Search Results (33)

Integrated hydrological modeling plays a crucial role in advancing sustainable water resource management, particularly in regions facing seasonal and extreme precipitation events. However, comprehensive studies that assess hydrological variability in temperate river basins remain limited. This study addresses this gap by evaluating the performance of the Soil and Water Assessment Tool (SWAT) in simulating streamflow, water balance, and seasonal hydrological dynamics in the Chikugo River Basin, Kyushu Island, Japan. The basin, originating from Mount Aso and draining into the Ariake Sea, is subject to frequent typhoons and intense rainfall, making it a critical case for sustainable water governance. Using the Sequential Uncertainty Fitting Version 2 (SUFI-2) approach, we calibrated the SWAT model over the period 2007–2021. Water balance analysis revealed that baseflow plays dominant roles in basin hydrology which is essential for agricultural and domestic water needs by providing a stable groundwater contribution despite increasing precipitation and varying water demand. These findings contribute to a deeper understanding of hydrological behavior in temperate catchments and offer a scientific foundation for sustainable water allocation, planning, and climate resilience strategies. Full article

Caryopteris incana (Thunb. ex Houtt.) Miq., an endangered species native to western Kyushu, Japan, forms locally isolated populations. In our previous studies, we conducted a distribution survey of 109 populations across four regions and performed phylogenetic analyses using chloroplast DNA to clarify their genetic structure and diversity. The primary objective of this study was to clearly compare and evaluate phenotypic differences that are considered to be genetically fixed among adaptive traits evolved in response to the native environments of each region. We evaluated morphological characteristics—such as floral parts, leaves, and plant form—under uniform cultivation conditions using seeds collected from native populations. As a result, region-specific phenotypes were identified, and diverse variations were observed both among and within regions. Furthermore, the presence of phenotypes with high coefficients of variation even within the same region suggests the existence of diverse gene pools suitable for various applications. This study not only contributes to understanding the regional adaptive strategies of C. incana, but also provides fundamental data for developing conservation plans for this endangered species. Additionally, the phenotypic information obtained is expected to be useful for breeding horticultural varieties and for setting future conservation priorities. Full article

This study focuses on typical regions of strong ageostrophic processes in the Kuroshio using high-resolution remote sensing satellite reanalysis data and Argo float data. By analyzing the relationship between the Rossby number and chlorophyll concentration from June to August in the summer of 2020, the spatial characteristics of ageostrophic processes and their impact on the phytoplankton community distribution are explored. The results indicate that ageostrophic processes, driven by coastal topography, are stably generated in the regions of the Bashi Channel, northeastern Taiwan waters, southwestern Kyushu Island, and southern Shikoku Island. Furthermore, the intensity of these ageostrophic processes shows an overall positive correlation with chlorophyll concentration. The local mixing and subfront circulations induced by ageostrophic processes pump deep nutrients into the euphotic zone, supporting the growth and reproduction of phytoplankton, which leads to the formation of significant chlorophyll hotspots in regions controlled by ageostrophic processes. Full article

Background: Since there are many differential diagnoses for cemento-osseous dysplasia (COD), it is very difficult for dentists to avoid misdiagnosis. In particular, if COD is related to an embedded tooth, differential diagnosis is difficult. However, there have been no reports on the characteristics of the imaging findings of COD associated with embedded teeth. The aim of the present study was to investigate the occurrence and imaging characteristics of cemento-osseous dysplasia (COD) associated with embedded teeth, in order to appropriately diagnose COD with embedded teeth. Methods: The radiographs with or without histological findings of 225 patients with COD were retrospectively analyzed. A retrospective search through the picture archiving and communication system (PACS) of the Division of Oral and Maxillofacial Radiology of Kyushu Dental University Hospital was performed to identify patients with COD between 2011 and 2022. Results: Fifteen COD-associated embedded mandibular third molars were identified in 13 patients. All 13 patients were asymptomatic. On imaging, COD associated with embedded mandibular third molars appeared as masses that included calcifications around the apex of the tooth. On panoramic tomography, COD showed inconspicuous internal calcification similar to that of odontogenic cysts or simple bone cysts, especially in patients with COD only around the mandibular third molar region. Those with prominent calcification resembled cemento-ossifying fibroma, calcifying epithelial odontogenic tumor, calcifying odontogenic cyst, adenomatoid odontogenic tumor, and so on, as categories of masses that include calcifications on panoramic tomography and computed tomography. Conclusions: The current investigation is the first to report and analyze the imaging characteristics of COD associated with embedded teeth. It is important to consider the differences between COD and other cystic lesions on panoramic tomography, and the differences between COD and masses that include calcifications on CT. Full article

