3,577 research outputs found

    Development of advanced digital techniques for data acquisition processing and communication Interim scientific report

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    Digital techniques for automatic evaluation of images and data compression algorithm

    Command system study for the operation and control of unmanned scientific satellites, task III - Command system interference Third quarterly progress report, 1 Jan. - 31 Mar. 1965

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    Effects of CW and modulated interference on baseband of AM and FM demodulators used for control of unmanned scientific satellite

    Nicotine Dependence as a Mediator of Project EX's Effects to Reduce Tobacco Use in Scholars.

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    In Spain, 44% of 14-18-year-olds have smoked, and 12.5% have smoked cigarettes in the last 30 days. Nicotine is one of the most addictive substances, and can lead to serious addiction in adulthood with adverse consequences to one's health. School plays a relevant role in health promotion and preventing risk behaviors such as tobacco consumption. Despite the fact that some school-based tobacco cessation and prevention interventions prove to be effective for their purposes, there is a lack of understanding as to why these programs succeed or fail. This longitudinal study aims to test the nicotine dependence (ND) as a mediator of Project EX's effect - a tobacco-use cessation program developed for high school youth to reduce tobacco consumption in scholars. Six high schools located in the Mediterranean coast were randomized for the participation of the program (Spanish version of Project EX) or a waiting-list group with baseline, immediate-posttest, and 12-month follow-up assessments. At baseline, 1,546 adolescents aged 14-21 years old (mean age: 15.28; SD = 1.20; 46% were women) were evaluated by self-administered tests on tobacco consumption and ND. A biomarker of smoke inhalation - a measurement of exhaled carbon monoxide (ECM) - was used. Participants who were smokers (N = 501; 32%) were selected for this study. Mediation analyses were conducted using the PROCESS v2.12 macro for Windows. The significant criterion was p ≤ 0.05, and 5,000 samples were used for bias-corrected bootstrap confidence intervals. Results indicated that Project EX indirectly decreased the number of cigarettes smoked in the last month, the number of cigarettes smoked within the last 7 days, the number of daily cigarettes, and ECM level at 12-month follow up through decreasing the level of ND in the short-term. This is the first Spanish study that explores ND as a mediator of the long-term efficacy of Project EX to reduce tobacco consumption in adolescents. Results suggest that interventions that reduce ND at short-term are more likely to be successful to decrease tobacco use at long-term

    One-Year Effects of Project EX in Spain: A Classroom-Based Smoking Prevention and Cessation Intervention Program.

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    BackgroundTobacco use prevalence rates are high among Spanish adolescents. Programming to counteract tobacco use is needed.Methods and findingsThe current study provides a one-year follow-up outcome evaluation of Project EX, an eight-session classroom-based curriculum. The intervention was tested using a randomized controlled trial with 1,546 Spanish students, involving three program and three control schools. Compared to the control condition, the program condition revealed a greater reduction in nicotine dependence (p < .05) and CO ppm levels (p < .001), and lower consumption of cigarettes at last month (p = .03).ConclusionsLong-term outcomes of the Project EX classroom-based program are promising for adolescent prevention and possibly cessation in Spain

    Promoting the Concept of Sustainable Transportation within the Federal System - The Need to Reinvent the U.S. DOT

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    This paper argues that a major obstacle to progress towards sustainable development/transportation is the lack of an integrated approach to decision-making within the U.S. federal system. To address this problem, the concept of sustainable transportation is first broadened to include the transportation sector’s interconnections with other sectors. This revised notion of sustainable transportation is then used to help visualize the need for horizontal integration and co-optimization of policies/regulations/initiatives across federal agencies. From the assumption that a national strategy for sustainable development will remain illusive in the short-term, a ‘U.S. DOT reinvention model’ is endorsed as a useful mechanism to promote sustainable development/transportation policy in the U.S

    Simulating the Impact of Strategy Development Frameworks on Transportation Infrastructure System Performance

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    This paper develops, through a simulation model, a deeper understanding of the relationship between transportation infrastructure strategy development frameworks and system performance. A strategy development framework for transportation can be characterized by the infrastructure ownership structures, cross-modal and cross-sectoral linkages, revenue sources, resource allocation decision-making processes, and geographic scales of the organizations responsible for making infrastructure investments. Taking the dimensions of a strategy development framework as inputs, the model simulates investments in an infrastructure network over time—in this paper, the national intercity roadway network of Portugal. The results demonstrate the value of using simulation models of complex transportation systems to inform the decisions of not only planners but also of stakeholders who design strategy development frameworks. Such a tool is particularly important given the ongoing reorganizations of the Portuguese transportation sector, including increasing reliance on concession agreements, highway tolls, and sub-national government participation

    Evolution of radial profiles in regular Lemaitre-Tolman-Bondi dust models

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    We undertake a comprehensive and rigorous analytic study of the evolution of radial profiles of covariant scalars in regular Lemaitre-Tolman-Bondi dust models. We consider specifically the phenomenon of "profile inversions" in which an initial clump profile of density, spatial curvature or the expansion scalar, might evolve into a void profile (and vice versa). Previous work in the literature on models with density void profiles and/or allowing for density profile inversions is given full generalization, with some erroneous results corrected. We prove rigorously that if an evolution without shell crossings is assumed, then only the 'clump to void' inversion can occur in density profiles, and only in hyperbolic models or regions with negative spatial curvature. The profiles of spatial curvature follow similar patterns as those of the density, with 'clump to void' inversions only possible for hyperbolic models or regions. However, profiles of the expansion scalar are less restrictive, with profile inversions necessarily taking place in elliptic models. We also examine radial profiles in special LTB configurations: closed elliptic models, models with a simultaneous big bang singularity, as well as a locally collapsing elliptic region surrounded by an expanding hyperbolic background. The general analytic statements that we obtain allow for setting up the right initial conditions to construct fully regular LTB models with any specific qualitative requirements for the profiles of all scalars and their time evolution. The results presented can be very useful in guiding future numerical work on these models and in revising previous analytic work on all their applications.Comment: Final version to appear in Classical and Quantum Gravity. Readers eager to know the results and implications without having to go through the technical detail are recommended to go directly to the summary and discussion in the final section (section 11). Typos have been corrected and an important reference has been adde
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