Discovery of sediment indicating rapid lake-level fall in the late Pleistocene Gokarna Formation, Kathmandu Valley, Nepal: implication for terrace formation

Sediment indicating a rapid fall in lake level has been discovered in the late Pleistocene Gokarna Formation, Kathmandu Valley, Nepal. The indicator is observed along a widely traceable erosional surface in this formation, and is characterized by (1) gently inclined (ca. 10°) tabular cross-stratified sand beds of delta front origin consisting of coarser material and showing gradual decrease in elevation of its top to the progradation direction, (2) an antidune cross-laminated sand bed that interfingers with the delta front deposit, and (3) an approximately 5 m-deep erosional depression filled with convolute laminated sand beds and recognized at a location distal to that where deposits (1) and (2) were found. The early phase of rapid lake level fall caused minor erosion of the delta plain deposits by fluvial processes, introducing a higher rate of progradation of the delta front and resulting in the accumulation of deposit (1). The delta emerged as dry land due to further lowering of the lake level. The antidune cross-laminated sand bed shows evidence of having accumulated from a high-velocity stream that may have formed as the lake water drained from the delta front during the lowering of lake level. When the lake level fell below the level of the topographic high created by delta accumulation, incised valleys may have formed and part of them may have been filled with sediment at that time. The rapid fall in lake level is interpreted to have been the result of lake-wall failure, which would have occurred at the gorge outlet as the only discharge path for the basin. The initial rise of lake level causing accumulation of terrace sediments may have been due to the formation of a plug at this outlet, attributable to mass movement along the gorge

Virological characteristics of the SARS-CoV-2 Omicron BA.2.75 variant

SARS-CoV-2オミクロンBA.2.75株（通称ケンタウロス）のウイルス学的性状の解明. 京都大学プレスリリース. 2022-10-12.The SARS-CoV-2 Omicron BA.2.75 variant emerged in May 2022. BA.2.75 is a BA.2 descendant but is phylogenetically distinct from BA.5, the currently predominant BA.2 descendant. Here, we show that BA.2.75 has a greater effective reproduction number and different immunogenicity profile than BA.5. We determined the sensitivity of BA.2.75 to vaccinee and convalescent sera as well as a panel of clinically available antiviral drugs and antibodies. Antiviral drugs largely retained potency but antibody sensitivity varied depending on several key BA.2.75-specific substitutions. The BA.2.75 spike exhibited a profoundly higher affinity for its human receptor, ACE2. Additionally, the fusogenicity, growth efficiency in human alveolar epithelial cells, and intrinsic pathogenicity in hamsters of BA.2.75 were greater than those of BA.2. Our multilevel investigations suggest that BA.2.75 acquired virological properties independent of BA.5, and the potential risk of BA.2.75 to global health is greater than that of BA.5

ニホンサンBetulaノセイタイガクテキケンキュウ

京都大学0048新制・論文博士理学博士乙第925号論理博第199号新制||理||83(附属図書館)1639UT51-51-L198(主査)教授 芦田 譲治, 教授 北村 四郎, 教授 新家 浪雄, 教授 畠山 伊佐男学位規則第5条第2項該当Kyoto UniversityDA

Forest Structure, Composition, and Distribution on a Pacific Island, with Reference to Ecological Release and Speciation

Native forest and scrub of Chichijima, the largest island in the Bonins, were classified into five types based on structural features: ElaeocarpusArdisia mesic forest, 13-16 m high , dominated by Elaeocarpus photiniaefolius and Ardisia sieboldii; Pinus-Schima mesic forest, 12-16 m high , consisting of Schima mertensiana and an introduced pine , Pinus lutchuensis; RhaphiolepisLivistonia dry forest, 2-6 m high, mainly occupied by Rhaphiolepis indica v. integerrima; Distylium-Schima dry forest, 3-8 m high , dominated by Distylium lepidotum and Schima mertensiana; and Distylium-Pouteria dry scrub, 0.3-1.5 m high , mainly composed of Distylium lepidotum. A vegetation map based on this classification was developed. Species composition and structural features of each type were analyzed in terms of habitat condition and mechanisms of regeneration. A group of species such as Pouteria obovata, Syzgygium buxifolium, Hibiscus glaber, Rhaphiolepis indica v. integerrima, and Pandanus boninensis, all with different growth forms from large trees to stunted shrubs, was subdominant in all vegetation types. Schima mertensiana , an endemic pioneer tree, occurred in both secondary forests and climax forests as a dominant canopy species and may be an indication of " ecological release," a characteristic of oceanic islands with poor floras and little competitive pressure. Some taxonomic groups (Callicarpa, Symplocos, Pittosporum, etc.) have speciated in the understory of Distylium-Schima dry forest and Distylium-Pouteria dry scrub. Speciation seems to have occurred exclusively where there are comparatively small numbers of component species, historically stable habitats, some opportunity for regeneration without large-scale disturbance, and the occasional occurrence of canopy gaps