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1
artículo
While it is true that vaccines generate immunity with a high degree of effectiveness and that in Peru, a certain time was spent initiating the COVID-19 disease, a vaccination process that was developed logistically. The objective was to obtain the mathematical model of the COVID-19 vaccination process in Peru, to estimate the number of people vaccinated, the critical time for which the estimated rate of vaccinated people has been the highest value, and to specify the date on which the highest number of people vaccinated has occurred. The methodology was based on determining the form of dispersion of the vaccination process, this being a logistic distribution and considering that a mathematical model is a mathematical description, by means of a function of a real-world phenomenon, such as the number of people vaccinated against the COVID-19 disease. The model presented a correlation coeff...
2
artículo
This research presents a theoretical review of the structure and applica-tion of long memory nature models that combine characteristics of the fractionally integrated processes with the classic GARCH models, thus obtaining the autoregres-sive models with fractionally integrated conditioned heterocedasticity (FIGARCH) which Through the cumulative response impulse function, I can quantify the degree of persistence of the impact of innovation on the function of conditioned variance, that is, the element of persistence in a chaotic series very sensitive to changes in initial conditions associated with fractional Brownian motion. For this application, the exchange rate variable was used, and by means of long memory time series mo-dels, the persistence of the existing effect on the volatility of said series could be analyzed.
3
artículo
This research presents a theoretical review of the structure and applica-tion of long memory nature models that combine characteristics of the fractionally integrated processes with the classic GARCH models, thus obtaining the autoregres-sive models with fractionally integrated conditioned heterocedasticity (FIGARCH) which Through the cumulative response impulse function, I can quantify the degree of persistence of the impact of innovation on the function of conditioned variance, that is, the element of persistence in a chaotic series very sensitive to changes in initial conditions associated with fractional Brownian motion. For this application, the exchange rate variable was used, and by means of long memory time series mo-dels, the persistence of the existing effect on the volatility of said series could be analyzed.
4
artículo
Publicado 2022
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Gaussian processes that can be decomposed into a smooth mean function and a stationary autocorrelated noise process are considered and a fully automatic nonparametric method to simultaneous estimation of mean and auto-covariance functions of such processes is developed. The proposed empirical Bayes approach is data-driven, numerically efficient, and allows for the construction of confidence sets for the mean function. Performance is demonstrated in simulations and real data analysis. The method is implemented in the R package eBsc.
5
artículo
Publicado 2022
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At the end of first quarter of 2020 it was seen in most countries statistics the beginning of an imminent second wave of pandemic. On January of 2021 it was seen in the data a rapid growth of new infections. In this paper, a geometry-based scheme is presented. In concrete the rectangle and trapezoid shapes are analyzed. From this, a relation between both geometries is extracted in terms of polynomial functions. The resulting characterization of a pandemic in terms of geometric variables is presented. Thus the present model is confronted with official data of USA and India. From the results of this paper, it is strongly believed that entropy might be behind of a global pandemic dynamics.
6
artículo
Publicado 2012
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This study estimates the economic costs of mining pollution on water resources for the years 2008 and 2009 based on the conceptual framework of Environmental Efficiency. This framework identifies such costs as the mining companies’ trade-off between increasing production that is saleable at market prices (desirable output) and reducing the environmental pollution that emerges from the production process (undesirable output). These economic costs were calculated from parametric and non parametric production possibility frontiers for 28 and 37 mining units in 2008 and 2009, respectively, which were under the purview of the National Campaign for Environmental Monitoring of Effluent and Water Resources, conducted by the Energy and Mining Investment Supervisory Agency (Osinergmin) in those years. The results show that the economic cost of mining pollution on water resources rose to U.S. $ 8...
7
artículo
Publicado 2013
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The application of different unit root statistics is by now a standard practice in empirical work. Even when it is a practical issue, these statistics have complex nonstandard distributions depending on functionals of certain stochastic processes, and their derivations represent a barrier even for many theoretical econometricians. These derivations are based on rigorous and fundamental statistical tools which are not (very) well known by standard econometricians. This paper aims to fill this gap by explaining in a simple way one of these fundamental tools: namely, the Functional Central Limit Theorem. To this end, this paper analyzes the foundations and applicability of two versions of the Functional Central Limit Theorem within the framework of a unit root with a structural break. Initial attention is focused on the probabilistic structure of the time series to be considered. Thereafter...
