Variation of electron and ion density distribution along earth's magnetic field line deduced from whistler mode (wm) sounding of image/rpi satellite below altitude 5000 km

Thesis (Ph.D.) University of Alaska Fairbanks, 2015This thesis provides a detailed survey and analysis of whistler mode (WM) echoes observed by IMAGE/RPI satellite during the years 2000-2005 below the altitude of 5000 km. Approximately 2500 WM echoes have been observed by IMAGE during this period. This includes mostly specularly reflected whistler mode (SRWM) echoes and ~400 magnetospherically reflected whistler mode (MRWM) echoes. Stanford 2D raytracing simulations and the diffusive equilibrium density model have been applied to 82 cases of MRWM echoes, observed during August-December of the year 2005 below 5000 km to determine electron and ion density measurements along Earth's magnetic field line. These are the first results of electron and ion density measurements from WM sounding covering L-shells ~1.6-4, a wide range of geomagnetic conditions (Kp 0+ to 7), and during solar minima (F10.2~70-120) in the altitude range 90 km to 4000 km. The electron and ion density profiles obtained from this analysis were compared with in situ measurements on IMAGE (passive recording; electron density (Ne)), DMSP (~850 km; Ne and ions), CHAMP (~350 km; Ne), Alouette (~500-2000 km; Ne and ions), ISIS-1, 2 (~600-3500 km; Ne, ions), AE (~130-2000 km; ions) satellites, bottom side sounding from nearby ionosonde stations (Ne), and those by GCPM (Global Core Plasma Model), IRI-2012 (International Reference Ionosphere). Based on this analysis it is found that: (1) Ne shows a decreasing trend from L-shell 1.6 to 4 on both the day and night sides of the plasmasphere up to altitude ~1000 km, which is also confirmed by the GCPM and IRI-2012 model. (2) Above ~2000 km altitude, GCPM underestimates Ne by ~30-90% relative to RPI passive measurements, WM sounding results. (3) Below 1500 km, the Ne is higher at day side than night side MLT (Magnetic Local Time). Above this altitude, significant MLT dependence of electron density is not seen. (4) Ion densities from WM sounding measurements are within 10-35% of those from the Alouette, AE, and DMSP satellites. (5) The effective ion mass in the day side is more than two times higher than night side below altitude ~500 km. (6) The O⁺/H⁺ and O⁺/(H⁺+H⁺+) transition heights at day side are ~300-500 km higher than night side; the transition heights from the IRI-2012 model lie within the uncertainty limit of WM sounding for night side, but for day side (L-shell>2.5) they are 200 km higher than WM uncertainty limits. (7) foF2 (F2 peak plasma densities) from ionosonde stations and the IRI-2012 model are ~1.5-3 MHz higher than those from WM sounding during daytime. These measurements are very important as the ion density profile along geomagnetic field lines is poorly known. They can lead to a better understanding of global cold plasma distribution inside the plasmasphere at low altitude and thereby bridge the gap between high topside ionosphere and plasmasphere measurements. These results will provide important guidance for the design of future space-borne sounders in terms of frequency and virtual range, in order to adequately cover ion density measurements at low altitudes and wide range of MLTs, solar and geophysical conditions

Hydrophobic hydration driven self-assembly of Curcumin in water: Similarities to nucleation and growth under large metastability, and an analysis of water dynamics at heterogeneous surfaces

As the beneficial effects of curcumin have often been reported to be limited to its small concentrations, we have undertaken a study to find the aggregation properties of curcumin in water by varying the number of monomers. Our molecular dynamics simulation results show that the equilibrated structure is always an aggregated state with remarkable structural rearrangements as we vary the number of curcumin monomers from 4 to 16 monomers. We find that curcumin monomers form clusters in a very definite pattern where they tend to aggregate both in parallel and anti-parallel orientation of the phenyl rings, often seen in the formation of beta-sheet in proteins. A considerable enhancement in the population of parallel alignments is observed with increasing the system size from 12 to 16 curcumin monomers. Due to the prevalence of such parallel alignment for large system size, a more closely packed cluster is formed with maximum number of hydrophobic contacts. We also follow the pathway of cluster growth, in particular the transition from the initial segregated to the final aggregated state. We find the existence of a metastable structural intermediate involving a number of intermediate-sized clusters dispersed in the solution. The course of aggregation bears similarity to nucleation and growth in highly metastable state. The final aggregated form remains stable with total exclusion of water from its sequestered hydrophobic core. We also investigate water structure near the cluster surface along with their orientation. We find that water molecules form a distorted tetrahedral geometry in the 1st solvation layer of the cluster, interacting strongly with hydrophilic groups at the surface of curcumin. The dynamics of such quasi-bound water molecules near the surface of curcumin cluster is considerably slower than the bulk signifying a restricted motion as often found in protein hydration layer.Comment: 31 pages, 9 figure

