Analysis of Blood Flow in Patient-specific Models of Type B Aortic Dissection

Aortic dissection is the most common acute catastrophic event affecting the aorta. The majority of patients presenting with an uncomplicated type B dissection are treated medically, but 25% of these patients develop subsequent dilatation and aortic aneurysm formation. The reasons behind the long‐term outcomes of type B aortic dissection are poorly understood. As haemodynamic factors have been involved in the development and progression of a variety of cardiovascular diseases, the flow phenomena and environment in patient‐specific models of type B aortic dissection have been studied in this thesis by applying computational fluid dynamics (CFD) to in vivo data. The present study aims to gain more detailed knowledge of the links between morphology, flow characteristics and clinical outcomes in type B dissection patients. The thesis includes two parts of patient‐specific study: a multiple case cross‐sectional study and a single case longitudinal study. The multiple cases study involved a group of ten patients with classic type B aortic dissection with a focus on examining the flow characteristics as well as the role of morphological factors in determining the flow patterns and haemodynamic parameters. The single case study was based on a series of follow‐up scans of a patient who has a stable dissection, with an aim to identify the specified haemodynamic factors that are associated with the progression of aortic dissection. Both studies were carried out based on computed tomography images acquired from the patients. 4D Phase‐contrast magnetic resonance imaging was performed on a typical type B aortic dissection patient to provide detailed flow data for validation purpose. This was achieved by qualitative and quantitative comparisons of velocity‐encoded images with simulation results of the CFD model. The analysis of simulation results, including velocity, wall shear stress and turbulence intensity profiles, demonstrates certain correlations between the morphological features and haemodynamic factors, and also their effects on long‐term outcomes of type B aortic dissections. The simulation results were in good agreement with in vivo MR flow data in the patient‐specific validation case, giving credence to the application of the computational model to the study of flow conditions in aortic dissection. This study made an important contribution by identifying the role of certain morphological and haemodynamic factors in the development of type B aortic dissection, which may help provide a better guideline to assist surgeons in choosing optimal treatment protocol for individual patient

A Study on the Narrative Style of Environmental Space in the Films Directed by Jia Zhangke From the Perspective of Still Life

The film is a kind of art characterized by combination of time and space. In the film, environment refers to the space with certain functions and it contains certain prescription and specific timeliness. Environments in the film include the natural environment and social environment and have various kinds of functions, in which narrativity is one of the important functions. Environment in the film not only is the background of the film story, but also can promote the development of the plot and deepen the theme in some films indeed. As the representative figure of the sixth-generation directors in China, Jia Zhangke’s unique visual language expression and film space narrative application have become the unique style and achievement in the film directing field of the world. Mountains May Depart, released in 2015, caused widespread concern in the world and gained high praise continuously after releasing. Meanwhile, creation of visual effect and application of space environment in Mountains May Depart completely adopted those in his another representative film Still Life. Environments in Still Life are of great significance due to their particularity and fully reflect the narrative function of the film environment.In Still Life, narrative functions of the film environments are mainly reflected in these three aspects, namely, the environment is regarded as the structure principle of the film narrative; the environment is the basis for shaping personal character and emotion; and in some plot and shot of the film, the environment is used for foiling the key person so as to emphasize the narrative function of the environmental scenery. In the film, the environment plays a role in the narrative of the film by means of above three aspects, and thereby achieving to promote the development of the plot and deepen the theme of the film eventually. The film is not only an art combining space and time, but also an art combining sound and pictures. When we study the narrative functions of the environments in the film from the perspective of audio-visual language of the film, we will find the skills of environment narrative functions in the film. Example by Still Life, both unique application of the long take and the scenery shot and adding to various ambient sounds enhance the narrative function of the environment in the Still Life. In this paper, the author will study the unique space environment narrative style of Jia Zhangke through above aspects related to Still Life.

Catalytic Conversion of Carbon-Containing Compounds into Valuable Chemicals and Fuels

Conversion of carbon-containing compounds, especially C1 compounds such as carbon dioxide and methane, to valuable chemicals and fuels will hopefully address concerns over decreasing supplies of fossil fuels and mitigate the eects of greenhouse gas emissions on global climate change. Many challenges, however, remain to be addressed before these technologies may be adopted on an industrial scale. Chiefly, catalysts must be developed to activate carbon-containing compounds from their thermodynamically stable ground states, using hydrogen, electrons, or heat as energy sources. We chose as model catalytic systems: 1) Metathesis of ethene and 2-butene; 2) Methane dehydrogenation and carbon dioxide hydrogenation. We developed three computational methodologies to study these processes across a range of length and time scales. First, we investigated how electronic structure affects the properties and reactivity of these catalyst systems; by computing the partial electronic density of states, electronic localization function, and excess spin density, we showed how redox supports, such as ceria, promote electron transfer reactions. We applied this to the studies of methane activation and carbon dioxide activation. Second, we developed a non-equilibrium thermodynamics approach to calculate energies of activation at nite temperatures, based on the Bronsted-Evans-Polanyi principle and the Nudged Elastic Band method. Third, we developed an approach to numerically compute heat capacities and other thermodynamic properties on extended catalytic systems that are comparable in accuracy and precision to methods that have been well-developed for gas-phase molecules. We applied these to the studies of metathesis propagation and carbon dioxide hydrogenation. We gained mechanistic, thermodynamic, and kinetic insight into the elementary steps that comprise larger reaction networks of interest to the broader catalysis community. Ultimately, these theoretical and computational predictions can be used to guide experimental design, synthesis, and characterization of new catalyst systems

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Observation of recoil-induced resonances and electromagnetically induced absorption of cold atoms in diffuse light

In this paper we report an experiment on the observation of the recoil-induced resonances (RIR) and electromagnetically induced absorption (EIA) of cold Rb87 atoms in diffuse light. The pump light of the RIR and the EIA comes from the diffuse light in an integrating sphere, which also serves the cooling light. The probe light beam is a weak laser split from the cooling laser in order to keep the cooling and probe lasers correlated. We measured the RIR and the EIA signal varying with the detuning of the diffuse laser light, and also measured the temperature of the cold atoms at the different detunings. The mechanism of RIR and EIA in the configuration with diffuse-light pumping and laser probing is discussed, and the difference of nonlinear spectra of cold atoms between in diffuse-light cooling system and in optical molasses as well as in a magneto-optical trap (MOT) are studied.Comment: 9 pages, 6 figure