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Ferromagnetic nematic suspensions with negative dielectric anisotropy: Competing effects of magnetic and electric fields
No full textThe successful development of ferromagnetic nematic liquid crystals (FNLCs) has opened up a new direction for research in liquid crystals, which has the potential for technological applications. Previous research has predominantly focused on FNLCs based on positive dielectric anisotropy liquid crystals. In this paper, we report the preparation and comprehensive characterization of an FNLC with low birefringence and negative dielectric anisotropy. The suspension was prepared by dispersing and stabilizing barium hexaferrite nanoplatelets in the nematic liquid crystal. The suspension exhibits superior magnetocapacitance and magnetoviscous effects compared with conventional isotropic ferrofluids. We show that electric and magnetic fields applied simultaneously perpendicular to the director have competing effects on the director’s alignment and the nanoplatelets’ magnetic moments. This ferromagnetic nematic suspension broadens the scope of fundamental studies and has the potential for applications in magnetoelectric and magneto-optic sensors
Fast and efficient Bayesian method to search for strongly lensed gravitational waves
No full textA small fraction of the gravitational-wave (GW) signals from binary black holes observable by ground-based detectors will be strongly lensed by intervening objects such as galaxies and clusters. Strong lensing will produce nearly identical copies of the GW signals separated in time. These lensed signals must be identified against a background of unlensed pairs GW events, some of which may appear similar by accident. This is usually done using fast, but approximate methods that, for example, check for the overlap between the posterior distributions of a subset of binary parameters, or using slow, but accurate joint Bayesian parameter estimation. In this work, we present a modified version of the posterior overlap method dubbed "PO2.0" that is mathematically equivalent to joint parameter estimation while still remaining fast. We achieve a significant gain in efficiency by incorporating informative priors about the binary and lensing populations, selection effects, and all the inferred parameters of the binary. For binary black hole signals lensed by galaxies, our improved method can detect 65% lensed events at a pairwise false alarm probability of ∼2 × 10-6. Consequently, we have a 13% probability of detecting a strongly lensed event above 2.25σ significance during 18 months of observation by the LIGO-Virgo detectors at their current sensitivity. We also show how we can compute the joint posteriors of the lens and source parameters from a pair of lensed events by reweighting the posteriors of individual events in a computationally inexpensive way
Conformational plasticity of mitochondrial VDAC2 controls the kinetics of its interaction with cytosolic proteins
No full textThe voltage-dependent anion channel (VDAC) is a key conduit of the mitochondrial outer membrane for water-soluble metabolites and ions. Among the three mammalian isoforms, VDAC2 is unique because of its embryonic lethality upon knockout. Using single-molecule electrophysiology, we investigate the biophysical properties that distinguish VDAC2 from VDAC1 and VDAC3. Unlike the latter, VDAC2 exhibits dynamic switching between multiple high-conductance, anion-selective substates. Using α-synuclein (αSyn)—a known VDAC1 cytosolic regulator—we found that higher-conductance substates correlate with increased on-rates of αSyn-VDAC2 interaction but shorter blockage times, maintaining a consistent equilibrium constant across all substates. This suggests that αSyn detects VDAC2’s dynamic structural variations before final binding. We explored the dependence of VDAC2’s unique amino-terminal extension and cysteines on substate behavior, finding that both structural elements modulate substate occurrence. The discovered conformational flexibility enables VDAC2 recognition by diverse binding partners, explaining its critical physiological role via dynamical adaptation to mitochondrial metabolic conditions
Studies of protein phase separation using leishmania kinetoplastid membrane protein-11
