Emergency Distance Education (EDE), Urgent Transition to Distance Learning from the Perspective of UAE University Teachers

To combat the spread of COVID-19, education systems around the world were facing an unprecedented challenge of mass university closures. This research attempts to analyze this sudden and urgent transition to Distance Learning, which was a new experience for 93.9% of UAE university teachers. We have called this urgent situation “Emergency Distance Education”, to which we have given a definition. A survey was conducted among 240 teachers to express their opinion on this new way of teaching, and to answer a set of questions, such as: what were their main challenges? did they provide theoretical courses in the same way as practical courses? and what do they suggest as future solutions for best practices in Distance Learning? As result, we found three categories of challenges raised by the respondents, namely: Pedagogical, Technical, and Interaction problems. The results of this study show that the greatest number of teachers were suddenly transferred to Distance Education without having previous experience. And the most notable suggestion made by more than 60% of teachers, and which could be an open path to a new field of study, is that the measure of a credit hour in Distance Education compared to that in face-to-face must be reviewed

An Evolutionary Approach for Learning Opponent's Deadline and Reserve Points in Multi-Issue Negotiation

The efficiency of automated multi-issue negotiation depends on the available information about the opponent. In a competitive negotiation environment, agents do not reveal their parameters to their opponents in order to avoid exploitation. Several researchers have argued that an agent's optimal strategy can be determined using the opponent's deadline and reserve points. In this paper, we propose a new learning agent, so-called Evolutionary Learning Agent (ELA), able to estimate its opponent's deadline and reserve points in bilateral multi-issue negotiation based on opponent's counter-offers (without any additional extra information). ELA reduces the learning problem to a system of non-linear equations and uses an evolutionary algorithm based on the elitism aspect to solve it. Experimental study shows that our learning agent outperforms others agents by improving its outcome in term of average and joint utility

One step protocol and green synthesis of 2-N,N-dimethylamino-3-alkyl(aryl)-2-oxido-1- hydro-2-benzo[1,3,2]diazaphosphinine-4-one derivatives

ABSTRACT. 2-N,N-dimethylamino-2-oxido-3-alkyl(aryl)-1-hydro-2-benzo[1,3,2]diazaphosphinin-4-one (2) derivatives  are synthesized by one pot reaction by reacting equimolar quantities of anthranilic acid, primary amine, and N,N-dimethylphosphoramic dichloride under reflux of ethanol with good yields. The structure of the compounds were established on the basis of their infrared, nuclear magnetic resonance spectral data (1H NMR, 13C NMR and 31P NMR), mass spectrometry, and elemental analysis.   KEY WORDS: Anthranilic acid, N,N-Dimethylphosphoramic dichloride, Diazaphosphinine Bull. Chem. Soc. Ethiop. 2022, 36(4), 859-864.                                                               DOI: https://dx.doi.org/10.4314/bcse.v36i4.11                                                   &nbsp

Estudio de la dinámica sedimentaria de la Laguna costera del Sur de Túnez (Túnez, Mar Mediterráneo)

The South lagoon of Tunis, a shallow Mediterranean lagoon, had undergone an important restoration management (during the period 1998-2001), leading to structural and functional changes of this coastal ecosystem. In this work, a comprehensive study of sedimentary dynamic based on hydrodynamic data, granulometric analysis, mineralogy and impact evaluation is presented. Restoration project, especially the establishment of two groups of inlets gates of the channel of Rades and Tunis (recalibrated during the restoration management), imposed an east-west water flow direction, created from high tide submersion, with an average flow exchanged with the sea about 80 m3s-1. This current control local sediment sorting. The grain sizes analysis of superficial sediment shows that the lagoon bottom characterized by fine sediments ( < 63 μm, 50-90%). The sediment dynamic is controlled by the lagoon water currents inducing an east-west grain-size sorting. The extreme eastern side of the lagoon, close to the inlet gate, is lined by medium sand, moderately sorted and transported by saltation. The central and western sides of the lagoon are covered by fine sand, poorly sorted, and deposed in relatively calm hydrodynamic conditions. Mineralogical results reveal the following association: quartz (13 to 69%), biogenic calcite, (15 to 81%), aragonite (0 to 8%), pyrite (0 to 1,75%) and accessory magnetite, smectite, illite and kaolinite. The lagoon seems to be a protected zone as a result of restoration project that forms a physical barrier for sedimentary materials amount from Gulf of Tunis.La laguna sur de Túnez, una laguna costera mediterránea poco profunda, se sometió a importantes trabajos de restauración durante el período 1998-2001, lo que ha llevado a cambios estructurales y funcionales de este ecosistema costero. En este trabajo se presenta un estudio integral de dinámica sedimentaria basado en datos hidrodinámicos, análisis granulométrico, mineralogía y evaluación de impacto. El proyecto de restauración, especialmente el establecimiento de la puerta de entrada de los canales de Rades y Túnez, impuso una dirección de flujo de agua este-oeste controlando la clasificación local de sedimentos. El análisis de tamaño de grano del sedimento superficial muestra que el fondo de la laguna está revestido por sedimentos finos

