The spatial variability of the soil C:N ratio (C:N) influences C and N leaching and basic fertility in the field. This paper aims to identify the spatial heterogeneity of C:N in a Mollisol watershed of Northeast China and determine the main mechanisms that drive these differences. A random sampling method was used, with both geostatistical and traditional analysis being used to describe the spatial distribution of the C:N at various depths. C:N was also compared between slope position, previous vegetation and tillage methods in the watershed. The horizontal distribution of the C:N was mainly influenced by structural factors (88·4-99·9%) and often gradually deceased along the hydrographic flow direction, becoming lowest at the watershed outlet. The C:N increased as soil depth increased at all slope positions, and was higher on the back slope than on summit slope, followed by bottom slope in all soil depths. C:N was negatively (significant at p < 0·01) correlated to TN, and positively (significant at p < 0·05) correlated to elevation at all soil depths. Compared to the reforested area, C:N was typically greater in the agricultural area in the 20-60 cm depth. The planting of soybean (Glycine max L) can significantly increase the C:N at the 40-50 cm depth. C:N was higher in cross-slope tillage than in down-slope tillage, especially at soil depths of 40-50 cm. Generally, topographical factors, land use, crop planting and tillage methods can effectively influence the spatial heterogeneity of C:N in this watershed.

Background The influences of low‐carbohydrate diets in cardiovascular disease are controversial. Few studies have examined the relationship of carbohydrate intake and risk of incident atrial fibrillation ( AF ). We aimed to evaluate the association between carbohydrate intake and the risk of incident AF in the ARIC (Atherosclerosis Risk in Communities) Study. Methods and Results We included 13 385 participants (age, 54.2±5.8 years; 45.1% men and 74.7% white) who completed a dietary questionnaire at baseline (1987–1989) in the ARIC Study. The primary outcome was incident AF , which was identified by ECG performed during study examinations, hospital discharge codes, and death certificates. We used multivariable Cox hazard regression models to assess the association between carbohydrate intake and incident AF . We further explored the effects of specific food source (animal versus plant based) used to replace carbohydrate intake in the low‐carbohydrate intake setting. During a median follow‐up of 22.4 years, 1808 cases (13.5%) of AF occurred. The hazard ratio for incident AF associated with a 1‐ SD (9.4%) increase in carbohydrate intake as a percentage of energy intake was 0.82 (95% CI , 0.72–0.94), after adjustment for traditional AF risk factors and other diets factors. Results were similar when individuals were categorized by carbohydrate intake quartiles (hazard ratio, 0.64; 95% CI , 0.49–0.84; comparing extreme quartiles). No association was found between the type of protein or fat used to replace the carbohydrate and risk of incident AF . Conclusions Low‐carbohydrate diets were associated with increased risk of incident AF , regardless of the type of protein or fat used to replace the carbohydrate.

Background The association between blood pressure control and clinical outcomes is unclear among patients with heart failure with preserved ejection fraction. Both too high and too low of systolic blood pressure (SBP) have been reported to be related to poor clinical prognosis. This study aimed to assess the association between time in SBP target range and adverse clinical events among patients with heart failure with preserved ejection fraction. Methods and Results This study was a secondary analysis of the TOPCAT (Treatment of Preserved Cardiac Function Heart Failure With an Aldosterone Antagonist) trial, a randomized clinical trial that compared the efficacy and safety of spironolactone in patients with heart failure with preserved ejection fraction. Time in target range (TTR) was calculated using linear interpolation, with the target range of SBP defined as 110 to 130 mm Hg. The association between TTR with adverse outcomes was estimated using multivariable Cox regression to adjust for multiple confounders. Participants with greater TTR were younger, more likely to be White, had less comorbidities, and lower body mass index. After adjusting for multiple covariates including mean SBP, 1‐SD increment (38.3%) of TTR was significantly associated with a decreased risk of primary composite end point (hazard ratio [HR], 0.81 [0.73–0.90]), as well as a lower risk of all‐cause mortality (HR, 0.81 [0.73–0.90]), cardiovascular death (HR, 0.78 [0.68–0.90]), and heart failure hospitalization (HR, 0.85 [0.74–0.97]). Results were similar when participants were categorized by TTR groups. Subgroup analyses showed that the associations were more significant in young people than in the old ( P interaction =0.028). Conclusions In patients with heart failure with preserved ejection fraction, greater time in SBP target range was statistically associated with a decreased risk of cardiovascular outcomes and mortality events beyond blood pressure level, especially among younger patients.