Control of the power quality for a DFIG powered by multilevel inverters

This paper treats the modeling, and the control of a wind power system based on a doubly fed induction generator DFIG, the stator is directly connected to the grid, while the rotor is powered by multilevel inverters. In order to get a decoupled system of controlfor an independently transits of active and reactive power, a vector control method based on stator flux orientation SFOC is considered: Direct vector control based on PI controllers. Cascaded H-bridge CHBI multilevel inverters are used in the rotor circuit to study its effect on supply power quality. All simulation models are built in MATLAB/Simulink software. Results and waveforms clearly show the effectiveness of vector control strategy. Finally, performances of the system will tested and compared for each levels of inverter

The relationship between organisational culture and knowledge sharing in the information communication technology firms in Libya

Examining the nature of the relationship between Organisational Culture (OC) and Knowledge Sharing (KS) has been the concern of a number of academic studies. Most of these studies have suggested that different aspects of Organisational Culture have an influence on the effective process of Knowledge Sharing in business firms. However, there has been a lack of studies carried out to examine the relationship between OC and KS in Information Communication Technology firms generally and in Arabic countries (namely Libya) in particular. Furthermore, there is a dearth of frameworks that assist employees in ICT firms to achieve better practices within KS processes.This study is driven by the need to bridge the gap in the current literature in terms of identifying the nature of the relationship between Organisational Culture and Knowledge Sharing in ICT firms in Libya. As the Information Communication Technology sector in Libya is now heading towards leading the country to a knowledge economy, there is also a need to put forward a framework that helps employees in ICT firms to achieve better practices. This study is undertaken with the aim to “investigate the relationship between Organisational Culture and Knowledge Sharing processes in ICT firms in Libya to enhance Knowledge Sharing practices”. The outcomes from this study are used to develop a framework that will help employees in ICT firms to achieve better practices.This study utilises a mixed research approach. The aim of the study was achieved by adopting the case study research strategy by triangulating the data collected through different techniques (questionnaire, semi-structured interviews and document analysis). Data was collected from four different ICT firms in Libya focusing on the relationship between Organisational Culture and Knowledge Sharing. Descriptive statistics, thematic analysis and content analysis methods were used to analysis the data.The findings from this research suggest that Organisational Culture and Knowledge Sharing are defined, interpreted, and understood differently, so that there is no one specific meaning for either KS or OC. Therefore, there is a need to understand the different meanings and the aspects associated with each concept in order to understand the relationship between both concepts. Furthermore, this study found that OC is influenced by the culture including personal, government, sector, and nation. At the same time, KS is influenced by OC and an organisation’s KS culture rather than by KS as practices or activities. According to the findings of this study, KS in ICT firms in Libya has not been practiced as a way of fulfilling either strategic or organisational practice, rather it has been practiced randomly. In other words, knowledge sharing plans are not formalised within the organisational strategic policies and practices. Therefore, a STEP BY STEP FRAMWORK has been developed with the intention to enhance the practices of KS in ICT firms in Libya which appear to be more retail-customer services’ businesses rather than ICT production service organisations. This fact could suggest that the framework can be applied in other different business contexts, but further investigations would be necessary. The findings of this study have contributed significantly by formulating a framework to enhance KS practices for the ICT firms in developing country as the usage of such framework are limited in countries like Libya

The 6th international conference on envenomation by snakebites and scorpion stings in Africa : a crucial step for the management of envenomation

During the 6th International Conference on Envenomation by Snakebites and Scorpion Stings in Africa held in Abidjan, from 1 to 5 June 2015, the measures for the management of envenomation were discussed and new recommendations were adopted by the participants. The high incidence and severity of this affliction were confirmed by several studies conducted in African countries. The poor availability of antivenom, particularly because of the cost, was also highlighted. Some experiences have been reported, mainly those regarding the financial support of antivenom in Burkina Faso (more than 90 %) and Togo (up to 60 %) or the mandatory reporting of cases in Cameroon. Key recommendations concerned: improvement of epidemiological information based on case collection; training of health workers in the management of envenomation; policy to promote the use of effective and safe antivenom; and antivenom funding by sharing its costs with stakeholders in order to improve antivenom accessibility for low-income patients

