Bayesian inference and model choice in a hidden stochastic two-compartment model of hematopoietic stem cell fate decisions

Despite rapid advances in experimental cell biology, the in vivo behavior of hematopoietic stem cells (HSC) cannot be directly observed and measured. Previously we modeled feline hematopoiesis using a two-compartment hidden Markov process that had birth and emigration events in the first compartment. Here we perform Bayesian statistical inference on models which contain two additional events in the first compartment in order to determine if HSC fate decisions are linked to cell division or occur independently. Pareto Optimal Model Assessment approach is used to cross check the estimates from Bayesian inference. Our results show that HSC must divide symmetrically (i.e., produce two HSC daughter cells) in order to maintain hematopoiesis. We then demonstrate that the augmented model that adds asymmetric division events provides a better fit to the competitive transplantation data, and we thus provide evidence that HSC fate determination in vivo occurs both in association with cell division and at a separate point in time. Last we show that assuming each cat has a unique set of parameters leads to either a significant decrease or a nonsignificant increase in model fit, suggesting that the kinetic parameters for HSC are not unique attributes of individual animals, but shared within a species.Comment: Published in at http://dx.doi.org/10.1214/09-AOAS269 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

Designing to increase user acceptance of respiratory protection

None provided

We Are Family: Exploring Sense of Community for College Students With and Without Hidden Disabilities

The purpose of this study was to explore the four factors of sense of community and to establish if there is a difference in the sense of community for students with and without hidden disabilities. A quantitative survey was conducted in a cross-sectional format, measuring responses during the spring semester of the academic year at a small, private, liberal arts college in Western New York State with approximately 2,600 undergraduate students. The data revealed that, overall, students experienced all four factors of sense of community: needs, membership, influence, and connection. The results indicate that in the areas of reinforcement of needs, membership, and overall sense of community, students who did not have hidden disabilities experienced a higher sense of community than students who identified themselves as having a hidden disability. In the areas of influence and connection, there was no statistically significant difference between those students with hidden disabilities and their nondisabled peers. Consideration for future research would be to conduct this study at other colleges and universities across the country to get a greater sample of students, consider research-based strategies to provide supports through universal design, and, develop a way to collect data on sense of community for new students throughout the first year in a program of study. By tracking students who are new to the campus, staff could determine if further supports are needed for groups of students. By establishing a connection with students who may be struggling, colleges can increase the chances that students will begin to feel their needs are being met

An integrated and dynamic framework for assessing sustainable resilience in complex adaptive systems

Growing awareness of climate change and resulting impacts to communities have generated increasing interest in understanding relationships between vulnerability, resilience, sustainability, and adaptive capacity, and how these concepts can be combined to better assess the quality of complex adaptive systems over time. Previous work has described interactions between these concepts and the value-added should they be integrated and applied in a strategic manner, resulting in a new understanding of system quality defined as sustainable resilience. However, a framework for explicitly integrating vulnerability, resilience, and sustainability assessment to develop understanding of system sustainable resilience has yet to be proposed. This paper presents a high-level, integrated and dynamic framework for assessing sustainable resilience for complex adaptive systems. We provide a set of functional definitions, a description of each step in the proposed assessment process, and walk through an example application of the framework, including a discussion of preliminary analyses, technical methodologies employed, and suggested future advances

Agent-Based Model of Navigable Inland Waterway Tow Operation Procedures

Transportation modeling within the context of extreme weather events induced by climate change is critical to understand and improve the resilience of transport systems as the world moves further into the 21st century. Among transportation modes, navigable inland waterways in particular face severe challenges to their future reliability as a result of extreme weather events. The economic implications of inland waterway operational efficiencies on commercial shipping have been studied in detail for several decades. Less well understood, however, are the effects of tow operation procedures enacted during adverse river conditions that have resulted from extreme weather events. This paper describes a model of a waterway segment that simulates stakeholder decision making and tow operator behavior to provide stakeholders with insights into the possible benefits of waterway action plans as operational guidance documents. Simulations run for a test area of the navigable inland waterway system indicated that operational procedures recommended in waterway action plans might have a significant impact on waterway operational efficiencies, which suggests that the model may be a useful decision-support tool for waterway stakeholders

An integrative approach to conceptualizing sustainable resilience

Vulnerability, resilience, and sustainability are three concepts commonly used in assessing the quality of a variety of systems. While each can be applied independently when performing risk analysis, there is growing interest across multiple disciplines in understanding how these concepts can be integrated when considering complex adaptive systems, such as communities. In this paper, we identify issues related to the use of these respective concepts in assessing complex adaptive systems, and describe how these issues may produce imbalanced results and maladaptive outcomes. We identify five critical areas where alignment and integration across concepts can lead to improved system assessment. As a result, we introduce a new paradigm, sustainable resilience, in which these concepts are integrated to enable alignment of adaptation and transformation strategies with desired resilience outcomes. This work provides the foundation for the development of an integrated assessment framework to help guide informed risk-based decisionmaking for sustainable and resilient systems

Designing a Support System for College Students with ADD/ADHD/Executive Functioning Disorders

The purpose of this paper is to describe ways to support college students with disabilities on a college campus through the lens of Bolman and Deal’s (2013) Four Frames, and then identify potential strategies instructors can use to assist students in coping with the increasing demands made of him or her in a college setting

Modeling and Experimental Testing of an Unmanned Surface Vehicle with Rudderless Double Thrusters.

Motion control of unmanned surface vehicles (USVs) is a crucial issue in sailing performance and navigation costs. The actuators of USVs currently available are mostly a combination of thrusters and rudders. The modeling for USVs with rudderless double thrusters is rarely studied. In this paper, the three degrees of freedom (DOFs) dynamic model and propeller thrust model of this kind of USV were derived and combined. The unknown parameters of the propeller thrust model were reduced from six to two. In the three-DOF model, the propulsion of the USV was completely provided by the resultant force generated by double thrusters and the rotational moment was related to the differential thrust. It combined the propeller thrust model to represent the thrust in more detail. We performed a series of tests for a 1.5 m long, 50 kg USV, in order to obtain the model parameters through system identification. Then, the accuracy of the modeling and identification results was verified by experimental testing. Finally, based on the established model and the proportional derivative+line of sight (PD+LOS) control algorithm, the path-following control of the USV was achieved through simulations and experiments. All these demonstrated the validity and practical value of the established model

Allometric Scaling of the Active Hematopoietic Stem Cell Pool across Mammals

BACKGROUND: Many biological processes are characterized by allometric relations of the type Y = Y (0) M(b) between an observable Y and body mass M, which pervade at multiple levels of organization. In what regards the hematopoietic stem cell pool, there is experimental evidence that the size of the hematopoietic stem cell pool is conserved in mammals. However, demands for blood cell formation vary across mammals and thus the size of the active stem cell compartment could vary across species. METHODOLOGY/PRINCIPLE FINDINGS: Here we investigate the allometric scaling of the hematopoietic system in a large group of mammalian species using reticulocyte counts as a marker of the active stem cell pool. Our model predicts that the total number of active stem cells, in an adult mammal, scales with body mass with the exponent ¾. CONCLUSION/SIGNIFICANCE: The scaling predicted here provides an intuitive justification of the Hayflick hypothesis and supports the current view of a small active stem cell pool supported by a large, quiescent reserve. The present scaling shows excellent agreement with the available (indirect) data for smaller mammals. The small size of the active stem cell pool enhances the role of stochastic effects in the overall dynamics of the hematopoietic system