Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 360
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Nature ; 625(7996): 728-734, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38200314

RESUMO

Trees structure the Earth's most biodiverse ecosystem, tropical forests. The vast number of tree species presents a formidable challenge to understanding these forests, including their response to environmental change, as very little is known about most tropical tree species. A focus on the common species may circumvent this challenge. Here we investigate abundance patterns of common tree species using inventory data on 1,003,805 trees with trunk diameters of at least 10 cm across 1,568 locations1-6 in closed-canopy, structurally intact old-growth tropical forests in Africa, Amazonia and Southeast Asia. We estimate that 2.2%, 2.2% and 2.3% of species comprise 50% of the tropical trees in these regions, respectively. Extrapolating across all closed-canopy tropical forests, we estimate that just 1,053 species comprise half of Earth's 800 billion tropical trees with trunk diameters of at least 10 cm. Despite differing biogeographic, climatic and anthropogenic histories7, we find notably consistent patterns of common species and species abundance distributions across the continents. This suggests that fundamental mechanisms of tree community assembly may apply to all tropical forests. Resampling analyses show that the most common species are likely to belong to a manageable list of known species, enabling targeted efforts to understand their ecology. Although they do not detract from the importance of rare species, our results open new opportunities to understand the world's most diverse forests, including modelling their response to environmental change, by focusing on the common species that constitute the majority of their trees.


Assuntos
Florestas , Árvores , Clima Tropical , Biodiversidade , Árvores/anatomia & histologia , Árvores/classificação , Árvores/crescimento & desenvolvimento , África , Sudeste Asiático
2.
Nature ; 596(7873): 536-542, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34433947

RESUMO

Tropical forests store 40-50 per cent of terrestrial vegetation carbon1. However, spatial variations in aboveground live tree biomass carbon (AGC) stocks remain poorly understood, in particular in tropical montane forests2. Owing to climatic and soil changes with increasing elevation3, AGC stocks are lower in tropical montane forests compared with lowland forests2. Here we assemble and analyse a dataset of structurally intact old-growth forests (AfriMont) spanning 44 montane sites in 12 African countries. We find that montane sites in the AfriMont plot network have a mean AGC stock of 149.4 megagrams of carbon per hectare (95% confidence interval 137.1-164.2), which is comparable to lowland forests in the African Tropical Rainforest Observation Network4 and about 70 per cent and 32 per cent higher than averages from plot networks in montane2,5,6 and lowland7 forests in the Neotropics, respectively. Notably, our results are two-thirds higher than the Intergovernmental Panel on Climate Change default values for these forests in Africa8. We find that the low stem density and high abundance of large trees of African lowland forests4 is mirrored in the montane forests sampled. This carbon store is endangered: we estimate that 0.8 million hectares of old-growth African montane forest have been lost since 2000. We provide country-specific montane forest AGC stock estimates modelled from our plot network to help to guide forest conservation and reforestation interventions. Our findings highlight the need for conserving these biodiverse9,10 and carbon-rich ecosystems.


Assuntos
Atitude , Sequestro de Carbono , Carbono/análise , Floresta Úmida , Árvores/metabolismo , Clima Tropical , África , Biomassa , Mudança Climática , Conservação dos Recursos Naturais , Conjuntos de Dados como Assunto , Mapeamento Geográfico
3.
Nature ; 579(7797): 80-87, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-32132693

RESUMO

Structurally intact tropical forests sequestered about half of the global terrestrial carbon uptake over the 1990s and early 2000s, removing about 15 per cent of anthropogenic carbon dioxide emissions1-3. Climate-driven vegetation models typically predict that this tropical forest 'carbon sink' will continue for decades4,5. Here we assess trends in the carbon sink using 244 structurally intact African tropical forests spanning 11 countries, compare them with 321 published plots from Amazonia and investigate the underlying drivers of the trends. The carbon sink in live aboveground biomass in intact African tropical forests has been stable for the three decades to 2015, at 0.66 tonnes of carbon per hectare per year (95 per cent confidence interval 0.53-0.79), in contrast to the long-term decline in Amazonian forests6. Therefore the carbon sink responses of Earth's two largest expanses of tropical forest have diverged. The difference is largely driven by carbon losses from tree mortality, with no detectable multi-decadal trend in Africa and a long-term increase in Amazonia. Both continents show increasing tree growth, consistent with the expected net effect of rising atmospheric carbon dioxide and air temperature7-9. Despite the past stability of the African carbon sink, our most intensively monitored plots suggest a post-2010 increase in carbon losses, delayed compared to Amazonia, indicating asynchronous carbon sink saturation on the two continents. A statistical model including carbon dioxide, temperature, drought and forest dynamics accounts for the observed trends and indicates a long-term future decline in the African sink, whereas the Amazonian sink continues to weaken rapidly. Overall, the uptake of carbon into Earth's intact tropical forests peaked in the 1990s. Given that the global terrestrial carbon sink is increasing in size, independent observations indicating greater recent carbon uptake into the Northern Hemisphere landmass10 reinforce our conclusion that the intact tropical forest carbon sink has already peaked. This saturation and ongoing decline of the tropical forest carbon sink has consequences for policies intended to stabilize Earth's climate.