Motor phenotype of decline in cognitive performance among community-dwellers without dementia: Population-based study and meta-analysis

Background: Decline in cognitive performance is associated with gait deterioration. Our objectives were: 1) to determine, from an original study in older community-dwellers without diagnosis of dementia, which gait parameters, among slower gait speed, higher stride time variability (STV) and Timed Up & Go test (TUG) delta time, were most strongly associated with lower performance in two cognitive domains (i.e., episodic memory and executive function); and 2) to quantitatively synthesize, with a systematic review and meta-analysis, the association between gait performance and cognitive decline (i.e., mild cognitive impairment (MCI) and dementia). Methods: Based on a cross-sectional design, 934 older community-dwellers without dementia (mean6standard deviation, 70.3 64.9years; 52.1% female) were recruited. A score at 5 on the Short Mini-Mental State Examination defined low episodic memory performance. Low executive performance was defined by clock-drawing test errors. STV and gait speed were measured using GAITRite system. TUG delta time was calculated as the difference between the times needed to perform and to imagine the TUG. Then, a systematic Medline search was conducted in November 2013 using the Medical Subject Heading terms "Delirium," "Dementia," "Amnestic," "Cognitive disorders" combined with "Gait" OR "Gait disorders, Neurologic" and "Variability." Findings: A total of 294 (31.5%) participants presented decline in cognitive performance. Higher STV, higher TUG delta time, and slower gait speed were associated with decline in episodic memory and executive performances (all P-values <0.001). The highest magnitude of association was found for higher STV (effect size = -0.74 [95% Confidence Interval (CI): -1.05;- 0.43], among participants combining of decline in episodic memory and in executive performances). Meta-analysis underscored that higher STV represented a gait biomarker in patients with MCI (effect size = 0.48 [95% CI: 0.30;0.65]) and dementia (effect size = 1.06 [95% CI: 0.40;1.72]). Conclusion: Higher STV appears to be a motor phenotype of cognitive decline. © 2014 Beauchet et al

Vitamin D insufficiency and mild cognitive impairment: cross-sectional association

BACKGROUND: Low serum 25-hydroxyvitamin D (25OHD) concentrations have been associated with dementia. The association with mild cognitive impairment (MCI) has not yet been explored. Our aim was to examine the association between vitamin D status and MCI status amongst older community-dwellers with subjective memory complaint.METHODS: Ninety-five non-demented Caucasian community-dwellers with subjective memory complaint (mean, 71.16.4years; 54.7% women) included in the Gait and Alzheimer Interaction Tracking (GAIT) study were categorized into two groups according to Winblad et al. consensus criteria [i.e., subjects with MCI or cognitively healthy individuals (CHI)]. Serum 25OHD concentration was divided into quartiles, the fourth quartile corresponding to the highest 25OHD concentration. The cross-sectional associations between 25OHD concentrations and MCI were modeled using logistic regressions. Age, gender, body mass index, number of comorbidities, education level, Mini-Mental State Examination score, Frontal Assessment Battery score, Geriatric Depression Scale score, creatinine clearance, and season tested were considered as potential confounders. RESULTS: Compared to CHI, patients with MCI (n=43; mean, 71.45.6years; 34.9% women) had lower mean serum 25OHD concentrations (P=0.006) and belonged more often to the lower quartiles compared to the highest quartile (P=0.03). Increased serum 25OHD concentration was associated with a lower risk of MCI [adjusted odds ratio (OR)=0.96, P=0.002]. Accordingly, lower quartiles of 25OHD were positively associated with MCI whilst using the highest quartile as reference (adjusted OR=25.46, P=0.002 for the first quartile; adjusted OR=6.89, P=0.03 for the second quartile; and adjusted OR=10.29, P=0.02 for the third quartile). CONCLUSIONS: Low 25OHD concentrations were associated with MCI status in older non-demented community-dwellers with subjective memory complaint

