7,399 research outputs found
Upper Bound on the Dark Matter Total Annihilation Cross Section
We consider dark matter annihilation into Standard Model particles and show
that the least detectable final states, namely neutrinos, define an upper bound
on the total cross section. Calculating the cosmic diffuse neutrino signal, and
comparing it to the measured terrestrial atmospheric neutrino background, we
derive a strong and general bound. This can be evaded if the annihilation
products are dominantly new and truly invisible particles. Our bound is much
stronger than the unitarity bound at the most interesting masses, shows that
dark matter halos cannot be significantly modified by annihilations, and can be
improved by a factor of 10--100 with existing neutrino experiments.Comment: 4 pages, 3 figures; version accepted for publication in PR
Industrial competitiveness of the auto parts industries in four large Asian countries : the role of government policy in a challenging international environment
Rationalization and stabilization following the Asian financial crisis of the late 1990s combined with the expansion and liberalization of regional and global trade to create significant parts industries in China, Indonesia, and the Republic of Korea. Conventional policies of stabilization and liberalization, however, cannot fully explain growth patterns. Japan and Korea grewinto major players before liberalizing trade and investment, while even after extensive liberalization Indonesia has yet to move from extensive to intensive growth. These anomalies suggest that to explain success in the auto parts industry we need to move beyond liberalization to look at policies and institutions promoting economies of scale, skill formation, quality upgrading, supplier-linkage cooperation, and innovation. In Japan, the regional and global leader, innovative assemblers led industrial development and supported key suppliers, but the government also supported diffusion of quality control techniques and new technology to small and medium enterprises, and encouraged stable employment among core employees. Korea remains weaker on both small and medium enterprise and employment fronts, but government-encouraged consolidation around a small number of business groups, an extended period of protection, and support for export promotion led to economies of scale. Liberalization of foreign investment after the financial crisis helped ameliorate the excessive statism of earlier policies and strengthened the parts industry. In China, liberalization for WTO entry, rapid expansion in demand, and strong support by local governments encouraged a wave of foreign investment in both assembly and parts. In contrast, institutional weaknesses continue to constrain development opportunities in Indonesia.Technology Industry,Economic Theory&Research,Water and Industry,Markets and Market Access,Non Bank Financial Institutions
Artificial Intelligence (AI), Operations Research (OR), and Decision Support Systems (DSS): A conceptual framework
In recent years there has been increasing interest in applying the computer based problem solving techniques of Artificial Intelligence (AI), Operations Research (OR), and Decision Support Systems (DSS) to analyze extremely complex problems. A conceptual framework is developed for successfully integrating these three techniques. First, the fields of AI, OR, and DSS are defined and the relationships among the three fields are explored. Next, a comprehensive adaptive design methodology for AI and OR modeling within the context of a DSS is described. These observations are made: (1) the solution of extremely complex knowledge problems with ill-defined, changing requirements can benefit greatly from the use of the adaptive design process, (2) the field of DSS provides the focus on the decision making process essential for tailoring solutions to these complex problems, (3) the characteristics of AI, OR, and DSS tools appears to be converging rapidly, and (4) there is a growing need for an interdisciplinary AI/OR/DSS education
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