A Neural Network-Based Random Access Protocol for Crowded Massive MIMO Systems.

Fifth-generation (5G) and beyond networks are expected to serve large numbers of user equipments (UEs). Grant-based random access (RA) protocols are efficient when serving human users, typically with large data volumes to transmit. The strongest user collision resolution (SUCRe) is the first protocol that effectively uses the many antennas at the 5G base station (BS) to improve connectivity performance. In this paper, our proposal involves substituting the retransmission rule of the SUCRe protocol with a neural network (NN) to enhance the identification of the strongest user and resolve collisions in a decentralized manner on the UEs' side. The proposed NN-based procedure is trained offline, admitting different congestion levels of the system, aiming to obtain a single setup able to operate with different numbers of UEs. The numerical results indicate that our method attains substantial connectivity performance improvements compared to other protocols without requiring additional complexity or overhead. In addition, the proposed approach is robust regarding variations in the number of BS antennas and transmission power while improving energy efficiency by requiring fewer attempts on the RA stage.

Environmental risk assessment of potentially toxic elements in Doce River watershed after mining sludge dam breakdown in Mariana, MG, Brazil.

Faced with a potential risk of a colossal amount of sludge released into the Doce River basin in the most shocking Brazilian mining disaster, we proposed to assess the environmental risk from a new perspective: Understanding the mobilization of potentially toxic elements (PTE) with the geochemical fractions. Soil and sediment samples were taken in nine sites throughout the basin and characterized. The environmental risk was assessed from the PTE sequential extraction in three fractions: soluble, reducible, and oxidizable, in addition to the pseudo-total concentration. The potential mobile fraction (PMF) showed a considerable PTE mobilization from the soil and sediment samples. Principal component statistical analysis indicated the sludge as the single source of PTE. The risk assessment depended on the fractional distribution and the PTE enrichment degree in the affected samples. The fractional distribution contributed mainly to Mn, Sb, and Pb mobility, with PMF of 96%, 81%, and 100%, respectively. The mobilization of Cd, Co, Ag, Ni, Pb, Zn, and Cu was predominantly related to the degree of enrichment. The risk assessment from the geochemical fractions pointed to the magnitude of the disaster and the dispersion of PTE with severe effects on the affected populations. Therefore, more strongly enforced regulations in the basin are needed, in addition to the urgent use of more secure containment dams. It is also essential to emphasize the transferability of the design of this study to other environmental units in mining disaster conditions.

Separating selenium species by diffusion in Brazilian bentonite: a mathematical modeling approach.

Bentonite was applied in diffusive studies for selenium, an emerging contaminant. The planar source method was used to determine the apparent and effective diffusion coefficients and assess the mobility of the selenium species. A double Gaussian function described the results. Different diffusion coefficients were associated with different mobilities, and consequently, to the coexistence of two selenium species: selenite and selenate. Apparent diffusion coefficients were higher for selenate, around 10- 10 m2 s- 1, than for selenite, around 10- 12 m2 s- 1. Results from sequential extraction and distribution coefficient justified selenate's greater mobility than selenite. Since the increase in redox potential from 448 to 511 mV may be associated with selenite oxidation in an interconversion process, the diffusion in bentonite demonstrates that applications in geological barriers deserve attention regarding the mobilization of selenium species. Interconversions can mobilize selenium, as reduced species can shift to more oxidized and mobile species, enhancing environmental contamination.

Modeling the kinetics of potentially toxic elements desorption in sediment affected by a dam breakdown disaster in Doce River - Brazil.

