Although solar activity may significantly impact the global environment and socioeconomic systems, the mechanisms for solar eruptions and the subsequent processes have not yet been fully understood. ...Thus, modern society supported by advanced information systems is at risk from severe space weather disturbances. Project for solar–terrestrial environment prediction (PSTEP) was launched to improve this situation through synergy between basic science research and operational forecast. The PSTEP is a nationwide research collaboration in Japan and was conducted from April 2015 to March 2020, supported by a Grant-in-Aid for Scientific Research on Innovative Areas from the Ministry of Education, Culture, Sports, Science and Technology of Japan. By this project, we sought to answer the fundamental questions concerning the solar–terrestrial environment and aimed to build a next-generation space weather forecast system to prepare for severe space weather disasters. The PSTEP consists of four research groups and proposal-based research units. It has made a significant progress in space weather research and operational forecasts, publishing over 500 refereed journal papers and organizing four international symposiums, various workshops and seminars, and summer school for graduate students at Rikubetsu in 2017. This paper is a summary report of the PSTEP and describes the major research achievements it produced.
Solar activity has been recorded as auroras or sunspots in various historical sources. These records are of great importance for investigating both long-term solar activities and extremely intense ...solar flares. According to previous studies, they were recorded as “vapor,” “cloud,” or “light,” especially in oriental historical sources; however, this terminology has not been discussed adequately, and remains still quite vague. In this paper, we suggest the possibility of using “unusual rainbow” and “white rainbow” as candidates of historical auroras in oriental historical sources, and examine if this is probable. This discovery will help us to make more comprehensive historical auroral catalogues, and require us to add these terms to auroral candidates in oriental historical sources.
Status of the AMS system at Yamagata University Moriya, Toru; Takeyama, Mirei; Sakurai, Hirohisa ...
Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms,
01/2019, Letnik:
439
Journal Article
Recenzirano
An accelerator mass spectrometry (AMS) system and an automated graphitization line were installed at Yamagata University (YU) in 2009. Approximately 2000 samples are measured per year using the ...YU-AMS system. The long-term stability of the system was assessed by measuring the standard sample IAEA-C7 graphitized by the automated graphitization line. In March 2014, a second automated graphitization line and an additional ion source for the YU-AMS system were installed to meet the requirement of 14C measurement for pharmacological and medical applications. A phosphoric acid treatment system was also developed for the radiocarbon dating of calcium carbonate (CaCO3) in shell and coral samples. Performance tests on the new YU-AMS system were carried out by measuring the C-series standard samples (C1-C9) and oxalic acid II (HOxII) obtained from IAEA and NIST, respectively. The results of the 14C concentration pMC are in good agreement with the consensus values. Performance tests for medical applications were also carried out by measuring the 14C concentration of 14C-glucose in human plasma.
A signal of the 27-day solar rotational period is often observed in cloud and lightning activities over the globe. Here we provide evidence of the 27-day periodicity of lightning activity in Japan ...using daily observational records of lightning for AD 1989–2015. The 27-day period is detected with 4.2 standard deviations, but only in wide-area lightning activity covering more than a 105 km2. The 27-day signal is more prominent around the maxima of solar decadal cycles.
The El Niño–Southern Oscillation (ENSO) appears to strongly influence East Asian Summer Monsoon (EASM) rainfall, but the relatively short instrumental rainfall record hinders the development of a ...longer-term understanding of this teleconnection. To partially overcome this issue, here we reconstruct precipitation from tree-ring oxygen isotopes (δ18O) in central Japan during AD 1612–1935. Our results indicate that tree-ring cellulose δ18O is significantly correlated with May–June (MJ) precipitation, allowing us to investigate the link between the EASM summer rainfall and ENSO over the past 400 years. Time- and frequency-domain comparison of the tree-ring δ18O record and recent ENSO reconstructions reveal a common high-frequency (3–8 year) variability that characterized the mid-17th, late 18th and late 19th centuries. Similar analyses of instrumental MJ precipitation and several ENSO indexes during the 20th century indicate that this high-frequency oscillation reappeared from AD 1980. Comparison of ENSO and Pacific Decadal Oscillation (PDO) indexes indicates that the ENSO–EASM teleconnection is strong when ENSO variance is high, and the PDO phase may modulate the ENSO–EASM relationship over the past 400 years.
