University of the Llanos

This paper presents an abstract framework for the analysis of a numerical scheme designed for degenerate parabolic equations with time-dependent operators. We derive quasi-optimal error estimates for the approximation and establish sufficient conditions that guarantee the existence of a unique numerical solution. In our analysis, we use a finite element method for the spatial discretization and an implicit Euler scheme for the temporal discretization. Furthermore, applications with different operator choices are considered to illustrate the abstract theory. Finally, numerical experiments are carried out in order to validate the performance of the method and to corroborate our theoretical results.

Freshwater ecosystem pollution has motivated an extensive list of studies due to deleterious impacts becoming a threat to aquatic organisms that inhabit these environments. This is the first approach to water pollution impact derived from human activities on native ichthyofauna in the Garagoa river basin in Boyacá (Colombian Andes). Therefore, the aim of the present study was to evaluate the occurrence of mercury and arsenic in catfishes and armored catfishes from the Garagoa River basin and the presence of hepatic alterations and genotoxicity in peripheral blood. Biomarkers of effect were analyzed in fishes caught in eight tributaries from Garagoa river basin. The increased presence of lesions in the hepatic architecture and nuclear abnormalities in peripheral blood erythrocytes in Dolichancistrus fuesslii, Chaetostoma joropo, Astroblepus latidens and Trichomycterus cf. knerii individuals could be associated with exposure of pollutants. The tissue alterations observed compromise the fish health, due to the biotransformation processes of xenobiotics such as mercury and arsenic and probably other contaminants. We need to increase surveillance in the Garagoa River to ensure ecological health, recognize hematological and tissue effects in native fishes, and develop effective monitoring strategies to mitigate sources of pollution.

This study examines the impact of learning style and study habits alignment on the academic success of engineering students. Over a 16-week semester, 72 students from the Process Engineering and Electronic Engineering programs at Universidad de Los Llanos participated in this study. They completed the Learning Styles Index questionnaire on the first day of class, and each week, teaching methods and class activities were aligned with one of the four learning dimensions of the Felder-Silverman Learning Styles Model. Lesson 1 focused on one side of the learning dimension, lesson 2 on the opposite side, and the tutorial session incorporated both. Quizzes and engagement surveys assessed short-term academic performance, while midterm and final exam results measured long-term performance. Paired t-tests, Cohen's effect size, and two-way ANOVA showed that aligning teaching methods with learning styles improved short-term exam scores and engagement. However, multiple regression analysis indicated that study habits (specifically, time spent studying, frequency, and scores on a custom-developed study quality survey) were much stronger predictors of midterm and final exam performance. Several machine learning models, including Random Forest and Voting Ensemble, were tested to predict academic outcomes using study behavior data. Voting Ensemble was found to be the strongest model, explaining 83% of the variance in final exam scores, with a mean absolute error of 3.18. Our findings suggest that while learning style alignment improves short-term engagement and comprehension, effective study habits and time management play a more important role in long-term academic success.

Los microhábitats son subdivisiones finas del hábitat donde a menudo ocurre la mayor diferenciación en el uso de recursos por las comunidades de anuros. En esta investigación analizamos el uso de microhábitat y el solapamiento de nicho de cuatro especies de ranas hylidas de estanques piscícolas en la Universidad de los Llanos en Meta, Colombia. Durante 12 salidas nocturnas de muestreo en un período de cuatro meses, registramos tres variables de microhábitat utilizadas por las ranas: tipo de sustrato, posición vertical y tipo de vegetación. A partir de estos datos, calculamos los índices de amplitud de nicho y de solapamiento de nicho comunitario basados en 31–79 observaciones para cada especie. Las ranas frecuentaron los sustratos hoja y rama, las posiciones verticales baja y media, y la vegetación arbustiva y herbácea. Dendropsophus mathiassoni, Dendropsophus minutus y Scinax rostratus tuvieron amplitudes de nicho bajas para las tres variables de microhábitat medidos, mientras que Boana platanera tuvo una amplitud de nicho intermedia para el uso de sustrato y amplitudes altas para la posición vertical y el tipo de vegetación utilizado. El índice de solapamiento de nicho comunitario probado contra modelos nulos, permitió evidenciar que las especies de hylidos presentan una distribución aleatoria en el uso de recursos ecológicos, lo que indica la ausencia de mecanismos ecológicos que influyan en el solapamiento de nicho en la comunidad.

