Physical modelling of the interplay between salt-detached gravity gliding and spreading across complex rift topography, Santos Basin, offshore Brazil

The Santos Basin, offshore Brazil contains a complex set of salt-tectonic structures, the origins of which are debated, that is, the Albian Gap and the São Paulo Plateau (SPP). The Albian Gap is a ca. 450 km long, 60 km wide feature characterized by a post-Albian, counter-regional rollover overlying depleted Aptian salt, and in which the Albian is largely absent. The SPP, located immediately downdip, is defined by a pre-salt structural high overlain by ca. 2.5 km thick salt. Another prominent feature is the Merluza Graben, a rift-related depocentre that underlies the southern portion of the Albian Gap and displays significant (3–4 km) base-salt relief along its main faults. Two competing hypotheses have been proposed to explain the kinematics of these provinces. One invokes post-Albian extension in the Albian Gap and kinematically-linked contraction in the SPP. The other invokes post-Albian salt expulsion in the Albian Gap and salt inflation in the SPP. Recent studies, however, suggest these processes likely alternate in time and space, contributing nearly equally to the evolution of these domains. We apply 3D physical modelling to (i) test this hypothesis; and (ii) to more generally understand how gravity gliding and spreading over three-dimensionally variable base-salt relief control regional salt tectonics. The results show a similar salt-related evolution and structural styles to those proposed in the most recent studies. They also (i) explain the origin of the ca. 25 km wide diapir precursor of the Albian Gap by early salt inflation against base-salt steps; (ii) show that normal faults with different polarities and rollover types form due to the interplay between gliding and spreading over different base-salt domains and (iii) provide a mechanism for the origin of strata encased within salt structures. This improves our understanding of the distribution and origin of salt-related structural styles in worldwide salt basins.publishedVersio

STS-99 Shuttle Radar Topography Mission Stability and Control

The Shuttle Radar Topography Mission (SRTM) flew aboard Space Shuttle Endeavor February 2000 and used interferometry to map 80% of the Earth's landmass. SRTM employed a 200-foot deployable mast structure to extend a second antenna away from the main antenna located in the Shuttle payload bay. Mapping requirements demanded precision pointing and orbital trajectories from the Shuttle on-orbit Flight Control System (PCS). Mast structural dynamics interaction with the FCS impacted stability and performance of the autopilot for attitude maneuvers and pointing during mapping operations. A damper system added to ensure that mast tip motion remained with in the limits of the outboard antenna tracking system while mapping also helped to mitigate structural dynamic interaction with the FCS autopilot. Late changes made to the payload damper system, which actually failed on-orbit, required a redesign and verification of the FCS autopilot filtering schemes necessary to ensure rotational control stability. In-flight measurements using three sensors were used to validate models and gauge the accuracy and robustness of the pre-mission notch filter design

Capturing flow transformation processes across an uneven seabed in coarse-grained sediment gravity flow deposits

The upper part of the Jurassic stratigraphy of the Los Molles Formation corresponds to deepwater succession deposited with a regional marine transgression during the early postrift stage of the Neuquén Basin. The present study conducted in the location of Chacay Melehue (Argentina) is used to document the interactions between coarse-grained sediment gravity flows and the depositional relief of a seismic-scale mass transport complex (MTC), with metre-scale mounds and decametric protruding clasts, as an analogue for similar configurations in subsurface systems. The 60 m thick succession is exposed along a 6.5 km long oblique downdip longitudinal profile. Exposure quality permits walking out of individual beds. A total of 16 stratigraphic sections (1560 m thick) spaced between 500 m and 100 m, were logged at 1:50 and 1:25 scale. The basal datum of the studied interval is the top of a MTC and the top marker bed is an extensive sandstone bed. Two units studied correspond to very coarse to fine-grained medium-bedded sandstones with abundant pebble-sized clasts (Unit1) and three thick plurimetric distinct beds of poorly-sorted, granular to medium-grained mud-rich sandstone matrix supporting polygenic gravels (Unit2). Distinct thick extensive beds in both units are intercalated with heterolithic successions of thin to medium-bedded very coarse- to coarse-grained or fine-grained sandstones, siltstones and mudstones. The sandstone beds in Unit 1 abruptly pinchout in the proximal part of study area. They are associated with evidence of erosion, sediment bypass and transformation of subaqueous sand-bearing flows. Stratigraphically, sandstone packages in the Unit 2 are increasingly more laterally extensive upwards in the succession. Thickness variations in these beds are related to compensational stacking. The research will inform studies in the architecture of deep-water successions above an uneven seabed inherited from the top of a MTC. The detailed analysis of exhumed examples that record depositional changes in the structure of the flow can lead to the development of predictive stratigraphic models which incorporate details and complexities observed in outcrop and can be applied for the evaluation of the quality of subsurface reservoirs.Fil: Privat, Aurélia. University of Leeds; Reino UnidoFil: Hodgson, David. University of Leeds; Reino UnidoFil: Peakall, Jeffrey. University of Leeds; Reino UnidoFil: Jackson, Christopher A. L.. University of Leeds; Reino UnidoFil: Schwarz, Ernesto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Investigaciones Geológicas. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Investigaciones Geológicas; Argentina2016 AAPG/SEG International Convention and ExhibitionBarcelonaEspañaAmerican Association of Petroleum GeologistsSociety of Exploration Geophysicist

