Resumen Objetivo: Caracterizar la producción por unidad de área de los pastos Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs y Urochloa decumbens (Stapf) R.D. Webster en un sistema de pastoreo racional Voisin con ganado caprino en Manabí, Ecuador. Materiales y Métodos: El área total de estudio fue de 0,22 ha, dividida en once cuartones de cada pasto, con carga animal de 12 caprinos adultos, agua ad libitum y suplementación con bloques nutricionales. Los tratamientos fueron: T1) M. maximus y T2) U. decumbens. Los datos se analizaron con modelos lineales generales y mixtos. Se aplicó un diseño de bloques completos al azar, con nivel de significación de 0.05 (Tukey) y se utilizó el programa R. Durante la época seca del 2022, Se midió la producción del forraje verde/ha, los días de recuperación y el remanente. Resultados: En la producción de forraje verde/ha hubo diferencias (p= 0,0068) y el pasto M. maximus obtuvo los mejores rendimientos (11 800 kg). Este mismo pasto mostró el menor tiempo de descanso (56 días). Se registraron diferencias (p= 0,0036) para el remanente. El promedio más alto se alcanzó en el pasto M. maximus (3 700 kg). Conclusiones: M. maximus y U. decumbens mostraron alta producción de forraje verde por unidad de área en el sistema de pastoreo racional Voisin con ganado caprino, aunque el pasto M. maximus obtuvo mayores rendimientos, mejor recuperación y mayor remanente durante la evaluación.

Abstract Objective: To characterize the production per area unit of Megathyrsus maximus (Jacq.) B.K. Simon & S.W.L. Jacobs and Urochloa decumbens (Stapf) R.D. Webster in a rational Voisin grazing system with goats in Manabí, Ecuador. Materials and Methods: The total study area was 0,22 ha, divided into eleven quarters of each pasture, with a stocking rate of 12 adult goats, water ad libitum and supplementation with nutritional blocks. The treatments were: T1) M. maximus and T2) U. decumbens. Data were analyzed with general linear and mixed models. A randomized complete block design was applied, with a significance level of 0,05 (Tukey) and the R program was used. During the dry season of 2022, green forage production/ha, days of recovery and remnant were measured. Results: In green forage production/ha there were differences (p= 0,0068) and M. maximus pasture obtained the best yields (11 800 kg). This same grass showed the shortest resting time (56 days). Differences (p= 0,0036) were recorded for remnant. The highest average was reached in M. maximus (3 700 kg). Conclusions: M. maximus and U. decumbens showed high green forage production per area unit in the rational Voisin grazing system with goats, although M. maximus obtained higher yields, better recovery and higher remnant during the evaluation.

RESUMEN Este estudio cuestiona las limitaciones ontológicas, metodológicas y epistemológicas de los paradigmas clásicos, neoclásico y marxista para repensar el problema de la transformación y la formación del valor en el circuito económico. Esta aproximación rescata el postulado filosófico de Arthur (2004), primero, para materializarlo en una ecuación teórica que represente la formación del valor en el intercambio, donde la mercancía se transforma en dinero; segundo, para tipificar las formas de reproducción del capital. JEL: B41, B24, B22, B16.

ABSTRACT This study challenges the ontological, epistemological, and methodological limitations of classical, neoclassical, and Marxist paradigms to rethink the problem of transformation and formation of value in the economic circuit. This approach rescues the philosophical postulate of Arthur (2004) firstly, to materialise it, in a theoretical equation that represents the formation of value during the exchange process, where merchandise is transformed into money; secondly, it seeks to typify ways to reproduce capital. JEL: B41, B24, B22, B16.

Abstract This text focuses on different artistic/curatorial practices that, since the late 1980s, have proposed possible responses to the stagnation of institutions and their incapacity to dialogue -from the art system- with conjunctural socio-political processes in the territories of Abya Yala. We make an approach to these situated practices based on G. Pollock's notions of virtuality, D. Haraway's encounter and fabulation, and S. Rivera Cusicanqui's ch'ixi. In them we highlight different poetic/political operations that function as antecedents to propose an artistic/curatorial practice in the present, which we have called Hacer(nos) fuego. The aim of the project is to tension, among others, the following questions: What kind of artistic/curatorial operations can we expect today, in the context of social and pandemic outbursts? In what space-time and with what methodologies could artistic events take place and give rise to other epistemologies?

