A population-based case-control study in Utah of 358 cases diagnosed with prostate cancer between 1984 and 1985, and 679 controls categorically matched by age and county of residence, were interviewed to investigate the association between dietary intake of energy (kcal), fat, protein, vitamin A, beta-carotene, vitamin C, zinc, cadmium, selenium, and prostate cancer. Dietary data were ascertained using a quantitative food-frequency questionnaire. Data were analyzed separately by age (45-67, 68-74) and by tumor aggressiveness. The most significant associations were seen for older males and aggressive tumors. Dietary fat was the strongest risk factor for these males, with an odds ratio (OR) of 2.9 (95 percent confidence interval [CI] 1.0-8.4) for total fat; OR = 2.2 (CI = 0.7-6.6) for saturated fat; OR = 3.6 (CI = 1.3-9.7) for monounsaturated fat; and OR = 2.7 (CI = 1.1-6.8) for polyunsaturated fat. Protein and carbohydrates had positive but nonsignificant associations. Energy intake had an OR of 2.5 (CI = 1.0-6.5). In these older men, no effects were seen for dietary cholesterol, body mass, or physical activity. There was little association between prostate cancer and dietary intake of zinc, cadmium, selenium, vitamin C, and beta-carotene. Total vitamin A had a slight positive association with all prostate cancer (OR = 1.6, CI = 0.9-2.4), but not with aggressive tumors. No associations were found in younger males, with the exception of physical activity which showed active males to be at an increased but nonsignificant risk for aggressive tumors (OR = 2.0, CI = 0.8-5.2) and beta-carotene which showed a nonsignificant protective effect (OR = 0.6, CI = 0.3-1.6). The findings suggest that dietary intake, especially fats, may increase risk of aggressive prostate tumors in older males.

This paper demonstrates magnetic three-degree-of-freedom (3-DOF) closed-loop position and 2-DOF open-loop orientation control of a mockup magnetic capsule endoscope in fluid with a single permanent magnet positioned by a commercial 6-DOF robotic manipulator, using feedback of only the 3-DOF capsule position measured by a localization system, with application in capsule endoscopy of a fluid-distended stomach. We analyze the kinematics of magnetic manipulation using a single permanent magnet as the end-effector of a serial-link robot manipulator, and we formulate a control method that enables the capsule's position and direction to be controlled when the robot manipulator is not in a kinematic singularity, and that sacrifices control over the capsule's direction to maintain control over the capsule's position when the manipulator enters a singularity. We demonstrate the method's robustness to a reduced control rate of 25 Hz, reduced localization rates down to 30 Hz, deviation in the applied magnetic field from that expected, and the presence of manipulator singularities. Five-DOF manipulation of an untethered magnetic device has been previously demonstrated by electromagnetic systems only.

To date, untethered magnetic devices actuated with a single rotating permanent magnet, such as active capsule endoscopes and magnetic microrobots, have been constrained to operate in positions where the rotating dipole field behavior is simple and easy to visualize. In this paper, we show how to generate a rotating magnetic field with any desired rotation axis, for magnetic device actuation, at any device position in space using a single rotatingmagnet actuator. The methods presented can control untethered rotating magnetic devices, while the rotating actuator magnet follows trajectories independent of the untethered devices themselves. We demonstrate our methods by actuating rotating magnetic devices in a lumen. Applications include minimally invasive medical tasks requiring an untethered magnetic device to operate in natural lumen pathways of the body (e.g., the gastrointestinal system, the subarachnoid space of the nervous system, or vasculature).

This paper studies the behavior of rotating magnetic microrobots, constructed with a permanent magnet or a soft ferromagnet, when the applied magnetic field rotates faster than a microrobot's step-out frequency (the frequency requiring the entire available magnetic torque to maintain synchronous rotation). A microrobot's velocity dramatically declines when operated above the step-out frequency. As a result, it has generally been assumed that microrobots should be operated beneath their step-out frequency. In this paper, we report and demonstrate properties of a microrobot's behavior above the step-out frequency that will be useful for the design and control of multi-microrobot systems. V

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