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Biomedical subjects

D A Irwin

Publications and source records attributed to D A Irwin.

14 recordsLinked to original sources

Sematech: purpose and performance.

In previous research, we have found a steep learning curve in the production of semiconductors. We estimated that most production knowledge remains internal to the firm, but that a significant fraction "spills over" to other firms. The existence of such spillovers may justify government actions to stimulate research on semiconductor manufacturing technology. The fact that not all production knowledge spills over, meanwhile, creates opportunities for firms to form joint ventures and slide down their learning curves more efficiently. With these considerations in mind, in 1987 14 leading U.S. semiconductor producers, with the assistance of the U.S. government in the form of $100 million in annual subsidies, formed a research and development (R&D) consortium called Sematech. In previous research, we estimated that Sematech has induced its member firms to lower their R&D spending. This may reflect more sharing and less duplication of research, i.e., more research being done with each R&D dollar. If this is the case, then Sematech members may wish to replace any funding withdrawn by the U.S. government. This in turn would imply that the U.S. government's contributions to Sematech do not induce more semiconductor research than would otherwise occur.

Costs and Cost Analysis↗

An injury-induced diffuse slow potential from brain.

Three different slow potential (SP) changes resulting from focal brain injury are described. The first is an immediate, high amplitude (in excess of 25 mV)negative shift at the site of injury. The second is a biphasic negative-positive SP wave which spreads throughout the cortex ipsilateral to injury and is similar to spreading depression (SD). The third SP change, called here the injury-induced diffuse slow potential (IDSP)is a prolonged (lasting approx. 2h) negative shift occurring simultaneously in many brain areas, also in those far removed from the injured focus. The SD can be separated from IDSP by the size of focal injury; a 20 mu pucture of the parenchyma will trigger IDSP but not SD. An injury resulting from a larger puncture triggers both, SD and IDSP. IDSPcan not be induced by a re-entry of a previously damaged tissue. The magnitude of IDSP has anatomical specificity in that the largest amplitude occurrs in white as compared to gray of the cortex or of the caudate nucleus. Aso, the magnitude of the hypothalamic IDSP is larger when ipsilateral corpus callosum-commissural regions are injured. Electrical stimulation of the cortex in rats sufficiently strong to result in tonic-clonic convulsions triggers SD and IDSP; these two slow potential changes are similar to those induced by mechanical injury. A transpinnate electrical stimulus strong enough to elicit a grand-mal type of discharge results in a diffuse negative slow potential change similar to IDSP elicited by mechanical damage or direct cortical stimulation.

Animals↗

Spontaneous whole brain slow potential changes during recovery from experimental neurosurgery.

Prolonged, nonlocalized brain slow potential changes, frequently associated with cortical spreading depression, occur spontaneously during 5 days following brain implant surgery in rats. These potentials are accompanied by reductions in multiple nerve cell activity and reductions in behavioral motility. The method used in this study provides a tool for evaluating recovery from neurosurgical trauma or other brain injuries, and for testing procedures that facilitate or impede this process.

Animals↗