| 1. |
- Ferizi, U., et al.
(författare)
-
Diffusion MRI microstructure models with in vivo human brain Connectome data: results from a multi-group comparison
- 2017
-
Ingår i: NMR in Biomedicine. - : Wiley. - 0952-3480 .- 1099-1492. ; 30:9, s. Article no e3734 -
-
Tidskriftsartikel (refereegranskat)abstract
- A large number of mathematical models have been proposed to describe the measured signal in diffusion-weighted (DW) magnetic resonance imaging (MRI). However, model comparison to date focuses only on specific subclasses, e.g. compartment models or signal models, and little or no information is available in the literature on how performance varies among the different types of models. To address this deficiency, we organized the White Matter Modeling Challenge' during the International Symposium on Biomedical Imaging (ISBI) 2015 conference. This competition aimed to compare a range of different kinds of models in their ability to explain a large range of measurable in vivo DW human brain data. Specifically, we assessed the ability of models to predict the DW signal accurately for new diffusion gradients and b values. We did not evaluate the accuracy of estimated model parameters, as a ground truth is hard to obtain. We used the Connectome scanner at the Massachusetts General Hospital, using gradient strengths of up to 300mT/m and a broad set of diffusion times. We focused on assessing the DW signal prediction in two regions: the genu in the corpus callosum, where the fibres are relatively straight and parallel, and the fornix, where the configuration of fibres is more complex. The challenge participants had access to three-quarters of the dataset and their models were ranked on their ability to predict the remaining unseen quarter of the data. The challenge provided a unique opportunity for a quantitative comparison of diverse methods from multiple groups worldwide. The comparison of the challenge entries reveals interesting trends that could potentially influence the next generation of diffusion-based quantitative MRI techniques. The first is that signal models do not necessarily outperform tissue models; in fact, of those tested, tissue models rank highest on average. The second is that assuming a non-Gaussian (rather than purely Gaussian) noise model provides little improvement in prediction of unseen data, although it is possible that this may still have a beneficial effect on estimated parameter values. The third is that preprocessing the training data, here by omitting signal outliers, and using signal-predicting strategies, such as bootstrapping or cross-validation, could benefit the model fitting. The analysis in this study provides a benchmark for other models and the data remain available to build up a more complete comparison in the future.
|
|
| 2. |
- Aschemann-Witzel, J., et al.
(författare)
-
The who, where and why of choosing suboptimal foods : Consequences for tackling food waste in store
- 2019
-
Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 236
-
Tidskriftsartikel (refereegranskat)abstract
- Food stores have begun to tackle food waste at the point of sale. They do so by selling ‘suboptimal’ food before it is wasted, typically with a price reduction. However, efficiency of this food waste avoidance action can be improved by knowing for which product category, which store type, which accompanying communication, and which consumer characteristics this action works best. This study uses an experimental online survey conducted in five North western European countries to investigate the effect of communication appealing to either self- or others-centred motives in either supermarkets or farmers' markets, for packaged and for fresh food. It is found that both messages – communicating budget saving or an emotional appeal - are effective in increasing choice likelihood. Store type affects choice likelihood of suboptimal packaged, while others-centred values and trust in the store affects choice likelihood for suboptimal fresh food. Communication improves quality perception of suboptimal fresh food. Findings imply that fresh suboptimal foods lend themselves more to be promoted with others-centred messages, or to be targeted at consumers with others-centred values. Sales of suboptimal food in the store should be accompanied by communication, and such efforts to tackle food waste in the store should focus on fresh food in particular.
|
|
