University of Magdalena

Background Polyclads are a diverse group of marine free-living flatworms, with some species adapted to life in floating Sargassum mats. Recent studies suggest that, rather than being inherently pelagic, these flatworms should be classified as "clinging fauna", as they rely on floating substrates for habitat. New information This study documents, for the first time, the occurrence of Gnesioceros sargassicola and Chatziplana grubei in Sargassum along the Caribbean coast of Colombia. High-definition photographs of whole mounts and histological sections are provided for both species, along with detailed observations of their reproductive structures and 28S rDNA barcodes. These findings underscore the importance of exploring the fauna associated with Sargassum, contributing to a better understanding of polyclad distribution and raising the number of recorded species for Colombia to 26.

Background The Colombian Amazon is a region of remarkable biodiversity; however, several biological groups and their microhabitats remain poorly explored. Recent studies on soil ant diversity have provided new records and insights into their biology. Sampling techniques focused on exploring the soil interior (monoliths) and leaf litter have led to numerous new ant records for Colombia, as well as range expansions for many species previously known from other regions. New information Seven new species records are reported for the country and the distribution of 14 species is extended within the Department of Caquetá. These 21 records belong to five subfamilies and sixteen genera. For the first time, the genera Lenomyrmex (Fernández & Palacio), Myrmelachista (Roger), Oxyepoecus (Santschi) and Stegomyrmex (Emery) are recorded for the Colombian Amazon. Additionally, the first case of an ergatoid queen in Probolomyrmex kelleri (Oliveira & Feitosa) is documented. The northernmost records of Adelomyrmex striatus (Fernández) and Centromyrmex gigas (Forel) are also reported. Morphological observations, distribution data and images of all recorded species are included. The specimens were collected using the Tropical Soil Biology and Fertility (TSBF) and Winkler extraction methodologies. Furthermore, we present a checklist of ants from Caquetá, listing 321 species for the Department. Finally, we update the known ant diversity of Colombia, reporting a total of 1.280 species and 110 genera.

Spermatozoa were isolated from the seminal fluid using washing (wash), post-capacitation (POS), and swim-up (SU) techniques, followed by analysis through Surface-Enhanced Raman Spectroscopy (SERS). Density gradient and swim-up methods were applied to 35 semen samples to validate sperm quality. The resulting spectra showed notable variations at 408 cm⁻¹ (S–S stretch attributed to lysozyme) and 728 cm⁻¹ (associated with DNA alterations and methylation). These spectral markers were incorporated into partial least squares discriminant analysis (PLS-DA) models to distinguish among sperm populations prepared by different methods. One PLS-DA model differentiated wash from POS and SU, attaining 86% sensitivity and 91% accuracy. Another model distinguished between POS and SU, achieving 77% sensitivity and 74% accuracy. The combined use of SERS and multivariate analysis offers a promising alternative for assessing sperm quality, supported by motility assessments in 35 validated samples. This approach could enhance both the accuracy and efficiency of reproductive diagnostics.

This research examines how sustainability driven innovation and performance factors influence Nepali tourism-oriented small and medium enterprises (SMEs) operating with limited resources. It investigates the relationships between entrepreneurial leadership (EL), network orientation (NO), and entrepreneurial orientation (EO) by integrating the Resource-Based View (RBV) and Strategic Fit Theory. The study positions strategic flexibility (SF) as a moderator between EL and NO in shaping startup performance (SP), with technological innovation capabilities (TIC) acting as a mediator. EO plays a critical role in startup success, helping businesses overcome resource constraints and adopt sustainable practices such as green technologies and energy-saving methods. Through TIC, SMEs convert strategic orientations into competitive advantages, enabling them to address environmental and social sustainability challenges. In Nepal’s fragmented tourism sector, NO and EL do not directly affect organizational performance. However, the findings confirm that SF’s adaptive capability bridges EL and SP, underscoring adaptability as a key driver of sustainable growth. The research provides valuable insights into tourism and entrepreneurship in resource-scarce settings, highlighting adaptive strategies and technological advancement as critical for resilience and long-term sustainability. To explain how tourism SMEs in resource-constrained contexts, such as Nepal, achieve sustainable growth, the study integrates the Resource-Based View (RBV) and Strategic Fit Theory. The findings indicate that strategic flexibility (SF) and technological innovation capabilities (TIC) play significant mediating and moderating roles in linking entrepreneurial strategies to performance within fragile ecosystems. While previous research has primarily focused on advanced economies, this study demonstrates how SF and TIC mediate entrepreneurial strategies in fragile environments, offering practical implications for sustainable development in emerging markets.

