66 research outputs found

    Inner-city change in Pretoria: social and spatial trends

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    The Pretoria inner-city area and, more specifically, the high-density Sunnyside residential area have experienced major social and spatial changes since the mid-1990s. As in other metropolitan areas, the city’s spatial structure has been shaped by urban developmental processes such as decentralisation, desegregation and deconcentration. This article’s assessment of these changes in the context of the ways in which the inner city is transforming and positioning itself sheds some light on what we consider an inner-city success story in terms of adaptation to radical changes

    Melem (2,5,8-Triamino-tri-s-triazine), an Important Intermediate during Condensation of Melamine Rings to Graphitic Carbon Nitride:  Synthesis, Structure Determination by X-ray Powder Diffractometry, Solid-State NMR, and Theoretical Studies

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    Single-phase melem (2,5,8-triamino-tri-s-triazine) C6N7(NH2)3 was obtained as a crystalline powder by thermal treatment of different less condensed C−N−H compounds (e.g., melamine C3N3(NH2)3, dicyandiamide H4C2N4, ammonium dicyanamide NH4[N(CN)2], or cyanamide H2CN2, respectively) at temperatures up to 450°C in sealed glass ampules. The crystal structure was determined ab initio by X-ray powder diffractometry (Cu Kα1:  P21/c (No. 14), a = 739.92(1) pm, b = 865.28(3) pm, c = 1338.16(4) pm, β = 99.912(2)°, and Z = 4). In the solid, melem consists of nearly planar C6N7(NH2)3 molecules which are arranged into parallel layers with an interplanar distance of 327 pm. Detailed 13C and 15N MAS NMR investigations were performed. The presence of the triamino form instead of other possible tautomers was confirmed by a CPPI (cross-polarization combined with polarization inversion) experiment. Furthermore, the compound was characterized using mass spectrometry, vibrational (IR, Raman), and photoluminescence spectroscopy. The structural and vibrational properties of molecular melem were theoretically studied on both the B3LYP and the MP2 level. A structural optimization in the extended state was performed employing density functional methods utilizing LDA and GGA. A good agreement was found between the observed and calculated structural parameters and also for the vibrational frequencies of melem. According to temperature-dependent X-ray powder diffractometry investigations above 560°C, melem transforms into a graphite-like C−N material

    al-Köm al-aHmar / Särüna 1984

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    al-Köm al-aHmar / Särüna

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    Preference of pear psyllid (Cacopsylla pyri) for specific colour inspires new application in plant protection

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    Understanding the cues used by insects to select their hosts is essential for developing sustainable control strategies, particularly for plant disease vectors. Pear psyllids (Cacopsylla pyri) are vectors of the bacterial disease pear decline caused by ‘Candidatus Phytoplasma pyri’. Yellow sticky traps are typically used to monitor pest insects, but they are non-specific and capture many beneficial insects, too. Against the background of improving visual traps, this research aimed to investigate the colour choice behaviour of C. pyri. Our first approach was to screen insect colour preferences by performing choice assays with different LED colour wavelengths in a small-scale choice arena under controlled conditions. Over six LEDs tested, there was a strong significant preference of C. pyri for green 1 (532 nm) followed by green 2 (549 nm). Yellow (576 nm), orange (593 nm), red 1 (619 nm) and red 2 (633 nm) were less attractive than green. Subsequently, the trapping of pear psyllids was tested in the field using newly developed traps covered with transparent-coloured PVC sheets with a similar wavelength of the preferred LEDs. Red and completely transparent traps have been used as control and combined in randomized blocks in a pear orchard. Field trials revealed that green traps ranging from 525 to 537 nm attracted significantly more pear psyllids than longer wavelength green (543 nm), red and transparent ones. The construction of specific green-coloured sticky traps seems promising for improving psyllid trapping, especially during an early infestation at low population densities. Thus, these visual traps should be considered in future and integrated into psyllid monitoring as part of integrated pest management

    Melem (2,5,8-Triamino-tri- s

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    The NOD2 Single Nucleotide Polymorphisms rs2066843 and rs2076756 Are Novel and Common Crohn's Disease Susceptibility Gene Variants

