104 research outputs found
Evolución de la teoría económica de las finanzas: una breve revisión
Para todos los profesionales interesados en el área de las finanzas, sean o no economistas, es muy importante lograr un detallado conocimiento sobre las técnicas y herramientas que se pueden emplear para valorar el riesgo y el rendimiento de aquellos activos en los que se desea invertir. Este artículo presenta una breve y clara descripción de los distintos modelos que se han desarrollado desde el año 1952, año en el que Harry Markowitz presentó su teoría de portafolios, hasta nuestros días. En otros términos este trabajo presenta la evolución o estado del arte de la Teoría económica de las finanzas.Teoría Económica de las Finanzas, Modelo CAPM, Mode- lo APT, Modelo OPM, Riesgo, Valoración de Activos
EVOLUCIÓN DE LA TEORÍA ECONÓMICA DE LAS FINANZAS: UNA BREVE REVISIÓN
For all tose professionals interested in the field of finances, be theyeconomists or not, it is of the most importance to reach a detailed knowledge over the techniques ans instruments that can be used in order to evaluate the risks and the performances of those assets in which one may wish to invest.This article presents a brief yet clear description over the various models that have been developed since 1952, the year in which Harry Markowitz first introduced his portfolio theory. In other words, this essay presents the evolution or the State-of-the-art of the economical Theory in FinancingPara todos los profesionales interesados en el área de las finanzas, sean o no economistas, es muy importante lograr un detallado conocimiento sobre las técnicas y herramientas que se pueden emplear para valorar el riesgo y el rendimiento de aquellos activos en los que se desea invertir. Este artículo presenta una breve y clara descripción de los distintos modelos que se han desarrollado desde el año 1952, año en el que Harry Markowitz presentó su teoría de portafolios, hasta nuestros días. En otros términos este trabajo presenta la evolución o estado del arte de la Teoría económica de las finanzas.
"Casa / Casae" en el Occidente romano
Examines social and economic envolvements of the latin term casa compared to the other kinds of buildings in the rural habitat as tugurium, capana, villula and villa. The means of transport demanded the existence of casae even as mansio from a public highway oder as caput civitatis. The were both casae ower as tenants, coloni, during the Republic and during all phases of the Empire. The place namen ending in -ana can be precedy by the term villa or by the term casa.Se analizan las Implicaciones sociales y económicas del término latino casa frente a otras formas de habitación en el medio rural como tugurium, caparía, villula y villa. Los medios de transporte exigían la existencia de casae, incluso como mansio de una vía pública o como cabecera de civitas. Hubo tanto propietarios como arrendatarios, coloni, de casae durante la República y durante todas fases del Imperio. Los topónimos terminados en -ana pueden ir precedidos del término villa o del término casa
Economic Valuation of Cultural Heritage: Application of Travel Cost Method to the National Museum and Research Center of Altamira
The economic assessment of non-marketed resources (i.e., cultural heritage) can be developed with stated or revealed preference methods. Travel cost method (TCM) is based on the demand theory and assumes that the demand for a recreational site is inversely related to the travel costs that a certain visitor must face to enjoy it. Its application requires data about the tourist?s origin. This work aims to analyze the economic value of the National Museum and Research Center of Altamira, which was created to research, conserve, and broadcast the Cave of Altamira (UNESCO World Heritage Site since 1985). It includes an accurate replica known as the ?Neocave?. Two different TCM approaches have been applied to obtain the demand curve of the museum, which is a powerful tool that helps to assess past and future investments. It has also provided the annual economic value estimate of the National Museum and Research Center of Altamira, which varies between 4.75 and 8.00 million € per ye
Rapid alteration of cellular redox homeostasis upon exposure to cadmium and mercury in alfalfa seedlings.
