Fuzzy Fibers: Uncertainty in dMRI Tractography

Fiber tracking based on diffusion weighted Magnetic Resonance Imaging (dMRI) allows for noninvasive reconstruction of fiber bundles in the human brain. In this chapter, we discuss sources of error and uncertainty in this technique, and review strategies that afford a more reliable interpretation of the results. This includes methods for computing and rendering probabilistic tractograms, which estimate precision in the face of measurement noise and artifacts. However, we also address aspects that have received less attention so far, such as model selection, partial voluming, and the impact of parameters, both in preprocessing and in fiber tracking itself. We conclude by giving impulses for future research

Learners' use of domain-specific computer-based feedback to overcome logical circularity in deductive proving in geometry

This is the final version of the article. Available from Springer Verlag via the DOI in this record.Much remains under-researched in how learners make use of domain-specific feedback. In this paper, we report on how learners’ can be supported to overcome logical circularity during their proof construction processes, and how feedback supports the processes. We present an analysis of three selected episodes from five learners who were using a web-based proof learning support system. Through this analysis we illustrate the various errors they made, including using circular reasoning, which were related to their understanding of hypothetical syllogism as an element of the structure of mathematical proof. We found that, by using the computer-based feedback and, for some, teacher intervention, the learners started considering possible combinations of assumptions and conclusion, and began realising when their proof fell into logical circularity. Our findings raise important issues about the nature and role of computer-based feedback such as how feedback is used by learners, and the importance of teacher intervention in computer-based learning environments.This research is supported by the Daiwa Anglo-Japanese foundation (No. 7599/8141) and the Grant-in-Aid for Scientific Research (Nos. 15K12375, 16H03057), Ministry of Education, Culture, Sports, Science, and Technology, Japan

Measurement of Δ\Delta and K∗K^{*} Production in dd+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

The measurements of the transverse momentum spectra and the invariant mass distributions of $\Delta(1232)$ $\to \pi p$, $K^{*}(892)\to \pi K$ resonances in $d$+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV using the STAR Time Projection Chamber (TPC) at RHIC are presented. The in-medium modification of the $\Delta$ and $K^{*}$ mass and width has been studied as a function of transverse momentum ($p_T$). The particle ratios $K^{*}/K$, $\Delta/p$ and the average transverse momentum ($$) as a function of different collision centrality has been reported. The nuclear modification factors ($R_{CP}$ and $R_{dAu}$) of $\Delta$ and $K^{*}$ are discussed.Comment: 5 pages, 9 figures, proceeding (poster) of the 18th International Conference on Nucleus-Nucleus Collisions (QM2005), Aug.4-9, Budapest, Hungar

Solid-state photoreactivity of 9-substituted acridizinium bromide salts

A series of substituted acridizinium bromides was studied to determine how substituents affect the regioselectivity of the solid-state [4 + 4] photodimerisation.This is the final version. It was first published by RSC at http://pubs.rsc.org/en/Content/ArticleLanding/2014/CE/C4CE01622J#!divAbstrac

User Testing to Improve Retrieval and Comprehension of Information in Guidelines to Improve Medicines Safety

Objective: The aim of the study was to investigate the effectiveness of user testing for improving healthcare professionals’ retrieval and comprehension of information in medicines guidelines. Methods: The United Kingdom’s Injectable Medicines Guide was selected as a case study. This gives guidance to nurses on preparing and administering intravenous medicines on hospital wards, in line with standard UK practice. Three rounds of user testing were completed with 10 hospital nurses per round, using the Injectable Medicines Guide for voriconazole and aminophylline. Participants used the guidelines to answer 17 questions related to the administration of these medicines. Answers were scored for “finding” and “understanding” the required information. Semistructured interviews explored participants’ opinions of guideline content, design, and wording, with responses analyzed thematically. The guidelines were revised between rounds. Results: In round 1, 8 of 17 questions were answered correctly by all participants. Participants had difficulty with dose, dilution, administration rate, and adverse effects questions. Revisions included new subsections and increased calculation support. In round 2, 14 of 17 questions were answered correctly by all participants. Difficulty persisted with dose and administration rate questions and further revisions made. In round 3, 15 of 17 questions were answered correctly by all participants. Across all rounds, participants considered appropriate subheadings and information order as important for fast location of information. Specific, detailed, and practical instructions were perceived as important to improve understandability and usefulness. Conclusions: Key information in medicines guidelines may not be found and/or understood by healthcare professionals. User testing increased information retrieval and comprehension and could have an important role in improving the safety of medicines use

SPHERIOUSLY? The challenges of estimating sphere radius non-invasively in the human brain from diffusion MRI

