Multimode horn antennas for far-infrared astronomy

Multi-mode horns combined with bolometric or incoherent detectors are finding application in astronomical receivers for which partially coherent operation can provide increased throughput and thus sensitivity. This is advantageous when observing faint sources, especially if diffraction limited resolution is not required, or if the horn beam is truncated by a cold stop in the optical train. We discuss how such horns can be simulated and present examples from receiver instrumentation on the Planck and SPICA space telescopes

Polycomb Repressive Complex 2 (PRC2) Restricts Hematopoietic Stem Cell Activity

Polycomb group proteins are transcriptional repressors that play a central role in the establishment and maintenance of gene expression patterns during development. Using mice with an N-ethyl-N-nitrosourea (ENU)-induced mutation in Suppressor of Zeste 12 (Suz12), a core component of Polycomb Repressive Complex 2 (PRC2), we show here that loss of Suz12 function enhances hematopoietic stem cell (HSC) activity. In addition to these effects on a wild-type genetic background, mutations in Suz12 are sufficient to ameliorate the stem cell defect and thrombocytopenia present in mice that lack the thrombopoietin receptor (c-Mpl). To investigate the molecular targets of the PRC2 complex in the HSC compartment, we examined changes in global patterns of gene expression in cells deficient in Suz12. We identified a distinct set of genes that are regulated by Suz12 in hematopoietic cells, including eight genes that appear to be highly responsive to PRC2 function within this compartment. These data suggest that PRC2 is required to maintain a specific gene expression pattern in hematopoiesis that is indispensable to normal stem cell function

Variation and molecular evolution of HmbR, the Neisseria meningitidis haemoglobin receptor

Meningococcal disease caused by serogroup B Neisseria meningitidis remains an important health problem in many parts of the world, and there are currently no comprehensive vaccines. Poor immunogenicity, combined with immunological identity to human sialic acids, have hindered the development of a serogroup B conjugate vaccine, resulting in the development of alternative vaccine candidates, including many outer-membrane protein (OMP)-based formulations. However, the design of protein-based meningococcal vaccines is complicated by the high level of genetic and antigenic diversity of the meningococcus. Knowledge of the extent and structuring of this diversity can have implications for the use of particular proteins as potential vaccine candidates. With this in mind, the diversity of the meningococcal OMP HmbR was investigated among N. meningitidis isolates representative of major hyper-invasive lineages. In common with other meningococcal antigens, the genetic diversity of hmbR resulted from a combination of intraspecies horizontal genetic exchange and de novo mutation. Furthermore, genealogical analysis showed an association of hmbR genes with clonal complexes and the occurrence of two hmbR families, A and B. Three variable regions (VR1–VR3), located in loops 2, 3 and 4, were observed with clonal complex structuring of VR types. A minority of codons (3.9 %), located within putative surface-exposed loop regions of a 2D model, were under diversifying selection, indicating regions of the protein likely to be subject to immune attack

Characterization of the Contradictory Chromatin Signatures at the 3′ Exons of Zinc Finger Genes

The H3K9me3 histone modification is often found at promoter regions, where it functions to repress transcription. However, we have previously shown that 3′ exons of zinc finger genes (ZNFs) are marked by high levels of H3K9me3. We have now further investigated this unusual location for H3K9me3 in ZNF genes. Neither bioinformatic nor experimental approaches support the hypothesis that the 3′ exons of ZNFs are promoters. We further characterized the histone modifications at the 3′ ZNF exons and found that these regions also contain H3K36me3, a mark of transcriptional elongation. A genome-wide analysis of ChIP-seq data revealed that ZNFs constitute the majority of genes that have high levels of both H3K9me3 and H3K36me3. These results suggested the possibility that the ZNF genes may be imprinted, with one allele transcribed and one allele repressed. To test the hypothesis that the contradictory modifications are due to imprinting, we used a SNP analysis of RNA-seq data to demonstrate that both alleles of certain ZNF genes having H3K9me3 and H3K36me3 are transcribed. We next analyzed isolated ZNF 3′ exons using stably integrated episomes. We found that although the H3K36me3 mark was lost when the 3′ ZNF exon was removed from its natural genomic location, the isolated ZNF 3′ exons retained the H3K9me3 mark. Thus, the H3K9me3 mark at ZNF 3′ exons does not impede transcription and it is regulated independently of the H3K36me3 mark. Finally, we demonstrate a strong relationship between the number of tandemly repeated domains in the 3′ exons and the H3K9me3 mark. We suggest that the H3K9me3 at ZNF 3′ exons may function to protect the genome from inappropriate recombination rather than to regulate transcription

