Convective regularization for optical flow

We argue that the time derivative in a fixed coordinate frame may not be the most appropriate measure of time regularity of an optical flow field. Instead, for a given velocity field $v$ we consider the convective acceleration $v_t + \nabla v v$ which describes the acceleration of objects moving according to $v$. Consequently we investigate the suitability of the nonconvex functional $\|v_t + \nabla v v\|^2_{L^2}$ as a regularization term for optical flow. We demonstrate that this term acts as both a spatial and a temporal regularizer and has an intrinsic edge-preserving property. We incorporate it into a contrast invariant and time-regularized variant of the Horn-Schunck functional, prove existence of minimizers and verify experimentally that it addresses some of the problems of basic quadratic models. For the minimization we use an iterative scheme that approximates the original nonlinear problem with a sequence of linear ones. We believe that the convective acceleration may be gainfully introduced in a variety of optical flow models

Optical Flow on Moving Manifolds

Optical flow is a powerful tool for the study and analysis of motion in a sequence of images. In this article we study a Horn-Schunck type spatio-temporal regularization functional for image sequences that have a non-Euclidean, time varying image domain. To that end we construct a Riemannian metric that describes the deformation and structure of this evolving surface. The resulting functional can be seen as natural geometric generalization of previous work by Weickert and Schn\"orr (2001) and Lef\`evre and Baillet (2008) for static image domains. In this work we show the existence and wellposedness of the corresponding optical flow problem and derive necessary and sufficient optimality conditions. We demonstrate the functionality of our approach in a series of experiments using both synthetic and real data.Comment: 26 pages, 6 figure

Decomposition of Optical Flow on the Sphere

We propose a number of variational regularisation methods for the estimation and decomposition of motion fields on the $2$-sphere. While motion estimation is based on the optical flow equation, the presented decomposition models are motivated by recent trends in image analysis. In particular we treat $u+v$ decomposition as well as hierarchical decomposition. Helmholtz decomposition of motion fields is obtained as a natural by-product of the chosen numerical method based on vector spherical harmonics. All models are tested on time-lapse microscopy data depicting fluorescently labelled endodermal cells of a zebrafish embryo.Comment: The final publication is available at link.springer.co

Innovating on Well Biofouling Remediation: A Bacteriophage Cocktail Approach

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Arum-type of arbuscular mycorrhizae, dark septate endophytes and Olpidium spp. in fine roots of container-grown seedlings of Sorbus torminalis (Rosaceae)

The aim of this study was to determine the mycorrhizal status of nursery seedlings of the wild service tree (Sorbus torminalis), which belongs to the Rosaceae family. Its mycorrhizal associations are still fragmentarily known, and data from the few existing studies indicate that it forms ectomycorrhizal symbiosis (ECM). We analyzed the degree of mycorrhizal colonization of thirty 2-year-old container-grown S. torminalis nursery seedlings, which belonged to three single-tree progenies. The roots were dominated by arbuscular mycorrhizae (AM), with the morphology of the Arum-type containing arbuscules, vesicles and hyphae; however, no ECM structures were found. The degree of root colonization of the analyzed seedlings by AM fungi was 83.6% and did not differ significantly between the three single-tree progenies. In addition to AM, structures of dark septate endophytes (0.7%) and sporangia of Olpidium spp. (1.1%) were found in wild service tree roots. In agreement with previous studies, we confirmed arbuscular mycorrhizae for S. torminalis. Moreover, this is the first report that roots of this Sorbus species show the Arum-type morphology of AM and are associated with Olpidium species

Review of Economic Submissions to NICE Medical Technologies Evaluation Programme

The economic evaluation of medical devices is increasingly used to inform decision making on adopting new or novel technologies; however, challenges are inevitable due to the unique characteristics of devices. Cost-consequence analyses are recommended and employed by the English National Institute for Health and Care Excellence (NICE) Medical Technologies Evaluation Programme (MTEP) to help address these challenges. The aim of this work was to review the critiques raised for previous MTEP submissions and explore if there were common problems across submissions. We reviewed a sample of 12 economic submissions to MTEP representing 50 % of 24 sets of guidance issued to July 2015. For each submission, we reviewed the External Assessment Centre's (EAC) report and the guidance document produced by NICE. We identified the main problems raised by the EAC's assessments and the committee's considerations for each submission, and explored strategies for improvement. We found that the identification and measurement of costs and consequences are the main shortcomings within economic submissions to MTEP. Together, these shortcomings accounted for 42 % of criticisms by the EACs among the reviewed submissions. In certain circumstances problems with these shortcomings may be unavoidable, for example, if there is a limited evidence base for the device being appraised. Nevertheless, strategies can often be adopted to improve submissions, including the use of more appropriate time horizons, whilst cost and resource use information should be taken, where possible, from nationally representative sources