| 1. |
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| 2. |
- Baltes, Peter, et al.
(författare)
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Small-bowel capsule endoscopy in patients with Meckel's diverticulum : clinical features, diagnostic workup, and findings. A European multicenter I-CARE study
- 2023
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Ingår i: Gastrointestinal Endoscopy. - : Elsevier BV. - 0016-5107. ; 97:5, s. 3-926
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aims: Meckel's diverticulum (MD) may remain silent or be associated with adverse events such as GI bleeding. The main aim of this study was to evaluate indicative small-bowel capsule endoscopy (SBCE) findings, and the secondary aim was to describe clinical presentation in patients with MD. Methods: This retrospective European multicenter study included patients with MD undergoing SBCE from 2001 until July 2021. Results: Sixty-nine patients with a confirmed MD were included. Median age was 32 years with a male-to-female ratio of approximately 3:1. GI bleeding or iron-deficiency anemia was present in nearly all patients. Mean hemoglobin was 7.63 ± 1.8 g/dL with a transfusion requirement of 52.2%. Typical capsule endoscopy (CE) findings were double lumen (n = 49 [71%]), visible entrance into the MD (n = 49 [71%]), mucosal webs (n = 30 [43.5%]), and bulges (n = 19 [27.5%]). Two or more of these findings were seen in 48 patients (69.6%). Ulcers were detected in 52.2% of patients (n = 36). In 63.8% of patients (n = 44), a combination of double lumen and visible entrance into the MD was evident, additionally revealing ulcers in 39.1% (n = 27). Mean percent SB (small bowel) transit time for the first indicative image of MD was 57% of the total SB transit time. Conclusions: Diagnosis of MD is rare and sometimes challenging, and a preoperative criterion standard does not exist. In SBCE, the most frequent findings were double-lumen sign and visible diverticular entrance, sometimes together with ulcers.
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| 3. |
- Ferrando, Carlos, et al.
(författare)
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Individualised, perioperative open-lung ventilation strategy during one-lung ventilation (iPROVE-OLV) : a multicentre, randomised, controlled clinical trial
- 2024
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Ingår i: The Lancet Respiratory Medicine. - : Elsevier. - 2213-2600 .- 2213-2619. ; 12:3, s. 195-206
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Tidskriftsartikel (refereegranskat)abstract
- Background It is uncertain whether individualisation of the perioperative open-lung approach (OLA) to ventilation reduces postoperative pulmonary complications in patients undergoing lung resection. We compared a perioperative individualised OLA (iOLA) ventilation strategy with standard lung-protective ventilation in patients undergoing thoracic surgery with one-lung ventilation. Methods This multicentre, randomised controlled trial enrolled patients scheduled for open or video-assisted thoracic surgery using one-lung ventilation in 25 participating hospitals in Spain, Italy, Turkey, Egypt, and Ecuador. Eligible adult patients (age >= 18 years) were randomly assigned to receive iOLA or standard lung-protective ventilation. Eligible patients (stratified by centre) were randomly assigned online by local principal investigators, with an allocation ratio of 1:1. Treatment with iOLA included an alveolar recruitment manoeuvre to 40 cm H2O of end-inspiratory pressure followed by individualised positive end-expiratory pressure (PEEP) titrated to best respiratory system compliance, and individualised postoperative respiratory support with high-flow oxygen therapy. Participants allocated to standard lungprotective ventilation received combined intraoperative 4 cm H2O of PEEP and postoperative conventional oxygen therapy. The primary outcome was a composite of severe postoperative pulmonary complications within the first 7 postoperative days, including atelectasis requiring bronchoscopy, severe respiratory failure, contralateral pneumothorax, early extubation failure (rescue with continuous positive airway pressure, non-invasive ventilation, invasive mechanical ventilation, or reintubation), acute respiratory distress syndrome, pulmonary infection, bronchopleural fistula, and pleural empyema. Due to trial setting, data obtained in the operating and postoperative rooms for routine monitoring were not blinded. At 24 h, data were acquired by an investigator blinded to group allocation. All analyses were performed on an intention-to-treat basis. This trial is registered with ClinicalTrials.gov, NCT03182062, and is complete. Findings Between Sept 11, 2018, and June 14, 2022, we enrolled 1380 patients, of whom 1308 eligible patients (670 [434 male, 233 female, and three with missing data] assigned to iOLA and 638 [395 male, 237 female, and six with missing data] to standard lung-protective ventilation) were included in the final analysis. The proportion of patients with the composite outcome of severe postoperative pulmonary complications within the first 7 postoperative days was lower in the iOLA group compared with the standard lung-protective ventilation group (40 [6%] vs 97 [15%], relative risk 0 center dot 39 [95% CI 0 center dot 28 to 0 center dot 56]), with an absolute risk difference of -9 center dot 23 (95% CI -12 center dot 55 to -5 center dot 92). Recruitment manoeuvre-related adverse events were reported in five patients. Interpretation Among patients subjected to lung resection under one-lung ventilation, iOLA was associated with a reduced risk of severe postoperative pulmonary complications when compared with conventional lung-protective ventilation. Funding Instituto de Salud Carlos III and the European Regional Development Funds. Copyright (c) 2023 Elsevier Ltd. All rights reserved.
