Internal transcribed spacer sequences analysis of genetic variation among and within populations of Atriplex halimus from different bioclimatic zones in Morocco

The genetic diversity of 12 Atriplex halimus L. populations collected throughout its natural range in Morocco has been studied by using sequences of nrDNA ITS region. Within-population genetic diversity was high in comparison to others species with similar life histories and ecological traits. Most of genetic variation detected by AMOVA resided within populations (94%), relative to the amount of variation among populations (6%). The level of populations differentiation (FST = 0.06) was low, which corresponds with the high level of gene flow (4.00) revealed between populations. Differentiation among ecological groups of populations accounted only for 1.23% of the total ITS variation, which indicates that climatic conditions did not have an effect of population's structuration or that this differentiation is obviously not related to ITS markers. Furthermore, very low genetic differentiation (FCT = 0.015) was observed between regions (Moroccan populations versus American population). Strangely enough, geographic distances were not correlated to genetic differentiation between the populations (r = 0.06, P = 0.5). The structuration of populations in five groups was not operated according to their bioclimatic type. The data obtained in this assay could play a crucial role to establish efficient strategies for genetic resources conservation and to work out the scheme of breeding programs of Atriplex

Performance Comparison of Phase Shifted PWM and Sorting Method for Modular Multilevel Converters

Modular Multilevel Converters (MMC) are the solution of preference in HVDC applications due to modularity, scalability, low losses and low filtering requirement. Carrier-based (PWM) and carrier-less (nearest level control) modulation can be applied. By using advanced sorting methods focusing on keeping the capacitor voltage ripple under some limit, unnecessary switching events are eliminated leading to reduced switching losses. This paper presents a comparison between the steady-state performances in terms of output voltage THD and equivalent switching frequency of the Phase Shifted Carrier PWM and NLC plus sorting methods

Valutazione anatomica della mandibola anteriore in chirurgia orale

The purpose of this article was to evaluate incidence, size, location, course and content of bony foramina and canals located on the lingual side of mandibular midline. Examination of dissections clearly showed a neurovascular bundle in both superior and inferior genial foramina and canals. This means that surgery and especially implant placement in mandibular midline may endanger both blood vessels and nerves. Besides that, several arteries running tbrough these foramina are wide enough to cause severe bleeding in the floor of the oral cavity if they are damaged

The genetic structure of Arabidopsis thaliana in the south-western Mediterranean range reveals a shared history between North Africa and southern Europe

Background Deciphering the genetic structure of Arabidopsis thaliana diversity across its geographic range provides the bases for elucidating the demographic history of this model plant. Despite the unique A. thaliana genomic resources currently available, its history in North Africa, the extreme southern limit in the biodiversity hotspot of the Mediterranean Basin, remains virtually unknown. Results To approach A. thaliana evolutionary history in North Africa, we have analysed the genetic diversity and structure of 151 individuals collected from 20 populations distributed across Morocco. Genotyping of 249 genome-wide SNPs indicated that Morocco contains substantially lower diversity than most analyzed world regions. However, IBD, STRUCTURE and PCA clustering analyses showed that genetic variation is strongly geographically structured. We also determined the genetic relationships between Morocco and the closest European region, the Iberian Peninsula, by analyses of 201 populations from both regions genotyped with the same SNPs. These analyses detected four genetic groups, but all Moroccan accessions belonged to a common Iberian/Moroccan cluster that appeared highly differentiated from the remaining groups. Thus, we identified a genetic lineage with an isolated demographic history in the south-western Mediterranean region. The existence of this lineage was further supported by the study of several flowering genes and traits, which also found Moroccan accessions similar to the same Iberian group. Nevertheless, genetic diversity for neutral SNPs and flowering genes was higher in Moroccan than in Iberian populations of this lineage. Furthermore, we analyzed the genetic relationships between Morocco and other world regions by joint analyses of a worldwide collection of 337 accessions, which detected an additional weak relationship between North Africa and Asia. Conclusions The patterns of genetic diversity and structure of A. thaliana in Morocco show that North Africa is part of the species native range and support the occurrence of a glacial refugium in the Atlas Mountains. In addition, the identification of a genetic lineage specific of Morocco and the Iberian Peninsula indicates that the Strait of Gibraltar has been an A. thaliana migration route between Europe and Africa. Finally, the genetic relationship between Morocco and Asia suggests another migration route connecting north-western Africa and Asia

Circulating Current Suppression Strategies for D-STATCOM Based on Modular Multilevel Converters

This work focuses on the circulating current control of a STAtic synchronous COMpensator (STATCOM) based on Modular Multilevel Converter (MMC). Two circulating current estimation strategies are analyzed, with focus on the converter performance improvement. The conventional method to estimated the circulating current has been improved using a Second Order Generalized Integrator (SOGI) structure. The proposed strategy eliminates the third harmonie component from the circulating current through a SOGI filter. Simulated and experimental results compare both classical and proposed strategy in terms of reduction in the circulating current, dynamic behavior during reference changes and reduction in the STATCOM losses

Circulating Current Suppression Strategies for D-STATCOM Based on Modular Multilevel Converters

This work focuses on the circulating current measurement of a STAtic synchronous COMpensator (STATCOM) based on Modular Multilevel Converter (MMC). In a Delta (D) connected MMC-based STATCOM configuration the currents are divided in two parts: grid currents and circulating currents. The latest circulates between legs and has no direct impact on the output current, but it has a third harmonic component, which causes problems in the circulating current control. Thus, this work evaluates three circulating current measurement strategies, with focus on the converter characteristics improvement, such as losses reduction. A classical strategy is compared with other two strategies using a Second Order Generalized Integrator (SOGI) structure. The first proposed strategy eliminates the third harmonic from the circulating current and the second detects the fundamental component of the circulating current eliminating the other harmonic components. Simulated and experimental results show that this strategies achieve reduction in the circulating current, and consequently reduction in the STATCOM losses