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- Bernal, Ximena E., et al.
(författare)
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Empowering Latina scientists
- 2019
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 363:6429, s. 825-826
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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- Gómez-Correa, Luisa F., et al.
(författare)
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Canopy tree mortality depends on the proportion of crown exposed to sunlight, but this effect varies with species' wood density
- 2023
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Ingår i: Biotropica. - 0006-3606 .- 1744-7429. ; 55, s. 1136-1147
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Tidskriftsartikel (refereegranskat)abstract
- Understanding what drives changes in tree mortality as well as the covariates influencing trees' response is a research priority to predict forest responses to global change. Here, we combined drone photogrammetry and ground-based data to assess the influence of crown exposure to light (relative to total crown area), growth deviations (relative to conspecifics), tree size, and species' wood density (as a surrogate for light-demanding and shade-tolerant life-history strategies) on the mortality of 984 canopy trees in an Amazon terra firme forest. Trees with lower wood density were less prone to die when their proportion of crown was more exposed to sunlight, but this relationship with relative crown exposure weakened and slightly reversed as wood density increased. Trees growing less than their species average had higher mortality, especially when the species' wood density decreased. The role of wood density in determining the survival of canopy trees under varying light conditions indicates differential responses of light-demanding versus shade-tolerant species. Our results highlight the importance of accounting for life-history strategies, via plant functional types, in vegetation dynamic models aiming to predict forest demography under a rapidly changing climate. Abstract in Spanish is available with online material.
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- Orkisz, Maciej, et al.
(författare)
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Voxel-wise assessment of lung aeration changes on CT images using image registration: a : application to acute respiratory distress syndrome (ARDS)
- 2019
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Ingår i: International Journal of Computer Assisted Radiology and Surgery. - : Springer Science and Business Media LLC. - 1861-6410 .- 1861-6429. ; , s. 1-9
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Tidskriftsartikel (refereegranskat)abstract
- Purpose(1) To improve the accuracy of global and regional alveolar-recruitment quantification in CT scan pairs by accounting for lung-tissue displacements and deformation, (2) To propose a method for local-recruitment calculation.MethodsRecruitment was calculated by subtracting the quantity of non-aerated lung tissues between expiration and inspiration. To assess global recruitment, lung boundaries were first interactively delineated at inspiration, and then they were warped based on automatic image registration to define the boundaries at expiration. To calculate regional recruitment, the lung mask defined at inspiration was cut into pieces, and these were also warped to encompass the same tissues at expiration. Local-recruitment map was calculated as follows: For each voxel at expiration, the matching location at inspiration was determined by image registration, non-aerated voxels were counted in the neighborhood of the respective locations, and the voxel count difference was normalized by the neighborhood size. The methods were evaluated on 120 image pairs of 12 pigs with experimental acute respiratory distress syndrome.ResultsThe dispersion of global- and regional-recruitment values decreased when using image registration, compared to the conventional approach neglecting tissue motion. Local-recruitment maps overlaid onto the original images were visually consistent, and the sum of these values over the whole lungs was very close to the global-recruitment estimate, except four outliers.ConclusionsImage registration can compensate lung-tissue displacements and deformation, thus improving the quantification of alveolar recruitment. Local-recruitment calculation can also benefit from image registration, and its values can be overlaid onto the original image to display a local-recruitment map. They also can be integrated over arbitrarily shaped regions to assess regional or global recruitment.
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- Pulgarín-R, Paulo C., et al.
(författare)
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Migratory birds as vehicles for parasite dispersal? Infection by avian haemosporidians over the year and throughout the range of a long-distance migrant
- 2019
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Ingår i: Journal of Biogeography. - : Wiley. - 0305-0270 .- 1365-2699. ; 46:1, s. 83-96
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Tidskriftsartikel (refereegranskat)abstract
- Aim: The role of migratory birds in the spread of parasites is poorly known, in part because migratory strategies and behaviours potentially affecting transmission are not easy to study. We investigated the dynamics of infection by blood parasites through the annual cycle of a long-distance Nearctic–Neotropical migratory songbird to examine the role of this species in dispersing parasites between continents. Location: The Americas. Taxon: Grey-cheeked Thrush (Catharus minimus, Aves, Passeriformes, Turdidae), Birds. Methods: We used molecular and microscopy screening of haemosporidian parasites (Plasmodium, Haemoproteus, and Leucocytozoon) to examine the prevalence, distribution, and diversity of lineages through the annual cycle (breeding, migration, and wintering) of the grey-cheeked thrush in North and Central America, Santa Marta mountains, the Andes, and the Amazon. We aimed to identify transmission areas, to examine the degree of sharing of haemosporidian lineages with resident birds in various areas and to assess the potential role of immunologically naïve juvenile individuals in parasite transmission. Results: Prevalence and lineage diversity of haemosporidians varied significantly over time, being higher during breeding and fall and spring migration, and declining during wintering. Grey-cheeked thrush shared few parasite lineages with tropical resident birds and slightly more lineages with other migratory and resident boreal species. We detected gametocytes in blood during spring migration stopover, but these were of lineages not found in resident tropical birds, indicating relapses of parasites transmitted elsewhere. Transmission likely occurs mostly on the breeding grounds, where juveniles and adults carried lineages restricted to closely related species of thrushes and other species of boreal birds. Main conclusions: Long-distance migratory songbirds are likely not important dispersers of blood parasites because there are ecological and evolutionary barriers to the interchange of parasites across vastly separated areas. Further work with thorough spatial and temporal sampling across other species, and considering the role of vectors, is necessary to understand the ecological and evolutionary factors explaining the distribution of parasites over broad scales.
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- Ramirez, Angie, et al.
(författare)
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Biotribological behavior of Ti6Al4V alloy fabricated by EBM and subsequently anodized
- 2022
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Ingår i: Proceedings. - 9786289528718 ; , s. 404-410
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Konferensbidrag (refereegranskat)abstract
- Hip joints can be damaged by metabolic (degenerative disease) or mechanical (fracture) causes, limiting their functioning. To restore joint movement, the joint must be replaced by a hip prosthesis. Lubrication, friction and wear phenomena occur in the joints, which, in turn, are often responsible for the failure of the prosthesis, causing its loosening. The aim of the present study is to evaluate the biotribological behavior of a prototype Ti6Al4V hip prosthesis made-up by electron beam melting (EBM) additive manufacturing and subsequently surface modified by anodizing. Once the prototype was obtained, some samples were polished for biotribological tests and others for anodizing. The biotribological tests were performed in a ball-ondisk tribometer using 6 mm diameter alumina counterbodies. Wear tracks of 2 mm in diameter were obtained, using SBF solution at a temperature of 37 °C as the medium. The samples fabricated by EBM and subsequently anodized showed the highest values of friction coefficients, while the samples madeup by forging and EBM showed similar friction coefficients, while the anodized samples showed the lowest wear rate followed by the samples manufactured by EBM.
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