Abstract: A surgical navigation method utilizing a computer system. The method includes the steps of: (a) fixing a camera relative to a surgical site on a patient such that the camera does not move relative to the surgical site; (b) restraining the body portion of the patient which includes the surgical site relative to an operating table supporting the patient, such that the body portion does not move relative to the operating table; and (c) detecting with the camera the position of a medical instrument having a tracker array.

Abstract: An apparatus is described comprising a current source and a pair of transistors coupled to the current source. A pair of variable loads are coupled to the pair of transistors such that a first of the pair of transistors drives a first of the pair of variable loads and a second of the pair of transistors drives a second of the pair of variable loads. Each of the pair of variable loads are coupled to a high gain input and a low gain input. Another apparatus is described comprising an oscillator having a high gain input and a low gain input. The oscillator comprises a series of inverters where each inverter output is coupled to the next inverter input in the series. At least one of the inverters comprises a current source and a pair of transistors coupled to the current source.

Abstract: A method for loading particles, such as coal, into a plurality of railroad cars wherein a control weight of a railroad car loaded with particles is established. Each of the railroad cars is weighed prior to loading particles into the railroad car from a weigh bin to determine an unfilled weight of each railroad car and the unfilled weight of each railroad car is compared with the control weight to determine an unfilled differential weight for each railroad car. The particles are loaded into the weigh bin from a surge bin and the surge bin is weighed as the particles are being loaded into the weigh bin from the surge bin so the loading of particles into the weigh bin can be terminated when a weight of particles has been loaded into the weigh bin about equal to and less than the unfilled differential weight associated with the railroad car to be loaded with the unfilled differential weight of particles.