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Lot-to-lot verification is an integral component for monitoring the long-term stability of a measurement procedure. The practice is challenged by the resource requirements as well as uncertainty surrounding experimental design and statistical analysis that is optimal for individual laboratories, although guidance is becoming increasingly available. Collaborative verification efforts as well as application of patient-based monitoring are likely to further improve identification of any differences in performance in a relatively timely manner. Appropriate follow up actions of failed lot-to-lot verification is required and must balance potential disruptions to clinical services provided by the laboratory. Manufacturers need to increase transparency surrounding release criteria and work closer with laboratory professionals to ensure acceptable reagent lots are released to end users. A tripartite collaboration between regulatory bodies, manufacturers, and laboratory medicine professional bodies is key to developing a balanced system where regulatory, manufacturing, and clinical requirements of laboratory testing are met, to minimize differences between reagent lots and ensure patient safety. Clinical Chemistry and Laboratory Medicine has served as a fertile platform for advancing the discussion and practice of lot-to-lot verification in the past 60 years and will continue to be an advocate of this important topic for many more years to come. [ABSTRACT FROM AUTHOR]

Equipment replacement strategies are highly dependent on the horizon of analysis. While the literature can generally be categorized according to infinite or finite-horizon solutions, this paper examines the case where the horizon will last at least [T.sub.s] periods but may last as long as [T.sub.1] periods, due to uncertainty in the length of production runs or the temporary provision of services. Stochastic dynamic programming formulations are presented and solutions that minimize either expected costs or maximum regret are explored. Furthermore, the critical time period where optimal decisions diverge for different horizon realizations is identified. As this time period may be substantially earlier than [T.sub.s], a lease option contract is designed that allows owners to lower the risk of high costs that may result from a given horizon realization, while opening a possible source of revenue for a leasor. Keywords: Dynamic programming, life cycle models., 1. Introduction Equipment replacement analysis is concerned with identifying the length of time to retain an asset and its replacements over some designated horizon of analysis such that capital and [...]

With the growing need to guide decision-making in today's complex managerial environment, researchers of the Operations Research/Management Science community have shown a considerable interest in modelling complex managerial systems using the agent-based modelling and simulation technique. This paper presents an estimation-and-optimisation (ESTOPT) architecture to simulate an agent's decision-making process in black-box managerial environment. An ESTOPT agent's behaviour is considered as a two-stage process of solving its optimisation problem, some parameters of which are uncertain and need to be estimated. In the first stage, the agent collects and records information for estimation; in the next stage, it attempts to solve the optimisation problem. The solution guides the agent's actions on the environment which, in turn, provides the agent with new information and payoff as feedback. In this paper, two agent-based models are introduced to demonstrate the implementation of the ESTOPT approach. The simulation outcomes compare favourably with both empirical and theoretical results, suggesting that the ESTOPT approach can be used to simulate an agent's decision-making process in black-box managerial environment. [ABSTRACT FROM AUTHOR]

Age-related declines in cognition are associated with widespread structural and functional brain changes, including changes in resting-state functional connectivity and gray and white matter status. Recently we have shown that the elasticity of cerebral arteries also explains some of the variance in cognitive and brain health in aging. Here, we investigated how network segregation, cerebral arterial elasticity (measured with pulse-DOT—the arterial pulse based on diffuse optical tomography) and gray and white matter status jointly account for age-related differences in cognitive performance. We hypothesized that at least some of the variance in brain and cognitive aging is linked to reduced cerebrovascular elasticity, leading to increased cortical atrophy and white matter abnormalities, which, in turn, are linked to reduced network segregation and decreases in cognitive performance. Pairwise comparisons between these variables are consistent with an exploratory hierarchical model linking them, especially when focusing on association network segregation (compared with segregation in sensorimotor networks). These findings suggest that preventing or slowing age-related changes in one or more of these factors may induce a neurophysiological cascade beneficial for preserving cognition in aging.

Introduction: A product recall was issued for the Roche/Hitachi Cobas Gentamicin II assays on 25 th May 2016 in Australia, after a 15 - 20% positive analytical shift was discovered. Laboratories were advised to employ the Thermo Fisher Gentamicin assay as an alternative. Following the reintroduction of the revised assay on 12 th September 2016, a second reagent recall was made on 20 th March 2017 after the discovery of a 20% negative analytical shift due to erroneous instrument adjustment factor., Materials and Methods: The practices of an index laboratory were examined to determine how the analytical shifts evaded detection by routine internal quality control (IQC) and external quality assurance (EQA) systems. The ability of the patient result-based approaches, including moving average (MovAvg) and moving sum of outliers (MovSO) approaches in detecting these shifts were examined., Results: Internal quality control data of the index laboratory were acceptable prior to the product recall. The practice of adjusting IQC target following a change in assay method resulted in the missed negative shift when the revised Roche assay was reintroduced. While the EQA data of the Roche subgroup showed clear negative bias relative to other laboratory methods, the results were considered as possible 'matrix effect'. The MovAvg method detected the positive shift before the product recall. The MovSO did not detect the negative shift in the index laboratory but did so in another laboratory 5 days before the second product recall., Conclusions: There are gaps in current laboratory quality practices that leave room for analytical errors to evade detection., Competing Interests: Potential conflict of interest: None declared.