5,146 research outputs found

    NASA TLA workload analysis support. Volume 1: Detailed task scenarios for general aviation and metering and spacing studies

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    The techniques required to produce and validate six detailed task timeline scenarios for crew workload studies are described. Specific emphasis is given to: general aviation single pilot instrument flight rules operations in a high density traffic area; fixed path metering and spacing operations; and comparative workload operation between the forward and aft-flight decks of the NASA terminal control vehicle. The validation efforts also provide a cursory examination of the resultant demand workload based on the operating procedures depicted in the detailed task scenarios

    State promotion of local public goods: The case of public libraries, 1880-1929

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    The public library movement of the late nineteenth and early twentieth centuries led to a significant expansion of library services across the United States. We study the impact of state-level institutional development on the creation of local public goods. State library commissions were modestly funded state entities charged with helping localities establish libraries. State library associations were voluntary organizations with a similar mission, having as members the librarians of existing public libraries. Library-enabling legislation clarified the legality and taxation possibilities for local government entities such as towns, municipalities and counties to support libraries. Employing panel data drawn from a series of detailed reports on public libraries conducted by the U.S. Bureau of Education, we use a difference-in-differences methodology to identify the impact of commissions, associations, and enabling legislation on library development in matched pairs of counties that straddle state borders. Our results suggest that state-level institutions and legislation had a statistically and economically significant effect on public library development. The finding has implications for future interpretations of the history of the United States as a “nation of joiners”; local civic engagement and associational life was importantly influenced by larger scale civic and political action. JEL classifications: H40, H75, N31, N32, N41, N4

    Public libraries and political participation, 1870-1940

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    The public library movement of the late 19th and early 20th centuries fostered a rapid increase in the number and quality of public libraries in cities and towns across the United States. One important argument for libraries was that they would enhance American democracy by promoting virtues of citizenship and enabling access to information. This paper examines how voter turnout was affected, in the short-term, by the establishment of public libraries, using a county-by-election year panel. Our empirical strategy exploits the founding dates of public libraries as discrete events that should have influenced subsequent voting behavior. Over the wide range of specifications considered, the vast majority of regression results suggest that libraries had no significant short term impact on voter turnout. We discuss potential reasons for this finding, and compare it with recent work finding a positive impact of newspapers on political participation. JEL classifications: H40, H75, N31, N32, N41, N4

    Stewardship Contracting in the Siuslaw National Forest

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    The Decline and Rise of Interstate Migration in the United States: Evidence from the IPUMS, 1850-1990

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    We examine evidence on trends in interstate migration over the past 150 years, using data from the Integrated Public Use Microdata Series of the U.S. Census (IPUMS). Two measures of migration are calculated. The first considers an individual to have moved if she is residing in a state different from her state of birth. The second considers a family to have moved if it is residing in a state different from the state of birth of one of its young children. The latter measure allows us estimate the timing of moves more accurately. Our results suggest that overall migration propensities have followed a U-shaped trend since 1850, falling until around 1900 and then rising until around 1970. We examine variation in the propensity to make an interstate move by age, sex, race, nativity, region of origin, family structure, and education. Counterfactuals based on probit estimates of the propensity to migrate suggest that the rise in migration of families since 1900 is largely attributable to increased educational attainment. The decline of interstate migration in the late nineteenth century remains to be explained.

    On-line diagnosis of unrestricted faults

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    A formal model for the study of on-line diagnosis is introduced and used to investigate the diagnosis of unrestricted faults. A fault of a system S is considered to be a transformation of S into another system S' at some time tau. The resulting faulty system is taken to be the system which looks like S up to time tau, and like S' thereafter. Notions of fault tolerance error are defined in terms of the resulting system being able to mimic some desired behavior as specified by a system similar to S. A notion of on-line diagnosis is formulated which involves an external detector and a maximum time delay within which every error caused by a fault in a prescribed set must be detected. It is shown that if a system is on-line diagnosable for the unrestricted set of faults then the detector is at least as complex, in terms of state set size, as the specification. The use of inverse systems for the diagnosis of unrestricted faults is considered. A partial characterization of those inverses which can be used for unrestricted fault diagnosis is obtained

    A case of the Rodriguez Villegas conjecture

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    Let L be a number field and let E be any subgroup of the units O_L^* of L. If rank(E) = 1, Lehmer's conjecture predicts that the height of any non-torsion element of E is bounded below by an absolute positive constant. If rank(E) = rank(O_L^*), Zimmert proved a lower bound on the regulator of E which grows exponentially with [L:Q]. Fernando Rodriguez Villegas made a conjecture in 2002 that "interpolates" between these two extremes of rank. Here we prove a high-rank case of this conjecture. Namely, it holds if L contains a subfield K for which [L:K] >> [K:Q] and E contains the kernel of the norm map from O_L^* to O_K^*

    Torture and Legitimacy

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    George W. Bush’s administration has undermined the legitimacy of the United States of America as a member of the international community through an astonishing array of unilateral policies that do not respect the interests and concerns of that community. On matters of serious concern to the peoples of the world, such as the global environment, human rights, nuclear weapons proliferation, terrorism, and, of course, war, the United States has pursued its foreign policy interests guided by “political realism” and a stubborn commitment to its narrowly interpreted national interests. It is not enough, however, to merely identify and condemn the legitimacy crisis of the United States; action is required to bring it into alignment with the laws of the international community. Responsibility for that action belongs to the American people. Action sufficient to restore U.S. legitimacy would include the reclamation of our democratic political structures, as well as public acts that denounce torture
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