Numerical solutions of 3-dimensional Navier-Stokes equations for closed bluff-bodies

The Navier-Stokes equations are solved numerically. These equations are unsteady, compressible, viscous, and three-dimensional without neglecting any terms. The time dependency of the governing equations allows the solution to progress naturally for an arbitrary initial guess to an asymptotic steady state, if one exists. The equations are transformed from physical coordinates to the computational coordinates, allowing the solution of the governing equations in a rectangular parallelepiped domain. The equations are solved by the MacCormack time-split technique which is vectorized and programmed to run on the CDc VPS 32 computer. The codes are written in 32-bit (half word) FORTRAN, which provides an approximate factor of two decreasing in computational time and doubles the memory size compared to the 54-bit word size

Application of the method of lines for solutions of the Navier-Stokes equations using a nonuniform grid distribution

The feasibility of the method of lines for solutions of physical problems requiring nonuniform grid distributions is investigated. To attain this, it is also necessary to investigate the stiffness characteristics of the pertinent equations. For specific applications, the governing equations considered are those for viscous, incompressible, two dimensional and axisymmetric flows. These equations are transformed from the physical domain having a variable mesh to a computational domain with a uniform mesh. The two governing partial differential equations are the vorticity and stream function equations. The method of lines is used to solve the vorticity equation and the successive over relaxation technique is used to solve the stream function equation. The method is applied to three laminar flow problems: the flow in ducts, curved-wall diffusers, and a driven cavity. Results obtained for different flow conditions are in good agreement with available analytical and numerical solutions. The viability and validity of the method of lines are demonstrated by its application to Navier-Stokes equations in the physical domain having a variable mesh

Extension of multigrid methodology to supersonic/hypersonic 3-D viscous flows

A multigrid acceleration technique developed for solving 3-D Navier-Stokes equations for subsonic/transonic flows was extended to supersonic/hypersonic flows. An explicit multistage Runge-Kutta type of time stepping scheme is used as the basic algorithm in conjunction with the multigrid scheme. Solutions were obtained for a blunt conical frustum at Mach 6 to demonstrate the applicability of the multigrid scheme to high speed flows. Computations were performed for a generic High Speed Civil Transport configuration designed to cruise at Mach 3. These solutions show both the efficiency and accuracy of the present scheme for computing high speed viscous flows over configurations of practical interest

Human Umbilical Cord Blood Stem Cells Differentiate into Keratinocytes under In Vitro Conditions and Culturing Differentiated Cells on Bacterial Cellulose Film

Mesenchymal stem cells (MSC) are capable of self renewing and differentiating into other cell types. Human umbilical cord blood (HUCB) has been investigated as an alternative source to bone marrow. The aim of our examinations was to investigate MSC of HUCB could differentiate into keratinocytes under in vitro conditions. In this study, we examined the differentiation with chemical compounds, then to identify the stem cells are differentiated or not, PCR by using the expression of gene cytokeratin 18 was performed and to examine the proliferation characteristic of differentiated keratinocyte from HUCBMSCs, cultured them on cellulose film. Analysis of PCR confirmed the expression of cytokeratin 18 in keratinocytes; results of our study show that cellulose film isn’t a compatible substrate for differentiated keratinocytes. And growth factor, BMP4, with hydrocortisone and ascorbic acid with specific amounts is an appropriate induction factor for inducing of differentiation into keratinocytes

Micro-focussed XAFS spectroscopy to study Ni-bearing precipitates in the metal of corroded Zircaloy-2

The present work concerns an investigation of the local atomic environment of Ni-containing secondary phase precipitates (SPP) present in the metal-part of Zircaloy-2 cladding tubes. An unirradiated Zircaloy-2 and two specimens irradiated in a commercial nuclear power plant are characterized using μ-focussed synchrotron radiation, and by x-ray absorption fine structure (XAFS) spectroscopy. The patterns of Ni K-edge XANES and EXAFS of SPP in unirradiated and irradiated cladding are found different. Considering the fact that Ni-bearing SPP in the unirradiated samples are mainly Zintl phase Zr2(Fe, Ni) type, a detailed EXAFS analysis of near-neighbor Ni atoms has been made. The result of a curve fit for the first two shells shows that about 2 Ni(Fe) and 8Zr atoms are coordinated at2.68 and 2.77Å, respectively, around a central Ni atom in the SPP. XANES data analysis provides total electronic density of states at the Fermi level of unirradiated Zr2(Fe, Ni). At the Ni K-edge EXAFS spectra of irradiated SPP, however, only a single scattering peak is observed demonstrating the structural disorder introduced by the neutron irradiation. The coordination number of the Ni neighboring shells is reduced markedly due to the formation of point and extended defects in the damaged SPP lattice. Dissolution of Ni from the SPP is also evident from the data. The results of this study provide a further basis for the description of both crystallographic and electronic structures of intermetallic second-phase precipitates found in Zr-based alloy

Precision grid and hand motion for accurate needle insertion in brachytherapy

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/98741/1/MPH004749.pd

Stakeholders' perspective on health equity and its indicators in Iran: A qualitative study

