Spatio-temporal characterization of drought variability in data-scarce regions using global precipitation data: a case study in Cauto river basin, Cuba.

Drought is considered the most severe water-related disaster in the Cauto river basin, which is the longest river and the main agricultural producer in Cuba. Better understanding of drought characteristics is crucial to drought management. Given the sparsity of ground-based precipitation observations in the Cauto, this study aims at using gridded global precipitation to analyze the spatio-temporal variations of drought in this river basin. Firstly, the monthly Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) was calibrated with the gauged precipitation using the Thiessen polygon-based method and linear least squares regression equations. Then, the gridded standardized precipitation index (SPI) with time scales of 3, 6, 9 months and drought characteristics, namely, drought frequency, duration and intensity were calculated using the calibrated CHIRPS. Finally, the spatio-temporal analysis was performed to investigate the variations of drought in the Cauto river basin in time and space. The obtained results show that the calibrated CHIRPS is highly consistent with the gauged observations and is capable of determining the magnitude, time, and spatial extent of drought events in the Cauto river basin. The trend analysis by the Mann-Kendall test reveals that although the trend is not statistically significant, the SPI tends to decrease with time in the dry season, which indicates the more severe drought. The spatial analysis indicates that the lower altitude area of the Cauto river basin is suffered from longer drought duration and higher drought intensity than the upper one. This study expresses the importance of open global precipitation data sources in monitoring and quantifying drought characteristics in data-scarce regions.

Bayesian merging of numerical modeling and remote sensing for saltwater intrusion quantification in the Vietnamese Mekong Delta.

Saltwater intrusion has become one of the most concerning issues in the Vietnamese Mekong Delta (VMD) due to its increasing impacts on agriculture and food security of Vietnam. Reliable estimation of salinity plays a crucial role to mitigate the impacts of saltwater intrusion. This study developed a hybrid technique that merges satellite imagery with numerical simulations to improve the estimation of salinity in the VMD. The salinity derived from Landsat images and by numerical simulations was fused using the Bayesian inference technique. The results indicate that our technique significantly reduces the uncertainties and improves the accuracy of salinity estimates. The Nash-Sutcliffe coefficient is 0.74, which is much higher than that of numerical simulation (0.63) and Landsat estimation (0.6). The correlation coefficient between the ensemble and measured salinity is relatively high (0.88). The variance of the ensemble salinity errors (5.0 ppt2) is lower than that of Landsat estimation (10.4 ppt2) and numerical simulations (9.6 ppt2). The proposed approach shows a great potential to combine multiple data sources of a variable of interest to improve its accuracy and reliability wherever these data are available.

Impact of work routines on parents' and children's sleep during the COVID-19 pandemic lockdown.

OBJECTIVE: To evaluate the effects of parental sleep and work arrangements on children's sleep duration during the national lockdown period, referred to as 'Circuit Breaker' (CB), due to COVID-19. METHODS: Cross-sectional, anonymous, online questionnaire to parents with school-going children aged between 3 and 16 years. Child and parental sleep duration in relation to change in parental work arrangements, housing type and number of individuals in the household as reported by parents were evaluated. Descriptive statistics and tests of comparison were used to evaluate data. RESULTS: School-going children (n = 593) had a mean age of 8.68 (SD = 3.65; median 7) years. Both, fathers and mothers had gains in sleep during CB (based on self-reported sleep data), compared to pre-CB. Change in both maternal and paternal sleep duration positively correlated with change in child sleep duration (based on parent-reported sleep data) among all children (r2 = 0.27, p < 0.001 and r2 = 0.17, p < 0.001 respectively); pre-schoolers mirrored their mothers' sleep more closely. Parents who changed to working from home during the CB (compared to working from outside home previously) had the greatest gains in sleep during this period. Housing type was not significantly associated with change in child sleep duration from pre-CB to CB. CONCLUSIONS: Greater gains in sleep in parents was associated with working from home during CB. Child sleep duration mirrored gains in parental sleep, especially in pre-school and primary-school-going children. Optimising parental sleep may therefore be one of the means to improve child sleep.

