Height-diameter allometry of tropical forest trees

Copyright © 2011 European Geosciences Union. This is the published version available at http://www.biogeosciences.net/8/1081/2011/bg-8-1081-2011.html doi:10.5194/bg-8-1081-2011Tropical tree height-diameter (H:D) relationships may vary by forest type and region making large-scale estimates of above-ground biomass subject to bias if they ignore these differences in stem allometry. We have therefore developed a new global tropical forest database consisting of 39 955 concurrent H and D measurements encompassing 283 sites in 22 tropical countries. Utilising this database, our objectives were: 1. to determine if H:D relationships differ by geographic region and forest type (wet to dry forests, including zones of tension where forest and savanna overlap). 2. to ascertain if the H:D relationship is modulated by climate and/or forest structural characteristics (e.g. stand-level basal area, A). 3. to develop H:D allometric equations and evaluate biases to reduce error in future local-to-global estimates of tropical forest biomass. Annual precipitation coefficient of variation (PV), dry season length (SD), and mean annual air temperature (TA) emerged as key drivers of variation in H:D relationships at the pantropical and region scales. Vegetation structure also played a role with trees in forests of a high A being, on average, taller at any given D. After the effects of environment and forest structure are taken into account, two main regional groups can be identified. Forests in Asia, Africa and the Guyana Shield all have, on average, similar H:D relationships, but with trees in the forests of much of the Amazon Basin and tropical Australia typically being shorter at any given D than their counterparts elsewhere. The region-environment-structure model with the lowest Akaike's information criterion and lowest deviation estimated stand-level H across all plots to within amedian −2.7 to 0.9% of the true value. Some of the plot-to-plot variability in H:D relationships not accounted for by this model could be attributed to variations in soil physical conditions. Other things being equal, trees tend to be more slender in the absence of soil physical constraints, especially at smaller D. Pantropical and continental-level models provided less robust estimates of H, especially when the roles of climate and stand structure in modulating H:D allometry were not simultaneously taken into account

Human cytomegalovirus immediate-early 1 protein rewires upstream STAT3 to downstream STAT1 signaling switching an IL6-type to an IFNγ-like response

MN and CP were supported by the Wellcome Trust (www.wellcome.ac.uk) Institutional Strategic Support Fund and CP was supported by the Deutsche Forschungsgemeinschaft (PA 815/2-1; www.dfg.de).The human cytomegalovirus (hCMV) major immediate-early 1 protein (IE1) is best known for activating transcription to facilitate viral replication. Here we present transcriptome data indicating that IE1 is as significant a repressor as it is an activator of host gene expression. Human cells induced to express IE1 exhibit global repression of IL6- and oncostatin M-responsive STAT3 target genes. This repression is followed by STAT1 phosphorylation and activation of STAT1 target genes normally induced by IFNγ. The observed repression and subsequent activation are both mediated through the same region (amino acids 410 to 445) in the C-terminal domain of IE1, and this region serves as a binding site for STAT3. Depletion of STAT3 phenocopies the STAT1-dependent IFNγ-like response to IE1. In contrast, depletion of the IL6 receptor (IL6ST) or the STAT kinase JAK1 prevents this response. Accordingly, treatment with IL6 leads to prolonged STAT1 instead of STAT3 activation in wild-type IE1 expressing cells, but not in cells expressing a mutant protein (IE1dl410-420) deficient for STAT3 binding. A very similar STAT1-directed response to IL6 is also present in cells infected with a wild-type or revertant hCMV, but not an IE1dl410-420 mutant virus, and this response results in restricted viral replication. We conclude that IE1 is sufficient and necessary to rewire upstream IL6-type to downstream IFNγ-like signaling, two pathways linked to opposing actions, resulting in repressed STAT3- and activated STAT1-responsive genes. These findings relate transcriptional repressor and activator functions of IE1 and suggest unexpected outcomes relevant to viral pathogenesis in response to cytokines or growth factors that signal through the IL6ST-JAK1-STAT3 axis in hCMV-infected cells. Our results also reveal that IE1, a protein considered to be a key activator of the hCMV productive cycle, has an unanticipated role in tempering viral replication.Publisher PDFPeer reviewe

