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This paper introduces a quadrotor trajectory tracking controller comprising a steady-state optimal position controller with a normed input saturation and modular integrative action coupled with a backstepping attitude controller. First, the translational and rotational dynamical models are designed in the body-fixed frame to avoid external rotations and are partitioned into an underactuated position system and a quaternion-based attitude system. Secondly, a controller is designed separately for each subsystem, namely, (i) the position controller synthesis is derived from the Maximum Principle, Lyapunov, and linear quadratic regulator (LQR) theory, ensuring the global exponential stability and steady-state optimality of the controller within the linear region, and global asymptotic stability is guaranteed for the saturation region when coupled with any local exponential stable attitude controller, and (ii) the attitude system, with the quaternion angles and the angular velocity as the controlled variables, is designed in the error space through the backstepping technique, which renders the overall system, position, and attitude, with desirable closed-loop properties that are almost global. The overall stability of the system is achieved through the propagation of the position interconnection term to the attitude system. To enhance the robustness of the tracking system, integrative action is devised for both position and attitude, with emphasis on the modular approach for the integrative action on the position controller. The proposed method is experimentally validated on board an off-the-shelf quadrotor to assess the resulting performance.

Fifth-generation (5G) cellular communication systems have embraced massive multiple-input-multiple-output (MIMO) in the low- and mid-band frequencies. In a multiband system, the base station can serve different users in each band, while the user equipment can operate only in a single band simultaneously. This paper considers a massive MIMO system where channels are dynamically allocated in different frequency bands. We treat multiband massive MIMO as a scheduling and resource allocation problem and propose deep reinforcement learning (DRL) agents to perform user scheduling. The DRL agents use buffer and channel information to compose their observation space, and the agent’s reward function maximizes the transmitted throughput and minimizes the packet loss rate. We compare the proposed DRL algorithms with traditional baselines, such as maximum throughput and proportional fairness. The results show that the DRL models outperformed baselines obtaining a 20% higher network sum rate and an 84% smaller packet loss rate. Moreover, we compare different DRL algorithms focusing on training time to assess the online implementation of the DRL agents, showing that the best agent needs about 50K training steps to converge.

During development, cells must quickly switch from one cell state to the next to execute precise and timely differentiation. One method to ensure fast transitions in cell states is by controlling gene expression at the post-transcriptional level through action of RNA-binding proteins on mRNAs. The ability to accurately identify the RNA targets of RNA-binding proteins at specific stages is key to understanding the functional role of RNA-binding proteins during development. Here we describe an adapted formaldehyde RNA immunoprecipitation (fRIP) protocol to identify the in vivo RNA targets of a cytoplasmic RNA-binding protein, YTHDC2, from testis, during the first wave of spermatogenesis, at the stage when germ cells are shutting off the proliferative program and initiating terminal differentiation (Bailey et al., 2017). This protocol enables quick and efficient identification of endogenous RNAs bound to an RNA-binding protein, and facilitates the monitoring of stage-specific changes during development.

Abstract Biochar (BCH) is a solid product, rich in carbon, obtained by heating biomass under controlled conditions of oxygenation, in a process known as pyrolysis. Its benefits are associated with improvements to the physical, chemical and biological properties of soil. Furthermore, BCH can affect the growth of phytopathogenic microorganisms. Despite research advances in this area, there is still a lack of information on the effect of BCH concentration on different soilborne microorganisms. This work evaluated the direct effect of sewage sludge biochar (SSB) on the in vitro growth of different soilborne fungi. Eight phytopathogens [Fusarium oxysporum, F. oxysporum f. sp. lycopersici (CEN 1456), Macrophomina phaseolina (429), Sclerotinia sclerotiorum, S. sclerotiorum (CEN 1147), Sclerotium rolfsii (CEN 216), Sclerotium cepivorum (CEN 1357), Rhizoctonia solani] were evaluated. Additionally, a biological control agent [Trichoderma afroharzianum (T-22)] was also studied. Microorganisms were subjected to growth in PDA (Potato-Dextrose-Agar) culture medium enriched with SSB. Biochars, produced at 300 and 500 ºC, were applied at different doses: 0.0 (control), 0.2, 0.4, 0.6, 0.8 and 1.0 (g of SSB/100 ml of PDA). Biochars showed inhibitory effects on the mycelial growth of the different fungi evaluated. It was observed that there is a certain specificity of biochar concentration that must be evaluated for the control of phytopathogens. In most cases, the 0.4 and 0.6% concentrations had a greater inhibitory effect on phytopathogens and did not affect the biological control agent. Therefore, SSB proved to be a promising product for the control of different soilborne phytopathogens.