On November 5th, 2015, a mining dam spilled a huge plume of mining waste in the Doce River. Even though many studies have reported the environmental impact from the Doce River's tragedy, the transport of potentially toxic elements (PTE) by kinetic modeling to determine how long the basin takes to achieve the natural balance has not been described. Therefore, samples of sludge, sediment, and water were collected along the Doce River basin, to assess the elements' total leaching by kinetic modeling. The elements Fe, Al, Mn, Cu, Ag, Pb, Cd, and As were evaluated. An innovative mobilization factor (FS/D) indicated that Mn2+, Ag+, and Cd2+ can be mobilized about 80, 89, and 57 times more than its initial concentration. Besides, in low pH, the Al and Pb ions can be mobilized. The desorption kinetics showed a lower rate constant (k) and higher initial desorption constant (h) for Mn2+ than Cd2+ and Ag+, suggesting both high- and low-affinity interaction sites for Mn2+. The exponential decay demonstrated that metals can leach for months or years. Thus, the long-lasting release of metals from mining tailing waste in concentrations that endanger the ecosystem and human health makes clear the need for long-term monitoring.

A new approach to evaluate toxic metal transport in a catchment.

Competitive sorption and desorption of Cd2+, Pb2+, and Hg2+ onto riverbank and sediment samples of an area impacted by pyritic residue in a Southern Brazilian catchment were evaluated. Although these ions are considered poorly mobile, a new approach has been proposed to assess their behavior and associated risk. In this sense, factorial design and three-dimensional surface methodology are proposed to describe the competitive sorption behavior of the metal ion in the environmental matrix, as well as an innovative mobilization factor (MF) to describe the desorption rate from the integration of the normalized difference of sorption-desorption fluorescence peaks. Sorption was carried out with a central composite factorial design (23) to estimate simultaneous effects of independent variables. Three-dimensional surface analysis indicated increasing Cd2+ equilibrium concentration (Ceq) with Hg2+ and Pb2+ initial concentration (Ci), showing synergistic effect and low Cd2+ affinity to the solid phase. Statistical analysis presented [Formula: see text] as a significant variable for cadmium and lead dynamics, although [Formula: see text] was also significant for Hg2+ releasing to the liquid phase. After integrating the sorption and desorption fluorescence peaks, the MF for Cd2+, Pb2+, and Hg2+ was around 0.2, 0.5, and 0.1 in riverbank sediment, and 0.3, 0.9, and 0.1 in sediment, respectively. Hence, consistent ion mobilization along the river was observed, with Pb2+ mobilizing 9 and 6 times more than Hg2+ and Cd2+, respectively. The transport of ions such as Pb2+ and Hg2+, usually considered immobile, has indeed occurred, causing contamination through the watershed and increasing environmental risk. Graphical Abstract A new approach to determine toxic metal mobilization factor in a river catchment.

Predistortion and pre-equalization for nonlinearities and low-pass effect mitigation in OFDM-VLC systems.

The orthogonal frequency division multiplexing (OFDM) transmission is a promising candidate for visible light communication (VLC) applications. However, the nonlinearity in the optical power emitted by the high-power light-emitting diode (HPLED) as a function of current and temperature implies drastic OFDM-VLC performance degradation. The first part of this work experimentally confirms and models this degradation due to temperature in a white HPLED. The higher attenuation at high frequencies, which is inherent to the HPLED and which is accentuated by the effect of the intrinsic capacitance of the photodiode, is another factor of degradation due to the reduction in the signal-to-noise ratio (SNR) at the receiver for such frequencies. For the mitigation of these combined effects, we propose a predistortion and a digital pre-equalization scheme using a luminous feedback signal at the transmitter side. The VLC system is modeled so that the operating points are mathematically deduced and evaluated by simulations and by an experimental setup. By allowing the linearization of the transmitted light signal and the maintenance of a uniform SNR among all OFDM subcarriers, the performance improvement is confirmed in comparison with other schemes, such as a VLC system without predistortion, predistortion with fixed parameters, as well as a simple post-equalization.

Sorption-desorption of antimony species onto calcined hydrotalcite: Surface structure and control of competitive anions.

