Modelo para el pronóstico financiero de siembra y comercialización de tubérculos: Caso Ñame.

Proyecto de Graduación (Maestría de Administración de Empresas con énfasis en Finanzas) Instituto Tecnológico De Costa Rica. Escuela de Administración de Empresas, 2015.El presente trabajo propone un modelo financiero para la predicción de rentabilidad en el sector agrícola de tubérculos (Ñame), a través del uso de técnicas, herramientas y teorías financieras. Durante el desarrollo del diagnóstico, se determinó que el cultivo de ñame es poco tecnificado y cuenta con un manejo muy “rústico”, es decir, se conoce poco sobre herramientas de diagnóstico financiero que permita demostrar la rentabilidad de este cultivo. Por lo tanto, este modelo expresa de una forma práctica y sencilla, ciertas variables financieras que determinan la rentabilidad de la siembra y comercialización del cultivo del ñame, con las cuales se demuestra que la rentabilidad del cultivo del es muy inestable, debido a las inconstantes productividades y cambios en el precio de venta. Se recomienda aplicar el modelo por separado para las cosechas de mercado nacional, como para las cosechas a exportar, esto porque los precios puede variar de un mercado a otro, al tener dos contextos diferentes las valoraciones deben darse por separados para la obtención de un valor real. Por último se recomienda en la medida de lo posible, realizar un estudio de riesgo que complemente los resultados del modelo financiero, en el modelo realizado en este trabajo no contempla el factor riesgo.Instituto Tecnológico de Costa Rica. Escuela de Administración de Empresas

Tropical Dry Forest Succession and the Contribution of Lianas to Wood Area Index (WAI)

The transmission and interception of light through the canopy is an important indicator of forest productivity in tropical forest ecosystems, and the amount of light that eventually reaches the forest floor is influenced by its interactions with leaves, branches, fruits, and flowers among many different canopy elements. While most studies of forest canopy light interception focus on leaf area index (LAI), very few studies have examined wood area index (WAI), which may account for a substantial component of light interception in tropical forests. The influence of lianas on the interception of light and their overall contribution to WAI is a potentially important factor, but it is generally overlooked because of its difficulty to assess. In this paper we evaluate the relative contribution that lianas have to the overall WAI and canopy openness as function of successional stage via a latitudinal comparison of sites across the Americas (Mexico, Costa Rica and Brazil). Our results suggest that lianas significantly increase WAI and decreases canopy openness. However, lianas were absent at all of our study sites where canopy openness exceeded 60%. Our data are the first to explicitly document the role of lianas in the estimation of WAI and, overall, they will contribute to better estimations of ecosystem level LAI in tropical environments, where there is a lack of data on WAI

A Review of the Enviro-Net Project

Ecosystems monitoring is essential to properly understand their development and the effects of events, both climatological and anthropological in nature. The amount of data used in these assessments is increasing at very high rates. This is due to increasing availability of sensing systems and the development of new techniques to analyze sensor data. The Enviro-Net Project encompasses several of such sensor system deployments across five countries in the Americas. These deployments use a few different ground-based sensor systems, installed at different heights monitoring the conditions in tropical dry forests over long periods of time. This paper presents our experience in deploying and maintaining these systems, retrieving and pre-processing the data, and describes the Web portal developed to help with data management, visualization and analysis.Comment: v2: 29 pages, 5 figures, reflects changes addressing reviewers' comments v1: 38 pages, 8 figure

Cellular aspect ratio and cell division mechanics underlie the patterning of cell progeny in diverse mammalian epithelia.

Cell division is essential to expand, shape, and replenish epithelia. In the adult small intestine, cells from a common progenitor intermix with other lineages, whereas cell progeny in many other epithelia form contiguous patches. The mechanisms that generate these distinct patterns of progeny are poorly understood. Using light sheet and confocal imaging of intestinal organoids, we show that lineages intersperse during cytokinesis, when elongated interphase cells insert between apically displaced daughters. Reducing the cellular aspect ratio to minimize the height difference between interphase and mitotic cells disrupts interspersion, producing contiguous patches. Cellular aspect ratio is similarly a key parameter for division-coupled interspersion in the early mouse embryo, suggesting that this physical mechanism for patterning progeny may pertain to many mammalian epithelia. Our results reveal that the process of cytokinesis in elongated mammalian epithelia allows lineages to intermix and that cellular aspect ratio is a critical modulator of the progeny pattern

Contribution of Lianas to Plant Area Index and Canopy Structure in A Panamanian Forest

Lianas are an important component of tropical forests, where they reduce tree growth, fecundity, and survival. Competition for light from lianas may be intense; however, the amount of light that lianas intercept is poorly understood. We used a large-scale liana-removal experiment to quantify light interception by lianas in a Panamanian secondary forest. We measured the change in plant area index (PAI) and forest structure before and after cutting lianas (for 4 yr) in eight 80 m × 80 m plots and eight control plots (16 plots total). We used ground-based LiDAR to measure the 3-dimensional canopy structure before cutting lianas, and then annually for 2 yr afterwards. Six weeks after cutting lianas, mean plot PAI was 20% higher in control vs. liana removal plots. One yr after cutting lianas, mean plot PAI was ~17% higher in control plots. The differences between treatments diminished significantly 2 yr after liana cutting and, after 4 yr, trees had fully compensated for liana removal. Ground-based LiDAR revealed that lianas attenuated light in the upper- and middle-forest canopy layers, and not only in the upper canopy as was previously suspected. Thus, lianas compete with trees by intercepting light in the upper- and mid-canopy of this forest

