Magnetic and transport properties due to non-coplanar spin structure in frustrated antiferromagnets

学位の種別: 課程博士審査委員会委員 : (主査)東京大学准教授 中辻 知, 東京大学教授 大谷 義近, 東京大学教授 辛 埴, 東京大学教授 竹谷 純一, (独)理化学研究所チームリーダー 有田 亮太郎University of Tokyo(東京大学

Switching to Dupilumab from Other Biologics without a Treatment Interval in Patients with Severe Asthma: A Multi-Center Retrospective Study

Background: Dupilumab is a fully humanized monoclonal antibody that blocks interleukin4 and interleukin-13 signals. Several large clinical trials have demonstrated the efficacy of dupilumab in patients with severe asthma. However, few studies have examined a switch to dupilumab from other biologics. Methods: This retrospective, multi-center observational study was conducted by the Okayama Respiratory Disease Study Group. Consecutive patients with severe asthma who were switched to dupilumab from other biologics without a treatment interval between May 2019 and September 2021 were enrolled. Patients with a treatment interval of more than twice the standard dosing interval for the previous biologic prior to dupilumab administration were excluded. Results: The median patient age of the 27 patients enrolled in this study was 57 years (IQR, 45-68 years). Eosinophilic chronic rhinosinusitis (ECRS)/chronic rhinosinusitis with nasal polyp (CRSwNP) was confirmed in 23 patients. Previous biologics consisted of omalizumab (n = 3), mepolizumab (n = 3), and benralizumab (n = 21). Dupilumab significantly improved FEV1 (median improvement: +145 mL) and the asthma control test score (median improvement: +2). The overall response rate in patients receiving dupilumab for asthma as determined using the Global Evaluations of Treatment Effectiveness (GETE) was 77.8%. There were no significant differences in the baseline characteristics of the GETE-improved group vs. the non-GETE-improved group. ECRS/CRSwNP improved in 20 of the 23 patients (87.0%). Overall, 8 of the 27 patients (29.6%) developed transient hypereosinophilia (>1500/ mu L), but all were asymptomatic and able to continue dupilumab therapy. Conclusions: Dupilumab was highly effective for the treatment of severe asthma and ECRS/CRSwNP, even in patients switched from other biologics without a treatment interval

Large magneto-optical Kerr effect and imaging of magnetic octupole domains in an antiferromagnetic metal

When a polarized light beam is incident upon the surface of a magnetic material, the reflected light undergoes a polarization rotation. This magneto-optical Kerr effect (MOKE) has been intensively studied in a variety of ferro- and ferrimagnetic materials because it provides a powerful probe for electronic and magnetic properties as well as for various applications including magneto-optical recording. Recently, there has been a surge of interest in antiferromagnets (AFMs) as prospective spintronic materials for high-density and ultrafast memory devices, owing to their vanishingly small stray field and orders of magnitude faster spin dynamics compared to their ferromagnetic counterparts. In fact, the MOKE has proven useful for the study and application of the antiferromagnetic (AF) state. Although limited to insulators, certain types of AFMs are known to exhibit a large MOKE, as they are weak ferromagnets due to canting of the otherwise collinear spin structure. Here we report the first observation of a large MOKE signal in an AF metal at room temperature. In particular, we find that despite a vanishingly small magnetization of $M \sim$0.002 $\mu_{\rm B}$/Mn, the non-collinear AF metal Mn$_3$Sn exhibits a large zero-field MOKE with a polar Kerr rotation angle of 20 milli-degrees, comparable to ferromagnetic metals. Our first-principles calculations have clarified that ferroic ordering of magnetic octupoles in the non-collinear Neel state may cause a large MOKE even in its fully compensated AF state without spin magnetization. This large MOKE further allows imaging of the magnetic octupole domains and their reversal induced by magnetic field. The observation of a large MOKE in an AF metal should open new avenues for the study of domain dynamics as well as spintronics using AFMs.Comment: 30 pages, 4 figure

Host selection of hematophagous leeches (Haemadipsa japonica): Implications for iDNA studies

The development of an efficient and cost‐effective method for monitoring animal populations or biodiversity is urgently needed, and invertebrate‐derived DNA (iDNA) may offer a promising tool for assessing the diversity and other ecological information of vertebrates. We studied the host species of a hematophagous leech (Haemadipsa japonica) in Yakushima by genetic barcoding and compared the results with those for mammal composition revealed by camera trapping. We analyzed 119 samples using two sets of primers by Sanger sequencing and one set of primer by next generation sequencing. The proportion of the samples that were successfully sequenced and identified to at least one species was 11.8–24.3%, depending on the three different methods. In all of these three methods, most of the samples were identified as sika deer (18/20, 6/15 and 16/29) or human (2/20, 7/15 and 21/29). The nonhuman mammal host species composition was significantly different from that estimated by camera trapping. Sika deer was the main host, which may be related with their high abundance, large body size and terrestriality. Ten samples included DNA derived from multiple species of vertebrates. This may be due to the contamination of human DNA, but we also found DNA from deer, Japanese macaque and a frog in the same samples, suggesting the mixture of the two meals in the gut of the leech. Using H. japonica‐derived iDNA would not be suitable to make an inventory of species, but it may be useful to collect genetic information on the targeted species, due to their high host selectivity