A Beckman-Quarles type theorem for linear fractional transformations of the extended double plane

In this presentation, we consider the problem of characterizing maps that preserve pairs of right hyperbolas or lines in the extended double plane whose hyperbolic angle of intersection is zero. We consider two disjoint spaces of right hyperbolas and lines in the extended double plane $\mathscr{H}^+$ and $\mathscr{H}^-$ and prove that bijective mappings on the respective spaces that preserve tangency between pairs of hyperbolas or lines must be induced by a linear fractional transformation

RPSA, a candidate gene for isolated congenital asplenia, is required for pre-rRNA processing and spleen formation in Xenopus

A growing number of tissue-specific inherited disorders are associated with impaired ribosome production, despite the universal requirement for ribosome function. Recently, mutations in RPSA, a protein component of the small ribosomal subunit, were discovered to underlie approximately half of all isolated congenital asplenia cases. However, the mechanisms by which mutations in this ribosome biogenesis factor lead specifically to spleen agenesis remain unknown, in part due to the lack of a suitable animal model for study. Here we reveal that RPSA is required for normal spleen development in the frog, Xenopus tropicalis. Depletion of Rpsa in early embryonic development disrupts pre-rRNA processing and ribosome biogenesis, and impairs expression of the key spleen patterning genes nkx2-5, bapx1 and pod1 in the spleen anlage. Importantly, we also show that whereas injection of human RPSA mRNA can rescue both pre-rRNA processing and spleen patterning, injection of human mRNA bearing a common disease-associated mutation cannot. Together, we present the first animal model of RPSA-mediated asplenia and reveal a crucial requirement for RPSA in pre-rRNA processing and molecular patterning during early Xenopus development

The Drosophila G9a gene encodes a multi-catalytic histone methyltransferase required for normal development

Mammalian G9a is a histone H3 Lys-9 (H3–K9) methyltransferase localized in euchromatin and acts as a co-regulator for specific transcription factors. G9a is required for proper development in mammals as g9a(−)/g9a(−) mice show growth retardation and early lethality. Here we describe the cloning, the biochemical and genetical analyses of the Drosophila homolog dG9a. We show that dG9a shares the structural organization of mammalian G9a, and that it is a multi-catalytic histone methyltransferase with specificity not only for lysines 9 and 27 on H3 but also for H4. Surprisingly, it is not the H4–K20 residue that is the target for this methylation. Spatiotemporal expression analyses reveal that dG9a is abundantly expressed in the gonads of both sexes, with no detectable expression in gonadectomized adults. In addition we find a low but clearly observable level of dG9a transcript in developing embryos, larvae and pupae. Genetic and RNAi experiments reveal that dG9a is involved in ecdysone regulatory pathways

Immunopathological signatures in multisystem inflammatory syndrome in children and pediatric COVID-19

: Pediatric Coronavirus Disease 2019 (pCOVID-19) is rarely severe; however, a minority of children infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) might develop multisystem inflammatory syndrome in children (MIS-C), with substantial morbidity. In this longitudinal multi-institutional study, we applied multi-omics (analysis of soluble biomarkers, proteomics, single-cell gene expression and immune repertoire analysis) to profile children with COVID-19 (n = 110) and MIS-C (n = 76), along with pediatric healthy controls (pHCs; n = 76). pCOVID-19 was characterized by robust type I interferon (IFN) responses, whereas prominent type II IFN-dependent and NF-κB-dependent signatures, matrisome activation and increased levels of circulating spike protein were detected in MIS-C, with no correlation with SARS-CoV-2 PCR status around the time of admission. Transient expansion of TRBV11-2 T cell clonotypes in MIS-C was associated with signatures of inflammation and T cell activation. The association of MIS-C with the combination of HLA A*02, B*35 and C*04 alleles suggests genetic susceptibility. MIS-C B cells showed higher mutation load than pCOVID-19 and pHC. These results identify distinct immunopathological signatures in pCOVID-19 and MIS-C that might help better define the pathophysiology of these disorders and guide therapy

Technology‐based instrumental activities of daily living in persons with Alzheimer's disease and related disorders

Abstract INTRODUCTION Instrumental activities of daily living (iADLs) increasingly involve technology (e.g., making payments online, texting). The current study examined the applicability and diagnostic accuracy of technology‐based iADLs in those evaluated for Alzheimer's disease and related dementias (ADRD). METHODS A total of 264 care partners of persons undergoing comprehensive interdisciplinary evaluations completed the Functional Activities Questionnaire and 11 technology‐based iADL items. RESULTS Technology‐based iADLs applied to more than 80% of patients. Average dependence on technology‐based items was overall less than for traditional iADLs. The addition of technology‐based items to traditional iADL items slightly improved the ability to identify individuals with dementia. When considered separately, technology‐based iADL items demonstrated comparable ability to distinguish between diagnostic stages. DISCUSSION Technology use is common in older adults with ADRD for a range of daily activities. Accounting for technology use increases the content validity of existing iADL measures for the modern context and yields comparable diagnostic accuracy. Highlights Technology use is often integral to daily activity performance for individuals with Alzheimer's disease and related dementias (ADRD). Daily technologies, such as smartphones, were used frequently by those with ADRD. Many individuals were less dependent on technology activities than traditional activities. Adding technology questions slightly increased diagnostic accuracy for detecting dementia

Neutron Diffraction Measurements of Residual Stress and Mechanical Testing of Pressure Sintered Metal-Ceramic Composite Systems

Abstract. Functionally graded materials (FGMs) are composite materials which vary in phase composition, microstructure and properties over one or more dimensions. They are a good potential choice for nuclear reactor components as they can be engineered to effectively resist corrosion and radiation damage. In the case of a metal-ceramic FGM, they can mate the strength and ductility of a metal with the hardness and toughness of a ceramic. A series of composite samples of variable metal-ceramic ratios was manufactured by hot uniaxial pressing in cylinders. Bulk uniform samples of a certain composition were manufactured as a more efficient way of studying FGMs without the extreme gradient required in practical applications. Thermally and mechanically generated stresses, inherent in composites, frequently create conditions for micro-cracking development, depending on the material's micro-structural characteristics and the thermomechanical processing route. Bulk stress measurements in the prepared samples were carried out on the Kowari diffractometer on the OPAL reactor at ANSTO. Both phases -metal matrix and ceramic inclusions -were measured in both axial and lateral directions for full characterisation of the composite stress state. When compared against analytical evaluation, experimental results, for some samples, demonstrated significant stress relaxation with micro-cracking being the main suspect. Introduction Functionally graded materials (FGMs) were first proposed as an advanced engineering material in 1972, and have been actively pursued since then. They are proposed in areas such as biomaterials, aerospace, chemical plants, mining and building material commoditie