508 research outputs found
Observation of nonhexagonal superlattices in high-stage cesium intercalated graphite
Using a scanning transmission electron microscope with an electron beam size of âź800 Ă
, we have found that unsaturated cesium intercalated graphite at 98Âą2 K exhibits multiple structural phases with a typical domain size of âź1 Îźm. Electron diffraction patterns from individual structural islands were studied, and the p(2Ă2), p(3âĂ2), and p(3âĂ13âââ) in-plane superlattices were identified
Pseudomonas aeruginosa bacteraemia in an academic hospital in South Africa
This study aimed at determining the clinical manifestations, outcome and prognostic factors associated with P. aeruginosa bacteraemia at the Chris Hani Baragwanath Hospital during the period 1998-99; to describe and quantify resistance to anti-pseudomonal drugs, and characterization of bacteraemic isolates, investigate the genetic relationship among drug susceptible and multiply resistant strains in the hospital.
Clinical and laboratory investigations, culture and antimicrobial susceptibility testing were performed. Bacteraemic isolates were typed by endonuclease macrorestriction. Those with ≥97% band pattern similarity were assigned genotype status. Of 91 P. aeruginosa blood isolates, 52 (57%) were nosocomially acquired. Underlying conditions associated with episodes were burns in 24 (26.4%) and HIV infection in 21 (23%). Multi-drug resistance was present in 14 isolates (15.4%). Outcome was poor and death was associated with 36 (45.56%) of episodes. Case fatality rates were 60% in adults and 27.3% in children. Being a child, receiving appropriate antimicrobial treatment and admission to specialized care units were significantly associated with improved prognosis.
P. aeruginosa bacteraemia was associated with outbreaks caused by two multiply resistant genotypes. Eighteen, antimicrobial susceptible isolates from bacteraemic episodes in paediatric wards, 9 in HIV-seropositive children, could be linked to small outbreaks in both hospitalised and community-based children.
South African Medical Journal Vol. 98 (8) 2008: pp. 626-62
Polls and the political process: the use of opinion polls by political parties and mass media organizations in European postâcommunist societies (1990â95)
Opinion polling occupies a significant role within the political process of most liberal-capitalist societies, where it is used by governments, parties and the mass media alike. This paper examines the extent to which polls are used for the same purposes in the post-communist countries of Central and Eastern Europe, and in particular, for bringing political elites and citizens together. It argues that these political elites are more concerned with using opinion polls for gaining competitive advantage over their rivals and for reaffirming their political power, than for devolving political power to citizens and improving the general processes of democratization
Reproductive Biology of the Cape Honeybee: A Critique of Beekman et al: A critique of "Asexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexually,â authors: Madeleine Beekman, Michael H. Allsopp, Julianne Lim, Frances Goudie, and Benjamin P. Oldroyd. Journal of Heredity. 2011:102(5):562-566
Laying workers of the Cape honeybee parthenogenetically produce female offspring, whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in Apis mellifera capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator, and we therefore suggest that these "homozygousâ larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeder
Pion-Muon Asymmetry Revisited
Long ago an unexpected and unexplainable phenomena was observed. The
distribution of muons from positive pion decay at rest was anisotropic with an
excess in the backward direction relative to the direction of the proton beam
from which the pions were created. Although this effect was observed by several
different groups with pions produced by different means, the result was not
accepted by the physics community, because it is in direct conflict with a
large set of other experiments indicating that the pion is a pseudoscalar
particle. It is possible to satisfy both sets of experiments if helicity-zero
vector particles exist and the pion is such a particle. Helicity-zero vector
particles have direction but no net spin. For the neutral pion to be a vector
particle requires an additional modification to conventional theory as
discussed herein. An experiment is proposed which can prove that the asymmetry
in the distribution of muons from pion decay is a genuine physical effect
because the asymmetry can be modified in a controllable manner. A positive
result will also prove that the pion is NOT a pseudoscalar particle.Comment: 9 pages, 3 figure
Aberration-corrected electron microscopy of nanoparticles
The early history of scanning transmission electron microscopy (STEM) is reviewed as a way to frame the technical issues that make aberration correction an essential upgrade for the study of nanoparticles using STEM. The principles of aberration correction are
explained, and the use of aberration-corrected microscopy in the study of nanostructures is exemplified in order to remark the features and challenges in the use of this measuring techniqu
Prime beef cuts : culinary images for thinking 'men'
The paper contributes to scholarship theorising the sociality of the brand in terms of subject positions it makes possible through drawing upon the generative context of circulating discourses, in this case of masculinity, cuisine and celebrity. Specifically, it discusses masculinity as a socially constructed gender practice (Bristor and Fischer, 1993), examining materialisations of such practice in the form of visualisations of social relations as resources for 'thinking gender' or 'doing gender'. The transformative potential of the visualisations is illuminated by exploring the narrative content choreographed within a series of photographic images positioning the market appeal of a celebrity chef through the medium of a contemporary lifestyle cookery book. We consider how images of men 'doing masculinity'are not only channelled into reproducing existing gender hierarchy and compulsory heterosexuality in the service of commercial ends, but also into disrupting such enduring stereotyping through subtle reframing. We acknowledge that masculinity is already inscribed within conventionalised representations of culinary culture. In this case we consider how traces of masculinity are exploited and reinscribed through contemporary images that generate resources for rethinking masculine roles and identities, especially when viewed through the lens of stereotypically feminised pursuits such as shopping, food preparation, cooking, and the communal intimacy of food sharing. We identify unsettling tensions within the compositions, arguing that they relate to discursive spaces between the gendered positions written into the images and the popular imagination they feed off. Set against landscapes of culinary culture, we argue that the images invoke a brand of naively roughish "laddishness" or "blokishness", rendering it in domesticated form not only as benign and containable, but fashionable, pliable and, importantly, desirable. We conclude that although the images draw on stereotypical premeditated notions of a feral, boisterous and untamed heterosexual masculinity, they also set in motion gender-blending narratives
Reproductive Biology of the Cape Honeybee: A Critique of Beekman et al.
A critique of âAsexually Produced Cape Honeybee Queens (Apis mellifera capensis) Reproduce Sexuallyâ: Laying workers of the Cape honeybee parthenogenetically produce female offspring whereas queens typically produce males. Beekman et al. confirm this observation, which has repeatedly been reported over the last 100 years including the notion that natural selection should favor asexual reproduction in A. m. capensis. They attempt to support their arguments with an exceptionally surprising finding that A. m. capensis queens can parthenogenetically produce diploid homozygous queen offspring (homozygous diploid individuals develop into diploid males in the honeybee). Beekman et al. suggest that these homozygous queens are not viable because they did not find any homozygous individuals beyond the third larval instar. Even if this were true, such a lethal trait should be quickly eliminated by natural selection. The identification of sex (both with molecular and morphological markers) is possible but notoriously difficult in honeybees at the early larval stages. Ploidy is however a reliable indicator and we therefore suggest that these âhomozygousâ larvae found in queen cells are actually drones reared from unfertilized eggs, a phenomenon well known by honeybee queen breeders.http://www.ncbi.nlm.nih.gov/pubmed/22581844ab201
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