Biodiversity shapes tree species aggregations in tropical forests

Spatial patterns of conspecific trees are considered as the consequences of biological interactions and environmental influences. They also reflect species interactions in plant communities. However, biological attributes are often neglected while deliberating the factors shaping species distributions. As rising attentions are paid to spatial patterns of tropical forest trees, we noticed that seven Center of Tropical Forest Sites and four Forest Dynamic Plots in Asia and America have presented analogously high proportions of species with aggregated conspecific individuals coincidently. This phenomenon is distinctive and repudiates fundamental ecology hypotheses which suggested dispersed distributions of conspecific tropical trees due to intensive density and natural enemy pressures in tropical forests. We believe that similar aggregation patterns shared by these tropical forests implies the existence of structuring forces in biogeographical scale instead of habitat heterogeneity in local community scales as scientists have considered. To approach the factors contributing to this cross-continent spatial pattern of trees, we obtained and reviewed ecosystem attributes, including topography, temperature, precipitation, biodiversity, density, and biomass, of these forests. Here we show that the proportions of aggregated species are actually constants independent of any ecosystem attributes regardless the nature of these tropical forests. However, local biodiversity are the major factor determining the number of aggregated species and the aggregation of large individuals of these forests. Aggregation of large trees declines along rising biodiversity, while the numbers of aggregated species increase permanently along lifting biodiversity. We propose a possible equilibrium and saturated status of the tropical forests in accommodating aggregated species. Furthermore, the tight correlations of biodiversity and species aggregation strongly imply the importance of overlooked biological interactions in shaping the spatial patterns in the tropical forests

Hospitalized Pediatric Parainfluenza Virus Infections in a Medical Center

Background/PurposeParainfluenza viruses (PIVs) are common pathogens in respiratory tract infections. The aims of this study were to determine the clinical presentation of PIV infections in hospitalized children and to identify particular clinical indications that may effectively distinguish between different PIV serotypes.MethodsA retrospective review of data from children hospitalized with PIV infections at the Mackay Memory Hospital in Taipei between January 2005 and December 2007 was undertaken. Symptoms, signs, laboratory findings and seasonal variations between different types of PIV (serotypes 1, 2 and 3) were compared.ResultsA total of 206 patients [119 (57.8%) boys and 87 (42.2%) girls] were enrolled in the study. Seventy-four (35.9%) patients were infected with PIV serotype 1, 25 (12.1%) with serotype 2 and 107 (51.9%) with serotype 3. The most common clinical presentations were fever (81.1%), cough (66.0%), rhinorrhea (44.2%) and hoarseness (22.3%); 4.9% of the infected children also had skin rashes. No significant differences were found in average white blood cell counts and C-reactive protein levels between the three serotypes. PIV serotype 1 infections were discernible throughout the year; serotype 2 tended to cluster in the late summer and autumn of 2005 and 2007; and serotype 3 was more common in the spring and early summer.ConclusionThe clinical presentation of PIV infection in hospitalized children ranges from upper respiratory tract infection to croup, bronchiolitis and viral bronchopneumonia, with the different types of PIV infections giving rise to similar symptoms. The seasonal distribution of the different serotypes is, nevertheless, quite distinct

Estimating quality weights for EQ-5D (EuroQol-5 dimensions) health states with the time trade-off method in Taiwan

Background/PurposeEQ-5D (EuroQol-5 dimensions) is a preference-based measure of health, which is widely used in cost–utility analyses. It has been suggested that each country should develop its own value set. We therefore sought to develop the quality weights of the EQ-5D health states with the time trade-off (TTO) method in Taiwan.MethodsA total of 745 respondents consisting of employees and volunteers in 17 different hospitals were recruited and interviewed. Each of them valued 13 of 73 EQ-5D health states using the TTO method. Based on the three exclusion criteria for valuation data, only 456 (61.21%) respondents were considered eligible for data analysis. The quality weights for all EQ-5D health states were modeled by generalized estimating equations (GEEs).ResultsOver half of the responses were given negative values, and the medical personnel seemed to have a significantly higher TTO value (+0.1) than others after controlling for other predictors. The N3 model (level 3 occurred within at least 1 dimension) yielded an acceptable fit for the observed OTT data [mean absolute error (MAE) = 0.056, R2 = 0.35]. The magnitude of mean absolute differences (MADs) between Taiwan data and those from the UK, Japan, and South Korea ranged from 0.146 to 0.592, but the rank correlation coefficients were all above 0.811.ConclusionThis study reaffirms the differences in health-related preference values across countries. The high proportion of negative values might indicate that we have also partially measured the intensity of fear in addition to the utility of different health states