scholarly journals A global comparison of grassland biomass responses to CO 2 and nitrogen enrichment

2010 ◽  
Vol 365 (1549) ◽  
pp. 2047-2056 ◽  
Author(s):  
Mark Lee ◽  
Pete Manning ◽  
Janna Rist ◽  
Sally A. Power ◽  
Charles Marsh
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
C Sequestration ◽  
Global Scale ◽  
Scale Model ◽  
Published Data ◽  
Climate Data ◽  
Forage Production ◽  
Global Comparison ◽  
N Enrichment

Grassland ecosystems cover vast areas of the Earth's surface and provide many ecosystem services including carbon (C) storage, biodiversity preservation and the production of livestock forage. Predicting the future delivery of these services is difficult, because widespread changes in atmospheric CO 2 concentration, climate and nitrogen (N) inputs are expected. We compiled published data from global change driver manipulation experiments and combined these with climate data to assess grassland biomass responses to CO 2 and N enrichment across a range of climates. CO 2 and N enrichment generally increased aboveground biomass (AGB) but effects of CO 2 enrichment were weaker than those of N. The response to N was also dependent on the amount of N added and rainfall, with a greater response in high precipitation regions. No relationship between response to CO 2 and climate was detected within our dataset, thus suggesting that other site characteristics, e.g. soils and plant community composition, are more important regulators of grassland responses to CO 2 . A statistical model of AGB response to N was used in conjunction with projected N deposition data to estimate changes to future biomass stocks. This highlighted several potential hotspots (e.g. in some regions of China and India) of grassland AGB gain. Possible benefits for C sequestration and forage production in these regions may be offset by declines in plant biodiversity caused by these biomass gains, thus necessitating careful management if ecosystem service delivery is to be maximized. An approach such as ours, in which meta-analysis is combined with global scale model outputs to make large-scale predictions, may complement the results of dynamic global vegetation models, thus allowing us to form better predictions of biosphere responses to environmental change.

scholarly journals TP53 Mutations and Survival in Osteosarcoma Patients: A Meta-Analysis of Published Data

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Zhe Chen ◽  
Jiayi Guo ◽  
Kun Zhang ◽  
Yanxing Guo
Keyword(s):  
Overall Survival ◽  
Prognostic Value ◽  
Large Scale ◽  
Meta Analysis ◽  
Published Data ◽  
Tp53 Mutations ◽  
Study Heterogeneity ◽  
Quantitative Synthesis ◽  
Prospective Trials ◽  
The Relationship

Several research groups have examined the association between TP53 mutations and prognosis in human osteosarcoma. However, the results were controversial. The purpose of this study was to evaluate the prognostic value of TP53 mutations in osteosarcoma patients. A meta-analysis was conducted with all eligible studies which quantitatively evaluated the relationship between TP53 mutations and clinical outcome of osteosarcoma patients. Eight studies with a total of 210 patients with osteosarcoma were included in this meta-analysis. The risk ratio (RR) with a 95% confidence interval (95% CI) was calculated to assess the effect of TP53 mutations on 2-year overall survival. The quantitative synthesis of 8 published studies showed that TP53 mutations were associated with 2-year overall survival in osteosarcoma patients. These data suggested that TP53 mutations had an unfavorable impact on 2-year overall survival when compared to the counterparts with wild type (WT) TP53 (RR: 1.79; 95% CI: 1.12 to 2.84;P=0.01;I2=0%). There was no between-study heterogeneity. TP53 mutations are an effective prognostic marker for survival of patients with osteosarcoma. However, further large-scale prospective trials should be performed to clarify the prognostic value of TP53 mutations on 3- or 5-year survival in osteosarcoma patients.

scholarly journals GMD perspective: The quest to improve the evaluation of groundwater representation in continental- to global-scale models

