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Dynamic free-breathing fetal cardiac MRI is one of the most challenging modalities, which requires high temporal and spatial resolution to depict rapid changes in a small fetal heart. The ability of deep learning methods to recover undersampled data could help to optimise the kt-SENSE acquisition strategy and improve non-gated kt-SENSE reconstruction quality. In this work, we explore supervised deep learning networks for reconstruction of kt-SENSE style acquired data using an extensive in vivo dataset. Having access to fully-sampled low-resolution multi-coil fetal cardiac MRI, we study the performance of the networks to recover fully-sampled data from undersampled data. We consider model architectures together with training strategies taking into account their application in the real clinical setup used to collect the dataset to enable networks to recover prospectively undersampled data. We explore a set of modifications to form a baseline performance evaluation for dynamic fetal cardiac MRI on real data. We systematically evaluate the models on coil-combined data to reveal the effect of the suggested changes to the architecture in the context of fetal heart properties. We show that the best-performers recover a detailed depiction of the maternal anatomy on a large scale, but the dynamic properties of the fetal heart are under-represented. Training directly on multi-coil data improves the performance of the models, allows their prospective application to undersampled data and makes them outperform CTFNet introduced for adult cardiac cine MRI. However, these models deliver similar qualitative performances recovering the maternal body very well but underestimating the dynamic properties of fetal heart. This dynamic feature of fast change of fetal heart that is highly localised suggests both more targeted training and evaluation methods might be needed for fetal heart application.

Muscle tissue drives nearly all movement in the animal kingdom, providing power, mobility, and dexterity. Technologies for measuring muscle tissue motion, such as sonomicrometry, fluoromicrometry, and ultrasound, have significantly advanced our understanding of biomechanics. Yet, the field lacks the ability to monitor muscle tissue motion for animal behavior outside the lab. Towards addressing this issue, we previously introduced magnetomicrometry, a method that uses magnetic beads to wirelessly monitor muscle tissue length changes, and we validated magnetomicrometry via tightly-controlled in situ testing. In this study we validate the accuracy of magnetomicrometry against fluoromicrometry during untethered running in an in vivo turkey model. We demonstrate real-time muscle tissue length tracking of the freely-moving turkeys executing various motor activities, including ramp ascent and descent, vertical ascent and descent, and free roaming movement. Given the demonstrated capacity of magnetomicrometry to track muscle movement in untethered animals, we feel that this technique will enable new scientific explorations and an improved understanding of muscle function. -- -- El tejido muscular es el motor de casi todos los movimientos del reino animal, ya que proporciona fuerza, movilidad y destreza. Las tecnolog\'ias para medir el movimiento del tejido muscular, como la sonomicrometr\'ia, la fluoromicrometr\'ia y el ultrasonido, han avanzado considerablemente la comprensi\'on de la biomec\'anica. Sin embargo, este campo carece de la capacidad de rastrear el movimiento del tejido muscular en el comportamiento animal fuera del laboratorio. Para abordar este problema, presentamos previamente la magnetomicrometr\'ia, un m\'etodo que utiliza peque\~nos imanes para rastrear de forma inal\'ambrica los cambios de longitud del tejido muscular, y validamos la magnetomicrometr\'ia mediante pruebas estrechamente controladas in situ. En este estudio validamos la precisi\'on de la magnetomicrometr\'ia en comparaci\'on con la fluoromicrometr\'ia usando un modelo de pavo in vivo mientras corre libremente. Demostramos el rastreo en tiempo real de la longitud del tejido muscular de los pavos que se mueven libremente ejecutando varias actividades motoras, incluyendo el ascenso y el descenso en rampa, el ascenso y el descenso vertical, y el movimiento libre. Dada la capacidad demostrada de la magnetomicrometr\'ia para rastrear el movimiento muscular en animales en un contexto m\'ovil, creemos que esta t\'ecnica permitir\'a nuevas exploraciones cient\'ificas y una mejor comprensi\'on de la funci\'on muscular., Comment: in Spanish language. Translation of the postprint, with the published version in English appended to the end of the PDF. Shared First Authorship: Cameron R. Taylor and Seong Ho Yeon; Shared Senior and Corresponding Authorship: Thomas J. Roberts and Hugh M. Herr

Visual Programming Tools (VPTs) allow users to create interactive media projects such as games and animations using visual representations of programming concepts. Although VPTs have been shown to have huge potential for teaching children with cognitive impairments including those with Autism Spectrum Condition (ASC), research has shown that existing VPTs may not be accessible to them. Therefore, this study proposes a set of recommendations for the design of accessible VPTs for children with ASC. Recommendations were initially gathered and validated by interviewing experts (n=7). The interviews were thematically analysed to identify recommendations. A second set of interviews with a subset of the initial experts (n=3) was then conducted to validate the gathered recommendations. An examination of the available literature was then conducted to identify additional recommendations for the design of VPTs. These recommendations arose from those used for the design of other interactive applications for children with ASC (e.g. virtual environments, serious games) and not identified as part of those the initially gathered from interviews. A novel set of recommendations for the design of VPTs for children with ASC and additional cognitive impairments has been defined as the result of this study.

In in-utero MRI, motion correction for fetal body and placenta poses a particular challenge due to the presence of local non-rigid transformations of organs caused by bending and stretching. The existing slice-to-volume registration (SVR) reconstruction methods are widely employed for motion correction of fetal brain that undergoes only rigid transformation. However, for reconstruction of fetal body and placenta, rigid registration cannot resolve the issue of misregistrations due to deformable motion, resulting in degradation of features in the reconstructed volume. We propose a Deformable SVR (DSVR), a novel approach for non-rigid motion correction of fetal MRI based on a hierarchical deformable SVR scheme to allow high resolution reconstruction of the fetal body and placenta. Additionally, a robust scheme for structure-based rejection of outliers minimises the impact of registration errors. The improved performance of DSVR in comparison to SVR and patch-to-volume registration (PVR) methods is quantitatively demonstrated in simulated experiments and 20 fetal MRI datasets from 28-31 weeks gestational age (GA) range with varying degree of motion corruption. In addition, we present qualitative evaluation of 100 fetal body cases from 20-34 weeks GA range.

We examine the temperature dependence of the magnetic ordering in the frustrated Heisenberg $J_1-J_2$ model in presence of two different kind of dopants: vacancies or magnetic impurities. We demonstrate that, irrespective to their magnetic ratio, the introduction of impurities quenches the order by disorder selection mechanism associated with an Ising-like phase transition at low temperatures and gives way to a $90^\circ$ (anticollinear) order . The presence of dopants triggers a non trivial competition between entropically selected states (collinear) and energetically favoured ones (anticollinear) in dependence of both dilution and temperature. While in case of magnetic impurity, the interesting magnetic phases are observed for full range of temperature and doping, in case of nonmagnetic impurities every magnetic order is destroyed at all temperatures above $12\%$ dilution. At fixed low temperature and tuning the doping we show a first order phase transition leading to the re-entrance of the Ising-like order with percolation of islands of $90^\circ$ order. At fixed doping and varying the temperature we observe a transition from the anticollinear to the collinear phase assisted by a new emerging magnetic phase in the presence of magnetic impurities, whilst in case of vacancies this transition is characterised by a coexistent region of both. Furthermore, tuning the magnetic moment of the impurities, a complete collapse of the Ising-like order is attained. This is in agreement with observations of Ir dopant atoms in superconducting Ba(Fe$_{1-x}$Ir$_x$)$_2$As$_2$ with $x<0.047$.