The Soma and Neurite Density Imaging (SANDI) three-compartment model was recently proposed to disentangle cylindrical and spherical geometries, attributed to neurite and soma compartments, respectively, in brain tissue. There are some recent advances in diffusion-weighted MRI signal encoding and analysis (including the use of multiple so-called ’b-tensor’ encodings and analysing the signal in the frequency-domain) that have not yet been applied in the context of SANDI. In this work, using: (i) ultra-strong gradients; (ii) a combination of linear, planar, and spherical b-tensor encodings; and (iii) analysing the signal in the frequency domain, three main challenges to robust estimation of sphere size were identified: First, the Rician noise floor in magnitude-reconstructed data biases estimates of sphere properties in a non-uniform fashion. It may cause overestimation or underestimation of the spherical compartment size and density. This can be partly ameliorated by accounting for the noise floor in the estimation routine. Second, even when using the strongest diffusion-encoding gradient strengths available for human MRI, there is an empirical lower bound on the spherical signal fraction and radius that can be detected and estimated robustly. For the experimental setup used here, the lower bound on the sphere signal fraction was approximately 10%. We employed two different ways of establishing the lower bound for spherical radius estimates in white matter. The first, examining power-law relationships between the DW-signal and diffusion weighting in empirical data, yielded a lower bound of , while the second, pure Monte Carlo simulations, yielded a lower limit of and in this low radii domain, there is little differentiation in signal attenuation. Third, if there is sensitivity to the transverse intra-cellular diffusivity in cylindrical structures, e.g., axons and cellular projections, then trying to disentangle two diffusion-time-dependencies using one experimental parameter (i.e., change in frequency-content of the encoding waveform) makes spherical radii estimates particularly challenging. We conclude that due to the aforementioned challenges spherical radii estimates may be biased when the corresponding sphere signal fraction is low, which must be considered

Dataset for "User testing to improve retrieval and comprehension of information in guidelines to improve medicines safety"

This dataset describes a series of user tests designed to improve the retrieval and comprehension of information by nurses from the NHS Injectable Medicines Guide. It includes the research protocol, data collection tools, interview transcriptions and thematic analysis, participant demographics and numerical outcome data.Nvivo version 11 used for thematic analysis

User-testing guidelines to improve the safety of intravenous medicines administration: a randomised in situ simulation study

Background: User-testing and subsequent modification of clinical guidelines increases health professionals’ information retrieval and comprehension. No study has investigated whether this results in safer care. Objective: To compare the frequency of medication errors when administering an intravenous medicine using the current National Health Service Injectable Medicines Guide (IMG) versus an IMG version revised with user-testing. Method: Single-blind, randomised parallel group in situ simulation. Participants were on-duty nurses/midwives who regularly prepared intravenous medicines. Using a training manikin in their clinical area, participants administered a voriconazole infusion, a high-risk medicine requiring several steps to prepare. They were randomised to use current IMG guidelines or IMG guidelines revised with user-testing. Direct observation was used to time the simulation and identify errors. Participant confidence was measured using a validated instrument. The primary outcome was the percentage of simulations with at least one moderatesevere IMG-related error, with error severity classified by an expert panel. Results: In total, 133 participants were randomised to current guidelines and 140 to user-tested guidelines. Fewer moderate-severe IMG-related errors occurred with the user-tested guidelines (n=68, 49%) compared with current guidelines (n=79, 59%), but this difference was not statistically significant (risk ratio: 0.82; 95% CI 0.66 to 1.02). Significantly more simulations were completed without any IMG-related errors with the usertested guidelines (n=67, 48%) compared with current guidelines (n=26, 20%) (risk ratio: 2.46; 95% CI 1.68 to 3.60). Median simulation completion time was 1.6min (95% CI 0.2 to 3.0) less with the user-tested guidelines. Participants who used user-tested guidelines reported greater confidence. Conclusion: User-testing injectable medicines guidelines reduces the number of errors and the time taken to prepare and administer intravenous medicines, while increasing staff confidence. Trial registration: number researchregistry5275

User-testing guidelines to improve the safety of intravenous medicines administration: a randomised in situ simulation study

Background: User-testing and subsequent modification of clinical guidelines increases health professionals’ information retrieval and comprehension. No study has investigated whether this results in safer care. Objective: To compare the frequency of medication errors when administering an intravenous medicine using the current National Health Service Injectable Medicines Guide (IMG) versus an IMG version revised with user-testing. Method: Single-blind, randomised parallel group in situ simulation. Participants were on-duty nurses/midwives who regularly prepared intravenous medicines. Using a training manikin in their clinical area, participants administered a voriconazole infusion, a high-risk medicine requiring several steps to prepare. They were randomised to use current IMG guidelines or IMG guidelines revised with user-testing. Direct observation was used to time the simulation and identify errors. Participant confidence was measured using a validated instrument. The primary outcome was the percentage of simulations with at least one moderate-severe IMG-related error, with error severity classified by an expert panel. Results: In total, 133 participants were randomised to current guidelines and 140 to user-tested guidelines. Fewer moderate-severe IMG-related errors occurred with the user-tested guidelines (n=68, 49%) compared with current guidelines (n=79, 59%), but this difference was not statistically significant (risk ratio: 0.82; 95% CI 0.66 to 1.02). Significantly more simulations were completed without any IMG-related errors with the user-tested guidelines (n=67, 48%) compared with current guidelines (n=26, 20%) (risk ratio: 2.46; 95% CI 1.68 to 3.60). Median simulation completion time was 1.6 min (95% CI 0.2 to 3.0) less with the user-tested guidelines. Participants who used user-tested guidelines reported greater confidence. Conclusion: User-testing injectable medicines guidelines reduces the number of errors and the time taken to prepare and administer intravenous medicines, while increasing staff confidence. Trial registration number: researchregistry5275