Calcined hydrotalcite can be applied to remove anionic contaminants from aqueous systems such as antimony species due to its great anion exchange capacity and high surface area. Hence, this study evaluated antimonite and antimonate sorption-desorption processes onto calcined hydrotalcite in the presence of nitrate, sulfate and phosphate. Sorption and desorption experiments of antimonite and antimonate were carried out in batch equilibrium and the post-sorption solids were analyzed by X-ray fluorescence (EDXRF). Sorption data were better fitted by dual-mode Langmuir-Freundlich model (R2>0.99) and desorption data by Langmuir model. High maximum sorption capacities were found for the calcined hydrotalcite, ranging from 617 to 790meqkg-1. The competing anions strongly affected the antimony sorption. EDXRF analysis and mathematical modelling showed that sulfate and phosphate presented higher effect on antimonite and antimonate sorption, respectively. High values for sorption efficiency (SE=99%) and sorption capacity were attributed to the sorbent small particles and the large surface area. Positive hysteresis indexes and low mobilization factors (MF>3%) suggest very low desorption capacity to antimony species from LDH. These calcined hydrotalcite characteristics are desirable for sorption of antimony species from aqueous solutions.

Sorption-desorption of selenite and selenate on Mg-Al layered double hydroxide in competition with nitrate, sulfate and phosphate.

Selenate and selenite are considered emerging contaminants and pose a risk to living organisms. Since selenium anion species are at low concentration in aquatic environments, materials for its retention are required to enable monitoring. Herein, hydrotalcite was calcined and characterised to investigate sorption and desorption of selenite and selenate in competition with nitrate, sulfate and phosphate. Sorption experiments were carried out in batch system and desorption by sequential dilution. Selenite and selenate concentration remaining after N desorption steps was determined by mass balance. The isotherms were adjusted to the dual-mode Langmuir-Freundlich model (R2 > 0.99). Maximum sorption capacity ranged from 494 to 563 meq kg-1 for selenite and from 609 to 659 meq kg-1 for selenate. Sulfate and phosphate ions showed greater competitive effect on the sorption of selenate and selenite, respectively. Low mobilization factors and high sorption efficiency (MF<3%; SE ≈ 100%) indicated that calcined hydrotalcite has the wanted characteristics for retention of relevant selenium anion species in aqueous media.

Sorption and desorption of silver ions by bentonite clays.

Anthropogenic activities have increased the concentration of metal species in the environment. The toxicity of silver ions to aquatic and terrestrial organisms has required monitoring by analytical methods, besides actions to promote its control as pollutant. Sorption and desorption processes are directly related to the mobility and availability of metal ions in the environment. In this context, clay minerals can be used for pre-concentration, removal and recovery of silver ions from aqueous solution. Herein, two bentonite clays (BaVC-1 and SWy-2) were characterised and applied to investigate the sorption and desorption of silver ions. Isotherms were fitted to the dual-mode Langmuir-Freundlich model to qualify and quantify sorption sites and evaluate the mobilisation process. The maximum sorption capacity was 743 and 849 meq kg-1 for BaVC-1 and SWy-2, respectively. Hysteresis index (HI) and mobilisation factor (MF) suggest that the desorption of silver ions in BaVC-1 is about four times more conducive compared to that in SWy-2, although both materials have demonstrated a great potential for Ag+ pre-concentration from aqueous solutions.

MIMO transmit scheme based on morphological perceptron with competitive learning.

This paper proposes a new multi-input multi-output (MIMO) transmit scheme aided by artificial neural network (ANN). The morphological perceptron with competitive learning (MP/CL) concept is deployed as a decision rule in the MIMO detection stage. The proposed MIMO transmission scheme is able to achieve double spectral efficiency; hence, in each time-slot the receiver decodes two symbols at a time instead one as Alamouti scheme. Other advantage of the proposed transmit scheme with MP/CL-aided detector is its polynomial complexity according to modulation order, while it becomes linear when the data stream length is greater than modulation order. The performance of the proposed scheme is compared to the traditional MIMO schemes, namely Alamouti scheme and maximum-likelihood MIMO (ML-MIMO) detector. Also, the proposed scheme is evaluated in a scenario with variable channel information along the frame. Numerical results have shown that the diversity gain under space-time coding Alamouti scheme is partially lost, which slightly reduces the bit-error rate (BER) performance of the proposed MP/CL-NN MIMO scheme.

