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Search Results: 1 - 10 of 4476 matches for " Johannes Burger "
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Comparison of electromagnetic field solvers for the 3D analysis of plasmonic nano antennas
Johannes Hoffmann,Christian Hafner,Patrick Leidenberger,Jan Hesselbarth,Sven Burger
Physics , 2009, DOI: 10.1117/12.828036
Abstract: Plasmonic nano antennas are highly attractive at optical frequencies due to their strong resonances - even when their size is smaller than the wavelength - and because of their potential of extreme field enhancement. Such antennas may be applied for sensing of biological nano particles as well as for single molecule detection. Because of considerable material losses and strong dispersion of metals at optical frequencies, the numerical analysis of plasmonic antennas is very demanding. An additional difficulty is caused when very narrow gaps between nano particles are utilized for increasing the field enhancement. In this paper we discuss the main difficulties of time domain solvers, namely FDTD and FVTD and we compare various frequency domain solvers, namely the commercial FEM packages JCMsuite, Comsol, HFSS,and Microwave Studio with the semi-analytic MMP code that may be used as a reference due to its fast convergence and high accuracy.
Participation and Activity Rates: Monitoring Exposure Potential for Native Americans and Others in the United States  [PDF]
Joanna Burger
Journal of Environmental Protection (JEP) , 2011, DOI: 10.4236/jep.2011.28116
Abstract: Managers and regulators are concerned about potential human health effects from exposure on lands contaminated by chemicals and radionuclides. Determining target cleanup levels is partly dependent upon future land use, and potential exposure from human use. This paper provides data from surveys of activity patterns of people attending festivals in four states, located in the vicinity of Department of Energy facilities. There were significant differences in both participation rates, and activity rates as a function of both location and ethnicity that can be used by managers to track exposure, land use, and preferred activities on natural lands. In general, 1) a higher percent of Native Americans engaged in consumptive activities than others, 2) a higher percent of Caucasians engaged in some non-consumptive activities than Native Americans, 3) a higher percentage of Native Americans engaged in activities on sacred grounds, 4) activity rates were generally higher for Native Americans for consumptive activities and religious/cultural than for Caucasians, 5) fishing rates were higher than other consumptive activities, and camping/hiking were higher than other non-con- sumptive activities, and 6) hunting rates were higher in subjects from Idaho than elsewhere. Baseline human use is critical for monitoring potential exposure, and provides the basis for monitoring, risk assessment and future land use, and these data can be used by managers for assessment and management. Tracking changes over time will reflect changing recreational, subsistence, and cultural/religious trends that relate to land use, public perceptions, and exposure.
Biological Effects of Cigarette Smoke in Cultured Human Retinal Pigment Epithelial Cells
Alice L. Yu, Kerstin Birke, Johannes Burger, Ulrich Welge-Lussen
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048501
Abstract: The goal of the present study was to determine whether treatment with cigarette smoke extract (CSE) induces cell loss, cellular senescence, and extracellular matrix (ECM) synthesis in primary human retinal pigment epithelial (RPE) cells. Primary cultured human RPE cells were exposed to 2, 4, 8, and 12% of CSE concentration for 24 hours. Cell loss was detected by cell viability assay. Lipid peroxidation was assessed by loss of cis-parinaric acid (PNA) fluorescence. Senescence-associated ?-galactosidase (SA-?-Gal) activity was detected by histochemical staining. Expression of apolipoprotein J (Apo J), connective tissue growth factor (CTGF), fibronectin, and laminin were examined by real-time PCR, western blot, or ELISA experiments. The results showed that exposure of cells to 12% of CSE concentration induced cell death, while treatment of cells with 2, 4, and 8% CSE increased lipid peroxidation. Exposure to 8% of CSE markedly increased the number of SA-?-Gal positive cells to up to 82%, and the mRNA expression of Apo J, CTGF, and fibronectin by approximately 3–4 fold. Treatment with 8% of CSE also increased the protein expression of Apo J and CTGF and the secretion of fibronectin and laminin. Thus, treatment with CSE can induce cell loss, senescent changes, and ECM synthesis in primary human RPE cells. It may be speculated that cigarette smoke could be involved in cellular events in RPE cells as seen in age-related macular degeneration.