Tree height integrated into pantropical forest biomass estimates

Copyright © 2012 European Geosciences Union. This is the published version available at http://www.biogeosciences.net/9/3381/2012/bg-9-3381-2012.htmlAboveground tropical tree biomass and carbon storage estimates commonly ignore tree height (H). We estimate the effect of incorporating H on tropics-wide forest biomass estimates in 327 plots across four continents using 42 656 H and diameter measurements and harvested trees from 20 sites to answer the following questions: 1. What is the best H-model form and geographic unit to include in biomass models to minimise site-level uncertainty in estimates of destructive biomass? 2. To what extent does including H estimates derived in (1) reduce uncertainty in biomass estimates across all 327 plots? 3. What effect does accounting for H have on plot- and continental-scale forest biomass estimates? The mean relative error in biomass estimates of destructively harvested trees when including H (mean 0.06), was half that when excluding H (mean 0.13). Power- and Weibull-H models provided the greatest reduction in uncertainty, with regional Weibull-H models preferred because they reduce uncertainty in smaller-diameter classes (≤40 cm D) that store about one-third of biomass per hectare in most forests. Propagating the relationships from destructively harvested tree biomass to each of the 327 plots from across the tropics shows that including H reduces errors from 41.8 Mg ha−1 (range 6.6 to 112.4) to 8.0 Mg ha−1 (−2.5 to 23.0). For all plots, aboveground live biomass was −52.2 Mg ha−1 (−82.0 to −20.3 bootstrapped 95% CI), or 13%, lower when including H estimates, with the greatest relative reductions in estimated biomass in forests of the Brazilian Shield, east Africa, and Australia, and relatively little change in the Guiana Shield, central Africa and southeast Asia. Appreciably different stand structure was observed among regions across the tropical continents, with some storing significantly more biomass in small diameter stems, which affects selection of the best height models to reduce uncertainty and biomass reductions due to H. After accounting for variation in H, total biomass per hectare is greatest in Australia, the Guiana Shield, Asia, central and east Africa, and lowest in east-central Amazonia, W. Africa, W. Amazonia, and the Brazilian Shield (descending order). Thus, if tropical forests span 1668 million km2 and store 285 Pg C (estimate including H), then applying our regional relationships implies that carbon storage is overestimated by 35 Pg C (31–39 bootstrapped 95% CI) if H is ignored, assuming that the sampled plots are an unbiased statistical representation of all tropical forest in terms of biomass and height factors. Our results show that tree H is an important allometric factor that needs to be included in future forest biomass estimates to reduce error in estimates of tropical carbon stocks and emissions due to deforestation

High Quality Care and Ethical Pay-for-Performance: A Society of General Internal Medicine Policy Analysis

BACKGROUND: Pay-for-performance is proliferating, yet its impact on key stakeholders remains uncertain. OBJECTIVE: The Society of General Internal Medicine systematically evaluated ethical issues raised by performance-based physician compensation. RESULTS: We conclude that current arrangements are based on fundamentally acceptable ethical principles, but are guided by an incomplete understanding of health-care quality. Furthermore, their implementation without evidence of safety and efficacy is ethically precarious because of potential risks to stakeholders, especially vulnerable patients. CONCLUSION: We propose four major strategies to transition from risky pay-for-performance systems to ethical performance-based physician compensation and high quality care. These include implementing safeguards within current pay-for-performance systems, reaching consensus regarding the obligations of key stakeholders in improving health-care quality, developing valid and comprehensive measures of health-care quality, and utilizing a cautious evaluative approach in creating the next generation of compensation systems that reward genuine quality

Polyp measurement based on CT colonography and colonoscopy: variability and systematic differences

To assess the variability and systematic differences in polyp measurements on optical colonoscopy and CT colonography. Gastroenterologists measured 51 polyps by visual estimation, forceps comparison and linear probe. CT colonography observers randomly assessed polyp size two-dimensionally (abdominal and intermediate window) and three-dimensionally (manually and semi-automatically). Linear mixed models were used to assess the variability and systematic differences between CT colonography and optical colonoscopy techniques. The variability of forceps and linear probe measurements was comparable and both showed less variability than measurement by visual assessment. Measurements by linear probe were 0.7 mm smaller than measurements by visual assessment or by forceps. The variability of all CT colonography techniques was lower than for measurements by forceps or visual assessment and sometimes lower (only 2D intermediate window and manual 3D) compared with measurements by linear probe. All CT colonography measurements judged polyps to be larger than optical colonoscopy, with differences ranging from 0.7 to 2.3 mm. A linear probe does not reduce the measurement variability of endoscopists compared with the forceps. Measurement differences between observers on CT colonography were usually smaller than at optical colonoscopy. Polyps appeared larger when using various CT colonography techniques than when measured during optical colonoscop

Erythropoietin Improves the Survival of Fat Tissue after Its Transplantation in Nude Mice

Background: Autologous transplanted fat has a high resorption rate, providing a clinical challenge for the means to reduce it. Erythropoietin (EPO) has non-hematopoietic targets, and we hypothesized that EPO may improve long-term fat graft survival because it has both pro-angiogenic and anti-apoptotic properties. We aimed to determine the effect of EPO on the survival of human fat tissue after its transplantation in nude mice. Methodology/Principal Findings: Human fat tissue was injected subcutaneously into immunologically-compromised nude mice, and the grafts were then treated with either 20 IU or 100 IU EPO. At the end of the 15-week study period, the extent of angiogenesis, apoptosis, and histology were assessed in the fat grafts. The results were compared to vascular endothelial growth factor (VEGF)-treated and phosphate-buffered saline (PBS)-treated fat grafts. The weight and volume of the EPOtreated grafts were higher than those of the PBS-treated grafts, whose weights and volumes were not different from those of the VEGF-treated grafts. EPO treatment also increased the expression of angiogenic factors and microvascular density, and reduced inflammation and apoptosis in a dose-dependent manner in the fat grafts. Conclusions/Significance: Our data suggest that stimulation of angiogenesis by a cluster of angiogenic factors and decreased fat cell apoptosis account for potential mechanisms that underlie the improved long-term survival of fa

