19 research outputs found

    Stand Characteristics and Leaf Litter Composition of a Dry Forest Hectare in Santa Rosa National Park, Costa Rica

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    One hectare of tropical dry forest in Guanacaste Conservation Area, Costa Rica was mapped and all trees larger than 10 cm diameter at breast height (DBH) identified. The same hectare was sampled for leaf litter and the two data sets, forest and litter, were compared. Dominant and subdominant species of the forest are represented in the leaf litter, whereas rare tree species are highly variable in their representation in the leaf litter. Relative abundance of dominant and subdominant tree species is represented well by the litter although absolute rank-order is nor identical between source forest basal area and leaf litter mass. The litter adds a significant component to the source forest data owing to the presence of vines and lianas, and more rarely small trees or shrubs. This indicates that litter studies may be able to add depth to forest diversity surveys. The source forest also was used to test foliar physiognomic reconstructions of climate that have been proposed recently by paleobotanists as an alternative to taxonomic affinities methods. The observed climate of the area does not conform to the climatic values that were predicted by application of these new methods. RESUMEN Una hectÁrea de bosque seco tropical en el Area de ConservaciÓn de Guanacaste, Costa Rica fue mapeada, y todos los Árboles mayores de 10 cm de dap fueron identificados. En la misma hectÁrea, se tomaron muestras de hojarasca y los dos colecciones de datos. bosque y hojarasca, fueron comparadas. Se encontrÓ que las especies dominantes y subdominantes del bosque estaban representadas en las muestras de hojarasca, mientras que la presencia de especias arbÓreas raras en las muestras de mojarasca fue muy variable. La abundancia relativa de especies arbÓreas dominantesestÁ bien representada en la hojarasca aunque el Área basal del bosque de origen y la masa de hojarasca no heron idÉnticos en rangos absolutos. La hojarasca aÑade un componente significativo a los datos del bosque de origen debido a la presencia de bejucos y lianas en la hojarasca, y mÁs raramente Árboles pequeÑos y arbustos. Estos datos indican que los estudios de hojarasca pueden incrementar la precisiÓn de las estimaciones de la diversidad de los bosques. El bosque de origen fue usado tarnbien para examinar reconstrucciones del clima basados en la fisiognomia foliar recientemenre propuesras por paleobotÁnicas como una alternativa a mÉtodos de afinidad raxonÓmicas. El clima observado en el Área no corresponde con los valores climÁticos que fueron predecidos por la aplicaciÓn de estos nuevos mÉtodos.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73234/1/j.1744-7429.1997.tb00034.x.pd

    Tagless tolling using DSRC for intelligent transport system: an interference study

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    Modern electronic tolling systems consists of on board units (OBUs) or tags that are carried in a vehicles and has a unique code that is used to identify a customer account. The wireless communications between the on-board unit or tag and road side unit is the most critical function. The DSRC communication technology intended for vehicle safety applications in Intelligent Transport Systems which can be used for applications such as tolling and is expected to be integrated into all new vehicles manufactured in the future. A design for tagless tolling system using DSRC to communicate with an OBU instead of tags is presented in this report. Analysis of the wireless signal propagation at 5.9GHz for a model of a 4 lane tolling point is completed using a simulation in MATLAB. The Signal-to-Interference ratio is used to characterise the quality of the wireless channel under shadowing. Results of the simulation show that co -channel interference from communications in adjacent lanes is a significant problem especially in multi lane free flow tolling points. Outage probability calculations show a small communications zone close to the gantry that can be used to complete the tolling transactions

    Gluteal lymphoedema associated with lower extremity lymphoedema : A preliminary study with indocyanine green lymphography and magnetic resonance imaging

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    Introduction: Indocyanine green (ICG) lymphography studies have identified that one in three to five patients with cancer-related lower extremity lymphoedema (LEL) demonstrated dermal backflow extending to the gluteal region. This study aimed to further characterize gluteal lymphoedema using contemporaneous magnetic resonance imaging (MRI). Patients and methods: Twenty-eight patients with unilateral advanced LEL who underwent both ICG lymphography and MRI prior to any surgical procedure were included in this study. The patients were divided into two groups with/without gluteal lymphoedema by the presence of dermal backflow on ICG lymphography. MRI was used to evaluate tissue changes. Results: Ten patients demonstrated gluteal lymphoedema on ICG lymphography and had a higher incidence of skin hypertrophy in the gluteal region. However, no difference in excess leg volume was found between the two groups. A trend of increasing gluteal subcutaneous tissue in the affected side was identified in patients with gluteal lymphoedema with a median increase of 20% compared with an 11% increase in the non-gluteal lymphoedema group. The excess gluteal subcutaneous tissue was positively correlated to ipsilateral excess leg volume. Conclusion: The gluteal lymphoedema group on ICG lymphography had skin thickening in the gluteal region and was likely identified in the secondary cancer-related group. Surgical and conservative management options for gluteal lymphoedema need to be considered in advanced LEL
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