The holmium laser, which operates in a wavelength of 2.1 microns, is highly absorbed by water and has a shallow penetration depth of approximately 0.4 mm. As a pulsed mode laser, the Holmium reduces deeper thermal effects and charring which are more prevalent in Continues Wave lasers (e.g. Thulium, KTP).
In statistical theory, covariance is a measure of how much two random variables change together. In other words, covariance is a measure of the strength of the correlation between two random variables. Also, it can be considered as a generalization of the concept of variance of two random variables.
In short, the covariance just tells you that two variables change the same way, while correlation reveals how a change in one variable effects a change in the other. The covariance can also be used to find the standard deviation of a multi-stock portfolio.The standard deviation is the accepted calculation for risk, and this is extremely important when selecting stocks.ses of Covariance. Finding that two stocks have a high or low covariance might not be a useful metric on its own. Covariance can tell how the stocks move together, but to determine the strength of the relationship, we need to look at the correlation.