of the Spanish grammar in different stages of linguistic change are examined in the light of the data collected among Spanish speakers from Morelia, Michoacan: (a) the opposition "periphrastic/morphological future," (b) the use of pluperfect subjunctive in the apodosis of conditional sentences instead of compound conditional, and (c) the innovative use of the copula estar. Results from the analysis reveal that in the two more advanced change processes (a and b), the lower educational levels and the low socioeconomic group are the leaders, while the group with more formal education and the middle-high socioeconomic group have joined, although with some resistance, the tendency marked by the leader groups. The analysis of the ser/estar opposition evidences an innovative use of the copula estar in the community. This change is in the first stages and consists of an extension of the estar semantic domain. The educational and socioeconomic levels also show differences in the use of this innovative form. Speakers with college education and speakers of the upper-middle socioeconomic group are more resistant to adopt the innovative use. However, speakers with less education and speakers of the low socioeconomic group show a very important proportion of the innovative use. The results found seem to suggest that the size of the group with less education and the size of the low socioeconomic group in communities like the one studied permit the imposition of some changes that are led by them. RESUMO La influo de la "subuloj " en tri procezoj de lingvosangigo en la hispana de Morelia en Michoacdn La artikolo temas pri la rolo de la eduka kaj sociekonomia niveloj de la parolantoj en procezoj de lingvosangigo. La atoro studas tri fenomenojn de la hispana gramatiko en diversaj stadioj de lingvosangigo per faktoj observitaj inter parolantoj de la hispana en Morelia en Michoacán: (1) la alternativo inter helpverba kaj morfologia futuro, (2) la uzo de pluskvamperfekta subjunktivo en la cefpropozicio de kondicaj frazoj anstata la helpverba kondicionalo, kaj (3) la novstila uzo de la kopulo estar. La rezultoj montras, ke en la du pli progresintaj ŝanĝoprocezoj (1 kaj 2), la malpli altaj edukniveloj kaj la malalta sociekonomia grupo gvidas, dum la grupo kun pli da formala edukigo kaj la mezalta sociekonomia grupo postsekvas, ec se kun iom da rezisto, la tendencon indikitan de la gvidantaj grupoj. La analizo de la alternativo ser/estar montras novstilan uzon de estar en la komunumo. Tiu ŝanĝo estas en la komenca stadio kaj konsistas el plivastigo de la signifo de estar. La niveloj kondutas malsame anka rilate al ĉi tiu novaĵo. Parolantoj kun altlerneja edukigo kaj tiuj el la mezalta sociekonomia grupo rezistas la disvastigon de tiu novstila uzo. Aliflanke parolantoj malpli edukitaj kaj sur malpli alta sociekonomia nivelo uzas la novstilaĵon grandkvante. La trovitaj rezultoj sajnas sugesti, ke pro sia grandeco la malaltaj socigrupoj kapablas en socio kiel la studita esti gvidantaj en sango.