8
tesis de maestría
Publicado 2013
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The backscatter coefficient (BSC) is an intrinsic property that quantifies the amount of energy that is reflected by a material as function of the ultrasound wave frequency. BSCs have been proposed for decades for tissue characterization, along with quantitative ultrasound (QUS) parameters derived from BSCs that have been used to construct images that represent how these properties vary spatially. The availability of formulations based on weakly focusing conditions has resulted in a widespread use of large focal number transducers for BSC estimation. The use of highly focused transducers offers the possibility of improving the spatial resolution of BSC-based imaging. The model by Chen et al. [1] was developed for estimating BSCs using transducers of arbitrary focal number. However, to this date only preliminary experimental validation of this method has been performed. The goals of the p...
9
tesis de maestría
Publicado 2013
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The backscatter coefficient (BSC) is an intrinsic property that quantifies the amount of energy that is reflected by a material as function of the ultrasound wave frequency. BSCs have been proposed for decades for tissue characterization, along with quantitative ultrasound (QUS) parameters derived from BSCs that have been used to construct images that represent how these properties vary spatially. The availability of formulations based on weakly focusing conditions has resulted in a widespread use of large focal number transducers for BSC estimation. The use of highly focused transducers offers the possibility of improving the spatial resolution of BSC-based imaging. The model by Chen et al. [1] was developed for estimating BSCs using transducers of arbitrary focal number. However, to this date only preliminary experimental validation of this method has been performed. The goals of the p...
10
artículo
Publicado 2021
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This research focused on the synthesis of a functional alginate-based material via chemical modification processes with two steps: oxidation and reductive amination. In previous alginate functionalization with a target molecule such as cysteine, the starting material was purified and characterized by UV-Vis,1 H-NMR and HSQC. Additionally, the application of FT-IR techniques during each step of alginate functionalization was very useful, since new bands and spiked signals around the pyranose ring (1200–1000 cm−1) and anomeric region (1000–750 cm−1) region were identified by a second derivative. Additionally, the presence of C1-H1 of β-D-mannuronic acid residue as well as C1-H1 of α-L-guluronic acid residue was observed in the FT-IR spectra, including a band at 858 cm−1 with characteristics of the N-H moiety from cysteine. The possibility of attaching cysteine molecules to an a...
11
artículo
Estimation of nitrogen content in sugarcane based on vegetation indices derived from Sentinel-2 data
Publicado 2025
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Sugarcane occupies a large territorial scale in the world and is constantly searching for mechanisms to monitor nutrients in the crop production cycle, using non-destructive methods. The study aimed to estimate the nitrogen content in the sugarcane leaf was developed in the 2021/2022 harvest on two commercial fields of dryland cultivars (RB867515 = 50.75 ha) and (CVSP7870 = 48.56 ha) at the Serranópolis-Goiás mill, evaluating the efficiency of the biochemical vegetation indices Fraction of Absorbed Photosynthetically Active Radiation (fAPAR) and Canopy Chlorophyll Content (CCC) processed using the radiation transfer model RTM PROSAIL, compared to the Normalized Difference Vegetation Index (NDVI) and Green Normalized Difference Vegetation Index (GNDVI), processed using mathematical band ratio models. Both were based on a time series of Sentinel-2 data as input variables. The validation ...
12
artículo
Publicado 2013
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This paper explores the generation process of human capital in a dynamic perspective. In order to do so: a) characterizes the recent evolution of human capital, using as proxy the same results panel of participating countries in PISA; b) explores different specifications of the production function of human capital capable of generating dynamic patterns observed; and c) shows the ability of different specifications econometric literature usually employed to correctly detect the structure of the production function. The observed dynamics are different between countries, highlighting the relative stability in the results of most developed countries, evolution consistent with certain specific properties of the production function. Additionally, the paper identifies the problems in econometric specifications usually employed in the literature to estimate correctly the importance of dynamic fa...
13
artículo
Publicado 2023
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Sacha inchi (Plukenetia huayllabambana) oil was co-microencapsulated with natural antioxidant extracts (NAE), such as camu-camu (Myrciaria dubia (HBK) Mc Vaugh) fruit, Añil variety Andean potato (Solanum tuberosum andigenum, and elderberry fruit (Sambucus peruviana). Gum Arabic and the ternary combination of gum Arabic (GA) + maltodextrin (MD) + whey protein isolate (WPI) at different formulations were used as coating materials for the encapsulation process using spray-drying. The moisture content, particle size distribution and morphology, total phenolic content, antioxidant activity, fatty acid and sterol composition, oxidative stability, and shelf-life were evaluated. Co-microcapsules of sacha inchi (P. huayllabambana) oil with camu camu skin extract (CCSE) at 200 ppm encapsulated with GA + MD + WPI had the highest total polyphenol content (4239.80 µg GAE/g powder), antioxidant acti...