No full textDespite the significant understanding of phase separation in proteins with intrinsically disordered regions, a considerable percentage of proteins without such regions also undergo phase separation, presenting an intriguing area for ongoing research across all kingdoms of life. Using a combination of spectroscopic and microscopic techniques, we report here for the first time that a low temperature and low pH can trigger the liquid–liquid phase separation (LLPS) of a parasitic protein, kinetoplastid membrane protein-11 (KMP-11). Electrostatic and hydrophobic forces are found to be essential for the formation and stability of phase-separated protein assemblies. We show further that the increase in the ionic strength beyond a threshold decreases the interchain electrostatic interactions acting between the alternate charged blocks, altering the propensity for phase separation. More interestingly, the addition of cholesterol inhibits LLPS by engaging the cholesterol recognition amino acid consensus (CRAC)-like domains present in the protein. This was further confirmed using a CRAC-deleted mutant with perturbed cholesterol binding, which did not undergo LLPS
Cholesterol affects the pore formation and the membrane–membrane interaction induced by an antimicrobial peptide, nk-2, in phospholipid vesicles
No full textAntimicrobial peptides are part of the innate immune response and show their antimicrobial activity by forming pores, followed by disintegration of the membrane. Cholesterol in the membrane can affect the pore formation process, as cholesterol is known to alter the permeability and elastic properties of the membrane. The present research systematically explores the role of cholesterol in modulating the interaction of the antimicrobial peptide NK-2 with phospholipid membranes, as well as the processes of pore formation induced by NK-2 within the membrane. Large unilamellar vesicles (LUVs) and giant unilamellar vesicles (GUVs) made from DOPC-DOPG and Egg PC with varying cholesterol concentrations have been studied using a variety of experimental techniques. The present study revealed that both the magnitude of zeta potential and surface charge density diminished as cholesterol concentrations increased at an intermediate NK-2 concentration. The proliferation of the size distributions of LUVs containing cholesterol when exposed to NK-2 indicates the occurrence of vesicle aggregation. The phase contrast micrographs of GUVs as well as the calcein release experiments on LUVs show evidence of pores. Notably, the incorporation of cholesterol into the membrane was found to have a significant effect on both the permeability of the membrane and the kinetics of the pore formation process. This biophysical research contributes essential knowledge regarding the role of cholesterol in influencing the antimicrobial efficacy of the membrane
Stability assessment of pile foundations for an elevated viaduct: case study of the indore metro railway in India.
No full textThe present study focuses on the stability assessment of pile foundations for an elevated viaduct in the context of the Indore Metro Rail Project in India. The research addresses deviations observed during construction, particularly concerning some piles of Piers 2, 4, 5, and 7, which were found to be shorter than specified in design. The objective is to evaluate proposed remedial measures and revised designs to ensure both geotechnical and structural adequacy. Numerical analysis using PLAXIS 3D (version 21.00.01.7) is employed to assess the stability of pile groups under various load cases. Results are presented in terms of displacements, reactions, and moments for each pier and load case. From numerical analysis, it has been observed that maximum axial reactions in piles are within minimum capacities, maximum vertical settlements of piles meet permissible limits, and lateral deflections at pile tops are within acceptable bounds. The proposed designs for Piers P2, P4, P5, and P7 demonstrate sufficient structural integrity and geotechnical capacity to withstand anticipated loads from the viaduct structure while minimizing settlement within permissible limits. The study recommends the adoption of revised pile arrangements and adjustments in pile-cap designs to ensure enhanced stability and safety for the Indore Metro Rail Project
Invariant subspaces and the C<sub>00</sub>-property of Brownian shifts
No full textWe consider the restriction of Brownian shifts to their invariant subspaces and classify when they are unitarily equivalent. Additionally, we prove an asymptotic property stating that normalized Brownian shifts belong to the classical C00-class
Ionospheric response to the intense geomagnetic storm of 23–24 April 2023: Insights from ground-based airglow and GPS observations over low-latitude Indian regions