The fifth-generation (5G) cellular networks incorporate a large variety of technologies in order to address very distinct use cases. Assessing these technologies and investigating future alternatives is complicated when one relies only on simulators. 5G testbeds are an important alternative to simulators and many have been recently described, emphasizing aspects such as cloud functionalities, management and orchestration. This work presents a 5G mobile network testbed with a virtualized and orchestrated structure using containers, which focuses on integration to artificial intelligence (AI) applications. The presented testbed uses open-source technologies to deploy and orchestrate the virtual network functions (VNFs) to flexibly create various mobile network scenarios, with distinct fronthaul and backhaul topologies. Distinctive features of the testbed are its relatively low cost and the support to using AI for optimizing the network performance. The paper explains how to deploy the testbed structure and reproduce the presented results with the provided code. AI-based radio access network (RAN) slicing and VNF placement are used as examples of the testbed capabilities.

Pleurotussp. es un género de basidiomicetos ampliamente distribuido a nivel mundial, con especies que revisten importancia, no solo desde el punto de vista comercial por su valor nutricional, sino también por sus propiedades medicinales. Sin embargo, aún son insuficientes los estudios micoquímicos y se desconoce su relación con las propiedades antioxidantes de bioproductos obtenidos de estas setas durante diferentes estados de crecimiento. En el presente trabajo, se determinó el contenido de proteínas, carbohidratos, azúcares reductores, fenoles totales y flavonoides, así como la actividad antioxidante in vitro(ensayos de captación de radicales DPPH y estimación del poder reductor) de extractos acuosos de Pleurotus ostreatusen dos estados de crecimiento (primordios y cuerpos fructíferos maduros) durante la fermentación sólida. El contenido de proteínas, azúcares reductores y flavonoides fue superior en el extracto acuoso de cuerpos fructíferos maduros, mientras que los carbohidratos y fenoles totales fueron mayores en el extracto de primordios. Los valores de EC50en los ensayos de DPPH y los de poder reductor fueron de 1,72 mg/mL y 3,27 mg/mL para el extracto de primordios y de 0,44 mg/mL y 0,48 mg/mL para el de cuerpos fructíferos maduros, respectivamente. Los resultados sugieren que las propiedades antioxidantes de extractos acuosos de Pleurotus ostreatus(primordios y cuerpos fructíferos maduros) reflejan las variaciones en la concentración de moléculas bioactivas, teniendo en cuenta las particularidades fisiológicas de las fases de crecimiento. Ello podría resultar de utilidad para el diseño de protocolos de obtención de bioproductos de Pleurotus ostreatuscon aplicaciones potenciales como antioxidantes en las industrias alimentaria y farmacéutica.

The uncertainty analysis of attitude estimates enables the comparison between different methods, and, thus, it is important for practical applications. This work studies the uncertainty for the attitude determination of a three-vehicle constrained formation. Moreover, the existing solution is improved by including the uncertainty results in a weighted orthogonal Procrustes problem. In the formation considered herein, the vehicles measure inertial references and relative line-of-sight vectors. Nonetheless, the line of sight between two elements of the formation is restricted. The uncertainty analysis uses perturbation theory and, consequently, considers a small first-order perturbation in the measurements. The covariance matrices are obtained for all relative and inertial attitude candidates from the linearization of the solution using a first-order Taylor expansion. Then, the uncertainty is completed by considering the covariance for the weighted orthogonal Procrustes problem, from the literature, and the definition of covariance for the remaining attitudes. The uncertainty characterization is valid for configurations with a unique solution. Finally, the theoretical results are validated by applying Monte Carlo simulations, which show that the predicted errors are statistically consistent with the numerical implementation of the solution with noise. Furthermore, the theoretical uncertainty predicts the accuracy changes near special configurations where there is loss of information.

