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1
artículo
The use of soil to implement several management systems, such as agriculture, livestock farming and agroforestry activities contribute to the depletion of the soil and the forest, reducing or increasing the levels of soil chemical attributes, such as calcium, magnesium, potassium, and phosphorus and increase or decrease of active (pH) or exchangeable (Aluminum) acidity. This study aimed to evaluate macronutrients (calcium - Ca2+, magnesium - Mg2+, potassium - K+ and phosphorus - P), as well as aluminum - Al3+ and soil pH, under use systems: agroforestry system - SAFs and pasture - PA, comparing them to Primary Forest - PF, in the Rosenthal community in Itacoatiara-AM, Brazil. The soils were sampled in layers 0-10 cm and 10-20 cm deep, with samples composed of six single samples each. The distribution of nutrient contents (Ca2+, Mg2+, K+ , and P) considering the 0-10 and 10-20 cm layers s...
2
artículo
The use of soil to implement several management systems, such as agriculture, livestock farming and agroforestry activities contribute to the depletion of the soil and the forest, reducing or increasing the levels of soil chemical attributes, such as calcium, magnesium, potassium, and phosphorus and increase or decrease of active (pH) or exchangeable (Aluminum) acidity. This study aimed to evaluate macronutrients (calcium - Ca2+, magnesium - Mg2+, potassium - K+ and phosphorus - P), as well as aluminum - Al3+ and soil pH, under use systems: agroforestry system - SAFs and pasture - PA, comparing them to Primary Forest - PF, in the Rosenthal community in Itacoatiara-AM, Brazil. The soils were sampled in layers 0-10 cm and 10-20 cm deep, with samples composed of six single samples each. The distribution of nutrient contents (Ca2+, Mg2+, K+ , and P) considering the 0-10 and 10-20 cm layers s...
3
artículo
In this work, we present the development of a numerical scheme based in finite differences for numerical approximation to the solution of a unidimensional coupled linear thermoelastic system. Development the necessaries conditions for stability, consistence and convergence of the numerical scheme. Based in Von Neumann's method, we get the conditions for conditional stability of this algorithm and based in an example we contrast computationally the approximate the approximate solution got, by the finite differences scheme with the analytic solution.
4
artículo
Publicado 2019
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Objective. To evaluate the dentin-resin bond´s resistance (DRBR) of the adhesives Optibond FL (OFL), Adper Single Bond 2 (ASB2) and Single Bond Universal (SBU) with its self-engraving possibility, in three different times of application. Methods. Experimental, comparative and crossectional in vitro study. We used nine human molars, obtaining 135 specimens of 1 mm2 approximately, forming nine study groups of 15 specimens for each group. The DRBR was measured through the Microtunsion test at a tensile force with an acceleration of 0.5mm/min until a fracture.The contrast of difference hypotheses was performed using the one-factor ANOVA test and Tukey's multiple comparisons, both at a confidence level of 95%. Results. After 10 seconds, significant differences were found between the OFL adhesive systems (25.78 ± 5.98 MPa) vs ASB2 (from 14.02 ± 3.06 MPa) at p<0.001, as well as between OF...
5
artículo
Publicado 2019
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Objective. To evaluate the dentin-resin bond´s resistance (DRBR) of the adhesives Optibond FL (OFL), Adper Single Bond 2 (ASB2) and Single Bond Universal (SBU) with its self-engraving possibility, in three different times of application. Methods. Experimental, comparative and crossectional in vitro study. We used nine human molars, obtaining 135 specimens of 1 mm2 approximately, forming nine study groups of 15 specimens for each group. The DRBR was measured through the Microtunsion test at a tensile force with an acceleration of 0.5mm/min until a fracture.The contrast of difference hypotheses was performed using the one-factor ANOVA test and Tukey's multiple comparisons, both at a confidence level of 95%. Results. After 10 seconds, significant differences were found between the OFL adhesive systems (25.78 ± 5.98 MPa) vs ASB2 (from 14.02 ± 3.06 MPa) at p<0.001, as well as between OF...
6
tesis de grado
Publicado 2024
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This research will address air pollution, a severe problem in all world cities, because it negatively affects people's health and deteriorates the ecosystem. NO2 is a gas linked to acid rain formation and various reactions with greenhouse gases. Meteorological variables influence the behavior of tropospheric NO2 concentration. During the period of confinement due to the COVID-19 pandemic, the concentration levels of pollutants dropped abruptly, which meant relief for the ecosystem. The application of Time Series models allows us to graphically identify the concentration of contaminants in various areas and make accurate forecasts to mitigate environmental problems in the future. The research analysis shows that the SARIMA model effectively forecasts the pollutant concentration in the San Borja and San Martin de Porres districts in Lima. Error tests such as R2, MAE, MAPE, MSE, and RSME, a...