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| 4. |
- Garcia-Rojas, L. M., et al.
(författare)
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Rendimiento de los productos de la descomposición térmica De la madera de eucalyptus saligna smith a diferentes alturas del fuste comercial
- 2009
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Ingår i: Revista Chapingo, Serie Ciencias Forestales y del Ambiente. - 0186-3231. ; 15:2, s. 147-154
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Tidskriftsartikel (refereegranskat)abstract
- In this work the qualitative and quantitative results of the thermal pyrolysis of Eucalyptus Saligna Smith is presented, to different heights of the commercial wooden log. The wood was collected from Pinar del Rio, Cuba. The need to use this wood like energy source in the region led to the research at laboratory scale. The used trees were 20 and 22 years old, from which 20 cm disks were cut at 25; 55 and 85 % height of the log, milled to chips and air dried. The chemical composition was determined and was carried out the previous analysis of the samples, as well as the thermal decomposition in micro scale. The study of products from the pyrolysis (coal and tar), it was made in a reactor of fixed channel. The caloric value of the biomass and its charcoal was determined. The influence of the height of the log in the product yields from the pyrolysis was studied.As significant differences was observed as for the chemical composition of the studied wood: cellulose, hemicelulose and lignine, being observed an apparent increase of the lignine percentage with the height of the tree. The previous analysis belongs together with the chemical composition of the studied biomass. A small decrease was observed in the yield of the coal and of the percentage of tars with the height of the tree, this belongs together with the variation of the chemical composition according to the height of the tree. The biggest yield of coal and caloric value was achieved at the lowest height of the tree. The contribution to gas goes increasing with the height.
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| 6. |
- Hülsmann, Lisa, et al.
(författare)
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Latitudinal patterns in stabilizing density dependence of forest communities
- 2024
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Ingår i: Nature. - 0028-0836 .- 1476-4687. ; 627, s. 564-571
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Tidskriftsartikel (refereegranskat)abstract
- Numerous studies have shown reduced performance in plants that are surrounded by neighbours of the same species1,2, a phenomenon known as conspecific negative density dependence (CNDD)3. A long-held ecological hypothesis posits that CNDD is more pronounced in tropical than in temperate forests4,5, which increases community stabilization, species coexistence and the diversity of local tree species6,7. Previous analyses supporting such a latitudinal gradient in CNDD8,9 have suffered from methodological limitations related to the use of static data10–12. Here we present a comprehensive assessment of latitudinal CNDD patterns using dynamic mortality data to estimate species-site-specific CNDD across 23 sites. Averaged across species, we found that stabilizing CNDD was present at all except one site, but that average stabilizingCNDD was not stronger toward the tropics. However, in tropical tree communities, rare and intermediate abundant species experienced stronger stabilizing CNDD than did common species. This pattern was absent in temperate forests, which suggests that CNDD influences species abundances more strongly in tropical forests than it does in temperate ones13. We also found that interspecific variation in CNDD, which might attenuate its stabilizing effect on species diversity14,15, was high but not significantly different across latitudes. Although the consequences of these patterns for latitudinal diversity gradients are difficult to evaluate, we speculate that a more effective regulation of population abundances could translate into greater stabilization of tropical tree communities and thus contribute to the high local diversity of tropical forests.
