Finite element analysis of embedded blood vessel mechanics

Cardiac pump function is closely linked to myocardial oxygen supply during the cardiac cycle. Variations in cardiac output must be met with concurrent shifts in tissue blood flow if changing myocardial oxygen requirements are to be satisfied. Of particular importance is the adequate perfusion of the left ventricular myocardium. Experimental evidence indicates that some ninety percent of left ventricular oxygen demand is generated during systolic contraction of the myocardium. Paradoxically, blood flow measurements in the left coronary artery suggest minimal systolic perfusion. The asynchronous, phasic character of left coronary blood flow and myocardial oxygen demand has prompted much research into the time dependent origins of coronary flow impedance. Various (sometimees conflicting) theories have been proposed, all of which suggest tissue blood delivery is significantly influenced by mechanical interactions between the myocardium and its embedded vascular network. Such interactions become particularly acute during systole, where myocardial contraction produces deformations and stress contractions which influence embedded vessel patency, coronary flow impedance, and effective driving pressure

Estimates of genetic parameters from a selection experiment for growth and reproductive success in Tribolium castaneum by using different statistical methods

The general problem of estimating breeding values of animals in a population under selection to improve performance for growth and reproductive success is addressed. Genetic and environmental (co)variances for correlated traits must be estimated from the data if they are unknown or expected to have changed due to the type of selection. The data were a set of four lines, one selected for increased pupa weight, another for increased family size, the third based on an index combining pupa weight and family size, and a randombred control. The analysis of genetic responses over 16 generations in these four selection lines derived from a common base population present some interesting phenomena likely to be encountered in the analysis of other populations under selection. Changes in genetic and environmental (co)variances associated with selection for pupa weight were found to have a profound effect on estimates of (co)variance components within and between generations. New insight is provided on ways to interpret restricted maximum likelihood estimates of genetic parameters. Base populations and control lines with 16 generations of data from two replicated experiments were used to show how insufficient data, misidentification of major fixed effect when combining data across experiments, and confounding of random effects can lead to widely different estimates of parameters for the same data. Gibbs sampling techniques were used to implement a full Bayesian analysis of the data. All (co)variance components in the model were not estimated with equal information from the data. Extensive use was made of the 95% central interval of the posterior distribution to graphically show the effect of different assumptions about prior knowledge or belief in the realized values of random variables. Even a small amount of weight on prior knowledge about parameters can overcome problems associated with the belief that all information must come entirely from the data. A multiple trait heterogeneous mixed model is proposed to adjust for the effects of genotype by environment interaction. It is argued that this model overcomes several deficiencies of other models proposed to account for heterogeneous (co)variances

A Comparison of Music as a Therapy Before and After the 20th Century in America

This piece provides a historical overview of the use of music as a therapy in the Unites States, with an emphasis on the changes that have occurred over the past century

A Study of Cotton Breeding

No abstract presen

Parametric analysis of a novel semi-circular microfluidic CD-ELISA valve

CD-ELISA uses the microfluidic ranking method and centrifugal force to control the testing solution as it flows into the reaction region. The most challenging part of CD-ELISA is controlling the flow process for different biological testing solutions, i.e. the controlling sequence for the microfluidic channel valves. The microfluidic channel valve is therefore the most important fluid channel structure for CD-ELISA. In this study, we propose a valve design suitable for a wide range rotational speeds which can be applied for mass production (molding). Together with supporting experiments, simulation based on two-phase flow theory is used in this study, and the feasibility of this novel valve design is confirmed. Influencing design factors for the microfluidic channel valves in CD-ELISA are investigated, including various shapes of the arc, distance d, radius r, the location of the center of the circle, and the contact angle. From both the experimental results and the simulated results, it is evident that the narrowest channel width and the contact angle are the primary factors influencing valve burst frequency. These can be used as the main controlling factors during the design