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Abstract: It has been a long‐standing debate on the nature of Elsässer variable z− observed in the solar wind fluctuations. It is widely believed that z− represents inward propagating Alfvén waves and interacts nonlinearly with z+ (outward propagating Alfvén waves) to generate energy cascade. However, z− variations sometimes show a feature of convective structures. Here we present a new data analysis on autocorrelation functions of z− in order to get some definite information on its nature. We find that there is usually a large drop on the z− autocorrelation function when the solar wind fluctuations are highly Alfvénic. The large drop observed by Helios 2 spacecraft near 0.3 AU appears at the first nonzero time lag τ = 81 s, where the value of the autocorrelation coefficient drops to 25%–65% of that at τ = 0 s. Beyond the first nonzero time lag, the autocorrelation coefficient decreases gradually to zero. The drop of z− correlation function also appears in the Wind observations near 1 AU. These features of the z− correlation function may suggest that z− fluctuations consist of two components: high‐frequency white noise and low‐frequency pseudo structures, which correspond to flat and steep parts of z− power spectrum, respectively. This explanation is confirmed by doing a simple test on an artificial time series, which is obtained from the superposition of a random data series on its smoothed sequence. Our results suggest that in highly Alfvénic fluctuations, z− may not contribute importantly to the interactions with z+ to produce energy cascade. [ABSTRACT FROM AUTHOR]

Abstract: The spectral break (fb) of magnetic fluctuations at the ion scale in the solar wind is considered to give important clue on the turbulence dissipation mechanism. Among several possible mechanisms, the most notable two are related respectively to proton thermal gyroradius ρi and proton inertial length di. The corresponding frequencies of them are fρi=VSW/(2πρi) and fdi=VSW/(2πdi), respectively, where VSW is the solar wind speed. However, no definite conclusion has been given for which one is more reasonable because the two parameters have similar value when plasma beta β ∼ 1. Here we do a statistical study to see if the two ratios fb/fρi and fb/fdi have different dependence on β in the solar wind turbulence with 0.1 < β < 1.3. From magnetic measurements by the Wind spacecraft, we select 141 data sets with each one longer than 13 h. We find that the ratio fb/fdi is statistically not dependent on β, and the average value of it is 0.48 ± 0.06. However, fb/fρi increases with increasing β clearly and is significantly smaller than fb/fdi when β < 0.8. These new results show that fb is statistically 0.48fdi, and the influence of β could be negligible in the studied β range. It indicates a preference of the dissipation mechanism associated with di in the solar wind with 0.1 < β < 0.8. Further theoretical studies are needed to give detailed explanation. [ABSTRACT FROM AUTHOR]

The end-of-century projection of the snowfall characteristics over the Alps region is studied using the 50-km resolution atmospheric global climate model, HiRAM (high-resolution atmospheric model). The model is forced by three different patterns of projections in the sea surface temperature ( SST) in order to assess the sensitivity of snowfall characteristics to theses patterns. It is found that the mean snowfall intensity and frequency is poorly affected by the differences in SST forcing. However, the projections of heavy snowfall events strongly depend on the SST scenario. The changes in temperature and frequency of precipitation and freezing days over the Alps were investigated. We found that these variables did not exhibit a clear dependence to the SST scenario and could not explain the differences observed in snowfall projections. Changes in the moisture transport from the Atlantic Ocean to Europe were found significantly different between each scenario and are assumed to be the main factor affecting the projections of snowfalls, by providing more or less moisture supply. [ABSTRACT FROM AUTHOR]

Background and purpose Chronic obstructive pulmonary disease ( COPD) is frequently associated with various comorbidities. However, the proportion of COPD patients with dementia has not been adequately examined. This retrospective cohort study investigated the association between COPD and dementia by using a nationwide population-based database in Taiwan. Methods Data were retrieved from the Taiwanese National Health Insurance Research Database and analyzed using multivariate Cox proportional hazards regression models to assess the effects of COPD on the risk of dementia after adjusting for demographic characteristics and comorbidities. Results The COPD cohort exhibited a higher prevalence of diabetes, hypertension, coronary artery disease, head injury and depression at baseline than did the non- COPD cohort ( P < 0.0001). After adjusting for covariates, the COPD patients exhibited a 1.27-fold higher risk of developing dementia (hazard ratio 1.27, 95% confidence interval 1.20-1.36). The incidence rate was higher in patients with frequent acute exacerbations than in the non- COPD patients regardless of whether a hospital admission or emergency room visit was required (hazard ratio 196.8 vs. 41.7, 95% confidence intervals 145.9-265.5 and 22.3-78.0). Conclusion This study shows that COPD is associated with a subsequent higher risk of dementia after adjusting for comorbidities. Specifically, the association between COPD and dementia is greater in patients with more frequent acute exacerbation events of COPD. [ABSTRACT FROM AUTHOR]

A response is presented by the authors to a letter to the editor about their article "The association between chronic obstructive pulmonary disease and dementia: A population-based retrospective cohort study."