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Despite significant research dedicated to the marine genus Phaeocystis, which forms large blooms in the coastal waters of the Southern North Sea, some aspects of the taxonomy and biology of this species still suffer from a sketchy knowledge. It is currently admitted that P. globosa is the species that blooms in the Southern North Sea. This has however, never been confirmed by SSU rDNA sequencing which constitutes nowadays, together with the morphology of the haploid flagellate, a reliable taxonomic criterion to distinguish between Phaeocystis species. Also, although the fine morphology of the haploid scaly flagellate is well known, there is a lack of comparable and harmonized description of the other cell types, i.e. colonial cells and diploid flagellates, previously identified within the Phaeocystis life cycle. In this study, we used SSU rDNA sequencing, light and electron scanning microscopy and flow cytometry to identify and characterize three cell types produced in controlled and reproducible manner from two strains of Phaeocystis isolated from the Belgian coastal zone. Our morphometry and sequencing data confirm unambiguously that P. globosa is the species that blooms in the Southern North Sea, but suggest in addition that both strains are representative of the original P. globosa Scherffel. Our study compares, for the first time since the species description, the fine morphometry and ploidy features of diploid colonial cells, diploid and haploid flagellates originating from same strains, providing therefore unambiguous identification criteria for distinguishing them from each other. The diploid stage, colonial or flagellated cell, is thus characterized by a naked surface, has a size range nearly twice that of the haploid flagellate and do not produce the chitinous filaments specific of the haploid stage. Colonial cells lack flagella and haptonema but possess on their apical side two appendages, which elongate to form the flagella of the diploid flagellate., SCOPUS: ar.j, info:eu-repo/semantics/published

This paper presents an optimal LQR control for a static-series compensator (SSC) and propounds a design criterion for the choice of the LQR weights in order to mitigate grid-voltage dips. The authors present a SSC state-space model that considers the modelling of grid, transformer and R-L load. The proposed control works in the Stationary-Reference Frames (SRF) and implements AFC resonant controllers, allowing the direct control of unbalanced dips in a three wire grid-load connection., Postprint (published version)

We theoretically investigate how phase-only spatial light modulation can enable controlling and focusing the second-harmonic light generated in transparent nonlinear random structures. The studied structures are composed of domains with random sizes and antiparallel polarization, which accurately model widely used ferroelectric crystals such as strontium barium niobate. Using a first-principles Green-function formalism, we account for the effect that spatial light modulation of the fundamental beam introduces into the second-order nonlinear frequency conversion occurring in the considered class of structures. This approach provides a complete description of the physical origin of the second-harmonic light generation in the system, as well as the optimization of the light intensity in any arbitrary direction. Our numerical results show how the second-harmonic light is influenced by both the disorder in the structure and the boundaries of the crystal. Particularly, we find that the net result from the interplay between disorder and boundary effects is strongly dependent on the dimensions of the crystal and the observation direction. Remarkably, our calculations also show that although in general the maximum possible enhancement of the second-order light is the same as the one corresponding to linear light scattering in turbid media, in the Cerenkov phase matching direction the enhancement can exceed the linear limit. The theoretical analysis presented in this work expands the current understanding of light control in complex media and could contribute to the development of a new class of imaging and focusing techniques based on nonlinear frequency mixing in random optical materials., Peer Reviewed, Postprint (published version)

Summary: The purpose of this study was to examine the relationship between teacher retention and student achievement as measured by the Florida Comprehensive Achievement Test (FCAT) Math Developmental Scale Scores (DSS). This study examined the impact of teacher transience on high school student math scores over a three-year period and considered the effect of teacher years of experience in relation to transience and achievement. For the purposes of this study teachers were identified into the following four classifications: Stayers, Within District Movers, Cross District Movers, or Beginning teachers. The findings indicated that students of beginning teachers scored significantly lower on the ninth grade math test than students of teachers in the other three classifications. At the 10th grade level there was no significant difference among the teacher transience groups. Based upon the findings, the following conclusion resulted from the study. Since an analysis of the data indicated that teacher retention is likely to improve ninth grade student score gains on the FCAT Math assessment, it is recommended that High School administrators carefully review the teaching assignments of ninth grade math teachers, especially in this era of high stakes testing and accountability., by Francisco J. Rodrâiguez., Thesis (Ed.D.)--Florida Atlantic University, 2009., Includes bibliography., Electronic reproduction. Boca Raton, Fla., 2009. Mode of access: World Wide Web.