208 research outputs found

    Computer memories: the history of computer form

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    This paper looks at the computer as a truly global form. The similar beige boxes found in offices across the world are analysed from the perspective of design history rather than that of the history of science and technology. Through the exploration of an archive of computer manufacturer's catalogues and concurrent design texts, this paper examines the changes that have occurred in the production and consumption of the computer in the context of the workplace, from its inception as a room-sized mainframe operated through a console of flashing lights, to the personal computer as a 'universal' form, reproduced by many manufacturers. It shows how the computer in the past has been as diverse as any other product, and asks how and why it now appears as a standardised, sanitised object. In doing so our relationship with the office computer, past and present is explored, revealing a complex history of vicissitude.</p

    Scale-free memory model for multiagent reinforcement learning. Mean field approximation and rock-paper-scissors dynamics

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    A continuous time model for multiagent systems governed by reinforcement learning with scale-free memory is developed. The agents are assumed to act independently of one another in optimizing their choice of possible actions via trial-and-error search. To gain awareness about the action value the agents accumulate in their memory the rewards obtained from taking a specific action at each moment of time. The contribution of the rewards in the past to the agent current perception of action value is described by an integral operator with a power-law kernel. Finally a fractional differential equation governing the system dynamics is obtained. The agents are considered to interact with one another implicitly via the reward of one agent depending on the choice of the other agents. The pairwise interaction model is adopted to describe this effect. As a specific example of systems with non-transitive interactions, a two agent and three agent systems of the rock-paper-scissors type are analyzed in detail, including the stability analysis and numerical simulation. Scale-free memory is demonstrated to cause complex dynamics of the systems at hand. In particular, it is shown that there can be simultaneously two modes of the system instability undergoing subcritical and supercritical bifurcation, with the latter one exhibiting anomalous oscillations with the amplitude and period growing with time. Besides, the instability onset via this supercritical mode may be regarded as "altruism self-organization". For the three agent system the instability dynamics is found to be rather irregular and can be composed of alternate fragments of oscillations different in their properties.Comment: 17 pages, 7 figur

    Increased 5-HT3-mediated signalling in pelvic afferent neurons from mice deficient in P2X2 and/or P2X3 receptor subunits

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    Extracellular ATP and 5-hydroxytryptamine (5-HT) are both involved in visceral sensory pathways by interacting with P2X and 5-HT3 receptors, respectively. We have investigated the changes in P2X and 5-HT3-mediated signalling in pelvic afferent neurons in mice deficient in P2X2 and/or P2X3 subunits by whole-cell recording of L6ā€“S2 dorsal root ganglion (DRG) neurons and by multi-unit recording of pelvic afferents of the colorectum. In wildtype DRG neurons, ATP evoked transient, sustained or mixed (biphasic) inward currents. Transient currents were absent in P2X3āˆ’/āˆ’ neurons, whereas sustained currents were absent in P2X2āˆ’/āˆ’ DRG neurons. Neither transient nor sustained currents were observed following application of ATP or Ī±,Ī²-methylene ATP (Ī±,Ī²-meATP) in P2X2/P2X3Dblāˆ’/āˆ’ DRG neurons. 5-HT was found to induce a fast inward current in 63% of DRG neurons from wildtype mice, which was blocked by tropisetron, a 5-HT3 receptor antagonist. The percentage of DRG neurons responding to 5-HT was significantly increased in P2X 2āˆ’/āˆ’, P2X3āˆ’/āˆ’ and P2X2/P2X3Dblāˆ’/āˆ’ mice, and the amplitude of 5-HT response was significantly increased in P2X2/P2X3Dblāˆ’/āˆ’ mice. The pelvic afferent response to colorectal distension was attenuated in P2X2/P2X3Dblāˆ’/āˆ’ mice, but the response to serosal application of 5-HT was enhanced. Furthermore, tropisetron resulted in a greater reduction in pelvic afferent responses to colorectal distension in the P2X2/P2X3Dblāˆ’/āˆ’ preparations. These data suggest that P2X receptors containing the P2X2 and/or P2X3 subunits mediate purinergic activation of colorectal afferents and that 5-HT signalling in pelvic afferent neurons is up-regulated in mice lacking P2X2 or P2X3 receptor genes. This effect is more pronounced when both subunits are absent

    The hospital microbiome project: meeting report for the UK science and innovation network UK-USA workshop ā€˜beating the superbugs: hospital microbiome studies for tackling antimicrobial resistanceā€™, October 14th 2013

