The Marginal Cost of Frailty Among Medicare Patients on Hemodialysis.

Introduction:Dialysis patients incur disproportionately high costs compared with other Medicare beneficiaries. Care for frail individuals may be even more costly. We examined the extent to which frailty contributes to higher costs among dialysis patients. Methods:We used ACTIVE/ADIPOSE (A Cohort to Investigate the Value of Exercise/Analyses Designed to Investigate the Paradox of Obesity and Survival in ESRD) enrollees (adult hemodialysis patients evaluated from June 2009 to August 2011) in a retrospective cohort analysis. Individuals using Medicare as the primary payer were included. Fried's frailty phenotype was evaluated at baseline, 12, and 24 months. Costs were derived from linkage with the US Renal Data System (USRDS) and Medicare claims data. We used generalized estimating equations (GEEs) incorporating time-updated frailty and costs to evaluate adjusted point estimates and the marginal cost associated with being frail. We also investigated if frail patients who died during the study incurred higher costs than those who survived. Results:Among 771 enrollees in ACTIVE/ADIPOSE, 425 met inclusion criteria. Mean age was 56 ± 13 years, body mass index (BMI) 29.2 ± 7.1 kg/m2, 42.4% were women, and 29.0% were frail at baseline. Over a mean follow-up of 2.3 years, frail individuals incurred 22% (95% confidence interval [CI] 9.6%-35.8%) higher costs compared with nonfrail individuals ($87,600 per patient per year [pppy], 95$71,800 pppy, 95% CI 64,800-79,600), the difference was driven primarily by higher inpatient expenditures. The difference between frail and nonfrail patients' inpatient expenditures was even more pronounced among those who died during the study compared with those who survived. Conclusions:Frail dialysis patients incur a significantly higher cost relative to their nonfrail counterparts, primarily driven by higher inpatient costs. Frail patients near end of life incur even higher costs

Energetic Extremes in Aquatic Locomotion by Coral Reef Fishes

Underwater locomotion is challenging due to the high friction and resistance imposed on a body moving through water and energy lost in the wake during undulatory propulsion. While aquatic organisms have evolved streamlined shapes to overcome such resistance, underwater locomotion has long been considered a costly exercise. Recent evidence for a range of swimming vertebrates, however, has suggested that flapping paired appendages around a rigid body may be an extremely efficient means of aquatic locomotion. Using intermittent flow-through respirometry, we found exceptional energetic performance in the Bluelined wrasse Stethojulis bandanensis, which maintains tuna-like optimum cruising speeds (up to 1 metre s(-1)) while using 40% less energy than expected for their body size. Displaying an exceptional aerobic scope (22-fold above resting), streamlined rigid-body posture, and wing-like fins that generate lift-based thrust, S. bandanensis literally flies underwater to efficiently maintain high optimum swimming speeds. Extreme energetic performance may be key to the colonization of highly variable environments, such as the wave-swept habitats where S. bandanensis and other wing-finned species tend to occur. Challenging preconceived notions of how best to power aquatic locomotion, biomimicry of such lift-based fin movements could yield dramatic reductions in the power needed to propel underwater vehicles at high speed.Funding was provided by the Australian Research Council (to CJF) and the Danish Agency for Science, Technology and Innovation (to JFS). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript

Bayesian model comparison for compartmental models with applications in positron emission tomography

We develop strategies for Bayesian modelling as well as model comparison, averaging and selection for compartmental models with particular emphasis on those that occur in the analysis of positron emission tomography (PET) data. Both modelling and computational issues are considered. Biophysically inspired informative priors are developed for the problem at hand, and by comparison with default vague priors it is shown that the proposed modelling is not overly sensitive to prior specification. It is also shown that an additive normal error structure does not describe measured PET data well, despite being very widely used, and that within a simple Bayesian framework simultaneous parameter estimation and model comparison can be performed with a more general noise model. The proposed approach is compared with standard techniques using both simulated and real data. In addition to good, robust estimation performance, the proposed technique provides, automatically, a characterisation of the uncertainty in the resulting estimates which can be considerable in applications such as PET