School closure during the coronavirus disease 2019 (COVID-19) pandemic - Impact on children's sleep.

OBJECTIVE: To evaluate the sleep habits of school-going children before and during school closure in the national lockdown period (called 'Circuit Breaker' or CB in Singapore) due to the COVID-19 pandemic. METHODS: Cross-sectional, anonymous, online, population-based survey questionnaire was administered to parents aged 21 years and above with children aged between 3 and 16 years attending pre-school, primary or secondary school (equivalent to kindergarten, middle and-high school) and residing in Singapore. Sleep duration in relation to various daily activities including academic activities, physical exercise, and screen time was evaluated pre-CB and during CB. RESULTS: Data from 593 participants were analyzed. Pre-CB, the overall mean (SD) sleep duration of the study population was 9.01 (1.18) hours on weekdays and 9.99 (0.94) hours on weekends. During CB, mean (SD) sleep duration overall was 9.63 (1.18) hours. Although children generally went to bed later (mean 0.65 h later), they woke up even later during CB (mean 1.27 h later), resulting in longer sleep duration (mean increase of 0.35 h). This was most evident in secondary school children (mean increase of 0.70 h). Children attending private schools (which had later start times) had increased sleep duration (mean 10.01 (SD 0.89) hours pre-CB and 10.05 (SD 0.93) hours during CB) compared to public schools (mean 9.05 (SD 0.91) pre-CB and 9.49 (SD 1.22) hours during CB). CONCLUSIONS: School closure from the COVID-19 pandemic resulted in longer sleep duration in school-going children. Early school/academic activity start times had a significant impact on limiting children's sleep duration.

Combined Interventions for Nonorganic Visual Loss in a Case with Pseudo-Myopia: A Perspective from Vietnam.

A previously healthy 10-year-old girl developed painless visual loss. She was diagnosed with a spasm of accommodation confirmed by cycloplegic refraction. She was prescribed low-dose atropine and again reported acute visual loss that was inconsistent with the level of daily function. She was referred to a pediatric psychiatrist with suspicion for a nonorganic visual disorder and was diagnosed with conversion disorder. She received psychotherapy and continued the treatment with low-dose atropine. Her visual acuity at distance returned to normal. Psychogenic visual loss can mimic organic disorders; hence, ophthalmologists should be aware of cases without the agreement between visual signs and daily manifestation.

Ocular Biometrics of Vietnamese Young Adults with Myopia.

BACKGROUND: Myopia is most prevalent type of refraction error. In some Asian countries, the prevalence of myopia can be 80 - 90% in the population aged 17 - 18. AIM: To analyze the correlation between ocular biometric indices and refraction status in Vietnamese young myopes. METHODS: A prospective cross - section study was conducted in young myopes. Data on axial length, central cornea thickness, corneal topography & anterior chamber depth and spherical equivalent were collected. Independent Sample T Test and ANOVA test were used to compare between groups. The correlations between ocular biometry and myopic spherical equivalent refraction were examined by Pearson Correlation with the level of significance p < 0.05. RESULTS: Totally, 418 eyes from 209 patients were recruited. The average axial length, central cornea thickness, cornea refraction & anterior chamber depth were 25.68 ± 1.09 mm, 539.78 ± 32.665 µm, 43.16 ± 1.369 D, 3.30 ± 0.243 mm, respectively. The correlation between axial length and spherical equivalent refraction (SER) was high (r = - 0.742, p < 0.0001) while those between central cornea thickness and cornea refraction were negligible (r = - 0.107, p = 0.029; r = -0.123, p = 0.012; respectively). There was no correlation between anterior chamber depth and spherical equivalent refraction (r = 0.019, p = 0.697). CONCLUSION: Among ocular biometric indices, axial length was significantly correlated with spherical equivalent of young adult patients.