19,395 research outputs found

    “This is the Way I Was”: Urban Ethics, Temporal Logics, and the Politics of Cure

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    This article employs Eli Clare\u27s concept of the politics of cure in order to discuss issues of disability, temporality, and ethical relations to rehabilitation, restoration, and cure in the Sex and the (Motor) City: Ecologies of Middlesex special cluster

    Exploiting evolution to treat drug resistance: Combination therapy and the double bind

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    Although many anti cancer therapies are successful in killing a large percentage of tumour cells when initially administered, the evolutionary dynamics underpinning tumour progression mean that often resistance is an inevitable outcome, allowing for new tumour phenotypes to emerge that are unhindered by the therapy. Research in the field of ecology suggests that an evolutionary double bind could be an effective way to treat tumours. In an evolutionary double bind two therapies are used in combination such that evolving resistance to one leaves individuals more susceptible to the other. In this paper we present a general evolutionary game theory model of a double bind to study the effect that such approach would have in cancer. Furthermore we use this mathematical framework to understand recent experimental results that suggest a synergistic effect between a p53 cancer vaccine and chemotherapy. Our model recapitulates the experimental data and provides an explanation for its effectiveness based on the commensalistic relationship between the tumour phenotypes

    The impact of cellular characteristics on the evolution of shape homeostasis

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    The importance of individual cells in a developing multicellular organism is well known but precisely how the individual cellular characteristics of those cells collectively drive the emergence of robust, homeostatic structures is less well understood. For example cell communication via a diffusible factor allows for information to travel across large distances within the population, and cell polarisation makes it possible to form structures with a particular orientation, but how do these processes interact to produce a more robust and regulated structure? In this study we investigate the ability of cells with different cellular characteristics to grow and maintain homeostatic structures. We do this in the context of an individual-based model where cell behaviour is driven by an intra-cellular network that determines the cell phenotype. More precisely, we investigated evolution with 96 different permutations of our model, where cell motility, cell death, long-range growth factor (LGF), short-range growth factor (SGF) and cell polarisation were either present or absent. The results show that LGF has the largest positive impact on the fitness of the evolved solutions. SGF and polarisation also contribute, but all other capabilities essentially increase the search space, effectively making it more difficult to achieve a solution. By perturbing the evolved solutions, we found that they are highly robust to both mutations and wounding. In addition, we observed that by evolving solutions in more unstable environments they produce structures that were more robust and adaptive. In conclusion, our results suggest that robust collective behaviour is most likely to evolve when cells are endowed with long range communication, cell polarisation, and selection pressure from an unstable environment

    Nitrogen Gas Generation and Diffusion from Diazo Reproducution Materials

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    It has been hypothesised that generation of nitrogen during exposure by diazo duplication materials can contribute to image degradations in microform and aerial negative reproductions. Research was conducted to investigate the rate generated gas is diffused from the surface and possible film- film separations this gas may cause during contact printing. Apparatus was constructed to measure gas diffusion rates and simulated film-film separations during exposure. Diffused gas was collected in a rubber diaphragm whose expansion was measured using a variable capacitor tuned oscillator technique. To simulate printer film- film separations movement of a 5.4 x 7.5 cm. glass plate placed on the film was measured during exposure. A metal-halide mercury vapor lamp and optical system in the apparatus projected sufficient energy to destroy one half the potential density in 2.4 to 5,7 seconds. This time depended upon the type of film -10 -9 used. Measured gas diffusion rates ranged from 3.3 x 10 to 9.2 x 10 mole/sq cm/sec for the four positive working diazo films evaluated. Platefilm separations up to 2. 2- urn were measured. It was also determined that gas release is not instantaneous upon exposure and that gas continues to be diffused after exposure has terminated. In addition exposures from the top and bottom of the emulsion produce different initial gas release rates. Analytical models were developed to correlate experimental data with printer film- film separations. Measured plate-film separations were less than predicted by the models. It is believed that the models are correct and that during the plate- film separation experiments the film had an initial curl, thus violating the parallel initial zero separation condition and explaining the differences

    Pedagogy of Community Organizing: Lessons Learned from and With Formal Educators, Professional Trainers, and Community Organizers

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    Most, if not all, large-scale changes in social, economic, and civic policy in modern times resulted not from small adjustments within administrative institutions but from social movements built through decades of organizing. For community organizing to fulfill its traditional role in social movements, there must be well-trained organizers. The questions pursued in this research are: how is organizing being taught both in community-based and academic settings, what is being taught including the core concepts, skills, and competencies, and what and how should it be taught in the future? Two different spheres of practice have historically served to unite, educate, and activate people in the exercise of community organizing: community-based institutions; and scholarly-educational disciplines. My research used two theoretical frameworks to explore the process of teaching and learning organizing as well as bridging these two spheres: critical pedagogy; and social movement theory. My research was mixed methods with both quantitative and qualitative elements: a meta-analysis of literature related to community organizing education and knowledge production; a survey of organizers in the Twin Cities metropolitan area; and interviews with formal, non-formal, and informal educators, specifically academics, professional trainers, and veteran organizers. The three basic components I examined in developing a community organizing pedagogy were: (1) the learning objectives of community organizers, as identified by the learners themselves: (2) the curriculum, using experienced community organizers as the source of this knowledge production; and (3) the teaching methodology, drawing on methods from both community organizing practice as well as educational and scholarly practice. My research followed two methodological traditions: phenomenology; and grounded theory. I used phenomenology to understand how the educators’ lived experience influenced them as practitioners and educators, including decisions about curriculum and teaching methods, and to produce a set of educational recommendations. I used grounded theory to understand who is organizing in the Twin Cities and the amount, quality, and impact of their education, and to produce of a model for organizing pedagogy describing the educational settings, sources, and methods. Finally, I identified possible future research, including field observations of current education programs and a pilot program of my proposed pedagogy

    A mathematical model of tumor self-seeding reveals secondary metastatic deposits as drivers of primary tumor growth

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    Two models of circulating tumor cell (CTC) dynamics have been proposed to explain the phenomenon of tumor 'self-seeding', whereby CTCs repopulate the primary tumor and accelerate growth: Primary Seeding, where cells from a primary tumor shed into the vasculature and return back to the primary themselves; and Secondary Seeding, where cells from the primary first metastasize in a secondary tissue and form microscopic secondary deposits, which then shed cells into the vasculature returning to the primary. These two models are difficult to distinguish experimentally, yet the differences between them is of great importance to both our understanding of the metastatic process and also for designing methods of intervention. Therefore we developed a mathematical model to test the relative likelihood of these two phenomena in the subset of tumours whose shed CTCs first encounter the lung capillary bed, and show that Secondary Seeding is several orders of magnitude more likely than Primary seeding. We suggest how this difference could affect tumour evolution, progression and therapy, and propose several possible methods of experimental validation.Comment: 20 pages, 4 figure
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