918 research outputs found
Micro-Engineered Devices for Motion Energy Harvesting
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Conceptualising the policy practice and behavioural research relationship
BackgroundPolicy is frequently identified in the behavioural nutrition and physical activity research literature as a necessary component of effective research and practice. The purpose of this commentary is to promote a dialogue to contribute towards the further development of conceptual understandings and theories of the relationship between policy practice and behavioural research and how these two activities might work synergistically to improve public health outcomes.MethodsDrawing on policy and public health literature, this commentary presents a a conceptual model of the interaction and mediation between nutrition and physical activity-relevant policy and behavioural nutrition and physical activity research, environments, behaviours and public health implications. The selling of food in school canteens in several Australian states is discussed to illustrate components of the relationship and the interactions among its components.ResultsThe model depicts a relationship that is interdependent and cyclic. Policy contributes to the relationship through its role in shaping environmental and personal-cognitive determinants of behaviours and through these determinants it can induce behaviour change. Behavioural research describes behaviours, identifies determinants of behaviour change and therefore helps inform policy development and monitor and evaluate its impact.ConclusionThe model has implications for guiding behavioural research and policy practice priorities to promote public health outcomes. In particular, we propose that policy practice and behavioural research activities can be strengthened by applying to each other the theories from the scientific disciplines informing these respective activities. Behavioural science theories can be applied to help understand policy-making and assist with disseminating research into policy and practice. In turn, policy science theories can be applied to support the \u27institutionalisation\u27 of commitments to ongoing behavioural research.<br /
Piezoelectric wind velocity sensor based on the variation of galloping frequency with drag force
In this paper, we demonstrate a miniature energy harvesting wind velocity sensor of simple, low-cost construction, based on a single-degree-of-freedom galloping structure. The sensor consists of a prismatic bluff body with a triangular cross section attached to the free end of acantilever incorporating a commercial polyvinylidene fluoride piezoelectric film. In the wind, the bluff body causes vibration of the cantileverbased on galloping, and the piezoelectric film converts the vibration energy into an electrical signal. We have observed a negative correlationbetween the wind velocity and the vibration frequency, and we demonstrate that this relationship can be used to detect wind velocity directlywith useful accuracy. A simple theoretical model indicates that the frequency shift can be accounted for by the effect of the axial loading dueto form drag. The model shows close agreement with the experimental results. In wind tunnel tests, a prototype wind velocity sensor basedon this principle could measure wind velocities from 4.45 to 10 m/s, with the measured velocity typically being within 4% of the referencevalue obtained using a Pitot tube
Microfluidics at fibre tip for nanolitre delivery and sampling
Delivery and sampling nanolitre volumes of liquid can benefit new invasive surgical procedures. However, the dead volume and difficulty in generating constant pressure flow limits the use of small tubes such as capillaries. This work demonstrates sub-millimetre microfluidic chips assembled directly on the tip of a bundle of two hydrophobic coated 100 ÎĽm capillaries to deliver nanolitre droplets in liquid environments. Droplets are created in a specially designed nanopipette and propelled by gas through the capillary to the microfluidic chip where a passive valve mechanism separates liquid from gas, allowing their delivery. By adjusting the driving pressure and microfluidic geometry we demonstrate both partial and full delivery of 10 nanolitre droplets with 0.4 nanolitre maximum error, as well as sampling from the environment. This system will enable drug delivery and sampling with minimally invasive probes, facilitating continuous liquid biopsy for disease monitoring and in-vivo drug screening
Evaluating the accuracy of diffusion MRI models in white matter
Models of diffusion MRI within a voxel are useful for making inferences about
the properties of the tissue and inferring fiber orientation distribution used
by tractography algorithms. A useful model must fit the data accurately.
However, evaluations of model-accuracy of some of the models that are commonly
used in analyzing human white matter have not been published before. Here, we
evaluate model-accuracy of the two main classes of diffusion MRI models. The
diffusion tensor model (DTM) summarizes diffusion as a 3-dimensional Gaussian
distribution. Sparse fascicle models (SFM) summarize the signal as a linear sum
of signals originating from a collection of fascicles oriented in different
directions. We use cross-validation to assess model-accuracy at different
gradient amplitudes (b-values) throughout the white matter. Specifically, we
fit each model to all the white matter voxels in one data set and then use the
model to predict a second, independent data set. This is the first evaluation
of model-accuracy of these models. In most of the white matter the DTM predicts
the data more accurately than test-retest reliability; SFM model-accuracy is
higher than test-retest reliability and also higher than the DTM, particularly
for measurements with (a) a b-value above 1000 in locations containing fiber
crossings, and (b) in the regions of the brain surrounding the optic
radiations. The SFM also has better parameter-validity: it more accurately
estimates the fiber orientation distribution function (fODF) in each voxel,
which is useful for fiber tracking
Adoption of an infection prevention and control programme (IPCP) in the Republic of Kiribati: a case study in diffusion of innovations theory
Abstract presented at the International Conference on Prevention & Infection Control (ICPIC 2011) Geneva, Switzerland. 29 June - 2 July 201
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