L'inhibition de l'entartrage par les eaux géothermales du sud tunisien. Étude sur site

Une nappe d'eaux fossiles à grande profondeur (800 à 2 700 mètres) a été mise en exploitation dans le Sud-Tunisien pour alimenter une usine d'osmose inverse située à Gabès ayant une production de 15 000 m3 /jour, afin de lutter contre la désertification par irrigation et d'assurer le chauffage de serres pour la production de primeurs. La grande dureté (TH de l'ordre de 100 à 140 °F) de ces eaux géothermales a pour conséquence le colmatage rapide des conduites de distribution : 40 à 50 tonnes de tartre par forage, constitué essentiellement de carbonate de calcium, précipitent chaque année. Ce tartre est constitué d'aragonite comme le montrent la microscopie électronique à balayage et la diffraction des rayons X. Une technique électrochimique, la chronoélectrogravimétrie, permet d'étudier l'inhibition de l'entartrage par des composés de la famille des phosphates inorganiques, des phosphonates organiques et des polycarboxylates. La concentration efficace de chacun de ces inhibiteurs agissant par effet de seuil a été déterminée : elle est de l'ordre de 1,1 à 1,5 mg.l-1 pour l'eau du forage de EL HAMMA. Un essai sur le site de EL MANSOURA a été effectué en privilégiant un inhibiteur produit industriellement dans le Sud-Tunisien, le triphosphate de sodium. A la concentration de 1 mg.l-1 il évite l'entartrage du système de refroidissement de type cascade - piscines et des conduites de distribution.Deep fossil waters are used in Southern Tunisia (Gabès, Kébili, Tozeur) for the Gabès reverse osmosis plant, which delivers a flow rate of 15 000 m3 /day for irrigation and for heating greenhouses used for the production of early fruits and vegetables. Drilling depths vary between 800 and 2 700 meters. Water emerges under a pressure of ca. 20 bars and has a temperature between 50 and 73 °C. Mean flow rate is 7 800 m3 /day.Intake water at the Gabès plant has a salinity of 3.3 g.l-1 ; after reverse osmosis the salinity is less than 0.1 g.l-1. Water used for irrigation has to be cooled. Geothermal waters are characterized by high concentrations of calcium, magnesium, sulphate and chloride. Bicarbonate anions are present at limited concentrations (approx. 2.10-3 mol.l-1) that are, however, sufficient for the formation of large quantities of scale - 40 to 50 tons per year for each drilling. At the outlet of the drill hole, pressure decreases strongly, liberating carbon dioxide to the atmosphere. Water pH increases and the following equilibrium is displaced to the right, with scale precipitation : Ca2+ + 2HCO3-CO2 (g) + CaCO3(s) + H2OScale precipitation has two consequences :- the plugging of distribution pipes: a 85% reduction of the pipe has been observed, after four years, for an initial diameter of 15 cm; - water cooling installations such as cooling towers or pool systems are blocked by large quantities of scale, which have to be removed regularly. Scales have been analysed through inductively coupled plasma spectroscopy and thermogravimetry: calcium carbonate may represent, depending on the origin of the drilling water, 60 to 95% by weight of the solid. Iron oxides, silica, calcium phosphate and aluminum are present. Scanning electron microscopy and X-ray diffraction show that calcium carbonate precipitates in the form of aragonite. This is due to two reasons: the temperature at the drilling outlet is greater than 60 °C and the high magnesium concentration favours aragonite formation. Scale inhibition is possible through the use of certain chemicals such as phosphates, organic phosphonates and polycarboxylates.Chronoelectrogravimetry was used as the experimental method to determine the inhibitor concentration able to suppress scale precipitation. Dissolved oxygen is electrochemically reduced on a gold electrode; hydroxide anions are produced in the vicinity of the electrode and calcium carbonate precipitates according to:4Ca2+ + 4HCO3- + O2 + 4e -> 4CaCO3(s) + 2H2OThe gold electrode is deposited on the quartz disk of a recording microbalance. The electrode is polarized at - 1 V/SCE with a three-electrode potentiostatic device and the weight of CaCO3 deposited is recorded versus time.Four inhibitors have been studied :- PERMATREAT 191, which is the sodium salt of aminotris(methylenephosphonic) acid N(CH2COONa)3; - a proprietary organic phosphonate with high resistance to chlorine oxidation (DEQUEST 6004) ; - phosphonobutanetricarboxylic acid (DEQUEST 7000, BAYHIBIT-AM) ; - a copolymer of acrylic acid and acrylamidopropanesulfonic acid (FERROPHOS 5248). Breakthrough effects are obtained in the case of EL HAMMA water for the following concentrations: PERMATREAT 191: 1.1 mg.l-1 ; DEQUEST 6004: 1.5 mg.l-1 ; DEQUEST 7000: 1.3 mg.l-1 ; FERROPHOS 5248: 1.4 mg.l-1. These concentrations are low and, as a consequence, these inhibitors can be used for antiscale action even with high water flow rates.A field experiment was carried out on the EL MANSOURA drilling where water is cooled in three pools (input water: 5 184 m3 /day, temperature: 60 °C). For economical reasons the chosen inhibitor was sodium triphosphate Na5 P3 O10, which is produced industrially in Southern Tunisia. By chronoelectrogravimetry it has been shown that, with EL MANSOURA water, a breakthrough effect is obtained with a sodium triphosphate concentration of 0.75 mg.l-1.A dosing pump was used to inject sodium triphosphate in such a way that the inhibitor concentration would be 1 mg.l-1 in one of three pools, the two others not being treated. After four months a scale deposit of 23 cm was obtained in the untreated pools and the pipe diameter was reduced by 39%. In the treated pool scale deposit was not observed and the pipe diameter remained unchanged. In the untreated basins, examination of scale with electron scanning microscopy revealed that it was aragonite; in the treated basin, the precipitate was amorphous and an X-ray diffraction pattern with no characteristic bands was obtained.Some algal development was observed in the pool due to phosphate addition but this development was not a nuisance after the four month period. However, it could be suppressed by the use of an organic phosphonate or polycarboxylate as scale inhibitor