Leachability of major and minor elements from soils and sediments of an abandoned coal mining area in Southern Brazil.

Leachability of major and trace elements from sediment and soil samples of an abandoned coal mining area in southern Brazil was assessed by titration and pH-stat tests according to the SR002.1 and CEN/TS 14429 protocols. Major (Al, Fe, Ca, Mg, and Mn) and trace (Cu, Zn, As, Ni, Pb, Cd, and Hg) elements were quantified in aqueous extracts. Acid and base neutralizing capacity values and pH changes after the addition of certain acid/base amounts were estimated. In general, a decrease in the major metal leaching at pH < 4.0 and an increase at pH > 8.0 was observed. The response to the acid and base additions confirmed that strong acids can cause an effect on Ca- and Mg-bearing silicate phases and Mn oxides, and strong bases can only affect Ca silicates. At pH < 5.0, higher extractability was found for Cu, Zn, Ni, Pb, and Cd. Considering that the samples showed sharp pH changes after acid additions and released major and trace metal into the solution at greater rates, high metal contamination risks can be assumed for the studied area.

Comparison of the electromyographic activity of the anterior trunk during the execution of two Pilates exercises - teaser and longspine - for healthy people.

This study compared abdominal electromyographic (EMG) activity during the performance of Pilates' exercises. 16 females participated in the study. EMG signals of the rectus abdominis (RA) and external oblique (EO) were recorded during Longspine performed on the mat, Cadillac, and Reformer and the Teaser performed on the mat, Cadillac, and Combo-chair. Values were normalized by the EMG peak of a dynamic task and divided in concentric and eccentric phases. Longspine performed on the mat increased EO activity in the concentric phase more than on the Reformer and the Cadillac (Mean Difference (MD)=12.2%; 95% Confidence Interval (CI) [3.36; 21.04]; p=.04). Differences in the eccentric phase of the RA favored the mat compared to the Reformer (MD=5.20%; 95% CI [-0.55; 10.95]; p=.02). Significant differences in eccentric contraction of the RA were found for teaser exercise performed on the mat versus Cadillac (MD=1.1%; 95% CI [-4.13; 6.33]; p=.04) and the mat versus the Combo-chair (MD=6.3%; 95% CI [1.31; 11.29]; p=.005). Higher concentric activation values for the EO were found when the teaser exercise was performed on the Cadillac. Exercises performed on the mat required greater rectus abdominis activation.

Cadmium mobility in sediments and soils from a coal mining area on Tibagi River watershed: environmental risk assessment.

The risk of cadmium contamination in the Tibagi River watershed (Parana State, Brazil) affected by past coal mining activities was assessed through sorption-desorption modeling for sediment and soil samples. The acidic character of the samples resulted in more competition between the cadmium ions and protons, thereby influencing the cadmium sorption-desorption. The sorption isotherms were fitted to the Langmuir and Freundlich single models and to the dual-site Langmuir-Freundlich (or Sips) model. The single-site models indicated a low-energy character of sorption sites on the sample sorption sites, whereas the dual-site model explained the availability of higher-affinity and lower-affinity non-specific sites. The correlation of the sorption and desorption constants with the physicochemical and mineralogical characteristics of the samples showed that the cadmium sorption behavior was significantly affected by the pH, point of zero charge, and also by the magnesium, aluminum, calcium and manganese amounts. Besides, the desorption rate and hysteresis index suggested a high risk of cadmium mobilization along the Tibagi River basin.

The electromyographic activity of the multifidus muscles during the execution of two pilates exercises--swan dive and breast stroke--for healthy people.

