Assessment of renal perfusion with 82-rubidium PET in patients with normal and abnormal renal function.

Background: Noninvasive measurement of renal blood flow (RBF) and renal vascular resistance (RVR) is challenging, yet critical in renal pathologies. This study evaluates the correlation between serum renal function markers and RBF/RVR assessed using rubidium PET.

Methods: Dynamic images from 53 patients who underwent rubidium PET for nonrenal indications were analyzed.

Probability and consequences of living inside a computer simulation.

It is shown that under reasonable assumptions a Drake-style equation can be obtained for the probability that our universe is the result of a deliberate simulation. Evaluating loose bounds for certain terms in the equation shows that the probability is unlikely to be as high as previously reported in the literature, especially in a scenario where the simulations are recursive. Furthermore, we investigate the possibility of eavesdropping from the outside of such a simulation and introduce a general attack that can circumvent attempts at using quantum cryptography inside the simulation, even if the quantum properties of the simulation are genuine.