Time-domain numerical simulation of the motion of small floating bodies drifting in waves

Theoretical and experimental investigations have been conducted to examine the behaviour of small icebergs and bergy bits in unidirectional regular waves. A nonlinear time-domain method based on the equivalent motion concept and a corresponding computational algorithm are presented for predicting the motion and trajectory of small ice masses drifting in an open seaway and near a gravity base platform. The general equations of motion of a rigid body are applied, and the wave forces are determined as the sum of the resultant of wave-induced pressures integrated over the instantaneous wetted surface of the body (the Froude-Krylov forces) and the flow disturbance induced by the presence of the body as determined by the equivalent motion method. The algorithm is used to predict the motion and trajectories of free drifting and towed spherical models in small and large amplitude waves. The computed values are found to be in good qualitative and quantitative agreement with the experimental measurements outside the heave resonance range where the motions are over-predicted. The motions of the ice mass are also simulated near a cylindrical gravity platform taking into account the effect of the waves diffracted by the structure. Large heave motions are predicted in close vicinity of the platform. In addition to instances where collisions were predicted, the ice drifted around or maintained a stationary position in front of the structure. It is concluded that the method can be applied to provide predictions of the kinematic parameters of motion of small bodies drifting in waves

Zinc oxide nanoparticles inhibits quorum sensing and virulence in Pseudomonas aeruginosa

Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacterial cell-to-cell communication systems (quorum sensing), which regulate virulence factors production in Pseudomonas aeruginosa, in order to overcome the globalcrisis of antimicrobial resistance.Objectives: Study the potential quorum sensing inhibitory effect of Zinc oxide (ZnO)nanoparticlesin Pseudomonas aeruginosa and the impact on production of virulence factors.Methods: Quorum sensing inhibitory effect of ZnO was evaluated by assessing its ability to reducePseudomonas aeruginosa virulence factors production; rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, qRT-PCR was performed to determine ZnO inhibitory effect onQS-regulatory geneslasI, lasR,rhlI, rhlR, pqsA and pqsR that control virulence factors secretion. Moreover, mice survival test was conducted to investigate the influence of ZnO on Pseudomonas aeruginosa-induced mortality in vivo.Results: ZnO revealed a statistically significant reduction in the production of QS-controlled virulence factors rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, ZnO exhibited a significant decrease in the relative expression of QS-regulatory geneslasI, lasR,rhlI, rhlR,pqsA and pqsR. Additionally, ZnO significantly reduced the pathogenesis of Pseudomonas aeruginosa in vivoConclusion: ZnO nanoparticles can be used as a quorum sensing inhibitor in Pseudomonas aeruginosa infections either as an adjuvant or alternative to conventional antimicrobials.Keywords: Pseudomonas aeruginosa, ZnO, quorum sensing, virulence inhibition

Influence of Melissa officinalis essential oil and its formulation on Typhlodromips swirskii and Neoseiulus barkeri (Acari: Phytoseiidae)

The toxicity of Melissa officinalis L. essential oil and its formulation (Melissacide) were evaluated against eggs and females of two predatory phytoseiid mites, Typhlodromips swirskii (Athias Henriot) and Neoseiulus barkeri (Hughes), using direct spray. Results indicate that both tested materials were potent on predatory females than egg stage. Typhlodromips swirskii was proved to be more sensitive to the oil and formulation than N. barkeri. Females mortality were (62-100%) in T. swirskii, and (46-69%) in N. barkeri, when both predatory mites were sprayed with LC50 and LC90 of the oil and Melissacide reported on Tetranychus urticae Koch. Females of both predators were suffered from reduction in food consumption when sprayed with two sublethal concentrations of Melissacide, while insignificant differences reported in daily number of eggs deposited by females of T. swirskii, when sprayed with its LC25 value of Melissacide and control

Zinc oxide nanoparticles inhibits quorum sensing and virulence in Pseudomonas aeruginosa