The existence of multiple solutions to an attitude determination problem impacts the design of estimation schemes, potentially increasing the errors by a significant value. It is therefore essential to identify such cases in any attitude problem. In this paper, the cases where multiple attitudes satisfy all constraints of a three-vehicle heterogeneous formation are identified. In the formation considered herein, the vehicles measure inertial references and relative line-of-sight vectors. Nonetheless, the line of sight between two elements of the formation is restricted, and these elements are denoted as deputies. The attitude determination problem is characterized relative to the number of solutions associated with each configuration of the formation. There are degenerate and ambiguous configurations that result in infinite or exactly two solutions, respectively. Otherwise, the problem has a unique solution. The degenerate configurations require some collinearity between independent measurements, whereas the ambiguous configurations result from symmetries in the formation measurements. The conditions which define all such configurations are determined in this work. Furthermore, the ambiguous subset of configurations is geometrically interpreted resorting to the planes defined by specific measurements. This subset is also shown to be a zero-measure subset of all possible configurations. Finally, a maneuver is simulated to illustrate and validate the conclusions. As a result of this analysis, it is concluded that, in general, the problem has one attitude solution. Nonetheless, there are configurations with two or infinite solutions, which are identified in this work.

In this short communication, an algorithm for efficiently solving a sparse matrix equation, which arises frequently in the field of distributed control and estimation theory, is proposed. The efficient algorithm stems from the fact that the sparse equation at hand can be reduced to a system of linear equations. The proposed algorithm is shown to require significantly fewer floating point operations than the state-of-the-art solution. The proposed solution is applied to a real-life example, which models a wide range of industrial processes. The experimental results show that the solution put forward allows for a significant increase in efficiency in relation to the state-of-the-art solution. The significant increase in efficiency of the presented algorithm allows for a valuable widening of the applications of distributed estimation and control.

This paper presents the steps for developing a low-cost POrtableNavigation Tool for Underwater Scenarios (PONTUS) to be used as a localization device for subsea targets. PONTUS consists of an integrated ultra-short baseline acoustic positioning system aided by an inertial navigation system. Built on a practical design, it can be mounted on an underwater robotic vehicle or be operated by a scuba diver. It also features a graphical user interface that provides information on the tracking of the designated target, in addition to some details on the physical properties inside PONTUS. A full disclosure of the architecture of the tool is first presented, followed by thorough technical descriptions of the hardware components ensemble and the software development process. A series of experiments was carried out to validate the developed prototype, and the results are presented herein, which allow assessing its overall performance.

Resumo Objetivo: Caracterizar a população de diabéticos referenciados à consulta de Oftalmologia do Centro Hospitalar do Porto (CHP) através do programa de rastreio da ARS Norte, avaliar este tipo de método de rastreio e perceber o impacto do mesmo na dinâmica de um Serviço de Oftalmologia. Métodos: Avaliação retrospectiva dos processos clínicos dos utentes diabéticos referenciados à consulta de Rastreio de Retinopatia Diabética (RD) do CHP através do programa de rastreio da ARS Norte, entre Janeiro de 2012 e Dezembro de 2016. As variáveis analisadas foram: dados demográficos, duração e tipo de Diabetes Mellitus (DM), seguimento prévio em consulta de oftalmologia, tipo de retinopatia diabética e orientação subsequente. Resultados: Dos 613 doentes diabéticos observados nesta consulta 2.6% tinham DM tipo 1 e 97.4% tinham DM tipo 2, com duração média da doença de 15.8 anos e 6.6% não apresentava lesões de RD em qualquer um dos olhos; lesões de RD não proliferativa estavam presentes em 90.7% dos doentes, sendo bilaterais em 83.7% dos casos e 2.7% apresentava lesões de RD proliferativa em ambos os olhos. No momento da consulta, 31.9% apresentava maculopatia, em pelo menos um dos olhos. 51,1% dos doentes tinha no momento da consulta indicação para tratamento; 15.2% integraram a consulta de diabetes ocular do CHP por necessidade de vigilância e 33.7% tiveram alta para reintegrarem este programa de rastreio. Conclusões: O programa de rastreio de RD apresenta-se como uma ferramenta útil e necessária no diagnóstico precoce e tratamento atempado das lesões de RD.