Evaluation of Potential Predictability of Indian Summer Monsoon Rainfall in ECMWF's Fifth-Generation Seasonal Forecast System (SEAS5)

Forecasts of Indian summer monsoon rainfall (ISMR: June to September, JJAS) are issued prior to the onset of rainy season. Thus, an assessment of both potential and actual forecast skills for Indian summer monsoon rainfall should be based on a longer lead time. Based upon the European Center for Medium Range Weather Forecasts (ECMWF) fifth-generation seasonal forecast system (SEAS5), two lead times are considered: one with an April initial condition (IC) and the other with a May IC from 1981 through 2019 (39 years). Our results show that SEAS5 successfully represents the spatial patterns and variations in the mean JJAS precipitation in the ISMR region compared with the observed rainfall patterns. However, there seem to be significant discrepancies in the simulation of mean precipitation, particularly over topographical regions. SEAS5 is capable of reproducing the observed annual precipitation cycle in India. Moreover, the model is able to better predict the realistic ISMR teleconnections with El Nin˜o-Southern Oscillation and the Indian Ocean Dipole at May ICs. The resulting forecasts across the region are characterized by moderate significant potential and actual skill in both leads, and it decreases as lead time increases. The predictability of SEAS5 is directly related to its ability to correctly predict the forcing of the tropical sea surface temperature and its teleconnections. In spite of this, both lead forecasts have a significant number of unpredicted events and false alarms. This study highlights model discrepancies, shows poor performance in predicting ISMR, and highlights the need for further research on this crucial issue of social relevance

Electrospun polylactic acid-chitosan composite: a bio-based alternative for inorganic composites for advanced application

Fabricating novel materials for biomedical applications mostly require the use of biodegradable materials. In this work biodegradable materials like polylactic acid (PLA) and chitosan (CHS) were used for designing electrospun mats. This work reports the physical and chemical characterization of the PLA-CHS composite, prepared by the electrospinning technique using a mixed solvent system. The addition of chitosan into PLA, offered decrease in fiber diameter in the composites with uniformity in the distribution of fibers with an optimum at 0.4wt% CHS. The fiber formation and the reduction in fiber diameter were confirmed by the SEM micrograph. The inverse gas chromatography and contact angle measurements supported the increase of hydrophobicity of the composite membrane with increase of filler concentration. The weak interaction between PLA and chitosan was confirmed by Fourier transform infrared spectroscopy and thermal analysis. The stability of the composite was established by zeta potential measurements. Cytotoxicity studies of the membranes were also carried out and found that up to 0.6% CHS the composite material was noncytotoxic. The current findings are very important for the design and development of new materials based on polylactic acid-chitosan composites for environmental and biomedical applications.info:eu-repo/semantics/publishedVersio

Polylactic acid/nano chitosan composite fibers and their morphological, physical characterization for the removal of cadmium(II) from water

This work discusses the fabrication of polylactic acid (PLA)/nano chitosan (nCHS) composite fibers by electrospinning method for Cd2+ metal ion adsorption from water. Here nCHS was synthesized by ionic gelation method and which is used as a reinforcement for PLA. The scanning electron microscopic analysis revealed that the addition 0.1 wt% nCHS has decreased the fiber diameter as well as the secondary pore size and hence imparted unique properties to electrospun composite fibers. The positive zeta potential values for the composites indicated their higher stability, though; the inclusion of nCHS reduced the crystallinity of the neat membranes. The contact angle measurements showed that the hydrophilicity of the composite was increased up to 0.1 wt% nCHS, and hence the surface energy was increased. Inverse gas chromatography results suggested that the basic character of the composites has intensified with the increase in nCHS addition. The adsorption capacity of the neat electrospun PLA and PLA–nCHS composites for Cd2+ ions were investigated and studies revealed that adsorption capacity of the composite was two times faster (approximately 70%) in comparison with neat PLA fibers. The increase in surface area as well as presence nCHS improved the adsorption capacity of the electrospun membrane.info:eu-repo/semantics/publishedVersio

Studies on the Role of Tropospheric Biennial Oscillation in the Interannual Variability of Indian Summer Monsoon

The present study illustrates the biennial oscillation in different ocean-atmosphere parameters associated with interannual variability of Indian summer monsoon rainfall.It also accounts the role of different processes like ENSO, IOD, QBO and ISO in the monsoon variability during the TBO years.Department of Atmospheric Sciences, Cochin University of Science and Technolog

Parameter Estimation of Organic Photovoltaic Cells - A Three-Diode Approach Using Wind-Driven Optimization Algorithm