Resumen Este texto se detiene en distintas prácticas artísticas/curatoriales que, desde finales de los años ochenta, han propuesto posibles respuestas al anquilosamiento de las instituciones y su imposibilidad de dialogar -desde el sistema del arte- con procesos sociopolíticos coyunturales en territorios de Abya Yala. A partir de las nociones de virtualidad de G. Pollock, encuentro y fabulación de D. Haraway, y lo ch’ixi de S. Rivera Cusicanqui, nos aproximamos a estas prácticas situadas. En ellas destacamos distintas operaciones poéticas/políticas que funcionan como antecedentes para proponer una práctica artística/curatorial en el presente, que hemos llamado Hacer(nos) fuego. Esta busca tensionar, entre otras, las siguientes preguntas: ¿Qué tipo de operaciones artístico/curatoriales podemos pensar hoy, en el contexto de los estallidos sociales y pandémicos? ¿En qué espacio-tiempo y con qué metodologías pueden ocurrir acontecimientos artísticos que den lugar a otras epistemologías?

Abstract Chilecomadia valdiviana (Lepidoptera, Cossidae), locally known as "Gusano del Tebo", is a polyphagous pest that, in its larval stage, feeds on the wood of the host species. C. valdiviana is distributed in the southern region of Chile and Argentina and its larvae mainly attack eucalyptus and fruit trees. Previous research has reported the identification of the volatile compounds produced by this species in its larval stage. In this work, the effects of two dietary conditions on these volatile compounds were described: groups of individuals fed with wood vs. others without food. The results obtained provide empirical evidence that C. valdiviana modulates the emission of the compounds according to the effect of stimulus.

Abstract This article describes the virtues of a research focused on silicon, one of the most important but least known ingredients in beer, and its protective action at the neurodegenerative level. Among the various factors contributing to the Alzheimer's disease induction and development, aluminum, by concentrating in brain induces, among other mechanisms, pro-oxidant and inflammatory disorders. Silicon, by blocking these negative effects, becomes a star ingredient, which in alchemist terms suggests that has the property to transmute into gold.

Resumen Este trabajo describe las virtudes de una investigación centrada en el silicio, uno de los ingredientes más importantes pero menos conocidos de la cerveza, y su acción protectora a nivel neurodegenerativo. Entre los varios factores que contribuyen a la inducción y desarrollo de la enfermedad de Alzheimer, se encuentra el aluminio el cual tiende a concentrarse en el cerebro e inducir, entre otros mecanismos, alteraciones prooxidantes e inflamatorias. El silicio al bloquear esos efectos negativos, se convierte en un ingrediente estrella, que en términos alquimistas sugiere que puede transmutar en oro.

Abstract: Feeding habits of the ichthyoplankton from Chilean Patagonia (44-46°30’S) were studied during June-July 2012 (austral winter). Ichthyoplankton assemblage was composed by 10 species, with low abundance (3.8 to 16.73 ind. 1000 m-3). Most abundant larvae were Maurolicus parvipinnis, Leptonotus blainvilleanus and Sprattus fuegensis. These three species fed mainly on calanoid copepodites, Paracalanus indicus and Calanus sp. copepodites, and cyphonautes. Trophic overlap among dominant fish larvae was high (Schoener’s D > 0.69) and no significant differences were detected in prey composition and size. Therefore, no resource partitioning occurred in planktonic fish larvae during winter 2012 in Chilean Patagonia.

Resumen El presente trabajo tiene como objetivo ahondar en los conceptos de “motivación escolar” y “compromiso escolar” en el contexto de los procesos educativos, examina en qué medida las conceptualizaciones que ofrece la bibliografía anglosajona son compatibles o están representadas en la iberoamericana, con miras a precisar con mayor detalle sus diferencias para favorecer futuras investigaciones o intervenciones. Para ello, se llevó a cabo una revisión teórica que pone en discusión los avances en el análisis de ambos conceptos, se descubrieron similitudes y diferencias en las dimensiones constitutivas de cada una. La de origen iberoamericano trata ambos conceptos como homologables entre sí y produce confusiones conceptuales. Esta revisión permite precisar las diferencias, lo que puede ser de utilidad para favorecer futuras investigaciones o intervenciones.

