Tree allometric relationships are widely employed for estimating forest biomass
and production and are basic building blocks of dynamic vegetation models.
In tropical forests, allometric ...relationships are often modeled by fitting
scale-invariant power functions to pooled data from multiple species, an
approach that fails to capture changes in scaling during ontogeny and
physical limits to maximum tree size and that ignores interspecific
differences in allometry. Here, we analyzed allometric relationships of tree
height (9884 individuals) and crown area (2425) with trunk diameter for 162
species from the Barro Colorado Nature Monument, Panama. We fit
nonlinear, hierarchical models informed by species traits –
wood density, mean sapling growth, or sapling mortality – and assessed the
performance of three alternative functional forms: the scale-invariant power
function and the saturating Weibull and generalized Michaelis–Menten (gMM)
functions. The relationship of tree height with trunk diameter was best fit
by a saturating gMM model in which variation in allometric parameters was
related to interspecific differences in sapling growth rates, a measure of
regeneration light demand. Light-demanding species attained taller heights at
comparatively smaller diameters as juveniles and had shorter asymptotic
heights at larger diameters as adults. The relationship of crown area with
trunk diameter was best fit by a power function model incorporating a weak
positive relationship between crown area and species-specific wood density.
The use of saturating functional forms and the incorporation of functional
traits in tree allometric models is a promising approach for improving estimates
of forest biomass and productivity. Our results provide an improved basis for
parameterizing tropical plant functional types in vegetation models.
Tropical forests are a key determinant of the functioning of the Earth system, but remain a major source of uncertainty in carbon cycle models and climate change projections. In this study, we ...present an updated land model (LM3PPA‐TV) to improve the representation of tropical forest structure and dynamics in Earth system models (ESMs). The development and parameterization of LM3PPA‐TV drew on extensive datasets on tropical tree traits and long‐term field censuses from Barro Colorado Island (BCI), Panama. The model defines a new plant functional type (PFT) based on the characteristics of shade‐tolerant, tropical tree species, implements a new growth allocation scheme based on realistic tree allometries, incorporates hydraulic constraints on biomass accumulation, and features a new compartment for tree branches and branch fall dynamics. Simulation experiments reproduced observed diurnal and seasonal patterns in stand‐level carbon and water fluxes, as well as mean canopy and understory tree growth rates, tree size distributions, and stand‐level biomass on BCI. Simulations at multiple sites captured considerable variation in biomass and size structure across the tropical forest biome, including observed responses to precipitation and temperature. Model experiments suggested a major role of water limitation in controlling geographic variation forest biomass and structure. However, the failure to simulate tropical forests under extreme conditions and the systematic underestimation of forest biomass in Paleotropical locations highlighted the need to incorporate variation in hydraulic traits and multiple PFTs that capture the distinct floristic composition across tropical domains. The continued pressure on tropical forests from global change demands models which are able to simulate alternative successional pathways and their pace to recovery. LM3PPA‐TV provides a tool to investigate geographic variation in tropical forests and a benchmark to continue improving the representation of tropical forests dynamics and their carbon storage potential in ESMs.
Tropical forests are a key determinant of the functioning of the Earth system, but remain a major source of uncertainty in carbon cycle models and climate change projections. We present an updated land model (LM3PPA‐TV) to improve the representation of tropical forest structure and dynamics in Earth system models.
Tropical forests contribute a major sink for anthropogenic carbon emissions essential to slowing down the buildup of atmospheric CO
and buffering climate change impacts. However, the response of ...tropical forests to more frequent weather extremes and long-recovery disturbances like fires remains uncertain. Analyses of field data and ecological theory raise concerns about the possibility of the Amazon crossing a tipping point leading to catastrophic tropical forest loss. In contrast, climate models consistently project an enhanced tropical sink. Here, we show a heterogeneous response of Amazonian carbon stocks in GFDL-ESM4.1, an Earth System Model (ESM) featuring dynamic disturbances and height-structured tree-grass competition. Enhanced productivity due to CO
fertilization promotes increases in forest biomass that, under low emission scenarios, last until the end of the century. Under high emissions, positive trends reverse after 2060, when simulated fires prompt forest loss that results in a 40% decline in tropical forest biomass by 2100. Projected fires occur under dry conditions associated with El Niño Southern Oscillation and the Atlantic Multidecadal Oscillation, a response observed under current climate conditions, but exacerbated by an overall decline in precipitation. Following the initial disturbance, grassland dominance promotes recurrent fires and tree competitive exclusion, which prevents forest recovery. EC-Earth3-Veg, an ESM with a dynamic vegetation model of similar complexity, projected comparable wildfire forest loss under high emissions but faster postfire recovery rates. Our results reveal the importance of complex nonlinear responses to assessing climate change impacts and the urgent need to research postfire recovery and its representation in ESMs.
