National University of Luján

Mathematical modeling of virus dynamics is key to depicting the evolutionary pathways that lead to virus emergence, transmission, and persistence. Typically, viruses are populations of closely related genomes that continuously change their configuration and adapt to environmental selection pressures. In this work, we revisit this idea by considering viruses as active particles that dynamically shape their ecological niche. To this end, we adapt the Kinetic Theory of Active Particles to model virus interactions, allowing payoffs to co-evolve as a function of the populations configuration. We deduce the system of ordinary equations corresponding to the replicator dynamics with frequency-dependent payoffs. Then we obtain a nonlinear integro-differential equation describing the dynamics for a continuum of strategies by passing to the limit in the replicator system when the number of equations grows. Finally, we present some examples of virus dynamics.

Orf virus (ORFV) is the etiological agent of Contagious Ecthyma, a global disease that mainly affects sheep, goats, wild ruminants, and humans. Here, we determined the complete genome sequence of two ORFV strains from Spain (NAV and ARA) and two from Argentina (HRE and CHB), representing the first report from the Iberian Peninsula and from South America. The assembled genomes of the ARA, CHB, HRE, and NAV strains of ORFV were found to be 137 891, 137 160, 137 340, and 137 214bp long, respectively, each contained 132 genes, and all showed high amino-acid identity and similar lengths compared to the reference strain NZ2. We performed a microsatellite analysis to identify molecular signatures associated with host species (sheep or goat). In addition, the analysis of 32 selected genes showed that the median nucleotide substitution rate for the worldwide cluster 3 that includes the four samples described in this study, was 2.6 x10-5 subs/site/year (9.2x10-8-6.7x10-5-95% HPD) placing the TMRCA (median divergence time) around 1730. Genetic characterization of ORFV strains not only allows epidemiological studies but also represents the first step towards developing molecular tools for diagnostics and vaccines.

Abstract Plant phenolics play a key role in plant defence mechanisms against both biotic and abiotic stressors. However, their responses to environmental variables and grazing pressure across large geographical scales remain poorly understood. Using data from a global survey of 325 plots spanning six continents, we examined how climatic factors, soil properties, leaf nutrients and grazing pressure shape leaf phenolic concentration in 1854 plant species (1280 herbaceous and 574 woody) across global drylands. Our findings reveal that leaf phenolic concentration in herbaceous plants was mainly influenced by grazing pressure and its interactions with leaf nitrogen and iron, which together explained over 50% of observed variation across global drylands. Conversely, phenolic concentration in woody plants was strongly associated with climatic factors, particularly mean annual precipitation (MAP) and mean annual temperature (MAT), which accounted for 80% of the observed variation. While MAP had a positive effect on leaf phenolic concentration in woody plants, grazing pressure buffered this relationship by reducing the influence of MAP. Synthesis. Our study advances the understanding of how biotic and abiotic stressors shape plant defence strategies in global drylands. Our findings shed novel insights about how plant secondary metabolites and their associated functions shift in response to changes in climate and grazing pressure, two key global change drivers with significant implications for ecosystem resilience in drylands worldwide.

En la enseñanza de los deportes de equipo, la pedagogía no lineal concibe al sujeto practicante como un sistema dinámico y complejo en constante interacción con su entorno. Esta interacción genera patrones de comportamiento que evolucionan en función de las condiciones del sistema. Cuando se introduce una variable externa, el equilibrio del sistema se altera, dando lugar a un nuevo estado. Esta variable externa, conocida como constreñimiento o restricción, puede ser manipulada estratégicamente para promover la aparición de determinados comportamientos tácticos. Desde esta perspectiva, el diseño de ejercicios debe basarse en cuatro principios pedagógicos fundamentales a saber: la complejidad táctica, la representatividad de la tarea, la exageración y el muestreo. Este escrito revisa estudios que analizan el comportamiento táctico desde la pedagogía no lineal y discute los procedimientos para diseñar ejercicios en el contexto del rugby. A partir de la evidencia revisada, se concluye de manera preliminar que la pedagogía no lineal representa una herramienta útil para el desarrollo de ejercicios que optimicen los comportamientos tácticos en el rugby.

En los últimos años la formación de profesores de Biología ha empezado a reconfigurarse al ritmo de debates que exceden el aula. La sanción de la Ley 27.621 y la reforma de los profesorados bonaerenses plantean una pregunta simple y urgente: ¿puede la Educación Ambiental superar la lógica de los contenidos fragmentados para constituirse en un eje crítico que transforme la práctica docente y las relaciones con los territorios? En este ensayo sostengo que el nuevo diseño curricular ofrece un horizonte crítico, pero que su puesta en marcha exige disputar sentidos, metodologías y condiciones institucionales en los institutos formadores.

