Dust Effect on Solar Energy Systems and Mitigation Methods

Received: 2 February 2023. Accepted: 29 March 2023.Solar energy systems present a potential solution to global challenges in energy production and addressing environmental issues. However, such systems' performance could deteriorate in harsh weather conditions, which may lead to short- and long-term degradation. Particular attention should be paid to dust accumulation affecting both types of solar systems: Photovoltaic (PV) and Concentrated Solar Power systems (CSP). This review discusses the influencing factors affecting dust accumulation and the dust impact on solar systems. The comparison of dust accumulation effect on both technologies is then assessed. The reported dust accumulation studies showed more performance deterioration in CSP systems than in PV systems. In both cases, dust accumulation leads to a drop in optical characteristics resulting in a loss of energy yield. Potential mitigation methods and their advantages and disadvantages are also reviewed. It is concluded and recommended from the review analysis that dust accumulated on solar systems should be considered in the design and operation phases to define appropriate cleaning methods and frequencies.The authors would like to thank the University of Sharjah, Project #20020406150, for its financial support

Les traumatismes externes du larynx

Objective : Laryngeal injuries are rare. They can be isolated or associated with fractures of the facial skeleton. Early diagnosisand proper initial management may sometimes be difficult or delayed.The indication for surgery depends on the extent of the injury.Materials and methods : We report a retrospective review including thirty patients with laryngeal trauma treated over a 25-year periodResults : The mean age was 30 years. Commonest cause of injury was cut throat injuries followed by road traffic accidents. Fibreoptic endoscopy was performed for all the patients. Ct scan was done for 16 patients. All the patients were classified selon la classification de Schaeffer.More then the half (54%) was classified in stage I and II. Surgery was indicated for 16 patients. The treatment was conservative for all the cases. The middle recurrence was 2 years. Three of our patients developped a sous glottic stenosis. Two of them had a laryngoplasty type Rethi.Conclusion : Their symptoms are variable ranging from obvious airway obstruction to minor or almost missing symptoms. A coordinated team approach is necessary for proper management of these injuries.Keywords : Fibreoptic endoscopy, cervical CT-Scan, laryngeal stenosis, voice therapy session

Efficient Migration-Aware Algorithms for Elastic BPMaaS

International audienceAs for all kind of software, customers expect to find business process execution provided as a service (BPMaaS). They expect it to be provided at the best cost with guaranteed SLA. From the BPMaaS provider point of view it can be done thanks to the provision of an elastic cloud infrastructure. Providers still have to provide the service at the lowest possible cost while meeting customers expectation. We propose a customer-centric service model that link the BP execution requirement to cloud resources, and that optimize the deployment of customer’s (or tenants) processes in the cloud to adjust constantly the provision to the needs. However, migrations between cloud configurations can be costly in terms of quality of service and a provider should reduce the number of migrations. We propose a model for BPMaaS cost optimization that take into account a maximum number of migrations for each tenants. We designed a heuristic algorithm and experimented using various customer load configurations based on customer data, and on an actual estimation of the capacity of cloud resources

Modelling the potential effectiveness of hepatitis C screening and treatment strategies during pregnancy in Egypt and Ukraine

BACKGROUND & AIMS: Hepatitis C (HCV) test and treat campaigns currently excludes pregnant women. Pregnancy offers a unique opportunity for HCV screening and to potentially initiate direct-acting-antiviral treatment. We explored HCV screening and treatment strategies in two lower middle-income countries with high HCV prevalence, Egypt and Ukraine. METHODS: Country-specific probabilistic decision models were developed to simulate a cohort of pregnant women. We compared five strategies: S0, targeted risk-based screening and deferred treatment (DT) to after pregnancy/breastfeeding; S1, WHO risk-based screening and DT; S2, WHO risk-based screening and targeted treatment (treat women with risk factors for HCV vertical transmission (VT)); S3, universal screening and targeted treatment during pregnancy; S4, universal screening and treatment. Maternal and infant HCV outcomes were projected. RESULTS: S0 resulted in the highest proportion of women undiagnosed:59% and 20% in Egypt and Ukraine, respectively, with 0% maternal cure by delivery and VT estimated at 6.5% and 7.9%, respectively. WHO risk-based screening and DT (S1) increased the proportion of women diagnosed with no change in maternal cure or VT. Universal screening and treatment during pregnancy (S4) resulted in the highest proportion of women diagnosed and cured by delivery (65% and 70% respectively), and lower levels of VT (3.4% and 3.6% respectively). CONCLUSIONS: This is one of the first models to explore HCV screening and treatment strategies in pregnancy, which will be critical in informing future care and policy as more safety/efficacy data emerge. Universal screening and treatment in pregnancy could potentially improve both maternal and infant outcomes. IMPACT AND IMPLICATIONS: In the context of two lower middle-income countries with high HCV burden (Egypt and Ukraine), we designed a decision analytic model to explore five different HCV testing and treatment strategies for pregnant women, with the assumption that treatment was safe and efficacious for use in pregnancy. Assuming DAAs in pregnancy reduced vertical transmission, model findings indicate optimal maternal and infant benefits with provision of universal (rather than risk-based targeted) screening and treatment during pregnancy: the proportion of women diagnosed and cured by delivery would be 65% in Egypt and 70% in Ukraine (versus 0% with standard of care), and the proportion of infants that would be infected at the age of 6 months would decrease from 6.5% to 3.4% in Egypt, and from 7.9% to 3.6% in Ukraine, compared to standard of care. While future trials are needed to assess safety and efficacy of DAA treatment in pregnancy and impact on VT, there is increasing recognition that the elimination of HCV cannot leave entire subpopulations of pregnant women and young children behind. Our findings will be critical in informing policymakers in improving screening and treatment recommendations for pregnant women

