1,030 research outputs found
Reviewing the Author-Function in the Age of Wikipedia
No full textIn Reviewing the Author-Function in the Age of Wikipedia, Amit Ray and Erhardt Graeff examine how wiki technology challenges traditional concepts of authorship and authority in knowledge production. The authors build on poststructuralist theory, particularly Roland Barthes\u27s Death of the Author and Michel Foucault\u27s concept of the author-function, to analyze how wikis destabilize individual authorship in favor of collaborative, community-driven content creation.
The essay argues that wikis represent a fundamental shift from the Romantic notion of the solitary author-genius to what they term the wiki writing process —a dynamic system where traditional roles of reader, writer, and editor blur into a unified community of users. Using Wikipedia as a primary case study, the authors demonstrate how the platform\u27s structure (article, discussion, and history pages) creates a digital palimpsest that archives all contributions while enabling continuous revision.
Through analysis of Wikipedia\u27s editing patterns and community oversight mechanisms, Ray and Graeff show how wikis embody poststructuralist principles in practice, creating what they call serial collaborations that exist in perpetual flux. The authors conclude that wikis represent an evolved form of textual production that realizes Foucault\u27s vision of discourse freed from traditional authorial constraints, offering new possibilities for collaborative knowledge creation while challenging established notions of intellectual authority and ownership
Augustin Graeff - Dam Designer and Hydraulic Engineer
No full textDams have been erected from the earliest times in China and the
Near East, and later in Spain. Until around 1850, dam heights
were extremely limited because no computational models were
available for engineering design. Perhaps more important, the
population downstream often opposed these structures because it
had often experienced dam failures resulting in significant loss of
life and property. Embankment dams reached a maximum height
of some 20 m, whereas gravity dams had a maximum height of
some 30 m *Schnitter 1994*. In the 1860s, the design of gravity
dams was developed mainly by French engineers, one of which
was Auguste Graeff *Fig. 1, Fig. 2*. The following traces his
career and gives an overview in the advances made in hydraulic
engineering during the second half of the 19th century
The Rationale for Consuming Cognitive Enhancement Drugs in University Students and Teachers
No full textSattler S, Sauer C, Mehlkop G, Graeff P. The Rationale for Consuming Cognitive Enhancement Drugs in University Students and Teachers. PLoS ONE. 2013;8(7): e68821.Cognitive enhancement (CE) is the pharmaceutical augmentation of mental abilities (e.g., learning or memory) without medical necessity. This topic has recently attracted widespread attention in scientific and social circles. However, knowledge regarding the mechanisms that underlie the decision to use CE medication is limited. To analyze these decisions, we used data from two online surveys of randomly sampled university teachers (N = 1,406) and students (N = 3,486). Each respondent evaluated one randomly selected vignette with regard to a hypothetical CE drug. We experimentally varied the characteristics of the drugs among vignettes and distributed them among respondents. In addition, the respondent’s internalization of social norms with respect to CE drug use was measured. Our results revealed that students were more willing to enhance cognitive performance via drugs than university teachers, although the overall willingness was low. The probability of side effects and their strength reduced the willingness to use CE drugs among students and university teachers, whereas higher likelihoods and magnitudes of CE increased this propensity. In addition, the internalized norm against CE drug use influenced decision making: Higher internalization decreased the willingness to use such medications. Students’ internalized norms more strongly affected CE abstinence compared with those of university teachers. Furthermore, internalized norms negatively interacted with the instrumental incentives for taking CE medication. This internalization limited the influence of and deliberation on instrumental incentives. This study is the first to provide empirical evidence regarding the importance of social norms and their influence on rational decision making with regard to CE. We identified previously undiscovered decision-making patterns concerning CE. Thus, this study provides insight into the motivators and inhibitors of CE drug use. These findings have implications for contending with CE behavior by highlighting the magnitude of potential side effects and by informing the debate regarding the ethics of CE use
A Modular System for Treating Moving Anatomical Targets With Scanned Ion Beams at Multiple Facilities: Pre-Clinical Testing for Quality and Safety of Beam Delivery
