31 research outputs found
Overview of ESAâs Earth Observation upcoming small satellites missions
The âNew Spaceâ paradigm, has enabled the creation of many new opportunities in the space sector like the development of a large number of missions based on small and nano-satellites. The European Space Agency (ESA) is supporting these new development approaches and technology advancements, including use of Commercial-Off-The-Shelf (COTS) components to enable missions based on small and nano satellites. ESAâs Earth Observation Programmes Directorate (ESA-EOP) is already involved not only in the implementation of technologies exploiting the capabilities offered by small and nano-satellites as a complement to the EOP scientific and application-driven flagship satellites, but also in the quick validation of new approaches like A.I, super resolution or more in general in orbit data processing. ESA-EOP developments in the area of small and nano satellites are spread in three different programmatic lines, each with its own objectives: Scout and F-sat Missions and the InCubed Programme.
This paper presents the overall ESA-EOP small missions strategy providing a brief insight on the genesis of each programmatic line and their selection processes including an update of the status of the first initiatives and missions under development or study
Beam manipulation for resonant plasma wakefield acceleration
Plasma-based acceleration has already proved the ability to reach ultra-high accelerating gradients. However
the step towards the realization of a plasma-based accelerator still requires some e
ff ort to guarantee high brightness beams, stability and reliability. A significant improvement in the efficiency of PWFA has been
demonstrated so far accelerating a witness bunch in the wake of a higher charge driver bunch. The transformer
ratio, therefore the energy transfer from the driver to the witness beam, can be increased by resonantly exciting
the plasma with a properly pre-shaped drive electron beam. Theoretical and experimental studies of beam
manipulation for resonant PWFA will be presented her
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Inflation and Dark Energy from spectroscopy at z > 2
The expansion of the Universe is understood to have accelerated during two
epochs: in its very first moments during a period of Inflation and much more
recently, at z < 1, when Dark Energy is hypothesized to drive cosmic
acceleration. The undiscovered mechanisms behind these two epochs represent
some of the most important open problems in fundamental physics. The large
cosmological volume at 2 < z < 5, together with the ability to efficiently
target high- galaxies with known techniques, enables large gains in the
study of Inflation and Dark Energy. A future spectroscopic survey can test the
Gaussianity of the initial conditions up to a factor of ~50 better than our
current bounds, crossing the crucial theoretical threshold of
of order unity that separates single field and
multi-field models. Simultaneously, it can measure the fraction of Dark Energy
at the percent level up to , thus serving as an unprecedented test of
the standard model and opening up a tremendous discovery space
Syntectonic fluid flow and deformation mechanisms within the frontal thrust of foreland fold-and-thrust belt: Example from the Internal Jura, Eastern France
International audienceStructural mapping and microstructural analyses are combined with stable, clumped, and radiogenic isotopes to unravel deformation mechanisms and syntectonic fluid flow during upward propagation along the Fuans frontal thrust of the internal part of the Jura fold-and-thrust belt. The Fuans thrust cuts through Upper Jurassic-Lower Cretaceous carbonate deposits, branches into two splays, and generates a system of fault-propagation folds. Folding was accomodated by layer-parallel shortening and layer-parallel shear, which generated flexural slip along bedding surfaces, stylolites, and foliated fabric in marly limestone interbeds. Thrusting was characterized by cycles of mutually overprinting ductile pressure-solution and brittle processes such as frictional sliding and fracturing/veining. This generated foliated tectonites in marls and limestones without significant cataclasis of the host rock. Pressure-solution and micrometer slip along slickenfibers are evidence of aseismic slip, in agreement with the ongoing aseismic anticline growth within the Jura fold-and-thrust, while crackle-like vein texture may account for episodic seismic fracturing. Geochemical data show that Fuans thrust acted as a conduit for the downward infiltration of meteoric-derived fluids, which channelized along foliated tectonites during syntectonic fluid flow. Calcite mineralizations precipitated at temperatures between 54 °C and 10 °C, showing an increased contribution of carbon derived from organic carbon respiration in soils in colder paleofluids. This indicates a progressive opening of the system, characterized by a more efficient and extensive meteoric fluids circulation. Considering the highest recorded temperature of 54 °C and assuming the modern geothermal gradient of 30 °C/km, thrusting in the exposed outcrop initiated at burial depths of at least âŒ1.4 km
Growth of a Pleistocene giant carbonate vein and nearby thermogene travertine deposits at Semproniano, southern Tuscany, Italy. Estimate of CO2 leakage
Received 29 October 2015
Received in revised form 1 April 2016 Accepted 6 April 2016
Available online 13 April 2016
Keywords:
Travertine
Vein
CO2 leakage Hydrothermalism Isotope
Quaternary climate
1. Introduction
Thermogene travertines form through precipitation of CaCO3 from supersaturated fluids usually generated and discharged in volcano- tectonic settings, often deposited in proximity of active geothermal springs or along open fissures (Pentecost, 1995; Ford and Pedley, 1996; Pentecost, 2005; Crossey et al., 2006). In addition of being impor- tant decorative and construction stones since at least the Roman time (Calvo and Regueiro, 2010), a renewed world-wide interest for thermogene travertine deposits resides in their importance to be
â Correspondingauthorat:DipartimentodiScienzeâSezionediGeologia,UniversitĂ degli Studi âRoma Treâ, L.go S.L. Murialdo, 1-00146 Rome, Italy.
