I dont know yet Assignment Example | Topics and Well Written Essays - 2000 words

I dont know yet - Assignment Example For the purpose of making a similar investigation, this study used data involving 500 cases. Data are available on market-to-book-value (MBV), identity of the largest owner, â€Å"concentration of ownership† assessed in terms of the percentage share of the largest owner, size in terms of the total assets of the company, return on capital in percent (ROCE), and industry type. Therefore, there were six variables. However, because this investigation is limited to the relationship between ownership structure and company performance, there were only four relevant variables: MBV, identity, concentration of ownership, and ROCE. The relevant independent variables for the study are â€Å"identity of the largest owner† and the â€Å"concentration of ownership† assessed in terms of the percentage share of the largest owners. In contrast, the relevant dependent variables or company performance variables appropriate from the data set are MBV and ROCE. There was no need to use the variable â€Å"industry† because it is irrelevant for the focus of our study. Of course, our study can also cover whether the effect of the independent variables differ in each type of industry or whether the specific effect of the independent variables vary depending in manufacturing, services, and primary industries. However, we need not do this. Similarly, we do not have to cover firm size based on asse ts because firms can be small or large but asset size does not imply performance. Of course, we can also construct empirical investigations that differentiate the effects based on asset size but, again, we do not have to do this. We focus in this section on variables that may indicate a possible presence or absence between firm ownership structure and firm performance. In Figure 1, we investigate the scattergram pattern if we have the percentage share of the largest owner of a firm and market to

Factors affecting quality of MRI image.Benefits of circular or square Essay

Factors affecting quality of MRI image.Benefits of circular or square spiral EPI methods - Essay Example For example, if a spin is exposed to a magnetic field different from the expected value due to magnetic susceptibility, geometric distortions will be seen from the MRI image (Reinsberg, Doran, Charles-Edwards, and Leach, 2005). In particular, an increased spin produces MRI signals of low intensity, while high magnetic susceptibility areas are seen as areas of total signal loss (Zhou and Gullapalli, 2006). Figure 1 shows an example of metallic susceptibility distortions in the presence of metallic implants. Magnetic susceptibility In magnetic resonance imaging, tissues are temporarily magnetized by the large magnetic field that the imaged subject is exposed to, with the extent of magnetization varying among tissues that differ in magnetic susceptibility. For example, relative to other tissues, air and bone are less susceptible to magnetization. On the other hand, metallic implants have high magnetic susceptibility as compared to the body tissues. These differences in magnetic suscepti bility cause field inhomogeneity, especially in tissue boundaries, particularly air-tissue and bone-soft tissue boundaries (Zhou and Gullapalli, 2006). That is why magnetic susceptibility distortions are sometimes seen in such boundaries, like the sinuses (Reinsberg, Doran, Charles-Edwards, and Leach, 2005). 1. Discuss various methods to correct for magnetic susceptibility distortions, while maintaining a good EPI image. ... a.) Parameters that can optimize EPI image ESP can be decreased through the use of powerful gradients, such as increased gradient slew rate (~20, 000 T/m/s), increased maximum amplitude (350 mT/m), increased rise time rate, increased accuracy, decreased eddy currents, increased voltage, and decreased field strength. In addition, these parameters decrease signal-to-noise ratio. Meanwhile, a decreased ESP results to a smaller total train length time. In fact, it has been estimated that decreasing ESP to 40 ms limits the distortion to only one pixel wide. Similarly, increased data gathering via decreased frequency- and phase encoding steps and ramp sampling, fast analogue to digital converters and large receiver bandwidth decrease the time in which phase errors can accumulate (McMahon, 2012). On the other hand, phase and read directions can be swapped, so that the phase encoding gradient is along the same axis as susceptibility gradients. Although this may not totally prevent distortion , it shows the image in a more presentable and understandable manner (McMahon, 2012; Zhou and Gullapalli, 2006). Figure 2 shows the decrease in magnetic susceptibility upon converting from left-right phase encoding to anterior-posterior phase encoding. Other ways to minimize magnetic susceptibility distortions include decreasing the resolution, use of SE sequence, increased acquisition matrix and proper shimming before image acquisition. It should be noted, however, that heating of nearby tissues can occur when using fast SE acquisition with a high bandwidth to decrease magnetic susceptibility distortions resulting from metallic implants (Zhou and Gullapalli, 2006). b) Chain of consequences after increasing the receiver bandwidth Receiver bandwidth is a