7
artículo
Publicado 2023
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This research will address air pollution, a severe problem in all world cities, because it negatively affects people's health and deteriorates the ecosystem. NO2 is a gas linked to acid rain formation and various reactions with greenhouse gases. Meteorological variables influence the behavior of tropospheric NO2 concentration. During the period of confinement due to the COVID-19 pandemic, the concentration levels of pollutants dropped abruptly, which meant relief for the ecosystem. The application of Time Series models allows us to graphically identify the concentration of contaminants in various areas and make accurate forecasts to mitigate environmental problems in the future. The research analysis shows that the SARIMA model effectively forecasts the pollutant concentration in the San Borja and San Martin de Porres districts in Lima. Error tests such as R2, MAE, MAPE, MSE, and RSME, a...
8
artículo
Publicado 2022
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Avocado crop (Persea americana Mill.) is of great commercial importance due to its high profitability. However, it is being affected by various diseases and pests that affect yield and reduce fruit quality. The aim of this research was to develop methodologies for the evaluation of avocado plantations using different non-destructive technologies for rapid phenotyping and early detection of the incidence of diseases or damage due to stress in the stem. A plot of 0.7 ha. was evaluated, with a total of 44 individuals using Field-Map technology (dasometric and morphological characterization), RGB-multispectral images from Remotely Piloted Aircraft System (RPAS) (rapid phenotyping), while 15 individuals were evaluated using tomography (assessment of the internal state of the stem). The results with tomography indicated that there is a tree with wood rot of 14% with a lower acoustic speed with...
9
artículo
Education in media literacy in Ecuador has gained special relevance in the last decade. Both academics and researchers have pointed out that the country also needs to reduce the digital divide; and train students, teachers and all members of society in the use and consumption of traditional and digital media. Previous studies show that the level of media competency differs by type of education system, whether it is private, co-financed or public. This research determines if the type of education system (regular urban education, regular rural education, and flexible and distance education) is an influential factor in the generation of competencies. Through a questionnaire and the corresponding statistical analysis, it was concluded that students who attended the regular education system within the city demonstrated a higher level of media competency compared to the other participants of...
10
artículo
Education in media literacy in Ecuador has gained special relevance in the last decade. Both academics and researchers have pointed out that the country also needs to reduce the digital divide; and train students, teachers and all members of society in the use and consumption of traditional and digital media. Previous studies show that the level of media competency differs by type of education system, whether it is private, co-financed or public. This research determines if the type of education system (regular urban education, regular rural education, and flexible and distance education) is an influential factor in the generation of competencies. Through a questionnaire and the corresponding statistical analysis, it was concluded that students who attended the regular education system within the city demonstrated a higher level of media competency compared to the other participants of...
11
artículo
Publicado 2016
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This study investigated the influence of temperature on the color development of melanoidins formed from a single combination of glucose with amino acid. The selected amino acid, commonly found in apple juice and highly reactive in the Maillard reaction, were asparagine (Asn), aspartic acid (Asp) and glutamic acid (Glu). For this, the color development was evaluated by measuring browning at 420 nm and color measurements by spectrophotometry and colorimetry methods. The effect of temperature on the color intensity, the absorption of melanoidins were also measured at different wavelengths (280, 325, 405). The value of melanoidins formed from all model systems was located on a dominant wavelength of 325 nm, the ultra violet zone of the diagram. A first-order kinetic model was applied to L* and the evolution of color difference ΔE*. In addition, a*, b* values, significantly differences were...
12
artículo
Publicado 2016
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This study investigated the influence of temperature on the color development of melanoidins formed from a single combination of glucose with amino acid. The selected amino acid, commonly found in apple juice and highly reactive in the Maillard reaction, were asparagine (Asn), aspartic acid (Asp) and glutamic acid (Glu). For this, the color development was evaluated by measuring browning at 420 nm and color measurements by spectrophotometry and colorimetry methods. The effect of temperature on the color intensity, the absorption of melanoidins were also measured at different wavelengths (280, 325, 405). The value of melanoidins formed from all model systems was located on a dominant wavelength of 325 nm, the ultra violet zone of the diagram. A first-order kinetic model was applied to L* and the evolution of color difference ΔE*. In addition, a*, b* values, significantly differences were...
13
artículo
Publicado 2019
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Purpose. In this study, three models were empirically compared, the DeLone and McLean model, the Seddon model and the Modified Seddon model, by measuring the impact of a business intelligence system (BIS) in companies in Peru. After that, the mediators and dependent constructs were analysed to determine if they were behaving properly (a good level of variance explanation and significant relations with others constructs). The study used a sample of 104 users of the BIS, from companies in several important economic sectors, in a quasi-voluntary context and with six constructs: information quality, system quality, service quality, system dependence (system use), user satisfaction and perceived usefulness (individual impact). Design/methodology/approach. To interpret the results, the authors used structural equations. The idea was to look for the best fit and explanations for the outcomes. T...
14
artículo
Publicado 2019
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Purpose – In this study three models were empirically compared the DeLone and McLean model the Seddon model and the Modified Seddon model by measuring the impact of a business intelligence system (BIS) in companies in Peru. After that the mediators and dependent constructs were analysed todetermine if they were behaving properly (a good level of variance explanation and significant relations with others constructs). The study used a sample of 104 users of the BIS from companies in several important economic sectors in a quasi-voluntary context and with six constructs: information quality system quality service quality system dependence (system use) user satisfaction and perceived usefulness (individual impact). Design/methodology/approach – To interpret the results the authors used structural equations. The idea was to look for the best fit and explanations for the outcomes. The main...