Assuntos
Dióxido de Carbono/metabolismo , Sequestro de Carbono , Florestas , Árvores/metabolismo , Clima Tropical , África , Atmosfera/química , Biomassa , Brasil , Secas , História do Século XX , História do Século XXI , Modelos Teóricos , Temperatura
4.
Glob Chang Biol ; 30(1): e17140, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38273497

RESUMO

Growing evidence suggests that liana competition with trees is threatening the global carbon sink by slowing the recovery of forests following disturbance. A recent theory based on local and regional evidence further proposes that the competitive success of lianas over trees is driven by interactions between forest disturbance and climate. We present the first global assessment of liana-tree relative performance in response to forest disturbance and climate drivers. Using an unprecedented dataset, we analysed 651 vegetation samples representing 26,538 lianas and 82,802 trees from 556 unique locations worldwide, derived from 83 publications. Results show that lianas perform better relative to trees (increasing liana-to-tree ratio) when forests are disturbed, under warmer temperatures and lower precipitation and towards the tropical lowlands. We also found that lianas can be a critical factor hindering forest recovery in disturbed forests experiencing liana-favourable climates, as chronosequence data show that high competitive success of lianas over trees can persist for decades following disturbances, especially when the annual mean temperature exceeds 27.8°C, precipitation is less than 1614 mm and climatic water deficit is more than 829 mm. These findings reveal that degraded tropical forests with environmental conditions favouring lianas are disproportionately more vulnerable to liana dominance and thus can potentially stall succession, with important implications for the global carbon sink, and hence should be the highest priority to consider for restoration management.


Des preuves de plus en plus nombreuses suggèrent que la competition entre lianes et les arbres menace le puits de carbone mondial en ralentissant la récupération des forêts après une perturbation. Une théorie récente, fondée sur des observations locales et régionales, propose en outre que le succès compétitif des lianes sur les arbres est dû aux interactions entre la perturbation forestière et le climat. Nous présentons la première évaluation mondiale de la performance relative des lianes par rapport aux arbres en réponse aux perturbations forestières et aux facteurs climatiques. En utilisant un ensemble de données sans précédent, nous avons analysé 651 échantillons de végétation représentant 26,538 lianes et 82,802 arbres, issus de 556 emplacements uniques dans le monde entier, tirés de 83 publications. Les résultats montrent que les lianes ont de meilleure performances par rapport aux arbres (augmentation du ratio liane-arbre) lorsque les forêts sont perturbées, sous des zones chaudes aves précipitations faibles, et vers les basses altitudes tropicales. Nous avons également constaté que les lianes peuvent être un facteur critique entravant la récupération des forêts dans les forêts perturbées connaissant des climats favorables aux lianes, car les données de chronoséquence montrent que le succès compétitif élevé des lianes sur les arbres peut persister pendant des décennies après les perturbations, surtout lorsque la température annuelle moyenne dépasse 27.8°C, que les précipitations sont inférieures à 1614 mm et que le déficit hydrique climatique est supérieur à 829 mm. Ces découvertes révèlent que les forêts tropicales dégradées avec des conditions environnementales favorables aux lianes sont disproportionnellement plus vulnérables à la dominance des lianes, et peuvent ainsi potentiellement entraver la succession, avec d'importantes implications pour le puits de carbone mondial et devraient donc être la plus haute priorité à considérer pour la gestion de la restauration.


Assuntos
Árvores , Clima Tropical , Árvores/fisiologia , Florestas , Sequestro de Carbono , Água
5.
Proc Natl Acad Sci U S A ; 118(21)2021 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-34001597

RESUMO

The responses of tropical forests to environmental change are critical uncertainties in predicting the future impacts of climate change. The positive phase of the 2015-2016 El Niño Southern Oscillation resulted in unprecedented heat and low precipitation in the tropics with substantial impacts on the global carbon cycle. The role of African tropical forests is uncertain as their responses to short-term drought and temperature anomalies have yet to be determined using on-the-ground measurements. African tropical forests may be particularly sensitive because they exist in relatively dry conditions compared with Amazonian or Asian forests, or they may be more resistant because of an abundance of drought-adapted species. Here, we report responses of structurally intact old-growth lowland tropical forests inventoried within the African Tropical Rainforest Observatory Network (AfriTRON). We use 100 long-term inventory plots from six countries each measured at least twice prior to and once following the 2015-2016 El Niño event. These plots experienced the highest temperatures and driest conditions on record. The record temperature did not significantly reduce carbon gains from tree growth or significantly increase carbon losses from tree mortality, but the record drought did significantly decrease net carbon uptake. Overall, the long-term biomass increase of these forests was reduced due to the El Niño event, but these plots remained a live biomass carbon sink (0.51 ± 0.40 Mg C ha-1 y-1) despite extreme environmental conditions. Our analyses, while limited to African tropical forests, suggest they may be more resistant to climatic extremes than Amazonian and Asian forests.