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| 7. |
- Leite, Melina de Souza, et al.
(författare)
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Major axes of variation in tree demography across global forests
- 2024
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Ingår i: Ecography. - 0906-7590 .- 1600-0587.
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Tidskriftsartikel (refereegranskat)abstract
- The future trajectory of global forests is closely intertwined with tree demography, and a major fundamental goal in ecology is to understand the key mechanisms governing spatio-temporal patterns in tree population dynamics. While previous research has made substantial progress in identifying the mechanisms individually, their relative importance among forests remains unclear mainly due to practical limitations. One approach to overcome these limitations is to group mechanisms according to their shared effects on the variability of tree vital rates and quantify patterns therein. We developed a conceptual and statistical framework (variance partitioning of Bayesian multilevel models) that attributes the variability in tree growth, mortality, and recruitment to variation in species, space, and time, and their interactions – categories we refer to as organising principles (OPs). We applied the framework to data from 21 forest plots covering more than 2.9 million trees of approximately 6500 species. We found that differences among species, the species OP, proved a major source of variability in tree vital rates, explaining 28–33% of demographic variance alone, and 14–17% in interaction with space, totalling 40–43%. Our results support the hypothesis that the range of vital rates is similar across global forests. However, the average variability among species declined with species richness, indicating that diverse forests featured smaller interspecific differences in vital rates. Moreover, decomposing the variance in vital rates into the proposed OPs showed the importance of unexplained variability, which includes individual variation, in tree demography. A focus on how demographic variance is organized in forests can facilitate the construction of more targeted models with clearer expectations of which covariates might drive a vital rate. This study therefore highlights the most promising avenues for future research, both in terms of understanding the relative contributions of groups of mechanisms to forest demography and diversity, and for improving projections of forest ecosystems.
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| 8. |
- Medina-Vega, José A., et al.
(författare)
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Tropical tree ectomycorrhiza are distributed independently of soil nutrients
- 2024
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Ingår i: Nature Ecology and Evolution. - 2397-334X. ; 8, s. 400-410
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Tidskriftsartikel (refereegranskat)abstract
- Mycorrhizae, a form of plant–fungal symbioses, mediate vegetation impacts on ecosystem functioning. Climatic effects on decomposition and soil quality are suggested to drive mycorrhizal distributions, with arbuscular mycorrhizal plants prevailing in low-latitude/high-soil-quality areas and ectomycorrhizal (EcM) plants in high-latitude/low-soil-quality areas. However, these generalizations, based on coarse-resolution data, obscure finer-scale variations and result in high uncertainties in the predicted distributions of mycorrhizal types and their drivers. Using data from 31 lowland tropical forests, both at a coarse scale (mean-plot-level data) and fine scale (20 × 20 metres from a subset of 16 sites), we demonstrate that the distribution and abundance of EcM-associated trees are independent of soil quality. Resource exchange differences among mycorrhizal partners, stemming from diverse evolutionary origins of mycorrhizal fungi, may decouple soil fertility from the advantage provided by mycorrhizal associations. Additionally, distinct historical biogeographies and diversification patterns have led to differences in forest composition and nutrient-acquisition strategies across three major tropical regions. Notably, Africa and Asia’s lowland tropical forests have abundant EcM trees, whereas they are relatively scarce in lowland neotropical forests. A greater understanding of the functional biology of mycorrhizal symbiosis is required, especially in the lowland tropics, to overcome biases from assuming similarity to temperate and boreal regions.
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| 9. |
- Piponiot, Camille, et al.
(författare)
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Distribution of biomass dynamics in relation to tree size in forests across the world
- 2022
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 234, s. 1664-1677
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Tidskriftsartikel (refereegranskat)abstract
- Tree size shapes forest carbon dynamics and determines how trees interact with their environment, including a changing climate. Here, we conduct the first global analysis of among-site differences in how aboveground biomass stocks and fluxes are distributed with tree size. We analyzed repeat tree censuses from 25 large-scale (4–52 ha) forest plots spanning a broad climatic range over five continents to characterize how aboveground biomass, woody productivity, and woody mortality vary with tree diameter. We examined how the median, dispersion, and skewness of these size-related distributions vary with mean annual temperature and precipitation. In warmer forests, aboveground biomass, woody productivity, and woody mortality were more broadly distributed with respect to tree size. In warmer and wetter forests, aboveground biomass and woody productivity were more right skewed, with a long tail towards large trees. Small trees (1–10 cm diameter) contributed more to productivity and mortality than to biomass, highlighting the importance of including these trees in analyses of forest dynamics. Our findings provide an improved characterization of climate-driven forest differences in the size structure of aboveground biomass and dynamics of that biomass, as well as refined benchmarks for capturing climate influences in vegetation demographic models.