No full textBackground: Quality management and safety are integral to modern radiotherapy. New radiotherapy technologies require new consensus guidelines on quality and safety. Established analysis strategies, such as the failure modes and effects analysis (FMEA) and incident learning systems have been developed as tools to assess the safety of several types of radiation therapies. An extensive literature documents the widespread application of risk analysis methods to photon radiation therapy. Relatively little attention has been paid to performing risk analyses of nascent radiation therapy systems to treat moving tumors with scanned heavy ion beams. The purpose of this study was to apply a comprehensive safety analysis strategy to a motion-synchronized dose delivery system (M-DDS) for ion therapy. Methods: We applied a risk analysis method to new treatment planning and treatment delivery processes with scanned heavy ion beams. The processes utilize a prototype, modular dose delivery system, currently undergoing preclinical testing, that provides new capabilities for treating moving anatomy. Each step in the treatment process was listed in a process map, potential errors for each step were identified and scored using the risk probability number in an FMEA, and the possible causes of each error were described in a fault tree analysis. Solutions were identified to mitigate the risk of these errors, including permanent corrective actions, periodic quality assurance (QA) tests, and patient specific QA (PSQA) tests. Each solution was tested experimentally. Results: The analysis revealed 58 potential errors that could compromise beam delivery quality or safety. Each of the 14 binary (pass-or-fail) tests passed. Each of the nine QA and four PSQA tests were within anticipated clinical specifications. The modular M-DDS was modified accordingly, and was found to function at two centers. Conclusion: We have applied a comprehensive risk analysis strategy to the M-DDS and shown that it is a clinically viable motion mitigation strategy. The described strategy can be utilized at any ion therapy center that operates with the modular M-DDS. The approach can also be adapted for use at other facilities and can be combined with existing safety analysis systems
Placing Value in Domestic Interiors:3D Spatial Mapping of Pieter de Graeff and Jacoba Bicker’s Home Art Collection
No full textThis article explores the interplay between place and value in the display of art in domestic spaces in seventeenth-century Amsterdam, using the painting collection of Pieter de Graeff (1638-1707) and Jacoba Bicker (1640-1695) as a case study. With the aid of a schematic 3D reconstruction of their house, based on De Graeff’s inventory and other sources, this research brings these artworks back to their original domestic context, testing hypotheses regarding their placement and visual impact while investigating display patterns. The 3D spatial mapping of De Graeff’s inventory connects the paintings’ monetary values with their location, and helps evaluate the symbolic and emotional values attributed to family portraits and other artworks. The article is accompanied by a methodological section in the HTML format detailing the 3D reconstruction process and sources
WE-G-213CD-01: 4D Optimization for Scanned Ion Beam Tracking Therapy for Moving Tumors
No full textPurpose: To apply scanned ion radiotherapy to patients with moving tumors, motion mitigation approaches are needed. The purpose of the current study was to determine whether 4D optimized ion beam tracking therapy could reduce dose to critical structures near a moving target while maintaining target dose coverage. Methods: A conjugate gradient minimization algorithm was developed to incorporate 4D organ motion data in the optimization of scanned ion pencil beam fluences. Treatment plans for 3D and 4D optimized carbon beam tracking were prepared using an in‐ house code for a sphere target volume moving in water with a proximal avoidance volume. For 1 lung cancer patient, 3D and 4D optimized carbon beam tracking treatment plans were designed to provide uniform dose coverage to a clinical target volume and minimal dose to the heart. For both the water phantom and patient case, 4D dose distributions were calculated. Differences between 3D and 4D optimized beam tracking were analyzed using dose colorplanes, dose‐volume histograms, and dose‐volume statistics. Results: For the sphere target, 3D optimized beam tracking achieved target dose coverage of (100.0 ± 0.3)% and a mean and maximum avoidance volume dose of 26.1% and 89.4%, respectively. 4D optimized beam tracking achieved target dose coverage of (99.9 ± 0.4)% and a mean and maximum avoidance volume dose of 7.7% and 42.2%, respectively. For the lung patient, 3D optimized beam tracking achieved target dose coverage of (101.0 ± 5.9)% and a mean and maximum heart dose of 7.7%and 103.4%, respectively. 4D optimized beam tracking achieved target dose coverage of (100.0 ± 0.1)% and a mean and maximum heart dose of 8.7% and 100.3%, respectively. Conclusions: 4D optimized ion beam tracking therapy may be used to reduce the maximum dose to critical structures near a moving target, compared to 3D optimized ion beam tracking therapy. Work supported by the Rosalie B. Hite Fellowship, The University of Texas M. D. Anderson Cancer Center, Houston, Texas. © 2012, American Association of Physicists in Medicine. All rights reserved
The ErbB signalling pathway: protein expression and prognostic value in epithelial ovarian cancer
