Combinatorial Games with a Pass: A dynamical systems approach

By treating combinatorial games as dynamical systems, we are able to address a longstanding open question in combinatorial game theory, namely, how the introduction of a "pass" move into a game affects its behavior. We consider two well known combinatorial games, 3-pile Nim and 3-row Chomp. In the case of Nim, we observe that the introduction of the pass dramatically alters the game's underlying structure, rendering it considerably more complex, while for Chomp, the pass move is found to have relatively minimal impact. We show how these results can be understood by recasting these games as dynamical systems describable by dynamical recursion relations. From these recursion relations we are able to identify underlying structural connections between these "games with passes" and a recently introduced class of "generic (perturbed) games." This connection, together with a (non-rigorous) numerical stability analysis, allows one to understand and predict the effect of a pass on a game.Comment: 39 pages, 13 figures, published versio

Responses to selection for lean growth in sheep

This paper reports the selection responses achieved, and related results, following 9 years of index selection for lean growth in Suffolk sheep. The breeding goal of the index used comprised carcass lean weight and carcass fat weight at a constant age, with relative economic values of + 3 and –1 per kg. The selection criteria were live weight (LWT), ultrasonic fat depth (UFD) and ultrasonic muscle depth (UMD) adjusted to a constant age of 150 days. By year 9, responses in LWT, UFD and UMD in both sexes, as judged by the divergence between selection and control line performance, amounted to 4·88 kg, –1·1 mm and 2·8 mm respectively; these responses are between 7 and 15% of the overall means of the traits concerned. Although selection was originally on index scores based on phenotypic records, the retrospective analyses reported here used the mixed model applications of residual maximum likelihood to estimate parameters and best linear unbiased prediction to predict breeding values. The statistical model comprised fixed effects plus random effects accounting for direct additive, maternal additive and temporary environmental variation. Estimated genetic trends obtained by regressing estimated breeding values on year of birth were similar to annual responses estimated by comparing selection and control line means. Estimates of direct heritabilities were 0·054, 0·177, 0·286, 0·561 and 0·410 for birth weight (BWT), weaning weight (WWT), LWT, UFD and UMD respectively. Corresponding estimates of maternal heritabilities were 0·287, 0·205, 0·160, 0·083 and 0·164. Phenotypic correlations between all pairs of traits were positive and usually moderately high. There were low negative direct additive correlations between BWT and WWT, and between BWT and LWT, but higher positive maternal additive correlations between all other pairs of weight traits

The ISO LWS high resolution spectral survey towards Sagittarius B2

A full spectral survey was carried out towards the Giant Molecular Cloud complex, Sagittarius B2 (Sgr B2), using the ISO Long Wavelength Spectrometer Fabry-Perot mode. This provided complete wavelength coverage in the range 47-196 um (6.38-1.53 THz) with a spectral resolution of 30-40 km/s. This is an unique dataset covering wavelengths inaccessible from the ground. It is an extremely important region of the spectrum as it contains both the peak of the thermal emission from dust, and crucial spectral lines of key atomic (OI, CII, OIII, NII and NIII) and molecular species (NH3, NH2, NH, H2O, OH, H3O+, CH, CH2, C3, HF and H2D+). In total, 95 spectral lines have been identified and 11 features with absorption depth greater than 3 sigma remain unassigned. Most of the molecular lines are seen in absorption against the strong continuum, whereas the atomic and ionic lines appear in emission (except for absorption in the OI 63 um and CII 158 um lines). Sgr B2 is located close to the Galactic Centre and so many of the features also show a broad absorption profile due to material located along the line of sight. A full description of the survey dataset is given with an overview of each detected species and final line lists for both assigned and unassigned features.Comment: Accepted for publication in MNRA

Spontaneous Polarisation Build up in a Room Temperature Polariton Laser

We observe the build up of strong (~50%) spontaneous vector polarisation in emission from a GaN-based polariton laser excited by short optical pulses at room temperature. The Stokes vector of emitted light changes its orientation randomly from one excitation pulse to another, so that the time-integrated polarisation remains zero. This behaviour is completely different to any previous laser. We interpret this observation in terms of the spontaneous symmetry breaking in a Bose-Einstein condensate of exciton-polaritons

Prevalence and cumulative incidence of food hyper-sensitivity in the first 10 years of life

Background - Prevalence, incidence and natural history of food hypersensitivity (FHS) and its trends in an unselected cohort of older children are unclear.Methods - A birth cohort born on the Isle of Wight (UK) between 2001 and 2002 was followed up prospectively. Children were clinically examined and skin prick tested at set times and invited for food challenges when indicated. At 10 years of age, children were also invited for a blood test.Results - A total of 969 children were recruited at 12 weeks of pregnancy, and 92.9%, 88.5%, 91.6% and 85.3% were assessed at 1, 2, 3 and 10 years. Prevalence of sensitization to any allergen over 10 years was 186 of 969 (19.2%; 95% CI: 16.84–21.8) and 108 of 969 (11.2%; 95% CI: 9.31–13.29) children were sensitized to at least one predefined food allergen. Excluding wheat (due to cross-reactivity with pollen), 40 of 969 (4.1%; 95% CI: 3.19–5.32) children were sensitized to a predefined food allergen. Using food challenges and/or a good clinical history, the cumulative incidence of food hypersensitivity (FHS) in the first decade of life was 64 of 947 (6.8%, 95% CI: 5.2–8.4), while the prevalence of FHS at 10 years was 30 of 827 (3.6%, 95% CI: 2.54–5.15). The vast majority, 25 of 827 (3.0%, 95% CI: 1.8–4.2), suffered from IgE-mediated food allergy, while 5 of 827 (0.6%, 95% CI: 0.07–1.3) had non-IgE-mediated food allergy/food intolerance.Conclusions - By the age of 10 years, 6.8% of children suffered from FHS based on food challenges and a good clinical history. There was a large discrepancy between reported and diagnosed FHS

Changing prevalence of wheeze, rhinitis and allergic sensitisation in late childhood: findings from 2 Isle of Wight birth cohorts’ 12-years apart

Background: While the prevalence of asthma in children is decreasing or remaining the same, time-trends in the prevalence of rhinitis in children are not known. Understanding sensitisation trends may help inform about trends in asthma and rhinitis prevalence.Objective: To assess time -trends of wheeze, rhinitis and aero-allergen sensitisation prevalence at 10 years of age we compared two birth cohorts established 12 years apart. To gain insight into differences in disease prevalence we assessed association of family-history, early life exposures and sensitisation with wheeze and rhinitis in each cohort.Methods: The IoW (Isle-of-Wight) and FAIR (Food-Allergy-and-Intolerance-Research) unselected birth cohorts were established in 1989 and 2001 in IoW. Identical ISAAC questionnaire and Skin Prick test data were collected and compared at 10 years of age.Results: Over the 12 year period from 2001 to 2012, prevalence of lifetime-wheeze, current-wheeze, and those ever-treated-for-asthma decreased by 15.9% (45.5-vs-29.6,p<0.001), 3.9% (18.9-vs-15, p=0.020) and 8.2% (31.7-vs-23.5, p=0.001) respectively. Conversely, current-rhinitis and lifetime-rhinitis prevalence increased by 5.5% (22.6-vs-28.1, p=0.004) and 13% (18.6-vs-31.7, p<0.001) respectively. Atopic status remained stable, however house dust mite (HDM) sensitisation decreased by 5.6% (19.2-vs-13.6, p=0.004) and grass sensitisation increased by 3.5% (12.9-vs-16.4, p=0.054). Male-sex, parental history of asthma and HDM sensitisation were significantly associated with lifetime-wheeze in both cohorts while maternal smoking during pregnancy was a significant risk factor only in the earlier IoW-cohort. Parental history of rhinitis and grass sensitisation were significantly associated with lifetime-rhinitis in both cohorts while HDM sensitisation was significant only for the IoW-cohort.Conclusion: Contrasting changes were noted with falling wheeze and HDM sensitisation but rising rhinitis and grass sensitisation prevalence. Changing prevalence of aero-allergen sensitisations may explain the different time trends observed in these cohorts

Very low prevalence of IgE mediated wheat allergy and high levels of cross-sensitisation between grass and wheat in a UK birth cohort

BackgroundPatients often report adverse reactions to wheat. Interpretation of sensitization to wheat pollen and flour with/without sensitization to grass pollen is a clinical problem.AimWe set out to determine the prevalence of wheat allergy in a birth cohort (10/11 year olds) and investigate the usefulness of performing skin prick tests (SPT), specific IgE tests and component resolved diagnostics to wheat pollen and flour.MethodsThe Food Allergy and Intolerance Research (FAIR) birth cohort included babies born on the Isle of Wight (UK) between September 2001–August 2002 (n = 969). Children were followed up at 1, 2, 3 and 10/11 years. 588 children had SPTs to wheat pollen and grass during the 10 year follow-up. 294 children underwent further SPT to wheat flour and 246 had specific IgE testing to wheat and grass.ResultsEight children underwent oral food challenges (OFC). We diagnosed 0.48 % (4/827; 95 % CI 0–1 %) children with wheat allergy based on OFC. 16.3 % (96/588) were sensitized to grass pollen, 13.4 % (79/588) to wheat pollen; 78 % (75/96) sensitized to both. Only one child was sensitized to wheat flour and wheat pollen, but not grass pollen. For specific IgE, 15.0 % (37/246) and 36.2 % (89/246) were sensitized to wheat and grass pollen, with 40.5 % (36/89) sensitized to both. Of the 37 children sensitized to wheat, 3 (8.1 %) were sensitized to omega 5 gliadin, 1 (2.7 %) to wheat lipid transfer protein and 1 to wheat gliadin.ConclusionClinicians should be aware of the high level of cross-sensitization when performing tests to wheat and grass pollen i.e. sensitisation to wheat specific IgE and wheat pollen SPT should be assessed in the presence of grass pollen SPT and/or specific IgE

Creativity and the computer nerd: an exploration of attitudes

This study arises from our concern that many of our best art and design students are failing to make the most of the opportunities provided by IT because of their fear or dislike of computers. This not only deprives them of useful skills, but, even more importantly, deprives many IT based developments of their input. In this paper we investigate the relationship between attitudes to creativity and to computers among students. We quickly discard an approach based on theories of personality types as philosophically and educationally problematic. An approach based on the self-concept of artists and designers, in relation to their own creativity and to their feelings about computers, offers more hope of progress. This means that we do not try to define the attributes of "creative people". Rather, we ask what creativity means to students of art and design and relate these responses to their attitudes to computers. Self-concept depends on how the subjects see themselves within society and culture, and is liable to change as culture changes. One major instrument of cultural change at the present time is the growth of IT itself. We then describe a first attempt at using a psychological method - Kelly's Repertory Grids - to investigate the self-concept of artists and designers. It is hoped to continue with this approach in further studies over the next few years