This study aimed to clarify the vegetation history of planted forests that are still in use today by comparing the types of land afforested in 1960 with the post-war afforestation period in Japan’s Hokkaido, Kyushu, and Kinki regions. It was during that time that the majority of the planted forest in these regions was established. We calculated the afforestation ratios (afforested area of each type of land/total afforested area) for the smallest survey unit, the 1950 administrative sections, using data from the 1960 World Agriculture and Forestry Census on the afforested areas of various types of land (i.e., deforested areas resulting from natural forests, deforested areas resulting from planted forests, and areas other than forests). The afforestation ratios were then sorted into ten categories for each municipality in the three regions and mapped using GIS. The analysis results showed that the vegetation history in Kyushu, even within the same municipality, was frequently mixed in 1960; in Hokkaido, the afforestation ratio for deforested areas resulting from natural forests was extremely high, while the afforestation ratio for deforested areas resulting from planted forests was low. In contrast, the Kinki region has a low afforestation ratio for non-forest regions. This study provides useful information for ecosystem management. Full article

On 5–6 July 2017, an unstable atmospheric condition caused an unusual concentration of rainfall above the Northern part of Kyushu Island, triggering a set of hydro-meteorological hazards. Within the affected area, the mountainous subwatershed of the Akatani River was significantly impacted by numerous landslides combined with debris flow and floods. National and local agencies deployed a plan of reconstruction to restore the floodplain and protect inhabitants. Regarding the hydrosystem in the Akatani watershed, this reconstruction project mainly focuses on the restoration of damaged protection systems and the construction of new infrastructures. Thus, this paper aims to explain the restoration plan of the Akatani River in terms of the strategic Japanese River System Sabo and then as a model of a national-scale spatial plan. It draws on (i) a literature review based on the historical evolution of Japanese protection systems and the River Sabo System; (ii) field surveys in 2019, 2022 and 2023, in conjunction with (iii) interviews with local, regional, and national officials; and (iv) a Geographical Information System analysis of previously and newly built protection systems through aerial photograph interpretation and geospatial data. Sabo works implemented in the Akatani watershed illustrate the engineering vision of Japanese river management. They also constitute a comprehensive system and include a downstream–upstream logic which echoes that of the River System Sabo. In addition, the disaster of July 2017 and the government’s response emphasize the continuous adaptation and improvement of the Japanese disaster management system, which mitigates severe disasters. Full article

Accurate forest information on tree species, stand age, tree density, and stand volume is required to ensure effective forest management practices. In Japan, forest information is consolidated in forest yield tables and stand density management diagrams (SDMDs) that are specifically designed for major forest plantation species. In this study, we analyzed whether the current full density curve in the SDMD of Hinoki (Chamaecyparis obtusa) plantation stands in Kyushu Island aligns with the characteristics of the existing stands. Data from 18 Hinoki forests were used to measure tree heights, diameters, and densities. Equations were developed to establish relationships between stand factors, and various curves were derived for average height, competition ratio, full density, yield ratio, average diameter, and natural mortality. The results showed that the current full density curve in the SDMD for Hinoki plantation stands did not completely align with the characteristics of the existing Hinoki plantation stands in Kyushu Island. Thus, the full density curve in the SDMD for the Hinoki stands in this region should be significantly adjusted. These results can enhance forest management in Japan and advance SDMD modeling and its application in forest planning and management. Full article

This paper discusses the relationship between the vertical ground motion and ionospheric disturbances before the Kumamoto earthquake on 16 April 2016, in Kyushu, Japan, using the vertical ground motion measured by slant gauges widely distributed in Kyushu, and the NmF2 observed by ionosondes in Japan and another region. We provide evidence that vertical ground motion excites internal gravity waves (IGWs) that disturb changes in the ionospheric plasma density. From the spectral analysis results of the vertical ground motion data, the summation of various period (frequency) components analyzed from the original data of the slant gauge shows a possible correlation with the change of NmF2 before the earthquake. On the other hand, the influence of the geomagnetic disturbance on vertical ground motion seems to exist. However, we cannot confirm that vertical ground motion is influenced by the geomagnetic disturbance (Kp index) and that the earthquake is triggered by the geomagnetic disturbance. There are two conditions for the vertical ground motion to disturb variations in the ionospheric plasma density: (1) The effective vertical ground motion period should be shorter than 5 h. In addition, (2) vertical ground motion should continue to exist so that wave energy can be continuously injected into the atmosphere. A possible mechanism with which to modify the ionosphere is discussed. The results of this study can provide a basis for the future ionospheric precursors of earthquakes by using the vertical ground motion. Full article

