130553 research outputs found
Sort by
Evaluating non-western disturbances winter precipitation over the western Himalayas
No full textWestern Himalayas (WH) receives precipitation through eastward propagating synoptic weather systems, Western Disturbances (WDs), embedded in large scale subtropical westerly jet (SWJ) during Northern Hemispheric boreal winter (December, January and February; DJF). In the recent decade, WDs have undergone certain changes in their characteristic’s viz., decreased associated precipitation, no significant changes in the WDs frequency and intensity, etc. However, Non-WDs days and associated precipitation gained its importance as it contributes ~ 20% of winter precipitation over WH. In this study, structure, dynamics and moisture availability associated with changing WDs and Non-WDs precipitating days are analyzed. Robust statistical methods and Theil-Sen slope on ERA5 data during 1987–2020 is considered to comprehend why active WDs’ (Non-WDs) precipitation frequency is declining (notably increasing). Interestingly, it is as well found that all the WDs do not precipitate and there are Non-WDs days when precipitation occur. It shows declining trend in WD precipitation and the increasing importance of Non-WDs. The findings show formation of ‘Ω shape’ flow - where high pressure is locked between two low pressure systems - over Indian subcontinent during Non-WDs days. Such dynamical wind col formation (‘Ω shape’) from lower (850Hpa) to upper (200 hPa) troposphere provides conducive situation for enhanced moisture incursion from Bay of Bengal (BoB) towards and over the WH during Non-WDs days leading to precipitation. This new finding needs to be looked from sustaining and replenishment of glaciers; agriculture; socioeconomic benefits during winters and needs to be addressed
Mixing twist-bend and ferroelectric nematic liquid crystals
No full textTwist-bend (Ntb) and ferroelectric (NF) nematic liquid crystals exhibit several novel effects and new physical properties. Here, we report experimental studies on the phase diagram and some physical properties of binary mixtures of CB9CB and RM734 mesogens. Both N-Ntb and N-NF phase transition temperatures and the corresponding enthalpies decrease significantly and, eventually, these transitions disappear at some intermediate compositions, stabilizing wide nematic phase (N). Temperature-dependent birefringence several degrees above the N-Ntb phase transition shows strong director tilt fluctuations. The critical range of the fluctuations increases with the nematic range and the critical exponent is consistent with the mean field. The spontaneous polarization of RM734 decreases drastically with the addition of CB9CB mesogen. The temperature dependence of the splay elastic constant of the mixtures' high-temperature nematic (N) phase strikingly differs from that of the pristine CB9CB and RM734 mesogens. The study shows that a small inclusion of either compound has a substantial effect on the phase diagram and physical properties
Electrophoretic propulsion of matchstick-shaped magnetodielectric particles in the presence of external magnetic fields in a nematic liquid crystal
No full textSynthesis of micro- and nanoparticles of pre-designed shape and surface properties is an integral part of soft and synthetic active matter. We report synthesis of matchstick-shaped (MS) magnetodielectric particles and demonstrate their potential as active agents with field-controllable trajectories in a nematic liquid crystal (NLC). The MS particles with homeotropic anchoring in NLCs align either parallel or perpendicular to the director depending on the dipolar or quadrupolar director distortions. When subjected to transverse electric and magnetic fields, the particles experience electric and magnetic torques trying to align them in the respective field directions. At equilibrium, the long axis is tilted at an angle with respect to the director. The change in orientation alters the surrounding elastic distortion, which results in unbalanced electroosmotic flows. These flows provide the necessary impetus for propelling the particles in various directions with different velocities depending on their orientations
Quasi-Optimality of an AFEM for General Second Order Elliptic PDE
No full textIn this article, convergence and quasi-optimal rate of convergence of an adaptive finite element method (in short, AFEM) is shown for a general second-order non-selfadjoint elliptic PDE with convection term bE[L∞(Ω)] d and using minimal regularity of the dual problem, i.e., the solution of the dual problem has only H1 -regularity, which extends the result [J. M. Cascon, C. Kreuzer, R. H. Nochetto and K. G. Siebert, Quasi-optimal convergence rate for an adaptive finite element method, SIAM J. Numer. Anal. 46 2008, 5, 2524–2550]. The theoretical results are illustrated by numerical experiments
Nanophotosensitizing through space charge transfer assemblies of pentacenequinone derivative for ‘metal‐free’ photoamidation reactions
