40 research outputs found
The incipient motion of sediment in a channel with model emergent vegetation
No full textIn a bare channel (without vegetation), the incipient velocity for sediment motion, U[subscript crit], has historically been related to the mean bed shear stress ([bar over τ]) o or friction velocity (U[subscript ∗] = √[bar over τ]/ρ). More recent studies, however, suggest turbulence also plays a role. This paper examines whether the onset of sediment motion in a vegetated channel is correlated with U[subscript ∗], or turbulence (k[subscript τ). Images collected with a digital camera were interrogated with a particle-tracking code to measure sediment transport for different vegetation density and channel velocity. The trend in sediment transport with channel velocity was used to identify U[subscript crit] for each stem density. The values of k[subscript τ and U[subscript ∗] were estimated at Ucrit. However, none of these parameters produced a constant threshold across all stem density and bare bed. We construct a new metric representing the peak turbulent velocities impinging on the bed that produces a constant threshold value for all cases
The onset of sediment transport in vegetated channels predicted by turbulent kinetic energy
No full textThis laboratory study advances our understanding of sediment transport in vegetated regions, by describing the impact of stem density on the critical velocity, Ucrit, at which sediment motion is initiated. Sparse emergent vegetation was modeled with rigid cylinders arranged in staggered arrays of different stem densities. The sediment transport rate, Qs, was measured over a range of current speeds using digital imaging, and the critical velocity was selected as the condition at which the magnitude of Qs crossed the noise threshold. For both grain sizes considered here (0.6–0.85 mm and 1.7–2 mm), Ucrit decreased with increasing stem density. This dependence can be explained by a threshold condition based on turbulent kinetic energy, kt, suggesting that near-bed turbulence intensity may be a more important control than bed shear stress on the initiation of sediment motion. The turbulent kinetic energy model unified the bare bed and vegetated channel measurements.National Science Foundation (U.S.) (NSF grant EAR 1414499
Non-local Impacts of Gaps on Submerged Canopy Flow
No full textThe folders include all the Vectrino measurements/records used for the paper, "Non-local Impacts of Gaps on Submerged Canopy Flow". Each folder has the the filtered data with the naming convention, '[gapsize]_[dist downstream]_[z(height from bed].mat'. There are separate folders for Set A and Set B experiments, which separate into the medium and fast flow speeds. There are homogenous measurements as well.</p
Characterizing free-surface expressions of flow instabilities by tracking submerged features
No full textThe Efficacy of the Change in Belly Board Aperture Location by the Addition of Bladder Compression Device for Radiotherapy of Rectal Cancer
No full textGlobal burden of bacterial antimicrobial resistance 1990¿2021: a systematic analysis with forecasts to 2050
No full textBackground: Antimicrobial resistance (AMR) poses an important global health challenge in the 21st century. A previous study has quantified the global and regional burden of AMR for 2019, followed with additional publications that provided more detailed estimates for several WHO regions by country. To date, there have been no studies that produce comprehensive estimates of AMR burden across locations that encompass historical trends and future forecasts. Methods: We estimated all-age and age-specific deaths and disability-adjusted life-years (DALYs) attributable to and associated with bacterial AMR for 22 pathogens, 84 pathogen¿drug combinations, and 11 infectious syndromes in 204 countries and territories from 1990 to 2021. We collected and used multiple cause of death data, hospital discharge data, microbiology data, literature studies, single drug resistance profiles, pharmaceutical sales, antibiotic use surveys, mortality surveillance, linkage data, outpatient and inpatient insurance claims data, and previously published data, covering 520 million individual records or isolates and 19 513 study-location-years. We used statistical modelling to produce estimates of AMR burden for all locations, including those with no data. Our approach leverages the estimation of five broad component quantities: the number of deaths involving sepsis; the proportion of infectious deaths attributable to a given infectious syndrome; the proportion of infectious syndrome deaths attributable to a given pathogen; the percentage of a given pathogen resistant to an antibiotic of interest; and the excess risk of death or duration of an infection associated with this resistance