Bacterial wilt is a soil-borne disease that causes severe damage in ginger-growing regions of Japan (eight prefectures in the Shikoku, Kyushu, and Honshu regions). Because the pathogen Ralstonia pseudosolanacearum usually lives in deeper soil and infects host plants via the roots, it is not easy to eliminate even with chemical pesticides (such as soil fumigants). In our previous study, we found that anaerobic soil disinfestation with diluted ethanol (Et-ASD) effectively eliminated this pathogen. We conducted field experiments to confirm the effectiveness of Et-ASD in a ginger monoculture system. Eight trials were conducted in seven different ginger fields from spring to autumn. Excluding one trial in early spring, seven trials in summer successfully eliminated the pathogen from the field soil (below the detection limit by the developed sensitive bio-PCR method), and no disease recurrence was observed after ASD treatment. In addition, other useful methods for controlling the disease were explored, including proper field management after the disease outbreak and the disinfection of seed rhizomes. Based on these results, a comprehensive control system for bacterial wilt disease in ginger was developed. Full article

Extreme rainfall causes floods and landslides, and so damages humans and socioeconomics; for instance, floods and landslides have been triggered by repeated torrential precipitation and have caused severe damage in the Kyushu region, Japan. Therefore, evaluating extreme rainfall in Kyushu is necessary to provide basic information for measures of rainfall-induced disasters. In this study, we estimated the probability of daily rainfall in Kyushu. The annual maximum values for daily rainfall at 23 long-record stations were normalized using return values at each station, corresponding to 2 and 10 years, and were combined by the station-year method. Additionally, the return period (RP) was calculated by fitting them to the generalized extreme value distribution. Based on the relationship between the normalized values of annual maximum daily rainfall and the RP, we obtained a regression equation to accurately estimate the RP up to 300 years by using data at given stations, considering outliers. In addition, we verified this equation using data from short-record stations where extreme rainfall events triggering floods and landslides were observed, and thereby elucidated that our method was consistent with previous techniques. Thus, this study develops strategies of measures for floods and landslides. Full article

Focusing on the components of fine particulate matter, i.e., PM_2.5, we have analyzed the factors that led to the high concentrations of each chemical component in PM_2.5 during our observations in Fukuoka, Japan in spring 2020. The backward trajectory showed that air masses reached Fukuoka via the Yellow Sea and the southern part of South Korea when PM_2.5 and each chemical component were high in concentrations. On the other hand, diurnal variations in ozone were also observed, suggesting that both transboundary and local air pollution are involved. Air masses reached the southern part of the Kyushu region when only sulfate concentrations were high. A volcano eruption led the high sulfate concentration. When only polycyclic aromatic hydrocarbons (PAHs) concentrations were high, air masses often reached the northern part of Kyushu, indicating that there may be a specific local source for PAHs. Full article

To clarify the genetic diversity of the porcine reproductive and respiratory syndrome virus (PRRSV) in Japan in recent years, we determined the nucleotide sequence of open reading frame 5 of 2482 PRRSV sequences obtained from samples collected from pigs between January 2018 and December 2020. As a result of molecular phylogenetic analysis, Cluster II represented the largest proportion (44.9–50.6%) throughout the study period, followed by Cluster IV (34.0–40.8%), Cluster III (7.8–12.1%), Cluster I (3.1–6.7%), and Cluster V (0.1–0.2%). The relative distributions between Clusters varied between geographic regions and between years: in 2018, Cluster II was the most prevalent in all regions. In 2019, Cluster II was dominant in the Hokkaido and Tohoku regions, while in other regions Cluster IV was dominant. In 2020, Cluster IV was dominant in the Kanto/Tosan and Kyushu/Okinawa regions, whilst in other regions Cluster II was predominant. Compared with a previous study, the proportions of genome sequences classified in Clusters II and IV significantly increased (p = 0.042 and 0.018, respectively) and those classified in Cluster III significantly decreased (p < 0.01). The widespread use of live attenuated vaccines using strains that belong to Cluster II might have accounted for these changes in the relative distribution between Clusters. Full article

