El ocaso de pseudaechmea (bromeliaceae: bromelioideae)

Se propone y se discute la inclusión del género monotípico Pseudaechmea dentrode Billbergia (Bromeliaceae: Bromelioideae). Además, se presenta la combinaciónrespectiva, la ilustración y la redescripción morfológica de Billbergia ambigua(L. B. Sm. and amp; R. W. Read) Betancur and amp; N. R. Salinas, especie conocida sólo deldepartamento de Antioquia, Colombia

Confounding-adjustment methods for the causal difference in medians

Background With continuous outcomes, the average causal effect is typically defined using a contrast of expected potential outcomes. However, in the presence of skewed outcome data, the expectation (population mean) may no longer be meaningful. In practice the typical approach is to continue defining the estimand this way or transform the outcome to obtain a more symmetric distribution, although neither approach may be entirely satisfactory. Alternatively the causal effect can be redefined as a contrast of median potential outcomes, yet discussion of confounding-adjustment methods to estimate the causal difference in medians is limited. In this study we described and compared confounding-adjustment methods to address this gap. Methods The methods considered were multivariable quantile regression, an inverse probability weighted (IPW) estimator, weighted quantile regression (another form of IPW) and two little-known implementations of g-computation for this problem. Methods were evaluated within a simulation study under varying degrees of skewness in the outcome and applied to an empirical study using data from the Longitudinal Study of Australian Children. Results Simulation results indicated the IPW estimator, weighted quantile regression and g-computation implementations minimised bias across all settings when the relevant models were correctly specified, with g-computation additionally minimising the variance. Multivariable quantile regression, which relies on a constant-effect assumption, consistently yielded biased results. Application to the empirical study illustrated the practical value of these methods. Conclusion The presented methods provide appealing avenues for estimating the causal difference in medians.Peer reviewe

Use of Transient Time Response as a Measure to Characterize Phononic Crystal Sensors

Phononic crystals are periodic composite structures with specific resonant features that are gaining popularity in the field as liquid sensors. The introduction of a structural defect in an otherwise periodic regular arrangement can generate a resonant mode, also called defect mode, inside the characteristic band gaps of phononic crystals. The morphology, as well as the frequency in which these defect modes appear, can give useful information on the composition and properties of an analyte. Currently, only gain and frequency measurements are performed using phononic crystal sensors. Other measurements like the transient response have been implemented in resonant sensors such as quartz microbalances showing great results and proving to be a great complimentary measure to the gain and frequency measurements. In the present paper, a study of the feasibility of using the transient response as a measure to acquire additional information about the analyte is presented. Theoretical studies using the transmission line model were realized to show the impact of variations in the concentration of an analyte, in this case, lithium carbonate solutions, in the transient time of the system. Experimental realizations were also performed showing that the proposed measurement scheme presents significant changes in the resulting data, indicating the potential use of this measure in phononic crystal sensors. This proposed measure could be implemented as a stand-alone measure or as a compliment to current sensing modalities

Una nueva especie de costus (costaceae) de la amazonia colombiana

Se describe e ilustra Costus fissicalyx N. R. Salinas, Clavijo and amp; Betancur, una especienueva del sudeste de la Amazonia colombiana; además, se presenta información sobresus relaciones taxonómicas, distribución y hábitat. Costus fissicalyx se diferencia delas otras especies del género principalmente por la forma y el tipo de crecimientodel cáli

Herbivory promotes dental disparification and macroevolutionary dynamics in grunters (teleostei: Terapontidae), a freshwater adaptive radiation

Trophic shifts into new adaptive zones have played major (although often conflicting) roles in reshaping the evolutionary trajectories of many lineages. We analyze data on diet, tooth, and oral morphology and relate these traits to phenotypic disparification and lineage diversification rates across the ecologically diverse Terapontidae, a family of Australasian fishes. In contrast to carnivores and most omnivores, which have retained relatively simple, ancestral caniniform tooth shapes, herbivorous terapontids appear to have evolved a variety of novel tooth shapes at significantly faster rates to meet the demands of plant-based diets. The evolution of herbivory prompted major disparification, significantly expanding the terapontid adaptive phenotypic continuum into an entirely novel functional morphospace. There was minimal support for our hypothesis of faster overall rates of integrated tooth shape, spacing, and jaw biomechanical evolution in herbivorous terapontids in their entirety, compared with other trophic strategies. There was, however, considerable support for accelerated disparification within a diverse freshwater clade containing a range of specialized freshwater herbivores. While the evolutionary transition to herbivorous diets has played a central role in terapontid phenotypic diversification by pushing herbivores toward novel fitness peaks, there was little support for herbivory driving significantly higher lineage diversification compared with background rates across the family

Las ericáceas de la vertiente pacífica de nariño, colombia

Se realizó el tratamiento taxonómico de la familia Ericaceae para la vertiente pacífica del departamento de Nariño, Colombia. El área de estudio abarca toda la llanura del pacífico y la vertiente pacífica de la cordillera de los Andes, hasta los 2.000 m de altitud, de dicho departamento. Los registros de las especies se obtuvieron mediante trabajo de campo, revisión de literatura y el estudio de las colecciones depositadas en los  herbarios CAUP, COL, HUA, PSO, QCA y QCNE. En el tratamiento taxonómico se incluyen descripciones morfológicas para la familia Ericaceae y para cada uno de los géneros y especies, acompañadas de comentarios sobre su distribución geográfica y altitudinal, y en algunos casos, de comentarios taxonómicos. También se incluye una clave sinóptica y una clave dicotómica para determinar especies, un glosario de los términos botánicos utilizados y un listado de los especímenes citados. Se encontraron 53 especies, agrupadas en 11 géneros, de las cuales una es una especie nueva de Vaccinium para la ciencia, tres son nuevos registros para Colombia (Cavendishia awa, Psammisia chionantha y P. oreogenes), antes registradas solo para el norte del Ecuador, y 15 son nuevos registros para el departamento de Nariño (Anthopterus oliganthus, Cavendishia awa, C. palustris, Diogenesia floribunda,  Disterigma humboldtii, D. pseudokillipiella, Psammisia chionantha, P. dolichopoda, P. oreogenes, P. ulbrichiana, Sphyrospermum buxifolium, S. dissimile, S. distichum, Themistoclesia alata y Thibaudia archeri). Los géneros con más especies fueron Cavendishia (15), Psammisia (10), Disterigma (6) y Sphyrospermum (7), seguidos por Thibaudia con cuatro especies, Anthopterus y Macleania con tres especies, Diogenesia con dos especies y Satyria, Themistoclesia y Vaccinium con una especie. Por otra parte, nueve especies tienen distribución geográfica muy restringida, de las cuales tres solo han sido registradas para el área de estudio (Cavendishia oligantha, Diogenesia alstoniana y Vaccinium sp. nov.) y las seis restantes son compartidas con la región  limítrofe del norte del Ecuador. Tres especies (Cavendishia callista, Disterigma pseudokillipiella y Macleania smithiana) fueron exclusivas de la llanura del Pacífico (por debajo de 500 m de altitud), 31 especies de la región Andina (por encima de 500 m de altitud) y 19 se compartieron entre ambas regiones.La mayor riqueza de especies y endemismos se presentó entre 1.000 y 1.600 m de altitud, con 45 especies. Los resultados obtenidos muestran que la vertiente pacífica del departamento de Nariño, Colombia, es la región de América con mayor número de especies de ericáceas por unidad de área