Stroke disease places a heavy burden on society, incurring long periods of hospital and community care. Also stroke is a highly complex disease with heterogeneous outcomes and multiple strategies for therapy and care. In this article we develop a modeling framework that clusters patients with respect to their length of stay (LOS); phase-type models are then used to describe patient flows for each cluster. In most cases, there are multiple outcomes, such as discharge to normal residence, nursing home, or death. We therefore derive a novel analytical model for the distribution of LOS in such situations. A model of the whole care system is developed, based on Poisson admissions to hospital, and results obtained for expected numbers in different states of the system at any time. We can thus describe the whole integrated system of stroke patient care, which will facilitate planning of services. We also use the basic model to build a discrete-event simulation, which incorporates back-up queues to model delayed discharge. Based on stroke patients' data from the Belfast City Hospital, various scenarios are explored with a focus on the potential efficiency gains if LOS, prior to discharge to a private nursing home, can be reduced. Predictions for bed occupancy are also provided. The overall modeling framework characterizes the behavior of stroke patient populations, with a focus on integrated system-wide planning, encompassing hospital and community services. Within this general framework we can develop either analytic or simulation models that take account of patient heterogeneity and multiple care options. ACM Reference Format:McClean, S., Barton, M., Garg, L., Fullerton, K. 2011. A modeling framework that combines Markov models and discrete-event simulation for stroke patient care. ACM Trans. Model. Comput.

Electroencephalographic (EEG) source localization is an important tool for noninvasive study of brain dynamics, due to its ability to probe neural activity more directly, with better temporal resolution than other imaging modalities. One promising technique for solving the EEG inverse problem is Kalman filtering, because it provides a natural framework for incorporating dynamic EEG generation models in source localization. Here, a recently developed inverse solution is introduced, which uses spatiotemporal Kalman filtering tuned through likelihood maximization. Standard diagnostic tests for objectively evaluating Kalman filter performance are then described and applied to inverse solutions for simulated and clinical EEG data. These tests, employed for the first time in Kalman-filter-based source localization, check the statistical properties of the innovation and validate the use of likelihood maximization for filter tuning. However, this analysis also reveals that the filter's existing space- and time-invariant process model, which contains a single fixed-frequency resonance, is unable to completely model the complex spatiotemporal dynamics of EEG data. This finding indicates that the algorithm could be improved by allowing the process model parameters to vary in space.

No abstract

Omega-3 polyunsaturated fatty acids (PUFAs) exert an anticancer effect by affecting multiple cellular mechanisms leading to inhibition of proliferation and induction of apoptosis. It is well known that breast cancer comprises distinct molecular subtypes which differ in their responsiveness to therapeutic and preventive agents. We tested the hypothesis that n-3FA may preferentially affect triple-negative breast cancer cells for which no targeted intervention is presently available. The in vitro antiproliferative effects of n-3 PUFA docosahexaenoic acid (DHA) and its metabolite, 4-OH-DHA as well as its putative metabolite 4-OXO-DHA, were tested in five triple-negative human basal breast cell lines at different stages of transformation (MCF-10F, trMCF, bsMCF, MDA-MB-231, and BT-549) and three luminal breast cancer cell lines (MCF-7, T-47D, and SK-BR-3). Cell proliferation was measured with the tetrazolium MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay. DHA and its oxidized derivatives significantly inhibited cell proliferation (20–90% reduction) of both basal and luminal breast cancer cell lines. The inhibitory effect was more pronounced on triple-negative basal breast cancer cell lines as compared to luminal breast cancer cell lines after 4-OXO-DHA treatment. Our data provide novel information regarding the preferential antitumor effect of oxidized derivatives of DHA on basal type breast cancer.

No abstract