791 resultados para content recommendation


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Few studies in Brazil have addressed the need for micronutrients of physic nut focusing on physiological responses, especially in terms of photosynthesis. The objective of this study was to evaluate the effects of omission of boron (B), copper (Cu), iron (Fe), manganese (Mn) and zinc (Zn) on Jatropha curcas L.. The experimental design was a randomized block with four replications. The treatments were complete solution (control) and solution without B, Cu, Fe, Mn, and Zn. We evaluated the chlorophyll content (SPAD units), photosynthetic rate, dry matter production and accumulation of micronutrients in plants, resulting from different treatments. The first signs of deficiency were observed for Fe and B, followed by Mn and Zn, while no symptoms were observed for Cu deficiency. The micronutrient omission reduced the dry matter yield, chlorophyll content and photosynthetic rate of the plants differently for each omitted nutrient. It was, however, the omission of Fe that most affected the development of this species in all parameters evaluated. The treatments negatively affected the chlorophyll content, evaluated in SPAD units, and the photosynthetic rate, except for the omission of B. However this result was probably due to the concentration effect, since there was a significant reduction in the dry matter production of B-deficient plants.

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Oxygen content is a very important factor influencing the electrical properties of YBa2Cu3Oy. In this work the electrical properties of laser deposited YBa2Cu3Oy thin films on LaAlO3(100), in the whole range 6 y 7, are studied. An electrical network model, which randomly assigns oxygen contents and R(T) characteristics to the different elements in the circuit according to an arbitrary distribution, is used to analyze several features in the measured R(T) characteristics as a function of oxygen homogeneity. The model takes into account both short-range and long-range oxygen inhomogeneities. Good agreement between estimated oxygen contents from x-ray diffraction data in our samples and the average oxygen contents used to reproduce their R(T) characteristics is found. The model points out that oxygen homogeneity is very important in order to get the best and reproducible properties, and for conduction and superconductivity analysis through the shape or derivatives of R(T) characteristics.

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Selostus: Suolamerkinnät valintamyymälöiden pakatuissa elintarvikkeissa

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The application of animal manure to soil can increase phosphorus availability to plants and enhance transfer of the nutrient solution drained from the soil surface or leached into the soil profile. The aim of this study was to evaluate the effect of successive applications of organic and mineral nutrient sources on the available content, surface runoff and leaching of P forms in a Typic Hapludalf in no-tillage systems. Experiment 1 was set up in 2004 in the experimental area of UFSM, in Santa Maria (RS, Brazil). The treatments consisted of: control (without nutrient application) and application of pig slurry (PS), pig deep-litter (PL), cattle slurry (CS), and mineral fertilizers (NPK). The rates were determined to meet the N crop requirements of no-tillage black oat and maize, grown in the 2010/2011 growing season. The soil solution was collected after each event (rain + runoff or leaching) and the soluble, particulate and total P contents were measured. In November 2008, soil was collected in 2 cm intervals to a depth of 20 cm, in 5 cm intervals to a depth of 40 cm, and in 10 cm intervals to a depth of 70 cm. The soil was dried and ground, and P determined after extraction by anion exchange resin (AER). In experiment 2, samples collected from the Typic Hapludalf near experiment 1 were incubated for 20, 35, 58, 73 and 123 days after applying the following treatments: soil, soil + PS, soil + PL, soil + CS and soil + NPK. Thereafter, the soil was sampled and P was analyzed by AER. The applications of nutrient sources over the years led to an increase in available P and its migration in the soil profile. This led to P transfer via surface runoff and leaching, with the largest transfer being observed in PS and PL treatments, in which most P was applied. The soil available P and P transfer via surface runoff were correlated with the amounts applied, regardless of the P source. However, P transfer by leaching was not correlated with the applied nutrient amount, but rather with the solution amount leached in the soil profile.

