1,820 research outputs found

    Three-frequency resonances in dynamical systems

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    We investigate numerically and experimentally dynamical systems having three interacting frequencies: a discrete mapping (a circle map), an exactly solvable model (a system of coupled ordinary differential equations), and an experimental device (an electronic oscillator). We compare the hierarchies of three-frequency resonances we find in each of these systems. All three show similar qualitative behaviour, suggesting the existence of generic features in the parameter-space organization of three-frequency resonances.Comment: See home page http://lec.ugr.es/~julya

    A method for daily normalization in emotion recognition

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    A ffects carry important information in human communication and decision making, and their use in technology have grown in the past years. Particularly, emotions have a strong e ect on physiology, which can be assessed by biomedical signals. This signals have the advantage that can be recorded continuously, but also can become intrusive. The present work introduce an emotion recognition scheme based only in photoplethysmography, aimed to lower invasiveness. The feature extraction method was developed for a realistic real-time context. Furthermore, a feature normalization procedure was proposed to reduce the daily variability. For classi cation, two well-known models were compared. The proposed algorithms were tested on a public database, which consist of 8 emotions expressed continuously by a single subject along diff erent days. Recognition tasks were performed for several number of emotional categories and groupings. Preliminary results shows a promising performance with up to 3 emotion categories. Moreover, the recognition of arousal and emotional events was improved for larger emotion sets.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    A method for daily normalization in emotion recognition

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    A ffects carry important information in human communication and decision making, and their use in technology have grown in the past years. Particularly, emotions have a strong e ect on physiology, which can be assessed by biomedical signals. This signals have the advantage that can be recorded continuously, but also can become intrusive. The present work introduce an emotion recognition scheme based only in photoplethysmography, aimed to lower invasiveness. The feature extraction method was developed for a realistic real-time context. Furthermore, a feature normalization procedure was proposed to reduce the daily variability. For classi cation, two well-known models were compared. The proposed algorithms were tested on a public database, which consist of 8 emotions expressed continuously by a single subject along diff erent days. Recognition tasks were performed for several number of emotional categories and groupings. Preliminary results shows a promising performance with up to 3 emotion categories. Moreover, the recognition of arousal and emotional events was improved for larger emotion sets.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    A compact energy harvesting system for outdoor wireless sensor nodes based on a low-cost in situ photovoltaic panel characterization-modelling unit

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    This paper presents a low-cost high-efficiency solar energy harvesting system to power outdoor wireless sensor nodes. It is based on a Voltage Open Circuit (VOC) algorithm that estimates the open-circuit voltage by means of a multilayer perceptron neural network model trained using local experimental characterization data, which are acquired through a novel low cost characterization system incorporated into the deployed node. Both units—characterization and modelling—are controlled by the same low-cost microcontroller, providing a complete solution which can be understood as a virtual pilot cell, with identical characteristics to those of the specific small solar cell installed on the sensor node, that besides allows an easy adaptation to changes in the actual environmental conditions, panel aging, etc. Experimental comparison to a classical pilot panel based VOC algorithm show better efficiency under the same tested conditions

    A method for daily normalization in emotion recognition

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    A ffects carry important information in human communication and decision making, and their use in technology have grown in the past years. Particularly, emotions have a strong e ect on physiology, which can be assessed by biomedical signals. This signals have the advantage that can be recorded continuously, but also can become intrusive. The present work introduce an emotion recognition scheme based only in photoplethysmography, aimed to lower invasiveness. The feature extraction method was developed for a realistic real-time context. Furthermore, a feature normalization procedure was proposed to reduce the daily variability. For classi cation, two well-known models were compared. The proposed algorithms were tested on a public database, which consist of 8 emotions expressed continuously by a single subject along diff erent days. Recognition tasks were performed for several number of emotional categories and groupings. Preliminary results shows a promising performance with up to 3 emotion categories. Moreover, the recognition of arousal and emotional events was improved for larger emotion sets.Sociedad Argentina de Informática e Investigación Operativa (SADIO

