Soka University Repository / 創価大学機関リポジトリ
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Matrimonial Alliances of the Borderland Nobility in Early Modern Europe: A Quantitative Analysis Based on Genealogical Data
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On Basic Japanese Language Teaching for the Subject Learning Teaching the Auxiliary Verb “youda”
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Characterization of the phytoplankton size composition and light absorption coefficient in the temperate coastal waters of Sagami Bay
Get PDFPhytoplankton constitute the base of the aquatic food web and are the primary driver of biogeochemical processes such as the e port of carbon to the deep ocean. Knowledge of the distributions, compositions, and biomass of the phytoplankton community are essential to under stand biogeochemical cycles. Phytoplankton can be enumerated by microscopy, but this requires e tensive time for sample preparation and counting, especially if statistically valid counts of the less abundant phytoplankton classes are required. Further, smaller picoplankton can be difficult to identify since they lack ta onomically e ternal morphological features. Thus, the accessory pigment-based model has been used to estimate phytoplankton communities based on their size classes: micro- (M; > 20 µm), nano- (N; 2-20 µm) and pico-phytoplankton (P; < 2 µm). Light absorption by phytoplankton has a direct influence on the optical properties of seawater, and there is a growing effort to develop approaches to identify the spatial and temporal variability of the phytoplankton community from satellites. However, estimating the phytoplankton com munity in optically comple coastal waters from satellites is still a challenging problem because phytoplankton are only one of multiple optically significant constituents of seawater. Also, there are limitations of wavelength that satellites can measure, and overlapping signature pigment of each phytoplankton community. In order to improve the estimation of phytoplankton communi ties, it is necessary to understand the light absorption coefficient of phytoplankton, aph (,,) asso ciated with the varying community structure. The objective of this study was to characterize the variability of phytoplankton size classes and their light absorption coefficients in the temperate coastal waters of Sagami Bay. The specific objectives were (1) to classify phytoplankton com munities based on cell size, (2) to investigate co-variability of aph (,,) spectra according to the classification. The present study conducted in situ observations from April 2016 to September 2022 at Station M (St. M: 35° 09’ 45” N, 139° 10’00” E) in the temporal coastal waters of Sagami Bay, Japan. Water samples for pigments and light absorption properties of phytoplankton were collected from surface water with a bucket, and measured by high-performance liquid chroma tography and spectrophotometry, respectively. Phytoplankton size class composition was esti mated based on pigment concentrations. The results showed that the three groups (Group M, N, P) generated according to the phytoplankton size composition were significantly different (R = 0.646, p < 0.001). Also, the most dominant group throughout the study period was microplank ton (n = 110). The aph (,,) spectra showed peaks around 438 nm and 465 nm in the blue band and 674 nm in the red band. Using three wavelengths peaks, although the aph (,,) of group M was sig nificantly higher than that of group N, Group P was not significantly different from other groups. This study suggests that the aph (,,) spectrum in the temperate coastal waters of Sagami Bay is significantly co-varying with the variability of phytoplankton size composition. The results sug gest that analyzing the difference in aph (,,) spectra ratios and performing derivative analysis, coupled with analysis of phytoplankton size distribution and pigment composition should im prove our ability to characterize phytoplankton spatio-temporal distribution from space.departmental bulletin pape
Surface nutrient regime and bottom hypoxia in Manila Bay during the southwest monsoon
Get PDFWe e amined the surface nutrient regime and hypo ia in Manila Bay, Philippines, during the southwest monsoon along a transect from off Limay, Bataan Peninsula, to Metro Ma nila. The water column showed stratification, with warm, less saline water in the top 10 meters overlying cold, saline bottom water. Hypo ia was present in the bottom waters along the entire transect, and ano ic conditions were observed off Manila. Ammonium concentrations ranged from 6.7 to 40.2 µM, e ceeding those of nitrate and nitrite, both of which were nearly depleted at almost all stations e cept off-Manila, with levels below 0.1 µM. Phosphate varied from 0.1 to 1.9 µM, resulting in a stoichiometrically nitrogen-rich condition at the surface, with N:P ratios ranging from 17.1 to 149.7 and an average of 37.4. This is in contrast to the phosphate-rich con ditions reported during the northeast monsoon period. A plume with high nutrient concentrations and high chlorophyll a was observed off Manila, indicating freshwater inflow from sewage and the Pasig River. Diatoms, including the Skeletonema costatum comple and Chaetoceros spp., were abundant, and these eutrophic conditions likely favored the occurrence of green Noctiluca, while it was not observed during our study.departmental bulletin pape
Higher Education for Refugees: As a Priority for Complementary Protections
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Reprint of Precedents of Various Feudal Lords（ Daimyo 大名）〔Shokereiso 諸家例叢〕 Transcribed by Goro Ebata（ 江幡五郞）: Two-Volume Books（ 14）
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Chain RMA and Japan’s Security Policy
Get PDFJapan should maintain the three non-nuclear principles and defend itself exclusively.
Japan seems to have abandoned the special defense of Missile Defense system and adopted deterrent defense with retaliation as the main axis and enemy attack as the main body, but China and Russia have already started Hybridization war and Unrestricted warfare. There is no need to worry about whether Japan can be protected by strengthening the security of its original military forces?departmental bulletin pape