2021 ◽  
Vol 14 (12) ◽  
pp. 7545-7571
Author(s):  
Tom Gleeson ◽  
Thorsten Wagener ◽  
Petra Döll ◽  
Samuel C. Zipper ◽  
Charles West ◽  
...  
Keyword(s):  
Model Evaluation ◽  
Land Surface ◽  
Large Scale ◽  
Groundwater Resources ◽  
Regional Scale ◽  
Global Scale ◽  
Expert Elicitation ◽  
Data Availability ◽  
Scale Model ◽  
Scale Models

Abstract. Continental- to global-scale hydrologic and land surface models increasingly include representations of the groundwater system. Such large-scale models are essential for examining, communicating, and understanding the dynamic interactions between the Earth system above and below the land surface as well as the opportunities and limits of groundwater resources. We argue that both large-scale and regional-scale groundwater models have utility, strengths, and limitations, so continued modeling at both scales is essential and mutually beneficial. A crucial quest is how to evaluate the realism, capabilities, and performance of large-scale groundwater models given their modeling purpose of addressing large-scale science or sustainability questions as well as limitations in data availability and commensurability. Evaluation should identify if, when, or where large-scale models achieve their purpose or where opportunities for improvements exist so that such models better achieve their purpose. We suggest that reproducing the spatiotemporal details of regional-scale models and matching local data are not relevant goals. Instead, it is important to decide on reasonable model expectations regarding when a large-scale model is performing “well enough” in the context of its specific purpose. The decision of reasonable expectations is necessarily subjective even if the evaluation criteria are quantitative. Our objective is to provide recommendations for improving the evaluation of groundwater representation in continental- to global-scale models. We describe current modeling strategies and evaluation practices, and we subsequently discuss the value of three evaluation strategies: (1) comparing model outputs with available observations of groundwater levels or other state or flux variables (observation-based evaluation), (2) comparing several models with each other with or without reference to actual observations (model-based evaluation), and (3) comparing model behavior with expert expectations of hydrologic behaviors in particular regions or at particular times (expert-based evaluation). Based on evolving practices in model evaluation as well as innovations in observations, machine learning, and expert elicitation, we argue that combining observation-, model-, and expert-based model evaluation approaches, while accounting for commensurability issues, may significantly improve the realism of groundwater representation in large-scale models, thus advancing our ability for quantification, understanding, and prediction of crucial Earth science and sustainability problems. We encourage greater community-level communication and cooperation on this quest, including among global hydrology and land surface modelers, local to regional hydrogeologists, and hydrologists focused on model development and evaluation.

scholarly journals Association between epilepsy and challenging behaviour in adults with intellectual disabilities: systematic review and meta-analysis

BJPsych Open ◽  
2020 ◽  
Vol 6 (5) ◽  
Author(s):  
Shoumitro Deb ◽  
Basma Akrout Brizard ◽  
Bharati Limbu
Keyword(s):  
Systematic Review ◽  
Intellectual Disabilities ◽  
Large Scale ◽  
Meta Analysis ◽  
Effect Sizes ◽  
Published Data ◽  
Challenging Behaviour ◽  
Intergroup Difference ◽  
Significant Intergroup Difference ◽  
Adults With Intellectual Disabilities

Background Previous systematic reviews showed no significant association between epilepsy and challenging behaviours in adults with intellectual disabilities. Aims To identify whether there is an association between epilepsy and challenging behaviour in adults with intellectual disabilities by carrying out a systematic review of published data. PROSPERO registration number: CRD42020178092. Method We searched five databases and hand-searched six journals. Two authors independently screened titles, abstracts and full articles using a standardised eligibility checklist. Several meta-analyses were carried out. Results The narrative analysis of data from 34 included articles (14 168 adults with intellectual disabilities, 4781 of whom also had epilepsy) showed no significant association between epilepsy and challenging behaviour. Meta-analysis was possible on data from 16 controlled studies. This showed no significant intergroup difference but after sensitivity analysis meta-analysis of 10 studies showed a significantly higher rate of overall challenging behaviour in the epilepsy group (effect size: 0.16) compared with the non-epilepsy group. Aggression and self-injurious behaviour both showed a statistically significant higher rate in the epilepsy group, with very small effect sizes (0.16 and 0.28 respectively). No significant intergroup difference was observed in the rate of stereotypy. Conclusions The findings are contradictory and must be interpreted with caution because of the difficulty in pooling data from varied studies, which is likely to introduce confounding. Where significant differences were found, effect sizes are small and may not be clinically significant, and there are major methodological flaws in the included studies, which should be addressed in future large-scale properly controlled studies.