No full textIn the present study, night airglow emissions from the ionosphere and mesosphere were studied using a CCD-based all-sky imager (ASI) system located at a low-latitude Indian station in Kolhapur (16.8° N, 74.2° E, dip latitude 10.6° N). We have used the OI 630 nm, OI 557.7 nm and OH emission data. We analysed night airglow emissions during the intense geomagnetic storm of 23 April 2023, the strongest of the current solar cycle, with a minimum SYM-H of –233 nT. On the night of 22 April, strong equatorial plasma bubbles (EPBs) were observed in ASI images, drifting from west to east. On the storm day (23 April), EPBs appeared at 1400 UT and abruptly disappeared by 1730 UT in the OI 630.0 nm emission. The drift velocity of EPBs ranged from 140 to 40 m/s on 22 April and from 100 to 120 m/s on the storm day (23 April), showing notable differences compared to the previous storm event of 17 March 2015 over Kolhapur, where EPB move from west to east direction generally, but it moved in reverse direction on the strong magnetically disturbed night (17 March 2015). We noted observed EPB zonal velocity follow the trend of HWM-07 model estimated velocity. The significant variations in Total Electron Content (TEC) observed during the storm’s main and recovery phases likely reflect the influence of westward Disturbance Dynamo Electric Fields (DDEFs). These results may contribute to understanding the ionospheric response to severe geomagnetic storms under the influence of westward DDEFs during the dayside recovery phase
Coupling of downscaled GRACE data with SPHY derived hydrological components to generate snow water equivalent in the Himalayan catchment
No full textThis study demonstrated the applicability of Gravity Recovery and Climate Experiment (GRACE) satellite data through the coupling of multisource datasets in cryospheric and hydrological assessments over the Himalayan basin. For this purpose, a coupled modeling framework was developed using the fully distributed Spatial Process in Hydrology (SPHY) model, forced by real-time satellite and hydro-observation datasets. To reduce uncertainty in the outcomes, a two-step calibration approach was performed: (i) utilizing the observed discharge at two gauges, namely Maneri and Rishikesh, and (ii) comparing the MODIS-derived snow cover area (SCA) with the SPHY-derived SCA. The observed versus modeled discharge was found to be comparable, with the corresponding coefficient of determination (R2) recorded as 0.64 and 0.66 for Maneri and Rishikesh, respectively. The seasonal snow cover computed by SPHY was validated against MODIS snow cover maps, yielding a coefficient of determination of 0.73 (2015). By analyzing the snow mass loading and unloading using GRACE Total Water Storage Anomalies (TWSA) and MODIS snow cover data, sixteen snow seasons (between 2002 and 2020) were identified in the snow-glacier-dominated sub-basins of the Upper Ganga River. The snow water equivalent (SWE) was computed after subtracting other hydrological/water-balance components in these sub-basins. A spatial downscaling of GRACE TWSA was performed utilizing the GLDAS variables, showing significant improvement in the GRACE TWSA at a 0.25° × 0.25° scale. The correlation analysis showed a good match between GRACE and GLDAS variables (R2 up to ∼0.7). The downscaled GRACE-TWSA was compared with SPHY-TWSA and other cryospheric-hydrological components at different stations, with results found to be comparable. The results show that GRACE + SPHY SWE is comparable to GLDAS SWE in upstream regions, though some discrepancies exist downstream. For establishing the relationship between GRACE TWSA and hydrological components, cryosphere and hydrology variables such as snowmelt runoff, glacier melt runoff, baseflow, and rainfall-runoff were successfully separated at different stations (or sub-basins)
Error estimates for a bubble-enriched <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si3.svg" display="inline" id="d1e3029"><mml:msup><mml:mrow><mml:mi>C</mml:mi></mml:mrow><mml:mrow><mml:mn>0</mml:mn></mml:mrow></mml:msup></mml:math> interior penalty method to a reduced state constrained elliptic optimal control problem
No full textIn this article, we study a bubble-enriched Cy0 interior penalty method for the elliptic optimal control problem with pointwise control constraints. We have used the strategy of converting the control constrained optimization problem into a state constrained optimization problem by removing the control variable. The convergence behavior is obtained in H2 -like energy norm. We present numerical tests to validate our theoretical results