Information technology in geography and planning : including principles of GIS /

Includes indexes.Bibliography: p. [420]-435

The Effect of Single Accreditation on Medical Student Match Rates in Surgical Specialties

Introduction The year 2020 marked the first year in which a match under single accreditation took place. Both osteopathic (DO) and allopathic (MD) students would participate in the first match cycle without a dedicated DO match system. Our primary objective was to investigate how single accreditation has impacted the DO applicants attempting to match into surgical specialties. Our secondary objective was to investigate the impact of single accreditation at the program director (PD) level and whether or not this process would see a change in DO PD distribution in previously American Osteopathic Association (AOA)-approved programs. Method Information on number of applicants and post-match positions was gathered from AOA and National Residency Match Program (NRMP) websites. Credentials of PDs were obtained from the Accreditation Council on Graduate Medical Education website. Based on the available data, the following surgical specialties were compared for the years 2020, 2018, and 2016: General Surgery, Neurological Surgery (NSGY), Orthopedic Surgery, Otolaryngology/ENT (ENT), Plastic Surgery, and Thoracic Surgery. Data from 2016 were not included in the results as the AOA match results analysis was insufficient and unable to be directly compared to the NRMP data. Results of matched DO and MD applicants were compared using bivariate analysis. A p-value of \u3c0.05 was considered significant. Results From the year 2018 to 2020, the DO applicants saw a decrease of 3% in the total number of matched postgraduate year 1 spots in surgical specialties. NRMP results from 2020 saw that 51.7% of DO applicants matched and 67.7% (p \u3c 0.001) of MD applicants matched for the specialties examined. Percent of matched:applied for DO applicants was lower than MD applicants in the fields of NSGY (p \u3c 0.001), ENT (p \u3c 0.001), Plastic Surgery (p \u3c 0.001), General Surgery (p \u3c 0.001), and Thoracic Surgery (p = 0.011). After evaluating 60 former AOA General Surgery programs, 56% were found to have MD as PD. Another 26 former AOA surgical programs were investigated, and 58% were found to have MD PD. Conclusion Single accreditation has impacted the match process now that a large number of both MD and DO applicants are using the NRMP match system for postgraduate placement. Based on the available data, our results indicate that in the examined surgical specialties, there is a statistically significant difference in the number of MD and DO residents

Cognitive Screening for Young Children: Development and Diversity in Learning Contexts

SYSTEMS 1 is a screen of general cognitive functioning, for school age children that entails cognitive manipulation and information skills. Our aim was to extend the test for four and five year old children at pre-school, to estimate theoretical starting points in typical cognitive profiles, that are critical in the early years. Participants (N = 1164, girls/boys, 50%) were four to 11 years old (mean 7.9, sd 2.2) at pre-schools and schools in diverse socio-economic areas of Sydney. Children’s responses created the normative database, and the parameters were derived from curve estimation and regression procedures. Results suggest that cognitive screening is reliable and valid for younger and older children, and show a non-linear relation of children's test scores with age, that is characteristic of rapid change for younger children. The characteristic curve with the best fit to the data had a theoretical starting point before school age, at around 3 years of age. Findings are discussed in light of alternative models, and the clinical and educational applications