No full textThe present study demonstrates the influence of small portion (20 %) of organic co-solvent (DMSO/THF/ACN/MeOH) in mixed aqueous media (80 % water) in controlling the size, quantum yield and life time of the through space charge transfer assemblies (TSCT) of pentacenequinone derivative (TPy-PCQ-TPy). Among various solvent systems [H2O : DMSO (8 : 2), H2O : THF (8 : 2), H2O : ACN (8 : 2) and H2O : MeOH (8 : 2)] examined, highly emissive (Φf=12 %) and nano-sized assemblies having long life time (3.11 ns) were formed in H2O : DMSO (8 : 2) solvent system. The solvent dependent differences in the size and excited state properties of TPy-PCQ-TPy assemblies are reflected in their photosensitizing behaviour in different solvent systems. Backed by excellent photosensitizing properties, TPy-PCQ-TPy assemblies smoothly catalyse the photoamidation reactions between unactivated/activated aldehydes and secondary amine under mild reaction conditions (visible light irradiation, aerial atmosphere, room temperature) in H2O : DMSO (8 : 2) solvent mixture. The as prepared assemblies of TPy-PCQ-TPy also exhibit high potential to catalyse the oxidation of benzyl alcohols to aromatic aldehydes, thus, generating a possibility to use aromatic alcohols as the starting material in photoamidation reactions. The real time application of TSCT assemblies has also been demonstrated in gram scale transformation of aromatic aldehydes to aromatic amides and photooxidation of benzyl alcohol to aromatic aldehyde
Interaction with IP6K1 supports pyrophosphorylation of substrate proteins by the inositol pyrophosphate 5-InsP<sub>7</sub>
No full textInositol pyrophosphates (PP-InsPs) are a sub-family of water soluble inositol phosphates that possess one or more diphosphate groups. PP-InsPs can transfer their β-phosphate group to a phosphorylated Ser residue to generate pyrophosphorylated Ser. This unique post-translational modification occurs on Ser residues that lie in acidic stretches within an intrinsically disordered protein sequence. Serine pyrophosphorylation is dependent on the presence of Mg2+ ions, but does not require an enzyme for catalysis. The mechanisms by which cells regulate PP-InsP-mediated pyrophosphorylation are still unknown. We performed mass spectrometry to identify interactors of IP6K1, an enzyme responsible for the synthesis of the PP-InsP 5-InsP7. Interestingly, IP6K1 interacted with several proteins that are known to undergo 5-InsP7-mediated pyrophosphorylation, including the nucleolar proteins NOLC1, TCOF and UBF1, and AP3B1, the β subunit of the AP3 adaptor protein complex. The IP6K1 interactome also included CK2, a protein kinase that phosphorylates Ser residues prior to pyrophosphorylation. We observe the formation of a protein complex between IP6K1, AP3B1, and the catalytic α-subunit of CK2, and show that disrupting IP6K1 binding to AP3B1 lowers its in vivo pyrophosphorylation. We propose that assembly of a substrate-CK2-IP6K complex would allow for coordinated pre-phosphorylation and pyrophosphorylation of the target serine residue, and provide a mechanism to regulate this enzyme-independent modification
Impact of rituximab maintenance on survival of patients with mantle cell lymphoma: A north Indian tertiary care center experience.
No full textBackground: Mantle cell lymphoma (MCL) is an aggressive variant of non-Hodgkin lymphoma. Indian data is scarce owing to its rarity in south-east Asia. Till now, studies have not shown overall survival benefit with rituximab maintenance (RM). Our study aims to assess if RM improves overall survival of MCL patients. Methods: We retrospectively analysed clinicopathological data of 90 transplant-ineligible MCL patients treated between January’2013-December’2023 at Institute Rotary Cancer Hospital - All India Institute of Medical Sciences, New Delhi, India. Rituximab-based induction chemotherapy was used in all patients as per institutional protocol. RM was used in twenty-eight (31.0%) patients due to financial constraints. Primary outcome was overall survival (OS). Secondary outcomes were event free survival (EFS) and factors affecting OS, EFS. OS was defined as time from treatment initiation to demise from any cause or last follow-up. EFS was defined as time from treatment initiation to disease progression or relapse or demise from any cause. Response was assessed by modified Cheson’s lymphoma response evaluation criteria. STATA 13.0 was used to assess survival by Kaplan-Meier analysis and log rank test. Factors affecting survival were assessed by multivariate analysis (Cox proportional hazards model) and expressed as adjusted hazard ratio (aHR). p value < 0.05 defined statistical significance. Results: Median age was sixty years; male-female ratio 3:1. Thirty-five (39.0%) had one or more co-morbidities, 79(88.0%) generalised lymphadenopathy, 72(80.0%) extra-nodal involvement, 49(54.0%) B symptoms, 84(93.0%) advanced stage (III/IV), 49(54.0%) high risk MCL international prognostic index (MIPI). Clinical and tumor characteristics, response rates after initial induction were similar in both maintenance and non-maintenance groups. Overall, 52(58.0%) patients were alive with median follow-up of 63.0 months (inter-quartile range 37.0-90.0 months). Median OS was 37.5 months in non-maintenance group and did not reach in maintenance group. Estimated 1.0-, 2.0, 3.0-year OS were 100.0%, 91.0%, 81.0% vs 75.0%, 63.0%, 55.0% respectively in maintenance vs non-maintenance group. RM was significantly associated with better OS [aHR (95% confidence interval): 0.31 (0.13-0.75), p=0.01]. Advanced stage, Eastern Co-operative Oncology Group performance status (ECOG PS) ≥2 at presentation were also significant factors for poor OS. Median EFS was significantly lower in non-maintenance group [14.0 vs 42.5 months; aHR (95% confidence interval): 0.34 (0.18-0.64), p=0.001]. Advanced stage, anemia, high risk MIPI at presentation were also significant factors for poor EFS. Conclusions: This was the first study from south-east Asia demonstrating impact of rituximab maintenance in MCL. Rituximab maintenance significantly improved OS and EFS of MCL patients