Assuntos
Mudança Climática , Floresta Úmida , Árvores/crescimento & desenvolvimento , Clima Tropical , Ciclo do Carbono , Secas , El Niño Oscilação Sul , Temperatura Alta , Humanos , Estações do Ano
6.
Urol Int ; 107(1): 35-45, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-34515257

RESUMO

INTRODUCTION: Guideline recommendations are meant to help minimize morbidity and to improve the care of nonmuscle invasive bladder cancer (NMIBC) patients but studies have suggested an underuse of guideline-recommended care. The aim of this study was to evaluate the level of adherence of German and Austrian urologists to German guideline recommendations. METHODS: A survey of 27 items evaluating diagnostic and therapeutic recommendations (15 cases of strong consensus and 6 cases of consensus) for NMIBC was administered among 14 urologic training courses. Survey construction and realization followed the checklist for reporting results of internet e-surveys and was approved by an internal review board. RESULTS: Between January 2018 and June 2019, a total of 307 urologists responded to the questionnaire, with a mean response rate of 71%. The data showed a weak role of urine cytology (54%) for initial diagnostics although it is strongly recommended by the guideline. The most frequently used supporting diagnostic tool during transurethral resection of the bladder was hexaminolevulinate (95%). Contrary to the guideline recommendation, 38% of the participants performed a second resection in the case of pTa low-grade NMIBC. Correct monitoring of Bacille Calmette-Guérin (BCG) response with cystoscopy and cytology was performed by only 34% of the urologists. CONCLUSIONS: We found a discrepancy between certain guideline recommendations and daily routine practice concerning the use of urine cytology for initial diagnostics, instillation therapy with a low monitoring rate of BCG response, and follow-up care with unnecessary second resection after pTa low-grade NMIBC in particular. Our survey showed a moderate overall adherence rate of 73%. These results demonstrate the need for sharpening awareness of German guideline recommendations by promoting more intense education of urologists to optimize NMIBC care thus decreasing morbidity and mortality rates.


Assuntos
Neoplasias da Bexiga Urinária , Urologia , Humanos , Vacina BCG/uso terapêutico , Neoplasias da Bexiga Urinária/cirurgia , Bexiga Urinária , Inquéritos e Questionários , Administração Intravesical , Invasividade Neoplásica , Recidiva Local de Neoplasia/tratamento farmacológico
7.
BJU Int ; 130(6): 754-763, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34928524

RESUMO

OBJECTIVES: To evaluate the clinical utility of the urinary bladder cancer antigen test UBC® Rapid for the diagnosis of bladder cancer (BC) and to develop and validate nomograms to identify patients at high risk of primary BC. PATIENTS AND METHODS: Data from 1787 patients from 13 participating centres, who were tested between 2012 and 2020, including 763 patients with BC, were analysed. Urine samples were analysed with the UBC® Rapid test. The nomograms were developed using data from 320 patients and externally validated using data from 274 patients. The diagnostic accuracy of the UBC® Rapid test was evaluated using receiver-operating characteristic curve analysis. Brier scores and calibration curves were chosen for the validation. Biopsy-proven BC was predicted using multivariate logistic regression. RESULTS: The sensitivity, specificity, and area under the curve for the UBC® Rapid test were 46.4%, 75.5% and 0.61 (95% confidence interval [CI] 0.58-0.64) for low-grade (LG) BC, and 70.5%, 75.5% and 0.73 (95% CI 0.70-0.76) for high-grade (HG) BC, respectively. Age, UBC® Rapid test results, smoking status and haematuria were identified as independent predictors of primary BC. After external validation, nomograms based on these predictors resulted in areas under the curve of 0.79 (95% CI 0.72-0.87) and 0.95 (95% CI: 0.92-0.98) for predicting LG-BC and HG-BC, respectively, showing excellent calibration associated with a higher net benefit than the UBC® Rapid test alone for low and medium risk levels in decision curve analysis. The R Shiny app allows the results to be explored interactively and can be accessed at www.blucab-index.net. CONCLUSION: The UBC® Rapid test alone has limited clinical utility for predicting the presence of BC. However, its combined use with BC risk factors including age, smoking status and haematuria provides a fast, highly accurate and non-invasive tool for screening patients for primary LG-BC and especially primary HG-BC.