This research aims to analyze the spatial and temporal distribution of residents and tourists in an urban context, assessing the risk of overtourism. To achieve this, a tourist city is conceptualized as a complex system and examined through an agent-based model (ABM), which simulates the interactions between heterogeneous agents and their environment. This computational approach enables the exploration of emergent spatial-temporal patterns and facilitates the interpretation of overtourism as a real-world experiment. The case study focuses on Santa Marta (Colombia), a well-established coastal destination currently facing potential entry into a phase of tourism decline if management remains reactive. Simulation results reveal a high risk of overtourism and illustrate the differentiated effects of two plausible management strategies at distinct spatial scales. Additionally, this study proposes a tourism intensity indicator, addressing the problem of overestimating tourism pressure in existing metrics. The proposed model offers a valuable decision-support tool for assessing impacts and designing proactive management measures in destinations experiencing rapid tourist growth across multiple spatial and temporal dimensions.

The main objective of this study was to evaluate the adsorption efficiency for removing nitrate and phosphate in an aqueous solution using adsorbents derived from rice husks and corn stalks. Five adsorbents were used: untreated rice husk (RH), raw corn stalk (CS), rice husk biochar (RHB), corn stalk biochar (CSB), and a rice husk biochar chemically modified with magnesium (RHB-Mg). The influence of operational variables (temperature, pH, adsorbent dose, and initial concentration) on individual and competitive adsorption of nitrate and phosphate was studied together with adsorption equilibrium and kinetics. The results showed that the best adsorbent was RHB-Mg, with maximum adsorption capacities of 111.10 mg/g for phosphate and 35.11 mg/g for nitrate, determined from Langmuir isotherm. Competitive adsorption of nitrate and phosphate was favorable using RHB-Mg, demonstrating that RHB-Mg could be used to remove these nutrients from wastewater.

Digital twin (DT) technology is transforming industrial automation by enabling the real-time simulation, predictive control, and optimization of complex systems. This study presents a DT-based kinematic control method designed for trajectory planning and execution in a 2RRR planar parallel manipulator. The framework utilizes ROS/Gazebo for virtual modeling and MATLAB’s Guide tool for a human–machine interface, establishing a synchronized virtual–physical environment. By dynamically bridging design and manufacturing phases, the DT model enhances operational insight through real-time data exchange and control flexibility. Statistical analyses, including the comparative hypothesis testing of angular positions and velocities with a 95% confidence level, validate the model’s precision, demonstrating a high degree of fidelity between the virtual model and the physical system. These findings confirm the DT’s reliability as an effective tool for trajectory programming, highlighting its potential in industrial robotics where adaptability and data-driven decision making are essential. This approach contributes to the evolving landscape of Industry 4.0 by supporting intelligent manufacturing systems with improved accuracy and efficiency.

This paper presents research results to improve energy efficiency in one of the crude oil heating furnaces at the “Hermanos Díaz” refinery in Santiago de Cuba, Cuba. It analyzes the main process’s variables and disturbances, and the multivariate dynamic behavior of the F-101 furnace temperature is characterized to evaluate different control strategies. In addition, the design of a linear regulation control law was implemented as a way to solve the limitations of the existing control of the furnace, to control the plant for the first time with a multivariable approach, demonstrating superior performance by guaranteeing decoupling between the variables, decreasing the overruns by 6%, and increasing the response speed of the system by more than 5 min. The comparison with results obtained with other control strategies allowed us to determine the better performance of the furnace by increasing its energy efficiency, evidencing the economic and environmental impact and obtaining as benefits a better dynamic behavior by reducing fuel oil consumption by 5%, equivalent to 0.74 m³/day, which reduces the operating costs of the plant, the temperature of the gasses by 2%, emissions of CO2 pollutant gas to the environment by between 3 and 5%, and increasing energy efficiency by 1.5%.