Update of alien fauna and new records from Tunisian marine waters

An updated inventory of alien marine fauna in coastal and offshore Tunisian waters is presented. Records were compiled from scientific and ‘grey’ publications, presentations at scientific meetings, theses presented in fulfillment of requirements towards MSc and PhD degrees, websites and personal observations. 136 alien species were recorded in Tunisian waters, 60 records in northern coasts, West Mediterranean and 76 in central and southern coasts, Central Mediterranean. Nearly half of the first sightings in Tunisian waters took place in the Gulf of Gabès. The dominant taxa are Crustancean (24%), Molluscs (23%), Fishes (19%) and Annelida (13%). Twenty one species previously reported as aliens, were upon consideration, reclassified as range-expanding Atlantic species. Amathia verticillata, previously considered native to the Mediterranean, is reclassified as pseudoindigenous. Twenty one alien species are newly recorded from Tunisia, including 5 fish species, 5 polychaetes, 4 crustaceans, 4 molluscs, and one each schyphozoan, bryozoan and tunicate. The findings of Gibberulus gibberulus albus, Morula aspera and Calcinus latens, three species new to the Mediterranean, and of Actaedoes tomentosus, reported for the second time in the basin, are described. Species were classified according to their establishment status and their origins. This contribution highlights the dual origin of biological invasion in Tunisian waters (Red Sea and Atlantic), with slightly more species of Red Sea and Indo-Pacific origin (61,76%).  The impact of the alien species in Tunisian waters was discussed

Performance of the BD-FACS Presto for CD4 count and hemoglobin measurement in a district hospital and rural laboratory in Ghana

Introduction In Ghana, initiation of Antiretroviral Therapy (ART) is recommended for all patients with an HIV diagnosis, regardless of CD4+ T-cell count. However, measurement of CD4 count remains an important metric for identifying patients with advanced HIV disease, and assessing a person’s overall immune status, which informs the decision to offer opportunistic infection screening and prophylaxis. Access to CD4+ T cell count in rural health facilities remains a major challenge in Ghana and other resource-limited settings. This study aimed to validate the accuracy of the BD FACSPresto near-patient device for measurement of CD4 count and hemoglobin concentration against the FACSCount (CD4) and Sysmex (hemoglobin) diagnostic machines when operated in both a district hospital and rural laboratory, serving a network of health posts in Ashanti Region, Ghana. Methodology In the first phase of the study, patients were recruited from a district hospital, and both venous and capillary blood samples were tested using the FACSCount and Sysmex as reference tests and compared to results of the FACSPresto performed in the clinic laboratory at the district hospital. In the second phase, patients were recruited from both the hospital and from rural health clinics, and samples were tested using the FACSPresto at a rural laboratory. Sensitivity and specificity among samples categorized into different clinically relevant CD4 count ranges were calculated, along with correlation between the Presto and the reference measurements, and mean and relative bias with limits of agreement. Results The FACSPresto was successfully operated in both clinical settings. A total of 59 samples in the first phase and 48 samples in the second phase were included. Positive bias was observed when comparing CD4 count measured by BD FACSPresto to FACSCount in the district hospital (bias = 44, LOA -72,160) and in the rural laboratory setting (bias = 74, LOA -96, 244). In addition, capillary blood samples were shown to give higher measures when compared to venous blood samples from the same participant. All results were statistically significant (p<0.05) apart from hemoglobin measurement in venous blood in the rural laboratory. Correlation coefficients were high for CD4 count measures and lower for hemoglobin measures. Conclusion Overall, the Presto gave higher estimates of CD4 count compared to FACSCount, and hemoglobin measurements were higher than from Sysmex. Samples of capillary blood in turn gave higher results for both measurements compared to venous blood, consistent with previous analyses. These findings should be considered when selecting CD4 count machines for use at the point of care, especially in remote areas where capillary blood sampling may be preferable, but are likely balanced by device’s ease of use, portability, and ability to expand access to services. These results are some of the first to demonstrate the accuracy of the FACSPresto in West Africa and show that this device can be successfully operated in a very rural lab setting and may therefore assist to provide CD4 count and hemoglobin concentration measurement to populations in need