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BACKGROUND: Deep hypothermia has been associated with an increased incidence of postoperative neurologic dysfunction after cardiac surgery in children. Recent studies suggest an excitotoxic mechanism involving overstimulation of glutamate receptors. Extracellular glutamate uptake occurs primarily by astrocytes. Astrocytes also store glycogen, which may be used to sustain the energy-consuming glutamate uptake. Extracellular glutamate and glycogen content were studied during temperature changes mimicking cardiopulmonary bypass in vivo. METHODS: Primary cultures of cerebral cortical astrocytes were used in a specially designed incubator allowing continuous changes of temperature and ambient gas concentrations. The sequence of events was as follows: normothermia, rapid cooling (2.8 degrees C/min) followed by 60 min of deep hypothermia (15 degrees C), followed by rewarming (3.0 degrees C/min) and subsequent 5 h of mild hyperthermia (38.5 degrees C). Two different conditions of oxygenation were studied: (1) normoxia (25% O2, 70% N2, 5% CO2); or (2) hyperoxia (95% O2, 5% CO2). The extracellular glutamate concentrations and intracellular glycogen levels were measured at nine time points. RESULTS: One hundred sixty-two cultures were studied in four independent experiments. The extracellular concentration of glutamate in the normoxic group increased significantly from 35+/-10 nM/mg protein at baseline up to 100+/-15 nM/mg protein at the end of 5 h of mild hyperthermia (P < 0.05). In contrast, extracellular glutamate levels did not vary from control in the hyperoxic group. Glycogen levels decreased significantly from 260+/-85 nM/mg protein at baseline to < 25+/-5 nM/mg protein at the end of 5 h in the normoxic group (P < 0.05) but returned to control levels after rewarming in the hyperoxic group. No morphologic changes were observed in either group. CONCLUSION: The extracellular concentration of glutamate increases, whereas the intracellular glycogen content decreases when astrocytes are exposed to a sequence of deep hypothermia and rewarming. This effect of hypothermia is prevented when astrocytes are exposed to hyperoxic conditions.

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In the previous Comment, Forker and co-workers claim that perturbed angular correlation (PAC) data leave no alternative to the conclusion that the spontaneous magnetization of PrCo2 and NdCo2 undergoes a discontinuous, first-order phase transition at TC. We show here that their claim is in clear contradiction with a wealth of experimental evidence, including our own. Finally, we propose a possible origin for the disagreement between their interpretation of the PAC results and the literature on this subject.

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Modern agriculture techniques have a great impact on crops and soil quality, especially by the increased machinery traffic and weight. Several devices have been developed for determining soil properties in the field, aimed at managing compacted areas. Penetrometry is a widely used technique; however, there are several types of penetrometers, which have different action modes that can affect the soil resistance measurement. The objective of this study was to compare the functionality of two penetrometry methods (manual and automated mode) in the field identification of compacted, highly mechanized sugarcane areas, considering the influence of soil water volumetric content (θ) on soil penetration resistance (PR). Three sugarcane fields on a Rhodic Eutrudrox were chosen, under a sequence of harvest systems: one manual harvest (1ManH), one mechanized harvest (1MH) and three mechanized harvests (3MH). The different degrees of mechanization were associated to cumulative compaction processes. An electronic penetrometer was used on PR measurements, so that the rod was introduced into the soil by hand (Manual) and by an electromechanical motor (Auto). The θ was measured in the field with a soil moisture sensor. Results showed an effect of θ on PR measurements and that regression models must be used to correct data before comparing harvesting systems. The rod introduction modes resulted in different mean PR values, where the "Manual" overestimated PR compared to the "Auto" mode at low θ.

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Visible and near infrared (vis-NIR) spectroscopy is widely used to detect soil properties. The objective of this study is to evaluate the combined effect of moisture content (MC) and the modeling algorithm on prediction of soil organic carbon (SOC) and pH. Partial least squares (PLS) and the Artificial neural network (ANN) for modeling of SOC and pH at different MC levels were compared in terms of efficiency in prediction of regression. A total of 270 soil samples were used. Before spectral measurement, dry soil samples were weighed to determine the amount of water to be added by weight to achieve the specified gravimetric MC levels of 5, 10, 15, 20, and 25 %. A fiber-optic vis-NIR spectrophotometer (350-2500 nm) was used to measure spectra of soil samples in the diffuse reflectance mode. Spectra preprocessing and PLS regression were carried using Unscrambler® software. Statistica® software was used for ANN modeling. The best prediction result for SOC was obtained using the ANN (RMSEP = 0.82 % and RPD = 4.23) for soil samples with 25 % MC. The best prediction results for pH were obtained with PLS for dry soil samples (RMSEP = 0.65 % and RPD = 1.68) and soil samples with 10 % MC (RMSEP = 0.61 % and RPD = 1.71). Whereas the ANN showed better performance for SOC prediction at all MC levels, PLS showed better predictive accuracy of pH at all MC levels except for 25 % MC. Therefore, based on the data set used in the current study, the ANN is recommended for the analyses of SOC at all MC levels, whereas PLS is recommended for the analysis of pH at MC levels below 20 %.