Summary • Here, the kinetics of oxidative stress responses of alfalfa ( Medicago sativa ) seedlings to cadmium (Cd) and mercury (Hg) (0, 3, 10 and 30 µ M ) exposure, expanding from a few minutes to 24 h, were studied. • Intracellular oxidative stress was analysed using 2 ′ ,7 ′ -dichlorofluorescin diacetate and extracellular hydrogen peroxide (H 2 O 2 ) production was studied with Amplex Red. Growth inhibition, concentrations of ascorbate, glutathione (GSH), homoglutathione (hGSH), Cd and Hg, ascorbate peroxidase (APX) activity, and expression of genes related to GSH metabolism were also determined. • Both Cd and Hg increased cellular reactive oxygen species (ROS) production and extracellular H 2 O 2 formation, but in different ways. The increase was mild and slow with Cd, but more rapid and transient with Hg. Hg treatments also caused a higher cell death rate, significant oxidation of hGSH, as well as increased APX activity and transient overexpression of glutathione reductase 2, glutamylcysteinyl synthetase, and homoglutathione synthetase genes. However, Cd caused minor alterations. Hg accumulation was one order of magnitude higher than Cd accumulation. • The different kinetics of early physiological responses in vivo to Cd and Hg might be relevant to the characterization of their mechanisms of toxicity. Thus, high accumulation of Hg might explain the metabolism poisoning observed in Hg-treated seedlings
Economic Valuation of Mining Heritage from a Recreational Approach: Application to the Case of El Soplao Cave in Spain (Geosite UR004)
Heritage tourism can increase incomes and stimulate the economy in former mining areas. Recreational tourism is one of the main sources of value of heritage. People from urban areas are willing to pay for access to these tourism options. The measurement of the economic impact of this availability is one of the main problems to confront, due to the immeasurable possibilities of heritage resources. The use of non-market values and their estimation by means of revealed preference methods should help to assess the economic value of this sort of resources from a recreational perspective. The travel cost method (TCM) is widely used to value areas with recreational uses, such as lakes, beaches or forests, but there are not references to previous applications of this methodology in the field of mining heritage. In this work, TCM has been applied to obtain the economic value of El Soplao Cave (Geosite UR004, Cantabria, Spain) as a recreational site, providing an estimated
result of 34,961,162 euros
El Gorrión Serrano (Xenospiza baileyi): síntesis sobre la historia natural, estudios científicos y acciones para la conservación de un ave micro endémica de México en peligro de extinción
La conservación enfocada en especies endémicas es prioritaria dada su alta vulnerabilidad. Para lograrla resulta imprescindible conocer la historia natural de las especies. El Gorrión Serrano (Xenospiza baileyi), catalogado en peligro de extinción, es una de las aves endémicas más vulnerables de México (valor de vulnerabilidad máximo = 20). Su estudio ha sido intermitente y la información asociada a su historia natural se encuentra dispersa, no publicada o es de difícil acceso. En este trabajo se sistematizó, examinó y actualizó el conocimiento relacionado con la historia natural de X. baileyi. Se compilaron estudios sobre esta especie para identificar vacíos en torno a su investigación. Se lograron integrar aspectos de la historia natural de X. baileyi relacionados con su taxonomía, descripción, distribución, hábitat, demografía, dispersión, territorialidad, alimentación, interacciones ecológicas, perchas, vocalizaciones, ciclo reproductivo, cortejo, nido, huevos, pollos y amenazas. Además, se incluyó información nueva resultante de actividades de monitoreo comunitario sobre esta especie, lo cual permitió denotar la importancia de la inclusión comunitaria para el manejo y conservación de la especie y su hábitat. Esta información resulta fundamental para optimizar su estudio y orientar las acciones urgentes en torno a su conservación.The conservation of endemic species deserves priority attention given their high vulnerability. Information about the natural history of species is essential for achieving conservation goals. The Sierra Madre Sparrow (Xenospiza baileyi) is an endangered species that is considered to be one of the most vulnerable endemic birds of Mexico (maximum vulnerability value = 20). Its study has been intermittent and the information about its natural history is disperse, unpublished, or difficult to access. This work systematized, evaluated, and updated the knowledge regarding the natural history, taxonomy, description, distribution, habitat, demography, dispersion, territoriality, feeding behavior, ecological interactions, perches, vocalizations, breeding cycle, courtship displays, nest, eggs, nestlings, and threats to the conservation of X. baileyi. In addition, we included novel information generated through community-based monitoring activities, which also highlighted the relevance of including local communities for managing and conserving the species and its habitat. This information is key for optimizing research and guiding urgent conservation actions on the species
Ecological filtering shapes the impacts of agricultural deforestation on biodiversity
Funding: This project was funded by the National Natural Science Foundation of China (Grants 32122057 and 3198810 to FH) and the Ministry of Science and Technology of China (Grant 2022YFF0802300 to FH), and received further support from Tsinghua University Initiative Scientific Research Program (Grant 20223080017 to LY).The biodiversity impacts of agricultural deforestation vary widely across regions. Previous efforts to explain this variation have focused exclusively on the landscape features and management regimes of agricultural systems, neglecting the potentially critical role of ecological filtering in shaping deforestation tolerance of extant species assemblages at large geographical scales via selection for functional traits. Here we provide a large-scale test of this role using a global database of species abundance ratios between matched agricultural and native forest sites that comprises 71 avian assemblages reported in 44 primary studies, and a companion database of 10 functional traits for all 2,647 species involved. Using meta-analytic, phylogenetic and multivariate methods, we show that beyond agricultural features, filtering by the extent of natural environmental variability and the severity of historical anthropogenic deforestation shapes the varying deforestation impacts across species assemblages. For assemblages under greater environmental variability—proxied by drier and more seasonal climates under a greater disturbance regime—and longer deforestation histories, filtering has attenuated the negative impacts of current deforestation by selecting for functional traits linked to stronger deforestation tolerance. Our study provides a previously largely missing piece of knowledge in understanding and managing the biodiversity consequences of deforestation by agricultural deforestation.Peer reviewe
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