Lightning generated sferics: diagnostics tools to study upper atmosphere

Atmospherics or sferics that originate from lightning discharges on propagating large distances in the Earth-ionosphere waveguide or in the dispersive regions of ionosphere and magnetosphere form dispersed sferics called tweeks and whistlers respectively. Tweeks are novel diagnostic tool to monitor the nighttime D-region ionosphere. In this paper the lightning sferics (tweeks) recorded at a low latitude station, Suva (18.2o S,178.3oE, geomag. lat. 22.2o S, L = 1.17)) Fiji, in the South Pacific region and Allahabad (geomag. lat. 16.490 N, L=1.09) in India, will be presented and shown how they could be used to probe the night time D-region of the ionosphere. The computed D-region electron density is then compared with the electron density profile obtained from International Reference Ionosphere (IRI) 2007 model. Typical records of whistlers observed in Fiji and in India are presented

Coronal Mass Ejection-driven Shocks and the Associated Sudden Commencements-sudden Impulses

Interplanetary (IP) shocks are mainly responsible for the sudden compression of the magnetosphere, causing storm sudden commencement (SC) and sudden impulses (SIs) which are detected by ground-based magnetometers. On the basis of the list of 222 IP shocks compiled by Gopalswamy et al., we have investigated the dependence of SC/SIs amplitudes on the speed of the coronal mass ejections (CMEs) that drive the shocks near the Sun as well as in the interplanetary medium. We find that about 91% of the IP shocks were associated with SC/SIs. The average speed of the SC/SI-associated CMEs is 1015 km/s, which is almost a factor of 2 higher than the general CME speed. When the shocks were grouped according to their ability to produce type II radio burst in the interplanetary medium, we find that the radio-loud (RL) shocks produce a much larger SC/SI amplitude (average approx. 32 nT) compared to the radio-quiet (RQ) shocks (average approx. 19 nT). Clearly, RL shocks are more effective in producing SC/SIs than the RQ shocks. We also divided the IP shocks according to the type of IP counterpart of interplanetary CMEs (ICMEs): magnetic clouds (MCs) and nonmagnetic clouds. We find that the MC-associated shock speeds are better correlated with SC/SI amplitudes than those associated with non-MC ejecta. The SC/SI amplitudes are also higher for MCs than ejecta. Our results show that RL and RQ type of shocks are important parameters in producing the SC/SI amplitude

Evaluating diaphragmatic dysfunction and predicting non-invasive ventilation failure in acute exacerbation of chronic obstructive pulmonary disease in India

Background Baseline diaphragmatic dysfunction (DD) at the initiation of non-invasive ventilation (NIV) correlates positively with subsequent intubation. We investigated the utility of DD detected 2 hours after NIV initiation in estimating NIV failure in acute exacerbation of chronic obstructive pulmonary disease (AECOPD) patients. Methods In a prospective-cohort design, we enrolled 60 consecutive patients with AECOPD initiated on NIV at intensive care unit admission, and NIV failure events were noted. The DD was assessed at baseline (T1 timepoint) and 2 hours after initiating NIV (T2 timepoint). We defined DD as ultrasound-assessed change in diaphragmatic thickness (ΔTDI) <20% (predefined criteria [PC]) or its cut-off that predicts NIV failure (calculated criteria [CC]) at both timepoints. A predictive-regression analysis was reported. Results In total, 32 patients developed NIV failure, nine within 2 hours of NIV and remaining in the next 6 days. The ∆TDI cut-off that predicted NIV failure (DD-CC) at T1 was ≤19.04% (area under the curve [AUC], 0.73; sensitivity, 50%; specificity, 85.71%; accuracy; 66.67%), while that at T2 was ≤35.3% (AUC, 0.75; sensitivity, 95.65%; specificity, 57.14%; accuracy, 74.51%, hazard ratio, 19.55). The NIV failure rate was 35.1% in those with normal diaphragmatic function by PC (T2) versus 5.9% by CC (T2). The odds ratio for NIV failure with DD criteria ≤35.3 and <20 at T2 was 29.33 and 4.61, while that for ≤19.04 and <20 at T1 was 6, respectively. Conclusions The DD criterion of ≤35.3 (T2) had a better diagnostic profile compared to baseline and PC in prediction of NIV failure

Polymorphic Signature of the Anti-inflammatory Activity of 2,2′- {[1,2-Phenylenebis(methylene)]bis(sulfanediyl)}bis(4,6- dimethylnicotinonitrile)

Weak noncovalent interactions are the basic forces in crystal engineering. Polymorphism in flexible molecules is very common, leading to the development of the crystals of same organic compounds with different medicinal and material properties. Crystallization of 2,2′- {[1,2-phenylenebis(methylene)]bis(sulfanediyl)}bis(4,6-dimethylnicotinonitrile) by evaporation at room temperature from ethyl acetate and hexane and from methanol and ethyl acetate gave stable polymorphs 4a and 4b, respectively, while in acetic acid, it gave metastable polymorph 4c. The polymorphic behavior of the compound has been visualized through singlecrystal X-ray and Hirshfeld analysis. These polymorphs are tested for anti-inflammatory activity via the complete Freund’s adjuvant-induced rat paw model, and compounds have exhibited moderate activities. Studies of docking in the catalytic site of cyclooxygenase-2 were used to identify potential anti-inflammatory lead compounds. These results suggest that the supramolecular aggregate structure, which is formed in solution, influences the solid state structure and the biological activity obtained upon crystallization