Aim
To examine the effects of expert HIV patients acting as teachers to Spanish nursing students both on their HIV‐related knowledge, attitudes and practices and on their approach to the care model ...as well as to explore their learning experience.
Design
Non‐randomized, single‐arm study with quantitative before and after measurements and qualitative data.
Methods
The intervention consisted of five 90‐min workshops led by two women living with HIV. Thirty‐four nursing students participated, and quantitative and qualitative data were gathered from February to June 2018. We used the Patient‐Practitioner Orientation Scale (PPOS) and the KAP questionnaire on HIV/AIDS to collect quantitative data.
Results
Statistically significant differences were found in the global score for care orientation and its two dimensions, caring and sharing. About the changes resulting from the workshops, the quantitative results—more patient‐centred care perception and better attitudes towards people living with HIV—match the qualitative findings in all the aspects studied, except in sharing.
Conclusion
Incorporating expert patients as teachers in the nursing bachelor's degree resulted in more patient‐centred care and improved knowledge, attitudes and practices. The workshops conducted by qualified expert patients showed transformative learning power, as the participants improved professional and personal aspects.
Understanding what factors drive fluctuations in the abundance of endangered species is a difficult ecological problem but a major requirement to attain effective management and conservation success. ...The ecological traits of large mammals make this task even more complicated, calling for integrative approaches. We develop a framework combining individual-based modelling and statistical inference to assess alternative hypotheses on brown bear dynamics in the Cantabrian range (Iberian Peninsula). Models including the effect of environmental factors on mortality rates were able to reproduce three decades of variation in the number of females with cubs of the year (Fcoy), including the decline that put the population close to extinction in the mid-nineties, and the following increase in brown bear numbers. This external effect prevailed over density-dependent mechanisms (sexually selected infanticide and female reproductive suppression), with a major impact of climate driven changes in resource availability and a secondary role of changes in human pressure. Predicted changes in population structure revealed a nonlinear relationship between total abundance and the number of Fcoy, highlighting the risk of simple projections based on indirect abundance indices. This study demonstrates the advantages of integrative, mechanistic approaches and provides a widely applicable framework to improve our understanding of wildlife dynamics.
Representing biological nitrogen fixation (BNF) is an important challenge for coupled carbon (C) and nitrogen (N) land models. Initial representations of BNF in land models applied simplified ...phenomenological relationships. More recent representations of BNF are mechanistic and include the dynamic response of symbiotic BNF to N limitation of plant growth. However, they generally do not include the competitive dynamics between N-fixing and non-fixing plants, which is a key ecological mechanism that determines ecosystem-scale symbiotic BNF. Furthermore, asymbiotic BNF is generally not included in land models. Here, we present LM4.1-BNF, a novel representation of BNF (asymbiotic and symbiotic) and an updated representation of N cycling in the Geophysical Fluid Dynamics Laboratory Land Model 4.1 (LM4.1). LM4.1-BNF incorporates a mechanistic representation of asymbiotic BNF by soil microbes, a representation of the competitive dynamics between N-fixing and non-fixing plants, and distinct asymbiotic and symbiotic BNF temperature responses derived from corresponding observations. LM4.1-BNF makes reasonable estimations of major carbon (C) and N pools and fluxes and their temporal dynamics, in comparison to the previous version of LM4.1 with N cycling (LM3-SNAP) and to previous representations of BNF in land models generally (phenomenological representations and those without competitive dynamics between N-fixing and non-fixing plants and/or asymbiotic BNF) at a temperate forest site. LM4.1-BNF effectively reproduces asymbiotic BNF rate (13 kgNha-1yr-1) in comparison to observations (11 kgNha-1yr-1). LM4.1-BNF effectively reproduces the temporal dynamics of symbiotic BNF rate: LM4.1-BNF simulates a symbiotic BNF pulse in early succession that reaches 73 kgNha-1yr-1 at 15 years and then declines to ∼0 kgNha-1yr-1 at 300 years, similarly to observed symbiotic BNF, which reaches 75 kgNha-1yr-1 at 17 years and then declines to ∼0 kgNha-1yr-1 in late successional forests. As such, LM4.1-BNF can be applied to project the dynamic response of vegetation to N limitation of plant growth and the degree to which this will constrain the terrestrial C sink under elevated atmospheric CO2 concentration and other global change factors.