OBJECTIVE: The purpose of this study was to compare the multifidus electromyographic activity in healthy women during the performance of the same Pilates exercise under 2 conditions. METHODS: Sixteen healthy, active, female practitioners of Pilates (mean age, 24.3; SD, 3.1 years) were assessed through surface electromyography during 2 Pilates exercises (swan dive and breast stroke). Muscle activity during the experimental tasks was recorded with 1 pair of electrodes placed bilaterally on the multifidi. Data were normalized to maximal activity recorded during dynamic activity. RESULTS: The mean of the maximal isometric voluntary contraction was 662.4 N (SD, 195). In the phase comparison, the multifidus was the most recruited on the concentric phase during both exercises, ball (P=.001) and reformer (P=.001). In the comparison between conditions, the reformer presented more activation on swan dive (P=.04) and breast stroke (P=.001). The percentages of muscle activation varied between 50% and 60%, and the greatest activation was made on the reformer condition. CONCLUSION: The findings of this study show that Pilates exercises by healthy women, under different conditions, can cause changes to the multifidus muscle activation. The condition and the phase in which the muscle was more activated were the reformer and concentric phase, respectively, for both exercises. However, the results for the percentages of activation suggest that the intensity of recruitment may not be sufficient to strengthen muscle in healthy, trained subjects.

A comparative analysis of the electrical activity of the abdominal muscles during traditional and Pilates-based exercises under two conditions / Análise comparativa da atividade elétrica dos músculos abdominais durante exercício tradicional e método pilates sob duas condições

The use of Pilates-based exercises for trunk strengthening has been reported in the literature. The objective of this study was to analyze and compare the electrical activity of the rectus abdominis and external oblique muscles during a traditional abdominal exercise program and an exercise program based on the Pilates method using a ball and an elastic band. The sample was composed of 10 healthy women, non-practitioners of Pilates, who performed the traditional abdominal exercise and roll-up with the ball and elastic band. The sign was normalized by the electromyographic peak of the dynamic activity and was adjusted for 2000 samples/s; the filter was set in a frequency band from 20 to 450 Hz. In the comparison between exercises, the external oblique muscle in the concentric phase had a higher recruitment in the roll-up with the ball (P = 0.042). In the comparison between muscles in each exercise, the rectus abdominis showed a higher activation in the concentric phase (P = 0.009) and in the eccentric phase (P = 0.05) of the traditional abdominal exercise. Activation percentages ranged from 15% to 22%. The traditional abdominal exercise had the largest activation percentage.

Exercícios baseados no método Pilates são relatados na literatura para serem utilizados como proposta de fortalecimento de tronco. O objetivo deste estudo foi analisar e comparar a atividade elétrica dos músculos reto abdominal e oblíquo externo, durante um exercício de abdominal tradicional e um exercício baseado no método Pilates com bola e com faixa elástica. A amostra foi composta por 10 mulheres saudáveis não praticantes de Pilates, que realizaram o exercício de abdominal tradicional e Roll-up com bola e faixa elástica. O sinal foi normalizado pelo pico eletromiográfico da atividade dinâmica e foram ajustados para 2000 amostras por segundo e o filtro em uma frequência de passagem de 20 a 450 Hz. Na comparação entre exercícios, o músculo oblíquo externo na fase concêntrica teve maior recrutamento no Roll-up com bola (P = 0,042). Na comparação entre os músculos em cada exercício, o reto abdominal teve maior ativação nas fases concêntrica (P = 0,009) e excêntrica (P = 0,05) do abdominal tradicional. As porcentagens de ativação variaram de 15% a 22%. O exercício de abdominal tradicional teve a maior porcentagem de ativação.

Análise comparativa da atividade elétrica do músculo multífido durante exercícios do Pilates, série de Williams e Spine Stabilization / Analysis of the multifidus muscle during Pilates, Williams' flexion and Spine Stabilization

