Invariant Manifolds, the Spatial Three-Body Problem and Space Mission Design

The invariant manifold structures of the collinear libration points for the spatial restricted three-body problem provide the framework for understanding complex dynamical phenomena from a geometric point of view. In particular, the stable and unstable invariant manifold \tubes" associated to libration point orbits are the phase space structures that provide a conduit for orbits between primary bodies for separate three-body systems. These invariant manifold tubes can be used to construct new spacecraft trajectories, such as a \Petit Grand Tour" of the moons of Jupiter. Previous work focused on the planar circular restricted three-body problem. The current work extends the results to the spatial case

Invariant Manifolds, the Spatial Three-Body Problem and Petit Grand Tour of Jovian Moons

The invariant manifold structures of the collinear libration points particular, the stable and unstable invariant manifold "tubes" associated to for the spatial restricted three-body problem provide the framework for understanding complex dynamical phenomena from a geometric point of view. In libration point periodic orbits are phase space structures that provide a conduit for orbits between the primary bodies in separate three-body systems. These invariant manifold tubes can be used to construct new spacecraft trajectories, such as a "Petit Grand Tour" of the moons of Jupiter. Previous work focused on the planar circular restricted three-body problem. The current work extends the results to the spatial case

Dry Hydrogen Production in a Tandem Critical Raw Material-Free Water Photoelectrolysis Cell Using a Hydrophobic Gas-Diffusion Backing Layer

A photoelectrochemical tandem cell (PEC) based on a cathodic hydrophobic gas-diffusion backing layer was developed to produce dry hydrogen from solar driven water splitting. The cell consisted of low cost and non-critical raw materials (CRMs). A relatively high-energy gap (2.1 eV) hematite-based photoanode and a low energy gap (1.2 eV) cupric oxide photocathode were deposited on a fluorine-doped tin oxide glass (FTO) and a hydrophobic carbonaceous substrate, respectively. The cell was illuminated from the anode. The electrolyte separator consisted of a transparent hydrophilic anionic solid polymer membrane allowing higher wavelengths not absorbed by the photoanode to be transmitted to the photocathode. To enhance the oxygen evolution rate, a NiFeOX surface promoter was deposited on the anodic semiconductor surface. To investigate the role of the cathodic backing layer, waterproofing and electrical conductivity properties were studied. Two different porous carbonaceous gas diffusion layers were tested (Spectracarb® and Sigracet®). These were also subjected to additional hydrophobisation procedures. The Sigracet 35BC® showed appropriate ex-situ properties for various wettability grades and it was selected as a cathodic substrate for the PEC. The enthalpic and throughput efficiency characteristics were determined, and the results compared to a conventional FTO glass-based cathode substrate. A throughput efficiency of 2% was achieved for the cell based on the hydrophobic backing layer, under a voltage bias of about 0.6 V, compared to 1% for the conventional cell. For the best configuration, an endurance test was carried out under operative conditions. The cells were electrochemically characterised by linear polarisation tests and impedance spectroscopy measurements. X-Ray Diffraction (XRD) patterns and Scanning Electron Microscopy (SEM) micrographs were analysed to assess the structure and morphology of the investigated materials.Authors gratefully acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 760930 (FotoH2 project)

Toward a Topography of Cross-Cultural Theatre Praxis

In this essay we attempt to map out a conceptual framework for analyzing a cluster of related practices subsumed under the broad banner of "cross-cultural theatre". For the purposes of our discussion, cross-cultural theatre encompasses public performance practices characterized by the conjunction of specific cultural resources at the level of narrative content, performance aesthetics, production processes, and/or reception by an interpretive community. The cultural resources at issue may be material or symbolic, taking the form of particular objects or properties, languages, myths, rituals, embodied techniques, training methods, and visual practices - or what James Brandon calls "cultural fragments" (1990:92). Cross-cultural theatre inevitably entails a process of encounter and negotiation between different cultural sensibilities, although the degree to which this is discernible in any performance event will vary considerably depending on the artistic capital brought to a project as well as the location and working processes involved in its development and execution

Enhanced Photoelectrochemical Water Splitting at Hematite Photoanodes by Effect of a NiFe-Oxide co-Catalyst

