225 research outputs found

    Predictability in an unpredictable artificial cultural market

    Full text link
    In social, economic and cultural situations in which the decisions of individuals are influenced directly by the decisions of others, there appears to be an inherently high level of ex ante unpredictability. In cultural markets such as films, songs and books, well-informed experts routinely make predictions which turn out to be incorrect. We examine the extent to which the existence of social influence may, somewhat paradoxically, increase the extent to which winners can be identified at a very early stage in the process. Once the process of choice has begun, only a very small number of decisions may be necessary to give a reasonable prospect of being able to identify the eventual winner. We illustrate this by an analysis of the music download experiments of Salganik et.al. (2006). We derive a rule for early identification of the eventual winner. Although not perfect, it gives considerable practical success. We validate the rule by applying it to similar data not used in the process of constructing the rule

    Incorporating Concepts of Nanotechnology into the Materials Science and Engineering Classroom and Laboratory

    Get PDF
    The National Science Foundation-supported Materials Research Science and Engineering Center (MRSEC) on Nanostructured Materials and Interfaces at the University of Wisconsin – Madison has an extensive and highly successful education and outreach effort. One theme of this effort is the development of instructional materials based on cutting-edge research in nanoscale science and engineering. Nanotechnology examples, such as light emitting diodes (LEDs), shape memory alloys, amorphous metals, and ferrofluids, illustrate interdisciplinary research that provides connections among materials science, chemistry, physics, and engineering. They also highlight the tools of nanotechnology, such as scanning probe microscopy, electron microscopy, self-assembly, x-ray diffraction, and chemical vapor deposition, associated with the preparation and characterization of nanostructured materials. These and other nanotechnology concepts are illustrated with video demonstrations in a web-based resource called the Nanoworld Cineplex, which contains movies of experiments and demonstrations that can be brought into the classroom. Numerous experiments are also available in the Nanotechnology Lab Manual, which can be used as either a virtual laboratory or as a web-based video lab manual. These resources for using nanotechnology to teach fundamental materials science and engineering principles are available at

    Gasping in Response to Basic Resuscitation Efforts: Observation in a Swine Model of Cardiac Arrest

    Get PDF
    Objective. To analyze the effect of basic resuscitation efforts on gasping and of gasping on survival. Methods. This is secondary analysis of a previously reported study comparing continuous chest compressions (CCC CPR) versus chest compressions plus ventilation (30:2 CPR) on survival. 64 swine were randomized to 1 of these 2 basic CPR approaches after either short (3 or 4 minutes) or long (5 or 6 minutes) durations of untreated VF. At 12 minutes of VF, all received the same Guidelines 2005 Advanced Cardiac Life Support. Neurologically status was evaluated at 24 hours. A score of 1 is normal, 2 is abnormal, such as not eating or drinking normally, unsteady gait, or slight resistance to restraint, 3 severely abnormal, where the animal is recumbent and unable to stand, 4 is comatose, and 5 is dead. For this analysis a neurological outcome score of 1 or 2 was classified as “good”, and a score of 3, 4, or 5 was classified as “poor.” Results. Gasping was more likely to continue or if absent, to resume in the animals with short durations of untreated VF before basic resuscitation efforts. With long durations of untreated VF, the frequency of gasping and survival was better in swine receiving CCC CPR. In the absence of frequent gasping, intact survival was rare in the long duration of untreated VF group. Conclusions. Gasping is an important phenomenon during basic resuscitation efforts for VF arrest and in this model was more frequent with CCC-CPR

    Political strategies of external support for democratization

    Get PDF
    Political strategies of external support to democratization are contrasted and critically examined in respect of the United States and European Union. The analysis begins by defining its terms of reference and addresses the question of what it means to have a strategy. The account briefly notes the goals lying behind democratization support and their relationship with the wider foreign policy process, before considering what a successful strategy would look like and how that relates to the selection of candidates. The literature's attempts to identify strategy and its recommendations for better strategies are compared and assessed. Overall, the article argues that the question of political strategies of external support for democratization raises several distinct but related issues including the who?, what?, why?, and how? On one level, strategic choices can be expected to echo the comparative advantage of the "supporter." On a different level, the strategies cannot be divorced from the larger foreign policy framework. While it is correct to say that any sound strategy for support should be grounded in a theoretical understanding of democratization, the literature on strategies reveals something even more fundamental: divergent views about the nature of politics itself. The recommendations there certainly pinpoint weaknesses in the actual strategies of the United States and Europe but they have their own limitations too. In particular, in a world of increasing multi-level governance strategies for supporting democratization should go beyond preoccupation with just an "outside-in" approach

    Preparation of amino-substituted indenes and 1,4-dihydronaphthalenes using a one-pot multireaction approach: total synthesis of oxybenzo[c]phenanthridine alkaloids

    Get PDF
    Allylic trichloroacetimidates bearing a 2-vinyl or 2-allylaryl group have been designed as substrates for a one-pot, two-step multi-bond-forming process leading to the general preparation of aminoindenes and amino-substituted 1,4-dihydronaphthalenes. The synthetic utility of the privileged structures formed from this one-pot process was demonstrated with the total synthesis of four oxybenzo[c]phenanthridine alkaloids, oxychelerythrine, oxysanguinarine, oxynitidine, and oxyavicine. An intramolecular biaryl Heck coupling reaction, catalyzed using the Hermann–Beller palladacycle was used to effect the key step during the synthesis of the natural products

    Biomorpher: interactive evolution for parametric design

    Get PDF
    Combining graph-based parametric design with metaheuristic solvers has to date focussed solely on performance based criteria and solving clearly defined objectives. In this paper, we outline a new method for combining a parametric modelling environment with an interactive Cluster-Orientated Genetic Algorithm (COGA). In addition to performance criteria, evolutionary design exploration can be guided through choice alone, with user motivation that cannot be easily defined. As well as numeric parameters forming a genotype, the evolution of whole parametric definitions is discussed through the use of genetic programming. Visualisation techniques that enable mixing small populations for interactive evolution with large populations for performance-based optimisation are discussed, with examples from both academia and industry showing a wide range of applications

    Education for citizenship in South Australian public schools: a pilot study of senior leader and teacher perceptions

    Get PDF
    Preparing students for informed and active citizenship is a core goal of education and schooling in Australia. The ways schools educate and prepare young Australians for citizenship involves a range of processes and initiatives central to the work of schools, including school ethos, mission, extra-curricular activities and community-based participation. With regard to the formal curriculum, the recent introduction and implementation of the first ever Federal Australian curriculum includes provision for a new subject – Civics and Citizenship. Research evidence from other nations suggests that schools understand, approach and enact education for citizenship in a multitude of ways, yet how Australian schools construct this aspect of their work is currently under-researched. In this context, and drawing on data from interviews with school leaders and teachers of year six-eight (11-14 year olds) students in a small sample of South Australian primary and secondary schools, we explore perceptions and current approaches to education for citizenship. Our findings suggest (i) that while school leaders and teachers value education for citizenship, they do so for different reasons; (ii) that schools place values as central to education for citizenship; and, (iii) that community involvement is typically understood as occurring within rather than beyond the school
    • …
    corecore