ARM-Cortex M3-Based Two-Wheel Robot for Assessing Grid Cell Model of Medial Entorhinal Cortex: Progress towards Building Robots with Biologically Inspired Navigation-Cognitive Maps

This article presents the implementation and use of a two-wheel autonomous robot and its effectiveness as a tool for studying the recently discovered use of grid cells as part of mammalian’s brains space-mapping circuitry (specifically the medial entorhinal cortex). A proposed discrete-time algorithm that emulates the medial entorhinal cortex is programed into the robot. The robot freely explores a limited laboratory area in the manner of a rat or mouse and reports information to a PC, thus enabling research without the use of live individuals. Position coordinate neural maps are achieved as mathematically predicted although for a reduced number of implemented neurons (i.e., 200 neurons). However, this type of computational embedded system (robot’s microcontroller) is found to be insufficient for simulating huge numbers of neurons in real time (as in the medial entorhinal cortex). It is considered that the results of this work provide an insight into achieving an enhanced embedded systems design for emulating and understanding mathematical neural network models to be used as biologically inspired navigation system for robots

Self-attraction effect and correction on three absolute gravimeters

The perturbations of the gravitational field due to the mass distribution of an absolute gravimeter have been studied. The so called Self Attraction Effect (SAE) is crucial for the measurement accuracy, especially for the International Comparisons, and for the uncertainty budget evaluation. Three instruments have been analysed: MPG-2, FG5-238 and IMPG-02. The SAE has been calculated using a numerical method based on FEM simulation. The observed effect has been treated as an additional vertical gravity gradient. The correction (SAC) to be applied to the computed g value has been associated with the specific height level, where the measurement result is typically reported. The magnitude of the obtained corrections is of order 1E-8 m/s2.Comment: 14 pages, 8 figures, submitted to Metrologi

Performance of translucent optical networks under dynamic traffic and uncertain physical-layer information

This paper investigates the performance of translucent Optical Transport Networks (OTNs) under different traffic and knowledge conditions, varying from perfect knowledge to drifts and uncertainties in the physical-layer parameters. Our focus is on the regular operation of a translucent OTN, i.e., after the dimensioning and regenerator placement phase. Our contributions can be summarized as follows. Based on the computation of the Personick’s Q factor, we introduce a new methodology for the assessment of the optical signal quality along a path, and show its application on a realistic example. We analyze the performance of both deterministic and predictive RWA techniques integrating this signal quality factor Q in the lightpath computation process. Our results confirm the effectiveness of predictive techniques to deal with the typical drifts and uncertainties in the physical-layer parameters, in contrast to the superior efficacy of deterministic approaches in case of perfect knowledge. Conversely to most previous works, where all wavelengths are assumed to have the same characteristics, we examine the case when the network is not perfectly compensated, so the Maximum Transmission Distance (MTD) of the different wavelength channels may vary. We show that blocking might increase dramatically when the MTD of the different wavelength channels is overlooked.Postprint (published version

Techno-economic benchmarking of NOBEL solutions for end-to-end broadband communications (invited paper)

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Diacutaneous fibrolysis versus passive stretching after articular immobilisation : muscle recovery and extracellular matrix remodelling

Introduction Atrophy and muscle shortening due to articular immobilisation are common problems in musculoskeletal rehabilitation. Muscle stretching mechanical stimuli might be considered as the golden standard procedure to improve muscle flexibility in rehabilitation. Muscle stretching generates mechanotransduction, potentiating specific gene expression and promotes sarcomerogenesis and extracellular matrix remodelling on shortened and atrophied muscles. Hypothesis Diacutaneous fibrolysis, like stretching, uses an external force to stress connective and muscle tissues mechanically to treat muscle shortening; thus, it is widely used in clinical practice even if there is no evidence to support it. Considering this subject, we have hypothesised that diacutaneous fibrolysis can generate mechanotransduction, affecting muscle hypertrophy and extracellular matrix remodelling after immobilisation. Evaluation of hypothesis We have designed a laboratory experimental study with a sample of 50 rats. The sample was randomly divided into five groups: Control group (n = 10) with non–immobilised rats; 3–week immobilisation group (n = 10); 3–week immobilisation/3–week non–immobilisation group (n = 10);3–week immobilisation/3–week stretching group (n = 10); and 3–week immobilisation/3–week diacutaneous fibrolysis group (n = 10). All rats had their left tibiotarsal joint immobilised in maximum plantar flexion with the orthotics for 3 consecutive weeks. After the immobilisation period, the intervention groups received their respective intervention on their left triceps suralis for 3 weeks. Dependent variables of the study were sarcomere analysis, polymerase chain reaction, connective tissue density, collagen birefringence and matrix metalloproteinases. Statistical analysis was performed using analysis of variance and Duncan post hoc test was applied for differences between groups. For all calculations, a 5% (p < 0.05) significance level was established. Conclusion If the hypothesis is confirmed, the present study might provide evidence to support the use of this physical therapy resource widely used to treat muscle dysfunctions