Experimental observation of a complex periodic window

The existence of a special periodic window in the two-dimensional parameter space of an experimental Chua's circuit is reported. One of the main reasons that makes such a window special is that the observation of one implies that other similar periodic windows must exist for other parameter values. However, such a window has never been experimentally observed, since its size in parameter space decreases exponentially with the period of the periodic attractor. This property imposes clear limitations for its experimental detection.Comment: 4.2 pages, 4 figure

Dynamical estimates of chaotic systems from Poincar\'e recurrences

We show that the probability distribution function that best fits the distribution of return times between two consecutive visits of a chaotic trajectory to finite size regions in phase space deviates from the exponential statistics by a small power-law term, a term that represents the deterministic manifestation of the dynamics, which can be easily experimentally detected and theoretically estimated. We also provide simpler and faster ways to calculate the positive Lyapunov exponents and the short-term correlation function by either realizing observations of higher probable returns or by calculating the eigenvalues of only one very especial unstable periodic orbit of low-period. Finally, we discuss how our approaches can be used to treat data coming from complex systems.Comment: subm. for publication. Accepted fpr publication in Chao

Experimental dynamic evaluation of three-phase reactors

The hydrodynamic parameters were determined for two different three-phase systems (fluidized-bed and trickle-bed) through the experimental evaluation of the dynamic residence time distribution in the gas or liquid phase. For different fluid phase flow rates the fluidized-bed system was operated with a tracer in the gas phase and in the trickle-bed with a tracer in the liquid phase. The analysis of the processes was achieved through the application of different models representing the dynamic behavior of tracers present in the gas and liquid phases with a simulation of experimental operations of the three-phase reactors. The transfer functions developed for the two systems made it possible to estimate the hydrodynamic parameters providing the gas holdup (2.22 x 10-2 to 8.42 x 10-2) and the gas phase Peclet number (54.18 to 41.20) for the fluidized-bed and the liquid holdup (0.16 to 0.25), the liquid phase Peclet number (20.37 to 4.52) and wetting efficiency (0.34 to 0.56) for the trickle-bed.443452Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

Determination of Cd and Pb in fuel ethanol by filter furnace electrothermal atomic absorption spectrometry

A method was developed for quantification of Cd and Pb in ethanol fuel by filter furnace atomic absorption spectrometry. Filter furnace was used to eliminate the need for chemical modification, to stabilize volatile analytes and to allow the application of short pyrolysis step. The determinations in samples were carried out against calibration solutions prepared in ethanol. Recovery tests were made in seven commercial ethanol fuel samples with values between 90 and 120%. Limits of detection were 0.1 µg L-1 for Cd and 0.3 µg L-1 for Pb. Certified water samples (APS 1071, APS 1033, NIST 1643d, NIST 1640) were also used to evaluate accuracy and recoveries from 86.8% to115% were obtained

Modelling \u3ci\u3eLeucaena\u3c/i\u3e Biomass Under Rainfed Production Systems of Semiarid Regions

The climatic variability of semiarid regions is the main source of uncertainties associated with forage and animal production, indicating a need for tools that accurately estimate forage production in order to construct a forage budgeting plan for livestock. This study simulated the biomass of Leucaena (Leucaena leucocephala) using the PHYGROW model in four locations located in Brazilian Semiarid. The work was carried out based on field data collected from 2019 to 2021. After sowing in 2018, leucaena was harvested when it reached 200 cm and to a target residual height of 70 cm. The biomass (fresh matter) was weighed, sampled and dried to obtain the total forage biomass (BFT) of each sample. The BFT was also estimated using the PHYGROW model, with field data being used to parameterize, calibrate and validate the model. The model performance, in turn, was evaluated based on the mean forecast error (BIAS %), root mean square error (RMSE) and Willmott index. Afterwards, a BFT time series was downloaded for each location, with the highest biomass simulated for each year being evaluated in the @Risk regarding their probability distribution. Thereafter, probability calculations of biomass production were performed, based on different levels of warranty in SigmaPlot software (11.0). The model underestimated the BFT collected in two locations and overestimated BFT in the others. The Weibull function was the best one to describe the data. Regarding biomass production under a 95% natural warranty, it was observed that leucaena showed low variation among locations (2240 ± 752 kg of DM ha-1 year-1 ). The PHYGROW model accurately predicted the leucaena BFT which, in turn, demonstrated significant adaptation potential to the various soil and climate conditions of Brazilian Semiarid. The use of probability analysis can contribute to forage planning, thus reducing the uncertainties related to climate variability, especially in rainfed production systems of dry areas

Cactus Forage Productivity Modelling Using PHYGROW Software in a Semiarid Environment

Plant growth modeling has been shown an increasing strategy to cope with the high demand for food supply, mainly in climate vulnerable areas, providing them to be used in agriculture worldwide. Concerning semiarid regions, the PHYGROW software has been promising to model plant growth, as cactus forage (‘Opuntia stricta’ cv. “Mexican elephant ear”) which was used in this study. Production data from 2017 and 2018 in Petrolina, Permambuco state, Brazil, with 12 replicates each year were considered. This region shows a very hot and dry climate and has an erratic and seasonal rainfall, which varies a lot in quantity, frequency and intensity from one year to another. After the PHYGROW software parameterization, we performed the generation of the synthetic series and, afterwards, we add the field data to calibration and validation. The results showed a high prediction capacity of PHYGROW software, even in such an erratic climate as Brazilian Semiarid, considering the model performed as calibrated. In 2017 and 2018, the observed cactus forage biomass were 1745 ± 505.83 and 2016 ± 584.58 kg DM ha-1 and the estimated data were 1795 and 2314 kg DM ha-1, respectively. This relatively high deviation suggests an opportunity to add more data, in order to get the model more accurate. Although there was a high difference in precipitation from 2017 to 2018 (166 and 301 mm, respectively), cactus forage was capable to offset this fluctuation, which makes it a strategic resource to reduces the biomass variation and stockpiling necessity on the farm level. This study also demonstrated the importance of modelling to help the farmer to cope with the weather and feed variation in climate vulnerable areas, allowing them to anticipate and adopt strategies to cope with drought more efficiently

Índices de crescimento em capim-paraíso sob diferentes idades durante três ciclos de crescimento no litoral cearense.