Tandem photoelectrochemical cells (PECs), made up of a solid electrolyte membrane between two low-cost photoelectrodes, were investigated to produce “green” hydrogen by exploiting renewable solar energy. The assembly of the PEC consisted of an anionic solid polymer electrolyte membrane (gas separator) clamped between an n-type Fe2O3 photoanode and a p-type CuO photocathode. The semiconductors were deposited on fluorine-doped tin oxide (FTO) transparent substrates and the cell was investigated with the hematite surface directly exposed to a solar simulator. Ionomer dispersions obtained from the dissolution of commercial polymers in the appropriate solvents were employed as an ionic interface with the photoelectrodes. Thus, the overall photoelectrochemical water splitting occurred in two membrane-separated compartments, i.e., the oxygen evolution reaction (OER) at the anode and the hydrogen evolution reaction (HER) at the cathode. A cost-effective NiFeOx co-catalyst was deposited on the hematite photoanode surface and investigated as a surface catalytic enhancer in order to improve the OER kinetics, this reaction being the rate-determining step of the entire process. The co-catalyst was compared with other well-known OER electrocatalysts such as La0.6Sr0.4Fe0.8CoO3 (LSFCO) perovskite and IrRuOx. The Ni-Fe oxide was the most promising co-catalyst for the oxygen evolution in the anionic environment in terms of an enhanced PEC photocurrent and efficiency. The materials were physico-chemically characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM).Authors gratefully acknowledge funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 760930 (FotoH2 project)

Morphobathymetry and formation processes of sediment waves in the Gulf of Valencia continental slope (NW Mediterranean)

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Maturity matrix assessment : evaluation of energy efficiency strategies in Brussels historic residential stock

Energy retrofitting of historic or existing buildings is a challenge that it has not yet been properly solved. Multiple projects and methodologies are published every day but neither of them with the holistic approach that will assure success since the design phase. Nevertheless, these buildings play a key role in the achievement of the ambitious energy saving and greenhouse gas reduction targets that Europe has fixed for 2020 and 2050. Research has demonstrated that the impact in terms of decrease of energy use and CO2 will be strong, considering that, in Europe, 80% of the 2030 building stock already exists and 30% are historical buildings. To achieve these goals, reliable data about energy consumption, building components and systems performance of the existing building stock is needed. With the residential stock occupying a 75% of Europe’s floor space, this becomes a difficult task as this stock is never considered as a whole. Its components are installed, serviced and maintained by different companies and in different stages without a holistic approach to the overall building operation. The result is a lack of energy efficiency and feedback of the solutions implemented once the buildings are refurbished. This paper presents a pre-assessment methodology to tackle the energy retrofitting of historic and existing residential buildings based in the Maturity Matrix Assessment. The maturity of the implementation of energy efficiency measures in Brussels historic residential stock is evaluated to measure the gap between the “as is” and “to be” and define future appropriate strategies. The matrix synthetizes appropriate strategies for this specific stock that provides a global map of the problematic, requirements and solutions

The detection of anti-Trichinella antibodies in free-ranging Nebrodi Regional Park black pigs from Sicily, Italy, suggests the circulation of Trichinella britovi in the island

Abstract • Zoonotic nematodes of the genus Trichinella are known to occur in countries bordering the Mediterranean Sea. For example, Trichinella spiralis was reported in pigs and humans at the turn of the Second World War in Sicily and Trichinella britovi in pigs, red foxes and dogs from Corsica and Sardinia since 2004. Following the discovery of T. britovi in Corsica and Sardinia, a question arose as to whether this species was also present in Sicily which is located only 3.14 km from continental Italy. To address this query, we investigated the presence of anti-Trichinella antibodies in the serum of Nebrodi black pigs, a breed that is bred in the wild in the Nebrodi Regional Park, a protected area of the island rich in flora and fauna. Blood samples were collected from 112 Nebrodi black pigs from five farms. Sera were tested by ELISA and ELISA positive sera were confirmed by Western blot (Wb) using excretory/secretory antigens. Eighteen (16.1%) serum samples belonging to 17 fattening pigs and 1 boar tested positive by Wb. Positive sera tested by Wb using crude worm extract antigens (CWE), displayed a banding pattern similar to the CWE-Wb pattern of T. spiralis and T. britovi reference pig sera but different to that of T. pseudospiralis reference pig sera. No larvae were detected in muscles of serologically positive pigs by artificial digestion. The presence of anti-Trichinella antibodies in the absence of larvae in the muscles, suggests that the pigs were infected with T. britovi and not T. spiralis whose larvae survive in the muscles for at least two years. These results suggest that T. britovi is circulating in Nebrodi Regional Park in Sicily. ELISA testing may constitute a suitable tool for large-scale screening of Trichinella spp. infection in free-ranging pigs, when ELISA-positive sera are confirmed by Wb. Free-ranging animals can act as sentinels for the presence of zoonotic nematodes of the genus Trichinella in wildlife