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| 10. |
- Proenza Pérez, Nestor, et al.
(författare)
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Estudio termodinámico y dimensionamiento de un gasificador downdraft para um sistema de cogeneración compacto en comunidades aisladas
- 2006
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Ingår i: Revista Ciências Exatas. - 1516-2893. ; 12:1, s. 53-62
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Tidskriftsartikel (refereegranskat)abstract
- The gasification system has been used for manyyears ago. It has demonstrated a good way for to solveenergetic problems for isolated communities. In thispaper, is studied the gasification system associated tointernal combustion engine. Are considered technicaland economical aspects for the system design forapplications in rural localities where the electricityenergy is not possible since economical and socialviewpoint. In this manner social contribution andeconomical benefits can be determinated.
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| 11. |
- Zuleta, Daniel, 1990, et al.
(författare)
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Damage to living trees contributes to almost half of the biomass losses in tropical forests
- 2023
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 29, s. 3409-3420
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Tidskriftsartikel (refereegranskat)abstract
- Accurate estimates of forest biomass stocks and fluxes are needed to quantify global carbon budgets and assess the response of forests to climate change. However, most forest inventories consider tree mortality as the only aboveground biomass (AGB) loss without accounting for losses via damage to living trees: branchfall, trunk breakage, and wood decay. Here, we use ~151,000 annual records of tree survival and structural completeness to compare AGB loss via damage to living trees to total AGB loss (mortality + damage) in seven tropical forests widely distributed across environmental conditions. We find that 42% (3.62 Mg ha−1 year−1; 95% confidence interval [CI] 2.36–5.25) of total AGB loss (8.72 Mg ha−1 year−1; CI 5.57–12.86) is due to damage to living trees. Total AGB loss was highly variable among forests, but these differences were mainly caused by site variability in damage-related AGB losses rather than by mortality-related AGB losses. We show that conventional forest inventories overestimate stand-level AGB stocks by 4% (1%–17% range across forests) because assume structurally complete trees, underestimate total AGB loss by 29% (6%–57% range across forests) due to overlooked damage-related AGB losses, and overestimate AGB loss via mortality by 22% (7%–80% range across forests) because of the assumption that trees are undamaged before dying. Our results indicate that forest carbon fluxes are higher than previously thought. Damage on living trees is an underappreciated component of the forest carbon cycle that is likely to become even more important as the frequency and severity of forest disturbances increase.
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| 12. |
- Zuleta, Daniel, 1990, et al.
(författare)
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Individual tree damage dominates mortality risk factors across six tropical forests
- 2022
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Ingår i: New Phytologist. - : Wiley. - 0028-646X .- 1469-8137. ; 233, s. 705-721
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Tidskriftsartikel (refereegranskat)abstract
- The relative importance of tree mortality risk factors remains unknown, especially in diverse tropical forests where species may vary widely in their responses to particular conditions. We present a new framework for quantifying the importance of mortality risk factors and apply it to compare 19 risks on 31 203 trees (1977 species) in 14 one-year periods in six tropical forests. We defined a condition as a risk factor for a species if it was associated with at least a doubling of mortality rate in univariate analyses. For each risk, we estimated prevalence (frequency), lethality (difference in mortality between trees with and without the risk) and impact (‘excess mortality’ associated with the risk, relative to stand-level mortality). The most impactful risk factors were light limitation and crown/trunk loss; the most prevalent were light limitation and small size; the most lethal were leaf damage and wounds. Modes of death (standing, broken and uprooted) had limited links with previous conditions and mortality risk factors. We provide the first ranking of importance of tree-level mortality risk factors in tropical forests. Future research should focus on the links between these risks, their climatic drivers and the physiological processes to enable mechanistic predictions of future tree mortality.
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