Fourth order Superintegrable systems separating in Cartesian coordinates I. Exotic quantum potentials

A study is presented of two-dimensional superintegrable systems separating in Cartesian coordinates and allowing an integral of motion that is a fourth order polynomial in the momenta. All quantum mechanical potentials that do not satisfy any linear differential equation are found. They do however satisfy nonlinear ODEs. We show that these equations always have the Painlev\'e property and integrate them in terms of known Painlev\'e transcendents or elliptic functions.Comment: 36 page

A New MMC Topology Which Decreases the Sub Module Voltage Fluctuations at Lower Switching Frequencies and Improves Converter Efficiency

Modular Multi-level inverters (MMCs) are becoming more common because of their suitability for applications in smart grids and multi-terminal HVDC transmission networks. The comparative study between the two classic topologies of MMC (AC side cascaded and DC side cascaded topologies) indicates some disadvantages which can affect their performance. The sub module voltage ripple and switching losses are one of the main issues and the reason for the appearance of the circulating current is sub module capacitor voltage ripple. Hence, the sub module capacitor needs to be large enough to constrain the voltage ripple when operating at lower switching frequencies. However, this is prohibitively uneconomical for the high voltage applications. There is always a trade off in MMC design between the switching frequency and sub module voltage ripple

Self- assessment and Portfolio Production of Iranian EFL Learners

AbstractThe purpose of this study was to investigate the effect of self-assessment on Iranian EFL students’ portfolio production. The experimental group was given the introduction to self-assessment which included a self-assessment guide, while the control group would not received the self-assessment guide and would not be exposed to any training during this research project. The experimental group outperformed the control group and the differences were statistically significant. Students engage in constant critical thinking and develop a strong sense of responsibility. For teachers, introducing self-assessment as a structured, formal practice will encourage students’ involvement and lead to a highly learner-centered classroom

Role of the homeobox HESX1/HESX1 in forebrain and pituitary development in mouse and human

The homeobox gene Hesx1 encodes a transcriptional repressor that is required, within the anterior neural plate of the vertebrate embryo, for normal forebrain and pituitary development. Hesx1'' mice display variable defects, affecting midline telencephalic commissural tracts, the eyes and the pituitary gland. In humans, mutations in HESX1 are associated with hypopituitarism and septo-optic dysplasia (SOD), a condition characterised by pituitary abnormalities in association with midline telencephalic structure and optic nerve defects. In this thesis, a dual approach was used, in order to gain insights into HESX1 function. Firstly, a yeast two-hybrid screen identified DNMT1, LONP2, SRFBP1, SAFB1 and ZFP592 as protein partners of HESX1. Mapping of the interacting regions indicated that different domains of HESX1 are involved in each of these interactions. The five proteins co-localise with HESX1 in the nucleus and their transcripts are co-expressed with Hesxl in mouse embryos. Furthermore, these interactions are disrupted by various HESX1 mutations. The binding with DNMT1 was characterised in more detail, since this protein has a crucial role in gene silencing through its DNA methylation properties. Thus this interaction suggests a novel mechanism for the repressing activity of HESX1. Secondly, gene targeting was used to generate two knock-in mouse models, based on two autosomal recessive human HESX1 mutations, I26T and R160C. I26T has been associated with anterior pituitary hypoplasia in a patient, whilst R160C was identified in two siblings with SOD. Hesxl embryos display fully penetrant pituitary defects with frequent occurrence of eye abnormalities, whereas the telencephalon develops normally. HesxlR160C/R160C embryos display more severe forebrain and pituitary defects that are identical to those observed in Hesxl' ' mice. These data indicate that Hesxl-I26T is a hypomorphic allele, whereas Hesxl-R160C yields a null allele and consequently causes a more severe phenotype in mice and humans