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Naive scale invariance is not a true property of natural images. Natural monochrome images possess a much richer geometrical structure, which is particularly well described in terms of multiscaling relations. This means that the pixels of a given image can be decomposed into sets, the fractal components of the image, with well-defined scaling exponents [Turiel and Parga, Neural Comput. 12, 763 (2000)]. Here it is shown that hyperspectral representations of natural scenes also exhibit multiscaling properties, observing the same kind of behavior. A precise measure of the informational relevance of the fractal components is also given, and it is shown that there are important differences between the intrinsically redundant red-green-blue system and the decorrelated one defined in Ruderman, Cronin, and Chiao [J. Opt. Soc. Am. A 15, 2036 (1998)].

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Melon is one of the most demanding cucurbits regarding fertilization, requiring knowledge of soils, crop nutritional requirements, time of application, and nutrient use efficiency for proper fertilization. Developing support systems for decision-making for fertilization that considers these variables in nutrient requirement and supply is necessary. The objective of this study was parameterization of a fertilizer recommendation system for melon (Ferticalc-melon) based on nutritional balance. To estimate fertilizer recommendation, the system considers the requirement subsystem (REQ), which includes the demand for nutrients by the plant, and the supply subsystem (SUP), which corresponds to the supply of nutrients through the soil and irrigation water. After determining the REQtotal and SUPtotal, the system calculates the nutrient balances for N, P, K, Ca, Mg, and S, recommending fertilizer application if the balance is negative (SUP < REQ), but not if the balance is positive or zero (SUP ≥ REQ). Simulations were made for different melon types (Yellow, Cantaloupe, Galia and Piel-de-sapo), with expected yield of 45 t ha-1. The system estimated that Galia type was the least demanding in P, while Piel-de-sapo was the most demanding. Cantaloupe was the least demanding for N and Ca, while the Yellow type required less K, Mg, and S. As compared to other fertilizer recommendation methods adopted in Brazil, the Ferticalc system was more dynamic and flexible. Although the system has shown satisfactory results, it needs to be evaluated under field conditions to improve its recommendations.

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The application of pig slurry rates and plant cultivation can modify the soil phosphorus (P) content and distribution of chemical species in solution. The purpose of this study was to evaluate the total P, available P and P in solution, and the distribution of chemical P species in solution, in a soil under longstanding pig slurry applications and crop cultivation. The study was carried out in soil columns with undisturbed structure, collected in an experiment conducted for eight years in the experimental unit of the Universidade Federal de Santa Maria (UFSM), Santa Maria (RS). The soil was an Argissolo Vermelho distrófico arênico (Typic Hapludalf), subjected to applications of 0, 20, 40, and 80 m3 ha-1 pig slurry. Soil samples were collected from the layers 0-5, 5-10, 10-20, 20-30, 30-40, and 40-60 cm, before and after black oat and maize grown in a greenhouse, for the determination of available P, total P and P in the soil solution. In the solution, the concentration of the major cations, anions, dissolved organic carbon (DOC), and pH were determined. The distribution of chemical P species was determined by software Visual Minteq. The 21 pig slurry applications increased the total P content in the soil to a depth of 40 cm, and the P extracted by Mehlich-1 and from the solution to a depth of 30 cm. Successive applications of pig slurry changed the balance between the solid and liquid phases in the surface soil layers, increasing the proportion of the total amount of P present in the soil solution, aside from changing the chemical species in the solution, reducing the percentage complexed with Al and increasing the one complexed with Ca and Mg in the layers 0-5 and 5-10 cm. Black oat and maize cultivation increased pH in the solution, thereby increasing the proportion of HPO42- and reducing H2PO4- species.

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ABSTRACT Diffuse reflectance spectroscopy (DRS) is a fast and cheap alternative for soil clay, but needs further investigation to assess the scope of application. The purpose of the study was to develop a linear regression model to predict clay content from DRS data, to classify the soils into three textural classes, similar to those defined by a regulation of the Brazilian Ministry of Agriculture, Livestock and Food Supply. The DRS data of 412 soil samples, from the 0.0-0.5 m layer, from different locations in the state of Rio Grande do Sul, Brazil, were measured at wavelengths of 350 to 2,500 nm in the laboratory. The fitting of the linear regression model developed to predict soil clay content from the DRS data was based on a R2 value of 0.74 and 0.75, with a RMSE of 7.82 and 8.51 % for the calibration and validation sets, respectively. Soil texture classification had an overall accuracy of 79.0 % (calibration) and 80.9 % (validation). The heterogeneity of soil samples affected the performance of the prediction models. Future studies should consider a previous classification of soil samples in different groups by soil type, parent material and/or sampling region.

