300 research outputs found

    Non-monotonic entanglement of physical EM field states in non-inertial frames

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    We develop a general technique to analyse the quantum effects of acceleration on realistic spatially-localised electromagnetic field states entangled in the polarization degree of freedom. We show that for this setting, quantum entanglement may build up as the acceleration increases, providing a clear signature of the quantum effects of relativistic acceleration.Comment: 5 pages, 3 figure

    Intervención en el Castillo de Biar. Consolidación de una ruina como alternativa posibilista en la defensa del patrimonio

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    [EN] Consolidation of ruin and didactic recovery of the castle's profile dominating the landscape. Almohad fortress that should have been recorded at the beginning of the powerful existing tower, surrounded by a protective wall with adarve, all on steep rocks. The fortress is transformed over time, being in service as a defense between Muslim Spain and Christian Spain in the twelfth and thirteenth centuries, to later, be a point of friction between the Kingdoms of Castilla and Aragón, remaining active until the mid-sixteenth century, with an intervention in the nineteenth century during the Carlist wars. Is located on the top of a hill at 745 m altitude, next to the town. The orography marks a deep slope to the northeast, more than 100 m high, while to the west, falling towards the population, the slope is smoother. Because of its situation, the castle has a very important visual impact, so landscape considerations acquire a special meaning. The intervention is partial on the second walled enclosure and in total ruin, proposing an eloquent restoration that allows to approach its complex history and the construction techniques used, within a strong economy of means in the project and subsequent maintenance. We can restore the image of the courtyard, its spatiality and know the remains of existing buildings. Both, the remnants emptying of crashes, and the restoration of the traces of the internal walls, the various heights of the walls and their guard steps, allow us to understand the whole along the time. The undoubted visual and landscape interest of Biar Castle is a relevant aspect of the intervention.Del Rey, M.; Gallud Martínez, A. (2020). Intervención en el Castillo de Biar. Consolidación de una ruina como alternativa posibilista en la defensa del patrimonio. Editorial Universitat Politècnica de València. 1367-1374. https://doi.org/10.4995/FORTMED2020.2020.11352OCS1367137

    Effects of Copenhagen Adduction Exercise on the Architectural Characteristics of Adductors in U-17 Male Soccer Players : A Randomized Controlled Trial

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    [Abstract] Groin injuries are one of the most prevalent in male soccer players, especially due to the hip adductor muscles’ weakness which is considered as a risk factor in these injuries. The Copenhagen adduction (CA) exercise has been demonstrated to increase the strength of adductor muscles, but its effects on the architectural characteristics of adductor muscles have not been studied yet. This study aimed to analyze the effects of the CA exercise on the muscle thickness of the adductors. Twelve male U-17 soccer players were randomized into two groups: the control group with no intervention and the experimental group with an intervention based on an eight-week training with CA exercise. The muscle thickness of adductors was measured before and after the intervention using ultrasound imaging. A significant increase in muscle thickness was found in both control (p = 0.002) and experimental group (p < 0.001), but the experimental group did not show additional effects in comparison with the control group. In conclusion, an 8-week CA exercise intervention does not increase the muscle thickness of adductors in U-17 soccer players more than their regular training

    Restoration enhances wetland biodiversity and ecosystem service supply, but results are context-dependent: a meta-analysis

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    Wetlands are valuable ecosystems because they harbor a huge biodiversity and provide key services to societies. When natural or human factors degrade wetlands, ecological restoration is often carried out to recover biodiversity and ecosystem services (ES). Although such restorations are routinely performed, we lack systematic, evidence-based assessments of their effectiveness on the recovery of biodiversity and ES. Here we performed a meta-analysis of 70 experimental studies in order to assess the effectiveness of ecological restoration and identify what factors affect it. We compared selected ecosystem performance variables between degraded and restored wetlands and between restored and natural wetlands using response ratios and random-effects categorical modeling. We assessed how context factors such as ecosystem type, main agent of degradation, restoration action, experimental design, and restoration age influenced post-restoration biodiversity and ES. Biodiversity showed excellent recovery, though the precise recovery depended strongly on the type of organisms involved. Restored wetlands showed 36% higher levels of provisioning, regulating and supporting ES than did degraded wetlands. In fact, wetlands showed levels of provisioning and cultural ES similar to those of natural wetlands; however, their levels of supporting and regulating ES were, respectively, 16% and 22% lower than in natural wetlands. Recovery of biodiversity and of ES were positively correlated, indicating a win-win restoration outcome. The extent to which restoration increased biodiversity and ES in degraded wetlands depended primarily on the main agent of degradation, restoration actions, experimental design, and ecosystem type. In contrast, the choice of specific restoration actions alone explained most differences between restored and natural wetlands. These results highlight the importance of comprehensive, multi-factorial assessment to determine the ecological status of degraded, restored and natural wetlands and thereby evaluate the effectiveness of ecological restorations. Future research on wetland restoration should also seek to identify which restoration actions work best for specific habitats

    Effects of grass clearing and soil tilling on establishment of planted tree seedlings in tropical riparian pastures

