Abies nephrolepis Max. is a fir species occurring in Northeast China, the extreme southeast of Russia and Korea. In Korea, A. nephrolepis is one of only three native fir species growing in high, mountainous areas with a disjunct distribution. We investigated genetic variation in A. nephrolepis by examining 24 ISSR polymorphic loci in 248 individuals representing eight natural populations in Korea. The level of intra-population genetic diversity (H e = 0.240) was similar to or slightly lower than that of plants with similar ecological traits and life history. Most of the genetic diversity was allocated among individuals within populations (G ST = 0.082, Φ ST = 0.041) and the number of migrants per generation (N m ) was 5.56. Nei's genetic distances were small (D = 0.027) and unrelated to geographic distances between populations. Implications for the conservation of genetic variation in A. nephrolepis in South Korea were discussed. Abies nephrolepisMax. / ISSR / genetic diversity / genetic differentiation Résumé -Variabilité génétique dans des populations naturelles de Abies nephrolepis Max. en Coréee du Sud. Abies nephrolepis Max. est un sapin présent dans le Nord-Est de la Chine, l'extrême Sud-Est de la Russie et en Corée. En Corée, A. nephrolepis est une des trois espèces autochtones de sapin poussant dans des zones disjointes en haute montagne. Nous avons étudié la variabilité génétique chez A. nephrolepis grâce à 24 locus polymorphes ISSR sur un échantillon de 248 individus représentant huit populations naturelles en Corée. Le niveau de diversité génétique intra-population obtenu (H e = 0, 240) était semblable ou légèrement plus faible que celui obtenu pour des plantes avec des caractères écologiques ou une histoire semblables. La plus grande part de la diversité génétique était représentée par la variabilité entre individus dans populations (G ST = 0, 082, Φ ST = 0, 041) et le nombre de migrants par génération (N m ) était de 5,56. Les distances génétiques de Nei étaient faibles (D = 0, 027) et sans relation avec les distances géographiques entre populations. Les implications pour la conservation de la diversité génétique de A. nephrolepis en Corée du Sud sont discutées. Abies nephrolepis Max. / ISSR / diversité génétique / différenciation génétique
The fast and accurate measurement of the thickness of multiple oxide/nitride layer deposition (MOLD) films is desirable to improve the quality of the plasma deposition process and potentially simplify the metrology in 3D NAND flash memory devices. In this study, we performed deep neural network modeling of the reflectance spectrum data of two pairs of oxide/nitride films on a silicon substrate. We designed a deep neural network model to estimate the thickness of four stacked thin-film layers and the MOLD film. Principle component analysis of this model was performed to develop another model with 27 features. Finally, a combined model was designed by fine tuning both the models and applying an ensemble algorithm to both. The mean absolute error of the combined predictive model was lower than that of the individual models. We verified the performance of the proposed model by considering the thin-film deposition mechanism with respect to the infrared reflectance metrology of MOLD thin films. This study demonstrates the potential of machine learning for predicting the thickness of multiple layered films, addressing the limitations of optical metrology.
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