Dispositivos tecnológicos para el estudiantado de la UNED

Esta ponencia muestra el trabajo realizado en el proyecto de investigación-acción Proyecto piloto de uso de dispositivos tecnológicos por parte de estudiantes de la UNED. Este proyecto estuvo a cargo del Laboratorio de fabricación, Kä Träre, y la Oficina de Atención Socioeconómica de la UNED. El proyecto concluirá a inicios de agosto de 2017, pero se tienen suficientes insumos para compartir con la comunidad. El proyecto consistió en entregar a 18 personas una tableta o un Raspberry Pi 3 como dispositivo tecnológico para sus labores académicas; con el fin de tener su valoración sobre el uso de estos dispositivos por la comunidad estudiantil; esto se realizó con personas sin equipo tecnológico y con nulas opciones de conseguirlo. Las respuestas fueron positivas

Análisis microbiológico de helados de base de leche, expendidos en la ciudad de Talca, Chile

79 p.Las toxiinfecciones alimentarias (TIA) constituyen un gran problema de salud pública a nivel mundial, siendo su causa el consumo de alimentos contaminados con una gran variedad de microorganismos, y también, por las toxinas producidas por el metabolismo de éstos. Por estas razones, se hace imprescindible desarrollar sistemas de vigilancia epidemiológica que permita establecer la prevalencia de los principales agentes etiológicos que contaminan los alimentos que consume la población, a fin de evitar brotes, tanto en comunidades colectivas, como en el medio familiar. Uno de los principales productos de consumo en época de verano corresponde a los helados de base de leche, los cuales, son un alimento de preferencia en un amplio rango de personas, de todas las edades y estratos sociales. En el presente estudio se realizó un análisis microbiológico de helados de base de leche según los estándares del Reglamento Sanitario de los alimentos, Decreto Supremo nº 977 Chileno. Para lograr dicho objetivo se realizó el análisis de Salmonella spp., Staphylococcus aureus y Coliformes Totales para un total de 100 muestras, todas obtenidas de locales de expendio de helados de la ciudad de Talca, Chile. Los protocolos de análisis microbiológico, corresponden a los establecidos por el Food and Drug Administration (FDA) en su Bacteriological Analytical Manual (BAM). Como resultado, se encontró una alta frecuencia de muestras que excedían los valores límites establecidos por la norma para Staphylococcus aureus y Coliformes Totales. No se aisló Salmonella spp. En base a estos resultados, la mitad los lotes analizados fueron rechazados en base a su calidad microbiológica

Mitigation needs adaptation: Tropical forestry and climate change

International audienceThe relationship between tropical forests and global climate change has so far focused on mitigation, while much less emphasis has been placed on how management activities may help forest ecosystems adapt to this change. This paper discusses how tropical forestry practices can contribute to maintaining or enhancing the adaptive capacity of natural and planted forests to global climate change and considers challenges and opportunities for the integration of tropical forest management in broader climate change adaptation. In addition to the use of reduced impact logging to maintain ecosystem integrity, other approaches may be needed, such as fire prevention and management, as well as specific silvicultural options aimed at facilitating genetic adaptation. In the case of planted forests, the normally higher intensity of management (with respect to natural forest) offers additional opportunities for implementing adaptation measures, at both industrial and smallholder levels. Although the integration in forest management of measures aimed at enhancing adaptation to climate change may not involve substantial additional effort with respect to current practice, little action appears to have been taken to date. Tropical foresters and forest-dependent communities appear not to appreciate the risks posed by climate change and, for those who are aware of them, practical guidance on how to respond is largely non-existent. The extent to which forestry research and national policies will promote and adopt management practices in order to assist production forests adapt to climate change is currently uncertain. Mainstreaming adaptation into national development and planning programs may represent an initial step towards the incorporation of climate change considerations into tropical forestry

Securin Is Not Required for Chromosomal Stability in Human Cells

Abnormalities of chromosome number are frequently observed in cancers. The mechanisms regulating chromosome segregation in human cells are therefore of great interest. Recently it has been reported that human cells without an hSecurin gene lose chromosomes at a high frequency. Here we show that, after hSecurin knockout through homologous recombination, chromosome losses are only a short, transient effect. After a few passages hSecurin(−/−) cells became chromosomally stable and executed mitoses normally. This was unexpected, as the securin loss resulted in a persisting reduction of the sister-separating protease separase and inefficient cleavage of the cohesin subunit Scc1. Our data demonstrate that securin is dispensable for chromosomal stability in human cells. We propose that human cells possess efficient mechanisms to compensate for the loss of genes involved in chromosome segregation

The role of tropical dry forests for biodiversity, carbon and water conservation in the neotropics: lessons learned and opportunities for its sustainable management

In this paper, we provide a comprehensive evaluation of the current regional literature associated with tropical dry forest (TDF) along three main axes: biodiversity, carbon and water conservation in the neotropics. Our analysis provides three key findings: (1) from the biodiversity point of view, we document that high degrees of endemism, diversity of plant life forms and ecophysiological types as key elements for their conservation across the Americas, (2) from the carbon storage point of view, we found that if the world’s TDFs were restored they whole ecosystem would comprise 22 Pg of carbon in aboveground biomass. In the Americas alone, TDF restoration could potentially add 8 Pg of carbon to the potential total ecosystem carbon stock, (3) we found that at least 66 % of water reservoirs in the neotropics are located within dry forest ecoregions; therefore, the conservation of the quality of freshwater sources for human consumption in the neotropics is directly dependent on the sustainable management of TDF-dominated landscapes. In this paper, we stress that advocacy for conservation and sustainable management of TDF will benefit from integrating it’s value in biophysical terms (e.g. carbon, biodiversity) with key ecosystem services and uses (e.g. its impact on hydrological dynamics and its potential for fostering ecotourism initiatives and entrepreneurship). By doing this, support and awareness could be wider and more effective in the long term, especially from national and local communities. © 2014, Springer-Verlag Berlin Heidelberg