Assuntos
Neoplasias da Bexiga Urinária , Humanos , Neoplasias da Bexiga Urinária/diagnóstico , Neoplasias da Bexiga Urinária/urina , Nomogramas , Hematúria , Curva ROC , Fatores de Risco
8.
BMC Cancer ; 20(1): 140, 2020 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-32085750

RESUMO

BACKGROUND: Whether or not double J (DJ) stenting during transurethral resection of a bladder tumour (TURBT) harms patients with regard to possible metachronous upper urinary tract urothelial cancer (UUTUC) development remains controversial. This study evaluated the impact of DJ compared to nephrostomy placement during TURBT for bladder cancer (BCa) on the incidence of metachronous UUTUCs. METHODS: We retrospectively analysed 637 patients who underwent TURBT in our department between 2008 and 2016. BCa, UUTUC and urinary drainage data (retrograde/anterograde DJ and percutaneous nephrostomy) were assessed, along with the prevalence of hydronephrosis, and mortality. Chi-square and Fisher's exact test was performed for univariate analyses. Survival analysis was performed by the Kaplan-Meier method and log-rank tests. RESULTS: UUTUC was noted in 28 out of 637 patients (4.4%), whereas only eight (1.3%) developed it metachronously to BCa. Out of these, four patients received DJ stents, while four patients received no urinary drainage of the upper urinary tract. Placement of urinary drainage significantly correlated with UUTUC (50.0% vs. 17.9%; p = 0.041). DJ stenting significantly correlated with UUTUC (50.0% vs. 11%; p <  0.01), while no patient with a nephrostomy tube developed UUTUC. UUTUC-free survival rates were significantly lower for patients with DJ stents than for all other patients (p = 0.001). Patients with or without DJ stents had similar overall survival (OS) rates (p = 0.73), whereas patients with nephrostomy tubes had significantly lower OS rates than all other patients (p <  0.001). CONCLUSIONS: Patients with DJ stenting during TURBT for BCa might have an increased risk of developing metachronous UUTUC. This study indicated advantages in placing nephrostomy tubes rather than DJ stents; however, confirmation requires investigation of a larger cohort. Even so, the increased mortality rate in the nephrostomy group reflected hydronephrosis as an unfavourable prognostic factor.


Assuntos
Segunda Neoplasia Primária/epidemiologia , Nefrotomia/efeitos adversos , Stents/efeitos adversos , Neoplasias da Bexiga Urinária/cirurgia , Neoplasias Urológicas/epidemiologia , Urotélio/patologia , Idoso , Drenagem , Feminino , Alemanha/epidemiologia , Humanos , Incidência , Masculino , Estadiamento de Neoplasias , Segunda Neoplasia Primária/patologia , Estudos Retrospectivos , Taxa de Sobrevida , Neoplasias da Bexiga Urinária/patologia , Neoplasias Urológicas/patologia
9.
Ann Bot ; 125(2): 315-324, 2020 02 03.
Artigo em Inglês | MEDLINE | ID: mdl-31304956

RESUMO

BACKGROUND AND AIMS: The vegetation that grows on coastal wetlands is important for ecosystem functioning, a role mediated by plant traits. These traits can be affected by environmental stressors and by the competitive environment the plant experiences. The relative importance of these influences on different traits is poorly understood and, despite theoretical expectations for how factors may interact, empirical data are conflicting. Our aims are to determine the effect of flooding, species composition and their interaction on plant functional traits, and assess the role of biodiversity and species composition in driving community-level responses to flooding. METHODS: We conducted a factorial glasshouse experiment assessing the effects of species composition (all combinations of three saltmarsh species, Aster tripolium, Plantago maritima and Triglochin maritima) and flooding (immersion of roots) on a suite of functional traits. We also related biomass in mixed species pots to that expected from monocultures to assess how species interactions affect community-level biomass. KEY RESULTS: Species composition frequently interacted with flooding to influence functional traits and community-level properties. However, there was also considerable intraspecific variability in traits within each treatment. Generally, effects of flooding were more pronounced for below-ground than above-ground biomass, while composition affected above-ground biomass more than below-ground biomass. We found both negative and positive interactions between species (indicated by differences in above- and below-ground biomass from expectations under monoculture), meaning that composition was an important determinate of community function. CONCLUSIONS: While the effect of flooding alone on traits was relatively weak, it interacted with species composition to modify the response of both individual plants and communities. Our results suggest that responses to increased flooding will be complex and depend on neighbourhood species interactions. Furthermore, intraspecific trait variability is a potential resource that may dampen the effects of changes in flooding regime.