Modeling a reliable electrical equivalent circuit to simulate the output I-V characteristics of organic solar PV (OPV) cells still prevails as a challenging task. This is because, estimating unknown parameters from the transcendental current equation determining the nonlinear OPV characteristics is extremely difficult. More importantly, predicting the parameters for dynamic changes in irradiation profile demands reliable optimization-based models. Therefore, this article proposes the application of adaptive wind-driven optimization (WDO) algorithm for a three-diode electrical equivalent model to estimate the OPV circuit parameters. Application of WDO algorithm has produced precise PV parameters to reproduce the exact I-V characteristics. In particular, the ability to replicate the kink effect in OPV characteristics is a noticeable improvement. Compared to its counterparts, various factors that enable WDO to enhance its compatibility towards nonlinear OPV modeling are: i) unique velocity update strategy via Coriolis and Gravitational forces, ii) excellent tradeoff between exploration and exploitation of control variables, iii) adaptive capability to maintain solutions within the search space even if the limits are breached, and iv) easiness in parameter tuning. For the validation, extensive testing has been conducted to reproduce the widely used characteristics of nav100 OPV cell at various operating conditions. Quantitatively, WDO method showcases excellent accuracy with an individual absolute error value in the order of 10-6 and convergence within the first 50 iterations itself, demonstrating its supremacy to solve OPV parameter identification problem

Inter-annual variability and skill of tropical rainfall and SST in APCC seasonal forecast models

International audienceThe present study explored the performance of the current coupled models obtained from the Asia Pacific Economic Cooperation (APEC) Climate Centre (APCC) in representing the tropical Indo-Pacific sea surface temperature (SST) and rainfall during boreal summer season (June through September; JJAS). We have used the retrospective/hindcast runs for 28 years from 1983 to 2010 initialized in May. The mean SST bias in the tropical Indo-Pacific Oceans showed large diversity among the models in JJAS. In the case of the rainfall, most of the models displayed a strong dry bias over the major continental regions and wet biases over the tropical oceans. The majority of the models simulated the Inter-annual variability (IAV) of JJAS rainfall and SST reasonably well over the equatorial Pacific region, where the models are close to observed IAV and maximum signal to noise ratio (SNR). It is found that the models display, low IAV of rainfall and SST over the Indian Ocean with low SNR values, resulting in less predictive skill as compared to the tropical Pacific region. Similarly, all models showed a higher skill in summer rainfall prediction over the oceanic regions compared to the Asian land region, where SNR is very low. Further analysis suggested that the models have greater skill in predicting El Niño-Southern Oscillation (ENSO). The category wise analysis showed that models could predict 60–70% of the extreme ENSO events, but the normal events are represented only by 50%. It is noted that the models predict many false alarms for El Niño resulting in a higher frequency of El Niño occurrence. This is mainly responsible for stronger ENSO and the Asian Monsoon teleconnections in the models than in the observations. Meanwhile, the category wise rainfall skill for extended Indian monsoon region (EMR) displayed 50–60% accuracy for the extreme monsoon years and is around 50% for normal years. However, models such as CCSM3, CFSV2, and CANCM3 have displayed higher rainfall skills over EMR as compared to the other models possibly due to better representation of teleconnections spatial patterns between EMR rainfall and SST anomalies over Indo-Pacific Oceans

Stem-Cell Therapy for Bronchopulmonary Dysplasia (BPD) in Newborns

Premature newborns are at a higher risk for the development of respiratory distress syndrome (RDS), acute lung injury (ALI) associated with lung inflammation, disruption of alveolar structure, impaired alveolar growth, lung fibrosis, impaired lung angiogenesis, and development of bronchopulmonary dysplasia (BPD) with severe long-term developmental adverse effects. The current therapy for BPD is limited to supportive care including high-oxygen therapy and pharmacotherapy. Recognizing more feasible treatment options to improve lung health and reduce complications associated with BPD is essential for improving the overall quality of life of premature infants. There is a reduction in the resident stem cells in lungs of premature infants with BPD, which strongly suggests a critical role of stem cells in BPD pathogenesis; this warrants the exploration of the potential therapeutic use of stem-cell therapy. Stem-cell-based therapies have shown promise for the treatment of many pathological conditions including acute lung injury and BPD. Mesenchymal stem cells (MSCs) and MSC-derived extracellular vesicles (EVs) including exosomes are promising and effective therapeutic modalities for the treatment of BPD. Treatment with MSCs and EVs may help to reduce lung inflammation, improve pulmonary architecture, attenuate pulmonary fibrosis, and increase the survival rate