It is challenging to accurately analyze and monitor the environmental quality of soils globally because data on precise baseline concentrations are lacking. Colombia is a country where baseline data is practically missing. This study focused on the highly weathered soils of the Piedmont Llanero (hyperhumid equatorial environment). The baseline vanadium (V) concentration was assessed and the possible influence of agricultural land use was examined. The results showed clear variability in V concentrations across land uses. The V content in soils in the natural environment was 5.8-76.7 mg kg −1 with a mean of 31.5 mg kg −1 and in agricultural soils was 20.7-88.6 mg kg −1 with a mean of 51.8 mg kg −1. The overall average was 41.7 mg kg −1 with a range of 5.8-88.6 mg kg −1 , which are widely scattered values. The V concentration was compared to the world average values and was within normal ranges versus other areas. The calculated reference value (RV) for V was 38.4 mg kg −1. Based on the contamination factor, contamination was moderate (1.1) in the whole area. No contamination was detected when analyzed with I-geo (−0.6). These findings clearly suggest that V was moderately contaminating in cultivated soils, but posed no ecological risks in the study area. No simple relation was found between V concentrations and investigated litho-and pedogenic factors. This work contains valuable information for not only legislative purposes but also for soil quality RVs in a hyperhumid equatorial climate.

To evaluate the impact of Saccharomyces cerevisiae (SC) supplementation on pancreatic islet areas, alpha and beta cell populations, blood glucose levels, and lipid profiles in broilers, broilers were randomly assigned to two groups: a control group (T1) without SC and a treatment group (T2) supplemented with SC. Islet areas, alpha and beta cell counts, serum glucose and insulin levels, and lipid profiles were assessed. SC supplementation significantly decreased blood glucose levels compared to the control group. Additionally, HDL cholesterol levels were elevated in the SC-supplemented group. Although insulin levels remained unchanged, SC supplementation altered the correlation between pancreatic islet areas and alpha and beta cell populations, suggesting a potential influence on pancreatic islet function. Dietary supplementation with Saccharomyces cerevisiae can improve glycemic control and lipid profile in broilers. These findings highlight the potential benefits of using SC as a dietary additive in broiler production.

Quantifying and analyzing nitrous oxide (N2O) emissions from sugarcane-cultivated soils is a priority issue due to its potential role in climate change in the coming decades. However, understanding the impact of this crop on global N2O emissions is complicated by the variety of experimental conditions and methods used to quantify these emissions. This study aimed to determine the influence of experimental conditions and methodological approaches on quantifying of N2O emissions in soils used for sugarcane production. For this purpose, a meta-analysis of quantitative information on this topic, and published-online up to December 2020 was performed. The average daily N2O emission rate calculated in this research was higher than similar studies and the differences were attributed to methodological differences with these references. In addition, results showed that variables associated with sampling and gas concentration measurement had no significant effects on daily mean N2O emissions. The evaluation period, soil texture, and the management of synthetic N sources and application rates were the main variables affecting N2O emissions. Among the important sugarcane-producing countries United States and India had significantly higher daily mean N2O emission (4.5 ± 1.4 and 3.08 ± 0.08 mg N2O–N m−2 d−1, respectively) than the global average (1.98 ± 0.4 mg N2O–N m−2 d−1). High N2O emissions were widely documented in coarse or intermediate-texture soils. It is recommended that to reduce the uncertainty associated with the estimation of cumulative N2O emissions the monitoring of N2O emissions should include multiple complete growing seasons and include high sampling frequency around the main management practices. The strategies to reduce emissions should focus on the exploration of alternative N fertilizers to urea in sub-traditional doses for sugarcane areas with coarser textured soils. This work provides an important reference framework for the design and development of future research focused on the assessment of N2O mitigation options for sugarcane.