Diversity and distribution of wild mushrooms in different forest areas of Bankura district, WB, India

Mushrooms are macroscopic fruit bodies of fungi; one of the most diverse groups of living organisms distributed all over the world. In recent past, they have gained significant scientific attention for their profound nutraceutical potentiality. The objective of the present study was to explore the diversity and ecological distribution of mushrooms in different forest areas of Bankura district. The study area includes intermittent dense forest and flood plains from middle-east to eastern part of Bankura district. However, this area received very little attention from a conservation perspective, and there is no such documentation on mushrooms of this area. The survey was conducted from August 2019 to October 2020 including vivid field surveys in the forest depots. The study has revealed a total of 53 identified mushroom species belonging to 40 genera and 30 families. The study has also identified 25 edible, 18 inedible and 15 medicinally potential mushrooms. The genus Russula and the family Russulaceae dominates the myco-population. The finding shows that this region is rich in macrofungal diversity complicatedly linked to the functioning of the local ecosystem. The present study opens new possibilities regarding the exploration and utilization of wild mushrooms in India

Effect of clonidine as adjuvant in bupivacaine-induced supraclavicular brachial plexus block: A randomized controlled trial

Objective: Clonidine has been used as adjuvant to local anesthetics in order to extend the duration of analgesia in various regional and central neuraxial blocks. It is previously reported that clonidine added to bupivacaine increases analgesia duration in brachial plexus block. We evaluated the effect of this combination in supraclavicular brachial plexus block for upper limb orthopedic procedures. Materials and Methods: A randomized double-blind placebo controlled trial was done with 70 patients of American Society of Anesthesiologists Grade I or II status undergoing upper limb orthopedic procedures. Group A (n = 35) patients received 25 ml of 0.5% bupivacaine and 0.2 ml (30 mcg) clonidine, whereas group B (n = 35) received 25 ml of 0.5% bupivacaine and 0.2 ml normal saline through a supraclavicular approach for brachial plexus block. Vital parameters were recorded 10 min prior to block placement and every 3 min thereafter till the end of the procedure. Onset and duration of both sensory and motor blocks and sedation score were recorded. All patients were observed in postanesthesia care unit and received tramadol injection as soon as they complained of pain as rescue analgesic. Duration of analgesia was taken as the time from placement of block till injection of rescue analgesic. Results: Analgesia duration was 415.4 ± 38.18 min (mean ± standard deviation) in Group A (clonidine) compared to 194.2 ± 28.74 min in Group B (control). No clinically significant difference was observed in heart rate, blood pressure, and oxygen saturation. Sedation score was higher in the clonidine group. Conclusion: Addition of a small dose of clonidine to 0.5% bupivacaine significantly prolonged the duration of analgesia without producing any clinically important adverse reactions other than sedation

Sensitivity of polarization fluctuations to the nature of protein-water interactions: Study of biological water in four different protein-water systems