    Vitamins C and E attenuate plasminogen activator inhibitor-1 (PAI-1) expression in a hypercholesterolemic porcine model of angioplasty

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    BACKGROUND: The plasminogen activator inhibitor-1 (PAI-1), which modulates fibrinolysis and cell migration, may influence proteolysis and neointimal formation in the arterial wall contributing to restenosis after vascular injury. Antioxidants have been proposed as inhibiting multiple proatherogenic events. We explore the effect of vitamins C and E on PAI-1 expression in an experimental model of angioplasty in hypercholesterolemic pigs. METHODS AND RESULTS: A total of 44 Yucatan minipigs were divided into three diet groups: a normal-cholesterol (NC), a high-cholesterol (HC), and a high-cholesterol plus vitamins C+E (HCV) group. Balloon injury was induced in the right internal iliac artery 4 weeks after initiation of either dietary regimen, and plasma and tissue samples were taken at different time periods to measure PAI-1 activity and vascular inhibitor expression. The cholesterol-rich diet induced an increased in vascular PAI-1 expression in the intima, media and adventitia which was markedly reduced in the HCV group. After injury, severe structural changes were observed in NC and HC animals associated with increased systemic PAI-1 activity (P<0.001) and local PAI-1 expression being more intense in HC group. Vitamins C and E significantly reduced plasma PAI-1 activity (P=0.018) and attenuated the inhibitor expression as compared with HC. CONCLUSIONS: This experimental study in a porcine model of hypercholesterolemia demonstrates that vitamins C and E reduce local and systemic PAI-1 induced after angioplasty as well as the hypercholesterolemia-induced vascular PAI-1

    Arthropods in Monk Parakeet nests (Aves: Psittacidae)

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    The objective of this work is to communicate a list of artropodofauna which is in Monk Parakeet (Myiopsitta monachus monachus) nests at several localities in Buenos Aires province. One nest and 43 beds of fresh green material that the Monk Parakeets deposited in the breeding chamber were collected. Arthropods were extracted, identified under binocular microscope, and characterized by their diets. Species were found whitin class Arachnida (Acarina, Pseudoescorpionida and Araneae), mainly predators and hematophagous. Within class Insecta, were found blood-sucking species, predators, detritivores, phytophagous, nectarivorous, and xilophagous, among others. The orders most represented were Diptera (8 families) and Coleoptera (12 families). The rest of the species belonged to the orders Collembola, Psocoptera, Hymenoptera, Phthiraptera, Hemiptera and Lepidoptera.El objetivo de este trabajo es comunicar una lista de la artropodofauna que se encuentra en los nidos de cotorra (Myiopsitta monachus monachus) en distintas localidades de la provincia de Buenos Aires, Argentina. Se colectó un nido y 43 camas de material vegetal fresco que las cotorras depositan en las cámaras de cría. Se extrajeron los artrópodos, que se identificaron bajo lupa binocular y se caracterizaron por su nicho trófico. Se encontraron especies de la clase Arachnida (Acariña, Pseudoescorpionida y Araneae), principalmente depredadoras y hematófagas; mientras que dentro de la clase Insecta se encontraron especies hematófagas, depredadoras, detritívoras, fitófagas, nectarívoras, y xilófagas. Los órdenes más representados fueron Díptera (8 familias) y Coleóptera (12 familias). El resto de las especies pertenecieron a los órdenes Collembola, Psocoptera, Hymenoptera, Phthiraptera, Hemiptera y Lepidoptera.Facultad de Ciencias Naturales y Muse

    Arthropods in Monk Parakeet nests (Aves: Psittacidae)

