Research into III-Nitride based avalanche photodiodes (APDs) is motivated by the need for high sensitivity ultraviolet (UV) detectors in numerous civilian and military applications. By designing III-Nitride photodetectors that utilize low-noise impact ionization high internal gain can be realized—GaN APDs operating in Geiger mode can achieve gains exceeding 1×10. Thus with careful design, it be...

Adherens junctions (AJ) comprise a unique and widespread family of cellular contacts which displays a stable association, within the cells, with actin-containing microfilaments [Geiger et al., 19871. As discussed in several previous articles [Burridge et al., 1988; Woods and Couchman, 19881 AJ may be formed with different surfaces and assume a rather diverse morphology. They may be found in are...

As an undergraduate biology major, while I still had my sights set on a career in medicine, I began my honors thesis, a comparative health policy analysis of the United States and Sweden. It was a sort of natural experiment to observe the outcomes of universal coverage. One of the central components of my work was a model depicting the interplay between health and its social determinants. Now, ...

D igital computers and mammalian brains share not only a talent for computation but also a method that favors absolutes. The ones and zeros of a computer are analogous to the all-or-none character of action potentials in the brain. Neurons sum all incoming depolarizing signals until, at a threshold level of depolarization, an action potential fi res along the axon. Now, however, Henrik Alle and...

The advantages and limitations of Geiger counter techniques in a laboratory applying X-ray methods to a variety of problems are discussed and some simple examples are described. These illustrate the convenience of its use in obtaining semi-quantitative results very rapidly and in following the effects of various treatments. The accuracy of the method is considered in relation to the statistical...

The performance of a new kind of double gap resistive plate counter (RPC) has been studied using cosmic rays. The detector was operated with a mixture containing low percentage of isobutane. A comparison with the behaviour of RPC flowed with standard mixture is presented.