527 research outputs found

    Bayesian approach to SETI

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    The search for technosignatures from hypothetical galactic civilizations is going through a new phase of intense activity. For the first time, a significant fraction of the vast search space is expected to be sampled in the foreseeable future, potentially bringing informative data about the abundance of detectable extraterrestrial civilizations, or the lack thereof. Starting from the current state of ignorance about the galactic population of non-natural electromagnetic signals, we formulate a Bayesian statistical model to infer the mean number of radio signals crossing Earth, assuming either non-detection or the detection of signals in future surveys of the Galaxy. Under fairly noninformative priors, we find that not detecting signals within about 11 kly from Earth, while suggesting the lack of galactic emitters or at best the scarcity thereof, is nonetheless still consistent with a probability exceeding 1010 \% that typically over 100\sim 100 signals could be crossing Earth, with radiated power analogous to that of the Arecibo radar, but coming from farther in the Milky Way. The existence in the Galaxy of potentially detectable Arecibo-like emitters can be reasonably ruled out only if all-sky surveys detect no such signals up to a radius of about 4040 kly, an endeavor requiring detector sensitivities thousands times higher than those of current telescopes. Conversely, finding even one Arecibo-like signal within 1000\sim 1000 light years, a possibility within reach of current detectors, implies almost certainly that typically more than 100\sim 100 signals of comparable radiated power cross the Earth, yet to be discovered.Comment: Published in PNAS ahead of print October 1, 2018. Preprint has 13 pages, 7 figures + 7 pages of Supplementary Information with 5 figure

    Preparing potential teachers for the transition from employment to teacher training: an evaluative case study of a Maths Enhancement Course

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    In response to a UK government drive to improve maths teaching in schools, the South West London Maths Enhancement Course (MEC) has been set up though collaboration between three Higher Education institutions (HEIs) to provide an efficient route for non maths graduates in employment to upgrade their subject knowledge and give a smooth transition into teacher training (PGCE). An evaluation of the scheme, measured against Teacher Development Agency (TDA) objectives and success criteria agreed by university staff, involved thematic analysis of focus group discussions and interviews with students and staff during both the MEC and PGCE courses. This has revealed a high level of satisfaction and success related to a number of underlying issues, particularly around student recruitment, curriculum design, peer support and staff collaboration. The model offers an example of practice transferable to a range of programmes aimed at supporting students in the transition between levels and institutions

    A Search for Transient, Monochromatic Light in a 6-deg Swath along the Galactic Plane

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    We searched the Milky Way Plane along a 6-deg swath for pulses of monochromatic light as faint as 15th mag (V band) using a wide-field telescope equipped with a prism. Pulses with duration less than 1 second that occur more often than once every 10 minutes would be detected, and pulses arriving less frequently would be detected with proportionally lower probability. No unexplainable monochromatic emission, pulsed or continuous, was detected. The detection threshold corresponds to a 70 GW laser having a diffraction-limited 10-meter aperture located 1 kiloparsec away (depending on wavelength). Previous searches for laser emission from more than 5000 stars found none. Previous all-sky surveys at optical and radio wavelengths have revealed thousands of unexpected objects in the universe that exhibited extraordinary spectral emission, but none were technological. Hypotheses of our Milky Way Galaxy teeming with advanced life must be demoted.Comment: 22 page

    Integrating multiple clinical information systems using the Java message service framework to enable the delivery of urgent exam results at the point of care

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    The aim of this study is to determine if network-enabled personal digital assistants (PDAs) can be used to facilitate the timely delivery of urgent radiological exam results by reducing the interval from when the radiologist's initial interpretation is available to when it is first viewed by an emergency department (ED) physician. A web- and Java message service (JMS)-based application was built to replace the original fax-based wet-read procedure. The new system allows radiologists to enter wet-reads from the picture archiving and communication system (PACS) display station and to track discrepancies between the wet-read and final report. It also notifies the ED physicians when exam results are available via the PDAs and permits them to view the full text of the wet-read and final reports from the devices. The new system is compared to the original procedure with the results showing improvements with the wireless method. Furthermore, feedback from a qualitative survey of PDA users was positive, suggesting that PDAs may provide one means for accessing urgent clinical data at the point of care

    Increasing Dominance - the Role of Advertising, Pricing and Product Design

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    Despite the empirical relevance of advertising strategies in concentrated markets, the economics literature is largely silent on the effect of persuasive advertising strategies on pricing, market structure and increasing (or decreasing) dominance. In a simple model of persuasive advertising and pricing with differentiated goods, we analyze the interdependencies between ex-ante asymmetries in consumer appeal, advertising and prices. Products with larger initial appeal to consumers will be advertised more heavily but priced at a higher level - that is, advertising and price discounts are strategic substitutes for products with asymmetric initial appeal. We find that the escalating effect of advertising dominates the moderating effect of pricing so that post-competition market shares are more asymmetric than pre-competition differences in consumer appeal. We further find that collusive advertising (but competitive pricing) generates the same market outcomes, and that network effects lead to even more extreme market outcomes, both directly and via the effect on advertising

    Universal Rights and Wrongs

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    This paper argues for the important role of customers as a source of competitive advantage and firm growth, an issue which has been largely neglected in the resource-based view of the firm. It conceptualizes Penrose’s (1959) notion of an ‘inside track’ and illustrates how in-depth knowledge about established customers combines with joint problem-solving activities and the rapid assimilation of new and previously unexploited skills and resources. It is suggested that the inside track represents a distinct and perhaps underestimated way of generating rents and securing long-term growth. This also implies that the sources of sustainable competitive advantage in important respects can be sought in idiosyncratic interfirm relationships rather than within the firm itself

    Advertising, product quality, and complex evolving marketing systems

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    The paper analyses the advertising as power vs. advertising as information controversy as well as its recent empirical testing. It is stressed that this distinction focuses too much on the interaction between consumer and manufacturer while ignoring the retailer as an important stake-holder. To compensate for this lack, a complex marketing system perspective is introduced in which consumer, retailer, and manufacturer interact. However, these complex marketing systems might drift towards market equilibria which are against the consumer interests: that is, firmsmight lock out brands from the market by means of trade and sales promotions and then use advertising to protect their position. Consequently brands of better quality and/or innovative brands are barred from trade shelves
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