What is the relation between right atrial pressure and cardiac output ?
Q. What is the relation between right atrial pressure and cardiac output ? does the cardiac output increase ? decrease ? or what ? I saw many figures in Guyton's showing that it is a direct relation (increase) but I am not convinced because I know that when right atrial pressure increases , the venous return decreases and thus the cardiac output will decrease ? Any explanation ?
Asked by lemaza - Tue Apr 13 04:04:21 2010 - - 1 Answers - 0 Comments

A. According to the concept of Guyton, cardiac output is largely controlled by venous return, which is determined by the difference between mean systemic venous pressure and right atrial pressure. In the analysis of the venous return curve, other authors have suggested that right atrial pressure is the dependent variable and venous return is the independent variable (right atrial pressure decreased because cardiac output increased). The present report analyzes this historical debate, which has already lasted > 50 years. One of the definitions of physiology is that it is the science of how the body works. The key to obtaining a full understanding of the human circulatory function is the determination of its autoregulation. In the steady… [cont.]
Answered by Alison S - Tue Apr 13 04:12:14 2010

How do you calculate work output and input?
Q. The raised end of a board is 1 meter above the ground. A 300-newton crate is pushed up the board a distance of 5 meters with an 80-newton force. What is the work input? Work output?
Asked by jonathan k - Mon Dec 17 22:37:29 2007 - - 1 Answers - 0 Comments

A. The work input is the 80N force multiplied by the distance 5m. which the force moves. That is 400 J. As long as the crate remains in positon, there is no work output. The work input has gone into giving the crate potential energy by virtue of its increased height above the starting point. If the crate is released and comes back down the slope, or falls off the end of the board, there will be an equal amount of work output giving it kinetic energy as it loses the potential energy.
Answered by Rackbrane - Tue Dec 18 06:24:41 2007

How do you calculate the annual output from a photovoltaic array?
Q. As an example: If you had 30m2 of photovoltaic panels, mounted at 0 degrees inclination in London, UK, what would the annual output be in kWh? Specs for the PVs: 1 kWp, 8m2 per kWp.
Asked by pottolom - Fri Aug 24 08:18:43 2007 - - 1 Answers - 0 Comments

A. You will never be able to calculate this precisely There are too many variables. For instance: The efficiency of the panels, their rated output, whatever degree of fogginess hading there might be, the amount of shading, how often the panels are cleaned, the efficiency of the inverters, and whether you have batteries. Perhaps you can find insolation (this is spelled correctly) tables on the Internet. Knock off 15 or 20 percent of that figure, and you will be as close as you can guess it. Also look on the Internet and in the search box near the top of this page to learn more to help you make solar decisions.
Answered by Ed - Fri Aug 24 11:28:29 2007