Utilización del modelo de Lagrange para la enseñanza de extremos condicionados

Existe gran cantidad de publicaciones que tratan del rol que cumple la Matemática en la Economía. Este tema, nos lleva a reflexionar sobre el papel que debe cumplir la Economía en las clases de Matemática y de qué manera debe enseñarse Matemática a estudiantes de Economía para facilitar la construcción del pensamiento lógico necesario para organizar, seleccionar, sistematizar la información que se nos suministra y para relacionar, integrar, inferir conceptos, ideas y principios matemáticos. En este trabajo se utiliza el Modelo de Lagrange con el objeto de motivar el aprendizaje de Extremos Condicionados para estudiantes de Economía, aunque tiene plena validez para ser aplicado en otras disciplinas

Utilización de un modelo de crecimiento económico para la enseñanza de ecuaciones diferenciales

Uno de los objetivos de la investigación en el contexto de la Matemática educativa es promover metodologías que fortalezcan sus procesos de enseñanza-aprendizaje. Si se pretende que los alumnos manejen criterios que le permitan optimizar un proyecto desde su concepción para obtener los mejores resultados, debe transformarse la clase en una instancia fuertemente interactiva, de modo que los conocimientos aprendidos queden grabados en la mente de esos futuros profesionales. Este trabajo muestra el uso de un Modelo de Crecimiento Económico como motivación para la enseñanza de Ecuaciones Diferenciales en carreras de Economía. Al respecto, introduciendo problemas vinculados con la especialidad se posibilita la interacción entre la matemática y otras ciencias, como por ejemplo la economía

Propagation of Artemisia arborescens L. by stem-cutting: adventitious root formation under different conditions

Artemisia arborescens L. has gained a strong importance worldwide due to its many industrial uses and it has been recently considered as ornamental plant. A major constraint to its widespread cultivation is represented, by far, by the scarce availability of high-quality plant material for field establishment; hence, development of a fast and effective methods for its vegetative propagation is needed. An experiment was conducted to assess the effects of different harvest periods, NAA, and rooting substrates on rooting of stem cuttings of A. arborescens. Semi hardwood cuttings were collected from wild plants in February, April, and November. Half of the material was treated with 0.4% NAA and placed on different mixtures of sphagnum peat and perlite (2 : 1, 1 : 1, and 1 : 2 v/v) under mist. After 40 days the percentage of rooted cuttings was significantly influenced by the harvest period as cuttings collected in February showed the highest rooting rate, and numerous alive but not rooted cuttings evidenced callus formation. In contrast, the use of different rooting substrates as well as NAA addition did not show any significant effect on rooting capacity. The best results, in terms of root number (4.2) and root length (8.8 cm), were achieved on cuttings grown in a 1 : 1 v/v sphagnum peat : perlite mixture, without NAA application

AUTOMATIZACIÓN DE LA INFORMACIÓN CLÍNICA ODONTOLÓGICA: UN PROYECTO DE SOFTWARE ÍNTEGRAMENTE ESPAÑOL

Sin resume

Use of biochar as peat substitute for growing substrates of Euphorbia × lomi potted plants

Biochar from conifers wood was used in soilless culture as growing substrate alternative to peat for ornamental crops. Potted plants of Euphorbia × lomi Rauh cv. 'Ilaria' were grown with different mixtures (v:v) of brown peat and biochar in order to evaluate main physical and chemical characteristics of this biomaterial as well as its effect on plant growth, ornamental characteristics and nutrients uptake. Biochar addition to peat increased pH, EC and K content of the growing substrates, as well as air content and bulk density. Biochar content of substrates significantly affected plant growth and biomass partitioning: higher number of shoots and leaves, leaf area and leaf dry weight were recorded in plants grown in 40% peat-60% biochar, with respect to plants grown in 100% peat and secondarily in 100% biochar. Leaf chlorophyll content was higher in plants grown in 60% and 80% biochar, while biomass water use efficiency was higher with 60% biochar. Plant uptake of K and Ca increased as biochar content of the substrates increased. Hence, a growing substrate containing 40% brown peat and 60% conifers wood biochar was identified as the more suitable mixture allowing to have a high-quality production of Euphorbia × lomi potted plants

Biochar enhances root development and aloin content of mature leaves in containerized Aloe arborescens Mill

