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Explanations for national success in science and technology typically focus on domestic institutions and policies. However, that line of research has yet to identify any particular set of institutions or policies that explain variation in national innovation rates across cases or over time. This article offers new evidence that the problem with domestic institutions approaches stems from their failure to consider international security factors. Specifically, this article finds a positive effect for U.S. security alliances on innovation. This finding is robust across different specifications and periods of analysis. While countries that ally militarily with the United States are found to realize benefits in economy‐wide, indigenous innovation, such an effect is not observed in military technologies. This suggests that alliances may substitute for being on the frontier in military technologies. Therefore, this article contributes not just to debates over S&T competitiveness, but also to alliance formation.  相似文献   
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Merton’s concept of “middle range theories” has been widely accepted as one of his most influential contributions to sociological terminology, even if there is no conclusive understanding of its semantic and methodological meaning. The article proposes to ignore the term. On the one hand, it cannot be logically clarified and, on the other, it restrains an appropriate judgement of the merits of Merton’s research programme.  相似文献   
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Farmer-to-farmer extension (FFE) is playing a complementary role to formal extension services in facilitating the spread of agricultural technologies and improving farmers’ capacities. The effectiveness and sustainability of such programmes depend on volunteer farmer trainers (VFTs) having technical skills and overcoming process-related challenges that hinder them from achieving the desired outcomes. This article uses quantitative and qualitative data collected from seven sites to explore the challenges experienced by VFTs as they share their knowledge on livestock feed innovations in a dairy development project in Kenya. Sustainable opportunities for enhancing VFTs’ performance are discussed.  相似文献   
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Postmortem stability of DNA   总被引:11,自引:0,他引:11  
High-molecular-weight DNA was recovered postmortem in sufficient quantities from various human organ tissues as well as from blood, although not all organs were equally well suitable. Good DNA stability was found in brain cortex, lymph nodes and psoas muscle over a period of three weeks postmortem. Spleen and kidney showed good DNA stability up to five days postmortem but after longer periods, rapid degradation was observed. Yields of DNA from blood were not consistent because of the non homogeneity of samples. Blood clots were rich with DNA. Generally, the amount of degraded DNA correlated directly with the duration of the postmortem period. However in some cases, DNA degradation was already prominent after a short period. However in some cases, DNA degradation was already prominent after a short period. Case histories showed that high environmental temperature at the site of death and/or infectious diseases prior to death were the main factors for rapid autolysis. Gradual disappearance to complete loss of the long fragments (15-23 kb) was observed in DNA fingerprinting using the minisatellite probe 33.15. No extra-bands were noted, thus excluding erroneous conclusions. However, evidentiary value of older samples was lower.  相似文献   
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The allele frequency distribution of 15 short tandem repeats (STR) loci contained in the AmpFlSTR Identifiler PCR Amplification Kit (Applied Biosystems), was determined in two Berber populations from Asni and Bouhria, in Central and Eastern Morocco, respectively. A total of 209 individuals were typed. No deviations from the Hardy-Weinberg equilibrium were observed for Asni at the 15 STRs loci whereas for the Bouhria samples, two loci (D5S818 and TH01) showed significant departures from Hardy-Weinberg expectations (after Bonferroni's correction). All loci are highly polymorphic and population differentiation tests showed that the Moroccan samples from Asni and Bouhria have significant differences in 4 out of 15 loci (D21S11, D7S820, D16S539 and TPOX). The aim of the study was to obtain accurate allele frequencies relevant for forensic applications. Comparative analyses between our population data and other population samples gathered from the literature are also presented.  相似文献   
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