Introduction Colombian plants have a long history of use in traditional medicine and ethnopharmacology, particularly for treating stomach pain, digestive issues, diarrhea, and other gastrointestinal disorders. Recent studies have renewed interest in their potential therapeutic properties. Methods This study evaluated the giardicidal activity of 15 crude plant extracts native to the Colombian Amazon against Giardia lamblia (genotype A, strain WB/1267). The MTT colorimetric assay was used to determine the effectiveness of these extracts at a concentration of 500 μg/mL. Extracts showing significant activity were further analyzed to determine their half-maximal inhibitory concentration (IC50). The cell death mechanisms of Attalea butyracea were studied using flow cytometry, confocal microscopy, and transmission electron microscopy (TEM). Results Among the tested extracts, the Attalea butyracea fruit extract (P-2) exhibited the highest activity against WB/1267 (IC50 = 62.10 ± 6.57 μg/mL) and demonstrated giardicidal activity against GS/M (IC50 = 100.90 ± 3.40 μg/mL, genotype B) human infecting strains. These results prompted a detailed investigation into its mechanism of action using the WB/1267 strain as a model. At its IC50 concentration, P-2 primarily exerted its antiproliferative effect by induction of early apoptosis. A notable increase in late apoptosis and necrosis was observed at 2xIC50. Immunofluorescence assay (IFA) and confocal microscopy revealed chromatin condensation in treated trophozoites, while flow cytometry indicated G1/S cell cycle arrest. Furthermore, exposure to P-2 led to oxidative stress, evidenced by a significant increase in reactive oxygen species (ROS). The extract’s ability to disrupt various structural components of the parasite was confirmed through IFA and transmission electron microscopy. Interestingly, the P-2 extract effectively synergized with the first-line drug metronidazole against Giardia WB/1267 trophozoites. Discussion These findings underscore the therapeutic potential of Colombian plant extracts in treating giardiasis, particularly highlighting the novel giardicidal activity of Attalea butyracea fruit extract and its promise for further therapeutic development.

The lady beetles Tenuisvalvae notata and Cryptolaemus montrouzieri are important predators of mealybugs (Hemiptera: Pseudococcidae). Like the prey, these lady beetles produce wax filaments that cover their body during the larval stage. It has been hypothesized that lady beetle body wax chemical profiles are like their prey as i) a mechanism of camouflage, and ii) conveying protection to the lady beetle larvae against aphid-tending predatory ants. Here, we tested this hypothesis for the predators T. notata and C. montrouzieri and two mealybug prey species, Ferissia dasyrilii, and Planococcus citri. We assessed how prey species influence the predator’s cuticular chemistry throughout its development and evaluated the metabolic costs of wax production in both larvae and adults. Cuticular wax samples were analyzed using GC–MS and GC-FID, and metabolic costs were specifically evaluated in 4th instar larvae of both predator species. The larvae were subjected to body wax removal from 0 to 4 times. Results showed that predator body wax profiles are not like the chemical profile of prey body wax. There was a metabolic cost associated with wax removal; predators (male and female) showed a significant reduction in adult body weight when wax was removed. This suggests reallocation of energy to wax replacement instead of growth. In addition, we detected effects of wax removal on fecundity and egg viability. Our results do not support the hypothesis that predators mimic the cuticular wax composition of prey as a means of camouflage.

The species of the ant genus Nesomyrmex inhabiting the tropical dry forest (TDF) of Colombia are reviewed. Three new species of this genus, Nesomyrmex ikusp. nov., Nesomyrmex koninasp. nov., and Nesomyrmex xerophilussp. nov., are described based on worker caste. Nesomyrmex vargasi Longino, 2006 is recorded for the first time in South America, and Nesomyrmex antoniensis (Forel, 1912) is proposed as a junior synonym of Nesomyrmex asper (Mayr, 1887). A worker-based taxonomic identification key for the Colombian species is provided. High-resolution images and illustrations, and a distribution map for the species present in the Colombian TDF are provided.

This study aims to examine the psychometric properties of the Spanish adaptation of the Oxford Utilitarianism Scale (OUS-Spa) across three samples. The total sample consisted of 3,427 participants (M = 33.11 years; SD = 13.68; 67% female), including respondents from Spain (n = 1,047), Chile (n = 1,039), and Colombia (n = 1,341). The results support the bifactor structure of the model, which includes the dimensions of Instrumental Harm and Impartial Beneficence, across all three samples. Measurement invariance was confirmed, and the scale demonstrated adequate internal consistency. Additionally, convergent validity was consistent with the psychological profiles associated with the subscales. These findings contribute to the literature on moral decision-making during times of heightened uncertainty, such as the early stages of the COVID-19 pandemic. Impartial Beneficence was positively associated with concerns about the coronavirus and perceptions of personal and global threat. Women scored higher on Impartial Beneficence, while men scored higher on Instrumental Harm. These patterns were consistently observed across all three samples. Older adults in Spain and Chile exhibited higher levels of Impartial Beneficence and lower levels of Instrumental Harm. Overall, the results support the validity of the Spanish version of the OUS, demonstrating a strong alignment with the original inventory.

