RESUMEN
Two sets of ultraviolet images of the Jovian north aurora were obtained with the Faint Object Camera on board the Hubble Space Telescope. The first series shows an intense discrete arc in near corotation with the planet. The maximum apparent molecular hydrogen emission rate corresponds to an electron precipitation of approximately 1 watt per square meter, which is about 30,000 times larger than the solar heating by extreme ultraviolet radiation. Such a particle heating rate of the auroral upper atmosphere of Jupiter should cause a large transient temperature increase and generate strong thermospheric winds. Twenty hours after initial observation, the discrete arc had decreased in brightness by more than one order of magnitude. The time scale and magnitude of the change in the ultraviolet aurora leads us to suggest that the discrete Jovian auroral precipitation is related to large-scale variations in the current system, as is the case for Earth's discrete aurorae.
RESUMEN
Health care professionals frequently ask questions about how medical devices reach the market. These questions stem partly from their concerns about the "lengthiness" of the process. Because there appear to be some misconceptions about the process as required by law, nurses and physicians may find it useful to understand how the Food and Drug Administration (FDA) enforces its laws, how it works with user communities to identify trends and problems with medical devices, and how it develops and implements educational programs to complement its enforcement responsibilities. The purpose of this article, therefore, is to explain the FDA's role in regulating medical devices, the responsibilities of manufacturers in complying with the laws which regulate getting safe and effective devices to market, and the role of health care professionals in reporting adverse incidents to the FDA to ensure the safe and effective use of this equipment.