Background: Quorum sensing inhibitionis an advanced strategy that aims to interfere with bacterial cell-to-cell communication systems (quorum sensing), which regulate virulence factors production in Pseudomonas aeruginosa, in order to overcome the globalcrisis of antimicrobial resistance. Objectives: Study the potential quorum sensing inhibitory effect of Zinc oxide (ZnO)nanoparticlesin Pseudomonas aeruginosa and the impact on production of virulence factors. Methods: Quorum sensing inhibitory effect of ZnO was evaluated by assessing its ability to reducePseudomonas aeruginosa virulence factors production; rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, qRT-PCR was performed to determine ZnO inhibitory effect onQS-regulatory geneslasI, lasR,rhlI, rhlR, pqsA and pqsR that control virulence factors secretion. Moreover, mice survival test was conducted to investigate the influence of ZnO on Pseudomonas aeruginosa-induced mortality in vivo. Results: ZnO revealed a statistically significant reduction in the production of QS-controlled virulence factors rhamnolipids, pyocyanin, pyoverdin, hemolysins, elastase and proteases. Furthermore, ZnO exhibited a significant decrease in the relative expression of QS-regulatory geneslasI, lasR,rhlI, rhlR,pqsA and pqsR. Additionally, ZnO significantly reduced the pathogenesis of Pseudomonas aeruginosa in vivo Conclusion: ZnO nanoparticles can be used as a quorum sensing inhibitor in Pseudomonas aeruginosa infections either as an adjuvant or alternative to conventional antimicrobials. DOI: https://dx.doi.org/10.4314/ahs.v19i2.28 Cite as: Saleh MM, Sadeq RA, Abdel Latif HK, Abbas HA, Askoura M. Zinc oxide nanoparticles inhibits quorum sensing and virulence in Pseudomonas aeruginosa. Afri Health Sci.2019;19(2): 2043-2055. https://dx.doi.org/10.4314/ahs.v19i2.2

Validity of procalcitonin as diagnostic biomarker for infective endocarditis

Background: Infective endocarditis (IE) is still a fatal infection with high morbidity and mortality. Successful patient outcomes depend on prompt diagnosis and effective therapy. Blood cultures are usually time consuming and sometimes echocardiography is falsely negative. Thus, a straightforward blood test may assist early diagnosis of IE. Multiple studies have revealed that procalcitonin (PCT) was highly associated with bacteremia - the main diagnostic criteria for endocarditis - in patients with fever. Objectives: We aimed to assess the diagnostic significance of procalcitonin concentration in suspected patients of IE. Patients and methods: Twenty-two patients admitted to Assiut University Heart Hospital with a suspicion of IE were enrolled in a prospective study. Based on clinical, microbiological, and echocardiographic findings, Modified duke criteria were applied to the cases to confirm their diagnosis as definite, possible, or rejected IE cases before testing for procalcitonin was done. The study also included fifteen healthy volunteers for comparison with IE patients. Results: Procalcitonin was significantly higher (P-value <0.05) in patients diagnosed as definite and possible IE than with healthy volunteers. The area under the ROC curve was 0.705. At cutoff value of 0.425 ng/ml, the procalcitonin test's sensitivity, specificity, negative predictive value, and positive predictive values were 47.6%, 93.3%, 56%, and 90.9%, respectively. Conclusion: This study implies that procalcitonin may be a valuable supplementary diagnostic marker in IE diagnosis. A threshold value of 0.425 ng/ml should be used for ruling out endocarditis in routine clinical practice and the diagnosis of IE can be strongly excluded below this value

Lablab purpureus—A Crop Lost for Africa?

In recent years, so-called ‘lost crops’ have been appraised in a number of reviews, among them Lablab purpureus in the context of African vegetable species. This crop cannot truly be considered ‘lost’ because worldwide more than 150 common names are applied to it. Based on a comprehensive literature review, this paper aims to put forward four theses, (i) Lablab is one of the most diverse domesticated legume species and has multiple uses. Although its largest agro-morphological diversity occurs in South Asia, its origin appears to be Africa. (ii) Crop improvement in South Asia is based on limited genetic diversity. (iii) The restricted research and development performed in Africa focuses either on improving forage or soil properties mostly through one popular cultivar, Rongai, while the available diversity of lablab in Africa might be under threat of genetic erosion. (iv) Lablab is better adapted to drought than common beans (Phaseolus vulgaris) or cowpea (Vigna unguiculata), both of which have been preferred to lablab in African agricultural production systems. Lablab might offer comparable opportunities for African agriculture in the view of global change. Its wide potential for adaptation throughout eastern and southern Africa is shown with a GIS (geographic information systems) approach

Burnout among surgeons before and during the SARS-CoV-2 pandemic: an international survey

