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Regional air carriers have grown from localized, smallscale operations in the early 1960s to national operations in the 1980s. Their expansion results from an interplay of technology, route networks, and regulation policy. Government policy on regulation first assigned regions in the 1960s and then, in the 1970s, promoted entry to trunk transcontinental routes. The initial concept of the air transport region must therefore be revised, as the role of the regional carriers now approaches that of the trunk carriers. Regulation remains a key determinant of market share, and deregulation could accelerate the convergence of regional and trunk carriers.
Dans les années soixantes, les lignes aériennes régionales n'entreprenaient que des activités locales, à petite échelle. Présentement, ces měmes lignes fonctionnent, de plus en plus, comme sociétes nationales. L'élargissement de ces lignes provient de l'interaction de plusieurs facteurs, en particulier la technologie, les réseaux aériens et la politique du gouvernement. Cette dernière a permis aux lignes régionales de passer, en 1970, d'un rle local à une présence nationale. Par conséquent, le concept original d'une région aérienne doit ětre revisé, puisque le rle de la ligne régionale s'approche de plus en plus de celui de la société nationale. La part du marché de chaque type de société se détermine par la réglementation imposée par le gouvernement, et la déréglementation pourrait accelerer la convergence des rles des sociétés régionales et nationales.  相似文献   
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An unusual coarse, shelly sedimentary unit is found elevated above present mean sea level in a sheltered pocket embayment at Old Punt Bay in south‐eastern Australia. The coarse sediments, diverse microfauna, and large shelly macrofauna of mixed affinity suggest that the deposit is the result of high‐energy deposition. The deposit was previously thought to have been deposited 1000–1300 cal bp based on one shell dated using 14C and amino acid racemisation. However, additional 14C dating indicates a likely age of ~2500 cal bp . Regardless of age constraints, the presence of rock‐encrusting oyster shells and large articulated bivalves, suggests that the depositional event must have been capable of removing and transporting coarse sediments (rock clasts), bivalves, and oysters shells from a variety of seaward environments and depositing them with little abrasion, something storm waves are unlikely to do. The deposit may be tsunamigenic. If a tsunami origin is accepted, the new dating results indicate that it is possibly coeval with a tsunami event previously reported to have affected several other sites along the coast of New South Wales at c. 2900 cal bp . Consequently, this deposit provides evidence for the event at a new site and importantly, a tighter constraint on the likely date of the events occurrence. It further adds weight to the developing catalogue of palaeotsunamis that may have affected the south‐eastern coast of Australia. Regardless of the deposit's origins, if viewed from a coastal planning perspective, this deposit indicates that this part of the coast has experienced large‐scale overwash events in the past that if repeated, would be catastrophic. There are serious implications for risk management.  相似文献   
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