646 research outputs found
Quantum Rod Emission Coupled to Plasmonic Lattice Resonances: A Collective Directional Source of Polarized Light
We demonstrate that an array of optical antennas may render a thin layer of
randomly oriented semiconductor nanocrystals into an enhanced and highly
directional source of polarized light. The array sustains collective plasmonic
lattice resonances which are in spectral overlap with the emission of the
nanocrystals over narrow angular regions. Consequently, different photon
energies of visible light are enhanced and beamed into definite directions.Comment: 4 pages, 3 figure
The Belgian PCB and dioxin incident of January-June 1999: exposure data and potential impact on health.
In January 1999, 500 tons of feed contaminated with approximately 50 kg of polychlorinated biphenyls (PCBs) and 1 g of dioxins were distributed to animal farms in Belgium, and to a lesser extent in the Netherlands, France, and Germany. This study was based on 20,491 samples collected in the database of the Belgian federal ministries from animal feed, cattle, pork, poultry, eggs, milk, and various fat-containing food items analyzed for their PCB and/or dioxin content. Dioxin measurements showed a clear predominance of polychlorinated dibenzofuran over polychlorinated dibenzodioxin congeners, a dioxin/PCB ratio of approximately 1:50,000 and a PCB fingerprint resembling that of an Aroclor mixture, thus confirming contamination by transformer oil rather than by other environmental sources. In this case the PCBs contribute significantly more to toxic equivalents (TEQ) than dioxins. The respective means +/- SDs and the maximum concentrations of dioxin (expressed in TEQ) and PCB observed per gram of fat in contaminated food were 170.3 +/- 487.7 pg, 2613.4 pg, 240.7 +/- 2036.9 ng, and 51059.0 ng in chicken; 1.9 +/- 0.8 pg, 4.3 pg, 34.2 +/- 30.5 ng, and 314.0 ng in milk; and 32.0 +/- 104.4 pg, 713.3 pg, 392.7 +/- 2883.5 ng, and 46000.0 ng in eggs. Assuming that as a consequence of this incident between 10 and 15 kg PCBs and from 200 to 300 mg dioxins were ingested by 10 million Belgians, the mean intake per kilogram of body weight is calculated to maximally 25,000 ng PCBs and 500 pg international TEQ dioxins. Estimates of the total number of cancers resulting from this incident range between 40 and 8,000. Neurotoxic and behavioral effects in neonates are also to be expected but cannot be quantified. Because food items differed widely (more than 50-fold) in the ratio of PCBs to dioxins, other significant sources of contamination and a high background contamination are likely to contribute substantially to the exposure of the Belgian population
Laser-UV-microirradiation of interphase nuclei and posttreatment with caffeine: a new approach to establish the arrangement of interphase chromosomes
Laser UV microirradiation of Chinese hamster interphase cells combined with caffeine post-treatment produced different patterns of chromosome damage in mitosis following irradiation of a small area of the nucleus that may be classified in three categories: I) intact metaphase figures, II) chromosome damage confined to a small area of the metaphase spread, III) mitotic figures with damage on all chromosomes. Category III might be the consequence of a non-localized distortion of nuclear metabolism. By contrast, category II may reflect localized DNA damage induced by microirradiation, which could not be efficiently repaired due to the effect of caffeine. If this interpretation is right, in metaphase figures of category II chromosome damage should occur only at the irradiation site. The effect might then be used to investigate neighbourhood relationships of individual chromosomes in the interphase nucleus
Sex chromosome positions in human interphase nuclei as studied by in situ hybridization with chromosome specific DNA probes
Two cloned repetitive DNA probes, pXBR and CY1, which bind preferentially to specific regions of the human X and Y chromosome, respectively, were used to study the distribution of the sex chromosomes in human lymphocyte nuclei by in situ hybridization experiments. Our data indicate a large variability of the distances between the sex chromosomes in male and female interphase nuclei. However, the mean distance observed between the X and Y chromosome was significantly smaller than the mean distance observed between the two X-chromosomes. The distribution of distances determined experimentally is compared with three model distributions of distances, and the question of a non-random distribution of sex chromosomes is discussed. Mathematical details of these model distributions are provided in an Appendix to this paper. In the case of a human translocation chromosome (XqterXp22.2::Yq11Y qter) contained in the Chinese hamster x human hybrid cell line 445 x 393, the binding sites of pXBR and CY1 were found close to each other in most interphase nuclei. These data demonstrate the potential use of chromosome-specific repetitive DNA probes to study the problem of interphase chromosome topography
Cutting our own keys: New possibilities of neurodivergent storying in research
Increasingly, neurodivergent people are sharing their own narratives and conducting their own research. Prominent individuals have integrated the ‘nothing about us without us’ slogan, used by neurodivergent and other disabled social activists, into academia. This article imagines a neuromixed academia. We consider how to work through challenges present in neuromixed encounters; to support cross-neurotype communication and pave the way for an ethos of community and collaboration. We explore how we might create a space in which neurodivergent experiences are seen as just one part of our complex and multifaceted identities. We do this through the process of ‘cutting our own keys’, to try out new possibilities of neurodivergent storying aimed at finding ourselves in our own stories about neurodivergence. This involves borrowing and developing methodological approaches formulated outside of research on different forms of neurodivergence, and to invent our own concepts based on our own embodied experiences and the social worlds we inhabit. Throughout, we mingle our own autoethnographic accounts in relation to research accounts and theories, as a way of illustrating the work with the text as a thinking about neurodivergence with each other in itself.