Background: SARS-CoV-2 pandemic has had many significant impacts within the surgical realm, and surgeons have been obligated to reconsider almost every aspect of daily clinical practice. Methods: This is a cross-sectional study reported in compliance with the CHERRIES guidelines and conducted through an online platform from June 14th to July 15th, 2020. The primary outcome was the burden of burnout during the pandemic indicated by the validated Shirom-Melamed Burnout Measure. Results: Nine hundred fifty-four surgeons completed the survey. The median length of practice was 10&nbsp;years; 78.2% included were male with a median age of 37&nbsp;years old, 39.5% were consultants, 68.9% were general surgeons, and 55.7% were affiliated with an academic institution. Overall, there was a significant increase in the mean burnout score during the pandemic; longer years of practice and older age were significantly associated with less burnout. There were significant reductions in the median number of outpatient visits, operated cases, on-call hours, emergency visits, and research work, so, 48.2% of respondents felt that the training resources were insufficient. The majority (81.3%) of respondents reported that their hospitals were included in the management of COVID-19, 66.5% felt their roles had been minimized; 41% were asked to assist in non-surgical medical practices, and 37.6% of respondents were included in COVID-19 management. Conclusions: There was a significant burnout among trainees. Almost all aspects of clinical and research activities were affected with a significant reduction in the volume of research, outpatient clinic visits, surgical procedures, on-call hours, and emergency cases hindering the training. Trial registration: The study was registered on clicaltrials.gov "NCT04433286" on 16/06/2020

Global burden of 369 diseases and injuries in 204 countries and territories, 1990–2019: a systematic analysis for the Global Burden of Disease Study 2019

Background: In an era of shifting global agendas and expanded emphasis on non-communicable diseases and injuries along with communicable diseases, sound evidence on trends by cause at the national level is essential. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) provides a systematic scientific assessment of published, publicly available, and contributed data on incidence, prevalence, and mortality for a mutually exclusive and collectively exhaustive list of diseases and injuries. Methods: GBD estimates incidence, prevalence, mortality, years of life lost (YLLs), years lived with disability (YLDs), and disability-adjusted life-years (DALYs) due to 369 diseases and injuries, for two sexes, and for 204 countries and territories. Input data were extracted from censuses, household surveys, civil registration and vital statistics, disease registries, health service use, air pollution monitors, satellite imaging, disease notifications, and other sources. Cause-specific death rates and cause fractions were calculated using the Cause of Death Ensemble model and spatiotemporal Gaussian process regression. Cause-specific deaths were adjusted to match the total all-cause deaths calculated as part of the GBD population, fertility, and mortality estimates. Deaths were multiplied by standard life expectancy at each age to calculate YLLs. A Bayesian meta-regression modelling tool, DisMod-MR 2.1, was used to ensure consistency between incidence, prevalence, remission, excess mortality, and cause-specific mortality for most causes. Prevalence estimates were multiplied by disability weights for mutually exclusive sequelae of diseases and injuries to calculate YLDs. We considered results in the context of the Socio-demographic Index (SDI), a composite indicator of income per capita, years of schooling, and fertility rate in females younger than 25 years. Uncertainty intervals (UIs) were generated for every metric using the 25th and 975th ordered 1000 draw values of the posterior distribution. Findings: Global health has steadily improved over the past 30 years as measured by age-standardised DALY rates. After taking into account population growth and ageing, the absolute number of DALYs has remained stable. Since 2010, the pace of decline in global age-standardised DALY rates has accelerated in age groups younger than 50 years compared with the 1990–2010 time period, with the greatest annualised rate of decline occurring in the 0–9-year age group. Six infectious diseases were among the top ten causes of DALYs in children younger than 10 years in 2019: lower respiratory infections (ranked second), diarrhoeal diseases (third), malaria (fifth), meningitis (sixth), whooping cough (ninth), and sexually transmitted infections (which, in this age group, is fully accounted for by congenital syphilis; ranked tenth). In adolescents aged 10–24 years, three injury causes were among the top causes of DALYs: road injuries (ranked first), self-harm (third), and interpersonal violence (fifth). Five of the causes that were in the top ten for ages 10–24 years were also in the top ten in the 25–49-year age group: road injuries (ranked first), HIV/AIDS (second), low back pain (fourth), headache disorders (fifth), and depressive disorders (sixth). In 2019, ischaemic heart disease and stroke were the top-ranked causes of DALYs in both the 50–74-year and 75-years-and-older age groups. Since 1990, there has been a marked shift towards a greater proportion of burden due to YLDs from non-communicable diseases and injuries. In 2019, there were 11 countries where non-communicable disease and injury YLDs constituted more than half of all disease burden. Decreases in age-standardised DALY rates have accelerated over the past decade in countries at the lower end of the SDI range, while improvements have started to stagnate or even reverse in countries with higher SDI. Interpretation: As disability becomes an increasingly large component of disease burden and a larger component of health expenditure, greater research and developm nt investment is needed to identify new, more effective intervention strategies. With a rapidly ageing global population, the demands on health services to deal with disabling outcomes, which increase with age, will require policy makers to anticipate these changes. The mix of universal and more geographically specific influences on health reinforces the need for regular reporting on population health in detail and by underlying cause to help decision makers to identify success stories of disease control to emulate, as well as opportunities to improve. Funding: Bill & Melinda Gates Foundation. © 2020 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 licens

