Hyperparameter Control Using Fuzzy Logic: Evolving Policies for Adaptive Fuzzy Particle Swarm Optimization Algorithm.

Heuristic optimization methods such as Particle Swarm Optimization depend on their parameters to achieve optimal performance on a given class of problems. Some modifications of heuristic algorithms aim at adapting those parameters during the optimization process. We present a novel approach to design such adaptation strategies using continuous fuzzy feedback control. Fuzzy feedback provides a simple interface where probes are sampled in the optimization process and parameters are fed back to the optimizer. The probes are turned into parameters by a fuzzy process optimized beforehand to maximize performance on a training benchmark. Utilizing this framework, we systematically established 127 different Fuzzy Particle Swarm Optimization algorithms featuring a maximum of 7 parameters under fuzzy control. These newly devised algorithms exhibit superior performance compared to both traditional PSO and some of its best parameter control variants. The performance is reported in the single-objective bound-constrained numerical optimization competition of CEC 2020. Additionally, two specific controls, highlighted for their efficacy and dependability, demonstrated commendable performance in real-world scenarios from CEC 2011.

Genetic-algorithm-aided ultra-broadband perfect absorbers using plasmonic metamaterials.

Complete absorption of electromagnetic waves is paramount in today's applications, ranging from photovoltaics to cross-talk prevention into sensitive devices. In this context, we use a genetic algorithm (GA) strategy to optimize absorption properties of periodic arrays of truncated square-based pyramids made of alternating stacks of metal/dielectric layers. We target ultra-broadband quasi-perfect absorption of normally incident electromagnetic radiations in the visible and near-infrared ranges (wavelength comprised between 420 and 1600 nm). We compare the results one can obtain by considering one, two or three stacks of either Ni, Ti, Al, Cr, Ag, Cu, Au or W for the metal, and poly(methyl methacrylate) (PMMA) for the dielectric. More than 1017 configurations of geometrical parameters are explored and reduced to a few optimal ones. This extensive study shows that Ni/PMMA, Ti/PMMA, Cr/PMMA and W/PMMA provide high-quality solutions with an integrated absorptance higher than 99% over the considered wavelength range, when considering realistic implementation of these ultra-broadband perfect electromagnetic absorbers. Robustness of optimal solutions with respect to geometrical parameters is investigated and local absorption maps are provided. Moreover, we confirm that these optimal solutions maintain quasi-perfect broadband absorption properties over a broad angular range when changing the inclination of the incident radiation. The study also reveals that noble metals (Au, Ag, Cu) do not provide the highest performance for the present application.

Efeitos de oito semanas de treinamento com estimulação elétrica neuromuscular nas razões de ativação muscular / torque de idosas com osteoartrite / Effects of eight weeks of neuromuscular electrical stimulation training on muscle activation / torque ratios in elderly women with osteoarthritis

Introdução: O envelhecimento causa prejuízos no sistema musculoesquelético que podem ocasionar a osteoartrite, provocando degeneração da cartilagem articular e, consequentemente, perdas funcionais a idosos acometidos. Por outro lado, a estimulação elétrica neuromuscular é utilizada como treinamento para fortalecimento muscular.Objetivo: Investigar o efeito de oito semanas de treinamento com neuromuscular electrical stimulation (NMES) nas razões de ativação root mean square (RMS) / torque dos músculos extensores do joelho em idosas com osteoartrite. Metodologia: Vinte e quatro idosas foram divididas em dois grupos: grupo saudável (SAU; n=12) e grupo osteoartrite (OA; n=12). O grupo OA foi submetido a oito semanas de treinamento com NMES e tempo de aplicação variando de 18 a 32 minutos e frequência semanal de três vezes.Resultados: No grupo OA, ocorreu um aumento dos valores RMS pós-treinamento comparado com o pré-treinamento (p<0,05). O grupo SAU permaneceu igual ao grupo OA pós-treinamento (p>0,05). O torque do quadríceps aumentou pós-treinamento no grupo OA no ângulo de 90° de flexão do joelho, contudo, o grupo SAU apresentou maior produção de torque em todos os ângulos avaliados (p<0,05). No grupo OA, houve aumento das razões RMS / torque após o treinamento para os ângulos de 60º, 75º e 90º de flexão do joelho (p<0,05), mas não diferindo do grupo SAU (p>0,05).Conclusão: Oito semanas de treinamento com NMES aumentaram a ativação muscular e torque dos músculos extensores do joelho no grupo osteoartrite, mas não foram capazes de gerar adaptações suficientes para igualar os mesmos ao grupo saudável.

