368 research outputs found

    Basic language learning in artificial animals

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    We explore a general architecture for artificial animals, or animats, that develops over time. The architecture combines reinforcementlearning, dynamic concept formation, and homeostatic decision-making aimed at need satisfaction. We show that thisarchitecture, which contains no ad hoc features for language processing, is capable of basic language learning of three kinds: (i)learning to reproduce phonemes that are perceived in the environment via motor babbling; (ii) learning to reproduce sequences ofphonemes corresponding to spoken words perceived in the environment; and (iii) learning to ground the semantics of spoken wordsin sensory experience by associating spoken words (e.g. the word “cold”) to sensory experience (e.g. the activity of a sensor forcold temperature) and vice versa

    Partitioning and purification of polygalacturonases produced by Aspergillus niger URM 5162 using PEG-phosphate in an aqueous two-phase system

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    Pectinases, or pectinolytic enzymes, are naturally produced by plants, filamentous fungi, bacteria and yeasts. The pectinases are of great importance to clarify and reduce viscosity in fruit juices, improving and increasing tbe filtration efficiency. When used in the crushing of grapes or wine must improve juice extraction, reduce the time to clarify and enhance tbe content ofterpenes in wine. The filamentous fungi most frequently used fur industrial purposes because as much as 90% ofthe enzyme can be excreted into the culture medium. The partitioning and purification of polygalacturonases (PG) produced by Aspergillus niger URM 5162 were investigated in aqueous two-phase systems (ATPS), furmed by polyetbylene glycol and phosphate salts (PE(ijlhosphate). To evaluate the effect oftbe 4 independent variables- molar mass ofpolyetbylene glycol (PEG) (400-8000 g1nol MPEG), PEG concentration (12.5-17.5%, w/w- CPEG), phosphate concentration (15-25%, ...W, CPHOS) and pH (6.0, 8.0) - on the 3 response variables: partition coefficient (K), activity yield (Y) and purification fàctor (PF), a fuctorial design (24) was used. The endo-polygalacturonases (endo-PG) were prefurentially partitioned in tbe top phase. For endo-PG, the highest values for the response variables K, Y and PF of 1.23, 74.04% and 8.18, respectively, were obtained for a CPEG of 12.5% (...W), MPEG of8000 g1nol, and CPHOS of25% (w/w) at pH 6.0. Also, exo-polygalacturonases (exo-PG) were preferentially partitioned in the top phase. ln tbis case, the highest values ofK (2.40), Y (33.33%), and PF (1.98) were obtained with a MPEG of 8000 g1nol, CPEG of 12.5% (...W), and CPHOS of25% (...W) at pH 6.0. ln both cases, MPEG had a positive influence on K, Y and PF. The conditions ofMPEG 8000 g1nol, CPEG of 12.5% (...W), and CPHOS of25% (...W) at pH 6.0 were considered the most suitable for tbe purification of PG produced by A. niger URM 5162. Furtbermore, MPEG and CPHOS were the most important independent variables. The PEG/phosphate system is a useful cost-effective altemative for PG purification

    Determination of the sensitized zone extension in welded AISI 304 stainless steel using non-destructive electrochemical techniques

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    Extension of sensitized zone (SZ) in welded AISI 304 stainless steel was determined by two non-destructive electrochemical tests: double loop electrochemical potentiokinetic reactivation technique (DLEPR) and local electrochemical impedance spectroscopy (LEIS). Welding was carried out using the shielded metal arc with two selected welding energies: the first one (0.7 kJ mm¡1) does not promote the sensitization of the 304 steel and it constitutes the reference sample and the second one (2.2 kJ mm¡1) which leads to the precipitation of chromium carbides in the grain boundaries after the welding process. The non-destructive DLEPR and LEIS tests allowed the length of the SZ to be determined and a good agreement between the two techniques and the microstructure of the two welded samples was shown. The presence of an inductive loop on the local impedance diagrams seems to reflect a galvanic coupling between the weld string (anode) and the welded stainless steel plates (cathode) which will be very prejudicial to a good corrosion resistance of the welded system. The results showed that the two electrochemical tests could be applied in practical cases in industrial field

    Scaling of Brain Metabolism with a Fixed Energy Budget per Neuron: Implications for Neuronal Activity, Plasticity and Evolution

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    It is usually considered that larger brains have larger neurons, which consume more energy individually, and are therefore accompanied by a larger number of glial cells per neuron. These notions, however, have never been tested. Based on glucose and oxygen metabolic rates in awake animals and their recently determined numbers of neurons, here I show that, contrary to the expected, the estimated glucose use per neuron is remarkably constant, varying only by 40% across the six species of rodents and primates (including humans). The estimated average glucose use per neuron does not correlate with neuronal density in any structure. This suggests that the energy budget of the whole brain per neuron is fixed across species and brain sizes, such that total glucose use by the brain as a whole, by the cerebral cortex and also by the cerebellum alone are linear functions of the number of neurons in the structures across the species (although the average glucose consumption per neuron is at least 10× higher in the cerebral cortex than in the cerebellum). These results indicate that the apparently remarkable use in humans of 20% of the whole body energy budget by a brain that represents only 2% of body mass is explained simply by its large number of neurons. Because synaptic activity is considered the major determinant of metabolic cost, a conserved energy budget per neuron has several profound implications for synaptic homeostasis and the regulation of firing rates, synaptic plasticity, brain imaging, pathologies, and for brain scaling in evolution

    Human-robot collaboration (HRC) with vision inspection for PCB assembly

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    Flexibility and speed in the development of new industrial machines are essential factors for the success of capital goods industries. When assembling a printed circuit board (PCB), since all the components are surface-mounted devices (SMD), the whole process is automatic. However, in many PCBs, it is necessary to place components that are not SMDs, called pin through-hole components (PTH), having to be inserted manually, which leads to delays in the production line. This work proposes and validates a prototype work cell based on a collaborative robot and vision systems whose objective is to insert these components in a completely autonomous or semi-autonomous way. Different tests were made to validate this work cell, showing the correct implementation and the possibility of replacing the human worker on this PCB assembly task.ERDF - European Regional Development Fund(45070
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