Assuntos
Ecossistema , Plantas , Biodiversidade , Biomassa , Inundações
10.
Urol Int ; 104(5-6): 452-458, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32097920

RESUMO

INTRODUCTION: The aim of this study was to analyze the influence of residents' participation in flexible ureteroscopy (fURS) on intra- and postoperative outcomes. MATERIALS AND METHODS: Intra- and postoperative parameters were compared in a retrospective monocentric setting between 3 groups: "resident group" (47 cases) for surgeries performed by experienced residents alone, "consultant group" (245 cases) for surgeries performed by consultants alone, "resident plus consultant group" (124 cases) for training surgeries between September 2013 and June 2017. RESULTS: Patients operated by residents alone had a significantly smaller median kidney stone diameter (5.0 vs. 7.0 mm for "consultant group" and 6.0 mm for "resident plus consultant group," p = 0.011), shorter operating time (median 47.0 vs. 63.0 and 77.0 min, p < 0.001) and fluoroscopy time (median 39.0 vs. 69.5 and 89.0 s, p < 0.001), as well as shorter postoperative hospital stay (p = 0.013). The laser application rate was the smallest in the "resident group" (10.64 vs. 31.43 and 29.84%, p = 0.009). Univariate analysis revealed no relevant differences regarding flexible ureteroscope defect rate, postoperative stone-free rate, or ≥2 Clavien-Dindo classification complications between the groups (p > 0.05). CONCLUSION: A proper case selection of less complicated cases, especially without laser application, could balance the experience deficit of the residents. fURS can be incorporated as a part of residents' training without an impact on fURS device defect rate or clinical outcomes.


Assuntos
Competência Clínica , Internato e Residência , Cálculos Renais/cirurgia , Ureteroscopia , Urologia/educação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Resultado do Tratamento , Ureteroscópios , Ureteroscopia/instrumentação , Adulto Jovem
11.
Glob Chang Biol ; 25(11): 3609-3624, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31310673

RESUMO

As countries advance in greenhouse gas (GHG) accounting for climate change mitigation, consistent estimates of aboveground net biomass change (∆AGB) are needed. Countries with limited forest monitoring capabilities in the tropics and subtropics rely on IPCC 2006 default ∆AGB rates, which are values per ecological zone, per continent. Similarly, research into forest biomass change at a large scale also makes use of these rates. IPCC 2006 default rates come from a handful of studies, provide no uncertainty indications and do not distinguish between older secondary forests and old-growth forests. As part of the 2019 Refinement to the 2006 IPCC Guidelines for National Greenhouse Gas Inventories, we incorporate ∆AGB data available from 2006 onwards, comprising 176 chronosequences in secondary forests and 536 permanent plots in old-growth and managed/logged forests located in 42 countries in Africa, North and South America and Asia. We generated ∆AGB rate estimates for younger secondary forests (≤20 years), older secondary forests (>20 years and up to 100 years) and old-growth forests, and accounted for uncertainties in our estimates. In tropical rainforests, for which data availability was the highest, our ∆AGB rate estimates ranged from 3.4 (Asia) to 7.6 (Africa) Mg ha-1  year-1 in younger secondary forests, from 2.3 (North and South America) to 3.5 (Africa) Mg ha-1  year-1 in older secondary forests, and 0.7 (Asia) to 1.3 (Africa) Mg ha-1  year-1 in old-growth forests. We provide a rigorous and traceable refinement of the IPCC 2006 default rates in tropical and subtropical ecological zones, and identify which areas require more research on ∆AGB. In this respect, this study should be considered as an important step towards quantifying the role of tropical and subtropical forests as carbon sinks with higher accuracy; our new rates can be used for large-scale GHG accounting by governmental bodies, nongovernmental organizations and in scientific research.


Assuntos
Árvores , Clima Tropical , África , Ásia , Biomassa , Carbono , Florestas , América do Sul
12.
Glob Chang Biol ; 25(1): 39-56, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30406962

RESUMO

Most of the planet's diversity is concentrated in the tropics, which includes many regions undergoing rapid climate change. Yet, while climate-induced biodiversity changes are widely documented elsewhere, few studies have addressed this issue for lowland tropical ecosystems. Here we investigate whether the floristic and functional composition of intact lowland Amazonian forests have been changing by evaluating records from 106 long-term inventory plots spanning 30 years. We analyse three traits that have been hypothesized to respond to different environmental drivers (increase in moisture stress and atmospheric CO2 concentrations): maximum tree size, biogeographic water-deficit affiliation and wood density. Tree communities have become increasingly dominated by large-statured taxa, but to date there has been no detectable change in mean wood density or water deficit affiliation at the community level, despite most forest plots having experienced an intensification of the dry season. However, among newly recruited trees, dry-affiliated genera have become more abundant, while the mortality of wet-affiliated genera has increased in those plots where the dry season has intensified most. Thus, a slow shift to a more dry-affiliated Amazonia is underway, with changes in compositional dynamics (recruits and mortality) consistent with climate-change drivers, but yet to significantly impact whole-community composition. The Amazon observational record suggests that the increase in atmospheric CO2 is driving a shift within tree communities to large-statured species and that climate changes to date will impact forest composition, but long generation times of tropical trees mean that biodiversity change is lagging behind climate change.