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This investigation was initiated to determine the causes of a rutting problem that occurred on Interstate 80 in Adair County. 1-80 from Iowa 25 to the Dallas County line was opened to traffic in November, 1960. The original pavement consisted of 4-1/2" of asphalt cement concrete over 12" of rolled stone base and 12" of granular subbase. A 5-1/2" overlay of asphalt cement concrete was placed in 1964. In 1970-1972, the roadway was resurfaced with 3" of asphalt cement concrete. In 1982, an asphalt cement concrete inlay, designed for a 10-year life, was placed in the eastbound lane. The mix designs for all courses met or exceeded all current criteria being used to formulate job mixes. Field construction reports indicate .that asphalt usage, densities, field voids and filler bitumen determinations were well within specification limits on a very consistent basis. Field laboratory reports indicate that laboratory voids for the base courses were within the prescribed limits for the base course and below the prescribed limits for the surface course. Instructional memorandums do indicate that extreme caution should be exercised when the voids are at or near the lower limits and traffic is not minimal. There is also a provision that provides for field voids controlling when there is a conflict between laboratory voids and field voids. It appears that contract documents do not adequately address the directions that must be taken when this conflict arises since it can readily be shown that laboratory voids must be in the very low or dangerous range if field voids are to be kept below the maximum limit under the current density specifications. A rut depth survey of January, 1983, identified little or no rutting on this section of roadway. Cross sections obtained in October, 1983, identified rutting which ranged from 0 to 0.9" with a general trend of the rutting to increase from a value of approximately 0.3" at MP 88 to a rut depth of 0.7" at MP 98. No areas of significant rutting were identified in the inside lane. Structural evaluation with the Road Rater indicated adequate structural capacity and also indicated that the longitudinal subdrains were functioning properly to provide adequate soil support values. Two pavement sections taken from the driving lane indicated very little distortion in the lower 7" base course. Essentially all of the distortion had occurred in the upper 2" base course and the 1..;1/2" surface course. Analysis of cores taken from this section of Interstate 80 indicated very little densification of either the surface or the upper or lower base courses. The asphalt cement content of both the Type B base courses and the Type A surface course were substantially higher than the intended asphalt cement content. The only explanation for this is that the salvaged material contained a greater percent of asphalt cement than initial extractions indicated. The penetration and viscosity of the blend of new asphalt cement and the asphalt cement recovered from the salvaged material were relatively close to that intended for this project. The 1983 ambient temperatures were extremely high from June 20 through September 10. The rutting is a result of a combination of adverse factors including, (1) high asphalt content, (2) the difference between laboratory and field voids, (3) lack of intermediate sized crushed particles, (4) high ambient temperatures. The high asphalt content in the 2" upper base course produced an asphalt concrete mix that did not exhibit satisfactory resistance to deformation from heavy loading. The majority of the rutting resulted from distortion of the 2" upper base lift. Heater planing is recommended as an interim corrective action. Further recommendation is to design for a 20-year alternative by removing 2-1/2" of material from the driving lane by milling and replacing with 2-1/2" of asphalt concrete with improved stability. This would be .followed by placing 1-1/2" of high quality resurfacing on the entire roadway. Other recommendations include improved density and stability requirements for asphalt concrete on high traffic roadways.

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This research investigated the effects of changing the cementitious content required at a given water-to-cement ratio (w/c) on workability, strength, and durability of a concrete mixture. An experimental program was conducted in which 64 concrete mixtures with w/c ranging between 0.35 and 0.50, cementitious content ranging from 400 to 700 per cubic yard (pcy), and containing four different supplementary cementitious material (SCM) combinations were tested. The fine-aggregate to total-aggregate ratio was fixed at 0.42 and the void content of combined aggregates was held constant for all the mixtures. Fresh (i.e., slump, unit weight, air content, and setting time) and hardened properties (i.e., compressive strength, chloride penetrability, and air permeability) were determined. The hypothesis behind this study is that when other parameters are kept constant, concrete properties such as strength, chloride penetration, and air permeability will not be improved significantly by increasing the cement after a minimum cement content is used. The study found that about 1.5 times more paste is required than voids between the aggregates to obtain a minimum workability. Below this value, water-reducing admixtures are of no benefit. Increasing paste thereafter increased workability. In addition, for a given w/c, increasing cementitious content does not significantly improve compressive strength once the critical minimum has been provided. The critical value is about twice the voids content of the aggregate system. Finally, for a given w/c, increasing paste content increases chloride penetrability and air permeability.