Resumo: As forrageiras apresentam variação ao longo do seu crescimento, em razão de variação na idade fisiológica e das condições de meio e manejo. Objetivou-se avaliar os índices de crescimento em capim-paraíso em diferentes idades de crescimento (14; 21; 28; 35; 42; 49; 56; 63 e 70 dias) e durante três ciclos (chuvoso, seco 1 e seco 2), num delineamento inteiramente casualizado com medidas repetidas no tempo e duas repetições. Avaliaram-se a taxa de crescimento relativo (TCR), a razão de área foliar (RAF), a razão de peso foliar (RPF) e a área foliar específica (AFE). A interação entre idades de crescimento e ciclos foi significativa para todas as variáveis analisadas, exceto para a AFE. A TCR decresceu com as idades em ambos os ciclos, exceto no ciclo seco 2, com média de 0,0512 g?g-1?dia-1. A RAF e a RPF decresceram com o avanço nas idades. A AFE respondeu positivamente às idades. As idades de crescimento influenciam a dinâmica dos componentes morfofisiológicos do capim-paraíso. [Growth index in paraiso grass under different ages during three growth cycles in coastal Ceara]. Abstract: The forage plants show variation along their growth due to changes in physiological age, environment and management conditions. One aimed to analyze the growth index of paraiso grass, in different growth ages (14; 21; 28; 35; 42; 49; 56; 63 e 70 days) and cycles (rainy, dry 1 and dry 2). A completely randomized design in a split-plot layout with repeated measures and two replicates was adopetd. The relative growth rate (RGR), the leaf area ratio (LAR), the leaf weight ratio (LWR) and the specific leaf area (SLA) were evaluated. An interaction between growth ages and cycles was observed for all variable analyzed, except for SLA. The RGR showed a linear decreased effect in the cycles, except in dry 2 cycles, with an average of 0,0512 g?g-1?day-1. The LAR and LWR decreased along the ages. The SLA presented positive linear effect. The different growth ages influenced the morphofisiological components in paraiso grass

Previous exercise training increases levels of PPAR-α in long-term post-myocardial infarction in rats, which is correlated with better inflammatory response

OBJECTIVE: Exercise is a protective factor for cardiovascular morbidity and mortality, with unclear mechanisms. Changing the myocardial metabolism causes harmful consequences for heart function and exercise contributes to metabolic adjustment modulation. Peroxisome proliferator-activated receptors (PPARs) are also myocardium metabolism regulators capable of decreasing the inflammatory response. We hypothesized that PPAR-α is involved in the beneficial effects of previous exercise on myocardial infarction (MI) and cardiac function, changing the expression of metabolic and inflammatory response regulators and reducing myocardial apoptosis, which partially explains the better outcome. METHODS AND RESULTS: Exercised rats engaged in swimming sessions for 60 min/day, 5 days/week, for 8 weeks. Both the exercised rats and sedentary rats were randomized to MI surgery and followed for 1 week (EI1 or SI1) or 4 weeks (EI4 or SI4) of healing or to sham groups. Echocardiography was employed to detect left ventricular function and the infarct size. Additionally, the TUNEL technique was used to assess apoptosis and immunohistochemistry was used to quantitatively analyze the PPAR-α, TNF-α and NF-κB antigens in the infarcted and non-infarcted myocardium. MI-related mortality was higher in SI4 than in EI4 (25% vs 12%), without a difference in MI size. SI4 exhibited a lower shortening fraction than EI4 did (24% vs 35%) and a higher apoptosis/area rate (3.97±0.61 vs 1.90±1.82) in infarcted areas (both p=0.001). Immunohistochemistry also revealed higher TNF-α levels in SI1 than in EI1 (9.59 vs 4.09,

Accumulation and export of nutrients in cactus pear cladodes (Opuntia ficus-indica) under different managements in the Brazilian Semiarid.

Abstract: The present study evaluated the accumulation and export of nutrients in cactus pear (Opuntia ficus-indica) cv. Gigante, fertilized with combinations of nitrogen (10, 70, 100, 130, and 190 kg ha -1 year -1 N) and phosphorus (10, 70, 100, 130, and 190 kg ha -1 year -1 P2O5) under annual and biennial harvests, in Quixadá and Tejuçuoca, using a split-plot randomized block design with four replications. In Quixadá, under annual and biennial harvests, the following orders of accumulation of macronutrients (in kg ha -1 year -1) were found, respectively: K (98.8) > Ca (87.2) > N (46.7) > Mg (26.8) > S (18.4) > P (2.04) and Ca (33.5) > K (31.1) > S (18.6) > N (12.9) > Mg (10.5) > P (0.81). In Tejuçuoca, under annual and biennial harvests, the orders of accumulation of macronutrients were, respectively: K (146.5) > Ca (204.6) > N (128.1) > Mg (75.8) > S (50.3) > P (3.7) and K (397.2) > N (191.3) > S (241.2) > Ca (167.8) > Mg (131.0) > P (14.1). The maintenance/production fertilization in cactus pear should be planned according to productive potential, fertilization and harvest managements, and cultivation region, based on nutritional requirement and considering the nutrient recovery efficiency