Peripheral Neurons Depend on CNS-Derived Guidance Cues for Proper Navigation during Leech Development

AbstractIn leech, major nerve pathways are pioneered by CNS neurons and evidence from dye-injection and antibody experiments suggest that they may serve as guides for later differentiating neurons. In this study we have directly tested this hypothesis by examining the consequences of CNS ablation on the navigation in the periphery of a well-defined population of afferent sensory neurons. We show that in the absence of CNS-derived axons the axonal growth cones of this population of peripheral neurons extend with little directionality and instead of forming orderly projections, default into forming circular fasciculated pathways with each other. This suggests that CNS-derived guidance cues are absolutely required for the correct navigation of these peripheral sensory neurons

Managing disorganization in a disaster case

This thesis has five main goals. The first goal is to attempt to replicate the system dynamics model “The essence of transformation in a selforganizing team“ by Tu et al, with the modelling tool Vensim. “The essence of transformation in a selforganizing team“ deals with managing disorganizing using imperical data from the Palau Case. The other four goals include a review of Tu et al.’s model, implementing proposals for improvement, expressing the implications for the model for better crisis management, and if real data can be found describe a different case of emergency management. We approached this problem by reviewing and testing Tu et al.’s iThink model, and replicated it into a Vensim model. The equations were tested and applied the correct unit and polarity. The model was also simplified by removing unnecessary equations and the model was applied to a new crisis case (Hatlestad case). Our results show that our simplified model can be used in disaster planning, with only minor changes to the variables other disaster cases where the situation goes from chaos to control can be modelled

Dynamic filtering of static dipoles in magnetoencephalography

We consider the problem of estimating neural activity from measurements of the magnetic fields recorded by magnetoencephalography. We exploit the temporal structure of the problem and model the neural current as a collection of evolving current dipoles, which appear and disappear, but whose locations are constant throughout their lifetime. This fully reflects the physiological interpretation of the model. In order to conduct inference under this proposed model, it was necessary to develop an algorithm based around state-of-the-art sequential Monte Carlo methods employing carefully designed importance distributions. Previous work employed a bootstrap filter and an artificial dynamic structure where dipoles performed a random walk in space, yielding nonphysical artefacts in the reconstructions; such artefacts are not observed when using the proposed model. The algorithm is validated with simulated data, in which it provided an average localisation error which is approximately half that of the bootstrap filter. An application to complex real data derived from a somatosensory experiment is presented. Assessment of model fit via marginal likelihood showed a clear preference for the proposed model and the associated reconstructions show better localisation

Nordic research in logistics and supply chain management: an empirical analysis

Purpose – The purpose of this data-based analysis is to report and reflect on the characteristics of the academic discipline concerned with logistics and supply chain management (SCM) as it is conducted in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden). The paper further seeks to explain variations in the research field in terms of the demographics, research domains and methodologies, and publication patterns of the study’s respondents. Design/methodology/approach – An e-mail questionnaire survey was distributed to 353 researchers based in the Nordic countries. With 144 answers returned, the response rate was 41 per cent. Findings – The study did not provide a clear picture of a distinct Nordic research paradigm applying to the study of logistics and SCM. The analysis shows as characteristic of research issues pursued by Nordic researchers the focus on supply chains and networks and the use of dyads, chains or networks of organizations as levels of analysis. The use of case study methodology and a highly diversified publication pattern were likewise evident. Most researchers were found to rely heavily on external research funding. Significant differences were also identified for research conducted by researchers holding PhD degrees as compared to research by respondents with lower degrees, for researchers affiliated with institutions based in the technical sciences in comparison to those in the social sciences, and for institutions according to their varying degrees of experience with research in the field and external funding. Research limitations/implications – The research reported here may help individual researchers raise their consciousness about their own research. Originality/value – This is the first empirical study to analyze research paradigms within logistics and SCM in the Nordic countries. It identifies a number of significant differences in regard to research patterns among various categories of researchers and institutions