Field responsive mechanical metamaterials.

Typically, mechanical metamaterial properties are programmed and set when the architecture is designed and constructed, and do not change in response to shifting environmental conditions or application requirements. We present a new class of architected materials called field responsive mechanical metamaterials (FRMMs) that exhibit dynamic control and on-the-fly tunability enabled by careful design and selection of both material composition and architecture. To demonstrate the FRMM concept, we print complex structures composed of polymeric tubes infilled with magnetorheological fluid suspensions. Modulating remotely applied magnetic fields results in rapid, reversible, and sizable changes of the effective stiffness of our metamaterial motifs

The Merluza Graben: How a failed spreading center influenced margin structure, and salt deposition and tectonics in the Santos Basin, Brazil

The relative timing between crustal extension and salt deposition can vary spatially along passive margin salt basins as continents unzip, or as the locus of extension shifts toward the embryonic ocean spreading center. Determining the relative timing of salt deposition, rifting, and seafloor spreading is often problematic due to the diachronous nature of rifting, the ability of salt to fill pre-existing topography, and the subsequent flow and deformation of that salt. We here use 2D PSDM seismic data and structural restorations to investigate the Merluza Graben, a large rift-related depocentre located in the southern, most proximal part of the Santos Basin, Brazil, along-strike of a failed spreading center, the Abimael Ridge. The graben is defined by up to 3.5km of base-salt relief along its basinward-bounding fault and internal base-salt horsts that are up to 1km high. This compartmentalizes deformation, producing intra-graben extensional and contraction salt structures, ramp-syncline basins, and expulsion rollovers, resulting in a remarkably different salt-tectonic structural style to that seen in the adjacent areas. We also conduct structural restorations to analyze the spatial and temporal evolution of salt-tectonic structural styles and the relationship this has to potential prolonged crustal extension in the Merluza Graben. This approach further constrains local variations in the relative timing of rifting and salt deposition, and the impact this has on salt tectonics along the margin. The results of our study can be applied to better understand the tectono-stratigraphic development of other salt-bearing rifted margins

Failure of interpolation in the intuitionistic logic of constant domains

This paper shows that the interpolation theorem fails in the intuitionistic logic of constant domains. This result refutes two previously published claims that the interpolation property holds.Comment: 13 pages, 0 figures. Overlaps with arXiv 1202.1195 removed, the text thouroughly reworked in terms of notation and style, historical notes as well as some other minor details adde

Population dynamics of rhesus macaques and associated foamy virus in Bangladesh.