Assuntos
Biodiversidade , Mudança Climática , Florestas , Brasil , Dióxido de Carbono , Ecossistema , Estações do Ano , Árvores/classificação , Árvores/fisiologia , Clima Tropical , Água
13.
Plant Cell Environ ; 41(7): 1618-1631, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-29603771

RESUMO

Given anticipated climate changes, it is crucial to understand controls on leaf temperatures including variation between species in diverse ecosystems. In the first study of leaf energy balance in tropical montane forests, we observed current leaf temperature patterns on 3 tree species in the Atlantic forest, Brazil, over a 10-day period and assessed whether and why patterns may vary among species. We found large leaf-to-air temperature differences (maximum 18.3 °C) and high leaf temperatures (over 35 °C) despite much lower air temperatures (maximum 22 °C). Leaf-to-air temperature differences were influenced strongly by radiation, whereas leaf temperatures were also influenced by air temperature. Leaf energy balance modelling informed by our measurements showed that observed differences in leaf temperature between 2 species were due to variation in leaf width and stomatal conductance. The results suggest a trade-off between water use and leaf thermoregulation; Miconia cabussu has more conservative water use compared with Alchornea triplinervia due to lower transpiration under high vapour pressure deficit, with the consequence of higher leaf temperatures under thermal stress conditions. We highlight the importance of leaf functional traits for leaf thermoregulation and also note that the high radiation levels that occur in montane forests may exacerbate the threat from increasing air temperatures.


Assuntos
Folhas de Planta/fisiologia , Árvores/fisiologia , Regulação da Temperatura Corporal/fisiologia , Brasil , Metabolismo Energético , Euphorbiaceae/metabolismo , Euphorbiaceae/fisiologia , Melastomataceae/metabolismo , Melastomataceae/fisiologia , Nyctaginaceae/metabolismo , Nyctaginaceae/fisiologia , Folhas de Planta/metabolismo , Temperatura , Árvores/metabolismo , Água/metabolismo
14.
Ann Oncol ; 27(6): 998-1005, 2016 06.
Artigo em Inglês | MEDLINE | ID: mdl-26951625

RESUMO

Many classes of anticancer therapy, including chemotherapeutic agents, hormonal and molecular targeted treatments, can produce ocular toxicity. Novel agents that target different cellular pathways have been related to a wide spectrum of ophthalmologic toxicities that can range from mild to severe, and include conjunctivitis, blurred vision, keratitis and optic neuritis, among others. Special attention has been drawn to the inhibitors of the MEK signaling pathway, due to their sine qua non ocular toxicity, defined as MEK retinopathy and described as symmetrical bilateral disease that develops in a time-dependent and dose-dependent manner. In this review, we discuss ophthalmologic toxicities associated with molecular targeted therapies, with particular focus on MEK retinopathy, including its nomenclature, incidence, symptoms and management.


Assuntos
Antineoplásicos/efeitos adversos , Terapia de Alvo Molecular/efeitos adversos , Neoplasias/tratamento farmacológico , Doenças Retinianas/fisiopatologia , Antineoplásicos/uso terapêutico , Humanos , MAP Quinase Quinase Quinases/antagonistas & inibidores , Neoplasias/complicações , Neoplasias/epidemiologia , Neoplasias/patologia , Inibidores de Proteínas Quinases/efeitos adversos , Inibidores de Proteínas Quinases/uso terapêutico , Doenças Retinianas/induzido quimicamente , Doenças Retinianas/classificação , Doenças Retinianas/epidemiologia , Transdução de Sinais/efeitos dos fármacos
15.
Glob Chang Biol ; 22(4): 1655-65, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26833671

RESUMO

Forecasting impacts of future climate change is an important challenge to biologists, both for understanding the consequences of different emissions trajectories and for developing adaptation measures that will minimize biodiversity loss. Existing variation provides a window into the effects of climate on species and ecosystems, but in many places does not encompass the levels or timeframes of forcing expected under directional climatic change. Experiments help us to fill in these uncertainties, simulating directional shifts to examine outcomes of new levels and sustained changes in conditions. Here, we explore the translation between short-term responses to climate variability and longer-term trajectories that emerge under directional climatic change. In a decade-long experiment, we compare effects of short-term and long-term forcings across three trophic levels in grassland plots subjected to natural and experimental variation in precipitation. For some biological responses (plant productivity), responses to long-term extension of the rainy season were consistent with short-term responses, while for others (plant species richness, abundance of invertebrate herbivores and predators), there was pronounced divergence of long-term trajectories from short-term responses. These differences between biological responses mean that sustained directional changes in climate can restructure ecological relationships characterizing a system. Importantly, a positive relationship between plant diversity and productivity turned negative under one scenario of climate change, with a similar change in the relationship between plant productivity and consumer biomass. Inferences from experiments such as this form an important part of wider efforts to understand the complexities of climate change responses.


