41 research outputs found
Non invasive assessment of liver fibrosis in chronic hemodialysis patients with viral hepatitis C
The liver biopsy has long been the "gold standard" for assessing liver fibrosis in patients with hepatitis C. It’s an invasive procedure which is associated with an elevated bleeding, especially in chronic hemodialysis patients. Main goal is to assess liver fibrosis in chronic hemodialysis with HCV by Fibroscan and by biological scores (APRI, Forns and Fib-4), and to measure the correlation between these tests. Cross-sectional study including all chronic hemodialysis patients with hepatitis C virus, in two public hemodialysis centers of Fez. All patients were evaluated for liver fibrosis using noninvasive methods (FibroScan and laboratory tests). Subsequently, the correlation between different tests has been measured. 95 chronic hemodialysis were studied, twenty nine patients (30.5%) with chronic hepatitis C. The average age was 52.38 ± 16.8 years. Nine liver fibrosis cases have been concluded by forns score. Fibroscan has objectified significant fibrosis in 6 cases. On the other side APRI has objectified sgnifivant fibrosis only in 3 cases. The Fib-4 showed severe fibrosis in five cases. The results have been most consistent between APRI and Fib-4, followed by Fibroscan and Forns, then APRI and FibroScan.Key words: APRI, fib4, fibroscan, forns, hepatitis C virus, liver fibrosis, chronic hemodialysis
Physical volcanology and emplacement mechanism of the Central Atlantic Magmatic Province (CAMP) lava flows from the Central High Atlas, Morocco
The best preserved and most complete lava flow sequences of the Central Atlantic Magmatic Province (CAMP) in Morocco are exposed in the Central High Atlas and can reach up to 300 m in thickness. Four distinct formations, emplaced in subaerial environments, are classically recognized: the Lower, Intermediate, Upper and Recurrent formations. These formations are separated by paleosoils and sedimentary sequences (mudstones, siltstones, sandstones, limestones), that are in general less than two meter-thick and may exceptionally reach a thickness of 80 m, representing minor periods of volcanic quiescence. CAMP lava flows of the Central High Atlas can be grouped into two main categories: subaerial compound pahoehoe flows and simple flows. The former type is exclusively confined to the Lower and Intermediate Formations, while simple flows occur in the Upper and Recurrent Formations. The dominance of compound flows in the two lowermost units of the CAMP suggests a slow emplacement during successive sustained eruptive episodes. Instead the thick single flows characterizing the Upper and Recurrent units indicate higher effusive rates. Basaltic pillow lavas (always of short lateral extent: 10 to 100 m), showing radial jointing and vitreous rinds, identical to those found in the Western Meseta, are occasionally associated with hyaloclastites in the base of the Intermediate
Formation, immediately above clastic sediments, or in the Upper Formation. The occurrence of pillow lavas does not imply a generalized subaqueous environment at the time of the lava emission. Instead, they represent subaerial flows that entered small lakes occupying depressions on the volcanic topography of the Lower and Intermediate Formations. The short lateral extent of the pillow lavas and their constant stratigraphic position, the existence of lava flows with unequivocal subaerial characteristics associated to sediments containing fossilized wood, clearly indicate onshore emplacement.info:eu-repo/semantics/publishedVersio
Physical volcanology and emplacement mechanism of the Central Atlantic Magmatic Province (CAMP) lava flows from the Central High Atlas, Morocco
Actas del III Seminario Hispano-MarroquĂ (Algeciras, abril de 2011)
Actas del III Seminario Hispano-MarroquĂ (Algeciras, abril de 2011
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
Data on effect of a reducer of water and retarder of setting time admixtures of cement pastes and mortar in hardened stat
The aim of this work is to study the influence of the admixture of superplasticizers on the physical properties of cement paste to know the initial and final time, water content and mechanical performance of concrete.In this work we have incorporated an Advanced Superplasticité for Prolonged Slump Retention (ASPPSR402) in the formulation matrix of concrete at different percentages ranging from 0.5% to 5% by weight of cement with a step of 0.5%, while partially substituting the mixing water by the last one to reduce the amount of water used.The obtained results by different prospected formulations show that the admixture of ASPPSR402 in formulations matrix significantly reduces the (Water/Cement “W/C”) ratio. Subsequently, we observed that the initial and final time increases in function of the percentage of ASPPSR402. Similarly, the compressive strength at the young age, median age and long-term has been improved. Keywords: Superplasticizers, Reducer of water, Durable concrete, Retarder of setting, Physical properties, High performance, Compressive strengt
Optimized piezoelectric sensor for a specific application : detection of Lamb waves
This work is devoted to the development and the optimization of a new piezoelectric sensor using Lamb waves destined to aerospace structures health monitoring. In such systems, Lamb waves are usually excited and received by thin single piezoelectric transducers. One of the most critical tasks in health monitoring is to identify all the generated Lamb waves in order to ease the damage estimation. A possible solution is to measure the Lamb wave signal at different locations along the propagation direction. So, the development of a distributed sensing technology using metallic multi-electrode deposited on a piezoelectric substrate was a key element, which built the bridge between the sensors signals and the structural integrity interpretation.Firstly, the various manufacture stages of this new sensor by the tape casting technique were reported. Secondly, piezoelectric properties of this sensor were measured by the electrical resonance technique. The sensitivity of this new sensor to the multi-wave generation and the damage detection were then further demonstrated in the case of an aluminum plate
Energy Consumption Prediction for Fused Deposition Modelling 3D Printing Using Machine Learning
Additive manufacturing (AM) technologies are growing more and more in the manufacturing industry; the increase in world energy consumption encourages the quantification and optimization of energy use in additive manufacturing processes. Orientation of the part to be printed is very important for reducing energy consumption. Our work focuses on defining the most appropriate direction for minimizing energy consumption. In this paper, twelve machine learning (ML) algorithms are applied to model energy consumption in the fused deposition modelling (FDM) process using a database of the FDM 3D printing of isovolumetric mechanical components. The adequate predicted model was selected using four performance criteria: mean absolute error (MAE), root mean squared error (RMSE), R-squared (R2), and explained variance score (EVS). It was clearly seen that the Gaussian process regressor (GPR) model estimates the energy consumption in FDM process with high accuracy: R2 > 99%, EVS > 99%, MAE < 3.89, and RMSE < 5.8
Energy Consumption Prediction for Fused Deposition Modelling 3D Printing Using Machine Learning
Additive manufacturing (AM) technologies are growing more and more in the manufacturing industry; the increase in world energy consumption encourages the quantification and optimization of energy use in additive manufacturing processes. Orientation of the part to be printed is very important for reducing energy consumption. Our work focuses on defining the most appropriate direction for minimizing energy consumption. In this paper, twelve machine learning (ML) algorithms are applied to model energy consumption in the fused deposition modelling (FDM) process using a database of the FDM 3D printing of isovolumetric mechanical components. The adequate predicted model was selected using four performance criteria: mean absolute error (MAE), root mean squared error (RMSE), R-squared (R2), and explained variance score (EVS). It was clearly seen that the Gaussian process regressor (GPR) model estimates the energy consumption in FDM process with high accuracy: R2 > 99%, EVS > 99%, MAE < 3.89, and RMSE < 5.8