scholarly journals Application of an improved global-scale groundwater model for water table estimation across New Zealand

2018 ◽  
Author(s):  
Rogier Westerhoff ◽  
Paul White ◽  
Gonzalo Miguez-Macho
Keyword(s):  
New Zealand ◽  
Water Table ◽  
Input Data ◽  
Large Scale ◽  
Hydraulic Head ◽  
Global Scale ◽  
Scale Model ◽  
Catchment Scale ◽  
Scale Models ◽  
Model Equations

Abstract. Many studies underline the importance of groundwater assessment at the larger, i.e., global, scale. The large-scale models used for these assessments are often simplified and typically not used for smaller-scale, i.e., catchment-scale, studies, because hydrology and water policy are traditionally best constrained at the catchment scale, and because large-scale models are too uncertain for that scale. However, smaller-scale groundwater models can still have considerable uncertainty, especially in data-sparse areas. There is a potential for larger-scale models to constrain the uncertainty for small-scale models. That is because they can provide an extra source of information in data-sparse areas, such as the initial estimate of hydraulic head. Large-scale models, often quick and simple, can thus take away some of the computational burden of local and more sophisticated applications. The problem of this approach is that model uncertainty of large-scale models is often too large, because the quality of their, coarse and global-scale, input data is large, and often inconsistent with the input data of local models. What is needed is an approach where large-scale and local models can meet in the middle. This study uses an existing, global-scale, groundwater flow model. It feeds that model with national input data of New Zealand terrain, geology, and recharge. It then builds the first New-Zealand national-scale groundwater model. The resulting nationwide maps of hydraulic head and water table depths show that the model points out the main alluvial aquifers with fine spatial detail (200m grid resolution). The national input data and finer spatial detail result in better and more realistic variations of water table depth than the original, global-scale, model outputs. In two regional case studies in New Zealand, the hydraulic head matches the available groundwater level data well. The nationwide water tables show that the model is mostly driven by the elevation (gravity) and impeded by the geology (permeability). The use of this first New Zealand-wide model can aid in provision of water table estimates in data-sparse regions. The national model can also be used to solve inconsistency of models in areas of trans-boundary aquifers, i.e., aquifers that cover more than one region in New Zealand. Shortcomings of the model are caused by the simplified model properties, but also by the accuracy of input data. Future research should therefore not only focus on further improvements of model equations, but also improved estimation of hydraulic conductivity and the digital elevation model, especially in areas of shallow groundwater level. We further surmise that the findings of this study, i.e., application of a global-scale models at smaller-scales, will lead to subsequent improvement of the global-scale model equations.

scholarly journals Global prevalence of dyslipidaemia in adult populations: a systematic review protocol

BMJ Open ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. e049662
Author(s):  
Mohamed-Syarif Mohamed-Yassin ◽  
Noorhida Baharudin ◽  
Suraya Abdul-Razak ◽  
Anis Safura Ramli ◽  
Nai Ming Lai
Keyword(s):  
Systematic Review ◽  
Large Scale ◽  
Meta Analysis ◽  
Therapeutic Interventions ◽  
Point Estimate ◽  
Published Data ◽  
Cochrane Central Register ◽  
Global Prevalence ◽  
Study Results ◽  
Prevalence Estimates