Aims and Objectives
To identify how pregnant women perceive pertussis and influenza and the factors that influence their decision to be vaccinated.
Background
Suffering from influenza during ...pregnancy increases complications in the pregnant woman, foetus and newborn. Pertussis in children under six months of age causes severe complications. Maternal vaccination against influenza and pertussis is effective and safe. However, vaccination rates are insufficient.
Design
We conducted a qualitative descriptive study, using semi‐structured interviews. This research adheres to the COREQ guidelines and checklist.
Methods
We carried out 18 semi‐structured face‐to‐face interviews with pregnant women, using intentional sampling and thematic analysis.
Results
We identified an overarching theme, ‘factors that influenced participants’ decision to be vaccinated or not’, which was composed of four subthemes that were in turn made up of 12 categories. The factors that influenced participants’ decision to be vaccinated against influenza and pertussis were related to their knowledge of and their perception of risk for these diseases. Participants perceived the risk of pertussis to be greater, and they focused their concern on the newborn. The recommendations and convictions of nurse‐midwives were the most important factors encouraging vaccination. Participants trusted their nurse‐midwives and most reported that they would have been vaccinated if their midwife had recommended it. Other factors were linked to lack of information, fear and concerns about economic interests.
Conclusions
The convictions and actions of the nurse‐midwife in recommending vaccination to pregnant women are decisive. Strategies to improve vaccination rates should be directed to helping health professionals understand how their practice affects the final decision of pregnant women.
Relevance to clinical practice
Understanding the factors that limit vaccination rates among pregnant women provides valuable information to nurse‐midwives that can help to improve vaccination strategies and practices. Increased maternal vaccination rates would reduce morbidity and mortality among pregnant women and newborns.
Abstract
Background
Respondent-driven sampling (RDS) is a peer chain-recruitment method for populations without a sampling frame or that are hard-to-reach. Although RDS is usually done face-to-face, ...the online version (WebRDS) has drawn a lot of attention as it has many potential benefits, despite this, to date there is no clear framework for its implementation. This article aims to provide guidance for researchers who want to recruit through a WebRDS.
Methods
Description of the development phase: guidance is provided addressing aspects related to the formative research, the design of the questionnaire, the implementation of the coupon system using a free software and the diffusion plan, using as an example a web-based cross-sectional study conducted in Spain between April and June 2022 describing the working conditions and health status of homecare workers for dependent people.
Results
The application of the survey: we discuss about the monitoring strategies throughout the recruitment process and potential problems along with proposed solutions.
Conclusions
Under certain conditions, it is possible to obtain a sample with recruitment performance similar to that of other RDS without the need for monetary incentives and using a free access software, considerably reducing costs and allowing its use to be extended to other research groups.
Background
International guidelines suggest hepatitis C virus (HCV) eradication by direct‐acting antivirals (DAAs) after first‐line immunochemotherapy (I‐CT) in patients with HCV‐positive diffuse ...large B‐cell lymphoma (DLBCL), although limited experiences substantiate this recommendation. Moreover, only a few data concerning concurrent administration of DAAs with I‐CT have been reported.
Subjects, Materials, and Methods
We analyzed hematological and virological outcome and survival of 47 consecutive patients with HCV‐positive DLBCL treated at 23 Italian and French centers with DAAs either concurrently (concurrent cohort ConC: n = 9) or subsequently (sequential cohort SeqC: n = 38) to first‐line I‐CT (mainly rituximab, cyclophosphamide, doxorubicin, vincristine and prednisone R‐CHOP‐like).