Assuntos
Biodiversidade , Mudança Climática , Pradaria , Desenvolvimento Vegetal , Animais , Biomassa , California , Herbivoria , Invertebrados , Densidade Demográfica , Chuva , Estações do Ano
16.
Phys Rev Lett ; 114(23): 231302, 2015 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-26196790

RESUMO

New data are reported from the operation of a 2 liter C3F8 bubble chamber in the SNOLAB underground laboratory, with a total exposure of 211.5 kg days at four different energy thresholds below 10 keV. These data show that C3F8 provides excellent electron-recoil and alpha rejection capabilities at very low thresholds. The chamber exhibits an electron-recoil sensitivity of <3.5×10(-10) and an alpha rejection factor of >98.2%. These data also include the first observation of a dependence of acoustic signal on alpha energy. Twelve single nuclear recoil event candidates were observed during the run. The candidate events exhibit timing characteristics that are not consistent with the hypothesis of a uniform time distribution, and no evidence for a dark matter signal is claimed. These data provide the most sensitive direct detection constraints on WIMP-proton spin-dependent scattering to date, with significant sensitivity at low WIMP masses for spin-independent WIMP-nucleon scattering.


Assuntos
Fluorocarbonos/química , Modelos Teóricos , Acústica/instrumentação , Algoritmos , Nêutrons
17.
Biol Lett ; 11(1): 20140930, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25589487

RESUMO

A long-standing aim of ecologists is to understand the processes involved in regulating populations. One such mechanism is the buffer effect, where lower quality habitats are increasingly used as a species reaches higher population densities, with a resultant average reduction in fecundity and survival limiting population growth. Although the buffer effect has been demonstrated in populations of a number of species, a test of its importance in influencing population growth rates of multiple species across large spatial scales is lacking. Here, we use habitat-specific population trends for 85 bird species from long-term national monitoring data (the UK Breeding Bird Survey) to examine its generality. We find that both patterns of population change and changes in habitat preference are consistent with the predictions of the buffer effect, providing support for its widespread operation.


Assuntos
Aves/fisiologia , Ecossistema , Dinâmica Populacional , Distribuição Animal , Animais , Fertilidade/fisiologia , Densidade Demográfica , Reino Unido
18.
Urol Oncol ; 41(12): 484.e17-484.e26, 2023 12.
Artigo em Inglês | MEDLINE | ID: mdl-37407421

RESUMO

INTRODUCTION AND OBJECTIVE: BTA stat®, NMP22® BladderChek®, UBC® Rapid Test, and CancerCheck® UBC® rapid VISUAL are urinary-based rapid tests. This multicenter study is the first study comparing all available rapid tests on a large cohort of bladder cancer patients and healthy controls in one setting. METHODS: In total 732 urine samples (second morning urine) in a real-world assessment have been analyzed. We evaluated clinical samples from 464 patients with histologically confirmed urothelial tumors of the urinary bladder (17 solitary CIS, 189 low-grade, 187 high-grade nonmuscle invasive, 71 high-grade muscle invasive), 77 patients with No Evidence of Disease (NED), and from 191 healthy controls. Urine samples were analyzed by the BTA stat®, NMP22® BladderChek®, UBC® Rapid Test point-of-care (POC) system using the concile Omega 100 POC reader, and CancerCheck® UBC® rapid VISUAL. Sensitivities and specificities were calculated by contingency analyses. RESULTS: All investigated urinary markers detected more pathological concentrations in urine of bladder cancer patients compared to tumor-free patients. The calculated diagnostic sensitivities for BTA stat®, NMP22® BladderChek®, UBC® Rapid Test, CancerCheck® UBC® rapid VISUAL, and cytology were 62.4%, 13.4%, 58.2%, 28.6%, 36.2% for low-grade, 83.4%, 49.5%, 84.5%, 63.1%, 71.2% for high-grade nonmuscle invasive, and 95.8%, 35.2%, 76.1%, 50.7%, 67.7% for high-grade muscle-invasive bladder cancer. The specificity was 67.9%, 95.5%, 79.4%, 94.4%, and 83.7%, respectively. The area under the curve (AUC) after receiver operating characteristics (ROC) analysis for high-grade non-muscle-invasive tumors was 0.757, 0.725, 0.819, 0.787, and 0.774, respectively. CONCLUSIONS: The analysis of more than 700 urine samples offers an objective view on urine-based rapid diagnostics. Elevated pathological concentrations of markers in urine of bladder cancer patients were detected in all investigated tests. The highest sensitivities for high-grade non-muscle-invasive tumors were calculated for BTA stat® and UBC® Rapid Test, whereas NMP22® BladderChek®, and cytology showed the highest specificities. BTA stat® and UBC® Rapid Test have the potential to be used as a clinical valuable urinary protein biomarker for the detection of high-grade non-muscle-invasive bladder cancer patients and could be included in the management of these tumors.


