Patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent

We present the special arterial fluid mechanics techniques we have developed for patient-specific computer modeling of blood flow in cerebral arteries with aneurysm and stent. These techniques are used in conjunction with the core computational technique, which is the space?Ctime version of the variational multiscale (VMS) method and is called ??DST/SST-VMST.?? The special techniques include using NURBS for the spatial representation of the surface over which the stent mesh is built, mesh generation techniques for both the finite- and zero-thickness representations of the stent, techniques for generating refined layers of mesh near the arterial and stent surfaces, and models for representing double stent. We compute the unsteady flow patterns in the aneurysm and investigate how those patterns are influenced by the presence of single and double stents. We also compare the flow patterns obtained with the finite- and zero-thickness representations of the stent.     

Finding meaning in a celebrity’s death: The relationship between parasocial attachment,grief, and sharing educational health information related to Robin Williams on social network sites

Celebrity health events can have a positive effect on public health education and awareness, in part because people spread health information related to the celebrity on social network sites. This may be particularly true in the event of celebrity deaths or other tragedies, when social network sites provide a convenient, public space to connect with others to mourn. However, little is understood about the circumstances that encourage health information sharing following these events. Using a Mechanical Turk sample (N = 281), this study employed a questionnaire to examine the role of parasocial attachment to Robin Williams and experienced grief following his suicide in explaining health information sharing on social network sites (i.e., sharing information about clinical depression, suicide prevention, substance abuse treatment, and Parkinson’s disease). Grief mediated the effect of parasocial attachment on health information sharing, but a moderated mediation analysis revealed that grief motivated health education on social network sites only for individuals who were coping by trying to find positive meaning in his death.     

Human behavior in a staircase during a total evacuation drill in a high‐rise building

Many studies have been conducted on the evacuation behavior on the staircases of buildings, but very little data are available for a situation with many occupants in a crowded high‐rise building. Therefore, this study investigated the evacuation behavior of a large number of evacuees on the staircase of a 25‐story high‐rise building. A total evacuation drill was conducted with 2088 evacuees, and the behavior of 1136 evacuees on the landings of the south staircase was recorded by a video recorder on the ceiling. The relationship between the density and speed of the evacuees on the landings was analyzed from the evacuation data for two situations: without and with merging in the stair flow. The evacuation stair flow in this drill had merging occupants entering from the floors, but no one entered from the lower floors during the latter period of the drill. Therefore, the flow during the latter period was treated as non‐merging flow, for which it was observed that, when the staircase was fully crowded, the density on the landings in the moving situation was different from that in the stopped situation. Moreover, the density on the landings was different from that on the treads. Furthermore, in the merging flow, a merging ratio of approximately 50:50 occurred during the congested evacuation. Copyright © 2016 John Wiley & Sons, Ltd.     

Space–time interface-tracking with topology change (ST-TC)

To address the computational challenges associated with contact between moving interfaces, such as those in cardiovascular fluid–structure interaction (FSI), parachute FSI, and flapping-wing aerodynamics, we introduce a space–time (ST) interface-tracking method that can deal with topology change (TC). In cardiovascular FSI, our primary target is heart valves. The method is a new version of the deforming-spatial-domain/stabilized space–time (DSD/SST) method, and we call it ST-TC. It includes a master–slave system that maintains the connectivity of the “parent” mesh when there is contact between the moving interfaces. It is an efficient, practical alternative to using unstructured ST meshes, but without giving up on the accurate representation of the interface or consistent representation of the interface motion. We explain the method with conceptual examples and present 2D test computations with models representative of the classes of problems we are targeting.     

