How did the carrier shell Xenophora crispa (König, 1825) build its shell? Evidence from the Recent and fossil record

The genus Xenophora comprises species of marine gastropods (Cretaceous-Recent) able to add fragments of various origins to their shell surface. Agglutination potentials vary, from species lacking attachments to species completely covered by agglutinated materials, as in the Mediterranean species Xenophora crispa. Here, we analyse Recent and fossil specimens of Xenophora crispa from the Mediterranean area using SEM and XRD, to better understand their biomineralization patterns and the mechanisms leading to the agglutination of shells, bioclasts and lithoclasts, and their evolution in time. We also provide new data on poorly studied gastropod shell microstructures. We conclude that: (1) most of the Xenophora crispa shell consists of an aragonitic crossed lamellar fabric, but fibrous to spherulitic prismatic fabrics, seemingly of calcite, have been found in the columella and peripheral edge (the thickest parts of the shell); (2) attachment of objects is mediated by a prismatic microstructure, indicating that this may be the most functional fabric in attachment areas in molluscs; and (3) the functional purpose of the agglutination in Xenophora crispa may be related to a snowshoe strategy to successfully colonize muddy substrates, coupled with tactile and olfactory camouflage. Indeed, this species secretes in the columella and peripheral edge a less dense and a more organic rich calcitic fabric, possibly to lighten the shell thickest parts in order not to sink in soft sediments and to facilitate the shell raising from the substrate to create a protected feeding area. This behaviour seems to have been maintained by X. crispa over 2 My time span

A história da certificação ISO 9001 da Embrapa Meio Ambiente.

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Resolving vertical and east-west horizontal motion from differential interferometric synthetic aperture radar : The L'Aquila earthquake

Analysis of surface coseismic displacement has already been obtained for the 6 April 2009 L'Aquila (central Italy) earthquake from differential interferometric synthetic aperture radar (DInSAR) data. Working jointly on ascending and descending DInSAR data makes for a step forward with respect to published preliminary estimates: we process data in order to retrieve a continuous displacement pattern, both in the vertical and horizontal directions, the latter being limited to the eastward component because of the low sensibility of the SAR images used to resolve northward motion. Our analysis provides new insights on the horizontal component of displacement, obtaining a clear picture of eastward displacement patterns over the epicentral area. This result is noteworthy, as until now little information has been available on horizontal displacement following normal-fault events in the central Apennines (Umbria-Marche, 1997, and L'Aquila, 2009), given the lack of dense GPS networks, the only available source of horizontal displacement data in this area. Inverted fault characteristics from such data also show noteworthy differences compared to previous studies, localizing the Paganica fault as the causative fault for the earthquake

IMAGE-BASED RECONSTRUCTION AND ANALYSIS OF DYNAMIC SCENES IN A LANDSLIDE SIMULATION FACILITY

The application of image processing and photogrammetric techniques to dynamic reconstruction of landslide simulations in a scaled-down facility is described. Simulations are also used here for active-learning purpose: students are helped understand how physical processes happen and which kinds of observations may be obtained from a sensor network. In particular, the use of digital images to obtain multi-temporal information is presented. On one side, using a multi-view sensor set up based on four synchronized GoPro 4 Black® cameras, a 4D (3D spatial position and time) reconstruction of the dynamic scene is obtained through the composition of several 3D models obtained from dense image matching. The final textured 4D model allows one to revisit in dynamic and interactive mode a completed experiment at any time. On the other side, a digital image correlation (DIC) technique has been used to track surface point displacements from the image sequence obtained from the camera in front of the simulation facility. While the 4D model may provide a qualitative description and documentation of the experiment running, DIC analysis output quantitative information such as local point displacements and velocities, to be related to physical processes and to other observations. All the hardware and software equipment adopted for the photogrammetric reconstruction has been based on low-cost and open-source solutions

Evolution of frustrated and stabilising contacts in reconstructed ancient proteins

Energetic properties of a protein are a major determinant of its evolutionary fitness. Using a reconstruction algorithm, dating the reconstructed proteins and calculating the interaction network between their amino acids through a coevolutionary approach, we studied how the interactions that stabilise 890 proteins, belonging to five families, evolved for billions of years. In particular, we focused our attention on the network of most strongly attractive contacts and on that of poorly optimised, frustrated contacts. Our results support the idea that the cluster of most attractive interactions extends its size along evolutionary time, but from the data, we cannot conclude that protein stability or that the degree of frustration tends always to decrease

Sentinel-1A/B imagery for terrain deformation monitoring: a strategy for Atmospheric Phase Screening (APS) estimation

This work focus on terrain deformation monitoring by means of C-band Synthetic Aperture Radar (SAR) Sentinel-1A/B imagery exploiting the Persistent Scatterer Interferometry (PSI) technique. The deformation monitoring strategy described in this article is related to a specific monitoring scenario where a relatively small urban area is potentially affected by deformation and its surroundings are stable. In the case study considered in this work, the scenario corresponds to an area of potential subsidence induced by underground water pumping covering an area of interest with a radius of approximately 1 km. The proposed monitoring strategy takes advantage of the specific scenario at hand and, in particular, of the availability of stable areas in the vicinity of the area potentially affected by ground deformation, to estimate the Atmospheric Phase Screen (APS), i.e. signal propagation delay caused by the Earth's atmosphere, in an attempt to minimize the underestimation of the deformation rate