DC microgrid simulation and control

However, one of the primary challenges in the microgrid is controlling power electronic devices when it is coordinated with the utility grid. The control system in the microgrid has the main objectives, to ensure supply power to the critical loads, to connect and disconnect the load in case of any fault occurring in the microgrid. This thesis investigates different types of strategies used to control and manage a microgrid; also, the report considers inverter control in islanded mode. This thesis explores the ideas for controlling a microgrid in terms of voltage control in both centralized and decentralized configurations. In more detail, simulations were carried out on two control strategies; inverter control, and frequency control. The inverter control method having the ability to bring the stable and efficient electricity to microgrid system has attracted much consideration in recent years. The droop controller had the capability to autonomously perform equal power sharing and maintain stability in islanded mode of operation. There are many existing dc microgrid around the world. Kythnos Island microgrid is one of those existing microgrid, which can supply 12 houses within the island by using the inverter controller, as the utility grid is located far away from the microgrid. However, this island is either ac or dc loads, so some inverters and converters will be involved in the network. The investigation used MATLAB /SIMULINK to simulate the microgrid network. Which done by implementing the controller in the both ac and dc load. The performance measures such as power sharing accuracy between the microgrid and diesel generator will be obtained. The diesel generators used as a backup in the case of any fault occur in the microgrid. The network simulations at different dc and ac loads will be simulating by using Simulink. This then used to calculate the efficiency of the whole network through the Simulink. Then how efficiency is can be used to upgrade the network as future scope. Active and reactive power in the droop control has been commonly reported on and has been shown to work over a series of the condition of the network. The PQ inverter improves the performance of microgrid in islanded mode; however, the result demonstrates that the inverter controller performed well in the simulation of the Kythnos microgrid network. The efficiency of the LVDC indicates that inverter controller with the ac load performance higher efficiency compared to the dc loads

Attenuated PTH Responsiveness to Vitamin D Deficiency among Patients with Type 2 Diabetes and Chronic Hyperglycemia

Background The short and long-term relationship between hyperglycemia and PTH level among patients suffering from both diabetes type 2 and vitamin D deficiency were evaluated. Methods This was a cross sectional study performed at Dubai Diabetes Center, UAE. To demonstrate the relationship between hyperglycemia and PTH level, subjects with type 2 diabetes and vitamin D deficiency (124 adults) were divided into 4 groups based on their FPG and HbA1c levels. Results Mean vitamin D and PTH levels among subjects with HbA1c ≤ 7% (53 mmol/mol) were 14.05 ng/ml and 19.51 pg/ml respectively. On the other hand, mean vitamin D and PTH levels among subjects with HbA1c ≥ 10% (86 mmol/mol) were significantly lower at 11.77 ng/ml and 17.75 pg/ml respectively. The product of vitamin D and PTH among subjects with an HbA1c ≤ 7% (53 mmol/mol) was 250.380, compared with only 197.710 among subjects with HbA1c ≥ 10 (86 mmol/mol). Regression analysis for subjects older than 50 years shows a significant negative effect of HbA1c on the PTH level. Mean calcium level among subjects with HbA1c ≤ 7% (53 mmol/mol) was 8.80 mg/dl compared with 8.94 mg/dl when HbA1c is ≥10% (86 mmol/mol) with no statistical difference. Although high FPG was associated with a lower PTH level, such association was not statistically significant. Conclusions Chronic hyperglycemia, as assessed by A1C level, is associated with a significantly attenuated PTH responsiveness to vitamin D deficiency without a significant change in calcium level. On the other hand, there was no significant association between FPG and PTH level

Diversity, distribution and conservation of the terrestrial reptiles of Oman (Sauropsida, Squamata)

All authors: Salvador Carranza , Meritxell Xipell, Pedro Tarroso, Andrew Gardner, Edwin Nicholas Arnold, Michael D. Robinson, Marc Simó-Riudalbas, Raquel Vasconcelos, Philip de Pous, Fèlix Amat, Jiří Šmíd, Roberto Sindaco, Margarita Metallinou †, Johannes Els, Juan Manuel Pleguezuelos, Luis Machado, David Donaire, Gabriel Martínez, Joan Garcia-Porta, Tomáš Mazuch, Thomas Wilms, Jürgen Gebhart, Javier Aznar, Javier Gallego, Bernd-Michael Zwanzig, Daniel Fernández-Guiberteau, Theodore Papenfuss, Saleh Al Saadi, Ali Alghafri, Sultan Khalifa, Hamed Al Farqani, Salim Bait Bilal, Iman Sulaiman Alazri, Aziza Saud Al Adhoobi, Zeyana Salim Al Omairi, Mohammed Al Shariani, Ali Al Kiyumi, Thuraya Al Sariri, Ahmed Said Al Shukaili, Suleiman Nasser Al Akhzami.In the present work, we use an exceptional database including 5,359 records of 101 species of Oman’s terrestrial reptiles together with spatial tools to infer the spatial patterns of species richness and endemicity, to infer the habitat preference of each species and to better define conservation priorities, with especial focus on the effectiveness of the protected areas in preserving this unique arid fauna. Our results indicate that the sampling effort is not only remarkable from a taxonomic point of view, with multiple observations for most species, but also for the spatial coverage achieved. The observations are distributed almost continuously across the two-dimensional climatic space of Oman defined by the mean annual temperature and the total annual precipitation and across the Principal Component Analysis (PCA) of the multivariate climatic space and are well represented within 17 out of the 20 climatic clusters grouping 10% of the explained climatic variance defined by PC1 and PC2. Species richness is highest in the Hajar and Dhofar Mountains, two of the most biodiverse areas of the Arabian Peninsula, and endemic species richness is greatest in the Jebel Akhdar, the highest part of the Hajar Mountains. Oman’s 22 protected areas cover only 3.91% of the country, including within their limits 63.37% of terrestrial reptiles and 50% of all endemics. Our analyses show that large areas of the climatic space of Oman lie outside protected areas and that seven of the 20 climatic clusters are not protected at all. The results of the gap analysis indicate that most of the species are below the conservation target of 17% or even the less restrictive 12% of their total area within a protected area in order to be considered adequately protected. Therefore, an evaluation of the coverage of the current network of protected areas and the identification of priority protected areas for reptiles using reserve design algorithms are urgently needed. Our study also shows that more than half of the species are still pending of a definitive evaluation by the International Union for Conservation of Nature (IUCN).This work was funded by grants CGL2012-36970, CGL2015-70390-P from the Ministerio de Economía y Competitividad, Spain (cofunded by FEDER) to SC, the project Field study for the conservation of reptiles in Oman, Ministry of Environment and Climate Affairs, Oman (Ref: 22412027) to SC and grant 2014-SGR-1532 from the Secretaria d'Universitats i Recerca del Departament d'Economia i Coneixement de la Generalitat de Catalunya to SC. MSR is funded by a FPI grant from the Ministerio de Economía y Competitividad, Spain (BES-2013-064248); RV, PT and LM were funded by Fundação para a Ciência e Tecnologia (FCT) through post-doc grants (SFRH/BPD/79913/2011) to RV, (SFRH/BPD/93473/2013) to PT and PhD grant (SFRH/BD/89820/2012) to LM, financed by Programa Operacional Potencial Humano (POPH) – Quadro de Referência Estrategico Nacional (QREN) from the European Social Fund and Portuguese Ministerio da Educação e Ciência