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    Background: The aims were to analyze two novel NOD2 variants (rs2066843 and rs2076756) in a large cohort of patients with inflammatory bowel disease and to elucidate phenotypic consequences. Methodology/Principal Findings: Genomic DNA from 2700 Caucasians including 812 patients with Crohn's disease (CD), 442 patients with ulcerative colitis (UC), and 1446 healthy controls was analyzed for the NOD2 SNPs rs2066843 and rs2076756 and the three main CD-associated NOD2 variants p.Arg702Trp (rs2066844), p.Gly908Arg (rs2066847), and p.Leu1007fsX1008 (rs2066847). Haplotype and genotype-phenotype analyses were performed. The SNPs rs2066843 (p = 3.01×10−5, OR 1.48, [95% CI 1.23-1.78]) and rs2076756 (p = 4.01×10−6; OR 1.54, [95% CI 1.28-1.86]) were significantly associated with CD but not with UC susceptibility. Haplotype analysis revealed a number of significant associations with CD susceptibility with omnibus p values 0.9). However, in CD, SNPs rs2066843 and rs2076756 were more frequently observed than the other three common NOD2 mutations (minor allele frequencies for rs2066843 and rs2076756: 0.390 and 0.380, respectively). In CD patients homozygous for these novel NOD2 variants, genotype-phenotype analysis revealed higher rates of a penetrating phenotype (rs2076756: p = 0.015) and fistulas (rs2076756: p = 0.015) and significant associations with CD-related surgery (rs2076756: p = 0.003; rs2066843: p = 0.015). However, in multivariate analysis only disease localization (p<2×10−16) and behaviour (p = 0.02) were significantly associated with the need for surgery. Conclusion/Significance: The NOD2 variants rs2066843 and rs2076756 are novel and common CD susceptibility gene variants

    PBX1 is dispensable for neural commitment of RA-treated murine ES cells

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    Experimentation with PBX1 knockout mice has shown that PBX1 is necessary for early embryogenesis. Despite broad insight into PBX1 function, little is known about the underlying target gene regulation. Utilizing the Cre–loxP system, we targeted a functionally important part of the homeodomain of PBX1 through homozygous deletion of exon-6 and flanking intronic regions leading to exon 7 skipping in embryonic stem (ES) cells. We induced in vitro differentiation of wild-type and PBX1 mutant ES cells by aggregation and retinoic acid (RA) treatment and compared their profiles of gene expression at the ninth day post-reattachment to adhesive media. Our results indicate that PBX1 interactions with HOX proteins and DNA are dispensable for RA-induced ability of ES to express neural genes and point to a possible involvement of PBX1 in the regulation of imprinted genes

    Wahrheit – Geschwindigkeit – Pluralität

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    Neue Techniken zur Informationsübermittlung befördern den Informationsaustausch. Das ist eine für das 20. und 21. Jahrhundert ganz selbstverständliche Feststellung. Genauso selbstverständlich gilt sie aber auch für das 16. Jahrhundert und die Frühe Neuzeit insgesamt. Ein allseits bekanntes Beispiel dafür ist die Verbesserung der Techniken des Buchdrucks durch die Verwendung beweglicher Lettern. Dies führte dazu, dass neue Medien entstanden und sich dauerhaft etablierten, wie z.B. die Flugschrift und die „Neue Zeitung“. Andere bereits bekannte Genera wie Lieder und Predigten erhielten durch die veränderte Kommunikationssituation eine neue Bedeutung in den Auseinandersetzungen der Zeit. Daraus ergaben sich vielfältige Chancen und Heraus­forderungen, denn die Nutzung dieser neuen Medien wie die Transformation bestehender Medienformate und deren flächendeckende Verwendung setzte politische, soziale, juristische und religiöse Veränderungsprozesse in Gang bzw. beförderte sie.Die Beiträge des Sammelbandes möchten diese neuen Kommunikationsformen und -methoden ebenso wie die Veränderungsprozesse für das 16. Jahrhundert ausleuchten. Dies geschieht, indem Wandlungs- und Transformationsprozesse durch die Nutzung bekannter sowie die Schaffung neuer Medienformate, der Umgang mit Meinungsvielfalt und der damit einhergehenden Pluralität an Deutungen des Zeitgeschehens sowie die Entstehung einer neuen Streitkultur und neue Ordnungsversuche analysiert werden
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