A comparative study of flows through funnel-shaped bottlenecks placed in the middle and corner

Upon exiting buildings, theatres, and stadiums, which house a great number of people, egress points can act as bottlenecks, resulting in crowded exits and decreased flows. Most studies investigating flow have been conducted in either narrow bottlenecks (doors) or funnel shape bottlenecks, with the latter investigating bottlenecks placed in the middle of the walkway. This study investigates, for the first time, crowd flow through funnel-shaped bottlenecks placed in the corner of the walkway and makes comparisons with similar bottlenecks of the same length, entrance and exit width placed in the middle of the walkway. The entry width and exit width of the bottlenecks were 3 m and 1 m respectively, with lengths varying from 1 m to 4 m; they continued into a 10 m corridor. Ninety-four participants of various ages were observed moving through each of the configurations. The results indicated that using funnel-shaped bottlenecks in the middle of the walkway increased the flow rate significantly compared to the corner in bottlenecks with 2 m and 3 m lengths. This is contrary to what some other researchers have found for narrow bottlenecks placed in the middle and corner of a wall, although it is recognised that the configuration of funnel-shaped bottlenecks makes the comparison more complex and further work is required in this area. Notwithstanding these results are considered valuable for consideration when designing egress points and corridors in complex buildings such as metro and train stations

Biomaterials‐Based Approaches to Tumor Spheroid and Organoid Modeling

Evolving understanding of structural and biological complexity of tumors has stimulated development of physiologically relevant tumor models for cancer research and drug discovery. A major motivation for developing new tumor models is to recreate the 3D environment of tumors and context‐mediated functional regulation of cancer cells. Such models overcome many limitations of standard monolayer cancer cell cultures. Under defined culture conditions, cancer cells self‐assemble into 3D constructs known as spheroids. Additionally, cancer cells may recapitulate steps in embryonic development to self‐organize into 3D cultures known as organoids. Importantly, spheroids and organoids reproduce morphology and biologic properties of tumors, providing valuable new tools for research, drug discovery, and precision medicine in cancer. This Progress Report discusses uses of both natural and synthetic biomaterials to culture cancer cells as spheroids or organoids, specifically highlighting studies that demonstrate how these models recapitulate key properties of native tumors. The report concludes with the perspectives on the utility of these models and areas of need for future developments to more closely mimic pathologic events in tumors.State‐of‐the‐art approaches using natural, synthetic, and composite biomaterials for 3D tumor modeling are presented in this Progress Report. Furthermore, it is discussed how these models uniquely reproduce key properties of native tumors to facilitate basic and applied cancer research and cancer drug discovery efforts.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142941/1/adhm201700980.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142941/2/adhm201700980-sup-0001-S1.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142941/3/adhm201700980_am.pd

High Throughput, Polymeric Aqueous Two‐Phase Printing of Tumor Spheroids

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109304/1/adfm201401302-sup-0001-S1.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/109304/2/adfm201401302.pd

Microprinted feeder cells guide embryonic stem cell fate

We introduce a non‐contact approach to microprint multiple types of feeder cells in a microarray format using immiscible aqueous solutions of two biopolymers. Droplets of cell suspension in the denser aqueous phase are printed on a substrate residing within a bath of the immersion aqueous phase. Due to their affinity to the denser phase, cells remain localized within the drops and adhere to regions of the substrate underneath the drops. We show the utility of this technology for creating duplex heterocellular stem cell niches by printing two different support cell types on a gel surface and overlaying them with mouse embryonic stem cells (mESCs). As desired, the type of printed support cell spatially direct the fate of overlaid mESCs. Interestingly, we found that interspaced mESCs colonies on differentiation‐inducing feeder cells show enhanced neuronal differentiation and give rise to dense networks of neurons. This cell printing technology provides unprecedented capabilities to efficiently identify the role of various feeder cells in guiding the fate of stem cells. Biotechnol. Bioeng. 2011;108: 2509–2516. © 2011 Wiley Periodicals, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/86949/1/23190_ftp.pd

Experimental Analyses of Step Extent and Contact Buffer in Pedestrian Dynamics

This study aims to quantify and develop a deeper understanding of the parameters that underpin the development of a new, predictive, microscopic model of pedestrian movement with the potential to accurately reflect the complexity of flow dynamics now and into the future. It presents the results and analyses of two single file experiments designed to quantify the physical space taken up by the extent of a person's stepping movement (maximum step extent) and the minimum distance between points of inter-person contact (contact buffer) across a range of walking speeds. The experiments successfully used high-resolution optical motion capture and enhanced video analysis to quantify the dynamic changes in gait and spatial parameters, which were manifested as overlapping steps, and changes to step extent, step length, step frequency, and contact distance. The sum of the step extent and contact buffer, at different speeds, was found to be within a few centimetres of the inter-person distance (headway), leading to the conclusion that these parameters are therefore key components for the derivation of inter-person spacing and, hence, overall crowd movement. The work informs the longer term aim of developing the mathematical model which has the potential to include pedestrian demographics, walking ability and cognitive capabilities

