Search results for "QE"
showing 10 items of 457 documents
An overview of the geochemical characteristics of oceanic carbonatites: New insights from Fuerteventura carbonatites (Canary islands)
2021
The occurrence of carbonatites in oceanic settings is very rare if compared with their continental counterpart, having been reported only in Cape Verde and Canary Islands. This paper provides an overview of the main geochemical characteristics of oceanic carbonatites, around which many debates still exist regarding their petrogenesis. We present new data on trace elements in minerals and whole-rock, together with the first noble gases isotopic study (He, Ne, Ar) in apatite, calcite, and clinopyroxene from Fuerteventura carbonatites (Canary Islands). Trace elements show a similar trend as Cape Verde carbonatites, almost tracing the same patterns on multi-element and REE abundance diagrams. 3…
Architectural effects on fossil preservation. The case of macaroni coralline algae
2020
Coralline red algae with protuberances in their thalli are common and instructive examples of fabricational effects on fossil preservation. The body (thallus) of non-geniculate coralline algae is a coherent mass of cell filaments. All vegetative cells, except the epithallial ones at the tip of each filament are enclosed by a high-Mg calcite wall. Many extant and extinct species of coralline algae have protuberances in their thalli. Protuberances appear both on the dorsal surface of algae that grow attached to a rigid substrate and in unattached specimens living on loose sediment. In either case, protuberances develop due to a higher growth rate of fi laments in their centre. In each growth …
Witnesses of the early Pliocene sea-level rise in the Manilva Basin (Málaga, S Spain)
2020
The Sierra de la Utrera, a relief in the Manilva Basin (Malaga, SW Spain), shows bored surfaces at different heights above present-day sea level, from 96 m to 287 m. Borings occur in the eastern, central, and western parts of the Canuto de la Utrera, a prominent gorge in the central southern part of the relief excavated in Mesozoic limestones, as well as on the western end of the Canuto Chico, a smaller canyon in the northern part. Pliocene marine deposits fossilized the bored surfaces. Bored boulders of the substrate are embedded in the Pliocene sediments. The traces Gastrochaenolites ispp., Entobia ispp., Caulostrepsis ispp., Circolites kotoucensis, and Ericichnus asgaardi have been ident…
Late Carnian-Early Norian ammonoids from the GSSP candidate section Pizzo Mondello (Sicani mountain, Sicily).
2012
A small collection of ammonoids from the Upper Triassic Scillato Formation at Pizzo Mondello (Agrigento, Sicily) is studied. The specimens were collected in a framework of a project aimed at providing an integrated high-resolution bio-chronostratigraphic support to the Upper Carnian-Norian magnetostratigraphic scale defined at this site, that is located in an historical area from which G.G. Gemmellaro collected the Upper Triassic of ammonoids monographed at the beginning of the XX century. The specimens from Pizzo Mondello were bed-by-bed sampled and represent the first collection of Upper Triassic ammonoids described from Sicily since Gemmellaro time. Quite several levels of the Pizzo Mond…
Output Field-Quadrature Measurements and Squeezing in Ultrastrong Cavity-QED
2015
We study the squeezing of output quadratures of an electro-magnetic field escaping from a resonator coupled to a general quantum system with arbitrary interaction strengths. The generalized theoretical analysis of output squeezing proposed here is valid for all the interaction regimes of cavity-quantum electrodynamics: from the weak to the strong, ultrastrong, and deep coupling regimes. For coupling rates comparable or larger then the cavity resonance frequency, the standard input–output theory for optical cavities fails to calculate the variance of output field-quadratures and predicts a non-negligible amount of output squeezing, even if the system is in its ground state. Here we show that…
Algunos aspectos de la variabilidad de los oogonios en poblaciones actuales del género <i>Chara</i> (Charophyceae). Aplicación paleontoló…
1986
A critical revision of some useful taxonomic criteria in paleontology of Charophytes is carried Out. The results are based in four modern populations ((<i>Chara aculeolata, Chara</i> aff.<i>baltica, Chara delicatula</i> and <i>Chara globularis</i>) and they permit to make some serious objections to these critera. The results are related with three principal aspects: the meaning of the absolute magnitudes of me girogonite, the behaviour of his joint variation and the morphological variability during the calcification process. In general, and for each one of the four populations, an absence of influence of the position of the girogonite over their measureme…
Microstructure of Triassic conodont Pseudofurnishius murcianus van den Boogaard: Functional implications
2020
Pseudofurnishius murcianus van den Boogaard is a Triassic conodont with a very characteristic morphology, a blade with a rostral platform heavily denticulated, that makes it easily distinguishable from other coeval species. It is a well-know taxon that has been the object of several palaeobiological works, focused on their apparatus reconstruction, ontogeny and, recently, their P 1 element function. In order to increase our palaeobiology knowledge of this taxon we undertook a histological analysis to corroborate the functional hypothesis established for this conodont. The histological study demonstrated the presence of different microstructural types, suggesting that they are functional ada…
SISALv2: a comprehensive speleothem isotope database with multiple age–depth models
2020
Characterizing the temporal uncertainty in palaeoclimate records is crucial for analysing past climate change, correlating climate events between records, assessing climate periodicities, identifying potential triggers and evaluating climate model simulations. The first global compilation of speleothem isotope records by the SISAL (Speleothem Isotope Synthesis and Analysis) working group showed that age model uncertainties are not systematically reported in the published literature, and these are only available for a limited number of records (ca. 15 %, n = 107/691). To improve the usefulness of the SISAL database, we have (i) improved the database’s spatio-temporal coverage and (ii) create…
Detection, tracking and event localization of jet stream features in 4-D atmospheric data
2012
We introduce a novel algorithm for the efficient detection and tracking of features in spatiotemporal atmospheric data, as well as for the precise localization of the occurring genesis, lysis, merging and splitting events. The algorithm works on data given on a four-dimensional structured grid. Feature selection and clustering are based on adjustable local and global criteria, feature tracking is predominantly based on spatial overlaps of the feature's full volumes. The resulting 3-D features and the identified correspondences between features of consecutive time steps are represented as the nodes and edges of a directed acyclic graph, the event graph. Merging and splitting events appear in…
Entanglement control in hybrid optomechanical systems
2012
We demonstrate the control of entanglement in a hybrid optomechanical system comprising an optical cavity with a mechanical end-mirror and an intracavity Bose-Einstein condensate (BEC). Pulsed laser light (tuned within realistic experimental conditions) is shown to induce an almost sixfold increase of the atom-mirror entanglement and to be responsible for interesting dynamics between such mesoscopic systems. In order to assess the advantages offered by the proposed control technique, we compare the time-dependent dynamics of the system under constant pumping with the evolution due to the modulated laser light.