First record of Acanthurus chirurgus (Perciformes: Acanthuridae) in the Mediterranean Sea, with some distributional notes on Mediterranean Acanthuridae

The occurrence of the doctorfish Acanthurus chirurgus is reported for the first time in the Mediterranean Sea, off Elba Island, Tyrrhenian Sea (42.726667° N, 10.434444° E). This record is tentatively related to aquarium release. The occurrence of Acanthuridae in the Mediterranean Sea is briefly reviewed, and some distributional notes on Acanthurus coeruleus and Acanthurus monroviae in the Mediterranean are provided

Mt. Etna primary melts from 600 ka to the present day characterized by geochemistry of melt inclusions

The geochemical and isotopic variability of tholeiitic/calcalkaline volcanic products in the southern region of Italy suggest the involvement of an HFSE-enriched, OIB-type mantle component. The Sicily province includes recent to active volcanoes in eastern Sicily (Etna, Iblei), Sicily Channel, Ustica and Prometeo, which are host from tholeiitic to Na-alkaline lavas. The origin of Sicily magma's diversity is debated, but the prevailing hypothesis is that it results from melting a heterogeneous mantle influenced by subducting Ionian lithosphere and interaction with an ascending plume. To address the genesis of the Sicilian magmatism as a function of time, we study olivine-hosted melt inclusions (MIs) from Etna. Etna's magmatic evolution consists of six volcanic stages, started 600 ka ago with submarine tholeiitic lavas and continued until present days eruptions of Na-alkaline products. Here we present the geochemistry of MIs from Tholeiitic (542 & 332 ka), Timpe (154 – 126 ka), AAV (102 ka) and Mongibello (1669 AC) stages. Homogenized MIs are hosted by high-Fo olivine for Tholeiitic stage (Fo 90.5-87) and Timpe stage (Fo 90.5–74), and moderate Fo for AAV and Mongibello stages (Fo 81-72). Spinel from the Tholeiitic and Timpe stages show lower Cr# (~0.5) compare to the alkaline ones (~0.8). Studied MIs demonstrate a wide compositional diversity reflecting the variation of parental melt groups for the separate Etna magmatic stages. Tholeiitic melts differ from all other stages (alkaline melts) by low K2O, P2O5, depleted trace elements and high SiO2, with more refractory spinel suggesting a primitive mantle source for this first Etna magmatic stage. Alkaline MIs from 102 ka – 1669 have similar major and trace element compositions to recent alkaline lavas and published MIs. In contrast, the alkaline MIs from the Timpe stage (K2O 1-3 wt.%) differ from alkaline lavas and MIs from all other stages by higher TiO2, Al2O3, CaO, P2O5, SO3 and low SiO2. Our results indicate that the mantle under Etna is very heterogeneous and requires the involvement of at least two different lherzolite mantle sources for magmas of Tholeiitic and Timpe stages, and a contribution of subduction-derived components for magmas for the more recent stages

The mantle source of lamproites from Torre Alfina, Italy: Evidence from melt inclusions in olivine

The complex post-collisional subduction setting of peninsular Italy, in the central-western Mediterranean region, has given rise to an extremely diverse spectrum of potassium-rich volcanic rocks. The most primitive of these products show trace-element and radiogenic isotope signatures that point to melt derivation from upper mantle domains affected by metasomatism associated with sediment recycling. The style and extent of this metasomatism, and the metasomatic agents responsible for this modification, seem to differ significantly throughout the Italian peninsula. The lamproites of the Tuscan magmatic province, central Italy, are a peculiar and rare example of rocks that require extensive source modification that is not yet well-understood. These rocks are ultrapotassic and mafic in composition and have high compatible trace-element contents. Although bulk-rock compositions have been used to interrogate their petrogenesis, bulk lavas do not reflect the full heterogeneity of their mantle source. Here, we study the geochemistry of melt inclusions in forsterite-rich olivine, which in contrast to their host lavas are snapshots of near-primary melts that have bypassed modification on their way to the surface. The olivines (Fo88-93) from the studied lamproites of Torre Alfina host melt inclusions with major- and trace-element compositions that define two distinct groups. The first is marked by lower SiO2 (47–51 vs. 50–60 wt%) and higher K2O (11–17 vs. 8–14 wt%), CaO (3.5–6 vs. 1.5–5 wt%), TiO2 (1.8–2.4 vs. 0.3–1.8 wt%), P2O5 (1.0–1.7 vs. 0.1–0.9 wt%) and different trace-element contents. Group-1 melts are generally similar to other Tuscan lamproites, whereas group-2 melts are, in terms of trace elements, more akin to the Tuscan high-K calc-alkaline mafic rocks. We interpret these two melt types to originate from a sediment-metasomatised mantle source, which is characterised by distinct (vein) lithologies arising from superimposed metasomatic events. The Sr-Nd-Pb isotope compositions of a subset of the studied inclusions, analysed by wet chemistry and TIMS techniques, will be presented to further constrain the mantle source of these unusual and hitherto unreported primitive melt compositions, and ultimately better understand lamproite petrogenesis