Antimicrobial resistance burden landscape in Germany in 2019: a comparative country-level estimation
No full textObjectives: Our aim was to present the most comprehensive set of pre-COVID-19 antimicrobial resistance (AMR) burden estimates for Germany to date, with a focus on regional variations and hotspots. Methods: The study estimated deaths and disability-adjusted life-years (DALYs) due to AMR for 23 bacterial pathogens and 88 pathogen-drug combinations in Germany in 2019, with the use of two counterfactual scenarios: deaths attributable to AMR (those that would not have occurred if infections were susceptible) and deaths associated with AMR (cases where AMR was present but not necessarily the cause of death). Models were cross-validated for out-of-sample predictive validity, and uncertainty intervals (UIs) calculated. In stratified analyses we compared death estimates and DALYs with previously published estimates. Results: The total burden of mortality and DALYs associated with AMR in Germany were 45 692 (95% UI, 31 281–64 591) deaths and 752 697 (500 313–1 076 187) DALYs, respectively, with the total burden attributable to AMR 9648 (6520–13 918) deaths and 159 032 (105 021–232 459) DALYs, respectively. Bloodstream, respiratory and intra-abdominal infections were the major contributors to the fatal AMR burden. The leading pathogens responsible for AMR-associated deaths were Escherichia coli, Staphylococcus aureus, Enterococcus faecium, Klebsiella pneumoniae and Pseudomonas aeruginosa. E. coli resistant to β-lactam/β-lactamase inhibitors and aminopenicillin were top pathogen-drug combinations causing deaths attributable to and associated with AMR, respectively. The presented estimates align with previous research. Conclusions: The high resistance levels and significant health burden highlight AMR as a serious public health challenge in Germany, emphasizing the need to further strengthen targeted prevention and control measures against key pathogen-drug combinations
Insights into the burden of bacterial antimicrobial resistance (AMR) in the WHO Eastern Mediterranean Region: a crucial step towards evidence-informed and targeted public health interventions
No full textIntroduction: Antimicrobial resistance (AMR) is a significant but very complex global health issue, making it difficult to accurately determine its full impact. This study aimed to provide the most detailed regional/national estimates of the AMR burden in the WHO Eastern Mediterranean Region. Methods: To estimate deaths and disability-adjusted life years (DALYs) due to AMR for 23 bacterial pathogens and 88 pathogen-drug combinations for 2019 and for the first two years of the COVID-19 pandemic, we utilized data from mortality registries, surveillance systems, hospital records, literature reviews and other sources. A predictive statistical modeling approach - which included five components (the role of infection in deaths, the attribution of infectious deaths to specific syndromes, the proportion of infectious syndrome deaths attributable to specific pathogens, the percentage of pathogen resistant to antibiotics, and the excess risk of mortality associated with this resistance) - was used to integrate this data. We compared the burden in different time periods, and two counterfactual scenarios have been used: deaths/DALYs attributable to AMR and deaths/DALYs associated with AMR. The models were cross-validated to assess out-of-sample predictive validity. Results: The study found that bacterial AMR imposes a significant burden in the WHO Eastern Mediterranean Region, with an estimated 465,000 deaths (95% UI 338,000–621,000) associated with and 124,000 deaths (133,000–220,000) directly attributable to resistance. Respiratory infections emerged as the most significant cause of fatal AMR burden. Six main pathogens – Klebsiella pneumoniae, Escherichia coli, Streptococcus pneumoniae, Staphylococcus aureus, Pseudomonas aeruginosa and Acinetobacter baumannii –accounted for 326,000 deaths associated with AMR. Somalia had the highest AMR burden, with 62.9 deaths (37.4–107.5) attributable to and 223.1 deaths (159.6–309.6) associated with AMR per 100,000 population; conversely, Tunisia had the lowest, with 8.5 deaths (5.1–13.4) attributable to and 34.0 deaths (20.5–53.3) associated with AMR per 100,000 population. The leading pathogen-drug combination burden-wise was methicillin-resistant Staphylococcus aureus, with many other prominent ones. A higher AMR burden was observed in nations with a lower Socio-demographic Index (r = –0.87 [–0.9 to –0.83]). Changes in burden occurred during time, with shifts in leading pathogens during the first two years of the COVID-19 pandemic. Discussion: The substantial number of deaths associated with bacterial AMR underscores the significant public health threat. The high burden observed in countries like Somalia suggests that resource-limited settings may be particularly vulnerable, indicating a need for targeted resource allocation. The predominance of respiratory infections as a prime contributor to AMR-related mortality unveils the need for improving diagnostic/treatment protocols; likewise, time trends and underlying socioeconomic disparities have to be taken into account. Conclusion: To effectively combat AMR in the WHO Eastern Mediterranean Region, strategies must be tailored and targeted to address the specific characteristics of the predominant pathogens and the most critical pathogen-drug combinations