Les goitres plongeants : particularites cliniques, radiologiques et therapeutiques

Introduction: Les goitres plongeants, devenus rares de nos jours, posent des problèmes diagnostiques et chirurgicaux particuliers. Leur prise en charge est facilitée par l’apport de la tomodensitometrie permettant de planifier l’attitude thérapeutique.Le but de ce travail est de préciser les modalités d’exploration et de prise en charge chirurgicale des goitres plongeants.Matériels et méthodes : Nous rapportons une étude rétrospective portant sur42 cas de goitre plongeant colligés sur une période de 11 ans entre 2001 et 2011.Résultats : L’âge moyen de nos patients était de 56,9 ans (36-86 ans). Le sex-ratio était de 0,13. La tuméfaction basi-cervicale était le motif de consultation le plus fréquent, rapportée dans 74 % des cas associée à des signes de compression oesotrachéale dans 45% des cas.Une paralysie récurrentielle unilatérale a été objectivée dans 3 cas.Une radiographie de thorax a montré un élargissement médiastinal dans 23% des cas avec déviation trachéale chez63 % des malades. Une TDM cervico-thoracique pratiquée dans 85% des cas a confirmé le diagnostic. Le traitement chirurgical était mené par voie cervicale exclusive chez tous les patients. Une paralysie récurentielle a été observée dans 3 cas. Aucune hypoparathyroïdie définitive n’a été rapportée avec un reculmoyen de 24mois.Conclusion : Les goitres plongeants devenus rares du fait de la prise en charge plus précoce des nodules thyroïdiens. Ils posent actuellement moins de difficultés thérapeutiques. L’indication chirurgicale est toujours formelle devant le risque vital qu’ils posent.Mots clés : goitre cervicothoracique, thyroïdectomie, paralysie récurrentielle, hypoparathyroïdie.Introduction: Substernal goiters, becoming rare, present diagnositic and therapeutic problems.Their management is facilitated by the contribution of computed tomography for planning the therapeutic approach. The aim of this study is to specify the procedures for exploration and surgical management of substernal goiters.Materials and Methods: We report a retrospective study of 42 cases of substernalgoiters collaged over a period of 11 years between 2001 and 2011.Results: The mean age was 56,9 years (36- 86 years). The sex ratio was 0,13. Cervical swelling was the most common reason for consultation, reported in 74% of cases associated with signs of oesotrachealcompression in 45% of cases. Unilateral laryngeal palsy has been objectified in 3 cases. Chest-x-Ray showed widening of mediastinal shadowwith tracheal deviation in 63% of patients. A cervico-thoracic CT performed in 85% of cases confirmed the diagnosis of substernal goiters. The cervical approach has been used in all cases. Laryngeal nerve palsy was observed in 3 cases. No definitive hypoparathyroidism have been reported with a mean of 24 months.Conclusion: Substernal goiters become rare due to the earlier diagnosis of thyroid nodules. They currently present fewer therapeutic difficulties, and must be managed surgically because of vital risk.Key words: substernal goiter, thyroidectomy, laryngeal nerve palsy, hypoparathoidism

The absolutely continuous spectrum of one-dimensional Schr"odinger operators

This paper deals with general structural properties of one-dimensional Schr"odinger operators with some absolutely continuous spectrum. The basic result says that the omega limit points of the potential under the shift map are reflectionless on the support of the absolutely continuous part of the spectral measure. This implies an Oracle Theorem for such potentials and Denisov-Rakhmanov type theorems. In the discrete case, for Jacobi operators, these issues were discussed in my recent paper [19]. The treatment of the continuous case in the present paper depends on the same basic ideas.Comment: references added; a few very minor change