E-mail address: [email protected] (G. Berardi).
http://dx.doi.org/10.1016/j.tecto.2016.04.014
0040-1951/© 2016 Elsevier B.V. All rights reserved.
abstract
A giant carbonate vein (â„ 50 m thick; fissure ridge travertines) and nearby travertine plateaus in the Semproniano area (Mt. Amiata geothermal field, southern Tuscany, Italy) are investigated through a multidisciplinary approach, including field and laboratory geochemical analyses (U/Th geochronology, C, Nd, O and Sr isotope systematics, REE abundances, and fluid inclusion microthermometry). The main aim of this work is to under- stand: (1) modes and rates for the growth of the giant vein and nearby travertine deposits within a Quaternary volcano-tectonic domain; (2) implications in terms of the CO2 leakage; and (3) possible relationships with Quaternary paleoclimate and hydrological oscillations. Results show that the giant vein was the inner por- tion of a large fissure ridge travertine and grew asymmetrically and ataxially through repeated shallow fluid injections between N650 and 85 ka, with growth rates in the 10â2â10â3 mm/a order. The giant vein developed mainly during warm humid (interglacial) periods, partially overlapping with the growth of near- by travertine plateaus. Estimated values of CO2 leakage connected with the vein precipitation are between about 5 Ă 106 and 3 Ă 107 mol aâ1 kmâ2, approximately representing one millionth of the present global CO2 leakage from volcanic areas. Temperature estimates obtained from O-isotopes and fluid inclusion microthermometry indicate epithermal conditions (90â50 °C) for the circulating fluid during the giant vein growth, with only slight evidence of cooling with time. Geochemical and isotope data document that the travertine deposits formed mainly during Pleistocene warm humid periods, within a tectonically- controlled convective fluid circuit fed by meteoric infiltration and maintained by the regional geothermal anomaly hosted by the carbonate reservoir of the Mt. Amiata field
Growth of a Pleistocene giant carbonate vein and nearby thermogene travertine deposits at Semproniano, southern Tuscany, Italy: Estimate of CO2 leakage
A giant carbonate vein (â„50m thick; fissure ridge travertines) and nearby travertine plateaus in the Semproniano area (Mt. Amiata geothermal field, southern Tuscany, Italy) are investigated through a multidisciplinary approach, including field and laboratory geochemical analyses (U/Th geochronology, C, Nd, O and Sr isotope systematics, REE abundances, and fluid inclusion microthermometry). The main aim of this work is to understand: (1) modes and rates for the growth of the giant vein and nearby travertine deposits within a Quaternary volcano-tectonic domain; (2) implications in terms of the CO2 leakage; and (3) possible relationships with Quaternary paleoclimate and hydrological oscillations. Results show that the giant vein was the inner portion of a large fissure ridge travertine and grew asymmetrically and ataxially through repeated shallow fluid injections between >650 and 85ka, with growth rates in the 10-2-10-3 mm/a order. The giant vein developed mainly during warm humid (interglacial) periods, partially overlapping with the growth of nearby travertine plateaus. Estimated values of CO2 leakage connected with the vein precipitation are between about 5Ă106 and 3Ă107 mola-1 km-2, approximately representing one millionth of the present global CO2 leakage from volcanic areas. Temperature estimates obtained from O-isotopes and fluid inclusion microthermometry indicate epithermal conditions (90-50°C) for the circulating fluid during the giant vein growth, with only slight evidence of cooling with time. Geochemical and isotope data document that the travertine deposits formed mainly during Pleistocene warm humid periods, within a tectonically-controlled convective fluid circuit fed by meteoric infiltration and maintained by the regional geothermal anomaly hosted by the carbonate reservoir of the Mt. Amiata field
Novel A-ring and B-ring modified combretastatin A-4 (CA-4) analogues endowed with interesting cytotoxic activity.
A novel class of combretastatins, modified at A-ring or both A- and B-rings, mainly by replacement with benzofuran or benzo[b]thiophene, were synthesized. The new heterocombretastatins showed good cytotoxic activity on BMEC and H-460 cell lines. The aminocombretastatin 9f potently inhibits cell growth of BMEC and combretastatin-resistant HT-29 cell lines, with potential interest to treat colon carcinoma. Heterocombretastatins 9a,b inhibit tubulin polymerization similarly to CA-4 by having a binding to colchicine site five times stronger