INTRODUÇÃO: A fraqueza da musculatura paraespinhal está relacionada à etiologia da dor lombar. Atualmente existem vários métodos que apresentam exercícios para o fortalecimento dessa musculatura. OBJETIVOS: Comparar e analisar o sinal eletromiográfico do músculo multífido bilateralmente durante exercícios do método Pilates, série de Williams e Spine Stabilization. MATERIAIS E MÉTODOS: Participaram do estudo dez mulheres voluntárias e saudáveis que realizaram os exercícios leg pull front support modificado do Pilates, o quarto exercício da série adicional de Williams e o quadruped exercise do Spine Stabilization. O sinal foi normalizado pelo pico eletromiográfico da atividade dinâmica e foram ajustados para 2000 amostras por segundo e o filtro em uma frequência de passagem de 20 a 450 Hz. A ANOVA foi utilizada para verificar diferenças entre os exercícios, o teste t para amostras dependentes foi usado para comparar a ativação entre os lados direito e esquerdo do multífido para cada exercício. RESULTADOS E CONSIDERAÇÕES FINAIS: Na comparação entre os exercícios, observaram-se diferenças significativas para o músculo multífido a favor do exercício do método Pilates tanto na fase concêntrica quanto na excêntrica, o que demonstra ser o exercício de melhor ativação elétrica para o músculo analisado.

INTRODUCTION: The back muscle weakness is related with the etiology of low back pain. Nowadays, there are several methods the focus is on back muscle strengthening. OBJECTIVES: The purpose of this study was to compare and analyze the multifidus muscle bilaterally during exercises of the Pilates method, Spine Stabilization and Williams' flexion. MATERIALS AND METHODS: Ten healthy female volunteers participated in the study. They performed the leg pull front support exercise from the Pilates method, the quadruped exercise from the Spine Stabilization and the fourth exercise from the additional Williams' flexion. The signal was normalized by the electromyographic peak of the dynamic activity and was adjusted to 2000 samples/s and filter with a frequency band from 20 to 450 Hz. ANOVA was used to verify differences between the exercises, the paired-sample t test was used to compare activation between the right and left multifidus for each exercise. RESULTS AND CONCLUSION: When the exercises where compared, statistically significant differences were observed in the concentric and eccentric phases for the Pilates exercise, showing that this exercise is the one who activates the musculature the most between the exercises evaluated.

EMG spectral analysis of incremental exercise in cyclists and non-cyclists using Fourier and Wavelet transforms / Análise espectral do sinal emg de exercício incremental em ciclistas e não ciclistas usando as transformadas de Fourier e Wavelet

The aim of this study was to compare the electromyographic indices of fatigue (slope of median frequency) calculated with the fast Fourier transform (FFT) and wavelet transform (WT) in trained and untrained individuals during cycle exercise. A second objective was to compare the variance of the spectral parameters (median frequency - MF) obtained by the FFT and WT during exercise. Twelve cyclists and non-cyclists performed a maximal incremental test to determine the peak power (Wp) and electromyographic activity of the vastus lateralis (VL), rectus femoris (RF), biceps femoris (BF), semitendinous (ST) and tibialis anterior (TA). Mean values of median frequency, determined by the FFT and WT, were used for the spectral analysis of the electromyographic signals of the studied muscles. The analyzed parameters were obtained for each time period corresponding to 0, 25, 50, 75, and 100% of total duration of the maximal incremental test. No statistically significant differences were found in the values of MF and electromyographic indices of fatigue between the two techniques (FT and WT) both in the cyclists and non-cyclists group (P>0.05). Regarding the MF variance, statistically significant differences were found in all analyzed muscles, as well as in different time periods, both in the cyclists and non-cyclists groups when comparing the FFT and WT techniques (P<0.05). The WT seems to be more adequate to dynamic tasks, since it does not require the signal to be quasi-stationary, unlike the limitation imposed upon the use of the FFT.