No full textOvarian cancer is the most frequent cause of death from gynaecological cancer in the Western world. Current prognostic factors do not allow reliable prediction of response to chemotherapy and survival for individual ovarian cancer patients. Epidermal growth factor receptor (EGFR) and HER-2/neu are frequently expressed in ovarian cancer but their prognostic value remains unclear. In this study, we investigated the expression and prognostic value of EGFR, EGFR variant III (EGFRvIII), HER-2/neu and important downstream signalling components in a large series of epithelial ovarian cancer patients. Immunohistochemical staining of EGFR, pEGFR, EGFRvIII, Her-2/neu, PTEN (phosphatase and tensin homologue deleted on chromosome 10), total and phosphorylated AKT (pAKT) and phosphorylated ERK (pERK) was performed in 232 primary tumours using the tissue microarray platform and related to clinicopathological characteristics and survival. In addition, EGFRvIII expression was determined in 45 tumours by RT–PCR. Our results show that negative PTEN immunostaining was associated with stage I/II disease (P=0.006), non-serous tumour type (P=0.042) and in multivariate analysis with a longer progression-free survival (P=0.015). Negative PTEN staining also predicted improved progression-free survival in patients with grade III or undifferentiated serous carcinomas (P=0.011). Positive pAKT staining was associated with advanced-stage disease (P=0.006). Other proteins were expressed only at low levels, and were not associated with any clinicopathological parameter or survival. None of the tumours were positive for EGFRvIII. In conclusion, our results indicate that tumours showing negative PTEN staining could represent a subgroup of ovarian carcinomas with a relatively favourable prognosis
Modest effect of p53, EGFR and HER-2/neu on prognosis in epithelial ovarian cancer: a meta-analysis
No full textBackground: P53, egfr and her-2/neu are the most frequently studied molecular biological parameters in epithelial ovarian cancer, but their prognostic impact is still unequivocal. We performed a meta-analysis to more precisely estimate their prognostic significance. Methods: Published studies that investigated the association between p53, egfr and her-2/neu status and survival were identified. Meta-analysis was performed using a dersimonian-laird model. Publication bias was investigated using funnel plots and sources of heterogeneity were identified using meta-regression analysis. Results: A total of 62 studies were included for p53, 15 for egfr and 20 for her-2/neu. P53, egfr and her-2/neu status had a modest effect on overall survival (Pooled hr 1.47, 95% Ci 1.33-1.61 For p53; Hr 1.65, 95% Ci 1.25-2.19 For egfr and hr 1.67, 95% Ci 1.34-2.08 For her-2/neu). Meta-regression analysis for p53 showed that figo stage distribution influenced study outcome. For egfr and her-2/neu, considerable publication bias was present. Conclusions: Although p53, egfr and her-2/neu status modestly influences survival, these markers are, by themselves, unlikely to be useful as prognostic markers in clinical practice. Our study highlights the need for well-defined, prospective clinical trials and more complete reporting of results of prognostic factor studies. British journal of cancer ( 2009) 101, 149-159. Doi: 10.1038/Sj.Bjc.6605112 Www.Bjcancer.Com published online 9 june 2009 (C) 2009 Cancer research uk
A modular dose delivery system for treating moving targets with scanned ion beams: Performance and safety characteristics, and preliminary tests
No full textPurpose: The purpose of this study was to develop a modular dose-delivery system (DDS) for scanned-ion radiotherapy that mitigates against organ motion artifacts by synchronizing the motion of the beam with that of the moving anatomy. Methods: We integrated a new motion synchronization system and an existing DDS into two centers. The modular approach to integration utilized an adaptive layer of software and hardware interfaces. The method of synchronization comprised three major tasks, namely, the creation of 3D treatment plans (each representing one phase of respiratory motion and together comprising a 4D plan), monitoring anatomic motion during treatment, and synchronization of the beam to anatomic motion. The synchronization was accomplished in real time by repeatedly selecting and delivering a 3D plan, i.e., the one that most closely corresponded to the current anatomic state, until all plans were delivered. The performance characteristics of the motion mitigation system were tested by delivering 4D treatment plans to a moving phantom and comparing planned and measured dose distributions. Dosimetric performance was considered acceptable when the gamma-index pass rate was >90%, homogeneity-index value was >95%, and conformity-index value was >60%. Selected safety characteristics were tested by introducing errors during treatment and testing DDS response. Results: Acceptable dosimetric performance and safety characteristics were observed for all treatment plans. Conclusions: We demonstrated, for the first time, that a modular prototype system, synchronizing scanned ion beams with moving targets can deliver conformal, motion-compensated dose distributions. The prototype system was implemented and characterized at GSI and CNAO
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