Variability and associated uncertainty in image analysis for soiling characterization in solar energy systems

The accumulation of soiling on photovoltaic modules and on the mirrors of concentrating solar power systems causes non-negligible energy losses with economic consequences. These challenges can be mitigated, or even prevented, through appropriate actions if the magnitude of soiling is known. Particle counting analysis is a common procedure to characterize soiling, as it can be easily performed on micrographs of glass coupons or solar devices that have been exposed to the environment. Particle counting does not, however, yield invariant results across institutions. The particle size distribution analysis is affected by the operator of the image analysis software and the methodology utilized. The results of a round-robin study are presented in this work to explore and elucidate the uncertainty related to particle counting and its effect on the characterization of the soiling of glass surfaces used in solar energy conversion systems. An international group of soiling experts analysed the same 8 micrographs using the same open-source ImageJ software package. The variation in the particle analyses results were investigated to identify specimen characteristics with the lowest coefficient of variation (CV) and the least uncertainty among the various operators. The mean particle diameter showed the lowest CV among the investigated characteristics, whereas the number of particles exhibited the largest CV. Additional parameters, such as the fractional area coverage by particles and parameters related to the distribution's shape yielded intermediate CV values. These results can provide insights on the magnitude inter-lab variability and uncertainty for optical and microscope-based soiling monitoring and characterization

Assessment of aortic stiffness by cardiovascular magnetic resonance following the treatment of severe aortic stenosis by TAVI and surgical AVR

Aortic stiffness is increasingly used as an independent predictor of adverse cardiovascular outcomes. We sought to compare the impact of transcatheter aortic valve implantation (TAVI) and surgical aortic valve replacement (SAVR) upon aortic vascular function using cardiovascular magnetic resonance (CMR) measurements of aortic distensibility and pulse wave velocity (PWV).A 1.5 T CMR scan was performed pre-operatively and at 6 m post-intervention in 72 patients (32 TAVI, 40 SAVR; age 76 ± 8 years) with high-risk symptomatic severe aortic stenosis. Distensibility of the ascending and descending thoracic aorta and aortic pulse wave velocity were determined at both time points. TAVI and SAVR patients were comparable for gender, blood pressure and left ventricular ejection fraction. The TAVI group were older (81 ± 6.3 vs. 72.8 ± 7.0 years, p < 0.05) with a higher EuroSCORE II (5.7 ± 5.6 vs. 1.5 ± 1.0 %, p < 0.05). At 6 m, SAVR was associated with a significant decrease in distensibility of the ascending aorta (1.95 ± 1.15 vs. 1.57 ± 0.68 × 10(-3)mmHg(-1), p = 0.044) and of the descending thoracic aorta (3.05 ± 1.12 vs. 2.66 ± 1.00 × 10(-3)mmHg(-1), p = 0.018), with a significant increase in PWV (6.38 ± 4.47 vs. 11.01 ± 5.75 ms(-1), p = 0.001). Following TAVI, there was no change in distensibility of the ascending aorta (1.96 ± 1.51 vs. 1.72 ± 0.78 × 10(-3)mmHg(-1), p = 0.380), descending thoracic aorta (2.69 ± 1.79 vs. 2.21 ± 0.79 × 10(-3)mmHg(-1), p = 0.181) nor in PWV (8.69 ± 6.76 vs. 10.23 ± 7.88 ms(-1), p = 0.301) at 6 m.Treatment of symptomatic severe aortic stenosis by SAVR but not TAVI was associated with an increase in aortic stiffness at 6 months. Future work should focus on the prognostic implication of these findings to determine whether improved patient selection and outcomes can be achieved

Persistent left superior vena cava: Review of the literature, clinical implications, and relevance of alterations in thoracic central venous anatomy as pertaining to the general principles of central venous access device placement and venography in cancer patients

Persistent left superior vena cava (PLSVC) represents the most common congenital venous anomaly of the thoracic systemic venous return, occurring in 0.3% to 0.5% of individuals in the general population, and in up to 12% of individuals with other documented congential heart abnormalities. In this regard, there is very little in the literature that specifically addresses the potential importance of the incidental finding of PLSVC to surgeons, interventional radiologists, and other physicians actively involved in central venous access device placement in cancer patients. In the current review, we have attempted to comprehensively evaluate the available literature regarding PLSVC. Additionally, we have discussed the clinical implications and relevance of such congenital aberrancies, as well as of treatment-induced or disease-induced alterations in the anatomy of the thoracic central venous system, as they pertain to the general principles of successful placement of central venous access devices in cancer patients. Specifically regarding PLSVC, it is critical to recognize its presence during attempted central venous access device placement and to fully characterize the pattern of cardiac venous return (i.e., to the right atrium or to the left atrium) in any patient suspected of PLSVC prior to initiation of use of their central venous access device

Calcific aortic valve stenosis:hard disease in the heart: A biomolecular approach towards diagnosis and treatment

Calcific aortic valve stenosis (CAVS) is common in the ageing population and set to become an increasing economic and health burden. Once present, it inevitably progresses and has a poor prognosis in symptomatic patients. No medical therapies are proven to be effective in holding or reducing disease progression. Therefore, aortic valve replacement remains the only available treatment option. Improved knowledge of the mechanisms underlying disease progression has provided us with insights that CAVS is not a passive disease. Rather, CAVS is regulated by numerous mechanisms with a key role for calcification. Aortic valve calcification (AVC) is actively regulated involving cellular and humoral factors that may offer targets for diagnosis and intervention. The discovery that the vitamin K-dependent proteins are involved in the inhibition of AVC has boosted our mechanistic understanding of this process and has opened up novel avenues in disease exploration. This review discusses processes involved in CAVS progression, with an emphasis on recent insights into calcification, methods for imaging calcification activity, and potential therapeutic options