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    The UK Science and Innovation Network UK-USA workshop ā€˜Beating the Superbugs: Hospital Microbiome Studies for tackling Antimicrobial Resistanceā€™ was held on October 14th 2013 at the UK Department of Health, London. The workshop was designed to promote US-UK collaboration on hospital microbiome studies to add a new facet to our collective understanding of antimicrobial resistance. The assembled researchers debated the importance of the hospital microbial community in transmission of disease and as a reservoir for antimicrobial resistance genes, and discussed methodologies, hypotheses, and priorities. A number of complementary approaches were explored, although the importance of the built environment microbiome in disease transmission was not universally accepted. Current whole genome epidemiological methods are being pioneered in the UK and the benefits of moving to community analysis are not necessarily obvious to the pioneers; however, rapid progress in other areas of microbiology suggest to some researchers that hospital microbiome studies will be exceptionally fruitful even in the short term. Collaborative studies will recombine different strengths to tackle the international problems of antimicrobial resistance and hospital and healthcare associated infections

    ENCODE whole-genome data in the UCSC genome browser (2011 update)

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    The ENCODE project is an international consortium with a goal of cataloguing all the functional elements in the human genome. The ENCODE Data Coordination Center (DCC) at the University of California, Santa Cruz serves as the central repository for ENCODE data. In this role, the DCC offers a collection of high-throughput, genome-wide data generated with technologies such as ChIP-Seq, RNA-Seq, DNA digestion and others. This data helps illuminate transcription factor-binding sites, histone marks, chromatin accessibility, DNA methylation, RNA expression, RNA binding and other cell-state indicators. It includes sequences with quality scores, alignments, signals calculated from the alignments, and in most cases, element or peak calls calculated from the signal data. Each data set is available for visualization and download via the UCSC Genome Browser (http://genome.ucsc.edu/). ENCODE data can also be retrieved using a metadata system that captures the experimental parameters of each assay. The ENCODE web portal at UCSC (http://encodeproject.org/) provides information about the ENCODE data and links for access

    QuantCrit: education, policy, ā€˜Big Dataā€™ and principles for a critical race theory of statistics

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    Quantitative research enjoys heightened esteem among policy-makers, media and the general public. Whereas qualitative research is frequently dismissed as subjective and impressionistic, statistics are often assumed to be objective and factual. We argue that these distinctions are wholly false; quantitative data is no less socially constructed than any other form of research material. The first part of the paper presents a conceptual critique of the field with empirical examples that expose and challenge hidden assumptions that frequently encode racist perspectives beneath the faƧade of supposed quantitative objectivity. The second part of the paper draws on the tenets of Critical Race Theory (CRT) to set out some principles to guide the future use and analysis of quantitative data. These ā€˜QuantCritā€™ ideas concern (1) the centrality of racism as a complex and deeply-rooted aspect of society that is not readily amenable to quantification; (2) numbers are not neutral and should be interrogated for their role in promoting deficit analyses that serve White racial interests; (3) categories are neither ā€˜naturalā€™ nor given and so the units and forms of analysis must be critically evaluated; (4) voice and insight are vital: data cannot ā€˜speak for itselfā€™ and critical analyses should be informed by the experiential knowledge of marginalized groups; (5) statistical analyses have no inherent value but can play a role in struggles for social justice

    A re-examination of the life and work of A.F.G. Kerr and of his colleagues and friends

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    Arthur Francis George Kerrā€™s life is reviewed and related to a previously published account. Kerrā€™s collecting activity is analysed using an expanded version of the Thai Biogeography Groupā€™s database of collections. 8,666 of the total 48,970 collections are Kerrā€™s and 3,178 are those of his colleagues and friends. Therefore, the total number of collections made by Kerr and his acquaintances is likely to be larger and more diverse than previously believed. Mapping of these data using GIS show that Kerrā€™s collecting activities focussed on particular regions of Thailand at particular times. Also large areas of the country remained unexplored by Kerr and his acquaintances: a pattern that, to some extent, persists to this day. The large, but dispersed, archive of Kerrā€™s photographs, maps, living collections and correspondence indicate that he was a skilled photographer (taking at least 3,000 images), cartographer (producing many hand-drawn maps) and exceptionally acute, accurate and detailed observer (filling numerous notebooks and leaving other records). It is clear that digitising these collections to form an on-line dedicated website is highly desirable to further progress on the flora of Thailand and surrounding countries and would form an unique record of the social history of early 20thC Thailand

    The UCSC Genome Browser database: extensions and updates 2011

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    The University of California Santa Cruz Genome Browser (http://genome.ucsc.edu) offers online public access to a growing database of genomic sequence and annotations for a wide variety of organisms. The Browser is an integrated tool set for visualizing, comparing, analyzing and sharing both publicly available and user-generated genomic data sets. In the past year, the local database has been updated with four new species assemblies, and we anticipate another four will be released by the end of 2011. Further, a large number of annotation tracks have been either added, updated by contributors, or remapped to the latest human reference genome. Among these are new phenotype and disease annotations, UCSC genes, and a major dbSNP update, which required new visualization methods. Growing beyond the local database, this year we have introduced ā€˜track data hubsā€™, which allow the Genome Browser to provide access to remotely located sets of annotations. This feature is designed to significantly extend the number and variety of annotation tracks that are publicly available for visualization and analysis from within our site. We have also introduced several usability features including track search and a context-sensitive menu of options available with a right-click anywhere on the Browser's image
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