Abstract The present research work aims at gaining understanding of what it is referred as “motivation” and “engagement” in the context of educational processes considering points of consensus and debate in the specialized literature. The objective was examining how far the definitions that have been proposed by authors from English-speaking contexts are compatible or have been represented in writings from Iberoamerican context attempting to clarify how are these two constructs related to each other. A review was performed focusing on manuscripts that discussed advances in these subjects. The main conclusions from this revision highlight the similarity of some definitions for both concepts. It is shown that both concepts are being treated as equivalent to each other, enabling potential conceptual confusions. The need for further debating about the relationship between both kinds of processes aiming at achieving higher clarity regarding the differences between the concepts to help future research and interventions is proposed.

Background: Hypovitaminosis D has a high prevalence among patients with chronic kidney disease (CKD). Aim: To determine the prevalence of 25 hydroxy vitamin D (25(OH) D) insufficiency and deficiency in pediatric patients on dialysis and kidney transplantation. Material and Methods: Serum calcium and phosphorus, parathormone (PTH), alkaline phosphatases and 25 (OH)D were measured in 13 children on hemodialysis (HD), 18 on peritoneal dialysis (PD) and 53 that received an allograft (Tx), aged 9.8 ± 4.6 years (51% females). Results: Fifty four percent of patients had height Z score less than -1.88. Patients on HD had the lowest values. The average time of replacement therapy was 2.9 ± 2.8 years. Mean 25(OH)D levels in all was 18.7 ± 10.7ng/ml (HD: 21 ± 16.8, PD: 18.9 ± 8.5, Tx: 18.1 ± 9.72 ng/ml). Eighty eight percent of patients had levels below 30 ng/ml. Mean of serum calcium was 9.5 ± 0.64 mg/dl, serum phosphorus 5.03 ± 1.02 mg/dl, calcium-phosphorus product 48 ± 11.8 mg/dl and alkaline phosphatases 300.5 ± 171.3 IU/L. Average PTH values in dialyzed and Tx patients were 724.6 ± 640.5 and 107.7 ± 56.2 pg/ml, respectively (p < 0.001). A positive correlation between 25 (OH) D and calcium levels among PD patients was observed (r = 0.490, p = 0.04). Conclusions: Hypovitaminosis D is highly prevalent among children on renal substitution therapy, regardless of the type of therapy used and the stage of renal failure.

The hRAD54 gene is a key member of the RAD52 epistasis group involved in repair of double-strand breaks (DSB) by homologous recombination (HR). Thus, alterations of the normal function of these genes could generate genetic instability, shifting the normal process of the cell cycle, leading the cells to develop into cancer. In this work we analyzed exon 18 of the hRAD54 gene, which has been previously reported by our group to carry a silent polymorphism, 2290 C/T (Ala730Ala), associated to meningiomas. We performed a PCR-SSCP method to detect the polymorphism in 239 samples including leukemia and normal control population. The results revealed that the 2290 C/T polymorphism has frequencies of 0.1 for the leukemia and 0.1 for the control group. These frequencies show no statistical differences. Additionally, we dissected the leukemia group in chronic myelogenous leukemia (CML) and acute lymphoblastic leukemia (ALL) to evaluate the polymorphism. The frequencies found in these subgroups were 0.14 for CML and 0.05 for ALL. We found statistically significant differences between CML patients and the control group (p < 0.05) but we did not find significant differences between ALL and the control group (p > 0.05). These results suggest a possible link between the 2290 C/T polymorphism of the hRAD54 gene and CML.

We analyzed the consequences of aerial spraying with glyphosate added to a surfactant solution in the northern part of Ecuador. A total of 24 exposed and 21 unexposed control individuals were investigated using the comet assay. The results showed a higher degree of DNA damage in the exposed group (comet length = 35.5 µm) compared to the control group (comet length = 25.94 µm). These results suggest that in the formulation used during aerial spraying glyphosate had a genotoxic effect on the exposed individuals.