Thunderstorm and cloud activities sometimes show a 27-day period, and this has long been studied to uncover a possible important link
to solar rotation. Because the 27-day variations in the solar ...forcing parameters such as solar ultraviolet and galactic cosmic rays
become more prominent when the solar activity is high, it is expected that the signal of the 27-day period in meteorological
phenomena may wax and wane according to the changes in the solar activity level. In this study, we examine in detail the intensity
variations in the signal of the 27-day solar rotational period in thunder and lightning activity from the 18th to the 19th centuries
based on 150-year-long records found in old diaries kept in Japan and discuss their relation with the solar activity levels. Such
long records enable us to examine the signals of solar rotation at both high and low solar activity levels. We found that the signal
of the solar rotational period in the thunder and lightning activity increases as the solar activity increases. In this study, we
also discuss the possibility of the impact of the long-term climatological conditions on the signals of the 27-day period in
thunder/lightning activities. Keywords. Meteorology and atmospheric dynamics (lightning)
Encounters with nebulae, such as supernova remnants and dark clouds in the galaxy, can lead to an environmental catastrophe on the Earth through the negative climate forcings and destruction of the ...ozone layer by enhanced fluxes of cosmic rays and cosmic dust particles. A resultant reduction in primary productivity leads to mass extinctions through depletion of oxygen and food starvations as well as anoxia in the ocean. The model shows three levels of hierarchical time variations caused by supernova encounters (1–10kyrs), dark cloud encounters (0.1–10Myrs), and starbursts (~100Myrs), respectively. This “Nebula Winter” model can explain the catastrophic phenomena such as snowball Earth events, repeated mass extinctions, and Cambrian explosion of biodiversities which took place in the late Proterozoic era through the Cambrian period. The Late Neoproterozoic snowball Earth event covers a time range of ca. 200Myrs long spanning from 770Ma to the end of Cambrian period (488Ma) with two snowball states called Sturtian and Marinoan events. Mass extinctions occurred at least eight times in this period, synchronized with large fluctuations in δ13C of carbonates in the sediment. Each event is likely to correspond to each nebula encounter. In other words, the late Neoproterozoic snowball Earth and Cambrian explosion are possibly driven by a starburst, which took place around 0.6Ga in the Milky Way Galaxy. The evidences for a Nebula Winter can be obtained from geological records in sediment in the deep oceans at those times.
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•Nebula encounter leads to an environmental catastrophe: Nebula Winter.•Supernova remnant (1–10kyrs), dark cloud (0.1–10Myrs), and starbursts (~100Myrs)•Unified view to explore the late Neoproterozoic and Cambrian periods•Evidences can be obtained in sediment in the deep oceans at those times.
The Maunder Minimum (A.D. 1645–1715) is a useful period to investigate possible sun—climate linkages as sunspots became exceedingly rare and the characteristics of solar cycles were different from ...those of today. Here, we report annual variations in the oxygen isotopic composition (δ¹⁸O) of tree-ring cellulose in central Japan during the Maunder Minimum. We were able to explore possible sun—climate connections through high-temporal resolution solar activity (radiocarbon contents; Δ¹⁴C) and climate (δ¹⁸O) isotope records derived from annual tree rings. The tree-ring δ¹⁸O record in Japan shows distinct negative δ¹⁸O spikes (wetter rainy seasons) coinciding with rapid cooling in Greenland and with decreases in Northern Hemisphere mean temperature at around minima of decadal solar cycles. We have determined that the climate signals in all three records strongly correlate with changes in the polarity of solar dipole magnetic field, suggesting a causal link to galactic cosmic rays (GCRs). These findings are further supported by a comparison between the interannual patterns of tree-ring δ¹⁸O record and the GCR flux reconstructed by an ice-core ¹⁰Be record. Therefore, the variation of GCR flux associated with the multidecadal cycles of solar magnetic field seem to be causally related to the significant and widespread climate changes at least during the Maunder Minimum.
