1,720,982 research outputs found
Insights on the paleoecology of Ammonia (Foraminifera, Rotalioidea) from Miocene carbonates of central and southern Apennines (Italy)
No full textThe Miocene transgression in central and southern Apennines is commonly represented by a sharp contact between shallow-water open-marine bioclastic limestones and the underlying Cretaceous or Eocene bedrock. Only in a few areas, very proximal marine or paralic deposits, witnessing the first stage of the transgression, have been preserved. These deposits contain rich foraminiferal assemblages commonly dominated by specimens of the genus Ammonia. The paleontological and paleoenvironmental analysis revealed that the Miocene Ammonia shared the same habitat and ecological requirements of living representatives from recent shoreline environments. Small Ammonia forma ‘tepida’ have been found in Miocene marginal paralic organic-rich bottoms with restricted water circulation and possibly under natural metal pollution. Big Ammonia forma ‘beccarii’ characterize Miocene nearshore marine bottoms with vegetated areas under fresh water inputs. The endoskeletal lamellar folding called tooth-plate, which characterizes recent representatives, is observed in fossil specimens of both tepida and beccarii morphogroups, testifying that there were no major changes in the shell architecture of Ammonia since the early Miocene
Paleoecological and paleoenvironmental insights from Ornatorotaliidae (larger foraminifera)
No full textThe present study deals with the ecology and phylogenetic relationships among species of the genera Ornatorotalia, Granorotalia, and Risananeiza belonging to the Family Ornatorotaliidae. The microfacies analyses allowed us to assign each taxon to its life paleoenvironment within the shallow-water carbonate setting, and to make a comparison with extant species belonging to the family Calcarinidae. While different species of Ornatorotalia and Granorotalia thrived only in the inner ramp, Risananeiza spp. possibly inhabited also deeper environments up to the middle ramp. The phylogenetic relationships among genera and species are here briefly discussed, nonetheless it's still impossible to identify any unambiguous ancestor of this group
Effects of thermal treatment on hardness of AA6082-T6
No full textThis study expounds the effect of thermal treatment on mechanical properties of AA6082-T6 alloy. This aluminum alloy is frequently exploited in welding structures, which causes a mechanical properties deterioration in the Heat Affected Zone (HAZ). Consequently, a thermal treatment is needed to restore most of the lost characteristics but, at the same time, the Unaffected Base Metal (UBM) undergoes a loss. The aim of this work is to provide a model able to predict the response of Brinell Hardness in the UBM zone after postweld thermal treatments. The central composite rotatable design (CCRD) was used to design an experimental plan developing mathematical models as a function of annealing time, and temperature. Statistical approaches have shown a validity of these mathematical models by confirming a good adequacy. These models have been used to construct response surface graphs to describe the effects of the process variables on the mechanical properties of UBM. Finally, an optimization has been performed to show the capability of the used approach
Fault-controlled volcanic vents between the Volsci Range and the magma-rich Tyrrhenian passive margin (Italy)
No full textStratigraphic and taxonomic considerations on the late Cretaceous rudist fauna of Aksai Chin (Western Tibet, China) from the De Filippi collection
Full text linkThe rudist fauna collected in western Tibet in the Aksai Chin area by the DE FILIPPI expedition in 1914 has been reprised and redescribed. This fauna is composed of Radiolites cf. lusitanicus, Radiolites sp., Gorjanovicia cf. endrissi, ? Sauvagesia sp., Sphaerulites sp., Durania sp., and Gyropleu-ra sp. The rudist-bearing beds belong to the Tielongtan Group of the Tianshuihai terrane. The Turo-nian-? Coniacian Xiloqzung Formation (Fm.) bear the older rudists (Radiolites cf. lusitanicus, Radiolites sp., Sphaerulites sp., Durania sp.), whereas younger ages have been determined through microfossil analysis which, compared with the western Neotethys records, suggests an early-mid Campanian age. This allowed to ascribe the younger rudists of the collection (Gorjanovicia cf. endrissi, ? Sauvagesia sp., Gyropleura sp., Radiolites sp.) to the Dongloqzung Formation. Our data confirm that rudist-bea-ring facies in the Tielongtan Group extend at least up to the middle Campanian. The Aksai Chin rudist assemblage should belong to the Southwestern Asian assemblage of the Eastern Mediterranean Sub-province
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
- …
