Search results for " Navigation"
showing 10 items of 138 documents
Effect of a dominant-negative form of ADAM10 in a mouse model of Alzheimer's disease.
2009
The alpha-secretase cleaves in the non-amyloidogenic pathway the amyloid-beta protein precursor (AbetaPP) within the region of the amyloid-beta peptides to prevent their formation and aggregation in the brain. Members of the ADAM family (a disintegrin and metalloprotease) are the main candidates for physiologically relevant alpha-secretases. We recently demonstrated that overexpression of ADAM10 in mice transgenic for human AbetaPP (ADAM10 x APP[V717I]) alleviated functional deficits related to Alzheimer's disease. To further demonstrate that this is due to the specific activity of alpha-secretase, we characterized mice overexpressing an inactive form of ADAM10 (ADAM10[E384A]; ADAM10-dn). T…
Path Following in Non-Visual Conditions.
2018
Path-following tasks have been investigated mostly under visual conditions, that is when subjects are able to see both the path and the tool, or limb, used for navigation. Moreover, only basic path shapes are usually adopted. In the present experiment, participants must rely exclusively on continuous, non-speech, and ecological auditory and vibrotactile cues to follow a path on a flat surface. Two different, asymmetric path shapes were tested. Participants navigated by moving their index finger over a surface sensing position and force. Results show that the different non-visual feedback modes did not affect the task's accuracy, yet they affected its speed, with vibrotactile feedback causin…
Stereotactic biopsies guided by an optical navigation system: technique and clinical experience.
2002
Frame-based stereotactic biopsies are time-consuming procedures making necessary head fixation in a ring, explicit coordinate calculation and setting of the parameters. Frameless systems make many of these intermediate steps unnecessary, impose less mechanical restrictions regarding access to the lesions, and with slight modifications can be used to perform stereotactic biopsies. A special adaptation designed to fix the holder and the biopsy instrument is described. The neuronavigation optical tracking system of Radionics was used. CT scans were performed with 6 skin markers. Calibration was performed after head fixation in the Mayfield clamp. Mean calibration error was 2.19 +/- 0.81 mm. Th…
A Neural Solution for a Mobile Robot Navigation into Unknown Indoor Environments Using Visual Landmarks
1998
In this paper we present a neural solution for a mobile robot navigation into unknown indoor environments by using landmarks. Robot navigation task is implemented by two groups of processes based on MLP neural networks classifiers: a Low Level Vision System performs obstacle avoidance and corridor following, while an High Level Vision System extracts landmarks contents and performs goal directed navigation. A path-planner manages the two navigation systems and interacts with the robot hardware. The proposed solution is very strong and flexible and can be used to drive a mobile robot in real indoor environments. In the paper experimental results are also reported.
A hybrid observer for localization of mobile vehicles with asynchronous measurements
2019
The aim of this paper is the design of a hybrid nonlinear observer for mobile vehicles. The main problem is that position and velocity measurements are provided with a very low frequency, and the time between two consecutive measurements could be not constant, but it could vary randomly within a certain interval of time. For this reason the proposed observer has been contextualized in the hybrid systems framework. The convergence analysis of the estimation error has been carried out, and the sensitivity analysis has been performed in order to evaluate the bound of the estimation error when the measurements are biased and/or noisy. Simulation and experimental results, carried out on a mobile…
A new airborne tandem platform for collocated measurements of microphysical cloud and radiation properties
2009
Abstract. A new airborne tandem measurement platform for cloud-radiation interaction studies is introduced in this paper. It consists of a Learjet 35A research aircraft and the AIRcraft TOwed Sensor Shuttle (AIRTOSS), which is an instrumented drag-body towed by the Learjet. Currently, the AIRTOSS is instrumented with a Cloud Imaging Probe (CIP) for measuring cloud microphysical properties and an Inertial Navigation System (INS) for measurements of flight attitudes. The cable dragging AIRTOSS can be as long as four kilometres. Thus, truly collocated measurements in two altitudes above, in, and below clouds can be obtained. Results from first test flights with Learjet and AIRTOSS are reported…
Ebselen prevents chronic alcohol-induced rat hippocampal stress and functional impairment
2007
Background: Most of the previously published data suggest a role for oxidative or nitrosative stress in ethanol-induced nervous system damage. Moreover, ethanol is able to impair learning abilities in adult mammalian brain, a process suggested to be directly related to hippocampal neurogenesis. Ebselen, a synthetic compound with antioxidant properties, is able to prevent ethanol-induced impairment of neurogenesis in adult rats. The aim of the present work was to further demonstrate the ability of ebselen to prevent biochemical alterations, and preserve long-term potentiation (LTP) and learning abilities, in the hippocampus of chronic alcoholic adult rats. Methods: Biochemical markers of oxi…
Endo-neuro-sonography: Anatomical aspects of the basal cisterns
1997
SummaryTo evaluate the usefulness of transendoscopic sonography, two sono catheters of 6F diameter were studied in 15 fresh specimens. A precise imaging was seen of well known anatomical structures. An additional dimension in endoscopy was also obtained as the sono added to the endo view a transversal scan like a mini CT at the tip of the probe. The guiding characteristic of this imaging technique, which is in real time and on line, was also experienced. These observations offer such interesting prospects for use in minimally invasive neurosurgery that further development and clinical experience seem to be justified.
ANTECEDENTES DEL ABASTECIMIENTO DE MADERA EN LA RIBERA DEL JÚCAR
2015
Wood's supply was an essential aspect for the Kingdom of Valencia during the medieval centuries. The large plain around the coast and the forest shortage caused, firstly, the development of supplying strategies and, secondly, the creation of specifical orders in order to guarantee it. In that sense, Júcar and its tributary Cabriel played an important role in the trunks traffic coming from the mountains of Cuenca. Also, the surrounding countryside was primordial in the procedure. In this article we are going to analyse the methods in use in the Almoravid period and the circumstances of the trunks navigation on the river after the conquest. El abastecimiento de madera fue un aspecto fundament…
Enhanced Spatial Navigation Skills in Sequence-Space Synesthetes
2018
Contains fulltext : 219554.pdf (Publisher’s version ) (Closed access) Individuals with sequence-space synesthesia (SSS) perceive sequences like months, days and numbers in certain spatial arrangements. Several cognitive benefits have been associated with SSS, such as enhanced mental rotation, more vivid visual imagery and an advantage in spatial processing. The current study aimed to further investigate these cognitive benefits, focusing on spatial navigation skills, to explore if their enhanced sensitivity to spatial relations is reflected in enhanced navigational performance. Synesthetes were distinguished from controls by means of a questionnaire, a consistency test and drawings. A virtu…