Spatial aggregation patterns in four mistletoe species: ecological and environmental determinants.

Plant spatial distribution is an important topic in ecology as it determines species coexistence and biodiversity dynamics. Usually, plants show clustered distributions in nature. Mistletoes are a good example of aggregated distributions, as they form dense aggregations due to several factors (availability of competent hosts, seed dispersal vectors, microclimate conditions). We analysed four native mistletoe species with divergent life histories and host ranges: Desmaria mutabilis and Tristerix corymbosus from the temperate rainforests of southern Chile; and Tristerix aphyllus and Tristerix verticillatus from the northern semi-desert zone. While T. corymbosus and T. verticillatus have a wide host range, T. aphyllus and D. mutabilis are specialists that can parasitize only a few plant species. We hypothesized that specialized species would be more aggregated due to ecological and environmental restrictions. We used heterogeneous Poisson models to quantify spatial aggregation. Three of the four mistletoe species were spatially clustered at both environments, with aggregation being stronger in the temperate rainforest of southern Chile and particularly in the host-specialist species. Our results suggest that environmental constraints are more important than ecological constraints (host range) in shaping mistletoe spatial structure. Mistletoe aggregated spatial distribution depends primarily on the environment that they inhabit, which conditions host spatial availability, and arrangement.

Examining factors for the adoption of silvopastoral agroforestry in the Colombian Amazon.

Current land use systems in the Amazon largely consist of extensive conventional productivist livestock operations that drive deforestation. Silvopastoral systems (SPS) support a transition to low carbon production if they intensify in sympathy with the needs of biophysical and socio-economic contexts. SPS have been promoted for decades as an alternative livestock production system but widespread uptake has yet to be seen. We provide a schema of associating factors for adoption of SPS based on past literature in tropical agriculture and apply this to a bespoke survey of 172 farms in the Caquetá region of the Colombian Amazon. We find a number of factors which do not apply to this region and argue for a context specific approach. The impact of managing increased market access and opportunities for SPS producers are crucial to avoiding additional deforestation. Further understanding of the underlying antecedents of common factors, such as perceptions of silvopastoral systems, would reduce the risk of perverse policy outcomes.

Measurement of 2D density profiles using a second-harmonic, dispersion interferometer.

A second-harmonic, dispersion interferometer is used to image large-area (≃5 cm2) plasma-jet and gas-jet density profiles. Achromatic telescopes magnify the diameters of the primary-laser beam (1064 nm) and its second-harmonic (532 nm) before probing the sample and de-magnify the beam diameters after the sample, where the primary beam transfers its phase change to a second, second-harmonic beam, allowing the sample's dispersive-phase change to be measured between two, orthogonally polarized second harmonic beams. The telescopes produce an azimuthally symmetric, dispersive-phase shift in the sample + background phase-change image and in the background phase-change image, which is removed by digital subtraction. The interferometer's performance was verified using standard-optical components as dispersive elements (BK7 lenses and wedge plates), resolving a minimum, phase-change sensitivity of Δϕmin ≳ 15 mrad and spatial resolution of Δxres ≃ 100 µm. The phase change produced by unknown-density objects (a pulsed-plasma-jet and a pulsed-gas-jet) was measured, and their data were used to recover the original, 2D density profiles using an inverse Abel transform: peak-number density, Ngas ≃ 6 × 1020 cm-3 and Ne ≃ 5 × 1016 cm-3; line-integrated density, ∫Ngasdl ∼ 2 × 1019cm-2 and ∫Nedl ∼ 1 × 1016cm-2. The techniques and methods developed here are scalable to even larger probe-beam diameters and frame-capture rates, leading to a diagnostic capability that is well-suited for applications involving the real-time measurement of density.

Diaphragm pacing in a pediatric patient with Acquired Central Hypoventilation syndrome. / Marcapasos diafragmático en paciente pediátrico con síndrome de Hipoventilación Central Adquirido.