IntroductionDyslipidaemia is one of the established risk factors for cardiovascular disease. Evidence from large-scale trials showed that effective treatment of dyslipidaemia can reduce all-cause and coronary mortality. To date, there is no published systematic review on the worldwide prevalence of dyslipidaemia in adults. We propose to perform a systematic review on the global prevalence of dyslipidaemia in adults 18 years and older.Methods and analysisWe will identify observational studies through comprehensive literature searches. We will search: MEDLINE, Cochrane Central Register of Controlled Trials for published studies and trial registries including the WHO International Trial Registry Platform and ClinicalTrials.gov. Two reviewers will independently screen the titles and abstracts, attain full text of eligible articles, extract data, and appraise the quality and bias of the included studies. Disagreement among the authors will be resolved by discussion leading to a consensus. Next, we will perform a narrative synthesis of the study results. Study heterogeneity will be assessed using I2 statistics. If I2 is high (≥75%), and plausible heterogeneity contributors are found, we will divide the studies into appropriate subgroups for pooling of results or assess the association of plausible covariates and the prevalence estimates using meta-regression. If I2<75%, we will undertake meta-analysis using the random-effects model and transform all prevalence estimates using the Freeman-Tukey transformation for pooling, to obtain a synthesised point estimate of prevalence with its 95% confidence. We will then back-transform the point estimate, and report our results using the back-transformed figures.Ethics and disseminationEthics approval is not a requirement as this study is based on available published data. Results of this systematic review will be presented at conferences, shared with relevant health authorities, and published in a peer-reviewed journal. These results may help quantify the magnitude of dyslipidaemia globally, and guide preventative and therapeutic interventions.PROSPERO registration numberCRD42020200281

scholarly journals GMD Perspective: the quest to improve the evaluation of groundwater representation in continental to global scale models

2021 ◽  
Author(s):  
Tom Gleeson ◽  
Thorsten Wagener ◽  
Petra Döll ◽  
Samuel C. Zipper ◽  
Charles West ◽  
...  
Keyword(s):  
Model Evaluation ◽  
Land Surface ◽  
Large Scale ◽  
Groundwater Resources ◽  
Regional Scale ◽  
Global Scale ◽  
Expert Elicitation ◽  
Data Availability ◽  
Scale Model ◽  
Scale Models

Abstract. Continental- to global-scale hydrologic and land surface models increasingly include representations of the groundwater system. Such large-scale models are essential for examining, communicating, and understanding the dynamic interactions between the Earth System above and below the land surface as well as the opportunities and limits of groundwater resources. We argue that both large-scale and regional-scale groundwater models have utility, strengths and limitations so continued modeling at both scales is essential and mutually beneficial. A crucial quest is how to evaluate the realism, capabilities and performance of large-scale groundwater models given their modeling purpose of addressing large-scale science or sustainability questions as well as limitations in data availability and commensurability. Evaluation should identify if, when or where large-scale models achieve their purpose or where opportunities for improvements exists so that such models better achieve their purpose. We suggest that reproducing the spatio-temporal details of regional-scale models and matching local data is not a relevant goal. Instead, it is important to decide on reasonable model expectations regarding when a large scale model is performing “well enough” in the context of its specific purpose. The decision of reasonable expectations is necessarily subjective even if the evaluation criteria is quantitative. Our objective is to provide recommendations for improving the evaluation of groundwater representation in continental- to global-scale models. We describe current modeling strategies and evaluation practices, and subsequently discuss the value of three evaluation strategies: 1) comparing model outputs with available observations of groundwater levels or other state or flux variables (observation-based evaluation); 2) comparing several models with each other with or without reference to actual observations (model-based evaluation); and 3) comparing model behavior with expert expectations of hydrologic behaviors in particular regions or at particular times (expert-based evaluation). Based on evolving practices in model evaluation as well as innovations in observations, machine learning and expert elicitation, we argue that combining observation-, model-, and expert-based model evaluation approaches, while accounting for commensurability issues, may significantly improve the realism of groundwater representation in large-scale models. Thus advancing our ability for quantification, understanding, and prediction of crucial Earth science and sustainability problems. We encourage greater community-level communication and cooperation on this quest, including among global hydrology and land surface modelers, local to regional hydrogeologists, and hydrologists focused on model development and evaluation.

