We present measurements of radiocarbon in annual tree rings from the time period 980–1006 Common Era (C.E.), hereby covering the cosmic ray event in 994 C.E. The new radiocarbon record from Danish oak is based on both earlywood and latewood fractions of the tree rings, which makes it possible to study seasonal variations in 14C production. The measurements show a rapid increase of ∼10‰ from 993 to 994 C.E. in latewood, followed by a modest decline and relatively high values over the ensuing ∼10 years. This rapid increase occurs from 994 to 995 C.E. in earlywood, suggesting that the cosmic ray event most likely occurred during the period between April and June 994 C.E. Our new record from Danish oak shows strong agreement with existing Δ14C records from Japan, thus supporting the hypothesis that the 994 C.E. cosmic ray event was uniform throughout the Northern Hemisphere and therefore can be used as an astrochronological tie point to anchor floating chronologies of ancient history.
Objective:Chronic kidney disease (CKD) and arterial stiffness are associated with increased central (aortic) systolic blood pressure (cSBP) relative to brachial systolic blood pressure (bSBP). This study examined the impact of aortic calcification on cSBP relative to bSBP in patients with CKD.Design and method:Patients with or without CKD undergoing elective coronary angiography (CAG) at Aarhus University Hospital were considered for inclusion in this cross-sectional study. During CAG, cSBP was measured in the ascending aorta with a fluid-filled catheter while bSBP was measured simultaneously with an oscillometric device using a cuff. Furthermore, patients underwent a non-contrast computed tomography (CT) scan of the entire aorta with subsequent blinded Agatston-scoring of the aorta from (but excluding) the aortic valve to the aortic bifurcation. Carotid-femoral pulse wave velocity was measured in duplicate using a Sphygmocor device. Data are presented as mean ± standard deviation unless stated otherwise. Statistical comparisons were made using Wilcoxon rank sum test for differences between 2 groups and Bonferroni-adjusted Kruskal-Wallis test when testing for differences between > 2 groups.Results:149 patients were included in the study. Of these, 134 patients had a CT-scan of sufficient quality to allow analysis. Patient characteristics and measurements of BP and pulse wave velocity are presented in Table 1. Agatston-score was higher in CKD patients as compared to patients with normal kidney function (table 1, P < 0.001). bSBP was 6.5 ± 13.1 mmHg higher than cSBP in patients categorized into the first tertile of Agatston-scores. This difference was reduced to 3.3 ± 11.0 mmHg in the second tertile (p = 0.31, compared to first tertile) and -2.6 ± 16.8 mmHg in the third tertile (p < 0.01, compared to first tertile).Conclusions:Patients with CKD have a higher degree of aortic calcification. Furthermore, patients with a high degree of aortic calcification have a higher invasively measured cSBP as compared to the bSBP measured with an ordinary oscillometric BP device.
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