INTRODUCTION: Diaphragmatic pacemaker is a device that reduces or eliminates the need of mechanical ventilation in patients with chronic respiratory failure who keep the phrenic nerve-diaphragm axis intact, as long as they do not present intrinsic lung disease. Although its implantation has been practiced for deca des, its use is not widespread and to date, there is little published literature about it, mostly related to high spinal cord injury and congenital central hypoventilation syndrome. OBJECTIVE: To describe an experience of diaphragmatic pacemaker implantation in a pediatric patient with acquired cen tral hypoventilation syndrome. CLINICAL CASE: Female patient with central hypoventilation syndrome secondary to ischemic brainstem lesion as a result of ventriculoperitoneal shunt malfunction. For this reason, for 5 years she was supported by inpatient mechanical ventilation. At 7 years of age, a diaphragmatic pacemaker was implanted by thoracoscopic surgery, which allowed, after a period of rehabilitation and respiratory conditioning, mechanical ventilation withdrawal, and hospital dischar ge. CONCLUSIONS: Diaphragmatic pacemaker is a feasible, potentially safe, and cost-effective option for decreasing or eliminating mechanical ventilation dependence and improve life quality in patients with acquired central hypoventilation syndrome.

Marcapasos diafragmático en paciente pediátrico con síndrome de Hipoventilación Central Adquirido / Diaphragm pacing in a pediatric patient with Acquired Central Hypoventilation syndrome

Resumen: Introducción: El marcapasos diafragmático permite reducir o eliminar la necesidad de ventilación mecánica en pacientes con insuficiencia respiratoria crónica que conservan el eje nervio frénico-diafragma in tacto, siempre que no presenten enfermedad pulmonar intrínseca. Aunque su implantación ha sido practicada por décadas, su uso no está ampliamente difundido, y existe poca literatura pu blicada al respecto, la mayoría relacionada con lesión medular alta y síndrome de hipoventilación central congénito. Objetivo: Describir una experiencia de implantación de marcapasos diafragmático en paciente pediátrico con síndrome de hipoventilación central adquirido. Caso Clínico: Pa ciente femenino con síndrome de hipoventilación central secundario a lesión isquémica de tronco cerebral como resultado de disfunción de válvula de derivación ventrículo peritoneal, motivo por el cual durante 5 años se mantuvo con asistencia de ventilación mecánica intrahospitalaria. A los 7 años de edad se implantó marcapasos diafragmático mediante cirugía toracoscópica, lo que per mitió posterior a un periodo de rehabilitación y acondicionamiento respiratorio el destete de la ventilación mecánica y el egreso hospitalario. Conclusiones: El marcapasos diafragmático es una opción factible, potencialmente segura y costo efectiva para disminuir o eliminar la dependencia de ventilación mecánica y mejorar la calidad de vida en pacientes con síndrome de hipoventilación central adquirido.

Abstract: Introduction: Diaphragmatic pacemaker is a device that reduces or eliminates the need of mechanical ventilation in patients with chronic respiratory failure who keep the phrenic nerve-diaphragm axis intact, as long as they do not present intrinsic lung disease. Although its implantation has been practiced for deca des, its use is not widespread and to date, there is little published literature about it, mostly related to high spinal cord injury and congenital central hypoventilation syndrome. Objective: To describe an experience of diaphragmatic pacemaker implantation in a pediatric patient with acquired cen tral hypoventilation syndrome. Clinical Case: Female patient with central hypoventilation syndrome secondary to ischemic brainstem lesion as a result of ventriculoperitoneal shunt malfunction. For this reason, for 5 years she was supported by inpatient mechanical ventilation. At 7 years of age, a diaphragmatic pacemaker was implanted by thoracoscopic surgery, which allowed, after a period of rehabilitation and respiratory conditioning, mechanical ventilation withdrawal, and hospital dischar ge. Conclusions: Diaphragmatic pacemaker is a feasible, potentially safe, and cost-effective option for decreasing or eliminating mechanical ventilation dependence and improve life quality in patients with acquired central hypoventilation syndrome.

Diversity of bacterial endophytes in roots of Mexican husk tomato plants (Physalis ixocarpa) and their detection in the rhizosphere.

Endophytic bacterial diversity was estimated in Mexican husk tomato plant roots by amplified rDNA restriction analysis and sequence homology comparison of the 16S rDNA genes. Sixteen operational taxonomic units from the 16S rDNA root library were identified based on sequence analysis, including the classes Gammaproteobacteria, Betaproteobacteria, Actinobacteria, and Bacilli. The predominant genera were Stenotrophomonas (21.9%), Microbacterium (17.1%), Burkholderia (14.3%), Bacillus (14.3%), and Pseudomonas (10.5%). In a 16S rDNA gene library of the same plant species' rhizosphere, only common soil bacteria, including Stenotrophomonas, Burkholderia, Bacillus, and Pseudomonas, were detected. We suggest that the endophytic bacterial diversity within the roots of Mexican husk tomato plants is a subset of the rhizosphere bacterial population, dominated by a few genera.