1,819 research outputs found
More Than 50 Subtypes of Soft Tissue Sarcoma: Paving the Path for Histology-Driven Treatments
No full text Sarcomas are a diverse group of cancers with mesenchymal origin. Although sarcomas comprise less than 1% of cancers, there are more than 50 different subtypes that are quite different from one another in terms of both their biology and clinical behavior. Historically, the need for adequate patient numbers in clinical trials has pushed sarcoma researchers to lump these very different malignancies together and treat the patients using a “one-size-fits-all” approach. However, with improvements in our scientific understanding, we are finally ready for a histology-tailored therapeutic approach to these complex diseases. In this review, we discuss key advances in our understanding of the biology underlying selected sarcoma subtypes and how targeting these subtypes is relevant therapeutically with respect to both molecularly targeted agents as well as immunotherapy. </jats:p
'Comments' on Charles Stephenson's 'Process of Community' and Ronald Foresta's 'Evolution of the Modern Urban Core' - from the 8th NJ History Symposium
No full textThis comments paper by Seth M. Scheiner, an Associate Professor of History at Rutgers University, is from 'New Jersey's Ethnic Heritage: Papers Presented at the Eighth Annual New Jersey History Symposium, December 4, 1976.' Scheiner critiques two research papers from the 8th NJ History Symposium: Charles Stephenson's 'Process of Community' and Ronald Foresta's 'Evolution of the Modern Urban Core.' He also provides additional research related to urban models, demographical statistics, and immigration patterns in New Jersey
Levins and the lure of artificial worlds
No full textWhat is it about simulation models that has led some practitioners to treat them as potential sources of empirical data on the real-world systems being simulated; that is, to treat simulations as ‘artificial worlds’ within which to perform computational ‘experiments’? Here we use the work of Richard Levins as a starting point in identifying the appeal of this model building strategy, and proceed to account for why this appeal is strongest for computational modellers. This analysis suggests a perspective on simulation modelling that makes room for ‘artificial worlds’ as legitimate science without having to accept that they should be treated as sources of empirical dat
The role of logistic constraints on termite construction of chambers and tunnels
No full textIn previous models of the building behaviour of termites, physical and logistic constraints that limit the movement of termites andpheromones have been neglected. Here, we present an individual-based mo del of termite construction that includes idealized constraints on the diffusion of pheromones, the movement of termites, and the integrity of the architecture that they construct. The model allows us to explore the extent to which the results of previous idealized models (typically realised in one or two dimensions via a set of coupled partial differential equations) generalize to a physical, 3-D environment. Moreover we are able to investigate new processes and architectures that rely upon these features. We explore the role of stigmergic recruitment in pillar formation, wall building, and the construction of royal chambers, tunnels and intersections. In addition, for the first time, we demonstrate the way in which the physicality of partially built structures can help termites to achieve efficient tunnel structures and to establish and maintain entrances in royal chambers. As such we show that, in at least some cases, logistic constraints can be important or even necessary in order for termites to achieve efficient, effective constructions
Empiricism in artificial life
No full textStrong artificial life research is often thought to rely on Alife systems as sources of novel empirical data. It is hoped that by augmenting our observations of natural life, this novel data can help settle empirical questions, and thereby separate fundamental properties of living systems from those aspects that are merely contingent on the idiosyncrasies of terrestrial evolution. Some authors have questioned whether this approach can be pursued soundly in the absence of a prior, agreed-upon definition of life. Here we compare Alife’s position to that of more orthodox empirical tools that nevertheless suffer from strong theory-dependence. Drawing on these examples, we consider what kind of justification might be needed to underwrite artificial life as empirical enquir
Combating coevolutionary disengagement by reducing parasite virulence
No full textWhile standard evolutionary algorithms employ a static, absolute fitness metric, coevolutionary algorithms assess individuals by their performance relative to populations of opponents that are themselves evolving. Although this arrangement offers the possibility of avoiding long-standing difficulties such as premature convergence, it suffers from its own unique problems, cycling, over-focusing and disengagement. Here, we introduce a novel technique for dealing with the third and least explored of these problems. Inspired by studies of natural host-parasite systems, we show that disengagement can be avoided by selecting for individuals that exhibit reduced levels of "virulence", rather than maximum ability to defeat coevolutionary adversaries. Experiments in both simple and complex domains are used to explain how this counterintuitive approach may be used to improve the success of coevolutionary algorithms
Wasps, termites and waspmites: Distinguishing competence from performance in collective construction
No full textWe introduce a distinction between algorithm performance and algorithm competence and argue that bio-inpsired computing should characterise the former rather than the latter. To exemplify this, we explore and extend a bio-inspired algorithm for collective construction influenced by paper wasp behaviour. Despite being provably general in its competence we demonstrate limitations on the algorithm's performance. We explain these limitations, and extend the algorithm to include pheromone-mediated behaviour typical of termites. The resulting hybrid "waspmite" algorithm shares the generality of the original wasp algorithm, but exhibits improved performance and scalability
Logistic constraints on 3D termite construction
No full textAbstract. The building behaviour of termites has previously been modelled mathematically in two dimensions. However, physical and logistic constraints were not taken into account in these models. Here, we develop and test a three-dimensional agent-based model of this process that places realistic constraints on the diffusion of pheromones, the movement of termites, and the integrity of the architecture that they construct. The following scenarios are modelled: the use of a pheromone template in the construction of a simple royal chamber, the effect of wind on this process, and the construction of covered pathways. We consider the role of the third dimension and the effect of logistic constraints on termite behaviour and, reciprocally, the structures that they create. For instance, when agents find it difficult to reach some elevated or exterior areas of the growing structure, building proceeds at a reduced rate in these areas, ultimately influencing the range of termite-buildable architectures
The Conversion of Diamond Walnut Growers
No full textThree aspects of property rights theory are particularly relevant to the conversion of the walnut-marketing cooperative, Diamond Walnut Growers (DWG), into a publicly traded stockholder-owned corporation. The horizon problem became apparent when DWG began investing heavily in branded, value-added products. The resulting need for additional member capital raised the free rider problem. The principal-agent problem was also relevant, given the increasing complexity of DWG’s financing and marketing activities. An additional economic issue surrounding the conversion was the monopsonistic situation created when members signed long-term marketing agreements with the new firm that was maximizing shareholder value, rather than grower returns.Agribusiness, Crop Production/Industries,
Caring versus sharing: How to maintain engagement and diversity in coevolving populations
No full textCoevolutionary optimisation suffers from a series of problems that interfere with the progressive escalating arms races that are hoped might solve difficult classes of optimisation problem. Here we explore the extent to which encouraging moderation in one coevolving population (termed parasites) can alleviate the problem of coevolutionary disengagement. Results suggest that, under these conditions, disengagement is avoided through maintaining variation in relative fitness scores. In order to explore whether standard diversity maintenance techniques such as resource sharing could achieve the same effects, we compare moderating virulence with resource sharing in a simple matching game. We demonstrate that moderating parasite virulence differs significantly from resource sharing, and that its tendency to prevent disengagement can also reduce the likelihood of coevolutionary optimisation halting at mediocre stable states.</p
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