Ionosphere: A Month Campaign over Sipitang and Parit Raja Stations, Malaysia

Ionospheric scintillations, which cause significant effects on satellite signals for communication and navigation, often takes place in equatorial region such as Malaysia. However, this disturbance are not fully understand due to few studies performed. This research reports the study and monitoring activity on Total Electron Content (TEC) and ionospheric scintillation in Malaysia using GPS measurements. Approach: One dual-frequency GPS receiver was positioned at the main station in Parit Raja, West Malaysia (1.86° N, 103.8° E) and Sipitang, East Malaysia (5.10° N, 115.56° E) respectively. Dual-frequency GPS data collected during the one-month ionospheric experimental campaign was used for TEC and scintillation computation and analysis. The TEC with 15 sec interval were computed from combined L1 and L2 code-pseudorange and carrier phase measurements. Whereas, the scintillation parameter S4 index was computed as a standard deviation of the received signal power normalized to average signal power every 60 sec on L1. A corrected S4 (without noise effects) was also computed and used in the analysis. Results: It was found that the daily maxima vTEC for Parit Raja (PR) ranged from 38-100 TECU, which is generally higher than those of Sipitang, which ranged from 30-42 TECU. However, a general consistency for both stations can be seen during the 1 month campaign period. Conclusions/Recommendations: In conclusion, these results show good agreement in the existence of the equatorial anomaly observed during moderate solar flux conditions and undisturbed geomagnetic condition. This will contributes to the knowledge of equatorial ionosphere and help in space weather condition. However, to better understand and characterize the ionosphere over Malaysia, more campaigns should be encouraged

Association of respiratory symptoms and lung function with occupation in the multinational Burden of Obstructive Lung Disease (BOLD) study

Background Chronic obstructive pulmonary disease has been associated with exposures in the workplace. We aimed to assess the association of respiratory symptoms and lung function with occupation in the Burden of Obstructive Lung Disease study. Methods We analysed cross-sectional data from 28 823 adults (≥40 years) in 34 countries. We considered 11 occupations and grouped them by likelihood of exposure to organic dusts, inorganic dusts and fumes. The association of chronic cough, chronic phlegm, wheeze, dyspnoea, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1)/FVC with occupation was assessed, per study site, using multivariable regression. These estimates were then meta-analysed. Sensitivity analyses explored differences between sexes and gross national income. Results Overall, working in settings with potentially high exposure to dusts or fumes was associated with respiratory symptoms but not lung function differences. The most common occupation was farming. Compared to people not working in any of the 11 considered occupations, those who were farmers for ≥20 years were more likely to have chronic cough (OR 1.52, 95% CI 1.19–1.94), wheeze (OR 1.37, 95% CI 1.16–1.63) and dyspnoea (OR 1.83, 95% CI 1.53–2.20), but not lower FVC (β=0.02 L, 95% CI −0.02–0.06 L) or lower FEV1/FVC (β=0.04%, 95% CI −0.49–0.58%). Some findings differed by sex and gross national income. Conclusion At a population level, the occupational exposures considered in this study do not appear to be major determinants of differences in lung function, although they are associated with more respiratory symptoms. Because not all work settings were included in this study, respiratory surveillance should still be encouraged among high-risk dusty and fume job workers, especially in low- and middle-income countries.publishedVersio