Relationship between total plasma homocysteine and the risk of aneurysms – a meta-analysis

VASA ◽  
2020 ◽  
pp. 1-6
Author(s):  
Hanji Zhang ◽  
Dexin Yin ◽  
Yue Zhao ◽  
Yezhou Li ◽  
Dejiang Yao ◽  
...  
Keyword(s):  
Large Scale ◽  
Meta Analysis ◽  
Single Species ◽  
Total Plasma ◽  
Control Groups ◽  
Randomized Controlled ◽  
Randomized Controlled Studies ◽  
The Difference ◽  
The Relationship ◽  
Healthy Participants

Summary: Our meta-analysis focused on the relationship between homocysteine (Hcy) level and the incidence of aneurysms and looked at the relationship between smoking, hypertension and aneurysms. A systematic literature search of Pubmed, Web of Science, and Embase databases (up to March 31, 2020) resulted in the identification of 19 studies, including 2,629 aneurysm patients and 6,497 healthy participants. Combined analysis of the included studies showed that number of smoking, hypertension and hyperhomocysteinemia (HHcy) in aneurysm patients was higher than that in the control groups, and the total plasma Hcy level in aneurysm patients was also higher. These findings suggest that smoking, hypertension and HHcy may be risk factors for the development and progression of aneurysms. Although the heterogeneity of meta-analysis was significant, it was found that the heterogeneity might come from the difference between race and disease species through subgroup analysis. Large-scale randomized controlled studies of single species and single disease species are needed in the future to supplement the accuracy of the results.

RANCANG BANGUN PERANGKAT EKSPERIMENTASI PROSES PIROLISIS BIOMASA GELOMBANG MIKRO

2013 ◽  
Vol 14 (2) ◽  
Author(s):  
Noor Fachrizal
Keyword(s):  
Large Scale ◽  
Continuous Model ◽  
Biomass Energy ◽  
Scale Model ◽  
Small Scale ◽  
Laboratory Apparatus ◽  
Liquid Form ◽  
Large Scale Model ◽  
Bio Oil ◽  
Pyrolysis Of Biomass

Biomass such as agriculture waste and urban waste are enormous potency as energy resources instead of enviromental problem. organic waste can be converted into energy in the form of liquid fuel, solid, and syngas by using of pyrolysis technique. Pyrolysis process can yield higher liquid form when the process can be drifted into fast and flash response. It can be solved by using microwave heating method. This research is started from developing an experimentation laboratory apparatus of microwave-assisted pyrolysis of biomass energy conversion system, and conducting preliminary experiments for gaining the proof that this method can be established for driving the process properly and safely. Modifying commercial oven into laboratory apparatus has been done, it works safely, and initial experiments have been carried out, process yields bio-oil and charcoal shortly, several parameters are achieved. Some further experiments are still needed for more detail parameters. Theresults may be used to design small-scale continuous model of productionsystem, which then can be developed into large-scale model that applicable for comercial use.

Identification of and Correction for Publication Bias: Comment

2019 ◽  
Author(s):  
Amanda Kvarven ◽  
Eirik Strømland ◽  
Magnus Johannesson
Keyword(s):  
Publication Bias ◽  
False Positive ◽  
Large Scale ◽  
Meta Analysis ◽  
False Positive Rate ◽  
Effect Sizes ◽  
Replication Studies ◽  
Moderate Reduction ◽  
Positive Rate ◽  
Meta Analyses

Andrews &amp; Kasy (2019) propose an approach for adjusting effect sizes in meta-analysis for publication bias. We use the Andrews-Kasy estimator to adjust the result of 15 meta-analyses and compare the adjusted results to 15 large-scale multiple labs replication studies estimating the same effects. The pre-registered replications provide precisely estimated effect sizes, which do not suffer from publication bias. The Andrews-Kasy approach leads to a moderate reduction of the inflated effect sizes in the meta-analyses. However, the approach still overestimates effect sizes by a factor of about two or more and has an estimated false positive rate of between 57% and 100%.

Sign in / Sign up

Export Citation Format

Share Document