O objetivo deste estudo foi comparar índices de fadiga eletromiográfica (inclinação da frequência mediana), calculado com a transformada rápida de Fourier (FFT) e transformada de wavelet (WT) em indivíduos treinados e não treinados durante o exercício de ciclismo. Um segundo objetivo foi o de comparar a variância dos parâmetros espectrais (frequência mediana - MF), obtidos por FFT e WT durante o exercício. Doze ciclistas e doze não ciclistas realizaram um teste incremental máximo, para determinar a potência pico (Wp) e atividade eletromiográfica do vasto lateral (VL), reto femoral (RF), bíceps femoral (BF), semitendíneo (ST) e tibial anterior (TA). Os valores médios da frequência mediana determinados pelo FFT e WT, foram utilizados para a análise espectral dos sinais eletromiográficos dos músculos estudados. Os parâmetros avaliados foram obtidos para cada período de tempo correspondente a 0, 25, 50, 75 e 100% da duração total do teste incremental máximo. Nenhuma diferença estatisticamente significativa foi encontrada nos valores da MF e índices eletromiográficos de fadiga entre as duas técnicas utilizadas (FT e WT), em ambos os grupos, ciclistas e não ciclistas (P> 0,05). Quanto à variância da MF, as diferenças estatisticamente significativas foram encontradas em todos os músculos analisados, bem como em diferentes períodos de tempo, tanto nos ciclistas quanto nos não ciclistas, quando se compara as técnicas FFT e WT (P <0,05). A WT parece ser mais adequada para tarefas dinâmicas, uma vez que não requer que o sinal a ser quase estacionário, ao contrário da limitação imposta ao uso da FFT.

Examination of competitive lanthanide sorption onto smectites and its significance in the management of radioactive waste.

The competitive effect of La and Lu (analogues of radionuclides appearing in radioactive waste) in the sorption in four smectites was examined. Sorption and desorption distribution coefficients (K(d); K(d,des)), and desorption rates (R(des)) were determined from batch tests in two media: deionized water and, to consider the influence of cement leachates, 0.02 mol L(-1) Ca. The competitive effect was lower when high-affinity sites were available, as in the water medium at the lowest range of initial lanthanide concentration, with high K(d) for La and for Lu (5-63×10(4) L kg(-1)). Lower K(d) was measured at higher initial concentrations and in the Ca medium, where Lu showed a stronger competitive effect. This was confirmed by fitting the sorption data to a two-solute Langmuir isotherm. The desorption data indicated that sorption was virtually irreversible for the scenarios with high sorption, with an excellent correlation between K(d) and K(d,des) (R(2) around 0.9 for the two lanthanides). Assuming that radioactive waste is a mixture of radionuclides, and that Ca ions will be provided by the cement leachates, this would reduce the retention capacity of clay engineered barriers.

Fourier and wavelet spectral analysis of EMG signals in isometric and dynamic maximal effort exercise.

Frequency domain analyses of changes in electromyographic (EMG) signals over time are frequently used to assess muscle fatigue. Fourier based approaches are typically used in these analyses, yet Fourier analysis assumes signal stationarity, which is unlikely during dynamic contractions. Wavelet based methods of signal analysis do not assume stationarity and may be more appropriate for joint time-frequency domain analysis. The purpose of this study was to compare Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) in assessing muscle fatigue in isometric and dynamic exercise. The results of this study indicate that CWT and STFT analyses give similar fatigue estimates (slope of median frequency) in isometric and dynamic exercise (P>0.05). However, the results of the variance was lower for both types of exercise in CWT compared to STFT (P < 0.05) indicating more variability in the EMG signal analysis using STFT. Thus, the stationarity assumption may not be the sole factor responsible for affecting the Fourier based estimates.

Fourier and wavelet spectral analysis of EMG signals in maximal constant load dynamic exercise.

Frequency domain analyses of changes in electromyographic (EMG) signals over time are frequently used to assess muscle fatigue. Fourier based approaches are typically used in these analyses, yet Fourier analysis assumes signal stationarity, which is unlikely during dynamic contractions. Wavelet based methods of signal analysis do not assume stationarity and may be more appropriate for joint time-frequency domain analysis. The purpose of this study was to compare Short-Time Fourier Transform (STFT) and Continuous Wavelet Transform (CWT) in assessing muscle fatigue in maximal constant load dynamic exercise (100% W(max)). The results of this study indicate that CWT and STFT analyses give similar fatigue estimates (slope of median frequency) in maximal constant load dynamic exercise (P>0.05). However, the results of the variance was significantly lower for at least one of the muscles studied in CWT compared to STFT (P〈0.05) indicating more variability in the EMG signal analysis using STFT. Thus, the stationarity assumption may not be the sole factor responsible for affecting the Fourier based estimates.