Assuntos
Biomarcadores Tumorais , Neoplasias da Bexiga Urinária , Humanos , Biomarcadores Tumorais/urina , Neoplasias da Bexiga Urinária/patologia , Proteínas Nucleares/urina , Sensibilidade e Especificidade
19.
PLoS One ; 17(11): e0259033, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36449465

RESUMO

Increasing attention is being paid to the carbon sequestration and storage services provided by coastal blue carbon ecosystems such as saltmarshes. Sites restored by managed realignment, where existing sea walls are breached to reinstate tidal inundation to the land behind, have considerable potential to accumulate carbon through deposition of sediment brought in by the tide and burial of vegetation in the site. While this potential has been recognised, it is not yet a common motivating factor for saltmarsh restoration, partly due to uncertainties about the rate of carbon accumulation and how this balances against the greenhouse gases emitted during site construction. We use a combination of field measurements over four years and remote sensing to quantify carbon accumulation at a large managed realignment site, Steart Marshes, UK. Sediment accumulated rapidly at Steart Marshes (mean of 75 mm yr-1) and had a high carbon content (4.4% total carbon, 2.2% total organic carbon), resulting in carbon accumulation of 36.6 t ha-1 yr-1 total carbon (19.4 t ha-1 yr-1 total organic carbon). This rate of carbon accumulation is an order of magnitude higher than reported in many other restored saltmarshes, and is somewhat higher than values previously reported from another hypertidal system (Bay of Fundy, Canada). The estimated carbon emissions associated with the construction of the site were ~2-4% of the observed carbon accumulation during the study period, supporting the view that managed realignment projects in such settings may have significant carbon accumulation benefits. However, uncertainties such as the origin of carbon (allochthonous or autochthonous) and changes in gas fluxes need to be resolved to move towards a full carbon budget for saltmarsh restoration.


Assuntos
Carbono , Gases de Efeito Estufa , Ecossistema , Sequestro de Carbono , Áreas Alagadas
20.
Adv Ther ; 38(1): 258-267, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33094476

RESUMO

INTRODUCTION: For risk stratification of non-muscle invasive bladder cancer (NMIBC), the depth of stromal invasion can be further classified, where the lamina muscularis mucosae (MM) serves as a reference structure. While the overall identifiability of MM in standard transurethral specimens is low, en bloc resection may help in identification and overall orientation. The aims of this study were to report the detection rate of MM in en bloc resected bladder tumors (ERBT) and to provide real-world information on tissue stability and preservation of en bloc architecture during recovery and processing for histopathologic evaluation. METHODS: Thirty-four ERBT specimens were histologically re-evaluated with regard to MM detectability and structure as well as the presence of en bloc architecture and further histologic features. Associations with tumor size and energy source and within histologic parameters were assessed by standard Pearson's chi-squared analyses and Cramér's V effect size testing (V). RESULTS: The first parameter assessed was MM detection rate. In 19 out of 34 samples (56%) MM was detectable: scattered in 9 cases (26%), interrupted in 8 cases (24%) and continuous in 2 cases (6%). The second parameter assessed was preservation of en bloc architecture. In 11 out of 34 samples (32%), en bloc architecture could not be confirmed, and these samples served as a reference group for the detection of MM. Preservation of en bloc architecture was associated with an increased MM detection rate (MM in en bloc preserved 16/23, 70% vs. non-preserved 3/11, 27%; p = 0.020; V = 0.398) and with tumor size (p = 0.005; V = 0.595). Medium-sized tumors (1.1-2 cm) were best preserved. The choice of energy source did not show relevant association with en bloc architecture (p = n.s.). CONCLUSIONS: In line with recent publications, ERBT increases the MM detection rate considerably. However, a third of the ERBT specimens lost en bloc architecture during sample recovery and processing. Tumor size is a relevant factor, with optimal architecture preservation between 1 and 2 cm. Optimizing resection techniques, recovery, transport, and diagnostic processing of ERBT samples is warranted to verify the diagnostic value of MM-based substaging.


Assuntos
Neoplasias da Bexiga Urinária , Cistectomia , Humanos , Mucosa , Estudos Retrospectivos , Neoplasias da Bexiga Urinária/cirurgia
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA