359 research outputs found

    Using a Visual Routine to Model the Computation of Positional Relationships

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    Modeling the encoding of visual stimuli is a complex, and often ignored, problem in computational models of visual and spatial problem solving. This paper outlines a toolkit for exploring encoding for two-dimensional visual scenes, Visual Routines for Sketches. The utility of this approach is shown by a new model for computing positional relationships, the Vector Symmetry model, that explains data from seven experiments and is more parsimonious than Regier & Carlson’s (2001) AVS model

    Anticrossings in Foerster Coupled Quantum Dots

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    We consider two coupled generic quantum dots, each modelled by a simple potential which allows the derivation of an analytical expression for the inter-dot Foerster coupling, in the dipole-dipole approximation. We investigate the energy level behaviour of this coupled two-dot system under the influence of an external applied electric field and predict the presence of anticrossings in the optical spectra due to the Foerster interaction.Comment: 13 pages, 7 figures. Published version. Substantially revised, new sections on decay rates, absorption spectra, and tunnelin

    Creating excitonic entanglement in quantum dots through the optical Stark effect

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    We show that two initially non-resonant quantum dots may be brought into resonance by the application of a single detuned laser. This allows for control of the inter-dot interactions and the generation of highly entangled excitonic states on the picosecond timescale. Along with arbitrary single qubit manipulations, this system would be sufficient for the demonstration of a prototype excitonic quantum computer.Comment: 4 pages, 3 figures; published version, figure 3 improved, corrections to RWA derive

    Using word clouds to present farmers’ perceptions of advisory services on pollution mitigation measures

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    Advice delivery is one mechanism that can be used to encourage the uptake of water pollution mitigation measures amongst the farming community, but determining who is best placed to effectively provide advice and increase adoption creates a challenge for policy makers. Through in-depth interviews, this research investigates the perspectives of both farmers and farm advisers on the delivery of water pollution mitigation advice in three agriculturally contrasting areas of England. A novel approach using word clouds as a visual comparative tool for qualitative data is presented to demonstrate a transferable method for disseminating research findings to a wider audience outside of academia. Results from the interviews indicate differences across the regions, and that contrasts exist between farmers and advisers' perceptions. This suggests it is important to assess both perspectives when designing effective advice delivery mechanisms and for policy makers to consider who is most appropriate to effectively deliver farm advice

    Combining historical agricultural and climate datasets sheds new light on early 20th century barley performance

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    Barley (Hordeum vulgare ssp. vulgare) is cultivated globally across a wide range of environments, both in highly productive agricultural systems and in subsistence agriculture and provides valuable feedstock for the animal feed and malting industries. However, as the climate changes there is an urgent need to identify adapted barley varieties that will consistently yield highly under increased environmental stresses. Our ability to predict future local climates is only as good as the skill of the climate model, however we can look back over 100 years with much greater certainty. Historical weather datasets are an excellent resource for identifying causes of historical yield variability. In this research we combined recently digitised historical weather data from the early 20th century with published Irish spring barley trials data for two heritage varieties: Archer and Goldthorpe, following an analysis first published by Student in 1923. Using linear mixed models, we show that interannual variation in observed spring barley yields can be partially explained by recorded weather variability, in particular July maximum temperature and rainfall, and August maximum temperature. We find that while Archer largely yields more highly, Goldthorpe is more stable under wetter growing conditions, highlighting the importance of considering growing climate in variety selection. Furthermore, this study demonstrates the benefits of access to historical trials and climatic data and the importance of incorporating climate data in modern day breeding programmes to improve climate resilience of future varieties

    Predicting death in young offenders: a retrospective cohort study

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    Objective: To examine predictors of death in young offenders who have received a custodial sentence using data routinely collected by juvenile justice services. Design: A retrospective cohort of 2849 (2625 male) 11–20-year-olds receiving their first custodial sentence between 1 January 1988 and 31 December 1999 was identified. Main outcome measures: Deaths, date and primary cause of death ascertained from study commencement to 1 March 2003 by data-matching with the National Death Index; measures comprising year of and age at admission, sex, offence profile, any drug offence, multiple admissions and ethnic and Indigenous status, obtained from departmental records. Results: Theoverallmortalityratewas7.2deathsper1000person-yearsofobservation. Younger admission age (hazard ratio [HR], 1.4; 95% CI, 1.0–1.9), repeat admissions (HR, 1.8; 95% CI, 1.1–2.9) and drug offences (HR, 1.5; 95% CI, 1.0–2.1) predicted early death. The role of ethnicity/Aboriginality could only be assessed in cohort entrants from 1996 to 1999. The Asian subcohort showed higher risk of death from drug-related causes (HR, 2.5; 95% CI, 1.1–5.5), more drug offences (relative risk ratio [RRR], 13; 95% CI, 8.5–20.0) and older admission age (oldest group v youngest: RRR, 9.3; 95% CI, 1.3–68.0) than non- Indigenous Australians. Although higher mortality was not identified in Indigenous Australians, this group was more likely to be admitted younger (oldest v youngest: RRR, 0.31; 95% CI, 0.15–0.63) and experience repeat admissions (RRR, 1.6; 95% CI, 1.0–2.4). Conclusions: Young offenders have a much higher death rate than other young Victorians. Early detention, multiple detentions and drug-related offences are indicators of high mortality risk. For these offenders, targeted healthcare while in custody and further mental healthcare and social support after release appear essential if we are to reduce the mortality rate in this group
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