23,531 research outputs found

    Chelate-modified polymers for atmospheric gas chromatography

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    Chromatographic materials were developed to serve as the stationary phase of columns used in the separation of atmospheric gases. These materials consist of a crosslinked porous polymer matrix, e.g., a divinylbenzene polymer, into which has been embedded an inorganic complexed ion such as N,N'-ethylene-bis-(acetylacetoniminato)-cobalt (2). Organic nitrogenous bases, such as pyridine, may be incorporated into the chelate polymer complexes to increase their chromatographic utility. With such materials, the process of gas chromatography is greatly simplified, especially in terms of time and quantity of material needed for a gas separation

    Predictors of refusal to participate: a longitudinal health survey of the elderly in Australia

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    BACKGROUND: The loss of participants in longitudinal studies due to non-contact, refusal or death can introduce bias into the results of such studies. The study described here examines reasons for refusal over three waves of a survey of persons aged ≥ 70 years. METHODS: In a longitudinal study involving three waves, participants were compared to those who refused to participate but allowed an informant to be interviewed and to those who refused any participation. RESULTS: At Wave 1 both groups of Wave 2 non-participants had reported lower occupational status and fewer years of education, had achieved lower verbal IQ scores and cognitive performance scores and experienced some distress from the interview. Those with an informant interview only were in poorer physical health than those who participated and those who refused. Depression and anxiety symptoms were not associated with non-participation. Multivariate analyses found that verbal IQ and cognitive impairment predicted refusal. Results were very similar for refusers at both Waves 2 and 3. CONCLUSIONS: Longitudinal studies of the elderly may over estimate cognitive performance because of the greater refusal rate of those with poorer performance. However, there is no evidence of bias with respect to anxiety or depression

    Mathematical aspects of intertwining operators: the role of Riesz bases

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    In this paper we continue our analysis of intertwining relations for both self-adjoint and not self-adjoint operators. In particular, in this last situation, we discuss the connection with pseudo-hermitian quantum mechanics and the role of Riesz bases.Comment: Journal of Physics A, in pres

    R-HybrID: Evolution of agent controllers with a hybridisation of indirect and direct encodings

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    Neuroevolution, the optimisation of artificial neural networks (ANNs) through evolutionary computation, is a promising approach to the synthesis of controllers for autonomous agents. Traditional neuroevolution approaches employ direct encodings, which are limited in their ability to evolve complex or large-scale controllers because each ANN parameter is independently optimised. Indirect encodings, on the other hand, facilitate scalability because each gene can be reused multiple times to construct the ANN, but are biased towards regularity and can become ineffective when irregularity is required. To address such limitations, we introduce a novel algorithm called R-HybrID. In R-HybrID, controllers have both indirectly encoded and directly encoded structure. Because the portion of structure following a specific encoding is under evolutionary control, R-HybrID can automatically find an appropriate encoding combination for a given task. We assess the performance of R-HybrID in three tasks: (i) a high-dimensional visual discrimination task that requires geometric principles to be evolved, (ii) a challenging benchmark for modular robotics, and (iii) a memory task that has proven difficult for current algorithms because it requires effectively accumulating neural structure for cognitive behaviour to emerge. Our results show that R-HybrID consistently outperforms three stateof-the-art neuroevolution algorithms, and effectively evolves complex controllers and behaviours.info:eu-repo/semantics/publishedVersio

    A theoretical review of interpersonal emotion regulation in eating disorders: Enhancing knowledge by bridging interpersonal and affective dysfunction

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    This work is licensed under a Creative Commons Attribution 4.0 International License.Individuals with eating disorders (EDs) frequently report interpersonal and affective dysfunction. A useful lens for uniting these ideas is through the framework of interpersonal emotion regulation (IER), which consists of the ways others assist a distressed individual and how this shapes his or her subsequent emotional, behavioral, and cognitive responses. In this theoretical review, we provide an overview of the rationale for exploring IER and review IER processes in this population using the framework of the Process Model of Emotion Regulation. Finally, we offer suggestions for next steps in conducting research. IER offers a parsimonious way to explore social and emotional constructs related to ED pathology and may provide potential targets for prevention and intervention in these difficult-to-treat disorders.NIMH grant K23MH11286

    Integral field spectroscopy of QSO host galaxies

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    We describe a project to study the state of the ISM in ~20 low redshift (z<0.3) QSO host galaxies observed with the PMAS integral field spectrograph. We describe method developement to access the stellar and gas component of the spectrum without the strong nuclear emission to access the host galaxy properties also in the central region. It shows that integral field spectroscopy promises to be very efficient to study the gas distribution and its velocity field, and also spatially resolved stellar population in the host galaxies also of luminous AGN.Comment: 4 pages, 6 figures, Euro3D Science Workshop, Cambridge, May 2003, AN, accepte

    Investigation of the shear-mechanical and dielectric relaxation processes in two mono-alcohols close to the glass transition

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    Shear-mechanical and dielectric measurements on the two monohydroxy (mono-alcohol) molecular glass formers 2-ethyl-1-hexanol and 2-butanol close to the glass transition temperature are presented. The shear-mechanical data are obtained using the piezoelectric shear-modulus gauge method covering frequencies from 1mHz to 10kHz. The shear-mechanical relaxation spectra show two processes, which follow the typical scenario of a structural (alpha) relaxation and an additional (Johari-Goldstein) beta relaxation. The dielectric relaxation spectra are dominated by a Debye-type peak with an additional non-Debye peak visible. This Debye-type relaxation is a common feature peculiar to mono-alcohols. The time scale of the non-Debye dielectric relaxation process is shown to correspond to the mechanical structural (alpha) relaxation. Glass-transition temperatures and fragilities are reported based on the mechanical alpha relaxation and the dielectric Debye-type process, showing that the two glass-transition temperatures differ by approximately 10K and that the fragility based on the Debye-type process is a factor of two smaller than the structural fragility. If a mechanical signature of the Debye-type relaxation exists in these liquids, its relaxation strength is at most 1% and 3% of the full relaxation strength of 2-butanol and 2-ethyl-1-hexanol respectively. These findings support the notion that it is the non-Debye dielectric relaxation process that corresponds to the structural alpha relaxation in the liquid.Comment: 8 pages, 6 figures. Minor corrections, updated figures, more dielectric data show

    Online hyper-evolution of controllers in multirobot systems

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    In this paper, we introduce online hyper-evolution (OHE) to accelerate and increase the performance of online evolution of robotic controllers. Robots executing OHE use the different sources of feedback information traditionally associated with controller evaluation to find effective evolutionary algorithms and controllers online during task execution. We present two approaches: OHE-fitness, which uses the fitness score of controllers as the criterion to select promising algorithms over time, and OHE-diversity, which relies on the behavioural diversity of controllers for algorithm selection. Both OHE-fitness and OHE-diversity are distributed across groups of robots that evolve in parallel. We assess the performance of OHE-fitness and of OHE-diversity in two foraging tasks with differing complexity, and in five configurations of a dynamic phototaxis task with varying evolutionary pressures. Results show that our OHE approaches: (i) outperform multiple state-of-the-art algorithms as they facilitate controllers with superior performance and faster evolution of solutions, and (ii) can increase effectiveness at different stages of evolution by combining the benefits of multiple algorithms over time. Overall, our study shows that OHE is an effective new paradigm to the synthesis of controllers for robots.info:eu-repo/semantics/acceptedVersio
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