32 research outputs found

    Effective actions, Wilson lines and the IR/UV mixing in noncommutative supersymmetric gauge theories

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    We study IR/UV mixing effects in noncommutative supersymmetric Yang-Mills theories with gauge group U(N) using background field perturbation theory. We compute three- and four-point functions of background fields, and show that the IR/UV mixed contributions to these correlators can be reproduced from an explicitly gauge-invariant effective action, which is expressed in terms of open Wilson lines.Comment: 23 pages, 8 figures. v2: new section and references added, effective action expressed only in terms of open Wilson lines operator

    Macrophages enhance Vegfa-driven angiogenesis in an embryonic zebrafish tumour xenograft model

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    Tumour angiogenesis has long been a focus of anti-cancer therapy; however, anti-angiogenic cancer treatment strategies have had limited clinical success. Tumour-associated myeloid cells are believed to play a role in the resistance of cancer towards anti-angiogenesis therapy, but the mechanisms by which they do this are unclear. An embryonic zebrafish xenograft model has been developed to investigate the mechanisms of tumour angiogenesis and as an assay to screen anti-angiogenic compounds. In this study, we used cell ablation techniques to remove either macrophages or neutrophils and assessed their contribution towards zebrafish xenograft angiogenesis by quantitating levels of graft vascularisation. The ablation of macrophages, but not neutrophils, caused a strong reduction in tumour xenograft vascularisation and time-lapse imaging demonstrated that tumour xenograft macrophages directly associated with the migrating tip of developing tumour blood vessels. Finally, we found that, although macrophages are required for vascularisation in xenografts that either secrete VEGFA or overexpress zebrafish vegfaa, they are not required for the vascularisation of grafts with low levels of VEGFA, suggesting that zebrafish macrophages can enhance Vegfa-driven tumour angiogenesis. The importance of macrophages to this angiogenic response suggests that this model could be used to further investigate the interplay between myeloid cells and tumour vascularisation

    Transparent soil to model thermal processes: An energy pile example

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    Managing energy resources is fast becoming a crucial issue of the 21st century, with groundbased heat exchange energy structures targeted as a viable means of reducing carbon emissions associated with regulating building temperatures. Limited information exists about the thermo-dynamic interactions of geothermal structures and soil owing to the practical constraints of placing measurement sensors in proximity to foundations; hence, questions remain about their long-term performance and interaction mechanics. An alternative experimental method using transparent soil and digital image analysis was proposed to visualize heat flow in soil. Advocating the loss of optical clarity as a beneficial attribute of transparent soil, this paper explored the hypothesis that temperature change will alter its refractive index and therefore progressively reduce its transparency, becoming more opaque. The development of the experimental methodology was discussed and a relationship between pixel intensity and soil temperature was defined and verified. This relationship was applied to an energy pile example to demonstrate heat flow in soil. The heating zone of influence was observed to extend to a radial distance of 1.5 pile diameters and was differentiated by a visual thermal gradient propagating from the pile. The successful implementation of this technique provided a new paradigm for transparent soil to potentially contribute to the understanding of thermo-dynamic processes in soil

    Infectious causes of microcephaly: epidemiology, pathogenesis, diagnosis, and management.

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    Microcephaly is an important sign of neurological malformation and a predictor of future disability. The 2015-16 outbreak of Zika virus and congenital Zika infection brought the world's attention to links between Zika infection and microcephaly. However, Zika virus is only one of the infectious causes of microcephaly and, although the contexts in which they occur vary greatly, all are of concern. In this Review, we summarise important aspects of major congenital infections that can cause microcephaly, and describe the epidemiology, transmission, clinical features, pathogenesis, management, and long-term consequences of these infections. We include infections that cause substantial impairment: cytomegalovirus, herpes simplex virus, rubella virus, Toxoplasma gondii, and Zika virus. We highlight potential issues with classification of microcephaly and show how some infants affected by congenital infection might be missed or incorrectly diagnosed. Although Zika virus has brought the attention of the world to the problem of microcephaly, prevention of all infectious causes of microcephaly and appropriately managing its consequences remain important global public health priorities

    Potential blindness: An unusual complication of lateral canthopexy

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    Lateral canthopexy is a commonly performed procedure in craniofacial and cosmetic surgery. In craniofacial surgery, lateral canthal fixation is performed in conjunction with a wide range of transcranial or subcranial procedures during the process of soft tissue re-suspension. A number of fixation materials have gained popular use. A case of craniofrontonasal dysplasia is reported in which a wire loop canthopexy fixation has become disengaged 3 months after a history of trauma and rotated to present a sharp surface against the sclera. Urgent surgical exploration prevented the apparently imminent complication of globe penetration with associated threat to vision

    Analysis of the Fgfr2C342Y mouse model shows condensation defects due to misregulation of Sox9 expression in prechondrocytic mesenchyme

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    Syndromic craniosynostosis caused by mutations in FGFR2 is characterised by developmental pathology in both endochondral and membranous skeletogenesis. Detailed phenotypic characterisation of features in the membranous calvarium, the endochondral cranial base and other structures in the axial and appendicular skeleton has not been performed at embryonic stages. We investigated bone development in the Crouzon mouse model (Fgfr2C342Y) at pre- and post-ossification stages to improve understanding of the underlying pathogenesis. Phenotypic analysis was performed by whole-mount skeletal staining (Alcian Blue/Alizarin Red) and histological staining of sections of CD1 wild-type (WT), Fgfr2C342Y/+ heterozygous (HET) and Fgfr2C342Y/C342Y homozygous (HOM) mouse embryos from embryonic day (E)12.5-E17.5 stages. Gene expression (Sox9, Shh, Fgf10 and Runx2) was studied by in situ hybridisation and protein expression (COL2A1) by immunohistochemistry. Our analysis has identified severely decreased osteogenesis in parts of the craniofacial skeleton together with increased chondrogenesis in parts of the endochondral and cartilaginous skeleton in HOM embryos. The Sox9 expression domain in tracheal and basi-cranial chondrocytic precursors at E13.5 in HOM embryos is increased and expanded, correlating with the phenotypic observations which suggest FGFR2 signalling regulates Sox9 expression. Combined with abnormal staining of type II collagen in pre-chondrocytic mesenchyme, this is indicative of a mesenchymal condensation defect. An expanded spectrum of phenotypic features observed in the Fgfr2C342Y/C342Y mouse embryo paves the way towards better understanding the clinical attributes of human Crouzon–Pfeiffer syndrome. FGFR2 mutation results in impaired skeletogenesis; however, our findings suggest that many phenotypic aberrations stem from a primary failure of pre-chondrogenic/osteogenic mesenchymal condensation and link FGFR2 to SOX9, a principal regulator of skeletogenesis
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