A Conceptual Framework Evaluating Ecological Footprints and Monitoring Renewable Energy: Wind, Solar, Hydro, and Geothermal  [PDF]
Joanna Burger, Michael Gochfeld
Energy and Power Engineering (EPE) , 2012, DOI: 10.4236/epe.2012.44040
Abstract: With worldwide increases in energy consumption, and the need to increase reliance on renewable energy, we must examine ecological footprints of each energy source, as well as its carbon emissions. Renewable energy sources (wind, solar, hydro, geothermal) are given as the best examples of “green” energy sources with low carbon emissions. We provide a conceptual model for examining the ecological footprint of energy sources, and suggest that each resource needs continued monitoring to protect the environment, and ultimately human health. The effects and consequences of ecological footprint need to be considered in terms of four-compartments: underground (here defined as geoshed), surface, airshed, and atmosphere. We propose a set of measurement endpoints (metrics may vary), in addition to CO2 footprint, that are essential to evaluate the ecological and human health consequences of different energy types. These include traditional media monitoring (air, water, soil), as well as ecological footprints. Monitoring human perceptions of energy sources is also important for energy policy, which evolves with changes in population density, technologies, and economic consequences. While some assessment endpoints are specific to some energy sectors, others can provide crosscutting information allowing the public, communities and governments to make decisions about energy policy and sustainability.
Knowledge and Perceptions of Energy Alternatives, Carbon and Spatial Footprints, and Future Energy Preferences within a University Community in Northeastern US  [PDF]
Joanna Burger, Michael Gochfeld
Energy and Power Engineering (EPE) , 2013, DOI: 10.4236/epe.2013.54033
Abstract:

Our overall research aim was to examine whether people distinguished between the spatial footprint and carbon footprint of different energy sources, and whether their overall “worry” about energy types was related to future developed of these types. We surveyed 451 people within a university community regarding knowledge about different energy sources with regard to renewability and spatial and carbon footprints and attitudes about which energy type(s) should be developed further. Findings were: 1) Gas, oil and coal were rated as the least renewable, and wind, solar and hydro as the most renewable; 2) Oil and coal were rated as having the largest carbon footprint, while wind, solar and tidal were rated the lowest; 3) There were smaller differences in ratings for spatial footprints, probably reflecting unfamiliarity with the concept, although oil and gas were rated the highest; 4) Energy sources viewed as renewable were favored for future development compared with non-renewable energy sources, and coal and oil were rated the lowest; 5) Worry-free sources such as solar were favored; and 6) There were some age-related differences, but they were small, and there were no gender-related differences. Overall, subjects knew more about carbon footprints than spatial footprints, generally correctly identified renewable and non-renewable sources, and wanted future energy development for energy sources which were less worried about (e.g. solar, wind). These perceptions require in-depth examination in a large sample from different areas of the country.

The Neuron as a Controlled Toggle Circuit  [PDF]
John Robert Burger
Circuits and Systems (CS) , 2014, DOI: 10.4236/cs.2014.512032
Abstract: This paper considers a model of a recursive neuron whose circuit the author finds interesting, not because of its financial possibility, but because of its surprising electrical behavior. Below, a recursive neuron is modeled with excitatory and inhibitory triggering, and simulated using Win Spice. This model is shown to be capable of controlled toggling, and so promises energy-efficient, massively parallel computing.
