Search results for " Navigation"
showing 10 items of 138 documents
Attention-based environment perception in autonomous robotics
2007
This paper describes a robotic architecture that uses visual attention mechanisms for autonomous navigation in unknown indoor environments. A foveation mechanism based on classical bottom-up gaze shifts allows the robot to autonomously select landmarks, defined as salient points in the camera images. Landmarks are memorized in a behavioral fashion, coupling sensing and acting to achieve a representation view and scale independent. Selected landmarks are stored in a topological map; during the navigation a top-down mechanism controls the attention system to achieve robot localization. Experiments and results show that our system is robust to noise and odometric errors, being at the same time…
Statistical analysis of latency outcomes in behavioral experiments
2011
In experimental designs of animal models, memory is often assessed by the time for a performance measure to occur (latency). Depending on the cognitive test, this may be the time it takes an animal to escape to a hidden platform (water maze), an escape tunnel (Barnes maze) or to enter a dark component (passive avoidance test). Latency outcomes are usually statistically analyzed using ANOVAs. Besides strong distributional assumptions, ANOVA cannot properly deal with animals not showing the performance measure within the trial time, potentially causing biased and misleading results. We propose an alternative approach for statistical analyses of latency outcomes. These analyses have less distr…
A Morphosyntactical Complementary Structure for Searching and Browsing
2006
This paper is a proposal for the construction of a pseudo-net built with precisely defined tokens describing the content and structure of the original WWW. This construction is derived by morphosyntactical analysis and should be structured with a post-processing mechanism. It is provided also an in-depth analysis of requirements and hypothesis to be stated to accomplish with this goal. An in-depth analysis of requirements and hypothesis to be stated to accomplish this goal is also provided. Such derived structure could act as an alternate network theme organization with a compacted version of the original web material. This paper does not describe nor study the post-processing approaches. I…
Space-borne frequency comb metrology
2016
Precision time references in space are of major importance to satellite-based fundamental science, global satellite navigation, earth observation, and satellite formation flying. Here we report on the operation of a compact, rugged, and automated optical frequency comb setup on a sounding rocket in space under microgravity. The experiment compared two clocks, one based on the optical D2 transition in Rb, and another on hyperfine splitting in Cs. This represents the first frequency comb based optical clock operation in space, which is an important milestone for future satellite-based precision metrology. Based on the approach demonstrated here, future space-based precision metrology can be i…
Spatial learning and expression patterns of PP1 mRNA in mouse hippocampus.
2009
<i>Background:</i> Synaptic plasticity is believed to be the major cellular basis for learning and memory. Protein phosphorylation is a key process involved in changes in the efficacy of neurotransmission. In long-term changes synaptic plasticity is followed by structural plasticity and protein de novo synthesis. Such mechanisms are believed to build the basis of hippocampal learning and memory investigated in the Morris water maze (MWM) task. To examine the role of dephosphorylation during that model for spatial learning, we analyzed protein phosphatase 1 (PP1) expression in the hippocampus of mice at various stages of the task and in two groups with different learning abilitie…
On the coupling between agent internal and agent/ environmental dynamics: Development of spatial representations in evolving autonomous robots
2008
In this article we describe how a population of evolving robots can autonomously develop forms of spatial representation which allow them to self-localize and to discriminate different locations of their environment by integrating sensory-motor information over time. The evolving robots also display a remarkable ability to generalize their skill in new environmental conditions that they have never experienced before. The analysis of the obtained results indicates that the evolved robots come up with simple and robust solutions that exploit quasi-periodic limit cycle dynamics emerging from the coupling between the robot/environmental dynamics and a robot's internal dynamics. More specifical…
Exploring the application of the navigation model with people experiencing homelessness: a scoping review
2022
People experiencing homelessness are known to be at risk of disproportionately poor health outcomes and often face barriers in accessing healthcare. Patient navigation (PN) has been identified as a way to address health disparities and engage underserved populations with healthcare services . This scoping review aims to understand how PN models have been utilized with people experiencing homelessness and other comparable populations to date and more specifically identify (a) the defining features, (b) the barriers and facilitators in implementation, and (c) the outcomes associated with PN models. Database searches were conducted in Web of Science, PubMed and SCOPUS on 15th June 2021 and 21 …
A vision agent for mobile robot navigation in time-variable environments
2002
We present an architecture for mobile robot navigation based on Bayesian networks. The architecture allows a robot to plan the correct path inside an environment with dynamic obstacles. Interactions between the robot and the environment are based on a powerful vision agent. The results of simulations, showing the effectiveness of the approach, are described.
Global Navigation Satellite Systems And Services
2008
This chapter introduces the concept of Satellite Navigation in the context of space infrastructures and technologies that can contribute for improvement of life on Earth. It includes a review of the motivations for developing a satellite navigation system, and the applications and services these systems have in daily life. Furthermore, currently existing Global Navigation Satellite Systems (GPS and GLONASS) and other GNSS systems under development (GALILEO) are described from different perspectives: from the technical and architectural aspects to the ways chosen to finance their development and operations. To round up this chapter, an analysis of the expected trends in GNSS systems is prese…
Web accessibility for visual disabled: An expert evaluation of the Inclusite&#x00AE; solution
2012
This study analyzes web accessibility problems for people with visual disability and presents the results of testing a prototype of Inclusite® system, an access solution designed to facilitate web navigation for people with visual disability, consisting of a navigation interface through keyboard and speech synthesis. An expert typhlotechnologist conducts a navigation test in three sessions evaluating the prototype positively and suggesting aspects for improvement. The interface provides web access as a service, the access solution is hosted in the website, so that the user can perform navigation using a different computer (not the own) which does not have his usual technical aids, helping t…