Habitat heterogeneity limits prey colour polymorphism maintained via negative frequency-dependent selection
No full textThe persistence of non-neutral trait polymorphism is enigmatic because stabilizing selection is expected to deplete variation. In cryptically
coloured prey, negative frequency-dependent selection due to search image formation by predators has been proposed to favour rare variants,
promoting polymorphism. However, in a heterogeneous environment, locally varying disruptive selection favours patch type-specific optima,
resulting in spatial segregation of colour variants. Here, we address whether negative frequency-dependent selection can overcome selection
posed by habitat heterogeneity to promote local polymorphism using an individual-based model. In addition, we compare how prey and predator
mobility may modify the outcome. Our model revealed that frequency-dependent predation could strongly promote local prey polymorphism,
but only when differences between morphs in patch-specific fitness were small. The effect of frequency-dependent predation depended on the
predator adjustment of search image and was hampered by the prey population structure. Gene flow due to prey movement counteracted local
selection, promoted local polymorphism to some extent, and relaxed the conditions for polymorphism due to frequency-dependent predation.
Importantly, abrupt spatial changes in morph frequencies decreased the probability that mobile frequency-dependent predators could maintain
local prey polymorphism. Overall, our study suggests that in a spatially heterogeneous environment, negative frequency-dependent selection may help maintain local polymorphism but only under a limited range of conditions
Unveiling Temperature-Induced Structural Phase Transition and Luminescence in Mn<sup>2+</sup>-Doped Cs<sub>2</sub>NaBiCl<sub>6</sub> Double Perovskite
No full textHalide double perovskites like Cs2NaBiCl6 are good host materials for luminescent dopants like Mn2+. The nature of photoluminescence (PL) depends on the local structure around the dopant ion, and doping may sometimes influence the global structure of the host. Here, we unveil the correlation between the temperature-induced (global) structural phase transition of Mn2+-doped Cs2NaBiCl6 with the local structure and PL of the Mn2+ dopant. X-ray diffraction analysis shows Mn2+-doped Cs2NaBiCl6 is in a cubic (Fm3m) phase between 300 and 110 K, below which the phase changes to tetragonal (I4/mmm), which persists at least until 15 K. The small (∼1%) doping amount does not alter the phase transition behavior of Cs2NaBiCl6. Importantly, the phase transition does not influence the Mn2+ d-electron PL. The PL peak energy, intensity, spectral width, and lifetime do not show any signature of the phase transition between 300–6 K. The hyperfine splitting in temperature-dependent electron paramagnetic spectra of Mn2+ ions also remain unchanged across the phase transition. These results suggest that the global structural phase transition of the host does not influence the local structure and emission property of the dopant Mn2+ ion. This structure–property insight might be explored for other transition-metal- and lanthanide-doped halide double perovskites as well. The stability of dopant emission regardless of the structural phase transition bodes well for their potential applications in phosphor-converted light emitting diodes
Projected increase in widespread riverine floods in India under a warming climate
No full textWidespread floods simultaneously affect several subbasins in a large river basin and pose severe challenges to disaster management and flood mitigation efforts. India is highly susceptible to widespread flooding as the country receives more than 70% of annual rainfall in the four-month period from June to September. However, the potential impacts of climate change on the drivers and frequency of widespread floods in India remain unexplored. We use observations, climate model simulations, and a hydrological model to examine the drivers and changes in widespread floods under a projected future climate. The observed increase in extreme precipitation does not translate to flooding in most river basins in India due to its fragmented nature. Translation of extreme precipitation to flood depends on the catchment area. We examined the changes in the widespread floods in Indian river basins using a hydrological model and climate projections. Robust increases in intense precipitation area and frequency are projected under the warming climate. Furthermore, hydrological model simulations indicate a profound increase in widespread floods in Indian river basins under a warming climate. The increase in widespread floods in a warming climate can pose challenges for flood mitigation and management in the future. Consideration of spatial extent of extreme precipitation and catchment area can enhance flood monitoring and prediction efforts. In addition, increases in extreme precipitation may not always lead to rise in flooding