Evolution of plasmon excitations across the phase diagram of the cuprate superconductor La2−x_{2-x}Srx_{x}CuO4_4

We use resonant inelastic x-ray scattering (RIXS) at the O $K$- and Cu $K$-edges to investigate the doping- and temperature dependence of low-energy plasmon excitations in La$_{2-x}$Sr$_{x}$CuO$_4$. We observe a monotonic increase of the energy scale of the plasmons with increasing doping $x$ in the underdoped regime, whereas a saturation occurs above optimal doping $x \gtrsim 0.16$ and persists at least up to $x = 0.4$. Furthermore, we find that the plasmon excitations show only a marginal temperature dependence, and possible effects due to the superconducting transition and the onset of strange metal behavior are either absent or below the detection limit of our experiment. Taking into account the strongly correlated character of the cuprates, we show that layered $t$-$J$-$V$ model calculations accurately capture the increase of the plasmon energy in the underdoped regime. However, the computed plasmon energy continues to increase even for doping levels above $x \gtrsim 0.16$, which is distinct from the experimentally observed saturation, and reaches a broad maximum around $x = 0.55$. We discuss whether possible lattice disorder in overdoped samples, a renormalization of the electronic correlation strength at high dopings, or an increasing relevance of non-planar Cu and O orbitals could be responsible for the discrepancy between experiment and theory for doping levels above $x = 0.16$.Comment: 19 pages, 11 figure

A synopsis of the ecology of Protura (Arthropoda: Hexapoda)

This publication reviews the literature on the ecology of Protura. Current knowledge is scarce, fragmentary and scattered among papers which do not all strictly deal with ecology or soil arthropods communities. Therefore all available information is summarized in order to better understand the ecology of these arthropods. The density of Protura ranges from hundreds to thousands of individuals per m\ub2. Their aggregate distribution is probably related to food (fungal hyphae) availability and quality, and to the production of aggregation pheromones. Protura tend to form species assemblages characterizing different habitats. Their populations often show an unbalanced sex ratio in favour of females, suggesting that a single male can fertilize several females, perhaps via spermatophores. For some species only females have been collected, which suggests the possibility of parthenogenesis. Our analysis of the available information on phenology and population dynamics of Protura points toward annual cycles with one, two or more peaks of reproductive activity

Researches at the Monte Abatone necropolis (Cerveteri)

The Authors illustrate the ‘Monte Abatone Project’, focusing on the important necropolis South of the ancient city of Caere. The area in its archaeological and topographical features was not further studied since the geophysical campaigns (1957-1961) by the Lerici Foundation. The main focus is the large area around the Campana Tumulus, previously left unexplored in the large plan by the Lerici Foundation. Excavations in 2018-2021 on the South side of this area led, conversely, to discover a possible ‘family’ cluster of tombs, dating to at least between the early Orientalizing and the early/middle Archaic period: these tombs were of fossa, semi-constructed, single-chamber and C2 types. Also, further unknown sectors of the necropolis were found not far from this cluster, with a concentration of tombs of the early semi-constructed type (first half of VII cent. BCE), provided with small tumuli, ordered in two approximatively parallel rows and all oriented North-West. This suggests the existence of a planning by some form of ‘urban’ authority, at a time – beginning with the Early Orientalizing period − that marked a considerable acceleration in the economic growth of the city and its civil-political structure. The area West and North of the Campana Tumulus was also investigated, including surveying the edges of the plateau that led to the identification of tombs (VI-III cent. BCE) excavated in the past and partially backfilled, and terraces for funerary rites which are oriented, like the Tumulus, toward the city plateau. Extensive use of laser scanning and photogrammetry allowed to produce a model of the Monte Abatone plateau, a 3D model of both the Campana Tumulus, never surveyed since the first half of the nineteenth century and other escaveted tombs