Introduction: Aging affects the musculoskeletal system, which can lead to osteoarthritis, causing degeneration of the articular cartilage and consequently resulting in functional impairment among elderly patients. However, neuromuscular electrical stimulation (NMES) training can be used as a mode of muscle strengthening.Objective: To investigate the effects of eight weeks of NMES training of the knee extensors on the RMS/torque ratio of elderly persons with osteoarthritis.Methods: Twenty-four elderly women were assigned into two groups: a healthy group (HE; n=12) and an osteoarthritis group (OA; n=12). The OA group was submitted to eight weeks of NMES training.Results: In the OA group, the RMS values increased from the pre-training to the post-training periods (p<0.05). The HE group did not differ from the OA group in the post-training period (p>0.05). Quadriceps torque was higher in the OA group in the post-training period at 90º of knee flexion (p<0.05) but the torque in the HE group remained higher than in the OA group for all the angles evaluated (p<0.05). The RMS/torque ratios increased in the post-training period at 60º, 75º and 90º of knee flexion (p<0.05), but did not differ between the HE and OA groups (p>0.05).Conclusion: Eight weeks of NMES training resulted in a significant increase in the RMS and torque values of the quadriceps, but these neural adaptations were not sufficient to improve the osteoarthritis group to levels similar to the healthy group.

A fair comparison between ultrathin crystalline-silicon solar cells with either periodic or correlated disorder inverted pyramid textures.

Fabrication of competitive solar cells based on nano-textured ultrathin silicon technology is challenging nowadays. Attention is paid to the optimization of this type of texture, with a lot of simulation and experimental results published in the last few years. While previous studies discussed mainly the local features of the surface texture, we highlight here the importance of their filling fraction. In this work, we focus on a fair comparison between a technologically realizable correlated disorder pattern of inverted nano-pyramids on an ultrathin crystalline-silicon layer, and its periodically patterned counterpart. A fair comparison is made possible by defining an equivalent periodic structure for each hole filling fraction. Moreover, in order to be as realistic as possible, we consider patterns that could be fabricated by standard patterning techniques: hole-mask colloidal lithography, nanoimprint lithography and wet chemical etching. Based on numerical simulations, we show that inverted nano-pyramid patterns with correlated disorder provide typically greater efficiency than their periodic counterparts. However, the hole filling fraction of the etched pattern plays a crucial role and may limit the benefits of the correlated disorder due to experimental restrictions on pattern fabrication.

Evaluation of the lumbar multifidus in rowers during spinal stabilization exercise / Avaliação dos multífidos lombares em atletas do remo durante exercício de estabilização vertebral / Evaluación del multifidus lumbar en los atletas de remo durante el ejercicio en la estabilización de la columna vertebral

Lumbar stabilization is important in high performance rowing due to the high incidence of low back pain. The purpose of this study was to evaluate the lumbar stabilizers muscles performance during an exercise of spinal segmental stabilization and in lumbar multifidus muscle thickness in rowing athletes trained and untrained for this exercise. Nine rowers trained with lumbar stabilization (TLS) and eight rowers without training (CON) participated in the study. Lumbar stabilization performance and multifidus muscle thickness were measured during a maximal voluntary isometric contraction. Lumbar stabilization performance was higher (p=0.015) in the TLS (mean 18.38 ± 8.00 mmHg) compared to the CON (9.31 ± 4.91 mmHg) group. Muscle thickness variation was higher (p=0.023) in the TLS (6.92% ± 3.98) compared to the CON (2.81% ± 1.40) group. Lumbar stabilization training is an efficient clinical tool to strengthen lumbar muscles and may help to prevent low back pain in rowers.

