211 research outputs found

    Current Status of the Norman Site, 34WG2

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    As defined by Finkelstein in his description of excavations at the site, the Norman site currently is completely located within the waters of Fort Gibson Reservoir, a U.S. Army Corps of Engineers (COE) lake on the Grand (Neosho) River in northeastern Oklahoma. Due to a combination of archeological excavations at the site during the 1930s and 1940s, pothunting, large-scale earthmoving activities associated with the construction of a nearby highway bridge, and approximately 50 years of wave action and seasonal inundation by Fort Gibson Reservoir, portions of Mounds I-1 and I-2 are all that remain of the Norman site

    Associational Discrimination: How Far Can it Go?

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    Impacts of Climate Change on European Critical Infrastructures: The Case of the Power Sector

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    23 p.Anthropogenic emissions of greenhouse gases cause climate change and this change in turn induces various direct impacts, e.g., changes in regional weather patterns. The frequency of heat waves and droughts in Europe is likely to rise. Yet, beyond these immediate effects of climate change, there are more indirect effects: Droughts may cause water scarcity and a lack of water supply which in turn would affect further sectors and critical infrastructures. A rising lack of water supply for cooling purposes, for example, will negatively affect electricity generation in power plants. In this paper we analyse such interplays between climate-change affected sectors. We investigate whether and to which extent power generation and supply in Europe is threatened by climate change because of the higher risk of water supply shortages due to more frequent drought and heat-wave incidences. Our proposed approach cannot only be applied to analyse the climate change effects on individual power plant sites or the overall economy but also on electricity exchanges between countries

    Time and tide wait for no man: pioneers and laggards in the deployment of CCS

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    19 p.In Europe the ambitions of individual countries to deploy carbon capture and storage (CCS) technologies are diverse. Reasons for this are, amongst other things, the heterogeneity of national electricity generation systems and storage capacities and the differences in the public perception of these technologies. In this analysis we investigate the consequences of partial deployment of CCS, i.e. we consider a situation where some European countries (the “pioneers”) actively deploy CCS technologies, while others (the “laggards”) do not use CCS. Our study focuses on the question whether it pays throughout to be a pioneer and whether laggards will generally be disadvantaged. In our assessment, we take into account impacts on consumers affected from rising electricity prices, electricity suppliers whose profits are influenced by changes in both electricity prices and sales, and international trade-flow changes (modifications in European electricity import/export patterns)

    Contribution of Shape Memory Alloys Elements in Designing Underwater Smart Structures

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    Shape memory alloys (SMA) have generated a lot of new ideas in engineering. Application is however so far limited to clamps and springs. With respect to smart structures sensing as well as control has to be included. While sensing looks to be relatively feasible control is the big challenge. This paper describes some related a smart structure idea using SMAs and discusses the challenges which need to be solved before these ideas can be realised

    Radiographic cervical spine degenerative findings: a study on a large population from age 18 to 97 years

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    AbstractPurposeThe aims of this study were (1) to determine the prevalence of radiographic cervical disc degeneration in a large population of patients aged from 18 to 97 years; (2) to investigate individually the prevalence and distribution of height loss, osteophyte formation, endplate sclerosis and spondylolisthesis; and (3) to describe the patterns of cervical disc degeneration.MethodsA retrospective study was performed. Standard lateral cervical spine radiographs in standing, neutral position of 1581 consecutive patients (723 males, 858 females) with an average age of 41.2 ± 18.2 years were evaluated. Cervical disc degeneration was graded from C2/C3 to C6/C7 based on a validated quantitative grading system. The prevalence and distribution of radiographic findings were evaluated and associations with age were investigated.Results53.9% of individuals had radiographic disc degeneration and the most affected level was C5/C6. The presence and severity of disc degeneration were found to be significantly associated with age both in male and female subjects. The most frequent and severe occurrences of height loss, osteophyte formation, and endplate sclerosis were at C5/C6, whereas spondylolisthesis was most observed at C4/C5. Age was significantly correlated with radiographic degenerative findings. Contiguous levels degeneration pattern was more likely found than skipped level degeneration. The number of degenerated levels was also associated with age.ConclusionsThe presence and severity of radiographic disc degeneration increased with aging in the cervical spine. Older age was associated with greater number of degenerated disc levels. Furthermore, the correlations between age and the degree of degenerative findings were stronger at C5/C6 and C6/C7 than at other cervical spinal levels

    Semi-robotic 6 degree of freedom positioning for intracranial high precision radiotherapy; first phantom and clinical results

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    <p>Abstract</p> <p>Background</p> <p>To introduce a novel method of patient positioning for high precision intracranial radiotherapy.</p> <p>Methods</p> <p>An infrared(IR)-array, reproducibly attached to the patient via a vacuum-mouthpiece(vMP) and connected to the table via a 6 degree-of-freedom(DoF) mechanical arm serves as positioning and fixation system. After IR-based manual prepositioning to rough treatment position and fixation of the mechanical arm, a cone-beam CT(CBCT) is performed. A robotic 6 DoF treatment couch (HexaPOD™) then automatically corrects all remaining translations and rotations. This absolute position of infrared markers at the first fraction acts as reference for the following fractions where patients are manually prepositioned to within ± 2 mm and ± 2° of this IR reference position prior to final HexaPOD-based correction; consequently CBCT imaging is only required once at the first treatment fraction.</p> <p>The preclinical feasibility and attainable repositioning accuracy of this method was evaluated on a phantom and human volunteers as was the clinical efficacy on 7 pilot study patients.</p> <p>Results</p> <p>Phantom and volunteer manual IR-based prepositioning to within ± 2 mm and ± 2° in 6DoF was possible within a mean(± SD) of 90 ± 31 and 56 ± 22 seconds respectively. Mean phantom translational and rotational precision after 6 DoF corrections by the HexaPOD was 0.2 ± 0.2 mm and 0.7 ± 0.8° respectively. For the actual patient collective, the mean 3D vector for inter-treatment repositioning accuracy (n = 102) was 1.6 ± 0.8 mm while intra-fraction movement (n = 110) was 0.6 ± 0.4 mm.</p> <p>Conclusions</p> <p>This novel semi-automatic 6DoF IR-based system has been shown to compare favourably with existing non-invasive intracranial repeat fixation systems with respect to handling, reproducibility and, more importantly, intra-fraction rigidity. Some advantages are full cranial positioning flexibility for single and fractionated IGRT treatments and possibly increased patient comfort.</p
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