In addition to judging United States competitiveness by comparing investments worldwide, the NNAP sought to compare research output. However, it is important to keep in mind that patents and publications are based on research that was performed one or more years prior to submission, with additional time elapsed between the submission of the research and its publication. Just as research spending precedes discovery and innovation, these measures lag behind.

　

 One metric often used to gauge scientific leadership is the number of peer-reviewed scientific articles. Figure 2 shows the results of a search of one of the principal databases of scientific literature, the Institute for Scientific Information (ISI) Web of Science a searchable database of about 5400 professional journals, using the keyword "nano^*." The chart shows an escalation in the total number of publications since 1989, and especially since 2000. Although the number of publications from the United States has grown throughout the period, the percentage of publications originating from the United States has declined from approximately 40% in the early 1990s to less than 30% in 2004. In a similar study, Zucker and Darby (2005) show that the United States is dominant in terms of the number of nanotechnology research articles published, accounting for more than twice the number published by the country with the next-highest number, China. However, Zucker and Darby also note that the U.S. share is decreasing. They summarize: "Taken as a whole these data confirm that the strength and depth of the American science base points to the United States being the dominant player in nanotechnology for some time to come, while the United States also faces significant and increasing international competition."

　

　

 Whereas the total number of publications is an indicator of the quantity of research output, a better indicator of the quality of the output is represented by publication in the most highly regarded and widely read scientific journals. A search of three high impact journals, Science, Nature, and Physical Review Letters, shows a 100% increase in the percentage of articles related to nanotechnology in these journals. Among these publications, the United States has produced an even larger fraction―over 50%―of the nanotechnology-related articles (Figure 3). These data show, however, as did those from the broader selection of publications, that there is a steady increase in the percentage that originates from other countries.

　

 Another metric commonly used to gauge leadership in technology innovation, and one that is perhaps more indicative of movement toward a commercial application, is the number of patents and patent applications. A study by Huang et al. (2004) reveals the rapid growth of nanotechnology-related patents. Based on a search of the full text of patents in the U.S. Patent and Trademark Office (USPTO) database using a list of nanotechnology-related keywords, over 8,600 nanotechnology-related patents were issued in 2003, an increase of about 50% over the number issued in 2000. The analysis pointed to strong U.S. leadership in the number of patents issued. U.S. entities accounted for over 60% of nanotechnology patents recorded in the USPTO database during the years 1976 to 2003. In addition, among the patents identified by the study, U.S. patents received the most citations by subsequently filed patents, another indication of technology leadership. Overall, the five countries receiving the highest number of nanotechnology-related patents in 2003 were the U.S. (5,228), Japan (926), Germany (684), Canada (244) and France (183). The number of nanotechnology-related patents issued by the USPTO to assignees in other countries, especially the Netherlands, Korea, Ireland, and China, is likewise increasing.

　

 Because a full-text search finds patents that mention nanotechnology-related terms in the background section of the patent, even though the patented invention itself does not necessarily meet the definition of nanotechnology, Huang et al. also performed a search of just the patent title and claims. The results of this search for the years between 1990 and 2003 (shown in Figure 4) show trends that are similar to those indicated by the broader full-text search.

　

　

　

 The preceding sections indicate that the United States has a leadership position in terms of total investment, research publications, and patents related to nanotechnology. In addition to these overall measures, an accurate assessment of U.S. competitiveness requires the identification of countries that have adopted a strategy of making targeted investments, thereby positioning themselves to be leaders in a key industry or platform technology.

　

 In June 2004, NSF sponsored an international meeting on responsible nanotechnology research and development at which 25 countries and the European Union were represented. Attendees were asked to provide estimates of government funding and areas of particular research interest. Results of this survey indicated that some nations have broad research programs, like the United States, whereas others have opted to make targeted research investments. Table 3 shows the key areas in which various countries are focusing their nanotechnology efforts according to the survey responses. These countries appear to be investing especially in materials/manufacturing, biotechnology, and electronics.

　

 According to reports from the Asian Technology Information Program (ATIP), which tracks activity among Asian Pacific nations, China is especially strong in nanomaterials development. China's nanomaterials research focus, its low cost of doing business, its talented labor pool, and its potentially large domestic market, could provide incentive for further investment by foreign corporations seeking to capitalize on nanomaterials development (ATIP 2003; ATIP 2004). Other Asian countries are likewise focusing nanotechnology research efforts on industries in which they already hold a comparative advantage. According to ATIP, Korea is focusing on nanoelectronics with strong industry participation, Taiwan is targeting nanoelectronics, and Singapore has a particular emphasis on nanobiotechnology. Taiwan's National Science Council, which administers government funding for Taiwan's nanotechnology effort, plans to establish three technology research parks;

　

　

 Two would focus on nanoelectronics research. Though Japan has the strongest government support for nanotechnology research in the region, with broad scope, its recognized strength is in infrastructure and instrumentation. Japan also is focused particularly on the commercialization of nanotechnology; recently a number of new initiatives were launched to assist Japanese businesses and to develop strategies aimed at creating new nanotechnology-related industries. As part of a larger S&T strategy, the Japanese government has included the "development of new devices using nanotechnology" as one of five "leading projects" aimed at revitalizing the Japanese economy.

　

　

 In Europe, efforts exist at both at the national level, with a number of individual countries pursuing targeted research, and at the European Commission (EC) level, with a more broad-based program. For example the EC, under its 6th Framework Programme for Research and Technological Development, committed about 350 million euros for nanotechnology funding in 2003, which represents a third of the overall European expenditure. In a recent communication (Commission of the European Communities 2004), the European Commission endorsed a more coordinated approach to nanotechnology R&D across EU countries while acknowledging the multiple individual country programs that already exist. Germany's strategic investment can be traced to the early 1990s, when nanotechnology was identified as a field with substantial promise. As a result of sector forecasting studies commissioned by the government, over the years Germany has developed a strategy to prioritize the majority of its Federal funding toward nanoelectronics, nanoscale materials, and optical science and engineering (OECD 2002; see also Table 4). In addition to funding for R&D, German public funding is targeting infrastructure development, including research centers at various geographic locations. While the EU as a whole appears to be competing for broad nanotechnology research leadership, some of the targeted research being conducted in particular EU countries could also provide competitive advantages in particular technologies or industry sectors. NNAP recommends the close monitoring of the EU's coordinated effort and the nanotechnology initiatives of individual EU countries.