Effects of hospital facilities on patient outcomes after cancer surgery: an international, prospective, observational study

Background Early death after cancer surgery is higher in low-income and middle-income countries (LMICs) compared with in high-income countries, yet the impact of facility characteristics on early postoperative outcomes is unknown. The aim of this study was to examine the association between hospital infrastructure, resource availability, and processes on early outcomes after cancer surgery worldwide.Methods A multimethods analysis was performed as part of the GlobalSurg 3 study-a multicentre, international, prospective cohort study of patients who had surgery for breast, colorectal, or gastric cancer. The primary outcomes were 30-day mortality and 30-day major complication rates. Potentially beneficial hospital facilities were identified by variable selection to select those associated with 30-day mortality. Adjusted outcomes were determined using generalised estimating equations to account for patient characteristics and country-income group, with population stratification by hospital.Findings Between April 1, 2018, and April 23, 2019, facility-level data were collected for 9685 patients across 238 hospitals in 66 countries (91 hospitals in 20 high-income countries; 57 hospitals in 19 upper-middle-income countries; and 90 hospitals in 27 low-income to lower-middle-income countries). The availability of five hospital facilities was inversely associated with mortality: ultrasound, CT scanner, critical care unit, opioid analgesia, and oncologist. After adjustment for case-mix and country income group, hospitals with three or fewer of these facilities (62 hospitals, 1294 patients) had higher mortality compared with those with four or five (adjusted odds ratio [OR] 3.85 [95% CI 2.58-5.75]; p<0.0001), with excess mortality predominantly explained by a limited capacity to rescue following the development of major complications (63.0% vs 82.7%; OR 0.35 [0.23-0.53]; p<0.0001). Across LMICs, improvements in hospital facilities would prevent one to three deaths for every 100 patients undergoing surgery for cancer.Interpretation Hospitals with higher levels of infrastructure and resources have better outcomes after cancer surgery, independent of country income. Without urgent strengthening of hospital infrastructure and resources, the reductions in cancer-associated mortality associated with improved access will not be realised

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Total and soluble fluoride concentration present in various commercial brands of children toothpastes available in Saudi Arabia – A pilot study

Objective: The aim of this pilot study was to perform chemical analysis and investigate the total and soluble fluoride concentrations in various brands of children toothpastes. Materials and methods: Three samples of five different commercial brands of children toothpastes were collected and divided into five groups; group A – Biorepair Oral Care toothpaste containing no fluoride (control), group B – Signal Kids Strawberry toothpaste having 500 ppm fluoride, group C – Aquafresh Milk Teeth toothpaste having 500 ppm fluoride, group D – Aquafresh Little Teeth toothpaste having 500 ppm fluoride, and group E – Siwak F Junior having 400 ppm F. The total fluoride (TF) and total soluble fluoride (TSF) concentration of the toothpastes was determined using fluoride ion selective electrode. Data were analysed using Paired sample t-test. Results: The measured TF values were inconsistent with that of the declared concentrations by the manufacturers. Mean TF found in the toothpastes ranged between 2.37 and 515.74 ppm whereas, the mean TSF ranged between 2.00 and 503.4 ppm. For two groups, TF was more than the declared TF whereas for the other three groups, it was less than the declared concentration. All the differences between the declared and observed TF concentration were statistically significant (p < .05) except for one group. All the toothpastes demonstrated mean TSF slightly lower than their respective observed mean TF concentrations. Conclusion: The analysis of TF and TSF concentrations revealed variations from the labelled claims. Therefore, some of the toothpastes may have doubtful anti-caries effectiveness owing to deficiency of total and soluble fluoride. Keywords: Fluoride, Fluoride ion electrode, Total fluoride, Total soluble fluoride, Toothpaste