1,576 research outputs found

    Electrokinetic and hydrodynamic properties of charged-particles systems: From small electrolyte ions to large colloids

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    Dynamic processes in dispersions of charged spherical particles are of importance both in fundamental science, and in technical and bio-medical applications. There exists a large variety of charged-particles systems, ranging from nanometer-sized electrolyte ions to micron-sized charge-stabilized colloids. We review recent advances in theoretical methods for the calculation of linear transport coefficients in concentrated particulate systems, with the focus on hydrodynamic interactions and electrokinetic effects. Considered transport properties are the dispersion viscosity, self- and collective diffusion coefficients, sedimentation coefficients, and electrophoretic mobilities and conductivities of ionic particle species in an external electric field. Advances by our group are also discussed, including a novel mode-coupling-theory method for conduction-diffusion and viscoelastic properties of strong electrolyte solutions. Furthermore, results are presented for dispersions of solvent-permeable particles, and particles with non-zero hydrodynamic surface slip. The concentration-dependent swelling of ionic microgels is discussed, as well as a far-reaching dynamic scaling behavior relating colloidal long- to short-time dynamics

    Nationwide forestry applications program. Analysis of forest classification accuracy

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    The development of LANDSAT classification accuracy assessment techniques, and of a computerized system for assessing wildlife habitat from land cover maps are considered. A literature review on accuracy assessment techniques and an explanation for the techniques development under both projects are included along with listings of the computer programs. The presentations and discussions at the National Working Conference on LANDSAT Classification Accuracy are summarized. Two symposium papers which were published on the results of this project are appended

    Does a high level of multimodality mean less car use? An exploration of multimodality trends in England

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    Some existing studies have suggested that a higher level of multimodality—the use of more than one transport mode within a given period of time—may be desirable to achieve societies less dependent on cars. The aim of this study was to investigate the trends in individual multimodality in England. In addition, we explored whether these trends were homogenous, i.e. similar between socio-economic characteristics, and whether changes in multimodality corresponded with changes in car use and the use of other transport modes. Our analyses showed that in contrast to reported trends in existing research, the level of multimodality in England decreased between 1995 and 2015. These trends stratified by income were diverging, which may imply that inequality in transport opportunities may be increasing. In contrast, the trends for age and gender were converging. In addition, we found that the car mode share remained fairly stable and absolute car use decreased since 2004, whilst multimodality decreased. This suggests that there is no necessary relationship between aggregate levels of car use and the average individual level of multimodality. Moreover, our analyses showed that these trends were very similarly independent of which indicator was applied. This indicates that for analysing trends in multimodality, the choice of indicator may not be that important, and indicators that are elementary to calculate and easy to interpret, e.g. number of modes used, highlight trends that are highly consistent with more sophisticated metrics. This paper finishes with a discussion of the implications of these findings

    Early Globus Pallidus Internus Stimulation in Pediatric Patients With Generalized Primary Dystonia: Long-Term Efficacy and Safety

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    Primary generalized dystonia presents mainly at a young age and commonly is severely disabling. The authors report the long-term follow-up (mean, 73 months; range, 50-101 months) of 5 pediatric patients (mean age at surgery 13 years; range, 8-16 years) undergoing globus pallidus internus deep brain stimulation. Mean improvement in the Burke-Fahn-Marsden movement score was 67.4% (range, 47.0%-87.5%), 75.4% (range, 61.5%-91.7%), and 83.5% (range, 72.0%-93.3%) at 3 months, 12 months, and long-term follow-up (>36 months), respectively. Hardware problems (electrode dislocation/breakage of extension cable, and imminent perforation of extension cable) were observed in 2 patients (operative revision without sequelae). Except for mild dysarthria in 2 patients, no other therapy-related morbidity was observed. The authors found globus pallidus internus stimulation to offer a very effective and safe therapy in pediatric patients with primary dystonia. Early neurosurgical intervention seems to be crucial to prevent irreversible impairment of motor function

    The public bicycle-sharing scheme in Brisbane, Australia: Evaluating the influence of its introduction on changes in time spent cycling amongst a middle- and older-age population

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    Background: Active travel may improve individual health as it contributes to higher levels of physical activity, particularly in an aging society. Bicycle-sharing schemes may contribute to public health by encouraging active travel. Aim: To investigate whether exposure to a bicycle-sharing scheme—measured as residential proximity to a bicycle station—was associated with the propensity to use it. Second, we aimed to study the extent to which exposure to the scheme was associated with a change in time spent cycling. Method: In this natural-experimental study, we analysed a large panel of residents in Brisbane, Australia, who were surveyed before and after the introduction of a bicycle-sharing scheme in 2010. Data were collected as part of the HABITAT study, a multilevel longitudinal investigation of physical activity and health among ‘baby boomers’ (persons aged 40–65). Data were collected in 2009 (n = 7866), 2011 (n = 6900), and 2013 (n = 6520). Two self-reported outcome variables were examined: (1) a stages-of-change variable measuring the likelihood of using the scheme and the intention to use it in the future, and (2) change in time spent cycling between 2009 and 2013. Results: In the unadjusted model, proximity was significantly associated with stages of change, but became non-significant after adjustment. Moreover, higher levels of exposure to the intervention did not predict a change in time spent cycling. Younger respondents and respondents with a higher education level were more likely to consider using the bicycle-sharing scheme. Individuals who had a college degree were more likely to have used this scheme. Conclusion: Residential proximity to a bicycle-sharing station was not found to be associated with the use of the bicycle-sharing scheme nor did its introduction significantly predict an increase in time spent cycling. Other interventions may be more supportive of increasing cycling in the baby boomer cohort, and, thereby, improving their overall health

    Update and review of accuracy assessment techniques for remotely sensed data

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    Research performed in the accuracy assessment of remotely sensed data is updated and reviewed. The use of discrete multivariate analysis techniques for the assessment of error matrices, the use of computer simulation for assessing various sampling strategies, and an investigation of spatial autocorrelation techniques are examined

    Millimeter wave transmission studies of YBa2Cu3O7-delta thin films in the 26.5 to 40.0 GHz frequency range

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    Millimeter wave transmission measurements through YBa2Cu3O(7-delta) thin films on MgO, ZrO2 and LaAlO3 substrates, are reported. The films (approx. 1 micron) were deposited by sequential evaporation and laser ablation techniques. Transition temperatures T sub c, ranging from 89.7 K for the Laser Ablated film on LaAlO3 to approximately 72 K for the sequentially evaporated film on MgO, were obtained. The values of the real and imaginary parts of the complex conductivity, sigma 1 and sigma 2, are obtained from the transmission data, assuming a two fluid model. The BCS approach is used to calculate values for an effective energy gap from the obtained values of sigma sub 1. A range of gap values from 2 DELTA o/K sub B T sub c = 4.19 to 4.35 was obtained. The magnetic penetration depth is evaluated from the deduced values of sigma 2. These results are discussed together with the frequency dependence of the normalized transmission amplitude, P/P sub c, below and above T sub c
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