Comparative Performance Information Plays No Role in the Referral Behaviour of GPs

Comparative performance information (CPI) about the quality of hospital care is information used to identify high-quality hospitals and providers. As the gatekeeper to secondary care, the general practitioner (GP) can use CPI to reflect on the pros and cons of the available options with the patient and choose a provider best fitted to the patient’s needs. We investigated how GPs view their role in using CPI to choose providers and support patients. Method: We used a mixed-method, sequential, exploratory design to conduct explorative interviews with 15 GPs about their referral routines, methods of referral consideration, patient involvement, and the role of CPI. Then we quantified the qualitative results by sending a survey questionnaire to 81 GPs affiliated with a representative national research network. Results: Seventy GPs (86% response rate) filled out the questionnaire. Most GPs did not know where to find CPI (87%) and had never searched for it (94%). The GPs reported that they were not motivated to use CPI due to doubts about its role as support information, uncertainty about the effect of using CPI, lack of faith in better outcomes, and uncertainty about CPI content and validity. Nonetheless, most GPs believed that patients would like to be informed about quality-of- care differences (62%), and about half the GPs discussed quality-of-care differences with their patients (46%), though these discussions were not based on CPI. Conclusion: Decisions about referrals to hospital care are not based on CPI exchanges during GP consultations. As a gatekeeper, the GP is in a good position to guide patients through the enormous amount of quality information that is available. Nevertheless, it is unclear how and whether the GP’s role in using information about quality of care in the referral process can grow, as patients hardly ever initiate a discussion based on CPI, though they seem to be increasingly more critical about differences in quality of care. Future research should address the conditions needed to support GPs’ ability and willingness to use CPI to guide their patients in the referral process

Diagnostic accuracy of contrast-enhanced MR angiography in severe carotid stenosis: meta-analysis with metaregression of different techniques

Contrast-enhanced magnetic resonance angiography (CE-MRA) has become a well-established noninvasive imaging method for the assessment of severe carotid stenosis (70–99% by NASCET criteria). However, CE-MRA is not a standardised technique, but encompasses different concurrent techniques. This review analyses possible differences. A bivariate random effects meta-analysis of 17 primary diagnostic accuracy studies confirmed a high pooled sensitivity of 94.3% and specificity of 93.0% for carotid CE-MRA in severe carotid stenosis. Sensitivity was fairly uniform among the studies, while specificity showed significant variation (I2 = 73%). Metaregressions found significant differences for specificity with two covariates: specificity was higher when using not only maximum intensity projection (MIP) images, but also three-dimensional (3D) images (P = 0.01). Specificity was also higher with electronic images than with hardcopies (P = 0.02). The timing technique (bolus-timed, fluoroscopically triggered or time-resolved) did not result in any significant differences in diagnostic accuracy. Some nonsignificant trends were found for the percentages of severe carotid disease, acquisition time and voxel size. In conclusion, in CE-MRA of severe carotid stenosis the three major timing techniques yield comparably high diagnostic accuracy, electronic images are more specific than hardcopies, and 3D images should be used in addition to MIP images to increase the specificity

The value of postmortem computed tomography as an alternative for autopsy in trauma victims: a systematic review

The aim of this study was to assess the role of postmortem computed tomography (PMCT) as an alternative for autopsy in determining the cause of death and the identification of specific injuries in trauma victims. A systematic review was performed by searching the EMBASE and MEDLINE databases. Articles were eligible if they reported both PMCT as well as autopsy findings and included more than one trauma victim. Two reviewers independently assessed the eligibility and quality of the articles. The outcomes were described in terms of the percentage agreement on causes of death and amount of injuries detected. The data extraction and analysis were performed together. Fifteen studies were included describing 244 victims. The median sample size was 13 (range 5–52). The percentage agreement on the cause of death between PMCT and autopsy varied between 46 and 100%. The overall amount of injuries detected on CT ranged from 53 to 100% compared with autopsy. Several studies suggested that PMCT was capable of identifying injuries not detected during normal autopsy. This systematic review provides inconsistent evidence as to whether PMCT is a reliable alternative for autopsy in trauma victims. PMCT has promising features in postmortem examination suggesting PMCT is a good alternative for a refused autopsy or a good adjunct to autopsy because it detects extra injuries overseen during autopsies. To examine the value of PMCT in trauma victims there is a need for well-designed and larger prospective studies