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This paper reports upon the
profitability of firms that locate their headquarters in same-industry
or clusters and those that opt to maintain headquarters in other locations.
While the preponderance of the theoretical and descriptive literature
emphasizes the potential benefits associated with clustering, some papers
suggest that clustering should not be
beneficial, at least for particular types of firms in particular circumstances.
This empirical study, which examines a sample of more than 4000
Compustat firms from 86 different industries, compares the profitability of
firms in industry clusters and firms in other locations. The sample is
partitioned into small and large firms to account for expected differences in
profitability, in general, and the possible differential impact of geographic
clustering. The results
show that for smaller firms, the profitability of cluster members tends to be
considerably lower than for firms that opt not to join clusters. For the
subsample of larger firms, the results are mixed depending upon the measure of
results imply that smaller firms should carefully evaluate the decision to
locate in industry clusters.
The biomedical hypothesis proposed here is that the immediate trigger for a yawn is a restricted collapse of a few alveoli in the lungs. The extent of this alveolar collapse may be too small for it to be detected by current X-ray technology, but this technology is continually improving and may soon be good enough to test the hypothesis. In support of the hypothesis, it is shown that yawning can be inhibited by deep breaths of air, nitrogen or carbogen, thus showing that yawning is not triggered by lack of oxygen or by excess carbon dioxide, leaving alveolar collapse as the most likely possibility. A more extensive form of alveolar collapse is termed atelectasis and this involves a serious state of hypoxia which, if deepened or prolonged, can be fatal. Therefore, if the hypothesis is correct, yawning may prevent the development of atelectasis and save lives. This paper is not concerned with other indirect ways in which yawning may be induced, nor with the mechanism and neural circuitry of the yawn, nor with social aspects of yawning, only with the immediate trigger. My aim is to get better evidence for the hypothesis put forward here and also to study the behaviour of the pulmonary alveoli in normal respiration.