Investigation of spiral blood flow in a model of arterial stenosis

The spiral component of blood flow has both beneficial and detrimental effects in human circulatory system [Stonebridge PA, Brophy CM. Spiral laminar flow in arteries? Lancet 1991; 338: 1360–1]. We investigate the effects of the spiral blood flow in a model of three-dimensional arterial stenosis with a 75% cross-sectional area reduction at the centre by means of computational fluid dynamics (CFD) techniques. The standard κ–ω model is employed for simulation of the blood flow for the Reynolds number of 500 and 1000. We find that for Re = 500 the spiral component of the blood flow increases both the total pressure and velocity of the blood, and some significant differences are found between the wall shear stresses of the spiral and non-spiral induced flow downstream of the stenosis. The turbulent kinetic energy is reduced by the spiral flow as it induces the rotational stabilities in the forward flow. For Re = 1000 the tangential component of the blood velocity is most influenced by the spiral speed, but the effect of the spiral flow on the centreline turbulent kinetic energy and shear stress is mild. The results of the effects of the spiral flow are discussed in the paper along with the relevant pathological issues

Large-Eddy simulation of pulsatile blood flow

Large-Eddy simulation (LES) is performed to study pulsatile blood flow through a 3D model of arterial stenosis. The model is chosen as a simple channel with a biological type stenosis formed on the top wall. A sinusoidal non-additive type pulsation is assumed at the inlet of the model to generate time dependent oscillating flow in the channel and the Reynolds number of 1200, based on the channel height and the bulk velocity, is chosen in the simulations. We investigate in detail the transition-to-turbulent phenomena of the non-additive pulsatile blood flow downstream of the stenosis. Results show that the high level of flow recirculation associated with complex patterns of transient blood flow have a significant contribution to the generation of the turbulent fluctuations found in the post-stenosis region. The importance of using LES in modelling pulsatile blood flow is also assessed in the paper through the prediction of its sub-grid scale contributions. In addition, some important results of the flow physics are achieved from the simulations, these are presented in the paper in terms of blood flow velocity, pressure distribution, vortices, shear stress, turbulent fluctuations and energy spectra, along with their importance to the relevant medical pathophysiology

The impact of a computerized decision aid on empowering pregnant women for choosing vaginal versus cesarean section delivery: study protocol for a randomized controlled trial

Cesarean delivery on maternal request (CDMR) is one of the main reasons for cesarean delivery in Iran, and women often need help in making a decision about the delivery options available to them. The main objective of this study is to evaluate the effect of a computerized decision aid (CDA) system on empowering pregnant women in choosing an appropriate mode of delivery. This CDA contrasts the advantages and disadvantages of vaginal versus cesarean section delivery in terms of their value to the individual woman. The protocol concerns a randomized trial study that will be performed among Iranian women. Four hundred pregnant women will be recruited from two private and two public prenatal centers in Mashhad, Iran. They will be randomly assigned to either an intervention or a control group. The designed CDA will be provided to the intervention group, whereas the control group will only receive routine care. The CDA provides educational contents as well as some recommendations. The CDA's knowledge base is obtained from the results of studies on predictors of cesarean delivery. The CDA's software will be installed on women's computers for use at home. The two primary outcomes for the study are O'Connor's Decisional Conflict Scale and knowledge as measured by true/false questions. Actual mode of delivery (vaginal versus cesarean) will be compared in the two groups. We investigate the effect of a CDA on empowering pregnant women in terms of reducing their decisional conflict as well as on improving their clinical knowledge pertaining to mode of delivery. This trial is registered with the Iran Trial Registrar under registration number IRCT2015093010777N4 and registration date 26 October 201

LingoBee and Detached Learners

LingoBee is a mobile application, which was designed as a tool for language learning. This application assists learners by providing them a community for language learning. This mobile app is running on Android operation system, and using Web 2.0 technology.There are pre-existing social network applications that is used for language learning such as Livemocha. But LingoBee focuses not only on social network sites but also creating communities for language learning.In this thesis I will analyze LingoBee user data collection, in order to evaluate this application. This evaluation is based on two aspects. First, LingoBee can provide an environment for learners to develop their learning process. Second, LingoBee gives the language learning communities the necessary environment to improve. There are too many articles exists on these topics but none of them have consider these to aspects together

The Role of Coherent Research-Based Curricular Unit in Mediating Students’ Integrated Vision of Human Impact on the Environment