A estabilização lombar é fundamental em esportes de alto rendimento como o remo, devido a elevada incidência de lombalgia. O objetivo do presente estudo foi avaliar o desempenho dos músculos estabilizadores lombares e a espessura do músculo multífido lombar durante um exercício de estabilização segmentar vertebral em remadores. Nove remadores treinados com exercícios de estabilização lombar (TLS) e oito remadores destreinados (CON) foram avaliados. O desempenho dos músculos estabilizadores lombares e a espessura dos músculos multífidos foram mensurados durante uma contração voluntária isométrica máxima. O desempenho foi maior (p=0,015) no grupo TLS (18,38±8,00 mmHg) quando comparado ao grupo CON (9,31±4,91 mmHg). A variação da espessura muscular foi maior (p=0,023) no grupo TLS (6,92%±3.98) quando comparado com o grupo CON (2,81%±1,40). Treinamento de estabilização lombar é uma ferramenta clínica eficiente para fortalecimento da musculatura lombar e pode auxiliar na prevenção de lombalgia em remadores.

La estabilización lumbar es fundamental en la práctica de deportes como el remo de alto rendimiento, donde la lumbalgia aparece con frecuencia. El objetivo de este estudio fue evaluar el rendimiento de los músculos estabilizadores lumbares, así como el espesor del músculo multifido lumbar, durante un ejercicio de estabilización espinal segmentaria lumbar (una contracción isométrica voluntaria máxima) en atletas de remo. Fueron evaluados nueve remadores sometidos a entrenamiento con ejercicios de estabilización lumbar (TLS) y ocho sin este adiestramiento (CON). El rendimiento fue mayor (p=0,015) en el grupo TLS (18,38±8,00 mmHg) e comparación con el grupo CON (9,31±4,91 mmHg). Variación del espesor muscular fue mayor (p=0,023) en el grupo TLS (6,92%±3,98) en comparación con el grupo CON (2,81%±1,40). El entrenamiento lumbar es una herramienta clínica eficiente para el fortalecimiento de la musculatura lumbar e puede auxiliar en la prevención de lumbalgias en remadores.

Multi-objective genetic algorithm for the optimization of a flat-plate solar thermal collector.

We present a multi-objective genetic algorithm we developed for the optimization of a flat-plate solar thermal collector. This collector consists of a waffle-shaped Al substrate with NiCrOx cermet and SnO(2) anti-reflection conformal coatings. Optimal geometrical parameters are determined in order to (i) maximize the solar absorptance α and (ii) minimize the thermal emittance ε. The multi-objective genetic algorithm eventually provides a whole set of Pareto-optimal solutions for the optimization of α and ε, which turn out to be competitive with record values found in the literature. In particular, a solution that enables α = 97.8% and ε = 4.8% was found.

Neuromuscular electrical stimulation (NMES) reduces structural and functional losses of quadriceps muscle and improves health status in patients with knee osteoarthritis.

Knee osteoarthritis (OA) is associated with quadriceps atrophy and weakness, so muscle strengthening is an important point in the rehabilitation process. Since pain and joint stiffness make it often difficult to use conventional strength exercises, neuromuscular electrical stimulation (NMES) may be an alternative approach for these patients. This study was aimed at (1) identifying the associations of knee OA with quadriceps muscle architecture and strength, and (2) quantifying the effects of a NMES training program on these parameters. In phase 1, 20 women with knee OA were compared with 10 healthy female, asymptomatic, age-matched control subjects. In phase 2, 12 OA patients performed an 8-week NMES strength training program. OA patients presented smaller vastus lateralis thickness (11.9 mm) and fascicle length (20.5%) than healthy subjects (14.1 mm; 24.5%), and also had a 23% smaller knee extensor torque compared to the control group. NMES training increased vastus lateralis thickness (from 12.6 to 14.2 mm) and fascicle length (from 19.6% to 24.6%). Additionally, NMES training increased the knee extensor torque by 8% and reduced joint pain, stiffness, and functional limitation. In conclusion, OA patients have decreased strength, muscle thickness, and fascicle length in the knee extensor musculature compared to control subjects. NMES training appears to offset the changes in quadriceps structure and function, as well as improve the health status in patients with knee OA.

Imaging the operation of a carbon nanotube charge sensor at the nanoscale.