Since the time of Kirkwood, observed deviations in magnitude of the dielectric constant of aqueous protein solution from that of neat water (similar to 80) and slower decay of polarization have been subjects of enormous interest, controversy, and debate. Most of the common proteins have large permanent dipole moments (often more than 100 D) that can influence structure and dynamics of even distant water molecules, thereby affecting collective polarization fluctuation of the solution, which in turn can significantly alter solution's dielectric constant. Therefore, distance dependence of polarization fluctuation can provide important insight into the nature of biological water. We explore these aspects by studying aqueous solutions of four different proteins of different characteristics and varying sizes, chicken villin headpiece subdomain (HP-36), immunoglobulin binding domain protein G (GB1), hen-egg white lysozyme (LYS), and Myoglobin (MYO). We simulate fairly large systems consisting of single protein molecule and 20000-30000 water molecules (varied according to the protein size), providing a concentration in the range of similar to 2-3 mM. We find that the calculated dielectric constant of the system shows a noticeable increment in all the cases compared to that of neat water. Total dipole moment auto time correlation function of water < dM(W) (0)delta M-W (t) > is found to be sensitive to the nature of the protein. Surprisingly, dipole moment of the protein and total dipole moment of the water molecules are found to be only weakly coupled. Shellwise decomposition of water molecules around protein reveals higher density of first layer compared to the succeeding ones. We also calculate heuristic effective dielectric constant of successive layers and find that the layer adjacent to protein has much lower value (similar to 50). However, progressive layers exhibit successive increment of dielectric constant, finally reaching a value close to that of bulk 4-5 layers away. We also calculate shellwise orientational correlation function and tetrahedral order parameter to understand the local dynamics and structural re-arrangement of water. Theoretical analysis providing simple method for calculation of shellwise local dielectric constant and implication of these findings are elaborately discussed in the present work. (C) 2014 AIP Publishing LLC

Inadequacy of 12-week miltefosine treatment for Indian post-kala-azar dermal leishmaniasis

Post-kala-azar dermal leishmaniasis (PKDL) is a chronic dermatosis that generally occurs after apparent cure of visceral leishmaniasis caused by Leishmania donovani. In view of the prolonged treatment regimens necessary for PKDL, noncompliance is a major limitation; an optimal regimen is yet to be defined, but 12 weeks of therapy with miltefosine is generally recommended. We performed a single-arm open-label trial of miltefosine administered daily for 16 weeks in 27 patients in Kolkata with PKDL. After 4 weeks of treatment, nine patients were lost to follow-up because of unacceptable side effects, including severe abdominal pain, nausea, and vomiting. Of the 18 remaining patients, seven completed 12 weeks of therapy and 11 completed 16 weeks of therapy. Three of the seven who received 12 weeks of therapy and none of the 11 who received 16 weeks of therapy experienced disease relapse. Our results suggest that a 16-week course of miltefosine is required for reliable cure of PKDL. Further, the study highlighted the urgent need for a multicentric randomized controlled trial of 12 versus 16 weeks of treatment with miltefosine for PKDL so as to achieve the goal of elimination of leishmaniasis in south Asia

Structural insights into the interactions of repositioning and known drugs for Alzheimer’s disease with hen egg white lysozyme by MM-GBSA

Six drugs (dapsone, diltiazem, timolol, rosiglitazone, mesalazine, and milnacipran) that were predicted by network-based polypharmacology approaches as potential anti-Alzheimer’s drugs, have been subjected in this study for in silico and in vitro evaluation to check their potential against protein fibrillation, which is a causative factor for multiple diseases such as Alzheimer’s disease, Parkinson’s disease, Huntington disease, cardiac myopathy, type-II diabetes mellitus and many others. Molecular docking and thereafter molecular dynamics (MD) simulations revealed that diltiazem, rosiglitazone, and milnacipran interact with the binding residues such as Asp52, Glu35, Trp62, and Asp101, which lie within the fibrillating region of HEWL. The MM-GBSA analysis revealed −7.86, −5.05, and −10.29 kcal/mol as the binding energy of diltiazem, rosiglitazone, and milnacipran. The RMSD and RMSF calculations revealed significant stabilities of these ligands within the binding pocket of HEWL. While compared with two reported ligands inhibiting HEWL fibrillation, milnacipran depicted almost similar binding potential with one of the known ligands (Ligand binding affinity −10.66 kcal/mol) of HEWL. Furthermore, secondary structure analyses revealed notable inhibition of the secondary structural changes with our candidate ligand; especially regarding retention of the 3/10 α-helix both by DSSP simulation, Circular dichroism, and FESEM-based microscopic image analyses. Taking further into experimental validation, all three ligands inhibited fibrillation in HEWL in simulated conditions as revealed by blue shift in Congo red assay and later expressing percentage inhibition in ThioflavinT assay as well. However, dose-dependent kinetics revealed that the antifibrillatory effects of drugs are more pronounced at low protein concentrations. Communicated by Ramaswamy H. Sarma</p