Lay abstract
A lot of people who do research are also neurodivergent (such as being autistic or attention deficit hyperactivity disorder), but neurodivergent people do not always feel welcome in research spaces which are often shaped around neurotypical people. Some neurotypical researchers lack confidence in talking to neurodivergent people, and others feel like neurodivergent people might not be able to do good research about other people who are like them without being biased. We think it is important that all researchers are able to work well together, regardless of whether they are neurotypical, autistic, or attention deficit hyperactivity disorder (or any other neurotype) – in truly ‘neurodiverse’ teams. In this article we talk about how to create better spaces for all researchers, where we feel valued for who we are and take each others’ needs into account. We do this using some approaches from other areas of research and talking about how they relate to our personal experiences of being neurodivergent researchers with our own personal stories. This article adds to a growing work on how we can work with people who are different from us, in more respectful and kind ways
Estimating the atmospheric concentration of Criegee intermediates and their possible interference in a FAGE-LIF instrument
We analysed the extensive dataset from the HUMPPA-COPEC 2010 and the HOPE 2012 field campaigns in the boreal forest and rural environments of Finland and Germany, respectively, and estimated the abundance of stabilised Criegee intermediates (SCIs) in the lower troposphere. Based on laboratory tests, we propose that the background OH signal observed in our IPI-LIF-FAGE instrument during the aforementioned campaigns is caused at least partially by SCIs. This hypothesis is based on observed correlations with temperature and with concentrations of unsaturated volatile organic compounds and ozone. Just like SCIs, the background OH concentration can be removed through the addition of sulfur dioxide. SCIs also add to the previously underestimated production rate of sulfuric acid. An average estimate of the SCI concentration of ∼ 5.0 x 104 molecules cm−3 (with an order of magnitude uncertainty) is calculated for the two environments. This implies a very low ambient concentration of SCIs, though, over the boreal forest, significant for the conversion of SO2 into H2SO4. The large uncertainties in these calculations, owing to the many unknowns in the chemistry of Criegee intermediates, emphasise the need to better understand these processes and their potential effect on the self-cleaning capacity of the atmosphere
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COVID-19 Roundtable
The past year was an unprecedentedly challenging period to humanity. The very concept of a pandemic indicates a profound impact across different regions and societal strata, rendering the idea of unscathed human lives almost unimaginable. Still, this image of COVID-19 as a global threat menacing us all must not be allowed to efface the specificity of individual or communal struggles. This caveat is particularly relevant in the context of gender and diversity studies – the pertinence of which has been underscored countlessly over the past months, especially in policy recommendations to the COVID-19 pandemic. From the disproportionately severe measures aggravating isolation and destitution among the elderly to the coalescence of sanitary regulations and the BLM protests or the fire in the Moria refugee camp and the resulting urgency to address the wellbeing of displaced people: issues that relate intimately to notions of marginalization continually surface adjacent to the health crisis proper. Whether explicitly or implicitly, these circumstances call for gender and diversity scholars to commit their expertise to the benefit of those inordinately affected by COVID-19 and the array of responses it has evoked worldwide. At the same time, the conditions affecting these groups and individuals also affect research activities and advocacy work on gender and diversity, inhibiting the active commitment and scholarly involvement the situation demands. In this Spring 2021 General Issue, the Journal of Diversity and Gender Studies (DiGeSt) sought to explore the paradoxes, contradictions and tensions scholars in our field have faced and continue to face during the current COVID-19 crisis. Transcending a formally academic register, the roundtable includes personal, situated accounts that engage tensions between the pandemic and scholarly work in diversity and gender studies
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