2,042 research outputs found
Compact-bounded topological groups
We will study two subclasses of the class of feebly compact spaces in the
class of (para)topological groups, the compact-bounded and weakly
compact-bounded spaces, both introduced by J. Angoa, Y. F. Ortiz-Castillo and
A. Tamariz-Mascar\'ua in [4]. Also, we will study the -weakly
compact-bounded subsets of a topological space .Comment: 18 page
3D multi-robot patrolling with a two-level coordination strategy
Teams of UGVs patrolling harsh and complex 3D environments can experience interference and spatial conflicts with one another. Neglecting the occurrence of these events crucially hinders both soundness and reliability of a patrolling process. This work presents a distributed multi-robot patrolling technique, which uses a two-level coordination strategy to minimize and explicitly manage the occurrence of conflicts and interference. The first level guides the agents to single out exclusive target nodes on a topological map. This target selection relies on a shared idleness representation and a coordination mechanism preventing topological conflicts. The second level hosts coordination strategies based on a metric representation of space and is supported by a 3D SLAM system. Here, each robot path planner negotiates spatial conflicts by applying a multi-robot traversability function. Continuous interactions between these two levels ensure coordination and conflicts resolution. Both simulations and real-world experiments are presented to validate the performances of the proposed patrolling strategy in 3D environments. Results show this is a promising solution for managing spatial conflicts and preventing deadlocks
Manuel practique: Cartographie numérique des sols
Ce document aborde les étapes du processus et les outils utilisés dans le cours d'initiation à l'utilisation de la cartographie numérique des sols réalisé par le Centre International d'Agriculture Tropical (CIAT) dans le cadre du projet «Cultures innovantes et technologies agricoles terrestres à Haiti» et financé par le Fond International de Développement Agricole (FIDA – sigle anglais IFAD
El primer cráneo fósil de Chelus (Pleurodira: Chelidae; tortugas del género Matamata) del Mioceno temprano de Colombia
Here we describe the first fossil skull so far known for the turtle genus Chelus from the early Miocene (~ 16 m.y.), Castilletes Formation, Alta Guajira Peninsula, Cocinetas basin, Colombia. The skull is partially preserved, including most of the basicranium (pteygoid-bassioccipital bones) and the roof elements including the parietal, pterygoid and portions of the squamosal, supraoccipital and the most dorsal quadrate. The skull is preserved in three dimensions, without evidence of crushing, allowing the observation of the internal braincase morphology using microcomputer tomography. Comparisons with the skull of the only extant species for the genus Chelus fimbriata (Matamata turtle) allow us to conclude that for the last 16 million years the morphology of the skull for this genus has remained almost unvarying, with only a slightly higher compression of the most anterior braincase exhibited by the extant species. Due to its fragmentary condition, a more refined identification beyond the genus (Chelus sp.) is not possible; however, the overall skull design indicates that the fossil species could also have had the same ecological and dietary adaptations as its extant relative
The first Oligocene sea turtle (Pan-Cheloniidae) record of South America
The evolution and occurrence of fossil sea turtles at the Pacific margin of South America is poorly known and restricted to Neogene (Miocene/Pliocene) findings from the Pisco Formation, Peru. Here we report and describe the first record of Oligocene (late Oligocene, ~24 Ma) Pan-Cheloniidae sea turtle remains of South America. The fossil material corresponds to a single, isolated and well-preserved costal bone found at the Montañita/Olón locality, Santa Elena Province, Ecuador. Comparisons with other Oligocene and extant representatives allow us to confirm that belongs to a sea turtle characterized by: lack of lateral ossification, allowing the dorsal exposure of the distal end of ribs; dorsal surface of bone sculptured, changing from dense vermiculation at the vertebral scute region to anastomosing pattern of grooves at the most lateral portion of the costal. This fossil finding shows the high potential that the Ecuadorian Oligocene outcrops have in order to explore the evolution and paleobiogeography distribution of sea turtles by the time that the Pacific and the Atlantic oceans were connected via the Panama basin
Immune system activation by natural products and complex fractions: a network pharmacology approach in cancer treatment.
Natural products and traditional herbal medicine are an important source of alternative bioactive compounds but very few plant-based preparations have been scientifically evaluated and validated for their potential as medical treatments. However, a promising field in the current therapies based on plant-derived compounds is the study of their immunomodulation properties and their capacity to activate the immune system to fight against multifactorial diseases like cancer. In this review we discuss how network pharmacology could help to characterize and validate natural single molecules or more complex preparations as promising cancer therapies based on their multitarget capacities
New findings of Pleistocene fossil turtles (Geoemydidae, Kinosternidae and Chelydridae) from Santa Elena Province, Ecuador
New Pleistocene fossilized turtle remains from five localities of western Ecuador (Santa Elena Province) are described here. All these shell (carapace and plastron) fossil remains come from the Tablazo Formation and belong to three different lineages of cryptodires ("hidden-necked" turtles). The most abundant remains belong to geoemydids, attributed here to the genus Rhinoclemmys (indeterminate species). Less abundant in occurrence are the kinosternidids, attributed to Kinosternon (indeterminate species), and the first fossil record of chelydrids, Chelydra (indeterminate species), in the entirety of Central and South America
Sparse 3D Point-cloud Map Upsampling and Noise Removal as a vSLAM Post-processing Step: Experimental Evaluation
The monocular vision-based simultaneous localization and mapping (vSLAM) is
one of the most challenging problem in mobile robotics and computer vision. In
this work we study the post-processing techniques applied to sparse 3D
point-cloud maps, obtained by feature-based vSLAM algorithms. Map
post-processing is split into 2 major steps: 1) noise and outlier removal and
2) upsampling. We evaluate different combinations of known algorithms for
outlier removing and upsampling on datasets of real indoor and outdoor
environments and identify the most promising combination. We further use it to
convert a point-cloud map, obtained by the real UAV performing indoor flight to
3D voxel grid (octo-map) potentially suitable for path planning.Comment: 10 pages, 4 figures, camera-ready version of paper for "The 3rd
International Conference on Interactive Collaborative Robotics (ICR 2018)
El diagnóstico por imagen de las hernias de la pared abdominal
Abdominal wall hernias in their different modalities form a group of commonly encountered surgical conditions. They vary in their presentation from asymptomatic to life threatening emergencies. Clinical history and physical examination are the primary methods for diagnosis, however in a significant percentage of patients, a normal physical examination can be found. Due to this, diagnostic imaging has been gaining attention in recent years, which in addition to identifying the cases of abdominal hernias with normal physical examination, provide additional relevant data. In this article we review available literature regarding the usefulness of diagnostic imaging such as herniography, ultrasound (US), computed tomography (CT) and magnetic resonance imaging (MRI) for the diagnosis of abdominal wall hernias. CT and ultrasound are the main modalities used for the diagnosis and characterization of the hernia defect. CT is recommended when there is uncertainty in the diagnosis after the physical examination or initial ultrasound, or as a first option if complications are suspected. Evaluation using imaging is important both as a diagnostic tool and for an adequate anatomical characterization in patients with suspected abdominal wall hernias. © 2019 Sociedad Hispanoamericana de Hernia. Publicado por Arán Ediciones, S.L. Todos los derechos reservados
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