El objetivo de este trabajo es realizar una caracterización hidrometeorológica y climática de la cuenca del río Luján, empleando los registros hidrométricos y meteorológicos disponibles en la zona, con el fin de analizar la variabilidad temporal y espacial de dos variables fundamentales: la precipitación y el caudal. Se empleó el método de Thiessen para definir las áreas de influencia de cada estación meteorológica, análisis de tendencias interanuales con el coeficiente de correlación de Pearson y ajuste polinómico de tercer grado, así como estudios de distribuciones de probabilidad y determinación de períodos de retorno mediante el software Hydrognomon 4.1. Los resultados indican una tendencia decreciente en las precipitaciones anuales en todas las estaciones, con valores medios de 995,50 mm en Suipacha, 988,67 mm en Mercedes y 1.064,01 mm en Luján. Se identificó un ciclo estacional de precipitaciones con máximos en verano y primavera y mínimos en invierno. En cuanto a la distribución de probabilidad de las precipitaciones máximas diarias anuales, la mejor representación se logró con la distribución Gumbel en Suipacha y Luján, mientras que en Mercedes se ajustó mejor a la Log Pearson III. El análisis de caudales se realizó mediante aforos en puntos estratégicos del cauce principal utilizando Perfilador Acústico de Efecto Doppler (ADCP, por sus siglas en inglés: Acoustic Doppler Current Profiler), cuyos datos fueron procesados con el software QRev. Se determinaron curvas altura-caudal mediante modelos de regresión exponencial, que mostraron ajustes con coeficientes de determinación superiores a 0,97. Se observó una disminución en los caudales máximos y mínimos, con valores del índice de fluctuación cercanos a cero. Las curvas de duración de caudales evidenciaron una pendiente pronunciada en los tramos iniciales, indicando la ocurrencia de caudales elevados en períodos breves. En la estación de Ruta 6, el caudal del 2% alcanzó 92,41 m³/s, mientras que en Jáuregui fue de 79,25 m³/s. En cuanto al Q95%, representativo de sequía, presentó valores similares en todas las estaciones de aforo, con 2,14 m³/s en Ruta 6 y 2,08 m³/s en Jáuregui. Estos hallazgos resaltan la importancia del monitoreo hidrometeorológico continuo para mejorar la gestión de los recursos hídricos en la cuenca del río Luján.

Empowerment can be thought of as a gain of power and autonomy by an unfavored group, which creates a better situation. Women in Science (WIS) face multiple barriers that ultimately affect their performance. There is an urgent need to reverse the inequalities and disadvantages that WIS face. With this aim, in May 2023, 17 WIS gathered in person for four days in a workshop entitled Empowering Women in Science. As an outcome of the workshop, we cooperatively started to draw up a list of empowerment recommendations. We continued working together for more than a year to improve this list, which we now present as the Good Practice Guide for Empowering Women in Science (GPG). The GPG contains recommendations across the individual, collective and system levels that we believe help address inequalities for WIS. The aim of this debate is twofold: a) to present the GPG and b) to use the GPG to self-evaluate the number of actions we, the authors, undertook before and after participating in the workshop. Results show that one year after ending the workshop, we doubled the number of actions performed across all categories assessed: I) identify, confront and make visible systemic barriers; II) self-promotion; III) promote other women, and IV) foster diversity, equity and inclusion. This suggests that empowerment can be fostered through formal training programs and discussion spaces. We hope that the GPG will inspire WIS across disciplines and backgrounds to: A) act towards empowerment (at the individual, collective and system level); B) embrace the notion that each of us can be part of the change that we want to see happening towards higher equity for WIS, and C) recognize that any action is better than inaction. Finally, the GPG provides a framework that will continue to be improved and expanded with the feedback of readers and users.

Abstract The composition of the bat assemblage in the middle course of the Uruguay river (Argentina) was studied and compared with other assemblages along this same river. A total of 55 individuals belonging to 11 species from the families Molossidae (4), Phyllostomidae (3) and Vespertilionidae (4) were captured using mist nets at different sites. These species belong to six trophic guilds; the highest specific richness correspond to the insectivorous guild, but the most common bat was the frugivorous Sturnira lilium . Additionally, we reported the southernmost record in Argentina for the frugivorous bat Artibeus lituratus . Finally, we discussed the conservation, importance and distribution of these mammals in riparian environments.

Reseña Martinelli, Martín Alejandro (2025) Geopolítica del Genocidio en Gaza. Buenos Aires: Batalla de Ideas, 243 páginas ISBN 978-631-90520-5-3