Results
Median age was 61 years, 89% of patients had stage III/IV, and 25% presented evidence of cirrhosis. Genotype was 1 in 56% and 2 in 34% of cases. Overall, 46 of 47 patients obtained complete response to I‐CT. All patients received appropriate DAAs according to genotype, mainly sofosbuvir‐based regimens (n = 45). Overall, 45 patients (96%) achieved sustained virological response, 8 of 9 in ConC and 37 of 38 in SeqC. DAAs were well tolerated, with only 11 patients experiencing grade 1–2 adverse events. Twenty‐three patients experienced hepatic toxicity (grade 3–4 in seven) following I‐CT in SeqC, compared to only one patient in ConC. At a median follow‐up of 2.8 years, two patients died (2‐year overall survival, 97.4%) and three progressed (2‐year progression‐free survival, 93.1%).
Conclusion
Excellent outcome of this cohort of HCV‐positive DLBCL suggests benefit of HCV eradication by DAAs either after or during I‐CT. Moreover, concurrent DAAs and R‐CHOP administration appeared feasible, effective, and ideally preferable to deferred administration of DAAs for the prevention of hepatic toxicity.
Implications for Practice
Hepatitis C virus (HCV)‐associated diffuse large B‐cell lymphomas (DLBCLs) represent a great therapeutic challenge, especially in terms of hepatic toxicity during immune‐chemotherapy (I‐CT) and long‐term hepatic complications. The advent of highly effective and toxicity‐free direct‐acting antivirals (DAAs) created an exciting opportunity to easily eradicate HCV shortly after or in concomitance with first‐line immunochemotherapy (usually R‐CHOP). This retrospective international study reports the real‐life use of the combination of these two therapeutic modalities either in the concurrent or sequential approach (DAAs after I‐CT) in 47 patients. The favorable reported results on long‐term outcome seem to support the eradication of HCV with DAAs in all patients with HCV‐positive DLBCL. Moreover, the results from the concurrent approach were effective and safe and displayed an advantage in preventing hepatic toxicity during I‐CT.
Epidemiological studies have established that hepatitis C virus (HCV) is associated with diffuse large B‐cell lymphoma (DLBCL). This article reports on patients with HCV‐positive DLBCL treated with direct‐acting antivirals either concurrently or subsequently to a curative‐intent first‐line immunochemotherapy.
An algorithm based on a Bayesian network classifier was adapted to produce 10-day burned area (BA) maps from the Long Term Data Record Version 3 (LTDR) at a spatial resolution of 0.05° (~5 km) for ...the North American boreal region from 2001 to 2011. The modified algorithm used the Brightness Temperature channel from the Moderate Resolution Imaging Spectroradiometer (MODIS) band 31 T31 (11.03 μm) instead of the Advanced Very High Resolution Radiometer (AVHRR) band T3 (3.75 μm). The accuracy of the BA-LTDR, the Collection 5.1 MODIS Burned Area (MCD45A1), the MODIS Collection 5.1 Direct Broadcast Monthly Burned Area (MCD64A1) and the Burned Area GEOLAND-2 (BA GEOLAND-2) products was assessed using reference data from the Alaska Fire Service (AFS) and the Canadian Forest Service National Fire Database (CFSNFD). The linear regression analysis of the burned area percentages of the MCD64A1 product using 40 km × 40 km grids versus the reference data for the years from 2001 to 2011 showed an agreement of R2 = 0.84 and a slope = 0.76, while the BA-LTDR showed an agreement of R2 = 0.75 and a slope = 0.69. These results represent an improvement over the MCD45A1 product, which showed an agreement of R2 = 0.67 and a slope = 0.42. The MCD64A1, BA-LTDR and MCD45A1 products underestimated the total burned area in the study region, whereas the BA GEOLAND-2 product overestimated it by approximately five-fold, with an agreement of R2 = 0.05. Despite MCD64A1 showing the best overall results, the BA-LTDR product proved to be an alternative for mapping burned areas in the North American boreal forest region compared with the other global BA products, even those with higher spatial/spectral resolution.
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