Carbon nanotube field effect transistors (CNTFETs) are of great interest for nanoelectronics applications such as nonvolatile memory elements (NVMEs) or charge sensors. In this work, we use a scanning-probe approach based on a local charge perturbation of CNTFET-based NVMEs and investigate their fundamental operation from combined transport, electrostatic scanning probe techniques and atomistic simulations. We experimentally demonstrate operating devices with threshold voltages shifts opposite to conventional gating and with almost unchanged hysteresis. The former effect is quantitatively understood as the emission of a delocalized image charge pattern in the nanotube environment, in response to local charge storage, while the latter effect points out the dominant dipolar nature of hysteresis in CNTFETs. We propose a simple model for charge sensing using CNTFETs, based on the redistribution of the nanotube image charges. This model could be extended to gas or biosensing, for example.

Desequilíbrios musculares entre flexores dorsais e plantares do tornozelo apóstratamento conservador e acelerado da ruptura do tendão calcâneo / Muscle imbalance between ankle dorsiflexors and plantarflexors after conservative and accelerated treatment of Achilles tendon rupture

A ruptura do tendão calcâneo (TC) reduz a sobrecarga mecânica dos flexoresplantares (FP) do tornozelo. Essa alteração muda o equilíbrio natural entre os FP eflexores dorsais (FD) do tornozelo. O objetivo do estudo foi avaliar as razões isocinéticas concêntricas convencionais de torque de pacientes submetidos a tratamento cirúrgico de ruptura aguda do TC após dois protocolos diferentes de reabilitação. Após procedimento cirúrgico para reconstrução do TC, a amostra foi dividida de forma intencional em dois grupos: conservador (GC, 11 homens, 41,3±7,9 anos) e grupo acelerado (GA, 13 homens, 43,5±13,7 anos). O GC permaneceu com imobilização gessada no tornozelo por seis semanas (tratamento tradicional), enquanto o GA usou uma órtese robofoot em posição neutra e, após duas semanas, iniciou mobilização e apoio precoce do tornozelo, com reabilitação por seis semanas. Após 3 meses de pós-operatório, a razão do torque concêntrico máximo dos FD pelos FP do tornozelo foi avaliada por dinamômetro isocinético. As razões de torque do lado operado se mantiveram superiores às do lado saudável mesmo após 3 meses de pós-operatório (p<0,05). Não foi encontrada diferença no equilíbrio muscular entre os grupos. Pode-se concluir que os dois grupos requerem um período mais longo de reabilitação para recuperar o equilíbrio natural do tornozelo no lado operado.

Achilles tendon rupture reduces ankle plantarflexor (PF) muscles mechanical overload. This change in the ankle joint mechanics changes the natural muscle balance between dorsiflexor (DF) and PF muscles. The purpose of this study was toassess such imbalance by concentric conventional isokinetic torque ratios of patients who underwent different rehabilitation protocols after surgical repair of the Achilles tendon. After surgery, subjects were assigned to either a conservative or to an accelerated rehabilitation group. The conservative group (11 men, 41.3±7.9 years old) remained with a plaster cast for 6 weeks after surgery. The accelerated group (13 men, 43.5±13,7 years old) used a “robofoot” cast for 2 weeks and under wentankle mobilization and early weight bearing for a period of 6 weeks post immobilization. At 3 months post-surgery the ratio between the maximal concentric DF torque and the maximal concentric PF torque was evaluated with an isokinetic dynamometer. Torque ratios on the surgery side were higher (p<0.05) than on the sound side in both groups. No differences of muscle balance could be found between the groups. These results suggest that both groups require further rehabilitation to regain the natural muscle balance between surgery-side ankle DF and PF muscles.

Indicadores para gestão da pesquisa clínica: primeiras anotações

Este trabalho está voltado a uma reflexão metodológica sobre o conceito de indicadores de desempenho dirigido a atividade de gestão da pesquisa clínica no âmbito de um hospital de ensino. O contexto de estudo é o Grupo Hospitalar Conceição (GHC), Porto Alegre/RS, e a perspectiva de análise parte de sua Gerência de Controladoria. Mais especificamente, trata-se do monitoramento das atividades de requisição de orçamento e estimativa de receitas dos Projetos de Pesquisa Clínica encaminhadas à Gerência de Ensino e Pesquisa (GEP). Por meio de pesquisa qualitativa, com base documental e entrevistas, a intenção é discutir a importância fundamental dos indicadores para as atividades de gestão, e apontar para a necessidade de construí-los, de forma coletiva, com vistas ao desenvolvimento de metodologias que possibilitem as melhores práticas de gestão da pesquisa clínica.