Microstructural evolution of as-cast Th–U alloys

Microstructural evolution of as-cast (arc-melted) microstructures of selected compositions of Th–U alloys is investigated. Characterizations are done using XRD, optical microscopy, SEM, TEM and hardness measurement. Microstructures vary from single phase to biphasic with increase in uranium content in thorium. Uranium is present as spheroids (<1 μm) or islands (∼7 μm) in high thorium (<10.7 wt.% U) alloys. With further increase in uranium content it forms an interconnected network of uranium rich phase and gets interspersed with similar network of thorium rich phase. High uranium Th–U alloys has dendrites of thorium dispersed in uranium rich phase. Grain size refinement of thorium rich phase is effective up to ≤10.7 wt.% uranium addition. Hardness of Th–U alloys increases with increase in uranium content. Comparatively lower hardness observed in Th–96U is due to presence of softer eutectic colonies in the microstructures. High thorium alloys have potentials for being utilized as dispersion type fuel with fissile uranium spread in thorium matrix.     

Clustering household energy-saving behaviours by behavioural attribute

Research on household energy conservation often categorizes targeted behaviours by their behavioural attributes (e.g., savings, cost, frequency). The most common distinction in the literature divides behaviours as follows: (1) low-impact, low-cost, repetitive behaviours that result in a loss of comfort or curtailment behaviours and (2) high-impact, high-cost, infrequent behaviours that result in no loss of amenities or efficiency behaviours. However, such categorizations have often been ad hoc and two-dimensional (e.g., low-impact vs. high-impact, low-cost vs. high-cost). In contrast, we systematically assess a large range of household energy-saving behaviours (N=261) across nine attributes – energy savings, cost, frequency of performance, required skill level, observability, locus of decision, household function, home topography, and appliance topography. By clustering behaviours according to these attributes, we discern four clusters of energy-saving behaviours: family style, call an expert, household management and weekend project. We discuss the implications of these clusters for intervention design.     

Identification and characterisation of steel corrosion using passive high frequency RFID sensors

High frequency RFID sensors are attractive in diverse applications where sensor performance is required at a low cost and dimension restriction. An approach adapting commercial passive 13.56 MHz RFID tags has been developed for sensing corrosion stage. This investigation includes balance of sensing and positioning of RFID sensors for corrosion detection by analysing real and imaginary parts of the complex impedance. With passive HF RFID sensors, real part and imaginary part of complex impedance have been extracted from the reader coil with VNA (vector network analyser) and delivering a unique capability for corrosion sensing with different atmospheric exposure time steel samples (1 month, 6 months, 10 months and 12 months). With different positioning (5–25 mm), features extraction based on the complex impedance with PCA (principal component analysis) has been designed for position-independent corrosion evaluation.     

Focal calcium monitoring with targeted nanosensors at the cytosolic side of endoplasmic reticulum

Ca²⁺ distribution is spatially and temporally non-uniform inside cells due to cellular compartmentalization. However, Ca²⁺ sensing with small organic dyes, such as fura-2 and fluo-4, has been practically applied at a single cell level where the averaged signal from freely diffusing dye molecules is acquired. In this study, we aimed to target azide-functionalized fura-2 (N₃-fura-2) to a specific site of subcellular compartments to realize focal Ca²⁺ sensing. Using scAVD (single-chain avidin)–biotin interaction and a copper-free click reaction system, we linked N₃-fura-2 to specifically-targeted scAVD protein fused with a red fluorescent protein mCherry, so that Ca²⁺ sensors conjugated with four N₃-fura-2 dyes with dibenzocyclooctyne (DBCO)-PEG4-biotin as a linker were generated at subcellular compartments in living cells. In cytoplasm, N₃-fura-2 showed a prolonged retention period after binding to scAVD. Furthermore, the reacted N₃-fura-2 was retained inside cells even after free dyes were washed out by methanol fixation. When scAVD was overexpressed on endoplasmic reticulum (ER) membranes, N₃-fura-2 was accumulated on ER membranes. Upon histamine stimulation, which increases cytosolic Ca²⁺ concentration, ER-localized N₃-fura-2 successfully sensed the Ca²⁺ level changes at the cytosolic side of ER membrane. Our study demonstrated specific targeting of N₃-fura-2 to subcellular compartments and the ability of sensing focal Ca²⁺ level changes with the specifically targeted Ca²⁺ sensors.