Gut Microbiome of an 11th Century A.D. Pre-Columbian Andean Mummy

The process of natural mummification is a rare and unique process from which little is known about the resulting microbial community structure. In the present study, we characterized the microbiome of paleofeces, and ascending, transverse and descending colon of an 11th century A.D. pre-Columbian Andean mummy by 16S rRNA gene high-throughput sequencing and metagenomics. Firmicutes were the most abundant bacterial group, with Clostridium spp. comprising up to 96.2% of the mummified gut, while Turicibacter spp. represented 89.2% of the bacteria identified in the paleofeces. Microbiome profile of the paleofeces was unique when compared to previously characterized coprolites that did not undergo natural mummification. We identified DNA sequences homologous to Clostridium botulinum, Trypanosoma cruzi and human papillomaviruses (HPVs). Unexpectedly, putative antibiotic-resistance genes including beta-lactamases, penicillin-binding proteins, resistance to fosfomycin, chloramphenicol, aminoglycosides, macrolides, sulfa, quinolones, tetracycline and vancomycin, and multi-drug transporters, were also identified. The presence of putative antibiotic-resistance genes suggests that resistance may not necessarily be associated with a selective pressure of antibiotics or contact with European cultures. Identification of pathogens and antibiotic-resistance genes in ancient human specimens will aid in the understanding of the evolution of pathogens as a way to treat and prevent diseases caused by bacteria, microbial eukaryotes and viruses

First principles fluid modelling of magnetic island stabilization by ECCD

International audienceTearing modes are MHD instabilities that reduce the performances of fusion devices. They can however be controlled and suppressed using Electron Cyclotron Current Drive (ECCD) as demonstrated in various tokamaks. In this work, simulations of islands stabilization by ECCD-driven current have been carried out using the toroidal nonlinear 3D full MHD code XTOR-2F, in which a current-source term modeling the ECCD has been implemented. The efficiency parameter is computed and its variations with respect to source width and location are computed. The influence of parameters such as current intensity, source width and position with respect to the island is evaluated and compared to the Modified Rutherford Equation. We retrieve a good agreement between the simulations and the analytical predictions concerning the variations of control efficiency with source width and position. We also show that the 3D nature of the current source term can lead to the onset of an island if the source term is precisely applied on a rational surface. We report the observation of a flip phenomenon in which the O-and X-Points of the island rapidly switch their position in order for the island to take advantage of the current drive to grow

Investigating combined arc and OIB signatures at a post-collisional subduction setting by geochemical and boron isotope analyses of melt inclusions from Vulture, Italy