Shorebirds, Stakeholders, and Competing Claims to the Beach and Intertidal Habitat in Delaware Bay, New Jersey, USA  [PDF]
Joanna Burger, Lawrence Niles
Natural Science (NS) , 2017, DOI: 10.4236/ns.2017.96019
Abstract:
Birds have specific habitat needs as a function of their life cycle and reproductive stage. Migrant shorebirds that may fly from the Arctic to the southern tip of South America have foraging and habitat requirements at sites where they stop to refuel before continuing their migration north or south. Throughout the world, shorebirds mainly forage on mudflats at low tide. Red knots (Calidris canutus rufa) are threatened in the United States and elsewhere, and it is critical to determine factors that might contribute to their decline. This paper uses Delaware Bay as a case study to examine shorebird (and red knot) use of the intertidal habitat, and competing claims to habitats they require during their northward migration, as well as some of the key stakeholders that play a role in protecting red knots. Shorebirds are drawn to Delaware Bay to feed on the eggs of Horseshoe Crabs (Limulus polyphemus) that are concentrated at the high tide. But they also feed on the intertidal mudflat. We examined intertidal habitat use on 17 beaches in an extensive study in 2015, and 5 key beaches in 2016. Most of the beaches were longitudinal, but four were more complex, and were used extensively for resting as well as foraging; numbers there were higher than on the longitudinal beaches. On foraging beaches, some shorebirds were present on over 85% of the intertidal censuses, and red knots were present on over 48% of the intertidal censuses. Average numbers of red knots on the longitudinal beaches varied from 0 to 354 ± 116 when any shorebirds were present, but averaged up to 1184 ± 634 when knots were present in 2015. Some beaches in 2015 had no knots (a beach with long-term aquaculture). Tide, intertidal location, and beach (name) determined the number of knots (and all shorebirds). Numbers decreased with distance from the mean high tide line. The average number of knots present in the intertidal mudflats two hours before or after low tide when knots were present (e.g. no censuses with zeros) was 2040 (=maximum flock size, in 2015). Major threats to red knots are from recreationists, overfishing of horseshoe crabs (reduction in egg prey base), and use of the intertidal by aquaculture. We discuss the role of stakeholders in conservation and protection of red knots.
Cell contact interactions in rheumatology, The Kennedy Institute for Rheumatology, London, UK, 1-2 June 2000
Danielle Burger
Arthritis Research & Therapy , 2000, DOI: 10.1186/ar129
Abstract: The inflammatory site is the locus of many cellular interactions between specific tissue cells and infiltrating cells of the immune system. In RA many cell types participate in the pathogenic mechanisms that finally lead to tissue destruction (cartilage digestion and bone erosion). Among these cells T lymphocytes may play an important part, being the most abundant infiltrating cells in the pannus. Although T lymphocytes are claimed to participate in RA pathogenesis, knowledge of the mechanisms by which they exert their pathogenic effect(s) is still elusive. Monocyte-macrophages, the other main type of infiltrating cell in the pannus, play a crucial role because one of their main functions is to release various pro-inflammatory cytokines, including TNF-α, IL-1β, and IL-17, which participate in the induction of metalloproteinase (MMP) secretion by stromal cells (fibroblast-like synoviocytes) and osteoprotegerin ligand (OPGL) expression in osteoblasts. MMPs participate in cartilage digestion and OPGL induces maturation of osteoclasts, which are involved in bone resorption. The meeting was held to highlight some recent key advances in the intricate interactions between these cells. It was co-organized by Drs M Feldmann and F Brennan (Kennedy Institute for Rheumatology, London, UK) and Drs J-M Dayer and D Burger (Division of Immunology and Allergy, University Hospital, Geneva, Switzerland); 65 researchers from eight countries attended the meeting at the Kennedy Institute for Rheumatology. Three half-day sessions were organized, each with three main lectures and up to five short communications followed by a general discussion.The subject was introduced by Dr B Bresnihan (Department of Rheumatology, St Vincent's Hospital, Dublin, Ireland), who, as a clinical rheumatologist, pinpointed the relevance of T lymphocyte–monocyte–macrophage contact in RA pathogenesis. As less invasive biopsies are now possible, synovial tissue samples are more accessible, allowing direct analysis
Afrika in Afrikaans: Die beskouings van Herman Charle Bosman in Van Wyk Louw
W Burger
Tydskrif vir letterkunde , 2003,
Abstract: No
Taal as “ingang” tot die wêreld: reis, verbeelding, herinnering en identiteit na aanleiding van Breytenbach se A Veil of Footsteps
W Burger
Tydskrif vir letterkunde , 2009,
Abstract: Travelling is a central motive in A Veil of Footsteps (and in Breytenbach’s oeuvre). In this work, travelling is a metaphor for imagination. Breytenbach pleads for continual travelling because “the earth needs to be discovered and remembered again and again”. Breytenbach suggests that discovery and remembering require imagination. In the first part of this article the dependancy of imagination on language (the “footsteps” of the title) is investigated, using Paul Ricoeur’s concept of a “semantic imagination”. In the second part of the article three implications of imagination’s dependancy on language is identified in A Veil of Footsteps. Firstly the close tie between imagination and memory (the book is described as a memoir); secondly the importance of imagination for identity; and thirdly the need for imagination to enable an ethical response for one’s actions, are examined.
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