We report a case of acute/subacute form of paracoccidioidomycosis in a Venezuelan migrant confirmed by the detection of the typical "pilot wheel / mariner's wheel" or "Mickey Mouse" appearance of the budding yeast form of Paracoccidioides in biopsies of a cervical lymph node and a skin lesion.

The pollution of the oceans by plastic waste is one of the major environmental problems of our time. It is estimated that there are millions of tons of polymers floating on the surface of the oceans, concentrated in several large plastic accumulations so-called plastic islands. The main consequence of marine plastic pollution is the negative impact on marine ecosystems and wildlife. The microplastics can be ingested by marine organisms and transferred through the food chain, potentially having harmful effects on human health. Humanity needs to take immediate action to reduce the high number of plastics that end up in the oceans, otherwise the harmful consequences for our oceans and for humanity will be irreversible. In view of this scenario, the present bibliometric review reflects a growing global commitment to sustainability. Major areas of research, including data-driven models for plastic waste management, technological innovations in the circular economy and the impact of microplastics on ecosystems and human health, exemplify the diverse strategies being employed to promote sustainability. Integrating advanced technologies with sustainable practices is crucial to reduce the environmental footprint of plastic waste and mitigate its adverse effects on both marine ecosystems and human health.

Coral diseases have contributed to the decline of coral populations in the Colombian Caribbean. One of the main causes is the infection of pathogenic bacteria, which are transported through marine currents and deposited in the sediment, making it a potential vector and reservoir. In the Torín sector of Isla Aguja, there is an important reef formation of Acropora palmata influenced by river discharges with possible impacts on their condition. To evaluate whether signs of the disease were reducing the population, in 2019, the formation was delimited, and monthly surveys were performed in 65 tagged colonies to calculate the incidence and prevalence of white pox in the population. Samples of water, sediment, healthy mucus and disease mucus were collected to isolate bacterial members and characterize them through amplifications of the V1–V3 hypervariable region of the 16S gene. Because of pandemic restrictions, monitoring was restarted in September 2020 and ended in December 2021, recording only the appearance of signs of disease. Nineteen bacterial strains were isolated. Enterobacter cloacae was found in water and disease mucus, Klebsiella variicola was found in healthy mucus and disease mucus, Klebsiella pneumoniae was found in water and healthy mucus, and Staphylococcus aureus was common in sediment and healthy mucus. Escherichia coli was found only in water. Signs of disease were frequent, with low prevalence but a rapid and evident natural recovery of the colonies, thus not constituting, yet, a threat to the reef formation of A. palmata . In contrast, the gillnets registered on four occasions between 2019 and 2021 caused the breakage of large colonies that impacted the population. It is urgent to establish management strategies for this local formation or strengthen surveillance activities that ensure good fishing practices to protect and prevent impacts on these species.

Excessive daytime sleepiness is highly prevalent and variable in health students. However, a meta‑analysis that synthesises the prevalence of this symptom in dental students has yet to be reported. This review aimed to compute the pooled prevalence of sleepiness in dental students. A systematic review and meta‑analysis of studies published between 2000 and 2023 was developed in Spanish, English, and Portuguese. The keywords were sleepiness, excessive drowsiness, Epworthscale for sleepiness, and dental students in all three languages. Original articles and degree theses that reported the frequency of sleepiness with a cut‑off point for the Epworth scale for sleepiness greater than 10 were included. The sample sizes and the number of students positive for sleepiness were observed, and the prevalence, raw and adjusted for sample size, was calculated. Seven articles were included with participant samples between 128 and 325 students, totalling 1,546. Students were positive on the Epworth scale for sleepiness between 43 and 189, with a sum of 671. The prevalences were between 22.7% and 58.4%; the pooled prevalence was 42.7% (95% CI: 40.3–45.2).In conclusion, sleepiness was present in 4 out of 10 dental students. It is necessary to systematise the factors associated with sleepiness and establish a relationship with the academic performance of dental students.