Recent post-collisional magmatism in central-southern Italy is unique as it is strongly influenced by sediment subduction but also has an intra-plate signature. The composition of the potassium-rich magmatic products covers a wide range of compositions, from subalkaline to strongly alkaline, and from mafic to felsic. The Vulture volcanic centre, located east of the main volcanic front, is considered “anomalous” compared to the other major Quaternary volcanoes, as it shows the eruption of silica-rich and carbonatite lavas, and a magma source with both arc- and OIB-type signatures. To investigate the unique nature of this anomalous magmatism, we analysed 107 Vulture melt inclusions (MIs) trapped in high-forsterite olivine (~87-90 mol% Fo) for major and trace element composition. A subset of 27 MIs was selected for boron isotope and concentration analysis. Based on relative major and trace element enrichment we distinguish two groups of inclusions: Group 1: High CaO (10-16wt.%), TiO2 (1-3 wt.%), Na2O (~ 3wt.%), MgO (4-9 wt.%; n = 80), lower HFSE/HREE and lower LILE/LREE (n = 44); Group 2: Low CaO (6-7 wt.%), TiO2 (0.8-1.5 wt.%), high SiO2 (45-48 wt.%), Al2O3 (18-20 wt.%), K2O (5-7 wt.%; n = 27) and higher LILE/HREE and HFSE/LREE (n = 24). Group 1 MIs have more negative δ11B values (δ11Bav = -20 ‰; n = 23) and lower B concentration ([B]av = 20 ppm; n = 23) compared to Group 2 (δ11Bav = -17 ‰; [B]av = 36 ppm; n = 4). The geochemical distinction between the two groups indicates the involvement of two melt sources with diverse mineralogies. Combining major and trace elements with a more negative δ11B signature of Group 1, suggests a possible additional input of marly sediments to this group. Geophysical data confirm the presence of a slab detachment and mantle inflow under the Vulture volcanic centre, likely responsible for the OIB signature. The geochemistry of the MIs indicates that the OIB signature for this volcano is possibly derived from melts formed due to slab detachment that mix with melts from a sediment metasomatised source

Gravitational theory without the cosmological constant problem, symmetries of space-filling branes and higher dimensions

We showed that the principle of nongravitating vacuum energy, when formulated in the first order formalism, solves the cosmological constant problem. The most appealing formulation of the theory displays a local symmetry associated with the arbitrariness of the measure of integration. This can be motivated by thinking of this theory as a direct coupling of physical degrees of freedom with a "space - filling brane" and in this case such local symmetry is related to space-filling brane gauge invariance. The model is formulated in the first order formalism using the metric and the connection as independent dynamical variables. An additional symmetry (Einstein - Kaufman symmetry) allows to eliminate the torsion which appears due to the introduction of the new measure of integration. The most successful model that implements these ideas is realized in a six or higher dimensional space-time. The compactification of extra dimensions into a sphere gives the possibility of generating scalar masses and potentials, gauge fields and fermionic masses. It turns out that remaining four dimensional space-time must have effective zero cosmological constant.Comment: 26 page

MHD in von Kármán swirling flows, development and first run of the sodium experiment

URL: http://www-spht.cea.fr/articles/s01/004 MHD dans les écoulements de von Kármán | Collaboration VKSNATO Science Series II 26, 35-50 (2001). NATO Advanced Research Workshop, Dynamo and Dynamics, A Mathematical ChallengeWe describe the motivations, development and first run of the Von Kármán Sodium (VKS) experiment built to study high Reynolds number magnetohydrodynamics and applications to the dynamo effect. The flow is optimized using water experiments at scale 1/2 and kinematic dynamo simulations. In VKS run1, induction measurements are made in the presence of an externally applied field. Results are reported concerning the geometry of the induced field and its fluctuations in time

Seroprevalencia del virus de la leucemia bovina en rodeos lecheros del Departamento Iriondo, Santa Fe, Argentina

El objetivo de este trabajo fue determinar la seroprevalencia del virus de la leucemia bovina (VLB) en rodeos lecheros de la Provincia de Santa Fe. Se procesaron 747 muestras mediante la técnica de inmunodifusión en gel de agar. Se realizó un análisis chi-cuadrado para evaluar la asociación entre la categoría y la general, que fue del 79,1%, siendo la prevalencia por categorías de 82,1% para vacas, 56,2% para vaquillonas y 54,5% para toros. En el análisis estadístico se observó una asociación de seropositividad. Los resultados de prevalencia intra-predial fueron entre el 63% y el 96%. La prevalencia estadísticamente significativa entre adultos y seropositividad, fue teniendo éstos 4 veces más chances de ser seropositivos que las vaquillonas. La elevada seroprevalencia del VLB hallada, demuestra que el virus está ampliamente distribuido en los rodeos lecheros de la región sur de la Provincia de Santa Fe