Optimal UAV Path Planning for Tracking a Moving Ground Vehicle with a Gimbaled Camera

This research develops a path planning algorithm that autonomously controls a UAV to provide convoy overwatch. The optimization algorithm determines the best path to y through developing a cost function that minimizes the control effort of the UAV and the deviation from a desired slant range. A heuristic-based algorithm was developed and implemented on the autopilot to approximate the optimal solution. In flight test, the UAV successfully tracked a moving ground vehicle by continually placing the UAV\u27s loiter point directly above the ground vehicle\u27s current location. This method was called the \follow-me mode and provided the baseline for real-world UAV convoy overwatch. The follow-me mode resulted in a cost function value that was 113 times greater than the optimal path. Through an in-depth analysis, the heuristic-based approach reduced this ratio down to only 7.5 times greater than the optimal path. The data collected shows tremendous promise for improving autonomous UAV performance through optimal control techniques

Geochronology and geochemistry of the northern Scotia Sea: a revised interpretation of the North and West Scotia ridge junction

Understanding the tectonic evolution of the Scotia Sea is critical to interpreting how ocean gateways developed during the Cenozoic and their influence on ocean circulation patterns and water exchange between the Atlantic and Southern oceans. We examine the geochronology and detrital age history of lithologies from the prominent, submerged Barker Plateau of the North Scotia Ridge. Metasedimentary rocks of the North Scotia Ridge share a strong geological affinity with the Fuegian Andes and South Georgia, indicating a common geological history and no direct affinity to the Antarctic Peninsula. The detrital zircon geochronology indicates that deposition was likely to have taken place during the mid – Late Cretaceous. A tonalite intrusion from the Barker Plateau has been dated at 49.6 ±0.3Ma and indicates that magmatism of the Patagonian–Fuegian batholith continued into the Eocene. This was coincident with the very early stages of Drake Passage opening, the expansion of the proto Scotia Sea and reorganization of the Fuegian Andes. The West Scotia Ridge is an extinct spreading centerthat shaped the Scotia Sea and consists of seven spreading segments separated by prominent transform faults. Spreading was active from 30–6Ma and ceased with activity on the W7 segment at the junction with the North Scotia Ridge. Reinterpretation of the gravity and magnetic anomalies indicate that the architecture of the W7 spreading segment is distinct to the other segments of the West Scotia Ridge. Basaltic lava samples from the eastern flank of the W7 segment have been dated as Early – mid Cretaceous in age (137–93Ma) and have a prominent arc geochemical signature indicating that seafloor spreading did not occur on the W7 segment. Instead the W7 segment is likely to represent a downfaulted block of the North Scotia Ridge of the Fuegian Andes continental margin arc, or is potentially related to the putative Cretaceous Central Scotia Sea

Spectroscopic and Mechanistic Studies of Heterodimetallic Forms of Metallo-β-lactamase NDM-1

In an effort to characterize the roles of each metal ion in metallo-β-lactamase NDM-1, heterodimetallic analogues (CoCo-, ZnCo-, and CoCd-) of the enzyme were generated and characterized. UV–vis, 1H NMR, EPR, and EXAFS spectroscopies were used to confirm the fidelity of the metal substitutions, including the presence of a homogeneous, heterodimetallic cluster, with a single-atom bridge. This marks the first preparation of a metallo-β-lactamase selectively substituted with a paramagnetic metal ion, Co(II), either in the Zn1 (CoCd-NDM-1) or in the Zn2 site (ZnCo-NDM-1), as well as both (CoCo-NDM-1). We then used these metal-substituted forms of the enzyme to probe the reaction mechanism, using steady-state and stopped-flow kinetics, stopped-flow fluorescence, and rapid-freeze-quench EPR. Both metal sites show significant effects on the kinetic constants, and both paramagnetic variants (CoCd- and ZnCo-NDM-1) showed significant structural changes on reaction with substrate. These changes are discussed in terms of a minimal kinetic mechanism that incorporates all of the data

What traits are carried on mobile genetic elements, and why?

Although similar to any other organism, prokaryotes can transfer genes vertically from mother cell to daughter cell, they can also exchange certain genes horizontally. Genes can move within and between genomes at fast rates because of mobile genetic elements (MGEs). Although mobile elements are fundamentally self-interested entities, and thus replicate for their own gain, they frequently carry genes beneficial for their hosts and/or the neighbours of their hosts. Many genes that are carried by mobile elements code for traits that are expressed outside of the cell. Such traits are involved in bacterial sociality, such as the production of public goods, which benefit a cell's neighbours, or the production of bacteriocins, which harm a cell's neighbours. In this study we review the patterns that are emerging in the types of genes carried by mobile elements, and discuss the evolutionary and ecological conditions under which mobile elements evolve to carry their peculiar mix of parasitic, beneficial and cooperative genes

Morphological and geological features of Drake Passage, Antarctica, from a new digital bathymetric model

The Drake Passage is an oceanic gateway of about 850 km width located between South America and the Antarctic Peninsula that connects the southeastern Pacific Ocean with the southwestern Atlantic Ocean. It is an important gateway for mantle flow, oceanographic water masses, and migrations of biota. This sector developed within the framework of the geodynamic evolution of the Scotia Arc, including continental fragmentation processes and oceanic crust creation, since the oblique divergence of the South American plate to the north and the Antarctic plate to the south started in the Eocene. As a consequence of its complex tectonic evolution and subsequent submarine processes, as sedimentary infill and erosion mainly controlled by bottom currents and active tectonics, this region shows a varied physiography. We present a detailed map of the bathymetry and geological setting of the Drake Passage that is mainly founded on a new compilation of precise multibeam bathymetric data obtained on 120 cruises between 1992 and 2015, resulting in a new Digital Bathymetric Model with 200 × 200 m cell spacing. The map covers an area of 1,465,000 km2 between parallels 52°S and 63°S and meridians 70°W and 50°W at scale 1:1,600,000 allowing the identification of the main seafloor features. In addition, the map includes useful geological information related to magnetism, seismicity and tectonics. This work constitutes an international cooperative effort and is part of the International Bathymetric Chart of the Southern Ocean project, under the Scientific Committee on Antarctic Research umbrella

Morphological and geological features of Drake Passage, Antarctica, from a new digital bathymetric model

The Drake Passage is an oceanic gateway of about 850km width located between South America and the Antarctic Peninsula that connects the southeastern Pacific Ocean with the southwestern Atlantic Ocean. It is an important gateway for mantle flow, oceanographic water masses, and migrations of biota. This sector developed within the framework of the geodynamic evolution of the Scotia Arc, including continental fragmentation processes and oceanic crust creation, since the oblique divergence of the South American plate to the north and the Antarctic plate to the south started in the Eocene. As a consequence of its complex tectonic evolution and subsequent submarine processes, as sedimentary infill and erosion mainly controlled by bottom currents and active tectonics, this region shows a varied physiography. We present a detailed map of the bathymetry and geological setting of the Drake Passage that is mainly founded on a new compilation of precise multibeam bathymetric data obtained on 120 cruises between 1992 and 2015, resulting in a new Digital Bathymetric Model with 200x200 m cell spacing. The map covers an area of 1,465,000km2 between parallels 52°S and 63°S and meridians 70°W and 50°W at scale 1:1,600,000 allowing the identification of the main seafloor features. In addition, the map includes useful geological information related to magnetism, seismicity and tectonics. This work constitutes an international cooperative effort and is part of the International Bathymetric Chart of the Southern Ocean project, under the Scientific Committee on Antarctic Research umbrella