Ingesting fish contaminated with ciguatoxins (CTXs) originating from epibenthic dinoflagellates causes ciguatera fish poisoning (CFP). CFP occurs mainly in the tropical and subtropical Indo–Pacific region and the Caribbean Sea. Furthermore, it occurs sporadically in Japan, especially in the Ryukyu Islands between Taiwan and Kyushu, Japan. Variola louti is the most frequently implicated fish with a suggested toxin profile, consisting of ciguatoxin-1B and two deoxy congeners. Therefore, using the liquid chromatography–tandem mass spectrometry (LC-MS/MS), we analyzed CTXs in the flesh of 154 individuals from various locations and detected CTXs in 99 specimens (64%). In 65 fish (43%), CTX levels exceeded the Food and Drug Administration (FDA) guidance level (0.01 µg/kg). Furthermore, in four specimens (3%), the guideline level in Japan (>0.18 µg/kg) was met. Additionally, although the highest total CTX level was 0.376 µg/kg, the consumption of 180 g of this specimen was assumed to cause CFP. Moreover, only CTX1B, 52-epi-54-deoxyCTX1B, and 54-deoxyCTX1B were detected, with the relative contribution of the three CTX1B analogs to the total toxin content (35 ± 7.7 (SD)%, 27 ± 8.1%, and 38 ± 5.6%, respectively) being similar to those reported in this region in a decade ago. Subsequently, the consistency of the toxin profile in V. louti was confirmed using many specimens from a wide area. As observed, total CTX levels were correlated with fish sizes, including standard length (r = 0.503, p = 3.08 × 10⁻¹¹), body weight (r = 0.503, p = 3.01 × 10⁻¹¹), and estimated age (r = 0.439, p = 3.81 × 10⁻⁷) of the specimens. Besides, although no correlation was observed between condition factor (CF) and total CTX levels, a significance difference was observed (p = 0.039) between the groups of skinnier and fattier fish, separated by the median CF (3.04). Results also showed that the CF of four specimens with the highest CTX level (>0.18 µg/kg) ranged between 2.49 and 2.87, and they were skinnier than the average (3.03) and median of all specimens. Full article

Remote sensing is an effective method of evaluating building damage after a large-scale natural disaster, such as an earthquake or a typhoon. In recent years, with the development of computer vision technology, deep learning algorithms have been used for damage assessment from aerial images. In April 2016, a series of earthquakes hit the Kyushu region, Japan, and caused severe damage in the Kumamoto and Oita Prefectures. Numerous buildings collapsed because of the strong and continuous shaking. In this study, a deep learning model called Mask R-CNN was modified to extract residential buildings and estimate their damage levels from post-event aerial images. Our Mask R-CNN model employs an improved feature pyramid network and online hard example mining. Furthermore, a non-maximum suppression algorithm across multiple classes was also applied to improve prediction. The aerial images captured on 29 April 2016 (two weeks after the main shock) in Mashiki Town, Kumamoto Prefecture, were used as the training and test sets. Compared with the field survey results, our model achieved approximately 95% accuracy for building extraction and over 92% accuracy for the detection of severely damaged buildings. The overall classification accuracy for the four damage classes was approximately 88%, demonstrating acceptable performance. Full article

The method of automatically controlling the CO₂ concentration in a greenhouse depending on ventilation was examined in order to efficiently improve the productivity of strawberries under the weather conditions in the northern part of Kyushu in Japan. The effects of CO₂ enrichment on the yields, fruit Brix, and economic value of the strawberry ‘Sagahonoka’ were investigated. In addition, in order to clarify the physiological response of ‘Sagahonoka’ to the CO₂ concentration, the photosynthetic rate, translocation, and photoassimilate distribution rate were measured. It was found that maintaining the CO₂ concentrations above 800 μmol mol⁻¹ and 400 μmol mol⁻¹ during no ventilation and ventilation, respectively, resulted in 25% increases in marketable fruit yields and a 0.2–1.2% higher fruit Brix compared to control, which was kept in 400 μmol mol⁻¹ CO₂ or above all day regardless of ventilation. Additionally, the economic value of ‘Sagahonoka’ was increased. The photosynthetic rate of ‘Sagahonoka’ increased linearly up to 800 μmol mol⁻¹ CO₂, and high CO₂ concentrations affected the distribution for the primary fruit, the most significant sink. It was clarified that CO₂ enrichment at 800 μmol mol⁻¹ for ‘Sagahonoka’ was effective in increasing the photosynthetic rate and distribution of photoassimilates to fruits, and the yields of strawberries could be increased efficiently by automatically controlling the CO₂ concentration depending on ventilation in a southern region of Japan. Full article