Our objective was to evaluate the effects of protein supplementation frequency and supplementation plans during gestation on productive performance and metabolic responses of grazing super-precocious Nellore heifers. Thirty-five pregnant Nellore heifers were used in a completely randomized design in a 2 × 2 factorial arrangement with an additional control group. The factors were the following: 1. Frequency of supplementation: (a) Daily (seven times per week), (b) Infrequent (three times per week); 2. Supplementation plans: (a) Constant, (b) Increasing. A control group with no supplementation was included. Two digestibility trials were carried out on the 40th and 130th experimental days. Productive performance and body composition were evaluated in the prepartum and postpartum periods. Blood samples were collected at −114, −113, −15, −14, +15, +30, and +45 days relative to calving for measuring metabolic status. Supplementation (daily and infrequent) increased the intake of total dry matter (DM) (p ≤ 0.004), average daily gain (p < 0.001), and body weight at calving (p = 0.008) at prepartum. However, frequency or supplementation plan did not alter (p > 0.17) the intake of total DM and forage DM. There was an effect (p ≤ 0.02) of the supplementation plan on subcutaneous thickness fat in the prepartum period and albumin and non-esterified fatty acid concentrations (p < 0.004) in the postpartum period. Nonetheless, frequency and supplementation plans did not affect (p ≥ 0.10) heifers’ productive performance during the postpartum period. In conclusion, protein supplementation frequency and supplementation plan during beef heifers’ gestation do not negatively impact their productive performance or metabolic responses.

This study aimed to investigate the effects of acid or alkali modification of isolated cassava starch (ICS) on its physicochemical properties. Acetic acid concentrations of 5%, 10%, and 20% v/v (0.87, 1.73, and 3.46 M, respectively) and calcium hydroxide concentrations of 0.15%, 0.20%, and 0.30% w/w (0.02, 0.025, and 0.04 M, respectively) were tested independently and compared with untreated isolated starch. The scanning electron microscope (SEM) shows starches with polyhedral and semispherical shapes; these modifications do not change the surface of the starch granules. Nanocrystals with orthorhombic crystal structure were extracted from ICS. Transmission electron microscopy (TEM) shows crystallites with a size (two‐dimensional) of 20 ± 5 nm in length and 10 ± 2 nm in width and reveals that this starch contains nanocrystals with orthorhombic crystal structure. The X‐ray patterns show that these nanocrystals are unaffected by acidic or alkaline treatments. The Ca⁺² and CH3COO⁻ ions do not interact with these nanocrystals. The alkaline treatment only affects the gelatinization temperature at a Ca(OH)2 concentration of 0.30%. Low concentrations of acidic and alkaline treatments affect the ability of cassava starch to absorb water and reduce the peak and final viscosity. The infrared spectra show that the modifications lead to C–H and C═C bond formations. ICS‐B 0.30 can modify the amorphous regions of the starch, and the acid treatment leads to acetylation, which was confirmed by the presence of an IR band at 1740 cm⁻¹.

The quantification of pollutant metabolites in fish bile is an efficient approach to xenobiotic pollution monitoring in freshwaters since these measurements directly address exposure. Fluorescence excitation-emission matrix spectroscopy (EEMS) has demonstrated to be a highly specific and cost-effective technique for polycyclic aromatic hydrocarbon (PAH) and PAH-metabolite identification and quantification. EEMS ability to quantify these compounds strongly depends on the intensity and variability of the bile baseline fluorescence (BBF). We found large differences in BBF among Aequidens metae (AME) individuals and of these with Piaractus orinoquensis (PIO). Moreover, BBF was large enough that solvent dilutions of over 1:400 were needed to avoid inner filter effects. We used parallel factor analysis (PARAFAC) to model the intra- and inter-species BBF variability. PARAFAC successfully decomposed the EEMS set into three fluorophores present in all samples, although in concentrations spreading over ~ 3 orders of magnitude. One of the factors was identified as tryptophan. Tryptophan and Factor 2 were covariant and much more abundant in AME than in PIO, while Factor 3 was ~ 6 times more abundant in PIO than in AME. Also, tryptophan was ~ 10x more abundant in AME specimens immediately caught in rivers than in their laboratory-adapted peers. The PARAFAC decomposition effectiveness was confirmed by the positive proportionality of scores to dilution ratios. A large inner filter indicates that Factor 2 is as strong a light absorber as tryptophan. Our results stress the need to include bile matrix variable components for the detection and quantification of pollutant metabolites using PARAFAC.

