36 research outputs found
Study of laser frequency stability from the observed vertical wind velocity by the Na lidar at Troms*
The Tenth Symposium on Polar Science/Ordinary sessions: [OS] Space and upper atmospheric sciences, Wed. 4 Dec. /Entrance Hall (1st floor) at National Institute of Polar Research (NIPR
Study on variation of neutral temperature in the polar MLT region using a sodium LIDAR at Tromsø
第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日(月) 国立極地研究所 2階大会議
A statistical study of convective and dynamic instabilities in the polar upper mesosphere above Tromsø
We have studied the convective (or static) and dynamic instabilities between 80 and 100 km above Tromsø (69.6° N,
19.2° E) using temperature and wind data of 6 min and 1 km resolutions primarily almost over a solar cycle obtained
with the sodium lidar at Tromsø. First, we have calculated Brunt–Väisälä frequency (N) for 339 nights obtained from
October 2010 to December 2019, and the Richardson number (Ri) for 210 nights obtained between October 2012 to
December 2019. Second, using those values (N and Ri), we have calculated probabilities of the convective instability
(N2<0) and the dynamic instability (0≤Ri<0.25) that can be used for proxies for evaluating the atmospheric stability. The probability of the convective instability varies from about 1% to 24% with a mean value of 9%, and that of
the dynamic instability varies from 4 to 20% with a mean value of 10%. Third, we have compared these probabilities
with the F10.7 index and local K-index. The probability of the convective instability shows a dependence (its correlation coefcient of 0.45) of the geomagnetic activity (local K-index) between 94 and 100 km, suggesting an auroral
infuence on the atmospheric stability. The probability of the dynamic instability shows a solar cycle dependence (its
correlation coefcient being 0.54). The probability of the dynamic instability shows the dependence of the 12 h wave
amplitude (meridional and zonal wind components) (C.C.=0.52). The averaged potential energy of gravity waves
shows decrease with height between 81 and 89 km, suggesting that dissipation of gravity waves plays an important
role (at least partly) in causing the convective instability below 89 km. The probability of the convective instability
at Tromsø appears to be higher than that at middle/low latitudes, while the probability of the dynamic instability is
similar to that at middle/low latitudes
The earliest thymic T cell progenitors sustain B cell and myeloid lineage potential
The stepwise commitment from hematopoietic stem cells in the bone marrow to T lymphocyte-restricted progenitors in the thymus represents a paradigm for understanding the requirement for distinct extrinsic cues during different stages of lineage restriction from multipotent to lineage-restricted progenitors. However, the commitment stage at which progenitors migrate from the bone marrow to the thymus remains unclear. Here we provide functional and molecular evidence at the single-cell level that the earliest progenitors in the neonatal thymus had combined granulocyte-monocyte, T lymphocyte and B lymphocyte lineage potential but not megakaryocyte-erythroid lineage potential. These potentials were identical to those of candidate thymus-seeding progenitors in the bone marrow, which were closely related at the molecular level. Our findings establish the distinct lineage-restriction stage at which the T cell lineage-commitment process transits from the bone marrow to the remote thymus. © 2012 Nature America, Inc. All rights reserved
Study on upward propagating AGWs in the polar MLT region using sodium LIDAR and meteor radar data
第2回極域科学シンポジウム/第35回極域宙空圏シンポジウム 11月14日(月) 国立極地研究所 2階大会議
北極域上部中間圏・下部熱圏における鉛直運動
第6回極域科学シンポジウム分野横断型セッション:[IM] 横断 中層大気・熱圏11月17日(火) 統計数理研究所 セミナー室2(D304
A case study on identification of blocking mechanism for upward propagating gravity wave in polar MLT region
第3回極域科学シンポジウム 横断セッション「中層大気・熱圏」 11月26日(月) 国立極地研究所 2階大会議
Initial seeding of the embryonic thymus by immune-restricted lympho-myeloid progenitors
The final stages of restriction to the T cell lineage occur in the thymus after the entry of thymus-seeding progenitors (TSPs). The identity and lineage potential of TSPs remains unclear. Because the first embryonic TSPs enter a non-vascularized thymic rudiment, we were able to directly image and establish the functional and molecular properties of embryonic thymopoiesis-initiating progenitors (T-IPs) before their entry into the thymus and activation of Notch signaling. T-IPs did not include multipotent stem cells or molecular evidence of T cell-restricted progenitors. Instead, single-cell molecular and functional analysis demonstrated that most fetal T-IPs expressed genes of and had the potential to develop into lymphoid as well as myeloid components of the immune system. Moreover, studies of embryos deficient in the transcriptional regulator RBPJ demonstrated that canonical Notch signaling was not involved in pre-thymic restriction to the T cell lineage or the migration of T-IPs