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Global burden associated with 85 pathogens in 2019: a systematic analysis for the Global Burden of Disease Study 2019
No full textBackground Despite a global epidemiological transition towards increased burden of non-communicable diseases, communicable diseases continue to cause substantial morbidity and mortality worldwide. Understanding the burden of a wide range of infectious diseases, and its variation by geography and age, is pivotal to research priority setting and resource mobilisation globally. Methods We estimated disability-adjusted life-years (DALYs) associated with 85 pathogens in 2019, globally, regionally, and for 204 countries and territories. The term pathogen included causative agents, pathogen groups, infectious conditions, and aggregate categories. We applied a novel methodological approach to account for underlying, immediate, and intermediate causes of death, which counted every death for which a pathogen had a role in the pathway to death. We refer to this measure as the burden associated with infection, which was estimated by combining different sources of information. To compare the burden among all pathogens, we used pathogen-specific ratios to incorporate the burden of immediate and intermediate causes of death for pathogens modelled previously by the GBD. We created the ratios by using multiple cause of death data, hospital discharge data, linkage data, and minimally invasive tissue sampling data to estimate the fraction of deaths coming from the pathway to death chain. We multiplied the pathogen-specific ratios by age-specific years of life lost (YLLs), calculated with GBD 2019 methods, and then added the adjusted YLLs to age-specific years lived with disability (YLDs) from GBD 2019 to produce adjusted DALYs to account for deaths in the chain. We used standard GBD methods to calculate 95% uncertainty intervals (UIs) for final estimates of DALYs by taking the 25th and 975th percentiles across 1000 posterior draws for each quantity of interest. We provided burden estimates pertaining to all ages and specifically to the under 5 years age group. Findings Globally in 2019, an estimated 704 million (95% UI 610-820) DALYs were associated with 85 different pathogens, including 309 million (250-377; 439% of the burden) in children younger than 5 years. This burden accounted for 277% (and 655% in those younger than 5 years) of the previously reported total DALYs from all causes in 2019. Comparing super-regions, considerable differences were observed in the estimated pathogen- associated burdens in relation to DALYs from all causes, with the highest burden observed in sub-Saharan Africa (314 million [270-368] DALYs; 615% of total regional burden) and the lowest in the high-income super-region (318 million [254-401] DALYs; 98%). Three leading pathogens were responsible for more than 50 million DALYs each in 2019: tuberculosis (651 million [590-712]), malaria (536 million [270-913]), and HIV or AIDS (521 million [466-609]). Malaria was the leading pathogen for DALYs in children younger than 5 years (372 million [178-642]). We also observed substantial burden associated with previously less recognised pathogens, including Staphylococcus aureus and specific Gram-negative bacterial species (ie, Klebsiella pneumoniae, , Escherichia coli, , Pseudomonas aeruginosa, , Acinetobacter baumannii, , and Helicobacter pylori). ).
Conversely, some pathogens had a burden that was smaller than anticipated. Interpretation Our detailed breakdown of DALYs associated with a comprehensive list of pathogens on a global, regional, and country level has revealed the magnitude of the problem and helps to indicate where research funding mismatch might exist. Given the disproportionate impact of infection on low-income and middle-income countries, an essential next step is for countries and relevant stakeholders to address these gaps by making targeted investments. . Funding Bill & Melinda Gates Foundation, Wellcome Trust, and Department of Health and Social Care using UK aid funding managed by the Fleming Fund. Copyright (c) 2024 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license