Background: To reduce the health inequity, it is necessary to measure and monitor these inequalities. In this regard, in Iran a plan was developed and accordingly 52 indicators to measure equity in health were developed and announced by the Ministry of Health in collaboration with other sectors. This study aims to obtain a deeper understanding of the development of health equity indicators and identify their implementation challenges and proposed solutions from the perspective of policy makers and executives responsible for the indicators development and implementation. Methods: In this qualitative study, data were gathered using semi-structured interviews with 15 Stakeholders involved in the development and implementation of these health equity indicators (at national and provincial levels), and the review and analysis of relevant documents including meeting minutes, working plans and working progress reports. Data were analyzed using a framework analysis approach. Results: Four main themes were identified, including the concept of equity in health and its importance, the use of health equity indicators and process of indicators development, challenges of development and implementation of the indicators and laying the groundwork for the establishment of indicators. The findings showed that policy makers' viewpoint on concepts and indicators is different from those of executives and their perceptions have little in common. The establishment of indicators requires accurate stakeholders' understanding and accurate insight into the issue of equity in health, political will, financing, training and empowerment of organization's employees, legal requirements, and finally a clear action plan. Conclusion: The development of the indicators requires a shared understanding among policy makers and executives. As the attention has been focused recently on the issue, in addition to knowledge improvement, proper solutions with an intersect oral collaboration approach in order to tackle challenges should be considered

Determinants of change in polypharmacy status in Switzerland: the population-based CoLaus study.

This study aimed to assess the prevalence, the change, and the determinants of change in polypharmacy in a population-based sample. Baseline (2003-2006) and follow-up (2009-2012) data are from 4679 participants aged between 35 and 75 years (53.5% women, mean age 52.6 ± 10.6 years) from the population of Lausanne, Switzerland. Polypharmacy was defined by the regular use of ≥5 drugs. Four categories of change were defined: never (no polypharmacy at baseline and follow-up), initiating (no polypharmacy at baseline but at follow-up), maintaining, or quitting. Polypharmacy increased from 7.7% at baseline to 15.3% at follow-up. Cardiovascular drugs were the most prescribed medicines at baseline and follow-up. Gender, age, obesity, smoking, previously diagnosed hypertension, or diabetes or dyslipidemia were significantly and independently associated with initiating and maintaining polypharmacy. In a population-based sample, prevalence of polypharmacy doubled over a 5.6-year period. The main determinants of initiating polypharmacy were age, overweight and obesity, smoking status, and previously diagnosed cardiovascular risk factors

Polypill eligibility and equivalent intake in a Swiss population-based study.

The polypill has been advocated for cardiovascular disease (CVD) management. The fraction of the population who could benefit from the polypill in Switzerland is unknown. Assess (1) the prevalence of subjects (a) eligible for the polypill and (b) already taking a polypill equivalent; and (2) the determinants of polypill intake in the first (2009-2012) and second follow-ups (2014-2017) of a population-based prospective study conducted in Lausanne, Switzerland. The first and the second follow-ups included 5038 and 4596 participants aged 40-80 years, respectively. Polypill eligibility was defined as having a high CVD risk as assessed by an absolute CVD risk ≥ 5% with the SCORE equation for Switzerland and/or presenting with CVD. Four polypill equivalents were defined: statin + any antihypertensive with (A) or without (B) aspirin; statin + calcium channel blocker (CCB) (C); and statin + CCB + angiotensin-converting enzyme inhibitor (D). The prevalence of polypill eligibility was 20.6% (95% CI 19.5-21.8) and 27.7% (26.5-29.1) in the first and second follow-up, respectively. However, only around one-third of the eligible 29.5% (95% CI 26.7-32.3) and 30.4% (27.9-33.0) respectively, already took the polypill equivalents. All polypill equivalents were more prevalent among men, elderly and in presence of CVD. After multivariable adjustment, in both periods, male gender was associated with taking polypill equivalent A (OR: 1.93; 95% CI 1.45-2.55 and OR: 1.67; 95% CI 1.27-2.19, respectively) and polypill equivalent B (OR: 1.52; 95% CI 1.17-1.96 and OR: 1.41; 95% CI 1.07-1.85, respectively). Similarly, in both periods, age over 70 years, compared to middle-age, was associated with taking polypill equivalent A (OR: 11.71; CI 6.74-20.33 and OR: 9.56; CI 4.13-22.13, respectively) and equivalent B (OR: 13.22; CI 7.27-24.07 and OR: 20.63; CI 6.51-56.36, respectively). Former or current smoking was also associated with a higher likelihood of taking polypill equivalent A in both periods. A large fraction of the population is eligible for the polypill, but only one-third of them actually benefits from an equivalent, and this proportion did not change over time

Coined quantum walks on percolation graphs

Quantum walks, both discrete (coined) and continuous time, form the basis of several quantum algorithms and have been used to model processes such as transport in spin chains and quantum chemistry. The enhanced spreading and mixing properties of quantum walks compared with their classical counterparts have been well-studied on regular structures and also shown to be sensitive to defects and imperfections in the lattice. As a simple example of a disordered system, we consider percolation lattices, in which edges or sites are randomly missing, interrupting the progress of the quantum walk. We use numerical simulation to study the properties of coined quantum walks on these percolation lattices in one and two dimensions. In one dimension (the line) we introduce a simple notion of quantum tunneling and determine how this affects the properties of the quantum walk as it spreads. On two-dimensional percolation lattices, we show how the spreading rate varies from linear in the number of steps down to zero, as the percolation probability decreases to the critical point. This provides an example of fractional scaling in quantum walk dynamics.Comment: 25 pages, 14 figures; v2 expanded and improved presentation after referee comments, added extra figur