Introduction. Due to the cross-reactivity between SARS-CoV-2 and common human coronaviruses, previous infections with these viruses could contribute to serological or cellular cross-protection against severe COVID-19. However, protective immunity may not develop, or pre-existing immunity could increase COVID-19 severity. Objective. To determine the seroprevalence of IgG antibodies against HCoV-NL63 and HCoV-HKU1 and correlate previous exposure with COVID-19 signs in patients from Villavicencio. Materials and methods. A cross-sectional retrospective study was conducted. ELISA technique was used to search for IgG antibodies against HCoV-NL3 and HCoV-HKU1 in patients with positive RT-qPCR results for SARS-CoV-2. Patients were grouped according to COVID-19 clinical characteristics in four groups: group 1: asymptomatic (n = 23); group 2: hospitalized (n = 24); group 3: intensive care units (n = 24), and group 4: dead (n = 22). Results. The overall seroprevalence of IgG antibodies against HCoV was 74.2% (n = 69; 95% CI: 65.3-83.1), with 66.7% of HCoV-NL63 (n = 62; 95% CI: 57,1-76,2), and 25.8% of HCoV-HKU1 (n = 24; 95% CI: 16,9-34,7). Based on crosstab analysis, prior exposure to HCoV-NL63 was associated with protection against severe COVID-19 (p = 0.042; adjusted OR = 0.159; 95% CI: 0.027-0.938), and previous coinfection of HCoV-NL63 and HCoV-HKU1 was considered a positive association to severe COVID-19 (p = 0.048; adjusted OR = 16.704; 95% CI: 1.020 - 273.670). Conclusion. To our knowledge, this is the first study addressing seroprevalence of HCoV IgG antibodies in Colombia and Latin America. Previous exposure to HCoV-NL63 could protect against severe COVID-19, whereas patients with underlying HCoV-NL63 and HCoV-HKU1 coinfection could be hospitalized with severe signs of COVID-19.

Background: Reading nutritional labelling helps consumers select healthier food, thereby benefitting their oral health. The purpose of this study was to describe the knowledge, attitudes, and practices (KAPs) of parents and carers of children and preteens, associated with reading nutritional labelling, selecting sweetened ultra-processed foods, and their impact on oral health. Materials and Methods: This was a descriptive cross-sectional study in which a validated questionnaire was administered to 298 parents and caregivers of children aged 1–12 years from different districts in Villavicencio, Colombia. Participants’ scores, based on the number of correct answers, were used to classify their level of KAP as low, medium, or high. In addition, the frequency of responses, the KAP levels, and the median scores were analysed. Finally, associations were determined using the chi-square test. Results: Most participants reached a medium level in terms of knowledge (41.6%) and attitudes (49.3%) and a low level in terms of practices (43.3%). An association was found between participants’ level of KAPs and their socioeconomic and educational level (p < 0.05). Conclusions: The study findings reveal inadequate KAPs associated with nutritional labelling, adequate food selection, and the importance of oral health.

Common bean ( Phaseolus vulgaris L.) is the most important legume used for direct human consumption in Latin America, with an increasing expansion of cultivated areas in recent years. Here, we report the first occurrence of Conotrachelus quadrilineatus Champion, 1904 (Coleoptera: Curculionidae: Molytinae) feeding on bean in South America. Larvae and adults of C. quadrilineatus were observed during the first half of 2022, severely affecting the plantations of 20 bean farmers in the municipality of Garcia-Rovira, Santander Colombia. It is necessary to describe and quantify the damage of C. quadrilineatus in bean crops, as well as to study its bioecology.