Two-dimensional structures of medium-scale traveling ionospheric disturbances (MSTIDs) over Europe have been revealed, for the first time, by using maps of the total electron content (TEC) obtained from more than 800 GPS receivers of the European GPS receiver networks. From statistical analysis of the TEC maps obtained 2008, we have found that the observed MSTIDs can be categorized into two groups: daytime MSTID and nighttime MSTID. The daytime MSTID frequently occurs in winter. Its maximum occurrence rate in monthly and hourly bin exceeds 70% at lower latitudes over Europe, whereas it is approximately 45% at higher latitudes. Since most of the daytime MSTIDs propagate southward, we speculate that they could be caused by atmospheric gravity waves in the thermosphere. The nighttime MSTIDs also frequently occur in winter but most of them propagate southwestward, in a direction consistent with the theory that polarization electric fields play an important role in generating the nighttime MSTIDs. The nighttime MSTID occurrence rate shows distinct latitudinal difference: The maximum of the occurrence rate in monthly and hourly bin is approximately 50% at lower latitudes in Europe, whereas the nighttime MSTID was rarely observed at higher latitudes. We have performed model calculations of the plasma density perturbations caused by a gravity wave and an oscillating electric field to reproduce the daytime and nighttime MSTIDs, respectively. We find that TEC perturbations caused by gravity waves do not show dip angle dependencies, while those caused by the oscillating electric field have a larger amplitude at lower latitudes. These dip angle dependencies of the TEC perturbation amplitude could contribute to the latitudinal variation of the MSTID occurrence rate. Comparing with previous studies, we discuss the longitudinal difference of the nighttime MSTID occurrence rate, along with the E- and F-region coupling processes. The seasonal variation, of the nighttime MSTID occurrence rate in Europe, is not consistent with the theory that the longitudinal and seasonal variations of the nighttime MSTID occurrence could be attributed to those of the Es layer occurrence
BACKGROUND: A self-administered questionnaire on dietary habits used in the JACC Study contained a 40-item food frequency questionnaire (FFQ). Although more than 110 thousand subjects enrolled in JACC Study and responded to the FFQ, no validation study has been conducted to date. METHODS: Eighty-five volunteers among the cohort members completed 2 FFQs (FFQs 1&2) and 12-day weighed dietary records (WDR). The interval between the two FFQs was one year. During the one year, the subjects carried out a 3-consecutive-day WDR in each season. We tested the reproducibility by using two FFQs. Also, we tested the validity of the FFQ by using the 12-day WDR as a gold standard. RESULTS: The intake frequencies of the 2 FFQs often agreed, showing the Spearman correlation coefficients ranging from 0.42 (edible wild plants) to 0.86 (coffee). The Spearman correlation coefficients of the energy and nutrient intakes from FFQ2, and that of the 12-day WDR were 0.20(energy) to 0.46 (animal protein, potassium). After adjusting the energy intake, the correlation coefficients showed 0.21(fish fat) to 0.51(animal fat). When classifying the FFQ2 and WDR by quartiles and examining the degree of agreement between the two methods, we obtained its median 30%. CONCLUSIONS: The FFQ is suitable to deal with a large group of subjects. However, since the energy and the amount of nutrient intake from this FFQ can not show the overall dietary intake situation, the subjects’ dietary intake should be assessed by categories.
We studied the synergistic effects of stem cell factor (SCF) and other burst-promoting activities (BPAs) such as interleukin-3 (IL-3), granulocyte-macrophage colony-stimulating factor (GM-CSF), or IL-9 on proliferation of human peripheral blood-derived highly purified progenitors. SCF, IL-3, GM-CSF, and IL-9 showed significant BPA when CD34+HLA-DR+ cells were used as the target population. IL-3 exerted the most potent BPA, and GM-CSF supported approximately 40% to 70% of the erythroid burst-forming units that are responsive to IL-3. SCF and IL-9 showed much weaker BPA than that of IL-3 or GM-CSF. Combinations of IL- 3 with other BPAs did not show synergistic actions supporting erythroid- burst formation. However, GM-CSF showed a significant additive effect with IL-9 or SCF. When CD34+c-kithigh cells were used as the target, SCF showed a much stronger BPA. Also, a distinct additive effect between SCF and IL-3 or GM-CSF on erythrocyte-containing mixed colony formation was observed. On the other hand, when CD34+c-kitlow cells were used as the target, SCF, IL-3, and GM-CSF could express BPA. In contrast, IL-9 alone failed to support erythroid-burst formation. Because CD34+c-kithigh cells weakly expressed CD34 antigen, these cells appeared to be more mature progenitors than CD34+c-kitlow cells. These results suggest that IL-9 acts on more mature progenitors than those of SCF, IL-3, or GM-CSF and that the primary target of SCF is multipotential progenitors at the very early stage of development.
We studied the effect of human flt3/flk2 ligand (FL) on the proliferation and differentiation of purified CD34+ blood progenitors which express different levels of c‐kit protein in clonal cell culture in comparison with that of stem cell factor (SCF). FL alone did not support significant colony formation. However, FL significantly enhanced neutrophil colony (CFU–G) formation in the presence of granulocyte‐colony stimulating factor (G–CSF) by peripheral blood (PB)‐derived CD34+c‐kit− cells which contained a large number of CFU–G. In addition, FL could synergistically increase the number of CFU–G supported by a combination of interleukin (IL)‐3 and G–CSF, as did SCF. As we reported previously, SCF showed a significant burst‐promoting activity (BPA). In contrast, FL did not exhibit any BPA on PB‐derived CD34+c‐kithigh cells in which erythroid‐burst (BFU‐E) was highly enriched. However, FL could synergize with IL‐3 or GM–CSF in support of erythrocyte‐containing mixed (E‐Mix) colony by PB‐derived CD34+c‐kithigh or low cells in the presence of Epo. Replating of E‐Mix colonies derived from CD34+c‐kithigh cells supported by IL‐3+Epo+SCF yielded more secondary colonies than those supported by IL‐3+Epo or IL‐3+Epo+FL. When PB‐derived CD34+c‐kitlow cells which represent a more immature population than CD34+c‐kithigh cells were used as the target, number of secondary colonies supported by IL‐3+Epo, IL‐3+Epo+SCF or IL‐3+Epo+FL was comparable. However, the number of lineages expressed in the secondary culture was significantly larger in the primary culture containing IL‐3+Epo+FL than in that containing IL‐3+Epo. These results suggest that FL not only acts on neutrophilic progenitors, but also on more immature multipotential progenitors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.