Scope
Fish oil‐derived long‐chain monounsaturated fatty acids (LCMUFA) containing chain lengths longer than 18 were previously shown to improve cardiovascular disease risk factors in mice. However, ...it is not known if LCMUFA also exerts anti‐atherogenic effects. The main objective of the present study was to investigate the effect of LCMUFA on the development of atherosclerosis in mouse models.
Methods and results
LDLR‐KO mice were fed Western diet supplemented with 2% (w/w) of either LCMUFA concentrate, olive oil, or not (control) for 12 wk. LCMUFA, but not olive oil, significantly suppressed the development of atherosclerotic lesions and several plasma inflammatory cytokine levels, although there were no major differences in plasma lipids between the three groups. At higher doses 5% (w/w) LCMUFA supplementation was observed to reduce pro‐atherogenic plasma lipoproteins and to also reduce atherosclerosis in ApoE‐KO mice fed a Western diet. RNA sequencing and subsequent qPCR analyses revealed that LCMUFA upregulated PPAR signaling pathways in liver. In cell culture studies, apoB‐depleted plasma from LDLR‐K mice fed LCMUFA showed greater cholesterol efflux from macrophage‐like THP‐1 cells and ABCA1‐overexpressing BHK cells.
Conclusion
Our research showed for the first time that LCMUFA consumption protects against diet‐induced atherosclerosis, possibly by upregulating the PPAR signaling pathway.
To investigate the effect of long‐chain monounsaturated fatty acid (LCMUFA) at least 20 carbons in length (i.e., C20:1 and C22:1 isomers combined) on atherosclerosis, a major cause of cardiovascular disease, two types of atherosclerotic mouse models were fed with LCMUFA‐rich diet for three months. In ApoE‐KO mice, 5% LCMUFA‐supplemented diet decreased plasma cholesterol, and suppressed atherosclerosis. In LDLR‐KO mice, a lower dose 2% LCMUFA also suppressed atherosclerosis and macrophage accumulation at aorta, although shorter‐chain MUFA oleic acid (C18:1)‐rich olive oil did not.
We investigated the effect of saury oil on the alleviation of metabolic syndrome in mice. Saury oil contains 18% (w/w/) n-3 polyunsaturated fatty acids (n-3 PUFA) and 35% (w/w) monounsaturated fatty ...acids (MUFA). Diabetic KKAy mice were fed a 10% soybean oil diet (control) or a 10% saury oil diet for 4 weeks, and diet-induced obese C57BL/6J mice were fed a high-fat diet containing 32% lard (control) or 22% lard plus 10% saury oil for 6 weeks. After the intervention periods, the levels of glucose, insulin and lipids in plasma had decreased significantly for the saury oil diet group, and insulin sensitivity had improved. These favorable changes may be attributed to the increased adiponectin and decreased TNFα and resistin levels in plasma. The saury oil diet also resulted in downregulated expression of the lipogenic genes (
SREBP
-
1
,
SCD
-
1
,
FAS
, and
ACC
) as well as upregulation of the fatty acid oxidative gene,
CPT
-
1
, and the energy expenditure-related genes (
PGC1α
and
PGC1β
) in white adipose tissue for the diet-induced obese C57BL/6J mice. An increase in n-3 PUFA levels and the concomitant decrease in the n-6/n-3 PUFA level ratio in serum, white adipose tissue, and liver with a saury oil diet are likely to be involved in the beneficial changes to the metabolic indicators. MUFA may also play a positive role in remodeling lipid composition. Based on these mice models, our results suggest a potential use for saury oil for improving metabolic abnormalities.
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