Drivers under the age of 70 whose prior 4-year accident and conviction records showed no entries when examined 2 months prior to the date of expiration of their driver licenses were randomly assigned to either a group that renewed licenses in the normal manner or a group that was offered the opportunity to receive a 4-year license extension by mail. A related experiment involved comparing clean-record drivers of any age who were given a 2-year extension with a group of drivers required to renew in person. Examination of driver records 18 and 28 months subsequent to extension uncovered no deleterious effects of the program, while savings of roughly 3 million dollars annually are expected. Findings are tentative, however, until 4-year data can be collected. The report concludes that the extension program has been successful, that multiple extensions should be authorized and evaluated for drivers with continuing clean records, and that the present exclusion of drivers 70 and above does not appear to be defensible. 相似文献
“The impact of ISO 14000 will be swift and significant. For businesses exporting to global markets, and their suppliers, preparing for ISO 14000 today is not an option—it's a matter of survival…”. 相似文献
DESIGN ON THE LAND: the development of Landscape Architecture Norman T. Newton Belknap Harvard
COMMUNITY CENTERS AND STUDENT UNIONS Eugene D. Sternberg and Barbara E. Sternberg Van Hostrand Reinhold Company, New York.
DECISION AND CONTROL by Stafford Beer, John Wiley and Sons, Inc., New York, 1966 (3rd printing, 1970)
INDUSTRIAL DYNAMICS by Jay W. Forrester, M.I.T. Press, Cambridge, Mass., 1961. S.1O.5O.
PRINCIPLES OF SYSTEMS by Jay W. Forrester. Wright‐Allen Press, Inc., Cambridge, Mass., 1968.
PUBLIC INQUIRIES AS AN INSTRUMENT OF GOVERNMENT R.E. Wraith and G.B. Lamb George Allen & Unwin Ltd. for the Royal Institute of Public Administration, London 1971, £4.50.
SYSTEMS APPROACH AND THE CITY M.D. Mesarovic and A. Reisman (eds.) North‐Holland Publishing Co., Amsterdam and London, 1972.
SIMULATION IN THE CLASSROOM John L. Taylor and Rex Walford Penguin Books, London, 1972. 45p.
DEVELOPMENT BUILDING: THE TEAM APPROACH C.W. Griffin John Wiley & Sons, Inc. for the American Institute of Architects, New York, 1972.相似文献
Over half of the European landscape is under agricultural management and has been for millennia. Many species and ecosystems of conservation concern in Europe depend on agricultural management and are showing ongoing declines. Agri‐environment schemes (AES) are designed partly to address this. They are a major source of nature conservation funding within the European Union (EU) and the highest conservation expenditure in Europe. We reviewed the structure of current AES across Europe. Since a 2003 review questioned the overall effectiveness of AES for biodiversity, there has been a plethora of case studies and meta‐analyses examining their effectiveness. Most syntheses demonstrate general increases in farmland biodiversity in response to AES, with the size of the effect depending on the structure and management of the surrounding landscape. This is important in the light of successive EU enlargement and ongoing reforms of AES. We examined the change in effect size over time by merging the data sets of 3 recent meta‐analyses and found that schemes implemented after revision of the EU's agri‐environmental programs in 2007 were not more effective than schemes implemented before revision. Furthermore, schemes aimed at areas out of production (such as field margins and hedgerows) are more effective at enhancing species richness than those aimed at productive areas (such as arable crops or grasslands). Outstanding research questions include whether AES enhance ecosystem services, whether they are more effective in agriculturally marginal areas than in intensively farmed areas, whether they are more or less cost‐effective for farmland biodiversity than protected areas, and how much their effectiveness is influenced by farmer training and advice? The general lesson from the European experience is that AES can be effective for conserving wildlife on farmland, but they are expensive and need to be carefully designed and targeted. 相似文献
Summary The three age-sex classes of rufous hummingbirds (Selasphorus rufus) that directly interact on southward migratory stopovers in our California study system differ in territorial ability and resource use. Immature males are behaviorally dominant to adult and immature females and defend the richest territories. Here, we test the hypothesis that the territorially subordinate age-sex classes compensate exploitatively for their exclusion from rich resources. Our results show that females were able to accumulate energy stores at rates comparable to males despite their subordinate territorial status. Territorial females gained body mass at the same rate and in the same pattern as males, and resumed migration at the same body masses. Moreover, during periods when birds were nonterritorial and used dispersed resources, adult and immature females maintained or gained body mass, whereas immature males lost mass. We suggest that females may be energetically compensated by (1) lower costs of flight incurred during foraging and defense, resulting from their lower wing disc loading, and (2) greater success at robbing nectar from rich male territories, resulting from duller coloration (immature females), experience (adult females), and, possibly, hormonal differences. In the future, experiments will be necessary to distinguish the various hypotheses about the mechanisms involved in compensation.
Correspondence to: F.L. Carpenter 相似文献