15
artículo
Publicado 2003
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It was studied the structure of the values system of senior high schools students belonging to different socio-economic levels using Schwartz Theory as a framework. The participants were 1197 students sampled on a stratified probabilistic way, belonging to all school districts (USES) of Lima, Peru. The results of the psychometric analysis allowed to obtain the validity content index, the construct validity and the reliability index of the Schwartz Values Questionnaire (PVQ). The results showed that the scores of the students of the PVQ reached a normal distribution. The comparative analysis of the socioeconomic levels indicated that values of tradition and security prevail in low socio-economic students. The value of power prevails in students of middle socioeconomic level and the benevolence value prevails in the high socio-economic level. The values of self direccion, hedonism and achi...
16
artículo
Publicado 2021
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The present study was carried out at the confluence of the Baños, Minascocha and Quilla micro-basins; which belongs to the upper part of the Chancay-Huaral basin, in order to identify the areas of greatest vulnerability to high intensity rainfall phenomena (floods). For the modeling of this section, the flows obtained by means of the SWAT software were used. The flood simulation was carried out using the IBER V2.5 software, which is free software, which is used to simulate floods in shallow waters, that is, shallow waters. The files used were satellite images, DEM files, maximum flows. The Geographic Information Systems were also used: ArcGis 10.5, QGIS 3.8.2, SASPLANET, GLOBALMAPER. The mathematical basis was the two-dimensional equations of St. Venant, which incorporates the turbulence and friction of the flow. The results are shown in three strategic points at the exit of the headwat...
17
artículo
Publicado 2025
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This study addressed multi-product optimization in Cedrelinga cateniformis plantations in the Peruvian Amazon, aiming to maximize volumetric yields of logs and sawn lumber. Data from seven plantations of different ages and types, established on degraded land, were analyzed by using ten stem profile models to predict taper and optimize wood use. In addition, the structure of each plantation was evaluated using diameter distributions and height–diameter ratios; log and sawn timber production was optimized using SigmaE 2.0 software. The Garay model proved most effective, providing high predictive accuracy (adjusted R2 values up to 0.963) and biological realism. Marked differences in volumetric yield were observed between plantations: older and more widely spaced plantations produced higher timber volumes. Logs of optimal length (1.83–3.05 m) and larger dimension wood (e.g., 25.40 × 5.0...
18
artículo
Publicado 2025
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This study addressed multi-product optimization in Cedrelinga cateniformis plantations in the Peruvian Amazon, aiming to maximize volumetric yields of logs and sawn lumber. Data from seven plantations of different ages and types, established on degraded land, were analyzed by using ten stem profile models to predict taper and optimize wood use. In addition, the structure of each plantation was evaluated using diameter distributions and height–diameter ratios; log and sawn timber production was optimized using SigmaE 2.0 software. The Garay model proved most effective, providing high predictive accuracy (adjusted R2 values up to 0.963) and biological realism. Marked differences in volumetric yield were observed between plantations: older and more widely spaced plantations produced higher timber volumes. Logs of optimal length (1.83–3.05 m) and larger dimension wood (e.g., 25.40 × 5.0...
19
artículo
The application of the method to the study of radiographic vascular systems , by introducing radiopaque contrast substances within its light, has allowed a better understanding of anatomy , physiology, pathology and treatment. This at first was only targeting the venous and arterial systems ( 9) , in which surgical techniques boom reached through this process , aside perhaps lymphatic system due to technical difficulties for study. However, several attempts to try to visualize it, were made by subcutaneous or intraperitoneal introduction of contrast medium unsuccessfully temporarily abandoning this study. The first successes were obtained by Funaoka in 1930 who injected mercury and iodine salts within the lymphatic system ; was followed : Carvalho et al (1931 , 1934) , Toreff and Stoppani (1932 ) , Monville and Ané (1932 ) , Monke (1932 ) , Zolothrekin (1934 ) , Bennett and Shivas (1954...
20
artículo
Publicado 2025
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Introducción: La fase de retención en ortodoncia es esencial para mantener una oclusión corregida y prevenir la recidiva. Los retenedores transparentes, como Essix, son populares por su estética y precio accesible, pero su cobertura oclusal podría afectar los contactos anteriores y posteriores. Se han introducido versiones modificadas, como Occless Essix, para abordar estas preocupaciones. El objetivo del presente estudio fue comparar los cambios oclusales a lo largo del tiempo entre los retenedores Essix y Occless Essix utilizando el sistema T-Scan III. Materiales y métodos: Este estudio observacional analítico incluyó a 30 pacientes de ortodoncia tratados con Brackets MBT de 0,022 pulgadas y con extracciones de primeros premolares. Los pacientes se dividieron en dos grupos: uno con retenedores Essix y el otro con retenedores Occless Essix. Los contactos oclusales y sus intensid...