This study examines community resilience in post-conflict tourism destinations of the Global South, where externally initiated and controlled tourism development often prevails. Using a conceptual research approach grounded in a comprehensive literature review, the paper identifies critical conditions for resilience-building in these fragile contexts. It demonstrates that post-conflict tourism development typically unfolds in three stages: an initial phase of rapid growth driven by external stakeholders, followed by community awakening to tourism’s impacts, and culminating in community-led efforts to regain control. The study argues that even when initial tourism development exceeds local adaptive capacities, it can initiate a gradual process of resilience-building through proactive community action and supportive policies. The transformative potential of amenity migrants is emphasized, as they can shift from being stressors to becoming agents of change, fostering resilience, provided they are successfully integrated into local communities. The paper also advocates for longitudinal research to better understand the dynamics of amenity migrants’ assimilation and their role in resilience-building, particularly in the Global South, where empirical evidence remains limited. The findings provide valuable insights for designing strategies to achieve sustainable and inclusive tourism development in post-conflict and other vulnerable destinations, offering a pathway to empower local communities and foster long-term resilience.

In order to obtain new materials with multifunctional properties, CaLaSnFeO6 samples were synthesized by the solid reaction technique. Structural analysis was performed by X-ray diffraction technique. Rietveld refinement of the experimental data revealed that these materials crystallize in a perovskite-type monoclinic structure (P21/n, space group #14) with alternating arrangement of Fe-Sn cations along the three crystallographic axes. The strongly granular character of the surface of the material was observed by scanning electron microscopy micrographs. X-ray energy dispersive spectra exhibited a close correspondence of the composition of the samples with that expected from their stoichiometric formula. Magnetic characterization in the temperature regime 50 K < T < 325 K and applied fields up to 30 kOe suggests the occurrence of a ferromagnetic ordering with Curie temperature TC = 204 K. Diffuse reflectance spectra revealed the semiconducting characteristic of the CaLaSnFeO6 double perovskite with a bandgap of Eg = 2.33 eV. To establish the origin of the magnetic interactions, electronic structure calculations were performed in the vicinity of the Fermi level by means of the Density Functional Theory. These properties generate technological expectations in the spintronics industry for the production of information storage devices on magnetic media based on polarized spin currents such as spin valves and magnetic transistors.

This study addresses the critical issue of mathematical underperformance among preschoolers in Yopal Casanare, Colombia, through the perspective of an action research project. It focuses on the design and implementation of a didactic unit aimed at promoting numerical thinking, specifically seriation and structured counting, in preschool students. The methodology centers on qualitative action research, combining problem-solving approaches to comprehensively examine and transform educational practices. The intervention was designed to address identified weaknesses in mathematical competencies. To assess the initial state of mathematical competence, the Utrecht Early Mathematical Education Test was administered to 25 transition-grade children, revealing significant deficiencies in seriation and structured counting. The didactic unit included three activities focused on pattern identification, structured counting, and comparison of collections. Post-intervention assessments demonstrated notable improvements in these areas, though the emphasis remains on qualitative insights rather than statistical significance. This study contributes valuable insights into early childhood mathematics education, highlighting the potential of problem-solving-based interventions to enhance foundational mathematical competencies and emphasizing the importance of early diagnostic assessment and targeted educational strategies.

We report a search for neutrino oscillations to sterile neutrinos under a model with three active and one sterile neutrinos ( 3 + 1 model). This analysis uses the NOvA detectors exposed to the NuMI beam, running in neutrino mode. The data exposure, 13.6 × 10 20 protons on target, doubles that previously analyzed by NOvA, and the analysis is the first to use ν μ charged-current interactions in conjunction with neutral-current interactions. Neutrino samples in the near and far detectors are fitted simultaneously, enabling the search to be carried out over a Δ m 41 2 range extending 2 (3) orders of magnitude above (below) 1 eV 2 . NOvA finds no evidence for active-to-sterile neutrino oscillations under the 3 + 1 model at 90% confidence level. New limits are reported in multiple regions of parameter space, excluding some regions currently allowed by IceCube at 90% confidence level. We additionally set the most stringent limits for anomalous ν τ appearance for Δ m 41 2 ≤ 3 eV 2 . Published by the American Physical Society 2025