Foamy viruses are complex retroviruses that have been shown to be transmitted from nonhuman primates to humans. In Bangladesh, infection with simian foamy virus (SFV) is ubiquitous among rhesus macaques, which come into contact with humans in diverse locations and contexts throughout the country. We analyzed microsatellite DNA from 126 macaques at six sites in Bangladesh in order to characterize geographic patterns of macaque population structure. We also included in this study 38 macaques owned by nomadic people who train them to perform for audiences. PCR was used to analyze a portion of the proviral gag gene from all SFV-positive macaques, and multiple clones were sequenced. Phylogenetic analysis was used to infer long-term patterns of viral transmission. Analyses of SFV gag gene sequences indicated that macaque populations from different areas harbor genetically distinct strains of SFV, suggesting that geographic features such as forest cover play a role in determining the dispersal of macaques and SFV. We also found evidence suggesting that humans traveling the region with performing macaques likely play a role in the translocation of macaques and SFV. Our studies found that individual animals can harbor more than one strain of SFV and that presence of more than one SFV strain is more common among older animals. Some macaques are infected with SFV that appears to be recombinant. These findings paint a more detailed picture of how geographic and sociocultural factors influence the spectrum of simian-borne retroviruses

Physical modelling of the interplay between salt-detached gravity gliding and spreading across complex rift topography, Santos Basin, offshore Brazil

The Santos Basin, offshore Brazil contains a complex set of salt-tectonic structures, the origins of which are debated, that is, the Albian Gap and the São Paulo Plateau (SPP). The Albian Gap is a ca. 450 km long, 60 km wide feature characterized by a post-Albian, counter-regional rollover overlying depleted Aptian salt, and in which the Albian is largely absent. The SPP, located immediately downdip, is defined by a pre-salt structural high overlain by ca. 2.5 km thick salt. Another prominent feature is the Merluza Graben, a rift-related depocentre that underlies the southern portion of the Albian Gap and displays significant (3-4 km) base-salt relief along its main faults. Two competing hypotheses have been proposed to explain the kinematics of these provinces. One invokes post-Albian extension in the Albian Gap and kinematically-linked contraction in the SPP. The other invokes post-Albian salt expulsion in the Albian Gap and salt inflation in the SPP. Recent studies, however, suggest these processes likely alternate in time and space, contributing nearly equally to the evolution of these domains. We apply 3D physical modelling to (i) test this hypothesis; and (ii) to more generally understand how gravity gliding and spreading over three-dimensionally variable base-salt relief control regional salt tectonics. The results show a similar salt-related evolution and structural styles to those proposed in the most recent studies. They also (i) explain the origin of the ca. 25 km wide diapir precursor of the Albian Gap by early salt inflation against base-salt steps; (ii) show that normal faults with different polarities and rollover types form due to the interplay between gliding and spreading over different base-salt domains and (iii) provide a mechanism for the origin of strata encased within salt structures. This improves our understanding of the distribution and origin of salt-related structural styles in worldwide salt basins

Functional Movement Screentm Scores in Collegiate Track and Field Athletes in Relation to Injury Risk and Performance

Purpose: The purpose of this study was to examine the relationship between Functional Movement Screentm (FMS) scores, injury rate, and performance in collegiate track and field athletes. Methods: Forty seven male (n=17) and female (n=30) competitive track and field athletes at an NCAA Division I university volunteered for this study. As part of their regular team assessment, the athletes were evaluated on three separate occasions using the FMS tool: in August, one week prior to the start of university organized practice for the fall (T1); in December, one week prior to the end of the fall academic semester (T2); and in March, the week following the conclusion of the indoor competition season (T3). The FMS consists of the performance of seven fundamental movement patterns that are evaluated and scored by a trained professional. For each time point, athletes were divided into two categories based on total FMS score (≤14 and ≥15). Throughout the competitive season, injuries were tracked and categorized as either mild (no loss of practice or competition time) or moderate/severe (loss of practice or competition time). As part of an ongoing injury prevention program, athletes performed generalized corrective exercises for 15 min 2-3 times per week. The performance in the last event of the season (conference meet) was also recorded. Results: Average FMS scores significantly (p\u3c0.05) decreased across the three time points (Mean ± SD, T1: 15.5 ± 2.2, T2: 14.9 ± 1.8, T3: 14.7 ± 1.6) despite that generalized corrective exercises were performed. Analyses of results found no association between FMS scores and likelihood to sustain a moderate/severe injury. Athletes with a score of ≤14 on the FMS at T1 were 3.1 times more likely not to place in the top 8 at the conference meet. 53% of the athletes who had a score of ≥15 at T1 placed in the top 8 at the meet while only 27% of athletes with a score of ≤14 at T1 placed in the top 8 at the meet. Conclusion: FMS scores ≤14 indicate reduced performance ability but not increased likelihood of injury in track and field athletes