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    Anthropogenic disturbances frequently exceed resilience of riparian forests. In small-scale restoration projects revegetation is a common technique, but its success depends on the plant species used and some environmental filters. We investigated whether grass competition and soil compaction together with seasonal drought and flooding limit the establishment of seven tree species experimentally planted in abandoned riparian pastures in Southern Mexico. We tested the effects of grass clearing and soil tilling and analyzed seasonal variation of vertical distance to water level, and changes in tree performance, microclimate, and vegetation biomass after planting. Seedling survival was low (19 ± 3 %), ranging between 3 (Brosimum alicastrum, Moraceae) and 38 % (Pachira aquatica, Bombacaceae). Survival was negatively correlated to vertical distance to water level, highlighting the importance of the short but severe dry season that may occur in the humid tropics, which reduced survival by >60 %. Flooding events also produced high seedling mortality (80 % after the two first events). Clearing but not tilling enhanced seedling survival. Clearing also significantly increased seedling growth of some species, suggesting competition release. Tilling did not have any consistent effect on growth, but it appears to counteract the positive effects of clearing. Both pre-existing and planted trees ameliorated microclimate to produce better conditions for establishment of new trees following natural regeneration. We conclude that clearing can enhance seedling establishment in riparian abandoned tropical pastures, but other revegetation treatments intended to reduce soil drying and uprooting by flooding during early establishment should be evaluated to improve the cost-benefit of restoring riparian forest.Ministerio de Ciencia y EducaciónComunidad de MadridUniversidad Nacional Autónoma de Méxic

    No sport for old players. A longitudinal study of aging effects on match performance in elite soccer

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    Financiado para publicación en acceso aberto: Universidade de Vigo/CISUGObjectives: This study aimed to examine the effects of age on match-related physical and technical–tactical performance in elite soccer players using a longitudinal design. Methods: Data were collected from 154 players who competed in the Spanish first division (LaLiga) between the 2012–13 and 2019–20 seasons. A total of 14,092 individual match observations were analyzed using a computerized tracking system (TRACAB, Chyronhego, New York, NY). The players were classified into five positional roles: central defenders (n = 37); external defenders (n = 44); central midfielders (n = 34); external midfielders (n = 22); and forwards (n=17). Results: The main results showed that (a) soccer players decreased by an average of 0.56% their total distance covered for each year that they got older. Similarly, the number of high-intensity efforts and distance covered at high-intensity running decreased by 1.80% and 1.42% per year, respectively; (b) players significantly increased their pass accuracy by an average of 0.25% each year that they got older; (c) the detrimental effect of age on total distance and high-intensity runningwas greater for external defenders, external midfielders, and forwards; and (d) the positive effect of age on pass accuracy was greater for central defenders and central midfielders. Conclusions: Elite soccer players with long-term careers were unable to maintain their match-related physical performance as they got older. However, players can annually improve their technical–tactical skills with increasing age as a possible compensation mechanism against physical performance declines related to aging

    Self-Triggered Formation Control of Nonholonomic Robots

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    In this paper, we report the design of an aperiodic remote formation controller applied to nonholonomic robots tracking nonlinear, trajectories using an external positioning sensor network. Our main objective is to reduce wireless communication with external sensors and robots while guaranteeing formation stability. Unlike most previous work in the field of aperiodic control, we design a self-triggered controller that only updates the control signal according to the variation of a Lyapunov function, without taking the measurement error into account. The controller is responsible for scheduling measurement requests to the sensor network and for computing and sending control signals to the robots. We design two triggering mechanisms: centralized, taking into account the formation state and decentralized, considering the individual state of each unit. We present a statistical analysis of simulation results, showing that our control solution significantly reduces the need for communication in comparison with periodic implementations, while preserving the desired tracking performance. To validate the proposal, we also perform experimental tests with robots remotely controlled by a mini PC through an IEEE 802.11g wireless network, in which robots pose is detected by a set of camera sensors connected to the same wireless network

    Federated Learning for Malware Detection in IoT Devices

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    The Internet of Things (IoT) is penetrating many facets of our daily life with the proliferation of intelligent services and applications empowered by artificial intelligence (AI). Traditionally, AI techniques require centralized data collection and processing that may not be feasible in realistic application scenarios due to the high scalability of modern IoT networks and growing data privacy concerns. Federated Learning (FL) has emerged as a distributed collaborative AI approach that can enable many intelligent IoT applications, by allowing for AI training at distributed IoT devices without the need for data sharing. In this article, we provide a comprehensive survey of the emerging applications of FL in IoT networks, beginning from an introduction to the recent advances in FL and IoT to a discussion of their integration. Particularly, we explore and analyze the potential of FL for enabling a wide range of IoT services, including IoT data sharing, data offloading and caching, attack detection, localization, mobile crowdsensing, and IoT privacy and security. We then provide an extensive survey of the use of FL in various key IoT applications such as smart healthcare, smart transportation, Unmanned Aerial Vehicles (UAVs), smart cities, and smart industry. The important lessons learned from this review of the FL-IoT services and applications are also highlighted. We complete this survey by highlighting the current challenges and possible directions for future research in this booming area

    Federated Learning for Malware Detection in IoT Devices

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    The Internet of Things (IoT) is penetrating many facets of our daily life with the proliferation of intelligent services and applications empowered by artificial intelligence (AI). Traditionally, AI techniques require centralized data collection and processing that may not be feasible in realistic application scenarios due to the high scalability of modern IoT networks and growing data privacy concerns. Federated Learning (FL) has emerged as a distributed collaborative AI approach that can enable many intelligent IoT applications, by allowing for AI training at distributed IoT devices without the need for data sharing. In this article, we provide a comprehensive survey of the emerging applications of FL in IoT networks, beginning from an introduction to the recent advances in FL and IoT to a discussion of their integration. Particularly, we explore and analyze the potential of FL for enabling a wide range of IoT services, including IoT data sharing, data offloading and caching, attack detection, localization, mobile crowdsensing, and IoT privacy and security. We then provide an extensive survey of the use of FL in various key IoT applications such as smart healthcare, smart transportation, Unmanned Aerial Vehicles (UAVs), smart cities, and smart industry. The important lessons learned from this review of the FL-IoT services and applications are also highlighted. We complete this survey by highlighting the current challenges and possible directions for future research in this booming area
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