    Get PDF
    The objective of this work is to communicate a list of artropodofauna which is in Monk Parakeet (Myiopsitta monachus monachus) nests at several localities in Buenos Aires province. One nest and 43 beds of fresh green material that the Monk Parakeets deposited in the breeding chamber were collected. Arthropods were extracted, identified under binocular microscope, and characterized by their diets. Species were found whitin class Arachnida (Acarina, Pseudoescorpionida and Araneae), mainly predators and hematophagous. Within class Insecta, were found blood-sucking species, predators, detritivores, phytophagous, nectarivorous, and xilophagous, among others. The orders most represented were Diptera (8 families) and Coleoptera (12 families). The rest of the species belonged to the orders Collembola, Psocoptera, Hymenoptera, Phthiraptera, Hemiptera and Lepidoptera.El objetivo de este trabajo es comunicar una lista de la artropodofauna que se encuentra en los nidos de cotorra (Myiopsitta monachus monachus) en distintas localidades de la provincia de Buenos Aires, Argentina. Se colectó un nido y 43 camas de material vegetal fresco que las cotorras depositan en las cámaras de cría. Se extrajeron los artrópodos, que se identificaron bajo lupa binocular y se caracterizaron por su nicho trófico. Se encontraron especies de la clase Arachnida (Acariña, Pseudoescorpionida y Araneae), principalmente depredadoras y hematófagas; mientras que dentro de la clase Insecta se encontraron especies hematófagas, depredadoras, detritívoras, fitófagas, nectarívoras, y xilófagas. Los órdenes más representados fueron Díptera (8 familias) y Coleóptera (12 familias). El resto de las especies pertenecieron a los órdenes Collembola, Psocoptera, Hymenoptera, Phthiraptera, Hemiptera y Lepidoptera.Facultad de Ciencias Naturales y Muse

    The role of selenium mineral trace element in exercise: antioxidant defense system, muscle performance, hormone response, and athletic performance. A systematic review

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    Exercise overproduces oxygen reactive species (ROS) and eventually exceeds the body’s antioxidant capacity to neutralize them. The ROS produce damaging effects on the cell membrane and contribute to skeletal muscle damage. Selenium (Se), a natural mineral trace element, is an essential component of selenoproteins that plays an important role in antioxidant defense. The activity of the enzyme glutathione peroxidase (GPx), a highly-efficient antioxidant enzyme, is closely dependent on the presence of Se. These properties of Se may be potentially applicable to improve athletic performance and training recovery. We systematically searched for published studies to evaluate the effectiveness of Se supplementation on antioxidant defense system, muscle performance, hormone response, and athletic performance among physically active individuals. We used the Preferred Reporting Elements for Systematic Reviews and Meta-Analysis (PRISMA) guidelines and searched in SCOPUS, Web of Science (WOS), and PubMed databases to identify published studies until March 2020. The systematic review incorporated original studies with randomized controlled crossover or parallel design in which intake of Se administered once a day was compared with the same placebo conditions. No exclusions were applied for the type of physical exercise performed, the sex, nor the age of the participants. Among 150 articles identified in the search, 6 met the criteria and were included in the systematic review. The methodological quality of the studies was evaluated using the McMaster Critical Review Form. Oral Se supplementation with 180 µg/day or 240 µg/day (selenomethionine) and 200 µg/day (Sodium Selenite), significantly decreased lipid hydroperoxide levels and increased GPx in plasma, erythrocyte, and muscle. No significant effects were observed on athletic performance, testosterone hormone levels, creatine kinase activity, and exercise training-induced adaptations on oxidative enzyme activities or on muscle fiber type myosin heavy chain expression. In addition, Se supplementation showed to have a dampening effect on the mitochondria changes in chronic and acute exercise. In summary, the use of Se supplementation has no benefits on aerobic or anaerobic athletic performance but it may prevent Se deficiencies among athletes with high-intensity and high-volume training. Optimal Se plasma levels may be important to minimize chronic exercise-induced oxidative effects and modulate the exercise effect on mitochondrial changes

    Three-frequency resonances in dynamical systems

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    We investigate numerically and experimentally dynamical systems having three interacting frequencies: a discrete mapping (a circle map), an exactly solvable model (a system of coupled ordinary differential equations), and an experimental device (an electronic oscillator). We compare the hierarchies of three-frequency resonances we find in each of these systems. All three show similar qualitative behaviour, suggesting the existence of generic features in the parameter-space organization of three-frequency resonances.Facultad de IngenieríaInstituto de Investigaciones en Electrónica, Control y Procesamiento de Señale
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