The leaves of the medicinal plant Aloe arborescens Mill. Asphodelaceae) contain significant amounts of bioactive metabolites, including aloin (a mixture of the two diastereoisomers, aloin A and aloin B), aloesin, isoaloeresin D, and aloenin A. The presence of these metabolites varies considerably depending on the plant’s growth conditions, including the used growing substrate. In recent years, there has been growing interest in using biochar for potted plants cultivation. However, there is currently no available information regarding the suitability of biochar for the containerized cultivation of A. arborescens. A pot experiment was conducted with the hypothesis that biochar could influence the growth and phytochemistry of A. arborescens. The growing medium was supplied with increasing proportions of biochar (1: 100% commercial substrate; 2: mixed 50%(v/v) substrate; 3: 100% conifers wood biochar). Over the course of three years, the plants were closely monitored, and several key growth parameters were measured, including plant height, stem diameter, number and weight of leaves, and the number of suckers. After the first year, the content of selected active metabolites wasassessed. This evaluation also involved a comparison of the respective levels in the leaves taken from the apical, median, and basal sections of the stem. The leaves collected from the median section of plants were found to be larger and exhibited the highest percentage of spikes, epidermis, and gel on fresh weight. As a general trend, it was observed that in plants cultivated within the highest amount of biochar, the leaves collected from the intermediate stem portion contained the highest quantity of secondary metabolites

EFFETTI DEL CAMPO MAGNETICO ELF SU ALCUNE SPECIE VEGETALI DI INTERESSE ORNAMENTALE ED ECOLOGICO

Diversi studi riportati nella letteratura scientifica di riferimento, effettuati sia in vivo che in vitro, hanno evidenziato effetti positivi determinati dall’esposizione dei tessuti vegetali al campo magnetico EL

Una propuesta para la enseñanza de los fractales en el nivel medio

El siguiente trabajo es una propuesta de enseñanza para alumnos de 2º año del nivel Secundario que tiene como propósito hacer conocer el por qué, el para qué y el cómo introducir conceptos de la geometría fractal en dicho nivel. El estudio de los fractales permite relacionar lo científico, con la tecnología, el arte, etc. Es una excelente ocasión para introducir a los alumnos en el nuevo mundo a que dieron lugar estos maravillosos objetos matemáticos que encuentran tantas representaciones en el mundo que nos rodea ya que resulta de interés por muchas razones, y no sólo por las de tipo curricular que se mencionó al principio, sino además por la actualización científica y el enorme potencial interdisciplinar de estos objetos. Entre sus objetivos se pretende mostrar dos aspectos básicos que pueden tenerse en cuenta para mejorar y fomentar la enseñanza de la Matemática y en particular de la Geometría: el dinamismo y la evolución de la ciencia, a partir de la presentación y construcción de fractales; y las aplicaciones variadas de los fractales que tienen en los distintos campos del conocimiento

Chemical composition and biological activities of essential oils from Origanum vulgare genotypes belonging to the carvacrol and thymol chemotypes

The remarkable biological activities of oregano essential oils (EOs) have recently prompted a host of studies aimed at exploring their potential innovative applications in the food and pharmaceutical industries. The chemical composition and biological activities of EOs from two Origanum vulgare genotypes, widely cultivated in Sicily and not previously studied for their biological properties, were characterized. Plants of the two genotypes, belonging to the carvacrol (CAR) and thymol (THY) chemotypes and grown in different cultivation environments, were considered for this study. The chemical profiles, including the determination of enantiomeric distribution, of the EOs, obtained by hydrodistillation from dried leaves and flowers, were investigated by GC-MS. Biological activity was evaluated as antimicrobial properties against different pathogen indicator strains, while intestinal barrier integrity, reduction in pathogen adhesion and anti-inflammatory actions were assayed in the intestinal Caco-2 cell line. The chemical profile of the CAR genotype was less complex and characterized by higher levels of the most active compound, i.e., carvacrol, when compared to the THY genotype. The enantiomeric distribution of chiral constituents did not vary across genotypes, while being markedly different from that observed in Origanum vulgare genotypes from other geographical origins. In general, all EOs showed high antimicrobial activity, both in vitro and in a food matrix challenge test. Representative EOs from the two genotypes resulted not altering epithelial monolayer sealing only for concentrations lower than 0.02%, were able to reduce the adhesion of selected pathogens, but did not exert relevant anti-inflammatory effects. These results suggest their potential use as control agents against a wide spectrum of foodborne pathogens