Model Reduction on the Wnt Pathway Leads to Biological Adaptation

Complex systems are an unavoidable problem in the field of biology. One of the ways that scientists have tried to overcome this problem is by building mathematical models—manageable representations designed to look at specific physical phenomena. The Wnt Signaling Pathway is a complex system known to regulate cell-to-cell interactions, play a crucial role in Embryonic Development, and has been implicated in the study of cancer. Typically, the Wnt signal is observed through the behavior of a protein called beta-Catenin (β-Catenin). In 2003, Lee et al. built a model of the Wnt pathway which caused β-Catenin to increase over time. However, in 2010, Jensen et al. built a different model of the Wnt pathway which caused β-Catenin to oscillate over time. This project called for model reduction on the Jensen et al. model to identify the phenomenological parameter combinations that determined features of the Wnt oscillations. The method used to reduce the model is called the Manifold Boundary Approximation Method, which is a geometric, parameter-independent method of reducing the model one parameter at a time. Reduction of the model showed that there were 5 variables and 8 parameters which drove the oscillating behavior of the system. After comparing our results to the Lee et al. reduced model of the Wnt pathway done by student Dane Bjork, a minimal model was constructed which predicted a novel class behavior of the Wnt system: biological adaptation

The Effects of Conceptual Processing Versus Suppression on Analogue PTSD Symptoms after a Distressing Film

Abstract BACKGROUND: Researchers have begun to scrutinize the assumption that active processing in response to a traumatic event is beneficial whereas avoidance of thoughts, emotions and reminders about the traumatic event is detrimental. Indications that avoidance is not always detrimental come from studies on grief and debriefing. AIMS: In an analogue experimental study, the hypothesis was tested that conceptually-driven processing immediately after a distressing film is more successful in reducing analogue PTSD symptoms than suppression of thoughts and images related to the film. METHOD: Ninety students watched a distressing film after which they were instructed to either elaborate on the meaning of the film (conceptual processing) (n = 31), suppress all thoughts and images of the film by performing a task (n = 29), or were given no instruction (n = 30). Four hours later, analogue PTSD symptoms were assessed. RESULTS: The results showed that conceptually-driven processing does not result in fewer analogue PTSD symptoms than suppression. CONCLUSIONS: It is speculated that suppression may only be dysfunctional when individuals interpret their symptoms negatively or when suppression is believed to be dysfunctional

Societal preferences for standard health insurance coverage in the Netherlands: a cross-sectional study

INTRODUCTION: Cost-effectiveness is an important criterion in the decision to cover interventions in health insurance packages. One of the outcome measures, the quality-adjusted life year, has been criticised on its assumptions and implications concerning life expectancy and quality of life. Several studies have been conducted that measured societal preferences concerning healthcare rationing decisions. These studies mainly focused on one attribute. To adjust quality-adjusted life year maximisation in accordance with societal preferences, the relative importance of attributes should be studied. The present study aims to measure the relative importance of age, gender, socioeconomic status, pre-intervention health state, treatment effect, chance of treatment success and number of people in need of the intervention. A secondary objective is to compare the validity of the willingness to pay method with the validity of a relatively new preference elicitation method, best-worst scaling. METHODS AND ANALYSIS: A representative sample of 2000 Dutch citizens, over 18 years of age, are recruited to complete a web-based survey containing treatment scenarios. The scenarios present different levels of attributes. Respondents are asked to select one of the four scenarios that they prefer to be covered by the Dutch standard health insurance package and one that they prefer not to be covered. They are also asked to indicate how much they are willing to pay for each treatment scenario. At the end of the survey, respondents are asked to rate every attribute on a 1-10 scale. Two versions of the questionnaire are developed which differ on the framing, that is, treatments can be added to or removed from the insurance package. The data will be analysed by means of sequential conditional logit analysis (best-worst scaling) and analysis of variance (willingness to pay). ETHICS AND DISSEMINATION: The protocol is reviewed and approved by the medical ethical committee of the University Medical Center Leiden.Medical Decision MakingAnalysis and support of clinical decision makin

Mode-dependent Loss and Gain Emulation in Coupled SDM Transmission

Space-division multiplexing (SDM) is currently the only solution to cope with the exponential growth of data traffic in optical transmission networks. The performance of long-haul SDM transmission is fundamentally limited by mode-dependent loss (MDL) and mode-dependent gain (MDG) generated in components and amplifiers. To enable the study of MDL/MDG effects in SDM systems as well as MDL/MDG estimation methods within the context of experimental setups, we evaluate an MDL/MDG emulator based on variable optical attenuators (VOAs) and photonic lanterns. We assess MDL/MDG emulation in different attenuation scenarios and demonstrate the capability of the emulator to artificially introduce a wide range of MDL/MDG in a short-reach 3-mode transmission system