3-Dimensional Blood Clot Simulation On Plastic Arterial Catheter using GAMBIT & FLUENT

The Volume Of Fluid (VOF) model is a surface-tracking technique applied to a fixed Eulerian mesh. It is designed for two or more immiscible fluids where the position of the interface between the fluids is of interest. The fluids share a single set of momentum equations, and the volume fraction of each of the fluids in each computational cell is tracked throughout the domain. As such, VOF is an advection scheme that acts as a numerical recipe that allows the programmer to track the shape and position of the interface, but it is not a standalone flow-solving algorithm. The Navier Stokes equations describing the motion of the flow have to be solved separately. The movement of one fluid with regards to its interface is studied to help the researchers and engineers in deciding certain parameters such as pressure and velocity in plastic arterial catheter in order to reduce error, computational cost, and save simulation time. Good resemblance between CFD predictions with the experimental data in certain locations was obtained with the factor of species (blood clot) transport and pressure profile, where dependence of VOF models and grid sizes were discussed in details. The results show us that, the demand in grid study is vital to obtain accurate results with minimal computational cost. On the other hand, wall adhesion is solved in an iterative way, modifying holdups at the wall until the specified wall contact angle had been satisfied. Since the VOF method is a Direct Numerical Simulation (DNS) approach, the time and length scales on which the equations are being solved should be sufficiently small to directly take fluctuating fluid motion due to turbulence into account. Therefore, VOF simulations do not incorporate any other turbulence models, thus only applicable to laminar models

Do retinal ganglion cells project natural scenes to their principal subspace and whiten them?

Several theories of early sensory processing suggest that it whitens sensory stimuli. Here, we test three key predictions of the whitening theory using recordings from 152 ganglion cells in salamander retina responding to natural movies. We confirm the previous finding that firing rates of ganglion cells are less correlated compared to natural scenes, although significant correlations remain. We show that while the power spectrum of ganglion cells decays less steeply than that of natural scenes, it is not completely flattened. Finally, we find evidence that only the top principal components of the visual stimulus are transmitted.Comment: 2016 Asilomar Conference on Signals, Systems and Computer

Essays in exchange rate economics

This research analyses the key issues in exchange rate economics. It provides a systematic treatment of exchange rate volatility and its manifestations, the presence of nonlinearity in exchange rates, and the interaction between national price levels and exchange rates. The approach is empirical. The results of this study are expected to contribute to an understanding of the existing empirical puzzles that profoundly impact economic policy-making and business

Renovation or Redevelopment: The Case of Smart Decision-Support in Aging Buildings

In Germany, as in many developed countries, over 60% of buildings were constructed before 1978, where most are in critical condition, requiring either demolition with plans for redevelopment or renovation and rehabilitation. Given the urgency of climate action and relevant sustainable development goals set by the United Nations, more attention must be shifted toward the various sustainability aspects when deciding on a strategy for the renovation or redevelopment of existing buildings. To this end, this study focused on developing a smart decision support framework for aging buildings based on lifecycle sustainability considerations. The framework integrated digital technological advancements, such as building information modeling (BIM), point clouds processing with field information modeling (FIM)®, and structural optimization, together with lifecycle assessment to evaluate and rate the environmental impact of different solutions. Three sustainability aspects, namely, cost, energy consumption, and carbon emissions, were quantitatively evaluated and compared in two scenarios, namely, renovation, and demolition or deconstruction combined with redevelopment. A real building constructed in 1961 was the subject of the experiments to validate the framework. The result outlined the limitations and advantages of each method in terms of economics and sustainability. It was further observed that optimizing the building design with the goal of reducing embodied energy and carbon in compliance with modern energy standards was crucial to improving overall energy performance. This work demonstrated that the BIM-based framework developed to assess the environmental impact of rehabilitation work in aging buildings can provide effective ratings to guide decision-making in real-world projects

Polyamines Regulate Chilling Response in Ripening Tomato Fruits by De Novo Transcription

Plants response to various abiotic stress, including chilling injury, by differentially regulating genes responsible for protection against these stresses. Polyamines (PAs); putrescine (Put), spermidine (Spd), and spermine (Spm), are ubiquitous metabolite in all organisms and have been implicated in abiotic stresses in plants. Dr. Handa laboratory has previously developed high Spd/Spm tomato fruits genotypes by expressing yeast S-adenosylmethionine decarboxylase (SAMDC). In present investigation, the role of Spd/Spm in chilling injury was evaluated by using two independent transgenic lines with high Spd/Spm (556 and 579) and isogenic parental Ohio 8245 (WT) genotypes. Fruits at onset of ripening (Breaker, BR) and fully ripe (Breaker+8 days, BR+8) from both transgenic lines and WT were subjected to chilling by storing at 5°C or 8ºC. Results showed that the 556 and 579 fruits exhibit more chilling tolerance phenotype at BR+8 stage but performed poorly at BR stage compared to WT fruit. RNA-seq analyses of transcriptome showed differential expression of a large number of genes in response to chilling treatment of high Spd/Spm fruit compared to WT fruit, which suggesting a significant effect of PAs in chilling response mechanism. PAs are implicated in regulating genes related to redox homeostasis (Thioredoxin family protein), stress signaling pathway (MAPK cascade), various cold responsive genes, protein chaperon (heat shock proteins) and cellular antioxidant system (CAT, SOD and APX). It can be postulated that, being positive charged molecules, PAs bind to DNA, RNA and transcription factors and differentially regulate expression of genes associated with chilling tolerance in ripened fruits that help acclimate fruits to sub optimal chilling temperature

Does national investment on R&D compared to military expenditure achieve greater development?

Research investment and military expenditure are generally of opposite character. Military spending is higher than research and development (R&D) because of global insecurity and power politics. We show the merit of research and development (R&D) investment and how it contributes to the national human capital. We further assess the impact of the expenditure gap between these two on the Human Development Index (HDI) and Gross Domestic Product (GDP). Data from 76 countries for a period of 15 years (2000-2014) were analysed by mixed effect models adjusting the effect of the six different continents. There exists a positive bi-directional significant relationship between the HDI and R&D investment. R&D tend to contribute to human capital, which in turn contributes to the public development over the years, whereas the military expenditure that only marginally contributes towards GDP, not HDI

Studying the wake of an island in a macro-tidal estuary

Tidal flow can generate unsteady wakes, large eddies and recirculation zones in the lee or around complex natural and artificial obstructions, such as islands, headlands or harbours. It is essential to understand the flow patterns around such structures given the potential impacts they can have on sedimentation, the marine environment, ecology and anthropogenic activities. In this paper, the wake around an island in a macro-tidal environment has been studied using a widely used hydro-environmental model, Telemac-2D. Current data collected using moored acoustic Doppler current profilers (ADCPs) were used to validate and refine the Telemac-2D model. Four different turbulence models and several different solver options for the k-ε model were tested in this study to assess which representation could best replicate the hydrodynamics. The classic k-ε model with the solver of conjugate residual was the most suitable method to simulate the wake in the lee of the island. The model results showed good correlation with measured data. The island wake parameter used to predict the wake behaviour and its predictions matched the model results for different tidal conditions, suggesting that the island wake parameter could be used to predict the wake behind obstacles in macro-tidal environments. The model predictions showed the development of a wake is similar between ebb and flood tides in the neap tide while showing more difference in spring tide. With the increase of velocity in the neap tide, two side-by-side vortices will appear and then changing to stable Karman Vortex Street. During the edd phase, the wake will develop from a stable vortex to an unstable Karman Vortex Street, while the wake remained stable with two vortices during an flood ti