Global age-sex-specific fertility, mortality, healthy life expectancy (HALE), and population estimates in 204 countries and territories, 1950-2019 : a comprehensive demographic analysis for the Global Burden of Disease Study 2019

Background: Accurate and up-to-date assessment of demographic metrics is crucial for understanding a wide range of social, economic, and public health issues that affect populations worldwide. The Global Burden of Diseases, Injuries, and Risk Factors Study (GBD) 2019 produced updated and comprehensive demographic assessments of the key indicators of fertility, mortality, migration, and population for 204 countries and territories and selected subnational locations from 1950 to 2019. Methods: 8078 country-years of vital registration and sample registration data, 938 surveys, 349 censuses, and 238 other sources were identified and used to estimate age-specific fertility. Spatiotemporal Gaussian process regression (ST-GPR) was used to generate age-specific fertility rates for 5-year age groups between ages 15 and 49 years. With extensions to age groups 10–14 and 50–54 years, the total fertility rate (TFR) was then aggregated using the estimated age-specific fertility between ages 10 and 54 years. 7417 sources were used for under-5 mortality estimation and 7355 for adult mortality. ST-GPR was used to synthesise data sources after correction for known biases. Adult mortality was measured as the probability of death between ages 15 and 60 years based on vital registration, sample registration, and sibling histories, and was also estimated using ST-GPR. HIV-free life tables were then estimated using estimates of under-5 and adult mortality rates using a relational model life table system created for GBD, which closely tracks observed age-specific mortality rates from complete vital registration when available. Independent estimates of HIV-specific mortality generated by an epidemiological analysis of HIV prevalence surveys and antenatal clinic serosurveillance and other sources were incorporated into the estimates in countries with large epidemics. Annual and single-year age estimates of net migration and population for each country and territory were generated using a Bayesian hierarchical cohort component model that analysed estimated age-specific fertility and mortality rates along with 1250 censuses and 747 population registry years. We classified location-years into seven categories on the basis of the natural rate of increase in population (calculated by subtracting the crude death rate from the crude birth rate) and the net migration rate. We computed healthy life expectancy (HALE) using years lived with disability (YLDs) per capita, life tables, and standard demographic methods. Uncertainty was propagated throughout the demographic estimation process, including fertility, mortality, and population, with 1000 draw-level estimates produced for each metric. Findings: The global TFR decreased from 2·72 (95% uncertainty interval [UI] 2·66–2·79) in 2000 to 2·31 (2·17–2·46) in 2019. Global annual livebirths increased from 134·5 million (131·5–137·8) in 2000 to a peak of 139·6 million (133·0–146·9) in 2016. Global livebirths then declined to 135·3 million (127·2–144·1) in 2019. Of the 204 countries and territories included in this study, in 2019, 102 had a TFR lower than 2·1, which is considered a good approximation of replacement-level fertility. All countries in sub-Saharan Africa had TFRs above replacement level in 2019 and accounted for 27·1% (95% UI 26·4–27·8) of global livebirths. Global life expectancy at birth increased from 67·2 years (95% UI 66·8–67·6) in 2000 to 73·5 years (72·8–74·3) in 2019. The total number of deaths increased from 50·7 million (49·5–51·9) in 2000 to 56·5 million (53·7–59·2) in 2019. Under-5 deaths declined from 9·6 million (9·1–10·3) in 2000 to 5·0 million (4·3–6·0) in 2019. Global population increased by 25·7%, from 6·2 billion (6·0–6·3) in 2000 to 7·7 billion (7·5–8·0) in 2019. In 2019, 34 countries had negative natural rates of increase; in 17 of these, the population declined because immigration was not sufficient to counteract the negative rate of decline. Globally, HALE increased from 58·6 years (56·1–60·8) in 2000 to 63·5 years (60·8–66·1) in 2019. HALE increased in 202 of 204 countries and territories between 2000 and 2019