An error analysis of probabilistic fibre tracking methods: average curves optimization

Fibre tractography using diffusion tensor imaging is a promising method for estimating the pathways of white matter tracts in the human brain. The success of fibre tracking methods ultimately depends upon the accuracy of the fibre tracking algorithms and the quality of the data. Uncertainty and its representation have an important role to play in fibre tractography methods to infer useful information from real world noisy diffusion weighted data. Probabilistic fibre tracking approaches have received considerable interest recently for resolving orientational uncertainties. In this study, an average curves approach was used to investigate the impact of SNR and tensor field geometry on the accuracy of three different types of probabilistic tracking algorithms. The accuracy was assessed using simulated data and a range of tract geometries. The average curves representations were employed to represent the optimal fibre path of probabilistic tracking curves. The results are compared with streamline tracking on both simulated and in vivo data

Online Learning Models for Content Popularity Prediction In Wireless Edge Caching

Caching popular contents in advance is an important technique to achieve the low latency requirement and to reduce the backhaul costs in future wireless communications. Considering a network with base stations distributed as a Poisson point process (PPP), optimal content placement caching probabilities are derived for known popularity profile, which is unknown in practice. In this paper, online prediction (OP) and online learning (OL) methods are presented based on popularity prediction model (PPM) and Grassmannian prediction model (GPM), to predict the content profile for future time slots for time-varying popularities. In OP, the problem of finding the coefficients is modeled as a constrained non-negative least squares (NNLS) problem which is solved with a modified NNLS algorithm. In addition, these two models are compared with log-request prediction model (RPM), information prediction model (IPM) and average success probability (ASP) based model. Next, in OL methods for the time-varying case, the cumulative mean squared error (MSE) is minimized and the MSE regret is analyzed for each of the models. Moreover, for quasi-time varying case where the popularity changes block-wise, KWIK (know what it knows) learning method is modified for these models to improve the prediction MSE and ASP performance. Simulation results show that for OP, PPM and GPM provides the best ASP among these models, concluding that minimum mean squared error based models do not necessarily result in optimal ASP. OL based models yield approximately similar ASP and MSE, while for quasi-time varying case, KWIK methods provide better performance, which has been verified with MovieLens dataset.Comment: 9 figure, 29 page

Secure Dual-functional Radar-Communication Transmission: Hardware-Efficient Design

This paper investigates the constructive interference (CI) based constant evelope (CE) waveform design problem aiming at enhancing the physical layer (PHY) security in dual-functional radar-communication (DFRC) systems. DFRC systems detect the radar target and communicate with downlink cellular users in wireless networks simultaneously, where the radar target is regarded as a potential eavesdropper which might surveil the data from the base station (BS) to communication users (CUs). The CE waveform and receive beamforming are jointly designed to maximize the signal to interference and noise ratio (SINR) of the radar under the security and system power constraints when the target location is imperfectly known. The optimal solution is obtained by the max-min fractional programming (FP) method. Specifically, the problem is designed to maximize the minimum SINR of the radar in the target location angular interval. Simulation results reveal the effectiveness and the hardware efficiency of the proposed algorithm

The importance of Antarctic krill in biogeochemical cycles

Antarctic krill (Euphausia superba) are swarming, oceanic crustaceans, up to two inches long, and best known as prey for whales and penguins – but they have another important role. With their large size, high biomass and daily vertical migrations they transport and transform essential nutrients, stimulate primary productivity and influence the carbon sink. Antarctic krill are also fished by the Southern Ocean’s largest fishery. Yet how krill fishing impacts nutrient fertilisation and the carbon sink in the Southern Ocean is poorly understood. Our synthesis shows fishery management should consider the influential biogeochemical role of both adult and larval Antarctic krill

Multi-label segmentation of white matter structures: Application to neonatal brains

10.1016/j.neuroimage.2014.08.001NeuroImage102P2913 - 922NEIMEGUSTO (Growing up towards Healthy Outcomes)GUSTO (Growing up towards Healthy Outcomes)GUSTO (Growing up towards Healthy Outcomes

Military moral injury: A concept analysis.

Moral injury is the current term describing the breaching or violation of one's moral code and has gained international research attention due to suicide linkages in military populations (Jamieson et al., Invisible wounds and suicide: Moral injury and veteran mental health. International Journal of Mental Health Nursing, 29, 105-109, 2020). Moral injury's core features are spiritual/existential conflict, shame, guilt and self-condemnation. To date, research focuses on the core features of moral injury and or the nature of events that exposed individuals to moral injury. Walker and Avant (Strategies for Theory Construction in Nursing, Prentice Hall New York, 2011) concept analysis model was used to examine the literature. The aim of this study is to enhance understanding of the defining attributes, antecedents, consequences and empirical referents of moral injury and systematically analyse the concept of moral injury in the context of military members. A literature search was undertaken using specific websites and journals, electronic databases, library catalogues and hand-searches. Concept analysis was used to explicate moral injury, focusing exclusively on use of the concept in the included literature, comparing the terms used over time and across disciplines, and measurement tools for the concept. This concept analysis provides a renewed definition of moral injury in relation to the experience of veterans - 'moral trauma' and defined as: 'the existential, psychological, emotional and or spiritual trauma arising from a conflict, violation or betrayal, either by omission or commission, of or within one's moral beliefs or code(s)'. The analysis will facilitate understanding and operationalization of the concept applied to teaching, learning, practice and research