11563 research outputs found
Sort by
On semi-finite vector bundles with connection over Kahler manifolds
No full textLet X be a compact connected K¨ahler manifold. We consider the category C EC(X) of flat holomorphic connections (E, ∇E) over X satisfying the condition that the underlying holomorphic vector bundle E admits a filtration of holomorphic subbundles preserved by the connection ∇E such that the monodromy of the induced connection on each successive quotient has finite image. The category C EC(X), equipped with the neutral fiber functor that sends any object (E, ∇E) to the fiber Ex0 , where x0 ∈ X is a fixed point, defines a neutral Tannakian category over C. Let ϖEC(X, x0) denote the affine group scheme corresponding to this neutral Tannakian category C EC(X). Let π EN(X, x0) be an extension of the Nori fundamental group scheme over C [8]. We show that π EN(X, x0) is a closed subgroup scheme of ϖEC(X, x0). Finally, we discuss an example illustrating that if X is not K¨ahler, then the natural homomorphism π EN(X, x0) −→ ϖEC(X, x0) might fail to be an embedding
Gain, amplification, and lasing in a driven atom-cavity system
No full textCold atoms coupled to an optical cavity provide an ideal platform for creating lasers without conventional population inversion. Such lasers can generate very high spectral purity, and the output can be precisely controlled by varying the atom-drive or atom-cavity parameters. In this letter, we report experimental observation of gain, amplification, and self-lasing within a continuously operated85Rb magneto-optic trap (MOT), in the collective strong coupling regime of the atom-cavity system. The presence of MOT cooling lasers significantly alters the transmission properties of the cavity, and gain is observed in one of the vacuum Rabi peaks. The system makes a transition from an amplifying medium to a self-sustained laser as the MOT parameters are tuned. The underlying lasing mechanism is shown to be Mollow gain in the driven atomic ensemble, and is confirmed through the free-space absorption spectroscopy of the MOT. The free space gain required for the lasing action is significantly smaller in our system as compared to the cases where there is no collective strong coupling
Photoactivated Nano-Compatibilized Two-Phase Polymer Blends: An Approach for Determining Mechanical Behavior
No full textLight-activated polymers (LAPs) are shape-shifting materials capable of transforming their shapes in response to photoinduced chemical reactions, such as cis-trans isomerization and dimerization. Owing to the underlying photochemical reaction, these materials often exhibit behavior analogous to multicomponent/phase polymer blends. In this work, we present a free-energy-based theoretical framework to predict the mechanical behavior of nanoparticle-compatibilized elastic LAP blends that exhibit phase separation. In particular, we incorporate the impact of domain sizes and interfacial areas and establish a criterion for the materials’ susceptibility to mechanical failure under various loading conditions, namely uniaxial and biaxial stretching. Our framework can also be adapted to high-entropy polymers and thermoresponsive or light-activated systems, with potential applications in soft robotics, biomedical devices, micromechanics, 4D printing, and material origami. Additionally, by integrating our model with physics-informed neural networks, we facilitate efficient analysis of complex domain geometries and enable comprehensive parametric studies
Lithological controls on chemical weathering signatures in the semi-arid climatic regime: Study based on tropical small scale catchments
No full textLithological controls on chemical weathering can be better constrained by studying catchments having different lithologic settings in similar climatic conditions. This study compares the weathering fluxes in two small catchments having different lithology in semi-arid region (500–800 mm year-1 rainfall) in western India: The West Banas River (2100 km2 area, 372 m relief) draining granitic/gneissic rocks and the Berach River (610 km2 area; 542 m relief) flowing through shales. Sample collected in the year 2016 and 2017, were analysed for chemical composition to evaluate chemical weathering fluxes. Inverse model analysis and Soil and Water Assessment tool (SWAT) simulated runoff were combined to estimate the annual weathering fluxes. Total dissolved solids (TDS) in the West Banas ranged from 71 to 428 mgL−1(avg. 227 mgL−1), while the Berach River showed TDS of 190–712 mgL−1(avg. 370 mgL−1), with a few higher values due to anthropogenic sources. Silicate weathering rate (SilWR) is estimated as 7.7 ± 1.7 tons km−2y−1 for the granitic West Banas catchment whereas 5.7 ± 1.2 tons km−2y−1 for the shale lithology in the Berach River. The weathering susceptibility ratio of shale to granite is derived as 2:3. The weathering intensity is highly controlled by the susceptible minerals present in these rocks. The posteriori results of elemental ratios of the silicate endmember in shale lithology basin (Berach River) shows strong indication of incongruent weathering in the basin as a result of their constituting minerals has already gone through at least one cycle of chemical weathering during their formation. Saline-alkaline soils (SAS) contribute significantly to dissolved loads, especially in the Berach (38 ± 12 %), compared to the West Banas (26 ± 7 %). The cations derived from different lithologic sources have a dependency on the drainage basin area. However, other topographical factors showed minor control on chemical weathering
Accelerating distributed MPC via facet properties: faster computation with lower communication overhead
No full textExtreme Indian summer monsoon states stifled Bay of Bengal productivity across the last deglaciation
No full textIndian summer monsoon (ISM) hydrology fuels biogeochemical cycling across South Asia and the Indian Ocean, exerting a first-order control on food security in Earth’s most densely populated areas. Although the ISM is projected to intensify under continued greenhouse forcing, substantial uncertainty surrounds anticipating its impacts on future Indian Ocean stratification and primary production—processes key to the health of already-declining fisheries in the region. Here we present century-scale records of ISM runoff variability and marine biogeochemical impacts in the Bay of Bengal (BoB) since the Last Glacial Maximum (∼21 thousand years ago (ka)). These records reveal extreme monsoon states relative to modern strength, with weakest ISM intensity during Heinrich Stadial 1 (∼17.5–15.5 ka) and strongest during the early Holocene (∼10.5–9.5 ka). Counterintuitively, we find that BoB productivity collapsed during both extreme states of peak monsoon excess and deficits—both due to upper-ocean stratification. Our findings point to the possibility of future declines in BoB primary productivity under a strengthening and more variable ISM regime
Advancements in 3D-printed wearable sensors: a modern healthcare
No full textModern healthcare has been transformed by introducing 3D-printed wearable sensors, providing rapid, inexpensive, and customised diagnostic alternatives. An overview of 3D-printed wearable sensors, their development history, and the evolution of 3D printing technology are explored in this study, offering a thorough analysis of the developments associated with wearable sensors for modern healthcare and biomedical applications. Different 3D printing techniques, such as stereolithography, inkjet printing, fused deposition modelling, and other 3D printing methods, are summarised. The materials used for these techniques, such as flexible substrates, biocompatible composites, and conductive polymers, are thoroughly reviewed simultaneously, focusing on their relevance to healthcare. This review comprehensively examines the materials and methodologies used in developing 3D-printed wearable sensors for healthcare and biomedical applications, emphasising their significance, potential applications, and key findings from recent research. The study analyses the significant challenges posed by material limitations, printing resolution, and biocompatibility while critically assessing the primary advantages of 3D-printed wearable sensors, such as personalisation, rapid prototyping, and scalability. Design considerations are also thoroughly evaluated to maximise sensor performance and reliability, emphasising flexibility, durability, and user comfort. The overview further describes various healthcare applications of these sensors, from real-time diagnostic tools and continuous vital sign monitoring to rehabilitation devices. This review aims to provide valuable insights for researchers, engineers, and healthcare professionals by combining recent advancements and identifying current limitations. The review also explores future directions, focusing on sustainable materials for environmentally friendly sensor development and the integration of AI and IoT technologies for improved monitoring and diagnostics