COMPLICATIONS RETINIENNES DES ANTIPALUDEENS DE SYNTHESE. A PROPOS DE 2 CAS

Treatment with the antimalarials chloroquine or hydroxychloroquine is frequently used in dermatology and rheumatology. However irreversible retinal damage can occurs, that’s why intensive monitoring is still required. We report 2 cases of females patients aged of 33 and 42 years old, treated by antimalarials for polyarthritis and sclerodermia. After 4 years of treatment without ophthalmologic examination, they complain of decreased vision. The fundoscopic exam found a bilateral bull's eye appearence confirmed by fluorescein angiography. Even after cessation of treatment the visual acuity didn’t increase.Ocular toxicity of antimalarials treatment is rare but it can occurs. The retinopathy is the major concern. We found three stages: asymptomatic, obvious maculopathy and advanced retinopathy. Appropriate examinations (color vision, automatic visual field and electroretinogram) should be performed regularly. The frequency of screening should be based on patients’ classification.Les antipaludéens de synthèse sont largement utilisés en rhumatologie et en dermatologie pour leur action anti-inflammatoire. Ils exposent toute fois à des complications rétiniennes irréversibles d’où la nécessité d’une surveillance ophtalmologique régulière. Nous rapportons l’observation de deux patientes âgées de 33 et 42 ans, mises sous antipaludéens de synthèse respectivement pour une polyarthrite rhumatoïde et une sclérodermie. Elles ont poursuivies leur traitement pendant 3 à 4 ans sans surveillance ophtalmologique avant de consulter pour une baisse importante de l’acuité visuelle. L’examen ophtalmologique a retrouvé une acuité visuelle inférieure à 2/10ème dans le premier cas et une acuité visuelle inférieure à 6/10ème dans le deuxième cas ; avec au fond d’oeil un aspect de maculopathie bilatérale en oeil de boeuf typique confirmée par l’angiographie rétinienne à la fluoresceine. Malgré l’arrêt des antipaludéens de synthèse, l’acuité visuelle est restée stationnaire dans les deux cas. L’intoxication clinique aux antipaludéens de synthèse est rare mais possible. Elle prédomine dans la région maculaire et évolue en 3 stades: asymptomatique, maculopathie confirmée et stade de rétinopathie évoluée. Un bilan ophtalmologique initial doit être fait systématiquement, avant le début du traitement avec réalisation d’examens paracliniques (vision des couleurs, champs visuel automatisé, électrorétinographie maculaire). Au terme des ces examens les patients seront classés en trois groupes permettant ainsi de déterminer leur rythme de surveillance

LES UVEITES DE L’ENFANT : A PROPOS DE 30 CAS

Uveitis is less frequent in children. The purpose of our study is to evaluate epidemiologic aspect, etiological profile and prognosis of children uveitis.We report 30 cases of uveitis in patients aged less than 16 years old followed in our department.Patients mean age is 9 years old (5 to 16 years) .We observed anterior uveitis in 46,7%, posterior uveitis in 26,7%, intermediate uveitis in 13,3% and panuveitis in 13,3%.Chronic juvenile arthritis is the main etiology followed by Behcet disease.Uveitis in children is rare but severe and can involve visual prognosis; it needs urgent diagnosis and adapted treatment. Principals etiologies are; idiopathic juvenile arthritis and spondiloarthropaties. Functional prognosis is variable and final visual acuity is less than 20/200 in 16 to 36% of cases.L’uvéite de l’enfant est rare. Le but de notre travail est d’évaluer le profil épidémiologique, étiologique et pronostic des uvéites de l’enfant.Nous rapportons 30 cas d’uvéites chez des patients d’âge inférieur à 16 ans et suivis dans notre unité.La moyenne d’âge des patients est de 9 ans (5 à 16 ans). Il s’agissait d’une uvéite antérieure dans 46,7% des cas, d’une uvéite postérieure dans 26,7%, d’une uvéite intermédiaire dans 13,3% et d’une panuvéite dans 13,3%. Les principales causes retrouvées sont l’arthrite juvénile idiopathique suivie par la maladie de Behçet.L’uvéite de l’enfant est rare souvent grave engageant le pronostic visuel et imposant un diagnostic précoce et un traitement adapté. Les principales étiologies sont l’arthrite juvénile idiopathique et les spondyloarthropathies. Le pronostic visuel est variable et l’acuité visuelle est inférieure à 20/200 dans 16 à 36% des cas