14
artículo
Publicado 2021
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The purpose of the present study was to construct a brief scale of psychological well-being in the university context, in a preliminary phase. For this purpose, 417 students from the faculty of education of a public university in Lima, of both sexes, aged between 17 and 35 years (M = 23, S.D. = 1.86), participated in the study. We worked with the topics of Mental Health (MH) and Family and Interpersonal Relations (FR). The method was instrumental, with a scale of 35 items and seven components, approved by five experts through Aiken's V statistic, with three evaluation criteria (V = .83, 1.00). The items went through different analysis processes in parameter estimations with the two-logistic parameter model (2LP) of the Item Response Theory (IRT), in contrast with indicators of the Classical Test Theory (CTT), from the Confirmatory Factor Analysis (CFA) and internal consistency measures. ...
15
artículo
Publicado 2025
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The relationship between executive functions (EF), creative personality, and academic performance in Argentine university students was examined. A total of 248 students (M = 22.97 years, SD = 4.43) from various Argentine provinces participated. The Adult Executive Functioning Inventory (ADEXI), the Cognitive Flexibility Scale, the Creative Behavior Scale (ECC), and the Creative Personality Scale (EPC) were used, along with academic performance data and sociodemographic information. Data were collected online through Google Forms and analyzed using Spearman correlations and mediation analysis with robust Maximum Likelihood estimator and Bootstrap. Cognitive flexibility exhibited the most robust correlation with grade point average (r = .281, p < .001), followed by working memory difficulties (r = -.234, p < .001). Creative personality correlated positively with grade point average (...
16
artículo
Mathematical modelling applied to batch milling (at experimental level), is a very important tool to simulate and predict the granulometric yield of a given treated ore; this means, for a given duration of milling operation, to obtain an estimate of the corresponding granulometric analysis, which can then be tested with real data later on, to verify the estimates. The model involves the selection and fracture functions depending on each mesh size in the ore distribution. This will allow the prediction of effective and reliable results, saving costs and more importantly, time, without the need to perform the milling process for each prediction of batch milling.
17
artículo
Mathematical modelling applied to batch milling (at experimental level), is a very important tool to simulate and predict the granulometric yield of a given treated ore; this means, for a given duration of milling operation, to obtain an estimate of the corresponding granulometric analysis, which can then be tested with real data later on, to verify the estimates. The model involves the selection and fracture functions depending on each mesh size in the ore distribution. This will allow the prediction of effective and reliable results, saving costs and more importantly, time, without the need to perform the milling process for each prediction of batch milling.
18
artículo
Publicado 2024
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Stochastic processes with the long-range dependency (LRD) property are fundamental to modeling data that exhibit slow power decay of the covariance function. Such behavior often appears in the analysis of financial data, telecommunications, and various natural phenomena. Thus, introducing new stochastic models and statistical methods that take the LRD into account is of great interest. Based on previous work, we introduce a new stochastic process called quadratic fractionally integrated moving average, that arises from the Quadratic Ornstein-Uhlenbeck Type (QOUT) process, proposed in the literature. We consider Lévy noises of finite second-order moments and use a construction based on a moving average stochastic process whose kernel is that of a QOUT process. Then, using Riemann-Liouville fractional integrals, we propose a fractionally integrated moving average process, for ...
19
artículo
Publicado 2022
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The real-time prediction and estimation of the spread of diseases, such as COVID-19 is of paramount importance as evidenced by the recent pandemic. This work is concerned with the distributed parameter estimation of the time–space propagation of such diseases using a diffusion–reaction epidemiological model of the susceptible–exposed–infected–recovered (SEIR) type. State estimation is based on continuous measurements of the number of infections and deaths per unit of time and of the host spatial domain. The observer design method is based on positive definite matrices to parameterize a class of Lyapunov functionals, in order to stabilize the estimation error dynamics. Thus, the stability conditions can be expressed as a set of matrix inequality constraints which can be solved numerically using sum of squares (SOS) and standard semi-definite programming (SDP) tools. The observer...
20
artículo
Measurements at the high-elevation Lamar Observatory in the Mantaro Valley (MV) in the Central Andes of Peru demonstrate a diurnal cycle of precipitation characterized by convective rainfall during the afternoon and nighttime stratiform rainfall with embedded convection. Wet season data (2016-2018) reveal long-duration (6-12 hr) shallow precipitating systems (LDPS) that produced about 17% of monsoon rainfall in 2016 and 2018 associated with El Nino and La Nina, respectively. The LPDS fraction of monsoon rainfall doubles to 35% with weekly recurrence in 2017 under El Nino Costero (coastal) conditions. LDPS occur under favorable moisture conditions dictated by the South America (SA) Low-Level Jet (SALLJ) and Cold Air Intrusions (CAIs). Backward trajectory analysis shows that precipitable water sustains >80% of seasonal precipitation and ties the LPDS to particular moisture source regions i...
