Preferences show greater stability for transactions than for gambles in cost discounting

Many factors point to the underlying instability of preferences in choice behavior. In particular, discounting reveals some effects not consistent with stable preferences. In discounting, the subjective value of a reward reduces as the uncertainty of or delay to obtaining it increases. The function relating subjective value to delay or probability must be exponential with a constant discount rate to respect transitivity over time, i.e., if A > B and B > C, then A > C (“ > ” = is preferred to). If the discount rate varies with value or time, then it is possible for transitivity to be violated, i.e., for preferences to be unstable. And people do show unstable, preference reversals over time in intertemporal choice more consistent with a hyperbolic discounting function (e.g., Myerson and Green, 1995). Thus, while someone may prefer £100 for certain now rather than £110 tomorrow, they will prefer £110 in a year and a day over £100 in a year’s time. People discount rate is very high initially, more rapid than the exponential, but over time it decreases leading to a flatter function than the exponential. Consequently, the £10 difference is almost totally discounted in the short term, but in a year’s time the extra day barely reduces the subjective value we attach to gaining an extra £10

Can a simple measure of vigorous physical activity predict future mortality? Results from the OXCHECK study.

BACKGROUND: As epidemiological studies have become more complex, demands for short, easily administered measures of risk factors have increased. This study investigates whether such a measure of physical activity is associated with the risk of death from all causes and death from specific causes. METHODS: A prospective follow-up study of 11,090 men and women, aged 35-64 years, recruited from five UK general practices who responded to a postal questionnaire in 1989. Self-reported frequency of vigorous-intensity physical activity and data on confounding factors were collected at baseline survey. Death notifications up to 31 December 2001 were provided by the Office for National Statistics. The relative risk (and 95% confidence interval) of dying associated with each level of exposure to physical activity was estimated by the hazard ratio in a series of Cox regression models. RESULTS: After >10 years' follow-up there were 825 deaths among the 10 522 subjects with no previous history of angina or myocardial infarction. Participation in vigorous exercise was associated with a significantly lower risk of all-cause mortality. Similar associations were found for ischaemic heart disease and cancer mortality, although the relationships were not significant at the 5% level. CONCLUSIONS: Simple measures of self-reported vigorous physical activity are associated with the risk of future mortality, at least all-cause mortality in a somewhat selected group. Interpretation of the finding should be treated with caution due to the reliance on self-report and the possibility that residual confounding may underlie the associations. Because moderate-intensity physical activity is also beneficial to health, short physical activity questionnaires should include measures of such physical activity in the future

A Wideband, Four-Element, All-Digital Beamforming System for Dense Aperture Arrays in Radio Astronomy

Densely-packed, all-digital aperture arrays form a key area of technology development required for the Square Kilometre Array (SKA) radio telescope. The design of real-time signal processing systems for digital aperture arrays is currently a central challenge in pathfinder projects worldwide. We describe interim results of such work; an heirarchical, frequency-domain beamforming architecture for synthesising a sky beam from the wideband antenna feeds of digital aperture arrays.Comment: 4 pages, 6 figure

Automated Classification of Stellar Spectra. II: Two-Dimensional Classification with Neural Networks and Principal Components Analysis

We investigate the application of neural networks to the automation of MK spectral classification. The data set for this project consists of a set of over 5000 optical (3800-5200 AA) spectra obtained from objective prism plates from the Michigan Spectral Survey. These spectra, along with their two-dimensional MK classifications listed in the Michigan Henry Draper Catalogue, were used to develop supervised neural network classifiers. We show that neural networks can give accurate spectral type classifications (sig_68 = 0.82 subtypes, sig_rms = 1.09 subtypes) across the full range of spectral types present in the data set (B2-M7). We show also that the networks yield correct luminosity classes for over 95% of both dwarfs and giants with a high degree of confidence. Stellar spectra generally contain a large amount of redundant information. We investigate the application of Principal Components Analysis (PCA) to the optimal compression of spectra. We show that PCA can compress the spectra by a factor of over 30 while retaining essentially all of the useful information in the data set. Furthermore, it is shown that this compression optimally removes noise and can be used to identify unusual spectra.Comment: To appear in MNRAS. 15 pages, 17 figures, 7 tables. 2 large figures (nos. 4 and 15) are supplied as separate GIF files. The complete paper can be obtained as a single gziped PS file from http://wol.ra.phy.cam.ac.uk/calj/p1.htm

Is what you see what you get? representations, metaphors and tools in mathematics didactics

This paper is exploratory in character. The aim is to investigate ways in which it is possible to use the theoretical concepts of representations, tools and metaphors to try to understand what learners of mathematics ‘see’ during classroom interactions (in their widest sense) and what they might get from such interactions. Through an analysis of a brief classroom episode, the suggestion is made that what learners see may not be the same as what they get. From each of several theoretical perspectives utilised in this paper, what learners ‘get’ appears to be something extra. According to our analysis, this something ‘extra’ is likely to depend on the form of technology being used and the representations and metaphors that are available to both teacher and learner

Mensaje del presidente para la edición inaugural del ISAK Journal

oai:ojs2.ijok.org:article/3It is with both pleasure and pride that ISAK announces the first edition of the International Journal of Kinanthropometry which will showcase research in the area of Anthropometry and its applications. Other than in this first issue, where contributions have been by invitation and evaluated for acceptability by the editorial team, the journal will only publish refereed scientific papers plus research reviews and case studies. You will see that we have an interesting selection of papers for you to read and I thank all contributors for both their research and their willingness to share it with us. The journal marks yet another significant milestone in ISAK’s development and will stand or fall on both the quantity and quality of papers submitted. Although we anticipate that the majority of papers submitted will come from ISAK members, it is not a requirement that submitters and/or co-authors be members of ISAK. Our sincere gratitude for this production goes to the Journal’s Editor-in-Chief, Dr Anup Adhikari and the publication team led by Dr Babu Balraj from IOR Press.Es un placer y un orgullo que ISAK anuncia la primera edición de la Revista Internacional de Cineantropometría, que mostrará la investigación en el área de la antropometría y sus aplicaciones. Aparte de este primer número, donde las contribuciones han sido por invitación y evaluadas para su aceptabilidad por parte del equipo editorial, la revista solo publicará artículos científicos arbitrados más revisiones de investigación y estudios de casos. Verá que tenemos una interesante selección de artículos para que los lea y agradezco a todos los colaboradores tanto por su investigación como por su disposición a compartirla con nosotros. La revista marca otro hito importante en el desarrollo de ISAK y se mantendrá o caerá tanto en la cantidad como en la calidad de los artículos presentados. Aunque anticipamos que la mayoría de los trabajos presentados provendrán de miembros de ISAK, no es un requisito que los remitentes y / o coautores sean miembros de ISAK. Nuestro más sincero agradecimiento por esta producción va para el editor en jefe de la revista, el Dr. Anup Adhikari y el equipo de publicación dirigido por el Dr. Babu Balraj de IOR Press