Serum anti-hsp27 antibodies concentration in diabetes mellitus; population based case-control study

Background: Diabetes mellitus is an important risk factor for cardiovascular disease. Different biomarkers have been investigated for the diagnosis of diabetes pathogenesis or its complications. There are also reports regarding an increased level of anti-HSP27 antibodies in atherogenesis. We aimed to evaluate serum anti-heat shock protein 27 antibodies level in subjects with diabetes mellitus and undiagnosed individuals.  Materials and Methods: This cross-sectional study was conducted on 6447 MASHAD study subjects, including four groups with diabetes mellitus (n=610), undiagnosed diabetes (n=162), impaired fasting glucose (IFG) (n=619) and normal (n=5056) subjects. Demographic and anthropometric data were obtained from all participants. Fasting serum glucose (FSG) and other parameters were measured. In-house enzyme-linked immune sorbent assay method was used for measuring Anti-HSP27 antibodies levels. Results: There were significant differences in weight (p=0.034), body mass index, waist, and hip circumference, systolic and diastolic blood pressure, fasting serum glucose, lipid profile and high sensitive- C reactive protein (p<0.001) between four groups of diabetes mellitus, undiagnosed diabetes, impaired fasting glucose, and normal subjects. The serum anti-HSP27 antibody titer did not show a significant difference between studied groups. Conclusion: Serum antibody titers to HSP27 were not significantly different between four groups categorized based on their FSG levels in a large population

Internally-consistent estimation of dynamic network origin-destination flows from intelligent transportation systems data using bi-level optimization

textDeployment of Intelligent Transportation Systems (ITS) is providing researchers and practitioners with an unprecedented amount of valuable on-line and archived traffic data. To date, ITS data have been used primarily to support real-time operational applications, while other potential uses of these data have been largely ignored. In this research, the effort to extract knowledge from the on-line or archived data gathered by Advanced Transportation Management Systems (ATMS) is focused on the estimation of dynamic origin-destination (OD) flows using optimization methods. In addition to their use for planning purposes, time-dependent OD flows can be used as an input to Dynamic Traffic Assignment (DTA) systems. However, gathering OD demand flow information directly by conducting surveys is very costly and time consuming. To estimate the OD flows, a methodology is developed to minimize an overall measure of the deviation of estimated link-flows from the time-varying link-flow observations, subject to a set of constraints. The set of constraints could include nonnegativity constraints, initial condition constraints, cordon line counts and the user’s route-choice behavior or traffic assignment rules. The traffic assignment solution, itself, is often obtained by optimizing an objective function. This objective function can explicitly be included in the constraints of the main or upper minimization problem. This formulation results in a bi-level optimization or theoretical game problem. In this dissertation, the upper-level problem is formulated alternatively as linear and non-linear optimization problems. To solve the lower-level traffic assignment problem, a DTA simulation program, namely DYNASMART-P, is used to find the equilibrium flows. The suggested algorithm iterates between the upperlevel and the lower-level optimization problems for a pre-specified number of times or until convergence in terms of the estimated OD flows or the simulated link flows is achieved. To integrate the a priori information on OD demand flows with the information extracted from the link flow observations, adoption of the Bayesian inference method is proposed. If such information on OD flows is available, Bayesian inference treats the old information as the target values to update the estimated OD flows from the sample of the link flow observations.Civil, Architectural, and Environmental Engineerin

Collagen Partition in Polymeric Aqueous Two-Phase Systems for Tissue Engineering

Aqueous two-phase systems (ATPS) of polyethylene glycol (PEG) and dextran (DEX) are commonly used to partition proteins. Protein partition in ATPS is a complex phenomenon and depends on factors including molecular weight of polymers, and electrochemical and ionic properties of the phases. We studied the effect of polymer molecular weight on the partition of a natural protein, collagen, in several ATPS formulations made with non-ionic polymers polyethylene glycol (PEG) and dextran (DEX). We found that partitioning of collagen to an aqueous phase significantly increases when the molecular weight of the corresponding phase polymer decreases. Additionally, a large difference between the molecular weight of the phase-forming polymers was necessary to cause a significant uneven collagen distribution between the aqueous phases. We then employed one of the systems to create a three-dimensional breast cancer microtissue by entrapping a spheroid of breast cancer cells within the partitioned collagen. This convenient technique to generate 3D microtissues offers a convenient and promising approach for tissue engineering applications