The fraction of early-type galaxies in low redshift groups and clusters of galaxies

We examine the fraction of early-type (and spiral) galaxies found in groups and clusters of galaxies as a function of dark matter halo mass. We use morphological classifications from the Galaxy Zoo project matched to halo masses from both the C4 cluster catalogue and the Yang et al (2007) group catalogue. We find that the fraction of early-type (or spiral) galaxies remains constant (changing by less than 10%) over three orders of magnitude in halo mass (13<log MH/Msol/h<15.8). This result is insensitive to our choice of halo mass measure, from velocity dispersions or summed optical luminosity. Furthermore, we consider the morphology-halo mass relations in bins of galaxy stellar mass M*, and find that while the trend of constant fraction remains unchanged, the early-type fraction amongst the most massive galaxies (11<log M*/Msol/h <12) is a factor of three greater than lower mass galaxies (10<logM*/Msol/h<10.7). We compare our observational results with those of simulations presented in De Lucia et al (2011), as well as previous observational analyses, and semi-analytic bulge (or disc) dominated galaxies from the Millennium Simulation. We find the simulations recover similar trends as observed, but may over-predict the abundances of the most massive bulge dominated (early-type) galaxies. Our results suggest that most morphological transformation is happening on the group scale before groups merge into massive clusters. However, we show that within each halo a morphology-density relation remains: it is summing the total fraction to a self-similar scaled radius which results in a flat morphology-halo mass relationship.Comment: 9 page, 5 figures, modified to match accepted version (MNRAS

A tribute to Marie Tharp: Mapping the seafloor of back-arc basins, mid-ocean ridges, continental margins and plate boundaries

European Geosciences Union (EGU) General Assembly 2020, 4-8 May 2020Marie Tharp (1920-2006) was a pioneer of modern oceanography. She was an American geologist and oceanographic cartographer who, together with his husband Bruce Heezen, generated the first bathymetric map of the Atlantic Ocean floor. Tharp's work revealed the detailed topography and geological landscape of the seafloor. Her work revealed the presence of a continuous rift valley along the Mid-Atlantic Ridge axis, causing a paradigm in earth sciences that led to the acceptance of plate tectonics and continental drift theories. Piecing maps together in the late 1940s and early 1950s, Marie and his partner Bruce Heezen discovered the 75.000 km underwater ridge bounding around the globe. By this finding, they laid the conclusion from geophysical data that the seafloor spreads from mid-ocean ridges and that continents are in motion with respect to one another¿a revolutionary geological theory at that time. Many years later, satellite images demonstrate that Tharp¿s maps were accurate. In this contribution, we focus on detailed bathymetric maps collected from year 1992 to today, which include bathymetric maps from diverse parts of the world. For instance, we will show a) Back-arc basins (i.e. the Bransfield Basin, Antarctica; and the North Fiji Basin, SW Pacific); b) Mid-ocean ridges and fracture zones (i.e. the MAR at the South of Azores, the MAR at the Oceanographer-Hayes, and the St. Paul Fracture Zone at the Equator), and c) Active tectonic structures from the Gulf of Cadiz and Alboran Sea, located at the Africa-Eurasia plate boundary (Gibraltar Arc). Regarding this last area, we will characterize the seafloor expression of the fault systems, as well as the subsurface structure of the faults in the Gulf of Cadiz and Alboran Sea. This zone is characterized by a moderate seismicity, mainly reverse and strike-slip focal mechanisms; although large historical (AD1755, AD1829) and instrumental earthquakes or large/great magnitude also occurred, such as the earthquakes of 1969, 1994, 2004 and 2016. In addition, the Gulf of Cadiz-Alboran Sea area is compartmentalized in different crustal domains, bounded by active strike-slip fault systems. We adopted a multi-scale approach, including morphological analysis of shipboard multibeam bathymetry, near-bottom bathymetry obtained with Autonomous Underwater Vehicles (AUVs) at a resolution of 1-2 m, and medium to deep penetration multi-channel seismic (MCS) data. Finally, we will also show a couple of videos from recent marine cruises in the Gibraltar Arc (SHAKE-2015 and INSIGHT-2018), both using state-of-the-art high-resolution marine technologie