[EN] The ongoing development of the high school ecology curricular unit presented in this proposal is a response to the new tide of educational reforms in the United States. This curricular unit represents an attempt to frame K-12 science curriculum around three dimensions: crosscutting concepts, disciplinary core ideas and scientific practices recently released in the report on a Framework for New K-12 Science Education (National Research Council, 2012). Integration of three dimensions into the development of agriculture-related curricular unit reflects complexity and logic inherent in science education facilitating deeper conceptual understanding. The development of this curricular unit takes place under the initiative of the National Science Foundation (NSF) funded project and explores the efficacy of the agriculture-related unit on students’ integrated vision of the human impact on natural systems. Research project seeks to recognize the characteristics that identify research-based curriculum (Clements, 2007). The interdisciplinary nature of this project has the potential to investigate how close adherence to features identifying research-based curriculum can support the development of coherent curricular unit mediating students’ integrated vision of environmental issues. Mediation results of this nature have larger implications on future efficacy studies of curriculum intervention.Ghalichi, N.; Roehrig, G. (2017). The Role of Coherent Research-Based Curricular Unit in Mediating Students’ Integrated Vision of Human Impact on the Environment. En Proceedings of the 3rd International Conference on Higher Education Advances. Editorial Universitat Politècnica de València. 965-973. https://doi.org/10.4995/HEAD17.2017.5489OCS96597

Turbulence modeling in three-dimensional stenosed arterial bifurcations

Under normal healthy conditions, blood flow in the carotid artery bifurcation is laminar. However, in the presence of a stenosis, the flow can become turbulent at the higher Reynolds numbers during systole. There is growing consensus that the transitional k ? model is the best suited Reynolds averaged turbulence model for such flows. Further confirmation of this opinion is presented here by a comparison with the RNG k? model for the flow through a straight, nonbifurcating tube. Unlike similar validation studies elsewhere, no assumptions are made about the inlet profile since the full length of the experimental tube is simulated. Additionally, variations in the inflow turbulence quantities are shown to have no noticeable affect on downstream turbulence intensity, turbulent viscosity, or velocity in the k? model, whereas the velocity profiles in the transitional k? model show some differences due to large variations in the downstream turbulence quantities. Following this validation study, the transitional k? model is applied in a three-dimensional parametrically defined computer model of the carotid artery bifurcation in which the sinus bulb is manipulated to produce mild, moderate, and severe stenosis. The parametric geometry definition facilitates a powerful means for investigating the effect of local shape variation while keeping the global shape fixed. While turbulence levels are generally low in all cases considered, the mild stenosis model produces higher levels of turbulent viscosity and this is linked to relatively high values of turbulent kinetic energy and low values of the specific dissipation rate. The severe stenosis model displays stronger recirculation in the flow field with higher values of vorticity, helicity, and negative wall shear stress. The mild and moderate stenosis configurations produce similar lower levels of vorticity and helicity. DOI: 10.1115/1.240118

Equitable access to quality injury care; Equi-Injury project protocol for prioritizing interventions in four low- or middle-income countries : a mixed method study

Funding This research was funded by the NIHR (award number 133135) using UK aid from the UK Government to support global health research. The views expressed in this publication are those of the authors and not necessarily those of the NIHR or the UK governmentPeer reviewe

Conceptualization of System Structure as a Stepping Stone to Systems Understanding among K-12 Students

University of Minnesota Ph.D. dissertation. May 2019. Major: Education, Curriculum and Instruction. Advisors: Gillian Roehrig, Anita Schuchardt. 1 computer file (PDF); x, 155 pages.A new vision set forth by the Framework for K-12 Science Education (National Research Council, 2012) highlights the importance of developing students’ abilities to think about systems as opposed to isolated facts. However, little evidence exists on how to foster students’ conceptualization of systems. It has been argued that conceptualization of systems structure serves as a stepping stone to understanding of systems (Arnold & Wade, 2015; Assaraf & Orion, 2005). Thus, this dissertation presents an analysis of students’ conceptualization of systems structure as a result of a curricular intervention at the high school level. The systems-oriented unit served as a context in which students’ identification of connections between components within a system could be investigated. Prior research exclusively examined conceptualization of processes to understand how students develop systems understanding (Kali, Orion & Eylon, 2003; Libarkin & Kurdziel, 200). Given the stipulated relationship between systems understanding and connections between material components that make up system structure, this study investigated students’ conceptualization of system structure through the ways in which they connect components within category of matter. The main objectives of the study were: 1) to examine the ways in which students identify connections between matter components within a system and use these connections as a basis for the development of a Systems Matter Framework (SMF), 2) to examine the validity of the developed framework by using this construct as a basis to evaluate students’ representations of connections between system components. The evaluation of SMF validity demonstrated that this framework can be used to track growing conceptualization of system structure and to relate it with the development of systems understanding. Therefore, the SMF can be used as an instrument for student evaluation. To examine generalizability, future research needs to examine SMF in different settings